WO2021256120A1 - Powder for dust magnetic core - Google Patents

Powder for dust magnetic core Download PDF

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Publication number
WO2021256120A1
WO2021256120A1 PCT/JP2021/017765 JP2021017765W WO2021256120A1 WO 2021256120 A1 WO2021256120 A1 WO 2021256120A1 JP 2021017765 W JP2021017765 W JP 2021017765W WO 2021256120 A1 WO2021256120 A1 WO 2021256120A1
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Prior art keywords
powder
mass
iron
chemical conversion
parts
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PCT/JP2021/017765
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French (fr)
Japanese (ja)
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里美 漆畑
啓文 北条
充洋 佐藤
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株式会社神戸製鋼所
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Priority to KR1020227038872A priority Critical patent/KR20220158841A/en
Priority to CN202180033825.1A priority patent/CN115515738A/en
Priority to SE2251265A priority patent/SE2251265A1/en
Publication of WO2021256120A1 publication Critical patent/WO2021256120A1/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/102Metallic powder coated with organic material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/17Metallic particles coated with metal
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24After-treatment of workpieces or articles
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/20Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/22Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/24Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated

Definitions

  • Patent Document 1 describes a composite powder having a composite oxide layer mainly composed of Fe-P and an organic layer containing Si in this order on the surface of the metal powder, and a lubricant is mixed. ing.
  • the powder magnetic core powder is laminated on the surface of the iron-based powder, the chemical conversion film formed on the surface of the iron-based powder, the surface treatment layer formed on the surface of the chemical conversion film, and the surface treatment layer.
  • a resin layer and a lubricant existing on the surface of the resin layer are provided.
  • the chemical conversion film, the surface treatment layer, and the resin layer are provided on the surface of the iron-based powder in this order. That is, in the powder for dust core, the chemical conversion film is directly formed on the surface of the iron-based powder, the surface treatment layer is directly formed on the surface of the chemical conversion film, and the resin layer is formed on the surface of the surface treatment layer.
  • the lubricant is present on the outermost surface of the powder magnetic core powder.
  • the surface treatment layer may become too thick and the density of the molded product may not be sufficiently increased.
  • the magnetic properties such as the bending strength and the magnetic flux density of the obtained dust core may be insufficient.
  • Heat treatment process In the heat treatment step, the molded product obtained in the compression molding step is annealed. In this heat treatment step, the lubricant contained in the molded product evaporates or thermally decomposes. Since the powder for dust core is provided with the chemical conversion film, the surface treatment layer, and the resin layer on the surface of the iron-based powder in this order, it can be obtained even when the lubricant is evaporated or thermally decomposed. The bending strength of the dust core can be sufficiently increased.

Abstract

The objective of the present invention is to provide a powder which is for a dust magnetic core, and which includes a lubricant and can increase the flexural strength of an obtained dust magnetic core. A powder for a dust magnetic core according to one aspect of the present invention is provided with: an iron-based powder; a chemical conversion coating formed on the surface of the iron-based powder; a surface treatment layer formed on the surface of the chemical conversion coating and containing a silane coupling agent; a resin layer laminated on the surface of the surface treatment layer and containing a silicone resin as a main component; and a lubricant present on the surface of the resin layer, wherein the chemical conversion coating includes at least one among phosphorus, nickel, and cobalt.

Description

圧粉磁心用粉末Powder for dust core
 本発明は、圧粉磁心用粉末に関する。 The present invention relates to a powder for a dust core.
 モータ、チョークコイル、リアクトル等のインダクタにおける磁心として圧粉磁心が使用される。この圧粉磁心には、機械的特性及び磁気的特性が共に優れていることが求められる。 A dust core is used as a magnetic core in inductors such as motors, choke coils, and reactors. The dust core is required to have excellent mechanical and magnetic properties.
 この圧粉磁心は、鉄基粉末を含む圧粉磁心用粉末を圧縮成形して製造される。圧粉磁心の機械的特性としては、抗折強度が大きいことが求められる。圧粉磁心の抗折強度は、密度を高めることで向上する。 This dust core is manufactured by compression molding powder for a powder core containing iron-based powder. As a mechanical property of the dust core, it is required to have a high bending strength. The bending strength of the dust core is improved by increasing the density.
 圧粉磁心の磁気的特性としては、鉄損が小さいこと、磁束密度が大きいこと等が求められる。鉄損を小さくするためには、鉄基粉末を電気絶縁層で被覆することが有効である。また、磁束密度を高めるためには、圧粉磁心の密度を高めることが有効である。 As the magnetic characteristics of the dust core, it is required that the iron loss is small and the magnetic flux density is large. In order to reduce the iron loss, it is effective to coat the iron-based powder with an electrically insulating layer. Further, in order to increase the magnetic flux density, it is effective to increase the density of the dust core.
 このように、圧粉磁心の機械的特性及び磁気的特性を高めるためには、鉄基粉末を電気絶縁層で被覆しつつ、圧粉磁心の密度を高めることが有効である。 As described above, in order to enhance the mechanical and magnetic properties of the dust core, it is effective to increase the density of the dust core while covering the iron-based powder with an electrically insulating layer.
 今日では、圧粉磁心の密度を高めるために金型の内面に潤滑剤を塗布することが提案されている。しかしながら、この構成によると、塗布作業が煩雑となり、塗布作業に要する時間が長くなるため、製造効率が低下する。 Today, it is proposed to apply a lubricant to the inner surface of the mold in order to increase the density of the dust core. However, according to this configuration, the coating work becomes complicated and the time required for the coating work becomes long, so that the manufacturing efficiency is lowered.
 このような観点から、圧粉磁心用粉末に予め潤滑剤を混合する技術が検討されている(特開2013-149659号公報、国際公開第2011/77694号参照)。 From this point of view, a technique for mixing a lubricant with a powder for a powder magnetic core in advance has been studied (see Japanese Patent Application Laid-Open No. 2013-149695 and International Publication No. 2011/77694).
特開2013-149659号公報Japanese Unexamined Patent Publication No. 2013-149695 国際公開第2011/77694号International Publication No. 2011/77694
 特許文献1には、金属粉末の表面に、Fe-Pを主体とする複合酸化物層と、Siを含む有機層とをこの順で有し、潤滑剤を混合してなる複合粉末が記載されている。 Patent Document 1 describes a composite powder having a composite oxide layer mainly composed of Fe-P and an organic layer containing Si in this order on the surface of the metal powder, and a lubricant is mixed. ing.
 特許文献2には、軟磁性粉末と無機絶縁粉末とに結着性絶縁樹脂を混合して得られた造粒物に、潤滑性樹脂を混合してなる圧粉磁心用粉末が記載されている。特許文献2には、無機絶縁粉末を構成する無機絶縁物質として、MgO、Al、TiO、CaOのうちの少なくとも1種を使用できることが記載されている。特許文献2には、軟磁性粉末と無機絶縁粉末との密着力を高めるためにシランカップリング剤を添加してもよいことが記載されている。 Patent Document 2 describes a powder for a powder magnetic core obtained by mixing a lubricating resin with a granulated product obtained by mixing a soft magnetic powder and an inorganic insulating powder with a binding insulating resin. .. Patent Document 2, as the inorganic insulating material constituting the inorganic insulating powder, MgO, it is described that at least one of Al 2 O 3, TiO 2, CaO can be used. Patent Document 2 describes that a silane coupling agent may be added in order to enhance the adhesion between the soft magnetic powder and the inorganic insulating powder.
 しかしながら、特許文献1及び特許文献2に記載されているように圧粉磁心用粉末に予め潤滑剤を混合すると、潤滑剤が蒸発又は熱分解した後にこの潤滑剤が存在していた領域が空隙となり、得られる圧粉磁心の密度が低下するおそれがある。その結果、圧粉磁心の抗折強度を十分に大きくすることができないおそれがある。 However, when a lubricant is mixed in advance with the dust core powder as described in Patent Document 1 and Patent Document 2, the region where the lubricant was present becomes a void after the lubricant is evaporated or thermally decomposed. , The density of the obtained dust core may decrease. As a result, the bending strength of the dust core may not be sufficiently increased.
 本発明は、このような事情に鑑みてなされたものであり、潤滑剤を含み、かつ得られる圧粉磁心の抗折強度を大きくすることができる圧粉磁心用粉末を提供することを目的とする。 The present invention has been made in view of such circumstances, and an object of the present invention is to provide a powder for a powder magnetic core, which contains a lubricant and can increase the bending strength of the obtained powder magnetic core. do.
