Natural magnetite/coke composite: A novel promising microwave absorption material

Fe3O4 and carbon materials are the two most common materials in research on microwave-absorbing materials. However, in previous studies, the material sources of Fe3O4 and carbon materials mostly came from the addition of chemical reagents, which meant that expensive raw materials and complex preparation processes restrict the large-scale production and application of microwave-absorbing materials from the raw material level. The preparation of highly efficient electromagnetic wave-absorbing materials from natural mineral resources may be the key way to solve this problem. In this work, pure magnetite minerals and original coking coal were used as the sources of Fe3O4 and carbon materials in the composite material. Through the combination of mixed ball milling and high-temperature roasting, the two natural mineral materials were successfully combined to prepare a magnetite/coke composite material with a porous network structure (Ma/Coke). After carbonization, a continuous network was formed to effectively coat or load magnetic magnetite particles, which formed the electromagnetic cooperative loss mechanism. By optimizing the material ratio, the microstructure of the composite was effectively regulated, and the impedance matching of the material was improved, showing excellent electromagnetic wave-absorbing performance. Ma/Coke-0.5 had a minimum reflection loss (RLmin) of − 57.86 dB and an effective absorption bandwidth of up to 5.47 GHz. This work provides a low-cost, high-efficiency, environment-protecting, and large-scale preparation method for electromagnetic wave-absorbing materials based on natural minerals and provides a new feasible suggestion for the functional application of natural mineral materials.