Plasma Electrolytic Oxidation of AZ31 Mg Alloy in Bipolar Pulse Mode and Influence of Corrosion to Surface Morphology of Obtained Coatings

Abstract

The plasma electrolytic oxidation method was used with AZ31 magnesium alloy plates for improving the corrosion resistance of the alloy. Process parameters for the plasma electrolytic oxidation setup were optimized by studying the effects of KOH concentration, operating voltage, and pulse properties on the obtained coating. These conditions were then used to produce plasma electrolytic oxidation coated AZ31 sample and were tested by immersion in 3 % NaCl solution for 1 week. Three types of modifiers were used in the electrolyte and concentrations of the modifiers were varied to study the effect of concentration on the performance of coating obtained. The extent of corrosion was visually examined, and it was found that an electrolyte recipe with all three modifiers produced the best results.