Excellent electromagnetic wave absorption properties of SiCN ceramic aerogels via a controlled hydrosilylation reaction

Abstract Polymer‐derived ceramic materials exhibit adjustable composition, microstructure, and dielectric properties and are widely used as high temperature microwave absorption materials in the aerospace field. In this study, polymer‐derived SiCN ceramic aerogels with excellent electromagnetic wave absorption (EMA) properties were successfully fabricated through a combination of the sol‐gel, freeze‐ drying, and polymer precursor conversion methods. The hydrosilylation reaction between the Si‐H bond in polysilazane (a polymer ceramic precursor) and the C = C bond in divinylbenzene (a cross‐linking agent) occurs to form a wet gel. The effects of the molar ratios of the two bonds (C = C/Si‐H) on the microstructure and EMA properties of the SiCN ceramic aerogels were systematically studied. At a C = C/Si–H molar ratio of 1.25:1, the minimum reflection loss of the SiCN ceramic aerogels is −37.57 dB at 10.88 GHz. Moreover, the corresponding effective absorption bandwidth covers almost the entire X‐band, showing excellent EMA properties.