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 center dot K)) and good compressive strength (53.17-129.65 kPa). The HENFPC sintered at 800 degrees C with 1 wt% agarose content exhibited the lowest roomtemperature thermal conductivity of 0.0339 W/(m center dot K). Besides, when the front side temperature of HENFPCs reached above 1300 degrees C, the back side temperature was only about 200 degrees C. The temperature difference over 1100 degrees C revealed HENFEPCs get excellent thermal stability as ideal lightweight high-temperature thermal insulation materials.