Sample records for v-5cr-5ti heat bl63

  1. Permeation of deuterium implanted into V-15Cr-5Ti

    NASA Astrophysics Data System (ADS)

    Anderl, R. A.; Longhurst, G. R.; Struttmann, D. A.

    1987-02-01

    Permeation and reemission of deuterium for the vanadium alloy, V-15Cr-5Ti, was investigated using 3 keV, D 3+ ion beams from a small accelerator. The experiments consisted of measurement of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5 mm thick specimens heated to temperatures from 623 K to 823 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). For the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This is approximately 1000 times that seen in the austenitic stainless steel, PCA, and 200 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates that D = 1.4 × 10 -8 exp( -0.11 eV/ kT) (m 2/s), over the temperature range 723 K to 823 K.

  2. Tensile properties of V-Cr-Ti alloys after exposure in hydrogen-containing environments

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

    Natesan, K.; Soppet, W.K.

    A systematic study has been initiated at Argonne National Laboratory to evaluate the performance of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with hydrogen uptake in the samples and its influence on the microstructure and tensile properties of the alloys. At present, the principal effort has focused on the V-4Cr-4Ti alloy of heat identified as BL-71; however other alloys (V-5Cr-5Ti alloy of heats BL-63, and T87, plus V-4Cr-4Ti alloy from General Atomics [GA]) are also being evaluated. Other variables of interest are themore » effect of initial grain size on the tensile behavior of the alloys. Experiments conducted on specimens of various V-Cr-Ti alloys exposed to pH{sub 2} levels of 0.01 and 3 {times} 10{sup {minus}6} torr showed negligible effect of H{sub 2} on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed to 1.0 torr H{sub 2} pressure. Preliminary data from sequential exposures of the materials to low-pO{sub 2} and several low-pH{sub 2} environments did not reveal an adverse effect on the maximum engineering stress or on uniform and total elongation. Further, tests in H{sub 2} environments on specimens annealed at different temperatures showed that grain-size variation by a factor of {approx}2 had little or no effect on tensile properties.« less

  3. Subtask 12D3: Fracture properties of V-5Cr-5Ti Alloy

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

    Li, H.; Hamilton, M.L.; Jones, R.H.

    1995-03-01

    The purpose of this research is to investigate the effect of heat treatment on microstructure and fracture toughness of a V-5Cr-5Ti alloy in the range -50-100{degrees}C. Fracture toughness and impact tests were performed on a V-5Cr-5Ti alloy. Specimens annealed at 1125{degrees}C for 1 h and furnace cooled in a vacuum of 1.33 x 10{sup -5} Pa were brittle at room temperature (RT) and experienced a mixture of intergranular and cleavage fracture. Fracture toughness (J{sub IQ}) at RT was 52 kJ/m{sup 2} and the impact fracture energy (IFE) was 6 J. The IFE at -100{degrees}C was only 1 J. While specimensmore » exhibited high fracture toughness at 100{degrees}C (J{sub IQ} is 485 kj/m{sup 2}), fracture was a mixture of dimple and intergranular failure, with intergranular fracture making up 40% of the total fracture surface. The ductile to brittle transition temperature (DBTT) was estimated to be about 20{degrees}C. When some specimens were given an additional annealing at 890{degrees}C for 24 h, they became very ductile at RT and fractured by microvoid coalescence. The J{sub IQ} value increased from 52 kJ/m{sup 2} to {approximately}1100 kJ/m{sup 2}. The impact test failed to fracture specimens at RT due to a large amount of plastic deformation. 7 refs., 1 fig., 6 tabs.« less

  4. Relationships between microstructure and mechanical properties of Ti-5Al-5Mo-5V-3Cr-1Zr alloy

    NASA Astrophysics Data System (ADS)

    Li, Z. Y.; Wu, G. Q.; Huang, Z.

    2018-03-01

    Through a statistical, quantitative analysis on microstructure of Ti-5Al-5Mo-5V-3Cr-1Zr (Ti55531) alloy, the relationships between microstructure and mechanical properties and heat treatment temperatures were investigated. The results show that in Widmanstätten structure, the size of β grain is greatly increased with increasing annealing temperature. Static toughness is related to grain boundary alpha phase discontinuity, the tensile strength is related to acicular alpha phase interface length and acicular alpha phase proportion. In duplex microstructure, the tensile strength is related to the equiaxed alpha proportion. Elongation, static toughness and crack forming work are related to the equiaxed alpha proportion and negatively related to secondary phase proportion. The microstructure can be described quantitatively and the mechanical properties can be predicted by analysis of microstructure.

  5. Room-temperature fracture in V-(4-5)Cr-(4-5)Ti tensile specimens irradiated in Fusion-1 BOR-60 experiment

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

    Gazda, J.; Meshii, M.; Tsai, H.

    Specimens of V-(4-5)Cr-(4-5)Ti alloys were irradiated to {approx}18 dpa at 320 C in the Fusion-1 capsule inserted into the BOR-60 reactor. Tensile tests at 23 C indicated dramatic yield strength increase (>300%), lack of work hardening, and minimal (<1%) total elongations. SEM analysis of fracture and side surfaces were conducted to determine reduction in are and the mode of fracture. The reduction of area was negligible. All but one specimen failed by a combination of ductile shear deformation and cleavage crack growth. Transgranular cleavage cracks were initiated by stress concentrations at the tips of the shear bands. In side-view observations,more » evidence was found of slip bands typically associated with dislocation channeling. No differences due to pre-irradiation heat treatment and heat-to-heat composition variations were detected. The only deviation from this behavior was found in V-4Cr-4Ti-B alloy, which failed in the grip portion by complete cleavage cracking.« less

  6. Dynamic Shear Deformation and Failure of Ti-6Al-4V and Ti-5Al-5Mo-5V-1Cr-1Fe Alloys

    PubMed Central

    Chen, Pengwan

    2018-01-01

    To study the dynamic shear deformation and failure properties of Ti-6Al-4V (Ti-64) alloy and Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy, a series of forced shear tests on flat hat shaped (FHS) specimens for the two investigated materials was performed using a split Hopkinson pressure bar setup. The evolution of shear deformation was monitored by an ultra-high-speed camera (Kirana-05M). Localized shear band is induced in the two investigated materials under forced shear tests. Our results indicate that severe strain localization (adiabatic shear) is accompanied by a loss in the load carrying capacity, i.e., by a sudden drop in loading. Three distinct stages can be identified using a digital image correlation technique for accurate shear strain measurement. The microstructural analysis reveals that the dynamic failure mechanisms for Ti-64 and Ti-55511 alloys within the shear band are of a cohesive and adhesive nature, respectively. PMID:29303988

  7. Microstructural examination of V-(3-6%)Cr-(3-5%)Ti irradiated in the ATR-A1 experiment

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

    Gelles, D.S.

    Microstructural examination results are reported for four heats of V-(3-6%)Cr-(3-5%)Ti irradiated in the ATR-A1 experiment to {approximately}4 dpa at {approximately}200 and 300 C to provide an understanding of the microstructural evolution that may be associated with degradation of mechanical properties. Fine precipitates were observed in high density intermixed with small defect clusters for all conditions examined following the irradiation. The irradiation-induced precipitation does not appear to be affected by preirradiation heat treatment or composition.

  8. Tensile and impact properties of General Atomics 832864 heat of V-4Cr-4Ti alloy

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

    Tsai, H.; Nowicki, L.J.; Gazda, J.

    A 1300-kg heat of V-4Cr-4Ti alloy was procured by General Atomics (GA) for the DIII-D radiative divertor program. To determine the mechanical properties of this alloy, tensile and Charpy tests were conducted on specimens prepared from pieces of 4.8-mm-thick as-rolled plates, a major product form for the DIII-D application. The tensile tests were conducted at three temperatures, 26, 280 and 380 C, the last two being the anticipated peak temperatures during DIII-D boronization and postvent bake-out, respectively. Results from these tests show that the tensile and impact properties of the 832864 heat are comparable to those of the other smallermore » V-(4-5)Cr-(4-5)Ti alloy heats previously developed by the US Fusion Materials Program and that scale-up of vanadium alloy production can be successfully achieved as long as reasonable process control is implemented.« less

  9. Effect on fast neutron irradiation to 4 dpa at 400{degrees}C on the properties of V-(4-5)Cr-(4-5)Ti alloys

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

    Zinkle, S.J.; Alexander, D.J.; Robertson, J.P.

    1997-04-01

    Tensile, Charpy impact and electrical resistivity measurements have been performed at ORNL on V-4Cr-4Ti and V-5Cr-5Ti specimens that were prepared at ANL and irradiated in the lithium-bonded X530 experiment in the EBR-II fast reactor. All of the specimens were irradiated to a damage level of about 4 dpa at a temperature of {approximately}400{degrees}C. A significant amount of radiation hardening was evident in both the tensile and Charpy impact tests. The irradiated V-4Cr-4Ti yield strength measured at {approximately}390{degrees}C was >800 MPa, which is more than three times as high as the unirradiated value. The uniform elongations of the irradiated tensile specimensmore » were typically {approximately}1%, with corresponding total elongations of 4-6%. The ductile to brittle transition temperature of the irradiated specimens was less than the unirradiated resistivity, which suggests that hardening associated with interstitial solute pickup was minimal.« less

  10. Tensile properties of V-5Cr-5Ti alloy after exposure in air environment

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

    Natesan, K.; Soppet, W.K.

    1997-04-01

    Oxidation studies were conducted on V-5Cr-5Ti alloy specimens in an air environment to evaluate the oxygen uptake behavior of the alloy as a function of temperature and exposure time. The oxidation rates, calculated from parabolic kinetic measurements of thermogravimetric testing and confirmed by microscopic analysis of cross sections of exposed specimens, were 5, 17, and 27 {mu}m per year after exposure at 300, 400, and 500{degrees}C, respectively. Uniaxial tensile tests were conducted at room temperature and at 500{degrees}C on preoxidized specimens of the alloy to examine the effects of oxidation and oxygen migration on tensile strength and ductility. Correlations weremore » developed between tensile strength and ductility of the oxidized alloy and microstructural characteristics such as oxide thickness, depth of hardened layer, depth of intergranular fracture zone, and transverse crack length.« less

  11. Assessment of the radiation-induced loss of ductility in V-Cr-Ti alloys

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

    Rowcliffe, A.F.; Zinkle, S.J.

    1997-04-01

    Alloys based on the V-Cr-Ti system are attractive candidates for structural applications in fusion systems because of their low activation properties, high thermal stress factor (high thermal conductivity, moderate strength, and low coefficient of thermal expansion), and their good compatibility with liquid lithium. The U.S. program has defined a V-4Cr-4Ti (wt %) alloy as a leading candidate alloy based upon evidence from laboratory-scale (30 kg) heats covering the approximate composition range 0-8 wt % Ti and 5 to 15 wt % Cr. A review of the effects of neutron displacement damage, helium, and hydrogen generation on mechanical behavior, and ofmore » compatibility with lithium, water, and helium environments was presented at the ICFRM-5 conference at Clearwater in 1991. The results of subsequent optimization studies, focusing on the effects of fast reactor irradiation on tensile and impact properties of a range of alloys, were presented at the ICFRM-6 conference at Stresa in 1993. The primary conclusion of this work was that the V-4Cr-4Ti alloy composition possessed a near-optimal combination of physical and mechanical properties for fusion structural applications. Subsequently, a production-scale (500 kg) heat of V-4Cr-4Ti (Heat No. 832665) was procured from Teledyne Wah-Chang, together with several 15 kg heats of alloys with small variations in Cr and Ti. Further testing has been carried out on these alloys, including neutron irradiation experiments to study swelling and mechanical property changes. This paper discusses ductility measurements from some of these tests which are in disagreement with earlier work.« less

  12. Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

    NASA Astrophysics Data System (ADS)

    Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2016-05-01

    Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

  13. Ferrimagnetic and spin-glass transition in the Aurivillius compound SrBi{sub 5}Ti{sub 4}Cr{sub 0.5}Co{sub 0.5}O{sub 18}

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

    Yuan, B.; Yang, J., E-mail: jyang@issp.ac.cn; Zuo, X. Z.

    Single-phase polycrystalline SrBi{sub 5}Ti{sub 4}CrO{sub 18} and SrBi{sub 5}Ti{sub 4}Cr{sub 0.5}Co{sub 0.5}O{sub 18} were synthesized by a modified Pechini method. Both samples have an orthorhombic structure with the space group B2cb. The valence state of Cr is suggested to be +3 and the Co ions exist in the form of Co{sup 2+} and Co{sup 3+} based on the results of x-ray photoelectron spectroscopy. The sample SrBi{sub 5}Ti{sub 4}CrO{sub 18} exhibits the paramagnetic state, whereas SrBi{sub 5}Ti{sub 4}Cr{sub 0.5}Co{sub 0.5}O{sub 18} undergoes a ferrimagnetic transition at 89 K originating from the antiferromagnetic coupling of Cr-based and Co-based sublattices. In addition, SrBi{sub 5}Ti{submore » 4}Cr{sub 0.5}Co{sub 0.5}O{sub 18} shows a typical spin-glass behavior below 89 K with zν = 6.02 and τ{sub 0} = (1.75 ± 0.33) × 10{sup −14} s as evidenced by the results of the frequency dependence of ac susceptibility and magnetic relaxation measurements. In particular, both the dielectric constant and dielectric loss of SrBi{sub 5}Ti{sub 4}Cr{sub 0.5}Co{sub 0.5}O{sub 18} exhibit the characteristics of dielectric relaxation around 89 K with the activation energy of (0.14 ± 0.02) eV, which can be ascribed to the electron hopping of Co{sup 2+}-V{sub O}-Co{sup 3+} through the bridging oxygen vacancies.« less

  14. Ab-initio calculation of EuO doped with 5% of (Ti, V, Cr and Fe): GGA and SIC approximation

    NASA Astrophysics Data System (ADS)

    Rouchdi, M.; Salmani, E.; Bekkioui, N.; Ez-Zahraouy, H.; Hassanain, N.; Benyoussef, A.; Mzerd, A.

    2017-12-01

    In this research, a simple theoretical method is proposed to investigate the electronic, magnetic and optical properties of Europium oxide (EuO) doped with 5% of (Ti, V, Cr and Fe). For a basic understanding of these properties, we employed Density-Functional Theory (DFT) based calculations with the Korringa-Kohn-Rostoker code (KKR) combined with the Coherent Potential Approximation (CPA). Also we investigated the half-metallic ferromagnetic behavior of EuO doped with 5% of (Ti, V, Cr and Fe) within the self-interaction-corrected Generalized Gradient Approximation (GGA-SIC). Our calculated results revealed that the Eu0.95TM0.05O is ferromagnetic with a high transition temperature. Moreover, the optical absorption spectra revealed that the half metallicity has been also predicted.

  15. Microstructural examination of irradiated vanadium alloys

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

    Gelles, D.S.; Chung, H.M.

    1997-04-01

    Microstructural examination results are reported for a V-5Cr-5Ti unirradiated control specimens of heat BL-63 following annealing at 1050{degrees}C, and V-4Cr-4Ti heat BL-47 irradiated in three conditions from the DHCE experiment: at 425{degrees}C to 31 dpa and 0.39 appm He/dpa, at 600{degrees}C to 18 dpa and 0.54 appm He/dpa and at 600{degrees}C to 18 dpa and 4.17 appm He/dpa.

  16. 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.

  17. Subtask 12B1: Welding development for V-Cr-Ti alloys

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

    King, J.F.; Goodwin, G.M.; Grossbeck, M.L.

    1995-03-01

    Development of the metallurgical and technological basis for the welding of thick sections of V-Cr-Ti alloys. The weldability and weldment properties of the V-5Cr-5Ti alloy have been evaluated. Results for the Sigmajig test of the vanadium alloy were similar to the cracking resistance of stainless steels, and indicates hot-cracking is unlikely to be a problem. Subsize Charpy test results for GTA weld metal in the as-welded condition have shown a significant reduction in toughness compared to the base metal. The weld metal toughness properties were restored to approximately that of the base metal after exposure to a PWHT 950{degrees}C. Themore » subsize Charpy toughness results for the EB weld metal from this same heat of vanadium alloy has shown significant improvement in properties compared to the GTA weld metal and the base metal. Further testing and analysis will be conducted to more fully characterize the properties of weld metal for each welding process and develop a basic understanding of the cause of the toughness decrease in the GTA welds. 5 figs., 1 tab.« less

  18. Effect of Aging Treatment on the Formation of α Precipitates in β-Type Ti-6Mo-6V-5Cr-3Sn-2.5Zr Alloys

    NASA Astrophysics Data System (ADS)

    Choi, Gwanghyo; Lee, Kwangmin

    2018-05-01

    The microstructural evolution of a novel β-type Ti-6Mo-6V-5Cr-3Sn-2.5Zr (wt%) alloy subjected to different aging treatments was investigated. The normalized intensity of the α precipitates reached a peak value at 450 °C. A nanoscale orthorhombic phase was observed to coexist with α precipitates in the β matrix, which followed the Burgers orientation relation of <1120>α//<111>β and {0001}α//{110}β. Fine α precipitates were formed with metastable O and β' phases, and the β phase was spinodally decomposed to β and β' phases. The maximum hardness value of the specimen was obtained after aging at 450 °C. Compositional partitioning of Mo, V, and Cr elements occurred with the depletion of fine acicular α precipitates upon aging 450 °C.

  19. Effect of Aging Treatment on the Formation of α Precipitates in β-Type Ti-6Mo-6V-5Cr-3Sn-2.5Zr Alloys

    NASA Astrophysics Data System (ADS)

    Choi, Gwanghyo; Lee, Kwangmin

    2018-02-01

    The microstructural evolution of a novel β-type Ti-6Mo-6V-5Cr-3Sn-2.5Zr (wt%) alloy subjected to different aging treatments was investigated. The normalized intensity of the α precipitates reached a peak value at 450 °C. A nanoscale orthorhombic phase was observed to coexist with α precipitates in the β matrix, which followed the Burgers orientation relation of <1120 >α//<111>β and {0001}α//{110}β. Fine α precipitates were formed with metastable O and β' phases, and the β phase was spinodally decomposed to β and β' phases. The maximum hardness value of the specimen was obtained after aging at 450 °C. Compositional partitioning of Mo, V, and Cr elements occurred with the depletion of fine acicular α precipitates upon aging 450 °C.

  20. Analysis of Microstructure and Sliding Wear Behavior of Co1.5CrFeNi1.5Ti0.5 High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Lentzaris, K.; Poulia, A.; Georgatis, E.; Lekatou, A. G.; Karantzalis, A. E.

    2018-04-01

    Α Co1.5CrFeNi1.5Ti0.5 high-entropy alloy (HEA) of the well-known family of CoCrFeNiTi has been designed using empirical parameters. The aim of this design was the production of a HEA with fcc structure that gives ductile behavior and also high strength because of the solid solution effect. The VEC calculations (8.1) supported the fcc structure while the δ factor calculations (4.97) not being out of the limit values, advised a significant lattice distortion. From the other hand, the ΔΗ mix calculations (- 9.64 kJ/mol) gave strong indications that no intermetallic would be formed. In order to investigate its potential application, the Co1.5CrFeNi1.5Ti0.5 HEA was prepared by vacuum arc melting and a primary assessment of its surface degradation response was conducted by means of sliding wear testing using different counterbody systems for a total sliding distance of 1000 m. An effort to correlate the alloy's wear response with the microstructural characteristics was attempted. Finally, the wear behavior of the Co1.5CrFeNi1.5Ti0.5 HEA was compared with that of two commercially used wear-resistant alloys. The results obtained provided some first signs of the high-entropy alloys' better wear performance when tested under sliding conditions against a steel ball.

  1. Oxyvanite, V3O5, a new mineral species and the oxyvanite-berdesinskiite V2TiO5 series from metamorphic rocks of the Slyudyanka Complex, southern Baikal region

    NASA Astrophysics Data System (ADS)

    Reznitsky, L. Z.; Sklyarov, E. V.; Armbruster, T.; Ushchapovskaya, Z. F.; Galuskin, E. V.; Polekhovsky, Yu. S.; Barash, I. G.

    2010-12-01

    Oxyvanite has been identified as an accessory mineral in Cr-V-bearing quartz-diopside meta- morphic rocks of the Slyudyanka Complex in the southern Baikal region, Russia. The new mineral was named after constituents of its ideal formula (oxygen and vanadium). Quartz, Cr-V-bearing tremolite and micas, calcite, clinopyroxenes of the diopside-kosmochlor-natalyite series, Cr-bearing goldmanite, eskolaite-karelianite dravite-vanadiumdravite, V-bearing titanite, ilmenite, and rutile, berdesinskiite, schreyerite, plagioclase, scapolite, barite, zircon, and unnamed U-Ti-V-Cr phases are associated minerals. Oxyvanite occurs as anhedral grains up to 0.1-0.15 mm in size, without visible cleavage and parting. The new mineral is brittle, with conchoidal fracture. Observed by the naked eye, the mineral is black, with black streak and resinous luster. The microhardness (VHN) is 1064-1266 kg/mm2 (load 30 g), and the mean value is 1180 kg/mm2. The Mohs hardness is about 7.0-7.5. The calculated density is 4.66(2) g/cm3. The color of oxyvanite is pale cream in reflected light, without internal reflections. The measured reflectance in air is as follows (λ, nm- R, %): 440-17.8; 460-18; 480-18.2; 520-18.6; 520-18.6; 540-18.8; 560-18.9; 580-19; 600-19.1; 620-19.2; 640-19.3; 660-19.4; 680-19.5; 700-19.7. Oxyvanite is monoclinic, space group C2/ c; the unit-cell dimensions are a = 10.03(2), b = 5.050(1), c = 7.000(1) Å, β = 111.14(1)°, V = 330.76(5)Å3, Z = 4. The strongest reflections in the X-ray powder pattern [ d, Å, ( I in 5-number scale)( hkl)] are 3.28 (5) (20 bar 2 ); 2.88 (5) (11 bar 2 ); 2.65, (5) (310); 2.44 (5) (112); 1.717 (5) (42 bar 2 ); 1.633 (5) (31 bar 4 ); 1.446 (4) (33 bar 2 ); 1.379 (5) (422). The chemical composition (electron microprobe, average of six point analyses, wt %): 14.04 TiO2, 73.13 V2O3 (53.97 V2O3calc, 21.25 VO2calc), 10.76 Cr2O3, 0.04 Fe2O3, 0.01 Al2O3, 0.02 MgO, total is 100.03. The empirical formula is (V{1.70/3+} Cr0.30)2.0(V{0.59/4+} Ti0.41)1.0O

  2. Electron energy loss spectroscopy analysis of lithium deintercalated Li5/3-xTi7/3CrO7

    NASA Astrophysics Data System (ADS)

    Díaz-Carrasco, P.; Moreau, P.; Guyomard, D.; Kuhn, A.; García-Alvarado, F.

    2006-05-01

    Electron energy loss spectroscopy has been used to investigate the average oxidation state of Cr in both electrochemically and chemically delithiathed Li5/3-xTi7/3CrO7. The O K edge, Ti L2,3 and Cr L2,3 edge were monitored. Upon removal of Li ions, the oxygen K edge shows a continuous change while the Cr L edges remain almost unchanged. The Cr 2p multiplet was compared with reference samples (Cr2O3, CrO2 and K2Cr2O7) in order to assess on the sensitivity of the Cr L-edge to the oxidation state of chromium ion. The similarity between the Cr L spectra of Cr2O3 and CrO2 makes the valence analysis difficult in Li5/3-xTi7/3CrO7 but the presence of CrVI is excluded in oxidized samples. However, evolution of the low energy loss spectra observed in the 10 15 eV region confirms the modification of the electronic structure and partial oxidation of CrIII to CrIV.

  3. Magnetic and magnetoelectric properties of NdCrTiO5 revealed by systematically rare-earth doping

    NASA Astrophysics Data System (ADS)

    Li, Qing; Feng, Zhenjie; Cheng, Cheng; Wang, Bojie; Chu, Hao; Huang, Ping; Wang, Difei; Qian, Xiaolong; Yu, Chuan; Wang, Guohua; Deng, Dongmei; Jing, Chao; Cao, Shixun; Zhang, Jincang

    2018-01-01

    We have systematically synthesized polycrystalline samples of Nd0.9A0.1CrTiO5 (A = Pr, Nd, Gd, Dy, Er, Tm, and Yb), and have investigated their crystal structure, polarization and magnetic susceptibility. The polarization values of doped samples are suppressed comparing to pure NdCrTiO5 sample, which indicates that the polarization is highly dependence with the magnetic moments of doping ions. The TN of Cr-Cr in Nd0.9A0.1CrTiO5 are dominated by both the suppression effect caused by doped magnetic moment increment and the enhancement effect caused by c axis contracting. We conclude that the magnetic moments in the rare-earth Nd sites play an important role in the magnetoelectric effect in NdCrTiO5 family. The substitution effect discussion here can help us well understand the intrinsic mechanism and provide a possible guidance in exploring new magnetoelectric coupling systems.

  4. Electrode characteristics of nanocrystalline (Zr, Ti)(V, Cr, Ni) 2.41 compound

    NASA Astrophysics Data System (ADS)

    Majchrzycki, W.; Jurczyk, M.

    The electrochemical properties of nanocrystalline Zr 0.35Ti 0.65V 0.85Cr 0.26Ni 1.30 alloy, which has the hexagonal C14 type structure, have been investigated. This material has been prepared using mechanical alloying (MA) followed by annealing. The amorphous phase forms directly from the starting mixture of the elements, without other phase formation. Heating the MA samples at 1070 K for 0.5 h resulted in the creation of ordered alloy. This alloy was used as negative electrode for Ni-MH x battery. The electrochemical results show very little difference between the nanocrystalline and polycrystalline powders, as compared with the substantial difference between these and the amorphous powder. In the annealed nanocrystalline Zr 0.35Ti 0.65V 0.85Cr 0.26Ni 1.30 powders discharging capacities up to 150 mA h g -1 (at 160 mA g -1 discharging current) have been measured. The properties of nanocrystalline electrode were attributed to the structural characteristics of the compound caused by mechanical alloying.

  5. Electrical resistivity of V-Cr-Ti alloys

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

    Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S.

    1997-04-01

    Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

  6. Valence of Ti, V, and Cr in Apollo 14 aluminous basalts 14053 and 14072

    NASA Astrophysics Data System (ADS)

    Simon, Steven B.; Sutton, Stephen R.

    2017-09-01

    The valences of Ti, V, and Cr in olivine and pyroxene, important indicators of the fO2 of the source region of their host rocks, can be readily measured nondestructively by XANES (X-ray absorption near edge structure) spectroscopy, but little such work has been done on lunar rocks, and there is some uncertainty regarding the presence of Ti3+ in lunar silicates and the redox state of the lunar mantle. This is the first study involving direct XANES measurement of valences of multivalent cations in lunar rocks. Because high alumina activity facilitates substitution of Ti cations into octahedral rather than tetrahedral sites in pyroxene and Ti3+ only enters octahedral sites, two aluminous basalts from Apollo 14, 14053 and 14072, were studied. Most pyroxene contains little or no detectable Ti3+, but in both samples relatively early, magnesian pyroxene was found that has Ti valences that are not within error of 4; in 14053, this component has an average Ti valence of 3.81 ± 0.06 (i.e., Ti3+/[Ti3+ + Ti4+ = 0.19]). This pyroxene has relatively low atomic Ti/Al ratios (<0.4) due to crystallization before plagioclase, contrary to the long-held belief that lunar pyroxene with Ti/Al > 0.5 contains Ti3+ and pyroxene with lower ratios does not. Later pyroxene, with lower Mg/Fe and higher Ti/Al ratios, has higher proportions of Ti (all Ti4+) in tetrahedral sites. All pyroxene analyzed contains divalent Cr, ranging from 15 to 30% of the Cr present, and all but one analysis spot contains divalent V, accounting for 0 to 40% (typically 20-30%) of the V present. Three analyses of olivine in 14053 do not show any Ti3+, but Ti valences in 14072 olivine range from 4 down to 3.70 ± 0.10. In 14053 olivine, 50% of the Cr and 60% of the V are divalent. In 14072 olivine, the divalent percentages are 20% for Cr and 20-60% for V. These results indicate significant proportions of divalent Cr and V and limited amounts of trivalent Ti in the parental melts, especially when crystal

  7. The Relationships Between Microstructure, Tensile Properties and Fatigue Life in Ti-5Al-5V-5Mo-3Cr-0.4Fe (Ti-5553)

    NASA Astrophysics Data System (ADS)

    Foltz, John W., IV

    beta-titanium alloys are being increasingly used in airframes as a way to decrease the weight of the aircraft. As a result of this movement, Ti-5Al-5V-5Mo-3Cr-0.4Fe (Timetal 555), a high-strength beta titanium alloy, is being used on the current generation of landing gear. This alloy features good combinations of strength, ductility, toughness and fatigue life in alpha+beta processed conditions, but little is known about beta-processed conditions. Recent work by the Center for the Accelerated Maturation of Materials (CAMM) research group at The Ohio State University has improved the tensile property knowledge base for beta-processed conditions in this alloy, and this thesis augments the aforementioned development with description of how microstructure affects fatigue life. In this work, beta-processed microstructures have been produced in a Gleeble(TM) thermomechanical simulator and subsequently characterized with a combination of electron and optical microscopy techniques. Four-point bending fatigue tests have been carried out on the material to characterize fatigue life. All the microstructural conditions have been fatigue tested with the maximum test stress equal to 90% of the measured yield strength. The subsequent results from tensile tests, fatigue tests, and microstructural quantification have been analyzed using Bayesian neural networks in an attempt to predict fatigue life using microstructural and tensile inputs. Good correlation has been developed between lifetime predictions and experimental results using microstructure and tensile inputs. Trained Bayesian neural networks have also been used in a predictive fashion to explore functional dependencies between these inputs and fatigue life. In this work, one section discusses the thermal treatments that led to the observed microstructures, and the possible sequence of precipitation that led to these microstructures. The thesis then describes the implications of microstructure on fatigue life and

  8. 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.

  9. Microstructure and mechanical properties of a newly developed low Young's modulus Ti-15Zr-5Cr-2Al biomedical alloy.

    PubMed

    Wang, Pan; Wu, Lihong; Feng, Yan; Bai, Jiaming; Zhang, Baicheng; Song, Jie; Guan, Shaokang

    2017-03-01

    The Ti-15Zr-5Cr-2Al alloy has been developed and various heat treatments have been investigated to develop new biomedical materials. It is found that the heat treatment conditions strongly affect the phase constitutions and mechanical properties. The as-cast specimen is comprised of β phase and a small fraction of α phase, which is attributed to the suppression of ω phase caused by adding Al. A high yield strength of 1148±36MPa and moderate Young's modulus of 96±3GPa are obtained in the as-cast specimen. Besides the β phase and α phase, ω phase is also detected in the air cooled and liquid nitrogen quenched specimens, which increases the Young's modulus and lowers the ductility. In contrast, only β phase is detected after ice water quenching. The ice water quenched specimen exhibits a good combination of mechanical properties with a high microhardness of 302±10HV, a large plastic strain of 23±2%, a low Young's modulus of 58±4GPa, a moderate yield strength of 625±32MPa and a high compressive strength of 1880±59MPa. Moreover, the elastic energies of the ice water quenched specimen (3.22MJ/m 3 ) and as-cast specimen (6.86MJ/m 3 ) are higher than that of c.p. Ti (1.25MJ/m 3 ). These results demonstrate that as-cast and ice water quenched Ti-15Zr-5Cr-2Al alloys with a superior combination of mechanical properties are potential materials for biomedical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Magnetic properties of new antiferromagnetic heavy-fermion compounds, Ce3TiBi5 and CeTi3Bi4

    NASA Astrophysics Data System (ADS)

    Motoyama, Gaku; Sezaki, Masumi; Gouchi, Jun; Miyoshi, Kiyotaka; Nishigori, Shijo; Mutou, Tetsuya; Fujiwara, Kenji; Uwatoko, Yoshiya

    2018-05-01

    We have succeeded in growing single crystals of hexagonal P63 / mcm Ce3TiBi5 and orthorhombic Fmmm CeTi3Bi4 by the Bi self-flux method. Measurements of electrical resistivity, magnetic susceptibility, and specific heat have been made on Ce3TiBi5 and CeTi3Bi4. The results indicate that both Ce3TiBi5 and CeTi3Bi4 are new Ce compounds with an antiferromagnetic ordering temperature of 5.0 and 3.4 K, respectively.

  11. 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.

  12. Controllable two-scale network architecture and enhanced mechanical properties of (Ti5Si3+TiBw)/Ti6Al4V composites.

    PubMed

    Jiao, Y; Huang, L J; Duan, T B; Wei, S L; Kaveendran, B; Geng, L

    2016-09-13

    Novel Ti6Al4V alloy matrix composites with a controllable two-scale network architecture were successfully fabricated by reaction hot pressing (RHP). TiB whiskers (TiBw) were in-situ synthesized around the Ti6Al4V matrix particles, and formed the first-scale network structure (FSNS). Ti5Si3 needles (Ti5Si3) precipitated in the β phase around the equiaxed α phase, and formed the secondary-scale network structure (SSNS). This resulted in increased deformation compatibility accompanied with enhanced mechanical properties. Apart from the reinforcement distribution and the volume fraction, the ratio between Ti5Si3 and TiBw fraction were controlled. The prepared (Ti5Si3 + TiBw)/Ti6Al4V composites showed higher tensile strength and ductility than the composites with a one-scale microstructure, and superior wear resistance over the Ti6Al4V alloy under dry sliding wear conditions at room temperature.

  13. Controllable two-scale network architecture and enhanced mechanical properties of (Ti5Si3+TiBw)/Ti6Al4V composites

    PubMed Central

    Jiao, Y.; Huang, L. J.; Duan, T. B.; Wei, S. L.; Kaveendran, B.; Geng, L.

    2016-01-01

    Novel Ti6Al4V alloy matrix composites with a controllable two-scale network architecture were successfully fabricated by reaction hot pressing (RHP). TiB whiskers (TiBw) were in-situ synthesized around the Ti6Al4V matrix particles, and formed the first-scale network structure (FSNS). Ti5Si3 needles (Ti5Si3) precipitated in the β phase around the equiaxed α phase, and formed the secondary-scale network structure (SSNS). This resulted in increased deformation compatibility accompanied with enhanced mechanical properties. Apart from the reinforcement distribution and the volume fraction, the ratio between Ti5Si3 and TiBw fraction were controlled. The prepared (Ti5Si3 + TiBw)/Ti6Al4V composites showed higher tensile strength and ductility than the composites with a one-scale microstructure, and superior wear resistance over the Ti6Al4V alloy under dry sliding wear conditions at room temperature. PMID:27622992

  14. Electrochemical properties of thin films of V2O5 doped with TiO2

    NASA Astrophysics Data System (ADS)

    Moura, E. A.; Cholant, C. M.; Balboni, R. D. C.; Westphal, T. M.; Lemos, R. M. J.; Azevedo, C. F.; Gündel, A.; Flores, W. H.; Gomez, J. A.; Ely, F.; Pawlicka, A.; Avellaneda, C. O.

    2018-08-01

    The paper presents a systematic study of the electrochromic properties of thin films of V2O5:TiO2 for a possible utilization as counter-electrode in electrochromic devices. The V2O5:TiO2 thin films were prepared by the sol-gel process and deposited on a substrate of fluorine-tin oxide transparent electrode (FTO) using the dip coating technique and heat treatment at 350 °C for 30 min. The films were characterized by chronocoulometry, cyclic voltammetry (CV), UV-Vis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), profilometry, and X-ray diffraction (XRD). The best results were obtained for the film of V2O5 with 7.5 mol% of TiO2, which presented highest ion storage capacity of ∼106 mC cm-2 and redox reversibility of 1. The diffusion of the Li+ ions into the thin films was modeled by solving Fick equations with appropriate boundary conditions for a plane sheet geometry. Besides that, these films showed optical modulation of 35% at 633 nm after coloration and bleaching. The XRD patterns revealed that the films have an orthorhombic crystal structure; the AFM and the profilometry confirmed roughness and thickness of 16.76 and 617 nm, respectively.

  15. Impact of x-ray dose on the response of CR-39 to 1–5.5 MeV alphas

    DOE PAGES

    Rojas-Herrera, J.; Rinderknecht, H. G.; Zylstra, A. B.; ...

    2015-03-01

    The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray uences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-K α and K β x-rays. The CR-39 detectors were then exposed to 1-5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those notmore » exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.« less

  16. Robust Strategy for Crafting Li5Cr7Ti6O25@CeO2 Composites as High-Performance Anode Material for Lithium-Ion Battery.

    PubMed

    Mei, Jie; Yi, Ting-Feng; Li, Xin-Yuan; Zhu, Yan-Rong; Xie, Ying; Zhang, Chao-Feng

    2017-07-19

    A facile strategy was developed to prepare Li 5 Cr 7 Ti 6 O 25 @CeO 2 composites as a high-performance anode material. X-ray diffraction (XRD) and Rietveld refinement results show that the CeO 2 coating does not alter the structure of Li 5 Cr 7 Ti 6 O 25 but increases the lattice parameter. Scanning electron microscopy (SEM) indicates that all samples have similar morphologies with a homogeneous particle distribution in the range of 100-500 nm. Energy-dispersive spectroscopy (EDS) mapping and high-resolution transmission electron microscopy (HRTEM) prove that CeO 2 layer successfully formed a coating layer on a surface of Li 5 Cr 7 Ti 6 O 25 particles and supplied a good conductive connection between the Li 5 Cr 7 Ti 6 O 25 particles. The electrochemical characterization reveals that Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode shows the highest reversibility of the insertion and deinsertion behavior of Li ion, the smallest electrochemical polarization, the best lithium-ion mobility among all electrodes, and a better electrochemical activity than the pristine one. Therefore, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode indicates the highest delithiation and lithiation capacities at each rate. At 5 C charge-discharge rate, the pristine Li 5 Cr 7 Ti 6 O 25 only delivers an initial delithiation capacity of ∼94.7 mAh g -1 , and the delithiation capacity merely achieves 87.4 mAh g -1 even after 100 cycles. However, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) delivers an initial delithiation capacity of 107.5 mAh·g -1 , and the delithiation capacity also reaches 100.5 mAh g -1 even after 100 cycles. The cerium dioxide modification is a direct and efficient approach to improve the delithiation and lithiation capacities and cycle property of Li 5 Cr 7 Ti 6 O 25 at large current densities.

  17. On the interdiffusion in multilayered silicide coatings for the vanadium-based alloy V-4Cr-4Ti

    NASA Astrophysics Data System (ADS)

    Chaia, N.; Portebois, L.; Mathieu, S.; David, N.; Vilasi, M.

    2017-02-01

    To provide protection against corrosion at high temperatures, silicide diffusion coatings were developed for the V-4Cr-4Ti alloy, which can be used as the fuel cladding in next-generation sodium-cooled fast breeder reactors. The multilayered coatings were prepared by halide-activated pack cementation using MgF2 as the transport agent and pure silicon (high activity) as the master alloy. Coated pure vanadium and coated V-4Cr-4Ti alloy were studied and compared as substrates. In both cases, the growth of the silicide layers (V3Si, V5Si3, V6Si5 and VSi2) was controlled exclusively by solid-state diffusion, and the growth kinetics followed a parabolic law. Wagner's analysis was adopted to calculate the integrated diffusion coefficients for all silicides. The estimated values of the integrated diffusion coefficients range from approximately 10-9 to 10-13 cm2 s-1. Then, a diffusion-based numerical approach was used to evaluate the growth and consumption of the layers when the coated substrates were exposed at critical temperatures. The estimated lifetimes of the upper VSi2 layer were 400 h and 280 h for pure vanadium and the V-4Cr-4Ti alloy, respectively. The result from the numeric simulation was in good agreement with the layer thicknesses measured after aging the coated samples at 1150 °C under vacuum.

  18. Thermo-mechanical treatment of low-cost alloy Ti-4.5Al-6.9Cr-2.3Mn and microstructure and mechanical characteristics

    NASA Astrophysics Data System (ADS)

    Chen, Guangyao; Kang, Juyun; Wang, Shusen; Wang, Shihua; Lu, Xionggang; Li, Chonghe

    2018-04-01

    In this study, the thermo-mechanical treatment process for low-cost Ti-4.5Al-6.9Cr-2.3Mn alloy were designed on the basis of assessment of Ti-Al-Cr-Mn thermodynamic system. The microstructure and mechanical properties of Ti-4.5Al-6.9Cr-2.3Mn forging and sheet were investigated by using the OM, SEM and universal tensile testing machine. The results show that both the forging and sheet were consisted of α + β phase, which is consistent with the expectation, and no element Cr and Mn existed in the grain boundaries of the sheet after quenching, and the C14 laves phase was not detected. The average ultimate tensile strength (σ b), 0.2% proof strength (σ 0.2) and elongation (EI) of alloy sheet after quenching can reach 1059 MPa, 1051 MPa and 24.6 Pct., respectively. Moreover, the average ultimate tensile strength of Ti-4.5Al-6.9Cr-2.3Mn forgings can reach 1599 MPa and the average elongation can reach 11.2 Pct., and a more excellent property of Ti-4.5Al-6.9Cr-2.3Mn forging is achieved than that of TC4 forging. It provides a theoretical support for further developing this low-cost alloy.

  19. Synthesis and electrochemical characteristics of LiCr xNi 0.5- xMn 1.5O 4 spinel as 5 V cathode materials for lithium secondary batteries

    NASA Astrophysics Data System (ADS)

    Hong, Ki-Joo; Sun, Yang-Kook

    A series of electrochemical spinel compounds, LiCr xNi 0.5- xMn 1.5O 4 ( x=0, 0.1, 0.3), are synthesized by a sol-gel method and their electrochemical properties are characterized in the voltage range of 3.5-5.2 V. Electrochemical data for LiCr xNi 0.5- xMn 1.5O 4 electrodes show two reversible plateaus at 4.9 and 4.7 V. The 4.9 V plateau is related to the oxidation of chromium while the 4.7 V plateau is ascribed to the oxidation of nickel. The LiCr 0.1Ni 0.4Mn 1.5O 4 electrode delivers a high initial capacity of 152 mAh g -1 with excellent cycleability. The excellent capacity retention of the LiCr 0.1Ni 0.4Mn 1.5O 4 electrode is largely attributed to structural stabilization which results from co-doping (chromium and nickel) and increased theoretical capacity due to substitution of chromium.

  20. Electrical conductivity and rate-capability of Li 4Ti 5O 12 as a function of heat-treatment atmosphere

    NASA Astrophysics Data System (ADS)

    Wolfenstine, J.; Lee, U.; Allen, J. L.

    Recently there has considerable interest in Li 4Ti 5O 12 as a potential anode for use in Li-ion batteries [1-8]. It has many advantages compared to the currently used graphite. For example, it is a zero-strain lithium insertion host suggesting virtually unlimited cycle life. It features a flat, operating voltage of about 1.5 V versus lithium, above the reduction potential of common electrolyte solvents thus, it does not form a solid electrolyte interface based on solvent reduction which should be a favorable property for high rate and low temperature operation. This voltage also is sufficiently high such that the dangers of lithium plating that can occur at high rate and/or low temperature are removed. However, several disadvantages exist compared to graphite. These include low rate-capability as a result of its low electronic conductivity [6]. Consequently, there have been several studies which have focused on improving electronic conductivity with the intent of improving its rate-capability [4,6,8]. For example, recently Huang et al. [8] have shown that the formation of a Li 4Ti 5O 12/Cu xO composite anode that was formed by heat-treatment under a 3 vol.% H 2 in N 2 atmosphere at high rates (>2C) had a higher capacity over a similar powders heat-treated under air. For example, at 10C the capacity of the powders heated under the 3 vol.% H 2 in N 2 atmosphere was about 1.8 X that for the powders heated under air and was attributed to the higher electrical conductivity of the composite heated under the reducing atmosphere compared to under air. The electrical conductivity of the composite formed under the reducing atmosphere was about an order magnitude higher than that for the composite heated under air. Huang et al. [8] suggested that the improved electrical conductivity was a result of the reduction of some Ti 4+ to Ti 3+ in Li 4Ti 5O 12 and/or reduction of Cu 2+/Cu + in Cu xO to Cu metal under the reducing atmosphere. However, they did not separate these effects

  1. Performance of V-4Cr-4Ti material exposed to DIII-D tokamak environment

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

    Tsai, H.; Chung, H.M.; Smith, D.L.

    1997-04-01

    Test specimens made with the 832665 heat of V-4Cr-4Ti alloy were exposed in the DIII-D tokamak environment to support the installation of components made of a V-4Cr-4Ti alloy in the radiative divertor of the DIII-D. Some of the tests were conducted with the Divertor Materials Evaluation System (DiMES) to study the short-term effects of postvent bakeout, when concentrations of gaseous impurities in the DIII-D chamber are the highest. Other specimens were mounted next to the chamber wall behind the divertor baffle plate, to study the effects of longer-term exposures. By design, none of the specimens directly interacted with the plasma.more » Preliminary results from testing the exposed specimens indicate only minor degradation of mechanical properties. Additional testing and microstructural characterization are in progress.« less

  2. Correlation of microstructure and low cycle fatigue properties for 13.5Cr1.1W0.3Ti ODS steel

    NASA Astrophysics Data System (ADS)

    He, P.; Klimenkov, M.; Möslang, A.; Lindau, R.; Seifert, H. J.

    2014-12-01

    Reduced activation oxide dispersion strengthened (ODS) steels are prospective structural materials for the blanket system and first wall components in Tokamak-type fusion reactors. Under the pulsed operation, these components will be predominantly subjected to cyclic thermal-mechanical loading which leads to inevitable fatigue damage. In this work, strain controlled isothermal fatigue tests were conducted for 13.5Cr1.1W0.3Ti ODS steel at 550 °C. The total strain range varied from 0.54% to 0.9%. After thermomechanical processing, 13.5CrWTi-ODS steel exhibits a remarkable lifetime extension with a factor of 10-20 for strain ranges Δε ⩽ 0.7%. 13.5Cr ODS steel shows no cyclic softening at all during the whole testing process irrespective of the strain range. TEM observations reveal ultrastable grain structure and constant dislocation densities around 1014 m-2, independent of the number of cycles or the applied strain amplitude. The presence of the stabilized ultrafine Y-Ti-O dispersoids enhances the microstructural stability and therefore leads to outstanding fatigue resistance for 13.5Cr1.1W0.3Ti-ODS steel.

  3. Delicate Ag/V2O5/TiO2 ternary nanostructures as a high-performance photocatalyst

    NASA Astrophysics Data System (ADS)

    Zhu, Xiao-Dong; Zheng, Ya-Lun; Feng, Yu-Jie; Sun, Ke-Ning

    2018-02-01

    Here we report, for the first time, delicate ternary nanostructures consisting of TiO2 nanoplatelets co-doped with Ag and V2O5 nanoparticles. The relationship between the composition and the morphology is systematically studied. We find a remarkable synergistic effect among the three components, and the resulting delicate Ag/V2O5/TiO2 ternary nanostructures exhibit a superior photocatalytic performance over neat TiO2 nanoplatelets as well as Ag/TiO2 and V2O5/TiO2 binary nanostructures for the degradation of methyl orange. We believe our delicate Ag/V2O5/TiO2 ternary nanostructures may lay a basis for developing next-generating, high-performance composite photocatalysts.

  4. Improving the Mechanical Properties of the Fusion Zone in Electron-Beam Welded Ti-5Al-5Mo-5V-3Cr Alloys

    NASA Astrophysics Data System (ADS)

    Marvel, Christopher J.; Sabol, Joseph C.; Pasang, Timotius; Watanabe, Masashi; Misiolek, Wojciech Z.

    2017-04-01

    It is well-known that ω-phase precipitates embrittle Ti-5553 alloys and that ω-phase embrittlement can be overcome with appropriate heat treatments. However, the microstructural evolution of electron-beam welded Ti-5553 is not as understood as compared to the cast or wrought material. This study compared the microstructures of as-welded and post-weld heat-treated specimens by scanning and transmission electron microscopy, and similarly compared the localized mechanical behavior of the fusion zones with microhardness testing and digital image correlation coupled tensile testing. The primary observations were that the embrittling ω-phase precipitates formed upon cooling, and could not be fully solutionized in a single-step treatment of 1077 K (804 °C) for 1 hour. It was also discovered that nanoscale α-phase precipitates nucleated after the single-step treatment, although they were small in number and sparsely distributed. However, a two-step heat treatment of 1077 K (804 °C) for 1 hour and 873 K (600 °C) for 4 hours completely solutionized the ω-phase and produced a dense network of 2- μm-wide α-phase plates, which significantly improved the mechanical properties. Overall, this study has shown that post-weld heat treatments improve the strength and ductility of electron-beam welded Ti-5553 alloys by controlling ω- and α-phase evolution.

  5. Modeling and Finite Element Analysis for the Dynamic Recrystallization Behavior of Ti-5Al-5Mo-5V-3Cr-1Zr Near β Titanium Alloy During Hot Deformation

    NASA Astrophysics Data System (ADS)

    Lv, Ya-ping; Li, Shao-jun; Zhang, Xiao-yong; Li, Zhi-you; Zhou, Ke-chao

    2018-04-01

    Evolution for the dynamic recrystallization (DRX) volume fraction of Ti-5Al-5Mo-5V-3Cr-1Zr near β titanium alloy during hot deformation was characterized by using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. To determine the equation parameters, a series of thermal simulation experiments at the temperature of 1023-1098 K and strain rate of 0.001-1 s‒1 to the true strain of 0.7 were conducted to obtain the essential data about stress σ and strain ɛ. By further transforming the relationship of σ versus ɛ into the relationship of strain hardening rate dσ/dɛ versus σ, two characteristic strains at the beginning of DRX (critical strain ɛc) and at the peak stress (peak strain ɛp) were identified from the dσ/dɛ-σ curves. Sequentially, the parameters in the JMAK equation were determined from the linear fitting of the different relationships among critical strain ɛc, peak strain ɛp and deformation conditions (including temperature T, strain rate \\dot ɛ and strain ɛ). The as-obtained JMAK equation was expressed as XDRX=1-exp[-0.0053((ɛ-ɛc)/ɛc)2.1], where ɛc=0.6053ɛp and ɛp=0.0031 \\dot ɛ .0081exp(28,781/RT). Finally, the JMAK equation was implanted into finite element program to simulate the hot compression of thermal simulation experiments. The simulation predictions and experimental results about the DRX volume fraction distribution showed a good consistency.

  6. 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.

  7. Probing the magnetic ground state of single crystalline Ce3TiSb5

    NASA Astrophysics Data System (ADS)

    Matin, M.; Kulkarni, R.; Thamizhavel, A.; Dhar, S. K.; Provino, A.; Manfrinetti, P.

    2017-04-01

    Motivated by the report of superconductivity in R3TiSb5 (R  =  La and Ce) and possibly Nd3TiSb5 at  ∼4 K, we grew single crystals of La3TiSb5 and Ce3TiSb5 by the high-temperature solution method using Sn as a flux. While in both compounds we observed a superconducting transition at 3.7 K for resistivity and low-field magnetization, our data conclusively show that it arose from residual Sn flux present in the single crystals. In particular, the heat capacity data do not present any of the anomalies expected from a bulk superconducting transition. The anisotropic magnetic properties of Ce3TiSb5, crystallizing in a hexagonal P63/mcm structure, were studied in detail. We find that the Ce ions in Ce3TiSb5 form a Kondo lattice and exhibited antiferromagnetic ordering at 5.5 K with a reduced moment and a moderately normalized Sommerfeld coefficient of 598 mJ/mol K2. The characteristic single-ion Kondo energy scale was found to be  ∼8 K. The magnetization data were subjected to a crystal electric field (CEF) analysis. The experimentally observed Schottky peak in the 4f-electron heat capacity of Ce3TiSb5 was reproduced fairly well by the energy levels derived from the CEF analysis.

  8. Fracture characteristics, microstructure, and tissue reaction of Ti-5Al-2.5Fe for orthopedic surgery

    NASA Astrophysics Data System (ADS)

    Niinomi, Mitsuo; Kobayashi, Toshiro; Toriyama, Osamu; Kawakami, Noriaki; Ishida, Yoshihito; Matsuyama, Yukihiro

    1996-12-01

    The microstructure of Ti-5Al-2.5Fe, which is expected to be used widely as an implant material not only for artificial hip joints but also for instrumentations of scoliosis surgery, was variously changed by heat treatments. The effect of the microstructure on mechanical properties, fracture toughness, and rotating-bending fatigue strength in the air and simulated body environment, that is, Ringer’s solution, was then investigated. Furthermore, the effect of the living body environment on mechanical properties and fracture toughness in Ti-5Al-2.5Fe were investigated on the specimens implanted into rabbit for about 11 months. The data of Ti-5Al-2.5Fe were compared with those of Ti-6Al-4V ELI, which has been used as an implant material mainly for artificial hip joints, and SUS 316L, which has been used as an implant material for many parts, including the instrumentation of scoliosis surgery. The equiaxed α structure, which is formed by annealing at a temperature below β transus, gives the best balance of strength and ductility in Ti-5Al-2.5Fe. The coarse Widmanstätten α structure, which is formed by solutionizing over β transus followed by air cooling and aging, gives the greatest fracture toughness in Ti-5Al-2.5Fe. This trend is similar to that reported in Ti-6Al-4V ELI. The rotating-bending fatigue strength is the greatest in the equiaxed α structure, which is formed by solutionizing below β transus followed by air cooling and aging in Ti-5Al-2.5Fe. Ti-5Al-2.5Fe exhibits much greater rotating-bending fatigue strength compared with SUS 316L, and equivalent rotating-bending fatigue strength to that of Ti-6Al-4V ELI in both the air and simulated body environments. The rotating-bending fatigue strength of SUS 316L is degraded in the simulated body environment. The corrosion fatigue, therefore, occurs in SUS 316L in the simulated body environment. Fatigue strength of Ti-5Al-2.5Fe in the simulated body environment is degraded by lowering oxygen content in the

  9. Measurement of hydrogen solubility and desorption rate in V-4Cr-4Ti and liquid lithium-calcium alloys

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

    Park, J.H.; Erck, R.; Park, E.T.

    1997-04-01

    Hydrogen solubility in V-4Cr-4Ti and liquid lithium-calcium was measured at a hydrogen pressure of 9.09 x 10{sup {minus}4} torr at temperatures between 250 and 700{degrees}C. Hydrogen solubility in V-4Cr-4Ti and liquid lithium decreased with temperature. The measured desorption rate of hydrogen in V-4Cr-4Ti is a thermally activated process; the activation energy is 0.067 eV. Oxygen-charged V-4Cr-4Ti specimens were also investigated to determine the effect of oxygen impurity on hydrogen solubility and desorption in the alloy. Oxygen in V-4Cr-4Ti increases hydrogen solubility and desorption kinetics. To determine the effect of a calcium oxide insulator coating on V-4Cr-4Ti, hydrogen solubility in lithium-calciummore » alloys that contained 0-8.0 percent calcium was also measured. The distribution ratio R of hydrogen between liquid lithium or lithium-calcium and V-4Cr-4Ti increased as temperature decreased (R {approx} 10 and 100 at 700 and 250{degrees}C, respectively). However at <267{degrees}C, solubility data could not be obtained by this method because of the slow kinetics of hydrogen permeation through the vanadium alloy.« less

  10. TiC reinforced cast Cr steels

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

    Dogan, O.N.; Hawk, J.A.; Schrems, K.K.

    2006-06-01

    A new class of materials, namely TiC-reinforced cast chromium (Cr) steels, was developed for applications requiring high abrasion resistance and good fracture toughness. The research approach was to modify the carbide structure of commercial AISI 440C steel for better fracture resistance while maintaining the already high abrasion resistance. The new alloys contained 12Cr, 2.5–4.5Ti, and 1–1.5C (wt.%) and were melted in a vacuum induction furnace. Their microstructure was composed primarily of a martensitic matrix with a dispersion of TiC precipitates. Modification of TiC morphology was accomplished through changing the cooling rate during solidification. Wear rates of the TiC-reinforced Cr steelsmore » were comparable to that of AISI 440C steel, but the impact resistance was much improved.« less

  11. Corrosion of V?Ti?Cr alloys in liquid lithium: influence of alloy composition and concentration of nitrogen in lithium

    NASA Astrophysics Data System (ADS)

    Eliseeva, O. I.; Fedirko, V. N.; Chernov, V. M.; Zavialsky, L. P.

    2000-12-01

    The effect of V-(0-70)Ti-(0-30)Cr (at.%) compositions on their compatibility with nitrogen-containing lithium (0.0015-0.67 at.% N) at 7000°C under steady-state test conditions and long-term contact with lithium (up to 2000 h) has been studied. The conditions for formation and stable coexistence of nitride layers on the surface of various compositions under variable nitrogen concentration in lithium have been defined. The V-(8-10)Ti-(4-5)Cr compositions showed the best characteristics from the standpoint of corrosion resistance, nitride layer stability under conditions of variable nitrogen concentration in lithium, and the possibility of 'in situ' protective nitride layer formation.

  12. Tensile properties of V-Cr-Ti alloys after exposure in oxygen-containing environments

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

    Natesan, K.; Soppet, W.K.

    A systematic study was conducted to evaluate the oxidation kinetics of V-4Cr-4Ti (44 alloy) and V-5Cr-5Ti alloys (55 alloy) and to establish the role of oxygen ingress on the tensile behavior of the alloys at room temperature and at 500 C. The oxidation rate of the 44 alloy is slightly higher than that of the 55 alloy. The oxidation process followed parabolic kinetics. Maximum engineering stress for 55 alloy increased with an increase in oxidation time at 500 C. The maximum stress values for 55 alloy were higher at room temperature than ta 500 C for the same oxidation treatment.more » Maximum engineering stresses for 44 alloy were substantially lower than those for 55 alloy in the same oxidation {approx}500 h exposure in air at 500 C; the same values were 4.8 and 6.1%, respectively, at 500 C after {approx}2060 h oxidation in air at 500 C. Maximum engineering stress for 44 alloy at room temperature was 421.6--440.6 MPa after {approx}250 h exposure at 500 C in environments with a pO{sub 2} range of 1 {times} 10{sup {minus}6} to 760 torr. The corresponding uniform and total elongation values were 11--14.4% and 14.5--21.7%, respectively. Measurements of crack depths in various specimens showed that depth is independent of pO{sub 2} in the preexposure environment and was of 70--95 {micro}m after 250--275 h exposure at 500 C.« less

  13. Electrochemical properties of TiO2-V2O5 nanocomposites as a high performance supercapacitors electrode material

    NASA Astrophysics Data System (ADS)

    Ray, Apurba; Roy, Atanu; Sadhukhan, Priyabrata; Chowdhury, Sreya Roy; Maji, Prasenjit; Bhattachrya, Swapan Kumar; Das, Sachindranath

    2018-06-01

    The individual components being ample, inexpensive and non-toxic material, TiO2-V2O5 has drawn more attention compared to other metal oxides. The cost-effective, non-toxic TiO2-V2O5 nanocomposites with various molar ratios of Ti and V have been synthesized through wet chemical method. Microstructure studies have been performed using X-ray diffraction (XRD), FESEM, HRTTEM and other spectroscopic (XPS, FTIR) techniques. The synthesized TiO2-V2O5 nanocomposite with molar ratio 10:20 exhibits 3D, mesoporous interlinked tube-like structure with excellent electrochemical properties by delivering highest specific capacitance of 310 F g-1 at 2 mV s-1 scan rate compared to individual TiO2 and V2O5 material. Increase in vanadium ratio plays a leading role to the chemical properties. The synergistic effects between TiO2 and V2O5 have also been observed in this work. Due to the excellent electrochemical as well as other acceptable performance, the porous interconnected tube like nanocomposite can be used for energy storage application mainly for pseudocapacitor electrode material.

  14. Rechargeability of the ambient temperature cell Li/2Me-THF, LiAsF6/Cr0.5V0.5S2

    NASA Astrophysics Data System (ADS)

    Abraham, K. M.; Harris, P. B.; Natwig, D. L.

    1983-12-01

    Practical usefulness of Cr0.5V0.5S2 as a rechargeable positive electrode for ambient temperature Li cells has been assesed. The rate-capacity behavior or the Cr0.5V0.5S2 cathode has been evaluated as a function of carbon content, electrolyte, and temperature. Rechargeability of the disulfide has been investigated by extended cycling of Li cells utilizing 2Me-THF/LiAsF6. Cells with cathode capacities as large as 10 Ahr have been constructed and tested. Many cells have exceeded 200 deep discharge-charge cycles. A scheme of studies useful for assessing the practicality of potential solid cathodes for ambient temperature rechargeable Li cells is presented.

  15. Microstructure and properties of Fe-based composite coating by laser cladding Fe-Ti-V-Cr-C-CeO2 powder

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zou, Yong; Zou, Zengda; Wu, Dongting

    2015-01-01

    In situ TiC-VC reinforced Fe-based cladding layer was obtained on low carbon steel surface by laser cladding with Fe-Ti-V-Cr-C-CeO2 alloy powder. The microstructure, phases and properties of the cladding layer were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), potentio-dynamic polarization and electro-chemical impedance spectroscopy (EIS). Results showed Fe-Ti-V-Cr-C-CeO2 alloy powder formed a good cladding layer without defects such as cracks and pores. The phases of the cladding layer were α-Fe, γ-Fe, TiC, VC and TiVC2. The microstructures of the cladding layer matrix were lath martensite and retained austenite. The carbides were polygonal blocks with a size of 0.5-2 μm and distributed uniformly in the cladding layer. High resolution transmission electron microscopy showed the carbide was a complex matter composed of nano TiC, VC and TiVC2. The cladding layer with a hardness of 1030 HV0.2 possessed good wear and corrosion resistance, which was about 16.85 and 9.06 times than that of the substrate respectively.

  16. The nano-particle dispersion strengthening of V-4Cr-4Ti alloys for high temperature application in fusion reactors

    NASA Astrophysics Data System (ADS)

    Zheng, Pengfei; Chen, Jiming; Xu, Zengyu; Duan, Xuru

    2013-10-01

    V-4Cr-4Ti was identified as an attractive structural material for Li blanket in fusion reactors. However, both high temperature and irradiation induced degradation are great challenges for this material. It was thought that the nano-particles with high thermal stability can efficiently strengthen the alloy at elevated temperatures, and accommodate the irradiation induced defects at the boundaries. This study is a starting work aiming at improving the creep resistance and reducing the irradiation induced degradation for V-4Cr-4Ti alloy. Currently, we focus on the preparation of some comparative nano-particle dispersion strengthened V-4Cr-4Ti alloys. A mechanical alloying (MA) route is used to fabricate yttrium and carbides added V-4Cr-4Ti alloys. Nano-scale yttria, carbides and other possible particles have a combined dispersion-strengthening effect on the matrices of these MA-fabricated V-4Cr-4Ti alloys. High-temperature annealing is carried out to stabilize the optimized nano-particles. Mechanical properties are tested. Microstructures of the MA-fabricated V-4Cr-4Ti alloys with yttrium and carbide additions are characterized. Based on these results, the thermal stability of different nano-particle agents are classified. ITER related China domestic project 2011GB108007.

  17. Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

    NASA Astrophysics Data System (ADS)

    Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

    2014-10-01

    Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

  18. Comparative Planetary Mineralogy: Valence State Partitioning of Cr, Fe, Ti, and V Among Crystallographic Sites in Olivine, Pyroxene, and Spinel from Planetary Basalts

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Karner, J. M.; Shearer, C. K.

    2005-01-01

    We have considered the valence-state partitioning of Cr, Fe, Ti, and V over crystallographic sites in olivine, pyroxene, and spinel from planetary basalts. The sites that accommodate these cations are the M2 site (6-8 coordinated) and M1 site (6 coordinated) in pyroxene, the M2 site (6-8 coordinated) and M1 site (6 coordinated) in olivine, and the tetrahedral and octahedral sites in spinel. The samples we studied are basalts from Earth, Moon, and Mars, which have fO2 conditions that range from IW-2 (Moon) to IW+6 (Earth) with Mars somewhere between at IW to IW+2. In this range of fO2 the significant elemental valences are (from low to high fO2) Ti4+, V3+, Fe2+, Cr2+, Cr3+, V3+, V4+, and Fe3+. V2+ and Ti3+ play a minor role in the phases considered for the Moon, and are probably in very low concentrations. V5+ plays a minor role in these phases in terrestrial basalts because it is probably in lower abundance than V4+ and it has an ionic radii that is so small (0.054 nm, 6- coordinated,[1]) that it is almost at the lower limit for octahedral coordination. The role of Cr2+ in the Moon is significant, as Sutton et al. [2] found that lunar olivine contains mostly Cr2+ while coexisting pyroxene contains mostly Cr3+. Hanson one vacancy only accommodates one V4+. Thus more vacancies are required in V4+ substitutions into olivine. In the Moon V3+ is much more abundant than V4+ [7, 8]. Thus in lunar chromite V3+ follows Cr3+, whereas in Earth V4+ (which is much greater in abundance than V3+) follows Ti4+ (eg in ulv spinel). We could go on in this vein for some time but space limitations do not permit us to do so.

  19. Heat-to-Heat Variation in Creep Life and Fundamental Creep Rupture Strength of 18Cr-8Ni, 18Cr-12Ni-Mo, 18Cr-10Ni-Ti, and 18Cr-12Ni-Nb Stainless Steels

    NASA Astrophysics Data System (ADS)

    Abe, Fujio

    2016-09-01

    Metallurgical factors causing the heat-to-heat variation in time to rupture have been investigated for 300 series stainless steels for boiler and heat exchanger seamless tubes, 18Cr-8Ni (JIS SUS 304HTB), 18Cr-12Ni-Mo (JIS SUS 316HTB), 18Cr-10Ni-Ti (JIS SUS321 HTB), and 18Cr-12Ni-Nb (JIS SUS 347HTB), at 873 K to 1023 K (600 °C to 750 °C) using creep rupture data for nine heats of the respective steels in the NIMS Creep Data Sheets. The maximum time to rupture was 222,705.3 hours. The heat-to-heat variation in time to rupture of the 304HTB and 316HTB becomes more significant with longer test durations at times above ~10,000 hours at 973 K (700 °C) and reaches to about an order of magnitude difference between the strongest and weakest heats at 100,000 hours, whereas that of the 321HTB and 347HTB is very large of about an order of magnitude difference from a short time of ~100 hours to long times exceeding 100,000 hours at 873 K to 973 K (600 °C to 700 °C). The heat-to-heat variation in time to rupture is mainly explained by the effect of impurities: Al and Ti for the 304HTB and 316HTB, which reduces the concentration of dissolved nitrogen available for the creep strength by the formation of AlN and TiN during creep, and boron for the 347HTB, which enhances fine distributions of M23C6 carbides along grain boundaries. The heat-to-heat variation in time to rupture of the 321HTB is caused by the heat-to-heat variation in grain size, which is inversely proportional to the concentration of Ti. The fundamental creep rupture strength not influenced by impurities is estimated for the steels. The 100,000 hours-fundamental creep rupture strength of the 347HTB steel is lower than that of 304HTB and 316HTB at 873 K and 923 K (600 °C and 650 °C) because the slope of stress vs time to rupture curves is steeper in the 347HTB than in the 304HTB and 316HTB. The 100,000 hours-fundamental creep rupture strength of the 321HTB exhibits large variation depending on grain size.

  20. Evaluation of Titanium-5Al-5Mo-5V-3Cr (Ti-5553) Alloy against Fragment and Armor-Piercing Projectiles

    DTIC Science & Technology

    2009-09-01

    Alloy Ti-6Al-4V; ARL-MR- 486; U.S. Army Research Laboratory: Aberdeen Proving Ground, MD, July 2000. Donachie, M. J., Jr. Titanium: A Technical...Tests of Armor Materials. TOP-2-2-710 (AD A137873), Aberdeen Proving Ground, MD, 8 July 1993. Veeck, S.; Lee, D.; Boyer, R.; Briggs, R. The...195 BEAR HILL RD WALTHAM MA 02451 1 RMI TITANIUM CO W PALLANTE PO BOX 269 1000 WARREN AVE NILES OH 44446 2 SOUTHWEST RSRCH INST

  1. Microstructures and Continuous Cooling Transformation of CGHAZ in E36 Class V-N-Ti, V-Ti and Nb-Ti Shipbuilding Steels

    NASA Astrophysics Data System (ADS)

    Shi, Zhongran; Wang, Ruizhen; Wang, Qingfeng; Su, Hang; Chai, Feng; Yang, Caifu

    For the purpose of obtaining the optimal microstructures and mechanical properties of the CGHAZ under high input welding, continuous cooling transformation diagrams of the coarse grain heat-affected zone (CGHAZ) and the corresponding microstructures were investigated for a E36 class V-N-Ti, V-Ti, and Nb-Ti shipbuilding steels. The results indicated that the CGHAZ continuous transformation behaviors of Nb-Ti and V-Ti steel were similar, but the V-retard phenomenon was not as apparent as that of Nb. In addition, the cooling rate of ferrite transformation of V-Ti steel was higher than that of Nb-Ti steel. The nitrogen addition in the V-Ti steel enhanced the ferrite transformation, since that increasing the nitrogen could obtain fine (Ti, V)(C, N) particles and refine the original austenite size, which can promote the ferrite nucleation. The bainite transformation range of V-N-Ti steel was obviously lower than that of Nb-Ti, V-Ti steel at the t8/5≥100s.

