JP2010123699A - High-magnetic-flux-density dust core - Google Patents
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Abstract
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本発明は、鉄元素を含んだ磁性粉を圧縮成形することにより製造される圧分磁心に係り、特に回転電機，リアクトルなどの電機部品に用いるに好適な圧粉磁心に関する。 The present invention relates to a magnetically divided magnetic core manufactured by compression molding magnetic powder containing an iron element, and more particularly to a powder magnetic core suitable for use in electric parts such as a rotating electric machine and a reactor.
近年、環境問題の観点から、電気自動車が注目されている。電気自動車は、動力源として回転電機を、またインバータ回路出力には平滑トランスを備えており、これら部品の効率向上が求められている。これに用いる磁心は低鉄損で、かつ、高磁束密度であることは勿論のこと、それらの磁気特性が低周波から高周波の領域においても低下しないことが求められている。 In recent years, electric vehicles have attracted attention from the viewpoint of environmental problems. An electric vehicle is provided with a rotating electrical machine as a power source and a smoothing transformer at an inverter circuit output, and improvement in the efficiency of these parts is required. The magnetic core used for this has a low iron loss and a high magnetic flux density, and it is required that their magnetic properties do not deteriorate even in the low to high frequency region.
鉄損には、磁心の比抵抗と関係の大きい渦電流損と、鉄粉の製造の過程およびその後のプロセス履歴から生じる鉄粉内の歪に影響を受けるヒステリシス損とがある。そして、鉄損（Ｗ）は下記（式１）のように渦電流損（Ｗｅ）とヒステリシス損（Ｗｈ）の和で示すことができる。（式１）中、ｆは周波数、Ｂｍは励磁磁束密度、ρは比抵抗、ｔは材料の厚さ、ｋ1とｋ2は係数である。 The iron loss includes an eddy current loss that has a large relationship with the specific resistance of the magnetic core, and a hysteresis loss that is affected by the distortion in the iron powder resulting from the process of manufacturing the iron powder and the subsequent process history. The iron loss (W) can be represented by the sum of eddy current loss (We) and hysteresis loss (Wh) as shown below (Formula 1). In (Expression 1), f is a frequency, Bm is an exciting magnetic flux density, ρ is a specific resistance, t is a thickness of the material, and k 1 and k 2 are coefficients.
Ｗ＝Ｗｅ＋Ｗｈ＝（ｋ1Ｂｍ2ｔ2／ρ）ｆ2＋ｋ2Ｂｍ1.6ｆ ・・・（式１） W = We + Wh = (k 1 Bm 2 t 2 / ρ) f 2 + k 2 Bm 1.6 f (Formula 1)
（式１）から、渦電流損（Ｗｅ）は周波数ｆの二乗に比例して大きくなるので、特に、高周波での磁気特性を低下させないためには、その渦電流損（Ｗｅ）の抑制が不可欠である。圧粉磁心の渦電流の発生を抑えるためには、用いる磁粉のサイズを最適化し、かつ、磁粉一つ一つの表面に絶縁膜を形成させ、その磁粉を用い圧縮成形した圧粉磁心を用いる必要がある。 From (Equation 1), since the eddy current loss (We) increases in proportion to the square of the frequency f, it is indispensable to suppress the eddy current loss (We) particularly in order not to deteriorate the magnetic characteristics at high frequencies. It is. In order to suppress the generation of eddy currents in the dust core, it is necessary to optimize the size of the magnet powder to be used, and to use a dust core that has been compression-molded with the insulation film formed on the surface of each magnet powder. There is.
このような圧粉磁心において、絶縁が不十分であると比抵抗ρが低下して、渦電流損（Ｗｅ）が大きくなる。一方、絶縁性を高めるために絶縁被膜を厚くすると、磁心中の軟磁性粉の占める容積の割合が低下し、磁束密度が低下する。また、磁束密度を向上させるために、軟磁性粉の圧縮成形を高圧で行って、軟磁性粉の密度を増加させると、成形時の軟磁性粉の歪が避けられず、ヒステリシス損（Ｗｈ）が大きくなるため、結果として鉄損（Ｗ）の抑制は難しい。特に、低周波領域においては渦電流損（Ｗｅ）が小さいため、鉄損（Ｗ）中のヒステリシス損（Ｗｈ）の影響が大きくなる。 In such a dust core, if the insulation is insufficient, the specific resistance ρ is reduced, and the eddy current loss (We) is increased. On the other hand, when the insulating film is thickened to improve the insulation, the volume ratio of the soft magnetic powder in the magnetic core is reduced, and the magnetic flux density is reduced. Also, in order to improve the magnetic flux density, if the density of the soft magnetic powder is increased by compressing the soft magnetic powder at a high pressure, the distortion of the soft magnetic powder during molding cannot be avoided, and the hysteresis loss (Wh) As a result, it is difficult to suppress iron loss (W). In particular, since the eddy current loss (We) is small in the low frequency region, the influence of the hysteresis loss (Wh) in the iron loss (W) becomes large.
