Construction Of Absorbing Materials With Carbon-coated Multi-stage Ferromagnetic Particles

Absorbing materials are a type of materials that dissipate incident electromagnetic waves by converting electromagnetic energy into heat and other forms of energy through dielectric losses and magnetic losses.It is widely used in the fields of anti-electromagnetic interference,microwave dark room,stealth aircraft and so on.Among them,The carbon-coated ferromagnetic particle composite absorbing materials have both dielectric loss and magnetic loss mechanisms,and have attracted more and more attention.Composite absorbing materials need to have a well-designed morphology and rich interfaces to balance impedance matching and attenuation.Therefore,carbon-coated ferromagnetic particle composite materials with different structures were constructed in this paper,and the influence of various factors on the morphology,structure and microwave absorption properties of the materials during the reaction process was studied.The main contents of this study are:Firstly,Fe@Void@C-N absorbing material was designed and synthesized.The Fe₃O₄@SiO₂@APF/RF was synthesized by solvothermal method,hydrothermal method,etc.,and Fe@Void@C-N composite material was synthesized by alkali etching SiO₂ shell after heat treatment.The effects of preparation experimental conditions such as the amount of resin monomer,TEOS,alkali etching conditions,heat treatment temperature,etc.on the morphology structure,intermediate layer structure,carbon layer thickness and microwave absorption properties of Fe@Void@C-N composites were studied.The research shows that under the conditions of 200 mg of resin,0.2 mL of TEOS,800℃heat treatment temperature and 50℃alkali treatment,the electromagnetic performance of the composite material reaches a minimum RL value of-54.92 dB at a thickness of 4.59 mm and a frequency of4.00 GHz,and the qualified bandwidth with a thickness in the range of 1-5 mm is 14.72GHz.Secondly,the hollow Fe@SiO₂/Co/C-N absorber was designed and synthesized.The precursor Fe₃O₄@xSiO₂-yCo O@PDA was synthesized by solvothermal method,Stober method,polymerization reaction etc.The hollow Fe@SiO₂/Co/C-N composite material was obtained after heat treatment.The sheet-like SiO₂ in the material structure has a limited region,the effect is to make the metallic Co inlaid therein to avoid agglomeration.At the same time,the sheet-like structure is beneficial to the multiple reflection of electromagnetic waves and improves the attenuation ability.The carbon material can not only improve the dielectric loss of the material,but also stabilize the structural frame.By adjusting the experimental method,heat treatment temperature and other factors to optimize the structure and absorbing properties of the material.Studies have shown that the Fe₃O₄@xSiO₂-yCo O composite material synthesized by the oil bath stirring method has a uniform structure.The best electromagnetic performance of the composite material obtained through a reasonable heat treatment process is shown to reach a minimum RL value of-62.31 dB at a thickness of 2.05 mm and a frequency of 16.96 GHz,the qualified bandwidth in the thickness range of 1-5 mm is 13.28 GHz.