  2. Electrosynthesis of Ti5Si3, Ti5Si3/TiC, and Ti5Si3/Ti3SiC2 from Ti-Bearing Blast Furnace Slag in Molten CaCl2

    NASA Astrophysics Data System (ADS)

    Li, Shangshu; Zou, Xingli; Zheng, Kai; Lu, Xionggang; Chen, Chaoyi; Li, Xin; Xu, Qian; Zhou, Zhongfu

    2018-04-01

    Ti5Si3, Ti5Si3/TiC, and Ti5Si3/Ti3SiC2 have been electrochemically synthesized from the Ti-bearing blast furnace slag/TiO2 and/or C mixture precursors at a cell voltage of 3.8 V and 1223 K to 1273 K (950 °C to 1000 °C) in molten CaCl2. The pressed porous mixture pellets were used as the cathode, and a solid oxide oxygen-ion-conducting membrane (SOM)-based anode was used as the anode. The phase composition and morphologies of the cathodic products were systematically characterized. The final products possess a porous nodular microstructure due to the interconnection of particles. The variations of impurity elements, i.e., Ca, Mg, and Al, have been analyzed, and the result shows that Ca and Mg can be almost completely removed; however, Al cannot be easily removed from the pellet due to the formation of Ti-Al alloys during the electroreduction process. The electroreduction process has also been investigated by the layer-depended phase composition analysis of the dipped/partially reduced pellets to understand the detailed reaction process. The results indicate that the electroreduction process of the Ti-bearing blast furnace slag/TiO2 and/or C mixture precursors can be typically divided into four periods, i.e., (i) the decomposition of initial Ca(Mg,Al)(Si,Al)2O6, (ii) the reduction of Ti/Si-containing intermediate phases, (iii) the removal of impurity elements, and (iv) the formation of Ti5Si3, TiC, and Ti3SiC2. It is suggested that the SOM-based anode process has great potential to be used for the direct and facile preparation of Ti alloys and composites from cheap Ti-containing ores.

  3. 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

  4. Two-Phase (TiAl+TiCrAl) Coating Alloys for Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)

    1998-01-01

    A coating for protecting titanium aluminide alloys, including the TiAl gamma + Ti3Al (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

  5. Reactions of hydrogen with V-Cr-Ti alloys

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

    DiStefano, J.R.; DeVan, J.H.; Chitwood, L.D.

    In the absence of increases in oxygen concentration, additions of up to 400 ppm hydrogen to V-4 Cr-4 Ti did not result in significant embrittlement as determined by room temperature tensile tests. However, when hydrogen approached 700 ppm after exposure at 325 C, rapid embrittlement occurred. In this latter case, hydride formation is the presumed embrittlement cause. When oxygen was added during or prior to hydrogen exposure, synergistic effects led to significant embrittlement by 100 ppm hydrogen.

  6. Formation of unusual Cr5+ charge state in CaCr0.5Fe0.5O3 perovskite

    NASA Astrophysics Data System (ADS)

    Dai, Jian-Hong; Zhao, Qing; Sun, Qian; Zhang, Shuo; Wang, Xiao; Shen, Xu-Dong; Liu, Zhe-Hong; Shen, Xi; Yu, Ri-Cheng; Chan, Ting-Shan; Li, Lun-Xiong; Zhou, Guang-Hui; Yang, Yi-feng; Jin, Chang-Qing; Long, You-Wen

    2018-03-01

    A new oxide CaCr0.5Fe0.5O3 was prepared under high pressure and temperature conditions. It crystallizes in a B-site disordered Pbnm perovskite structure. The charge combination is determined to be Cr5+/Fe3+ with the presence of unusual Cr5+ state in octahedral coordination, although Cr4+ and Fe4+ occur in the related perovskites CaCrO3 and CaFeO3. The randomly distributed Cr5+ and Fe3+ spins lead to short-range ferromagnetic coupling, whereas an antiferromagnetic phase transition takes place near 50 K due to the Fe3+–O–Fe3+ interaction. In spite of the B-site Cr5+/Fe3+ disorder, the compound exhibits electrical insulating behavior. First-principles calculations further demonstrate the formation of {CaCr}}0.55+{Fe}}0.53+{{{O}}}3 charge combination, and the electron correlation effect of Fe3+ plays an important role for the insulting ground state. CaCr0.5Fe0.5O3 provides the first Cr5+ perovskite system with octahedral coordination, opening a new avenue to explore novel transition-metal oxides with exotic charge states. Project supported by the National Natural Science Foundation of China (Grant Nos. 11574378, 51772324, and 61404052),the National Basic Research Program of China (Grant No. 2014CB921500), and the Chinese Academy of Sciences (Grant Nos. YZ201555, QYZDB-SSW-SLH013, GJHZ1773, and XDB07030300).

  7. 25 CFR 63.5-63.9 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false [Reserved] 63.5-63.9 Section 63.5-63.9 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR TRIBAL GOVERNMENT INDIAN CHILD PROTECTION AND FAMILY VIOLENCE PREVENTION Purpose, Policy, and Definitions §§ 63.5-63.9 [Reserved] ...

  8. Yttria catalyzed microstructural modifications in oxide dispersion strengthened V-4Cr-4Ti alloys synthesized by field assisted sintering technique

    NASA Astrophysics Data System (ADS)

    Krishnan, Vinoadh Kumar; Sinnaeruvadi, Kumaran; Verma, Shailendra Kumar; Dash, Biswaranjan; Agrawal, Priyanka; Subramanian, Karthikeyan

    2017-08-01

    The present work deals with synthesis, characterisation and elevated temperature mechanical property evaluation of V-4Cr-4Ti and oxide (yttria = 0.3, 0.6 and 0.9 at%) dispersion strengthened V-4Cr-4Ti alloy processed by mechanical alloying and field-assisted sintering, under optimal conditions. Microstructural parameters of both powder and sintered samples were deduced by X-ray diffraction (XRD) and further confirmed with high resolution transmission electron microscopy. Powder diffraction and electron microscopy study show that ball milling of starting elemental powders (V-4Cr-4Ti) with and without yttria addition has resulted in single phase α-V (V-4Cr-4Ti) alloy. Wherein, XRD and electron microscopy images of sintered samples have revealed phase separation (viz., Cr-V and Ti-V) and domain size reduction, with yttria addition. The reasons behind phase separation and domain size reduction with yttria addition during sintering are extensively discussed. Microhardness and high temperature compression tests were done on sintered samples. Yttria addition (0.3 and 0.6 at.%) increases the elevated temperature compressive strength and strain hardening exponent of α-V alloys. High temperature compression test of 0.9 at% yttria dispersed α-V alloy reveals a glassy behaviour.

  9. Nanomechanical properties, wear resistance and in-vitro characterization of Ta2O5 nanotubes coating on biomedical grade Ti-6Al-4V.

    PubMed

    Sarraf, Masoud; Razak, Bushroa Abdul; Nasiri-Tabrizi, Bahman; Dabbagh, Ali; Kasim, Noor Hayaty Abu; Basirun, Wan Jefrey; Bin Sulaiman, Eshamsul

    2017-02-01

    Tantalum pentoxide nanotubes (Ta 2 O 5 NTs) can dramatically raise the biological functions of different kinds of cells, thus have promising applications in biomedical fields. In this study, Ta 2 O 5 NTs were prepared on biomedical grade Ti-6Al-4V alloy (Ti64) via physical vapor deposition (PVD) and a successive two-step anodization in H 2 SO 4 : HF (99:1)+5% EG electrolyte at a constant potential of 15V. To improve the adhesion of nanotubular array coating on Ti64, heat treatment was carried out at 450°C for 1h under atmospheric pressure with a heating/cooling rate of 1°Cmin - 1 . The surface topography and composition of the nanostructured coatings were examined by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS), to gather information about the corrosion behavior, wear resistance and bioactivity in simulated body fluids (SBF). From the nanoindentation experiments, the Young's modulus and hardness of the 5min anodized sample were ~ 135 and 6GPa, but increased to ~ 160 and 7.5GPa, respectively, after annealing at 450°C. It was shown that the corrosion resistance of Ti64 plates with nanotubular surface modification was higher than that of the bare substrate, where the 450°C annealed specimen revealed the highest corrosion protection efficiency (99%). Results from the SBF tests showed that a bone-like apatite layer was formed on nanotubular array coating, as early as the first day of immersion in simulated body fluid (SBF), indicating the importance of nanotubular configuration on the in-vitro bioactivity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Microstructure and Properties of a Refractory NbCrMo0.5Ta0.5ZrTi Alloy (Preprint)

    DTIC Science & Technology

    2011-10-01

    slightly enriched with Nb , Mo and Ta and depleted with Zr and Cr, and its lattice parameter after HIP was a = 324.76 ± 0.16 pm. The BCC2 phase was...FCC phase was highly enriched with Cr and it was identified as a Laves C15 phase, ( Zr ,Ta)(Cr,Mo, Nb )2, with the lattice parameter a = 733.38 ± 0.18 pm...with Nb , Mo and Ta and depleted with Zr and Cr, and its lattice parameter after HIP was a = 324.76 ± 0.16 pm. The BCC2 phase was enriched with Zr and Ti

  11. Examination of Multiphase (Zr,Ti)(V,Cr,Mn,Ni)2 Ni-MH Electrode Alloys: Part II. Solid-State Transformation of the Interdendritic B2 Phase

    NASA Astrophysics Data System (ADS)

    Bendersky, L. A.; Wang, K.; Boettinger, W. J.; Newbury, D. E.; Young, K.; Chao, B.

    2010-08-01

    Solidification microstructure of multicomponent (Zr,Ti)-Ni-(V,Cr,Mn,Co) alloys intended for use as negative electrodes in Ni-metal hydride (Ni-MH) batteries was studied in Part I of this series of articles. Part II of the series examines the complex internal structure of the interdendritic grains formed by solid-state transformation and believed to play an important role in the electrochemical charge/discharge characteristics of the overall alloy composition. By studying one alloy, Zr21Ti12.5V10Cr5.5Mn5.1Co5.0Ni40.2Al0.5Sn0.3, it is shown that the interdendritic grains solidify as a B2 (Ti,Zr)44(Ni,TM)56 phase, and then undergo transformation to Zr7Ni10-type, Zr9Ni11-type, and martensitic phases. The transformations obey orientation relationships between the high-temperature B2 phase and the low-temperature Zr-Ni-type intermetallics, and consequently lead to a multivariant structure. The major orientation relationship for the orthorhombic Zr7Ni10 type is [011]Zr7Ni10//[001]B2; (100)Zr7Ni10//(100)B2. The orientation relationship for the tetragonal Zr9Ni11 type is [001]Zr9Ni11//[001]B2; (130)Zr9Ni11//(100)B2. Binary Ni-Zr and ternary Ti-Ni-Zr phase diagrams were used to rationalize the formation of the observed domain structure.

  12. HYDRATE v1.5 OPTION OF TOUGH+ v1.5

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

    Moridis, George

    HYDRATE v1.5 is a numerical code that for the simulation of the behavior of hydrate-bearing geologic systems, and represents the third update of the code since its first release [Moridis et al., 2008]. It is an option of TOUGH+ v1.5 [Moridis and Pruess, 2014], a successor to the TOUGH2 [Pruess et al., 1999, 2012] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. HYDRATE v1.5 needs the TOUGH+ v1.5 core code in order to compile and execute. It is written in standard FORTRAN 95/2003, and can be run on any computational platformmore » (workstation, PC, Macintosh) for which such compilers are available. By solving the coupled equations of mass and heat balance, the fully operational TOUGH+HYDRATE code can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH 4-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy's law is valid. TOUGH+HYDRATE v1.5 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH 4, hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dissociation or formation, phase changes and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects.« less

  13. High-temperature heat capacity of CdO-V2O5 oxides

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Chumilina, L. G.; Belousova, N. V.; Denisov, V. M.; Galiakhmetova, N. A.

    2017-12-01

    Vanadates Cd2V2O7 and CdV2O6 have been prepared from CdO i V2O5 by three-phase synthesis with subsequent burning at 823-1073 K and 823-853 K, respectively. The molar heat capacity of these oxide compounds has been measured by differential scanning calorimetry. The enthalpy change, the entropy change, and the reduced Gibbs energy are calculated using the experimental dependences C p = f( T). It is shown that there is a correlation between the specific heat capacity and the composition of CdO-V2O5 oxide system.

  14. Synthesis, structure and electrical properties of Cu 3.21Ti 1.16Nb 2.63O 12 and the CuO x-TiO 2-Nb 2O 5 pseudoternary phase diagram

    NASA Astrophysics Data System (ADS)

    Reeves-McLaren, Nik; Ferrarelli, Matthew C.; Tung, Yuan-Wei; Sinclair, Derek C.; West, Anthony R.

    2011-07-01

    Subsolidus phase relations in the CuO x-TiO 2-Nb 2O 5 system were determined at 935 °C. The phase diagram contains one new phase, Cu 3.21Ti 1.16Nb 2.63O 12 (CTNO) and one rutile-structured solid solution series, Ti 1-3 xCu xNb 2 xO 2: 0< x<0.2335 (35). The crystal structure of CTNO is similar to that of CaCu 3Ti 4O 12 (CCTO) with square planar Cu 2+ but with A site vacancies and a disordered mixture of Cu +, Ti 4+ and Nb 5+ on the octahedral sites. It is a modest semiconductor with relative permittivity ˜63 and displays non-Arrhenius conductivity behavior that is essentially temperature-independent at the lowest temperatures.

  15. Highly efficient visible-light driven photocatalytic hydrogen production from a novel Z-scheme Er3+:YAlO3/Ta2O5-V5+||Fe3+-TiO2/Au coated composite

    NASA Astrophysics Data System (ADS)

    Wang, Guowei; Ma, Xue; Wei, Shengnan; Li, Siyi; Qiao, Jing; Wang, Jun; Song, Youtao

    2018-01-01

    In this work, the preparation of a novel Z-scheme photocatalyst, Er3+:YAlO3/Ta2O5-V5+||Fe3+-TiO2/Au coated composite, for visible-light photocatalytic hydrogen production is reported for the first time. In this photocatalyst, Au nanoparticles as conduction band co-catalyst provide more active sites to enrich electrons. Ta2O5-V5+||Fe3+-TiO2 as composite redox cycle system thoroughly separates the photo-generated electrons and holes. In addition, Er3+:YAlO3 as up-conversion luminescence agent (from visible-light to ultraviolet-light) provides enough ultraviolet-light for satisfying the energy demand of wide band-gap semiconductors (TiO2 and Ta2O5). The photocatalytic hydrogen production can be achieved from methanol as sacrificial agent (electron donor) under visible-light irradiation. The main influence factors such as initial solution pH and molar ratio of TiO2 and Ta2O5 on visible-light photocatalytic hydrogen production activity of Er3+:YAlO3/Ta2O5-V5+||Fe3+-TiO2/Au coated composite are discussed in detail. The results show that the Er3+:YAlO3/Ta2O5-V5+||Fe3+-TiO2/Au coated composite with 1.0:0.5 M ratio of TiO2 and Ta2O5 in methanol aqueous solution at pH = 6.50 displays the highest photocatalytic hydrogen production activity. Furthermore, a high level of photocatalytic activity can be still maintained within three cycles under the same conditions. It implies that the prepared Z-scheme Er3+:YAlO3/Ta2O5-V5+||Fe3+-TiO2/Au coated composite may be a promising photocatalyst utilizing solar energy for hydrogen production.

  16. Particle Characteristics and Densification of W6Mo5Cr4V2Co5Nb Overspray Powder

    NASA Astrophysics Data System (ADS)

    Pi, Ziqiang; Lu, Xin; Yang, Fei; Liu, Bowen; Jia, Chengchang; Qu, Xuanhui; Zheng, Wei; Wu, Lizhi; Shao, Qingli

    2018-05-01

    W6Mo5Cr4V2Co5Nb (825 K) alloy was prepared by a two-step sintering process from overspray 825 K alloy powder. The overspray powder characteristics and the microstructure and mechanical properties of the as-sintered 825 K alloy were investigated. Results showed that two types of carbides formed a network structure in the overspray powder, which had spherical or quasispherical shape: one was MC carbide that was rich in vanadium (V), and the other was M2C carbide enriched with vanadium (V) and tungsten (W). The sintered 825 K alloy contained M6C and MC carbides, of which M6C was rich in tungsten (W) and molybdenum (Mo), and both of these two carbides were uniformly distributed in the alloy matrix. The alloy had relative density of 98.43%, hardness of HRC 51.8, and superior bending strength of 2042 MPa. These mechanical properties can meet the requirements of most engineering applications.

  17. A comparison of the fatigue behavior of cast Ti-7.5Mo with c.p. titanium, Ti-6Al-4V and Ti-13Nb-13Zr alloys.

    PubMed

    Lin, Chia-Wei; Ju, Chien-Ping; Chern Lin, Jiin-Huey

    2005-06-01

    The purpose of the present study is to compare the high-cycle fatigue behavior of newly developed Ti-7.5Mo alloy with that of c.p. Ti, Ti-13Nb-13Zr and Ti-6Al-4V alloys in their as-cast state. Experimental results indicate that Ti-6Al-4V and c.p. Ti have higher stress-controlled fatigue resistance but lower strain-controlled fatigue resistance than Ti-7.5Mo and Ti-13Nb-13Zr. Among four materials Ti-7.5Mo demonstrates the best strain-controlled fatigue performance. The fracture surfaces of the present materials are comprised of three morphologically distinct zones: crack initiation zone, crack propagation zone, and the final-stage overload zone. The fatigue cracks almost always initiate from casting-induced surface/subsurface pores. A river pattern is observed in the propagation zone. In the overload zone dimples are typically observed. Three factors most significantly affecting the fatigue performance of the present materials are the presence of the casting-induced surface/subsurface pores; the location of the pores; and the inherent mechanical properties of the materials.

  18. [CrIII(NCMe)6]3+--a labile CrIII source enabling formation of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue-type magnetic materials.

    PubMed

    Nelson, Kendric J; Daniels, Matthew C; Reiff, William M; Troff, Shayla A; Miller, Joel S

    2007-11-26

    The kinetic inertness of the hexaaquachromium(III) (kH2O=2.4x10(-6) s(-1)) has led to challenges with respect to incorporating CrIII ions into Prussian blue-type materials; however, hexakis(acetonitrile)chromium(III) was shown to be substantially more labile (approximately 10(4) times) and enables a new synthetic route for the synthesis of these materials via nonaqueous solvents. The synthesis, spectroscopic, and physical properties of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue analogues synthesized from [CrIII(NCMe)6]3+ and the corresponding [MIII(CN)6]3- are described. All these compounds {(NEt4)0.02CrIII[VIII(CN)6]0.98(BF4)(0.08).0.10MeCN (1), CrIII[CrIII(CN)6].0.16MeCN (2), CrIII[MnIII(CN)6].0.10MeCN (3), and (NEt4)0.04CrIII0.64CrIV0.40[FeII(CN)6]0.40[FeIII(CN)6]0.60(BF4)(0.16).1.02MeCN (4)} are ferrimagnets exhibiting cluster-glass behavior. Strong antiferromagnetic coupling was observed for M=V, Cr, and Mn with Weiss constants (theta) ranging from -132 to -524 K; and in 2, where the strongest coupling is observed (theta=-524 K), the highest Tc (110 K) value was observed. Weak antiferromagnetic coupling was observed for M=Fe (theta=-12 K) leading to the lowest Tc (3 K) value in this series. Weak coupling and the low Tc value observed in 4 were additionally contributed by the presence of both [FeII(CN)6]4- and [FeIII(CN)6]3- as confirmed by 57Fe-Mössbauer spectroscopy.

  19. Effect of V2O5 Addition on the Phase Composition of Bi5FeTi3O15 Ceramic and RF/Microwave Dielectric Properties

    NASA Astrophysics Data System (ADS)

    Aguiar, F. A. A.; Sales, A. J. M.; Araújo, B. S.; Sabóia, K. D. A.; Filho, M. C. Campos; Sombra, A. S. B.; Ayala, A. P.; Fechine, P. B. A.

    2017-04-01

    Bi5FeTi3O15 (BFT) polycrystalline ceramic with the addition of different concentrations of V2O5 was obtained by a solid-state method. X-ray powder diffraction, Raman spectroscopy and scanning electron microscopy (SEM) were used to study the microstructure and crystalline phases of the ceramics. SEM images showed plate-like morphology with dimensions between 0.32 μm and 3.07 μm (grain size, average around 1.3 μm). For samples with V2O5 concentration below 5%, Raman spectra were mainly determined by the vibrational modes from BFT. Impedance spectroscopy was also performed to evaluate the dielectric properties at microwave and radio frequencies (RF). Two extra phases (Bi4V1.5Fe0.5O10.5 and Bi2Ti2O7) were found due to the chemical reaction between BFT and V2O5. These phases were responsible for the changes in the grain morphology and dielectric response. V2O5 addition increased the real part of the dielectric permittivity ( ɛ') and reduced the dielectric loss tangent (tan δ) values at the RF range of 10 Hz to 1 MHz. For microwave frequencies of 3-3.5 GHz, ɛ' and temperature coefficient of resonant frequency ( τ f) values ranged from 66.52 ppm/°C to 88.60 ppm/°C and -304.3 ppm/°C to -192.6 ppm/°C, respectively. Thereby, BFT ceramics with added V2O5 are good candidates to be used for microwave devices (e.g., cell phones).

  20. A novel ethanol gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures

    PubMed Central

    Wang, Yuan; Liu, Lixin; Meng, Chuanmin; Zhou, Yun; Gao, Zhao; Li, Xuhai; Cao, Xiuxia; Xu, Liang; Zhu, Wenjun

    2016-01-01

    Much greater surface-to-volume ratio of hierarchical nanostructures renders them attract considerable interest as prototypical gas sensors. In this work, a novel resistive gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures is fabricated by a facile one-step synthetic process and the ethanol sensing performance of this device is characterized systematically, which shows faster response/recovery behavior, better selectivity, and higher sensitivity of about 9 times as compared to the pure TiO2 nanofibers. The enhanced sensitivity of the TiO2/Ag0.35V2O5 branched nanoheterostructures should be attributed to the extraordinary branched hierarchical structures and TiO2/Ag0.35V2O5 heterojunctions, which can eventually result in an obvious change of resistance upon ethanol exposure. This study not only indicates the gas sensing mechanism for performance enhancement of branched nanoheterostructures, but also proposes a rational approach to design nanostructure based chemical sensors with desirable performance. PMID:27615429

  1. A novel ethanol gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Liu, Lixin; Meng, Chuanmin; Zhou, Yun; Gao, Zhao; Li, Xuhai; Cao, Xiuxia; Xu, Liang; Zhu, Wenjun

    2016-09-01

    Much greater surface-to-volume ratio of hierarchical nanostructures renders them attract considerable interest as prototypical gas sensors. In this work, a novel resistive gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures is fabricated by a facile one-step synthetic process and the ethanol sensing performance of this device is characterized systematically, which shows faster response/recovery behavior, better selectivity, and higher sensitivity of about 9 times as compared to the pure TiO2 nanofibers. The enhanced sensitivity of the TiO2/Ag0.35V2O5 branched nanoheterostructures should be attributed to the extraordinary branched hierarchical structures and TiO2/Ag0.35V2O5 heterojunctions, which can eventually result in an obvious change of resistance upon ethanol exposure. This study not only indicates the gas sensing mechanism for performance enhancement of branched nanoheterostructures, but also proposes a rational approach to design nanostructure based chemical sensors with desirable performance.

  2. Growth (AlCrNbSiTiV)N thin films on the interrupted turning and properties using DCMS and HIPIMS system

    NASA Astrophysics Data System (ADS)

    Chang, Kai-Sheng; Chen, Kuan-Ta; Hsu, Chun-Yao; Hong, Po-Da

    2018-05-01

    This paper determines the optimal settings in the deposition parameters for (AlCrNbSiTiV)N high-entropy alloy (HEAs) nitride films that are deposited on CBN cutting tools and glass substrates. We use direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HIPIMS), with Ar plasma and N2 reactive gases. Experiments with the grey-Taguchi method are conducted to determine the effect of deposition parameters (deposition time, substrate DC bias, DC power and substrate temperature) on interrupted turning 50CrMo4 steel machining and the films' structural properties. Experimental result shows that the multiple performance characteristics for these (AlCrNbSiTiV)N HEAs film coatings can be improved using the grey-Taguchi method. As can be seen, the coated film is homogeneous, very compact and exhibits perfect adherence to the substrate. The distribution of elements is homogeneous through the depth of the (AlCrNbSiTiV)N film, as measured by an auger electron nanoscope. After interrupted turning with an (AlCrNbSiTiV)N film coated tool, we obtain much longer tool life than when using uncoated tools. The correlation of these results with microstructure analysis and tool life indicates that HIPIMS discharge induced a higher (AlCrNbSiTiV)N film density, a smoother surface structure and a higher hardness surface.

  3. Half-metallicity in new Heusler alloys NaTO2 (T=Sc, Ti, V, Cr, and Mn): A first-principles study

    NASA Astrophysics Data System (ADS)

    Rajabi, Kh; Ahmadian, F.

    2018-03-01

    On the basis of the full-potential linearized augmented plane wave (FPLAPW) method within density functional theory (DFT), electronic structure and magnetic properties of Heusler alloys NaTO2 (T = Sc, Ti, V, Cr, and Mn) were investigated. The negative values of formation energy showed that these compounds can be experimentally synthesized. Results showed that in all compounds, AlCu2Mn-type structure was the most favorable one. The NaTO2 (T = Sc, Ti, V, Cr, and Mn) alloys were HM ferromagnets except NaScO2 (in both structures which were nonmagnetic semiconductors) and NaVO2 (in AlCu2Mn-type structure which was a magnetic semiconductor). The origin of half-metallicity was also verified in HM alloys. NaCrO2 and NaVO2 alloys had higher half-metallic band gaps in comparison with Heusler alloys including and excluding transition metals. The total magnetic moments of HM NaTO2 (T = Ti, V, Cr, and Mn) alloys obeyed Slater-Pauling rule (Mtot = Ztot-12). Among NaTO2 (T = Sc, Ti, V, Cr, and Mn) alloys, NaCrO2 had the highest robustness of half-metallicity with variation of lattice constant in both structures.

  4. Enhanced electrostricitive properties and thermal endurance of textured (Bi0.5Na0.5)TiO3-BaTiO3-(K0.5Na0.5)NbO3 ceramics

    NASA Astrophysics Data System (ADS)

    Hao, Jigong; Ye, Chenggen; Shen, Bo; Zhai, Jiwei

    2013-08-01

    Textured 0.92(Bi0.5Na0.5)TiO3-0.06BaTiO3-0.02(K0.5Na0.5)NbO3 (BNT-BT-KNN) ceramics have been produced by tape casting with pure-phase (Bi0.5Na0.5)TiO3 templates. Through the approach of texture construction, enhanced electrostrictive response was obtained with an electrostrictive coefficient Q33 (˜0.024 m4/C2 at 60 kV/cm) and good thermostability comparable with that of traditional Pb-based electrostrictors. Even at an electric-field as low as 35 kV/cm or at a temperature as high as 180 °C, samples still possess a large electrostrictive response with Q33 > 0.022 m4/C2, suggesting it is very promising for practical applications as a lead-free electrostrictive material owning to its wide usage range. Moreover, reducing the applied electric-filed or increasing temperature can both induce the predominant to pure electrostriction transition due to the little contributions of electrostriction strain from ferroelectric domain switching. Our work may provide a new recipe for designing high-performance BNT-based lead-free electrostrictive materials by means of texture construction.

  5. Cr3+ and Nb5+ co-doped Ti2Nb10O29 materials for high-performance lithium-ion storage

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Yu, Shu; Ma, Yu; Lin, Chunfu; Xu, Zhihao; Zhao, Hua; Wu, Shunqing; Zheng, Peng; Zhu, Zi-Zhong; Li, Jianbao; Wang, Ning

    2017-08-01

    Ti2Nb10O29 is an advanced anode material for lithium-ion batteries due to its large specific capacity and high safety. However, its poor electronic/ionic conductivity significantly limits its rate capability. To tackle this issue, a Cr3+-Nb5+ co-doping is employed, and a series of CrxTi2-2xNb10+xO29 compounds are prepared. The co-doping does not change the Wadsley-Roth shear structure but increases the unit-cell volume and decreases the particle size. Due to the increased unit-cell volumes, the co-doped samples show increased Li+-ion diffusion coefficients. Experimental data and first-principle calculations reveal significantly increased electronic conductivities arising from the formation of impurity bands after the co-doping. The improvements of the electronic/ionic conductivities and the smaller particle sizes in the co-doped samples significantly contribute to improving their electrochemical properties. During the first cycle at 0.1 C, the optimized Cr0.6Ti0.8Nb10.6O29 sample delivers a large reversible capacity of 322 mAh g-1 with a large first-cycle Coulombic efficiency of 94.7%. At 10 C, it retains a large capacity of 206 mAh g-1, while that of Ti2Nb10O29 is only 80 mAh g-1. Furthermore, Cr0.6Ti0.8Nb10.6O29 shows high cyclic stability as demonstrated in over 500 cycles at 10 C with tiny capacity loss of only 0.01% per cycle.

  6. Crystal Chemistry and Conductivity Studies in the System La 0.5+ x+ yLi 0.5-3 xTi 1-3 yCr 3 yO 3

    NASA Astrophysics Data System (ADS)

    Martínez-Sarrión, M. L.; Mestres, L.; Morales, M.; Herraiz, M.

    2000-12-01

    The stoichiometry polymorphism and electrical behavior of solid solutions La0.5+x+yLi0.5-3xTi1-3yCr3yO3 with perovskite-type structure were studied. Data are given in the form of a solid solutions triangle, phase diagrams, XRD patterns for the three polymorphs, A, β, and C, composition dependence of their lattice parameters, and ionic and electronic conductivity plots. Microstructure and composition were studied by SEM/EDS and electron probe microanalysis. These compounds are mixed conductors. Ionic conductivity decreased when the amount of lithium diminished and electronic conductivity increased with chromium content.

  7. Comparative study on the structure and electrochemical hydriding properties of MgTi, Mg 0.5Ni 0.5Ti and MgTi 0.5Ni 0.5 alloys prepared by high energy ball milling

    NASA Astrophysics Data System (ADS)

    Rousselot, Steeve; Guay, Daniel; Roué, Lionel

    MgTi, Mg 0.5Ni 0.5Ti and MgTi 0.5Ni 0.5 alloys doped with 10 wt.% Pd were prepared by high energy ball milling and evaluated as hydrogen storage electrodes for Ni-MH batteries. X-ray diffraction analyses indicated that the Mg 0.5Ni 0.5Ti and MgTi 0.5Ni 0.5 alloys could be monophased or composed of a nanoscale mixture of MgTi + NiTi and MgTi + MgNi phases, respectively. Their hydrogen storage characteristics were investigated electrochemically in KOH electrolyte. No activation step was observed during the cycling of the Mg-Ti-Ni electrodes in contrast to that observed with the MgTi electrode. The highest hydrogen discharge capacity was obtained with the MgTi 0.5Ni 0.5 electrode (536 mAh g -1) compared to 401 and 475 mAh g -1 for the Mg 0.5Ni 0.5Ti and MgTi electrodes, respectively. The ternary Mg-Ti-Ni alloys showed a better cycle life with an average capacity decay rate per cycle lower than 1.5% compared to ∼7% for the binary MgTi electrode. The Mg-Ni-Ti electrodes also displayed a much higher discharge rate capability than the binary MgTi electrode, especially with the Mg 0.5Ni 0.5Ti electrode. The origin of this was established on the basis of the anodic polarization curves, where a substantial decrease of the concentration overpotential (reflecting a higher hydrogen diffusivity) was observed for the Mg 0.5Ni 0.5Ti electrode.

  8. Effect of the microstructure of Ti-5Mo on the anodic dissolution in H/sub 2/SO/sub 4/

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

    Kim, Y.J.; Oriani, R.A.

    1987-04-01

    The effect of microstructure of the Ti-5Mo alloy on its anodic dissolution rate in sulfuric acid solution at various temperatures has been investigated. TiMo alloys exhibit a region of increased dissolution rate in the vicinity of +0.20 V (saturated calomel electrode (SCE)) in 10% H/sub 2/SO/sub 4/, the same potential region in which pure Mo exhibits a large anodic dissolution rate. Aging of Ti-5Mo at 350 C was found to lead to the formation of ..omega.. phase. Heat treatment caused larger passive currents in 10% H/sub 2/SO/sub 4/, but the critical passivation potentials and corrosion potentials were not significantly affected.more » Molybdenum was enriched in the oxide formed on aged Ti-5Mo at +0.23 V (SCE), in comparison with the Mo concentration found in the oxide on as-received Ti-5Mo.« less

  9. 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.

  10. Synthesis, structure and electrical properties of Cu{sub 3.21}Ti{sub 1.16}Nb{sub 2.63}O{sub 12} and the CuO{sub x}-TiO{sub 2}-Nb{sub 2}O{sub 5} pseudoternary phase diagram

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

    Reeves-McLaren, Nik, E-mail: n.reeves@sheffield.ac.uk; Ferrarelli, Matthew C.; Tung, Yuan-Wei

    2011-07-15

    Subsolidus phase relations in the CuO{sub x}-TiO{sub 2}-Nb{sub 2}O{sub 5} system were determined at 935 deg. C. The phase diagram contains one new phase, Cu{sub 3.21}Ti{sub 1.16}Nb{sub 2.63}O{sub 12} (CTNO) and one rutile-structured solid solution series, Ti{sub 1-3x}Cu{sub x}Nb{sub 2x}O{sub 2}: 0Ti{sub 4}O{sub 12} (CCTO) with square planar Cu{sup 2+} but with A site vacancies and a disordered mixture of Cu{sup +}, Ti{sup 4+} and Nb{sup 5+} on the octahedral sites. It is a modest semiconductor with relative permittivity {approx}63 and displays non-Arrhenius conductivity behavior that ismore » essentially temperature-independent at the lowest temperatures. - Graphical abstract: The CuO{sub x}-TiO{sub 2}-Nb{sub 2}O{sub 5} phase diagram was determined at 935 deg. C and contains one new phase, Cu{sub 3.21}Ti{sub 1.16}Nb{sub 2.63}O{sub 12}, pictured, a modest semiconductor with {epsilon}{sub r}{approx}63, and one rutile-structured solid solution series, Ti{sub 1-3x}Cu{sub x}Nb{sub 2x}O{sub 2}. Highlights: > Subsolidus phase relations in the CuO{sub x}-TiO{sub 2}-Nb{sub 2}O{sub 5} system were determined at 935 deg. C. > A new phase, Cu{sub 3.21}Ti{sub 1.16}Nb{sub 2.63}O{sub 12} (CTNO), was found with a CaCu{sub 3}Ti{sub 4}O{sub 12}-like crystal structure. > We discovered one rutile-structured solid solution series, Ti{sub 1-3x}Cu{sub x}Nb{sub 2x}O{sub 2}: 0 CTNO has square planar Cu{sup 2+}, A site vacancies and Cu{sup +}, Ti{sup 4+} and Nb{sup 5+} disordered on octahedral sites. > CTNO is a modest semiconductor with relative permittivity {approx}63.« less

  11. Effect of the Heat-Treated Ti6Al4V Alloy on the Fibroblastic Cell Response

    PubMed Central

    Chávez-Díaz, Mercedes Paulina; Escudero-Rincón, María Lorenza; Arce-Estrada, Elsa Miriam; Cabrera-Sierra, Román

    2017-01-01

    Two heat treatments were carried out below (Ti6Al4V800) and above (Ti6Al4V1050) Ti6Al4V beta-phase transformation temperature (980 °C), with the purpose of studying the effect of microstructure on the adhesion and proliferation of fibroblast cells, as well as their electrochemical behavior. These alloys were seeded with 10,000 L929 fibroblast cells and immersed for 7 days in the cell culture at 37 °C, pH 7.40, 5% CO2 and 100% relative humidity. Cell adhesion was characterized by Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS) techniques. Polygonal and elongated cell morphology was observed independent of Ti6Al4V microstructure. Besides, C, O, P, S, Na and Cl signals were detected by Energy Dispersive X-Ray Spectroscopy (EDX), associated with the synthesis of organic compounds excreted by the cells, including protein adsorption from the medium. In certain areas on Ti6Al4V and Ti6Al4V800 alloys, cells were agglomerated (island type), likely related to the globular microstructure; meanwhile, larger cellular coverage is shown for Ti6Al4V1050 alloy, forming more than one layer on the surface, where only Ca was recorded. Impedance diagrams showed a similar passive behavior for the different Ti6Al4V alloys, mainly due to TiO2 overlaying the contribution of the organic compounds excreted by fibroblast cells. PMID:29301205

  12. High temperature hydrothermal synthesis of rare-earth titanates: synthesis and structure of RE5Ti4O15(OH) (RE = La, Er), Sm3TiO5(OH)3, RE5Ti2O11(OH) (RE = Tm-Lu) and Ce2Ti4O11.

    PubMed

    Fulle, Kyle; Sanjeewa, Liurukara D; McMillen, Colin D; Kolis, Joseph W

    2018-05-15

    Reactions of rare-earth oxides with TiO2 were performed in high temperature (650-700 °C) hydrothermal fluids. Two different mineralizer fluids were examined, 20 M KOH and 30 M CsF, and their respective products analyzed. When concentrated KOH fluids were used, single crystals of a variety of new OH- containing species were isolated and structurally characterized: RE5Ti4O15(OH) (RE = La, Er) I, Sm3TiO5(OH)3II and RE5Ti2O11(OH) (RE = Tm-Lu) III. La5Ti4O15(OH) I crystallizes in the orthorhombic space group Pnnm with unit cell dimensions of a = 30.5152(12) Å, b = 5.5832(2) Å, c = 7.7590(3) Å and V = 1321.92(9) Å3, Z = 4. Sm3TiO5(OH)3II crystallizes in the monoclinic space group P21/m with unit cell parameters of a = 5.6066(2) Å, b = 10.4622(4) Å, c = 6.1258(2) Å and β = 104.7390(10)°, V = 347.50(2) Å3, Z = 2. Lu5Ti2O11(OH) III crystallizes in the monoclinic space group C2/m with unit cell dimensions of a = 12.1252(9) Å, b = 5.8243(4) Å, c = 7.0407(5) Å, β = 106.939(3)° and V = 475.65(6) Å3, Z = 2. When concentrated fluoride solutions are used, mostly RE2Ti2O7 type compounds were isolated in either cubic or monoclinic phases. In the case of cerium, Ce2Ti4O11IV was isolated that crystallizes in the monoclinic space group C2/c with unit cell parameters of a = 13.6875(7) Å, b = 5.0955(3) Å, c = 12.8592(7) Å, β = 108.964(2)° and V = 848.18(8) Å3, Z = 4. The synthesis, structural characterization, and supporting characterization are reported for all compounds. The work highlights the complementary nature of hydroxide and fluoride fluids in studying the reactivity of refractory oxides.

  13. Thermophysical Properties of Solid and Liquid Ti-6Al-4V (TA6V) Alloy

    NASA Astrophysics Data System (ADS)

    Boivineau, M.; Cagran, C.; Doytier, D.; Eyraud, V.; Nadal, M.-H.; Wilthan, B.; Pottlacher, G.

    2006-03-01

    Ti-6Al-4V (TA6V) titanium alloy is widely used in industrial applications such as aeronautic and aerospace due to its good mechanical properties at high temperatures. Experiments on two different resistive pulse heating devices (CEA Valduc and TU-Graz) have been carried out in order to study thermophysical properties (such as electrical resistivity, volume expansion, heat of fusion, heat capacity, normal spectral emissivity, thermal diffusivity, and thermal conductivity) of both solid and liquid Ti-6Al-4V. Fast time-resolved measurements of current, voltage, and surface radiation and shadowgraphs of the volume have been undertaken. At TU-Graz, a fast laser polarimeter has been used for determining the emissivity of liquid Ti-6Al-4V at 684.5 nm and a differential scanning calorimeter (DSC) for measuring the heat capacity of solid Ti-6Al-4V. This study deals with the specific behavior of the different solid phase transitions (effect of heating rate) and the melting region, and emphasizes the liquid state ( T > 2000 K).

  14. Surface structure and electrochemical characteristics of Ti-V-Cr bcc-type solid solution alloys sintered with Ni

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

    Tsuji, Yoichiro; Yamamoto, Osamu; Matsuda, Hiromu

    2000-07-01

    Ti-V-Cr bcc-type solid solution alloys can absorb a large amount of hydrogen and be applied to active materials of the negative electrode in Ni-MH batteries. However, because of the insolubility of Ni into these alloys, the electrochemical characteristics like discharge capacity and cycle life were poor. In order to increase the discharge capacity of hydrogen absorbing alloy electrodes, Ti-V-Cr bcc-type alloy powders were sintered with Ni in order to form Ni contained surface layer on the alloy surface. As sintering temperature rose up, the surface composition changed from TiNi to Ti{sub 2}Ni. TiNi surface layer showed better electrochemical characteristics. Formore » the Ni adding method, Ni electroless plating was preferred because of good adhesion. As a result of optimized conditions, a discharge capacity of 570 mAh/g and an improvement of cycle life were achieved.« less

  15. Ultrasonic Characterization of Microstructural Changes in Ti-10V-4.5Fe-1.5Al β-Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Viswanath, A.; Kumar, Anish; Jayakumar, T.; Purnachandra Rao, B.

    2015-08-01

    Ultrasonic measurements have been carried out in Ti-10V-4.5Fe-1.5Al β-titanium alloy specimens subjected to β annealing at 1173 K (900 °C) for 1 hour followed by heat treatment in the temperature range of 823 K to 1173 K (550 °C to 900 °C) at an interval of 50 K (50 °C) for 1 hour, followed by water quenching. Ultrasonic parameters such as ultrasonic longitudinal wave velocity, ultrasonic shear wave velocity, shear anisotropy parameter, ultrasonic attenuation, and normalized nonlinear ultrasonic parameter have been correlated with various microstructural changes to understand the interaction of the propagating ultrasonic wave with microstructural features in the alloy. Simulation studies using JMatPro® software and X-ray diffraction measurements have been carried out to estimate the α-phase volume fraction in the specimens heat treated below the β-transus temperature (BTT). It is found that the α-phase (HCP) volume fraction increases from 0 to 52 pct, with decrease in the temperature from 1073 K to 823 K (800 °C to 550 °C). Ultrasonic longitudinal and shear wave velocities are found to increase with decrease in the heat treatment temperature below the BTT, and they exhibited linear relationships with the α-phase volume fraction. Thickness-independent ultrasonic parameters, Poisson's ratio, and the shear anisotropy parameter exhibited the opposite behavior, i.e., decrease with increase in the α-phase consequent to decrease in the heat treatment temperature from 1073 K to 823 K (800 °C to 550 °C). Ultrasonic attenuation is found to decrease from 0.7 dB/mm for the β-annealed specimen to 0.23 dB/mm in the specimen heat treated at 823 K (550 °C) due to the combined effect of the decrease in the β-phase (BCC) with higher damping characteristics and the reduction in scattering due to randomization of β grains with the precipitation of α-phase. Normalized nonlinear ultrasonic parameter is found to increase with increase in the α-phase volume fraction

  16. Surface preparation of Ti-3Al-2.5V alloy tubes for welding using a fiber laser

    NASA Astrophysics Data System (ADS)

    Kumar, Aniruddha; Gupta, Mool C.

    2009-11-01

    Ti-3Al-2.5V tubes are widely used in aircraft hydraulic systems. Meticulous surface preparation before welding is necessary to obtain a sound weld involving these alloy tubes. Conventionally this is done by cleaning with environmentally malign toxic chemicals, such as, hydrofluoric acid and nitric acid. This paper describes the laser-cleaning process of the surface of these tubes with a fiber laser as a preparation for pulsed gas tungsten arc welding and results obtained. A simple one-dimensional heat equation has been solved to evaluate the temperature profile of the irradiated surface. It is shown that surface preparation by laser cleaning can be an environmentally friendly alternative process by producing acceptable welds with laser-processed tubes.

  17. Chromium doping as a new approach to improve the cycling performance at high temperature of 5 V LiNi 0.5Mn 1.5O 4-based positive electrode

    NASA Astrophysics Data System (ADS)

    Aklalouch, Mohamed; Amarilla, José Manuel; Rojas, Rosa M.; Saadoune, Ismael; Rojo, José María

    LiCr 2 YNi 0.5- YMn 1.5- YO 4 (0 < Y ≤ 0.2) spinels have been synthesized by a sucrose-aided combustion method. Two sets of Cr-doped samples have been obtained by heating the "as-prepared" samples at 700 and 900 °C for 1 h. X-ray diffraction and thermogravimetric data show that pure and single phase spinels with similar lattice parameter have been synthesized. The homogeneity and the sub-micrometric particle size of the spinels have been shown by SEM and TEM. The main effect of the temperature is to increase the particle size from ≈50 to ≈500 nm, on heating from 700 to 900 °C. The study of the influence of Cr-dopant content and thermal treatment on the electrochemical properties at 25 °C and at 55 °C has been carried out by galvanostatic cycling in Li-cells. The discharge capacity (≈130 mAh g -1) does not noticeably change with the synthesis conditions; but the cycling performances are strongly modified. Key factors that control the cycling performances have been determined. The most highlighted result is that spinels heated at 900 °C with Y ≤ 0.1 have very high capacity retention at 55 °C (>96% after 40 cycles, cyclability >99.9% by cycle) indicating that metal doping is a new approach to prepare 5 V LiNi 0.5Mn 1.5O 5-based cathodes with excellent cycling performances at high temperature.

  18. Microstructure and wear property of the Ti5Si3/TiC reinforced Co-based coatings fabricated by laser cladding on Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Weng, Fei; Yu, Huijun; Liu, Jianli; Chen, Chuanzhong; Dai, Jingjie; Zhao, Zhihuan

    2017-07-01

    Ti5Si3/TiC reinforced Co-based composite coatings were fabricated on Ti-6Al-4V titanium alloy by laser cladding with Co42 and SiC mixture. Microstructure and wear property of the cladding coatings with different content of SiC were investigated. During the cladding process, the original SiC dissolved and reacted with Ti forming Ti5Si3 and TiC. The complex in situ formed phases were found beneficial to the improvement of the coating property. Results indicated that the microhardness of the composite coatings was enhanced to over 3 times the substrate. The wear resistance of the coatings also showed distinct improvement (18.4-57.4 times). More SiC gave rise to better wear resistance within certain limits. However, too much SiC (20 wt%) was not good for the further improvement of the wear property.

  19. Dislocations and charge density distributions of {gamma} phase in Ti47.5Al2.5V deformed at room temperature and 400 {degree}C

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

    Zhu, J.; Gao, Y.; Miao, Y.

    The observations on quantity and configuration of dislocations by TEM conventional diffraction contrast method as well as the determinations of the electron charge density distributions by the quantitative electron crystallography method in Ti47.5Al2.5V deformed at 400 C and room temperature (R.T.) have been carried out. The metallic bonding between Al-Al or Ti-Ti atom pair along {l_angle}110] and Ti-Ti along {l_angle}112] direction is strengthened; while the metallic bonding between Ti-Al atom pair both along {l_angle}101] and {l_angle}121] direction is weakened at 400 C. The quantities of a/2{l_angle}110], a/2{l_angle}112] and dissociated a{l_angle}101] (a[101]{yields}a/2[1{bar 1}0] + a/3[112] + SISF + a/6[112]) dislocations aremore » increased at 400 C, compared with that at R. T.. The a/2 {l_angle}121] super dislocations have not been seen both at 400 C and R.T.« less

  20. Preparation and UV-Vis photodegradation of gaseous benzene by TiO2 nanotube arrays supporting V2O5 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Chunxia; Song, Yanbao; Yang, Yunxia; Chen, Wen; Li, Xiaoyu; Wang, Zongsheng

    2015-07-01

    TiO2-based catalysts effective in visible radiation for eliminating organic pollutants have attracted intense research activity as a future generation photocatalytic material. However, recombination of electron-hole pairs through trapping/de-trapping as well as the disadvantages of recycling and separation/filtration of powders lead to the limitation of powder TiO2 materials. TiO2 nanotube array films supporting vanadium pentoxide nanoparticles (VTNTs) were synthesized by electrophoresis deposition method with the prepared TiO2 nanotube arrays as the cathode and V2O5 sol as the electrolyte. The results indicate that the formation of Ti-O-V bonds and intimate interaction between host-guest interfaces help to enhance the hybrids’ photodegradation activity of gaseous benzene. Importantly, hybrid film catalysts prepared with 0.05 mol/L V2O5 sol for 10 min electrophoresis deposition perform a 98% conversion rate of benzene and 1028.8 mg/m3CO2 production in 80 min under UV-Vis irradiation.

  1. Ti 3CrCu 4: A possible 2-D ferromagnetic spin fluctuating system

    DOE PAGES

    Dhar, S. K.; Provino, A.; Manfrinetti, P.; ...

    2016-03-09

    Ti 3CrCu 4 is a new ternary compound which crystallizes in the tetragonal Ti 3Pd 5 structure type. The Cr atoms form square nets in the a-b plane (a = 3.124 Å) which are separated by an unusually large distance c = 11.228 Å along the tetragonal axis, thus forming a -2-D Cr-sublattice. The paramagnetic susceptibility is characterized by a low effective moment, μ eff = 1.1 μ B, a low paramagnetic Curie temperature θ P (below 7 K) and a temperature independent χ0 = 6.7 x 10 –4 emu/mol. The magnetization at 1.8 K increases rapidly with field nearlymore » saturating to 0.2 μ B/f.u. The zero field heat capacity C/T shows an upturn below 7 K (~190 mJ/mol K 2 at ~0.1K) which is suppressed in applied magnetic fields and interpreted as suggesting the presence of spin fluctuations. The resistivity at low temperatures shows non-Fermi liquid behavior. Overall, the experimental data thus reveal an unusual magnetic state in Ti 3CrCu 4, which likely has its origin in the layered nature of the Cr sub-lattice and ferromagnetic spin fluctuations. Here, density functional theoretical calculations reveal a sharp Cr density of states peak just above the Fermi level, indicating the propensity of Ti 3CrCu 4 to become magnetic.« less

  2. Excitation functions of the natCr(p,x)44Ti, 56Fe(p,x)44Ti, natNi(p,x)44Ti and 93Nb(p,x)44Ti reactions at energies up to 2.6 GeV

    NASA Astrophysics Data System (ADS)

    Titarenko, Yu. E.; Batyaev, V. F.; Pavlov, K. V.; Titarenko, A. Yu.; Zhivun, V. M.; Chauzova, M. V.; Balyuk, S. A.; Bebenin, P. V.; Ignatyuk, A. V.; Mashnik, S. G.; Leray, S.; Boudard, A.; David, J. C.; Mancusi, D.; Cugnon, J.; Yariv, Y.; Nishihara, K.; Matsuda, N.; Kumawat, H.; Stankovskiy, A. Yu.

    2016-06-01

    The paper presents the measured cumulative yields of 44Ti for natCr, 56Fe, natNi and 93Nb samples irradiated by protons at the energy range 0.04-2.6 GeV. The obtained excitation functions are compared with calculations of the well-known codes: ISABEL, Bertini, INCL4.2+ABLA, INCL4.5+ABLA07, PHITS, CASCADE07 and CEM03.02. The predictive power of these codes regarding the studied nuclides is analyzed.

  3. Structure and Mechanical Properties of CrTiAlN/TiAlN Composite Coatings Deposited by Multi-Arc Ion Plating

    NASA Astrophysics Data System (ADS)

    Yan, Shaojian; Tian, Canxin; Huang, Zhihong; Yang, Bing; Fu, Dejun

    2014-10-01

    CrTiAlN/TiAlN composite coatings were deposited on cemented carbide by using a home-made industrial scale multi-arc ion plating system. The samples were studied by X-ray diffraction, scanning electron microscopy (SEM), microhardness and ball-on-disk testing. The properties of the CrTiAlN/TiAlN coatings were significantly influenced by the microstructure and the deposition time ratio of TiAlN over CrTiAlN layers. With the increase of deposition time ratio, the microhardness of CrTiAlN/TiAlN increased from 28.6 GPa to 37.5 GPa, much higher than that of CrTiAlN coatings. The friction coefficients of the CrTiAlN/TiAlN coatings were higher than those of CrTiAlN coatings against a cemented carbide ball. The microhardness of the CrTiAlN/TiAlN coatings was changed after annealing at 800°C, and the friction coefficients of the annealed coatings were increased against the cemented carbide ball.

  4. A high-response ethanol gas sensor based on one-dimensional TiO2/V2O5 branched nanoheterostructures

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Zhou, Yun; Meng, Chuanmin; Gao, Zhao; Cao, Xiuxia; Li, Xuhai; Xu, Liang; Zhu, Wenjun; Peng, Xusheng; Zhang, Botao; Lin, Yifeng; Liu, Lixin

    2016-10-01

    Hierarchical nanostructures with much increased surface-to-volume ratio have been of significant interest for prototypical gas sensors. Herein we report a novel resistive gas sensor based on TiO2/V2O5 branched nanoheterostructures fabricated by a facile one-step synthetic process, in which well-matched energy levels induced by the formation of effective heterojunctions between TiO2 and V2O5, a large Brunauer-Emmett-Teller surface area and complete electron depletion for the V2O5 nanobranches induced by the branched-nanofiber structures are all beneficial to the change of resistance upon ethanol exposure. As a result, the ethanol sensing performance of this device shows a lower operating temperature, faster response/recovery behavior, better selectivity and about seven times higher sensitivity compared with pure TiO2 nanofibers. This study not only confirms the gas sensing mechanism for performing enhancement of branched nanoheterostructures, but also proposes a rational approach to the design of nanostructure-based chemical sensors with desirable performance.

  5. Heavy ion irradiations on synthetic hollandite-type materials: Ba1.0Cs0.3A2.3Ti5.7O16 (A=Cr, Fe, Al)

    NASA Astrophysics Data System (ADS)

    Tang, Ming; Tumurugoti, Priyatham; Clark, Braeden; Sundaram, S. K.; Amoroso, Jake; Marra, James; Sun, Cheng; Lu, Ping; Wang, Yongqiang; Jiang, Ying.-Bing.

    2016-07-01

    The hollandite supergroup of minerals has received considerable attention as a nuclear waste form for immobilization of Cs. The radiation stability of synthetic hollandite-type compounds described generally as Ba1.0Cs0.3A2.3Ti5.7O16 (A=Cr, Fe, Al) were evaluated by heavy ion (Kr) irradiations on polycrystalline single phase materials and multiphase materials incorporating the hollandite phases. Ion irradiation damage effects on these samples were examined using grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). Single phase compounds possess tetragonal structure with space group I4/m. GIXRD and TEM observations revealed that 600 keV Kr irradiation-induced amorphization on single phase hollandites compounds occurred at a fluence between 2.5×1014 Kr/cm2 and 5×1014 Kr/cm2. The critical amorphization fluence of single phase hollandite compounds obtained by in situ 1 MeV Kr ion irradiation was around 3.25×1014 Kr/cm2. The hollandite phase exhibited similar amorphization susceptibility under Kr ion irradiation when incorporated into a multiphase system.

  6. (Ba1- x Bi0.33 x Sr0.67 x )(Ti1- x Bi0.67 x V0.33 x )O3 and (Ba1- x Bi0.5 x Sr0.5 x )(Ti1- x Bi0.5 x Ti0.5 x )O3 solid solutions: phase evolution, microstructure, dielectric properties and impedance analysis

    NASA Astrophysics Data System (ADS)

    Chen, Xiuli; Li, Xiaoxia; Yan, Xiao; Liu, Gaofeng; Zhou, Huanfu

    2018-06-01

    Perovskite solid solution ceramics of (Ba1- x Bi0.33 x Sr0.67 x )(Ti1- x Bi0.67 x V0.33 x )O3 and (Ba1- x Bi0.5 x Sr0.5 x )(Ti1- x Bi0.5 x Ti0.5 x )O3 (BBSTBV, BBSTBT, 0.02 ≤ x ≤ 0.2) were prepared by the traditional solid state reaction technique. The phase evolution, microstructure and dielectric properties of BBSTBV and BBSTBT ceramics were researched. X-Ray diffraction results illustrated that both BBSTBV and BBSTBT could form a homogenous solid solution which has a similar structure with BaTiO3. The optimized properties of (Ba0.8Bi0.1Sr0.1)(Ti0.8Bi0.1Ti0.1)O3 ceramics with stable ɛ r ( 1769-2293), small Δ ɛ/ ɛ 25 °C values (± 15%) over a broad temperature range from - 58 to 151 °C and low tan δ ≤ 0.03 from - 11 to 131 °C were obtained. In the high-temperature region, the relaxation and conduction process are attributed to the thermal activation and the oxygen vacancies may be the ionic charge carriers in perovskite ferroelectrics.

  7. Preparation of TiO2/(TiO2-V2O5)/polypyrrole nanocomposites and a study on catalytic activities of the hybrid materials under UV/Visible light and in the dark

    NASA Astrophysics Data System (ADS)

    Piewnuan, C.; Wootthikanokkhan, J.; Ngaotrakanwiwat, P.; Meeyoo, V.; Chiarakorn, S.

    2014-11-01

    Hybrid metal oxides/polymer nanocomposites, namely TiO2/(TiO2-V2O5)/polypyrrole (PPy), were synthesized via in situ polymerization. Structures of the products were characterized by SEM-EDX, XRD, and FTIR techniques. The light absorbance and band gap energy values of the materials were evaluated by UV/Visible spectroscopy. The catalytic activity of the materials was determined from a degradation of methylene blue. It was found that, regardless of the polymerization time, the absorbance of TiO2/(TiO2-V2O5)/PPy was greater than those of TiO2/PPy and the neat TiO2, respectively. This was in accordance with the decrease in the band gap energy of the materials. The catalytic activity of TiO2/(TiO2-V2O5) was also observed in the dark. After polymerization, the catalytic activity of nanocomposite under UV/Visible light and in the dark was compromised. The above effects are discussed in the light of the energy storage ability of V2O5 and capability of the polymer in acting as a binder for the system.

  8. Electronic stopping power of Ti, V and Cr ions in Ge and Au at 150-500 keV/u energies

    NASA Astrophysics Data System (ADS)

    Linares, R.; Ribas, R. V.; Oliveira, J. R. B.; Medina, N. H.; Santos, H. C.; Seabra, C. C.; Sigaud, L.; Cybulska, E. W.; Seale, W. A.; Allegro, P. R. P.; Touffen, D. L.; Silveira, M. A. G.

    2017-12-01

    In this paper new experimental data are presented for the stopping power of Ti, V and Cr ions in Ge and Au, in the 150-500 keV/u energy range. The heavy ions at low energies are produced from the elastic scattering between particles of an energetic primary beam (28Si and 16O) directed onto the primary foil of interest (Ti, V or Cr). Measurements were performed using the transmission method. New experimental data points for the stopping power of Ti in Au were compared with previous measurement. The agreement between these two datasets indicates the consistence of the experimental technique. Our experimental data were also compared to some selected theoretical and semi-empirical methods: i) the Unitary Convolution Approximation, ii) the Binary theory, iii) the SRIM code and iv) the Northcliffe & Schilling tables. The experimental data for Ge foil deviate from the theoretical curves possibly due to the effect of band gap structure of the material in the electronic stopping power. For the systems measured here, we observe that the Binary theory exhibits an overall good agreement. The velocity-proportional dependence of the electronic stopping power in the measured energy range is also discussed.

  9. Ab initio prediction of half-metallic properties for the ferromagnetic Heusler alloys Co2MSi (M=Ti,V,Cr)

    NASA Astrophysics Data System (ADS)

    Chen, Xing-Qiu; Podloucky, R.; Rogl, P.

    2006-12-01

    By means of density functional calculations, the magnetic and electronic properties and phase stabilities of the Heusler compounds Co2MSi (with M =Ti,V,Cr,Mn,Fe,Co,Ni) were investigated. Based on the calculated results, we predict the ferromagnetic phases of the compounds Co2TiSi, Co2VSi, and Co2CrSi to be half metals. Of particular interest is Co2CrSi because of its high density of majority-spin states at Fermi energy in combination with a reasonably high estimated Curie temperature of 747K. The compounds Co2TiSi and Co2VSi are thermodynamically stable, whereas Co2CrSi is of a metastable phase which might be stabilized by suitable experimental techniques.

  10. Tensile properties of cast titanium alloys: Titanium-6Al-4V ELI and Titanium-5Al-2.5Sn ELI

    NASA Technical Reports Server (NTRS)

    Billinghurst, E. E., Jr.

    1992-01-01

    This work was performed to determine the tensile properties of cast, hot isostatic pressed (HIP'ed), and annealed titanium alloys, Ti-6Al-4V ELI and Ti-5Al-2.5Sn ELI, that are candidate materials for the space transportation main engine (STME) liquid hydrogen turbopump impeller. Samples of the cast alloys were HIP'ed, annealed, and machined into tensile specimens. The specimens were tested in air at ambient temperature (70 F) and also at -423 F in liquid hydrogen. The Ti-6Al-4V alloy had an average ultimate strength of 129.1 ksi at 70 F and 212.2 ksi at -423 F. The Ti-5Al-2.5Sn alloy had an average ultimate strength of 108.4 ksi at 70 degrees F and 185.0 ksi at -423 F. The ductility, as measured by reduction of area, for the Ti-6Al-4V averaged 15.2 percent at 70 F and 8.7 percent at -423 F, whereas for the Ti-5Al-2.5Sn alloy average reduction of area was 24.6 percent at 70 F and 11.7 percent at -423 F.

  11. Wear Behavior of Low-Cost, Lightweight TiC/Ti-6Al-4V Composite Under Fretting: Effectiveness of Solid-Film Lubricant Counterparts

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Sanders, Jeffrey H.; Hager, Carl H., Jr.; Zabinski, Jeffrey S.; VanderWal, Randall L.; Andrews, Rodney; Lerch, Bradley A.

    2007-01-01

    The wear behavior of low-cost, lightweight 10-wt% TiC-particulate-reinforced Ti-6Al-4V matrix composite (TiC/Ti- 6Al-4V) was examined under fretting at 296, 423, and 523 K in air. Bare 10-wt% TiC/Ti-6Al-4V hemispherical pins were used in contact with dispersed multiwalled carbon nanotubes (MWNTs), magnetron-sputtered diamondlike carbon/chromium (DLC/Cr), magnetron-sputtered graphite-like carbon/chromium (GLC/Cr), and magnetron-sputtered molybdenum disulphide/titanium (MoS2/Ti) deposited on Ti-6Al-4V, Ti-48Al-2Cr-2Nb, and nickel-based superalloy 718. When TiC/Ti-6Al-4V was brought into contact with bare Ti-6Al-4V, bare Ti-48Al-2Cr-2Nb, and bare nickel-based superalloy 718, strong adhesion, severe galling, and severe wear occurred. However, when TiC/Ti-6Al-4V was brought into contact with MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings, no galling occurred in the contact, and relatively minor wear was observed regardless of the coating. All the solid-film lubricants were effective from 296 to 523 K, but the effectiveness of the MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings decreased as temperature increased.

  12. Grindability of cast Ti-6Al-4V alloyed with copper.

    PubMed

    Watanabe, Ikuya; Aoki, Takayuki; Okabe, Toru

    2009-02-01

    This study investigated the grindability of cast Ti-6Al-4V alloyed with copper. The metals tested were commercially pure titanium (CP Ti), Ti-6Al-4V, experimental Ti-6Al-4V-Cu (1, 4, and 10 wt% Cu), and Co-Cr alloy. Each metal was cast into five blocks (3.0 x 8.0 x 30.0 mm(3)). The 3.0-mm wide surface of each block was ground using a hand-piece engine with an SiC wheel at four circumferential speeds (500, 750, 1000, and 1250 m/min) at a grinding force of 100 g. The grindability index (G-index) was determined as volume loss (mm(3)) calculated from the weight loss after 1 minute of grinding and the density of each metal. The ratio of the metal volume loss and the wheel volume loss was also calculated (G-ratio, %). Data (n = 5) were statistically analyzed using ANOVA (alpha= 0.05). Ti-6Al-4V and the experimental Ti-6Al-4V-Cu alloys exhibited significantly (p < 0.05) higher G-indexes compared with CP Ti and Co-Cr at any rotational speed except for the lowest speed (500 m/min). At 500 m/min, the G-index of Ti-6Al-4V-Cu increased as the amount of alloyed copper increased. The 4% Cu and 10% Cu alloys had significantly greater G-indexes than did 1% Cu and Ti-6Al-4V at the highest rotational speed (1250 m/min). Increasing the percentage of alloyed copper and the circumferential speed also increased the G-ratio. A slight reduction in ductility due to alloying Ti-6Al-4V with copper improved the grindability of some of the resultant Ti-6Al-4V-Cu alloys.

  13. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity.

    PubMed

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2009-02-06

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10 microm, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants.

  14. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity

    PubMed Central

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2008-01-01

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10 μm, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants. PMID:18664431

  15. Low temperature destruction of PCDD/Fs over V2O5-CeO2/TiO2 catalyst with ozone.

    PubMed

    Yu, Ming-Feng; Lin, Xiao-Qing; Yan, Mi; Li, Xiao-Dong; Chen, Tong; Yan, Jian-Hua

    2016-09-01

    Catalytic destruction of PCDD/Fs (polychlorinated dibenzo-p-dioxins and furans) over V2O5-CeO2/TiO2 catalyst was investigated at a low temperature range of 140-180 °C, in the absence and presence of ozone (200 ppm). Nano-TiO2 support was used to prepare the catalyst by step impregnation method. A stable PCDD/Fs-generating system was established to support the catalytic destruction tests. In the presence of ozone alone, destruction efficiencies of PCDD/Fs are between 32.2 and 43.1 % with temperature increasing from 140 to 180 °C. The activity of V2O5-CeO2/TiO2 catalyst alone on PCDD/Fs destruction is also studied. The increase of temperature from 140 to 180 °C enhances the activity of catalyst with destruction efficiencies increasing from 54.7 to 73.4 %. However, ozone addition greatly enhances the catalytic activity of V2O5-CeO2/TiO2 catalyst on PCDD/Fs decomposition. At 180 °C, the destruction efficiency of PCDD/Fs achieved with V2O5-CeO2/TiO2 catalyst and ozone is above 86.0 %. It indicates that the combined use of ozone and catalyst reduces the reaction temperature of PCDD/Fs oxidation and offers a new method to destroy PCDD/Fs with high destruction efficiency at a low temperature. Furthermore, the destruction efficiencies of 17 toxic PCDD/F congeners, achieved with ozone alone, catalyst alone, and catalyst/ozone are analyzed.

  16. Evaluation of flow properties in the weldments of vanadium alloys using a novel indentation technique

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

    Gubbi, A.N.; Rowcliffe, A.F.; Lee, E.H.

    1996-10-01

    Automated Ball Indentation (ABI) testing, was successfully employed to determine the flow properties of the fusion zone, heat affected zone (HAZ), and base metal of the gas tungsten arc (GTA) and electron beam (EB) welds of the V-4Cr-4Ti (large heat no. 832665) and the V-5Cr-5Ti (heat 832394) alloys. ABI test results showed a clear distinction among the properties of the fusion zone, HAZ, and base metal in both GTA and EB welds of the two alloys. GTA and EB welds of both V-4Cr-4Ti and V-5Cr-5Ti alloys show strengthening of both the fusion zone and the HAZ (compared to base metal)more » with the fusion zone having higher strength than the HAZ. These data correlate well with the Brinell hardness. On the other hand, GTA welds of both alloys, after a post-weld heat treatment of 950{degrees}C for 2 h, show a recovery of the properties to base metal values with V-5Cr-5Ti showing a higher degree of recovery compared to V-4Cr-4Ti. These measurements correlate with the reported recovery of the Charpy impact properties.« less

  17. High temperature tensile properties of V-4Cr-4Ti

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

    Zinkle, S.J.; Rowcliffe, A.F.; Stevens, C.O.

    Tensile tests have been performed on V-4Cr-4Ti at 750 and 800 C in order to extend the data base beyond the current limit of 700 C. From comparison with previous measurements, the yield strength is nearly constant and tensile elongations decrease slightly with increasing temperature between 300 and 800 C. The ultimate strength exhibits an apparent maximum near 600 C (attributable to dynamic strain aging) but adequate strength is maintained up to 800 C. The reduction in area measured on tensile specimens remained high ({approximately}80%) for test temperatures up to 800 C, in contrast to previous reported results.

  18. STRUCTURAL, ELASTIC AND MECHANICAL PROPERTIES OF TMN (TM = Ti, V, Cr): A DFT STUDY

    NASA Astrophysics Data System (ADS)

    Jiao, Zhao-Yong; Niu, Yi-Jun; Ma, Shu-Hong; Huang, Xiao-Fen

    2013-08-01

    Mechanical properties and the effect of metallic bonding on the hardness of transition-metal nitrides (TiN, VN and CrN) compounds are studied using the first-principles calculation. Present results show that these transition-metal nitrides are mechanically stable and the VN and CrN are ductile, whereas TiN is predicted to be brittle. Moreover, it is found that the high hardness of TiN, VN and CrN exhibits a remarkable decrease with transition-metal changed from Ti to Cr, and the metallic d-d interactions play important roles on determining the hardness of transition-metal nitrides.

  19. Cyclic electrical conductivity in BaTiO3-PbTiO3-V2O5 glass-ceramic nanocomposite

    NASA Astrophysics Data System (ADS)

    Bahgat, A. A.; Heikal, Sh.; Mahdy, Iman A.; Abd-Rabo, A. S.; Abdel Ghany, A.

    2014-08-01

    In this present work a glass of the composition 22.5 BaTiO3+7.5 PbTiO3+70 V2O5 was prepared by applying the conventional melt quashing technique. Isothermal annealing of the glass was applied at 732 K following differential scanning calorimetric analysis. The annealing was performed during different time intervals in the range of 0.25-24.0 h. X-ray diffraction and transmission electron microscopy were used to identify different phases as well as particle size precipitated during the annealing process. Nanocomposite glass-ceramic precipitation was recognized with nonperiodic cyclic particle sizes as a function of the annealing period. DC electrical conductivity, on the other hand, was conducted in the temperature range from 300 to 625 K. Electrical conductivity enhancement of the order 3×103 times after 2.5 h of annealing was observed. Nonperiodic cyclic DC electrical conductivity behavior was also observed and which was encountered in a reverse manner with particle size development. Furthermore, the analysis of the electrical conduction mechanism predicts that both adiabatic and nonadiabatic small polaron hopping trend may describe the experimental data depending on the particle size.

  20. Effect of mechanical alloying and heat treatment on the behavior of fe - 28% al - 5% cr powder with nanocrystalline structure

    NASA Astrophysics Data System (ADS)

    Tang, W. M.; Liu, H. L.; Wang, Y. X.; Xu, G. O.; Zheng, Z. X.

