Microstructure and Corrosion-Resisting Properties of CeO2-SiO2-Al2O3 Composite Coatings Prepared by Plasma Electrolytic Oxidation on Aluminum Matrix Composites

CeO2-SiO2-Al2O3 composite coatings were prepared on aluminum matrix composites by plasma electrolytic oxidation in the electrolyte of a silicate system consisting of Na2SiO3 and NaOH. The effects of the content of the soluble salt additive Ce(NO3)(3)6 H2O on the microstructure, elemental composition, phase structure, thickness, corrosion resistance, and resistance to high-temperature oxidation of the PEO coatings were systematically investigated. The results showed that the CeO2-SiO2-Al2O3 ternary composite ceramic coatings were prepared with the main components of the physical phases as alpha-Al2O3, gamma-Al2O3, Al, and SiC. And the addition of Ce(NO3)(3)6 H2O increased the thickness of the coatings from 14.75 mu m to 82.71 mu m. Meanwhile, densification showed a tendency to increase and then decrease with the concentration of Ce(NO3)(3)6 H2O. The surface microscopic morphology of the PEO coatings was optimized with the increase of the added concentration when the Ce(NO3)(3)6 H2O concentration was lower than 1.0 g/L, and the surface quality of the coatings deteriorated when the Ce(NO3)(3)6 H2O concentration was higher than 1.0 g/L. The corrosion resistance of the coatings was improved when the concentration of Ce(NO3)(3)6 H2O was increased to 82.71 mu m by the electrochemical experiments and the cavitation experiments. The corrosion resistance of the coatings was optimized when the concentration of Ce(NO3)(3)6 H2O was added at 1.0 g/L, the coating's corrosion resistance was optimized.