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.