Enhancement of wear resistance for improved functional performance of Co-Cr-Mo hip implants through cryogenic surface treatment: a case study

This study was to determine to what extent a cryogenic surface treatment technique could improve the wear resistance of a Co-Cr-Mo hip implant material. Dry and cryogenic treatments were used to create different surface and sub-surface conditions. The Co-Cr-Mo samples were wear-tested using a pin-on-disk tester in a simulated implant environment. A change in the wear response was found as a function of the material surface properties. Correlation between the treatment conditions and wear volume loss was discussed. Sample from cryogenic treatment was found to be most promising with lower wear volume due to microstructure refinement, compressive residual stresses and preferred hcp phase; moreover, the preferred hcp phase revealed to be the most influencing property in enhancing the wear resistance.