JP2005093350A

JP2005093350A - Insulation coating, powder for magnetic core, and dust core, and manufacturing method of those

Info

Publication number: JP2005093350A
Application number: JP2003328311A
Authority: JP
Inventors: Shin Tajima; 伸田島; Takeshi Hattori; 毅服部; Mikio Kondo; 幹夫近藤; Masaki Sugiyama; 昌揮杉山; Hideshi Kishimoto; 秀史岸本; Tadayoshi Kikko; 忠義亀甲
Original assignee: Fine Sinter Co Ltd; Toyota Motor Corp; Toyota Central R&D Labs Inc
Current assignee: Fine Sinter Co Ltd; Toyota Motor Corp; Toyota Central R&D Labs Inc
Priority date: 2003-09-19
Filing date: 2003-09-19
Publication date: 2005-04-07

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation film suitable for covering powder for a magnetic core and superior in heat resistance. <P>SOLUTION: This is an insulation coating in which indispensable constituting elements are a first element group composed of P and O, and a second element to produce positive ions of divalence or more in which an ion radius in 6 coordination number defined by Shannon is not less than 0.073 nm, and in which B is not substantially contained. Because the second element with a large ion radius is introduced as a mesh modifying structure into a mesh forming structure formed by the first element group, the heat resistance of the insulation coating can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、耐熱性に優れる絶縁皮膜、その絶縁皮膜で被覆された磁心用粉末、その磁心用粉末からなる圧粉磁心およびそれらの製造方法に関するものである。 The present invention relates to an insulating film having excellent heat resistance, a magnetic core powder coated with the insulating film, a dust core made of the magnetic core powder, and a method for producing the same.

変圧器（トランス）、電動機（モータ）、発電機、スピーカ、誘導加熱器、各種アクチュエータ等、我々の周囲には電磁気を利用した製品が多々ある。これらの製品は交番磁界を利用したものが多く、局所的に大きな交番磁界を効率的に得るために、通常、磁心（軟磁石）をその交番磁界中に設けている。
このような磁心は、その性質上、先ず、交番磁界中で大きな磁束密度が得られることが求められる。次に、交番磁界中で使用したときに、その周波数に応じて生じる高周波損失が少ないことが求められる。この高周波損失（鉄損）には、渦電流損失、ヒステリシス損失および残留損失があるが、主に問題となるのは、渦電流損失とヒステリシス損失である。さらに、磁心が交番磁界に追従して素早く高磁束密度となるには、その保磁力が小さいことも重要である。なお、この保磁力を低減することで、（初期）透磁率の向上とヒステリシス損失の低減とを併せて図れる。 There are many products that use electromagnetism around us, such as transformers, motors, generators, speakers, induction heaters, and various actuators. Many of these products use an alternating magnetic field. In order to efficiently obtain a large alternating magnetic field locally, a magnetic core (soft magnet) is usually provided in the alternating magnetic field.
Due to the nature of such a magnetic core, first, it is required that a large magnetic flux density be obtained in an alternating magnetic field. Next, when used in an alternating magnetic field, it is required that the high-frequency loss generated according to the frequency is small. The high-frequency loss (iron loss) includes eddy current loss, hysteresis loss, and residual loss, but the main problems are eddy current loss and hysteresis loss. Further, in order for the magnetic core to follow the alternating magnetic field and quickly reach a high magnetic flux density, it is also important that the coercive force is small. By reducing the coercive force, it is possible to improve the (initial) magnetic permeability and reduce the hysteresis loss.

ところが、これらの要求を同時に満たすことは難しく、単なる鉄心は勿論、薄いケイ素鋼板を積層した従来の磁心等では、十分な性能が得られていなかった。そこで、最近では、絶縁皮膜で被覆した磁性粉末（磁心用粉末）を加圧成形した圧粉磁心を用いることで、この課題の解決を図る傾向にある。すなわち、磁性粉末の各粒子を絶縁皮膜で被覆することで比抵抗を増大させて圧粉磁心の高周波損失を低減させるとともに、その粉末を高圧成形して高密度の圧粉磁心を得ることで磁束密度の増加を図ろうとするものである。このような圧粉磁心は、下記の特許文献１等に開示されている。例えば、特許文献１では、先ず、磁性粉末である純鉄粉にリン酸溶液を接触させ、その純鉄粉の表面にリン酸塩（リン酸鉄）皮膜からなる絶縁皮膜を生成し、得られた粉末を加圧成形して圧粉磁心としている。 However, it is difficult to satisfy these requirements at the same time, and a conventional magnetic core in which thin silicon steel plates are laminated as well as a simple iron core has not obtained sufficient performance. Thus, recently, there is a tendency to solve this problem by using a powder magnetic core obtained by press-molding magnetic powder (magnetic core powder) coated with an insulating film. That is, by covering each particle of magnetic powder with an insulating film, the specific resistance is increased to reduce the high-frequency loss of the powder magnetic core, and the magnetic flux is obtained by high-pressure molding the powder to obtain a high-density powder magnetic core. It is intended to increase the density. Such a dust core is disclosed in Patent Document 1 below. For example, in Patent Document 1, first, a phosphoric acid solution is brought into contact with pure iron powder that is magnetic powder, and an insulating film made of a phosphate (iron phosphate) film is generated on the surface of the pure iron powder. The powder core is pressed to form a powder magnetic core.

特表２０００−５０４７８５号公報JP 2000-504785 gazette 特開平６−１３２１０９号公報JP-A-6-132109 特許第２７１０１５２号公報Japanese Patent No. 2710152

しかし、これまでの圧粉磁心は、未だその性能が十分とはいえなかった。その理由は、先ず、従来の圧粉磁心が、金型寿命等を考慮した低い圧力で磁性粉末を成形していたため、低密度で十分に高い磁束密度が得られなかったことにある。
もっとも、本出願人は、この点に関しては、既に解決済みである。すなわち、超高圧成形を可能とする技術を開発し、絶縁被覆された磁性粉末から真密度に近い高密度化された圧粉磁心を得ることに成功して、既に複数の出願を行っている。 However, the performance of the dust cores so far has not been sufficient. The reason is that a conventional powder magnetic core molded the magnetic powder at a low pressure in consideration of the mold life and the like, so that a sufficiently high magnetic flux density could not be obtained at a low density.
However, the applicant has already solved this point. In other words, a technology that enables ultra-high pressure molding has been developed, and a powder core having a high density close to the true density has been successfully obtained from magnetic powder coated with insulation, and a plurality of applications have already been filed.

次に、従来の圧粉磁心の性能が不十分であったもう一つの理由は、単に絶縁皮膜を磁性粉末の表面に設けるのみでは、高周波損失が十分に低減されなかったことにある。なぜなら、比抵抗を増加させて高周波損失中の渦電流損失を低減させることはこれまでも行われていたが、ヒステリシス損失の低減自体はあまり図られていなかったからである。勿論、渦電流損失に比較してヒステリシス損失を無視し得るような周波数域（超高周波数域）でのみ使用される圧粉磁心なら、あまり問題は無いかもしれない。しかし、多くの製品は、例えば、数百ｋＨｚ以下程度の周波数域で使用されることが多く、このような周波数領域では、圧粉磁心のヒステリシス損失を必ずしも無視し得ない。 Next, another reason why the performance of the conventional dust core is insufficient is that the high-frequency loss is not sufficiently reduced simply by providing an insulating film on the surface of the magnetic powder. This is because although the specific resistance has been increased to reduce the eddy current loss during the high frequency loss, the hysteresis loss itself has not been much reduced. Of course, if the dust core is used only in a frequency range (ultra-high frequency range) in which hysteresis loss can be ignored compared to eddy current loss, there may be no problem. However, many products are often used in a frequency range of, for example, several hundred kHz or less, and in such a frequency range, the hysteresis loss of the dust core cannot always be ignored.

前述したが、圧粉磁心のヒステリシス損失の低減を図るには、圧粉磁心の保磁力の低減が有効である。この保磁力は、磁性粉末粒子内に残留する歪の影響を受け、その歪が多いと保磁力も大きくなる。圧粉磁心の製法上、加圧成形後にその粉末粒子内に多かれ少なかれ残留歪が生じることは避け難い。従って、ヒステリシス損失の低減のためには、磁性粉末粒子内に一旦生じたその残留歪を除去することが必要となる。そして、この歪の除去には、圧粉磁心に残留応力除去焼き鈍し等の熱処理を施すのが有効である。
この熱処理は、磁性粉末の種類にも依るが、一般的なＦｅを主成分とする磁性粉末の場合、その内部の歪を十分に除去するためには、４５０℃以上、さらには５００℃程度までそれを加熱することが望ましい。 As described above, in order to reduce the hysteresis loss of the dust core, it is effective to reduce the coercive force of the dust core. This coercive force is affected by the strain remaining in the magnetic powder particles, and the coercive force increases as the strain increases. Due to the manufacturing method of the dust core, it is unavoidable that more or less residual strain is generated in the powder particles after pressure molding. Therefore, in order to reduce hysteresis loss, it is necessary to remove the residual strain once generated in the magnetic powder particles. In order to remove the strain, it is effective to subject the dust core to heat treatment such as annealing for removing residual stress.
Although this heat treatment depends on the type of magnetic powder, in the case of a general magnetic powder mainly composed of Fe, in order to sufficiently remove the internal strain, it is 450 ° C. or higher, further up to about 500 ° C. It is desirable to heat it.

ところが、圧粉磁心をそこまで高温加熱すると、磁性粉末の絶縁皮膜として従来用いられてきた樹脂皮膜は分解して消失し、前述のリン酸塩被膜（化成被膜）等でも、結晶化して焼結・凝集を生じたり、絶縁皮膜が磁性粉末と反応したりして、絶縁皮膜が破壊されることが明らかとなった。これでは、比抵抗が急激に低下して渦電流損失の増大を招き、圧粉磁心の高周波損失を逆に増加させる結果となってしまい、上記熱処理を行うことが無意味となる。ここで、耐熱性が比較的高いＳｉＯ₂ 、Ａｌ₂Ｏ₃ 、ＺｒＯ₂ 、ＴｉＯ₂等の酸化物系の絶縁皮膜を用いることも考えられる。しかし、数十ｎｍの薄い酸化皮膜を磁性粉末上にピンホール無く均一にコーティングすることは技術的に困難である。また、コストも非常に高くなるため、工業的に有効ではない。一方、その酸化皮膜が１００ｎｍ以上に厚くなると、得られた圧粉磁心の磁束密度が低くなるため、やはり好ましくない。 However, when the powder magnetic core is heated to such a high temperature, the resin film that has been used as an insulating film of the magnetic powder is decomposed and disappears, and even the above-mentioned phosphate film (chemical conversion film) is crystallized and sintered. -It became clear that the insulation film was destroyed by agglomeration or the insulation film reacting with the magnetic powder. In this case, the specific resistance is drastically reduced, leading to an increase in eddy current loss, resulting in an increase in the high frequency loss of the dust core, which makes it meaningless to perform the heat treatment. Here, it is also conceivable to use an oxide-based insulating film such as SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ having relatively high heat resistance. However, it is technically difficult to uniformly coat a thin oxide film of several tens of nm on a magnetic powder without pinholes. In addition, the cost is very high, which is not industrially effective. On the other hand, when the oxide film is thicker than 100 nm, the magnetic flux density of the obtained dust core is lowered, which is not preferable.

そこで、例えば、上記の特許文献２や特許文献３には、クロム（Ｃｒ）やマグネシウム（Ｍｇ）を必須構成元素とした、耐熱性を高めたガラス状絶縁層に関する開示がある。
しかし、特許文献３にもあるように、Ｃｒは環境上、その使用が好ましくない。また、本発明者が調査研究したところ、Ｍｇを必須元素とするガラス状絶縁層は、確かに従来のものよりも耐熱性が向上していると思われるが、未だ、その耐熱性は十分ではなかった。 Therefore, for example, Patent Document 2 and Patent Document 3 described above disclose a glass-like insulating layer with improved heat resistance, in which chromium (Cr) or magnesium (Mg) is an essential constituent element.
However, as disclosed in Patent Document 3, it is not preferable to use Cr because of the environment. In addition, as a result of investigation and research by the present inventor, it seems that the heat resistance of the glassy insulating layer containing Mg as an essential element is certainly improved compared to the conventional one, but the heat resistance is still insufficient. There wasn't.

