Study On Preparation And Properties Of Graphene Sandwich Honeycomb-Like Absorber By FDM

The problem of electromagnetic pollution is becoming more and more serious,and it is urgent to develop absorbing materials with thin thickness,light weight,wide frequency band and strong absorption.From the perspective of material properties,carbon materials(graphite,graphene,etc.)have attracted extensive attention for their excellent characteristics such as low density,high conductivity and corrosion resistance.In particular,graphene’s unique pore wall and two-dimensional structure of single atom make it have large specific surface area,good mechanical properties and good conductivity.And it is expected to be used as a light and efficient absorber in the field of electromagnetic wave absorption.From the structural design,the honeycomb structure has strong bearing capacity.Its special hole units can provide complex propagation paths for electromagnetic wave transmission and reflection,consume a lot of electromagnetic wave energy,save materials and reduce weight.In this paper,based on the development of polylactic acid(PLA)/thermoplastic polyurethane(TPU)based multi-element 3D printing composite wire,the corresponding composite sample and graphene sandwich honeycomb structure absorber were prepared by fused deposition modeling(FDM)technology,which provided a new method for the design and manufacturing of high-performance absorbing material structures.The main research is as follows:By testing and comparing the micro-morphology,phase structure,graphitization degree,electromagnetic parameters,tensile strength and elongation at break of five PLA/TPU composites,including micropowder graphite(MPG),spherical graphite(SG),graphene(GR),graphene nanoplatelets(GNPs)and copper-coated graphite(CCG),the reflectivity,attenuation constant and impedance matching were calculated,and the absorption of different carbon composites was emphatically studied.It is found that MPG and SG have good dispersion effect;GNPs impedance matching is good;GR and CCG have strong dielectric loss ability.Adding SG or Fe-Ni alloy(Fe Ni50)into GR,the properties of SG/GR/PLA/TPU and GR/Fe Ni50/PLA/TPU composites with different content ratios were mainly studied.It is found that when the content of GR is high,polarization and multiple scattering are promoted,and the composite material has excellent absorbing performance.When SG content is high,it promotes particle dispersion and the mechanical properties of composites are excellent.With the addition of magnetic medium Fe Ni50,natural resonance,exchange resonance,eddy current effect and other magnetic losses are introduced,and the absorbing effect is greatly improved.Combining impedance gradient design with electromagnetic simulation(CST)optimization,the best graphene sandwich honeycomb absorber is obtained,and the maximum reflection loss is-51.19 d B at a thickness of only 6 mm.The simulation results verified by FDM absorber test show that the effective absorption bandwidth(R_L<-10 d B)reaches 8.88GHz(3.99～6.59 GHz,9.57～15.85 GHz),which preliminarily realizes the synergistic effect of material structure,and provides a useful reference for the wide-band absorber with strong absorption,high strength and high toughness.