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Sample records for rastvorov karbidov ti

  1. PIIID-formed (Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti coatings on NiTi shape memory alloy for medical applications.

    PubMed

    Sun, Tao; Wang, Lang-Ping; Wang, Min; Tong, Ho-Wang; Lu, William W

    2012-08-01

    (Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti composite coatings were fabricated on NiTi shape memory alloy via plasma immersion ion implantation and deposition (PIIID). Surface morphology of samples was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Cross-sectional morphology indicated that the PIIID-formed coatings were dense and uniform. X-ray diffraction (XRD) was used to characterize the phase composition of samples. X-ray photoelectron spectroscopy (XPS) results showed that the surface of coated NiTi SMA samples was Ni-free. Nanoindentation measurements and pin-on-disc tests were carried out to evaluate mechanical properties and wear resistance of coated NiTi SMA, respectively. For the in vitro biological assessment of the composite coatings in terms of cell morphology and cell viability, osteoblast-like SaOS-2 cells and breast cancer MCF-7 cells were cultured on NiTi SMA samples, respectively. SaOS-2 cells attached and spread better on coated NiTi SMA. Viability of MCF-7 cells showed that the PIIID-formed composite coatings were noncytotoxic and coated samples were more biocompatible than uncoated samples. PMID:24364947

  2. Tribological behavior and wear mechanisms of TiN/TiCN/TiN multilayer coatings

    SciTech Connect

    Su, Y.L.; Kao, W.H.

    1998-10-01

    This work employs the PVD process to deposit coatings of single layer TiN, binary layer TiN/TiCN, multilayer TiN/Ti/TiN, and sequenced TiN/TiCN/TiN multilayer coatings with variable individual TiN-layer and TiCN-layer thicknesses on tungsten carbide disks and inserts. Also investigated are the fracture mechanisms and the influence of sequence and thickness of these coatings on cylinder-on-disk, line-contact wear mode and ball-on-disk, point-contact wear mode through SRV reciprocating wear tests. Actual milling tests identify wear performance. Experimental results indicate that the coating with a total thickness of 7 {micro}m and layer sequence TiN/TiCN/TiN exhibits good wear resistance on SRV wear test and milling test. The thickest multilayer TiN/Ti/TiN coating, although having the highest hardness, has the worst wear resistance for all tests. Notably zero-wear performance was observed for all coating disks under cutting fluid lubricated condition due to the transferred layers formed between the contact interface.

  3. Dissolution rate measurements of TiN in Ti-6242

    SciTech Connect

    Bewlay, B.P.; Gigliotti, M.F.X.

    1997-01-01

    This paper describes measurements of the dissolution rate of nitrided Ti sponge and monolithic TiN rod in molten Ti-6242. The dissolution rate is described in terms of an interface recession rate that was 2.2 {micro}m/s for a Ti-6242 temperature of 1,725 C and dissolution times between 1 and 100 min. Similar dissolution rates were measured for nitrided sponge and monolithic rod. This report also descries the microstructural and chemical interdiffusion phenomena that occur during dissolution of solid {delta}TiN in molten Ti-6242. There is a N-containing solid {alpha}Ti layer and a N-solidified {beta}Ti layer between the solid {delta}TiN and liquid Ti-6242 during dissolution. Microprobe measurements indicate that diffusion of Al, Zr, Sn and Mo into {delta}TiN did not occur. Steep N concentration profiles were observed in the {alpha}Ti layer. Al, Zr, Sn and Mo were observed in the N-solidified {beta}Ti layer contained <1% N. Similar microstructural and interdiffusional behaviors were observed during dissolution of nitrided sponge and monolithic {delta}TiN rod in molten Ti-6242.

  4. In situ NiTi/Nb(Ti) composite

    SciTech Connect

    Jiang, Daqiang Cui, Lishan; Jiang, Jiang; Zheng, Yanjun

    2013-12-15

    Graphical abstract: - Highlights: • In situ NiTi/Nb(Ti) composites were fabricated. • The transformation temperature was affected by the mixing Ti:Ni atomic ratios. • The NiTi component became micron-scale lamella after forging and rolling. • The composite exhibited high strength and high damping capacity. - Abstract: This paper reports on the creation of a series of in situ NiTi/Nb(Ti) composites with controllable transformation temperatures based on the pseudo-binary hypereutectic transformation of NiTi–Nb system. The composite constituent morphology was controlled by forging and rolling. It is found that the thickness of the NiTi lamella in the composite reached micron level after the hot-forging and cold-rolling. The NiTi/Nb(Ti) composite exhibited high damping capacity as well as high yield strength.

  5. Ti-TiC-TiC/DLC gradient nano-composite film on a biomedical NiTi alloy.

    PubMed

    Zheng, Yufeng; Liu, Dong; Liu, Xiliang; Li, Li

    2008-12-01

    Ti-TiC-TiC/diamond-like carbon (DLC) gradient nano-composite films have been prepared on NiTi alloy substrates by the technique of plasma immersion ion implantation and deposition (PIIID) combined with plasma-enhanced chemical vapor deposition (PECVD). The influence of negative bias voltage applied to the substrate (from -100 V to -500 V) on the chemical structure, microstructure, mechanical properties and corrosion resistance was investigated by Raman spectrum, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), x-ray diffraction (XRD), friction coefficient test, scratch test, nano-indentation test and anodic polarization experiments. The Raman spectrum and XPS results showed that the doped films kept an amorphous DLC structure. TEM observation revealed that nanometer TiC particles were surrounded by the amorphous DLC. With the increase of bias voltage, the ratio of sp(2)/sp(3) first decreased, reaching a minimum value at -200 V, and then increased. The nano-indentation results showed that the hardness of the Ti-TiC-TiC/DLC gradient films reached the maximum value at -200 V when TiC particles reached the maximum content in the films. The friction coefficient test and scratch test indicated that Ti-TiC-TiC/DLC gradient films had a low friction coefficient and high bonding strength with the NiTi substrates. Combined with anodic polarization curves and SEM observation, it was found that the corrosion resistance of the Ti-TiC-TiC/DLC gradient films was much better than that of the bare NiTi alloy. PMID:19029600

  6. Ti Diffusion in Zircon

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.; Watson, E. B.

    2006-12-01

    Diffusion of Ti under anhydrous conditions at 1 atmosphere and under fluid-present conditions at 1.1-1.2 GPa has been measured in natural zircon. The source of diffusant for 1-atm experiments was a ZrO2- TiO2-ZrSiO4 mixture, with experiments run in Pt capsules. Diffusion experiments conducted in the presence of H2O-CO2 fluid were run in a piston-cylinder apparatus, using a source of ground TiO2, ZrSiO4 and SiO2, with oxalic acid added to produce H2O-CO2 vapor and partially melt the solid source material, yielding an assemblage of rutile + zircon + melt + vapor. Resonant nuclear reaction analysis (NRA) with the nuclear reaction ^{48}Ti(p,Γ)^{49}V was used to measure diffusion profiles for both sets of experiments. The following Arrhenius relation was obtained for Ti diffusion normal to c over the temperature range 1350-1550C at one atmosphere: DTi = 3.3x102 exp(-754 ± 56 kJ mol-1 /RT) m2sec-1 Ti diffusivities were found to be similar for experiments run under fluid-present conditions. A fit to all of the data yields the Arrhenius relation D = 1.3x103 exp(-741 ± 46 kJ mol-1 /RT) m2sec-1. These data suggest that zircon should be extremely retentive of Ti chemical signatures, indicating that the recently developed Ti-in-zircon crystallization geothermometer (Watson and Harrison, 2005; Watson et al., 2006) will be quite robust in preserving temperatures of zircon crystallization. Titanium diffuses somewhat faster in zircon than larger tetravalent cations U, Th, and Hf, but considerably more slowly than Pb, the REE, and oxygen; hence Ti crystallization temperatures may be retained under circumstances when radiometric ages or other types of geochemical information are lost. Watson EB, Harrison TM (2005) Science 308, 841-844. Watson EB, Wark DA, Thomas JB (2006) CMP(in press).

  7. Hydrogen storage in Ti-TiO2 multilayers

    NASA Astrophysics Data System (ADS)

    Tarnawski, Z.; Kim-Ngan, Nhu-T. H.; Zakrzewska, K.; Drogowska, K.; Brudnik, A.; Balogh, A. G.; Kužel, R.; Havela, L.; Sechovsky, V.

    2013-06-01

    Multilayered thin films of Ti-TiO2 system have been investigated, focusing on all of the important parameters in both photocatalysis and H storage. Numerous Ti-TiO2 thin films with a single-, bi- and tri-layered structure have been deposited on different substrates by means of dc pulsed magnetron sputtering from a metallic Ti target in an inert Ar or reactive Ar + O2 atmosphere. The film chemical composition, depth profile, layer thickness and structure were determined by combined analysis of x-ray diffraction, x-ray reflectometry, Rutherford back- scattering and optical reflectivity spectra. The results show that the Ti films deposited on Si(111) exhibit a strong preferred orientation with the (00.1) plane parallel to the substrate, while a columnar structure was developed for TiO2 films. H charging at 1 bar and at 300 °C revealed that, in the case of the tri-layered structure of Ti/TiO2/Ti/Si(111), H diffused through the TiO2 layer without any accumulation in it. Pd acts as a catalyst for gathering H in Ti layers and up to 50% of H is stored in the topmost and bottom Ti layers. The preferential orientation in the Ti films was found to be destroyed upon hydrogenation at 100 bar. The hydride TiHx phase (x < 0.66) was formed under such a high H pressure. Invited talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology IWAMSN2012, 30 October - 2 November, 2012, Ha Long, Vietnam.

  8. Ti site occupancy in zircon

    NASA Astrophysics Data System (ADS)

    Tailby, N. D.; Walker, A. M.; Berry, A. J.; Hermann, J.; Evans, K. A.; Mavrogenes, J. A.; O'Neill, H. St. C.; Rodina, I. S.; Soldatov, A. V.; Rubatto, D.; Sutton, S. R.

    2011-02-01

    Ti site occupancy in zircon (ZrSiO 4) is fundamental to thermobarometry because substitution mechanisms control Ti content-temperature relations. Here we describe the results of three independent methods used to demonstrate that Ti substitutes for Si and not Zr in zircon. Zircon grains were synthesized from oxide powders held in a Na 2WO 4 flux at 1 bar and 1300 °C. Zircon grains equilibrated with rutile + cristobalite show Ti contents (1201 ppm) nearly half that of zircon grains equilibrated with srilankite ((Ti,Zr)O 2) + tetragonal zirconia (2640 ppm). The lower Ti content of zircon grains produced at silica-saturated conditions indicates that Ti substitution predominately occurs on the Si site. Moreover, the higher Ti contents of silica-saturated experiments at 1 bar (1201 ppm), relative to those at 1 GPa (457 ppm, Ferry and Watson, 2007), indicates a substantial pressure effect on Ti solubility in zircon. Measured Ti K-α edge X-ray Absorption Near Edge Structure (XANES) spectra of synthetic zircon grains show energies and normalized intensities akin to those seen among tetrahedrally coordinated Ti-bearing standard minerals, strongly suggesting that Ti occupies the Si site. Density functional theory (DFT) calculations confirm that Ti substitution is most likely to occur on the Si site and predict a Ti-O bond length of 1.797 Å (compared to an average of 2.160 Å for substitution on the Zr site), in excellent agreement with X-ray Absorption Fine Structure (EXAFS) spectra of experimentally grown zircon grains which indicate a value of 1.76(1) Å. The software FEFF 8.4 was used to simulate XANES spectra from the defect structures determined by DFT for Ti substituting on both the Si and Zr sites. The predicted spectrum for Ti on the Si site reproduces all the key features of the experimental zircon spectra, whereas Ti on the Zr site is markedly different. All applied methods confirm that Ti substitutes for Si in zircon. Consequently, the Ti content of zircon at a

  9. TI-73 Calculator Activities

    ERIC Educational Resources Information Center

    Phillips-Bey, Carol K.

    2004-01-01

    This article describes TI-73 calculator activities appropriate for middle school students. It was found that the use of the calculator allowed for higher-level thinking and a richer exploration of mathematical ideas by students. [Included with this article are "Dice Roll Worksheet" and "Transforming Tree Worksheet".] (Contains 9 figures.)

  10. Electronic Structure of Ti substituted hydroxyapatite: TiHap

    NASA Astrophysics Data System (ADS)

    Yin, Shuxia; Ellis, Donald

    2009-03-01

    Hydroxyapatite (Hap), with the chemical formula Ca10(PO4)6(OH)2, is the main mineral constituent of mammal tooth enamel and bone and has become an important biomaterial with medical applications. Hap also attracts increasing interest for use in environmental adsorbents and catalysts due to its porous nature and highly active ion-exchange character. Ti-modified Hap (TiHap) has been proved to possess high affinity to organic molecules and bacteria as well as high photocatalytic activity for their oxidative decomposition. The concentration of Ti^4+ is a key factor controlling TiHap crystallinity and catalytic efficiency. Here we studied the sorption mechanism of Ti^4+ on Hap using Density Functional Theory within periodic slab models. Ti^4+ or (Ti(OH)2)^2+, as the most likely ion exchange species with Ca^2+, were first considered in bulk Hap. A second charge compensated model considered includes both surface Ca ion vacancies and substitutional Ti^4+. To obtain insight of the energetic stability and microscopic crystal structure of TiHap, Ti substitution on different Ca sites and distributions at different atomic ratios are investigated in both bulk and surface models.

  11. Ti Diffusion in Pyroxene

    NASA Astrophysics Data System (ADS)

    Cherniak, D.; Liang, Y.

    2008-12-01

    Diffusion of titanium has been characterized in natural enstatite and diopside under buffered conditions and in air. The sources of diffusant for the enstatite experiments were mixtures of Mg, Si and Ti oxide powders, which were combined and heated at 1300°C overnight, and then thoroughly mixed with synthesized enstatite powder and heated for an additional day at 1300°C. Sources for diopside experiments were prepared similarly, using Ca, Mg, Si, and Ti oxide powders combined with synthesized diopside powder, with heating of source materials at 1200°C. Buffered experiments were prepared by enclosing source material and pyroxene (polished and pre-annealed under conditions comparable to those to be experienced in the experiment) in AgPd or platinum capsules, placing the metal capsule in a silica glass capsule with a solid buffer (to buffer at NNO or IW) and sealing the assembly under vacuum. Some experiments on enstatite were run in air; sample and source were placed in Pt capsules and crimped shut. Prepared capsules were then annealed in 1 atm furnaces for times ranging from 8 hours to a few months, at temperatures from 950 to 1200°C. The Ti distributions in the pyroxene were profiled with Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for Ti diffusion in a natural enstatite, for diffusion normal to the (210) cleavage face (950 - 1150°C, experiments run in air): DTi = 1.9×10-10 exp(-300 ± 44 kJ mol-1/RT) m2 sec-1. Diffusion under NNO and IW-buffered conditions is similar to that for experiments run in air, suggesting little dependence of Ti diffusion on oxygen fugacity. There is also little evidence of anisotropy, as diffusion normal to (001) does not differ significantly from diffusion for the other orientation. Preliminary findings for Ti diffusion in diopside suggest diffusivities similar to those for enstatite. Ti diffusivities in enstatite are similar to those of the trivalent REEs (Cherniak and Liang, 2007

  12. Complementary resistive switching of annealed Ti/Cu2O/Ti stacks

    NASA Astrophysics Data System (ADS)

    Wang, Hao-Yu; Jou, Shyankay; Huang, Bohr-Ran; Song, Wan-Jhen; Mao, Tzu-Zing

    2016-04-01

    Ti/Cu2O/Ti stacks with 25-nm-thick Cu2O layers were produced by sputter deposition and lift-off processes utilizing three photolithographic masks. Subsequent annealing of the Ti/Cu2O/Ti stacks at 250 °C in a vacuum induced interfacial reactions between the Ti and Cu2O layers and converted the Ti/Cu2O/Ti stacks to a Ti/TiO x /Cu/TiO x /Ti structure. This pentalayered stack resembled a pair of antiserial Ti/TiO x /Cu and Cu/TiO x /Ti resistive switching devices and, therefore, demonstrated complementary resistive switching behaviors.

  13. Reactive Ni/Ti nanolaminates

    SciTech Connect

    Adams, D. P.; Bai, M. M.; Rodriguez, M. A.; McDonald, J. P.; Jones, E. Jr.; Brewer, L.; Moore, J. J.

    2009-11-01

    Nickel/titanium nanolaminates fabricated by sputter deposition exhibited rapid, high-temperature synthesis. When heated locally, self-sustained reactions were produced in freestanding Ni/Ti multilayer foils characterized by average propagation speeds between approx0.1 and 1.4 m/s. The speed of a propagating reaction front was affected by total foil thickness and bilayer thickness (layer periodicity). In contrast to previous work with compacted Ni-Ti powders, no preheating of Ni/Ti foils was required to maintain self-propagating reactions. High-temperature synthesis was also stimulated by rapid global heating demonstrating low ignition temperatures (T{sub ig})approx300-400 deg. C for nanolaminates. Ignition temperature was influenced by bilayer thickness with more coarse laminate designs exhibiting increased T{sub ig}. Foils reacted in a vacuum apparatus developed either as single-phase B2 cubic NiTi (austenite) or as a mixed-phase structure that was composed of monoclinic B19{sup '} NiTi (martensite), hexagonal NiTi{sub 2}, and B2 NiTi. Single-phase, cubic B2 NiTi generally formed when the initial bilayer thickness was made small.

  14. Crystallographic Structure of Ti-6Al-4V, Ti-HP and Ti-CP Under High Pressure

    SciTech Connect

    Halevy, I.; Zamir, G; Winterrose, M; Ghose, S; Grandini, C; Moreno-Gobbi, A

    2010-01-01

    The phase stability of a commercial purity (Ti-CP), high purity (Ti-HP) and Ti-6Al-4V alloy were investigated in a diamond anvil cell up to 32 GPa and 298 K using a polychromatic X-ray beam. The Ti-CP and Ti-HP shown the same HCP (c/a {approx} 0.632) to Hexagonal (c/a {approx} 1.63) non reversible martensitic transition at about 9 GPa. The as received Ti-6Al-4V shows a very low relative volume fraction {beta}-Ti/{alpha}-Ti. No phase changes were observed in the Ti-6Al-4V alloy in the pressure range of this study. The {alpha} phase of the Ti-6Al-4V shows monotonic volume cell pressure dependence. This volume change is reversible and non-hysteretic. The cell of the a phase recovered its original volume when the pressure was released.

  15. Microstructure and Properties of (TiB2 + NiTi)/Ti Composite Coating Fabricated by Laser Cladding

    NASA Astrophysics Data System (ADS)

    Lin, Yinghua; Lei, Yongping; Fu, Hanguang; Lin, Jian

    2015-10-01

    Agglomerated TiB2 particle and network-like structure-reinforced titanium matrix composite coatings were prepared by laser cladding of the Ni + TiB2 + Ti preplaced powders on Ti-6Al-4V alloy. The network-like structure mainly consisted of NiTi and Ni3Ti. Through the experiment, it was found that the size of agglomerated particle gradually decreased with the increase of Ti content, but the number of the network-like structure first increased and then disappeared. In-situ reaction competition mechanism and the formation of network-like structure were discussed. The average micro-hardness gradually decreased with the increase of Ti content, but the average fracture toughness gradually increased. Meanwhile, the wear resistance of the coatings is higher than that of the substrate, but the wear loss of the coatings is gradually increased with the increase of Ti content.

  16. Electronic Conduction in Ti/Poly-TiO2/Ti Structures

    NASA Astrophysics Data System (ADS)

    Hossein-Babaei, Faramarz; Alaei-Sheini, Navid

    2016-07-01

    Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2‑x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 106 V.m‑1 higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets.

  17. Electronic Conduction in Ti/Poly-TiO2/Ti Structures.

    PubMed

    Hossein-Babaei, Faramarz; Alaei-Sheini, Navid

    2016-01-01

    Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2-x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 10(6) V.m(-1); higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets. PMID:27404085

  18. Electronic Conduction in Ti/Poly-TiO2/Ti Structures

    PubMed Central

    Hossein-Babaei, Faramarz; Alaei-Sheini, Navid

    2016-01-01

    Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2−x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 106 V.m−1; higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets. PMID:27404085

  19. Microscopic Morphology and Microstructure of Ti-N and Ti-Ni Phase Between the Dilution Zone and the Clad Zone in Laser Remelting NiCrBSi/TiN Layer on Ti-6Al-4V Alloy Surface

    NASA Astrophysics Data System (ADS)

    Liu, Rongxiang; Guo, Lixin; Lei, Tingquan

    The microscopic morphology and microstructure of Ti-N and Ti-Ni phase between the dilution zone and the clad zone in laser remelting NiCrBSi/TiN layer on a Ti-6Al-4V alloy were characterized using TEM and SEM. The experimental results showed that during laser irradiation heating, TiN particles were partially dissolved into the melted Ni-base alloy, and the dissolved Ti and N atoms were precipitated in the form of TiN, TiN0.3. Ti exhibits height activity, it combines with Ni forming Ti2Ni, TiNi matrix intermetallic during laser remelting, faults exist in the Ti2Ni and TiNi phase, and crystal lattice of TiNi phase is superlattice. Lastly, the cause of the formation of the Ti-N and Ti-Ni phase is discussed.

  20. Characterization of a rapid thermal anneal TiNxOy/TiSi2 contact barrier

    NASA Astrophysics Data System (ADS)

    Ho, V. Q.

    1989-07-01

    In this paper, the physical and electrical properties of a TiNxOy/TiSi2 dual layer contact barrier are reported. The TiNxOy/TiSi2 barrier was formed by rapidly annealing a Ti thin film on Si in an N2 ambient. During this process, the Ti film surface reacts with N2 to form a TiNxOy skin layer and the bulk of the Ti film reacts with Si to form an underlying TiSi2 layer. The influences of rapid thermal anneal (RTA) conditions on the TiNxOy layer were investigated by varying the RTA temperature from 600 to 1100° C and cycle duration from 30 to 100 s. It is found that the resulting TiNxOy and TiSi2 layer thicknesses are dependent on RTA temperature and the starting Ti thickness. For a starting Ti thickness of 500Å, 150Å thick TiNxOy and 800Å thick TiSi2 are obtained after an RTA at 900° C for 30 s. The TiNxOy thickness is limited by a fast diffusion of Si into Ti to form TiSi2. When a Ti film is deposited on SiO2, Ti starts to react with SiO2 from 600° C and a significant reduction of the SiO2 thickness is observed after an RTA at 900° C. The resulting layer is composed of a surface TiNxOy layer followed by a complex layer of titanium oxide and titanium suicide. In addition, when Ti is depos-ited on TiSi2, thicker TiNxOy and TiSi2 layers are obtained after RTA. This is because the TiSi2 layer retards the diffusion of Si from the underlying substrate into the Ti layer. NMOSFETs were fabricated using the TiNxOy/TiSi2 as a contact barrier formed by RTA at 900° C for 30 s and a significant reduction of contact resistance was obtained. In addition, electromigration test at a high current density indicated that a significant improvement in mean time to failure (MTF) has been obtained with the barrier.

  1. Microstructural evolution and wear behaviors of laser cladding Ti2Ni/α(Ti) dual-phase coating reinforced by TiB and TiC

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The Ti2Ni/α(Ti) dual-phase coating reinforced by TiB and TiC was fabricated on the Ti6Al4V substrate by laser cladding. Phase constituents were confirmed by a theoretical prediction combined with X-ray diffraction (XRD) analyses. From the surface to the bottom of the coating, a regular evolution of the reinforcements' microstructure, namely TiCp+(TiB+TiC)e, (TiB+TiC)e and TiBp+(TiB+TiC)e (p and e were the abbreviations of primary and eutectic, respectively), was investigated by scanning electron microscopy (SEM). The coating possessed the higher microhardness than that of the substrate. An in situ dynamic method (in situ continuing tests at different time intervals) was designed to reveal wear behaviors at different wear stages. A quantitative calculation formula was established by a mathematic model to predict wear losses under different sliding time and applied loads in a definite precision. The wear mechanism was transformed from brittle debonding (at 10 N) to the joint action of brittle debonding and micro-cutting (at 20 N and 30 N) due to the microstructural evolution across the depth from the surface of the coating.

  2. LASE Ti: Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Mr. Leroy F. Matthews (Lockheed Engineering & Sciences Co.) is connecting the Thermal Control Unit cables in preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for integration into a NASA/ER-2 aircraft for a field mission. LASE is the first fully-engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150 mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE. Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  3. LASE Ti: Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Messrs. Leroy F. Matthews (left) and Frank J. Novak (Lockheed Engineering & Sciences Co.) are preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for integration into a NASA/ER-2 aircraft for a field mission. LASE is the first fully- engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150 mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE. Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instrument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  4. Emergence and coupling of topological surface states in tunable TI-non TI heterostructures

    NASA Astrophysics Data System (ADS)

    Koirala, Nikesh; Brahlek, Matthew; Liu, Jianpeng; Salehi, Maryam; Yusufaly, Tahir; Vanderbilt, David; Oh, Seongshik

    2015-03-01

    The most distinctive feature of topological insulators (TI) is the topologically protected surface states (TSS) that reside at the interface between TI and trivial insulators (non-TI). These TSS have been difficult to probe with transport measurements so far due to deleterious bulk conduction. Using atomically engineered TI - non TI heterostructures, we have studied the emergence and coupling of TSS at TI-non TI interfaces by tuning the thickness and transparency of the non-TI layer. Theoretical analysis based on first principle calculations as well as tunneling model are fully consistent with the observed experimental results and altogether provide a coherent picture of evolution of TSS at TI - non TI interface in such tunable heterostrucutres. Being near ideal systems for tuning TSS and allowing them to be probed via transport measurement such heterostructures open will new avenues for future research and applications.

  5. TI-83 Graphing Calculator Keystroke Guide.

    ERIC Educational Resources Information Center

    Panik, Cathy

    This document presents keystrokes for the Texas Instrument (TI-83) graphing calculator. After presenting some basic TI-83 keystrokes, activities for student practice are listed. This is followed by keystrokes for TI-83 advanced functions such as evaluating function values, finding the zero of a function, finding the intersection of two graphs,…

  6. Microstructure and corrosion resistance of TC2 Ti alloy by laser cladding with Ti/TiC/TiB2 powders

    NASA Astrophysics Data System (ADS)

    Diao, Yunhua; Zhang, Kemin

    2015-10-01

    In the present work, a TiC/TiB2 composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB2 powders. The surface microstructure, phase components and compositions were characterized with methods of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersive spectrometry (EDS). The cladding layer is consisted of Ti, TiC and TiB2. And the surface microhardness was measured. After laser cladding, a maximum hardness of 1100 HV is achieved in the laser cladding surface layer, which is more three times higher than that of the TC2 substrate (∼300 HV). Due to the formation of TiC and TiB2 intermetallic compounds in the alloyed region and grain refinement, the microhardness of coating is higher than TC2 Ti alloy. In this paper, the corrosion property of matrix material and treated samples were both measured in NaCl (3.5 wt%) aqueous solution. From the result we can see that the laser cladding specimens' corrosion property is clearly becoming better than that of the substrate.

  7. Analysis of the Coupling Effects of TiB Whiskers and TiC Particles on the Fracture Toughness of (TiB + TiC)/TC4 Composites: Experiment and Modeling

    NASA Astrophysics Data System (ADS)

    Lu, Weijie; Guo, Xianglong; Meng, Jialin; Wang, Fangqiu; Wang, Liqiang; Zhang, Di

    2015-08-01

    (TiB + TiC)/TC4 composites reinforced with different amounts of TiB whiskers and TiC particles are produced by common casting and hot forging technology. Then the fracture toughness of (TiB + TiC)/TC4 composites is analyzed by experiment and modeling. The experimental results indicate that not only reinforcement volume fraction but also the mole ratio between TiB whiskers and TiC particles can influence the fracture toughness of (TiB + TiC)/TC4 composites. Microstructure observations are carried out to examine the behavior of TiB whiskers and TiC particles in the fracture process. An analytical expression for predicting the fracture toughness of (TiB + TiC)/TC4 composites is built up. In particular, the coupling influences of TiB whiskers and TiC particles on the elastic modulus, yield strength, and fracture strain of TMCs are revealed in the modeling process. The results indicate that when TiB and TiC particles are coexisting in the TMCs, the fracture toughness of (TiB + TiC)/TC4 composites increases with the increase of the TiB whiskers aspect ratio, TiC particles volume fraction and size; however, with the increase of TiB whiskers volume fraction, the fracture toughness decreases. The breakage of TiB whiskers is the main reason for the fracture of TMCs. The acting mechanism of TiC particles on the fracture of TMCs transfers from blocking crack propagation and interfacial debonding to breakage with the increase of size, which can decrease the fracture toughness of (TiB + TiC)/TC4 composites. Considering the broken fraction of TiB whiskers, the fracture toughness of (TiB + TiC)/TC4 composites can be reasonably predicted.

  8. Titanium alloy corrosion in nuclear waste environments. [Ti-50A; TiCode 12; Ti-Pd

    SciTech Connect

    Braithwaite, J.W.; Magnani, N.J.; Munford, J.W.

    1980-01-01

    A corrosion study has been conducted on the titanium alloys Ti-50A, TiCode 12, and Ti-Pd to evaluate their suitability as a long lifetime (300 to 600 year) canister material for the isolation of nuclear wastes. TiCode 12, selected as the primary candidate material, is shown to be very resistant to environmental attack. Results of electrochemical, general corrosion, and stress corrosion cracking experiments are presented. These data, including those from severe overtests, have shown that TiCode 12 is a viable candidate material for long-term waste isolation. 17 figures.

  9. Electrical conduction of Ti/TiOx/Ti structures at low temperatures and high magnetic fields

    NASA Astrophysics Data System (ADS)

    Batkova, Marianna; Batko, Ivan

    2016-03-01

    We present results of electrical conduction studies of Ti/TiOx/Ti planar structures prepared by tip-induced local anodic oxidation (LAO) of titanium thin films. The prepared structures have shown almost linear I-V curves at temperatures between 300 K and 30 K, and only slight deviation from linear behaviour at lower temperatures. Electrical conductance of the structures can be adequately explained by a two-channel model where variable range hopping channels and metallic ones coexist in parallel, while a crossover from Mott to Efros-Shklovskii variable-range-hopping conductivity has been observed at decreasing temperature. The magnetoresistance of the studied structures is very small even in magnetic fields up to 9 T. The reported electrical properties of the structures indicate their promising applications as very low heat capacity temperature sensors for cryogenic region and high magnetic fields.

  10. Study of preparation of TiB{sub 2} by TiC in Al melts

    SciTech Connect

    Ding Haimin; Liu Xiangfa; Nie Jinfeng

    2012-01-15

    TiB{sub 2} particles are prepared by TiC in Al melts and the characteristics of them are studied. It is found that TiC particles are unstable when boron exists in Al melts with high temperature and will transform to TiB{sub 2} and Al{sub 4}C{sub 3}. Most of the synthesized TiB{sub 2} particles are regular hexagonal prisms with submicron size. The diameter of the undersurfaces of these prisms is ranging from 200 nm to 1 {mu}m and the height is ranging from 100 nm to 300 nm. It is considered that controlling the transformation from TiC to TiB{sub 2} is an effective method to prepare small and uniform TiB{sub 2} particles. - Highlights: Black-Right-Pointing-Pointer TiC can easily transform into TiB{sub 2} in Al melts. Black-Right-Pointing-Pointer TiB{sub 2} formed by TiC will grow into regular hexagonal prisms with submicron size. Black-Right-Pointing-Pointer Controlling the transformation from TiC to TiB{sub 2} is an effective method to prepare small and uniform TiB{sub 2} particles.

  11. Properties of TiAlN coating deposited by MPIIID on TiN substrates

    NASA Astrophysics Data System (ADS)

    El-Hossary, F. M.; Abd El-Rahman, A. M.; Raaif, M.; Ghareeb, D. A.

    2016-03-01

    Metal plasma immersion ion implantation and deposition (MPIIID) is employed to produce TiAlN hard coatings on Ti substrate. To improve the load-bearing capacity of Ti substrate, nitrogen PIII is used to prepare a bearing TiN layer on Ti-base substrate. The MPIIID process is performed using Ti50:Al50 target for different nitrogen/argon gas fractions. The effect of N2/Ar gas ratio on the microstructure, mechanical and tribological properties of TiAlN coatings has been studied. The plastic microhardness of TiAlN increases with increasing the nitrogen gas fraction to reach a maximum value of 30 GPa at 100 % N2. The plasticity index and the resistance to plastic deformation increase with increasing the nitrogen gas fraction. The wear volume loss of TiAlN coating deposited on TiN substrate decreases by a factor of 103 in comparison with pure Ti. Moreover, the friction coefficient decreases from nearly 0.8 for Ti to 0.25 for TiAlN coatings. The enhanced mechanical and tribological properties of the coating are correlated with the formation of TiAlN hard phase. This phase has random-oriented microstructure, finer grain size, high oxidation resistance and residual internal stress. Moreover, the TiN interface acts as a barrier for the motion of dislocations.

  12. Tribological properties of biocompatible Ti-10W and Ti-7.5TiC-7.5W.

    PubMed

    Choi, Myounggeun; Hong, Eunji; So, Jungwon; Song, Seokbeom; Kim, Byoung-Suck; Yamamoto, Akiko; Kim, Yong-Suk; Cho, Jinhan; Choe, Heeman

    2014-02-01

    This study investigates and compares the microstructure, biocompatibility, and tribological properties of two different Ti-based composites, Ti-10W and Ti-7.5TiC-7.5W, with those of pure Ti for their potential use in biomedical applications. In particular, cold and hot isostatic-pressing and arc-melting methods were utilized and compared for the microstructure of the composites. Nano-scratch measurements and pin-on-disk wear tests were employed to understand their tribological behavior. As compared to pure Ti, Ti-10W and Ti-7.5TiC-7.5W showed significantly improved nano-scratch resistance (by 85 and 77%, respectively) and wear resistance (by 64 and 66%, respectively), in good agreement with hardness measurements. For biocompatibility examination, both microculture tetrazolium test (MTT) and water soluble tetrazolium (WST-1) test were used to quantify the cell viability of human osteoblasts and mouse fibroblasts on the materials. Both of the Ti-based composites showed acceptable biocompatibility in comparison with the pure Ti control. PMID:24333672

  13. Low-cost bidirectional selector based on Ti/TiO2/HfO2/TiO2/Ti stack for bipolar RRAM arrays

    NASA Astrophysics Data System (ADS)

    Li, Yingtao; Li, Rongrong; Yuan, Peng; Gao, Xiaoping; Chen, Enzi

    2015-12-01

    In this paper, a low-cost Ti/TiO2/HfO2/TiO2/Ti stack structure is proposed as a selector for bipolar resistive random access memory (RRAM) cross-bar array applications. We demonstrate reproducible resistive switching characteristics with significant nonlinearity and good uniformity in the one selector and one resistor (1S1R) structure device that integrate the bidirectional selector with a bipolar Pt/Ti/HfO2/Pt RRAM device. These results provide a good point of reference for evaluating the potential low-cost applications in bipolar RRAM cross-bar array.

  14. Mapping Stars with TI-83.

    ERIC Educational Resources Information Center

    Felsager, Bjorn

    2001-01-01

    Describes a mathematics and science project designed to help students gain some familiarity with constellations and trigonometry by using the TI-83 calculator as a tool. Specific constellations such as the Big Dipper (Plough) and other sets of stars are located using stereographic projection and graphed using scatterplots. (MM)

  15. Ti-based glassy alloys in Ti-Cu-Zr-Sn system

    NASA Astrophysics Data System (ADS)

    Wang, ZengRui; Dong, DanDan; Qiang, JianBing; Wang, Qing; Wang, YingMin; Dong, Chuang

    2013-07-01

    Bulk amorphous formation in Ti-Cu-based multicomponent alloys, free of Ni, Pd and Be elements, were studied using the cluster-plus-glue-atom model. The basic cluster formula was revealed as [Ti9Cu6]Cu3 to explain the best binary glass forming composition Ti50Cu50=Ti9Cu9, where the CN14 rhombi-dodecahedron Ti9Cu6 was the principal cluster in the devitrification phase CuTi. This basic cluster formula was further alloyed with Zr and Sn and a critical glass forming ability was reached at (Ti7.2Zr1.8)(Cu8.72Sn0.28) and (Ti7.2Zr1.8)(Cu8.45Sn0.55) up to 5 mm in diameter by suction casting, which was the largest in Ti-Cu-based and Ni-, Pd- and Be-free alloys.

  16. Synthesis and characterization of TiO2 and Ag/TiO2 nanostructure

    NASA Astrophysics Data System (ADS)

    Gahlot, Swati; Thakur, Amit Kumar; Kulshrestha, Vaibhav; Shahi, V. K.

    2013-02-01

    Single phase anatase TiO2 nanoparticles were prepared using Titanium tertachloride (TiCl4) as precursor through an inexpensive method. Well dispersed nanocomposites of silver at TiO2 were synthesized successfully by photochemical route. Both TiO2 and Ag/TiO2 were characterized using X-Ray Diffraction (XRD) and transmission electron microscopy (TEM). The particle size of TiO2 is found to be ˜ 11 nm and ˜ 22 nm for Ag/TiO2, by XRD and confirmed by TEM. TEM micrographs also show the single phase crystal of TiO2 and confirm the deposition of silver among TiO2.

  17. Investigation on W/Fe diffusion bonding using Ti foil and Ti powder interlayer by SPS

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Yu; Luo, Lai-Ma; Zhang, Jun; Zan, Xiang; Zhu, Xiao-Yong; Luo, Guang-Nan; Wu, Yu-Cheng

    2015-12-01

    W/steel composites are being developed for potential application in He gas-cooled divertors and plasma-facing components in fusion reactors. In this study, the dissimilar metal joints between W and Fe were fabricated at 950 °C via spark plasma sintering method with Ti foil (Ti-F) and Ti powder (Ti-P) as the interlayer under Ar atmosphere for 5 min at 57 MPa. Microscopic structures of the W/Fe diffusion joints with Ti-F and Ti-P were investigated and compared via field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermal cycling tests were employed to measure the thermal stability of different types of W/Ti/Fe samples. The hardness distribution across joining interfaces was also determined. After thermal cycling tests, a crack occurred along the W/Ti-P interface in the W/Ti-P/Fe samples, whereas the W/Ti-F/Fe samples were intact at the interfaces. Results revealed that Ti-F is more suitable as an interlayer than Ti-P, and the interfaces of the W/Ti-F/Fe samples have better thermal stability than those of the W/Ti-P/Fe ones.

  18. Reactive sintering of TiAl–Ti5Si3 in situ composites

    SciTech Connect

    Alman, David E.

    2005-06-01

    TiAl with between 0 and 20 vol%Ti5Si3 was produced by reactive sintering (700 °C for 15 min in vacuum) of cold pressed compacts of elemental Ti, Al and Si powder. The results show that adding Si to Ti and Al reduces the swelling associated with reactive sintering of TiAl, as composites containing more than 5 vol%Ti5Si3 densified during reactive sintering. However, composites containing more than 10 vol%Ti5Si3 did not retain their shape and the TiAl+20 vol%Ti5Si3 composite completely melted during the sintering process. A thermodynamic analysis indicated that the simultaneous formation of TiAl and Ti5Si3 increases the adiabatic flame temperature during the reaction between the powders. In fact, the analysis predicted that the maximum temperature of the reaction associated with the formation TiAl+20 vol%Ti5Si3 should exceed the melting point of TiAl, and this was observed experimentally. Differential thermal analysis (DTA) revealed that an Al–Si eutectic reaction occurred in mixtures of Ti, Al and Si powders prior to the formation of the TiAl and Ti5Si3 phases. There was no such pre-reaction formation of a eutectic liquid in Ti and Al powder mixtures. The formation of the pre-reaction liquid and the increase in adiabatic flame temperature resulted in the melting that occurred and the enhanced densification (minimization of swelling) during reactive sintering of the in situ composites.

  19. Experimental study on the osseointegration of foam TiC/Ti composites.

    PubMed

    Jingyu, Wang; Lin, Wu; Yong, Gao; Jinsong, Zhang; Cuicui, Zhang

    2013-08-01

    Macroporous ceramics have demonstrated osteoconductive properties because of their biocompatibility and 3D macroporous structure, and these materials have recently been widely studied as bone replacement materials. The foam TiC/Ti composites discussed in this study have good mechanical properties, balancing out metallic toughness and ceramic strength. Furthermore, because of the high porosity and pore connectivity of these TiC/Ti composites, they have the potential to be a new bone replacement material. The purpose of this study was to evaluate the osseointegration of foam TiC/Ti composites, preliminarily discuss the TiC/Ti ossification mechanism, and to obtain reliable data on the use of foam TiC/Ti composites as bone replacement materials. The foam TiC/Ti composites were sited in 40 Japanese white rabbits for 4, 8, 12 and 24 weeks. The foam TiC/Ti composites were compared to foam SiC. M-CT (micro-computed tomography) analysis, histological analysis, SEM (scanning electron microscopy) observation and EDS (energy-dispersive x-ray spectrometer) analysis were conducted to estimate the osseointegration of the materials. The histological observations and quantitative analysis exhibited significantly more ossification area (volume), trabeculae maturity, and calcium and phosphorus content in the foam TiC/Ti composites compared to the foam SiC (p < 0.05). The results from this study suggest that the foam TiC/Ti composites possess good osseointegration capacity and have the potential to be a new bone replacement material. PMID:23715099

  20. Mono- and multiple TiN(/Ti) coating adhesion mechanism on a Ti-13Nb-13Zr alloy

    NASA Astrophysics Data System (ADS)

    Li, Jianzhong; Zheng, Hua; Sinkovits, Theo; Hee, Ay Ching; Zhao, Yue

    2015-11-01

    Mono- and multiple TiN(/Ti) coatings deposited on Ti-13Nb-13Zr alloy substrates by the filtered arc deposition system were examined using scratch testing and depth-sensing indentation in terms of the relationship between the coating adhesion, deformation mechanism, and microstructure, and mechanical properties at the film/substrate interface. The results show that multilayer TiN/Ti coatings offer a greater resistance to cracking and delamination than monolithic TiN coatings under the same conditions on the Ti-13Nb-13Zr alloys substrates. And increasing the number of layers for TiN multilayer coating improves the coatings adhesion. In contrast, for the coatings on the Ti-13Nb-13Zr alloys substrates that were heat-treated to a higher hardness, the limited deformation in the substrates improved remarkably the coating adhesion indiscriminately. The substrate mechanical properties play the major roles in controlling the coating adhesion, and increasing thickness and layers of the TiN multilayer have a limited improvement to the adhesion of coating.

  1. Electromigration performance improvement of Al-Si-Cu/TiN/Ti/n+Si contact

    NASA Astrophysics Data System (ADS)

    Shi, Gang; Sun, Zhen; Xu, Geng-Fu; Min, Yun-Hao; Luo, Jun-Yi; Lu, Yong; Li, Bing-Zong; Qu, Xin-Ping; Qian, Gang; Doan, My T.; Lee, Edmund

    1998-02-01

    In this study, two different processes, with and without rapid thermal annealing (RTA), have been compared for the Al-Si- Cu/TiN/Ti multilayer contact on n+ diffusions. A series of wafer level reliability (WLR) measurement performed on a test structure with two 1.08 X 1.08 micrometer2 contacts on n+ diffusion. The results show that RTA can increase contact electromigration (EM) lifetime dramatically. The XRD, AES and TEM analysis indicate that this improvement is attributed to oxygen stuffing in TiN, phase change of TiN and TiSi2 formation at the interface of Ti and Si.

  2. Study and characterization of the irreversible transformation of electrically stressed planar Ti/TiO{sub x}/Ti junctions

    SciTech Connect

    Guillaume, N.; Puyoo, E. Le Berre, M.; Albertini, D.; Baboux, N.; Chevalier, C.; Ayadi, K.; Grégoire, J.; Gautier, B.; Calmon, F.

    2015-10-14

    We investigate the properties and characteristics of planar Ti/TiO{sub x}/Ti junctions, which consist of transverse TiO{sub x} lines drawn on Ti test patterns. Junctions are elaborated by means of local anodic oxidation using atomic force microscopy. An irreversible morphological transformation occurring in a reproducible manner is observed when these planar junctions are electrically stressed under ambient atmosphere. Structural and chemical analyses based on transmission electron microscopy techniques reveal the extension of the initial amorphous TiO{sub x} into a crystalline rutile phase. This irreversible transformation is proven to vanish completely if the electrical stress occurs under vacuum atmosphere. Finally, we carry out temperature dependent electrical measurements in order to elucidate their conduction mechanism: Schottky emission above an ultra-low potential barrier is assumed to dominate under vacuum atmosphere whereas ionic conduction seems to prevail in air.

  3. The Interface of TiB2 and Al3Ti in Molten Aluminum

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; Song, Jie; Vian, Wei; Ma, Haibin; Han, Qingyou

    2015-12-01

    In the grain refinement of aluminum, Al3Ti and TiB2 particles are introduced to reduce the casting grain size down to 200 micrometer level, which makes cold working possible. The particles are brought in by the addition of Al-Ti-B-type master alloys. It is generally believed that TiB2 particles are stable and nucleate α-Al grains in solidification in the presence of titanium in solution from the dissolution of Al3Ti particles in the master alloys. The titanium in solution either forms Al3Ti layers on the surface of TiB2 particles to promote the nucleation of α-Al grains or remains as solute to restrict the growth of α-Al grains in solidification. However, a consensus on a grain refinement mechanism is still to be reached due to the lack of direct observation of the three phases in castings. This paper presents finding of the TiB2/Al3Ti interfaces in an Al-Ti-B master alloy. It demonstrates a strong epitaxial growth of Al3Ti on the surface of TiB2 particles, a sign of the formation of an Al3Ti layer on the surface of TiB2 particles in grain refinement practice. The Al3Ti layer has a crystal coherency with α-Al and hence offers a substrate for heterogeneous nucleation of α-Al grains. However, the layer must be dynamic to avoid the formation of compounded Al3Ti and TiB2 particles leading to the loss of efficiency in grain refinement.

  4. Multilayer nano Ti/TiO{sub 2}-Pt electrode for coal-hydrogen production

    SciTech Connect

    Yin, R.H.; Ji, X.B.; Zhang, L.; Lu, S.Y.; Cao, W.G.; Fan, Q.B.

    2007-07-01

    Multilayer nanoporous Ti/TiO{sub 2} films were obtained by controlling electro-oxidation potentials in a sulfuric acid solution. After etching in a dilute hydrogen fluoride solution, the porous layers were deposited and intercalated with Pt and Pt-Ru to form Ti/TiO{sub 2}-Pt and Ti/TiO{sub 2}-PtRu electrodes by using the cyclic voltammetric method. An electron diffraction spectroscopy was used to examine the electrode surface structure. The catalytic activity of the electrodes for electro-oxidation of coal shows that the multilayer nanoporous Ti/TiO{sub 2}-Pt structure improves the electrode performance in comparison to a pure Pt electrode and a Pt coated Ti electrode. The Ti/TiO{sub 2}-Pt-Ru (1: 2) electrode shows even better catalytic activity than the Ti/TiO{sub 2}-Pt. Anode gas analysis shows that the coal electro-oxidation produces mainly CO{sub 2} with trace amount of CO and the cathode gas is pure hydrogen. We also observed some lower hydrocarbon by-products, such as methane. The amount of CO{sub 2} is only about 10% of the amount of H{sub 2} produced.

  5. B-Ni-Ti (164)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'B-Ni-Ti (164)' with the content:

  6. Investigation of TiC/Si{sub 3}N{sub 4} and TiN-coated TiC/Si{sub 3}N{sub 4} composites

    SciTech Connect

    Jow-Lay Huang; Boy-Yuan Shew; Ding-Fwu Lii

    1996-12-31

    Silicon nitride containing various compositions of as received TiC and TiN-coated TiC were hot pressed at 1800{degrees}C for 1 h in a nitrogen atmosphere. In TiN-coated TiC/Si{sub 3}N{sub 4} composites, TiC reacted firstly with the TiN coating to form a titanium carbonitride interlayer at 1450{degrees}C, which essentially reduced further reactions between TiC and Si{sub 3}N{sub 4} and enhanced densification. TiN-coated TiC/Si{sub 3}N{sub 4} composites exhibited better densification, flexural strength and fracture toughness than those of as received TiC/Si{sub 3}N{sub 4}.

  7. Oxide Scales Formed on NiTi and NiPtTi Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Garg, Anita; Rogers, Richard B.; Noebe, Ronald D.

    2011-01-01

    Ni-49Ti and Ni-30Pt-50Ti (at.%) shape memory alloys were oxidized isothermally in air over the temperature range of 500 to 900 C. The microstructure, composition, and phase content of the scales were studied by SEM, EDS, XRD, and metallography. Extensive plan view SEM/EDS identified various features of intact or spalled scale surfaces. The outer surface of the scale was a relatively pure TiO2 rutile structure, typified by a distinct highly striated and faceted crystal morphology. Crystal size increased significantly with temperature. Spalled regions exhibited some porosity and less distinct features. More detailed information was obtained by correlation of SEM/EDS studies of 700 C/100 hr cross-sections with XRD analyses of serial or taper-polishing of plan surfaces. Overall, multiple layers exhibited graded mixtures of NiO, TiO2, NiTiO3, Ni(Ti) or Pt(Ni,Ti) metal dispersoids, Ni3Ti or Pt3Ti depletion zones, and substrate, in that order. The NiTi alloy contained a 3 at.% Fe impurity that appeared in embedded localized Fe-Ti-rich oxides, while the NiPtTi alloy contained a 2 v/o dispersion of TiC that appeared in lower layers. The oxidation kinetics of both alloys (in a previous report) indicated parabolic growth and an activation energy (250 kJ/mole) near those reported in other Ti and NiTi studies. This is generally consistent with TiO2 existing as the primary scale constituent, as described here.

  8. Characteristics of heat resistant alloys Ti10Nb45Al and Ti18Nb48Al

    SciTech Connect

    Weijun Zhang; Guoliang Chen; Yandong Wang; Zuqing Sun )

    1993-05-01

    Based on a systematic study of the ternary Ti-Nb-Al system, two attractive heat resistant alloys, Ti10Nb45Al and Ti18Nb48Al, were developed, and the characteristics of these alloys were discussed: (1) After annealing at 1,200 C for 240 h and furnace cooling to room temperature, the Ti10Nb45Al alloy exhibits an [alpha][sub 2] + [gamma] lamellar microstructure, and the Ti18Nb48Al alloy shows a plate-like structure consisting of [alpha][sub 2], [gamma] and [gamma][sub 1] phases. (2) The specific strengths of Ti10Nb45Al and Ti18Nb48Al are much higher than TiAl and superalloys in the temperature range of 800 [approximately] 1,100 C. The compressive yield strengths of these alloys are on the order of 700 MPa at 800 C and 350 MPa at 1,100 C. The density of these alloys is about 4.3 g/cm[sup 3]. (3) The annealed Ti10Nb45Al and Ti18Nb48Al exhibit some ductility at room temperature, with the compressive elongation on the order of 12% and the fracture toughness as high as 16 MPa[radical]m. The ductile-brittle transformation temperatures for Ti10Nb45Al and Ti18Nb48Al are 650 C and 750 C, respectively. (4) The parabolic constant K[sub p] for oxidation of Ti10Nb45Al and Ti18Nb48Al are 0.88 and 0.29 mg[sup 2]cm[sup [minus]4]h[sup [minus]1] respectively, which are two orders of magnitude lower than that of TiAl and Ti[sub 3]Al alloys.

  9. On the peritectoid Ti{sub 3}Si formation in Ti-Si alloys

    SciTech Connect

    Ramos, Alfeu Saraiva . E-mail: alfeu@univap.br; Nunes, Carlos Angelo; Coelho, Gilberto Carvalho

    2006-03-15

    Ti-13.5Si and Ti-25Si (at.%) alloys have been arc-melted from high-purity raw materials, using a water-cooled copper hearth, a non-consumable tungsten electrode, and under an Ar atmosphere gettered by titanium. The cast ingots were then heat-treated for 90 h at 1000 and 1100 deg. C in an inert atmosphere, and both the as-cast and the heat-treated alloys were characterized using scanning electron microscopy and an energy dispersive microanalysis system. The as-cast Ti-13.5Si alloy presented a eutectic microstructure composed of the Ti{sub SS} and Ti{sub 5}Si{sub 3} phases, while the microstructure of the as-cast Ti-25Si alloy showed the presence of large primary precipitates of Ti{sub 5}Si{sub 3} in a eutectic matrix of Ti{sub SS} and Ti{sub 5}Si{sub 3}. Subsequent heat treatment at 1100 deg. C produced no significant microstructural modifications in the Ti-25Si alloy, and it is suggested that the presence of the large primary precipitates of Ti{sub 5}Si{sub 3} contributed to a reduction in the kinetics of Ti{sub 3}Si formation. In the Ti-13.5Si alloys, the formation of Ti{sub 3}Si was not observed after heat treatment at 1000 deg. C, but a large amount of Ti{sub 3}Si was found after heat treatment at 1100 deg. C, confirming its existence in Ti-Si alloys containing low interstitial contents.

  10. Point defect study of CuTi and CuTi sub 2

    SciTech Connect

    Shoemaker, J.R.; Lutton, R.T.; Wesley, D.; Wharton, W.R.; Oehrli, M.L.; Herte, M.S.; Sabochick, M.J. ); Lam, N.Q. )

    1991-03-01

    The energies and configurations of interstitials and vacancies in the ordered compounds CuTi and CuTi{sub 2} were determined using atomistic simulation with realistic embedded-atom potentials. The formation energy of an antisite pair was found to be 0.385 and 0.460 eV in CuTi and CuTi{sub 2}, respectively. In both compounds, the creation of a vacancy by the removal of either a Cu or Ti atom resulted in a vacant Cu site, with an adjacent antisite defect in the case of the Ti vacancy. The vacant Cu site in CuTi was found to be very mobile within two adjacent (001) Cu planes, with a migration energy of 0.19 eV, giving rise to two-dimensional migration. The vacancy migration energy across (001) Ti planes, however, was 1.32 eV, which could be lowered to 0.75 or 0.60 eV if one or two Cu antisite defects were initially present in these planes. In CuTi{sub 2}, the vacancy migration energy of 0.92 eV along the (001) Cu plane was significantly higher than in CuTi. The effective vacancy formation energies were calculated to be 1.09 eV and 0.90 eV in CuTi and CuTi{sub 2}, respectively. Interstitials created by inserting either a Cu or Ti atom had complicated configurations in which a Cu {l angle}111{r angle} split interstitial was surrounded by two or three Ti antisite defects. The interstitial formation energy was estimated to be 1.7 eV in CuTi and 1.9 eV in CuTi{sub 2}.

  11. 45Ti extraction using hydroxamate resin

    NASA Astrophysics Data System (ADS)

    Gagnon, K.; Severin, G. W.; Barnhart, T. E.; Engle, J. W.; Valdovinos, H. F.; Nickles, R. J.

    2012-12-01

    As an attractive radionuclide for positron emission tomography, this study explores the extraction and reactivity of 45Ti produced via the 45Sc(p,n)45Ti reaction on a GE PETtrace. Using a small hydroxamate column, we have demonstrated an overall recovery of >50% of 45Ti in ˜1 mL of 1M oxalic acid. Conditions for reacting with desferal were also explored, with effective specific activities up to 38 GBq/μmol obtained.

  12. Controllable Synthesis and Tunable Photocatalytic Properties of Ti(3+)-doped TiO2.

    PubMed

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti(3+)-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti(4+) on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti(3+)-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  13. Controllable Synthesis and Tunable Photocatalytic Properties of Ti3+-doped TiO2

    PubMed Central

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  14. Ti(3+) in meteoritic and synthetic hibonite

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  15. TiCl, TiH and TiH+ Bond Energies, a Test of a Correlation Consistent Ti Basis Set

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1999-01-01

    Correlation consistent basis sets are developed for Ti atom. The polarization functions are optimized for the average of the 3F and 5F states. One series of correlation consistent basis sets is for 3d and 4s correlation, while the second series includes 3s and 3p correlation as well as 3d and 4s correlation. These basis sets are tested using the Ti 3F-5F separation and the dissociation energies of TiCl X4Phi, TiH X4Phi, and TiH(+) X3Phi. The CCSD(T) complete basis set limit values are determined by extrapolation. The Douglas Kroll approach is used to compute the scalar relativistic effect. Spin-orbit effects are taken from experiment and/or computed at the CASSCF level. The Ti 3F-5F separation is in excellent agreement with experiment, while the TiCl, TiH, and TiH(+) bond energies are in good agreement with experiment. Extrapolation with the valence basis set is consistent with other atoms, while including 3s and 3p correlation appears to make extrapolation.

  16. Synthesis of Ti/TiN/TiCN coatings grown in graded form by sputtering dc

    NASA Astrophysics Data System (ADS)

    Agudelo, L. C.; Ospina, R.; Castillo, H. A.; Devia, A.

    2008-10-01

    Graded coatings have the advantage of having gradual properties such as thermal expansion coefficient and lattice parameter, avoiding adherence problems due to good match between their component materials. In this work, some properties of coatings grown in graded form are presented. The materials were produced using the sputtering dc technique because of its facility to control the deposition parameters and generate homogeneous growth. The target is a disc of titanium and the samples are made of stainless steel 304. The working gases are argon, nitrogen and methane, which are mixed according to the material to be produced. Titatnium (Ti) layer is grown with argon, the titanium nitride (TiN) film is produced with a mixture of argon and nitrogen, and the titanium nitride carbon (TiCN) material is obtained mixing argon (Ar), nitrogen (N2) and methane (CH4). These materials are characterized with scanning probe microscopy (SPM) in atomic force microscopy (AFM) mode in order to determine grain size and with x-ray photoelectron spectroscopy (XPS) studying the chemical composition and performing depth profiles.

  17. Porous NiTi shape memory alloys produced by SHS: microstructure and biocompatibility in comparison with Ti2Ni and TiNi3.

    PubMed

    Bassani, Paola; Panseri, Silvia; Ruffini, Andrea; Montesi, Monica; Ghetti, Martina; Zanotti, Claudio; Tampieri, Anna; Tuissi, Ausonio

    2014-10-01

    Shape memory alloys based on NiTi have found their main applications in manufacturing of new biomedical devices mainly in surgery tools, stents and orthopedics. Porous NiTi can exhibit an engineering elastic modulus comparable to that of cortical bone (12-17 GPa). This condition, combined with proper pore size, allows good osteointegration. Open cells porous NiTi was produced by self propagating high temperature synthesis (SHS), starting from Ni and Ti mixed powders. The main NiTi phase is formed during SHS together with other Ni-Ti compounds. The biocompatibility of such material was investigated by single culture experiment and ionic release on small specimen. In particular, NiTi and porous NiTi were evaluated together with elemental Ti and Ni reference metals and the two intermetallic TiNi3, Ti2Ni phases. This approach permitted to clearly identify the influence of secondary phases in porous NiTi materials and relation with Ni-ion release. The results indicated, apart the well-known high toxicity of Ni, also toxicity of TiNi3, whilst phases with higher Ti content showed high biocompatibility. A slightly reduced biocompatibility of porous NiTi was ascribed to combined effect of TiNi3 presence and topography that requires higher effort for the cells to adapt to the surface. PMID:24928669

  18. Highly uniform bipolar resistive switching characteristics in TiO{sub 2}/BaTiO{sub 3}/TiO{sub 2} multilayer

    SciTech Connect

    Ma, W. J.; Zhang, X. Y.; Wang, Ying; Zheng, Yue E-mail: wangbiao@mail.sysu.edu.cn; Lin, S. P.; Luo, J. M.; Wang, B. E-mail: wangbiao@mail.sysu.edu.cn; Li, Z. X.

    2013-12-23

    Nanoscale multilayer structure TiO{sub 2}/BaTiO{sub 3}/TiO{sub 2} has been fabricated on Pt/Ti/SiO{sub 2}/Si substrate by chemical solution deposition method. Highly uniform bipolar resistive switching (BRS) characteristics have been observed in Pt/TiO{sub 2}/BaTiO{sub 3}/TiO{sub 2}/Pt cells. Analysis of the current-voltage relationship demonstrates that the space-charge-limited current conduction controlled by the localized oxygen vacancies should be important to the resistive switching behavior. X-ray photoelectron spectroscopy results indicated that oxygen vacancies in TiO{sub 2} play a crucial role in the resistive switching phenomenon and the introduced TiO{sub 2}/BaTiO{sub 3} interfaces result in the high uniformity of bipolar resistive switching characteristics.

  19. Laser processing of in situ TiN/Ti composite coating on titanium.

    PubMed

    Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

    2016-01-01

    Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding. PMID:26344856

  20. Influence of TiN coating on the biocompatibility of medical NiTi alloy.

    PubMed

    Jin, Shi; Zhang, Yang; Wang, Qiang; Zhang, Dan; Zhang, Song

    2013-01-01

    The biocompatibility of TiN coated nickel-titanium shape memory alloy (NiTi-SMA) was evaluated to compare with that of the uncoated NiTi-SMA. Based on the orthodontic clinical application, the surface properties and biocompatibility were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), wettability test, mechanical test and in vitro tests including MTT, cell apoptosis and cell adhesion tests. It was observed that the bonding between the substrate and TiN coating is excellent. The roughness and wettability increased as for the TiN coating compared with the uncoated NiTi-SMA. MTT test showed no significant difference between the coated and uncoated NiTi-SMA, however the percentage of early cell apoptosis was significantly higher as for the uncoated NiTi alloy. SEM results showed that TiN coating could enhance the cell attachment, spreading and proliferation on NiTi-SMA. The results indicated that TiN coating bonded with the substrate well and could lead to a better biocompatibility. PMID:23010039

  1. Controllable hydrothermal synthesis of rutile TiO{sub 2} hollow nanorod arrays on TiCl{sub 4} pretreated Ti foil for DSSC application

    SciTech Connect

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-11-15

    Rutile TiO{sub 2} nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl{sub 4} pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO{sub 2} nanorod arrays (H-TNRs). The TiCl{sub 4} pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl{sub 4} concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ∼1.5 μm and diameter of ∼200 nm, obtained on 0.15 M TiCl{sub 4} pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl{sub 4}-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode. - Graphical abstract: Rutile hollow TiO{sub 2} nanorod array photoanode obtained from original TiO{sub 2} nanorod array photoanode by hydrothermal etching demonstrates enhanced photoelectric efficiency of DSSC. - Highlights: • TiO{sub 2} nanorods are prepared via hydrothermal process on TiCl{sub 4}-pretreated Ti foil. • Hollow TiO{sub 2} nanorods are obtained by hydrothermal etching of TiO{sub 2} nanorods. • TiCl{sub 4} pretreatment plays a key role in protecting Ti foil from chemical corrosion. • Hollow TiO{sub 2} nanorods photoanode shows enhanced photoelectric efficiency for DSSC.

  2. Durability Assessment of TiAl Alloys

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Lerch, Bradley A.

    2008-01-01

    The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

  3. XPS investigations of tribolayers formed on TiN and (Ti,Re)N coatings

    NASA Astrophysics Data System (ADS)

    Oktay, Serkan; Kahraman, Zafer; Urgen, Mustafa; Kazmanli, Kursat

    2015-02-01

    TiN and (Ti,Re)N coatings were deposited on high-speed-steel substrates by a hybrid coating system composed of cathodic arc PVD and magnetron sputtering techniques. In order to keep rhenium content low (8 ± 1.9 at.%) in the coating, magnetron sputtering technique was utilized to evaporate rhenium. The (Ti,Re)N coating consisted of TiN and ReNx (x > 1.33) phases. The hardness of TiN and (Ti,Re)N were 31 GPa and 29 GPa (± 2 GPa), respectively. Tribological behaviors of the samples were tested against Al2O3 balls at 21 °C (RT) and 150 °C (HT) by reciprocating wear technique. The tribolayers were analyzed by XPS technique. Friction coefficients of TiN were 0.56, 0.35 for 21 °C and 150 °C tests, respectively. Rhenium addition to TiN drastically dropped the friction coefficients to 0.22 and 0.17 for RT and HT samples. Rhenium addition also improved the wear resistance of the coating at both test temperatures. For TiN, main oxide component of the tribolayers was Ti2O3 for RT tests and TiO2 for HT tests. The oxide layer formed on (Ti,Re)N were the mixture of TiO2, Tisbnd Osbnd N, ReO2 and Re2O7 for both test temperatures. Re2O7 provided very low friction coefficient to (Ti,Re)N. The findings are consistent with the crystal chemistry approach.

