Rare-earth zirconate high-entropy nanofibrous porous ceramics for high-temperature thermal insulation applications

Fibre-based porous ceramics are widely used as high-temperature insulation materials due to their good chemical stability and excellent thermal insulation performance. However, the potential roles and mechanical properties of high-entropy fibrous porous ceramics have rarely been explored. In this study, rare-earth zirconate (Dy0.2Y0.2Ho0.2Er0.2Yb0.2)2Zr2O7 (DYHEY) high-entropy nanofibrous porous ceramics (HENFPCs) were prepared using short-cut fibres by gel-casting combined with freeze-drying. The DYHEY HENFPCs exhibited very high porosity (93.86%–97.50%), low thermal conductivity (0.0339–0.0741 W/(m·K)) and good compressive strength (53.17–129.65 kPa). The HENFPC sintered at 800 °C with 1 wt.% agarose content exhibited the lowest room-temperature thermal conductivity of 0.0339 W/(m·K). Besides, when the front side temperature of HENFPCs reached above 1300 °C, the back side temperature was only about 200 °C. The temperature difference over 1100 °C revealed HENFEPCs get excellent thermal stability as ideal lightweight high-temperature thermal insulation materials.