このような課題に対しこれまで鉄又は鉄を主成分とする合金粉末（以降鉄粉とする）の表面にフッ化物絶縁コートを施すことで、粒子間の絶縁を確保し、磁心全体の比抵抗を増加させることでマクロな渦電流損失を低下させる手法が提示されてきた。特許文献１には、フッ化物絶縁コートが、高温での成形体熱処理を行っても比抵抗低下が少ないことが開示されている。 Until now, the surface of iron or iron-based alloy powder (hereinafter referred to as iron powder) is coated with a fluoride insulation coating to ensure insulation between particles and the specific resistance of the entire magnetic core. A technique has been proposed to reduce macro eddy current loss by increasing. Patent Document 1 discloses that the fluoride insulation coat does not cause a decrease in specific resistance even when the compact is heat treated at a high temperature.
絶縁コート膜としてのフッ化物自体は融点が１０００℃以上であり、５００〜６００℃で分解するリン酸塩と異なり、高温において高抵抗である。しかし、温度上昇に伴い比抵抗は、低下割合は小さいものの減少する。また圧縮に伴い同様に比抵抗低下することから、絶縁膜破壊など、欠陥部を通じた伝導現象が懸念されている。 Fluoride itself as an insulating coating film has a melting point of 1000 ° C. or higher, and has a high resistance at high temperatures, unlike phosphates that decompose at 500 to 600 ° C. However, as the temperature rises, the specific resistance decreases although the rate of decrease is small. In addition, since the specific resistance similarly decreases with compression, there is a concern about conduction phenomena through defective portions such as insulation film breakdown.
本発明の圧粉磁心は、鉄又は鉄を主成分とする合金の粉末の表面に、フッ化物を含有する絶縁層を形成したものを圧縮して成形した圧粉磁心において、絶縁層が、フッ化物と鱗片状の鉄酸化物とを有することを特徴とする。より具体的には、絶縁層に主に粒状のフッ化物と鉄酸化物からなる剥離体とが混在していることを特徴とする。 The dust core of the present invention is a dust core formed by compressing and forming a surface of a powder of iron or an alloy containing iron as a main component and forming an insulating layer containing fluoride. It is characterized by having a compound and scaly iron oxide. More specifically, the insulating layer is characterized by a mixture of mainly granular fluoride and a peeled body made of iron oxide.
また、鉄酸化物は主にマグネタイト又はフェライト或いはそれらの混合物であり、鉄酸化物の一部に金属鉄を含むことを特徴とする。 The iron oxide is mainly magnetite, ferrite, or a mixture thereof, and is characterized in that metallic iron is included in a part of the iron oxide.
さらに、フッ化物がフッ化マグネシウムであることを特徴とする。 Furthermore, the fluoride is magnesium fluoride.
また、剥離体が、鱗片状又は繊維状であることを特徴とし、鉄酸化物の長辺長さがフッ化物の平均粒径長さの２倍以上あることを特徴とする。 Further, the peeled body is characterized by a scale shape or a fiber shape, and the long side length of the iron oxide is at least twice the average particle size length of the fluoride.
次に、本発明の圧粉磁心製造方法は、鉄又は鉄を主成分とする合金の粉末の表面に、フッ化物を含有する絶縁層を形成したものを圧縮して成形する圧粉磁心製造方法であって、絶縁層を形成する際に、鉄又は鉄を主成分とする合金の粉末に一定の圧力を与えながら処理液を塗布及び乾燥させることを特徴とする。 Next, the method for producing a dust core according to the present invention is a method for producing a dust core in which an insulating layer containing fluoride is formed on the surface of iron or a powder of an alloy containing iron as a main component. In forming the insulating layer, the treatment liquid is applied and dried while applying a certain pressure to the powder of iron or an alloy containing iron as a main component.
また、圧力が前記鉄又は鉄を主成分とする合金の粉末表面の自然酸化膜を剥離させる以上の強さであることを特徴とする。 In addition, the pressure is more than the strength of peeling the natural oxide film on the powder surface of the iron or an alloy containing iron as a main component.
さらに、塗布液に、鱗片状の鉄酸化物粉または鉄薄片を混合させ、鉄表面に塗布及び乾燥させて定着させることを特徴とする。 Further, the present invention is characterized in that scaly iron oxide powder or iron flakes are mixed in the coating solution, and applied and dried on the iron surface to be fixed.
本発明は、高密度かつ高抵抗で、磁気特性に優れた圧粉磁心を提供するものである。 The present invention provides a dust core having high density and high resistance and excellent magnetic properties.