  4. Fabrication of Powder Metallurgy Pure Ti Material by Using Thermal Decomposition of TiH2

    NASA Astrophysics Data System (ADS)

    Mimoto, Takanori; Nakanishi, Nozomi; Umeda, Junko; Kondoh, Katsuyoshi

    Titanium (Ti) and titanium alloys have been interested as an engineering material because they are widely used across various industrial applications, for example, motorcycle, automotive and aerospace industries, due to their light weight, high specific strength and superior corrosion resistance. Ti materials are particularly significant for the aircraft using carbon/carbon (C/C) composites, for example, carbon fiber reinforced plastics (CFRP), because Ti materials are free from the problem of contact corrosion between C/C composites. However, the applications of Ti materials are limited because of their high cost. From a viewpoint of cost reduction, cost effective process to fabricate Ti materials is strongly required. In the present study, the direct consolidation of titanium hydride (TiH2) raw powders in solid-state was employed to fabricate pure Ti bulk materials by using thermal decomposition of TiH2. In general, the production cost of Ti components is expensive due to using commercially pure (CP) Ti powders after dehydrogenation. On the other hand, the novel process using TiH2 powders as starting materials is a promising low cost approach for powder metallurgy (P/M) Ti products. Furthermore, this new process is also attractive from a viewpoint of energy saving because the dehydrogenation is integrated into the sintering process. In this study, TiH2 raw powders were directly consolidated by conventional press technique at 600 MPa to prepare TiH2 powder compacted billets. To thermally decompose TiH2 and obtain sintered pure Ti billets, the TiH2 powder billets were heated in the integrated sintering process including dehydrogenation. The hot-extruded pure Ti material, which was heat treated at 1273 K for 180 min in argon gas atmosphere, showed tensile strength of 701.8 MPa and elongation of 27.1%. These tensile properties satisfied the requirements for JIS Ti Grade 4. The relationship between microstructures, mechanical properties response and heat treatment

  5. Absolute isotopic abundances of TI in meteorites

    NASA Astrophysics Data System (ADS)

    Niederer, F. R.; Papanastassiou, D. A.; Wasserburg, G. J.

    1985-03-01

    The absolute isotope abundance of Ti has been determined in Ca-Al-rich inclusions from the Allende and Leoville meteorites and in samples of whole meteorites. The absolute Ti isotope abundances differ by a significant mass dependent isotope fractionation transformation from the previously reported abundances, which were normalized for fractionation using 46Ti/48Ti. Therefore, the absolute compositions define distinct nucleosynthetic components from those previously identified or reflect the existence of significant mass dependent isotope fractionation in nature. The authors provide a general formalism for determining the possible isotope compositions of the exotic Ti from the measured composition, for different values of isotope fractionation in nature and for different mixing ratios of the exotic and normal components.

  6. TiC reinforced cast Cr steels

    SciTech Connect

    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 steels were comparable to that of AISI 440C steel, but the impact resistance was much improved.

  7. Characteristics of Ti-Nb, Ti-Zr and Ti-Al containing hydrogenated carbon nitride films

    NASA Astrophysics Data System (ADS)

    Balaceanu, M.; Braic, V.; Braic, M.; Vladescu, A.; Zoita, C. N.; Grigorescu, C. E. A.; Grigore, E.; Ripeanu, R.

    2009-10-01

    Nanocomposite Me-C-N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ratios, were prepared by cathodic arc method using TiNb, TiZr and TiAl alloy cathodes in a CH 4 + N 2 atmosphere. For comparison purposes, a-C-N:H films were also produced through evaporating a graphite cathode in a similar atmosphere. The films were characterized in terms of elemental and phase compositions, chemical bonds, texture, hardness, adhesion and friction behavior by GDOES, XPS, Raman spectroscopy and XRD techniques, surface profilometry, hardness and scratch adhesion measurements, and tribological tests. The nanocomposite films consisted of a mixture of crystalline metal carbonitride and amorphous carbon nitride. The non-metal/metal ratio in the films composition was found to range between 1.8 and 1.9. For the metal containing nanocomposites, grain size in the range 7-23 nm, depending on the metal nature, were determined. As compared with the a-C-N:H, the Me-C-N:H films exhibited a much higher hardness (up to about 39 GPa for Ti-Zr-C-N:H) and a better adhesion strength, while the coefficients of friction were somewhat higher (0.2-0.3 for Me-C-N:H and 0.1 for a-C-N:H).

  8. Fabrication and nanoindentation properties of TiN/NiTi thin films and their applications in electrochemical sensing.

    PubMed

    Kumar, Ashvani; Singh, Devendra; Goyal, Rajendra N; Kaur, Davinder

    2009-05-15

    Nanocrystalline TiN/NiTi thin films have been grown on silicon substrate by dc magnetron sputtering to improve the corrosion and mechanical properties of NiTi based shape memory alloys without sacrificing the phase transformation effect. Interestingly, the preferential orientation of the TiN films was observed to change from (1 1 1) to (2 0 0) with change in nature of sputtering gas from 70% Ar+30% N(2) to 100% N(2). In present study the influence of crystallographic orientation of TiN on mechanical and corrosion properties of TiN/NiTi thin films was investigated. TiN (2 0 0)/NiTi films were found to exhibit high hardness, high elastic modulus, and thereby better wear resistance as compared to pure NiTi and TiN (1 1 1)/NiTi films. Electrochemical test revealed that TiN coated NiTi film exhibits better corrosion resistance in 1M NaCl solution as compared to uncoated NiTi film. The application of TiN/NiTi films in the electrochemical sensing of dopamine, which has a critical physiological importance in Parkinson's disease, has been demonstrated. A comparison of voltammetric response of dopamine at silicon based electrodes modified with different nanocrystalline coatings indicated that these films catalyze the oxidation of dopamine. PMID:19269458

  9. Ternary compounds and phase equilibria in Ti-Ge-C and Ti-Ge-B

    SciTech Connect

    Kephart, J.S.; Carim, A.H.

    1998-09-01

    Bulk samples of nearly single-phase Ti{sub 2}GeC and Ti{sub 3}GeC{sub 2} were fabricated using a synthesis process similar to one developed to produce bulk Ti{sub 3}SiC{sub 2}. Elemental powders were stored and mixed under argon and 2 g pellets were uniaxially pressed and encapsulated in quartz under vacuum for annealing. Additional samples were synthesized to establish the isothermal section of the ternary Ti-Ge-C phase diagram at 1200 C. The only ternary compounds present were Ti{sub 3}GeC{sub 2} and Ti{sub 2}GeC, and the equilibria between these and other phases in the system were established for the first time. Attempts at substituting boron for carbon in Ti{sub 3}GeC{sub 2} and Ti{sub 2}GeC by the same technique proved unsuccessful. The phase distributions in Ti-Ge-B samples at 1200 C were consistent with a previously established ternary diagram at 700 C which indicated that no ternary phases of this or any other type are present at equilibrium in the Ti-Ge-B system.

  10. Calculation of defect properties of NiTi and FeTi

    SciTech Connect

    Lutton, R.T.; Sabochick, M.J. . Dept. of Engineering Physics); Lam, N.Q. )

    1990-12-01

    The energies and configurations of interstitials and vacancies in the B2 ordered compounds NiTi and FeTi were calculated using atomistic simulation. The stable configuration of a vacancy after the removal of an Ni atom was a vacant Ni site; similarly, the removal of an Fe atom in FeTi resulted in a vacant Fe site. Removal of a Ti atom in both compounds, however, resulted in a vacant Ni or Fe site and an adjacent antisite defect. The effective vacancy formation energies in NiTi and FeTi were calculated to be 1.48 and 1.07 eV, respectively. Interstitials in NiTi formed split {l angle}111{r angle} configurations consisting of a Ni-Ni dumbbell oriented in the {l angle}111{r angle} direction with one or two adjacent antisite defects. The Fe interstitial in FeTi had a similar configuration, except the dumbbell contained Fe atoms. The Ti interstitial in FeTi formed an {l angle}110{r angle} Fe-Fe dumbbell. 8 refs., 2 tabs.

  11. Hydrolysis of TiCl₄: Initial Steps in the Production of TiO₂

    SciTech Connect

    Wang, Tsang-Hsiu; Navarrete-Lopez, Alejandra M.; Li, Shenggang; Dixon, David A.; Gole, James L.

    2010-06-24

    The hydrolysis of titanium tetrachloride (TiCl{sub 4}) to produce titanium dioxide (TiO{sub 2})nanoparticles has been studied to provide insight into the mechanism for forming these nanoparticles. We provide calculations of the potential energy surfaces, the thermochemistry of the intermediates, and the reaction paths for the initial steps in the hydrolysis of TiCl{sub 4}. We assess the role of the titanium oxychlorides (Ti{sub x}O{sub y}Cl{sub z}; x = 2-4, y = 1,3-6, and z = 2, 4, 6) and their viable reaction paths. Using transition-state theory and RRKM theory, we predicted rate constants including the effect of tunneling. Heats of formation at 0 and 298 K are predicted for TiCl{sub 4}, TiCl{sub 3}OH, TiOCl{sub 2}, TiOClOH, TiCl{sub 2}(OH){sub 2}, TiCl(OH){sub 3}, Ti(OH){sub 4}, and TiO{sub 2} using the CCSD(T) method with correlation consistent basis sets extrapolated to the complete basis set limit and compared with the available experimental data. Clustering energies and heats of formation are calculated for neutral clusters. The calculated heats of formation were used to study condensation reactions that eliminate HCl or H{sub 2}O. The reaction energy is substantially endothermic if more than two HCl molecules are eliminated. The results show that the mechanisms leading to formation of TiO{sub 2} nanoparticles and larger ones are complicated and will have a strong dependence on the experimental conditions.

  12. Elution of Ti during solvent extraction of coal and the transformation of eluted Ti upon combustion

    SciTech Connect

    Zhang, L.A.; Takanohashi, T.; Saito, I.; Wang, Q.Y.; Ninomiya, Y.

    2008-06-15

    Solvent extraction of coal is an effective method for removing coal ash, thereby generating the ultraclean fuel that can be directly combusted in gas turbine. Due to their organic affinity, a few inorganic elements can be extracted as well. Ti in coal extract, its elution from raw coal as well as the transformation of eluted Ti during coal extract combustion, have been investigated. Two coals of the U.S. and their acid-washed samples were extracted under 1 MPa N{sub 2} (cold) at 360{sup o}C. The solvents used include nonpolar 1-methylnaphthalene and its mixtures with polar indole. The results indicate that, Ti in coal extracts is mainly composed of nanoparticles including TiO{sub 2} (anatase) and Ti associated with quartz. These particles are insoluble in any acids, having a fine dispersion into coal matrix. Upon coal fragmentation at 360{sup o}C, they could be liberated, and, hence, traversed the filter for isolating coal extracts. The organo-Ti was preferentially extracted as well, which is most likely in a form of Ti porphyrin or Ti chelated with phenol-oxygen. These findings also have implications for revealing the modes of occurrence of Ti in the raw coals. Combustion of coal extract at 1,000{sup o}C resulted in the formation of nanometric TiO{sub 2} polymorphs and complex compounds like FeZnTiO{sub 4}. The former species could be mainly formed by the phase change of TiO{sub 2} (anatase) at high-temperatures, while formation of the latter one could involve the capture of metallic vapors like Zn on TiO{sub 2} polymorphs.

  13. Stress-induced martensitic transformations in NiTi and NiTi-TiC composites investigated by neutron diffraction

    SciTech Connect

    Vaidyanathan, R.; Bourke, M.A.M.; Dunand, D.C.

    1998-12-31

    Superelastic NiTi (51.0 at% Ni) with 0, 10 and 20 vol% TiC particles were deformed under uniaxial compression as neutron diffraction spectra were simultaneously obtained. The experiments yielded in-situ measurements of the thermoelastic stress-induced transformation. A detailed Rietveld determination is made of the phase fractions and the evolving strains in the reinforcing TiC particles and the austenite as it transforms to martensite on loading (and its subsequent back transformation on unloading). These strains are used to shed light on the phenomenon of load transfer in composites where the matrix undergoes a stress-induced phase transformation.

  14. Mechanical properties and microstructures of dental cast Ti-6Nb-4Cu, Ti-18Nb-2Cu, and Ti-24Nb-1Cu alloys.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo

    2016-01-01

    The mechanical properties -tensile strength, yield strength, elongation after fracture, and Vickers hardness- and alloy phases of the dental cast alloys Ti-6%Nb-4%Cu, Ti-18%Nb-2%Cu, and Ti-24%Nb-1%Cu were investigated. Ti-6%Nb-4%Cu consisted of a single α-phase, while Ti-18%Nb-2%Cu and Ti-24%Nb-1%Cu consisted of α- and β-phases. The tensile strengths, yield strengths, and hardnesses of these alloys were higher than those of Ti-5%Cu and Ti-30%Nb; however, their breaking elongations were smaller. These differences in the mechanical properties are attributable to solid-solution strengthening or to precipitation strengthening by the dual-phase (α+β) structure. Thus, Ti-Nb-Cu alloys are suitable for use in high-strength dental prostheses, such as implantretained superstructures and narrow-diameter implants. PMID:27477221

  15. The effect of site geometry, Ti content and Ti oxidation state on the Ti K-edge XANES spectrum of synthetic hibonite

    NASA Astrophysics Data System (ADS)

    Doyle, P. M.; Berry, A. J.; Schofield, P. F.; Mosselmans, J. F. W.

    2016-08-01

    The Al-rich oxide hibonite (CaAl12O19) is modeled to be the second mineral to condense from a gas of solar composition and is found within calcium-aluminum-rich inclusions and the matrix of chondritic meteorites. Both Ti3+ and Ti4+ are reported in meteoritic hibonite, so hibonite has been proposed as a single mineral oxybarometer that could be used to elucidate conditions within the first 0.2 Myrs of the Solar System. Synthetic hibonites with Ti3+/(Ti3+ + Ti4+) (hereafter Ti3+/ΣTi) ranging between 0 and 1 were prepared as matrix-matched standards for meteoritic hibonite. The largest yield of both Ti-free and Ti-bearing hibonite at ∼1300 and ∼1400 °C was obtained by a single sinter under reducing conditions. In situ micro-beam Ti K-edge X-ray absorption near edge structure (XANES) spectra were recorded from the synthetic hibonites, as well as from terrestrial hibonite. Spectral features in the post-crest region were shown to correlate with the Ti4+ content. Furthermore, Ti4+ on the M2 trigonal bipyramidal and the adjoining M4 octahedral sites appears to cause variability in the post-crest region as a function of orientation. For this suite of synthetic hibonites it was observed that the pre-edge peak region is not influenced by orientation, but is controlled by Ti3+/ΣTi, site geometry and/or Ti concentration. In particular, the pre-edge peak intensities reflect Ti coordination environment and distortion of the M4 octahedral site. Therefore, although pre-edge peak intensities have previously been used to determine Ti3+/ΣTi in meteoritic minerals, we excluded use of the pre-edge peak intensities for quantifying Ti valence states in hibonite. The energy of the absorption edge at a normalized intensity of 0.8 (E0.8) and the energy of the minimum between the pre-edge region and the absorption edge (Em1) were found to vary systematically with Ti3+/ΣTi. Ti3+/ΣTi in hibonite as a function of Em1 was modeled by a quadratic function that may be used to quantify Ti3

  16. Solid solution cermet: (Ti,Nb)(CN)-Ni cermet.

    PubMed

    Kwon, Hanjung; Jung, Sun-A

    2014-11-01

    Solid solution powders without W, (Ti,Nb)(CN) powders with a B1 structure (NaCl like), were synthesized by high energy milling and carbothermal reduction in nitrogen. The range of molar ratios of Ti/Nb for forming complete (Ti,Nb)(CN) phase was broader than that of Ti/W for the (Ti,W)(CN) phase because carbide or carbonitride of Nb had a B1 crystal structure identical to Ti(CN) while WC had a hexagonal crystal structure. The results revealed that the hardness of (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,W)(CN)-Ni cermets. The lower density of the (Ti,Nb)(CN) powder contributed to the higher hardness compared to (Ti,W)(CN) because the volumetric ratio of (Ti,Nb)(CN) in the (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,Nb)(CN) in the (Ti,W)(CN)-Ni cermets at the same weight ratio of Ni. Additionally, it was assumed that intrinsic the properties of (Ti,Nb)(CN) could also be the cause for the high hardness of the (Ti,Nb)(CN)-Ni cermets. PMID:25958611

  17. The permeation behavior of deuterium through 1Cr18Ni9Ti stainless steel with TiN+TiC-TiN multiple films

    SciTech Connect

    Xiong, Y.; Song, J.; Luo, D.; Lei, Q.; Chen, C.

    2015-03-15

    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 good 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.

  18. Using Ti-5111 for marine fastener applications

    NASA Astrophysics Data System (ADS)

    Been, J.; Faller, K.

    1999-06-01

    Titanium offers virtually unsurpassed resistance to crevice, pitting, and stress-corrosion cracking in seawater environments. Ti-5Al-1Sn-1Zr-1V-0.8Mo (Ti-5111) is a near-alpha titanium alloy of intermediate strength, excellent toughness, and roomtemperature creep resistance designed in a U.S. Navy-sponsored titanium alloy development program for structural submarine applications. Ti-5111’s desirable mechanical properties and excellent corrosion resistance render this titanium alloy an ideal fastener material from both a technical and economic perspective.

  19. In situ synthesis and hardness of TiC/Ti5Si3 composites on Ti-5Al-2.5Sn substrates by gas tungsten arc welding

    NASA Astrophysics Data System (ADS)

    Yan, Wen-qing; Dai, Le; Gui, Chi-bin

    2013-03-01

    TiC/Ti5Si3 composites were fabricated on Ti-5Al-2.5Sn substrates by gas tungsten arc welding (GTAW). Identification of the phases was performed using X-ray diffraction (XRD). The microstructures were analyzed using scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectrometry (EDS) and optical microscopy (OM). The Vickers hardness was measured with a micro-hardness tester. The TiC/Ti5Si3 composites were obtained in a double-layer track, and the Vickers hardness of the track increased by two to three times compared with the Ti-5Al-2.5Sn substrate.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  1. Pulsed Current Activated Synthesis and Consolidation of Nanostructured Ti-TiC Composite and Its Mechanical Properties.

    PubMed

    Kim, Dong-Ki; Park, Na-Ra; Kim, Byung-Su; Yoon, Jin-Kook; Hong, Kyung-Tae; Shon, In-Jin

    2016-02-01

    Ti and CNT powders were milled by high energy ball milling. The milled powders were then simultaneously synthesized and consolidated using pulsed current activated sintering (PCAS) within one minute under the applied pressure of 80 MPa. The advantage of this process is not only rapid densification to near theoretical density but also to prevent grain growth in nano-structured materials The milling did not induce any reaction between the constituent powders. Meanwhile, PCAS of the Ti-CNT mixture produced a Ti-TiC composite according to the reaction (Ti + 0.06CNT --> 0.94Ti+0.06TiC, Ti+0.12CNT --> 0.88Ti+0.12TiC). Highly dense nanocrystalline Ti-TiC compos- ites with a relative density of up to 99.5% were obtained within one minute. The hardness and fracture toughness of the dense Ti-6mole% TiC and Ti-12 mole% TiC produced by PCAS were also investigated. PMID:27433696

  2. LASE Ti:Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Dr. Larry B. Petway (Science Applications International Corp.) is making final adjustments to the Ti:Sapphire Laser in preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for intergration into a NASA/ER-2 aircraft. LASE is the first fully- engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE.Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  3. Ti-in-Zircon Thermometer: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Fu, B.; Cavosie, A. J.; Clechenko, C. C.; Fournelle, J.; Kita, N. T.; Lackey, J.; Page, F.; Wilde, S. A.; Valley, J. W.

    2005-12-01

    The titanium in zircon thermometer has been applied to 167 zircons from diverse rock types. These rocks include metamorphosed anorthosite and gabbro (1.15 Ga, intrusion age), and unmetamorphosed granitic pegmatite (0.9 Ga) from the Adirondack Highlands; metaluminous and peraluminous granites (114-90 Ma) of the Sierra Nevada Batholith; megacrysts from kimberlite pipes in southern Africa, Brazil, and Siberia; and detrital zircons (4.4-3.9 Ga) of metaconglomerate from Jack Hills, Western Australia. Titanium concentration in zircon was analysed using a CAMECA IMS-1280 ion microprobe (see Page et al., this volume). Spot analyses were correlated to U-Pb SHRIMP pits especially for Adirondack and Jack Hills zircons. The majority of zircons have Ti-content less than 10 ppm. Variability, in excess of analytical precision, within individual zircons is observed in about one-third of crystals. In general, there is no systematic change in Ti from core to rim (identified by cathodoluminescence) of zircons, or with regard to age, U content, Th/U ratio, or U-Pb age concordance for these non-metamict grains. The average temperatures for zircon crystallization in different rock suites using the experimental/empirical calibration of Watson and Harrison (W&H, 2005, Science 308:841), assuming the presence of rutile and quartz, are estimated to be: anorthosite 735±41°C (1SD, n=24; Ti = 10±5 ppm); metagabbro 714±31°C (n=19; Ti = 8±4 ppm); Adirondack pegmatite 500±16°C (n=5; Ti = 0.3±0.1 ppm); metaluminous and peraluminous granites from Sierra Nevada 681±67°C (n=53; Ti = 6±5 ppm) and 613±75°C (n=68; Ti = 3±3 ppm); kimberlite megacrysts 740±64°C (n=169; Ti = 14±13 ppm) (Page et al., this volume); and detrital zircons from Jack Hills metaconglomerate 718±63°C (n=64; Ti = 10±9 ppm). Most of the host rocks contain ilmenite or titanite suggesting that α(TiO2)>0.5, but rutile activity is unknown for megacrysts and detrital zircons. Pegmatite contains no Ti-rich minerals

  4. A novel, layered phase in Ti-rich SrTiO3 epitaxial thin films.

    PubMed

    Lee, Sungki; Damodaran, Anoop R; Gorai, Prashun; Oh, Nuri; Moyer, Jarrett A; Kwon, Ji-Hwan; Ferdous, Naheed; Shah, Amish; Chen, Zuhuang; Breckenfeld, Eric; Mangalam, R V K; Braun, Paul V; Schiffer, Peter; Shim, Moonsub; Zuo, Jian-Min; Ertekin, Elif; Martin, Lane W

    2015-02-01

    Sr2Ti7O14, a new phase, is synthesized by leveraging the innate chemical and thermo-dynamic instabilities in the SrTiO3-TiO2 system and non-equilibrium growth techniques. The chemical composition, epitaxial relationships, and orientation play roles in the formation of this novel layered phase, which, in turn, possesses unusual charge ordering, anti-ferromagnetic ordering, and low, glass-like thermal conductivity. PMID:25523179

  5. 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)

  6. Ti-O-N/Ti composite coating on Ti-6Al-4V: surface characteristics, corrosion properties and cellular responses.

    PubMed

    Cao, Xiao-Lin; Sun, Tao; Yu, Yonghao

    2015-03-01

    To enhance the corrosion resistance of Ti-6Al-4V and extend its lifetime in medical applications, Ti-O-N/Ti composite coating was synthesized on the surface via plasma immersion ion implantation and deposition (PIIID). Surface morphology and cross sectional morphology of the composite coating were characterized using atomic force microscopy and scanning electron microscopy, respectively. Although X-ray photoelectron spectroscopic analysis revealed that the Ti-O-N/Ti composite coating was composed of non-stoichiometric titanium oxide, titanium nitride and titanium oxynitride, no obvious characteristic peak corresponding to the crystalline phases of them was detected in the X-ray diffraction pattern. In accordance with Owens-Wendt equation, surface free energy of the uncoated and coated samples was calculated and compared. Moreover, the corrosion behavior of uncoated and coated samples was evaluated by means of electrochemical impedance spectroscopy measurement, and an equivalent circuit deriving from Randles model was used to fit Bode plots and describe the electrochemical processes occurring at the sample/electrolyte interface. On the basis of the equivalent circuit model, the resistance of the composite coating was 4.7 times higher than that of the passive layer on uncoated samples, indicating the enhanced corrosion resistance after PIIID treatment. Compared to uncoated Ti-6Al-V, Ti-O-N/Ti-coated samples facilitated ostoblast proliferation within 7 days of cell culture, while there was no statistically significant difference in alkaline phosphate activity between uncoated and coated samples during 21 days of cell culture. PMID:25737126

  7. HYDROGEN ADSORPTION ON β-TiAl (001) AND Ni/TiAl (001) SURFACES

    NASA Astrophysics Data System (ADS)

    Mubarak, A. A. Karim; Alelaimi, Mahmoud

    2014-04-01

    In this paper, we present first principles calculations of the energetic, electronic and magnetic properties of the variant termination of TiAl (001) and Ni/TiAl (001) surfaces with and without hydrogen atoms. The calculations have been performed within the density functional theory using full-potential linearized augmented plane wave method. The generalized gradient approximation (GGA) is utilized as the exchange-correlation energy. The octahedral site is the stable absorption site of H atom in the β-TiAl system. This absorption reduces the cohesive energy of β-TiAl system due to increase in the lattice constant. The surface energy for both TiAl (001) terminations is calculated. The stable adsorption site of H atoms on the variant termination of TiAl (001) surface is performed. The adsorption energy of hydrogen on Ti is more energetic than that on Al. The adsorption of H atom on both terminations of H/Ni/TiAl (001) is more preferable at the bridge site. The adsorption energies are enhanced on Ni atom due to the contraction between d-Ni bands and TiAl substrate band.

  8. 40Ca(α,γ)44Ti and the production of 44Ti in supernovae

    NASA Astrophysics Data System (ADS)

    Vockenhuber, C.; Ouellet, C. O.; The, L.-S.; Buchmann, L.; Caggiano, J.; Chen, A. A.; D'Auria, J. M.; Davids, B.; Fogarty, L.; Frekers, D.; Hussein, A.; Hutcheon, D. A.; Kutschera, W.; Ottewell, D.; Paul, M.; Pavan, M. M.; Pearson, J.; Ruiz, C.; Ruprecht, G.; Trinczek, M.; Wallner, A.

    2008-01-01

    The nuclide 44Ti is predicted to be produced in significant quantities in core-collapse supernovae, and indeed it has been observed in the supernova remnant Cassiopeia-A by space-based γ-ray telescopes. The main production of 44Ti takes place in the α-rich freeze-out phase deep inside the supernova. The key reactions governing the 44Ti abundance have been identified in an earlier sensitivity study. Using the recoil mass spectrometer DRAGON at the TRIUMF-ISAC facility in Vancouver, Canada, we measured the main production reaction 40Ca(α,γ)44Ti, resulting in an increased reaction rate compared to the rate derived from previous prompt γ-ray studies, which is commonly used in supernova models. The uncertainty of the 44Ti production is now dominated by the rate of reactions with short-lived nuclides around 44Ti, namely 45V(p,γ)46Cr, 44Ti(α,p)47V and 44Ti(α,γ)48Cr. The sensitivity of these reactions on the 44Ti production has been revisited.

  9. Preparing and internal friction of VOx/TiOx/Ti multilayer thin films

    NASA Astrophysics Data System (ADS)

    Li, H. Q.; He, X. X.; Fang, G. Z.; Shao, L. F.

    2009-11-01

    VOx/TiOx/Ti multilayer thin films were deposited on glass and molybdenum substrates by magnetron reactive sputtering. The structure and properties of thin films were measured with X-ray diffraction (XRD), QJ31 Wheatstone Bridge and the internal friction instrument. Preparing process and internal friction of VOx/TiOx/Ti multilayer thin films were studied respectively. On the basis of measurement analysis from crystal structure, the curves of resistance vs temperature, and Young's modulus vs temperature, the phase transformation of VOx multilayer thin film occurs at 66°C and its temperature coefficient of resistance is - 4.35%/°C.

  10. Electron cyclotron resonance plasma etching of native TiO{sub 2} on TiN

    SciTech Connect

    Day, M.E.; Delfino, M.

    1996-01-01

    Thin-film polycrystalline Tin with an approximate 2 nm thick native TiO{sub 2} overlayer is bombarded with 50 to 200 eV Ar ions in an electron cyclotron resonance plasma. In situ X-ray photoelectron spectroscopy and static secondary ion mass spectrometry suggest complete removal of oxygen from the planar surface, independent of ion energy, with TiO{sub 2} remaining on the columnar grain boundaries. The TiN etching rate increases from 6 to 14 nm/min as the ion energy is raised from 100 to 200 eV. The TiN stoichiometry does not change with ion bombardment.

  11. Laser surface modification of Ti and TiC coatings on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Kim, J. M.; Lee, S. G.; Park, J. S.; Kim, H. G.

    2014-12-01

    In order to enhance the surface properties of magnesium alloy, a highly intense laser surface melting process following plasma spraying of Ti or TiC on AZ31 alloy were employed. When laser surface melting was applied to Ti coated magnesium alloy, the formation of fine Ti particle dispersed surface layer on the substrate occurred. The corrosion potential of the AZ31 alloy with Ti dispersed surface was significantly increased in 3.5 wt % NaCl solution. Additionally, an improved hardness was observed for the laser treated specimens as compared to the untreated AZ31 alloy. Laser melting process following plasma thermal deposition was also applied for obtaining in situ TiC coating layer on AZ31 alloy. The TiC coating layer could be successfully formed via in situ reaction between pure titanium and carbon powders. Incomplete TiC formation was observed in the plasma sprayed specimen, while completely transformed TiC layer was found after post laser melting process. It was also confirmed that the laser post treatment induced enhanced adhesion strength between the coating and the substrate.

  12. Synchrotron diffraction studies of TiC/FeTi cermets obtained by SHS

    SciTech Connect

    Contreras, L.; Turrillas, X.; Mas-Guindal, M.J.; Vaughan, G.B.M.; Kvick, A.; Rodriguez, M.A. . E-mail: mar@icv.csic.es

    2005-05-15

    TiC/FeTi composites have been obtained in situ by Self-propagating High-temperature Synthesis (SHS) of an intimate mixture of compacted powders of elemental carbon, titanium and iron. The reaction has been followed in real time by X-ray diffraction at the ESRF. The mechanism of the reaction is discussed in terms of the formation of a liquid phase corresponding to the eutectic of the Fe/Ti system prior to the TiC synthesis. Temperatures of reaction have been estimated by correlating thermal expansion coefficients with diffraction peaks shifts. The microstructures obtained by this method, suitable for cutting tools and wear resistant applications, are presented.

  13. Microstructure and mechanical properties of ceramic coatings on Ti and Ti-based alloy

    NASA Astrophysics Data System (ADS)

    Surowska, B.; Bieniaś, J.; Walczak, M.; Sangwal, K.; Stoch, A.

    2004-11-01

    Results of a study of silica and silica-titania sol-gel coatings for the creation of intermediate interfaces between commercially pure Ti or titanium alloy Ti6Al4VELI and dental porcelain are presented. Coatings of SiO2 on Ti6Al4V alloy and SiO2-TiO2 on Ti were deposited using sol-gel method. Surface microstructures and wear behaviour of the coatings were studied by using scanning electron microscopy with electron diffraction spectroscopy and pin-on-disc method. It is found that (1) Ti6Al4V/SiO2 and Ti/SiO2-TiO2 coatings obtained by the sol-gel method are compact, chemically homogeneous and relatively rough, and (2) the smaller wear of SiO2 coatings than that of SiO2-TiO2 coatings is associated with differences in their microstructure and roughness.

