Comparative research on the effect of an oxide coating and a tribo-oxide layer on dry sliding wear of Ti–6Al–4V alloy

The effect of an oxide coating and a tribo-oxide layer on dry sliding wear of Ti–6Al–4V alloy was comparatively studied. The oxide coating was prepared on Ti–6Al–4V alloy by a thermal oxidation/diffusion process; the tribo-layer was an in situ produced mechanically mixed layer during dry sliding. The oxide coating markedly improved the wear performance of Ti–6Al–4V alloy at room and elevated temperatures. Tribo-layers were classified into three types: no-oxide tribo-layer, porous, and dense tribo-oxide layers. Both porous and dense tribo-oxide layer presented protective function, thus significantly improving wear performance of Ti–6Al–4V alloy. However, no other than dense tribo-oxide layer was qualified to be comparable to the oxide coating, which almost possessed the same wear-reduced function as the oxide coating. Even when the oxide coating was severely delaminated, the tribo-oxide layer would replace the oxide coating and took effect to protect from wear.