Controllable synthesis of porous carbon@Fe20Ni80 composites with improved microwave absorption performance

The two-component composites with porous carbon and magnetic metals exhibit a promising application prospect in microwave absorption due to their superior impedance matching and excellent loss ability. Herein, a novel process combined sol-gel and in-situ pyrolysis methods was proposed to prepare a series of porous carbon@Fe20Ni80 composites. The structure and composition of composites were controlled by adjusting pyrolysis temperature and doping amount of Fe20Ni80 for achieving an improvement on microwave absorption performance. Under the optimal Fe20Ni80 doping amount of 2 mmol, the composite pyrolyzed at 800 degrees C shows the highest performance. With 15 wt% filler loading, the composite achieves the minimum reflection loss value (RLmin) of-39.5 dB at 6.7 GHz with a thickness of 3 mm. Moreover, under the optimal matching thickness of 2.2 mm, the maximum effective absorption bandwidth (EABmax) reaches 5.4 GHz (8.0-13.4 GHz), covering the whole X-band. The porous structure is maintained at appropriate pyrolysis temperature, which optimizes the impedance matching of materials. The porous carbon matrix with partial graphitization exhibits the dielectric loss ability to electromagnetic waves. In addition, the introduction of Fe20Ni80 endows the composite with magnetic loss ability. This study develops an avenue for the preparation of two-component composites with porous carbon and magnetic metals and has potential application in microwave absorption.