本発明は、このような事情に鑑みて為されたものであり、耐熱性を向上させ得る絶縁皮膜およびその製造方法を提供することを目的とする。
また、その絶縁皮膜で被覆された磁性粉末からなる磁心用粉末およびその製造方法を提供することを目的とする。
さらに、その磁心用粉末を用いて得られる圧粉磁心とその製造方法を提供することを目的とする。 This invention is made | formed in view of such a situation, and it aims at providing the insulating film which can improve heat resistance, and its manufacturing method.
Moreover, it aims at providing the powder for magnetic cores which consists of a magnetic powder coat | covered with the insulating film, and its manufacturing method.
Furthermore, it aims at providing the dust core obtained using the powder for magnetic cores, and its manufacturing method.

なお、これまでは、絶縁皮膜の耐熱性を向上させる目的として、磁性粉末内の残留歪とり（応力除去）を行う場合を例示したが、それに限られるものではない。例えば、焼鈍等の熱処理を行わない場合でも、絶縁皮膜の耐熱性を向上させることで、磁心等の高温域における特性を安定させることが可能となる。 Heretofore, the case of performing residual strain removal (stress removal) in the magnetic powder has been exemplified for the purpose of improving the heat resistance of the insulating film, but is not limited thereto. For example, even when heat treatment such as annealing is not performed, it is possible to stabilize characteristics in a high temperature region such as a magnetic core by improving the heat resistance of the insulating film.

本発明者はこの課題を解決すべく鋭意研究し、試行錯誤を重ねた結果、イオン半径の比較的大きな元素を必須構成元素とする絶縁皮膜を用いることにより、その耐熱性を向上させ得ることを新たに見い出し、本発明を完成するに至った。
（絶縁皮膜）
すなわち、本発明の絶縁皮膜は、ＰとＯとからなる第１元素群と、シャノン（Ｓｈａｎｎｏｎ，Ｒ，Ｄ）により定義された６配位のイオン半径が０．０７３ｎｍ以上である２価以上の陽イオンを生じ得る第２元素とを必須構成元素としＢを実質的に含まないことを特徴とする。なお、磁性粉末がＦｅを主成分とするときは、前記第１元素群には、ＰとＯの他に、反応時に磁性粉末から混入するＦｅが含まれることもある。 The present inventor has intensively studied to solve this problem, and as a result of trial and error, by using an insulating film having an element having a relatively large ionic radius as an essential constituent element, the heat resistance can be improved. A new discovery was made and the present invention was completed.
(Insulating film)
That is, the insulating film of the present invention has a first element group consisting of P and O, and a bivalent or higher valence having a six-coordinate ion radius defined by Shannon (Shannon, R, D) of 0.073 nm or more. The second element capable of generating a cation is an essential constituent element and is substantially free of B. When the magnetic powder is mainly composed of Fe, the first element group may contain Fe mixed from the magnetic powder during the reaction in addition to P and O.

ＰおよびＯ（さらにはＦｅ）からなる第１元素群と上記の第２元素とからなる本発明の絶縁皮膜は、優れた耐熱性を発現することが確認された。本発明の絶縁皮膜が優れた耐熱性を発現する理由は、現状、必ずしも明らかではないが、次のように考えることができる。
先ず、本発明者が本発明の絶縁皮膜を完成させる至った経緯を説明する。
本発明者は、最初に前述の特許文献１にあるリン酸塩被膜について調査した。このリン酸塩被膜は、Ｐ−Ｆｅ−Ｏ系の非晶質膜からなり、薄く均一であり、しかも、工業的に低コストで形成できる。このため、そのリン酸塩被膜はそれらの点で優れた絶縁皮膜である。しかし、このリン酸塩被膜を被覆した磁性粉末からなる圧粉磁心を、残留歪除去のために焼鈍（アニール）した場合、その処理温度が４００℃を越えると、急激に圧粉磁心の比抵抗が減少することが確認された。これは、本来、非晶質であったリン酸塩被膜が破壊されて結晶化し、焼結や凝集を起こして、粉末粒子間にできる空隙（３重点）に集積したためと思われる。 It was confirmed that the insulating film of the present invention consisting of the first element group consisting of P and O (and also Fe) and the second element described above exhibits excellent heat resistance. The reason why the insulating film of the present invention exhibits excellent heat resistance is not necessarily clear at present, but can be considered as follows.
First, the background of how the present inventor completed the insulating film of the present invention will be described.
The inventor first investigated the phosphate coating in Patent Document 1 described above. The phosphate coating is made of a P—Fe—O-based amorphous film, is thin and uniform, and can be formed industrially at low cost. For this reason, the phosphate coating is an insulating coating excellent in these respects. However, when the powder magnetic core made of magnetic powder coated with this phosphate coating is annealed (annealed) to remove residual strain, the specific resistance of the powder magnetic core suddenly increases when the processing temperature exceeds 400 ° C. Was confirmed to decrease. This is presumably because the phosphate film, which was originally amorphous, was destroyed and crystallized, causing sintering and aggregation, and accumulating in voids (three points) formed between the powder particles.

次に、リン酸に替えてホウリン酸（ホウ酸とリン酸）を用いて、ホウリン酸塩被膜からなる絶縁皮膜を生成し、リン酸塩被膜と同様にその耐熱性を調査した。Ｂ−Ｐ−Ｆｅ−Ｏ系の非晶質膜からなるホウリン酸塩被膜の場合も、リン酸塩被膜の場合と同様に、均一な薄膜を形成し易い点で優れるものの、やはり、４００℃程度の低温加熱で容易に結晶化し、焼結・凝集を生じて破壊されて、圧粉磁心の比抵抗が急減することが解った。
そこで、本発明者は、これらの絶縁皮膜が非晶質のガラス状皮膜であることから、ザッカライゼン則を用いて、耐熱性を向上させ得る絶縁皮膜を検討した。ザッカライゼン則は、ガラスを構成する網目形成体（網目形成イオン）と網目修飾体（網目修飾イオン）とに関する法則である。この法則に従って、その網目形成体と網目修飾体とを適切に抽出、選択すれば、耐熱性に優れる絶縁皮膜を得ることができるのではないかと考えた。 Next, using borophosphoric acid (boric acid and phosphoric acid) instead of phosphoric acid, an insulating film made of a borophosphate film was produced, and the heat resistance was investigated in the same manner as the phosphate film. In the case of a borophosphate coating made of a BP—Fe—O-based amorphous film, it is excellent in that it is easy to form a uniform thin film as in the case of a phosphate coating, but it is still about 400 ° C. It was found that the specific resistance of the powder magnetic core suddenly decreased due to crystallization by sintering at a low temperature and sintering and aggregation resulting in destruction.
Therefore, the present inventor has examined the insulating film that can improve the heat resistance using the Zacca Raisen rule because these insulating films are amorphous glassy films. The Zacca Raisen rule is a rule relating to a network forming body (network forming ion) and a network modifying body (network modifying ion) constituting the glass. It was thought that an insulating film having excellent heat resistance could be obtained by appropriately extracting and selecting the network former and the network modifier in accordance with this law.

こうして、本発明者が初めに試行錯誤の末に抽出した元素が、網目形成体を構成すると考えられるＢ、ＰおよびＯ（さらにはＦｅ）からなる第１元素群と、網目修飾体を構成すると考えられる第２元素である。この第１元素群からなる網目形成体中に、イオン半径の大きな第２元素である網目修飾体が入って構成される非晶質のガラス状絶縁皮膜は、結晶化し難く、粘度が高まって焼結・凝集を生じ難くなると考えられる。そして、その絶縁皮膜の耐熱性を実際に確認したところ、例えば、４００℃以上、さらには５００℃程度の高温まで加熱しても、十分な絶縁性が維持された。 Thus, when the inventor first extracted after trial and error constitutes a network modifier with a first element group consisting of B, P, and O (and Fe) considered to constitute a network former. It is a possible second element. An amorphous glassy insulating film composed of a network-former composed of the first element group and a network modifier that is a second element having a large ionic radius is difficult to crystallize, increases in viscosity, and burns. It is thought that it is difficult to cause flocculation / aggregation. When the heat resistance of the insulating film was actually confirmed, sufficient insulation was maintained even when heated to a high temperature of, for example, 400 ° C. or higher, or about 500 ° C.

ところが、本発明者がさらに鋭意研究したところ、上記の第１元素群中、Ｂは必ずしも必須元素とする必要がないことが判明した。すなわち、Ｂを実質的に含まない絶縁皮膜であっても、前述したＢを含む絶縁皮膜と同等の耐熱性および比抵抗を有することが確認された。従って、本発明の絶縁皮膜の場合、耐熱性や比抵抗等の特性はハイレベルでありながらも、Ｂを必ずしも必須元素としないことにより、その製造コストは一層低減されることとなった。
なお、本明細書で「Ｂを実質的に含まない」とは、コスト削減等の観点から、意図的にＢを含ませようとはしない状態をいい、Ｂの具体的な存在割合等を問題としているのではない。敢ていうなら、不可避不純物として含む場合は当然に許容される。但し、上述した内容からも解るように、Ｂは一般的な不純物ではなく、基本的に絶縁皮膜の性能を劣化させはしない。むしろ、Ｂが網目形成体を構成するように存在するときに得られる絶縁皮膜は、優れた比抵抗や耐熱性等を発揮する。 However, as a result of further intensive studies by the present inventors, it has been found that B does not necessarily have to be an essential element in the first element group. That is, it was confirmed that even an insulating film substantially free of B has the same heat resistance and specific resistance as the insulating film containing B described above. Therefore, in the case of the insulating film of the present invention, although the characteristics such as heat resistance and specific resistance are at a high level, the manufacturing cost is further reduced by not necessarily making B an essential element.
In this specification, “substantially does not contain B” means a state in which B is not intentionally included from the viewpoint of cost reduction and the like, and there is a problem with a specific existence ratio of B. It is not. Needless to say, it is naturally acceptable if it is included as an inevitable impurity. However, as can be seen from the above description, B is not a general impurity and basically does not deteriorate the performance of the insulating film. Rather, the insulating film obtained when B is present to form a network former exhibits excellent specific resistance, heat resistance, and the like.

第２元素の陽イオンを２価以上としたのは、１価の陽イオン（例えば、Ｎａ⁺、Ｋ⁺）は、水と反応し易く、長期安定性を考慮すると、存在しない方が好ましいからである。また、第２元素のイオン半径として、シャノンのイオン半径を用いたのは、それが現在最も広く用いられているからである。その中でも特に、６配位のイオン半径としたのは、配位数でイオン半径が異なるため、比較対象を明確にするためである。そして、本発明者が、種々の元素について検討したところ、第２元素のイオン半径が０．０７３ｎｍ以上である場合に、絶縁皮膜が優れた耐熱性を発現することを見いだした。逆に、イオン半径が０．０７３ｎｍ未満では、耐熱性が従来レベルであり、耐熱性の向上を図れない。なお、イオン半径は０．０７５ｎｍ以上、さらには０．０８０ｎｍ以上であるとより好ましい。また、イオン半径の上限は取扱性等を考慮して、０．１７０ｎｍ以下が好ましい。 The reason why the cation of the second element is divalent or higher is that monovalent cations (for example, Na ⁺ , K ⁺ ) are easy to react with water, and it is preferable that they do not exist in consideration of long-term stability. It is. The reason why Shannon's ionic radius is used as the ionic radius of the second element is that it is currently most widely used. Among them, the reason why the six-coordinate ionic radius is used is that the ionic radius differs depending on the number of coordination, and thus the comparison target is clarified. And when this inventor examined various elements, when the ionic radius of the 2nd element was 0.073 nm or more, it discovered that an insulating film expressed the outstanding heat resistance. On the contrary, if the ion radius is less than 0.073 nm, the heat resistance is at the conventional level, and the heat resistance cannot be improved. The ionic radius is more preferably 0.075 nm or more, and further preferably 0.080 nm or more. In addition, the upper limit of the ion radius is preferably 0.170 nm or less in consideration of handleability and the like.

