Silica gel has excellent thermal insulation properties, low density, low sound transmission rate and large surface area due to its special structure. After years of research and analysis, silica gel has shown great potential for application. 
Introduction to Silica Gel 
When preparing silica gel, it is advisable to make full use of sodium silicate. Sodium silicate is a soluble alkali metal silicate formed by silicon dioxide and alkali metal oxides, also known as sodium silicate hydrate. Sodium silicate can be classified into two types based on the type of alkali metal, namely potassium sodium silicate and sodium sodium silicate. The basic direction for preparing silica aerogels at present is to utilize low-cost and inexpensive silicon sources. Many domestic researchers use low-priced sodium silicate as the raw material when preparing silica aerogels. However, during the actual preparation of silica aerogels, due to the presence of impurities such as sodium chloride, it will to some extent affect the purity of the preparation. At this time, solvents should be used for replacement and washing, and the preparation time should be appropriately increased. 
The characteristics and applications of silica gel for thermal insulation and heat preservation 
The typical application of silica gel is for thermal insulation. Silica aerogel has a thermal conductivity of less than 0.02/(m·k), even lower than that of air. Silica aerogel is currently the best material for thermal insulation in practical applications, suitable for use in defense, industry, and research fields, especially in navigation and aerospace fields. It can also be applied in pipeline insulation, refrigerator insulation, clothing insulation, and glass for thermal insulation. 
Catalyst carrier and catalyst 
With the continuous development and research of silica gels, the thermal conductivity of silica aerogels can be continuously improved, their strength can be enhanced, and they can be ensured to be applicable in catalyst carriers and catalysts. For instance, the organic fusion of SiO2 and TO2 or the co-precipitation of Si and T metal alkoxide salts can result in TO2-SiO2 aerogels. These aerogels can effectively enhance the adsorption performance, specific surface area, and other capabilities of silica aerogels. 
Acoustic delay 
Because the silica gel has a rather unique porous nanostructure, sound can be transmitted within the pores. At this time, there will be significant energy loss, which will reduce the amplitude of the sound wave and slow down the sound speed. Moreover, in solid materials, aerogel has a relatively low propagation rate and a relatively large impedance propagation range. Based on this, the silica aerogel prepared has the advantages of corrosion resistance, anti-aging, and high-temperature resistance. Currently, silica aerogel can be applied in ultrasonic detectors, acoustic instruments, and soundproof windows. 
Integrated Circuit


The key factor affecting the operating speed is the substrate material of the integrated circuit. Alumina ceramics is currently the substrate material in use, which has a relatively high dielectric constant. In the research, attempts have been made to replace the above substrate material with polymer materials, but this will lead to the occurrence of thermal stress. Silica aerogel has a relatively low dielectric constant, a high breakdown voltage, a close expansion coefficient to silicon materials, and good thermal stability. It can be applied in integrated circuits, thereby achieving the reduction of energy consumption, crosstalk, interconnect delay, and it is highly likely to triple the operating efficiency. However, at present, effective solutions need to be found for the problems of membrane cracking, leakage current, and fluidity. 2 
This entry contributor is: 
Cheng Peng - Associate Professor - Southwest University 
Source: Science Popularization China