Microarc Electrodeposition of Ceramic Coatings on Double Electrodes of AZ91D Magnesium Alloy by AC Pulse Method

It was carried out successfully to microarc electrodeposit ceramic coatings on the anode and cathode of AZ91D magnesium cast alloy with AC pulse method. The thicknesses, morphologies, composition and micro-structures of the coatings were studied by scanning electron microscopy (SEM) and X ray diffraction (XRD). Rare earth element as Ce can deposit in the anode and cathode ceramic coatings on AZ91D cast alloy besides that both electrodes have formed the same characteristic ceramic coatings. By comparing the electrochemical impendence spectroscopies (EIS) and potentiodynamic scanning polarization curves of the anode and cathode coatings, it was found that microarc oxidation (MAO) coatings on the anode and cathode of AZ91D have better corrosion resistance than that of bare AZ91D magnesium cast alloy.