兰州大学机构库 >物理科学与技术学院
易面各向异性磁粉复合材料微波吸收性能的研究
Alternative TitleMicrowave absorption properties of the easy-plane anisotropy powder/matrix composites
韩瑞
Thesis Advisor李发伸
2013-05-25
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword易面各向异性 复数磁导率 复数介电常数 微波吸收性能 四分之一波长 前后界面反射
Abstract无论是电磁屏蔽还是抗电磁干扰,都要求吸波体具有“薄,轻,宽,强”即:“厚度薄,质量轻,吸收频带宽,吸波性能强”的特点。基于四分之一波长模型及阻抗匹配理论,对于金属磁粉吸波体,高的复数磁导率及适中的介电常数是满足上面要求的必要条件。依据双各向异性模型,具有易面各向异性的材料可以突破Snoek极限的限制,使得样品在微波段获得高的复数磁导率,有望成为新一代吸波体的设计理念。 在上述理论模型的指导下,我们从实验上制备了具有易面形状各向异性的羰基铁微粉以及具有易面磁晶各向异性的稀土-3d过渡族金属间化合物。研究了易面各向异性材料的高频磁电特性及微波吸收性能。研究的主要内容和结果如下: 1. 材料的选择; 2. 易面各向异性羰基铁粉最佳制备条件; 3. 磁场旋转取向改进了样品的高频磁性; 4. 易面型磁粉的表面改性,进一步优化了样品的微波吸收性能; 5. 易面磁晶各向异性磁粉微波吸收性能的研究; 6. 建立界面反射模型,应用界面反射模型,通过前界面改进对样品的微波吸收性能进行了进一步的优化。
Other AbstractTo solve the problem of electromagnetic interference and electromagnetic compatibility, it is necessary to exploit a type of microwave absorption materials with thinner thickness, lighter weight, wider frequency band of microwave loss and more intensity of the microwave absorption. Complex permittivity and permeability of the absorbers play key roles in determining the absorption properties. According to the quarter-wavelength model, for metal magnetic absorbers, higher permeability and appropriate permittivity values are needed to satisfy the above demands. According to the bianisotropy theory, the easy-plane anisotropy materials can exceed the limit of the Snoek’s limit and obtain a higher permeability in higher frequency range. The shape planar anisotropy carbonyl-iron powder and magnetocrystalline easy-plane anisotropy rare-earth 3d transition intermetallics have been prepared based on the bianisotropy theory. The dependence of the complex permeability, permittivity and the microwave absorption properties of these materials were investigatedThe details and results of our research are listed as follows: 1. The choice of the easy-plane anisotropy materials 2. To optimize the ball milling method. 3. The easy-plane anisotropy canbonyl-iron/paraffin composite was oriented in an external magnetic field. The permeability of composite has an increasing factor of 0.2-0.3 than the nonoriented one. 4. To reduce the permittivity of the easy-plane anisotropy carbonyl-iron particles, the surface of the particles were coated with a thin isolated layer. Compared with the uncoated PACI particles, the permittivity of the composite decreased dramatically, and hence a dramatic enhancement of reflection loss (RL) was obtained in quasimicrowave band. 5. A new easy-plane anisotropy Ce2Fe17N3-δ compound and Sm2Fe14B nanocrystal as electromagnetic absorption materials were prepared by melt spinning method. 6. The matching frequency and the intensity of reflection loss for the absorbers obey the quarter-wavelength model and the reflective loss model. According to the results, coating a conductor layer in the front layer of the absorber can change the intensity of the reflective wave from the absorber layer interface and improve the microwave absorption properties of the absorbers.
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229088
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
韩瑞. 易面各向异性磁粉复合材料微波吸收性能的研究[D]. 兰州. 兰州大学,2013.
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