    2012-05-01

    Nanocrystalline powders of alloy Fe - 28% Al - 5% Cr (at.%) obtained by mechanical alloying from powdered iron, aluminum, and preliminarily alloyed Fe - 20% Cr are studied. The chemical composition is shown to be homogenized. The changes in the structure and in the morphology of the particles in the process of ball milling and subsequent heat treatment are determined. The alloying is shown to occur by the mechanism of continuous diffusion mixing.

  1. In situ disordering of monoclinic titanium monoxide Ti5O5 studied by transmission electron microscope TEM.

    PubMed

    Rempel, А А; Van Renterghem, W; Valeeva, А А; Verwerft, M; Van den Berghe, S

    2017-09-07

    The superlattice and domain structures exhibited by ordered titanium monoxide Ti 5 O 5 are disrupted by low energy electron beam irradiation. The effect is attributed to the disordering of the oxygen and titanium sublattices. This disordering is caused by the displacement of both oxygen and titanium atoms by the incident electrons and results in a phase transformation of the monoclinic phase Ti 5 O 5 into cubic B1 titanium monoxide. In order to determine the energies required for the displacement of titanium or oxygen atoms, i.e. threshold displacement energies, a systematic study of the disappearance of superstructure reflections with increasing electron energy and electron bombardment dose has been performed in situ in a transmission electron microscope (TEM). An incident electron energy threshold between 120 and 140 keV has been observed. This threshold can be ascribed to the displacements of titanium atoms with 4 as well as with 5 oxygen atoms as nearest neighbors. The displacement threshold energy of titanium atoms in Ti 5 O 5 corresponding with the observed incident electron threshold energy lies between 6.0 and 7.5 eV. This surprisingly low value can be explained by the presence of either one or two vacant oxygen lattice sites in the nearest neighbors of all titanium atoms.

  2. Formation of Cr-modified silicide coatings on a Ti-Nb-Si based ultrahigh-temperature alloy by pack cementation process

    NASA Astrophysics Data System (ADS)

    Qiao, Yanqiang; Guo, Xiping

    2010-10-01

    Cr-modified silicide coatings were prepared on a Ti-Nb-Si based ultrahigh temperature alloy by Si-Cr co-deposition at 1250 °C, 1350 °C and 1400 °C for 5-20 h respectively. It was found that both coating structure and phase constituents changed significantly with increase in the co-deposition temperature and holding time. The outer layers in all coatings prepared at 1250 °C for 5-20 h consisted of (Ti,X) 5Si 3 (X represents Nb, Cr and Hf elements). (Ti,X) 5Si 4 was found as the only phase constituent in the intermediate layers in both coatings prepared at 1250 °C for 5 and 10 h, but the intermediate layers in the coatings prepared at 1250 °C for 15 and 20 h were mainly composed of (Ti,X) 5Si 3 phase that was derived from the decomposition of (Ti,X) 5Si 4 phase. In the coating prepared at 1350 °C for 5 h, single (Ti,X) 5Si 3 phase was found in its outmost layer, the same as that in the outer layers in the coatings prepared at 1250 °C; but in the coatings prepared at 1350 °C for 10-20 h, (Nb 1.95Cr 1.05)Cr 2Si 3 ternary phase was found in the outmost layers besides (Ti,X) 5Si 3 phase. In the coatings prepared at 1400 °C for 5-20 h, (Nb 1.95Cr 1.05)Cr 2Si 3 ternary phase was the single phase constituent in their outmost layers. The phase transformation (Ti,X) 5Si 4 → (Ti,X) 5Si 3 + Si occurred in the intermediate layers of the coatings prepared at 1350 and 1400 °C with prolonging co-deposition time, similar to the situation in the coatings prepared at 1250 °C for 15 and 20 h, but this transformation has been speeded up by increase in the co-deposition temperature. The transitional layers were mainly composed of (Ti,X) 5Si 3 phase in all coatings. The influence of co-deposition temperature on the diffusion ability of Cr atoms was greater than that of Si atoms in the Si-Cr co-deposition processes investigated. The growth of coatings obeyed inverse logarithmic laws at all three co-deposition temperatures. The Si-Cr co-deposition coating prepared at 1350

  3. Evaluation of Ti-48Al-2Cr-2Nb Under Fretting Conditions

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Lerch, Bradley A.; Draper, Susan L.; Raj, Sai V.

    2001-01-01

    The fretting behavior of Ti-48Al-2Cr-2Nb (y-TiAl) in contact with the nickel-base superalloy 718 was examined in air at temperatures from 296 to 823 K (23 to 550 C). The interfacial adhesive bonds between Ti-48Al-2Cr-2Nb and superalloy 718 were generally stronger than the cohesive bonds within Ti-48Al-2Cr-2Nb. The failed Ti-48Al-2Cr-2Nb debris subsequently transferred to the superalloy 718. In reference experiments conducted with Ti-6Al-4V against superalloy 718 under identical fretting conditions, the degree of transfer was greater for Ti-6A1-4V than for Ti-48Al-2Cr-2Nb. Wear of Ti-48Al-2Cr-2Nb generally decreased with increasing fretting frequency. The increasing rate of oxidation at elevated temperatures led to a drop in wear at 473 K. However, fretting wear increased as the temperature was increased from 473 to 823 K. At 723 and 823 K, oxide film disruption generated cracks, loose wear debris, and pits on the Ti-48Al-2Cr-2Nb wear surface. Both increasing slip amplitude and increasing load tended to produce more metallic wear debris, causing severe abrasive wear in the contacting metals.

  4. 28 CFR 63.5 - Responsibilities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Responsibilities. 63.5 Section 63.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) FLOODPLAIN MANAGEMENT AND WETLAND PROTECTION..., bureau, or division to see that the policy considerations and procedural requirements contained herein...

  5. 28 CFR 63.5 - Responsibilities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Responsibilities. 63.5 Section 63.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) FLOODPLAIN MANAGEMENT AND WETLAND PROTECTION..., bureau, or division to see that the policy considerations and procedural requirements contained herein...

  6. Electrolytic Production of Ti5Si3/TiC Composites by Solid Oxide Membrane Technology

    NASA Astrophysics Data System (ADS)

    Zheng, Kai; Zou, Xingli; Xie, Xueliang; Lu, Changyuan; Chen, Chaoyi; Xu, Qian; Lu, Xionggang

    2017-12-01

    This paper investigated the electrolytic production of Ti5Si3/TiC composites from TiO2/SiO2/C in molten CaCl2. The solid-oxide oxygen-ion-conducting membrane tube filled with carbon-saturated liquid tin was served as the anode, and the pressed spherical TiO2/SiO2/C pellet was used as the cathode. The electrochemical reduction process was carried out at 1273 K and 3.8 V. The characteristics of the obtained cathode products and the reaction mechanism of the electroreduction process were studied by a series of time-dependent electroreduction experiments. It was found that the electroreduction process generally proceeds through the following steps: TiO2/SiO2/C → Ti2O3, CaTiO3, Ca2SiO4, SiC → Ti5Si3, TiC. The morphology observation and the elemental distribution analysis indicate that the reaction routes for Ti5Si3 and TiC products are independent during the electroreduction process.

  7. Electrolytic Production of Ti5Si3/TiC Composites by Solid Oxide Membrane Technology

    NASA Astrophysics Data System (ADS)

    Zheng, Kai; Zou, Xingli; Xie, Xueliang; Lu, Changyuan; Chen, Chaoyi; Xu, Qian; Lu, Xionggang

    2018-02-01

    This paper investigated the electrolytic production of Ti5Si3/TiC composites from TiO2/SiO2/C in molten CaCl2. The solid-oxide oxygen-ion-conducting membrane tube filled with carbon-saturated liquid tin was served as the anode, and the pressed spherical TiO2/SiO2/C pellet was used as the cathode. The electrochemical reduction process was carried out at 1273 K and 3.8 V. The characteristics of the obtained cathode products and the reaction mechanism of the electroreduction process were studied by a series of time-dependent electroreduction experiments. It was found that the electroreduction process generally proceeds through the following steps: TiO2/SiO2/C → Ti2O3, CaTiO3, Ca2SiO4, SiC → Ti5Si3, TiC. The morphology observation and the elemental distribution analysis indicate that the reaction routes for Ti5Si3 and TiC products are independent during the electroreduction process.

  8. Adsorption of toxic metal ion Cr(VI) from aqueous state by TiO2-MCM-41: equilibrium and kinetic studies.

    PubMed

    Parida, Kulamani; Mishra, Krushna Gopal; Dash, Suresh Kumar

    2012-11-30

    This paper deals with the immobilization of various weight percentage of TiO(2) on mesoporous MCM-41, characterization of the materials by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier Transform Infrared (FTIR) analysis, UV-vis diffuse reflectance spectroscopy (DRS) and evaluation of the adsorption capacity toward Cr(VI) removal. It is found that the MCM-41 structure retained after loading of TiO(2) but the surface area and pore diameter decreased due to pore blockage. Adsorption of Cr(VI) from aqueous state was investigated on TiO(2)-MCM-41 by changing various parameters such as pH, metal ion concentration, and the temperature. When TiO(2) loading was more than 20 wt.%, the adsorption activity (25)TiO(2)-MCM-41 reduced significantly due to considerable decrease in the surface area. It is also observed that TiO(2) and neat MCM-41 exhibits very less Cr(VI) adsorption compared to TiO(2)-MCM-41. The adsorption of Cr(VI) onto (20)TiO(2)-MCM-41 at pH~5.5 and temperature 323 K was 91% at 100mg/L Cr(VI) metal ion concentration in 80 min. The experimental data fitted well to Langmuir and Freundlich isotherms. The adsorption of Cr(VI) on TiO(2)-MCM-41 followed a second order kinetics with higher values of intra-particle diffusion rate. Thermodynamic parameters suggested that the adsorption process is endothermic in nature and desorption studies indicated a chemisorption mode. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Microstructure and mechanical properties of 2.5 vol. % TiBw/Ti6Al4V composites plates fabricated by hot-hydrostatic canned extrusion

    NASA Astrophysics Data System (ADS)

    Zhang, Wencong; Zhang, Lingjia; Feng, Yangju; Cui, Guorong; Chen, Wenzhen

    2018-04-01

    Plates of 2.5 vol. % TiB whisker-reinforced Ti6Al4V titanium matrix composites (TiBw/Ti64) with network structure were successfully fabricated by hot-hydrostatic extrusion with steel cup at 1100 °C. The dimensions of plates were about 150mm in length, 27mm in width and 2mm in thickness. After extrusion, the original equiaxed-network structure formed by TiB whiskers still existed, but was compressed in cross-section and stretched in longitudinal section and then the TiB whiskers were directional distribution along the extrusion direction. Furthermore, the mechanical properties results showed that the strength, hardness and ductility of the plates were significantly improved compared to as-sintered composites.

  10. Photocatalytic activity of TiO2/Nb2O5/PANI and TiO2/Nb2O5/RGO as new nanocomposites for degradation of organic pollutants.

    PubMed

    Zarrin, Saviz; Heshmatpour, Felora

    2018-06-05

    In this study, highly active titanium dioxide modified by niobium oxide (Nb 2 O 5 ), polymer (PANI) and reduced graphene oxide (RGO) were successfully prepared. The morphology, structure, surface area and light absorption properties of the present nanocomposites for removal of methylene blue (MB) and methyl orange (MO) were investigated and compared with those of TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. The characterization techniques such as XRD, FT-IR, UV-vis, SEM, EDX, BET and TEM were employed in order to identify the nanocomposites. Also, photocatalytic properties of TiO 2 /Nb 2 O 5 /PANI and TiO 2 /Nb 2 O 5 /RGO nanocomposites under visible light irradiation were studied. In this way, the obtained results were compared to each other and also compared to TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. In this context, the chemical oxygen demand (COD) removal follows the photodegradation in observed performance. The results indicate that reduced TiO 2 /Nb 2 O 5 nanocomposite is effectively modified by graphene oxide to give TiO 2 /Nb 2 O 5 /RGO composite. The TiO 2 /Nb 2 O 5 /RGO exhibits significantly higher photocatalytic activity in degradation of organic dyes under visible light rather than that of TiO 2 /Nb 2 O 5 /PANI, TiO 2 /Nb 2 O 5 and pure TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Measurement of the controlled variable during heating of Ti6Al4V for thixoforging

    NASA Astrophysics Data System (ADS)

    Gerlach, O.; Lechler, A.; Verl, A.

    2018-02-01

    Controlled heating of metal billets into the semi-solid state for thixoforming is a challenging task, mainly due to the difficulties in measuring the liquid fraction of the billet during heating. Past research primarily focused on methods measuring the liquid fraction during heating of low-melting aluminium alloys. One of these methods is time constant measurement, a contactless measurement method that uses the heating coil as a sensor. The current through the coil is used to determine the electrical time constant of the heating circuit, which itself is influenced by the specific resistance of the billet inside the coil. While previous works focused on the suitability of this method for industrial applications using aluminum alloys, this paper extends this research to the high-melting titanium alloy Ti6Al4V. This alloys shows high strength, low density and excellent corrosion resistance. It is therefore used to produce light-weight and durable components for medical and aerospace applications. Ti6Al4V is an expensive and difficult to machine alloy. Thus, it is an interesting alloy for thixoforging. However, heating of the billet into a homogeneous state of defined liquid fraction is difficult due to the poor thermal conductivity of Ti6Al4V. This paper analyses the potential of using time constant measurement for controlled heating of Ti6Al4V into the semi-solid state.

  12. Batisivite, V8Ti6[Ba(Si2O)]O28, a new mineral species from the derbylite group

    NASA Astrophysics Data System (ADS)

    Reznitsky, L. Z.; Sklyarov, E. V.; Armbruster, T.; Galuskin, E. V.; Ushchapovskaya, Z. F.; Polekhovsky, Yu. S.; Karmanov, N. S.; Kashaev, A. A.; Barash, I. G.

    2008-12-01

    Batisivite has been found as an accessory mineral in the Cr-V-bearing quartz-diopside metamorphic rocks of the Slyudyanka Complex in the southern Baikal region, Russia. A new mineral was named after the major cations in its ideal formula (Ba, Ti, Si, V). Associated minerals are quartz, Cr-V-bearing diopside and tremolite; calcite; schreyerite; berdesinskiite; ankangite; V-bearing titanite; minerals of the chromite-coulsonite, eskolaite-karelianite, dravite-vanadiumdravite, and chernykhite-roscoelite series; uraninite; Cr-bearing goldmanite; albite; barite; zircon; and unnamed U-Ti-V-Cr phases. Batisivite occurs as anhedral grains up to 0.15-0.20 mm in size, without visible cleavage and parting. The new mineral is brittle, with conchoidal fracture. Observed by the naked eye, the mineral is black and opaque, with a black streak and resinous luster. Batisivite is white in reflected light. The microhardness (VHN) is 1220-1470 kg/mm2 (load is 30 g), the mean value is 1330 kg/mm2. The Mohs hardness is near 7. The calculated density is 4.62 g/cm3. The new mineral is weakly anisotropic and bireflected. The measured values of reflectance are as follows (λ, nm— R {max/'}/ R {min/'}): 440—17.5/17.0; 460—17.3/16.7; 480—17.1/16.5; 500—17.2/16.6; 520—17.3/16.7; 540—17.4/16.8; 560—17.5/16.8; 580—17.6/16.9; 600—17.7/17.1; 620—17.7/17.1; 640—17.8/17.1; 660—17.9/17.2; 680—18.0/17.3; 700—18.1/17.4. Batisivite is triclinic, space group P overline 1 ; the unit-cell dimensions are: a = 7.521(1) Å, b = 7.643(1) Å, c = 9.572(1) Å, α = 110.20°(1), β = 103.34°(1), γ = 98.28°(1), V = 487.14(7) Å3, Z = 1. The strongest reflections in the X-ray powder diffraction pattern [ d, Å ( I, %)( hkl)] are: 3.09(8)(12 overline 2 ); 2.84, 2.85(10)(021, 120); 2.64(8)(21 overline 3 ); 2.12(8)(31 overline 3 ); 1.785(8)(32 overline 4 ), 1.581(10)(24 overline 2 ); 1.432, 1.433(10)(322, 124). The chemical composition (electron microprobe, average of 237 point analyses

  13. Magnetic properties and structural characterization of layered (Cr0.5Mn0.5)2AuC synthesized by thermally induced substitutional reaction in (Cr0.5Mn0.5)2GaC

    NASA Astrophysics Data System (ADS)

    Lai, Chung-Chuan; Tao, Quanzheng; Fashandi, Hossein; Wiedwald, Ulf; Salikhov, Ruslan; Farle, Michael; Petruhins, Andrejs; Lu, Jun; Hultman, Lars; Eklund, Per; Rosen, Johanna

    2018-02-01

    The magnetic properties of the new phase (Cr0.5Mn0.5)2AuC are compared to the known MAX-phase (Cr0.5Mn0.5)2GaC, where the former was synthesized by thermally induced substitution reaction of Au for Ga in (Cr0.5Mn0.5)2GaC. The reaction introduced a lattice expansion of ˜3% along the c-axis, an enhancement of the coercive field from 30 mT to 140 mT, and a reduction of the Curie temperature and the saturation magnetization. Still, (Cr0.5Mn0.5)2AuC displays similar features in the magnetic field- and temperature-dependent magnetization curves as previously reported magnetic MAX phases, e.g., (Cr0.5Mn0.5)2GaC and (Mo0.5Mn0.5)2GaC. The work suggests a pathway for tuning the magnetic properties of MAX phases.

  14. Phase and crystallite size analysis of (Ti1-xMox)C-(Ni,Cr) cermet obtained by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Suryana, Anis, Muhammad; Manaf, Azwar

    2018-04-01

    In this paper, we report the phase and crystallite size analysis of (Ti1-xMox)C-(Ni,Cr) with x = 0-0.5 cermet obtained by mechanical alloying of Ti, Mo, Ni, Cr and C elemental powders using a high-energy shaker ball mill under wet condition for 10 hours. The process used toluene as process control agent and the ball to mass ratio was 10:1. The mechanically milled powder was then consolidated and subsequently heated at a temperature 850°C for 2 hours under an argon flow to prevent oxidation. The product was characterized by X-ray diffraction (XRD) and scanning electron microscope equipped with energy dispersive analyzer. Results shown that, by the selection of appropriate condition during the mechanical alloying process, a metastable Ti-Ni-Cr-C powders could be obtained. The powder then allowed the in situ synthesis of TiC-(Ni,Cr) cermet which took place during exposure time at a high temperature that applied in reactive sintering step. Addition to molybdenum has caused shifting the TiC XRD peaks to a slightly higher angle which indicated that molybdenum dissolved in TiC phase. The crystallite size distribution of TiC is discussed in the report, which showing that the mean size decreased with the addition of molybdenum.

  15. Osteoblast Cell Response on the Ti6Al4V Alloy Heat-Treated

    PubMed Central

    Chávez-Díaz, Mercedes Paulina; Escudero-Rincón, María Lorenza; Arce-Estrada, Elsa Miriam; Cabrera-Sierra, Román

    2017-01-01

    In an effort to examine the effect of the microstructural changes of the Ti6Al4V alloy, two heat treatments were carried out below (Ti6Al4V800) and above (Ti6Al4V1050) its β-phase transformation temperature. After each treatment, globular and lamellar microstructures were obtained. Saos-2 pre-osteoblast human osteosarcoma cells were seeded onto Ti6Al4V alloy disks and immersed in cell culture for 7 days. Electrochemical assays in situ were performed using OCP and EIS measurements. Impedance data show a passive behavior for the three Ti6Al4V alloys; additionally, enhanced impedance values were recorded for Ti6Al4V800 and Ti6Al4V1050 alloys. This passive behavior in culture medium is mostly due to the formation of TiO2 during their sterilization. Biocompatibility and cell adhesion were characterized using the SEM technique; Ti6Al4V as received and Ti6Al4V800 alloys exhibited polygonal and elongated morphology, whereas Ti6Al4V1050 alloy displayed a spherical morphology. Ti and O elements were identified by EDX analysis due to the TiO2 and signals of C, N and O, related to the formation of organic compounds from extracellular matrix. These results suggest that cell adhesion is more likely to occur on TiO2 formed in discrete α-phase regions (hcp) depending on its microstructure (grains). PMID:28772804

  16. Electrically insulating films deposited on V-4%Cr-4%Ti by reactive CVD

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

    Park, J.H.

    1998-04-01

    In the design of liquid-metal blankets for magnetic fusion reactors, corrosion resistance of structural materials and the magnetohydrodynamic forces and their influence on thermal hydraulics and corrosion are major concerns. Electrically insulating CaO films deposited on V-4%Cr-4%Ti exhibit high-ohmic insulator behavior even though a small amount of vanadium from the alloy become incorporated into the film. However, when vanadium concentration in the film is > 15 wt.%, the film becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. The objective of this study is to evaluate electrically insulatingmore » films that were deposited on V-4%Cr-4%Ti by a reactive chemical vapor deposition (CVD) method. To this end, CaO and Ca-V-O coatings were produced on vanadium alloys by CVD and by a metallic-vapor process to investigate the electrical resistance of the coatings. The authors found that the Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film > 0.9, and semiconductor or conductor behavior when R < 0.8. However, in some cases, semiconductor behavior was observed when CaO-coated samples with R > 0.98 were exposed in liquid lithium. Based on these studies, they conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating.« less

  17. Comparative Dielectric and Ferroelectric Characteristics of Bi0.5Na0.5TiO3, CaCu3Ti4O12, and 0.5Bi0.5Na0.5TiO3-0.5CaCu3Ti4O12 Electroceramics

    NASA Astrophysics Data System (ADS)

    Singh, Laxman; Yadava, Shiva Sundar; Sin, Byung Cheol; Rai, Uma Shanker; Mandal, K. D.; Lee, Youngil

    2016-06-01

    The dielectric and ferroelectric characteristics of Bi0.5Na0.5TiO3 (BNT), CaCu3Ti4O12 (CCTO), and 0.5Bi0.5Na0.5TiO3-0.5CaCu3Ti4O12 (BNT/CCTO) ceramics are compared. X-ray diffraction patterns confirmed the formation of single phase of all the ceramics after sintering at 950°C for 15 h. Scanning electron microscopy images of the sintered ceramics reveal average grain sizes in the range from 200 nm to 2.5 μm. Energy-dispersive x-ray mapping and x-ray photoelectron spectroscopy show the presence of the elements Bi, Na, Ca, Cu, Ti, and O with uniform distribution in the ceramics. BNT/CCTO exhibits high dielectric constant ( ɛ r ˜ 6.9 × 104) compared with BNT ( ɛ r ˜ 0.13 × 104) and CCTO ( ɛ r ˜ 1.68 × 104) ceramics at 1 kHz and 503 K. The high dielectric constant of BNT/CCTO compared with BNT and CCTO is associated with a major contribution from grain boundaries, as confirmed by impedance and modulus analyses. The P- E hysteresis loop of all the ceramics measured at room temperature and 50°C exhibited typical ferroelectric nature. The remanent polarization ( P r) of BNT (1.58 μC/cm2) and CCTO (0.654 μC/cm2) ceramics are higher than that of BNT/CCTO (0.267 μC/cm2) ceramic.

  18. Application of immobilized nanotubular TiO(2) electrode for photocatalytic hydrogen evolution: reduction of hexavalent chromium (Cr(VI)) in water.

    PubMed

    Yoon, Jaekyung; Shim, Eunjung; Bae, Sanghyun; Joo, Hyunku

    2009-01-30

    In this study, immobilized TiO(2) electrode is applied to reduce toxic Cr(VI) to non-toxic Cr(III) in aqueous solution under UV irradiation. To overcome the limitation of powder TiO(2), a novel technique of immobilization based on anodization was applied and investigated under various experimental conditions. The anodization was performed at 20V-5 degrees C for 45min with 0.5% hydrofluoric acid, and then the anodized samples were annealed under oxygen stream in the range 450-850 degrees C. Based on the results of the experiments, the photocatalytic Cr(VI) reduction was favorable in acidic conditions, with approximately 98% of the Cr(VI) being reduced within 2h at pH 3. Among the samples tested under same anodizing condition, the nanotubular TiO(2) annealed at 450 and 550 degrees C showed highest reduction efficiencies of Cr(VI). In addition, the surface characterizations (zeta potential, XRD, and SEM) of these samples proved that the Cr(VI) reduction efficiency was higher under acidic conditions and at a lower annealing temperature. From this research, it was concluded that the anodized TiO(2) has the potential to be a useful technology for environmental remediation as well as photocatalytic hydrogen production from water.

  19. Ti n O2n-1-Coated Li4Ti5O12 Composite Anode Material for Lithium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyan; Xu, Wen; Liu, Wanying; Li, Xing; Zhong, Xiaoxi; Lin, Yuanhua

    2018-01-01

    In an effort to enhance the rate capability of Li4Ti5O12, the Ti n O2n-1-coated Li4Ti5O12 (Li4Ti5O12-Ti n O2n-1, 3 < n < 10) composite has been synthesized through a sol-gel process followed by heat treatment in H2 atmosphere. Compared with pure Li4Ti5O12, Li4Ti5O12-Ti n O2n-1 composite shows higher specific capacity, better rate capability and cycle stability. The initial discharge capacity of the Li4Ti5O12-Ti n O2n-1 composite electrode is 171.2 mAh g-1 at 0.2°C, and 103.8 mAh g-1 at 20°C. Moreover, the discharge capacity remains 79.5 mAh g-1 after 100 cycles at 20°C with a capacity loss of 23.4%. The improved rate capacity and cycling stability clarify the positive effects of Ti n O2n-1 coating layer in Li4Ti5O12-Ti n O2n-1 composite as an anode material for lithium ion batteries.

  20. In situ synthesized TiB-TiN reinforced Ti6Al4V alloy composite coatings: microstructure, tribological and in-vitro biocompatibility.

    PubMed

    Das, Mitun; Bhattacharya, Kaushik; Dittrick, Stanley A; Mandal, Chitra; Balla, Vamsi Krishna; Sampath Kumar, T S; Bandyopadhyay, Amit; Manna, Indranil

    2014-01-01

    Wear resistant TiB-TiN reinforced Ti6Al4V alloy composite coatings were deposited on Ti substrate using laser based additive manufacturing technology. Ti6Al4V alloy powder premixed with 5wt% and 15wt% of boron nitride (BN) powder was used to synthesize TiB-TiN reinforcements in situ during laser deposition. Influences of laser power, scanning speed and concentration of BN on the microstructure, mechanical, in vitro tribological and biological properties of the coatings were investigated. Microstructural analysis of the composite coatings showed that the high temperature generated due to laser interaction with Ti6Al4V alloy and BN results in situ formation of TiB and TiN phases. With increasing BN concentration, from 5wt% to 15wt%, the Young's modulus of the composite coatings, measured by nanoindentation, increased from 170±5GPa to 204±14GPa. In vitro tribological tests showed significant increase in the wear resistance with increasing BN concentration. Under identical test conditions TiB-TiN composite coatings with 15wt% BN exhibited an order of magnitude less wear rate than CoCrMo alloy-a common material for articulating surfaces of orthopedic implants. Average top surface hardness of the composite coatings increased from 543±21HV to 877±75HV with increase in the BN concentration. In vitro biocompatibility and flow cytometry study showed that these composite coatings were non-toxic, exhibit similar cell-materials interactions and biocompatibility as that of commercially pure titanium (CP-Ti) samples. In summary, excellent in vitro wear resistance, high stiffness and suitable biocompatibility make these composite coatings as a potential material for load-bearing articulating surfaces towards orthopaedic implants. © 2013 Elsevier Ltd. All rights reserved.

  1. Frequency and temperature dependent dielectric properties of TiO2-V2O5 nanocomposites

    NASA Astrophysics Data System (ADS)

    Ray, Apurba; Roy, Atanu; De, Sayan; Chatterjee, Souvik; Das, Sachindranath

    2018-03-01

    In this manuscript, we have reported the crystal structure, dielectric response, and transport phenomenon of TiO2-V2O5 nanocomposites. The nanocomposites were synthesized using a sol-gel technique having different molar ratios of Ti:V (10:10, 10:15, and 10:20). The phase composition and the morphology have been studied using X-ray diffraction and field emission scanning electron microscope, respectively. The impedance spectroscopy studies of the three samples over a wide range of temperature (50 K-300 K) have been extensively described using the internal barrier layer capacitor model. It is based on the contribution of domain and domain boundary, relaxations of the materials, which are the main crucial factors for the enhancement of the dielectric response. The frequency dependent ac conductivity of the ceramics strongly obeys the well-known Jonscher's power law, and it has been clearly explained using the theory of jump relaxation model. The temperature dependent bulk conductivity is fairly recognized to the variable-range hopping of localized polarons. The co-existence of mixed valence state of Ti ions (Ti3+ and Ti4+) in the sample significantly contributes to the change of dielectric property. The overall study of dielectric response explains that the dielectric constant and the dielectric loss are strongly dependent on temperature and frequency and decrease with an increase of frequency as well as temperature.

  2. Structure and dielectric properties of Na0.5Bi0.5TiO3-CaTiO3 solid solutions

    NASA Astrophysics Data System (ADS)

    Birks, E.; Dunce, M.; Ignatans, R.; Kuzmin, A.; Plaude, A.; Antonova, M.; Kundzins, K.; Sternberg, A.

    2016-02-01

    Despite wide studies of Na0.5Bi0.5TiO3, structure of this material and its connection with the observed physical properties still raise numerous questions due to mutually contradicting results obtained. Here, structure and dielectric properties of poled and unpoled Na0.5Bi0.5TiO3-CaTiO3 solid solutions are studied, projecting the obtained concentration dependence of structure and dielectric properties on pure Na0.5Bi0.5TiO3 as the end member of this material group. X-ray diffraction patterns for Na0.5Bi0.5TiO3-CaTiO3 solid solutions reveal dominating of an orthorhombic Pnma phase, even for the compositions approaching the end composition (Na0.5Bi0.5TiO3), whereas structure of pure Na0.5Bi0.5TiO3 can be considered, assuming coexistence of rhombohedral and orthorhombic phases. This allows one to avoid appearance of a large difference of rhombohedral distortions between the unpoled and poled Na0.5Bi0.5TiO3, if the rhombohedral distortion is calculated as for single R3c phase. Features of dielectric permittivity, corresponding to the observed structural phase transition, are identified. It is discussed that the rhombohedral R3c phase is responsible for appearance of the frequency-dependent shoulder of dielectric permittivity temperature dependence, characteristic for unpoled Na0.5Bi0.5TiO3.

  3. Effect of load ratio and saltwater corrosive environment on the initiation life of fatigue of 10Ni5CrMoV steel

    NASA Astrophysics Data System (ADS)

    Xie, Xing; Yi, Hong; Xu, Jian; Gen, Liming; Chen, Luyun

    2017-09-01

    Fatigue initiation life has been studied with 10CrNi5MoV steel for use in ocean engineering at different load ratios and in different environmental media. The microstructure and micro-topography have been observed and analyzed by means of SEM, EDS and EBSD. Our findings indicate that, the initiation life of 10Ni5CrMoV steel in seawater is shorter than that in air, and the difference in longevity is larger with the increasing of load ratio. Corrosion pits had a great influence on initial corrosion fatigue life.

  4. TiO2-V2O5 nanocomposites as alternative energy storage substances for photocatalysts.

    PubMed

    Ngaotrakanwiwat, Pailin; Meeyoo, Vissanu

    2012-01-01

    TiO2-V2O5 was prepared and evaluated as an energy storage material for photocatalysts with high capacity and initial charging rate. The compound was successfully obtained by sol-gel technique and effects of compound composition and calcination temperature on the energy storage ability were investigated. The synthesized compounds were characterized by means of X-ray powder diffraction (XRD), scanning electron microscopy equipped with energy-dispersive X-ray analysis (SEM-EDX) and transmission electron microscopy (TEM). The results reveals that the compound of Ti:V molar ratio equal to 1:0.11 calcined at 550 degrees C exhibited superior energy storage ability than parent substances and 1.7-times higher capacity and 2.3-times higher initial charging rate compared to WO3, indicating that the compound is a remarkable alternative to conventional energy storage substances.

  5. The machinability of cast titanium and Ti-6Al-4V.

    PubMed

    Ohkubo, C; Watanabe, I; Ford, J P; Nakajima, H; Hosoi, T; Okabe, T

    2000-02-01

    This study investigated the machinability (ease of metal removal) of commercially pure (CP) titanium and Ti-6Al-4V alloy. Both CP Ti and Ti-6Al-4V were cast into magnesia molds. Two types of specimens (with alpha-case and without alpha-case) were made for CP Ti and Ti-6Al-4V. Machinability (n = 5) was evaluated as volume loss (mm3) by cutting/grinding the 3.0 mm surface using fissure burs and silicon carbide (SiC) under two machining conditions: (1) two machining forces (100 or 300 gf) at two rotational speeds (15000 or 30000 rpm) for 1 min, and (2) constant machining force of 100 gf and rotational speed of 15000 rpm for 1, 2, 5, 10, and 30 min. As controls, conventionally cast Co-Cr and Type IV gold alloys were evaluated in the same manner as the titanium. When fissure burs were used, there was a significant difference in the machinability between CP titanium with alpha-case and without alpha-case. On the other hand, there was no appreciable difference in the amount of metal removed for each tested metal when using the SiC points.

  6. Evaluation of metal ion release from Ti6Al4V and Co-Cr-Mo casting alloys: in vivo and in vitro study.

    PubMed

    El Sawy, Amal A; Shaarawy, Mohammed A

    2014-02-01

    The aim of this study was to evaluate the amount of ions released from Ti6Al4V and Co-Cr-Mo alloys both in vivo and in vitro. Twenty-one discs of each alloy were constructed and divided into seven groups. Three specimens from each group were immersed in a buffered saline solution over a period of 1, 3, 5, 7, 14, 21, and 28 days. Twenty-eight participants were also included in the study, where the study group consisted of 14 mandibular partially edentulous patients, and the control group consisted of 14 volunteers. The study group was further divided into two equal groups: the first group received removable partial dentures (RPDs) constructed from Co-Cr-Mo alloy, while the second group received RPDs constructed from Ti6Al4V alloy. Saliva samples were collected from each participant over the same study period. The conditioning media and saliva samples were analyzed using a spectrophotometer. One-way ANOVA and Tukey tests were used for statistical analysis (p < 0.05). The concentrations of metal ions released from the studied alloys were significantly higher in the in vitro than in the in vivo study group during the follow-up periods. A statistically significant increase in ion concentrations of the different elements for both alloys was found with time (p < 0.05). The amounts of released metallic ions from Co-Cr-Mo and Ti6Al4V alloys were higher in the buffered saline solutions than in the studied saliva samples and control groups; however, these amounts were still within the physiological limit of trace elements in the human body. © 2013 by the American College of Prosthodontists.

  7. Structure and electrical properties of 0.80 Na{sub 0.5} Bi{sub 0.5} TiO{sub 3}-0.16 K{sub 0.5} Bi{sub 0.5} TiO{sub 3}-0.04 BaTiO{sub 3} lead-free piezoelectric ceramics

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

    Aravinth, K., E-mail: aravinth.nmg@gmail.com; Babu, G. Anandha; Giridharan, N. V.

    2016-05-23

    Lead free pervoskite 0.80 Na{sub 0.5} Bi{sub 0.5} TiO{sub 3}-0.16 K{sub 0.5} Bi{sub 0.5} TiO{sub 3}-0.04 BaTiO{sub 3} (NKBBT) ceramics were fabricated via conventional solid state processing technique sintered at 1200 °C and their crystal structures and electrical properties were systematically studied. Structure of the prepared NKBBT ceramics was confirmed by Powder X-ray diffraction analysis. The dependence of dielectric constant on temperature for various frequencies (100 Hz-100 KHz) has been determined. The diffuse transition is observed in the variation of dielectric constant and it provides evidence for the relaxor characteristics. The ferroelectric response of the NKBBT ceramics with different frequencymore » was studied. Polarisation electric field hysteresis loops revealed that the remnant polarization is 6.88 µC/cm{sup 2} and coercive electric field is 66.42 kV/cm.« less

  8. 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.

  9. 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.

  10. Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

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

    Natesan, K.; Soppet, W.K.

    1997-04-01

    A test program is in progress to evaluate the effect of oxygen at low pO{sub 2} on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO{sub 2} at 500{degrees}C and reannealed in vacuum at 500{degrees}C in environments with various pO{sub 2} levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightlymore » increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO{sub 2} environments.« less

  11. Crystallographic characterizations of eutectic and secondary carbides in a Fe-12Cr-2.5Mo-1.5W-3V-1.25C alloy

    NASA Astrophysics Data System (ADS)

    Guo, Jing; Liu, Ligang; Feng, Yunli; Liu, Sha; Ren, Xuejun; Yang, Qingxiang

    2017-03-01

    In this work, the morphology and structures of the eutectic and secondary carbides in a new high chromium Fe-12Cr-2.5Mo-1.5W-3V-1.25C designed for cold-rolling work roll were systematically studied. The precipitated carbides inside the grains and along the grain boundaries were investigated with optical microscope, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy and X-Ray diffraction. Selected area diffraction patterns have been successfully used to identify the crystal formation and lattice constants of the carbides with different alloying elements. The results show that the eutectic carbides precipitated contain MC and M2C distributed along the grain boundaries with dendrite feature. The composition and crystal structure analysis shows that the eutectic MC carbides contain VC and WC with a cubic and hexagonal crystal lattice structures respectively, while the eutectic M2C carbides predominantly contain V2C and Mo2C with orthorhombic and hexagonal crystal lattices respectively. The secondary carbides contain MC, M2C, M7C3 formed along the grain boundaries and their sizes are much larger than the eutectic carbides ones. The secondary M23C6 is much small (0.3-0.5μm) and is distributed dispersively inside the grain. Similar to the eutectic carbides, the secondary carbides also contain VC, WC, V2C, and Mo2C. M7C3 is hexagonal (Fe,Cr)7C3, while M23C6 is indexed to be in a cubic crystal form.

  12. Thermal expansion properties of Ho2Fe16.5Cr0.5

    NASA Astrophysics Data System (ADS)

    Dan, Shovan; Mukherjee, S.; Mazumdar, Chandan; Ranganathan, R.

    2018-04-01

    We report the thermal expansion behavior of Ho2Fe16.5Cr0.5 compound in the range of temperature 13-483 K, using structural parameters obtained by analyzing temperature dependent x-ray diffraction (XRD) patterns. From 13 K to 300 K, the compound shows negligible thermal expansion having the coefficient of volume expansion (αV) ∼ 10-6 K -1. The thermal expansion behavior of the studied compound can be explained by the role of magnetovolume effect (MVE) below ferrimagnetic ordering temperature (394 K), in addition to normal phononic contribution. Fe sublattice contribute to MVE, whereas both the rare earth and Fe sublattice determine the value of saturation magnetization.

  13. The study of glass transition temperature in Sb-V2O5-TeO2 glasses at different heating rates

    NASA Astrophysics Data System (ADS)

    Souri, Dariush

    2015-12-01

    The glass transition of xSb-(60 - x)V2O5-40TeO2 glasses with 0 < x <15 (in mol%) at different heating rates ( φ = 3-12 K/min) has been studied using differential scanning calorimetry. The glass transition temperature ( T g) and crystallization temperature ( T cr) of these glasses have been determined. The effects of the heating rate and the Sb content on T g have been discussed. It has been observed that the transition region shifts to higher temperatures when the measuring time is reduced. The compositional dependence of T g has been determined and so an empirical equation has been deduced relating the glass transition temperature with the Sb concentration. Also, the value of glass-forming tendency has been studied for the present glasses.

  14. Oxidation behavior of V-Cr-Ti alloys in low-partial-pressure oxygen environments

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

    Natesan, K.; Uz, M.

    A test program is in progress at Argonne National Laboratory to evaluate the effect of pO{sub 2} in the exposure environment on oxygen uptake, scaling kinetics, and scale microstructure in V-Cr-Ti alloys. The data indicate that the oxidation process follows parabolic kinetics in all of the environments used in the present study. From the weight change data, parabolic rate constants were evaluated as a function of temperature and exposure environment. The temperature dependence of the parabolic rate constants was described by an Arrhenius relationship. Activation energy for the oxidation process was fairly constant in the oxygen pressure range of 1more » {times} 10{sup {minus}6} to 1 {times} 10{sup {minus}1} torr for both the alloys. The activation energy for oxidation in air was significantly lower than in low-pO{sub 2} environments, and for oxidation in pure O{sub 2} at 760 torr was much lower than in low-pO{sub 2} environments. X-ray diffraction analysis of the specimens showed that VO{sub 2} was the dominant phase in low-pO{sub 2} environments, while V{sub 2}O{sub 5} was dominant in air and in pure oxygen at 76f0 torr.« less

  15. Resistance switching mode transformation in SrRuO3/Cr-doped SrZrO3/Pt frameworks via a thermally activated Ti out-diffusion process

    PubMed Central

    Jo, Yongcheol; Jung, Kyooho; Kim, Jongmin; Woo, Hyeonseok; Han, Jaeseok; Kim, Hyungsang; Hong, Jinpyo; Lee, Jeon-Kook; Im, Hyunsik

    2014-01-01

    This work reports on a mechanism for irreversible resistive switching (RS) transformation from bipolar to unipolar RS behavior in SrRuO3 (SRO)/Cr-doped SrZrO3 (SZO:Cr)/Pt capacitor structures prepared on a Ti/SiO2/Si substrate. Counter-clockwise bipolar RS memory current-voltage (I–V) characteristics are observed within the RS voltage window of −2.5 to +1.9 V, with good endurance and retention properties. As the bias voltage increases further beyond 4 V under a forward bias, a forming process occurs resulting in irreversible RS mode transformation from bipolar to unipolar mode. This switching mode transformation is a direct consequence of thermally activated Ti out-diffusion from a Ti adhesion layer. Transition metal Ti effectively out-diffuses through the loose Pt electrode layer at high substrate temperatures, leading to the unintended formation of a thin titanium oxide (TiOx where x < 2) layer between the Pt electrode and the SZO:Cr layer as well as additional Ti atoms in the SZO:Cr layer. Cross-sectional scanning electron microscopy, transmission electron microscopy and Auger electron spectroscopy depth-profile measurements provided apparent evidence of the Ti out-diffusion phenomenon. We propose that the out-diffusion-induced additional Ti atoms in the SZO:Cr layer contributes to the creation of the metallic filamentary channels. PMID:25483325

  16. SIMULTANEOUS B'V'R' MONITORING OF BL LACERTAE OBJECT S5 0716+714 AND DETECTION OF INTER-BAND TIME DELAY

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

    Wu Jianghua; He Xiangtao; Boettcher, Markus

    We present the results of our optical monitoring of the BL Lac object S5 0716+714 over seven nights in 2006 December. The monitoring was carried out simultaneously at three optical wavelengths with a novel photometric system. The object did not show large-amplitude internight variations during this period. Intranight variations were observed on four nights and probably on one more. Strong bluer-when-brighter chromatism was detected on both intranight and internight timescales. The intranight variation amplitude decreases in the wavelength sequence of B', R', and V'. Cross-correlation analyses revealed that the variability at the B' and V' bands leads that at themore » R' band by about 30 minutes on one night.« less

  17. Morphology and Performance of 5Cr5MoV Casting Die Steel in the Process of Surfacing

    NASA Astrophysics Data System (ADS)

    Song, Yulai; Kong, Xiangrui; Yang, Pengcong; Fu, Hongde; Wang, Xuezhu

    2017-12-01

    To investigate the microstructures and mechanical properties of the deposited metal on surface of die steel, two layer of weld-seam were prepared on the surface of 5Cr5MoV die steel by arc surfacing. The surface microstructures and microhardness were characterized by scanning electron microscopy, energy dispersive spectrometer and Vickers microhardness tester, respectively. The effect of load on the abrasion resistance and wear mechanism of the base metal and surfacing metal was studied by pin-on-disk tribometer. The results showed that martensite and retained austenite exist in weld-seam, both of them grow up in the form of dendrites and equiaxed grains and microhardness reach 774.2HV. The microstructures of the quenching zone mainly consist of martensite and retained austenite, while tempered martensite is the dominant phase in partial quenching zone. The abrasion resistance of the surfacing metal is superior to the base metal based on the results of wear test. The wear rates of surfacing metal and base metal raise with the increase of load. The wear rates of base metal raise extremely when the load reach 210N. Both of two kinds of materials have the similar wear mechanism, namely, abrasive wear at low load, oxidative wear and adhesive wear at high load.

  18. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  19. Effect of Ge-GeO2 co-doping on non-ohmic behaviour of TiO2-V2O5-Y2O3 varistor ceramics

    NASA Astrophysics Data System (ADS)

    Kunyong, Kang; Guoyou, Gan; Jikang, Yan; Jianhong, Yi; Jiamin, Zhang; Jinghong, Du; Wenchao, Zhao; Xuequan, Rong

    2015-07-01

    An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2-V2O5-Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 mol%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO2 makes the highest α value (α = 12.8), the lowest breakdown voltage V1mA (V1mA = 15.8 V/mm) and the highest grain boundary barrier ΦB (ΦB = 1.48 eV), which is remarkably superior to the TiO2-V2O5-Y2O3 varistor ceramics undoped with Ge and GeO2 and mono-doped with Ge or GeO2. The TiO2-V2O5-Y2O3-Ge-GeO2 ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties. Project supported by the National Natural Science Foundation of China (Nos. 51262017, 51362017).

  20. Stable Ferroelectric Behavior of Nb-Modified Bi0.5K0.5TiO3-Bi(Mg0.5Ti0.5)O3 Lead-Free Relaxor Ferroelectric Ceramics

    NASA Astrophysics Data System (ADS)

    Zaman, Arif; Malik, Rizwan Ahmed; Maqbool, Adnan; Hussain, Ali; Ahmed, Tanveer; Song, Tae Kwon; Kim, Won-Jeong; Kim, Myong-Ho

    2018-03-01

    Crystal structure, dielectric, ferroelectric, piezoelectric, and electric field-induced strain properties of lead-free Nb-modified 0.96Bi0.5K0.5TiO3-0.04Bi(Mg0.5Ti0.5)O3 (BKT-BMT) piezoelectric ceramics were investigated. Crystal structure analysis showed a gradual phase transition from tetragonal to pseudocubic phase with increasing Nb content. The optimal piezoelectric property of small-signal d 33 was enhanced up to ˜ 68 pC/N with a lower coercive field ( E c) of ˜ 22 kV/cm and an improved remnant polarization ( P r) of ˜ 13 μC/cm2 for x = 0.020. A relaxor-like behavior with a frequency-dependent Curie temperature T m was observed, and a high T m around 320°C was obtained in the investigated system. This study suggests that the ferroelectric properties of BKT-BMT was significantly improved by means of Nb substitution. The possible shift of depolarization temperature T d toward high temperature T m may have triggered the spontaneous relaxor to ferroelectric phase transition with long-range ferroelectric order without any traces of a nonergodic relaxor state in contradiction with Bi0.5Na0.5TiO3-based systems. The possible enhancement in ferroelectric and piezoelectric properties near the critical composition x = 0.020 may be attributed to the increased anharmonicity of lattice vibrations which may facilitate the observed phase transition from a low-symmetry tetragonal to a high-symmetry cubic phase with a decrease in the lattice anisotropy of an undoped sample. This highly flexible (at a unit cell level) narrow compositional range triggers the enhancement of d 33 and P r values.

  1. Surface structure of MgO underlayer with Ti diffusion for (002) oriented L10 FePt-based heat assisted magnetic recording media

    NASA Astrophysics Data System (ADS)

    Hinata, Sintaro; Jo, Shin; Saito, Shin

    2018-05-01

    Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm)/Cr80Mn20 (0-30 nm)/Cr50Ti50 (0-50 nm)/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW) on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

  2. Synthesis of Cr3+-doped TiO2 nanoparticles: characterization and evaluation of their visible photocatalytic performance and stability.

    PubMed

    Mendiola-Alvarez, Sandra Yadira; Guzmán-Mar, Jorge Luis; Turnes-Palomino, Gemma; Maya-Alejandro, Fernando; Caballero-Quintero, Adolfo; Hernández-Ramírez, Aracely; Hinojosa-Reyes, Laura

    2017-09-28

    Cr 3+ -doped TiO 2 nanoparticles (Ti-Cr) were synthesized by microwave-assisted sol-gel method. The Ti-Cr catalyst was characterized by X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, N 2 adsorption-desorption analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy (XPS) and zetametry. The anatase mesoporous Ti-Cr material exhibited a specific surface area of 54.5 m 2 /g. XPS analysis confirmed the proper substitution of Ti 4+ cations by Cr 3+ cations in the TiO 2 matrix. The particle size was of average size of 17 nm for the undoped TiO 2 but only 9.5 nm for Ti-Cr. The Cr atoms promoted the formation of hydroxyl radicals and modified the surface adsorptive properties of TiO 2 due to the increase in surface acidity of the material. The photocatalytic evaluation demonstrated that the Ti-Cr catalyst completely degraded (4-chloro-2-methylphenoxy) acetic acid under visible light irradiation, while undoped TiO 2 and P25 allowed 45.7% and 31.1%, respectively. The rate of degradation remained 52% after three cycles of catalyst reuse. The higher visible light photocatalytic activity of Ti-Cr was attributed to the beneficial effect of Cr 3+ ions on the TiO 2 surface creating defects within the TiO 2 crystal lattice, which can act as charge-trapping sites, reducing the electron-hole recombination process.

  3. The strain induced band gap modulation from narrow gap semiconductor to half-metal on Ti{sub 2}CrGe: A first principles study

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

    Li, Jia, E-mail: jiali@hebut.edu.cn; Research Institute for Energy Equipment Materials, Hebei University of Technology, Tianjin 300401; Zhang, Zhidong

    The Heusler alloy Ti{sub 2}CrGe is a stable L2{sub 1} phase with antiferromagnetic ordering. With band-gap energy (∼ 0.18 eV) obtained from a first-principles calculation, it belongs to the group of narrow band gap semiconductor. The band-gap energy decreases with increasing lattice compression and disappears until a strain of −5%; moreover, gap contraction only occurs in the spin-down states, leading to half-metallic character at the −5% strain. The Ti{sub 1}, Ti{sub 2}, and Cr moments all exhibit linear changes in behavior within strains of −5%– +5%. Nevertheless, the total zero moment is robust for these strains. The imaginary part ofmore » the dielectric function for both up and down spin states shows a clear onset energy, indicating a corresponding electronic gap for the two spin channels.« less

  4. Optimization of TiNP/Ti Content for Si3N4/42CrMo Joints Brazed With Ag-Cu-Ti+TiNP Composite Filler

    NASA Astrophysics Data System (ADS)

    Wang, Tianpeng; Zhang, Jie; Liu, Chunfeng

    The Si3N4 ceramic was brazed to 42CrMo steel by using TiN particles modified braze, and the proportion of TiNp reinforcement and active element Ti was optimized to improve the joint strength. The brazed joints were examined by means of SEM. and EDS investigations. Microstructural examination showed that TiN+Ti5Si3 reaction layer was adjacent to Si3N4, whereas TiC was formed in 42CrMo/filler reaction layer. The Ag-Cu-Ti brazing alloy showed intimate bonding with TiNp and Cu-Ti intermetallics precipitated in the joint. The strength tests demonstrated that the mechanical properties of joints increased and then decreased by increasing the TiNp content when a low Ti content (6wt.%) was supplied. When the Ti content (>6wt.%) was offered sufficiently, the joint strength decreased firstly and then stayed stable with increasing the TiNp content. The maximum four-point bending strength (221 MPa) was obtained when the contents of TiNp and Ti were 10vol.% and 6wt.%, respectively.

  5. Electrochemical behavior of 45S5 bioactive ceramic coating on Ti6Al4V alloy for dental applications

    NASA Astrophysics Data System (ADS)

    Machado López, M. M.; Espitia Cabrera, M. I.; Faure, J.; Contreras García, M. E.

    2016-04-01

    Titanium and its alloys are widely used as implant materials because of their mechanical properties and non-toxic behavior. Unfortunately, they are not bioinert, which means that they can release ions and can only fix the bone by mechanical anchorage, this can lead to the encapsulation of dense fibrous tissue in the body. The bone fixation is required in clinical conditions treated by orthopedic and dental medicine. The proposal is to coat metallic implants with bioactive materials to establish good interfacial bonds between the metal substrate and bone by increasing bioactivity. Bioactive glasses, ceramics specifically 45 S5 Bioglass, have drawn attention as a serious functional biomaterial because osseointegration capacity. The EPD method of bioglass gel precursor was proposed in the present work as a new method to obtain 45S5/Ti6A14V for dental applications. The coatings, were thermally treated at 700 and 800°C and presented the 45 S5 bioglass characteristic phases showing morphology and uniformity with no defects, quantification percentages by EDS of Si, Ca, Na, P and O elements in the coating scratched powders, showed a good proportional relationship demonstrating the obtention of the 45S5 bioglass. The corrosion tests were carried out in Hank's solution. By Tafel extrapolation, Ti6Al4V alloy showed good corrosion resistance in Hank's solution media, by the formation of a passivation layer on the metal surface, however, in the system 45S5/Ti6Al4V there was an increase in the corrosion resistance; icon-, Ecorr and corrosion rate decreased, the mass loss and the rate of release of ions, were lower in this system than in the titanium alloy without coating.

  6. Cr-doped TiSe 2 - A layered dichalcogenide spin glass

    DOE PAGES

    Luo, Huixia; Tao, Jing; Krizan, Jason W.; ...

    2015-09-17

    We report the magnetic characterization of the Cr-doped layered dichalcogenide TiSe 2. The temperature dependent magnetic susceptibilities are typical of those seen in geometrically frustrated insulating antiferromagnets. The Cr moment is close to the spin-only value, and the Curie–Weiss temperatures (θ cw) are between –90 and –230 K. Freezing of the spin system, which is glassy, characterized by peaks in the ac and dc susceptibility and specific heat, does not occur until below T/θ cw = 0.05. The CDW transition seen in the resistivity for pure TiSe 2 is still present for 3% Cr substitution but is absent by 10%more » substitution, above which the materials are metallic and p-type. Structural refinements, magnetic characterization, and chemical considerations indicate that the materials are of the type Ti 1–xCr xSe 2-x/2 for 0 ≤ x ≤ 0.6.« less

  7. Temperature field simulation on Ti6Al4V and Inconel718 heated by continuous infrared laser

    NASA Astrophysics Data System (ADS)

    Wang, Yanshen; Zhang, Zheng; Feng, Weiwei; Wang, Bo; Gai, Yuxian

    2014-08-01

    Laser assisted machining technology can heat and soften metals, which can be used for improving the machinability of superalloys such as Ti6Al4V and Inconel718. Researches on temperature field simulation of Ti6Al4V and Inconel718 are conducted in this paper. A thermal differential equation is established based on Fourier's law and energy conservation law. Then, a model using ABAQUS for simulating heat transfer process is brought out, which is then experimentally validated. Using the simulation model, detailed investigations on temperature field simulation are carried out in Ti6Al4V and Inconel718. According to simulation, surface temperature of the two superalloys eventually reaches their peak values, and the peak temperature of Ti6Al4V is much higher than that of Inconel718. To further investigate temperature heated by laser, laser parameters such as power, scanning velocity, laser spot radius and inclination angle are set to be variables separately for simulation. Simulation results show that laser power and laser spot radius are predominant factors in heating process compared with the influence of scanning velocity and inclination angle. Simulations in this paper provide valuable references for parameter optimization in the following laser heating experiments, which plays an important role in laser assisted machining.

  8. Modification of Pseudobrookite Fe2-XMnxTiO5 with Solid State Reaction Method using a Mechanical Milling

    NASA Astrophysics Data System (ADS)

    Sarwanto, Y.; Adi, W. A.

    2017-05-01

    Modification of pseudobrookite Fe2-xMnxTiO5 with solid state reaction method using a mechanical milling has been synthesized. Raw materials used to prepare these samples were Fe2O3, MnCO3, and TiO2. Fe2O3 and TiO2 powders (ratio of 1:1) were mixed with MnCO3 powder at various composition of x = 0; 0.1; 0.2; 0.3; 0.4; 0.5; and 1, which each composition was added with 50 ml ethanol and then milled for 5 hours through high energy milling, after that sintered at 1000 °C for 5 hours by using box furnace. The phases of Fe2-xMnxTiO5 were measured by using X-ray diffraction (XRD) and then identified by using Match program. The crystal structure was analyzed by using the program of General Structure Analysis System (GSAS). Quality fitting of Rwp and χ2 (chi-squared) are relatively good because based on the curve of normalized error distribution looks just left background and its normal probability plot shows the value of comparable between observation and expectation. The refinement analyses of X-ray diffraction patterns showed that the samples formed single phase for x ≤ 0.3. However, the samples of x > 0.3 were multi-phases. The single phase of sample had composition of pseudobrookite Fe2TiO5 with orthorhombic structure, space group of C m c m (63), the lattice parameters of a = 3.7390 Å, b = 9.7790 Å, and c = 9.9780 Å, α = β = γ = 90°, V = 364.83 Å3, and ρ = 4.360 g.cm-3. Meanwhile, the other phase analysis for the composition of x > 0.3 is bixbyite (FeMnO3). The bixbyite has a cubic structure, under the space group of I a - 3 (206), the lattice parameters of a = b = c = 9.40 Å, α = β = γ = 90°, V = 830.58 Å3, and ρ = 5.078 g.cm-3.

  9. Preparation of La 0.75Sr 0.25Cr 0.5Mn 0.5O 3- δ fine powders by carbonate coprecipitation for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Ha, Sang Bu; Cho, Pyeong-Seok; Cho, Yoon Ho; Lee, Dokyol; Lee, Jong-Heun

    A range of La 0.75Sr 0.25Cr 0.5Mn 0.5O 3- δ (LSCM) powders is prepared by the carbonate coprecipitation method for use as anodes in solid oxide fuel cells. The supersaturation ratio (R = [(NH 4) 2CO 3]/([La 3+] + [Sr 2+] + [Cr 3+] + [Mn 2+])) during the coprecipitation determines the relative compositions of La, Sr, Cr, and Mn. The composition of the precursor approaches the stoichiometric one at the supersaturation range of 4 ≤ R ≤ 12.5, whereas Sr and Mn components are deficient at R < 4 and excessive at R = 25. The fine and phase-pure LSCM powders are prepared by heat treatment at very low temperature (1000 °C) at R = 7.5 and 12.5. By contrast, the solid-state reaction requires a higher heat-treatment temperature (1400 °C). The catalytic activity of the LSCM electrodes is enhanced by using carbonate-derived powders to manipulate the electrode microstructures.

  10. The influence of crystal structure on ion-irradiation tolerance in the Sm(x)Yb(2-x)TiO5 series

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

    Aughterson, R. D.; Lumpkin, G. R.; de los Reyes, M.

    2016-04-01

    his ion-irradiation study covers the four major crystal structure types in the Ln(2)TiO(5) series (Ln = lanthanide), namely orthorhombic Pnma, hexagonal P63/mmc, cubic (pyrochlore-like) Fd-3m and cubic (fluorite-like) Fm-3m. This is the first systematic examination of the complete Ln(2)TiO(5) crystal system and the first reported examination of the hexagonal structure. A series of samples, based on the stoichiometry Sm(x)Yb(2-x)TiO5 (where x = 2, 1.4, 1, 0.6, and 0) have been irradiated using 1 MeV Kr2+ ions and characterised in-situ using a transmission electron microscope. Two quantities are used to define ion-irradiation tolerance: critical dose of amorphisation (D-c), which is themore » irradiating ion dose required for a crystalline to amorphous transition, and the critical temperature (T-c), above which the sample cannot be rendered amorphous by ion irradiation. The structure type plus elements of bonding are correlated to ion-irradiation tolerance. The cubic phases, Yb2TiO5 and Sm0.6Yb1.4TiO5, were found to be the most radiation tolerant, with Tc values of 479 and 697 K respectively. The improved radiation tolerance with a change in symmetry to cubic is consistent with previous studies of similar compounds.« less

  11. Toxic effect of Cr(VI) in presence of n-TiO2 and n-Al2O3 particles towards freshwater microalgae.

    PubMed

    Dalai, Swayamprava; Pakrashi, Sunandan; Bhuvaneshwari, M; Iswarya, V; Chandrasekaran, N; Mukherjee, Amitava

    2014-01-01

    The reactivity and toxicity of the soluble toxicants in the presence of the engineered nanomaterials is not well explored. In this study, the probable effects of TiO2 and Al2O3 nanoparticles (n-TiO2, n-Al2O3) on the toxicity of Cr(VI) were assessed with the dominant freshwater algae, Scenedesmus obliquus, in a low range of exposure concentrations (0.05, 0.5 and 1μg/mL). In the presence of 0.05μg/mL n-TiO2, the toxicity of Cr(VI) decreased considerably, which was presumably due to the Cr(VI) adsorption on the nanoparticle surface leading to its aggregation and precipitation. The elevated n-TiO2 concentrations (0.5 and 1μg/mL) did not significantly influence Cr(VI) bio-availability, and a dose dependent toxicity of Cr(VI) was observed. On the other hand, n-Al2O3 did not have any significant effect on the Cr(VI) toxicity. The microscopic observations presented additional information on the morphological changes of the algal cells in the presence of the binary toxicants. The generation of reactive oxygen species (ROS) suggested contribution of oxidative stress on toxicity and LDH release confirmed membrane permeability of algal cells upon stress. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Effect of irradiation temperature and strain rate on the mechanical properties of V-4Cr-4Ti irradiated to low doses in fission reactors

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

    Zinkle, S.J.; Snead, L.L.; Rowcliffe, A.F.

    Tensile tests performed on irradiated V-(3-6%)Cr-(3-6%)Ti alloys indicate that pronounced hardening and loss of strain hardening capacity occurs for doses of 0.1--20 dpa at irradiation temperatures below {approximately}330 C. The amount of radiation hardening decreases rapidly for irradiation temperatures above 400 C, with a concomitant increase in strain hardening capacity. Low-dose (0.1--0.5 dpa) irradiation shifts the dynamic strain aging regime to higher temperatures and lower strain rates compared to unirradiated specimens. Very low fracture toughness values were observed in miniature disk compact specimens irradiated at 200--320 C to {approximately}1.5--15 dpa and tested at 200 C.

  13. High temperature gas nitriding and tempering in 17Cr-1Ni-0.5C-0.4V steel

    NASA Astrophysics Data System (ADS)

    Kong, J. H.; Lee, D. J.; On, H. Y.; Park, S. J.; Kim, S. K.; Kang, C. Y.; Sung, J. H.; Lee, H. W.

    2010-12-01

    High temperature gas nitriding (HTGN) at 1050 °C and tempering of a 17Cr-1Ni-0.5C-0.4V (CNV) steel were experimentally investigated. The phases appearing in the surface layer of the HTGN-treated steel were martensite and austenite with mostly Cr2N precipitates that were formed by permeated nitrogen, and a small amount of Cr23C6 and VN precipitates. The reverse migration of carbon hindered the diffusion of nitrogen when nitrogen permeated from the surface to the interior, which resulted in the accumulation of nitrogen on the outermost surface. The strong affinity between nitrogen and chromium atoms induced the diffusion of chromium from the interior to the surface, leading to the substitution of Cr23C6 for Cr2N. After tempering the HTGN-treated steel at 500 °C, the dense precipitates of Cr2N and the increased martensite phase in the surface layer led to secondary hardening, which increased the hardness value up to 901 Hv.

  14. Investigation on magnetoelectric behavior of (80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)-CoFe2O4 particulate composites

    NASA Astrophysics Data System (ADS)

    Liu, Sheng; Yan, Shuoqing; Yao, Lingling; He, Jun; He, Longhui; Hu, Zhaowen; Huang, Shengxiang; Deng, Lianwen

    2017-12-01

    Particulate magnetoelectric (ME) ceramics constituted by (1-x)(80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)-xCoFe2O4 [(1-x)BNKT-xCFO] (x = 0, 0.1, 0.2, 0.3, 0.4 and 1.0) were synthesized by an powder-in-sol precursor hybrid processing method and their structure, magnetic, ferroelectric, magnetodielectric (MD) and ME properties have been investigated. Results showed that the ceramics consisted of only two chemically separated phases and had homogeneous microstructure. The introduction of CFO into BNKT matrix led to the weakening of ferroelectric and dielectric properties whereas the strengthening magnetic and MD properties. The observation of the MD effect revealed the evidence of the strain-induced ME coupling and the MD value is well scaled with M2. A maximum value of ME output of 25.07 mV/cm·Oe was achieved for the 0.7BNKT-0.3CFO composite. The improved ME response together with the linear MD effect makes the ceramics promise for use in magnetic field controllable devices or magneto-electric transducers.

  15. Densification of PZT Ceramics with V2O5 Additive.

    DTIC Science & Technology

    1979-01-01

    Additions of V2O5 from 0.1 to 8.0 w/o to a coprecipitated Pb(Zr.53 Ti.47) O3 ceramic promoted rapid densification below 1025 C, eliminating the need...for PbO atmosphere control. Dielectric properties were found to be dependent on the amount of V2O5 added and on the microstructure developed, but were...comparable to reported values for this PZT composition for additions of V2O5 or = 1.5 W/O. The indicated densification mechanism is one of activated sintering catalyzed by generation of oxygen defects on decomposition of the V2O5 .

  16. Comparison of mechanical behavior of TiN, TiNC, CrN/TiNC, TiN/TiNC films on 9Cr18 steel by PVD

    NASA Astrophysics Data System (ADS)

    Feng, Xingguo; Zhang, Yanshuai; Hu, Hanjun; Zheng, Yugang; Zhang, Kaifeng; Zhou, Hui

    2017-11-01

    TiN, TiNC, CrN/TiNC and TiN/TiNC films were deposited on 9Cr18 steel using magnetron sputtering technique. The morphology, composition, chemical state and crystalline structure of the films were observed and analyzed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Hardness and adhesion force were tested by nanoindentation and scratch tester, respectively. The friction and wear behavior of TiN, TiNC, CrN/TiNC and TiN/TiNC films sliding against GCr15 balls were investigated and compared synthetically using ball-on-disk tribometer. It was found that Tisbnd N, Tisbnd C, Tisbnd Nsbnd C and Csbnd C bonds were formed. The TiN/TiNC film was composed of TiN, TiC and TiNC phases. Hardness and adhesion force results indicated that although the TiN film possessed the highest hardness, its adhesion force was lowest among all the films. Tribological test results showed that the friction coefficient of TiN/TiNC was much lower than that of TiN and the wear rate decreases remarkably from 2.3 × 10-15 m3/Nm to 7.1 × 10-16 m3/Nm, which indicated the TiN/TiNC film has better wear resistance.

  17. Hematite enhances the removal of Cr(VI) by Bacillus subtilis BSn5 from aquatic environment.

    PubMed

    Ma, Shuai; Song, Chang-Shun; Chen, Yuefang; Wang, Fei; Chen, Hui-Lun

    2018-06-05

    In the present study, we investigated the removal of Cr(VI) and the associated bacterial activity in the systems containing Bacillus subtilis BSn5 (B. subtilis BSn5) and hematite. The microcalorimetry was used to study the effect of hematite on the normal physiological functions of B. subtilis BSn5 towards the removal of Cr(VI) for the first time. The results of the heat flux and the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that hematite does not affect the normal physiological functions of B. subtilis BSn5, and can help the strains maintain their activity in the presence of Cr(VI). More importantly, the relative capacity and intensity of Cr(VI) and total Cr removal by B. subtilis BSn5 in the presence of hematite were higher than that in the absence of hematite. The enhancement effect could be associated with their mineral adsorption, biosorption, Fe(II) reduction, bioreduction and immobilization functions. This study demonstrates the possibility of reducing the toxicity of Cr(VI) and enhancing the Cr(VI) removal efficiency in contaminated environments using a combination of hematite and B. subtilis BSn5. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Laser Cladding of TiAl Intermetallic Alloy on Ti6Al4V -Process Optimization and Properties

    NASA Astrophysics Data System (ADS)

    Cárcel, B.; Serrano, A.; Zambrano, J.; Amigó, V.; Cárcel, A. C.

    In order to improve Ti6Al4V high-temperature resistance and its tribological properties, the deposition of TiAl intermetallic (Ti-48Al-2Cr-2Nb) coating on a Ti6Al4V substrate by coaxial laser cladding has been investigated. Laser cladding by powder injection is an emerging laser material processing technique that allows the deposition of thick protective coatings on substrates,using a high power laser beam as heat source. Laser cladding is a multiple-parameter-dependent process. The main process parameters involved (laser power, powder feeding rate, scanning speed and preheating temperature) has been optimized. The microstructure and geometrical quantities (clad area and dilution) of the coating was characterized by optical microscopy and scanning electron microscopy (SEM). In addition the cooling rate of the clad during the process was measured by a dual-color pyrometer. This result has been related to defectology and mechanical coating properties.

  19. The crystal structure of the mixed-layer Aurivillius phase Bi 5Ti 1.5W 1.5O 15

    NASA Astrophysics Data System (ADS)

    Tellier, J.; Boullay, Ph.; Créon, N.; Mercurio, D.

    2005-09-01

    The crystal structure of the 1+2 mixed-layer Aurivillius phase Bi 5Ti 1.5W 1.5O 15 (SG I2cm n o 46: -cba, Z=4, a=5.4092(3) Å, b=5.3843(3) Å and c=41.529(3) Å) consisting of the ordered intergrowth of one and two octahedra thick perovskite-type blocks separated by [Bi 2O 2] 2+ slabs is reported. Supported by an electron diffraction investigation and, using the Rietveld analysis, it is shown that this compound should be described using a I-centering lattice in agreement with the generalised structural model of the Aurivillius type compounds recently presented by the authors. The structure of this Bi 5Ti 1.5W 1.5O 15 phase is analyzed in comparison with the related simple members (Bi 2WO 6 and Bi 3Ti 1.5W 0.5O 9). The crystal structure of Bi 3Ti 1.5W 0.5O 9 is also reported.

  20. Heating Effect on Manufacturing Li4Ti5O12 Electrode Sheet with PTFE Binder on Battery Cell Performance

    NASA Astrophysics Data System (ADS)

    Priyono, S.; Lubis, B. M.; Humaidi, S.; Prihandoko, B.

