Effect of hydrogen peroxide on Cr oxide formation of additive manufactured CoCr alloys during plasma electrolytic polishing

Abstract

Hydrogen peroxide (H2O2) was utilized as a strong oxidizing agent to accelerate the oxidation of the cobalt-chromium (CoCr) alloy during the plasma electrolytic polishing (PEP) process, resulting in the growth of a chromium oxide layer. From the TEM results showing the increased thickness of the oxide film, it was obvious that the dose of H2O2 accelerated the growth of the oxide film which was composed of only Cr2O3. The added H2O2 also seemed to make the oxide film less defective in terms of the acceptor concentration, resulting in the improved corrosion resistance. Electrochemical impedance spectroscopy (EIS) results revealed that the increase in the corrosion resistance mainly came from the increased charge transfer resistance (Rct).