Effect of Oxidation Time on the Structure and Properties of LAZ933 Magnesium-Lithium Alloy Micro-Arc Oxidation Thermal Control Coating

Abstract

The thermal control coating was prepared on the surface of LAZ933 magnesium-lithium alloy by micro-arc oxidation technology. The effects of oxidation time on the surface morphology, composition, thickness, roughness, thermal control and corrosion resistance of the coating were analyzed by scanning electron microscopy, X-ray diffractometer, surface profilometer, thickness gauge and other instruments. Results showed that as the oxidation time gradually prolonged, the number of pores on the coating surface gradually decreased, the pore size gradually rose with the emergence of microcracks, and the thickness and roughness of the coating gradually were raised. Meanwhile, the hemispherical emissivity gradually increased, the solar absorption ratio declined, and the corrosion resistance was improved. When the oxidation time was 60 min, the as-obtained coating possessed the hemispherical emissivity of 0.85 and the solar absorption rate of 0.38, and the self-corrosion current density was an order of magnitude lower than that of LAZ933 magnesium-lithium alloy.

Keywords

• magnesium-lithium alloy; micro-arc oxidation; thermal control coating; corrosion resistance