Structrure of Al2O3 Ceramic Coating on Super Alloy Prepared by Cathodic Plasma Electrolytic Oxidation

Abstract

Al2O3ceramic coating was successfully prepared on GH132 super alloy by cathodic plasma electrolytic oxidation in (NO3)3·9H2O electrolyte. The structure and chemical composition of the coatings were characterized. The results showed that the as prepared coating was composed of Al2O3crystal, including much α-Al2O3andsomeγ-Al2O3two types of Al2O3.A few Fe elements entered into in the substrate and nearly no other elements were found in the coating surface. The Al2O3.coating showed coarse surface and there were some small pits on the surface. The diameters of pits were not more than 20 um. The thickness of coating was about 50μm.