Influence of microstructure of HC CoCrMo biomedical alloys on the corrosion and wear behaviour in simulated body fluids

The corrosion and tribological behaviour of an as-cast High Carbon CoCrMo alloy subjected to different thermal treatments in simulated body fluids has been analyzed by electrochemical techniques. After the microstructural characterization of the alloy, the samples were studied electrochemically and tribo-electrochemically. Thermal treatments influence the corrosion behaviour, passive dissolution and tribological response. An increase of grain boundaries accelerates the anodic reaction in all solutions. A higher carbide volume fraction generates a lower wear-rate. Microscopic observation by means of Optical and SEM microscopy showed that presence of proteins modified the debris behaviour. In non-protein containing solutions particles are dispersed away from the track while in protein solutions particles tend to agglomerate and sediment around the wear track.

Research highlights
► Thermal treatments are thought to be a good alternative to improve metal implant design by increasing the corrosion resistance and tribological properties. However, deeper insight in the tribocorrosion mechanisms is needed in order to evaluate their future performance in implant design.
► To study the influence of microstructure on the tribocorrosion behaviour of CoCrMo biomedical alloys in simulated body fluids is therefore an important issue. Relation between chemical composition of the electrolytes and the wear and corrosion behaviour will be highlighted.
► Importance of third body behaviour in wear and corrosion mechanisms will be discussed.