Corrosion response of annealed oxide film of pure Mg via plasma electrolytic oxidation in an electrolyte containing KMnO4

The purpose of this study was to investigate the corrosion resistance of the annealed oxide film of pure Mg coated by a plasma electrolytic oxidation (PEO) in an electrolyte containing KMnO4. The effect of the annealing treatments subsequent to PEO coating on the structural development and corrosion characteristics of the PEO-treated pure Mg was studied. The addition of KMnO4 to the electrolyte significantly affected the thickness, surface morphology, and chemical compound of the oxide films. From the results of potentio-dynamic polarization and salt spray tests in a 3.5 wt.% NaCl solution, a superior corrosion resistance of pure Mg could be achieved via the PEO process in a KMnO4 containing electrolyte followed by an annealing treatment at 423 K. (C) 2011 Elsevier B.V. All rights reserved