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JP4856602B2 - Iron-based soft magnetic powder for dust core and dust core - Google Patents

Iron-based soft magnetic powder for dust core and dust core Download PDF

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JP4856602B2
JP4856602B2 JP2007202194A JP2007202194A JP4856602B2 JP 4856602 B2 JP4856602 B2 JP 4856602B2 JP 2007202194 A JP2007202194 A JP 2007202194A JP 2007202194 A JP2007202194 A JP 2007202194A JP 4856602 B2 JP4856602 B2 JP 4856602B2
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soft magnetic
iron
magnetic powder
dust core
powder
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JP2009038256A (en
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宏幸 三谷
宣明 赤城
啓文 北条
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Kobe Steel Ltd
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Priority to US12/670,750 priority patent/US8409707B2/en
Priority to CN2008801000497A priority patent/CN101755313B/en
Priority to PCT/JP2008/062018 priority patent/WO2009013979A1/en
Priority to TW097127978A priority patent/TWI406305B/en
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00Cores, Yokes, or armatures
    • H01F3/08Cores, Yokes, or armatures made from powder
    • 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
    • B22F1/16Metallic particles coated with a non-metal
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C33/00Making ferrous alloys
    • C22C33/02Making ferrous alloys by powder metallurgy
    • 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
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206Manufacturing of magnetic cores by mechanical means
    • H01F41/0246Manufacturing of magnetic circuits by moulding or by pressing powder
    • 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
    • B22F2998/00Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10Processes characterised by the sequence of their steps
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C2202/00Physical properties
    • C22C2202/02Magnetic
    • 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
    • H01F1/26Magnets 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 by macromolecular organic substances

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)
  • Soft Magnetic Materials (AREA)

Description

本発明は、特に機械的強度と電気絶縁性に優れた圧粉磁心用鉄基軟磁性粉末および圧粉磁心に関するものである。   The present invention relates to an iron-based soft magnetic powder for dust cores and a dust core particularly excellent in mechanical strength and electrical insulation.

近年、交流磁界で使用され磁気特性にも優れ、且つ、三次元形状の自由度も高いことを特徴にした電磁気部品として、軟磁性粉末を圧縮成形した圧粉磁心が使用されつつある。例えば、周波数が50kHz程度以下で使用されるモータやトランス用のコア材(圧粉磁心)として、低鉄損と高磁束密度を目的に、以下のような軟磁性粉末を圧縮成形し、その後歪取り焼鈍する構成のものが知られている(特許文献1)。また、この圧粉磁心用の軟磁性粉末は、圧縮性に優れ、且つ、高い絶縁性を有することを目的に、純鉄粉の表面を鉄酸化物で被覆し、この鉄酸化物の表面を酸化物、炭酸塩及び硫酸塩のうちから選んだ少なくとも一種の絶縁層で被覆し、さらにこの絶縁層の表面をシリコーン樹脂層で被覆した構成のものである(特許文献1)。
特開2006−233295号公報
2. Description of the Related Art In recent years, a powder magnetic core obtained by compression-molding soft magnetic powder is being used as an electromagnetic component that is used in an alternating magnetic field and has excellent magnetic characteristics and a high degree of freedom in three-dimensional shape. For example, the following soft magnetic powder is compression-molded for the purpose of low iron loss and high magnetic flux density as a core material (powder magnetic core) for motors and transformers used at a frequency of about 50 kHz or less, and then strained. The thing of the structure which removes and anneals is known (patent document 1). In addition, the soft magnetic powder for a dust core is coated with iron oxide on the surface of pure iron powder for the purpose of excellent compressibility and high insulation properties. The structure is such that at least one insulating layer selected from oxides, carbonates and sulfates is coated, and the surface of this insulating layer is further coated with a silicone resin layer (Patent Document 1).
JP 2006-233295 A

上記従来の圧粉磁心は、ヒステリシス損を低減させるために、高温で歪取り焼鈍を行う。また、この高温での熱処理により、今度は電気絶縁性が低下し比抵抗の低下をもたらし易くなるのを抑制するために、純鉄粉の表面を被覆する鉄酸化物とこの鉄酸化物の表面を被覆する絶縁層を設けた後、以下のような高温での熱処理をわざわざ付加しなければならないといった課題を有していた。この高温での熱処理は、結合強化処理と称し、非酸化性雰囲気中、500〜1200℃、20〜240分の加熱処理を行わなければならないものである。   The conventional dust core performs strain relief annealing at a high temperature in order to reduce hysteresis loss. In addition, in order to suppress the heat insulation at this high temperature, which in turn reduces the electrical insulation and easily reduces the specific resistance, the iron oxide covering the surface of the pure iron powder and the surface of the iron oxide After providing the insulating layer covering the film, there is a problem that the following high-temperature heat treatment must be added. This heat treatment at a high temperature is referred to as a bond strengthening treatment, and heat treatment must be performed at 500 to 1200 ° C. for 20 to 240 minutes in a non-oxidizing atmosphere.

本発明は、上記課題を解決するものであり、結合強化処理と称する高温での熱処理を付加せず、且つ、高密度に成形した場合にも、機械的強度に優れ、鉄基軟磁性粉末粒子間を効果的に絶縁することができ、さらに、歪取り焼鈍を行っても電気絶縁性を良好に維持できるような熱的安定性に優れた圧粉磁心用鉄基軟磁性粉末およびこの粉末を用いた圧粉磁心を提供することを目的とする。   The present invention solves the above-mentioned problems, and does not add a heat treatment at a high temperature called a bond strengthening process, and has excellent mechanical strength even when molded at a high density, and iron-based soft magnetic powder particles An iron-based soft magnetic powder for dust cores with excellent thermal stability that can effectively insulate the gap and maintain good electrical insulation even after strain relief annealing, and this powder It aims at providing the used powder magnetic core.

上記目的を達成するために、本発明の請求項1に記載の発明は、鉄基(但し、Fe−Co系合金、Fe−Ni−Co系合金を除く)軟磁性粉末表面に、FeとCoより成る被膜と、Coを含まないリン酸系化成被膜と、シリコーン樹脂被膜とが、この順に形成されていることを特徴とする圧粉磁心用鉄基軟磁性粉末である。これにより、結合強化処理と称する高温での熱処理を付加せず、且つ、高密度に成形した場合にも、機械的強度に優れ、鉄基軟磁性粉末粒子間を効果的に絶縁することができ、さらに、歪取り焼鈍を行っても電気絶縁性を良好に維持できるような熱的安定性に優れた圧粉磁心用鉄基軟磁性粉末を実現できる。また、リン酸系化成被膜がCoを含まないため、歪取り焼鈍をより高温で行っても、高い比抵抗を維持できる。 In order to achieve the above object, the invention according to claim 1 of the present invention is characterized in that Fe and Co are formed on the surface of an iron-based (excluding Fe-Co alloy and Fe-Ni-Co alloy) soft magnetic powder. An iron-based soft magnetic powder for a dust core, characterized in that a coating film, a phosphoric acid-based chemical conversion film not containing Co, and a silicone resin film are formed in this order. This makes it possible to effectively insulate the iron-based soft magnetic powder particles even when molded at a high density without applying a heat treatment at a high temperature called a bond strengthening treatment. Furthermore, it is possible to realize an iron-based soft magnetic powder for a dust core that is excellent in thermal stability so that electrical insulation can be maintained well even if strain relief annealing is performed. Moreover, since the phosphoric acid-based chemical conversion film does not contain Co, a high specific resistance can be maintained even if the strain relief annealing is performed at a higher temperature.

