New surface modification for Ti-6Al-7Nb alloy: oxygen diffusion hardening (ODH).

PVD-TiN coating and N+ implantation of Ti-6Al-7Nb alloy resulted in surface hardening to a depth of less 3 microns. The new oxygen diffusion hardening (ODH) treatment increased the hardness gradually to 50 microns. PUD-TiN showed an improvement in the tribological properties, while N+ implantation increased the PE wear rate. The wear rate of the ultrahigh-molecular-weight as well as the friction coefficient were reduced to one-half of the values achieved with the combination of CoCrMo-alloy when paired against the ODH-treated surface. In pairing with ZrO2-containing bone cement the ODH-treated surface showed only a minimal reaction.