Novel-structured plasma-sprayed thermal barrier coatings with low thermal conductivity, high sintering resistance and high durability

The microstructure of the ceramic topcoat has a great influence on the service performance of thermal barrier coatings (TBCs). In this study, conventional layered-structure TBCs, nanostructured TBCs, and novel-structured TBCs with a unique microstructure were fabricated by air plasma spraying. The relationship between the microstructure and properties of the three different TBCs was analysed. Their thermal insulation ability, sintering resistance, and durability were systematically evaluated. Additionally, their failure modes after being subjected to two kinds of thermal shock tests were analysed. The results revealed that the novel-structured TBCs had remarkably superior performances in all the examined aspects. The thermal conductivity of the novel-structured TBCs was significantly lower than those of the conventional and nanostructured TBCs both in the as-sprayed state and after thermal treatment for 500 h at 1100 degrees C. The macroscopic elastic modulus of the novel-structured TBCs after sintering at 1300 degrees C for 100 h was similar to those of the conventional and nanostructured TBCs in the as-sprayed state. During both a burner rig thermal shock test and a furnace cyclic oxidation test, the thermal shock lifetime of the novel-structured TBCs was much longer than those of the conventional and nanostructured TBCs. This study has demonstrated novel-structured plasma-sprayed TBCs with high thermal insulation ability and high durability.

Automated summary

This study has shown that the novel-structured thermal barrier coatings (TBCs) exhibit superior performance compared to conventional and nanostructured TBCs in terms of thermal insulation ability, sintering resistance, durability, and thermal shock lifetime. The thermal conductivity of the novel-structured TBCs is significantly lower than that of the other two types, even after thermal treatment. The macroscopic elastic modulus of the novel-structured TBCs is comparable to the conventional and nanostructured TBCs after sintering, and their thermal shock lifetime is much longer.