Wear characteristics of surface oxidation treated new biomedical β-type titanium alloy in simulated body environment

Wear resistance in one of the important characteristics for biomaterials. An excessive friction wear is one of the main causes of looseness in artificial hip joints because the progress of wear depresses the mobility and load capacity of the artificial hip joints. While, titanium and its alloys are well known to have excellent biocompatibility among the metallic materials. However, wear resistance of titanium and its alloys is considerably lower than that of Co-Cr alloy and SUS316L stainless steel, which are conventional biomaterials. In this study, therefore, the oxidation treatment was carried out to improve wear resistance of Ti-29Nb-13Ta-4.6Zr, a new β-type titanium alloy, and Ti-6Al-4V ELI, a typical conventional titanium alloy, for biomedical applications. The following results were obtained. In oxidized Ti-29Nb-13Ta-4.6Zr, the α phase precipitates below oxide layer on the specimen surface. The highest hardness is obtained in the vicinity of boundary between oxide layer and oxygen solution layer in oxidized Ti-29Nb-13Ta-4.6Zr. When the oxidation treatment is conducted with T-29Nb-13Ta-4.6Zr, oxygen solute in the alloy is greater than that in Ti-6Al-4V ELI. Therefore, the oxide layer of Ti-29Nb-13Ta-4.6Zr shows no exfoliation. For an oxidation treatment temperature of 773K, weight loss of Ti-29Nb-13Ta-4.6Zr decreases with increasing treatment time. However, weight loss of Ti-6Al-4V ELI increases in this case. For an oxidation treatment temperature of 1073K, weight loss decreases in both Ti-29Nb-13Ta-4.6Zr and Ti-6Al-4V ELI with increasing treatment time. From the above results, it can be concluded that oxidation treatment is the effective way to improve wear resistance of Ti-29Nb-13Ta-4.6Zr.