    2018-05-01

    The synthesis of Li4Ti5O12 (LTO) and study of the heating effect on the manufacturing process of LTO sheet on the electrochemical performance have been investigated. LTO anode material composed with LiOH.H2O, TiO2 as raw materials were synthesized by the solid-state process. All raw materials were stoichiometrically mixed and milled with a planetary ball mill for 4 h to become the precursor of LTO. The precursor was characterized by Simultaneous Thermal Analyzer (STA) to determine sintering temperature. The STA analysis revealed that the minimum temperature to sinter the precursor was 600 °C. The precursor was sintered by using high-temperature furnace at 900 °C for 2 h in air atmosphere. The final product was ground and sieved with a screen to get finer and more homogenous particles. The final product was characterized by X-ray Diffraction (XRD) to determined crystal structure and phases. LTO sheet was prepared by mixing LTO powders with PTFE and AB in ratio 85:10:5 wt% by varrying heating process with 40 °C, 50 °C and 70 °C to become slurry. The slurry was coated on Cu foil with doctor blade method and dried at 80 °C for 1 h. LTO sheet was characterized by FTIR to analyze functional groups. LTO sheet was cut into circular discs with 16 mm in diameter. LTO sheet was arranged with a separator, metallic lithium and electrolyte become coin cell in a glove box. Automatic battery cycler was used to measure electrochemical performance and specific capacity of the cell. From the XRD analysis showed that single phase of LTO phase with a cubic crystal structure is formed. FTIR testing showed that there are stretching vibrations of Ti-O and H-F from tetrahedral TiO6 and PTFE respectively. Increasing temperature on LTO sheet manufacturing doesn’t change the structure of LTO. Cyclic voltammetry analysis showed that sample with heating of 40 °C showed better redox process than others. Charge-discharge test also showed that sample with heating of 40 °C has higher

  1. Structure and colossal dielectric permittivity of Ca2TiCrO6 ceramics

    NASA Astrophysics Data System (ADS)

    Yan-Qing, Tan; Meng, Yan; Yong-Mei, Hao

    2013-01-01

    A colossal permittivity ceramic material, Ca2TiCrO6, was successfully synthesized by the conventional solid-state reaction, and was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray photoemission spectroscopy (XPS) and x-ray diffraction (XRD). Rietveld refinement of XRD data indicated that the material crystallized in orthorhombic structure with space group pbnm. SEM displayed Ca2TiCrO6 ceramic grains packed uniformly with the size range 5-20 µm. XPS analyses indicated that elemental chromium and titanium of the material were in mixed valence. The corresponding dielectric property was tested in the frequency range 1 kHz-1 MHz and the temperature range 213-453 K, and the ceramics exhibited a relaxation-like dielectric behaviour. Importantly, the permittivity of Ca2TiCrO6 could reach 80 000 at 298 K (100 Hz) and was maintained at 40 000 up to 398 K at 1 MHz, which could be attributed to the ion disorder and mixed valence of Cr3+/Cr6+ and Ti3+/Ti4+.

  2. 44 CFR 63.5 - Coverage for contents removal.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Coverage for contents removal. 63.5 Section 63.5 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT... OF SECTION 1306(c) OF THE NATIONAL FLOOD INSURANCE ACT OF 1968 General § 63.5 Coverage for contents...

  3. 44 CFR 63.5 - Coverage for contents removal.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 44 Emergency Management and Assistance 1 2011-10-01 2011-10-01 false Coverage for contents removal. 63.5 Section 63.5 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT... OF SECTION 1306(c) OF THE NATIONAL FLOOD INSURANCE ACT OF 1968 General § 63.5 Coverage for contents...

  4. [Effect of different heat treatment on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys].

    PubMed

    Liang, Rui-ying; Li, Chang-yi; Han, Ya-jing; Hu, Xin; Zhang, Lian-yun

    2008-11-01

    To evaluate the effect of heat treatment and porcelain-fused-to-metal (PFM) processing on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys. Samples of CoCr-NiCr dissimilar alloys with 0.5 mm thickness were laser-welded single-side under the setting parameters of 280 V, 10 ms pulse duration. After being welded, samples were randomly assigned to three groups, 10 each. Group1 and 2 received heat treatment and PFM processing, respectively. Group 3 was control group without any treatment. Tensile strength, microstructure and element distribution of samples in the three groups were tested and observed using tensile test, metallographic examinations, scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) analysis. After heat treatment and PFM processing, tensile strength of the samples were (537.15 +/- 43.91) MPa and (534.58 +/- 48.47) MPa respectively, and elongation rates in Group 1 and 2 were (7.65 +/- 0.73)% and (7.40 +/- 0.45)%. Ductile structure can be found on tensile fracture surface of samples and it was more obvious in heat treatment group than in PFM group. The results of EDS analysis indicated that certain CoCr alloy diffused towards fusion zone and NiCr side after heat treatment and PFM processing. Compared with PFM processing group, the diffusion in the heat treatment group was more obvious. Heat treatment and PFM processing can improve the mechanical properties and microstructure of welded CoCr-NiCr dissimilar alloy to a certain degree. The improvements are more obvious with heat treatment than with porcelain treatment.

  5. Rapid Repairs: Surface Preparation of Ti-3 Al-2.5V Alloy Tubes by Fiber Laser and Welding

    DTIC Science & Technology

    2008-11-01

    processing of titanium 6Al - 4V alloy for potential aerospace component cleaning application, Appl Surf Sci 2005;247:623-630. [11] Turner MW, Crouse...Debroy T, Heat transfer and fluid flow during keyhole mode laser welding of tantalum, Ti- 6Al - 4V , 304 Stainless Steel and Vanadium, J Phy D : Appl Phy...14Titanium alloys are used extensively in aerospace applications mainly due to their superior strength to weight ratio. Different grades of titanium

  6. A urea biosensor based on pH-sensitive Sm2TiO5 electrolyte-insulator-semiconductor.

    PubMed

    Pan, Tung-Ming; Huang, Ming-De; Lin, Wan-Ying; Wu, Min-Hsien

    2010-06-11

    A urea biosensor based on pH-sensitive Sm(2)TiO(5) electrolyte-insulator-semiconductor (EIS) has been described. We used X-ray diffraction, Auger electron spectroscopy, and atomic force microscopy to investigate the structural and morphological features of high-k Sm(2)TiO(5) sensing membranes that had been subjected to annealing at different temperatures. The EIS device incorporating a high-k Sm(2)TiO(5) sensing film that had been annealed at 900 degrees C exhibited good sensing characteristics, including a high sensitivity of 60.5 mV/pH (in solutions from pH 2 to 12), a small hysteresis voltage of 2.72 mV (in the pH loop 7-->4-->7-->10-->7), and a low drift rate of 1.15 mV h(-1) (in the buffer solution at pH 7). The Sm(2)TiO(5) EIS device also showed a high selective response towards H(+). This improvement can be attributed to the small number of crystal defects and the large surface roughness. In addition, the urea biosensor based on pH-sensitive EIS incorporating a Sm(2)TiO(5) sensing membrane annealed at 900 degrees C allowed the potentiometric analysis of urea, at concentrations ranging from 0.1 to 32 mM, with a sensitivity of 72.85 mV/purea. Copyright 2010 Elsevier B.V. All rights reserved.

  7. 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.

  8. Optical, structural, and chemical properties of CR-39 implanted with 5.2 MeV doubly charged carbon ions

    NASA Astrophysics Data System (ADS)

    Ali, Dilawar; Butt, M. Z.; Ishtiaq, Mohsin; Waqas Khaliq, M.; Bashir, Farooq

    2016-11-01

    Poly-allyl-diglycol-carbonate (CR-39) specimens were irradiated with 5.2 MeV doubly charged carbon ions using Pelletron accelerator. Ion dose was varied from 5 × 1013 to 5 × 1015 ions cm-2. Optical, structural, and chemical properties were investigated by UV-vis spectroscopy, x-ray diffractometer, and FTIR/Raman spectroscopy, respectively. It was found that optical absorption increases with increasing ion dose. Absorption edge shifts from UV region to visible region. The measured opacity values of pristine and ion implanted CR-39 range from 0.0519 to 4.7959 mm-1 following an exponential growth (9141%) with the increase in ion dose. The values of direct and indirect band gap energy decrease exponentially with an increase in ion dose by 59% and 71%, respectively. However, average refractive index in the visible region increases from 1.443 to 2.864 with an increase in ion dose, by 98%. A linear relation between band gap energy and crystallite size was observed. Both the number of carbon atoms in conjugation length and the number of carbon atoms per cluster increase linearly with the increase in ion dose. FTIR spectra showed that on C+2 ions irradiation, the intensity of all bands decreases gradually without appearance of any new band, indicating degradation of polymer after irradiation. Raman spectra revealed that the density of -CH2- group decreases on C+2 ions irradiation. However, the structure of CR-39 is completely destroyed on irradiation with ion dose 1 × 1015 and 5 × 1015 ions cm-2.

  9. The 3CR Chandra Snapshot Survey: Extragalactic Radio Sources with Redshifts between 1 and 1.5

    NASA Astrophysics Data System (ADS)

    Stuardi, C.; Missaglia, V.; Massaro, F.; Ricci, F.; Liuzzo, E.; Paggi, A.; Kraft, R. P.; Tremblay, G. R.; Baum, S. A.; O’Dea, C. P.; Wilkes, B. J.; Kuraszkiewicz, J.; Forman, W. R.; Harris, D. E.

    2018-04-01

    The aim of this paper is to present an analysis of newly acquired X-ray observations of 16 extragalactic radio sources listed in the Third Cambridge Revised (3CR) catalog and not previously observed by Chandra. Observations were performed during Chandra Cycle 17, extending X-ray coverage for the 3CR extragalactic catalog up to z = 1.5. Among the 16 targets, two lie at z < 0.5 (3CR 27 at z = 0.184 and 3CR 69 at z = 0.458) all of the remaining 14 have redshifts between 1.0 and 1.5. In the current sample, there are three compact steep spectrum (CSS) sources, three quasars, and an FR I radio galaxy, while the other nine are FR II radio galaxies. All radio sources have an X-ray counterpart. We measured nuclear X-ray fluxes as well as X-ray emission associated with radio jet knots, hotspots, or lobes in three energy bands: soft (0.5–1 keV), medium (1–2 keV), and hard (2–7 keV). We also performed standard X-ray spectral analysis for the four brightest nuclei. We discovered X-ray emission associated with the radio lobe of 3CR 124, a hotspot of the quasar 3CR 220.2, another hotspot of the radio galaxy 3CR 238, and the jet knot of 3CR 297. We also detected extended X-ray emission around the nuclear region of 3CR 124 and 3CR 297 on scales of several tens of kiloparsecs. Finally, we present an update on the X-ray observations performed with Chandra and XMM-Newton on the entire 3CR extragalactic catalog.

  10. Pressure-induced Structural Transformations in LanthanideTitanates: La2TiO5 and Nd2TiO5

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

    F Zhang; J Wang; M Lang

    The structure of orthorhombic rare earth titanates of La{sub 2}TiO{sub 5} and Nd{sub 2}TiO{sub 5}, where Ti cations are in five-fold coordination with oxygen, has been studied at high pressures by X-ray diffraction (XRD), Raman scattering measurements, and quantum mechanical calculations. Both XRD and Raman results indicated two pressure-induced phase transitions during the process. An orthorhombic super cell (a x b x 2c) formed at a pressure between 6 and 10 GPa, and then transformed to a hexagonal high-pressure phase accompanied by partial decomposition. The hexagonal high-pressure phase is quenchable. Detailed structural analysis indicated that the five-coordinated TiO{sub 5} polyhedramore » remain during the formation of super cell, but the orthorhombic-to-hexagonal phase transition at high pressures is a reconstructive process, and the five-fold Ti-O coordination increased to more than 6. This phase transition sequence was verified by quantum mechanical calculations.« less

  11. Hydroxyapatite-coated Ti-6Al-4V part 2: the effects of post-deposition heat treatment at low temperatures.

    PubMed

    Lynn, A K; DuQuesnay, D L

    2002-05-01

    The present investigation explores the effects of a 90-h post-deposition annealing treatment at 400 degrees C in air on the crystallographic and chemical properties of a plasma-sprayed hydroxyapatite (HA) coating, the thickness and composition of the interfacial oxide layer, and the fatigue behaviour of the underlying Ti-6Al-4V substrate. X-ray diffraction analysis revealed that significant recovery of the crystalline HA structure occurred as a result of the treatment, however, as compared with results obtained through treatment at higher temperatures, recovery obtained through use of the present treatment was incomplete. X-ray photoelectron spectroscopy analysis showed no changes in the constituents of the oxide layer, with the oxide species TiO2, Al2O3, V2O5, V2O3, and VO2 present on both the as-sprayed and the heat-treated substrates. A change in film thickness was observed, however, as evidenced by a change in colour from opaque bronze to dark purple. The fatigue resistance of the substrate was found to be significantly reduced by the heat treatment, with the lives of heat-treated coupons with coatings of all thicknesses closely resembling those of as-sprayed coupons with thick HA coatings and uncoated stress-relieved coupons presented in Part I of this study. Stress relief was identified as the most likely cause of these reductions.

  12. “Ni{sub 5}TiO{sub 7}” is Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}

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

    Nalbandyan, V.B.

    2017-05-15

    It is shown that the compound known as Ni{sub 5}TiO{sub 7} and considered as a promising catalyst and oxidation product of alloys does not exist and its XRD pattern actually corresponds to Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} - Graphical abstract: XRD pattern of “Ni{sub 5}TiO{sub 7}” (top) is identical to that for Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} (bottom) based on single-crystal structural data. - Highlights: • Popular catalyst known as Ni{sub 5}TiO{sub 7} is actually Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}. • B{sub 2}O{sub 3} came from the flux used for crystal growth. • Some authors reporting this phase did notmore » use any boron compounds.« less

  13. Large ferroelectric polarization of TiN/Hf0.5Zr0.5O2/TiN capacitors due to stress-induced crystallization at low thermal budget

    NASA Astrophysics Data System (ADS)

    Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Young-Chul; Lucero, Antonio T.; Young, Chadwin D.; Summerfelt, Scott R.; San, Tamer; Colombo, Luigi; Kim, Jiyoung

    2017-12-01

    We report on atomic layer deposited Hf0.5Zr0.5O2 (HZO)-based capacitors which exhibit excellent ferroelectric (FE) characteristics featuring a large switching polarization (45 μC/cm2) and a low FE saturation voltage (˜1.5 V) as extracted from pulse write/read measurements. The large FE polarization in HZO is achieved by the formation of a non-centrosymmetric orthorhombic phase, which is enabled by the TiN top electrode (TE) having a thickness of at least 90 nm. The TiN films are deposited at room temperature and annealed at 400 °C in an inert environment for at least 1 min in a rapid thermal annealing system. The room-temperature deposited TiN TE acts as a tensile stressor on the HZO film during the annealing process. The stress-inducing TiN TE is shown to inhibit the formation of the monoclinic phase during HZO crystallization, forming an orthorhombic phase that generates a large FE polarization, even at low process temperatures.

  14. 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.

  15. Nanosecond pulsed laser micromachining for experimental fatigue life study of Ti-3Al-2.5V tubes

    NASA Astrophysics Data System (ADS)

    Lin, Yaomin; Gupta, Mool C.; Taylor, Robert E.; Lei, Charles; Stone, William; Spidel, Tom; Yu, Michael; Williams, Reanne

    2009-01-01

    Defects on external surface of in-service hydraulic tubes can reduce total life cycles for operation. Evaluation of fatigue life of the tubes with damage is thus critical for safety reasons. A methodology of generating defects in the Ti-3Al-2.5V tube—a widely used pipeline in hydraulic systems of aircrafts—using nanosecond pulsed laser for experimental fatigue life study is described in this paper. Straight tubes of five different sizes were laser micromachined to generate notches of given length and depths on the outside surface. Approaches were developed to precisely control the notch dimensions. The laser-notched tubes were tested with cyclic internal impulse pressure and fatigue life was measured. The laser notches and fatigue cracks were characterized after the test. It is concluded that laser micromachining generated consistent notches, and the influence of notch depth on fatigue life of the tube is significant. Based on the experimental test results, the relationship between the fatigue life of the Ti-3Al-2.5V tube and the notch depth was revealed. The research demonstrated that laser micromachining is applicable for experimental fatigue life study of titanium tubes. The presented test data are useful for estimating the damage limits of the titanium tubes in service environment and for further theoretical studies.

  16. Preparation of TiO2/Ag/TiO2 (TAT) multilayer films with optical and electrical properties enhanced by using Cr-added Ag film

    NASA Astrophysics Data System (ADS)

    Loka, Chadrasekhar; Lee, Kee-Sun

    2017-09-01

    The dielectric-metal-dielectric tri-layer films have attracted much attention by virtue of their low-cost and high quality device performance as a transparent conductive electrode. Here, we report the deposition of Cr doped Ag films sandwiched between thin TiO2 layers and investigation on the surface microstructure, optical and electrical properties depending on the thickness of the Ag(Cr). The activation energy (1.18 eV) for grain growth of Ag was calculated from the Arrhenius plot using the law Dn -D0n = kt , which was comparable to the bulk diffusion of Ag. This result indicated the grain growth of Ag was effectively retarded by the Cr addition, which was presumed to related with blocking the surface and grain boundary diffusion due to Cr segregation. Based on thermal stability of Cr added Ag film, we deposited TiO2/Ag(Cr)/TiO2 (TAT) multilayer thin films and with a 10 nm thick Ag(Cr), the TAT films showed high optical transmittance in the visible region (94.2%), low electrical resistivity (8.66 × 10-5 Ω cm), and hence the high figure of merit 57.15 × 10-3 Ω-1 was achieved. The high transmittance of the TAT film was believed to be attributed to the low optical loss due to a reduction in the Ag layer thickness, the surface plasmon effect, and the electron scattering reduced by the Ag layer with a low electrical resistivity.

  17. Addition of DNA to CrVI and Cytochrome b5 Containing Proteoliposomes Leads to Generation of DNA Strand Breaks and CrIII Complexes

    PubMed Central

    Borthiry, Griselda R.; Antholine, William E.; Myers, Judith M.; Myers, Charles R.

    2009-01-01

    Chromium (Cr) is a cytotoxic metal that can be associated with a variety of types of DNA damage, including Cr-DNA adducts and strand breaks. Prior studies with purified human cytochrome b5 and NADPH :P450 reductase in reconstituted proteoliposomes (PLs) demonstrated rapid reduction of CrVI (hexavalent chromium, as CrO42− ), and the generation of CrV, superoxide (O2·−) , and hydroxyl radical (HO˙). Studies reported here examined the potential for the species produced by this system to interact with DNA. Strand breaks of purified plasmid DNA increased over time aerobically, but were not observed in the absence of O2. CrV is formed under both conditions, so the breaks are not mediated directly by CrV. The aerobic strand breaks were significantly prevented by catalase and EtOH, but not by the metal chelator diethylenetriaminepentaacetic acid (DTPA), suggesting that they are largely due to HO˙ from Cr-mediated redox cycling. EPR was used to assess the formation of Cr-DNA complexes. Following a 10-min incubation of PLs, CrO42− , and plasmid DNA, intense EPR signals at g = 5.7and g = 5.0 were observed. These signals are attributed to specific CrIII complexes with large zero field splitting (ZFS). Without DNA, the signals in the g = 5 region were weak. The large ZFS signals were not seen, when CrIIICl3 was incubated with DNA, suggesting that the CrIII–DNA interactions are different when generated by the PLs. After 24 h, a broad signal at g = 2 is attributed to CrIII complexes with a small ZFS. This g = 2 signal was observed without DNA, but it was different from that seen with plasmid. It is concluded that EPR can detect specific CrIII complexes that depend on the presence of plasmid DNA and the manner in which the CrIII is formed. PMID:18729091

  18. Observation of magnetization and exchange bias reversals in NdFe0.5Cr0.5O3

    NASA Astrophysics Data System (ADS)

    Sharannia, M. P.; De, Santanu; Singh, Ripandeep; Das, A.; Nirmala, R.; Santhosh, P. N.

    2017-05-01

    Polycrystalline NdFe0.5Cr0.5O3 has orthorhombic structure with Pnma space group and is magnetically ordered at room temperature as confirmed by neutron diffraction. The magnetic structure involves CxGyFz type ordering of Fe3+/Cr3+ ions. NdFe0.5Cr0.5O3 shows magnetization reversal and sign reversal of exchange bias at 16 K. Nd3+ moments that get induced by the internal field of |Fe+Cr| sublattice couple antiferromagnetically with the ferromagnetic component of |Fe+Cr| sublattice. Nd3+ moments overcome the |Fe+Cr| moments at 16 K below which the material shows negative magnetization and positive exchange bias.

  19. Magnetic and thermoelectric properties of the ternary pseudo-hollandite BaxCr5Se8 (0.5 < x < 0.55) solid solution.

    PubMed

    Lefèvre, Robin; Berthebaud, David; Bux, Sabah; Hébert, Sylvie; Gascoin, Franck

    2016-07-26

    The structure of Ba0.5Cr5Se8 has been recently resolved, and its thermoelectric and magnetic properties have been studied. A ZT of 0.12 was found at around 800 K. Here, we report a study on the pseudo-hollandite BaxCr5Se8 solid-solution with 0.5 ≤ x ≤ 0.55 and its thermoelectric and magnetic properties. There is no significant impact either on the cell parameters depending on the cation content or on the magnetic properties. However, thermoelectric properties are radically changed depending on x content. While the low thermal conductivity, around 0.8 W m(-1) K(-1), remains similar for all samples, a respective increase and decrease of the resistivity and the Seebeck coefficient are observed with increasing Ba content. The maximum Seebeck coefficient is found with Ba0.5Cr5Se8 at around 635 K with 315 μV K(-1), and the Seebeck coefficient then decreases and is correlated with an activation of minority charge carriers confirmed by Hall measurements. A similar but steeper behavior is observed for the Ba0.55Cr5Se8 temperature dependence plot at around 573 K. Finally, the best thermoelectric performances are found using the lowest content of Ba, unlike when x tends to 0.55, ZT approaches a tenth of the initial best value. BaxCr5Se8 compounds are antiferromagnetic with TN = 58 K. A large peak in thermal conductivity is observed around the antiferromagnetic transition for all stoichiometry.

  20. Gibbs free energy difference between the undercooled liquid and the beta phase of a Ti-Cr alloy

    NASA Technical Reports Server (NTRS)

    Ohsaka, K.; Trinh, E. H.; Holzer, J. C.; Johnson, W. L.

    1992-01-01

    The heat of fusion and the specific heats of the solid and liquid have been experimentally determined for a Ti60Cr40 alloy. The data are used to evaluate the Gibbs free energy difference, delta-G, between the liquid and the beta phase as a function of temperature to verify a reported spontaneous vitrification (SV) of the beta phase in Ti-Cr alloys. The results show that SV of an undistorted beta phase in the Ti60Cr40 alloy at 873 K is not feasible because delta-G is positive at the temperature. However, delta-G may become negative with additional excess free energy to the beta phase in the form of defects.

  1. Shock Compression of the New 47Zr45Ti5Al3V Alloys up to 200 GPa

    NASA Astrophysics Data System (ADS)

    Zhang, Pin-Liang; Gong, Zi-Zheng; Ji, Guang-Fu; Wang, Qing-Song; Song, Zhen-Fei; Cao, Yan; Wang, Xiang

    2013-06-01

    Shock compression experiments on a new kind of 47Zr45Ti5Al3V alloys at pressures between 28 and 200 GPa are performed using a two-stage light gas gun. The Hugoniot data are obtained by combining the impedance-match method and the electrical probe technique. The relationship between the shock wave velocity Us and particle velocity up can be described linearly by Us = 4.324(±0.035) + 1.177(±0.012)up. No obvious evidence of phase transition is found in the shock compression pressure range. The calculated Us - up relationship obtained from the additive principle is different from the experimental data, indicating that the α → β phase transition occurs below 28 GPa. The Grüneisen parameter γ obtained from the experimental data can be expressed by γ = 1.277(ρ0/ρ). The zero-pressure bulk modulus B0s = 97.96 GPa and its pressure derivative B'0s = 3.68. The P—V—T equation of state for 47Zr45Ti5Al3V is given using the Vinet equation of state to describe the cold curve and the Debye model for the thermal contributions.

  2. 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.

  3. Tensile deformation damage in SiC reinforced Ti-15V-3Cr-3Al-3Sn

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Saltsman, James F.

    1991-01-01

    The damage mechanisms of a laminated, continuous SiC fiber reinforced Ti-15V-3Cr-3Al-3Sn (Ti-15-3) composite were investigated. Specimens consisting of unidirectional as well as cross-ply laminates were pulled in tension to failure at room temperature and 427 C and subsequently examined metallographically. Selected specimens were interrupted at various strain increments and examined to document the development of damage. When possible, a micromechanical stress analysis was performed to aid in the explanation of the observed damage. The analyses provide average constituent microstresses and laminate stresses and strains. It was found that the damage states were dependent upon the fiber architecture.

  4. Dielectric, magnetic and structural properties of novel multiferroic Eu(0.5)Ba(0.5)TiO(3) ceramics.

    PubMed

    Goian, V; Kamba, S; Nuzhnyy, D; Vaněk, P; Kempa, M; Bovtun, V; Knížek, K; Prokleška, J; Borodavka, F; Ledinský, M; Gregora, I

    2011-01-19

    Dielectric properties of Eu(0.5)Ba(0.5)TiO(3) ceramics were investigated between 10 and 300 K in the frequency range of 1 MHz-100 THz. Permittivity exhibits a strong peak near the ferroelectric phase transition at 215 K. This is mainly due to softening of the lowest frequency polar phonon revealed in THz and infrared spectra. Dielectric relaxation was observed also below the ferroelectric soft mode frequency in the whole investigated temperature region, but it is probably caused by some defects such as Eu(3 + ) cations or oxygen vacancies. This implies that the ferroelectric phase transition has predominantly a displacive character. Raman scattering spectra revealed a lowering of crystal symmetry in the ferroelectric phase and XRD analysis indicated orthorhombic A2mm symmetry below 215 K. The magnetic measurements performed at various frequencies in the field cooled and field heating regime after cooling in zero magnetic fields excluded spin glass behavior and proved an antiferromagnetic order below 1.9 K in Eu(0.5)Ba(0.5)TiO(3).

  5. Catalytic oxidation of 1,2-DCBz over V2O5/TiO2-CNTs: effect of CNT diameter and surface functional groups.

    PubMed

    Du, Cuicui; Wang, Qiulin; Peng, Yaqi; Lu, Shengyong; Ji, Longjie; Ni, Mingjiang

    2017-02-01

    A series of V 2 O 5 /TiO 2 -carbon nanotube (CNT) catalysts were prepared and tested to decompose gaseous 1,2-dichlorobenzene (1,2-DCBz). Several physicochemical methods, including nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and H 2 temperature-programmed reduction (TPR) were employed to characterise their physicochemical properties. To better understand the effect of CNT properties on the reactivity of V 2 O 5 /TiO 2 -CNT catalysts, the 1,2-DCBz residue remaining in the off-gas and on the catalyst surface were both collected and analysed. The results indicate that the outer diameter and the surface functional groups (hydroxide radical and carboxyl) of CNTs significantly influence upon the catalytic activity of CNT-containing V 2 O 5 /TiO 2 catalysts: the CNT outer diameter mainly affects the aggregation of CNTs and the π-π interaction between the benzene ring and CNTs, while the introduction of -OH and -COOH groups by acid treatment can further enlarge specific surface area (SSA) and contribute to a higher average oxidation state of vanadium (V aos ) and supplemental surface chemisorbed oxygen (O ads ). In addition, the enhanced mobility of lattice oxygen (O latt) also improves the oxidation ability of the catalysts.

  6. Influence of Bond Coats on the Microstructure and Mechanical Behaviors of HVOF-Deposited TiAlNb Coatings

    NASA Astrophysics Data System (ADS)

    Zeng, H. J.; Zhang, L. Q.; Lin, J. P.; He, X. Y.; Zhang, Y. C.; Jia, P.

    2012-12-01

    Hot dip galvanizing has been extensively employed for corrosion protection of steel structures. However, during the process of galvanization, the corrosion in molten zinc brings many problems to galvanization industry. In this study, as a material of corrosion resistance to molten zinc intended for application in Hot-dip galvanization, HVOF Ti28.15Al63.4Nb8.25Y (at.%) coatings with different bond coats (NiCr5Al, NiCoCrAlY, CoCrAlYTaSi, and NiCr80/20) were deposited onto 316L stainless steel substrate, respectively. The influences of different bond coats on HVOF Ti28.15Al63.4Nb8.25Y coatings were investigated. The results showed that bond coat had an obvious influence on improving the mechanical properties of HVOF Ti28.15Al63.4Nb8.25Y coatings. HVOF Ti28.15Al63.4Nb8.25Y coatings with NiCoCrAlY bond coat displayed the best mechanical properties. However, bond coats had no obvious effects on the microstructure, porosity, and hardness of HVOF Ti28.15Al63.4Nb8.25Y top coatings. The effects of as-received powder morphology and grain size on the characteristics of coatings were also discussed.

  7. Low-cost Fe--Ni--Cr alloys for high temperature valve applications

    DOEpatents

    Muralidharan, Govindarajan

    2017-03-28

    An Fe--Ni--Cr alloy is composed essentially of, in terms of weight percent: 1 to 3.5 Al, up to 2 Co, 15 to 19.5 Cr, up to 2 Cu, 23 to 40 Fe, up to 0.3 Hf, up to 4 Mn, 0.15 to 2 Mo, up to 0.15 Si, up to 1.05 Ta, 2.8 to 4.3 Ti, up to 0.5 W, up to 0.06 Zr, 0.02 to 0.15 C, 0.0001 to 0.007 N, balance Ni, wherein, in terms of atomic percent: 6.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.10, 0.33.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.065, 4.ltoreq.(Fe+Cr)/(Al+Ti+Zr+Hf+Ta).ltoreq.10, the alloy being essentially free of Nb and V.

  8. Crystal structure and electrical conductivity of lanthanum-calcium chromites-titanates La 1-xCa xCr 1-yTi yO 3-δ ( x=0-1, y=0-1)

    NASA Astrophysics Data System (ADS)

    Vashook, V.; Vasylechko, L.; Zosel, J.; Gruner, W.; Ullmann, H.; Guth, U.

    2004-10-01

    Five series of perovskite-type compounds in the system La1-xCaxCr1-yTiyO3 with the nominal compositions y = 0 , x = 0 - 0.5 ; y = 0.2 , x = 0.2 - 0.8 ; y = 0.5 , x = 0.5 - 1.0 ; y = 0.8 , x = 0.6 - 1.0 and y = 1 , x = 0.8 - 1 were synthesized by a ceramic technique in air (final heating 1350 °C). On the basis of the X-ray analysis of the samples with (Ca/Ti)⩾1, the phase diagram of the CaTiO3-LaCrIIIO3-CaCrIVO3 quasi-ternary system was constructed. Extended solid solution with a wide homogeneity range is formed in the quasi-ternary system CaCrIVO3-CaTiO3-LaCrIIIO3. The solid solution La(1-x‧-y)Ca(x‧+y)CrIVx‧CrIII(1-x‧-y)TiyO3 exists by up to 0.6-0.7 mol fractions of CaCrIVO3 (x‧ < 0.6 - 0.7) at the experimental conditions. The crystal structure of the compounds is orthorhombic in the space group Pbnm at room temperature. The lattice parameters and the average interatomic distances of the samples within the solid solution ranges decrease uniformly with increasing Ca content. Outside the quasi-ternary system, the nominal compositions La0.1Ca0.9TiO3, La0.2Ca0.8TiO3, La0.4Ca0.6Cr0.2Ti0.8O3 and La0.3Ca0.7Cr0.2Ti0.8O3 in the system La1-xCaxCr1-yTiyO3 were found as single phases with an orthorhombic structure. In the temperature range between 850 and 1000 °C, the synthesized single-phase compositions are stable at pO2=6×10-16-0.21×105 Pa. Oxygen stoichiometry and electrical conductivity of the separate compounds were investigated as functions of temperature and oxygen partial pressure. The chemical stability of these oxides with respect to oxygen release during thermal dissociation decreases with increasing Ca-content. At 900 °C and oxygen partial pressure 1×10-15-0.21×105 Pa, the compounds with x > y (acceptor doped) are p-type semiconductors and those with x < y (donor doped) and x = y are n-type semiconductors. The type and level of electrical conductivity are functions of the concentration ratios of cations occupying the B-sites of the perovskite

  9. Inhibition of B16-BL6 melanoma lung colonies by semisynthetic sulfaminoheparosan sulfates from E. coli K5 polysaccharide.

    PubMed

    Poggi, Andreina; Rossi, Cosmo; Casella, Nicola; Bruno, Cristiana; Sturiale, Luisella; Dossi, Carla; Naggi, Annamaria

    2002-08-01

    Heparin (H), heparan sulfate (HS), and related glycosaminoglycans can inhibit cancer cell invasion, possibly due to their ability to interact with vascular growth factors, adhesion molecules, endoglycosidases, and signaling proteins, in addition to the well-known effects on the clotting system. We evaluated the antitumor activity of a series of semisynthetic sulfaminoheparosan sulfates (SAHSs) with different degree and distribution of sulfates, obtained by chemical modifications of the E. coli K5 polysaccharide, namely type A, B, and C compounds. B16-BL6 melanoma cells (10 5 cells/mouse) were injected intravenously (i.v.) in a lateral tail vein of C57BL6 mice at a dose of 0.5 mg/ mouse together with test compounds. Tumor lung nodules were significantly reduced as compared with controls only by H (95.5 +/- 1.0% inhibition), SAHS-2 (84.2 +/- 5.0% inhibition), and SAHS-4 (91.1 +/- 4.2% inhibition), among compounds tested. SAHS-2 and SAHS-4 are type B compounds, with a sulfate/carboxylate ratio similar to that of H. A typical mammalian HS showed only 54.8% inhibition. Supersulfated low-molecular-weight heparin and heparan sulfate (ssLMWH and ssLMWHS) showed an activity similar to that of unfractionated compounds. H and SAHS-4 inhibited dose dependently B16-BL6 lung colonies, with IC-50 values of 0.05 and 0.1 mg/mouse, respectively. The relationship with ex vivo anticoagulant potency was evaluated by activated partial thromboplastin time (aPTT) on mouse plasma at different time intervals after i.v. injection (0.1 to 0.5 mg/mouse) of the compound. H showed a dose-dependent anticoagulant activity lasting up to 2 hours, whereas SAHS-4 showed a potent anticoagulant effect only at a dose of 0.5 mg/mouse. Accordingly, H but not SAHS-4 consistently inhibited B16-BL6 lung colonies when given 1 hour before tumor cells. SAHS-4 derivatives, with different size and/or affinity depleted of AT binding sites, showed an inhibitory effect on B16-BL6 melanoma similar to that of SAHS-4

  10. Synthesis and electronic properties of Fe2TiO5 epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Osada, Motoki; Nishio, Kazunori; Hwang, Harold Y.; Hikita, Yasuyuki

    2018-05-01

    We investigate the growth phase diagram of pseudobrookite Fe2TiO5 epitaxial thin films on LaAlO3 (001) substrates using pulsed laser deposition. Control of the oxygen partial pressure and temperature during deposition enabled selective stabilization of (100)- and (230)-oriented films. In this regime, we find an optical gap of 2.1 eV and room temperature resistivity in the range of 20-80 Ω cm, which are significantly lower than α-Fe2O3, making Fe2TiO5 potentially an ideal inexpensive visible-light harvesting semiconductor. These results provide a basis to incorporate Fe2TiO5 in oxide heterostructures for photocatalytic and photoelectrochemical applications.

  11. 28 CFR 63.5 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PROCEDURES § 63.5 Responsibilities. (a) The Assistant Attorney General, Land and Natural Resources Division..., to comply with the Orders. Considerations for making this selection are whether a component: (i...

  12. 28 CFR 63.5 - Responsibilities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PROCEDURES § 63.5 Responsibilities. (a) The Assistant Attorney General, Land and Natural Resources Division..., to comply with the Orders. Considerations for making this selection are whether a component: (i...

  13. A quasi-in-situ EBSD observation of the transformation from rolling texture to recrystallization texture in V-4Cr-4Ti alloy

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

    Peng, Lixia

    Recrystallization texture evolution of rolled V-4Cr-4Ti alloy has been investigated by quasi-in-situ EBSD (electron back-scattering diffraction) method. Concurrently, the precipitates were characterized by SEM (Scanning Electron Microscopy). It was found that both the initial rolling textures and the distribution of the precipitates affected the formation of the recrystallization texture. It was revealed that the texture transformations of (558) 〈110〉 + (665) 〈110〉 to (334) 〈483〉 + (665) 〈1 1 2.4〉 were possibly attributed to the selective drag induced by the sparsely dispersed Ti-rich precipitates. While the densely distributed Ti-rich precipitates were responsible for the randomized recrystallization texture. Finally, when themore » precipitates were absent, the orientation changes from (112) 〈110〉 and (558) 〈110〉 to (111) 〈112〉 and (001) <110> to (001) <520> were observed. - Highlights: • Micro recrystallization texture evolution in V-4Cr-4Ti alloys is reported for the first time. • The volume fraction of Ti-rich precipitates has significant effect on the recrystallization texture evolution. • The dissolution of the Ti-rich precipitates above 1100 °C induces the strengthening of (111) <112> texture.« less

  14. Low cycle fatigue and creep fatigue interaction behavior of 9Cr-0.5Mo-1.8W-V-Nb heat-resistant steel at high temperature

    NASA Astrophysics Data System (ADS)

    Wang, Xiaowei; Zhang, Wei; Gong, Jianming; Wahab, Magd Abdel

    2018-07-01

    In this paper, Low Cycle Fatigue (LCF) and Creep-Fatigue Interaction (CFI) behavior of 9Cr-0.5Mo-1.8 W-V-Nb heat-resistant steel (ASME Grade P92 steel) at elevated temperature of 600 °C are investigated. Strain controlled LCF tests are conducted in fully reversed triangular waveform at different strain amplitudes ranging from 0.2% to 0.8%. CFI tests are conducted at 0.4% strain amplitude in trapezoid waveform with tensile hold time varying from 1 min to 60 min and compressive hold time varying from 1 min to 10 min. During LCF and CFI loadings, the evolution of cyclic stress, mean stress and stress relaxation behavior are investigated. It turns out that the softening behavior and lifetime degradation are dependent on strain amplitude, hold time and hold direction. In addition, the microstructure evolution and fracture behavior are characterized by optical, scanning and transmission electron microscope. The initial rapid softening behavior is attributed to the quick elimination of low angle boundaries, whereas no obvious microstructure alteration appears in the stable stage. Fracture behavior analysis reveals creep voids in long-term CFI tests facilitates the initiation and propagation of secondary cracks. The different responses of outer surface oxidation layer during cycling provides an explanation for severer damage of compressive hold and also accounts for the observed various fracture behavior of failed samples.

  15. Electrical analysis of inter-growth structured Bi4Ti3O12-Na0.5Bi4.5Ti4O15 ceramics

    NASA Astrophysics Data System (ADS)

    Jiang, Xiangping; Jiang, Yalin; Jiang, Xingan; Chen, Chao; Tu, Na; Chen, Yunjing

    2017-06-01

    Inter-growth bismuth layer-structured ferroelectrics (BLSFs), Bi4Ti3O12-Na0.5Bi4.5Ti4O15 (BIT-NBT), were successfully synthesized using the traditional solid-state reaction method. X-ray diffraction (XRD) Rietveld refinements were conducted using GSAS software. Good agreement and low residual are obtained. The XRD diffraction peaks can be well indexed into I2cm space group. The inter-growth structure was further observed in the high-resolution TEM image. Dielectric and impedance properties were measured and systematically analyzed. At the temperature range 763-923 K (below {T}{{c}}), doubly ionized oxygen vacancies (OVs) are localized and the short-range hopping leads to the relaxation processes with an activation energy of 0.79-1.01 eV. Above {T}{{c}}, the doubly charged OVs are delocalized and become free ones, which contribute to the long-range dc conduction. The reduction in relaxation species gives rise to a higher relaxation activation energy ˜1.6  eV. Project supported by the National Natural Science Foundation of China (Grant Nos. 51562014, 51262009, and 51602135).

  16. Effect of Element Substitution at V site on Thermoelectric Properties of Aurivillius Phase Bi2VO5.5

    NASA Astrophysics Data System (ADS)

    Kohri, Hitoshi; Yagasaki, Takayoshi

    2016-10-01

    Thermoelectric oxides are suitable at the high temperature range because of chemical stability. Aurivillius compounds are bismuth layered oxides, and known as oxygen ion conductors. The Aurivillius compounds consist of Perovskite layers and Bi-O layers. It is expected that nano-layered structure shows high Seebeck coefficients due to the quantum confinement of carriers in Perovskite layers. It was reported that the Seebeck coefficient of hot pressed specimens for Aurivillius phase Bi2VO5.5 was a high value of -28.3 mVK-1 at 1010 K, and the electrical resistivity of one was also a high value of 0.033 Ωm at 1010 K. In this paper, the effect of element substitution at the V site on thermoelectric properties of Aurivillius phase Bi2VO5.5 was investigated. Bi2V1- x M x O5.5 (M = Cr, Mo, W x = 0, 0.05, 0.1, 0.2) were prepared by solid-state reaction. The electrical resistivity of Cr-substituted specimens were indicated at larger values than the ones for unsubstituted specimens over the measurement temperature range. The resistivity above 800 K was reduced by substitution of W or Mo. W as a substituted element was effective for reducing the thermal conductivity of Bi2VO5.5. The maximum value of the dimensionless figure of merit ZT was 0.05 at 799 K for Bi2V0.8Mo0.2O5.5 and at 902 K for Bi2V0.8W0.1O5.5. The maximum ZT of an unsubstituted sample was 0.02 at 993 K. From these results, it was found that tungsten or molybdenum substitution was effective to improve ZT for Aurivillius phase Bi2VO5.5.

  17. Swift-heavy ion irradiation response and annealing behavior of A2TiO5 (A = Nd, Gd, and Yb)

    NASA Astrophysics Data System (ADS)

    Park, Sulgiye; Tracy, Cameron L.; Zhang, Fuxiang; Palomares, Raul I.; Park, Changyong; Trautmann, Christina; Lang, Maik; Mao, Wendy L.; Ewing, Rodney C.

    2018-02-01

    The structural responses of A2BO5 (A = Nd, Gd, and Yb; B = Ti) compositions irradiated by high-energy Au ions (2.2 GeV) were investigated using transmission electron microscopy, synchrotron X-ray diffraction and Raman spectroscopy. The extent of irradiation-induced amorphization depends on the size of the A-site cation, with smaller lanthanides having less susceptibility to the accumulation of radiation damage. In the track-overlapping regime, complete amorphization is observed in all three compounds, despite the ability of Yb2TiO5 to incorporate a great deal of structural disorder into its initial defect-fluorite structure (Fm-3m). This is attributed to the high cation radius ratio (A:B = 2:1), which reduces the stability of the structure upon ion irradiation. The fully-amorphized samples were subsequently isochronally heated at temperature intervals from 100 °C to 850 °C. X-ray diffraction analysis indicated a similar damage recovery process in Nd2TiO5 and Gd2TiO5, where both compositions recover their original structures (Pnma) at 850 °C. In contrast, Yb2TiO5 exhibited recrystallization of a metastable, non-equilibrium orthorhombic phase at 550 °C, prior to a transformation to the stable defect-fluorite phase (Fm-3m) at 625 °C. These compositional variations in radiation tolerance and thermal recovery processes are described in terms of the energetics of disordering during the damage and recrystallization processes.

  18. Low Temperature Phase Transformations in Copper-Quenched Ti-44.5Al-8Nb-2.5V Alloy

    PubMed Central

    Cao, Shouzhen; Xiao, Shulong; Chen, Yuyong; Xu, Lijuan; Wang, Xiaopeng; Han, Jianchao

    2017-01-01

    In this study, an easily controlled transformation similar to the β + α → β + α + γ and the analysis of metastable phases in a β solidifying Ti-44.5Al-8Nb-2.5V alloy were investigated. Therefore, a liquid alloy copper-quenching followed by annealing at an application temperature (850 °C) has been carried out. Following quenching, a microstructure composed of several supersaturated phases—the basket-weave β0 (βbv) phase, the plate-like α2 (αp) phase and the stripe-like γ (γs) phase—was obtained. In the annealing processes, phase transformations in the prior βbv and αp phases domain corresponded nicely to the β + α → β + α + γ transformation during solidification. Also, in the annealed γs phase, the kinetics of the phase transformations involving the metastable L12 phase was firstly detected by transmission electron microscopy (TEM). The L12 phase had a lattice structure similar to the γ phase, whereas the composition of the phase was similar to the α2 phase. The formation of the γ pre-twin phase with an anti-phase boundary (APB) was detected in the γs phase of the matrix. The orientation relationships between the γs and precipitated: γ (γp) phase are <101]γs//<114]γp, (101¯)γs//(1¯10)γp and (01¯0)γs//(221¯)γp. PMID:28772561

  19. Elevated Temperature Corrosion Studies of AlCrN and TiAlN Coatings by PAPVD on T91 Boiler Steel

    NASA Astrophysics Data System (ADS)

    Goyal, Lucky; Chawla, Vikas; Hundal, Jasbir Singh

    2017-11-01

    The present investigation discusses the hot corrosion behavior of AlCrN and TiAlN nano-coatings on T91 boiler steel by PAPVD process subjected to molten salt of Na2SO4-60%V2O5 at 900 °C for 50 cycles. Surface and cross-sectional studies were performed by AFM, SEM/EDS and XRD techniques to understand the corrosion kinetics and mechanism. T91 bare boiler steel as well as TiAlN-coated specimen has shown higher internal oxidation as well as weight gain. The better corrosion resistance of AlCrN-coated specimen has been observed by virtue of higher availability of Cr and Al in the oxide scale as well as adherent and dense coating. The betterment of AlCrN coating can be attributed to low internal oxidation as well as movement of Cr and Al toward oxide scale to form protective corrosion barriers.

  20. Friction and wear behaviour of plasma sprayed Cr2O3-TiO2 coating

    NASA Astrophysics Data System (ADS)

    Bagde, Pranay; Sapate, S. G.; Khatirkar, R. K.; Vashishtha, Nitesh; Tailor, Satish

    2018-02-01

    Cr2O3-25TiO2 coating was deposited by atmospheric plasma spray (APS) coating technique. Effect of load (5-30 N) and sliding velocity (0.25, 0.75 m s-1) on friction coefficient and abrasive wear behaviour of the Cr2O3-25TiO2 coating was studied. Mechanical and microstructural characterization of the Cr2O3-25TiO2 coating was carried out. With an increase in sliding velocity, abrasive wear rate and friction coefficient (COF) decreased while wear rate and friction coefficient showed an increasing trend with the load. The worn out surfaces were analyzed by SEM, EDS and XRD. At lower sliding velocity, XRD analysis revealed peaks of Ti2O3, Ti3O5, CrO2 and CrO3. In addition, peak of Ti4O7 was also detected at higher sliding velocity and at 30 N load. At higher sliding velocity medium to severe tribo oxidation was observed. XPS analysis of worn surfaces at both the sliding velocities, showed surface film of oxides of titanium and chromium along with Cr(OH)3. Magneli phase titanium oxides with sub stoichiometric composition, along with surface films of chromium oxides and hydroxides altered the friction and wear behaviour of the coating. The decrease in friction coefficient with an increase in sliding velocity was attributed to tribo oxides and tribochemical reaction films having lower shear strength with good lubricating properties. The mechanism of material removal involved plastic deformation at lower load whereas inter-granular and trans-granular fracture, delamination cracking and splat fracture was observed with an increase load from 10 N to 30 N.

  1. Fracture resistance of Ti-5Al-2.5Sn extra-low interstitial castings

    NASA Technical Reports Server (NTRS)

    Fiftal, C. F.; Bolstad, D. A.; Misra, M. S.

    1978-01-01

    Fracture toughness and cyclic crack propagation data for Ti-5Al-2.5Sn extra-low interstitial (ELI) castings, 0.51 and 2.54 cm (0.20 and 1.00 in.) thick, at 394, 294, 77, and 20 K (250, 70, -320, and -423 F), are presented. Both surface flaw and compact tension geometries were tested. Comparison is made with other titanium alloys in both wrought and cast forms. Crack propagation resistance is comparable to wrought Ti-5Al-2.5Sn ELI, even with the extremely coarse as-cast grain size encountered.

  2. Spin-phonon coupling and exchange interaction in Gd substituted YFe0.5Cr0.5O3

    NASA Astrophysics Data System (ADS)

    Singh, Karan; Sharma, Mohit K.; Mukherjee, K.

    2018-02-01

    We report the evolution of physical properties due to partial substitution of Gd on the Y site in a mixed metal oxide YFe0.5Cr0.5O3. This compound exhibits negative magnetization at low applied fields. Our investigations on Y1-xGdxFe0.5Cr0.5O3 (x = 0.0, 0.2, 0.4 and 0.6) compounds is carried out through magnetization and Raman spectroscopy studies. It is observed that even with 20% Gd substitution, the negative magnetization observed in YFe0.5Cr0.5O3 is suppressed. Due to magnetic rare earth ion Gd3+, additional exchange interaction of the form Gd-O-Fe/Cr dominates the magnetic interaction arising due to the transition metal ions. This results in positive magnetization in Gd-substituted compounds. Temperature dependent Raman spectroscopy along with magnetization studies revealed that the observed shifts of Raman mode is due to spin-phonon coupling. Hardening of Raman mode observed below 240 K in YFe0.5Cr0.5O3 weakens and softening of phonon modes was observed for Y0.4Gd0.6Fe0.5Cr0.5O3 compound. This implies that additional magnetic interactions due to Gd ions play a dominating role in dictating the behavior of the Gd-substituted compounds.

  3. Producing High-Quality Titanium Alloy by a Cost-Effective Route Combining Fast Heating and Hot Processing

    NASA Astrophysics Data System (ADS)

    Yang, Fei; Raynova, Stella; Singh, Ajit; Zhao, Qinyang; Romero, Carlos; Bolzoni, Leandro

    2018-02-01

    Powder metallurgy is a very attractive method for producing titanium alloys, which can be near-net-shape formed and have freedom in composition selection. However, applications are still limited due to product affordability. In this paper, we will discuss a possible cost-effective route, combining fast heating and hot processing, to produce titanium alloys with similar or even better mechanical properties than that of ingot metallurgy titanium alloys. Two titanium alloys, Ti-5Al-5V-5Mo-3Cr (Ti-5553) and Ti-5Fe, were successfully produced from HDH titanium powder and other master alloy powders using the proposed processing route. The effect of the processing route on microstructural variation and mechanical properties have been discussed.

  4. Investigation of features of plastic deformation and fracture of fine-crystalline V-4Ti-4Cr alloy

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

    Grinyaev, Konstantin V., E-mail: kvgrinyaev@inbox.ru; Tyumentsev, Alexander N., E-mail: tyuments@phys.tsu.ru; Siberian Physical-Technical Institute, Tomsk, 634050

    2014-11-14

    With the use of transmission electron microscopy the investigation of defect substructure was carried out in the V-4Ti-4Cr-(C, N, O) alloy with disperse strengthening (by nanoparticles of oxy-carbo-nitride phase) after deformation by active tension at temperatures of 20 and 800 °C. It has been shown that an important feature of plastic deformation is deformation localization with crystal lattice reorientation.

  5. Influence of applied electric field annealing on the microwave properties of (Ba0.5Sr0.5)TiO3 thin films

    NASA Astrophysics Data System (ADS)

    Cho, Kwang-Hwan; Lee, Chil-Hyoung; Kang, Chong-Yun; Yoon, Seok-Jin; Lee, Young-Pak

    2007-04-01

    The effect of heat treatment in electric field on the structure and dielectric properties at microwave range of rf magnetron sputtering derived (Ba0.5Sr0.5)TiO3 thin films have been studied. It has been demonstrated that postannealing in the proper electric field can increase the dielectric constant and the tunability. The increased out-of-plane lattice constant in the electric-annealed films indicated the formation of small polar regions with tetragonal structure, which are responsible for the increased dielectric constant and tunability. It was proposed that the segregation of Ti3+ ions caused by electric annealing could induce the formation of BaTiO3-like regions, which are ferroelectric at room temperature. And in dielectric loss, as the Ti-O bonding lengths increase, the energy scattering on the ferroelectric mode also increases. So, the value of dielectric loss is slightly increased.

  6. Mechanism of generation of large (Ti,Nb,V)(C,N)-type precipitates in H13 + Nb tool steel

    NASA Astrophysics Data System (ADS)

    Xie, You; Cheng, Guo-guang; Chen, Lie; Zhang, Yan-dong; Yan, Qing-zhong

    2016-11-01

    The characteristics and generation mechanism of (Ti,Nb,V)(C,N) precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of (Ti,Nb,V)(C,N) phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich (Ti,Nb,V)(C,N) precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2-5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of (Ti,Nb,V)(C,N) is concentrated. The average composition of the single Ti-V-rich phase is (Ti0.511V0.356Nb0.133)(C x N y ), whereas that for the single Nb-rich phase is (Ti0.061V0.263Nb0.676)(C x N y ). The calculation results based on the Scheil-Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later.

  7. Characterization of Au/PbTi0.5Fe0.5O3/Si structure for possible multiferroic based non-volatile memory applications

    NASA Astrophysics Data System (ADS)

    Nawaz, S.; Roy, S.; Tulapurkar, A. A.; Palkar, V. R.

    2017-03-01

    Magnetoelectric multiferroic PbTi0.5Fe0.5O3 films are deposited on a ⟨100⟩ conducting p-Si substrate without any buffer layer by using pulsed laser deposition and characterized for possible non-volatile memory applications. Their crystalline structure and surface morphology were characterized by using x-ray diffraction and AFM techniques. HRTEM was employed to determine the film-substrate interface. The electronic structure of the film was investigated by XPS, and no signature of metal was found for all the elements. The chemical shift of the Ti 2p XPS peak is attributed to the replacement of Ti with Fe in the PbTiO3 matrix. Piezoelectric force microscopy (PFM) results indicate the 180° phase shift of ferroelectric polarization. The upward self-polarization phenomenon is also observed in the PFM study. Magnetic and magneto-electric coupling measurements were carried out to confirm the magnetic nature and electro-magnetic coupling characteristics. C-V measurements exhibit clock-wise hysteresis loops with a maximum memory window of 1.2 V and a sweep voltage of ±7 V. This study could influence the fabrication of silicon compatible multiple memory device structures.

  8. 42 CFR 63.5 - How will NIH make awards?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false How will NIH make awards? 63.5 Section 63.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING TRAINEESHIPS § 63.5 How will NIH make awards? Subject to the regulations of this part, the Director may award...

  9. 42 CFR 63.5 - How will NIH make awards?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false How will NIH make awards? 63.5 Section 63.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING TRAINEESHIPS § 63.5 How will NIH make awards? Subject to the regulations of this part, the Director may award...

  10. 42 CFR 63.5 - How will NIH make awards?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false How will NIH make awards? 63.5 Section 63.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING TRAINEESHIPS § 63.5 How will NIH make awards? Subject to the regulations of this part, the Director may award...

  11. 42 CFR 63.5 - How will NIH make awards?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false How will NIH make awards? 63.5 Section 63.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING TRAINEESHIPS § 63.5 How will NIH make awards? Subject to the regulations of this part, the Director may award...

  12. 42 CFR 63.5 - How will NIH make awards?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false How will NIH make awards? 63.5 Section 63.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING TRAINEESHIPS § 63.5 How will NIH make awards? Subject to the regulations of this part, the Director may award...

  13. Synthesis and electronic properties of Fe 2TiO 5 epitaxial thin films

    DOE PAGES

    Osada, Motoki; Nishio, Kazunori; Hwang, Harold Y.; ...

    2018-05-02

    Here, we investigate the growth phase diagram of pseudobrookite Fe 2TiO 5 epitaxial thin films on LaAlO 3 (001) substrates using pulsed laser deposition. Control of the oxygen partial pressure and temperature during deposition enabled selective stabilization of (100)- and (230)-oriented films. In this regime, we find an optical gap of 2.1 eV and room temperature resistivity in the range of 20–80 Ω cm, which are significantly lower than α-Fe 2O 3, making Fe 2TiO 5 potentially an ideal inexpensive visible-light harvesting semiconductor. These results provide a basis to incorporate Fe 2TiO 5 in oxide heterostructures for photocatalytic and photoelectrochemicalmore » applications.« less

  14. Pressure-induced structural transformations in lanthanide titanates: La{sub 2}TiO{sub 5} and Nd{sub 2}TiO{sub 5}

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

    Zhang, F.X., E-mail: zhangfx@umich.ed; Wang, J.W.; Lang, M.

    The structure of orthorhombic rare earth titanates of La{sub 2}TiO{sub 5} and Nd{sub 2}TiO{sub 5}, where Ti cations are in five-fold coordination with oxygen, has been studied at high pressures by X-ray diffraction (XRD), Raman scattering measurements, and quantum mechanical calculations. Both XRD and Raman results indicated two pressure-induced phase transitions during the process. An orthorhombic super cell (axbx2c) formed at a pressure between 6 and 10 GPa, and then transformed to a hexagonal high-pressure phase accompanied by partial decomposition. The hexagonal high-pressure phase is quenchable. Detailed structural analysis indicated that the five-coordinated TiO{sub 5} polyhedra remain during the formationmore » of super cell, but the orthorhombic-to-hexagonal phase transition at high pressures is a reconstructive process, and the five-fold Ti-O coordination increased to more than 6. This phase transition sequence was verified by quantum mechanical calculations. - Graphical abstract: At high pressures, La{sub 2}TiO{sub 5} and Nd{sub 2}TiO{sub 5} transform from the orthorhombic phase to an axbx2c superlattice of the orthorhombic structure and then to a hexagonal high-pressure phase. Display Omitted« less

  15. 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.

  16. Lead-free Bi(Mg0.5Ti0.5)O3-modified 0.875Bi0.5Na0.5TiO3-0.125BaTiO3 ferroelectric ceramics with tetragonal structure and large field-induced strains

    NASA Astrophysics Data System (ADS)

    Li, Ling; Zhu, Mankang; Ren, Xiaowei; Wei, Qiumei; Zheng, Mupeng; Hou, Yudong

    2017-12-01

    A electrostrictive ceramics were designed by introducing Bi(Mg0.5Ti0.5)O3 into 0.875Bi0.5Na0.5TiO3-0.125BaTiO3 with tetragonal structure. All the specimens prepared by a conventional solid sintering technique exhibit the excellent sintering ability with a high relative density over 97%. It is found that, as BMT added, the specimens undergo a structure crossover from ferroelectric P4mm to ergodic P4bm, and the coexistence of both tetragonal structures takes bridge between them. A large field-induced strain of 0.30% and field-independent strain coefficient of 0.0254 m4/C2 occur at 4 mol.% BMT added. This material with excellent sinterability is suitable for the application in actuators and microposition controllers.

  17. Multifunctional Beta Ti Alloy with Improved Specific Strength

    NASA Astrophysics Data System (ADS)

    Park, Chan Hee; Hong, Jae-Keun; Lee, Sang Won; Yeom, Jong-Taek

    2017-12-01

    Gum metals feature properties such as ultrahigh strength, ultralow elastic modulus, superelasticity, and superplasticity. They are composed of elements from Groups 4 and 5 of the periodic table and exist when the valance electron concentration (\\overline{e/a}) is 4.24; the bond order (\\overline{Bo}) is 2.87; and the "d" electron-orbital energy level (\\overline{Md}) is 2.45 eV. Typical compositions include Ti-23Nb-2Zr-0.7Ta-O and Ti-12Ta-9Nb-6Zr-3 V-O, which contain large amounts of heavy Group-5 elements such as Nb and Ta. In the present study, to improve the specific strength of a multifunctional beta Ti alloy, three alloys (Ti-20Nb-5Zr-1Fe-O, Ti-12Zr-10Mo-4Nb-O, and Ti-24Zr-9Cr-3Mo-O) were designed by satisfying the above three requirements while adding Fe, Mo, and Cr, which are not only lightweight but also have strong hardening effects. Microstructural and mechanical property analyses revealed that Ti-20Nb-5Zr-1Fe-O has a 25% higher specific strength than gum metal while maintaining an ultralow elastic modulus.

  18. Swift-heavy ion irradiation response and annealing behavior of A 2TiO 5 (A = Nd, Gd, and Yb)

    DOE PAGES

    Park, Sulgiye; Tracy, Cameron L.; Zhang, Fuxiang; ...

    2017-09-28

    The structural responses of A 2BO 5 (A = Nd, Gd, and Yb; B = Ti) compositions irradiated by high-energy Au ions (2.2 GeV) were investigated using transmission electron microscopy, synchrotron X-ray diffraction and Raman spectroscopy. The extent of irradiation-induced amorphization depends on the size of the A-site cation, with smaller lanthanides having less susceptibility to the accumulation of radiation damage. In the track-overlapping regime, complete amorphization is observed in all three compounds, despite the ability of Yb 2TiO 5 to incorporate a great deal of structural disorder into its initial defect-fluorite structure (Fm-3m). This is attributed to the highmore » cation radius ratio (A:B = 2:1), which reduces the stability of the structure upon ion irradiation. The fully-amorphized samples were subsequently isochronally heated at temperature intervals from 100 °C to 850 °C. X-ray diffraction analysis indicated a similar damage recovery process in Nd 2TiO 5 and Gd 2TiO 5, where both compositions recover their original structures (Pnma) at 850 °C. In contrast, Yb2TiO5 exhibited recrystallization of a metastable, non-equilibrium orthorhombic phase at ~ 550 °C, prior to a transformation to the stable defect-fluorite phase (Fm-3m) at 625 °C. In conclusion, these compositional variations in radiation tolerance and thermal recovery processes are described in terms of the energetics of disordering during the damage and recrystallization processes.« less

  19. Swift-heavy ion irradiation response and annealing behavior of A 2TiO 5 (A = Nd, Gd, and Yb)

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

    Park, Sulgiye; Tracy, Cameron L.; Zhang, Fuxiang

    The structural responses of A 2BO 5 (A = Nd, Gd, and Yb; B = Ti) compositions irradiated by high-energy Au ions (2.2 GeV) were investigated using transmission electron microscopy, synchrotron X-ray diffraction and Raman spectroscopy. The extent of irradiation-induced amorphization depends on the size of the A-site cation, with smaller lanthanides having less susceptibility to the accumulation of radiation damage. In the track-overlapping regime, complete amorphization is observed in all three compounds, despite the ability of Yb 2TiO 5 to incorporate a great deal of structural disorder into its initial defect-fluorite structure (Fm-3m). This is attributed to the highmore » cation radius ratio (A:B = 2:1), which reduces the stability of the structure upon ion irradiation. The fully-amorphized samples were subsequently isochronally heated at temperature intervals from 100 °C to 850 °C. X-ray diffraction analysis indicated a similar damage recovery process in Nd 2TiO 5 and Gd 2TiO 5, where both compositions recover their original structures (Pnma) at 850 °C. In contrast, Yb2TiO5 exhibited recrystallization of a metastable, non-equilibrium orthorhombic phase at ~ 550 °C, prior to a transformation to the stable defect-fluorite phase (Fm-3m) at 625 °C. In conclusion, these compositional variations in radiation tolerance and thermal recovery processes are described in terms of the energetics of disordering during the damage and recrystallization processes.« less

  20. Understanding the effects of Cr doping in rutile TiO2 by DFT calculations and X-ray spectroscopy.

    PubMed

    Vásquez, G Cristian; Maestre, David; Cremades, Ana; Ramírez-Castellanos, Julio; Magnano, Elena; Nappini, Silvia; Karazhanov, Smagul Zh

    2018-06-07

    The effects of Cr on local environment and electronic structure of rutile TiO 2 are studied combining theoretical and experimental approaches. Neutral and negatively charged substitutional Cr impurities Cr Ti 0 and Cr Ti 1- as well as Cr-oxygen vacancy complex 2Cr Ti  + V O are studied by the density functional theory (DFT) within the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) functional. Experimental results based on X-Ray absorption spectroscopy (XAS) and X-Ray photoelectron spectroscopy (XPS) performed on Cr doped TiO 2 at the Synchrotron facility were compared to the theoretical results. It is shown that the electrons of the oxygen vacancy tend to be localized at the t 2g states of the Cr ions in order to reach the stable oxidation state of Cr 3+ . Effects of Cr on crystal field (CF) and structural distortions in the rutile TiO 2 cell were analyzed by the DFT calculations and XAS spectra revealing that the CF and tetragonal distortions in TiO 2 are very sensitive to the concentration of Cr.

  1. Crystal structures of lazulite-type oxidephosphates Ti IIITi IV3O 3(PO 4) 3 and MIII4Ti IV27O 24(PO 4) 24 ( MIII=Ti, Cr, Fe)

    NASA Astrophysics Data System (ADS)

    Schöneborn, M.; Glaum, R.; Reinauer, F.

    2008-06-01

    Single crystals of the oxidephosphates Ti IIITi IV3O 3(PO 4) 3 (black), Cr III4Ti IV27O 24(PO 4) 24 (red-brown, transparent), and Fe III4Ti IV27O 24(PO 4) 24 (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2 dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [Ti IIITi IV3O 3(PO 4) 3: Z=24, a=7.3261(9) Å, b=22.166(5) Å, c=39.239(8) Å, R1=0.029, w R2=0.084, 6055 independent reflections, 301 variables; Cr III4Ti IV27O 24(PO 4) 24: Z=1, a=7.419(3) Å, b=21.640(5) Å, c=13.057(4) Å, R1=0.037, w R2=0.097, 1524 independent reflections, 111 variables; Fe III4Ti IV27O 24(PO 4) 24: Z=1, a=7.4001(9) Å, b=21.7503(2) Å, c=12.775(3) Å, R1=0.049, w R2=0.140, 1240 independent reflections, 112 variables). For Ti IIITi IVO 3(PO 4) 3 a well-ordered structure built from dimers [Ti III,IV2O 9] and [Ti IV,IV2O 9] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr 4Ti 27O 24(PO 4) 24 and Fe 4Ti 27O 24(PO 4) 24, consisting of dimers [ MIIITi IVO 9] and [Ti IV,IV2O 9], monomeric [Ti IVO 6] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs Ti III4Ti IV27O 24(PO 4) 24 ( a=7.418(2) Å, b=21.933(6) Å, c=12.948(7) Å) is isotypic to the oxidephosphates MIII4Ti IV27O 24(PO 4) 24 ( MIII: Cr, Fe). The UV/vis spectrum of Cr 4Ti 27O 24(PO 4) 24 reveals a rather small ligand-field splitting Δ o=14,370 cm -1 and a very low nephelauxetic ratio β=0.72 for the chromophores [Cr IIIO 6] within the dimers [Cr IIITi IVO 9].

  2. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties

    PubMed Central

    Becker, Thorsten H.

    2018-01-01

    Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α’/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples. PMID:29342079

  3. Leaching of vanadium from waste V2O5-WO3/TiO2 catalyst catalyzed by functional microorganisms.

    PubMed

    Wang, Shuhua; Xie, Yaling; Yan, Weifu; Wu, Xuee; Wang, Chin-Tsan; Zhao, Feng

    2018-05-22

    Solid wastes are currently produced in large amounts. Although bioleaching of metals from solid wastes is an economical and sustainable technology, it has seldom been used to recycle metals from abandoned catalyst. In this study, the bioleaching of vanadium from V 2 O 5 -WO 3 /TiO 2 catalyst were comprehensively investigated through five methods: Oligotrophic way, Eutrophic way, S-mediated way, Fe-mediated way and Mixed way of S-mediated and Fe-mediated. The observed vanadium bioleaching effectiveness of the assayed methods was follows: S-mediated > Mixed > Oligotrophic > Eutrophic > Fe-mediated, which yielded the maximum bioleaching efficiencies of approximately 90%, 35%, 33%, 20% and 7%, respectively. The microbial community analysis suggested that the predominant genera Acidithiobacillus and Sulfobacillus from the S-mediated bioleaching way effectively catalyzed the vanadium leaching, which could have occurred through the indirect mechanism from the microbial oxidation of S 0 . In addition, the direct mechanism, involving direct electron transfer between the catalyst and the microorganisms that attached to the catalyst surface, should also help the vanadium to be leached more effectively. Therefore, this work provides guidance for future research and practical application on the treatment of waste V 2 O 5 -WO 3 /TiO 2 catalyst. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. β -decay Q values among the A = 50 Ti-V-Cr isobaric triplet and atomic masses of Ti 46 , 47 , 49 , 50 , V 50 , 51 , and Cr 50 , 52 – 54

    DOE PAGES

    Kandegedara, R. M. E. B.; Bollen, G.; Eibach, M.; ...

    2017-10-20

    This manuscript describes a measurement of the Q value for the highly forbidden beta-decays of 50V and the double electron capture decay of 50Cr. The Q value corresponds to the total energy released during the decay and is equivalent to the mass difference between parent and daughter atoms. This mass difference was measured using high precision Penning trap mass spectrometry with the Low Energy Beam and Ion Trap facility at the National Superconducting Cyclotron Laboratory. The Q value enters into theoretical calculations of the half-life and beta-decay spectrum for the decay, so improves these calculations. In addition the Q valuemore » corresponds to the end point energy of the beta-decay spectrum, which has been precisely measured for several highly-forbidden decays using modern low background detector techniques. Hence, our Q value measurements provide a test of systematics for these detectors. In addition, we have measured the absolute atomic masses of 46,47,49,50Ti, 50,51V, and 50,52-52Cr, providing improvements in precision by factors of up to 3. These atomic masses help to strengthen global evaluations of all atomic mass data, such as the Atomic Mass Evaluation.« less

  5. β -decay Q values among the A = 50 Ti-V-Cr isobaric triplet and atomic masses of Ti 46 , 47 , 49 , 50 , V 50 , 51 , and Cr 50 , 52 – 54

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

    Kandegedara, R. M. E. B.; Bollen, G.; Eibach, M.