請求項に記載の発明は、請求項1に記載の発明において、FeとCoより成る被膜の膜厚が、1〜10nmであることを特徴とするものである。これにより、FeとCoより成る被膜の形成性を維持しつつ鉄基軟磁性粉末の変形の自由度を確保できるため、成形時の前記粉末の密度が上がり高磁束密度を実現できる。 The invention according to claim 2 is characterized in that, in the invention according to claim 1, the film thickness of the coating made of Fe and Co is 1 to 10 nm. As a result, the degree of freedom of deformation of the iron-based soft magnetic powder can be secured while maintaining the formability of the film made of Fe and Co, so that the density of the powder at the time of molding can be increased and a high magnetic flux density can be realized.

請求項に記載の発明は、請求項1または2に記載の発明において、シリコーン樹脂被膜を形成するためのシリコーン樹脂は、三官能性のメチルシリコーン樹脂であることを特徴とするものである。これにより、成形時の前記粉末のハンドリング性が向上する。 The invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2 , the silicone resin for forming the silicone resin film is a trifunctional methyl silicone resin. Thereby, the handleability of the powder during molding is improved.

請求項に記載の発明は、請求項1乃至のいずれかに記載の圧粉磁心用鉄基軟磁性粉末を成形して得られた圧粉磁心である。このような磁心を例えば周波数が50kHz程度以下で使用するならば、モータやトランス用のコア材としての低鉄損と高磁束密度を実現でき、ひいてはモータやトランスの性能を向上させることができる。 The invention according to claim 4 is a dust core obtained by molding the iron-based soft magnetic powder for dust core according to any one of claims 1 to 3 . If such a magnetic core is used at a frequency of about 50 kHz or less, for example, a low iron loss and a high magnetic flux density can be realized as a core material for a motor or transformer, and the performance of the motor or transformer can be improved.

以上のように、本発明は、鉄基(但し、Fe−Co系合金、Fe−Ni−Co系合金を除く)軟磁性粉末表面に、FeとCoより成る被膜と、Coを含まないリン酸系化成被膜と、シリコーン樹脂被膜とが、この順に形成されていることを特徴とする圧粉磁心用鉄基軟磁性粉末であるため、結合強化処理と称する高温での熱処理を付加せず、且つ、高密度に成形した場合にも、機械的強度に優れ、鉄基軟磁性粉末粒子間を効果的に絶縁することができ、さらに、歪取り焼鈍を行っても電気絶縁性を良好に維持できるような熱的安定性に優れた圧粉磁心用鉄基軟磁性粉末を実現できる。また、リン酸系化成被膜がCoを含まないため、歪取り焼鈍をより高温で行っても、高い比抵抗を維持できる。 As described above, the present invention provides an iron-based (excluding Fe-Co alloy and Fe-Ni-Co alloy) soft magnetic powder surface, a coating made of Fe and Co, and phosphoric acid not containing Co. Since the chemical conversion coating and the silicone resin coating are formed in this order, the iron-based soft magnetic powder for the dust core is not subjected to heat treatment at a high temperature called bond strengthening treatment, and Even when molded at high density, it has excellent mechanical strength, can effectively insulate between iron-based soft magnetic powder particles, and can maintain good electrical insulation even after strain relief annealing Thus, an iron-based soft magnetic powder for a dust core having excellent thermal stability can be realized. Moreover, since the phosphoric acid-based chemical conversion film does not contain Co, a high specific resistance can be maintained even if the strain relief annealing is performed at a higher temperature.

また、本発明は、上記圧粉磁心用鉄基軟磁性粉末を成形して得られた圧粉磁心であるため、このような磁心を例えば周波数が50kHz程度以下で使用するならば、モータやトランス用のコア材として低鉄損と高磁束密度を実現でき、ひいてはモータやトランスの性能を向上させることができる。   Further, since the present invention is a dust core obtained by molding the iron-based soft magnetic powder for a dust core, if such a core is used at a frequency of about 50 kHz or less, for example, a motor or transformer As a core material, it is possible to realize a low iron loss and a high magnetic flux density, thereby improving the performance of a motor and a transformer.

以下、本発明について、実施形態を例示しつつ、さらに詳細に説明する。   Hereinafter, the present invention will be described in more detail while illustrating embodiments.

(本発明に係る圧粉磁心用鉄基軟磁性粉末およびこの粉末を用いた圧粉磁心の構成)
本発明に係る圧粉磁心用鉄基軟磁性粉末は、鉄基(但し、Fe−Co系合金、Fe−Ni−Co系合金を除く)軟磁性粉末表面に、FeとCoより成る被膜と、Coを含まないリン酸系化成被膜と、シリコーン樹脂被膜とが、この順に形成されていることを特徴とする圧粉磁心用鉄基軟磁性粉末である。これにより、結合強化処理と称する高温での熱処理を付加せず、且つ、高密度に成形した場合にも、機械的強度に優れ、鉄基軟磁性粉末粒子間を効果的に絶縁することができ、さらに、歪取り焼鈍を行っても電気絶縁性を良好に維持できるような熱的安定性に優れた圧粉磁心用鉄基軟磁性粉末を実現できる。また、リン酸系化成被膜がCoを含まないため、歪取り焼鈍をより高温で行っても、高い比抵抗を維持できる。
(Configuration of iron-based soft magnetic powder for dust core and dust core using this powder according to the present invention)
An iron-based soft magnetic powder for a dust core according to the present invention has a coating made of Fe and Co on an iron-based (excluding Fe-Co alloy and Fe-Ni-Co alloy) soft magnetic powder surface, An iron-based soft magnetic powder for a dust core, in which a phosphoric acid-based chemical conversion film not containing Co and a silicone resin film are formed in this order. This makes it possible to effectively insulate the iron-based soft magnetic powder particles even when molded at a high density without applying a heat treatment at a high temperature called a bond strengthening treatment. Furthermore, it is possible to realize an iron-based soft magnetic powder for a dust core that is excellent in thermal stability so that electrical insulation can be maintained well even if strain relief annealing is performed. Moreover, since the phosphoric acid-based chemical conversion film does not contain Co, a high specific resistance can be maintained even if the strain relief annealing is performed at a higher temperature.

また、FeとCoより成る被膜の膜厚は、1〜10nmであることが好ましい。これにより、FeとCoより成る被膜の形成性を維持しつつ鉄基軟磁性粉末の変形の自由度を確保できるため、成形時の前記粉末の密度が上がり高磁束密度を実現できる。より好ましくは、FeとCoより成る被膜の膜厚は、1〜2nm程度である。   Moreover, it is preferable that the film thickness of the film which consists of Fe and Co is 1-10 nm. As a result, the degree of freedom of deformation of the iron-based soft magnetic powder can be secured while maintaining the formability of the film made of Fe and Co, so that the density of the powder at the time of molding can be increased and a high magnetic flux density can be realized. More preferably, the film thickness of the film made of Fe and Co is about 1 to 2 nm.

