PREPARATION AND INVESTIAGATION OF HIGHLY EFFECTIVE THERMAL INSULATIONS:SILICA AEROGELS DOPED WITH TiO_2 POWDER AND CERAMIC FIBER

Silica aerogels are nanoporous materials produced in a sol-gel process followed by supercritical drying.The tenuous solid skeleton and the nanosized pores of the materials lead to very low solid and gaseous thermal conductivities.The radiative conductivity decreases dramatically in opacified silica aerogels.TiO2 powder is chosen as an opacifier to reduce the radiative heat transport. The ceramic fiber is doped in to increase the mechanical property. The thermal concuctivity of the monolithic silica aerogels doped with Tio2 powder and ceramic fibers were investigated by varying the gas pressure and the temperature. Results show that the doped silica aerogel with a density of 260kg/m3 has a total thermal conductivity of 0.038W(m·K)-1 at 800K in air.The development of such low thermal conductivity materials is of great interest with respect to thermal insulation at high temperature.