Silica Glass from Aerosil by Sol-Gel Process: Densification and Textural Properties

Sol-gel processes allow the synthesis of inorganic materials from solutions of molecular precursors. These precursors can be either organic, inorganic, or a mixture of the two. The aim of this work is the preparation of aqueous solutions consisting of Aerosil OX 50 (fumed silica) using small amount of additives like ammonium fluoride NH4F (less than 2%), which are dried at room temperature in order to obtain monolithic gels. These are then densified at temperatures below 1200°C and siIntered at 1300°C in order to obtain pure silica glass. The textural properties evolution of these gels is investigated as a function of temperature by thermal analysis (mass loss, shrinkage, and density) and scanning electron microscopy.