Abstract: SiO₂ aerogel flexible composites have become a research hotspot in the aerogel industry due to their good flexible, processability, thermal insulation and other properties. However, SiO₂ aerogel flexible composites generally face a series of problems, such as high cost, high thermal conductivity, difficult uniform dispersion, poor stability and low solid content. In this study, SiO₂ aerogel was prepared by sol-gel method combined with atmospheric pressure drying process. SiO₂ aerogel was used as the core raw material, and SiO₂ aerogel coating was prepared by adjusting the solid content of SiO₂ aerogel powder and stirring dispersion process. Subsequently, SiO₂ aerogel coatings were compounded with spandex substrates by coating technology to prepare SiO₂ aerogel flexible composites. The effect of SiO₂ aerogel solid content on the structure and properties of the SiO₂ aerogel flexible composites was systematically investigated by microstructure characterization and performance testing. The results show that the apparent density of the self-made SiO₂ aerogel is 0.07 g/cm³, and the specific surface area is as high as 872 m²/g. When the SiO₂ aerogel solid content is 8% (mass fraction), the thermal conductivity of the SiO₂ aerogel flexible composite with the thickness of 1 mm is as low as 0.023 W/(m·K), and it can be insulated above 30 ℃ at 150 ℃. In addition, the minimum temperature difference between the material surface and the environment is only 1.1 ℃ after the copper foil is compounded with the SiO₂ aerogel flexible composite material with a SiO₂ aerogel solid content of 4% (mass fraction). This study provides an important reference for the application of high solid content SiO₂ aerogel flexible composites in the fields of thermal insulation, infrared stealth and so on.

Key words: SiO₂ aerogel, aerogel coating, composite, ambient pressure drying, thermal insulation performance, flexible, infrared stealthy