Method for manufacturing magnetic alloy powder having certain element distributions in thickness direction

Patent metadata

Field	Value
Publication number	US-11680306-B2
Application number	US-202217748901-A
Country	US
Kind code	B2
Filing date	May 19, 2022
Priority date	Feb 28, 2019
Publication date	Jun 20, 2023
Grant date	Jun 20, 2023

Abstract

A method for manufacturing magnetic alloy powder constituted by magnetic grains whose alloy phase is coated with an oxide film, includes: providing a material powder for magnetic alloy whose Fe content is 96.5 to 99 percent by mass and which also contains Si and at least one of non-Si elements (element M) that oxidize more easily than Fe; and heat-treating the material powder and thus forming an oxide film on a surface of each grain constituting the material powder, to obtain a magnetic alloy powder, wherein a content of Fe in the alloy phase is higher than in the material powder; and at a location in the oxide film where its content of Si is in element distributions in a film thickness direction is highest, the content of Si is higher than a content of Fe, and also higher than its content of element M, at the location.

First claim

We claim:

1. A method for manufacturing a magnetic alloy powder constituted by magnetic grains whose alloy phase is coated with an oxide film, comprising steps of:
providing a material powder for magnetic alloy whose Fe content is 96.5 to 99 percent by mass and which also contains Si and at least one of non-Si elements that oxidize more easily than Fe wherein the non-Si elements are collectively referred to as element M; and
heat-treating the material powder and thus forming an oxide film on a surface of each grain constituting the material powder, to obtain the magnetic alloy powder;
wherein the magnetic alloy powder is constituted in a manner that:
a content percentage of Fe in the alloy phase is higher than in the material powder; and
the oxide film contains Si, Fe, and element M, wherein at a location in the oxide film where its content of Si as expressed in percentage by mass is in element distributions in a film thickness direction is highest, the content of Si is higher than a content of Fe, and also higher than its content of element M, at the location.

2. The method for manufacturing the magnetic alloy powder according to claim 1 , wherein the oxide film in the magnetic alloy powder is constituted in a manner that its total content of Si is higher than its total content of Fe, and also higher than its total content of element M.

3. The method for manufacturing the magnetic alloy powder according to claim 1 , wherein the content of Fe in the alloy phase is 98 percent by mass or higher.

4. The method for manufacturing the magnetic alloy powder according to claim 1 , wherein the heat-treating step is performed in a manner that the oxide film contains element M.

5. The method for manufacturing the magnetic alloy powder according to claim 1 , wherein the heat-treating step is performed in a manner that the oxide film contains Si, and all of element M that is contained in the alloy phase, throughout the film in its entirety.

6. The method for manufacturing the magnetic alloy powder according to claim 1 , wherein the at least one of element M is at least one of Cr, Al, Ti, Zr, and Mg.

7. The method for manufacturing the magnetic alloy powder according to claim 1 , wherein the at least one of element M includes Cr.

8. A method for manufacturing a magnetic alloy powder constituted by magnetic grains whose alloy phase is coated with an oxide film, comprising steps of:
providing a material powder for magnetic alloy whose Fe content is 96.5 to 99 percent by mass and which also contains Si and at least one of non-Si elements that oxidize more easily than Fe wherein the non-Si elements are collectively referred to as element M; and
heat-treating the material powder and thus forming an oxide film on a surface of each grain constituting the material powder, to obtain the magnetic alloy powder;
wherein the magnetic alloy powder is constituted in a manner that:
a content percentage of Fe in the alloy phase is higher than in the material powder; and
at a location in the oxide film where its content of Si as expressed in percentage by mass is in element distributions in a film thickness direction is highest, the content of Si is higher than a content of Fe, and also higher than its content of element M, at the location,
wherein the heat-treating step is performed for 4 hours or longer at a temperature of 600 to 850° C. in an atmosphere of 5 to 500 ppm in oxygen concentration.

Assignees

• Taiyo Yuden Kk

Inventors

• Orimo Yoko
• Kashiwa Tomoo

Classifications

• C22C38/06 Primary

  containing aluminium · CPC title

• C22C38/14

  containing titanium or zirconium · CPC title

• C22C33/0264

  the maximum content of each alloying element not exceeding 5% · CPC title

• C22C38/18

  containing chromium · CPC title

• C22C38/02 Primary

  containing silicon · CPC title