また、シリコーン樹脂被膜を形成するためのシリコーン樹脂は、三官能性のメチルシリコーン樹脂であることが好ましい。これにより、成形時の前記粉末のハンドリング性が向上する。   Moreover, it is preferable that the silicone resin for forming a silicone resin film is a trifunctional methyl silicone resin. Thereby, the handleability of the powder during molding is improved.

以下に、上記構成に至った理由について詳述する。   Hereinafter, the reason for the above configuration will be described in detail.

本発明者らは、如何にしたら上記従来の圧粉磁心用鉄基軟磁性粉末のような結合強化処理と称する高温での熱処理をせずとも、高密度に成形した場合に、機械的強度に優れ、鉄基軟磁性粉末粒子間を効果的に絶縁することができ、さらに、歪取り焼鈍を行っても電気絶縁性を良好に維持できるような熱的安定性に優れた圧粉磁心用鉄基軟磁性粉末を実現できるのか、鋭意研究を行った。その結果、最重要ポイントとして、以下のようなことがわかった。それは、圧粉磁心用鉄基軟磁性粉末の表面を被覆するためのリン酸系化成被膜用の処理液から添加元素としてのCoを積極的に排除し、むしろその代わりにこのCoを単独で含むリン酸コバルト水溶液を用いて、まず最初に上記粉末の表面に被覆膜を形成することで上記課題を解決できることである。何故、このような構成にすることで、上記課題を解決することができるのかの詳細なメカニズムは、まだ解明されていない。しかし、一つのメカニズムとしては、リン酸コバルト水溶液を用いて形成した膜が、その上に形成されるCoを含まないリン酸系化成被膜の凝集を抑制し、結果としてこのリン酸系化成被膜の破れ(物理的な破壊)を抑制し、機械的強度にも優れ、且つ、電気絶縁性も良好に維持できるのではないかと考えられる。   The present inventors, in any case, have improved mechanical strength when molded at a high density without heat treatment at a high temperature called a bond strengthening treatment such as the conventional iron-based soft magnetic powder for dust cores. Excellent iron core for powder magnetic cores, which can effectively insulate between iron-based soft magnetic powder particles and has excellent thermal stability that can maintain good electrical insulation even after strain relief annealing We conducted intensive research on whether or not a base soft magnetic powder could be realized. As a result, the following points were found as the most important points. It actively excludes Co as an additive element from the treatment solution for phosphate conversion coating for coating the surface of iron-based soft magnetic powder for dust cores, but instead contains this Co alone. The above problem can be solved by first forming a coating film on the surface of the powder using a cobalt phosphate aqueous solution. The detailed mechanism of why such a configuration can solve the above problem has not yet been elucidated. However, as one mechanism, the film formed using the cobalt phosphate aqueous solution suppresses the aggregation of the phosphate conversion coating that does not contain Co formed thereon, and as a result, this phosphate conversion coating It is considered that tearing (physical destruction) is suppressed, mechanical strength is excellent, and electrical insulation can be maintained well.

以下に、本発明を詳細に説明する。   The present invention is described in detail below.

鉄基軟磁性粉末は、強磁性体の金属粉末であり、具体例としては、純鉄粉、鉄基合金粉末(Fe−A1合金、Fe−Si合金、センダスト、パーマロイなど)およびアモルファス粉末等が挙げられる。こうした軟磁性粉末は、例えば、アトマイズ法によって微粒子とした後還元し、その後粉砕すること等によって製造できる。このような製法では、ふるい分け法で評価される粒度分布で累積粒度分布が50%になる粒径が20〜250μm程度の軟磁性粉末が得られるが、本発明においては、平均粒径が50〜150μm程度のものが好ましく用いられる。   The iron-based soft magnetic powder is a ferromagnetic metal powder, and specific examples include pure iron powder, iron-based alloy powder (Fe-A1 alloy, Fe-Si alloy, Sendust, Permalloy, etc.) and amorphous powder. Can be mentioned. Such a soft magnetic powder can be produced, for example, by reducing it into fine particles by the atomizing method, reducing it, and then pulverizing it. In such a production method, a soft magnetic powder having a particle size distribution evaluated by the sieving method and having a cumulative particle size distribution of 50% and a particle size of about 20 to 250 μm is obtained. In the present invention, the average particle size is 50 to 50 μm. Those having a thickness of about 150 μm are preferably used.

本発明においては、上記軟磁性粉末に、まずCoを主成分とする被膜を形成する。このCoを主成分とする被膜は、リン酸コバルト{Co(PO、あるいは、Co(PO・8HO}水溶液を軟磁性粉末に添加して、V型混合機を用いて30分以上混合した後、大気中で30分乾燥することで得られる。この場合のCoの濃度は、軟磁性粉末100質量%中0.005〜0.1質量%である。これにより、Coを主成分とする被膜(最終的には、FeとCoの混合層となる被膜)の膜厚を1nm〜10nmにする。この被膜の膜厚が、1nm未満では歪取り焼鈍温度が450℃以上の場合に、比抵抗を向上させるという十分な効果が得られないばかりか、形成すること自体が難しいためである。また、10nm超とすると硬い殻が出来たようになって、粉末の変形が出来なくなり密度が上がりにくくなるばかりか、被膜自体を厚くすることが難しいためである。好ましくは、1〜2nm程度である。 In the present invention, a coating containing Co as a main component is first formed on the soft magnetic powder. The coating containing Co as a main component is obtained by adding an aqueous solution of cobalt phosphate {Co 3 (PO 4 ) 2 or Co 3 (PO 4 ) 2 · 8H 2 O} to the soft magnetic powder to form a V-type mixer. It is obtained by mixing for 30 minutes or more and then drying in the air for 30 minutes. The Co concentration in this case is 0.005 to 0.1% by mass in 100% by mass of the soft magnetic powder. Thereby, the film thickness of the film containing Co as a main component (finally, the film that becomes a mixed layer of Fe and Co) is set to 1 nm to 10 nm. This is because if the film thickness is less than 1 nm, a sufficient effect of improving the specific resistance cannot be obtained when the strain relief annealing temperature is 450 ° C. or higher, and it is difficult to form the film itself. On the other hand, if the thickness exceeds 10 nm, a hard shell is formed, the powder cannot be deformed and the density is hardly increased, and it is difficult to increase the thickness of the coating itself. Preferably, it is about 1-2 nm.

