纳米Al_2O_3掺杂对NdFeB磁体磁性能和电阻率的影响

Effect of nano-Al_2O_3 doping on the magnetic properties and resistivity of NdFeB magnets

NdFeB磁体的电阻率很低,在大动力牵引机车电机工作条件下,涡流损耗明显,使工作温度过高,造成永磁体失磁,降低电机性能。通过高电阻率的纳米Al2O3掺杂来提高电阻率。采用NdFeB快淬粉,通过热压、热变形技术制备了不同质量分数纳米Al2O3掺杂的NdFeB磁体,研究了纳米Al2O3掺杂对NdFeB磁体的热压致密性、磁性能和电性能的影响。结果表明,随着Al2O3质量分数的提高,热压密度先增加后降低,电阻率逐渐增大,当Al2O3质量分数为1.5wt%时,电阻率增大了13%;但是,纳米Al2O3掺杂对磁性能影响很大,随着Al2O3含量的增加,矫顽力和剩磁都急剧下降。

Eddy current loss is obvious in NdFeB permanent magnet motors for high power traction locomotive because of very low resistivity of NdFeB permanent magnet material. The temperature rise resulting from eddy current loss under this condition will make the permanent magnet demagnetized, which lower the property of electrical motor. This paper focuses on the resistance improvement of the NdFeB magnets by doping nano-A1203. NdFeB magnets with different contents of A1203 were prepared by hot pressing and hot deforming using the quenched NdFeB powders. Effect of nano-A1203 doping on the density of the hot pressed compaction and microstructures, magnetic and electrical properties of the samples have been discussed. The results show that hot pressing density first increases and then decreases with increasing mass fraction of A1203 while the resistivity increases gradually. When the mass fraction of A1203 is 1.5wt%, the resistivity increases by 13%. However, the results also show that the Hcj and Br decrease with the increase of the content of nano-A1203.