本発明者らの継続検討の結果、フッ化物絶縁圧粉磁心比抵抗には成形圧依存があり、たとえば高磁束密度の実現のため、成形圧を増加させると比抵抗が低下し、結果として渦電流損失増大を招くことがわかった。具体的には、平均圧力１ＧＰａでは０.１ｍΩ・ｍ以上あった比抵抗が、成形圧１.５ＧＰａでは０.０４ｍΩ・ｍと低下してしまうのである。このため、１.５ＧＰａで成形した試料は渦電流損失が２倍に増大した。 As a result of continuous studies by the present inventors, the specific resistance of the fluoride insulating powder magnetic core depends on the molding pressure. For example, in order to achieve a high magnetic flux density, when the molding pressure is increased, the specific resistance decreases, resulting in a vortex It was found that current loss increased. Specifically, the specific resistance of 0.1 mΩ · m or more at an average pressure of 1 GPa decreases to 0.04 mΩ · m at a molding pressure of 1.5 GPa. For this reason, the sample molded at 1.5 GPa has doubled the eddy current loss.
以下、本発明の実施例に基づき詳細に説明する。 Hereinafter, it demonstrates in detail based on the Example of this invention.
（実施例１）
本発明において、フッ化物は、アルコールをベースとしフッ化マグネシウムゲルを分散させた処理液を当初ビーカ中で、薬さじを用い解砕しながら添加及び乾燥させて塗布していた。ＭｇＦ2塗布の場合、Ｍｇ原料はＭｇ（ＣＨ3ＣＯＯ）2・４Ｈ2Ｏを用いて処理液を作製した。これらの処理を、以下に示す。
Example 1
In the present invention, the fluoride was applied by adding and drying a treatment solution in which magnesium fluoride gel was dispersed based on alcohol in an initial beaker while crushing using a spoon. In the case of applying MgF 2, a treatment liquid was prepared using Mg (CH 3 COO) 2 .4H 2 O as the Mg raw material. These processes are shown below.
［試料形成］
（１）原料鉄粉１００ｇに対して２０mLのＭｇＦ2処理液を用意した。
（２）ロータリエバポレータを用いて、容量１Ｌのフラスコに、膜厚１５０nm相当となるＭｇＦ2処理液と、ガスアトマイズ鉄粉１００ｇと直径５mmのガラスビーズ１００ｇを投入し、１００Ｐａまで減圧して毎分１４０回転で回転させて１.５ｈ乾燥処理を行った。
（３）（２）の溶媒の除去を行った鉄粉を石英製ボートに移し、５×１０-5torrの減圧下で２００℃、３０分と３５０℃、３０分の熱処理を行って原料鉄粉を作製した。
（４）さらにこの処理鉄粉に減圧下で６００℃、６０分の予備熱処理を行った。
（５）（４）で熱処理した鉄粉を、超硬型を用い外径２５mm内径１５mmのリング試料を圧縮により形成した。厚さは４mmで本試料は磁束密度と保磁力の磁気測定用である。
（６）（５）で形成した鉄粉を直径１１.３mmの円柱型を用い、圧縮により厚さ２mmの円柱試料を作製した。成形圧力は１.０〜１.５ＧＰａとした。本試料は比抵抗値測定用である。
（７）（６）で形成した試料を６００℃で５×１０-5torrの減圧下で熱処理を施した。
[Sample formation]
(1) A 20 mL MgF 2 treatment solution was prepared for 100 g of raw iron powder.
(2) Using a rotary evaporator, put a MgF 2 treatment solution with a film thickness of 150 nm, 100 g of gas atomized iron powder and 100 g of glass beads with a diameter of 5 mm into a 1 L flask, and reduce the pressure to 100 Pa to 140 per minute. The mixture was rotated for 1.5 hours and dried for 1.5 hours.
(3) The iron powder from which the solvent of (2) has been removed is transferred to a quartz boat and subjected to heat treatment at 200 ° C., 30 minutes and 350 ° C. for 30 minutes under a reduced pressure of 5 × 10 −5 torr, and the raw material iron Powder was prepared.
(4) Further, this treated iron powder was preliminarily heat-treated at 600 ° C. for 60 minutes under reduced pressure.
(5) A ring sample having an outer diameter of 25 mm and an inner diameter of 15 mm was formed by compressing the iron powder heat-treated in (4) using a carbide die. Thickness is 4mm and this sample is for magnetic measurement of magnetic flux density and coercive force.
(6) A cylindrical sample having a thickness of 2 mm was prepared by compression using the iron powder formed in (5) using a cylindrical shape having a diameter of 11.3 mm. The molding pressure was 1.0 to 1.5 GPa. This sample is for specific resistance measurement.
(7) The sample formed in (6) was heat-treated at 600 ° C. under a reduced pressure of 5 × 10 −5 torr.
