Preparation and properties of CF-Fe₃O₄-BN composite electromagnetic wave-absorbing materials

A three-layered electromagnetic (EM) wave-absorbing material was prepared by depositing a Fe₃O₄ and boron nitride (BN) coating onto the surface of a carbon fiber (CF) by in situ hybridization. The structure, chemical composition, morphology, high-temperature resistance, EM characteristics and EM wave absorption of the composite materials were analyzed. The composite materials contained CFs, and Fe₃O₄ was distributed along the axial direction of the fiber, whereas BN was found in the outermost coating layer. The proposed preparation method improved the oxidation resistance and EM wave absorption of CF. When the solubility of the metal salt was 20 g/100 ml, the decomposition temperature of the prepared CF/Fe₃O₄(3)/BN increased by more than 200 °C compared with that of CF/Fe₃O₄(3). The EM wave loss of less than -5 dB ranged within 8.8-18 GHz, and the effective EM wave-absorbing bandwidth (R < -10 dB) was 4.2 GHz (11.2-15.4 GHz). The prepared CF-based composite material had a lightweight structure, wide absorption band, and strong oxidation resistance. All these findings can serve as a reference for the study of other EM wave-absorbing materials.