Characterization of ceramic coating on ZK60 magnesium alloy prepared in a dual electrolyte system by micro‐arc oxidation

Abstract

Abstract Micro‐arc oxidation (MAO) process was carried out in an optimized dual electrolyte system to fabricate a compact, smooth, and corrosion resistant coating on ZK60 Mg alloy. The microstructural characteristics of coating were investigated by scanning electron microscopy (SEM) coupled with an energy dispersive spectrometer (EDS) and X‐ray diffraction (XRD). Test of mass loss was conducted at a 3.5 % NaCl solution to assess the resistance to corrosion. The bonding strength between the coating and ZK60 substrate was evaluated using scratch experiment. The results reveal that MgAl 2 O 4 and MgO are the main phases of ceramic coating obtained in the dual electrolyte system. The corrosion rate of coating prepared in the optimized dual electrolyte is only 0.0061 g·m −2 ·h −1 , which demonstrates excellent corrosion resistance. This is mainly due to the compact, uniform coating with high bonding strength.