عنوان مقاله [English]
Silica aerogels are nanoporous materials with an open-pore structure and interesting properties such as low density, high porosity, low thermal conductivity, high specific surface area, low refractive index and high optical transmission. These unique properties provide enormous potential for a variety of applications such as insulators, catalysts, optics, adsorbents and drug delivery systems. A common method for preparing silica aerogels is the sol-gel process, followed by supercritical drying/ ambient pressure drying. Better understanding of mutually dependent processing parameters and their adjustment such as type of precursor, molar ratio of components, pH of silica solution, aging and washing time, solvent exchange process and surface modification can produce good quality aerogels depending on their application. In the present study, a review on the preparation of silica aerogels using sodium silicate, the mechanism of gel formation and the effect of process parameters on the structure and their properties are presented. Finally, the most important applications of silica aerogel in engineering sciences and recent developments in this field are mentioned.