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

Journal of Magnetism and Magnetic Materials Vol.467, Pages 64-68

2018年7月21日(土)

Masashi Matsuura, Yuki Nishijima, Nobuki Tezuka, Satoshi Sugimoto (Tohoku University) Tetsuya Shoji, Noritsugu Sakuma (Toyota motor Corporation) ( https://doi.org/10.1016/j.jmmm.2018.07.064 )

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.




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文部科学省
元素戦略プロジェクト(活動紹介)
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元素戦略拠点

触媒・電池元素戦略拠点
触媒・電池元素戦略研究拠点 (京都大学)
東工大元素戦略拠点
東工大元素戦略拠点 (東京工業大学)
構造材料元素戦略研究拠点
構造材料元素戦略研究拠点 (京都大学)
高効率モーター用磁性材料技術研究組合
高効率モーター用 磁性材料技術研究組合