 本発明の一態様に係る圧粉磁心用粉末は、鉄基粉末と、上記鉄基粉末の表面に形成される化成皮膜と、上記化成皮膜の表面に形成され、シランカップリング剤を含む表面処理層と、上記表面処理層の表面に積層され、シリコーン樹脂を主成分とする樹脂層と、上記樹脂層の表面に存在する潤滑剤とを備え、上記化成皮膜が、リンと、ニッケル及びコバルトのうちの少なくとも一方とを含む。 The powder for dust core according to one aspect of the present invention is formed on an iron-based powder, a chemical conversion film formed on the surface of the iron-based powder, and a surface treatment formed on the surface of the chemical conversion film and containing a silane coupling agent. A layer, a resin layer laminated on the surface of the surface treatment layer and having a silicone resin as a main component, and a lubricant present on the surface of the resin layer are provided, and the chemical conversion film is made of phosphorus, nickel and cobalt. Including at least one of them.
 当該圧粉磁心用粉末は、上記鉄基粉末の表面側に上記化成皮膜、上記表面処理層及び上記樹脂層がこの順で設けられており、上記樹脂層の表面に上記潤滑剤が存在している。当該圧粉磁心用粉末は、上記化成皮膜が、リンと、ニッケル及びコバルトのうちの少なくとも一方とを含んでおり、かつこの化成皮膜の表面に上記表面処理層を介して上記樹脂層が積層されているので、当該圧粉磁心用粉末を用いて形成される圧粉磁心の抗折強度を大きくすることができる。 The powder for dust core is provided with the chemical conversion film, the surface treatment layer and the resin layer in this order on the surface side of the iron-based powder, and the lubricant is present on the surface of the resin layer. There is. In the powder for dust core, the chemical conversion film contains phosphorus and at least one of nickel and cobalt, and the resin layer is laminated on the surface of the chemical conversion film via the surface treatment layer. Therefore, the bending strength of the dust core formed by using the powder for the powder core can be increased.
 上記鉄基粉末100質量部に対する上記シランカップリング剤の含有量としては0.05質量部以上0.30質量部以下が好ましく、かつ上記鉄基粉末100質量部に対する上記シリコーン樹脂の含有量としては0.05質量部以上0.30質量部以下が好ましい。このように、上記鉄基粉末100質量部に対する上記シランカップリング剤及び上記シリコーン樹脂の含有量が上記範囲内であることによって、上記圧粉磁心の抗折強度をより大きくすることができる。 The content of the silane coupling agent with respect to 100 parts by mass of the iron-based powder is preferably 0.05 parts by mass or more and 0.30 parts by mass or less, and the content of the silicone resin with respect to 100 parts by mass of the iron-based powder is It is preferably 0.05 parts by mass or more and 0.30 parts by mass or less. As described above, when the content of the silane coupling agent and the silicone resin with respect to 100 parts by mass of the iron-based powder is within the above range, the bending strength of the dust core can be further increased.
 上記鉄基粉末100質量部に対する上記潤滑剤の添加量としては0.20質量部以上0.40質量部以下が好ましい。このように、上記鉄基粉末100質量部に対する上記潤滑剤の添加量が上記範囲内であることによって、当該圧粉磁心用粉末を圧縮成形して得られる成形体の金型に対する滑り性を十分に高めつつ、上記圧粉磁心の抗折強度をより大きくすることができる。 The amount of the lubricant added to 100 parts by mass of the iron-based powder is preferably 0.20 parts by mass or more and 0.40 parts by mass or less. As described above, when the amount of the lubricant added to 100 parts by mass of the iron-based powder is within the above range, the slipperiness of the molded product obtained by compression molding the powder magnetic core powder is sufficient. The bending strength of the dust core can be further increased.
 なお、本発明において、「主成分」とは、質量換算において最も含有量が大きい成分を意味し、例えば含有量が50質量%以上の成分を意味する。 In the present invention, the "main component" means a component having the largest content in terms of mass, for example, a component having a content of 50% by mass or more.
 以上説明したように、本発明の一態様に係る圧粉磁心用粉末は、潤滑剤を含み、かつ得られる圧粉磁心の抗折強度を大きくすることができる。 As described above, the powder for dust core according to one aspect of the present invention contains a lubricant and can increase the bending strength of the obtained powder magnetic core.
 以下、本発明の実施の形態を詳説する。 Hereinafter, embodiments of the present invention will be described in detail.
[圧粉磁心用粉末]
 当該圧粉磁心用粉末は、鉄基粉末と、上記鉄基粉末の表面に形成される化成皮膜と、上記化成皮膜の表面に形成される表面処理層と、上記表面処理層の表面に積層される樹脂層と、上記樹脂層の表面に存在する潤滑剤とを備える。上記化成皮膜、上記表面処理層及び上記樹脂層は、上記鉄基粉末の表面にこの順で設けられている。すなわち、当該圧粉磁心用粉末は、上記鉄基粉末の表面に上記化成皮膜が直接形成され、上記化成皮膜の表面に上記表面処理層が直接形成され、上記表面処理層の表面に上記樹脂層が直接積層されている。上記潤滑剤は、当該圧粉磁心用粉末の最表面に存在している。
[Powder for dust core]
The powder magnetic core powder is laminated on the surface of the iron-based powder, the chemical conversion film formed on the surface of the iron-based powder, the surface treatment layer formed on the surface of the chemical conversion film, and the surface treatment layer. A resin layer and a lubricant existing on the surface of the resin layer are provided. The chemical conversion film, the surface treatment layer, and the resin layer are provided on the surface of the iron-based powder in this order. That is, in the powder for dust core, the chemical conversion film is directly formed on the surface of the iron-based powder, the surface treatment layer is directly formed on the surface of the chemical conversion film, and the resin layer is formed on the surface of the surface treatment layer. Are directly laminated. The lubricant is present on the outermost surface of the powder magnetic core powder.
(鉄基粉末)
 上記鉄基粉末は、軟磁性体である。上記鉄基粉末としては、純鉄粉、鉄基合金粉末、鉄基アモルファス粉末等が挙げられる。上記鉄基合金粉末としては、Fe-Al合金、Fe-Si合金、センダスト、パーマロイ等が挙げられる。上記鉄基粉末は、例えばアトマイズ法によって溶融鉄(又は溶融鉄合金)を微粒子とした後に還元し、その後粉砕することで製造される。この製造方法によると、上記鉄基粉末の平均粒子径は20μm以上250μm以下程度に制御できる。上記平均粒子径の下限としては、50μmが好ましい。上記平均粒子径の上限としては、150μmが好ましい。なお、「鉄基粉末の平均粒子径」とは、篩分け法で評価される粒度分布で累積粒度分布が50%になる粒径(メジアン径)を意味する。
(Iron-based powder)
The iron-based powder is a soft magnetic material. Examples of the iron-based powder include pure iron powder, iron-based alloy powder, and iron-based amorphous powder. Examples of the iron-based alloy powder include Fe—Al alloy, Fe—Si alloy, sendust, permalloy and the like. The iron-based powder is produced by, for example, atomizing a molten iron (or a molten iron alloy) into fine particles, reducing the particles, and then pulverizing the molten iron. According to this production method, the average particle size of the iron-based powder can be controlled to about 20 μm or more and 250 μm or less. The lower limit of the average particle size is preferably 50 μm. The upper limit of the average particle size is preferably 150 μm. The "average particle size of the iron-based powder" means a particle size (median size) at which the cumulative particle size distribution is 50% in the particle size distribution evaluated by the sieving method.
(化成皮膜)
 上記化成皮膜は、電気絶縁性を有する絶縁層である。上記化成皮膜は、P(リン)と、Ni(ニッケル)及びCo(コバルト)のうちの少なくとも一方とを含む。
(Chemical film)
The chemical conversion film is an insulating layer having electrical insulating properties. The chemical conversion film contains P (phosphorus) and at least one of Ni (nickel) and Co (cobalt).
 上記化成皮膜は、リンを含む化合物(例えば、オルトリン酸(HPO))が溶解した処理液を用いた化成処理によって生成されるリン酸系化成皮膜である。上記化成皮膜は、上記鉄基粉末由来のFe(鉄)元素を含んでいてもよい。 The chemical conversion film is a phosphoric acid-based chemical conversion film produced by a chemical conversion treatment using a treatment liquid in which a phosphorus-containing compound (for example, orthophosphoric acid (H 3 PO 4)) is dissolved. The chemical conversion film may contain an Fe (iron) element derived from the iron-based powder.
