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

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.