Optimizing additive Y2O3 concentration for improving corrosion resistance of ceramic coatings formed by plasma electrolytic oxidation on Zr-4 alloy

Abstract

Abstract The corrosion resistance of ceramic coatings developed by plasma electrolytic oxidation (PEO) can be improved by embedding particles. Optimizing the concentration of particles in the electrolyte is essential to obtain the best coating performance. This work aims to optimize the concentration of Y2O3 embedded in the PEO coatings on Zr-4 alloy to obtain the best corrosion resistance. Nanoparticles Y2O3 was suspended in the PEO electrolyte at a concentration of 2, 3 and 4 g l−1. The particles were successfully embedded in the PEO coating composed of ZrO2–SiO2. The electrochemical test in an aqueous solution and oxidation test at 600 °C revealed a consistent result that the best corrosion resistance was obtained in the coating formed in the 3 g l−1 Y2O3-containing electrolyte. At the corresponding optimum concentration, the coating contained high SiO2 and tetragonal (t) ZrO2 phase, which potentially formed a stable solid solution ZrO2–SiO2. The improved coating stability enhanced the corrosion resistance during both aqueous solution and high temperature exposure.