分子鎖配向を利用したラジアル異方性希土類ボンド磁石

Abstract

Magnetic properties of radially-anisotropic ring-shaped magnets were deteriorated when their outer-diameter is decreased down. Therefore, anisotropic Nd2Fe14B bonded-magnets have not been mainly applied to small motors up to now. In order to overcome the above difficulty, we developed a new technique using self-organization of binder which enabled the alignment of molecular-chain. By using this technique, we controlled the flexibility of Nd2Fe14B /Sm2Fe17N3 rigid sheet-magnets (approximately 1 mm in thickness), transformed them into various shapes, and succeeded in preparing radially-anisotropic ring- or arc-shaped magnets. Optimizations of the solidification process of the binder under a transverse alignment-field and the transformation process into various specific shapes realized radially-anisotropic magnets with superior properties such as values of (BH)max and also magnetic stabilities. Their value of (BH)max exceeded 160 kJ/m3, even if their outer diameter is less than 25 mm.