（比較例１）
［試料形成］
（１）原料鉄粉４０ｇに対して８mLのＭｇＦ2処理液を用意した。これは粒径１００μｍでコート厚１４０nmに相当する。膜厚は鉄粉量増加で薄膜側，処理液複数回塗布で厚い側を作製した。処理液添加し、鉄粉全体が濡れるのが確認できるまで混合した。
（２）（１）の処理鉄粉を２〜５torrの減圧下で溶媒のメタノール除去を行った。
（３）（２）の溶媒の除去を行った鉄粉を石英製ボートに移し、５×１０-5torrの減圧下で２００℃、３０分と３５０℃、３０分の熱処理を行って原料鉄粉を作製した。
(Comparative Example 1)
[Sample formation]
(1) 8 mL of MgF 2 treatment solution was prepared for 40 g of raw iron powder. This corresponds to a particle thickness of 100 μm and a coat thickness of 140 nm. The thickness of the thin film was increased by increasing the amount of iron powder, and the thicker side was prepared by applying multiple treatment solutions. The treatment liquid was added and mixed until it was confirmed that the entire iron powder was wet.
(2) The treated iron powder of (1) was subjected to methanol removal of the solvent under reduced pressure of 2 to 5 torr.
(3) The iron powder from which the solvent of (2) has been removed is transferred to a quartz boat and subjected to heat treatment at 200 ° C., 30 minutes and 350 ° C. for 30 minutes under a reduced pressure of 5 × 10 −5 torr, and the raw material iron Powder was prepared.
その後は、実施例１と同様の条件で予備熱処理や熱処理，磁気測定用のリング試料作製及び比抵抗値測定用の円柱試料を作成した。 Thereafter, pre-heat treatment, heat treatment, ring sample preparation for magnetic measurement, and cylindrical sample for specific resistance measurement were prepared under the same conditions as in Example 1.
［比抵抗測定］
比抵抗測定は４端子法を用いた。
[Specific resistance measurement]
The specific resistance measurement used the 4-terminal method.
リング試料は１次巻線１５０ターン，２次巻線２０ターンを行い、ＤＣで１００００Ａ／ｍ励磁時の飽和磁束密度Ｂと４００HzでＢを１Ｔまで励磁したときのヒステリシスループから損失Ｗを求めた。その結果を表１に示す。成形圧１.５ＧＰａで作製した実施例１の損失Ｗは、４５Ｗ／kgであり、成形圧１.５ＧＰａで作製した比較例１の損失Ｗは、６０Ｗ／kgと比較して良好であった。 The ring sample was subjected to 150 turns of the primary winding and 20 turns of the secondary winding, and the loss W was obtained from the saturation magnetic flux density B when 10000 A / m was excited with DC and the hysteresis loop when B was excited to 1 T at 400 Hz. . The results are shown in Table 1. The loss W of Example 1 manufactured at a molding pressure of 1.5 GPa was 45 W / kg, and the loss W of Comparative Example 1 manufactured at a molding pressure of 1.5 GPa was better than that of 60 W / kg.
ここで、図１に、実施例１の条件で作製した試料と、従来法である比較例１に相当する標準処理（手塗り）で作製した試料とにおける成形圧と比抵抗の関係を示す。比較例１では成形圧の上昇に伴い比抵抗値が低下する。これに対し、ロータリエバポレータを用いた実施例１の試料は、１.０ＧＰａでは０.０６ｍΩ・ｍと従来法より低いものの、成形圧が変化しても比抵抗値の変動は無く、１.５ＧＰａでは従来法である比較例１の比抵抗値より高い結果となった。これより、本実施例の試料では、密度が成形圧の上昇に伴って、比抵抗が低下しないことがわかる。 Here, FIG. 1 shows the relationship between the molding pressure and the specific resistance of a sample produced under the conditions of Example 1 and a sample produced by standard processing (hand-painted) corresponding to Comparative Example 1 which is a conventional method. In Comparative Example 1, the specific resistance value decreases as the molding pressure increases. On the other hand, the sample of Example 1 using a rotary evaporator has a lower resistivity value of 1.0 GPa even when the molding pressure changes, although it is 0.06 mΩ · m at 1.0 GPa, which is lower than the conventional method. Then, it was a result higher than the specific resistance value of the comparative example 1 which is a conventional method. From this, it can be seen that the specific resistance of the sample of this example does not decrease as the molding pressure increases.
また、図２には、実施例１の条件で作製した試料と、従来法である比較例１に相当する標準処理（手塗り）で作製した試料とにおける密度の成形圧依存性を示す。いずれの試料も成形圧増加により密度増加しており、図１の成形圧１.５ＧＰａにおける比抵抗の逆転現象は、塗布方法の変更による性能向上であることがわかる。 Further, FIG. 2 shows the molding pressure dependence of the density of a sample manufactured under the conditions of Example 1 and a sample manufactured by standard processing (hand coating) corresponding to Comparative Example 1 which is a conventional method. All the samples increase in density due to an increase in molding pressure, and it can be seen that the reversal phenomenon of specific resistance at a molding pressure of 1.5 GPa in FIG.
