Aerogel powder is a lightweight porous inorganic functional material composed of nano-scale three-dimensional network skeleton and a large number of air pores, known as "frozen smoke", and it is also the core form of aerogel materials for industrial application. Compared with bulk aerogel, powder form is easier to disperse and compound for processing, with porosity as high as 90%–99% and specific surface area up to 500–1200m²/g. It has multiple advantages such as ultra-low thermal conductivity, low density, high temperature resistance, hydrophobicity and flame retardancy, making it a key material in high-end thermal insulation, adsorption and catalysis fields. Its preparation process and structure control directly determine product performance and application boundaries.
The mainstream preparation of aerogel powder centers on sol-gel method, combined with drying process to stabilize the nanopore structure. The core raw materials are mostly silicon sources such as ethyl orthosilicate and water glass, balancing cost and performance. The complete preparation process is divided into four steps: firstly, the silicon source undergoes hydrolysis reaction in water and alcohol solvent under acid-base two-step catalysis to generate active silanol monomers; then the monomers rapidly polycondense to form uniform wet gel, with continuous nano-pores formed inside the gel; next, solvent replacement is used to remove water in the pores to avoid pore collapse during subsequent drying; finally, shaping is carried out through drying process, divided into two technical routes: supercritical drying and atmospheric drying. Supercritical drying breaks liquid surface tension via high temperature and pressure, with complete pore structure, but it requires large equipment investment, high energy consumption and cost; atmospheric drying greatly reduces production cost through surface hydrophobic modification and gradient heating drying, suitable for large-scale production, becoming the current industrial mainstream route, and product performance can meet the needs of most scenarios.
The unique nanoporous structure endows aerogel powder with irreplaceable comprehensive properties. Its thermal conductivity is as low as 0.012–0.024W/(m·K), far lower than traditional rock wool and polystyrene board, with thermal insulation efficiency 3–5 times that of conventional thermal insulation materials; density is only 0.05–0.2g/cm³, and the lightweight feature greatly reduces substrate load; after hydrophobic modification, water absorption rate is lower than 5%, maintaining stable performance for a long time in high-humidity environments; meanwhile, the inorganic silicon skeleton gives it Class A non-combustible characteristics, with high temperature resistance up to 600℃, suitable for extreme working conditions.
Current process upgrades focus on greening and precise control. By optimizing catalyst ratio, shortening reaction cycle and recycling organic solvents, low-VOC and low-energy consumption production is realized; meanwhile, precise control of pore size and particle size distribution improves powder dispersibility and compatibility, solving the pain points of easy agglomeration and uneven compounding of traditional powders. With the continuous iteration of atmospheric drying technology, aerogel powder is moving from a high-end niche material to a new stage of large-scale, low-cost and high-performance industrialization, providing core material support for the upgrading of downstream fields.