 上記化成皮膜はNiを含むことで得られる圧粉磁心の抗折強度を大きくしやすい。上記化成皮膜がNiを含む場合、上記鉄基粉末の表面に上記化成皮膜が形成された粉末100質量部に対するNiの含有量の下限としては、0.001質量部が好ましく、0.01質量部がより好ましい。一方、上記粉末100質量部に対するNiの含有量の上限としては、0.05質量部が好ましく、0.03質量部がより好ましい。上記含有量が上記範囲内であることで、上記化成皮膜の膜厚の均一化を図り(すなわち、上記化成皮膜に膜厚の極端に小さい箇所が生じることを抑制して)、当該圧粉磁心用粉末の絶縁性を確保できると共に、当該圧粉磁心用粉末を圧縮成形して得られる成形体(以下、単に「成形体」ともいう)の高密度化を図りやすい。また、当該圧粉磁心用粉末の耐熱性を高め、当該圧粉磁心用粉末の高温での熱処理を可能とし、得られる圧粉磁心の鉄損を低減しやすい。 The chemical conversion film easily increases the bending strength of the dust core obtained by containing Ni. When the chemical conversion film contains Ni, the lower limit of the Ni content with respect to 100 parts by mass of the powder having the chemical conversion film formed on the surface of the iron-based powder is preferably 0.001 part by mass, preferably 0.01 part by mass. Is more preferable. On the other hand, the upper limit of the Ni content with respect to 100 parts by mass of the powder is preferably 0.05 parts by mass, more preferably 0.03 parts by mass. When the content is within the above range, the film thickness of the chemical conversion film is made uniform (that is, the formation of an extremely small film thickness in the chemical conversion film is suppressed), and the dust core is formed. It is possible to secure the insulating property of the powder for powder, and it is easy to increase the density of the molded body (hereinafter, also simply referred to as “molded body”) obtained by compression molding the powder for dust core. Further, the heat resistance of the powder for the dust core is enhanced, the powder for the powder core can be heat-treated at a high temperature, and the iron loss of the obtained powder core can be easily reduced.
 上記化成皮膜がNiを含む場合、上記化成皮膜に含まれるPの含有量をM[mol]、Niの含有量をMNi[mol]とした場合、Pの含有量に対するNiの含有量の比(MNi/M)の下限としては、0.1が好ましく、0.15がより好ましい。一方、上記比(MNi/M)の上限としては、0.5が好ましく、0.4がより好ましい。上記比(MNi/M)が上記範囲内であることによって、上記化成皮膜の膜厚の均一化を図りやすい。 If the chemical conversion coating comprises a Ni, a content of P contained in the chemical conversion coating M P [mol], when the content of Ni and M Ni [mol], the content of Ni to the content of P As the lower limit of the ratio (M Ni / MP ), 0.1 is preferable, and 0.15 is more preferable. On the other hand, as the upper limit of the above ratio (M Ni / MP ), 0.5 is preferable, and 0.4 is more preferable. When the ratio (M Ni / MP ) is within the above range, it is easy to make the film thickness of the chemical conversion film uniform.
 上記化成皮膜がCoを含む場合、上記鉄基粉末の表面に上記化成皮膜が形成された粉末100質量部に対するCoの含有量の下限としては、0.005質量部が好ましい。一方、上記粉末100質量部に対するCoの含有量の上限としては、0.1質量部が好ましい。上記含有量が上記範囲内であることで、上記化成皮膜の膜厚の均一化を図り、当該圧粉磁心用粉末の絶縁性を確保できると共に、成形体の高密度化を図りやすい。また、当該圧粉磁心用粉末の耐熱性を高め、当該圧粉磁心用粉末の高温での熱処理を可能とし、得られる圧粉磁心の鉄損を低減しやすい。 When the chemical conversion film contains Co, the lower limit of the Co content with respect to 100 parts by mass of the powder in which the chemical conversion film is formed on the surface of the iron-based powder is preferably 0.005 part by mass. On the other hand, the upper limit of the Co content with respect to 100 parts by mass of the powder is preferably 0.1 part by mass. When the content is within the above range, the film thickness of the chemical conversion film can be made uniform, the insulating property of the powder for the dust core can be ensured, and the density of the molded product can be easily increased. Further, the heat resistance of the powder for the dust core is enhanced, the powder for the powder core can be heat-treated at a high temperature, and the iron loss of the obtained powder core can be easily reduced.
 上記化成皮膜中には、その他の成分として、Na(ナトリウム)、K(カリウム)、N(窒素)、S(硫黄)、Cl(塩素)等の元素が含まれていてもよい。これらの成分は、リンを含む化合物が溶解した処理液のpHを制御するため、又は上記処理液の反応を促進させるために必要に応じて添加され得る。 The chemical conversion film may contain elements such as Na (sodium), K (potassium), N (nitrogen), S (sulfur), and Cl (chlorine) as other components. These components may be added as necessary to control the pH of the treatment liquid in which the phosphorus-containing compound is dissolved, or to accelerate the reaction of the treatment liquid.
 上記化成皮膜は、上記その他の成分として、Kを含んでいることが好ましい。上記化成皮膜は、Kを含むことで、高温での熱処理中に皮膜中のO(酸素)とFeとが結合して半導体を形成することを抑制できる。これにより、熱処理に起因する比抵抗の低下及び抗折強度の低下を抑制することができる。 The chemical conversion film preferably contains K as the other component. By containing K, the chemical conversion film can suppress the formation of a semiconductor by combining O (oxygen) and Fe in the film during heat treatment at a high temperature. This makes it possible to suppress a decrease in resistivity and a decrease in bending strength due to heat treatment.
 上記化成皮膜が、上記その他の成分を含む場合、これらの成分毎の含有量としては、上記鉄基粉末100質量部に対し0.001質量部以上1.0質量部以下が好ましい。なお、上記化成皮膜は、上記その他の成分以外の成分についても、本発明の効果を阻害しない範囲内で含んでいてもよい。 When the chemical conversion film contains the other components, the content of each of these components is preferably 0.001 part by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the iron-based powder. The chemical conversion film may contain components other than the above other components as long as the effects of the present invention are not impaired.
 上記化成皮膜の膜厚の下限としては、1nmが好ましく、10nmがより好ましい。一方、上記化成皮膜の膜厚の上限としては、250nmが好ましく、50nmがより好ましい。上記膜厚が上記下限に満たないと、絶縁性が不十分となるおそれがある。逆に、上記膜厚が上記上限を超えると、得られる成形体の高密度化を十分に図り難くなるおそれがある。 The lower limit of the film thickness of the chemical conversion film is preferably 1 nm, more preferably 10 nm. On the other hand, the upper limit of the film thickness of the chemical conversion film is preferably 250 nm, more preferably 50 nm. If the film thickness does not reach the lower limit, the insulating property may be insufficient. On the contrary, if the film thickness exceeds the upper limit, it may be difficult to sufficiently increase the density of the obtained molded product.
(表面処理層)
 上記表面処理層は、電気絶縁性を有する絶縁層である。上記表面処理層は、シランカップリング剤を含む。シランカップリング剤は、シリコーン樹脂などの有機材料と反応して結合する官能基及び無機材料と反応して結合する官能基を共に有している。シランカップリング剤は上記化成皮膜と上記樹脂層との間に介在し、上記化成皮膜と上記樹脂層との密着性を高める。シランカップリング剤は、部分的に上記化成皮膜内に配置されていてもよい。
(Surface treatment layer)
The surface treatment layer is an insulating layer having electrical insulating properties. The surface treatment layer contains a silane coupling agent. The silane coupling agent has both a functional group that reacts with and binds to an organic material such as a silicone resin and a functional group that reacts and binds to an inorganic material. The silane coupling agent intervenes between the chemical conversion film and the resin layer to enhance the adhesion between the chemical conversion film and the resin layer. The silane coupling agent may be partially arranged in the chemical conversion film.
