Preparation And Electromagnetic Wave Absorption Performance Of Flaky FeSiAl Composites

With the rapid development of modern electromagnetic wave application technology,it not only provides convenience,but also brings hidden dangers to people,and there are higher and higher requirements for electromagnetic wave absorption materials.In this paper,based on the studies related to flake FeSiAl,the dielectric constant of FeSiAl was reduced by coating oxidex and metallic oxide and MOF materials on the surface of FeSiAl,so as to improve the impedance matching performance of the composites.In addition,the hierarchical structure of the coating material provides abundant interface polarization,which scatters the propagating microwave for many times,resulting in the absorption and dissipation of electromagnetic waves.In this paper,the effects of different semiconductors,coating thickness of materials on the electromagnetic properties of composites were mainly studied as follows:（1）The coating thickness of TiO₂in FeSiAl@TiO₂is changed by changing the addition amount of tetrabutyl titanate.When the concentration of tetrabutyl titanate is0.22 mol/L,the maximum bandwidth is 4.93 GHz（12.56～17.49 GHz）,the maximum reflection loss is-52.81 d B,and the sample thickness is 1.4 mm at the frequency of15.11 GHz.With the increase of TiO₂coating thickness,the attenuation constant of FeSiAl@TiO₂increased without affecting the impedance matching performance,especially in the high frequency range of 10～18 GHz,and TiO₂coating strengthens the attenuation ability of the material.Coating FeSiAl with proper amount of TiO₂can shift the frequency of absorbing bandwidth to low frequency by 2～3 GHz.When the thickness of FeSiAl@TiO₂ sample ranges from 1 mm to 5.5 mm,the effective absorbing bandwidth basically covers the whole C,X and Ku bands,and the improvement of absorbing performance in high frequency band is particularly prominent.（2）The coating thickness of SiO₂in FeSiAl@SiO₂is changed by changing the addition amount of tetraethl silicate.When the concentration of tetraethl silicate is 0.4mol/L The lowest reflection loss of FeSiAl@TiO₂is-33.013 d B,the maximum absorbing bandwidth is 4.59 GHz（12.22～16.81 GHz）,and the thickness of the sample is 1.8 mm.The SiO₂layer does not affect the saturation magnetization of the inner materials in the core-shell structure,but increases the coercivity of the composites.On the whole,the absorbing bandwidth of FeSiAl@TiO₂moves to high frequency compared with FeSiAl.The dielectric constant of the composites was reduced by the coated SiO₂,and the impedance matching performance of the composites was effectively improved without reducing the magnetic loss performance of FeSiAl.SiO₂coating improved the reflection loss performance of composites at middle frequency,which mainly results from the increase of eddy current loss at middle frequency and the improvement of impedance matching performance.（3）Based on FeSiAl coated with FeCo-MOF,the coating thickness was changed by changing the concentration of mixed solution;the carbonization degree of MOF could be changed by changing annealing temperature.The maximum reflection loss of FeSiAl@FeCo-MOF annealed at 600℃was-52.625 d B,and the thickness of the sample was 1.3 mm at 17.2 GHz.The saturation magnetization and coercivity of the composites increased with the increase of annealing temperature.The maximum absorption bandwidth was 5.28 GHz（13.72～18 GHz）and the sample thickness was1.4 mm.With the increase of annealing temperature,the RL of FeSiAl@FeCo-MOF was less than-40 d B at several places in the low frequency range,which shows excellent microwave absorbing performance in Ku frequency range.