Surface engineering has been emerging as one of the most promising techn ologies to improve the tribological properties of biomaterials with a view to ex tending the life span of medical implants. For example, some novel surface engineering t echniques including ion implantation of ultra-high molecular weight polyethylen e (UHMWPE) and thermal oxidation (TO) treatment of titanium alloy have been devel oped. However, the full potential of improving the wear resistance of orthopaedi c implants based on the UHMWPE/ Ti6Al4V system will not be realized until the tr ibological performance of this surface engineered tribo-system is fully charact e rized and the acting wear mechanisms are well understood. In this paper, a pin- o n-disc tribometer was employed to evaluate the tribological response of the fol l owing three tribo-systems: (1) untreated UHMWPE/untreated Ti6Al4V, (2) untreate d UHMWPE/TO-treated Ti6Al4V and (3) ion implanted UHMWPE/TO treated Ti6Al4V unde r water lubricated conditions. Experimental results show that the tribological pr operties of UHMWPE can be significantly increased by surface engineering its sur face and/or the counterface. This can be attributed to the hardened surface of U HMWPE via molecular structure modification induced by ion bean bombardment c oupl ed with the surface oxide layer on Ti6Al4V formed during TO treatment, which has favorable tribological compatibility with UHMWPE.
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