Preparation And Microwave Absorption Properties Of Polyhedron Fe-based Composites

In this paper,The polyhedral micro/nano-Fe powders with shape anisotropy were successfully prepared by solvothermal method and DC arc method.The microstruture,morphology and composition were researched by X-ray diffractometer（XRD）,scanning electron microscope（SEM）and X-ray photoelectron spectroscopy analysis（XPS）.At the same time,the effect of different contents of absorber on the absorbing performance was detail characterized by Vector network analyzer.The results show that the size of polyhedronα-Fe powder prepared by solvothermal method is about 300nm,and the relationship between mass fraction and microwave absorption performance is nonlinear enhancement.The maximum reflection loss achieved-48.90dB at 8.78GHz with the coating thickness of 2mm while the mass fraction ofα-Fe powder is 50wt%.The bandwidth with reflection loss below-10dB ranges from 2.04GHz to 18GHz by absorbing layer thickness of 1.28-7.00mm chosen.The Fe nanoparticles with different shapes were obtained by controlling the Al content in the solid solution target FeAl alloy under the same atmosphere（hydrogen,argon）and the same current 50-60A by the DC arc method.The prepared samples were spherical,polyhedral,and spherical,while the percentages of Al in master alloy FeAl were 0wt%,3wt%,and 5wt%,respectively.The studies have reveal that a small amount of Al keeps the Fe nanoparticle in the body-centered cubic phase and assumes a polyhedral shape.In the Fe Al master alloy,while the Al content reaches 5wt%,the as-prepared samplers generate the Fe Al alloy phase besides body-centered cubic Fe phase and shape of samplers is in a spherical.The size of polyhedron Fe/Fe Ox-Al₂O₃（Al content 3wt%）and spherical Fe/FeOx（Al content 0wt%）nanoparticles is approximately 20-40nm.At the same mass fraction,when the reflection loss is less than-10dB,the polyhedron Fe/FeOx-Al₂O₃ has a larger bandwidth than the spherical Fe/FeOx,and the relationship between mass fraction and microwave absorption performance is nonlinear enhancement.And the maximum reflection loss of the polyhedron Fe/FeOx-Al₂O₃ is larger than that of the spherical Fe/FeOx,and the relationship between mass fraction and microwave absorption performance is nonlinear enhancement.When the mass fraction of polyhedron Fe/FeOx-Al₂O₃ is 50wt%,the reflection loss achieved-61.66dB at 7.28GHz with the coating thickness of 2.90mm.The frequency range of the reflection loss RL<-10dB is2.5-18GHz and the corresponding coating thickness range is 1.26-6.60mm.The studies have shown that the maximum reflection loss,resonance frequency,and absorption bandwidth of the microwave absorption properties depend on the mass fraction of the absorbent in the paraffin matrix and also on the shape of the absorbent.