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 degrees C (585 m2/g or 664 m2/g), 1000 degrees C (415 m2/g or 487 m2/g), and 1100 degrees 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.