New Method for Producing Aerogels

Scientists from the Leipunsky Physioenergetic Institute (Obninsk) have developed a new aerogel technology. Aerogel is obtained by oxidation of aluminium dissolved in liquid gallium.

The aerogel synthesis is usually carried out by three stages. At first, a colloidal solution is prepared. Then organic solvent substitutes the water and alcogel is obtained. On the third stage, they dry alcogel in special autoclaves. The scientists from the Leipunsky Physioenergetic Institute have proposed to obtain aerogel according to absolutely different scheme: by oxidation of aluminium dissolved in liquid gallium. The scientists took advantage that aluminium has more oxygen affinity then gallium.

To obtain the material they solve about 1% of aluminium in liquid gallium and blow argon mixed with a water vapour through the smelt. Aluminium is oxidized, tied with water, and light white flakes are obtained. Hydrogen forming in chemical reaction evidently makes a lacing structure with open pores. With correct process parameters, gallium will not interact with the water vapour, and it can be used for following cycles of aluminium solving-water vapour bowing.

A particle of the aerogel consists of amorphous alumina long fibres at the thickness of 20-100 nm. This morphology doesn't change very much after the aerogel tempering at the temperature below 1300oC. The tempering is done to evaporate water tied with alumina from the material. Its properties: a density is 13-80 kg/m3, a heat conduction is 0,02 Bt/m.K, an electrical resistance is more than 10^10 Om.m, a specific surface area is more than 2000 m2/g are comparable with aerogel obtained by usual technology.

For more information contact to Radomir Ashadullin from the Leipunsky Physioenergetic Institute (Obninsk). Tel: +7 (08439)9-46-56, e-mail: martinov@okclub.org