Structural-Functional-Integrated Ultra-Wideband Microwave-Absorbing Composites Based on In Situ-Grown Graphene Meta-nanointerface

Ultra-wideband microwave absorbing (MA) materials covering the low-frequency range (2–6 GHz) are highly desirable in civil and military fields. These materials can be fabricated based on the design of electromagnetic meta-structure. Herein, a structural-functional-integrated ultra-wideband SiO₂ fiber reinforced cyanate ester (CE) MA composite based on an in situ-grown graphene meta-nanointerface layer (GrMI) (SiO_2f/GrMI/CE) is reported. The relationship between the periodic structure of the graphene nano-interface layer and the MA performance is discussed through experiments and simulations. The results show that SiO_2f/GrMI/CE with a thickness of 8.78 mm exhibits an effective absorption bandwidth of 15.46 GHz (2.54–18 GHz). Remarkably, the reflection loss remains basically unchanged upon increasing the incident angle from 5° to 50°. Additionally, GrMI is an effective load-bearing constituent, which increases the interfacial shear stress between SiO_2f and the CE by ≈210% and contributes to achieving composites with an ultra-high flexural strength (552.7 MPa). The excellent structural-functional-integrated performances ensure that the SiO_2f/GrMI/CE composites are suitable for use as the skin materials of microwave stealth aircraft and other civil facilities. The work provides a novel pathway for the design of thinner, wider, lighter, and stronger MA components.