Estimation of Demagnetization Curve of Magnet with Nonuniform Coercivity

• Tokushige Takayuki

  Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University

• Umabuchi Masafumi

  Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University

• Miyagi Daisuke

  Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University

• Takahashi Norio

  Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University

• Ito Masaru

  Magnetic Materials Research Center, Shin-Etsu Chemical Co., Ltd.

• Hirota Koichi

  Magnetic Materials Research Center, Shin-Etsu Chemical Co., Ltd.

Bibliographic Information

Other Title

• 保磁力分布磁石の減磁曲線の推定法
• ホジリョク ブンプ ジシャク ノ ゲンジキョクセン ノ スイテイホウ

Abstract

Neodymium-iron-boron (Nd-Fe-B) magnets exhibit exceedingly high maximum energy products and remanences. Their coercivities, however, decrease rapidly with increasing the temperature, and the magnets are easily demagnetized at elevated temperatures. To reduce the effects of temperature, the coercivity at the room temperature is enhanced by the addition of the dysprosium (Dy), which causes a reduction in remanence. The Grain Boundary Diffusion process is a technology to enhance coercivities while suppressing a large reduction in remanences. Dy that is effective for the coercivity enhancement is supplied from the magnet surface and diffused into the magnets through the grain boundary phase, and then put at the grain surface. When the Grain Boundary Diffusion process is applied to relatively large magnets, the partial coercivities near the magnet surface, where higher coercivities are generally required, can be enhanced effectively. In other words, the magnets exhibit nonuniform coercivity. We have conceived a simple and effective method for estimating the demagnetization curves of such nonuniform coercivity magnets. In this paper, the validity of the estimation method was examined.

Journal

• IEEJ Transactions on Fundamentals and Materials

  IEEJ Transactions on Fundamentals and Materials 132 (1), 101-107, 2012

  The Institute of Electrical Engineers of Japan

Keywords

• coercivity distribution magnet
• estimation of demagnetization curve

Details

• CRID: 1390001204599226496
• NII Article ID: 10030523769
• NII Book ID: AN10136312
• DOI: 10.1541/ieejfms.132.101
• BIBCODE: 2012IJTFM.132..101T
• ISSN: 13475533
• ISSN: 03854205
• NDL BIB ID: 023416372
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I023416372
• Web Site: https://www.jstage.jst.go.jp/article/ieejfms/132/1/132_1_101/_pdf
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed