Honeycomb structure SiC_f/Si₃N₄ composite with broadband electromagnetic absorption performance under a wide temperature range

SiC_f/Si₃N₄ composites have the potential to be high-temperature absorbing materials, but the impedance mismatch caused by the high dielectric properties leads to narrow absorption bandwidth. Herein, the strategy of combing the high dielectric properties of SiC_f/Si₃N₄ with a periodic structure design was proposed to broaden the absorption bandwidth. The honeycomb structure of the fiber preform was firstly prepared by integrated molding, and the BN interphase and Si₃N₄ matrix were prepared by chemical vapor infiltration to obtain honeycomb structure SiC_f/Si₃N₄. Through structural parameter design, the effective absorption bandwidth (reflection loss ≤ −10 dB) can achieve 13.1 GHz (4.9–18 GHz) at 25 °C, and it remained 10.5 GHz (7.1–17.6 GHz) when the temperature increases to 1000 °C. The excellent broadband absorption performance is attributed to the high loss ability of SiC_f/Si₃N₄ and the improved impedance matching provided by the honeycomb structure.