aerogel

Aerogel is a translucent, synthetic solid-state substance with extremely low density and excellent thermal insulating properties. Also known as "frozen smoke," aerogel in its solid form has a texture similar to that of foamed polystyrene.

Aerogels are the lightest solid materials in existence -- a man-sized block (6' x 2.5' x2.5') of the substance weighs less than a pound. However, if evenly dispersed, that one-pound, man-sized block could support the weight of a subcompact car (around 1,000 lbs).

Aerogel is approximately 99.8% air by volume. It does not conduct thermal energy well, it is almost totally opaque to infrared radiation (IR) and it prevents thermal convection by impeding the flow of air. Because of these properties, some engineers and scientists believe aerogel will eventually become prevalent in the manufacture of energy-efficient buildings for use in regions where temperature extremes often occur.

The two most common types of aerogel are derived from silicon and carbon. Aerogels are created by replacing the gel's liquid content with air or a gas of some kind. Heat treatment helps to stabilize structure and prevent shrinkage.Silica aerogel is a good electrical insulator as well as a thermal insulator. Carbon aerogel has similar low density as well as excellent temperature stability. Some forms of carbon aerogel are reasonably good electrical conductors. Carbon aerogel is available as a solid, as a powder or as composite paper.

Aerogel was used as an insulating material in the Mars Rover. Other current or potential uses of aerogels include:

• insulating pads to protect users from the heat of laptop computers
• thermally insulating windows
• microchip sand other components where insulating materials with low dielectric constant s are required
• pigments for printer ink
• a component of toothpaste
• interception and detection of some high-speed subatomic and cosmic particles
• as an agent for the removal of toxic metals from water
• bullet-proof armor
• as a replacement for paper in loudspeaker cones
• anti-reflective coatings
• lightweight fibers and composites
• super- capacitor carbon electrodes .

Read more about it at: > This page explains the use of aerogels as energy-efficient building materials. > This NASA document refers to aerogel as 'frozen smoke' > This document from the Microstructured Materials Group explains the history of silica aerogels. > This Sol-Gel Gateway article explores various solid gel forms and their potential.

Last updated on: Nov 22, 2007

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