Frictional wear characteristics of biomedical Ti-29Nb-13Ta-4.6Zr alloy with various microstructures in air and simulated body fluid

The frictional wear characteristics of Ti-29Nb-13Ta-4.6Zr alloy subjected to solution treatment (referred to as TNTZ_ST) and aged at 598, 673 and 723 K after solution treatment (referred to as TNTZ_598K, TNTZ_673K and TNTZ_723K, respectively) were investigated in air and a simulated body environment (Ringer's solution) as a function of the loading level. Ti-6Al-4V ELI alloy aged at 813 K after solution treatment (referred to as T64_STA) was employed as a reference material. Wear weight losses of TNTZ_ST, TNTZ_598K, TNTZ_673K, TNTZ_723K and Ti64_STA are lower in Ringer's solution than in air under both low and high loading conditions (1.96 and 29.4 N, respectively). It is considered that the frictional factor decreases because of the lubricating effect of Ringer's solution between the contact surface of the specimen and the zirconia ball - the mating material. Moreover, the wear weight losses of TNTZ_598K, TNTZ_673K and TNTZ_723K are lower than that of Ti64_STA in both air and Ringer's solution under the low loading condition, but are higher under the high loading condition. This result implies that the transition from severe wear to mild wear versus loading level depends on the type of material.