Isothermal sintering of SiO2-aerogels

摘要: Isothermal sintering has been studied for two base-catalyzed SiO2-aerogels with initial densities ρ0 = 122 kg/m3 and 256 kg/m3, covering a temperature range from 750 to 950 °C time periods up 200 h; the highest density achieved was 339 kg/m3. The change in at given is compared predictions of theories. elastic constants determined by ultrasonic measurements reveal scaling upon sintering. Microscopic structural changes during have means small angle X-ray scattering (SAXS). Characteristic parameters are mean diameter particles, i.e. building blocks gel network, size macropores within tenuous structure specific surface area. major finding investigations observation processes different scales: fast reduction accompanied slow decrease area as well slight increase particle diameter. For both samples investigated all can be unequivocally correlated - independent density.