Polymer-derived Cf/C/SiC ceramic aerogel composites with superior microwave absorption properties

Lightweight yet strongly attenuating microwave absorbers remain in urgent demand. In this article, polymer-derived C f /C/SiC ceramic aerogel composites (CACs) with hierarchical porous structure have been prepared via a sol-gel route followed by freeze-drying. The C f /C/SiC CACs were composed of polyacrylonitrile fibers/hydroxyethyl cellulose (PAN/HEC) derived carbon framework and polycarbosilane derived SiC aerogel. The incorporation of PAN/HEC was used to tailor the conductivity and impedance matching characteristics of CACs, and the permittivity of C f /C/SiC CACs could be adjusted by changing the quantity of PAN fibers introduced or by altering the pyrolysis temperature. After pyrolysis at 900 °C, a ceramic yield of ∼38 % was obtained, together with a BET surface area of 95.63 m 2 /g. Moreover, the C f /C/SiC exhibited an outstanding reflection loss ( RL min ) of −75.19 dB at 12.82 GHz ( d  = 2.52 mm), whereas its effective absorption bandwidth (EAB) was further broadened to 5.9 GHz at 2.24 mm. The superior microwave absorption (MA) performance of C f /C/SiC CACs stems from: (i) hierarchical porous structure that multiply internal reflections, (ii) PAN/HEC-derived carbon framework that optimize the impedance matching, and (iii) synergistic effect of conductivity loss and interfacial polarization loss. The optimal preparation temperature is 700 °C, lower than that of comparable ceramic-based absorbers. Therefore, this research provides a low-cost and convenient method to fabricate MA materials with lightweight and high-performance.