Characteristics of ionic polymer-metal composite with chemically doped TiO2 particles

NASA Astrophysics Data System (ADS)

Jung, Youngsoo; Kim, Seong Jun; Kim, Kwang J.; Lee, Deuk Yong

2011-12-01

Many studies have investigated techniques to improve the bending performance of ionic polymer-metal composite (IPMC) actuators, including 'doping' of metal particles in the polymer membrane usually by means of physical processes. This study is mainly focused on the characterization of the physical, electrochemical and electromechanical properties of TiO2-doped ionic polymer membranes and IPMCs prepared by the sol-gel method, which results in a uniform distribution of the particles inside the polymer membrane. X-ray and UV-visible spectra indicate the presence of anatase-TiO2 in the modified membranes. TiO2-doped membranes (0.16 wt%) exhibit the highest level of water uptake. The glass transition temperature of these membranes, measured using differential scanning calorimetry (DSC), increases with the increase of the amount of TiO2 in the membrane. Dynamic mechanical analysis (DMA) demonstrated that the storage modulus of dried TiO2-doped ionic polymer membranes increases as the amount of TiO2 in the membrane increases, whereas the storage modulus of hydrated samples is closely related to the level of water uptake. Electrochemical impedance spectroscopy (EIS) shows that the conductivity of TiO2-doped membranes decreases with increasing TiO2 content in spite of an internal resistance drop in the samples. Above all, bending deflection of TiO2-doped IPMC decreased with higher TiO2 content in the membrane while the blocking force of each sample increased with the higher TiO2 content. Additionally, it was determined that the lifetime of IPMC is strongly dependent on the level of water uptake.

Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

PubMed

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-08-08

The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

Synthesis and electrochemical properties of Ti-doped DLC films by a hybrid PVD/PECVD process

NASA Astrophysics Data System (ADS)

Jo, Yeong Ju; Zhang, Teng Fei; Son, Myoung Jun; Kim, Kwang Ho

2018-03-01

Low electrical conductivity and poor adhesion to metallic substrates are the main drawbacks of diamond-like carbon (DLC) films when used in electrode applications. In this study, Ti-doped DLC films with various Ti contents were synthesized on metal Ti substrates by a hybrid PVD/PECVD process, where PECVD was used for deposition of DLC films and PVD was used for Ti doping. The effects of the Ti doping ratio on the microstructure, adhesion strength, and electrical and electrochemical properties of the DLC films were systematically investigated. An increase in the Ti content led to increased surface roughness and a higher sp2/sp3 ratio of the Ti-DLC films. Ti atoms existed as amorphous-phase Ti carbide when the Ti doping ratio was less than 2.8 at.%, while the nanocrystalline TiC phase was formed in DLC films when the Ti doping ratio was exceeded 4.0 at.%. The adhesion strength, electrical resistivity, electrochemical activity and reversibility of the DLC films were greatly improved by Ti doping. The influence of Ti doping ratio on the electrical and electrochemical properties of the DLC films were also investigated and the best performance was obtained at a Ti content of 2.8 at.%.

A study of TiB2/TiB gradient coating by laser cladding on titanium alloy

NASA Astrophysics Data System (ADS)

Lin, Yinghua; Lei, Yongping; Li, Xueqiao; Zhi, Xiaohui; Fu, Hanguang

2016-07-01

TiB2/TiB gradient coating has been fabricated by a laser cladding technique on the surface of a Ti-6Al-4V substrate using TiB2 powder as the cladding material. The microstructure and mechanical properties of the gradient coating were analyzed by SEM, EPMA, XRD, TEM and an instrument to measure hardness. With the increasing distance from the coating surface, the content of TiB2 particles gradually decreased, but the content of TiB short fibers gradually increased. Meanwhile, the micro-hardness and the elastic modulus of the TiB2/TiB coating showed a gradient decreasing trend, but the fracture toughness showed a gradient increasing trend. The fracture toughness of the TiB2/TiB coating between the center and the bottom was improved, primarily due to the debonding of TiB2 particles and the high fracture of TiB short fibers, and the fracture position of TiB short fiber can be moved to an adjacent position. However, the debonding of TiB2 particles was difficult to achieve at the surface of the TiB2/TiB coating.

Effect of Cu content on wear resistance and mechanical behavior of Ti-Cu binary alloys

NASA Astrophysics Data System (ADS)

Yu, Feifei; Wang, Hefeng; Yuan, Guozheng; Shu, Xuefeng

2017-04-01

Arc melting with nonconsumable tungsten electrode and water-cooled copper crucible was used to fabricate Ti-Cu binary alloys with different Cu contents in an argon atmosphere. The compositions and phase structures of the fabricated alloys were investigated by glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). Nanoindentation tests through continuous stiffness measurement were then performed at room temperature to analyze the mechanical behaviors of the alloys. Results indicated that the composition of each Ti-Cu binary alloy was Ti(100- x) Cu x ( x = 43, 60, 69, and 74 at.%). The XRD analysis results showed that the alloys were composed of different phases, indicating that different Cu contents led to the variations in alloy hardness. The wear tests results revealed that elemental Cu positively affects the wear resistance properties of the Ti-Cu alloys. Nanoindentation testing results showed that the moduli of the Ti-Cu alloys were minimally changed at increasing Cu content, whereas their hardness evidently increased according to the wear test results.

Studies on the performance of TiO{sub 2} thin films as protective layer to chlorophyll in Ocimum tenuiflorum L from UV radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malliga, P.; Selvi, B. Karunai; Pandiarajan, J.

Thin films of TiO{sub 2} were prepared on glass substrates using sol-gel dip coating technique. The films with 10 coatings were prepared and annealed at temperatures 350°C, 450°C and 550°C for 1 hour in muffle furnace. The annealed films were characterized by X – Ray diffraction (XRD), UV – Visible, AFM, Field Effect Scanning Electron Microscopy (FESEM) and EDAX studies. Chlorophyll has many health benefits due to its structural similarity to human blood and its good chelating ability. It has antimutagenic and anticarcinogenic properties. UV light impairs photosynthesis and reduces size, productivity, and quality in many of the crop plantmore » species. Increased exposure of UV light reduces chlorophyll contents a, b and total content in plants. Titanium Dioxide (TiO{sub 2}) is a wide band gap semiconductor and efficient light harvester. TiO{sub 2} has strong UltraViolet (UV) light absorbing capability. Here, we have studied the performance of TiO{sub 2} thin films as a protective layer to the chlorophyll contents present in medicinal plant, tulsi (Ocimum tenuiflorum L) from UV radiation. The study reveals that crystallite size increases, transmittance decreases and chlorophyll contents increases with increase in annealing temperature. This study showed that TiO{sub 2} thin films are good absorber of UV light and protect the chlorophyll contents a, b and total content in medicinal plants.« less

Microstructure, mechanical properties, bio-corrosion properties and antibacterial properties of Ti-Ag sintered alloys.

PubMed

Chen, Mian; Zhang, Erlin; Zhang, Lan

2016-05-01

In this research, Ag element was selected as an antibacterial agent to develop an antibacterial Ti-Ag alloy by a powder metallurgy. The microstructure, phase constitution, mechanical properties, corrosion resistance and antibacterial properties of the Ti-Ag sintered alloys have been systematically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), compressive test, electrochemical measurements and antibacterial test. The effects of the Ag powder size and the Ag content on the antibacterial property and mechanical property as well as the anticorrosion property have been investigated. The microstructure results have shown that Ti-Ag phase, residual pure Ag and Ti were the mainly phases in Ti-Ag(S75) sintered alloy while Ti2Ag was synthesized in Ti-Ag(S10) sintered alloy. The mechanical test indicated that Ti-Ag sintered alloy showed a much higher hardness and the compressive yield strength than cp-Ti but the mechanical properties were slightly reduced with the increase of Ag content. Electrochemical results showed that Ag powder size had a significant effect on the corrosion resistance of Ti-Ag sintered alloy. Ag content increased the corrosion resistance in a dose dependent way under a homogeneous microstructure. Antibacterial tests have demonstrated that antibacterial Ti-Ag alloy was successfully prepared. It was also shown that the Ag powder particle size and the Ag content influenced the antibacterial activity seriously. The reduction in the Ag powder size was benefit to the improvement in the antibacterial property and the Ag content has to be at least 3wt.% in order to obtain a strong and stable antibacterial activity against Staphylococcus aureus bacteria. The bacterial mechanism was thought to be related to the Ti2Ag and its distribution. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of Ti content on synthesis and characteristics of W-Ti ODS alloy

NASA Astrophysics Data System (ADS)

Chen, Chun-Liang; Zeng, Yong

2016-02-01

Tungsten-titanium alloys are considered as promising materials for the future fusion devices, in particular for the divertor and other first wall components. The microstructure and the mechanical properties of the material are dependent on the amount of Ti present in the alloy. In this study, W-Ti-Y2O3 alloys with varied Ti contents between 1 wt.% and 10 wt.% fabricated by mechanical alloying were investigated. The effect of Ti on the phase formation and mechanical properties of W-Ti-Y2O3 alloys has been examined. The results suggest that the alloys containing low Ti content exhibit homogeneous microstructure with a uniform distribution of fine titanium oxide particles and tungsten carbides, leading to a significant increase in hardness and elastic modulus of alloys. In addition, high-energy ball milling can facilitate a solid-state reaction between Y2O3 particles and the tungsten-titanium matrix and the subsequent sintering processing promotes the formation of stable nano Ti2Y2O7 oxide particles, which greatly increase the mechanical properties at elevated temperature and enhance irradiation resistance.

Effect of TiO2 addition on surface microstructure and bioactivity of fluorapatite coatings deposited using Nd:YAG laser.

PubMed

Chien, Chi-Sheng; Ko, Yu-Sheng; Kuo, Tsung-Yuan; Liao, Tze-Yuan; Lee, Tzer-Min; Hong, Ting-Fu

2014-04-01

To study the effect of titania (TiO2) addition on the surface microstructure and bioactivity of fluorapatite coatings, fluorapatite was mixed with TiO2 in 1:0.5 (FA + 0.5TiO2), 1:0.8 (FA + 0.8TiO2), and 1:1 (FA + TiO2) ratios (wt%) and clad on Ti-6Al-4V substrates using an Nd:YAG laser system. The experimental results show that the penetration depth of the weld decreases with increasing TiO2 content. Moreover, the subgrain structure of the coating layer changes from a fine cellular-like structure to a cellular-dendrite-like structure as the amount of TiO2 increases. Consequently, as the proportion of TiO2 decreases (increase in fluorapatite content), the Ca/P ratio of the coating layer also decreases. The immersion of specimens into simulated body fluid resulted in the formation of individual apatite. With a lower Ca/P ratio before immersion, the growth of the apatite was faster and then the coating layer provided a better bioactivity. X-ray diffraction analysis results show that prior to simulated body fluid immersion, the coating layer in all three specimens was composed mainly of fluorapatite, CaTiO3, and Al2O3 phases. Following simulated body fluid immersion, a peak corresponding to hydroxycarbonated apatite appeared after 2 days in the FA + 0.5TiO2 and FA + 0.8TiO2 specimens and after 7 days in the FA + TiO2 specimen. Overall, the results show that although the bioactivity of the coating layer tended to decrease with increasing TiO2 content, in accordance with the above-mentioned ratios, the bioactivity of all three specimens remained generally good.

Effect of Zirconium Addition on Microstructure and Mechanical Property of TiC/Ti6A14V Composites

NASA Astrophysics Data System (ADS)

Ma, Xuliang; Wang, Xiang; Li, Li; Gai, Pengtao; Zhu, Chengwu

TiC/Ti6A14V composites with different Zr additions were prepared successfully in a consumable vacuum arc furnace equipped with a water-cooled copper crucible and the effect of the Zr content on the microstructure and mechanical property of 15 vol.%TiC/Ti6A14V composites was investigated by XRD, SEM and hardness testing. The results show that when the level of Zr addition is less than 4 wt.%, the morphology of the primary TiC in the composites is dendrite, and the petal-shape, piece-shape or palpus-shape eutectic TiC separates out around the primary TiC. The average size of the primary TiC decreases and the amount of eutectic TiC increases gradually with increasing Zr content. The effects of Zr on morphology of the primary TiC weaken with further addition of Zr. And the hardness (HRC) of composites was obviously increased in the whole range of Zr addition. The refinement mechanism of Zr was attributed to the combined effects of increase in nucleation rate at the constitutionally supercooled zone ahead of the solidification front and reduction in growth rate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackerson, Michael R.; Tailby, Nicholas D.; Watson, E. Bruce

Titanium can be incorporated either tetrahedrally (IVTi) or octahedrally (VITi) in most silicate minerals. Ti K-edge X-ray absorption fine structure (XAFS) spectroscopy enables observation of Ti coordination in minerals and melts. In this study, XAFS is used to determine the coordination of Ti in synthetic and natural garnets. Garnets grown synthetically at eclogite- and granulite-facies conditions can contain several wt% TiO2, most of which is incorporated as VITi. This observation aligns with major element trends in these garnets. In natural garnets grown at lower temperatures and pressures, on the other hand, Ti is observed to occupy both the octahedral andmore » tetrahedral sites in garnet—in some cases Ti is almost entirely fourfold coordinated. Combined with previous research (see Ackerson et al. 2017, this issue) on substitution mechanisms for VITi, the results of this study demonstrate that Ti is incorporated on two crystallographic sites in garnet by at least three primary substitution mechanisms. In both natural and synthetic garnets, there is a discernible increase in VITi content in garnet with increasing temperature and pressure, suggesting a significant role for these two parameters in determining Ti solubility. However, a continuous increase in VITi with increasing grossular content also suggests that the Ca content of the garnet plays a critical role.« less

Effect of the content of B4C on microstructural evolution and wear behaviors of the laser-clad coatings fabricated on Ti6Al4V

NASA Astrophysics Data System (ADS)

Bai, L. L.; Li, J.; Chen, J. L.; Song, R.; Shao, J. Z.; Qu, C. C.

2016-01-01

TiNi/Ti2Ni-based composite coatings reinforced by TiC and TiB2 were produced on Ti6Al4V by laser cladding the mixture of a Ni-based alloy and different contents of B4C (0 wt%, 5 wt%, 15 wt%, and 25 wt%). The macromorphologies and microstructures of the coatings were examined through optical microscopy, X-ray diffractometry, scanning electron microscopy, and energy dispersive spectrometry. The microhardness, fracture toughness, and wear behaviors of the coatings were also investigated by using a microhardness tester and an ultra-functional wear testing machine. Results showed that the coatings were mainly composed of TiNi/Ti2Ni and TiC/TiB2 as the matrix and reinforcement particles, respectively. The phase constituents of the coatings were not influenced by addition of different contents of B4C. The microstructure of the reinforcements in the coatings presented the following evolution: hypereutectic consisting of blocky (TiC+TiB2)e eutectic and primary TiCp cellular dendrites (0 wt% B4C), mixture of hypereutectic and willow-shaped (TiB2+TiC)p pseudoeutectic (5 wt% B4C), and pseudoeutectic (15 and 25 wt% B4C). With increasing B4C content, the volume fraction and size of the pseudoeutectic structures as well as the average microhardness of the coatings (850, 889, 969, and 1002 HV0.2) were increased. By contrast, the average fracture toughness of the coatings was gradually decreased (4.47, 4.21, 4.06, and 3.85 Mpa m1/2) along with their wear volumes (0 wt%, 5 wt%, and 15 wt% B4C). The increase in B4C content to 25 wt% did not further reduce wear loss. The wear mechanism transformed from micro-cutting (0 wt% B4C) into a combination of micro-cutting and brittle debonding (5 wt% B4C) and finally led to brittle debonding (15 wt% and 25 wt% B4C). Coatings with suitable contents of B4C (less than 15 wt%) showed excellent comprehensive mechanical properties.

Interface activation and surface characteristics of Ti/TiN/HA coated sintered stainless steels

NASA Astrophysics Data System (ADS)

Choe, Han-Cheol; Ko, Yeong-Mu

2006-02-01

Interface activation and surface characteristics of Ti/TiN/HA film coated sintered stainless steels (SSS) have been investigated by electrochemical and biocompatibility tests. HA (hydroxyapatite), Ti, and Ti/TiN film coatings were applied using electron-beam deposition method (EB-PVD). Ti, Ti/TiN, and Ti/TiN/HA film coated surfaces and layers were investigated by SEM and XPS. The coated films showed micro-columnar structure, and Ti/TiN/HA films were denser than Ti or HA-only film. The corrosion resistance of the HA coating was similar to that of Ti/TiN/HA film coating when Cu content reached 4 wt.%, but the corrosion resistance of the HA coating decreased when Cu content increased from 4 wt.% in 0.9% NaCl solution. Therefore, HA-only coating could ensure corrosion resistance when Cu content does not exceed 4 wt.%. The results of biocompatibility tests of SSS on dogs showed that bone formation and biocompatibility were favorable when Cu content did not exceed 4 wt.%. The biocompatibility with bone was generally favorable in Ti/TiN/HA film coating and HA-only coating, while bone formation was somewhat faster for the HA film coated surface than for the Ti/TiN/HA film coating. Also, good cell growth and osseointegration without toxicity were observed.

Feasibility of Silver Doped TiO2/Glass Fiber Photocatalyst under Visible Irradiation as an Indoor Air Germicide

PubMed Central

Pham, Thanh-Dong; Lee, Byeong-Kyu

2014-01-01

This study investigated the feasibility of using Ag-TiO2 photocatalyst supported on glass fiber (Ag-TiO2/GF) prepared by a sol-gel method as an indoor air germicide. An experimental model was designed to investigate the bacterial disinfection efficiency of Staphylococcus (Staph), the most popular bacterium in hospitals in Korea, by the Ag-TiO2/GF photocatalyst. The silver content in Ag/TiO2 was altered from 1 to 10% to investigate the optimal ratio of Ag doped on TiO2/glass fiber (TiO2/GF) for photocatalytic disinfection of Staph. This study confirmed that Ag in Ag-TiO2/GF could work as an electron sink or donor to increase photocatalytic activity and promote the charge separation of electron-hole pairs generated from TiO2 after photon absorption. Ag also acts as an intermediate agent for the transfer of photo-generated electrons from the valence band of TiO2 to an acceptor (O2 gas) to promote photo-oxidation processes. The photocatalytic disinfection activity of Ag-TiO2/GF under visible light increased with the increase in silver content up to 7.5% and then slightly decreased with further increasing silver content. The highest disinfection efficiency and disinfection capacity of Staph using 7.5% Ag-TiO2/GF were 75.23% and 20 (CFU∙s−1∙cm−2) respectively. The medium level of humidity of 60% ± 5% showed better photocatalytic disinfection than the lower (40% ± 5%) or higher (80% ± 5%) levels. PMID:24658408

Synergistic Effect of Nitrogen and Refractory Material on TiN Formation and Equiaxed Grain Structure of Ferritic Stainless Steel

NASA Astrophysics Data System (ADS)

Lee, Mun Hyung; Park, Joo Hyun

2018-06-01

The effect of nitrogen content on the formation of an equiaxed solidification structure of Fe-16Cr steel was investigated. Moreover, two different kinds of refractory materials, i.e., alumina and magnesia, were employed to control the type of oxide inclusion. The characteristics of TiN(-oxide) inclusions were quantitatively analyzed in both molten steel and solidified samples. When the melting was carried out in the alumina refractory, the grain size continuously decreased with increasing nitrogen content. However, a minimum grain size was observed at a specific nitrogen content (approx. 150 ppm) when the steel was melted in the magnesia refractory. Most of the single TiN particles had a cuboidal shape and fine irregularly shaped particles were located along the grain boundary due to the microsegregation of Ti at the grain boundary during solidification. The type of TiN-oxide hybrid inclusion was strongly affected by the refractory material where Al2O3-TiN and MgAl2O4-TiN hybrid-type inclusions were obtained in the alumina and magnesia refractory experiments, respectively. The formation of oxide inclusions was well predicted by thermochemical computations and it was commonly found that oxide particles were initially formed, followed by the nucleation and growth of TiN. When the nitrogen content increased, the number density of TiN linearly increased in the alumina refractory experiments. However, the number of TiN exhibits a maximum at about [N] = 150 ppm, at which a minimum grain size was obtained in the magnesia refractory experiments. Therefore, the larger the number density of TiN, the smaller the primary grain size after solidification. The number density of TiN in the steel melted in the magnesia refractory was greater than that in the steel melted in the alumina refractory at given Ti and N contents, which was due to the lower planar lattice disregistry of MgAl2O4-TiN interface rather than that of Al2O3-TiN interface. When Δ T TiN (= difference between the TiN precipitation temperature and the liquidus of the steel) was 20 K to 40 K, the number density of effective TiN was maximized and thus, the grain size was minimized after solidification. Finally, although most of the TiN particles were smaller than 1 μm in the molten steel samples irrespective of the nitrogen content, TiN particles larger than 10 μm were observed in the solidified samples when the nitrogen content was greater than 150 ppm. The growth of TiN particles during melting and solidification was well predicted by the combinatorial simulation of the `Ostwald ripening model' based on the Lifshitz-Slyozov-Wagner theory in conjunction with the `Diffusion controlled model' using Ohnaka's microsegregation equation.

Synergistic Effect of Nitrogen and Refractory Material on TiN Formation and Equiaxed Grain Structure of Ferritic Stainless Steel

NASA Astrophysics Data System (ADS)

Lee, Mun Hyung; Park, Joo Hyun

2018-03-01

The effect of nitrogen content on the formation of an equiaxed solidification structure of Fe-16Cr steel was investigated. Moreover, two different kinds of refractory materials, i.e., alumina and magnesia, were employed to control the type of oxide inclusion. The characteristics of TiN(-oxide) inclusions were quantitatively analyzed in both molten steel and solidified samples. When the melting was carried out in the alumina refractory, the grain size continuously decreased with increasing nitrogen content. However, a minimum grain size was observed at a specific nitrogen content (approx. 150 ppm) when the steel was melted in the magnesia refractory. Most of the single TiN particles had a cuboidal shape and fine irregularly shaped particles were located along the grain boundary due to the microsegregation of Ti at the grain boundary during solidification. The type of TiN-oxide hybrid inclusion was strongly affected by the refractory material where Al2O3-TiN and MgAl2O4-TiN hybrid-type inclusions were obtained in the alumina and magnesia refractory experiments, respectively. The formation of oxide inclusions was well predicted by thermochemical computations and it was commonly found that oxide particles were initially formed, followed by the nucleation and growth of TiN. When the nitrogen content increased, the number density of TiN linearly increased in the alumina refractory experiments. However, the number of TiN exhibits a maximum at about [N] = 150 ppm, at which a minimum grain size was obtained in the magnesia refractory experiments. Therefore, the larger the number density of TiN, the smaller the primary grain size after solidification. The number density of TiN in the steel melted in the magnesia refractory was greater than that in the steel melted in the alumina refractory at given Ti and N contents, which was due to the lower planar lattice disregistry of MgAl2O4-TiN interface rather than that of Al2O3-TiN interface. When ΔT TiN (= difference between the TiN precipitation temperature and the liquidus of the steel) was 20 K to 40 K, the number density of effective TiN was maximized and thus, the grain size was minimized after solidification. Finally, although most of the TiN particles were smaller than 1 μm in the molten steel samples irrespective of the nitrogen content, TiN particles larger than 10 μm were observed in the solidified samples when the nitrogen content was greater than 150 ppm. The growth of TiN particles during melting and solidification was well predicted by the combinatorial simulation of the `Ostwald ripening model' based on the Lifshitz-Slyozov-Wagner theory in conjunction with the `Diffusion controlled model' using Ohnaka's microsegregation equation.

Thermoelectric properties of the ceramic oxide Sr1- x La x TiO3

NASA Astrophysics Data System (ADS)

Mahmud, Iqbal; Yoon, Man-Soon; Kim, Il-Ho; Choi, Moon-Kwan; Ur, Soon-Chul

2016-01-01

The effect of lanthanum on the electric and the thermoelectric properties of the ceramic oxide Sr1- x La x TiO3 (where x = 0.0, 0.04, 0.06, 0.08 and 0.12 mole) have been studied. La-doped SrTiO3 was prepared by using the conventional mixed-oxide reaction method. XRD patterns indicated that almost all the La atoms incorporated into the SrTiO3 crystal provided charge carriers. The lattice parameter increases with increasing La doping content. The relative densities of all the samples varied from 89.6% to 94.8%. The electrical conductivity increased with La doping up to 0.08 moles and then decreased as the content of La was increased above 0.08 moles. The thermal conductivity decreased with increasing La content. The largest absolute value of the Seebeck coefficient, 394 μVK-1 at 973 K, was observed at x = 0.04. The Sr0.92La0.08TiO3 sample showed its maximum electrical conductivity at 773 K and its largest ZT value of 0.20 at 973 K.

Structural, magnetic and Mossbauer studies of TI doped Gd2Fe17-xTix and Gd2Fe16Ga1-xTix (0≤x≤1)

NASA Astrophysics Data System (ADS)

Pokharel, G.; Syed Ali, K. S.; Mishra, S. R.

2015-05-01

Magnetic compounds of the type Gd2Fe17-xTix and Gd2Fe16Ga1-xTix (x=0.0-1.0) were prepared by arc melting and their structural and magnetic properties were studied by X-ray diffraction (XRD), magnetometery and Mossbauer spectroscopy. The Rietveld analysis of X-ray data shows that these α-Fe free solid-solutions crystallize with Th2Ni17-type structure as main phase along with GdFe2 and TiFe2 as additional phases at higher, x≥0.5 contents. The unit cell volume expands with Ga and Ti content. The Rietveld analysis indicate that both Ti and Ga atoms prefer 12j and 12k sites in both compounds. The effect of Ti and co-substituted Ga-Ti on the bond length are quite different. The saturation magnetization Ms, at 300 K for Gd2Fe17-xTix and Gd2Fe16Ga1-xTix was found to decrease linearly with increasing Ti content. The Ms in both compounds at x=1 reduced by 9% as compared to their parent compounds at x=0. The Curie temperature, Tc, for Gd2Fe17-xTix increased from 513 K (x=0) to 544 K (x=1) while Tc for Gd2Fe16Ga1-xTix reduced from 560 (x=0) to 544 K (x=1) with increase in Ti content. Thus the observed variation in Tc follows Gd2Fe17

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu Tangkui, E-mail: zhutangkui@sohu.com; Li, Miaoquan, E-mail: honeymli@nwpu.edu.cn

Effect of hydrogen content on the lattice parameter of Ti-6Al-4V alloy has been investigated by X-ray diffraction. The experimental results show that the solution of hydrogen in the Ti-6Al-4V alloy affects significantly on the lattice parameters of {alpha}, {beta} and {delta} phases, especially the {beta} phase. Furthermore, the critical hydrogen content of {delta} hydride formation for Ti-6Al-4V alloy is 0.385 wt.%. When the hydrogen content is lower than the critical hydrogen content, the {delta} hydride cannot precipitate and the lattice parameter ({alpha}) of {beta} phase linearly increases with the increasing of hydrogen content. When the hydrogen content is higher thanmore » the critical hydrogen content, the {delta} hydride precipitates and the lattice parameter ({alpha}) of {beta} phase varies inconspicuously with hydrogen content. In addition, the effects of lattice variations and {delta} hydride formation on microstructure are discussed. The {alpha}/{beta} interfaces of lamellar transformed {beta} phase become fuzzy with the increasing of hydrogen content because of the lattice expansion of {beta} phase. Compared with that of the Ti-6Al-4V alloy at low hydrogen content ({<=} 0.385 wt.%), the contrasts of primary {alpha} phase and transformed {beta} phase of Ti-6Al-4V alloy at high hydrogen content ({>=} 0.385 wt.%) were completely reversed due to the formation of {delta} hydride. - Research Highlights: {yields} A novel method for determining {delta} hydride in Ti-6Al-4V alloy is presented. {yields} The critical hydrogen content of {delta} hydride formation is 0.385 wt.%. {yields} The lattice parameter of {beta} phase can be expressed as follows: a=0.323(1+9.9x10{sup -2}C{sub H}) . {yields} Precipitation of {delta} hydride has a significant influence on the microstructure. {yields} The {alpha}/{beta} interfaces of transformed {beta} phase became fuzzy in the hydrogenated alloy.« less

[Photophysical properties of poly (2-methoxy-5-octyloxy)-p-phenylene vinylene/TiO2 nano-composites].

PubMed

Sun, Jian-ping; Weng, Jia-bao; Cheng, Yun-tao; Lin, Ting; Huang, Xiao-zhu

2008-12-01

The photoelectric composites of poly (2-methoxy-5-octyloxy)-p-phenylene vinylene/nanometer TiO2 (PMOCOPV/ TiO2) with different nanometer TiOz amount were synthesized through dehydrochlorination in-situ polymerization. The results of Fourier transform infrared spectroscopy and Raman spectroscopy indicated that the surface of nanometer TiO2 was coated with PMOCOPV. UV-Vis spectrum showed that the absorption of PMOCOPV/TiO2 nano-composites was strengthened in the range of violet and visible light with the contents of TiO2 increasing. The composite dimensions were observed by highly resolution transmission electron microscope, PMOCOPV/TiO2 nano-composites dispersed uniformly and possessed core-shell structure, the diameter of PMOCOPV/TiO2 was measured to be about 30 nm, and the thickness of the PMOCOPV coating was about 8-10 nm. Photoluminescence spectroscopy indicated that the maximum emission wavelength of the PMOCOPV/TiO2 was red-shifted with increasing TiO2 concentration. The fluorescence lifetime of PMOCOPV/TiO2 was about 1 ns. The intensity and lifetime of fluorescence was increased remarkably with the contents of TiO2 increasing. The mechanism of the strengthened fluorescence quantum efficiency and fluorescence intensity of PMOCOPV/TiO2 was investigated through the charge transfer, exciton dissociation and potential energy in PMOCOPV/TiO2 nano-composites.

Mechanical properties and biocompatibility of the sputtered Ti doped hydroxyapatite.

PubMed

Vladescu, A; Padmanabhan, S C; Ak Azem, F; Braic, M; Titorencu, I; Birlik, I; Morris, M A; Braic, V

2016-10-01

The hydroxyapatite enriched with Ti were prepared as possible candidates for biomedical applications especially for implantable devices that are in direct contact to the bone. The hydroxyapatites with different Ti content were prepared by RF magnetron sputtering on Ti-6Al-4V alloy using pure hydroxyapatite and TiO2 targets. The content of Ti was modified by changing the RF power fed on TiO2 target. The XPS and FTIR analyses revealed the presence of hydroxyapatite structure. The hardness and elastic modulus of the hydroxyapatite were increased by Ti addition. After 5 days of culture, the cell viability of the Ti-6Al-4V was enhanced by depositing with undoped or doped hydroxyapatite. The Ti additions led to an increase in cell viability of hydroxyapatite, after 5 days of culture. The electron microscopy showed the presence of more cells on the surface of Ti-enriched hydroxyapatite than those observed on the surface of the uncoated alloys or undoped hydroxyapatite. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermodynamic Simulation of Viscosity of TiO2-Ti2O3-CaO Ternary Slag

NASA Astrophysics Data System (ADS)

Zhang, P.; Ma, W. H.; Zhang, S. J.; Lei, Y.; Wen, J. H.

2017-12-01

The viscosity of high titanium slag at high temperature is one of the key factors of slag-iron separation. Based on the Einstein-Roscoe equation, thermodynamic simulation of viscosity of TiO2-Ti2O3-CaO ternary slag is studied by using FactSage® software, and the effects of temperature, CaO content and solid-phase particles on the viscosity of slag were studied. The results show that the increase of CaO content has the effect of reducing melting temperature and viscosity of TiO2-Ti2O3-CaO ternary slag. After the TiO2-Ti2O3-CaO ternary slag is completely melted, the increase of temperature has little effect on viscosity of slag, and the viscosity is about 110~125mPa·s. When the temperature is lower than melting temperature, TiO2-Ti2O3-CaO ternary slag will precipitate solid-phase particles, and the precipitation process is carried out in stages, and with the decrease of temperature, the precipitation will increase and the viscosity will sharply increase. TiO2-Ti2O3-CaO ternary titanium slag has obvious characteristics of short slag.

Investigation on Viscosity and Nonisothermal Crystallization Behavior of P-Bearing Steelmaking Slags with Varying TiO2 Content

NASA Astrophysics Data System (ADS)

Wang, Zhanjun; Sun, Yongqi; Sridrar, Seetharaman; Zhang, Mei; Zhang, Zuotai

2017-02-01

The viscous flow and crystallization behavior of CaO-SiO2-MgO-Al2O3-FetO-P2O5-TiO2 steelmaking slags have been investigated over a wide range of temperatures under Ar (High purity, >99.999 pct) atmosphere, and the relationship between viscosity and structure was determined. The results indicated that the viscosity of the slags slightly decreased with increasing TiO2 content. The constructed nonisothermal continuous cooling transformation (CCT) diagrams revealed that the addition of TiO2 lowered the crystallization temperature. This can mainly be ascribed to that addition of TiO2 promotes the formation of [TiO6]-octahedra units and, consequently, the formation of MgFe2O4-Mg2TiO4 solid solution. Moreover, the decreasing viscosity has a significant effect on enhancing the diffusion of ion units, such as Ca2+ and [TiO4]-tetrahedra, from bulk melts to the crystal-melt interface. The crystallization of CaTiO3 and CaSiTiO5 was consequently accelerated, which can improve the phosphorus content in P-enriched phase ( n2CaO·SiO2-3CaO·P2O5). Finally, the nonisothermal crystallization kinetics was characterized and the activation energy for the primary crystal growth was derived such that the activation energy increases from -265.93 to -185.41 KJ·mol-1 with the addition of TiO2 content, suggesting that TiO2 lowered the tendency for the slags to crystallize.

Influence of Mn contents in 0Cr18Ni10Ti thin wall stainless steel tube on TIG girth weld quality

NASA Astrophysics Data System (ADS)

Liu, Bo

2017-03-01

Three kinds of cold worked 0Cr18Ni10Ti thin wall stainless steel tubes with the manganese contents of 1.27%, 1.35% and 1.44% and the cold worked 0Cr18Ni10Ti stainless steel end plug with manganese content of 1.35% were used for TIG girth welding in the present investigation. The effect of different manganese contents in stainless steel tube on weld quality was studied. The results showed that under the same welding conditions, the metallographic performance of the girth weld for the thin wall stainless steel tube with the manganese element content 1.44% welded with end plug was the best. Under the appropriate welding conditions, the quality of the girth weld increased with the increase of the manganese content till 1.44%. It was found that in the case of the Mn content of 1.44%, and under the proper welding condition the welding defects, such as welding cracks were effectively avoided, and the qualified weld penetration can be obtained.. It is concluded that the appropriate increase of the manganese content can significantly improve the TIG girth weld quality of the cold worked 0Cr18Ni10Ti stainless steel tube.

Effects of TiO2 nanoparticles on wheat (Triticum aestivum L.) seedlings cultivated under super-elevated and normal CO2 conditions.

PubMed

Jiang, Fuping; Shen, Yunze; Ma, Chuanxin; Zhang, Xiaowen; Cao, Weidong; Rui, Yukui

2017-01-01

Concerns over the potential risks of nanomaterials to ecosystem have been raised, as it is highly possible that nanomaterials could be released to the environment and result in adverse effects on living organisms. Carbon dioxide (CO2) is one of the main greenhouse gases. The level of CO2 keeps increasing and subsequently causes a series of environmental problems, especially for agricultural crops. In the present study, we investigated the effects of TiO2 NPs on wheat seedlings cultivated under super-elevated CO2 conditions (5000 mg/L CO2) and under normal CO2 conditions (400 mg/L CO2). Compared to the normal CO2 condition, wheat grown under the elevated CO2 condition showed increases of root biomass and large numbers of lateral roots. Under both CO2 cultivation conditions, the abscisic acid (ABA) content in wheat seedlings increased with increasing concentrations of TiO2 NPs. The indolepropioponic acid (IPA) and jasmonic acid (JA) content notably decreased in plants grown under super-elevated CO2 conditions, while the JA content increased with increasing concentrations of TiO2 NPs. Ti accumulation showed a dose-response manner in both wheat shoots and roots as TiO2 NPs concentrations increased. Additionally, the presence of elevated CO2 significantly promoted Ti accumulation and translocation in wheat treated with certain concentrations of TiO2 NPs. This study will be of benefit to the understanding of the joint effects and physiological mechanism of high-CO2 and nanoparticle to terrestrial plants.

Aligned macroporous TiO2/chitosan/reduced graphene oxide (rGO) composites for photocatalytic applications

NASA Astrophysics Data System (ADS)

Chen, Chao; Zhang, Yan; Zeng, Jing; Zhang, Fuqiang; Zhou, Kechao; Bowen, Chris R.; Zhang, Dou

2017-12-01

In this article ice templating is used to fabricate novel TiO2/chitosan/reduced graphene oxide (rGO) composites with a highly aligned macroporous structure for photocatalytic applications. The structure of the composites was readily tailored using the composite composition, for example the lamellar pore width decreased from 50-45 to 5-10 μm, while the lamellar thickness increased from 2-3 to 20-25 μm, with an increase of the TiO2 content from 45 to 77 vol%. Lamellar pore channels between the layers exhibited a more uniform distribution when the rGO content was 1.0 wt%. The increase in viscosity of the composites with high TiO2 contents led to the formation of smaller ice crystals and smaller lamellar pore sizes to enable the production of composite structures with improved mechanical strength. The TiO2/chitosan/rGO composites exhibited excellent photocatalytic degradation of methyl orange and the photocatalytic efficiency was optimized by control of the active material content and microstructure. The hybrid composites with 1.0 wt% rGO showed a degradation percentage of 97%, which makes these novel TiO2/chitosan/rGO freeze cast structures attractive materials as high performance and high strength substrates for photocatalytic degradation applications.

Structure, mechanical properties, and grindability of dental Ti-Zr alloys.

PubMed

Ho, Wen-Fu; Chen, Wei-Kai; Wu, Shih-Ching; Hsu, Hsueh-Chuan

2008-10-01

Structure, mechanical properties and grindability of a series of binary Ti-Zr alloys with zirconium contents ranging from 10 to 40 wt% have been investigated. Commercially pure titanium (c.p. Ti) was used as a control. Experimental results indicated that the diffraction peaks of all the Ti-Zr alloys matched those for alpha Ti. No beta-phase peaks were found. The hardness of the Ti-Zr alloys increased as the Zr contents increased, and ranged from 266 HV (Ti-10Zr) to 350 HV (Ti-40Zr). As the concentration of zirconium in the alloys increased, the strength, elastic recovery angles and hardness increased. Moreover, the elastically recoverable angle of Ti-40Zr was higher than of c.p. Ti by as much as 550%. The grindability of each metal was found to be largely dependent on the grinding conditions. The Ti-40Zr alloy had a higher grinding rate and grinding ratio than c.p. Ti at low speed. The grinding rate of the Ti-40Zr alloy at 500 m/min was about 1.8 times larger than that of c.p. Ti, and the grinding ratio was about 1.6 times larger than that of c.p. Ti. Our research suggested that the Ti-40Zr alloy has better mechanical properties, excellent elastic recovery capability and improved grindability at low grinding speed. The Ti-40Zr alloy has a great potential for use as a dental machining alloy.

Huge photoresistance in transparent and conductive indium titanium oxide films prepared by electron beam-physical vapor deposition.

PubMed

Martínez-Morillas, Rocío; Ramírez, Rafael; Sánchez-Marcos, Jorge; Fonda, Emiliano; de Andrés, Alicia; Prieto, Carlos

2014-02-12

Transparent and conductive indium titanium oxide (ITiO) films have been obtained by electron beam physical vapour deposition with Ti content from 5 at % up to 28 at %. X-ray absorption spectroscopy techniques have been used to identify the local environment of Ti ions. Even at the lowest concentrations Ti is not incorporated into the In2O3 structure but forms clusters of a Ti-In mixed oxide that present a distorted rutile TiO2 short-range order. The optical transmittance of the annealed samples reaches 95 % and no significant variation of the gap energy (around 3.7 eV) is observed with Ti content. The electronic conductivity under light irradiation is studied evidencing a huge photo-resistance in the samples with Ti content above 22 at % reaching more than two orders of magnitude for the 26 at % Ti under illumination with few μW/cm(2) at 365 nm. Hall and conductivity results are analyzed using a model that takes into account both electron and hole carriers as well as the conductivity enhancement by carrier photogeneration. The electron carrier density decreases with Ti content while its mobility increases up to values of 1000 cm(2)/(V s). Oxygen annealed ITiO films obtained by this technique with Ti content below 10 at % have properties adequate as transparent semiconductors and those with Ti content higher than 22 at % have exceptional photoresistive properties relevant for numerous applications.

Experimental Study on Impact-Induced Reaction Characteristics of PTFE/Ti Composites Enhanced by W Particles.

PubMed

Li, Yan; Wang, Zaicheng; Jiang, Chunlan; Niu, Haohao

2017-02-13

Metal/fluoropolymer composites are a category of energetic structural materials that release energy through exothermic chemical reactions initiated under highly dynamic loadings. In this paper, the chemical reaction mechanism of PTFE (polytetrafluoroethylene)/Ti/W composites is investigated through thermal analysis and composition analysis. These composites undergo exothermic reactions at 510 °C to 600 °C, mainly producing TiF x . The tungsten significantly reduces the reaction heat due to its inertness. In addition, the dynamic compression properties and impact-induced reaction behaviors of PTFE/Ti/W composites with different W content prepared by pressing and sintering are studied using Split Hopkinson Pressure Bar and high speed photography. The results show that both the mechanical strength and the reaction degree are significantly improved with the increasing strain rate. Moreover, as W content increases, the mechanical strength is enhanced, but the elasticity/plasticity is decreased. The PTFE/Ti/W composites tend to become more inert with the increasing W content, which is reflected by the reduced reaction degree and the increased reaction threshold for the impact ignition.

Experimental Study on Impact-Induced Reaction Characteristics of PTFE/Ti Composites Enhanced by W Particles

PubMed Central

Li, Yan; Wang, Zaicheng; Jiang, Chunlan; Niu, Haohao

2017-01-01

Metal/fluoropolymer composites are a category of energetic structural materials that release energy through exothermic chemical reactions initiated under highly dynamic loadings. In this paper, the chemical reaction mechanism of PTFE (polytetrafluoroethylene)/Ti/W composites is investigated through thermal analysis and composition analysis. These composites undergo exothermic reactions at 510 °C to 600 °C, mainly producing TiFx. The tungsten significantly reduces the reaction heat due to its inertness. In addition, the dynamic compression properties and impact-induced reaction behaviors of PTFE/Ti/W composites with different W content prepared by pressing and sintering are studied using Split Hopkinson Pressure Bar and high speed photography. The results show that both the mechanical strength and the reaction degree are significantly improved with the increasing strain rate. Moreover, as W content increases, the mechanical strength is enhanced, but the elasticity/plasticity is decreased. The PTFE/Ti/W composites tend to become more inert with the increasing W content, which is reflected by the reduced reaction degree and the increased reaction threshold for the impact ignition. PMID:28772534

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiegs, T.N.

TiC-Ni{sub 3}Al cermets are under development for application in diesel engines because of desirable physical properties and wear resistance. Powder compacts with binder contents from 30-50 vol. % were fabricated by pressureless sintering under vacuum followed by low gas pressure isostatic pressing. Increasing the Ni{sub 3}Al content improved densification when using prealloyed powders as expected. However, when the Ni{sub 3}Al was formed by in-situ reaction synthesis of Ni and NiAl, densification decreased with higher binder contents. The final microstructure consisted of a ''core-rim'' structure with TiC cores surrounded by (Ti,W)C rims. In some cases, Ni and Al were also observedmore » in the peripheral region of the rim structure. Grain sizes of the TiC increased with binder content and temperature. Preferred orientation of the Ni{sub 3}Al binder phase was observed due to very large grain sizes on the order of millimeters.« less

Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

PubMed

Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

2013-12-01

The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility. © 2013 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, Wentao; Sun, Xuguang; Yuan, Bifei

The microstructures, phase transformations and shape memory properties of Ti-30Zr-xNb (x = 5, 7, 9, 13 at.%) alloys were investigated. The X-ray diffraction and transmission electron microscopy observations showed that the Ti-30Zr-5Nb, Ti-30Zr-7/9Nb and Ti-30Zr-13Nb alloys were composed of the hcp α′-martensite, orthorhombic α″-martensite and β phases, respectively. The results indicated the enhanced β-stabilizing effect of Nb in Ti-30Zr-xNb alloys than that in Ti-Nb alloys due to the high content of Zr. The differential scanning calorimetry test indicated that the Ti-30Zr-5Nb alloy displayed a reversible transformation with a high martensitic transformation start temperature of 776 K and a reverse martensiticmore » transformation start temperature (A{sub s}) of 790 K. For the Ti-30Zr-7Nb and Ti-30Zr-9Nb alloys, the martensitic transformation temperatures decreased with the increasing Nb content. Moreover, an ω phase transformation occurred in the both alloys upon heating at a temperature lower than the corresponding A{sub s}, which is prompted by more addition of Nb. Although the critical stress in tension of the three martensitic alloys decreased with increasing Nb content, the Ti-30Zr-9Nb alloy showed a critical stress of as high as 300 MPa. Among all the alloys, the Ti-30Zr-9Nb alloy exhibited the maximum shape memory effect of 1.61%, due to the lowest critical stress for the martensite reorientation. - Highlights: •Ti-30Zr-5Nb alloy is composed of hcp α′-martensite with the M{sub s} of 776 K. •Ti-30Zr-7Nb and Ti-30Zr-9Nb alloys are predominated by orthorhombic α″-martensite. •Ti-30Zr-13Nb alloy consists of a single β phase due to the β-stabilizing effect of Nb. •The martensitic transformation temperatures decrease with increasing Nb content. •Ti-30Zr-9Nb alloy shows the maximum shape memory effect of 1.61%.« less

Creation of Y2Ti2O7 nanoprecipitates to strengthen the Fe-14Cr-3Al-2W steels by adding Ti hydride and Y2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Wang, Linbo; Bai, Zhonglian; Shen, Hailong; Wang, Chenxi; Liu, Tong

2017-05-01

In order to prohibit the formation of large Y-Al-O precipitates, Ti hydride nanoparticles (NPs) were prepared and used to replace Ti as raw particles to fabricate the oxide dispersion strengthened (ODS) Fe-14Cr-3Al-2W-0.35Y2O3 steels by mechanical alloying (MA) and hot isostatic pressing (HIP). As the content of Ti hydride increases from 0.1 to 0.5 and 1.0 wt%, the oxide nanoprecipitates in the ODS steels changes from Y3Al5O12 phase to Y2Ti2O7 phase (semicoherent with the matrix), and the particle size is successfully reduced. The tensile strength of the ODS steel increases remarkably with increasing Ti hydride content. The sample with 1.0 wt% Ti hydride exhibits a high strength of 1049 MPa at 25 °C and 278 MPa at 700 °C. The creation of Y2Ti2O7 nanoprecipitates by adding Ti hydride NPs opens a new way to control the structure and size of the oxide precipitates in the ODS steels.

Development of casting investment preventing blackening of noble metal alloys part 3. Effect of reducing agent addition on the strength and expansion of the investments.

PubMed

Meng, Yukun; Nakai, Akira; Ogura, Hideo

2004-06-01

Different reducing agents (B, Al, Si and Ti) were individually added to two gypsum-bonded investments to prepare investments preventing surface blackening of some noble cast alloys. The effect of different additive contents on green-body and burnout compressive strength, setting and thermal expansion of the investments were evaluated. The strength and expansion of the investments were changed by the additives. The compressive strength of Al-, Si- and Ti-added investments decreased with the increase of additive contents. The burnout strength of B-added investments significantly increased while green-body strength remained unchanged. The setting expansion of the B-added investments increased while those of the Al-, Si- and Ti-added investments decreased with the increase of additive contents. The thermal expansion of the Si- and Ti-added investments decreased, and that of the Al- and B-added investments remained unchanged. Further study is necessary to evaluate the effects of these additives on the accuracy of dental castings.

Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

NASA Astrophysics Data System (ADS)

Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

2016-05-01

Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

Dissimilar welding of nickel-based Alloy 690 to SUS 304L with Ti addition

NASA Astrophysics Data System (ADS)

Lee, H. T.; Jeng, S. L.; Yen, C. H.; Kuo, T. Y.

2004-10-01

This study investigates the effects of Ti addition on the weldability, microstructure and mechanical properties of a dissimilar weldment of Alloy 690 and SUS 304L. Shielding metal arc welding (SMAW) is employed to butt-weld two plates with three welding layers, where each layer is deposited in a single pass. To investigate the effects of Ti addition, the flux coatings of the electrodes used in the welding process are modified by varying additions of either a Ti-Fe compound or a Ti powder. The results indicate that the microstructure of the fusion zone (FZ) is primarily dendritic. With increasing Ti content, it is noted that the microstructure changes from a columnar dendritic to an equiaxed dendritic, in which the primary dendrite arm spacing (PDAS) becomes shorter. Furthermore, it is observed that the amount of Al-Ti oxide phase increases in the inter-dendritic region, while the amount of Nb-rich phase decreases. Moreover, the average hardness of the FZ increases slightly. The results indicate that Ti addition prompts a significant increase in the elongation of the weldment (i.e. 36.5%, Ti: 0.41 wt%), although the tensile strength remains relatively unchanged. However, at an increased Ti content of 0.91 wt%, an obvious reduction in the tensile strength is noted, which can be attributed to a general reduction in the weldability of the joint.

Local geometric and electronic structures and origin of magnetism in Co-doped BaTiO3 multiferroics

NASA Astrophysics Data System (ADS)

Phan, The-Long; Thang, P. D.; Ho, T. A.; Manh, T. V.; Thanh, Tran Dang; Lam, V. D.; Dang, N. T.; Yu, S. C.

2015-05-01

We have prepared polycrystalline samples BaTi1-xCoxO3 (x = 0-0.1) by solid-state reaction. X-ray diffraction and Raman-scattering studies reveal the phase separation in crystal structure as changing Co-doping content (x). The samples with x = 0-0.01 are single phase in a tetragonal structure. At higher doping contents (x > 0.01), there is the formation and development of a secondary hexagonal phase. Magnetization measurements at room temperature indicate a coexistence of paramagnetic and weak-ferromagnetic behaviors in BaTi1-xCoxO3 samples with x > 0, while pure BaTiO3 is diamagnetic. Both these properties increase with increasing x. Analyses of X-ray absorption spectra recorded from BaTi1-xCoxO3 for the Co and Ti K-edges indicate the presence of Co2+ and Co3+ ions. They locate in the Ti4+ site of the tetragonal and hexagonal BaTiO3 structures. Particularly, there is a shift of oxidation state from Co2+ to Co3+ when Co-doping content increases. We believe that the paramagnetic nature in BaTi1-xCoxO3 samples is due to isolated Co2+ and Co3+ centers. The addition of Co3+ ions enhances the paramagnetic behavior. Meanwhile, the origin of ferromagnetism is due to lattice defects, which is less influenced by the changes caused by the variation in concentration of Co2+ and Co3+ ions.

[Toxic effects of nano-TiO2 on Gymnodinium breve].

PubMed

Li, Feng-Min; Zhao, Wei; Li, Yuan-Yuan; Tian, Zhi-Jia; Wang, Zhen-Yu

2012-01-01

In order to reveal the toxicity and mechanism of nano-TiO2 on algae, the inhibition effect, enzyme activity, oxygen free radicals of nano-TiO2 on the growth of G. breve were investigated. The results showed that G. breve was inhibited by nano-TiO2, and the 72 h-EC50 was 9.7 mg x L(-1). With the increasing concentration of nano-titanium dioxide, the activities of SOD decrease significantly (P < 0.05). The content of hydrogen peroxide radicals and the activities of CAT increase significantly (P < 0.05), and the content of superoxide anion shows the increasing trend. The content of hydrogen peroxide radicals was 0.083 U x mL(-1) in 0 mg x L(-1) nano-TiO2 suspension while that was 1.1 U x mL(-1) in control after 48 h. Through the study of 20 mg x L(-1) nano-titanium dioxide on G. breve at different times, the activities of SOD and CAT, the content of MDA are consistent, which the highest values is achieved at the exposure time of 12 hours and the lowest value is found at the exposure time of 48 hours. The content of hydroxyl radical increased significantly at the exposure time of 48 hours. The activity of SOD was 0.14 U x (10(7) cell x min)(-1) in G. breve at 12 h which was ten times higher than that at 48 h.

Development and characterization of the kefiran-whey protein isolate-TiO2 nanocomposite films.

PubMed

Zolfi, Mohsen; Khodaiyan, Faramarz; Mousavi, Mohammad; Hashemi, Maryam

2014-04-01

Biodegradable kefiran-whey protein isolate (WPI)-titanium dioxide (TiO2) blend films were developed and characterized as a function of incorporating amount of TiO2 nanoparticles (1, 3 and 5% wt.). Results showed that the water vapor permeability, moisture content, moisture absorption and water solubility decreased by increasing the nano-TiO2 content. Mechanical tests revealed the plasticizing effect of TiO2 nanoparticles on the kefiran-WPI-TiO2 film. Addition of TiO2 nanoparticles to kefiran-WPI films significantly decreased tensile strength and Young's modulus, while increased its elongation at break. Differential scanning calorimetry data indicated that the glass transition temperature significantly changed by adding nano-TiO2. X-ray diffraction analysis also demonstrated that crystal type in kefiran-WPI was not affected by incorporation of TiO2 nanoparticles. A uniform distribution at 1 and 3% wt. loading levels of TiO2 nanoparticles was observed using scanning electron microscopy (SEM) micrographs. Copyright © 2014 Elsevier B.V. All rights reserved.

The influence of water and redox conditions on the seismic properties of olivine

NASA Astrophysics Data System (ADS)

Cline, C. J., II; Jackson, I.; Faul, U.; David, E. C.; Berry, A.

2017-12-01

Eight polycrystalline olivine specimens of both synthetic (solution-gelation derived) and natural (San Carlos) origins were fabricated by hot-pressing at 1200°C and 300 MPa. Amongst these specimens, six contained varying concentrations of Ti, allowing control of hydroxyl (or `water') content through the creation of the energetically favored Ti-clinohumite-like defect (doubly protonated Si vacancy associated with a Ti/Mg substitution). Along with a Ti-free Fo90 specimen, these materials have Ti contents ranging between 0 and 802 atom ppm Ti/Si and associated chemically bound `water' contents between 0 and 1150 atom ppm H/Si, along with molecular water concentrations between 0 and 245 atom ppm H/Si. Each hot-pressed specimen was then subsequently wrapped in Pt, Ni or NiFe foil to control oxygen fugacity (fO2), and interrogated under water-undersaturated conditions via forced torsional oscillation. Testing was conducted at seismic periods of 1 - 1000 s and 200 MPa confining pressure during slow staged cooling from 1200 to 25°C. All specimens, regardless of water content or metal sleeving, exhibit high temperature background behavior, involving monotonically increasing levels of dissipation and concomitantly decreasing shear modulus with increasing oscillation period and increasing temperature. Our experimental results demonstrate unambiguously that water content (and water fugacity) has a negligible effect on the measured seismic properties olivine. Rather, a relationship between the prevailing redox conditions set by the metal sleeving and the magnitude of anelastic relaxation was observed. These results suggest that low velocity and high attenuation anomalies in the upper mantle are not due to elevated water contents. Instead, in oxidized and hydrous regions above subducting slabs and perhaps in the oceanic asthenosphere, high attenuation may reflect elevated fO2 conditions.

Toxicological effects of nanometer titanium dioxide (nano-TiO2) on Chlamydomonas reinhardtii.

PubMed

Chen, Lanzhou; Zhou, Lina; Liu, Yongding; Deng, Songqiang; Wu, Hao; Wang, Gaohong

2012-10-01

The toxicological effects of nanometer titanium dioxide (nano-TiO2) on a unicellular green alga Chlamydomonas reinhardtii were assessed by investigating the changes of the physiology and cyto-ultrastructure of this species under treatment. We found that nano-TiO2 inhibited photosynthetic efficiency and cell growth, but the content of chlorophyll a content in algae did not change, while carotenoid and chlorophyll b contents increased. Malondialdehyde (MDA) content reached maximum values after 8h exposure and then decreased to a moderately low level at 72 h. Electron microscopy images indicated that as concentrations of nano-TiO2 increased, a large number of C. reinhardtii cells were noted to be damaged: the number of chloroplasts declined, various other organelles were degraded, plasmolysis occurred, and TiO2 nanoparticles were found to be located inside cell wall and membrane. It was also noted that cell surface was surrounded by TiO2 particles, which could present an obstacle to the exchange of substances between the cell and its surrounding environment. To sum up, the effect of nano-TiO2 on C. reinhardtii included cell surface aggregation, photosynthesis inhibition, lipid peroxidation and new protein synthesis, while the response of C. reinhardtii to nano-TiO2 was a rapid process which occurs during 24 h after exposing and may relate to physiological stress system to mitigate damage. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

Optimization of mechanical properties, biocorrosion properties and antibacterial properties of as-cast Ti-Cu alloys.

PubMed

Zhang, Erlin; Ren, Jing; Li, Shengyi; Yang, Lei; Qin, Gaowu

2016-10-21

Ti-Cu sintered alloys have shown good antibacterial abilities. However, the sintered method (powder metallurgy) is not convenient to produce devices with a complex structure. In this paper, Ti-Cu alloys with 2.0, 3.0 and 4.0 wt.% Cu were prepared in an arc melting furnace and subjected to different heat treatments: solid solution and ageing, to explore the possibility of preparing an antibacterial Ti-Cu alloy by a casting method and to examine the effect of Cu content. Phase identification was conducted on an XRD diffraction meter, and the microstructure was observed by a metallographic microscope, a scanning electron microscope (SEM) with energy disperse spectroscopy (EDS) and transmission electron microscopy (TEM). Microhardness and the compressive property of Ti-Cu alloys were tested, and the corrosion resistance and antibacterial activity were assessed in order to investigate the effect of the Cu content. Results showed that the as-cast Ti-Cu alloys exhibited a very low antibacterial rate against Staphylococcus aureus (S. aureus). Heat treatment improved the antibacterial rate significantly, especially after a solid and ageing treatment (T6). Antibacterial rates as high as 90.33% and 92.57% were observed on Ti-3Cu alloy and Ti-4Cu alloy, respectively. The hardness, the compressive yield strength, the anticorrosion resistance and the antibacterial rate of Ti-Cu alloys increased with an increase of Cu content in all conditions. It was demonstrated that homogeneous distribution and a fine Ti 2 Cu phase played a very important role in the mechanical property, anticorrosion and antibacterial properties. Furthermore, it should be pointed out that the Cu content should be at least 3 wt.% to obtain good antibacterial properties (>90% antibacterial rate) as well as satisfactory mechanical properties.

Cell Structure Evolution of Aluminum Foams Under Reduced Pressure Foaming

NASA Astrophysics Data System (ADS)

Cao, Zhuokun; Yu, Yang; Li, Min; Luo, Hongjie

2016-09-01

Ti-H particles are used to increase the gas content in aluminum melts for reduced pressure foaming. This paper reports on the RPF process of AlCa alloy by adding TiH2, but in smaller amounts compared to traditional process. TiH2 is completely decomposed by stirring the melt, following which reduced pressure is applied. TiH2 is not added as the blowing agent; instead, it is added for increasing the H2 concentration in the liquid AlCa melt. It is shown that pressure change induces further release of hydrogen from Ti phase. It is also found that foam collapse is caused by the fast bubble coalescing during pressure reducing procedure, and the instability of liquid film is related to the significant increase in critical thickness of film rupture. A combination of lower amounts of TiH2, coupled with reduced pressure, is another way of increasing hydrogen content in the liquid aluminum. A key benefit of this process is that it provides time to transfer the molten metal to a mold and then apply the reduced pressure to produce net shape foam parts.

Effect of Sputtering Current on the Comprehensive Properties of (Ti,Al)N Coating and High-Speed Steel Substrate

NASA Astrophysics Data System (ADS)

Su, Yongyao; Tian, Liangliang; Hu, Rong; Liu, Hongdong; Feng, Tong; Wang, Jinbiao

2018-05-01

To improve the practical property of (Ti,Al)N coating on a high-speed steel (HSS) substrate, a series of sputtering currents were used to obtain several (Ti,Al)N coatings using a magnetron sputtering equipment. The phase structure, morphology, and components of (Ti,Al)N coatings were characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy, respectively. The performance of (Ti,Al)N coatings, adhesion, hardness, and wear resistance was tested using a scratch tester, micro/nanohardness tester, and tribometer, respectively. Based on the structure-property relationships of (Ti,Al)N coatings, the results show that both the Al content and deposition temperature of (Ti,Al)N coatings increased with sputtering current. A high Al content helped to improve the performance of (Ti,Al)N coatings. However, the HSS substrate was softened during the high sputtering current treatment. Therefore, the optimum sputtering current was determined as 2.5 A that effectively increased the hardness and wear resistance of (Ti,Al)N coating.

Microstructure and Room-Temperature Mechanical Properties of FeCrMoVTi x High-Entropy Alloys

NASA Astrophysics Data System (ADS)

Guo, Jun; Huang, Xuefei; Huang, Weigang

2017-07-01

FeCrMoVTi x ( x values represent the molar ratio, where x = 0, 0.5, 1.0, 1.5, and 2.0) high-entropy alloys were prepared by a vacuum arc melting method. The effects of Ti element on the microstructure and room-temperature mechanical properties of the as-cast FeCrMoVTi x alloys were investigated. The results show that the prepared alloys exhibited typical dendritic microstructure and the size of the microstructure became fine with increasing Ti content. The FeCrMoV alloy exhibited a single body-centered cubic structure (BCC1) and the alloys prepared with Ti element exhibited BCC1 + BCC2 mixed structure. The new BCC2 phase is considered as (Fe, Ti)-rich phase and was distributed in the dendrite region. With the increase of Ti content, the volume fraction of the BCC2 phase increased and its shape changed from a long strip to a network. For the FeCrMoV alloy, the fracture strength, plastic strain, and hardness reached as high as 2231 MPa, 28.2%, and 720 HV, respectively. The maximum hardness of 887 HV was obtained in the FeCrMoVTi alloy. However, the fracture strength, yield stress, and plastic strain of the alloys decreased continuously as Ti content increased. In the room-temperature compressive test, the alloys showed typical brittle fracture characteristics.

Effects of Si content on microstructure and mechanical properties of TiAlN/Si3N4-Cu nanocomposite coatings

NASA Astrophysics Data System (ADS)

Feng, Changjie; Hu, Shuilian; Jiang, Yuanfei; Wu, Namei; Li, Mingsheng; Xin, Li; Zhu, Shenglong; Wang, Fuhui

2014-11-01

TiAlN/Si3N4-Cu nanocomposite coatings of various Si content (0-5.09 at.%) were deposited on AISI-304 stainless steel by DC reactive magnetron sputtering technique. The chemical composition, microstructure, mechanical and tribological properties of these coatings were systematically investigated by means of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), nanoindentation tester, a home-made indentation system, a scratch tester and a wear tester. Results indicated that with increasing Si content in these coatings, a reduction of grain size and surface roughness, a transformation of the (1 1 1) preferred orientation was detected by XRD and FESEM. Furthermore the hardness of these coatings increase from 9.672 GPa to 18.628 GPa, and the elastic modulus reveal the rising trend that increase from 224.654 GPa to 251.933 GPa. However, the elastic modulus of TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content dropped rapidly and changed to about 180.775 GPa. The H3/E2 ratio is proportional to the film resistance to plastic deformation. The H3/E2 ratio of the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content possess of the maximum of 0.11 GPa, and the indentation test indicate that few and fine cracks were observed from its indentation morphologies. The growth pattern of cracks is mainly bending growing. The present results show that the best toughness is obtained for TiAlN/Si3N4-Cu nanocomposite coating containing 3.39 at.% Si content. In addition, the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content also has good adhesion property and superior wear resistance, and the wear mechanism is mainly adhesion wear.

First-principles calculation of the structure and electronic properties of Fe-substituted Bi2Ti2O7

NASA Astrophysics Data System (ADS)

Huang, Jin-Dou; Zhang, Zhenyi; Lin, Feng; Dong, Bin

2017-12-01

We performed first-principles calculations to investigate the formation energy, geometry structure, and electronic property of Fe-doped Bi2Ti2O7 systems with different Fe doping content. The calculated formation energies indicate that the substitutional configurations of Fe-doping Bi2Ti2O7 are easy to obtain under O-rich growth condition, but their thermodynamic stability decreases with the increase of Fe content. The calculated spin-resolved density of states and band structures indicate that the introduction of Fe into Bi2Ti2O7 brings high spin polarization. The spin-down impurity levels in Fe x Bi2-x Ti2O7 and spin-up impurity levels in Fe x Bi2Ti2-x O7 systems locate in the bottom of conduction band and narrow the band gap significantly, thus leading to the absorption of visible light. Interestingly, the impurity states in Fe x Bi2-x Ti2O7 are the efficient separation center of photogenerated electron and hole, and less affected by Fe doping content, in comparison, the levels of impurity band in Fe x Bi2Ti2-x O7 systems are largely effected by the Fe doping content, and high Fe doping content is the key factor to improve the separating rate of photogenerated electron and hole.

Synthesis of TiCr2 intermetallic compound from mechanically activated starting powders via calcio-thermic co-reduction

NASA Astrophysics Data System (ADS)

Bayat, O.; Khavandi, A. R.; Ghasemzadeh, R.

2017-05-01

Effect of mechanical activation of TiO2 and Cr2O3 oxides as starting materials was investigated for direct synthesis of TiCr2. Differential thermal analysis (DTA) indicated that increasing the ball milling time resulted in lower exothermic reaction temperatures between molten Ca-Cr2O3 and molten Ca-TiO2. A model-free Kissinger type method was applied to DTA data to evaluate the reaction kinetics. The results reveal that the activation energy of the exothermic reactions decreased with increasing the milling time. The structure, oxygen content, and average particle sizes of the obtained TiCr2 product were affected by the ball milling time of the starting materials. Increasing the milling time from 10 to 40 h decreased the average particle size and oxygen content of the obtained TiCr2 from 10 to 2 μm and from 1690 to 1290 ppm, respectively. The X-ray diffraction (XRD) results showed that TiCr2 compounds with metastable bcc phase can be produced using nano-sized starting materials, while only a slight amount of bcc phase can be obtained in the TiCr2 compounds, using micron-sized starting materials. The TiCr2 obtained by this method had a hydrogen absorption capability of 0.63 wt % and the kinetics of the hydrogen absorption increased for the 40 h milled sample.

Investigations on structural, elastic, thermodynamic and electronic properties of TiN, Ti2N and Ti3N2 under high pressure by first-principles

NASA Astrophysics Data System (ADS)

Yang, Ruike; Zhu, Chuanshuai; Wei, Qun; Du, Zheng

2016-11-01

The lattice parameters, cell volume, elastic constants, bulk modulus, shear modulus, Young's modulus and Poisson's ratio are calculated at zero pressure, and their values are in excellent agreement with the available data, for TiN, Ti2N and Ti3N2. By using the elastic stability criteria, it is shown that the three structures are all stable. The brittle/ductile behaviors are assessed in the pressures from 0 GPa to 50 GPa. Our calculations present that the performances for TiN, Ti2N and Ti3N2 become from brittle to ductile with pressure rise. The Debye temperature rises as pressure increase. With increasing N content, the enhancement of covalent interactions and decline of metallicity lead to the increase of the micro-hardness. Their constant volume heat capacities increase rapidly in the lower temperature, at a given pressure. At higher temperature, the heat capacities are close to the Dulong-Petit limit, and the heat capacities of TiN and Ti2N are larger than that of c-BN. The thermal expansion coefficients of titanium nitrides are slightly larger than that of c-BN. The band structure and the total Density of States (DOS) are calculated at 0 GPa and 50 GPa. The results show that TiN and Ti2N present metallic character. Ti3N2 present semiconducting character. The band structures have some discrepancies between 0 GPa and 50 GPa. The extent of energy dispersion increases slightly at 50 GPa, which means that the itinerant character of electrons becomes stronger at 50 GPa. The main bonding peaks of TiN, Ti2N and Ti3N2 locate in the range from -10 to 10 eV, which originate from the contribution of valance electron numbers of Ti s, Ti p, Ti d, N s and N p orbits. We can also find that the pressure makes that the total DOS decrease at the Fermi level for Ti2N. The bonding behavior of N-Ti compounds is a combination of covalent and ionic nature. As N content increases, valence band broadens, valence electron concentration increases, and covalent interactions become stronger. This is reflected in shortening of Ti-N bonds.

Effect of Cu content on microstructure, mechanical and anti-fouling properties of TiSiN-Cu coating deposited by multi-arc ion plating

NASA Astrophysics Data System (ADS)

Bai, Xuebing; Li, Jinlong; Zhu, Lihui; Wang, Liping

2018-01-01

The copper-doped TiSiN coatings were deposited on 316L stainless steel by reactive co-sputtering in multi-arc ion plating. The surface morphology and structure of the coating were analyzed by scanning electron microcopies, X-ray diffraction and X-ray photoelectron spectroscopy. The hardness was tested using Nano-indentation. The influence of the copper content in the coatings on the structure and mechanical properties of TiSiN-Cu coatings was investigated. Antifouling behaviors of the coatings were evaluated by analyzing adhesion and propagation of P. tricornutum, N. closterium, and Chlorella sp. The TiSiN-Cu coatings had a unique structure of amorphous Si3N4 and nanocrystalline nc-TiN/nc-Cu. The Cu-TiSiN coatings can inhibit effectively attachment and colonization of the algae on the surface. When the copper content increases from 6.75 at.% to 25.15 at.%, the coatings show an obvious decrease in hardness, significantly increase in the surface roughness and greatly weaken in antifouling properties. When the copper content is 6.75 at.%, the coating has the highest hardness with 30 GPa, and the best reduction ratio with 89%, 93% and 57% attachment of P. triceratium, N. closterium and Chlorella sp., respectively. The TiSiN-Cu coating with a copper dosage of 6.75 at.% has the excellent mechanical properties and capability of killing effectively microalgae.

Ti-Nb thin films deposited by magnetron sputtering on stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzalez, E. David; Niemeyer, Terlize C.; Afonso, Conrado R. M.

2016-03-15

Thin films of Ti-Nb alloys were deposited on AISI 316L stainless steel substrate by magnetron sputtering, and the structure, composition, morphology, and microstructure of the films were analyzed by means of x-ray diffraction (XRD), (scanning) transmission electron microscopy (TEM) coupled with energy-dispersive x-ray spectroscopy, atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Thin films of four compositions were produced: Ti{sub 85}Nb{sub 15} (Ti-26 wt. % Nb), Ti{sub 80}Nb{sub 20} (Ti-33 wt. % Nb), Ti{sub 70}Nb{sub 30} (Ti-45 wt. % Nb), and Ti{sub 60}Nb{sub 40} (Ti-56 wt. % Nb). Structural characterization by XRD indicated that only the β phase was present in the thinmore » films and that the increase in the Nb content modified the alloy film texture. These changes in the film texture, also detected by TEM analysis, were attributed to different growth modes related to the Nb content in the alloy films. The mean grain sizes measured by AFM increased with the Nb amount (from 197 to 222 nm). XPS analysis showed a predominance of oxidized Ti and Nb on the film surfaces and an enrichment of Ti.« less

Surface phenomena of hydroxyapatite film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants.

PubMed

Kim, Eun-Ju; Jeong, Yong-Hoon; Choe, Han-Cheol

2013-03-01

In this study, surface phenomena of hydroxyapatite (HA) film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants have been investigated by electron beam physical vapor deposition (EB-PVD), field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), potentiostat and contact angle. The microstructure of Ti-29Nb-xZr alloys exhibited equiaxed structure and alpha" phase decreased, whereas beta phase increased as Zr content increased. The increment of Zr contents in HA coated nanotubular Ti-29Nb-xZr alloys showed good corrosion potential in 0.9% NaCI solution. The wettability of HA coated nanotubular surface was higher than that of non-coated samples.

Formation of thick stratiform Fe-Ti oxide layers in layered intrusion and frequent replenishment of fractionated mafic magma: Evidence from the Panzhihua intrusion, SW China

NASA Astrophysics Data System (ADS)

Song, Xie-Yan; Qi, Hua-Wen; Hu, Rui-Zhong; Chen, Lie-Meng; Yu, Song-Yue; Zhang, Jia-Fei

2013-03-01

Panzhihua intrusion is one of the largest layered intrusions that hosts huge stratiform Fe-Ti oxide layers in the central part of the Emeishan large igneous province, SW China. Up to 60 m thick stratiform massive Fe-Ti oxide layers containing 85 modal% of magnetite and ilmenite and overlying magnetite gabbro compose cyclic units of the Lower Zone of the intrusion. The cyclic units of the Middle Zone consist of magnetite gabbro and overlying gabbro. In these cyclic units, contents of Fe2O3(t), TiO2 and Cr and Fe3+/Ti4+ ratio of the rocks decrease upward, Cr content of magnetite and forsterite percentage of olivine decrease as well. The Upper Zone consists of apatite gabbro characterized by enrichment of incompatible elements (e.g., 12-18 ppm La, 20-28 ppm Y) and increasing of Fe3+/Ti4+ ratio (from 1.3 to 2.3) upward. These features indicate that the Panzhihua intrusion was repeatedly recharged by more primitive magma and evolved magmas had been extracted. Calculations using MELTS indicate that extensive fractionation of olivine and clinopyroxene in deep level resulted in increasing Fe and Ti contents in the magma. When these Fe-Ti-enriched magmas were emplaced along the base of the Panzhihua intrusion, Fe-Ti oxides became an early crystallization phase, leading to a residual magma of lower density. We propose that the unusually thick stratiform Fe-Ti oxide layers resulted from coupling of gravity settling and sorting of the crystallized Fe-Ti oxides from Fe-Ti-enriched magmas and frequent magma replenishment along the floor of the magma chamber.

Change in silica sources in Roman and post-Roman glass

NASA Astrophysics Data System (ADS)

Aerts, A.; Velde, B.; Janssens, K.; Dijkman, W.

2003-04-01

Although Roman and post-Empire glasses found in Europe are reputed to have a very constant composition and hence source of components, it appears that some 4-5th century and later specimens show evidence of a different source of silica (sand) component. Zirconium and titanium are the discriminating elements. Data presented here for 278 specimens from 1st to 4th century German and Belgian samples indicate a strongly homogeneous Zr and Ti content; N: number of analyzed samples while 62 samples from Maastricht show low Zr-Ti contents from 1st to 3rd century samples while 4-5th century samples show a strong trend of concomitant Ti and Zr increase. If the high values of Zr-Ti represent a new source of silica (sand) the trend from low to high content suggests that a significant amount of low Zr-Ti glass was recycled to form these glass objects. Similar high Ti content can be seen in analysis results reported for other but not all 4-5th century samples found in northern Europe while earlier productions show typical low Ti contents. Although the fusing agent for these glasses seems to have always been natron (a mineral deposit in the Nile delta) from Hellenistic times to the 9th century, a change in the silica source, indicated by variation of the Ti and Zr content, could very well reflect the results of political instability of the 4-5th century exemplified by the fragmentation of the Roman Empire into two parts.

Antibacterial activity of DLC films containing TiO2 nanoparticles.

PubMed

Marciano, F R; Lima-Oliveira, D A; Da-Silva, N S; Diniz, A V; Corat, E J; Trava-Airoldi, V J

2009-12-01

Diamond-like carbon (DLC) films have been the focus of extensive research in recent years due to their potential applications as surface coatings on biomedical devices. Titanium dioxide (TiO2) in the anatase crystalline form is a strong bactericidal agent when exposed to near-UV light. In this work we investigate the bactericidal activity of DLC films containing TiO2 nanoparticles. The films were grown on 316L stainless-steel substrates from a dispersion of TiO2 in hexane using plasma-enhanced chemical vapor deposition. The composition, bonding structure, surface energy, stress, and surface roughness of these films were also evaluated. The antibacterial tests were performed against Escherichia coli (E. coli) and the results were compared to the bacterial adhesion force to the studied surfaces. The presence of TiO2 in DLC bulk was confirmed by Raman spectroscopy. As TiO2 content increased, I(D)/I(G) ratio, hydrogen content, and roughness also increased; the films became more hydrophilic, with higher surface free energy and the interfacial energy of bacteria adhesion decreased. Experimental results show that TiO2 increased DLC bactericidal activity. Pure DLC films were thermodynamically unfavorable to bacterial adhesion. However, the chemical interaction between the E. coli and the studied films increased for the films with higher TiO2 concentration. As TiO2 bactericidal activity starts its action by oxidative damage to the bacteria wall, a decrease in the interfacial energy of bacteria adhesion causes an increase in the chemical interaction between E. coli and the films, which is an additional factor for the increasing bactericidal activity. From these results, DLC with TiO2 nanoparticles can be useful for producing coatings with antibacterial properties.

Effect of silver-doping on the crystal structure, morphology and photocatalytic activity of TiO2 nanofibers

NASA Astrophysics Data System (ADS)

Barakat, N. A. M.; Kim, H. Y.

2012-09-01

In this study, effect of sliver-doping on the crystal structure, the nanofibrous morphology and the photocatalytic activity of titanium oxide nanofibers have been investigated. Silver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600 °C. The results affirmed formation of silver-doped TiO2 nanofibers composed of anatase and rutile when the silver nitrate content in the original electrospun solution was more than 3 wt%. The rutile phase content was directly proportional with the AgNO3 concentration in the electrospun solution. Negative impact of the silver-doping on the nanofibrous morphology was observed as increase the silver content caused to decrease the aspect ratio, i.e. producing nanorods rather nanofibers. However, silver-doping leads to modify the surface roughness. Study of the photocatalytic degradation of methylene blue dye clarified that increase the silver content strongly enhances the dye oxidation process.

Ti(3+) in meteoritic and synthetic hibonite

NASA Technical Reports Server (NTRS)

Beckett, John R.; Stolper, Edward; Live, David; Tsay, Fun-Dow; Grossman, Lawrence

1988-01-01

This paper describes the first direct determination (performed by electron spin resonance spectroscopy) of Ti(3+) in hibonite from inclusion SH-7 of the Murchison C2 chondrite and in synthetic hibonites of four compositions, three of which corresponded to the compositions of blue hibonites and one to that of an orange hibonite. The Ti(3+) concentration in the hibonite from SH-7 was found to range from 0.35 to 0.44 percent, while the Ti(3+) contents in three synthetic blue hibonites ranged from 0.02 to 0.64 percent. Orange hibonite contained no Ti(3+), supporting an earlier conclusion that the orange-to-blue transition is associated with the presence of Ti(3+). At constant temperature and oxygen fugacity, the Ti(3+)/Ti(4+) ratio in synthetic hibonites was found to increase with decreasing V, but was not strongly dependent on bulk Ti. Fe and Cr contents did not have a significant effect on the amount of Ti(3+).

Ti(3+) in meteoritic and synthetic hibonite

NASA Astrophysics Data System (ADS)

Beckett, John R.; Live, David; Tsay, Fun-Dow; Grossman, Lawrence; Stolper, Edward

1988-06-01

This paper describes the first direct determination (performed by electron spin resonance spectroscopy) of Ti(3+) in hibonite from inclusion SH-7 of the Murchison C2 chondrite and in synthetic hibonites of four compositions, three of which corresponded to the compositions of blue hibonites and one to that of an orange hibonite. The Ti(3+) concentration in the hibonite from SH-7 was found to range from 0.35 to 0.44 percent, while the Ti(3+) contents in three synthetic blue hibonites ranged from 0.02 to 0.64 percent. Orange hibonite contained no Ti(3+), supporting an earlier conclusion that the orange-to-blue transition is associated with the presence of Ti(3+). At constant temperature and oxygen fugacity, the Ti(3+)/Ti(4+) ratio in synthetic hibonites was found to increase with decreasing V, but was not strongly dependent on bulk Ti. Fe and Cr contents did not have a significant effect on the amount of Ti(3+).

The Effect of Mo Particles Addition in Ag-Cu-Ti Filler Alloy on Ti(C,N)-Based Cermet/45 Steel-Brazed Joints

NASA Astrophysics Data System (ADS)

He, Hu; Du, Xueming; Huang, Xiaokai; Xu, Weijian; Yao, Zhenhua

2018-05-01

Reliable brazing of Ti(C,N)-based cermet and 45 steel was successfully achieved by using the Mo-particle-reinforced Ag-Cu-Ti composite filler. The effects of Mo content on the interfacial microstructure and mechanical properties of Ti(C,N)-based cermet/45 steel joints were analyzed. The results showed that the joint microstructure was primarily composed of Ni3Ti+Cu3Ti2, Ag(s,s)+Cu(s.s), CuTi+Mo, Ti-based solid solution, and FeTi+Fe2Ti. With the increase in Mo content in filler, the thickness of the Ni3Ti+Cu3Ti2 layer adjacent to the Ti(C,N)-based cermet decreases, while more blocky Ti-Cu intermetallic were observed in the brazing seam. The shear strength of the joint could be significantly improved by adding suitable amounts of Mo into the Ag-Cu-Ti filler, and the peak value of 263 MPa was achieved when the alloys were brazed with Ag-Cu-Ti+8wt.%Mo composite filler at 920 °C for 20 min.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samsonov, G. V.; Vitryanyuk, V. K.; Voronkin, M. A.

Physicomechanical properties of the hard alloy TiC -Ni--Mo (with content 3. 5, 10, and 25 mol.% relative to TiC) were studied as affected by its carbide phase alloying with niobium carbide. It is shown that an increase in the NbC content favors a rise in the bending strength to 132 kg/mm/sup 2/ and impact strength at practically unchanged hardness (91 HR.4), which is explained by some rise in the grain plasticity of the solid phase presenting the complex carbide TiC -NbC.