    This manuscript describes a measurement of the Q value for the highly forbidden beta-decays of 50V and the double electron capture decay of 50Cr. The Q value corresponds to the total energy released during the decay and is equivalent to the mass difference between parent and daughter atoms. This mass difference was measured using high precision Penning trap mass spectrometry with the Low Energy Beam and Ion Trap facility at the National Superconducting Cyclotron Laboratory. The Q value enters into theoretical calculations of the half-life and beta-decay spectrum for the decay, so improves these calculations. In addition the Q valuemore » corresponds to the end point energy of the beta-decay spectrum, which has been precisely measured for several highly-forbidden decays using modern low background detector techniques. Hence, our Q value measurements provide a test of systematics for these detectors. In addition, we have measured the absolute atomic masses of 46,47,49,50Ti, 50,51V, and 50,52-52Cr, providing improvements in precision by factors of up to 3. These atomic masses help to strengthen global evaluations of all atomic mass data, such as the Atomic Mass Evaluation.« less

  6. Effect of TiC nano-particles on the mechanical properties of an Al-5Cu alloy after various heat treatments

    NASA Astrophysics Data System (ADS)

    Zhang, Qingquan; Zhang, Wei; Tian, Weisi; Zhao, Qinglong

    2017-12-01

    In this paper, the effects of TiC nano-particles on the mechanical properties of Al-5Cu alloy were investigated. Adding TiC nano-particles can effectively refine grain size and secondary dendritic arm. The ultimate tensile strength, yield strength and elongation of the Al-5Cu alloy in each of the three states (i.e. as-cast, solid-solution state and T6 state) were also improved by adding TiC nano-particles. Moreover, the elastic-plastic plane-strain fracture toughness (K J) and work of fracture ( wof) of Al-5Cu containing TiC were significantly higher than those of Al-5Cu without TiC after aging for 10 h. The addition of TiC nano-particles also led to finer and denser ‧ precipitates.

  7. Giant strain with ultra-low hysteresis and high temperature stability in grain oriented lead-free K0.5Bi0.5TiO3-BaTiO3-Na0.5Bi0.5TiO3 piezoelectric materials

    PubMed Central

    Maurya, Deepam; Zhou, Yuan; Wang, Yaojin; Yan, Yongke; Li, Jiefang; Viehland, Dwight; Priya, Shashank

    2015-01-01

    We synthesized grain-oriented lead-free piezoelectric materials in (K0.5Bi0.5TiO3-BaTiO3-xNa0.5Bi0.5TiO3 (KBT-BT-NBT) system with high degree of texturing along the [001]c (c-cubic) crystallographic orientation. We demonstrate giant field induced strain (~0.48%) with an ultra-low hysteresis along with enhanced piezoelectric response (d33 ~ 190pC/N) and high temperature stability (~160°C). Transmission electron microscopy (TEM) and piezoresponse force microscopy (PFM) results demonstrate smaller size highly ordered domain structure in grain-oriented specimen relative to the conventional polycrystalline ceramics. The grain oriented specimens exhibited a high degree of non-180° domain switching, in comparison to the randomly axed ones. These results indicate the effective solution to the lead-free piezoelectric materials. PMID:25716551

  8. Study on the decomposition of trace benzene over V2O5-WO3 ...

    EPA Pesticide Factsheets

    Commercial and laboratory-prepared V2O5–WO3/TiO2-based catalysts with different compositions were tested for catalytic decomposition of chlorobenzene (ClBz) in simulated flue gas. Resonance enhanced multiphoton ionization-time of flight mass spectrometry (REMPI-TOFMS) was employed to measure real-time, trace concentrations of ClBz contained in the flue gas before and after the catalyst. The effects of various parameters, including vanadium content of the catalyst, the catalyst support, as well as the reaction temperature on decomposition of ClBz were investigated. The results showed that the ClBz decomposition efficiency was significantly enhanced when nano-TiO2 instead of conventional TiO2 was used as the catalyst support. No promotion effects were found in the ClBz decomposition process when the catalysts were wet-impregnated with CuO and CeO2. Tests with different concentrations (1,000, 500, and 100 ppb) of ClBz showed that ClBz-decomposition efficiency decreased with increasing concentration, unless active sites were plentiful. A comparison between ClBz and benzene decomposition on the V2O5–WO3/TiO2-based catalyst and the relative kinetics analysis showed that two different active sites were likely involved in the decomposition mechanism and the V=O and V-O-Ti groups may only work for the degradation of the phenyl group and the benzene ring rather than the C-Cl bond. V2O5-WO3/TiO2 based catalysts, that have been used for destruction of a wide variet

  9. Enhanced ferroelectric properties and thermal stability of nonstoichiometric 0.92(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3 single crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Haiwu; Chen, Chao; Zhao, Xiangyong; Deng, Hao; Li, Long; Lin, Di; Li, Xiaobing; Ren, Bo; Luo, Haosu; Yan, Jun

    2013-11-01

    Bi deficient, Mn doped 0.92(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3 single crystals were grown by carefully controlled top-seeded solution growth method. Local structures were investigated by transmission electron microscopy. The site occupation and valence state of manganese were characterized by electron paramagnetic resonance spectrum. The leakage current density in the as-grown single crystals is effectively depressed. The introduced defect complexes suppress the temperature induced phase transformation, increasing the depolarization temperature (165 °C) and thermal stability of ferroelectric properties.

  10. Flexible tensile strain sensor based on lead-free 0.5Ba (Ti0.8Zr0.2) O3-0.5(Ba0.7Ca0.3) TiO3 piezoelectric nanofibers

    NASA Astrophysics Data System (ADS)

    Xing, Lindong; Zhu, Ruijian; Wang, Zengmei; Wang, Fengxia; Kimura, Hideo

    2017-09-01

    Here, we report our study results of a flexible piezoelectric tensile strain sensor which is fabricated by synthesizing 0.5Ba (Zr0.2Ti0.8) O3-0.5(Ba0.7Ca0.3) TiO3 (0.5BZT-0.5BCT) nanofibers via an electrospinning process. Our nanofibers show an ultrahigh d33 of 275 pm V-1. 0.5BZT-0.5BCT nanofibers and MW-CNTs are dispersed in polydimethylsiloxane (PDMS) to fabricate a highly stretchable and flexible tensile sensor, and the multiple roles of the MW-CNTs are probed and demonstrated. This nanofiber-based piezoelectric tensile strain sensor shows great resolution and sensitivity under external mechanical deformation. It is suitable for applications in complex environments.

  11. 44 CFR 63.5 - Coverage for contents removal.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 44 Emergency Management and Assistance 1 2014-10-01 2014-10-01 false Coverage for contents removal. 63.5 Section 63.5 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program IMPLEMENTATION OF SECTION 1306(c) OF THE NATIONAL FLOOD...

  12. Stabilization of the Ti{sub 3}Co{sub 5}B{sub 2}-type structure for Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} through Si–Ti substitution

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

    Xie, Weiwei, E-mail: weiweix@princeton.edu; Fuccillo, M.K.; Phelan, B.F.

    2015-07-15

    We report a route for designing and synthesizing Ti{sub 3}Co{sub 5}B{sub 2}-type compounds in the Ti–Ru–B system by using chemical substitution of Si for Ti to decrease the d-electron-based antibonding interactions that it is argued would otherwise drive an instability in this structure for unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2}. Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} with x=0.75, 1.00 and 1.25 nominal compositions crystalizes in the Ti{sub 3}Co{sub 5}B{sub 2} structure type using arc melting methods, whereas at lower doping levels (x=0.0, 0.25 and 0.50) the more complex Zn{sub 11}Rh{sub 18}B{sub 8}-type structure is stable. Electronic structure calculations show that in hypothetical,more » unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2} with the Ti{sub 3}Co{sub 5}B{sub 2}-type structure, the antibonding interactions are strong around the Fermi level between the Ti and Ru in the structure that form tetragonal prisms. We propose that weakening these strong interactions through the partial substitution of isovalent Si for Ti leads to the observed stability of the Ti{sub 3}Co{sub 5}B{sub 2}-type structure for Ti{sub 3−x}Si{sub x}Ru{sub 5}B{sub 2} for x≈1. - Graphical abstract: We present the designing and synthesizing of Ti{sub 3}Co{sub 5}B{sub 2}-type compounds in the Ti–Ru–B system by using chemical substitution of Si for Ti to decrease the d-electron-based antibonding interactions that would otherwise drive an instability in this structure for unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2}. Electronic structure calculations show that in hypothetical, unsubstituted Ti{sub 3}Ru{sub 5}B{sub 2} with the Ti{sub 3}Co{sub 5}B{sub 2}-type structure, the antibonding interactions are strong around the Fermi level between the Ti and Ru in the structure that form tetragonal prisms. We propose that weakening these strong interactions through the partial substitution of isovalent Si for Ti leads to the observed stability of the Ti{sub 3}Co{sub 5}B{sub 2}-type structure for

  13. Effect of Thermal Processes on the Electrical and Optical Properties of Fe2TiO5 Ceramics

    NASA Astrophysics Data System (ADS)

    Fajarin, R.; Widyastuti; Baqiya, M. A.; Putri, I. Y. S.

    2017-05-01

    Pseudobrookite (Fe2TiO5) is one of the Fe-Ti oxides that have been commonly studied. It is the most stable phase among the Fe-titanates. The multiferroic properties of Fe2TiO5 make the material can be used as a potential candidate for new applications due to the combination of semiconducting, magnetic, dielectric, and optical properties. In this research, Fe2TiO5 ceramics were synthesized using mechanical milling method for 7 h with various temperatures of 1100 °C, 1200 °C, and 1300 °C. Scanning electron microscopy (SEM) observation and x-ray diffraction (XRD) measurements were performed to analyze the microstructures and crystal structures of the Fe2TiO5 ceramics. In order to investigate the band gap of the Fe2TiO5, the UV-Vis Diffuse Reflectance measurements were conducted. It has been found that the Fe2TiO5 ceramic can be applied as a promising candidate for semiconducting devices in which the electrical conductivity and the band gap of the Fe2TiO5 ceramic were 1.73 × 10-7 Ω-1.cm-1 and 1.71 eV, respectively.

  14. An Analysis of Periodic Components in BL Lac Object S5 0716 +714 with MUSIC Method

    NASA Astrophysics Data System (ADS)

    Tang, J.

    2012-01-01

    Multiple signal classification (MUSIC) algorithms are introduced to the estimation of the period of variation of BL Lac objects.The principle of MUSIC spectral analysis method and theoretical analysis of the resolution of frequency spectrum using analog signals are included. From a lot of literatures, we have collected a lot of effective observation data of BL Lac object S5 0716 + 714 in V, R, I bands from 1994 to 2008. The light variation periods of S5 0716 +714 are obtained by means of the MUSIC spectral analysis method and periodogram spectral analysis method. There exist two major periods: (3.33±0.08) years and (1.24±0.01) years for all bands. The estimation of the period of variation of the algorithm based on the MUSIC spectral analysis method is compared with that of the algorithm based on the periodogram spectral analysis method. It is a super-resolution algorithm with small data length, and could be used to detect the period of variation of weak signals.

  15. Charge ordering in the metal-insulator transition of V-doped CrO2 in the rutile structure.

    PubMed

    Biswas, Sarajit

    2018-04-17

    Electronic, magnetic, and structural properties of pure and V-doped CrO 2 were extensively investigated utilizing density functional theory. Usually, pure CrO 2 is a half-metallic ferromagnet with conductive spin majority species and insulating spin minority species. This system remains in its half-metallic ferromagnetic phase even at 50% V-substitution for Cr within the crystal. The V-substituted compound Cr 0.5 V 0.5 O 2 encounters metal-insulator transition upon the application of on-site Coulomb repulsion U = 7 eV preserving its ferromagnetism in the insulating phase. It is revealed in this study that Cr 3+ -V 5+ charge ordering accompanied by the transfer of the single V-3d electron to the Cr-3dt 2g orbitals triggers metal-insulator transition in Cr 0.5 V 0.5 O 2 . The ferromagnetism of Cr 0.5 V 0.5 O 2 in the insulating phase arises predominantly due to strong Hund's coupling between the occupied electrons in the Cr-t 2g states. Besides this, the ferromagnetic Curie temperature (T c ) decreases significantly due to V-substitution. Interestingly, a structural distortion is observed due to tilting of CrO 6 or VO 6 octahedra across the metal-insulator transition of Cr 0.5 V 0.5 O 2 . Graphical abstract The V-doped compound Cr 0.5 V 0.5 O 2 is found a half-metallic ferromagnet (HMF) in the absence of on-site Coulomb interaction (U). This HMF behavor maintains up to U = 6 eV. Eventually, this system encounters metal-insulator transition (MIT) upon the application of U = 7 eV with a band gap of E g ~ 0.31 eV. Nevertheless, applications of higher U widen the band gaps. In this figure, calculated total (black), Cr-3d (red), V-3d (violet), and O-2p (blue) DOS of Cr 0.5 V 0.5 O 2 for U = 8 eV are illustrated. The system is insulating with a band gap of E g ~ 0.7 eV.

  16. Effects of heat treatment on microstructure and mechanical behaviour of additive manufactured porous Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Ahmadi, S. M.; Jain, R. K. Ashok Kumar; Zadpoor, A. A.; Ayas, C.; Popovich, V. A.

    2017-12-01

    Titanium and its alloys such as Ti6Al4V play a major role in the medical industry as bone implants. Nowadays, by the aid of additive manufacturing (AM), it is possible to manufacture porous complex structures which mimic human bone. However, AM parts are near net shape and post processing may be needed to improve their mechanical properties. For instance, AM Ti6Al4V samples may be brittle and incapable of withstanding dynamic mechanical loads due to their martensitic microstructure. The aim of this study was to apply two different heat treatment regimes (below and above β-transus) to investigate their effects on the microstructure and mechanical properties of porous Ti6Al4V specimens. After heat treatment, fine acicular α‧ martensitic microstructure was transformed to a mixture of α and β phases. The ductility of the heat-treated specimens, as well as some mechanical properties such as hardness, plateau stress, and first maximum stress changed while the density and elastic gradient of the porous structure remained unchanged.

  17. Fabrication of spinel Li4-xTi5O12 via ion exchange for high-rate lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Cheng, Chongling; Liu, Hongjiang; Li, Jun; Xue, Xin; Cao, Hui; Wang, Dayang; Shi, Liyi

    2015-06-01

    The present work demonstrates that lithium ions can be stepwise substituted by protons from spinel Li4Ti5O12 crystalline particles though simple ion-exchange in aqueous HCl solution with the aid of heat treatment. This enables us to continuously tune the Li-to-Ti stoichiometric ratios from 0.80 to 0.59, 0.41, 0.21, 0.15, and 0.09, thus transforming Li4Ti5O12 to Li4-xTi5O12 nanocrystals. The resulting nanocrystals maintain the spinel crystal structure when x becomes smaller than 3. Among as-prepared the Li4-xTi5O12 crystalline particles, Li1Ti5O12 shows the highest capacity of 193 mAh g-1 at 1C and 148 mAh g-1 at 20C, lower current impedance (47 Ω), significantly improved rate capability and fairly long cycle life. This excellent electrochemical performance makes spinel Li4-xTi5O12 particles as a promising anode candidate for lithium ion batteries superior.

  18. Heavy ion irradiations on synthetic hollandite-type materials: Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16} (A=Cr, Fe, Al)

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

    Tang, Ming, E-mail: mtang@lanl.gov; Tumurugoti, Priyatham; Clark, Braeden

    2016-07-15

    The hollandite supergroup of minerals has received considerable attention as a nuclear waste form for immobilization of Cs. The radiation stability of synthetic hollandite-type compounds described generally as Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16} (A=Cr, Fe, Al) were evaluated by heavy ion (Kr) irradiations on polycrystalline single phase materials and multiphase materials incorporating the hollandite phases. Ion irradiation damage effects on these samples were examined using grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). Single phase compounds possess tetragonal structure with space group I4/m. GIXRD and TEM observations revealed that 600 keV Kr irradiation-induced amorphization on single phasemore » hollandites compounds occurred at a fluence between 2.5×10{sup 14} Kr/cm{sup 2} and 5×10{sup 14} Kr/cm{sup 2}. The critical amorphization fluence of single phase hollandite compounds obtained by in situ 1 MeV Kr ion irradiation was around 3.25×10{sup 14} Kr/cm{sup 2}. The hollandite phase exhibited similar amorphization susceptibility under Kr ion irradiation when incorporated into a multiphase system. - Graphical abstract: 600 keV Kr irradiation-induced amorphization on single phase hollandites compounds occurred at a fluence between 2.5×10{sup 14} Kr/cm{sup 2} and 5×10{sup 14} Kr/cm{sup 2}. The hollandite phase exhibited similar amorphization susceptibility under Kr ion irradiation when incorporated into a multiphase system. This is also the first time that the critical amorphization fluence of single phase hollandite compounds were determined at a fluence of around 3.25×10{sup 14} Kr/cm{sup 2} by in situ 1 MeV Kr ion irradiation. Display Omitted.« less

  19. Enhancement in electrical and magnetic properties with Ti-doping in Bi0.5La0.5Fe0.5Mn0.5O3

    NASA Astrophysics Data System (ADS)

    Singh, Rahul; Gupta, Prince Kumar; Kumar, Shiv; Joshi, Amish G.; Ghosh, A. K.; Patil, S.; Chatterjee, Sandip

    2017-04-01

    In this investigation, we have synthesized Bi0.5La0.5Fe0.5Mn0.5-xTixO3 (where x = 0 and 0.05) samples. The Rietveld refinement of X-ray diffraction (XRD) patterns shows that the systems crystallize in the orthorhombic phase with the Pnma space group. The observed Raman modes support the XRD results. The appearance of prominent A1-3 and weak E-2 modes in Bi0.5La0.5Fe0.5Mn0.45Ti0.05O3 indicates the presence of chemically more active Bi-O covalent bonds. Ferromagnetism of Bi0.5La0.5Fe0.5Mn0.5O3 is enhanced by Ti doping at the Mn-site, indicating that these particular samples might be interesting for device applications.

  20. Characterization and application of the hetero-junction ZnFe2O4/TiO2 for Cr(VI) reduction under visible light

    NASA Astrophysics Data System (ADS)

    Rekhila, G.; Trari, M.; Bessekhouad, Y.

    2017-06-01

    The spinel ZnFe2O4 prepared by nitrate route is used as dispersed photons collector capable to sensitize TiO2 under visible light and to reduce Cr(VI) into trivalent state. The transport properties, optical and photo-electrochemical characterizations are correlated, to build the energetic diagram of the hetero-system ZnFe2O4/TiO2/CrO4 - solution. A gap of 1.97 eV is obtained for the spinel from the diffuse reflectance. The conduction band of ZnFe2O4 (-1.47 V SCE) favors the electrons injection into TiO2, permitting a physical separation of the charge carriers. The oxidation of oxalic acid by photoholes prevents the corrosion of the spinel. The best configuration ZnFe2O4 (75 %)/TiO2 (25 %) is used to catalyze the downhill reaction (2HCrO4 - + 3C2H4O4 + 1.5O2 + 8H+ → 2Cr3+ + 6CO2 + 11 H2O, Δ G° = -557 kcal mol-1). 60 % of Cr(VI) are reduced after 3 h of visible light illumination and the photoactivity follows a first-order kinetic with a half-life of 70 min. The water reduction competes with the HCrO4 - reduction which is the reason in the regression of the photoactivity; a hydrogen evolution rate of 24 µmol mg-1 h-1 is obtained.

  1. Incubation of cocaine cue reactivity associates with neuroadaptations in the cortical serotonin (5-HT) 5-HT2C receptor (5-HT2CR) system.

    PubMed

    Swinford-Jackson, S E; Anastasio, N C; Fox, R G; Stutz, S J; Cunningham, K A

    2016-06-02

    Intensification of craving elicited by drug-associated cues during abstinence occurs over time in human cocaine users while elevation of cue reactivity ("incubation") is observed in rats exposed to extended forced abstinence from cocaine self-administration. Incubation in rodents has been linked to time-dependent neuronal plasticity in the medial prefrontal cortex (mPFC). We tested the hypothesis that incubation of cue reactivity during abstinence from cocaine self-administration is accompanied by lower potency and/or efficacy of the selective serotonin (5-HT) 5-HT2C​ receptor (5-HT2CR) agonist WAY163909 to suppress cue reactivity and a shift in the subcellular localization profile of the mPFC 5-HT2CR protein. We observed incubation of cue reactivity (measured as lever presses reinforced by the discrete cue complex) between Day 1 and Day 30 of forced abstinence from cocaine relative to sucrose self-administration. Pharmacological and biochemical analyses revealed that the potency of the selective 5-HT2CR agonist WAY163909 to suppress cue reactivity, the expression of synaptosomal 5-HT2CR protein in the mPFC, and the membrane to cytoplasmic expression of the 5-HT2CR in mPFC were lower on Day 30 vs. Day 1 of forced abstinence from cocaine self-administration. Incubation of cue reactivity assessed during forced abstinence from sucrose self-administration did not associate with 5-HT2CR protein expression in the mPFC. Collectively, these outcomes are the first indication that neuroadaptations in the 5-HT2CR system may contribute to incubation of cocaine cue reactivity. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. 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

  3. Application of V2O5/WO3/TiO2 for Resistive-Type SO2 Sensors

    PubMed Central

    Izu, Noriya; Hagen, Gunter; Schönauer, Daniela; Röder-Roith, Ulla; Moos, Ralf

    2011-01-01

    A study on the application of V2O5/WO3/TiO2 (VWT) as the sensitive material for resistive-type SO2 sensor was conducted, based on the fact that VWT is a well-known catalyst material for good selective catalytic nitrogen oxide reduction with a proven excellent durability in exhaust gases. The sensors fabricated in this study are planar ones with interdigitated electrodes of Au or Pt. The vanadium content of the utilized VWT is 1.5 or 3.0 wt%. The resistance of VWT decreases with an increasing SO2 concentration in the range from 20 ppm to 5,000 ppm. The best sensor response to SO2 occurs at 400 °C using Au electrodes. The sensor response value is independent on the amount of added vanadium but dependent on the electrode materials at 400 °C. These results are discussed and a sensing mechanism is discussed. PMID:22163780

  4. Cr{sub 2}O{sub 5} as new cathode for rechargeable sodium ion batteries

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

    Feng, Xu-Yong; Chien, Po-Hsiu; Rose, Alyssa M.

    2016-10-15

    Chromium oxide, Cr{sub 2}O{sub 5}, was synthesized by pyrolyzing CrO{sub 3} at 350 °C and employed as a new cathode in rechargeable sodium ion batteries. Cr{sub 2}O{sub 5}/Na rechargeable batteries delivered high specific capacities up to 310 mAh/g at a current density of C/16 (or 20 mA/g). High-resolution solid-state {sup 23}Na NMR both qualitatively and quantitatively revealed the reversible intercalation of Na ions into the bulk electrode and participation of Na ions in the formation of the solid-electrolyte interphase largely at low potentials. Amorphization of the electrode structure occurred during the first discharge revealed by both NMR and X-ray diffractionmore » data. CrO{sub 3}-catalyzed electrolyte degradation and loss in electronic conductivity led to gradual capacity fading. The specific capacity stabilized at >120 mAh/g after 50 charge-discharge cycles. Further improvement in electrochemical performance is possible via electrode surface modification, polymer binder incorporation, or designs of new morphologies. - Graphical abstract: Electrochemical profile of a Cr{sub 2}O{sub 5}/Na battery cell and high-resolution solid-state {sup 23}Na MAS NMR spectrum of a Cr{sub 2}O{sub 5} electrode discharged to 2 V. - Highlights: • Cr{sub 2}O{sub 5} was synthesized and used as a new cathode in rechargeable Na ion batteries. • A high capacity of 310 mAh/g and an energy density of 564 Wh/kg were achieved. • High-resolution solid-state {sup 23}Na NMR was employed to follow the reaction mechanisms.« less

  5. Electronic properties of Cr-N codoped rutile TiO2(110) thin films

    NASA Astrophysics Data System (ADS)

    Cheng, Zhengwang; Zhang, Lili; Dong, Shihui; Ma, Xiaochuan; Ju, Huanxin; Zhu, Junfa; Cui, Xuefeng; Zhao, Jin; Wang, Bing

    2017-12-01

    We report our investigation on the electronic properties of Cr-N codoped rutile TiO2(110) single crystal thin films, homoepitaxially grown by pulsed-laser-deposition method, and characterized using scanning tunneling microscopy and spectroscopy (STM/STS), X-ray/ultraviolet photoemission spectroscopy (XPS/UPS), in combination with first-principles calculations. Our results show that the bandgap reduction of the TiO2(110) surface is mainly contributed by the delocalized states whose position is at 2.0 eV below the Fermi level, introduced by the substitutional codoped Cr-2N pair, which is evidenced by the accordance of the results between the STS spectra and the calculated DOS. The codoped Cr-N pair contributes the gap state at about 0.8 eV below the Fermi level, in consistent with the theoretical calculations. While, the monodoped Cr contributes the states either close to the valence band maximum or the conduction band minimum, which should not contribute to the bandgap reduction too much. Our experimental results joint with theoretical calculations provide an atomic view of the bandgap reduction of the rutile TiO2(110) surface, which indicates that the excess substitutional N atoms should be important to efficiently narrow the bandgap by introducing the Cr-2N pairs.

  6. Microstructures and mechanical properties of powder injection molded Ti-6Al-4V/HA powder.

    PubMed

    Thian, E S; Loh, N H; Khor, K A; Tor, S B

    2002-07-01

    Taguchi method with an L9 orthogonal array was employed to investigate the sintered properties of Ti-6Al-4V/HA tensile bars produced by powder injection molding. The effects of sintering factors at the 90% significance level: sintering temperature (1050 degrees C, 1100 degrees C and 1150 degrees C), heating rate (5 degrees C/min, 7.5 degrees C/min and 10 degrees C/min), holding time (30, 45 and 60 min) and cooling rate (5 degrees C/min, 20 degrees C/min and 40 degrees C/min) were investigated. Results showed that sintering temperature, heating rate and cooling rate have significant effects on sintered properties, whereas the influence of holding time was insignificant. It was found that a sintering temperature of 1100 degrees C, a heating rate of 7.5 degrees C/min and a cooling rate of 5 degrees C/min increased the relative density, Vicker's microhardness, flexural strength and flexural modulus. However, a further increment of sintering temperature to 1150 degrees C did not show any discernable improvement in the relative density and Vicker's microhardness, but there was a slight increase of 0.6% and 0.9% in the flexural strength and flexural modulus, respectively. Mechanically strong Ti-6Al-4V/HA parts with an open porosity of around 50% were developed.

  7. Hydrogen attack in Cr-Mo steels. [3Cr-1. 5Mo and 2. 25Cr-1Mo steels

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

    Ruoff, S.; Stone, D.; Wanagel, J.

    Experiments conducted upon 3Cr-1.5Mo steel at elevated temperatures (600 C), and high pressure hydrogen (2000 psi), have shown a greater resistence to hydrogen attack compared with similar studies of 2.25Cr-lMo steels. Hydrogen exposure tests with and without an applied stress have been performed on both types of steels. Results of similar conditions show clear evidence of hydrogen attack in 2.25Cr-lMo steel, however, for the 3Cr-1.5Mo steel with exposure time up to 80 days without an applied stress no evidence of hydrogen attack is observed. For stress-rupture tests using stresses of 14 and 16 ksi, the 3Cr-1.5Mo steel showed no effectsmore » of hydrogen attack, and no damage was observed using a SEM.« less

  8. Magnesium dititanate (MgTi2O5) with pseudobrookite structure: a review.

    PubMed

    Suzuki, Yoshikazu; Shinoda, Yutaka

    2011-06-01

    Magnesium dititanate (MgTi 2 O 5 , MT 2 ) has been synthesized since the early 1930s. It has the pseudobrookite structure (general formula Me 3 O 5 ), corresponding to the Mg-enriched artificial endmember of the Fe 2 TiO 5 (pseudobrookite)-FeTi 2 O 5 (ferropseudobrookite)-Mg 0.5 Fe 0.5 Ti 2 O 5 (armalcolite) solid solution. Since MgTi 2 O 5 has relativity high thermal stability among pseudobrookite-type phases, it is expected to be a well-balanced low-thermal-expansion material. Here we review both the historical and recent studies on MgTi 2 O 5 , particularly on its crystal structure, cation order-disorder, physical properties and synthesis methods.

  9. Photoelectrochemical Performance of TiO2/Ti Electrode for Organic Compounds

    NASA Astrophysics Data System (ADS)

    Maulidiyah, M.; Wijawan, I. B. P.; Wibowo, D.; Aladin, A.; Hamzah, B.; Nurdin, M.

    2018-05-01

    Photoelectrochemical performance of TiO2/Ti electrode was investigated by using organic compounds. The TiO2/Ti electrode was prepared by anodic oxidation at a potential bias of 25 V for 4 h then calcined for 450 °C to obtain the anatase polymorph. Subsequently, it was characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX). The XRD pattern showed that TiO2 has anatase phase as confirmed by 2θ peaks at 37.93° 63.00°, and 83.00°. Using SEM-EDX data the TiO2 layer was formed on Ti plate with the composition of Ti (4.5 keV) and O (0.5 keV) elements. Furthermore, the photoelectrochemical sensing on the three organic compounds (ascorbic acid, glucose, and titan yellow) with the electrolyte addition showed that the linearity of TiO2/Ti electrode were 0.937, 0.968, and 0.938, meanwhile without the electrolyte were 0.998, 0.989, and 0.923, respectively.

  10. Incubation of cocaine cue reactivity associates with neuroadaptations in the cortical serotonin (5-HT) 5-HT2C receptor (5-HT2CR) system

    PubMed Central

    Swinford-Jackson, Sarah E.; Anastasio, Noelle C.; Fox, Robert G.; Stutz, Sonja J.; Cunningham, Kathryn A.

    2016-01-01

    Intensification of craving elicited by drug-associated cues during abstinence occurs over time in human cocaine users while elevation of cue reactivity (“incubation”) is observed in rats exposed to extended forced abstinence from cocaine self-administration. Incubation in rodents has been linked to time-dependent neuronal plasticity in the medial prefrontal cortex (mPFC). We tested the hypothesis that incubation of cue reactivity during abstinence from cocaine self-administration is accompanied by lower potency and/or efficacy of the selective 5-HT2CR agonist WAY163909 to suppress cue reactivity and a shift in the subcellular localization profile of the mPFC 5-HT2CR protein. We observed incubation of cue reactivity (measured as lever presses reinforced by the discrete cue complex) between Day 1 and Day 30 of forced abstinence from cocaine relative to sucrose self-administration. Pharmacological and biochemical analyses revealed that the potency of the selective 5-HT2CR agonist WAY163909 to suppress cue reactivity, the expression of synaptosomal 5-HT2CR protein in the mPFC, and the membrane to cytoplasmic expression of the 5-HT2CR in mPFC were lower on Day 30 vs. Day 1 of forced abstinence from cocaine self-administration. Incubation of cue reactivity assessed during forced abstinence from sucrose self-administration did not associate with 5-HT2CR protein expression in the mPFC. Collectively, these outcomes are the first indication that neuroadaptations in the 5-HT2CR system may contribute to incubation of cocaine cue reactivity. PMID:26926963

  11. Wear Behavior of Plasma Spray Deposited and Post Heat-Treated Hydroxyapatite (HA)-Based Composite Coating on Titanium Alloy (Ti-6Al-4V) Substrate

    NASA Astrophysics Data System (ADS)

    Kumari, Renu; Majumdar, Jyotsna Dutta

    2018-04-01

    The present study concerns a detailed evaluation of wear resistance property of plasma spray deposited composite hydroxyapatite (HA)-based (HA-50 wt pct TiO2 and HA-10 wt pct ZrO2) bioactive coatings developed on Ti-6Al-4V substrate and studying the effect of heat treatment on it. Heat treatment of plasma spray deposited samples has been carried out at 650 °C for 2 hours (for HA-50 wt pct TiO2 coating) and at 750 °C for 2 hours (for HA-10 wt pct ZrO2 coating). There is significant deterioration in wear resistance for HA-50 wt pctTiO2 coating and a marginal deterioration in wear resistance for HA-10 wt pct ZrO2 coating in as-sprayed state (as compared to as-received Ti-6Al-4V) which is, however, improved after heat treatment. The coefficient of friction is marginally increased for both HA-50 wt pct TiO2 and HA-10 wt pct ZrO2 coatings in as-sprayed condition as compared to Ti-6Al-4V substrate. However, coefficient of friction is decreased for both HA-50 wt pct TiO2 and HA-10 wt pct ZrO2 coatings after heat-treated condition as compared to Ti-6Al-4V substrate. The maximum improvement in wear resistance property is, however, observed for HA-10 wt pct ZrO2 sample after heat treatment. The mechanism of wear has been investigated.

  12. 75 FR 12971 - Airworthiness Directives; International Aero Engines (IAE) V2500-A1, V2522-A5, V2524-A5, V2525-D5...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-18

    ... could result in an uncontained failure of the high-pressure (HP) compressor stage 3-8 drum and..., V2527M-A5, V2528-D5, V2530-A5, and V2533-A5 turbofan engines with high-pressure (HP) compressor stage 3-8...

  13. Mechanical Properties of β-Ti-35Nb-2.5Sn Alloy Synthesized by Mechanical Alloying and Pulsed Current Activated Sintering

    NASA Astrophysics Data System (ADS)

    Omran, Abdel-Nasser; Woo, Kee-Do; Lee, Hyun Bom

    2012-12-01

    A developed Ti-35 pct Nb-2.5 pct Sn (wt pct) alloy was synthesized by mechanical alloying using high-energy ball-milled powders, and the powder consolidation was done by pulsed current activated sintering (PCAS). The starting powder materials were mixed for 24 hours and then milled by high-energy ball milling (HEBM) for 1, 4, and 12 hours. The bulk solid samples were fabricated by PCAS at 1073 K to 1373 K (800 °C to 1100 °C) for a short time, followed by rapid cooling to 773 K (500 °C). The relative density of the sintered samples was about 93 pct. The Ti was completely transformed from α to β-Ti phase after milling for 12 hours in powder state, and the specimen sintered at 1546 K (1273 °C) was almost transformed to β-Ti phase. The homogeneity of the sintered specimen increased with increasing milling time and sintering temperature, as did its hardness, reaching 400 HV after 12 hours of milling. The Young's modulus was almost constant for all sintered Ti-35 pct Nb-2.5 pct Sn specimens at different milling times. The Young's modulus was low (63.55 to 65.3 GPa) compared to that of the standard alloy of Ti-6Al-4V (100 GPa). The wear resistance of the sintered specimen increased with increasing milling time. The 12-hour milled powder exhibited the best wear resistance.

  14. Evaluating electrically insulating films deposited on V-4% Cr-4% Ti by reactive CVD

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

    Park, J.H.; Cho, W.D.

    1997-04-01

    Previous CaO coatings on V-4%Cr-4%Ti exhibited high-ohmic insulator behavior even though a small amount of vanadium from the alloy was incorporated in the coating. However, when the vanadium concentration in the coatings is > 15 wt%, the coating becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. To explore this situation, CaO and Ca-V-O coatings were produced on vanadium alloys by chemical vapor deposition (CVD) and by a metallic-vapor process to investigate the electrical resistance of the coatings. Initially, the vanadium alloy specimens were either charged with oxygenmore » in argon that contained trace levels of oxygen, or oxidized for 1.5-3 h in a 1% CO-CO{sub 2} gas mixture or in air to form vanadium oxide at 625-650{degrees}C. Most of the specimens were exposed to calcium vapor at 800-850{degrees}C. Initial and final weights were obtained to monitor each step, and surveillance samples were removed for examination by optical and scanning electron microscopy and electron-energy-dispersive and X-ray diffraction analysis; the electrical resistivity was also measured. The authors found that Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film was > 0.9, and semiconductor or conductor behavior for R < 0.8. However, in some cases, semiconductor behavior was observed when CaO-coated samples with R > 0.98 were exposed in liquid lithium. Based on these studies, the authors conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating.« less

  15. TI--CR--AL--O thin film resistors

    DOEpatents

    Jankowski, Alan F.; Schmid, Anthony P.

    2000-01-01

    Thin films of Ti--Cr--Al--O are used as a resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O.sub.2. Resistivity values from 10.sup.4 to 10.sup.10 Ohm-cm have been measured for Ti--Cr--Al--O film <1 .mu.m thick. The film resistivity can be discretely selected through control of the target composition and the deposition parameters. The application of Ti--Cr--Al--O as a thin film resistor has been found to be thermodynamically stable, unlike other metal-oxide films. The Ti--Cr--Al--O film can be used as a vertical or lateral resistor, for example, as a layer beneath a field emission cathode in a flat panel display; or used to control surface emissivity, for example, as a coating on an insulating material such as vertical wall supports in flat panel displays.

  16. Orientation Dependence of Functional Properties in Heterophase Single Crystals of the Ti36.5Ni51.0Hf12.5 and Ti48.5Ni51.5 Alloys

    NASA Astrophysics Data System (ADS)

    Panchenko, E. Yu.; Chumlyakov, Yu. I.; Surikov, N. Yu.; Tagiltsev, A. I.; Vetoshkina, N. G.; Osipovich, K. S.; Maier, H.; Sehitoglu, H.

    2016-03-01

    The features of orientation dependence of stress-induced thermoelastic B2-( R)- B19'-martensitic transformations in single crystals of the Ti48.5Ni51.5 and Ni51.0Ti36.5Hf12.5 (at.%) alloys, which contain disperse particles of the Ti3Ni4 and H-phase, respectively, are revealed along with those of their shape-memory effects (SME) and superelasticity (SE). It is experimentally demonstrated that irrespective of the crystal structure of disperse particles measuring more than 100 nm, for their volume fraction f > 16% there is a weaker orientation dependence of the reversible strain in the cases of manifestation of SME and SE. In the orientations of Class I, wherein martensitic detwinning introduces a considerable contribution into transformation strain, the values of SME |ɛ SME | and SE |ɛ SE | decrease by over a factor of two compared to the theoretical lattice strain value |ɛ tr0 | for a B2- B19'-transformation and the experimental values of reversible strain for quenched TiNi crystals. In the orientations of Class 2, wherein detwinning of the martensite is suppressed as is the case in quenched single-phase single crystals, the reversible strain is maintained close to its theoretical value |ɛ tr0 |. Micromechanical models of interaction between the martensite and the disperse particles are proposed, which account for the weaker orientation dependence of |ɛ SME | and |ɛ SE | due to suppression of detwinning of the B19'-martensite crystals by the particles and a transition from a single-variant evolution of the stress-induced martensitic transformations to a multiple-variant evolution of transformations in the cases of increased size of the particles and their larger volume fractions.

  17. Energy efficient microwave synthesis of mesoporous Ce 0.5M 0.5O 2 (Ti, Zr, Hf) nanoparticles for low temperature CO oxidation in an ionic liquid – a comparative study

    DOE PAGES

    Alammar, Tarek; Chow, Ying -Kit; Mudring, Anja -Verena

    2014-11-19

    Ce 0.5M 0.5O 2 (M = Ti, Zr, Hf) nanoparticles have been successfully synthesized by microwave irradiation in the ionic liquid [C 4mim][Tf 2N] (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide). The morphology, crystallinity, and chemical composition of the obtained materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and N 2–adsorption measurements. XRD and Raman spectroscopy analyses confirmed the formation of solid solutions with cubic fluorite structure. The catalytic activities of the Ce 0.5M 0.5O 2 (M = Ti, Zr, Hf) nanoparticles were investigated in the low-temperature oxidation of CO. Ce 0.5Zr 0.5O 2 nanospheresmore » exhibit the best performance (100% conversion at 350 °C), followed by Ce 0.5Hf 0.5O 2 (55% conversion at 360 °C) and Ce 0.5Ti 0.5O 2 (11% conversion at 350 °C). Heating the as-prepared Ce 0.5Zr 0.5O 2 to 600 °C for extended time leads to a decrease in surface area and, as expected decreased catalytic activity. Depending on the ionic liquid the obtained Ce 0.5Zr 0.5O 2 exhibits different morphologies, varying from nano-spheres in [C 4mim][Tf 2N] and [P 66614][Tf 2N] (P 66614 = trishexyltetradecylphosphonium) to sheet-like assemblies in [C 3mimOH][Tf 2N] (C 3mimOH = 1-(3-hydroxypropyl)-3-methylimidazolium). As a result, the microwave synthesis superiority to other heating methods like sonochemical synthesis and conventional heating was proven by comparative experiments where the catalytic activity of Ce 0.5Zr 0.5O 2 obtained by alternate methods such as conventional heating was found to be poorer than that of the microwave-synthesised material.« less

  18. Inducing Stable α + β Microstructures during Selective Laser Melting of Ti-6Al-4V Using Intensified Intrinsic Heat Treatments

    PubMed Central

    Barriobero-Vila, Pere; Gussone, Joachim; Haubrich, Jan; Sandlöbes, Stefanie; Da Silva, Julio Cesar; Cloetens, Peter; Schell, Norbert; Requena, Guillermo

    2017-01-01

    Selective laser melting is a promising powder-bed-based additive manufacturing technique for titanium alloys: near net-shaped metallic components can be produced with high resource-efficiency and cost savings. For the most commercialized titanium alloy, namely Ti-6Al-4V, the complicated thermal profile of selective laser melting manufacturing (sharp cycles of steep heating and cooling rates) usually hinders manufacturing of components in a one-step process owing to the formation of brittle martensitic microstructures unsuitable for structural applications. In this work, an intensified intrinsic heat treatment is applied during selective laser melting of Ti-6Al-4V powder using a scanning strategy that combines porosity-optimized processing with a very tight hatch distance. Extensive martensite decomposition providing a uniform, fine lamellar α + β microstructure is obtained along the building direction. Moreover, structural evidence of the formation of the intermetallic α2-Ti3Al phase is provided. Variations in the lattice parameter of β serve as an indicator of the microstructural degree of stabilization. Interconnected 3D networks of β are generated in regions highly affected by the intensified intrinsic heat treatment applied. The results obtained reflect a contribution towards simultaneous selective laser melting-manufacturing and heat treatment for fabrication of Ti-6Al-4V parts. PMID:28772630

  19. Nodeless superconductivity and time-reversal symmetry breaking in the noncentrosymmetric superconductor Re24Ti5

    NASA Astrophysics Data System (ADS)

    Shang, T.; Pang, G. M.; Baines, C.; Jiang, W. B.; Xie, W.; Wang, A.; Medarde, M.; Pomjakushina, E.; Shi, M.; Mesot, J.; Yuan, H. Q.; Shiroka, T.

    2018-01-01

    The noncentrosymmetric superconductor Re24Ti5 , a time-reversal symmetry- (TRS-) breaking candidate with Tc=6 K , was studied by means of muon-spin rotation/relaxation (μ SR ) and tunnel-diode oscillator techniques. At the macroscopic level, its bulk superconductivity was investigated via electrical resistivity, magnetic susceptibility, and heat-capacity measurements. The low-temperature penetration depth, superfluid density, and electronic heat capacity all evidence an s -wave coupling with an enhanced superconducting gap. The spontaneous magnetic fields revealed by zero-field μ SR below Tc indicate a time-reversal symmetry breaking and thus the unconventional nature of superconductivity in Re24Ti5 . The concomitant occurrence of TRS breaking also in the isostructural Re6(Zr ,Hf ) compounds hints at its common origin in this superconducting family and that an enhanced spin-orbital coupling does not affect pairing symmetry.

  20. Structure and energetics of Cr(CO)6 and Cr(CO)5

    NASA Technical Reports Server (NTRS)

    Barnes, Leslie A.; Liu, Bowen; Lindh, Roland

    1993-01-01

    The geometric structures and energetics of Cr(CO)6 and Cr(CO)5 are determined at the modified coupled-pair functional, single and double excitation coupled-cluster (CCSD), and CCSD(T) levels of theory. For Cr(CO)6, the structure and force constants for the totally symmetric representation are in good agreement with experimental data once basis set constants are taken into account. In the largest basis set at the CCSD(T) level of theory, the total binding energy of CR(CO)6 is estimated at around 140 kcal/mol, or about 86 percent of the experimental value. In contrast, the first bond energy of Cr(CO)6 is very well described at the CCSD(T) level of theory, with the best estimated value of 38 kcal/mol being within the experimental uncertainty.

  1. Synthesis and magnetotransport studies of CrO2 films grown on TiO2 nanotube arrays by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoling; Zhang, Caiping; Wang, Lu; Lin, Tao; Wen, Gehui

    2018-04-01

    The CrO2 films have been prepared on the TiO2 nanotube array template via atmospheric pressure chemical vapor deposition method. And the growth procedure was studied. In the beginning of the deposition process, the CrO2 grows on the cross section of the TiO2 nanotubes wall, forms a nanonet-like layer. And the grain size of CrO2 is very small. With the increase of the deposition time, the grain size of CrO2 also increases, and the nanonet-like layer changes into porous film. With the further increase of the deposition time, all the nanotubes are covered by CrO2 grains and the surface structure becomes polycrystalline film. The average grain size on the surface of the CrO2 films deposited for 1 h, 2 h and 5 h is about 190 nm, 300 nm and 470 nm. The X-ray diffraction pattern reveals that the rutile CrO2 film has been synthesized on the TiO2 nanotube array template. The CrO2 films show large magnetoresistance (MR) at low temperature, which should originate from spin-dependent tunneling through grain boundaries between CrO2 grains. And the tunneling mechanism of the CrO2 films can be well described by the fluctuation-induced tunneling (FIT) model. The CrO2 film deposited for 2 h shows insulator behavior from 5 k to 300 K, but the CrO2 film deposited for 5 h shows insulator-metal transition around 140 K. The reason is briefly discussed.

  2. Study on the decomposition of trace benzene over V2O5-WO3/TiO2-based catalysts in simulated flue gas

    EPA Science Inventory

    Commercial and laboratory-prepared V2O5–WO3/TiO2-based catalysts with different compositions were tested for catalytic decomposition of chlorobenzene (ClBz) in simulated flue gas. Resonance enhanced multiphoton ionization-time of flight mass spectrometry (REMPI-TOFMS) was employe...

  3. Formation of Equiaxed Alpha and Titanium Nitride Precipitates in Spark Plasma Sintered TiB/Ti-6Al-4V Composites (Preprint)

    DTIC Science & Technology

    2012-08-01

    AFRL-RX-WP-TP-2012-0372 FORMATION OF EQUIAXED ALPHA AND TITANIUM NITRIDE PRECIPITATES IN SPARK PLASMA SINTERED TiB/Ti-6Al-4V COMPOSITES...ALPHA AND TITANIUM NITRIDE PRECIPITATES IN SPARK PLASMA SINTERED TiB/Ti-6Al-4V COMPOSITES (PREPRINT) 5a. CONTRACT NUMBER FA8650-08-C-5226 5b...distribution of TiN precipitates, as revealed by TEM studies. 15. SUBJECT TERMS Ti-6Al-4V; TiB; TiN; Spark Plasma Sintering ; Composite; α/β phase

  4. An Analysis of Light Periods of BL Lac Object S5 0716+714 with the MUSIC Algorithm

    NASA Astrophysics Data System (ADS)

    Tang, Jie

    2012-07-01

    The multiple signal classification (MUSIC) algorithm is introduced to the estimation of light periods of BL Lac objects. The principle of the MUSIC algorithm is given, together with a testing on its spectral resolution by using a simulative signal. From a lot of literature, we have collected a large number of effective observational data of the BL Lac object S5 0716+714 in the three optical wavebands V, R, and I from 1994 to 2008. The light periods of S5 0716+714 are obtained by means of the MUSIC algorithm and average periodogram algorithm, respectively. It is found that there exist two major periodic components, one is the period of (3.33±0.08) yr, another is the period of (1.24±0.01) yr. The comparison of the performances of periodicity analysis of two algorithms indicates that the MUSIC algorithm has a smaller requirement on the sample length, as well as a good spectral resolution and anti-noise ability, to improve the accuracy of periodicity analysis in the case of short sample length.

  5. Cross-Plane Seebeck Coefficient Measurement of Misfit Layered Compounds (SnSe)n(TiSe2)n (n = 1,3,4,5).

    PubMed

    Li, Zhen; Bauers, Sage R; Poudel, Nirakar; Hamann, Danielle; Wang, Xiaoming; Choi, David S; Esfarjani, Keivan; Shi, Li; Johnson, David C; Cronin, Stephen B

    2017-03-08

    We report cross-plane thermoelectric measurements of misfit layered compounds (SnSe) n (TiSe 2 ) n (n = 1,3,4,5), approximately 50 nm thick. Metal resistance thermometers are fabricated on the top and bottom of the (SnSe) n (TiSe 2 ) n material to measure the temperature difference and heat transport through the material directly. By varying the number of layers in a supercell, n, we vary the interface density while maintaining a constant global stoichiometry. The Seebeck coefficient measured across the (SnSe) n (TiSe 2 ) n samples was found to depend strongly on the number of layers in the supercell (n). When n decreases from 5 to 1, the cross-plane Seebeck coefficient decreases from -31 to -2.5 μV/K, while the cross-plane effective thermal conductivity decreases by a factor of 2, due to increased interfacial phonon scattering. The cross-plane Seebeck coefficients of the (SnSe) n (TiSe 2 ) n are very different from the in-plane Seebeck coefficients, which are higher in magnitude and less sensitive to the number of layers in a supercell, n. We believe this difference is due to the different carrier types in the n-SnSe and p-TiSe 2 layers and the effect of tunneling on the cross-plane transport.

  6. Structural, magnetic, and dielectric studies of the Aurivillius compounds SrBi{sub 5}Ti{sub 4}MnO{sub 18} and SrBi{sub 5}Ti{sub 4}Mn{sub 0.5}Co{sub 0.5}O{sub 18}

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

    Yuan, B.; Yang, J., E-mail: jyang@issp.ac.cn; Zuo, X. Z.

    We have successfully synthesized the Aurivillius compounds SrBi{sub 5}Ti{sub 4}MnO{sub 18} and SrBi{sub 5}Ti{sub 4}Mn{sub 0.5}Co{sub 0.5}O{sub 18} using a modified Pechini method. Both samples have an orthorhombic structure with the space group B2cb. The valence state of Mn is suggested to be +3 and the doped Co ions exist in the form of Co{sup 2+} and Co{sup 3+} based on the results of x-ray photoelectron spectroscopy. The sample SrBi{sub 5}Ti{sub 4}MnO{sub 18} exhibits a dominant paramagnetic state with the existence of superparamagnetic state as evidenced by the electron paramagnetic resonance results, whereas SrBi{sub 5}Ti{sub 4}Mn{sub 0.5}Co{sub 0.5}O{sub 18} undergoesmore » a ferrimagnetic transition at 161 K originating from the antiferromagnetic coupling of Co-based and Mn-based sublattices, and a ferromagnetic transition at 45 K arising from the Mn{sup 3+}-O-Co{sup 3+} (low spin) interaction. The sample SrBi{sub 5}Ti{sub 4}Mn{sub 0.5}Co{sub 0.5}O{sub 18} exhibits two dielectric anomalies. One corresponds to a relaxor-like dielectric relaxation which follows the Vogel-Fulcher function and the other dielectric relaxation obeys the Arrhenius law arising from the collective motion of oxygen vacancies. In addition, the sample SrBi{sub 5}Ti{sub 4}Mn{sub 0.5}Co{sub 0.5}O{sub 18} exhibits a magnetodielectric effect caused by the Maxwell-Wagner effect because of the conductivity of the sample. This is demonstrated by the fact that the activation energy in dielectric loss process is close to that for dc conductivity and the magnetodielectric effect is sensitive to the measured frequency.« less

  7. Design of Nickel-Based Cation-Disordered Rock-Salt Oxides: The Effect of Transition Metal (M = V, Ti, Zr) Substitution in LiNi0.5M0.5O2 Binary Systems.

    PubMed

    Cambaz, Musa Ali; Vinayan, Bhaghavathi P; Euchner, Holger; Johnsen, Rune E; Guda, Alexander A; Mazilkin, Andrey; Rusalev, Yury V; Trigub, Alexander L; Gross, Axel; Fichtner, Maximilian

    2018-06-20

    Cation-disordered oxides have been ignored as positive electrode material for a long time due to structurally limited lithium insertion/extraction capabilities. In this work, a case study is carried out on nickel-based cation-disordered Fm3 ̅m LiNi 0.5 M 0.5 O 2 positive electrode materials. The present investigation targets tailoring the electrochemical properties for nickel-based cation-disordered rock-salt by electronic considerations. The compositional space for binary LiM +3 O 2 with metals active for +3/+4 redox couples is extended to ternary oxides with LiA 0.5 B 0.5 O 2 with A = Ni 2+ and B = Ti 4+ , Zr 4+ , and V +4 to assess the impact of the different transition metals in the isostructural oxides. The direct synthesis of various new unknown ternary nickel-based Fm3̅ m cation-disordered rock-salt positive electrode materials is presented with a particular focus on the LiNi 0.5 V 0.5 O 2 system. This positive electrode material for Li-ion batteries displays an average voltage of ∼2.55 V and a high discharge capacity of 264 mAhg -1 corresponding to 0.94 Li. For appropriate cutoff voltages, a long cycle life is achieved. The charge compensation mechanism is probed by XANES, confirming the reversible oxidation and reduction of V 4+ /V 5+ . The enhancement in the electrochemical performances within the presented compounds stresses the importance of mixed cation-disordered transition metal oxides with different electronic configuration.

  8. Durability of Ti-6Al-4V/LaRC-PETI-5 adhesive bonded system for HSCT applications

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

    Parvatareddy, H.; Pasricha, A.; Dillard, D.A.

    1996-12-31

    Structural adhesive joints are being widely used and studied as alternatives to conventional fasteners in the aerospace, automotive, and other industries. Adhesive bonding offers advantages such as lower weight and lower manufacturing costs. Furthermore, high performance adhesives which are currently being synthesized (e.g. epoxies, phenolics, acrylics, thermoplastic polyimides) offer other useful properties such as higher modulus, higher toughness, and stability at high temperatures. In the present study, the durability of the Ti-6Al-4V/LaRC PETI-5 adhesive bonded system is being evaluated utilizing double cantilever beam (DCB) fracture specimens. These DCB tests have been used extensively to study adhesive joints. The current studymore » is part of a comprehensive study to develop a durable material system for application in the proposed mach 2.4 high speed civil transport (HSCT) aircraft. According to the design criteria, the material system to be used on the aircraft should be durable for over 60,000 hours of flight encountering temperatures during flight in the range of 177{degrees}C. Physical aging and chemical aging of the adhesive material are some of the important issues which have to be evaluated and taken into consideration for predicting the bond durability. In order to simulate the service environment conditions of the HSCT, the Ti-6Al-4V/LaRC PETI-5 bonds were aged in one of three temperatures; 150, 177, and 204{degrees}C, at one of three different environments; atmospheric air, and reduced air pressures of 2 psi air (13.8 KPa) and 0.2 psi air (1.38 KPa).« less

  9. Fabrication of the Ti5Si3/Ti composite inoculants and its refining mechanism on pure titanium

    NASA Astrophysics Data System (ADS)

    Li, Nuo; Cui, Chunxiang; Liu, Shaungjin; Zhao, Long; Liu, Shuiqing

    2017-03-01

    The in situ Ti5Si3/Ti inoculants were successfully prepared by vacuum arc-melting and melt-spinning method. An efficient route by adding a small quantity of Ti5Si3/Ti inoculants to Ti melt has been first proposed to modify the coarse grains of as cast microstructure of pure titanium in this paper. It was found that the microstructure of ribbon inoculants was cellular structure that composed of Ti5Si3 and α-Ti phases. The grain refining effect of the inoculants was significantly improved with the adding ratio range from 0.2% to 0.5% in weight. With the increase of addition amount of inoculants on Ti melt, the tensile strength, yield strength and microhardness of pure titanium are significantly improved except elongation. The excellent grain refining effect can be attributed to the heterogeneous nucleation of the titanium grain on the precipitated Ti5Si3 phases in the Si-rich regions and the constitutional supercooling of Si in the Si-poverty regions. It is suggested that the in situ Ti5Si3/Ti inoculants is a promising inoculants for titanium alloys.

  10. Effects of transition metal doping in Pt/M-TiO2 (M = V, Cr, and Nb) on oxygen reduction reaction activity

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

    Kim, Jun-Hyuk; Kwon, Gihan; Lim, Hankwon

    High cost and low durability are unresolved issues that impede the commercialization of proton exchange membrane fuel cells (PEMFCs). To overcome these limitations, Pt/TiO2 is reported as an alternative electrocatalyst for enhancing the oxygen reduction reaction (ORR) activity and/or durability of the system. However, the low electrical conductivity of TiO2 is a drawback that may be addressed by doping. To date, most reports related to Pt/doped-TiO2 focus on changes in the catalyst activity caused by the Pt-TiO2 interaction (metal -support interaction), instead of the effect of doping itself; doping is merely considered to enhance the electrical conductivity of TiO2. Inmore » this study, we discuss the variation in the electronic fine structure of Pt caused by the dopant, and its correlation with the ORR activity. More extensive contraction of the Pt lattice in Pt/M-TiO2 (M = V, Cr, and Nb) relative to Pt/TiO2 and Pt/C leads to outstanding ORR specific activity of Pt/M-TiO2. Notably, a fourfold increase of the specific activity is achieved with Pt/V-TiO2 relative to Pt/C. Furthermore, an accelerated durability test (ADT) of Pt/V-TiO2 demonstrates that this system is three times more durable than conventional Pt/C due to the metal support interaction.« less

  11. Temperature-dependent electron paramagnetic resonance detect oxygen vacancy defects and Cr valence of tetragonal Ba(Ti1-xCrx)O3 ceramics

    NASA Astrophysics Data System (ADS)

    Han, Dan-Dan; Lu, Da-Yong; Meng, Fan-Ling; Yu, Xin-Yu

    2018-03-01

    Temperature-dependent electron paramagnetic resonance (EPR) study was employed to detect oxygen vacancy defects in the tetragonal Ba(Ti1-xCrx)O3 (x = 5%) ceramic for the first time. In the rhombohedral phase below -150 °C, an EPR signal at g = 1.955 appeared in the insulating Ba(Ti1-xCrx)O3 (x = 5%) ceramic with an electrical resistivity of 108 Ω cm and was assigned to ionized oxygen vacancy defects. Ba(Ti1-xCrx)O3 ceramics exhibited a tetragonal structure except Ba(Ti1-xCrx)O3 (x = 10%) with a tetragonal-hexagonal mixed phase and a first-order phase transition dielectric behavior (ε‧m > 11,000). Mixed valence Cr ions could coexist in ceramics, form CrTi‧-VOrad rad or CrTirad-TiTi‧ defect complexes and make no contribution to a dielectric peak shift towards low temperature.

  12. Structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds

    NASA Astrophysics Data System (ADS)

    Liu, Yangzhen; Xing, Jiandong; Fu, Hanguang; Li, Yefei; Sun, Liang; Lv, Zheng

    2017-08-01

    The properties of sulfides are important in the design of new iron-steel materials. In this study, first-principles calculations were used to estimate the structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds. The results reveal that these XS binary compounds are thermodynamically stable, because their formation enthalpy is negative. The elastic constants, Cij, and moduli (B, G, E) were investigated using stress-strain and Voigt-Reuss-Hill approximation, respectively. The sulfide anisotropy was discussed from an anisotropic index and three-dimensional surface contours. The electronic structures reveal that the bonding characteristics of the XS compounds are a mixture of metallic and covalent bonds. Using a quasi-harmonic Debye approximation, the heat capacity at constant pressure and constant volume was estimated. NiS possesses the largest CP and CV of the sulfides.

  13. Epitaxial Ferroelectric Ba(0.5)Sr(0.5)TiO3 Thin Films for Room-Temperature High-Frequency Tunable Element Applications

    NASA Technical Reports Server (NTRS)

    Chen, C. L.; Feng, H. H.; Zhang, Z.; Brazdeikis, A.; Miranda, F. A.; VanKeuls, F. W.; Romanofsky, R. R.; Huang, Z. J.; Liou, Y.; Chu, W. K.; hide

    1999-01-01

    Perovskite Ba(0.5)SR(0.5)TiO3 thin films have been synthesized on (001) LaAl03 substrates by pulsed laser ablation. Extensive X-ray diffraction, rocking curve, and pole-figure studies suggest that the films are c-axis oriented and exhibit good in-plane relationship of <100>(sub BSTO)//<100>(sub LAO). Rutherford Backscattering Spectrometry studies indicate that the epitaxial films have excellent crystalline quality with an ion beam minimum yield chi(sub min) Of only 2.6 %. The dielectric property measurements by the interdigital technique at 1 MHz show room temperature values of the relative dielectric constant, epsilon(sub r), and loss tangent, tan(sub delta), of 1430 and 0.007 with no bias, and 960 and 0.001 with 35 V bias, respectively. The obtained data suggest that the as-grown Ba(0.5)SR(0.5)TiO3 films can be used for development of room-temperature high-frequency tunable elements.

  14. POWERFUL HIGH-ENERGY EMISSION OF THE REMARKABLE BL Lac OBJECT S5 0716+714

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

    Vittorini, V.; Chen, A. W.; Ferrari, A.

    BL Lac objects of the intermediate subclass (IBLs) are known to emit a substantial fraction of their power in the energy range 0.1-10 GeV. Detecting gamma-ray emission from such sources provides therefore a direct probe of the emission mechanisms and of the underlying powerhouse. The gamma-ray satellite, AGILE, detected the remarkable IBL S5 0716+714 (z approx = 0.3) during a high state in the period from 2007 September-October, marked by two very intense flares reaching peak fluxes of 200 x 10{sup -8} photons cm{sup -2} s{sup -1} above 100 MeV, with simultaneous optical and X-ray observations. We present here amore » theoretical model for the two major flares and discuss the overall energetics of the source. We conclude that 0716+714 is among the brightest BL Lac's ever detected at gamma-ray energies. Because of its high power and lack of signs for ongoing accretion or surrounding gas, the source is an ideal candidate to test the maximal power extractable from a rotating supermassive black hole via the pure Blandford-Znajek (BZ) mechanism. We find that during the 2007 gamma-ray flares 0716+714 approached or just exceeded the upper limit set by BZ for a black hole of mass 10{sup 9} M{sub sun}.« less

  15. 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.

  16. A novel drug delivery of 5-fluorouracil device based on TiO2/ZnS nanotubes.

    PubMed

    Faria, Henrique Antonio Mendonça; de Queiroz, Alvaro Antonio Alencar

    2015-11-01

    The structural and electronic properties of titanium oxide nanotubes (TiO2) have attracted considerable attention for the development of therapeutic devices and imaging probes for nanomedicine. However, the fluorescence response of TiO2 has typically been within ultraviolet spectrum. In this study, the surface modification of TiO2 nanotubes with ZnS quantum dots was found to produce a red shift in the ultra violet emission band. The TiO2 nanotubes used in this work were obtained by sol-gel template synthesis. The ZnS quantum dots were deposited onto TiO2 nanotube surface by a micelle-template inducing reaction. The structure and morphology of the resulting hybrid TiO2/ZnS nanotubes were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. According to the results of fluorescence spectroscopy, pure TiO2 nanotubes exhibited a high emission at 380nm (3.26eV), whereas TiO2/ZnS exhibited an emission at 410nm (3.02eV). The TiO2/ZnS nanotubes demonstrated good bio-imaging ability on sycamore cultured plant cells. The biocompatibility against mammalian cells (Chinese Hamster Ovarian Cells-CHO) suggesting that TiO2/ZnS may also have suitable optical properties for use as biological markers in diagnostic medicine. The drug release characteristic of TiO2/ZnS nanotubes was explored using 5-fluorouracil (5-FU), an anticancer drug used in photodynamic therapy. The results show that the TiO2/ZnS nanotubes are a promising candidate for anticancer drug delivery systems. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Influence of TiO2 hollow sphere size on its photo-reduction activity for toxic Cr(VI) removal.

    PubMed

    Cai, Jiabai; Wu, Xueqing; Zheng, Fengying; Li, Shunxing; Wu, Yaling; Lin, Yanping; Lin, Liting; Liu, Biwen; Chen, Qiaoying; Lin, Luxiu

    2017-03-15

    After polystyrene@titanium dioxide (PS@TiO 2 ) composite with different size was calcined at designated temperature, TiO 2 hollow sphere with controllable size was obtained for high efficient photo-reduction of Cr(VI). The feature of the TiO 2 hollow sphere was investigated by SEM, TEM, XRD, UV-Vis, and photoluminescence. The photo-reduction of Cr(VI) were measured for the performance assessment of the TiO 2 hollow sphere, Cr(VI) was used as an electron acceptor. After irradiation for 2h, the photo-reduction rate of Cr(VI) (pH=2.82) for TiO 2 (450nm) was 96%, which exhibited an increase of 5% and 8% compared with TiO 2 (370nm) and TiO 2 (600nm). The absorption edges of TiO 2 hollow sphere (450nm) was largest with the increasing of hollow sphere size from 370 to 600nm. The optimal hollow sphere size of TiO 2 was 450nm for the photo-reduction of Cr(VI), because the light-harvesting efficiency (the best of absorption edge) and photo-generated electron-hole separation rate (the best of photo-reduction rate) of TiO 2 hollow sphere were controlled by its hollow sphere size. In addition, we find that the behavior of the hydrogen production was inhibited by the coexistence Cr(VI) solution. This study can improve our understanding of the mechanism for the activity enhancement by the optimal hollow sphere size of TiO 2 . Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Temperature-dependent leakage current behavior of epitaxial Bi0.5Na0.5TiO3-based thin films made by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Hejazi, M. M.; Safari, A.

    2011-11-01

    This paper discusses the electrical conduction mechanisms in a 0.88 Bi0.5Na0.5TiO3-0.08 Bi0.5K0.5TiO3-0.04 BaTiO3 thin film in the temperature range of 200-350 K. The film was deposited on a SrRuO3/SrTiO3 substrate by pulsed laser deposition technique. At all measurement temperatures, the leakage current behavior of the film matched well with the Lampert's triangle bounded by three straight lines of different slopes. The relative location of the triangle sides varied with temperature due to its effect on the density of charge carriers and un-filled traps. At low electric fields, the ohmic conduction governed the leakage mechanism. The calculated activation energy of the trap is 0.19 eV implying the presence of shallow traps in the film. With increasing the applied field, an abrupt increase in the leakage current was observed. This was attributed to a trap-filling process by the injected carriers. At sufficiently high electric fields, the leakage current obeyed the Child's trap-free square law suggesting the space charge limited current was the dominant mechanism.

  19. Measurement of the neutron-capture cross section on 63,65Cu between 0.4 and 7.5 MeV

    NASA Astrophysics Data System (ADS)

    Bray, Isabel; Bhike, Megha; Krishichayan, (None); Tornow, W.

    2015-10-01

    Copper is currently being used as a cooling and shielding material in most experimental searches for 0 ν β β decay. In order to accurately interpret background events in these experiments, the cross section of neutron-induced reactions on copper must be known. The purpose of this work was to measure the cross section of the 63,65Cu(n, γ)64,66Cu reactions. Data were collected through the activation method at a range of energies from approximately 0.4 MeV to 7.5 MeV, employing the neutron production reactions 3H(p,n)3Heand2H(d,n)3He. Previous data were limited to energies below approximately 3 MeV. The results are compared to predictions from the nuclear data libraries ENDF/B-VII.1 and TENDL-2014.

  20. Electrical properties and x-ray photoelectron spectroscopy studies of Bi(Zn0.5Ti0.5)O3 doped Pb(Zr0.4Ti0.6)O3 thin films

    NASA Astrophysics Data System (ADS)

    Tang, M. H.; Zhang, J.; Xu, X. L.; Funakubo, H.; Sugiyama, Y.; Ishiwara, H.; Li, J.

    2010-10-01

    (1-x)Pb(Zr0.4,Ti0.6)O3-(x)Bi(Zn0.5,Ti0.5)O3 (PZT-BZT) (x =0, 0.03, 0.05, 0.08, and 0.1) films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by chemical solution deposition using spin-coating. All samples showed highly (111) oriented perovskite phase and no other phase was observed. The ferroelectric properties of PZT-BZT films were systematically investigated as a function of the content x of the BZT solution. It is found that BZT doping in PZT films could greatly enhance the remnant polarization (Pr), as well as improve the fatigue property. In a 3 wt % BZT-doped PZT film, the 2Pr and the coercive field (Ec) are 90 μC/cm2 and 95 kV/cm at 10 kHz, respectively, at an electric field of 500 kV/cm, and the leakage current density is less than 1×10-7 A/cm2. The impact of BZT doping on the structure of PZT has been investigated by x-ray photoelectron spectroscopy.

  1. A sealed titanium window proportional counter for the detection of .5-keV X rays.

    NASA Technical Reports Server (NTRS)

    Mcclintock, J. E.; Levine, A.; Rappaport, S.

    1972-01-01

    A sealed Ti window proportional counter sensitive to X radiation in the energy range 0.35-0.45 keV and above 1.5 keV is described. Measurements of the Ti mass absorption coefficients and a graphical summary of the literature values are presented. For a proportional counter with a 930 microgram/sq cm (2.1-micron) Ti window, the peak efficiency at 0.45 keV is found to lie between 4.6% and 7.1%. An application in X-ray astronomy involving a rocket observation of Sco X-1 is discussed.

  2. S5 0716+714: GeV variability study

    DOE PAGES

    Rani, B.; Krichbaum, T. P.; Lott, B.; ...

    2013-02-19

    The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV–300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ~75 and ~140 days, respectively. In addition, we also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from amore » simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. Finally, we discuss several possible scenarios to explain the observed spectral break.« less

  3. S5 0716+714: GeV variability study

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

    Rani, B.; Krichbaum, T. P.; Lott, B.

    The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV–300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ~75 and ~140 days, respectively. In addition, we also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from amore » simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. Finally, we discuss several possible scenarios to explain the observed spectral break.« less

  4. THE OPTICAL MICROVARIABILITY AND SPECTRAL CHANGES OF THE BL LACERTAE OBJECT S5 0716+714

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

    Poon, H.; Fu, J. N.; Fan, J. H.