次に、上記Coを主成分とする被膜が表面に形成された軟磁性粉末に、リン酸系化成被膜を形成する。このリン酸系化成被膜は、オルトリン酸(HPO)を主成分とする処理液による化成処理によって生成するガラス状の被膜である。本発明では、リン酸系化成被膜は、P以外にNa、S、Mg、BおよびWよりなる群から選択される1種以上の元素を含むものでもよい。これらの元素は、2種以上を併用しても構わない。これらの元素の添加量は、軟磁性粉末100質量%中の量として、Pは0.005〜1質量%、Naは0.002〜0.6質量%、Sは0.001〜0.2質量%、Mgは0.001〜0.5質量%、Bは0.001〜0.5質量%、Wは0.0 01〜0.5質量%が好適である。ただし、Coは含まれていない。なお、リン酸系化成被膜の膜厚調整は、軟磁性粉末に対する処理液の比率を調整したり(比率を倍にすれば厚みは倍になる。)、処理液の希釈倍率を調整することで(倍率を半分にすれば膜厚は倍になる。)調整することが出来る。上記リン酸系化成被膜は、所定量に調整された処理液と軟磁性粉末を公知のミキサー、ボールミル、ニーダー、V型混合機、造粒機等で混合し、大気中、減圧下、または真空下で、150〜250℃で乾燥することにより得られる。本発明において非常に重要なポイントは、この後の工程で、上記従来技術のような結合強化処理と称する、非酸化性雰囲気中、500〜1200℃、20〜240分の加熱処理を行う必要がないことである。 Next, a phosphoric acid-based chemical conversion film is formed on the soft magnetic powder on which the film containing Co as a main component is formed. This phosphoric acid-based chemical conversion film is a glassy film formed by chemical conversion treatment with a treatment liquid containing orthophosphoric acid (H 3 PO 4 ) as a main component. In the present invention, the phosphate conversion coating film may contain one or more elements selected from the group consisting of Na, S, Mg, B and W in addition to P. Two or more of these elements may be used in combination. The addition amount of these elements is as follows: P is 0.005 to 1% by mass, Na is 0.002 to 0.6% by mass, and S is 0.001 to 0.2% in 100% by mass of the soft magnetic powder. Mass%, Mg is 0.001 to 0.5 mass%, B is 0.001 to 0.5 mass%, and W is preferably 0.011 to 0.5 mass%. However, Co is not included. In addition, the film thickness adjustment of a phosphoric acid type | system | group chemical conversion film adjusts the ratio of the process liquid with respect to soft-magnetic powder (If a ratio is doubled, thickness will double), or the dilution rate of a process liquid is adjusted. (If the magnification is halved, the film thickness is doubled.) The phosphoric acid-based chemical conversion film is prepared by mixing a treatment liquid adjusted to a predetermined amount and soft magnetic powder using a known mixer, ball mill, kneader, V-type mixer, granulator, etc., and in the atmosphere, under reduced pressure, or vacuum Under drying at 150-250 ° C. In the present invention, a very important point is that in the subsequent step, it is necessary to perform a heat treatment at 500 to 1200 ° C. for 20 to 240 minutes in a non-oxidizing atmosphere referred to as a bond strengthening treatment as in the prior art. It is not.

次に、リン酸系化成被膜で覆われた軟磁性粉末の表面に、さらにシリコーン樹脂被膜を形成する。シリコーン樹脂の架橋・硬化反応終了時(圧粉成形体の成形時)には、粉末同士が強固に結合するので、機械的強度が増大する。また、耐熱性に優れたSi−O結合を形成して熱的安定性に優れた絶縁被膜となる。シリコーン樹脂としては、硬化が遅いものでは粉末がべとついて被膜形成後のハンドリング性が悪いので、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は前記と同じ)を多く持つものが好ましい。しかし、四官能性のQ単位(SiX:Xは前記と同じ)が多く含まれていると、予備硬化の際に粉末同時が強固に結着してしまい、後の成形工程が行えなくなるため好ましくない。よって、T単位が60モル%以上のシリコーン樹脂が好ましく、80モル%以上のシリコーン樹脂がより好ましく、全てT単位であるシリコーン樹脂が最も好ましい。 Next, a silicone resin film is further formed on the surface of the soft magnetic powder covered with the phosphoric acid-based chemical conversion film. At the end of the crosslinking / curing reaction of the silicone resin (at the time of molding the green compact), the powders are firmly bonded to each other, so that the mechanical strength is increased. In addition, an Si—O bond having excellent heat resistance is formed to provide an insulating film having excellent thermal stability. As a silicone resin, since the powder is sticky when the curing is slow and the handling property after film formation is poor, the trifunctionality is higher than the bifunctional D unit (R 2 SiX 2 : X is a hydrolyzable group). It is preferable to have a large number of T units (RSiX 3 : X is the same as described above). However, if a large amount of tetrafunctional Q units (SiX 4 : X is the same as described above) is contained, the powder simultaneously binds strongly at the time of preliminary curing, and the subsequent molding process cannot be performed. It is not preferable. Accordingly, a silicone resin having a T unit of 60 mol% or more is preferable, a silicone resin having 80 mol% or more is more preferable, and a silicone resin having all T units is most preferable.

また、シリコーン樹脂としては、上記Rがメチル基またはフェニル基となっているメチルフェニルシリコーン樹脂が一般的で、フェニル基を多く待つ方が耐熱性は高いとされているが、本発明で意図するような高温の熱処理では、フェニル基の存在は、それほど、有効とは言えなかった。フェニル基の嵩高さが、繊密なガラス状網目構造を乱して、熱的安定性や鉄との化合物形成阻害効果を逆に低減させるのではないかと考えられる。よって、本発明では、メチル基が50モル%以上のメチルフェニルシリコーン樹脂(例えば、信越化学工業社製のKR255、KR311等)を用いることが好ましく、70モル%以上(例えば、信越化学工業社製のKR300等)がより好ましく、フェニル基を全く待たないメチルシリコーン樹脂(例えば、信越化学工業社製のKR251、KR400、KR22OL、KR242A、KR240、KR500、KC89等)が最も好ましい。なお、シリコーン樹脂のメチル基とフェニル基の比率や官能性については、FT−IR等で分析可能である。   Further, as the silicone resin, a methylphenyl silicone resin in which R is a methyl group or a phenyl group is generally used, and it is considered that the heat resistance is higher when waiting for more phenyl groups, but this is intended in the present invention. In such a high temperature heat treatment, the presence of the phenyl group was not so effective. It is thought that the bulkiness of the phenyl group may disturb the delicate glassy network structure and reduce the thermal stability and the compound formation inhibitory effect with iron. Therefore, in the present invention, it is preferable to use a methylphenyl silicone resin having a methyl group of 50 mol% or more (for example, KR255, KR311, etc. manufactured by Shin-Etsu Chemical Co., Ltd.), and 70 mol% or more (for example, manufactured by Shin-Etsu Chemical Co., Ltd. KR300, etc.) are more preferable, and methyl silicone resins that do not wait for phenyl groups at all (for example, KR251, KR400, KR22OL, KR242A, KR240, KR500, KC89, etc., manufactured by Shin-Etsu Chemical Co., Ltd.) are most preferable. In addition, about the ratio and functionality of the methyl group of a silicone resin, and a phenyl group, it can analyze by FT-IR etc.

