Thickness effects on corrosion and wear resistance properties of micro-arc discharge oxide coatings on AZ91D magnesium alloys
(1.重庆市重庆科技学院材料科学与工程学院
2.School of Materials Science and Engineering, Chongqing Institute of Technology, Chongqing 400050, China)
2.School of Materials Science and Engineering, Chongqing Institute of Technology, Chongqing 400050, China)
Abstract: The microarc oxidation coatings with difference thickness were synthesized on AZ91D magnesium alloy. The microstructure and phase structure of the coatings were analyzed using SEM and XRD, the tribological properties and corrosion resistance behaviour of the coatings were also investigated. The results show that the coating contains two layers, a porous outer layer and relatively dense inner layer. The microhardness of the MAO coatings is four to six times higher than that of the magnesium alloy substrate. The MAO coatings have much better wear-resistance and corrosion resistance abilities than those of magnesium alloy substrate, but possess higher friction coefficient. The results further indicate that there is an optimization thickness for corrosion and wear resistance.
Key words: magnesium alloy; micro-arc oxidization; wear; corrosion; ceramic coating