このような第２元素として、具体的には、例えば、アルカリ土類金属元素や希土類元素等を挙げることができる。アルカリ土類金属元素には、ベリリウム（Ｂｅ）、Ｍｇ、Ｃａ、Ｓｒ、バリウム（Ｂａ）、ラジウム（Ｒａ）があるが、ＢｅおよびＭｇは、６配位のイオン半径が０．０７３ｎｍ未満であり、除かれる。取扱性、安全性、好環境性等を考慮すると、アルカリ土類金属元素から第２元素としては、ＣａまたはＳｒが好ましい。また、希土類元素には、スカンジウム（Ｓｃ）、Ｙ、ランタノイド元素、アクチノイド元素があるが、同様に、取扱性等を考慮して、Ｙが好ましい。その他、第２元素となり得る元素として、ランタノイド（Ｌａ〜Ｌｕ）、ビスマス（Ｂｉ）を挙げることができる。これらの各元素のイオン半径を価数と共に表１に参考として示した。
なお、これらの第２元素は、１種の元素のみならず、複数種の元素であっても良いことはいうまでもない。 Specific examples of such second elements include alkaline earth metal elements and rare earth elements. Alkaline earth metal elements include beryllium (Be), Mg, Ca, Sr, barium (Ba), and radium (Ra), but Be and Mg have a six-coordinate ion radius of less than 0.073 nm. , Excluded. In consideration of handleability, safety, environmental friendliness, etc., Ca or Sr is preferable as the second element from the alkaline earth metal element. The rare earth elements include scandium (Sc), Y, lanthanoid elements, and actinoid elements. Similarly, Y is preferable in consideration of handling properties and the like. Other elements that can be the second element include lanthanoids (La to Lu) and bismuth (Bi). The ionic radii of each of these elements are shown in Table 1 together with the valence for reference.
Needless to say, these second elements may be not only one kind of element but also a plurality of kinds of elements.

本発明の絶縁皮膜が耐熱性に優れることは上述した通りであるが、その耐熱性を定量的に評価することは必ずしも容易ではない。例えば、Ｆｅを主成分とする磁性粉末の表面に被覆した本発明の絶縁皮膜の場合、４５０℃以上の耐熱性を有するが、そのことは必ずしも、全ての絶縁皮膜が全く破壊されないことを意味しない。ここで重要なことは、従来の絶縁皮膜なら、ほとんどの絶縁皮膜が破壊されて比抵抗が急減していたような高温域でさえ、本発明の絶縁皮膜によると、その絶縁皮膜の破壊が抑制されて、比抵抗が急減しないことである。従って、仮に圧粉磁心の焼鈍によってその比抵抗が多少低下し渦電流損失が増加したとしても、その一方で、残留歪が減少しヒステリシス損失が減少して、全体として高周波損失が低減されれば、本発明の絶縁皮膜には十分なメリットが存在することになる。これらを踏まえて、本発明でいう「耐熱温度」とは、絶縁皮膜の比抵抗が急減しない温度とする。 As described above, the insulating film of the present invention is excellent in heat resistance, but it is not always easy to quantitatively evaluate the heat resistance. For example, the insulating film of the present invention coated on the surface of a magnetic powder containing Fe as a main component has a heat resistance of 450 ° C. or higher, but this does not necessarily mean that all the insulating films are not destroyed at all. . What is important here is that with the conventional insulation film, the insulation film of the present invention suppresses the destruction of the insulation film even in the high temperature range where most of the insulation film was destroyed and the specific resistance suddenly decreased. That is, the specific resistance does not decrease rapidly. Therefore, even if the specific resistance decreases somewhat due to the annealing of the dust core and the eddy current loss increases, on the other hand, if the residual strain decreases, the hysteresis loss decreases, and the high frequency loss is reduced as a whole. The insulating film of the present invention has sufficient merit. Based on these, the “heat-resistant temperature” in the present invention is a temperature at which the specific resistance of the insulating film does not decrease rapidly.

もっとも、本発明の絶縁皮膜は、耐熱温度が高いため、従来の焼鈍熱処理（例えば、焼鈍温度が４００℃以下）なら、十分な耐熱余裕を有する。従って、その程度の焼鈍ならば、本発明の絶縁皮膜によって、残留歪の除去と大きな比抵抗の安定的確保とが十分に両立され得る。
さらに焼鈍等の熱処理を行わない場合でも、高温環境下で使用される電磁機器の圧粉磁心等に本発明の絶縁皮膜を利用すれば、その電磁機器も耐熱性に優れたものとなり、高温域でも安定した性能を発揮し得る。
本発明の絶縁皮膜は、上述したように、例えば、圧粉磁心を構成する磁性粉末の表面を被覆する場合に使用されると特に有効であるが、その場合には限られない。例えば、本発明の絶縁皮膜は、板状の磁性材料（薄いケイ素鋼板等）の表面を被覆するために使用しても良い。また、磁性材料の被覆に限らず、絶縁性を要する部材の表面に被覆しても良い。特に、高温域での絶縁性が要求される部材の表面に、本発明の絶縁皮膜を被覆すると好適である。 However, since the insulating film of the present invention has a high heat-resistant temperature, it has a sufficient heat-resistance margin if it is a conventional annealing heat treatment (for example, the annealing temperature is 400 ° C. or lower). Therefore, if annealing is performed to such an extent, removal of residual strain and stable securing of a large specific resistance can be sufficiently achieved by the insulating film of the present invention.
Furthermore, even when heat treatment such as annealing is not performed, if the insulating film of the present invention is used for a dust core of an electromagnetic device used in a high temperature environment, the electromagnetic device is also excellent in heat resistance and is in a high temperature range. But it can show stable performance.
As described above, the insulating film of the present invention is particularly effective when used, for example, when coating the surface of the magnetic powder constituting the dust core, but is not limited thereto. For example, the insulating film of the present invention may be used to coat the surface of a plate-like magnetic material (such as a thin silicon steel plate). In addition, the surface of a member that requires insulation is not limited to the coating of the magnetic material. In particular, it is preferable to cover the surface of a member that requires insulation in a high temperature region with the insulating film of the present invention.

（絶縁皮膜の製造方法）
このように耐熱性に優れた絶縁皮膜は、例えば、次のような本発明の製造方法によって得られる。
すなわち、本発明の絶縁皮膜の製造方法は、シャノンにより定義された６配位のイオン半径が０．０７３ｎｍ以上である２価以上の陽イオンを生じ得る元素の化合物および／または塩とリン酸とを混合して溶液とした被覆処理液に、被覆される相手材を接触させる接触工程と、該接触工程後の相手材を乾燥させる乾燥工程とからなり、該相手材の表面に絶縁皮膜を形成させることを特徴とする。 (Insulating film manufacturing method)
Thus, the insulating film excellent in heat resistance is obtained, for example, by the following production method of the present invention.
That is, the method for producing an insulating film of the present invention comprises a compound and / or salt of an element capable of producing a divalent or higher cation having a hexacoordinate ion radius defined by Shannon of 0.073 nm or more, and phosphoric acid. A contact process in which the other material to be coated is brought into contact with the coating treatment liquid mixed into the solution and a drying process in which the other material after the contact process is dried, and an insulating film is formed on the surface of the other material It is characterized by making it.

（磁心用粉末）
その絶縁皮膜を磁性粉末の表面に被覆すれば、圧粉磁心の製造に好適な磁心用粉末が得られる。
従って、本発明は、磁性粉末と、該磁性粉末の表面に被覆された、ＰとＯと（さらにはＦｅと）からなる第１元素群とシャノンにより定義された６配位のイオン半径が０．０７３ｎｍ以上である２価以上の陽イオンを生じ得る第２元素とを必須構成元素としＢを実質的に含まない絶縁皮膜と、からなることを特徴とする磁心用粉末とすることもできる。 (Powder for magnetic core)
If the insulating film is coated on the surface of the magnetic powder, a magnetic core powder suitable for manufacturing a dust core can be obtained.
Therefore, according to the present invention, the 6-coordinate ion radius defined by Shannon and the first element group consisting of magnetic powder, P, O (and Fe) coated on the surface of the magnetic powder is 0. It is also possible to obtain a magnetic core powder characterized by comprising an insulating film that contains a second element capable of producing a divalent or higher cation of 0.03 nm or more as an essential constituent element and does not substantially contain B.

（磁心用粉末の製造方法）
この磁心用粉末は、例えば、次のような本発明の製造方法によって得られる。
すなわち、本発明の磁心用粉末の製造方法は、シャノンにより定義された６配位のイオン半径が０．０７３ｎｍ以上である２価以上の陽イオンを生じ得る元素の化合物および／または塩とリン酸とを混合して溶液とした被覆処理液に磁性粉末を接触させる接触工程と、該接触工程後の磁性粉末を加熱し乾燥させる乾燥工程とからなり、該磁性粉末の表面に絶縁皮膜を形成させることを特徴とする。 (Method for producing magnetic core powder)
This magnetic core powder is obtained, for example, by the following production method of the present invention.
That is, the method for producing a powder for a magnetic core according to the present invention comprises a compound and / or salt of an element capable of producing a divalent or higher cation having a hexacoordinate ion radius defined by Shannon of 0.073 nm or more and phosphoric acid. A contact process in which the magnetic powder is brought into contact with the coating treatment liquid obtained by mixing the magnetic powder and a drying process in which the magnetic powder after the contact process is heated and dried, and an insulating film is formed on the surface of the magnetic powder. It is characterized by that.

（圧粉磁心）
さらに、その磁心用粉末を加圧成形すれば、耐熱性に優れた圧粉磁心が得られる。
従って、本発明は、ＰとＯと（さらにはＦｅと）からなる第１元素群とシャノンにより定義された６配位のイオン半径が０．０７３ｎｍ以上である２価以上の陽イオンを生じ得る第２元素とを必須構成元素としＢを実質的に含まない絶縁皮膜が磁性粉末の表面に被覆されてなる磁心用粉末を、加圧成形してなることを特徴とする圧粉磁心とすることもできる。 (Dust core)
Further, if the magnetic core powder is pressure-molded, a powder magnetic core having excellent heat resistance can be obtained.
Accordingly, the present invention can generate a divalent or higher cation having a six-coordinate ionic radius defined by Shannon and a first element group consisting of P, O, and (and further Fe) of 0.073 nm or more. A powder magnetic core characterized in that a powder for a magnetic core formed by pressing a surface of a magnetic powder with an insulating film containing the second element as an essential constituent element and substantially free of B is formed on the surface of the magnetic powder. You can also.

（圧粉磁心の製造方法）
そして、この圧粉磁心は、例えば、次のような本発明の製造方法によって得られる。
すなわち、本発明の圧粉磁心の製造方法は、ＰとＯと（さらにはＦｅと）からなる第１元素群とシャノンにより定義された６配位のイオン半径が０．０７３ｎｍ以上である２価以上の陽イオンを生じ得る第２元素とを必須構成元素としＢを実質的に含まない絶縁皮膜が磁性粉末の表面に被覆されてなる磁心用粉末を成形用金型に充填する充填工程と、該成形用金型内の磁心用粉末を加圧成形する成形工程と、からなることを特徴とする。 (Production method of dust core)
And this powder magnetic core is obtained by the manufacturing method of the present invention as follows, for example.
That is, the method for producing a dust core according to the present invention is a divalent alloy in which the 6-coordinate ionic radius defined by Shannon and the first element group consisting of P, O (and Fe) is 0.073 nm or more. A filling step in which a molding die is filled with a magnetic core powder in which an insulating film substantially free of B, which is an essential constituent element and the second element capable of generating the above cation, is coated on the surface of the magnetic powder; A molding step of pressure-molding the magnetic core powder in the molding die.

なお、本願明細書でいう磁性材料や磁性粉末は、８属遷移元素（Ｆｅ、Ｃｏ、Ｎｉ等）等の強磁性元素を主成分とするものである。中でも、取扱性、入手性、コスト等から、Ｆｅを主成分とするものが好ましい。さらには、高純度（純度９９．７％以上）のＦｅ粉が磁性粉末として好ましい。 Note that the magnetic material and magnetic powder referred to in the present specification are mainly composed of a ferromagnetic element such as a group 8 transition element (Fe, Co, Ni, etc.). Among these, those containing Fe as a main component are preferable from the viewpoint of handleability, availability and cost. Furthermore, high purity (purity 99.7% or more) Fe powder is preferable as the magnetic powder.

