原位选择氮化法制备铁基软磁粉芯与吸波材料及其结构与性能调控研究

Surface insulating modification of soft magnetic alloy powders is an effective way to reduce the core loss of corresponding powder cores and improve the impedance matching of corresponding microwave absorbing materials. However, it is difficult to produce insulation layer on the surface of the magnetic powder with excellent stability and heat conductivity, which largely hindered the application and development of soft magnetic alloy powders. Therefore, the applicants provide a novel method of preparing homogeneous nano-scale nitrides/oxides insulation layer on the surface of Al-contained or Cr-contained Fe-based magnetic powders by means of in situ surface selective nitridation to produce soft magnetic cores with low loss and microwave absorbing materials with excellent impedance matching. In this project, the effects of selective nitriding and high temperature annealing process on the microstructures and the physical properties of Al-contained or Cr-contained Fe-based powders and corresponding powder cores and microwave absorbing materials will be studied, and the associated physical mechanism of “selective nitridation-microstructures of magnetic powders-high temperature annealing-microstructures of powder cores-physical properties” and “selective nitridation-microstructures of flake magnetic powders-physical properties” will be established. The selective nitridation behavior of Al-contained or Cr-contained Fe-based magnetic powder, as well as the formation mechanism of insulating layer will be revealed. The effects of the nitrided magnetic powders on the microstructures and electromagnetic properties of the corresponding magnetic cores and microwave absorbing materials will be clarified. These researches will help providing theoretical basis for developing novel surface modification method of magnetic powders and preparing magnetic cores and microwave absorbing materials with high quality.

对金属软磁粉进行表面绝缘改性是降低其磁粉芯电磁损耗和提高其微波吸收材料阻抗匹配的有效方法，但目前的包覆工艺难以获得兼具高稳定性和热导性的绝缘膜，极大地阻碍了其应用与发展。为此，申请者提出采用选择氮化法对含Al或Cr的Fe基磁粉进行表面改性，在其表面原位生成与界面结合力强且具有优异稳定性和导热性的氮化物/氧化物纳米绝缘膜，以期制备出低损耗磁粉芯和高阻抗匹配吸波材料的全新思路。本课题拟重点研究选择性氮化处理和高温退火工艺对含Al或Cr的Fe基磁粉及其磁粉芯和吸波材料结构与性能的影响机制，建立“选择氮化-磁粉微观结构-高温退火-磁粉芯微观结构-性能”和“选择氮化-片状磁粉微观结构-吸波材料性能”物理关联，弄清磁粉表面选择性氮化行为，揭示其表面绝缘膜生成机制，阐明表面改性后的磁粉对磁粉芯和吸波材料微观结构与性能的影响规律与机理，以期发展磁粉表面改性新方法并为高品质磁粉芯和吸波材料制备提供理论指导。

对金属软磁粉进行表面绝缘改性是降低其磁粉芯电磁损耗的有效方法，但目前的包覆工艺难以获得兼具高稳定性和高热导性的绝缘膜，极大地阻碍了其应用与发展。为此，申请者采用选择氮化法对Fe基磁粉进行表面改性，在其表面原位生成与界面结合力强且具有优异稳定性和导热性的氮化物/氧化物纳米绝缘膜，制备出低损耗磁粉芯。本课题重点研究了选择性氮化处理和高温退火工艺对FeSiAl和FeSiCr等磁粉及其磁粉芯结构与性能的影响机制，建立“选择氮化-磁粉微观结构-高温退火-磁粉芯微观结构-性能”物理关联，弄清了磁粉表面选择性氮化行为，揭示了其表面绝缘膜生成机制，阐明了表面改性后的磁粉对磁粉芯微观结构与性能的影响规律与机理。此外，由于铁氧体同时具备较高电阻率和磁导率，因此还利用原位溶胶凝胶自蔓延和球磨法制备了以铁氧体为包覆层的FeSiAl和FeSiCr基复合磁粉芯，研究了制备工艺对其结构与性能的影响及机理。