Microwave absorption and infrared stealth performance of reduced graphene oxide-wrapped Al flake

A novel Al@reduced graphene oxide (Al@RGO) composite was designed and synthesized by a one-step hydrothermal method. We investigated the effect of the graphene on the microwave absorbing properties and infrared emissivity of composites. The crystal structure, microscopic morphology, infrared emissivity and electromagnetic parameters of the prepared samples were characterized by XRD, FESEM, TEM, XPS, dual band infrared emissometer and vector network analyzer. TEM and SEM show that the thin Al sheet is uniformly wrapped by RGO with a crumpled surface. Functionalized RGO and surface cation-modified Al sheets are tightly compounded through an electrostatic interaction. The oxygen content and defect from RGO as polarization center endows the material with enhanced molecular polarization and dipole polarization effect. The Al sheet is well coated with RGO, enhancing interface polarization and impedance matching. The minimum reflection loss (RL) of optimized Al@RGO composites is - 46.11 dB at 13.68 GHz under the coating thickness of only 2 mm. The bandwidth below - 10 dB can reach 4.88 GHz (11.52-16.4 GHz). Al sheet is a suitable base material for both microwave absorption and infrared stealth. The Al@RGO composites exhibit excellent infrared stealth ability, and their lowest infrared emissivity is 0.62. Thus, Al@RGO composites show potential application for both electromagnetic wave absorption and infrared stealth.