発明の実施形態を挙げて、本発明をより詳しく説明する。なお、以下の実施形態を含め、本明細書で説明する内容は、本発明に係る絶縁皮膜のみならず、磁心用粉末、圧粉磁心およびそれらの製造方法に、適宜、適用できるものであることを断っておく。また、いずれの実施形態が最良であるか否かは、対象、要求性能等によって異なることを断っておく。 The present invention will be described in more detail with reference to embodiments of the invention. In addition, the contents described in this specification including the following embodiments are applicable not only to the insulating film according to the present invention, but also to the magnetic core powder, the dust core, and the manufacturing method thereof as appropriate. I refuse. It should be noted that which embodiment is best depends on the target, required performance, and the like.

（１）絶縁皮膜
本発明の絶縁皮膜は、前述したように、ＰおよびＯ（さらにはＦｅ）の第１元素群と、イオン半径が大きなＣａ等の第２元素とを必須構成元素とするものである。このＰおよびＯが網目形成体元素であり、Ｃａ等が網目修飾体元素であって、それらによってガラス状絶縁皮膜が形成されていると考えられる。
勿論、これらの元素は必須構成元素であって、絶縁皮膜がそれ以外の元素を含有していても良い。特に、製造方法にもよるが、絶縁皮膜が被覆される相手材の元素（Ｆｅ等）を含むことは十分考えられる。同様に、結果的にＢを含んでも良い。 (1) Insulating film As described above, the insulating film of the present invention comprises the first element group of P and O (and also Fe) and the second element such as Ca having a large ionic radius as essential constituent elements. It is. It is considered that P and O are network former elements, Ca and the like are network modifier elements, and a glassy insulating film is formed by them.
Of course, these elements are essential constituent elements, and the insulating film may contain other elements. In particular, although depending on the manufacturing method, it is sufficiently conceivable to include an element (Fe or the like) of the counterpart material to be coated with the insulating film. Similarly, B may be included as a result.

絶縁皮膜は、膜厚が厚いほど抵抗が大きくなる。しかし、圧粉磁心用の磁性粉末を被覆するような場合、膜厚があまり厚いと、成形された圧粉磁心の磁束密度が低下する。そこで、圧粉磁心の磁束密度と比抵抗とを確保する観点から、膜厚は、１０〜１００ｎｍ、さらには、１０〜５０ｎｍであると好ましい。 As the film thickness increases, the resistance of the insulating film increases. However, when the magnetic powder for the dust core is coated, if the film thickness is too thick, the magnetic flux density of the molded dust core is lowered. Therefore, from the viewpoint of ensuring the magnetic flux density and specific resistance of the dust core, the film thickness is preferably 10 to 100 nm, and more preferably 10 to 50 nm.

（２）磁心用粉末
磁心用粉末は、磁性粉末の表面に本発明の絶縁皮膜を被覆したものであり、主に、圧粉磁心の製造に用いられる。
磁心用粉末の原料粉末である磁性粉末は、強磁性元素を主成分とするものが好ましく、コスト、入手性等から、Ｆｅ粉末が一般的である。特に、純度が９９．５％以上、さらには９９．８％以上の純鉄粉が好適である。このような鉄粉として、例えばヘガネス社製のＡＢＣ１００．３０を用いることができる。この鉄粉は、Ｆｅ以外の成分がＣ：０．００１、Ｍｎ：０．０２、Ｏ：０．０８（単位：質量％）以下であり、その他の市販鉄粉に比べて不純物が極めて少ない。しかも、その純鉄粉は圧縮性に優れるため、圧粉磁心の製造に適している。 (2) Magnetic core powder The magnetic core powder is obtained by coating the surface of the magnetic powder with the insulating film of the present invention, and is mainly used for the production of a dust core.
The magnetic powder that is a raw material powder for the magnetic core powder is preferably composed mainly of a ferromagnetic element, and Fe powder is generally used from the viewpoint of cost, availability, and the like. In particular, pure iron powder having a purity of 99.5% or more, more preferably 99.8% or more is suitable. As such iron powder, for example, ABC100.30 manufactured by Höganäs can be used. In this iron powder, components other than Fe are C: 0.001, Mn: 0.02, O: 0.08 (unit: mass%) or less, and there are very few impurities compared to other commercially available iron powders. Moreover, since the pure iron powder is excellent in compressibility, it is suitable for manufacturing a dust core.

この他、磁性粉末は、純鉄以外に、コバルト（Ｃｏ）、ニッケル（Ｎｉ）等の強磁性元素を含有しても良い。例えば、磁性粉末全体を１００質量％としたときに、Ｃｏを５〜３０質量％含むと、磁束密度の向上を図れるので好ましい。この他、ＳｉやＡｌを０．３〜４質量％程度含んでも良い。勿論、磁気的特性を低下させる不純物元素は少ない程よい。 In addition, the magnetic powder may contain ferromagnetic elements such as cobalt (Co) and nickel (Ni) in addition to pure iron. For example, when the total amount of magnetic powder is 100% by mass, it is preferable to include 5-30% by mass of Co since the magnetic flux density can be improved. In addition, Si or Al may be included in an amount of about 0.3 to 4% by mass. Of course, the smaller the number of impurity elements that degrade the magnetic properties, the better.

また、磁性粉末は、複数の粉末を混合した混合粉末でも良い。例えば、純鉄粉とＦｅ−４９Ｃｏ−２Ｖ（パーメンジュール）粉、純鉄粉とＦｅ−３Ｓｉ粉、センダスト（Ｆｅ−９Ｓｉ−６Ａｌ）粉と純鉄粉等の混合粉末であっても良い。
圧粉磁心の高密度化のためには、磁心用粉末の粒径が２０〜３００μｍ、さらには５０〜２００μｍであると好適である。本発明者が試験したところ、渦電流損失の低減を図る観点からは、その粒径が細かい程好ましく、例えば、５０μｍ以下とすると良い。一方、ヒステリシス損失の低減を図る観点からは、粒径を粗くする方が好ましく、例えば、１００μｍ以上とすると良い。なお、磁心用粉末の分級は、篩い分法等により容易に行える。 The magnetic powder may be a mixed powder obtained by mixing a plurality of powders. For example, a mixed powder of pure iron powder and Fe-49Co-2V (permendur) powder, pure iron powder and Fe-3Si powder, sendust (Fe-9Si-6Al) powder and pure iron powder, or the like may be used.
In order to increase the density of the dust core, the particle diameter of the magnetic core powder is preferably 20 to 300 μm, more preferably 50 to 200 μm. As a result of testing by the present inventor, from the viewpoint of reducing eddy current loss, the smaller the particle size, the better, for example, 50 μm or less. On the other hand, from the viewpoint of reducing the hysteresis loss, it is preferable to make the particle diameter coarser, for example, 100 μm or more. Note that the magnetic core powder can be easily classified by a sieving method or the like.

（３）圧粉磁心
本発明の圧粉磁心は、上記磁心用粉末を加圧成形したものである。圧粉磁心の構成粒子が本発明の絶縁皮膜で被覆されている限り、磁気的特性等は問わない。もっとも、本発明の絶縁皮膜によって構成粒子が被覆されているため、高温域まで安定した電気的特性（比抵抗）が確保される。さらに、後述する温間高圧成形を用いると、その磁気的特性さえも、非常に優れた圧粉磁心が容易に得られる。 (3) Powder magnetic core The powder magnetic core of the present invention is obtained by press-molding the magnetic core powder. As long as the constituent particles of the dust core are covered with the insulating film of the present invention, the magnetic properties and the like are not limited. However, since the constituent particles are covered with the insulating film of the present invention, stable electrical characteristics (specific resistance) are ensured up to a high temperature range. Furthermore, if warm high pressure molding described later is used, a very excellent dust core can be easily obtained even with its magnetic properties.

次に、この圧粉磁心の電気的特性、磁気的特性、機械的特性等について説明する。
圧粉磁心の電気的特性を指標する代表的なものは、比抵抗である。比抵抗は、形状に依存しない圧粉磁心ごとの固有値であり、同形状の圧粉磁心であれば比抵抗が大きいほど、渦電流損失は小さくなる。 Next, electrical characteristics, magnetic characteristics, mechanical characteristics, etc. of the dust core will be described.
A typical index for indicating the electrical characteristics of the dust core is a specific resistance. The specific resistance is an eigenvalue for each dust core that does not depend on the shape. For a dust core having the same shape, the larger the specific resistance, the smaller the eddy current loss.

本発明の圧粉磁心の場合、その比抵抗が高温域まで安定しているのみならず、その値自体も大きい。例えば、圧粉磁心の成形後に焼鈍を行わない場合、その比抵抗は、３０μΩｍ以上、さらには、１０００μΩｍ以上ともなる。焼鈍を行う場合でも、焼鈍温度が４００℃程度なら、比抵抗は１０μΩｍ以上、さらには、２０μΩｍ以上ともなる。また、焼鈍温度が４５０〜５００℃程度となっても、５μΩｍ以上、さらには、１０μΩｍ以上の比抵抗が確保される。 In the case of the dust core of the present invention, the specific resistance is not only stable to a high temperature range, but also the value itself is large. For example, when annealing is not performed after molding of the dust core, the specific resistance is 30 μΩm or more, and further 1000 μΩm or more. Even when annealing is performed, if the annealing temperature is about 400 ° C., the specific resistance is 10 μΩm or more, and further 20 μΩm or more. Further, even when the annealing temperature is about 450 to 500 ° C., a specific resistance of 5 μΩm or more, further 10 μΩm or more is ensured.

圧粉磁心の磁気的特性を指標する代表的なものは、本来、透磁率かもしれないが、透磁率は、一般的なＢ−Ｈ曲線からも解るように一定ではない。そこで、その代替として、特定強さの磁界中においたときにできる磁束密度で圧粉磁心の磁気的特性を特定することにする。
その特定磁界の一例として、低磁場（２ｋＡ／ｍ）と高磁場（１０ｋＡ／ｍ）とを選択し、それらの磁界中に圧粉磁心を置いたときにできる磁束密度Ｂ_2k、Ｂ_10kで本発明の圧粉磁心を評価した。本発明の圧粉磁心の場合、２ｋＡ／ｍの低磁場中でも十分大きな磁束密度Ｂ_2k≧１．１Ｔさらに１．２Ｔを得ることができる。また、１０ｋＡ／ｍの高磁場中でも十分大きな磁束密度Ｂ_10k≧１．６Ｔさらには１．７Ｔが得られる。
なお、飽和磁化Ｍｓが小さいと、高磁場中で大きな磁束密度が得られないが、本発明の圧粉磁心では、例えば、１．６ＭＡ／ｍの磁場中における飽和磁化Ｍｓ≧１．９Ｔさらには１．９５Ｔ以上ともなり、高磁界中でも安定した高磁束密度が得られる。 A typical index for indicating the magnetic characteristics of the dust core may be magnetic permeability, but the magnetic permeability is not constant as can be seen from a general BH curve. Therefore, as an alternative, the magnetic characteristics of the dust core are specified by the magnetic flux density that is generated when the magnetic field is placed in a magnetic field having a specific strength.
As an example of the specific magnetic field, a low magnetic field (2 kA / m) and a high magnetic field (10 kA / m) are selected, and magnetic flux densities B _2k and B _10k generated when a dust core is placed in these magnetic fields The dust core of the invention was evaluated. In the case of the dust core of the present invention, a sufficiently large magnetic flux density B _2k ≧ 1.1T and 1.2T can be obtained even in a low magnetic field of 2 kA / m. In addition, a sufficiently large magnetic flux density B _10k ≧ 1.6T or 1.7T can be obtained even in a high magnetic field of 10 kA / m.
Note that if the saturation magnetization Ms is small, a large magnetic flux density cannot be obtained in a high magnetic field. However, in the dust core of the present invention, for example, the saturation magnetization Ms ≧ 1.9T in a 1.6 MA / m magnetic field. 1.95 T or more, and a stable high magnetic flux density can be obtained even in a high magnetic field.

