METHOD OF MANUFACTURING MAGNET, AND MAGNET

• US 20130222093A1
• Filed: 02/20/2013
• Published: 08/29/2013
• Est. Priority Date: 02/27/2012
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: SUGIYAMA, Kazuhisa, BABA, Toshiyuki
• Granted Patent: US 9,601,246 B2
• Time in Patent Office: Days
• US Class Current: 335/302
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/005 containing rare earths, i.e. Sc, Y, Lanthanides
• CPC Class Codes: H01F 1/01 of inorganic materials H01F1/44 takes precedence
• CPC Class Codes: H01F 1/0596 of rhombic or rhombohedral Th2Zn17 structure or hexagonal Th2Ni17 structure
• CPC Class Codes: H01F 1/065 obtained by a reduction
• CPC Class Codes: H01F 1/08 pressed, sintered, or bound together
• CPC Class Codes: H01F 7/02 Permanent magnets [PM]

Abstract

A hard magnetic material formed of material powders made of a R—Fe—N compound containing a light rare earth element as R, or material powders made of a Fe—N compound is used as material powders. There is formed a compact in which a density of the hard magnetic material powders differs between an outer face side portion and an inside portion of the compact such that a rate of progress of powder bonding due to microwave heating is higher in the inside portion of the compact than in the outer face side portion of the compact when an outer face of the compact is irradiated with microwaves. Then, the outer face of the compact is irradiated with the microwaves to cause the microwave heating, thereby bonding the hard magnetic material powders by oxide films which are formed on the hard magnetic material powders.

Claims

1. A method of manufacturing a magnet from a hard magnetic material formed of material powders made of a R—

Fe—

N compound containing a light rare earth element as R, or material powders made of a Fe—

N compound, the method characterized by comprising;

a forming step of forming a compact in which a density of the hard magnetic material powders differs between an outer face side portion and an inside portion of the compact such that a rate of progress of powder bonding due to microwave heating is higher in the inside portion of the compact than in the outer face side portion of the compact when an outer face of the compact is irradiated with microwaves; and

a microwave heating step of irradiating the outer face of the compact with the microwaves to cause the microwave heating, thereby bonding the hard magnetic material powders by oxide films that are formed on the hard magnetic material powders.

2. The method of manufacturing a magnet according to claim 1, wherein, in the forming step, multiple types of the hard magnetic material powders having different particle sizes are used to form the compact such that the hard magnetic material powders are arranged in the compact such that that the density of the hard magnetic material powders is higher in the inside portion of the compact than in the outer face side portion of the compact.

3. The method of manufacturing a magnet according to claim 2, wherein, in the forming step, the compact is formed by using a centrifuge such that the hard magnetic material powders having a smaller particle size are arranged in the inside portion of the compact and the hard magnetic material powders having a larger particle size are arranged in the outer face side portion of the compact.

4. A method of manufacturing a magnet from a hard magnetic material foamed of material powders made of a R—

Fe—

N compound containing a light rare earth element as R, or material powders made of a Fe—

N compound, and an insulating material formed of insulating material powders, the method characterized by comprising;

a forming step of forming a compact from the hard magnetic material and the insulating material that is different in relative permittivity from the hard magnetic material, such that one of the hard magnetic material and the insulating material, which is higher in relative permittivity than the other one of the hard magnetic material and the insulating material, is arranged in an inside portion of the compact and the other one of the hard magnetic material and the insulating material is arranged in an outer surface portion of the compact; and

a microwave heating step of irradiating an outer face of the compact with the microwaves to cause microwave heating, thereby bonding the material powders by oxide films that are formed on the material powders.

5. The method of manufacturing a magnet according to claim 4, wherein, in the forming step, a centrifuge is used to form the compact such that one of the hard magnetic material and the insulating material, which is higher in relative permittivity and smaller in mass per one particle than the other one of the hard magnetic material and the insulating material, is arranged in the inside portion of the compact and the other one of the hard magnetic material and the insulating material is arranged in the outer surface portion of the compact.

6. The method of manufacturing a magnet according to claim 4, wherein the insulating material is a soft magnetic material.

7. The method of manufacturing a magnet according to claim 5, wherein the insulating material is a soft magnetic material.

8. A magnet formed from a hard magnetic material formed of material powders made of a R—

Fe—

N compound containing a light rare earth element as R, or material powders made of a Fe—

N compound, characterized in that the magnet is manufactured by forming a compact in which a density of the hard magnetic material powders differs between an outer face side portion and an inside portion of the compact such that a rate of progress of powder bonding due to microwave heating is higher in the inside portion of the compact than in the outer face side portion of the compact when an outer face of the compact is irradiated with microwaves, and irradiating the outer face of the compact with the microwaves to cause the microwave heating, thereby bonding the hard magnetic material powders by oxide films that are formed on the hard magnetic material powders.