Influence of Pulse Time on the Structural and Tribological Properties of Micro Arc Oxidized AZ91D Magnesium Alloy

Abstract

Micro arc oxidation process is recently developed as a promising surface modification technique applying high voltage and current density onto the light metals. The magnesium alloys exhibit nearly the lowest density among metallic structural materials but its poor characteristics in corrosion resistance, wear resistance, hardness and so on, limit its wide-range of applications. Through micro arc oxidation, thick and wear-resistant ceramic coatings are directly formed on the surface of magnesium alloys. In this study, oxide coatings were formed on AZ91D magnesium alloy in a silicate-based electrolyte by micro arc oxidation (MAO) process. MAO process was applied in an alkaline electrolyte with different pulse time and the contribution of applied pulse time in micro structural and wear resistance was systematically investigated. Structure, composition and tribological characteristics of the coatings were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and dry sliding reciprocating wear tests.