A study of corrosion behavior of 3YSZ coating on AZ91D alloy different interlayers

摘要

The zirconia stabilized by 3wt% Y_2O_3 (3YSZ) was applied onto the surface of the magnesium alloy AZ91D using electrophoretic deposition (EPD). Three interlayers of Ni-P, Zinc and aluminum between the substrate and YSZ coating were also prepared by electroless, electroplating and EPD process, respectively. 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 neutral solution. However, the results indicate that the YSZ coating improve the corrosion resistance of AZ91D alloy in chloride solution with different interlayers, the aluminum interlayer has a favorable effect on the densification of coating so that it improves significantly the corrosion resistance of AZ91D alloy. The YSZ coating with aluminum interlayer can increase in the charge-transfer resistance of the AZ91D surface in chloride solution and ends to increase the corrosion resistance of Mg alloy.