    We monitored the BL Lac object S5 0716+714 in the optical band during 2008 October and December and 2009 February with a best temporal resolution of about 5 minutes in the BVRI bands. Four fast flares were observed with amplitudes ranging from 0.3 to 0.75 mag. The source remained active during the whole monitoring campaign, showing microvariability in all days except for one. The overall variability amplitudes are {delta}B {approx} 0fm89, {delta}V {approx} 0fm80, {delta}R {approx} 0fm73, and {delta}I{approx} 0fm51. Typical timescales of microvariability range from 2 to 8 hr. The overall V - R color index ranges from 0.37more » to 0.59. Strong bluer-when-brighter chromatism was found on internight timescales. However, a different spectral behavior was found on intranight timescales. A possible time lag of {approx}11 minutes between B and I bands was found on one night. The shock-in-jet model and geometric effects can be applied to explain the source's intranight behavior.« less

  5. Effect of Thermomechanical Processing on the Microstructure, Properties, and Work Behavior of a Ti50.5 Ni29.5 Pt20 High-Temperature Shape Memory Alloy

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald; Draper, Susan; Gaydosh, Darrell; Garga, Anita; Lerch, Brad; Penney, Nicholas; Begelow, Glen; Padula, Santo, II; Brown, Jeff

    2006-01-01

    TiNiPt shape memory alloys are particularly promising for use as solid state actuators in environments up to 300 C, due to a reasonable balance of properties, including acceptable work output. However, one of the challenges to commercializing a viable high-temperature shape memory alloy (HTSMA) is to establish the appropriate primary and secondary processing techniques for fabrication of the material in a required product form such as rod and wire. Consequently, a Ti(50.5)Ni(29.5)Pt20 alloy was processed using several techniques including single-pass high-temperature extrusion, multiple-pass high-temperature extrusion, and cold drawing to produce bar stock, thin rod, and fine wire, respectively. The effects of heat treatment on the hardness, grain size, room temperature tensile properties, and transformation temperatures of hot- and cold-worked material were examined. Basic tensile properties as a function of temperature and the strain-temperature response of the alloy under constant load, for the determination of work output, were also investigated for various forms of the Ti(50.5)Ni(29.5)Pt20 alloy, including fine wire.

  6. 46 CFR 32.63-5 - Barge hull classifications-B/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Barge hull classifications-B/ALL. 32.63-5 Section 32.63..., AND HULL REQUIREMENTS Hull and Cargo Tank Requirements for Tank Barges Constructed or Converted On or After July 1, 1964, and Carrying Certain Dangerous Bulk Cargoes § 32.63-5 Barge hull classifications—B...

  7. The comparison of microstructures and mechanical properties between 14Cr-Al and 14Cr-Ti ferritic ODS alloys

    DOE PAGES

    Zhang, Guangming; Zhou, Zhangjian; Mo, Kun; ...

    2016-03-03

    In this study, two kinds of 14Cr ODS alloys (14Cr-Al and 14Cr-Ti) were investigated to reveal the different effects between Al and Ti on the microstructures and mechanical properties of 14Cr ferritic ODS alloys. The microstructure information such as grains, minor phases of these two alloys has been investigated by high-energy X-ray diffraction and transmission electron microscopy (TEM). The in situ synchrotron X-ray diffraction tensile test was applied to investigate the mechanical properties of these two alloys. The lattice strains of different phases through the entire tensile deformation process in these two alloys were analyzed to calculate their elastic stresses.more » From the comparison of elastic stress, the strengthening capability of Y 2Ti 2O 7 is better than TiN in 14Cr-Ti, and the strengthening capability of YAH is much better than YAM and AlN in 14Cr-Al ODS. The dislocation densities of 14Cr-Ti and 14Cr-Al ODS alloys during tensile deformation were also examined by modified Williamson-Hall analyses of peak broadening, respectively. In conclusion, the different increasing speed of dislocation density with plastic deformation reveals the better strengthening effect of Y-Ti-O particles in 14Cr-Ti ODS than that of Y-Al-O particles in 14Cr-Al ODS alloy.« less

  8. A Perspective on the Selective Catalytic Reduction (SCR) of NO with NH 3 by Supported V 2O 5 –WO 3/TiO 2 Catalysts

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

    Lai, Jun-Kun; Wachs, Israel E.

    We report the selective catalytic reduction (SCR) of NO x with NH 3 to harmless N 2 and H 2O plays a crucial role in reducing highly undesirable NO x acid gas emissions from large utility boilers, industrial boilers, municipal waste plants, and incinerators. The supported V 2O 5 –WO 3/TiO 2 catalysts have become the most widely used industrial catalysts for these SCR applications since introduction of this technology in the early 1970s. Lastly, this Perspective examines the current fundamental understanding and recent advances of the supported V 2O 5 –WO 3/TiO 2 catalyst system: (i) catalyst synthesis, (ii)more » molecular structures of titaniasupported vanadium and tungsten oxide species, (iii) surface acidity, (iv) catalytic active sites, (v) surface reaction intermediates, (vi) reaction mechanism, (vii) ratedetermining- step, and (viii) reaction kinetics.« less

  9. A Perspective on the Selective Catalytic Reduction (SCR) of NO with NH 3 by Supported V 2O 5 –WO 3/TiO 2 Catalysts

    DOE PAGES

    Lai, Jun-Kun; Wachs, Israel E.

    2018-06-04

    We report the selective catalytic reduction (SCR) of NO x with NH 3 to harmless N 2 and H 2O plays a crucial role in reducing highly undesirable NO x acid gas emissions from large utility boilers, industrial boilers, municipal waste plants, and incinerators. The supported V 2O 5 –WO 3/TiO 2 catalysts have become the most widely used industrial catalysts for these SCR applications since introduction of this technology in the early 1970s. Lastly, this Perspective examines the current fundamental understanding and recent advances of the supported V 2O 5 –WO 3/TiO 2 catalyst system: (i) catalyst synthesis, (ii)more » molecular structures of titaniasupported vanadium and tungsten oxide species, (iii) surface acidity, (iv) catalytic active sites, (v) surface reaction intermediates, (vi) reaction mechanism, (vii) ratedetermining- step, and (viii) reaction kinetics.« less

  10. Effects of Nb doping level on the electronic transport, photoelectric effect and magnetoresistance across La0.5Ca0.5MnO3/Nb:SrTiO3 junctions

    NASA Astrophysics Data System (ADS)

    Wang, J. F.; Jiang, Y. C.; Chen, M. G.; Gao, J.

    2013-12-01

    Heterojunctions composed of La0.5Ca0.5MnO3 and Nb doped SrTiO3 were fabricated, and the effects of the Nb doping level on their electronic transport, photoelectric effect, and magnetoresistance were investigated. A lower doping concentration of Nb led to better rectifying properties and higher open circuit voltages. The I-V curves for La0.5Ca0.5MnO3/0.7 wt. % Nb-SrTiO3 showed a negligible response to magnetic fields for all temperatures, whereas La0.5Ca0.5MnO3/0.05 wt. % Nb-SrTiO3 exhibited distinct magnetoresistance, which depended on both the bias voltage and temperature. These results are discussed with the assistance of conventional semiconductor theories.

  11. a Study on Microstructure Characteristics of IN SITU Formed TiC Reinforced Composite Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Guo, Wei; Luo, Hui

    2012-04-01

    In situ synthesized TiC reinforced composite coating was fabricated by laser cladding of Al-Ni-Cr-C powders on titanium alloys, which can greatly improve the surface performance of the substrate. In this study, the Al-Ni-Cr-C laser-cladded composite coatings have been researched by means of X-ray diffraction, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). There was a metallurgical combination between the Al-Ni-Cr-C laser-cladded coating and the Ti-6Al-4V substrate, and the micro-hardness of the Al-Ni-Cr-C laser-cladded coating was in the range of 1200-1450 HV0.2, which was 3-4 times higher than that of Ti-6Al-4V substrate. Furthermore, the reinforcement of theAl-Ni-Cr-C laser-cladded coating were mainly contributed to the action of the TiC, Ti3Al, Cr7C3, Al8Cr5 phases and the solution strengthening.

  12. A variable Ag-Cr-Oxalate channel lattice: [M(x)Ag(0.5)(-)(x)(H(2)O)(3)]@[Ag(2.5)Cr(C(2)O(4))(3)], M = K, Cs, Ag.

    PubMed

    Dean, Philip A W; Craig, Don; Dance, Ian; Russell, Vanessa; Scudder, Marcia

    2004-01-26

    Reaction of aqueous AgNO(3) with aqueous M(3)[Cr(ox)(3)] in >or=3:1 molar ratio causes the rapid growth of large, cherry-black, light-stable crystals which are not Ag(3)[Cr(ox)(3)], but [M(0.5)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)] (ox(2)(-) = oxalate, C(2)O(4)(2)(-); M = Na, K, Cs, Ag, or mixtures of Ag and a group 1 element). The structure of these crystals contains an invariant channeled framework, with composition [[Ag(2.5)Cr(ox)(3)](-)(0.5)]( infinity ), constructed with [Cr(ox)(3)] coordination units linked by Ag atoms through centrosymmetric [Cr-O(2)C(2)O(2)-Ag](2) double bridges. The framework composition [Ag(2.5)Cr(ox)(3)](-)(0.5) occurs because one Ag is located on a 2-fold axis. Within the channels there is a well-defined and ordered set of six water molecules, strongly hydrogen bonded to each other and some of the oxalate O atoms. This invariant channel plus water structure accommodates group 1 cations, and/or Ag cations, in different locations and in variable proportions, but always coordinated by channel water and some oxalate O atoms. The general formulation of these crystals is therefore [M(x)Ag(0.5-x)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)]. Five different crystals with this structure are reported, with compositions 1 Ag(0.5)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 2 Cs(0.19)Ag(0.31)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 3 K(0.28)Ag(0.22)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 4 Cs(0.41)Ag(0.09)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), and 5 Cs(0.43)Ag(0.07) [Ag(2.5)Cr(ox)(3)](H(2)O)(3). All crystallize in space group C2/c, with a approximately 18.4, b approximately 14.6, c approximately 12.3 A, beta approximately 113 degrees. Pure Ag(3)[Cr(ox)(3)](H(2)O)(3), which has the same crystal structure (1), was obtained from water by treating Li(3)[Cr(ox)(3)] with excess AgNO(3). Complete dehydration of all of these compounds occurs between 30 and 100 degrees C, with loss of diffraction, but rehydration by exposure to H(2)O(g) at ambient temperature leads to recovery of the original diffraction pattern. In single

  13. Performance Improvement of V-Fe-Cr-Ti Solid State Hydrogen Storage Materials in Impure Hydrogen Gas.

    PubMed

    Ulmer, Ulrich; Oertel, Daria; Diemant, Thomas; Bonatto Minella, Christian; Bergfeldt, Thomas; Dittmeyer, Roland; Behm, R Jürgen; Fichtner, Maximilian

    2018-01-17

    Two approaches of engineering surface structures of V-Ti-based solid solution hydrogen storage alloys are presented, which enable improved tolerance toward gaseous oxygen (O 2 ) impurities in hydrogen (H 2 ) gas. Surface modification is achieved through engineering lanthanum (La)- or nickel (Ni)-rich surface layers with enhanced cyclic stability in an H 2 /O 2 mixture. The formation of a Ni-rich surface layer does not improve the cycling stability in H 2 /O 2 mixtures. Mischmetal (Mm, a mixture of La and Ce) agglomerates are observed within the bulk and surface of the alloy when small amounts of this material are added during arc melting synthesis. These agglomerates provide hydrogen-transparent diffusion pathways into the bulk of the V-Ti-Cr-Fe hydrogen storage alloy when the remaining oxidized surface is already nontransparent for hydrogen. Thus, the cycling stability of the alloy is improved in an O 2 -containing hydrogen environment as compared to the same alloy without addition of Mm. The obtained surface-engineered storage material still absorbs hydrogen after 20 cycles in a hydrogen-oxygen mixture, while the original material is already deactivated after 4 cycles.

  14. Lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 nanowires for energy harvesting.

    PubMed

    Zhou, Zhi; Bowland, Christopher C; Malakooti, Mohammad H; Tang, Haixiong; Sodano, Henry A

    2016-03-07

    Lead-free piezoelectric nanowires (NWs) show strong potential in sensing and energy harvesting applications due to their flexibility and ability to convert mechanical energy to electric energy. Currently, most lead-free piezoelectric NWs are produced through low yield synthesis methods and result in low electromechanical coupling, which limit their efficiency as energy harvesters. In order to alleviate these issues, a scalable method is developed to synthesize perovskite type 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) NWs with high piezoelectric coupling coefficient. The piezoelectric coupling coefficient of the BZT-BCT NWs is measured by a refined piezoresponse force microscopy (PFM) testing method and shows the highest reported coupling coefficient for lead-free piezoelectric nanowires of 90 ± 5 pm V(-1). Flexible nanocomposites utilizing dispersed BZT-BCT NWs are fabricated to demonstrate an energy harvesting application with an open circuit voltage of up to 6.25 V and a power density of up to 2.25 μW cm(-3). The high electromechanical coupling coefficient and high power density demonstrated with these lead-free NWs produced via a scalable synthesis method shows the potential for high performance NW-based devices.

  15. Structural and electrical properties of 1 − x(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–x(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} ceramics

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

    Lee, Tae-Ho; Lee, Sung-Gap, E-mail: lsgap@gnu.ac.kr; Yeo, Jin-Ho

    2014-10-15

    Highlights: • We fabricated lead-free (Na{sub 0.5}K{sub 0.5})NbO{sub 3} ceramics. • We studied the structural and electrical properties of 1 − x(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–x(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} ceramics. • The structural and electrical properties improved with increasing amount of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3}. - Abstract: In this study, 1 − x(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–x(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} ceramics were fabricated using the conventional mixed oxide method. The effects of the addition of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} on the structural and electrical properties of the specimens were investigated for their application in piezoelectric devices. As the results of X-ray diffractionmore » analysis show, all specimens display the typical polycrystalline perovskite structure without the presence of the second phase. Sintered densities increased with an increase in the amount of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} added and the specimen with 0.08 mol% of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} added showed the maximum value of 4.54 g/cm{sup 3}. Both average grain size and densification increased with an increase in the amount of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3}. The electromechanical coupling factor, dielectric constant ϵ{sub r}, dielectric loss tan δ, d{sub 33} and Curie temperature of the 0.92(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–0.08(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} specimens doped with 0.08 mol% of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} were 0.31, 1338, 0.021, 138 and 445 °C, respectively.« less

  16. Redox and complexation chemistry of the CrVI/CrV-D-glucaric acid system.

    PubMed

    Mangiameli, María Florencia; González, Juan Carlos; Bellú, Sebastián; Bertoni, Fernando; Sala, Luis F

    2014-06-28

    When an excess of uronic acid over Cr(VI) is used, the oxidation of D-glucaric acid (Glucar) by Cr(VI) yields D-arabinaric acid, CO2 and Cr(III)-Glucar complex as final redox products. The redox reaction involves the formation of intermediate Cr(IV) and Cr(V) species. The reaction rate increases with [H(+)] and [substrate]. The experimental results indicated that Cr(IV) and Cr(V) are very reactive intermediates since their disappearance rates are much faster than Cr(VI). Cr(IV) and Cr(V) intermediates are involved in fast steps and do not accumulate in the redox reaction of the mixture Cr(VI)-Glucar. Kinetic studies show that the redox reaction between Glucar and Cr(VI) proceeds through a mechanism combining one- and two-electron pathways: Cr(VI) → Cr(IV) → Cr(II) and Cr(VI) → Cr(IV) → Cr(III). After the redox reaction, results show a slow hydrolysis of the Cr(III)-Glucar complex into [Cr(OH2)6](3+). The proposed mechanism is supported by the observation of free radicals, CrO2(2+) (superoxo-Cr(III) ion) and oxo-Cr(V)-Glucar species as reaction intermediates. The continuous-wave electron paramagnetic resonance, CW-EPR, spectra show that five-coordinate oxo-Cr(V) bischelates are formed at pH ≤ 4 with the aldaric acid bound to oxo-Cr(V) through the carboxylate and the α-OH group. A different oxo-Cr(V) species with Glucar was detected at pH 6.0. The high g(iso) value for the last species suggests a mixed coordination species, a five-coordinated oxo-Cr(V) bischelate with one molecule of Glucar acting as a bi-dentate ligand, using the 2-hydroxycarboxylate group, and a second molecule of Glucar with any vic-diolate sites. At pH 7.5 only a very weak EPR signal was observed, which may point to instability of these complexes. This behaviour contrasts with oxo-Cr(V)-uronic species, and must thus be related to the Glucar acyclic structure. In vitro, our studies on the chemistry of oxo-Cr(V)-Glucar complexes can provide information on the nature of the species that

  17. Microstructure/Oxidation/Microhardness Correlations in Gamma-Based and Tau-Based Al-Ti-Cr Alloys

    NASA Technical Reports Server (NTRS)

    Brady, Michael P.; Smialek, J. L.; Humphrey, D. L.

    1994-01-01

    The relationships between alloy microstructure and air oxidation kinetics and alloy microstructure and microhardness in the Al-Ti-Cr system for exposures at 800 C and 1000 C were investigated. The relevant phases were identified as tau (Ll2), gamma (LIO), r-Al2Ti, TiCrAl (laves), and Cr2AI. Protective alumina formation was associated with tau, Al-rich TiCrAl, and gamma/TiCrAl mixtures. Brittleness was associated with the TiCrAl phase and tau decomposition to A12Ti + Cr2AI. It was concluded that two-phase gamma + TiCrAl alloys offer the greatest potential for oxidation resistance and room temperature ductility in the Al-Ti-Cr system.

  18. 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.

  19. Magnetic effect on oxide-scale growth of Fe-5Cr alloy

    NASA Astrophysics Data System (ADS)

    Zhou, C. H.; Li, X. W.; Wang, S. H.; Ma, H. T.

    2018-01-01

    The oxidation behaviour of Fe-5Cr alloy was investigated at 650°C in the presence of magnetic field. Results indicated that the oxide scales were both consisted of an outer Fe-oxide scale and an inner mixed-oxide scale in the presence or absence of magnetic field. The oxide-scale growth of Fe-5Cr alloy, gained by measuring the oxide-scale thickness, was verified to follow parabolic lawyer. And the oxidation kinetics showed that the applied magnetic field retarded the oxide-scale growth of Fe-5Cr alloy.

  20. Electronic and optical properties of Cr-, B-doped, and (Cr, B)-codoped SrTiO3

    NASA Astrophysics Data System (ADS)

    Wu, Jiao; Huang, Wei-Qing; Yang, Ke; Wei, Zeng-Xi; Peng, P.; Huang, Gui-Fang

    2017-04-01

    Energy band engineering of semiconductors plays a crucial role in exploring high-efficiency visible-light response photocatalysts. Herein, we systematically study the electronic properties and optical response of Cr-, B-doped SrTiO3, and (Cr, B)-codoped SrTiO3 by using first-principles calculations to explore the mechanism for its superior photocatalytic activities in the visible light region. Special emphasis is placed on uncovering the synergy effects of nonmetal B dopant with metal Cr dopant at different cation sites. It is found that the electronic properties and optical absorption of SrTiO3 can be dramatically engineered by mono- or co-doping. In particular, the intermediate levels lying in the bandgap of the codoped SrTiO3 relay on the Cr impurity doped at Sr or Ti cation sites. Moreover, the (Cr@Sr, B@O)-SrTiO3 retains the charge balancing without the generation of unexpected oxygen vacancies, and is more desirable for solar light harvesting due to its higher absorption than others in the entire visible light. The findings can rationalize the available experimental results and are helpful in designing SrTiO3-based photocatalysts with high-efficiency performance.

  1. Studies on corrosion resistance and bio-activity of plasma spray deposited hydroxylapatite (HA) based TiO2 and ZrO2 dispersed composite coatings on titanium alloy (Ti-6Al-4V) and the same after post spray heat treatment

    NASA Astrophysics Data System (ADS)

    Kumari, Renu; Majumdar, Jyotsna Dutta

    2017-10-01

    In the present study, the effect of plasma spray deposited hydroxylapatite (HA) based TiO2 dispersed (HA + 50 wt.% TiO2), coating and post spray heat treatment to be referred as HA-TiO2 (heat treated at 650 °C for 2 h) and ZrO2 dispersed (HA + 10 wt.% ZrO2), to be referred as HA-ZrO2 coating (heat treated at 750 °C for 2 h) on corrosion resistance and bioactivity of Ti-6Al-4V substrate has been undertaken. There is partial decomposition of HA to tri-calcium-phosphate (Ca3(PO4)2) and formation of CaTiO3 phase in HA-TiO2 coating and CaZrO3 phase in the HA-ZrO2 coating. Corrosion study in Hank's solution shows that there is shifting of corrosion potential (Ecorr) towards active potential (-1.1 V(SCE) for as-sprayed and post spray heat treated HA-TiO2 coating, -1.1 V(SCE) for as-sprayed HA-ZrO2 coating and -1 V(SCE) for HA-ZO2 coating after post spray heat treatment), and deterioration in pitting corrosion (Epit) resistance in as-sprayed coatings and the same after heat treatment (-0.7 V(SCE) for both HA-TiO2 and HA-ZrO2 coating as compared to as received substrate (-0.3 V(SCE)). The corrosion rate was increased for both the coatings with a maximum increase in HA-ZrO2 coating. Bioactivity test shows a higher degree of apatite deposition in as-sprayed coating and the same after heat treatment as compared to as received Ti-6Al-4V though the as-sprayed one showed a superior behavior.

  2. Microstructural, optical and electrical properties of LaFe0.5Cr0.5O3 perovskite nanostructures

    NASA Astrophysics Data System (ADS)

    Ali, S. Asad; Naseem, Swaleha; Khan, Wasi; Sharma, A.; Naqvi, A. H.

    2016-05-01

    Perovskite nanocrystalline powder of LaFe0.5Cr0.5O3 was synthesized by sol-gel combustion route and characterized by x-ray diffractometer (XRD), scanning electron microscopy (SEM) equipped with EDS, UV-visible and LCR meter at room temperature Rietveld refinement of the XRD data confirms that the sample is in single phase-rhombohedral structure with space group R-3C. SEM micrograph shows clear nanostructure of the sample and EDS ensures the presence of all elements in good stoichiometric. The optical absorption indicates the maximum absorption at 315 nm and optical band gap of 2.94 eV was estimated using Tauc's relation. Dielectric constant (ɛ') and loss were found to decrease with increase in frequencies. The dielectric behavior was explained on the basis of Maxwell-Wagner's two layer model.

  3. TOUGH+ v1.5 Core Code

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

    Moridis, George J.

    TOUGH+ v1.5 is a numerical code for the simulation of multi-phase, multi-component flow and transport of mass and heat through porous and fractured media, and represents the third update of the code since its first release [Moridis et al., 2008]. TOUGH+ is a successor to the TOUGH2 [Pruess et al., 1991; 2012] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95/2003, and can be run on any computational platform (workstations, PC, Macintosh). TOUGH+ v1.5 employs dynamic memory allocation, thus minimizing storage requirements. It has amore » completely modular structure, follows the tenets of Object-Oriented Programming (OOP), and involves the advanced features of FORTRAN 95/2003, i.e., modules, derived data types, the use of pointers, lists and trees, data encapsulation, defined operators and assignments, operator extension and overloading, use of generic procedures, and maximum use of the powerful intrinsic vector and matrix processing operations. TOUGH+ v1.5 is the core code for its family of applications, i.e., the part of the code that is common to all its applications. It provides a description of the underlying physics and thermodynamics of non-isothermal flow, of the mathematical and numerical approaches, as well as a detailed explanation of the general (common to all applications) input requirements, options, capabilities and output specifications. The core code cannot run by itself: it needs to be coupled with the code for the specific TOUGH+ application option that describes a particular type of problem. The additional input requirements specific to a particular TOUGH+ application options and related illustrative examples can be found in the corresponding User's Manual.« less

  4. Fabrication of thin film TiO2 nanotube arrays on Co-28Cr-6Mo alloy by anodization.

    PubMed

    Ni, Jiahua; Frandsen, Christine J; Noh, Kunbae; Johnston, Gary W; He, Guo; Tang, Tingting; Jin, Sungho

    2013-04-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

    NASA Astrophysics Data System (ADS)

    Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

    2017-12-01

    Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

  6. Investigation of the fracture mechanism in Ti-5Al-2.5Sn at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Vanstone, R. H.; Low, J. R., Jr.; Shannon, J. L., Jr.

    1977-01-01

    The influence of microstructure on the fracture mechanism and plane-strain fracture toughness of Ti-5Al-2.5Sn was studied through the use of fractography and metallographic sectioning techniques. One-inch thick plates of extra low interstitial (ELI) and normal interstitial Ti-5Al-2.5Sn were mill annealed at 815 C followed by either air or furnace cooling. These variations in composition and cooling rate resulted in differences in the volume fraction and internal structure of the iron-stabilized phase, and in the crystallographic texture and ordering of the alpha matrix. The tensile properties of these plates were determined at 20 K, 77 K, and 295 K. The air-cooled ELI plate was the toughest material evaluated.

  7. Study on the decomposition of trace benzene over V2O5–WO3/TiO2-based catalysts in simulated flue gas

    EPA Science Inventory

    Trace levels (1 and 10 ppm) of gaseous benzene were catalytically decomposed in a fixed-bed catalytic reactor with monolithic oxides of vanadium and tungsten supported on titanium oxide (V2O5–WO3/TiO2) catalysts under conditions simulating the cooling of waste incineration flue g...

  8. (Ba+Sr)/Ti ratio dependence of the dielectric properties for (Ba0.5Sr0.5)TiO3 thin films prepared by ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Yamamichi, Shintaro; Yabuta, Hisato; Sakuma, Toshiyuki; Miyasaka, Yoichi

    1994-03-01

    (Ba0.5Sr0.5)TiO3 thin films were prepared by ion beam sputtering from powder targets with (Ba+Sr)/Ti ratios ranging from 0.80 to 1.50. All of the perovskite (Ba,Sr)TiO3 films were single phase except for the film with a (Ba+Sr)/Ti ratio of 1.41. The dielectric constant values notably depended on the (Ba+Sr)/Ti ratio for films thicker than 70 nm. The highest dielectric constant of 580 was achieved for the 5% (Ba+Sr) rich film. This (Ba+Sr)/Ti ratio dependence was diminished by the thickness dependence for thinner films. The grain sizes for the 9% (Ba+Sr) rich film and for the 6% (Ba+Sr) poor film ranged from 70 to 100 nm and from 30 to 60 nm, respectively. This grain size difference could explain why slightly A-site rich (Ba,Sr)TiO3 films have a larger dielectric constant than A-site poor films.

  9. Low-cost, high-strength Fe--Ni--Cr alloys for high temperature exhaust valve application

    DOEpatents

    Muralidharan, Govindarajan

    2017-09-05

    An Fe--Ni--Cr alloy is composed essentially of, in terms of wt. %: 2.4 to 3.7 Al, up to 1.05 Co, 14.8 to 15.9 Cr, 25 to 36 Fe, up to 1.2 Hf, up to 4 Mn, up to 0.6 Mo, up to 2.2 Nb, up to 1.05 Ta, 1.9 to 3.6 Ti, up to 0.08 W, up to 0.03 Zr, 0.18 to 0.27 C, up to 0.0015 N, balance Ni, wherein, in terms of atomic percent: 8.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.11.5, 0.53.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.65, and 0.16.ltoreq.Cr/(Fe+Ni+Cr+Mn).ltoreq.0.21, the alloy being essentially free of Cu, Si, and V.

  10. Electrical Characteristics and Preparation of Nanostructured Pb(Zr0.5Ti0.5)O3 Films by Spray Pyrolysis

    NASA Astrophysics Data System (ADS)

    Koo, Horng-Show; Chen, Mi; Hotta, Yoichi; Kawai, Tomoji

    2007-07-01

    Nanostructured thin films of Pb(Zr0.5Ti0.5)O3 on Pt (1000 Å)/Ti (100 Å)/SiO2 (2000 Å)/Si substrates are prepared by spray pyrolysis and subsequently rapid thermal annealing. Lead nitrate, zirconium nitrate and titanium isopropoxide are used as starting material with ethylene glycol as solvent. The crystal structure of the as-sprayed films are transformed from the amorphous, pyrochlore and multiple phases of pyrochlore and perovskite to the single phase of perovskite as the annealing temperature is increased up to 500 °C. For the formation of single phase perovskite, excess lead of 10 mol % is required to compensate the loss of lead during the processing of the primitive films. The physical characteristics of the resultant films show the dielectric constant (\\varepsilonr) of 400, remanent polarization (2Pr) of 30.0 μC/cm2 and coercive field (2Ec) of 70.0 kV/cm, respectively.

  11. Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3

    NASA Astrophysics Data System (ADS)

    Birks, E.; Dunce, M.; Peräntie, J.; Hagberg, J.; Sternberg, A.

    2017-06-01

    Direct and indirect studies of the electrocaloric effect were carried out in poled and depoled Na0.5Bi0.5TiO3. For this purpose, polarization and electrocaloric effect temperature change measurements were made at different electric field pulses as a function of temperature. The applicability of the widely used indirect electrocaloric effect determination method, using the Maxwell relation, was critically analyzed with respect to the reliable direct measurements. Quantitative differences were observed between the results obtained by both approaches in the case of the poled Na0.5Bi0.5TiO3 sample. These differences can be explained by the temperature-dependent concentration of domains oriented in the direction of the applied electric field. Whereas in depoled Na0.5Bi0.5TiO3, which is characterized by the electric field dependence of polar nanoregions embedded in a nonpolar matrix, the Maxwell relation is not applicable at all, as it is indicated by the obtained results. Possible mechanisms which could be responsible for the electrocaloric effect in the relaxor state were considered. The results of this study are used to evaluate the numerous results obtained and published by other authors, using the Maxwell relation to indirectly determine the electrocaloric effect. The reason for the negative values of the electrocaloric effect, obtained in such a way and widely discussed in the literature in the case of Na0.5Bi0.5TiO3, has been explained in this study.

  12. Sm5(Fe,Ti)17 melt-spun ribbons with high coercivity

    NASA Astrophysics Data System (ADS)

    Saito, Tetsuji; Horita, Toru

    2018-05-01

    It has previously been reported that annealing of amorphous Sm5Fe17 melt-spun ribbon resulted in the formation of the Sm5Fe17 phase and the resultant Sm5Fe17 melt-spun ribbon exhibited a high coercivity. However, the annealing condition of the amorphous Sm5Fe17 melt-spun ribbon was somewhat critical and it was not easy to obtain Sm5Fe17 grains with high coercivity. In the present study, it was found that the small substitution of Ti for Fe in the Sm5Fe17 melt-spun ribbon stabilized the Sm5Fe17 phase. Annealed Sm5Fe16.7Ti0.3 melt-spun ribbon consisted of small and homogeneous Sm5(Fe,Ti)17 grains and exhibited a higher coercivity than the annealed Sm5Fe17 melt-spun ribbon.

  13. Preparation and characterization of α-Al2O3 film by low temperature thermal oxidation of Al8Cr5 coating

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Xu, Bajin; Ling, Guoping

    2015-03-01

    In this paper, α-Al2O3 film was prepared by low temperature thermal oxidation of Al8Cr5 coating. The Al8Cr5 alloy coating was prepared on SUS430 stainless steel through a two-step approach including electrodepositing Cr/Al composite coating and subsequent heat treatment at 740 °C for 16 h. After mechanical polishing removal of voids on the surface, the Al8Cr5 coating was thermal oxidized at 720 °C in argon for 100 h. The samples were characterized by SEM, EDX, XRD, XPS and TEM. XPS detection on the surface of oxidized Al8Cr5 coating showed that the oxide film mainly consisted of Al2O3. TEM characterization of the oxide film showed that it was α-Al2O3 films ca. 110 nm. The formation of α-Al2O3 films at low temperature can be attributed to the formation of Cr2O3 nuclei at the initial stage of oxidation which lowers the nucleation energy barrier of α-Al2O3.

  14. Genetic susceptibility to interstitial pulmonary fibrosis in mice induced by vanadium pentoxide (V2O5)

    PubMed Central

    Walters, Dianne M.; White, Kevin M.; Patel, Ushma; Davis, Martin J.; Veluci-Marlow, Roberta M.; Bhupanapadu Sunkesula, Solomon Raju; Bonner, James C.; Martin, Jessica R.; Gladwell, Wes; Kleeberger, Steven R.

    2014-01-01

    Interstitial lung diseases (ILDs) are characterized by injury, inflammation, and scarring of alveoli, leading to impaired function. The etiology of idiopathic forms of ILD is not understood, making them particularly difficult to study due to the lack of appropriate animal models. Consequently, few effective therapies have emerged. We developed an inbred mouse model of ILD using vanadium pentoxide (V2O5), the most common form of a transition metal found in cigarette smoke, fuel ash, mineral ores, and steel alloys. Pulmonary responses to V2O5, including dose-dependent increases in lung permeability, inflammation, collagen content, and dysfunction, were significantly greater in DBA/2J mice compared to C57BL/6J mice. Inflammatory and fibrotic responses persisted for 4 mo in DBA/2J mice, while limited responses in C57BL/6J mice resolved. We investigated the genetic basis for differential responses through genetic mapping of V2O5-induced lung collagen content in BXD recombinant inbred (RI) strains and identified significant linkage on chromosome 4 with candidate genes that associate with V2O5-induced collagen content across the RI strains. Results suggest that V2O5 may induce pulmonary fibrosis through mechanisms distinct from those in other models of pulmonary fibrosis. These findings should further advance our understanding of mechanisms involved in ILD and thereby aid in identification of new therapeutic targets.—Walters, D. M., White, K. M., Patel, U., Davis, M. J., Veluci-Marlow, R. M., Bhupanapadu Sunkesula, S. R., Bonner, J. C., Martin, J. R., Gladwell, W., Kleeberger, S. R. Genetic susceptibility to interstitial pulmonary fibrosis in mice induced by vanadium pentoxide (V2O5). PMID:24285090

  15. [Cr-Ti-Al-N complex coating on titanium to strengthen Ti/porcelain bonding].

    PubMed

    Zhang, Hui; Guo, Tian-wen; Li, Jun-ming; Pan, Jing-guang; Dang, Yong-gang; Tong, Yu

    2006-02-01

    To study the feasibility of magnetron sputtering Cr-Ti-Al-N complex coating as an interlayer on titanium to enhance the titanium-ceramic binding strength. With a three-point bending test according to ISO 9693, the binding strength of Duceratin (Degussa) to titanium substrate prepared with 4 different surface treatments (polishing, polishing and megnetron sputtering Cr, Ti, Al, and N complex coating, sandblasting, sandblasting and coating) was evaluated. Ti/porcelain interface and fractured Ti surface were examined using scanning electron microscopy with energy-dispersive spectrometry (EDS). The binding strength of polished and coated titanium/Duceratin was significantly higher than polished titanium group (P<0.05). The binding strength of sandblasted and coated titanium/Duceratin did not differ significantly from that of sandblasted titanium group (P>0.05), and the strength in the two sandblasted titanium groups was significantly higher than that in polished and coated titanium group (P<0.05). Megnetron sputtering Cr-Ti-Al-N complex on polished titanium can increase the titanium/porcelain binding strength. Megnetron sputtering coating is a promising Ti/porcelain interlayer.

  16. Characterization and diffusion model for the titanium boride layers formed on the Ti6Al4V alloy by plasma paste boriding

    NASA Astrophysics Data System (ADS)

    Keddam, Mourad; Taktak, Sukru

    2017-03-01

    The present study is focused on the estimation of activation energy of boron in the plasma paste borided Ti6Al4V alloy, which is extensively used in technological applications, using an analytical diffusion model. Titanium boride layers were successfully produced by plasma paste boriding method on the Ti6Al4V alloy in the temperature range of 973-1073 K for a treatment time ranging from 3 to 7 h. The presence of both TiB2 top-layer and TiB whiskers sub-layer was confirmed by the XRD analysis and SEM observations. The surface hardness of the borided alloy was evaluated using Micro-Knoop indenter. The formation rates of the TiB2 and TiB layers were found to have a parabolic character at all applied process temperatures. A diffusion model was suggested to estimate the boron diffusivities in TiB2 and TiB layers under certain assumptions, by considering the effect of boride incubation times. Basing on own experimental data on boriding kinetics, the activation energies of boron in TiB2 and TiB phases were estimated as 136.24 ± 0.5 and 63.76 ± 0.5 kJ mol-1, respectively. Finally, the obtained values of boron activation energies for Ti6Al4V alloy were compared with the data available in the literature.

  17. Cooling field and temperature dependent exchange bias in Gd substituted YFe0.5Cr0.5O3

    NASA Astrophysics Data System (ADS)

    Singh, Karan; Mukherjee, K.

    2018-04-01

    We report the results of our investigation of cooling field and temperature dependence of exchange bias on Gd substituted mixed metal oxide YFe0.5Cr0.5O3. A negative exchange bias is observed in the Gd-substituted compounds, in contrast to the positive exchange bias in parent compound, YFe0.5Cr0.5O3 [1]. With the increase in Gd concentration it is noted that the exchange bias decreases. It was noted that the paramagnetic contribution from Gd ions plays the leading role in comparison to the antiferromagnetic type correlations among spins as is observed for the parent compound. Due to magnetic rare earth ion, additional exchange interaction of the form Gd-O-Fe/Cr dominates the magnetic interaction arising due to the transition metal ions, resulting in the reduction in exchange bias value.

  18. Microstructure-strength relations in a hardenable stainless steel with 16 pct Cr, 1.5 pct Mo, and 5 pct Ni

    NASA Astrophysics Data System (ADS)

    Grobner, P. J.; Blšs, V.

    1984-07-01

    Metallographic studies have been conducted on a 0.024 pct C-16 pct Cr-1.5 pct Mo-5 pct Ni stainless steel to study the phase reactions associated with heat treatments and investigate the strengthening mechanisms of the steel. In the normalized condition, air cooled from 1010 °C, the microstructure consists of 20 pct ferrite and 80 pct martensite. Tempering in a temperature range between 500 and 600 °C results in a gradual transformation of martensite to a fine mixture of ferrite and austenite. At higher tempering temperatures, between 600 and 800 °C, progressively larger quantities of austenite form and are converted during cooling to proportionally increasing amounts of fresh martensite. The amount of retained austenite in the microstructure is reduced to zero at 800 °C, and the microstructure contains 65 pct re-formed martensite and 35 pct total ferrite. Chromium rich M23C6 carbides precipitate in the single tempered microstructures. The principal strengthening is produced by the presence of martensite in the microstructure. Additional strengthening is provided by a second tempering treatment at 400 °C due to the precipitation of ultrafine (Cr, Mo) (C,N) particles in the ferrite.

  19. Probing surface sites of TiO2: reactions with [HRe(CO)5] and [CH3Re(CO)5].

    PubMed

    Lobo-Lapidus, Rodrigo J; Gates, Bruce C

    2010-10-04

    Two carbonyl complexes of rhenium, [HRe(CO)(5)] and [CH(3)Re(CO)(5)], were used to probe surface sites of TiO(2) (anatase). These complexes were adsorbed from the gas phase onto anatase powder that had been treated in flowing O(2) or under vacuum to vary the density of surface OH sites. Infrared (IR) spectra demonstrate the variation in the number of sites, including Ti(+3)-OH and Ti(+4)-OH. IR and extended X-ray absorption fine structure (EXAFS) spectra show that chemisorption of the rhenium complexes led to their decarbonylation, with formation of surface-bound rhenium tricarbonyls, when [HRe(CO)(5)] was adsorbed, or rhenium tetracarbonyls, when [CH(3)Re(CO)(5)] was adsorbed. These reactions were accompanied by the formation of water and surface carbonates and removal of terminal hydroxyl groups associated with Ti(+3) and Ti(+4) ions on the anatase. Data characterizing the samples after adsorption of [HRe(CO)(5)] or [CH(3)Re(CO)(5)] determined a ranking of the reactivity of the surface OH sites, with the Ti(+3)-OH groups being the more reactive towards the rhenium complexes but the less likely to be dehydroxylated. The two rhenium pentacarbonyl probes provided complementary information, suggesting that the carbonate species originate from carbonyl ligands initially bonded to the rhenium and from hydroxyl groups of the titania surface, with the reaction leading to the formation of water and bridging hydroxyl groups on the titania. The results illustrate the value of using a family of organometallic complexes as probes of oxide surface sites.

  20. 75 FR 6860 - Airworthiness Directives; International Aero Engines AG (IAE) V2500-A1, V2522-A5, V2524-A5, V2525...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-12

    ... Airworthiness Directives; International Aero Engines AG (IAE) V2500-A1, V2522-A5, V2524-A5, V2525-D5, V2527-A5, V2527E-A5, V2527M-A5, V2528-D5, V2530-A5, and V2533-A5 Turbofan Engines AGENCY: Federal Aviation... airworthiness directive (AD) for all International Aero Engines AG (IAE) V2500-A1, V2525-D5 and V2528-D5...

  1. Comparison of the effects of Mg-6Zn and Ti-3Al-2.5V alloys on TGF-β/TNF-α/VEGF/b-FGF in the healing of the intestinal tract in vivo.

    PubMed

    Yan, Jun; Chen, Yigang; Yuan, Qingling; Wang, Xiaohu; Yu, Song; Qiu, Wencai; Wang, Zhigang; Ai, Kaixing; Zhang, Xiaonong; Zhang, Shaoxiang; Zhao, Changli; Zheng, Qi

    2014-04-01

    To evaluate the different effects of Mg-6Zn alloy and Ti-3Al-2.5V alloy implants in intestinal tract healing, we compared these two different alloys with respect to their effect on a rat's intestinal tract, using serum magnesium, radiology, pathology and immunohistochemistry in vivo. It was found using the scanning electron microscope that the Mg-6Zn alloy began to degrade during the first week and that the Ti-3Al-2.5V alloy was non-degradable throughout the process. The Mg-6Zn alloy did not have an impact on serum magnesium. Superior to the Ti-3Al-2.5V alloy, the Mg-6Zn alloy enhanced the expression of transforming growth factor-β1 in healing tissue, and promoted the expression of both the vascular endothelial growth factor and the basic fibroblast growth factor, which helped angiogenesis and healing. The Mg-6Zn alloy reduced the expression of the tumor necrosis factor (TNF-α) at different stages and decreased inflammatory response, which may have been related to the zinc inhibiting TNF-α. In general, the Mg-6Zn alloy performed better than Ti-3Al-2.5V at promoting healing and reducing inflammation. The Mg-6Zn alloy may be a promising candidate for use in the pins of circular staplers for gastrointestinal reconstruction in medicine.

  2. The NuSTAR view on Hard-TeV BL Lacs

    NASA Astrophysics Data System (ADS)

    Costamante, L.; Bonnoli, G.; Tavecchio, F.; Ghisellini, G.; Tagliaferri, G.; Khangulyan, D.

    2018-05-01

    Hard-TeV BL Lacs are a new type of blazars characterized by a hard intrinsic TeV spectrum, locating the peak of their gamma-ray emission in the spectral energy distribution (SED) above 2-10 TeV. Such high energies are problematic for the Compton emission, using a standard one-zone leptonic model. We study six examples of this new type of BL Lacs in the hard X-ray band with NuSTAR. Together with simultaneous observations with the Neil Gehrels Swift Observatory, we fully constrain the peak of the synchrotron emission in their SED, and test the leptonic synchrotron self-Compton (SSC) model. We confirm the extreme nature of 5 objects also in the synchrotron emission. We do not find evidence of additional emission components in the hard X-ray band. We find that a one-zone SSC model can in principle reproduce the extreme properties of both peaks in the SED, from X-ray up to TeV energies, but at the cost of i) extreme electron energies with very low radiative efficiency, ii) conditions heavily out of equipartition (by 3 to 5 orders of magnitude), and iii) not accounting for the simultaneous UV data, which then should belong to a different emission component, possibly the same as the far-IR (WISE) data. We find evidence of this separation of the UV and X-ray emission in at least two objects. In any case, the TeV electrons must not "see" the UV or lower-energy photons, even if coming from different zones/populations, or the increased radiative cooling would steepen the VHE spectrum.

  3. Laser Powder Welding of a Ti52Al46.8Cr1Si0.2Titanium Aluminide Alloy at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Smal, C. A.; Meacock, C. G.; Rossouw, H. J.

    2011-04-01

    A method for the joining of a Ti52Al46.8Cr1Si0.2Titanium Aluminide alloy by laser powder welding is presented. The technique acts to join materials by consolidating powder with focused laser beam to form weld beads that fill a V joint. In order to avoid the occurrence of residual thermal stresses and hence cracking of the brittle material, the weld plates were heated to a temperature of 1173 K (= 900 °C) by an ohmic heating device, welded and then slowly cooled to produce pore and crack free welds.

  4. Electronic structures and abnormal phonon behaviors of cobalt-modified Na0.5Bi0.5TiO3-6%BaTiO3 single crystals

    NASA Astrophysics Data System (ADS)

    Huang, T.; Zhang, P.; Xu, L. P.; Chen, C.; Zhang, J. Z.; Hu, Z. G.; Luo, H. S.; Chu, J. H.

    2016-10-01

    Optical properties, electronic structures, and structural variations of x wt% cobalt (Co) doped Na0.5Bi0.5TiO3-6%BaTiO3 (x=0%, 0.5%, 0.8%) single crystals have been studied by temperature-dependent optical ellipsometry and Raman spectra from 250 to 650 K. Based on the temperature evolution of electronic transitions (Ecp1 and Ecp2) and the phonon modes involving Ti-O vibrations, two critical temperature points exhibit an increasing trend with Co dopants, which are related to structural variations for ferroelectric to anti-ferroelectric, and anti-ferroelectric to paraelectric transition, respectively. Additionally, distinguishing abnormal phonon behaviors can be observed from Raman spectra for the crystal of x=0.5% and 0.8%, which show reverse frequency shift of the modes involving Ti-O vibration. It can be ascribed to different relative concentration of Co2+ and Co3+ in the crystals, which has been confirmed by X-ray Photoelectron Spectroscopy data.

  5. Molecular dynamics studies of displacement cascades in Fe-Y{sub 2}TiO{sub 5} system

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

    Dholakia, Manan, E-mail: manan@igcar.gov.in; Chandra, Sharat; Jaya, S. Mathi

    The effect of displacement cascade on Fe-Y{sub 2}TiO{sub 5} bilayer is studied using classical molecular dynamics simulations. Different PKA species – Fe, Y, Ti and O – with the same PKA energy of 8 keV are used to produce displacement cascades that encompass the interface. It is shown that Ti atom has the highest movement in the ballistic regime of cascades which can lead to Ti atoms moving out of the oxide clusters into the Fe matrix in ODS alloys.

  6. Fretting Wear of Ti-48Al-2Cr-2Nb

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Lerch, Bradley A.; Draper, Susan L.

    2001-01-01

    An investigation was conducted to examine the wear behavior of gamma titanium aluminide (Ti-48Al-2Cr-2Nb in atomic percent) in contact with a typical nickel-base superalloy under repeated microscopic vibratory motion in air at temperatures from 296-823 K. The surface damage observed on the interacting surfaces of both Ti-48Al-2Cr-2Nb and superalloy consisted of fracture pits, oxides, metallic debris, scratches, craters, plastic deformation, and cracks. The Ti-48Al-2Cr-2Nb transferred to the superalloy at all fretting conditions and caused scuffing or galling. The increasing rate of oxidation at elevated temperatures led to a drop in Ti-48Al-2Cr-2Nb wear at 473 K. Mild oxidative wear was observed at 473 K. However, fretting wear increased as the temperature was increased from 473-823 K. At 723 and 823 K, oxide disruption generated cracks, loose wear debris, and pits on the Ti-48Al-2Cr-2Nb wear surface. Ti-48Al-2Cr-2Nb wear generally decreased with increasing fretting frequency. Both increasing slip amplitude and increasing load tended to produce more metallic wear debris, causing severe abrasive wear in the contacting metals. Keywords

  7. Development of the 5-HT2CR-Tango System Combined with an EGFP Reporter Gene.

    PubMed

    Watanabe, Yoshihisa; Tsujimura, Atsushi; Aoki, Miku; Taguchi, Katsutoshi; Tanaka, Masaki

    2016-02-01

    The serotonin 2C receptor (5-HT2CR) is a G-protein-coupled receptor implicated in emotion, feeding, reward, and cognition. 5-HT2CRs are pharmacological targets for mental disorders and metabolic and reward system abnormalities, as alterations in 5-HT2CR expression, RNA editing, and SNPs are involved in these disturbances. To date, 5-HT2CR activity has mainly been measured by quantifying inositol phosphate production and intracellular Ca(2+) release, but these assays are not suitable for in vivo analysis. Here, we developed a 5-HT2CR-Tango assay system, a novel analysis tool of 5-HT2CR activity based on the G-protein-coupled receptor (GPCR)-arrestin interaction. With desensitization of activated 5-HT2CR by arrestin, this system converts the 5-HT2CR-arrestin interaction into EGFP reporter gene signal via the LexA transcriptional activation system. For validation of our system, we measured activity of two 5-HT2CR RNA-editing isoforms (INI and VGV) in HEK293 cells transfected with EGFP reporter gene. The INI isoform displayed both higher basal- and 5-HT-stimulated activities than the VGV isoform. Moreover, an inhibitory effect of 5-HT2CR antagonist SB242084 was also detected by 5-HT2CR-Tango system. This novel tool is useful for in vitro high-throughput targeted 5-HT2CR drug screening and can be applied to future in vivo brain function studies associated with 5-HT2CRs in transgenic animal models.

  8. Anisotropic electrical and lattice transport properties of ordered quaternary phases Cr2TiAlC2 and Mo2TiAlC2: A first principles study

    NASA Astrophysics Data System (ADS)

    Li, Y. F.; Ding, Y. C.; Xiao, B.; Cheng, Y. H.

    2016-11-01

    Electrical conductivities of Cr2TiAlC2 and Mo2TiAlC2 in a and c directions are calculated from semi-classic Boltzmann transport theory. The values are found to be σa = 5.68 ×105 S /m (6.56 ×105 S /m) and σc = 2.15 ×105 S /m (2.69 ×105 S /m) for Cr2TiAlC2 (Mo2TiAlC2) at 300 K. Using the phonon-mode Debye temperature and Slack-model, the lattice thermal conductivities in the two directions are also evaluated, and the values are κa = 18.71 W /m K (16.11 W/m K) and κc = 0.48 W /m K (0.25 W /m K) for Cr2TiAlC2 (Mo2TiAlC2) at room temperature. The anisotropy in lattice thermal conductivity is found to be stronger than that of electrical conductivity. The predicted Seebeck coefficients and thermoelectric figure of merit (ZT) indicate that they are poor thermoelectric materials. Due to the relatively high conductivities, they might be used to fabricate high temperature conductive components in aerospace industry. In addition, our results in a direction have the direct implications for the relevant properties of MXenes (Cr2TiC2 and Mo2TiC2), produced from their bulk phases.

  9. Solution treatment-delayed zirconium-strengthening behavior in Ti-7.5Mo-xZr alloy system

    NASA Astrophysics Data System (ADS)

    Chern Lin, Jiin-Huey; Fu, Yen-Han; Chen, Yen-Chun; Peng, Yu-Po; Ju, Chien-Ping

    2018-01-01

    The present study was devoted to investigate and compare the Zr-strengthening behavior in as-cast (AC) and solution-treated (ST) Ti-7.5Mo-xZr alloys. The experimental results indicated that AC Ti-7.5Mo and AC Ti-7.5Mo-1Zr alloys substantially had an orthorhombic {α }\\prime\\prime phase with a fine, acicular morphology. The content of equi-axed β phase continued to increase with increased Zr content at the expense of {α }\\prime\\prime phase. The threshold Zr content for the formation of β phase in the ST Ti-7.5Mo-xZr alloys was apparently higher than that in the AC Ti-7.5Mo-xZr alloys. The β granular structure was revealed in ST Ti-7.5Mo-5Zr alloy, which increased with increased Zr content. Unlike AC Ti-7.5Mo-9Zr alloy, within each grain of ST Ti-7.5Mo-9Zr alloy were still observed a significant portion of {α }\\prime\\prime morphology. AC Ti-7.5Mo alloy had the lowest YS, lowest tensile modulus and highest elongation among all AC Ti-7.5Mo-xZr alloys. When Zr content increased, both YS and modulus significantly increased while the elongation significantly decreased. Compared to AC Ti-7.5Mo alloy, AC Ti-7.5Mo-9Zr alloy had almost double YS, indicating the effectiveness of Zr-induced strengthening in the AC Ti-7.5Mo-xZr alloys. Compared to AC Ti-7.5Mo, ST Ti-7.5Mo alloys had lower YS, UTS and tensile modulus with almost the same elongation. All the XRD, metallography and tensile test results consistently indicated that the presence of Zr could accelerate the formation of β phase and effectively strengthen the AC Ti-7.5Mo-xZr alloys. A phenomenon of delayed β formation and delayed strengthening was noted in the ST Ti-7.5Mo-xZr alloys, compared to the AC Ti-7.5Mo-xZr alloys.

  10. Anomalous Thermal Expansion of HoCo0.5Cr0.5O3 Probed by X-ray Synchrotron Powder Diffraction.

    PubMed

    Hreb, Vasyl; Vasylechko, Leonid; Mykhalichko, Vitaliya; Prots, Yurii

    2017-12-01

    Mixed holmium cobaltite-chromite HoCo 0.5 Cr 0.5 O 3 with orthorhombic perovskite structure (structure type GdFeO 3 , space group Pbnm) was obtained by solid state reaction of corresponding oxides in air at 1373 K. Room- and high-temperature structural parameters were derived from high-resolution X-ray synchrotron powder diffraction data collected in situ in the temperature range of 300-1140 K. Analysis of the results obtained revealed anomalous thermal expansion of HoCo 0.5 Cr 0.5 O 3 , which is reflected in a sigmoidal temperature dependence of the unit cell parameters and in abnormal increase of the thermal expansion coefficients with a broad maxima near 900 K. Pronounced anomalies are also observed for interatomic distances and angles within Co/CrO 6 octahedra, tilt angles of octahedra and atomic displacement parameters. The observed anomalies are associated with the changes of spin state of Co 3+ ions and insulator-metal transition occurring in HoCo 0.5 Cr 0.5 O 3 .

  11. Anomalous Thermal Expansion of HoCo0.5Cr0.5O3 Probed by X-ray Synchrotron Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Hreb, Vasyl; Vasylechko, Leonid; Mykhalichko, Vitaliya; Prots, Yurii

    2017-07-01

    Mixed holmium cobaltite-chromite HoCo0.5Cr0.5O3 with orthorhombic perovskite structure (structure type GdFeO3, space group Pbnm) was obtained by solid state reaction of corresponding oxides in air at 1373 K. Room- and high-temperature structural parameters were derived from high-resolution X-ray synchrotron powder diffraction data collected in situ in the temperature range of 300-1140 K. Analysis of the results obtained revealed anomalous thermal expansion of HoCo0.5Cr0.5O3, which is reflected in a sigmoidal temperature dependence of the unit cell parameters and in abnormal increase of the thermal expansion coefficients with a broad maxima near 900 K. Pronounced anomalies are also observed for interatomic distances and angles within Co/CrO6 octahedra, tilt angles of octahedra and atomic displacement parameters. The observed anomalies are associated with the changes of spin state of Co3+ ions and insulator-metal transition occurring in HoCo0.5Cr0.5O3.

  12. Enhanced torsional actuation and stress coupling in Mn-modified 0.93(Na 0.5Bi 0.5TiO 3)-0.07BaTiO 3 lead-free piezoceramic system

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

    Berik, Pelin; Maurya, Deepam; Kumar, Prashant

    This paper is concerned with the development of a piezoelectric d 15 shear-induced torsion actuator made of a lead-free piezoceramic material exhibiting giant piezoelectric shear stress coefficient (e 15) and piezoelectric transverse shear actuation force comparable to that of leadbased shear-mode piezoceramics. The Mn-modified 0.93(Na 0.5Bi 0.5TiO 3)-0.07BaTiO 3 (NBT-BTMn) composition exhibited excellent properties as a torsional transducer with piezoelectric shear stress coefficient on the order of 11.6 C m –2. The torsional transducer, consisting of two oppositely polarized NBT-BT-Mn d 15 mode piezoceramic shear patches, provided a rate of twist of 0.08 mm m –1 V –1 under quasi-staticmore » 150 V drive. The high value of piezoelectric shear d 15 coefficient in NBT-BT-Mn sample further demonstrated its potential in practical applications. Lastly, these results confirm that the lead-free piezoceramics can be as effective as their lead-based counterparts.« less

  13. Enhanced torsional actuation and stress coupling in Mn-modified 0.93(Na 0.5Bi 0.5TiO 3)-0.07BaTiO 3 lead-free piezoceramic system

    DOE PAGES

    Berik, Pelin; Maurya, Deepam; Kumar, Prashant; ...

    2017-01-09

    This paper is concerned with the development of a piezoelectric d 15 shear-induced torsion actuator made of a lead-free piezoceramic material exhibiting giant piezoelectric shear stress coefficient (e 15) and piezoelectric transverse shear actuation force comparable to that of leadbased shear-mode piezoceramics. The Mn-modified 0.93(Na 0.5Bi 0.5TiO 3)-0.07BaTiO 3 (NBT-BTMn) composition exhibited excellent properties as a torsional transducer with piezoelectric shear stress coefficient on the order of 11.6 C m –2. The torsional transducer, consisting of two oppositely polarized NBT-BT-Mn d 15 mode piezoceramic shear patches, provided a rate of twist of 0.08 mm m –1 V –1 under quasi-staticmore » 150 V drive. The high value of piezoelectric shear d 15 coefficient in NBT-BT-Mn sample further demonstrated its potential in practical applications. Lastly, these results confirm that the lead-free piezoceramics can be as effective as their lead-based counterparts.« less

  14. Approaching Piezoelectric Response of Pb-Piezoelectrics in Hydrothermally Synthesized Bi0.5(Na1- xK x)0.5TiO3 Nanotubes.

    PubMed

    Ghasemian, Mohammad Bagher; Rawal, Aditya; Liu, Yun; Wang, Danyang

    2018-06-20

    A large piezoelectric coefficient of 76 pm/V along the diameter direction, approaching that of lead-based piezoelectrics, is observed in hydrothermally synthesized Pb-free Bi 0.5 (Na 0.8 K 0.2 ) 0.5 TiO 3 nanotubes. The 30-50 nm diameter nanotubes are formed through a scrolling and wrapping mechanism without the need of a surfactant or template. A molar ratio of KOH/NaOH = 0.5 for the mineralizers yields the Na/K ratio of ∼0.8:0.2, corresponding to an orthorhombic-tetragonal (O-T) phase boundary composition. X-ray diffraction patterns along with transmission electron microscopy analysis ascertain the coexistence of orthorhombic and tetragonal phases with (110) and (001) orientations along the nanotube length direction, respectively. 23 Na NMR spectroscopy confirms the higher degree of disorder in Bi 0.5 (Na 1- x K x ) 0.5 TiO 3 nanotubes with O-T phase coexistence. These findings present a significant advance toward the application of Pb-free piezoelectric materials.

  15. New Observations of Soft X-ray (0.5-5 keV) Solar Spectra

    NASA Astrophysics Data System (ADS)

    Caspi, A.; Woods, T. N.; Mason, J. P.; Jones, A. R.; Warren, H. P.

    2013-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable on many time scales. However, the actual solar soft X-ray (SXR) (0.5-5 keV) spectrum is not well known, particularly during solar quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include high-resolution but very narrow-band spectra from crystal spectrometers (e.g., Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g., GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with moderate energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and SAX on MESSENGER, although they did not extend to energies below ~1 keV. We present observations of solar SXR emission obtained using new instrumentation flown on recent SDO/EVE calibration rocket underflights. The photon-counting spectrometer, a commercial Amptek X123 with a silicon drift detector and an 8 μm Be window, measures the solar disk-integrated SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution and 1 s cadence. A novel imager, a pinhole X-ray camera using a cooled frame-transfer CCD (15 μm pixel pitch), Ti/Al/C filter, and 5000 line/mm Au transmission grating, images the full Sun in multiple spectral orders from ~0.1 to ~5 nm with ~10 arcsec/pixel and ~0.01 nm/pixel spatial and spectral detector scales, respectively, and 10 s cadence. These instruments are prototypes for future CubeSat missions currently being developed. We present new results of solar observations on 04 October 2013 (NASA sounding rocket 36.290). We compare with previous results from 23 June 2012 (NASA sounding rocket 36.286), during which solar activity was low and no signal was observed above ~4 keV. We compare our spectral and imaging measurements with spectra and broadband irradiances from other instruments, including SDO/EVE, GOES/XRS, TIMED

  16. A 2 TiO 5 (A = Dy, Gd, Er, Yb) at High Pressure

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

    Park, Sulgiye; Rittman, Dylan R.; Tracy, Cameron L.

    The structural evolution of lanthanide A2TiO5 (A = Dy, Gd, Yb, and Er) at high pressure is investigated using synchrotron X-ray diffraction. The effects of A-site cation size and of the initial structure are systematically examined by varying the composition of the isostructural lanthanide titanates, and the structure of dysprosium titanate polymorphs (orthorhombic, hexagonal and cubic), respectively. All samples undergo irreversible high pressure phase transformations, but with different onset pressures depending on the initial structure. While individual phase exhibits different phase transformation histories, all samples commonly experience a sluggish transformation to a defect cotunnite-like (Pnma) phase for a certain pressuremore » range. Orthorhombic Dy2TiO5 and Gd2TiO5 form P21am at pressures below 9 GPa and Pnma above 13 GPa. Pyrochlore-type Dy2TiO5 and Er2TiO5 as well as defect-fluorite-type Yb2TiO5 form Pnma at ~ 21 GPa, followed by Im-3m. Hexagonal Dy2TiO5 forms Pnma directly, although a small amount of remnants of hexagonal Dy2TiO5 is observed even at the highest pressure (~ 55 GPa) reached, indicating a kinetic limitations in the hexagonal Dy2TiO5 phase transformations at high pressure. Decompression of these materials leads to different metastable phases. Most interestingly, a high pressure cubic X-type phase (Im-3m) is confirmed using highresolution transmission electron microscopy on recovered pyrochlore-type Er2TiO5. The kinetic constraints on this metastable phase yield a mixture of both the X-type phase and amorphous domains upon pressure release. This is the first observation of an X-type phase for an A2BO5 composition at high pressure.« less

  17. Synthesis and photochemical properties of ferrotitanate In4FeTi3O13.5 with layer structure

    NASA Astrophysics Data System (ADS)

    Liu, Xuanxuan; Huang, Yanlin; Qin, Chuanxiang; Seo, Hyo Jin

    2018-01-01

    In4FeTi3O13.5 (InTi0.75Fe0.25O3.375) semiconductor was prepared via sol-gel citrate-complexation synthesis. This ferrotitanate derives from a solid-solution with InFeO3:In2Ti2O7 = 2:3. Phase formation and crystal structure of the sample were confirmed via XRD Rietveld refinement. Structural analyses indicated that there were two dimensional layers in the structure. The mutual repulsion in the layers induces great displacements of oxygen ions. The optical properties of In4FeTi3O13.5 nanoparticles were investigated. The direct allowed band gap (2.56 eV) shows a characteristic charge-transfer (CT) transitions of (O2p + Fe3d) → (Ti/Fe)3d in visible-light region. The band structure and energy positions were discussed. In4FeTi3O13.5 nanoparticles are demonstrated to be efficient for the photodegradation of Rhodamine B (RhB) under visible light irradiation (λ > 420 nm). The photocatalytic activities were attributed to the special layer structure and the catalytic mediators of multivalent Ti4+/3+ and Fe3+/2+ confirmed by XPS measurements.

  18. Trap depth and color variation of Ce3+-Cr3+ co-doped Gd3(Al,Ga)5O12 garnet persistent phosphors

    NASA Astrophysics Data System (ADS)

    Asami, Kazuki; Ueda, Jumpei; Tanabe, Setsuhisa

    2016-12-01

    Persistent luminescent properties in Ce3+-Cr3+ codoped Gd3Al5-xGaxO12 garnet (GAGG:Ce-Cr) solid solution have been investigated. The persistent luminescent color is shifted from orange to yellowish green with increasing Ga content because Ce3+: 5d level splitting becomes much weaker. The depth of electron trap introduced by Cr codoping was estimated from the intense thermoluminescence glow peak by the initial rise method. The trap depth decreases from 0.56 eV to 0.29 eV with increasing Ga content. The shift can be explained by downshift of bottom of conduction band. From the persistent luminescence decay curve measurement after ceasing 450 nm blue illumination, the samples with x = 2.5 exhibited the longest persistent luminescence for 405 min until the luminance becomes 2 mcd/m2 in GAGG:Ce-Cr phosphors.

  19. 42 CFR 63a.5 - How to apply for a training grant.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false How to apply for a training grant. 63a.5 Section 63a.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.5 How to apply for a training grant...

  20. 42 CFR 63a.5 - How to apply for a training grant.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false How to apply for a training grant. 63a.5 Section 63a.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.5 How to apply for a training grant...

  1. 42 CFR 63a.5 - How to apply for a training grant.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false How to apply for a training grant. 63a.5 Section 63a.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.5 How to apply for a training grant...

  2. 42 CFR 63a.5 - How to apply for a training grant.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false How to apply for a training grant. 63a.5 Section 63a.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.5 How to apply for a training grant...

  3. 42 CFR 63a.5 - How to apply for a training grant.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false How to apply for a training grant. 63a.5 Section 63a.5 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.5 How to apply for a training grant...

  4. Preparation of directionally solidified BaTi2O5-Ba6Ti17O40 eutectic by the floating zone method

    NASA Astrophysics Data System (ADS)

    Shiga, K.; Katsui, H.; Goto, T.

    2017-02-01

    The BaTi2O5-Ba6Ti17O40 eutectic (BaO-68.7 mol% TiO2) was directionally solidified by the floating zone (FZ) method and crystalline phases, microstructures and orientation were investigated. Ba6Ti17O40 with faceted rod-like shape was dispersed in the BaTi2O5 matrix. The growth directions of BaTi2O5 and Ba6Ti17O40 were parallel to the b and a axis, respectively, and the orientation relations were BaTi2O5 (010)//Ba6Ti17O40(60 2 ̅) and BaTi2O5 (001)//Ba6Ti17O40 (001).

  5. 47 CFR 5.63 - Supplementary statements required.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... experimental authorization involving a satellite system must submit a description of the design and operational... 5.63 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EXPERIMENTAL RADIO SERVICE (OTHER... for an authorization in the Experimental Radio Service must enclose with the application a narrative...

  6. 47 CFR 5.63 - Supplementary statements required.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... experimental authorization involving a satellite system must submit a description of the design and operational... 5.63 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EXPERIMENTAL RADIO SERVICE (OTHER... for an authorization in the Experimental Radio Service must enclose with the application a narrative...

  7. 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.

  8. Hot Deformation of Ti-6Al-4V Single-Colony Samples (Preprint)

    DTIC Science & Technology

    2008-02-01

    Journal Article Preprint 4 . TITLE AND SUBTITLE HOT DEFORMATION OF Ti-6Al-4V SINGLE-COLONY SAMPLES (PREPRINT) 5a. CONTRACT NUMBER In-house 5b...GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62102F 6 . AUTHOR(S) A.A. Salem (Universal Technology Corp.) S.L. Semiatin (AFRL/RXLMP) 5d. PROJECT...strength, corrosion resistance, and low density, Ti-6Al-4V is the most commonly used alpha/beta titanium alloy. It accounts for approximately 80

  9. Specific Volumes of the Zr(41.2)Ti(13.8)Cu(12.5)Ni(10.0)Be(22.5) Alloy in the Liquid, Glass, and Crystalline States

    NASA Technical Reports Server (NTRS)

    Ohsaka, K.; Chung, S. K.; Rhim, W. K.; Johnson, W. L.; Peker, A.; Scruggs, D.

    1997-01-01

    The specific volumes of the Zr(41.2)Ti(3.8)Cu(2.5)Ni(10.0)Be(22.5) alloy as a function of temperature, T, are determined by employing an image digitizing technique and numerical calculation methods applied to the electrostatically levitated spherical alloy. The linear fitting of the volumes of the alloy in the liquid, V(sub l), glass, V(sub g) and crystalline V(sub c), states in the temperature ranges shown in parentheses are V(sub l)(T) = 0.1583 + 8.877 x 10(exp -6) T(cu cm/g) (700-1300 K);V(sub g)(T) = 0.1603 + 5.528 x 10(exp -6) T (400-550 K);V(sub c)(T) = 0.1583 + 6.21 x 10(exp -6)T(400-850 K). The average volume thermal expansion coefficients within the temperature ranges are determined to be 5.32, 3.39. and 3.83 x 10(exp -5) (1/K) for the liquid, glass, and crystalline states, respectively.

  10. Hardness and Second Phase Percentage of Ni-Ti-Hf Compounds After Heat Treatment at 700C

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.

    2017-01-01

    The Vickers hardness and second phase precipitation of three ternary intermetallic Ni-Ti-Hf compounds containing either 1, 3 or 5 at.% Hf were compared to 60-Nitinol (55 at.% Ni - 45 at.% Ti). Heat treatment either at 700 C or with a subsequent aging step, hardened the 3 and 5 at.% Hf-containing ternaries to approximately 620 HV (56 HRC). Heat treatment increased the hardness of the 1 at.% Hf compound by more than 25 percent. Average hardness of the 3 and 5 at.% Hf ternaries, though higher than that of the binary Ni-Ti or the Ni-Ti-Hf compound containing 1 at.% Hf, appeared to be fairly insensitive to the different heat treatments. There was a drastic reduction of fatigue-enhancing second phase precipitates for the 5 at.% Hf ternaries compared to the other compounds. These results should guide materials selection for development of aerospace componentry.

