Micro-Arc Oxidized Corrosion Resistant Interlayer on Magnesium Alloy with Electromagnetic Wave Absorption Coatings

An interlayer film between a magnesium alloy substrate (MAS) and electromagnetic wave absorption coatings (EWACs) has been produced by micro-arc oxidation (MAO) method. A new voltage mode has been developed for use in the MAO technique. The corrosion resistance of MAS has been investigated in 3.5 wt% NaCl solution. The results show that the MAO interlayer not only delays interaction of chloride electrolyte with MAS but also changes corrosion behavior of the metal substrate. The film restricts propagation of filiform corrosion at the coating/substrate interface and simultaneously eliminates galvanic couples by separating absorbents in the EWAC from the MAS.