Changes in the microstructure of an acid-catalyzed silica gel have been studied through the gel to glass conversion temperature. The gel composition selected was known to produce a dense silica glass at 1000°C that was not distorted or cracked. Surface area, porosity and pore size distribution were measured. Shrinkage during constant rate heating was observed. Effects of heating rate and atmosphere on densification were noted. An optimum heating rate of 2.5°C/min, which is a balance between the temperature dependence of the viscosity and the temperature dependence of the dehydroxylated surface tension, was found to give the greatest shrinkage below 1000°C.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry