Preparation And Microwave Absorbing Properties Of Graphene-based Magnetic Particle Functional Composites

Graphene,as a new type of two-dimensional carbon material,is often obtained by chemical reduction of graphite oxide.During the reduction process,there are many defects and residual functional groups,which are beneficial to electromagnetic wave attenuation.Generally speaking,the absorption characteristics of materials depend mainly on two parts,impedance matching and attenuation characteristics.Graphene has a high dielectric constant,but the lack of permeability makes it difficult for pure graphene materials to meet the requirements of high absorbing properties.Therefore,in order to obtain magnetic permeability,graphene is often used in conjunction with magnetic particles.Because of its strong saturation magnetization and permeability,CIP is often used as a magnetic strengthening material in conjunction with RGO.However,for the characteristics of high conductivity and low impedance with CIP,the main way to reduce the conductivity is to coat the CIP surface with insulating layer.Core-shell structure can improve the surface properties of materials and adjust the flow channel of information.In this paper,CIP@Fe₃O₄ was prepared by wet chemical in situ oxidation on CIP surface.RGO-CIP@Fe₃O₄ and r-GCF?GO-CIP@Fe₃O₄ with different reduction degree?were successfully prepared by wet chemical oxidation and bridging process.Firstly,we studied the reaction time of CIP in oxidant solution,the preparation and properties of CIP@Fe₃O₄particles.Secondly,the microwave absorbing properties of RGO-CIP@Fe₃O₄ composites were studied.Finally,the relationship between the reduction degree of graphene oxide and the properties of r-GCF composites was discussed.In addition,the effect of the amount of the optimum absorbent obtained from r-GCF composites added to the organic silica gel on the overall absorbing properties of the material was discussed.?1?The effect of reaction time on the composition of CIP@Fe₃O₄ was studied.It was proved that there were new substances in the system through the change of sample color and the change of material morphology in SEM.The results of XRD and XPS supported each other and proved that ferric oxide was successfully synthesized in situ on CIP surface in this experiment.And through the software of particle size measurement on SEM,it can be seen that the particle size distribution is in the range of 20-40 nanometers.The magnetic properties of the products obtained at different reaction time were studied.It was found that CIP@Fe₃O₄had good magnetic properties.?2?The effects of different mass combinations of GO and CIP@Fe₃O₄ on the absorbing properties of RGO-CIP@Fe₃O₄ materials were studied.Through the mutual support of SEM,XRD and XPS test results,it is proved that RGO-CIP@Fe₃O₄ ternary composites were prepared by bridging process in this experiment,which did not change the surface material of CIP.And through the software of particle size measurement on SEM,we can see that the particle size of Fe₃O₄ has not changed in the process of measurement.By adjusting the mass ratio of GO to CIP@Fe₃O₄,the RGO-CIP@Fe₃O₄?2?composite samples in the product have strong electromagnetic wave absorption performance in paraffin matrix.At this time,the minimum reflection loss is about-53.3 dB,and the maximum effective absorption bandwidth is 6.4 GHz?11.6-18 GHz?.?3?The effect of GO reduction degree on the microwave absorption properties of r-GCF materials was studied.The r-GCF-1 was filled into organic silica gel.By changing the filling ratio of r-GCF-1 in organic silica gel,it was found that when the mass ratio of r-GCF-1 in r-GCF-1/organic silica gel composite was 30%,the electromagnetic absorbing material had better electromagnetic absorption ability.When the thickness of the material was 3.5 mm,the depth of the absorption region was more than 10 dB?RL<-10 dB?in the frequency range of9.5-17 GHz?bandwidth was 7.5 GHz?,the minimum reflection loss of materials near 12.6GHz is-32.1 dB.When the thickness of the material is 4.0 mm,there is a strong microwave absorption peak near 10.3 GHz.The corresponding minimum reflection loss is about-36.7 dB.In the frequency range of 8.1-14.2 GHz?6.1 GHz?,the depth of the absorption zone exceeds10 dB?RL<-10 dB?.In the frequency range of 5.0-18 GHz,the corresponding thickness ranges from 2.5 mm to 5.5 mm,and there are materials with absorption strength of more than 10 dB?RL<-10 dB?.These results show that r-GCF-1/organosilicon gel composite has better microwave absorption performance in low and high frequency bands.