Development of composite thermal barrier coatings with anisotropic microstructure

A novel ZrO2-Al2O3 thermal barrier composite coating was produced using a g as-tunnel-type plasma spraying torch. To enhance visualization of the micro structure features, image enhancement techniques were used during the micro photograph digitization processes. The unique microstructure features of th is composite coating include a relatively even distribution of embedded thi n ZrO2 splats in a Al2O3 matrix, parallel alignment of the ZrO2 splats rela tive to the substrate surface, absence of porosity between the ZrO2 splats and the Al2O3 matrix, etc. This anisotropic composite coating combined with the large difference in thermal conductivity between ZrO2 and Al2O3 will a lter the thermal behavior of the coating. (C) 2000 Elsevier Science Ltd. Al l rights reserved.