Microstructural evolution in silica aerogel

Microstructural evolution in silica aerogel has been observed in samples produced by the hydrolysis and polycondenzation of tetramethylorthosilicate that was acid catalyzed. Drying of the silica gel was performed by replacing its liquid phase with liquid carbon dioxide, which was removed under high pressure and low temperature conditions in a critical point dryer. Different stages of microstructural evolution have been observed through a thermal process from room temperature to 1500 °C in a conventional furnace. In addition, microstructural characterization has been performed using nitrogen adsorption, helium pycnometry, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetrical analysis. The primary goal of this work is to fully understand the microstructural evolution of silica gel so it may be used more extensively in developing ceramic materials with novel, designed microstructures.