NdFeB Powder Making Process
Hydrogen Decrepitation (HD) Process for Melt-Spun NdFeB Flakes
The hydrogen decrepitation process is applied to pre-crushed melt-spun NdFeB fragments (typically 5-20mm in size). When exposed to hydrogen gas at 200-600°C, the H₂ penetrates the fine-grained structure of these rapidly solidified fragments, causing intergranular fracture. The melt-spun flakes exhibit superior HD efficiency compared to conventional cast ingots due to their homogeneous microstructure, typically requiring only 0.1-1.0MPa hydrogen pressure. Process control focuses on maintaining high-purity hydrogen (>99.99%), implementing controlled heating profiles, and minimizing oxygen uptake. The output is friable particles (0.1-1mm) ideal for subsequent milling.
Jet Milling Process for NdFeB Powder
The jet milling process serves as the crucial size-reduction step to produce fine NdFeB powder (3-5μm) from the HD-treated melt-spun flakes. In this enclosed system, the hydrogen-decrepitated particles are accelerated by supersonic nitrogen streams (0.6-1.0MPa) to achieve interparticle collision and fragmentation. The unique porous structure of HD-treated melt-spun flakes significantly reduces energy consumption during jet milling compared to conventional cast materials. Process optimization focuses on three key aspects: balancing inlet pressure and classifier wheel speed (typically 3000-6000rpm), maintaining ultra-low oxygen levels, and achieving optimal particle size distribution. Powder flow characteristics must also be carefully controlled to ensure subsequent processing performance. This advanced milling technology produces NdFeB powder with exceptional quality, meeting the stringent requirements for high-performance permanent magnet manufacturing.