  14. Effect of water absorption of dielectric underlayers on crystal orientation in Al-Si-Cu/Ti/TiN/Ti metallization

    NASA Astrophysics Data System (ADS)

    Yoshida, Tomoyuki; Hashimoto, Shoji; Hosokawa, Hideki; Ohwaki, Takeshi; Mitsushima, Yasuichi; Taga, Yasunori

    1997-05-01

    The influence of the exposure of underlying dielectric (phophosilicate glass and borophosphosilicate glass) films to a humid air ambient on crystallographic orientations in Al-Si-Cu/Ti/TiN/Ti layered structures has been investigated as a function of the boron content and exposure time of the dielectric films. The Al(111) orientation in the layered structures was found to improve drastically with increasing boron content and exposure time of the dielectric films. The full width at half maximum value of an Al(111) x-ray rocking curve reached less than 1°. It was also found that the Al-Si-Cu surface becomes smoother and the average grain size increases as the Al(111) orientation improves. The improved Al(111) orientation was attributed to the improved Ti(002) orientation of the bottom Ti films. The mechanism of the improved Ti(002) orientation was investigated. It was confirmed that the improved orientation is closely related with the surface concentration of the absorbed water in the dielectric films. Further, it was demonstrated that interconnects fabricated from the improved layered structure have excellent electromigration performance.

  15. Microstructure and corrosion behavior of TiC/Ti(CN)/TiN multilayer CVD coatings on high strength steels

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Xue, Qi; Li, Songxia

    2013-09-01

    Titanium carbide/titanium carbonitride/titanium nitride (TiC/Ti(CN)/TiN) multilayer coatings are prepared on the surface of three high-strength steels (35CrMo, 42CrMo, and 40CrNiMo) by chemical vapor deposition method. The fracture morphology, elemental distribution, phase composition, micro-hardness, and adhesion of the multilayer film are analyzed. The hydrogen sulfide stress corrosion resistance of the coating is evaluated by the National Association of Corrosion Engineers saturated hydrogen sulfide solution immersion test. A test simulating the environment of the natural gas wells with high temperature and pressure in Luojiazhai in Sichuan is also performed. The results show that the multilayer coatings have dense structures, ∼11 μm thickness, 24.5 ± 2.0 GPa nano-hardness, and ∼70 N adhesion. The corrosion sample also shows no brittle failure induced by stress corrosion after treatment with the coating. Gravimetric analysis shows that the deposition of TiC/Ti(CN)/TiN multilayer coatings results in a corrosion rate reduction of at least 50 times compared with the high-strength steel substrate. A preliminary analysis on this phenomenon is conducted.

  16. Formation of TiO2 layers on commercially pure Ti and Ti-Mo and Ti-Nb alloys by two-step thermal oxidation and their photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sado, Shota; Ueda, Takatoshi; Ueda, Kyosuke; Narushima, Takayuki

    2015-12-01

    Anatase-containing TiO2 layers were formed on commercially pure (CP) Ti and Ti-25mass%Mo (Ti-25Mo) and Ti-25mass%Nb (Ti-25Nb) alloys by two-step thermal oxidation. The first-step treatment was conducted in an Ar-1%CO atmosphere at 1073 K for 3.6 ks, and the second-step treatment was conducted in air at 673-1073 K for 10.8 ks. The second-step temperature range for anatase formation was wider in the Ti alloys than in CP Ti. Photo-induced superhydrophilicity under UV irradiation was observed for the TiO2 layers with anatase fractions ≥0.6 on CP Ti and the Ti-25Mo alloy, and with anatase fractions ≥0.18 on the Ti-25Nb alloy. The TiO2 layers on the Ti-25Nb alloy exhibited excellent photocatalytic activity in the low anatase fraction region, which is considered to be caused by the incorporation of 1-3 at% Nb into the TiO2 layers. The rate constant of methylene blue degradation showed maxima at anatase fractions of 0.6-0.9.

  17. Corrosion and cell adhesion behavior of TiN-coated and ion-nitrided titanium for dental applications

    NASA Astrophysics Data System (ADS)

    Huang, Her-Hsiung; Hsu, Chu-Hui; Pan, Szu-Jung; He, Ju-Liang; Chen, Chun-Cheng; Lee, Tien-Ling

    2005-05-01

    This study investigated the corrosion resistance and cell adhesion behavior of titanium nitride (TiN)-coated and ion-nitrided Ti substrates for dental applications. The TiN-coated specimen surface layer contained a TiN/Ti structure, while the ion-nitrided specimen contained a Ti 2N/TiN/Ti structure. The polarization curves in artificial saliva showed that the corrosion rate and passive current for the specimens ranked as: untreated Ti > ion-nitrided Ti > TiN-coated Ti. The polarization resistance obtained from the electrochemical impedance spectroscopy ranked as: TiN-coated Ti > ion-nitrided Ti > untreated Ti. After 24 h osteoblast-like U-2 OS cell incubation on the specimens, the attached cell number occurred in the order: TiN-coated Ti > ion-nitrided Ti > untreated Ti. The TiN-coating and ion-nitriding treatments can improve the corrosion resistance and cell adhesion behavior of Ti.

  18. Itinerant antiferromagnetism of TiAl alloys

    NASA Astrophysics Data System (ADS)

    Petrişor, T.; Pop, I.; Giurgiu, A.; Farbaş, N.

    1986-06-01

    Magnetic susceptibility measurements of TiAl alloys are reported. Aluminium, by alloying, acts on the Néel temperature of pure titanium giving rise to a complicated phase diagram. A theoretical model, based on the itinerant antiferromagnetism model of chromium is proposed in order to explain the magnetic phase diagram of TiAl alloys. The experimental and theoretical magnetic phase diagram are in good agreement.

  19. Experimental and numerical evaluations of adhesion strength and stress in TiN films deposited on ti-implanted aluminum

    SciTech Connect

    Xu Ming; Liu Youming; Li Liuhe; Cai Xun; Chen Qiulong; Chu, Paul K.

    2006-03-15

    Titanium ions were implanted into aluminum substrates at 40 kV prior to magnetron sputtering deposition of the Ti interlayer and TiN film using our custom-designed multifunctional ion implanter without breaking vacuum. An 82-nm-thick modified layer was formed between the TiN film and the substrate. The characteristics of the implanted samples were compared to those of TiN/Al and TiN/Ti/Al samples that were not preimplanted. Based on our scratch tests, the critical loading L{sub c} of the TiN/Ti/Ti-implanted Al sample was significantly improved compared to the unimplanted TiN/Al and TiN/Ti/Al samples. Finite element analysis was conducted to simulate the scratch process to help reveal the stress distributions in the vicinity of the interlayer. The results show that the stress around the interface is largely reduced in the TiN/Ti/Ti-implanted Al sample. Consequently, the mechanical properties such as resistance to loadings are enhanced.

  20. Calculation of the Ti(C y N1- y )-Ti4C2S2-MnS-austenite equilibrium in Ti-bearing steels

    NASA Astrophysics Data System (ADS)

    Liu, W. J.; Jonas, J. J.

    1989-08-01

    A thermodynamic model is presented for the equilibria among various precipitates (Ti(C y N1- y ), Ti4C2S2, and MnS) and austenite containing six alloying elements (C, Mn, N, S, Si, and Ti). This model is applied to four microalloyed steels with Ti levels of 0.05, 0.11, 0.18, and 0.25 pct. The calculations show that the Ti in these steels cannot be completely dissolved over the austenite temperature range. However, the compositions of the undissolved Ti carbonitrides differ significantly from pure TiN, as 10 to 40 pct of the nitrogen is replaced by carbon. An expression for the Gibbs energy for the formation of Ti4C2S2 in austenite is estimated. The present predictions are compared with those of the Hudd, Jones, and Kale (HJK) model; considerable differences are observed at temperatures below 1250°C.

  1. Instability of hydrogenated TiO2.

    PubMed

    Nandasiri, Manjula I; Shutthanandan, Vaithiyalingam; Manandhar, Sandeep; Schwarz, Ashleigh M; Oxenford, Lucas; Kennedy, John V; Thevuthasan, Suntharampillai; Henderson, Michael A

    2015-11-19

    Hydrogenated TiO2 (H-TiO2) is touted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using nuclear reaction analysis (NRA), Rutherford backscattering spectrometry, ultraviolet photoelectron spectroscopy, and X-ray photoelectron spectroscopy. Protons (40 keV) implanted at a ∼2 atom % level within a ∼120 nm wide profile of rutile TiO2(110) were situated ∼300 nm below the surface. NRA revealed that this H-profile broadened toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (∼800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile at low temperatures, as well as its interfacial activity toward reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. PMID:26545303

  2. Instability of Hydrogenated TiO2

    SciTech Connect

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  3. Synthesis and structural study of Ti-rich Mg-Ti hydrides

    SciTech Connect

    Asano, Kohta; Kim, Hyunjeong; Sakaki, Kouji; Page, Katharine; Hayashi, Shigenobu; Nakamura, Yumiko; Akiba, Etsuo

    2014-02-26

    MgxTi1-x (x = 0.15, 0.25, 0.35) alloys were synthesized by means of ball milling. Under a hydrogen pressure of 8 MPa at 423 K these Mg–Ti alloys formed a hydride phase with a face centered cubic (FCC) structure. The hydride for x = 0.25 consisted of single Mg0.25Ti0.75H1.62 FCC phase but TiH2 and MgH2 phases were also formed in the hydrides for x = 0.15 and 0.35, respectively. X-ray diffraction patterns and the atomic pair distribution function indicated that numbers of stacking faults were introduced. There was no sign of segregation between Mg and Ti in Mg0.25Ti0.75H1.62. Electronic structure of Mg0.25Ti0.75H1.62 was different from those of MgH2 and TiH2, which was demonstrated by 1H nuclear magnetic resonance. This strongly suggested that stable Mg–Ti hydride phase was formed in the metal composition of Mg0.25Ti0.75 without disproportion into MgH2 and TiH2.

  4. Porous TiO2 Assembled from Monodispersed Nanoparticles.

    PubMed

    Liu, Xu; Duan, Weijie; Chen, Yan; Jiao, Shihui; Zhao, Yue; Kang, Yutang; Li, Lu; Fang, Zhenxing; Xu, Wei; Pang, Guangsheng

    2016-12-01

    Porous TiO2 were assembled by evaporating or refluxing TiO2 colloid, which was obtained by dispersing the TiO2 nanoparticles with a crystallite size (d XRD) of 3.2 nm into water or ethanol without any additives. Porous transparent bulk TiO2 was obtained by evaporating the TiO2-C2H5OH colloid at room temperature for 2 weeks, while porous TiO2 nanospheres were assembled by refluxing the TiO2-H2O colloid at 80 °C for 36 h. Both of the porous TiO2 architectures were pore-size-adjustable depending on the further treating temperature. Porous TiO2 nanospheres exhibited enhanced photocatalysis activity compared to the nanoparticles. PMID:27000026

  5. Cermet with Slow TiC Coarsening During Sintering

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Ming; Tsai, Che-Wei; Huang, Sheng-Min; Yang, Chih-Chao; Yeh, Jien-Wei

    2014-10-01

    New TiC/Co1.5CrFeNi1.5Ti0.5 cermet was developed by exploiting the advantages of the high-entropy alloy (HEA) binder. A much finer grain structure and thus improved hardness-toughness combination were obtained as compared with two traditional binders, Ni and Ni13Mo7. From the coarsening behavior of TiC grains, the coarsening process of TiC in these three binders is diffusion-controlled. The activation energy of TiC + 20%Co1.5CrFeNi1.5Ti0.5 is the highest and that of TiC + 20%Ni is the lowest. The high activation energy of the Co1.5CrFeNi1.5Ti0.5 binder was attributable to its high content of carbon-strong-binding elements, Cr and Ti, and cooperative diffusion and higher packing density of multiple different-sized atoms. Low diffusion coefficient, low surface energy of TiC grains, and low solubility of Ti in the HEA liquid explain the slow coarsening of TiC grains. This study demonstrates that Co1.5CrFeNi1.5Ti0.5 is an excellent HEA binder for TiC cermets.

  6. 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

    2016-01-01

    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

  7. Hierarchical fabrication of heterojunctioned SrTiO3/TiO2 nanotubes on 3D microporous Ti substrate with enhanced photocatalytic activity and adhesive strength

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Yin, Lu; Zha, Kang; Li, Huirong; Liu, Zhiyuan; Wang, Jianxin; Duan, Ke; Feng, Bo

    2016-03-01

    Recently, construction of three-dimensional (3D) architecture and design of heterostructure have been proved to be two important approaches for improving photocatalytic (PC) properties of TiO2-based catalysts. In this work, a 3D microporous surface on Ti substrate (MPT) was prepared by simple acid etching. Then, heterojunctioned SrTiO3/TiO2 nanotubes with dominant {001} facets of anatase TiO2were successfully fabricated on MPT by combining anodization with hydrothermal treatment. The 3D microporous-patterned SrTiO3/TiO2 nanotubes heterojunction shows significantly enhanced photo-current density and ∼200% improved PC effect in degradation of Rhodamine B owing to its higher specific surface area, stronger light-harvesting ability and positive heterojunction effect in comparison with TiO2 nanotubes formed on flat Ti substrate. Moreover, the 3D microporous structure on Ti substrate improved the adhesive strength between the nanotubes layer and Ti substrate, which can be ascribed to the effective release of internal stress. Therefore, this present strategy is expected to expand the application of TiO2-based catalysts in many fields which require excellent PC properties and mechanical stability.

  8. Piezoelectric and Dielectric Properties of Multilayered BaTiO3/(Ba,Ca)TiO3/CaTiO3 Thin Films.

    PubMed

    Zhu, Xiao Na; Gao, Ting Ting; Xu, Xing; Liang, Wei Zheng; Lin, Yuan; Chen, Chonglin; Chen, Xiang Ming

    2016-08-31

    Highly oriented multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films were fabricated on Nb-doped (001) SrTiO3 (Nb:STO) substrates by pulsed laser deposition. The configurations of multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films are designed with the thickness ratio of 1:1:1 and 2:1:1 and total thickness ∼300 nm. Microstructural characterization by X-ray diffraction indicates that the as-deposited thin films are highly c-axis oriented and large in-plane strain is determined in BaTiO3 and CaTiO3 layers. Piezoresponse force microscopy (PFM) studies reveal an intense in-plane polarization component, whereas the out-of-plane shows inferior phase contrast. The optimized combination is found to be the BaTiO3-(Ba0.85Ca0.15)TiO3-CaTiO3 structure with combination ratio 2:1:1, which displays the largest domain switching amplitude under DC electric field, the largest room-temperature dielectric constant ∼646, a small dielectric loss of 0.03, and the largest dielectric tunability of ∼50% at 400 kV/cm. These results suggest that the enhanced dielectric and tunability performance are greatly associated with the large in-plane polarization component and domain switching. PMID:27514235

  9. Effect of Ti3+ on TiO2-supported Cu catalysts used for CO oxidation.

    PubMed

    Chen, Ching S; Chen, Tse C; Chen, Chen C; Lai, Yuan T; You, Jiann H; Chou, Te M; Chen, Ching H; Lee, Jyh-Fu

    2012-07-01

    In this paper, we have shown that Cu/TiO(2) catalysts are highly active in CO oxidation. For instance, a 3.4% Cu/TiO(2) catalyst exhibits a higher turnover rate for the effective removal of CO in air than 3-5% Pt/TiO(2) and 20% Cu/ZnO/Al(2)O(3) catalysts. A small amount of Cu(+) species is formed during the calcination treatment at 225 °C, which is the main active phase for the CO oxidation. However, it is proposed that some highly dispersed CuO can also form in the TiO(2) lattice during the calcination treatment. Furthermore, a strong electron interaction between Cu(2+) in highly dispersed CuO and Ti(3+) on rutile TiO(2) (Cu(2+)+Ti(3+)→Cu(+)+Ti(4+)) has been shown to occur. Overall, the reduction of Cu(+) is a major factor that contributes to the reaction rate of the CO oxidation. PMID:22676402

  10. A new, energy-efficient chemical pathway for extracting Ti metal from Ti minerals.

    PubMed

    Fang, Zhigang Zak; Middlemas, Scott; Guo, Jun; Fan, Peng

    2013-12-11

    Titanium is the ninth most abundant element, fourth among common metals, in the Earth's crust. Apart from some high-value applications in, e.g., the aerospace, biomedicine, and defense industries, the use of titanium in industrial or civilian applications has been extremely limited because of its high embodied energy and high cost. However, employing titanium would significantly reduce energy consumption of mechanical systems such as civilian transportation vehicles, which would have a profound impact on the sustainability of a global economy and the society of the future. The root cause of the high cost of titanium is its very strong affinity for oxygen. Conventional methods for Ti extraction involve several energy-intensive processes, including upgrading ilmenite ore to Ti-slag and then to synthetic rutile, high-temperature carbo-chlorination to produce TiCl4, and batch reduction of TiCl4 using Mg or Na (Kroll or Hunter process). This Communication describes a novel chemical pathway for extracting titanium metal from the upgraded titanium minerals (Ti-slag) with 60% less energy consumption than conventional methods. The new method involves direct reduction of Ti-slag using magnesium hydride, forming titanium hydride, which is subsequently purified by a series of chemical leaching steps. By directly reducing Ti-slag in the first step, Ti is chemically separated from impurities without using high-temperature processes. PMID:24256474

  11. Pure rotational spectra of TiO and TiO2 in VY Canis Majoris

    NASA Astrophysics Data System (ADS)

    Kamiński, T.; Gottlieb, C. A.; Menten, K. M.; Patel, N. A.; Young, K. H.; Brünken, S.; Müller, H. S. P.; McCarthy, M. C.; Winters, J. M.; Decin, L.

    2013-03-01

    We report the first detection of pure rotational transitions of TiO and TiO2 at (sub-)millimeter wavelengths towards the red supergiant VY CMa. A rotational temperature, Trot, of about 250 K was derived for TiO2. Although Trot was not well constrained for TiO, it is likely somewhat higher than that of TiO2. The detection of the Ti oxides confirms that they are formed in the circumstellar envelopes of cool oxygen-rich stars and may be the "seeds" of inorganic-dust formation, but alternative explanations for our observation of TiO and TiO2 in the cooler regions of the envelope cannot be ruled out at this time. The observations suggest that a significant fraction of the oxides is not converted to dust, but instead remains in the gas phase throughout the outflow. Based on observations carried out with the Submillimeter Array and IRAM Plateau de Bure Interferometer.Plateau de Bure data (FITS file) is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A113

  12. Tensile strength and elongation of laser-welded Ti and Ti-6AL-7NB.

    PubMed

    Watanabe, Ikuya; Topham, D Scott

    2004-10-15

    This study established data demonstrating the possible laser-welded strengths of cast Ti and Ti-6Al-7Nb and compared them to those of two dental-casting alloys. Cast plates of Ti, Ti-6Al-7Nb, gold, and Co-Cr alloy were prepared. After polishing the surfaces to be welded, two plates were abutted and welded using an Nd:YAG laser at a pulse duration of 10 ms, spot diameter of 1 mm, and voltage of 200 V. Five specimens were prepared for each metal by welding either three or five spots unilaterally or bilaterally. The fracture load and percent elongation were measured at a crosshead speed of 1.0 mm/min. The bilaterally welded specimens performed significantly greater than unilaterally welded specimens in both fracture load and elongation whether they were welded with three or five spots per side. The bilaterally welded Ti and Ti-6Al-7Nb specimens were nearly as strong as their corresponding control specimens, whereas the gold and Co-Cr specimens were approximately half as strong. When a large proportion of the cross-sectional area of the joint is laser welded, the strength of the laser-welded portion of the cast Ti and Ti-6Al-7Nb may approach or equal that of the nonwelded metal frameworks. PMID:15368227

  13. Effects of Ti additives on structural and electric properties of Cr- and Ti-codoped ZnO layers

    NASA Astrophysics Data System (ADS)

    Lee, Sejoon; Lee, Youngmin; Young Kim, Deuk; Won Kang, Tae

    2013-08-01

    We investigate the effects of Ti-codoping on the structural and electrical properties of the ZnCrTiO layers grown on the Pt (111)/Ti/Al2O3 (0001) substrates by co-sputtering of ZnCrO and Ti. The ZnCrTiO layers with the Ti contents of 0.2-0.3 at. % reveal the enhanced disorder-activated Raman modes, attributing to increased lattice-displacement-induced phonon scattering due to the incorporation of Ti additives. In comparison with ZnCrO, the ZnCrTiO layers exhibit the improved ferroelectric properties with one order of magnitude-increased remnant polarization. This causes a polarization-dependent asymmetric hysteresis behavior in the Pt/ZnCrTiO/Pt top-to-bottom metal-ferroelectric-metal device, suggesting potential applications for two-terminal ferroelectric-tunneling resistive memories.

  14. High damping NiTi/Ti3Sn in situ composite with transformation-mediated plasticity

    SciTech Connect

    Zhang, Junsong; Liu, Yinong; Huan, Yong; Hao, Shijie; Jiang, Daqiang; Ren, Yang; Shao, Yang; Ru, Yadong; Wang, Zhongqiang; Cui, Lishan

    2014-11-01

    The concept of transformation-induced plasticity effect is introduced in this work to improve the plasticity of brittle intermetallic compound Ti3Sn, which is a potent high damping material. This concept is achieved in an in situ NiTi/Ti3Sn composite. The composite is composed of primary Ti3Sn phase and (NiTi + Ti3Sn) eutectic structure formed via hypereutectic solidification. The composite exhibits a high damping capacity of 0.075 (indexed by tan δ), a high ultimate compressive strength of 1350 MPa, and a large plasticity of 27.5%. In situ synchrotron high-energy X-ray diffraction measurements revealed clear evidence of the stress-induced martensitic transformation (B2 → B19) of the NiTi component during deformation. The strength of the composite mainly stems from the Ti3Sn, whereas the NiTi component is responsible for the excellent plasticity of the composite.

  15. Surface characterization of Ti and Ti (6 percent, Al-4 percent, V) metal powders and interaction with primer solutions

    NASA Technical Reports Server (NTRS)

    Siriwardane, R. V.; Wightman, J. P.

    1983-01-01

    The interaction of Ti and Ti 6-4 powders with water and primer solutions was investigated experimentally by measuring the heats of immersion. Similar comparative studies were made on anatase and rutile TiO2 powders. The surface oxide layers of Ti and Ti 6-4 cracked on heating in vacuum between 300 and 400 C as evidenced by high heats of immersion in both water and primer solutions. Polyimide and polyphenylquinoxaline interacted preferentially, compared with the solvents with both metal powders after outgassing at room temperature. The heats of immersion of Ti 6-4 in water, solvents, and primer solutions increased significantly after pretreatment of the powder by an alkaline etch and a phosphate-fluoride process. The TiO2 powders were not satisfactory models for the surface oxide layer on either Ti or Ti 6-4 powder.

  16. Mechanical and Tribological Properties of Cold-Sprayed Ti Coatings on Ti-6Al-4V Substrates

    NASA Astrophysics Data System (ADS)

    Khun, N. W.; Tan, A. W. Y.; Liu, E.

    2016-04-01

    A cold spray process was used to deposit titanium (Ti) coatings of different thicknesses on commercial Ti-6Al-4V (Ti64) substrates. The hardness of the Ti coatings was measured using a Vickers micro-indenter. It was found that the thicker Ti coatings had higher hardness probably due to the better uniformity and higher density of the coatings. The tribological results showed that the friction and wear of the Ti coatings tested against a steel ball under dry condition became lower with higher thickness probably due to the higher wear resistance of the thicker coatings associated with their higher hardness. The specific wear rates of all the Ti coatings were significantly lower than that of the Ti64 substrate as a result of the higher wear resistance of the Ti coatings associated with their cold-worked microstructures and the formation of high wear resistant oxide layers on their wear tracks during the wear testing.

  17. Forming compliance dominated memristive switching through interfacial reaction in Ti/TiO2/Au structure

    NASA Astrophysics Data System (ADS)

    Tang, Zhensen; Fang, Liang; Xu, Nuo; Liu, Rulin

    2015-11-01

    The effects of the forming compliance current (CC) on bipolar resistive switching (BRS) characteristics in Au/Ti/TiO2/Au memristive switches were investigated. After forming with a low CC, a typical BRS with an abrupt SET and negative differential resistance RESET behaviors were observed. In comparison, the sample formed with a high CC exhibited an abnormal BRS with stepwise SET and abrupt RESET transitions. The conduction mechanisms at a high resistance state and a low resistance state were analyzed, respectively. The impact of the forming compliance on the interfacial reaction between Ti and TiO2 was discussed. The Ti-induced interfacial layer played an important role of manipulating the oxygen vacancies, thus providing the possibility of affecting the switching behavior. A physical model based on a combination of the bulk and interfacial effects was proposed to explain our observations.

  18. Preparation of TiOxNy/TiN composites for photocatalytic hydrogen evolution under visible light.

    PubMed

    Yang, Tao; Li, Qun; Chang, Xiwang; Chou, Kuo-Chih; Hou, Xinmei

    2015-11-21

    TiOxNy/TiN heterojunction composites with tunable chamber structures were prepared through reduction and nitridation of organotitania obtained via solvothermal alcoholysis at 900 °C for 4 h in partially cracked NH3. Owing to the low synthesis temperature, TiOxNy/TiN duplicates the original structure of organotitania. It also demonstrates an outstanding activity toward hydrogen production as high as 34.9 μmol h(-1) g(-1), which is about 1.5 times higher than the highest value reported in the literature for the TiN material. The enhanced photoactivity can be ascribed to the heterojunction structure, which is beneficial for separating the photogenerated carriers in space. PMID:26451403

  19. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    NASA Astrophysics Data System (ADS)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  20. Formation mechanism of TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Yao, B. D.; Chan, Y. F.; Zhang, X. Y.; Zhang, W. F.; Yang, Z. Y.; Wang, N.

    2003-01-01

    Transmission electron microscopic observation showed that TiO2 nanotubes synthesized via a simple hydrothermal chemical process formed a crystalline structure with open-ended and multiwall morphologies. Unlike multiwalled carbon nanotubes, the TiO2 nanotube walls were not seamless. During alkali treatment, crystalline TiO2 raw material underwent delamination in the alkali solution to produce single-layer TiO2 sheets. TiO2 nanotubes were formed by rolling up the single-layer TiO2 sheets with a rolling-up vector of [001] and attracting other sheets to surround the tubes.

  1. Electrocatalytic activity of Pd-loaded Ti/TiO2 nanotubes cathode for TCE reduction in groundwater.

    PubMed

    Xie, Wenjing; Yuan, Songhu; Mao, Xuhui; Hu, Wei; Liao, Peng; Tong, Man; Alshawabkeh, Akram N

    2013-07-01

    A novel cathode, Pd loaded Ti/TiO2 nanotubes (Pd-Ti/TiO2NTs), is synthesized for the electrocatalytic reduction of trichloroethylene (TCE) in groundwater. Pd nanoparticles are successfully loaded on TiO2 nanotubes which grow on Ti plate via anodization. Using Pd-Ti/TiO2NTs as the cathode in an undivided electrolytic cell, TCE is efficiently and quantitatively transformed to ethane. Under conditions of 100 mA and pH 7, the removal efficiency of TCE (21 mg/L) is up to 91% within 120 min, following pseudo-first-order kinetics with the rate constant of 0.019 min(-1). Reduction rates increase from 0.007 to 0.019 min(-1) with increasing the current from 20 to 100 mA, slightly decrease in the presence of 10 mM chloride or bicarbonate, and decline with increasing the concentrations of sulfite or sulfide. O2 generated at the anode slightly influences TCE reduction. At low currents, TCE is mainly reduced by direct electron transfer on the Pd-Ti/TiO2NT cathode. However, the contribution of Pd-catalytic hydrodechlorination, an indirect reduction mechanism, becomes significant with increasing the current. Compared with other common cathodes, i.e., Ti-based mixed metal oxides, graphite and Pd/Ti, Pd-Ti/TiO2NTs cathode shows superior performance for TCE reduction. PMID:23726693

  2. Exploration of the nature of active Ti species in metallic Ti-doped NaAlH4.

    PubMed

    Wang, Ping; Kang, Xiang-Dong; Cheng, Hui-Ming

    2005-11-01

    Clarification of the nature of active Ti species has been a key challenge in developing Ti-doped NaAlH(4) as a potential hydrogen storage medium. Previously, it has been greatly hindered by the invisibility of Ti-containing species in conventional analysis techniques. In the present study, for the first time, the catalytically active Ti-containing species have been definitely identified by X-ray diffraction in the hydrides doped with metallic Ti. It was found that mechanical milling of a NaH/Al mixture or NaAlH(4) with metallic Ti powder resulted in the formation of nanocrystalline Ti hydrides. The variation of the preparation conditions during the doping process leads to a slight composition variation of the Ti hydrides. The catalytic enhancement arising upon doping the hydride with commercial TiH(2) was quite similar to that achieved in the hydrides doped with metallic Ti. Moreover, the cycling stability that was previously established in metallic Ti-doped hydrides was also observed in the hydrides doped with TiH(2). These results clearly demonstrate that the in situ formed Ti hydrides act as active species to catalyze the reversible dehydrogenation of NaAlH(4). The mechanism by which Ti hydrides catalyze the reversible de-/hydrogenation reactions of NaAlH(4) was discussed. PMID:16853602

  3. A facile in-situ hydrothermal synthesis of SrTiO3/TiO2 microsphere composite

    NASA Astrophysics Data System (ADS)

    Wang, Hongxing; Zhao, Wei; Zhang, Yubo; Zhang, Shimeng; Wang, Zihao; Zhao, Dan

    2016-06-01

    TiO2 was successfully used as sacrificed template to synthesise SrTiO3/TiO2 microsphere composite via an in-situ hydrothermal process. The diameter of SrTiO3/TiO2 microsphere was about 700 nm with the same size of the template, and all of the microspheres were in good dispersity. The optimized reaction parameters for the phase and morphology of the as-synthesized samples were investigated. The results showed the SrTiO3/TiO2 microsphere can be synthesized at 170 °C when the concentration of sodium hydroxide was 0.1 M. Lower hydrothermal temperature hampered the formation of the SrTiO3/TiO2 composite, the higher alkali concentration, however, will destroy the morphology of products. The formation mechanism of SrTiO3/TiO2 microsphere composite was proposed and the photocatalytic properties of the samples were characterized using methylene blue solution as the pollutant under the UV light irradiation. The results indicated the proper OH- concentration will provide a channel for Sr2+ to react with Ti4+ located in the template and form the SrTiO3/TiO2 composite, and those with micro-scaled spherical morphology exhibited good photocatalytic activities.

  4. Are 44Ti-producing supernovae exceptional?

    NASA Astrophysics Data System (ADS)

    The, L.-S.; Clayton, D. D.; Diehl, R.; Hartmann, D. H.; Iyudin, A. F.; Leising, M. D.; Meyer, B. S.; Motizuki, Y.; Schönfelder, V.

    2006-05-01

    According to standard models supernovae produce radioactive 44Ti, which should be visible in gamma-rays following decay to 44Ca for a few centuries. 44Ti production is believed to be the source of cosmic 44Ca, whose abundance is well established. Yet, gamma-ray telescopes have not seen the expected young remnants of core collapse events. The 44Ti mean life of τ ≃ 89 y and the Galactic supernova rate of ≃3/100 y imply ≃several detectable 44Ti gamma-ray sources, but only one is clearly seen, the 340-year-old Cas A SNR. Furthermore, supernovae which produce much 44Ti are expected to occur primarily in the inner part of the Galaxy, where young massive stars are most abundant. Because the Galaxy is transparent to gamma-rays, this should be the dominant location of expected gamma-ray sources. Yet the Cas A SNR as the only one source is located far from the inner Galaxy (at longitude 112°). We evaluate the surprising absence of detectable supernovae from the past three centuries. We discuss whether our understanding of SN explosions, their 44Ti yields, their spatial distributions, and statistical arguments can be stretched so that this apparent disagreement may be accommodated within reasonable expectations, or if we have to revise some or all of the above aspects to bring expectations in agreement with the observations. We conclude that either core collapse supernovae have been improbably rare in the Galaxy during the past few centuries, or 44Ti-producing supernovae are atypical supernovae. We also present a new argument based on 44Ca/40Ca ratios in mainstream SiC stardust grains that may cast doubt on massive-He-cap type I supernovae as the source of most galactic 44Ca.

