Metal magnetic particle, inductor, method for manufacturing metal magnetic particle, and method for manufacturing metal magnetic core

Patent metadata

Field	Value
Publication number	US-11742141-B2
Application number	US-202117213121-A
Country	US
Kind code	B2
Filing date	Mar 25, 2021
Priority date	Mar 27, 2020
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

A metal magnetic particle provided with an oxide layer on a surface of an alloy particle containing Fe and Si. The oxide layer has a first oxide layer, a second oxide layer, and a third oxide layer from a side of the alloy particle. All of the first oxide layer, the second oxide layer, and the third oxide layer contain Si. Also, in line analysis of element content by using a scanning transmission electron microscope-energy dispersive X-ray spectroscopy, the first oxide layer is a layer having Fe content smaller than Si content in the alloy particle, the second oxide layer is a layer having Fe content larger than the Si content in the alloy particle, and the third oxide layer is a layer having Fe content smaller than the Si content in the alloy particle.

First claim

What is claimed is:

1. A metal magnetic core comprising:
metal magnetic particles, each metal magnetic particle comprising an oxide layer formed on a surface of an alloy particle containing Fe and Si, the oxide layer including a first oxide layer, a second oxide layer, and a third oxide layer from a side of the alloy particle, and all of the first oxide layer, the second oxide layer, and the third oxide layer containing Si, and
wherein
the metal magnetic particles are joined to each other by the oxide layer to form the metal magnetic core,
in line analysis of element content by using a scanning transmission electron microscope-energy dispersive X-ray spectroscopy,
the first oxide layer is a layer having Fe content smaller than Si content in the alloy particle,
the second oxide layer is a layer having Fe content larger than the Si content in the alloy particle, and
the third oxide layer is a layer having Fe content smaller than the Si content in the alloy particle.

2. The metal magnetic core according to claim 1 , wherein
a weight percentage of Si in the alloy particles is from 1.5 parts by weight to 8.0 parts by weight with respect to 100 parts by weight of a total weight of the Fe and the Si.

3. The metal magnetic core according to claim 1 , wherein
the alloy particles contain smaller than 1.0 part by weight of Cr with respect to 100 parts by weight of a total weight of the Fe and the Si.

4. An inductor comprising:
the metal magnetic core according to claim 1 .

5. The metal magnetic core according to claim 2 , wherein
the alloy particles contain smaller than 1.0 part by weight of Cr with respect to 100 parts by weight of a total weight of the Fe and the Si.

6. An inductor comprising:
the metal magnetic core according to claim 2 .

7. An inductor comprising:
the metal magnetic core according to claim 3 .

8. A method for manufacturing the metal magnetic core of claim 1 , the method comprising:
mixing raw material particles each of which has, on a surface of an alloy particle containing Fe and Si, an Si oxide film and an Fe oxide film from a side of the alloy particle with Si alkoxide and alcohol;
forming coating film forming particles each of which is formed with a coating film containing silicon oxide, by hydrolyzing and drying the Si alkoxide;
molding the coating film forming particles; and
forming an oxide layer on a surface of each of the alloy particles by performing heat treatment on a molded body of the coating film forming particles in an oxidizing atmosphere, wherein
an average thickness of the coating film is from larger than 14 nm to 30 nm, and
a temperature of the heat treatment is from 600° C. to lower than 750° C.

9. The method for manufacturing the metal magnetic core according to claim 8 , wherein
the molding includes laminating and pressing a green sheet containing the coating film forming particles.

10. The method for manufacturing the metal magnetic core according to claim 8 , wherein
the Si alkoxide is tetraethoxysilane.

11. The method for manufacturing the metal magnetic core according to claim 9 , wherein
the Si alkoxide is tetraethoxysilane.

12. The metal magnetic core according to claim 1 , wherein
the second oxide layer has a larger maximum content of Si than the third oxide layer.

13. The metal magnetic core according to claim 1 , wherein
the third oxide layer contains Fe.

14. The metal magnetic core according to claim 13 , wherein
a ratio of the Fe content to the Si content at the point where the Si content of the third oxide layer takes the local maximum value is equal to or larger than about 0.1 and equal to or smaller than about 0.5.

Assignees

• Murata Manufacturing Co

Inventors

• Ishida Takuya
• Yamamoto Makoto
• Uji Katsutoshi
• Ishida Yuya
• Odahara Mitsuru

Classifications

• H01F1/33 Primary

  mixtures of metallic and non-metallic particles; metallic particles having oxide skin · CPC title

• H01F41/0246 Primary

  Manufacturing of magnetic circuits by moulding or by pressing powder (magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36) · CPC title

• B22F1/142

  Thermal or thermo-mechanical treatment · CPC title

• B22F1/16

  Metallic particles coated with a non-metal (coated with lubricating or binding agents or with organic material B22F1/10) · CPC title

• H01F1/14766

  Fe-Si based alloys · CPC title