 シランカップリング剤としては、特に限定されないが、一般式:X-Si-(OR)(但し、Xは末端に極性基を有するアルキル基、Rは炭素数が1以上3以下のアルキル基であり、nは1以上3以下の整数)で表されるものを用いることができる。Xにおける極性基としては、アミノ基、ウレイド基、エポキシ基、チオール基、メタクリロキシ基等を有するものが挙げられ、中でもアミノ基を有するものが好ましい。 The silane coupling agent is not particularly limited, but the general formula: X—Si— (OR) n (where X is an alkyl group having a polar group at the terminal and R is an alkyl group having 1 or more and 3 or less carbon atoms. Yes, n can be an integer of 1 or more and 3 or less). Examples of the polar group in X include those having an amino group, a ureido group, an epoxy group, a thiol group, a methacryloxy group and the like, and among them, those having an amino group are preferable.
 上記鉄基粉末100質量部に対する上記シランカップリング剤の含有量の下限としては0.05質量部が好ましく、0.10質量部がより好ましい。一方、上記含有量の上限としては、0.30質量部が好ましく、0.20質量部がより好ましい。上記含有量が上記下限に満たないと、上記表面処理層を上記化成皮膜の表面に十分に形成することができず、上記化成皮膜及び上記樹脂層の密着性を十分に高めることができないおそれがある。逆に、上記含有量が上記上限を超えると、未反応のシランカップリング剤同士が縮合反応することに起因して上記化成皮膜及び上記樹脂層の密着性を十分に高めることができないおそれがある。また、上記含有量が上記上限を超えると、上記表面処理層が厚くなりすぎて、成形体密度を十分に大きくできないおそれがある。その結果、得られる圧粉磁心の抗折強度や磁束密度等の磁気特性が不十分となるおそれがある。 The lower limit of the content of the silane coupling agent with respect to 100 parts by mass of the iron-based powder is preferably 0.05 parts by mass, more preferably 0.10 parts by mass. On the other hand, as the upper limit of the content, 0.30 parts by mass is preferable, and 0.20 parts by mass is more preferable. If the content does not reach the lower limit, the surface treatment layer cannot be sufficiently formed on the surface of the chemical conversion film, and the adhesion between the chemical conversion film and the resin layer may not be sufficiently improved. be. On the contrary, if the content exceeds the upper limit, the adhesion between the chemical conversion film and the resin layer may not be sufficiently improved due to the condensation reaction between the unreacted silane coupling agents. .. On the other hand, if the content exceeds the upper limit, the surface treatment layer may become too thick and the density of the molded product may not be sufficiently increased. As a result, the magnetic properties such as the bending strength and the magnetic flux density of the obtained dust core may be insufficient.
(樹脂層)
 上記樹脂層は、電気絶縁性を有する絶縁層である。また同時に、上記樹脂層は、当該圧粉磁心用粉末の圧縮成形時(シリコーン樹脂の架橋・硬化反応終了時)に、他の圧粉磁心用粉末の樹脂層と結合する結合層である。
(Resin layer)
The resin layer is an insulating layer having electrical insulating properties. At the same time, the resin layer is a bonding layer that binds to another resin layer of the powder magnetic core powder at the time of compression molding of the powder magnetic core powder (at the end of the cross-linking / curing reaction of the silicone resin).
 上記樹脂層は、シリコーン樹脂を主成分とする。シリコーン樹脂は、上記表面処理層を構成するシランカップリング剤と結合することで、上記樹脂層と上記化成皮膜との密着性を高める。 The resin layer contains a silicone resin as a main component. The silicone resin binds to the silane coupling agent constituting the surface treatment layer to enhance the adhesion between the resin layer and the chemical conversion film.
 シリコーン樹脂としては、特に限定されないが、当該圧粉磁心用粉末のべとつきを抑えてハンドリング性を高める観点から、二官能性のD単位(RSiX:Xは加水分解性基)よりは、三官能性のT単位(RSiX:Xは加水分解性基)を多く持つものが好ましい。但し、四官能性のQ単位(SiX:Xは加水分解性基)が多く含まれていると、後述する予備硬化処理の際に他の圧粉磁心用粉末の樹脂層に含まれるシリコーン樹脂と強固に結着してしまうおそれがある。このような観点から、シリコーン樹脂のT単位の下限としては、60mol%が好ましく、80mol%がより好ましい。また、上記T単位としては、100mol%が最も好ましい。 The silicone resin is not particularly limited, but from the viewpoint of suppressing the stickiness of the powder for the powder magnetic core and improving the handling property, it is better than the bifunctional D unit (R 2 SiX 2 : X is a hydrolyzable group). Those having many trifunctional T units (RSiX 3 : X is a hydrolyzable group) are preferable. However, if a large amount of tetrafunctional Q units (SiX 4 : X is a hydrolyzable group) is contained, the silicone resin contained in the resin layer of the powder for the dust core during the pre-hardening treatment described later. There is a risk of tight binding. From this point of view, the lower limit of the T unit of the silicone resin is preferably 60 mol%, more preferably 80 mol%. The T unit is most preferably 100 mol%.
 上記各単位におけるRとしては、例えばメチル基及びフェニル基が挙げられる。シリコーン樹脂に含まれるRとしては、メチル基が50mol%以上であることが好ましく、メチル基が70mol%以上であることがより好ましい。さらに、上記シリコーン樹脂としては、上記Rとしてフェニル基を持たないメチルシリコーン樹脂が最も好ましい。なお、シリコーン樹脂におけるメチル基とフェニル基との比率、及び官能性については、FT-IR等で分析可能である。 Examples of R in each of the above units include a methyl group and a phenyl group. The R contained in the silicone resin preferably has a methyl group of 50 mol% or more, and more preferably 70 mol% or more of a methyl group. Further, as the silicone resin, a methyl silicone resin having no phenyl group as R is most preferable. The ratio of the methyl group to the phenyl group and the functionality of the silicone resin can be analyzed by FT-IR or the like.
 上記樹脂層におけるシリコーン樹脂の含有量の下限としては、50質量%であり、70質量%が好ましく、90質量%がより好ましい。また、上記樹脂層におけるシリコーン樹脂の含有量としては、100質量%が最も好ましい。上記含有量が上記下限に満たないと、得られる成形体の高密度化を十分に図り難くなるおそれがある。 The lower limit of the content of the silicone resin in the resin layer is 50% by mass, preferably 70% by mass, and more preferably 90% by mass. The content of the silicone resin in the resin layer is most preferably 100% by mass. If the content does not reach the lower limit, it may be difficult to sufficiently increase the density of the obtained molded product.
 上記鉄基粉末100質量部に対する上記シリコーン樹脂の含有量の下限としては、0.05質量部が好ましく、0.10質量部がより好ましい。一方、上記含有量の上限としては、0.30質量部が好ましく、0.20質量部がより好ましい。上記含有量が上記下限に満たないと、得られる圧粉磁心の抗折強度を十分に大きくし難くなるおそれがある。また、上記含有量が上記下限に満たないと、上記樹脂層の耐熱性が不十分となるおそれがある。逆に、上記含有量が上記上限を超えると、磁束密度の低下が大きくなるおそれがある。 The lower limit of the content of the silicone resin with respect to 100 parts by mass of the iron-based powder is preferably 0.05 parts by mass, more preferably 0.10 parts by mass. On the other hand, as the upper limit of the content, 0.30 parts by mass is preferable, and 0.20 parts by mass is more preferable. If the content does not reach the lower limit, it may be difficult to sufficiently increase the bending strength of the obtained dust core. Further, if the content does not reach the lower limit, the heat resistance of the resin layer may be insufficient. On the contrary, if the content exceeds the upper limit, the decrease in magnetic flux density may be large.
(潤滑剤)
 上記潤滑剤は、当該圧粉磁心用粉末を圧縮成形して成形体を形成する際における圧粉磁心用粉末同士の間、及び圧粉磁心用粉末と金型との間の摩擦抵抗を低減する。上記潤滑剤は、例えば粉末状である。
(lubricant)
The lubricant reduces the frictional resistance between the powder magnetic core powders and between the powder magnetic core powder and the mold when the powder for the powder magnetic core is compression-molded to form a molded body. .. The lubricant is, for example, in the form of powder.
 上記潤滑剤としては、例えば有機系潤滑剤及び無機系潤滑剤が挙げられ、これらを1種単独で又は2種以上を混合して用いることができる。 Examples of the lubricant include organic lubricants and inorganic lubricants, which can be used alone or in combination of two or more.
 上記有機系潤滑剤としては、例えば炭化水素系潤滑剤、脂肪酸系潤滑剤、高級アルコール系潤滑剤、脂肪族アミド系潤滑剤、金属石鹸系潤滑剤、エステル系潤滑剤等が挙げられる。 Examples of the organic lubricant include hydrocarbon lubricants, fatty acid lubricants, higher alcohol lubricants, aliphatic amide lubricants, metal soap lubricants, ester lubricants and the like.