さらに、圧粉磁心の磁気的特性を指標するものとして、保磁力がある。圧粉磁心の場合、保磁力が小さい程、交流磁界に対する追従性が良く、ヒステリシス損失も小さくなる。この保磁力は、前述したように、残留歪を除去することで低減できる。本発明の絶縁皮膜の優れた耐熱性を利用して、高温焼鈍を行うと、例えば、保磁力ｂＨｃが３２０Ａ／ｍ以下、３００Ａ／ｍ以下、さらには２９０Ａ／ｍ以下ともなり得る。なお、本明細書中でいう保磁力ｂＨｃは、最大磁場２ｋＡ／ｍでの磁化曲線から測定した値と定義する。 Furthermore, there is a coercive force as an index of the magnetic characteristics of the dust core. In the case of a dust core, the smaller the coercive force, the better the followability to an alternating magnetic field and the smaller the hysteresis loss. As described above, the coercive force can be reduced by removing the residual strain. When high temperature annealing is performed using the excellent heat resistance of the insulating film of the present invention, for example, the coercive force bHc can be 320 A / m or less, 300 A / m or less, and even 290 A / m or less. The coercive force bHc in this specification is defined as a value measured from a magnetization curve at a maximum magnetic field of 2 kA / m.

圧粉磁心の機械的特性を指標する代表的なものとして強度がある。圧粉磁心は、鋳造品や焼結品とは異なり、絶縁皮膜で被覆された構成粒子の塑性変形によって、主に機械的に結合されている。このため、本来、その強度は弱い。しかし、後述の温間高圧成形により、本発明の圧粉磁心は、その用途を拡大するに足る十分な強度を得ている。
特に、本発明の絶縁皮膜で被覆された磁性粉末は、それが球状のガスアトマイズ粉からなる場合でも、その絶縁皮膜同士の絡みや吸引力等が作用して、圧粉磁心の各構成粒子は強固に結合される。そのため、強度にも優れた粉末成形体（圧粉磁心）が得られる。例えば、４点曲げ強度σが５０ＭＰａ以上、さらには１００ＭＰａ以上という高強度が得られる。なお、４点曲げ強度σは、ＪＩＳに規定されていないが、圧粉体の試験方法により求めることができる。 Strength is a representative index for the mechanical properties of a dust core. Unlike a cast product or a sintered product, the dust core is mainly mechanically coupled by plastic deformation of constituent particles covered with an insulating film. For this reason, its strength is inherently weak. However, the powder magnetic core of the present invention has obtained sufficient strength to expand its application by warm high pressure molding described later.
In particular, even when the magnetic powder coated with the insulating film of the present invention is composed of a spherical gas atomized powder, the entanglement or attractive force of the insulating film acts, and each constituent particle of the powder magnetic core is strong. Combined with Therefore, a powder molded body (powder magnetic core) excellent in strength can be obtained. For example, a high strength such that the four-point bending strength σ is 50 MPa or more, and further 100 MPa or more is obtained. The four-point bending strength σ is not defined in JIS, but can be determined by a green compact test method.

（４）絶縁皮膜の製造方法または磁心用粉末の製造方法
絶縁皮膜の製造方法も磁心用粉末の製造方法も、相手材（磁性粉末）と被覆処理液との接触工程と、その後の乾燥工程とから基本的になる。なお、絶縁皮膜の相手材は磁性粉末に限らないが、以下では、相手材が磁性粉末である場合を適宜例示した。 (4) Manufacturing method of insulating film or manufacturing method of magnetic core powder Both the manufacturing method of the insulating film and the manufacturing method of the magnetic core powder include a contact process between the counterpart material (magnetic powder) and the coating treatment liquid, and a subsequent drying process. Basically from. In addition, although the other material of an insulating film is not restricted to magnetic powder, the case where the other material was magnetic powder was illustrated suitably below.

（ａ）被覆処理液は、リン酸および本発明でいう第２元素とを含む溶液である。これは、水溶液には限らず、エタノール、メタノール、イソプロピルアルコール、アセトン、グリセリン等の有機溶媒を用いた溶液でも良い。いずれにしても、被覆処理液は、それらの溶媒中にリン酸を混合し、アルカリ土類金属元素や希土類元素の化合物や塩を溶解させてなる。
さらに、後述の接触工程を改善するために、磁性粉末（例えば、Ｆｅ粉）との濡れ性を向上させて均一な被膜を形成させるための界面活性剤、磁性粉末（例えば、Ｆｅ粉）の酸化を防止するための防錆剤等を添加しても良い。 (A) The coating treatment liquid is a solution containing phosphoric acid and the second element referred to in the present invention. This is not limited to an aqueous solution, but may be a solution using an organic solvent such as ethanol, methanol, isopropyl alcohol, acetone, glycerin or the like. In any case, the coating treatment liquid is prepared by mixing phosphoric acid in these solvents and dissolving an alkaline earth metal element or rare earth element compound or salt.
Furthermore, in order to improve the contact process described later, a surfactant for improving wettability with magnetic powder (for example, Fe powder) to form a uniform film, oxidation of magnetic powder (for example, Fe powder) A rust preventive agent or the like may be added.

（ｂ）接触工程は、例えば、被覆処理液を相手材に噴霧する溶液噴霧法（噴霧工程）、被覆処理液中に浸漬する溶液浸漬法（浸漬工程）等、種々の方法（工程）により行える。溶液噴霧法、溶液浸漬法は大量処理が可能であり、工業的にも有効な方法である。
また、これらの方法に限らず、めっきの如く、電気化学的反応を利用して、相手材の表面に薄く均一な絶縁皮膜を形成しても良い。この場合、絶縁皮膜によって被覆された相手材の表面は、電気的に絶縁されるため、被覆されていない表面部分（露出している部分）が、自然に、優先的に被覆処理液と反応していくことになる。その結果、相手材（磁性粉末）の表面が順次コーティングされ、相手材の全面がピンホールなく均一に被覆されることとなる。 (B) The contact step can be performed by various methods (steps) such as a solution spraying method (spraying step) in which a coating treatment liquid is sprayed on a counterpart material and a solution immersion method (immersion step) in which the coating treatment solution is immersed in the coating treatment solution. . The solution spraying method and the solution dipping method can be processed in large quantities, and are industrially effective methods.
Further, not limited to these methods, a thin and uniform insulating film may be formed on the surface of the counterpart material by utilizing an electrochemical reaction such as plating. In this case, since the surface of the counterpart material coated with the insulating film is electrically insulated, the uncovered surface portion (exposed portion) naturally and preferentially reacts with the coating treatment liquid. It will follow. As a result, the surface of the counterpart material (magnetic powder) is sequentially coated, and the entire surface of the counterpart material is uniformly coated without pinholes.

さらに、この接触工程で用いる被覆処理液の濃度を変更することにより、形成される絶縁皮膜の膜厚を調整することも可能である。被覆処理液の濃度を濃くすると、膜厚の厚い絶縁皮膜が得られ、薄くすると、膜厚の薄い絶縁皮膜が得られる。勿論、薄い膜厚を重ねて形成し、全体的に厚い絶縁皮膜としても良い。
また、相手材と被覆処理液との接触時間も、その膜厚に影響するとも考えられる。しかし、現実には、両者の反応時間が短いこともあり、一旦、相手材の表面が被覆されると、接触時間を長くしても、膜厚の変化は少ない。 Furthermore, it is also possible to adjust the film thickness of the insulating film to be formed by changing the concentration of the coating treatment liquid used in this contact step. When the concentration of the coating treatment liquid is increased, a thick insulating film is obtained, and when the concentration is reduced, a thin insulating film is obtained. Of course, it is possible to form thin insulating films as a whole by forming thin film thicknesses.
Further, the contact time between the counterpart material and the coating treatment liquid may also affect the film thickness. However, in reality, the reaction time of both may be short, and once the surface of the counterpart material is coated, the change in film thickness is small even if the contact time is increased.

（ｃ）乾燥工程は、相手材に付着した余分な被覆処理液やその溶媒を発散させる行程である。この乾燥工程は、加熱乾燥は勿論、自然乾燥でも良い。もっとも、相手材の表面に絶縁皮膜を安定的に、素早く定着させるためには、加熱乾燥（加熱乾燥工程）が好ましい。加熱温度は、８０〜３５０℃程度、加熱時間は、１０〜１８０ｍｉｎ程度が好ましい。なお、加熱雰囲気は、真空脱気中や窒素中でも良いが、大気中で十分である。 (C) The drying step is a step of diverging excess coating treatment liquid and its solvent adhering to the counterpart material. This drying step may be natural drying as well as heat drying. However, in order to stably and quickly fix the insulating film on the surface of the counterpart material, heat drying (heat drying step) is preferable. The heating temperature is preferably about 80 to 350 ° C., and the heating time is preferably about 10 to 180 minutes. The heating atmosphere may be vacuum degassing or nitrogen, but is sufficient in the air.

（５）圧粉磁心の製造方法
圧粉磁心の製造方法は、上述の磁心用粉末を成形用金型に充填する充填工程と、充填された磁心用粉末を加圧成形する成形工程とから基本的になる。圧粉磁心の磁気的特性を向上させる上で重要なのは成形工程である。特に、その成形圧力が、圧粉磁心の高密度化、およびそれに伴う圧粉磁心の高磁束密度化等の観点から非常に重要となる。
もっとも、その成形圧力を大きくすると、成形用金型の内面と磁心用粉末との間でかじりを生じたり、抜圧が過大となったり、金型寿命を極端に低下させたりし易い。このため、従来の成形方法では、その成形圧力を大きくすることが現実には困難であった。 (5) Manufacturing method of dust core The manufacturing method of the dust core is basically composed of a filling step of filling the above-described magnetic core powder into a molding die and a molding step of press-molding the filled magnetic core powder. Become. In order to improve the magnetic properties of the dust core, the molding process is important. In particular, the molding pressure is very important from the viewpoint of increasing the density of the dust core and increasing the magnetic flux density of the dust core.
However, when the molding pressure is increased, galling is likely to occur between the inner surface of the molding die and the magnetic core powder, the pressure is excessively increased, and the die life is extremely reduced. For this reason, in the conventional molding method, it was actually difficult to increase the molding pressure.

しかし、本発明者は、前述したように、画期的な温間高圧成形法を確立し、それらの課題を解決済である。この温間高圧成形法は、前記充填工程を高級脂肪酸系潤滑剤を内面に塗布した成形用金型へ磁心用粉末を充填する工程とし、前記成形工程をその磁心用粉末と成形用金型の内面との間に金属石鹸皮膜が生成される温間高圧成形工程とするものである。
一例を挙げると、磁性粉末をＦｅを主成分とする粉末とし、高級脂肪酸系潤滑剤をステアリン酸リチウムとした場合、成形用金型の内面に接する圧粉磁心の外表面には、潤滑性に優れたステアリン酸鉄からなる金属石鹸皮膜が形成される。このステアリン酸鉄皮膜の存在によって、かじり等が生じず、また、非常に低い抜圧で圧粉磁心が成形用金型から取出される。そして、金型の長寿命化も図れる。 However, as described above, the present inventor has established an epoch-making warm high-pressure molding method and has solved these problems. In this warm high-pressure molding method, the filling step is a step of filling a molding die coated with a higher fatty acid-based lubricant with a magnetic core powder, and the molding step is performed between the magnetic core powder and the molding die. This is a warm high pressure forming process in which a metal soap film is formed between the inner surface and the inner surface.
For example, when the magnetic powder is a powder containing Fe as a main component and the higher fatty acid-based lubricant is lithium stearate, the outer surface of the powder magnetic core in contact with the inner surface of the molding die is lubricated. A metal soap film made of excellent iron stearate is formed. The presence of the iron stearate film does not cause galling or the like, and the dust core is taken out from the molding die with a very low pressure. In addition, the life of the mold can be extended.

次に、この製造方法をさらに詳細に説明する。
（ａ）充填工程
充填工程に際して、成形用金型の内面に高級脂肪酸系潤滑剤を塗布する必要がある（塗布工程）。
塗布する高級脂肪酸系潤滑剤としては、高級脂肪酸自体の他、高級脂肪酸の金属塩であると好適である。高級脂肪酸の金属塩には、リチウム塩、カルシウム塩又は亜鉛塩等がある。特に、ステアリン酸リチウム、ステアリン酸カルシウム、ステアリン酸亜鉛が好ましい。この他、ステアリン酸バリウム、パルミチン酸リチウム、オレイン酸リチウム、パルミチン酸カルシウム、オレイン酸カルシウム等を用いることもできる。 Next, this manufacturing method will be described in more detail.
(A) Filling step In the filling step, it is necessary to apply a higher fatty acid-based lubricant to the inner surface of the molding die (application step).
The higher fatty acid lubricant to be applied is preferably a metal salt of a higher fatty acid in addition to the higher fatty acid itself. Examples of the higher fatty acid metal salts include lithium salts, calcium salts, and zinc salts. In particular, lithium stearate, calcium stearate, and zinc stearate are preferable. In addition, barium stearate, lithium palmitate, lithium oleate, calcium palmitate, calcium oleate, and the like can also be used.

