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 α-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.