不同形貌羰基铁的复合对电磁特性及吸波性能的影响

目的增强羰基铁的低频吸波性能,掌握吸收峰频率的调控方法。方法将球形羰基铁与片状羰基铁混合,制作复合材料。通过扫描电子显微镜对两种羰基铁的微观形貌进行分析。通过矢量网络分析仪测量5种质量配比下(3∶1、2∶1、1∶1、1∶2、1∶3)羰基铁复合材料的复介电常数和复磁导率,分析不同形貌羰基铁的复合对电磁特性的影响。同时分析不同配比羰基铁复合材料的吸波性能。结果随着球形羰基铁加入比例的提高,复合材料的复介电常数实部和虚部均逐步下降。羰基铁复合材料的复磁导率实部整体变化不大,虚部呈下降趋势。当片状羰基铁和球形羰基铁质量比为1∶2时,在3.08 GHz处最大吸波性能为20.2 dB,有效吸波带宽(反射率损耗不大于8 dB)为2.43 GHz。结论球形羰基铁的加入可以有效调控复合材料的吸收峰在低频范围内定向移动,增强1~4 GHz范围内的低频吸波强度,扩宽有效吸波带宽。球形羰基铁的加入,降低了片状羰基铁的介电常数,复合材料的电磁阻抗匹配条件得到优化,电磁损耗耦合效应增强,从而提升了该复合材料的吸波性能。

Electromagnetic Characteristics and Microwave Absorption Properties of Carbonyl Iron Composites with Different Morphologies

The work aims to improve the microwave absorption performance of carbonyl iron at low frequency and master the method of controlling the frequency of absorption peak.The spherical carbonyl iron was mixed with sheet carbonyl iron to prepare composites.The morphologies of two types of carbonyl iron were analyzed by SEM.The complex permittivity and complex permeability of carbonyl iron composites at different mass ratios(3∶1,2∶1,1∶1,1∶2,1∶3)were measured by vector network analyzer to study the effect of carbonyl iron composites with different morphologies on electro magnetic characteristics and analyze the microwave absorption performance of the composites at different mass ratios.With the increase of the proportion of spherical carbonyl iron,the real imaginary parts of complex permittivity in the composites decreased gradually.The real part of complex permeability in carbonyl iron composites had a small change while the imaginary part decreased.When the mass ratio between the sheet carbonyl iron with spherical carbonyl iron was 1∶2,the minimum reflection loss reached?20.2 dB at 3.08 GHz.The effective absorption bandwidth for RL≤?8 dB reached 2.43 GHz at low frequency.The addition of spherical carbonyl iron into sheet carbonyl iron can control movement of absorption peak at low frequency,improve the microwave absorption within 1~4 GHz and broad the effective absorption bandwidth.The addition of spherical carbonyl iron also decreases the complex permittivity of sheet carbonyl iron,which can make the impedance matching condition better and improve the electromagnetic loss coupling effect,thus enhancing the microwave absorption performance.