Dynamic surface microstructural changes during tribological contact that determine the wear behaviour of hip...

It is often the dynamic microstructural changes induced by tribological contact that determine whether or not a material exhibits good wear resistance. It is well known that the mechanical properties of a surface are significantly different from the bulk, an effect amplified by wear induced plastic deformation and electrochemical effects. Despite the importance of these dynamic microstructural changes, there remains little quantitative understanding of how the surface microstructure changes during tribo-contact, and how this modifies the surface mechanical properties and chemical activity. This contribution will focus on key total hip arthroplasty materials, specifically CoCrMo alloys, third and fourth generation alumina/zirconia toughened alumina. High resolution techniques have been used to characterise the wear induced microstructural changes for both in vivo and in vitro samples, which has provided new insight into the wear mechanisms. The results are discussed in detail, in particular, how they inform future materials development for this important application.