Failure Analysis And Stress Simulation On Plasma Sprayed Al₂O₃ Ceramic Coating

The purpose on this paper was to analyze the failing mechanism of Al₂O₃ ceramic coating. The corrosion experiment, which was to submerse coating into liquid zinc, was carried to compare with thermal shock experiment that heat and cool the coating. After experiment, the coating was analyzed by SEM, XRD. Resulting from corrosion experiment, some compound such as ZnO·Al₂O₃,3ZnO·47Al₂O₃,4ZnO·11Al₂O₃were produced and the amount of the compound depend on ZnO. However, the coating was deteriorated slowly. While after thermal shock, resulting from the different coefficients of thermal expansion between the coat and subtract, the coating cracked and was cut off.. Therefore, the main failing form of the coating is through thermal shock.At last, the stresses of the coating were simulated by ANSYS. The stresses of the coating were acquired and stress value in the coating was larger than in the subtract. The stresses in coating were tensile stress, which was correspondent to the result that coating cracked after thermal shocks, the more thermal shocks, the bigger the tensile stress was.