Enhanced corrosion resistance of AZ91 Mg alloy by plasma electrolytic oxidation with KMnO4

Abstract

The plasma electrolytic oxidation (PEO) process on AZ91 alloy was performed with an electrolyte containing potassium permanganate (KMnO4). Potassium permanganate in the electrolyte affected the film thickness, surface morphology and microstructure of oxide layers obtained by the PEO process. Oxide layers on AZ91 Mg alloy was confirmed as a mixture of MgO and Mn 2O3. The corrosion resistance of this sample was superior to that of the sample processed in the bath without KMnO4due to the presence of manganese oxide in the oxide layer.