Al含量对MnAl粉体微波吸收特性的影响

Effect of Al Content on Microwave Absorbing Properties of MnAl Powder

摘要:

采用高能球磨和热处理工艺制备了MnAl合金粉体，使用SEM、XRD和网络矢量分析仪研究Al含量对MnAl合金粉体组织结构和微波吸收特性的影响。结果表明：随Al含量的增加，MnAl合金粉体中Al0.89Mn1.11、β-Mn和Al2Mn3含量降低、Al8Mn5含量升高，使粉体磁损耗和介电损耗增加、共振频率向低频移动、吸收峰数增加。吸波层厚度为2.0 mm时, Mn40Al60样品在12.2 GHz频率处有最大吸收峰，其反射率最小值为–26.5 dB，具有较好的频宽效果。MnAl粉体对电磁波的吸波机理包括吸波涂层内的损耗以及前后界面反射电磁波在前界面处的干涉损耗

Abstract:

The MnAl alloy powder was prepared by high-energy ball milling and heat treatment process. Effect of Al content on the microstructure and microwave absorbing properties of MnAl powder were investigated with the help of scanning electron microscope (SEM), X-ray diffraction (XRD) and network vector analyzer. The results show that with the increase of Al content, Al0.89Mn1.11, β-Mn and Al2Mn3 contents in MnAl alloy powder decrease while the Al8Mn5 content increases; as a result, the powder magnetic loss and dielectric loss increase, resonance frequency moves to the low frequency, and more absorption peaks appear. When absorbing layer thickness is 2.0 mm, the Mn40Al60 sample has a maximum absorption peak at 12.2 GHz frequency, the reflectivity minimum is –26.5 dB, showing a better bandwidth effect. MnAl powder absorbing mechanism of electromagnetic wave includes the electromagnetic loss in the inner of the absorber and the interference loss between the reflection waves from the back interface and the front interface