この塗布工程は、加熱された成形用金型内に水または水溶液に分散させた高級脂肪酸系潤滑剤を噴霧する工程であると、好適である。
高級脂肪酸系潤滑剤が水等に分散していると、成形用金型の内面へ高級脂肪酸系潤滑剤を均一に噴霧することが容易となる。さらに、加熱された成形用金型内にそれを噴霧すると、水分が素早く蒸発して、成形用金型の内面へ高級脂肪酸系潤滑剤を均一に付着させることができる。そのときの成形用金型の加熱温度は、後述の成形工程の温度を考慮する必要があるが、例えば、１００℃以上に加熱しておけば足る。もっとも、高級脂肪酸系潤滑剤の均一な膜を形成するために、その加熱温度を高級脂肪酸系潤滑剤の融点未満にすることが好ましい。例えば、高級脂肪酸系潤滑剤としてステアリン酸リチウムを用いた場合、その加熱温度を２２０℃未満とすると良い。 This coating step is preferably a step of spraying a higher fatty acid-based lubricant dispersed in water or an aqueous solution into a heated molding die.
When the higher fatty acid-based lubricant is dispersed in water or the like, it becomes easy to uniformly spray the higher fatty acid-based lubricant on the inner surface of the molding die. Furthermore, when it is sprayed into the heated molding die, the water quickly evaporates, and the higher fatty acid-based lubricant can be uniformly attached to the inner surface of the molding die. The heating temperature of the molding die at that time needs to consider the temperature of the molding process described later, but it is sufficient to heat it to 100 ° C. or higher, for example. However, in order to form a uniform film of a higher fatty acid-based lubricant, it is preferable that the heating temperature be lower than the melting point of the higher fatty acid-based lubricant. For example, when lithium stearate is used as the higher fatty acid-based lubricant, the heating temperature is preferably less than 220 ° C.

なお、高級脂肪酸系潤滑剤を水等に分散させる際、その水溶液全体の質量を１００質量％としたときに、高級脂肪酸系潤滑剤が０．１〜５質量％、さらには、０．５〜２質量％の割合で含まれるようにすると、均一な潤滑膜が成形用金型の内面に形成されて好ましい。 When the higher fatty acid-based lubricant is dispersed in water or the like, when the total weight of the aqueous solution is 100% by mass, the higher fatty acid-based lubricant is 0.1 to 5% by mass, When included in a proportion of 2% by mass, a uniform lubricating film is preferably formed on the inner surface of the molding die.

また、高級脂肪酸系潤滑剤を水等へ分散させる際、界面活性剤をその水に添加しておくと、高級脂肪酸系潤滑剤の均一な分散が図れる。そのような界面活性剤として、例えば、アルキルフェノール系の界面活性剤、ポリオキシエチレンノニルフェニルエーテル（ＥＯ）６、ポリオキシエチレンノニルフェニルエーテル（ＥＯ）１０、アニオン性非イオン型界面活性剤、ホウ酸エステル系エマルボンＴ−８０等を用いることができる。これらを２種以上組合わせて使用しても良い。例えば、高級脂肪酸系潤滑剤としてステアリン酸リチウムを用いた場合、ポリオキシエチレンノニルフェニルエーテル（ＥＯ）６、ポリオキシエチレンノニルフェニルエーテル（ＥＯ）１０及びホウ酸エステルエマルボンＴ−８０の３種類の界面活性剤を同時に用いると好ましい。それらの１種のみを添加する場合に較べて複合添加した場合、ステアリン酸リチウムの水等への分散性が一層活性化されるからである。 Further, when the higher fatty acid-based lubricant is dispersed in water or the like, if the surfactant is added to the water, the higher fatty acid-based lubricant can be uniformly dispersed. Examples of such surfactants include alkylphenol surfactants, polyoxyethylene nonylphenyl ether (EO) 6, polyoxyethylene nonyl phenyl ether (EO) 10, anionic nonionic surfactants, and boric acid. Ester-based Emulbon T-80 or the like can be used. Two or more of these may be used in combination. For example, when lithium stearate is used as a higher fatty acid-based lubricant, three types of polyoxyethylene nonylphenyl ether (EO) 6, polyoxyethylene nonylphenyl ether (EO) 10 and borate ester Emulbon T-80 are available. It is preferable to use a surfactant at the same time. This is because the dispersibility of lithium stearate in water or the like is further activated when added in combination as compared with the case of adding only one of them.

また、噴霧に適した粘度の高級脂肪酸系潤滑剤の水溶液を得るために、その水溶液全体を１００体積％とした場合、界面活性剤の割合を１．５〜１５体積％とすると好ましい。
この他、少量の消泡剤（例えば、シリコン系の消泡剤等）を添加しても良い。水溶液の泡立ちが激しいと、それを噴霧したときに成形用金型の内面に均一な高級脂肪酸系潤滑剤の被膜が形成され難いからである。消泡剤の添加割合は、その水溶液の全体積を１００体積％としたときに、例えば０．１〜１体積％程度であればよい。 In order to obtain an aqueous solution of a higher fatty acid-based lubricant having a viscosity suitable for spraying, when the total amount of the aqueous solution is 100% by volume, the ratio of the surfactant is preferably 1.5 to 15% by volume.
In addition, a small amount of an antifoaming agent (for example, a silicon-based antifoaming agent) may be added. This is because when the foaming of the aqueous solution is intense, it is difficult to form a uniform higher fatty acid lubricant film on the inner surface of the molding die when sprayed. The addition ratio of the antifoaming agent may be, for example, about 0.1 to 1% by volume when the total volume of the aqueous solution is 100% by volume.

水等に分散した高級脂肪酸系潤滑剤の粒子は、最大粒径が３０μｍ未満であると、好適である。
最大粒径が３０μｍ以上となると、高級脂肪酸系潤滑剤の粒子が水溶液中に沈殿し易く、成形用金型の内面に高級脂肪酸系潤滑剤を均一に塗布することが困難となるからである。
高級脂肪酸系潤滑剤の分散した水溶液の塗布には、例えば、塗装用のスプレーガンや静電ガン等を用いて行うことができる。
なお、本発明者が高級脂肪酸系潤滑剤の塗布量と粉末成形体の抜出圧力との関係を実験により調べた結果、膜厚が０．５〜１．５μｍ程度となるように高級脂肪酸系潤滑剤を成形用金型の内面に付着させると好ましいことが解った。 The higher fatty acid-based lubricant particles dispersed in water or the like preferably have a maximum particle size of less than 30 μm.
When the maximum particle size is 30 μm or more, the higher fatty acid-based lubricant particles are likely to be precipitated in the aqueous solution, and it becomes difficult to uniformly apply the higher fatty acid-based lubricant to the inner surface of the molding die.
Application of the aqueous solution in which the higher fatty acid-based lubricant is dispersed can be performed using, for example, a spray gun for painting, an electrostatic gun, or the like.
In addition, as a result of investigating the relationship between the coating amount of the higher fatty acid-based lubricant and the extraction pressure of the powder molded body, the present inventor has found that the higher fatty acid-based lubricant has a film thickness of about 0.5 to 1.5 μm. It has been found preferable to apply a lubricant to the inner surface of the molding die.

（ｂ）成形工程
詳細は明らかではないが、この工程で、前述の金属石鹸皮膜がメカノケミカル反応によって生成されると考えられる。
すなわち、その反応によって、磁心用粉末（特に、絶縁皮膜）と高級脂肪酸系潤滑剤とが化学的に結合し、金属石鹸の被膜（例えば、高級脂肪酸の鉄塩被膜）が磁心用粉末の成形体表面に形成される。この金属石鹸の被膜は、その粉末成形体の表面に強固に結合し、成形用金型の内表面に付着していた高級脂肪酸系潤滑剤よりも遙かに優れた潤滑性能を発揮する。その結果、成形用金型の内面と粉末成形体の外面との接触面間での摩擦力が著しく低減し、高圧成形が可能になったと考えられる。 (B) Molding process Although details are not clear, it is considered that the above-mentioned metal soap film is generated by a mechanochemical reaction in this process.
That is, by the reaction, the magnetic core powder (particularly, the insulating film) and the higher fatty acid-based lubricant are chemically bonded, and the metal soap film (for example, the higher fatty acid iron salt film) is formed into the magnetic core powder. Formed on the surface. This metal soap film is firmly bonded to the surface of the powder molded body and exhibits a lubricating performance far superior to the higher fatty acid-based lubricant adhered to the inner surface of the molding die. As a result, it is considered that the frictional force between the contact surfaces of the inner surface of the molding die and the outer surface of the powder molded body is remarkably reduced, and high-pressure molding is possible.

なお、磁心用粉末の各粒子は絶縁皮膜で被覆されているが、絶縁皮膜中に金属石鹸の被膜形成を促進する元素（例えば、磁性粉末の主成分であるＦｅや本発明でいう第２元素）を主成分として含有しているので、それらを基に高級脂肪酸の金属塩被膜（金属石鹸被膜）が形成されると考えられる。
成形工程における「温間」とは、各状況に応じた適切な加熱条件の下で成形工程を行うことを意味する。もっとも、磁心用粉末と高級脂肪酸系潤滑剤との反応を促進するために、概して成形温度を１００℃以上とすると好ましい。また、絶縁皮膜の破壊や高級脂肪酸系潤滑剤の変質を防止するために、概して成形温度を２００℃以下とすると好ましい。そして、成形温度を１２０〜１８０℃とするとより好適である。 Each particle of the magnetic core powder is coated with an insulating film, but an element that promotes the formation of a metal soap film in the insulating film (for example, Fe as the main component of the magnetic powder or the second element in the present invention). ) As a main component, it is considered that a metal salt film of higher fatty acid (metal soap film) is formed based on them.
“Warm” in the molding process means that the molding process is performed under an appropriate heating condition according to each situation. However, in order to promote the reaction between the magnetic core powder and the higher fatty acid-based lubricant, it is generally preferable that the molding temperature is 100 ° C. or higher. In order to prevent the breakdown of the insulating film and the alteration of the higher fatty acid-based lubricant, it is generally preferable that the molding temperature is 200 ° C. or lower. And it is more suitable when molding temperature shall be 120-180 degreeC.

成形工程における「加圧」の程度も、所望する圧粉磁心の特性、磁心用粉末、絶縁皮膜、高級脂肪酸系潤滑剤の種類、成形用金型の材質や内面性状等に応じて適宜決定されるものであるが、この製造方法を用いると、従来の成形圧力を超越した高圧力下で成形可能である。このため、例えば、成形圧力を７００ＭＰａ以上、７８５ＭＰａ以上、１０００ＭＰａ以上、さらには、２０００ＭＰａとすることもできる。成形圧力が高圧である程、高密度の圧粉磁心が得られる。もっとも、成形用金型の寿命や生産性を考慮して、その成形圧力を２０００ＭＰａ以下、より望ましくは１５００ＭＰａ以下とするのが良い。 The degree of “pressurization” in the molding process is also determined appropriately according to the desired properties of the powder magnetic core, the magnetic core powder, the insulating film, the type of higher fatty acid lubricant, the molding die material and the inner surface properties, etc. However, when this manufacturing method is used, molding can be performed under high pressure exceeding the conventional molding pressure. For this reason, for example, the molding pressure can be set to 700 MPa or more, 785 MPa or more, 1000 MPa or more, or 2000 MPa. The higher the molding pressure, the higher the density magnetic core. However, in consideration of the life and productivity of the molding die, the molding pressure is preferably 2000 MPa or less, more preferably 1500 MPa or less.

