Fe2O3/SiO2 composite aerogels powders for high-temperature thermal insulation based on EDTA chelated aqueous precursor

Abstract SiO₂ aerogel is a typical thermal insulation material suitable for varied high temperature industrial applications. However, its radiative transparency seriously hampers its application scenario. Herein, we integrated infrared (IR) opacified Fe₂O₃ nanoparticles into silica aerogel system and developed a Fe₂O₃/SiO₂ composite aerogel (FSA) by using industrial water glass and ambient pressure drying process. Especially, we chelated Fe³⁺ with disodium ethylenediaminetetraacetic (EDTA-2Na) to avoid the loss of Fe³⁺ in the gelling, solvent-exchanging and hydrophobic modification processes. FSA powders with 3-11% concentration exhibit an amorphous structure, high porosity with small nanopores (11-12 nm). The EDS analysis confirms the presence of Fe in the aerogel framework. The high-temperature thermal insulation properties of the FSA powders were enhanced compared with the pure SiO₂ aerogel powders, yielding a cold surface temperature of 456 ℃ after heating at 600 ℃ for 30 min, 26 ℃ lower than pure SiO₂ aerogel. The EDTA-2Na chelating agent improves the dispersion of Fe³⁺ and further reduces the temperature by 6 ℃, demonstrating its positive effect on the insulation performance.