Comparison of the mechanical properties and electrochemical behavior of TiN and CrN single-layer and CrN/TiN multi-layer coatings deposited by PVD method on a dental alloy

Metallic materials used in medicine and dentistry should have high corrosion resistance and high biocompability. In this study, the influence of TiN, CrN and TiN/CrN layers on the hardness, surface roughness, and the corrosion resistance of Ni–Cr ceramic dental alloys in an artificial saliva environment (pH = 8) were evaluated. Ni–Cr dental alloys were produced by lost-wax casting and the TiN, CrN and TiN/CrN nanolayer coatings were deposited by means of arc-physical vapor deposition method. The microstructural characterization of selected alloys was performed before and after electrochemical tests, using scanning electron microscopy, energy dispersion spectroscopy, and x-ray diffraction. The surface roughness of the alloys was investigated by Profilometer. Surface characterization of the passive layer formed on the coated and uncoated Ni–Cr dental alloys in artificial saliva was studied using impedance spectroscopy measurement. The results showed that hardness of the ceramic-coated materials is noticeably greater than that of the uncoated substrate. Also, polarization and impedance spectroscopy measurements revealed that CrN coating has an exceptionally high polarization resistance compared to Ni–Cr dental alloy and TiN and TiN/CrN coatings.