Effect of Plasma Electrolytic Oxidation Coating on Corrosion Behavior of Zirconium Alloy in Superheated Steam Condition

Plasma electrolytic oxidation (PEO) coating on Zr alloy was prepared, and the corrosion behavior was investigated under 400 & DEG;C/10.3 MPa steam condition. The surface morphology, roughness, element distribution, and microstructure of PEO coating after corrosion were analyzed. The results indicate that the PEO coating after corrosion presents the typical pores and pancake structure feature, and the surface roughness of PEO coating decreases after corrosion. The PEO coating corroded for 45 days shows the best electrochemical performance because the newly formed oxide gathers to repair the pores and cracks in the oxide/metal interface. The corrosion resistance of PEO coating decreases with the corrosion time increase because the microcrack in PEO coating is connected to generate a large transverse crack, and the corrosion media can access to oxidize the substrate through the crack during the long-term corrosion process.