Optimized Micro-Arc Oxidation Coating Thickness on ALZ Magnesium Lithium Alloy

摘要

Micro-arc oxidation (MAO) is known as a novel technique to use for the modifying the surface of valve metal, which improve mechanical and corrosion resistance properties. In this study, MAO coatings are fabricated on ALZ magnesium lithium alloy to protect the substrate from corrosion using environmentally friendly electrolytes under a high voltage power supply. The Taguchi method is used to identify the effects of current density, coating time and electrical frequency on the thickest coating uniformity. The optimum coating properties are characterized by coating thickness measurement, Scanning electron microscopy (SEM), Potentiodynamic polarization analysis. It was found that the processing time is the main factor affecting the thickest coating uniformity (t_u). Coatings fabricated under optimum conditions are in close agreement with the predicted values of Taguchi analysis. The corrosion resistance of MAO coated on ALZ magnesium lithium alloy are greatly improved compare to the bare alloy in corrosive environments.