Titanium Nitride Coatings on Ti Alloys by PIRAC for Orthopedic Implants

摘要

In the present work,Ti and Ti-6Al-4V were PIRAC nitrided at the relatively low temperatures of 700-850°C.To obtain thicker TiN layers,3 stage PIRAC based coating was applied:(1) PIRAC nitriding followed by (2) PIRAC titanizing followed by (3) additional PIRAC nitriding.The microstructure and phase composition of the obtained surface layers were characterized employing X-ray diffraction and scanning electron microscopy with chemical analysis (SEM/EDS).Bending test was employed to evaluate the coatings adhesion to the substrate.Lower PIRAC nitriding temperatures yielded smoother TiN coatings with a more gradual microhardness decrease from the surface to the bulk.All PIRAC TiN based coatings have excellent adhesion to substrate-no delamination of the coating in bending tests was observed.The best combination of microhardness and adhesion was obtained using 3 stage PIRAC process.