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
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:
