Microstructure and fretting behavior of hard TiN-based coatings on surgical titanium alloys

An original nitriding method [powder immersion reaction assisted coating (PIRAC)] for improving wear resistance of Ti-based surgical alloys was developed. CP Ti and Ti–6Al–4V alloy samples were annealed in sealed stainless steel containers that allow selective diffusion of nitrogen atoms from the atmosphere. The microhardness-microstructure and nitrogen concentration relationship were studied for TiN-based PIRAC coatings grown at 850–1100°C. Phase identification and microstructure characterization of nitrided samples were performed by XRD, SEM/EPMA and HRSEM. The effect of PIRAC coating on fretting behavior of Ti–6Al–4V was studied in vitro under conditions simulating in vivo conditions at the interface of modular orthopedic implants. A significant reduction in friction coefficient and fretted areas was measured for the coated samples.