Optimized Technics of Supercritical Drying of SiO_2 Aerogel

Silica aerogels were prepared through a two-step catalyzed sol-gel route and ethanol supercritical drying technique.A four-factor,three-level orthogonal experiment was designed to investigate the influence of technological parameters of ethanol supercritical drying on the density of resulting SiO2 aerogel.The optimized parameters are 400 mL of ethanol,8 MPa of pre-pressure,270 ℃ of supercritical temperature and 12 MPa of supercritical pressure.Density of silica aerogel prepared under this condition is only 0.091 1 g/cm3.The microstructure of the aerogel was investigated by SEM,TEM and FTIR.