Microstructures and properties of plasma-sprayed segmented thermal barrier coatings

Thermal barrier coatings (TBCs) with different levels of segmentation crack density were produced by spraying two types of ZrO₂-8Y ₂O₃ powders. The fused and crushed powder has a greater capability of forming segmented coatings than the hollow sphere (HOSP) one. The highly segmented coatings reveal much lower porosity compared with traditionally sprayed coatings, thereby compromising the property of thermal insulation of TBCs. Microstructure and thermal conductivity of the HOSP coatings are more sensitive to the changes in spray conditions. Segmentation cracks had a strong influence in decreasing Young's modulus of coatings. Fifty hours heat treatment at 1250°C had little effect on the mechanical property of the highly segmented coatings.