シリコーン樹脂被膜の付着量は、リン酸系化成被膜が形成された軟磁性粉末とシリコーン樹脂被膜との合計を100質量%としたとき、0.05〜0.3質量%となるように調整することが好ましい。0.05質量%より少ないと、絶縁性に劣り、電気抵抗が低くなるが、0.3質量%より多く加えると、成形体の高密度化が達成しにくい。   The adhesion amount of the silicone resin coating is adjusted to be 0.05 to 0.3% by mass when the total of the soft magnetic powder on which the phosphoric acid-based chemical conversion coating is formed and the silicone resin coating is 100% by mass. It is preferable. If the amount is less than 0.05% by mass, the insulating property is inferior and the electric resistance is lowered. However, if the amount is more than 0.3% by mass, it is difficult to achieve high density of the molded body.

シリコーン樹脂被膜は、アルコール類や、トルエン、キシレン等の石油系有機溶剤等にシリコーン樹脂を溶解させ、この溶液と軟磁性粉末とを混合して有機溶媒を揮発させることにより形成することができる。被膜形成条件は特に限定されるわけではないが、固形分が大体2〜10質量%になるように調製した樹脂溶液を、前記したリン酸系化成被膜が形成された軟磁性粉末100質量部に対し、0.5〜10質量部程度添加して混合し、乾燥すればよい。0.5質量部より少ないと混合に時間がかかったり、被膜が不均一になるおそれがある。一方、10質量部を超えると乾燥に時間がかかったり、乾燥が不充分になるおそれがある。樹脂溶液は適宜加熱しておいても構わない。混合機は前記したものと同様のものが使用可能である。   The silicone resin coating can be formed by dissolving a silicone resin in alcohols, petroleum-based organic solvents such as toluene and xylene, and mixing the solution and soft magnetic powder to volatilize the organic solvent. The film forming conditions are not particularly limited, but the resin solution prepared so that the solid content is about 2 to 10% by mass is added to 100 parts by mass of the soft magnetic powder on which the phosphoric acid-based chemical conversion film is formed. On the other hand, about 0.5 to 10 parts by mass may be added, mixed and dried. If the amount is less than 0.5 parts by mass, mixing may take time or the coating film may become non-uniform. On the other hand, if it exceeds 10 parts by mass, drying may take time or drying may be insufficient. The resin solution may be appropriately heated. The same mixer as described above can be used.

乾燥工程では、用いた有機溶剤が揮発する温度で、かつ、シリコーン樹脂の硬化温度未満に加熱して、有機溶剤を充分に蒸発揮散させることが望ましい。具体的な乾燥温度としては、上記したアルコール類や石油系有機溶剤の場合は、60〜80℃程度が好適である。乾燥後には、凝集ダマを除くために、所定の目開きの篩を通過させておくことが好ましい。   In the drying step, it is desirable to sufficiently evaporate the organic solvent by heating to a temperature at which the organic solvent used volatilizes and below the curing temperature of the silicone resin. A specific drying temperature is preferably about 60 to 80 ° C. in the case of the alcohols and petroleum organic solvents described above. After drying, it is preferable to pass through a sieve having a predetermined opening in order to remove aggregated lumps.

なお、シリコーン樹脂被膜の膜厚調整は、軟磁性粉末に対する樹脂固形分の比率を調整することで(比率を倍にすれば厚みは倍になる。)対応できる。   In addition, the film thickness adjustment of a silicone resin film can respond | correspond by adjusting the ratio of the resin solid content with respect to a soft-magnetic powder (If a ratio is doubled, thickness will double).

次に、上記乾燥後のシリコーン樹脂被膜を予備硬化させることが推奨される。予備硬化とは、シリコーン樹脂被膜の硬化時における軟化過程を粉末状態で終了させる処理である。この予備硬化処理によって、温間成形時(100〜250℃程度)に軟磁性粉末の流れ性を確保することができる。具体的な手法としては、シリコーン樹脂被膜が形成された軟磁性粉末を、この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簡便であるが、薬剤(硬化剤)を用いる手法も利用可能である。予備硬化と、硬化(予備ではない完全硬化)処理との違いは、予備硬化処理では、粉末同士が完全に接着固化することなく、容易に解砕が可能であるのに対し、粉末の成形後に行う高温加熱硬化処理では、樹脂が硬化して粉末同士が接着固化する点である。完全硬化処理によって成形体強度が向上する。   Next, it is recommended to pre-cure the dried silicone resin film. The pre-curing is a process for terminating the softening process at the time of curing the silicone resin film in a powder state. By this pre-curing treatment, the flowability of the soft magnetic powder can be ensured during warm forming (about 100 to 250 ° C.). As a specific method, a method of heating a soft magnetic powder having a silicone resin coating formed in the vicinity of the curing temperature of the silicone resin for a short time is simple, but a method using a drug (curing agent) can also be used. is there. The difference between pre-curing and curing (complete curing that is not preliminary) is that the pre-curing process can be easily crushed without completely solidifying the powder, whereas In the high temperature heat curing process to be performed, the resin is cured and the powders are bonded and solidified. The strength of the molded body is improved by the complete curing treatment.

上記したように、シリコーン樹脂を予備硬化させた後、解砕することで、流動性に優れた粉末が得られ、圧粉成形の際に成形型へ、砂のようにさらさらと投入することができるようになる。予備硬化させないと、例えば温間成形の際に粉末同士が付着して、成型型への短時間での投入が困難となることがある。実操業上、ハンドリング性の向上は非常に有
意義である。また、予備硬化させることによって、得られる圧粉磁心の比抵抗が非常に向上することが見出されている。この理由は明確ではないが、硬化の際の軟磁性粉末との密着性が上がるためではないかと考えられる。
As mentioned above, after pre-curing the silicone resin, it can be crushed to obtain a powder with excellent fluidity, which can be poured into the mold during sand compaction like sand. become able to. If it is not pre-cured, for example, powders may adhere to each other during warm molding, and it may be difficult to charge the mold in a short time. In practical operation, the improvement of handling is very significant. It has also been found that the specific resistance of the resulting dust core is greatly improved by pre-curing. The reason for this is not clear, but it is thought that this is because the adhesiveness with the soft magnetic powder during curing increases.

短時間加熱法によって予備硬化を行う場合、100〜200℃で5〜100分の加熱処理を行うとよい。130〜170℃で10〜30分がより好ましい。予備硬化後も、前述したように、篩を通過させておくことが好ましい。   When pre-curing is performed by a short-time heating method, the heat treatment is preferably performed at 100 to 200 ° C. for 5 to 100 minutes. 10-30 minutes is more preferable at 130-170 degreeC. Even after the preliminary curing, as described above, it is preferable to pass through a sieve.

