Details

Autor(en) / Beteiligte

• Lu, Qingmei
• Shao, Yanzhao
• Yin, Yantao
• Chen, Hao
• Xu, Haibo
• Liu, Weiqiang
• Liu, Min
• Zhong, Changchuan
• Yu, Xi
• Chen, Jingwu
• Liu, Youhao
• Yi, XiaoFei
• Yue, Ming

Titel

Mass production of regenerated sintered NdFeB magnets with improved magnetic properties compared to original magnets

Ist Teil von

• Sustainable Materials and Technologies, 2023-07, Vol.36, p.e00615, Article e00615

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2023

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Machined sintered NdFeB (S-NdFeB) wastes typically contain about 30 wt% rare earth (RE) elements which are beneficial as supplemental RE resources. In this work, we studied one type of oily and adhesive-containing scraps, and developed a high-value recycling technique based on surface treatments-RE manipulation-grain boundary diffusion, specifically to directly generate multi-grade, high-performance S-NdFeB magnets. We obtained clean-surface scraps with RE mass loss of less than 4% and oxygen content below 2000 ppm using a custom-made solvent. By increasing content of the RE-rich alloy (Nd4Fe14B), we quickly improved the performance of the regenerated magnets. When the addition was 15 wt%, the magnetic properties exceeded that of the original magnet, with a remanence of 12.5 kG, coercivity of 17.79 kOe, and maximum energy product of 37.95 MGOe. Furthermore, the magnets were subjected to 1 wt% TbHx-diffusion treatment, which further optimized the performance, and the coercivity exhibited a 50% improvement to 26.71 kOe, which greatly expanded the application in motors and generators. Microstructure analysis indicated that the improved magnetic performance of the regenerated magnets was mainly derived from the restoration of the RE-rich phase, and the Nd2Fe14B-(Nd/Tb)2Fe14B core-shell structure, which had a high anisotropic field. Based on the above recycling methods, we successfully established an energy conservation and efficient recycling line for S-NdFeB wastes at a scale of five hundred tons/year. [Display omitted] •Develop a high-efficiency technique to achieve full regeneration of S-NdFeB scraps.•Regenerated NdFeB magnets showed multi-grade and higher magnetic properties.•Large-scale regeneration of S-NdFeB wastes was successfully achieved.