基于电泳沉积Al及其晶界扩散优化的烧结NdFeB磁体的微观结构和磁性能

Microstructure and Magnetic Properties of Sintered NdFeB Magnets Optimized by Electrophoretic Deposition of Al and Its Grain Boundary Diffusion

采用电泳沉积(EPD)法在烧结NdFeB磁体表面沉积Al膜,研究了不同电泳电压和沉积时间对沉积Al膜的影响,在此基础之上,探究了不同晶界扩散工艺对磁体微观组织和磁性能的影响。结果表明:最佳的电泳工艺为90 V/30 s,此时膜层与磁体结合良好,且厚度均匀适中。晶界扩散工艺为500℃/1 h时,磁体获得了最佳的综合磁性能,其矫顽力、剩磁和最大磁能积为953 kA/m、1.41 T和342 kJ/m^3,分别提升了30.2%、0.7%和11.4%。微观结构和成分分析发现,晶界扩散后,晶间形成了更为平直光滑的富稀土相薄层,有助于降低退磁场和增强磁隔离效应,最终导致矫顽力的提高。

An Al film was deposited on the surface of sintered NdFeB magnets by electrophoretic deposition(EPD).It is found that different EPD voltages and times have a great influence on the deposition of Al films.We also investigated the effects of different grain boundary diffusion processes on the microstructure and magnetic properties of the magnet.The results show that the best EPD process is 90 V/30 s.At this time,the combination of the film and the magnet is well,and the thickness is even and moderate.When the grain boundary diffusion process is 500°C/1 h,the magnet obtains the best comprehensive magnetic properties,and its coercivity,remanence and maximum magnetic energy product are 953 kA/m,1.41 T and 342 kJ/m^3,respectively,which increases by 30.2%.0.7%and 11.4%,respectively.Through microstructure and composition analysis,it is found that after the grain boundary diffusion,a flatter and smoother rare earth-rich phase thin layer forms between the crystals,which helps to reduce the demagnetizing field and enhance the magnetic isolation effect,and finally leads to the improvement of coercive.