図３は、従来法により形成したフッ化マグネシウムコート層の断面ＴＥＭ観察結果である。図３の左図の明視野像から、フッ化物層は粒状のフッ化物よりなっていることがわかる。ＥＤＸ組成分析より、鉄はフッ化物層内には存在しないことがわかる。また、酸素は鉄表面にのみ存在し、これは鉄粉の自然酸化物Ｆｅ2Ｏ3であることが電子線回折よりわかっている。粒径はおおむね１０〜１００nmで分布しており、電子線回折結果よりＭｇＦ2単層であることがわかった。 FIG. 3 is a cross-sectional TEM observation result of the magnesium fluoride coat layer formed by the conventional method. It can be seen from the bright-field image in the left diagram of FIG. 3 that the fluoride layer is made of granular fluoride. From the EDX composition analysis, it can be seen that iron is not present in the fluoride layer. Further, it is known from electron beam diffraction that oxygen exists only on the iron surface, which is a natural oxide Fe 2 O 3 of iron powder. The particle size was generally distributed at 10 to 100 nm, and it was found from the electron diffraction results that it was a MgF 2 single layer.
図４は、ロータリエバポレータにより、ガスアトマイズ粉への塗布，乾燥した直後のＭｇＦ2の形態をＳＥＭ観察したものである。球形の鉄粉上に鱗片状のコート層が形成されていることがわかる。 FIG. 4 is an SEM observation of the morphology of MgF 2 immediately after application to a gas atomized powder and drying using a rotary evaporator. It can be seen that a scaly coat layer is formed on the spherical iron powder.
図５は本発明に係る実施例のフッ化マグネシウムコート層の断面ＴＥＭ観察結果である。明視野像はあきらかに従来法と異なり、繊維状の形状が観察される。また、粒状の結晶も観察される。ＥＤＸ組成分析結果から、今回は鉄，酸素ともフッ化マグネシウム層内に分布していることがわかった。また、マグネシウムの分布も層内全体に均一化している。電子線回折結果から、この繊維状のものはＦｅ3Ｏ4であることがわかった。繊維状ではあるが、濃淡をもって広がっていることから、これは薄片の断面をみていると考えられる。その他に粒状のＭｇＦ2も存在する。この構造の由来は以下と推定できる。 FIG. 5 is a cross-sectional TEM observation result of the magnesium fluoride coating layer of the example according to the present invention. The bright field image clearly has a fibrous shape unlike the conventional method. Granular crystals are also observed. From the EDX composition analysis results, it was found that both iron and oxygen were distributed in the magnesium fluoride layer this time. Also, the distribution of magnesium is uniform throughout the layer. From the electron diffraction results, it was found that this fibrous material was Fe 3 O 4 . Although it is fibrous, it spreads with shading, so it is thought that this is a cross section of a flake. In addition, granular MgF 2 exists. The origin of this structure can be estimated as follows.
ロータリエバポレータ内では、ガラスビーズにより鉄粉は管壁にすりつけられる。このとき自然酸化膜と、おそらく金属鉄もはがされ、鱗片状に部分的に剥離し、鉄粉本体との間に隙間ができる。ここへ処理液が入り込み、そのまま乾燥すると鱗片状の鉄粉と金属鉄，Ｆｅ2Ｏ3の混じった表面層ができる。エバポレータ内部は減圧下で、アルコールが還元性であるので酸化はない。ここで、試料を取り出し、成形するとこの構造のまま圧縮される。歪取り熱処理の際、Ｆｅ2Ｏ3は還元されてＦｅ3Ｏ4となるか、あるいは金属鉄がアルコールから揮発する水から酸素をとって酸化される。この断面を観察するので、上記繊維状の酸化物が残留する。なお、工程の選択により、Ｆｅ3Ｏ4のほか剥離したＦｅ2Ｏ3およびＦｅがそのまま残留する場合もあった。 In the rotary evaporator, iron powder is rubbed against the tube wall by glass beads. At this time, the natural oxide film and possibly the metallic iron are peeled off, and partly peeled off in a scaly shape to form a gap between the iron powder body. When the treatment solution enters here and is dried as it is, a surface layer containing scale-like iron powder, metallic iron, and Fe 2 O 3 is formed. The inside of the evaporator does not oxidize because the alcohol is reducing under reduced pressure. Here, when the sample is taken out and molded, it is compressed in this structure. During the strain relief heat treatment, Fe 2 O 3 is reduced to Fe 3 O 4 , or the metallic iron is oxidized by taking oxygen from the water volatilized from the alcohol. Since this cross section is observed, the fibrous oxide remains. Depending on the selection of the process, the peeled Fe 2 O 3 and Fe in addition to Fe 3 O 4 may remain as they are.
本方法によれば、フッ化マグネシウムを層内に均一に分布させることができ、圧縮による絶縁層の形状変化が小さいので、耐圧縮性に優れていると考えられる。 According to this method, magnesium fluoride can be uniformly distributed in the layer, and the shape change of the insulating layer due to compression is small, so it is considered that the compression resistance is excellent.