本発明の圧粉磁心用鉄基軟磁性粉末には、さらに潤滑剤が含有されたものであってもよい。この潤滑剤の作用により、圧粉磁心用粉末を圧縮成形する際の軟磁性粉末間、あるいは軟磁性粉末と成形型内壁間の摩擦抵抗を低減でき、成形体の型かじりや成形時の発熱を防止することができる。このような効果を有効に発揮させるためには、潤滑剤が粉末全量
中、0.2質量%以上含有されていることが好ましい。しかし、潤滑剤量が多くなると、圧粉体の高密度化に反するため、0.8質量%以下にとどめることが好ましい。また、圧縮成形する際に、成形型内壁面に潤滑剤を塗布した後、成形するような場合(型潤滑成形)には、0.2質量%より少ない潤滑剤量でも構わない。
The iron-based soft magnetic powder for dust core of the present invention may further contain a lubricant. The action of this lubricant can reduce the frictional resistance between the soft magnetic powder during compression molding of the powder for the powder magnetic core, or between the soft magnetic powder and the inner wall of the molding die, and it can reduce the mold galling and heat generation during molding. Can be prevented. In order to effectively exhibit such an effect, it is preferable that the lubricant is contained in an amount of 0.2% by mass or more in the total amount of the powder. However, if the amount of lubricant increases, it is against the densification of the green compact, so it is preferable to keep it at 0.8% by mass or less. Further, when compression molding is performed, a lubricant is applied to the inner wall surface of the mold and then molded (mold lubrication molding), and the amount of lubricant may be less than 0.2% by mass.

潤滑剤としては、従来から公知のものを使用すればよく、具体的には、ステアリン酸亜鉛、ステアリン酸リチウム、ステアリン酸カルシウムなどのステアリン酸の金属塩粉末、およびパラフィン、ワックス、天然または合成樹脂誘導体等が挙げられる。   As the lubricant, conventionally known ones may be used. Specifically, metal stearate powder such as zinc stearate, lithium stearate, calcium stearate, and paraffin, wax, natural or synthetic resin derivatives. Etc.

本発明の圧粉磁心用鉄基軟磁性粉末は、モータやトランス用のような例えば周波数が50kHz程度以下で使用するコア材(圧粉磁心)の製造のために用いられるものである。この圧粉磁心を製造するには、まず、上記粉末を圧縮成形する。圧縮成形法は特に限定されず、従来公知の方法が採用可能である。   The iron-based soft magnetic powder for dust core of the present invention is used for the production of a core material (dust core) used at a frequency of about 50 kHz or less, such as for motors and transformers. In order to manufacture this powder magnetic core, first, the powder is compression molded. The compression molding method is not particularly limited, and a conventionally known method can be employed.

圧縮成形の好適条件は、面圧で、490MPa〜1960MPa、より好ましくは790MPa〜1180MPaである。特に、980MPa以上の条件で圧縮成形を行うと、密度が7.50g/cm以上である圧粉磁心を得やすく、高強度で磁気特性(磁束密度)の良好な圧粉磁心が得られるため好ましい。成形温度は、室温成形、温間成形(100〜250℃)いずれも可能である。型潤滑成形で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。 A suitable condition for compression molding is a surface pressure of 490 MPa to 1960 MPa, more preferably 790 MPa to 1180 MPa. In particular, when compression molding is performed under conditions of 980 MPa or more, a dust core having a density of 7.50 g / cm 3 or more can be easily obtained, and a dust core having high strength and good magnetic properties (magnetic flux density) can be obtained. preferable. The molding temperature can be either room temperature molding or warm molding (100 to 250 ° C.). It is preferable to perform warm molding by mold lubrication molding because a high-strength powder magnetic core can be obtained.

成形後は、圧粉磁心のヒステリシス損を低減するため高温で熱処理する。このときの熱処理温度は400℃以上が好ましく、比抵抗の劣化がなければ、より高温で熱処理することが望ましい(具体的には、500℃〜600℃が好ましい。)。また、その熱処理雰囲気は酸素を含まなければ特に限定されないが、窒素等の不活性ガス雰囲気下が好ましい。熱処理時間は比抵抗の劣化がなければ特に限定されないが、20分以上が好ましく、30分以上がより好ましい。   After molding, heat treatment is performed at a high temperature to reduce the hysteresis loss of the dust core. The heat treatment temperature at this time is preferably 400 ° C. or higher, and it is desirable to perform the heat treatment at a higher temperature (specifically, 500 ° C. to 600 ° C. is preferable) if there is no deterioration in specific resistance. The heat treatment atmosphere is not particularly limited as long as it does not contain oxygen, but is preferably an inert gas atmosphere such as nitrogen. The heat treatment time is not particularly limited as long as the specific resistance does not deteriorate, but is preferably 20 minutes or more, and more preferably 30 minutes or more.

以下、実施例に基づいて本発明を詳細に述べる。ただし、下記実施例は本発明を制限するものではなく、前・後記の趣旨を逸脱しない範囲で変更実施をすることは全て本発明の技術的範囲に包含される。なお、特に断らない限り、「部」は「質量部」を、「%」は「質量%」をそれぞれ意味する。   Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

(鉄基軟磁性粉末を1番目に被覆する被膜(FeとCoより成る被膜)の効果)
鉄基軟磁性粉末として純鉄粉(神戸製鋼所製;アトメル300NH;平均粒径80〜100μm)を用い、まずCoを主成分とする被膜を形成した。具体的には、水:1000部、Co(PO30部を混合して、更に10倍に希釈した処理液200gを、目開き300μmの篩を通した純鉄粉1000gに添加して、V型混合機を用いて30分以上混合した後、大気中で30分乾燥し、目開き300μmの篩を通した。この条件で形成した被膜は、FeとCoより成り、その被膜の膜厚は7nmであった。
(Effect of the first coating of iron-based soft magnetic powder (coating composed of Fe and Co))
A pure iron powder (manufactured by Kobe Steel; Atmel 300NH; average particle size of 80 to 100 μm) was used as the iron-based soft magnetic powder, and a coating containing Co as a main component was first formed. Specifically, water: 1000 parts, by mixing Co 3 (PO 4) 2 30 parts, further treatment liquid 200g diluted 10-fold, was added to the pure iron powder 1000g through a sieve having a mesh opening 300μm Then, after mixing for 30 minutes or more using a V-type mixer, it was dried in the air for 30 minutes and passed through a sieve having an opening of 300 μm. The film formed under these conditions was composed of Fe and Co, and the film thickness was 7 nm.

次に、上記Coを主成分とする被膜が表面に形成された純鉄粉に、リン酸系化成被膜(但し、Coは含まれていない)を形成した。リン酸系化成被膜形成のための処理液(10倍希釈前の原液)組成は、以下の通りとした(また、これにより形成されるリン酸系化成被膜中の添加元素を表1のNo.1〜25に示した)。ただし、この場合のリンの濃度は、純鉄粉100質量%中0.07質量%となるようにした。また、比較のために、上記Coを主成分とする被膜が予め表面に形成されていない純鉄粉に、直接Coが添加されたリン酸系化成被膜を形成するための処理液(10倍希釈前の原液)組成も合わせて下記に示す(また、これにより形成されるリン酸系化成被膜中の添加元素を表2のNo.26〜50に示した)。   Next, a phosphoric acid-based chemical conversion film (however, Co is not included) was formed on the pure iron powder on which the film containing Co as a main component was formed. The composition of the treatment liquid for forming the phosphoric acid-based chemical conversion film (stock solution before 10-fold dilution) was as follows (in addition, the additive elements in the phosphoric acid-based chemical conversion film formed thereby were designated as No. 1 in Table 1). 1-25). However, the phosphorus concentration in this case was 0.07% by mass in 100% by mass of pure iron powder. For comparison, a treatment liquid (diluted 10 times) for forming a phosphoric acid-based chemical conversion film in which Co is directly added to pure iron powder on which the Co-based film is not formed on the surface in advance. The composition of the previous stock solution is also shown below (and the additive elements in the phosphoric acid-based chemical conversion film formed thereby are shown in Nos. 26 to 50 in Table 2).

