Gradient Structure Design And Damping Performance Of Flexible Electromagnetic Protection Absorber

With the rapid development of modern information technology,radio technology has been widely used in military,medical,transportation,civil and other fields.However,while improving people’s daily life,an environment full of artificial electromagnetic radiation is gradually formed.Electromagnetic interference(Electromagnetic Interference,EMI)will cause harm to other electronic products and cause severe pollution to the environment where people live.Therefore,the development of electromagnetic microwave absorption(Electromagnetic Microwave Absorption,EMA)materials with excellent performance has become an urgent need of society.The content studied in this paper is based on CoNi-based heterogeneous electromagnetic composite particles and sea urchin-like self-assembled CNT@CoNi coated with CoNi with different ranges.First,self-assembled sandwich CNT@CoNi covered with varying proportions of CNT and MXene were prepared,respectively.Next,/MXene,use this as a precursor and then compound Ecoflex to design a series of single-layer and multi-layer electromagnetic elastomers.The specific work is as follows:(1)The size distribution of the CNT@CoNi composite particles prepared by the liquid-phase reduction method is 300-500 nm.In the studied frequency range of 2-18 GHz,the dielectric relaxation of the sample is mainly manifested as dipole polarization and interface polarization.In contrast,dipole polarization is caused by electromagnetic particles.The main loss mechanisms of magnetic materials are eddy current loss,natural and exchange resonance,etc.The experimental test analysis found that in the CNT@CoNi elastomer sample of composite CNT,the absorbing effect is better when the CNT content is 200 mg.The bandwidth greater than-10 dB is 4.3 GHz,and the corresponding absorbing thickness is 4 mm.Through the mechanical property test,the Bouc-Wen model was used for modelling,the variation law of each parameter under different applied currents was analyzed,and a generalizedBouc-Wen model suitable for this sample was concluded.The relative error between the model’s predicted value and the experimental weight is concentrated at about 15%.Through tensile experiments,the more the amount of CNTs doped in the substrate,the smaller the elongation at the break of the elastomer,and if the doping is more significant than 250 mg,the breaking strength curve of the material will drop significantly.(2)The particle size of the CNT@CoNi/MXene composites prepared by the liquid-phase reduction method is about 3-5 μm.In the studied frequency range of 2-18 GHz,the researchers found through experimental test analysis that in the CNT@CoNi/MXene elastomer samples composited with different ratios of CNT and MXene,when the ratio of CNT and MXene was 5:5,the wave absorption effect The best is achieved,the bandwidth greater than-10 dB is 7 GHz,the corresponding reflectivity and material thickness are-65 dB and 2 mm,respectively,and the absorption intensity is enhanced by about 18% compared with the pure composite CNT.Furthermore,in the electrical conductivity test,compared with the samples of pristine composite CNT,the introduction of MXene did not reduce the conductivity of the material,indicating that after the surface of MXene was successfully composited with CNT@CoNi,a complete conductive network could still be formed,so that the wave absorbing properties of the samples were improved.Improve.(3)The multi-layer material structure prepared by physical casting can improve the waveabsorbing performance of the composite elastomer.For example,the wave-absorbing strength of the double-layer material is about 9% higher than that of the CNT@CoNi elastomer in Chapter III.Compared with the CNT@CoNi/MXene elastomer in Chapter 4,the absorbing strength is about 25% higher,and the corresponding material thickness is correspondingly reduced,mainly due to the improvement of impedance matching and multiple reflections.Furthermore,since the multi-layer materials are combined by physical pouring,a bonding surface is subject to the resistance between different bonding surface layers during tensile fracture.Therefore,the mechanical tensile fracture performance of the multi-layer material is compared with that of the single layer and significantly enhanced.