  5. Laser Processed TiN Reinforced Ti6Al4V Composite Coatings

    PubMed Central

    Balla, Vamsi Krishna; Bhat, Abhimanyu; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    The purpose of this first generation investigation is to evaluate fabrication, in vitro cytotoxicity, cell-materials interactions and tribological performance of TiN particle reinforced Ti6Al4V composite coatings for potential wear resistant load bearing implant applications. The microstructural analysis of the composites was performed using scanning electron microscope and phase analysis was done with X-ray diffraction. In vitro cell-materials interactions, using human fetal osteoblast cell line, have been assessed on these composite coatings and compared with Ti6Al4V alloy control samples. The tribological performance of the coatings were evaluated, in simulated body fluids, up to 1000 m sliding distance under 10N normal load. The results show that the composite coatings contain distinct TiN particles embedded in α + β phase matrix. The average top surface hardness of Ti6Al4V alloy increased from 394 ± 8 HV to 1138 ± 61 HV with 40 wt.% TiN reinforcement. Among the composite coatings, the coatings reinforced with 40 wt. % TiN exhibited the highest wear resistance of 3.74 × 10-6 mm3/Nm, which is lower than the wear rate, 1.04 × 10-5 mm3/Nm, of laser processed CoCrMo alloy tested under identical experimental conditions. In vitro biocompatibility study showed that these composite coatings were non-toxic and provides superior cell-material interactions compared to Ti6Al4V control, as a result of their high surface energy. In summary, excellent in vitro wear resistance and biocompatibility of present laser processed TiN reinforced Ti6Al4V alloy composite coatings clearly show their potential as wear resistant contact surfaces for load bearing implant applications. PMID:22301169

  6. Partial crystallization of picritic melt and its applications for the genesis of high-Ti and low-Ti basalts

    NASA Astrophysics Data System (ADS)

    Yang, J.; WANG, C.; Jin, Z.; Jin, S.; Yan, S.

    2015-12-01

    Geochemical and petrological studies have revealed the existence of high-Ti and low-Ti basalts in large igneous provinces (LIPs). However the originate of these high-Ti and low-Ti magmas are still under debate. Several different mechanisms have been proposed: (1) the high-Ti basalts are formed by the melting of mantle plume containing recycled oceanic crust (Spandler et al., 2008) while low-Ti basalts are formed by the melting of subcontinental lithospheric mantle (Xiao et al., 2004); (2) both high-Ti and low-Ti basalts are from mantle plume source, but the production of high-Ti basalts are associated with the thick lithosphere while the low-Ti basalts are controlled by the thin lithosphere (Arndt et al., 1993); (3) they are derived from the different degrees of melting, with high-Ti basalts representing low degree of partial melting of mantle plume (Xu et al., 2004). The low Mg# (below 0.7) of high-Ti and low-Ti basalts provides that they are far away from direct melting of mantle peridotite. In addition, seismic data indicate unusually high seismic velocities bodies beneath the LIPs which explained by the fractionated cumulates from picritic magmas (Farnetani et al., 1996). Therefore, we believed that the crystallization differentiation process might play a more significant role in the genesis of high-Ti and low-Ti basalts.In order to investigate the generation of high-Ti and low-Ti basalts, a series of high pressure and high temperature partial crystallization experiments were performed at pressures of 1.5, 3.0 and 5.0 GPa and a temperature range of 1200-1700℃. The starting material is picrate glass with relative high TiO2 (2.7 wt %), which is synthesized according to the chemical composition of primary magmas of Emeishan LIP (Xu et al., 2001). The experimental results show that: (1) At a given pressure, the TiO2 content is decreased with increasing melt fraction; (2) At a given melt fraction, the TiO2 content of melts is increased with increasing pressure. On

  7. Half-life of {sup 44}Ti

    SciTech Connect

    Ahmad, I.; Kutschera, W.; Castagnoli, G.; Paul, M.

    1995-08-01

    The measurement of the {sup 44}Ti half-life, started 3 years ago, is still continuing. The goal of this measurement is to determine the half-life of {sup 44}Ti, which is {approximately}52 y, to a precision of {approximately}5%. An accurate value of this half-life is of interest to cosmologists who need it to determine the production of heavy elements in supernova. Three sets of samples - a pure 200-nCi {sup 44}Ti sample, a pure 300-nCi {sup 60}Co source, and a mixed {sup 44}Ti-{sup 60}Co source of similar strength - were prepared and their spectra are being measured with Ge spectrometers at Argonne, Torino and Jerusalem. Each sample is counted for a period of 2 days, at approximate intervals of 4 months. The room background is also measured for the same length of time. We hope to start data analysis at the end of summer and obtain a value for the {sup 44}Ti half-life.

  8. Microstructures and Mechanical Properties of Transient Liquid-Phase Diffusion-Bonded Ti3Al/TiAl Joints with TiZrCuNi Interlayer

    NASA Astrophysics Data System (ADS)

    Ren, H. S.; Xiong, H. P.; Pang, S. J.; Chen, B.; Wu, X.; Cheng, Y. Y.; Chen, B. Q.

    2016-04-01

    Transient liquid-phase diffusion bonding of Ti3Al-based alloy to TiAl intermetallics was conducted using Ti-13Zr-21Cu-9Ni (wt pct) interlayer foil. The joint microstructures were examined using a scanning electron microscope (SEM) equipped with an electron probe micro-analyzer (EPMA). The microhardness across the joint was measured and joint strengths were tested. The results show that the Ti3Al/TiAl joint mainly consists of Ti-rich phase, Ti2Al layer, α 2-Ti3Al band, and residual interlayer alloy dissolved with Al. The amount of residual interlayer at the central part of the joint is decreased with the increase of the bonding temperature, and meantime the Ti2Al and α 2-Ti3Al reaction bands close to the joined Ti3Al-based alloy become thickened gradually. Furthermore, the central part of the joint exhibits the maximum microhardness across the whole joint. The joints bonded at 1193 K (920 °C) for 600 seconds with a pressure of 2 MPa presented the maximum shear strength of 417 MPa at room temperature, and the strength of 234 MPa was maintained at 773 K (500 °C).

  9. Corrosion behavior of TiN, TiAlN, TiAlSiN-coated 316L stainless steel in simulated proton exchange membrane fuel cell environment

    NASA Astrophysics Data System (ADS)

    Nam, Nguyen Dang; Vaka, Mahesh; Tran Hung, Nguyen

    2014-12-01

    To gain high hardness, good thermal stability and corrosion resistance, multicomponent TiAlSiN coating has been developed using different deposition methods. In this study, the influence of Al and Si on the electrochemical properties of TiN-coated 316L stainless steel as bipolar plate (BP) materials has been investigated in simulated proton exchange membrane fuel cell environment. The deposited TiN, TiAlN and TiAlSiN possess high hardness of 23.9, 31.7, 35.0 GPa, respectively. The coating performance of the TiN coating is enhanced by Al and Si addition due to lower corrosion current density and higher Rcoating and Rct values. This result could be attributed to the formation of crystalline-refined TiN(200), which improves the surface roughness, surface resistance, corrosion performance, and decreased passive current density.

  10. N-TiO2 nanoparticles embedded in silica prepared by Ti ion implantation and annealing in nitrogen

    SciTech Connect

    Xiang, Xia; Chen, Meng; Ju, Yongfeng; Zu, Xiaotao T.; Wang, Lumin M.; Zhang, Yanwen

    2010-05-01

    Room temperature Ti ion implantation and subsequent thermal annealing in N2 ambience have been used to fabricate the anatase and rutile structured N-doped TiO2 particles embedded in the surface region of fused silica. The Stopping and Range of Ions in Matter (SRIM) code simulation indicates a Gaussian distribution of implanted Ti, with a projected range of 74.4 nm and straggling of 16.5 nm. However, Rutherford backscattering spectrometry and transmission electron microscopy results show a much shallower distribution peaked at ~ 30 nm. Significant sputtering loss of silica substrates has occurred during implantation. Nanoparticles with size of 10-20 nm in diameter have formed after implantation. X-ray photoelectron spectroscopy indicates the coexistence of TiO2 and metallic Ti in the as-implanted samples. Metallic Ti is oxidized to anatase TiO2 after annealing at 600ºC, while rutile TiO2 forms by phase transformation after annealing at 900ºC. At the same time, N-Ti-O, Ti-O-N and/or Ti-N-O linkages have formed in the lattice of TiO2. A red shift of 0.34 eV in the absorption edge is obtained for N-doped anatase TiO2 after annealing at 600 ºC for 6 h. The absorbance increases in the ultraviolet and visible waveband.

  11. Processing and Characterization of SrTiO₃-TiO₂ Nanoparticle-Nanotube Heterostructures on Titanium for Biomedical Applications.

    PubMed

    Wang, Yu; Zhang, Dongmei; Wen, Cuie; Li, Yuncang

    2015-07-29

    Surface properties such as physicochemical characteristics and topographical parameters of biomaterials, essentially determining the interaction between the biological cells and the biomaterial, are important considerations in the design of implant materials. In this study, a layer of SrTiO3-TiO2 nanoparticle-nanotube heterostructures on titanium has been fabricated via anodization combined with a hydrothermal process. Titanium was anodized to create a layer of titania (TiO2) nanotubes (TNTs), which was then decorated with a layer of SrTiO3 nanoparticles via hydrothermal processing. SrTiO3-TiO2 heterostructures with high and low volume fraction of SrTiO3 nanoparticle (denoted by 6.3-Sr/TNTs and 1.4-Sr/TNTs) were achieved by using a hydrothermal processing time of 12 and 3 h, respectively. The in vitro biocompatibility of the SrTiO3-TiO2 heterostructures was assessed by using osteoblast cells (SaOS2). Our results indicated that the SrTiO3-TiO2 heterostructures with different volume fractions of SrTiO3 nanoparticles exhibited different Sr ion release in cell culture media and different surface energies. An appropriate volume fraction of SrTiO3 in the heterostructures stimulated the secretion of cell filopodia, leading to enhanced biocompatibility in terms of cell attachment, anchoring, and proliferation on the heterostructure surface. PMID:26136139

  12. Proton and neutron irradiation effect of Ti: Sapphires

    SciTech Connect

    Wang, G.; Zhang, J.; Yang, J.

    1999-07-01

    Various effects of proton and neutron irradiated Ti: sapphires were studied. Proton irradiation induced F, F{sup +} and V center in Ti: sapphires and 3310 cm{sup -1} infrared absorption, and made ultraviolet absorption edge shift to short wave. Neutron irradiation produced a number of F, F{sup +} and F{sub 2} centers and larger defects in Ti: sapphires, and changed Ti{sup 4+}into Ti{sup 3+} ions. Such valence state variation enhanced characteristic luminescence of Ti: sapphires, and no singular variances of intrinsic fluorescence spectra of Ti: sapphires took place with neutron flux of 1 x 10{sup 17}n/cm{sup 2}, but the fluorescence vanished with neutron flux of 1 x 10{sup 18}n/cm{sup 2} which means the threshold for the concentration of improving Ti{sup 3+} ions by neutron irradiation.

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

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Liang; Zeng, Yong

    2016-02-01

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

  14. Growth and characterization of TiO2 nanotubes from sputtered Ti film on Si substrate

    NASA Astrophysics Data System (ADS)

    Chappanda, Karumbaiah N.; Smith, York R.; Mohanty, Swomitra K.; Rieth, Loren W.; Tathireddy, Prashant; Misra, Mano

    2012-07-01

    In this paper, we present the synthesis of self-organized TiO2 nanotube arrays formed by anodization of thin Ti film deposited on Si wafers by direct current (D.C.) sputtering. Organic electrolyte was used to demonstrate the growth of stable nanotubes at room temperature with voltages varying from 10 to 60 V (D.C.). The tubes were about 1.4 times longer than the thickness of the sputtered Ti film, showing little undesired dissolution of the metal in the electrolyte during anodization. By varying the thickness of the deposited Ti film, the length of the nanotubes could be controlled precisely irrespective of longer anodization time and/or anodization voltage. Scanning electron microscopy, atomic force microscopy, diffuse-reflectance UV-vis spectroscopy, and X-ray diffraction were used to characterize the thin film nanotubes. The tubes exhibited good adhesion to the wafer and did not peel off after annealing in air at 350 °C to form anatase TiO2. With TiO2 nanotubes on planar/stable Si substrates, one can envision their integration with the current micro-fabrication technique large-scale fabrication of TiO2 nanotube-based devices.

  15. Modeling wear of cast Ti alloys

    PubMed Central

    Chan, Kwai S.; Koike, Marie; Okabe, Toru

    2007-01-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic–plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an α, α+β or β microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability. PMID:17224314

  16. Tensile deformation of NiTi wires.

    PubMed

    Gall, Ken; Tyber, Jeff; Brice, Valerie; Frick, Carl P; Maier, Hans J; Morgan, Neil

    2005-12-15

    We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong <111> fiber texture in the wire drawing direction, a grain size on the order of micrometers, and a high dislocation density. The more Ni rich wires contain fine second phase precipitates, while the wires with lower Ni content are relatively free of precipitates. The wire stress-strain response depends strongly on composition through operant deformation mechanisms, and cannot be explained based solely on measured differences in the transformation temperatures. We provide fundamental connections between the material structure, deformation mechanisms, and resulting stress-strain responses. The results help clarify some inconsistencies and common misconceptions in the literature. Ramifications on materials selection and design for emerging biomedical applications of NiTi shape memory alloys are discussed. PMID:16138359

  17. Effect of Sr/Ti Ratio on the Photocatalytic Properties of SrTiO3

    NASA Astrophysics Data System (ADS)

    Sulaeman, U.; Yin, S.; Sato, T.

    2011-10-01

    Since strontium titanate is a wide gap semiconductor, it requires UV light to generate the photocatalytic activities. Modification of strontium titanate to show photocatalytic activity under visible light irradiation is the essential work to efficiently utilize the sun light energy for environmental application. It is expected that the synthesis of SrTiO3 with variation of Sr/Ti atomic ratio could induce the defect crystals having unique photocatalytic properties. The SrTiO3 with various Sr/Ti atomic ratios were synthesized by microwave-assisted solvothermal reaction of SrCl2.6H2O and Ti(OC3H7)4 in KOH aqueous solutions with different atomic ratios of Sr/Ti. The products were characterized by TG-DTA, XRD and DRS. The photocatalytic activity was determined by DeNOx ability using LED lamps with the wavelengths of 627 nm (red), 530 nm (green), 445 nm (blue) and 390 nm (UV). The nanoparticles of perovskite type SrTiO3 with the particle size of 30-40 nm were successfully synthesized. The visible light responsive photocatalytic activity was generated by adding excess amount of Sr. The photocatalytic activity in visible light could be enhanced by an increase in the Sr/Ti atomic ratio up to 1.25, indicating that the visible light responsive photocatalytic activity is due to the generation of new band gap between the conduction band and valence band of SrTiO3 by the formation of oxygen vacancy.

  18. Ti(0) nanoparticles via lithium-naphthalenide-driven reduction.

    PubMed

    Schöttle, Christian; Doronkin, Dmitry E; Popescu, Radian; Gerthsen, Dagmar; Grunwaldt, Jan-Dierk; Feldmann, Claus

    2016-05-01

    Metallic titanium (Ti(0)) nanoparticles, 1.5 ± 0.4 nm in diameter, are obtained via lithium naphthalenide ([LiNaph])-driven reduction of TiCl4× 2THF in tetrahydrofuran (THF). HRTEM, fast Fourier transformation (FFT), optical spectra and X-ray absorption near edge structure (XANES) confirm their chemical composition. Besides their pyrophoric properties, their high reactivity is validated by direct transformation of Ti(0) into TiC maintaining the size. PMID:27086750

  19. Enhancement of NiTi superelastic endodontic instruments by TiO2 coating.

    PubMed

    Aun, Diego Pinheiro; Peixoto, Isabella Faria da Cunha; Houmard, Manuel; Buono, Vicente Tadeu Lopes

    2016-11-01

    Rotary nickel-titanium (NiTi) endodontic instruments were coated with a nanometric flexible TiO2 layer through dip-coating sol-gel. Control groups and coated samples of superelastic NiTi instruments model RaCe 25/0.06 (0.25mm tip-diameter, 6% conicity) were comparatively investigated with respect to the cutting efficiency, fatigue life, and corrosion resistance. Results showed an improvement in cutting efficiency for the coated samples and a high resistance to corrosion in NaClO. The coated instruments showed a better performance in fatigue life after corrosion. PMID:27524067

  20. Morphology, deformation, and defect structures of TiCr{sub 2} in Ti-Cr alloys

    SciTech Connect

    Chen, K.C.; Allen, S.M.; Livingston, J.D.

    1992-12-31

    The morphologies and defect structures of TiCr{sub 2} in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr{sub 2}. The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking fault, and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability.

  1. Prediction of Dynamic Response for Ti/TiB Functionally Graded Beams

    SciTech Connect

    Tuegel, Eric J.; Byrd, Larry W.; Beberniss, Timothy J.

    2008-02-15

    Functionally graded ceramic-metal materials are candidates for use in aerospace structures that are exposed to high temperatures. These structures will experience other demands such as significant pressure fluctuations that will cause panels to vibrate at high frequencies. These materials must be engineered for specific applications. Standard engineering methods were used to predict the response of Ti/TiB cantilever beams to quasi-static and dynamic loadings. Experiments were performed and compared to the predictions. The predictions and experiments did not agree due to significant uncertainty about the elastic modulus of TiB.

  2. Mechanical properties of NiTi-TiC shape-memory composites

    SciTech Connect

    Dunand, D.C.; Fukami-Ushiro, K.L.; Mari, D.; Roberts, J.A.; Bourke, M.A.

    1997-12-31

    This paper reviews recent work on the mechanical behavior of martensitic NiTi composites reinforced with 10--20 vol.% TiC particulates. The behavior of the composites is compared to that of unreinforced NiTi, so as to elucidate the effect of mismatch due to matrix transformation, thermal expansion, twinning or slip, in the presence of purely elastic particles. The twinning and subsequent thermal recovery of deformed composites, measured both macroscopically (by compressive testing and by dilatometry) and microscopically (by neutron diffraction), are summarized.

  3. Transformation of the {beta}-(Ti,V) phase in Ti-V-C alloys

    SciTech Connect

    Bursik, J.; Weatherly, G.C.

    1999-05-21

    The importance of Ti and V compounds with C and/or N, e.g. in precipitation strengthened steels, hard coatings, cutting tools, fuel cladding materials and in electronics, has stimulated extensive experimental work resulting in several isothermal sections of the Ti-V-C equilibrium phase diagram. The present paper reports on a study of the transformation of the {beta} phase in Ti-V-C alloys. The microstructure was studied by means of analytical TEM and HREM. Special attention was paid to the {beta} to {omega} transition and to a qualitative description of the influence of carbon on this process.

  4. Synthesis of Ti-based electrodes using Ti-salt flocculated sludge and their application in lithium-ion batteries

    SciTech Connect

    Kang, Jungwon; Rai, Alok Kumar; Kim, Sungjin; Choi, Eunseok; Yoo, Insun; Kim, Jongho; Kim, Jaekook

    2012-10-15

    We report a simple strategy to synthesize the nanostructured TiO{sub 2} samples by a solid state reaction using Ti-salt flocculated sludge. The structure and morphology of the Ti-salt flocculated sludge, nanostructured TiO{sub 2} samples and pure commercial Aldrich TiO{sub 2} powder were characterized by powder X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The electrochemical performances were evaluated in coin type cells. Nanostructured TiO{sub 2} samples, obtained by Ti-salt flocculated sludge shows a higher capacity and better cycling performances than pure commercial Aldrich TiO{sub 2} powder at the cutoff of 1.0–2.5 V especially at high current rate. The enhanced cycling performance can be attributed to the facts that their high crystallinity and uniform nano-sized distribution.

  5. Coherency effects on the mixing thermodynamics of cubic Ti1 -xAlxN /TiN (001) multilayers

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Abrikosov, Igor A.; Simak, Sergei I.; Odén, Magnus; Mücklich, Frank; Tasnádi, Ferenc

    2016-05-01

    In this work, we discuss the mixing thermodynamics of cubic (B1) Ti1 -xAlxN /TiN (001 ) multilayers. We show that interfacial effects suppress the mixing enthalpy compared to bulk Ti1 -xAlxN . The strongest stabilization occurs for compositions in which the mixing enthalpy of bulk Ti1 -xAlxN has its maximum. The effect is split into a strain and an interfacial (or chemical) contribution, and we show that both contributions are significant. An analysis of the local atomic structure reveals that the Ti atoms located in the interfacial layers relax significantly different from those in the other atomic layers of the multilayer. Considering the electronic structure of the studied system, we demonstrate that the lower Ti-site projected density of states at ɛF in the Ti1 -xAlxN /TiN multilayers compared to the corresponding monolithic bulk explains a decreased tendency toward decomposition.

  6. Photoinduced interaction between riboflavin and TiO 2 colloid

    NASA Astrophysics Data System (ADS)

    Kathiravan, A.; Renganathan, R.

    2008-12-01

    The adsorption of riboflavin on the surface of TiO 2 colloidal particles and the electron transfer process from its singlet excited state to the conduction band of TiO 2 were examined by absorption and fluorescence quenching measurements. The apparent association constants ( Kapp) were determined. The quenching mechanism is discussed involving electron transfer from riboflavin to TiO 2.

  7. Carrier-Controlled Ferromagnetism in SrTiO3

    DOE PAGESBeta

    Moetakef, Pouya; Williams, James R.; Ouellette, Daniel G.; Kajdos, Adam P.; Goldhaber-Gordon, David; Allen, S. James; Stemmer, Susanne

    2012-06-27

    Magnetotransport and superconducting properties are investigated for uniformly La-doped SrTiO3 films and GdTiO3/SrTiO3 heterostructures, respectively. GdTiO3/SrTiO3 interfaces exhibit a high-density 2D electron gas on the SrTiO3 side of the interface, while, for the SrTiO3 films, carriers are provided by the dopant atoms. Both types of samples exhibit ferromagnetism at low temperatures, as evidenced by a hysteresis in the magnetoresistance. For the uniformly doped SrTiO3 films, the Curie temperature is found to increase with doping and to coexist with superconductivity for carrier concentrations on the high-density side of the superconducting dome. The Curie temperature of the GdTiO3/SrTiO3 heterostructures scales with themore » thickness of the SrTiO3 quantum well. The results are used to construct a stability diagram for the ferromagnetic and superconducting phases of SrTiO3.« less

  8. Bringing Radiotracing to Titanium-Based Antineoplastics: Solid Phase Radiosynthesis, PET and ex Vivo Evaluation of Antitumor Agent [(45)Ti](salan)Ti(dipic).

    PubMed

    Severin, Gregory W; Nielsen, Carsten H; Jensen, Andreas I; Fonslet, Jesper; Kjær, Andreas; Zhuravlev, Fedor

    2015-09-24

    We present a novel solid-phase based (45)Ti radiolabeling methodology and the implementation of (45)Ti-PET in titanium-based antineoplastics using the showcase compound [(45)Ti](salan)Ti(dipic). This development is intended to allow elucidation of the biodistribution and pharmacokinetics of promising new Ti-based therapeutics. PMID:26312993

  9. Study on improved tribological properties by alloying copper to CP-Ti and Ti-6Al-4V alloy.

    PubMed

    Wang, Song; Ma, Zheng; Liao, Zhenhua; Song, Jian; Yang, Ke; Liu, Weiqiang

    2015-12-01

    Copper alloying to titanium and its alloys is believed to show an antibacterial performance. However, the tribological properties of Cu alloyed titanium alloys were seldom studied. Ti-5Cu and Ti-6Al-4V-5Cu alloys were fabricated in the present study in order to further study the friction and wear properties of titanium alloys with Cu additive. The microstructure, composition and hardness were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and hardness tester. The tribological behaviors were tested with ZrO2 counterface in 25% bovine serum using a ball-on-disc tribo-tester. The results revealed that precipitations of Ti2Cu intermetallic compounds appeared in both Ti-5Cu and Ti-6Al-4V-5Cu alloys. The tribological results showed an improvement in friction and wear resistance for both Ti-5Cu and Ti-6Al-4V-5Cu alloys due to the precipitation of Ti2Cu. The results also indicated that both CP-Ti and Ti-5Cu behaved better wear resistance than Ti-6Al-4V and Ti-6Al-4V-5Cu due to different wear mechanisms when articulated with hard zirconia. Both CP-Ti and Ti-5Cu revealed dominant adhesive wear with secondary abrasive wear mechanism while both Ti-6Al-4V and Ti-6Al-4V-5Cu showed severe abrasive wear and cracks with secondary adhesive wear mechanism due to different surface hardness integrated by their microstructures and material types. PMID:26354247

  10. Structural modification of TiAlN coatings by preliminary Ti Ion bombardment of a steel substrate

    NASA Astrophysics Data System (ADS)

    Shugurov, A. R.; Akulinkin, A. A.; Panin, A. V.; Perevalova, O. B.; Sergeev, V. P.

    2016-03-01

    The TiAlN coatings deposited onto steel 12Cr18Ni9Ti substrates before and after preliminary treatment by Ti ion beams are studied by X-ray diffraction, transmission electron microscopy, atomic force microscopy, and nanoindentation. The modification of the surface layer of a substrate is shown to change the structure and the preferred orientation of the coatings. The mechanical properties of the TiAlN coatings are found to depend substantially on the ion bombardment time.

  11. Design, Fabrication, and Testing of a TiN/Ti/TiN Trilayer KID Array for 3 mm CMB Observations

    NASA Astrophysics Data System (ADS)

    Lowitz, A. E.; Brown, A. D.; Mikula, V.; Stevenson, T. R.; Timbie, P. T.; Wollack, E. J.

    2016-03-01

    Kinetic inductance detectors (KIDs) are a promising technology for astronomical observations over a wide range of wavelengths in the mm and sub-mm regime. Simple fabrication, in as little as one lithographic layer, and passive frequency-domain multiplexing, with readout of up to ˜ 1000 pixels on a single line with a single cold amplifier, make KIDs an attractive solution for high-pixel-count detector arrays. We are developing an array that optimizes KIDs for optical frequencies near 100 GHz to expand their usefulness in mm-wave applications, with a particular focus on CMB B-mode measurement efforts in association with the QUBIC telescope. We have designed, fabricated, and tested a 20-pixel prototype array using a simple quasi-lumped microstrip design and pulsed DC reactive magnetron-sputtered TiN/Ti/TiN trilayer resonators, optimized for detecting 100 GHz (3 mm) signals. Here we present a discussion of design considerations for the array, as well as preliminary detector characterization measurements and results from a study of TiN trilayer properties.

  12. Design, Fabrication, and Testing of a TiN/Ti/TiN Trilayer KID Array for 3 mm CMB Observations

    NASA Astrophysics Data System (ADS)

    Lowitz, A. E.; Brown, A. D.; Mikula, V.; Stevenson, T. R.; Timbie, P. T.; Wollack, E. J.

    2016-08-01

    Kinetic inductance detectors (KIDs) are a promising technology for astronomical observations over a wide range of wavelengths in the mm and sub-mm regime. Simple fabrication, in as little as one lithographic layer, and passive frequency-domain multiplexing, with readout of up to ˜ 1000 pixels on a single line with a single cold amplifier, make KIDs an attractive solution for high-pixel-count detector arrays. We are developing an array that optimizes KIDs for optical frequencies near 100 GHz to expand their usefulness in mm-wave applications, with a particular focus on CMB B-mode measurement efforts in association with the QUBIC telescope. We have designed, fabricated, and tested a 20-pixel prototype array using a simple quasi-lumped microstrip design and pulsed DC reactive magnetron-sputtered TiN/Ti/TiN trilayer resonators, optimized for detecting 100 GHz (3 mm) signals. Here we present a discussion of design considerations for the array, as well as preliminary detector characterization measurements and results from a study of TiN trilayer properties.

  13. Fabrication of Ti substrate grain dependent C/TiO2 composites through carbothermal treatment of anodic TiO2.

    PubMed

    Rüdiger, Celine; Favaro, Marco; Valero-Vidal, Carlos; Calvillo, Laura; Bozzolo, Nathalie; Jacomet, Suzanne; Hejny, Clivia; Gregoratti, Luca; Amati, Matteo; Agnoli, Stefano; Granozzi, Gaetano; Kunze-Liebhäuser, Julia

    2016-04-01

    Composite materials of titania and graphitic carbon, and their optimized synthesis are highly interesting for application in sustainable energy conversion and storage. We report on planar C/TiO2 composite films that are prepared on a polycrystalline titanium substrate by carbothermal treatment of compact anodic TiO2 with acetylene. This thin film material allows for the study of functional properties of C/TiO2 as a function of chemical composition and structure. The chemical and structural properties of the composite on top of individual Ti substrate grains are examined by scanning photoelectron microscopy and micro-Raman spectroscopy. Through comparison of these data with electron backscatter diffraction, it is found that the amount of generated carbon and the grade of anodic film crystallinity correlate with the crystallographic orientation of the Ti substrate grains. On top of Ti grains with ∼(0001) orientations the anodic TiO2 exhibits the highest grade of crystallinity, and the composite contains the highest fraction of graphitic carbon compared to Ti grains with other orientations. This indirect effect of the Ti substrate grain orientation yields new insights into the activity of TiO2 towards the decomposition of carbon precursors. PMID:26975480

  14. Electronic properties of ultrathin GdTiO3 thin films and GdTiO3/SrTiO3 interfaces

    NASA Astrophysics Data System (ADS)

    Moetakef, Pouya; Jalan, Bharat; Zhang, Jack; Allen, S. James; Stemmer, Susanne

    2011-03-01

    Interfaces between Mott insulators, such as the rare earth titanates, and band insulators, such as SrTiO3, have recently attracted much attention. We report on the transport properties of epitaxial rare earth titanate thin films, GdTiO3, grown by molecular beam epitaxy (MBE) and those of heterostructures with SrTiO3 and GdTiO3. Growth of GdTiO3 was performed by shuttered growth of alternating titanium tetra isopropoxide (TTIP) and Gd fluxes, in the absence of any additional oxygen. We show that to stabilize the GdTiO3 perovskite phase, SrTiO3 buffer layers are needed for growth on perovskite substrates, such as LSAT ((LaAlO3)0.3(Sr2AlTaO6)0.7). The contribution of n-type SrTiO3 buffer layers and that of the SrTiO3/GdTiO3 interfaces to the transport properties are determined by measurements of the electrical resistance and Hall coefficient as a function of temperature and magnetic field.

  15. Controllable hydrothermal synthesis of rutile TiO2 hollow nanorod arrays on TiCl4 pretreated Ti foil for DSSC application

    NASA Astrophysics Data System (ADS)

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-11-01

    Rutile TiO2 nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl4 pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO2 nanorod arrays (H-TNRs). The TiCl4 pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl4 concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ~1.5 μm and diameter of ~200 nm, obtained on 0.15 M TiCl4 pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl4-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode.

  16. 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. PMID:24121827

  17. Formation and Thermodynamics of Mg-Al-Ti-O Complex Inclusions in Mg-Al-Ti-Deoxidized Steel

    NASA Astrophysics Data System (ADS)

    Ren, Ying; Zhang, Lifeng; Yang, Wen; Duan, Haojian

    2014-12-01

    The formation of Mg-Al-Ti-O complex inclusions in steel was investigated by laboratory experiments and thermodynamic calculation. The composition evolutions of Mg-Al-Ti-O inclusions in steel with different contents of [Al], [Mg], and [Ti] were discussed. Mg-Al-Ti-O complex inclusion with high TiOx content was liquid at 1873 K (1600 °C), indicating MgAl2O4 spinel inclusions can be modified to low melting temperature ones by combining TiOx component. The stability diagram of Al-Mg-Ti-O system inclusions in the molten steel at 1873 K (1600 °C) was calculated, considering many kinds of oxide inclusions such as MgO, Al2O3, TiOx, MgTi2O4, MgAl2O4, Al2TiO5, and liquid inclusion. The thermodynamic calculations are in good agreement with experimental results, which can predict the formation of Al-Mg-Ti-O complex inclusions in molten steel with a large concentration range of [Al], [Mg], and [Ti].

