Increase of energy products of Zn-bonded Sm-Fe-N magnets with low oxygen content

Masashi Matsuura, Yuki Nishijima, Nobuki Tezuka, Satoshi Sugimoto, Tetsuya Shoji, Noritsugu Sakuma

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

To increase the maximum energy product, (BH)max, of Zn-bonded Sm-Fe-N magnets, a process for preparing a Sm-Fe-N powder with a low oxygen content was developed. The Sm-Fe-N powder containing 0.23 wt% oxygen was prepared by ball milling and nitriding, and the powder remanence and coercivity were 140 A·m2kg−1 and 0.72 MA·m−1, respectively. Arc plasma deposition (APD) was used for Zn addition. Fine Zn particles several tens of nanometers in size were deposited on the Sm-Fe-N powder under vacuum conditions, and APD prevented the oxygen content increasing in the Zn-deposited Sm-Fe-N powder. The low-oxygen Sm-Fe-N powder was pressed and sintered by spark plasma sintering (SPS), and 3.3 wt% Zn-bonded and Zn-free Sm-Fe-N magnets were prepared. For both Zn-bonded and Zn-free Sm-Fe-N magnets, the density increased with increasing sintering pressure, and the relative density of the Zn-bonded Sm-Fe-N magnet was 89% and that of the Zn-free Sm-Fe-N magnet was 85% after SPS. The coercivities of the Zn-bonded and Zn-free Sm-Fe-N magnets were both high at 1.1 and 0.8 MA·m−1, respectively. (BH)max of these magnets increased with increasing relative density, and the highest (BH)max value of the Zn-bonded Sm-Fe-N magnets was 153 kJ·m−3 and that of the Zn-free Sm-Fe-N magnet was 179 kJ·m−3.

Original languageEnglish
Pages (from-to)64-68
Number of pages5
JournalJournal of Magnetism and Magnetic Materials
Volume467
DOIs
Publication statusPublished - 2018 Dec 1

Keywords

  • Arc plasma deposition
  • Binder less
  • Maximum energy products
  • Oxygen content
  • Sm-Fe-N magnets
  • Spark plasma sintering
  • Zn binder

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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