Improved wear resistance and low thermal radiative conductivity of a middle‐entropy tantalate Y0.5Gd0.5Ta0.5Nb0.5O4

Abstract

AbstractFerroelastic YTaO4 is a promising material for thermal barrier coatings (TBCs), and its thermal and mechanical properties can be further optimized by various methods. In this study, a ferroelastic middle‐entropy ceramic Y0.5Gd0.5Ta0.5Nb0.5O4 was synthesized by solid‐phase sintering, and its microstructures and thermophysical properties were key points. We determined the contributions of phonons and photons to total thermal conductivity, and a low thermal conductivity was obtained by inhibiting high‐temperature thermal radiation. The thermal expansion coefficients were improved by introducing of Nb atom into the lattice of the prepared middle‐entropy ceramic, which meets the requirements of TBCs. The improved wear resistance originated from relatively high Young's modulus and the hardness of Y0.5Gd0.5Ta0.5Nb0.5O4, and it would contribute to the service performance of the corresponding coatings. This work motivates the engineering applications of ferroelastic RETaO4 and RENbO4 (RE is rare‐earth element) as high‐temperature TBCs.