Electrophoretic deposition of 3YSZ coating on AZ91D using an aluminum interlayer

The zirconia stabilized by 3 mol % Y2O3 (3YSZ) was applied onto the surface of the magnesium alloy AZ91D using electrophoretic deposition (EPD) from a non- aqueous solvent. An interlayer of aluminum between the substrate and YSZ coating was also prepared by EPD. The preparation, microstructure and corrosion resistance of the coatings were investigated. The surface morphologies of the coatings were studied by scanning electron microscopy (SEM) and their compositions were determined by X-ray diffraction (XRD). The corrosion resistance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results indicate that the aluminum interlayer has a favorable effect on the densification of the coating by formation of aluminum oxide. In addition, the corrosion resistance of coated AZ91D alloy in chloride solution is significantly improved because of the aluminum interlayer and an increase in charge-transfer resistance of the AZ91D surface in chloride solution was observed which was attributed to YSZ.