Characterization and thermal properties of (YErYbGdLa)2Zr2O7 high entropy ceramic aerogel

Advanced ceramic aerogel has been much highlighted as an emerging lightweight thermal insulation material, but problems such as structural collapse or shrinkage at high temperature greatly limit practical applications. In this work, (YErYbGdLa)₂Zr₂O₇ high entropy ceramic aerogel (RZ) was prepared using rare earth salts, through the sol-gel method followed by CO₂ supercritical drying techniques and high-temperature calcination. Moreover, the RZ was successfully synthesized after heat treatment at 850 °C, exhibited a typical “pearl chain” three-dimensional (3D) porous structure. The microscopic morphology and thermal properties were also investigated after examination at different temperatures. Results showed that the RZ exhibited exceptional structural and phase stability at a temperature of 1400 °C for 2 h. Subsequently, the RZ reinforced by mullite fiber felt was calcined at high temperature and annealed for 2 h (FARZ). The original low density (0.1824 g·cm⁻³) and low thermal conductivity (0.0263 W·m⁻¹·K⁻¹ at 25 °C, 0.126 W·m⁻¹·K⁻¹ at 1000 °C) of the aerogels were maintained. The back temperature of the 10 mm thick FARZ was only 125 °C following exposure to a butane blowtorch flame at 1300 °C for 600 s. In addition, these results were well supported by theoretical ANSYS-Fluent simulation results. It had excellent thermal insulation performance and was expected to be applied in the ultra-high temperature thermal protection of spacecraft in the future.