New high pressure experiments on sulfide saturation of high-FeO∗ basalts with variable TiO2 contents - Implications for the sulfur inventory of the lunar interior

NASA Astrophysics Data System (ADS)

Ding, Shuo; Hough, Taylor; Dasgupta, Rajdeep

2018-02-01

In order to constrain sulfur concentration in intermediate to high-Ti mare basalts at sulfide saturation (SCSS), we experimentally equilibrated FeS melt and basaltic melt using a piston cylinder at 1.0-2.5 GPa and 1400-1600 °C, with two silicate compositions similar to high-Ti (Apollo 11: A11, ∼11.1 wt.% TiO2, 19.1 wt.% FeO∗, and 39.6 wt.% SiO2) and intermediate-Ti (Luna 16, ∼5 wt.% TiO2, 18.7 wt.% FeO∗, and 43.8 wt.% SiO2) mare basalts. Our experimental results show that SCSS increases with increasing temperature, and decreases with increasing pressure, which are similar to the results from previous experimental studies. SCSS in the A11 melt is systematically higher than that in the Luna 16 melt, which is likely due to higher FeO∗, and lower SiO2 and Al2O3 concentration in the former. Compared to the previously constructed SCSS models, including those designed for high-FeO∗ basalts, the SCSS values determined in this study are generally lower than the predicted values, with overprediction increasing with increasing melt TiO2 content. We attribute this to the lower SiO2 and Al2O3 concentration of the lunar magmas, which is beyond the calibration range of previous SCSS models, and also more abundant FeTiO3 complexes in our experimental melts that have higher TiO2 contents than previous models' calibration range. The formation of FeTiO3 complexes lowers the activity of FeO∗, a FeO∗silicatemelt , and therefore causes SCSS to decrease. To accommodate the unique lunar compositions, we have fitted a new SCSS model for basaltic melts of >5 wt.% FeO∗ and variable TiO2 contents. Using previous chalcophile element partitioning experiments that contained more complex Fe-Ni-S sulfide melts, we also derived an empirical correction that allows SCSS calculation for basalts where the equilibrium sulfides contain variable Ni contents of 10-50 wt.%. At the pressures and temperatures of multiple saturation points, SCSS of lunar magmas with compositions from picritic glasses, mare basalts, to young lunar meteorites vary from 2600 to 4800 ppm for basalt equilibration with a pure FeS melt and from 1400 to 2600 ppm for basalt equilibration with a Fe-rich sulfide melt containing 30 wt.% Ni. The measured S contents in these proposed near-primary lunar magmas are lower than the predicted SCSS at the conditions of their last equilibration with the lunar mantle, indicating no sulfide retention in the lunar mantle source during partial melting. Sulfide exhaustion during partial melting in the lunar mantle also supports the notion that the bulk silicate moon is depleted in highly siderophile elements. Based on the measured S contents and the estimated degree of melting, the estimated S contents for the mantle source of A15 green glass and A15 mare basalts is 10-23 ppm; for A17 orange glass is 25-62 ppm, for A12 mare basalts is 27-92 ppm, and for A11 basalt is 35-120 ppm. Consideration of SCSS decrease due to the presence of Ni in the sulfide melt does not change these mantle S abundance estimates for <30 wt.% Ni in the sulfide. The inferred S contents suggest that the lunar mantle is heterogeneous in terms of S. Although variable among different groups, the inferred S abundance of up to 120 ppm in the lunar mantle falls near the lower end of the S content of the depleted terrestrial mantle such as the MORB source.

Synthesis of TiCx Powder via the Underwater Explosion of an Explosive

NASA Astrophysics Data System (ADS)

Tanaka, Shigeru; Bataev, Ivan; Hamashima, Hideki; Tsurui, Akihiko; Hokamoto, Kazuyuki

2018-05-01

In this study, a novel approach to the explosive synthesis of titanium carbide (TiC) is discussed. Nonstoichiometric TiCx powder was produced via the underwater explosion of a Ti powder encapsulated within a spherical explosive charge. The explosion process, bubble formation, and synthesis process were visualized using high-speed camera imaging. It was concluded that synthesis occurred within the detonation gas during the first expansion/contraction cycle of the bubble, which was accompanied by a strong emission of light. The recovered powders were studied using scanning electron microscopy and X-ray diffraction. Submicron particles were generated during the explosion. An increase in the carbon content of the starting powder resulted in an increase in the carbon content of the final product. No oxide byproducts were observed within the recovered powders.

Thermodynamic evaluation of oxygen behavior in Ti powder deoxidized by Ca reductant

NASA Astrophysics Data System (ADS)

Kim, Sun-Joong; Oh, Jung-Min; Lim, Jae-Won

2016-07-01

To produce low oxygen Ti powder of less than 1000 mass ppm, commercial Ti powder was deoxidized by two types of Ca reductants: a solid Ca and a Ca vapor. Compared with the iso-oxygen partial pressure in the Ti-O binary phase diagram, the PO2 in the raw Ti powder increased with temperature compared to the reduction reaction of Ca. Therefore, the O2 content in the Ti powder decreased as the deoxidation temperature increased from 873 K, showing a local minima at 1273 K. The oxygen concentration at 1373 K was greater than that at 1273 K because the oxygen solubility of the Ti powder was increased by the equilibrium relation between Ca and CaO. On the basis of the thermodynamic assessment, the deoxidation of Ti powder can be improved by increasing the temperature and lowering the oxygen solubility with the saturation of CaO.

Impedance spectroscopy of V2O5-Bi2O3-BaTiO3 glass-ceramics

NASA Astrophysics Data System (ADS)

Al-syadi, Aref M.; Yousef, El Sayed; El-Desoky, M. M.; Al-Assiri, M. S.

2013-12-01

The glasses within composition as: (80 - x)V2O5/20Bi2O3/xBaTiO3 with x = 2.5, 5, 7.5 and 10 mol% have been prepared. The glass transition (Tg) increases with increasing BaTiO3 content. Synthesized glasses ceramic containing BaTi4O9, Ba3TiV4O15 nanoparticles of the order of 25-35 nm and 30-46 nm, respectively were estimated using XRD. The dielectric properties over wide ranges of frequencies and temperatures were investigated as a function of BaTiO3 content by impedance spectroscopy measurements. The hopping frequency, ωh, dielectric constant, ɛ', activation energies for the DC conduction, Eσ, the relaxation process, Ec, and stretched exponential parameter β of the glasses samples have been estimated. The, ωh,β, decrease from 51.63 to 0.31 × 106 (s-1), 0.84 to 0.79 with increasing BaTiO3 respectively. Otherwise, the Eσ, increase from 0.279 to 0.306 eV with increasing BaTiO3. The value of dielectric constant equal 9.5·103 for the 2.5BaTiO3/77.5V2O5/20Bi2O3 glasses-ceramic at 330 K for 1 KHz which is ten times larger than that of same glasses composition. Finally the relaxation properties of the investigated glasses are presented in the electric modulus formalism, where the relaxation time and the respective activation energy were determined.

A preliminary research on the mechanical properties of TiAl + Ti{sub 5}Si{sub 3} dual phase alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, L.; Qiu, G.; Wu, J.

A sufficient Si addition to TiAl matrix has led to TiAl + Ti{sub 5}Si{sub 3} dual phase alloys, showing coupled-growth microstructure. Compression tests at R.T. as well as high temp indicated that the yield stress increased with increasing Ti{sub 5}Si{sub 3} volume fraction, and decreased at higher temperature. The reinforcement from Ti{sub 5}Si{sub 3} phase was obvious while high Si and Al contents resulted in low ductility. The fracture surfaces were quasi-cleavage. Further research should concern with the adjustment of the shape and amount of the second phase.

Electrorheological effect of Ti-bearing blast furnace slag with different TiC contents at 1500°C

NASA Astrophysics Data System (ADS)

Yue, Hong-rui; Jiang, Tao; Zhang, Qiao-yi; Duan, Pei-ning; Xue, Xiang-xin

2017-07-01

The electrorheological properties of CaO-SiO2-Al2O3-MgO-TiO2-TiC slags were investigated to enhance understanding of the effect of TiC addition on the viscosity, yield stress, and fluid pattern of Ti-bearing slags in a direct-current electric field. The viscosities and shear stresses of 4wt% and 8wt% TiC slags were found to increase substantially with increasing electric field intensity, whereas virtually no rheological changes were observed in the 0wt% TiC slag. The Herschel-Bulkley model was applied to demonstrate that the fluid pattern of the 4wt% TiC slag was converted from that of a Newtonian fluid to that of a Bingham fluid in response to the applied electric field; and the static yield stress increased linearly with the square of the electric field intensity.

The corrosivity and passivity of sputtered Mg-Ti alloys

DOE PAGES

Song, Guang -Ling; Unocic, Kinga A.; Meyer, III, Harry M.; ...

2015-11-30

Our study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. Moreover, the surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide filmmore » was formed on a sputtered Ti–Mg based alloy.« less

Effects of Ag doping on the photocatalytic disinfection of E. coli in bioaerosol by Ag-TiO₂/GF under visible light.

PubMed

Pham, Thanh-Dong; Lee, Byeong-Kyu

2014-08-15

Ag doped TiO2/glass fibers (Ag-TiO2/GF) were prepared and used for photocatalytic disinfection of Escherichia coli (E. coli) in an indoor air environment. The prepared photocatalysts were characterized using scanning electron microscope (SEM) for morphology, X-ray diffraction (XRD) for microstructure, UV-Visible diffuse reflectance spectra (DRS) for optical properties and X-ray photoelectron spectroscopy (XPS) to determine elemental state. The optimized weight fraction of TiO2 in the TiO2/glass fiber (TiO2/GF) was 3%. The silver content in Ag/TiO2 was altered from 1% to 10% to investigate the optimal ratio of Ag doped on the TiO2/GF for the photocatalytic disinfection of E. coli. Doped Ag enhanced the electron-hole separation as well as charge transfer efficiency between the valance band and the conduction band of TiO2. The generated electron-hole pairs reacted with water and molecular oxygen to form strong oxidative radicals, which participated in the oxidation of organic components of E. coli, resulting in bacterial death. The photocatalytic disinfection activity under visible light increased with the increase in silver content up to 7.5% and then decreased slightly with further increasing Ag content. Among the three humidity conditions used in this study (40±5%, 60±5%, 80±5%), the highest disinfection ratio of E. coli by the photocatalytic system was observed in the intermediate humidity level followed by the high humidity level. Using the 7.5% Ag-TiO2/GF and the intermediate level of humidity (60±5%), the highest disinfection ratio and disinfection capacity of E. coli were 93.53% and 26 (CFU/s cm(2)), respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

New ramsdellites LiTi 2-yV yO 4 (0≤ y≤1): Synthesis, structure, magnetic properties and electrochemical performances as electrode materials for lithium batteries

NASA Astrophysics Data System (ADS)

Kuhn, Alois; Martín, María; García-Alvarado, Flaviano

2010-01-01

The new ramsdellite series LiTi 2-yV yO 4 (0≤ y≤1) has been prepared by conventional solid state chemistry techniques and was characterized by X-ray powder diffraction and electron diffraction. To our knowledge, this is the first report on ramsdellites containing vanadium. The magnetic behaviour of these ramsdellites is strongly influenced by its vanadium content. In this sense, LiTi 2O 4 ( y=0) exhibits metallic-like temperature independent paramagnetism, but d electrons tend to localize with increasing V content. LiTiVO 4, though also paramagnetic, follows then the Curie-Weiss law. The crossover from delocalized to localized electrons is observed between compositions y=0.6 and 0.8. For y≥0.8 the magnetic results evidence an isovalent substitution mechanism of trivalent Ti by V. The electrochemical lithium intercalation and deintercalation chemistry of LiTi 2-yV yO 4 is grouped into two different operating voltage regions. Reversible lithium deintercalation of vanadium-substituted ramsdellite titanates LiTi 2-yV yO 4 in the high voltage range 2-3 V vs. Li occurs in two main steps, one at about 2 V and the other at about 3 V. The 3 V process capacity increases with the vanadium content, while the 2 V capacity decreases at the same time. The vanadium to titanium substitution rate in LiTi 2O 4 was found to be beneficial to the specific energy in as much as a 50% increase (1 V) of the working voltage is observed. On the other hand, reversible lithium intercalation in vanadium-substituted ramsdellite titanates LiTi 2-yV yO 4 in the low voltage range 1-2 V vs. Li occurs in one main single step, in which the capacity is not affected by the vanadium content, although vanadium-doping produces an improved capacity retention with an excellent cycling behaviour observed for y≤0.6.

Optical and structural properties of Mo-doped NiTiO3 materials synthesized via modified Pechini methods

NASA Astrophysics Data System (ADS)

Pham, Thanh-Truc; Kang, Sung Gu; Shin, Eun Woo

2017-07-01

In this study, molybdenum (Mo)-doped nickel titanate (NiTiO3) materials were successfully synthesized as a function of Mo content through a modified Pechini method followed by a solvothermal treatment process. Various characterization methods were employed to investigate the optical and structural properties of the materials. XRD patterns clearly showed that the NiTiO3 structure maintained a single phase with no observed crystalline structure transformations, even after the addition of 10 wt.% Mo. In the Raman spectra and XRD patterns, peak positions shifted with a change in Mo content, confirming that the NiTiO3 lattice was doped with Mo. On the other hand, Mo doping of NiTiO3 materials changed their optical properties. DRS-UV demonstrated that the addition of Mo increased photon absorption within the UV region. Relaxation processes were inhibited by Mo doping, which was evident in the PL spectra. Structural properties of the prepared materials were studied via FE-SEM and HR-TEM. The measured surface area increased proportionally with Mo content due to a reduction in grain size of the materials.

Effect of Ti content on the microstructure and mechanical behavior of (Fe 36Ni 18Mn 33Al 13) 100–xTi x high entropy alloys

DOE PAGES

Wang, Zhangwei; Wu, Margaret; Cai, Zhonghou; ...

2016-06-13

The microstructure and mechanical properties studies of a series of two-phase f.c.c./B2 (ordered b.c.c.) lamellar-structured, high entropy alloys (HEA) Fe 36Ni 18Mn 33Al 13Ti x with x up to 6 at. % Ti have been investigated. X-ray microanalysis in a TEM showed that the Ti resided mostly in the B2 phase. The lamellar spacing decreased significantly with increasing Ti content from 1.56 μm for the undoped alloy to 155 nm with an addition of 4 at. % Ti, leading to a sharp increase in room-temperature yield strength,σ y, from 270 MPa to 953 MPa, but with a concomitant decrease inmore » ductility from 22% elongation to 2.3%. Annealing at 1173 K for 20 h greatly increased the lamellar spacing of Fe 36Ni 18Mn 33Al 13Ti 4 to 577 nm, producing a corresponding decrease in σy to 511 MPa. The yield strengths of all the doped alloys decreased significantly when tensile tested at 973 K with a concomitant increase in ductility due to softening of the B2 phase. The fracture mode changed from cleavage at room temperature to a ductile dimple-type rupture at 973 K. Lastly, the results are discussed in terms of the Hall-Petch-type relationship.« less

Effect of Ti content on the microstructure and mechanical behavior of (Fe 36Ni 18Mn 33Al 13) 100–xTi x high entropy alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhangwei; Wu, Margaret; Cai, Zhonghou

The microstructure and mechanical properties studies of a series of two-phase f.c.c./B2 (ordered b.c.c.) lamellar-structured, high entropy alloys (HEA) Fe 36Ni 18Mn 33Al 13Ti x with x up to 6 at. % Ti have been investigated. X-ray microanalysis in a TEM showed that the Ti resided mostly in the B2 phase. The lamellar spacing decreased significantly with increasing Ti content from 1.56 μm for the undoped alloy to 155 nm with an addition of 4 at. % Ti, leading to a sharp increase in room-temperature yield strength,σ y, from 270 MPa to 953 MPa, but with a concomitant decrease inmore » ductility from 22% elongation to 2.3%. Annealing at 1173 K for 20 h greatly increased the lamellar spacing of Fe 36Ni 18Mn 33Al 13Ti 4 to 577 nm, producing a corresponding decrease in σy to 511 MPa. The yield strengths of all the doped alloys decreased significantly when tensile tested at 973 K with a concomitant increase in ductility due to softening of the B2 phase. The fracture mode changed from cleavage at room temperature to a ductile dimple-type rupture at 973 K. Lastly, the results are discussed in terms of the Hall-Petch-type relationship.« less

Effect of food processing organic matter on photocatalytic bactericidal activity of titanium dioxide (TiO2).

PubMed

Yemmireddy, Veerachandra K; Hung, Yen-Con

2015-07-02

The purpose of this study was to determine the effect of food processing organic matter on photocatalytic bactericidal activity of titanium dioxide (TiO2) nanoparticles (NPs). Produce and meat processing wash solutions were prepared using romaine lettuce and ground beef samples. Physico-chemical properties such as pH, turbidity, chemical oxygen demand (COD), total phenolics (for produce) and protein (for meat) content of the extracts were determined using standard procedures. The photocatalytic bactericidal activity of TiO2 (1 mg/mL) in suspension with or without organic matter against Escherichia coli O157:H7 (5-strain) was determined over a period of 3h. Increasing the concentration of organic matter (either produce or meat) from 0% to 100% resulted in 85% decrease in TiO2 microbicidal efficacy. 'Turbidity, total phenolics, and protein contents in wash solutions had significant effect on the log reduction. Increasing the total phenolics content in produce washes from 20 to 114 mg/L decreased the log reduction from 2.7 to 0.38 CFU/mL, whereas increasing the protein content in meat washes from 0.12 to 1.61 mg/L decreased the log reduction from and 5.74 to 0.87 CFU/mL. Also, a linear correlation was observed between COD and total phenolics as well as COD and protein contents. While classical disinfection kinetic models failed to predict, an empirical equation in the form of "Y=me(nX)" (where Y is log reduction, X is COD, and m and n are reaction rate constants) predicted the disinfection kinetics of TiO2 in the presence of organic matter (R(2)=94.4). This study successfully identified an empirical model with COD as a predictor variable to predict the bactericidal efficacy of TiO2 when used in food processing environment. Copyright © 2015 Elsevier B.V. All rights reserved.

CdTe Nanocrystal Hetero-Junction Solar Cells with High Open Circuit Voltage Based on Sb-doped TiO₂ Electron Acceptor Materials.

PubMed

Li, Miaozi; Liu, Xinyan; Wen, Shiya; Liu, Songwei; Heng, Jingxuan; Qin, Donghuan; Hou, Lintao; Wu, Hongbin; Xu, Wei; Huang, Wenbo

2017-05-03

We propose Sb-doped TiO₂ as electron acceptor material for depleted CdTe nanocrystal (NC) hetero-junction solar cells. Novel devices with the architecture of FTO/ZnO/Sb:TiO₂/CdTe/Au based on CdTe NC and TiO₂ precursor are fabricated by rational ambient solution process. By introducing TiO₂ with dopant concentration, we are able to tailor the optoelectronic properties of NC solar cells. Our novel devices demonstrate a very high open circuit voltage of 0.74 V, which is the highest V oc reported for any CdTe NC based solar cells. The power conversion efficiency (PCE) of solar cells increases with the increase of Sb-doped content from 1% to 3%, then decreases almost linearly with further increase of Sb content due to the recombination effect. The champion device shows J sc , V oc , FF, and PCE of 14.65 mA/cm², 0.70 V, 34.44, and 3.53% respectively, which is prospective for solution processed NC solar cells with high V oc .

CdTe Nanocrystal Hetero-Junction Solar Cells with High Open Circuit Voltage Based on Sb-doped TiO2 Electron Acceptor Materials

PubMed Central

Li, Miaozi; Liu, Xinyan; Wen, Shiya; Liu, Songwei; Heng, Jingxuan; Qin, Donghuan; Hou, Lintao; Wu, Hongbin; Xu, Wei; Huang, Wenbo

2017-01-01

We propose Sb-doped TiO2 as electron acceptor material for depleted CdTe nanocrystal (NC) hetero-junction solar cells. Novel devices with the architecture of FTO/ZnO/Sb:TiO2/CdTe/Au based on CdTe NC and TiO2 precursor are fabricated by rational ambient solution process. By introducing TiO2 with dopant concentration, we are able to tailor the optoelectronic properties of NC solar cells. Our novel devices demonstrate a very high open circuit voltage of 0.74 V, which is the highest Voc reported for any CdTe NC based solar cells. The power conversion efficiency (PCE) of solar cells increases with the increase of Sb-doped content from 1% to 3%, then decreases almost linearly with further increase of Sb content due to the recombination effect. The champion device shows Jsc, Voc, FF, and PCE of 14.65 mA/cm2, 0.70 V, 34.44, and 3.53% respectively, which is prospective for solution processed NC solar cells with high Voc. PMID:28467347

Fe doped TiO2 nanofibers on the surface of graphene sheets for photovoltaics applications

NASA Astrophysics Data System (ADS)

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Charpentier, Paul A.

2011-08-01

Highly ordered, visible light driven TiO2 nanowire arrays doped with Fe photocatalysts were grown on the surface of functionalized graphene sheets (FGSs) using a sol-gel method with titanium isopropoxide (TIP) monomer, acetic acid (HAc) as the polycondensation agent and iron chloride in the green solvent, supercritical carbon dioxide (scCO2). The morphology of the synthesized materials was studied by SEM and TEM, which showed uniform formation of Fe doped TiO2 nanofibers on the surface of graphene sheets, which acted as a template for nanowire growth through surface -COOH functionalities. Increasing Fe content in the nanowires did not change the morphology significantly. Optical properties of the synthesized composites were examined by UV spectroscopy which showed a significant reduction in band gap with increasing Fe content, i.e. 2.25 eV at 0.6% Fe. The enhancement of the optical properties of synthesized materials was confirmed by photocurrent measurement. The optimum sample containing 0.6% Fe doped TiO2 on the graphene sheets increased the power conversation efficiency by 6-fold in comparison to TiO2 alone.

Effect of Al content on structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yurchenko, N.Yu.

2016-11-15

In present study, structure and mechanical properties of the Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) high-entropy alloys after arc melting and annealing at 1200 °C for 24 h are investigated. The CrNbTiVZr alloy is composed of body centered cubic (bcc) and C15 (face centered cubic) Laves phases while the Al{sub x}CrNbTiVZr (x = 0.25; 0.5; 1) alloys consist of bcc and two C14 (hexagonal close packed) Laves phases with different chemical compositions. Thermodynamic modeling predicts existence of two phases – bcc and C15 Laves phase and broadening of single bcc phase field due to Al addition. The densitymore » of the alloys decreases with the increase of Al content. The alloys are found to be extremely brittle at room temperature and 600 °C. The alloys have high strength at temperatures of 800–1000 °C. For example, yield strength at 800 °C increases from 440 MPa for the CrNbTiVZr alloy to 1250 MPa for the AlCrNbTiVZr alloy. The experimental phase composition of the Al{sub x}CrNbTiVZr alloys is compared with predicted equilibrium phases and the factors governing the transformation of C15 to C14 Laves phases due to Al addition to the CrNbTiVZr alloy analyzed. Specific properties of the alloys are compared with other high-entropy alloys and commercial Ni-based superalloys. - Highlights: •Al{sub x}CrNbTiVZr (x = 0; 0.25; 0.5; 1) alloys are arc melted and annealed at 1200 °C. •The CrNbTiVZr alloy has bcc and C15 Laves phases. •The Al-containing alloys are composed of bcc and two C14 Laves phases. •The alloys demonstrate high specific strength at temperatures of 800 °C and 1000 °C. •The strength of the alloys increases in proportion with increase of Al content.« less

Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

NASA Astrophysics Data System (ADS)

Lee, Dongmyoung; Sun, Juhyun; Kang, Donghan; Shin, Seungyoung; Hong, Juhwa

2014-12-01

Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti x Cu y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

p-Aminophenylacetic acid-mediated synthesis of monodispersed titanium oxide hybrid microspheres in ethanol solution.

PubMed

Zhang, Hongye; Xie, Yun; Liu, Zhimin; Tao, Ranting; Sun, Zhenyu; Ding, Kunlun; An, Guimin

2009-10-15

Monodispersed TiO2 hybrid microspheres were prepared via the hydrolysis of titanium isopropoxide (TTIP) in ethanol solution containing p-aminophenylacetic acid (APA). The effects of the APA:TTIP molar ratio, water content, reaction time and reaction temperature on the morphology of the resultant spheres were investigated. The products were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. It was demonstrated that the diameters of the resultant TiO2 spheres could be tuned in the range of 380-800 nm by changing the APA:TTIP molar ratio (1:3 to 3:1) and water content (1-3 v/v%) in the reaction medium, and that increasing the APA:TTIP molar ratio led to larger TiO2 hybrid spheres while increasing the water content decreased their size. The loading content of APA in the hybrid spheres could reach 20 wt.% as they were prepared with the APA:TTIP ratio of 3:1. The possible formation mechanism of the hybrid spheres was also investigated. It was found that APA slowed down the hydrolysis rate of the titanium precursor so that resulted in the formation of the TiO2 spheres. In addition, the APA present in TiO2 spheres acted as a reducing agent to in situ convert HAuCl4 into metallic Au on the surface of the TiO2 spheres. The catalytic activity of the resultant Au/APA-TiO2 composite was examined using transfer hydrogenation of phenylacetone with 2-propanol, and it was indicated that the catalyst displayed high efficiency for this reaction.

Microstructure evolution and mechanical properties of TiCN-Cr nano/micro composite coatings prepared by reactive plasma spraying

NASA Astrophysics Data System (ADS)

Zhang, Fanyong; He, Jining; Chen, Kai; Qin, Yanfang; Li, Chao; Yin, Fuxing

2018-01-01

Nanostructured TiCN based composite coatings with various Cr content were prepared by reactive plasma spray (RPS) from mixed powder (Ti-graphite + Cr) under nitrogen atmosphere. Results showed that composite coatings consisted mainly of TiC0.7N0.3 phase and residual metal Cr. Metal Cr plates were homogeneously embedded in TiCN matrix with good interface bond. The TiCN-Cr composite coatings exhibited lower porosity than TiCN coatings, but increasing porosity with excess Cr addition (30 wt.%). The TiCN-20 wt.% Cr coating showed the highest hardness (1309 HV0.2) among composite coatings, slight lower than the TiCN matrix coating (1526 HV0.2). Compared with the TiCN matrix coating, the TiCN-Cr composite coatings showed higher variability in surface microhardness distribution. The TiCN-Cr composite coatings showed slight higher friction coefficients (0.4-0.6) than TiCN matrix coating (0.35). The wear resistance of TiCN-Cr composite coatings was improved with less mass loss compared with TiCN coating under the test load of 400 N. The TiCN-Cr composite coatings with high Cr content showed the mixture of abrasive and adhesive wear.

Nanostructured titanium-silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

NASA Astrophysics Data System (ADS)

Bai, Long; Hang, Ruiqiang; Gao, Ang; Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin; Zhao, Lingzhou; Chu, Paul K.

2015-11-01

Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium-silver (Ti-Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti-Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti-Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti-Ag coatings.

Promotion of redox and stability features of doped Ce-W-Ti for NH3-SCR reaction over a wide temperature range

NASA Astrophysics Data System (ADS)

Zhao, Kun; Han, Weiliang; Lu, Gongxuan; Lu, Jiangyin; Tang, Zhicheng; Zhen, Xinping

2016-08-01

In this study, transition metals Co, Mn, and Cu were introduced into a Ce-W-Ti catalyst to promote low-temperature catalytic activity. Among these metal-modified M/Ce-W-Ti catalysts (M represents Co, Mn, or Cu), the Cu/Ce-W-Ti catalyst with an optimized Cu content of 5 wt.% exhibited more than 90% conversion of nitrogen oxide (NOx) in the selective catalytic reduction by NH3 over a wide temperature range (260-400 °C). This catalyst likewise exhibited higher resistance to SO2 gas and water vapor under severe test conditions. On the basis of the characterization results by powder X-ray diffraction and X-ray photoelectron spectroscopy, we concluded that the superior catalytic properties of the Cu/Ce-W-Ti catalyst could be attributed to the highly dispersed Cu species, which increased the contents of Ce3+ species and adsorbed oxygen species in the catalysts. In addition, the NH3 temperature-programmed desorption results demonstrated that the Cu species doped into the Ce-W-Ti catalysts optimized surface acid content.

Experimental Study on Reaction Characteristics of PTFE/Ti/W Energetic Materials under Explosive Loading

PubMed Central

Li, Yan; Jiang, Chunlan; Wang, Zaicheng; Luo, Puguang

2016-01-01

Metal/fluoropolymer composites represent a new category of energetic structural materials that release energy through exothermic chemical reactions initiated under shock loading conditions. This paper describes an experiment designed to study the reaction characteristics of energetic materials with low porosity under explosive loading. Three PTFE (polytetrafluoroethylene)/Ti/W mixtures with different W contents are processed through pressing and sintering. An inert PTFE/W mixture without reactive Ti particles is also prepared to serve as a reference. Shock-induced chemical reactions are recorded by high-speed video through a narrow observation window. Related shock parameters are calculated based on experimental data, and differences in energy release are discussed. The results show that the reaction propagation of PTFE/Ti/W energetic materials with low porosity under explosive loading is not self-sustained. As propagation distance increases, the energy release gradually decreases. In addition, reaction failure distance in PTFE/Ti/W composites is inversely proportional to the W content. Porosity increased the failure distance due to higher shock temperature. PMID:28774056

Oxygen-vacancy-mediated dielectric property in perovskite Eu0.5Ba0.5TiO3-δ epitaxial thin films

NASA Astrophysics Data System (ADS)

Li, Weiwei; Gu, Junxing; He, Qian; Zhang, Kelvin H. L.; Wang, Chunchang; Jin, Kuijuan; Wang, Yongqiang; Acosta, Matias; Wang, Haiyan; Borisevich, Albina Y.; MacManus-Driscoll, Judith L.; Yang, Hao

2018-04-01

Dielectric relaxation in ABO3 perovskite oxides can result from many different charge carrier-related phenomena. Despite a strong understanding of dielectric relaxations, a detailed investigation of the relationship between the content of oxygen vacancies (VO) and dielectric relaxation has not been performed in perovskite oxide films. In this work, we report a systematic investigation of the influence of the VO concentration on the dielectric relaxation of Eu0.5Ba0.5TiO3-δ epitaxial thin films. Nuclear resonance backscattering spectrometry was used to directly measure the oxygen concentration in Eu0.5Ba0.5TiO3-δ films. We found that dipolar defects created by VO interact with the off-centered Ti ions, which results in the dielectric relaxation in Eu0.5Ba0.5TiO3-δ films. Activation energy gradually increases with the increasing content of VO. The present work significantly extends our understanding of relaxation properties in oxide films.

Viscosity of TiO2-FeO-Ti2O3-SiO2-MgO-CaO-Al2O3 for High-Titania Slag Smelting Process

NASA Astrophysics Data System (ADS)

Hu, Kai; Lv, Xuewei; Li, Shengping; Lv, Wei; Song, Bing; Han, Kexi

2018-05-01

The present study demonstrates the dependence of viscosity on chemical composition and temperature of high-titania slag, a very important raw material for producing titanium dioxide. The results indicated that completely molten high-titania slag exhibits a viscosity of less than 1 dPa s with negligible dependence on temperature. However, it increases dramatically with decreasing temperature slightly below the critical temperature, i.e., the solidus temperature of the slag. Above the critical temperature, the slag samples displayed the same order of viscosity at 0.6 dPa s, regardless of their compositional variation. However, the FeO, CaO, and MgO were confirmed to decrease viscosity, while SiO2 and Ti2O3 increase it. The apparent activation energy for viscosity-temperature relation and liquidus temperature based on experiments and thermodynamic calculations are also presented. Conclusively, the critical temperatures of the slags are on average 15 K below their corresponding calculated liquidus temperatures. The increase in FeO content was found to considerably lower the critical temperature, while the increase in both Ti2O3 and TiO2 contents increases it. The main phases of the slag in solid state, as indicated by X-ray diffraction, are (Fe, Mg) x Ti y O5 (x + y = 3, pseudobrookite) and rutile.

Room temperature deposition of sputtered TiN films for superconducting coplanar waveguide resonators

NASA Astrophysics Data System (ADS)

Ohya, S.; Chiaro, B.; Megrant, A.; Neill, C.; Barends, R.; Chen, Y.; Kelly, J.; Low, D.; Mutus, J.; O'Malley, P. J. J.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Yin, Y.; Schultz, B. D.; Palmstrøm, C. J.; Mazin, B. A.; Cleland, A. N.; Martinis, John M.

2014-01-01

We present a systematic study of the properties of room temperature deposited TiN films by varying the deposition conditions in an ultra-high-vacuum reactive magnetron sputtering chamber. By increasing the deposition pressure from 2 to 9 mTorr while keeping a nearly stoichiometric composition of Ti1-xNx (x = 0.5) without substrate heating, the film resistivity increases, the dominant crystal orientation changes from (100) to (111), grain boundaries become clearer, and the strong compressive in-plane strain changes to weak tensile in-plane strain. The TiN films absorb a high concentration of contaminants including hydrogen, carbon, and oxygen when they are exposed to air after deposition. With the target-substrate distance set to 88 mm the contaminant levels increase from ˜0.1% to ˜10% as the pressure is increased from 2 to 9 mTorr. The contaminant concentrations also correlate with in-plane distance from the center of the substrate and increase by roughly two orders of magnitude as the target-substrate distance is increased from 88 to 266 mm. These contaminants are found to strongly influence the properties of TiN thin films. For instance, the resistivity of stoichiometric films increases by around a factor of 5 as the oxygen content increases from 0.1% to 11%. These results strongly suggest that the energy of the sputtered TiN particles plays a crucial role in determining the TiN film properties, and that it is important to precisely control the energy of these particles to obtain high-quality TiN films. Superconducting coplanar waveguide resonators made from a series of nearly stoichiometric films grown at pressures from 2 to 7 mTorr show a substantial increase in intrinsic quality factor from ˜104 to ˜106 as the magnitude of the compressive strain decreases from nearly 3800 MPa to approximately 150 MPa and the oxygen content increases from 0.1% to 8%. Surprisingly, the films with a higher oxygen content exhibit lower loss, but care must be taken when depositing at room temperature to avoid nonuniform oxygen incorporation, which presents as a radially dependent resistivity and becomes a radially dependent surface inductance in the superconductor.

Tribo-Mechanical Properties of HVOF Deposited Fe3Al Coatings Reinforced with TiB2 Particles for Wear-Resistant Applications

PubMed Central

Amiriyan, Mahdi; Blais, Carl; Savoie, Sylvio; Schulz, Robert; Gariépy, Mario; Alamdari, Houshang

2016-01-01

This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. PMID:28787917

Inclusion Characteristics and Acicular Ferrite Nucleation in Ti-Containing Weld Metals of X80 Pipeline Steel

NASA Astrophysics Data System (ADS)

Wang, Bingxin; Liu, Xianghua; Wang, Guodong

2018-06-01

X80 steel weld metals with Ti contents of 0.003 to 0.13 pct were prepared by the single-pass submerged-arc welding process. The effects of Ti content in weld metals on the constituent phases of inclusions and chemical compositions of the constituent phases, as well as the potency of acicular ferrite (AF) nucleation on the inclusions were investigated. Moreover, the crystallographic orientation relationship between the AF and inclusion was examined. The results show that with an increase in Ti content, the primary constituent phases of the inclusions change from the (Mn-Al-Si-O) compound to a mixture of spinel and pseudobrookite solid solutions, and eventually to pseudobrookite. The spinel solid solution is characterized by the MnTi2O4 constituent. Compared to pseudobrookite, spinel has a lower Ti concentration, but a significantly higher Mn content. In the case of the presence of a considerable amount of spinel, the Mn element is enriched strongly in the inclusions, resulting in the development of a Mn-depleted zone (MDZ) in the matrix around the inclusions, which enhances the driving force for AF formation. AF shows the Baker-Nutting orientation relationship with MnTi2O4. The formation of MDZ and the presence of the Baker-Nutting orientation relationship promote the ability of inclusions to nucleate the intragranular AF.

Inclusion Characteristics and Acicular Ferrite Nucleation in Ti-Containing Weld Metals of X80 Pipeline Steel

NASA Astrophysics Data System (ADS)

Wang, Bingxin; Liu, Xianghua; Wang, Guodong

2018-03-01

X80 steel weld metals with Ti contents of 0.003 to 0.13 pct were prepared by the single-pass submerged-arc welding process. The effects of Ti content in weld metals on the constituent phases of inclusions and chemical compositions of the constituent phases, as well as the potency of acicular ferrite (AF) nucleation on the inclusions were investigated. Moreover, the crystallographic orientation relationship between the AF and inclusion was examined. The results show that with an increase in Ti content, the primary constituent phases of the inclusions change from the (Mn-Al-Si-O) compound to a mixture of spinel and pseudobrookite solid solutions, and eventually to pseudobrookite. The spinel solid solution is characterized by the MnTi2O4 constituent. Compared to pseudobrookite, spinel has a lower Ti concentration, but a significantly higher Mn content. In the case of the presence of a considerable amount of spinel, the Mn element is enriched strongly in the inclusions, resulting in the development of a Mn-depleted zone (MDZ) in the matrix around the inclusions, which enhances the driving force for AF formation. AF shows the Baker-Nutting orientation relationship with MnTi2O4. The formation of MDZ and the presence of the Baker-Nutting orientation relationship promote the ability of inclusions to nucleate the intragranular AF.

Two-phase nc-TiN/a-(C,CN{sub x}) nanocomposite films: A HRTEM and MC simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, J.; Lu, Y. H.; Hu, X. J.

2013-06-18

The grain growth in two-phase nanocomposite Ti-C{sub x}-N{sub y} thin films grown by reactive close-field unbalanced magnetron sputtering in an Ar-N{sub 2} gas mixture with microstructures comprising of nanocrystalline (nc-) Ti(N,C) phase surrounded by amorphous (a-) (C,CN{sub x}) phase was investigated by a combination of high-resolution transmission electron microscopy (HRTEM) and Monte Carlo (MC) simulations. The HRTEM results revealed that amorphous-free solid solution Ti(C,N) thin films exhibited polycrystallites with different sizes, orientations and irregular shapes. The grain size varied in the range between several nanometers and several decade nanometers. Further increase of C content (up to {approx}19 at.% C) mademore » the amorphous phase wet nanocrystallites, which strongly hindered the growth of nanocrystallites. As a result, more regular Ti(C,N) nanocrystallites with an average size of {approx}5 nm were found to be separated by {approx}0.5-nm amorphous phases. When C content was further increased (up to {approx}48 at.% in this study), thicker amorphous matrices were produced and followed by the formation of smaller sized grains with lognormal distribution. Our MC analysis indicated that with increasing amorphous volume fraction (i.e. increasing C content), the transformation from nc/nc grain boundary (GB)-curvature-driven growth to a/nc GB-curvature-driven growth is directly responsible for the observed grain growth from great inhomogeneity to homogeneity process.« less

Density functional theory computational study of ferroelectricity and piezoelectricity in BaTiO3/PbTiO3 (0 1 1) superlattices

NASA Astrophysics Data System (ADS)

Lou, Yaoding; Deng, Junkai; Zhe Liu, Jefferson

2018-04-01

The structure, ferroelectricity (FE), and piezoelectricity of epitaxial BaTiO3/PbTiO3 (BTO/PTO) (0 1 1) superlattices are studied using density functional theory calculations. Our results show that compressive strain arising from the SrTiO3 (0 1 1) substrate stabilizes the (BTO) m /(PTO) n (0 1 1) superlattices in orthorhombic phase with the FE polarization along [0 1 1] direction. Tuning the BTO contents significantly changes the structural, ferroelectric and piezoelectric properties. The FE polarization of superlattices significantly drops with increasing BTO contents, which can be attributed to depolarization of the PTO layers. The averaged c/a ratio of the whole superlattices exhibits anomalous non-monotonic relation with respect to BTO contents. Interestingly, our results predict the (0 1 1) superlattices can enhance the piezoelectric coefficient e 33 with a maximum value at ~67% BTO concentration. This result suggests a potential avenue to design high performance piezoelectric materials with less Pb contents. In-depth analysis reveals the B-site Ti cation as the origin for the enhanced e 33 value, which implies the potential of B-site cation engineering in perovskite heterostructure designs.

Water sensitivity of the seismic properties of polycrystalline olivine

NASA Astrophysics Data System (ADS)

Cline, C. J., II; Jackson, I.; Faul, U.; Berry, A.

2016-12-01

Fully synthetic solgel-derived Fo90 olivine specimens have been fabricated with varying concentrations of hydroxyl, chemically bound as doubly protonated Si vacancies associated with nearby Ti/Mg substitution (the `Ti-clinohumite' defect). The `water' contents of three such specimens hot-pressed within welded Pt capsules are controlled by the amount of added TiO2-dopant and ranged between 176 and 802 ppm Ti/Si, providing concentrations of bound hydrogen ranging between 330 and 1150 ppm H/Si respectively. These sol-gel derived specimens, along with another natural Ti-bearing specimen hot-pressed from powder produced by grinding hand-picked single crystals of San Carlos olivine, were then each subsequently wrapped in Pt and interrogated under water-undersaturated conditions via forced torsional oscillation. Testing was conducted at seismic periods of 1 - 1000 s and 200 MPa confining pressure during slow staged cooling from 1200 to 25 °C. All Ti-doped hydrous specimens tested, including the San Carlos olivine specimen, show high temperature background behavior, involving monotonically increasing levels of dissipation and decreasing values of shear modulus with increasing oscillation period and increasing temperature. Comparison of the mechanical behavior observed in these water-undersaturated specimens to that for a similarly fabricated dry Ti-bearing olivine specimen shows a striking contrast, with much more dissipation and lower modulus observed in the hydrous specimens, but with limited sensitivity of seismic properties to the total water content among the hydrous specimens in the series. Further experiments in progress on Pt-sleeved, dry, undoped Fo90 are designed to clarify further the sensitivity of the seismic properties to water content and possibly oxygen fugacity.

High-temperature wear and oxidation behaviors of TiNi/Ti2Ni matrix composite coatings with TaC addition prepared on Ti6Al4V by laser cladding

NASA Astrophysics Data System (ADS)

Lv, Y. H.; Li, J.; Tao, Y. F.; Hu, L. F.

2017-04-01

TiNi/Ti2Ni matrix composite coatings were produced on Ti6Al4V surfaces by laser cladding the mixed powders of Ni-based alloy and different contents of TaC (0, 5, 10, 15, 20, 30 and 40 wt.%). Microstructures of the coatings were investigated. High-temperature wear tests of the substrate and the coatings were carried out at 600 °C in air for 30 min. High-temperature oxidation tests of the substrate and the coatings were performed at 1000 °C in air for 50 h. Wear and oxidation mechanisms were revealed in detail. The results showed that TiNi/Ti2Ni as the matrix and TiC/TiB2/TiB as the reinforcements are the main phases of the coatings. The friction coefficients of the substrate and the coatings with different contents of TaC were 0.431 (the substrate), 0.554 (0 wt.%), 0.486 (5 wt.%), 0.457 (10 wt.%), 0.458 (15 wt.%), 0.507 (20 wt.%), 0.462 (30 wt.%) and 0.488 (40 wt.%). The wear rates of the coatings were decreased by almost 83%-98% than that of the substrate and presented a decreasing tendency with increasing TaC content. The wear mechanism of the substrate was a combination of serious oxidation, micro-cutting and brittle debonding. For the coatings, oxidation and slight scratching were predominant during wear, accompanied by slight brittle debonding in partial zones. With the increase in content of TaC, the oxidation film better shielded the coatings from destruction due to the effective friction-reducing role of Ta2O5. The oxidation rates of the substrate and the coatings with different contents of TaC at 1000 °C were 12.170 (the substrate), 5.886 (0 wt.%), 4.937 (5 wt.%), 4.517 (10 wt.%), 4.394 (15 wt.%), 3.951 (20 wt.%), 4.239 (30 wt.%) and 3.530 (40 wt.%) mg2 cm-4 h-1, respectively. The oxidation film formed outside the coating without adding TaC was composed of TiO2, NiO, Cr2O3, Al2O3 and SiO2. When TaC was added, Ta2O5 and TaC were also detected, which effectively improved the oxidation resistance of the coatings. The addition of TaC contributed to the improvement in high-temperature wear and oxidation resistance.

Trophic transfer and accumulation of TiO2 nanoparticles from clamworm (Perinereis aibuhitensis) to juvenile turbot (Scophthalmus maximus) along a marine benthic food chain.

PubMed

Wang, Zhenyu; Yin, Liyun; Zhao, Jian; Xing, Baoshan

2016-05-15

In the present work, we investigated the potential benthic trophic transfer of TiO2 nanoparticles (NPs) from clamworm (Perinereis aibuhitensis) to juvenile turbot (Scophthalmus maximus) and their related distribution and toxicity. TiO2 NPs (at 10, 50 and 100 mg/L) could be taken up by clamworms, and mainly accumulated in the lower-digestive tract. TiO2 NPs were able to transfer from clamworms to juvenile turbots. The accumulation of TiO2 NPs in juvenile turbots increased with increasing Ti contents in clamworms during the dietary exposure, however, no biomagnification (BMFs, 0.30-0.33) of TiO2 NPs was observed. For both dietary and waterborne exposure, accumulation of TiO2 NPs was higher in the gill, intestine and stomach of juvenile turbot, following by skin, liver, and muscle. During dietary exposure at Day 20, the growth of turbots was reduced, and abnormal symptoms of liver and spleen were detected. Moreover, both dietary (50 and 100 mg/L TiO2 NPs-treated clamworms) and waterborne (100 mg/L TiO2 NPs) exposures led to significantly lower protein and higher lipid contents, suggesting the nutrition quality reduction of turbots. The findings from this work highlighted the trophic transfer of TiO2 NPs in marine benthic food chain, leading to the potential negative impact on marine aquaculture and food quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

The preparation and characterization of La doped TiO 2 nanoparticles and their photocatalytic activity

NASA Astrophysics Data System (ADS)

Liqiang, Jing; Xiaojun, Sun; Baifu, Xin; Baiqi, Wang; Weimin, Cai; Honggang, Fu

2004-10-01

In this paper, pure and La doped TiO2 nanoparticles with different La content were prepared by a sol-gel process using Ti (OC4H9)4 as raw material, and also were characterized by XRD, TG-DTA, TEM, XPS, DRS and Photoluminescence (PL) spectra. We mainly investigated the effects of calcining temperature and La content on the properties and the photocatalytic activity for degrading phenol of as-prepared TiO2 samples, and also discussed the relationships between PL spectra and photocatalytic activity as well as the mechanisms of La doping on TiO2 phase transformation. The results showed that La3+ did not enter into the crystal lattices of TiO2 and was uniformly dispersed onto TiO2 as the form of La2O3 particles with small size, which possibly made La dopant have a great inhibition on TiO2 phase transformation; La dopant did not give rise to a new PL signal, but it could improve the intensity of PL spectra with a appropriate La content, which was possibly attributed to the increase in the content of surface oxygen vacancies and defects after doping La; La doped TiO2 nanoparticles calcined at 600°C exhibited higher photocatalytic activity, indicating that 600°C was an appropriate calcination temperature. The order of photocatalytic activity of La doped TiO2 samples with different La content was as following: 1>1.5>3>0.5>5>0 mol%, which was the same as the order of their PL intensity, namely, the stronger the PL intensity, the higher the photocatalytic activity, demonstrating that there were certain relationships between PL spectra and photocatalytic activity. This could be explained by the points that PL spectra mainly resulted from surface oxygen vacancies and defects during the process of PL, while surface oxygen vacancies and defects could be favorable in capturing the photoinduced electrons during the process of photocatalytic reactions.

Characterization of Ternary NiTiPd High-Temperature Shape-Memory Alloys under Load-Biased Thermal Cycling

NASA Technical Reports Server (NTRS)

Bigelow, Glen S.; Padula, Santo A.; Noebe, Ronald D.; Garg, Anita; Gaydosh, Darrell

2010-01-01

While NiTiPd alloys have been extensively studied for proposed use in high-temperature shape-memory applications, little is known about the shape-memory response of these materials under stress. Consequently, the isobaric thermal cyclic responses of five (Ni,Pd)49.5Ti50.5 alloys with constant stoichiometry and Pd contents ranging from 15 to 46 at. pct were investigated. From these tests, transformation temperatures, transformation strain (which is proportional to work output), and unrecovered strain per cycle (a measure of dimensional instability) were determined as a function of stress for each alloy. It was found that increasing the Pd content over this range resulted in a linear increase in transformation temperature, as expected. At a given stress level, work output decreased while the amount of unrecovered strain produced during each load-biased thermal cycle increased with increasing Pd content, during the initial thermal cycles. However, continued thermal cycling at constant stress resulted in a saturation of the work output and nearly eliminated further unrecovered strain under certain conditions, resulting in stable behavior amenable to many actuator applications.

Microstructures and Properties of W-Ti Alloys Prepared Under Different Cooling Conditions

NASA Astrophysics Data System (ADS)

Dai, Weili; Liang, Shuhua; Yang, Qing; Zou, Juntao; Zhuo, Longchao

2016-07-01

W-(10 to 15) wt.% Ti alloys were sintered at 1400 or 1500 °C and cooled under different cooling conditions. The microstructures and properties of W-Ti alloys were affected by the cooling conditions. XRD, SEM, EBSD, and TEM were carried out to investigate the effects of cooling conditions and sintering temperature on the microstructures of W-Ti alloys. The nanohardness and elastic modulus of the alloys were also investigated. The results showed that when the temperature was 1500 °C, the content of Ti-rich phase in W-(10 to 15) wt.% Ti alloys decreased obviously with the increase of cooling rate (the average cooling rate of furnace cooling, air cooling and water cooling was 0.2, 10, and 280 °C/s, respectively). For the W-10 wt.% Ti alloy, the content decreased from 20.5 to 9.7%, and the grain size decreased from 2.33 to 0.67 μm. When the temperature decreased to 1400 °C, the grain size was also decreased sharply with the increase of cooling rate, but there was a little change in the microstructure. Meanwhile, the grain sizes were smaller than those of the alloys sintered at 1500 °C. The nanohardness and elastic modulus increased with the increase of cooling rate, and the alloys sintered at different temperatures had different nanohardness and elastic modulus which depended on the cooling conditions. Sintering at a proper temperature and then cooling at a certain cooling condition was a useful method to fabricate alloy with less Ti-rich phase and high properties.

Scanning probe microscopy for the analysis of composite Ti/hydrocarbon plasma polymer thin films

NASA Astrophysics Data System (ADS)

Choukourov, A.; Grinevich, A.; Slavinska, D.; Biederman, H.; Saito, N.; Takai, O.

2008-03-01

Composite Ti/hydrocarbon plasma polymer films with different Ti concentration were deposited on silicon by dc magnetron sputtering of titanium in an atmosphere of argon and hexane. As measured by Kelvin force microscopy and visco-elastic atomic force microscopy, respectively, surface potential and hardness increase with increasing Ti content. Adhesion force to silicon and to fibrinogen molecules was stronger for the Ti-rich films as evaluated from the AFM force-distance curves. Fibrinogen forms a very soft layer on these composites with part of the protein molecules embedded in the outermost region of the plasma polymer. An increase of the surface charge due to fibrinogen adsorption has been observed and attributed to positively charged αC domains of fibrinogen molecule.

TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

PubMed

Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

2014-09-01

A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

Effects of crystallization on structural and dielectric properties of thin amorphous films of (1 - x)BaTiO3-xSrTiO3 (x=0-0.5, 1.0)

NASA Astrophysics Data System (ADS)

Kawano, H.; Morii, K.; Nakayama, Y.

1993-05-01

The possibilities for fabricating solid solutions of (Ba1-x,Srx)TiO3 (x≤0.5,1.0) by crystallization of amorphous films and for improving their dielectric properties by adjusting the Sr content were investigated. Thin amorphous films were prepared from powder targets consisting of mixtures of BaTiO3 and SrTiO3 by sputtering with a neutralized Ar-ion beam. The amorphous films crystallized into (Ba1-x, Srx)TiO3 solid solutions with a cubic perovskite-type structure after annealing in air at 923 K for more than 1 h. The Debye-type dielectric relaxation was observed for the amorphous films, whereas the crystallized films showed paraelectric behavior. The relative dielectric constants were of the order of 20 for the amorphous samples, but increased greatly after crystallization to about 60-200, depending on the composition; a larger increase in the dielectric constant was observed in the higher Sr content films, in the range x≤0.5, which could be correlated with an increase in the grain size of the crystallites. The crystallization processes responsible for the difference in the grain size are discussed based on the microstructural observations.

Influence of nano-TiO2 particles on the bioaccumulation of Cd in soybean plants (Glycine max): A possible mechanism for the removal of Cd from the contaminated soil.

PubMed

Singh, Jiwan; Lee, Byeong-Kyu

2016-04-01

Phytoremediation is a highly efficient technique for the elimination of trace elements from contaminated soils through the shoots and roots of plants. This study was carried out to investigate the effects of nano-titanium dioxide (TiO2) on Cd uptake by soybean plants. The objective of the present research was to examine the potential to improve the phytoextraction of Cd by the application of nano-TiO2 particles. The results showed that an addition of Cd to the soil significantly decreased plant growth and the biomass, pigment and protein contents. Increases in the proline content and malondialdehyde (MDA) indicate that Cd toxicity stresses the plants. Fourier transform infrared spectroscopy (FTIR) was used to determine variations in functional groups due to the Cd taken up into the shoot and root tissues of plants. An application of nano-TiO2 particles restricts Cd toxicity by increasing the photosynthetic rate and growth parameters of the plants. The uptake of Cd was also increased from 128.5 to 507.6 μg/plant with an increase in the nano-TiO2 concentration from 100 to 300 mg/kg in the soil. The application of nano-TiO2 significantly enhanced Cd uptake in the plants. The results of this study thus demonstrate that an application of nano-TiO2 can increase Cd uptake and minimize Cd stress in soybean plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stress corrosion behavior of Ru-enhanced alpha-beta titanium alloys in methanol solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schutz, R.W.; Horrigan, J.M.; Bednarowicz, T.A.

1998-12-31

Conservative, practical guidelines for the minimum water content required to prevent methanolic stress corrosion cracking (SCC) of Ti-6Al-4V-Ru and Ti-3Al-2.5V-Ru alloy tubulars have been developed from slow strain rate testing in plain and acidified NaCl-saturated methanol-water solutions at 25 C. A minimum methanol water content of 10 wt.% is proposed for Ti-6Al-4V-Ru, whereas 2-3 wt.% is sufficient for the lower strength Ti-3Al-2.5V-Ru alloy. Although HCl-acidification aggravated methanolic SCC, intermixing of methanol with crude oil or pure hydrocarbons, H{sub 2}S gas saturation, and/or increasing temperature diminished cracking susceptibility in these alloy tubulars.

Effect of Vacuum-Sintering Temperature on Magnetic and Mechanical Properties of TiC-TiN-Ni-Mo-C Cermets

NASA Astrophysics Data System (ADS)

Zhang, Man; Yang, Qingqing; Xiong, Weihao; Zhou, Shiquan; Wang, Shengqing; Luo, Haifeng; Ruan, Linji

2018-05-01

The effect of vacuum-sintering temperature (T vs ), ranging from 1390 °C to 1470 °C, on magnetic and mechanical properties of TiC-10TiN-30Ni-6Mo-4C (mol pct) cermet was investigated in the present article. Room-temperature (RT) magnetization and maximum susceptibility decreased with increasing T vs up to 1450 °C, and then increased. This was mainly attributed to the fact that Ti content in the Ni-based binder phase increased with increasing T vs up to 1450 °C, suppressing ferromagnetism of the Ni matrix. RT ferromagnetism disappeared at T vs ≥ 1430 °C. Transverse rupture strength (TRS) reached a peak value at T vs = 1430 °C, and hardness did not significantly vary with T vs .

Preparation of TiO₂/Carbon Nanotubes/Reduced Graphene Oxide Composites with Enhanced Photocatalytic Activity for the Degradation of Rhodamine B.

PubMed

Huang, Yanzhen; Chen, Dongping; Hu, Xinling; Qian, Yingjiang; Li, Dongxu

2018-06-13

In this report, ternary titanium dioxide (TiO₂)/carbon nanotubes (CNTs)/reduced graphene oxide (rGO) composites were fabricated by a facile and environmentally friendly one-pot solvethermal method for the removal of Rhodamine B (RhB). Its structures were represented by X-ray powder diffraction (XRD), Raman spectrometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic performance was tested by the degradation efficiency of RhB under UV-vis light irradiation. The experimental results indicated that photocatalytic activity improved as the ratio of CNTs:TiO₂ ranged from 0.5% to 3% but reduced when the content increased to 5% and 10%, and the TiO₂/CNTs/rGO-3% composites showed superior photocatalytic activity compared with the binary ones (i.e., TiO₂/CNTs, TiO₂/rGO) and pristine TiO₂. The rate constant k of the pseudo first-order reaction was about 1.5 times that of TiO₂. The improved photocatalytic activity can be attributed to the addition of rGO and CNTs, which reduced the recombination of photo-induced electron-hole pairs, and the fact that CNTs and rGO, with a high specific surface area and high adsorption ability to efficiently adsorb O₂, H₂O and organics, can increase the hydroxyl content of the photocatalyst surface.

Influence of Sn doping in BaSnxTi1-xO3 ceramics on microstructural and dielectric properties

NASA Astrophysics Data System (ADS)

Ansari, Mohd. Azaj; Sreenivas, K.

2018-05-01

BaSnxTi1-x O3 solid solutions with varying Sn content (x = 0.00, 0.05, 0.15, 0.25) prepared by solid state reaction method have been studied for their structural and dielectric properties. X-ray diffraction and Raman spectroscopic analysis show composition induced modifications in the crystallographic structure, and with increasing Sn content the structure changes from tetragonal to cubic structure. The tetragonal distortion decreases with increasing Sn, and the structure becomes purely cubic for x =0.25. Changes in the structure are reflected in the temperature dependent dielectric properties. For increasing Sn content the peak dielectric constant is found to increase and the phase transition temperature (Tc) decreases to lower temperature. The purely cubic structure with x=0.25 shows a diffused phased transition.

Improved light-induced cell detachment on rutile TiO₂ nanodot films.

PubMed

Cheng, Kui; Sun, Yu; Wan, Hongping; Wang, Xiaozhao; Weng, Wenjian; Lin, Jun; Wang, Huiming

2015-10-01

Anatase TiO2 nanodot films have been found to be able to release cells under light illumination with excellent efficiency and safety. In the present study, we investigated the effects of rutile contents in TiO2 nanodot films on such light induced cell detachment behavior. The results showed that TiO2 nanodot films with different contents of rutile phase have been prepared successfully. The content of rutile phase increased with the increase in calcination temperature. All films possessed good cell adhesion but there was a decrease in cell proliferation with the increasing content of rutile phase. Single cell detachment assay showed that the films with high rutile contents (calcined at 900°C and 1100°C) showed better cell detachment performance. That was ascribed to the changes of the secondary structure of extracellular proteins adsorbed on the nanodot surface after ultraviolet (365 nm, UV365) illumination. In addition, cell sheets detached through UV365 illumination maintained high activity and could be further used in tissue engineering. The present work showed that the existence of rutile phase is helpful in cell detachment behavior and it could be utilized to optimize light-induced cell detachment behavior. This work discovers that the presence of rutile phase in TiO2 nanodot films could improve the light-induced cell detachment behavior, although rutile phase is inferior to anatase phase on light induced superhydrophilicity. That strongly supported that the behaviors of adsorbed proteins are crucial in acquiring cell sheet with light illumination. In fact, the state and behavior of adsorbed protein greatly affect the interaction between biomaterials and living cells. Therefore, we consider this work is not only important in harvesting cells or cell sheets through light illumination, but also helpful in further understanding of interaction between biomaterials and cells. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of laser welding parameters on the austenite and martensite phase fractions of NiTi

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliveira, J.P., E-mail: jp.oliveira@campus.fct.unl

Although laser welding is probably the most used joining technique for NiTi shape memory alloys there is still a lack of understanding about the effects of laser welding parameters on the microstructural induced changes: in both the heat affected and fusion zones martensite may be present, while the base material is fully austenitic. Synchrotron X-ray diffraction was used for fine probing laser welded NiTi joints. Through Rietveld refinement the martensite and austenite phase fractions were determined and it was observed that the martensite content increases towards the weld centreline. This is related to a change of the local transformation temperaturesmore » on these regions, which occurs due to compositional variation in those regions. The martensite phase fraction in the thermally affected regions may have significant implications on functional properties on these joints. - Highlights: •Synchrotron X-ray diffraction was used for fine probing of the microstructure in laser welded NiTi joints. •Rietveld refinement allowed to determine the content of martensite along the heat affected and fusion zones. •The martensite content increases from the base material towards the weld centreline.« less

Effect of in-situ TiC particulate on the wear resistance of spray-deposited 7075 Al matrix composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Feng; Liu Huimin; Yang Bin

2005-05-15

TiC reinforced 7075 Al matrix composites have been fabricated by a melt in-situ reaction spray deposition. The microstructures of spray-deposited alloys were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dry sliding wear behavior of the alloys was investigated using a pin-on-disc machine under four loads, namely 8.9, 17.8, 26.7 and 35.6 N. It has been found that the wear behavior of the alloys was dependent on the TiC content in the microstructure and the applied load. At a lower load (8.9 N), with increasing TiC content, the wear rate of the alloy was decreased. At amore » higher loads (26.7, 35.6 N), a spray-deposited 7075 Al alloy exhibited superior wear resistance to the 7075/TiC composites.« less

Preparation of Transparent Bulk TiO2/PMMA Hybrids with Improved Refractive Indices via an in Situ Polymerization Process Using TiO2 Nanoparticles Bearing PMMA Chains Grown by Surface-Initiated Atom Transfer Radical Polymerization.

PubMed

Maeda, Satoshi; Fujita, Masato; Idota, Naokazu; Matsukawa, Kimihiro; Sugahara, Yoshiyuki

2016-12-21

Transparent TiO 2 /PMMA hybrids with a thickness of 5 mm and improved refractive indices were prepared by in situ polymerization of methyl methacrylate (MMA) in the presence of TiO 2 nanoparticles bearing poly(methyl methacrylate) (PMMA) chains grown using surface-initiated atom transfer radical polymerization (SI-ATRP), and the effect of the chain length of modified PMMA on the dispersibility of modified TiO 2 nanoparticles in the bulk hybrids was investigated. The surfaces of TiO 2 nanoparticles were modified with both m-(chloromethyl)phenylmethanoyloxymethylphosphonic acid bearing a terminal ATRP initiator and isodecyl phosphate with a high affinity for common organic solvents, leading to sufficient dispersibility of the surface-modified particles in toluene. Subsequently, SI-ATRP of MMA was achieved from the modified surfaces of the TiO 2 nanoparticles without aggregation of the nanoparticles in toluene. The molecular weights of the PMMA chains cleaved from the modified TiO 2 nanoparticles increased with increases in the prolonging of the polymerization period, and these exhibited a narrow distribution, indicating chain growth controlled by SI-ATRP. The nanoparticles bearing PMMA chains were well-dispersed in MMA regardless of the polymerization period. Bulk PMMA hybrids containing modified TiO 2 nanoparticles with a thickness of 5 mm were prepared by in situ polymerization of the MMA dispersion. The transparency of the hybrids depended significantly on the chain length of the modified PMMA on the nanoparticles, because the modified PMMA of low molecular weight induced aggregation of the TiO 2 nanoparticles during the in situ polymerization process. The refractive indices of the bulk hybrids could be controlled by adjusting the TiO 2 content and could be increased up to 1.566 for 6.3 vol % TiO 2 content (1.492 for pristine PMMA).

Facile one-pot synthesis of nickel-incorporated titanium dioxide/graphene oxide composites: Enhancement of photodegradation under visible-irradiation

NASA Astrophysics Data System (ADS)

Pham, Thanh-Truc; Nguyen-Huy, Chinh; Shin, Eun Woo

2016-07-01

Nickel (Ni)-incorporated titanium dioxide (TiO2)/graphene oxide composite photocatalysts were prepared by anchoring the TiO2 and Ni onto the surface of graphene oxide (GO) sheets by a straightforward microwave-assisted, one-pot method for the first time. The as-prepared composite photocatalysts with high Ni content (40-50 wt%) showed good adsorption capacity in the dark and high reaction rate constants under visible illumination while the composite photocatalysts with low Ni content (5-10 wt%) exhibited weak activity. An anatase phase, a small amount of rutile phase and Ni metal were detected using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Raman measurements identified a small fraction of NiTiO3 only at high Ni content. The formation of NiTiO3 and the increase in the specific surface area (SSA) for 40 and 50 wt% Ni-loaded catalysts improved the adsorption capacity and photocatalytic activity upon exposure to visible light, resulting in very effective removal of dye contaminants under visible light irradiation. Increasing the Ni content up to 40 and 50 wt% induced not only a structural change affording high porosity but also a narrowing of the band gap to 2.51 eV. Meanwhile, the presence of GO in the composite photocatalysts inhibited the agglomeration of Ni particles even at high Ni content, resulting in similar Ni particle sizes regardless of the Ni content. At the same time, Ni metal accelerated the reduction of the GO sheets, as evidenced by the Raman data.

Morphology and crystalline phase study of electrospun TiO2 SiO2 nanofibres

NASA Astrophysics Data System (ADS)

Ding, Bin; Kim, Hakyong; Kim, Chulki; Khil, Myungseob; Park, Soojin

2003-05-01

Nanofibres of TiO2-SiO2 (Ti:Si = 50: 50 mol%) with diameters of 50-400 nm were prepared by calcining electrospun nanofibres of polyvinyl acetate (PVac)/titania-silica composite as precursor. These PVac/titania-silica hybrid nanofibres were obtained from a homogenous solution of PVac with a sol-gel of titanium isopropoxide (TiP) and tetraethoxysilane by using the electrospinning technique. The nanofibres were characterized by scanning electron microscopy (SEM), wide-angle x-ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy and Brunauer-Emmett-Teller (BET) surface area. SEM, WAXD and FTIR results indicated that the morphology and crystalline phase of TiO2-SiO2 nanofibres were strongly influenced by the calcination temperature and the content of titania and silica in the nanofibres. Additionally, the BET results showed that the surface area of TiO2-SiO2 nanofibres was decreased with increasing calcination temperature and the content of titania and silica in nanofibres.

Preparation and properties of TiC-Ni cermets using Ni-plated TiC

NASA Astrophysics Data System (ADS)

Shin, Soon-Gi

2002-04-01

TiC powders were coated with Ni by a chemical plating technique and the pressed compacts sintered at 1623K. The density of the sintered bodies was 98-99%. Compared with mechanically-mixed powder, Ni-plated TiC powders gave a more uniform microstructure in which TiC particles were well dispersed in the Ni matrix. The cermets exhibited ductile fracture for TiC-70 vol.% Ni and brittle fracture for TiC-30 vol.% Ni. The flexural strength was improved by the homogeneous dispersion of TiC. The thermal expansion coefficient increased with a decrease in Ni content, following a nearly linear law of mixtures on the basis of volume fractions of pure TiC and Ni.

Mechanical and moisture barrier properties of titanium dioxide nanoparticles and halloysite nanotubes reinforced polylactic acid (PLA)

NASA Astrophysics Data System (ADS)

Alberton, J.; Martelli, S. M.; Fakhouri, F. M.; Soldi, V.

2014-08-01

Polylactic acid (PLA) has been larger used in biomedical field due to its low toxicity and biodegradability. The aim of this study was to produce PLLA nanocomposites, by melt extrusion, containing Halloysite nanotubes (HNT) and/or titanium dioxide (TiO2) nanoparticles. Immediately after drying, PLLA was mechanically homogenized with the nanofillers and then melt blended using a single screw extruder (L/D = 30) at a speed of 110 rpm, with three heating zones in which the following temperatures were maintained: 150, 150 and 160°C (AX Plasticos model AX14 LD30). The film samples were obtained by compression molding in a press with a temperature profile of 235 ± 5°C for 2.5 min, after pressing, films were cooled up to room temperature. The mechanical tests were performed according to ASTM D882-09 and the water vapor permeability (WVP) was measured according to ASTM E-96, in triplicate. The tensile properties indicated that the modulus was improved with increased TiO2 content up to 1g/100g PLLA. The Young's modulus (YM) of the PLA was increased from 3047 MPa to 3222 MPa with the addition of 1g TiO2/100g PLLA. The tensile strength (TS) of films increases with the TiO2 content. In both cases, the YM and TS are achieved at the 1% content of TiO2 and is due to the reinforcing effect of nanoparticles. Pristine PLA showed a strain at break (SB) of 3.56%, while the SB of nanocomposites were significant lower, for instance the SB of composite containing 7.5 g HNT/100g PLLA was around 1.90 %. The WVP of samples was increased by increasing the nano filler content. It should be expected that an increase of nanofiller content would decrease the mass transfer of water molecules throughout the samples due to the increase in the way water molecules will have to cross to permeate the material. However, this was not observed. Therefore, this result can be explained considering the molecular structure of both fillers, which contain several hydroxyl groups in the surface, making the end material more hydrophilic.

Studies on the effect of acid treated TiO{sub 2} on the electrical and tensile properties of hexanoyl chitosan-polystyrene-LiCF{sub 3}SO{sub 3} composite polymer electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanif, Nur Shazlinda Muhammad; Shahril, Nur Syuhada Mohd; Azmar, Amisha

2015-08-28

Composite polymer electrolytes (CPEs) comprised of hexanoyl chitosan:polystyrene (90:10) blend, lithium triflouromethanesulfonate (LiCF{sub 3}SO{sub 3}) salt and titanium oxide (TiO{sub 2}) filler were prepared by solution casting technique. The TiO{sub 2} fillers were treated with 2% sulphuric acid (H{sub 2}SO{sub 4}) aqueous solution. The effect of acid treated TiO{sub 2} on the electrical and tensile properties of the electrolytes were investigated. Acid treated TiO{sub 2} decreased the electrolyte conductivity. Both the dielectric constant and dielectric loss decrease with increasing frequency and increases with increasing temperature. Relaxation times for ionic carriers were extracted from the loss tangent maximum peak at variousmore » temperatures. A distribution of relaxation time implied the non-Debye response. At all frequencies, ac conductivity increases with increasing temperature. An enhancement in the Young’s modulus was observed with the addition of TiO{sub 2}. The Young’s modulus increases with increasing TiO{sub 2} content. This is discussed using the percolation concept.« less

Characterization of Ternary NiTiPt High-Temperature Shape Memory Alloys

NASA Technical Reports Server (NTRS)

Rios, Orlando; Noebe, Ronald; Biles, Tiffany; Garg, Anita; Palczer, Anna; Scheiman, Daniel; Seifert, Hans Jurgen; Kaufman, Michael

2005-01-01

Pt additions substituted for Ni in NiTi alloys are known to increase the transformation temperature of the alloy but only at fairly high Pt levels. However, until now only ternary compositions with a very specific stoichiometry, Ni50-xPtxTi50, have been investigated and then only to very limited extent. In order to learn about this potential high-temperature shape memory alloy system, a series of over twenty alloys along and on either side of a line of constant stoichiometry between NiTi and TiPt were arc melted, homogenized, and characterized in terms of their microstructure, transformation temperatures, and hardness. The resulting microstructures were examined by scanning electron microscopy and the phase compositions quantified by energy dispersive spectroscopy."Stoichiometric" compositions along a line of constant stoichiometry between NiTi to TiPt were essentially single phase but by any deviations from a stoichiometry of (Ni,Pt)50Ti50 resulted in the presence of at least two different intermetallic phases, depending on the overall composition of the alloy. Essentially all alloys, whether single or two-phase, still under went a martensitic transformation. It was found that the transformation temperatures were depressed with initial Pt additions but at levels greater than 10 at.% the transformation temperature increased linearly with Pt content. Also, the transformation temperatures were relatively insensitive to alloy stoichiometry within the range of alloys examined. Finally, the dependence of hardness on Pt content for a series of Ni50-xPtxTi50 alloys showed solution softening at low Pt levels, while hardening was observed in ternary alloys containing more than about 10 at.% Pt. On either side of these "stoichiometric" compositions, hardness was also found to increase significantly.

Microstructural and Mechanical Characterization of Ti-12Mo-6Zr Biomaterials Fabricated by Spark Plasma Sintering

NASA Astrophysics Data System (ADS)

Daoush, Walid Mohamed Rashad Mohamed; Park, Hee Sup; Inam, Fawad; Lim, Byung Kyu; Hong, Soon Hyung

2015-03-01

Ti-12Mo-6Zr/Al2O3 (titanium biomaterial) was prepared by a powder metallurgy route using Spark Plasma Sintering (SPS). Ti, Mo, and Zr powders were mixed by wet milling with different content of alumina nanoparticles (up to 5 wt pct) as an oxide dispersion strengthening phase. Composite powder mixtures were SPSed at 1273 K (1000 °C) followed by heat treatment and quenching. Composite powders, sintered materials, and heat-treated materials were examined using optical and high-resolution electronic microscopy (scanning and transmission) and X-ray diffraction to characterize particle size, surface morphology, and phase identifications for each composition. All sintered materials were evaluated by measuring density, Vickers hardness, and tensile properties. Fully dense sintered materials were produced by SPS and mechanical properties were found to be improved by subsequent heat treatment. The tensile properties as well as the hardness were increased by increasing the content of Al2O3 nanoparticles in the Ti-12Mo-6Zr matrix.

Optical and transport properties of LaTi{sub 1−x}M{sub x}(O,N){sub 3±δ} (x=0; 0.1, M=Nb{sup 5+}, W{sup 6+}) thin films prepared by plasma ammonolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maegli, Alexandra E.; Sagarna, Leyre; Populoh, Sascha

2014-03-15

Oxynitride thin films of composition LaTi{sub 1−x}M{sub x}(O,N){sub 3±δ} with x=0; 0.1 and M=Nb{sup 5+}, W{sup 6+} were prepared by nitridation via microwave-induced plasma (MIP) ammonolysis, which allowed keeping the nitridation time short (16 min). The higher possible oxidation states of the B-site substituents (Nb{sup 5+}, W{sup 6+}) with respect to Ti{sup 4+} caused higher N content for LaTi{sub 0.9}Nb{sub 0.1}(O,N){sub 3±δ} and LaTi{sub 0.9}W{sub 0.1}(O,N){sub 3±δ} compared to LaTiO{sub 2}N due to charge-compensation. XPS O 1s and N 1s core level and valence band spectra evidenced for increasing N content in the order LaTiO{sub 2}N

Virus inactivation by silver doped titanium dioxide nanoparticles for drinking water treatment.

PubMed

Liga, Michael V; Bryant, Erika L; Colvin, Vicki L; Li, Qilin

2011-01-01

Photocatalytic inactivation of viruses and other microorganisms is a promising technology that has been increasingly utilized in recent years. In this study, photocatalytic silver doped titanium dioxide nanoparticles (nAg/TiO(2)) were investigated for their capability of inactivating Bacteriophage MS2 in aqueous media. Nano-sized Ag deposits were formed on two commercial TiO(2) nanopowders using a photochemical reduction method. The MS2 inactivation kinetics of nAg/TiO(2) was compared to the base TiO(2) material and silver ions leached from the catalyst. The inactivation rate of MS2 was enhanced by more than 5 fold depending on the base TiO(2) material, and the inactivation efficiency increased with increasing silver content. The increased production of hydroxyl free radicals was found to be responsible for the enhanced viral inactivation. Copyright © 2010 Elsevier Ltd. All rights reserved.

FABRICATION OF IN SITUFe-Ti-B COMPOSITE COATING BY LASER CLADDING

NASA Astrophysics Data System (ADS)

Du, Baoshuai

2013-06-01

Laser cladding was applied to deposit in situFe-Ti-B composite coatings on mild carbon steel with precursor of ferrotitanium, ferroboron and pure Fe alloy powders. The composite coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA). Wear resistance of the laser-cladded Fe-Ti-B coatings was evaluated under dry sliding condition at room temperature using block-on-ring wear tester. Results indicate that in situ reinforcements of TiB2 and Fe2B can be synthesized in the Fe-Ti-B coatings. The amount of TiB2 increases with the increase of content of ferrotitanium and ferroboron in the precursor. Reinforcements are formed through the liquid-precipitation route following the solidification path of the Fe-Ti-B system. Hardness and wear properties of the coatings improved significantly in comparison to the as-received substrate due to the presence of hard reinforcements.

Simulation of Zr content in TiZrCuNi brazing filler metal for Ti6Al4V alloy

NASA Astrophysics Data System (ADS)

Yue, Xishan; Xie, Zonghong; Jing, Yongjuan

2017-07-01

To optimize the Zr content in Ti-based filler metal, the covalent electron on the nearest atoms bond in unit cell ( n A u-v ) with Ti-based BCC structure was calculated, in which the brazing temperature was considered due to its influence on the lattice parameter. Based on EET theory (The Empirical Electron Theory for solid and molecules), n_{{A}}^{{u - v}} represents the strength of the unit cell with defined element composition and structure, which reflects the effect from solid solution strengthening on the strength of the unit cell. For Ti-Zr-15Cu-10Ni wt% filler metal, it kept constant as 0.3476 with Zr as 37.5˜45 wt% and decreased to 0.333 with Zr decreasing from 37.5 to 25 wt%. Finally, it increased up to 0.3406 with Zr as 2˜10 wt%. Thus, Ti-based filler metal with Zr content being 2˜10 wt% is suggested based on the simulation results. Moreover, the calculated covalent electron of n A u-v showed good agreement with the hardness of the joint by filler 37.5Zr and 10Zr. The composition of Ti-10Zr-15Cu-10Ni wt% was verified in this study with higher tensile strength of the brazing joint and uniform microstructure of the interface.

Magnetic properties of CeFe11-xCoxTi with ThMn12 structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, C; Pinkerton, FE; Herbst, JF

2014-05-07

A series of novel alloys CeFe11-xCoxTi (0 <= x <= 11) with ThMn12 structure has been successfully prepared by melt-spinning. The Curie temperature T-c increases with Co content x, reaching a maximum of 689 degrees C at x = 9 and declining to 664 degrees C at complete Co filling (x = 11). The room temperature saturation magnetization 4 pi M-s and magnetocrystalline anisotropy H-a have been estimated by fitting the first quadrant demagnetization curve with the Stoner-Wohlfarth model. 4 pi M-s first increases with increasing Co up to x = 3, then decrease. H-a has a complex dependence onmore » Co content, which is indicative of a change in the easy magnetization direction from axis to plane and back as the Co content increases. (C) 2014 AIP Publishing LLC.« less

Effect of the existing form of Cu element on the mechanical properties, bio-corrosion and antibacterial properties of Ti-Cu alloys for biomedical application.

PubMed

Zhang, Erlin; Wang, Xiaoyan; Chen, Mian; Hou, Bing

2016-12-01

Ti-Cu alloys have exhibited strong antibacterial ability, but Ti-Cu alloys prepared by different processes showed different antibacterial ability. In order to reveal the controlling mechanism, Ti-Cu alloys with different existing forms of Cu element were prepared in this paper. The effects of the Cu existing form on the microstructure, mechanical, corrosion and antibacterial properties of Ti-Cu alloys have been systematically investigated. Results have shown that the as-cast Ti-Cu alloys showed a higher hardness and mechanical strength as well as a higher antibacterial rate (51-64%) but a relatively lower corrosion resistance than pure titanium. Treatment at 900°C/2h (T4) significantly increased the hardness and the strength, improved the corrosion resistance but had little effect on the antibacterial property. Treatment at 900°C/2h+400°C/12h (T6) increased further the hardness and the mechanical strength, improved the corrosion resistance and but also enhanced the antibacterial rate (>90%) significantly. It was demonstrated that the Cu element in solid solution state showed high strengthening ability but low antibacterial property while Cu element in Ti2Cu phase exhibited strong strengthening ability and strong antibacterial property. Ti2Cu phase played a key role in the antibacterial mechanism. The antibacterial ability of Ti-Cu alloy was strongly proportional to the Cu content and the surface area of Ti2Cu phase. High Cu content and fine Ti2Cu phase would contribute to a high strength and a strong antibacterial ability. Copyright © 2016 Elsevier B.V. All rights reserved.

Optical Properties of Nitrogen-Substituted Strontium Titanate Thin Films Prepared by Pulsed Laser Deposition

PubMed Central

Marozau, Ivan; Shkabko, Andrey; Döbeli, Max; Lippert, Thomas; Logvinovich, Dimitri; Mallepell, Marc; Schneider, Christof W.; Weidenkaff, Anke; Wokaun, Alexander

2009-01-01

Perovskite-type N‑substituted SrTiO3 thin films with a preferential (001) orientation were grown by pulsed laser deposition on (001)-oriented MgO and LaAlO3 substrates. Application of N2 or ammonia using a synchronized reactive gas pulse produces SrTiO3-x:Nx films with a nitrogen content of up to 4.1 at.% if prepared with the NH3 gas pulse at a substrate temperature of 720 °C. Incorporating nitrogen in SrTiO3 results in an optical absorption at 370‑460 nm associated with localized N(2p) orbitals. The estimated energy of these levels is ≈2.7 eV below the conduction band. In addition, the optical absorption increases gradually with increasing nitrogen content.

Micro-nano filler metal foil on vacuum brazing of SiCp/Al composites

NASA Astrophysics Data System (ADS)

Wang, Peng; Gao, Zeng; Niu, Jitai

2016-06-01

Using micro-nano (Al-5.25Si-26.7Cu)- xTi (wt%, x = 1.0, 1.5, 2.0, 2.5 and 3.0) foils as filler metal, the research obtained high-performance joints of aluminum matrix composites with high SiC particle content (60 vol%, SiCp/Al-MMCs). The effect of brazing process and Ti content on joint properties was investigated, respectively. The experimental results indicate that void free dense interface between SiC particle and metallic brazed seam with C-Al-Si-Ti product was readily obtained, and the joint shear strength enhanced with increasing brazing temperature from 560 to 580 °C or prolonging soaking time from 10 to 90 min. Sound joints with maximum shear strength of 112.5 MPa was achieved at 580 °C for soaking time of 90 min with (Al-5.25Si-26.7Cu)-2Ti filler, where Ti(AlSi)3 intermetallic is in situ strengthening phase dispersed in the joint and fracture occured in the filler metal layer. In this research, the beneficial effect of Ti addition into filler metal on improving wettability between SiC particle and metallic brazed seam was demonstrated, and capable welding parameters were broadened for SiCp/Al-MMCs with high SiC particle content.

Development of High Strength Ni-Cu-Zr-Ti-Si-Sn In-Situ Bulk Metallic Glass Composites Reinforced by Hard B2 Phase

NASA Astrophysics Data System (ADS)

Park, Hyo Jin; Hong, Sung Hwan; Park, Hae Jin; Kim, Young Seok; Kim, Jeong Tae; Na, Young Sang; Lim, Ka Ram; Wang, Wei-Min; Kim, Ki Buem

2018-03-01

In the present study, the influence of atomic ratio of Zr to Ti on the microstructure and mechanical properties of Ni-Cu-Zr-Ti-Si-Sn alloys is investigated. The alloys were designed by fine replacement of Ti for Zr from Ni39Cu20Zr36-xTixSi2Sn3. The increase of Ti content enhances glass forming ability of the alloy by suppression of formation of (Ni, Cu)10(Zr, Ti)7 phase during solidification. With further increasing Ti content up to 24 at.%, the B2 phase is introduced in the amorphous matrix with a small amount of B19' phase from alloy melt. The bulk metallic glass composite containing B2 phase with a volume fraction of 10 vol% exhibits higher fracture strength ( 2.5 GPa) than that of monolithic bulk metallic glass ( 2.3 GPa). This improvement is associated to the individual mechanical characteristics of the B2 phase and amorphous matrix. The B2 phase exhibits higher hardness and modulus than those of amorphous matrix as well as effective stress accommodation up to the higher stress level than the yield strength of amorphous matrix. The large stress accommodation capacity of the hard B2 phase plays an important factor to improve the mechanical properties of in situ Ni-based bulk metallic glass composites.

