Calcium-magnesium-alumina-silicate (CMAS) resistant high entropy ceramic (Y0.2Gd0.2Er0.2Yb0.2Lu0.2)2Zr2O7 for thermal barrier coatings

A novel high-entropy material, (Y0.2Gd0.2Er0.2Yb0.2Lu0.2)(2)Zr2O7 was successfully synthesized by the solid state reaction method and spark plasma sintering, and investigated as a promising thermal barrier coating material. Rare-earth elements were distributed homogeneously in the pyrochlore structure. It was found that the prepared high-entropy ceramic maintains pyrochlore structure at the temperature up to 1600 degrees C, and it possesses a similar thermal expansion coefficient (10.2 x 10(-6) K-1 at 25-900 degrees C) to that of YSZ, low thermal conductivity (< 0.9 W m(-1) K-1 at 100-1000 degrees C) and good CMAS resistance (infiltration depth is 22 mu m after annealed at 1300 degrees C for 24 h). The corrosion process was investigated, and RE elements distributing homogeneously in (Y0.2Gd0.2Er0.2Yb0.2Lu0.2)(2)Zr2O7 show different diffusion rates in CMAS. RE3+ with a larger radius (closer to Ca2+) is easier to react with CMAS to form an apatite phase. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.