There are many types of aerogels, including silicon-based, carbon-based, sulfur-based, metal oxide-based, metal-based, etc. Among them, SiO2 aerogel is a type of aerogel that is widely used and has mature industrialization. The industrial development of aerogels at home and abroad mostly revolves around the thermal insulation application of silica aerogels.
Silica aerogel was successfully prepared using supercritical drying method, so aerogel is defined as: the material obtained by supercritical drying of wet gel, which is called aerogel
The preparation of aerogels usually consists of a sol-gel process and supercritical drying. In the sol-gel process, by controlling the hydrolysis and polycondensation reaction conditions of the solution, nanoclusters with different structures are formed in the solution. The clusters adhere to each other to form a gel, and around the solid skeleton of the gel Filled with liquid reagents remaining after a chemical reaction. In order to prevent the surface tension in the micropores from causing damage to the material structure during the drying process of the gel, a supercritical drying process is used. The gel is placed in a pressure vessel to heat and increase the pressure, causing the liquid in the gel to undergo a phase change. In a supercritical fluid, the gas-liquid interface disappears and the surface tension no longer exists. At this time, the supercritical fluid is released from the pressure vessel, and a porous, disordered, low-density gas with a nanoscale continuous network structure can be obtained. gel material.
As an efficient thermal insulation and energy-saving material, aerogel is a national basic strategic cutting-edge new material, which is of great strategic significance for reducing carbon emissions and achieving the “double carbon” goal. Several documents such as the “Carbon Peak Action Plan before 2030” clearly propose to accelerate the research and development and application of airgel materials.
