Aerogel is a solid that is up to 99.8% air — one of the lightest solid materials ever made and the best thermal insulator known. It is made by removing the liquid from a gel without letting the gel's nano-scale structure collapse, leaving a rigid sponge of pores so small (2–50 nanometres) that heat can barely pass through. That is why a 10 mm aerogel blanket insulates as well as 20–25 mm of mineral wool.
What is aerogel?
Aerogel is not a gel — it is a dry, solid, open-cell material. Chemists start with a "wet gel" (like jelly, a solid network filled with liquid) and replace the liquid with air. In ordinary drying the pores collapse; aerogel is dried in a way that keeps the network intact. The result is a translucent, often bluish solid nicknamed "frozen smoke" or "blue smoke". The blue tint comes from the tiny pores scattering light, the same reason the sky looks blue.
What is aerogel made of?
Most aerogel is made of silica (silicon dioxide, SiO₂) — the same compound as glass and sand, in an amorphous (non-crystalline) form. Aerogels can also be made from carbon, alumina, metal oxides, polymers and graphene. For insulation, silica aerogel is reinforced with glass or ceramic fibres to make flexible blankets that can be cut and wrapped.
How is aerogel made?
- Sol-gel: a silica precursor (such as a silicate or alkoxysilane) reacts in a solvent and links into a wet gel.
- Ageing and solvent exchange: the gel is strengthened and its water replaced with a solvent such as ethanol.
- Hydrophobic treatment: the surface is made water-repellent (essential for insulation).
- Drying: supercritical CO₂ drying (or ambient-pressure drying) removes the liquid without collapsing the pores.
- Composite forming: for blankets, the gel is formed inside a fibre mat before drying.
Aerogel was invented in 1931 by Samuel Kistler in the USA. It stayed a laboratory curiosity until fibre-reinforced aerogel blankets were commercialised in the early 2000s.
Aerogel properties
| Property | Silica aerogel |
|---|---|
| Air content (porosity) | Up to 99.8% |
| Density | Monolith ~3–150 kg/m³; insulation blanket 150–220 kg/m³ |
| Thermal conductivity | ~0.013 W/m·K (monolith); 0.018 W/m·K (WedGel blanket at 25 °C) |
| Pore size | 2–50 nm |
| Surface area | 500–1,000 m²/g |
| Service temperature | −200 °C to +650 °C (blanket grades) |
| Water | Hydrophobic grades repel liquid water |
| Fire | Silica aerogel is inorganic and does not burn |
Types of aerogel
- Silica aerogel — the most common; used in insulation blankets, granules and powder. See silica aerogel blanket price per sq ft.
- Carbon aerogel — electrically conductive; used in supercapacitors and batteries.
- Alumina and metal-oxide aerogels — high-temperature catalysts and insulation.
- Polymer (polyimide) aerogels — flexible films for aerospace.
- Graphene aerogel — among the lightest materials ever made; research and niche uses.
Uses of aerogel
- Space: NASA used aerogel to insulate Mars rovers and, on the Stardust mission, to capture comet dust.
- Industry: steam, hot-oil and LNG pipelines, refineries, furnaces, boilers and cryogenic tanks.
- Buildings: thin internal wall insulation, roofs, thermal-bridge fixes, daylighting panels.
- Cold chain: cold rooms, reefer containers and insulated boxes.
- EV batteries: thin barriers that slow thermal runaway between cells.
- Clothing and gear: insoles, gloves and jackets for extreme cold.
- Coatings and plasters: aerogel powder adds insulation to paints and renders.
Aerogel vs other insulation
| Material | λ (W/m·K) | Thickness for the same insulation |
|---|---|---|
| Aerogel blanket | 0.018 | 10 mm |
| PUF / PIR | 0.022–0.028 | 12–16 mm |
| XPS | 0.029–0.035 | 16–19 mm |
| Mineral wool / glass wool | 0.035–0.045 | 19–25 mm |
| Calcium silicate | 0.055–0.065 | 31–36 mm |
Is aerogel safe?
Yes. Insulation aerogel is amorphous silica, which is not the crystalline silica linked to lung disease. Cutting blankets releases fine dust that can irritate skin, eyes and the throat, so wear gloves, glasses and a dust mask during installation.
Aerogel price in India
Aerogel insulation blankets cost about ₹1,350–3,850 per m² (₹125–358 per sq ft) depending on thickness and temperature grade. See the full aerogel blanket price table. The online price on this page is for 10 g of aerogel (₹4,320 per kg).
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