Lighter Than Air

While looking around for a ceramic material to blog about I came across something called aerogel.  Aerogel, also known as frozen smoke, solid smoke, and solid air, is an extremely porous solid materials that kinda feels like Styrofoam.  Aerogel is so porous you can actually see right through some types.  It is the lightest recorded solid on Earth with some weighing only 3 times more than air.

Now why does this material matter?  It matters because despite its low weight and density aerogel can support in compression 4000 times it weight.  That's like supporting the weight of a car on your back.  Since aerogel is so light and porous it makes an excelling heat and electrical conductor.  The huge gaps of air inside its structure makes it difficult for heat to move through it.  However like most ceramics it still very brittle.  Just watch this intro video about aerogels.

That has gotta be hot?  No, not really.

Aerogels are commonly made out of materials like silica, carbon, or alumina.  To make aerogel the ceramic material is mixed together in a liquid solution made of alcohol and other things with long complicated names.  When these materials are added together they create a complex interlinked microstructure that stops the flow liquid.  When the liquid stops moving this material is call a gel.  Now the key to making a good aerogel is how liquid is removed.  By allowing liquid to normally evaporate form the gel it is possible that the movement of liquid out destroys part of the microstructure.  To avoid this aerogel is often placed in high pressure high temperature environments that evaporates the liquid in it place, thus preserving the microstructure.

Aerogels are currently being used in areas like window insulation.  NASA has a number of uses aerogel including insulation in the Mars Rover and spacesuits.  NASA also used aerogels to trap space dust on the Stardust spacecraft.  Space particles normally vaporize when the contact solid materials.  Companies like Dunlop are even using them in tennis rackets.

If you want to know more about aerogels I found this amazing blog with all kinds of information.  The blog is called "aerogel.org."