  18. Color tone and interfacial microstructure of white oxide layer on commercially pure Ti and Ti-Nb-Ta-Zr alloys

    NASA Astrophysics Data System (ADS)

    Miura-Fujiwara, Eri; Mizushima, Keisuke; Watanabe, Yoshimi; Kasuga, Toshihiro; Niinomi, Mitsuo

    2014-11-01

    In this study, the relationships among oxidation condition, color tone, and the cross-sectional microstructure of the oxide layer on commercially pure (CP) Ti and Ti-36Nb-2Ta-3Zr-0.3O were investigated. “White metals” are ideal metallic materials having a white color with sufficient strength and ductility like a metal. Such materials have long been sought for in dentistry. We have found that the specific biomedical Ti alloys, such as CP Ti, Ti-36Nb-2Ta-3Zr-0.3O, and Ti-29Nb-13Ta-4.6Zr, form a bright yellowish-white oxide layer after a particular oxidation heat treatment. The brightness L* and yellowness +b* of the oxide layer on CP Ti and Ti-36Nb-2Ta-3Zr-0.3O increased with heating time and temperature. Microstructural observations indicated that the oxide layer on Ti-29Nb-13Ta-4.6Zr and Ti-36Nb-2Ta-3Zr-0.3O was dense and firm, whereas a piecrust-like layer was formed on CP Ti. The results obtained in this study suggest that oxide layer coating on Ti-36Nb-2Ta-3Zr-0.3O is an excellent technique for dental applications.

  19. Electronic structure study of TiB{sub 2} and Ti{sub 2}B

    SciTech Connect

    Vashistha, M. Vyas, V.; Kabra, K.; Sharma, G.

    2015-06-24

    In this paper, the electronic properties of TiB{sub 2} and Ti{sub 2}B are computed within the framework of Density Functional Theory (DFT) based on Linear Combination of Atomic Orbitals (LCAO) method. In the present calculations, the generalized gradient approximation (GGA) proposed by Perdew-Burke-Erenzerhof (PBE) and Becke’s scheme are considered to treat the correlation and exchange effects respectively. TiB{sub 2} crystallizes in the hexagonal AlB{sub 2} type structure which is designated as C32 with the space group P6/mmm. While the crystal structure of Ti{sub 2}B described in this paper is isomorphous to the body centered tetragonal (Al{sub 2}Cu - type) structure with space group I4/mcm.

  20. Electronic structure study of TiB2 and Ti2B

    NASA Astrophysics Data System (ADS)

    Vashistha, M.; Kabra, K.; Vyas, V.; Sharma, G.

    2015-06-01

    In this paper, the electronic properties of TiB2 and Ti2B are computed within the framework of Density Functional Theory (DFT) based on Linear Combination of Atomic Orbitals (LCAO) method. In the present calculations, the generalized gradient approximation (GGA) proposed by Perdew-Burke-Erenzerhof (PBE) and Becke's scheme are considered to treat the correlation and exchange effects respectively. TiB2 crystallizes in the hexagonal AlB2 type structure which is designated as C32 with the space group P6/mmm. While the crystal structure of Ti2B described in this paper is isomorphous to the body centered tetragonal (Al2Cu - type) structure with space group I4/mcm.

  1. Giant persistent photoconductivity in BaTiO3/TiO2 heterostructures

    NASA Astrophysics Data System (ADS)

    Plodinec, Milivoj; Šantić, Ana; Zavašnik, Janez; Čeh, Miran; Gajović, Andreja

    2014-10-01

    The persistent photoconductivity (PPC) effect in nanotube arrays of barium titanate and TiO2 (BTO/TiO2NT) was studied at room temperature under daylight illumination. The BTO/TiO2NT heterostructures exhibited a giant PPC effect that was six orders of magnitude higher than the dark conductivity, followed by a slow relaxation for 3 h. The PPC in this material was explained by the existence of defects at the surfaces and the interfaces of the investigated heterostructures. The sample was prepared using a two-step synthesis: the anodization of a Ti-foil and a subsequent hydrothermal synthesis. The structural and electrical characteristics were studied by micro-Raman spectroscopy, field-emission-gun scanning electron microscopy, and impedance spectroscopy.

  2. Giant persistent photoconductivity in BaTiO{sub 3}/TiO{sub 2} heterostructures

    SciTech Connect

    Plodinec, Milivoj; Šantić, Ana; Gajović, Andreja; Zavašnik, Janez; Čeh, Miran

    2014-10-13

    The persistent photoconductivity (PPC) effect in nanotube arrays of barium titanate and TiO{sub 2} (BTO/TiO{sub 2}NT) was studied at room temperature under daylight illumination. The BTO/TiO{sub 2}NT heterostructures exhibited a giant PPC effect that was six orders of magnitude higher than the dark conductivity, followed by a slow relaxation for 3 h. The PPC in this material was explained by the existence of defects at the surfaces and the interfaces of the investigated heterostructures. The sample was prepared using a two-step synthesis: the anodization of a Ti-foil and a subsequent hydrothermal synthesis. The structural and electrical characteristics were studied by micro-Raman spectroscopy, field-emission-gun scanning electron microscopy, and impedance spectroscopy.

  3. TiC growth in C fiber/Ti alloy composites during liquid infiltration

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    A cylindrical model is developed for predicting the reaction zone thickness of carbon fiber-reinforced Ti-matrix composites, and good agreement is obtained between its predicted values and experimental results. The reaction-rate constant for TiC formation is estimated to be 1.5 x 10 exp -9 sq cm/sec. The model is extended to evaluate the relationship between C-coating thicknesses on SiC fibers and processing times.

  4. High-Quality TiS2 For Li/TiS2 Cells

    NASA Technical Reports Server (NTRS)

    Huang, Chen-Kuo; Surampudi, Subbarao; Shen, David H.; Delgiannis, Fotios; Halpert, Gerald

    1992-01-01

    Modified process for synthesis of battery-grade titanium sulfide (TiS2) yields substantially improved material for Li/TiS2 electrochemical cells. Includes all-vapor-phase reaction between sulfur and titanium. Product less dense and more homogeneous, consists of smaller particles of higher crystalline quality, and purer. Cells have high cathode utilization and long cycle life performance. Expected to find applications in rechargeable lithium batteries for spacecraft, military equipment, telecommunication systems, automobiles, and consumer products.

  5. Crystalline Al1 - x Ti x phases in the hydrogen cycled NaAlH4 + 0.02TiCl3 system

    NASA Astrophysics Data System (ADS)

    Pitt, M. P.; Vullum, P. E.; Sørby, M. H.; Emerich, H.; Paskevicius, M.; Buckley, C. E.; Gray, E. MacA.; Walmsley, J. C.; Holmestad, R.; Hauback, B. C.

    2013-03-01

    The hydrogen (H) cycled planetary milled (PM) NaAlH4 + 0.02TiCl3 system has been studied by high resolution synchrotron X-ray diffraction and transmission electron microscopy during the first 10 H cycles. After the first H absorption, we observe the formation of four nanoscopic crystalline (c-) Ti-containing phases embedded on the NaAlH4 surface, i.e. Al2Ti, Al3Ti, Al82Ti18 and Al89Ti11, with 100% of the originally added Ti atoms accounted for. Al2Ti and Al3Ti are observed morphologically as a mechanical couple on the NaAlH4 surface, with a moderately strained interface. Electron diffraction shows that the Al82Ti18 phase retains some ordering from the L12 structure type, with the observation of forbidden (100) ordering reflections in the fcc Al82Ti18 lattice. After 2 H cycles the NaAlH4 + 0.02TiCl3 system displays only two crystalline Ti-containing phases, Al3Ti and Al89Ti11. After 10 H cycles, the Al89Ti11 is completely converted to Al85Ti15. Al89Ti11, Al85Ti15 and Al3Ti do not display any ordering reflections, and they are modeled in the A1 structure type. Quantitative phase analysis indicates that the Al3Ti proportion continues to increase with further H cycles. The formation of Ti-poor Al1 - x Ti x (x < 0.25) phases in later H cycles is detrimental to hydrogenation kinetics, compared to the starting Ti-richer near-surface Al2Ti/NaAlH4 interface present during the first absorption of hydrogen.

  6. Introducing the TI-Nspire CAS Learning Technology

    NASA Astrophysics Data System (ADS)

    Osbourne, Michael

    2008-03-01

    Engage your students! In this hands-on workshop, we will demonstrate how TI's newest graphing technology can be integrated into the physics classroom. Come experience both the TI-NspireT CAS Handheld and the TI- NspireT CAS Computer Software. The new TI-Nspire learning technology has been developed to allow students to explore physics and to better understand concepts through the manipulation of complex formulas,graphing, spreadsheets, data analysis, and simulations. During the workshop you will receive an overview of the technology, sample activities, along with the opportunity to experience how TI-Nspire CAS can be effectively integrated into the physics classroom. Limited to 20 participants.

  7. TEM studies of the nitrided Ni-Ti surface layer.

    PubMed

    Lelatko, J; Paczkowski, P; Wierzchoń, T; Morawiec, H

    2006-09-01

    The structure of surface layer, obtained on the nearly equiatomic Ni-Ti alloy after nitriding under glow discharge conditions at temperatures 700 or 800 degrees C, was investigated. The structural characterization of the intruded layer was performed on cross-sectional thin foils by the use of the transmission and scanning electron microscopes. The obtained results show that the nitrided layers consist mainly of the nanocrystalline TiN phase and small amount of Ti(2)N. Between the nitrided layers and beta-NiTi matrix an intermediate Ti(2)Ni phase layer was observed. PMID:17059538

  8. Atomistic modeling of ternary additions to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt and Ni-Ti-Hf shape memory alloys

    NASA Astrophysics Data System (ADS)

    Mosca, H. O.; Bozzolo, G.; del Grosso, M. F.

    2012-08-01

    The behavior of ternary and quaternary additions to NiTi shape memory alloys is investigated using a quantum approximate method for the energetics. Ternary additions X to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt, and Ni-Ti-Hf alloys, for X=Au, Pt, Ir, Os, Re, W, Ta,Ag, Pd, Rh, Ru, Tc, Mo, Nb, Zr, Zn, Cu, Co, Fe, Mn, V, Sc, Si, Al and Mg are considered. Bulk properties such as lattice parameter, energy of formation, and bulk modulus of the B2 alloys are studied for variations due to the presence of one or two simultaneous additives.

  9. Diffusion Research in BCC Ti-Al-Mo Ternary Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Yi; Tang, Bin; Xu, Guanglong; Wang, Chuanyun; Kou, Hongchao; Li, Jinshan; Cui, Yuwen

    2014-04-01

    Interdiffusion in Ti-Al-Mo β solid solution was investigated at 1523 K (1250 °C) by analyzing diffusion couples. From the concentration profiles analytically represented by error function expansion (ERFEX), the ternary interdiffusion coefficients and impurity diffusivity were extracted by the Whittle-Green and generalized Hall methods. A comparison of the diffusion in five Ti-Al-X (Co, Cr, Fe, Mo, and V) ternaries reveals Ti-Al-Mo is comparably like Ti-Al-(Cr, V) while Ti-Al-(Co, Fe) are predominantly of interstitial nature.

  10. Influence of composition and bottom electrode properties on the local conductivity of TiN/HfTiO2 and TiN/Ru/HfTiO2 stacks

    NASA Astrophysics Data System (ADS)

    Martin, Dominik; Grube, Matthias; Reinig, Peter; Oberbeck, Lars; Heitmann, Johannes; Weber, Walter M.; Mikolajick, Thomas; Riechert, Henning

    2011-01-01

    HfTiO2 layers of various stoichiometries where deposited by physical vapor depostion on TiN and TiN/Ru bottom electrodes (BE) in order to determine the influence of composition, conduction band offset, and BE morphology on the overall leakage current characteristics. Current-voltage spectroscopy, transmission electron microscopy, electron energy loss spectroscopy, and conductive atomic force microscopy studies show increased leakage current and charge trapping with increased Ti content. The interplay of conduction band offset and trap density were studied. The influence of Ru bottom electrode roughness on the leakage current is higher than the influence of Ti content and low conduction band offset.

  11. Adhesion and corrosion behavior of Al-Zn and TiN/Ti/TiN coatings on a Du-0.75 wt% ti alloy. (Reannouncement with new availability information)

    SciTech Connect

    Chang, F.C.; Levy, M.; Huie, R.; Kane, M.; Buckley, P.

    1992-08-01

    Al-Zn alloy and multilayer TiN/Ti/TiN thin coatings were deposited on DU-0; 75Ti alloy specimens by a cathodic arc plasma physical vapor deposition process. The quality, soundness and adhesion of the coatings to the substrate were evaluated by automatic scratch testing, in combination with optical and scanning electron microscopy examination of the scratch morphology. The galvanic corrosion behavior of DU-0.75Ti alloy coupled to the coated alloys and aluminum alloy 7075-T6 was also investigated by electrochemical tests in a 0.5 N NaCl aqueous solution.

  12. Fatigue Behavior of TiN and TiCN Coated a Rotor Turbine Steel

    NASA Astrophysics Data System (ADS)

    Suh, Chang Min; Kim, Kyung Ryul; Kang, Yong Goo; Suh, Duck Young; Kim, Chang Keun

    In order to clarify the effect of ceramic coating films on the fatigue strength, and crack initiation of material, fatigue tests were carried out in room air, using the round plain specimens and compact tension specimens of 1Cr-1Mo-0.25V steel coated with TiN and TiCN are ion plating (AIP) process. It was observed that the scatter band of fatigue life at low fatigue strengths was wider than that at high fatigue strengths. The obvious improvement of fatigue life was confirmed in TiCN coated specimens for the region of low fatigue strengths, as compared with uncoated and TiN coated specimens. It was explained that the increase of fatigue life in the TiCN coated material was attributed to the retardation of crack initiation due to the restriction of surface plastic deformation in the substrate with hard coating layer. Also, the fatigue strength at 107 cycles of ceramic coated material was increased about 15 ~ 21% higher than that of base material. The fatigue crack of TiCN coated material was mainly initiated at the inclusions of Al compositions near the substrate under coating film.

  13. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

    PubMed Central

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-01-01

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19′ martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19′ martensitic transformation, and (V) plastic deformation of the specimen. PMID:27049025

  14. Effect of Ti concentration on the structure and texture of SiTiOC glasses

    SciTech Connect

    Tellez, L.; Rubio, J.; Valenzuela, M.A.; Rubio, F.; Oteo, J.L.

    2009-06-15

    Five different silicon-titanium organic-inorganic hybrid materials were prepared by the reaction of tetraethoxysilane, titanium tetrabutoxide and silanol-terminated polydimethylsiloxane. Si-Ti oxycarbide glasses were prepared by pyrolysis of the hybrid materials in nitrogen atmosphere in the range of 400 to 1500 deg. C. The obtained Si-Ti oxycarbide materials were characterized by Fourier Transform-Infra Red spectroscopy, X-ray-diffraction, mercury porosimetry and SEM. The study indicated that the reactivity towards water increases up to 1000 deg. C, at higher temperatures it decreases for all samples. During the pyrolysis, Ti atoms were incorporated into the silicate network leading to the formation of Si-Ti oxycarbide glasses, except with sample containing 7% of Ti which presented also the formation of {beta}-SiC and TiC crystalline phases. The porosity was increased up to 600 deg. C and then decreased tending to disappear at 1500 deg. C. When the titanium concentration increased from 1 to 3% in the oxycarbide glass, the porosity decreased; for higher concentration, an increase in the porosity was observed.

  15. Micro-Arc oxidation of Ti in a solution of sulfuric acid and Ti +3 salt

    NASA Astrophysics Data System (ADS)

    Ragalevičius, Rimas; Stalnionis, Giedrius; Niaura, Gediminas; Jagminas, Arūnas

    2008-01-01

    A comparative study was performed on the behavior of titanium electrode in a sulfuric acid solution with and without Ti +3 during micro-arc oxidation under the constant current density control regime. The composition and microstructure of the obtained micro-arc films were analyzed using scanning electron microscopy, glancing-angle X-ray diffractometry, Raman and energy-dispersive X-ray spectroscopies. We have shown that addition of a Ti +3 salt extends the region of current densities ( ja) can be used for micro-arc oxidation of Ti and results in an obvious change of sparking behavior from extensive, large and long-played sparks to numerous, small and short sparks. As a consequence, the titania films formed in the Ti +3-containing solutions are relatively thick, more uniform, composed of almost pure crystalline anatase and rutile phases of TiO 2, and contain a network of evenly distributed small pores. It has also been shown that these films are promising for applications in catalysis, sensors and optoelectronics. The Raman spectra indicate that an increase in the electrolysis time of titanium in the Ti +3-containing solution leads to the increase in rutile content, as expected.

  16. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    NASA Astrophysics Data System (ADS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-03-01

    The fabrication method and characterization results of a TiO2-TiO2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO2 crystallites embedded in a matrix of nanometric TiO2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant.

  17. Redistribution of Ti and Al in deuterium charged TiAl

    NASA Technical Reports Server (NTRS)

    Legzdina, D.; Robertson, I. M.; Birnbaum, H. K.

    1992-01-01

    The redistribution of titanium and aluminum in a single-phase TiAl alloy that has been exposed to a high pressure of deuterium gas at high temperature is studied. The microstructure in the as-received, uncharged condition consisted of single-phase gamma TiAl grains and a random distribution of precipitates. Precipitates were distributed throughout the matrix and along the grain boundaries. The chemistry of the precipitates varied considerably; some were rich in Al, while other were mostly Ti with some Si and Al. The dislocation density in most grains was low, although in a few grains a high dislocation density was observed. FCC deuterides with a lattice parameter of 0.45 nm form in a Ti-52.1Al-2.1Ta (at. pct) alloy after exposure to 1.38 MPa of deuterium gas at 650 C for 213 hr. The structure and lattice parameter are consistent with the formation of Ti(l)D2. The deuterides that form in this alloy are enriched in Ti and deficient in Al and Ta compared to the deuteride-free matrix. Regions of the matrix contiguous with the deuterides have a correspondingly enhanced aluminum and tantalum concentration.

  18. Photoluminescence characteristics of ZnS nanocrystallites doped with Ti3+and Ti4+

    NASA Astrophysics Data System (ADS)

    Yang, P.; Lü, M.; Xu, D.; Yuan, D.; Song, C.; Zhou, G.

    Direct synthesis of ZnS nanocrystallites doped with Ti3+ or Ti4+ by precipitation has led to novel photoluminescence properties. Detailed X-ray diffraction (XRD), fluorescence spectrophotometry, UV-vis spectrophotometry and X-ray photoelectron spectroscopy (XPS) analysis reveal the crystal lattice structure, average size, emission spectra, absorption spectra and composition. The average crystallite size doped with different mole ratios, estimated from the Debye-Scherrer formula, is about 2.6+/-0.2 nm. The nanoparticles can be doped with Ti3+ and Ti4+ during the synthesis without the X-ray diffraction pattern being altered. The strong and stable visible-light emission has been observed from ZnS nanocrystallites doped with Ti3+ (its maximum fluorescence intensity is about twice that of undoped ZnS nanoparticles). However, the fluorescence intensity of the ZnS nanocrystallites doped with Ti4+ is almost the same as that of the undoped ZnS nanoparticles. The emission peak of the undoped sample is at 440-450 nm. The emission spectrum of the doped sample consists of two emission peaks, one at 420-430 nm and the other at 510 nm.

  19. Redistribution of Ti and Al in deuterium charged TiAl

    SciTech Connect

    Legzdina, D.; Robertson, I.M.; Birnbaum, H.K. )

    1992-06-01

    The redistribution of titanium and aluminum in a single-phase TiAl alloy that has been exposed to a high pressure of deuterium gas at high temperature is studied. The microstructure in the as-received, uncharged condition consisted of single-phase gamma TiAl grains and a random distribution of precipitates. Precipitates were distributed throughout the matrix and along the grain boundaries. The chemistry of the precipitates varied considerably; some were rich in Al, while other were mostly Ti with some Si and Al. The dislocation density in most grains was low, although in a few grains a high dislocation density was observed. FCC deuterides with a lattice parameter of 0.45 nm form in a Ti-52.1Al-2.1Ta (at. pct) alloy after exposure to 1.38 MPa of deuterium gas at 650 C for 213 hr. The structure and lattice parameter are consistent with the formation of Ti(l)D2. The deuterides that form in this alloy are enriched in Ti and deficient in Al and Ta compared to the deuteride-free matrix. Regions of the matrix contiguous with the deuterides have a correspondingly enhanced aluminum and tantalum concentration. 10 refs.

  20. Multilayer (TiN, TiAlN) ceramic coatings for nuclear fuel cladding

    NASA Astrophysics Data System (ADS)

    Alat, Ece; Motta, Arthur T.; Comstock, Robert J.; Partezana, Jonna M.; Wolfe, Douglas E.

    2016-09-01

    In an attempt to develop an accident-tolerant fuel (ATF) that can delay the deleterious consequences of loss-of-coolant-accidents (LOCA), multilayer coatings were deposited onto ZIRLO® coupon substrates by cathodic arc physical vapor deposition (CA-PVD). Coatings were composed of alternating TiN (top) and Ti1-xAlxN (2-layer, 4-layer, 8-layer and 16-layer) layers. The minimum TiN top coating thickness and coating architecture were optimized for good corrosion and oxidation resistance. Corrosion tests were performed in static pure water at 360 °C and 18.7 MPa for up to 90 days. The optimized coatings showed no spallation/delamination and had a maximum of 6 mg/dm2 weight gain, which is 6 times smaller than that of a control sample of uncoated ZIRLO® which showed a weight gain of 40.2 mg/dm2. The optimized architecture features a ∼1 μm TiN top layer to prevent boehmite phase formation during corrosion and a TiN/TiAlN 8-layer architecture which provides the best corrosion performance.

  1. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires.

    PubMed

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-01-01

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19' martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19' martensitic transformation, and (V) plastic deformation of the specimen. PMID:27049025

  2. Thermopower of the 312 MAX phases Ti3SiC2 , Ti3GeC2 , and Ti3AlC2

    NASA Astrophysics Data System (ADS)

    Chaput, L.; Hug, G.; Pécheur, P.; Scherrer, H.

    2007-01-01

    The electronic structure and the thermoelectric tensor are calculated for the 312 MAX phases Ti3SiC2 , Ti3GeC2 , and Ti3AlC2 . The thermoelectric tensor is shown to be anisotropic in all cases. However, for Ti3SiC2 and Ti3GeC2 we find the components of the thermoelectric tensor to be negative along the z direction, Sz<0 , and positive in the basal plane, Sx>0 , whereas Sz>0 and Sx>0 over a large temperature range for Ti3AlC2 . This accounts for the different behavior experimentally observed. Moreover, the calculated thermopower as a function of temperature is in good agreement with experiments on polycrystals.

  3. Photoreduction of CO2 on TiO2/SrTiO3 Heterojunction Network Film

    NASA Astrophysics Data System (ADS)

    Bi, Yongsheng; Zong, Lanlan; Li, Chen; Li, Qiuye; Yang, Jianjun

    2015-08-01

    Nanotube titanic acid (NTA) network film has a porous structure and large BET surface area, which lead them to possessing high utilization of the incident light and strong adsorption ability. We used NTA as the precursor to fabricate a TiO2/ SrTiO3 heterojunction film by the hydrothermal method. In the process of the reaction, part of NTA reacted with SrCl2 to form SrTiO3 nanocubes, and the remainder dehydrated to transform to the rutile TiO2. The ratio of TiO2 and SrTiO3 varied with the hydrothermal reaction time. SEM and TEM images indicated that SrTiO3 nanocubes dispersed uniformly on TiO2 film, and the particle size and crystallinity of SrTiO3 nanocubes increased with the reaction time prolonging. The TiO2/SrTiO3 heterojunction obtained by 1 h showed the best activity for CO2 photoreduction, where the mole ratio of TiO2 and SrTiO3 was 4:1. And the photo-conversion efficiency of CO2 to CH4 improved remarkably after the foreign electron traps of Pt and Pd nanoparticles were loaded. The highest photocatalytic production rate of CH4 reached 20.83 ppm/h cm2. In addition, the selectivity of photoreduction product of CO2 was also increased apparently when Pd acted as the cocatalyst on TiO2/SrTiO3 heterojunction film.

  4. Investigation of the Contact Resistance between Ti/TiN and Ru in Metal-1/Plate Contacts of Ruthenium Insulator Silicon Capacitor

    NASA Astrophysics Data System (ADS)

    Yun, Ju Young; Kim, Byung Hee; Seo, Jung Hun; Lee, Jong Myeong; Kang, Sang Bom; Choi, Gil Heyun; Chung, U In; Moon, Joo Tae

    2003-04-01

    The contact resistance between Ti/TiN and a Ru electrode in metal-1/plate contacts of ruthenium insulator silicon (RIS) capacitor is investigated. When physical vapor deposition (PVD) Ti/TiN was used as a barrier metal for the metal contact process, a high contact resistance of more than 5000 Ω/contact was obtained due to the oxidation of Ti by the residual oxygen in Ru electrode. On the other hand, with a plasma enhanced chemical vapor deposition (PECVD) Ti/CVD TiN barrier metal, oxidation of Ti was not observed and subsequently a low contact resistance of 15 Ω/contact was obtained. The absence of Ti oxidation with PECVD Ti/CVD TiN can be explained by the reduction of oxygen in the Ru electrode due to the H2 plasma environment in the PECVD-Ti process.

  5. Corrosion resistance tests on NiTi shape memory alloy.

    PubMed

    Rondelli, G

    1996-10-01

    The corrosion performances of NiTi shape memory alloys (SMA) in human body simulating fluids were evaluated in comparison with other implant materials. As for the passivity current in potentiostatic conditions, taken as an index of ion release, the values are about three times higher for NiTi than for Ti6Al4V and austenitic stainless steels. Regarding the localized corrosion, while plain potentiodynamic scans indicated for NiTi alloy good resistance to pitting attack similar to Ti6Al4V, tests in which the passive film is abruptly damaged (i.e. potentiostatic scratch test and modified ASTM F746) pointed out that the characteristics of the passive film formed on NiTi alloy (whose strength can be related to the alloy's biocompatibility) are not as good as those on Ti6Al4V but are comparable or inferior to those on austenitic stainless steels. PMID:8894095

  6. Biocompatibility of nanotube formed Ti-30Nb-7Ta alloys.

    PubMed

    Kim, Eun-Sil; Choe, Han-Cheol

    2014-11-01

    The purpose of this study was to investigate the biocompatibility of Ti-30Nb-7Ta alloy surface decorated with TiO2 nanotubes by anodization in an electrolyte containing 1 M H3PO4 and 0.8 wt.% NaF with an applied voltage of 10 V for 2 h. The anodization was carried out using a scanning potentiostat. The microstructures of alloys and morphology of the nanotubes were investigated by optical microscopy, field emission scanning electron microscopy, and X-ray diffractometry. In comparison to the Ti-30Nb-3Ta alloy, the Ti-30Nb-7Ta alloy contained a lower amount of α" phase, while the β phase was higher. In this study, we observed the formation of a spongy porous layer on the Ti-30Nb-7Ta alloy, while the Ti-30Nb and Ti-30Nb-3Ta alloys showed an absence of such a spongy layer. PMID:25958540

  7. Control of interface reactions in SIC/TI composites

    NASA Technical Reports Server (NTRS)

    Houska, C. R.; Rao, V.

    1982-01-01

    The reaction between a 0.5 to 1.0 Al film and a thick Ti substrate to form TiAl3 occurs very rapidly on heating to 635 C and causes the Al to be confined to the surface region. After heating to 900 C Ti3Al is formed with little release of Al into alpha Ti. Further annealing at 900 C eventually causes the Ti3Al phase to decompose and a substantial amount of Al is released into alpha Ti. The interdiffusion coefficient for Al in alpha Ti at 900 C increases by less than one order of magnitude as Al is varied from 0 to 20 at %. These data were obtained from the (101) X-ray diffraction intensity band using polycrystalline samples. Improvements in the analysis of X-ray diffraction data for the determination of composition profiles are discussed.

  8. The corrosivity and passivity of sputtered Mg-Ti alloys

    SciTech Connect

    Song, Guang -Ling; Unocic, Kinga A.; Meyer, III, Harry M.; Cakmak, Ercan; Brady, Michael P.; Gannon, Paul E.; Himmer, Phil; Andrews, Quinn

    2015-11-30

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

  9. The corrosivity and passivity of sputtered Mg-Ti alloys

    DOE PAGESBeta

    Song, Guang -Ling; Unocic, Kinga A.; Meyer, III, Harry M.; Cakmak, Ercan; Brady, Michael P.; Gannon, Paul E.; Himmer, Phil; Andrews, Quinn

    2015-11-30

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

  10. Local structure of deuterated Ti-Zr alloy

    NASA Astrophysics Data System (ADS)

    Fukunaga, T.; Itoh, K.; Hashi, K.; Aoki, K.

    The Ti-Zr alloy system is isomorphous over the total concentration range. A neutron zero-scattering alloy can be obtained at the composition Ti0.676Zr0.324 because of negative and positive coherent neutron scattering amplitudes of Ti and Zr respectively. A (Ti0.676Zr0.324)D0.31 amorphous alloy was synthesized by mechanical alloying (MA) under a deuterium-gas atmosphere of 0.08 MPa. In contrast, it is found that the MA of Ti and Zr powders under a deuterium-gas atmosphere of 2.0 MPa forms a nano-crystalline (Ti0.676Zr0.324)D1.54 alloy, which is composed of TiH2 and ZrH2 crystalline compounds.

  11. Microstructural and mechanical characteristics of W-2Ti and W-1TiC processed by hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Muñoz, A.; Savoini, B.; Tejado, E.; Monge, M. A.; Pastor, J. Y.; Pareja, R.

    2014-12-01

    W-2Ti and W-1TiC alloys were produced by mechanical alloying and consolidation by hot isostatic pressing. The composition and microstructural characteristics of these alloys were studied by X-ray diffraction, energy dispersion spectroscopy and scanning electron microscopy. The mechanical behavior of the consolidated alloys was characterized by microhardness measurements and three point bending tests. The mechanical characteristics of the W-2Ti alloy appear to be related to solution hardening. In W-1TiC, the residual porosity should be responsible for the poor behavior observed in comparison with W-2Ti.

  12. TiCl4 as a source of TiO2 particles for laser anemometry measurements in hot gas

    NASA Technical Reports Server (NTRS)

    Weikle, Donald H.; Seasholtz, Richard G.; Oberle, Lawrence G.

    1990-01-01

    A method of reacting TiCl4 with water saturated gaseous nitrogen (GN2) at the entrance into a high temperature gas flow is described. The TiO2 particles formed are then entrained in the gas flow and used as seed particles for making laser anemometry (LA) measurements of the flow velocity distribution in the hot gas. Scanning electron microscope photographs of the TiO2 particles are shown. Data rate of the LA processor was measured to determine the amount of TiO2 formed. The TiCl4 and mixing gas flow diagram is shown. This work was performed in an open jet burner.

  13. Procurement of V-Cr-Ti alloys to study minor variations on V-4Cr-4Ti

    SciTech Connect

    Grossbeck, M.L.

    1998-03-01

    The alloys V-6Cr-3Ti, V-4Cr-4Ti-Si, V-6Cr-6Ti, and V-3Cr-3Ti, were prepared by Teledyne Wah Chang Albany Corp. in 1994. Plate and sheet ranging from 0.76 mm to 6.25 mm with residual material being left in 12--20 mm thick bar were fabricated. Although the heats were prepared on a pilot plant scale using different equipment, an effort was made to keep the processing as close to Wah Chang Heat 832665, the reference fusion heat of V-4Cr-4Ti, as possible.

  14. Effect of Ti pretreatment on photoelectric properties of TiO2 layers prepared by plasma-anodic oxidation

    NASA Astrophysics Data System (ADS)

    Mikula, Milan; Blecha, Jozef; Čeppan, Michal; Panák, Ján

    1995-12-01

    Photoactive TiO2 layers were formed by anodic oxidation of Ti in O2 RF plasma under various conditions and Ti surface pretreatment. The photocurrent spectrum in 1M NaOH was used to calculate the quantum efficiency of the photocurrent production and the band-gap energy for indirect transitions. Photoelectrochemical properties of TiO2 layers were studied on the decomposition of p-cresol water solution. The method of Ti surface pretreatment (mechanical polishing or chemical etching) has a decisive influence on the photoelectrochemical properties and the structure of the polycrystalline oxide, rutile, anatase or amorphous phase content.

