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High performance Sm-Fe-N Zn-bonded magnets prepared using powders with low oxygencontent

The 25th International Workshop on Rare-Earth and Future Permanent Magnetsand their Applications (REPM2018),2018.8.26-30, Beijing,China

2018年8月27日(月)

Satoshi Sugimoto, Yuki Nishijima, Ryo Matsunami, Masashi Matsuura, Nobuki Tezuka (TohokuUniverisity) Noritsugu Sakuma, Tetsuya Shoji (Toyota Motor Corp.)

Abstract

Sm-Fe-N Zn-bonded magnet has been expected as a high performance magnet with high heat resistance becauseof good magnetic properties of Sm2Fe17N3 compound. However, reduction of Zn and oxygen (O) content, andimprovement of Zn dispersibility are needed for the enhancement of maximum energy products (BH)max. In ourprevious study [1], we used hydrogen plasma-metal reaction (HPMR) for preparation of fine Zn particles with low Ocontent and succeeded to improve the coercivity (HcJ) of Sm-Fe-N Zn-bonded magnets. The primary andsecondary average particle sizes of Zn powders prepared by HPMR were 0.23 and 0.93 μm, respectively, and the Ocontent was 0.068 wt%. The HcJ of the 15 wt% Zn Sm-Fe-N Zn-bonded magnet was 2.66 MAm-1. This high HcJwas strongly depended on the O content. The Zn-bonded magnet also showed high HcJ of 1.10 MAm-1 at 200 ℃ ,and the temperature coefficient of coercivity was -0.32 %/℃. In this study, we applied arc plasma deposition (APD)for the deposition of fine and well-dispersed Zn particles on the surface of Sm-Fe-N powders, in which O contentwas decreased. Then, we prepared Sm-Fe-N Zn-bonded magnets using the powders and investigated theirmagnetic properties. From the microstructure observations using SEM taken from Zn-deposited Sm-Fe-N powders,Zn nanoparticles was observed on the surface of Sm-Fe-N powders. The Sm-Fe-N Zn-bonded magnet using thispowders exhibited higher magnetic properties than those prepared by conventional method. As the Zn distributionwas improved in the powders, the Zn content in Zn-bonded Sm-Fe-N magnets could be decreased, whichsuppressed the decrease in magnetization value. In addition, the samples showed O content of 0.226 wt.%, whichwas one-third as much as the O content in commercial Sm-Fe-N powder. Therefore, it can be said that decreasingZn particle size and O content of the starting Sm-Fe-N and Zn powders improve magnetic properties of Sm-Fe-NZn-bonded magnets.

その他特記事項

This work was partially supported by the Future Pioneering Program“Development of magnetic material technology for high-efficiency motors” commissioned by the NEDO, Japan,and by the Elements Strategy Initiative Center for Magnetic Materials (ESICMM) under the outsourcing project ofMEXT, Japan.


研究活動

文部科学省

文部科学省
元素戦略プロジェクト(活動紹介)
NIMS磁石パートナーシップ

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