With the gradual expansion of human activity space on the earth and the universe, the differences in the living environment faced by human beings have gradually emerged. How to keep warm and heat insulation is an important issue to ensure personal safety. As a nanoporous solid material, aerogel has the characteristics of low thermal conductivity, high porosity and low density. Its thermal insulation performance has been applied in many fields of the textile industry.
At present, my country's aerospace industry is developing rapidly, and the lunar exploration project and the Mars plan have appeared one by one in recent years. Space exploration is expanding from low-Earth orbit to deep space and the environment of alien planets. The unique vacuum and environmental characteristics of outer space and the way of heat conduction are very different from those of the earth. In the low-Earth orbit space and the lunar surface, the heat transfer mode is mainly radiation; on the surface of Mars and other planets, due to the protection of the planet's atmosphere, the heat transfer mode is mainly heat convection and heat conduction. The temperature difference between day and night on the lunar surface exceeds 280°C; the temperature of Mars in summer is -83--33°C, and the temperature in winter is as low as -123°C. Therefore, space suits need to have good thermal resistance and thermal radiation resistance to maintain astronauts in a relatively stable and comfortable temperature environment. In the 1990s, NASA took the lead in applying aerogel to the aerospace field. Adding an 18mm thick aerogel layer to the spacesuit can help astronauts withstand high temperatures of 1300°C and minus 130°C. Ultra-low temperature.
In addition, aerogel is also used in fire protection. A fire suit is a multi-layer fabric system that includes a fire retardant layer, a waterproof breathable layer, and an insulating layer. The thermal insulation layer can effectively block the transfer of external heat to the human body. Commonly used thermal insulation materials include flame retardant cotton fibers, phase change materials, and shape memory materials. As the best protective thermal insulation material, aerogel can make fire suits withstand temperatures as high as 620°C, and the back temperature of fire suits is reduced by 100°C compared with the original, which significantly improves the thermal protection performance of fire suits. Moreover, the weight of aerogel is only about 10% of the protective insulating material of conventional fire suits, which is more comfortable to wear and more convenient for fire fighting.
In the civilian field, aerogel composite materials combine light, waterproof, windproof, warm, breathable and other properties, and are widely used in clothing such as jackets, cold-proof clothing, hiking shoes and even insoles. The thermal conductivity of commonly used clothing materials is relatively low. For example, the thermal conductivity of down is 5.930W/(㎡•K), wool is 6.986W/(㎡•K), and cotton is 9.717 W/(㎡•K). Air convection is the most effective way to prevent heat loss. The thermal conductivity of the aerogel composite material is 3.77 W/(㎡•K), and only 2mm thick aerogel composite material (74.03% heat preservation rate) can be equivalent to 40mm thick down fiber (78.12% heat preservation rate) The thermal insulation effect, in the cold winter, bid farewell to the bloated jacket, which is both warm and fashionable.
Advantages of aerogel insulation materials
Cold-proof and warm-keeping: low thermal conductivity, thermal conductivity at room temperature is only 0.013W/(m·K), and cold-proof performance is more than 5 times that of down;
Strong air permeability: low density, high porosity of more than 90%, nano-porous material, moisture-wicking and breathable, more comfortable to wear;
Extremely thin and light: lined with 6mm thick aerogel composite material, it can ensure warmth at an ambient temperature of -8°C;
Waterproof and hydrophobic: The hydrophobicity rate is N98%, the overall hydrophobicity, effectively preventing the penetration of liquid water, suitable for outdoor complex environment operations;
Flame retardant and fireproof: A1 class fireproof and non-combustible grade, can withstand high temperature burning at 620℃;
Green and environmental protection: Nano water-based material, no VOC (volatile organic compounds), non-toxic and harmless to human body.