Wear and corrosion protection of 316-L femoral implants by deposition of thin films

Abstract

The wear and corrosion attack on mobile components of surgical implants, like femoral prosthesis, are one of the responsible of its short lifetime. Ceramic thin films like TiN, ZrN, NbN, VN and HfN are commonly used as protective coatings because they possess high hardness, electrochemical immunity and biocompatibility. Thin films of transition metals nitrides and multilayers of Ti/TiN and Cr/V were deposited on 316-L stainless steel and silicon using reactive magnetron sputtering. The coatings were characterized with respect to microhardness using an ultra micro hardness tester Fisher HV100P and with respect to the abrasive wear resistance using a mechanical simulator for hip prosthesis developed in our laboratory. The abraded surfaces were investigated with scanning electron microscopy as function of the number of cycles in the simulator (steps). The corrosion resistance of the coated 316 L stainless steel has been carried out in a potentiodynamic polarization in an aqueous solution environment. Elemental composition has been obtained by Rutherford backscattering (RBS), energy dispersive spectroscopy (EDS) and X-ray fluorescence analysis (XRF) and the crystal phases structure has been studied with X-ray diffraction (XRD). The better compromise among stoichiometry, microstructure, wear resistance, hardness and corrosion protection indicate that a multilayer containing transition metal nitrides (Ti/TiN) are a serious candidate to be applied as protective layer on femoral implants.