Mechanical characteristics and corrosion behavior of (Ti,Al)N coatings on dental alloys

Titanium aluminum nitride films were deposited on special dental alloys by reactive RF sputtering to modify the characteristics of nickel-based and chromium-based dental material. The surface hardness of the (Ti1−x,Alx)N films was measured by nanoindentation testing. The hardness of the films was enhanced by the introduction of aluminum as compared to pure TiN films. Nanoindentation tests showed that the surface hardness of the (Ti1−x,Alx)N was as high as 35GPa for an x value of 0.45. The sliding pin-on-disk method was performed to investigate the wear resistance of the coatings as compared with dental alloys without any coatings. The friction coefficient of (Ti1−x,Alx)N films against cemented tungsten carbide was lower than that of uncoated dental alloys. In addition, to simulate the body environment, corrosion test was carried out in 0.9% NaCl solution. The morphology and microstructure of the coatings were analyzed by X-ray diffractometry and scanning electron microscopy. A lower corrosion current density was achieved for Ti0.75Al0.25N-coated dental alloy, as compared with uncoated dental alloys. In addition, the pitting corrosion was substantially reduced by the employment of TiAlN coating.