关键词: 生物质衍生法, 碳基复合材料, 磁性, 吸波性能

Abstract:

In response to the national carbon neutrality and carbon emission peak target and in order to solve the potential preparation problem of magnetic carbon composite, it proposed a new biomass-derived strategy for the preparation of carbon-based microwave absorption composites. The iron/mushroom precursor was obtained by absorbing iron ions, where mushrooms acted as the raw material and iron salt severed as metal source. The Fe/Fe₄N/C composites were acquired by controlled high-temperature pyrolysis, and the phase structure, morphology, thermal stability, magnetic stability, physiochemical properties and microwave absorption performance of composites were analyzed and discussed. It was proved that the increased pyrolysis temperature would improve the crystallinity of magnetic nanoparticles, and that the increases in Fe₄N content would induce the decrease of coercivity and saturation magnetization simultaneously. The high pyrolysis temperature was conductive to the transformation from amorphous carbon to microcrystalline graphite,inducing the increased degree of graphitization degree of carbon components. The Fe/Fe₄N/C composite pyrolyzed at 700 ℃ was regarded as the best microwave absorber. With a composite thickness being 4 mm, the effective bandwidth of microwave that could be absorbed reached to 6.64 GHz, from 4.00 to 10.64 GHz. The appropriate impedance matching and synergistic enhancement of dielectric loss and magnetic loss were considered to be responsible for the intensified microwave absorption. It is believed that the research provides a reference for the preparation of magnetic carbon microwave absorbers, and promotes the popularization and application of biomass-derived method.

Key words: biomass-derived method, carbon composites, magnetic, microwave absorption performance