Thermal Insulation Property and Application Prospect of SiO2 Aerogel
SiO2 aerogel and pore structure in the micron and millimeter-scale porous material is different, the slim nanostructures make the material has very low thermal conductivity, with a large specific surface area, the light and sound scattering than the traditional porous The material is much smaller.
SiO2 aerogel heat transfer through the solid heat conduction, gas heat conduction and radiant heat conduction in three ways to complete.
The voids of the SiO2 aerogel and the curved path of the nanostructured network of fibers prevent the gaseous heat conduction of the air and the solid state heat conduction of the gel skeleton, respectively, and can also block thermal radiation by doping the infrared absorber. These three aspects work together, almost blocking all the heat transfer channels, so that SiO2 aerogel play a very good thermal insulation effect.
SiO2 aerogel thermal conductivity of 0.013W / (mK) below, far below the normal temperature static air thermal conductivity [0.025W / (mK)], and has a low density, waterproof and fire retardant, green, anti-acid Corrosion-resistant, not easy to aging, long life and other characteristics. Silica aerogel is the main component of SiO2, does not contain harmful substances, the resulting product is non-radioactive, compared with the traditional insulation materials more advantages. In addition, SiO2 aerogel has a higher acoustic impedance, the adsorption capacity of more than the traditional activated carbon adsorption materials, products with high added value, so called super insulation material.
However, the unique network structure of SiO2 aerogels, high porosity and low density and other characteristics also led to its fragile texture, and in high temperature environment, translucent SiO2 aerogel material is difficult to impedance radiation thermal conductivity Therefore, in many fields, SiO2 aerogel is more difficult to use alone as a heat insulation material, and it needs to be doped or modified to be used in combination with other heat insulation materials to achieve the ideal use effect.
Traditional aerogel preparation requires expensive raw materials and supercritical drying equipment, the high cost of production, which hinders the commercial production of aerogel the main reason. The latest development of aerogel manufacturing methods has been to use low cost raw materials such as water glass, and without supercritical drying, production costs dropped significantly, prompting more aerogel commercial applications.
Compared to other types of functional materials, SiO2 aerogel insulation material has significant advantages in the civil, chemical, construction, aerospace, medicine and other fields have a broad application prospects. Especially in the aerospace field, SiO2 aerogel insulation material as a super insulation material, to solve a series of aerospace technology problems, the development of aerospace technology is of great significance.