Aerogels Still Remain To Be Improved

Silica Aerogel in Insulation is an extremely light material with a high porosity and very low density. It is also known for its remarkable physical properties and is a great alternative to traditional thermal insulation materials due to its superior compressive strength. It has a wide range of applications in aerospace, from acoustical and thermal isolation to kinetic shock absorbers. Its unique structure consists of a series of interconnected silica particles tortuously entangled together in a fractal network. This structure allows for thermal transport while preventing heat dispersal and loss.

The skeleton-like structure of the aerogel makes it inapt for load bearing applications, so researchers have been working to strengthen these nanomaterials by cross-linking their pore structures. The resulting skeletons are stronger and more durable, and have higher elastic moduli than the original silica gels.

However, the mechanical properties of aerogels still remain to be improved. The reason for this lies in their brittle nature caused by the weak connections between the particles within the pearl-necklace-like fractal network. This has been mitigated by the development of methods to characterize the material mechanically and to understand its behavior under different conditions. Various techniques such as ultrasonic techniques, three-point bending and uniaxial compression have been used to evaluate the strength of these materials. More recently, scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been employed to visualize the local elasticity of these materials.

It is possible to make silica aerogel more robust without jeopardizing its unique properties. One way is to replace the alcohol in the synthesis process with liquid carbon dioxide. This allows the synthesis to occur at lower temperatures and pressures, which reduces the risk of hazard. Another route involves modifying the coprecursor, which is a precursor to the silicic acid, to create a more stable matrix that prevents drastic gel shrinkage during drying.

Aerogels are being incorporated into cosmochemical systems to capture extraterrestrial samples. These materials have a great potential for separating and analyzing extraterrestrial particles such as ice, gases, organic compounds and other non-organic components. They can also be employed to trap hypervelocity cosmic dust.

Despite their exceptional physicochemical properties, the biggest obstacle to integrating aerogel into aerospace is its high cost. It is hoped that the benefits of using this lightweight material will outweigh the initial investment. Aerogels can be used in the form of panels or sheets to provide thermal and acoustic protection for small satellites, spacecrafts and planetary vehicles.

Among other applications, aerogels can help to reduce the take-off weight of aircraft and thus save fuel. According to American Airlines, saving just a million gallons of jet fuel equates to $422 million in savings every year. However, it is important to note that silica aerogel must be combined with other materials such as metals and composites in order to be used in aerospace. In addition, the aerogel must be able to withstand a range of environmental conditions such as high temperature and pressure. This will require the development of a new synthesis method and the incorporation of polymers to strengthen the skeletal structure of the aerogel.