铁氧体含量对Fe/NiZnFe_2O_4铁粉芯磁性能的影响

Effect of ferrite content on magnetic properties of Fe/NiZnFe_2O_4 powder core

铁粉芯是一种具有良好软磁特性和频率特性的材料。采用放电等离子烧结(SPS)的方法制备了镍锌铁氧体包覆还原铁粉的铁粉芯,研究了铁氧体含量对铁粉芯的包覆效果和磁性能的影响。结果表明,适量的铁氧体含量有利于Fe/NiZnFe_2O_4铁粉芯的包覆和磁性能,铁氧体含量为8%时,可较好的包覆在铁粉颗粒表面,制得的磁粉芯性能最佳,具有较高的振幅磁导率μa,较低的矫顽力Hc、视在功率Ss和损耗Ps。对其损耗进一步分析发现,当频率f≤30kHz时,涡流损耗Pe占总损耗的比例<40%,磁滞损耗Ph是总损耗的主要来源;当频率f>70kHz时,Pe所占的比例>60%,这一结果对于指导磁粉芯的应用提供了理论基础,也为进一步降低铁粉芯的损耗指明了努力的方向。

The iron powder core is a kind of materials with good soft magnetic properties and frequency characteristics. In this paper, the iron powder core of nickel-zinc ferrite coated reduced iron powder was prepared by spark plasma sintering (SPS) method. The consequence of ferrite content on the coating effect and magnetic properties of the iron powder core was investigated. The results show that the suitable ferrite content was conducive to coating effect and magnetic properties of Fe/NiZnFe2O4 powder core. When the ferrite content was 8%, it could be coated on the surface of powder particles and a good magnetic performance, such as high amplitude permeability μa, low coercive force Hc, apparent power Ss and loss Ps, was obtained. Further analysis of the loss shows that when the frequency f was less than 30 kHz, the eddy loss current Pe accounted for less than 40% of the total loss. When the frequency f was higher than 70 kHz, the proportion of P ewas more than 60%.The result provides a theroical basis which has made a great contribution to guiding the application of the magnetic powder core, and also indicates the direction of efforts to reduce the loss.