Photocatalytic degradation of methylene blue on Sn-doped titania nanoparticles synthesized by solution combustion route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhange, P.D., E-mail: pallavi.ncl@gmail.com; Awate, S.V.; Gholap, R.S.

2016-04-15

Highlights: • Series of Sn-doped titania nanoparticles were prepared by solution combustion synthesis method. • Sn-doped titania nanoparticles were tested for degradation of MB under UV light irradiation. • The maximum Sn doping in the TiO{sub 2} lattice is found to be less than 10%. • The crystallite size decreases with increase in the Sn content. • The doping of Sn into TiO{sub 2} lattice hinders the recombination of electrons and holes thus enhance the photocatalytic activity. - Abstract: Series of tin-doped titania nanoparticles with varying tin content in the range 0–20 mol% have been prepared by solution combustion synthesismore » route using urea as a fuel. The structure, surface morphology and optical activity of Sn-doped TiO{sub 2} nanoparticles were investigated by various analytical techniques such as powder XRD, SEM, TEM, UV–vis and N{sub 2} adsorption study. The crystalline structures of the various phases were studied by rietveld refinement of the XRD data. The photocatalytic performance of Sn-doped titania nanoparticles were tested for degradation of MB under UV and visible light irradiation. The results reveal that the photocatalytic activity increases with increase in tin content which may be due to decrease in crystallite size with increase in surface area. The doping of Sn into TiO{sub 2} lattice hinders the recombination of electrons and holes thus enhance the quantum efficiency of photocatalytic reaction.« less

Temporal changes of flavour and texture in cooked bologna type sausages as affected by fat and salt content.

PubMed

Ventanas, Sonia; Puolanne, Eero; Tuorila, Hely

2010-07-01

Temporal changes of flavour (mushroom-like and saltiness) and texture (juiciness) in cooked bologna type sausages with different fat and salt content and containing selected volatile compounds (100 mg kg(-1) of 1-octen-3-ol and 200 mg kg(-1) of 2,6-dimethylpyrazine) were evaluated using time-intensity (TI) method. Preceding the TI study, descriptive profiles of sausages were determined. Release of volatiles was analysed by solid-phase microextraction coupled to gas chromatography-mass spectrometry (SPME-GC-MS) and an instrumental texture analysis was also performed. Chromatographic results obtained for 1-octen-3-ol were strongly correlated with the intensity perception of the linked odour and flavour (mushroom). Modifications of sausages matrix in terms of fat and salt content differently affected the dynamic perception of mushroom flavour, saltiness and juiciness. NaCl contributed to increasing release of 1-octen-3-ol (salting-out effect) confirmed by SPME analysis as well as the intensity and duration of the related flavour (mushroom) evaluated by TI. Similarly, NaCl increased the temporal perception of both saltines and juiciness of sausages. Increase in fat content led to a higher retention of 1-octen-3-ol (lipophilic compound) and thus to a less intense and shorter duration of mushroom flavour. Moreover, fat contributed to a more intense and a longer juiciness of sausages. These results highlight the feasibility of TI technique to evaluate changes in the temporal flavour and texture perception of sausages caused by modification of matrix composition. Copyright 2010 Elsevier Ltd. All rights reserved.

Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites

NASA Astrophysics Data System (ADS)

Prakash, Jai; Kumar, Promod; Harris, R. A.; Swart, Chantel; Neethling, J. H.; Janse van Vuuren, A.; Swart, H. C.

2016-09-01

We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples.

The effect of heat treatment on superhydrophilicity of TiO2 nano thin films

NASA Astrophysics Data System (ADS)

Ashkarran, A. A.; Mohammadizadeh, M. R.

2007-11-01

TiO2 thin films were synthesized by the sol-gel method and spin coating process. The calcination temperature was changed from 100 to 550°C. XRD patterns show increasing the content of polycrystalline anatase phase with increasing the calcination temperature. The AFM results indicate granular morphology of the films, which particle size changes from 22 to 166nm by increasing the calcination temperature. The RBS, EDX and Raman spectroscopy of the films show the ratio of Ti:O ~0.5, and diffusion of sodium ions from substrate into the layer, by increasing the calcination temperature. The UV-vis spectroscopy of the films indicates a red shift by increasing the calcination temperature. The contact angle meter experiment shows that superhydrophilicity of the films depends on the formation of anatase crystal structure and diffused sodium content from substrate to the layer. The best hydrophilicity property was observed at 450°C calcination temperature, where the film is converted to a superhydrophilic surface after 10min under 2mW/cm2 UV irradiation. Water droplet on TiO2 thin film on Si(111), Si(100), and quartz substrates is spread to smaller angles rather than glass and polycrystalline Si substrates under UV irradiation.

Microstructure and Properties of Ternary Cu-Ti-Sn Alloy

NASA Astrophysics Data System (ADS)

Wang, Xianhui; Chen, Chunyu; Guo, Tingting; Zou, Juntao; Yang, Xiaohong

2015-07-01

The effect of Sn addition and heat treatment on the microstructure and properties of Cu-3Ti and Cu-2Ti alloys was studied. The microstructure and phase constituents were characterized by an optical microscope, x-ray diffractometer, and transmission electron microscope, and the electrical conductivity and hardness were determined as well. The results show that the as-cast microstructure of Cu-Ti-Sn alloys consists of α-Cu(Ti,Sn) and primary CuSn3Ti5 intermetallic compound. CuSn3Ti5 phase has a hexagonal structure with the lattice parameters a = 0.81737 nm, b = 0.81737 nm, and c = 0.55773 nm. With the increase of aging time, the electrical conductivity progressively increases, while the hardness increases and then decreases. After aging at 450 °C for 8 h, Cu-3Ti-2Sn alloy has an electrical conductivity of 23.1 MS/m and a hardness of 134.5 HV, and the electrical conductivity and hardness of Cu-2Ti-2Sn alloy are 21.5 MS/m and 119.3 HV, respectively. An appropriate aging is beneficial for the precipitation of coherent metastable β'-Cu4Ti phase, which can strengthen Cu-3Ti-2Sn and Cu-2Ti-2Sn alloys. However, a prolonged aging time results in the decrease of hardness due to the formation of incoherent equilibrium β-Cu3Ti phase. The presence of CuSn3Ti5 phase reduces the solute Ti content in the copper matrix and, thus, gives rise to the increase of the electrical conductivity of Cu-Ti-Sn alloys.

A TiO2 abundance map for the northern maria

NASA Technical Reports Server (NTRS)

Johnson, T. V.; Saunders, R. S.; Matson, D. L.; Mosher, J. A.

1977-01-01

A map of TiO2 abundance for most of the northern maria is presented. The telescopic data base used is the 0.38/0.56-micron ratio mosaic from Johnson et at. (1977). The titanium content has been estimated using the correlation established by Charette et al. (1974). The combination of observational, processing, and calibration errors indicates that the TiO2 map is accurate to + or - 2% (wt% TiO2) for high TiO2 content (more than 5%) and + or - 1% for low values of TiO2. Analysis of the lunar sample and telescopic data suggests strongly that the spectral parameter mapped is sensitive primarily to TiO2 abundance in the range 3-9% and does not correlate directly with iron content. It is suggested, however, that for the low TiO2 mare regions (less than 2-3% TiO2) there may be a relation between the spectral ratio and iron content and that some of the reddest mare areas in the Imbrium region may have low iron contents as well as low titanium abundances.

Magnetic Properties of Hematite-Titania Nanocomposites from Ilmenite Leachant Solutions

NASA Astrophysics Data System (ADS)

Sanad, M. M. S.; Rashad, M. M.

2017-07-01

Different Fe2O3/TiO2 nanocomposite ratios have been auto-synthesized from the leaching solution of Egyptian ilmenite ore with and without solvent extraction of soluble iron ions. Hydrolysis-hydrothermal strategy was then implemented for preparation of Fe2O3-TiO2 nanocomposites. The x-ray diffraction results indicated that rutile and hematite were only found at high iron oxide content. Meanwhile, anatase and hematite were the predominant phases at low iron oxide content. High-resolution transmission electron microscopy investigations exhibited nano-rods like morphology and the space lattice distances of TiO2 and Fe2O3 were clearly estimated. Moreover, the chemical composition of different Fe2O3-TiO2 nanocomposites was also elucidated using energy dispersive spectroscopy and Fourier transform infrared analyses techniques. The values of saturation magnetization ( M s) and remanent magnetization ( M r) were noticeably increased by 17.5% and 18.4% with increasing the Fe2O3/TiO2 molar ratio from 1.0 to 3.0, respectively. Field cooling-warming magnetization studies showed that the Morin transition temperature ( T M = 200 K) was consistent with the previously published values.

Optimized composition of nanocomposite scaffolds formed from silk fibroin and nano-TiO2 for bone tissue engineering.

PubMed

Johari, N; Madaah Hosseini, H R; Samadikuchaksaraei, A

2017-10-01

Natural silk fibroin (SF) polymer has biomedical and mechanical properties as a biomaterial for bone tissue engineering scaffolds. Freeze-dried porous nanocomposite scaffolds were prepared from silk fibroin and titanium dioxide (TiO 2 ) nanoparticles as a bioactive reinforcing agent by a phase separation method. In order to fabricate SF/TiO 2 scaffolds, 5, 10, 15 and 20wt% of the TiO 2 were added to the SF. The phase structure, functional groups and morphology of the scaffolds were evaluated using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy techniques, respectively. Porosity of the scaffolds was measured by Archimedes' Principle. In addition, mechanical properties of prepared scaffolds were evaluated by measuring the compressive strength and compressive modulus. The bioactivity property of these scaffolds was examined for 7, 14, 21 and 28days immersion in simulated body fluid (SBF) at 37°C and the in vitro degradation was studied by incubation in phosphate buffered saline (PBS) at 37°C and pH7.4 for up to 30days. Moreover, the scaffolds' biocompatibility was evaluated by seeding and culture of SaOS-2 osteoblast-like cells and assessment of their proliferation with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Results showed that the prepared scaffolds had directional porosity and the reduction of porosity in composite scaffolds with higher contents of TiO 2 nanoparticles resulted to an improvement of the mechanical strength. The macroporous structures with open interconnected and directional pores were successfully obtained without applying any porogen or inorganic solvent. The bioactivity of these scaffolds was confirmed by scanning electron microscopy (SEM) showing surface crystallization of the apatite layer proportional to the duration of immersion in the SBF and the degradation rate of scaffolds were increased by increasing the TiO 2 content. The osteoblast-like cells showed a high attachment and proliferation on these scaffolds and their viability was increased with increasing the SF content. Finally, an optimum composition of SF/TiO 2 nanocomposite scaffolds was selected. Copyright © 2017 Elsevier B.V. All rights reserved.

Ti-Si-C thin films produced by magnetron sputtering: correlation between physical properties, mechanical properties and tribological behavior.

PubMed

Cunha, L; Vaz, F; Moura, C; Munteanu, D; Ionescu, C; Rivière, J P; Le Bourhis, E

2010-04-01

Ti-Si-C thin films were deposited onto silicon, stainless steel and high-speed steel substrates by magnetron sputtering, using different chamber configurations. The composition of the produced films was obtained by Electron Probe Micro-Analysis (EPMA) and the structure by X-ray diffraction (XRD). The hardness and residual stresses were obtained by depth-sensing indentation and substrate deflection measurements (using Stoney's equation), respectively. The tribological behavior of the produced films was studied by pin-on-disc. The increase of the concentration of non-metallic elements (carbon and silicon) caused significant changes in their properties. Structural analysis revealed the possibility of the coexistence of different phases in the prepared films, namely Ti metallic phase (alpha-Ti or beta-Ti) in the films with higher Ti content. The coatings with highest carbon contents, exhibited mainly a sub-stoichiometric fcc NaCI TiC-type structure. These structural changes were also confirmed by resistivity measurements, whose values ranged from 10(3) omega/sq for low non-metal concentration, up to 10(6) omega/sq for the highest metalloid concentration. A strong increase of hardness and residual stresses was observed with the increase of the non-metal concentration in the films. The hardness (H) values ranged between 11 and 27 GPa, with a clear dependence on both crystalline structure and composition features. Following the mechanical behavior, the tribological results showed similar trends, with both friction coefficients and wear revealing also a straight correlation with the composition and crystalline structure of the coatings.

Effect of Nitrogen Content on Physical and Chemical Properties of TiN Thin Films Prepared by DC Magnetron Sputtering with Supported Discharge

NASA Astrophysics Data System (ADS)

Kavitha, A.; Kannan, R.; Gunasekhar, K. R.; Rajashabala, S.

2017-10-01

Amorphous titanium nitride (TiN) thin films have been prepared on silicon (Si) and glass substrates by direct-current (DC) reactive magnetron sputtering with a supported discharge (triode). Nitrogen gas (N2) at partial pressure of 0.3 Pa, 0.4 Pa, 0.5 Pa, and 0.6 Pa was used to prepare the TiN thin films, maintaining total pressure of argon and N2 of about 0.7 Pa. The chemical, microstructural, optical, and electrical properties of the TiN thin films were systematically studied. Presence of different phases of Ti with nitrogen (N), oxygen (O2), and carbon (C) elements was revealed by x-ray photoelectron spectroscopy characterization. Increase in the nitrogen pressure from 0.3 Pa to 0.6 Pa reduced the optical bandgap of the TiN thin film from 2.9 eV to 2.7 eV. Photoluminescence study showed that TiN thin film deposited at N2 partial pressure of 0.3 Pa exhibited three shoulder peaks at 330 nm, 335 nm, and 340 nm, which disappeared when the sample was deposited with N2 partial pressure of 0.6 Pa. Increase in the nitrogen content decreased the electrical resistivity of the TiN thin film from 3200 μΩ cm to 1800 μΩ cm. Atomic force microscopy studies of the TiN thin films deposited with N2 partial pressure of 0.6 Pa showed a uniform surface pattern associated with accumulation of fine grains. The results and advantages of this method of preparing TiN thin films are also reported.

Cleaner Production of Ti Powder by a Two-Stage Aluminothermic Reduction Process

NASA Astrophysics Data System (ADS)

Zhao, Kun; Wang, Yaowu; Feng, Naixiang

2017-10-01

A two-stage aluminothermic reduction process for preparing Ti powder under vacuum conditions using Na2TiF6 was investigated. An Al-Ti master alloy and a clean cryolite were simultaneously obtained as co-products. The first-stage reduction was an exothermic process that occurred at approximately 660°C. The Al and O contents of the Ti powder product were 0.18 wt.% and 0.35 wt.%, respectively, with an average particle size <74 μm. Ti(IV), Ti(III), and metallic Ti were present in the Ti-containing cryolite produced by the first-stage reduction, at a total content of approximately 3.13 wt.%. After second-stage reduction, the Ti elemental contents of the clean cryolite were reduced to 0.002 wt.%. The Al-Ti master alloy obtained by second-stage reduction was composed of Al and TiAl3. The mechanisms involved in these reduction processes were also examined.

Toxicity of titanium dioxide nanoparticles to Chlorella vulgaris Beyerinck (Beijerinck) 1890 (Trebouxiophyceae, Chlorophyta) under changing nitrogen conditions.

PubMed

Dauda, Suleiman; Chia, Mathias Ahii; Bako, Sunday Paul

2017-06-01

The broad application of titanium dioxide nanoparticles (n-TiO 2 ) in many consumer products has resulted in the release of substantial quantities into aquatic systems. While n-TiO 2 have been shown to induce some unexpected toxic effects on aquatic organisms such as microalgae, the influence of changing nutrient conditions on the toxicity of the metal has not been investigated. We evaluated the toxicity of n-TiO 2 to Chlorella vulgaris under varying nitrogen conditions. Limited nitrogen (2.2μM) decreased growth and biomass (dry weight and pigment content), while lipid peroxidation (malondialdehyde content), glutathione S-transferase activity (GST) and peroxidase (POD) activity were increased. Similarly, exposure to n-TiO 2 under replete nitrogen condition resulted in a general decrease in growth and biomass, while GST and POD activities were significantly increased. The combination of limited nitrogen with n-TiO 2 exposure further decreased growth and biomass, and increased GST and POD activities of the microalga. These results suggest that in addition to the individual effects of each investigated condition, nitrogen limitation makes C. vulgaris more susceptible to the effects of n-TiO 2 with regard to some physiological parameters. This implies that the exposure of C. vulgaris and possibly other green algae to this nanoparticle under limited or low nitrogen conditions may negatively affect their contribution to primary production in oligotrophic aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

The impact of Ti and temperature on the stability of Nb5Si3 phases: a first-principles study

PubMed Central

Papadimitriou, Ioannis; Utton, Claire; Tsakiropoulos, Panos

2017-01-01

Abstract Nb-silicide based alloys could be used at T > 1423 K in future aero-engines. Titanium is an important additive to these new alloys where it improves oxidation, fracture toughness and reduces density. The microstructures of the new alloys consist of an Nb solid solution, and silicides and other intermetallics can be present. Three Nb5Si3 polymorphs are known, namely αNb5Si3 (tI32 Cr5B3-type, D8l), βNb5Si3 (tI32 W5Si3-type, D8m) and γNb5Si3 (hP16 Mn5Si3-type, D88). In these 5–3 silicides Nb atoms can be substituted by Ti atoms. The type of stable Nb5Si3 depends on temperature and concentration of Ti addition and is important for the stability and properties of the alloys. The effect of increasing concentration of Ti on the transition temperature between the polymorphs has not been studied. In this work first-principles calculations were used to predict the stability and physical properties of the various Nb5Si3 silicides alloyed with Ti. Temperature-dependent enthalpies of formation were computed, and the transition temperature between the low (α) and high (β) temperature polymorphs of Nb5Si3 was found to decrease significantly with increasing Ti content. The γNb5Si3 was found to be stable only at high Ti concentrations, above approximately 50 at. % Ti. Calculation of physical properties and the Cauchy pressures, Pugh’s index of ductility and Poisson ratio showed that as the Ti content increased, the bulk moduli of all silicides decreased, while the shear and elastic moduli and the Debye temperature increased for the αNb5Si3 and γNb5Si3 and decreased for βNb5Si3. With the addition of Ti the αNb5Si3 and γNb5Si3 became less ductile, whereas the βNb5Si3 became more ductile. When Ti was added in the αNb5Si3 and βNb5Si3 the linear thermal expansion coefficients of the silicides decreased, but the anisotropy of coefficient of thermal expansion did not change significantly. PMID:28740563

Microstructure, mechanical and fretting wear properties of TiC-stainless steel composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akhtar, F.; Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore; Guo, S.J.

2008-01-15

This study deals with the processing, microstructure, and wear behavior of TiC-reinforced stainless steel matrix composites, containing 50 to 70 wt.% TiC. Powder technology was used to successfully fabricate the composites. The microstructure of the composite was characterized by scanning electron microscopy. The microstructural study revealed that the TiC particles were distributed uniformly in the steel matrix phase. Interface debonding and microcracks were not observed in the composite. The composite hardness increased with TiC content. The fretting wear resistance of the composites was studied against high speed steel. The wear mechanisms are discussed by means of microscopical observations on themore » worn surfaces. The wear was severe at higher wear loads and lower TiC content. Microplowing of the stainless steel matrix was found to be the dominant wear mechanism. Heavy microplowing and rapid removal of material from the wear surface was observed at high wear load. The variation of wear loss with volume fraction and mean free path of the binder phase is also reported.« less

Microstructure and dielectric properties of silver-barium titanate nanocomplex materials by wet chemical approach

NASA Astrophysics Data System (ADS)

Ueno, Shintaro; Sakamoto, Yasunao; Nakashima, Kouichi; Wada, Satoshi

2014-09-01

To develop ceramic capacitors with a high effective dielectric constant, we attempted to fabricate BaTiO3 (BT) complexes with embedded Ag nanoparticles by wet chemical processes. Ag nanoparticle-adsorbed dendritic BT particles, Ag-BT hybrid particles, were synthesized from the sol-gel-derived precursor gel powders containing Ag, Ba, and Ti by hydrothermal treatment. These particles were pressed with BT fillers and TiO2 precursor nanoparticles into green compacts, and then, the green compacts were chemically converted into the Ag/BT nanocomplex compacts in Ba(OH)2 aqueous solution under the hydrothermal condition at 160 °C. The effective dielectric constant of the resultant Ag/BT nanocomplexes increases with an increase in Ag content. The maximal effective dielectric constant of approximately 900 was recorded for the nanocomplex with the Ag content of 10.7 vol %.

Effect of CeO₂ on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding.

PubMed

Chen, Tao; Liu, Defu; Wu, Fan; Wang, Haojun

2017-12-31

To solve the lack of wear resistance of titanium alloys for use in biological applications, various prepared coatings on titanium alloys are often used as wear-resistant materials. In this paper, TiC bioinert coatings were fabricated on Ti6Al4V by laser cladding using mixed TiC and ZrO₂ powders as the basic pre-placed materials. A certain amount of CeO₂ powder was also added to the pre-placed powders to further improve the properties of the TiC coatings. The effects of CeO₂ additive on the phase constituents, microstructures and wear resistance of the TiC coatings were researched in detail. Although the effect of CeO₂ on the phase constituents of the coatings was slight, it had a significant effect on the microstructure and wear resistance of the coatings. The crystalline grains in the TiC coatings, observed by a scanning electron microscope (SEM), were refined due to the effect of the CeO₂. With the increase of CeO₂ additive content in the pre-placed powders, finer and more compact dendrites led to improvement of the micro-hardness and wear resistance of the TiC coatings. Also, 5 wt % content of CeO₂ additive in the pre-placed powders was the best choice for improving the wear properties of the TiC coatings.

Strong composition-dependent variation of MCs + calibration factors in TiO x and GeO x ( x ≤ 2) films

NASA Astrophysics Data System (ADS)

Gnaser, Hubert; Le, Yongkang; Su, Weifeng

2006-07-01

The emission of MCs + secondary ions (M designates the analyte species) from TiO x (0.2 ≤ x ≤ 2) and GeO x (0.001 ≤ x ≤ 0.8) films under Cs + bombardment was examined. The relative calibration factors of OCs +/TiCs + and OCs +/GeCs + were determined and were found to depend pronouncedly on the O/Ti and O/Ge atomic concentration ratios. Specifically, with increasing oxygen content OCs + ions form much more efficiently (as compared to TiCs + or GeCs + ions), an enhancement amounting to more than a factor of 10 for the highest oxygen concentrations. Concurrently, the formation of TiOCs + or GeOCs + ions increases drastically. For both oxide systems, an empirical relation for the oxygen-concentration dependence of the relative calibration factors could be established.

Effect of hydrogen on the mechanical properties of titanium and its alloys

NASA Technical Reports Server (NTRS)

Beck, F. H.

1975-01-01

Occluded hydrogen resulting from cathodic charging of commercially pure titanium and titanium alloys, Ti-8Al-1Mo-1V and Ti-6Al-4V, was shown to cause embrittlement of the alloys. Embrittlement was a function of the interstitial hydrogen content rather than the amount of precipitated titanium hydride. The effects of hydrogen concentration on the critical strain for plastic instability along pure shear directions was determined for alloys Ti-8Al-1Mo-1V and Ti-5Al-2.5Sn. Hydrogen, in concentrations below that necessary for spontaneous hydride precipitation, increased the strain necessary for instability formation or instability failure. The strain rate sensitivity also increased with increasing hydrogen concentration. The effect of hydrogen on slip and twinning was determined for titanium single crystals. The critical resolved shear stress for prism slip was increased and the critical resolved shear stress for twinning was decreased with increasing hydrogen concentration.

Tribocorrosion behavior of beta titanium biomedical alloys in phosphate buffer saline solution.

PubMed

Pina, V Guiñón; Dalmau, A; Devesa, F; Amigó, V; Muñoz, A Igual

2015-06-01

The tribo-electrochemical behavior of different β titanium alloys for biomedical applications sintered by powder metallurgy has been investigated. Different mechanical, electrochemical and optical techniques were used to study the influence of the chemical composition, Sn content, and the electrochemical conditions on the tribocorrosion behavior of those alloys Ti30NbxSn alloys (where "x" is the weight percentage of Sn content, 2% and 4%). Sn content increases the active and passive dissolution rate of the titanium alloys, thus increasing the mechanically activated corrosion under tribocorrosion conditions. It also increases the mechanical wear of the alloy. Prevailing electrochemical conditions between -1 and 2V influences the wear accelerated corrosion by increasing it with the applied potential and slightly increases the mechanical wear of Ti30Nb4Sn. Wear accelerated corrosion can be predicted by existing models as a function of electrochemical and mechanical parameters of the titanium alloys. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect and mechanism of TiO2 nanoparticles on the photosynthesis of Chlorella pyrenoidosa.

PubMed

Middepogu, Ayyaraju; Hou, Jie; Gao, Xuan; Lin, Daohui

2018-06-14

Titanium dioxide nanoparticles (n-TiO 2 ) have been used in numerous applications, which results in their release into aquatic ecosystems and impact algal populations. A possible toxic mechanism of n-TiO 2 on algae is via the disruption of the photosynthetic biochemical pathways, which yet remains to be demonstrated. In this study, Chlorella pyrenoidosa was exposed to different concentrations (0, 0.1, 1, 5, 10, and 20 mg/L) of a type of anatase n-TiO 2 , and the physiological, biochemical, and molecular responses involved in photosynthesis were investigated. The 96 h half growth inhibition concentration (IC 50 ) of the n-TiO 2 to algae was determined to be 9.1 mg/L. A variety of cellular and sub-cellular damages were observed, especially the blurry lamellar structure of thylakoids, indicating the n-TiO 2 impaired the photosynthetic function of chloroplasts. Malondialdehyde (MDA) and glutathione disulfide (GSSG) significantly increased while the glutathione (GSH) content decreased. This implies the increased consumption of GSH by the increased intracellular oxidative stress upon n-TiO 2 was insufficient to eliminate the lipid peroxidation. The contents of photosynthetic pigments, including chlorophyll a (Chl a) and phycobiliproteins (PBPs) in the exposed algal cells increased along with the up-regulation of genes encoding Chl a and photosystem II (PS II), which could be explained by a compensatory effect to overcome the toxicity induced by the n-TiO 2 . On the other hand, the photosynthetic activity was significantly inhibited, indicating the impairment on the photosynthesis via damaging the reaction center of PS II. In addition, lower productions of adenosine triphosphate (ATP) and glucose, together with the change of gene expressions suggested that the n-TiO 2 disrupted the material and energy metabolisms in the photosynthesis. These findings support a paradigm shift of the toxic mechanism of n-TiO 2 from physical and oxidative damages to metabolic disturbances, and emphasize the threat to the photosynthesis of algae in contaminated areas. Copyright © 2018 Elsevier Inc. All rights reserved.

Nano-sculptured Janus-like TiAg thin films obliquely deposited by GLAD co-sputtering for temperature sensing.

PubMed

Pedrosa, Paulo; Ferreira, Armando; Martin, Nicolas; Arab Pour Yazdi, Mohammad; Billard, Alain; Lanceros-Mendez, Senentxu; Vaz, Filipe

2018-06-11

Inclined, zigzag and spiral TiAg films were prepared by GLancing Angle Deposition (GLAD), using two distinct Ti and Ag targets with a particle incident angle of 80º and Ag contents ranging from 20 to 75 at. %. The effect of increasing Ag incorporation and columnar architecture change on the morphological, structural and electrical properties of the films was investigated. It is shown that inclined columnar features (β = 47º) with high porosity were obtained for 20 at. % Ag, with the column angle sharply decreasing (β = 21º) for 50 at. % Ag, and steeply increasing afterwards until 37º for the film with 75 at. % Ag. The sputtered films exhibit a rather well-crystallized structure for Ag contents ≥ 50 at. %, with a TiAg (111) preferential growth. No significant oxidation was detected in all films, except for the one with 20 at. % Ag, after two 298-473-298 K temperature cycles in air. The calculated temperature coefficient of resistivity (TCR) values vary between 1.4 and 5.5×10-4 K-1. Nano-sculptured spiral films exhibit consistently higher resistivity (ρ = 1.5×10-6 Ω m) and TCR values (2.9×10-4 K-1) than the inclined one with the same Ag content (ρ = 1.2×10-6 Ω m and TCR = 2.0×10-4 K-1). No significant changes are observed in the zigzag films concerning these properties. The effective anisotropy Aeff at 473 K changes from 1.3 to 1.7 for the inclined films. Spiral films exhibit an almost completely isotropic behavior with Aeff = 1.1. Ag-rich TiAg core + shell Janus-like columns were obtained with increasing Ag concentrations. © 2018 IOP Publishing Ltd.

The effect of aluminium on the creep behavior of titanium aluminide alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nandy, T.K.; Mishra, R.S.; Gogia, A.K.

Small increases in the Al content of Ti{sub 3}Al-Nb alloys are known to improve creep resistance at the expense of the room temperature ductility. Though considerable work has been done on the creep behavior of titanium aluminide alloys, a systematic investigation involving the role of Al on the creep of aluminides is lacking. In the present study the authors have therefore carried out a complete investigation on stress and temperature effects on two alloys with differing Al contents, Ti-24Al-15Nb and Ti-26Al-15Nb (nominal composition in at%) in order to understand the effect of Al in terms of power law creep behavior.more » The following conclusions are made: (1) A strong Al effect on the creep resistance of O phase alloys in the Ti-Al-Nb systems has been confirmed, through a study of stress and temperature effects on the creep behavior of the Ti-24Al-15Nb and the Ti-26Al-15Nb compositions. (2) It has been shown, however, that the small differences in Al do not affect either the activation energies for creep ({approximately}370 kJ/mole) or the creep mechanism (climb controlled creep with a stress exponent of 4). The activation energies and stress exponents are similar to that observed in single phase O alloys. (3) It is suggested that Al influences creep strength through an intrinsic effect on the pre-exponential term AD{sub o} in the power law creep equation. It is possible that this effect is related to a higher ordering energy of the O phase with increasing Al content.« less

Preparation of Si and O co-solution strengthened Ti alloys by using rice husks as SiO2 resource and quantitative descriptions on their strengthening effects

NASA Astrophysics Data System (ADS)

Jia, Lei; Chen, Jiang-xian; Lu, Zhen-lin; Li, Shu-feng; Umeda, Junko; Kondoh, Katsuyoshi

2018-04-01

Ti alloys strengthened by both Si and O solutes were prepared by powder metallurgy method from pure Ti and amorphous SiO2 powder obtained by combusting rice husks. At the same time, Ti alloys singly strengthened by Si or O were also prepared for studying the strengthening effect of Si and O solutes. Results showed that amorphous SiO2 powder originated from rice husks could almost fully dissolve into pure Ti matrix when the content was not higher than 1.0 wt%, while higher content of SiO2 addition resulted in the formation of Ti5Si3 intermetallics. Si and O elements leaded to negative and positive distortion of Ti lattice, and the influencing degrees were ‑0.02 and +0.014 Å/wt% for lattice constant a, while ‑0.05 and +0.046 Å/wt% for constant c, respectively. Solid solution of Si and O would also result in the increase of hardness, which was 98.5 and 209.43 HV/wt%, respectively. When Si and O were co-exsited in Ti matrix, the negative and positive distortion cancelled each other, while the strengthening effect did not cancel but enhance each other.

Self-Organized TiO₂-MnO₂ Nanotube Arrays for Efficient Photocatalytic Degradation of Toluene.

PubMed

Nevárez-Martínez, María C; Kobylański, Marek P; Mazierski, Paweł; Wółkiewicz, Jolanta; Trykowski, Grzegorz; Malankowska, Anna; Kozak, Magda; Espinoza-Montero, Patricio J; Zaleska-Medynska, Adriana

2017-03-31

Vertically oriented, self-organized TiO₂-MnO₂ nanotube arrays were successfully obtained by one-step anodic oxidation of Ti-Mn alloys in an ethylene glycol-based electrolyte. The as-prepared samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis absorption, photoluminescence spectroscopy, X-ray diffraction (XRD), and micro-Raman spectroscopy. The effect of the applied potential (30-50 V), manganese content in the alloy (5-15 wt. %) and water content in the electrolyte (2-10 vol. %) on the morphology and photocatalytic properties was investigated for the first time. The photoactivity was assessed in the toluene removal reaction under visible light, using low-powered LEDs as an irradiation source (λ max = 465 nm). Morphology analysis showed that samples consisted of auto-aligned nanotubes over the surface of the alloy, their dimensions were: diameter = 76-118 nm, length = 1.0-3.4 μm and wall thickness = 8-11 nm. It was found that the increase in the applied potential led to increase the dimensions while the increase in the content of manganese in the alloy brought to shorter nanotubes. Notably, all samples were photoactive under the influence of visible light and the highest degradation achieved after 60 min of irradiation was 43%. The excitation mechanism of TiO₂-MnO₂ NTs under visible light was presented, pointing out the importance of MnO₂ species for the generation of e - and h⁺.

Correlation between electrical direct current resistivity and plasmonic properties of CMOS compatible titanium nitride thin films.

PubMed

Viarbitskaya, S; Arocas, J; Heintz, O; Colas-Des-Francs, G; Rusakov, D; Koch, U; Leuthold, J; Markey, L; Dereux, A; Weeber, J-C

2018-04-16

Damping distances of surface plasmon polariton modes sustained by different thin titanium nitride (TiN) films are measured at the telecom wavelength of 1.55 μm. The damping distances are correlated to the electrical direct current resistivity of the films sustaining the surface plasmon modes. It is found that TiN/Air surface plasmon mode damping distances drop non-linearly from 40 to 16μm as the resistivity of the layers increases from 28 to 130μΩ.cm, respectively. The relevance of the direct current (dc) electrical resistivity for the characterization of TiN plasmonic properties is investigated in the framework of the Drude model, on the basis of parameters extracted from spectroscopic ellipsometry experiments. By probing a parametric space of realistic values for parameters of the Drude model, we obtain a nearly univocal dependence of the surface plasmon damping distance on the dc resistivity demonstrating the relevance of dc resistivity for the evaluation of the plasmonic performances of TiN at telecom frequencies. Finally, we show that better plasmonic performances are obtained for TiN films featuring a low content of oxygen. For low oxygen content and corresponding low resistivity, we attribute the increase of the surface plasmon damping distances to a lower confinement of the plasmon field into the metal and not to a decrease of the absorption of TiN.

Raman spectroscopy of titanomagnetites: Calibration of the intensity of Raman peaks as a sensitive indicator for their Ti content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinin, Pavel; Tatsumi-Petrochilos, Lisa; Bonal, Lydie

2015-10-15

A systematic study of the Raman spectra of the titanomagnetite solid-solution series (Fe{sub 3-x}Ti{sub x}O{sub 4}) for x = {approx}0.0, 0.2, 0.4, and 0.6 has been conducted. The samples showed combinations of five previously predicted Raman peaks at {approx}190, 310, 460, 540, and 670 cm{sup -1} that correspond to vibrational modes with T{sub 2g}(1), E{sub g}, T{sub 2g}(3), T{sub 2g}(2), and A{sub 1g}, respectively. The calibration of Raman spectra for titanomagnetite with known values of Ti concentrations reveals a strong dependence of relative intensity for the T{sub 2g}(2) and T{sub 2g}(3) modes on Ti concentration. The most prominent feature ismore » the appearance and increase in the relative intensity of a T{sub 2g}(3) peak above x = {approx}0.2. On the other hand, the Raman peak for the T{sub 2g}(2) mode gradually diminishes as Ti increases and nearly disappears at x = {approx}0.6. Combining the two relative intensities potentially provides a sensitive indicator of Ti content. The technique was applied to study titanomagnetite in grains from Hana Volcanics and melatroctolite from Rhode Island.« less

Effects of TiO2 nanoparticles on the aquatic plant Spirodela polyrrhiza: Evaluation of growth parameters, pigment contents and antioxidant enzyme activities.

PubMed

Movafeghi, Ali; Khataee, Alireza; Abedi, Mahboubeh; Tarrahi, Roshanak; Dadpour, Mohammadreza; Vafaei, Fatemeh

2018-02-01

Plants are essential components of all ecosystems and play a critical role in environmental fate of nanoparticles. However, the toxicological impacts of nanoparticles on plants are not well documented. Titanium dioxide nanoparticles (TiO 2 -NPs) are produced worldwide in large quantities for a wide range of purposes. In the present study, the uptake of TiO 2 -NPs by the aquatic plant Spirodela polyrrhiza and the consequent effects on the plant were evaluated. Initially, structural and morphological characteristics of the used TiO 2 -NPs were determined using XRD, SEM, TEM and BET techniques. As a result, an anatase structure with the average crystalline size of 8nm was confirmed for the synthesized TiO 2 -NPs. Subsequently, entrance of TiO 2 -NP S to plant roots was verified by fluorescence microscopic images. Activity of a number of antioxidant enzymes, as well as, changes in growth parameters and photosynthetic pigment contents as physiological indices were assessed to investigate the effects of TiO 2 -NPs on S. polyrrhiza. The increasing concentration of TiO 2 -NPs led to the significant decrease in all of the growth parameters and changes in antioxidant enzyme activities. The activity of superoxide dismutase enhanced significantly by the increasing concentration of TiO 2 -NPs. Enhancement of superoxide dismutase activity could be explained as promoting antioxidant system to scavenging the reactive oxygen species. In contrast, the activity of peroxidase was notably decreased in the treated plants. Reduced peroxidase activity could be attributed to either direct effect of these particles on the molecular structure of the enzyme or plant defense system damage due to reactive oxygen species. Copyright © 2017. Published by Elsevier B.V.

Efficient photodecomposition of herbicide imazapyr over mesoporous Ga2O3-TiO2 nanocomposites.

PubMed

Ismail, Adel A; Abdelfattah, Ibrahim; Faisal, M; Helal, Ahmed

2018-01-15

The unabated release of herbicide imazapyr into the soil and groundwater led to crop destruction and several pollution-related concerns. In this contribution, heterogeneous photocatalytic technique was employed utilizing mesoporous Ga 2 O 3 -TiO 2 nanocomposites for degrading imazapyr herbicide as a model pollutant molecule. Mesoporous Ga 2 O 3 -TiO 2 nanocomposites with varied Ga 2 O 3 contents (0-5wt%) were synthesized through sol-gel process. XRD and Raman spectra exhibited extremely crystalline anatase TiO 2 phase at low Ga 2 O 3 content which gradually reduced with the increase of Ga 2 O 3 content. TEM images display uniform TiO 2 particles (10±2nm) with mesoporous structure. The mesoporous TiO 2 exhibits large surface areas of 167m 2 g -1 , diminished to 108m 2 g -1 upon 5% Ga 2 O 3 incorporation, with tunable mesopore diameter in the range of 3-9nm. The photocatalytic efficiency of synthesized Ga 2 O 3 -TiO 2 nanocomposites was assessed by degrading imazapyr herbicide and comparing with commercial photocatalyst UV-100 and mesoporous Ga 2 O 3 under UV illumination. 0.1% Ga 2 O 3 -TiO 2 nanocomposite is considered the optimum photocatalyst, which degrades 98% of imazapyr herbicide within 180min. Also, the photodegradation rate of imazapyr using 0.1% Ga 2 O 3 -TiO 2 nanocomposite is nearly 10 and 3-fold higher than that of mesoporous Ga 2 O 3 and UV-100, respectively. The high photonic efficiency and long-term stability of the mesoporous Ga 2 O 3 -TiO 2 nanocomposites are ascribed to its stronger oxidative capability in comparison with either mesoporous TiO 2 , Ga 2 O 3 or commercial UV-100. Copyright © 2017 Elsevier B.V. All rights reserved.

The regulation of TiO2 nanoparticles on the expression of light-harvesting complex II and photosynthesis of chloroplasts of Arabidopsis thaliana.

PubMed

Ze, Yuguan; Liu, Chao; Wang, Ling; Hong, Mengmeng; Hong, Fashui

2011-11-01

Recent studies demonstrated that titanium dioxide nanoparticles (TiO2 NPs) could significantly promote photosynthesis and plant growth, but its mechanism is still unclear. In this article, we studied the mechanism of light absorption and transfer of chloroplasts of Arabidopsis thaliana caused by TiO2 NPs treated. The results showed that TiO2 NPs could induce significant increases of light-harvesting complex II (LHCII) b gene expression and LHCII II content on the thylakoid membrane in A. thaliana, and the increases in LHCII were higher than the non-nano TiO2 (bulk-TiO2) treatment. Meanwhile, spectroscopy assays indicated that TiO2 NPs obviously increased the absorption peak intensity of the chloroplast in red and blue region, the fluorescence quantum yield near 680 nm, the excitation peak intensity near 440 and 480 nm and/or near 650 and 680 nm of the chloroplast. TiO2 NPs treatment could reduce F480/F440 ratio and increase F650/F680 ratio and accelerate the rate of whole chain electron transport and oxygen evolution of the chloroplast. However, the photosynthesis improvement of the non-nanoTiO2 treatment was far less effective than TiO2 NPs treatment. Taken together, TiO2 NPs could promote the light absorption of chloroplast, regulate the distribution of light energy from PS I to PS II by increasing LHCII and accelerate the transformation from light energy to electronic energy, water photolysis, and oxygen evolution.

Toxicity of TiO2 Nanoparticles to Escherichia coli: Effects of Particle Size, Crystal Phase and Water Chemistry

PubMed Central

Lin, Xiuchun; Li, Jingyi; Ma, Si; Liu, Gesheng; Yang, Kun; Tong, Meiping; Lin, Daohui

2014-01-01

Controversial and inconsistent results on the eco-toxicity of TiO2 nanoparticles (NPs) are commonly found in recorded studies and more experimental works are therefore warranted to elucidate the nanotoxicity and its underlying precise mechanisms. Toxicities of five types of TiO2 NPs with different particle sizes (10∼50 nm) and crystal phases were investigated using Escherichia coli as a test organism. The effect of water chemistry on the nanotoxicity was also examined. The antibacterial effects of TiO2 NPs as revealed by dose-effect experiments decreased with increasing particle size and rutile content of the TiO2 NPs. More bacteria could survive at higher solution pH (5.0–10.0) and ionic strength (50–200 mg L−1 NaCl) as affected by the anatase TiO2 NPs. The TiO2 NPs with anatase crystal structure and smaller particle size produced higher content of intracellular reactive oxygen species and malondialdehyde, in line with their greater antibacterial effect. Transmission electron microscopic observations showed the concentration buildup of the anatase TiO2 NPs especially those with smaller particle sizes on the cell surfaces, leading to membrane damage and internalization. These research results will shed new light on the understanding of ecological effects of TiO2 NPs. PMID:25310452

Microstructural Characterization of Melt Extracted High-Nb-Containing TiAl-Based Fiber

PubMed Central

Zhang, Shuzhi; Zhang, Shuling; Chen, Yanfei; Han, Jianchao; Zhang, Changjiang; Wang, Xiaopeng; Chen, Yuyong

2017-01-01

The microstructure of melt extracted Ti-44Al-8Nb-0.2W-0.2B-1.5Si fiber were investigated. When the rotation speed increased from 2000 to 2600 r/min, the appearance of the wire was uniform with no Rayleigh-wave default. The structure was mainly composed of fine α2 (α) phase dendritic crystal and a second phase between dendrite arms and grain boundaries. The precipitated second phases were confirmed to be Ti5Si3 from the eutectic reaction L→Ti5Si3 + α and TiB. As the lower content of Si and higher cooling rate, a divorced eutectic microstructure was obtained. Segregation of Ti, Nb, B, Si, and Al occurred during rapid solidification. PMID:28772555

Effect of Pb content and solution concentration of Pb{sub x}TiO{sub 3} seed layer on (100)-texture and ferroelectric/dielectric behavior of PZT (52/48) thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Jian; Batra, Vaishali; Han, Hui

The effect of Pb content and solution concentration of lead titanate (Pb{sub x}TiO{sub 3}) seed layer on the texture and electric properties of Pb{sub 1.1}(Zr{sub 0.52},Ti{sub 0.48})O{sub 3} (PZT) thin films was investigated. A variety of seed layers (y Pb{sub x}TiO{sub 3}) with varying solution concentration (y = 0.02, 0.05, 0.1, and 0.2 M) and Pb content (x = 1.0, 1.05, 1.1, and 1.2) was deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates using chemical-solution deposition method. PZT films were then deposited on these seed layers using the same process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy investigations of the seed layers confirm change in crystal structuremore » with variation in the solution properties. XRD studies of PZT films deposited on seed layers demonstrate that the seed layer helps in enhancing (100)-texture and suppressing (111)-texture. It was observed that PZT films prepared on seed layers with lower solution concentrations results in highly (100)-textured films, which further helps to improve the electric properties. The polarization and dielectric constant of the PZT films were seen to increase while the coercive field decreased with increase in (100)-texture. Irrespective of the seed layer solution concentration, higher Pb content in the seed layer deteriorates the PZT film properties. Ninety-five percent to ninety-six percent (100)-texture was obtained from thin PZT films deposited on seed layers of 0.02 M solution concentration with 1.05 and 1.10 Pb contents, which is higher than the values reported for thick PZT films. Optimization of both Pb content and solution concentration of the seed layer is a promising route to achieve highly (100)-textured PZT films with improved electric properties.« less

Photoinduced Glycerol Oxidation over Plasmonic Au and AuM (M = Pt, Pd and Bi) Nanoparticle-Decorated TiO2 Photocatalysts

PubMed Central

Jedsukontorn, Trin; Saito, Nagahiro; Hunsom, Mali

2018-01-01

In this study, sol-immobilization was used to prepare gold nanoparticle (Au NP)-decorated titanium dioxide (TiO2) photocatalysts at different Au weight % (wt. %) loading (Aux/TiO2, where x is the Au wt. %) and Au–M NP-decorated TiO2 photocatalysts (Au3M3/TiO2), where M is bismuth (Bi), platinum (Pt) or palladium (Pd) at 3 wt. %. The Aux/TiO2 photocatalysts exhibited a stronger visible light absorption than the parent TiO2 due to the localized surface plasmon resonance effect. Increasing the Au content from 1 wt. % to 7 wt. % led to increased visible light absorption due to the increasing presence of defective structures that were capable of enhancing the photocatalytic activity of the as-prepared catalyst. The addition of Pt and Pd coupled with the Au3/TiO2 to form Au3M3/TiO2 improved the photocatalytic activity of the Au3/TiO2 photocatalyst by maximizing their light-absorption property. The Au3/TiO2, Au3Pt3/TiO2 and Au3Pd3/TiO2 photocatalysts promoted the formation of glyceraldehyde from glycerol as the principle product, while Au3Bi3/TiO2 facilitated glycolaldehyde formation as the major product. Among all the prepared photocatalysts, Au3Pd3/TiO2 exhibited the highest photocatalytic activity with a 98.75% glycerol conversion at 24 h of reaction time. PMID:29690645

Solvothermal fabrication of TiO2/sepiolite composite gel with exposed {0 0 1} and {1 0 1} facets and its enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Liu, Ruirui; Ji, Zhijiang; Wang, Jing; Zhang, Jinjun

2018-05-01

A novel TiO2/sepiolite composite gel (TiSG) was fabricated in the presence of cetyltrimethylammonium bromide (CTAB) through a simple solvothermal reaction in an acetic acid-water solvent. A homogeneous anchoring of TiO2 nanoparticles with exposed {0 0 1} and {1 0 1} facets on sepiolite nanofibers was achieved. CTAB content, solvothermal temperature/time, and HAc content play crucial roles in the morphological and facet formation of TiSG. A possible mechanism for the formation of TiSG was further proposed. CTAB as capping/shape-controlling agent can strongly bind to the more reactive (0 0 1) facet of TiO2 and then mitigate the thermodynamically favored (0 0 1) plane growth. Eventually, the truncated octahedral TiO2 was obtained by controlling the growth rates in 〈0 0 1〉 and 〈1 0 1〉 directions. Sepiolite as a cross-linking agent provides sufficient crosslinking sites for TiO2 to induce three-dimensional (3D) network formation, thereby generating the composite gel. The synthesized TiSG samples were then used as photocatalysts, which exhibited increased methyl orange removal under UV-vis light (350-780 nm) by the synergistic effect of adsorption and in-situ photocatalytic degradation as compared to P25 and bare TiO2. The excellent photocatalytic performance of TiSG was mainly ascribed to the formations of 3D gel structure and surface heterojunctions between (0 0 1) and (1 0 1) facets.

Corrosive effects of fluoride on titanium: investigation by X-ray photoelectron spectroscopy, atomic force microscopy, and human epithelial cell culturing.

PubMed

Stájer, Anette; Ungvári, Krisztina; Pelsoczi, István K; Polyánka, Hilda; Oszkó, Albert; Mihalik, Erzsébet; Rakonczay, Zoltán; Radnai, Márta; Kemény, Lajos; Fazekas, András; Turzó, Kinga

2008-11-01

High fluoride (F(-)) concentrations and acidic pH impair the corrosion resistance of titanium (Ti). Effects of F(-)-containing caries-preventive prophylactic rinses, and gels on Ti were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Human epithelial cell attachment and proliferation were investigated by dimethylthiazol-diphenyl tetrazolium bromide (MTT) and protein content assays. Aqueous 1% NaF solution (3800 ppm F(-), pH 4.5) or high (12,500 ppm) F(-) content gel (pH 4.8) strongly corroded the surface and modified its composition. XPS revealed formation of a strongly bound F(-)-containing complex (Na(2)TiF(6)). AFM indicated an increase in roughness (R(a)) of the surfaces: 10-fold for the NaF solution and smaller for the gel or a mouthwash (250 ppm F(-), pH 4.4). MTT revealed that cell attachment was significantly increased by the gel, but was not disturbed by either the mouthwash or the NaF. Cell proliferation determined by MTT decreased significantly only for the NaF-treated samples; protein content assay experiments showed no such effect. This study indicates that epithelial cell culturing results can depend on the method used, and the adverse effects of a high F(-) concentration and low pH should be considered when prophylactic gels are applied by patients with Ti implants or other dental devices.

Polymorphic Transitions in Cerium-Substituted Zirconolite (CaZrTi 2O 7)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Braeden M.; Sundaram, S. K.; Misture, Scott T.

Compounds with the formulae CaZr 1–xCe xTi 2O 7 with x = 0.1–0.5 were synthesized by solid state reaction. Cerium was used as a surrogate for actinide elements. A transition from the 2M polymorph to the 4M polymorph (expanded unit cell due to cation ordering) in zirconolite was observed with increasing cerium content. The presence of both tri- and tetravalent Ce, contrary to formulation, was confirmed using X-ray absorption near edge spectroscopy, suggesting substitution on both Ca and Zr sites. Sintering was carried out via spark plasma sintering, during which the perovskite phase (Ca 0.4Ce 0.4TiO 3) was stabilized duemore » to the reducing conditions of this technique. Scanning electron microscopy and energy dispersive spectrometry revealed that the 2M polymorph was dilute in Ce content in comparison to the 4M-zirconolite. High temperature X-ray diffraction was used to detail the kinetics of perovskite to zirconolite transition. It was found that CaCeTi 2O 7 (cubic pyrochlore) formed as an intermediate phase during the transition. Lastly, our results show that a transition from 2M- to 4M-zirconolite occurs with increasing Ce content and can be controlled by adjusting the P O2 and the heat treatment temperature.« less

Polymorphic Transitions in Cerium-Substituted Zirconolite (CaZrTi 2O 7)

DOE PAGES

Clark, Braeden M.; Sundaram, S. K.; Misture, Scott T.

2017-07-19

Compounds with the formulae CaZr 1–xCe xTi 2O 7 with x = 0.1–0.5 were synthesized by solid state reaction. Cerium was used as a surrogate for actinide elements. A transition from the 2M polymorph to the 4M polymorph (expanded unit cell due to cation ordering) in zirconolite was observed with increasing cerium content. The presence of both tri- and tetravalent Ce, contrary to formulation, was confirmed using X-ray absorption near edge spectroscopy, suggesting substitution on both Ca and Zr sites. Sintering was carried out via spark plasma sintering, during which the perovskite phase (Ca 0.4Ce 0.4TiO 3) was stabilized duemore » to the reducing conditions of this technique. Scanning electron microscopy and energy dispersive spectrometry revealed that the 2M polymorph was dilute in Ce content in comparison to the 4M-zirconolite. High temperature X-ray diffraction was used to detail the kinetics of perovskite to zirconolite transition. It was found that CaCeTi 2O 7 (cubic pyrochlore) formed as an intermediate phase during the transition. Lastly, our results show that a transition from 2M- to 4M-zirconolite occurs with increasing Ce content and can be controlled by adjusting the P O2 and the heat treatment temperature.« less

Relating Chemical and Topographical Modification of Materials to Macroscopic Adhesion

DTIC Science & Technology

2011-11-14

CFRP, T800H/3900-2) and titanium alloy (Ti- 6Al - 4V ) surfaces are presented, before and after surface treatment, using a number of surface...Experimental: Titanium alloy (Ti- 6Al - 4V , an alloy consisting of 90% titanium , 6% aluminum and 4% vanadium, 0.063" thick) was purchased from...spectrum indicates a dramatic decrease in oxygen content and a concomitant increase in titanium metal alloy (Ti- 6Al - 4V ) at the surface. This

Effect of CeO2 on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding

PubMed Central

Wang, Haojun

2017-01-01

To solve the lack of wear resistance of titanium alloys for use in biological applications, various prepared coatings on titanium alloys are often used as wear-resistant materials. In this paper, TiC bioinert coatings were fabricated on Ti6Al4V by laser cladding using mixed TiC and ZrO2 powders as the basic pre-placed materials. A certain amount of CeO2 powder was also added to the pre-placed powders to further improve the properties of the TiC coatings. The effects of CeO2 additive on the phase constituents, microstructures and wear resistance of the TiC coatings were researched in detail. Although the effect of CeO2 on the phase constituents of the coatings was slight, it had a significant effect on the microstructure and wear resistance of the coatings. The crystalline grains in the TiC coatings, observed by a scanning electron microscope (SEM), were refined due to the effect of the CeO2. With the increase of CeO2 additive content in the pre-placed powders, finer and more compact dendrites led to improvement of the micro-hardness and wear resistance of the TiC coatings. Also, 5 wt % content of CeO2 additive in the pre-placed powders was the best choice for improving the wear properties of the TiC coatings. PMID:29301218

Effects of Fabrication Parameters on Interface of Zirconia and Ti-6Al-4V Joints Using Zr55Cu30Al10Ni5 Amorphous Filler

NASA Astrophysics Data System (ADS)

Liu, Yuhua; Hu, Jiandong; Shen, Ping; Guo, Zuoxing; Liu, Huijie

2013-09-01

ZrO2 was brazed to Ti-6Al-4V using a Zr55Cu30Al10Ni5 (at.%) amorphous filler in a high vacuum at 1173-1273 K. The influences of brazing temperature, holding time, and cooling rate on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be characterized as ZrO2/ZrO2- x + TiO/(Zr,Ti)2(Cu,Ni)/(Zr,Ti)2(Cu,Ni,Al)/acicular Widmanstäten structure/Ti-6Al-4V. With the increase in the brazing temperature, both the thickness of the ZrO2- x + TiO layer and the content of the (Zr,Ti)2(Cu,Ni) phase decreased. However, the acicular Widmanstäten structure gradually increased. With the increase in the holding time, the (Zr,Ti)2(Cu,Ni) phase decreased, and the thickness of the (Zr,Ti)2(Cu,Ni) + (Zr,Ti)2(Cu,Ni,Al) layer decreased. In addition, cracks formed adjacent to the ZrO2 side under rapid cooling. The microstructures produced under various fabrication parameters directly influence the shear strength of the joints. When ZrO2 and Ti-6Al-4V couples were brazed at 1173 K for 10 min and then cooled at a rate of 5 K/min, the maximum shear strength of 95 MPa was obtained.

Sol-gel preparation of self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective coating for solar glass

NASA Astrophysics Data System (ADS)

Lin, Wensheng; Zheng, Jiaxian; Yan, Lianghong; Zhang, Xinxiang

2018-03-01

Self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective (AR) coating is prepared by sol-gel process. SiO2 sol is prepared by using tetraethyl orthosilicate (TEOS) as precursor and ammonia as catalyst, while TiO2 sol was prepared by using tetrabutyl orthotitanate (TBOT) as precursor and hydrochloric acid as catalyst. The effect of TiO2 content on refractive index, abrasion-resistance and photo-catalytic activity of SiO2-TiO2 hybrid thin films or powders is systematically investigated. It is found that the refractive index of SiO2-TiO2 hybrid thin films increases gradually from 1.18 to 1.53 as the weight ratio of TiO2 to SiO2 increased from 0 to 1.0. The SiO2-TiO2 hybrid thin film and powder possesses good abrasion-resistance and photo-catalytic activity, respectively, as the weight ratio of TiO2 to SiO2 is 0.4. The degradation degree of Rhodamine B by SiO2-TiO2 hybrid powder is 88.3%. Finally, SiO2-TiO2/SiO2-TiO2 double-layer AR coating with high transmittance, abrasion-resistance and self-cleaning property is realized.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moskowitz, D.; Humenik, M. Jr.

TiC--Ni--Mo--C compositions were prepared with binders containing 22.5 w/o Ni. The Mo content and the carbon content were varied. The amount of Ti in the binder phase was for determining the strength of the material, due to a solid solution strengthening; the optimum Ti content is a function of the amount of Mo additions.

Structure and Mechanical Properties of As-Cast Ti-5Sn-xMo Alloys.

PubMed

Yu, Hsing-Ning; Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang; Ho, Wen-Fu

2017-04-27

Ti-5Sn- x Mo ( x = 0, 1, 3, 5, 7.5, 10, 12.5, 15, 17.5, and 20 wt %) alloys were designed and prepared for application as implant materials with superior mechanical properties. The results demonstrated that the crystal structure and mechanical properties of Ti-5Sn- x Mo alloys are highly affected by their Mo content. The as-cast microstructures of Ti-5Sn- x Mo alloys transformed in the sequence of phases α' → α″ → β, and the morphologies of the alloys changed from a lath structure to an equiaxed structure as the Mo content increased. The α″-phase Ti-5Sn-7.5Mo (80 GPa) and β-phase Ti-5Sn-10Mo (85 GPa) exhibited relatively low elastic moduli and had excellent elastic recovery angles of 27.4° and 37.8°, respectively. Furthermore, they exhibited high ductility and moderate strength, as evaluated using the three-point bending test. Search for a more suitable implant material by this study, Ti-5Sn- x Mo alloys with 7.5 and 10 wt % Mo appear to be promising candidates because they demonstrate the optimal combined properties of microhardness, ductility, elastic modulus, and elastic recovery capability.

[Study on content of nickel in saliva released from the nickel-chromium and the nickel-chromium-titanium porcelain alloy].

PubMed

Wang, Wen-Jie; Zhang, Tai-Qiang; Wei, Hong

2010-02-01

The purpose of the study was to investigate the content of nickel (Ni) ion in patients' saliva after wearing the porcelain-fused-to nickel-chromium (Ni-Cr) crown or the porcelain-fused-to nickel-chromium-titanium(Ni-Cr-Ti) crown. 50 patients who had one molar or premolar needed repairing were selected and divided into two groups randomly. Patients in one group were fabricated with porcelain-fused-to Ni-Cr crown and the patients in the other group were fabricated with porcelain-fused-to Ni-Cr-Ti crown. Collect the patients' saliva before wearing, 1 week, 3 months, and 6 months after wearing. The content of Ni ion in saliva was detected by inductively coupled plasma mass spectrometry (ICP-MS). The content of Ni ion in both groups increased at the first week, and go back after 6 months. There were no significant differences before wearing, 1 week, 3 months, and 6 months after wearing. There were no significant differences between the two groups. Wearing the porcelain-fused-to Ni-Cr crown or the porcelain-fused-to Ni-Cr-Ti crown has no significant influence on the content of Ni ion in saliva.

Bimodal TiO2 Contents of Mare Basalts at Apollo and Luna Sites and Implications for TiO2 Derived from Clementine Spectral Reflectance

NASA Technical Reports Server (NTRS)

Gillis, J. J.; Jolliff, B. L.

2001-01-01

A revised algorithm to estimate Ti contents of mare regions centered on Apollo and Luna sites shows a bimodal distribution, consistent with mare-basalt sample data. A global TiO2 map shows abundant intermediate TiO2 basalts in western Procellarum. Additional information is contained in the original extended abstract.

Effects of TiN coating on the corrosion of nanostructured Ti-30Ta-xZr alloys for dental implants

NASA Astrophysics Data System (ADS)

Kim, Won-Gi; Choe, Han-Cheol

2012-01-01

Electrochemical characteristics of a titanium nitride (TiN)-coated/nanotube-formed Ti-Ta-Zr alloy for biomaterials have been researched by using the magnetic sputter and electrochemical methods. Ti-30Ta-xZr (x = 3, 7 and 15 wt%) alloys were prepared by arc melting and heat treated for 24 h at 1000 °C in an argon atmosphere and then water quenching. The formation of oxide nanotubes was achieved by anodizing a Ti-30Ta-xZr alloy in H3PO4 electrolytes containing small amounts of fluoride ions at room temperature. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. The microstructure and morphology of nanotube arrays were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The TiN coatings were obtained by the radio-frequency (RF) magnetron sputtering technique. The depositions were performed from pure Ti targets on Ti-30Ta-xZr alloys substrates. The corrosion properties of the specimens were examined using potentiodynamic test in a 0.9% NaCl solution by using potentiostat. The microstructures of Ti-30Ta-xZr alloys were changed from an equiaxed to a needle-like structure with increasing Zr content. The interspace between the nanotubes was approximately 20, 80 and 200 nm for Zr contents of 3, 7 and 15 wt%, respectively. The corrosion resistance of the TiN-coated on the anodized Ti-30Ta-xZr alloys was higher than that of the untreated Ti alloys, indicating a better protective effect.

Titanium Carbide Nanofibers-Reinforced Aluminum Compacts, a New Strategy to Enhance Mechanical Properties.

PubMed

Khalil, Khalil Abdelrazek; Sherif, El-Sayed M; Nabawy, A M; Abdo, Hany S; Marzouk, Wagih W; Alharbi, Hamad F

2016-05-20

TiC nanofibers reinforced Al matrix composites were produced by High Frequency Induction Heat Sintering (HFIHS).The titanium carbide nanofibers with an average diameter of 90 nm are first prepared by electrospinning technique and high temperature calcination process. A composite solution containing polyacrylonitrile and titanium isopropoxide is first electrospun into the nanofibers, which are subsequently stabilized and then calcined to produce the desired TiC nanofibers. The X-ray diffraction pattern and transmission electron microscopy results show that the main phase of the as-synthesized nanofibers is titanium carbide. The TiC nanofibers is then mixed with the aluminum powders and introduced into high frequency induction heat sintering (HFIHS) to produce composites of TiC nanofibers reinforced aluminum matrix. The potential application of the TiC nanofibers reinforced aluminum matrix composites was systematically investigated. 99.5% relative density and around 85 HV (833 MPa) Vickers hardness of the Al reinforced with 5 wt % TiC nanofiber has been obtained. Furthermore, the sample of Al contains 5 wt % TiC, has the highest value of compression and yield strength of about 415 and 350 MPa, respectively. The ductility of the Al/5 wt % TiC showed increasing with increasing the TiC contents.

Ti(Ni,Cu) pseudobinary compounds as efficient negative electrodes for Ni-MH batteries

NASA Astrophysics Data System (ADS)

Emami, Hoda; Cuevas, Fermin; Latroche, Michel

2014-11-01

The effect of Ni by Cu substitution on the structural, solid-gas and electrochemical hydrogenation properties of TiNi has been investigated. Pseudo-binary TiNi1-xCux (x ≤ 0.5) compounds have been synthesized by induction melting. They crystallize in B2 structure above 350 K and either in B19‧ (x < 0.1) or B19 (0.2 ≤ x ≤ 0.5) at room temperature (RT). For all compounds, Pressure-Composition Isotherms at 423 K exhibit a single slopping plateau pressure within the range 10-3-1 MPa of hydrogen pressure revealing a metal to hydride transformation. Both the hydrogenation capacity and the hydride stability decrease with Cu-content. The hydrided pseudobinary compounds crystallize in the tetragonal S.G. I4/mmm structure as for TiNi hydride. The electrochemical discharge capacity increases with Cu content from 150 mAh g-1 for TiNi up to 300 mAh g-1 for TiNi0.8Cu0.2 and then decreases again for larger Cu amounts. Electrochemical isotherms and in-situ neutron diffraction measurements at RT demonstrate that such a capacity increase results from a metal to hydride phase transformation in which the hydride phase is destabilized by Cu substitution. The TiNi0.8Cu0.2 compound exhibits interesting cycling stability for 30 cycles and good high-rate capability at D/2 rate. This compound has promising electrochemical properties as compared to commercial LaNi5-type alloys with the advantage of being rare-earth metal free.

Investigation of structure and mechanical properties of plasma vapor deposited nanocomposite TiBN films

NASA Astrophysics Data System (ADS)

Han, Bin; Neena, D.; Wang, Zesong; Kondamareddy, K. k.; Li, Na; Zuo, Wenbin; Yan, Shaojian; Liu, Chuansheng; Fu, Dejun

2017-04-01

TiBN coatings have huge potential applications as they have excellent properties with increasing modern industrial requirements. Nanocomposite TiBN coatings were synthesized on cemented carbide, high speed steel and Si substrates by using cathodic arc plasma ion plating from pure TiB2 ceramic targets. The structure and mechanical properties of the TiBN coatings were significantly influenced by the nitrogen partial pressure. Rutherford backscattering spectrometry demonstrates that the nitrogen content of the coating varied from 2.8% to 34.5% and high-resolution electron microscopy images reveal that all coatings have the characteristic of nanocrystals embedded in an amorphous matrix. The root-mean-square roughness of the coatings increases from 3.73 to 14.64 nm and the coefficients of friction of the coatings at room temperature vary from 0.54 to 0.73 with increasing nitrogen partial pressure. The microhardness of the coating increases up to 35.7 GPa at 10 sccm N2 flow rate. The smallest wear rate is 2.65 × 10-15 m3 N-1 m-1 which indicates that TiBN coatings have excellent wear resistance. The adhesion test revealed that the TiBN coatings have good adhesion at low nitrogen partial pressure.

Development and characterization of (Ti, Mo)C carbides reinforced Fe-based surface composite coating produced by laser cladding

NASA Astrophysics Data System (ADS)

Wang, Xinhong; Zhang, Min; Qu, Shiyao

2010-09-01

In this study, in situ multiple carbides reinforced Fe-based surface composite coatings were fabricated successfully by laser cladding a precursor mixture of graphite, ferrotitanium (Fe-Ti) and ferromolybdenum (Fe-Mo) powders. The results showed that (Ti, Mo)C particles with flower-like and cuboidal shapes were in situ formed during the solidification and most shapes of (Ti, Mo)C particles were diversiform according to different contents of Fe-Mo powder in the Fe-Ti-Mo-C system. The growth morphology of the reinforcing (Ti, Mo)C carbide has typically faceted features, indicating that the lateral growth mechanism is still predominant growth mode under rapid solidification conditions. Increasing the amount of Fe-Mo in the reactants led to a decrease of carbide size and an increase of volume fraction of carbides. The coatings had good cracking resistance when the amounts of Fe-Mo were controlled within a range of 15 wt%.

Preparation of porous nitrogen-doped titanium dioxide microspheres and a study of their photocatalytic, antibacterial and electrochemical activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, S.; Chu, W., E-mail: chuwei65@yahoo.com.cn; Huang, Y.Y.

Graphical abstract: Porous N-doped TiO{sub 2} microspheres were prepared for the first time via plasma technique. The sample exhibited better photocatalytic activity, photoinduced inactivation activity and better electrochemical activity than those of TiO{sub 2} microspheres and P25. Display Omitted Highlights: ► Porous N-doped TiO{sub 2} microspheres were prepared via nitrogen plasma technique. ► Plasma treatment did not affect the porous structure of the TiO{sub 2} microspheres. ► With the plasma treatment, the N contents in the samples increased. ► Their photocatalytic, antibacterial and electrochemical activities were studied. -- Abstract: Nitrogen-doped titanium dioxide (N-doped TiO{sub 2}) microspheres with porous structure weremore » prepared via the nitrogen-assisted glow discharge plasma technique at room temperature for the first time. The samples were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption–desorption measurement, UV–Vis diffuse reflectance spectra, photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The results indicated that the plasma treatment did not affect the porous structure of the TiO{sub 2} microspheres. With the plasma treatment, the N contents in the samples increased. During the photocatalytic degradation of methylene blue under simulative sunlight irradiation, the sample after plasma treatment for 60 min (N-TiO{sub 2}-60) exhibited higher photocatalytic activity than those of the TiO{sub 2} microspheres, P25 and other N-doped TiO{sub 2} microspheres. Furthermore, the N-TiO{sub 2}-60 showed excellent antibacterial activities towards Escherichia coli under visible irradiation. These should be attributed to the enhancement of the visible light region absorption for TiO{sub 2} after N-doping. Electrochemical data demonstrated that the N-doping not only enhanced the electrochemical activity of TiO{sub 2}, but also improved the reversibility of Li insertion/extraction reactions and the rate behavior of TiO{sub 2} during charge–discharge cycles.« less

A Comparison in Mechanical Properties of Cermets of Calcium Silicate with Ti-55Ni and Ti-6Al-4V Alloys for Hard Tissues Replacement

PubMed Central

Pramanik, Sumit; Shirazi, Seyed Farid Seyed; Mehrali, Mehdi; Yau, Yat-Huang; Abu Osman, Noor Azuan

2014-01-01

This study investigated the impact of calcium silicate (CS) content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%). The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young's modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements. PMID:25538954

The effect of Al segregation on Schottky barrier height and effective work function in TiAl/TiN/HfO2 gate stacks

NASA Astrophysics Data System (ADS)

Kim, Geun-Myeong; Oh, Young Jun; Chang, K. J.

2016-07-01

We perform first-principles density functional calculations to investigate the effects of Al incorporation on the p-type Schottky barrier height ≤ft({φ\\text{p}}\\right) and the effective work function for various high-k/metal gate stacks, such as TiN/HfO2 with interface Al impurities, Ti1-x Al x N/HfO2, and TiAl/TiN/HfO2. When Al atoms substitute for the interface Ti atoms at TiN/HfO2 interface, interface dipole fields become stronger, leading to the increase of {φ\\text{p}} and thereby the n-type shift of effective work function. In Ti1-x Al x N/HfO2 interface, {φ\\text{p}} linearly increases with the Al content, attributed to the presence of interface Al atoms. On the other hand, in TiAl/TiN/HfO2 interface, where Al is assumed not to segregate from TiAl to TiN, {φ\\text{p}} is nearly independent of the thickness of TiAl. Our results indicate that Al impurities at the metal/dielectric interface play an important role in controlling the effective work function, and provide a clue to understanding the n-type shift of the effective work function observed in TiAl/TiN/HfO2 gate stacks fabricated by using thegate-last process.

In-situ formation of Ni4Ti3 precipitate and its effect on pseudoelasticity in selective laser melting additive manufactured NiTi-based composites

NASA Astrophysics Data System (ADS)

Gu, Dongdong; Ma, Chenglong

2018-05-01

Selective laser melting (SLM) additive manufacturing technology was applied to synthesize NiTi-based composites via using ball-milled Ti, Ni, and TiC mixed powder. By transmission electron microscope (TEM) characterization, it indicated that the B2 (NiTi) matrix was obtained during SLM processing. In spite of more Ti content (the Ti/Ni ratio >1), a mass of Ni-rich intermetallic compounds containing Ni4Ti3 with nanostructure features and eutectic Ni3Ti around in-situ Ti6C3.75 dendrites were precipitated. Influence of the applied laser volume energy density (VED) on the morphology and content of Ni4Ti3 precipitate was investigated. Besides, nanoindentation test of the matrix was performed in order to assess pseudoelastic recovery behavior of SLM processed NiTi-based composites. At a relatively high VED of 533 J/mm3, the maximum pseudoelastic recovery was obtained due to the lowest content of Ni4Ti3 precipitates. Furthermore, the precipitation mechanism of in-situ Ni4Ti3 was present based on the redistribution of titanium element and thermodynamics analysis, and then the relationship of Ni4Ti3 precipitate, VED and pseudoelastic recovery behavior was also revealed.

Rapidly sintering of interconnected porous Ti-HA biocomposite with high strength and enhanced bioactivity.

PubMed

Zhang, L; He, Z Y; Zhang, Y Q; Jiang, Y H; Zhou, R

2016-10-01

In this work, interconnected porous Ti-HA biocomposites with enhanced bioactivity, high porosity and compressive strength were prepared by spark plasma sintering (SPS) and space holder method. Pore characteristics, mechanical properties, corrosion behaviors and in vitro bioactivity of the porous Ti-HA were investigated. Results showed that porous Ti-HA with 5-30wt% HA contents possessed not only low elastic modulus of 8.2-15.8GPa (close to that of human bone) but also high compressive strength (86-388MPa). Although the HA partially decomposed and formed secondary phases, the sintered porous Ti-HA can still be good bioactivity. The homogeneity and the thickness of apatite layer increased significantly with the increase of HA. But with the thickness of apatite layer increased, micro-cracks appeared on the surface of porous Ti-30%HA. A model was built to discuss the current distribution and sintering mechanism of HA on Ti matrix during SPS process. It indicated that the excessive addition of HA would deteriorate the sintering quality, thus decreasing the mechanical properties and corrosion resistance. However, the combination of interconnected pore characteristics, low elastic modulus, high compressive strength and enhanced bioactivity might make porous Ti-HA biocomposites prepared by SPS a promising candidate for hard tissue implants. Copyright © 2016 Elsevier B.V. All rights reserved.

An Investigation of Dielectric, Piezoelectric Properties and Microstructures of Bi0.5Na0.5TiO3-BaTiO3-Bi0.5K0.5TiO3 Lead-Free Piezoelectric Ceramics Doped with K2AlNbO5 Compound

NASA Astrophysics Data System (ADS)

Liu, Gang; Jiang, Wentao; Liu, Kaihua; Liu, Xiaokui; Song, Chunlin; Yan, Yan; Jin, Li

2017-08-01

The effect of K2AlNbO5 compound acting as both donor and accepter on the phase, microstructures and electrical properties of the 0.9362(Bi0.5Na0.5)TiO3-0.0637BaTiO3-0.02(Bi0.5K0.5)TiO3 [(1- x)(0.9163BNT-0.0637BT-0.02BKT)- x(K2AlNbO5)] (BNKBT-1000 xKAN) ternary lead-free piezoelectric ceramics was systematically investigated. When doping content of K2AlNbO5 was varied from 0 to 0.009, the BNKBT-1000 xKAN ceramics showed a single perovskite structure, and the phase structure transferred from a rhombohedral-tetragonal coexistent morphotropic phase boundaries zone to a tetragonal zone. The x-ray photoelectron spectroscopy analysis indicated that the chemical valence of the Nb and Al element are 5+ and 3+, respectively. Strong relaxor characteristics were revealed by the temperature-dependent dielectric properties of the ceramics. Typical square polarization-electric field ( P- E) hysteresis loops were observed in the samples with doping content lower than 0.005. However, with further increasing the doping content ( x = 0.007 and 0.009), round P- E hysteresis loops were observed due to the high conductivity of these samples. Moreover, when the doping content was less than 0.005, the ceramic samples exhibited good piezoelectric properties. Specially, when the doping content was 0.001, the piezoelectric constant d 33 and electromechanical coupling coefficient k p of the sample were 197 pC/N and 22%, respectively. However, further addition would deteriorate both the dielectric and piezoelectric properties.

Thermal evolution behavior and fluid dynamics during laser additive manufacturing of Al-based nanocomposites: Underlying role of reinforcement weight fraction

NASA Astrophysics Data System (ADS)

Gu, Dongdong; Yuan, Pengpeng

2015-12-01

In this study, a three-dimensional transient computational fluid dynamics model was established to investigate the influence of reinforcement weight fraction on thermal evolution behavior and fluid dynamics during selective laser melting (SLM) additive manufacturing of TiC/AlSi10Mg nanocomposites. The powder-to-solid transition and nonlinear variation of thermal physical properties of as-used materials were considered in the numerical model, using the Gaussian distributed volumetric heat source. The simulation results showed that the increase of operating temperature and the resultant formation of larger melt pool were caused by the increase of weight fraction of reinforcement. The Marangoni convection was intensified using a larger reinforcement content, accelerating the coupled motion of fluid and solid particles. The circular flows appeared when the TiC content reached 5.0 wt. % and the larger-sized circular flows were present as the reinforcement content increased to 7.5 wt. %. The experimental study on surface morphologies and microstructures on the polished sections of SLM-processed TiC/AlSi10Mg nanocomposite parts was performed. A considerably dense and smooth surface free of any balling effect and pore formation was obtained when the reinforcement content was optimized at 5.0 wt. %, due to the sufficient liquid formation and moderate Marangoni flow. Novel ring-structured reinforcing particulates were tailored because of the combined action of the attractive effect of centripetal force and repulsive force, which was consistent with the simulation results.

Corrosion behavior and pitting susceptibility of in-situ Ti-based metallic glass matrix composites in 3.5 wt.% NaCl solutions

NASA Astrophysics Data System (ADS)

Xu, K. K.; Lan, A. D.; Yang, H. J.; Han, P. D.; Qiao, J. W.

2017-11-01

The Ti62Zr12V13Cu4Be9, Ti58Zr16V10Cu4Be12, Ti46Zr20V12Cu5Be17, and Ti40Zr24V12Cu5Be19 metallic glass matrix composites (MGMCs) were prepared by copper mould casting. The corrosion resistance and the pitting susceptibility of Ti-based MGMCs were tested on their cross-sectional areas in 3.5 wt.% NaCl solutions by potentiodynamic polarization measurements. The composites with lower Ti contents (Ti40Zr24V12Cu5Be19 and Ti46Zr20V12Cu5Be17) exhibit a low resistance to the chloride induced pitting and local corrosion. The preferential dissolution of amorphous matrix is explained by the high chemical reactivity of beryllium element compared to that of stable dendrites and by the detected lower Ti and V contents. However, fairly good passivity was found in the composite with higher Ti contents (Ti62Zr12V13Cu4Be9). XPS measurements revealed that protective Ti-enriched oxide film was formed on the composite surface, additionally, lower content of beryllium element in amorphous matrix hinder the selective corrosion of amorphous matrix. The assessment of experimental observation leads to a proposed corrosion mechanism involving selective dissolution of amorphous matrix and chloride induced pitting process.

Titanium Dioxide Coating Prepared by Use of a Suspension-Solution Plasma-Spray Process

NASA Astrophysics Data System (ADS)

Du, Lingzhong; Coyle, Thomas W.; Chien, Ken; Pershin, Larry; Li, Tiegang; Golozar, Mehdi

2015-08-01

Titanium dioxide coatings were prepared from titanium isopropoxide solution containing nano TiO2 particles by use of a plasma-spray process. The effects of stand-off distance on coating composition and microstructure were investigated and compared with those for pure solution precursor and a water-based suspension of TiO2. The results showed that the anatase content of the coating increased with increasing stand-off distance and the rate of deposition decreased with increasing spray distance. Anatase nanoparticles in solution were incorporated into the coatings without phase transformation whereas most of the TiO2 in the precursor solution was transformed into rutile. The microstructure of preserved anatase particles bound by rutile improved the efficiency of deposition of the coating. The amount of anatase phase can be adjusted by variation of the ratio of solution to added anatase TiO2 nanoparticles.

Effect of CeO2 on TiC Morphology in Ni-Based Composite Coating

NASA Astrophysics Data System (ADS)

Cai, Yangchuan; Luo, Zhen; Chen, Yao

2018-03-01

The TiC/Ni composite coating with different content of CeO2 was fabricated on the Cr12MoV steel by laser cladding. The microstructure of cladding layers with the different content of CeO2 from the bottom to the surface is columnar crystal, cellular crystal, and equiaxed crystal. When the content of CeO2 is 0 %, the cladding layer has a coarse and nonuniform microstructure and TiC particles gathering in the cladding layer, and then the wear resistance was reduced. Appropriate rare-earth elements refined and homogenised the microstructure and enhanced the content of carbides, precipitated TiC particles and original TiC particles were spheroidised and refined, the wear resistance of the cladding layer was improved significantly. Excessive rare-earth elements polluted the grain boundaries and made the excessive burning loss of TiC particles that reduced the wear resistance of the cladding layer.

Tempering Behavior of TiC-Reinforced SKD11 Steel Matrix Composite

NASA Astrophysics Data System (ADS)

Hwang, Ji-In; Kim, Seong Hoon; Heo, Yoon-Uk; Kim, Dae Ha; Hwang, Keum-Cheol; Suh, Dong-Woo

2018-05-01

TiC-reinforced SKD11 steel matrix composite, fabricated by a pressure infiltration casting, undergoes monotonic decrease in hardness as tempering temperature increases. Element mappings by TEM-EDS and thermodynamic calculation indicate that remarkable redistribution of V between the reinforcement and the steel matrix occurs by partial dissolution and re-precipitation of MC carbides upon casting process. The absence of secondary hardening is led by the enrichment of V in the reinforcement that reduces the V content in the steel matrix; this reduction in V content makes the precipitation of fine VC sluggish during the tempering.

Tempering Behavior of TiC-Reinforced SKD11 Steel Matrix Composite

NASA Astrophysics Data System (ADS)

Hwang, Ji-In; Kim, Seong Hoon; Heo, Yoon-Uk; Kim, Dae Ha; Hwang, Keum-Cheol; Suh, Dong-Woo

2018-03-01

TiC-reinforced SKD11 steel matrix composite, fabricated by a pressure infiltration casting, undergoes monotonic decrease in hardness as tempering temperature increases. Element mappings by TEM-EDS and thermodynamic calculation indicate that remarkable redistribution of V between the reinforcement and the steel matrix occurs by partial dissolution and re-precipitation of MC carbides upon casting process. The absence of secondary hardening is led by the enrichment of V in the reinforcement that reduces the V content in the steel matrix; this reduction in V content makes the precipitation of fine VC sluggish during the tempering.

A reevaluation of spectral ratios for lunar mare TiO2 mapping

NASA Technical Reports Server (NTRS)

Johnson, Jeffrey R.; Larson, Stephen M.; Singer, Robert B.

