Aerogels – Production, properties and applications

Abstract

Aerogels are highly porous sol-gel derived solids. Their properties, which are extremely fascinating as well as very promising for a large number of applications, are due to their nanostructure. Aerogels can be produced from a variety of materials, whereby silica aerogels are the most thoroughly studied ones. Silica aerogels with densities ranging from a few kg/m 3 to a few hundred kg/m 3 have been made as monoliths, in granular form or as powders. This paper describes the fundamentals of the sol-gel process, drying techniques and the basic aerogel properties. Special attention is given to their nanostructure and the resultant very low thermal conductivity. Most of the applications so far are based on the thermal, mechanical and optical properties of silica aerogels which are described.