Investigation of the microwave absorbing properties of carbon aerogels

Carbon aerogel is a new kind of functional material. In this paper, carbon aerogel is prepared by solvent exchange instead of supercritical-drying. The catalyst concentration influences the microstructure of carbon aerogel greatly. By changing the resorcinol per catalyst (R/C) molar ratio, polymeric and colloidal carbon aerogel are formed. The absorbing properties of carbon aerogel are influenced by its microstructure and density. The maximum reflection coefficient is about −22 and −32 dB for the polymeric and colloidal carbon aerogels, respectively. The bandwidth corresponding to the reflection coefficient below −10 dB is more than 5 GHz for both structures. With increasing thickness, the peak value of the reflection coefficient moves to lower frequency.