Papers by Keyword: Ti

Abstract: Using the hot-pressing sintering method, Cu-matrix bonding diamond tool bits including 0, 4 and 8 % Ti content (wt.%) were prepared. The effect of Ti content on the mechanical properties of Cu-matrix bonding diamond tool bits was studied. The experimental results showed that the influence of Ti content on the flexural strengths of Cu-matrix bonding bits and diamond tool bits are significant. Furthermore, the morphologies and compositions of fracture surfaces of diamond tool bits were characterized by scanning electron microscope and energy dispersive spectroscopy. The results illustrated that when the Ti content was 4%, the interface bonding between the diamond and the Cu-matrix bonding was the strongest, the flexural strength had the maximum values of the Cu-matrix bonding bits and the diamond tool bits, the values were 644 MPa and 515.8 MPa respectively.

Abstract: Amorphous Fe₇₅Si_20-xB₅M_x powders with M= Ti, Ta or Zr and x = 0 and 5 were synthesized by wet mechanical alloying, using benzene as a surfactant. The thermal stability of the Fe-Si-B alloy increases by introducing transition metals. The replacement of 5% Si with Ti, Ta or Zr leads to an increase of the crystallization temperature. It was found that the replacement of 5% Si with Zr increases the crystallization temperature with 115 °C, and also reveals a glass transition temperature around 580 °C.

Abstract: Solidification behaviors of IC10 alloy with different titanium content were investigated by isothermal solidification method. Volume percentage of liquid and precipitation temperature of primary MC type carbide, eutectic and secondary γ′ phase were investigated. The results showed that with the increase of Ti content in the alloy, the liquidus, solidus and MC carbide formation temperatures decreased, on the contrary, the formation of γ+γ′ eutectic and secondary γ′ increased. For the IC10 alloy with 1.5% titanium content, it is earlier for the interdendritic pools to be divided into the parts. At this condition, melted portion of the alloy resided during isothermal process. As a result, the castability of the IC10 with 1.5% titanium is thus the lowest.

Abstract: The elbow total implant is in appearance a simple orthopedic device, with few components and no complex mechanisms. In spite of the reported successful surgical interventions, there are still many medical reports which show that a certain percentage of the implants fails.In our work we conceptually approach a computer assisted design of a Coonrad-Morrey like total elbow implant and simulate the mechanical behavior by finite element analysis, for three different loads (10 N, 50 N, and 100 N). Materials used for simulation were Ti, TiNi and Ti6Al4V for the metallic components, and UHMWPE for bushing polymeric components. Through our results we confirmed the practical observations, namely that the hinge mechanism is an important region where the failures initiates from, as the highest stress is concentrated on the polymeric components.

Abstract: Diffusion bonding was used to join silicon carbide (SiC) to SiC substrates using three kinds of interlayers: physical-vapor-deposited (PVD) Ti coatings (10 and 20 μm) on the substrate, Ti foils (10 and 20 μm), and a Mo–B foil (25 μm). Two types of substrates were used: chemical-vapor-deposited SiC and SiC fiber bonded ceramic (SA-TyrannohexTM), the latter having a microstructure consisting of SiC fibers and a carbon layer. The microstructures of the phases formed during diffusion bonding were investigated using transmission electron microscopy (TEM) and selected-area diffraction analysis. TEM samples were prepared using a focused ion beam, which allowed samples to be taken from the reacted area. The effect of the interlayer material and the direction of the SiC fibers in the substrate with respect to the interlayer was evaluated. Scanning electron microscopy and TEM revealed good diffusion bonds in all samples; however, some samples exhibited small amounts of microcracking. The diffusion bonded CVD SiC sample using the 10-μm-thick PVD-Ti interlayer formed more of the stable phase and less of the intermediate phases than the sample using the Ti foil. This behavior was caused by the presence of columnar Ti grains in the interlayer, which may have enhanced the migration of Si and C atoms in the interlayer. In the SA-Tyrannohex samples using the Ti-foil interlayer, the chemical reaction proceeded more rapidly when the fibers were parallel to the interlayer than when they were perpendicular. This behavior was likely caused by the hexagonal carbon layer always facing the Ti interlayer in the sample with perpendicular fibers; this peculiar microstructure reduced the mobility of Si and C migrating into the interlayer. The SA-Tyrannohex sample using the Mo–B foil as the interlayer had excellent diffusion bonds with no microcracks or voids. In this system, Mo₅Si₃C, Mo₂C, and Mo₅Si₃ formed. While phases have anisotropic coefficient of thermal expansion (CTE), the CTE mismatch between those phases and the substrate was apparently smaller than the mismatch in the samples using Ti interlayers.

