Aerogel

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  • Topic: Aerogel, Thermal insulation, Thermal conductivity
  • Pages : 4 (1128 words )
  • Download(s) : 53
  • Published : March 1, 2013
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Today, I’m going to explain how aerogel (otherwise known as frozen smoke) is so unique to any other known materials in the world.
An aerogel is a synthetic porous ultra-light material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density  and thermal conductivity. Nicknames include "frozen smoke", "solid smoke", "solid air" or "blue smoke" owing to its translucent nature and the way light scatters in the material; however, it feels like expanded polystyrene (Styrofoam) to the touch. Aerogel was first created by Samuel Stephens Kistler in 1931, as a result of a bet with Charles Learned over who could replace the liquid in "jellies" with gas without causing shrinkage. Aerogels are produced by extracting the liquid component of a gel through supercritical drying. This allows the liquid to be slowly dried off without causing the solid matrix in the gel to collapse from capillary action, as would happen with conventional evaporation. The first aerogels were produced from silica gels. Kistler's later work involved aerogels based on alumina, chromia and tin dioxide. Carbon aerogels were first developed in the late 1980s. Properties

Despite their name, aerogels are solid, rigid, and dry materials and do not resemble a gel in their physical properties; the name comes from the fact that they are derived (composed) from gels. Pressing softly on an aerogel typically does not leave even a minor mark; pressing more firmly will leave a permanent depression. Pressing extremely firmly enough will cause a catastrophic breakdown in the sparse structure, causing it to shatter like glass – a property known as friability; although more modern variations do not suffer from this. Despite the fact that it is prone to shattering, it is very strong structurally. Its impressive load bearing abilities are due to the dendritic microstructure, in which spherical particles of average size 2–5 nm are fused...
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