INTEGRATION OF MINERAL POWDERS INTO SIO2 AEROGELS

Composites of SiO2 aerogels and mu m-sized mineral powders were produc ed in order to develop opacified thermally insulating materials for ap plication at temperatures up to 1000 degrees C. The opacification effe ct was observed by Fourier transform infrared spectroscopy in the wave length from 2 to 20 mu m. The albedo of the powders varied from 0.97 f or solely scattering TiO2 to 0.25 for mainly absorbing B4C. The extinc tion values of the pure SiO2 of below 1 m(2)/kg in the regarded spectr al range increased to about 60 m(2)/kg for an ilmenite-doped sample. A n increase of temperature stability of the aerogels was achieved by ad ding fine Al2O3 powder. It was demonstrated that doped SiO2 aerogels a re efficient high-temperature insulating materials.