Thermal cycling property of the novel Hf6Ta2O17/YSZ TBCs prepared by atmospheric plasma spraying technology

Abstract

Hf₆Ta₂O₁₇, with low thermal conductivity, high thermal expansion coefficient, and excellent fracture toughness, was a promising candidate ceramic top coat material of thermal barrier coating (TBC). A novel Hf₆Ta₂O₁₇/YSZ double ceramic top coat prepared by atmospheric plasma spraying (APS) was applied to study the role of the microstructure and mechanical property on the thermal cycling property at 1200 °C. Results show that the rapid decomposition of Hf₆Ta₂O₁₇ occurred during the spraying process. As the increased spraying power, more HfO₂ phases were observed in the Hf₆Ta₂O₁₇/YSZ TBCs. Besides, the porosity of the Hf₆Ta₂O₁₇ ceramic top coat decreased with the increased spraying power, resulting in the elastic modulus of the Hf₆Ta₂O₁₇ ceramic top coat enhancement. The highest cycles at 1200 °C were obtained for the Hf₆Ta₂O₁₇/YSZ TBCs with the lowest elastic modulus and least HfO₂ phases, and were twice as long as the cycles of the single YSZ TBCs. The chemical reaction between HfO₂ and Hf₆Ta₂O₁₇ might have contributed to the cracking of the Hf₆Ta₂O₁₇/YSZ TBCs. This work provides a new option for the preparation and development of the ternary oxides by APS.