Abstract: Gradient-porous Titanium alloys can be applied to manufacturing implants for bone replacement, due to their good biological and mechanical compatibility. In this work, the feasibility of fabricating gradient-porous Titanium by centrifugal deposition and vacuum sintering was investigated. The apparent porosity of the gradient-porous Ti examined by Archimedes method is 56%. And the open pores occupy 89%. The pore structure was observed by an optical microscope. And its porosities at different radius were calculated by image software based on optical microscopic images. In addition, a nanoindentation was employed to characterize the mechanical properties at different radius. The results showed that the porosity of the sample increased with increasing of radius. Besides, both the elastic modulus and hardness changed alone radius with a same trend.

Abstract: Due to the electrical and physical analyses, the robust negative voltage unipolar resistive switching behaviors in Ti/ZrO₂/Ti/ZrO₂/Pt device have been investigated. The Ti diffusion in ZrO₂ film can generate more amounts of oxygen vacancies in it, which leads the lower value and narrower variation in forming voltage. Moreover, the good performances with more than 1000 switching cycles and long retention test can be achieved in the present device.

Abstract: Cu-15Ni-10Mn alloy as-cast, which smelted at atmosphere, has a typical dendrite structure in Ni segregation characteristics. The content of Ni is higher on dendrite arms spacing than on the dendrite arms, but the content of Mn is less than on the trunk. Due to the Mn oxides easily, the processing performance of alloy as-cast cant meet the requirement of metalworking. The gas content of ingots can be reduced by adding a small amount of zinc during smelting, and the metalworking features can be improved by adding trace Ti that will refine the arms of alloy. The research results show that the grains of Cu-15Ni-10Mn alloy as-cast can be refined by tiny amount of Ti. The grain size decreases with the increase of the content of Ti, the branches size of alloy adding 0.2% Ti is about 30μm that is only 49.4% the size of the alloy without Ti. Titanium, copper and Nickel can form compounds of CuNi2Ti. The hardness peak of alloy with 0.2%Co is 114Hv that is 8% higher than the alloy without Ti. The electrical conductivity of Cu-15Ni-10Mn alloy as-cast waves not clearly.

Abstract: Al-12Si-3.2Cu-1Mg-2.4Ni-χTi (χ=0, 0.2) alloys were prepared by squeeze casting process, and then heat-treated. The mechanical properties were tested at 350°C, the microstructure and phases in them were investigated by optical microscope, SEM, EDS and XRD. It is found that the grain size has an obvious increment after 0.2 wt. % Ti additions to Al-12Si-3.2Cu-1Mg-2.4Ni, and the ultimate tensile strength at elevated-temperature increased accordingly. Intermetallic compounds, such as γ-Al₇Cu₄Ni, M-Mg₂Si, Q-Al₅Cu₂Mg₈Si₆ and δ-Al₃CuNi existing in alloys with and without Ti addition. Needle-like Ti containing phase with the elements of Al, Si and Ti created in Al-12Si-3.2Cu-1Mg-2.4Ni-0.2Ti alloy, and the eutectic Si is found to distribute by the side of Ti containing phase.

Abstract: An ultra- thin Ti film with a thickness of less than 30 nm was deposited on the surface of a silicon wafer by the filtered arc deposition system. A novel technique was adopted to create a height step between the coated area and non-coated area (silicon wafer) during deposition. The surface morphology and thickness of the film was detected by atomic force microscopy (AFM). The AFM results showed that the deposited film formed a smooth structure on the silicon wafer and the height step between the coating and silicon wafer was clear enough to give the thickness of the deposited film. The composition of the deposited film was detected by a combined use of Ellipsometry and AFM. Natural oxidisation of Ti (TiO2) was found on the top of the Ti film after deposition, and the thickness of TiO2 was determined by ellipsometry to be about 0.6 nm.