High-entropy (Y0.2 Gd0.2 Dy0.2 Er0.2 Yb0.2 )2Hf2O7 ceramic: A promising thermal barrier coating material

Thermal barrier coating (TBC) materials perform an increasingly important role in the thermal or chemical protection of hot components in a gas turbine. In this study, a novel high entropy hafnate (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 was synthesized by solution combustion method and investigated as a potential TBC layer. The as-synthesized (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 possesses a pure single disordered fluorite phase with a highly homogeneous distribution of rare earth (RE) cations, exhibiting prominent phase stability and excellent chemical compatibility with Al2O3 even at 1300 degrees C. Moreover, (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 demonstrates a more sluggish grain growth rate than Y2Hf2O7. The thermal conductivity of (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 (0.73-0.93 W m(-1) K-1) is smaller than those of components RE2Hf2O7 and many high entropy TBC materials. Beside, the calculated thermal expansion coefficient (TEC) of (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 (10.68 x 10(-6)/K, 1100 degrees C) is smaller than that of yttriastabilized zirconia (YSZ). Based on the results of this work, (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 is suitable for the next generation TBC materials with outstanding properties. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, a novel high entropy hafnate (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 was synthesized and characterized for potential use as a thermal barrier coating (TBC) material in gas turbines. The (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 demonstrated excellent phase stability, chemical compatibility with Al2O3, and lower thermal conductivity compared to other TBC materials. These results suggest that (Y0.2Gd0.2Dy0.2Er0.2Yb0.2)(2)Hf2O7 is a promising candidate for the next generation TBC materials.