Corrosion Resistance Investigations of Prosthetic Dental Alloys Coated by TiN

Objectives: The aim of this study was to ascertain if and to what extent TiN coatings increase the corrosion resistance of and decrease metal ion release from NiCr- and CoCr- based dental alloys.
Methods: Two kinds of non-precious dental alloys: HERAENIUM-NA and VIRONIT were coated with TiN using the arc-PVD method. The coatings were examined by means of diffraction techniques and X-ray microanalysis in order to determine the chemical composition and structure of their layers. The approximate thicknesses of layers were measured. Corrosion behaviour was examined. The amount of ions from the metallic base penetrating through the coating into the corrosive solution was determined. The OCP versus time measurements and potentiodynamic polarization technique were used to determine the corrosion resistance of the coated samples. The surfaces of samples were observed using SEM.
Results: In general, more ions were released from both uncoated alloys. The OCP v/s time plots and polarization curves indicated that the TiN coated alloys exhibited better corrosion resistance.
Conclusions: TiN coatings on Ni-Cr and Co-Cr alloys may improve the corrosion resistance and decrease metal ion release. It is suggested that TiN coatings could have an application in prosthetic dentistry under conditions of procedures optimalization in order to obtain more dense compact layers.

Keywords: Ni-, Co-based Alloys, Tin, Corrosion Resistance, Ion Release, Electrochemical Tests, SEM