No.1〜5で用いた処理液…水:1000部、HPO:193部
No.6〜10で用いた処理液…水:1000部、HPO:193部、MgO:31部、HBO:30部
No.11〜15で用いた処理液…水:1000部、HPO:193部、MgO:31部、HBO:30部、HPWl240・nH0:150部
No.16〜20で用いた処理液…水:1000部、HPO:193部、MgO:31部、HBO:30部、SiO・12WO・26H0:150部
No.21〜25で用いた処理液…水:1000部、NaHPO:88.5部、HPO:181部、HSO:61部
No.26〜30で用いた処理液…水:1000部、HPO:193部、Co(PO:30部
No.31〜35で用いた処理液…水:1000部、HPO:193部、MgO:31部、HBO:30部、Co(PO:30部
No.36〜40で用いた処理液…水:1000部、HPO:193部、MgO:31部、HBO:30部、HPWl240・nH0:150部、Co(PO:30部
No.41〜45で用いた処理液…水:1000部、HPO:193部、MgO:31部、HBO:30部、SiO・12WO・26H0:150部、Co(PO:30部
No.46〜50で用いた処理液…水:1000部、NaHPO:88.5部、HPO:181部、HSO:61部、Co(PO:30部
No. Treatment liquid used in 1 to 5: water: 1000 parts, H 3 PO 4 : 193 parts Treatment liquid used in 6 to 10: water: 1000 parts, H 3 PO 4 : 193 parts, MgO: 31 parts, H 3 BO 3 : 30 parts Treatment liquid used in 11-15 ... water: 1000 parts, H 3 PO 4: 193 parts, MgO: 31 parts, H 3 BO 3: 30 parts, H 3 PW l2 O 40 · nH 2 0: 150 parts No. Treatment liquid used in 16 to 20: water: 1000 parts, H 3 PO 4 : 193 parts, MgO: 31 parts, H 3 BO 3 : 30 parts, SiO 2 · 12WO 3 · 26H 2 0: 150 parts Treatment liquid used in 21 to 25: water: 1000 parts, Na 2 HPO 4 : 88.5 parts, H 3 PO 4 : 181 parts, H 2 SO 4 : 61 parts Treatment liquid used in Nos. 26 to 30: Water: 1000 parts, H 3 PO 4 : 193 parts, Co 3 (PO 4 ) 2 : 30 parts Treatment liquid used in 31 to 35: water: 1000 parts, H 3 PO 4 : 193 parts, MgO: 31 parts, H 3 BO 3 : 30 parts, Co 3 (PO 4 ) 2 : 30 parts Treatment liquid used in 36 to 40 ... water: 1000 parts, H 3 PO 4: 193 parts, MgO: 31 parts, H 3 BO 3: 30 parts, H 3 PW l2 O 40 · nH 2 0: 150 parts, Co 3 (PO 4) 2: 30 parts No. Treatment liquid used in 41 to 45: water: 1000 parts, H 3 PO 4 : 193 parts, MgO: 31 parts, H 3 BO 3 : 30 parts, SiO 2 · 12WO 3 · 26H 2 0: 150 parts, Co 3 (PO 4) 2: 30 parts No. Treatment liquid used in 46 to 50: Water: 1000 parts, Na 2 HPO 4 : 88.5 parts, H 3 PO 4 : 181 parts, H 2 SO 4 : 61 parts, Co 3 (PO 4 ) 2 : 30 parts

Figure 0004856602
Figure 0004856602

Figure 0004856602
Figure 0004856602

次に、信越化学工業社製のシリコーン樹脂「KR220L」をトルエンに溶解後、4.8%の固形分濃度の樹脂溶液を作製した。その樹脂溶液を上記リン酸系化成被膜が施された上記試料No.1〜50の各純鉄粉に対して樹脂固形分が0.1質量%になるように添加混合した。これをオーブン炉で大気中、75℃、30分間加熱し、乾燥してシリコーン樹脂被膜を形成した後、所定の目開きの篩を通した。   Next, a silicone resin “KR220L” manufactured by Shin-Etsu Chemical Co., Ltd. was dissolved in toluene to prepare a resin solution having a solid content concentration of 4.8%. The resin solution was mixed with the above-mentioned sample no. It added and mixed so that resin solid content might be 0.1 mass% with respect to each 1-50 pure iron powder. This was heated in an oven furnace at 75 ° C. for 30 minutes in the atmosphere, dried to form a silicone resin film, and then passed through a sieve with a predetermined opening.

続いて、上記シリコーン樹脂被膜が施された上記試料No.1〜50の各純鉄粉を150℃で30分間、大気中で予備硬化処理を行った。その後に下記のような金型を用いた圧粉成形を行った。   Subsequently, the sample No. 1 was coated with the silicone resin film. Each 1-50 pure iron powder was pre-cured in air at 150 ° C. for 30 minutes. Thereafter, compacting using a mold as described below was performed.

次に、ステアリン酸亜鉛をアルコールに分散させて金型表面に塗布した後、上記予備硬化処理を終えた上記試料No.1〜50の各純鉄粉をそれぞれ上記金型内に入れ、室温下で面圧980MPaでプレス成形した。このプレス成形後のトロイダル形状の圧粉成形体の寸法は、外径φ45mm×内径φ33mm×高さ5mmであり、密度は7.5g/cmである。その後、これらの圧粉成形体を窒素雰囲気下で、400℃〜600℃で、30分間保持しその後、炉冷する熱処理(焼鈍)を行った。昇温速度は約5℃/分とした。このようにして得られたトロイダル形状の圧粉成形体(それぞれ上記試料No.1〜50に対応する)の比抵抗を4端子法で測定した(測定結果は、それぞれ表1、表2に示した)。 Next, after the zinc stearate was dispersed in alcohol and applied to the surface of the mold, the pre-curing treatment was completed. 1 to 50 pure iron powders were placed in the above molds and press molded at room temperature at a surface pressure of 980 MPa. The dimensions of the pressed toroidal compact after the press molding are outer diameter φ45 mm × inner diameter φ33 mm × height 5 mm, and the density is 7.5 g / cm 3 . Then, these compacting bodies were heat-processed (annealing) which hold | maintained at 400 degreeC-600 degreeC for 30 minutes in nitrogen atmosphere, and was furnace-cooled after that. The heating rate was about 5 ° C./min. The specific resistances of the toroidal shaped compacts thus obtained (corresponding to the above sample Nos. 1 to 50) were measured by the four-terminal method (measurement results are shown in Tables 1 and 2, respectively). )

