Synthesis of Silica Aerogel Using Silica Sol by Ambient Drying Method

摘要

In this experiment, silica sol was used as raw material, the mixture of ammonium chloride and ammonia was used as coagulant. After replacing the solvent with n-hexane, silica aerogel was obtained under the condition of normal pressure. The influence of sol pH and coagulating temperature on the gel time was studied. According to the SEM photographs, the influence of drying temperature from 30°C to 60°C on the microstructure of silica aerogel was analyzed. This study showed that when sol pH was 6.5, coagulating temperature was 80°C and the concentration of ammonia was 0.4 mol/L, the gel time was the shortest. The average size of silica aerogel particles was 10-20 nm, the average size of apertures was 20-50 nm. When the drying temperature was 40°C, the specific surface area was 402.41 m /g, the pore volume was 2.33 cm~3/g, the density was 0.18 g/cm~3.