In the 250 issue of Science, a top authoritative international academic journal, ten new materials that can change the world are listed. Among these new materials, one material occupies the first place among the ten new materials because it holds a number of world records. The material is only slightly heavier than the equivalent weight of air, but it can resist temperatures of 1,400 degrees Celsius, higher than the melting point of most metals. Scientists around the world have been fascinated by its unique properties. It is called aerogel.
Aerogel is a kind of highly dispersed solid material which is formed by colloid particles coalessing with each other to form a nanoporous network structure and filled with gaseous dispersing medium in the pores. With low thermal conductivity, low density, low dielectric constant, low impedance, high porosity, high specific surface area and other characteristics, in the thermal, electricity, acoustics, mechanics, optics and other fields show excellent performance, in aerospace, aviation, transportation, petroleum, communication, central heating and cooling, construction, metallurgy, electronics, environmental protection and other fields have a wide range of application prospects.
Silica gel is by far the best insulation material that has been commercially produced. SiO2 gel material has the characteristics of low density and low thermal conductivity, which can effectively inhibit heat conduction. Its average aperture size is 50 nm, lower than the average free path of air molecules, which can effectively inhibit air heat convection heat transfer. In addition, the "infinite" void walls of the silica gel are equivalent to the reflective and refracting surfaces of the radiation, and the combination of special reflective materials can minimize the thermal radiation. In conclusion, silica gel material can effectively inhibit the combined action of heat conduction, heat convection and heat radiation, and almost block all the ways of heat transfer, so it is a kind of heat insulation material with great application value.
