Tribological characterisation of diamond-like carbon coatings on Co–Cr–Mo alloy for orthopaedic applications

A study has been carried out to examine the feasibility of high quality diamond-like carbon (DLC) films prepared on Co–Cr–Mo alloy by the filtered cathodic vacuum arc (FCVA) technique, as an enhanced wear resistant coating for artificial joints made of Co–Cr–Mo/UHMWPE sliding pairs. The tribological characterisation of Co–Cr–Mo alloy with and without DLC coating sliding against UHMWPE counter-surface in different tribological environments such as ambient air, DI (de-ionised) water and simulated body fluid (SBF), shows that the wear resistance of the DLC coated Co–Cr–Mo/UHMWPE sliding pair does not show much improvement over the uncoated Co–Cr–Mo/UHMWPE sliding pair. However, the hardness and corrosion resistance of the Co–Cr–Mo alloy is increased to a greater extent by the DLC coating. The effect of substrate surface roughness on the quality of DLC coatings has also been investigated, as part of the study. The analysis shows that the DLC coating prepared on rougher substrates displays shorter sliding life when tested with a harder counter-face such as sapphire ball.