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.

Enhanced mechanical and wave‐absorption properties of SiC–Si3N4–FeSi porous ceramics by introducing Al

“…This indicates that the input impedance of porous ceramic surface is consistent with the material characteristics impedance, and the RL curve reaches a minimum value under this condition. Figure 7B shows the comparison of the absorption performance of SiC–Si 3 N 4 –FeAl 0.25 Si 0.75 porous ceramics (S3) produced in this work with other similar materials 12,13,21,38–47 . Figure 7C further compares the RL value per unit thickness ($${\mathrm{RL}}_{{\mathrm{min}}}/d$$).…”

“…Figure 7B shows the comparison of the absorption performance of SiC-Si 3 N 4 -FeAl 0.25 Si 0.75 porous ceramics (S3) produced in this work with other similar materials. 12,13,21,[38][39][40][41][42][43][44][45][46][47] Figure 7C further compares the RL value per unit thickness (RL min ∕𝑑). SiC-Si 3 N 4 -FeAl 0.25 Si 0.75 porous ceramics can achieve stronger electromagnetic wave-absorption performance at lower thicknesses compared to materials reported in comparative literature, showing the potential for application as high-performance absorbing materials.…”

Simultaneous microwave absorption and thermal insulation properties of porous rigid mullite by loading SiCN aerogel

“…Hence, the obtained SiCN ceramics possess excellent EMW absorption performance. We synthesized light SiCN ceramic aerogels (SiCN a ) in our previous study [20], and specimen SCA-1.25 reached the minimum re ection loss (RL min ) of − 37.57 dB @ 10.88 GHz. By incorporating SiCN a into PRM, the fabrication of multifunctional integration composites with excellent thermal insulation and EMW absorption performance will become achievable.…”