1991-01-01

The empirical relation established by Charette et al. (1974) between the 400/560-nm spectral ratio of mature mare soils and weight percent TiO2 has been used extensively to map titanium content in the lunar maria. Relative reflectance spectra of mare regions show that a reference wavelength further into the near-IR, e.g., above 700 nm, could be used in place of the 560-nm band to provide greater contrast (a greater range of ratio values) and hence a more sensitive indicator of titanium content. An analysis of 400/730-nm ratio values derived from both laboratory and telescopic relative reflectance spectra suggests that this ratio provides greater sensitivity to TiO2 content than the 400/560-nm ratio. The increased range of ratio values is manifested in higher contrast 400/730-nm ratio images compared to 400/560-nm ratio images. This potential improvement in sensivity encourages a reevaluation of the original Charette et al. (1974) relation using the 400/730-nm ratio.

Experimental and simulation studies on grain growth in TiC and WC-based cermets during liquid phase sintering

NASA Astrophysics Data System (ADS)

Shin, Soon-Gi

2000-06-01

The grain growth behaviors of TiC and WC particles in TiC-Ni, TiC-Mo2C-Ni, WC-Co and WC-VC-Co alloys during liquid phase sintering were investigated for different Ni or Co contents and compared with the results of Monte Carlo simulations. In the experimental study, TiC-Ni and WC-Co alloys had a maximum grain size at a certain liquid volume fraction, while the grain size in TiC-Mo2C-Ni and WC-VC-Co alloys increased monotonically with an increasing liquid volume fraction. These results mean that the grain growth of these alloys cannot be explained by the conventional mechanisms for Ostwald ripening, namely diffusion or reaction controlled processes. Monte Carlo simulations with different energy relationships between solidliquid interfaces predicted the effect of the liquid volume fraction on grain size similar to the experimental results. The contiguous boundaries between solid (carbide) particles appear to influence the grain growth behavior in TiC- and WC-based alloys during liquid phase sintering.

Influence of V2O5 Content on the Gas-Based Direct Reduction of Hongge Vanadium Titanomagnetite Pellets with Simulated Shaft Furnace Gases

NASA Astrophysics Data System (ADS)

Li, Wei; Fu, Guiqin; Chu, Mansheng; Zhu, Miaoyong

2018-01-01

The influence of V2O5 content on the gas-based direct reduction of Hongge vanadium titanomagnetite pellets (HVTMP) was investigated with simulated shaft furnace gases, and the content levels were selected as 0 wt.%, 2 wt.%, 4 wt.%, and 6 wt.%, respectively. The results indicated that, with the increase of V2O5 content, the reduction was accelerated at an early stage due to the increase of the original porosity of the HVTMP. However, as the reduction proceeded, a slowing down in the reduction rate was observed, which was attributed to the formation of hardly reducible Fe2VO4. Major phases of reduced HVTMP were Fe2VO4, FeTiO3, and metallic iron. The morphology showed that the size of metallic iron particles of reduced HVTMP decreased with the increase of V2O5 content, V-bearing oxides embedded into the Ti-rich phases, and further reduction was restricted. This study not only established a relationship between the V2O5 content of HVTMP and its reduction behavior but could also contribute greatly to the effective utilization of Hongge vanadium titanomagnetite in shaft furnace.

Preparation and Properties of (YCa)(TiMn)O3−δ Ceramics Interconnect of Solid Oxide Fuel Cells

PubMed Central

Liou, Yi-Cheng; Tsai, Wen-Chou; Yen, Hao-Hsuan; Chang, Yung-Chia

2015-01-01

(YCa)(TiMn)O3–δ ceramics prepared using a reaction-sintering process were investigated. Without any calcination involved, the mixture of raw materials was pressed and sintered directly. Y2Ti2O7 instead of YTiO3 formed when a mixture of Y2O3 and TiO2 with Y/Ti ratio 1/1 were sintered in air. Y2Ti2O7, YTiO2.085 and some unknown phases were detected in Y0.6Ca0.4Ti0.6Mn0.4O3–δ. Monophasic Y0.6Ca0.4Ti0.4Mn0.6O3–δ ceramics were obtained after 1400–1500 °C sintering. Dense Y0.6Ca0.4Ti0.4Mn0.6O3–δ with a density 4.69 g/cm3 was observed after 1500 °C/4 h sintering. Log σ for Y0.6Ca0.4Ti0.6Mn0.4O3–δ increased from –3.73 Scm–1 at 350 °C to –2.14 Scm–1 at 700 °C. Log σ for Y0.6Ca0.4Ti0.4Mn0.6O3–δ increased from –2.1 Scm–1 at 350 °C to –1.36 Scm–1 at 700 °C. Increasing Mn content decreased activation energy Ea and increased electrical conductivity. Reaction-sintering process is proved to be a simple and effective method to obtain (YCa)(TiMn)O3–δ ceramics for interconnects in solid oxide fuel cells. PMID:28793436

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grujić-Brojčin, M., E-mail: myramyra@ipb.ac.rs; Armaković, S.; Tomić, N.

The influence of La-doping in the range of 0.5–6.0 mol% on structural and morphological properties of TiO{sub 2} nanopowders synthesized by sol–gel routine has been investigated by XRPD, AFM, EDS and BET measurements, as well as Raman spectroscopy. The XRPD and Raman measurements have revealed the anatase phase as dominant in all nanopowders, with crystallite size decreasing from ∼ 15 nm in pure TiO{sub 2} to ∼ 12 nm in La-doped samples. The BET data suggest that all samples are fully mesoporous, with mean pore diameters in the range of ∼ 6–8 nm. The specific surface area and the complexitymore » of pore structure are greater in doped samples than in pure TiO{sub 2} sample. The spectroscopic ellipsometry has apparently shown that the band gap has been gradually increased with the increase of La content. The STM and STS techniques have been used successfully to evaluate the surface morphology and electronic properties of La-doped nanopowders. All investigated properties have been related to photocatalytic activity, tested in degradation of a metoprolol tartrate salt (0.05 mM), and induced by UV-radiation. All doped samples showed increased photocatalytic activity compared to pure TiO{sub 2}, among which the 0.65 mol% La-doped sample appeared to be the most efficient. - Highlights: • Effects of La-doping on structural, morphological and electronic properties of TiO{sub 2} nanopowders. • Surface morphology and electronic properties of La-doped nanopowders evaluated by STM/STS. • Spectroscopic ellipsometry shown gradual increase of bandgap with the increase of La content. • Photocatalytic activity of samples was tested in degradation of MET under UV light.« less

Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x AB2-type metal hydride alloys for electrochemical storage application: Part 1. Structural characteristics

NASA Astrophysics Data System (ADS)

Bendersky, L. A.; Wang, K.; Levin, I.; Newbury, D.; Young, K.; Chao, B.; Creuziger, A.

2012-11-01

The microstructures of a series of AB2-based metal hydride alloys (Ti12.5Zr21V10Cr8.5MnxCo1.5Ni46.5-x) designed to have different fractions of non-Laves secondary phases were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, and electron backscatter diffraction. The results indicate that the alloys contain a majority of hydrogen storage Laves phases and a minority of fine-structured non-Laves phases. Formation of the phases is accomplished by dendritic growth of a hexagonal C14 Laves phase. The C14 phase is followed by either a peritectic solidification of a cubic C15 Laves phase (low Mn containing alloys) or a C14 phase of different composition (high Mn containing alloys), and finally a B2 phase formed in the interdendritic regions (IDR). The interdendritic regions may then undergo further solid-state transformation into Zr7Ni10-type, Zr9Ni11-type and TiNi-type phases. As the Mn content in the alloy increases, the fraction of the C14 phase increases, whereas the fraction of C15 decreases. In the IDRs when the alloy's Mn content increases the Zr9Ni11 phases and Zr7Ni10 phase fraction first increases and then decreases, while the TiNi-based phase fraction first increases and then stabilized at 0.02. IDR compositions can be generally expressed as (Ti,Zr,V,Cr,Mn,Co)50Ni50, which accounted for 7-10% of the overall alloy volume fraction.

TiO2 effect on crystallization mechanism and physical properties of nano glass-ceramics of MgO-Al2O3-SiO2 glass system.

PubMed

Jo, Sinae; Kang, Seunggu

2013-05-01

The effect of TiO2 on the degree of crystallization, thermal properties and microstructure for MgO-Al2O3-SiO2 glass-ceramics system containing 0-13 wt% TiO2 and 0-1.5 wt% B2O3 in which the cordierite is the main phase was studied. Using Kissinger and Augis-Bennett equations, the activation energy, 510 kJ/mol and Avrami constant, 1.8 were calculated showing the surface-oriented crystallization would be preferred. The alpha-cordierite phase was generated in the glass-ceramics of containing TiO2 of 0-5.6 wt%. However, for the glass-ceramics of TiO2 content above 7 wt%, an alpha-cordierite disappeared and micro-cordierite phase was formed. The glass-ceramics of no TiO2 added had spherical crystals of few tens nanometer size spread in the matrix. As TiO2 content increased up to 5.6 wt%, a lump of dendrite was formed. In the glass-ceramics containing TiO2 7-13 wt%, in which the main phase is micro-cordierite, the dendrite crystal disappeared and a few hundred nanometer sized crystal particles hold tightly each other were generated. The thermal conductivity of glass-ceramics of both a-cordierite and micro-cordierite base decreased with TiO2 contend added. The thermal conductivity of glass-ceramics of 1.5 wt% TiO2 added was 3.4 W/mK which is 36% higher than that of glass-ceramics of no TiO2 added. The sintering temperature for 1.5 wt% TiO2 glass-ceramics was 965 degrees C which could be concluded as to apply to LTCC process for LED packaging.

Biocompatible Ni-free Zr-based bulk metallic glasses with high-Zr-content: compositional optimization for potential biomedical applications.

PubMed

Hua, Nengbin; Huang, Lu; Chen, Wenzhe; He, Wei; Zhang, Tao

2014-11-01

The present study designs and prepares Ni-free Zr60+xTi2.5Al10Fe12.5-xCu10Ag5 (at.%, x=0, 2.5, 5) bulk metallic glasses (BMGs) by copper mold casting for potential biomedical application. The effects of Zr content on the in vitro biocompatibility of the Zr-based BMGs are evaluated by investigating mechanical properties, bio-corrosion behavior, and cellular responses. It is found that increasing the content of Zr is favorable for the mechanical compatibility with a combination of low Young's modulus, large plasticity, and high notch toughness. Electrochemical measurements demonstrate that the Zr-based BMGs are corrosion resistant in a phosphate buffered saline solution. The bio-corrosion resistance of BMGs is improved with the increase in Zr content, which is attributed to the enrichment in Zr and decrease in Al concentration in the surface passive film of alloys. Regular cell responses of mouse MC3T3-E1 cells, including cell adhesion and proliferation, are observed on the Zr-Ti-Al-Fe-Cu-Ag BMGs, which reveals their general biosafety. The high-Zr-based BMGs exhibit a higher cell proliferation activity in comparison with that of pure Zr and Ti-6Al-4V alloy. The effects of Zr content on the in vitro biocompatibility can be used to guide the future design of biocompatible Zr-based BMGs. Copyright © 2014 Elsevier B.V. All rights reserved.

Bioaccumulation, Sub-acute Toxicity, and Tissue Distribution of Engineered Titanium Dioxide (TiO2) Nanoparticles in Goldfish (Carassius auratus)

PubMed Central

Ates, Mehmet; Demir, Veysel; Adiguzel, Ragip; Arslan, Zikri

2014-01-01

The increased use of nano-sized materials is likely to result in the release of these particles into the environment. It is, however, unclear if these materials are harmful to aquatic animals. In this study, the sub-lethal effects of exposure of low and high concentrations of titanium dioxide nanoparticles (TiO2 NPs) on goldfish (Carassius auratus) were investigated. Tissues, including intestine, gills, muscle, and brain were analyzed for Ti content by ICP-MS. Accumulation of TiO2 NPs increased from 42.71 to 110.68 ppb in the intestine and from 4.10 to 9.86 ppb in the gills of the goldfish with increasing exposure dose from 10 to 100 mg/L TiO2 NPs. No significant accumulation in the muscle and brain of the fish was detected. Malondialdehyde (MDA) as a biomarker of lipid oxidation was detected in the liver of the goldfish. Moreover, TiO2 NPs exposure inhibited growth of the goldfish. Although there was an increase (8.1%) in the body weights of the goldfish for the control group, in the low and high exposure groups 1.8% increase and 19.7 % decrease were measured respectively. PMID:25383077

Microstructure Analysis of Ti-xPt Alloys and the Effect of Pt Content on the Mechanical Properties and Corrosion Behavior of Ti Alloys

PubMed Central

Song, Ho-Jun; Han, Mi-Kyung; Jeong, Hyeon-Gyeong; Lee, Yong-Tai; Park, Yeong-Joon

2014-01-01

The microstructure, mechanical properties, and corrosion behavior of binary Ti-xPt alloys containing 5, 10, 15 and 20 wt% Pt were investigated in order to develop new Ti-based dental materials possessing superior properties than those of commercially pure titanium (cp-Ti). All of the Ti-xPt (x = 5, 10, 15, 20) alloys showed hexagonal α-Ti structure with cubic Ti3Pt intermetallic phase. The mechanical properties and corrosion behavior of Ti-xPt alloys were sensitive to the Pt content. The addition of Pt contributed to hardening of cp-Ti and to improving its oxidation resistance. Electrochemical results showed that the Ti-xPt alloys exhibited superior corrosion resistance than that of cp-Ti. PMID:28788660

Investigation of optical properties of ternary Zn-Ti-O thin films prepared by magnetron reactive co-sputtering

NASA Astrophysics Data System (ADS)

Netrvalová, Marie; Novák, Petr; Šutta, Pavol; Medlín, Rostislav

2017-11-01

Zn-Ti-O thin films with different concentrations of titanium were deposited by reactive magnetron co-sputtering in a reactive Ar/O2 atmosphere from zinc and titanium targets. It was found that with increasing Ti content the structure of the films gradually changes from a fully crystalline pure ZnO wurtzite structure with a strongly preferred columnar orientation to an amorphous Zn-Ti-O material with 12.5 at.% Ti. The optical parameters (spectral refractive index and extinction coefficient, optical band gap) and thickness of the films were analysed by the combined evaluation of ellipsometric measurements and measurements of transmittance on a UV-vis spectrophotometer. For evaluation of optical parameters was used Cody-Lorentz dispersion model.

Ultrasonic spray pyrolysis synthesis of reduced graphene oxide/anatase TiO2 composite and its application in the photocatalytic degradation of methylene blue in water.

PubMed

Park, Jeong-Ann; Yang, Boram; Lee, Joongki; Kim, In Gyeom; Kim, Jae-Hyun; Choi, Jae-Woo; Park, Hee-Deung; Nah, In Wook; Lee, Sang-Hyup

2018-01-01

Reduced graphene oxide (RGO)/anatase TiO 2 composite was prepared using a simple one-step technique-ultrasonic spray pyrolysis-in order to inhibit the aggregation of TiO 2 nanoparticles and to improve the photocatalytic performance for degradation of methylene blue (MB). Different proportions (0-5 wt%) of RGO/TiO 2 composites were characterized by scanning electronic microscopy (SEM), dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), Raman spectroscopy, UV-vis spectroscopy, and electrochemical impedance spectroscopy (EIS) to verify mechanism. From these analysis, TiO 2 nanoparticles are distributed uniformly on the RGO sheets with crumpled shape during ultrasonic spray pyrolysis and surface area is increasing by increasing portion of RGO. Band gap of RGO 5 /TiO 2 (5 wt% of RGO) composite is 2.72 eV and band gap was reduced by increasing portion of RGO in RGO/TiO 2 composites. The RGO 5 /TiO 2 composite was superior to other lower content of RGO/TiO 2 composites with a rapid transport of charge carriers and an effective charge separation. The highest removal efficiency of MB was obtained at the RGO 5 /TiO 2 composite under UVC irradiation, which coincided with the EIS, and the optimal dose of the composite was determined to be 0.5 g/L. The RGO 5 /TiO 2 composite improve the photocatalytic degradation rate of MB over the TiO 2 due to a retardation of electron-hole recombination. The MB adsorption capacity and photocatalytic degradation efficiency were greatly affected by pH changes and increased with increasing pH due to electrostatic interactions and generation of more hydroxyl radicals. The reusability of RGO 5 /TiO 2 composite was examined during 3 cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Photocatalytic Activity of W-Doped TiO2 Nanofibers for Methylene Blue Dye Degradation.

PubMed

Song, Yo-Seung; Cho, Nam-Ihn; Lee, Myung-Hyun; Kim, Bae-Yeon; Lee, Deuk Yong

2016-02-01

Photocatalytic degradation of methylene blue (MB) in water was examined using W-doped TiO2 nanofibers prepared by a sol-gel derived electrospinning and subsequent calcination for 4 h at 550 degrees C. Different concentrations of W dopant in the range of 0 to 8 mol% were synthesized to evaluate the effect of W concentration on the photocatalytic activity of TiO2. XRD results indicated that the undoped TiO2 is composed of anatase and rutile phases. The rutile phase was transformed to anatase phase completely with the W doping. Among W-TiO2 catalysts, the 2 mol% W-TiO2 catalyst showed the highest MB degradation rate. The degradation kinetic constant increased from 1.04 x 10(-3) min(-1) to 3.54 x 10(-3) min(-1) with the increase of W doping from 0 to 2 mol%, but decreased down to 1.77 x 10(-3) min(-1) when the W content was 8 mol%. It can be concluded that the degradation of MB under UV radiation was more efficient with W-TiO2 catalysts than with pure TiO2-

Effect of TiO2 on electron paramagnetic resonance, optical transmission and dc conductivity of vanadyl doped sodium borate glasses.

PubMed

Agarwal, A; Seth, V P; Gahlot, P; Goyal, D R; Arora, M; Gupta, S K

2004-11-01

Glass systems with composition xTiO2.(30 - x)Na2O.70B2O3 (series I) and xTiO2.(70 - x)B2O3.30Na2O (series II) containing 2 mol% V2O5 have been prepared (0 < or = x < or = 7, mol%) by normal melt-quenching. The electron paramagnetic resonance (EPR) spectra of VO2+ ions have been recorded in the X-band (approximately 9.13 GHz) at room temperature. Spin Hamiltonian parameters, gparallel, gperpendicular, Aparallel, Aperpendicular, the dipolar hyperfine coupling parameter (P) and the Fermi contact interaction parameter (K) have been calculated. The increase in Deltagparallel/Deltagperpendicular with increase in TiO2 content in series I shows that the octahedral symmetry of V4+O6 complex is reduced, whereas in series II the octahedral symmetry is improved with increase in x. The decrease in P, in both the series, indicates that the 3dxy orbit expands with increase in mol% of TiO2. The molecular orbital coefficients, alpha2 and gamma2 have been calculated by recording the optical transmission spectra in the range 500-850 nm. alpha2 and gamma2 increase with increase in x in both the series, which indicates that, the covalency of the vanadium oxygen bonds decreases. The dc conductivity sigma, decreases and activation energy, W increases with increase in TiO2:Na2O ratio whereas with increase in TiO2:B2O3 ratio the variation in sigma and W is within experimental error.

Dielectric properties of Ba0.6Sr0.4TiO3-La(B0.5Ti0.5)O3 (B=Mg, Zn) ceramics.

PubMed

Xu, Yebin; Liu, Ting; He, Yanyan; Yuan, Xiao

2009-11-01

Ba(0.6)Sr(0.4)TiO(3)-La(B(0.5)Ti(0.5))O(3) (B = Mg, Zn) ceramics were prepared by a solid-state reaction method, and their microwave dielectric characteristics and tunability were investigated. The ferroelectric-dielectric solid solutions with cubic perovskite structures were obtained for compositions of 10 to 60 mol% La(Mg(0.5)Ti(0.5))O(3) and 10 to 50 mol% La(Zn(0.5)Ti(0.5))O(3). With the increase of linear oxide dielectric content, the dielectric constant and tunability were decreased and Qf was increased. Ba(0.6)Sr(0.4)TiO(3)-La(Mg(0.5)Ti(0.5))O(3) has better dielectric properties than Ba(0.6)Sr(0.4)TiO(3)-La(Zn(0.5)Ti(0.5))O(3). 0.9Ba(0.6)Sr(0.4)TiO(3)-0.1La(Mg(0.5)Ti(0.5))O(3) has a dielectric constant epsilon = 338.2, Qf = 979 GHz and a tunability of was 3.7% at 100 kHz under 1.67 kV/mm. The Qf value of 0.5Ba(0.6)Sr(0.4)TiO(3)- 0.5La(Mg(0.5)Ti(0.5))O(3) reached 9367 GHz, but the tunable properties were lost.

The light transmission and distribution in an optical fiber coated with TiO2 particles.

PubMed

Wang, Wen; Ku, Young

2003-03-01

The light delivery and distribution phenomena along the optical fiber coated with the P-25 TiO(2) particles by dipping was investigated. The surface properties (coverage, roughness and thickness) of the TiO(2) layer coated on the optical fiber were characterized by SEM micrographs. For TiO(2) layer prepared from solutions containing less than 20 wt.% of TiO(2) slurry, the thickness of layer was increased linearly with the TiO(2) slurry content in solutions. The UV light intensity transmitted along a TiO(2)-coated optical fiber decreased more rapidly than that transmitted along a non-coated fiber. Based on the experimental results, the light intensity distribution around a coated optical fiber was modeled to determine the optimum configuration for the design of optical fiber reactors under various operational conditions. Copyright 2002 Elsevier Science Ltd.

Microstructure refinement and mechanical properties improvement by developing IAF on inclusions in Ti–Al complex deoxidized HSLA steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, M., E-mail: jiangmin@ustb.edu.cn; Wang, X.H.; Hu, Z.Y.

2015-10-15

The present study focused on microstructure refinement in Ti–Al complex deoxidized low alloy structural steel by developing IAF on inclusions. The goal was to establish more determined relation between Ti, Al in steel and the produced microstructures. In steel sample with Ti and Al contents of 0.0035% and 0.0004%, respectively, IAF was well developed by inclusions characterized by TiO{sub x}–MnO oxide cores enwrapped by (MnO–SiO{sub 2}–Al{sub 2}O{sub 3})–MnS or (MnO–SiO{sub 2})–MnS surface layers. With the rise of Ti and Al contents, IAF volume decreased greatly because of different inclusion chemistry, TiO{sub x} + MnS, TiO{sub x}–Al{sub 2}O{sub 3} or Al{submore » 2}O{sub 3}, which inhibit the formation of IAF. Thermodynamic calculations were carried out for optimal Ti and Al contents in steel to target inclusions with proper chemistry for nucleating IAF. These laboratorial findings were successfully applied and reproducibly observed in pilot trials. It was indicated that low temperature impact toughness at 0 °C and − 20 °C of the produced medium plate was effectively improved despite lower Ti contents than common process, which was very meaningful in saving the cost of high Ti content steels. - Highlights: • IAF volume showed close relationship to Ti or Al contents. • To target IAF, there is no need to add too many titanium alloys. • Optimal Ti and Al were about 0.0020–0.0060% and 0.0005–0.0020%, respectively. • Impact toughness of steel plate at 0 °C and − 20 °C was successfully improved.« less

Hair chemical element contents and influence factors of reproductive-age women in the West Ujimqin Banner, Inner Mongolia, China.

PubMed

Zhou, Shanshan; Yuan, Haodong; Ma, Xiaoling; Liu, Ying

2017-01-01

Women have an increased risk for chemical element deficiencies during reproductive age, particularly due to higher chemical element requirements and poor diets. Twenty-one chemical elements (Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Se, Si, Sn, Sr, Ti, V and Zn) in hair samples, which were collected from 71 non-pregnant and 236 pregnant women living in the West Ujimqin Banner, central Inner Mongolia, China, were measured, and the environment, dietary habits and ethnic group influence factors associated with the biomarker were analyzed. The results indicated that the average values of the chemical element contents from hair were greatly different compared to those from other areas, especially the Al, Cd, Pb, Ca and Sr contents. There was no significant difference among the three ethnicities for any element except Mn and Ti in non-pregnant women. Compared to non-pregnant women, in the first trimester group, the levels of nine chemical elements (Ba, Cd, Cu, Pb, Se, Si, Sn and Ti) decreased, while the others increased, and the contents of all of the chemical elements decreased in the second trimester group, while in the third trimester, there was a slight increase. Three chemical elements (Cu, Mn and Zn) displayed a synergistic correlation between each other in the third trimester group, which may protect the placenta from some oxidant damage. The high levels of Cd and Pb in hair likely originate from house renovations and traffic pollution. This study provided basic and useful information on the levels of chemical elements in reproductive-age women, and the results of this study are helpful to control the contents and improve the health of pregnant and non-pregnant women. Copyright © 2016 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Wei; Boehlert, C. J.

The tensile properties of extruded Ti 6Al 4V xB alloys (wt.%) were evaluated in an orientation perpendicular to the extrusion direction at room-temperature and 455 C. The extrusion process preferentially oriented the basal plane of -Ti perpendicular to the extrusion axis. This strong - phase texture resulted in tensile anisotropy. The tensile strength in the transverse orientation was lower than that in the longitudinal orientation, but it remained greater than that for the ascast Ti 6Al 4V. The TiB phasewas aligned in the extrusion direction and increased B content was found to weaken the -phase texture, causing a weakening ofmore » tensile anisotropy. Debonding was not observed during the tensile tests in the transverse orientation, indicating a strong interface bond exists between the TiB phase and the two-phase ( + ) Ti 6Al 4V matrix.« less

Mineralogy and chemistry of Ti-bearing lunar soils: Effects on reflectance spectra and remote sensing observations

NASA Astrophysics Data System (ADS)

Coman, Ecaterina O.; Jolliff, Bradley L.; Carpenter, Paul

2018-05-01

This paper presents results of coordinated ultraviolet and visible wavelength reflectance measurements, X-ray diffraction analyses of mineral components, and micro X-ray fluorescence analyses of Ti concentrations of 13 lunar soil samples (<210 μm) that span a range of maturity and TiO2 contents. Results of these analyses are used to determine the effects of soil maturity, TiO2 concentration, and specific mineralogical makeup, especially ilmenite content, on the ultraviolet/visible (UV/VIS) ratio for application to remote sensing observations of the Moon and other airless bodies. We find that measured ilmenite weight percent correlates highly with measured TiO2 concentrations. Thus, the ilmenite content is a good predictor of TiO2 concentration. Ilmenite is the main contributor of TiO2 for soils with greater than about 2 wt.% TiO2, so we take the effects of TiO2 on reflectance spectra to be essentially those of ilmenite. Constraining the data set to eight mature Apollo soils, we find that among the UV/VIS ratios from laboratory-measured spectra, the 321/415 nm ratio shows the best correlation with TiO2 and ilmenite. Moreover, for soils with similar maturity in the submature to mature range, those with higher TiO2 have higher 321/415 UV/VIS ratios. Finally, the correlation between TiO2 content and 321/415 ratio in samples measured in the lab appears weaker than for the same relationship using the Lunar Reconnaissance Orbiter (LRO) Wide Angle Camera (WAC) spectral data for the 321/415 ratio of Apollo ground-truth sites. The correlation between lab-derived 321/415 ratios and TiO2 content for measured samples improves when low-maturity samples are excluded from the dataset, implying that the LROC WAC spectra at 400 m/pix spatial resolution senses mostly mature soil.

Deposition and characterization of TiAlSiN nanocomposite coatings prepared by reactive pulsed direct current unbalanced magnetron sputtering

NASA Astrophysics Data System (ADS)

Barshilia, Harish C.; Ghosh, Moumita; Shashidhara; Ramakrishna, Raja; Rajam, K. S.

2010-08-01

This work reports the performance of high speed steel drill bits coated with TiAlSiN nanocomposite coating at different Si contents (5.5-8.1 at.%) prepared using a four-cathode reactive pulsed direct current unbalanced magnetron sputtering system. The surface morphology of the as-deposited coatings was characterized using field emission scanning electron microscopy. The crystallographic structure, chemical composition and bonding structure were evaluated using X-ray diffraction, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, respectively. The corrosion behavior, mechanical properties and thermal stability of TiAlSiN nanocomposite coatings were also studied using potentiodynamic polarization, nanoindentation and Raman spectroscopy, respectively. The TiAlSiN coating thickness was approximately 2.5-2.9 μm. These coatings exhibited a maximum hardness of 38 GPa at a silicon content of approximately 6.9 at.% and were stable in air up to 850 °C. For the performance evaluation, the TiAlSiN coated drills were tested under accelerated machining conditions by drilling a 12 mm thick 304 stainless steel plate. Under dry conditions the uncoated drill bits failed after drilling 50 holes, whereas, TiAlSiN coated drill bits (Si = 5.5 at.%) drilled 714 holes before failure. Results indicated that for TiAlSiN coated drill bits the tool life increased by a factor of more than 14.

Fabrication of predominantly Mn4+ -doped TiO2 nanoparticles under equilibrium conditions and their application as visible-light photocatalyts.

PubMed

Wang, Lijie; Fan, Jiajie; Cao, Zetan; Zheng, Yichao; Yao, Zhiqiang; Shao, Guosheng; Hu, Junhua

2014-07-01

The chemical state of a transition-metal dopant in TiO(2) can intrinsically determine the performance of the doped material in applications such as photocatalysis and photovoltaics. In this study, manganese-doped TiO2 is fabricated by a near-equilibrium process, in which the TiO(2) precursor powder precipitates from a hydrothermally obtained transparent mother solution. The doping level and subsequent thermal treatment influence the morphology and crystallization of the TiO(2) samples. FTIR spectroscopy and X-ray photoelectron spectroscopy analyses indicate that the manganese dopant is substitutionally incorporated by replacing Ti(4+) cations. The absorption band edge can be gradually shifted to 1.8 eV by increasing the nominal manganese content to 10 at %. Manganese atoms doped into the titanium lattice are associated with the dominant 4+ valence oxidation state, which introduces two curved, intermediate bands within the band gap and results in a significant enhancement in photoabsorption and the quantity of photogenerated hydroxyl radicals. Additionally, the high photocatalytic performance of manganese-doped TiO(2) is also attributed to the low oxygen content, owing to the equilibrium fabrication conditions. This work provides an important strategy to control the chemical and defect states of dopants by using an equilibrium fabrication process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser

NASA Astrophysics Data System (ADS)

Liang, Chunyong; Wang, Hongshui; Yang, Jianjun; Li, Baoe; Yang, Yang; Li, Haipeng

2012-11-01

Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser (FSL) was studied in this work. The surface characteristics of the laser treated NiTi alloys were investigated by scanning electron microscopy (SEM), atom force microscopy (AFM), X-ray diffractometry (XRD) and X-ray photoelectron spectrum (XPS). The biocompatibility was evaluated by in vitro cell culture test. The results showed that, grooves, ripples, which covered by nanoparticles were formed on the sample surfaces, and the Ni/Ti ratio on the alloy surface increased with increasing laser energy. The crystal structure was not changed by laser treatment. However, the cell culture test proved that the micro-patterns induced by FSL were beneficial to improve the biocompatibility of NiTi alloys: the growth of osteoblasts oriented along the grooves, a large amount of synapses and filopodias were formed due to the ripples, holes and nanoparticles on the alloy surface, and the proliferation rate and alkaline phosphatase (ALP) content of cells were increased after FSL treatment. However, due to the toxicity of Ni ions on cell growth, the NiTi alloy surface should not be treated by laser fluence of more than 3.82 J/cm2 to obtain the ideal biocompatibility.

Effect of Cr-N codoping on structural phase transition, Raman modes, and optical properties of TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Hassnain Jaffari, G.; Tahir, Adnan; Ali, Naveed Zafar; Ali, Awais; Qurashi, Umar S.

2018-04-01

Noncompensated cation-anion codoping in TiO2 nanoparticles has been achieved by a chemical synthesis route. Significant reduction in the optical bandgap and enhancement in the absorption of visible light have been observed. Structural phase transformation has been tracked in detail as a function of doping and heat treatment temperature. Anatase to rutile phase transition temperature for doped samples was higher in comparison to the pure TiO2 nanoparticles. Nitrogen and chromium addition increases the phase transformation barrier, where the effect of the former dopant is of more significance. The Raman results showed an increase in the oxygen content with higher post annealing temperatures. With Cr incorporation, the peak associated with the Eg mode has been found to shift towards a higher wave number, while with nitrogen incorporation, the shift was towards a lower wave number. A decrease in reflectance with N co-doping for all samples, irrespective of phase and annealing temperatures, has been observed. In compositions with nitrogen of the same content, bandgap reduction was higher in the rutile phase in comparison to the anatase phase. In general, overall results revealed that with a higher loading fraction of ammonia, the N content increases, while Cr addition prevents nitrogen loss even up to high post annealing temperatures, i.e., 850 °C.

Fabrication of low-cost beta-type Ti-Mn alloys for biomedical applications by metal injection molding process and their mechanical properties.

PubMed

Santos, Pedro Fernandes; Niinomi, Mitsuo; Liu, Huihong; Cho, Ken; Nakai, Masaaki; Itoh, Yoshinori; Narushima, Takayuki; Ikeda, Masahiko

2016-06-01

Titanium and its alloys are suitable for biomedical applications owing to their good mechanical properties and biocompatibility. Beta-type Ti-Mn alloys (8-17 mass% Mn) were fabricated by metal injection molding (MIM) as a potential low cost material for use in biomedical applications. The microstructures and mechanical properties of the alloys were evaluated. For up to 13 mass% Mn, the tensile strength (1162-938MPa) and hardness (308-294HV) of the MIM fabricated alloys are comparable to those of Ti-Mn alloys fabricated by cold crucible levitation melting. Ti-9Mn exhibits the best balance of ultimate tensile strength (1046MPa) and elongation (4.7%) among the tested alloys, and has a Young's modulus of 89GPa. The observed low elongation of the alloys is attributed to the combined effects of high oxygen content, with the presence of interconnected pores and titanium carbides, the formation of which is due to carbon pickup during the debinding process. The elongation and tensile strength of the alloys decrease with increasing Mn content. The Ti-Mn alloys show good compressive properties, with Ti-17Mn showing a compressive 0.2% proof stress of 1034MPa, and a compressive strain of 50%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dielectric and Nonohmic Properties of CaCu3Ti4O12/SrTiO3 Ceramics

NASA Astrophysics Data System (ADS)

Xue, Renzhong; Liu, Dewei; Chen, Zhenping; Dai, Haiyang; Chen, Jing; Zhao, Gaoyang

2015-04-01

In this work, (1 - x)CaCu3Ti4O12- xSrTiO3 [(1 - x)CCTO/ xST, x = 0% to 2%] ceramic samples were prepared by the solid-state reaction method. The dielectric and electrical properties of CaCu3Ti4O12 (CCTO) and CaCu3Ti4O12/SrTiO3 (CCTO/ST) ceramics were investigated. The results show that a small amount of Sr2+ can enter the lattice of CCTO. The mean grain size of the ceramic samples increased greatly for x = 0.5% and then decreased for x = 0.75% to 2%. ST addition and Sr2+ preferential occupancy in CCTO grains should be responsible for the change of the microstructure. Interestingly, the dielectric constant ( ɛ) of the 0.5% ST-added sample increased significantly while the dielectric loss (tan δ) remained low. With further increase of the ST content, the ɛ and tan δ values of the CCTO ceramics decreased monotonically while the nonlinear current-voltage properties were significantly enhanced. The change in the potential barrier height is thought to be the main cause for the opposite behaviors in the dielectric properties and nonohmic characteristics.

Short-term effects of TiO2, CeO2, and ZnO nanoparticles on metabolic activities and gene expression of Nitrosomonas europaea.

PubMed

Yu, Ran; Fang, Xiaohua; Somasundaran, Ponisseril; Chandran, Kartik

2015-06-01

Nanosized TiO2 (n-TiO2), CeO2 (n-CeO2), and ZnO (n-ZnO) and bulk ZnO were chosen for a 4-h exposure study on a model ammonia oxidizing bacterium, Nitrosomonas europaea. n-ZnO displayed the most serious cytotoxicity while n-TiO2 was the least toxic one. The change of cell morphologies, the retardance of specific oxygen uptake rates and ammonia oxidation rates, and the depression of amoA gene expressions under NP stresses were generally observed when the cell densities and membrane integrities were not significantly impaired yet. The TEM imaging and the synchrotron X-ray fluorescence microscopy of the NPs impacted cells revealed the increase of the corresponding intracellular Ti, Ce or Zn contents and suggested the intracellular NP accumulation. The elevation of intracellular S contents accompanied with higher K contents implied the possible activation of thiol-containing glutathione and thioredoxin production for NP stress alleviation. The NP cytotoxicity was not always a function of NP concentration. The 200 mg L(-1) n-TiO2 or n-CeO2 impacted cells displayed the similar ammonia oxidation activities but higher amoA gene expression levels than the 20 mg L(-1) NPs impacted ones. Such phenomenon further indicated the possible establishment of an anti-toxicity mechanism in N. europaea at the genetic level to redeem the weakened AMO activities along with the NP aggregation effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

Probing properties of the interfacial perimeter sites in TiO x /Au/SiO 2 with 2-propanol decomposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Yi Y.; Kung, Harold H.

The decomposition of 2-propanol was studied over SiO2, SiO2 with an overlayer of TiO2 (Ti/SiO2), Au/SiO2, and Au/SiO2 with an overlayer of TiO2 (Ti/[Au/SiO2]) at 170–190 °C. There was no reaction on SiO2. Propene was the only product on Ti/SiO2, and its rate of formation increased proportionally with the Ti content. Acetone was the major product (selectivity 65–99%) on all Au-containing catalysts. Its rate of formation also increased with Ti loading. In addition, small amounts of propene were also formed on Ti/[Au/SiO2] the rate of which increased with Ti loading. Characterization of the catalysts with N2 adsorption, STEM, DR-UV-vis spectroscopy,more » XPS, XANES and EXAFS suggested that the Ti formed an amorphous TiO2 overlayer on the catalyst. At high Ti loadings (4–5 wt.%), there were patches of thick porous TiO2 layer, and some microdomains of crystalline TiO2 could be detected. Au was present as 1–3 nm nanoparticles on all catalysts, before and after used in reaction. Only Lewis acid sites were detected based on results from pyridine adsorption, and their quantities increased with Ti loading. Based on the comparison of reaction rates, the dependence of the kinetics on 2-propanol partial pressure, the apparent activation energies, and the effect of co-feeding O2 among different catalysts, it was concluded that propene was formed on the TiO2 overlayer, acetone was formed primarily at the Au-TiO2 interfacial perimeter sites, and α-C-H bond breaking preceding acetone formation was more facile on Au at the interfacial site than other surface Au atoms. Implication of these results to the selective acetone formation in the oxidation of propane in the presence of a O2/H2 mixture was discussed.« less

Silica-Based and Borate-Based, Titania-Containing Bioactive Coatings Characterization: Critical Strain Energy Release Rate, Residual Stresses, Hardness, and Thermal Expansion.

PubMed

Rodriguez, Omar; Matinmanesh, Ali; Phull, Sunjeev; Schemitsch, Emil H; Zalzal, Paul; Clarkin, Owen M; Papini, Marcello; Towler, Mark R

2016-12-01

Silica-based and borate-based glass series, with increasing amounts of TiO₂ incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion) closer to the substrate's (Ti6Al4V) CTE, translating into higher mode I critical strain energy release rates of glasses and compressive residual stresses and strains at the coating/substrate interface, outperforming the silica-based glasses counterparts. An increase in the content of TiO₂ in the glasses results in an increase in the mode I critical strain energy release rate for both the bulk glass and for the coating/substrate system, proving that the addition of TiO₂ to the glass structure enhances its toughness, while decreasing its bulk hardness. Borate-based glass BRT3, with 15 mol % TiO₂ incorporated, exhibits superior properties overall compared to the other proposed glasses in this work, as well as 45S5 Bioglass ® and Pyrex.

Silica-Based and Borate-Based, Titania-Containing Bioactive Coatings Characterization: Critical Strain Energy Release Rate, Residual Stresses, Hardness, and Thermal Expansion

PubMed Central

Rodriguez, Omar; Matinmanesh, Ali; Phull, Sunjeev; Schemitsch, Emil H.; Zalzal, Paul; Clarkin, Owen M.; Papini, Marcello; Towler, Mark R.

2016-01-01

Silica-based and borate-based glass series, with increasing amounts of TiO2 incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion) closer to the substrate’s (Ti6Al4V) CTE, translating into higher mode I critical strain energy release rates of glasses and compressive residual stresses and strains at the coating/substrate interface, outperforming the silica-based glasses counterparts. An increase in the content of TiO2 in the glasses results in an increase in the mode I critical strain energy release rate for both the bulk glass and for the coating/substrate system, proving that the addition of TiO2 to the glass structure enhances its toughness, while decreasing its bulk hardness. Borate-based glass BRT3, with 15 mol % TiO2 incorporated, exhibits superior properties overall compared to the other proposed glasses in this work, as well as 45S5 Bioglass® and Pyrex. PMID:27916951

Reduction of hydrogen content in pure Ti

NASA Astrophysics Data System (ADS)

Ogiwara, N.; Suganuma, K.; Hikichi, Y.; Kamiya, J.; Kinsho, M.; Sukenobu, S.

2008-03-01

Pure Ti is adopted as a material for ducts and bellows at the proton accelerator 3 GeV-RCS in J-PARC project, because of its small residual radioactivity. In the particle accelerator, the H2 outgassing due to ion impact is often the dominant source of gas release. As the reduction of hydrogen content will probably suppress ion induced desorption, we attempted to reduce the hydrogen content in the Ti by in-situ vacuum baking. First, thermal desorption behavior and the change in hydrogen content after the heat treatment were investigated. Vacuum firing at temperatures higher than 550°C was effective in reducing the hydrogen content in the Ti. At the same time, the mechanical properties were monitored because grain growth leads to decrease in mechanical strength. Even after treatment at 750°C for 12 hr, the decreases in tensile and yield strength were so small (~10%) that we have no anxiety about the reduction of mechanical strength. Based upon the results of this study, vacuum firing has been applied to reduce the hydrogen content in the Ti bellows and ducts of the RCS machine.

A facile method to synthesize nitrogen and fluorine co-doped TiO2 nanoparticles by pyrolysis of (NH4)2TiF6

NASA Astrophysics Data System (ADS)

Chen, Daimei; Jiang, Zhongyi; Geng, Jiaqing; Zhu, Juhong; Yang, Dong

2009-02-01

The nitrogen and fluorine co-doped TiO2 (N-F-TiO2) nanoparticles of anatase crystalline structure were prepared by a facile method of (NH4)2TiF6 pyrolysis, and characterized by thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy etc. With the increase of calcination temperature, (NH4)2TiF6 decomposed into TiOF2 and NH4TiOF3 at first, and then formed anatase-type TiO2 with thin sheet morphology. H3BO3 as oxygen source can promote the formation of anatase TiO2, but decrease the F content in the N-F-TiO2 materials due to the formation of volatile BF3 during the precursor decomposition. The photocatalytic activity of the obtained N-F-TiO2 samples was evaluated by the methylene blue degradation under visible light, and all the samples exhibited much higher photocatalytic activity than P25. Moreover, the merits and disadvantages of this proposed method to prepare doped TiO2 are discussed.

Effect of surface plasmon resonance on the photocatalytic activity of Au/TiO2 under UV/visible illumination.

PubMed

Tseng, Yao-Hsuan; Chang, I-Guo; Tai, Yian; Wu, Kung-Wei

2012-01-01

In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

Effect of Exposure on the Mechanical Properties of Gamma MET PX

NASA Technical Reports Server (NTRS)

Draper, S. L.; Lerch, B. A.; Locci, I. E.; Shazly, M.; Prakash, V.

2004-01-01

The effect of a service environment exposure on the mechanical properties of a high Nb content TiAl alloy, Gamma MET PX , was assessed. Gamma MET PX, like other TiAl alloys, experiences a reduction of ductility following high temperature exposure. Exposure in Ar, air, and high-purity oxygen all resulted in a loss of ductility with the ductility reduction increasing with oxygen content in the exposure atmosphere. Embrittling mechanisms, including bulk microstructural changes, moisture induced environmental embrittlement, and near surface effects were investigated. The embrittlement has been shown to be a near-surface effect, most likely due to the diffusion of oxygen into the alloy.

Effect of 0.2 and 0.5% Ti on the microstructure and mechanical properties of 13Cr supermartensitic stainless steel

NASA Astrophysics Data System (ADS)

Lian, Yong; Huang, Jinfeng; Zhang, Jin; Zhang, Cheng; Gao, Wen; Zhao, Chao

2015-11-01

The effect that a 0, 0.2, and 0.5 wt.% titanium content has on the microstructure and mechanical properties of 13Cr supermartensitic stainless steel was investigated using an optical microscope, transmission electron microscope, and X-ray diffraction. The resultant microstructures of the three steels were tempered martensite with a reversed austenite dispersed throughout the matrix. Additionally, the formation of Cr-rich carbides was suppressed by stable Ti(C, N), which improved the strength without severely decreasing in the Ti-microalloyed steel toughness. Nano-precipitation of Ni3Ti was found for the 0.5 wt.% Ti steel during tempering, which significantly increased the strength, but decreased the toughness. The reversed austenite volume fraction also significantly influenced the mechanical properties.

Microstructure and Tribological Properties of AlCoCrFeNiTi0.5 High-Entropy Alloy in Hydrogen Peroxide Solution

NASA Astrophysics Data System (ADS)

Yu, Y.; Liu, W. M.; Zhang, T. B.; Li, J. S.; Wang, J.; Kou, H. C.; Li, J.

2014-01-01

Microstructure and tribological properties of an AlCoCrFeNiTi0.5 high-entropy alloy in high-concentration hydrogen peroxide solution were investigated in this work. The results show that the sigma phase precipitates and the content of bcc2 decrease during the annealing process. Meanwhile, the complex construction of the interdendrite region changes into simple isolated-island shape, and much more spherical precipitates are formed. Those changes of microstructure during the annealing process lead to the increase of hardness of this alloy. In the testing conditions, the AlCoCrFeNiTi0.5 alloy shows smoother worn surfaces and steadier coefficient of friction curves than does the 1Cr18Ni9Ti stainless steel, and SiC ceramic preserves better wear resistance than ZrO2 ceramic. After annealing, the wear resistance of the AlCoCrFeNiTi0.5 alloy increases coupled with SiC counterface but decreases with ZrO2 counterface.

Structure and photocatalytic activity studies of TiO{sub 2}-supported over Ce-modified Al-MCM-41

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishna Reddy, Jakkidi; Durgakumari, Valluri, E-mail: durgakumari@iict.res.in; Subrahmanyam, Machiraju

2009-07-01

Ce-Al-MCM-41, TiO{sub 2}/Al-MCM-41 and TiO{sub 2}/Ce-Al-MCM-41 materials with varying contents of Ce (by impregnation) and TiO{sub 2} loaded (by solid-state dispersion) on Al-MCM-41 support are prepared. The Ce modified and TiO{sub 2} loaded composite systems are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS) techniques. The DRS and XPS of low Ce content (0.2-0.5 wt.%) modified Al-MCM-41 samples are showing more characteristic of Ce{sup 3+} species wherein cerium in interaction with Al-MCM-41 and that of high Ce (0.8, 3.0 wt.%) content modified samples are showing the characteristic of bothmore » Ce{sup 4+}and Ce{sup 3+}species. A series of Ce-modified Al-MCM-41 and TiO{sub 2} loaded composite catalysts are evaluated for photocatalytic degradation of phenol under UV irradiation. Low Ce content in Ce{sup 3+} state on Al-MCM-41 is showing good photoactivity in comparison with high Ce content samples and pure ceria. The composite TiO{sub 2}/Ce-Al-MCM-41 is showing enhanced degradation activity due decreased rate of electron-hole recombination on TiO{sub 2} surface by the redox properties of cerium. The photocatalyst TiO{sub 2}/Ce-Al-MCM-41 with an optimum of 10 wt.% TiO{sub 2} and 0.3 wt.% Ce is showing maximum phenol degradation activity. The possible mechanism of phenol degradation on the composite photocatalyst is proposed.« less

Valorization of titanium metal wastes as tanning agent used in leather industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crudu, Marian, E-mail: mariancrudu@yahoo.com; Deselnicu, Viorica, E-mail: viorica.deselnicu@icpi.ro; Deselnicu, Dana Corina, E-mail: d_deselnicu@yahoo.com

2014-10-15

Highlights: • Valorization of titanium wastes which cannot be recycled in metallurgical industry. • Transferring Ti waste into raw materials for obtaining Ti based tanning agent. • Characterization of new Ti based tanning agents and leather tanned with them. • Characterization of sewage waste water and sludge resulted from leather manufacture. • Analysis of the impact of main metal component of Ti waste. - Abstract: The development of new tanning agents and new technologies in the leather sector is required to cope with the increasingly higher environmental pressure on the current tanning materials and processes such as tanning with chromiummore » salts. In this paper, the use of titanium wastes (cuttings) resulting from the process of obtaining highly pure titanium (ingots), for the synthesis of new tanning agent and tanning bovine hides with new tanning agent, as alternative to tanning with chromium salts are investigated. For this purpose, Ti waste and Ti-based tanning agent were characterized for metal content by inductively coupled plasma mass spectrometry (ICP-MS) and chemical analysis; the tanned leather (wet white leather) was characterized by Scanning Electron Microscope/Energy Dispersive Using X-ray (Analysis). SEM/EDX analysis for metal content; Differential scanning calorimetric (DSC), Micro-Hot-Table and standard shrinkage temperature showing a hydrothermal stability (ranged from 75.3 to 77 °C) and chemical analysis showing the leather is tanned and can be processed through the subsequent mechanical operations (splitting, shaving). On the other hand, an analysis of major minor trace substances from Ti-end waste (especially vanadium content) in new tanning agent and wet white leather (not detected) and residue stream was performed and showed that leachability of vanadium is acceptable. The results obtained show that new tanning agent obtained from Ti end waste can be used for tanning bovine hides, as eco-friendly alternative for chrome tanning.« less

Cotton fabrics with UV blocking properties through metal salts deposition

NASA Astrophysics Data System (ADS)

Emam, Hossam E.; Bechtold, Thomas

2015-12-01

Exposure to sunlight is important for human health as this increases the resistance to diverse pathogens, but the higher doses cause skin problems and diseases. Hence, wearing of sunlight protective fabrics displays a good solution for people working in open atmosphere. The current study offered quite simple and technically feasible ways to prepare good UV protection fabrics based on cotton. Metal salts including Zn, Cu and Ti were immobilized into cotton and oxidized cotton fabrics by using pad-dry-cure technique. Metal contents on fabrics were determined by AAS; the highest metal content was recorded for Cu-fabric and it was 360.6 mmol/kg after treatment of oxidized cotton with 0.5 M of copper nitrate. Ti contents on fabrics were ranged between 168.0 and 200.8 mmol/kg and it showed the lowest release as only 38.1-46.4% leached out fabrics after five laundry washings. Metal containing deposits were specified by scanning electron microscopy and energy dispersive X-ray spectroscopy. UV-transmission radiation over treated fabrics was measured and ultraviolet protection factor (UPF) was calculated. UPF was enhanced after treatment with Cu and Ti salts to be 11.6 and 14, respectively. After five washings, the amount of metal (Cu or Ti) retained indicates acceptable laundering durability.

Structural and light up-conversion luminescence properties of Er3+-Yb3+-W6+ substituted Bi4Ti3O12

NASA Astrophysics Data System (ADS)

Bokolia, Renuka; Rai, Vineet K.; Chauhan, Lalita; Sreenivas, K.

2016-05-01

The structural and light up-conversion (UC) luminescence properties of W6+ substituted Bi3.79Er0.03Yb0.18Ti3-xWxO12 (0 ≤ x ≤ 0.10) ceramics prepared by solid state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of single phase material with orthorhombic structure. A decrease in the lattice parameters and unit cell volume is observed with increasing W content. Strong UC luminescence at 527, 548 and 662 nm is seen under an excitation of 980 nm for an optimum W content (x = 0.06) and is attributed to the transitions 2H11/2 →4I15/2, 4S3/2 →4I15/2 and 4F9/2 →4I15/2 respectively. The improved UC luminescence is ascribed to the reduced defects such as oxygen vacancies and change in the crystal field around Er3+ ions due to B-site (Ti4+) substitution with W6+ ions. Enhanced UC emission is observed for an optimum content of w6+ in the prepared composition Bi3.79Er0.03Yb0.18Ti3-xWxO12 for x = 0.06.

Iron insertion and hematite segregation on Fe-doped TiO2 nanoparticles obtained from sol-gel and hydrothermal methods.

PubMed

Santos, Reginaldo da S; Faria, Guilherme A; Giles, Carlos; Leite, Carlos A P; Barbosa, Herbert de S; Arruda, Marco A Z; Longo, Claudia

2012-10-24

Iron-doped TiO(2) (Fe:TiO(2)) nanoparticles were synthesized by the sol-gel method (with Fe/Ti molar ratio corresponding to 1, 3, and 5%), followed by hydrothermal treatment, drying, and annealing. A similar methodology was used to synthesize TiO(2) and α-Fe(2)O(3) nanoparticles. For comparison, a mixture hematite/titania, with Fe/Ti = 4% was also investigated. Characterization of the samples using Rietveld refinement of X-ray diffraction data revealed that TiO(2) consisted of 82% anatase and 18% brookite; for Fe:TiO(2), brookite increased to 30% and hematite was also identified (0.5, 1.0, and 1.2 wt % for samples prepared with 1, 3, and 5% of Fe/Ti). For hematite/titania mixture, Fe/Ti was estimated as 4.4%, indicating the Rietveld method reliability for estimation of phase composition. Because the band gap energy, estimated as 3.2 eV for TiO(2), gradually ranged from 3.0 to 2.7 eV with increasing Fe content at Fe:TiO(2), it can be assumed that a Fe fraction was also inserted as dopant in the TiO(2) lattice. Extended X-ray absorption fine structure spectra obtained for the Ti K-edge and Fe K-edge indicated that absorbing Fe occupied a Ti site in the TiO(2) lattice, but hematite features were not observed. Hematite particles also could not be identified in the images obtained by transmission electron microscopy, in spite of iron identification by elemental mapping, suggesting that hematite can be segregated at the grain boundaries of Fe:TiO(2).

The effect of B 2O 3 addition on the crystallization of amorphous TiO 2-ZrO 2 mixed oxide

NASA Astrophysics Data System (ADS)

Mao, Dongsen; Lu, Guanzhong

2007-02-01

The effect of B 2O 3 addition on the crystallization of amorphous TiO 2-ZrO 2 mixed oxide was investigated by X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG/DTA). TiO 2-ZrO 2 mixed oxide was prepared by co-precipitation method with aqueous ammonia as the precipitation reagent. Boric acid was used as a source of boria, and boria contents varied from 2 to 20 wt%. The results indicate that the addition of small amount of boria (<8 wt%) hinders the crystallization of amorphous TiO 2-ZrO 2 into a crystalline ZrTiO 4 compound, while a larger amount of boria (⩾8 wt%) promotes the crystallization process. FT-IR spectroscopy and 11B MAS NMR results show that tetrahedral borate species predominate at low boria loading, and trigonal borate species increase with increasing boria loading. Thus it is concluded that highly dispersed tetrahedral BO 4 units delay, while a build-up of trigonal BO 3 promote, the crystallization of amorphous TiO 2-ZrO 2 to form ZrTiO 4 crystals.

Gas phase hydrogen permeation in alpha titanium and carbon steels

NASA Technical Reports Server (NTRS)

Johnson, D. L.; Shah, K. K.; Reeves, B. H.; Gadgeel, V. L.

1980-01-01

Commercially pure titanium and heats of Armco ingot iron and steels containing from 0.008-1.23 w/oC were annealed or normalized and machined into hollow cylinders. Coefficients of diffusion for alpha-Ti and alpha-Fe were determined by the lag-time technique. Steady state permeation experiments yield first power pressure dependence for alpha-Ti and Sievert's law square root dependence for Armco iron and carbon steels. As in the case of diffusion, permeation data confirm that alpha-titanium is subject to at least partial phase boundary reaction control while the steels are purely diffusion controlled. The permeation rate in steels also decreases as the carbon content increases. As a consequence of Sievert's law, the computed hydrogen solubility decreases as the carbon content increases. This decreases in explained in terms of hydrogen trapping at carbide interfaces. Oxidizing and nitriding the surfaces of alpha-titanium membranes result in a decrease in the permeation rate for such treatment on the gas inlet surfaces but resulted in a slight increase in the rate for such treatment on the gas outlet surfaces. This is explained in terms of a discontinuous TiH2 layer.

Preliminary study on the corrosion resistance, antibacterial activity and cytotoxicity of selective-laser-melted Ti6Al4V-xCu alloys.

PubMed

Guo, Sai; Lu, Yanjin; Wu, Songquan; Liu, Lingling; He, Mengjiao; Zhao, Chaoqian; Gan, Yiliang; Lin, Junjie; Luo, Jiasi; Xu, Xiongcheng; Lin, Jinxin

2017-03-01

In this study, a series of Cu-bearing Ti6Al4V-xCu (x=0, 2, 4, 6wt%) alloys (shorten by Ti6Al4V, 2C, 4C, and 6C, respectively.) with antibacterial function were successfully fabricated by selective laser melting (SLM) technology with mixed spherical powders of Cu and Ti6Al4V for the first time. In order to systematically investigate the effects of Cu content on the microstructure, phase constitution, corrosion resistance, antibacterial properties and cytotoxicity of SLMed Ti6Al4V-xCu alloys, experiments including XRD, SEM-EDS, electrochemical measurements, antibacterial tests and cytotoxicity tests were conducted with comparison to SLMed Ti6Al4V alloy (Ti6Al4V). Microstructural observations revealed that Cu had completely fused into the Ti6Al4V alloy, and presented in the form of Ti 2 Cu phase at ambient temperature. With Cu content increase, the density of the alloy gradually decreased, and micropores were obviously found in the alloy. Electrochemical measurements showed that corrosion resistance of Cu-bearing alloys were stronger than Cu-free alloy. Antibacterial tests demonstrated that 4C and 6C alloys presented strong and stable antibacterial property against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared to the Ti6Al4V and 2C alloy. In addition, similar to the Ti6Al4V alloy, the Cu-bearing alloys also exerted good cytocompatibility to the Bone Marrow Stromal Cells (BMSCs) from Sprague Dawley (SD) rats. Based on those results, the preliminary study verified that it was feasible to fabricated antibacterial Ti6Al4V-xCu alloys direct by SLM processing mixed commercial Ti6Al4V and Cu powder. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of nano-TiO2/LDPE composite film on photocatalytic oxidation degradation of dichloromethane.

PubMed

Suwannahong, Kowit; Liengcharernsit, Winai; Sanongraj, Wipada; Kruenate, Jittiporn

2012-09-01

This study focused on the photocatalytic destruction of dichloromethane (DCM) in indoor air using the nano-TiO2/LDPE composite film as an economical photocatalyst. The nano-TiO2 was dispersed in a polyethylene matrix to form composite film. The photocatalytic activity of the nano-TiO2/LDPE composite films was evaluated through the degradation of dichloromethane(DCM) under UV-C irradiance at specific wavelength of 254 nm. The percentage of nano-TiO2 contents varied from 0, 5, and 10% (wt cat./wt LDPE composite film). The results derived from the kinetic model revealed that the photocatalytic rates of 5 and 10 wt.% nano-TiO2/ LDPE composite films follow the first order reaction while the rate of the film without TiO2 followed the zero order reaction. At low concentration of DCM, the rate of photocatalytic degradation of the DCM was slower than that at high DCM concentration. The 10 wt.% of TiO2 content of the nano-TiO2/LDPE composite film yielded the highest degradation efficiency of 78%, followed by the removal efficiency of 55% for the 5 wt.% of TiO2 content of the nano-TiO2/LDPE composite film. In contrast with the composite film containing nano-TiO2, the LDPE film without adding nano-TiO2 expressed the degradation efficiency of 28%.

Synthesis, structures and magnetic properties of Pr-lean Pr2Fe14B/Fe3B nanocomposite alloys

NASA Astrophysics Data System (ADS)

Mingxiang, Pan; Pengyue, Zhang; Hongliang, Ge; Hangfu, Yang; Qiong, Wu

2012-09-01

The lean rare-earth Pr4.5Fe77-xTixB18.5 (x=0, 1, 4, 5) nanocomposite alloys were prepared by melt spinning method and subsequent thermal annealing. The effect of Ti content and annealing temperature on the magnetic properties and the microstructure of these magnets were investigated. The enhancing coercivity Hc from 211.4 to 338.2 kA/m has been observed at the optimal annealing temperature of 700 °C by the addition of 5 at% Ti in Pr2Fe14B/Fe3B alloys. It was also found that increasing Ti content leads to marked grain refinement in the annealed alloys, resulting in strong exchange-coupling interaction between the hard and the soft phases in these ribbons. In addition, the magnetization reversal behaviors of Pr2Fe14B/Fe3B nanocomposites were discussed in detail.

Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

NASA Astrophysics Data System (ADS)

Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

2018-03-01

The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

NASA Astrophysics Data System (ADS)

Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

2018-05-01

The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

Physical and absorption properties of titanium nanoparticles incorporated into zinc magnesium phosphate glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismail, S.F.; Sahar, M.R., E-mail: mrahim057@gmail.com; Ghoshal, S.K.

We report the influences of Titania (TiO{sub 2}) nanoparticles (NPs) on the physical and optical properties of melt quench synthesized zinc magnesium phosphate glasses. Five glass samples with composition (42 − x)P{sub 2}O{sub 5}–50ZnO–8MgO–xTiO{sub 2}, where x = 0, 1, 2, 3, 4 mol% are prepared and characterized. XRD pattern verified the amorphous nature of all samples. TEM images manifested the growth of Ti NPs of average size ≈ 5.78 nm. TiO{sub 2} NP concentration dependent variation in the physical properties including glass density, molar volume, molar refractivity, electronic polarizability and ionic packing density are determined. The values of glassmore » refractive indices, density and ionic packing density are increased with the increase of TiO{sub 2} NP contents. Conversely, the Urbach energy, direct and indirect optical band gap are found to decrease with the increase of TiO{sub 2} NP concentration. These glass compositions may be potential for various solid state devices including laser. - Highlights: • TiO{sub 2} NP embedded self-cleaning phosphate glass are synthesized for the first time. • Well dispersed and uniform sized TiO{sub 2} NPs are grown. • Absorption spectra revealed prominent peak in the UV region. • TiO{sub 2} NPs strongly influenced the physical and absorption features of synthesized glasses. • The effects of TiO{sub 2} NPs on the physical and optical properties of these glasses are determined.« less

Cellulose Acetate Modified Titanium Dioxide (TiO2) Nanoparticles Electrospun Composite Membranes: Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Das, Chandan; Gebru, Kibrom Alebel

2017-12-01

Hybrid membranes from Cellulose Acetate (CA) and titanium oxide (TiO2) nanoparticles were fabricated using electrospinning technique. The electrospun hybrid membranes were characterized using field emission scanning electron microscopy, high energy electrons of the energy dispersive X-ray spectroscopy, X-ray diffraction patterns, atomic force microscopy, zeta potential (ζ), and thermo gravimetric analysis. The impact of TiO2 contents on the electrospun membranes matrix was studied in detail. All these characterization results indicated that TiO2 were uniformly distributed within the CA electrospun membrane's matrix. The addition of TiO2 caused formation of largely interconnected fiber networks which in turn have a positive effect on the enhancement of the membrane pore structures. As the amount of TiO2 addition was raised from 0 to 6.5 wt%, the entanglements of the fibers and the spider-net like network among fibers were increased.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ay, H.; Özyurek, D.; Yıldırım, M., E-mail: musayildirim@karabuk.edu.tr

In this study, the wear properties of in-situ 7075 Al-Ti composites produced by powder metallurgy route were investigated. Different amount of Ti (2, 4, 6 %) added to gas atomized 7075 Al alloy powders and they were mixed in turbula with 47rpm for 45 minutes. Then the mixed powders were pre-shaped by press under 600 MPa pressure. The samples were cooled in the furnace after sintered at 580 °C for 4 hours in the atmosphere controlled furnace. Standard metallographic process such as grinding, polishing and etching were applied to sintered samples. The hardness values were measured. Scanning Electron Microscope (SEM), X-Raymore » Diffraction (XRD) examines were carried out. The wear tests were performed in a pin-on disc type wear apparatus with 1 ms{sup −1} sliding speed at six different sliding distance (500-3000 m) under 30 N loads. As a result of studies, hardness values were increased with increasing Ti content, in addition the weight losses were decreased with increasing Ti amount.« less

Electro-optical properties of low viscosity driven holographic polymer dispersed liquid crystals

NASA Astrophysics Data System (ADS)

Moon, K. R.; Bae, S. Y.; Kim, B. K.

2015-04-01

Relative diffraction efficiency (RDE), operating voltage, and response times are most important performance characteristics of holographic polymer dispersed liquid crystals (HPDLC). Two types of triallyl isocyanurate (TI) having different structures were incorporated into the conventional transmission grating of HPDLC. Premix viscosity decreased by 13-18% with up to 3% TI, beyond which it increased. TI eliminated induction period and augmented initial grating formation rate at all contents. Saturation RDE increased over 200% while threshold voltage and rise time decreased to about half and 2/3, respectively up to 3% TI, beyond which the tendencies were reversed. Among the two TIs, low viscosity monomer (TA) showed high RDE, while high miscibility monomer (TE) low characteristic voltages and short response times. It is concluded that grating formation is largely favored by low viscosity, while interface tensions and electro-optical performances by miscibility at similar viscosities.

TiO2-SiO2 Coatings with a Low Content of AuNPs for Producing Self-Cleaning Building Materials

PubMed Central

Gil, M. L. Almoraima; Mosquera, María J.

2018-01-01

The high pollution levels in our cities are producing a significant increase of dust on buildings. An application of photoactive coatings on building materials can produce buildings with self-cleaning surfaces. In this study, we have developed a simple sol-gel route for producing Au-TiO2/SiO2 photocatalysts with application on buildings. The gold nanoparticles (AuNPs) improved the TiO2 photoactivity under solar radiation because they promoted absorption in the visible range. We varied the content of AuNPs in the sols under study, in order to investigate their effect on self-cleaning properties. The sols obtained were sprayed on a common building stone, producing coatings which adhere firmly to the stone and preserve their aesthetic qualities. We studied the decolourization efficiency of the photocatalysts under study against methylene blue and against soot (a real staining agent for buildings). Finally, we established that the coating with an intermediate Au content presented the best self-cleaning performance, due to the role played by its structure and texture on its photoactivity. PMID:29558437

Interfacial reactions in titanium/SCS fiber composites during fabrication

NASA Technical Reports Server (NTRS)

Warrier, S. G.; Lin, R. Y.

1993-01-01

The objectrive of the study was to determine the effect of titanium concentration and different pyrocarbon fiber coatings on the morphology and the extent of fiber-matrix reactions in Ti/SiC composites fabricated by rapid infrared forming (RIF). It is found that the extent of fiber-matrix reactions in Ti/SiC composites fabricated by the RIF technique is noticeably affected by both an increase in Ti content and by the processing temperature. Uncoated SiC fibers extensively react with the titanium alloy matrix at 1200 C, whereas no reaction occurs when coated SiC fibers are used.

In situ stress evolution during magnetron sputtering of transition metal nitride thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abadias, G.; Guerin, Ph.

2008-09-15

Stress evolution during reactive magnetron sputtering of TiN, ZrN, and TiZrN layers was studied using real-time wafer curvature measurements. The presence of stress gradients is revealed, as the result of two kinetically competing stress generation mechanisms: atomic peening effect, inducing compressive stress, and void formation, leading to a tensile stress regime predominant at higher film thickness. No stress relaxation is detected during growth interrupt in both regimes. A change from compressive to tensile stress is evidenced with increasing film thickness, Ti content, sputtering pressure, and decreasing bias voltage.

Molecular mechanism of composite nanoparticles TiO2/WO3/GO-induced activity changes of catalase and superoxide dismutase.

PubMed

Hao, Xiaoyan; Zhang, Li; Zheng, Xin; Zong, Wansong; Liu, Chunguang

2018-06-21

More and more composite nano-photocatalysts were developed by doping, modifying and coupling, which expanded its application but resulted in pollution due to the unrecyclability. Composite photocatalyst TiO 2 /WO 3 /GO, as a model, was evaluated by exploring the molecular mechanism of TiO 2 /WO 3 /GO-induced activity changes of catalase (CAT) and superoxide dismutase (SOD). Results showed that TiO 2 /WO 3 /GO could lead to conformational and functional changes of CAT and SOD. The activity of both CAT and SOD increased depending on the exposure dose of TiO 2 /WO 3 /GO. The change skeleton structure and increase of α-helix content of CAT and SOD were certificated with UV-vis absorption and CD measurements. Intrinsic fluorescence of CAT and SOD were quenched by dynamic quenching. Micro-environment of amino acid residues of CAT and SOD became more hydrophilic, and the microenvironment of Trp residues was more vulnerable than Tyr residues with TiO 2 /WO 3 /GO exposure. In addition, inhibitory comparison between GO, TiO 2 , WO 3 and TiO 2 /WO 3 /GO was made, results showed that composite nano-photocatalyst exhibited different inhibitory compared to their parent nano-particles. Copyright © 2018. Published by Elsevier B.V.

Synthesis of titanium oxycarbonitride by carbothermal reduction and nitridation of ilmenite with recycling of polyethylene terephthalate (PET)

NASA Astrophysics Data System (ADS)

Ahmadi, Eltefat; Fauzi, Ahmad; Hussin, Hashim; Baharun, Norlia; Ariffin, Kamar Shah; Rezan, Sheikh Abdul

2017-04-01

An innovative and sustainable carbothermal reduction and nitridation (CTRN) process of ilmenite (FeTiO3) using a mixture of polyethylene terephthalate (PET) and coal as the primary reductant under an H2-N2 atmosphere was proposed. The use of PET as an alternative source of carbon not only enhances the porosity of the pellets but also results in the separation of Fe from titanium oxycarbonitride (TiO x C y N z ) particles because of the differences in surface tension. The experiments were carried out at 1250°C for 3 h using four different PET contents ranging from 25wt% to 100wt% in the reductant. X-ray diffraction (XRD), scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDX), and LECO elemental analysis were used to study the phases and microstructures of the reduced samples. In the case of 75wt% PET, iron distinctly separated from the synthesized TiO x C y N z phase. With increasing PET content in the sample, the reduction and nitridation rates substantially increased. The synthesis of an oxycarbonitride with stoichiometry of TiO0.02C0.13N0.85 with minimal intermediate titanium sub-oxides was achieved. The results also showed that the iron particles formed from CTRN of FeTiO3 exhibited a spherical morphology, which is conducive for Fe removal via the Becher process.

The effect of dietary habits on mineral composition of human scalp hair.

PubMed

Chojnacka, Katarzyna; Zielińska, Agnieszka; Michalak, Izabela; Górecki, Henryk

2010-09-01

In the present work, hair mineral analysis of 117 individuals was carried out. The subjects were asked to fill a questionnaire concerning their dietary habits. The content of minerals in hair was determined by ICP-OES (macroelements) and ICP-MS technique (micro-, toxic and other trace elements). The results were elaborated statistically by Statisticaver. 8.0. It was found that consuming highly processed food causes increased levels of e.g. Na and P in hair, intake of slimming preparation resulted in increased content of Al, Cr, Ti, taking in laxative agents caused lower level of Pb (this element was probably eliminated by other excretory routes). Individuals which declared the use of analgesic agents had more Si in their hair. Drinking coffee was related with higher level of Al, Ni, S and Ti and lower Pb in hair. Drinking tea caused reduction in the level of Hg. These results show that hair mineral content reflects exposure of elements from the diet. Copyright © 2010 Elsevier B.V. All rights reserved.

X-ray photoelectron spectroscopy characterization of composite TiO 2-poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

NASA Astrophysics Data System (ADS)

Losito, I.; Amorisco, A.; Palmisano, F.; Zambonin, P. G.

2005-02-01

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide-poly(vinylidenefluoride) (TiO 2-PVDF) films developed for applications in the photocatalytic degradation of pollutants. The composites were deposited on glass substrates by casting or spin coating from TiO 2-PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO 2-PVDF surface composition were used to optimize preparation conditions (composition of the TiO 2/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability. The use of spin-coating deposition and the increase of TiO 2 amount in the DMF suspensions were found to improve the titanium surface content, although high TiO 2/PVDF ratios led to film instability. PVDF-TiO 2 films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO 2 and the role played by the PVDF film during the degradation process.

A study on structure, morphology, optical properties, and photocatalytic ability of SrTiO3/TiO2 granular composites

NASA Astrophysics Data System (ADS)

Thi Mai Oanh, Le; Xuan Huy, Nguyen; Thi Thuy Phuong, Doan; Danh Bich, Do; Van Minh, Nguyen

2018-03-01

(1-x)SrTiO3-xTiO2 granular composites with x=0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 were synthesized by sol-gel process. Structure, morphology, optical properties, and photocatalytic activity were investigated in detail using x-ray diffraction (XRD) analysis, Raman scattering, field-emission scanning electron microscopy (FE-SEM), Transmission Electron Microscopy (TEM), ultraviolet-visible (UV-vis) absorption spectra, and photoluminescence (PL). XRD analysis showed the formation of single phase for parent phases and the present of two component phases in all composites without any impurity. A tight cohesion between TiO2 and SrTiO3 (STO) at grain boundary region was inferred from lattice parameter change of STO. Moreover, FE-SEM images revealed a granular structure of composite in which SrTiO3 particles were surrounded by smaller TiO2 nanoparticles. As TiO2 concentration increased, absorption edge firstly shifted to the left for composite with x=0.3 and then shifted gradually to the right with further increasing of TiO2 content from 30 mol% to 80 mol%. Composites exhibited a stronger photocatalytic activity than parent phases, with the highest efficiency at 50 mol% of TiO2. PL analysis result showed that the recombination rate of photogenerated electron-hole pairs decreased in composite sample, which partly explained the enhanced photocatalytic property.

Synthesis of Ag@TiO2 core-shells using a rapid microwave irradiation and study of their nonlinear optical properties

NASA Astrophysics Data System (ADS)

Karimipour, M.; Ebrahimi, M.; Abafat, Z.; Molaei, M.

2016-07-01

Ag@TiO2 core-shells were synthesized by employing oleylamine as capping agent and using a rapid microwave method. The shell growth was optimized first based on the variation of oleylamine content in the reaction solution. Thereafter the shell thickness was varied just by varying titanium isopropoxide (TiTP) with 25, 50, 100 and 200 μl as TiO2 precursor. The prepared core-shells were characterized by means of XRD, FTIR spectroscopy, transmission electron microscopy, and UV-Vis spectroscopy. XRD analysis revealed a cubic crystal structure for Ag and Anatase phase for TiO2. TEM images clearly indicated that the size of Ag core is roughly 15 nm and with the increase of TiTP, the shell thickness increases and varies between 5 nm and 15 nm. UV-Vis spectroscopy indicated that the plasmon resonance of Ag nanoparticles shifts from 407 nm up to 454 nm with the increase of TiTP precursor. Using a low power laser diode at a 532 nm wavelength, the magnitude and the sign of the nonlinear refractive index were determined by the Z-scan technique and Sheik-Bahae model. The results show that the enhancement of nonlinear optical properties originates from the quality of TiO2 shell growth. The highest nonlinearity belongs to the sample synthesized with 100 μlit TiTP. Generally all the prepared Ag@TiO2 core-shells show both saturable and reverse saturable absorption. They exhibit also a considerable nonlinear absorption and nonlinear refractive index ranging from -4.21 × 10-7 to -3.51 × 10-6 which are comparable to the sole Ag and TiO2 nanoparticles.

Low temperature oxidative desulfurization with hierarchically mesoporous titaniumsilicate Ti-SBA-2 single crystals.

PubMed

Shi, Chengxiang; Wang, Wenxuan; Liu, Ni; Xu, Xueyan; Wang, Danhong; Zhang, Minghui; Sun, Pingchuan; Chen, Tiehong

2015-07-21

Hierarchically porous Ti-SBA-2 with high framework Ti content (up to 5 wt%) was firstly synthesized by employing organic mesomorphous complexes of a cationic surfactant (CTAB) and an anionic polyelectrolyte (PAA) as templates. The material exhibited excellent performance in oxidative desulfurization of diesel fuel at low temperature (40 °C or 25 °C) due to the unique hierarchically porous structure and high framework Ti content.

Changing Seasonality of Panarctic Tundra Vegetation in Relationship to Climatic Variables

NASA Technical Reports Server (NTRS)

Bhatt, Uma S.; Walker, Donald A.; Raynolds, Martha K.; Bieniek, Peter A.; Epstein, Howard E.; Comiso, Josefino C.; Pinzon, Jorge E.; Tucker, Compton J.; Steele, Michael; Ermold, Wendy;

Antimicrobial polymers - The antibacterial effect of photoactivated nano titanium dioxide polymer composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huppmann, T., E-mail: teresa.huppmann@tum.de; Leonhardt, S., E-mail: stefan.leonhardt@mytum.de, E-mail: erhard.krampe@tum.de; Krampe, E., E-mail: stefan.leonhardt@mytum.de, E-mail: erhard.krampe@tum.de

To obtain a polymer with antimicrobial properties for medical and sanitary applications nanoscale titanium dioxide (TiO{sub 2}) particles have been incorporated into a medical grade polypropylene (PP) matrix with various filler contents (0 wt %, 2 wt %, 10 wt % and 15 wt %). The standard application of TiO{sub 2} for antimicrobial efficacy is to deposit a thin TiO{sub 2} coating on the surface. In contrast to the common way of applying a coating, TiO{sub 2} particles were applied into the bulk polymer. With this design we want to ensure antimicrobial properties even after application of impact effects thatmore » could lead to surface defects. The filler material (Aeroxide® TiO{sub 2} P25, Evonik) was applied via melt compounding and the compounding parameters were optimized with respect to nanoscale titanium dioxide. In a next step the effect of UV-irradiation on the compounds concerning their photocatalytic activity, which is related to the titanium dioxide amount, was investigated. The photocatalytic effect of TiO{sub 2}-PP-composites was analyzed by contact angle measurement, by methylene blue testing and by evaluation of inactivation potential for Escherichia coli (E.coli) bacteria. The dependence of antimicrobial activity on the filler content was evaluated, and on the basis of different titanium dioxide fractions adequate amounts of additives within the compounds were discussed. Specimens displayed a higher photocatalytic and also antimicrobial activity and lower contact angles with increasing titania content. The results suggest that the presence of titania embedded in the PP matrix leads to a surface change and a photocatalytic effect with bacteria killing result.« less

Mg-containing hydroxyapatite coatings on Ti-6Al-4V alloy for dental materials

NASA Astrophysics Data System (ADS)

Yu, Ji-Min; Choe, Han-Cheol

2018-02-01

In this study, Mg-containing hydroxyapatite coatings on Ti-6A1-4 V alloy for dental materials were researched using various experimental instruments. Plasma electrolytic oxidation (PEO) was performed in electrolytes containing Mg (symbols of specimens: CaP, 5M%, 10M%, and 20M%) at 280 V for 3 min. The electrolyte used for PEO was produced by mixing Ca(CH3COO)2·H2O, C3H7NaCaO6P, and MgCl2·6H2O. The phases and composition of the oxide films were evaluated by X-ray diffraction and field-emission scanning electron microscopy with energy dispersive X-ray spectrometry. The irregularity of the surface, pore size, and number of pores decreased as the Mg concentration increased. The ratio of the areas occupied and not occupied by pores decreased as the Mg concentration increased, with the numbers of both large and small pores decreasing with increasing Mg concentration. The number of particles on the internal surfaces of pores was increased as the Mg content increased. Mg content of all samples containing Mg ions showed higher in the pore outside than that of pore inside, whereas the Ca content was higher inside the pores. The P content of samples with the addition of Mg ions showed higher values inside the pores than outside. The Ca/P and [Mg + Ca]/P molar ratios in the PEO films decreased with Mg content. The crystallite size of anatase was increased with increasing Mg concentration in the solution.

Magnetic properties of mixed spinel BaTiO{sub 3}-NiFe{sub 2}O{sub 4} composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal

2014-03-28

Solid solution of nickel ferrite (NiFe{sub 2}O{sub 4}) and barium titanate (BaTiO{sub 3}), (100-x)BaTiO{sub 3}–(x) NiFe{sub 2}O{sub 4} has been prepared by solid state reaction. Compressive strain is developed in NiFe{sub 2}O{sub 4} due to mutual structural interaction across the interface of NiFe{sub 2}O{sub 4} and BaTiO{sub 3} phases. Quantitative analysis of X-ray diffraction and X-ray photo electron spectrum suggest mixed spinel structure of NiFe{sub 2}O{sub 4}. A systematic study of composition dependence of composite indicates BaTiO{sub 3} causes a random distribution of Fe and Ni cations among octahedral and tetrahedral sites during non-equilibrium growth of NiFe{sub 2}O{sub 4}. Themore » degree of inversion decreases monotonically from 0.97 to 0.75 with increase of BaTiO{sub 3} content. Temperature dependence of magnetization has been analyzed by four sublattice model to describe complex magnetic exchange interactions in mixed spinel phase. Curie temperature and saturation magnetization decrease with increase of BaTiO{sub 3} concentration. Enhancement of strain and larger occupancy of Ni{sup 2+} at tetrahedral site increase coercivity up to 200 Oe. Magnetostructual coupling induced by BaTiO{sub 3} improves coercivity in NiFe{sub 2}O{sub 4}. An increase in the demagnetization and homogeneity in magnetization process in NiFe{sub 2}O{sub 4} is observed due to the interaction with diamagnetic BaTiO{sub 3}.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rani, Jyoti; Yadav, K.L., E-mail: klyadav35@yahoo.com; Prakash, Satya

Highlights: • Spinel–perovskite xCoFe{sub 2}O{sub 4}–(1 − x)(0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}) composites have been synthesized by solid state reaction method. • Two anomalies in dielectric constant have been identified, and the composites show relaxor behaviour. • The magnetic properties of the composites improve with increasing concentration of CoFe{sub 2}O{sub 4}. • Enhanced magnetodielectric effect is found, and magnetoelectric coupling has been confirmed by Δϵ ∼ γM{sup 2} relation. • Optical band gap energy of these composites has been reported for the first time. - Abstract: xCoFe{sub 2}O{sub 4}–(1 − x)(0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}) compositesmore » with x = 0.1, 0.2, 0.3 and 0.4 have been synthesized by solid state reaction method. X-ray diffraction analysis and field emission secondary electron microscopy have been used for structural and morphological analysis, respectively. The spinel CoFe{sub 2}O{sub 4} and perovskite 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} phase could be identified in the composites. Two anomalies in dielectric constant have been identified: first one is close to ferroelectric to paraelectric phase transition of 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} ceramic and the other lies near the magnetic transition temperature of CoFe{sub 2}O{sub 4}. There is an increase in magnetocapacitance and saturation magnetization of the composites at room temperature with increase in CoFe{sub 2}O{sub 4} content. The magnetoelectric coupling coefficient (γ) was approximated by Δϵ ∼ γM{sup 2} relation. The optical band gap energy of the composites decreases with increase in CoFe{sub 2}O{sub 4} content.« less

Effect of sulfur content on the microstructure and toughness of simulated heat-affected zone in Ti-killed steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jyelong Lee; Yeongtsuen Pan

1993-06-01

Four Ti-killed steels were made to study the specific influence of sulfur on the inclusion, microstructure, and toughness of a simulated heat-affected zone (HAZ). The HAZ toughness was mainly determined by the volume fraction of intragranular acicular ferrite (IAF) which was closely related to the supercooling required to initiate austenite to ferrite transformation. The extent of supercooling was strongly influenced by the composition of grain boundary and inclusions. Sulfur addition up to 102 ppm caused a segregation of sulfur to the grain boundaries and a change of inclusion phase from predominantly Ti-oxides to Ti-oxysulphides and MnS. This behavior, in turn,more » suppressed the formation of IAF polygonal ferrite and promoted the formation of IAF. Further addition of sulfur elevated transformation temperature and promoted the formation of polygonal ferrite due to the refinement of grain size and the increase of grain boundary associated inclusions. A methodology was proposed to evaluate the intragranular nucleation potential of inclusions, and the results showed that Ti-oxysulphides possessed better nucleation potential for IAF than Ti-oxides and MnS. With the lowest transformation temperature and most effective nuclei, the best HAZ toughness can be obtained at sulfur content of 102 ppm due to the achievement of the maximum volume fraction of IAF.« less

Elevated temperature slow plastic deformation of NiAl/TiB2 particulate composites

NASA Technical Reports Server (NTRS)

Whittenberger, J. Daniel; Mannan, S. K.; Sprissler, B.; Viswanadham, R. K.

