铁氧体/芦苇秆炭复合材料的制备与吸波性能

Preparation and microwave absorption properties of ferrite/reed charcoal composites

为了解决铁氧体吸波材料密度大、吸收带宽窄等问题,以芦苇茎秆为原料,采用常温浸渍及高温原位生长法制备了铁氧体/芦苇秆炭(Ferrite/RC,FRC)复合材料,通过调节碳化温度调控复合材料的电磁特性和电磁波吸收性能。SEM、TEM、XRD、VSM及VNA等结果表明:Ferrite/RC复合材料保留了芦苇秆天然的三维蜂窝状网络结构,Fe_(3)O_(4)及铁纳米颗粒均匀分布在芦苇秆碳壁与孔道中;提升碳化温度(650~690℃)可增大复合材料的电导率与介电损耗能力,但温度过高会导致材料阻抗失配从而降低电磁衰减能力。碳化温度为670℃时制备的复合材料(FRC-670)吸波性能最佳,它在匹配厚度仅为1.7 mm时反射损耗达到−45.7 dB,对应有效吸收带宽为3.4 GHz;在厚度为2 mm时有效吸收带宽为5.7 GHz(12.1~17.8 GHz)。其主要的电磁波衰减机制源于复合材料良好的电导损耗、极化弛豫损耗以及电损耗与磁损耗的协同作用。铁氧体/芦苇秆炭复合材料优异的吸波性能在电磁波吸收领域具有良好前景,可促进芦苇资源的高值化与功能化应用。

In order to solve the problems of high density and narrow absorption bandwidth of ferrite absorbing materials,the ferrite/reed charcoal(Ferrite/RC,FRC)composites were prepared from reed stalks by impregnation and high temperature in-situ growth methods.The electromagnetic characteristics and electromagnetic wave absorption properties of the composites were controlled by tailoring the carbonization temperature.The results of SEM,TEM,XRD,VSM and VNA show that the Ferrite/RC composites retain the natural three-dimensional honeycomb network structures of the reed stalks,and Fe_(3)O_(4)and iron nanoparticles are uniformly distributed in the charcoal wall and pores of the reed stem;Raising the carbonization temperature(650-690℃)can increase the conductivity and dielectric loss ability of composites,but excessive temperature can lead to impedance mismatch of the material and reduce its electromagnetic attenuation ability.The composites prepared at a carbonization temperature of 670℃exhibit the best absorption performance,with a reflection loss of−45.7 dB at a thickness of only 1.7 mm and an effective absorption bandwidth of 5.7 GHz(12.1-17.8 GHz)at a thickness of 2 mm,which is attributed to the good conductivity loss,polarization relaxation,and the synergistic effect of electrical and magnetic losses of composite materials.The excellent absorption performance of Ferrite/RC composites has good prospects in the field of electromagnetic wave absorption,which can promote the high-value and functional application of reed resources.