Material Aerogels
Aerogels are highly porous, transparent metal oxide materials.They are very light (the lightest have a density of only 3 times that of air, i.e. 0.003 g/cm3), and have good heat resistance (up to 800 C) and insulation as the picture of the flower shows.

They have an extremely high surface area (600-1000 m2/g) and acoustical insulation (sound speed through an aerogel is only 100 m/s). They are the product of the supercritical drying of a sol-gel produced alcogel. The most important are made of silica.

The combination of their properties makes them attractive for a number of applications such as window panes, refrigeration insulators, sound insulators, shock adsorbers for safety devices, pollutant adsorbers and storage containers for rocket fuels.
Danish Name Aerogels
Products Window pane, aerogel (USA)
Window pane, aerogel (Europe)
Processes Sol-gel
Supercritical drying
Similar materials Nanocomposites metal salt
Nanocomposites photoluminiscent
Chlorofluorocarbon-blown polyurethane foams.
References Airglass AB
DTU, Department of Building and Energy
Lawrence Berkeley National Lab
Lawrence Livermore National Laboratory
Price 3000-4000 DKK per one 2-4 dm2 sheet
Environmen- tal notes Creation: The production of silica aerogels is environmentally benign. No significantly hazardous wastes are generated during their production.
Use: Silica aerogels are completely non-toxic and non-flammable.
Disposal: The disposal of silica aerogels is perfectly natural. In the environment, they quickly crush into a fine powder that is essentially identical to sand.
Additional Info Supercritical drying removes liquid from a "wet" gel substituing it with air, without shrinkage. Aerogels are available only for laboratory tests, at very high prices. Their mass production (~10 years) will sharply decrese their price.
Photo Lawrence Berkeley National Laboratory
Copyright © 1997,98,99 Torben Lenau
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