1988-01-01

The 'XD' process for production of discontinuously-reinforced metal-matrix composites has been used to enhance the high-temperature strength of NiAl-TiB2 composites with particulate densities of up to 30 vol pct. SEM, TEM, and optical characterizations of the resulting microstructures showed the average TiB2 particle size to be about 1 micron, while the average grain of the NiAl matrix was of the order of 10 microns. Elevated temperature compression tests conducted at 1200 and 1300 K indicated flow strengths to increase with TiB2 content, so that the 20 vol pct TiB2-reinforced composite was three times stronger than the unreinforced NiAl; this is ascribed to the very high density of microstructural tangled dislocations, loops, and subgrain boundaries connecting the particles.

Waste conversion into high-value ceramics: Carbothermal nitridation synthesis of titanium nitride nanoparticles using automotive shredder waste.

PubMed

Mayyas, Mohannad; Pahlevani, Farshid; Maroufi, Samane; Liu, Zhao; Sahajwalla, Veena

2017-03-01

Environmental concern about automotive shredder residue (ASR) has increased in recent years due to its harmful content of heavy metals. Although several approaches of ASR management have been suggested, these approaches remain commercially unproven. This study presents an alternative approach for ASR management where advanced materials can be generated as a by-product. In this approach, titanium nitride (TiN) has been thermally synthesized by nitriding pressed mixture of automotive shredder residue (ASR) and titanium oxide (TiO 2 ). Interactions between TiO 2 and ASR at non-isothermal conditions were primarily investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry. Results indicated that TiO 2 influences and catalyses degradation reactions of ASR, and the temperature, at which reduction starts, was determined around 980 °C. The interaction between TiO 2 and ASR at isothermal conditions in the temperature range between 1200 and 1550 °C was also studied. The pressed mixture of both materials resulted in titanium nitride (TiN) ceramic at all given temperatures. Formation kinetics were extracted using several models for product layer diffusion-controlled solid-solid and solid-fluid reactions. The effect of reactants ratio and temperature on the degree of conversion and morphology was investigated. The effect of reactants ratio was found to have considerable effect on the morphology of the resulting material, while temperature had a lesser impact. Several unique structures of TiN (porous nanostructured, polycrystalline, micro-spherical and nano-sized structures) were obtained by simply tuning the ratio of TiO 2 to ASR, and a product with appreciable TiN content of around 85% was achieved after only one hour nitridation at 1550 °C. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ferroelectric Properties of La Substituted PZT Ceramics

NASA Astrophysics Data System (ADS)

Rani, Rekha; Juneja, J. K.; Raina, K. K.; Prakash, Chandra

2011-11-01

For the present study, La substituted PZT ceramics having compositional formula Pb1-3x/2LaxZr0.65Ti0.35O3 were prepared by conventional solid state method. La content was varied from x = 0 to 0.03 in the steps of 0.01. XRD analyses of all the samples were done and were found to have single phase with rhombohedral structure. In this paper, we are reporting the variation in ferroelectric properties of Pb1-3x/2LaxZr0.65Ti0.35O3 by varying La content. P-E hysteresis loops were recorded using P-E loop tracer based on Sawyer- Tower circuit for all the samples at 20 Hz. Increase in coercive field (Ec), remanant polarization (Pr), saturation polarization (Ps) and squareness ratio (Pr/Ps) was observed with increase in x.

TiO2 nanoparticle-induced ROS correlates with modulated immune cell function

NASA Astrophysics Data System (ADS)

Maurer-Jones, Melissa A.; Christenson, Jenna R.; Haynes, Christy L.

2012-12-01

Design of non-toxic nanoparticles will be greatly facilitated by understanding the nanoparticle-cell interaction mechanism on a cell function level. Mast cells are important cells for the immune system's first line of defense, and we can utilize their exocytotic behavior as a model cellular function as it is a conserved process across cell types and species. Perturbations in exocytosis can also have implications for whole organism health. One proposed mode of toxicity is nanoparticle-induced reactive oxygen species (ROS), particularly for titanium dioxide (TiO2) nanoparticles. Herein, we have correlated changes in ROS with the perturbation of the critical cell function of exocytosis, using UV light to induce greater levels of ROS in TiO2 exposed cells. The primary culture mouse peritoneal mast cells (MPMCs) were exposed to varying concentrations of TiO2 nanoparticles for 24 h. ROS content was determined using 2,7-dihydrodichlorofluorescein diacetate (DCFDA). Cellular viability was determined with the MTT and Trypan blue assays, and exocytosis was measured by the analytical electrochemistry technique of carbon-fiber microelectrode amperometry. MPMCs exposed to TiO2 nanoparticles experienced a dose-dependent increase in total ROS content. While there was minimal impact of ROS on cellular viability, there is a correlation between ROS amount and exocytosis perturbation. As nanoparticle-induced ROS increases, there is a significant decrease (45 %) in the number of serotonin molecules being released during exocytosis, increase (26 %) in the amount of time for each exocytotic granule to release, and decrease (28 %) in the efficiency of granule trafficking and docking. This is the first evidence that nanoparticle-induced ROS correlates with chemical messenger molecule secretion, possibly making a critical connection between functional impairment and mechanisms contributing to that impairment.

Powder metallurgical low-modulus Ti-Mg alloys for biomedical applications.

PubMed

Liu, Yong; Li, Kaiyang; Luo, Tao; Song, Min; Wu, Hong; Xiao, Jian; Tan, Yanni; Cheng, Ming; Chen, Bing; Niu, Xinrui; Hu, Rong; Li, Xiaohui; Tang, Huiping

2015-11-01

In this work, powder metallurgical (PM) Ti-Mg alloys were prepared using combined techniques of mechanical alloying and spark plasma sintering. The alloys mainly consist of super saturations of Mg in Ti matrix, and some laminar structured Ti- and Mg-rich phases. The PM Ti-Mg alloys contain a homogeneous mixtures of nanocrystalline Mg and Ti phases. The novel microstructures result in unconventional mechanical and biological properties. It has been shown that the PM Ti-Mg alloys have a much lower compression modulus (36-50GPa) compared to other Ti alloys, but still remain a very high compressive strength (1500-1800MPa). In addition, the PM Ti-Mg alloys show good biocompatibility and bioactivity. Mg can dissolve in the simulated body fluids, and induce the formation of the calcium phosphate layer. The compression modulus of PM Ti-Mg alloys decreases with the amount of Mg, while the bioactivity increases. Although the corrosion resistance of Ti-Mg alloys decreases with the content of Mg, the alloys still show good stability in simulated body fluid under electrochemical conditions. The indirect and direct cytotoxicity results show that PM Ti-Mg alloys have a good biocompatibility to NIH-3T3 cells. Therefore, the PM Ti-Mg alloys are promising candidates in biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

A hydrothermal peroxo method for preparation of highly crystalline silica-titania photocatalysts.

PubMed

Krivtsov, Igor; Ilkaeva, Marina; Avdin, Viacheslav; Khainakov, Sergei; Garcìa, Jose R; Ordòñez, Salvador; Dìaz, Eva; Faba, Laura

2015-04-15

A new completely inorganic method of preparation of silica-titania photocatalyst has been described. It has been established that the addition of silica promotes crystallinity of TiO2 anatase phase. Relative crystallinity and TiO2 crystal size in the silica-titania particles increase with the silica content until SiO2/TiO2 molar ratio of 0.9, but at higher molar ratios they start to decrease. The single-source precursor containing peroxo titanic (PTA) and silicic acids has been proved to be responsible for high crystallinity of TiO2 encapsulated into amorphous silica. It has been proposed that peroxo groups enhance rapid formation of crystalline titania seeds, while silica controls their growth. It has been concluded from the TEM that the most morphologically uniform anatase crystallites covered with SiO2 particles are prepared at SiO2/TiO2 molar ratio of 0.4. This sample, according to (29)Si NMR, also shows the high content of hydroxylated silica Q(3) and Q(2) groups, and it is the most photocatalytically active in UV-assisted decomposition of methylene blue among the tested materials. It has been determined that the increase in the amount of the condensed Q(4) silica in the mixed oxides leads to the decrease in photocatalytic performance of the material, despite its better crystallinity. High crystallinity, low degree of incorporation of Ti atoms in SiO2 in the mixed oxide and adsorption of methylene blue in the vicinity of photoactive sites on the hydroxylated silica have been considered as the main factors determining the high degradation degree of methylene blue in the presence of silica-titania. Copyright © 2014 Elsevier Inc. All rights reserved.

Preparation of highly ordered mesoporous Al2O3/TiO2 and its application in dye-sensitized solar cells.

PubMed

Kim, Jae-Yup; Kang, Soon Hyung; Kim, Hyun Sik; Sung, Yung-Eun

2010-02-16

Highly ordered mesoporous Al(2)O(3)/TiO(2) was prepared by sol-gel reaction and evaporation-induced self-assembly (EISA) for use in dye-sensitized solar cells. The prepared materials had two-dimensional, hexagonal pore structures with anatase crystalline phases. The average pore size of mesoporous Al(2)O(3)/TiO(2) remained uniform and in the range of 6.33-6.58 nm while the Brunauer-Emmett-Teller (BET) surface area varied from 181 to 212 m(2)/g with increasing the content of Al(2)O(3). The incorporation of Al content retarded crystallite growth, thereby decreasing crystallite size while simultaneously improving the uniformity of pore size and volume. The thin Al(2)O(3) layer was located mostly on the mesopore surface, as confirmed by X-ray photoelectron spectroscopy (XPS). The Al(2)O(3) coating on the mesoporous TiO(2) film contributes to the essential energy barrier which blocks the charge recombination process in dye-sensitized solar cells. Mesoporous Al(2)O(3)/TiO(2) (1 mol % Al(2)O(3)) exhibited enhanced power conversion efficiency (V(oc) = 0.74 V, J(sc) = 15.31 mA/cm(2), fill factor = 57%, efficiency = 6.50%) compared to pure mesoporous TiO(2) (V(oc) = 0.72 V, J(sc) = 16.03 mA/cm(2), fill factor = 51%, efficiency = 5.88%). Therefore, the power conversion efficiency was improved by approximately 10.5%. In particular, the increase in V(oc) and fill factor resulted from the inhibition of charge recombination and the improvement of pore structure.

Microstructure and mechanical properties of the NiNbZrTiAl amorphous alloys with 10 and 25 at.% Nb content.

PubMed

Czeppe, T; Ochin, P; Sypień, A; Major, L

2010-03-01

The results of investigation of two different Ni-based glasses with compositions Ni(58)Nb(10)Zr(13)Ti(12)Al(7) and Ni(58)Nb(25)Zr(8)Ti(6)Al(3) are presented. The structure of the melt spun ribbons was amorphous. The supercooled liquid range decreased and primary crystallization temperature increased with increasing Nb content while the parameter T(g)/T(m) slightly increased. The crystallization process proceeded in a different way. The ribbon containing 10 at.% Nb showed typical primary crystallization of the 50 nm grains of the NiTi(Nb) cubic phase; the ribbon containing 25 at.% of Nb revealed high thermal stability of the amorphous phase, which crystallized only in a small amount in the range of primary crystallization, preserving large fraction of the amorphous phase even high above the end of the crystallization. The tensile load-displacement curves were also different. In both cases, the ribbons revealed quite a large range of the plastic elongation. The ribbon containing 10% Nb showed stress relaxation and was maximally elongated up to 0.6. The ribbon with 25 at.% Nb revealed a hardening effect and the slightly smaller maximal elongation following it. The microstructure of the deformed specimens showed deformation bands parallel to the tensile axis, microcracks formation along shear bands and river-like pattern at the fracture surfaces. In both cases, high resolution electron microscope did not reveal any crystallization after deformation.

Influence of Deformation Mechanisms on the Mechanical Behavior of Metals and Alloys: Experiments, Constitutive Modeling, and Validation

NASA Astrophysics Data System (ADS)

Gray, G. T.; Cerreta, E.; Chen, Shuh Rong; Maudlin, P. J.

2004-06-01

Jim Williams has made seminal contributions to the field of structure / property relations and its controlling effects on the mechanical behavior of metals and alloys. This talk will discuss experimental results illustrating the role of interstitial content, grain size, texture, temperature, and strain rate on the operative deformation mechanisms, mechanical behavior, and substructure evolution in titanium, zirconium, hafnium, and rhenium. Increasing grain size is shown to significantly decrease the dynamic flow strength of Ti and Zr while increasing work-hardening rates due to an increased incidence of deformation twinning. Increasing oxygen interstitial content is shown to significantly alter both the constitutive response and α-ω shock-induced phase transition in Zr. The influence of crystallographic texture on the mechanical behavior in Ti, Zr, and Hf is discussed in terms of slip system and deformation twinning activity. An example of the utility of incorporation of operative deformation mechanisms into a polycrystalline plasticity constitutive model and validation using Taylor cylinder impact testing is presented.

Investigating compositional effects of atomic layer deposition ternary dielectric Ti-Al-O on metal-insulator-semiconductor heterojunction capacitor structure for gate insulation of InAlN/GaN and AlGaN/GaN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colon, Albert; Stan, Liliana; Divan, Ralu

Gate insulation/surface passivation in AlGaN/GaN and InAlN/GaN heterojunction field-effect transistors is a major concern for passivation of surface traps and reduction of gate leakage current. However, finding the most appropriate gate dielectric materials is challenging and often involves a compromise of the required properties such as dielectric constant, conduction/valence band-offsets, or thermal stability. Creating a ternary compound such as Ti-Al-O and tailoring its composition may result in a reasonably good gate material in terms of the said properties. To date, there is limited knowledge of the performance of ternary dielectric compounds on AlGaN/GaN and even less on InAlN/GaN. To approachmore » this problem, the authors fabricated metal-insulator-semiconductor heterojunction (MISH) capacitors with ternary dielectrics Ti-Al-O of various compositions, deposited by atomic layer deposition (ALD). The film deposition was achieved by alternating cycles of TiO2 and Al2O3 using different ratios of ALD cycles. TiO2 was also deposited as a reference sample. The electrical characterization of the MISH capacitors shows an overall better performance of ternary compounds compared to the pure TiO2. The gate leakage current density decreases with increasing Al content, being similar to 2-3 orders of magnitude lower for a TiO2:Al2O3 cycle ratio of 2:1. Although the dielectric constant has the highest value of 79 for TiO2 and decreases with increasing the number of Al2O3 cycles, it is maintaining a relatively high value compared to an Al2O3 film. Capacitance voltage sweeps were also measured in order to characterize the interface trap density. A decreasing trend in the interface trap density was found while increasing Al content in the film. In conclusion, our study reveals that the desired high-kappa properties of TiO2 can be adequately maintained while improving other insulator performance factors. The ternary compounds may be an excellent choice as a gate material for both AlGaN/GaN and InAlN/GaN based devices.« less

Photo degradation of methyl orange by attapulgite-SnO2-TiO2 nanocomposites.

PubMed

Zhang, Lili; Lv, Fujian; Zhang, Weiguang; Li, Rongqing; Zhong, Hui; Zhao, Yijiang; Zhang, Yu; Wang, Xin

2009-11-15

Photocatalytic removal of methyl orange under ultraviolet radiation has been studied using attapulgite (ATT) composites, which were synthesized by depositing SnO(2)-TiO(2) hybrid oxides on the surface of ATT to form a composite photocatalyst (denoted ATT-SnO(2)-TiO(2)) using an in situ sol-gel technique. Results showed that SnO(2)-TiO(2) nanocomposite particles with average size of about 10nm were loaded successfully on to the surface of ATT fibers and were widely dispersed. Correspondingly, the photocatalytic activity of ATT was improved significantly by loading SnO(2)-TiO(2). The photoactivity of the composite photocatalyst decreased in the sequence ATT-SnO(2)-TiO(2)>ATT-SnO(2)>ATT-TiO(2)>ATT. In order to achieve the best photocatalyst, the molar ratio of SnO(2) and TiO(2) in the ATT-SnO(2)-TiO(2) composites was adjusted to give a series with proportions r=n(Ti)/(n(Ti)+n(Sn))=0.0, 0.25, 0.33, 0.50, 0.67, 0.75, 0.80, 0.82, 0.86, 1.0. Results indicated that the proportion of SnO(2) and TiO(2) had a critical effect on the photocatalytic activity, which increased as the content of TiO(2) increased to r0.82. The highest degradation rate of methyl orange was 99% within 30 min obtained by using ATT-SnO(2)-TiO(2) with r=0.82. The repeated use of the composite photocatalyst was also confirmed.

Petrogenesis of mare basalts - A record of lunar volcanism

NASA Astrophysics Data System (ADS)

Neal, Clive R.; Taylor, Lawrence A.

1992-06-01

The classification, sources, and overall petrogenesis of mare basalts are reviewed. All mare basalt analyses are used to define a sixfold classification scheme using TiO2 contents as the primary division. A secondary division is made using Al2O3 contents, and a tertiary division is defined using K contents. Such divisions and subdivisions yield a classification containing 12 categories, of which six are accounted for by the existing Apollo and Luna collections. A variety of postmagma-generation such as fractional crystallization, either alone or combined with wallrock assimilation, are invoked to explain the compositional ranges of the various mare basalt suites. High-Ti mare basalts are found at Apollo 1 and Apollo 17 sites; the A-11 basalts contain lower TiO2 abundances, a considerably larger range in trace-element contents, and the only occurrence of high-Ti/high-K mare basalts. The low-Ti basalts exhibit a wide range of major-and trace-element compositions and require source heterogeneity, fractional crystallization, and some assimilation.

Hydrogen sorption and permeability of compacted LiBH4 nanoconfined into activated carbon nanofibers impregnated with TiO2

NASA Astrophysics Data System (ADS)

Sitthiwet, Chongsutthamani; Thiangviriya, Sophida; Thaweelap, Natthaporn; Meethom, Sukanya; Kaewsuwan, Dechmongkhon; Chanlek, Narong; Utke, Rapee

2017-11-01

Activated carbon nanofibers impregnated with titanium (IV) oxide (TiO2), denoted as ACNF-Ti are prepared by carbonization and activation of electrospun nanofibers of polyacrylonitrile (PAN)-titanium (IV) isopropoxide composite. Pristine LiBH4 and nanoconfined LiBH4 in ACNF-Ti, denoted as LiBH4-ACNF-Ti are compacted under the pressures of 434 and 868 MPa. Dehydrogenation temperature of compacted LiBH4 increases (up to 485 °C) with compaction pressure due to poor hydrogen permeability. In the case of compacted LiBH4-ACNF-Ti, major dehydrogenation temperature at 352-359 °C and hydrogen content liberated (74-76% of theoretical capacity) are obtained despite enhanced compaction pressure. Mechanical stability during cycling of compacted LiBH4-ACNF-Ti is achieved. Although hydrogen permeability of compacted LiBH4-ACNF-Ti improves with enhanced compaction pressure, detrimental kinetics and reversibility are detected. Since the fibrous structure of ACNF-Ti are brittle, the broken and/or shorten fibers are observed after compaction under high pressure. The latter results in not only inferior nanoconfinement of LiBH4 into ACNF-Ti, but also agglomeration of hydride materials upon cycling.

Characterization and activity of Pd-modified TiO2 catalysts for photocatalytic oxidation of NO in gas phase.

PubMed

Wu, Zhongbiao; Sheng, Zhongyi; Liu, Yue; Wang, Haiqiang; Tang, Nian; Wang, Jie

2009-05-30

Pd-modified TiO(2) prepared by thermal impregnation method was used in this study for photocatalytic oxidation of NO in gas phase. The physico-chemical properties of Pd/TiO(2) catalysts were characterized by X-ray diffraction analysis (XRD), Brunauer-Emmett-Teller measurements (BET), X-ray photoelectron spectrum analysis (XPS), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), UV-vis diffuse reflectance spectra (UV-vis DRS) and photoluminescence spectra (PL). It was found that Pd dopant existed as PdO particles in as-prepared photocatalysts. The results of PL spectra indicated that the photogenerated electrons and holes were efficiently separated after Pd doping. During in situ XPS study, it was found that the content of hydroxyl groups on the surface of Pd/TiO(2) increased when the catalyst was irradiated by UV light, which could result in the improvement of photocatalytic activity. The activity test showed that the optimum Pd dopant content was 0.05 wt.%. And the maximum conversion of NO was about 72% higher than that of P25 when the initial concentration of NO was 200 ppm, which showed that Pd/TiO(2) photocatalysts could be potentially applied to oxidize higher concentration of NO.

Hertzian indentation of colloidally processed titanium carbide-nickel aluminide composites

NASA Astrophysics Data System (ADS)

Collier, R. Bradley

Advanced cermets based on titanium carbide (TiC), with a ductile nickel aluminide (Ni3Al) binder, have shown significant promise for use in a variety of demanding wear environments, due to a combination of high strength and good corrosion behaviour. A unique feature of TiC-Ni3Al cermets is that they show increasing strength from room temperature up to ˜1,000°C, while current materials such as tungsten carbide/cobalt (WC/Co) show significant strength degradation above ˜500°C. In this thesis, aqueous colloidal forming methods have been applied to process TiC preforms. The mechanisms and effectiveness of suspension stabilization were examined using methods such as zeta potential analysis, rheological measurements, and sedimentation trials for two common dispersants; an ammonium salt of polymethacrylate (PMA-NH 4) and two molecular weights (l,800 and 10,000) of polyethylenimine (PEI). TiC preforms were prepared by slip casting suspensions of up to 50 vol. % solids content. After drying, the TiC-based cermets were processed by melt infiltration with the Ni3Al alloy (IC-50) at 1475°C.Ni 3Al content was varied between 20 and 50 vol. % using this approach, resulting in final densities that exceeded 98% of theoretical. These samples were subjected to Hertzian indentation testing with loads ranging from 250 -- 2000 N, using WC-Co spheres with sizes ranging from 1.191 to 2.38 mm. Indentation stress-strain curves were produced from the indentation data and compared to the calculated elastic Hertzian response. The bonded interface method was used to examine the subsurface deformation of the material under load. Significant deformation of the binder and the eventual fracture of the TiC grains were observed. The nature of the quasi-plasticity of TiC-Ni 3Al and the effects of binder content on surface and subsurface deformation is examined.

Electrical and magnetic properties of La0.67Ba0.33Mn1- x (Me) x O3 perovskite manganites: case of manganese substituted by trivalent (Me = Cr) and tetravalent (Me = Ti) elements

NASA Astrophysics Data System (ADS)

Oumezzine, Marwène; Peña, Octavio; Kallel, Sami; Kallel, Nabil; Guizouarn, Thierry; Gouttefangeas, Francis; Oumezzine, Mohamed

2014-03-01

The effects of non-magnetic Ti4+ substitution on the structural, electrical and magnetic properties of La0.67Ba0.33Mn1- x Ti x O3 (0≤ x≤0.1) are investigated and compared to those existing in La0.67Ba0.33Mn1- x Cr x O3 (magnetic Cr3+). The structural refinement by the Rietveld method revealed that Ti-doped samples crystallize in the cubic lattice with space group , while samples with Cr crystallize in the hexagonal setting of the rhombohedral space group for identical contents of dopant. The most relevant structural features are an increase of the lattice parameters, of the cell volume and of the inter-ionic distances with increasing Ti doping level. Both series of samples show a decrease of the paramagnetic-ferromagnetic transition temperature when the amount of chromium or titanium increases. Transport measurements show that when increasing the metal doping, the resistivity increases whereas the metallic behavior of the parent compound La0.67Ba0.33MnO3 is destroyed. For a substitution higher than 5 at.% of Ti and 10 at.% of Cr, the samples exhibit a semiconducting behavior in the whole range of temperature, for which the electronic transport can be explained by variable range hopping and/or small polaron hopping models.

Electronic structures of anatase (TiO2)1-x(TaON)x solid solutions: a first-principles study.

PubMed

Dang, Wenqiang; Chen, Hungru; Umezawa, Naoto; Zhang, Junying

2015-07-21

Sensitizing wide band gap photo-functional materials under visible-light irradiation is an important task for efficient solar energy conversion. Although nitrogen doping into anatase TiO2 has been extensively studied for this purpose, it is hard to increase the nitrogen content in anatase TiO2 because of the aliovalent nitrogen substituted for oxygen, leading to the formation of secondary phases or defects that hamper the migration of photoexcited charge carriers. In this paper, electronic structures of (TiO2)1-x(TaON)x (0 ≤ x ≤ 1) solid solutions, in which the stoichiometry is satisfied with the co-substitution of Ti for Ta along with O for N, are investigated within the anatase crystal structure using first-principles calculations. Our computational results show that the solid solutions have substantially narrower band gaps than TiO2, without introducing any localized energy states in the forbidden gap. In addition, in comparison with the pristine TiO2, the solid solution has a direct band gap when the content of TaON exceeds 0.25, which is advantageous to light absorption. The valence band maximum (VBM) of the solid solutions, which is mainly composed of N 2p states hybridized with O 2p, Ti 3d or Ta 5d orbitals, is higher in energy than that of pristine anatase TiO2 consisting of non-bonding O 2p states. On the other hand, incorporating TaON into TiO2 causes the formation of d-d bonding states through π interactions and substantially lowers the conduction band minimum (CBM) because of the shortened distance between some metal atoms. As a result, the anatase (TiO2)1-x(TaON)x is expected to become a promising visible-light absorber. In addition, some atomic configurations are found to possess exceptionally narrow band gaps.

Designing the Color of Hot-Dip Galvanized Steel Sheet Through Destructive Light Interference Using a Zn-Ti Liquid Metallic Bath

NASA Astrophysics Data System (ADS)

Levai, Gabor; Godzsák, Melinda; Török, Tamas I.; Hakl, Jozsef; Takáts, Viktor; Csik, Attila; Vad, Kalman; Kaptay, George

2016-07-01

The color of hot-dip galvanized steel sheet was adjusted in a reproducible way using a liquid Zn-Ti metallic bath, air atmosphere, and controlling the bath temperature as the only experimental parameter. Coloring was found only for samples cooled in air and dipped into Ti-containing liquid Zn. For samples dipped into a 0.15 wt pct Ti-containing Zn bath, the color remained metallic (gray) below a 792 K (519 °C) bath temperature; it was yellow at 814 K ± 22 K (541 °C ± 22 °C), violet at 847 K ± 10 K (574 °C ± 10 °C), and blue at 873 K ± 15 K (600 °C ± 15 °C). With the increasing bath temperature, the thickness of the adhered Zn-Ti layer gradually decreased from 52 to 32 micrometers, while the thickness of the outer TiO2 layer gradually increased from 24 to 69 nm. Due to small Al contamination of the Zn bath, a thin (around 2 nm) alumina-rich layer is found between the outer TiO2 layer and the inner macroscopic Zn layer. It is proven that the color change was governed by the formation of thin outer TiO2 layer; different colors appear depending on the thickness of this layer, mostly due to the destructive interference of visible light on this transparent nano-layer. A complex model was built to explain the results using known relationships of chemical thermodynamics, adhesion, heat flow, kinetics of chemical reactions, diffusion, and optics. The complex model was able to reproduce the observations and allowed making predictions on the color of the hot-dip galvanized steel sample, as a function of the following experimental parameters: temperature and Ti content of the Zn bath, oxygen content, pressure, temperature and flow rate of the cooling gas, dimensions of the steel sheet, velocity of dipping the steel sheet into the Zn-Ti bath, residence time of the steel sheet within the bath, and the velocity of its removal from the bath. These relationships will be valuable for planning further experiments and technologies on color hot-dip galvanization of steel by Zn-Ti alloys.

Thermoelectric Properties of Dy-Doped SrTiO3 Ceramics

NASA Astrophysics Data System (ADS)

Liu, J.; Wang, C. L.; Peng, H.; Su, W. B.; Wang, H. C.; Li, J. C.; Zhang, J. L.; Mei, L. M.

2012-11-01

Sr1- x Dy x TiO3 ( x = 0.02, 0.05, 0.10) ceramics were prepared by the reduced solid-state reaction method, and their thermoelectric properties were investigated from room temperature to 973 K. The resistivity increases with temperature, showing metallic behavior. The Seebeck coefficients tend to saturate at high temperatures, presenting narrow-band behavior, as proved by ab initio calculations of the electronic structure. The magnitudes of the Seebeck coefficient and the electrical resistivity decrease with increasing Dy content. At the same time, the thermal conductivity decreases because the lattice thermal conductivity is reduced by Dy substitution. The maximum value of the figure of merit reaches 0.25 at 973 K for the Sr0.9Dy0.1TiO3 sample.

Markedly Enhanced Surface Hydroxyl Groups of TiO2 Nanoparticles with Superior Water-Dispersibility for Photocatalysis

PubMed Central

Wu, Chung-Yi; Tu, Kuan-Ju; Deng, Jin-Pei; Lo, Yu-Shiu; Wu, Chien-Hou

2017-01-01

The benefits of increasing the number of surface hydroxyls on TiO2 nanoparticles (NPs) are known for environmental and energy applications; however, the roles of the hydroxyl groups have not been characterized and distinguished. Herein, TiO2 NPs with abundant surface hydroxyl groups were prepared using commercial titanium dioxide (ST-01) powder pretreated with alkaline hydrogen peroxide. Through this simple treatment, the pure anatase phase was retained with an average crystallite size of 5 nm and the surface hydroxyl group density was enhanced to 12.0 OH/nm2, estimated by thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Especially, this treatment increased the amounts of terminal hydroxyls five- to six-fold, which could raise the isoelectric point and the positive charges on the TiO2 surface in water. The photocatalytic efficiency of the obtained TiO2 NPs was investigated by the photodegradation of sulforhodamine B under visible light irradiation as a function of TiO2 content, pH of solution, and initial dye concentration. The high surface hydroxyl group density of TiO2 NPs can not only enhance water-dispersibility but also promote dye sensitization by generating more hydroxyl radicals. PMID:28772926

XAFS atomistic insight of the oxygen gettering in Ti/HfO 2 based OxRRAM

NASA Astrophysics Data System (ADS)

Viennet, R.; Roussel, H.; Rapenne, L.; Deschanvres, J. L.; Renevier, H.; Jousseaume, V.; Jalaguier, E.; Proietti, M. G.

2018-05-01

Hafnia-based resistive memories technology has come to maturation and acceded to the market of nonvolatile memories. Nevertheless, the physical mechanisms involved in resistive switching are not yet fully understood and the numerous ab initio simulations studies have few many atomic-scale experimental counterparts. In this study we investigate the oxygen migration mechanism from an amorphous HfO2 layer to the Ti cap layer at a local scale before and after a thermal treatment. X-ray absorption spectroscopy at the Ti K edge and Hf LIII edge has been performed on samples as-deposited and annealed in Ar at 400 ∘C to mimic the back-end-of-line thermal budget (BEOL) of CMOS technology. The short-range Ti and Hf environments have been determined, showing that annealing promotes the migration of O from HfO2 to Ti, the amount of which is quantified. This provokes an expansion and an increase of atomic disorder in the Ti lattice. The nature of the oxygen gettering mechanism by the Ti metal is understood by comparing samples with increasing Ti-capping thickness. We show that the Ti getter effect has to be activated by thermal treatment and that the O diffusion takes place in a region of a few nanometers close to the Ti /HfO2 interface. Therefore, the thermal budget history and the Ti cap-layer thickness determine the oxygen vacancy content in the HfO2 layer, which in turn controls the electrical properties, especially the forming operation.

Recovery TiO2 by leaching process of carbothermic reduced Kalimantan ilmenite

NASA Astrophysics Data System (ADS)

Wahyuningsih, S.; Sari, P. P.; Ramelan, A. H.

2018-05-01

Ilmenite naturally occurred in iron titanate (FeTiO3) minerals. The separation of natural ilmenite into TiO2 and Fe2O3 need to be explored to gain the high purity separation product. A new combination method named of carbothermic reduction, acidic-leaching and complexation by EDTA were proposed for separation TiO2 from Ilmenite. Roasting of ilmenite was carried out at 950 °C for 1 h by the addition of activated carbon with mass ratio of ilmenite : activated carbon =4:3. The carbothermic reduction was carried out to yield a high separation of initial content of ilmenite that will be easily to dissolve within hydrochloric acid solution in leaching process. The composition of ilmenite observed by X-Ray Fluoresences (XRF) changed after the carbothermic reduction process and the dominant content is TiO2 (57.56%). X-Ray Diffraction (XRD) of roasted ilmenite composed of decomposed product of ilmenite i.e. hematite (Fe2O3), TiO2 anatase, TiO2 rutile, and inorganic salt. The leaching of the roasted ilmenite has been done by sulphuric acid solution (6 M) to gain the titanyl sulphate solution. Separation of iron impurities of TiO2 gel from titanyl sulphate (TiOSO4) solution was conducted by complexation method using EDTA as a complexation agent. The characteristic of TiO2 obtained using XRD showed that TiO2 is anatase type and the percentage of TiO2 using XRF showed that TiO2 content of 86,03%.

Influence of several plant and animal proteins on rat pancreas.

PubMed

Struthers, B J; MacDonald, J R; Prescher, E E; Hopkins, D T

1983-08-01

Twelve different plant and animal proteins were fed to rats for 4 weeks. Trypsin inhibitor (TI) content of the diet was significantly correlated with (although not directly related in all cases to) pancreas weights and with the pancreatic biochemical parameters that indicate hypertrophy. In vitro, but not in vivo, digestibility was correlated with the TI content of the diet. Quantity of DNA per gram pancreas was not found to be related to TI content. A second experiment compared graded levels of TI from raw or heated soy flour and soy protein isolate (SPI). The SPI diet produced higher relative pancreas weights per TIU than did the flour diets. Two commercial SPI's were fed as is or autoclaved in a third experiment. Autoclaving to very low TI values made no improvement in weight gain or pancreatic parameters measured, indicating that there may be a threshold level of TI below which rat pancreata do not respond, and that other factors in SPI are responsible for the slight pancreatic enlargement seen with SPI compared to casein.

PHASE DIAGRAM FOR THE SYSTEM TITANIUM-TIN (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kornilov, I.I.; Nartova, T.T.

1960-03-01

Differential thermal analysis, microstructural analyses, and determinations of hardness values and electric resistance were used to construct a diagram of state for the binary system Ti-Sn up to the composition of the compound Ti/sub 3/Sn (from 0 to 25 at.% Sn). Analyses of the thermograms showed that all conversions proceeding with the absorption of heat could be detected on the heating curves. Tin lowers the temperature of conversion of titunium with 5.0 at.% tin first to a minimum at 860 tained C which then increases to 890 tained C at higher tin contents. A peritectoid reaction ( alpha / submore » 2/ were ob ore resistant t + ) takes place with a conversion temperature at 890 tained C. A HF-HNO/sub 3/-glycerin etch showed a single-phase homogeneous structure of an alpha -solid solution with alloys containing up to 9 at.% Q. The amount of a second -phase increases with increasing tin content until a single-phase structure of a -solid solution of the compound Ti/sub 3/Sn is noted with alloys containing 23 to 25 at.% Sn. Alloys containing 8 to 22.5 at.% Sn undergo a peritectoid reaction, at a temperature of 890 tained C as shown by thermal analyses and by microstructural analyses of samples quenched frorn above and below the conversion temperature. A study of the microstructure of quenched alloys showed that the solubility of tin in ore resistant t -titanium increases from 8 at.% Sn at 890 tained C to 10.5 at.% Sn at 1100 tained C. X-ray analyses of annealed samples of alloy showed only the lines of an alpha solid solution for 5, 8, 9 at.% Sn, a -solid solution for 23 at.% Sn (close to the composition Ti/sub 3/Sn), and an alpha and mixed phase for a 15 at.% Sn. Vickers hardness numbers were determined with a diamond pyramid at a loading of 10 kg. The hardness increases smoothly with increasing tin content to a maximum at the saturation solubility of the tin in the alpha - or ore resistant t -solid solution. The hardness decreases smoothly with the appearance of the -phase until it attains a minimum at the composition of the compound Ti/sub 3/Sn. The specific electric resistance increases with an increase of tin in the solid solution of alpha -titanium. The rate of increase of the specific electric resistance decreases markedly with the appearance of the -phase. The electric resistance of an alloy with 14.3 at.% Sn was studied as a function of temperature from room temperature to 1100 tained C in special vacuum equipment. A sharp drop in electric resistance a; 890 tained C confirmed the existence of a peritectoid reaction in the system Ti-Sn. (TTT)« less

Complex doping chemistry owing to Mn incorporation in nanocrystalline anatase TiO2 powders.

PubMed

Guo, Meilan; Gao, Yun; Shao, G

2016-01-28

Mn-doped TiO2 powders with a wide range of nominal doping levels were fabricated using a one-step hydrothermal method followed by 400 °C annealing. Anatase powders with a uniform size distribution below 10 nm were obtained. The maximum solubility of Mn in the TiO2 lattice was around 30%, beyond which the Mn3O4 compound appeared as a secondary phase. The optical absorption edges for Mn-doped anatase TiO2 were red-shifted effectively through increasing Mn content. Alloying chemistry and associated elemental valences were elaborated through combining X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and theoretical simulation in the framework of density functional theory (DFT). The results showed that the Mn species exhibited mixed valence states of 3+ and 4+ in anatase TiO2, with the latter being the key to remarkable photocatalytic performance.

Kontay intrusion (Polar Siberia)- an example of strong magmatic differentiation in the single magmatic body

NASA Astrophysics Data System (ADS)

Zaitsev, Victor

2016-04-01

Kontay intrusion is located in the north-west part of Maimecha-Kotuy province, (part of Siberian Large Igneous Province) in the northern part of the Siberian Platform. Intrusion is fully overlaid and practically not studied before. Geophysical data evident that intrusion has form of laccolite with diameter ˜7.5 km and thickness ˜ 2.5 km [1]. Initially lower part of intrusion was described as "gabbro-anortozite and anortositic gabbro" and higher part - as "leucocratic granophyric anortosites" [2]. Complex mineralo-petrological-geochemical study allow to divide intrusion section on three zones: Lower zone (below 1100 m) - layered sequence of leucocratic and melanocratic of biotite- and ortopyroxene-bearing gabbro, with minor alkaline feldspar, Middle zone (1100-700m) - biotite- and K-feldspar bearing gabbro and monzonotes, interstitial space often contain micrographical structures. Biotite corroded clinopyroxene and form interstitial crystals and Upper zone (700-214 m) - petrographically monotone porthyric quartz-monzonites and granosyenites with rare phenocrysts of plagioclase, magnetite, clinopyroxene and biotite. The main secondary minerals are albite, amphibole (edenite-feroedenite), secondary biotite, chlorite, and F,Al-bearing titanite. Rocks of the all parts fall in the same trends on the binary petrochemical diagrams, they belong to the High-K calc-alkaline seria. They are clearly more alkaline then intrusions of Norilsk district and less alkaline then alkaline-ultramafic intrusions of Maymecha-Kotuy province. Volcanic rocks of Norilsk and Maymecha-Kotuy area was subdivided for four geochemical types, mainly by the Ti-content, Th/U, Gd/Yb and Sm/Yb ratio: Low-Ti-1 (predominated), Low-Ti-2 (well -developed in Norilsk region), Moderate-Ti (developed only in the lower part of volcanic formation in Norilsk region), High-Ti (rare in Norilsk region, but widely spread in Mailecha-Kotuy area) [3]. Kontay intrusion rocks belong to Moderate-Ti group. The closest analog is Ivakinsky-1 subsute. Cumulus minerals composition changed systematically upward. Two populations of clinopyroxene occur, both are diopside-hedenbergite. The pyroxenes of first population contain 1-1.2% TiO22-2.5% Al2O3 0.2-0.3 % MnO, 0.3-0.35% Na2O, Mg/(Mg+Fe)=0.44-0.50 present only in the lower part of intrusion. These pyroxenes was formed from the melt of High-Ti geochemical type; the second population of pyroxene present overall, Mg/(Mg+Fe) decrease from 0.7 to 0.63, concentration of Al2O3 increase from 0.7 to 1.3, TiO2 increase from 0.4 to 0.6, MnO from 0.4 to 0.7 and Na2O decrease from 0.32 to 0.28 wt%. Biotite Mg/(Mg+Fe) increase from 0.60-0.62 up to 0.76-0.78, TiO2 content decrease from 5 -6.2% to 1.9-2.4%, and MnO content increase from 0.1 to 0.3-0.4%. Plagioclase in the lowest part of intrusion contains An60-An45 cores and An32-An26rims, but in the middle and upper zone plagioclase composition of plagioclase changed systematically with an increase in Ca. Based on the petrochemical and mineralogical data, Kontay intrusion is an example of strongly in-situ differentiated layered intrusion, formed in subvolcanic conditions form the subalkaline moderate-Ti melt with admixture of crystals, genetically linked with high-Ti melts. This study was financially supported by the Russian Science Foundation (grant 115-17-30019) [1] Kushnir (2005) Ph.d. thesises, 25.00.10 Ekatirenburg, 154. [2] Lopatin and Kalashnik (2004) Mineral resourses and perspectives of Taimyr district. 154-156 [3] Fedorenko et al. (2000) International Geology Review. 42. 769-804.

Science Scores in Title I Elementary Schools in North Georgia: A Project Study

NASA Astrophysics Data System (ADS)

Frias, Ramon

The No Child Left Behind Act (NCLB)'s emphasis of reading, language arts, and mathematics (RLA&M) and its de-emphasis of science has been a source of great concern among educators. Through an objectivist and constructionist framework, this study explored the unforeseen effects of the NCLB on public science education among Title I (TI) and non-Title I (NTI) students. The research questions focused on the effects of NCLB on Criterion Referenced Competency Test (CRCT) scores in the high-stakes subjects of reading, language arts, mathematics and the low stakes subject of science among TI and NTI 3rd, 4th, and 5th grade students in a north Georgia County during the 2010/2011 school year. This study also compared instructional time TI and NTI teachers dedicated to science. A causal-comparative quantitative methodology was used to analyze Georgia's public domain CRCT scores. Three independent-samples t tests showed that TI schools exhibited significantly lower Science CRCT scores than did NTI students at all grade levels (p < 0.0001). The data also showed CRCT scores in high-stakes subjects between TI and NTI students converging but science CRCT scores between TI and NTI students diverging. The self-report survey indicated no significant differences between TI and NTI teachers' instructional science time (t (107) = 1.49, p = 0.137). A teacher development project was designed to focus on improving teacher science content knowledge and pedagogical content knowledge through a formal introduction to the nature of science. With increasing global science competition, science is more relevant than ever, and communities need students with strong science foundations. Further study is recommended to analyze the factors associated with this science gap between TI and NTI students.

Remote sensing of potential lunar resources. 2: High spatial resolution mapping of spectral reflectance ratios and implications for nearside mare TiO2 content`

NASA Technical Reports Server (NTRS)

Melendrez, David E.; Johnson, Jeffrey R.; Larson, Stephen M.; Singer, Robert B.

1994-01-01

High spatial resolution maps illustrating variations in spectral reflectance 400/560 nm ratio values have been generated for the following mare regions: (1) the border between southern Mare Serenitatis and northern Mare Tranquillitatis (including the MS-2 standard area and Apollo 17 landing site), (2) central Mare Tranquillitatis, (3) Oceanus Procellarum near Seleucus, and (4) southern Oceanus Procellarum and Flamsteed. We have also obtained 320-1000 nm reflectance spectra of several sites relative to MS-2 to facilitate scaling of the images and provide additional information on surface composition. Inferred TiO2 abundances for these mare regions have been determined using an empirical calibration which relates the weight percent TiO2 in mature mare regolith to the observed 400/560 nm ratio. Mare areas with high TiO2 abundances are probably rich in ilmenite (FeTiO3) a potential lunar resource. The highest potential TiO2 concentrations we have identified in the nearside maria occur in central Mare Tranquillitatis. Inferred TiO2 contents for these areas are greater than 9 wt% and are spatially consistent with the highest-TiO2 regions mapped previously at lower spatial resolution. We note that the morphology of surface units with high 400/560 nm ratio values increases in complexity at higher spatial resolutions. Comparisons have been made with previously published geologic maps, Lunar Orbiter IV, and ground-based images, and some possible morphologic correlatins have been found between our mapped 400/560 nm ratio values and volcanic landforms such as lava flows, mare domes, and collapse pits.

Human alveolar bone cell proliferation, expression of osteoblastic phenotype, and matrix mineralization on porous titanium produced by powder metallurgy.

PubMed

Rosa, Adalberto Luiz; Crippa, Grasiele Edilaine; de Oliveira, Paulo Tambasco; Taba, Mario; Lefebvre, Louis-Philippe; Beloti, Marcio Mateus

2009-05-01

This study aimed at investigating the influence of the porous titanium (Ti) structure on the osteogenic cell behaviour. Porous Ti discs were fabricated by the powder metallurgy process with the pore size typically between 50 and 400 microm and a porosity of 60%. Osteogenic cells obtained from human alveolar bone were cultured until subconfluence and subcultured on dense Ti (control) and porous Ti for periods of up to 17 days. Cultures grown on porous Ti exhibited increased cell proliferation and total protein content, and lower levels of alkaline phosphatase (ALP) activity than on dense Ti. In general, gene expression of osteoblastic markers-runt-related transcription factor 2, collagen type I, alkaline phosphatase, bone morphogenetic protein-7, and osteocalcin was lower at day 7 and higher at day 17 in cultures grown on porous Ti compared with dense Ti, a finding consistent with the enhanced growth rate for such cultures. The amount of mineralized matrix was greater on porous Ti compared with the dense one. These results indicate that the porous Ti is an appropriate substrate for osteogenic cell adhesion, proliferation, and production of a mineralized matrix. Because of the three-dimensional environment it provides, porous Ti should be considered an advantageous substrate for promoting desirable implant surface-bone interactions.

Development of β Type Ti23Mo-45S5 Bioglass Nanocomposites for Dental Applications

PubMed Central

Jurczyk, Karolina; Miklaszewski, Andrzej; Jurczyk, Mieczyslawa U.; Jurczyk, Mieczyslaw

2015-01-01

Titanium β-type alloys attract attention as biomaterials for dental applications. The aim of this work was the synthesis of nanostructured β type Ti23Mo-x wt % 45S5 Bioglass (x = 0, 3 and 10) composites by mechanical alloying and powder metallurgy methods and their characterization. The crystallization of the amorphous material upon annealing led to the formation of a nanostructured β type Ti23Mo alloy with a grain size of approximately 40 nm. With the increase of the 45S5 Bioglass contents in Ti23Mo, nanocomposite increase of the α-phase is noticeable. The electrochemical treatment in phosphoric acid electrolyte resulted in a porous surface, followed by bioactive ceramic Ca-P deposition. Corrosion resistance potentiodynamic testing in Ringer solution at 37 °C showed a positive effect of porosity and Ca-P deposition on nanostructured Ti23Mo 3 wt % 45S5 Bioglass nanocomposite. The contact angles of glycerol on the nanostructured Ti23Mo alloy were determined and show visible decrease for bulk Ti23Mo 3 wt % 45S5 Bioglass and etched Ti23Mo 3 wt % 45S5 Bioglass nanocomposites. In vitro tests culture of normal human osteoblast cells showed very good cell proliferation, colonization, and multilayering. The present study demonstrated that porous Ti23Mo 3 wt % 45S5 Bioglass nanocomposite is a promising biomaterial for bone tissue engineering. PMID:28793695

Lanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV-visible light

NASA Astrophysics Data System (ADS)

Dal'Toé, Adrieli T. O.; Colpani, Gustavo Lopes; Padoin, Natan; Fiori, Márcio Antônio; Soares, Cíntia

2018-05-01

Lanthanum doped titanium dioxide decorated with silver plasmonic nanoparticles (Ag-La/TiO2 NPs) materials were prepared using a simple ultrasound-assisted wet impregnation method followed by silver photodeposition. The obtained photocatalysts with different Ag contents were characterized by XRD, FE-SEM, EDX, TEM, BET, XPS, DRS and PL techniques. Moreover, the size distribution of the nanoparticles aggregates was assessed. The characterization analysis revealed that La doping slightly changed the crystalline phase of TiO2, increased the amount of surface hydroxyl groups and interacted with TiO2 nanoparticles via Ti-O-La bond, while Ag photodeposition enhanced the absorption of visible light due to the effects of localized surface plamon resonance and significantly decreased electronic recombination rate by the Schottky junction. Furthermore, the combination of Ag-La induced the formation of oxygen vacancies, which increased the amount of adsorbed surface hydroxyl groups in Ag-La/TiO2. In addition, Ag-La possibly decreased the semiconductor surface energy, which acted positively in the reduction of NPs aggregation. These features along with better textural properties (greater surface areas) played a fundamental role in the enhancement of the photocatalytic activity of Ag-La/TiO2 composites for the decolorization of methylene blue under UV-visible irradiation compared to the mono-metallic (La/TiO2 and Ag/TiO2) modified photocatalysts. Finally, a mechanism for the transfer of charge carriers in Ag-La/TiO2 photocatalyst under UV-visible irradiation was proposed.

High-pressure phase transitions of Fe 3-xTi xO 4 solid solution up to 60 GPa correlated with electronic spin transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamanaka, Takamitsu; Kyono, Atsushi; Nakamoto, Yuki

2013-06-12

The structural phase transition of the titanomagnetite (Fe 3–xTi xO 4) solid solution under pressures up to 60 GPa has been clarified by single-crystal and powder diffraction studies using synchrotron radiation and a diamond-anvil cell. Present Rietveld structure refinements of the solid solution prove that the prefered cation distribution is based on the crystal field preference rather than the magnetic spin ordering in the solid solution. The Ti-rich phases in 0.734 ≤ x ≤1.0 undergo a phase transformation from the cubic spinel of Fd3m to the tetragonal spinel structure of I4 1/amd with c/a < 1.0. The transition is drivenmore » by a Jahn-Teller effect of IVFe 2+ (3d 6) on the tetrahedral site. The c/a < 1 ratio is induced by lifting of the degeneracy of the e orbitals by raising the d x2-y2 orbital below the energy of the d z2 orbital. The distortion characterized by c/a < 1 is more pronounced with increasing Ti content in the Fe 3–xTi xO 4 solid solutions and with increasing pressure. An X-ray emission experiment of Fe 2TiO 4 at high pressures confirms the spin transition of FeKβ from high spin to intermediate spin (IS) state. The high spin (HS)-to-low spin (LS) transition starts at 14 GPa and the IS state gradually increases with compression. The VIFe 2+ in the octahedral site is more prone for the HS-to-LS transition, compared with Fe 2+ in the fourfold- or eightfold-coordinated site. The transition to the orthorhombic post-spinel structure with space group Cmcm has been confirmed in the whole compositional range of Fe 3–xTi xO 4. The transition pressure decreases from 25 GPa (x = 0.0) to 15 GPa (x = 1.0) with increasing Ti content. There are two cation sites in the orthorhombic phase: M1 and M2 sites of eightfold and sixfold coordination, respectively. Fe 2+ and Ti 4+ are disordered on the M2 site. This structural change is accelerated at higher pressures due to the spin transition of Fe 2+ in the octahedral site. This is because the ionic radius of VIFe 2+ becomes 20% shortened by the spin transition. At 53 GPa, the structure transforms to another high-pressure polymorph with Pmma symmetry with the ordered structure of Ti and Fe atoms in the octahedral site. This structure change results from the order-disorder transition.« less

Influence of microstructure and AlPO4 secondary-phase on the ionic conductivity of Li1.3Al0.3Ti1.7(PO4)3 solid-state electrolyte

NASA Astrophysics Data System (ADS)

Yu, Shicheng; Mertens, Andreas; Gao, Xin; Gunduz, Deniz Cihan; Schierholz, Roland; Benning, Svenja; Hausen, Florian; Mertens, Josef; Kungl, Hans; Tempel, Hermann; Eichel, Rüdiger-A.

2016-09-01

A ceramic solid-state electrolyte of lithium aluminum titanium phosphate with the composition of Li1.3Al0.3Ti1.7(PO4)3 (LATP) was synthesized by a sol-gel method using a pre-dissolved Ti-source. The annealed LATP powders were subsequently processed in a binder-free dry forming method and sintered under air for the pellet preparation. Phase purity, density, microstructure as well as ionic conductivity of the specimen were characterized. The highest density (2.77gṡcm-3) with an ionic conductivity of 1.88×10-4 Sṡcm-1 (at 30∘C) was reached at a sintering temperature of 1100∘C. Conductivity of LATP ceramic electrolyte is believed to be significantly affected by both, the AlPO4 secondary phase content and the ceramic electrolyte microstructure. It has been found that with increasing sintering temperature, the secondary-phase content of AlPO4 increased. For sintering temperatures above 1000∘C, the secondary phase has only a minor impact, and the ionic conductivity is predominantly determined by the microstructure of the pellet, i.e. the correlation between density, porosity and particle size. In that respect, it has been demonstrated, that the conductivity increases with increasing particle size in this temperature range and density.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Zeen; Hu, Rui; Zhang, Tiebang, E-mail: tiebang

The microstructure and solidification behavior of high Nb containing TiAl alloys with the composition of Ti-46Al-8Nb-xC (x = 0.1, 0.7, 1.4, 2.5 at.%) prepared by arc-melting method have been investigated in this work. The results give evidence that the addition of carbon changes the solidification behavior from solidification via the β phase to the peritectic solidification. And carbon in solid solution enriches in the α{sub 2} phase and increases the microhardness. As the carbon content increases to 1.4 at.%, plate-shape morphology carbides Ti{sub 2}AlC (H phase) precipitate from the TiAl matrix which leads to the refinement microstructure. By aging atmore » 1173 K for 24 h after quenching treatment, fine needle-like and granular shape Ti{sub 3}AlC (P phase) carbides are observed in the matrix of Ti-46Al-8Nb-2.5C alloy, which distribute along the lamellar structure or around the plate-shape Ti{sub 2}AlC. Transmission electron microscope observation shows that the Ti{sub 3}AlC carbides precipitate at dislocations. The phase transformation in-situ observations indicate that the Ti{sub 2}AlC carbides partly precipitate during the solid state phase transformation process. - Highlights: •Carbon changes the solidification behavior from β phase to peritectic solidification. •Dislocations in solution treated γ phase act as nucleation sites of Ti{sub 3}AlC precipitations. •Ti{sub 3}AlC precipitates as fine needle-like or granular shape in the solution treated matrix. •Ti{sub 2}AlC carbides precipitate during the solid state phase transformation process.« less

Maternal exposure to nanosized titanium dioxide suppresses embryonic development in mice.

PubMed

Hong, Fashui; Zhou, Yingjun; Zhao, Xiaoyang; Sheng, Lei; Wang, Ling

2017-01-01

Although nanoscale titanium dioxide (nano-TiO 2 ) has been extensively used in industrial food applications and daily products for pregnant women, infants, and children, its potential toxicity on fetal development has been rarely studied. The main objective of this investigation was to establish the effects of maternal exposure of nano-TiO 2 on developing embryos. Female imprinting control region mice were orally administered nano-TiO 2 from gestational day 0 to 17. Our findings showed that Ti concentrations in maternal serum, placenta, and fetus were increased in nano-TiO 2 -exposed mice when compared to controls, which resulted in reductions in the contents of calcium and zinc in maternal serum, placenta, and fetus, maternal weight gain, placental weight, fetal weight, number of live fetuses, and fetal crown-rump length as well as cauda length, and caused an increase in the number of both dead fetuses and resorptions. Furthermore, maternal nano-TiO 2 exposure inhibited development of the fetal skeleton, suggesting a significant absence of cartilage, reduced or absent ossification, and an increase in the number of fetuses with dysplasia, including exencephaly, spina bifida, coiled tail, scoliosis, rib absence, and sternum absence. These findings indicated that nano-TiO 2 can cross the blood-fetal barrier and placental barrier, thereby delaying the development of fetal mice and inducing skeletal malformation. These factors may be associated with reductions in both calcium and zinc in maternal serum and the fetus, and both the placenta and embryos may be major targets of developmental toxicity following maternal exposure to nano-TiO 2 during the prenatal period. Therefore, the application of nano-TiO 2 should be carried out with caution.

Chromium incorporation into TiO{sub 2} at high pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Escudero, Alberto, E-mail: aescudero@icmse.csic.es; Langenhorst, Falko; Institut fuer Geowissenschaften, Friedrich-Schiller-Universitaet Jena, Carl-Zeiss-Promenade 10, D-07745 Jena

2012-06-15

Chromium incorporation into TiO{sub 2} up to 3 GPa at 1300 Degree-Sign C and 900 Degree-Sign C has been studied by XRD as well as TEM. A CaCl{sub 2} type TiO{sub 2} polymorph has been observed in the quenched samples from high pressure. Two different mechanisms of solubility occur in the recovered samples. Chromium replaces titanium on normal octahedral sites but it also occupies interstitial octahedral sites, especially in the samples recovered from higher pressures. Interstitial chromium is responsible for an orthorhombic distortion of the TiO{sub 2} rutile structure in the quenched samples and gives rise to a (1 1more » 0) twinned CaCl{sub 2}-structured polymorph. This phase is very likely the result of temperature quench at high pressure. The formation of this phase is directly related to the chromium content of the TiO{sub 2} grains. Chromium solubility in TiO{sub 2} increases with increasing the synthesis pressure. TiO{sub 2} is able to accommodate up to 15.3 wt% Cr{sub 2}O{sub 3} at 3 GPa and 1300 Degree-Sign C, compared to 5.7 wt% at atmospheric pressure at the same temperature. - Graphical abstract: Microstructure consisting of twins domains of recovered Cr-doped CaCl{sub 2} type TiO{sub 2} grains synthesised at high pressure. Highlights: Black-Right-Pointing-Pointer Chromium solubility in TiO{sub 2} increases at high pressure. Black-Right-Pointing-Pointer Chromium occupies substitutional and interstitial positions in the rutile structure. Black-Right-Pointing-Pointer Interstitial chromium causes a decrease of the rutile symmetry. Black-Right-Pointing-Pointer An orthorhombic CaCl{sub 2} type structure is observed in the quenched samples.« less

Maternal exposure to nanosized titanium dioxide suppresses embryonic development in mice

PubMed Central

Hong, Fashui; Zhou, Yingjun; Zhao, Xiaoyang; Sheng, Lei; Wang, Ling

2017-01-01

Although nanoscale titanium dioxide (nano-TiO2) has been extensively used in industrial food applications and daily products for pregnant women, infants, and children, its potential toxicity on fetal development has been rarely studied. The main objective of this investigation was to establish the effects of maternal exposure of nano-TiO2 on developing embryos. Female imprinting control region mice were orally administered nano-TiO2 from gestational day 0 to 17. Our findings showed that Ti concentrations in maternal serum, placenta, and fetus were increased in nano-TiO2-exposed mice when compared to controls, which resulted in reductions in the contents of calcium and zinc in maternal serum, placenta, and fetus, maternal weight gain, placental weight, fetal weight, number of live fetuses, and fetal crown–rump length as well as cauda length, and caused an increase in the number of both dead fetuses and resorptions. Furthermore, maternal nano-TiO2 exposure inhibited development of the fetal skeleton, suggesting a significant absence of cartilage, reduced or absent ossification, and an increase in the number of fetuses with dysplasia, including exencephaly, spina bifida, coiled tail, scoliosis, rib absence, and sternum absence. These findings indicated that nano-TiO2 can cross the blood–fetal barrier and placental barrier, thereby delaying the development of fetal mice and inducing skeletal malformation. These factors may be associated with reductions in both calcium and zinc in maternal serum and the fetus, and both the placenta and embryos may be major targets of developmental toxicity following maternal exposure to nano-TiO2 during the prenatal period. Therefore, the application of nano-TiO2 should be carried out with caution. PMID:28883729

Welding of 316L Austenitic Stainless Steel with Activated Tungsten Inert Gas Process

NASA Astrophysics Data System (ADS)

Ahmadi, E.; Ebrahimi, A. R.

2015-02-01

The use of activating flux in TIG welding process is one of the most notable techniques which are developed recently. This technique, known as A-TIG welding, increases the penetration depth and improves the productivity of the TIG welding. In the present study, four oxide fluxes (SiO2, TiO2, Cr2O3, and CaO) were used to investigate the effect of activating flux on the depth/width ratio and mechanical property of 316L austenitic stainless steel. The effect of coating density of activating flux on the weld pool shape and oxygen content in the weld after the welding process was studied systematically. Experimental results indicated that the maximum depth/width ratio of stainless steel activated TIG weld was obtained when the coating density was 2.6, 1.3, 2, and 7.8 mg/cm2 for SiO2, TiO2, Cr2O3, and CaO, respectively. The certain range of oxygen content dissolved in the weld, led to a significant increase in the penetration capability of TIG welds. TIG welding with active fluxes can increase the delta-ferrite content and improves the mechanical strength of the welded joint.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Richa; Tandon, R. P., E-mail: ram-tandon@hotmail.com

In the present work, (1-x)Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3}-(x)CoFe{sub 1.8}Mn{sub 0.2}O{sub 4} composites are prepared by standard solid state reaction method. The X-ray diffraction measurement of the composites shows that both the phases coexist in the composite, individually. The morphology of the composites were examined by field emission scanning electron microscopy and reveals homogeneous microstructure with two types of grains, smaller grains of the Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} (BST) and bigger grains of the CoFe{sub 1.8}Mn{sub 0.2}O{sub 4} (CFM). The dielectric studies show that all the composites exhibit dispersion in the lower frequency region attributable to the interfacial polarization. In addition,more » at lower frequencies, the dielectric constant (ε´) is found to increase with increase in CFM content in the composites. The ferromagnetic properties of the composites improve with the increase in the CFM content.« less

Characterization and corrosion study of NiTi laser surface alloyed with Nb or Co

NASA Astrophysics Data System (ADS)

Ng, K. W.; Man, H. C.; Yue, T. M.

2011-02-01

The interest in NiTi alloys for medical applications has been steadily growing in recent years because of its biocompatibility, superelasticity and shape memory characteristics. However, the high Ni content in NiTi alloys is still a concern for its long-term applications in the human body. The release of Ni ion into the human body might cause serious problems, as Ni is capable of eliciting toxic and allergic responses. In view of this, surface modification to reduce the surface content of Ni and to improve the corrosion resistance, both of which would reduce Ni release, is an important step in the development of NiTi implants. In the present study, NiTi was surface alloyed with Nb or Co by laser processing. The fine dendritic structure characteristic of laser processing has been described in terms of rapid solidification. The amount of surface elemental Ni was reduced to 10% and 35% for the Nb-alloyed and Co-alloyed layer, respectively. The corrosion resistance in Hanks' solution (a simulated body fluid) was increased as evidenced by a reduced passive current density and a higher pitting potential for both the Nb- and Co-alloyed specimens. The composition and hardness profiles along the depth of the modified layer were correlated with the distribution of the dendrites. The microhardness of the alloyed layers was around 700-800 Hv, which was about four times that of the untreated NiTi specimens.

Bandgap tailoring of in-situ nitrogen-doped TiO₂ sputtered films intended for electrophotocatalytic applications under solar light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delegan, N.; El Khakani, M. A., E-mail: elkhakani@emt.inrs.ca; Daghrir, R.

2014-10-21

We report on a reactive RF-sputtering process permitting the in-situ nitrogen doping of TiO₂ films in order to shift their photoactivity from UV to visible range. By carefully controlling the relative nitrogen-to-argon mass flow rate ratio (within the 0%–25% range) in the sputter deposition chamber, TiO₂:N films were grown with nitrogen contents ranging from 0 to 6.2 at. %, as determined by high-resolution X-ray spectroscopy measurements. A systematic investigation of the crystalline structure of the TiO₂:N films, as a function of their N content, revealed that low N contents (0.2–0.3 at. %) induce crystallization in the rutile phase while highermore » N contents (≥1.4 at. %) were accompanied with the recovery of the anatase structure with an average crystallite size of ~35 nm. By using both UV-Vis absorption and spectroscopic ellipsometry measurements, we were able to quantitatively determine the bandgap (E{sub g}) variation of the TiO₂:N films as a function of their N content. Thus, we have demonstrated that the E{sub g} of the TiO₂:N films effectively narrows from 3.2 eV down to a value as low as ~2.3 eV for the optimal N doping concentration of 3.4 at. % (higher N incorporation does not translate into further red shifting of the TiO₂:N films' E{sub g}). The photoactivity of the TiO₂:N films under visible light was confirmed through electro-photocatalytic decomposition of chlortetracycline (CTC, an emerging water pollutant) under standard 1.5AM solar radiation. Thus, CTC degradation efficiencies of up to 98% were achieved with 2 hours process cycles under simulated solar light. Moreover, the electro-photocatalytic performance of the TiO₂:N films is shown to be directly correlated to their optoelectronic properties (namely their bandgap narrowing).« less

Sodium fluoride-assisted modulation of anodized TiO₂ nanotube for dye-sensitized solar cells application.

PubMed

Yun, Jung-Ho; Ng, Yun Hau; Ye, Changhui; Mozer, Attila J; Wallace, Gordon G; Amal, Rose

2011-05-01

This work reports the use of sodium fluoride (in ethylene glycol electrolyte) as the replacement of hydrofluoric acid and ammonium fluoride to fabricate long and perpendicularly well-aligned TiO₂ nanotube (TNT) (up to 21 μm) using anodization. Anodizing duration, applied voltage and electrolyte composition influenced the geometry and surface morphologies of TNT. The growth mechanism of TNT is interpreted by analyzing the current transient profile and the total charge density generated during anodization. The system with low water content (2 wt %) yielded a membrane-like mesoporous TiO₂ film, whereas high anodizing voltage (70 V) resulted in the unstable film of TNT arrays. An optimized condition using 5 wt % water content and 60 V of anodizing voltage gave a stable array of nanotube with controllable length and pore diameter. Upon photoexcitation, TNTs synthesized under this condition exhibited a slower charge recombination rate as nanotube length increased. When made into cis-diisothiocyanato-bis(2,2̀-bipyridyl-4,4̀-dicarboxylato) ruthenium(II) bis (tetrabutyl-ammonium)(N719) dye-sensitized solar cells, good device efficiency at 3.33 % based on the optimized TNT arrays was achieved with longer electron time compared with most mesoporous TiO₂ films.

Study of the structure, dielectric and ferroelectric behavior of BaBi4+δTi4O15 ceramics

NASA Astrophysics Data System (ADS)

Khokhar, Anita; Goyal, Parveen K.; Thakur, O. P.; Sreenivas, K.

2016-05-01

The structure and ferroelectric properties of excess bismuth doped barium bismuth titanate BaBi4+δTi4O15 (δ = 2 - 10 wt.%)) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material with a change in the orthorhombic distortion with varying excess of bismuth content. There is no change in the phase transition temperature (Tm) while the relaxor behaviour has been modified significantly with excess of bismuth doping. Saturated hysteresis loops with high remnant polarization (Pr ~ 12.5 µC/cm2), low coercive fields (Ec ~ 26 kV/cm) are measured and a high piezoelectric coefficient (d33 ~ 29 pC/N) is achieved in poled BaBi4Ti4O15 ceramics prepared with up to 8 wt.% of excess bismuth oxide. The improvement in the ferroelectric properties with increase in the excess bismuth content in BaBi4Ti4O15 ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of excess bismuth.

Optical properties of zinc titanate perovskite prepared by reactive RF sputtering

NASA Astrophysics Data System (ADS)

Müllerová, Jarmila; Šutta, Pavol; Medlín, Rostislav; Netrvalová, Marie; Novák, Petr

2017-12-01

In this paper we report results from optical transmittance spectroscopy complemented with data on structure from XRD measurements to determine optical properties of a series of ZnTiO3 perovskite thin films deposited on glass by reactive magnetron co-sputtering. The members of the series differ by the titanium content that was revealed as an origin of the changes not only in structure but also in dispersive optical properties. Low porosity has been discovered and calculated using the Bruggeman effective medium approximation. An apparent blue-shift of the optical band gap energies with increasing titanium content was observed. The observed band gap engineering is a good prospective for eg optoelectronic and photocatalytic applications of ZnTiO3.

Effect of Mo on Microstructures and Wear Properties of In Situ Synthesized Ti(C,N)/Ni-Based Composite Coatings by Laser Cladding.

PubMed

Wu, Fan; Chen, Tao; Wang, Haojun; Liu, Defu

2017-09-06

Using Ni60 alloy, C, TiN and Mo mixed powders as the precursor materials, in situ synthesized Ti(C,N) particles reinforcing Ni-based composite coatings are produced on Ti6Al4V alloys by laser cladding. Phase constituents, microstructures and wear properties of the composite coatings with 0 wt % Mo, 4 wt % Mo and 8 wt % Mo additions are studied comparatively. Results indicate that Ti(C,N) is formed by the in situ metallurgical reaction, the (Ti,Mo)(C,N) rim phase surrounding the Ti(C,N) ceramic particle is synthesized with the addition of Mo, and the increase of Mo content is beneficial to improve the wear properties of the cladding coatings. Because of the effect of Mo, the grains are remarkably refined and a unique core-rim structure that is uniformly dispersed in the matrix appears; meanwhile, the composite coatings with Mo addition exhibit high hardness and excellent wear resistance due to the comprehensive action of dispersion strengthening, fine grain strengthening and solid solution strengthening.

Effect of Mo on Microstructures and Wear Properties of In Situ Synthesized Ti(C,N)/Ni-Based Composite Coatings by Laser Cladding

PubMed Central

Chen, Tao; Wang, Haojun

2017-01-01

Using Ni60 alloy, C, TiN and Mo mixed powders as the precursor materials, in situ synthesized Ti(C,N) particles reinforcing Ni-based composite coatings are produced on Ti6Al4V alloys by laser cladding. Phase constituents, microstructures and wear properties of the composite coatings with 0 wt % Mo, 4 wt % Mo and 8 wt % Mo additions are studied comparatively. Results indicate that Ti(C,N) is formed by the in situ metallurgical reaction, the (Ti,Mo)(C,N) rim phase surrounding the Ti(C,N) ceramic particle is synthesized with the addition of Mo, and the increase of Mo content is beneficial to improve the wear properties of the cladding coatings. Because of the effect of Mo, the grains are remarkably refined and a unique core-rim structure that is uniformly dispersed in the matrix appears; meanwhile, the composite coatings with Mo addition exhibit high hardness and excellent wear resistance due to the comprehensive action of dispersion strengthening, fine grain strengthening and solid solution strengthening. PMID:28878190

Abnormal cubic-tetragonal phase transition of barium strontium titanate nanoparticles studied by in situ Raman spectroscopy and transmission electron microscopy heating experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yin; Chen, Chen; Gao, Ran

2015-11-02

Phase stability of the ferroelectric materials at high temperature is extremely important to their device performance. Ba{sub x}Sr{sub 1−x}TiO{sub 3} (BST) nanoparticles with different Sr contents (x = 1, 0.91, 0.65, 0.4, and 0) are prepared by a facile hydrothermal method. Using Raman spectroscopy and transmission electron microscopy (TEM) analyses under in situ heating conditions (up to 300 °C), the phase transitions of BST nanoparticles between 25 °C and 280 °C are comprehensively investigated. The original Curie temperature of BST nanoparticles decreases abruptly with the increase in Sr content, which is more obvious than in the bulk or film material. Besides, an abnormal phase transitionmore » from cubic to tetragonal structure is observed from BST nanoparticles and the transition temperature rises along with the increase in Sr content. Direct TEM evidences including a slight lattice distortion have been provided. Differently, BaTiO{sub 3} nanoparticles remained in the tetragonal phase during the above temperature ranges.« less

Materials Performance in USC Steam Portland

DOE Office of Scientific and Technical Information (OSTI.GOV)

G.R. Holcomb; J. Tylczak; R. Hu

2011-04-26

Goals of the U.S. Department of Energy's Advanced Power Systems Initiatives include power generation from coal at 60% efficiency, which requires steam conditions of up to 760 C and 340 atm, co-called advanced ultrasupercritical (A-USC) steam conditions. A limitation to achieving the goal is a lack of cost-effective metallic materials that can perform at these temperatures and pressures. Some of the more important performance limitations are high-temperature creep strength, fire-side corrosion resistance, and steam-side oxidation resistance. Nickel-base superalloys are expected to be the materials best suited for steam boiler and turbine applications above about 675 C. Specific alloys of interestmore » include Haynes 230 and 282, Inconel 617, 625 and 740, and Nimonic 263. Further validation of a previously developed chromia evaporation model is shown by examining the reactive evaporation effects resulting from exposure of Haynes 230 and Haynes 282 to moist air environments as a function of flow rate and water content. These two alloys differ in Ti and Mn contents, which may form outer layers of TiO{sub 2} or Cr-Mn spinels. This would in theory decrease the evaporation of Cr{sub 2}O{sub 3} from the scale by decreasing the activity of chromia at the scale surface, and be somewhat self-correcting as chromia evaporation concentrates the Ti and Mn phases. The apparent approximate chromia activity was found for each condition and alloy that showed chromia evaporation kinetics. As expected, it was found that increasing the gas flow rate led to increased chromia evaporation and decreased chromia activity. However, increasing the water content in moist air increased the evaporation, but results were mixed with its effect on chromia activity.« less

Matrix effects for elemental fractionation within ICPMS: applications for U-Th-Pb geochronology

NASA Astrophysics Data System (ADS)

Chen, W.

2016-12-01

Recent development in instruments provides significant technical supports for daily, quick, money saving geochemical analyses. Laser ablation ICPMS stands out due to these reasons, especially for the U-Th-Pb isotopic dating. Matrix-matched external standardization is by far the most common approach used in U-Th-Pb dating via LA-ICPMS. However, matrix-effects between standard and sample for in-situ dating have shown to be both significant and insignificant. It remains mysterious whether a well matrix-matched standard is needed for U-Th-Pb dating by LA-ICPMS. This study provides an experimental framework for the understanding of matrix effects induced elemental fractionation for U-Th-Pb associated with ICPMS. A preliminary study on the influence of varied U, Th and Pb amounts on their fractionations has been carried out. Experimental data show that different U, Th and Pb contents result in varied 238U/206Pb and 232Th/208Pb ratios. The fractionations of U/Pb and Th/Pb increase with the increasing contents (1 ppb to 100 ppb) with a strong positive anomaly at 10 ppb. Matrixes representing minerals frequently used in dating have been investigated for the influences on U/Pb and Th/Pb fractionations, which suggest a complicated effect. Little fractionations observed between mineral pairs (e.g., monazite and apatite; zircon and perovskite; rutile and perovskite; xenotime and baddeleyite), whereas large fractionations identified for other minerals (e.g., zircon and baddeleyite; monazite and sphene; rutile and baddeleyite). Single element matrix (i.e., Si, P, Ca, Zr, Ti) has been studied to identify their effects on the fractionations. U/Pb ratio increases with the increasing Si and P contents, whereas it decreases for Zr, Ca and Ti. Th/Pb ratio increases with increasing Si contents, decreases for P and Zr, and increases first then decreases for Ca and Ti. Above all, different matrix and U, Th and Pb amounts show distinct U/Pb and Th/Pb fractionations within ICPMS. The minerals with matrix indicating similar fractionations in ICPMS can be used as suitable reference standards for each other with proper laser ablation settings via LA-ICPMS. Moreover, matched U, Th and Pb contents should be considered when using a matrix-matched standard in laser ablation analysis.

Apatite-forming ability and mechanical properties of PTMO-modified CaO-SiO2-TiO2 hybrids derived from sol-gel processing.

PubMed

Miyata, Noboru; Fuke, Ken-ichi; Chen, Qi; Kawashita, Masakazu; Kokubo, Tadashi; Nakamura, Takashi

2004-01-01

Hydrolysis and polycondensation of triethoxysilane end-capped Poly (tetramethylene oxide) (Si-PTMO), tetraethoxysilane (TEOS), tetraisopropyltitanate (TiPT) and calcium nitrate (Ca(NO(3))(2)) gave transparent monolithics of PTMO-modified CaO-SiO(2)-TiO(2) hybrids. The samples with (TiPT)/(TEOS+TiPT) molar ratios from 0 to 0.20 under constant ratio of (Si-PTMO)/(TEOS+TiPT) of 2/3 in weight were prepared. It was found that the incorporation of TiO(2) component into a PTMO-CaO-SiO(2) hybrid results in an increase in the apatite-forming ability in a simulated body fluid: the hybrids with (TiPT)/(TEOS+TiPT) of 0.10 and 0.20 in mol formed an apatite on their surfaces within only 0.5 day. It seemed that, within the range of compositions studied, the TiO(2) content little affects the overall mechanical properties: Young's modulus were 52-55MPa, tensile strength, 7-9MPa, and strain at failure, about 30%. Thus, the organic-inorganic hybrids exhibiting both fairly high apatite-forming ability and high capability for deformation were obtained. These hybrid materials may be useful as new kind of bioactive bone-repairing materials.

Nanostructured microtubes based on TiO2 doped by Zr and Hf oxides with the anatase structure

NASA Astrophysics Data System (ADS)

Zheleznov, VV; Voit, EI; Sushkov, YV; Sarin, SA; Kuryavyi, VG; Opra, DP; Gnedenkov, SV; Sinebryukhov, SL; Sokolov, AA

2016-01-01

The nanostructured microtubes based on TiO2 have been prepared on the carbon fiber template using the sol-gel method. The microtubes consist of nanoparticles of metal oxides: TiO2/ZrO2 and TiO2/HfO2. The dependence of microtubes morphology and nanoparticles structure on the synthesis conditions has been studied using the methods of SEM, SAXS, and Raman spectroscopy. It has been demonstrated that at the stoichiometric ratio of up to 0.04 for Zr/Ti and up to 0.06 for Hf/Ti microtubes consist of uniform nanoparticles with the anatase structure. Along with further increase of the dopants content in the microtubes composition, nanoparticles acquire the core-shell structure. It has been suggested that nanoparticles have a core composed of the solid solutions Ti1-xZrxO2 or Ti1-xHfxO2 and a shell consisting of zirconium or hafnium titanate. The fabricated Zr- and Hf-doped TiO2 materials were investigated in view of their possible use as anode materials for Li-ion batteries. Charge- discharge measurements showed that the doped samples manifested significantly higher reversibility in comparison with the undoped TiO2. The method opens new prospects in synthesis of nanostructured materials for Li-ion batteries application.

Oxide Scales Formed on NiTi and NiPtTi Shape Memory Alloys

NASA Technical Reports Server (NTRS)

Smialek, James L.; Garg, Anita; Rogers, Richard B.; Noebe, Ronald D.

2011-01-01

Ni-49Ti and Ni-30Pt-50Ti (at.%) shape memory alloys were oxidized isothermally in air over the temperature range of 500 to 900 C. The microstructure, composition, and phase content of the scales were studied by SEM, EDS, XRD, and metallography. Extensive plan view SEM/EDS identified various features of intact or spalled scale surfaces. The outer surface of the scale was a relatively pure TiO2 rutile structure, typified by a distinct highly striated and faceted crystal morphology. Crystal size increased significantly with temperature. Spalled regions exhibited some porosity and less distinct features. More detailed information was obtained by correlation of SEM/EDS studies of 700 C/100 hr cross-sections with XRD analyses of serial or taper-polishing of plan surfaces. Overall, multiple layers exhibited graded mixtures of NiO, TiO2, NiTiO3, Ni(Ti) or Pt(Ni,Ti) metal dispersoids, Ni3Ti or Pt3Ti depletion zones, and substrate, in that order. The NiTi alloy contained a 3 at.% Fe impurity that appeared in embedded localized Fe-Ti-rich oxides, while the NiPtTi alloy contained a 2 v/o dispersion of TiC that appeared in lower layers. The oxidation kinetics of both alloys (in a previous report) indicated parabolic growth and an activation energy (250 kJ/mole) near those reported in other Ti and NiTi studies. This is generally consistent with TiO2 existing as the primary scale constituent, as described here.

Remote compositional mapping of lunar titanium and surface maturity

NASA Technical Reports Server (NTRS)

Johnson, J. R.; Larson, S. M.; Singer, Robert B.

1991-01-01

Lunar ilmenite (FeTiO3) is a potential resource capable of providing oxygen for life support and spacecraft propellant for future lunar bases. Estimates of TiO2 content in mature mare soils can be made using an empirical relation between the 400/500 nm reflectance ratio and TiO2 wt percent. A TiO2 abundance map was constructed for the entire near-side lunar maria accurate to + or - 2 wt percent TiO2 using CCD images obtained at the Tumamoc Hill 0.5 m telescope in Tucson, employing bandpass filters centered at 400 and 560 nm. Highest TiO2 regions in the maria are located in western Mare Tranquillitatis. Greater contrast differences between regions on the lunar surface can be obtained using 400/730 nm ratio images. The relation might well be refined to accommodate this possibly more sensitive indicator of TiO2 content. Another potential lunar resource is solar wind-implanted He-3 which may be used as a fuel for fusion reactors. Relative soil maturity, as determined by agglutinate content, can be estimated from 950/560 nm ration images. Immature soils appear darker in this ratio since such soils contain abundant pyroxene grains which cause strong absorption centered near 950 nm due Fe(2+) crystal field transitions. A positive correlation exists between the amount of He-3 and TiO2 content in lunar soils, suggesting that regions high in TiO2 should also be high in He-3. Reflectance spectrophotometry in the region 320 to 870 nm was also obtained for several regions. Below about 340 nm, these spectra show variations in relative reflectance that are caused by as yet unassigned near-UV absorptions due to compositional differences.

