The resistance to wear and corrosion of laser-cladding Al_2O_3 ceramic coating on Mg alloy

摘要

The paper presents a study on the preparation of Al_2O_3 ceramic coating on AZ91HP Mg alloy by laser remelting plasma-sprayed coating. It was found that after laser remelting, the coating exhibited obvious layer-like characteristics due to influence of temperature distribution, thermo-physical parameters and layer thickness. According to the microstructural difference, the coating can be divided into the melted zone with the α-Al_2O_3 column-like crystal, the sintered zone with flock-like structure, the residual plasma-sprayed zone with loosened structure. Because of the dense column-like crystal, the hardness, wear and corrosion resistance of the laser remelted coating are much higher than those of the plasma-sprayed coating and as-received Mg alloy.