Synthesis and properties of fire resistance and thermal insulation Si/Al/Zr aerogels

Silica aerogel is the most extensively studied and technologically mature material in the field of thermal insulation. However, the application of silica aerogel in high-temperature fields is limited because of its significant shrinkage above 800 °C, pore structure collapse, and high transmittance for near-infrared radiation. To overcome these intrinsic limitations, a series of Si/Al/Zr aerogels with varying Zr contents were synthesized via the sol-gel method in this study. The Si/Al/Zr aerogels exhibited low density (0.05–0.096 g cm −3 ) and low thermal conductivity (0.02754–0.02961 W (m K) −1 ). After heat treatment at 1100 °C for 2 h, the aerogel with a Zr/Si molar ratio of 0.24 demonstrated the highest specific surface area (303.29 m 2  g −1 ) and the largest pore volume (0.74 cm 3  g −1 ). The simulation results revealed that the maximum cold-face temperatures of the aerogel with a Zr/Si molar ratio of 0.32 and the AF/Zr-0.32 aerogel composite (Al 2 O 3 fiber blankets reinforced with Zr-0.32 aerogel) were 167.95 °C and 193 °C, respectively. Furthermore, the AF/Zr-0.32 aerogel composite exhibited outstanding fire resistance and thermal insulation properties. After 15 min of exposure to a 1300 °C butane flame, the temperature difference exceeded 802.9 °C between the back face and the exposed face. This novel aerogel system demonstrated great potential for advancing high-temperature fire resistance and thermal insulation technologies, effectively surmounting the limitations of traditional silica aerogels.