Al{sub 2}TiO{sub 5}-Al{sub 2}O{sub 3}-TiO{sub 2} nanocomposite: Structure, mechanical property and bioactivity studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalita, Samar Jyoti, E-mail: Samar.Kalita@und.nodak.edu; Somani, Vikas

2010-12-15

Novel biomaterials are of prime importance in tissue engineering. Here, we developed novel nanostructured Al{sub 2}TiO{sub 5}-Al{sub 2}O{sub 3}-TiO{sub 2} composite as a biomaterial for bone repair. Initially, nanocrystalline Al{sub 2}O{sub 3}-TiO{sub 2} composite powder was synthesized by a sol-gel process. The powder was cold compacted and sintered at 1300-1500 {sup o}C to develop nanostructured Al{sub 2}TiO{sub 5}-Al{sub 2}O{sub 3}-TiO{sub 2} composite. Nano features were retained in the sintered structures while the grains showed irregular morphology. The grain-growth and microcracking were prominent at higher sintering temperatures. X-ray diffraction peak intensity of {beta}-Al{sub 2}TiO{sub 5} increased with increasing temperature. {beta}-Al{sub 2}TiO{submore » 5} content increased from 91.67% at 1300 {sup o}C to 98.83% at 1500 {sup o}C, according to Rietveld refinement. The density of {beta}-Al{sub 2}TiO{sub 5} sintered at 1300 {sup o}C, 1400 {sup o}C and 1500 {sup o}C were computed to be 3.668 g cm{sup -3}, 3.685 g cm{sup -3} and 3.664 g cm{sup -3}, respectively. Nanocrystalline grains enhanced the flexural strength. The highest flexural strength of 43.2 MPa was achieved. Bioactivity and biomechanical properties were assessed in simulated body fluid. Electron microscopy confirmed the formation of apatite crystals on the surface of the nanocomposite. Spectroscopic analysis established the presence of Ca and P ions in the crystals. Results throw light on biocompatibility and bioactivity of {beta}-Al{sub 2}TiO{sub 5} phase, which has not been reported previously.« less

Effects of Alloying Elements on the Formation of Core-Shell-Structured Reinforcing Particles during Heating of Al-Ti Powder Compacts.

PubMed

Chen, Tijun; Gao, Min; Tong, Yunqi

2018-01-15

To prepare core-shell-structured Ti@compound particle (Ti@compound p ) reinforced Al matrix composite via powder thixoforming, the effects of alloying elements, such as Si, Cu, Mg, and Zn, on the reaction between Ti powders and Al melt, and the microstructure of the resulting reinforcements were investigated during heating of powder compacts at 993 K (720 °C). Simultaneously, the situations of the reinforcing particles in the corresponding semisolid compacts were also studied. Both thermodynamic analysis and experiment results all indicate that Si participated in the reaction and promoted the formation of Al-Ti-Si ternary compounds, while Cu, Mg, and Zn did not take part in the reaction and facilitated Al₃Ti phase to form to different degrees. The first-formed Al-Ti-Si ternary compound was τ1 phase, and then it gradually transformed into (Al,Si)₃Ti phase. The proportion and existing time of τ1 phase all increased as the Si content increased. In contrast, Mg had the largest, Cu had the least, and Si and Zn had an equivalent middle effect on accelerating the reaction. The thicker the reaction shell was, the larger the stress generated in the shell was, and thus the looser the shell microstructure was. The stress generated in (Al,Si)₃Ti phase was larger than that in τ1 phase, but smaller than that in Al₃Ti phase. So, the shells in the Al-Ti-Si system were more compact than those in the other systems, and Si element was beneficial to obtain thick and compact compound shells. Most of the above results were consistent to those in the semisolid state ones except the product phase constituents in the Al-Ti-Mg system and the reaction rate in the Al-Ti-Zn system. More importantly, the desirable core-shell structured Ti@compound p was only achieved in the semisolid Al-Ti-Si system.

The influence of carbon content on cyclic fatigue of NiTi SMA wires.

PubMed

Matheus, T C U; Menezes, W M M; Rigo, O D; Kabayama, L K; Viana, C S C; Otubo, J

2011-06-01

To evaluate two NiTi wires with different carbon and oxygen contents in terms of mechanical resistance to rotary bending fatigue (RBF) under varied parameters of strain amplitude and rotational speed. The wires produced from two vacuum induction melting (VIM) processed NiTi ingots were tested, Ti-49.81 at%Ni and Ti-50.33 at%Ni, named VIM 1 and VIM 2. A brief analysis related to wire fabrication is also presented, as well as chemical and microstructural analysis by energy dispersive spectroscopy (EDS) and optical microscope, respectively. A computer controlled RBF machine was specially constructed for the tests. Three radii of curvature were used: 50.0, 62.5 and 75.0 mm, respectively, R(1), R(2) and R(3), resulting in three strain amplitudes ε(a) : 1.00%, 0.80% and 0.67%. The selected rotational speeds were 250 and 455 rpm. The VIM 1 wire had a high carbon content of 0.188 wt% and a low oxygen content of 0.036 wt%. The oxygen and carbon contents of wire VIM 2 did not exceed their maximum, of 0.070 and 0.050 wt%, according to ASTM standard (ASTM F-2063-00 2001). The wire with lower carbon content performed better when compared to the one with higher carbon content, withstanding 29,441 and 12,895 cycles, respectively, to fracture. The surface quality of the wire was associated with resistance to cyclic fatigue. Surface defects acted as stress concentrators points. Overall, the number of cycles to failure was higher for VIM 2 wires with lower carbon content. © 2011 International Endodontic Journal.

Surface plasmon resonance effect of silver nanoparticles on a TiO2 electrode for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Jung, Haeng-Yun; Yeo, In-Seon; Kim, Tae-Un; Ki, Hyun-Chul; Gu, Hal-Bon

2018-02-01

In this study, we exploit local surface plasmon resonance (LSPR) in order to improve the efficiency of dye-sensitized solar cells (DSSCs). In order to investigate the effect of LSPR, Ag nanoparticles of several sizes were formed using electro-beam equipment; sizes were varied by changing the annealing time. DSSCs were fabricated by coating Ag nanoparticles onto a TiO2 thin film. Finally, TiO2 nanoparticles were layered onto the Ag nanoparticles via a titanium tetra-isopropoxide (TTIP) treatment. This study used nanoparticle-coated TiO2 thin films as photoelectrodes, and manufactured the cell in the unit of the DSSCs. We compared the behavior of the electrical properties of DSSCs depending on the presence or absence of Ag nanoparticles, as well as on the nanoparticle size. The Ag particles did not affect dye adsorption because the content of Ag particles is very low (0.13%) compared to that in TiO2 in the photoelectrode. The DSSCs with LSPR showed increased electric current density compared to those without LSPR, and improved the solar conversion efficiency (η) by 24%. The current density of the DSSCs increased because the light absorption of the dye increased. Therefore, we determined that LSPR affects the electrical properties of DSSCs.

Probing structural changes in Ca(1-x)Nd2x/3TiO3 ceramics by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Lowndes, Robert; Deluca, Marco; Azough, Feridoon; Freer, Robert

2013-01-01

Ceramics in the system Ca(1-x)Nd2x/3TiO3, intended for mobile communication applications, exhibit grossly non-linear variations in microwave dielectric properties with composition. There is evidence of a structural transition and the formation of vacancies on the A-site of the perovskite structure. High density, single phase perovskite Ca(1-x)Nd2x/3TiO3 ceramics have been prepared by the mixed oxide route. Raman spectroscopy was used to investigate the structural variations, which impact on dielectric properties. The Raman spectra show that with increasing Nd content, there is a transition from an ordered structure, to a disordered arrangement of cations and vacancies, and back to an ordered arrangement in Ca0.1Nd0.6TiO3. A structural phase transition from orthorhombic Pbnm to monoclinic C2/m coincides with the order-disorder transition at Ca0.1Nd0.6TiO3. Polarized Raman spectroscopy facilitated the assignment of the Raman modes and investigation of the role of importance of domain structures. Large variation in the plane angles was attributed to differences in domain structures. Differences in the angular dependence of the Raman modes with Nd content reflect changes in the preferred orientation of the domains from lamellar twins, to wedge shaped and back to lamellar twins.

Ti-in-Zircon Thermometer: Preliminary Results

NASA Astrophysics Data System (ADS)

Fu, B.; Cavosie, A. J.; Clechenko, C. C.; Fournelle, J.; Kita, N. T.; Lackey, J.; Page, F.; Wilde, S. A.; Valley, J. W.

2005-12-01

The titanium in zircon thermometer has been applied to 167 zircons from diverse rock types. These rocks include metamorphosed anorthosite and gabbro (1.15 Ga, intrusion age), and unmetamorphosed granitic pegmatite (0.9 Ga) from the Adirondack Highlands; metaluminous and peraluminous granites (114-90 Ma) of the Sierra Nevada Batholith; megacrysts from kimberlite pipes in southern Africa, Brazil, and Siberia; and detrital zircons (4.4-3.9 Ga) of metaconglomerate from Jack Hills, Western Australia. Titanium concentration in zircon was analysed using a CAMECA IMS-1280 ion microprobe (see Page et al., this volume). Spot analyses were correlated to U-Pb SHRIMP pits especially for Adirondack and Jack Hills zircons. The majority of zircons have Ti-content less than 10 ppm. Variability, in excess of analytical precision, within individual zircons is observed in about one-third of crystals. In general, there is no systematic change in Ti from core to rim (identified by cathodoluminescence) of zircons, or with regard to age, U content, Th/U ratio, or U-Pb age concordance for these non-metamict grains. The average temperatures for zircon crystallization in different rock suites using the experimental/empirical calibration of Watson and Harrison (W&H, 2005, Science 308:841), assuming the presence of rutile and quartz, are estimated to be: anorthosite 735±41°C (1SD, n=24; Ti = 10±5 ppm); metagabbro 714±31°C (n=19; Ti = 8±4 ppm); Adirondack pegmatite 500±16°C (n=5; Ti = 0.3±0.1 ppm); metaluminous and peraluminous granites from Sierra Nevada 681±67°C (n=53; Ti = 6±5 ppm) and 613±75°C (n=68; Ti = 3±3 ppm); kimberlite megacrysts 740±64°C (n=169; Ti = 14±13 ppm) (Page et al., this volume); and detrital zircons from Jack Hills metaconglomerate 718±63°C (n=64; Ti = 10±9 ppm). Most of the host rocks contain ilmenite or titanite suggesting that α(TiO2)>0.5, but rutile activity is unknown for megacrysts and detrital zircons. Pegmatite contains no Ti-rich minerals, permissive of low rutile activity. Peraluminous granites have lower whole-rock TiO2 content (0.02-0.21 wt.%) than metaluminous granites (0.54-0.91 wt.%), and both have similar zircon saturation temperatures (710-780°C). The low Ti content and apparent temperature in zircons from anorthosite and metagabbro (magmatic T = ca. 1000-1100°C) and the homogeneity of igneous zircon cores vs. metamorphic rims in metagabbro suggest that Ti content was reset during granulite-facies metamorphism (750°C, 1.0 Ga), in contrast to the current estimate of extremely low diffusivity of Ti in zircon. The Ti contents of >3.9 Ga Jack Hills detrital zircons are consistent with previously published data that were used to constrain magmatic temperature and thus the composition of unknown host rocks (W&H, 2005, Science 308:841). However, these values overlap those from both felsic and mafic rocks, and the Ti data are not sufficient to independently identify parent melt chemistry unless post-crystallization changes can be ruled out. The best evidence of pre-4 Ga evolved crust is provided by previously reported oxygen isotope ratios and felsic mineral inclusions in zircon (see Cavosie et al., 2005, EPSL 235:663).

Structure-property relationship of cast Ti-Nb alloys.

PubMed

Lee, C M; Ju, C P; Chern Lin, J H

2002-04-01

The present work is a study of the microstructure, mechanical properties and corrosion behaviour of a series of binary Ti-Nb alloys with Nb contents up to 35 wt%, with emphasis placed on the structure-property relationship of the alloys. The results indicate that crystal structure and morphology of the Ti-Nb alloys are sensitive to the Nb content. The cast c.p. Ti has a hexagonal alpha phase with a lath type morphology. The alloys containing 15 wt% or less Nb are dominated by a hexagonal alpha' phase with an acicular, martensitic structure. When containing 17.5-25 wt% Nb, the alloys are primarily comprised of an orthorhombic alpha" phase. With 27.5 wt% Nb, metastable beta phase starts to be retained. With Nb contents higher than 30 wt%, the equi-axed beta phase is almost entirely retained. Small amounts of omega phase are detected in alloys containing 27.5 and 30 wt% Nb. Among all present alloys, Ti-10Nb and Ti-27.5Nb exhibit the highest strengths, while the alpha"-dominated (17.5 and 20Nb) and beta-dominated (> 30Nb) alloys have the lowest moduli. All Ti-Nb alloys show excellent corrosion resistance in Hank's solution at 37 degrees C. From the present data, the microhardness, bending strength and modulus of the various phases in Ti-Nb alloys are compared and tentatively summarized as follows: Microhardness: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending strength: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending modulus: omega > alpha (c.p. Ti) > alpha' > alpha" > beta

Synthesis and characterization of AlTiSiN/CrSiN multilayer coatings by cathodic arc ion-plating

NASA Astrophysics Data System (ADS)

Yang, B.; Tian, C. X.; Wan, Q.; Yan, S. J.; Liu, H. D.; Wang, R. Y.; Li, Z. G.; Chen, Y. M.; Fu, D. J.

2014-09-01

AlTiSiN/CrSiN multilayer coatings were deposited on Si (1 0 0) and cemented carbide substrates using Cr, AlTi cathodes and SiH4 gases by cathodic arc ion plating system. The influences of SiH4 gases flowrate on the structural and mechanical properties of the coatings were investigated, systematically. AlTiSiN/CrSiN coatings exhibit a B1 NaCl-type nano-multilayered structure in which the CrSiN nano-layers alternate with AlTiSiN nano-layers with multiple orientations of crystal planes indicated by XRD patterns and TEM. Si contents of the coatings increase with increasing SiH4 flowrate. The hardness of the coatings increases to the maximum value of 3500 Hv0.05 with increasing SiH4 flowrate from 20 to 40 sccm and then decreases with further addition of SiH4 gases. A higher adhesive force of 73 N is obtained at the flowrate of 48 sccm. The coatings exhibit different tribological performance when the mating materials were varied from Si3N4 to cemented carbide balls and the variation of friction coefficients of the coatings against Si3N4 influenced by SiH4 flowrate are not obvious as against cemented carbide balls.

Characterizing Pyroxene Reaction Space in Calcium-Aluminum Rich Inclusions: Oxidation During CAI Rim Formation

NASA Astrophysics Data System (ADS)

Dyl, K. A.; Young, E. D.

2009-12-01

We define the reaction space that controls changes in pyroxene composition in CAIs and Wark-Lovering (WL) rims in an oxidizing solar nebula. Ti-rich pyroxenes in CAIs record a sub-solar oxygen fugacity (Ti3+/Ti4+~1.5). WL rim pyroxenes in the CAI Leoville 144A have a distinctly lower oxidation state.This difference supports WL rim condensation in an environment of increasing O2(g) and Mg(g) (Simon et al. 2005). We used the following phase components to identify four linearly independent reactions (Thompson 1982): diopside, CaTs (Al2Mg-1Si-1), T3 (Ti3+AlMg-1Si-1), T4 (Ti4+Al2Mg-1Si-2), En (MgCa-1), perovskite, O(g), Mg(g), SiO(g), and Ca(g). Compositional variation in this system is dominated by two reactions. The first is oxidation of Ti3+ via reaction with O and Mg in the gas phase: 1.5 O(g) + Mg(g) → ¼ Di + [Ti4+Mg3/4Ti3+-1Ca-1/4Si-1/2] (1). Pyroxene is produced and En is introduced. The second reaction (2) is perovskite formation. It is observed in the WL rim of Leoville 144A, and experiments confirm that an elevated Ti component converts pyroxene to perovskite(Gupta et al. 1973). MgCa-1 is the third linearly independent reaction (3). They combine to give: ½ Di + x Ca(g)→ x Mg(g)+ Pv + [Mg1/2-xSiTi4+-1Ca-1/2+x](2,3). Unlike (1), pyroxene is consumed in this reaction. The parameter x defines the extent of Mg-Ca exchange. When x > 0.5, WL rim formation occurs in an environment where Mg is volatile and Ca condenses. The reaction space defined by reactions (1) and (2,3) describes the transition from CAI interior to WL rims. WL rim pyroxene Ti contents, [CaTs], and Ca < 1 pfu are all explained in this space. The fourth linearly independent reaction is SiO(g):1/8 Di + ¼ Mg(g)→ ¾ SiO(g) + [Mg3/8Ca1/8Ti4+Ti3+-1Si-1/2](4). Silica reduction forms Ti4+, releasing SiO(g). (4) does not describe the oxidation of Ti3+ in WL rim pyroxene, but (1) - (4) results in En formation directly from the gas phase. This may explain WL rim analyses that have Si contents in excess of those predicted from reactions (1) and (2,3). Simon et al. (2005) EPSL 41, 272-283; Thompson (1982)Rev. Min. 10, 33-52; Gupta et al. (1973) Contr. Mineral. Petrol. 41, 333-344 Reaction space for CAI pyroxene. Pyroxenes plotted using titanium contents.

Valorization of titanium metal wastes as tanning agent used in leather industry.

PubMed

Crudu, Marian; Deselnicu, Viorica; Deselnicu, Dana Corina; Albu, Luminita

2014-10-01

The development of new tanning agents and new technologies in the leather sector is required to cope with the increasingly higher environmental pressure on the current tanning materials and processes such as tanning with chromium salts. In this paper, the use of titanium wastes (cuttings) resulting from the process of obtaining highly pure titanium (ingots), for the synthesis of new tanning agent and tanning bovine hides with new tanning agent, as alternative to tanning with chromium salts are investigated. For this purpose, Ti waste and Ti-based tanning agent were characterized for metal content by inductively coupled plasma mass spectrometry (ICP-MS) and chemical analysis; the tanned leather (wet white leather) was characterized by Scanning Electron Microscope/Energy Dispersive Using X-ray (Analysis). SEM/EDX analysis for metal content; Differential scanning calorimetric (DSC), Micro-Hot-Table and standard shrinkage temperature showing a hydrothermal stability (ranged from 75.3 to 77°C) and chemical analysis showing the leather is tanned and can be processed through the subsequent mechanical operations (splitting, shaving). On the other hand, an analysis of major minor trace substances from Ti-end waste (especially vanadium content) in new tanning agent and wet white leather (not detected) and residue stream was performed and showed that leachability of vanadium is acceptable. The results obtained show that new tanning agent obtained from Ti end waste can be used for tanning bovine hides, as eco-friendly alternative for chrome tanning. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of Mn and AlTiB Addition and Heattreatment on the Microstructures and Mechanical Properties of Al-Si-Fe-Cu-Zr Alloy.

PubMed

Yoo, Hyo-Sang; Kim, Yong-Ho; Lee, Seong-Hee; Son, Hyeon-Taek

2018-09-01

The microstructure and mechanical properties of as-extruded Al-0.1 wt%Si-0.2 wt%Fe- 0.4 wt%Cu-0.04 wt%Zr-xMn-xAlTiB (x = 1.0 wt%) alloys under various annealing processes were investigated and compared. After the as-cast billets were kept at 400 °C for 1 hr, hot extrusion was carried out with a reduction ratio of 38:1. In the case of the as-extruded Al-Si-Fe-Cu-Zr alloy at annealed at 620 °C, large equiaxed grain was observed. When the Mn content is 1.0 wt%, the phase exhibits a skeleton morphology, the phase formation in which Mn participated. Also, the volume fraction of the intermetallic compounds increased with Mn and AlTiB addition. For the Al-0.1Si-0.2Fe-0.4Cu-0.04Zr alloy with Mn and AlTiB addition from 1.0 wt%, the ultimate tensile strength increased from 100.47 to 119.41 to 110.49 MPa. The tensile strength of the as-extruded alloys improved with the addition of Mn and AlTiB due to the formation of Mn and AlTiB-containing intermetallic compounds.

Evolution of Microstructure and Mechanical Properties of Oxide Dispersion Strengthened Steels Made from Water-Atomized Ferritic Powder

NASA Astrophysics Data System (ADS)

Arkhurst, Barton Mensah; Kim, Jeoung Han

2018-05-01

Nano-structured oxide dispersion strengthened (ODS) steels produced from a 410L stainless steel powder prepared by water-atomization was studied. The influences of Ti content and milling time on the microstructure and the mechanical properties were analysed. It was found that the ODS steels made from the Si bearing 410L powder contained Y-Ti-O, Y-Ti-Si-O, Y-Si-O, and TiO2 oxides. Most nanoparticles produced after 80 h of milling were aggregated nanoparticles; however, after 160 h of milling, most aggregated nanoparticles dissociated into smaller individual nanoparticles. Perfect mixing of Y and Ti was not achieved even after the longer milling time of 160 h; instead, the longer hours of milling rather resulted in Si incorporation into the Y-Ti-O rich nanoparticles and a change in the matrix morphology from an equiaxed microstructure to a tempered martensite-like microstructure. The overall micro-hardness of the ODS steel increased with the increase of milling time. After 80 and 160 h, the microhardnesses were over 400 HV, which primarily resulted from the finer dispersed nanoparticles and in part to the formation of martensitic phases. Tensile strength of the 410L ODS steels was comparable with that of ODS steel produced from gas-atomized powder.

Effect of deposition parameters and heat-treatment on the microstructure, mechanical and electrochemical properties of hydroxyapatite/titanium coating deposited on Ti6Al4V by RF-magnetron sputtering

NASA Astrophysics Data System (ADS)

Qi, Jianwei; Chen, Zhangbo; Han, Wenjun; He, Danfeng; Yang, Yiming; Wang, Qingliang

2017-09-01

Functionally graded HA/Ti coatings were deposited on silicon and Ti6Al4V substrate by radio-frequency (RF) magnetron sputtering. The effect of RF-power, negative bias and heat-treatment on the microstructure, mechanical and electrochemical properties of the coatings were characterized by SEM, XRD, FTIR, AFM Nanoindentation and electrochemical workstation. The obtained results showed that the as-deposited HA/Ti coatings were characteristic of amorphous structure, which transformed into a crystal structure after heat-treatment, and reformed O-H peak. The content of crystallization was increasing with the increase of negative bias. A dense, homogenous, smooth and featured surface, and columnar cross-section structure was observed in SEM observation. AFM results showed that the surface roughness became higher after heat-treatment, and increased with increasing RF-power. The mechanical test indicated that the coating had a higher nanohardness (9.1 GPa) in the case of  -100 V and 250 W than that of Ti6Al4V substrate, and a critical load as high as 17  ±  3.5 N. The electrochemical test confirmed the HA/Ti coating served as a stable protecting barrier in improving the corrosion resistance, which the corrosion current density was 1.3% of Ti6Al4V, but it was significantly influenced by RF-power and negative bias. The contact angle test demonstrated that all the coatings exhibited favorable hydrophilic properties, and it decreased by 20-25% compared to that untreated samples. Thus all results indicated that magnetron sputtering is a promising way for fabricating a better biocompatible ceramic coating by adjusting deposition parameters and post-deposition heat treatments.

Simple fabrication of pineapple root-like palladium-gold catalysts as the high-efficiency cathode in direct peroxide-peroxide fuel cells.

PubMed

Wang, Xin; Ye, Ke; Sun, Ce; Zhang, Hongyu; Zhu, Kai; Cheng, Kui; Wang, Guiling; Cao, Dianxue

2017-07-15

Pd-Au/TiC electrodes with various three-dimensional structures are obtained by the pulsed potential electro-deposition in PdCl 2 /HAuCl 4 electrolytes. The morphologies of Pd-Au/TiC composite catalysts are significantly dependent on the component of deposited solutions. The surface appearance of Pd-Au catalysts changes from rime-shaped structure, to feather-like construction, then to pineapple root-like structure and finally to flower-like configuration with the increase of PdCl 2 content in electrolytes. These particular three-dimensional structures may be very suitable for H 2 O 2 electro-reduction, which assures a high utilization of Pd-Au catalysts and provides a large specific surface area. The electro-catalytic activities of H 2 O 2 reduction on the Pd-Au/TiC electrodes improve as increasing the Pd content in Pd-Au alloy catalysts. The pineapple root-like Pd 5 Au 1 /TiC electrode reveals remarkably excellent electrochemical property and desirable stability for catalyzing H 2 O 2 reduction in acid media. The direct peroxide-peroxide fuel cells with a 10 cm 3 min -1 flow rate display the open circuit voltage (OCV) of 0.85V and the peak power density of 56.5mWcm -2 at 155mAcm -2 with desirable cell stability, which is much higher than those previously reported. Copyright © 2017 Elsevier Inc. All rights reserved.

Origin of Fe-Ti Oxide Mineralization in the Middle Paleoproterozoic Elet'ozero Syenite-Gabbro Intrusive Complex (Northern Karelia, Russia)

NASA Astrophysics Data System (ADS)

Sharkov, E. V.; Chistyakov, A. V.; Shchiptsov, V. V.; Bogina, M. M.; Frolov, P. V.

2018-03-01

Magmatic oxide mineralization widely developed in syenite-gabbro intrusive complexes is an important Fe and Ti resource. However, its origin is hotly debatable. Some researchers believe that the oxide ores were formed through precipitation of dense Ti-magnetite in an initial ferrogabbroic magma (Bai et al., 2012), whereas others consider them as a product of immiscible splitting of Fe-rich liquid during crystallization of Fe-Ti basaltic magma (Zhou et al., 2013). We consider this problem with a study of the Middle Paleoproterozoic (2086 ± 30 Ma) Elet'ozero Ti-bearing layered intrusive complex in northern Karelia (Baltic Shield). The first ore-bearing phase of the complex is mainly made up of diverse ferrogabbros, with subordinate clinopyroxenites and peridotites. Fe-Ti oxides (magnetite, Ti-magnetite, and ilmenite) usually account for 10-15 vol %, reaching 30-70% in ore varieties. The second intrusive phase is formed by alkaline and nepheline syenites. Petrographical, mineralogical, and geochemical data indicate that the first phase of the intrusion was derived from a moderately alkaline Fe-Ti basaltic melt, while the parental melt of the second phase was close in composition to alkaline trachyte. The orebodies comprise disseminated and massive ores. The disseminated Fe-Ti oxide ores make up lenses and layers conformable to general layering. Massive ores occur in subordinate amounts as layers and lenses, as well as cross-cutting veins. Elevated Nb and Ta contents in Fe-Ti oxides makes it possible to consider them complex ores. It is shown that the Fe-Ti oxide mineralization is related to the formation of a residual (Fe,Ti)-rich liquid, which lasted for the entire solidification history of the first intrusive phase. The liquid originated through multiple enrichment of Fe and Ti in the crystallization zone of the intrusion owing to the following processes: (1) precipitation of silicate minerals in the crystallization zone with a corresponding increase in the Fe and Ti contents in an interstitial melt; and (2) periodic accumulation of the residual melt in front of this zone. Unlike liquid immiscibility leading to melt splitting into two phases, this liquid dissolved the residual components of the melt. Correspondingly, such an Fe-rich liquid has unusual properties and requires further study.

Impact of nano and bulk ZrO2, TiO2 particles on soil nutrient contents and PGPR.

PubMed

Karunakaran, Gopalu; Suriyaprabha, Rangaraj; Manivasakan, Palanisamy; Yuvakkumar, Rathinam; Rajendran, Venkatachalam; Kannan, Narayanasamy

2013-01-01

Currently, nanometal oxides are used extensively in different industries such as medicine, cosmetics and food. The increased consumption of nanoparticles (NPs) leads the necessity to understand the fate of the nanoparticles in the environment. The present study focused on the ecotoxicological behaviour of bulk and nano ZrO2 (Zirconia) and TiO2 (Titania) particles on PGPR (plant growth promoting rhizobacteria), soil and its nutrient contents. The microbial susceptibility study showed that nano TiO2 had 13 +/- 0.9 mm (B. megaterium), 15 +/- 0.2 mm (P. fluorescens), 16 +/- 0.2 mm (A. vinelandii) and 12 +/- 0.3 mm (B. brevis) zones of inhibition. However, nano and bulk ZrO2 particles were non-toxic to PGPR. In addition, it was found that toxicity varied depends on the medium of reaction. The soil study showed that nano TiO2 was found to be highly toxic, whereas bulk TiO2 was less toxic towards soil bacterial populations at 1000 mg L(-1). In contrast, nano and bulk ZrO2 were found to be inert at 1000 mg L(-1). The observed zeta potential and hydrophobicity of TiO2 particles causes more toxic than ZrO2 in parallel with particle size. However, nano TiO2 decreases the microbial population as well as nutrient level of the soil but not zirconia. Our finding shows that the mechanism of toxicity depends on size, hydrophobic potential and zeta potential of the metal oxide particles. Thus, it is necessary to take safety measures during the disposal and use of such toxic nanoparticles in the soil to prevent their hazardous effects.

Surface coating changes the physiological and biochemical impacts of nano-TiO2 in basil (Ocimum basilicum) plants.

PubMed

Tan, Wenjuan; Du, Wenchao; Barrios, Ana C; Armendariz, Raul; Zuverza-Mena, Nubia; Ji, Zhaoxia; Chang, Chong Hyun; Zink, Jeffrey I; Hernandez-Viezcas, Jose A; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

2017-03-01

Little is known about the effects of surface coating on the interaction of engineered nanoparticles (ENPs) with plants. In this study, basil (Ocimum basilicum) was cultivated for 65 days in soil amended with unmodified, hydrophobic (coated with aluminum oxide and dimethicone), and hydrophilic (coated with aluminum oxide and glycerol) titanium dioxide nanoparticles (nano-TiO 2 ) at 125, 250, 500, and 750 mg nano-TiO 2 kg -1 soil. ICP-OES/MS, SPAD meter, and UV/Vis spectrometry were used to determine Ti and essential elements in tissues, relative chlorophyll content, carbohydrates, and antioxidant response, respectively. Compared with control, hydrophobic and hydrophilic nano-TiO 2 significantly reduced seed germination by 41% and 59%, respectively, while unmodified and hydrophobic nano-TiO 2 significantly decreased shoot biomass by 31% and 37%, respectively (p ≤ 0.05). Roots exposed to hydrophobic particles at 750 mg kg -1 had 87% and 40% more Ti than the pristine and hydrophilic nano-TiO 2 ; however, no differences were found in shoots. The three types of particles affected the homeostasis of essential elements: at 500 mg kg - 1 , unmodified particles increased Cu (104%) and Fe (90%); hydrophilic increased Fe (90%); while hydrophobic increased Mn (339%) but reduced Ca (71%), Cu (58%), and P (40%). However, only hydrophobic particles significantly reduced root elongation by 53%. Unmodified, hydrophobic, and hydrophilic particles significantly reduced total sugar by 39%, 38%, and 66%, respectively, compared with control. Moreover, unmodified particles significantly decreased reducing sugar (34%), while hydrophobic particles significantly reduced starch (35%). Although the three particles affected basil plants, coated particles impacted the most its nutritional quality, since they altered more essential elements, starch, and reducing sugars. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of Grain Refinement and Cooling Rate on the Microstructure and Mechanical Properties of Secondary Al-Si-Cu Alloys

NASA Astrophysics Data System (ADS)

Timelli, Giulio; Camicia, Giordano; Ferraro, Stefano

2014-02-01

The effect of AlTi5B1 grain refinement and different solidification rates on metallurgical and mechanical properties of a secondary AlSi7Cu3Mg alloy is reported. While the Ti content ranges from 0.04 up to 0.225 wt.%, the cooling rate varies between 0.1 and 5.5 °C/s. Metallographic and thermal analysis techniques have been used to quantitatively examine the macro- and microstructural changes occurring with grain refiner addition at various cooling rates. The results indicate that a small AlTi5B1 addition produces the greatest refinement, while no significant reduction of grain size is obtained with a great amount of grain refiner. On increasing the cooling rate, a lower amount of AlTi5B1 master alloy is necessary to produce a uniform grain size throughout the casting. The combined addition of AlTi5B1 and Sr does not produce any reciprocal interaction or effect on primary α-Al and eutectic solidification. The grain refinement improves the plastic behavior of the alloy and increases the reliability of castings, as evidenced by the Weibull statistics.

Calcium titanium silicate based glass-ceramic for nuclear waste immobilisation

NASA Astrophysics Data System (ADS)

Sharma, K.; Srivastav, A. P.; Goswami, M.; Krishnan, Madangopal

2018-04-01

Titanate based ceramics (synroc) have been studied for immobilisation of nuclear wastes due to their high radiation and thermal stability. The aim of this study is to synthesis glass-ceramic with stable phases from alumino silicate glass composition and study the loading behavior of actinides in glass-ceramics. The effects of CaO and TiO2 addition on phase evolution and structural properties of alumino silicate based glasses with nominal composition x(10CaO-9TiO2)-y(10Na2O-5 Al2O3-56SiO2-10B2O3); where z = x/y = 1.4-1.8 are reported. The glasses are prepared by melt-quench technique and characterized for thermal and structural properties using DTA and Raman Spectroscopy. Glass transition and peak crystallization temperatures decrease with increase of CaO and TiO2 content, which implies the weakening of glass network and increased tendency of glasses towards crystallization. Sphene (CaTiSiO5) and perovskite (CaTiO3) crystalline phases are confirmed from XRD which are well known stable phase for conditioning of actinides. The microsturcture and elemental analysis indicate the presence of actinide in stable crystalline phases.

Small Molecules and Sum Frequency Generation Probes of Nanoparticulate TiO2

NASA Astrophysics Data System (ADS)

Shultz, Mary Jane

2006-03-01

Anatase TiO2 is known to photo catalytically mineralize a wide variety of pollutants and pathogens, both airborne and in aqueous solution. One of the major benefits of basing water treatment systems on TiO2 is that it is environmentally benign and so non toxic that it is used as a colorant in creamy salad dressing. The primary impediment to wide spread implementation of a TiO2 based system for water decontamination is that the quantum efficiency in contact with condense phase water is less than 5%. Since the quantum efficiency for destruction of airborne materials is greater than 80%, the potential for increased efficiency is very real. To convert the potential to practice, the oxidation mechanism needs to be more fully understood. We will report on the results of using a nonlinear optical spectroscopy, sum frequency generation (SFG) as an in situ probe of interactions at the TiO2 surface. Results suggest that the dominant oxidation mechanism converts from a direct to an indirect mechanism as the water content (vapor pressure) increases. This presentation will discuss the probe technique as well as the results.

Microstructure and wear resistance of Ti-Cu-N composite coating prepared via laser cladding/laser nitriding technology on Ti-6Al-4V alloy

NASA Astrophysics Data System (ADS)

Yang, Yuling; Cao, Shiyin; Zhang, Shuai; Xu, Chuan; Qin, Gaowu

2017-07-01

Ti-Cu-N coatings with three different Cu contents on Ti-6Al-4V alloy (TC4) were obtained via laser cladding together with laser nitriding (LC/LN) technology. Phase constituents, microstructure, microhardness, and wear resistance of the coatings were investigated. The evolution of the coefficients of friction for the three coatings was measured under dry sliding conditions as a function of the revolutions until the coating failure. The results show that the coatings are mainly composed of TiN, CuTi3 and some TiO6 phases dispersed in the matrix. A good metallurgical bonding between the coating and substrate has been successfully obtained. The prepared Ti-Cu-N composite coatings almost doubly enhance the microhardness of the TC4 alloy and reduce the friction down to 1/4-1/2 of the TC4 alloy, and thus significantly improve the wear resistance. The coefficient of friction depends on the Cu content in the coating.

Synthesis and Comparison of Two cBN Composites with Starting Ternary Carbide Binders

NASA Astrophysics Data System (ADS)

Yue, Zhenming; Yang, Limin; Gong, Jianhong; Gao, Jun

2018-04-01

Ti3SiC2 and Ti3AlC2 are two promising binders for the ultrahard composite polycrystalline cubic boron nitride (PcBN). In this study, the cBN composites with Ti3SiC2 and Ti3AlC2 binders with different binder contents were synthesized under the same high pressure ( 5.5 GPa) and high temperature (1350 °C) conditions. Their mechanical properties were measured separately, including Vickers hardness, bending hardening, and compression hardening. Together with XRD results, the phase compounds were also investigated. The decomposition and reaction processes were affected by binder content. Some new compounds formed during sintering, these compounds were TiC, TiSi2, SiC, TiB2, SiB4, TiB2, and TiC0.7N0.3 in Ti3SiC2-cBN composites, as well as TiC0.7N0.3, TiB2, and AlN in Ti3AlC2-cBN composites. The microstructure of the cracks surface was obtained after the bending tests, and was used to further investigate and compare their crack mode by SEM. The crack surface profile and elementary analysis on the oxidative surface were also discussed.

Laser engineered net shaping of quasi-continuous network microstructural TiB reinforced titanium matrix bulk composites: Microstructure and wear performance

NASA Astrophysics Data System (ADS)

Hu, Yingbin; Ning, Fuda; Wang, Hui; Cong, Weilong; Zhao, Bo

2018-02-01

Titanium (Ti) and its alloys have been successfully applied to the aeronautical and biomedical industries. However, their poor tribological properties restrict their fields of applications under severe wear conditions. Facing to these challenges, this study investigated TiB reinforced Ti matrix composites (TiB-TMCs), fabricated by in-situ laser engineered net shaping (LENS) process, through analyzing parts quality, microstructure formation mechanisms, microstructure characterizations, and workpiece wear performance. At high B content areas (original B particle locations), reaction between Ti and B particles took place, generating flower-like microstructure. At low B content areas, eutectic TiB nanofibers contacted with each other with the formation of crosslinking microstructure. The crosslinking microstructural TiB aggregated and connected at the boundaries of Ti grains, forming a three-dimensional quasi-continuous network microstructure. The results show that compared with commercially pure Ti bulk parts, the TiB-TMCs exhibited superior wear performance (i.e. indentation wear resistance and friction wear resistance) due to the present of TiB reinforcement and the innovative microstructures formed inside TiB-TMCs. In addition, the qualities of the fabricated parts were improved with fewer interior defects by optimizing laser power, thus rendering better wear performance.

Synthesis and Comparison of Two cBN Composites with Starting Ternary Carbide Binders

NASA Astrophysics Data System (ADS)

Yue, Zhenming; Yang, Limin; Gong, Jianhong; Gao, Jun

2018-05-01

Ti3SiC2 and Ti3AlC2 are two promising binders for the ultrahard composite polycrystalline cubic boron nitride (PcBN). In this study, the cBN composites with Ti3SiC2 and Ti3AlC2 binders with different binder contents were synthesized under the same high pressure ( 5.5 GPa) and high temperature (1350 °C) conditions. Their mechanical properties were measured separately, including Vickers hardness, bending hardening, and compression hardening. Together with XRD results, the phase compounds were also investigated. The decomposition and reaction processes were affected by binder content. Some new compounds formed during sintering, these compounds were TiC, TiSi2, SiC, TiB2, SiB4, TiB2, and TiC0.7N0.3 in Ti3SiC2-cBN composites, as well as TiC0.7N0.3, TiB2, and AlN in Ti3AlC2-cBN composites. The microstructure of the cracks surface was obtained after the bending tests, and was used to further investigate and compare their crack mode by SEM. The crack surface profile and elementary analysis on the oxidative surface were also discussed.

Wetting of TiC by Al-Cu alloys and interfacial characterization.

PubMed

Contreras, A

2007-07-01

The wetting behavior and the interfacial reactions that occurred between molten Al-Cu alloys (1, 4, 8, 20, 33, and 100 wt% Cu) and solid TiC substrates were studied by the sessile drop technique in the temperature range of 800-1130 degrees C. The effect of wetting behavior on the interfacial reaction layer was studied. All the Al-Cu alloys react with TiC at the interface forming an extensive reaction layer. The interface thickness varied with the samples, and depends on the temperature, chemical composition of the alloy and the time of the test. Wetting increases with increasing concentration of copper in the Al-Cu alloy at 800 and 900 degrees C. In contrast, at higher temperature such as 1000 degrees C wetting decreases with increasing copper content. The spreading kinetics and the work of adhesion were evaluated. The high values of activation energies indicated that spreading is not a simple viscosity controlled phenomenon but is a chemical reaction process. The spreading of the aluminum drop is observed to occur according to the formation of Al4C3, CuAl2O4, CuAl2, TiCux mainly, leading to a decreases in the contact angle. As the contact angle decreases the work of adhesion increases with increasing temperature. Al-Cu/TiC assemblies showed cohesive fracture corresponding to a strong interface. However, using pure Cu the adhesion work is poor, and the percentage of cohesion work is also too low (27-34%).

The Effect of MnO2 Content and Sintering Atmosphere on The Electrical Properties of Iron Titanium Oxide NTC Thermistors using Yarosite

NASA Astrophysics Data System (ADS)

Wiendartun; Gustaman Syarif, Dani

2017-02-01

The effect of MnO2 content and sintering atmosphere on the characteristics of Fe2TiO5 ceramics for Negative Thermal Coefficient (NTC) thermistors by using Fe2O3 derived from yarosite has been studied. The ceramics were produced by pressing a homogeneous mixture of Fe2O3, TiO2 and MnO2 (0-2.0 w/o) powders in appropriate proportions to produce Fe2TiO5 based ceramics and sintering the pressed powder at 1100-1200°C for 3 hours in air, O2 and N2 gas. Electrical characterization was done by measuring electrical resistivity of the sintered ceramics at various temperatures from 30°C to 200°C. Microstructure and structural analyses were also carried out by using an scanning electron microscope (SEM) and x-ray diffraction (XRD). The XRD data showed that the pellets crystallize in orthorhombic. The presence of second phase could not be identified from the XRD analyses. The SEM images showed that the grain size of pellet ceramics increase with increasing of MnO2 addition, and the grains size of the ceramic sintered in oxygen gas is smaller than sintered in nitrogen gas. Electrical data showed that the value of room temperature resistance (RRT) tend to decrease with respect to the increasing of MnO2 addition and the pellet ceramics sintered in oxygen gas had the largest thermistor constant (B), activation energy (Ea), sensitivity (α) and room temperature resistance (RRT), compared to the sintered in nitrogen gas. From the electrical characteristics data, it was known that the electrical characteristics of the Fe2TiO5 pellet ceramics followed the NTC characteristic. The fabricated Fe2TiO5 ceramics have thermistor constants (B = 2207-7145K). This can be applied as temperature sensor, and will fulfill the market requirement.

Nanoporous Aluminum Oxide Membranes Coated with Atomic Layer Deposition-Grown Titanium Dioxide for Biomedical Applications: An In Vitro Evaluation.

PubMed

Petrochenko, Peter E; Kumar, Girish; Fu, Wujun; Zhang, Qin; Zheng, Jiwen; Liang, Chengdu; Goering, Peter L; Narayan, Roger J

2015-12-01

The surface topographies of nanoporous anodic aluminum oxide (AAO) and titanium dioxide (TiO2) membranes have been shown to modulate cell response in orthopedic and skin wound repair applications. In this study, we: (1) demonstrate an improved atomic layer deposition (ALD) method for coating the porous structures of 20, 100, and 200 nm pore diameter AAO with nanometer-thick layers of TiO2 and (2) evaluate the effects of uncoated AAO and TiO2-coated AAO on cellular responses. The TiO2 coatings were deposited on the AAO membranes without compromising the openings of the nanoscale pores. The 20 nm TiO2-coated membranes showed the highest amount of initial protein adsorption via the micro bicinchoninic acid (micro-BCA) assay; all of the TiO2-coated membranes showed slightly higher protein adsorption than the uncoated control materials. Cell viability, proliferation, and inflammatory responses on the TiO2-coated AAO membranes showed no adverse outcomes. For all of the tested surfaces, normal increases in proliferation (DNA content) of L929 fibroblasts were observed over from 4 hours to 72 hours. No increases in TNF-alpha production were seen in RAW 264.7 macrophages grown on TiO2-coated AAO membranes compared to uncoated AAO membranes and tissue culture polystyrene (TCPS) surfaces. Both uncoated AAO membranes and TiO2-coated AAO membranes showed no significant effects on cell growth and inflammatory responses. The results suggest that TiO2-coated AAO may serve as a reasonable prototype material for the development of nanostructured wound repair devices and orthopedic implants.

Grindability of cast Ti-Cu alloys.

PubMed

Kikuchi, Masafumi; Takada, Yukyo; Kiyosue, Seigo; Yoda, Masanobu; Woldu, Margaret; Cai, Zhuo; Okuno, Osamu; Okabe, Toru

2003-07-01

The purpose of the present study was to evaluate the grindability of a series of cast Ti-Cu alloys in order to develop a titanium alloy with better grindability than commercially pure titanium (CP Ti), which is considered to be one of the most difficult metals to machine. Experimental Ti-Cu alloys (0.5, 1.0, 2.0, 5.0, and 10.0 mass% Cu) were made in an argon-arc melting furnace. Each alloy was cast into a magnesia mold using a centrifugal casting machine. Cast alloy slabs (3.5 mm x 8.5 mm x 30.5 mm), from which the hardened surface layer (250 microm) was removed, were ground using a SiC abrasive wheel on an electric handpiece at four circumferential speeds (500, 750, 1000, or 1250 m/min) at 0.98 N (100 gf). Grindability was evaluated by measuring the amount of metal volume removed after grinding for 1min. Data were compared to those for CP Ti and Ti-6Al-4V. For all speeds, Ti-10% Cu alloy exhibited the highest grindability. For the Ti-Cu alloys with a Cu content of 2% or less, the highest grindability corresponded to an intermediate speed. It was observed that the grindability increased with an increase in the Cu concentration compared to CP Ti, particularly for the 5 or 10% Cu alloys at a circumferential speed of 1000 m/min or above. By alloying with copper, the cast titanium exhibited better grindability at high speed. The continuous precipitation of Ti(2)Cu among the alpha-matrix grains made this material less ductile and facilitated more effective grinding because small broken segments more readily formed.

The effect of C content on the mechanical properties of Ti-Zr coatings.

PubMed

Rodríguez-Hernández, M G; Jiménez, O; Alvarado-Hernández, F; Flores, M; Andrade, E; Canto, C E; Ávila, C; Espinoza-Beltrán, F

2015-09-01

In this study, Ti-Zr and Ti-Zr-C coatings were deposited at room temperature via pulsed-DC magnetron sputtering. A 70Ti-30Zr at% target and a 99.99% graphite plate were used to deposit samples. In order to modify C content, coatings were deposited at different target powers such as 50, 75 and 100 W. Changes on the structure, microstructure and mechanical properties due to C addition were studied. Results indicate that the as-deposited coatings were partly crystalline and that an increment on C content stabilized α' phase and inhibited the appearance of ω precipitates. Therefore, Ti-Zr-C alloys with C>1.9 at% showed only α' phase whereas the others alloys exhibited α'+ω structures. Hardness values from 12.94 to 34.31 GPa were obtained, whereas the elastic modulus was found between 181.84 and 298 GPa. Finally, a high elastic recovery ratio (0.69-0.87) was observed as a function of composition. The overall properties of these coatings were improved due to C content increment, martensitic α' phase and nanocrystalline grain size (10-16 nm). Copyright © 2015 Elsevier Ltd. All rights reserved.

MOR vs SSZ origin of the Aladaǧ ophiolite (S-Turkey): implications from clinopyroxene geochemistry

NASA Astrophysics Data System (ADS)

Saka, Samet; Uysal, Ibrahim; Seitz, Michael; Melih Akmaz, Recep

2017-04-01

The Aladaǧ ophiolite is located in the eastern Taurides, north of the city of Adana, southern Turkey. From bottom to top it is composed of mantle peridotites, ultramafic-mafic cumulates, isotropic (massive) gabbro and diabase dykes. Mantle peridotites, represented by varying degrees of serpentinized dunite, harzburgite and lherzolite, are divided into two subgroups according to spinel Cr# and Lanthanum Group Element (LGE) contents. Group-1 mantle peridotites contain spinel with low Cr# [100×Cr/(Cr+Al) = 13-47] values and relatively high heavy LGE contents whereas Group-2 mantle peridotites contain spinel with relatively higher Cr# (44-74) values and lower heavy LGE contents. Clinopyroxene in the Aladaǧ mantle peridotites are diopside in composition. Clinopyroxenes from the Group-1 samples have TiO2 contents up to 0.37 wt.% and Na2O contents up to 0.89 wt.%. Conversely, the Group-2 clinopyroxenes were relatively depleted compared to the Group-1 clinopyroxenes in terms of TiO2 (<0,1 wt.%) and Na2O (<0.56 wt.%) contents. The Al2O3 contents are between 0.36-5.75 wt.% for the Group-1 clinopyroxenes and this value is relatively low and range between 0.06-2.68 wt.% for the Group-2 clinopyroxenes. Chondrite-normalized LGE patterns of clinopyroxene in the Group-1 and the Group-2 samples differ from each other. While the Group-1 clinopyroxenes show almost flat HLGE to MLGE patterns (DyN/LuN= 0.35-1.30 avg; 0.75), the Group-2 clinopyroxenes are represented by a more significant depletion from HLGE to MLGE (DyN/LuN= 0.04-0.41 avg; 0.19). Ti and Dy contents of clinopyroxene from the Group-1 samples range between 320-2536 ppm and 0.43-2.4 ppm, respectively. However, the Group-2 clinopyroxenes contain rather lower Ti and Dy contents compared to Group-1 clinopyroxenes, varying from 34 to 289 ppm and 0.02 to 0.20 ppm, respectively. The major oxide composition and LGE patterns as well as Ti and Dy contents of the clinopyroxenes indicate that Group-1 samples are relatively lower-degree partial melting residue left after melting in the mid-ocean ridges, while the Group-2 samples are higher degree partial melting residue at suprasubduction zone. The high Ti versus Dy and Zr contents of Group-1 clinopyroxenes support that they are dry melting residues at mid-ocean ridge setting; however, lower Ti contents for a given Zr contents of Group-2 clinopyroxenes imply that these clinopyroxenes are formed as a result of hydrous partial melting. This study was supported by #114Y094 TUBITAK project

Enhanced photocatalytic activity of electrospun nanofibrous TiO2/g-C3N4 heterojunction photocatalyst under simulated solar light

NASA Astrophysics Data System (ADS)

Wang, Chunlei; Hu, Liming; Chai, Bo; Yan, Juntao; Li, Jianfen

2018-02-01

Electrospun nanofibrous TiO2/g-C3N4 heterojunction photocatalysts with different TiO2 content have been synthesized via a facile electrospinning and subsequent in situ evaporation and calcination process for the first time, which are examined in terms of morphology, component content, optical properties, PL spectra, photocurrent response, EIS measurement, photocatalytic activity and mechanism. SEM images exhibit TiO2/g-C3N4-4 heterojunction photocatalyst possesses the excellent 1D structure. HRTEM and element mapping images confirm the formation of heterojunction structure. DRS tests identify that TiO2/g-C3N4-4 heterojunction exhibits the intensitive absorption in both UV and visible light region. The photoelectrochemical tests prove that the recombination between electrons and holes are effectively inhibited. Based on TG analysis and photodegradation experiments, TiO2/g-C3N4-4 heterojunction photocatalyst with TiO2 content of 29.30 wt% possesses the best photocatalytic degradation efficiency for the RhB among the g-C3N4, TiO2 and their mixture under simulated sunlight irradiation. Moreover, 1D morphology of TiO2/g-C3N4-4 heterojunction photocatalyst is in favor of separating from solution for reuse and transferring the electrons, and maintains a very high photocatalytic degradation efficiency of 96% even after four recycles experiments, which is beneficial for practical application.

Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications

PubMed Central

Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K.

2014-01-01

Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5–90 V), electrolyte temperature (10–50°C) and electrolyte NH4F content (0.025–0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0–1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15–70 nm) and length (45–1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants. PMID:25520180

Influence of Pb and La contents on the lattice configuration of La-substituted Pb(Zr,Ti)O3 films fabricated by CSD method.

PubMed

Shima, Hiromi; Nishida, Ken; Funakubo, Hiroshi; Iijima, Takashi; Katoda, Takashi; Naganuma, Hiroshi; Okamura, Soichiro

2009-04-01

The influence of Pb and La contents on the lattice configuration in La-substituted Pb(Zr0(.65),Ti0(.35))O3 (La- PZT) films was systematically investigated. La-PZT films with various La and Pb contents were fabricated on Pt/Ti/SiO(2)/Si substrates by chemical solution deposition (CSD). In the La- PZT films with a Pb content ratio of 125% relative to a stoichiometric value, La ions were substituted for not only A-site ions but also B-site ions at La contents greater than 3 mol%. La substitution for B-site seems to cause larger reduction of the unit cell size. In addition, we found that in the La-PZT films with a La content of 3 mol%, the Pb content of 116 mol% (120% relative to a stoichiometric value) was optimum from the viewpoint of site occupancy. This indicates that excess Pb prevented the A-site substitution of La ions.

Biopersistence and translocation to extrapulmonary organs of titanium dioxide nanoparticles after subacute inhalation exposure to aerosol in adult and elderly rats.

PubMed

Gaté, Laurent; Disdier, Clémence; Cosnier, Frédéric; Gagnaire, François; Devoy, Jérôme; Saba, Wadad; Brun, Emilie; Chalansonnet, Monique; Mabondzo, Aloise

2017-01-04

The increasing industrial use of nanoparticles (NPs) has raised concerns about their impact on human health. Since aging and exposure to environmental factors are linked to the risk for developing pathologies, we address the question of TiO 2 NPs toxicokinetics in the context of a realistic occupational exposure. We report the biodistribution of titanium in healthy young adults (12-13-week-old) and in elderly rats (19-month-old) exposed to 10mg/m 3 of a TiO 2 nanostructured aerosol 6h/day, 5days/week for 4 weeks. We measured Ti content in major organs using inductively coupled plasma mass spectrometry immediately and up to 180days after the end of exposure. Large amounts of titanium were initially found in lung which were slowly cleared during the post-exposure period. From day 28, a small increase of Ti was found in the spleen and liver of exposed young adult rats. Such an increase was however never found in their blood, kidneys or brain. In the elderly group, translocation to extra-pulmonary organs was significant at day 90. Ti recovered from the spleen and liver of exposed elderly rats was higher than in exposed young adults. These data suggest that TiO 2 NPs may translocate from the lung to extra-pulmonary organs where they could possibly promote systemic health effects. Copyright © 2016. Published by Elsevier Ireland Ltd.

Judd-Ofelt Parameters via Bayesian Inference

NASA Astrophysics Data System (ADS)

Silva, Valdeir A.; Silva, José W.; de Morais, Paulo C.; Dantas, Noelio O.

2018-04-01

Bayesian inference was used as a new approach to calculate of rare earth (RE) ion spectroscopic parameters within the Judd-Ofelt theory using the Li2O-B2O3-Al2O3 glass system doped with Nd2O3 and TiO2. This system was synthesized by the fusion method, and the physical properties of the as-synthesized material were investigated. Optical absorption, photoluminescence, micro-Raman, mass density, refractive index, and radiative lifetime calcuations were performed. We investigated the effects of crystal field changes on Nd3+-ions caused due to co-doping with increasing TiO2 content. We observed that co-doping with TiO2 altered the radiative transition rates A( J, J '), favored symmetry enhancement around the Nd3+-ions, and promoted the onset of vibrational modes, contributed to the attenuation of O-H bonds, and substantially increased the spectroscopic quality, χ.

Microstructure, mechanical behavior and biocompatibility of powder metallurgy Nb-Ti-Ta alloys as biomedical material.

PubMed

Liu, Jue; Chang, Lin; Liu, Hairong; Li, Yongsheng; Yang, Hailin; Ruan, Jianming

2017-02-01

Microstructures, mechanical properties, apatite-forming ability and in vitro experiments were studied for Nb-25Ti-xTa (x=10, 15, 20, 25, 35at.%) alloys fabricated by powder metallurgy. It is confirmed that the alloys could achieve a relative density over 80%. Meanwhile, the increase in Ta content enhances the tensile strength, elastic modulus and hardness of the as-sintered alloys. When increasing the sintering temperatures, the microstructure became more homogeneous for β phase, resulting in a decrease in the modulus and strength. Moreover, the alloys showed a good biocompatibility due to the absence of cytotoxic elements, and were suitable for apatite formation and cell adhesion. In conclusion, Nb-25Ti-xTa alloys are potentially useful in biomedical applications with their mechanical and biological properties being evaluated in this work. Copyright © 2016 Elsevier B.V. All rights reserved.

Calcium phosphate coatings modified with zinc- or copper- incorporation on Ti-40Nb alloy

NASA Astrophysics Data System (ADS)

Komarova, E. G.; Sedelnikova, M. B.; Sharkeev, Yu P.; Kazakbaeva, A. A.; Glukhov, I. A.; Khimich, M. A.

2017-05-01

The influence of the microarc oxidation parameters and electrolyte composition on the structure, properties and composition of CaP coatings modified with Zn- or Cu- incorporation on the Ti-40mas.%Nb (Ti-40Nb) alloy was investigated. The linear growth of thickness, roughness, and size of structural elements with process voltage increasing has been revealed. It was shown that the CaP coatings have the low contact angles with liquids and, consequently, high free surface energy. This indicates a high hydrophilicity of the coatings. X-ray diffraction analysis showed that the coatings have X-ray amorphous structure. The increase of the process voltage leads to the formation of such crystalline phases as CaHPO4 and β-Ca2P2O7 in the coatings. The maximum Ca/P atomic ratio was equal to 0.4, and Zn or Cu contents was equal to 0.3 or 0.2 at.%, respectively.

XAS study of TiO2-based nanomaterials

NASA Astrophysics Data System (ADS)

Schneider, K.; Zajac, D.; Sikora, M.; Kapusta, Cz.; Michalow-Mauke, K.; Graule, Th.; Rekas, M.

2015-07-01

X-Ray Absorption Spectroscopy studies of the W (0-1 at% W) and Mo-doped TiO2 (0-1 at% Mo) nanoparticle specimens at the K edges of titanium and molybdenum as well as at the L2 L3 edges of tungsten are presented. The materials were prepared with Flame Spray Synthesis process by oxidation of metal-organic precursors. The Ti:K edge spectra in the XANES range show pre-edge and post-edge features characteristic for anatase. A decrease of the amplitude of the EXAFS function with doping is observed and attributed to a softening of the crystal lattice. The Mo EXAFS functions show a considerable decrease of the second-neighbour-shell peak with increasing Mo content, which is attributed to an increased number of cation vacancies. For tungsten a less pronounced effect is observed. The Mo and W XANES spectra do not show noticeable changes with doping level, which indicates their unchanged oxidation states.

Deposition of TiOxNy Thin Films with Various Nitrogen Flow Rate:. Growth Behavior and Structural Properties

NASA Astrophysics Data System (ADS)

Cho, S.-J.; Jung, C.-K.; Bae, I.-S.; Song, Y.-H.; Boo, J.-H.

2011-06-01

We have deposited TiOxNy thin films on Si(100) substrates at 500 °C using RF PECVD system. Titanium iso-propoxide was used as precursor with different nitrogen flow rate to control oxygen and nitrogen contents in the films. Changes of chemical states of constituent elements in the deposited films were examined by XPS analysis. The data showed that with increasing nitrogen flow rate, the total amounts of nitrogen and titanium were increased while that of oxygen was decreased, resulting in a binding energy shift toward high energy side. The characteristics of film growth orientation and structure as well as morphology change behavior were also analyzed by XRD, TED, FT-IR, TEM, and SEM. Deposition at higher nitrogen flow rate results in finer clusters with a nanograin size and more effective photocatalytic TiOxNy thin films with hydrophilic surface.

Biocorrosion study of titanium-cobalt alloys.

PubMed

Chern Lin, J H; Lo, S J; Ju, C P

1995-05-01

The present work provides experimental results of corrosion behaviour in Hank's physiological solution and some other properties of in-house fabricated titanium-cobalt alloys with cobalt ranging from 25-30% in weight. X-ray diffraction (XRD) shows that, in water-quenched (WQ) alloys, beta-titanium is largely retained, whereas in furnace-cooled (FC) alloys, little beta-titanium is found. Hardness of the alloys increases with increasing cobalt content, ranging from 455 VHN for WQ Ti-25 wt% Co to 525 VHN for WQ Ti-30 wt% Co. Differential thermal analysis (DTA) indicates that melting temperatures of the alloys are lower than that of pure titanium by about 600 degrees C. Potentiodynamic polarization results show that all measured break-down potentials in Hank's solution at 37 degrees C are higher than 800 mV. The breakdown potential for the FC Ti-25 Wt% Co alloy is even as high as nearly 1200 mV.

Structural analysis and ferroelectric properties of Fe doped BaTiO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Ashutosh, E-mail: a.mansuri14@gmail.com, E-mail: amishra1960@yahoo.co.in; Mansuri, Amantulla, E-mail: a.mansuri14@gmail.com, E-mail: amishra1960@yahoo.co.in; Dwivedi, J. P.

2016-05-23

The polycrystalline samples of Fe doped BaTiO{sub 3} (BTO) with compositional formula BaTi{sub 1-x}Fe{sub x}O{sub 3} (x = 0, 0.03, 0.04 and 0.05) were prepared by solid-state reaction route. The influence of the Fe content on the structural, vibrational and electric properties of BaTiO{sub 3} was investigated using X-ray powder diffraction (XRD), Raman spectroscopy and Polarization techniques. XRD analysis indicates the formation of single-phase tetragonal structure for all the prepared samples. Tetragonal cubic structure with space group P4mm of all samples is further approved by Rietveld refinement. Room temperature Raman spectra of pure BaTiO{sub 3} show four active modes ofmore » vibration whose intensity decreases with increasing Fe doping. Small shift in Raman modes and increment in the line width has been observed with the doping ions. The hysteresis loop is very well performed with regular sharp characteristic of ferroelectric materials.« less

Effect of sintering temperature on the electrolysis of TiO2

NASA Astrophysics Data System (ADS)

Li, Ze-quan; Ru, Li-yue; Bai, Cheng-guang; Zhang, Na; Wang, Hai-hua

2012-07-01

The effects of sintering temperature on the microstructure and the conductivity of TiO2 cathodes were studied by examining the phase composition, microstructure, and element contents of the sintered cathodes and the cathodic products using X-ray diffraction and scanning electronic microscopy-energy dispersive spectrometry. The oxygen vacancy, conductivity, average pore diameter, and specific surface area of the sintered cathodes were detected by X-ray photoelectron spectroscopy, four-point probe, and ASPA 2010. The results showed that TiO2 phase transformations occurred, and oxygen vacancies formed with the increase of sintering temperature. The cathodic conductivity improved, but the average pore diameter and the effective response area of the TiO2 cathode were reduced when the sintering temperature increased. These phenomena could weaken the contact between reaction ions and electrons and also had the same effect on the cathodes and the molten salt. Moreover, they were disadvantageous to ion migration, so a lower sintering temperature was favorable for the microstructure of electrolysis. Consequently, the cathodic conductivity may be improved, but the microstructure became compact with the increase of sintering temperature. The cathodic products at different temperatures indicated that the cathodic conductivity was more important for electrolysis.

A multiproxy study between the Río de la Plata and the adjacent South-western Atlantic inner shelf to assess the sediment footprint of river vs. marineinfluence

NASA Astrophysics Data System (ADS)

Burone, Leticia; Ortega, Leonardo; Franco-Fraguas, Paula; Mahiques, Michel; García-Rodriguez, Felipe; Venturini, Natalia; Marin, Yamandú; Brugnoli, Ernesto; Nagai, Renata; Muniz, Pablo; Bícego, Marcia; Figueira, Rubens; Salaroli, Alexandre

2013-03-01

Proxies of terrigenous versus marine input (Al and Ti, Fe/Ca and Ti/Ca ratios), origin of organic matter (δ13C, δ15N and C/N ratio), productivity (Corg; Nt; CaCO3, P, Ca, and Ba content; and Ba/Al and Ba/Ti ratios), hydrodynamics (grain size, mean diameter and sorting) and biological records of the main features of the environment (benthic foraminifera assemblage distribution) were used to assess the sediment footprint of river vs. marine influence along the salinity gradient between the Rio de la Plata (RdlP) estuary and the adjacent South Western Atlantic Shelf. These criteria permitted characterisation and interpretation of the sedimentary processes influencing transition between three known environments: tidal river, estuarine and marine zones. Increases in sand and clay content at the transition between tidal river and proper estuarine zones indicate resuspension/deposition processes associated with the maximum turbidity zone (MTZ). The MTZ was also characterised by an increase in mixed organic matter content indicated by stable carbon and nitrogen isotope values, an increment in productivity proxies (Corg, Nt and CaCO3) and the substitution of the Miliammina fusca assemblage (brackish environments) for the Ammonia tepida assemblage (estuarine environments). The transition between estuarine and marine environments was characterised by a sharp (up to 99%) increase in sand content, reflecting the progradation of modern RdlP sediments toward relict continental shelf sediment. C/N values typical of the marine environment, decreased trace element concentrations and the distribution of the Buliminella elegantissima assemblage (a more marine assemblage) also highlight the marine environment. This paper is particularly important as a tool both to better understand sedimentological dynamics in salinity fronts (along the shelf sediment of large estuaries) and to elaborate more precise palaeoenvironmental and palaeoceanographic reconstructions.

The disclosed transformation of pre-sputtered Ti films into nanoparticles via controlled thermal oxidation

NASA Astrophysics Data System (ADS)

Awad, M. A.; Raaif, M.

2018-05-01

Nanoparticles of TiO2 were successfully prepared from pre-sputtered Ti films using the controlled thermal oxidation. The effect of oxidation temperature on structural, morphological and optical properties in addition to photocatalysis activity of the sputtered films was tested and explained. Analysis of XRD and EDAX elucidated the enhancement in crystallization and oxygen content with the increase of oxidation temperature. SEM depicted the formation of very fine nanoparticles with no specific border on the films oxidized at 550 and 600 °C, whilst crystallites with larger size of approximately from 16 to 23 nm have been observed for the film oxidized at 650 °C. Both optical transmission and refractive index were increased with increasing the oxidation temperature. A red shift in the absorption edge was obtained for the films oxidized at 650 °C compared to that oxidized at 600 °C. The photocatalysis tests demonstrated the priority of 600 °C nanoparticle films to decompose methyl orange (MO) more than 650 °C treated film.

Nitric acid passivation does not affect in vitro biocompatibility of titanium.

PubMed

Faria, Adriana C L; Beloti, Márcio M; Rosa, Adalberto L

2003-01-01

In general, both chemical composition and surface features of implants affect cell response. The aim of this study was to evaluate the effect of titanium (Ti) passivation on the response of rat bone marrow cells, considering cell attachment, cell morphology, cell proliferation, total protein content, alkaline phosphatase (ALP) activity, and bonelike nodule formation. Cells were cultured on both commercially pure titanium (cpTi) and titanium-aluminium-vanadium alloy (Ti-6Al-4V) discs, either passivated or not. For attachment evaluation, cells were cultured for 4 and 24 hours. Cell morphology was evaluated after 4 days. After 7, 14, and 21 days, cell proliferation, total protein content, and ALP activity were evaluated. Bonelike nodule formation was evaluated after 21 days. Data were compared by analysis of variance and the Duncan multiple range test. Cell attachment, cell morphology, cell proliferation, total protein content, ALP activity, and bonelike nodule formation all were unaffected by Ti composition or passivation. Although the protocol for passivation used here could interfere with the pattern of ions released from Ti-6Al-4V and cpTi surfaces, the present study did not show any effect of this surface treatment on in vitro biocompatibility of Ti as evaluated by osteoblast attachment, proliferation, and differentiation.

Effect of BiFeO3 doping on the structural, dielectric and electrical properties of CaCu3Ti4O12 ceramics

NASA Astrophysics Data System (ADS)

Dai, Haiyang; Liu, Dewei; Chen, Jing; Xue, Renzhong; Li, Tao; Xiang, Huiwen; Chen, Zhenping; Liu, Haizeng

2015-04-01

(1 - x)CaCu3Ti4O12- xBiFeO3 ( x = 0, 0.003, 0.006, 0.010 and 0.015) ceramics have been fabricated by the solid-state reaction method. The effects of BiFeO3 (BFO) doping on the microstructure, dielectric and electrical properties of CaCu3Ti4O12 (CCTO) ceramics were investigated. It is found that BFO doping can affect the microstructure of the CCTO ceramics, and some properties of CCTO ceramics can hence be improved by BFO doping. The XRD and Raman results show that no phase transition has occurred in the doping content range, but BFO doping induces the crystal structure distortion. Analysis of microstructure indicates that the grain morphology varies significantly with increasing BFO content, and an appropriate amount of BFO can promote the grain growth. Impedance spectroscopy results show that the dielectric constant and loss of the BFO-doped CCTO samples are stable with frequency. The dielectric constant and nonohmic properties can be enhanced markedly in an appropriate doping content. The dielectric loss of all BFO-doped samples was lower than that of undoped CCTO sample in low frequencies. The related mechanism is also discussed in the paper.

Lightweight Mg-based composites with thermodynamically stable interfaces by in-situ combustion synthesis

NASA Astrophysics Data System (ADS)

Jo, Ilguk

Lightweight Mg-based composites have been produced by in-situ combustion synthesis of the Al-Ti-C reaction system. The characteristics of the in-situ composites were investigated in terms of phase evolution and interfacial stability using various analysis techniques. The structural analysis results showed that full conversion of the Al-Ti-C reactants into spherical TiC reinforcements with sizes around 1mum was achieved by the combustion reaction. In-situ formed TiC had less oxygen and higher Al contents at the interface than ex-situ formed TiC; these clean interfaces with an Al layer on the reinforcements were shown to yield interfacial stability. For these reasons, the in-situ composites exhibited higher theoretical densities and also good mechanical properties compared with ex-situ produced composites. The interfacial characteristics of molten Mg with the Al-Ti-C reactants and the commercial TiC+Al substrates were evaluated using an infiltration technique under an argon atmosphere. Infiltration length increased with time at temperature, yielding activation energies (Ea) for each system. The value of Ea for the Al-Ti-C system (307.31kJ/mol) is lower than that for the other system (350.84kJ/mol); the high Ea value indicates that the infiltration is not a simple viscosity-controlled phenomenon but involves a chemical reaction. Formation of the Al3Ti phase was observed from the crystal structural analysis of the infiltrated area; thus, existence of reaction promoting the wetting of Mg. The phase evolution, reaction mechanism and kinetics of the Al-Ti-C reaction were studied using DSC and HT-XRD. It was confirmed that, along with the melting of Al, there was formation of Al3Ti by reaction between Al and Ti. A detailed structural analysis indicates that, the reaction mechanism involves melting of Al followed by formation and growth of Al 3Ti, which then contacts the graphite powder and initiates the combustion reaction. The effect of important process parameters, such as the Al content and the reactant sizes, on the microstructure of the resulting in-situ composites is discussed. Feasibility and castability of the composites were investigated by high pressure die casting the composite preforms into automotive parts and durability tests were conducted on the cast parts.

Aluminum exclusion from root zone and maintenance of nutrient uptake are principal mechanisms of Al tolerance in Pisum sativum L.

PubMed

Kichigina, Natalia E; Puhalsky, Jan V; Shaposhnikov, Aleksander I; Azarova, Tatiana S; Makarova, Natalia M; Loskutov, Svyatoslav I; Safronova, Vera I; Tikhonovich, Igor A; Vishnyakova, Margarita A; Semenova, Elena V; Kosareva, Irina A; Belimov, Andrey A

2017-10-01

Our study aimed to evaluate intraspecific variability of pea ( Pisum sativum L.) in Al tolerance and to reveal mechanisms underlying genotypic differences in this trait. At the first stage, 106 pea genotypes were screened for Al tolerance using root re-elongation assay based on staining with eriochrome cyanine R. The root re-elongation zone varied from 0.5 mm to 14 mm and relationships between Al tolerance and provenance or phenotypic traits of genotypes were found. Tolerance index (TI), calculated as a biomass ratio of Al-treated and non-treated contrasting genotypes grown in hydroponics for 10 days, varied from 30% to 92% for roots and from 38% to 90% for shoots. TI did not correlate with root or shoot Al content, but correlated positively with increasing pH and negatively with residual Al concentration in nutrient solution in the end of experiments. Root exudation of organic acid anions (mostly acetate, citrate, lactate, pyroglutamate, pyruvate and succinate) significantly increased in several Al-treated genotypes, but did not correlate with TI. Al-treatment decreased Ca, Co, Cu, K, Mg, Mn, Mo, Ni, S and Zn contents in roots and/or shoots, whereas contents of several elements (P, B, Fe and Mo in roots and B and Fe in shoots) increased, suggesting that Al toxicity induced substantial disturbances in uptake and translocation of nutrients. Nutritional disturbances were more pronounced in Al sensitive genotypes. In conclusion, pea has a high intraspecific variability in Al tolerance and this trait is associated with provenance and phenotypic properties of plants. Transformation of Al to unavailable (insoluble) forms in the root zone and the ability to maintain nutrient uptake are considered to be important mechanisms of Al tolerance in this plant species.

Zn2+ in-situ substitution behavior during the formation of BaTiO3 coatings from plasma-sprayed powders collected in liquid nitrogen

NASA Astrophysics Data System (ADS)

Liu, Zhe; Xing, Zhiguo; Wang, Haidou; Xue, Zifan; Chen, Shuying; Cui, Xiufang; Jin, Guo

2018-04-01

The dielectric performance of BaTiO3 ceramic coatings is enhanced significantly by the addition of ZnO. In this study, the maximum relative permittivity value (εr ≈ 923) was measured in BaTiO3 coatings with ZnO added at 6 wt%. The Curie temperature (Tc) was in the range of 111 °C-121 °C for all of the ZnO-modified BaTiO3 coatings. Tc shifted to low temperatures as the ZnO content increased. Detailed analyses were performed to determine the phase composition and optical band gaps of powders collected in liquid nitrogen, which showed that the Zn2+ ions were incorporated into the BaTiO3 lattice where they substituted into the Ti4+ sites, and the composite powders (BaTiO3 + 6 wt% ZnO) tolerated high temperatures in the plasma beam. In addition, some residual Zn accumulated in the grain boundary in the form of ZnO. X-ray diffraction and Raman spectroscopy showed that the substitution led to changes in the compositional and structural properties. The red shift in the optical band gap of BaTiO3 indicated that the ZnTi'' defects caused by the dopants acted as carriers in the doped BaTiO3 coatings.

Photocatalytic removal of SO2 using natural zeolite modified by TiO2 and polyoxypropylene surfactant.

PubMed

Amini, Nasibeh; Soleimani, Mohsen; Mirghaffari, Nourollah

2018-01-25

Air pollution due to emission of various hazardous gases such as SO 2 into the atmosphere and its control is an important environmental issue. Application of photocatalysts is considered as a suitable process to control the gaseous pollutants. In this study, the efficiency of clinoptilolite as a natural zeolite (Ze) modified by TiO 2 (Ze-Ti) and a polymeric surfactant polyoxypropylene (Ze-Ti-POP) for removal of SO 2 was investigated. The nanocomposites were characterized by SEM, EDX, and BET analyses. The photocatalytic oxidation experiments of SO 2 by the nanocomposites and natural zeolite were done under UV irradiation with initial SO 2 concentration of 500 ppm in a photoreactor. The effects of different factors including reaction time, catalyst dose, UV irradiation intensity, humidity content, and calcination temperature and dose of TiO 2 were studied. The modification of clinoptilolite by TiO 2 and POP increased considerably the BET specific surface area of the nanocomposites. The results showed that maximum removal efficiencies of SO 2 by Ze-Ti and Ze-Ti-POP under the optimum experimental conditions were 82.1 and 87.4%, respectively. Adsorption kinetics data well fitted with the Langmuir-Hinshelwood model. Moreover, reusing of nanocomposites after three regeneration cycles indicated that application of Ze-Ti and Ze-Ti-POP nanocomposites could be a promising approach for SO 2 removal. Graphical abstract ᅟ.

CdSe nanorod/TiO2 nanoparticle heterojunctions with enhanced solar- and visible-light photocatalytic activity

PubMed Central

Laatar, Fakher; Moussa, Hatem; Alem, Halima; Balan, Lavinia; Girot, Emilien; Medjahdi, Ghouti; Ezzaouia, Hatem

2017-01-01

CdSe nanorods (NRs) with an average length of ≈120 nm were prepared by a solvothermal process and associated to TiO2 nanoparticles (Aeroxide® P25) by annealing at 300 °C for 1 h. The content of CdSe NRs in CdSe/TiO2 composites was varied from 0.5 to 5 wt %. The CdSe/TiO2 heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV–visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO2 particles. The UV–visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO2 composites until ≈725 nm. The CdSe (2 wt %)/TiO2 composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO2 and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO2. Due to its high stability (up to ten reuses without any significant loss in activity), the CdSe/TiO2 heterostructured catalysts show high potential for real water decontamination. PMID:29354345

CdSe nanorod/TiO2 nanoparticle heterojunctions with enhanced solar- and visible-light photocatalytic activity.

PubMed

Laatar, Fakher; Moussa, Hatem; Alem, Halima; Balan, Lavinia; Girot, Emilien; Medjahdi, Ghouti; Ezzaouia, Hatem; Schneider, Raphaël

2017-01-01

CdSe nanorods (NRs) with an average length of ≈120 nm were prepared by a solvothermal process and associated to TiO 2 nanoparticles (Aeroxide ® P25) by annealing at 300 °C for 1 h. The content of CdSe NRs in CdSe/TiO 2 composites was varied from 0.5 to 5 wt %. The CdSe/TiO 2 heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV-visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO 2 particles. The UV-visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO 2 composites until ≈725 nm. The CdSe (2 wt %)/TiO 2 composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO 2 and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO 2 . Due to its high stability (up to ten reuses without any significant loss in activity), the CdSe/TiO 2 heterostructured catalysts show high potential for real water decontamination.

Phase transformation in (0.90- x)Pb(Mg 1/3Nb 2/3)O 3- xPbTiO 3-0.10PbZrO 3 piezoelectric ceramic: X-ray diffraction and Raman investigation

NASA Astrophysics Data System (ADS)

Xia, Zhiguo; Li, Qiang

2007-05-01

Piezoelectric ceramics with compositions of (0.90- x)Pb(Mg 1/3Nb 2/3)O 3- xPbTiO 3-0.10PbZrO 3, x=0.28, 0.31, 0.34, 0.37, 0.40 and 0.43, were prepared using the conventional columbite precursor method, and their structural phase transformation and piezoelectric behaviors near the morphotropic phase boundary (MPB) have been systematically investigated as a function of PbTiO 3 content. X-ray diffraction (XRD) results demonstrate that the structure of the ceramics experiences a gradual transition process from rhombohedral phase to tetragonal phase with the increasing of PbTiO 3 content, and that compositions with x=0.34-0.40 lie in the MPB region of this ternary system. A Raman spectra investigation of the ceramic samples testified to the transformation process of rhombohedral phase to tetragonal phase by comparing the relative intensities of tetragonal E(2TO 1) mode and rhombohedral phase R h mode. The structure information was also correlated to the parabola change of the piezoelectric constant; the maximum piezoelectric constants were obtained near the MPB region.

Hemp (Cannabis sativa L.) as an Environmentally Friendly Energyplant

NASA Astrophysics Data System (ADS)

Poisa, Liena; Adamovics, Aleksandrs

2010-01-01

Hemp is suitable as a renewable energy resource. The aim of this study was to clarify local hemp's (Cannabis sativa L.) possibilities for energy use. Arsenic (As), cadmium (Cd), lead (Pb) and titanium (Ti) presence in hemp was determined using an inductively coupled plasma optical emission spectrometer Optima 2100 DV. If there were increased N fertilizer rates, there were increased hemp `Pūriņi' seeds and shive yield increases, but the oil content was reduced. Arsenic content was higher in the shives than in the stems with fibre. The ash content depends on non-organic substances which the plants absorb during the vegetation season. The lignin content depends on several factors: plant parts, and the N fertilizer rate. The unexplored factors have a great effect on the ash and lignin content. Hemp is suitable for cultivation and for bio-energy production in the agro-climatic conditions in Latvia.

Effect of Spray Distance on Microstructure and Tribological Performance of Suspension Plasma-Sprayed Hydroxyapatite-Titania Composite Coatings

NASA Astrophysics Data System (ADS)

Zhang, Chao; Xu, Haifeng; Geng, Xin; Wang, Jingjing; Xiao, Jinkun; Zhu, Peizhi

2016-10-01

Hydroxyapatite (HA)-titania (TiO2) composite coatings prepared on Ti6Al4V alloy surface can combine the excellent mechanical property of the alloy substrate and the good biocompatibility of the coating material. In this paper, HA-TiO2 composite coatings were deposited on Ti6Al4V substrates using suspension plasma spray (SPS). X-ray diffraction, scanning electron microscopy, Fourier infrared absorption spectrometry and friction tests were used to analyze the microstructure and tribological properties of the obtained coatings. The results showed that the spray distance had an important influence on coating microstructure and tribological performance. The amount of decomposition phases decreased as the spray distance increased. The increase in spray distance from 80 to 110 mm improved the crystalline HA content and decreased the wear performance of the SPS coatings. In addition, the spray distance had a big effect on the coating morphology due to different substrate temperature resulting from different spray distance. Furthermore, a significant presence of OH- and CO3 2- was observed, which was favorable for the biomedical applications.

Effect of carbide additions on grain growth in TiC-Ni cermets

NASA Astrophysics Data System (ADS)

Shin, Soon-Gi; Lee, Jun-Hee

2006-02-01

The growth of carbide particles in TiC-XC-2 vol.% Ni and TiC-XC-30 vol.% Ni alloys, where X=Zr, Cr, W, Ta and Mo, was fitted to an equation of the form d3-do 3=Kt. The grain growth behavior during liquid phase sintering at 1673K decreased markedly with the addition of Mo2C or WC, changed little for TaC, and increased with the addition of ZrC or Cr3C2. The grain contiguity decreased with increasing Ni content in the TiC-Mo2C-Ni alloy and was greater in the alloys with smaller growth rate constant. Consequently, the effect of carbide addition on the grain growth of 2 vol.% Ni alloys was found to be similar to that of 30 vol.% Ni alloys. The grain growth mechanism could be explained by the effect of contiguous carbide grain boundaries in restricting the overall grain growth, as well as the area of the solid/liquid interfaces in the alloy by the usual solution/reprecipitation model.

Crystallization of baria-titania-silica glasses

NASA Technical Reports Server (NTRS)

Ray, Chandra S.; Day, Delbert E.

