Preparation of Al2O3-SiO2 Aerogel by Supercritical Drying

Abstract Al2O3-SiO2 aerogel was prepared through sol-gel process and ethanol supercritical drying technology using aluminum chloride hexahydrate (AlCl3•6H2O) and tetraethoxysilane (TEOS) as precursors. Structures and properties of Al2O3-SiO2 aerogel were investigated by means of BET, XRD, SEM, FTIR, TG-DTA. At room temperature, the specific surface area of Al2O3-SiO2 aerogel was 574m2•g−1, and the average pore size was 26.34nm. The three-dimensional network skeleton was composed of leaf shape particles. Al2O3-SiO2 aerogel went through the transformation process of γ-AlOOH + amorphous SiO2 → γ-Al2O3 + amorphous SiO2 → Mullite (3Al2O3•2SiO2) when heat treatment temperature increased from room temperature to 1200°C. At 1200°C, the specific surface area was 162m2•g−1, the average pore size was 59.91nm.It was indicated that Al2O3-SiO2 aerogel possessed excellent high temperature stability and heat insulation performance.