なお、本発明者は、この温間高圧成形法を用いた場合、成形圧力が約６００ＭＰａで抜出圧力が最大となり、それ以上ではむしろ抜出圧力が低下することを実験により確認している。そして、成形圧力を９００〜２０００ＭＰａの範囲で変化させたときでさえ、抜出圧力が５ＭＰａ程度と、非常に低い値を維持した。このことからも、本発明の製造方法の一つである温間高圧成形法によって形成される金属石鹸被膜が、如何に潤滑性に優れるかが解る。この温間高圧成形法は、高圧成形による高密度化が要求される圧粉磁心の製造方法として最適であることが解る。このような現象は、高級脂肪酸系潤滑剤として、ステアリン酸リチウムを用いた場合に限らず、ステアリン酸カルシウムやステアリン酸亜鉛を用いた場合でも同様に生じ得る。 In addition, when this inventor used this warm high-pressure shaping | molding method, it has confirmed by experiment that a shaping | molding pressure is about 600 Mpa, and the extraction pressure becomes the maximum, and if it exceeds it, it will rather fall. And even when the molding pressure was changed in the range of 900 to 2000 MPa, the extraction pressure was maintained at a very low value of about 5 MPa. This also shows how the metal soap film formed by the warm high pressure forming method, which is one of the production methods of the present invention, is excellent in lubricity. It can be seen that this warm high-pressure forming method is optimal as a method for manufacturing a dust core that requires high density by high-pressure forming. Such a phenomenon can occur not only when lithium stearate is used as the higher fatty acid-based lubricant but also when calcium stearate or zinc stearate is used.

（ｃ）焼鈍工程
焼鈍工程は、残留する応力や歪を除去するために行う。これにより、圧粉磁心の保磁力が低減され、ヒステリシス損失が低減されると共に交流磁界に対する追従性も良くなり、圧粉磁心の磁気的特性が向上する。
このときの加熱温度は、磁性粉末の材質にも依るが、Ｆｅを主成分とする場合、３００〜６００℃、好ましくは、３５０〜５００℃である。また、加熱時間は、１〜３００分、好ましくは、５〜６０分である。
加熱時間が３００℃未満では残留応力や歪みの除去効果が乏しく、６００℃を越えると絶縁皮膜の破壊が進行し易くなる。また、加熱時間が１分未満では残留応力や歪みの除去効果が乏しく、３００分を越えて加熱してもそれ以上効果が向上しないからである。 (C) Annealing process An annealing process is performed in order to remove the residual stress and distortion. As a result, the coercive force of the dust core is reduced, the hysteresis loss is reduced, the followability to the AC magnetic field is improved, and the magnetic properties of the dust core are improved.
The heating temperature at this time depends on the material of the magnetic powder, but when Fe is the main component, it is 300 to 600 ° C, preferably 350 to 500 ° C. The heating time is 1 to 300 minutes, preferably 5 to 60 minutes.
When the heating time is less than 300 ° C., the effect of removing residual stress and strain is poor, and when the heating time exceeds 600 ° C., the breakdown of the insulating film easily proceeds. In addition, if the heating time is less than 1 minute, the effect of removing residual stress and strain is poor, and even if the heating exceeds 300 minutes, the effect is not improved any further.

本発明の圧粉磁心は、その構成粒子が耐熱性に優れた絶縁皮膜で被覆されているため、従来よりも焼鈍温度を高くしても（例えば、４００〜５００℃）、より確実に残留歪の除去を行うことができる。例えば、磁心用粉末の粉末成形体がＦｅを主成分とする場合なら、その成形体を４００℃以上に加熱した後に徐冷する焼鈍工程を行えば良い。
勿論、従来レベルの焼鈍温度（例えば、３００〜４００℃）で焼鈍工程を行う場合なら、本発明の絶縁皮膜は耐熱余裕が大きいため、焼鈍後における圧粉磁心の比抵抗の低下割合も少なくてすむ。 In the dust core of the present invention, the constituent particles are coated with an insulating film having excellent heat resistance. Therefore, even if the annealing temperature is higher than conventional (eg, 400 to 500 ° C.), the residual strain is more reliably obtained. Can be removed. For example, if the powder compact of the magnetic core powder contains Fe as a main component, an annealing process may be performed in which the compact is gradually cooled after being heated to 400 ° C. or higher.
Of course, if the annealing process is performed at a conventional level of annealing temperature (for example, 300 to 400 ° C.), the insulation film of the present invention has a large heat-resistance margin, and therefore the rate of decrease in the specific resistance of the dust core after annealing is small. I'm sorry.

（圧粉磁心の用途）
本発明の圧粉磁心は、各種の電磁機器、例えば、モータ、アクチュエータ、トランス、誘導加熱器（ＩＨ）、スピーカ等に利用できる。そして、本発明の圧粉磁心は、比抵抗と透磁率とを大きくすることができるから、エネルギー損失を抑制しつつ、各種機器の高性能化、小型化、省エネルギー化等を図ることが可能となる。例えば、自動車エンジン等の燃料噴射弁にこの圧粉磁心を内蔵すると、その圧粉磁心が磁気的特性に優れるのみならず高周波損失も小さいため、小型、高出力と共に高応答性をも実現できる。 (Use of dust core)
The dust core of the present invention can be used for various electromagnetic devices such as motors, actuators, transformers, induction heaters (IH), speakers, and the like. And since the dust core of the present invention can increase the specific resistance and permeability, it is possible to achieve high performance, downsizing, energy saving, etc. of various devices while suppressing energy loss. Become. For example, when this dust core is built in a fuel injection valve of an automobile engine or the like, the dust core not only has excellent magnetic characteristics, but also has low high-frequency loss, so that it is possible to realize small size, high output and high responsiveness.

さらに、本発明の圧粉磁心は、磁気的特性のみらず、耐熱性にも優れるため、高温環境下で使用される製品に使用すると、一層好ましい。その一例として、特開２００１−１１８７２５号公報等に記載されているエンジンバルブ駆動に用いられる電磁アクチュエータを挙げることができる。
その他、直流機、誘導機、同期機等のモータに本発明の圧粉磁心を用いると、モータの小型化と高出力化との両立を図れて好適である。 Furthermore, since the dust core of the present invention is excellent not only in magnetic properties but also in heat resistance, it is more preferable to use it in products used in a high temperature environment. As an example thereof, an electromagnetic actuator used for driving an engine valve described in JP-A-2001-118725 can be cited.
In addition, when the dust core of the present invention is used for a motor such as a DC machine, an induction machine, or a synchronous machine, it is preferable to achieve both reduction in size and increase in output of the motor.

次に、実施例を挙げて、本発明をより具体的に説明する。
（実施例）
（１）絶縁皮膜および磁心用粉末の製造
原料粉末として、市販のＦｅ粉末（ヘガネス社製ＡＢＣ１００．３０：純度９９．８％Ｆｅ、単位：質量％）を用意した。ここでは、原料粉末の分級等を特に行わず、入手した状態のままで使用したので、その粒径は約２０〜１８０μｍであった。 Next, an Example is given and this invention is demonstrated more concretely.
(Example)
(1) Production of Insulating Film and Magnetic Core Powder A commercially available Fe powder (ABC100.30: purity 99.8% Fe, unit: mass%) manufactured by Höganäs was prepared as a raw material powder. Here, since the raw material powder was not classified and used as it was, the particle size was about 20 to 180 μm.

この粉末への絶縁皮膜のコーティング処理を次の方法で行なった。
先ず、市販されている試薬であるＳｒＯまたはＭｇＯ（アルカリ土類金属元素の酸化物）と、リン酸（Ｈ₃ＰＯ₄）とをイオン交換水に投入し撹拌溶解した。このときの混合割合と、ＳｒＯまたはＭｇＯとＨ₃ＰＯ₄とのモル比を表２に示す。なお、ＳｒＯを用いたコーティング液は本実施例で使用し、ＭｇＯを用いたコーティング液およびリン酸のみのコーティング液は後述の比較例で使用した。 This powder was coated with an insulating film by the following method.
First, commercially available reagents SrO or MgO (an alkaline earth metal oxide) and phosphoric acid (H ₃ PO ₄ ) were added to ion-exchanged water and dissolved by stirring. Table 2 shows the mixing ratio and the molar ratio of SrO or MgO to H ₃ PO ₄ . A coating solution using SrO was used in this example, and a coating solution using MgO and a coating solution containing only phosphoric acid were used in comparative examples described later.

次に、１００ｍｌのビーカに入れた磁性粉末１００ｇの上から、上記の各種コーティング液を２０ｍｌ滴下した（接触工程）。それを電気炉に入れて、２００℃、３０ｍｉｎ間、大気中で加熱乾燥した（乾燥工程）。こうして、磁性粉末であるＦｅ粉末の表面に絶縁皮膜を定着させて、圧粉磁心の原料粉末となる磁心用粉末を製造した。 Next, 20 ml of the above various coating liquids were dropped from 100 g of magnetic powder placed in a 100 ml beaker (contact process). It was put in an electric furnace and dried by heating in the atmosphere at 200 ° C. for 30 minutes (drying process). In this way, the insulating film was fixed on the surface of the Fe powder, which was a magnetic powder, to produce a magnetic core powder as a raw material powder for a dust core.

（２）圧粉磁心の製造
得られた各種の磁心用粉末に対して、金型潤滑温間高圧成形法を行うことにより、リング状（外径：φ３９ｍｍ×内径φ３０ｍｍ×厚さ５ｍｍ）と板状（５ｍｍ×１０ｍｍ×５５ｍｍ）との２種の試験片をそれぞれの試料ごとに製作した。このリング状試験片は磁気特性評価用であり、板状試験片は電気抵抗評価用である。なお、この圧粉磁心の成形に際して、内部潤滑剤や樹脂バインダー等は、一切、磁心用粉末に混在させなかった。 (2) Manufacture of powder magnetic cores A ring-like shape (outer diameter: φ39 mm × inner diameter φ30 mm × thickness 5 mm) and a plate are obtained by performing mold-lubricating warm high-pressure molding on the obtained various magnetic core powders. Two types of test pieces having a shape (5 mm × 10 mm × 55 mm) were produced for each sample. This ring-shaped test piece is for evaluating magnetic properties, and the plate-shaped test piece is for evaluating electric resistance. In molding the dust core, no internal lubricant, resin binder, or the like was mixed in the core powder.

この温間高圧成形は、具体的には次のようにして行った。
（ａ）上記の各試験片形状に応じたキャビティを有する超硬製の成形用金型を用意した。この成形用金型をバンドヒータで予め１５０℃に加熱しておいた。また、この成形用金型の内周面には、予めＴｉＮコート処理を施し、その表面粗さを０．４Ｚとしておいた。 Specifically, this warm high pressure molding was performed as follows.
(A) A cemented carbide molding die having a cavity corresponding to each test piece shape described above was prepared. This molding die was preheated to 150 ° C. with a band heater. Further, the inner peripheral surface of this molding die was previously subjected to TiN coating treatment, and the surface roughness was set to 0.4Z.

そして、加熱した成形用金型の内周面に、水溶液に分散させたステアリン酸リチウムをスプレーガンにて、１ｃｍ³／秒程度の割合で均一に塗布した（塗布工程）。ここで用いた水溶液は、水に界面活性剤と消泡剤とを添加したものである。界面活性剤には、ポリオキシエチレンノニルフェニルエーテル（ＥＯ）６、（ＥＯ）１０及びホウ酸エステルエマルボンＴ−８０を用い、それぞれを水溶液全体（１００体積％）に対して１体積％づつ添加した。また、消泡剤には、ＦＳアンチフォーム８０を用い、水溶液全体（１００体積％）に対して０．２体積％添加した。 Then, lithium stearate dispersed in an aqueous solution was uniformly applied to the inner peripheral surface of the heated molding die with a spray gun at a rate of about 1 cm ³ / second (application step). The aqueous solution used here is obtained by adding a surfactant and an antifoaming agent to water. As the surfactant, polyoxyethylene nonylphenyl ether (EO) 6, (EO) 10 and boric acid ester Emulbon T-80 were used, and each was added by 1% by volume with respect to the entire aqueous solution (100% by volume). did. As the antifoaming agent, FS Antifoam 80 was used and 0.2% by volume was added to the entire aqueous solution (100% by volume).

