Fe nanoparticles decorated in residual carbon from coal gasification fine slag as an ultra-thin wideband microwave absorber

Microwave absorbing materials are widely used in the defense and telecommunications industries, as means for enhancing battlefield penetration rate and improving the protection of precision instruments. The magnetic dielectric Fe@ residual carbon from coal gasification fine slag (Fe@RC) nanocomposites were fabricated via a chemical coprecipitation and thermal annealing method, in which involve a reduction process from the Fe3O4 to Fe metal. The structure, morphology, compositions and electromagnetic parameters of the as-prepared Fe@RC materials were characterized. The obtained nano-micro scale Fe@RC shown adjusting electromagnetic parameters and outstanding microwave absorbability. The optimized reflection loss value of-47.1 dB was attained at 5.5 GHz for Fe@RC, and the effective bandwidth is 5.3 GHz (12.4-17.7 GHz) at a matching thickness of 1.5 mm. Benefit from good impedance match, special space architecture and synergistic effect between the dielectric loss from RC component and magnetic loss from Fe component, this Fe@RC materials are expected to be a potential microwave absorber. The simulated radar cross section (RCS) results prove that the Fe@RC can efficaciously reduce the microwave scatterings of the perfect electric conductor substrate at different degrees in C-, X-, and Ku bands via adjusting the Fe@RC coating thickness. The low-cost carbon-based magnetic nanocomposites display an ultra-thin wideband microwave absorption ability and high RCS reduction performance, promoting resource utilization of the RC from coal gasification fine slag.