Method for producing magnetically anisotropic permanent magnet

• US 5,562,782 A
• Filed: 05/05/1995
• Issued: 10/08/1996
• Est. Priority Date: 10/06/1993
• Status: Expired due to Fees

• Current Assignee: Kawasaki Teitoku Co., Ltd., Komeya Incorporated, Sanei Kasei Co., Limited
• Original Assignee: Kawasaki Teitoku Co., Ltd., Komeya Incorporated, Sanei Kasei Co., Limited
• Inventors: Takahashi, Yasunori
• Primary Examiner(s): SHEEHAN, JOHN P
• Application Number:
  US08/435,134
• Time in Patent Office: 522 Days
• Field of Search: 148/103, 148/104, 419/12, 419/35, 252/62.54
• US Class Current: 148/104
• CPC Class Codes: B22F 1/142 Thermal or thermo-mechanical treatment
• CPC Class Codes: B22F 1/16 Metallic particles coated with a non-metal coated with lubricating or binding agents or with organic material B22F1/10
• CPC Class Codes: H01F 1/0573 obtained by reduction or by hydrogen decrepitation or embrittlement
• CPC Class Codes: H01F 1/0577 sintered
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

The present invention aims at providing a powdery raw material composition for a permanent magnet superior in the magnetic properties and easy in preparation, a magnetically anisotropic permanent magnet, and a method for producing the magnet by use of the powdery raw material composition. A powdery raw material composition for a permanent magnet according to the present invention is one prepared by subjecting a mixture composed of 13-18 weight % of a neodymium powder, 4-10 weight % of a boron powder and the rest of an acicular iron powder coated with aluminum phosphate to a temperature above 600° C. in an atmosphere initially of a hydrogen-containing reducing gas followed later by an inert gas, and a magnetically anisotropic permanent magnet is prepared by compression molding a mixture obtained from the powdery composition and a binder under heating in the presence of a magnetic field.

Claims

1. A method for producing magnetically anisotropic permanent magnets, the method comprising the steps of:

producing a powdery composition by subjecting a mixture comprising 13-18 weight % of a neodymium powder, 4-10 weight % of a boron powder and the rest of an acicular iron powder coated with aluminum phosphate to a temperature above 600°

C. in an atmosphere initially of a hydrogen-containing reducing gas followed by subjecting the powdery composition to a temperature above 600°

C. in an inert gas;

mixing the powdery composition with a binder; and

compression molding the binder mixture under heating in the presence of a magnetic field to thereby form the permanent magnet.

2. The method according to claim 1, wherein the weight ratio between the acicular iron powder and aluminum phosphate is 8:

1-20;

1.

3. The method according to claim 1, wherein the powdery composition is heated to a temperature of 800°

-1000°

C. in an atmosphere initially of a hydrogen-containing reducing gas.

4. The method according to claim 1, wherein the binder comprises an epoxy resin.