Preparation and properties of aluminosilicate aerogels from boehmite and waterglass

Aluminosilicate aerogels are promising thermal insulation materials for high temperature applications. In this study, aluminosilicate aerogels were effectively synthesised using affordable precursors: dispersible boehmite powder and waterglass solutions, with subsequent drying achieved by supercritical CO2 processing. According to the evaluation of their properties, the Al–Si aerogels exhibited low densities (0.11 g/cm3), low thermal conductivities (<0.021 W/m·K) and high specific surface areas (SSA) (516 m2/g for an Al:Si molar ratio of 3:1). When waterglass-based aerogel and aluminosilicate samples were treated at high temperature (1200 °C), the formation of mullite was demonstrated for the aluminosilicate aerogel with a molar ratio of Al:Si 3:1, which showed a higher value for SSA compared to the waterglass-based aerogel.