Ⅰ. What are the product forms of aerogels?
At present, the main forms of aerogel products include aerogel sheets, aerogel plates, aerogel films, aerogel papers, aerogel particles, aerogel powders, aerogel coatings, and aerogel special-shaped parts. These products are all made of aerogel and corresponding fiber materials, and the basic technology is similar, but the application fields and performance of the products vary greatly.
1. Aerogel sheets: It is a large-scale, widely used, technologically mature, and highly insulating aerogel product. The main characteristics of aerogel sheets are low thermal conductivity, good insulation effect, high hydrophobicity, and less powder loss. It is widely used in aerospace and military industries, petrochemicals, metallurgy and building materials, rail transit, high-speed trains, nuclear power, ships, power batteries, pipeline and tank bodies, refrigerators and cold storage, etc., for insulation and heat preservation applications.
2. Aerogel films, papers, and special-shaped parts: They are mainly used in some special fields. For example, aerogel films are mainly used in the clothing and footwear industry, while aerogel paper (thin sheet) is mainly used for battery insulation and some fields with very small space, very thin pipe diameters, or those requiring winding construction, and aerogel special-shaped parts are mainly used in military manufacturing for detachable insulation sleeves.
3. Aerogel plates: The main difference between aerogel plates and felt is the hardness. Felt is flexible and can be curled, while plates have a certain rigidity and are not prone to bending. The main application of this plate is for the insulation of large equipment and future building energy-saving exterior and interior walls.
4. Aerogel particles: Currently, the main application of aerogel particles is to fill them in PC boards or hollow glass as a light-transmitting and heat-insulating board. Although there is some market application, the scale is relatively small.
5. Aerogel powders: The industrial history of aerogel began with powders, but unfortunately, so far, no substantive batch applications of aerogel powders have been discovered.
6. Aerogel coatings: The coatings in traditional insulation materials are very important products, playing an irreplaceable role in many fields. The thermal conductivity of aerogel coatings is lower than that of traditional coatings, and they have good insulation effect and certain hydrophobic effect.
II. Can aerogel be used for clothes?
Aerogel can be made into textiles, clothing insulation, or naval diving suits, astronaut suits, etc.
Aerogel is a solid gel material with a porous network structure, and its internal pores are filled with air. Professor Kistler from Stanford University in the United States first obtained silica aerogel through the sol-gel method under supercritical drying conditions using sodium silicate.
There are many types of aerogels, among which SiO2 aerogel is the most common, presenting a semi-transparent light blue color, with extremely light mass similar to "solid smoke". As a typical porous material, most of the space inside SiO2 aerogel is filled with air (or other gases), and its skeleton volume only accounts for 0.15% to 15% of the total volume.
The average pore diameter of aerogel is approximately 25 nm, and air molecules (free path 50-70 nm) cannot freely move within it; in addition, there are many "dead-end" holes of different sizes in the internal skeleton of aerogel, which increases the path for heat transfer in the solid, so aerogel is a poor thermal conductor.
III. Applications of aerogel materials
1. Insulation materials (thermal insulators)
(1) In pipeline insulation, storage and transportation of volatile or flammable substances. The most widespread application of aerogel materials is in furnace pipeline insulation, thermal power plant pipeline insulation, and liquefied natural gas storage tanks.
(2) In textiles and clothing insulation. In the early 20th century, aerogel blankets began to appear. Aspen Company in the United States once prepared a blanket-like aerogel product called Spacelofl by combining aerogel with fabric; around 2010, Hugo Company successfully launched an aerogel jacket and successfully launched it on the market; mountain climbers also gave high praise for aerogel shoe insoles and sleeping bags (inner lining materials). (3) In areas such as building materials and refrigerators. Aerogel materials can be used on the roofs or glass of buildings to provide insulation. The thermal conductivity of aerogel glass is extremely low, which can achieve excellent energy-saving effects. Moreover, the current fluorine-based refrigerators or polyurethane foam plastics produce chemicals that damage the ozone layer, so the use of aerogel is also more environmentally friendly.
2. Aerospace field
Aerogel materials are also widely used in the aerospace field, such as Mars probes, naval diving suits, and spacesuits.
3. Applications of aerogel in other fields
The adsorption property of aerogel can be used to manufacture gas masks or to treat pollution caused by oil leaks, and is also used in filters, fuel storage, and other aspects. In addition, aerogel can also be used as a template material.