  11. Using the Markov chain Monte Carlo method to study the physical properties of GeV-TeV BL Lac objects

    NASA Astrophysics Data System (ADS)

    Qin, Longhua; Wang, Jiancheng; Yang, Chuyuan; Yuan, Zunli; Mao, Jirong; Kang, Shiju

    2018-01-01

    We fit the spectral energy distributions (SEDs) of 46 GeV-TeV BL Lac objects in the frame of leptonic one-zone synchrotron self-Compton (SSC) model and investigate the physical properties of these objects. We use the Markov chain Monte Carlo (MCMC) method to obtain the basic parameters, such as magnetic field (B), the break energy of the relativistic electron distribution (γ ^' }b), and the electron energy spectral index. Based on the modeling results, we support the following scenarios for GeV-TeV BL Lac objects. (1) Some sources have large Doppler factors, implying other radiation mechanism should be considered. (2) Compared with flat spectrum quasars (FSRQs), GeV-TeV BL Lac objects have weaker magnetic fields and larger Doppler factors, which cause the ineffective cooling and shift the SEDs to higher bands. Their jet powers are around 4.0 × 1045 erg s-1, compared with radiation power, 5.0 × 1042 erg s-1, indicating that only a small fraction of jet power is transformed into the emission power. (3) For some BL Lacs with large Doppler factors, their jet components could have two substructures, e.g., the fast core and the slow sheath. For most GeV-TeV BL Lacs, Kelvin-Helmholtz instabilities are suppressed by their higher magnetic fields, leading to micro-variability or intro-day variability in the optical bands. (4) Combined with a sample of FSRQs, an anti-correlation between the peak luminosity, Lpk, and the peak frequency, νpk, is obtained, favoring the blazar sequence scenario. In addition, an anti-correlation between the jet power, Pjet, and the break Lorentz factor, γb, also supports the blazar sequence.

  12. Phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics

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

    Peng, Wei; Mao, Chaoliang; Liu, Zhen

    2015-03-02

    The phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} lead-free ceramics were investigated systematically. The loss tangent of poled sample shows a broad peak when heating to about 80 °C, i.e., depolarization temperature T{sub d}. The polarization-electric field hysteresis loops at different temperature exhibit the feature of ferroelectric (FE)- antiferroelectric (AFE) phase transition and the co-existence of FE and AFE phase. The pyroelectric coefficients curve confirms its diffusion behaviors. The initial hysteresis loop and switching current curves under T{sub d} indicate the co-existence of FE and AFE phase. The domain morphology of transmission electron microscopy supports the co-existence of FE andmore » AFE phase. Our work not only exhibit that the FE and AFE phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics but also they may be helpful for further investigation on lead-free ceramics.« less

  13. 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.

  14. TiO2/water Nanofluid Heat Transfer in Heat Exchanger Equipped with Double Twisted-Tape Inserts

    NASA Astrophysics Data System (ADS)

    Eiamsa-ard, S.; Ketrain, R.; Chuwattanakul, V.

    2018-05-01

    Nowadays, heat transfer enhancement plays an important role in improving efficiency of heat transfer and thermal systems for numerous areas such as heat recovery processes, chemical reactors, air-conditioning/refrigeration system, food engineering, solar air/water heater, cooling of high power electronics etc. The present work presents the experimental results of the heat transfer enhancement of TiO2/water nanofluid in a heat exchanger tube fitted with double twisted tapes. The study covered twist ratios of twisted tapes (y/w) of 1.5, 2.0, and 2.5) while the concentration of the nanofluid was kept constant at 0.05% by volume. Observations show that heat transfer, friction loss and thermal performance increase as twist ratio (y/w) decreases. The use of the nanofluid in the tube equipped with the double twisted-tapes with the smallest twist ratio (y/w = 1.5) results in the increases of heat transfer rates and friction factor up to 224.8% and 8.98 times, respectively as compared to those of water. In addition, the experimental results performed that double twisted tapes induced dual swirling-flows which played an important role in improving fluid mixing and heat transfer enhancement. It is also observed that the TiO2/water nanofluid was responsible for low pressure loss behaviors.

  15. Glassy and Metastable Crystalline BaTi2O5 by Containerless Processing

    NASA Astrophysics Data System (ADS)

    Yoda, Shinichi; Kentei Yu, Yu; Kumar, Vijaya; Kameko, Masashi

    Many efforts have been devoted to forming bulk glass from the melt of ferroelectric crystalline materials without adding any network-forming oxides such as SiO2 due to the potential for producing transparent glass ceramics with high dielectric constant and enhanced piezoelectric, pyroelectric and electro-optic use. The containerless processing is an attractive synthesis tech-nique as it can prevent melt contamination, minimize heterogeneous nucleation, and allow melt to achieve deep undercooling for forming metastable and glassy materials. We have fabricated a new ferroelectric materiel BaTi2 O5 [1] as bulk glass from melt by us-ing containerless processing and studied the phase relationship between microstructure and ferroelectric properties of BaTi2 O5 [2]. The structures of glassy and metastable crystalline BaTi2 O5 fabricated by the containerless pro-cessing were comprehensively investigated by combined X-ray and neutron diffractions, XANES analyses and computer simulations [3]. The 3-dimensional atomic structure of glassy BaTi2 O5 (g-BaTi2 O5 ), simulated by Reverse Monte Carlo (RMC) modelling on diffraction data, shows that extremely distorted TiO5 polyhedra interconnected with both corner-and edge-shared oxy-gen, formed a higher packing density structure than that of conventional silicate glass linked with only corner-sharing of SiO4 polyhedra. In addition, XANES measurement reveales that five-coordinated TiO5 polyhedra were formable in the crystallized metastable a-and b-BaTi2 O5 phases. The structure of metastable b-BaTi2 O5 was solved by ab initio calculation, and refined by Rietveld refinement as group Pnma with unit lattices a = 10.23784 ˚, b = 3.92715 ˚, c A A = 10.92757 A ˚. Our results show that the glass-forming ability enhanced by containerless pro-cessing, not by `strong glass former', fabricated new bulk oxide glasses with peculiar structures and properties. The intermediate-range structure of g-BaTi2 O5 and the crystalline structure of

  16. Study on the failure temperature of Ti/Pt/Au and Pt5Si2-Ti/Pt/Au metallization systems

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Han, Jianqiang; Yin, Yijun; Dong, Lizhen; Niu, Wenju

    2017-09-01

    The Ti/Pt/Au metallization system has an advantage of resisting KOH or TMAH solution etching. To form a good ohmic contact, the Ti/Pt/Au metallization system must be alloyed at 400 °C. However, the process temperatures of typical MEMS packaging technologies, such as anodic bonding, glass solder bonding and eutectic bonding, generally exceed 400 °C. It is puzzling if the Ti/Pt/Au system is destroyed during the subsequent packaging process. In the present work, the resistance of doped polysilicon resistors contacted by the Ti/Pt/Au metallization system that have undergone different temperatures and time are measured. The experimental results show that the ohmic contacts will be destroyed if heated to 500 °C. But if a 20 nm Pt film is sputtered on heavily doped polysilicon and alloyed at 700 °C before sputtering Ti/Pt/Au films, the Pt5Si2-Ti/Pt/Au metallization system has a higher service temperature of 500 °C, which exceeds process temperatures of most typical MEMS packaging technologies. Project supported by the National Natural Science Foundation of China (No. 61376114).

  17. Effects of hot-salt stress corrosion on titanium alloys.

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1972-01-01

    Susceptibility of titanium alloys to hot-salt stress-corrosion cracking increased as follows: Ti-2Al-11Sn-5Zr-1Mo-0.2Si (679), Ti-6Al-2Sn-4Zr-2Mo (6242), Ti-6Al-4V (64), Ti-6Al-4V-3Co (643), Ti-8Al-1Mo-1V (811), and Ti-13V-11Cr-3Al (13-11-3). The Ti-5Al-6Sn-2Zr-1Mo-0.25Si (5621S) alloy was both the least and most susceptible, depending on heat treatment. Such rankings can be drastically altered by heat-to-heat variations and processing conditions. Residual compressive stresses reduce susceptibility to stress-corrosion. Detection of substantial concentrations of hydrogen in all corroded alloys confirmed the generality of a previously proposed hydrogen embrittlement mechanism.

  18. Soft ferromagnetism in mixed valence Sr(1-x)La(x)Ti(0.5)Mn(0.5)O₃ perovskites.

    PubMed

    Qasim, Ilyas; Blanchard, Peter E R; Kennedy, Brendan J; Ling, Chris D; Jang, Ling-Yun; Kamiyama, Takashi; Miao, Ping; Torii, Shuki

    2014-05-14

    The structural, magnetic and electrical properties of the mixed Ti-Mn oxides Sr(1-x)La(x)Ti(0.5)Mn(0.5)O3 (0 ≤ x ≤ 0.5) are reported. At room temperature the oxides have a cubic structure in space group Pm3m for x ≤ 0.25 and rhombohedral in R3c for 0.3 ≤ x ≤ 0.50. X-ray absorption spectroscopic measurements demonstrate the addition of La(3+) is compensated by the partial reduction of Mn(4+) to Mn(3+). Variable temperature neutron diffraction measurements show that cooling Sr(0.6)La(0.4)Ti(0.5)Mn(0.5)O3 results in a first order transition from rhombohedra to an orthorhombic structure in Imma. Complex magnetic behaviour is observed. The magnetic behaviour of the mixed valent (Mn(3+/4+)) examples is dominated by ferromagnetic interactions, although cation disorder frustrates long range magnetic ordering.

  19. Heat treatment effects on toughness of 9Cr-1MoVNb and 12Cr-1MoVW steels irradiated at 365°C

    NASA Astrophysics Data System (ADS)

    Klueh, R. L.; Alexander, D. J.

    1992-09-01

    The 9Cr-1MoVNb and 12Cr-1MoVW steels were austenitized at 1040 and 1100°C to produce different prior austenite grain sizes, after which they were given different tempering treatments (1 h at 760°C or 2.5 h at 780°C). Subsize Charpy impact specimens from these materials were irradiated at 365°C up to 5 dpa. For 9Cr-1MoVNb steel in the unirradiated condition, the smaller the prior austenite grain size and the higher the tempering temperature, the lower the ductile-brittle transition temperature (DBTT). Regardless of the DBTT in the unirradiated condition, however, the DBTT shift for 9Cr-1MoVNb steel due to irradiation was the same for all heat treatments. This means heat treatment can be used to ensure a lower DBTT before and after irradiation. The 12Cr-1MoVW steel showed little effect of heat treatment on DBTT in the unirradiated condition, and the shift in DBTT was relatively constant. Thus, it appears that heat treatment cannot be used to reduce the effect of irradiation on DBTT for this steel.

  20. The structure and energetics of Cr(CO)6 and Cr(CO)5

    NASA Technical Reports Server (NTRS)

    Barnes, Leslie A.; Liu, Bowen; Lindh, Roland

    1992-01-01

    The geometric structure of Cr(CO)6 is optimized at the modified coupled pair functional (MCPF), single and double excitation coupled-cluster (CCSD) and CCSD(T) levels of theory (including a perturbational estimate for connected triple excitations), and the force constants for the totally symmetric representation are determined. The geometry of Cr(CO)5 is partially optimized at the MCPF, CCSD, and CCSD(T) levels of theory. Comparison with experimental data shows that the CCSD(T) method gives the best results for the structures and force constants, and that remaining errors are probably due to deficiencies in the one-particle basis sets used for CO. The total binding energies of Cr(CO)6 and Cr(CO)5 are also determined at the MCPF, CCSD, and CCSD(T) levels of theory. The CCSD(T) method gives a much larger total binding energy than either the MCPF or CCSD methods. An analysis of the basis set superposition error (BSSE) at the MCPF level of treatment points out limitations in the one-particle basis used. Calculations using larger basis sets reduce the BSSE, but the total binding energy of Cr(CO)6 is still significantly smaller than the experimental value, although the first CO bond dissociation energy of Cr(CO)6 is well described. An investigation of 3s3p correlation reveals only a small effect. In the largest basis set, the total CO binding energy of Cr(CO)6 is estimated to be 140 kcal/mol at the CCSD(T) level of theory, or about 86 percent of the experimental value. The remaining discrepancy between the experimental and theoretical value is probably due to limitations in the one-particle basis, rather than limitations in the correlation treatment. In particular an additional d function and an f function on each C and O are needed to obtain quantitative results. This is underscored by the fact that even using a very large primitive set (1042 primitive functions contracted to 300 basis functions), the superposition error for the total binding energy of Cr(CO)6 is 22

  1. Magnetism of hexagonal Mn{sub 1.5}X{sub 0.5}Sn (X = Cr, Mn, Fe, Co) nanomaterials

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

    Fuglsby, R.; Kharel, P., E-mail: parashu.kharel@sdstate.edu; Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588

    2015-05-07

    Mn{sub 1.5}X{sub 0.5}Sn (X = Cr, Mn, Fe, Co) nanomaterials in the hexagonal Ni{sub 2}In-type crystal structure have been prepared using arc-melting and melt spinning. All the rapidly quenched Mn{sub 1.5}X{sub 0.5}Sn alloys show moderate saturation magnetizations with the highest value of 458 emu/cm{sup 3} for Mn{sub 1.5}Fe{sub 0.5}Sn, but their Curie temperatures are less than 300 K. All samples except the Cr containing one show spin-glass-like behavior at low temperature. The magnetic anisotropy constants calculated from the high-field magnetization curves at 100 K are on the order of 1 Merg/cm{sup 3}. The vacuum annealing of the ribbons at 550 °C significantly improved theirmore » magnetic properties with the Curie temperature increasing from 206 K to 273 K for Mn{sub 1.5}Fe{sub 0.5}Sn.« less

  2. Synthesis of As-Cast Ti-Al-V Alloy from Titanium-Rich Material by Thermite Reduction

    NASA Astrophysics Data System (ADS)

    Cheng, Chu; Dou, Zhi He; Zhang, Ting An; Zhang, Hui Jie; Yi, Xin; Su, Jian Ming

    2017-10-01

    We present a novel methodology for preparing as-cast Ti-Al-V alloy directly from titanium-rich material through a thermite reduction. The new method is shown to be feasible through a thermodynamics and dynamics analysis. The as-cast Ti-Al-V alloys synthesized from titanium dioxide, rutile, and high-titanium slag were analyzed by an x-ray diffractometer, a scanning electron microscope, an inductively coupled plasma emission spectrometer, and an oxygen/nitrogen/hydrogen analyzer. The results indicate that the alloy is composed of a Ti-Al-V matrix and Al2O3 inclusions. The Al and V contents in the matrix are close to the mass ratio of Ti-6Al-4V (Al: 5.5-6.8 wt.%, V: 3.5-4.5 wt.%). The Si and Fe in the alloys synthesized from rutile and high-titanium slag can be used as alloying elements in low-cost titanium alloys. The present method is expected to be useful for preparing Ti-Al-V alloys at a low production cost.

  3. Electrochemical Characterization of a Low Modulus Ti-35.5Nb-7.3Zr-5.7Ta Alloy in a Simulated Body Fluid Using Eis for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Bhola, R.; Bhola, S. M.; Mishra, B.; Ayers, R. A.; Olson, D. L.

    2011-06-01

    Electrochemical characterization of the low modulus Ti-35.5Nb-7.3Zr-5.7Ta beta alloy (TNZT) has been performed in phosphate buffer saline solution at 37 °C using the non destructive electrochemical impedance spectroscopy technique. Measurements were performed at various immersion intervals at the open circuit potential (OCP), which was also monitored with time. Results obtained for TNZT alloy have been compared with those for the commercially used Ti-6Al-4V mixed alloy (Ti64) and the commercially pure titanium (Ti2) alpha alloy. Potentiodynamic polarization was performed to supplement the data obtained from EIS analysis. The TNZT alloy exhibits a two time constant impedance response, whereas the Ti64 and Ti2 alloys display a one time constant behavior. Human fetal osteoblast cells show a better adhesion and a higher cell count for the TNZT alloy compared to the other two alloys. The present investigation is an effort to understand the correlation between the electrochemical, morphological and cellular characteristics of titanium alloys to qualify them for implant applications.

  4. Pilot-scale evaluation of a novel TiO2-supported V2O5 catalyst for DeNOx at low temperatures at a waste incinerator.

    PubMed

    Jung, Hyounduk; Park, Eunseuk; Kim, Minsu; Jurng, Jongsoo

    2017-03-01

    The removal of NOx by catalytic technology at low temperatures is significant for treatment of flue gas in waste incineration plants, especially at temperatures below 200°C. A novel highly active TiO 2 -supported vanadium oxide catalyst at low temperatures (200-250°C) has been developed for the selective catalytic reduction (SCR) de-NOx process with ammonia. The catalyst was evaluated in a pilot-scale equipment, and the results were compared with those obtained in our previous work using laboratory scale (small volume test) equipment as well as bench-scale laboratory equipment. In the present work, we have performed our experiments in pilot scale equipment using a part of effluent flue gas that was obtained from flue gas cleaning equipment in a full-scale waste incineration plant in South Korea. Based on our previous work, we have prepared a TiO 2 -supported V 2 O 5 catalyst coated (with a loading of 7wt% of impregnated V 2 O 5 ) on a honeycomb cordierite monolith to remove NOx from a waste incinerator flue gas at low temperatures. The NOx (nitrogen oxides) removal efficiency of the SCR catalyst bed was measured in a catalyst fixed-bed reactor (flow rate: 100m 3 h -1 ) using real exhaust gas from the waste incinerator. The experimental results showed that the V 2 O 5 /TiO 2 SCR catalyst exhibited good DeNOx performance (over 98% conversion at an operating temperature of 300°C, 95% at 250°C, and 70% at 200°C), and was much better than the performance of commercial SCR catalysts (as low as 55% conversion at 250°C) under the same operating conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Nitridation-driven conductive Li4Ti5O12 for lithium ion batteries.

    PubMed

    Park, Kyu-Sung; Benayad, Anass; Kang, Dae-Joon; Doo, Seok-Gwang

    2008-11-12

    To modify oxide structure and introduce a thin conductive film on Li4Ti5O12, thermal nitridation was adopted for the first time. NH3 decomposes surface Li4Ti5O12 to conductive TiN at high temperature, and surprisingly, it also modifies the surface structure in a way to accommodate the single phase Li insertion and extraction. The electrochemically induced Li4+deltaTi5O12 with a TiN coating layer shows great electrochemical properties at high current densities.

  6. Effect of Cr3+ concentration on structural and optical properties of TiO2:Cr3+ anatase and rutile phases

    NASA Astrophysics Data System (ADS)

    Loan, Trinh Thi; Bang, Ngac An; Huong, Vu Hoang; Long, Nguyen Ngoc

    2017-07-01

    TiO2 powders doped with different amounts of Cr3+ions (from 0 to 10 mol%) have been prepared by hydrothermal technique. TiO2:Cr3+ powders were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, diffuse reflection, absorption, photoluminescence and photoluminescence excitation spectra. The results showed that the Cr3+ dopant concentrations did not affect on the lattice constants of TiO2 crystal, but affected on shift and broadening of the Raman modes for both anatase and rutile phases. The band gap of both the anatase and rutile TiO2 host lattice was strongly decreased with increasing Cr3+ dopant concentration. The photoluminescence spectra of TiO2:Cr3+ anatase phase exhibited a weak narrow peak (the so-called R-line) at 698 nm, meanwhile those of TiO2:Cr3+ rutile phase consisted of a very intense narrow zero-phonon R-line at 695 nm assigned to the 2E(2G) → 4A2(4F) transition of Cr3+ ions in strong octahedral field and its phonon-sidebands. In particular, in the PL spectrum of TiO2:Cr3+ rutile phase is also observed an abroad emission band centered at 813 nm assigned to the 4T2(4F) → 4A2(4F) transition of ions Cr3+ in weak octahedral field.

  7. Complete Genome Sequence of the Avian Paramyxovirus Serotype 5 Strain APMV-5/budgerigar/Japan/TI/75.

    PubMed

    Hiono, Takahiro; Matsuno, Keita; Tuchiya, Kotaro; Lin, Zhifeng; Okamatsu, Masatoshi; Sakoda, Yoshihiro

    2016-09-22

    Here, we report the complete genome sequence of the avian paramyxovirus serotype 5 strain APMV-5/budgerigar/Japan/TI/75, which was determined using the Illumina MiSeq platform. The determined sequence shares 97% homology and similar genetic features with the previously known genome sequence of avian paramyxovirus serotype 5 strain APMV-5/budgerigar/Japan/Kunitachi/74. Copyright © 2016 Hiono et al.

  8. 36 CFR 63.5 - Federal Register publication of properties determined eligible.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Federal Register publication of properties determined eligible. 63.5 Section 63.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR DETERMINATIONS OF ELIGIBILITY FOR INCLUSION IN THE NATIONAL...

  9. 36 CFR 63.5 - Federal Register publication of properties determined eligible.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Federal Register publication of properties determined eligible. 63.5 Section 63.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR DETERMINATIONS OF ELIGIBILITY FOR INCLUSION IN THE NATIONAL...

  10. 36 CFR 63.5 - Federal Register publication of properties determined eligible.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Federal Register publication of properties determined eligible. 63.5 Section 63.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR DETERMINATIONS OF ELIGIBILITY FOR INCLUSION IN THE NATIONAL...

  11. 36 CFR 63.5 - Federal Register publication of properties determined eligible.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Federal Register publication of properties determined eligible. 63.5 Section 63.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR DETERMINATIONS OF ELIGIBILITY FOR INCLUSION IN THE NATIONAL...

  12. 36 CFR 63.5 - Federal Register publication of properties determined eligible.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Federal Register publication of properties determined eligible. 63.5 Section 63.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR DETERMINATIONS OF ELIGIBILITY FOR INCLUSION IN THE NATIONAL...

  13. Dielectric and Ferroelectric Properties of SrTiO3-Bi0.5Na0.5TiO3-BaAl0.5Nb0.5O3 Lead-Free Ceramics for High-Energy-Storage Applications.

    PubMed

    Yan, Fei; Yang, Haibo; Lin, Ying; Wang, Tong

    2017-11-06

    Pulsed capacitors require high-recoverable energy-storage density (W rec ) and high energy-storage efficiency (η), which can be realized through the selection and adjustment of the composition. In this work, (1 - x)SrTiO 3 -x(0.95Bi 0.5 Na 0.5 TiO 3 -0.05BaAl 0.5 Nb 0.5 O 3 ) [(1 - x)ST-x(BNT-BAN)] ceramics were successfully prepared via the pressureless solid-state reaction method. The dielectric constant increases gradually with the introduction of BNT-BAN and obtains a maximum value of 3430 with the composition of 0.4ST-0.6(BNT-BAN) at 100 Hz, which is 10.39 times higher than that of the pure ST sample (∼330). Dispersive relaxor behaviors and ferroelectric performances can be enhanced with the introduction of BNT-BAN. The composition of 0.5ST-0.5(BNT-BAN) exhibits a high W rec of 1.89 J/cm 3 as well as a high η of 77%. Therefore, the (1 - x)ST-x(BNT-BAN) systems are candidate materials for pulsed capacitor applications.

  14. Phase transformation in rapidly quenched Fe-Cr-Co-Mo-Ti-Si-B alloys

    NASA Astrophysics Data System (ADS)

    Zhukov, D. G.; Shubakov, V. S.; Zhukova, E. Kh; Gorshenkov, M. V.

    2018-03-01

    The research results of phase transformations in Fe-24Cr-16Co-3Mo-0.2Ti-1Si-B alloys (with a boron content of 1 to 3% by mass) obtained by rapid quenching are presented. The structure formation regularities during the melt spinning and during the subsequent crystallization annealing in rapidly quenched bands of the Fe-Cr-Co-Mo-Ti-Si-B system alloys were studied. The changes in the phase composition of the rapidly quenched Fe-Cr-Co-Mo-Ti- Si-B system alloys after quenching at various quench rates and at different boron concentrations in the alloys are studied. It is shown that during crystallization from an amorphous state, at temperatures above 570 °C, in addition to the α-phase, the σ-phase appears first, followed by the γ-phase. Heat treatment of rapidly quenched bands to high-coercive state was carried out. A qualitative assessment of magnetic properties in a high-coercivity state was carried out. An evaluation of the level of magnetic properties in a high-coercivity state allows us to conclude that the application of a magnetic field during crystallization from an amorphous state leads to anisotropy of the magnetic properties, that is, an anisotropic effect of thermo-magnetic treatment is detected.

  15. FERMI STUDY OF 5–300 GeV EMISSION FROM THE HIGH-MASS PULSAR BINARY PSR B1259-63/LS 2883

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

    Xing, Yi; Wang, Zhongxiang; Takata, Jumpei

    2016-09-01

    We report the results from our detailed analysis of the Fermi Large Area Telescope data for the pulsar binary PSR B1259−63/LS 2883. During the GeV flares that occurred when the pulsar was in the periastron passages, we have detected a 5–300 GeV component at ≃5 σ in emission from the binary. The detection verifies the presence of the component that has been marginally found in previous studies of the binary. Furthermore, we have discovered that this component was marginally present even in the quiescent state of the binary, specifically the mean anomaly phase 0.7–0.9. The component can be described bymore » a power law with a photon index Γ ∼ 1.4, and the flux in the flares is approximately one order of magnitude higher than that in quiescence. We discuss the origin of this component. It likely arises from the inverse-Compton process: due to the interaction between the winds from the pulsar and its massive companion, high-energy particles from the shock scatter the seed photons from the companion to GeV/TeV energies. Based on this scenario, model fits to the broad-band X-ray to TeV spectra of the binary in the flaring and quiescent states are provided.« less

  16. Characterization of Microstructure and Wear Resistance of PEO Coatings Containing Various Microparticles on Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Li, Xinyi; Dong, Chaofang; Zhao, Qing; Pang, Yu; Cheng, Fasong; Wang, Shuaixing

    2018-02-01

    Titania-based composite coatings were prepared by plasma electrolytic oxidation (PEO) treatment of Ti6Al4V alloy in electrolyte with α-Al2O3, Cr2O3 or h-BN microparticles in suspension. The microstructure, composition of PEO composite coatings were analyzed by SEM, EDS and XRD. The wear resistance of composite ceramic coatings was studied by ball-on-disk wear test at ambient temperature and 300 °C. The results showed that the addition of microparticles accelerated the growth rate of PEO coating and changed the microstructure and composition of PEO coating. PEO coating was porous and mainly composed of rutile-TiO2, anatase-TiO2 and Al2TiO5. PEO/α-Al2O3 (Cr2O3 or h-BN) composite coating only had small micropores and appeared some α-Al2O3 (Cr2O3 or h-BN) phase. Besides, the addition of α-Al2O3 (Cr2O3 or h-BN) microparticles greatly improved the wear resistance of PEO coating. At ambient temperature, abrasive wear dominated the wear behavior of PEO coating, but abrasive wear and adhesive peel simultaneously happened at 300 °C. Whether at ambient temperature or 300 °C, PEO composite coating had better wear resistance than PEO coating. Besides, PEO/h-BN composite coating outperformed other composite coatings regardless of the temperature.

  17. The response of CR-39 nuclear track detector to 1-9 MeV protons

    DOE PAGES

    Sinenian, N.; Rosenberg, M. J.; Manuel, M.; ...

    2011-10-28

    The response of CR-39 nuclear track detector (TasTrak®) to protons in the energy range of 0.92-9.28 MeV has been studied. Previous studies of the CR-39 response to protons have been extended by examining the piece-to-piece variability in addition to the effects of etch time and etchant temperature; it is shown that the shape of the CR-39 response curve to protons can vary from piece-to-piece. The effects due to the age of CR-39 have also been studied using 5.5 MeV alpha particles over a 5-year period. Track diameters were found to degrade with the age of the CR-39 itself rather thanmore » the age of the tracks, consistent with previous studies utilizing different CR-39 over shorter time periods.« less

  18. Plasma-Sprayed Ti6Al4V Alloy Composite Coatings Reinforced with In Situ Formed TiB-TiN

    NASA Astrophysics Data System (ADS)

    Anand, Akrity; Das, Mitun; Kundu, Biswanath; Balla, Vamsi Krishna; Bodhak, Subhadip; Gangadharan, S.

    2017-12-01

    Plasma spraying was used to deposit premixed Ti6Al4V + 15 wt.% BN powder on titanium substrate to fabricate Ti6Al4V matrix composite coatings reinforced with in situ synthesized TiB-TiN. The formation of in situ TiB-TiN reinforcements increased with plasma power. The in situ reaction appears to be complete under present experimental conditions but with considerable oxidation of Ti in the composite coatings. The hardness of composite coatings was 7 times higher (855HV), and the in vitro wear rate (2.4 × 10-5 mm3/N m) was one order of magnitude less than that of titanium substrate. However, the microstructural non-uniformity decreased the corrosion resistance of these composite coatings in Hank's balanced salt solution.

  19. The Influence of Cr3+ on TiO2 Crystal Growth and Photoactivity Properties

    NASA Astrophysics Data System (ADS)

    Wahyuningsih, S.; Hidayatika, W. N.; Sari, P. L.; Sari, P. P.; Hidayat, R.; Munawaroh, H.; Ramelan, A. H.

    2018-03-01

    The photocatalyst technology is an integrated combination of photochemical processes and catalysis in order to carry out a chemical transformation reaction. One of the semiconductor materials that have good photocatalytic activity is TiO2 anatase. This study aim to determine the effect of the Cr3+ addition on the growth of TiO2 rutile crystal and the increasing of TiO2 photoactivity. Diffractogram X-Ray of the samples showed that the synthesized TiO2 at 400 °C has been produced 100% TiO2 anatase. Synthesis of TiO2 doped Cr3+ composite was using wet impregnation method. The TiO2 doped Cr3+ composites have beed grown by annealed at a temperature of 300, 400, 500, 600 and 700 °C, respectively Annealing process have capabled to gain to the TiO2 doped Cr3+ nanocomposite. The result product annealed at 500 °C only appear anatase phase due to the Cr3+ addition influence that was able to suppress the growth of rutile. Identification of TiO2 doped Cr3+ composite using Fourier Transform Infra-Red (FT-IR) showed O-Cr vibration at 2283.72 cm-1. The TiO2 doped Cr3+ photoactivity was studied to degrade Rhodamin B. The best result on photodegradation of Rhodamin B was performed by using TiO2 doped Cr3+ composite which was annealed at 700 °C i.e. 74.71%.

  20. 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

  1. Adhesive and tribocorrosive behavior of TiAlPtN/TiAlN/TiAl multilayers sputtered coatings over CoCrMo

    NASA Astrophysics Data System (ADS)

    Canto, C. E.; Andrade, E.; Rocha, M. F.; Alemón, B.; Flores, M.

    2017-09-01

    The tribocorrosion resistance and adherence of multilayer coatings of TiAlPtN/TiAlN/TiAl synthesized by PVD reactive magnetron sputtering over a CoCrMo alloy substrate in 10 periods of 30 min each were analyzed and compared to those of the substrate alone and to that of a TiAlPtN single layer coating of the same thickness. The objective of the present work was to create multilayers with different amounts of Pt in order to enhance the tribocorrosion resistance of a biomedical alloy of CoCrMo. Tribocorrosion tests were performed using Simulated Body Fluid (SBF) at typical body temperature with a tribometer in a pin on disk test. The elemental composition and thickness of the coating which behave better at the tribocorrosion tests were evaluated by means of RBS (Rutherford Backscattering Spectroscopy) IBA (Ion Beam Analysis) technique, using an alpha particles beam of 1.8 MeV, before and after the reciprocating motion in the tribocorrosion test. In order to simulate the elemental profile of the samples, the SIMNRA simulation computer code was used. Measurements of the adhesion of the coatings to the substrate were carried on by means of a scratch test using a tribometer. By taking micrographs of the produced tracks, the critical loads at which the coatings are fully separated from the substrate were determined. From these tests it was observed that a coating with 10 min of TiAlPtN in a TiAlPtN/TiAl period of 30 min in multilayers of 10 periods and with an average thickness of 145 nm for the TiAlPtN nanolayers had the best tribocorrosion resistance behavior, compared to that of the CoCrMo alloy. The RBS experiments showed a reduction of the thickness of the films along with some loss of the multilayer structure after the reciprocating motion. The adhesion tests indicated that the multilayer with the average TiAlPtN thickness of 145 nm displayed the highest critical load. These results indicate a high correlation between the adherence and the tribocorrosion behavior.

  2. Synthesis of Ti Oxides at Reducing Conditions: Implications for Beamline Standards and Cosmochemistry

    NASA Technical Reports Server (NTRS)

    Righter, K.; Pando, K. A.; Butterworth, A. L.; Gainsforth, Z.; Jilly-Rehak, C. E.; Westphal, A. J.

    2017-01-01

    These initial experiments demonstrate the great potential for synthesizing customized compounds for use as standards, or in buffering experiments at reducing conditions. We are also investigating Cr and V oxides, as well as compounds containing these elements such as FeV2O4 and FeCr2O4. Oxygen fugacity exerts a major control on mineral major element chemistry and elemental valence of minerals in any plane-tary compositional system [1]. For Earth, Fe is multivalent ranging from nearly Fe0 at low fO2 in the deep mantle to Fe2+ to Fe3+ at high low fO2. For solar nebular and meteoritic materials fO2 ranges from near IW to 10 log fO2 units below the IW buffer [1]. Phases in CAIs, for example, contain no Fe2+, but may contain Ti4+, Ti3+, or Ti2+, and Cr3+ or Cr2+, and V3+ or V2+ [1,2,3]. De-tailed study of inclusions may reveal important differences in fO2 thus reflecting different environments in the solar nebula [4]. XANES, FEG-SEM, and TEM can reveal such variations in micro and nano samples such as Stardust and cosmic dust particles [5], but successful application to reduced conditions depends upon the availability of well characterized standards. Acquiring appropriate standards for reduced phases that contain Ti3+ or Ti2+, Cr3+ or Cr2+, and V3+ or V2+ can be a challenge. Here we report our preliminary results at synthesizing reduced Ti bearing standards, and focus on the preliminary characterization.

  3. Negative voltage modulated multi-level resistive switching by using a Cr/BaTiOx/TiN structure and quantum conductance through evidence of H2O2 sensing mechanism.

    PubMed

    Chakrabarti, Somsubhra; Ginnaram, Sreekanth; Jana, Surajit; Wu, Zong-Yi; Singh, Kanishk; Roy, Anisha; Kumar, Pankaj; Maikap, Siddheswar; Qiu, Jian-Tai; Cheng, Hsin-Ming; Tsai, Ling-Na; Chang, Ya-Ling; Mahapatra, Rajat; Yang, Jer-Ren

    2017-07-05

    Negative voltage modulated multi-level resistive switching with quantum conductance during staircase-type RESET and its transport characteristics in Cr/BaTiO x /TiN structure have been investigated for the first time. The as-deposited amorphous BaTiO x film has been confirmed by high-resolution transmission electron microscopy. X-ray photo-electron spectroscopy shows different oxidation states of Ba in the switching material, which is responsible for tunable more than 10 resistance states by varying negative stop voltage owing to slow decay value of RESET slope (217.39 mV/decade). Quantum conductance phenomenon has been observed in staircase RESET cycle of the memory devices. By inspecting the oxidation states of Ba + and Ba 2+ through measuring H 2 O 2 with a low concentration of 1 nM in electrolyte/BaTiO x /SiO 2 /p-Si structure, the switching mechanism of each HRS level as well as the multi-level phenomenon has been explained by gradual dissolution of oxygen vacancy filament. Along with negative stop voltage modulated multi-level, current compliance dependent multi-level has also been demonstrated and resistance ratio up to 2000 has been achieved even for a thin (<5 nm) switching material. By considering oxidation-reduction of the conducting filaments, the current-voltage switching curve has been simulated as well. Hence, multi-level resistive switching of Cr/BaTiO x /TiN structure implies the promising applications in high dense, multistate non-volatile memories in near future.

  4. Monte Carlo and Ab-initio calculation of TM (Ti, V, Cr, Mn, Fe, Co, Ni) doped MgH2 hydride: GGA and SIC approximation

    NASA Astrophysics Data System (ADS)

    Salmani, E.; Laghrissi, A.; Laamouri, R.; Benchafia, E.; Ez-Zahraouy, H.; Benyoussef, A.

    2017-02-01

    MgH2: TM (TM: V, Cr, Mn, Fe, Co, Ni) based dilute magnetic semiconductors (DMS) are investigated using first principle calculations. Our results show that the ferromagnetic state is stable when TM introduces magnetic moments as well as intrinsic carriers in TM: Co, V, Cr, Ti; Mg0.95TM0.05H2. Some of the DMS Ferro magnets under study exhibit a half-metallic behavior, which make them suitable for spintronic applications. The double exchange is shown to be the underlying mechanism responsible for the magnetism of such materials. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with Curie temperatures within the ambient conditions.

  5. Orthopyroxenes as Recorders of Diogenite Petrogenesis: Al-Cr-Ti Systematics

    NASA Astrophysics Data System (ADS)

    Fowler, G. W.; Papike, J. J.; Spilde, M. N.; Shearer, C. K.

    1993-07-01

    This research represents a continuing effort to understand the petrogenesis of diogenites and their relationship to eucrites. Our present suite of 17 diogenites includes: Aioun El Atrouss, Ellemeet, Garland, Ibbenburen, Johnstown, Manegoan, Peckelsheim, Roda, Shalka, Tatahouine, EET 83246, EET 83247, EET 87530, EET A79002, LEW 88008, and olivine diogenites ALH 84001 and ALH A77256. In our previous studies [1,2], we reported major, minor, and trace element systematics for a subgroup of 13 of these samples. In these studies, we concluded that Fe/Mg was compromised by post-crystallization annealing reactions. We also demonstrated [1] strong, positive correlations between Cr and Al along several trajectories on a Cr-Al data display. REE and Zr-Ti systematics indicate that most sampled diogenites represent cumulates from similar basaltic melts. These modeled melt compositions are similar to eucrites but show a greater compositional range. Here we further explore the Al-Cr-Ti systematics. Figure 1 (figures include over 1,000 high quality EMP analyses) is a Ti-Al plot that shows a main trend with a positive correlation between Ti and Al. Rhoda and one of the assemblages in polymict Garland have elevated Ti concentrations relative to the main trend while Manegoan has relatively depleted Ti concentrations. Figure 2 is a (Cr+Ti) vs. Al plot with a main trend that shows a strong, positive correlation between (Cr+Ti) and Al. Manegoan occupies the high (Cr+Ti)-Al end of the trend while Peckelsheim occupies the low end. Olivine diogenite ALH A77256 falls distinctly off the trend. However, ALH 84001, our only other olivine diogenite, plots with the other diogenite in the main trend. Several things are indicated by these systematics. The positive correlation of (Cr+Ti) vs. Al indicate that the most important charge balance couples are ^VITi^4+-^IVAl(sub)2, ^VITi^3+-^IVAl, ^VICr^3+-^IVAl, and ^VIAl-^IVAl. The ^VIAl-^IVAl couple is relatively more important in olivine diogenite ALH

  6. Preparation and Characterization of Ferroelectric BaTi0.91(Hf0.5, Zr0.5)0.09O3 Thin Films by Sol-Gel Process Using Titanium and Zirconium Alkoxides

    NASA Astrophysics Data System (ADS)

    Thongrueng, Jirawat; Nishio, Keishi; Nagata, Kunihiro; Tsuchiya, Toshio

    2000-09-01

    Sol-gel-derived BaTi0.91(Hf0.5, Zr0.5)0.09O3 (BTHZ-9) thin films have been successfully prepared on Pt and Pt(111)/Ti/SiO2/Si(100) substrates by spin-coating and sintering from 550 to 900°C for 2 h in oxygen ambient. X-ray diffraction measurement indicated that the single perovskite phase of the BTHZ-9 thin films was obtained at heat treatment above 650°C. The formation temperature of the double-alkoxy-derived BTHZ-9 thin films was lower by at least 80°C than that of the films prepared from only titanium alkoxide. The microstructure of the films was observed by atomic force microscopy and scanning electron microscopy. The grain size of the films increased from 70 to 200 nm with increasing sintering temperature ranging from 650 to 850°C. The maximum peak for the dielectric constant, corresponding to the Curie point (87°C), was broad and lower in magnitude compared with that of the BTHZ-9 bulk ceramics. Tensile stresses resulting from the differences between thermal expansion coefficients of the substrate and the film caused poor electrical properties. BTHZ-9 thin films exhibited a well-saturated polarization-electric field hysteresis loop. The polarization and coercive field for the 850-nm-thick BTHZ-9 thin film prepared on Pt/Ti/SiO2/Si substrate at 750°C were determined to be 8 μC/cm2 and 15 kV/cm, respectively. Those of the BTHZ-9 thin film prepared on Pt substrate at 850°C were found to be 9 μC/cm2 and 18 kV/cm, respectively.

  7. The permeation behavior of deuterium through 1Cr18Ni9Ti stainless steel with TiN+TiC-TiN multiple films

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

    Xiong, Y.; Song, J.; Luo, D.

    The prevention of tritium losses via permeation through structure components is an important issue in fusion technology. The production of thin layers on materials with low diffusivity and/or low surface recombination constants (so-called permeation barriers) seems to be the most practical method to reduce or hinder the permeation of tritium through materials. TiN+TiC+TiN multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel by ion-beam assisted deposition technology. The characteristics of films are tested by XPS ASEM and XRD, which shows that the film are compact and uniform with a thickness of about 15 μm, and have a goodmore » adherence with the substrate below 773 K. The diffraction peaks in the XRD patterns for TiC and TiN are broadened, implying that the multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel. Meanwhile, the C-H bonded CH{sub 4}-appears in the infrared spectra of multiple films, suggesting that the CH{sub 4}- is in a static state, so hydrogen atom cannot migrate from the site bonded with carbon to a neighboring site. The measured deuterium permeability in 1Cr18Ni9Ti stainless steel coated with multiple films is 2-3 orders of magnitude lower than that of pure 1Cr18Ni9Ti stainless steel substrate from 473 K to 773 K. However, this barrier is partly destroyed above 773 K.« less

  8. 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

  9. High-level ab initio predictions for the ionization energy, electron affinity, and heats of formation of cyclopentadienyl radical, cation, and anion, C5H5/C5H5+/C5H5-.

    PubMed

    Lo, Po-Kam; Lau, Kai-Chung

    2014-04-03

    The ionization energy (IE), electron affinity (EA), and heats of formation (ΔH°f0/ΔH°f298) for cyclopentadienyl radical, cation, and anion, C5H5/C5H5(+)/C5H5(-), have been calculated by wave function-based ab initio CCSDT/CBS approach, which involves approximation to complete basis set (CBS) limit at coupled-cluster level with up to full triple excitations (CCSDT). The zero-point vibrational energy correction, core-valence electronic correction, scalar relativistic effect, and higher-order corrections beyond the CCSD(T) wave function are included in these calculations. The allylic [C5H5((2)A2)] and dienylic [C5H5((2)B1)] forms of cyclopentadienyl radical are considered: the ground state structure exists in the dienyl form and it is about 30 meV more stable than the allylic structure. Both structures are lying closely and are interconvertible along the normal mode of b2 in-plane vibration. The CCSDT/CBS predictions (in eV) for IE[C5H5(+)((3)A1')←C5H5((2)B1)] = 8.443, IE[C5H5(+)((1)A1)←C5H5((2)B1)] = 8.634 and EA[C5H5(-)((1)A1')←C5H5((2)B1)] = 1.785 are consistent with the respective experimental values of 8.4268 ± 0.0005, 8.6170 ± 0.0005, and 1.808 ± 0.006, obtained from photoelectron spectroscopic measurements. The ΔH°f0/ΔH°f298's (in kJ/mol) for C5H5/C5H5(+)/C5H5(-) have also been predicted by the CCSDT/CBS method: ΔH°f0/ΔH°f298[C5H5((2)B1)] = 283.6/272.0, ΔH°f0/ΔH°f298[C5H5(+)((3)A1')] = 1098.2/1086.9, ΔH°f0/ΔH°f298[C5H5(+)((1)A1)] = 1116.6/1106.0, and ΔH°f0/ΔH°f298[C5H5(-)((1)A1')] = 111.4/100.0. The comparisons between the CCSDT/CBS predictions and the experimental values suggest that the CCSDT/CBS procedure is capable of predicting reliable IE(C5H5)'s and EA(C5H5) with uncertainties of ± 17 and ± 23 meV, respectively.

  10. Room-temperature ferromagnetism in Fe-based perovskite solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials

    NASA Astrophysics Data System (ADS)

    Hung, Nguyen The; Bac, Luong Huu; Trung, Nguyen Ngoc; Hoang, Nguyen The; Van Vinh, Pham; Dung, Dang Duc

    2018-04-01

    The integration of ferromagnetism in lead-free ferroelectric materials is important to fabricate smart materials for electronic devices. In this work, (1 - x)Bi0.5Na0.5TiO3 + xMgFeO3-δ materials (x = 0-9 mol%) were prepared through sol-gel method. X-ray diffraction characterization indicated that MgFeO3-δ materials existed as a well solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials. The rhombohedral structure of Bi0.5Na0.5TiO3 materials was distorted due to the random distribution of Mg and Fe cations into the host lattice. The reduced optical band gap and the induced room-temperature ferromagnetism were due to the spin splitting of transition metal substitution at the B-site of perovskite Bi0.5Na0.5TiO3 and the modification by A-site co-substitution. This work elucidates the role of secondary phase as solid solution in Bi0.5Na0.5TiO3 material for development of lead-free multiferroelectric materials.

  11. Effect of Quenching Process on Microstructures and Mechanical Properties of Fe-0.9Mn-0.5Cr-2.4Ni-0.5Mo-C Steel

    NASA Astrophysics Data System (ADS)

    Chen, Jie; Li, Changsheng; Jin, Xin; Chen, Liqing; Fang, Lei

    2018-03-01

    To develop an appropriate quenching process to produce Fe-0.9Mn-0.5Cr-2.4Ni-0.5Mo-C steel, the microstructures and mechanical properties of this steel were investigated under the direct quenching and tempering (DQT) and the direct quenching, reheated quenching and tempering (DQQT) heat treatment processes. The microstructure of the DQQT specimen was basically tempered sorbite with spherical precipitates, while quite a bit of tempered martensite was in the DQT specimen with dispersive nanoscaled precipitates. The yield strengths of the DQT and DQQT specimens were 1154 and 955 MPa, respectively. The yield strength of the DQT specimen was higher than that of the DQQT specimen because of its finer grain size, higher density of dislocations and dispersed precipitates. The DQQT specimen had spherical precipitates, which hindered the propagation of the crack. Moreover, the high-angle grain boundaries in the DQQT specimen took a higher proportion. Therefore, the Charpy impact values of DQT and DQQT specimens at - 60 °C were 38 and 75 J, respectively. Consequently, the mechanical properties of the Fe-0.9Mn-0.5Cr-2.4Ni-0.5Mo-C steel, which met the standard of 1000 MPa grade steel plate for hydropower station, were acquired by the DQQT process.

  12. Improved Cr II log(gf)s and Cr Abundances in the Photospheres of the Sun and Metal-Poor Star HD 84937

    NASA Astrophysics Data System (ADS)

    Lawler, James E.; Sneden, Chris; Nave, Gillian; Den Hartog, Elizabeth; Emrahoglu, Nuri; Cowan, John J.

    2017-01-01

    New laser induced fluorescence (LIF) data for eight levels of singly ionized chromium (Cr) and emission branching fraction (BF) measurements for 183 lines of the second spectrum of chromium (Cr II) are reported. A goal of this study is to reconcile Solar and stellar Cr abundance values based on Cr I and Cr II lines. Analyses of eighteen spectra from three Fourier Transform Spectrometers supplemented with ultraviolet spectra from a high resolution echelle spectrometer yield the BF measurements. Radiative lifetimes from LIF measurements are used to convert the BFs to absolute transition probabilities. These new laboratory data are applied to determine the Cr abundance log eps in the Sun and metal-poor star HD 84937. The mean result in the Sun is Cr II)> = 5.624 ± 0.009 compared to Cr I)> = 5.644 ± 0.006 on a scale with the H abundance log eps(H) = 12. Similarily the photosphere of HD 84937 is found to be in Saha balance with Cr II)> = 3.417 ± 0.006 and Cr I, E.P. > 0 eV) > = 3.374 ± 0.011 for this dwarf star. The resonance (E.P. = 0 eV) lines of Cr I reveal overionization of the ground level of neutral Cr. We find a correlation of Cr with the iron-peak element Ti, suggesting an associated or related nucleosynthetic production. Four iron-peak elements (Cr along with Ti, V and Sc) appear to have a similar (or correlated) production history - other iron-peak elements appear not to be associated with Cr.This work is supported in part by NASA grant NNX16AE96G (J.E.L.), by NSF grant AST-1516182 (J.E.L. & E.D.H.), by NASA interagency agreement NNH10AN381 (G.N.), and NSF grant AST-1211585 (C.S.). Postdoctoral research support for N. E. is from the Technological and Scientific Research Council of Turkey (TUBITAK).

  13. Process for producing Ti-Cr-Al-O thin film resistors

    DOEpatents

    Jankowski, Alan F.; Schmid, Anthony P.

    2001-01-01

    Thin films of Ti-Cr-Al-O are used as a resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O.sub.2. Resistivity values from 10.sup.4 to 10.sup.10 Ohm-cm have been measured for Ti-Cr-Al-O film <1 .mu.m thick. The film resistivity can be discretely selected through control of the target composition and the deposition parameters. The application of Ti-Cr-Al-O as a thin film resistor has been found to be thermodynamically stable, unlike other metal-oxide films. The Ti-Cr-Al-O film can be used as a vertical or lateral resistor, for example, as a layer beneath a field emission cathode in a flat panel display; or used to control surface emissivity, for example, as a coating on an insulating material such as vertical wall supports in flat panel displays.

  14. Flat panel display using Ti-Cr-Al-O thin film

    DOEpatents

    Jankowski, Alan F.; Schmid, Anthony P.

    2002-01-01

    Thin films of Ti--Cr--Al--O are used as a resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O.sub.2. Resistivity values from 10.sup.4 to 10.sup.10 Ohm-cm have been measured for Ti--Cr--Al--O film <1 .mu.m thick. The film resistivity can be discretely selected through control of the target composition and the deposition parameters. The application of Ti--Cr--Al--O as a thin film resistor has been found to be thermodynamically stable, unlike other metal-oxide films. The Ti--Cr--Al--O film can be used as a vertical or lateral resistor, for example, as a layer beneath a field emission cathode in a flat panel display; or used to control surface emissivity, for example, as a coating on an insulating material such as vertical wall supports in flat panel displays.

  15. In-depth evolution of chemical states and sub-10-nm-resolution crystal orientation mapping of nanograins in Ti(5 nm)/Au(20 nm)/Cr(3 nm) tri-layer thin films

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoli; Todeschini, Matteo; Bastos da Silva Fanta, Alice; Liu, Lintao; Jensen, Flemming; Hübner, Jörg; Jansen, Henri; Han, Anpan; Shi, Peixiong; Ming, Anjie; Xie, Changqing

    2018-09-01

    The applications of Au thin films and their adhesion layers often suffer from a lack of sufficient information about the chemical states of adhesion layers and about the high-lateral-resolution crystallographic morphology of Au nanograins. Here, we demonstrate the in-depth evolution of the chemical states of adhesive layers at the interfaces and the crystal orientation mapping of gold nanograins with a lateral resolution of less than 10 nm in a Ti/Au/Cr tri-layer thin film system. Using transmission electron microscopy, the variation in the interdiffusion at Cr/Au and Ti/Au interfaces was confirmed. From X-ray photoelectron spectroscopy (XPS) depth profiling, the chemical states of Cr, Au and Ti were characterized layer by layer, suggesting the insufficient oxidation of the adhesive layers. At the interfaces the Au 4f peaks shift to higher binding energies and this behavior can be described by a proposed model based on electron reorganization and substrate-induced final-state neutralization in small Au clusters supported by the partially oxidized Ti layer. Utilizing transmission Kikuchi diffraction (TKD) in a scanning electron microscope, the crystal orientation of Au nanograins between two adhesion layers was non-destructively characterized with sub-10 nm spatial resolution. The results provide nanoscale insights into the Ti/Au/Cr thin film system and contribute to our understanding of its behavior in nano-optic and nano-electronic devices.

  16. 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.

  17. Electrochemical oxidation of 2,4,5-trichlorophenoxyacetic acid by metal-oxide-coated Ti electrodes.

    PubMed

    Maharana, Dusmant; Xu, Zesheng; Niu, Junfeng; Rao, Neti Nageswara

    2015-10-01

    Electrochemical oxidation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) over metal-oxide-coated Ti anodes, i.e., Ti/SnO2-Sb/Ce-PbO2, Ti/SnO2-Sb and Ti/RuO2, was examined. The degradation efficiency of over 90% was attained at 20 min at different initial concentrations (0.5-20 mg L(-1)) and initial pH values (3.1-11.2). The degradation efficiencies of 2,4,5-T on Ti/SnO2-Sb/Ce-PbO2, Ti/SnO2-Sb and Ti/RuO2 anodes were higher than 99.9%, 97.2% and 91.5% at 30 min, respectively, and the respective total organic carbon removal ratios were 65.7%, 54.6% and 37.2%. The electrochemical degradation of 2,4,5-T in aqueous solution followed pseudo-first-order kinetics. The compounds, i.e., 2,5-dichlorohydroquinone and 2,5-dihydroxy-p-benzoquinone, have been identified as the main aromatic intermediates by liquid chromatography-mass spectrometry. The results showed that the energy efficiencies of 2,4,5-T (20 mg L(-1)) degradation with Ti/SnO2-Sb/Ce-PbO2 anode at the optimal current densities from 2 to 16 mA cm(-2) ranged from 8.21 to 18.73 kWh m(-3). Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Dielectric and AC conductivity studies of Nd substituted 0.8BaTiO{sub 3}-0.2(Bi{sub 0.5(1-x)}Nd{sub 0.5x}K{sub 0.5})TiO{sub 3} lead free ceramics

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

    Ramesh, M. N. V.; Ramesh, K. V., E-mail: kv-ramesh5@yahoo.co.in

    2016-05-23

    0.8BaTiO{sub 3} – 0.2(Bi{sub 0.5(1-x)}Nd{sub 0.5x}K{sub 0.5})TiO{sub 3} (0.01 ≤ x ≤ 0.06) lead free ceramic materials have been prepared by solid state reaction method and followed by high energy ball milling process. X-ray diffraction studies confirm the tetragonal structure of the materials at room temperature. Lattice parameters and density are decreasing with increase of Nd substitution. Microstructure studies were done by using Scanning electron microscope and it found that grain size is decreasing with increase of Nd substitution. Temperature and frequency dependent dielectric studies reveal relaxor behaviour of the materials. Dielectric constant, dielectric loss and Curie temperature are decreasingmore » with Nd substitution. Maximum Curie temperature of 195°C was observed at 1 MHz for x=0.01 Nd substituted sample. Degree of diffuseness was calculated from the modified Curie-Weiss law and it is increasing with Nd substitution. AC conductivity is increasing with increase of Nd substitution and observed maximum activation energy of 0.52 eV for x=0.02 Nd substituted sample.« less

  19. Possible ferrimagnetism and ferroelectricity of half-substituted rare-earth titanate: A first-principles study on Y0.5La0.5TiO3

    NASA Astrophysics Data System (ADS)

    An, Ming; Zhang, Hui-Min; Weng, Ya-Kui; Zhang, Yang; Dong, Shuai

    2016-04-01

    Titanates with the perovskite structure, including ferroelectrics (e.g., BaTiO3) and ferromagnetic ones (e.g., YTiO3), are important functional materials. Recent theoretical studies predicted multiferroic states in strained EuTiO3 and titanate superlattices, the former of which has already been experimental confirmed. Here, a first-principles calculation is performed to investigate the structural, magnetic, and electronic properties of Y half-substituted LaTiO3. Our results reveal that the magnetism of Y0.5La0.5TiO3 sensitively depends on its structural details because of the inherent phase competition. The lowest energy state is the ferromagnetic state, resulting in 0.25 μ B /Ti. Furthermore, some configurations of Y0.5La0.5TiO3 exhibit hybrid improper polarizations, which can be significantly affected by magnetism, resulting in the multiferroic properties. Because of the quenching disorder of substitution, the real Y0.5La0.5TiO3 material with random A-site ions may exhibit interesting relaxor behaviors.

  20. Chemical and electrochemical behavior of the Cr(3)/Cr(2) half cell in the NASA Redox Energy Storage System

    NASA Technical Reports Server (NTRS)

    Johnson, D. A.; Reid, M. A.

    1982-01-01

    The Cr(III) complexes in the NASA Redox Energy Storage System were isolated and identified as Cr(H2O)6(+3) and Cr(H2O)5Cl(+2) by ion exchange chromatography and visible spectrophotometry. The cell reactions during charge-discharge cycles were followed by means of visible spectrophotometry. The spectral bands were resolved into component peaks and concentrations calculated using Beer's Law. During the charge mode Cr(H2O)5Cl(+2) is reduced to Cr(H2O)5Cl(+) and during the discharge mode Cr(H2O)5Cl(+) is oxidized back to Cr(H2O)5Cl(+2). Both electrode reactions occur via a chloride-bridge inner-sphere reaction pathway. Hysteresis effects can be explained by the slow attainment of equilibrium between Cr(H2O)6(+3) and Cr(H2O)5Cl(+2).

  1. Effects of combined plasma chromizing and shot peening on the fatigue properties of a Ti6Al4V alloy

    NASA Astrophysics Data System (ADS)

    Yu, Shouming; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing

    2015-10-01

    A plasma chromizing treatment was conducted on Ti6Al4V samples by employing the recently developed double glow plasma surface alloying technology. The Cr-alloyed layer consisted of four sub-layers, namely the Cr deposition, Cr2Ti, CrTi4, and Cr-Ti solid-solution layers. The local hardness and moduli were determined via nanoindentation. In addition, the fatigue properties of the samples were evaluated by using a rotating-bending fatigue machine under a given load. The results showed that the hardness or elastic moduli of the adjacent sub-layers differed significantly and the fatigue properties of the Ti6Al4V alloy deteriorated with the plasma chromizing treatment. This deterioration stemmed mainly from cracks initiated at the interfaces between the sub-layers and the microstructural changes of the substrate; these changes were induced by the high temperature used in the plasma chromizing process. However, the fatigue life of the plasma-chromized samples was increased by a shot peening post-treatment. The fatigue life of the samples resulting from this combination of treatments was slightly higher than that of the single-shot-peened Ti6Al4V substrate. In fact, the sample retaining only the Cr-Ti solid-solution layer (that is, the first three sub-layers were removed), when shot-peened, exhibited the highest fatigue life among all the tested samples; this was attributed to that sample having the highest residual compressive stress, the significant work hardening, and the good hardness to toughness balance.

  2. Structural and dielectric characteristics of Ba3Ln3Ti5Nb5O30 (Ln = La, Nd, Sm) filled tungsten bronze ceramics

    NASA Astrophysics Data System (ADS)

    Chen, Wang; Gao, Ting Ting; Zhu, Xiao Li; Chen, Xiang Ming

    2018-03-01

    In the present work, the structural, dielectric and relaxor ferroelectric properties were investigated for Ba3Ln3Ti5Nb5O30 (Ln = La, Nd, Sm) ceramics. The filled tungsten bronze phase with space group P4/mbm was confirmed for all compositions, while a small amount of secondary phase was detected in Ba3Nd3Ti5Nb5O30 and Ba3Sm3Ti5Nb5O30. The typical relaxor ferroelectric behaviors were observed: a broad peak of dielectric constant shifting to higher temperatures and decreasing its magnitude with increasing frequency and the frequency dispersion obeying the Vogel-Fulcher relationship. The P-E (polarization-electric field) hysteresis loops were obtained for Ba3Ln3Ti5Nb5O30 (Ln = La, Nd, Sm) ceramics at low temperatures. The nanoscale ferroelectric 180° domains with strip-like shape were observed in the paraelectric matrix at room temperature, where the commensurate structural modulations were determined in the domains and incommensurate ones were determined in the matrix. The significant differences were determined between the present ceramics and Ba4Ln2Ti4Nb6O30 and Ba5LnTi3Nb7O30 because of the different distribution patterns of A1 and A2 cations.

  3. Enhanced tunability of magnetron sputtered Ba0.5Sr0.5TiO3 thin films on c-plane sapphire substrates

    NASA Astrophysics Data System (ADS)

    Fardin, E. A.; Holland, A. S.; Ghorbani, K.; Reichart, P.

    2006-07-01

    Thin films of Ba0.5Sr0.5TiO3 (BST) were deposited on c-plane (0001) sapphire by rf magnetron sputtering and investigated by complementary materials analysis methods. Microwave properties of the films, including tunability and Q factor were measured from 1to20GHz by patterning interdigital capacitors (IDCs) on the film surface. The tunability is correlated with texture, strain, and grain size in the deposited films. An enhanced capacitance tunability of 56% at a bias field of 200kV/cm and total device Q of more than 15 (up to 20GHz) were achieved following postdeposition annealing at 900°C.

  4. Alloy Design and Development of Cast Cr-W-V Ferritic Steels for Improved High-Temperature Strength for Power Generation Applications

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

    Klueh, R L; Maziasz, P J; Vitek, J M

    2006-09-23

    Economic and environmental concerns demand that the power-generation industry seek increased efficiency for gas turbines. Higher efficiency requires higher operating temperatures, with the objective temperature for the hottest sections of new systems {approx} 593 C, and increasing to {approx} 650 C. Because of their good thermal properties, Cr-Mo-V cast ferritic steels are currently used for components such as rotors, casings, pipes, etc., but new steels are required for the new operating conditions. The Oak Ridge National Laboratory (ORNL) has developed new wrought Cr-W-V steels with 3-9% Cr, 2-3% W, 0.25% V (compositions are in wt.%), and minor amounts of additionalmore » elements. These steels have the strength and toughness required for turbine applications. Since cast alloys are expected to behave differently from wrought material, work was pursued to develop new cast steels based on the ORNL wrought compositions. Nine casting test blocks with 3, 9, and 11% Cr were obtained. Eight were Cr-W-V-Ta-type steels based on the ORNL wrought steels; the ninth was COST CB2, a 9Cr-Mo-Co-V-Nb cast steel, which was the most promising cast steel developed in a European alloy-development program. The COST CB2 was used as a control to which the new compositions were compared, and this also provided a comparison between Cr-W-V-Ta and Cr-Mo-V-Nb compositions. Heat treatment studies were carried out on the nine castings to determine normalizing-and-tempering treatments. Microstructures were characterized by both optical and transmission electron microscopy (TEM). Tensile, impact, and creep tests were conducted. Test results on the first nine cast steel compositions indicated that properties of the 9Cr-Mo-Co-V-Nb composition of COST CB2 were better than those of the 3Cr-, 9Cr-, and 11Cr-W-V-Ta steels. Analysis of the results of this first iteration using computational thermodynamics raised the question of the effectiveness in cast steels of the Cr-W-V-Ta combination versus the

  5. Composition design for Laves phase-related body-centered cubic-V solid solution alloys with large hydrogen storage capacities.

    PubMed

    Wang, H B; Wang, Q; Dong, C; Yuan, L; Xu, F; Sun, L X

    2008-03-19

    This paper analyzes the characteristics of alloy compositions with large hydrogen storage capacities in Laves phase-related body-centered cubic (bcc) solid solution alloy systems using the cluster line approach. Since a dense-packed icosahedral cluster A(6)B(7) characterizes the local structure of AB(2) Laves phases, in an A-B-C ternary system, such as Ti-Cr (Mn, Fe)-V, where A-B forms AB(2) Laves phases while A-C and B-C tend to form solid solutions, a cluster line A(6)B(7)-C is constructed by linking A(6)B(7) to C. The alloy compositions with large hydrogen storage capacities are generally located near this line and are approximately expressed with the cluster-plus-glue-atom model. The cluster line alloys (Ti(6)Cr(7))(100-x)V(x) (x = 2.5-70 at.%) exhibit different structures and hence different hydrogen storage capacities with increasing V content. The alloys (Ti(6)Cr(7))(95)V(5) and Ti(30)Cr(40)V(30) with bcc solid solution structure satisfy the cluster-plus-glue-atom model.

  6. Exposure to PM2.5 in modern office buildings through elemental characterization and oxidative potential

    NASA Astrophysics Data System (ADS)

    Szigeti, Tamás; Kertész, Zsófia; Dunster, Christina; Kelly, Frank J.; Záray, Gyula; Mihucz, Victor G.

    2014-09-01

    Fifty samples of indoor and outdoor PM2.5 were collected onto quartz fiber and Teflon membrane filters in five office buildings equipped with heating, ventilation and air-conditioning system for 8 h daily in order to coincide with the work shift of employees. Samples were analyzed for i) mass concentration; ii) elemental concentration; and iii) oxidative potential (OP) through antioxidant depletion. The PM2.5 mass concentration exceeded the annual mean guideline of 10 μg m-3 WHO in 50% of the samples. Indoor and outdoor PM2.5 mass concentrations correlated almost linearly. Proton-induced X-ray emission (PIXE) spectrometry was used for the monitoring of 21 elements. Quantitative determination was achieved in the case of Teflon filters only for Al, Si, S, Cl, K, Ca, Ti, Cr, Mn, Fe and Zn at ng m-3 concentration level. Quartz fiber filters were less adequate for the PIXE measurements due to their greater thickness and filamentary structure. Ca, Cr, Zn and Ti had generally higher concentration (mg g-1) indoors. Indoor/outdoor (I/O) OP values were higher than one in 14% and 57% of the samples in the case of ascorbate and reduced glutathione (GSH), respectively. Spatial and temporal variations of OP were observed across the office buildings. The I/O ratios for OP, Cr and Zn concentrations in the case of GSH were higher for three buildings. Significant relationship was observed between GSH oxidation and Cr and Zn concentrations. Thus, employees were exposed to a higher extent to reactive oxygen species in three buildings.

  7. Microstructure and wear resistance of laser cladded Ni-Cr-Co-Ti-V high-entropy alloy coating after laser remelting processing

    NASA Astrophysics Data System (ADS)

    Cai, Zhaobing; Cui, Xiufang; Liu, Zhe; Li, Yang; Dong, Meiling; Jin, Guo

    2018-02-01

    An attempt, combined with the technologies of laser cladding and laser remelting, has been made to develop a Ni-Cr-Co-Ti-V high entropy alloy coating. The phase composition, microstructure, micro-hardness and wear resistance (rolling friction) were studied in detail. The results show that after laser remelting, the phase composition remains unchanged, that is, as-cladded coating and as-remelted coatings are all composed of (Ni, Co)Ti2 intermetallic compound, Ti-rich phase and BCC solid solution phase. However, after laser remelting, the volume fraction of Ti-rich phase increases significantly. Moreover, the micro-hardness is increased, up to ∼900 HV at the laser remelting parameters: laser power of 1 kW, laser spot diameter of 3 mm, and laser speed of 10 mm/s. Compared to the as-cladded high-entropy alloy coating, the as-remelted high-entropy alloy coatings have high friction coefficient and low wear mass loss, indicating that the wear resistance of as-remelted coatings is improved and suggesting practical applications, like coatings on brake pads for wear protection. The worn surface morphologies show that the worn mechanism of as-cladded and as-remelted high-entropy alloy coatings are adhesive wear.

  8. Half-metallic magnetism in Ti 3Co 5-xFe xB 2

    DOE PAGES

    Pathak, Rohit; Ahamed, Imran; Zhang, W. Y.; ...

    2017-02-08

    Here, bulk alloys and thin films of Fe-substituted Ti 3Co 5B 2 have been investigated by first-principle density-functional calculations. The series, which is of interest in the context of alnico magnetism and spin electronics, has been experimentally realized in nanostructures but not in the bulk. Our bulk calculations predict paramagnetism for Ti 3Co 5B 2, Ti 3Co 4FeB 2 and Ti 3CoFe 4B 2, whereas Ti 3Fe 5B 2 is predicted to be ferromagnetic. The thin films are all ferromagnetic, indicating that moment formation may be facilitated at nanostructural grain boundaries. One member of the thin-film series, namely Ti 3CoFemore » 4B 2, is half-metallic and exhibits perpendicular easy-axis magnetic anisotropy. The half-metallicity reflects the hybridization of the Ti, Fe and Co 3d orbitals, which causes a band gap in minority spin channel, and the limited equilibrium solubility of Fe in bulk Ti 3Co 5B 2 may be linked to the emerging half-metallicity due to Fe substitution.« less

  9. Half-metallic magnetism in Ti 3Co 5-xFe xB 2

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

    Pathak, Rohit; Ahamed, Imran; Zhang, W. Y.

    Here, bulk alloys and thin films of Fe-substituted Ti 3Co 5B 2 have been investigated by first-principle density-functional calculations. The series, which is of interest in the context of alnico magnetism and spin electronics, has been experimentally realized in nanostructures but not in the bulk. Our bulk calculations predict paramagnetism for Ti 3Co 5B 2, Ti 3Co 4FeB 2 and Ti 3CoFe 4B 2, whereas Ti 3Fe 5B 2 is predicted to be ferromagnetic. The thin films are all ferromagnetic, indicating that moment formation may be facilitated at nanostructural grain boundaries. One member of the thin-film series, namely Ti 3CoFemore » 4B 2, is half-metallic and exhibits perpendicular easy-axis magnetic anisotropy. The half-metallicity reflects the hybridization of the Ti, Fe and Co 3d orbitals, which causes a band gap in minority spin channel, and the limited equilibrium solubility of Fe in bulk Ti 3Co 5B 2 may be linked to the emerging half-metallicity due to Fe substitution.« less

  10. Magnetic properties and thermal stability of Ti-doped CrO2 films

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Cheng, M.; Lu, Z.; Yu, Z.; Liu, S.; Liang, R.; Liu, Y.; Shi, J.; Xiong, R.

    2018-04-01

    Chromium dioxide (CrO2) is a striking half metal material which may have important applications in the field of spintronics. However, pure CrO2 film is metastable at room temperature and the synthesis process can be only performed in a narrow temperature range of 390-410 °C with TiO2 used as substrate material. Here, we report the preparation and investigation of (1 0 0) oriented Ti-doped CrO2 films on TiO2 substrates. It is found that Ti-doped films can maintain pure rutile phase even after a 510 °C post-annealing, showing much better thermal stability than pure CrO2 films. Ti-doped films can be prepared in a wider temperature window (390-470 °C), which may be attributed to the improvement of thermal stability. The broadening of process window may be beneficial for further improvement of film quality by optimizing growth temperature in a larger range. In addition to the improvement of thermal stability, the magnetic properties of Ti-doped CrO2 are also found to be tuned by Ti doping: saturation magnetizations of Ti-doped films at room temperature are significantly lower, and magnetic anisotropy decreases as the Ti-concentration increases, which is beneficial for decreasing switching current density in STT-based spintronic devices.

