RFeB-based magnet and method for producing RFeB-based magnet

• US 9,818,513 B2
• Filed: 09/30/2014
• Issued: 11/14/2017
• Est. Priority Date: 10/04/2013
• Status: Active Grant

• Current Assignee: Daido Steel Company Limited
• Original Assignee: Daido Steel Company Limited
• Inventors: Takagi, Shinobu
• Primary Examiner(s): Su, Xiaowei
• Application Number:
  US14/502,056
• Publication Number:
  US 20150097643A1
• Time in Patent Office: 1,141 Days
• Field of Search: None
• CPC Class Codes: B23K 20/02 by means of a press ; Diffusion bonding B23K20/001, B23K20/04 take precedence
• CPC Class Codes: B23K 20/026 with diffusion of soldering material
• CPC Class Codes: B23K 20/16 with interposition of special material to facilitate connection of the parts, e.g. material for absorbing or producing gas
• CPC Class Codes: B23K 20/233 without ferrous layer
• CPC Class Codes: B23K 2101/06 Tubes
• CPC Class Codes: B23K 2103/08 Non-ferrous metals or alloys
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: C22C 2202/02 Magnetic
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• 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 1/0576 pressed, e.g. hot working
• CPC Class Codes: H01F 1/0577 sintered
• CPC Class Codes: H01F 41/0293 diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
• CPC Class Codes: H01F 7/02 Permanent magnets [PM]
• CPC Class Codes: H01F 7/021 Construction of PM H01F7/0278 takes precedence; PM compositions H01F1/032

Abstract

Provided is a combined type RFeB-based magnet, including: a first unit magnet; a second unit magnet; and an interface material that bonds the first unit magnet and the second unit magnet, in which the first unit magnet and the second unit magnet are RFeB-based magnets containing a light rare earth element R^L that is at least one element selected from the group consisting of Nd and Pr, Fe, and B, in which the interface material contains at least one compound selected from the group consisting of a carbide, a hydroxide, and an oxide of the light rare earth element R^L, and in which an amount of a heavy rare earth element R^H that is at least one element selected from the group consisting of Dy, Tb and Ho in the second unit magnet is more than that in the first unit magnet.

Claims

1. A combined RFeB-based magnet, comprising:

a first unit magnet;

a second unit magnet; and

an interface material that bonds the first unit magnet and the second unit magnet,

wherein the first unit magnet and the second unit magnet are RFeB-based magnets containing a light rare earth element R^L that is at least one element selected from the group consisting of Nd and Pr, Fe, and B,

wherein the interface material contains at least one compound selected from the group consisting of a carbide, a hydroxide, and an oxide of the light rare earth element R^L, and

wherein an amount of a heavy rare earth element R^H that is at least one element selected from the group consisting of Dy, Tb and Ho in the first unit magnet is 0% by mass to less than 2.0% by mass and an amount of the heavy rare earth element R^H in the second unit magnet is 2.0% by mass to 5% by mass,

wherein a squareness ratio H_k/H_cj that is a ratio of a magnetic field H_k corresponding to 90% of a residual magnetic flux density B_r to a coercive force H_cj in a second quadrant of a magnetization curve is 90% or more, and

wherein a volume ratio of the second unit magnet to the combined RFeB-based magnet is 35% or less.

2. The combined RFeB-based magnet according to claim 1,

wherein bonding surfaces of the first unit magnet and the second unit magnet are planar surfaces.

3. The combined RFeB-based magnet according to claim 1,

wherein the second unit magnet is disposed on a surface side of the combined RFeB-based magnet.

4. The combined RFeB-based magnet according to claim 1,

wherein the combined RFeB-based magnet is plated-shaped and the second unit magnet is disposed at an end portion or a corner portion of the plated-shaped combined RFeB-based magnet.

5. A method for producing the combined RFeB-based magnet of claim 1, comprising:

a grain boundary diffusion treatment step of heating in a state in which bonding surfaces of the first unit magnet and the second unit magnet are brought into contact with each other through paste obtained by mixing a metal powder containing the heavy rare earth element R^H and an organic material.

6. The method for producing the combined RFeB-based magnet according to claim 5,

wherein the bonding surfaces are planar surfaces.