Papers by Keyword: Ti

Abstract: Heat sink materials not only should have higher thermal conductivity, but also have smaller difference of thermal expansion with cooled material. diamond/copper composites were made by the powder metallurgy method. Vacuum slowly vapor deposition technique was employed to deposit a titanium film on diamond particles before mixing with Cu powder in order to improve the bonding strength between Cu and diamond particles during sintering. The thermal expansion of diamond/Cu d composite was measured in the temperature range from 50 to 600 °C. The results show that the titanium film on diamond improves the interfacial bonding and reduces the coefficient of thermal expansion (CTE) of Cu/diamond composites. The CTE of diamond/Cu composites decreases with increasing diamond volume fraction as the results of mixture rule and the intense restriction effect of diamond reinforcement on the copper matrix. The residual stresses and pores in the composites affect instantaneous thermal expansion of diamond/Cu composites.

Abstract: According to the working condition of the wear-resistant and heat-resistant parts, it designed the composition of the wear-resistant and heat-resistant steel. Different amount of Ti were added to wear-resistant and heat-resistant steel. The effects of Ti on microstructure, hardness and wear resistance of wear-resistant and heat-resistant steel were researched by microstructure observation, x-ray diffraction，hardness and wear resistance test. The results show that proper amount Ti combines with C to form a certain number particle TiC in the wear-resistant and heat-resistant steel. TiC is dispersively distributed in austenite matrix and improves the hardness and wear resistance of wear-resistant and heat-resistant steel greatly. It has a certain economic benefit.

Abstract: In order to refine the microstructure of A356 alloy, the effect of different contents of Ti on A356 alloy was analyzed with scanning electron microscopy (SEM). Experimental results show that it is not following the law of the more the content of Ti is, the finer the microstructure in the range of 0% to 7.5% Ti. However, the microstructure undergoes a first refining as the content of Ti is less than 0.3% and then coarsening with the increasing of Ti. Further, the mechanism of grain refiner is explained from three aspects. Finally, the hardness of A356 alloy is studied to verify the effect of different contents of Ti. The results confirm that the variety of hardness is in accordance with that of microstructure.

Abstract: Hydroxyapatite (HAP) coatings are widely used to improve the biocompatibility of the substrate. In this paper, Ti-based HAP coatings were prepared by RF magnetron sputtering method, and the coatings’ structure and composition were analyzed by SEM，EDX and IR spectroscopy. When the sputtering conditions were 290 W and 120-180 min, the nano-HAP surface coatings had formed on the surface of Ti-based. The average size of grain was 48nm, and the elemental composition of the coatings was consistent with the HAP coatings. The coating thickness was 513±15~985±25 nm, Ca/P=1.51±0.03~1.84±0.04. After 90 days following the day when Ti-based HAP materials were implanted, bone tissues had covered the surface of the coatings, osteoclasts could be seen, and the bond strength of the coatings had not changed significantly. HAP coatings prepared by the method of RF magnetron sputtering have excellent bioactivity and stability.

Abstract: Crystallinity of 4H-SiC bulk crystal obtained by solution growth technique was characterized mainly by KOH etching of the off-ground and serially ground specimen. Marked reduction of basal plane dislocation, threading edge and screw dislocations during the growth of on-axis crystal was confirmed. Cross-sectional TEM observation revealed the rapid reduction behavior of threading dislocations microscopically. AFM observation of as-grown morphology showed that screw dislocation dipoles is related to the reduction of threading screw dislocations and single domain formation, which is essential for establishing the high crystallinity.

Abstract: _{Subscript text}In this text, Ti/TiO₂-SnO₂ composite electrodes were prepared by Sol-Gel method. Rare earth-doped method can improve the catalytic performance of the composite electrodes. Based on the degradation of oil-field wastewater, e of the electrode surface and the element composition of surface layers were analyzed by SEM, EDX and XRD. When the current density was 30mA/cm², electrode submersed area was 2cm², pH was 3~5, temperature was 30°C and the electrolysis time was 60min, the best treatment process was obtained. The average removal rate of oil content and CODcr were 92.8% and 89.2%, respectively. Under the best treatment process the contaminant was degradated to other intermediate substances during degradation, finally mineralized to CO₂ and H2O.

Abstract: In this paper, the effect of different Ti content on the brazed joint microstructures was studied, including the reaction zone states, microstructures of the reaction interface on both ceramic and Invar alloy side. The added Ti content was 2%, 3%, 5%, 6% and 10%. The results showed that Ti had great effect on the thickness of reaction layer on the invar alloy side. Ti can inhibit the growth of the diffusion layer.

Abstract: High rate film deposition via Gas Flow Sputtering was used to develop both metallic titanium films and ceramic titania coatings for implants. The structure formation of the coatings can be described by a modified model of structure zones according to Thornton. The potential of Gas Flow Sputtering for designing implant surfaces with controlled morphology and roughness is demonstrated.

Abstract: Hydroxyapatite (HAP) is known as a kind of bioactive and biocompatible material, HAP coatings are used to improve the biocompatibility of substrate by some researchers. In this paper, homogenous precipitation of hydroxyapatite was formed in the system of CaNa₂EDTA -(NH₄)₂HPO₄-NH₄OH-H₂O, and HAP powder was obtained after calcinations at 800 and grinding. Add HAP in UHMWPE o-xylene solution to get dipping solution and prepare HAP/UHMWPE-coated titanium by dipping coating process. Scratch test demonstrated that Ti-HAP/UHMWPE material started to shine metallic luster under 1.03 N, and adhesive strength is 32MPa. UHMWPE not only simplified the process of preparing HAP-coated material, but also enhanced the adhesive strength, which shows great potential in biomedical areas.

Abstract: The lattice constants, total energies and densities of states of Ti, Zr and Hf in ⅣB group with different crystalline structures have been calculated, and the results have been compared with the results of the projector augmented wave (PAW) method in first-principles, CALPHAD and experiments. It is found that the results of lattice stability in this paper agree completely with those of the PAW method in first-principles and agree well with those of CALPHAD. Further analyses of lattice stability from electronic structures show that the crystalline Ti,Zr and Hf with hcp structures have the obvious character of stable phases, but fcc and bcc structures have the character of metastable and unstable phases, agreeing with the results of total energy calculations. It is found from the analyses of atomic populations that the transiton numbers of electrons from the s state to the p and d states for the hcp, fcc and bcc crystals decrease with the increase in elemental period, and the transiton number of electrons from the s state to the p state decrease dramatically, but the transiton from the s state to the d state increase dramatically, leading to much more number of electrons in the d state than that in the s or p state, stronger cohesion or higher cohesive energy between atoms in heavy metals and accordingly the stabler lattice in these heavier metals.