Silica Aerogel - Lightweight, Fireproof, Soundproof and Waterproof

Silica Aerogel has attracted the interest of many researchers because of its remarkable properties of being lightweight, fireproof, soundproof and waterproof. Its applications can be found in a variety of fields including construction and aerospace. Silica aerogel is a gel-like material with a high bulk density of 0.087 + 0.004 g/cm3. It has very low thermal conductivity, high permeability and porosity with a maximum vapor pressure of 0.2 kPa at 0°C.

The synthesis of Silica Aerogel in Insulation is accomplished by calcination at a very high temperature and subsequent drying in air. This process is a laborious one, and the bulk density of the aerogel depends on the concentration of tetraethyl orthosilicate (TEOS) in the calcination solution.

In the aerospace industry, aerogel is mainly used as a hypervelocity particle capture material. It is also utilized in the thermal insulation of spacecrafts and satellites. The insulating capacity of this material can significantly reduce the energy consumption in aerospace vehicles by improving their efficiency. In addition, it can protect sensitive instruments from the extreme environmental conditions in outer space.

In 1997, silica aerogel was used to encapsulate the primary battery pack of the Alpha Particle X-Ray Spectrometer on the Mars Exploration Rover, Sojourner. This was the first time that an insulating material had been used on an interplanetary vehicle to protect critical electronics from extremely cold temperatures. Silica aerogel is an excellent insulator with a low thermal conductivity, long life and good hydrophobicity. It is a great alternative to the traditional thermal insulation materials.

Silica aerogel is very versatile in its application, as it can be made into different forms and sizes. It can be sprayed as a thin insulative coating on unattainable surfaces or into compartments that need special protection. It can also be molded into rigid sheets or foam to provide fire and noise protection, or even serve as an acoustic absorber. Silica aerogel can be easily modified to change its appearance, from transparent to opaque. It is also possible to add carbon or mineral powders into the fractal network of an aerogel to make it more opaque.

Moreover, aerogel has an outstanding strength-to-weight ratio. Although it is brittle, it can be reinforced with fibers or other polymers to improve its mechanical strength. However, the main challenge for aerogel is its instability during processing and use. When it is mixed with other materials such as polymers, ceramics or metals, it tends to phase delaminate and lose its insulating properties.

To address this problem, scientists are currently researching methods to enhance the stability of silica aerogels. This will require a better understanding of the chemistry-structure-property relationship of these nanomaterials. In addition, they need to develop cost-effective manufacturing methods that will allow for the commercialization of aerogels.

In the near future, it is predicted that this material will be widely applied to a variety of aerospace and military applications. Especially in the aviation world, silica aerogel will be used as an efficient thermal and fire insulator, sound and vibration absorber, and water repellent for aircraft windows.