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.