Silicon Oxycarbide Aerogels for High-Temperature Thermal Insulation
- Wednesday, 23 December 2009
A high-performance, silicon oxycarbide (SiOC) aerogel material is suitable for use as thermal insulation at temperatures approaching 1,200 °C. These aerogel composites were created using cost-effective and commercially available polymeric precursors (the polymethylsiloxane resin, SOC-A35, from Starfire Systems), thus enabling scaleup and mass commercialization. The SiOC aerogels exhibited bulk densities and thermal conductivities that rival traditional silica-based aerogels. Prolonged exposure to temperatures above 1,000 °C had virtually no effect on the thermal conductivity, surface area, pore volume, or pore diameter of SiOC aerogels.
This work has shown that the use of SOC-A35 leads to aerogel materials containing a significant concentration of carbidic species and limited amorphous free carbon. Substitution of the divalent oxide species in silica with tetravalent carbidic carbon has directly led to materials that exhibit increased network viscosity, reduced sintering, and limited densification. The SiOC aerogels produced in this work have the highest carbide content of any dense or porous SiOC glass reported in the literature at that time, and exhibit tremendous long-term thermal stability.