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

Abstract

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.

Keywords:

• Hip implant
• phase structure
• surface modification
• wear

Acknowledgments

The authors would like to thank Air Products and Chemicals for providing the ICEFLY^® liquid nitrogen delivery system. Special thanks to Professor J.C. Outerio from the Catholic University of Portugal for providing the opportunity to conduct residual stress analysis. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.