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US 7,608,153 B2Granted
Rare earth magnet and method therefor
AssigneeNissan Motor Co., Ltd.
InventorsTetsurou Tayu, Hideaki Ono, Yoshio Kawashita, Makoto Kano, Munekatsu Shimada
Life of this patent
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Abstract
A rare earth magnet includes rare earth magnet particles; and amorphous and/or crystalline terbium oxide present at the boundary of the rare earth magnet particles and represented by the formula: TbOn, wherein 1.5<n≦2. The rare earth magnet prevents decrease eddy current effectively.
Claims14
A rare earth magnet, comprising:
- rare earth magnet particles;
- and
- amorphous and/or crystalline terbium oxide present at a boundary of the rare earth magnet particles and represented by the formula:
- TbOn, wherein 1.5 <n≦2;
- wherein said rare earth magnet particles are connected by said terbium oxide, and wherein individual rare earth magnet particles comprise a cluster of fine crystal grains;
- wherein the terbium oxide is contained in an amount of 1 to 10 wt % based on a weight of the rare earth magnet.
3 more elements
A method for producing a rare earth magnet, comprising:
- a coating process of covering whole of or a part of a surface of rare earth magnet powder with terbium alkoxide by applying a liquid including the terbium alkoxide to the surface of the rare earth magnet powder under a dry atmosphere;
- a hydrolysis process of hydrolyzing the terbium alkoxide at the surface of the rare earth magnet powder to obtain a first intermediate magnetic powder;
- a heating process of heat-treating the first intermediate magnetic powder under a vacuum atmosphere or an inert gas atmosphere to obtain a second intermediate magnetic powder;
- a filling process of filling the second intermediate magnetic powder into a mold;
- and
- a molding process of molding the second intermediate magnetic powder filled in the mold to produce a rare earth magnet comprising rare earth magnet particles and amorphous and/or crystalline terbium oxide present at a boundary of the rare earth magnet particles represented by the formula:
- TbOn, wherein 1.5 <n≦2;
- wherein said rare earth magnet particles are connected by said terbium oxide, and at least one rare earth magnetic particle comprises a cluster of fine crystal grains;
- wherein the terbium oxide is contained in an amount of 1 to 10 wt % based on a weight of the rare earth magnet.
6 more elements
Dependencies are inferred from the claim text.