PRODUCTION METHOD OF RARE EARTH MAGNET AND PRODUCTION APPARATUS USED THEREFOR

• US 20190311826A1
• Filed: 03/04/2019
• Published: 10/10/2019
• Est. Priority Date: 04/09/2018
• Status: Active Application

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: SAKUMA, Noritsugu, HAGA, Kazuaki
• Application Number:
  US16/291,239
• Publication Number:
  US 20190311826A1
• Time in Patent Office: Days
• CPC Class Codes: B22F 1/06 Metallic powder characterised by the shape of the particles nanosized particles B22F1/054
• CPC Class Codes: B22F 1/105 containing inorganic lubricating or binding agents, e.g. metal salts
• CPC Class Codes: B22F 2202/05 Use of magnetic field
• CPC Class Codes: B22F 2301/30 Low melting point metals, i.e. Zn, Pb, Sn, Cd, In, Ga
• CPC Class Codes: B22F 2301/355 Rare Earth - Fe intermetallic alloys
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/003 Apparatus, e.g. furnaces in general F27B
• CPC Class Codes: B22F 3/03 Press-moulding apparatus therefor
• CPC Class Codes: B22F 3/16 in successive or repeated steps
• CPC Class Codes: C22C 1/05 Mixtures of metal powder with non-metallic powder C22C1/08 takes precedence
• CPC Class Codes: C22C 2202/02 Magnetic
• CPC Class Codes: C22C 33/0228 comprising other non-metallic compounds or more than 5% of graphite
• 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 1/0557 sintered
• CPC Class Codes: H01F 1/059 and Va elements, e.g. Sm2Fe17N2
• CPC Class Codes: H01F 1/08 pressed, sintered, or bound together
• CPC Class Codes: H01F 1/086 sintered
• CPC Class Codes: H01F 41/0266 Moulding; Pressing H01F41/0273 takes precedence; hard magnetic particles H01F1/06, H01F1/11
• CPC Class Codes: H01F 41/0273 : Imparting anisotropy methods and devices for magnetising permanent magnets H01F13/003
• CPC Class Codes: H01F 41/0293 : diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets

Abstract

To provide a production method capable of enhancing the magnetic properties, particularly, the coercive force, of a Sm—Fe—N-based rare earth magnet and a production apparatus used therefor.

A method for producing a rare earth magnet, comprising mixing a magnetic raw material powder containing Sm, Fe and N with a modifier powder containing metallic Zn to obtain a mixed powder, filling the mixed powder into a molding die to obtain a filled product, melting at least a part of the modifier powder in the filled product while applying a pressure of 20 MPa or less to the filled product or without applying a pressure to obtain an intermediate molded product, and subjecting the intermediate molded product to liquid phase sintering at a pressure of 20 MPa or more to obtain a sintered body; and a production apparatus used therefor.

Claims

1. A method for producing a rare earth magnet, comprising:

mixing a magnetic raw material powder containing Sm, Fe and N with a modifier powder containing metallic Zn to obtain a mixed powder,

filling the mixed powder into a molding die to obtain a filled product,

melting at least a part of the modifier powder in the filled product while applying a pressure of 20 MPa or less to the filled product or without applying a pressure to obtain an intermediate molded product, and

subjecting the intermediate molded product to liquid phase sintering at a pressure of 20 MPa or more to obtain a sintered body.

2. The method according to claim 1, wherein the magnetic raw material powder contains a magnetic phase represented by (Sm_(1-i)R_i)₂(Fe_(1-j)Co_j)₁₇N_h (wherein R is one or more members selected from Y, Zr and rare earth elements other than Sm, i is from 0 to 0.50, j is from 0 to 0.52, and h is from 1.5 to 4.5).

3. The method according to claim 1, wherein the oxygen content of the magnetic raw material powder is 1.05 mass % or less.

4. The method according to claim 1, wherein the average particle diameter of the modifier powder is 20 μ

m or less.

5. The method according to claim 1, wherein the mixed powder is filled into the molding die and compacted in a magnetic field to obtain a filled product having an oriented magnetic field.

6. An apparatus for producing a rare earth magnet, which is used for the method according to claim 1, the rare earth magnet production apparatus comprising:

a molding die into which the mixed powder is filled,

a heater for heating the molding die, and

a pressure member for applying a pressure to the filled product and the intermediate molded product,

wherein

the molding die comprises a main die having a through hole and punch dies inserted at both ends of the through hole to be slidable in the axial direction of the through hole,

the heater is disposed on an outer periphery of the main die, and

the pressure member is connected to at least either one of the punch dies.

7. The apparatus according to claim 6, wherein the main die and the punch die are at least partially made of tungsten carbide.

8. The apparatus according to claim 6, wherein a temperature sensor is disposed in the main die.

9. The apparatus according to claim 6, wherein the heater includes an induction heating coil.

10. The apparatus according to claim 6, wherein the pressure member includes at least either one of a fluid cylinder and an electric cylinder.

11. The apparatus according to claim 6, further comprising an electromagnetic coil outside the molding die.