Preparation Of Fe₃O₄/Biomass Carbon Composite Materials And Their Electromagnetic Wave Absorption Properties

With the widespread application of wireless information technology,electromagnetic radiation from various electrical appliances,mobile phones,satellites,and radio and television towers that are booming has become an increasingly serious source of environmental pollution.Electromagnetic radiation will endanger human health and affect the normal operation of electronic equipment.In order to eliminat e the hazards of electromagnetic waves,electromagnetic wave absorbing materials have been widely studied.Among them,magnetite(Fe₃O₄)has attracted widespread attention due to its excellent magnetic properties,high Curie temperature,low cost and excellent saturation magnetization.However,as a single adsorbent,Fe₃O₄ has high density,easy oxidation,eddy current,large difference in dielectric constant and permeability,which limits its further application.It is suggested that carbon materials can be used as an excellent complementary material for Fe₃O₄ on account of the advantages such as light weight,good electrical conductivity,and strong dielectric loss ability.However,the current research on the raw materials of carbon materials is mostly non-renewable resources such as coal and petroleum,and the preparation methods are also relatively complicated.Therefore,biomass carbon materials have become a new research hotspot because of the unique morphology and structure,abundant trace elements,easy-to-control preparation process.Combining the advantages of Fe₃O₄ and biomass carbon materials,the excellent electromagnetic wave absorption properties can be obtained.Based on the obove reasons,the following research has been done:(1)The experiment used fish bone to prepare a three-dimensional(3D)interconnected carbon nanofiber composite Fe₃O₄/ICNF derived from biomass precursors.Synthesize ICNF with 3D interconnected frame structure through simple pyrolysis treatment and subsequent acidification process.Common Fe₃O₄ magnetic particles are used as modified materials.Through the synergistic effect of dielectric loss and magnetic loss,the performance of Fe₃O₄/ICNF is obtained.Good electromagnetic wave absorption performance.Among 20wt%paraffin filling ratio,it has a strong reflection loss(RL)of-46.2d B(5.44GHz)at a thickness of 4.11mm,and its bandwidth of less than-10d B at a thickness of 2mm ranges from 11.04GHz to 16.0GHz,and has an absorption bandwidth of 4.96GHz.(2)Eggs are cheap and easily available biomass raw materials and Na Cl was used as a hard template to obtain a porous carbon material precursor.After Fe³⁺adsorption and high temperature calcination,the biomass composite material Fe₃O₄/EPC was obtained.Through sample characterization and analysis,it is confirmed that Fe₃O₄/EPC exhibits a stable porous morphology and dispersed Fe₃O₄ particles.The strong reflection loss of Fe₃O₄/EPC at 40wt%paraffin filling ratio is-57.8 d B(7.36GHz).In addition,the effective absorption bandwidth can reach 6 GHz(11.92-17.92 GHz)at a thickness of2.03 mm,covering almost the entire Ku band.We believe that the dipole orientation and interface polarization loss,as well as the interaction between electron transmission and magnetic resonance,etc.Cooperation to improve the electromagnetic wave absorption performance of the material.