1986-01-01

The critical cooling rate for glass formation, Rc, and the crystallization kinetics of the compositions (1/2)(100-x)BaO-(1/2)(100-x)TiO2-(x)SiO2 with x = 20, 25, 30, 33.3, and 40 mol pct were studied using a thermal image furnace. Crystallization was studied under nonisothermal conditions, and the data were analyzed using the Johnson-Mehl-Avrami equation. The Rc and activation energy for crystallization both decrease with increasing silica content. Fresnoite, Ba2TiSi2O8, crystallized from all of the glasses when they were reheated. The infrared absorption spectra of the glasses and crystals show that they both contain (Si2O7) and square pyramidal (TiO5) groups.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, D.J.; Pask, J.A.

The sintering of TiC-Ni particle compacts was studied with specific attention to effects of processing conditions. Densification was progressively inhibited with the increasing additions of free carbon to the system. These results are explained on the basis of changes in the eutectic reactions in the system, reduced solubility of TiC in the Ni-rich liquid, and decreased wetting of the solid by the liquid. Presintering hydrogen heat treatment reduced the carbon content of the TiC-Ni compacts and led to reduction in sintering rates and elevated temperatures of liquid-phase formation. Wetting experiments with hydrogen-treated materials showed a time-dependent wetting angle. These resultsmore » are discussed based on wetting theory and reactions predicted by the equilibrium ternary-phase diagram.« less

Growth, Structure, and Photocatalytic Properties of Hierarchical V₂O₅-TiO₂ Nanotube Arrays Obtained from the One-step Anodic Oxidation of Ti-V Alloys.

PubMed

Nevárez-Martínez, María C; Mazierski, Paweł; Kobylański, Marek P; Szczepańska, Grażyna; Trykowski, Grzegorz; Malankowska, Anna; Kozak, Magda; Espinoza-Montero, Patricio J; Zaleska-Medynska, Adriana

2017-04-05

V₂O₅-TiO₂ mixed oxide nanotube (NT) layers were successfully prepared via the one-step anodization of Ti-V alloys. The obtained samples were characterized by scanning electron microscopy (SEM), UV-Vis absorption, photoluminescence spectroscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (DRX), and micro-Raman spectroscopy. The effect of the applied voltage (30-50 V), vanadium content (5-15 wt %) in the alloy, and water content (2-10 vol %) in an ethylene glycol-based electrolyte was studied systematically to determine their influence on the morphology, and for the first-time, on the photocatalytic properties of these nanomaterials. The morphology of the samples varied from sponge-like to highly-organized nanotubular structures. The vanadium content in the alloy was found to have the highest influence on the morphology and the sample with the lowest vanadium content (5 wt %) exhibited the best auto-alignment and self-organization (length = 1 μm, diameter = 86 nm and wall thickness = 11 nm). Additionally, a probable growth mechanism of V₂O₅-TiO₂ nanotubes (NTs) over the Ti-V alloys was presented. Toluene, in the gas phase, was effectively removed through photodegradation under visible light (LEDs, λ max = 465 nm) in the presence of the modified TiO₂ nanostructures. The highest degradation value was 35% after 60 min of irradiation. V₂O₅ species were ascribed as the main structures responsible for the generation of photoactive e - and h⁺ under Vis light and a possible excitation mechanism was proposed.

Crystallization and Martensitic Transformation Behavior of Ti-Ni-Si Alloy Ribbons Prepared via Melt Spinning.

PubMed

Park, Ju-Wan; Kim, Yeon-Wook; Nam, Tae-Hyun

2018-09-01

Ti-(50-x)Ni-xSi (at%) (x = 0.5, 1.0, 3.0, 5.0) alloy ribbons were prepared via melt spinning and their crystallization procedure and transformation behavior were investigated using differential scanning calorimtry, X-ray diffraction, and transmission electron microscopy. Ti-Ni-Si alloy ribbons with Si content less than 1.0 at% were crystalline, whereas those with Si content more than 3.0 at% were amorphous. Crystallization occurred in the sequence of amorphous →B2 → B2 → Ti5Si4 + TiNi3 → B2 + Ti5Si4 + TiNi3 + TiSi in the Ti-47.0Ni-3.0Si alloy and amorphous →R → R + Ti5Si4 + TiNi3 → R + Ti5Si4 + TiNi3 + TiSi in the Ti-45.0Ni-5.0Si alloy. The activation energy for crystallization was 189 ±8.6 kJ/mol for the Ti-47Ni-3Si alloy and 212±8.6 kJ/mol for the Ti-45Ni-5Si alloy. One-stage B2-R transformation behavior was observed in Ti-49.5Ni-0.5Si, Ti-49.0Ni-1.0Si, and Ti-47.0Ni- 3.0Si alloy ribbons after heating to various temperatures in the range of 873 K to 1073 K. In the Ti-45.0Ni-5.0Si alloy, one-stage B2-R transformation occurred after heating to 893 K, two-stage B2-R-B19' occurred after heating to 973 K, and two-stage B2-R-B19' occurred on cooling and one-stage B19'-B2 occurred on heating, after heating to 1073 K.

Ultra-porous titanium oxide scaffold with high compressive strength

PubMed Central

Tiainen, Hanna; Lyngstadaas, S. Petter; Ellingsen, Jan Eirik

2010-01-01

Highly porous and well interconnected titanium dioxide (TiO2) scaffolds with compressive strength above 2.5 MPa were fabricated without compromising the desired pore architectural characteristics, such as high porosity, appropriate pore size, surface-to-volume ratio, and interconnectivity. Processing parameters and pore architectural characteristics were investigated in order to identify the key processing steps and morphological properties that contributed to the enhanced strength of the scaffolds. Cleaning of the TiO2 raw powder removed phosphates but introduced sodium into the powder, which was suggested to decrease the slurry stability. Strong correlation was found between compressive strength and both replication times and solid content in the ceramic slurry. Increase in the solid content resulted in more favourable sponge loading, which was achieved due to the more suitable rheological properties of the ceramic slurry. Repeated replication process induced only negligible changes in the pore architectural parameters indicating a reduced flaw size in the scaffold struts. The fabricated TiO2 scaffolds show great promise as load-bearing bone scaffolds for applications where moderate mechanical support is required. PMID:20711636

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stengl, Vaclav, E-mail: stengl@iic.cas.cz; Bludska, Jana; Oplustil, Frantisek

Highlights: {yields} New nano-dispersive materials for warfare agents decontamination. {yields} 95% decontamination activities for sulphur mustard. {yields} New materials base on titanium and manganese oxides. -- Abstract: Titanium(IV)-manganese(IV) nano-dispersed oxides were prepared by a homogeneous hydrolysis of potassium permanganate and titanium(IV) oxo-sulphate with 2-chloroacetamide. Synthesised samples were characterised using Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (HD or bis(2-chloroethyl)sulphide) and soman (GD or (3,3'-dimethylbutan-2-yl)-methylphosphonofluoridate). Mn{sup 4+} content affects the decontamination activity; with increasing Mn{supmore » 4+} content the activity increases for sulphur mustard and decreases for soman. The best decontamination activities for sulphur mustard and soman were observed for samples TiMn{sub 3}7 with 18.6 wt.% Mn and TiMn{sub 5} with 2.1 wt.% Mn, respectively.« less

TiO{sub 2}/Bi{sub 2}(BDC){sub 3}/BiOCl nanoparticles decorated ultrathin nanosheets with excellent photocatalytic reaction activity and selectivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Shu-Mei; Ma, De-Kun, E-mail: dkma@wzu.edu.cn; Cai, Ping

2014-12-15

Graphical abstract: TiO{sub 2}/Bi{sub 2}(BDC){sub 3}/BiOCl nanoparticles decorated ultrathin nanosheets showed excellent photocatalytic reaction activity and selectivity. - Highlights: • TiO{sub 2}/Bi{sub 2}(BDC){sub 3}/BiOCl nanoparticles decorated ultrathin nanosheets were synthesized through a facile hydrothermal process. • The products showed excellent photocatalytic activities for the degradation of various dyes. • The photocatalytic activities of the composite materials could be easily adjusted through tuning the content of TiO{sub 2}. • TiO{sub 2}/Bi{sub 2}(BDC){sub 3}/BiOCl displayed obvious photocatalytic selectivity in mixed dyes systems of rhodamine B and eosin Y. - Abstract: Photocatalysts with excellent photocatalytic reaction activity and ideal selectivity are highly desirablemore » for pollutants clearance and purification of targeted organics from a mixture. Continued efforts toward the goal, we here present a facile hydrothermal route to synthesize TiO{sub 2}/Bi-benzenedicarboxylate/BiOCl nanoparticles decorated ultrathin nanosheets with a thickness less than 5 nm on a large scale. The as-synthesized products showed excellent photocatalytic activities for the degradation of various dyes such as rhodamine B, eosin Y and methylene blue in aqueous solution under visible light irradiation. The photocatalytic activities of TiO{sub 2}/Bi-benzenedicarboxylate/BiOCl nanocomposites for the degradation of rhodamine B and eosin Y could be adjusted through tuning the content of TiO{sub 2}. With increasing the amount of TiO{sub 2}, the composites showed declining photocatalytic activities in decomposing of rhodamine B while on the contrary they displayed enhanced photocatalytic activities in decomposing of eosin Y. Interestingly, TiO{sub 2}/Bi-benzenedicarboxylate/BiOCl composite nanosheets showed obvious photocatalytic selectivity in a mixed dyes system. The photocatalytic reaction and selectivity mechanisms of the nanocomposites for the degradation of the dyes were discussed on the basis of experimental results. The current study not only develops a new methodology to synthesize ultrathin nanosheets but also provides a novel strategy to design composite photocatalysts with high reaction activity and good selectivity.« less

Effects of the exposure of TiO2 nanoparticles on basil (Ocimum basilicum) for two generations.

PubMed

Tan, Wenjuan; Du, Wenchao; Darrouzet-Nardi, Anthony J; Hernandez-Viezcas, Jose A; Ye, Yuqing; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

2018-09-15

There is a lack of information about the transgenerational effects of titanium dioxide nanoparticles (nano-TiO 2 ) in plants. This study aimed to evaluate the impacts of successive exposure of nano-TiO 2 with different surface properties to basil (Ocimum basilicum). Seeds from plants exposed or re-exposed to pristine, hydrophobic, or hydrophilic nano-TiO 2 were cultivated for 65 days in soil unamended or amended with 750 mg·kg -1 of the respective particles. Plant growth, concentration of titanium and essential elements, as well as content of carbohydrates and chlorophyll were evaluated. There were no differences on Ti concentration in roots of plants sequentially exposed to pristine or hydrophobic nano-TiO 2 , or in roots of plants exposed to the corresponding particle, only in the second cycle. However, sequential exposure to hydrophilic particles resulted in 65.2% less Ti in roots, compared to roots of plants exposed the same particles, only in the second cycle. The Ti concentrations in shoots were similar in all treatments. On the other hand, pristine and hydrophilic particles reduced Mg in root by 115% and 81%, respectively, while pristine and hydrophobic particles reduced Ni in shoot by 84% and 75%, respectively, compared to unexposed plants in both cycles. Sequential exposure to pristine nano-TiO 2 increased stomatal conductance (214%, p ≤ 0.10), compared to plants that were never exposed. Hydrophobic and hydrophilic nano-TiO 2 reduced chlorophyll b (52%) and total chlorophyll (30%) but increased total sugar (186%) and reducing sugar (145%), compared to unexposed plants in both cycles. Sequential exposure to hydrophobic or hydrophilic nano-TiO 2 resulted in more adverse effects on photosynthesis but in positive effects on plant growth, compared to pristine nano-TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plucknett, K.P.; Becher, P.F.; Waters, S.B.

TiC/Ni{sub 3}Al composites were prepared using a simple melt-infiltration process, performed at either 1300 or 1400 C, with the Ni{sub 3}Al content varied over the range of 8--25 vol%. Densities >96% of theoretical were obtained for all composites. Four-point flexure strengths at 22 C increased as the Ni{sub 3}Al content increased (i.e., {approximately}1,100 MPa at 20 vol% Ni{sub 3}Al), with the highest strengths being observed for composites processed at 1300 C, because of reduced TiC grain size. Strengths at elevated temperatures increased with test temperature, up to {approximately}1,000 C. As with the yielding behavior of the Ni{sub 3}Al alloy used,more » a maximum in composite strength ({approximately}1,350 MPa) versus temperature was observed; this occurred at 950 C, which is {approximately}300 C above the yield maximum for the alloy. Extensive plastic strain was achieved in the composites even at high loading rates at 1,135 C, and the yield stress was dependent on the applied loading rate.« less

Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO2 Nanorod Arrays as Electron Transfer Layer.

PubMed

Zhang, Zhen-Long; Li, Jun-Feng; Wang, Xiao-Li; Qin, Jian-Qiang; Shi, Wen-Jia; Liu, Yue-Feng; Gao, Hui-Ping; Mao, Yan-Li

2017-12-01

In this paper, N-doped TiO 2 (N-TiO 2 ) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO 2 with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO 2 . To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO 2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO 2 than un-doped TiO 2 . The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO 2 than to un-doped TiO 2 . Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO 2 than that on un-doped TiO 2 .

Enhanced the hydrophobic surface and the photo-activity of TiO2-SiO2 composites

NASA Astrophysics Data System (ADS)

Wahyuni, S.; Prasetya, A. T.

2017-02-01

The aim of this research is to develop nanomaterials for coating applications. This research studied the effect of various TiO2-SiO2 composites in acrylic paint to enhance the hydrophobic properties of the substrate. Titanium dioxide containing silica in the range 20-35 mol% has been synthesized using sol-gel route. The XRD’s spectra show that increasing SiO2 content in the composite, decreasing its crystalline properties but increasing the surface area. TiO2-SiO2 composite was dispersed in acrylic paint in 2% composition by weight. The largest contact angle was 70, which produced by the substrate coated with TS-35-modified acrylic paint. This study also investigated the enhanced photo-activity of TiO2-SiO2 modified with poly-aniline. The XRD spectra show that the treatment does not change the crystal structure of TiO2. The photo-activity of the composite was evaluated by degradation of Rhodamine-B with visible light. The best performance of the degradation process was handled by the composite treated with 0.1mL anilines per gram of TiO2-SiO2 composite (TSP-A). On the other side, the contact angle 70 has not shown an excellent hydrophobic activity. However, the AFM spectra showed that nanoroughness has started to form on the surface of acrylic paint modified with TiO2-SiO2 than acrylic alone.

Distribution and stratigraphy of basaltic units in Maria Tranquillitatis and Fecunditatis: A Clementine perspective

NASA Technical Reports Server (NTRS)

Rajmon, D.; Spudis, P.

2004-01-01

Maria Tranquillitatis and Fecunditatis have been mapped based on Clementine image mosaics and derived iron and titanium maps. Impact craters served as stratigraphic probes enabling better delineation of compositionally different basaltic units, determining the distribution of subsurface basalts, and providing estimates of total basalt thickness and the thickness of the surface units. Collected data indicate that volcanism in these maria started with the eruption of low-Ti basalts and evolved toward medium- and high-Ti basalts. Some of the high-Ti basalts in Mare Tranquillitatis began erupting early and were contemporaneous with the low- and medium-Ti basalts; these units form the oldest units exposed on the mare surface. Mare Tranquillitatis is mostly covered with high- Ti basalts. In Mare Fecunditatis, the volume of erupting basalts clearly decreased as the Ti content increased, and the high-Ti basalts occur as a few patches on the mare surface. The basalt in both maria is on the order of several hundred meters thick and locally may be as thick as 1600 m. The new basalt thickness estimates generally fall within the range set by earlier studies, although locally differ. The medium- to high-Ti basalts exposed at the surfaces of both maria are meters to tens of meters thick.

Ferroelectric performances and crystal structures of (Pb, La)(Zr, Ti, Nb)O{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitamura, Naoto; Division of Ecosystem Research, Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510; Mizoguchi, Takuma

2014-02-15

In this study, we focused on Nb and La substituted Pb(Zr, Ti)O{sub 3}: i.e., (Pb, La)(Zr, Ti, Nb)O{sub 3}. As for the samples, dependences of ferroelectric properties on La and Nb compositions were examined. In addition, the crystal structures were analyzed by the Rietveld method, and then a relationship between the metal compositions and the crystal structures were discussed. From P–E hysteresis loop measurements, it was found that the remanant polarization of Pb(Zr, Ti)O{sub 3} was increased by both the La and Nb substitutions although the heavy substitution of La had an undesirable effect. It was also indicated that themore » Curie temperature decreased with increasing La content. The Rietveld analysis using synchrotron X-ray diffraction patterns demonstrated that the structure distortion was relaxed by the La and Nb substitutions. Such a change in the crystals was well consistent with the harmful effects on the Curie temperature and the remanent polarization by the heavy La substitution. - Graphical abstract: Rietveld refinement pattern of 2 mol% PbSiO{sub 3}-added Pb{sub 0.95}La{sub 0.05}Zr{sub 0.50}Ti{sub 0.45}Nb{sub 0.05}O{sub 3} (synchrotron X-ray diffraction). Display Omitted - Highlights: • (Pb,La)(Zr,Ti,Nb)O{sub 3} were successfully synthesized. • Remanant polarization of Pb(Zr,Ti)O{sub 3} was improved by substitutions of La and Nb. • Crystal structures of (Pb,La)(Zr,Ti,Nb)O{sub 3} were refined and the distortions were estimated.« less

Photocatalytic degradation of diclofenac using TiO2-SnO2 mixed oxide catalysts.

PubMed

Mugunthan, E; Saidutta, M B; Jagadeeshbabu, P E

2017-12-26

The complex nature of diclofenac limits its biological degradation, posing a serious threat to aquatic organisms. Our present work aims to eliminate diclofenac from wastewater through photocatalytic degradation using TiO 2 -SnO 2 mixed-oxide catalysts under various operating conditions such as catalyst loading, initial diclofenac concentration and initial pH. Different molar ratios of Ti-Sn (1:1, 5:1, 10:1, 20:1 and 30:1) were prepared by the hydrothermal method and were characterized. The results indicated that addition of Sn in small quantity enhances the catalytic activity of TiO 2 . Energy Band gap of the TiO 2 -SnO 2 catalysts was found to increase with an increase in Tin content. TiO 2 -SnO 2 catalyst with a molar ratio of 20:1 was found to be the most effective when compared to other catalysts. The results suggested that initial drug concentration of 20 mg/L, catalyst loading of 0.8 g/L and pH 5 were the optimum operating conditions for complete degradation of diclofenac. Also, the TiO 2 -SnO 2 catalyst was effective in complete mineralization of diclofenac with a maximum total organic carbon removal of 90% achieved under ultraviolet irradiation. The repeatability and stability results showed that the TiO 2 -SnO 2 catalyst exhibited an excellent repeatability and better stability over the repeated reaction cycles. The photocatalytic degradation of diclofenac resulted in several photoproducts, which were identified through LC-MS.

Effect of gamma irradiation on lipoxygenases, trypsin inhibitor, raffinose family oligosaccharides and nutritional factors of different seed coat colored soybean (Glycine max L.)

NASA Astrophysics Data System (ADS)

Kumar Dixit, Amit; Kumar, Vineet; Rani, Anita; Manjaya, J. G.; Bhatnagar, Deepak

2011-04-01

Three soybean genotypes Kalitur, Hara soya and NRC37 with black, green and yellow seed coat color, respectively, were gamma irradiated at 0.5, 2.0 and 5.0 kGy and tested for antinutritional and nutritional factors. Gamma irradiation at all doses reduced the level of lipoxygenase isomers, trypsin inhibitor (TI) and ascorbic acid in all the 3 soybean genotypes as compared to the unirradiated control. However, irradiation dose of 5.0 kGy increased the sucrose content of the soybean genotypes. No significant change was observed in oil, protein fatty acids and total tocopherol content of the 3 genotypes at any irradiation dose. It is suggested that inhibition of lipoxygenase, reduction in TI and ascorbic acid may be due to the breakage or oxidation of protein structure by the gamma irradiation. Similarly, gamma irradiation at higher doses may break glycosidic linkages in oligosaccharides to produce more sucrose and decrease the content of flatulence causing oligosaccharides.

Influences of superalloy composition and Pt content on the oxidation behavior of gamma–gamma prime NiPtAl bond coatings

DOE PAGES

Haynes, James A.; Unocic, Kinga A.; Lance, Michael J.; ...

2016-09-13

Here, the effects of superalloy composition and Pt content on the high-temperature oxidation behavior of γ–γ’ NiPtAl diffusion coatings were investigated over the temperature range of 1050–1150 °C. Simple NiPtAl diffusion coatings with 7 or 12 µm electroplated Pt thickness were evaluated in 1-h cycles in dry O 2 for up to 2500 cycles on four superalloys: directionally solidified (DS) alloy 142, 1st generation single-crystal (SX) alloy 1483, and 2nd generation SX alloys X4 and N5. Coatings on high-Hf alloy 142 experienced severe internal oxidation of Hf at all temperatures. Coatings on ~5 at.% Ti alloy 1483 were protective atmore » 1050 °C, but exhibited severe scale spallation at 1100 °C, with extensive formation of Ti- and Ni-rich oxides at the gas interface. Coatings with 7-µm Pt on X 4 were extremely protective at 1100 °C, but failed rapidly at 1150 °C, which also was associated with the formation of Ti-rich oxides. Increasing the coating Pt content on X 4 improved the 1150 °C oxidation behavior. Coatings on Ti-free N 5 showed the best performance at 1150 °C, especially with 12-µm Pt. Although γ–γ’ coatings can exhibit outstanding cyclic oxidation resistance with minimal Al depletion, they appear to be sensitive to substrate composition, as well as eventual Pt depletion due to interdiffusion.« less

[Experimental study and correction of the absorption and enhancement effect between Ti, V and Fe].

PubMed

Tuo, Xian-Guo; Mu, Ke-Liang; Li, Zhe; Wang, Hong-Hui; Luo, Hui; Yang, Jian-Bo

2009-11-01

The absorption and enhancement effects in X-ray fluorescence analysis for Ti, V and Fe elements were studied in the present paper. Three bogus duality systems of Ti-V/Ti-Fe/V-Fe samples were confected and measured by X-ray fluorescence analysis technique using HPGe semiconductor detector, and the relation curve between unitary coefficient (R(K)) of element count rate and element content (W(K)) were obtained after the experiment. Having analyzed the degree of absorption and enhancement effect between every two elements, the authors get the result, and that is the absorption and enhancement effect between Ti and V is relatively distinctness, while it's not so distinctness in Ti-Fe and V-Fe. After that, a mathematics correction method of exponential fitting was used to fit the R(K)-W(K) curve and get a function equation of X-ray fluorescence count rate and content. Three groups of Ti-V duality samples were used to test the fitting method and the relative errors of Ti and V were less than 0.2% as compared to the actual results.

Influence of CoO Nanoparticles on Properties of Barium Zirconium Titanate Ceramics

NASA Astrophysics Data System (ADS)

Jarupoom, Parkpoom; Jaita, Pharatree; Boothrawong, Narongdetch; Phatungthane, Thanatep; Sanjoom, Ratabongkot; Rujijanagul, Gobwute; Cann, David P.

2017-07-01

Composites of Ba(Zr0.07Ti0.93)O3 ceramic and CoO nanoparticles (at 1.0 vol.% to 3.0 vol.%) have been fabricated to investigate the effects of the CoO nanoparticles on the properties of the composites. X-ray diffraction data revealed that the modified samples contained Ba(Zr0.07Ti0.93)O3 and CoO phases. Addition of CoO nanoparticles improved the magnetic behavior and resulted in slight changes in ferroelectric properties. The composites showed a magnetoelectric effect in which the negative value of the magnetocapacitance increased with increasing CoO concentration. Examination of the dielectric spectra showed that the two phase-transition temperatures as observed for unmodified Ba(Zr0.07Ti0.93)O3 merged into a single phase-transition temperature for the composite samples. The composite samples also showed broad relative permittivity versus temperature ( ɛ r - T) curves with frequency dispersion. This dielectric behavior can be explained in terms of the Maxwell-Wagner mechanism. In addition, the Vickers hardness ( H v) value of the samples increased with increasing CoO content.

Interactions of ciprofloxacin (CIP), titanium dioxide (TiO2) nanoparticles and natural organic matter (NOM) in aqueous suspensions.

PubMed

Fries, Elke; Crouzet, Catherine; Michel, Caroline; Togola, Anne

2016-09-01

The aim of the present study was to investigate interactions of the antibiotic ciprofloxacin (CIP), titanium dioxide nanoparticles (TiO2 NP) and natural organic matter (NOM) in aqueous suspensions. The mean hydrodynamic diameter of particles of TiO2 NP and NOM in the suspensions ranged from 113 to 255nm. During batch experiments the radioactivity resulting from (14)CIP was determined in the filtrate (filter pore size 100nm) by scintillation measurements. Up to 72h, no significant sorption of NOM to TiO2 NP was observed at a TiO2 NP concentration of 5mg/L. When the concentration of TiO2 NP was increased to 500mg/L, a small amount of NOM of 9.5%±0.6% was sorbed at 72h. The low sorption affinity of NOM on TiO2 NP surfaces could be explained by the negative charge of both components in alkaline media or by the low hydrophobicity of the NOM contents. At a TiO2 NP concentration of 5mgL(-1), the sorption of CIP on TiO2 NP was insignificant (TiO2 NP/CIP ratio: 10). When the TiO2 NP/CIP ratio was increased to 1000, a significant amount of 53.6%±7.2% of CIP was sorbed on TiO2 NP under equilibrium conditions at 64h. In alkaline media, CIP is present mainly as zwitterions which have an affinity to sorb on negatively charged TiO2 NP surfaces. The sorption of CIP on TiO2 NP in the range of TiO2 NP concentrations currently estimated for municipal wastewater treatment plants is estimated to be rather low. The Freundlich sorption coefficients (KF) in the presence of NOM of 2167L(n)mgmg(-n)kg(-1) was about 10 times lower than in the absence of NOM. This is an indication that the particle fraction of NOM<100nm could play a role as a carrier for ionic organic micro-pollutants as CIP. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of composition modification on Ca{sub 0.5−x}Mg{sub x}Ti{sub 2}(PO{sub 4}){sub 3} (0.0 ≤ x ≤ 0.5) nanoparticles as electrodes for lithium batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vidal-Abarca, C., E-mail: q02vigac@uco.es; Aragón, M.J.; Lavela, P.

2014-01-01

Graphical abstract: - Highlights: • Cation mixing was determined in the Ca{sub 0.5−x}Mg{sub x}Ti{sub 2}(PO{sub 4}){sub 3} biphasic series. • Nanometric Ca{sub 0.15}Mg{sub 0.35}Ti{sub 2}(PO{sub 4}){sub 3} delivered 138 mAh/g at C/20 in lithium cells. • Low content of Ca{sup 2+} increases cell volume favoring Li{sup +} insertion in R-3c framework. • Diminution of R{sub SEI} and R{sub CT} for Ca{sub 0.15}Mg{sub 0.35}Ti{sub 2}(PO{sub 4}){sub 3} discharged electrodes. • Fast electrode response for x = 0.35. - Abstract: The Ca{sub 0.5−x}Mg{sub x}Ti{sub 2}(PO{sub 4}){sub 3} series (0.0 ≤ x ≤ 0.5) was prepared by a sol–gel method. X-ray diffraction patternsmore » showed two rhombohedral phases which coexist for intermediate compositions. Despite of the absence of a solid solution mechanism for the whole stoichiometry range, an appreciable cation mixing was observed in both phases. {sup 31}P MAS NMR spectroscopy revealed that low magnesium contents are incorporated to the calcium compound inducing changes in the ordering of the alkaline earth cations in M{sub 1} sites. Derivative plots of the voltage–capacity curves revealed two reversible regions ascribed to the reduction of Ti{sup 4+} to Ti{sup 3+}, ascribable to the subsequent insertion of lithium ions into M{sub 1} and M{sub 2} vacant sites. Capacity values as high as 138 mAh/g after the first discharge were monitored for nanometric Ca{sub 0.15}Mg{sub 0.35}Ti{sub 2}(PO{sub 4}){sub 3} at C/20. Cell cycling under successive kinetic rates revealed a good capacity retention for samples with x = 0.15 and 0.25. Impedance spectra were recorded in lithium cells discharged after different number of cycles at different C rates. The increase in charge transfer resistance was shown to be an important factor determining the electrode behavior on extended cycling.« less

Influences of urea–glycerol mixtures as mixed mesopore-controlling agents on tailoring physicochemical properties and photocatalytic H{sub 2} production activity of sol–gel-derived mesoporous-assembled TiO{sub 2} nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sreethawong, Thammanoon, E-mail: sreethawongt@imre.a-star.edu.sg; Ngamsinlapasathian, Supachai, E-mail: wonone@hotmail.com; Yoshikawa, Susumu

2013-01-15

Graphical abstract: Display Omitted Highlights: ► Mesoporous-assembled TiO{sub 2} nanocrystals were synthesized by modified sol–gel process. ► Urea–glycerol mixtures were applied as mixed mesopore-controlling agents. ► Urea and glycerol contents affected physicochemical properties of synthesized TiO{sub 2}. ► Photocatalytic H{sub 2} production activity also depended on urea and glycerol contents. ► 75 mol% urea and 25 mol% glycerol yielded the most photocatalytically active TiO{sub 2}. -- Abstract: In this work, the mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts were successfully synthesized by a sol–gel process with the aid of urea–glycerol mixtures used as mixed mesopore-controlling agents. The photocatalytic activity of the synthesizedmore » mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts was investigated for hydrogen production from the water splitting reaction using methanol as a hole scavenger under UV light irradiation. The synthesized TiO{sub 2} nanocrystal photocatalysts were systematically characterized by TG–DTA, N{sub 2} adsorption–desorption, SEM, high resolution TEM, and XRD analyses. The characterization results showed that the well-controlled contents of urea and glycerol in a urea–glycerol mixture at 75 mol% urea and 25 mol% glycerol resulted in not only the most highly porous network (i.e. the highest specific surface area and total pore volume, and the smallest mean mesopore diameter), but also the smallest crystallite size of the synthesized TiO{sub 2} nanocrystal photocatalyst. The photocatalytic reaction results, hence, revealed a much superior photocatalytic hydrogen production activity of the mesoporous-assembled TiO{sub 2} nanocrystal synthesized with 75 mol% urea and 25 mol% glycerol to the other synthesized TiO{sub 2} nanocrystals, also being much higher than those of the commercially available P-25 TiO{sub 2} and ST-01 TiO{sub 2} powders.« less

Adaptive strain prompting a pseudo-morphotropic phase boundary in ferroelectric (1-x ) Na0.5Bi0.5TiO3-x BaTiO3

NASA Astrophysics Data System (ADS)

Datta, K.; Neder, R. B.; Richter, A.; Göbbels, M.; Neuefeind, J. C.; Mihailova, B.

2018-05-01

The understanding of the atomistic origin of the morphotropic phase boundary (MPB) occurring in composition-temperature phase diagrams of ferroelectric solid solutions is a key topic in material science because materials often exhibit anomalous properties at the MPB. Here we reveal mesoscopic-scale structural correlations for a leading Pb-free ferroelectric system, (1 -x ) Na0.5Bi0.5TiO3-x BaTiO3 (NBT-x BT ), by examining atomic pair distribution functions and Raman scattering data at ambient conditions. We demonstrate that the amplification of the piezoelectric properties of NBT-x BT at the MPB are predominantly driven by an easy switchability resulting from a progressive decoupling between strain and polarization as the Ba content increases from zero to the critical MPB composition. It was observed that as Ba content increases towards MPB, competing local correlations, such as A-site chemical order, antiferrodistortive correlations of correlated BO6 tilts, and antipolar Bi shifts, are reduced, which in turn renders favorable conditions for easy switching of local dipoles under external fields. In addition, the evolving characteristics of the atomic dynamics as a function of composition suggest that the local potential functions of the cations are not completely flat at the MPB. Altogether, our results reveal atomistic mechanisms responsible for the observed elevated MPB properties in the case of NBT-x BT which imply that the so-called MPB of NBT-x BT should not be categorized as originally introduced for Pb-containing solid solutions.

Migration laws of major elements of Laowashan bauxite in Zunyi area, northern Guizhou province of China

NASA Astrophysics Data System (ADS)

Cui, Tao

2018-01-01

After exploring migration laws of major elements in Laowashan bauxite of northern Guizhou Province by geochemical methods, it was found that: 1) Si was negatively correlated to Al and Ti; Al showed significant negative correlations with Si and Fe; Al was positively correlated to Ti. 2) The content of Si and Fe was low in the middle part, high at the top and the highest at the bottom. The content of Al and Ti is the highest in the middle, followed by the content at the top and the bottom successively. 3) Karst depressions are favorable for groundwater discharge through leaching, leading to heavy loss of Fe in ZK-CS1.

The Effect of Titanium Dioxide (TiO2) Nanoparticles on Hydroxyapatite (HA)/TiO2 Composite Coating Fabricated by Electrophoretic Deposition (EPD)

NASA Astrophysics Data System (ADS)

Amirnejad, M.; Afshar, A.; Salehi, S.

2018-05-01

Composite coatings of Hydroxyapatite (HA) with ceramics, polymers and metals are used to modify the surface structure of implants. In this research, HA/TiO2 composite coating was fabricated by electrophoretic deposition (EPD) on 316 stainless steel substrate. HA/TiO2 composite coatings with 5, 10 and 20 wt.% of TiO2, deposited at 40 V and 90 s as an optimum condition. The samples coated at this condition led to an adherent, continuous and crack-free coating. The influence of TiO2 content was studied by performing different characterization methods such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), corrosion resistance in simulated body fluid (SBF), coating's dissolution rate in physiological solution and bond strength to the substrate. The results showed that the higher amount of TiO2 in the composite coating led to increase in bond strength of coating to stainless steel substrate from 3 MPa for HA coating to 5.5 MPa for HA-20 wt.% TiO2 composite coating. In addition, it caused to reduction of corrosion current density of samples in the SBF solution from 18.92 μA/cm2 for HA coating to 6.35 μA/cm2 for HA-20 wt.% TiO2 composite coating.

The Effect of Titanium Dioxide (TiO2) Nanoparticles on Hydroxyapatite (HA)/TiO2 Composite Coating Fabricated by Electrophoretic Deposition (EPD)

NASA Astrophysics Data System (ADS)

Amirnejad, M.; Afshar, A.; Salehi, S.

2018-04-01

Composite coatings of Hydroxyapatite (HA) with ceramics, polymers and metals are used to modify the surface structure of implants. In this research, HA/TiO2 composite coating was fabricated by electrophoretic deposition (EPD) on 316 stainless steel substrate. HA/TiO2 composite coatings with 5, 10 and 20 wt.% of TiO2, deposited at 40 V and 90 s as an optimum condition. The samples coated at this condition led to an adherent, continuous and crack-free coating. The influence of TiO2 content was studied by performing different characterization methods such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), corrosion resistance in simulated body fluid (SBF), coating's dissolution rate in physiological solution and bond strength to the substrate. The results showed that the higher amount of TiO2 in the composite coating led to increase in bond strength of coating to stainless steel substrate from 3 MPa for HA coating to 5.5 MPa for HA-20 wt.% TiO2 composite coating. In addition, it caused to reduction of corrosion current density of samples in the SBF solution from 18.92 μA/cm2 for HA coating to 6.35 μA/cm2 for HA-20 wt.% TiO2 composite coating.

Controlled Synthesis of CuS/TiO2 Heterostructured Nanocomposites for Enhanced Photocatalytic Hydrogen Generation through Water Splitting.

PubMed

Chandra, Moumita; Bhunia, Kousik; Pradhan, Debabrata

2018-04-16

Photocatalytic hydrogen (H 2 ) generation through water splitting has attracted substantial attention as a clean and renewable energy generation process that has enormous potential in converting solar-to-chemical energy using suitable photocatalysts. The major bottleneck in the development of semiconductor-based photocatalysts lies in poor light absorption and fast recombination of photogenerated electron-hole pairs. Herein we report the synthesis of CuS/TiO 2 heterostructured nanocomposites with varied TiO 2 contents via simple hydrothermal and solution-based process. The morphology, crystal structure, composition, and optical properties of the as-synthesized CuS/TiO 2 hybrids are evaluated in detail. Controlling the CuS/TiO 2 ratio to an optimum value leads to the highest photocatalytic H 2 production rate of 1262 μmol h -1 g -1 , which is 9.7 and 9.3 times higher than that of pristine TiO 2 nanospindles and CuS nanoflakes under irradiation, respectively. The enhancement in the H 2 evolution rate is attributed to increased light absorption and efficient charge separation with an optimum CuS coverage on TiO 2 . The photoluminescence and photoelectrochemical measurements further confirm the efficient separation of charge carriers in the CuS/TiO 2 hybrid. The mechanism and synergistic role of CuS and TiO 2 semiconductors for enhanced photoactivity is further delineated.

Durability Assessment of TiAl Alloys

NASA Technical Reports Server (NTRS)

Draper, Susan L.; Lerch, Bradley A.

2008-01-01

The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

Measurement of Ti[superscript +3] / Ti[superscript +4] ratios in pyroxene in Wark-Loveing rims: Evidence for formation in a reducing solar nebula

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simon, S.B.; Sutton, S.R.; Grossman, L.

2006-12-13

Ti-bearing clinopyroxene, known as fassaite, is a major phase in the interiors of coarse-grained, Ca-, Al-rich refractory inclusions (CAIs). Electron microprobe (EMP) analyses of such pyroxene yield low cation sums when normalized to six oxygen anions if it is assumed that all Ti is present as Ti{sup 4+}. Instead, we can assume that there is one Ca cation [1] and two tetrahedral cations present per six oxygens, and can then calculate a Ti{sup 3+}/(Ti{sup 3+} + Ti{sup 4+}), or Ti{sup 3+}/Ti{sup tot}, ratio that gives exactly one cation in the remaining site and a total of exactly four cations permore » six oxygens. Additional evidence for the presence of Ti in multiple valence states includes: pleochroism in Ti-rich crystals with negligible amounts of other multivalent elements; results from measurements of optical spectra [2]; and X-ray absorption near-edge structure (XANES) analysis [3]. Calculation of accurate Ti{sup 3+}/Ti{sup tot} ratios from EMP analyses is generally limited to analyses with >4 wt% TiO{sub 2}{sup tot} (all Ti as TiO{sub 2}), because at low Ti contents the analytical uncertainties approach the magnitude of the cation deficit caused by assuming all Ti is Ti{sup 4+}. Many refractory inclusions are enclosed in sequences of mineralogically distinct layers, first described by [4], that must have formed after the host inclusions did. In most cases, from the CAI outward, the sequence consists of a layer of spinel {+-} perovskite; voids, melilite, or alteration products; clinopyroxene; and hedenbergite. The pyroxene layer may be immediately adjacent to spinel and is commonly zoned from Ti-rich fassaite nearest the spinel layer to Ti-poor aluminous diopside over distances of {approx}10 {micro}m [4]. A recent study of the pyroxene in the rims of one Allende and two Leoville inclusions [5] found that most points analyzed by electron probe had between 4 and 7 wt% TiO{sub 2}{sup tot} and 0.7-1.7 wt% FeO. Those authors also found < 1 Ca cation, but very close to 4 total cations, per 6 oxygen ions, and therefore little or no Ti{sup 3+}. They kindly loaned us one of their samples for analysis, and we also found low Ca contents, high FeO contents ({approx}1 wt%) and undetectable to low Ti{sup 3+} contents compared to fassaite found in the interiors of CAIs. The low-Ca analyses would seem to reflect the presence of an enstatite component in addition to the standard fassaite components [1], but despite inclusion of such a component in our calculations we have not been able to satisfactorily resolve the analyses into pyroxene endmembers. This is a hint that pyroxene analysis spots are contaminated with another phase, a serious problem for stoichiometrydependent calculation of Ti{sup 3+}/Ti{sup tot} ratios. We need to know whether or not rim pyroxene contains Ti{sup 3+} because of its importance as a recorder of nebular oxygen fugacity, but we are unsure of how to normalize EMP analyses in this case, so we cannot calculate Ti{sup 3+}/Ti{sup tot} accurately. We therefore decided to measure the Ti{sup 3+}/Ti{sup tot} of rim pyroxene directly, by XANES. We have conducted a detailed study of pyroxene in the rim on TS24, a fluffy Type A inclusion from Allende. This inclusion is large and very irregularly shaped, giving it a relatively high surface area. It has a well-developed rim sequence, from the CAI outward, of spinel, clinopyroxene zoned from Ti-, Al-rich to nearly pure diopside over {approx}20 {micro}m, and hedenbergite. The spinel-pyroxene and diopside-hedenbergite contacts are sharp.« less

New anatase-type Til-2xNbxAlxO2 solid solution nanoparticles: direct formation, phase stability, and photocatalytic performance.

PubMed

Hirano, Masanori; Ito, Takaharu

2006-12-01

New anatase-type titania solid solutions co-doped with niobium and aluminum (Til-2xNbxAIlxO2 (X = 0 -0.20)) were synthesized as nanoparticles from precursor solutions of TiOSO4, NbCl5, and Al(NO3)3 under mild hydrothermal conditions at 180 degrees C for 5 h using the hydrolysis of urea. The lattice parameters a0 and c0 of anatase slightly and gradually increased, when the content of niobium and aluminum increased from X = 0 to 0.20. The crystallite size of anatase increased from 12 to 28 nm with increasing the value of X from 0 to 0.20. Their photocatalytic activity and adsorptivity were evaluated separately by the measurement of the concentration of methylene blue (MB) remained in the solution in the dark or under UV-light irradiation. The adsorptivity of TiO2 was improved by the formation of anatase-type Til-2xNbxAlxO2 solid solutions. The photocatalytic activity of anatase-type Til-2xNbxAlxO2 solid solutions was superior to that of commercially available anatase-type pure TiO2 (ST-01) and anatase-type pure TiO2 hydrothermally prepared. The new anatase phase of Til-2xNbxAlxO2 (X = 0-0.20) solid solutions existed stably up to 850 0C during heat treatment in air. In comparison with hydrothermal pure TiO2, the starting temperature of anatase-to-rutile phase transformation was delayed by the formation of Ti1-2xNbxAlxO, (X = 0-0.20) solid solutions, although its completing temperature was accelerated.

Correlation between Mechanical Behavior and Actuator-type Performance of Ni-Ti-Pd High-temperature Shape Memory Alloys

NASA Technical Reports Server (NTRS)

Bigelow, Glen S.; Padula, Santo A., II; Garg, Anita; Noebe, Ronald D.

2007-01-01

High-temperature shape memory alloys in the NiTiPd system are being investigated as lower cost alternatives to NiTiPt alloys for use in compact solid-state actuators for the aerospace, automotive, and power generation industries. A range of ternary NiTiPd alloys containing 15 to 46 at.% Pd has been processed and actuator mimicking tests (thermal cycling under load) were used to measure transformation temperatures, work behavior, and dimensional stability. With increasing Pd content, the work output of the material decreased, while the amount of permanent strain resulting from each load-biased thermal cycle increased. Monotonic isothermal tension testing of the high-temperature austenite and low temperature martensite phases was used to partially explain these behaviors, where a mismatch in yield strength between the austenite and martensite phases was observed at high Pd levels. Moreover, to further understand the source of the permanent strain at lower Pd levels, strain recovery tests were conducted to determine the onset of plastic deformation in the martensite phase. Consequently, the work behavior and dimensional stability during thermal cycling under load of the various NiTiPd alloys is discussed in relation to the deformation behavior of the materials as revealed by the strain recovery and monotonic tension tests.

Correlation between mechanical behavior and actuator-type performance of Ni-Ti-Pd high-temperature shape memory alloys

NASA Astrophysics Data System (ADS)

Bigelow, Glen S.; Padula, Santo A., II; Garg, Anita; Noebe, Ronald D.

2007-04-01

High-temperature shape memory alloys in the NiTiPd system are being investigated as lower cost alternatives to NiTiPt alloys for use in compact solid-state actuators for the aerospace, automotive, and power generation industries. A range of ternary NiTiPd alloys containing 15 to 46 at.% Pd has been processed and actuator mimicking tests (thermal cycling under load) were used to measure transformation temperatures, work behavior, and dimensional stability. With increasing Pd content, the work output of the material decreased, while the amount of permanent strain resulting from each load-biased thermal cycle increased. Monotonic isothermal tension testing of the high-temperature austenite and low temperature martensite phases was used to partially explain these behaviors, where a mismatch in yield strength between the austenite and martensite phases was observed at high Pd levels. Moreover, to further understand the source of the permanent strain at lower Pd levels, strain recovery tests were conducted to determine the onset of plastic deformation in the martensite phase. Consequently, the work behavior and dimensional stability during thermal cycling under load of the various NiTiPd alloys is discussed in relation to the deformation behavior of the materials as revealed by the strain recovery and monotonic tension tests.

Removal of polycyclic aromatic hydrocarbons (PAHs) from industrial sludges in the ambient air conditions: automotive industry.

PubMed

Karaca, Gizem; Tasdemir, Yucel

2013-01-01

Removal of polycyclic aromatic hydrocarbons (PAHs) existed in automotive industry treatment sludge was examined by considering the effects of temperature, UV, titanium dioxide (TiO2) and diethyl amine (DEA) in different dosages (i.e., 5% and 20%) in this study. Application of TiO2 and DEA to the sludge samples in ambient environment was studied. Ten PAH (Σ10 PAH) compounds were targeted and their average value in the sludge was found to be 4480 ± 1450 ng/g dry matter (DM). Total PAH content of the sludge was reduced by 25% in the ambient air environment. Meteorological conditions, atmospheric deposition, evaporation and sunlight irradiation played an effective role in the variations in PAH levels during the tests carried out in ambient air environment. Moreover, it was observed that when the ring numbers of PAHs increased, their removal rates also increased. Total PAH level did not change with the addition of 5% DEA and only 10% decreased with 5% TiO2 addition. PAH removal ratios were 8% and 32% when DEA (20%) and TiO2 (20%) were added, respectively. It was concluded that DEA was a weak photo-sensitizer yet TiO2 was effective only at 20% dosage.

Titanium dioxide nanoparticles relieve silk gland damage and increase cocooning of Bombyx mori under phoxim-induced toxicity.

PubMed

Li, Bing; Yu, Xiaohong; Gui, Suxin; Xie, Yi; Hong, Jie; Zhao, Xiaoyang; Sheng, Lei; Sang, Xuezi; Sun, Qingqing; Wang, Ling; Shen, Weide; Hong, Fashui

2013-12-18

Organophosphate pesticides are applied widely in the world for agricultural purposes, and their exposures often resulted in non-cocooning of Bombyx mori in China. TiO2 nanoparticles have been demonstrated to increase pesticide resistance of Bombyx mori. While the toxicity of phoxim is well-documented, very limited information exists on the mechanisms of TiO2 nanoparticles improving the cocooning function of Bombyx mori following exposure to phoxim. The present study was, therefore, undertaken to determine whether TiO2 nanoparticles attenuate silk gland injury and elevate cocooning of B. mori following exposure to phoxim. The findings suggested that phoxim exposure resulted in severe damages of the silk gland structure and significantly decreased the cocooning in the silk gland of Bombyx mori. Furthermore, phoxim exposure significantly resulted in reductions of total protein concentrations and suppressed expressions of silk protein synthesis-related genes, including Fib-L, Fib-H, P25, Ser-2, and Ser-3, in the silk gland. TiO2 nanoparticle pretreatment, however, could significantly relieve silk gland injury of Bombyx mori. Importantly, TiO2 nanoparticles could remarkably elevate cocooning and total protein contents and promote expressions of Fib-L, Fib-H, P25, Ser-2, and Ser-3 in the silk gland following exposure to phoxim.

Enhancement of thermoelectric performance in strontium titanate by praseodymium substitution

NASA Astrophysics Data System (ADS)

Kovalevsky, A. V.; Yaremchenko, A. A.; Populoh, S.; Weidenkaff, A.; Frade, J. R.

2013-02-01

In order to identify the effects of Pr additions on thermoelectric properties of strontium titanate, crystal structure, electrical and thermal conductivity, and Seebeck coefficient of Sr1-xPrxTiO3 (x = 0.02-0.30) materials were studied at 400 < T < 1180 K under highly reducing atmosphere. The mechanism of electronic transport was found to be similar up to 10% of praseodymium content, where generation of the charge carriers upon substitution resulted in significant increase of the electrical conductivity, moderate decrease in Seebeck coefficient, and general improvement of the power factor. Formation of point defects in the course of substitution led to suppression of the lattice thermal conductivity, whilst the contribution from electronic component was increasing with carrier concentration. Possible formation of layered structures and growing distortion of the perovskite lattice resulted in relatively low thermoelectric performance for Sr0.80Pr0.20TiO3 and Sr0.70Pr0.30TiO3. The maximum dimensionless figure of merit was observed for Sr0.90Pr0.10TiO3 and amounted to ˜0.23 at 670 K and ˜0.34 at 1170 K, close to the values, obtained in similar conditions for the best bulk thermoelectrics, based on rare-earth substituted SrTiO3.

Shape memory behavior of single crystal and polycrystalline Ni-rich NiTiHf high temperature shape memory alloys

NASA Astrophysics Data System (ADS)

Saghaian, Sayed M.

NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing. Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti 29.3Hf20, Ni51.2Ti28.8Hf20, and Ni52Ti28Hf20 (at. %)) were systematically characterized in the furnace cooled condition. H-phase precipitates were formed during furnace cooling in compositions with greater than 50.3Ni and the driving force for nucleation increased with Ni content. Alloy strength increased while recoverable strain decreased with increasing Ni content due to changes in precipitate characteristics. The effects of the heat treatments on the transformation characteristics and microstructure of the Ni-rich NiTiHf shape memory alloys have been investigated. Transformation temperatures are found to be highly annealing temperature dependent. Generation of nanosize precipitates (˜20 nm in size) after three hours aging at 450 °C and 550 °C improved the strength of the material, resulting in a near perfect dimensional stability under high stress levels (> 1500 MPa) with a work output of 20-30 J cm- 3. Superelastic behavior with 4% recoverable strain was demonstrated at low and high temperatures where stress could reach to a maximum value of more than 2 GPa after three hours aging at 450 and 550 °C for alloys with Ni great than 50.3 at. %. Shape memory properties of polycrystalline Ni50.3Ti29.7 Hf20 alloys were studied via thermal cycling under stress and isothermal stress cycling experiments in tension. Recoverable strain of ˜5% was observed for the as-extruded samples while it was decreased to ˜4% after aging due to the formation of precipitates. The aged alloys demonstrated near perfect shape memory effect under high tensile stress level of 700 MPa and perfect superelasticity at high temperatures up to 230 °C. Finally, the tension-compression asymmetry observed in NiTiHf where recoverable tensile strain was higher than compressive strain. The shape memory properties of solutionized and aged Ni-rich Ni50.3Ti29.7Hf20 single crystals were investigated along the [001], [011], and [111] orientations in compression. [001]-oriented single crystals showed high dimensional stability under stress levels as high as 1500 MPa in both the solutionized and aged conditions, but with transformation strains of less than 2%. Perfect superelasticity with recoverable strain of more than 4% was observed for solutionized and 550 °C-3h aged single crystals along the [011] and [111] orientations, and general superelastic behavior was observed over a wide temperature range. The calculated transformation strains were higher than the experimentally observed strains since the calculated strains could not capture the formation of martensite plates with (001) compound twins. KEYWORDS: NiTiHf, High Temperature Shape memory alloys, Mechanical Characterization, High Strength Shape Memory Alloy, Orientation Dependence of NiTiHf Sayed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Songhak; Maegli, Alexandra E.; Karvonen, Lassi

Polycrystalline SrTiO{sub 3} and SrTi(O,F){sub 3} powders were synthesized by a solid-state reaction. A partial substitution of oxygen by nitrogen was subsequently carried out using thermal ammonolysis resulting in SrTi(N,O){sub 3} and SrTi(N,O,F){sub 3}. Powder X-ray diffraction (XRD) revealed a cubic perovskite structure with space group Pm-3m for all samples. The thermal ammonolysis slightly increased the lattice parameters, crystallite sizes and strain. As a result from the co-substitution of oxygen with nitrogen and fluorine for SrTi(N,O,F){sub 3}, highly distorted TiO{sub 6} octahedra were detected using X-ray absorption near edge structure (XANES) spectroscopy. The weakening of all active modes of themore » Raman spectra after thermal ammonolysis also indicated enhanced distortions in the local crystal structure. SrTi(N,O,F){sub 3} has the largest amount of nitrogen as well as fluorine among all four samples as determined by thermogravimetric analysis (TGA), elemental analysis and X-ray photoelectron spectroscopy (XPS). In the UV–vis spectra a distinctive shift of the absorption-edge energy was observed exclusively for the SrTi(N,O,F){sub 3} sample from 390 to 510 nm corresponding to a bandgap narrowing from 3.18 to 2.43 eV. - Graphical abstract: Figure shows the shift of the absorption-edge energy for the SrTi(N,O,F){sub 3} sample from 390 to 510 nm corresponding to a bandgap narrowing from 3.18 to 2.43 eV. Display Omitted - Highlights: • Synthesis of phase-pure SrTi(N,O,F){sub 3} via solid-state reaction. • The incorporated nitrogen contents increase by the presence of fluorine in SrTi(N,O,F){sub 3}. • Co-substitution with nitrogen and fluorine is beneficial for the bandgap narrowing compared to by only nitrogen or fluorine substitution.« less

Increasing Ti-6Al-4V brazed joint strength equal to the base metal by Ti and Zr amorphous filler alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganjeh, E., E-mail: navidganjehie@sina.kntu.ac.ir; Sarkhosh, H.; Bajgholi, M.E.

Microstructural features developed along with mechanical properties in furnace brazing of Ti-6Al-4V alloy using STEMET 1228 (Ti-26.8Zr-13Ni-13.9Cu, wt.%) and STEMET 1406 (Zr-9.7Ti-12.4Ni-11.2Cu, wt.%) amorphous filler alloys. Brazing temperatures employed were 900-950 Degree-Sign C for the titanium-based filler and 900-990 Degree-Sign C for the zirconium-based filler alloys, respectively. The brazing time durations were 600, 1200 and 1800 s. The brazed joints were evaluated by ultrasonic test, and their microstructures and phase constitutions analyzed by metallography, scanning electron microscopy and X-ray diffraction analysis. Since microstructural evolution across the furnace brazed joints primarily depends on their alloying elements such as Cu, Ni andmore » Zr along the joint. Accordingly, existence of Zr{sub 2}Cu, Ti{sub 2}Cu and (Ti,Zr){sub 2}Ni intermetallic compounds was identified in the brazed joints. The chemical composition of segregation region in the center of brazed joints was identical to virgin filler alloy content which greatly deteriorated the shear strength of the joints. Adequate brazing time (1800 s) and/or temperature (950 Degree-Sign C for Ti-based and 990 Degree-Sign C for Zr-based) resulted in an acicular Widmanstaetten microstructure throughout the entire joint section due to eutectoid reaction. This microstructure increased the shear strength of the brazed joints up to the Ti-6Al-4V tensile strength level. Consequently, Ti-6Al-4V can be furnace brazed by Ti and Zr base foils produced excellent joint strengths. - Highlights: Black-Right-Pointing-Pointer Temperature or time was the main factors of controlling braze joint strength. Black-Right-Pointing-Pointer Developing a Widmanstaetten microstructure generates equal strength to base metal. Black-Right-Pointing-Pointer Brittle intermetallic compounds like (Ti,Zr){sub 2}Ni/Cu deteriorate shear strength. Black-Right-Pointing-Pointer Ti and Zr base filler alloys were the best choice for brazing Ti-6Al-4V.« less

Phase composition and tribomechanical properties of Ti-B-C nanocomposite coatings prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Sánchez-López, J. C.; Abad, M. D.; Justo, A.; Gago, R.; Endrino, J. L.; García-Luis, A.; Brizuela, M.

2012-09-01

Protective nanocomposite coatings based on hard ceramic phases (TiC, TiB2) combined with amorphous carbon (a-C) are of interest because of their adequate balance between mechanical and tribological performances. In this work, Ti-B-C nanocomposite coatings were prepared by co-sputtering of graphite and TiB2 targets. Varying the discharge power ratio applied to the graphite and TiB2 targets from 0 to 2, the a-C content in the coatings could be tuned from 0 to 60%, as observed by means of Raman and x-ray photoelectron spectroscopy (XPS). The microstructural characterization demonstrated a progressive decrease in crystallinity from an initial nanocrystalline (nc) TiB2-like structure to a distorted TiBxCy ternary compound with increasing C concentration. X-ray absorption near-edge structure measurements on the B K-edge helped to determine a hexagonal arrangement around the B atoms in the ternary TiBxCy phase. A fitting analysis of the C 1s XPS peak allowed us to evaluate the relative amount of a-C and TiBxCy components. A drastic change in hardness (from 52 to 13 GPa) and friction coefficient values (from 0.8 to 0.2) is noticed when moving from nc-TiB2 to TiBC/a-C nanocomposites. The fraction of a-C necessary to decrease the friction below 0.2 was found to be 45%. Raman observation of the wear tracks determined the presence of disordered sp2-bonded carbon phase associated with the diminution of the friction level.

Water sensitivity of the seismic properties of upper-mantle olivine

NASA Astrophysics Data System (ADS)

Cline, Christopher; David, Emmanuel; Faul, Ulrich; Berry, Andrew; Jackson, Ian

2017-04-01

The wave speeds and attenuation of seismic waves in the upper mantle are expected to be strongly influenced by the defect chemistry of olivine grain interiors and the associated chemical complexity of grain-boundary regions. Changes in chemical environment (oxygen fugacity and/or water fugacity) can impose different defect chemistries, including the creation and retention of hydrous defects, and therefore can directly influence anelastic relaxation involving stress-induced migration of lattice defects and/or grain-boundary sliding. Here we report the first low-frequency experimental study of the seismic properties of olivine under water-undersaturated conditions. Three synthetic sol-gel derived olivine (Fo90) specimens were fabricated by hot-pressing in welded Pt capsules with various concentrations of hydroxyl, chemically bound as doubly protonated Si vacancies, charge balanced by substitution of Ti on a neighboring M-site (i.e., the Ti-clinohumite-like defect). Hydroxyl contents, determined following the subsequent mechanical testing within Pt sleeves, increased systematically with the amount of added Ti-dopant. Added Ti concentrations ranged between 176 and 802 atom ppm Ti/Si, resulting in concentrations of bound hydrogen in the three samples ranging between 330 and 1150 atom ppm H/Si. Each hot-pressed specimen was precision ground and then sleeved in Pt for mechanical testing in forced torsional oscillation under water-undersaturated conditions. Forced-oscillation tests were conducted at seismic periods of 1 - 1000 s and 200 MPa confining pressure during slow staged cooling from 1200 to 25°C. Each Ti-doped specimen showed mechanical behavior of the high-temperature background type involving monotonically increasing dissipation and decreasing shear modulus with increasing oscillation period and increasing temperature. Comparison of the mechanical data acquired in these water-undersaturated conditions with a similarly tested, but dry, Ti-bearing specimen (enclosed within an Ni-Fe sleeve under more reducing conditions) shows a marked contrast. The OH-bearing specimens exhibit much lower shear moduli (by as much as 80%) and higher levels of dissipation (by as much as 0.5 log units in Q-1), but also limited sensitivity of the seismic properties to the total water content among the hydrated specimens in the series. These results indicate that the higher oxygen and water fugacities prevailing within Pt-sleeved specimens result in lower shear moduli and higher dissipation under water-undersaturated conditions - presumably attributable to contrasting defect populations and/or grain boundary chemistries. Clarification of the relative roles of grain-boundary sliding and any additional intragranular relaxation under increased fH2O and fO2 thus offers the prospect of an improved understanding of the seismological signature of more oxidized/hydrous portions of the Earth's upper mantle, such as subduction zone environments.

Corrosion behavior of binary titanium aluminide intermetallics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saffarian, H.M.; Gan, Q.; Hadkar, R.

1996-08-01

The corrosion behavior of arc-melted binary titanium aluminide intermetallics TiAl, Ti{sub 2}Al, and TiAl{sub 3} in aqueous sodium sulfate and sodium chloride solutions was measured and compared to that of pure Ti and Al. Effects of electrolyte composition (e.g., sulfate [0.25 M SO{sub 4}{sup 2}{sup {minus}}], chloride [0.1 to 1.0 M Cl{sup {minus}}], and pH [3 to 10]) were examined. Anodic polarization of titanium aluminides in aqueous SO{sub 4}{sup 2}{sup {minus}} solutions was similar (showing passive behavior), but no pitting or pitting potential (E{sub pit}) was observed. In aqueous NaCl, however, titanium aluminides were susceptible to pitting, and E{sub pit}more » decreased with increasing Al content (i.e., Ti{sub 3}Al had the highest E{sub pit} and, therefore, a greater resistance to pitting, followed by TiAl and TiAl{sub 3}). For TiAl, E{sub pit} was slightly dependent upon pH or Cl{sup {minus}} concentration. Pit morphology and E{sub pit} values were quite different for TiAl compared to Ti{sub 3}Al. TiAl showed numerous small pits, whereas Ti{sub 3}Al exhibited fewer but larger and deeper pits. The larger pit density for TiAl was associated with Al-rich interdendrite regions. One interesting feature of the anodic polarization curves for Ti{sub 3}Al was a small anodic peak frequently observed at {approximately}1.4 V{sub SCE} to 1.8 V{sub SCE}. Results suggested this peak was associated with pit initiation, since pitting initiated concurrently with the peak or immediately afterward.« less

Photocatalytic degradation properties of V-doped TiO2 to automobile exhaust.

PubMed

Wang, Tong; Shen, Dongya; Xu, Tao; Jiang, Ruiling

2017-05-15

To improve the photocatalytic degradation properties of titanium dioxide (TiO 2 ) used as raw materials for purifying automobile exhaust (AE), the vanadium (V)-doped TiO 2 samples were prepared. The photocatalytic degradation efficiencies of V-doped TiO 2 to each component in AE were evaluated under ultraviolet (UV) and visible light irradiation, respectively. Results indicated that the photocatalytic activity of V-doped TiO 2 to AE was higher than that of pure TiO 2 , and the optimal V dopant content of TiO 2 was 1.0% under UV light irradiation. The degradation efficiencies of V-doped TiO 2 to NOx and HC were higher than those to CO 2 and CO in AE because of the reversible reaction between CO 2 and CO. In addition, it was found that the photocatalytic degradation efficiencies of V-doped TiO 2 to each component in AE were also increased under visible light irradiation. The V-doped TiO 2 also showed higher degradation efficiencies to NOx and HC than those to CO 2 and CO under visible light irradiation. The V doped TiO 2 presented higher photocatalytic activity to CO 2 than that to CO, but the reversible reaction between CO and CO 2 was not found under visible light irradiation. The photocatalytic reactions of pure and V-doped TiO 2 samples to each component in AE followed the first order kinetic pathway under the two light irradiations. It is concluded that the V doping is a feasible method to improve the photocatalytic degradation properties of TiO 2 to AE for air purification, developing a sustainable environmental purification technology based on TiO 2 materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Composition dependence of structural and optical properties in epitaxial Sr(Sn1-xTix)O3 films

NASA Astrophysics Data System (ADS)

Liu, Qinzhuang; Li, Bing; Li, Hong; Dai, Kai; Zhu, Guangping; Wang, Wei; Zhang, Yongxing; Gao, Guanyin; Dai, Jianming

2015-03-01

Epitaxial Sr(Sn1-xTix)O3 (SSTO, x = 0-1) thin films were grown on MgO substrates by a pulsed laser deposition technique. The effects of composition on the structural and optical properties of SSTO films were investigated. X-ray diffraction studies show that the lattice parameter decreases from 4.041 to 3.919 Å gradually with increasing Ti content from 0 to 1 in SSTO films. Optical spectra analysis reveals that the band gap energy Eg decreases continuously from 4.44 to 3.78 eV over the entire doping range, which is explained by the decreasing degree of octahedral tilting distortion and thus the increasing tolerance factor caused by the increasing small-Ti-ion doping concentration.

Curcumin-sensitized TiO2 for enhanced photodegradation of dyes under visible light

NASA Astrophysics Data System (ADS)

Buddee, Supat; Wongnawa, Sumpun; Sriprang, Pimpaporn; Sriwong, Chaval

2014-04-01

Curcumin was coated on P25 TiO2 by using impregnation method from freshly prepared curcumin solution. The resulting products (Cur-TiO2-P25) was studied by several techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transformed infrared spectroscopy, specific surface area by the Brunauer-Emmett-Teller method, and UV-Vis diffused reflectance spectroscopy. Experimental results revealed that impregnation of curcumin at 0.5, 3, 5, and 7 wt% did not affect the native phase of anatase and rutile in P25 significantly, however, it caused red shift of absorption onset in all curcumin-coated samples. The Cur-TiO2-P25 showed enhanced adsorption efficiency and increased photocatalytic activity under visible light with optimal result at 5 wt% curcumin content. Commercial anatase and rutile coated with curcumin (Cur-TiO2-an and Cur-TiO2-ru) were also prepared by the same method for the use in comparative studies of photodegradation of dyes. Cur-TiO2-an and Cur-TiO2-ru were also characterized with some selected equipment above but not as extensively as the Cur-TiO2-P25. Curcumin coating helped improve photocatalytic efficiencies of P25 and anatase but not for rutile. The mechanism of photocatalytic reaction was proposed that under visible light irradiation, curcumin molecule could act as dye sensitizing agent that injected electron into the conduction band of TiO2 leading to photodegradation of dyes.

Ti-in-zircon thermometry: applications and limitations

NASA Astrophysics Data System (ADS)

Fu, Bin; Page, F. Zeb; Cavosie, Aaron J.; Fournelle, John; Kita, Noriko T.; Lackey, Jade Star; Wilde, Simon A.; Valley, John W.

2008-08-01

The titanium concentrations of 484 zircons with U-Pb ages of ˜1 Ma to 4.4 Ga were measured by ion microprobe. Samples come from 45 different igneous rocks (365 zircons), as well as zircon megacrysts (84) from kimberlite, Early Archean detrital zircons (32), and zircon reference materials (3). Samples were chosen to represent a large range of igneous rock compositions. Most of the zircons contain less than 20 ppm Ti. Apparent temperatures for zircon crystallization were calculated using the Ti-in-zircon thermometer (Watson et al. 2006, Contrib Mineral Petrol 151:413-433) without making corrections for reduced oxide activities (e.g., TiO2 or SiO2), or variable pressure. Average apparent Ti-in-zircon temperatures range from 500° to 850°C, and are lower than either zircon saturation temperatures (for granitic rocks) or predicted crystallization temperatures of evolved melts (˜15% melt residue for mafic rocks). Temperatures average: 653 ± 124°C (2 standard deviations, 60 zircons) for felsic to intermediate igneous rocks, 758 ± 111°C (261 zircons) for mafic rocks, and 758 ± 98°C (84 zircons) for mantle megacrysts from kimberlite. Individually, the effects of reduced a_{TiO2} or a_{SiO2}, variable pressure, deviations from Henry’s Law, and subsolidus Ti exchange are insufficient to explain the seemingly low temperatures for zircon crystallization in igneous rocks. MELTs calculations show that mafic magmas can evolve to hydrous melts with significantly lower crystallization temperature for the last 10-15% melt residue than that of the main rock. While some magmatic zircons surely form in such late hydrous melts, low apparent temperatures are found in zircons that are included within phenocrysts or glass showing that those zircons are not from evolved residue melts. Intracrystalline variability in Ti concentration, in excess of analytical precision, is observed for nearly all zircons that were analyzed more than once. However, there is no systematic change in Ti content from core to rim, or correlation with zoning, age, U content, Th/U ratio, or concordance in U-Pb age. Thus, it is likely that other variables, in addition to temperature and a_{TiO2}, are important in controlling the Ti content of zircon. The Ti contents of igneous zircons from different rock types worldwide overlap significantly. However, on a more restricted regional scale, apparent Ti-in-zircon temperatures correlate with whole-rock SiO2 and HfO2 for plutonic rocks of the Sierra Nevada batholith, averaging 750°C at 50 wt.% SiO2 and 600°C at 75 wt.%. Among felsic plutons in the Sierra, peraluminous granites average 610 ± 88°C, while metaluminous rocks average 694 ± 94°C. Detrital zircons from the Jack Hills, Western Australia with ages from 4.4 to 4.0 Ga have apparent temperatures of 717 ± 108°C, which are intermediate between values for felsic rocks and those for mafic rocks. Although some mafic zircons have higher Ti content, values for Early Archean detrital zircons from a proposed granitic provenance are similar to zircons from many mafic rocks, including anorthosites from the Adirondack Mts (709 ± 76°C). Furthermore, the Jack Hills zircon apparent Ti-temperatures are significantly higher than measured values for peraluminous granites (610 ± 88°C). Thus the Ti concentration in detrital zircons and apparent Ti-in-zircon temperatures are not sufficient to independently identify parent melt composition.

Thermophysical, Electrical, and Optical Properties of Selected Metal-Nonmetal Transition Materials: Comprehensive Bibliography with Typical Data.

DTIC Science & Technology

1978-02-01

B.F., "High-Temperature Heat Contents of TiO, T12 03, Ti 30 5 , and TiO 2 ," J. Amer. Chem. Soc., 68, 1077-80, 1946. T006664. Vest, R.W., Griffel , M...Heats at Low Temperatures of Til, Ti20 3, Ti 305, and TiN," J. Amer. Chem. Soc., 68, 310-2, 1946. T008416. Vest, R.W., Griffel , M., and Smith, J.F., "Heat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ostapenko, Marina G., E-mail: artifakt@ispms.tsc.ru; Meisner, Ludmila L., E-mail: llm@ispms.tsc.ru; Lotkov, Aleksandr I., E-mail: lotkov@ispms.tsc.ru, E-mail: egu@ispms.tsc.ru

In the work, we study the mechanisms of structural phase state formation in NiTi surface layers after low-energy pulsed electron beam irradiation depending on the electron beam energy density. It is revealed that after electron beam treatment of the NiTi specimens at energy densities E{sub 1} = 15 J/cm{sup 2}, E{sub 2} = 20 J/cm{sup 2}, and E{sub 3} = 30 J/cm{sup 2}, a series of effects is observed: the absence of the Ti2Ni phase and the presence of new peaks correspond to the B19′ martensite phase with monoclinic structure. Estimation of the relative volume content of the B2 andmore » B19′ phases from the total intensity of their peaks shows that the percentage of the martensite phase increases from ∼5 vol.% in the NiTi specimen irradiated at E{sub 1} = 15 J/cm{sup 2} to ∼80 vol.% in the NiTi specimen irradiated at E{sub 3} = 30 J/cm{sup 2}. It is found that in the NiTi specimens irradiated at E ≤ 20 J/cm{sup 2}, the layer that contains a martensite phase resides not on the surface but at some depth from it.« less

Unification of the negative electrocaloric effect in Bi{sub 1/2}Na{sub 1/2}TiO{sub 3}-BaTiO{sub 3} solid solutions by Ba{sub 1/2}Sr{sub 1/2}TiO{sub 3} doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uddin, Sarir; Materials Research Laboratory, Institute of Physics and Electronics, University of Peshawar, Peshawar 25120; Zheng, Guang-Ping, E-mail: mmzheng@polyu.edu.hk

2013-12-07

The microscopic mechanisms of the negative electrocaloric effect (ECE) of the single-phase (1−x)(0.94Bi{sub 1/2}Na{sub 1/2}TiO{sub 3}-0.06BaTiO{sub 3})-xBa{sub 1/2}Sr{sub 1/2}TiO{sub 3} (BNT-BT-BST) perovskite solid solutions fabricated via the sol-gel technique are explored in this study. Dielectric and mechanical relaxation analyses are employed to investigate the ferroelectric and structural transitions of the samples. The electrocaloric properties of the samples were measured by thermodynamics Maxwell relations. The difference between the depolarization temperature (T{sub d}) and the maximum dielectric constant temperature (T{sub m}) was found to decrease with increasing BST content. Doping with BST stabilized the ferroelectric phase along with unifying the EC temperaturemore » changes (ΔT) to only negative values. The origin of the uniform negative ECE of BNT-BT-BST is discussed.« less

Effect of TiO2-Crystal Forms on the Photo-Degradation of EVA/PLA Blend Under Accelerated Weather Testing

NASA Astrophysics Data System (ADS)

Van Cong, Do; Trang, Nguyen Thi Thu; Giang, Nguyen Vu; Lam, Tran Dai; Hoang, Thai

2016-05-01

Photo-degradation of poly (ethylene-co-vinyl acetate) (EVA)/poly (lactic acid) (PLA) blend and EVA/PLA/TiO2 nanocomposites was carried out under accelerated weather testing conditions by alternating cycles of ultraviolet (UV) light and moisture at controlled and elevated temperatures. The characters, properties, and morphology of these materials before and after accelerated weather testing were determined by Fourier transform infrared spectroscopy, colour changes, viscosity, tensile test, thermogravimetric analysis, and field emission scanning electron microscopy. The increases in the content of oxygen-containing groups, colour changes; the decreases in viscosity, tensile properties, and thermal stability of these materials after accelerated weather testing are the evidence for the photo-degradation of the blend and nanocomposites. After accelerated weather testing, the appearance of many micro-holes and micro-pores on the surface of the collected samples was observed. The photo-degradation degree of the nanocomposites depended on the TiO2-crystal form. Rutile TiO2 do not enhance the degradation, but anatase and mixed crystals TiO2 nanoparticles promoted the degradation of the nanocomposites. Particularly, the mixed crystals TiO2 nanoparticles showed the highest photo-catalytic activity of the nanocomposites.

Effect of La-substitution on the structure, dielectric and ferroelectric properties of Nb modified SrBi{sub 8}Ti{sub 7}O{sub 27} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parida, Geetanjali, E-mail: geeta.lily@gmail.com; Bera, J., E-mail: jbera@nitrkl.ac.in

2015-08-15

Graphical abstract: The ferroelectric properties of Nb modified Bi{sub 4}Ti{sub 3}O{sub 12}–SrBi{sub 4}Ti{sub 4}O{sub 15} intergrowth ceramics increases significantly when Bi is substituted by La. - Highlights: • La{sup 3+} substitution for Bi{sup 3+} in Nb doped Bi{sub 4}Ti{sub 3}O{sub 12}–SrBi{sub 4}Ti{sub 4}O{sub 15} ferroelectrics is reported. • The orthorhombic distortion of the structure decreased with the increasing La. • La acts as a grain growth inhibitor in the ceramics. • The remnant polarization of the ferroelectrics increased significantly with La substitution. - Abstract: The effect of La substitution on the electrical properties of SrLa{sub x}Bi{sub 8−x}Ti{sub 6.88}Nb{sub 0}.{sub 12}O{submore » 27} intergrowth Aurivillius phase ferroelectric ceramic was investigated. La content ‘x’ was ranging from 0.0 to 1.0 in a step of 0.2. The ceramic phase was synthesized through a modified oxalate route. X-ray diffraction was used to identify the phase and to investigate the change in lattice parameter and microstrain with the substitution. La-substitution does not affect the crystal structure of the intergrowth. Microstructural investigation revealed that the grain size of the ceramic decreases with La addition. The lattice parameters and orthorhombicity of intergrowth structure were found to decrease with increasing La substitution. The temperature dependence of dielectric behavior was investigated in the temperature range 30–700 °C and the frequency of 100 kHz. The remnant polarization 2P{sub r} increased and the Curie temperature T{sub c} decreased with the increase in the La substitution.« less

Influence of Algae Age and Population on the Response to TiO₂ Nanoparticles.

PubMed

Metzler, David M; Erdem, Ayca; Huang, Chin Pao

2018-03-25

This work shows the influence of algae age (at the time of the exposure) and the initial algae population on the response of green algae Raphidocelis subcapitata to titanium dioxide nanoparticles (TiO₂ NPs). The different algae age was obtained by changes in flow rate of continually stirred tank reactors prior to NP exposure. Increased algae age led to a decreased growth, variations in chlorophyll content, and an increased lipid peroxidation. Increased initial algae population (0.3-4.2 × 10⁶ cells/mL) at a constant NP concentration (100 mg/L) caused a decline in the growth of algae. With increased initial algae population, the lipid peroxidation and chlorophyll both initially decreased and then increased. Lipid peroxidation had 4× the amount of the control at high and low initial population but, at mid-ranged initial population, had approximately half the control value. Chlorophyll a results also showed a similar trend. These results indicate that the physiological state of the algae is important for the toxicological effect of TiO₂ NPs. The condition of algae and exposure regime must be considered in detail when assessing the toxicological response of NPs to algae.

Influence of Algae Age and Population on the Response to TiO2 Nanoparticles

PubMed Central

Metzler, David M.; Erdem, Ayca; Huang, Chin Pao

2018-01-01

This work shows the influence of algae age (at the time of the exposure) and the initial algae population on the response of green algae Raphidocelis subcapitata to titanium dioxide nanoparticles (TiO2 NPs). The different algae age was obtained by changes in flow rate of continually stirred tank reactors prior to NP exposure. Increased algae age led to a decreased growth, variations in chlorophyll content, and an increased lipid peroxidation. Increased initial algae population (0.3−4.2 × 106 cells/mL) at a constant NP concentration (100 mg/L) caused a decline in the growth of algae. With increased initial algae population, the lipid peroxidation and chlorophyll both initially decreased and then increased. Lipid peroxidation had 4× the amount of the control at high and low initial population but, at mid-ranged initial population, had approximately half the control value. Chlorophyll a results also showed a similar trend. These results indicate that the physiological state of the algae is important for the toxicological effect of TiO2 NPs. The condition of algae and exposure regime must be considered in detail when assessing the toxicological response of NPs to algae. PMID:29587381

Ion beam irradiation of lanthanum and thorium-doped yttrium titanates

NASA Astrophysics Data System (ADS)

Lian, J.; Zhang, F. X.; Peters, M. T.; Wang, L. M.; Ewing, R. C.

2007-05-01

Y2Ti2O7 pyrochlores doped with La have been sintered at 1373 K for 12 h with the designed compositions of the (LaxY1-x)2Ti2O7 system (x = 0, 0.08, 0.5, and 1), and the phase compositions were analyzed by X-ray diffraction. Limited amounts of La were incorporated into yttrium titanate pyrochlore structure for La-doped samples; while, the end member composition of La2Ti2O7 formed a layered perovskite structure. Ion beam-induced amorphization occurred for all compositions in the (LaxY1-x)2Ti2O7 binary under 1 MeV Kr2+ irradiation at room temperature, and the critical amorphization dose decreased with increasing amounts of La3+. The critical amorphization temperatures for Y2Ti2O7, (La0.162Y0.838)2Ti2O7 and La2Ti2O7 were determined to be ∼780, 890 and 920 K, respectively. Th4+ and Fe3+-doped yttrium titanate pyrochlores were synthesized at 1373 K by sintering Y2Ti2O7 with (ThO2 + Fe2O3). Pyrochlore structures and the chemical compositions were primarily identified by the X-ray diffraction and energy dispersive X-ray (EDX) measurements. The lattice parameter and the critical amorphization dose (1 MeV Kr2+ at room temperature) increase for yttrium titanate pyrochlores with the addition of Th. The increasing 'resistance' to amorphization with less La and greater Th and Fe contents for (Y1-xLax)2Ti2O7 and Y2Ti2O7-Fe2O3-ThO2 systems, respectively, are consistent with the changes in the average ionic radius ratio at the A-sites and B-sites. These results suggest that the addition of lanthanides and actinides (e.g., Th, U, or Pu) will affect the structural stability, as well as the radiation response behavior of the pyrochlore structure-type.

Preparation and characterization of Al{sub 2}O{sub 3}-Ti{sub 3}SiC{sub 2} composites and its functionally graded materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo Yongming; Li Shuqin; Chen Jian

2003-01-01

Alumina/titanium silicon carbide (Al{sub 2}O{sub 3}-Ti{sub 3}SiC{sub 2}) composites and its functionally graded materials (FGMs) were fabricated by a powder metallurgy processes and their microstructure and properties were investigated, respectively. The experimental results showed that the Vickers hardness of composites decreased with increasing Ti{sub 3}SiC{sub 2} content while the fracture toughness and strength exhibited the opposite trend. Minimum Vickers hardness (4 GPa), maximum strength (598 MPa) and maximum toughness (11.24 MPa m{sup 1/2}) were reached in the pure Ti{sub 3}SiC{sub 2} material. Strength and hardness of FGMs were evaluated. Observation using an scanning electron microscope (SEM) indicated that the presencemore » of Ti{sub 3}SiC{sub 2} of FGMs inhibited the growth of alumina grains through a pinning mechanism. The study shows that the combination of the layered Ti{sub 3}SiC{sub 2} structure and the fine alumina grains can result in a Al{sub 2}O{sub 3}-Ti{sub 3}SiC{sub 2} composites possessing a high toughness and low Vickers hardness without a sacrifice in the strength.« less

Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

NASA Astrophysics Data System (ADS)

Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

2014-12-01

Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

Porous Ba0.85Ca0.15Zr0.1Ti0.9O3 Ceramics for Pyroelectric Applications

NASA Astrophysics Data System (ADS)

Sharma, Moolchand; Singh, V. P.; Singh, Shatrughan; Azad, Puneet; Ilahi, Bouraoui; Madhar, Niyaz Ahamad

2018-05-01

Porous Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ferroelectric ceramics were fabricated using a solid-state reaction consisting of BCZT and poly(methyl methacrylate)(PMMA) (2%, 4%, 8% and 10% by wt.%) as a pore former. By increasing the PMMA content from 0% to 10%, porosity increased from 8% to 29%. It was found that the dielectric constant (ɛ r ) decreased and the dielectric loss (tanδ) increased with increasing porosity. At 29% porosity, ɛ r of the BCZT was found to decrease more, from 3481 to 1117 at 5 kHz and at room temperature. The dielectric constant and volume-specific heat capacity decreased with the increase in porosity which ultimately improved the pyroelectric figure-of-merits (FOMs). Further, the pyroelectric FOMs were estimated and found to be improved at optimum porosity.

Synergistic reinforcing effect of TiO2 and montmorillonite on potato starch nanocomposite films: Thermal, mechanical and barrier properties.