 上記炭化水素系潤滑剤としては、例えば流動パラフィン、パラフィンワックス、合成ポリエチレンワックス等が挙げられる。上記脂肪酸系潤滑剤としては、例えばステアリン酸が挙げられる。上記高級アルコール系潤滑剤としては、例えばステアリルアルコールが挙げられる。上記脂肪族アミド系潤滑剤としては、例えばステアリン酸アミド、オレイン酸アミド、エルカ酸アミド等の脂肪酸アミドや、メチレンビスステアリン酸アミド、エチレンビスステアリン酸アミド等のアルキレン脂肪酸アミドなどが挙げられる。上記金属石鹸系潤滑剤としては、例えばステアリン酸亜鉛、ステアリン酸カルシウム、ステアリン酸リチウム等が挙げられる。上記エステル系潤滑剤としては、例えばステアリン酸モノグリセリドが挙げられる。 Examples of the hydrocarbon-based lubricant include liquid paraffin, paraffin wax, synthetic polyethylene wax and the like. Examples of the fatty acid-based lubricant include stearic acid. Examples of the higher alcohol-based lubricant include stearyl alcohol. Examples of the aliphatic amide-based lubricant include fatty acid amides such as stearic acid amides, oleic acid amides and erucic acid amides, and alkylene fatty acid amides such as methylene bisstearic acid amides and ethylene bisstearic acid amides. Examples of the metal soap-based lubricant include zinc stearate, calcium stearate, lithium stearate and the like. Examples of the ester-based lubricant include stearic acid monoglyceride.
 上記無機系潤滑剤としては、例えば密度が4.0g/cm以上の無機化合物を用いることができる。上記無機化合物としては、例えば二硫化モリブデン(MoS)、酸化亜鉛(ZnO)等が挙げられる。 As the inorganic lubricant, for example, an inorganic compound having a density of 4.0 g / cm 3 or more can be used. Examples of the inorganic compound include molybdenum disulfide (MoS 2 ) and zinc oxide (ZnO).
 上記鉄基粉末100質量部に対する上記潤滑剤の添加量の下限としては、0.20質量部が好ましく、0.25質量部がより好ましい。一方、上記含有量の上限としては、0.40質量部が好ましく、0.35質量部がより好ましい。上記含有量が上記下限に満たないと、金型等に対する当該圧粉磁心用粉末の滑り性を十分に高めることができないおそれがある。逆に、上記含有量が上記上限を超えると、当該圧粉磁心用粉末を用いて製造される圧粉磁心に上記潤滑剤に起因する空隙が形成されるおそれが高くなる。その結果、この圧粉磁心の高密度化を十分に図り難くなるおそれがある。 The lower limit of the amount of the lubricant added to 100 parts by mass of the iron-based powder is preferably 0.20 parts by mass, more preferably 0.25 parts by mass. On the other hand, as the upper limit of the content, 0.40 parts by mass is preferable, and 0.35 parts by mass is more preferable. If the content does not reach the lower limit, the slipperiness of the dust core powder to the mold or the like may not be sufficiently increased. On the contrary, when the content exceeds the upper limit, there is a high possibility that voids due to the lubricant are formed in the dust core produced by using the powder for the dust core. As a result, it may be difficult to sufficiently increase the density of the dust core.
<圧粉磁心用粉末の製造方法>
 当該圧粉磁心用粉末の製造方法は、鉄基粉末の表面に化成皮膜を形成する工程(化成皮膜形成工程)と、上記化成皮膜の表面に表面処理層を形成する工程(表面処理層形成工程)と、上記表面処理層の表面に樹脂層を積層する工程(樹脂層積層工程)と、上記樹脂層積層工程後の粉末と潤滑剤とを混合する工程(潤滑剤混合工程)とを備える。
<Manufacturing method of powder for dust core>
The method for producing the powder for the dust core is a step of forming a chemical conversion film on the surface of the iron-based powder (chemical conversion film forming step) and a step of forming a surface treatment layer on the surface of the chemical conversion film (surface treatment layer forming step). ), A step of laminating the resin layer on the surface of the surface treatment layer (resin layer laminating step), and a step of mixing the powder and the lubricant after the resin layer laminating step (lubricating agent mixing step).
(化成皮膜形成工程)
 上記化成皮膜形成工程では、例えばPを含む化合物と、Ni又はCoを含む化合物とを水性溶媒に溶解させて得た溶液(処理液)を上記鉄基粉末と混合したうえ、乾燥する。
(Chemical film formation process)
In the chemical conversion film forming step, for example, a solution (treatment liquid) obtained by dissolving a compound containing P and a compound containing Ni or Co in an aqueous solvent is mixed with the iron-based powder and then dried.
 Pを含む化合物としては、オルトリン酸(HPO)、(NHOH)・HPO等が挙げられる。Niを含む化合物としては、硝酸ニッケル(Ni(NO)、硫酸ニッケル、塩化ニッケル、炭酸ニッケル等が挙げられる。Coを含む化合物としては、Co(PO、Co(PO・8HO等が挙げられる。また、P及びNiを共に含む化合物として、ピロリン酸ニッケル(Ni7)等を用いることも可能である。 Examples of the compound containing P include orthophosphoric acid (H 3 PO 4 ), (NH 2 OH) 2 , H 2 PO 4 and the like. Examples of the compound containing Ni include nickel nitrate (Ni (NO 3 ) 2 ), nickel sulfate, nickel chloride, nickel carbonate and the like. As the compound containing Co, Co 3 (PO 4) 2, Co 3 (PO 4) 2 · 8H 2 O , and the like. It is also possible to use nickel pyrophosphate (Ni 2 P 2 O 7 ) or the like as a compound containing both P and Ni.
 上記処理液には、pH制御や反応促進のために、NaやKなどのアルカリ塩、アンモニア及びアンモニウム塩、硫酸塩、硝酸塩、リン酸塩等の添加剤が含まれてもよい。上記硫酸塩としては、例えば(NHOH)・HSO等が挙げられる。上記リン酸塩としては、例えばKHPO、NaHPO、(NHOH)・HPO等が挙げられる。これらのうち、KHPO及びNaHPOは処理液のpH制御に寄与し、(NHOH)・HSO及び(NHOH)・HPOは処理液の反応促進に寄与する。上記処理液が上述の添加剤を含む場合、得られる化成皮膜にNa、K、S等の元素が含まれることになる。上記化成皮膜がKを含む場合、当該圧粉磁心用粉末は、熱処理による比抵抗の低下及び抗折強度の低下を抑制しやすくなる。 The treatment liquid may contain additives such as alkali salts such as Na and K, ammonia and ammonium salts, sulfates, nitrates and phosphates for pH control and reaction promotion. Examples of the sulfate include (NH 2 OH) 2 , H 2 SO 4, and the like. Examples of the phosphate include KH 2 PO 4 , NaH 2 PO 4 , (NH 2 OH) 2 and H 2 PO 4 . Of these, KH 2 PO 4 and NaH 2 PO 4 contribute to the pH control of the treatment liquid, and (NH 2 OH) 2 · H 2 SO 4 and (NH 2 OH) 2 · H 2 PO 4 are the treatment liquid. Contributes to reaction promotion. When the treatment liquid contains the above-mentioned additives, the obtained chemical conversion film contains elements such as Na, K, and S. When the chemical conversion film contains K, the powder for dust core is likely to suppress a decrease in resistivity and a decrease in bending strength due to heat treatment.
 上記水性溶媒としては、水や、アルコール、ケトン等の親水性有機溶媒、及びこれらの混合物を用いることができる。上記水性溶媒中には、公知の界面活性剤が添加されていてもよい。 As the aqueous solvent, water, a hydrophilic organic solvent such as alcohol or a ketone, or a mixture thereof can be used. A known surfactant may be added to the aqueous solvent.
