Research progress on hafnium-based thermal barrier coatings materials

Thermal barrier coatings (TBC) are important materials applied to hot part components of aero-engines in order to improve their service temperature. Increasing inlet temperature is an important factor to achieve elevated thrust-to-weight ratio and high heat engine efficiency. In recent years, traditional TBC materials have gradually reached their operating limits due to the increase in turbine operating temperature. Hafnium-based materials become promising new candidates for TBC because of the similar structure, higher temperature phase stability and lower thermal conductivity compared to traditional zirconium-based materials. In this review, recent progresses in the research and development for hafnium-based TBC materials are summarized. The phase stability, thermal and mechanical properties of rare-earth (RE)-doped HfO2 and RE hafnate materials are introduced. REdoped HfO2 has good thermal properties and phase stability at high temperatures whereas relatively low fracture toughness. The RE hafnates possess the advantages of a higher phase transition temperature, lower thermal conductivity and superior fracture toughness than RE zirconates. However, the thermal expansion coefficients of most RE hafnates are quite different from the alloy matrix. Finally, further research directions for hafnium-based TBC materials are prospected in this study.

Automated summary

Thermal barrier coatings (TBC) are applied to improve the service temperature of hot part components in aero-engines. Hafnium-based materials have shown promise as a new candidate for TBC due to their structure, temperature stability, and thermal conductivity compared to traditional zirconium-based materials. This review summarizes recent progress in the research and development of hafnium-based TBC materials, including the phase stability, thermal and mechanical properties of rare-earth-doped HfO2 and RE hafnate materials. The review also discusses the challenges and future directions for hafnium-based TBC materials.