Crystallization Behavior of Novel Al₂O₃-YAG Amorphous Ceramic Coating Deposited by Atmospheric Plasma Spraying

Al2O3-YAG amorphous ceramic coating is expected to apply to harsh wear service due to its excellent crack propagation resistance, but the crystallization of this coating may affect its service stability. Therefore, the crystallization behavior of the Al2O3-YAG coating prepared by atmospheric plasma spray (APS) was investigated in this study. The results showed that this coating had excellent microstructure stability over a broad temperature range and had a higher activation energy during non-isothermal crystallization process. The isothermal DSC curves showed that the crystallization process of this coating was controlled by the change in external thermodynamic conditions. The grain growth mechanism for alpha-Al2O3 and YAG was from three-dimensional direction bulk growth to one-dimensional direction flake thickening. The calculated fragility index showed that the amorphous ceramic coating had better stability and higher plastic deformation capacity than other typical brittle materials at its critical temperature range.