 上記化成皮膜形成工程では、例えば上記鉄基粉末に上記処理液を添加し、公知のミキサー、ボールミル、ニーダー、V型混合機、造粒機等で混合した後、大気中、減圧下又は真空下で、150℃以上250℃以下で乾燥する。これにより、上記鉄基粉末の表面に上記化成皮膜が形成される。上記化成皮膜形成工程では、上記乾燥後の粉末を目開き200μm以上600μm以下程度の篩に通過させることで、上記粉末の粒子径を制御してもよい。 In the chemical conversion film forming step, for example, the treatment liquid is added to the iron-based powder, mixed with a known mixer, ball mill, kneader, V-type mixer, granulator, or the like, and then in the air, under reduced pressure, or under vacuum. Then, it dries at 150 ° C. or higher and 250 ° C. or lower. As a result, the chemical conversion film is formed on the surface of the iron-based powder. In the chemical conversion film forming step, the particle size of the powder may be controlled by passing the dried powder through a sieve having an opening of 200 μm or more and 600 μm or less.
(表面処理層形成工程)
 上記表面処理層形成工程では、シランカップリング剤を溶媒中に溶解させた溶液を上記化成皮膜形成工程で形成された上記化成皮膜の表面に添加したうえ、乾燥する。
(Surface treatment layer forming process)
In the surface treatment layer forming step, a solution in which a silane coupling agent is dissolved in a solvent is added to the surface of the chemical conversion film formed in the chemical conversion film forming step, and then dried.
 シランカップリング剤を溶解させる溶媒としては、特に限定されるものではなく、例えば水や、アルコール、ケトン等の親水性有機溶媒、及びこれらの混合物を用いることができる。 The solvent for dissolving the silane coupling agent is not particularly limited, and for example, water, a hydrophilic organic solvent such as alcohol or a ketone, or a mixture thereof can be used.
(樹脂層積層工程)
 上記樹脂層積層工程では、シリコーン樹脂を溶媒中に溶解させた溶液を上記表面処理層形成工程で形成された上記表面処理層の表面に添加したうえ、乾燥する。
(Resin layer laminating process)
In the resin layer laminating step, a solution in which a silicone resin is dissolved in a solvent is added to the surface of the surface-treated layer formed in the surface-treated layer forming step, and then dried.
 シリコーン樹脂を溶解させる溶媒としては、例えばアルコールや、トルエン、キシレン等の石油系有機溶媒などを用いることができる。 As the solvent for dissolving the silicone resin, for example, alcohol, a petroleum-based organic solvent such as toluene or xylene, or the like can be used.
 上記樹脂層積層工程では、シリコーン樹脂を溶解させた上記溶媒が揮発する温度、かつシリコーン樹脂の硬化温度未満の温度で加熱し、上記溶媒を十分に揮発させることが好ましい。上記樹脂層積層工程における乾燥温度としては、上記溶媒の種類によっても異なるが、例えば60℃以上80℃以下が好ましい。上記樹脂層積層工程では、凝集ダマを除くために、乾燥後の粉末を目開き300μm以上600μm以下程度の篩に通過させることが好ましい。 In the resin layer laminating step, it is preferable to heat the solvent at a temperature at which the solvent in which the silicone resin is dissolved volatilizes and at a temperature lower than the curing temperature of the silicone resin to sufficiently volatilize the solvent. The drying temperature in the resin layer laminating step varies depending on the type of the solvent, but is preferably 60 ° C. or higher and 80 ° C. or lower, for example. In the resin layer laminating step, it is preferable to pass the dried powder through a sieve having an opening of 300 μm or more and 600 μm or less in order to remove agglomerated lumps.
 上記樹脂層積層工程では、上記乾燥後に、上記樹脂層が積層された粉末を加熱し、シリコーン樹脂の軟化過程を粉末状態で終了させる処理を行うことが好ましい(以下、シリコーン樹脂の軟化過程を粉末状態で終了させる処理を「予備硬化処理」ともいう)。上記予備硬化処理を行う方法としては、乾燥後の上記粉末をシリコーン樹脂の硬化温度近傍で短時間加熱する方法が挙げられる。上記予備硬化処理における加熱温度としては、例えば100℃以上200℃以下が挙げられる。上記予備硬化処理における加熱時間としては、例えば5分以上100分以下が挙げられる。また、上記予備硬化処理を行う方法としては、硬化剤を用いる方法を採用することも可能である。 In the resin layer laminating step, it is preferable to heat the powder on which the resin layer is laminated after the drying to end the softening process of the silicone resin in a powder state (hereinafter, the softening process of the silicone resin is powdered). The process of terminating in the state is also called "pre-curing process"). Examples of the method for performing the pre-curing treatment include a method of heating the dried powder in the vicinity of the curing temperature of the silicone resin for a short time. Examples of the heating temperature in the pre-hardening treatment include 100 ° C. or higher and 200 ° C. or lower. Examples of the heating time in the pre-hardening treatment include 5 minutes or more and 100 minutes or less. Further, as a method for performing the pre-curing treatment, it is also possible to adopt a method using a curing agent.
 上記予備硬化処理後の粉末同士は、完全に接着固化されていないため、容易に解砕可能である。シリコーン樹脂を予備硬化させた後、解砕することで流動性に優れる粉末が得られる。この粉末は、例えば100℃以上250℃以下程度の温間成形にて圧縮成形を行う際に金型に砂のように投入することができる。これにより、当該圧粉磁心用粉末の金型への投入を容易かつ確実に行うことができる。また、この予備硬化処理を行うことで、成形時に圧粉磁心用粉末同士の密着性を高めることでき、得られる成形体の高密度化を促進することができる。なお、上記予備硬化処理後の粉末は、目開き300μm以上600μm以下程度の篩に通過させ、粒子径を揃えておくことが好ましい。 The powders after the pre-hardening treatment are not completely adhered and solidified, so they can be easily crushed. By pre-curing the silicone resin and then crushing it, a powder having excellent fluidity can be obtained. This powder can be put into a mold like sand when compression molding is performed by, for example, warm molding at about 100 ° C. or higher and 250 ° C. or lower. As a result, the powder for the dust core can be easily and surely charged into the mold. Further, by performing this pre-hardening treatment, it is possible to enhance the adhesion between the powders for the dust core during molding, and it is possible to promote the high density of the obtained molded product. It is preferable that the powder after the pre-hardening treatment is passed through a sieve having an opening of 300 μm or more and 600 μm or less to have the same particle size.
<圧粉磁心の製造方法>
 当該圧粉磁心用粉末は、圧縮成形を行った後、熱処理を施すことで圧粉磁心に形成される。すなわち、当該圧粉磁心の製造方法は、当該圧粉磁心用粉末を圧縮成形する工程(圧縮成形工程)と、圧縮成形後の成形体を熱処理する工程(熱処理工程)とを備える。
<Manufacturing method of dust core>
The powder for a dust core is formed into a powder core by performing pressure molding and then heat treatment. That is, the method for producing the dust core includes a step of compression-molding the powder for the dust core (compression molding step) and a step of heat-treating the molded body after the compression molding (heat treatment step).
(圧縮成形工程)
 上記圧縮成形工程は、例えば金型を用いた公知の方法によって行うことが可能である。上記圧縮成形工程における面圧としては、490MPa以上1960MPa以下が好ましく、790MPa以上1180MPa以下がより好ましい。特に、上記圧縮成形工程では、980MPa以上の面圧で圧縮成形を行うことで、高密度の圧粉磁心を製造しやすい。上記圧縮成形工程は、室温成形及び温間成形のいずれによって行うことも可能であるが、温間成形を行う方が、高強度の圧粉磁心が得られるため好ましい。
(Compression molding process)
The compression molding step can be performed by, for example, a known method using a mold. The surface pressure in the compression molding step is preferably 490 MPa or more and 1960 MPa or less, and more preferably 790 MPa or more and 1180 MPa or less. In particular, in the compression molding step, it is easy to produce a high-density dust core by performing compression molding at a surface pressure of 980 MPa or more. The compression molding step can be performed by either room temperature molding or warm molding, but warm molding is preferable because a high-strength dust core can be obtained.
(熱処理工程)
 上記熱処理工程では、上記圧縮成形工程で得られた成形体を焼鈍する。この熱処理工程で、上記成形体に含まれる上記潤滑剤が蒸発又は熱分解する。当該圧粉磁心用粉末は、上記鉄基粉末の表面に上記化成皮膜、上記表面処理層及び上記樹脂層をこの順で備えているので、上記潤滑剤が蒸発又は熱分解した場合でも、得られる圧粉磁心の抗折強度を十分に大きくすることができる。
(Heat treatment process)
In the heat treatment step, the molded product obtained in the compression molding step is annealed. In this heat treatment step, the lubricant contained in the molded product evaporates or thermally decomposes. Since the powder for dust core is provided with the chemical conversion film, the surface treatment layer, and the resin layer on the surface of the iron-based powder in this order, it can be obtained even when the lubricant is evaporated or thermally decomposed. The bending strength of the dust core can be sufficiently increased.
