SCIENCE FACTS

 

What is aerogel

Aerogels are nanoporous solids invented in the 1930’s.
Aerogels are created when silica is gelled in a solvent.
When the solvent is removed, what remains is “puffed-up” sand, with up to 99% porosity.

Nanoporosity slows heat and mass transport, providing record-low thermal conductivity.

  Pores are 1/10000 the diameter
of a human hair
Aerogels are often called
«frozen smoke»

Aerogel has the lowest thermal conductivity

  Thermal conductivity
(mw/m-K)
Aerogel 13
Polyurethane Foam 24-30
Polystyrene Foam 33-35
Fiberglass 38-42
Lofted Polyester Apparel Insulation 38-47

Aerogels will not absorb water yet are breathable

  • Aerogel is durably water repellent, even at high temperature
  • Hydrophobicity allows Aerogel to maintain thermal conductivity properties in wet conditions
Aerogel is super-hydrophobic, yet also… …water vapor permeable
Water droplet with contact angle >150° Steam penetrates aerogel from kettle underneath

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Insulates better than air

Why Aerogel is better insulator than air?

  • Collisions with pore walls more frequent than with other molecules of gas (mean free path is much shorter than at 1 atm of gas outside the solid)
  • Aerogel blankets have TC about 12-13 mW/m-K at 100 °F
  • Still (“quiescent”) air à 26 mW/m-K at 100 °F; highly sensitive to air gap size because of rapid onset of convection

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Guinness records

Aerogels have extreme structures and extreme physical properties:

  • Aerogels have extremely low thermal conductivity of 12-13 mW/m-K at 100 °F
  • Aerogels are exceptional reflectors of audible sound, making excellent barrier materials; aerogels have very low sound velocity through structure (~100 m/s)
  • Aerogels can be exotic energy absorbers, showing capability to capture high velocity dust particles in space that would penetrate thick steel
  • High internal surface areas (up to 1500 m2/g)
  • Ultra-low refractive index values for a solid (1.025), approaching that for air

Ultra- Silica Aerogel holds six world records for physical properties:

  • the highest thermal insulation value,
  • the lowest density,
  • the highest specific surface area,
  • the lowest refractive index,
  • the lowest speed of sound
  • the lowest dielectric constant of any solid.

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Video demos

Watch the demonstrations of some amazing aerogel properties here:

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