铁氧体-铁磁金属包覆短碳纤维复合材料的可控制备与电磁波吸收机理研究

The development of electromagnetic wave shielding material with wide band, high absorption ability and low density is the key point in the field of electromagnetic absorbing. Short carbon fiber has been widely concerned because of its advantages of low density and shape anisotropy. However, the permeability of short carbon fiber based composite material is relatively low, which leads to the electromagnetic impedance mismatch, and makes low-absorption and high-reflection electromagnetic shielding property. The previous study demonstrated that the composite with electrical double-shell structure showed enhanced interfacial polarization， which optimized impedance matching. In this project, short carbon fiber composite material, coated by ferrite-ferromagnetic metal double shells, was fabricated through the combination of chemical plating and self assembling methods. The mechanism of the electromagnetic wave absorption modulated by microstructure was studied. Based on the electromagnetic parameters-frequency response, the impedance matching model of magnetic double-shell structure was established, and the mechanism of shape anisotropy on the polarization and magnetization response of electromagnetic wave was expounded. Through the Matlab simulation, the effects of shape anisotropy and multiple interface structure on electromagnetic wave absorption peak and bandwidth were revealed. The results obtained established the foundation for the application of ferrite-ferromagnetic metal coated short carbon fiber composites in the electromagnetic wave absorption fields.

发展“频带宽、吸收强、密度小”的电磁波屏蔽材料是吸波领域的研究重点。短碳纤维由于其具有密度小和形状各向异性的优点，被广泛关注。然而短碳纤维基复合吸波材料的磁导率相对较低，导致其阻抗失配，使电磁屏蔽呈现低吸收、高反射的特点。前期研究工作发现，电性双壳层结构具有增强的界面极化效应，可以优化阻抗匹配。本项目据此提出采用铁氧体-铁磁金属作为外壳层，将化学镀和自组装法相结合，制备磁性双壳层包覆短碳纤维复合材料，进行复合材料的微观结构调控电磁波吸收的机理研究。从电磁参数-频率响应关系出发，建立磁性双壳层结构的阻抗匹配模型，阐明形状各向异性对吸波材料的极化-磁化响应的作用机制。通过Matlab模拟计算，揭示形状各向异性和多重界面结构对电磁波吸收峰值和带宽的影响过程，为铁氧体-铁磁金属包覆短碳纤维新型复合吸波材料在电磁屏蔽领域的应用奠定基础。

针对由电磁辐射造成的社会危害，研究如何抗电磁干扰和防护电磁信息泄露具有紧迫性和必要性。设计吸收频带宽、吸收效率高且自身密度低的电磁波吸收材料以消除或减少电磁辐射，成为材料学和电磁兼容领域的重要课题。前期的探索工作表明，材料的微观形貌、界面结构等因素对电磁波吸收有调控作用，这对电磁辐射问题的解决具有重要意义。.本项目以铁氧体-铁磁金属作为外壳层、棒状短碳纤维作为支撑骨架，制备了磁性双壳层包覆的短碳纤维复合材料(C/Ni/Fe3O4)；C/Ni/Fe3O4在复介电系数和复磁导率-频率响应曲线上新出现了共振峰，这主要是由于其双壳层结构具有增强的界面效应以及增强的各向异性场所致；电损耗因子/磁损耗因子-频率响应和Delta函数表明，双壳层结构可以有效改善阻抗匹配特性；C/Ni/Fe3O4复合材料最大反射损耗可达-31 dB，并在12.8 GHz和15.0 GHz处出现了双重共振吸收峰，这与磁损耗和介电损耗谱中的峰值位置一致，也与Delta函数中阻抗匹配最优区域接近。因此，这种电磁波吸收性能的增强是由阻抗匹配优化和双壳层界面效应共同作用所致。以上工作为今后进一步揭示双壳层复合材料电磁波吸收的物理机制和开发新型微波吸收复合材料打下了基础。