Permanent magnet and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-9275778-B2
Application number	US-93318009-A
Country	US
Kind code	B2
Filing date	Mar 17, 2009
Priority date	Mar 18, 2008
Publication date	Mar 1, 2016
Grant date	Mar 1, 2016

Abstract

The present invention relates to a permanent magnet obtained by wet-mixing a Dy compound or a Tb compound with a magnet raw material to coat a surface of the magnet raw material with the Dy compound or the Tb compound, and sintering a green sheet obtained by mixing the resulting magnet raw material with a resin binder and molding the resulting mixture. Since the present invention has the above-mentioned constitution, it becomes possible to sufficiently improve coercive force by Dy or Tb while decreasing the amount of Dy or Tb used. Further, it can be prevented that Dy or Tb is solid-solutionized in magnet particles to decrease residual magnetization.

First claim

The invention claimed is:

1. A method for manufacturing a permanent magnet, said method comprising:
a step of wet-mixing a Dy compound precursor or a Tb compound precursor with a magnet raw material in the form of a powder in a solvent;
a step of adding a resin binder to the magnet raw material coated with the Dy compound precursor or the Tb compound precursor;
a step of producing a slurry by kneading the magnet raw material and the resin binder;
a step of molding the slurry into a sheet form to prepare a green sheet; and
a step of sintering the green sheet,
wherein the permanent magnet is a Nd—Fe—B-based permanent magnet comprising 27 to 30 weight % of Nd, 60 to 70 wt % of Fe, and 1 to 2 weight % of B, and the Dy compound or the Tb compound is formed at the grain boundaries,
wherein the Dy compound precursor or Tb compound precursor is soluble in the solvent, and
wherein the Dy compound precursor or Tb compound precursor is an organic acid salt, an organic complex, or an organic metal compound.

2. The method for manufacturing a permanent magnet according to claim 1 , wherein the Dy compound or the Tb compound is contained in an amount of from 0.01 to 8 wt %.

Assignees

• Ozeki Izumi
• Kume Katsuya
• Nakayama Junichi
• Fukuda Yuuki
• Hoshino Toshinobu
• Horio Tomokazu
• Nitto Denko Corp

Inventors

• Ozeki Izumi
• Kume Katsuya
• Nakayama Junichi
• Fukuda Yuuki
• Hoshino Toshinobu
• Horio Tomokazu

Classifications

• H01F1/0552

  with a protective layer · CPC title

• H01F41/16

  the magnetic material being applied in the form of particles, e.g. by serigraphy {, to form thick magnetic films or precursors therefor} (H01F41/18 {-H01F41/24} take precedence) · CPC title

• H01F1/0577

  sintered · CPC title

• H01F1/0557

  sintered · CPC title

• H01F1/0572 Primary

  with a protective layer · CPC title