Aerogel is a new generation of highly efficient and energy-saving insulation material. Aerogel is a solid material with a nano-porous network structure and filled with gaseous dispersed media in its pores. It is the lightest solid in the world. Due to its unique structure, aerogel exhibits excellent performance in multiple fields such as thermology, acoustics, optics, electricity, and mechanics. Currently, the commercial applications of aerogel mainly focus on its efficient heat-blocking ability, and it is used downstream in various fields such as petrochemicals, thermal pipelines, lithium batteries, building materials, outdoor clothing, aerospace, and military industries. 
The heat-blocking principle of aerogel is due to its unique structure, which eliminates convective effects, has an infinite number of shielding plate effects, and has an infinitely long path effect. The thermal conductivity of aerogel ranges from 0.012 to 0.024 W/(m·K), which is 2 to 3 orders of magnitude lower than that of traditional insulation materials. The principle of its insulation lies in the uniform and dense nano-pores and multi-level fractal pore channel microstructure, which can effectively prevent air convection, reduce heat radiation and heat conduction: 
1) No convection effect: The pores of the aerogel are at the nanometer scale, and the internal air loses its ability to freely flow. 
2) Infinite number of shielding plate effect: Nanometer-sized pores, with countless pore walls, minimizing heat transfer through radiation; 
3) Infinite length path effect: Heat conduction occurs along the pore walls, and the nanoscale pore walls are infinitely long. 
Compared with traditional insulation materials, the insulation performance of silica aerogel insulation board is 2 to 8 times that of traditional materials. Therefore, with the same level of insulation effect, the amount of aerogel used is less. Taking pipes as an example, for a pipe with a diameter of 150mm to achieve the same insulation effect, the thicknesses of the insulation materials - expanded perlite, calcium silicate, rock wool, and aerogel board - used correspondingly are 90mm, 76mm, 64mm, and 20mm respectively. According to the calculation of Sinopec Tahe Refinery, after converting the atmospheric pressure coking unit from traditional insulation materials to the "silica aerogel insulation felt + single-sided aluminum foil glass fiber cloth insulation material" combined insulation method, the heat loss was reduced by 34.7%, and the insulation layer thickness was reduced by more than 50% compared to traditional insulation materials. 
Core advantage of aerogel material - insulation
In addition, aerogel has the advantage of a longer service life. Its service life is approximately 4 times that of traditional insulation materials. Traditional insulation materials such as rock wool and polyurethane tend to absorb water during long-term use. This not only affects the insulation effect but also causes the insulation material to be unevenly distributed due to the force of gravity after absorbing water. Especially in the application scenario of pipeline insulation, it is prone to cause the insulation material to accumulate at the bottom of the pipeline, ultimately affecting the service life. Aerogel, on the other hand, has excellent waterproof performance. Its water repellency rate is over 99%. It can maintain a stable structure and insulation effect during long-term use. 
The currently available commercial aerogels are usually composite materials with various forms. Aerogels have disadvantages such as low strength and poor toughness. Therefore, to improve their strength and toughness, reinforcing materials such as particles and fibers need to be added. Additionally, light-blocking agents such as carbon black and ceramic fibers can be added to enhance the radiation shielding ability. Therefore, the currently available aerogel products are often made by combining aerogel materials with base materials. According to the form of the product, aerogel products can be classified as aerogel mats, aerogel papers, aerogel films, aerogel sheets, aerogel powders, aerogel pastes, and aerogel coatings, etc. 
The lowest density of the solid is less than 1.5 mg/mL. 
2. The smallest aperture is 1 to 100 nanometers. 
3. The highest porosity rate is over 99.9% 
4. The highest specific surface area is 200 - 1000 m2/g 
5. The lowest thermal conductivity: It can reach 0.013 W/(K·m) at normal temperature and pressure. 
6. Excellent fire resistance performance: Fire resistance rating A1, smoke emission rating AQ1 
7. Superhydrophobic property: Water absorption rate > 99% 
8. The lowest sound propagation speed is less than 70 meters per second. 
9. The lowest dielectric constant is less than 1.003. 
10. The lowest refractive index is less than 1.0003. 
There are various types of aerogel materials, among which SiO2 aerogel has the most mature commercial application. Aerogels can be classified into seven categories based on their precursors: oxides, carbides, polymers, biomass, semiconductors, non-oxides, and metals. With numerous different precursors, various properties of aerogels can be achieved, greatly enriching the diversity of aerogel varieties and expanding their application scope. Currently, SiO2 aerogel has the most mature application in the market, with a global proportion of silica aerogel reaching as high as 69% in 2019. 
The precursor of silica aerogel can be divided into organic silicon sources and inorganic silicon sources. The commonly used organic silicon sources are functional silanes such as methyl silicate and ethyl silicate. The inorganic silicon sources include tetra-chlorosilane and water glass, etc. Compared with inorganic silicon sources, organic silicon sources are more expensive in terms of price, but they have higher purity and good process adaptability, and can be adapted to supercritical drying and atmospheric pressure drying. Although the price of inorganic silicon source water glass is lower, it contains more impurities and is currently mainly used in atmospheric pressure drying. 
Core advantage of aerogel material - insulation
The aerogel products are made by combining nano-aerogel with base materials such as glass fibers and ceramic fibers. This combination perfectly integrates the excellent properties of aerogel with flexible base materials, maximizing the retention of aerogel's lightweight and heat insulation characteristics, while also endowing aerogel with flexibility and toughness. They possess additional features such as extremely long service life, super strong heat insulation performance, ultra-high fire resistance, and outstanding mechanical properties. Aerogel products are widely used in fields such as military and aerospace, thermal pipeline networks, petrochemicals, new energy vehicles, battery power supplies, rail transit, consumer electronics, and textiles. 
Ceramic fiber base aerogel insulation pad (with a temperature resistance of 1050℃) 
The SiO2 aerogel composite material with ceramic fibers as the base material is fabricated through the process of embedding in a silicone frame and then coating. 
2. Pre-oxygenated silicon-based aerogel insulation pad (with a temperature resistance of 450℃) 
A SiO2 aerogel composite material based on pre-oxidized fibers. It is fabricated through the process of embedding in a silicone frame and coating. It can also be directly applied by spraying a flame-retardant adhesive. 
3. Glass fiber base aerogel insulation pad (with a temperature resistance of 650℃) 
The SiO2-glass fiber composite material is fabricated by embedding it in a silicone frame and then applying a coating.