Graphene nanosheet- and flake carbonyl iron particle-filled epoxy–silicone composites as thin–thickness and wide-bandwidth microwave absorber

An epoxy–silicone matrix filled with both graphene nanosheets (GNs) and flake carbonyl iron (FCI) particles was prepared, and the influence of GNs and/or FCI particle content on the electromagnetic and microwave-absorbing properties was investigated in the frequency range of 2–18 GHz. Thin–thickness, broadband absorption microwave absorbers with homogeneously dispersed GNs and FCI particles were obtained. The values and frequency dependencies of the electromagnetic properties of such absorbers can be adjusted by simply changing the content of GNs and/or FCI particles. These changes led to an apparent improvement of impedance matching and then significantly improved the microwave absorptions. Reflection loss values exceeding −6 dB (>74.9% absorption) can be obtained in the frequency range of 5.4–18 GHz with a thickness of 0.9 mm.