Analysis Of Five Characteristics Of Silica Aerogels
Silica aerogel is light nano porous excellent thermal insulation properties of an amorphous solid material, its porosity is up to 80-99.8%, the typical size of holes is 1-100 nm, the surface area is 200-1000 m2/g, and the density is as low as 3 kg/m3, room temperature thermal conductivity can be as low as 0.012 W/ (M·K). It is because of these characteristics that the aerogel materials have great potential in the field of heat, acoustics, optics, microelectronics and particle detection.
Properties of silica aerogel
1. Heat insulation
Silica aerogel material has very low thermal conductivity, which can reach 0.013-0.016W/ (M. K), which is lower than that of static air (0.024W/ (M. K)). The thermal conductivity of silica aerogel is 2-3 orders of magnitude lower than that of the corresponding inorganic insulation material.
The thermal conductivity is 0.043W/ (M. K) even at the temperature of 800 C. No decomposition at high temperature, no harmful gas release, is a green environmental material. SiO2 silicone aerogels are combined with various heat-resistant fibers and can be made into various forms of thermal insulation. It can be widely used in industry, construction, pipeline, automobile, space and other fields.
2, Sound insulation
It is also an ideal acoustic delay or high temperature sound insulation material because of the low sound speed characteristic of the silicon aerogel. The acoustic impedance of the material has a larger variable range (103-107 kg/m2. S). It is an ideal acoustic impedance coupling material for ultrasonic detector.
Preliminary experimental results show that the silica aerogel with a density of about 300 kg/m3 can enhance the sound intensity by 30 dB. If we use silica aerogel with density gradient, we can get higher sound intensity gain.
3, Nonlinear optical properties
Because quantum dot structure formation of silicon aerogel nano network, chemical vapor infiltration of Si doped and C60 doped solution method. The results showed that the doping agent is present in the form of nano grain, and observed a strong visible light emission, and provide strong evidence for the quantum confinement effect of porous silicon luminescence. By using the structure of the silicon aerogel and the nonlinear optical effect of C60, a new type of laser protective mirror can be developed.
4, Filtration and catalytic properties
Nanostructured aerogels can also be used as new gas filtration. Unlike other materials, the aerogel is different from other materials. It has a uniform pore size and a high porosity. It is an efficient gas filtration material. Because the material is especially large than the table. Aerogels have a broad application prospect as a carrier of new catalysts or catalysts.
5, Refractive index tunability
Refractive index of silica aerogels were close to L, but also on the infrared and visible extinction coefficient of more than 100, can effectively through the visible part of the sun, and the infrared part of the barrier, has become an ideal transparent insulation material, has been widely used in solar energy utilization and building energy saving.