Wan Lirui, Sun Xiaoran, Li Jiechao, Wu Shen
Institute of Electromechanical Engineering and Intelligent Manufacturing, Zhengzhou Vocational College of Information Technology, Zhengzhou 450008, China.
Institute of Mechanical and Electrical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China.
Materials (Basel). 2024 Aug 14;17(16):4039. doi: 10.3390/ma17164039.
Optimizing the interface between a magnetic powder matrix and an oxide-insulating layer is an effective method to improve the permeability and lower eddy current loss of iron-based soft magnetic composites. In this study, in order to improve the bonding strength of the substrate and insulation layer, soft magnetic composites were prepared by pressing and heat treating with reduced iron powder as a magnetic matrix, high-temperature MgO nanoparticles as insulating coating, and phenolic resin as an adhesive. The effects of MgO content on the microstructure and magnetic properties of the composites were investigated. The results of a scanning electron microscopy and an energy-dispersive spectrometer analysis corroborate that the results obtained regarding the frequency characteristics and the resistivity of the iron powder agree with the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis and confirm their improvement by the presence of an insulating layer of MgO. The resistivity of the sample coated with 4 wt.% MgO is nearly 45 times higher than that of the uncoated sample under the same conditions. The MgO-insulating film formed on the surface of iron powder makes the coated sample have low effective grain size, high resistivity, and low magnetic loss at a high frequency. At 1 kHz, the magnetic loss of the 4 wt.% MgO-coated sample is reduced by 77.3%, and the magnetic loss is only 5.8% compared with the uncoated sample at 50 kHz. This magnetic loss separation study shows that the addition of MgO insulation material can effectively reduce the eddy current loss of the magnetic powder core. The 4 wt.% MgO-coated sample has the lowest hysteresis loss factor and relatively low eddy current loss factor, so it can be determined that the addition of 4 wt.% MgO is the optimum content to attain a low magnetic loss.
优化磁粉基体与氧化物绝缘层之间的界面是提高铁基软磁复合材料磁导率和降低涡流损耗的有效方法。在本研究中，为了提高基体与绝缘层的结合强度，以还原铁粉为磁基体、高温MgO纳米颗粒为绝缘涂层、酚醛树脂为粘结剂，通过压制和热处理制备了软磁复合材料。研究了MgO含量对复合材料微观结构和磁性能的影响。扫描电子显微镜和能谱分析仪的分析结果证实，关于铁粉频率特性和电阻率的结果与扫描电子显微镜（SEM）和能谱分析仪（EDS）的分析结果一致，并证实了MgO绝缘层的存在使其得到改善。在相同条件下，涂覆4 wt.%MgO的样品的电阻率比未涂覆样品的电阻率高出近45倍。铁粉表面形成的MgO绝缘膜使涂覆样品具有低有效晶粒尺寸、高电阻率和高频下的低磁损耗。在1 kHz时，涂覆4 wt.%MgO的样品的磁损耗降低了77.3%，在50 kHz时与未涂覆样品相比磁损耗仅为5.8%。该磁损耗分离研究表明，添加MgO绝缘材料可有效降低磁粉芯的涡流损耗。涂覆4 wt.%MgO的样品具有最低的磁滞损耗因子和相对较低的涡流损耗因子，因此可以确定添加4 wt.%MgO是实现低磁损耗的最佳含量。
