Aerogel is a new type of amorphous solid material, which is composed of nanometer sized particles and air as dispersion medium. Different from the wet gel with solvent as the dispersion medium, the aerogel is a lightweight nano porous material prepared by replacing the solvent in the original skeleton with air. It is different from the dry gel obtained by the conventional sol gel method. Because of its translucent color and ultra light weight, the aerogel is sometimes called solid smoke or frozen smoke. Due to the super thermal insulation properties of aerogels with nano pores, aerogels have a wide range of potential applications in the field of building energy conservation. However, when applied in the field of construction, the cost of synthesizing these super materials is too high. Only by reducing the production cost of these super materials can this new type of functional material be widely used.
Aeroneneneba gel, a porous lightweight material, has been discovered as early as 70 years ago. In 1931, Kistler S. of California Pacific University used supercritical drying to remove water from the hydrogel, and obtained the first non shrinking aerogel material. During the development and evolution of these years, many potential excellent properties of aerogel materials have been developed. Now what we call SiO2 aerogel is a translucent material composed of nano-SiO2 skeleton. Its porosity is as high as 99%, density is 0.05~0.2g/cm3, gel size is less than 50nm, and pore diameter is less than the average free path of molecules The thermal conductivity is 0.03~0.05W/m · K at normal temperature.
The application of SiO2 aerogel in construction is still a blank in China, and the current research is mainly focused on the development of high value-added application products, such as aerospace, drug carriers, etc. In foreign countries, since 2000, there has been some research and application of aerogel materials for building. At present, the main research directions are gel energy-saving windows, gel coatings, new aerogel plates and roof solar collectors.
