Aerogel particles are the most adaptable and widely used form in the aerogel material system. Different from aerogel powder and bulk aerogel, they have the advantages of regular particle size, good fluidity, less dust, easy filling and composite processing, making them the core carrier for large-scale engineering application of aerogel materials. As a kind of nanoporous inorganic particle, its porosity is as high as 90%-98%, particle size can be precisely controlled in the range of 0.5mm-10mm, and a continuous three-dimensional network silicon-oxygen skeleton is retained inside. It combines core properties such as ultra-low thermal conductivity, light weight, hydrophobicity, high temperature resistance and flame retardancy. The iteration of its preparation process and structural control directly determine the performance stability and industrial application feasibility of products.
The industrial preparation of aerogel particles takes sol-gel method as the core, combined with two key links of pelletizing shaping and efficient drying. The mainstream technical routes are divided into supercritical drying and atmospheric drying, and the industry has now fully transformed to atmospheric drying to achieve low-cost large-scale production. The core preparation process is divided into five steps: firstly, water glass or ethyl orthosilicate is selected as the silicon source, and hydrolysis and polycondensation reactions are completed under acid-base composite catalysis in water and ethanol mixed solvent to generate stable silica sol; then, the sol is shaped into uniform granular wet gel through spray granulation, extrusion pelletizing or gel crushing granulation process, with precise control of particle size and sphericity; next, multi-stage solvent replacement is carried out to remove water in the internal pores of the particles, replace with low surface tension organic solvent, and simultaneous hydrophobic modification is performed to prevent pore collapse during subsequent drying; then, the solvent in the pores is completely volatilized through gradient heating atmospheric drying to retain the complete nanoporous structure; finally, finished aerogel particles are obtained through screening and impurity removal.
Compared with powder, aerogel particles solve the pain points of large dust, easy agglomeration and difficult quantitative filling; compared with bulk aerogel, they have the advantages of flexible filling, adapting to complex cavities and convenient construction. Its core performance indicators are industry-leading, with thermal conductivity as low as 0.013-0.026W/(m·K), and thermal insulation performance is 3-4 times that of traditional rock wool and glass wool; bulk density is only 0.06-0.25g/cm³, greatly reducing the self-weight of thermal insulation structure; after hydrophobic modification, the contact angle is greater than 110°, water absorption rate is lower than 3%, and it can be used stably for a long time in high-humidity and open-air environments; the inorganic silicon skeleton makes it reach Class A non-combustible standard, and the temperature resistance range covers -200℃ to 650℃, suitable for multiple scenarios such as ultra-low temperature cold chain, high-temperature industrial pipelines, and extreme aerospace working conditions.
Current process upgrades focus on precise structural control and green low-carbon. The sphericity and uniformity of particles are improved by optimizing granulation process, enhancing fluidity and filling rate; recycled ethanol and fluorine-free hydrophobic modifiers are adopted to reduce VOC emissions and production costs; meanwhile, pore size distribution is regulated to improve the compressive strength of particles, solving the shortcomings of fragile traditional particles and high pulverization rate, promoting aerogel particles from high-end special materials to a new industrial stage of generalization, high performance and low cost.