Microstructure of plasma-sprayed Al2O3-ZrO2 composite coatings

Thermal barrier coatings of Al2O3-ZrO2 were prepared by air plasma spraying on the surface of 20G steel. Phase constitution, microstructures and elemental distributions of the coatings were studied by X-ray diffraction, scanning electron microscope and electron probe X-ray microanalysis. The results show that the plasma spray coating mainly consists of alpha-Al2O3, c-ZrO2, and t-ZrO2. The bond state of the interface between the top layer and bond layer is fine, and the bond layer has a good combination with the substrate. ZrO2 and Al2O3 structures can closely integrate together and form compact top layer system.