PubMed

Oleyaei, Seyed Amir; Almasi, Hadi; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

2016-11-05

In this study, ternary potato starch (PS) bionanocomposite films containing two types of nanoparticles, sodium montmorillonite (MMT), one-dimensional (1D) clay platelets, (3 and 5wt%) and TiO2, three-dimensional (3D) nanospheres, (0.5, 1 and 2wt%), are prepared using solvent casting method. X-ray diffraction (XRD) test confirms the completely exfoliated structure formed in the PS-MMT nanocomposites containing 3 and 5% MMT. The success of the formation of new hydrogen bonds between the hydroxyl groups of starch and nanofillers is confirmed by Fourier transform infrared (FTIR) spectroscopy. Tensile strength (TS), elongation at break (EB), glass transition temperature (Tg), and melting point (Tm) of the films are also enhanced after MMT and TiO2 incorporation. The water vapor permeability (WVP) and the visible, UVA, UVB and UVC lights transmittance decreases upon TiO2 and MMT content increasing. Generally, a synergistic effect is observed between MMT and TiO2 at lower concentrations of MMT. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanical properties of titanium-hydroxyapatite (Ti-HA) composite coating on stainless steel prepared by thermal spraying

NASA Astrophysics Data System (ADS)

Rosmamuhamadani, R.; Azhar, N. H.; Talari, M. K.; Yahaya, Sabrina M.; Sulaiman, S.; Ismail, M. I. S.

2017-09-01

Addition of hydroxyapatite (HA) can enhance the bioactivity of the common metallic implant due to its similarity with natural bones and teeth. In this investigation, high velocity oxy-fuel (HVOFT) technique was used to deposit titanium-hydroxyapatite (Ti-HA) composite on stainless steel substrate plate with different percentage of HA for biomedical applications. The aim of this research is to investigate the mechanical properties of Ti-HA coating such as hardness, adhesion strength and wear behaviour. The hardness and strength was determined by using SHIMADZU-microhardness Vickers tester and PosiTest AT portable adhesion tester respectively. The wear test was performed by using pin-on-disk equipment and field emission scanning electron microscope (FESEM) used to determine the extent of surface damage. From the results obtained, mechanical properties such as hardness and adhesion strength of titanium (Ti) coating decreased with the increased of HA contents. Meanwhile, the coefficient of friction of Ti-10% HA coating shows the highest value compare to others as three-body abrasion had occurred during the test.

Facile decoration of TiO2 nanoparticles on graphene for solar degradation of organic dye

NASA Astrophysics Data System (ADS)

Salem, Shiva; Salem, Amin; Rezaei, Mostafa

2016-11-01

The reduced graphene oxide is interesting material for the synthesis of TiO2-based photocatalyst. In the present investigation, blackberry fruit, which contains high levels of anthocyanins and other phenolic compounds, was employed as a reducing agent mainly due to its high antioxidant capacity. The nano-crystalline TiO2 was decorated on different amounts of graphene oxide with sol-gel method and then the photocatalytic activity for degradation of cationic dye was evaluated by UV spectroscopy to achieve the optimum content of graphene oxide. The decoration of anatase nanoparticles on prepared reduced graphene oxide was investigated by X-ray diffraction, scanning and transmission electron microscopy techniques. The new composite gives significantly higher activity when is compared to the compositions fabricated by graphene oxide. The compact layer provides a large TiO2-graphene contact area and reduces the electron recombination. The decoration of TiO2 nanoparticles, 5-10 nm, on the graphene oxide reduced by blackberry juice further improves the dye removal. The results imply that the nanoparticle decoration is the key strategy to increase the degradation capacity.

A rapid tool for determination of titanium dioxide content in white chickpea samples.

PubMed

Sezer, Banu; Bilge, Gonca; Berkkan, Aysel; Tamer, Ugur; Hakki Boyaci, Ismail

2018-02-01

Titanium dioxide (TiO 2 ) is a widely used additive in foods. However, in the scientific community there is an ongoing debate on health concerns about TiO 2 . The main goal of this study is to determine TiO 2 content by using laser induced breakdown spectroscopy (LIBS). To this end, different amounts of TiO 2 was added to white chickpeas and analyzed by using LIBS. Calibration curve was obtained by following Ti emissions at 390.11nm for univariate calibration, and partial least square (PLS) calibration curve was obtained by evaluating the whole spectra. The results showed that Ti calibration curve at 390.11nm provides successful determination of Ti level with 0.985 of R 2 and 33.9ppm of limit of detection (LOD) value, while PLS has 0.989 of R 2 and 60.9ppm of LOD. Furthermore, commercial white chickpea samples were used to validate the method, and validation R 2 for simple calibration and PLS were calculated as 0.989 and 0.951, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Dynamics of heavy metals in the holocene aeolian loess-soil profile in the upper-reaches of the Huaihe River].

PubMed

He, Zhong; Huang, Chun-chang; Pang, Jiang-li; Wang, Li-jun; Li, Xin-yan

2006-07-01

Upon the exploration and research in the field, we determined the content of Pb, Zn, Cu, Mn, Cr, Co, Ni, Ti, V, Nb at YPC loess-soil site on the X-ray Fluorescence. In the stage of loess accumulation, the content of these heavy metals are very low and the variances are very little, which can be served as the background value of paleosol formation. In the stage of Holocene Megathermal, the content of these heavy metals are increased greatly, because the eluviations and transmigrations of freely soluble elements under warm and humidity environment. In the stage of modern soil( MS), the content of Pb are increased gradually, and there are abruptly increase in the depth of 8cm below the ground, which are the records of sedimentation and accumulation of atmospheric pollutant.

Friction and wear with a single-crystal abrasive grit of silicon carbide in contact with iron base binary alloys in oil: Effects of alloying element and its content

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1979-01-01

Sliding friction experiments were conducted with various iron-base binary alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a rider of 0.025-millimeter-radius, single-crystal silicon carbide in mineral oil. Results indicate that atomic size and content of alloying element play a dominant role in controlling the abrasive-wear and -friction properties of iron-base binary alloys. The coefficient of friction and groove height (wear volume) general alloy decrease, and the contact pressure increases in solute content. There appears to be very good correlation of the solute to iron atomic radius ratio with the decreasing rate of coefficient of friction, the decreasing rate of groove height (wear volume), and the increasing rate of contact pressure with increasing solute content C. Those rates increase as the solute to iron atomic radius ratio increases from unity.

Current understanding of structure-processing-property relationships in BaTiO 3-Bi( M)O 3 dielectrics

DOE PAGES

Beuerlein, Michaela A.; Kumar, Nitish; Usher, Tedi -Marie; ...

2016-09-01

Here, as part of a continued push for high permittivity dielectrics suitable for use at elevated operating temperatures and/or large electric fields, modifications of BaTiO 3 with Bi( M)O 3, where M represents a net-trivalent B-site occupied by one or more species, have received a great deal of recent attention. Materials in this composition family exhibit weakly coupled relaxor behavior that is not only remarkably stable at high temperatures and under large electric fields, but is also quite similar across various identities of M. Moderate levels of Bi content (as much as 50 mol%) appear to be crucial to themore » stability of the dielectric response. In addition, the presence of significant Bi reduces the processing temperatures required for densification and increases the required oxygen content in processing atmospheres relative to traditional X7R-type BaTiO 3-based dielectrics. Although detailed understanding of the structure–processing–property relationships in this class of materials is still in its infancy, this article reviews the current state of understanding of the mechanisms underlying the high and stable values of both relative permittivity and resistivity that are characteristic of BaTiO 3-Bi( M)O 3 dielectrics as well as the processing challenges and opportunities associated with these materials.« less

The role of nicotine, cotinine and caffeine on the electrochemical behavior and bacterial colonization to cp-Ti.

PubMed

Barão, Valentim A R; Ricomini-Filho, Antonio P; Faverani, Leonardo P; Del Bel Cury, Altair A; Sukotjo, Cortino; Monteiro, Douglas R; Yuan, Judy Chia-Chun; Mathew, Mathew T; do Amaral, Regiane C; Mesquita, Marcelo F; da Silva, Wander J; Assunção, Wirley G

2015-11-01

Although smoking promotes deleterious effect to bone healing, there is a lack of study investigating its role on the implant structure and biofilm growth. We hypothesized that nicotine, cotinine and caffeine would impair the corrosion resistance of commercially-pure titanium (cp-Ti) and would enhance Streptococcus sanguinis biofilm growth. Neither the smoking products nor the caffeine affected the corrosion tendency (P>.05) and the oxide layer resistance (P=.762) of cp-Ti. Lower capacitance values were noted in the presence of nicotine (P=.001) and cotinine (P=.0006). SEM showed no pitting corrosion, and the EDS spectra did not differ among groups. Nicotine (300μg/mL) induced higher surface roughness (P=.03) and greater surface change of cp-Ti. Nicotine at 3μg/mL, and cotinine at 0.3 and 3μg/mL increased the number of viable cells (P<.05). Biofilm exposed to nicotine (0.3, 3 and 30μg/mL) (P=.025, .030, .040, respectively) and cotinine (3 and 30μg/mL) (P=.027, .049, respectively) enhanced carbohydrate content. Biofilm biomass and protein content were similar among groups (P>.05). These findings suggest a greater biofilm accumulation in smokers, a risk factor that may lead to peri-implantitis. Copyright © 2015 Elsevier B.V. All rights reserved.

Study of the structure, dielectric and ferroelectric behavior of BaBi{sub 4+δ}Ti{sub 4}O{sub 15} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khokhar, Anita, E-mail: mails4anita@gmail.com, E-mail: goyalphy@gmail.com; Goyal, Parveen K., E-mail: mails4anita@gmail.com, E-mail: goyalphy@gmail.com; Sreenivas, K.

2016-05-23

The structure and ferroelectric properties of excess bismuth doped barium bismuth titanate BaBi{sub 4+δ}Ti{sub 4}O{sub 15} (δ = 2 - 10 wt.%)) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material with a change in the orthorhombic distortion with varying excess of bismuth content. There is no change in the phase transition temperature (T{sub m}) while the relaxor behaviour has been modified significantly with excess of bismuth doping. Saturated hysteresis loops with high remnant polarization (P{sub r} ~ 12.5  µC/cm{sup 2}), low coercive fields (E{sub c} ~ 26 kV/cm) aremore » measured and a high piezoelectric coefficient (d{sub 33} ~ 29 pC/N) is achieved in poled BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics prepared with up to 8 wt.% of excess bismuth oxide. The improvement in the ferroelectric properties with increase in the excess bismuth content in BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of excess bismuth.« less

Synthesis of Ti-Ta alloys with dual structure by incomplete diffusion between elemental powders.

PubMed

Liu, Yong; Li, Kaiyang; Wu, Hong; Song, Min; Wang, Wen; Li, Nianfeng; Tang, Huiping

2015-11-01

In this work, powder metallurgical (PM) Ti-Ta alloys were sintered using blended elemental powders. A dual structure, consisting of Ti-rich and Ta-rich zones, was formed due to the insufficient diffusion between Ti and Ta powders. The microstructure, mechanical properties and in vitro biological properties of the alloys were studied. Results indicated that the alloys have inhomogenous microstructures and compositions, but the grain structures were continuous from the Ti-rich zone to the Ta-rich zone. The Ta-rich zone exhibited a much finer grain size than the Ti-rich zone. The alloys had a high relative density in the range of 95-98%, with the porosity increasing with the content of Ta due to the increased difficulty in sintering and the formation of Kirkendall pores. The alloys had a good combination of low elastic modulus and high tensile strength. The strength of alloys was almost doubled compared to that of the ingot metallurgy alloys with the same compositions. The low elastic modulus was due to the residual pores and the alloying effect of Ta, while the high tensile strength resulted from the strengthening effects of solid solution, fine grain size and α phase. The alloys had a high biocompatibility due to the addition of Ta, and were suitable for the attachment of cells due to the surface porosity. It was also indicated that PM Ti-(20-30)Ta alloys are promising for biomedical applications after the evaluations of both the mechanical and the biological properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fabrication of Li2TiO3 pebbles using PVA-boric acid reaction for solid breeding materials

NASA Astrophysics Data System (ADS)

Park, Yi-Hyun; Cho, Seungyon; Ahn, Mu-Young

2014-12-01

Lithium metatitanate (Li2TiO3) is a candidate breeding material of the Helium Cooled Ceramic Reflector (HCCR) Test Blanket Module (TBM). The breeding material is used in pebble-bed form to reduce the uncertainty of the interface thermal conductance. In this study, Li2TiO3 pebbles were successfully fabricated by the slurry droplet wetting method using the cross-linking reaction between polyvinyl alcohol (PVA) and boric acid. The effects of fabrication parameters on the shaping of Li2TiO3 green body were investigated. In addition, the basic characteristics of the sintered pebble were also evaluated. The shape of Li2TiO3 green bodies was affected by slurry viscosity, PVA content and boric acid content. The grain size and average crush load of sintered Li2TiO3 pebble were controlled by the sintering time. The boron was completely removed during the final sintering process.

Structure and phase formation behavior and dielectric and magnetic properties of lead iron tantalate-lead zirconate titanate multiferroic ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wongmaneerung, R., E-mail: re_nok@yahoo.com; Tipakontitikul, R.; Jantaratana, P.

2016-03-15

Highlights: • The multiferroic ceramics consisted of PFT and PZT. • Crystal structure changed from cubic to mixedcubic and tetragonal with increasing PZT content. • Dielectric showed the samples underwent a typical relaxor ferroelectric behavior. • Magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops. - Abstract: Multiferroic (1 − x)Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3}–xPb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3} (or PFT–PZT) ceramics were synthesized by solid-state reaction method. The crystal structure and phase formation of the ceramics were examined by X-ray diffraction (XRD). The local structure surrounding Fe and Ti absorbing atoms was investigated by synchrotron X-ray Absorption Near-Edgemore » Structure (XANES) measurement. Dielectric properties were studied as a function of frequency and temperature using a LCR meter. A vibrating sample magnetometer (VSM) was used to determine the magnetic hysteresis loops. XRD study indicated that the crystal structure of the sample changed from pure cubic to mixed cubic and tetragonal with increasing PZT content. XANES measurements showed that the local structure surrounding Fe and Ti ions was similar. Dielectric study showed that the samples underwent a typical relaxor ferroelectric behavior while the magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops.« less

TiO2 Nanorods Preparation from Titanyl Sulphate Produced by Dissolution of Ilmenite

NASA Astrophysics Data System (ADS)

Wahyuningsih, S.; Rinawati, L.; Munifa, R. M. I.; Ramelan, A. H.; Sulistyono, Eko

2017-02-01

One-dimensional titanium oxides (TiO2) nanorods have substantial applications in photocatalytic, nanoelectronic, and photoelectrochemical solar cells. These applications require large quantities of materials and a production technique suitable for future industry fabrication. We demonstrate here a new method of TiO2 nanorods production from ilmenite sands (FeTiO3). In this process, the roasted ilmenite sand was separated from the iron content and dissolved in the sulphuric acid solution. Separation process of TiO2 from ilmenite has been carried out by roasting, leaching and precipitation processes. The roasting process was conducted by the addition of Na2S at a temperature of 800°C that had been deomposed ilmenite into hematite (Fe2O3), anatase TiO2, rutile TiO2, Na2SO4, NaFeS2 and NaFeO2. Separation TiO2 from titanyl sulfate (TiOSO4) after leaching in H2SO4 solution was conducted by hydrolysis-condensation step and complexation step of Fe2+ content. KCNS solution was used as a complexing agent. The xerogel synthesized TiO2 then was prepared to 1-D nanostructure of TiO2 nanorods by hydrothermal process under alkaline condition. By the two-step method, we finally gain the 1D nanorods TiO2 extracted from ilmenite sand. The characterization using the Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) obtained the nanorod morphology at a diameter about 9.6 nm.

Photochemically deposited nano-Ag/sol-gel TiO2-In2O3 mixed oxide mesoporous-assembled nanocrystals for photocatalytic dye degradation.

PubMed

Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

2014-05-01

This work focused on the improvement of the photocatalytic activity for Congo Red (CR) azo dye degradation of mesoporous-assembled 0.95 TiO2-0.05 In2O3 mixed oxide photocatalyst (with a TiO2-to-In2O3 molar ratio of 0.95:0.05) by loading with Ag nanoparticles. The mesoporous-assembled 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was synthesized by a hydrolytic sol-gel method with the aid of a structure-directing surfactant, prior to loading with various Ag contents (0.5-2 wt.%) by a photochemical deposition method. The optimum Ag loading content was found to be 1.5 wt.%, exhibiting a great increase in photocatalytic CR dye degradation activity. The 1.5 wt.% Ag-loaded 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was further applied for the CR dye degradation in the presence of water hardness. Different types (Ca2+ and Ca2+ -Mg2+ mixture) and concentrations (200 and 500 mg/l) of water hardness were investigated. The results showed that the water hardness reduced the photocatalytic CR dye degradation activity, particularly for the extremely hard water with 500 mg/l of Ca2+ -Mg2+ mixture. The adjustment of initial solution pH of the CR dye-containing hard water to an appropriate value was found to improve the photocatalytic CR dye degradation activity under the identical reaction conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

Photoreduction of Carbon Dioxide to Methane Over Sb1.5Sn8.5-x Ti x O19.0 with High Conductivity.

PubMed

Do, Jeong Yeon; Kwak, Byeong Sub; Kang, Misook

2018-09-01

In order to enhance the photoreduction of CO2 to CH4, a new type of photocatalyst, Sb1.5Sn8.5-xTixO19.0, with high conductivity and low bandgap was developed by partially incorporating Ti into the framework of Sb1.5Sn8.5O19.0 (antimony-doped tin oxide, ATO) using a controlled hydrothermal method. XRD and TEM analyses indicated that the Sb1.5Sn8.5-xTixO19.0 particles exhibited a tetragonal crystal structure and were approximately 20 nm in size. Furthermore, the bandgap and conductivity of these materials increased with increasing Ti content. A study of the photoreduction of CO2 with H2O revealed a remarkable increase in the generation of CH4 over the Sb1.5Sn8.5-xTixO19.0 catalysts. In particular, CH4 generation was the highest when Sb1.5Sn8.5Ti1.0O19.0 was used as the photocatalyst, and was three-fold higher than that achieved by using anatase TiO2. Photoluminescence studies showed that the enhanced photocatalytic activity of the Sb1.5Sn8.5-xTixO19.0 materials could be attributed to the interfacial transfer of photogenerated charges, which led to an effective charge separation and inhibition of the recombination of photogenerated electron-hole (e-/h+) pairs.

TGF-beta1 secretion of ROS-17/2.8 cultures on NiTi implant material.

PubMed

Kapanen, Anita; Kinnunen, Anne; Ryhänen, Jorma; Tuukkanen, Juha

2002-08-01

The biocompatibility of an orthopedic implant depends on the effect of the implant on bone-forming cells, osteoblasts. Changes in osteoblastic proliferation, maturation and differentiation are important events in ossification that enable monitoring the effect of the implant. Transforming growth factor-beta (TGF-beta) is known to suppress osteoblast proliferation and, on the other hand, to induce the maturation and differentiation of osteoblasts. Moreover, osteoblasts produce TGF-beta, which is embedded in the bone matrix and activated by bone-resorbing osteoclasts. TGF-beta inhibits osteoclastic activity. Here, we show for the first time the effect of nickel titanium shape memory metal (NiTi) on osteoblastic cytokine expression. In this study, we measured the levels of TGF-beta with enzyme-linked immunosorbent assay (ELISA) from a ROS-17/2.8 osteosarcoma cell line cultured on different metal alloy discs. ELISA results were proportioned to total DNA content of the samples. We compared NiTi, to stainless steel (Stst), pure titanium (Ti) and pure nickel (Ni). The TGF-beta1/DNA value in the NiTi group (0.0007 +/- 0.0003) was comparable with those seen in the Stst (0.0008 +/- 0.0001) and Ti (0.0007 +/- 0.0001) groups. The concentration in the Ni group was lower (0.0006 +/- 0.0003), though not statistically significantly so. In addition, the effect of surface roughness on TGF-beta1 production was studied. We compared three different grades of roughness in three differently hot-rolled alloys: NiTi. hot-rolled at 950 degrees C. Ti alloy hot-rolled at 850 degrees C (TiI) and the same Ti alloy hot-rolled at 1,050 degrees C (TiII). We found that increasing roughness of the NiTi surface increased the TGF-beta1 concentration. On the other hand, all roughness groups of TiII showed low levels of TGF-beta1. while a rough TiI surface induced similar TGF-beta1, expression as rough NiTi. Further, these same measurements made with interleukine 6 (IL-6) were found to be under the detection limit in these cultures. We conclude that a rough NiTi surface promotes TGF-beta1 expression in ROS-17/2.8 cells.

Effect of oxygen concentration and metal electrode on the resistive switching in MIM capacitors with transition metal oxides

NASA Astrophysics Data System (ADS)

Spassov, D.; Paskaleva, A.; Fröhlich, K.; Ivanov, Tz

2017-01-01

The influence of the oxygen content in the dielectric layer and the effect of the bottom electrode on the resistive switching in Au/Pt/TaOx/TiN and Au/Pt/TaOx/Ta structures have been studied. The sputtered TaOx layers have been prepared by using oxygen concentrations of 10 or 7% O 2 in the Ar+O2 working ambient as well as by a gradual variation of the O2 content in the deposition process from 5 to 10%. Two deposition regimes for TiN electrodes have been investigated: reactive sputtering of Ti target in Ar+N2 ambient, and sputtering of TiN target in pure Ar. Bipolar resistive switching behavior is observed in all examined structures. It is demonstrated that the resistive switching effect is affected by the oxygen content in the working ambient as well as by the type and the deposition conditions of the bottom electrodes. Most stable effect, with ON/OFF ratio above 100 is obtained in TaOx deposited with variable O2 content in the ambient. The obtained switching voltage between the high resistive and low resistive state (SET) is about -1.5 V and the reverse changeover (RESET) is ∼2 V. A well pronounced resistive switching is achieved with reactively sputtered TiN while for the other bottom electrodes the effect is negligible.

Grain Refinement of Al-Si Hypoeutectic Alloys by Al3Ti1B Master Alloy and Ultrasonic Treatment

NASA Astrophysics Data System (ADS)

Wang, Gui; Wang, Eric Qiang; Prasad, Arvind; Dargusch, Matthew; StJohn, David H.

Al-Si alloys are widely used in automotive and aerospace industries due to their excellent castability, high strength to weight ratio and good corrosion resistance. However, Si poisoning severely limits the degree of grain refinement with the grain size becoming larger as the Si content increases. Generally the effect of Si poisoning is reduced by increasing the amount of master alloy added to the melt during casting. However, an alternative approach is physical grain refinement through the application of an external force (e.g. mechanical or electromagnetic stirring, intensive shearing and ultrasonic irradiation). This work compares the grain refining efficiency of three approaches to the grain refinement of a range of hypoeutectic Al-Si alloys by (i) the addition of A13Ti1B master alloy, (ii) the application of Ultrasonic Treatment (UT) and (iii) the combined addition of A13Ti1B master alloy and the application of UT.

Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

PubMed Central

Ning, Xuewen; Wang, Xixin; Yu, Xiaofei; Zhao, Jianling; Wang, Mingli; Li, Haoran; Yang, Yang

2016-01-01

Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm2 at a current density of 3 mA/cm2 when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm2, and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work. PMID:26940546

Effects of Electric Discharge Plasma Treatment on the Thermal Conductivity of Polymer-Metal Nitride/Carbide Composites

NASA Astrophysics Data System (ADS)

Parali, Levent; Kurbanov, Mirza A.; Bayramov, Azad A.; Tatardar, Farida N.; Sultanakhmedova, Ramazanova I.; Xanlar, Huseynova Gulnara

2015-11-01

High-density polymer composites with semiconductor or dielectric fillers such as aluminum nitride (AIN), aluminum oxide (Al2O3), titanium carbide (TiC), titanium nitride (TiN), boron nitride (BN), silicon nitride (Si3N4), and titanium carbonitride (TiCN) were prepared by the hot pressing method. Each powder phase of the composites was exposed to an electric discharge plasma process before composite formation. The effects of the electric discharge plasma process and the filler content (volume fraction) on the thermal conductivity, volt-ampere characteristics, thermally stimulated depolarization current, as well as electrical and mechanical strength were investigated. The results of the study indicate that, with increasing filler volume fraction, the thermal conductivity of the samples also increased. Furthermore, the thermal conductivity, and electrophysical and mechanical properties of the high-density polyethylene + 70% BN composite modified using the electric discharge plasma showed improvement when compared with that without electric discharge plasma treatment.

Application of sintered titanium alloys to metal denture bases: a study of titanium powder sheets for complete denture base.

PubMed

Doi, H; Harrori, M; Hasegawa, K; Yoshinari, M; Kawada, E; Oda, Y

2001-02-01

The purpose of this study was the fabrication of titanium powder sheets to enable the application of sintered titanium alloys as metal denture bases. The effects of titanium particle shape and size, binder content, and plasticizer content on the surface smoothness, tensile strength and elongation of titanium powder sheets was investigated. To select a suitable ratio of powdered metal contents for application as a metal denture base, the effects of aluminum content in Ti sheets and various other powder metal contents in Ti-Al sheets on the density, sintering shrinkage, and bending strength were evaluated. Based on the results of the above experiments, we developed a mixed powder sheet composed of 83Ti-7Al-10Cr with TA45 titanium powder (atomized, -45 microm), and 8 mass% binder content. This titanium alloy sheet had good formability and ductility. Its sintered titanium alloy had a density of 3.2 g/cm3, sintering shrinkage of 3.8%, and bending strength of 403 MPa. The titanium alloy sheet is clinically acceptable for fabricating denture bases.

Variations of trace element concentration of magnetite and ilmenite from the Taihe layered intrusion, Emeishan large igneous province, SW China: Implications for magmatic fractionation and origin of Fe-Ti-V oxide ore deposits

NASA Astrophysics Data System (ADS)

She, Yu-Wei; Song, Xie-Yan; Yu, Song-Yue; He, Hai-Long

2015-12-01

In situ LA-ICP-MS trace elemental analysis has been applied to magnetite and ilmenite of the Taihe layered intrusion, Emeishan large igneous province, SW China, in order to understand better fractionation processes of magma and origin of Fe-Ti-V oxide ore deposits. The periodic reversals in Mg, Ti, Mn in magnetite and Mg, Sc in ilmenite are found in the Middle Zone of the intrusion and agree with fractionation trends as recorded by olivine (Fo), plagioclase (An) and clinopyroxene (Mg#) compositions. These suggest the Taihe intrusion formed from open magma chamber processes in a magma conduit with multiple replenishments of more primitive magmas. The V and Cr of magnetite are well correlated with V and Cr of clinopyroxene indicating that they became liquidus phases almost simultaneously at an early stage of magma evolution. Ilmenite from the Middle and Upper Zones shows variable Cr, Ni, V, Mg, Nb, Ta and Sc contents indicating that ilmenite at some stratigraphic levels crystallized slightly earlier than magnetite and clinopyroxene. The early crystallization of magnetite and ilmenite is the result of the high FeOt and TiO2 contents in the parental magma. The ilmenite crystallization before magnetite in the Middle and Upper Zones can be attributed to higher TiO2 content of the magma due to the remelting of pre-existing ilmenite in a middle-level magma chamber. Compared to the coeval high-Ti basalts, the relatively low Zr, Hf, Nb and Ta contents in both magnetite and ilmenite throughout the Taihe intrusion indicate that they crystallized from Fe-Ti-(P)-rich silicate magmas. Positive correlations of Ti with Mg, Mn, Sc and Zr of magnetite, and Zr with Sc, Hf and Nb of ilmenite also suggest that magnetite and ilmenite crystallized continuously from the homogeneous silicate magma rather than an immiscible Fe-rich melt. Therefore, frequent replenishments of Fe-Ti-(P)-rich silicate magma and gravitational sorting and settling are crucial for the formation the massive and apatite-rich disseminated ores in the Lower and Middle Zones of the Taihe intrusion.

Reactive wetting properties of TiO2 nanoparticles predicted by ab initio molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Brandt, Erik G.; Agosta, Lorenzo; Lyubartsev, Alexander P.

2016-07-01

Small-sized wet TiO2 nanoparticles have been investigated by ab initio molecular dynamics simulations. Chemical and physical adsorption of water on the TiO2-water interface was studied as a function of water content, ranging from dry nanoparticles to wet nanoparticles with monolayer coverage of water. The surface reactivity was shown to be a concave function of water content and driven by surface defects. The local coordination number at the defect was identified as the key factor to decide whether water adsorption proceeds through dissociation or physisorption on the surface. A consistent picture of TiO2 nanoparticle wetting at the microscopic level emerges, which corroborates existing experimental data and gives further insight into the molecular mechanisms behind nanoparticle wetting. These calculations will facilitate the engineering of metal oxide nanoparticles with a controlled catalytic water activity.Small-sized wet TiO2 nanoparticles have been investigated by ab initio molecular dynamics simulations. Chemical and physical adsorption of water on the TiO2-water interface was studied as a function of water content, ranging from dry nanoparticles to wet nanoparticles with monolayer coverage of water. The surface reactivity was shown to be a concave function of water content and driven by surface defects. The local coordination number at the defect was identified as the key factor to decide whether water adsorption proceeds through dissociation or physisorption on the surface. A consistent picture of TiO2 nanoparticle wetting at the microscopic level emerges, which corroborates existing experimental data and gives further insight into the molecular mechanisms behind nanoparticle wetting. These calculations will facilitate the engineering of metal oxide nanoparticles with a controlled catalytic water activity. Electronic supplementary information (ESI) available: Simulation data on equilibration of energies and structures (root-mean-square-deviations and coordination numbers); radial distribution functions for all O-Ti pairs over the entire data domain; comparison of coordination number distributions for dry and wet nanoparticles; dynamics of water reactivity; high-resolution electron density for the rutile NP. A movie of the simulation trajectory for the rutile (TiO2)24.30H2O system. See DOI: 10.1039/C6NR02791A

Role of Fe doping in tuning the band gap of TiO2 for photo-oxidation induced cytotoxicity paradigm

PubMed Central

George, Saji; Pokhrel, Suman; Ji, Zhaoxia; Henderson, Bryana L.; Xia, Tian; Li, LinJiang; Zink, Jeffrey I.; Nel, André E.; Mädler, Lutz

2014-01-01

UV-Light induced electron-hole (e−/h+) pair generation and free radical production in TiO2 based nanoparticles is a major conceptual paradigm for biological injury. However, to date, this hypothesis has been difficult to experimentally verify due to the high energy of UV light that is intrinsically highly toxic to biological systems. Here, a versatile flame spray pyrolysis (FSP) synthetic process has been exploited to synthesize a library of iron doped (0–10 at wt%) TiO2 nanoparticles. These particles have been tested for photoactivation-mediated cytotoxicity using near-visible light exposure. The reduction in TiO2 band gap energy with incremental levels of Fe loading maintained the nanoparticle crystalline structure in spite of homogeneous Fe distribution (demonstrated by XRD, HRTEM, SAED, EFTEM, and EELS). Photochemical studies showed that band gap energy was reciprocally tuned proportional to the Fe content. The photo-oxidation capability of Fe-doped TiO2 was found to increase during near-visible light exposure. Use of a macrophage cell line to evaluate cytotoxic and ROS production showed increased oxidant injury and cell death in parallel with a decrease in band gap energy. These findings demonstrate the importance of band gap energy in the phototoxic response of the cell to TiO2 nanoparticles and reflect the potential of this material to generate adverse effects in humans and the environment during high intensity light exposure. PMID:21678906

Tuning cationic composition of La:EuTiO{sub 3−δ} films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shkabko, Andrey, E-mail: shkabko@gmail.com; Empa, Solid State Chemistry and Catalysis, CH-8600 Dübendorf; Xu, Chencheng

2013-11-01

Eu{sub 1−x}La{sub x}TiO{sub 3−δ} (x = 0, 0.3, 0.5) films were deposited in a p(Ar(96%)/H{sub 2}(4%)) = 4 × 10{sup −4} mbar atmosphere on (LaAlO{sub 3}){sub 0.3}-(Sr{sub 2}AlTaO{sub 6}){sub 0.7} vicinal substrates (0.1°). Reflection high-energy electron diffraction oscillation characteristics of a layer-by-layer growth mode were observed for stoichiometric and Ti-rich films and the laser fluence suited to deposit stoichiometric films was identified to be 1.25 J/cm{sup 2} independent of the La content. The variety of resulting film compositions follows the general trend of Eu-enrichment for low laser and Ti-enrichment for high laser fluence. X-ray diffraction confirms that all the filmsmore » are compressively strained with a general trend of an increase of c-axis elongation for non-stoichiometric films. The surfaces of non-stoichiometric films have an increased roughness, the highest sheet resistances, exhibit the presence of islands, and are Eu{sup 3+} rich for films deposited at low laser fluence.« less

Preparation and photocatalytic performance of fibrous Tb3+-doped TiO2 using collagen fiber as template

NASA Astrophysics Data System (ADS)

Luo, Ting; Wan, Xiang-Jun; Jiang, Shang-Xuan; Zhang, Li-Yuan; Hong, Zheng-Qu; Liu, Jiao

2018-04-01

Fibrous Tb3+-doped TiO2 were prepared using collagen fiber as template. Morphology, crystalline structure, surface area, element content, chemical composition and elemental chemical status, microstructure and element distribution of the prepared samples were characterized by using scanning electron microscopy, X-ray diffraction, specific surface area analysis, inductively coupled plasma atomic emission spectrometer, X-ray photoelectron spectroscopy, transmission electron microscope and element mapping, respectively. The photocatalytic activities were evaluated by following degradation of methyl orange. The results showed that the fiber structure of collagen template was fully preserved when the calcination temperature was 500-800 °C. However, with the increase of calcination temperature, crystallinity and average particle size were increased, and the photocatalytic performance was decreased. For 2% Tb3+-TiO2 calcined at 500 °C, the degradation rate of methyl orange reached 93.87% after 6 h when a high-pressure mercury lamp (150 W) was used as the light source for photocatalytic degradation. Titanium tanning agent performance was excellent, the yield of TiO2 was high, and the fiber structure was presented when 0.2 mol/L citric acid/sodium citrate buffer solution was used.

A-site stoichiometry and piezoelectric response in thin film PbZr 1-xTi xO 3

DOE PAGES

Marincel, Dan; Jesse, Stephen; Belianinov, Alex; ...

2015-05-29

Lead zirconate titanate (PZT) films with Zr/Ti ratios of 52/48 and 30/70 annealed at varying partial pressures of PbO within the perovskite phase field exhibited permittivities of 1150 and 600, respectively, with loss tangents of 0.02. Many of the functional properties, including the permittivity, piezoelectricity as indicated via the Rayleigh coefficients, and the aging rates were found to be weakly dependent of the lead content in the single phase field. Minor polarization electric field hysteresis loops and piezoelectric coefficient e 31,f values after a hot poling process suggest that the point defect helps stabilize the aligned domain states. Measurements ofmore » the local nonlinear response show an increased low response cluster size with decreasing PbO content, indicating that PbO deficiency acts to reduce domain wall motion where it is already low« less

Crystallization studies and dielectric properties of (Ba0.7Sr0.3)TiO3 in bariumaluminosilicate glass

NASA Astrophysics Data System (ADS)

Divya, P. V.; Vignesh, G.; Kumar, V.

2007-12-01

Ferroelectric glass-ceramics with a basic composition (1 - y)(Ba0.70Sr0.30)TiO3 : y(BaO : Al2O3 : 2SiO2) have been synthesized by the sol-gel method. The major crystalline phase is the perovskite. The crystallization of the ferroelectric phase in the glass matrix have been studied using differential thermal analysis and x-ray diffraction and the kinetic parameters characterizing the crystallization have been determined using an Arrhenius model. Glass contents <= 5 mol% promoted liquid phase sintering, which reduced the sintering temperature to 1250 °C. The dielectric permittivity of the glass-ceramic samples decreased and the ferroelectric-paraelectric phase transition became more diffuse with increasing glass content. The dielectric connectivity of the ferroelectric phase in the composite have also been investigated and are reported.

Suppression of H-/O2- exchange by incorporated nitride anions in the perovskite lattice

NASA Astrophysics Data System (ADS)

Takeiri, Fumitaka; Yajima, Takeshi; Yamamoto, Takafumi; Kobayashi, Yoji; Matsui, Toshiaki; Hester, James; Kageyama, Hiroshi

2017-12-01

We investigate the low temperature anion exchange behavior of hydride and oxide in perovskite oxynitrides. CaH2 reduction of (Sr1-xLax)Ti(O3-xNx) (0

Facile synthesis of carbon-mediated porous nanocrystallite anatase TiO2 for improved sodium insertion capabilities as an anode for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Wu, Feng; Luo, Rui; Xie, Man; Li, Li; Zhang, Xiaoxiao; Zhao, Luzi; Zhou, Jiahui; Wang, KangKang; Chen, Renjie

2017-09-01

Porous carbon-mediated nanocrystallite anatase TiO2 composites are synthesized successfully via a simple dilatory hydrolysis-calcination method. The structural and morphological characterizations reveal that carbon-mediated TiO2 with a carbon content of 9.9 wt % (C2-TiO2) shows a combination of mesoporous and macroporous structures with a pore volume of 0.20 cm3 g-1 and surface area of 40.3 m2 g-1. Notably, C2-TiO2 delivered enhanced electrochemical performances of a high charge capacity of 259 mA h g-1 at 0.1 C and a high rate performance of 110 mA h g-1 after 150 cycles, even at 1 C. A significant decrease is also observed in the electrochemical impedance of the carbon-mediated samples, which explains superior electrochemical performance. Compared with the bare anatase TiO2 (B-TiO2), improved sodium storage capabilities of carbon-mediated samples are attributed to the participation of carbon to form a symbiotic structure with TiO2, which not only increases pore volume of the samples but serves as highly conductive network to provide a Na+ diffusion path during the insertion/de-insertion of sodium ions. All of these encouraging results suggest that carbon-mediated TiO2 has a great potential for improving sodium insertion capabilities with a facile and low-cost synthesis process.

The influence of the substrate on the adhesive strength of the micro-arc oxidation coating developed on TiNi shape memory alloy

NASA Astrophysics Data System (ADS)

Hsieh, Shy-Feng; Ou, Shih-Fu; Chou, Chia-Kai

2017-01-01

TiNi shape memory alloys (SMAs), used as long-term implant materials, have a disadvantage. Ni-ion release from the alloys may trigger allergies in the human body. Micro-arc oxidation has been utilized to modify the surface of the TiNi SMA for improving its corrosion resistance and biocompatibility. However, there are very few reports investigating the essential adhesive strength between the micro-arc oxidized film and TiNi SMA. Two primary goals were attained by this study. First, Ti50Ni48.5Mo1.5 SMA having a phase transformation temperature (Af) less than body temperature and good shape recovery were prepared. Next, the Ti50Ni50 and Ti50Ni48.5Mo1.5 SMA surfaces were modified by micro-arc oxidation in phosphoric acid by applying relatively low voltages to maintain the adhesive strength. The results indicated that the pore size, film thickness, and P content increased with applied voltage. The micro-arc oxidized film, comprising Ti oxides, Ni oxide, and phosphate compounds, exhibited a glassy amorphous structure. The outmost surface of the micro-arc oxidized film contained a large amount of P (>12 at%) but only a trace of Ni (<5 at%). The adhesive strengths of all the micro-arc oxidized films exceeded the requirements of ISO 13779. Furthermore, Mo addition into TiNi SMAs was found to be favorable for improving the adhesive strength of the micro-arc oxidized film.

Jointed toxicity of TiO2 NPs and Cd to rice seedlings: NPs alleviated Cd toxicity and Cd promoted NPs uptake.

PubMed

Ji, Ye; Zhou, Yun; Ma, Chuanxin; Feng, Yan; Hao, Yi; Rui, Yukui; Wu, Wenhao; Gui, Xin; Le, Van Nhan; Han, Yaning; Wang, Yingcai; Xing, Baoshan; Liu, Liming; Cao, Weidong

2017-01-01

Previous studies have reported that nanoparticles (NPs) and heavy metals are toxic to the environment. However, the jointed toxicity is not yet well understood. This study was aimed to investigate the combined toxicity of TiO 2 NPs and the heavy metal cadmium (Cd) to plants. Rice (Oryzasativa L.) was selected as the target plant. The rice seedlings were randomly separated into 12 groups and treated with CdCl 2 (0, 10 and 20 mg/L) and TiO 2 NPs (0, 10, 100 and 1000 mg/L). The plant height, biomass and root length indicated significant toxicity of Cd to the growth, but TiO 2 NPs exhibited the potential ability to alleviate the Cd toxicity. Transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS) confirmed the existence of TiO 2 NPs in plants. Elemental analysis of Ti and Cd suggested that the presences of Cd significantly decreased the Ti accumulation in the rice roots in the co-exposure treatments. Interestingly, TiO 2 NPs could lower the Cd uptake and distribution in rice roots and leaves. The results of antioxidant enzyme activity, lipid peroxide as well as phytohormones varied in the different treatments. Comparing with the Cd alone treatment, the net photosynthetic rate and chlorophyll content were significantly increased in the co-exposure treatments, suggesting that TiO 2 NPs could tremendously reduce the Cd toxicity. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

The Effect of Particles Shape and Size on Feedstock Flowibility and Chemical content of As-sintered NiTi Alloys

NASA Astrophysics Data System (ADS)

Kadir, R. A. Abdul; Razali, R.; Mohamad Nor, N. H.; Subuki, I.; Ismail, M. H.

2018-05-01

This paper presents a comparative study of two different titanium powders in fabrication of NiTi alloys by metal injection moulding (MIM) route. Two batches of powder mixture consisted of Ni-Ti and Ni-TiH2 with atomic ratio (at%) of 50-50 were prepared. TiH2 powder was used as a substitution for pure Ti powder owing to its relatively cheaper cost and has been claimed favourable in producing less impurity uptake in sintering process. The binder system used for both mixtures comprised of composite binder of palm stearin (PS) and polyethylene (PE) at weigth ratio (wt%) of 60-40. The flow behaviour of the mixtures was analysed using a capillary rheometer at different shear rates and temperatures. The results showed that owing to irregular shape of TiH2 compared to Ti powder, the viscosity of the feedstock was significantly higher, thus required greater temperature in order to improve the mouldability of the feedstock. Nevertheless, both feedstocks exhibited pseudoplastic, a shear thinning behavior with shear rate and temperature, desirable properties for injection moulding process. Samples prepared with Ni-Ti feedstock were sintered in a high vacuum furnace, while Ni-TiH2 feedstock was sintered in a tube furnace under a flowing of Argon gas. The results showed that the impurity contents (Carbon and Oxygen) for both feedstocks were almost comparable, suggesting NiTi alloy samples prepared with TiH2 powder is an attractive route for manufacturing of NiTi alloys.

Quantitative evaluation of the pulmonary microdistribution of TiO2 nanoparticles using X-ray fluorescence microscopy after intratracheal administration with a microsprayer in rats.

PubMed

Zhang, Guihua; Shinohara, Naohide; Kano, Hirokazu; Senoh, Hideki; Suzuki, Masaaki; Sasaki, Takeshi; Fukushima, Shoji; Gamo, Masashi

2015-06-01

The unevenness of pulmonary nanoparticle (NP) distribution, which hinders the establishment of an absolute dose-response relationship, has been described as one of the limitations of intratracheal administration techniques for toxicological assessment of inhaled NPs. Quantification of the NP microdistribution would facilitate the establishment of a concentration-response relationship in localized regions of the lung; however, such quantitative methods have not been reported. Here, we established a quantitative method for evaluating pulmonary TiO2 NP microdistribution in rats using X-ray fluorescence microscopy. Ti intensity in lung sections from rats intratracheally administered 10 mg kg(-1) TiO2 NPs with a microsprayer was measured using X-ray fluorescence with a 100 µm beam size. Ti reference samples were prepared by dropping different concentrations of Ti solutions on glass slide or lung sections of untreated rat. Ti intensity increased linearly with Ti content in the reference samples on both substrates. The detection limit of TiO2 was estimated to be 6.3 ng mm(-2) . The reproducibility was confirmed for measurements done in the short- (2 weeks) and long-term (6 months). The quantitative results of TiO2 NP microdistribution suggested that more TiO2 NPs were distributed in the right caudal and accessory lobes, which are located downstream of the administration direction of the NP suspension, and the lower portion of each lobe. The detection rates of TiO2 NPs were 16.6-25.0%, 5.19-15.6%, 28.6-39.2%, 21.4-38.7% and 10.6-23.2% for lung sections from the right cranial, middle, caudal, accessory and left lobes, respectively. Copyright © 2015 John Wiley & Sons, Ltd.

[Analysis of X-Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry of Pangxidong Composite Granitoid Pluton and Its Implications for Magmatic Differentiation].

PubMed

Zeng, Chang-yu; Ding, Ru-xin; Li, Hong-zhong; Zhou, Yong-zhang; Niu, Jia; Zhang, Jie-tang

2015-11-01

Pangxidong composite granitoid pluton located in the southwestern margin of Yunkai massif. The metamorphic grade of this pluton increases from outside to inside, that is, banded-augen granitic gneisses, gneissoid granites and granites distribute in order from edge to core. X-Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry are conducted to study the geochemical characteristics of the three types of rocks. The result shows that all the three types of rocks are peraluminous rocks and their contents of main elements and rare earth elements change gradually. From granitic gneisses to granites, the contents of Al₂O₃, CaO, MgO, TiO₂, total rare earth elements and light rare earth elements increase, but the contents of SiO₂ and heavy rare earth elements decrease. It is suggested that the phylogenetic relationship exists between granitic gneisses, gneissoid granites and granites during the multi-stage tectonic evolution process. Furthermore, the remelting of metamorphosed supracrustal rocks in Yunkai massif is probably an important cause of granitoid rocks forming. The evolutionary mechanism is probably that SiO₂ and heavy rare earth elements were melt out from the protolith and gradually enriched upward, but Al₂O₃, CaO, MgO, TiO₂ and light rare earth elements enriched downward.

Fast growth with crystal splitting of morphology-controllable Bi2S3 flowers on TiO2 nanotube arrays

NASA Astrophysics Data System (ADS)

Yang, L. X.; Ding, Y. B.; Luo, S. L.; Luo, Y.; Deng, F.; Li, Y.

2013-03-01

Bi2S3 crystals with flower-like morphologies are deposited on TiO2 nanotube arrays (NTs) by applying the cathodic pulse electrodeposition (PED) technique at 120 °C in 20 s. The highly oriented TiO2 NTs/Ti serving as substrate has high surface energy which is favorable for Gibbs free energy decreasing in nucleation process. Numerous boundaries between NTs are nucleation sites for atomic clusters, resulting in a fast nucleation velocity. Effective and fast heterogeneous nucleation initiates a thermodynamic control growth model and finally leads to the fast formation of highly crystallized Bi2S3 with a typical splitting property. Ethylene glycol (EG) was introduced into the electrolytes to inhibit the typical growth along the c axis ([0 0 1] plane) and facilitate the growth along the ab plane, producing Bi2S3 crystals with variable morphologies from sheaves to flowers by increasing EG contents.

Thallium Toxicity: The Problem; An Analytical Approach; An Antidotal Study

DTIC Science & Technology

1993-05-15

of DMPS to significantly decrease the TI content in 4 target organs suggests it would not be useful in the treatment of T1 poisoning. Accoion For B y...would not be useful in the treatment of Ti poisoning. TABLE OF CONTENTS PAGE ACKNOWLEDGEMENTS ...................................... vii INTRODUCTION...6 PRODUCTION AND USES .............................. 7 ABSORPTION, DISTRIBUTION, EXCRETION ................. 8 MOLECULAR BASIS OF

Microstructure characterization and phase transformation kinetic study of ball-milled m-ZrO 2-30 mol% a-TiO 2 mixture by Rietveld method

NASA Astrophysics Data System (ADS)

Pradhan, S. K.; Dutta, H.

2005-05-01

High-energy ball milling of monoclinic ZrO 2-30 mol% anatase TiO 2 mixture at different durations results in the formation of m-ZrO 2-a-TiO 2 solid solution from which the nucleation of nanocrystalline cubic (c) ZrO 2 polymorphic phase sets in. Post-annealing of 12 h ball-milled sample at different elevated temperatures for 1 h results in almost complete formation of c-ZrO 2 phase. Microstructure of the unmilled, all the ball milled and annealed samples has been characterized by Rietveld's X-ray powder structure refinement method. Particle size, rms lattice strain, change in lattice parameters and phase content of individual phases have been estimated from Rietveld analysis, and are utilized to interpret the results. In course of milling, (1 1 1) of cubic lattice became parallel to ( 1bar 1 1) plane of monoclinic lattice due to the orientation effect and cubic phase may have been formed on the (0 0 1) of the m-ZrO 2-a-TiO 2 solid solution lattice. A comparative study of microstructure and phase transformation kinetics of ZrO 2-10, 20 and 30 mol% a-TiO 2 ball-milled and post-annealed samples reveals that rate of phase transformation m→c-ZrO 2 increases with increasing a-TiO 2 concentration and ∼30 mol% of nanocrystalline c-ZrO 2 phase can be obtained within 4 h of milling time in the presence of 30 mol% of a-TiO 2. The post-annealing treatment at 773, 873 and 973 K for 1 h duration each reveals that rate of c-ZrO 2 formation with increasing temperature is retarded with increasing a-TiO 2 concentration but the amount of c-ZrO 2 becomes almost equal (∼95 mol%) at 973 K. It suggests that almost fully stabilized nanocrystalline c-ZrO 2 can be formed by adding a tetravalent solute to m-ZrO 2.

Crystal zoning in a large-volume ignimbrite: constraints on the thermal history of a supervolcano magma system

NASA Astrophysics Data System (ADS)

Matthews, N. E.; Pyle, D. M.; Wilson, C. J.

2009-12-01

Chemical zoning of crystals provides an important archive of information that allows for the reconstruction of complex thermal histories and changes in melt composition of the magma reservoir during crystallization. Here we investigate cathodoluminescence (CL) and Ti zonation in quartz crystals extracted from pumices from the Whakamaru and Rangitaiki ignimbrite units (part of the large-volume Whakamaru Group Ignimbrites), New Zealand, to reconstruct the thermal history of the parent magma chamber(s). CL intensity images are taken as a proxy for Ti content and temperature variation during crystal growth, and direct estimates of temperature are made using the TitaniQ geothermometer (Wark & Watson 2006 Cont. Min. Pet.) based on Ti concentration in quartz. These results are reviewed in comparison with temperatures from Fe-Ti oxide geothermometry. Quartz zoning is also compared to zonation in feldspars (using BSE imaging) from the same pumice clasts in order to establish the degree to which different crystal species record similar or contrasting magmatic histories. Quartz crystals in Whakamaru pumice display a variety of CL zoning patterns and resorption boundaries. Overgrowths typically appear to truncate CL growth zoning within the crystal core, indicating periods of resorption and subsequent re-growth - consistent with magma recharge causing a marked change in conditions (temperature and/or volatile saturation) and multi-stage crystallisation. Crystals typically display a dark (lower Ti) resorbed core, with an abrupt change to a CL-bright rim, although irregular textures and complex variations between crystals are observed. Core-to-rim profiles of Ti concentration in analysed quartz crystals show Ti variations within the range 50-225 ppm, corresponding to crystallisation temperatures of 733-935°C (assuming TiO2 activity in the melt of 0.6), with the lowest values recorded in the crystal core, increasing in a step-wise pattern towards the rim. These values are consistent with Fe-Ti oxide temperature data for the same pumice clasts which provide a temperature range of 660-933°C. It is inferred that the major steps in Ti content (and thus CL brightness) represent short-term temperature fluctuations due to magma chamber recharge and rejuvenation of a crystal mush, while rim temperatures are likely to record the magma temperature at the time of eruption.

Effect of process control agent on the porous structure and mechanical properties of a biomedical Ti-Sn-Nb alloy produced by powder metallurgy.

PubMed

Nouri, A; Hodgson, P D; Wen, C E

2010-04-01

The influence of different amounts and types of process control agent (PCA), i.e., stearic acid and ethylene bis-stearamide, on the porous structure and mechanical properties of a biomedical Ti-16Sn-4Nb (wt.%) alloy was investigated. Alloy synthesis was performed on elemental metal powders using high-energy ball milling for 5h. Results indicated that varying the PCA content during ball milling led to a drastic change in morphology and particle-size distribution of the ball-milled powders. Porous titanium alloy samples sintered from the powders ball milled with the addition of various amounts of PCA also revealed different pore morphology and porosity. The Vickers hardness of the sintered titanium alloy samples exhibited a considerable increase with increasing PCA content. Moreover, the addition of larger amounts of PCA in the powder mixture resulted in a significant increase in the elastic modulus and peak stress for the sintered porous titanium alloy samples under compression. It should also be mentioned that the addition of PCA introduced contamination (mainly carbon and oxygen) into the sintered porous product. Crown Copyright 2009. Published by Elsevier Ltd. All rights reserved.

Effects of Oxygen Content on Tensile and Fatigue Performance of Ti-6Al-4 V Manufactured by Selective Laser Melting

NASA Astrophysics Data System (ADS)

Quintana, Oscar A.; Tong, Weidong

2017-12-01

We investigated the selective laser melting (SLM) process for development of Ti-6Al-4 V solid material with oxygen content corresponding to the extra low interstitial (ELI) and non-ELI conditions. The microstructure, chemistry, and tensile properties of samples in as-built and hot isostatically pressed (HIPed) condition were evaluated for both material types, while fatigue performance was evaluated by rotating bending fatigue tests on both smooth and notched SLM ELI and non-ELI Ti-6Al-4 V samples in HIPed condition.

Titanium dioxide in pyroclastic layers from volcanoes in the cascade range

USGS Publications Warehouse

Czamanske, G.K.; Porter, S.C.

1965-01-01

Rapid determinations of titanium dioxide have been made by x-ray emission techniques to evaluate the potentiality of using the TiO2 content of samples for checking field correlations and assisting in identification of pyroclastic units from Cascade volcanoes. Preliminary data suggest that the two most wide-spread units have characteristic ranges of TiO2 content and that other, less extensive layers have ranges which, though characteristic, often overlap the ranges of the more widespread layers. Relative to fresh samples, weathered samples from B and C soil horizons are enriched in TiO 2.

Effects of cation contaminants in conductive TiO2 ceramics

NASA Astrophysics Data System (ADS)

Yan, M. F.; Rhodes, W. W.

1982-12-01

Ten cation contaminants, namely Al, Ga, Co, Fe, Mg, Zn, Zr, Ca, Sr, and Ba were investigated for their effects on the electrical properties, microstructures, and discoloration of conductive TiO2 ceramics. It was found that Al, Ga, Co, Fe, and Mg cause discoloration and increase the electrical resistivity by a factor of 104 to 106 in Nb-doped TiO2 ceramics. The other dopants do not introduce such changes in TiO2. The electrical properties, microstructures, and discoloration were measured in specimens of AlxNb0.007Ti0.993-xO2 with 0≤x≤0.01. When the Al content exceeds a critical value, ranging from 0.48% at 1400 °C to 0.25% at 1200 °C, the electrical resistivities and grain size increase rapidly, and the specimen is discolored from the original black to an ivory white color. Color boundary migration induced by Al diffusion in Nb-doped TiO2 was quantitatively measured. From the kinetics of the boundary migration, the Al diffusivity (D) was calculated to be D=2.67 exp(-53.3 kcal/mole/RT) cm2/s in the temperature range of 1200 to 1400 °C. The rapid diffusion of the small cations, namely Al, Ga, Co, Fe, and Mg, results from an interstitial diffusion mechanism. However, other cations, having a radius larger than the interstitial channel (˜0.77 Å radius), cannot diffuse by this mechanism. Defect reactions are proposed to explain the increase in the electrical resistivity and microstructural changes due to Al diffusion. These defect reactions also show that the problem of acceptor contamination cannot be avoided by adding an excess quantity of donor dopant if the solubility of the donor is much less than that of the acceptor contaminant.

Preparation of mesoporous titanium dioxide anode by a film- and pore-forming agent for the dye-sensitized solar cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Wenjing; Xiao, Yaoming, E-mail: ymxiao@sxu.edu.cn; Han, Gaoyi, E-mail: han_gaoyis@sxu.edu.cn

2016-04-15

Highlights: • PVP is used as a film- and pore-forming agent to prepare the mesoporous TiO{sub 2} anode. • The TiO{sub 2} anode supplies high surface area for the dye adsorption. • The DSSC efficiency is strongly dependent on the pore properties of the TiO{sub 2} anode. • The DSSC efficiency with the TiO{sub 2} anode prepared by 20 wt% PVP reaches 8.39%. - Abstract: A novel mean of generating mesoporous titanium dioxide (TiO{sub 2}) anodes by employing polyvinylpyrrolidone (PVP) as the film- and pore-forming agent are proposed for dye-sensitized solar cells (DSSCs). The influences on the morphology and photovoltaicmore » performances of the TiO{sub 2} anodes are investigated by adjusting the PVP content in synthesizing the mesoporous TiO{sub 2} anodes. The photovoltaic conversion efficiency of the DSSC is found to be strongly dependent on the pore properties of the TiO{sub 2} anode. After the sintering process, the removal of the PVP leaves porously interconnected channel structures inside the TiO{sub 2} anode, supplying enhanced specific surface area for the dye adsorption as well as the efficient electron transmission. As a result, the TiO{sub 2} anode prepared by 20 wt% PVP presents the highest performances, based on which the DSSC achieves the highest conversion efficiency of 8.39%, approximately increased by 56.53% than that of the DSSC fabricated without PVP (5.36%).« less

Microstructural characterization and mechanical property of active soldering anodized 6061 Al alloy using Sn-3.5Ag-xTi active solders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wei-Lin, E-mail: wangwl77@gmail.com; Tsai, Yi-Chia, E-mail: tij@itri.org.tw

2012-06-15

Active solders Sn-3.5Ag-xTi varied from x = 0 to 6 wt.% Ti addition were prepared by vacuum arc re-melting and the resultant phase formation and variation of microstructure with titanium concentration were analyzed using X-ray diffraction, optical microscopy and scanning electron microscopy. The Sn-3.5Ag-xTi active solders are used as metallic filler to join with anodized 6061 Al alloy for potential applications of providing a higher heat conduction path. Their joints and mechanical properties were characterized and evaluated in terms of titanium content. The mechanical property of joints was measured by shear testing. The joint strength was very dependent on themore » titanium content. Solder with a 0.5 wt.% Ti addition can successfully wet and bond to the anodized aluminum oxide layers of Al alloy and posses a shear strength of 16.28 {+-} 0.64 MPa. The maximum bonding strength reached 22.24 {+-} 0.70 MPa at a 3 wt.% Ti addition. Interfacial reaction phase and chemical composition were identified by a transmission electron microscope with energy dispersive spectrometer. Results showed that the Ti element reacts with anodized aluminum oxide to form Al{sub 3}Ti-rich and Al{sub 3}Ti phases at the joint interfaces. - Highlights: Black-Right-Pointing-Pointer Active solder joining of anodized Al alloy needs 0.5 wt.% Ti addition for Sn-3.5Ag. Black-Right-Pointing-Pointer The maximum bonding strength occurs at 3 wt.% Ti addition. Black-Right-Pointing-Pointer The Ti reacts with anodized Al oxide to form Al{sub 3}Ti-rich and Al{sub 3}Ti at joint interface.« less

Structure and electrical properties of <001> textured (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 lead-free piezoelectric ceramics

NASA Astrophysics Data System (ADS)

Ye, S. K.; Fuh, J. Y. H.; Lu, L.

2012-06-01

<001> textured (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCTZ) lead-free piezoelectric ceramics were prepared by templated-grain growth method using BaTiO3 as template. The degree of orientation and the microstructure of the ceramics with different amount of template were investigated. The electrical properties of the textured-ceramics in the optimized condition were dramatically enhanced compared with randomly-oriented BCTZ ceramics. The textured BCTZ ceramics showed high piezoelectric constants d33 = 470 pC/N and d31 = -170 pC/N, and high electromechanical coupling factors kp = 44% and k31 = 22%. In addition, the Curie point of the textured ceramics revealed an increase with the template content.

TiCN thin films grown by reactive crossed beam pulsed laser deposition

NASA Astrophysics Data System (ADS)

Escobar-Alarcón, L.; Camps, E.; Romero, S.; Muhl, S.; Camps, I.; Haro-Poniatowski, E.

2010-12-01

In this work, we used a crossed plasma configuration where the ablation of two different targets in a reactive atmosphere was performed to prepare nanocrystalline thin films of ternary compounds. In order to assess this alternative deposition configuration, titanium carbonitride (TiCN) thin films were deposited. Two crossed plasmas were produced by simultaneously ablating titanium and graphite targets in an Ar/N2 atmosphere. Films were deposited at room temperature onto Si (100) and AISI 4140 steel substrates whilst keeping the ablation conditions of the Ti target constant. By varying the laser fluence on the carbon target it was possible to study the effect of the carbon plasma on the characteristics of the deposited TiCN films. The structure and composition of the films were analyzed by X-ray Diffraction, Raman Spectroscopy and non-Rutherford Backscattering Spectroscopy. The hardness and elastic modulus of the films was also measured by nanoindentation. In general, the experimental results showed that the TiCN thin films were highly oriented in the (111) crystallographic direction with crystallite sizes as small as 6.0 nm. It was found that the hardness increased as the laser fluence was increased, reaching a maximum value of about 33 GPa and an elastic modulus of 244 GPa. With the proposed configuration, the carbon content could be easily varied from 42 to 5 at.% by changing the laser fluence on the carbon target.

Titanium-bearing phases in the Earth's mantle (evidence from experiments in the MgO-SiO2-TiO2 ±Al2O3 system at 10-24 GPa)

NASA Astrophysics Data System (ADS)

Sirotkina, Ekaterina; Bobrov, Andrey; Bindi, Luca; Irifune, Tetsuo

2017-04-01

Introduction Despite significant interest of experimentalists to the study of geophysically important phase equilibria in the Earth's mantle and a huge experimental database on a number of the model and multicomponent systems, incorporation of minor elements in mantle phases was mostly studied on a qualitative level. The influence of such elements on structural peculiarities of high-pressure phases is poorly investigated, although incorporation of even small portions of them may have a certain impact on the PT-parameters of phase transformations. Titanium is one of such elements with the low bulk concentrations in the Earth's mantle (0.2 wt % TiO2) [1]; however, Ti-rich lithologies may occur in the mantle as a result of oceanic crust subduction. Thus, the titanium content is 0.6 wt% in Global Oceanic Subducted Sediments (GLOSS) [2], and 1.5 wt% TiO2, in MORB [3]. In this regard, accumulation of titanium in the Earth's mantle is related to crust-mantle interaction during the subduction of crustal material at different depths of the mantle. Experimental methods At 10-24 GPa and 1600°C, we studied the full range of the starting materials in the MgSiO3 (En) - MgTiO3 (Gkl) system in increments of 10-20 mol% Gkl and 1-3 GPa, which allowed us to plot the phase PX diagram for the system MgSiO3-MgTiO3 and synthesize titanium-bearing phases with a wide compositional range. The experiments were performed using a 2000-t Kawai-type multi-anvil high-pressure apparatus at the Geodynamics Research Center, Ehime University (Japan). The quenched samples were examined by single-crystal X-ray diffractometer, and the composition of phases was analyzed using SEM-EDS. Results The main phases obtained in experiments were rutile, wadsleyite, MgSiO3-enstatite, MgTiO3-ilmenite, MgTiSi2O7 with the weberite structure type (Web), Mg(Si,Ti)O3 and MgSiO3 with perovskite-type structure. At a pressure of 13 GPa for Ti-poor bulk compositions, an association of En+Wad+Rt is replaced by the paragenesis of Web+Wad+Rt. With increasing Glk content in the starting composition, Gkl+Wad+Rt association is formed. At a pressure of >17 GPa, an association of two phases with Prv-type structure is stable within a narrow range of starting compositions. Addition of Al to the starting material allows us to simulate the composition of natural bridgmanites, since lower mantle bridgmanites are characterized by significant Al contents. In addition, this study shows that, in contrast to Al, the high contents of Ti can stabilize bridgmanite-like compounds at considerably lower pressure (18 GPa) in comparison with pure MgSiO3 bridgmanite. Small crystals of titanium-rich phases, including Ti-Al-Brd and Web were examined by single-crystal X-ray diffractometer, which allowed us to study the influence of Ti on crystallochemical peculiarities of the mantle phases and on the phase transformations. This study was supported by the Foundation of the President of the Russian Federation for Young Ph.D. (projects no. MK 1277.2017.5 to E.A. Sirotkina) and partly supported by the Russian Foundation for Basic Research (project nos. 17-55-50062 to E.A. Sirotkina and A.V.Bobrov) [1] Ringwood, A.E. The chemical composition and origin of the Earth. In: Advances in Earth science. Hurley, P.M. (Editors), M.I.T. Press, Cambridge. 1966. P. 287-356 [2] Plank, T., Langmuir, C.H., 1998. The chemical composition of subducting sediment and its consequences for the crust and mantle. Chemical Geology 145, 325-394. [3] Wilson, M. (1989) Igneous Petrogenesis—A global tectonic approach, 466 p. Kluwer, Dordrecht.

Silicon, iron and titanium doped calcium phosphate-based glass reinforced biodegradable polyester composites as bone analogous materials

NASA Astrophysics Data System (ADS)

Shah Mohammadi, Maziar

Bone defects resulting from disease or traumatic injury is a major health care problem worldwide. Tissue engineering offers an alternative approach to repair and regenerate bone through the use of a cell-scaffold construct. The scaffold should be biodegradable, biocompatible, porous with an open pore structure, and should be able to withstand the applied forces. Phosphate-based glasses (PGs) may be used as reinforcing agents in degradable composites since their degradation can be predicted and controlled through their chemistry. This doctoral dissertation describes the development and evaluation of PGs reinforced biodegradable polyesters for intended applications in bone augmentation and regeneration. This research was divided into three main objectives: 1) Investigating the composition dependent properties of novel PG formulations by doping a sodium-free calcium phosphate-based glass with SiO2, Fe2O3, and TiO2. Accordingly, (50P2 O5-40CaO- xSiO2-(10-x)Fe2O3, where x = 10, 5 and 0 mol.%) and (50P2O5-40CaO-xSiO 2-(10-x)TiO2 where x = 10, 7, 5, 3 and 0 mol.%) formulations were developed and characterised. SiO2 incorporation led to increased solubility, ion release, pH reduction, as well as hydrophilicity, surface energy, and surface polarity. In contrast, doping with Fe2O 3 or TiO2 resulted in more durable glasses, and improved cell attachment and viability. It was hypothesised that the presence of SiO 2 in the TiO2-doped formulations could up-regulate the ionic release from the PG leading to higher alkaline phosphatase activity of MC3T3-E1 cells. 2) Incorporating Si, Fe, and Ti doped PGs as fillers, either as particulates (PGPs) or fibres (PGFs), into biodegradable polyesters (polycaprolactone (PCL) and semi-crystalline and amorphous poly(lactic acid) (PLA and PDLLA)) with the aim of developing degradable bone analogous composites. It was found that PG composition and geometry dictated the weight loss, ionic release, and mechanical properties of the composites. It was also hypothesised that a potential reaction between Si and the ester bond led to the formation of carboxylate by-products resulting in a lower molecular weight polymer, thus affecting the mechanical properties of the composites. Cytocompatibility assessment with MC3T3-E1 pre-osteoblasts showed that these composites were cytocompatible, and cell alignment along the PGFs was observed possibly due to their favourable ionic release properties. 3) Investigating the solid-state foaming using carbon dioxide (CO 2) of PDLLA-PGP composites with up to 30 vol.% filler content. While PDLLA foams resulted in 92% porosity, the porosity of the composites ranged between 79 and 91% which decreased with PGP content. In addition, a reduction in pore size was observed with increasing PGP content; however, the pore size maintained its range of 200-500 μm in all composite foams, suitable for bone tissue engineering applications. The percentage of open pores increased significantly with PGP content (up to 78% at 30 vol.% PGP). Compressive strength and modulus of PDLLA-PGP foams showed up to approximately 3-fold increase at 30 vol.% PGP content compared to neat PDLLA foams.

Effects of alloy composition on cyclic flame hot-corrosion attack of cast nickel-base superalloys at 900 deg C

NASA Technical Reports Server (NTRS)

Deadmore, D. L.

1984-01-01

The effects of Cr, Al, Ti, Mo, Ta, Nb, and W content on the hot corrosion of nickel base alloys were investigated. The alloys were tested in a Mach 0.3 flame with 0.5 ppmw sodium at a temperature of 900 C. One nondestructive and three destructive tests were conducted. The best corrosion resistance was achieved when the Cr content was 12 wt %. However, some lower-Cr-content alloys ( 10 wt%) exhibited reasonable resistance provided that the Al content alloys ( 10 wt %) exhibited reasonable resistance provided that the Al content was 2.5 wt % and the Ti content was Aa wt %. The effect of W, Ta, Mo, and Nb contents on the hot-corrosion resistance varied depending on the Al and Ti contents. Several commercial alloy compositions were also tested and the corrosion attack was measured. Predicted attack was calculated for these alloys from derived regression equations and was in reasonable agreement with that experimentally measured. The regression equations were derived from measurements made on alloys in a one-quarter replicate of a 2(7) statistical design alloy composition experiment. These regression equations represent a simple linear model and are only a very preliminary analysis of the data needed to provide insights into the experimental method.

Effect of Cr Contents and Heat Treating on Reverted Austenite in Maraging Steel Weldments

NASA Astrophysics Data System (ADS)

Kim, S. W.; Lee, H. W.

2018-05-01

By conducting flux cored arc welding (FCAW) on maraging steels with Cr contents of 1.4 and 5.2 wt%, this study observed the effects of Cr content and heat treating on reverted austenite formation in welded maraging steel. Aging treatment was carried out at the temperatures of 450, 480 and 530 °C for 3 h in each condition. As the aging temperature increased, reverted austenite was formed along the interdendritic and intercellular grain boundaries, and the proportion of reverted austenite increased with increasing Cr addition. The aging process led to the segregation of Ti and Mo along the interdendritic and intercellular grain boundaries. Some of the welded specimens were subjected to solution heat treatment at 820 and 1250 °C for 1 h after welding, resulting in a decrease in reverted austenite fraction.

Effect of Cr Contents and Heat Treating on Reverted Austenite in Maraging Steel Weldments

NASA Astrophysics Data System (ADS)

Kim, S. W.; Lee, H. W.

2018-03-01

By conducting flux cored arc welding (FCAW) on maraging steels with Cr contents of 1.4 and 5.2 wt%, this study observed the effects of Cr content and heat treating on reverted austenite formation in welded maraging steel. Aging treatment was carried out at the temperatures of 450, 480 and 530 °C for 3 h in each condition. As the aging temperature increased, reverted austenite was formed along the interdendritic and intercellular grain boundaries, and the proportion of reverted austenite increased with increasing Cr addition. The aging process led to the segregation of Ti and Mo along the interdendritic and intercellular grain boundaries. Some of the welded specimens were subjected to solution heat treatment at 820 and 1250 °C for 1 h after welding, resulting in a decrease in reverted austenite fraction.

Effects of Alloying Elements on the Formation of Core-Shell-Structured Reinforcing Particles during Heating of Al–Ti Powder Compacts

PubMed Central

Chen, Tijun; Gao, Min; Tong, Yunqi

2018-01-01

To prepare core-shell-structured Ti@compound particle (Ti@compoundp) reinforced Al matrix composite via powder thixoforming, the effects of alloying elements, such as Si, Cu, Mg, and Zn, on the reaction between Ti powders and Al melt, and the microstructure of the resulting reinforcements were investigated during heating of powder compacts at 993 K (720 °C). Simultaneously, the situations of the reinforcing particles in the corresponding semisolid compacts were also studied. Both thermodynamic analysis and experiment results all indicate that Si participated in the reaction and promoted the formation of Al–Ti–Si ternary compounds, while Cu, Mg, and Zn did not take part in the reaction and facilitated Al3Ti phase to form to different degrees. The first-formed Al–Ti–Si ternary compound was τ1 phase, and then it gradually transformed into (Al,Si)3Ti phase. The proportion and existing time of τ1 phase all increased as the Si content increased. In contrast, Mg had the largest, Cu had the least, and Si and Zn had an equivalent middle effect on accelerating the reaction. The thicker the reaction shell was, the larger the stress generated in the shell was, and thus the looser the shell microstructure was. The stress generated in (Al,Si)3Ti phase was larger than that in τ1 phase, but smaller than that in Al3Ti phase. So, the shells in the Al–Ti–Si system were more compact than those in the other systems, and Si element was beneficial to obtain thick and compact compound shells. Most of the above results were consistent to those in the semisolid state ones except the product phase constituents in the Al–Ti–Mg system and the reaction rate in the Al–Ti–Zn system. More importantly, the desirable core-shell structured Ti@compoundp was only achieved in the semisolid Al–Ti–Si system. PMID:29342946

TiO2 nanoparticles in seawater: Aggregation and interactions with the green alga Dunaliella tertiolecta.

PubMed

Morelli, Elisabetta; Gabellieri, Edi; Bonomini, Alessandra; Tognotti, Danika; Grassi, Giacomo; Corsi, Ilaria

2018-02-01

Titanium dioxide nanoparticles (TiO 2 NPs) have been widely employed in industrial applications, thus rising concern about their impact in the aquatic environment. In this study we investigated the chemical behaviour of TiO 2 NPs in the culture medium and its effect on the green alga Dunaliella tertiolecta, in terms of growth inhibition, oxidative stress, ROS (Reactive Oxygen Species) accumulation and chlorophyll content. In addition, the influence of exopolymeric substances (EPS) excreted by the microalgae on the stability of NPs has been evaluated. The physicochemical characterization showed a high propensity of TiO 2 NPs to form micrometric-sized aggregates within 30min, large enough to partially settle to the bottom of the test vessel. Indeed, an increasing amount of TiO 2 particles settled out with time, but the presence of EPS seemed to mitigate this behaviour in the first 6h of exposure where the main effects in D. tertiolecta were observed. TiO 2 NPs did not inhibit the 72-h growth rate of D. tertiolecta, nor affected the cellular chlorophyll concentration in the range 0.01-10mgL -1 . The time-course of ROS production showed an initial transient increase of ROS in TiO 2 NP-exposed algae compared to the control, concomitant with an enhancement of catalase activity. Interestingly, intracellular ROS was a small fraction of total ROS, the highest amount being extracellular. The occurrence of cell-mediated chemical transformations of TiO 2 NPs in the external medium, related to the presence of EPS, has been evaluated. Our results showed that carbohydrates were the major component of EPS, whereas proteins of medium molecular weight (20-80kDa) were preferentially bound to TiO 2 NPs, likely influencing their biological fate. Copyright © 2017 Elsevier Inc. All rights reserved.

Evolution of soils on quaternary reef terraces of Barbados, West Indies

USGS Publications Warehouse

Muhs, D.R.

2001-01-01

Soils on uplifted Quaternary reef terraces of Barbados, ???125,000 to ???700,000 yr old, form a climo-chronosequence and show changes in physical, chemical, and mineralogical properties with terrace age. Parent materials are dust derived from the Sahara, volcanic ash from the Lesser Antilles island arc, and detrital carbonate from the underlying reef limestone. Although some terrace soils are probably eroded, soils or their remnants are redder and more clay-rich with increasing terrace age. Profile-average Al2O3 and Fe2O3 content increases with terrace age, which partially reflects the increasing clay content, but dithionite-extractable Fe also increases with terrace age. Profile-average K2O/TiO2, Na2O/TiO2, and P2O5/TiO2 values decrease with terrace age, reflecting the depletion of primary minerals. Average SiO2/Al2O3 values also decrease with terrace age and reflect not only loss of primary minerals but also evolution of secondary clay minerals. Although they are not present in any of the parent materials, the youngest terrace soils are dominated by smectite and interstratified kaolinite-smectite, which gradually alter to relatively pure kaolinite over ???700,000 yr. Comparisons with other tropical islands, where precipitation is higher and rates of dust fall may be lower, show that Barbados soils are less weathered than soils of comparable age. It is concluded that many soil properties in tropical regions can be potentially useful relative-age indicators in Quaternary stratigraphic studies, even when soils are eroded or changes in soil morphology are not dramatic. ?? 2001 University of Washington.

Effect of Inner Electrode on Reliability of (Zn,Mg)TiO3-Based Multilayer Ceramic Capacitor

NASA Astrophysics Data System (ADS)

Lee, Wen‑His; Su, Chi‑Yi; Lee, Ying Chieh; Yang, Jackey; Yang, Tong; PinLin, Shih

2006-07-01

In this study, different proportions of silver-palladium alloy acting as the inner electrode were adopted to a (Zn,Mg)TiO3-based multilayer ceramic capacitor (MLCC) sintered at 925 °C for 2 h to evaluate the effect of the inner electrode on reliability. The main results show that the lifetime is inversely proportional to Ag content in the Pd/Ag inner electrode. Ag+1 diffusion into the (Zn,Mg)TiO3-based MLCC during cofiring at 925 °C for 2 h and Ag+1 migration at 140 °C against 200 V are both responsible for the short lifetime of the (Zn,Mg)TiO3-based MLCC, particularly the latter factor. A (Zn,Mg)TiO3-based MLCC with high Ag content in the inner electrode Ag/Pd=99/01 exhibits the shortest lifetime (13 h), and the effect of Ag+1 migration is markedly enhanced when the activation energy of the (Zn,Mg)TiO3 dielectric is greatly lowered due to the excessive formation of oxygen vacancies and the semiconducting Zn2TiO4 phase when Ag+ substitutes for Zn+2 during co-firing.

Studies of electrical conductivity and complex initial permeability of multiferroic xBa{sub 0.95}Sr{sub 0.05}TiO{sub 3}-(1-x)BiFe{sub 0.90}Gd{sub 0.10}O{sub 3} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miah, Mohammad J., E-mail: mmjulhash@yahoo.com; Department of Physics, Comilla University, Comilla; Khan, M. N. I.

Multiferroic xBa{sub 0.95}Sr{sub 0.05}TiO{sub 3}-(1-x)BiFe{sub 0.90}Gd{sub 0.10}O{sub 3} [xBST-(1-x)BFGO] (x = 0.00, 0.10 and 0.20) ceramics were prepared by the standard solid-state reaction technique. Crystal structure of the ceramics was determined by X-ray diffraction pattern. All the compositions exhibited rhombohedral crystal structure. The tolerance factor ‘t’ varied from 0.847 to 0.864. The AC conductivity spectrum followed the Jonscher’s power law. The Nyquist plots indicated that only grains have the contribution to the resistance in this material and the values of grain resistance (R{sub g}) increased with BST content. The real part of complex initial permeability decreased with the increase inmore » frequency and increased with increasing BST content. Magnetoelectric coefficient was determined for all compositions. The maximum value of magnetoelectric coefficient was found to be 1.467 mV.cm{sup −1}.Oe{sup −1} for x = 0.20.« less

Comparative in vitro study regarding the biocompatibility of titanium-base composites infiltrated with hydroxyapatite or silicatitanate

PubMed Central

2014-01-01

Background The development of novel biomaterials able to control cell activities and direct their fate is warranted for engineering functional bone tissues. Adding bioactive materials can improve new bone formation and better osseointegration. Three types of titanium (Ti) implants were tested for in vitro biocompatibility in this comparative study: Ti6Al7Nb implants with 25% total porosity used as controls, implants infiltrated using a sol–gel method with hydroxyapatite (Ti HA) and silicatitanate (Ti SiO2). The behavior of human osteoblasts was observed in terms of adhesion, cell growth and differentiation. Results The two coating methods have provided different morphological and chemical properties (SEM and EDX analysis). Cell attachment in the first hour was slower on the Ti HA scaffolds when compared to Ti SiO2 and porous uncoated Ti implants. The Alamar blue test and the assessment of total protein content uncovered a peak of metabolic activity at day 8–9 with an advantage for Ti SiO2 implants. Osteoblast differentiation and de novo mineralization, evaluated by osteopontin (OP) expression (ELISA and immnocytochemistry), alkaline phosphatase (ALP) activity, calcium deposition (alizarin red), collagen synthesis (SIRCOL test and immnocytochemical staining) and osteocalcin (OC) expression, highlighted the higher osteoconductive ability of Ti HA implants. Higher soluble collagen levels were found for cells cultured in simple osteogenic differentiation medium on control Ti and Ti SiO2 implants. Osteocalcin (OC), a marker of terminal osteoblastic differentiation, was most strongly expressed in osteoblasts cultivated on Ti SiO2 implants. Conclusions The behavior of osteoblasts depends on the type of implant and culture conditions. Ti SiO2 scaffolds sustain osteoblast adhesion and promote differentiation with increased collagen and non-collagenic proteins (OP and OC) production. Ti HA implants have a lower ability to induce cell adhesion and proliferation but an increased capacity to induce early mineralization. Addition of growth factors BMP-2 and TGFβ1 in differentiation medium did not improve the mineralization process. Both types of infiltrates have their advantages and limitations, which can be exploited depending on local conditions of bone lesions that have to be repaired. These limitations can also be offset through methods of functionalization with biomolecules involved in osteogenesis. PMID:24987458

Resistivity behavior of optimized PbTiO3 thin films prepared by spin coating method

NASA Astrophysics Data System (ADS)

Nurbaya, Z.; Wahid, M. H.; Rozana, M. D.; Alrokayan, S. A. H.; Khan, H. A.; Rusop, M.

2018-05-01

Th is study presents the resistivity behavior of PbTiO3 thin films which were prepared towards metal-insulator-metal capacitor device fabrication. The PbTiO3 thin films were prepared through sol-gel spin coating method that involved various deposition parameters that is (1) different molar concentration of PbTiO3 solutions, (2) various additional PbAc-content in PbTiO3 solutions, and (3) various annealing temperature on PbTiO3 thin films. Hence, an electrical measurement of current versus voltage was done to determine the resistivity behavior of PbTiO3 thin films.

Microstructures, mechanical behavior and strengthening mechanism of TiSiCN nanocomposite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wei; Liu, Ping; Xue, Zenghui

Recently, the arguments have existed in the strengthening mechanism and microstructural model of the nanocomposite film due to lack of the convincible experimental evidences. In this investigation, the quarternary TiSiCN nanocomposite films with the different C and Si contents are synthesized by the reactive-magnetron-sputtering technique. The TiSiCN film is characterized as the nanocomposite structure with the TiN nanocrystallites surrounded by the (Si 3N 4 + C + CN x) interface phase. When the C/Si content ratio is 2:2, the TiSiCN nanocomposite film is remarkably strengthened with the maximal hardness and elastic modulus of 46.1 GPa and 425 GPa, respectively. Meanwhile,more » the (Si 3N 4 + C + CN x) interfaces exhibit as a crystallized form, which can coordinate the growth misorientations and maintain the coherently epitaxial growth between the TiN nanocrystallites and interfaces. Through the high-resolution transmission electron microscopy (HRTEM) observations, this investigation firstly provides the direct experimental evidence for the crystallized feature of the interfaces when the TiSiCN nanocomposite film is strengthened, suggesting that the strengthening effect of the TiSiCN nanocomposite film can be attributed to the coherent-interface strengthening mechanism, which is expressed as the “nc-TiN/c-Si 3N 4/c-C/c-CN x” model.« less