  11. Photocatalytic CO2 reduction by Cr-substituted Ba2(In2-xCrx)O5·(H2O)δ (0.04 ≤ x ≤ 0.60)

    NASA Astrophysics Data System (ADS)

    Yoon, Songhak; Gaul, Michael; Sharma, Sitansh; Son, Kwanghyo; Hagemann, Hans; Ziegenbalg, Dirk; Schwingenschlogl, Udo; Widenmeyer, Marc; Weidenkaff, Anke

    2018-04-01

    Cr-substituted polycrystalline Ba2(In2-xCrx)O5·(H2O)δ powders (0.04 ≤ x ≤ 0.60) were synthesized by solid state reaction to investigate the relation of crystal structure, thermochemical, magnetic, and optical properties. The Cr-substitution results in an unit cell expansion and formation of the higher-symmetric tetragonal phase together with increased oxygen and hydrogen contents. Magnetic property measurements reveal that the diamagnetic pristine Ba2In2O5·(H2O)δ becomes magnetically ordered upon Cr-substitution. By UV-vis spectroscopy a gradual shift of the absorption-edge energy to lower values was observed. Numerical calculations showed that the observed bandgap narrowing was ascribed to the Cr induced states near the Fermi level. The correlation between the changes of crystal chemistry, magnetic, and optical properties of Cr-substituted Ba2(In2-xCrx)O5·(H2O)δ can be explained by the replacement of In by Cr. Consequently, an enhanced photocatalytic CO2 reduction activity was observed with increasing Cr substitution, compatible with the state-of-the-art high surface area TiO2 photocatalyst (P-25).

  12. Electric Field-Induced Large Strain in Ni/Sb-co Doped (Bi0.5Na0.5) TiO3-Based Lead-Free Ceramics

    NASA Astrophysics Data System (ADS)

    Li, Liangliang; Hao, Jigong; Xu, Zhijun; Li, Wei; Chu, Ruiqing

    2018-02-01

    Lead-free piezoelectric ceramics (Bi0.5Na0.5)0.935Ba0.065Ti1- x (Ni0.5Sb0.5) x O3 (BNBT6.5- xNS) have been fabricated using conventional solid sintering technique. The effect of (Ni, Sb) doping on the phase structure and electrical properties of BNBT6.5 ceramics were systematically investigated. Results show that the addition of (Ni, Sb) destroyed the ferroelectric long-range order of BNBT6.5 and shifted the ferroelectric-relaxor transition temperature ( T F-R) down to room temperature. Thus, this process induced an ergodic relaxor phase at zero field in samples with x = 0.005. Under the electric field, the ergodic relaxor phase could reversibly transform to ferroelectric phase, which promotes the strain response with peak value of 0.38% (at 80 kV/cm, corresponding to d 33 * = 479 pm/V) at x = 0.005. Temperature-dependent measurements of both polarization and strain confirmed that the large strain originated from a reversible field-induced ergodic relaxor to ferroelectric phase transformation. The proposed material exhibits potential for nonlinear actuators.

  13. Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

    NASA Astrophysics Data System (ADS)

    Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

    2018-04-01

    Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

  14. Ordered bimetallic ferromagnets of chromium(III): [Cr(NH 3) 6][Cr(CN) 6], [Cr(H 2O)(NH 3) 5][Cr(CN) 6], and trans-[Cr(en) 2(H 2O) 2]trans-[Cr(en) 2(OH)F] 2(CIO 4) 5·2H 2O

    NASA Astrophysics Data System (ADS)

    Burriel, Ramón; Casabó, Jaime; Pons, Josefina; Carnegie, David W.; Carlin, Richard L.

    1985-07-01

    The magnetic bahavior of the isomorphous compounds [Cr(NH 3) 6][Cr(CN) 6] and [Cr(H 2O)(NH 3) 5][Cr(CN) 6] has been studied by means of zero-field susceptibility measurements. The materials order ferromagnetically at 0.60 and 0.38K, respectively. The compounds behave as examples of the ferromagnetic ( S=3/2) Heisenberg body-center-cubic lattice. The susceptibilities have been analyzed and compared to the Padé approximants of the high-temperature series expansion for this model, a remarkably good fit being obtained with exchange constants 0.042 and 0.022 K, respectively. Another bimetallic substance, trans-[Cr(en) 2(H 2O) 2] trans-[Cr(en) 2(OH)F] 2(CIO 4) 5·2H 2O, with a dominant Heisenberg ferromagnetic interaction J/ kB=0.122 K in one dimension, orders antiferromagnetically at 0.14 K due to a weaker interchain interaction with exchange constant z‧ J‧/ kB=-0.019 K. The three sets of measurements have been carried out on powdered samples for which demagnetization effects are important. The exchange interactions are remarkably weak for such concentrated magnetic materials, yet they are stronger than those found in a number of other such Cr/Cr compounds.

  15. The effect of sintering temperature on electrical characteristics of Fe2TiO5/Nb2O5 ceramics for NTC thermistor

    NASA Astrophysics Data System (ADS)

    Wiendartun, Risdiana, Fitrilawati, Siregar, R. E.

    2016-02-01

    A study on the fabrication of Iron Titanium Oxide (Fe2TiO5) ceramics for negative temperature coefficient (NTC) thermistors has been carried out, in order to know the effect of sintering temperature on the electrical characteristic of 1.0 % mole Nb2O5 doped Fe2TiO5 ceramics.These ceramics were made by mixing commercial powders of Fe2O3, TiO2 and Nb2O5 with proportional composition to produce Fe2TiO5 based ceramic. The raw pellet was sintered at 1000 °C, 1100 °C and 1200 °C temperature for 2 hours in air. Analysis of the microstructure and crystal structure were performed by using a scanning electron microscope (SEM) and x-ray diffraction (XRD) respectively. XRD spectra showed that the crystal structure of all ceramics of Fe2TiO5 made at various sintering temperatures are orthorhombic. The SEM images showed that the grain size of pellet ceramics increase with increasing sintering temperatures. From electrical resistances data that was measured at temperature 30-300 °C, it is found that the value of thermistor constant (B), activation energy (Ea), thermistor sensitivity (α) and room temperature resistance (RRT) decreases with respect to the increasing of sintering temperature. The fabricated Fe2TiO5 ceramics have thermistor constants (B = 6394-6959 K). This can be applied as temperature sensor, and will fulfill the market requirement.

  16. High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Ren, Weijun; Peng, Ping; Guo, Shaobo; Lu, Teng; Liu, Yun; Dong, Xianlin; Wang, Genshui

    2018-04-01

    Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ˜ 3.7 × 10-8 C cm-2 K-1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10-10 m/V, 2.89 × 10-2 m2/C, and 1.15 × 10-5 Pa-1/2 at 1 kHz and 1.32 × 10-10 m/V, 2.70 × 10-2 m2/C, and 1.09 × 10-5 Pa-1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ˜400 × 10-8 C cm-2 K-1 are suggested to be responsible for this thermal stability, which ensures reliable actual operation. The results reveal the BNT-BA-KNN ceramics as promising lead-free candidates for infrared thermal detector applications.

  17. Structural, thermal and electrical conductivity characteristics of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm) complex perovskites as anode materials for solid oxide fuel cell

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

    Jeong, Jihoon; Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712; Azad, Abul K.

    2015-03-15

    The Ti and Mn replaced complex perovskites, Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm), were reported as potential anode materials for high temperature-operating solid oxide fuel cells (HT-SOFCs). For the present research study, synthesis, crystallographic, thermal and electrical conductivity properties of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} complex perovskites were investigated using X-ray diffraction (XRD), Rietveld method, thermogravimetric analysis (TGA) and electrical conductivity to apply these oxide materials for the HT-SOFC anode materials. XRD results showed that Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} oxide systems synthesized as single phases did not react with 8 mol% yttriamore » stabilized zirconia (8YSZ) and 10 mol% Gd-doped cerium oxide (CGO91) up to 1500 °C and did not decompose under dry 3.9% hydrogen at 850 °C. The crystal structures of La{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (LSTM), Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (NSTM) and Sm{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (SSTM) showed orthorhombic symmetry with the space group Pbnm and SSTM showed a more distorted structure. Thermogravimetric analysis (TGA) proved weight gains in these three sample occurred under oxidizing conditions and weight loss under reducing conditions. Electrical conductivity values of NSTM were higher than those of LSTM and SSTM under oxidizing and reducing conditions. - Graphical abstract: The B-site cations (Ti/Mn) are surrounded by regular octahedra of oxygen in Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}(NSTM). These octahedra are linked together in a corner sharing three dimensional framework, while Nd/Sr ion occupies 12-coordinated A-site between these octahedra. The Ti/Mn–O{sub 6} octahedra are elongated along the c-axis. The crystal structure distortion was due to the smaller ionic radius of the A-site cations, which force the (Ti

  18. Tailoring optical properties of TiO2-Cr co-sputtered films using swift heavy ions

    NASA Astrophysics Data System (ADS)

    Gupta, Ratnesh; Sen, Sagar; Phase, D. M.; Avasthi, D. K.; Gupta, Ajay

    2018-05-01

    Effect of 100 MeV Au7+ ion irradiation on structure and optical properties of Cr-doped TiO2 films has been studied using X-ray photoelectron spectroscopy, soft X-ray absorption spectroscopy, UV-Visible spectroscopy, X-ray reflectivity, and atomic force microscopy. X-ray reflectivity measurement implied that film thickness reduces as a function of ion fluence while surface roughness increases. The variation in surface roughness is well correlated with AFM results. Ion irradiation decreases the band gap energy of the film. Swift heavy ion irradiation enhances the oxygen vacancies in the film, and the extra electrons in the vacancies act as donor-like states. In valence band spectrum, there is a shift in the Ti3d peak towards lower energies and the shift is equivalent to the band gap energy obtained from UV spectrum. Evidence for band bending is also provided by the corresponding Ti XPS peak which exhibits a shift towards lower energy due to the downward band bending. X-ray absorption studies on O Kand Cr L3,2 edges clearly indicate that swift heavy ion irradiation induces formation of Cr-clusters in TiO2 matrix.

  19. Structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics for a-IGZO thin-film transistors

    PubMed Central

    2013-01-01

    In this letter, we investigated the structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics on the amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) devices. Compared with the Er2O3 dielectric, the a-IGZO TFT device incorporating an Er2TiO5 gate dielectric exhibited a low threshold voltage of 0.39 V, a high field-effect mobility of 8.8 cm2/Vs, a small subthreshold swing of 143 mV/decade, and a high Ion/Ioff current ratio of 4.23 × 107, presumably because of the reduction in the oxygen vacancies and the formation of the smooth surface roughness as a result of the incorporation of Ti into the Er2TiO5 film. Furthermore, the reliability of voltage stress can be improved using an Er2TiO5 gate dielectric. PMID:23294730

  20. Structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics for a-IGZO thin-film transistors.

    PubMed

    Chen, Fa-Hsyang; Her, Jim-Long; Shao, Yu-Hsuan; Matsuda, Yasuhiro H; Pan, Tung-Ming

    2013-01-08

    In this letter, we investigated the structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics on the amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) devices. Compared with the Er2O3 dielectric, the a-IGZO TFT device incorporating an Er2TiO5 gate dielectric exhibited a low threshold voltage of 0.39 V, a high field-effect mobility of 8.8 cm2/Vs, a small subthreshold swing of 143 mV/decade, and a high Ion/Ioff current ratio of 4.23 × 107, presumably because of the reduction in the oxygen vacancies and the formation of the smooth surface roughness as a result of the incorporation of Ti into the Er2TiO5 film. Furthermore, the reliability of voltage stress can be improved using an Er2TiO5 gate dielectric.

  1. 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.

  2. Biocorrosion of TiO2 nanoparticle coating of Ti-6Al-4V in DMEM under specific in vitro conditions

    NASA Astrophysics Data System (ADS)

    Höhn, Sarah; Virtanen, Sannakaisa

    2015-02-01

    A TiO2 nanoparticle coating was prepared on a biomedical Ti-6Al-4V alloy using "spin-coating" technique with a colloidal suspension of TiO2 nanopowders with the aim to optimize the surface morphology (e.g., roughness) for improved biocompatibility. The influence of a TiO2 nanoparticle (NP) coating on the corrosion behavior, metal ion release, and biomimetic apatite formation was studied in DMEM, at 37.5 °C with a continuous supply of 5% CO2. Electrochemical impedance spectroscopy measurements indicate a formation of a new layer on the surface of the NP-coated sample upon 28 days immersion in DMEM. Scanning electron microscopy (SEM) and X-ray spectroscopy confirm that the surface of the NP-coated Ti-6Al-4V shows a complete coverage by a Ca-phosphate layer in contrast to the non-coated Ti-6Al-4V alloy. Hence, the TiO2-NP coating strongly enhances biomimetic apatite formation on the alloy surface. In addition, the TiO2-NP coating can efficiently reduce Al-release from the alloy, for which the bare Ti-6Al-4V alloy is significant for at least 28 days of immersion in DMEM.

  3. Structure and temperature-dependent phase transitions of lead-free Bi 1/2Na 1/2TiO 3-Bi 1/2K 1/2TiO 3-K 0.5Na 0.5NbO 3 piezoceramics

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

    Anton, Eva-Maria; Schmitt, Ljubomira Ana; Hinterstein, Manuel

    2014-05-28

    Structure and phase transitions of (1-y)((1-x)Bi 1/2Na 1/2TiO 3-xBi 1/2K 1/2TiO 3)-yK 0.5Na 0.5NbO 3 (x; y) piezoceramics (0.1 ≤ x ≤ 0.4; 0 ≤ y ≤ 0.05) were investigated by transmission electron microscopy, neutron diffraction, temperature-dependent x-ray diffraction, and Raman spectroscopy. The local crystallographic structure at room temperature (RT) does not change by adding K 0.5Na 0.5NbO 3 to Bi 1/2Na 1/2TiO 3-xBi 1/2K 1/2TiO 3 for x = 0.2 and 0.4. The average crystal structure and microstructure on the other hand develop from mainly long-range polar order with ferroelectric domains to short-range order with polar nanoregions displaying amore » more pronounced relaxor character. The (0.1; 0) and (0.1; 0.02) compositions exhibit monoclinic Cc space group symmetry, which transform into Cc + P4bm at 185 and 130 °C, respectively. This high temperature phase is stable at RT for the morphotropic phase boundary compositions of (0.1; 0.05) and all compositions with x = 0.2. For the compositions of (0.1; 0) and (0.1; 0.02), local structural changes on heating are evidenced by Raman; for all other compositions, changes in the long-range average crystal structure were observed.« less

  4. Relative susceptibility of titanium alloys to hot-salt stress-corrosion

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1971-01-01

    Susceptibility of titanium alloys to hot-salt stress-corrosion cracking increased as follows: Ti-2Al-11Sn-5Zr-0.2Si(679), Ti-6Al-2Sn-4Zr-2Mo(6242), Ti-6Al-4V(64), Ti-6Al-4V-3Co(643), Ti-8Al-1Mo-1V(811), and Ti-13V-11Cr-3A1(13-11-3). The Ti-5Al-6Sn-2Zr-1Mo-0.25Si(5621S) alloy was both the least and most susceptible depending on heat treatment. Such rankings can be drastically altered by heat-to-heat and processing variations. Residual compressive stresses and cyclic exposures also reduce susceptibility to stress-corrosion. Simulated turbine-engine compressor environmental variables such as air velocity, pressure, dewpoint, salt concentration, and salt deposition temperature have only minor effects. Detection of substantial concentrations of hydrogen in all corroded alloys confirmed the existence of a hydrogen embrittlement mechanism.

  5. Chemical and electrochemical behavior of the Cr(III)/Cr(II) half-cell in the iron-chromium redox energy storage system

    NASA Technical Reports Server (NTRS)

    Johnson, D. A.; Reid, M. A.

    1985-01-01

    The Cr(III) complexes present in the acidified chromium solutions used in the iron-chromium redox energy storage system have been isolated and identified as Cr(H2O)6(3+) and Cr(H2O)5Cl(2+) by ion-exchange chromatography and visible spectrophotometry. The cell reactions during charge-discharge cycles have been followed by means of visible spectrophotometry. The spectral bands were resolved into component peaks and concentrations of the Cr(III) species calculated using Beer's law. During the charge mode, Cr(H2O)5Cl(2+) is reduced to Cr(H2O)5Cl(+), and during the discharge mode Cr(H2O)5Cl(+) is oxidized back to Cr(H2O)5Cl(2+). Electrode potential measurements also support this interpretation. Hysteresis effects in the charge-discharge curves can be explained by the slow attainment of equilibrium between Cr(H2O)6(3+) and Cr(H2O)5Cl(2+).

  6. Experimental Constraints on the Origin of Lunar High-Ti Ultramafic Glasses

    NASA Technical Reports Server (NTRS)

    Wagner, T. P.; Grove, T. L.

    1996-01-01

    Phase equilibria and dissolution rate experiments are used to develop a petrogenetic model for the high-Ti lunar ultramafic glasses. Near-liquidus phase relations of the Apollo 14 black glass, the most Ti-rich lunar ultramafic glass, are determined to 2.2-GPa. The liquidus is saturated with Cr-spinel at 1-atm, olivine between approximately 0.5- and 1.5-GPa, and low-Ca pyroxene + Cr-spinel above 1.5-GPa. Ilmenite does not crystallize near the liquidus and implies that high-Ti ultramafic glasses are not produced by melting of an ilmenite-saturated source. We infer that high-Ti ultramafic magmas are derived from low-Ti ultramafic parent magmas by assimilation of ilmenite +/- clinopyroxene +/- urKREEP +/- pigeonite in the shallow lunar interior. Heat is provided by adiabatic ascent of the low-Ti ultramafic primary magmas from the deeper lunar interior and crystallization of olivine during assimilation. The assimilation reaction is modeled by mass balance and requires that ilmenite and high-Ca pyroxene are assimilated in a approximately 3:1 ratio, a much higher ratio than the proportion in which these minerals are thought to exist in the lunar interior. In an effort to understand the kinetic controls on this reaction, the dissolution of ilmenite is examined experimentally in both low- and high-Ti lunar magmas. We find that ilmenite dissolves incongruently to Cr-spinel and a high-Ti melt. The dissolution reaction proceeds by a diffusion-controlled mechanism. An assimilation model for the origin of high-Ti melts is developed that leaves the magma ocean cumulates in their initial stratigraphic positions and obviates source hybridization models that require lunar overturn.

  7. Controlling Solid-Electrolyte-Interphase Layer by Coating P-Type Semiconductor NiOx on Li4Ti5O12 for High-Energy-Density Lithium-Ion Batteries.

    PubMed

    Jo, Mi Ru; Lee, Gi-Hyeok; Kang, Yong-Mook

    2015-12-23

    Li4Ti5O12 is a promising anode material for rechargeable lithium batteries due to its well-known zero strain and superb kinetic properties. However, Li4Ti5O12 shows low energy density above 1 V vs Li(+)/Li. In order to improve the energy density of Li4Ti5O12, its low-voltage intercalation behavior beyond Li7Ti5O12 has been demonstrated. In this approach, the extended voltage window is accompanied by the decomposition of liquid electrolyte below 1 V, which would lead to an excessive formation of solid electrolyte interphase (SEI) films. We demonstrate an effective method to improve electrochemical performance of Li4Ti5O12 in a wide working voltage range by coating Li4Ti5O12 powder with p-type semiconductor NiOx. Ex situ XRD, XPS, and FTIR results show that the NiOx coating suppresses electrochemical reduction reactions of the organic SEI components to Li2CO3, thereby promoting reversibility of the charge/discharge process. The NiOx coating layer offers a stable SEI film for enhanced rate capability and cyclability.

  8. Fatty acid elongase-5 (Elovl5) regulates hepatic triglyceride catabolism in obese C57BL/6J mice[S

    PubMed Central

    Tripathy, Sasmita; Lytle, Kelli A.; Stevens, Robert D.; Bain, James R.; Newgard, Christopher B.; Greenberg, Andrew S.; Huang, Li-Shin; Jump, Donald B.

    2014-01-01

    Nonalcoholic fatty liver disease is a major public health concern in the obese and type 2 diabetic populations. The high-fat lard diet induces obesity and fatty liver in C57BL/6J mice and suppresses expression of the PPAR-target gene, FA elongase 5 (Elovl5). Elovl5 plays a key role in MUFA and PUFA synthesis. Increasing hepatic Elovl5 activity in obese mice lowered hepatic TGs and endoplasmic reticulum stress markers (X-box binding protein 1 and cAMP-dependent transcription factor 6α) and increased TG catabolism and fatty acyl carnitines. Increased hepatic Elovl5 activity did not increase hepatic capacity for β-oxidation. Elovl5 effects on hepatic TG catabolism were linked to increased protein levels of adipocyte TG lipase (ATGL) and comparative gene identification 58 (CGI58). Elevated hepatic Elovl5 activity also induced the expression of some (pyruvate dehydrogenase kinase 4 and fibroblast growth factor 21), but not other cytochrome P450 4A10 (CYP4A10), PPAR-target genes. FA products of Elovl5 activity increased ATGL, but not CGI58, mRNA through PPARβ-dependent mechanisms in human HepG2 cells. Treatment of mouse AML12 hepatocytes with the PPARβ agonist (GW0742) decreased 14C-18:2,n-6 in TGs but did not affect β-oxidation. These studies establish that Elovl5 activity regulates hepatic levels of FAs controlling PPARβ activity, ATGL expression, and TG catabolism, but not FA oxidation. PMID:24814977

  9. Laser Cladding of Ti-6Al-4V Alloy with Ti-Al2O3 Coating for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Mthisi, A.; Popoola, A. P. I.; Adebiyi, D. I.; Popoola, O. M.

    2018-05-01

    The indispensable properties of Ti-6Al-4V alloy coupled with poor tribological properties and delayed bioactivity make it a subject of interest to explore in biomedical application. A quite number of numerous coatings have been employed on titanium alloys, with aim to overcome the poor properties exhibited by this alloy. In this work, the possibility of laser cladding different ad-mixed powders (Ti - 5 wt.% Al2O3 and Ti - 8wt.% Al2O3) on Ti-6Al-4V at various laser scan speed (0.6 and 0.8 m/min) were investigated. The microstructure, phase constituents and corrosion of the resultant coatings were characterized by scanning electron microscope (SEM), Optical microscope, X-Ray diffractometer (XRD) and potentiostat respectively. The electrochemical behaviour of the produced coatings was studied in a simulated body fluid (Hanks solution). The microstructural results show that a defect free coating is achieved at low scan speed and ad-mixed of Ti-5 wt. % Al2O3. Cladding of Ti - Al2O3 improved the corrosion resistance of Ti-6Al-4V alloy regardless of varying neither scan speed nor ad-mixed percentage. However, Ti-5 wt.% Al2O3 coating produced at low scan speed revealed the highest corrosion resistance among the coatings due to better quality coating layer. Henceforth, this coating may be suitable for biomedical applications.

  10. Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study.

    PubMed

    Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

    2013-12-01

    The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5-216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO2 phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets.

  11. Prediction of Fracture Initiation in Hot Compression of Burn-Resistant Ti-35V-15Cr-0.3Si-0.1C Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Saifei; Zeng, Weidong; Zhou, Dadi; Lai, Yunjin

    2015-11-01

    An important concern in hot working of metals is whether the desired deformation can be accomplished without fracture of the material. This paper builds a fracture prediction model to predict fracture initiation in hot compression of a burn-resistant beta-stabilized titanium alloy Ti-35V-15Cr-0.3Si-0.1C using a combined approach of upsetting experiments, theoretical failure criteria and finite element (FE) simulation techniques. A series of isothermal compression experiments on cylindrical specimens were conducted in temperature range of 900-1150 °C, strain rate of 0.01-10 s-1 first to obtain fracture samples and primary reduction data. Based on that, a comparison of eight commonly used theoretical failure criteria was made and Oh criterion was selected and coded into a subroutine. FE simulation of upsetting experiments on cylindrical specimens was then performed to determine the fracture threshold values of Oh criterion. By building a correlation between threshold values and the deforming parameters (temperature and strain rate, or Zener-Hollomon parameter), a new fracture prediction model based on Oh criterion was established. The new model shows an exponential decay relationship between threshold values and Zener-Hollomon parameter (Z), and the relative error of the model is less than 15%. This model was then applied successfully in the cogging of Ti-35V-15Cr-0.3Si-0.1C billet.

  12. Laser Powder Cladding of Ti-6Al-4V α/β Alloy

    PubMed Central

    Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

    2017-01-01

    Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times. PMID:29036935

  13. Laser Powder Cladding of Ti-6Al-4V α/β Alloy.

    PubMed

    Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Hasseb Elnaby, Salah Elden Ibrahim; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

    2017-10-15

    Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm -2 . An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

  14. Design, properties, and weldability of advanced oxidation-resistant FeCrAl alloys

    DOE PAGES

    Gussev, M. N.; Field, K. G.; Yamamoto, Y.

    2017-05-05

    FeCrAl alloys are promising as corrosion- and oxidation-resistance materials for extreme high-temperature applications. However, further alloy design and improvement requires a delicate balance between workability, weldability, propensity for '-phase formation, among other factors. Here, a series of advanced oxidant resistant FeCrAl alloys were produced and investigated. Variants with Al (+2%), Nb (+1%), and TiC (0.1, 0.3, and 1%) additions over the reference alloy (Fe-13%Cr-5%Al) were characterized in detail before and after controlled laser beam welding using tensile tests with digital image correlation, SEM-EBSD analysis, and fractography. All investigated alloys demonstrated yield stress in the weldment over 500 MPa; no welding-inducedmore » cracking was observed. However, it was shown that the increase in the Al-content over 5% was detrimental leading to a brittle fracture mechanism and decreased ductility in the weldment. At the same time, Nb and TiC additions were beneficial for preventing grain growth and reducing local softening (yield stress reduction) in the heat-affected zone. The 1% TiC addition also effectively refined grain size in the weldment.« less

  15. Design, properties, and weldability of advanced oxidation-resistant FeCrAl alloys

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

    Gussev, M. N.; Field, K. G.; Yamamoto, Y.

    FeCrAl alloys are promising as corrosion- and oxidation-resistance materials for extreme high-temperature applications. However, further alloy design and improvement requires a delicate balance between workability, weldability, propensity for '-phase formation, among other factors. Here, a series of advanced oxidant resistant FeCrAl alloys were produced and investigated. Variants with Al (+2%), Nb (+1%), and TiC (0.1, 0.3, and 1%) additions over the reference alloy (Fe-13%Cr-5%Al) were characterized in detail before and after controlled laser beam welding using tensile tests with digital image correlation, SEM-EBSD analysis, and fractography. All investigated alloys demonstrated yield stress in the weldment over 500 MPa; no welding-inducedmore » cracking was observed. However, it was shown that the increase in the Al-content over 5% was detrimental leading to a brittle fracture mechanism and decreased ductility in the weldment. At the same time, Nb and TiC additions were beneficial for preventing grain growth and reducing local softening (yield stress reduction) in the heat-affected zone. The 1% TiC addition also effectively refined grain size in the weldment.« less

  16. Influence of thermomechanical processing on biomechanical compatibility and electrochemical behavior of new near beta alloy, Ti-20.6Nb-13.6Zr-0.5V

    PubMed Central

    Mohammed, Mohsin Talib; Khan, Zahid A; Manivasagam, Geetha; Siddiquee, Arshad N

    2015-01-01

    This paper presents the results for the effect of different methods of thermomechanical processing on the mechanical properties and electrochemical behavior of metastable β alloy Ti-20.6Nb-13.6Zr-0.5V (TNZV). The thermomechanical processing included hot working, solution heat treatments at different temperatures, and cooling rates in addition to aging. The thermomechanical processing conditions used in the study resulted in attainment of a wide range of microstructures with varying spatial distributions and morphologies of elongated/equiaxed α, β phases, or martensite, as a result of which several tensile properties were achieved. Aging treatment led to an increase in hardness, elastic modulus, and tensile strength and a decrease in ductility (elongation). Electrochemical tests indicated that the TNZV alloy undergoes spontaneous passivation due to spontaneous formation of an oxide film in the environment of the human body. Because the air-cooled samples possessed high hardness and also a fine grain size, they showed a lower corrosion rate than the samples treated under other conditions. PMID:26491324

  17. H2O2/HCl and heat-treated Ti-6Al-4V stimulates pre-osteoblast proliferation and differentiation.

    PubMed

    Shi, Geng-sheng; Ren, Ling-fei; Wang, Lin-zhi; Lin, Hai-sheng; Wang, Sha-bin; Tong, Yong-qing

    2009-09-01

    The purpose of the present study was to evaluate the bioactivity of chemical treatment of titanium alloy (Ti-6Al-4V) in vitro. Smooth-surface discs of Ti-6Al-4V were used in this study. Sandblasted, dual acid-etched and H(2)O(2)/HCl heat-treated discs were set as test group, and sandblasted, dual acid-etched discs as control group. SEM and XRD analysis revealed a porous anatase gel layer on rough surface in the test group and a rough surface in the control group. Mouse pre-osteoblasts (MC3T3-E1 cells) were cultured on these 2 group discs, and then cell proliferation and differentiation were examined 4 days, 7 days, and 14 days after cell seeding. Cell proliferation was greatly stimulated at all time points when cultured in test group (P < .05). The alkaline phosphatase (ALP) activity and osteocalcin (OC) production were much higher in the test group compared with the control group at every time point investigated (P < .05). Furthermore, in the test group, the expressions of alkaline phosphatase-2, osteocalcin, and collagen type I alpha 1 mRNAs were significantly up-regulated as compared with those in the control group (P < .05 or P < .01). The results suggested that H(2)O(2)/HCl and heat-treatment might facilitate better integration of Ti-6Al-4V implants with bone.

  18. Annealing induced effect on the physical properties of ion-beam sputtered 0.5 Ba(Zr0.2Ti0.8)O3 - 0.5 (Ba0.7Ca0.3)TiO3-δ ferroelectric thin films

    NASA Astrophysics Data System (ADS)

    Oliveira, M. J. S.; Silva, J. P. B.; Veltruská, Kateřina; Matolín, V.; Sekhar, K. C.; Moreira, J. Agostinho; Pereira, M.; Gomes, M. J. M.

    2018-06-01

    This work reports thermal annealing induced effect on the structural, optical, chemical and ferroelectric properties of ion-beam sputtered lead-free ferroelectric 0.5 Ba(Zr0.2Ti0.8)O3 - 0.5 (Ba0.7Ca0.3)TiO3-δ (0.5BZT-0.5BCT) thin films. X-ray diffraction studies reveal that the tetragonality increases with the annealing temperature (Ta), while photoluminescence and X-ray photoelectron spectroscopy studies confirm that this effect is associated with the annihilation of the oxygen vacancies as well as changes in the Ba2+ coordination. The films annealed at 750 °C show a remarkable remnant polarization of Pr = 45.0 μC/cm2, with a coercive field of 32 kV/cm. The temperature dependence of the spontaneous polarization of the 0.5BZT-0.5BCT film reveals a mean field behavior of the polarization and the fatigue study reveals that Pr only decreases 3% after passing 109 cycles. Therefore the high remnant polarization and its high Pr stability make these films as promising candidates for memory applications.

  19. Structural, Optical and Impedance Spectroscopic Characterizations of Nanocrystalline A2Ti2Zr5O16 (A = Mg, Ca, Ba and Sr)

    NASA Astrophysics Data System (ADS)

    Sandeep, K.; Thomas, Jijimon K.; Solomon, Sam

    2018-04-01

    A nanocrystalline A2Ti2Zr5O16 (A = Mg, Ca, Ba and Sr) system has been synthesized by a modified combustion technique. The cation-deficient calzirtite (Ca2Ti2Zr5O16) is found to be a tetragonal structure with the space group I4(1)/acd. The average size of the particle from the transmission electron microscopy image is estimated to be 23.30 nm and 20.16 nm for Ca2Ti2Zr5O16 and Ba2Ti2Zr5O16, respectively. The optical bandgap calculated using a Tauc plot is between 3.01 eV and 3.46 eV. Raman and Fourier transform infrared spectroscopy (FTIR) studies were carried out to confirm the phase purity of the sample. The scanning electron microscopy (SEM) image of a Ca2Ti2Zr5O16 sample sintered at 1360°C for 3 h shows minimum porosity with 96% of the theoretical density. The frequency-dependent dielectric study shows that the dielectric constant is maximized at low frequencies and decreases as the frequency increases. The Cole-Cole plot reveals that the material exhibits conduction due to the contributions of grain, grain boundary and electrode effects. The photoluminescence spectra of the samples were recorded and the transitions causing emission have been identified.

  20. Large magnetic response in (Bi4Nd)Ti3(Fe0.5Co0.5)O15 ceramic at room-temperature

    NASA Astrophysics Data System (ADS)

    Yang, F. J.; Su, P.; Wei, C.; Chen, X. Q.; Yang, C. P.; Cao, W. Q.

    2011-12-01

    Ceramics of Nd/Co co-substituted Bi5Ti3FeO15, i.e., (Bi4Nd)Ti3(Fe0.5Co0.5)O15 were prepared by the conventional solid-state reaction method. The X-ray diffraction pattern demonstrates that the sample of the layered perovskite phase was successfully obtained, even if little Bi-deficient pyrochlore Bi2Ti2O7 also existed. The ferroelectric and magnetic Curie temperatures were determined to be 1077 K and 497 K, respectively. The multiferroic property of the sample at room temperature was demonstrated by ferroelectric and magnetic measurements. Remarkably, by Nd/Co co-substituting, the sample exhibited large magnetic response with 2Mr = 330 memu/g and 2Hc = 562 Oe at applied magnetic field of 8 kOe at room temperature. The present work suggests the possibility of doped Bi5Ti3FeO15 as a potential multiferroic.

  1. Effect of Heat Input on the Tensile Damage Evolution in Pulsed Laser Welded Ti6Al4V Titanium Sheets

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Gao, Xiaolong; Zhang, Jianxun

    2016-11-01

    The present paper is focused on studying the effect of heat input on the tensile damage evolution of pulsed Nd:YAG laser welding of Ti6Al4V alloy under monotonic loading. To analyze the reasons that the tensile fracture site of the pulsed-laser-welded Ti6Al4V sheet joints changes with the heat input under monotonic loading, the microstructure of the sample with different nominal strain values was investigated by in situ observation. Experiment results show that the tensile ductility and fatigue life of welded joints with low heat input are higher than that of welded joints with high heat input. Under tensile loads, the critical engineering strain for crack initiation is much lower in the welded joint with high heat input than in the welded joints with low and medium heat input. And the microstructural damage accumulation is much faster in the fusion zone than in the base metal for the welded joints with high input, whereas the microstructural damage accumulation is much faster in the base metal than in the fusion zone for the welded joints with low input. Consequently, the welded joints fractured in the fusion zone for the welds with high heat input, whereas the welded joints ruptured in the base metal for the welds with low heat input. It is proved that the fine grain microstructure produced by low heat input can improve the critical nominal strain for crack initiation and the resistance ability of microstructural damage.

  2. Estimation of Joule heating and its role in nonlinear electrical response of Tb0.5Sr0.5MnO3 single crystal

    NASA Astrophysics Data System (ADS)

    Nhalil, Hariharan; Elizabeth, Suja

    2016-12-01

    Highly non-linear I-V characteristics and apparent colossal electro-resistance were observed in non-charge ordered manganite Tb0.5Sr0.5MnO3 single crystal in low temperature transport measurements. Significant changes were noticed in top surface temperature of the sample as compared to its base while passing current at low temperature. By analyzing these variations, we realize that the change in surface temperature (ΔTsur) is too small to have caused by the strong negative differential resistance. A more accurate estimation of change in the sample temperature was made by back-calculating the sample temperature from the temperature variation of resistance (R-T) data (ΔTcal), which was found to be higher than ΔTsur. This result indicates that there are large thermal gradients across the sample. The experimentally derived ΔTcal is validated with the help of a simple theoretical model and estimation of Joule heating. Pulse measurements realize substantial reduction in Joule heating. With decrease in sample thickness, Joule heating effect is found to be reduced. Our studies reveal that Joule heating plays a major role in the nonlinear electrical response of Tb0.5Sr0.5MnO3. By careful management of the duty cycle and pulse current I-V measurements, Joule heating can be mitigated to a large extent.

  3. First-principles study on the structural, elastic and electronic properties of Ti4N3 and Ti6N5 under high pressure

    NASA Astrophysics Data System (ADS)

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

    2017-12-01

    The structural, elastic and electronic properties of Ti4N3 and Ti6N5 have been systematically studied by first-principles calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) and local density approximation (LDA). Basic physical properties for Ti4N3 and Ti6N5, such as the lattice constants, the bulk modulus, shear modulus, and elastic constants are calculated. The results show that Ti4N3 and Ti6N5 are mechanically stable under ambient pressure. The phonon dispersion spectra are researched throughout the Brillouin zone via the linear response approach as implemented in the CASTEP code, which indicate the optimized structures are stable dynamically. The Young’s modulus E and Poisson’s ratios ν are also determined within the framework of the Voigt-Reuss-Hill approximation. The analyses show that Ti4N3 is more ductile than Ti6N5 at the same pressure and ductility increases as the pressure increases. Moreover, the anisotropies of the Ti4N3 and Ti6N5 are discussed by the Young’s modulus at different directions, and the results indicate that the anisotropy of the two Ti-N compounds is obvious. The total density of states (TDOS) and partial density of states (PDOS) show that the TDOS of TiN, Ti4N3 and Ti6N5 originate mainly from Ti “d” and N “p” states. The results show that Ti4N3 and Ti6N5 present semimetal character. Pressure makes the level range of DOS significantly extended, for TiN, Ti4N3 and Ti6N5. The TDOS decreases with the pressure rise, at Fermi level.

  4. Fabrication, microstructure and electrical conductivity of V{sub 2}O{sub 5} ceramics

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

    Honma, K.; Yoshinaka, M.; Hirota, K.

    1996-05-01

    V{sub 2}O{sub 5} gels corresponding to the formula V{sub 2}O{sub 5} {center_dot} nH{sub 2}O with n = 2.07, 0.5, and 0.2 have been prepared by the hydrolysis of VO(OC{sub 2}H{sub 5}){sub 3}, followed by washing and drying. After dehydration, V{sub 2}O{sub 5} crystallizes at 310--400 C. V{sub 2}O{sub 5} powders with strip-like particles are produced after heating at 630 C. Well-densified V{sub 2}O{sub 5} ceramics (97.7% of theoretical) have been fabricated by the combined use of hot pressing (630C/2h/30MPa) and hot isostatic pressing (630 C/1h/196MPa). The texture is of a plate structure, the grain being {approx}30 {micro}m long and {approx}6more » {micro}m wide. Electrical conductivities have been measured in the temperature range of 25--600 C. Activation energies are determined to be 0.09 and 0.18 eV for initial and final stages, respectively.« less

  5. Overview of the new capabilities of TORIC-v6 and comparison with TORIC-v5

    NASA Astrophysics Data System (ADS)

    Bilato, R.; Brambilla, M.; Bertelli, N.

    2016-10-01

    Since its release, version 5 (v5) of the full-wave TORIC code, characterized by an optimized parallelized solver for its routinely use in TRANSP package, has been ameliorated in many technical issues, e.g. the plasma-vacuum transition and the full-spectrum antenna modeling. For the WPCD-benchmark cases a good agreement between the new version, v6, and v5 is found. The major improvement, however, has been done in interfacing TORIC-v6 with the Fokker-Planck SSFPQL solver to account for the back-reaction of ICRF and NBI heating on the wave propagation and absorption. Special algorithms have been developed for SSFPQL for the numerical precision at high pitch-angle resolution and to evaluate the generalized dispersion function directly from the numerical solution. Care has been spent in automatizing the non-linear loop between TORIC-v6 and SSFPQL. In v6 the description of wave absorption at high-harmonics has been revised and applied to DEMO. For high-harmonic regimes there is an ongoing activity on the comparison with AORSA.

  6. Manipulating multiple order parameters via oxygen vacancies: The case of E u0.5B a0.5Ti O3 -δ

    NASA Astrophysics Data System (ADS)

    Li, Weiwei; He, Qian; Wang, Le; Zeng, Huizhong; Bowlan, John; Ling, Langsheng; Yarotski, Dmitry A.; Zhang, Wenrui; Zhao, Run; Dai, Jiahong; Gu, Junxing; Shen, Shipeng; Guo, Haizhong; Pi, Li; Wang, Haiyan; Wang, Yongqiang; Velasco-Davalos, Ivan A.; Wu, Yangjiang; Hu, Zhijun; Chen, Bin; Li, Run-Wei; Sun, Young; Jin, Kuijuan; Zhang, Yuheng; Chen, Hou-Tong; Ju, Sheng; Ruediger, Andreas; Shi, Daning; Borisevich, Albina Y.; Yang, Hao

    2017-09-01

    Controlling functionalities, such as magnetism or ferroelectricity, by means of oxygen vacancies (VO) is a key issue for the future development of transition-metal oxides. Progress in this field is currently addressed through VO variations and their impact on mainly one order parameter. Here we reveal a mechanism for tuning both magnetism and ferroelectricity simultaneously by using VO. Combining experimental and density-functional theory studies of E u0.5B a0.5Ti O3 -δ , we demonstrate that oxygen vacancies create T i3 +3 d1 defect states, mediating the ferromagnetic coupling between the localized Eu 4 f7 spins, and increase an off-center displacement of Ti ions, enhancing the ferroelectric Curie temperature. The dual function of Ti sites also promises a magnetoelectric coupling in the E u0.5B a0.5Ti O3 -δ .

  7. An evaluation of the susceptibility of V-4Cr-4Ti to stress corrosion cracking in room temperature DIII-D water

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

    Kurtz, R.J.; Jones, R.H.; Johnson, W.R.

    1997-04-01

    Two fatigue precracked compact tension (CT) specimens of V-4Cr-4Ti were statically loaded to a stress intensity factor of about 30 MPa{radical}m in room temperature DIII-D water. The first specimen was tested for a period of about 30 days and the second specimen for about 54 days. At the conclusion of each test the specimens were fractured, and the fracture surfaces examined with a scanning electron microscope (SEM) to determine if SCC had occurred. No SCC was found in either test specimen.

  8. Superconductivity at 5 K in quasi-one-dimensional Cr-based KCr3As3 single crystals

    NASA Astrophysics Data System (ADS)

    Mu, Qing-Ge; Ruan, Bin-Bin; Pan, Bo-Jin; Liu, Tong; Yu, Jia; Zhao, Kang; Chen, Gen-Fu; Ren, Zhi-An

    2017-10-01

    Recently a new family of Cr-based A2Cr3As3 (A =K , Rb, Cs) superconductors was reported, which own a rare quasi-one-dimensional (Q1D) crystal structure with infinite (Cr3As3) 2 - chains and exhibit intriguing superconducting characteristics possibly derived from spin-triplet electron pairing. The crystal structure of A2Cr3As3 is actually a slight variation of the hexagonal TlFe3Te3 prototype, although they have different lattice symmetry. Here we report superconductivity in a 133-type KCr3As3 compound that belongs to the latter structure. The single crystals of KCr3As3 were prepared by the deintercalation of K ions from K2Cr3As3 crystals which were grown from a high-temperature solution growth method, and it owns a centrosymmetric lattice in contrast to the noncentrosymmetric K2Cr3As3 . After annealing at a moderate temperature, the KCr3As3 crystals show superconductivity at 5 K revealed by electrical resistivity, magnetic susceptibility, and heat capacity measurements. The discovery of this KCr3As3 superconductor provides a different structural instance to study the exotic superconductivity in these Q1D Cr-based superconductors.

  9. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17%Cr and Cu-17%Cr-5%Al. Part 1; Oxidation Kinetics

    NASA Technical Reports Server (NTRS)

    Raj. Sai V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu- 17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 +/- 9.5 kJ/mol. In contrast, the oxidation kinetics for the Cu-17%Cr- 5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR- 5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.

  10. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17%Cr and Cu-17%Cr-5%Al. Part 1; Oxidation Kinetics

    NASA Technical Reports Server (NTRS)

    Raj. Sai V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu- 17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 9.5 kJ mol-1. In contrast, the oxidation kinetics for the Cu-17%Cr- 5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR- 5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.

  11. 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.

  12. AC conductivity studies of La doped Ba0.5Sr0.5TiO3

    NASA Astrophysics Data System (ADS)

    D'Souza, Slavia Deeksha; Rohith, Kotla Surya; Bhatnagar, Anil K.; Kumar, A. Sendil

    2017-05-01

    Ferroelectric material with high dielectric constant of Ba0.5Sr0.5TiO3 is synthesized through Solid State Reaction and fraction of Lanthanum is substituted to introduce hole concentration. XRay Diffraction shows all the samples are stabilized in cubic crystal structure. With La doped samples the Cole-Cole plot is modified and AC conductivity increases at higher temperatures as well as higher frequencies compared to undoped sample.

  13. Enhanced torsional actuation and stress coupling in Mn-modified 0.93(Na0.5Bi0.5TiO3)-0.07BaTiO3 lead-free piezoceramic system

    PubMed Central

    Berik, Pelin; Maurya, Deepam; Kumar, Prashant; Kang, Min Gyu; Priya, Shashank

    2017-01-01

    Abstract This paper is concerned with the development of a piezoelectric d 15 shear-induced torsion actuator made of a lead-free piezoceramic material exhibiting giant piezoelectric shear stress coefficient (e 15) and piezoelectric transverse shear actuation force comparable to that of lead-based shear-mode piezoceramics. The Mn-modified 0.93(Na0.5Bi0.5TiO3)-0.07BaTiO3 (NBT-BT-Mn) composition exhibited excellent properties as a torsional transducer with piezoelectric shear stress coefficient on the order of 11.6 C m–2. The torsional transducer, consisting of two oppositely polarized NBT-BT-Mn d 15 mode piezoceramic shear patches, provided a rate of twist of 0.08 mm m–1 V–1 under quasi-static 150 V drive. The high value of piezoelectric shear d 15 coefficient in NBT-BT-Mn sample further demonstrated its potential in practical applications. These results confirm that the lead-free piezoceramics can be as effective as their lead-based counterparts. PMID:28179958

  14. Toward understanding the lithiation/delithiation process in Fe 0.5TiOPO 4/C electrode material for lithium-ion batteries

    DOE PAGES

    Lasri, Karima; Mahmoud, Abdelfattah; Saadoune, Ismael; ...

    2015-11-28

    We used Fe 0.5TiOPO 4/C composite as anode material for LIB and exhibits excellent cycling performance when the electrode is cycled in two different voltage ranges [3.0-1.3V] and [3.0- 0.02V] where different insertion mechanisms were involved. Based on in situ X-ray diffraction, in situ XANES spectroscopy results, and various electrochemical analyses at high and low voltage cut-off, we found that Fe 0.5TiOPO 4/C electrode materials still maintains its structure crystallinity after cycling between [3.0-1.3V] showing formation of new phase at the end of first discharge, with a reversible capacity of 100 mAhg-1 after 50 cycles at C/5 rate. Moreover, atmore » highly lithiated states, [3.0-0.02V] voltage range, a reduction decomposition reaction highlights the Li-insertion/extraction behaviors, and low phase crystallinity is observed during cycling, in addition an excellent rate behavior and a reversible capacity of 250 mAhg - 1 can still be maintained after 50 cycles at high cycling rate 5C.« less

  15. Low temperature structural variations of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-7%BaTiO{sub 3} single crystal: Evidences from optical ellipsometry and Raman scattering

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

    Huang, T.; Guo, S.; Xu, L. P.

    2015-06-14

    Optical properties and structural variations of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-7%BaTiO{sub 3} (NBT-7%BT) single crystal have been studied by temperature-dependent optical ellipsometry and Raman spectroscopy from 4.2 to 300 K. The second derivative of the complex dielectric functions reveals two interband transitions (E{sub cp1} and E{sub cp2}) located at about 3.49 and 4.25 eV, respectively. Depending on the temperature evolution of electronic transitions, structural variations appear near 60, 150, and 240 K, respectively. These anomalies are also well illustrated from the low-frequency phonon modes involving vibrations of Bi. The low-temperature structural variations of NBT-7%BT crystal can be associated with instability of the crystalline latticemore » driven by off-centered Bi ions, followed by the variations of polarizability of the unit cells.« less

  16. [Properties of NiTi wires with direct electric resistance heat treatment method in three-point bending tests].

    PubMed

    Wang, Hong-mei; Wang, Bang-kang; Ren, Chao-chao; Bai, Yu-xing

    2011-03-01

    To investigate the mechanical properties of Ni-Ti wires with direct electric resistance heat treatment (DERHT) method in three-point bending tests. Two superelastic Ni-Ti wires (wire A: Smart SE, wire B: SENTALLOY SE, 0.406 mm × 0.559 mm) and 2 heat-actived Ni-Ti wires (wire C: Smart SM, wire D: L&H TITAN, 0.406 mm × 0.559 mm) were selected. They were heat-treated using the DERHT method by a controlled electric current (6.36 A) applied for different period of time [0 (control), 1.0, 1.5, 2.0, 2.5 seconds). Then, a three-point bending test was performed under controlled temperature (37°C) to examine the relationships between the deflection and the load in the bending of wires. After DERHT treatment, the plateau in the force-deflection curve of superelastic Ni-Ti wires and heat-activated Ni-Ti wires were increased. When the wires were heated for 2.0 seconds and deflected to 1.5 mm, the loading force of A, B, C and D Ni-Ti wires increased from (3.85 ± 0.11), (3.62 ± 0.07), (3.28 ± 0.09), (2.91 ± 0.23) N to (4.33 ± 0.07), (4.07 ± 0.05), (4.52 ± 0.08), (3.27 ± 0.15) N respectively. DERHT method is very convenient for clinical use. It is possible to change the arch form and superelastic force of NiTi wires. The longer the heating time is, the more the superelastic characteristics of the wires are altered.

  17. Experiments using a 200 kV implanter and a 5 MV tandem accelerator

    NASA Astrophysics Data System (ADS)

    Ishigami, Ryoya; Ito, Yoshifumi; Yasuda, Keisuke; Hatori, Satoshi

    2001-07-01

    N+ ions with an energy of 190 keV were implanted into an Al alloy (95% Al and 5% Mg) to a dose of 1.5×1019ions/cm2. A layer of AlN with 1.4 μm thickness was obtained. The amounts of InN deposited on GaAs or Al2O3 were measured by RBS using He2+ ions with an energy of 3.14 MeV generated by a tandem accelerator. The thickness was estimated to be 0.047 μm and 0.26 μm in each case. An experiment on transmission ERDA using He2+ ions with an energy of 15 MeV is proposed for the measurement of deuterons in thick Ti foil with good depth resolution.

  18. Synthesis and characterization of (Bi{sub 0.5}Ba{sub 0.5}) (Fe{sub 0.5}Ti{sub 0.5}) O{sub 3} ceramic

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

    Parida, B.N., E-mail: bichitra_mama@rediffmail.com; Das, Piyush R., E-mail: prdas63@gmail.com; Padhee, R.

    2015-01-15

    Graphical abstract: Temperature variation of (a) dielectric constant (b) dielectric loss of the sample. - Highlights: • The high values of dielectric permittivity and low value of tangent loss. • It used for microwave applications. • The impedance and dielectric relaxation in the material is non exponential and non Debye-type. • Its ac conductivity obeys Jonscher universal power law. - Abstract: The polycrystalline sample of (Bi{sub 0.5}Ba{sub 0.5}) (Fe{sub 0.5}Ti{sub 0.5}) O{sub 3} (BF–BT) was prepared by a standard mixed oxide method. Analysis of room temperature XRD pattern and Raman/FTIR spectra of the compound does not exhibit any change inmore » its crystal structure of BaTiO{sub 3} on addition of BiFeO{sub 3} in equal ratio. The surface morphology of the gold-plated sintered pellet sample recorded by SEM (scanning electron microscope) exhibits a uniform distribution of grains with less porosity. Detailed studies of nature and quantity of variation of dielectric constant, tangent loss, and polarization with temperature and frequency indicate the existence of ferroelectric phase transition at high-temperature. There is a low-temperature anti-ferromagnetic phase transition below 375 °C in the material. Detailed studies of electrical properties (impedance, modulus, etc.) of the material confirmed a strong correlation between micro-structure and properties.« less

  19. Production and mechanical properties of Ti-5Al-2.5Fe-xCu alloys for biomedical applications.

    PubMed

    Yamanoglu, Ridvan; Efendi, Erdinc; Kolayli, Fetiye; Uzuner, Huseyin; Daoud, Ismail

    2018-01-30

    In this study, the mechanical, antibacterial properties and cell toxicity response of Ti-5Al2.5Fe alloy with different copper contents were investigated. The alloys were prepared by high-energy ball milling using elemental Ti, Al, Fe, and Cu powders and consolidated by a uniaxial vacuum hot press. Staphylococcus aureus strain ATCC 29213 and Escherichia coli strain ATCC 25922 were used to determine the antibacterial properties of the sintered alloys. The in vitro cytotoxicity of the samples was evaluated with HeLa (ATTC, CCL-2) cells using thiazolyl blue tetrazolium bromide. The mechanical behavior of the samples was determined as a function of hardness and bending tests and analyzed by scanning electron microscopy, energy dispersive x-ray spectroscopy, optical microscopy and x-ray diffraction (XRD). The results showed that the Cu content significantly improved the antibacterial properties. Cu addition prevented the formation of E. coli and S. aureus colonies on the surface of the samples. All samples exhibited very good cell biocompatibility. The alloys with different copper contents showed different mechanical properties, and the results were correlated by microstructural and XRD analyses in detail. Our results showed that Cu has a great effect on the Ti5Al2.5Fe alloy and the alloy is suitable for biomedical applications with enhanced antibacterial activity.

  20. Characterization and mechanical properties investigation of TiN-Ag films onto Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Du, Dongxing; Liu, Daoxin; Zhang, Xiaohua; Tang, Jingang; Xiang, Dinggen

    2016-03-01

    To investigate their effect on fretting fatigue (FF) resistance of a Ti-6Al-4V alloy, hard solid lubricating composite films of TiN with varying silver contents (TiN-Ag) were deposited on a Ti-6Al-4V alloy using ion-assisted magnetron sputtering. The surface morphology and structure were analyzed by atomic force microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy. The hardness, bonding strength, and toughness of films were tested using a micro-hardness tester, scratch tester, and a repeated press-press test system that was manufactured in-house, respectively. The FF resistance of TiN-Ag composite films was studied using self-developed devices. The results show that the FF resistance of a titanium alloy can be improved by TiN-Ag composite films, which were fabricated using hard TiN coating doped with soft Ag. The FF life of Ag0.5, Ag2, Ag5, Ag10 and Ag20 composite films is 2.41, 3.18, 3.20, 2.94 and 2.87 times as great as that of the titanium alloy, respectively. This is because the composite films have the better toughness, friction lubrication, and high bonding strength. When the atomic fraction of Ag changes from 2% to 5%, the FF resistance of the composite films shows the best performance. This is attributed to the surface integrity of the composite film is sufficiently fine to prevent the initiation and early propagation of FF cracks.

  1. 44 CFR 63.5 - Coverage for contents removal.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program IMPLEMENTATION OF SECTION 1306(c) OF THE NATIONAL FLOOD INSURANCE ACT OF 1968 General § 63.5 Coverage for contents... the definition of “Direct Physical Loss by or from Flood” in the SFIP for the expense of removing...

  2. 44 CFR 63.5 - Coverage for contents removal.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program IMPLEMENTATION OF SECTION 1306(c) OF THE NATIONAL FLOOD INSURANCE ACT OF 1968 General § 63.5 Coverage for contents... the definition of “Direct Physical Loss by or from Flood” in the SFIP for the expense of removing...

  3. Selection of Compositions in Ti-Cr-C-Steel, Ti-B, Ti-B-Me Systems and Establishing Synthesis Parameters for Obtaining Product by “SHS-Electrical Rolling”

    NASA Astrophysics Data System (ADS)

    Aslamazashvili, Zurab; Tavadze, Giorgi; Chikhradze, Mikheil; Namicheishvili, Teimuraz; Melashvili, Zaqaria

    2017-12-01

    For the production materials by the proposed Self-propagating High-Temperature Synthesis (SHS) - Electric Rolling method, there are no limitations in the length of the material and the width only depends on the length of rolls. The innovation method enables to carry out the process in nonstop regime, which is possible by merging energy consuming SHS method and Electrical Rolling. For realizing the process it is mandatory and sufficient, that initial components, after initiation by thermal pulse, could interaction with the heat emission, which itself ensures the self-propagation of synthesis front in lieu of heat transfer in the whole sample. Just after that process, the rolls instantly start rotation with the set speed to ensure the motion of material. This speed should be equal to the speed of propagation of synthesis front. The synthesized product in hot plastic condition is delivered to the rolls in nonstop regime, simultaneously, providing the current in deformation zone in order to compensate the energy loses. As a result by using the innovation SHS -Electrical Rolling technology we obtain long dimensional metal-ceramic product. In the presented paper optimal compositions of SHS chasms were selected in Ti-Cr-C-Steel, Ti-B and Ti-B-Me systems. For the selection of the compounds the thermodynamic analysis has been carried out which enabled to determine adiabatic temperature of synthesis theoretically and to determine balanced concentrations of synthesized product at synthesis temperature. Thermodynamic analysis also gave possibility to determine optimal compositions of chasms and define the conditions, which are important for correct realization of synthesis process. For obtaining non porous materials and product by SHS-Electrical Rolling, it is necessary to select synthesis and compacting parameters correctly. These parameters are the pressure and the time. In Ti-Cr-C-Steel, Ti-B and Ti-B-Me systems the high quality (nonporous or low porosity <2%) of materials

  4. Low-Energy Amorphization of Ti1Sb2Te5 Phase Change Alloy Induced by TiTe2 Nano-Lamellae

    PubMed Central

    Ding, Keyuan; Rao, Feng; Lv, Shilong; Cheng, Yan; Wu, Liangcai; Song, Zhitang

    2016-01-01

    Increasing SET operation speed and reducing RESET operation energy have always been the innovation direction of phase change memory (PCM) technology. Here, we demonstrate that ∼87% and ∼42% reductions of RESET operation energy can be achieved on PCM cell based on stoichiometric Ti1Sb2Te5 alloy, compared with Ge2Sb2Te5 and non-stoichiometric Ti0.4Sb2Te3 based PCM cells at the same size, respectively. The Ti1Sb2Te5 based PCM cell also shows one order of magnitude faster SET operation speed compared to that of the Ge2Sb2Te5 based one. The enhancements may be caused by substantially increased concentration of TiTe2 nano-lamellae in crystalline Ti1Sb2Te5 phase. The highly electrical conduction and lowly thermal dissipation of the TiTe2 nano-lamellae play a major role in enhancing the thermal efficiency of the amorphization, prompting the low-energy RESET operation. Our work may inspire the interests to more thorough understanding and tailoring of the nature of the (TiTe2)n(Sb2Te3)m pseudobinary system which will be advantageous to realize high-speed and low-energy PCM applications. PMID:27469931

  5. Low-Energy Amorphization of Ti1Sb2Te5 Phase Change Alloy Induced by TiTe2 Nano-Lamellae.

    PubMed

    Ding, Keyuan; Rao, Feng; Lv, Shilong; Cheng, Yan; Wu, Liangcai; Song, Zhitang

    2016-07-29

    Increasing SET operation speed and reducing RESET operation energy have always been the innovation direction of phase change memory (PCM) technology. Here, we demonstrate that ∼87% and ∼42% reductions of RESET operation energy can be achieved on PCM cell based on stoichiometric Ti1Sb2Te5 alloy, compared with Ge2Sb2Te5 and non-stoichiometric Ti0.4Sb2Te3 based PCM cells at the same size, respectively. The Ti1Sb2Te5 based PCM cell also shows one order of magnitude faster SET operation speed compared to that of the Ge2Sb2Te5 based one. The enhancements may be caused by substantially increased concentration of TiTe2 nano-lamellae in crystalline Ti1Sb2Te5 phase. The highly electrical conduction and lowly thermal dissipation of the TiTe2 nano-lamellae play a major role in enhancing the thermal efficiency of the amorphization, prompting the low-energy RESET operation. Our work may inspire the interests to more thorough understanding and tailoring of the nature of the (TiTe2)n(Sb2Te3)m pseudobinary system which will be advantageous to realize high-speed and low-energy PCM applications.

  6. Ion-irradiation resistance of the orthorhombic Ln2TiO5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) series

    NASA Astrophysics Data System (ADS)

    Aughterson, Robert D.; Lumpkin, Gregory R.; Ionescu, Mihail; Reyes, Massey de los; Gault, Baptiste; Whittle, Karl R.; Smith, Katherine L.; Cairney, Julie M.

    2015-12-01

    The response of Ln2TiO5 (where Ln is a lanthanide) compounds exposed to high-energy ions was used to test their suitability for nuclear-based applications, under two different but complementary conditions. Eight samples with nominal stoichiometry Ln2TiO5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy), of orthorhombic (Pnma) structure were irradiated, at various temperatures, with 1 MeV Kr2+ ions in-situ within a transmission electron microscope. In each case, the fluence was increased until a phase transition from crystalline to amorphous was observed, termed critical dose Dc. At certain elevated temperatures, the crystallinity was maintained irrespective of fluence. The critical temperature for maintaining crystallinity, Tc, varied non-uniformly across the series. The Tc was consistently high for La, Pr, Nd and Sm2TiO5 before sequential improvement from Eu to Dy2TiO5 with Tc's dropping from 974 K to 712 K. In addition, bulk Dy2TiO5 was irradiated with 12 MeV Au+ ions at 300 K, 723 K and 823 K and monitored via grazing-incidence X-ray diffraction (GIXRD). At 300 K, only amorphisation is observed, with no transition to other structures, whilst at higher temperatures, specimens retained their original structure. The improved radiation tolerance of compounds containing smaller lanthanides has previously been attributed to their ability to form radiation-induced phase transitions. No such transitions were observed here.

  7. Effect of heat stress on brain 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in some vertebrate species.

    PubMed

    Mohamed, M I; Rahman, T A

    1982-01-01

    1. The variations in 5-HT and 5-HIAA levels following heat exposure and split heat doses were determined in the different brain regions of Gerbillus pyramidum, Streptopelia senegalensis aegyptiaca and Agama stellio. 2. Heat exposure was found to be associated with an increase in the levels of the two indole compounds. 3. The 5-HT concentrations increased markedly in the three species following the first heat dose and decreased following the second dose in the various brain regions except in the cerebellum of Agama. 4. The increased 5-HT levels when animals are exposed to high temperature probably represent a response to activate heat-loss mechanisms and to depress heat production.

  8. 46 CFR 56.85-5 - Heating and cooling method.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Heating and cooling method. 56.85-5 Section 56.85-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Heat Treatment of Welds § 56.85-5 Heating and cooling method. Heat treatment may be accomplished...

  9. 46 CFR 56.85-5 - Heating and cooling method.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Heating and cooling method. 56.85-5 Section 56.85-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Heat Treatment of Welds § 56.85-5 Heating and cooling method. Heat treatment may be accomplished...

  10. 46 CFR 56.85-5 - Heating and cooling method.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Heating and cooling method. 56.85-5 Section 56.85-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Heat Treatment of Welds § 56.85-5 Heating and cooling method. Heat treatment may be accomplished...

  11. 46 CFR 56.85-5 - Heating and cooling method.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Heating and cooling method. 56.85-5 Section 56.85-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Heat Treatment of Welds § 56.85-5 Heating and cooling method. Heat treatment may be accomplished...

  12. 46 CFR 56.85-5 - Heating and cooling method.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Heating and cooling method. 56.85-5 Section 56.85-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Heat Treatment of Welds § 56.85-5 Heating and cooling method. Heat treatment may be accomplished...

  13. Numerical simulation of temperature distribution in cylindrical ilmenite (FeTiO3) due to microwave heating

    NASA Astrophysics Data System (ADS)

    Hidayat, Mas Irfan P.; Fellicia, Dian Mughni; Rafandi, Ferdiansyah Iqbal

    2018-04-01

    Microwave assisted heating has been extensively used in materials processing particularly in extraction of TiO2 from Ilmenite (FeTiO3) minerals. Nevertheless, this method could generate non-uniform temperature distribution during the heating process. The observation of this phenomena in cylindrical ilmenite has been conducted by numerical simulation using finite element method according to the Poynthing's theorem. Four different cylinders with variation on its height were simulated in ANSYS 17 with input microwave power of 5.5 Kw. The results indicated that height of heated object could vigorously influence the uniformity of temperature inside the body.

  14. Microstructure and Oxidation of (La,Sr)CrO3-Added Ti3SiC2 Composites.

    PubMed

    Lee, Dong Bok

    2015-11-01

    Composites of Ti3SiC2-(10, 20, 40)wt% La0.8Sr0.2CrO3 were synthesized by hot pressing powders of Ti3SiC2 and La0.8Sr0.2CrO3. These powders reacted to form stable TiC carbides and LaTiO3, Cr2Ti4O11, La2O3, and SrCrO4 oxides during hot pressing. The composites consisted primarily of a fine TiC-rich matrix phase and coarse Ti3SiC2 dispersoids. The addition of oxidation-immune La0.8Sr0.2CrO3 into Ti3SiC2 increased the oxidation rate because TiC formed during hot pressing. During oxidation of the composites at 800-1000 degrees C for 100 h in air, Ti diffused outward to form an outer rutile-TiO2 layer, and oxygen transported inward to form an inner oxide layer.

  15. Low Temperature Superplasticity of Ti-6Al-4V Processed by Warm Multidirectional Forging (Preprint)

    DTIC Science & Technology

    2012-07-01

    microstructure in the two-phase titanium alloy Ti- 6Al - 4V . A microstructure with a grain size of 135 nm was attained, enabling low-temperature...the / titanium alloy Ti- 6Al - 4V [3]. The great interest in microstructure refinement is associated with significantly reduced superplastic (SP...consisted of the / titanium alloy Ti- 6Al - 4V with a nominal composition (in weight pct.) of 6.3 Al, 4.1 V, 0.18 Fe, 0.03 Si, 0.02 Zr, 0.01 C, 0.18 O, 0.01 N

  16. Nanostructured and Conventional Cr2O3, TiO2, and TiO2-Cr2O3 Thermal-Sprayed Coatings for Metal-Seated Ball Valve Applications in Hydrometallurgy

    NASA Astrophysics Data System (ADS)

    Vernhes, Luc; Bekins, Craig; Lourdel, Nicolas; Poirier, Dominique; Lima, Rogerio S.; Li, Duanjie; Klemberg-Sapieha, Jolanta E.

    2016-06-01

    A detailed characterization project was undertaken by Velan, an international industrial valve designer and manufacturer, in collaboration with the National Research Council of Canada, Boucherville, and Polytechnique Montréal. The purpose was to assess the mechanical and tribological resistances of promising ceramic coatings for hydrometallurgy applications, including a novel n-TiO2-Cr2O3 blend. Hardness and shear strength were determined using microhardness indentation testers and universal tensile testing equipment. Wear resistance of the coatings under sliding wear, abrasion, and galling conditions were measured by standard pin-on-disk tests, abrasion tests, and custom-designed galling tests. The main result is that the synergy between Cr2O3 and n-TiO2 produced abrasion performance exceeding that of these materials alone. Also, an optimized balance between the hard and brittle Cr2O3 phases and the soft and ductile n-TiO2 phases resulted in higher abrasion, sliding, and galling resistance. The novel n-TiO2-Cr2O3 blend is therefore considered as a promising evolution of the current TiO2-Cr2O3 blend.

  17. Materials Characterization of Electron Beam Melted Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Draper, Susan; Lerch, Brad; Rogers, Richard; Martin, Richard; Locci, Ivan; Garg, Anita

    2015-01-01

    An in-depth material characterization of Electron Beam Melted (EBM) Ti-6Al-4V material has been completed. Hot Isostatic Pressing (HIP) was utilized to close porosity from fabrication and also served as a material heat treatment to obtain the desired microstructure. The changes in the microstructure and chemistry from the powder to pre-HIP and post-HIP material have been analyzed. Computed tomography (CT) scans indicated porosity closure during HIP and high-density inclusions scattered throughout the specimens. The results of tensile and high cycle fatigue (HCF) testing are compared to conventional Ti-6Al-4V. The EBM Ti-6Al-4V had similar or superior mechanical properties compared to conventionally manufactured Ti-6Al-4V.

  18. The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

    NASA Technical Reports Server (NTRS)

    Schuon, S. R.

    1982-01-01

    The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life.

  19. 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.

  20. Synthesis of Ti-6Al-4V alloy with nano-TiN microstructure via spark plasma sintering technique

    NASA Astrophysics Data System (ADS)

    E Falodun, O.; Obadele, B. A.; Oke, S. R.; E Maja, M.; Olubambi, P. A.

    2017-12-01

    The effect of nano-TiN dispersion strengthened Ti-6Al-4V via spark plasma sintering method has been investigated. Ti-6Al-4V with 4 vol. percent of nano-TiN were mixed in a Turbula shaker mixer for 8 h at a speed of 49 rpm and the admixed powders were sintered at sintering temperature range of 1000 - 1100 °C, holding time of 10-30 mins, heating rate of 100 °C/min under an applied pressure of 50 MPa. The morphology of the as-received and sintered compacts was examined by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and phase analysis was done by X-ray diffractometry (XRD). The sintered compacts without nano-TiN reveal lamellar structure while reinforced Ti-6Al-4V with nano-TiN shows a bimodal structure and titanium nitride has a great influence on a grain growth at high temperature. Furthermore, the microstructural formation mechanism was investigated. With the addition of the content of Ti-6Al-4V with 4 vol.% of nano-TiN, the micro-hardness also improved and this was due to homogenous distribution of TiN in Ti-6Al-4V matrix.