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Tuesday, November 10, 2009

Aerogel




 


Do you know what is this ?? This is Magic haha, No way.


This is a piece of the lightest and lowest-density solid known to exist. 
This is Aerogel.


This material is a porous solid, and it is derived from a gel, it's made by drying a gel, called alcogel, then by extracting the liquid from the solid silica component.


The alcogel is dried by evaporating the solvent off, then the remaining component of the alcogel (the silica) collapses under capillary action, this solid is known as Xerogel (Xero=dry, gel=gel) , This xerogel is used in making contact lenses and high purity lenses.


But If you want to see the aerogel, this is not the method, in our scenario the alcogel is will be supercritically dried instead of evaporating the solvent. This process prevents the gel from collapsing, and in the same time you remove the liquid from the gel. So how can we do this.


This is simply done by heating the gel past its solvent's critical point, when the liquid leaves the body of the gel, the solvent gets out as a gaseous substance.
he remaining solid is made of silica, with tiny pockets (nanopores) filled with air, and is 50-99% of the volume of the original alcogel.  This solid is called an aerogel. 







Stardust Dust Collector with aerogel



NASA used aerogel to trap space dust particles aboard the Stardustthermal insulation of the Mars Rover and space suits. spacecraft. The particles vaporize on impact with solids and pass through gases, but can be trapped in aerogels. NASA also used aerogel for
This is how they also discovered the Glycine from comet Wild 2


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 inside of a jam jar with gas without causing shrinkage.
The first aerogels where based on silica, but this is not the only component an aerogel can be made from , Kistler's later work involved aerogels based on alumina, chromia and tin oxide. Carbon aerogels were first developed in the late 1980s.



Aerogel is typically 50-99.5% Air , you will think that this porous  material that's cmoposed of Air can't hold anything, but that's not true. In fact aerogel can hold 500 to 4000 times its weight in applied force (in theory).


Aerogel can have surface areas ranging from 250 to 3,000 square meters per gram, meaning that a cubic inch (2.5 cm x 2.5 cm x 2.5 cm) of aerogel flattened-out (again theoretically) would have more surface area than an entire football field!   


Aerogel's superlow density makes it useful as a lightweight structural material, and its superhigh internal surface area makes it a superinsulating solid material.  For those of you who have always wanted to touch an aerogel, it feels like styrofoam.  Silica aerogel is transparent with a blue cast.








 By the way I may touch one soon [Insha'Allah], Perhaps I will get a sample from NASA by the end of this month, If I was choosen from 100 person who filled a survey at the StarDust Mission website.