2011 Volume 52 Issue 8 Pages 1697-1700
The paper demonstrated the electrochemical corrosion properties of the oxide film of AZ91 Mg alloy subjected to plasma electrolytic oxidation (PEO) coating in an electrolyte containing zirconia and additional heat treatment. Surface observation revealed that a number of zirconia particles were successfully incorporated and were also uniformly distributed throughout the oxide film. After subsequent heat treatment, the relative fraction of Mg(OH)2 decreased whilst the fraction of MgO increased in the oxide film due to the dehydration reaction at 423 K. From the results of electrochemical impedance spectroscopy, the excellent corrosion resistance of AZ91 Mg alloy could be achieved via PEO coating together with annealing treatment. Electrochemical response underlying corrosion response of the present alloy was discussed in relation to equivalent circuit model.
