Process for producing composite magnetic material, dust core formed from same, and process for producing dust core

• US 8,328,955 B2
• Filed: 01/14/2010
• Issued: 12/11/2012
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Wakabayashi, Yuya, Takahashi, Takeshi, Matsutani, Nobuya
• Primary Examiner(s): SHEEHAN, JOHN P
• Application Number:
  US13/144,592
• Publication Number:
  US 20110272622A1
• Time in Patent Office: 1,062 Days
• Field of Search: None
• US Class Current: 148/104
• CPC Class Codes: B22F 2301/052 Aluminium
• CPC Class Codes: B22F 2301/15 Nickel or cobalt
• CPC Class Codes: B22F 2301/35 Iron
• CPC Class Codes: B22F 2302/25 Oxide
• CPC Class Codes: B22F 2302/35 Complex boride, carbide, carbonitride, nitride, oxide or oxynitride
• CPC Class Codes: B22F 2303/01 Main component
• CPC Class Codes: B22F 2303/05 Compulsory alloy component
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: C21D 6/008 containing Si
• CPC Class Codes: C21D 8/12 during manufacturing of articles with special electromagnetic properties
• CPC Class Codes: C22C 19/03 based on nickel
• CPC Class Codes: C22C 2202/02 Magnetic
• CPC Class Codes: C22C 30/00 Alloys containing less than 50% by weight of each constituent
• CPC Class Codes: C22C 33/0228 comprising other non-metallic compounds or more than 5% of graphite
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C22C 38/08 containing nickel C22C38/105 takes precedence
• CPC Class Codes: C22C 38/34 with more than 1.5% by weight of silicon
• CPC Class Codes: C22F 1/10 of nickel or cobalt or alloys based thereon
• CPC Class Codes: H01F 1/1475 the particles being insulated
• CPC Class Codes: H01F 1/14766 : Fe-Si based alloys
• CPC Class Codes: H01F 1/14791 : Fe-Si-Al based alloys, e.g. Sendust
• CPC Class Codes: H01F 1/24 : the particles being insulated
• CPC Class Codes: H01F 1/33 : mixtures of metallic and non-metallic particles; metallic particles having oxide skin
• CPC Class Codes: H01F 3/08 : made from powder powder coatings on sheets H01F3/02; on strips or ribbons H01F3/04; on wires H01F3/06
• CPC Class Codes: H01F 41/0246 : 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

Abstract

A composite magnetic material is manufactured having magnetic properties that can excellently cope with the decreasing size and increasing electric current of magnetic elements, such as choke coils, and can be used in a high frequency range, a dust core using the composite magnetic material, and a method of manufacturing the same. The dust core includes magnetic metal powder and an insulating material, in which the magnetic metal powder has a Vickers hardness (Hv) of 230 ≦ Hv≦ 1000, the insulating material has a compressive strength of 10000 kg/cm² or lower and is in a mechanical collapsed state, and the insulating material in a mechanical collapsed state is interposed in the magnetic metal powder.

Claims

1. A dust core, comprising:

a magnetic metal powder; and

an insulating material,

wherein the magnetic metal powder has a Vickers hardness (Hv) of 230 ≦

Hv≦

1000;

the insulating material has a compressive strength of 10000 kg/cm² or lower and is in a mechanical collapsed state; and

the insulating material in a mechanical collapsed state is interposed in the magnetic metal powder.

2. The dust core of claim 1,

wherein the magnetic metal powder includes at least one of Fe—

Ni-based, Fe—

Si—

Al-based, Fe—

Si-based, Fe—

Si—

Cr-based, and Fe-based magnetic metal powders.

3. The dust core according to claim 1,

wherein an average particle diameter of the magnetic metal powder is 1 μ

m to 100 μ

m.

4. The dust core according to claim 1,

wherein the insulating material includes at least one of inorganic substances of h-BN, MgO, mullite (3Al₂O₃.2SiO₂), steatite (MgO.SiO₂), forsterite (2MgO.SiO₂), cordierite (2MgO.2Al₂O₃.5SiO₂), and zircon (ZrO₂.SiO₂).

5. The dust core according to claim 1,

wherein the insulating material has a melting point of 1200°

C. or higher.

6. The dust core according to claim 1,

wherein a packing factor of the magnetic metal powder is 80% or higher when computed by volume.

7. A method of manufacturing a dust core, comprising:

a step in which an insulating material having a compressive strength of 10000 kg/cm² or lower is dispersed in a magnetic metal material having a Vickers hardness (Hv) of 230 ≦

Hv ≦

1000 ,

a step in which a composite magnetic material obtained in the dispersing step is pressed so as to form a compact; and

a step in which a thermal treatment is performed on the compact,

wherein, in the step of forming the compact, the insulating material is made to be in a mechanical collapsed state.

8. The method of manufacturing a dust core according to claim 7,

wherein, in the step of performing the thermal treatment on the compact, the compact is annealed in a non-oxidizing atmosphere at a temperature of 700°

C. to 1150°

C.

9. The method of manufacturing a dust core according to claim 7,

wherein the magnetic metal powder includes at least one of Fe—

Ni-based, Fe—

Si—

Al-based, Fe—

Si-based, Fe—

Si—

Cr-based, and Fe-based magnetic metal powder.

10. The method of manufacturing a dust core according to claim 7,

wherein the average particle diameter of the magnetic metal powder is 1 μ

m to 100 μ

m.

11. The method of manufacturing a dust core according to claim 7,

wherein the insulating material includes at least one of inorganic substances of h-BN, MgO, mullite (3Al₂O₃.2SiO₂), steatite (MgO.SiO₂), forsterite (2MgO.SiO₂), cordierite (2MgO.2Al₂O₃.5SiO₂), and zircon (ZrO₂.SiO₂).

12. The method of manufacturing a dust core according to claim 7,

wherein the insulating material has a melting point of 1200°

C. or higher.

13. The method of manufacturing a dust core according to claim 7,

wherein the packing factor of the magnetic metal powder is 80% or higher when computed by volume.

14. The method of manufacturing a dust core, according to claim 7,

wherein an incorporated amount of the insulating material is 1% to 10% by volume when the volume of the magnetic metal powder is set to 100% by volume.