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Microstructure and Corrosion Properties of AZ91D Magnesium Alloy treated by Plasma Electrolytic Oxidation  

Chang, Si-Young (Department of Materials Engineering, Korea Aerospace University)
Kim, Ye-Lim (Graduate Student, Korea Aerospace University)
Kim, Yang-Do (School of Materials Science and Engineering, Pusan National University)
Publication Information
Journal of Korea Foundry Society / v.28, no.1, 2008 , pp. 20-24 More about this Journal
Abstract
The characteristics, such as roughness, thickness, microhardness and corrosion resistance, of plasma electrolytic oxide coatings on AZ91D alloy were investigated under the processing condition of various coating times. The coatings on AZ91D alloy consisted of MgO, $MgAl_{2}O_{4}$ and $Mg_{2}SiO_{4}$ oxides. The surface roughness and thickness of coatings became larger with increasing the coating time. The microhardness in cross section of coatings was much higher than not only that in surface but that in the conventional anodic oxide coatings, which increased progressively as the coating time increased. After being immersed in 3.5%NaCl solution and methyl alcohol, the corrosion resistance of AZ91D alloy was markedly improved by plasma electrolytic oxidation coating treatment, and the AZ91D alloy coated for 50min revealed excellent corrosion resistance.
Keywords
Plasma electrolytic oxidation; AZ91D alloy; Roughness; Thickness; Microhardness; Corrosion resistance;
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