なお、上記構造の成立にはロータリエバポレータの使用が必須ではなく、圧力を与えながら処理できる装置、例えば減圧可能なコンクリートミキサーのようなものでも使用は可能である。 Note that the use of a rotary evaporator is not essential for the establishment of the above structure, and an apparatus capable of processing while applying pressure, such as a concrete mixer capable of reducing pressure, can also be used.
また、フッ化物絶縁物としてはＭｇＦ2のほか、ＣａＦ2，ＮｄＦ3などアルカリ土類金属，希土類金属フッ化物でも利用できる。 Further, as the fluoride insulator, MgF 2 , alkaline earth metals such as CaF 2 and NdF 3 , and rare earth metal fluorides can be used.
（実施例２）
実施例２では、以下に記載する点を除き、実施例１と同様の手法で鉄粉を作製した。平均粒径１５０nmのガスアトマイズ鉄粉１００ｇに直径５mmのガラスビーズ１００ｇを混ぜ、フラスコに入れた。これにＭｇＦ2処理液を３００nm相当の量を添加し、１００Ｐａ、毎分１４０回転で回しながら１.５時間乾燥させた。乾燥後６００℃、１ｈの真空熱処理を行って原料鉄粉を製作した。これを平均圧力１.５ＧＰａで円柱試料を形成し、比抵抗測定した。図１の例と比較すると、比抵抗は０.１１ｍΩ・ｍと大きくなった。密度は７.５５Ｍｇ／ｍ3であり、比較例１の値よりおおきい。１.５ＧＰａで、リング試料製作し、比較したところ、１０kA／ｍ励磁でのＢは比較例１の１.４Ｔに対し１.５Ｔと大きくなった。損失値は手塗りが６０Ｗ／kgであるのに対し、３５Ｗ／kgと小さくなった。比較例１と実施例２での円柱試料の分析により膜厚は、従来例の１５０nmに対し、実施例では１２５nmと薄くできている。投入量３００nmが仕上がりで１／３になったのは、ガラスビーズへのＭｇＦ2付着による膜厚減少による。また、鱗片状の鉄酸化物が同様に観察された。飽和磁束密度Ｂが高いのは薄い膜厚によると考えられる。また、薄い膜厚でも比抵抗が高い理由は、先に示したＭｇＦ2均一化と鉄酸化物による鉄粉の接触遮断によると考えられる。
(Example 2)
In Example 2, iron powder was produced in the same manner as in Example 1 except for the points described below. 100 g of gas atomized iron powder having an average particle diameter of 150 nm and 100 g of glass beads having a diameter of 5 mm were mixed and placed in a flask. An amount equivalent to 300 nm of the MgF 2 treatment solution was added thereto and dried for 1.5 hours while rotating at 100 Pa at 140 rpm. After drying, vacuum heat treatment was performed at 600 ° C. for 1 hour to produce raw iron powder. A cylindrical sample was formed at an average pressure of 1.5 GPa, and the specific resistance was measured. Compared with the example of FIG. 1, the specific resistance was as large as 0.11 mΩ · m. The density is 7.55 Mg / m 3, which is larger than the value of Comparative Example 1. When a ring sample was manufactured at 1.5 GPa and compared, B at 10 kA / m excitation was 1.5 T larger than 1.4 T in Comparative Example 1. The loss value was as small as 35 W / kg, compared with 60 W / kg for hand coating. According to the analysis of the cylindrical samples in Comparative Example 1 and Example 2, the film thickness was made as thin as 125 nm in the example, compared to 150 nm in the conventional example. The reason why the input amount of 300 nm has been reduced to 1/3 is that the film thickness has decreased due to MgF 2 adhesion to the glass beads. In addition, scaly iron oxide was observed in the same manner. The high saturation magnetic flux density B is thought to be due to the thin film thickness. In addition, the reason why the specific resistance is high even with a thin film thickness is considered to be due to the above-described uniform MgF 2 and the contact blocking of iron powder by iron oxide.
（実施例３）
実施例３では、以下に記載する点を除き、実施例１と同様の手法で鉄粉を作製した。
(Example 3)
In Example 3, iron powder was produced in the same manner as in Example 1 except for the points described below.
