Papers by Keyword: Titanium Alloy

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Authors: Agnieszka Szkliniarz, Wojciech Szkliniarz
Abstract: In this work, the possibility of melting titanium alloys in vacuum induction furnaces in metal and ceramic crucibles and in ceramic crucibles with coatings deposited by the plasma-spray method or by hand using a brush was evaluated. The effect of the crucible material and the coating material on the chemical composition, microstructure and alloy properties was studied. The main criterion for evaluating the suitability of individual crucibles was the content of oxygen in the molten alloys and of impurities remaining as a result of the reaction of the liquid alloy with the crucible and coating material.
139
Authors: Min Wang
Abstract: For ring rolling without axial rolls, how to effectively suppress axial spread has become an important subject. In the paper, a reliable coupled thermo-mechanical three-dimensional (3D) finite element (FE) model for hot rolling of large rings is developed. Spread evolution of titanium alloy large rings with different sizes are explored and compared based the developed model. The main results show that (1) the spread in a ring takes on an axisymmetric distribution after the first revolution of the ring. (2) with the equivalent ratio of feed amount per revolution decreasing, the peak spread transfers from the outer layer to the inner layer for rings with different sizes.
2092
Authors: Yi Rong Zhang, Hou Jun Qi
Abstract: A common mechanical model of ball-end milling cutter is analyzed in this paper, and take advantage of the orthogonal experiment method to make experiment of milling to identify the milling force coefficients with the titanium alloy material as the test object.Then put the coefficients in the mechanical model of ball to use MATLAB software to predict the milling force. The results of experiment and results of simulation are basically identical, it shows that the mechanics model of ball milling is proved to be correct.
1231
Authors: Xiao Hua Zhang, Ding Gen Xiang, Dao Xin Liu
Abstract: Ion-beam-assisted deposition (IBAD) was investigated as a potential way to increase the fretting fatigue resistance of Ti-8Al-1Mo-1V alloy at elevated temperature. Three coating systems, hard TiN film with good toughness and soft Al film of low friction and Cu/Ni multilayer films with modulation period thickness of 20~600nm have been applied on the base material. Coefficients of friction and fretting fatigue lives of the specimens with and without film were compared. The film damage was characterized through scanning electron microscopy. The results indicate that the IBAD technique can prepare all films with high bonding strength and excellent lubricating properties. The fretting fatigue life of the Ti-8Al-1Mo-1V alloy with the TiN film was improved by a factor of 2.4 as compared to the uncoated substrate at elevated temperature because of the excellent wear and fatigue resistance and good toughness of the film. Excellent wear resistance and good anti-fatigue properties could be simultaneously obtained by a single hard film to control the fretting fatigue damage. The IBAD Al film significantly improved the fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy at elevated temperature for good lubricating property. The fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy was improved by all the Cu/Ni multilayer films. However, the fretting fatigue resistance did not increase monotonically with the modulation period of the films. Films with a modulation period of 200 nm had the highest fretting fatigue resistance among the multilayer films prepared owing to their high toughness and strength and good lubricating and anti-fatigue action. The fretting fatigue resistance of films with a modulation period of 20 nm was low because of the poor fracture toughness and crack propagation resistance, even though these films had the highest hardness and good fretting wear resistance. Thus, comprehensive properties, including high toughness and strength, must be considered for multilayer films used to improve the fretting fatigue resistance of titanium alloys.
346
Authors: Wei Tian, Xiao Hua Zhang
Abstract: Ion-beam-assisted deposition (IBAD) was investigated as a potential way to increase the fretting fatigue resistance of Ti-8Al-1Mo-1V alloy at elevated temperature. Three coating systems, hard TiN film, Al film and Cu/Ni multilayer films have been applied on the base material. Coefficients of friction and fretting fatigue lives of the specimens with and without film were compared. The results indicate that the IBAD technique can prepare all films with high bonding strength and excellent lubricating properties. The fretting fatigue life of the Ti-8Al-1Mo-1V alloy with the TiN film was improved by a factor of 2.4 as compared to the uncoated substrate at elevated temperature because of the excellent wear and fatigue resistance and good toughness of the film. The IBAD Al film significantly improved the fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy at elevated temperature for good lubricating property. The fretting fatigue resistance of the Ti-8Al-1Mo-1V alloy was improved by all the Cu/Ni multilayer films. However, the fretting fatigue resistance did not increase monotonically with the modulation period of the films.
7
Authors: Kengo Narita, Mitsuo Niinomi, Masaaki Nakai, Toshikazu Akahori, Harumi Tsutsumi, Kazuya Oribe
Abstract: Implanting a spinal fixture using metallic rods is one of the effective treatments for spinal diseases. Because cyclic bending stress is loaded on the implant rods when patients move their upper bodies in daily life, bending fatigue properties are important for the implant rod. Further, the implant rods are bended plastically into a curved shape of spine by hand in a surgical operation. In that case, keeping shape is important, namely bending spring back properties are important factors. On the other hand, a biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (mass %) alloy (TNTZ), has been developed by the authors. Currently, this alloy are investigated to be applied to the above mentioned implant rod practically. Therefore, four-point bending fatigue and three point-bending spring back properties of TNTZ subjected various heat treatments were examined in this study. TNTZ rods were subjected to solution treatment, and then some of them were subjected to aging treatment at 673 K or 723 K for 259.2 ks, followed by water quenching. Then, four-point bending fatigue and three-point bending spring back tests were carried out on TNTZ rods subjected to the various heat treatments mentioned above. The bending fatigue strength at 2.5 million cycles in the high cycle fatigue region are not much different among any TNTZ rod. However, the bending fatigue strength of the Ti-6Al-4V ELI (Ti64) rod exceeds the fatigue strengths of every TNTZ rods in both low and high cycle fatigue regions. On the other hand, the lower spring back, which is a favorable property, was obtained for some TNTZ rod than Ti64 rod.
400
Authors: Fan Sun, Thierry Gloriant, Philippe Vermaut, Pascal Jacques, Frédéric Prima
Abstract: The increased use of metallic biomaterials in contact with blood e.g. for application as coronary stents is steadily resulting in the development of new biomaterials. Conventional bare-metal stents made by stainless steel were reported on adverse reactions against human body and are gradually replaced by coated stainless steel. The new generation of stent requires fundamental improvements at the materials point of view. Although titanium and classical Ti-alloys display superior biocompatibility compared to other metallic materials (stainless steels, Co-Cr), the major drawback of their relatively low ductility (typically 15%-25% of elongation) seriously limits their applications as cardiovascular stents, where large ductility is basically required during the stent deployment procedure and long-term service. In this paper, new titanium alloys with high ductility, a binary Ti-12Mo (wt%) and a ternary Ti-9Mo-6W (wt%) were designed by using a chemical formulation strategy based on the electronic design method called “the d-electron alloy design method”. Both alloys were synthesized and thermo-mechanically treated into beta-metastable state. In tensile tests, both alloys exhibited outstanding ductility of 43% and 46% in total elongation at room temperature, which is almost two times greater than the normal value shown with classical titanium alloys. Optical microscopy and detailed TEM observations on the deformed specimens revealed a complex deformation mechanism, involving {332}<113> mechanical twinning, stress induced plate shaped omega phase and stress induced martensitic (SIM) transformation β-α’’.
129
Authors: Dong Zhang, Bao Ping Zhang, Zhi Ge Li, Lin Wang, Bin Liu, Jin Qing Wang
Abstract: This study is to evaluate the biocompatibility of HAP/Ti gradient coating by microarc oxidation and biomimetic process. Titanium alloys were activated by microarc oxidation (MAO), and immersed in simulated body fluid to prepare HAP/Ti gradient coating. Scanning electron microscopy (SEM) had been used to investigate the microstructure of the coatings. The biocompatibility of the coatings was evaluated by animal acute and subacute toxicity test, micronucleus test, hemolysis test, and oral mucosa test. The results showed HAP/Ti gradient coating was successfully fabricated on the substrate. The animal experiment showed the coating had not short-term toxicity, oral mucosa irritation, and micronucleus occurrence rate was 3.2 ‰ and hemolysis rate was 2.5%. The HAP/Ti gradient coating made by MAO and biomimetic process showed good bio-security and compatibility, it may be new oral implant materials.
325
Authors: Kun Mediaswanti, Cui E Wen, Elena P. Ivanova, Francois Malherbe, Christopher C. Berndt, Vy Thi Hong Pham, James Wang
Abstract: Titanium and titanium alloys have been extensively studied for many applications in the area of bone tissue engineering. However, dense titanium is prone to lead into aseptic loosening due to their high elastic modulus compared to natural bone. One way to lower the elastic modulus is to produce a porous structure of the metallic alloy by adjusting its porosity. Another concern is the bioinertness of titanium that have no direct chemical bonding with surrounding tissue. One approach to improve the healing process is the application of a calcium phosphate coating onto the surface of biomedical devices and implants. Biomimetic creation of surface using alkali heat treatment with silica addition was employed in this study. The porosity of the samples ranges from 60% to 70%. It was demonstrated that the biomimetic methods are suitable for inducing apatite on the titanium alloys surface.
259
Authors: Min Wang
Abstract: For hot rolling of titanium alloy large rings, rolling force is very important for designing, choosing and optimizing of processing plan and rolling mill. In the paper, the average shape parameter of the deformation zone of ring rolling is presented first, and then a reliable coupled thermo-mechanical three-dimensional (3D) finite element (FE) model for the process is developed. Finally, influences of the blank outer radius R0 and inner radius r0 on rolling force are discussed and compared for exploring blank thickness effects. The main results show that decreasing the blank thickness by decreasing R0 or increasing r0 leads to a saving of rolling force, while R0 has a predominant effect than r0.
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