Synthesis And Microwave Absorption Properties Of Fe₃O₄ Hybrid Fiber

Fe₃O₄ is a kind of traditional microwave absorbing material with a lot of research,and has the advantages of high permeability,high reflection loss.It has the shortcomings of large relative density,narrow absorption band,poor dispersion of particles,easy corrosion and poor high temperature,which limits its further application.SiO₂ has the advantages of chemical stability,easy functionalization,low dielectric constant and low conductivity.It can be used as a coating layer of Fe₃O₄ nanoparticles to shield the interaction between iron oxide nanoparticles and improve its dispersion.The unique interfacial effect between them can make the impedance more matched.Electrospinning is one of the most effective methods to prepare nanofibers at present.The method makes the solution to be spun out at high speed in high voltage electric field and obtain micro-nanofibers by solvent evaporation.Therefore,two different Fe₃O₄/SiO₂ hybrid fibers and Fe₃O₄ fiber were prepared by electrospinning.The morphology,structure,acid resistance and microwave absorbing properties of Fe₃O₄/SiO₂ hybrid fibers were analyzed.The main results are as follows:?1?Firstly,magnetic Fe₃O₄ nanoparticles were prepared by hydrothermal method.Then Fe₃O₄ nanoparticles were doped into SiO₂ fibers by electrospinning to obtain two kinds of Fe₃O₄/SiO₂ hybrid fibers with different mass fraction in the range that can be electrospun.It was found that Fe₃O₄ nanoparticles had poor dispersibility and agglomeration oucurs.The effective absorption band was narrowed to 5.9GHz.The Fe₃O₄ nanoparticles in Fe₃O₄/SiO₂ hybrid fibers are ordered in the fiber,and dispersion are improved obviously.The composite fiber has the characteristics of low density and strong acid resistance.When the matching thickness of the sample Fe₃O₄/SiO₂ hybird fiber?mass ratio 1:10?is 6mm,the reflection loss peak reaches-14.8d B at 18 GHz and the effective absorption bandwidth of <-10 dB is 11.0GHz.Further increase the content of Fe₃O₄,due to poor dispersion of particles,microwave absorbing material does not change too much.?2?Fe₃O₄ precursor fiber was prepared by electrospinning citric acid,ferric nitrate and ferrous sulfate as raw materials.After sintering,Fe₃O₄ fiber was obtained and its microwave absorbing material was analyzed.The absorption intensity was high,but the effective absorption band very narrow.On the basis of the above,Fe₃O₄/SiO₂ hybrid fibers with different mass fraction were prepared by mixture of Fe₃O₄ precursor solution with SiO₂ sol in the range that can be electrospun.It is also found that the hybrid fiber has a low density,strong acid resistance.the hybrid fiber with low Fe₃O₄ contentin the matching thickness of 6mm,the reflection loss peak at the frequency of 18 GHz to achieve-16.1d B,its <-10 dB effective absorption bandwidth reaches 11.8GHz.Further increase in Fe₃O₄ content,due to the limited capacity of SiO₂ fiber coating,so that the extra Fe₃O₄ particles adsorbed on the outer surface of the fiber,and the microwave absorbing material does not change too much.In addition,Fe₃O₄/SiO₂ hybrid fibers prepared by electrospinning on Fe₃O₄ surface coated with SiO₂ fiber have low density,strong acid resistance and large effective absorption bandwidth.