INTEGRATION OF MINERAL POWDERS INTO SIO2 AEROGELS

Composites of SiO2 aerogels and mu m-sized mineral powders were produced in order to develop opacified thermally insulating materials for application at temperatures up to 1000 degrees C. The opacification effect was observed by Fourier transform infrared spectroscopy in the wavelength from 2 to 20 mu m. The albedo of the powders varied from 0.97 for solely scattering TiO2 to 0.25 for mainly absorbing B4C. The extinction values of the pure SiO2 of below 1 m(2)/kg in the regarded spectral range increased to about 60 m(2)/kg for an ilmenite-doped sample. An increase of temperature stability of the aerogels was achieved by adding fine Al2O3 powder. It was demonstrated that doped SiO2 aerogels are efficient high-temperature insulating materials.