Graphene/carbonyl iron powder composite microspheres enhance electromagnetic absorption of 3D printing composites

The RGO-CIP composite microspheres were prepared by solvent evaporation method using ethyl cellulose as the backbone and epoxy resin as the adhesive. The composite microspheres effectively combined graphene (RGO) with carbonyl iron powder (CIP) to achieve the synergy of multiple loss mechanisms and obtain good electromagnetic absorption capability. 3D printed wire was prepared by using RGO-CIP composite microspheres and polylactic acid (PLA), and coaxial rings were printed by fused deposition molding (FDM) to test electromagnetic properties. In this study, many heterogeneous interfaces triggering polarization loss are formed on the surface and inside of the composite microspheres. These heterogeneous interfaces produce abundant folds and pores, which enhance the multiple reflections and scattering of microwaves. The added RGO and CIP forms a conductive network, forming a conductance loss. When the RGO content is 5.1 wt%, RGO-CIP/PLA −4 composite exhibits excellent microwave absorption performance. At the material thickness of 2.2 mm, the maximum reflection loss is −50.1 dB and the absorption bandwidth is 6.0 GHz. At the material thickness of 2.2 mm, the effective absorption bandwidth is 6.24 GHz and the maximum reflection loss is −29.08 dB. The RGO-CIP composite microspheres improve the microwave absorption performance of 3D printed composites and provide an effective way to prepare structural wave absorbing plates and devices by 3D printing technology.