Electrochemical Behavior of Dental Ni-Cr Wirolloy Coated with Eco-friendly Films in Artificial Saliva

The electrochemical corrosion behavior of the non-precious Ni-Cr Wirolloy, being used in dentistry, was investigated before and after applying of two types of eco-friendly coatings, polyvinyl silsesquioxane (PVS) and nano-hydroxyapatite (nHAP) separately in artificial saliva solution at 37 degrees C for 14 d of immersion. The study aimed to investigate the effectiveness of the introduced coating films in enhancing the corrosion resistance of the alloy, and in decreasing the leaching of the toxic Ni ions from the alloy into the environment. The electrochemical corrosion investigation methods used are; open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The evaluated results revealed that the electrochemically coated alloy with PVS. prepared at cathodic potential showed higher corrosion resistance and more stable film compared to that prepared by conventional dip-coating method. At the same time, the nHAP electrochemically coated film provided the best anti-corrosion properties over all examined time intervals. The obtained results were confirmed via surface analysis, which assured the formation of the prepared coatings on the alloy surface. Chemical analysis of the corrosion product/solutions showed that the effect of electrochemically deposited nHAP and PVS. polymer films in suppression of Ni ions leaching is similar and slightly higher than that of the chemically coated PVS. one; however, all of them are efficient in decreasing the leaching of the risky Ni ions into the solution.