Frequently Asked Questions
Properties of Aerogels
Aerogels are a diverse class of ultralow density solids that combine multiple disparate and extreme materials properties into a single material envelope. Aerogel materials generally exhibit a high degree of porosity, high specific surface area, and superlative energy damping (thermal, acoustic, and impact) properties. The name aerogel may be misleading at first, as aerogels are dry, rigid or elastic foam-like materials—the name originates from the fact that aerogels are usually derived from wet gels, physically similar to edible gelation, in which the liquid component of the gel has been replaced by gas or a vacuum in a way that preserves the gel’s sparse solid, porous backbone.
Historically, the most researched type of aerogel has been the holographic-looking “blue” silica type. Today, aerogels of numerous different substances can be prepared, including:
- Silica, both hydrophilic (water-absorbing) and hydrophobic (water-repelling)
- Transition metal oxides, lanthanide oxides, actinide oxides, main group oxides, and mixed matrix oxides
- Polymers such as phenolics, polyureas, polyurethanes, polyimides, and polyamides
- Amorphous carbon, graphitic carbon, carbon nanotubes, and graphene
- Metal chalcogenides
- Quantum dots
- Metals and carbides
Each of these different types of aerogels provides unique properties, which can include electrical conductivity (carbon and metal aerogels), extreme (up to 80%) elastic return (nanotube and graphene aerogels), catalytic functions (various oxide and metal aerogels), photoluminescence (quantum dot and metal chalcogenide aerogels), water repulsion and oil sorption (hydrophobic silica and polymer aerogels), and more.
The insulating ability (or thermal conductivity) of an aerogel material depends on its composition, form factor, and density, as well as the temperature of its environment. Silica aerogel-based materials are typically used for insulating applications, although AirloysTM and polymer aerogels are beginning to be used as well. For a typical silica aerogel monolith with a density of ~100 mg/cc, the thermal conductivity is usually between 10-20 mW/m-K, or about 2-3 times more insulating per unit thickness than polyurethane foam (PUF) or Styrofoam® (expanded polystyrene). Composite aerogel blankets such as Aspen Aerogels’ Spaceloft® typically have a thermal conductivity of ~14-21 mW/m-K. Cabot Aerogel’s Lumira® aerogel particles used for daylighting applications similarly have a thermal conductivity of ~9-12 mW/m-K. Cabot Aerogel’s Thermal WrapTM blanket also used in daylighting and for low-dust applications has a thermal conductivity of ~23 mW/m-K. In general, the thermal conductivity of an aerogel decreases (that is, its insulating ability increases) as its density decreases. While aerogels are available in a wide range of densities as low as 1 mg/cc to ~500 mg/cc, in general only materials with densities in the range of 0.05-0.3 are practical for industrial applications. Generally speaking, the thermal conductivity of non-silica aerogels and Airloys is comparable to silica aerogels with the same density but may be higher or lower by up to 50% depending on composition.
The maximum operating temperature of an aerogel material depends heavily on its composition. Monolithic silica aerogels remain generally in tact until about 700°C, at which point they will begin to sinter (densify). At hotter temperatures, they will eventually melt. Composite aerogel blankets can be used at temperatures upwards of 1000°C. Note that hydrophobic (water-repelling) aerogels, including hydrophobic composite aerogel blankets, will lose their hydrophobic surface features at around 200°C. The maximum operating temperature of Airloys is series dependent. See Airloy.com for specific information about Airloy product temperature ratings.
First, not all aerogels are easy to break! Classic (or “legacy”) aerogels are notorious for exhibiting extremely high strength-to-weight ratios and being able (in principle) to hold thousands of times their weight in applied force. However, classic aerogels also typically exhibit low fracture toughness, that is, ability resistant propagation of a flaw in the material. As a result, it is possible for a classic aerogel block that’s 96% air by volume to hold a brick that’s thousands of times its weight, but only if the weight is placed on the monolith gently and there are no major flaws in the aerogel.
New strong aerogels such as Airloy™ strong aerogels from Aerogel Technologies are not only hundreds of times stronger and stiffer than classic aerogels but also fracture tough and mechanically robust. Airloys can be machined (drilled, tapped, turned, milled) and bent without breaking. Airloy strength, stiffness, and density depend are series dependent. See Airloy.com for specific information about Airloy product mechanical properties.
Aerogels are open-celled with pores less than 50 nm in diameter (typically 5-20 nm)—about 3,000 to 30,000 times smaller than the diameter of a hair.
Some aerogel materials are waterproof and some are not. Industrial aerogel materials such as Aerogel Technologies Airloy™ strong aerogels, Cabot Aerogel’s Lumira® aerogel particles, and Aspen Aerogels Spaceloft® aerogel composite blankets are specially formulated to be hydrophobic (water-repelling). Classic silica aerogels and other oxide-based aerogels are not natively waterproof but can be modified to not only be waterproof, but superhydrophobic.