  15. Charge Transport at Ti-Doped Hematite (001)/Aqueous Interfaces

    SciTech Connect

    Chatman, Shawn ME; Pearce, Carolyn I.; Rosso, Kevin M.

    2015-03-10

    Solid-state transport and electrochemical properties of Ti-doped hematite (001) epitaxial thin films (6.0, 8.3, and 16.6 at% Ti) were probed to achieve a better understanding of doped hematite for photoelectrochemical (PEC) applications. Room temperature resistivity measurements predict a resistivity minimum near 10 at% Ti doping, which can be rationalized as maximizing charge compensating Fe2+ concentration and Fe3+ electron accepting percolation pathways simultaneously. Temperature dependent resistivity data are consistent with small polaron hopping, revealing an activation energy that is Ti concentration dependent and commensurate with previously reported values (≈ 0.11 eV). In contact with inert electrolyte, linear Mott-Schottky data at various pH values indicate that there is predominantly a single donor for Ti-doped hematite at 6.0 at% Ti and 16.6 at% Ti concentrations. Two slope Mott-Schottky data at pH extremes indicate the presence of a second donor or surface state in the 8.3 at% Ti-doped film, with an energy level ≈ 0.7 eV below the Fermi level. Mott-Schottky plots indicate pH and Ti concentration dependent flatband potentials of -0.4 to -1.1 V vs. Ag/AgCl, commensurate with previously reported data. Flatband potentials exhibited super-Nernstian pH dependence ranging from -69.1 to -101.0 mV/pH. Carrier concentration data indicate that the Fermi energy of the Ti-doped system is Ti concentration dependent, with a minimum of 0.15 eV near 10 at% Ti. These energy level data allow us to construct an energy band diagram for Ti-doped hematite electrode/electrolyte interfaces, and to determine a Ti-doping concentration t

  16. Cytocompatibility and early osseointegration of nanoTiO2-modified Ti-24 Nb-4 Zr-7.9 Sn surfaces.

    PubMed

    Liu, X H; Wu, L; Ai, H J; Han, Y; Hu, Y

    2015-03-01

    This study aimed to evaluate the cytocompatibility and early osseointegration of Ti-24 Nb-4 Zr-7.9 Sn (Ti-2448) surfaces that were modified with a nanoscale TiO2 coating. The coating was fabricated using a hydrothermal synthesis method to generate nanoTiO2/Ti-2448. The surface characteristics of the samples were evaluated using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The cytotoxicity of the fabricated nanoTiO2/Ti-2448 was determined using MTT assays. The proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 osteoblasts cultured on nanoTiO2/Ti-2448 were compared with those cultured on Ti-2448. Disk-shaped implants were placed in Wistar rats. The histological sections were stained with haematoxylin and eosin (HE), and the histocompatibility was analysed at 4 and 12weeks post-implantation. Cylindrical implants were embedded in Japanese white rabbits, and the histological sections were stained with HE and anti-TGF-β1 to evaluate the histocompatibility and early osseointegration at 4, 12 and 26weeks post-implantation. NanoTiO2/Ti-2448 exhibited a rougher surface than did Ti-2448. NanoTiO2/Ti-2448 was determined to be non-cytotoxic. More osteoblasts and higher ALP activity were observed for nanoTiO2/Ti-2448 than Ti-2448 (p<0.05). Few inflammatory cells were detected around nanoTiO2/Ti-2448, and the expression of TGF-β1 on nanoTiO2/Ti-2448 peaked at earlier time than that on Ti-2448. The results indicate that the cytocompatibility and early osseointegration were enhanced by the nanoTiO2 coating. PMID:25579921

  17. Osteoconductivity and Hydrophilicity of TiO2 Coatings on Ti Substrates Prepared by Different Oxidizing Processes

    PubMed Central

    Yamamoto, Dai; Kawai, Ikki; Kuroda, Kensuke; Ichino, Ryoichi; Okido, Masazumi; Seki, Azusa

    2012-01-01

    Various techniques for forming TiO2 coatings on Ti have been investigated for the improvement of the osteoconductivity of Ti implants. However, it is not clear how the oxidizing process affects this osteoconductivity. In this study, TiO2 coatings were prepared using the following three processes: anodizing in 0.1 M H3PO4 or 0.1 M NaOH aqueous solution; thermal oxidation at 673 K for 2 h in air; and a two-step process of anodizing followed by thermal oxidation. The oxide coatings were evaluated using SEM, XRD, and XPS. The water contact angle on the TiO2 coatings was measured as a surface property. The osteoconductivity of these samples was evaluated by measuring the contact ratio of formed hard tissue on the implanted samples (defined as the RB-I value) after 14 d implantation in rats' tibias. Anatase was formed by anodizing and rutile by thermal oxidation, but the difference in the TiO2 crystal structure did not influence the osteoconductivity. Anodized TiO2 coatings were hydrophilic, but thermally oxidized TiO2 coatings were less hydrophilic than anodized TiO2 coatings because they lacked in surface OH groups. The TiO2 coating process using anodizing without thermal oxidation gave effective improvement of the osteoconductivity of Ti samples. PMID:23316128

  18. Effect of Al on the Wetting Behavior Between TiC x and Molten Ti-Al Alloys

    NASA Astrophysics Data System (ADS)

    Liu, Xuyang; Lv, Xuewei; Dong, Hongbiao; Li, Chunxin; Bai, Chenguang

    2015-10-01

    The wetting behavior and the interfacial reactions between TiC x substrate and molten Ti-Al alloys with different Al contents were studied using the Sessile Drop method at 1758 K (1485 °C) in argon atmosphere. It is found that the wettability and interface reaction products depend on Al content in the molten alloy. The initial contact angles between the molten Ti-Al alloy and TiC0.78 surface reduces from 110 to 80 deg when Al content in the alloy changes from 40 to 80 wt pct. The reduction in the initial contact angle is due to the decrease of surface tension of the molten Ti-Al alloys with increasing Al contents. The segregation of Al atoms to the surface occurred at all bulk concentrations of Ti-Al alloys. Al with lower surface tension tends to segregate on the surface of liquid Ti-Al alloy. In the spreading stage, the interfacial reaction led to the decrease in the contact angle. The adhesion in Ti-Al/TiC x system can be interpreted in terms of strong chemical interactions, which is greatly affected by the diffusion of C. The equilibrium contact angle was measured less than 10 deg. Finally, the reaction sequence at the Ti-Al melt and TiC x substrate interface is proposed.

  19. Effect of TiCl4 treatment on the refractive index of nanoporous TiO2 films

    NASA Astrophysics Data System (ADS)

    Lee, Jeeyoung; Lee, Myeongkyu

    2015-12-01

    We investigate the effect of TiCl4 treatment on the refractive index of a nanoporous TiO2 film. A nanoparticulate TiO2 film prepared on a glass substrate was immersed in a TiCl4 aqueous solution. The subsequent reaction of TiCl4 with H2O produces TiO2 and thus modifies the density and the refractive index of the film. With increasing TiCl4 concentration, the refractive index initially increased and then declined after being maximized (n = 2.02 at 633 nm) at 0.08 M concentration. A refractive index change as large as 0.45 could be obtained with the TiCl4 treatment, making it possible to achieve diffraction efficiency exceeding 80% in a diffraction grating-embedded TiO2 film. For high TiCl4 concentrations of 0.32 M and 0.64 M, the refractive index remained nearly unchanged. This was attributed to the limited permeability of high-viscosity TiCl4 solutions into the nanoporous films. The measured pore size distributions were in good agreement with the results of a diffraction analysis and refractive index measurement.

  20. Effect of TiO2 nano fillers on the electrical conductivity of PSAN/TiO2 polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Ningaraju, S.; Munirathnamma, L. M.; Kumar, K. V. Aneesh; Ravikumar, H. B.

    2016-05-01

    The microstructural characterization of Polystyrene co-acrylonitrile and Titanium dioxide (PSAN/TiO2) nanocomposites has been performed by Positron Annihilation Lifetime Spectroscopy. The decrease of positron lifetime parameters viz. o-Ps lifetime (τ3) and free volume size (Vf) up to 0.6 wt% of TiO2 is attributed to the filling of free volume holes by TiO2 nanoparticles. The increased free volume size (Vf) after 0.6 wt% of TiO2 indicates the formation of interface due to TiO2 nanoclusters. The variation of electrical conductivity at the lower and higher concentration of TiO2 in (PSAN/TiO2) nanocomposites is attributed to the blocking effect and space charge effect respectively.

  1. Anodic polarization behavior of Ti-Ni and Ti-6A1-4V in simulated physiological solutions.

    PubMed

    Speck, K M; Fraker, A C

    1980-10-01

    Anodic polarization measurements made in Hanks' physiological solution at 37 degrees C and a pH of 7.4 show titanium materials to be the most passive of the following metals: titanium, Ti-6A1-4V, Ti-Ni (memory alloy), MP35N (Co-Ni-Cr-Mo), Co-Cr-Mo, 316L stainless steel, and nickel. The influence of the amino acids, cysteine, and tryptophan on the corrosion behavior of Ti-Ni and Ti-6A1-4V was studied. Cysteine caused a lower breakdown potential for Ti-Ni, but it did not affect the breakdown of Ti-6A1-4V, although an increase in current density for Ti-6A1-4V was observed. Tryptophan produced no significant effects. PMID:6932415

  2. Sandwich SrTiO3/TiO2/H-Titanate nanofiber composite photocatalysts for efficient photocatalytic hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Liu, Yuanxu; Wang, Zhonglei; Wang, Wendong; An, Xiaoqiang; Mi, Shiyang; Tang, Junwang; Huang, Weixin

    2014-10-01

    SrTiO3/TiO2/H-Titanate nanofiber composites were synthesized through facile thermal treatment of Sr(OH)2 and H-titanate nanofibers in an ethanol/water solution and their photocatalytic activities for H2 evolution from a methanol/water solution under simulated solar irradiation were evaluated. TiO2/H-titanate nanofiber composites were acquired without Sr(OH)2 addition. At low Sr/Ti molar ratios, SrTiO3/TiO2/H-titanate nanofiber composites form. SrTiO3 nanoparticles were found to selectively grow on the surface of TiO2 nanoparticles, forming a unique SrTiO3-TiO2-H-titanate sandwich heterojunction. Upon increasing the Sr/Ti molar ratio, the fraction of TiO2 in the resultant composites decreases and eventually SrTiO3/H-titanate nanofiber composites form. SrTiO3/TiO2/H-titanate nanofiber composites are significantly more photocatalytically active than SrTiO3/H-titanate nanofiber and TiO2/H-titanate nanofiber composites due to the mitigated charge recombination and the accumulation of photo-excited electrons on the photocatalytically active TiO2 component. These results demonstrate an effective strategy of multi-heterojunctions with both appropriately-aligned band structures and appropriately-arranged composite structures to fabricate efficient composite photocatalysts.

  3. Inactivation and mineralization of aerosol deposited model pathogenic microorganisms over TiO2 and Pt/TiO2.

    PubMed

    Kozlova, E A; Safatov, A S; Kiselev, S A; Marchenko, V Yu; Sergeev, A A; Skarnovich, M O; Emelyanova, E K; Smetannikova, M A; Buryak, G A; Vorontsov, A V

    2010-07-01

    Air disinfection from bacteria and viruses by means of photocatalytic oxidation is investigated with microorganisms loaded over photocatalysts' films from aerosols. Deposition method and equipment have been developed to load Mycobacterium smegmatis , Bacillus thuringiensis , vaccinia virus, and influenza A (H3N2) virus on slides with undoped TiO(2) and platinized sulfated TiO(2) (Pt/TiO(2)). Inactivation dynamics was measured under UVA irradiation and in the dark. About 90% inactivation is reached in 30 min irradiation on TiO(2) and from 90 to 99.8% on Pt/TiO(2). The first-order inactivation rate coefficient ranged from 0.18 to 0.03 min(-1), over Pt/TiO(2) being higher than on TiO(2) for all microorganisms except Bacillus thuringiensis. The photocatalytic mineralization of Bacillus thuringiensis was performed on TiO(2) and Pt/TiO(2) with different photocatalyst and microorganism loadings. Completeness of mineralization depended on the TiO(2) to bacteria mass ratio. The rate of the photocatalytic carbon dioxide production grows with both the cell mass increase and the photocatalyst mass increase. Pt/TiO(2) showed increased rate of mineralization as well as of the inactivation likely due to a better charge carrier separation in the doped semiconductor photocatalyst. The results demonstrate that photocatalytic filters with deposited TiO(2) or Pt/TiO(2) are able to inactivate aerosol microorganisms and completely decompose them into inorganic products and Pt/TiO(2) provides higher disinfection and mineralization rates. PMID:20521809

  4. Corrosion behavior of the embedded layer with nanometer phase in Ti and /Ti+C-implanted steel

    NASA Astrophysics Data System (ADS)

    Zhang, Tonghe; Wu, Yuguang; Zhang, Huixing; Deng, Zhiwei; Zhou, Gu; Liang, Hong; Ma, Furong; Zhang, Xiaoji; Wang, Xiaoyan

    2000-06-01

    Ti and Ti + C ions were implanted into H13 steel, the cross-sections of the samples were observed by transmission electron microscope (TEM). The results show that the structure of the implanted layer has greatly changed. The layer, embedded with nanometer phase of FeTi 2, TiC and Fe-C compound, is formed in Ti and Ti + C ion-implanted layer. The thickness of the embedded layer is greater than that of the corresponding ion range. The structure of the double ion-implanted layers is obviously different. The wear resistance and hardness of Ti or Ti + C-implanted H13 steel increased, and the friction coefficient decreased. This indicates that unique resistance for wear and corrosion can be obtained. An even higher corrosion resistance has been found, as the layer with an embedded structure was formed in Ti or Ti + C-implanted H13 steel. The results of electrochemical measurement show that the corrosion current density decreases obviously with increase of ion dose. The corrosion current density of Ti-implanted steel with a dose 1.3×10 18 cm -2 is 5-13% of that of unimplanted steel. The corrosion behavior of Ti + C dual implantation could be further improved; the corrosion current density is 1.2% of that of non-implanted samples. The corrosion trace could not be observed on the annealing sample by scanning electron microscope (SEM), after multi-sweep cyclic voltammetry (CV) of 40 cycles were performed on it. Finally, the modification mechanism of Ti or Ti + C-implanted H13 steel is discussed.

  5. The underlying biological mechanisms of biocompatibility differences between bare and TiN-coated NiTi alloys.

    PubMed

    Lifeng, Zhao; Yan, Hong; Dayun, Yang; Xiaoying, Lü; Tingfei, Xi; Deyuan, Zhang; Ying, Hong; Jinfeng, Yuan

    2011-04-01

    TiN coating has been demonstrated to improve the biocompatibility of bare NiTi alloys; however, essential biocompatibility differences between NiTi alloys before and after TiN coating are not known so far. In this study, to explore the underlying biological mechanisms of biocompatibility differences between them, the changes of bare and TiN-coated NiTi alloys in surface chemical composition, morphology, hydrophilicity, Ni ions release, cytotoxicity, apoptosis, and gene expression profiles were compared using energy-dispersive spectroscopy, scanning electron microscopy, contact angle, surface energy, Ni ions release analysis, the methylthiazoltetrazolium (MTT) method, flow cytometry and microarray methods, respectively. Pathways binding to networks and real-time polymerase chain reaction (PCR) were employed to analyze and validate the microarray data, respectively. It was found that, compared with the bare NiTi alloys, TiN coating significantly decreased Ni ions content on the surfaces of the NiTi alloys and reduced the release of Ni ions from the alloys, attenuated the inhibition of Ni ions to the expression of genes associated with anti-inflammatory, and also suppressed the promotion of Ni ions to the expression of apoptosis-related genes. Moreover, TiN coating distinctly improved the hydrophilicity and uniformity of the surfaces of the NiTi alloys, and contributed to the expression of genes participating in cell adhesion and other physiological activities. These results indicate that the TiN-coated NiTi alloys will help overcome the shortcomings of NiTi alloys used in clinical application currently, and can be expected to be a replacement of biomaterials for a medical device field. PMID:21441653

  6. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    NASA Astrophysics Data System (ADS)

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; Hoffman, Elizabeth N.; Kohse, Gordon; Sindelar, Robert L.; Barsoum, Michel W.

    2016-01-01

    Herein we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation - up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ± 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 × 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.

  7. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    DOE PAGESBeta

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; Hoffman, Elizabeth N.; Kohse, Gordon; Sindelar, Robert L.; Barsoum, Michel W.

    2015-10-23

    Here, we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation – up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ±more » 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 x 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.« less

  8. PIRAC Ti nitride coated Ti-6AI-4V head against UHMWPE acetabular cup-hip wear simulator study.

    PubMed

    Gutmanas, E Y; Gotman, I

    2004-04-01

    Wear behaviour of TiN(titanium nitride)-coated Ti and Ti-6AI-4V alloy against UHMW polyethylene was studied in hip simulation test. Ti alloys possess an excellent combination of mechanical properties and biocompatibility, however, they suffer from inadequate wear resistance. Thus, their use as articulating components of total joint replacements requires surface hardening, e.g. by TiN. Thirty-two millimetre diameter cp-Ti and Ti-6AI-4V femoral heads were coated with several micrometre thick TiN layers employing an original PIRAC nitriding method based on interaction of Ti alloy substrate with highly reactive monatomic nitrogen. The heads were tested against UHMWPE cups at 37 degrees C in Ringer's solution or in distilled water. Simulator tests were performed at peak pressures of 1.5 and 2.0 MPa in a constant rotation mode at the frequency of 1.5 Hz. The wear of UHMWPE was estimated by weight loss, and the worn metallic and polyethylene surfaces were examined in SEM. The wear rate of UHMWPE cups articulating against PIRAC coated Ti and Ti-6AI-4V after up to 4 x 10(6) cycles was significantly lower than that of UHMWPE articulating against 316L stainless steel. No delamination of TiN coatings was observed after 4 x 10(6) cycles. These results suggest that TiN PIRAC coating on Ti-6AI-4V heads could minimise the wear of total hip replacements without compromising the mechanical properties of the femoral component. PMID:15332594

  9. Ferroelectricity in (BaTiO3)n/(SrTiO3)m Superlattices Containing as Few as one BaTiO3 Layer (n=1)

    NASA Astrophysics Data System (ADS)

    Schlom, Darrell

    2007-03-01

    The question of how thin a ferroelectric can be and still be ferroelectric has been the source of an intensive research effort over the past decade. Several studies, both theoretical and experimental, have concluded that with appropriate boundary conditions ferroelectricity can exist in superlattices containing BaTiO3 or PbTiO3 layers as thin as one unit cell. In this talk I will show the results of experiment and theory for BaTiO3/SrTiO3 superlattices grown by reactive molecular-beam epitaxy (MBE) on three different substrates: TiO2-terminated (001) SrTiO3, (110) DyScO3, and (110) GdScO3. With the aid of reflection high-energy electron diffraction (RHEED), precise single-monolayer doses of BaO, SrO, and TiO2 were deposited sequentially to create commensurate BaTiO3/SrTiO3 superlattices with a variety of periodicities. The superlattices consist of an n unit-cell-thick slab of BaTiO3 followed by an m unit-cell-thick slab of SrTiO3, which are designated [(BaTiO3)n/(SrTiO3)m]q, where q is the number of times the bilayer is repeated. X-ray diffraction (XRD) measurements exhibit clear superlattice peaks and the narrowest rocking curves ever reported for oxide superlattices. High-resolution transmission electron microscopy reveals nearly atomically abrupt interfaces. UV Raman results show that the BaTiO3 in these [(BaTiO3)n/(SrTiO3)m]q superlattices is tetragonal and the SrTiO3 is polar due to strain. Temperature-dependent UV Raman and XRD reveal the paraelectric-to-ferroelectric transition temperature (TC). Our results* demonstrate (1) that [(BaTiO3)n/(SrTiO3)m]q superlattices containing as few as one strained BaTiO3 layer (n=1) are ferroelectric and (2) the sensitivity of TC to the boundary conditions. Comparisons to ab initio and phase-field modeling of the properties of these [(BaTiO3)n/(SrTiO3)m]q ferroelectric superlattices will be made and the importance of strain demonstrated. In addition to probing finite size effects and the importance of mechanical boundary

  10. Spectral Synthesis of TiO Lines

    NASA Astrophysics Data System (ADS)

    Valenti, Jeff A.; Piskunov, Nikolai; Johns-Krull, Christopher M.

    1998-05-01

    We explore the extent to which current titanium oxide (TiO) line data and M dwarf model atmospheres can be used to reproduce an R = 120,000 optical spectrum of the relatively inactive star Gliese 725B (M3.5 V). We find that tabulated TiO wavelengths have errors large enough to complicate line identification, especially for transitions involving higher vibrational states. We determine empirical wavelength corrections for 12 strong γ-bands near 6680 and 7090 Å. For the sequence of orbital quantum numbers, J, within any one of these bands, our observations confirm the predicted line spacing, thereby validating the rotational constants for low vibrational levels. However, the predicted wavelengths have zero-point errors that differ for each overlapping band. Next, we compare observed and synthetic spectra near 8463 Å, where an ε Q3 0-0 band head is expected, demonstrating that the electronic oscillator strength of 0.014 advocated by Jørgensen is too large by at least a factor of 5. This has a minor effect on the structure of theoretical model atmospheres. Using our empirically corrected TiO wavelengths, we compute a grid of synthetic spectra for Allard & Hauschildt models spanning a range in effective temperature (Teff), surface gravity (log g), and metallicity ([M/H]). Interpolating in this grid of synthetic spectra, we simultaneously fit observations of the TiO band head region near 7088 Å and five Ti I and Fe I lines near 8683 Å. For Gl 725B, we find Teff = 3170 +/- 71 K, log g = 4.77 +/- 0.14, [M/H] = -0.92 +/- 0.07, and vmac = 1.1 +/- 0.7 km s-1. We show that by using both atomic and molecular lines as constraints, systematic uncertainties in derived stellar parameters can be reduced. These parameters are consistent with published values obtained by other means, but more stringent tests would be useful. In the Appendix, we tabulate wavelengths, identifications, relative line strengths, and other properties of the strongest band heads in the α, β, γ,

  11. Structural and Morphological Difference Between Ti/TiN/TiCN Coatings Grown in Multilayer and Graded Form

    SciTech Connect

    Restrepo, E.; Baena, A.; Agudelo, C.; Castillo, H.; Devia, A.; Marino, A.

    2006-12-04

    Thin films can be grown in super-lattice, multilayers and graded form, having each one advantages and disadvantages. The difference between multilayer and graded coatings is the interface. In multilayers the interface is abrupt and in graded coatings it is diffuse. The interface influences many chemical and physical properties of the materials, and its choice depends on the application. Graded coatings have the advantage of having gradual properties such as thermal expansion coefficient and lattice parameter, avoiding adherence problems due to good match between their component materials. In this work the comparison between some properties of coatings grown as multilayer and graded is performed. The materials are produced using the sputtering DC technique because of its facility to control the deposition parameters and generate a slow growth. The target is a disc of titanium and the samples are made of stainless steel 304. The working gases are argon, nitrogen and methane, which are mixed according to the material to be produced, i.e. Ti layer is grown with argon, the TiN film is produced with a mixture of argon and nitrogen, and the TiCN material is obtained mixing argon, nitrogen and methane. These materials are characterized with AFM in order to determine grain size and with XPS studying the chemical composition and performing depth profiles.

  12. Mechanical properties and biocompatibility of the sputtered Ti doped hydroxyapatite.

    PubMed

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

    2016-10-01

    The hydroxyapatite enriched with Ti were prepared as possible candidates for biomedical applications especially for implantable devices that are in direct contact to the bone. The hydroxyapatites with different Ti content were prepared by RF magnetron sputtering on Ti-6Al-4V alloy using pure hydroxyapatite and TiO2 targets. The content of Ti was modified by changing the RF power fed on TiO2 target. The XPS and FTIR analyses revealed the presence of hydroxyapatite structure. The hardness and elastic modulus of the hydroxyapatite were increased by Ti addition. After 5 days of culture, the cell viability of the Ti-6Al-4V was enhanced by depositing with undoped or doped hydroxyapatite. The Ti additions led to an increase in cell viability of hydroxyapatite, after 5 days of culture. The electron microscopy showed the presence of more cells on the surface of Ti-enriched hydroxyapatite than those observed on the surface of the uncoated alloys or undoped hydroxyapatite. PMID:27450034

  13. The Ti environment in natural hibonite: XANES spectroscopy and computer modelling

    NASA Astrophysics Data System (ADS)

    Kravtsova, Antonina N.; Soldatov, Alexander V.; Walker, Andrew M.; Berry, Andrew J.

    2016-05-01

    The local atomic structure around Ti in Ti-bearing hibonite (CaAl12O19) was studied using X-ray absorption near-edge structure (XANES) spectroscopy and computer modelling. Structural models of the direct substitution of Al by Ti3+, Al by Ti4+ charge balanced by the coupled substitution of Mg2+ for Al, and small Ti clusters were considered. The Ti K-XANES spectra of natural hibonite with different Ti concentration were recorded. Theoretical Ti K- XANES spectra for structural models of hibonite were calculated. It was shown that the theoretical Ti K-XANES spectra for a model with Ti at the five-coordinated M2 site are in agreement with the experimental XANES spectra of hibonite with low concentrations of Ti, while the theoretical spectra for a structural model of clustered Ti are in agreement with the experimental spectra of hibonite with higher Ti contents.

  14. Gas nitriding and subsequent oxidation of Ti-6Al-4V alloys

    PubMed Central

    2012-01-01

    Ti-6Al-4V alloys consisting of α-Ti grains and intergranular β-Ti islands were nitrided at 850°C for 1 to 12 h under a nitrogen pressure of 1 Pa. With increasing nitriding time, the Ti-N compound layer became thicker, and the α-Ti diffusion zone containing dissolved nitrogen became wider. In the Ti-N compound layer, the initially formed Ti2N became TiN as the nitriding progressed. The nitride layers were oxidized to rutile-TiO2 after oxidation at 700°C for 10 h in air. PMID:22221679

  15. Gas nitriding and subsequent oxidation of Ti-6Al-4V alloys.

    PubMed

    Lee, Dong Bok; Pohrelyuk, Iryna; Yaskiv, Oleh; Lee, Jae Chun

    2012-01-01

    Ti-6Al-4V alloys consisting of α-Ti grains and intergranular β-Ti islands were nitrided at 850°C for 1 to 12 h under a nitrogen pressure of 1 Pa. With increasing nitriding time, the Ti-N compound layer became thicker, and the α-Ti diffusion zone containing dissolved nitrogen became wider. In the Ti-N compound layer, the initially formed Ti2N became TiN as the nitriding progressed. The nitride layers were oxidized to rutile-TiO2 after oxidation at 700°C for 10 h in air. PMID:22221679

  16. Simultaneous synthesis of TiB2-TiC nanocomposites through MASHS method and investigation of activation of the raw materials on this process

    NASA Astrophysics Data System (ADS)

    Aminikia, Behzad

    2012-09-01

    In this research TiB2-TiC Nanocomposite was fabricated by SHS of mechanically milled powders. Ti and B4C as starting materials were milled for 1, 3 and 6 h then pressed to form pellets. Green compacts were placed in a tube furnace which had been preheated to 1200 °C in argon atmosphere, for synthesis. TiC and TiB2 were not formed during milling process. The increasing of milling time helped significantly to improve the formation of TiC and TiB2. From TEM picture, it could be seen that typical TiB2 and TiC crystallites were uniform particles. The crystallite sizes of TiB2 and TiC in the composite based on milled powder for 6 h was calculated 42 and 73 nm respectively which are confirmed by the TEM results.

  17. TiO2 nanosized powders by TiCl4 laser pyrolysis

    NASA Astrophysics Data System (ADS)

    Alexandrescu, R.; Dumitrache, F.; Morjan, I.; Sandu, I.; Savoiu, M.; Voicu, I.; Fleaca, C.; Piticescu, R.

    2004-05-01

    Nano-TiO2 powders were successfully prepared by laser pyrolysis of TiCl4 (vapours). Alternatively, air and nitrous oxide were used as oxygen precursors. C2H4 was used as an energy transfer agent. The underlying phenomena for this photon-based molecular nanotechnology are discussed. For the present report, different titania nanosized powder batches were obtained by variation of the oxidizer nature and TiCl4 precursor flows. X-ray diffraction, transmission electron microscopy, electron energy loss spectroscopy, x-ray dispersive energy analysis, and IR and Raman spectrometry have been used to analyse the nanostructures and morphologies of the as-synthesized powders. Medium and high resolution TEM analyses indicate mean grain sizes between 12 and 28 nm. The different characterization techniques suggest that in the obtained anatase and rutile mixture the fraction of rutile phase depends on the nature of the oxygen precursor. At low TiCl4 flows, no chlorine contamination was detected in the reaction product. Further examination of the influence of other important system parameters will open new possibilities for titania preparation by the laser pyrolysis of TiCl4.

  18. Oxygen Octahedral Rotations in BaTiO3/CaTiO3 Superlattices

    NASA Astrophysics Data System (ADS)

    Cosgriff, Margaret; Chen, Pice; Corey, Nathaniel; Wu, Xifan; Mehta, Apurva; Tajiri, Hiroo; Lee, Ho Nyung; Evans, Paul

    2013-03-01

    Complex oxide superlattices have a wide range of electronic and magnetic properties, which are affected by the structure of the interfaces between different components of the superlattice. The magnitude, coherence, and electric field response of oxygen displacements in three different BaTiO3/CaTiO3 superlattice compositions are measured using x-ray diffraction. The displacements are greater in compositions with more consecutive CaTiO3 layers. The pattern of layer-by-layer alternating displacements is coherent over less than two superlattice unit cells. The net in-phase rotation of the oxygen octahedra gives rise to an x-ray reflection at (3/2 1/2 1). Density functional theory calculations for a 2(BaTiO3) /4(CaTiO3) composition predict a decrease in displacements of oxygen octahedra between barium and calcium layers when an electric field is applied, causing an intensity increase in this reflection. We found the intensity of this reflection for this composition increases by 1.6% when a 12.5 V pulse is applied, a weaker response than the 11% increase predicted. When a 20 V pulse is applied, the reflection intensity actually decreases by 3%, indicating a more complicated response.

  19. N and Ti adatom dynamics on stoichiometric polar TiN(111) surfaces

    NASA Astrophysics Data System (ADS)

    Sangiovanni, D. G.; Tasnádi, F.; Hultman, L.; Petrov, I.; Greene, J. E.; Chirita, V.

    2016-07-01

    We use molecular dynamics (MD) based on the modified embedded atom method (MEAM) to determine diffusion coefficients and migration pathways for Ti and N adatoms (Tiad and Nad) on TiN(111). The reliability of the classical model-potential is verified by comparison with density functional theory (DFT) results at 0 K. MD simulations carried out at temperatures between 600 and 1800 K show that both Tiad and Nad favor fcc surface sites and migrate among them by passing through metastable hcp positions. We find that Nad species are considerably more mobile than Tiad on TiN(111); contrary to our previous results on TiN(001). In addition, we show that lattice vibrations at finite temperatures strongly modify the potential energy landscape and result in smaller adatom migration energies, Ea = 1.03 for Tiad and 0.61 eV for Nad, compared to 0 K values Ea0K = 1.55 (Tiad) and 0.79 eV (Nad). We also demonstrate that the inclusion of dipole corrections, neglected in previous DFT calculations, is necessary in order to obtain the correct formation energies for polar surfaces such as TiN(111).

