粉末细化对钕铁硼磁性能的影响

Effect of powder size refinement on magnetic properties in Nd-Fe-B sintered magnet

通过调整粉末制备工艺研究了粉末粒度的细化对钕铁硼磁体结构及性能的影响。结果发现,当粉末表面积平均粒度(SMD)从2.8μm降低至2.3μm时,出粉效率降至原有水平的40%左右,粉末均匀度逐步提升,而烧结后磁体的氧质量分数从1000×10^-6提高至2700×10^-6左右。通过微观结构观察发现,采用细化粉末烧结后富钕相分布更加均匀稠密,烧结后晶粒尺寸分布在3~8μm之间。通过粉末细化,在成分不变的情况下,磁体的矫顽力提升了175kA/m。

The effect of powder size refinement on microstructure and magnetic properties was investigated by optimizing jet-milling process.It was discovered that,when the average particle size(sauter mean diameter)decreased from 2.8μm to 2.3μm,the milling efficiency decreased to 40%of original level,the homogeneity of the particles distribution was improved gradually and the oxygen content of the sintered magnet was increased from 1000×10^-6 to 2700×10^-6.Microstructure observation result showed that,the Nd-rich distributed more homogeneously and dense in the magnet sintered with refined powder,and the corresponding grain size distributed in the range between3-8μm.With the powder refinement process,the coercivity of the magnet increased by 175 kA/m while maintaining the same nominal composition.