 上記熱処理工程における熱処理温度の下限としては、500℃が好ましく、550℃がより好ましい。一方、上記熱処理工程における熱処理温度の上限としては、700℃が好ましく、650℃がより好ましい。上記熱処理温度が上記下限に満たないと、得られる圧粉磁心のヒステリシス損失を十分に低減できないおそれがある。逆に、上記熱処理温度が上記上限を超えると、上記鉄基粉末の表面を被覆する絶縁層(上記化成皮膜、上記表面処理層及び上記樹脂層)が劣化するおそれがある。 The lower limit of the heat treatment temperature in the heat treatment step is preferably 500 ° C., more preferably 550 ° C. On the other hand, as the upper limit of the heat treatment temperature in the heat treatment step, 700 ° C. is preferable, and 650 ° C. is more preferable. If the heat treatment temperature does not reach the lower limit, the hysteresis loss of the obtained dust core may not be sufficiently reduced. On the contrary, when the heat treatment temperature exceeds the upper limit, the insulating layer (the chemical conversion film, the surface treatment layer and the resin layer) covering the surface of the iron-based powder may be deteriorated.
 上記熱処理工程における熱処理時の雰囲気は、特に限定されるものではないが、窒素等の不活性ガス雰囲気が好ましい。上記熱処理工程における熱処理時間としては、得られる圧粉磁心の比抵抗が低下しない範囲内で設定可能である。上記熱処理時間の下限としては、例えば20分が好ましく、30分がより好ましく、60分がさらに好ましい。 The atmosphere at the time of heat treatment in the above heat treatment step is not particularly limited, but an atmosphere of an inert gas such as nitrogen is preferable. The heat treatment time in the heat treatment step can be set within a range in which the specific resistance of the obtained dust core does not decrease. As the lower limit of the heat treatment time, for example, 20 minutes is preferable, 30 minutes is more preferable, and 60 minutes is further preferable.
<圧粉磁心>
 上記圧粉磁心は、上記熱処理工程後、常温まで冷却することで得られる。上記圧粉磁心の抗折強度の下限としては、46MPaが好ましく、50MPaがより好ましく、60MPaがさらに好ましい。当該圧粉磁心用粉末は、上記鉄基粉末の表面に、上記化成皮膜、上記表面処理層及び上記樹脂層がこの順で設けられていることで、得られる圧粉磁心の抗折強度を上記下限以上に高めることができる。なお、上記抗折強度の上限としては、高いほど好ましいため特に限定されるものではないが、例えば100MPaとすることができる。なお、「抗折強度」とは、JIS-Z2511:2006に基づく値を意味する。
<Powder magnetic core>
The dust core is obtained by cooling to room temperature after the heat treatment step. As the lower limit of the bending strength of the dust core, 46 MPa is preferable, 50 MPa is more preferable, and 60 MPa is further preferable. In the powder for dust core, the chemical conversion film, the surface treatment layer, and the resin layer are provided on the surface of the iron-based powder in this order, so that the bending strength of the powder magnetic core can be obtained. It can be increased above the lower limit. The upper limit of the bending strength is not particularly limited because the higher it is, the more preferable it is, but it can be, for example, 100 MPa. The "anti-folding strength" means a value based on JIS-Z2511: 2006.
<利点>
 当該圧粉磁心用粉末は、上記化成皮膜が、リンと、ニッケル及びコバルトのうちの少なくとも一方とを含んでおり、かつこの化成皮膜の表面に上記表面処理層を介して上記樹脂層が積層されているので、当該圧粉磁心用粉末を用いて形成される圧粉磁心の抗折強度を大きくすることができる。
<Advantage>
In the powder for dust core, the chemical conversion film contains phosphorus and at least one of nickel and cobalt, and the resin layer is laminated on the surface of the chemical conversion film via the surface treatment layer. Therefore, the bending strength of the dust core formed by using the powder for the powder core can be increased.
[その他の実施形態]
 上記実施形態は、本発明の構成を限定するものではない。従って、上記実施形態は、本明細書の記載及び技術常識に基づいて上記実施形態各部の構成要素の省略、置換又は追加が可能であり、それらは全て本発明の範囲に属するものと解釈されるべきである。
[Other embodiments]
The above embodiment does not limit the configuration of the present invention. Therefore, the above-described embodiment can be omitted, replaced or added with components of each part of the above-described embodiment based on the description of the present specification and common general technical knowledge, and all of them are construed to belong to the scope of the present invention. Should be.
 以下、実施例に基づき本発明を詳述するが、この実施例の記載に基づいて本発明が限定的に解釈されるものではない。 Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limitedly interpreted based on the description of this Example.
[実施例]
[No.1~No.7]
(圧粉磁心用粉末の作製)
 鉄基粉末として、水アトマイズ法による純鉄粉で、不可避不純物としてC≦0.01質量%、Si≦0.03質量%、P≦0.02質量%、S≦0.01質量%を含み、150μm未満が16質量%、150μm以上180μm未満が41質量%、180μm以上250μm未満が42質量%、250μm以上が1質量%となる粒度分布の鉄基粉末を使用し、この鉄基粉末の表面にP及びNiを含む化成皮膜、シランカップリング剤を含む表面処理層及びシリコーン樹脂を主成分とする樹脂層をこの順で設けた後、樹脂層積層後の粉末と潤滑剤を混合した。具体的には、リン酸溶液として、水:50質量部、KHPO:35質量部、HPO:10質量部、(NHOH)・HPO:10質量部を混合したベース薬剤100mLに、ピロリン酸ニッケルと硝酸ニッケルとを合計で10質量部混合し、さらに皮膜形成後のリンの含有量と皮膜形成前のリンの含有量との差が0.04%となるように希釈した処理液50質量部を鉄基粉末1000質量部に混合した後、大気中で200℃、30分間乾燥し、目開き600μmの篩に通した(化成皮膜積層工程)。
[Example]
[No. 1 to No. 7]
(Preparation of powder for dust core)
As the iron-based powder, it is a pure iron powder by the water atomization method, and contains C ≦ 0.01% by mass, Si ≦ 0.03% by mass, P ≦ 0.02% by mass, and S ≦ 0.01% by mass as unavoidable impurities. , 16% by mass for less than 150 μm, 41% by mass for 150 μm or more and less than 180 μm, 42% by mass for 180 μm or more and less than 250 μm, and 1% by mass for 250 μm or more. A chemical conversion film containing P and Ni, a surface treatment layer containing a silane coupling agent, and a resin layer containing a silicone resin as a main component were provided in this order, and then the powder and the lubricant after laminating the resin layers were mixed. Specifically, as the phosphoric acid solution, water: 50 parts by mass, KH 2 PO 4 : 35 parts by mass, H 3 PO 4 : 10 parts by mass, (NH 2 OH) 2 · H 2 PO 4 : 10 parts by mass. A total of 10 parts by mass of nickel pyrophosphate and nickel nitrate were mixed with 100 mL of the mixed base drug, and the difference between the phosphorus content after film formation and the phosphorus content before film formation was 0.04%. 50 parts by mass of the treatment solution diluted so as to be mixed with 1000 parts by mass of the iron-based powder, dried in the air at 200 ° C. for 30 minutes, and passed through a sieve having an opening of 600 μm (chemical conversion film laminating step).
 続いて、ダウ・東レ株式会社製のシランカップリング剤「Z-6011」を水に溶解させた溶液を、鉄基粉末100質量部に対するシランカップリング剤の割合が表1の通りとなるように化成皮膜積層工程後の粉末に混合した後、125℃で30分間乾燥した(表面処理層形成工程)。次に、ダウ・東レ株式会社製のシリコーン樹脂「SR2400」をトルエンに溶解させた溶液を、鉄基粉末100質量部に対するシリコーン樹脂の含有量が表1の通りとなるように表面処理層形成工程後の粉末に混合した後、75℃で30分間乾燥した(樹脂層積層工程)。さらに、樹脂層積層工程後の粉末に潤滑剤を混合した。潤滑剤としては、ステアリン酸アミドと酸化亜鉛とを用い、鉄基粉末100質量部に対してステアリン酸アミドと酸化亜鉛とを表1の割合で添加した(潤滑剤混合工程)。 Subsequently, a solution prepared by dissolving the silane coupling agent "Z-6011" manufactured by Dow Toray Co., Ltd. in water was prepared so that the ratio of the silane coupling agent to 100 parts by mass of the iron-based powder is as shown in Table 1. After mixing with the powder after the chemical conversion film laminating step, it was dried at 125 ° C. for 30 minutes (surface treatment layer forming step). Next, a surface treatment layer forming step of a solution prepared by dissolving the silicone resin "SR2400" manufactured by Dow Toray Co., Ltd. in toluene so that the content of the silicone resin with respect to 100 parts by mass of the iron-based powder is as shown in Table 1. After mixing with the subsequent powder, it was dried at 75 ° C. for 30 minutes (resin layer laminating step). Further, a lubricant was mixed with the powder after the resin layer laminating step. As the lubricant, stearic acid amide and zinc oxide were used, and stearic acid amide and zinc oxide were added in the ratio shown in Table 1 to 100 parts by mass of the iron-based powder (lubricant mixing step).
