Complex Characteristics of Sintered Nd-Fe-B Magnets in Terms of Hydrogen Based Recycling

• Authors: M. Szymański , B. Michalski , M. Leonowicz , Z. Miazga
• Languages of publication: EN

Abstracts

EN

Sintered Nd-Fe-B magnets, dismantled by the P.P.H.U. Polblume company from scrap hard disc drives and medical device, were thermally demagnetized and analyzed in terms of their chemical composition, structure and magnetic properties. Magnets from hard disc drives drives had a magnetic structure of two opposite poles in a plane of a magnet and were covered with a nickel coating (around 50 μ m in thick), which however was often discontinuous and deeply scratched. The majority of the magnets were partially destroyed (broken or corroded). The magnet from hard disc drives were basically made of iron (65±1 wt%) and neodymium (30±2 wt%) however, they also included alloying elements such as Co (1-2.5 wt%), Dy (0-1 wt%) or Pr (0-5 wt%). The magnets from medical device consisted only of iron (65±1 wt%) and neodymium (34±1 wt%). Magnets of both kinds were textured thus their XRD patterns were amended. Diffraction patterns, typical for the Nd₂Fe₁₄B (φ) phase, were achieved after mechanical crushing of the bulk magnets. A regular X-ray diffraction pattern was achieved after mechanical crushing of the magnets. The microstructure of both types of the magnets, observed by scanning electron microscopy, consisted of grey grains of a Nd₂Fe₁₄B (φ) phase and a Nd-rich grain boundary phase. The magnets from hard disc drives exhibited excellent magnetic properties and anisotropy: maximum energy product above 300 kJ/m³, remanence around 1.4 T and coercivity around 1000 kA/m, slightly varying between each magnet. Magnetic properties of medical magnet were only a little worse: maximum energy product above 200 kJ/m³, remanence around 1.1 T and coercivity around 900 kA/m. Hydrogen disproportionation phase diagrams (temperature vs. pressure) were constructed for both kinds of the magnets, revealing possible conditions for the hydrogenation, disproportionation, desorption and recombination reaction.

Keywords

EN

75.50.Ww

Discipline

• 75.50.Ww: Permanent magnets(for magnets, see 07.55.Db in instruments)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2017
• Volume: 131
• Issue: 5
• Pages: 1270-1273

Dates

published

2017-05

Contributors

author

M. Szymański

• Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02-507 Warsaw, Poland

author

B. Michalski

• Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02-507 Warsaw, Poland

author

M. Leonowicz

• Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02-507 Warsaw, Poland

author

Z. Miazga

• P.P.H.U. Polblume Zbigniew Miazga, 11. Listopada 35, 05-500 Piaseczno, Poland

References

• [1] Critical Raw Materials, European Commission, Growth, (access on February 22, 2017) http://ec.europa.eu/growth/sectors/raw-materials/specific-interest/critical/index_en.htm
• [2] S. Massari, M. Ruberti, Resour. Policy 38, 36 (2013), doi: 10.1016/j.resourpol.2012.07.001
• [3] A. Rubtsov, HDD from Inside: Hard Drive Main Parts, HDDScan Utility. (access on February 22, 2017) http://hddscan.com/doc/HDD_fromınside.html
• [4] A. Walton, Yi Han, N.A. Rowson, J.D. Speight, V.S.J. Mann, R.S. Sheridan, A. Bradshaw, I.R. Harris, A.J. Williams, J. Clean. Prod. 104, 236 (2015), doi: 10.1016/j.jclepro.2015.05.033
• [5] N. Katagiri, K. Ijima, K. Halada, NIMS NOW Int. 7, 9 (2009)
• [6] A. Zhang, in: Conf. Proc. 23rd Int. Workshop on Rare Earth and Future Permanent Magnets and Their Applications REPM-2014, Annapolis (USA), 2014, Ed. G.C. Hadjipanayis, p. 1
• [7] D.N. Brown, L.Y. Keat, Z. Wei, H. Feng, J.W. Herchenroeder, in Ref. [6], p. 45
• [8] K. Binnemans, P.T. Jones, B. Blanpain, T. Van Gerven, Y. Yang, A. Walton, M. Buchert, J. Clean. Prod. 51, 1 (2013), doi: 10.1016/j.jclepro.2012.12.037
• [9] R.S. Sheridan, A.J. Williams, I.R. Harris, A. Walton, J. Magn. Magn. Mater. 350, 114 (2014), doi: 10.1016/j.jmmm.2013.09.042
• [10] M. Szymański, B. Michalski, M. Leonowicz, Z. Miazga, Key Eng. Mater. 682, 308 (2016), doi: 10.4028/www.scientific.net/KEM.682.308
• [11] Additives in Neodymium Iron Boron magnets, EU FP7 Marie-Curie Initial Training Network, (access on February 22, 2017) http://erean.eu/wordpress/additives-in-ndfeb-magnets
• [12] A. Walton, Recycling of rare earth earth materials, ERECON - European Rare Earth Competency Network, (access on February 22, 2017) http://ec.europa.eu/growth/tools-databases/eip-raw-materials/sites/rawmaterials/files/3%20-%20Walton%20EIP%20talk%20for%20ERECON.pdf
• [13] K. Baba, Y. Hiroshige, T. Nemoto, Hitachi Rev. 62, 452 (2013)
• [14] Hitachi Develops Recycling Technologies for Rare Earth Metals, Hitachi Global, (access on February 22, 2017) http://www.hitachi.com/New/cnews/101206.html
• [15] R.S. Sheridan, Ph.D. Thesis, School of Metallurgy and Materials, College of Engineering and Physical Sciences, University of Birmingham, 2013 http://etheses.bham.ac.uk/4929/1/Sheridan14PhD.pdf

Identifiers

DOI

10.12693/APhysPolA.131.1270