A variety of cellular SiO2 materials have been synthesized using a foaming sol-gel process and their properties have been characterized. The process uses the rapid viscosity change during gelation to stabilize the structure of a foamed silica sol. It was found that the properties of these cellular materials are determined by method used. For example, the porosity and strength of these porous oxides depend on method of agitation and addition of Freon during the foaming process.
Density measurements, viscosity measurements as a function of pH, optical characterization, x-ray crystallography, ultimate compressive strength, dielectric constant measurements and thermal diffusivity were used to characterize these porous SiO2 materials. This paper will discuss the synthetic processes used to develop the porous silicas and properties of these materials.