The development of electromagnetic wave absorbers, which have widespread application prospects, requires new lightweight, multifunctional materials that can be used in harsh environments. Herein, ultralight SiC/Si₃N₄ aerogels are prepared by freeze-drying and carbothermal reduction reaction, and their microstructures were investigated by transmission electron microscopy, Raman spectroscopy, and X-ray absorption near-edge structure at the N K-edge. The result of morphology analysis indicates that the porous structure of SiC/Si₃N₄ aerogels are composed of SiC and Si₃N₄ nanowires. The optimal prepared SiC/Si₃N₄ aerogel possesses high absorption performance with a minimum reflection loss of −25 dB and a wide effective absorbing bandwidth of 4.3 GHz (6.1–10.4 GHz) at a thickness of 3.97 mm. Such superior absorption performance is due to excellent impedance matching and enhanced polarization loss. Moreover, the SiC/Si₃N₄ aerogel is thermostable under air atmosphere below 1100°C, which can be attributed to the presence of Si₃N₄. These achievements suggest that SiC/Si₃N₄ aerogel is promising candidate for electromagnetic wave absorption in harsh environment.

开发具有广泛应用前景的电磁波吸收器需要可用于恶劣环境的新型轻量化、多功能材料。在此，通过冷冻干燥和碳热还原反应制备了超轻SiC/Si ₃ N ₄气凝胶，并通过透射电子显微镜、拉曼光谱和N K 边缘的X 射线吸收近边结构对其微观结构进行了研究。形貌分析结果表明，SiC/Si ₃ N ₄气凝胶的多孔结构由SiC和Si ₃ N ₄纳米线组成。最佳制备的SiC/Si ₃ N ₄气凝胶具有高吸收性能，最小反射损耗为-25  dB，有效吸收带宽为4.3  GHz（6.1-10.4  GHz），厚度为3.97  mm。这种优异的吸收性能是由于出色的阻抗匹配和增强的极化损耗。此外，SiC/Si ₃ N ₄气凝胶在低于1100℃的空气气氛下具有热稳定性，这可归因于Si ₃ N ₄的存在。这些成果表明，SiC/Si ₃ N ₄气凝胶有望成为恶劣环境下电磁波吸收的候选材料。