Micro-abrasion–corrosion of a Co–Cr/UHMWPE couple in Ringerʹs solution: An approach to construction of mechanism and synergism maps for application to bio-implants

In studies of tribo-corrosion, the degradation of bio-materials has become of increasing research interest in recent years. This is because, in many cases, the interactions of the tribological and corrosion component in biological environments are not well understood. Moreover, the wide range of variables involved in the tribo-corrosion process, and the variety of materials used in such conditions, mean that there are few systematic studies where materials and operating conditions are optimized. In the total replacement of hip joints, the Co–Cr/UHMWPE couple has been used widely. However, the application of any replacement joint for biological conditions will depend on many factors including the activity of the patient and the overall load imposed on the artificial joint. This means evaluation of the tribo-corrosion behaviour over a multi parameter space is important in order to assess the degradation possible for many patient/activity and body mass categories. In this work, the performance of a Co–Cr/UHMWPE couple was evaluated in Ringerʹs solution in a tribological situation where micron size particles were entrained in the contact – micro-abrasion–corrosion. The effects of applied load and potential were investigated in the study. Micro-abrasion–corrosion maps were constructed for the material indicating the mechanism of degradation, the extent of wastage and of synergy/antagonism involved in the tribo-corrosion interaction.