平均粒径１５０nmのガスアトマイズ鉄粉１００ｇをフラスコに入れた。これにＭｇＦ2処理液を１５０nm相当の量を用意した。別途大気中で粒径１００nmの水アトマイズ鉄粉を６時間ボールミルを行い、開口５μｍのふるいを通過した厚さ０.５μｍの鉄酸化物のフレーク０.１ｇを準備した。これを処理液に添加しよく攪拌したのちフラスコに添加、１００Ｐａ、毎分１４０回転で回しながら１.５時間乾燥させた。乾燥後６００℃、１ｈの真空熱処理を行って原料鉄粉を製作した。これを平均圧力１.５ＧＰａで円柱試料を形成し、比抵抗測定した。比抵抗は０.０８ｍΩ・cmと大きくなった。密度は７.５０Mg／ｍ3であり、１.５ＧＰａで、リング試料製作し、比較したところ、１０kA／ｍ励磁でのＢは比較例１の１.４Ｔに対し１.４５Ｔと大きくなった。ここで、損失Ｗは比較例１の手塗りが６０Ｗ／kgであるのに対し、実施例３における試料の損失Ｗは４４Ｗ／kgと小さい。今回ガラスビーズを投入していないが比抵抗増加したのは、鉄酸化物の効果と考えられる。 100 g of gas atomized iron powder having an average particle size of 150 nm was placed in a flask. An amount equivalent to 150 nm of MgF 2 treatment solution was prepared. Separately, water atomized iron powder having a particle size of 100 nm was ball-milled in the atmosphere for 6 hours to prepare 0.1 g of iron oxide flakes having a thickness of 0.5 μm that passed through a sieve having an opening of 5 μm. This was added to the treatment liquid and stirred well, then added to the flask and dried for 1.5 hours while rotating at 100 Pa at 140 rpm. After drying, vacuum heat treatment was performed at 600 ° C. for 1 hour to produce raw iron powder. A cylindrical sample was formed at an average pressure of 1.5 GPa, and the specific resistance was measured. The specific resistance increased to 0.08 mΩ · cm. The density was 7.50 Mg / m 3 , and a ring sample was manufactured at 1.5 GPa. As a result, B at 10 kA / m excitation was 1.45 T as compared with 1.4 T in Comparative Example 1. Here, the loss W is 60 W / kg in the hand-painting of Comparative Example 1, whereas the loss W of the sample in Example 3 is as small as 44 W / kg. Although the glass beads were not added this time, the increase in specific resistance is thought to be due to the effect of iron oxide.
（実施例４）
実施例４では、以下に記載する点を除き、実施例１と同様の手法で鉄粉を作製した。具体的には、平均粒径１５０nmのガスアトマイズ鉄粉１００ｇに直径５mmのガラスビーズ１００ｇを混ぜ、フラスコに入れた。これにＭｇＦ2処理液を３００nm相当の量を添加し、１００Ｐａで回転数を毎分１０から２００回転と変えて１.５時間乾燥させる実験を行った。乾燥後６００℃、１ｈの真空熱処理を行って原料鉄粉を製作した。これを平均圧力１.５ＧＰａで円柱試料を形成し、比抵抗測定した。
Example 4
In Example 4, iron powder was produced in the same manner as in Example 1 except for the points described below. Specifically, 100 g of glass beads having a diameter of 5 mm were mixed with 100 g of gas atomized iron powder having an average particle diameter of 150 nm and placed in a flask. An experiment was performed in which an amount equivalent to 300 nm of MgF 2 treatment solution was added thereto and dried at 100 Pa for 1.5 hours while changing the rotational speed from 10 to 200 revolutions per minute. After drying, vacuum heat treatment was performed at 600 ° C. for 1 hour to produce raw iron powder. A cylindrical sample was formed at an average pressure of 1.5 GPa, and the specific resistance was measured.
図６に回転数と成形体比抵抗の関係を示す。比抵抗の小さい回転数１０および５０回転では比抵抗は０.０１ｍΩ・ｍで小さく、また、構造観察からは鱗片状の酸化物は観察されなかった。それ以上では比抵抗は増加し、構造から鱗片状酸化物が観察できた。２００回転では比抵抗は高いものの、１００回転の試料より低下した。構造からは鱗片状酸化物は形成はされたものの量は少なく、また絶縁層全体の膜厚分布が大きかった。これは、ビーズと鉄粉が同時に回転したため、衝撃が低下し、塗布も不均一になったことによる。 FIG. 6 shows the relationship between the rotational speed and the specific resistance of the compact. At a rotational speed of 10 and 50 with a small specific resistance, the specific resistance was as small as 0.01 mΩ · m, and no scaly oxide was observed from structural observation. Above that, the specific resistance increased and scaly oxides could be observed from the structure. Although the specific resistance was high at 200 rpm, it was lower than that of the sample at 100 rpm. From the structure, scaly oxide was formed, but the amount was small, and the film thickness distribution of the whole insulating layer was large. This is because the beads and iron powder were rotated at the same time, so the impact was reduced and the coating became non-uniform.
（実施例５）
実施例５では、以下に記載する点を除き、実施例１と同様の手法で鉄粉を作製した。平均粒径７０nmのガスアトマイズ鉄粉１００ｇに直径５mmのガラスビーズ１００ｇを混ぜ、フラスコに入れた。これにＭｇＦ2処理液を標準処理で３００nm相当の量を添加し、１００Ｐａ、毎分１４０回転で回しながら１.５時間乾燥させた。乾燥後６００℃、１ｈの真空熱処理を行って原料鉄粉を製作した。これを平均圧力１.５ＧＰａで円柱試料を形成し、比抵抗測定した。比抵抗は０.０８ｍΩ・ｍと大きくなったが粒径１５０nmの場合より低下している。
(Example 5)
In Example 5, iron powder was produced by the same method as in Example 1 except the points described below. 100 g of gas atomized iron powder having an average particle diameter of 70 nm was mixed with 100 g of glass beads having a diameter of 5 mm and put into a flask. An amount equivalent to 300 nm was added to the MgF 2 treatment solution by standard treatment, and dried for 1.5 hours while rotating at 100 Pa and 140 revolutions per minute. After drying, vacuum heat treatment was performed at 600 ° C. for 1 hour to produce raw iron powder. A cylindrical sample was formed at an average pressure of 1.5 GPa, and the specific resistance was measured. The specific resistance is as large as 0.08 mΩ · m, but is lower than when the particle size is 150 nm.
