Hybrid-structured carbon fiber fabric/silk fiber non-woven fabric/carbonyl iron powder/epoxy composites with highly efficient electromagnetic interference shielding and mechanical properties

In this study, carbonyl iron powder (CIP) was loaded onto the surfaces of carbon fiber fabric (CF) and silk nonwoven fabric (SF) through a spraying process and surface micro-dissolve & adhesion (SMDA) process, respectively. Subsequently, CF/SF/CIP reinforced epoxy (CF/SF/CIP/EP) composites with different hybrid structures were fabricated using vacuum-assisted resin transfer molding (VARTM) technique. The effects of these hybrid structures on both the electromagnetic interference (EMI) shielding performance and mechanical properties of the composites were systematically assessed. The results reveal that with an increase in the layer fraction of CF, the mechanical properties of the modified hybrid fibers (HFs) composites demonstrate a positive hybrid effect. Particularly noteworthy is the observation that when the layer ratio of CF to SF is maintained at 1:1, the M-CSCS/ EP composites featuring an interlayer hybrid structure exhibit the highest EMI shielding effectiveness of 34.9 dB within the X-band of 8.2-12.4 GHz. This enhancement is attributed to the improved interfacial polarization loss capability of incident electromagnetic waves, facilitated by the increased two-phase interface formed between CF and SF. Moreover, the composite exhibits excellent mechanical properties, including a tensile strength of 339.9 MPa, interlaminar shear strength of 32.1 MPa, and impact strength of 98.2 kJ/m(2). Consequently, the HFs composites developed in this study offer a commendable balance between EMI shielding performance and mechanical properties, rendering them highly suitable for a wide array of applications in aerospace, rail transportation, and communication equipment.