PREPARATION AND CHARACTERIZATION OF MONOLITHIC SILICA AEROGELS

We present the experimental results on the preparation and characteriz ation of silica aerogels. The aerogels have been prepared by hydrolysi s and condensation of tetraethoxysilane using a catalyst followed by s upercritical drying in an autoclave. Transparent and homogeneous silic a sols have been obtained using acid catalysts. The effect of catalyst concentration on the density of the aerogels has been studied. It has been observed that the density of the aerogels increases with increas e in concentration of the catalyst. Silica aerogels with densities ran ging from 0.08 to 0.6 g/cm3 have been obtained. A total temperature-pr essure cycle period of twelve hours has been found to give transparent and monolithic aerogels. The aerogels have been characterized by infr ared spectroscopy and density measurements.