Fabrication and microstructural characterization of silica aerogel by aging additional pressurization

SiO2 aerogel with Light-weight and low thermal conductivity is a promising candidate for thermal insulator used for aerospace vehicles. In this paper, we report the preparation and microstructural characterization of SiO2 aerogel by aging pressurization using supercritical drying method. The results showed that the aging pressurization can rapid increase the bulk density from 0.1g/cm3 to 0.45g/cm3 with the pressure changing from 200Pa to 600Pa. When the pressure increases to 800Pa, the density was increased to 0.46g/cm3 slowly. Further polycondensation is driven by the increasing of contact area between skeleton particles when the aging pressure increased. The grid structure became densification and saturation when the aging pressure approached 800Pa. SEM method gives the evidence of increase of aging pressure, which can help to increase the size of secondary grains. Nitrogen sorption-desorption measurements exhibit an unimodal pore distribution and low specific area and porosity with the increase of aging pressure. Real density test showed that the bulk density increased by pressure. Bulk density, gain size and pore structure distribution can be controlled effectively by aging pressurization