Fabrication And Electromagnetic Protection Properties Of Novel Composite Materials Filled With Metallized Graphite

With the rapid development of electronics industry,Electromagnetic waves have been widely used in various fields,such as scientific research,industrial production,as well as daily life.However,the accompanying electromagnetic radiation has caused increasing environmental and health problems.To address these problems,electromagnetic protection material has gradually come into field vision of people.Preparing material by compositing carbon-based material with magnetic material has already became the research hotspot of international and domestic academics,which can meet the requirements of "thin,light,wide and strong" for absorbing material.The core-shell structure FeNi alloy-coated flake graphite(FeNi-G)was prepared by electroless plating,and the electroless process,microstructures,compositions and magnetic properties were studied in this paper.The prepared FeNi-G as filler exhibit excellent absorbing properties and electromagnetic shielding properties.It is expected to be played an important role in the field of electromagnetic protection.We successfully fabricated FeNi-P alloy-coated flake graphite with uniform low phosphorus FeNi alloy coating using sodium hypophosphite as reducing agent,and explored the influence of different parameters on electroless process in this paper.The content of phosphorus was 4.85 wt% and the ratio of iron to nickel was 0.20 in the coating.The XRD patterns showed that the coating was amorphous phase.The VSM analysis revealed that the saturation magnetization increased in different extent with the increase of Fe content in the coating.In order to obtain pure FeNi alloy coating on graphite surface and get high iron content,we successfully fabricated FeNi alloy-coated flake graphite using hydrazine as reducing agent,and explored the influence of different parameters on electroless process.In the coating,the ratio of iron to nickel was increased to 0.98,and the FeNi alloy coating was typical FeNi3 phase.The VSM analysis revealed that the saturation magnetization was 37.5emu/g,which showed excellent magnetic properties.The absorption performance and shielding effectiveness of FeNi alloy-coated flake graphite were tested.By calculating the reflection loss of different absorber thicknesses,The FeNi-FG/paraffin composite possessed good absorption properties with a minimum RL of-43.7 dB at 12.5 GHz,and an absorption band with RL under-10 dB from 11.2 to 14.1 GHz,which corresponds to the matching thickness of 1.2 mm.By testing the shielding effectiveness of ABS based composites,the ABS composites containing FeNi-G fillers showed excellent shielding effectiveness in the frequency range of 30~1200MHz when the loading level of FeNi-G was 15 wt%.In addition,the surface morphology and magnetic properties of the prepared sample were analyzed after expanding production.