Fe-MOF衍生轻质高效雷达吸波材料的构筑及电磁特性研究

Research on the Construction and Electromagnetic Properties of Lightweightand Highly Efficient Microwave Absorption Materials Derived from Fe-MOF

现代战争对军用航空器的雷达隐身提出了极高的要求,除外形设计外,雷达吸波涂层材料是实现作战武器系统隐身的重要措施之一。作为新兴的复合损耗型吸波材料,金属有机框架(MOF)衍生碳基复合物不仅电磁衰减能力突出,也兼具轻质稳定等优势。但是现有研究中MOFs体系的选择有待系统优化,MOFs衍生物的吸波性能也有待提升。基于此,本文选择金属中心元素为Fe、配体为均苯三酸的Fe-MOF为前驱体,发现其完全分解后的产物包含结晶良好的体心立方Fe,以及部分石墨化的碳材料。得益于磁性Fe与介电碳的复合,衍生产物呈现出较高的复介电常数及一定的复磁导率,且存在较为明显的介电弛豫现象。从损耗机制上看,衍生产物以介电损耗为主,磁损耗为辅。良好的阻抗匹配为吸波性能的改善打下了基础,在1.8mm下,15.12GHz时反射损耗峰值可达-68.52dB,在1.7mm厚度下,有效吸收频带可达4.19GHz。本文不仅获得了轻质高效的航空器雷达隐身材料,也为MOF体系的系统优化指明了研究方向。

The radar stealth characteristics of military aircraft are highly required in modern war.Besides shape design,microwave absorbing coatings(MOF)play a vital role.As a novel type of synergistic loss microwave absorption material,metal-organic frameworks-derived carbon-based composites own both outstanding electromagnetic attenuation and characteristics of lightweight and stability.Nevertheless,MOFs should be selected more carefully and microwave absorption property should be improved,too.Therefore,Fe-MOF with center element of Fe and organic linker of trimesic acid has been selected as precursor,and Fe-MOF-derived product contains crystallized cubic Fe and partially graphitized carbon.Due to the combination of magnetic Fe and dielectric C,product possesses highly complex permittivity and moderate complex permeability,and strong dielectric relaxation phenomenon also occurs.As for loss mechanisms,product owns stronger dielectric loss and weaker magnetic loss.Thanks to the balance between dielectric and magnetic loss,Fe/C product owns RL peak value of-68.52dB at thickness of 1.8mm and effective absorption bandwidth of 4.19GHz at thickness of 1.7mm.This paper not only provides highly efficient microwave absorption materials for aircraft,but also points out directions of optimization research on MOF-derived materials.