Effects of Infrared Scattering Powders on the Thermal Properties of Porous SiO2 Insulation Material

Porous SiO2 insulation material was made by wet process. Fibrous xonotlite crystal and glass fiber were used as reinforced fibers, and graphite, zirconia and titania powders were added as infrared scattering materials into the porous SiO2 insulation material. The density of the SiO2 insulation material was about 0.3g/cm3. The porosity was about 85%, and the pore size was mainly ranged from 20 to 60 nm in diameter. Heat transfer due to solid conduction and gas convection was reduced greatly because of the existence of larger amount of nano pores. Thermal radiation was partly blocked by the infrared scattering powders. Thermal conductivity of the porous SiO2 insulation material added with graphite powder as infrared scattering powder can reach as low as 0.04W/m.K at 700C. The type and amount of added infrared scattering powders had important influence on the thermal performances of insulation materials.