The flexibility of an aerogel material depends on its composition and density. Classic silica, metal oxide, and carbon aerogels are not flexible and are usually very fragile. Airloy™ strong aerogels are usually flexible but very stiff (like bending a ballpoint pen). Specially formulated polymer and siilca aerogels are extremely flexible, ranging from cloth-like to marshmallow-like. Composite aerogel blankets such as Cabot Aerogel’s Thermal Wrap™ and Aspen Aerogels Spaceloft® are also extremely flexible and can be cut like other fabrics.
Aerogel materials vary in price depending on form factor and composition. Aerogel particles such as Cabot Aerogel’s Lumira® aerogel, used in the daylighting industry, as well as composite aerogel blankets such as Aspen Aerogels Spaceloft® and Cabot Aerogel’s Thermal Wrap™, used as insulation in buildings and oil pipelines, are produced on an industrial scale and cost-competitive with other high-performance thermal management technologies.
See our line of revolutionary AirloyTM Ultramaterials for applications requiring materials that combine the superinsulating properties of aerogels with strength and machinability.
In principle there is no limit to how large an aerogel material can be. Class monolithic aerogels typically require special high-pressure vessels to prepare and thus are often (but not always) limited to the inner dimensions of the pressure vessel available. Airloy™ strong aerogels from Aerogel Technologies are not restricted in this way. Aerogel composite blankets from Aspen Aerogels typically come in 150-cm-wide (59″-wide) rolls. Low-dust aerogel composite blankets from Cabot Aerogel typically come in 56-cm-wide (22″-wide) rolls.
Aerogel Technologies can accommodate production volumes large and small. Contact us to discuss your application needs.
Aerogel Technologies can produce specialty aerogel powders (e.g., hydrophilic silica, metal oxides, metals, carbon) for specific application needs. For high-performance silica aerogel additives, we recommend Cabot Aerogel’s Enova® aerogel line. Contact Cabot Aerogel for more information or feel free to contact us for assistance.
Different aerogel materials have different volume pricing schedules. Contact us to discuss your volume order needs.
Check out BuyAerogel.com, our online store for aerogel materials. There you’ll find several very affordable samples of various aerogel materials.
Classic monolithic aerogels are very difficult to machine. Never fear—Aerogel Technologies is the world leader in shape control of monolithic aerogels and can assist in producing specially-shaped and featured aerogel parts. Contact us to discuss a custom aerogel shape or machining project.
Alternatively, our AirloyTM Ultramaterials are aerogels made strong and machinable. Airloys can be easily drilled, tapped, turned, and milled just like other engineering materials. See Airloy.com for more information or order sample coupons today online at BuyAerogel.com.
Classic aerogel materials absorb liquids readily and are difficult to glue or adhere. For applications where adhesion of parts is required, we recommend AirloyTM strong aerogels.
Unfortunately,, even the lightest aerogels, even if evacuated or backfilled with helium, would be too heavy to float in air, especially if laminated to seal the outer edges of the monolith. However, a helium-backfilled aerogel can be made to float if dropped into an aquarium filled with xenon gas.
Environment, Health, and Safety
Aerogel materials are safe for the environment. Silica aerogel materials are similar to minerals found in nature (silicates are the most abundant minerals on Earth) and do not contain or emit harmful chemicals. Carbon aerogels are also similar to minerals found in nature and are chemically no different than charcoal. Polymer aerogels such as RF aerogels are generally not harmful however like other polymers and plastics care must be considered regarding biodegradability and methods of proper disposal.
Some aerogel materials are biodegradable and some are not. Biodegradability depends on the composition of the aerogel material.
One advantage of some industrial aerogel materials such as Cabot Aerogel’s Lumira® aerogel particles is that they can be reused and are generally harmless to the environment even if released.
Materials Safety Data Sheets for products manufactured by us, Cabot Aerogel, and Aspen Aerogels are available below and as links in product tiles for the relevant product on BuyAerogel.com.
Aerogel Technologies Products
Cabot Aerogel Products
Aspen Aerogels Products
Yes. Monolithic aerogels and AirloysTM produced by Aerogel Technologies are safe. Monolithic aerogels and Airloys produced by Aerogel Technologies are made with synthetic amorphous silica gel and/or polymers that have been shown to be safe for human health. Precipitated silica like that which comprises silica aerogels and used in some Airloys is widely used in personal care products such as lotions, cosmetics, and toothpastes. Silica aerogel materials manufactured by Aerogel Technologies do not contain crystalline silica or quartz and are not carcinogenic or mutagenic. As with other materials, though, we recommend wearing proper personal protective gear if you plan on grinding or otherwise mechanically processing monolithic aerogels or Airloys, or handle aerogel particles or insulating aerogel blankets extensively, to avoid inhalation of nuisance particles.
Contacting Aerogel Technologies
Aerogel Technologies can be reached toll-free in the United States at (888) X-AEROGEL ((888) 923-7643) or internationally at +1 (414) 944-0019.
Aerogel Technologies is located in Boston, MA.
Aerogel Technologies is the world leader in custom aerogel materials solutions. Our team of scientists and engineers will work with you to find a solution for your technology application. Contact us to begin the conversation.
The Dunlop® Aerogel tennis racquet incorporates silica aerogel powder into its handle in effort to dampen vibration transmitted from the ball to your wrist. Whether or not it actually works we’ll leave to the tennis pros to decide.