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Making aerogel

The basic process is to make a silica-methanol gel, replace the methanol with liquid CO2, then carefully adjust the temperature and pressure to move the CO2 into supercritical and then to gas to prevent the silica matrix from being destroyed by the liquid CO2 suddenly evaporating.

I would not have thought you could do that in such a simple piping setup. It's just a cross with a sight glass, some gauges, and drains. Makes sense, I guess, as that gives a constant volume system to make the T/P changes to control the phase. That is definitely why he replaced the methanol with CO2 - you wouldn't want supercritical methanol in such a simple setup.
 
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Aerogel is an amazing lightweight thermal insulator, because it is mostly gas trapped within a small amount of solid to give it structure and strength.

I always wondered if it was feasible to manufacture large slabs to use it as an insulator for construction and if the performance difference with available materials would make it worth it.
 
I always wondered if it was feasible to manufacture large slabs to use it as an insulator for construction and if the performance difference with available materials would make it worth it.

I know it was used on a Mars rover, so it has specialty applications like that due to its low weight.

In terms of R-value, for one inch of material in ft^2*deg F*hr/Btu:

  • Vacuum - 14-66 (dependent on how much gas is evacuated and the material containing the vacuum)
  • Aerogel - 10.3
  • Polyurethane sheet - 7-8
  • Fiberglass sheet (i.e. typical home insulation)- 2.5
So 4-5 inches of fiberglass would have roughly the same resistance as 1 inch of aerogel, and aerogel is 28% more resistant to flux per inch than polyurethane. Aerogel is 73% as resistant as (probably) low quality vacuum insulation per inch.
 
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