Study on Alumina-based Nano Composite Coating Prepared by Plasma Spray

In order to obtain nano-structured ceramics composite coating for high temperature application, pre-mixed Al₂O₃/Y₂O₃ powders were plasma-sprayed in this study. Plasma spraying of spray-dried Al₂O₃/Y₂O₃ powder resulted in the formation of amorphous coating of metastable Al₂O₃-Y₂O₃ solid solution. After the heat treatment, α-Al₂O₃/YAG nano-structured composite coating was successfully obtained via eutectic reaction between Al₂O₃ and Y₂O₃. It was possible to control the sizes of Al₂O₃ and YAG particles widely by heat treatment with proper condition. Hardness of the coatings showed close relationship with their microstructure.