Structural Design And Microwave Absorption Properties Of CoNi/RGO Composites

The ever-expanding reach of electromagnetic information technology has resulted in electromagnetic wave radiation permeating the environment,potentially causing interference between components,resulting in electromagnetic information leakage and other issues.Microwave absorption materials（MAM）are widely used in military or civilian applications by converting electromagnetic energy into heat or other forms of energy dissipation.In recent years,various types of wave-absorbing materials have been discovered,however,each of them has certain application limitations,therefore,the advantages of complementary,optimal composite become the future research trend of new wave-absorbing materials.Cobalt-nickel（CoNi）alloys have received a lot of attention because of their high permeability,high saturation magnetization strength,low cost,and flexible structure,etc.However,the disadvantages of single-component CoNi alloys,such as high density,easy oxidation,and single loss mechanism,make it hard to address the issues of large attenuation coefficient and impedance matching simultaneously,thus restricting their further progress.To counter this,two strategies are typically employed:material compounding and structural design.In order to overcome this shortcoming,two strategies are usually used:material compounding and structural design.In order to overcome the above problems,the following strategies are proposed in this paper.On the one hand,the CoNi alloy is compounded with dielectric type material to make it have both magnetic and dielectric losses,and on the other hand,the impedance matching and attenuation characteristics of the material are improved by constructing a new structure,and the loss mechanism and wave absorption characteristics of the CoNi-based composite are studied.Division of the research contents and results is mainly into the following points.（1）CoNi alloys were prepared by the solvothermal method,and chain CoNi alloys and granular CoNi alloys were obtained at different reaction times by adjusting two factors:（a）magnetic field induction;and（b）reaction time,respectively.Microscopy and SEM images confirm the growth of CoNi alloys and the formation of chains under magnetic field induction,XRD characterization reveals the material phase composition,VSM measurements explain the magnetic properties of CoNi alloys,and finally,by measuring the electromagnetic parameters of the samples,it is calculated that:the CoNi-C-9 sample has better wave absorption properties with RL_min=-42.113 d B（16.5 GHz）and EAB=3.5 GHz（13-16.5 GHz）,and its superior performance may originate from more conductive losses,abundant interfacial polarization,eddy current effects,exchange resonance,multiple reflections and scattering.（2）The RGO aerogel was prepared by ethylenediamine reduction method,and the CoNi/RGO aerogel structure was obtained by adjusting the mass ratio of CoNi-C-9 to GO.microscopic porous structure of the aerogel was observed by SEM image,XRD characterization explained the full reduction of GO to RGO,Raman spectral analysis and macroscopic observation proved that the CoNi content had no The BET specific surface area analysis obtained the porosity in the RGO aerogel with different contents of CoNi.Finally,by measuring the electromagnetic parameters of the samples,it was calculated that the CoNi/RGO aerogel has potential wave absorption properties due to its unique porous structure and the synergistic effect between different components.（3）Using CoNi-C-9 absorbers to prepare CoNi-PVDF film as the sandwich layer and RGO-paraffin aerogel as the outer layer,the RGO/CNP/RGO sandwich structure was formed by hot pressing method to study the influence of the number of layers on the performance.In addition,a new strategy was applied to evaluate the effective absorption properties of the absorbers in a comprehensive manner:ΔS is defined as the integrated area for RL≤-10 d B,R_E is defined as the electromagnetic absorption efficiency,and a larger R_E indicates a higher comprehensive evaluation of the material.The higher R_Eindicates a higher overall evaluation of the material,whereΔS=122.53 d B·GHz and R_E=40.84 d B·GHz/mm for the 3+2 type sandwich structure.