Properties of Oxynitride Thin Films for Biomedical Applications

Several biomedical coatings on the basis of oxynitride compounds have been studied in the last 20 years. Published results will be presented on TiNbON, NbON, TiON and SiON. These coatings have been deposited by PVD methods, like cathodic arc evaporation and plasma immersion ion implantation and deposition. The aim of the studies was to improve the biomedical parts with respect to biocompatibility, corrosion resistance and mechanical strength, like hardness or wear resistance. The coatings have been characterized by elemental depth profiling, X-ray diffraction, nanohardness and wear tests. For SiON the platelet adhesion test and the enzyme-linked immunoassay method have been used. The latter two methods have proven that SiON has a better blood compatibility compared to low-temperature isotropic pyrolytic carbon (LTIC). Hence, SiON is suggested as a viable coating in blood-contacting medical products. Finally, the patent situation about oxynitride coatings for biomedical usage has been analyzed and will be briefly discussed.

Keywords: Biomedical coatings, PVD, cathodic arc evaporation, plasma immersion ion implantation and deposition, oxynitride, TiNbON, NbON, TiON, SiON, patents, diffusion barrier, chemical composition, structure, abrasive wear test, Ringer´s solution, cytotoxicity tests, platelet-adhesion test, water contact angles, enzyme-linked immunoassay method, blood compatibility.