Influence of Demagnetization-Temperature on Magnetic Performance of Recycled Nd-Fe-B Magnets

Stig Högberg, Flemming Buus Bendixen, Nenad Mijatovic, Bogi Bech Jensen, Joachim Holbøll

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Abstract

Recycling rare earth permanent magnets is becoming an important alternative source of supply of raw materials for neodymium-iron-boron (Nd-Fe-B) permanent magnets. This article documents a recycling case-study in which isotropic binder-free magnet powder is extracted and recycled from hermetically-sealed rotors. The extraction process is detailed, and the influence of demagnetization-temperature on the magnetic performance of the recycled product is studied and reported on. Both intrinsic coercivities and the squareness factor of the demagnetization curves are observed to decrease with demagnetizationtemperature. Back-emf measurements of recycled rotors support the relatively low reduction in remanence flux density measured. The results suggest that a protective atmosphere is needed during the heat treatment, by which the rotors are demagnetized, in order to avoid oxidation of the powder.
Original languageEnglish
Title of host publicationProceedings of the 2015 IEEE International Electric Machines and Drives Conference (IEMDC)
PublisherIEEE Press
Publication date2015
Pages1242-1246
ISBN (Print)978-1-4799-7940-0
DOIs
Publication statusPublished - 2015
EventIEEE International Electric Machine and Drives Conference - Coeur d’Alène, Idaho, United States
Duration: 10 May 201513 May 2015
Conference number: 2015
http://iemdc.org/

Conference

ConferenceIEEE International Electric Machine and Drives Conference
Number2015
CountryUnited States
CityCoeur d’Alène, Idaho
Period10/05/201513/05/2015
Internet address

Keywords

  • Electromagnetic analysis
  • Magnetization processes
  • Materials testing
  • Permanent magnet machines
  • Permanent magnet motors
  • Rare earth metals
  • Recycling
  • Rotating machines

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