Magnesium alloy; ceramic composite coatings; microarc oxidation; corrosion resistance.
The magnesium alloys occupy an important place in marine applications, but their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To meet these defects, some techniques are developed. Microarc oxidation is a one such recently developed surface treatment technology under anodic oxidation in which ceramic coating is directly formed on the surface of magnesium alloy, by which its surface property is greatly improved. In this paper, a dense ceramic oxide coating, ∼ 20 𝜇m thick, was prepared on an Y1 magnesium alloy through microarc oxidation in a Na3SiO3–Na2WO4–KOH–Na2EDTA electrolytic solution. The property of corrosion resistance of ceramic coating was studied by CS300P electrochemistry–corrosion workstation, and the main impact factor of the corrosion resistance was also analysed. Microstructure and phase composition were analysed by SEM and XRD. The microhardness of the coating was also measured. The basic mechanism of microarc coating formation is explained in brief.
The results show that the corrosion resistance property of microarc oxidation coating on the Y1 magnesium surface is superior to the original samples in the 3.5 wt% NaCl solutions. The microarc oxidation coating is relatively dense and uniform, mainly composed of MgO, MgAl2O4 and MgSiO3. The microhardness of the Y1 magnesium alloy surface attained 410 HV, which was much larger than that of the original Y1 magnesium alloy without microarc oxidation.