Monolithic Al2O3-SiO2 aerogels enhanced by hybrid interpenetrating network with high mechanical strength and excellent thermal insulation

Oxide ceramic aerogels, one of the most important aerogels, hold significant application promise in thermal insulation and protection. However, their low strength, long preparation cycle, and supercritical drying dependence hinder their widespread use. In this study, we proposed a hybrid interpenetrating network strategy and prepared a hybrid Al₂O₃-SiO₂ aerogel (PAS) via ambient pressure drying. The structures, mechanical properties, thermal insulation performance, and mechanisms of PAS were systematically investigated. PAS exhibited remarkably low drying linear shrinkage (6.08 %), substantially compressive strength (8.05 MPa), and impressive strain capacity (45 %). Furthermore, PAS demonstrated exceptional thermal insulation (0.039 W/m·K at 25°C) and high-temperature structural stability. Mechanistic studies revealed that the hybrid interpenetrating network significantly reinforced the Al₂O₃-SiO₂ network, and inhibited the phase transition of Al₂O₃-SiO₂ in high-temperature. This study provides a reproducible approach for the rapid preparation of high-strength, low-thermal conductivity oxide ceramic aerogels and demonstrates its promising application potential in thermal protection.