(圧粉磁心サンプルの作製)
 潤滑剤混合工程後の粉末(圧粉磁心用粉末)を成形体に圧縮成形した。具体的には、常温の圧粉磁心用粉末を80℃に温めた金型に入れ、面圧800MPa(8.16ton/cm)で、18mm×32mm×12.5mmの直方体状の成形体に加圧成形した(圧縮成形工程)。その後、この成形体を窒素雰囲気下で、昇温速度10℃/分、到達温度600℃、保持時間30分で歪取り焼鈍を行った(熱処理工程)。この熱処理工程後の成形体を常温まで炉冷してNo.1~No.7のサンプルを得た。
(Preparation of dust core sample)
The powder (powder for dust core) after the lubricant mixing step was compression-molded into a molded body. Specifically, the powder for the powder magnetic core at room temperature is placed in a mold heated to 80 ° C., and the surface pressure is 800 MPa (8.16 ton / cm 2 ) to form a rectangular parallelepiped molded product of 18 mm × 32 mm × 12.5 mm. Pressure molded (compression molding process). Then, the molded product was subjected to strain removal annealing under a nitrogen atmosphere at a temperature rising rate of 10 ° C./min, an ultimate temperature of 600 ° C., and a holding time of 30 minutes (heat treatment step). After this heat treatment step, the molded product was cooled to room temperature to No. 1 to No. 7 samples were obtained.
[No.8]
(圧粉磁心用粉末の作製)
 鉄基粉末としてNo.1~No.7と同様の粉末を使用し、この鉄基粉末の表面にP及びNiを含む化成皮膜及びシリコーン樹脂を主成分とする樹脂層をこの順で設けた後、樹脂層積層後の粉末と潤滑剤を混合した。No.8では、シランカップリング剤を含む表面処理層を設けなかったこと、及び鉄基粉末100質量部に対するシリコーン樹脂及び潤滑剤の含有量を表1の通りとした以外、No.1~No.7と同様にして圧粉磁心用粉末を作製した。
[No. 8]
(Preparation of powder for dust core)
No. as iron-based powder. 1 to No. Using the same powder as in 7, a chemical conversion film containing P and Ni and a resin layer containing a silicone resin as a main component are provided on the surface of this iron-based powder in this order, and then the powder and lubricant after laminating the resin layer. Was mixed. No. In No. 8, except that the surface treatment layer containing the silane coupling agent was not provided and the contents of the silicone resin and the lubricant with respect to 100 parts by mass of the iron-based powder were as shown in Table 1. 1 to No. A powder for a dust core was prepared in the same manner as in 7.
(圧粉磁心サンプルの作製)
 潤滑剤混合工程後の粉末(圧粉磁心用粉末)をNo.1~No.7と同様にして成形体に圧縮成形した(圧縮成形工程)。その後、この成形体についてNo.1~No.7と同様の条件で歪取り焼鈍を行った(熱処理工程)。この熱処理工程後の成形体を常温まで炉冷してNo.8のサンプルを得た。
(Preparation of dust core sample)
The powder (powder for dust core) after the lubricant mixing step is No. 1 to No. The molded product was compression-molded in the same manner as in No. 7 (compression molding step). After that, No. 1 to No. Strain removal annealing was performed under the same conditions as in No. 7 (heat treatment step). After this heat treatment step, the molded product was cooled to room temperature to No. Eight samples were obtained.
<密度>
 No.1~No.8のサンプルの密度[g/cm]を求めた。密度は、各サンプルの質量及び大きさを実測し、計算によって求めた。この算出結果を表1に示す。
<Density>
No. 1 to No. The density of 8 samples [g / cm 3 ] was determined. The density was determined by measuring the mass and size of each sample and calculating. The calculation results are shown in Table 1.
<抗折強度>
 No.1~No.8のサンプルの抗折強度[MPa]をJIS Z-2511:2006に準拠して求めた。この測定結果を表1に示す。
<Anti-folding strength>
No. 1 to No. The bending strength [MPa] of 8 samples was determined according to JIS Z-2511: 2006. The measurement results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
<評価結果>
 表1に示すように、鉄基粉末の表面に、P及びNiを含む化成皮膜と、シランカップリング剤を含む表面処理層と、シリコーン樹脂を主成分とする樹脂層とがこの順で設けられ、かつ樹脂層の表面に潤滑剤が存在しているNo.1~No.7は、シランカップリング剤を含む表面処理層を備えないNo.8に比べて抗折強度が大きくなっている。特に、鉄基粉末100質量部に対するシランカップリング剤の含有量が0.10質量部以上であるNo.2~No.7は、No.8に対して抗折強度が極めて大きくなっている。
<Evaluation result>
As shown in Table 1, a chemical conversion film containing P and Ni, a surface treatment layer containing a silane coupling agent, and a resin layer containing a silicone resin as a main component are provided on the surface of the iron-based powder in this order. In addition, No. 1 in which the lubricant is present on the surface of the resin layer. 1 to No. No. 7 does not have a surface treatment layer containing a silane coupling agent. The anti-folding strength is larger than that of 8. In particular, No. 1 in which the content of the silane coupling agent with respect to 100 parts by mass of the iron-based powder is 0.10 parts by mass or more. 2-No. No. 7 is No. The anti-folding strength is extremely large with respect to 8.
 以上説明したように、本発明の一態様に係る圧粉磁心用粉末は、圧粉磁心の抗折強度を大きくするのに適している。 As described above, the powder for dust core according to one aspect of the present invention is suitable for increasing the bending strength of the powder core.

Claims (3)

  1.  鉄基粉末と、
     上記鉄基粉末の表面に形成される化成皮膜と、
     上記化成皮膜の表面に形成され、シランカップリング剤を含む表面処理層と、
     上記表面処理層の表面に積層され、シリコーン樹脂を主成分とする樹脂層と、
     上記樹脂層の表面に存在する潤滑剤と
     を備え、
     上記化成皮膜が、リンと、ニッケル及びコバルトのうちの少なくとも一方とを含む圧粉磁心用粉末。
    Iron-based powder and
    The chemical conversion film formed on the surface of the iron-based powder and
    A surface treatment layer formed on the surface of the chemical conversion film and containing a silane coupling agent, and
    A resin layer laminated on the surface of the surface treatment layer and containing a silicone resin as a main component,
    With the lubricant present on the surface of the resin layer,
    A powder for a dust core in which the chemical conversion film contains phosphorus and at least one of nickel and cobalt.
  2.  上記鉄基粉末100質量部に対する上記シランカップリング剤の含有量が0.05質量部以上0.30質量部以下であり、かつ上記鉄基粉末100質量部に対する上記シリコーン樹脂の含有量が0.05質量部以上0.30質量部以下である請求項1に記載の圧粉磁心用粉末。 The content of the silane coupling agent with respect to 100 parts by mass of the iron-based powder is 0.05 parts by mass or more and 0.30 parts by mass or less, and the content of the silicone resin with respect to 100 parts by mass of the iron-based powder is 0. The powder for a dust core according to claim 1, which is 05 parts by mass or more and 0.30 parts by mass or less.
  3.  上記鉄基粉末100質量部に対する上記潤滑剤の添加量が0.20質量部以上0.40質量部以下である請求項1又は請求項2に記載の圧粉磁心用粉末。
     
    The powder for dust core according to claim 1 or 2, wherein the amount of the lubricant added to 100 parts by mass of the iron-based powder is 0.20 parts by mass or more and 0.40 parts by mass or less.
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