Method for manufacturing R-T-B based sintered magnet

Patent metadata

Field	Value
Publication number	US-10217562-B2
Application number	US-201615528781-A
Country	US
Kind code	B2
Filing date	Feb 23, 2016
Priority date	Feb 27, 2015
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

A method for producing a sintered R-T-B based magnet of this disclosure includes the steps of preparing a plurality of sintered R-T-B based magnet bodies (R is at least one of rare earth elements and necessarily contains Nd and/or Pr; and T is at least one of transition metals and necessarily contains Fe); preparing a plurality of alloy powder particles having a size of 90 μm or less and containing a heavy rare earth element RH (the heavy rare earth RH is Tb and/or Dy) at a content of 20 mass % or greater and 80 mass % or less; loading the plurality of sintered R-T-B based magnet bodies and the plurality of alloy powder particles of a ratio of 2% by weight or greater and 15% by weight or less with respect to the plurality of sintered R-T-B based magnet bodies into a process chamber; and heating, while rotating and/or swinging, the process chamber to move the sintered R-T-B based magnet bodies and the alloy powder particles continuously or intermittently to perform an RH supply and diffusion process.

First claim

The invention claimed is:

1. A method for producing a sintered R-T-B based magnet, comprising the steps of:
providing a plurality of sintered R-T-B based magnet bodies (R is at least one of rare earth elements and necessarily contains Nd and/or Pr; and T is at least one of transition metals and necessarily contains Fe);
providing a plurality of alloy powder particles having a size of 90 μm or less and containing a heavy rare earth element RH (the heavy rare earth RH is Tb and/or Dy) at a content of 20 mass % or greater and 80 mass % or less;
loading the plurality of sintered R-T-B based magnet bodies and the plurality of alloy powder particles of a ratio of 2% by weight or greater and 15% by weight or less with respect to the plurality of sintered R-T-B based magnet bodies into a process chamber; and
heating, while rotating and/or swinging, the process chamber to move the sintered R-T-B based magnet bodies and the alloy powder particles continuously or intermittently to perform an RH supply and diffusion process.

2. The method for producing a sintered R-T-B based magnet according to claim 1 , wherein the plurality of sintered R-T-B based magnet bodies necessarily contain Nd.

3. The method for producing a sintered R-T-B based magnet according to claim 1 , further comprising the step of loading a plurality of stirring aid members into the process chamber.

4. The method for producing a sintered R-T-B based magnet according to claim 3 , wherein during the RH supply and diffusion process, only the plurality of sintered R-T-B based magnet bodies, the plurality of alloy powder particles and the plurality of stirring aid members are contained as solids in the process chamber.

5. The method for producing a sintered R-T-B based magnet according to claim 1 , wherein the plurality of alloy powder particles each have a size of 38 μm or greater and 75 μm or less.

6. The method for producing a sintered R-T-B based magnet according to claim 5 , wherein the plurality of alloy powder particles each have a size of 38 μm or greater and 63 μm or less.

7. The method for producing a sintered R-T-B based magnet according to claim 1 , wherein the plurality of alloy powder particles is loaded into the process chamber at a ratio of 3% by weight or greater and 7% by weight or less with respect to the plurality of sintered R-T-B based magnet bodies.

8. The method for producing a sintered R-T-B based magnet according to claim 1 , wherein the plurality of alloy powder particles at least partially contain alloy powder particles having a new surface exposed.

9. The method for producing a sintered R-T-B based magnet according to claim 1 , wherein the plurality of alloy powder particles contain the heavy rare earth element RH at a content of 35 mass % or greater and 65 mass % or less.

10. The method for producing a sintered R-T-B based magnet according to claim 9 , wherein the plurality of alloy powder particles contain the heavy rare earth element RH at a content of 40 mass % or greater and 60 mass % or less.

11. The method for producing a sintered R-T-B based magnet according to claim 1 , wherein the heavy rare earth element RH is Tb.

12. The method for producing a sintered R-T-B based magnet according to claim 1 , wherein the plurality of alloy powder particles are produced by performing hydrogen pulverization on an alloy containing a heavy rare earth element RH (the heavy rare earth element RH is Tb and/or Dy) at a content of 35 mass % or greater and 50 mass % or less; and in a dehydrogenation step of the hydrogen pulverization, the alloy is heated to a temperature of 400° C. or higher and 550° C. or lower.

Assignees

• Hitachi Metals Ltd

Inventors

• YAMAGATA Ryouichi
• Kuniyoshi Futoshi

Classifications

• H01F1/0577

  sintered · CPC title

• C22C38/10

  containing cobalt · CPC title

• C22C38/005

  containing rare earths, i.e. Sc, Y, Lanthanides · CPC title

• H01F1/0551

  in the form of particles, e.g. rapid quenched powders or ribbon flakes · CPC title

• B22F2009/049

  by pulverising at particular temperature · CPC title