Formation of silicon-calcium-phosphate-containing coating on Mg-Zn-Ca alloy by a two-step micro-arc oxidation technique

Abstract Si-CaP containing coatings were deposited on a Mg-Zn-Ca alloy by the two-step micro-arc oxidation processes. The surface and cross-section morphologies, EDS analysis, phase composition and polarization curves of MAO coatings were investigated. With the increasing of the two-step voltages, the number of micro-pores tended to decrease and the surfaces became more compact while the thickness of coatings continually increased. In addition, the corrosion resistance of Mg alloy was greatly improved with the Si-CaP coatings, and the Mg alloy with Si-CaP coating prepared at 400 V had the best corrosion resistance.