Tribological behaviour of Cl-implanted TiN coatings for biomedical applications

The tribological behaviour of the prosthetic pair TiN coated stainless steel/ultra high molecular weight polyethylene (UHMWPE) may be improved by chlorine-implantation of the TiN surface. Friction and wear were determined using a pin-on-disk apparatus and the wear mechanisms were investigated through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Rutherford backscattering spectrometry (RBS) was used to determine the chlorine distribution profiles in the chlorine-implanted TiN coatings before and after the tribological experiments, while X-ray photoelectron spectroscopy (XPS) was used to characterize chemically the same samples. Chlorine-implantation led to a significant polymeric wear reduction when the lubricant was Hanks' balanced salt solution (HBSS). If bovine serum albumin (BSA) was added to HBSS, a strong decrease of both friction and polymeric wear was observed for implanted and non-implanted TiN coatings. The former case was explained by the formation of a titanium oxide layer on the TiN surface, while the latter derived from albumin adsorption.