Perryville, MD, United States
Perryville, MD, United States

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Sepehri-Amin H.,Japan National Institute of Materials Science | Ohkubo T.,Japan National Institute of Materials Science | Zaktonik M.,Urban Mining Technology Co. | Prosperi D.,Urban Mining Technology Co. | And 3 more authors.
Journal of Alloys and Compounds | Year: 2017

Full-density recycled Nd-Fe-B sintered magnets were produced from collected waste Nd-Fe-B magnets with the coercivity, μ0Hc, of 1.30 T and remanence, μ0Mr, of 1.37 T. A small fraction of Nd6Dy21Co19Cu2.5Fe powder (Grain Boundary Modified (GBM™) powder) was blended to the powders obtained from the Nd-Fe-B waste magnets. The addition of 5.0 wt% GBM™ powder resulted in μ0Hc = 2.36 T with μ0Mr = 1.29 T in recycled magnets. The temperature coefficient of intrinsic coercivity, β, in the recycled magnet was measured to be −0.47%/oC. Microstructure studies showed that the addition of the GBM™ powder increases the volume fraction of a metallic Nd-rich phase in the recycled magnets. 3D tomography revealed a good interconnection of Nd-rich phases through the grain boundaries of the recycled magnet. Microstructure studies suggested that obtained high coercivity in the recycled magnet with 5.0 wt% addition of GBM™ is due to the formation of distinct grain boundary phase combined with the formation of Dy-rich shell in the Nd2Fe14B grains with ∼0.8 at. % Dy. © 2016 Elsevier B.V.


Zakotnik M.,Urban Mining Technology Co. | Tudor C.O.,Urban Mining Technology Co.
Waste Management | Year: 2015

NdFeB-type magnets dominate the market for high performance magnetic materials, yet production of 'virgin' magnets via mining is environmentally, financially and energetically costly. Hence, interest is growing in 'magnet to magnet' recycling schemes that offer the potential for cheaper, more environmentally-friendly solutions to the world's growing appetite for rare-earth based magnetic materials. Unfortunately, previously described recycling processes only partially capitalise on this potential, because the methods described to date are limited to 'laboratory scale' or operate only under ideal conditions and result in products that fail to recapture the coercivity of the starting, scrap materials.Herein, we report a commercial scale process (120. kg batches) that completely recovers the properties of the starting scrap magnets. Indeed, 'grain boundary modification', via careful addition of a proprietary mix of blended elements, produces magnets with 'designer properties' that can exceed those of the starting materials and can be closely tailored to meet a wide variety of end-user applications, including high-coercivity (>2000. kA/m), sintered magnets suitable for motor applications. © 2015 Elsevier Ltd.


NdFeB-type magnets dominate the market for high performance magnetic materials, yet production of virgin magnets via mining is environmentally, financially and energetically costly. Hence, interest is growing in magnet to magnet recycling schemes that offer the potential for cheaper, more environmentally-friendly solutions to the worlds growing appetite for rare-earth based magnetic materials. Unfortunately, previously described recycling processes only partially capitalise on this potential, because the methods described to date are limited to laboratory scale or operate only under ideal conditions and result in products that fail to recapture the coercivity of the starting, scrap materials. Herein, we report a commercial scale process (120 kg batches) that completely recovers the properties of the starting scrap magnets. Indeed, grain boundary modification, via careful addition of a proprietary mix of blended elements, produces magnets with designer properties that can exceed those of the starting materials and can be closely tailored to meet a wide variety of end-user applications, including high-coercivity (>2000 kA/m), sintered magnets suitable for motor applications.

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