Preparation of monolithic Al₂O₃–SiO₂ aerogels with high-temperature resistance using boehmite nanorods

In this study, monolithic Al₂O₃–SiO₂ aerogels with excellent thermal stability were synthesized by ambient pressure drying (APD) or supercritical drying (SCD) using tetraethyl orthosilicate and boehmite nanorods (L = 20–30 nm, D = 3–5 nm) as precursors. The high specific surface area of aerogels prepared by APD or SCD was maintained after calcination at 800 °C (585 m²/g or 664 m²/g), 1000 °C (415 m²/g or 487 m²/g), and 1100 °C (175 m²/g or 231 m²/g). The anti-sintering mechanism of the aerogels prepared with boehmite nanorods as the aluminum source was discussed in detail. Successful preparation by APD offers the possibility of low-cost and large-scale application of monolithic Al₂O₃–SiO₂ aerogels. Al₂O₃–SiO₂ aerogels with excellent thermal stability have the potential to be used as high-temperature thermal insulating materials in aerospace applications.