Effect of post-additive manufacturing surface modification temperature on the tribological and tribocorrosion properties of Co-Cr-Mo alloy for biomedical applications

Abstract

In this paper, the effect of post-additive manufacturing (AM) surface modification temperature on the tribological and tribocorrosion properties of Co-Cr-Mo alloy was investigated. A Co-Cr-Mo alloy, which is mainly used as a bearing surface for manufacturing a femoral head in MOM (metal-on-metal) bearings, was treated by ultrasonic nanocrystal surface modification (UNSM) at ambient temperature (AT) and high temperature (HT). This study aimed at reducing the coefficient of friction (COF), specific wear rate (SWR) and also at enhancing the tribocorrosion resistance (TCR) of AM-based Co-Cr-Mo alloy by the application of UNSM. UNSM at HT sample demonstrated better tribological and tribocorrosion properties than the UNSM at AT and the as-printed Co-Cr-Mo alloy samples. COF and SRW reduction and TCR enhancement mechanisms were comprehensively discussed based on the changes in surface morphology, microstructure and mechanical properties after UNSM at AT and HT. Several biomedical applications that are being used a cast/wrought Co-Cr-Mo alloy may be benefited from the reduction in COF and SRW, and enhancement in TCR of Co-Cr-Mo alloy manufactured by AM and a replacement of cast/wrought with AM-based one can be considered.