Protective performance of Zr and Cr based silico-oxynitrides used for dental applications by means of potentiodynamic polarization and odd random phase multisine electrochemical impedance spectroscopy

Zr and Cr based silico-oxynitrides were deposited on CoCr dental alloys by cathodic arc evaporation method, at two bias voltages. Potentiodynamic polarization and ORP-multisine EIS were employed to assess the performance of the coatings during 72 h of immersion in artificial saliva. Enhanced corrosion resistance was exhibited by coatings deposited at higher bias voltage, ascribed to the beneficial effect of the more intense ion bombardment during the deposition, which determined a defect-free structure. Among them, ZrSiON200 coating exhibited the highest protective performance in time to the CoCr substrate ascribed to the formation of a stable passive layer inhibiting the corrosion.