Tribological characterization of surface modified UHMWPE against DLC-coated Co–Cr–Mo

Abstract

The generation of wear particles from the ultra-high molecular weight polyethylene (UHMWPE) counter-face of Co–Cr–Mo/UHMWPE sliding pair is relatively high. These polyethylene wear particles lead to osteolysis and that result in the failure of the implant made with the Co–Cr–Mo/UHMWPE sliding pair. Hence, an investigation has been carried out to enhance the wear resistance of UHMWPE by surface modification of one or either of the sliding surfaces. Tribological characterizations were carried out on good quality diamond-like carbon (DLC) coatings prepared on UHMWPE with and without prior C-ion implantation by filtered cathodic vacuum arc (FCVA) technique in conjunction with high substrate pulse biasing, sliding against uncoated and DLC-coated Co–Cr–Mo. The evaluations are categorized into two groups: (1) unmodified and DLC-coated UHMWPE with and without prior carbon implantation sliding against uncoated Co–Cr–Mo, (2) DLC-coated UHMWPE with and without prior carbon implantation sliding against DLC-coated Co–Cr–Mo. The study reveals that by coating the UHMWPE with DLC coating protects the UHMWPE surface. However, the DLC coating causes severe Co–Cr–Mo wear. Coating both the sliding surfaces with DLC coating reduces the wear rates of the sliding surfaces to a greater extent. The DLC-coated UHMWPE with prior carbon implantation did not show any superior behaviour over that without prior carbon implantation.