Effects of heat treatment on microstructures and physical properties of segmented thermal barrier coatings

Highly segmented thermal barrier coatings (TBCs) were produced by "hot" plasma spraying. The effects of heat treatment on the microstructures, mechanical and thermophysical properties were studied. The segmented coatings are denser than traditionally plasma-sprayed TBCs due to its good insplat bonding at high substrate temperature. The segmentation cracks and associating branching cracks hardly propagated or closed during sintering process, indicative of a good stability of crack network. Due to its low porosity, the segmented coatings compromised the property of thermal insulation of TBCs. For the coatings after 24 h heat treatment at 1523 K, the thermal conductivity was improved by around 35%. The segmentation cracks had a strong impact on decreasing the Young's modulus. Heat treatment could not effectively promote the increase of the Young's modulus, especially for the case of highly segmented coatings.