例えば、50kHz程度以下で使用するモータやトランス用のコア材(圧粉磁心)にあっては、低鉄損と高磁束密度の両方を実現することが求められている。それには、まず高磁束密度を満足させるために高密度に成形し、その場合にも機械的強度に優れ、純鉄粉末粒子間が効果的に絶縁されることが必要である。また、低鉄損にするためにはヒステリシス損を低減しなければならない。この目的で歪取り焼鈍が行われる(より高温で歪取り焼鈍を行う程、ヒステリシス損の低減効果は大きい)が、この熱処理を受けても電気絶縁性を良好に維持できるような熱的安定性に優れた(高温の熱処理を受けても比抵抗の低下が抑制される)圧粉磁心用純鉄粉末が必要である。何故ならば、比抵抗の低下が著しいと、例えば50kHz程度で使用した場合の渦電流損が非常に大きくなり、低鉄損を実現できなくなるからである。これは、結果としてモータやトランスの性能を低下させることにつながる。このように、より高温で行う歪取り焼鈍後の比抵抗の低下を抑制することが極めて重要である。このような視点で、表1、表2に示された比抵抗の測定結果を考察する。   For example, a core material (a powder magnetic core) for a motor or transformer used at about 50 kHz or less is required to realize both a low iron loss and a high magnetic flux density. For this purpose, it is first necessary to form a high density in order to satisfy a high magnetic flux density, in which case the mechanical strength is also excellent, and the pure iron powder particles must be effectively insulated. In order to reduce the iron loss, the hysteresis loss must be reduced. For this purpose, stress relief annealing is performed (the higher the stress relief annealing, the greater the effect of reducing hysteresis loss), but the thermal stability is such that electrical insulation can be maintained well even after this heat treatment. Therefore, there is a need for a pure iron powder for a dust core that is excellent in resistance (a decrease in resistivity is suppressed even when subjected to high-temperature heat treatment). This is because, if the specific resistance is remarkably lowered, for example, eddy current loss becomes extremely large when used at about 50 kHz, and low iron loss cannot be realized. This results in a decrease in the performance of the motor and transformer. As described above, it is extremely important to suppress a decrease in specific resistance after the stress relief annealing performed at a higher temperature. From such a viewpoint, the measurement results of the specific resistance shown in Tables 1 and 2 will be considered.

例えば、表1の実施例(試料No.1〜5;リン酸系化成被膜中に添加元素としてCoがない。ただし、下層の被膜中にCoがある。)と表2の比較例(試料No.26〜30;リン酸系化成被膜中に添加元素としてCoがある。ただし、下層の被膜自体がない。)の比抵抗をそれぞれ比較してみると、いずれの熱処理温度(歪取り焼鈍の温度)においても実施例の方が比抵抗が高い。また、その効果は熱処理温度が高い程、顕著である。この傾向は、他の実施例(試料No.6〜10、No.11〜15、No.16〜20、No.21〜25)と比較例(試料No.31〜35、No.36〜40、No.41〜45、No.46〜50)とをそれぞれ対比した結果においても同様である。また、実施例(試料No.21〜25)は、全実施例の中で比抵抗が相対的に高い。特に、熱処理温度が600℃における比抵抗の高さが目立つ。   For example, the examples in Table 1 (Sample Nos. 1 to 5; Co is not added as an additive element in the phosphoric acid-based chemical conversion coating. However, Co is present in the lower layer coating) and the comparative examples in Table 2 (Sample No. .26-30: Co as an additive element in the phosphoric acid-based chemical conversion coating film, but there is no lower layer coating itself. ) Also has a higher specific resistance. Moreover, the effect becomes more remarkable as the heat treatment temperature is higher. This tendency is similar to other examples (samples Nos. 6 to 10, Nos. 11 to 15, Nos. 16 to 20, Nos. 21 to 25) and comparative examples (samples Nos. 31 to 35, Nos. 36 to 40). , No. 41 to 45, No. 46 to 50), and the same result. Moreover, an Example (sample No. 21-25) has a relatively high specific resistance in all the Examples. In particular, the specific resistance is high when the heat treatment temperature is 600 ° C.

なお、リン酸系化成被膜中には、不可避的にCoを多少含むことも考えられるが、望ましくはCoを含まない方が良い。これにより、歪取り焼鈍をより高温で行っても、高い比抵抗を維持できる。   The phosphoric acid-based chemical conversion film may inevitably contain some Co, but it is desirable that it does not contain Co. Thereby, a high specific resistance can be maintained even if the strain relief annealing is performed at a higher temperature.

これらの結果は、Coをリン酸系化成被膜中の添加元素から抜き、その下の被膜を構成するための処理液の中に単独元素として別途加える方が、高温熱処理(歪取り焼鈍)後の比抵抗の低下を抑制できることを示している。また、これらの効果を生み出すために、従来例のような純鉄粉の表面を被覆する一層目の被膜と二層目の被膜の形成後に結合強化処理と称する高温での熱処理を別途付加することが必要なくなることが何よりも大きなメリットである。   These results show that after removing Co from the additive element in the phosphoric acid-based chemical conversion film and adding it separately as a single element in the treatment liquid for forming the coating underneath it, after high-temperature heat treatment (strain relief annealing) It shows that a decrease in specific resistance can be suppressed. In order to produce these effects, a heat treatment at a high temperature called a bond strengthening treatment is additionally applied after the formation of the first layer coating and the second layer coating on the surface of pure iron powder as in the conventional example. The biggest advantage is that it is no longer necessary.

Claims (4)

鉄基(但し、Fe−Co系合金、Fe−Ni−Co系合金を除く)軟磁性粉末表面に、FeとCoより成る被膜と、Coを含まないリン酸系化成被膜と、シリコーン樹脂被膜とが、この順に形成されていることを特徴とする圧粉磁心用鉄基軟磁性粉末。 An iron-based (excluding Fe-Co alloy and Fe-Ni-Co alloy) soft magnetic powder surface, a coating made of Fe and Co, a phosphate-based chemical conversion coating not containing Co , a silicone resin coating, Are formed in this order, an iron-based soft magnetic powder for a dust core. 前記FeとCoより成る被膜の膜厚は、1〜10nmであることを特徴とする請求項1に記載の圧粉磁心用鉄基軟磁性粉末。 The iron-based soft magnetic powder for a dust core according to claim 1, wherein the film made of Fe and Co has a thickness of 1 to 10 nm. 前記シリコーン樹脂被膜を形成するためのシリコーン樹脂は、三官能性のメチルシリコーン樹脂であることを特徴とする請求項1または2に記載の圧粉磁心用鉄基軟磁性粉末。 Silicone resins for forming the silicone resin coating film, trifunctional dust core for iron-based soft magnetic powder according to claim 1 or 2, characterized in that the methyl silicone resin. 請求項1乃至のいずれかに記載の圧粉磁心用鉄基軟磁性粉末を成形して得られた圧粉磁心。 A dust core obtained by molding the iron-based soft magnetic powder for dust core according to any one of claims 1 to 3 .
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