Design Of Electromagnetic Characteristics And Design Of Absorbing And Stealthy Properties Of Iron Base Alloys

In the field of microwave absorption,the research on magnetic materials is gradually diversified,among which soft magnetic materials are the most popular research.Among the soft magnetic materials,FeNi alloy has good ferromagnetism and electrical conductivity,as well as good absorption ability of electromagnetic waves,but there are disadvantages such as poor absorption ability at low frequencies and easy to be oxidized,which makes its application in the field of electromagnetic stealth receive limitations.The component,particle shape and size of the absorbing material are very important factors affecting the absorbing performance.Therefore,by selecting different composite materials and different preparation processes,the influence of the synthesis process and material type on the microwave absorption performance can be investigated to obtain absorbing materials that are less susceptible to oxidation and have better stealth performance at low frequencies.In this paper,a spherical FeNi₃ alloy with high saturation magnetization strength was prepared by liquid-phase reduction method using an iron-nickel alloy as the study system.We first investigated the effect of different FeNi₃alloy mixing ratios on the microwave absorption performance by controlling the filling degree of paraffin and FeNi₃alloys.By measuring the electromagnetic parameters of the samples with different FeNi₃fillings and calculating the microwave absorption performance,we learned that the microwave absorption performance of the samples increased with the increase of FeNi₃fillings.When the filling degree of FeNi₃is 70 wt%,it has better impedance matching ability and shows better microwave absorption properties compared with other filling degrees.When the matched thickness of the sample is at2.35 mm,it shows a strong reflection loss capability,with the strongest reflection loss peak close to-40.33 d B,while the band width of microwave absorption can reach 5.5GHz,with a wide effective absorption frequency range covering almost the entire X and Ku bands（8-18 GHz）,and the bandwidth can be controlled by adjusting the matched thickness to control the bandwidth.However,the absorption bandwidth of the prepared FeNi₃alloy and the absorption performance in the low frequency range still need to be improved.Considering the shortcomings of the absorption performance of FeNi₃alloy in the low-frequency range,we use the Stober method to cover the FeNi₃alloy with Si O₂,and the Si O₂-coated FeNi₃@Si O₂complex can effectively improve the absorption in the low-frequency range and improve the dielectric dispersion effect of the complex,so that the complex can achieve the effect of impedance matching This enables the complexes to achieve impedance matching and thus obtain better microwave absorption performance.By changing the amount of tetraethyl orthosilicate added during the reaction process,the thickness of Si O₂coating can be controlled,and the electromagnetic properties of the complexes can be adjusted.When the amount of tetraethyl orthosilicate added in the reaction process reached 1.5 ml,the real and imaginary parts of the complex dielectric constants had stronger dielectric dispersion effects.After the modification of the cladding,the absorption peak intensity of the absorbing material was increased and shifted toward lower frequencies,showing better microwave absorption performance in the frequency band after 4 GHz.Compared with the pure FeNi₃alloy,the low-frequency absorption performance of the clad absorber material is significantly improved compared with that of FeNi₃alloy,but the absorption bandwidth is still not satisfactory.Therefore,in order to solve the shortcomings of FeNi₃alloy absorbers,the performance of FeNi₃alloy absorbers was improved by rGO coating,which can effectively broaden the absorbing bandwidth of FeNi₃alloy absorbers.By changing the amount of rGO added in the reaction process,the coating effect of rGO can be controlled,and then the material can achieve the impedance matching effect in different absorbing frequency bands.When the amount of rGO in the reaction process reached 2 ml and above,the FeNi₃@rGO composites exhibited good microwave absorption in different frequency bands.Also the matching thickness of the absorbing material was reduced.It is good to improve the absorbing bandwidth as well as the absorption performance of the alloy absorbing material.