構造観察からは、鱗片状酸化物は粒子に近くなっている。これは粒径低下に伴い、鉄粉の曲率半径が小さくなって粉砕されやすくなったことによる。ここで、実施例５の飽和磁束密度Ｂは１.５０Ｔであり、損失Ｗは４０Ｗ／kgであり、いずれも比較例１の場合と比較して良好であった。 From the structural observation, the scaly oxide is close to particles. This is because the radius of curvature of the iron powder is reduced and the powder is easily pulverized as the particle size decreases. Here, the saturation magnetic flux density B of Example 5 was 1.50 T, and the loss W was 40 W / kg, both of which were better than those of Comparative Example 1.
（実施例６）
実施例６では、以下に記載する点を除き、実施例１と同様の手法で鉄粉を作製した。平均粒径４０nmのガスアトマイズ鉄粉１００ｇに直径５mmのガラスビーズ１００ｇを混ぜ、フラスコに入れた。これにＭｇＦ2処理液を標準処理で３００nm相当の量を添加し、１００Ｐａ、毎分１４０回転で回しながら１.５時間乾燥させた。乾燥後６００℃、１ｈの真空熱処理を行って原料鉄粉を製作した。これを平均圧力１.５ＧＰａで円柱試料を形成し、比抵抗測定した。比抵抗は０.０２ｍΩ・ｍと比較例１より低下した。
(Example 6)
In Example 6, iron powder was produced in the same manner as in Example 1 except for the points described below. 100 g of gas atomized iron powder having an average particle diameter of 40 nm and 100 g of glass beads having a diameter of 5 mm were mixed and placed in a flask. An amount equivalent to 300 nm was added to the MgF 2 treatment solution by standard treatment, and dried for 1.5 hours while rotating at 100 Pa and 140 revolutions per minute. After drying, vacuum heat treatment was performed at 600 ° C. for 1 hour to produce raw iron powder. A cylindrical sample was formed at an average pressure of 1.5 GPa, and the specific resistance was measured. The specific resistance was 0.02 mΩ · m, which was lower than that of Comparative Example 1.
構造観察からは、鱗片状酸化物は存在するが、ＭｇＦ2粒子より細かい粒子に近くなっている。これは粒径低下に伴い、鉄粉の曲率半径が小さくなって粉砕されやすくなったことによる。 From the structural observation, scaly oxides are present, but are closer to finer particles than MgF 2 particles. This is because the radius of curvature of the iron powder is reduced and the powder is easily pulverized as the particle size decreases.
図７に鱗片の長さと比抵抗で整理した関係を示す。酸化物混合が十分効果を発揮するのは、平均鱗片長は１００nm以上であり、これはＭｇＦ2の平均粒径５０nmの２倍にあたる。 FIG. 7 shows the relationship organized by scale length and specific resistance. The reason why the oxide mixture is sufficiently effective is that the average scale length is 100 nm or more, which is twice the average particle diameter of MgF 2 of 50 nm.
Claims (10)
前記絶縁層に、粒状のフッ化物と、鉄酸化物からなる剥離体と、が混在していることを特徴とする圧粉磁心。 In a powder magnetic core formed by compressing and molding an insulating layer containing fluoride on the surface of iron or iron-based alloy powder,
A powder magnetic core, wherein a granular fluoride and a peeled body made of iron oxide are mixed in the insulating layer.
前記絶縁層を形成する際に、前記鉄又は鉄を主成分とする合金の粉末に、一定の圧力を与えながら処理液を塗布及び乾燥させることを特徴とする圧粉磁心製造方法。 In the method of manufacturing a powder magnetic core in which the surface of a powder of iron or an alloy containing iron as a main component is formed by compressing and forming an insulating layer containing fluoride.
A method for producing a dust core, wherein, when forming the insulating layer, a treatment liquid is applied and dried while applying a certain pressure to the powder of iron or an alloy containing iron as a main component.
前記絶縁層が、フッ化物と、鱗片状の鉄酸化物と、を有することを特徴とする圧粉磁心。 In a powder magnetic core formed by compressing and molding an insulating layer containing fluoride on the surface of iron or iron-based alloy powder,
The dust core according to claim 1, wherein the insulating layer includes fluoride and scaly iron oxide.
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