Microwave absorption and flexural properties of Fe nanoparticle/carbon fiber/epoxy resin composite plates

Abstract

A flat nanocomposite plate was fabricated by using the surface-modified Fe nanoparticles (NPs) as the microwave absorbent, carbon fibers (CFs) as the reinforced phase and epoxy resin (ER) as the matrix. Fe NPs were synthesised by an arc discharge plasma method and subsequently modified by silane coupling agent (KH-550) to improve its dispersion in the organic matrix of ER. To measure the realistic microwave absorption properties of such a flat nanocomposite plate, a series of square plates (20×20cm2) was made from recombining the modified Fe NPs (20wt.%, 30wt.% and 40wt.%) into the ER matrix with/without orientated CFs inside. It was observed that the orientation of CFs plays an important role in the microwave absorption, in particular through a strong reflection of microwave inwardly as the CFs’ array is vertical to the direction of incident microwave. The inner strong reflection of microwave by CFs can bring great probabilities to further consume it by Fe NPs absorbent and result in improved microwave absorption performance of the nanocomposite plate. It is indicated that the plate containing 30wt.% of Fe NPs with a perpendicular manner between the directions of CFs array and incident microwave exhibits higher reflection loss (RL) of −16.2dB at 6.1GHz frequency, and this plate has 77.78MPa flexural strength at 3.74% deformation. Excellent RL property is ascribed to an optimum structure of nanocomposite plate with favorable multi-reflection of microwave inside, structural resonance, appropriate conductivity, impedance match, interface polarization.