射频等离子体球化处理氢化钕铁硼粉末

摘要

Spherical powders were prepared by radio frequency (RF) plasma with irregular hydrogenated Nd-Fe-B powders. The morphology, elemental distribution, phase composition and particle size distribution of the powders before and after spheroidization were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and laser micron sizer (LMS). The results show that dehydrogenation decomposition and spheroidization processing of the irregular hydrogenated Nd-Fe-B powders can be finished with one step in the plasma. Powders after plasma processing have good spherical shape and dispersity, and their spheroidization ratio is almost 100%. The particle size distribution becomes narrow after spheroidizing, and the average size decreases slightly. The spherical powders consist of Nd2Fe17(B) andα-Fe phases. The analysis of element distribution by EDS indicates that slight element segregation exists on the cross section of powders after plasma processing. The spheroidization ratio gradually decreases with increasing the carrier gas flow rate. Results of numerical simulation through FLUENT software show that change of carrier gas flow rate has a great influence on the temperature field of plasma torch.%利用氩气射频等离子体球化处理形状不规则的氢化钕铁硼粉末。采用扫描电子显微镜、能谱仪、X线衍射仪、激光粒度分析仪对射频等离子体处理前后粉末颗粒的形貌、元素分布、物相、粒度分布进行测试和分析。结果表明：不规则形状的氢化钕铁硼粉末的脱氢分解和球化过程可在等离子体中一步完成，得到球形度高、分散性好、球化率接近100%的球形粉末。球形粉末较氢化钕铁硼原料粉末，粒度分布明显变窄，平均粒度稍有减小。球形粉末的相组成主要为Nd2Fe17(B)和α-Fe。元素分布测试表明，经射频等离子体处理获得的球形粉末有轻微的元素偏析。随载气流量增加，粉末的球化率降低。结合FLUENT数值模拟分析得出载气流量的变化对等离子体炬的温度场有很大影响。