Micro-arc formation of ZrO 2 ceramic coatings on AZ91D Mg alloy

Abstract

The aim of the work has been to prepare ceramic coatings containing the ZrO₂ phase on a Mg alloy by micro-arc oxidation technique. The phase composition of the coatings was examined with X-ray diffraction. The surface morphology and the elemental distribution of the coatings were studied with scanning electron microscopy and energy dispersive spectroscopy. The corrosion resistance of the coated samples was examined by the accelerated electrochemical method in 3˙5%NaCl solution. The coating was found to be composed of t-ZrO₂ and a little c-ZrO₂. There were many residual discharge channels in the coating surface, which made the elemental distribution and surface morphology uneven. The corrosion resistance of the coated samples was much better than that of the AZ91D substrate, from a pitting corrosion resistance and general corrosion resistance stand point.