  20. Interface enhanced functionalities in BaTiO3/CaTiO3 superlattices

    NASA Astrophysics Data System (ADS)

    Wu, Xifan

    2014-03-01

    Interface engineering of oxide thin films has led to the development of many intriguing physical properties and new functionalities, in which the oxygen rotation and tilting take an crucial role. The oxygen octahedral tilt has been considered to be a coherent motion in the oxide thin-films, based on which the tilt is often neglected in the modeling of ABO3 superlattices. However, combined with state-of-art experimental high-resolution electron microscopic image, our first-principles results clearly show that oxygen octahedral tilt should be more appropriately defined by the tilting angles of two individual pyramids. Each pyramid will tilt rather independently as a function of its local chemical environment. Considering the oxygen octahedral rotation at the same time, the new picture of oxygen octahedral tilting will induce a novel interface effect, in which an unstable structure in bulk CaTiO3 will be stabilized at the interface in BaTiO3/CaTiO3 superlattice. This novel interface effect induces large polarizations both in-plane and out-of-plane with a corresponding enhanced piezoelectricity. The above scenario successfully explains the recent experimental discoveries in BaTiO3/CaTiO3 superlattices by H. Lee's and P. Evan's groups respectively.

  1. Amorphization of Ti1- x Mn x

    NASA Astrophysics Data System (ADS)

    Chu, B.-L.; Chen, C.-C.; Perng, T.-P.

    1992-08-01

    Three amorphous Ti1- x Mn x alloy powders, with x = 0.4, 0.5, and 0.6, were prepared by mechanical alloying (MA) of the elemental powders in a high-energy ball mill. The amorphous powders were characterized by X-ray diffraction (XRD) and high-resolution transmission elec- tron microscopy (HRTEM). The crystallization temperatures for these alloys detected by dif- ferential scanning calorimetry (DSC) varied from 769 to 830 K. The calculated enthalpies of mixing in these amorphous phases are relatively small compared with those for other Ti-base binary alloys. The criteria for solid-state amorphization reaction are examined. It is suggested that the kinetics of nucleation and growth favors the formation of the amorphous phases and the supply of atoms for nucleation and growth is predominantly through the defective regions induced by MA.

  2. 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.

  3. Ti-rich komatiites from northern Norway

    NASA Astrophysics Data System (ADS)

    Barnes, Sarah-Jane; Often, Morten

    1990-06-01

    Komatiites of the Karasjok Greenstone Belt, northern Norway, show two unusual features: they have certain compositional differences compared with other komatiites, and they are largely volcaniclastic in origin. Their geological setting suggests that the komatiites were crupted into shallow water, thus permitting phreatomagmatic eruption, in a small ocean basin that opened in the Baltic Shield. The major oxides (except for TiO2), the trace elements Y, Sc, V, heavy rare earth elements (HREE), Cr, Co, Ni and the platinum group elements (PGE) cover similar ranges to those observed in other komatiites, but TiO2, Sm, Zr and Hf (Ti-associated elements, TAE) are enriched compared with abundances commonly reported for komatiites. Thus, the Karasjok komatiites have interelement ratios 2 to 3 times greater than chondritic between the TAE and the HREE, PGE, Sc, V, Y, Al (HRE-associated elements, HAE). The light rare earth elements (LREE), Ta and Th are enriched in some samples relative to Ti, Sm, Zr, and Hf, but are depleted in others. One group of rocks that is similar to the Karasjok komatiites both in terms of geological setting and geochemistry is the Baffin Bay picrites. The reason for the high concentrations of TAE in the Karasjok komatiites could be that they formed at lower degrees of partial melting than most komatiites. The greater-than-chondritic TAE/HAE ratios indicate that garnet was a residual phase during their formation, requiring that the melt formed at a pressure greater than 40 kb. A model involving decompression melting of a mantle plume rising in a rifting environment, can explain the main features of the Karasjok komatiites.

  4. TiME - The Titan Mare Explorer

    NASA Astrophysics Data System (ADS)

    Stofan, E.; Lorenz, R.; Lunine, J.; Bierhaus, E. B.; Clark, B.; Mahaffy, P. R.; Ravine, M.

    The Titan Mare Explorer (TiME) is a Discovery-class mission concept that underwent a detailed Phase A study in 2011-2012. The mission would splashdown a capsule on Titan's ethane sea Ligeia Mare as early as the summer of 2023, and would spend multiple Titan days performing science measurements and transmitting data directly back to Earth. This paper reviews briefly the mission concept.

  5. Minimum ignition energy of nano and micro Ti powder in the presence of inert nano TiO₂ powder.

    PubMed

    Chunmiao, Yuan; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

    2014-06-15

    The inerting effect of nano-sized TiO2 powder on ignition sensitivity of nano and micro Ti powders was investigated with a Mike 3 apparatus. "A little is not good enough" is also suitable for micro Ti powders mixed with nano-sized solid inertants. MIE of the mixtures did not significantly increase until the TiO2 percentage exceeded 50%. Nano-sized TiO2 powders were ineffective as an inertant when mixed with nano Ti powders, especially at higher dust loadings. Even with 90% nano TiO2 powder, mixtures still showed high ignition sensitivity because the statistic energy was as low as 2.1 mJ. Layer fires induced by ignited but unburned metal particles may occur for micro Ti powders mixed with nano TiO2 powders following a low level dust explosion. Such layer fires could lead to a violent dust explosion after a second dispersion. Thus, additional attention is needed to prevent metallic layer fires even where electric spark potential is low. In the case of nano Ti powder, no layer fires were observed because of less flammable material involved in the mixtures investigated, and faster flame propagation in nanoparticle clouds. PMID:24797905

  6. Thermal Stability of Ge2Sb2Te5 in Contact with Ti and TiN

    NASA Astrophysics Data System (ADS)

    Venugopal, Vijayaharan A.; Ottaviani, Giampiero; Bresolin, Camillo; Erbetta, Davide; Modelli, Alberto; Varesi, Enrico

    2009-10-01

    The thermal stability of a Ge2Sb2Te5 chalcogenide layer in contact with titanium and titanium nitride metallic thin films has been investigated mainly using x-ray diffraction and elastic nuclear backscattering techniques. Without breaking vacuum, Ti and TiN have been deposited on Ge2Sb2Te5 material using magnetron sputtering. Thermal treatments have been performed in a 10-7 mbar vacuum furnace. On annealing up to 450°C, the TiN metallic film does not interact with the chalcogenide film, but at the same time adhesion problems and instabilities in contact resistance arise. To improve the adhesion and eventually stabilize the contact resistance, an interfacial Ti layer has been considered. At 300°C, a TiTe2 compound is formed by interacting with Te segregated from the Ge2Sb2Te5 layer. At higher temperatures, the Ti layer decomposes the chalcogenide film, forming several compounds tentatively identified as GeTe, Ge3Ti5, Ge5Ti6, TiTe2,, and Sb2Te3. It has been found that the properties of the Ge2Sb2Te5 film can be retained by controlling the decomposition rate of the chalcogenide layer, which is achieved by providing a limited supply of Ti and/or by depositing a Te-rich Ge2Sb2Te5 film.

  7. Modeling creep deformation of a two-phase TiAl/Ti[sub 3]Al alloy with a lamellar microstructure

    SciTech Connect

    Bartholomeusz, M.F. ); Wert, J.A. . Dept. of Materials Science and Engineering)

    1994-10-01

    A two-phase TiAl/Ti[sub 3]Al alloy with a lamellar microstructure has been previously shown to exhibit a lower minimum creep rate than the minimum creep rates of the constituent TiAl and Ti[sub 3]Al single-phase alloys. Fiducial-line experiments described in the present article demonstrate that the creep rates of the constituent phases within the two-phase TiAl/Ti[sub 3]Al lamellar alloy tested in compression are more than an order of magnitude lower than the creep rates of single-phase TiAl and Ti[sub 3]Al alloys tested in compression at the same stress and temperature. Additionally, the fiducial-line experiments show that no interfacial sliding of the phases in the TiAl/Ti[sub 3]Al lamellar alloy occurs during creep. The lower creep rate of the lamellar alloy is attributed to enhanced hardening of the constituent phases within the lamellar microstructure. A composite-strength model has been formulated to predict the creep rate of the lamellar alloy, taking into account the lower creep rates of the constituent phases within the lamellar microstructure. Application of the model yields a very good correlation between the predicted an experimentally observed minimum creep rates over moderate stress and temperature ranges.

  8. Modeling creep deformation of a two-phase TiAI/Ti3Al alloy with a lamellar microstructure

    NASA Astrophysics Data System (ADS)

    Bartholomeusz, Michael F.; Wert, John A.

    1994-10-01

    A two-phase TiAl/Ti3Al alloy with a lamellar microstructure has been previously shown to exhibit a lower minimum creep rate than the minimum creep rates of the constituent TiAl and Ti3Al single-phase alloys. Fiducial-line experiments described in the present article demonstrate that the creep rates of the constituent phases within the two-phase TiAl/Ti3Al lamellar alloy tested in compression are more than an order of magnitude lower than the creep rates of single-phase TiAl and Ti3Al alloys tested in compression at the same stress and temperature. Additionally, the fiducial-line experiments show that no interfacial sliding of the phases in the TiAl/Ti3Al lamellar alloy occurs during creep. The lower creep rate of the lamellar alloy is attributed to enhanced hardening of the constituent phases within the lamellar microstructure. A composite-strength model has been formulated to predict the creep rate of the lamellar alloy, taking into account the lower creep rates of the constituent phases within the lamellar micro-structure. Application of the model yields a very good correlation between predicted and experimentally observed minimum creep rates over moderate stress and temperature ranges.

  9. Local structure of spin Peierls compound TiPO4: 47/49Ti and 31P NMR study

    NASA Astrophysics Data System (ADS)

    Stern, Raivo; Heinmaa, Ivo; Leitmäe, Alexander; Joon, Enno; Tsirlin, Alexander; Kremer, Reinhard; Glaum, Robert

    TiPO4 structure is made of slightly corrugated TiO2 ribbon chains of edge-sharing TiO6 octahedra. The almost perfect 1D spin 1/2 Ti3 + chains are well separated by PO4 tetrahedra. By magnetic susceptibility and MAS-NMR measurements [1] it was shown that TiPO4 has nonmagnetic singlet ground state with remarkably high Spin-Peierls (SP) transition temperature. The high-T magnetic susceptibility of TiPO4 follows well that of a S =1/2 Heisenberg chain with very strong nearest-neighbor AF spin-exchange coupling constant of J =965K. On cooling TiPO4 shows two successive phase transitions at 111K and 74K, with incommensurate (IC) SP phase between them. We studied local structure and dynamics in TiPO4 single crystal using 47/49Ti and 31P NMR in the temperature range 40K to 300K, and determined the principal values and orientation of the magnetic shift tensors for 31P and 47,49Ti nuclei. Since 47,49Ti (S =5/2 and S =7/2, respectively) have quadrupolar moments, we also found the principal axis values and orientations of the electric field gradient (efg) tensor in SP phase and at 295K. In SP phase the structure contains 2 magnetically inequivalent P sites and only one Ti site. From the T-dependence of the relaxation rate of 31P and 47Ti nuclei we determined activation energy Ea = 550 K for spin excitations in SP phase. J. Law et al ., PRB 83, 180414(R) (2011).

  10. Novel functionalization of Ti-V alloy and Ti-II using atomic layer deposition for improved surface wettability.

    PubMed

    Patel, Sweetu; Butt, Arman; Tao, Qian; Rossero A, Jorge Iván; Royhman, Dmitry; Sukotjo, Cortino; Takoudis, Christos G

    2014-03-01

    Surface wettability characteristics of commercially pure titanium (CP-Ti/Ti-II) and titanium Grade 5 alloy (Ti-6Al-4V/Ti-V) with 10nm-thick atomic layer deposited (ALD) TiO2 from Tetrakis DiEthyl Amino Titanium and water vapor were studied in conjunction with cleaning steps before and after the ALD treatment. The wettability characteristics of rough Ti-II and Ti-V samples were investigated after each step, that is, as received, after de-ionized (DI) water rinse followed by N2 drying, sonication in methanol, ALD treatment, and post-ALD DI water rinse. Samples without ALD or cleaning treatments were hydrophobic to variable extents, depending on exposure to different environments, surface impurities, roughness, and aging. Surface treatments reported in the literature resulted in hydrophilic/hydrophobic surfaces likely due to organic and/or inorganic impurities. In this study, (i) it is established that it is critically important to probe surface wettability after each substrate treatment; (ii) both Ti-II and Ti-V surfaces are found to become more hydrophilic after each one of the sequential treatments used; and (iii) independently of the initial wettability characteristics of Ti-II and Ti-V surfaces, the aforementioned treatments result in a water contact angle well below 10°, which is an important factor in cellular response. X-ray photoelectron spectroscopy of ALD titania films indicated trace impurities in them. Grazing incidence X-ray diffraction suggested amorphous ALD TiO2 at 200 °C; anatase TiO2 was obtained with as little as 5 min annealing at 600 °C in nitrogen. PMID:24384144

  11. Electron Impact Excitation Of Ti XIX

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, F. P.

    2012-05-01

    Emission lines of Ti XIX are important for the modeling and diagnostics of lasing, fusion and astrophysical plasmas, for which atomic data are required for a variety of parameters, such as energy levels, radiative rates (A- values), and excitation rates or equivalently the effective collision strengths (Υ), which are obtained from the electron impact collision strengths (Ω). Experimentally, energy levels are available for Ti XIX on the NIST website, but there is paucity for accurate collisional atomic data. Therefore, here we report a complete set of results (namely energy levels, radiative rates, and effective collision strengths) for all transitions among the lowest 98 levels of Ti XIX. These levels belong to the (1s2) 2s2, 2s2p, 2p2, 2s3l, 2p3l, 2s4l, and 2p4l configurations. Finally, we also report the A- values for four types of transitions, namely electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2), because these are also required for plasma modeling. For our calculations of wavefunctions, we have adopted the fully relativistic GRASP code, and for the calculations of Ω, the Dirac atomic R-matrix code (DARC) of PH Norrington and IP Grant. Additionally, parallel calculations have also been performed with the Flexible Atomic Code (FAC) of Gu, so that all atomic parameters can be rigorously assessed for accuracy.

  12. Rapid synthesis of ternary carbide Ti3SiC2 through pulse-discharge sintering technique from Ti/Si/TiC powders

    NASA Astrophysics Data System (ADS)

    Zhang, Z. F.; Sun, Z. M.; Hashimoto, H.

    2002-11-01

    Ti/Si/TiC powders with molar ratios of 1:1:2 (M1) and 2:2:3 (M2) were prepared for the synthesis of a ternary carbide Ti3SiC2 by using the mixture method for 24 hours in an Ar atmosphere. The synthesis process was conducted at 1200 °C to 1400 °C under a pressure of 50 MPa, using the pulse-discharge sintering (PDS) technique. After sintering, the phase constituents and microstructures of the samples were analyzed by X-ray diffraction (XRD) technique and observed by optical microscopy and scanning electron microscopy. The results showed that the phases in all the samples consisted of Ti3SiC2 and small amounts of TiC, and the optimum sintering temperature was found to be in the relatively low range of 1250 °C to 1300 °C. By the standard additive method, the relative content of Ti3SiC2 was calculated. For the M1 samples, the lowest TiC content can be only decreased to about 3 to 4 wt pct, whereas the content of Ti3SiC2 in the M2 samples is always lower than that in the M1 samples. When the M2 powder was sintered at 1300 °C for 8 to 240 minutes, the TiC peaks were found to show a very low intensity, and the corresponding content of Ti3SiC2 was calculated to be higher than 99 wt pct. The grain size of Ti3SiC2 increased from 5 to 10 µm to 80 to 100 µm in the entire applied sintering temperature range. The relative density of the M2 samples was measured to be higher than 99 pct at sintering temperatures above 1275 °C. It indicates that the PDS technique can rapidly synthesize high-content Ti3SiC2 from the Ti/Si/TiC powders in a relatively low temperature range.

  13. Photo response of silver-TiO2 film.

    PubMed

    Viernes, M A J; Mahinay, C L S; Villamayor, M M S; Ramos, H J

    2014-02-01

    Silver and TiO2 films were deposited on glass substrates via the plasma sputter type negative ion source and a compact planar magnetron, respectively. A silver target was biased and is sputtered by argon plasma for 30 min. TiO2 was deposited by sputtering a titanium disk and introducing oxygen in a 1:13 ratio with argon plasma for 2 h. The resulting composite films (silver on TiO2 and TiO2 on silver) were analyzed by its transmissivity in the UV-VIS region showing increased optical absorbance. The synthesized films were used in the photocatalytic degradation of methylene blue showing an increase in photocatalytic degradation when only TiO2 is used. The introduction of silver with TiO2 inhibited the effective photocatalytic degradation of methylene blue. PMID:24593655

  14. Cost-Effective TiAl based Materials

    NASA Technical Reports Server (NTRS)

    Moxson, V. S.; Sun, Fusheng; Draper, Susan L.; Froes, F. H.; Duz, V.

    2003-01-01

    Because of their inherent low ductility, TiAl-based materials are difficult to fabricate, especially thin gage titanium gamma aluminide (TiAl) sheet and foil. In this paper, an innovative powder metallurgy approach for producing cost-effective thin gage TiAl sheets (with 356 mm long and 235 mm wide, and a thickness of 0.74, 1.09, 1.55, and 2.34 mm, respectively) is presented. The microstructures and tensile properties at room and elevated temperatures of the thin gage TiAl are studied. Results show that these TiAl sheets have a relatively homogenous chemistry, uniform microstructure, and acceptable mechanical properties. This work demonstrates a cost-effective method for producing both flat products (sheet/foil) and complex chunky parts of TiAl for various advanced applications including aerospace and automotive industries.

  15. Superelastic properties of biomedical (Ti-Zr)-Mo-Sn alloys.

    PubMed

    Ijaz, Muhammad Farzik; Kim, Hee Young; Hosoda, Hideki; Miyazaki, Shuichi

    2015-03-01

    A new class of Ti-50Zr base biomedical superelastic alloys was developed in this study. The (Ti-Zr)-Mo-Sn alloys exhibited a shape memory effect and superelastic property by adjusting Mo and Sn contents. The (Ti-Zr)-1.5Mo-3Sn alloy revealed the most stable superelasticity among (Ti-Zr)-(1-2)Mo-(2-4)Sn alloys. The superelastic recovery strain showed a strong dependence on heat treatment temperature after cold working in the (Ti-Zr)-1.5Mo-3Sn alloy. The superelastic recovery strain increased as the heat treatment temperature increased although the critical stress for slip decreased. The (Ti-Zr)-1.5Mo-3Sn alloy heat treated at 1073K exhibited excellent superelastic properties with a large recovery strain as large as 7% which is due to the strong {001}β<110>β recrystallization texture. PMID:25579891

  16. Localized TiSi and TiN phases in Si/Ti/Al/Cu Ohmic contacts to AlGaN/GaN heterostructures

    NASA Astrophysics Data System (ADS)

    Yoon, Seonno; Song, Yunwon; Lee, Seung Min; Lee, Hi-Deok; Oh, Jungwoo

    2016-05-01

    Microstructural changes in Si/Ti/Al/Cu (10/40/60/50 nm) Ohmic contacts to AlGaN/GaN heterostructure were investigated for complementary metal-oxide semiconductor compatible processes. Si/Ti/Al/Cu metallization exhibited a low specific contact resistance of 3.6 × 10-6 Ω-cm2 and contact resistance of 0.46 Ω-mm when a Si interfacial layer was used. Without a designated barrier metal, TiSix alloys that formed in the metallic region effectively suppressed Cu diffusion. The shallow TiN junction in AlGaN/GaN was attributed to TiSix in the metallic regions. Microstructural changes were detected by systematic physical characterization.

  17. Effects of water absorption of dielectric underlayers on Al-Si-Cu film properties and electromigration performance in Al-Si-Cu/Ti/TiN/Ti interconnects

    NASA Astrophysics Data System (ADS)

    Yoshida, Tomoyuki; Hashimoto, Shoji; Ohwaki, Takeshi; Mitsushima, Yasuichi; Taga, Yasunori

    1998-01-01

    The effects of underlying dielectric (phosphosilicate glass and borophosphosilicate glass) films to a humid air ambient on Al-Si-Cu film properties and electromigration (EM) performance in Al-Si-Cu/Ti/TiN/Ti layered films have been investigated as a function of the boron content and exposure time of the dielectric films. The Al(111) orientation in the layered films was found to improve drastically with increasing boron content and exposure time. The full width at half maximum value of an Al(111) x-ray rocking curve reached less than 1°. It was also found that the Al-Si-Cu surface becomes smoother and grain sizes increase as the Al(111) orientation improves. The improved Al(111) orientation was attributed to the improved Ti(002) orientation of the bottom Ti films. Further, it was demonstrate that interconnects fabricated from the improved layered film have excellent EM performance.

  18. A Review Corrosion of TI Grade 7 and Other TI Alloys in Nuclear Waste Repository Environments

    SciTech Connect

    F. Hua; K. Mon; P. Pasupathi; G. Gordon

    2004-05-11

    Titanium alloy degradation modes are reviewed in relation to their performance in repository environments. General corrosion, localized corrosion, stress corrosion cracking, hydrogen induced cracking, microbially influenced corrosion, and radiation-assisted corrosion of Ti alloys are considered. With respect to the Ti Grade 7 drip shields selected for emplacement in the repository at Yucca Mountain, general corrosion, hydrogen induced cracking, and radiation-assisted corrosion will not lead to failure within the 10,000 year regulatory period; stress corrosion cracking (in the absence of disruptive events) is of no consequence to barrier performance; and localized corrosion and microbially influenced corrosion are not expected to occur. To facilitate the discussion, Ti Grades 2, 5, 7, 9, 11, 12, 16, 17, 18, and 24 are included in this review.

  19. Microstructure and properties of simultaneously processed Nb-Ti and Nb-Ti-Ta superconducting wires

    SciTech Connect

    Taillard, R.; Florianova, E.; Bruzek, C.E.

    1997-06-01

    The evolution of the microstructure (sub-band size, {alpha} phase precipitation) of a Nb- 47.1wt%Ti and of a Nb-45 wt%Ti-15wt%Ta alloys is followed during their simultaneous thermomechanical processing. The effects of a Ta addition, cold work prestrain, and of the temperature and duration of heat treatments on the volume fraction, size, density and localization of the particles of {alpha} phase are especially documented. Widmanstatten {alpha} strengthens the NbTiTa alloy and exerts a deleterious influence on J{sub c}. Some solutions are proposed to these harmful effects. At last, the relationships describing the dependence of the {alpha} phase distribution on strain are also considered.

  20. Spray forming of NiTi and NiTiPd shape-memory alloys

    NASA Astrophysics Data System (ADS)

    Smith, Ronald; Mabe, James; Ruggeri, Robert; Noebe, Ronald

    2008-03-01

    In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

  1. Directional solidification of (Ti, Zr) carbide-(Ti, Zr) diboride eutectics

    SciTech Connect

    Sorrell, C.C.; Beratan, H.R.; Bradt, R.C.; Stubican, V.C.

    1984-03-01

    The ZrC-ZrB2, ZrC-TiB2, and TiC-TiB2 metal diboride-metal carbide pseudo-binary eutectic systems have been successfully solidified directionally by means of the floating zone method. The first and third of these eutectics possess a morphology consisting of columnar grains of parallel lamellae with interlamellar spacings that adhere to the lambda-squared (R) C relationship, while the second is noted to solidify in a Chinese calligraphy-like morphology of broken and deformed lamellae. This phenomenon may be related to solid solution effects, but it did not prevent the interlamellar spacings from following the aforementioned law. The calligraphic effect's values are larger than those of the other two systems, and the constant, C, is accordingly about an order of magnitude larger. All three of these cubic-hexagonal systems exhibited identical epitaxial relationships. 24 references.

  2. Anodic mesoporous TiO2 layer on Ti for enhanced formation of biomimetic hydroxyapatite.

    PubMed

    Dey, Tuli; Roy, Poulomi; Fabry, Ben; Schmuki, Patrik

    2011-04-01

    Ti surfaces can be very efficiently coated by a robust (μm thick) mesoporous titania layer (MTL). These coatings are produced by anodization of Ti at elevated temperature in a glycerol/K(2)HPO(4) electrolyte, followed by an appropriate etching process. In the present work we examine these layers with regard to their ability to form hydroxyapatite. Immersion tests in two types of simulated body fluids (Kokubo SBF and Bohner and Lemaitre SBF) combined with scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy investigations show that these MTL layers lead to a significant enhancement of HAp formation and anchoring in the structure compared with non-coated or even nanotubular Ti surface coatings (these were recently reported to be the most efficient in terms of HAp formation). PMID:21075221

  3. Spray Forming of NiTi and NiTiPd Shape-Memory Alloys

    NASA Technical Reports Server (NTRS)

    Mabe, James; Ruggeri, Robert; Noebe, Ronald

    2008-01-01

    In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

  4. Distribution of Pd clusters on ultrathin, epitaxial TiOx films on Pt3Ti(111)

    PubMed Central

    Breinlich, Christian; Buchholz, Maria; Pertram, Tobias; Becker, Conrad; Wandelt, Klaus

    2015-01-01

    Summary Scanning tunnelling microscopy (STM) was used to investigate the nucleation and growth of palladium clusters on two different, ultrathin, epitaxial, titania films grown on a Pt3Ti(111) surface. The first oxide phase, z'-TiOx, is anisotropic and consists of parallel stripes separated by trenches. Defects (i.e., oxygen vacancies) in this structure are confined to these trenches and act as nucleation sites. Therefore, the Pd clusters are mostly arranged in unidirectional rows along the trenches, creating a template effect. The second phase, w'-TiOx, exhibits a hexagonal, long range, (7 × 7)R21.8°, Moiré-type superstructure with fewer and shallower defects, making the template effect less discernible. PMID:26665071

  5. Effects of TiCl4 Purity on the Sinterability of Armstrong-Processed Ti Powder

    SciTech Connect

    Weil, K. Scott; Hovanski, Yuri; Lavender, Curt A.

    2009-04-03

    A series of high purity and low purity powders were synthesized from TiCl4 by the Armstrong process. While both powders displayed swelling when consolidated and sintered, the lower purity powder exhibited this phenomenon in significantly lower degree. The improvement is attributed to the increase in the onset of sintering temperature, which mitigates the entrapment of volatile impurities that would otherwise lead to pore formation and growth. The net effect is that the use of a lower purity TiCl4 may beneficial in two ways: (1) it is a potentially lower cost precursor to Ti powder production and (2) the trace impurities allow higher density components to be fabricated via a typical low-cost press and sinter approach.

  6. (29)Si, (47)Ti, (49)Ti and (195)Pt solid state MAS NMR spectroscopic investigations of ternary silicides TPtSi, germanides TPtGe (T = Ti, Zr, Hf) and stannide TiPtSn.

    PubMed

    Benndorf, Christopher; Eckert, Hellmut; Pöttgen, Rainer

    2016-05-10

    Eight ternary tetrelides TPtX (T = Ti, Zr, Hf; X = Si, Ge, Sn) were synthesized from the elements by arc-melting and subsequent annealing. TiPtSi, ZrPtSi, ZrPtGe, HfPtSi and HfPtGe crystallize with the orthorhombic TiNiSi type structure, in the space group Pnma. The structures of HfPtSi (a = 654.44(9), b = 387.97(6), c = 750.0(1) pm, wR2 = 0.0592, 411 F(2) values, 20 variables) and HfPtGe (a = 660.36(7), b = 395.18(4), c = 763.05(8) pm, wR2 = 0.0495, 430 F(2) values, 20 variables) were refined from single crystal X-ray diffractometer data. TiPtSn adopts the cubic MgAgAs type. TiPtGe is dimorphic with a TiNiSi type high-temperature modification which transforms to cubic LT-TiPtGe (MgAgAs type). All phases were investigated by high resolution (29)Si, (47)Ti, (49)Ti and (195)Pt solid state MAS NMR spectroscopy. In the cubic compounds, the (47/49)Ti NMR signals are easily detected owing to the absence of quadrupolar broadening effects. The (195)Pt resonances of the orthorhombic compounds are characterized by strongly negative isotropic Knight shifts and large Knight shift anisotropies, whereas positive isotropic Knight shifts and no anisotropies are observed for the cubic compounds. These results indicate that the phase transition in TiPtGe is associated with dramatic changes in the electronic properties. Within each group of isotypic compounds the isotropic (29)Si, (47/49)Ti and (195)Pt Knight shifts show systematic dependences on the transition metal or tetrel atomic number, suggesting that the numerical values are influenced by the electronegativities of the metallic (or metalloid) neighbours. PMID:27097719

  7. The great big alveolar TI cell: evolving concepts and paradigms.

    PubMed

    Dobbs, Leland G; Johnson, Meshell D; Vanderbilt, Jeff; Allen, Lennell; Gonzalez, Robert

    2010-01-01

    Pulmonary alveolar type I cells (TI cell) are very large (approximately 5400 microm(2) in surface area) squamous cells that cover more than 98% of the internal surface area of rodent lungs. In the past, TI cells were believed to serve only passive barrier functions, with no active functional properties in the lung. The fairly recent development of methods to isolate TI cells has permitted investigation of functions of this cell type for the first time. Resolvable by electron microscopy, TI cells contain microvilli and organelles typically associated with metabolic functions, such as mitochondria, abundant smooth and rough endoplasmic reticulum and Golgi apparatus. TI cells contain the molecular machinery necessary for ion transport and take up Na(+), K(+), and Cl(-), from which one can infer that it is likely that they play a role in ion and fluid transport in vivo. Because the abundance/microm(2) of highly selective Na(+) channels (HSC channels, consisting of all three ENaC subunits) is the same in TI and TII cells and because TI cells cover the majority of the lung internal surface, TI cells may play the major role in bulk transport of Na(+). In vitro, TI cells can proliferate and exhibit phenotypic plasticity, raising the question of whether this cell type may play a role in development and lung repair after injury. From gene expression analysis of TI cells, one can infer a variety of other possible functions for TI cells. The development of techniques to administer transgenes specifically to TI cells will permit direct study of this cell type in vivo. PMID:20054144

  8. Creep deformation of a two-phase TiAl/Ti[sub 3]Al lamellar alloy and the individual TiAl and Ti[sub 3]Al constituent phases

    SciTech Connect

    Bartholomeusz, M.F.; Wert, J.A. ); Qibin Yang )

    1993-08-01

    Two-phase TiAl/Ti[sub 3]Al alloys in which the constituent phases form a lamellar microstructure are reported to possess good combinations of low-temperature fracture toughness, tensile strength and fatigue resistance. However, information about the high-temperature creep properties of the two-phase TiAl/Ti[sub 3]Al alloys with lamellar microstructures (referred to as lamellar alloys in the remainder of the paper) is limited. Based on a simple rule of mixtures model of strength, it would be expected that the creep rates of the lamellar alloy would be between the creep rates of TiAl and Ti[sub 3]Al. In contrast to composite model predictions of strength, Polvani and coworkers found that the minimum creep rates of two duplex alloys, a [gamma]/[gamma][prime] nickel-base superalloy and NiAl/Ni[sub 2]AlTi, were significantly lower than the minimum creep rates of either of the constituent phases. They also reported that most dislocations in the two-phase NiAl/Ni[sub 2]AlTi alloy were contained within the semi-coherent interfacial dislocation networks between the two phases. Based on this observation they proposed that the creep rate is controlled by the rate at which dislocations moving through both phases are emitted and absorbed by the interphase dislocation networks. The greater strain hardening rate of the lamellar TiAl/Ti[sub 3]Al alloy suggests that it may exhibit lower steady-state creep rates that the individual constituent phases. The objective of the present study is to evaluate the creep properties of a TiAl/ Ti[sub 3]Al lamellar alloy and of the individual constituent phases. In this paper, the results of this investigation will be presented and compared with previously published results for this alloy system.

  9. Electrical resistivity of V-Cr-Ti alloys

    SciTech Connect

    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.

  10. Molar Volume Modeling of Ti-Al-Nb and Ti-Al-Mo Ternary Systems

    NASA Astrophysics Data System (ADS)

    Zhu, Jun; Zhang, Chuan; Cao, Weisheng; Chen, Shuanglin; Zhang, Fan; Park, Joon Sik; Yi, Seonghoon

    2015-08-01

    Molar volume modeling was performed for both Ti-Al-Nb and Ti-Al-Mo ternary systems based on the thermodynamic modeling of these two systems. Comparison between the calculated phase equilibria and the experimental data proved the accuracy of thermodynamic modeling. With the calculated density contour curves superimposed on the equilibrium phase diagram, it provides a map for alloy developers to identify the promising alloy compositions that satisfy both the phase stability and density requirements and rule out those that fail to meet the requirements.