Spheroidization of Nd-Fe-B Powders by RF Induction Plasma Processing

摘要:

以不规则形的钕铁硼粉为原料，使用射频等离子体球化处理工艺，制备球形钕铁硼粉。研究了原料的加料速率和粉末粒度对粉末球化率的影响。通过扫描电子显微镜观察对比了等离子球化处理前后粉末及截面形貌，采用X射线衍射方法测试分析了球化过程中氧化物的生成。检测了球化前后粉末的松装密度及其粒度分布。结果表明：不规则形状的钕铁硼粉经等离子球化处理后其球化率可达到100%，松装密度由2.778 g/cm3提高到3.785 g/cm3，粉末流动性由43.3 s/50 g 提高到27.5 s/50 g。该粉末适用于凝胶注膜成型及注射成型

Abstract:

The present study described the synthesis of spheroidized Nd-Fe-B powders using a radio frequency (RF) inductively coupled plasma (ICP) torch with irregular feedstock materials. The effect of the power feed rate and the particle size of the feedstock material on spheroidization was analyzed. Scanning electron microscopy was used to examine the morphologies and the cross sections of plasma-processed powders. X-ray diffraction was used to analyze the oxides formed in the spheroidization processing. The loose densities and the particle size distributions of both the raw materials and the spheroidized powders were characterized. The results show that almost 100% of spheroidization percentage could be achieved. The loose density and powder flowability are enhanced greatly after plasma-treating. The loose density rises from 2.778 g/cm3 to 3.785 g/cm3. The powder flowability increases from 43.3 s/50 g to 27.5 s/50 g. Due to the good flowabitity and high loose density of the spherical powders, plasma-treated Nd-Fe-B powders have been used as the feedstock for gel-casting and injection molding