Multifunctional C/SiO2/SiC-based aerogels and composites for thermal insulators and electromagnetic interference shielding
Abstract A C/SiO 2 /SiC ternary aerogel was prepared from a formaldehyde–catechol/silicon source via the sol−gel method, supercritical drying, and high-temperature carbothermal reduction. The effects of different carbon/silicon molar ratios on the microstructure, chemical composition, and mechanical and shielding properties of the C/SiO 2 /SiC aerogels were investigated. The fabricated aerogels exhibited low density of 0.118–0.271 g/cm 3 , low thermal conductivity of 0.044 to 0.089 W/(m∙K) and a high specific surface area of 774 m 2 /g. The aerogel exhibited electromagnetic interference shielding effectiveness (SE) properties; the maximum SE value was 24 dB over 12.4–18.0 GHz with an absorption-dominant shielding characteristic. To improve the mechanical properties of the ternary aerogel, novel SiC w -C/SiO 2 /SiC aerogel composites were prepared by adding different contents of SiC whiskers into precursor solutions. The mechanism affecting thermal and mechanical properties of aerogel composites was investigated. This composite having high strength and low thermal conductivity had potential applications in space shuttles and reusable carrier thermal protection materials. The fabricated C/SiO 2 /SiC ternary aerogels exhibited low density of 0.118–0.271 g/cm 3 and low thermal conductivity of 0.044−0.089 W/(m∙K). The aerogel exhibited electromagnetic interference shielding effectiveness (SE) properties; the maximum SE value was 24 dB over 12.4–18.0 GHz with an absorption-dominant shielding characteristic.
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