また、ステアリン酸リチウムには、融点が約２２５℃で、平均粒径が２０μｍのものを用いた。その分散量は、上記水溶液１００ｃｍ³に対して２５ｇとした。そして、これをさらにボールミル式粉砕装置で微細化処理（テフロンコート鋼球：１００時間）し、得られた原液を２０倍に希釈して最終濃度１％の水溶液として、上記塗布工程に供した。 Further, lithium stearate having a melting point of about 225 ° C. and an average particle size of 20 μm was used. The dispersion amount was 25 g with respect to 100 cm ^{3 of the} aqueous solution. Then, this was further refined with a ball mill type pulverizer (Teflon-coated steel balls: 100 hours), and the obtained stock solution was diluted 20 times to give an aqueous solution having a final concentration of 1%, which was used in the coating step.

（ｂ）ステアリン酸リチウムが内面に塗布されたその成形用金型へ、それと同温の１５０℃に加熱しておいた上記の各種磁心用粉末を充填した（充填工程）。 (B) The above-mentioned various magnetic core powders that had been heated to 150 ° C., the same temperature as that, were filled into the molding die coated with lithium stearate (filling step).

（ｃ）成形用金型を１５０℃に保持したまま、１１７６ＭＰａの成形圧力で、充填された各種磁心用粉末を温間加圧成形した（成形工程）。
なお、この温間高圧成形に際して、いずれの磁心用粉末も成形用金型とかじり等を生じることがなく、５ＭＰａ程度の低い抜圧で粉末成形体をその金型から取出すことができた。 (C) While filling the mold for molding at 150 ° C., the filled various magnetic core powders were warm-press molded at a molding pressure of 1176 MPa (molding process).
In this warm high-pressure molding, none of the magnetic core powder was galling with the molding die, and the powder compact could be removed from the die with a low depressurization pressure of about 5 MPa.

（ｄ）得られた粉末成形体に、大気中で、焼鈍温度：４００℃または５００℃、焼鈍時間：３０分の焼鈍を適宜施した。 (D) The obtained powder compact was appropriately subjected to annealing in the air at an annealing temperature of 400 ° C. or 500 ° C. and an annealing time of 30 minutes.

（比較例）
比較例も、実施例と同様に、先ず、磁性粉末に絶縁皮膜を被覆して磁心用粉末を製造し、その磁心用粉末を用いて圧粉磁心を製造した。実施例と異なるところは、磁性粉末の表面被覆に使用したコーティング液の組成である。この組成は表２に併せて示してある。 (Comparative example)
In the comparative example, similarly to the example, first, a magnetic core powder was manufactured by coating an insulating film on the magnetic powder, and a dust core was manufactured using the magnetic core powder. The difference from the examples is the composition of the coating solution used for the surface coating of the magnetic powder. This composition is also shown in Table 2.

（絶縁皮膜の評価）
先ず、上記の板状試験片を用いて、それらの絶縁皮膜の耐熱性を評価した。評価方法としては、成形後のままの試験片（焼鈍前の試験片）と、４００℃で焼鈍した試験片と、５００℃で焼鈍した試験片との３種をそれぞれ用意して、各々について、（体積）比抵抗を適宜測定した。なお、比抵抗の測定は、マイクロオームメータ（メーカ：ヒューレットパカード（ＨＰ）社、型番：３４４２０Ａ）を用いて４端子法により測定した（以下、同様）。その測定結果を表３に示す。 (Evaluation of insulation film)
First, the heat resistance of those insulating coatings was evaluated using the above plate-shaped test pieces. As an evaluation method, three types of a test piece as it is after molding (a test piece before annealing), a test piece annealed at 400 ° C., and a test piece annealed at 500 ° C. are prepared, respectively. The (volume) specific resistance was appropriately measured. The specific resistance was measured by a four-terminal method using a micro-ohm meter (manufacturer: Hewlett-Packard (HP), model number: 34420A) (hereinafter the same). The measurement results are shown in Table 3.

いずれの試験片も、焼鈍前後で比抵抗が低下している。しかし、実施例の場合、４００℃の焼鈍および５００℃の焼鈍のいずれの場合においても、比較例よりも大きな比抵抗が維持されている。特に実施例の場合では、４００℃の焼鈍のみらず、５００℃の焼鈍を施した場合でも、十分に高い比抵抗が維持されていた。こうして、本発明に係る絶縁皮膜の優れた耐熱性が確認された。 In any specimen, the specific resistance decreases before and after annealing. However, in the case of an Example, the specific resistance larger than a comparative example is maintained also in any case of 400 degreeC annealing and 500 degreeC annealing. In particular, in the case of the example, a sufficiently high specific resistance was maintained not only when annealing at 400 ° C. but also when annealing at 500 ° C. was performed. Thus, the excellent heat resistance of the insulating film according to the present invention was confirmed.

（圧粉磁心の評価）
次に、前述したリング状試験片と板状試験片とを各種用意して、それらの磁気的特性と電気的特性とを評価した。この場合も、焼鈍の有無、焼鈍温度を変更して、種々の測定を行った。ここでは、前述の比抵抗の他、各種磁気特性、密度についても測定した。この測定結果を表４に示す。 (Evaluation of dust core)
Next, various ring-shaped test pieces and plate-shaped test pieces were prepared, and their magnetic characteristics and electrical characteristics were evaluated. Also in this case, various measurements were performed by changing the presence / absence of annealing and the annealing temperature. Here, in addition to the specific resistance described above, various magnetic properties and densities were also measured. The measurement results are shown in Table 4.

なお、磁気的特性の内、静磁場特性は直流自記磁束計（メーカ：東英工業、型番：ＭＯＤＥＬ−ＴＲＦ）により測定した。交流磁場特性は交流Ｂ−Ｈカーブトレーサ（メーカ：岩崎通信機（株）、型番：ＳＹ−８２３２）により測定した。表中の交流磁場特性は、圧粉磁心を８００Ｈｚ、１．０Ｔの磁場中に置いたときの高周波損失を測定したものである。また、静磁場中の磁束密度は、その磁界の強さを順次１、２、５、８、１０ｋＡ／ｍと順次変更したときにできる磁束密度を示したものであり、各表中にそれぞれＢ_1k、Ｂ_2k、Ｂ_5k、Ｂ_8k、Ｂ_10kとして示した。なお、本明細書中で、保磁力ｂＨｃは最大磁場２ｋＡ／ｍでの磁化曲線から測定した値とする。密度は、アルキメデス法により測定した。 Of the magnetic characteristics, the static magnetic field characteristics were measured by a direct current magnetic flux meter (manufacturer: Toei Kogyo, model number: MODEL-TRF). The AC magnetic field characteristics were measured with an AC BH curve tracer (manufacturer: Iwasaki Tsushinki Co., Ltd., model number: SY-8232). The AC magnetic field characteristics in the table are obtained by measuring high-frequency loss when the dust core is placed in a magnetic field of 800 Hz and 1.0 T. The magnetic flux density in the static magnetic field indicates the magnetic flux density that can be obtained when the strength of the magnetic field is sequentially changed to 1, 2, 5, 8, 10 kA / m. _It was shown as _1k , _B2k , _B5k , _B8k , _B10k . In this specification, the coercive force bHc is a value measured from a magnetization curve with a maximum magnetic field of 2 kA / m. The density was measured by the Archimedes method.

なお、現状では、コーティング液の濃度と絶縁皮膜の膜厚等との定量的関係は明確ではないが、コーティング液の濃度が濃い程、絶縁皮膜の膜厚が厚くなり、比抵抗が大きくなり、高周波損失が低減されていると考えられる。従って、コーティング液の濃度次第で高周波損失をさらに低減できると考えられる。ちなみに、実施例についてＴＥＭ（透過型電子顕微鏡）を用いて膜厚を測定したところ、２０〜３０ｎｍであった。 In addition, at present, the quantitative relationship between the concentration of the coating liquid and the film thickness of the insulating film is not clear, but the higher the concentration of the coating liquid, the thicker the film of the insulating film and the higher the specific resistance. It is considered that high-frequency loss is reduced. Therefore, it is considered that the high frequency loss can be further reduced depending on the concentration of the coating liquid. Incidentally, when the film thickness was measured using TEM (Transmission Electron Microscope) for the examples, it was 20 to 30 nm.

次に、実施例と比較例との磁気測定の結果を対比すると、実施例のものは比較例のものよりも静磁場特性および交流磁場特性の両方で優れている。すなわち、各周波数域で高い磁束密度が得られ、高周波損失（特に、渦電流損失）も少なくなっている。
以上のように、本発明によれば、耐熱性に優れる絶縁皮膜が得られる。また、その絶縁皮膜を磁性粉末に被覆してなる磁心用粉末、および、その磁心用粉末を加圧成形してなる圧粉磁心は、高温域まで大きな比抵抗を示す。 Next, when comparing the magnetic measurement results of the example and the comparative example, the example is superior in both the static magnetic field characteristic and the alternating magnetic field characteristic to the comparative example. That is, high magnetic flux density is obtained in each frequency range, and high-frequency loss (especially eddy current loss) is also reduced.
As described above, according to the present invention, an insulating film having excellent heat resistance can be obtained. Further, a magnetic core powder obtained by coating the insulating film with a magnetic powder, and a powder magnetic core formed by pressure-molding the magnetic core powder exhibit a large specific resistance up to a high temperature range.

特に、その圧粉磁心を焼鈍した場合、絶縁皮膜が優れた耐熱性を有するために、その比抵抗が急減せず、さらには、残留歪が除去されてヒステリシス損失が低減される。 In particular, when the powder magnetic core is annealed, since the insulating film has excellent heat resistance, its specific resistance does not decrease rapidly, and further, residual strain is removed and hysteresis loss is reduced.

Claims

A first element group consisting of phosphorus (P), oxygen (O), and iron (Fe);
An essential constituent element is a second element capable of producing a divalent or higher cation having a hexacoordinate ion radius defined by Shannon (R, D) of 0.073 nm or more,
An insulating film characterized by substantially not containing boron (B).

The insulating film according to claim 1, wherein the second element is at least one of an alkaline earth metal element and / or a rare earth element (RE).

The alkaline earth metal element is either calcium (Ca) or strontium (Sr),
The insulating film according to claim 2, wherein the rare earth element is yttrium (Y).

The first element group is an element constituting a network former,
The second element is an element constituting a network modifier,
The insulating film according to claim 1, wherein the insulating film is a glassy insulating film formed by the network former and the network modifier.

The insulating film according to claim 1, wherein the surface of the magnetic material is coated.

The insulating film according to claim 5, wherein the magnetic material is a magnetic powder containing iron (Fe) as a main component.

The insulating film according to claim 5 or 6, wherein the film thickness is 10 to 100 nm.

The insulating film according to any one of claims 1 to 7, wherein the heat-resistant temperature is 400 ° C or higher.

To a coating treatment liquid prepared by mixing a compound and / or salt of an element capable of generating a divalent or higher cation having a 6-coordinate ion radius defined by Shannon of 0.073 nm or more and phosphoric acid, A contact process for contacting a material to be coated;
A drying step of drying the mating material after the contact step,
An insulating film manufacturing method comprising forming an insulating film on the surface of the counterpart material.

The method for producing an insulating film according to claim 9, wherein the compound and / or salt includes an alkaline earth metal element and / or a rare earth element.

The method of manufacturing an insulating film according to claim 9, wherein the counterpart material is a magnetic material.

Magnetic powder,
A bivalent or higher cation having a 6-coordinate ionic radius defined by Shannon and a first element group consisting of P, O and Fe coated on the surface of the magnetic powder and having a radius of 0.073 nm or more can be generated. An insulating film containing the second element as an essential constituent element and substantially free of B;
A magnetic core powder characterized by comprising:

To a coating treatment liquid prepared by mixing a compound and / or salt of an element capable of generating a divalent or higher cation having a 6-coordinate ion radius defined by Shannon of 0.073 nm or more and phosphoric acid, A contact step of contacting magnetic powder;
A drying step of drying the magnetic powder after the contact step,
An insulating film is formed on the surface of the magnetic powder. A method for producing a magnetic core powder.

B is substantially composed of a first element group consisting of P and O and a second element capable of producing a bivalent or higher cation having a six-coordinate ion radius defined by Shannon of 0.073 nm or more, which is capable of producing a divalent or higher cation. A powder magnetic core obtained by pressure-molding a magnetic core powder in which an insulating film not included is coated on the surface of the magnetic powder.

The specific resistance ρ is 5 μΩm or more,
The dust core according to claim 14, wherein the coercive force bHc is 350 A / m or less.

A first element group consisting of P, O, and Fe and a second element capable of generating a divalent or higher cation having a hexacoordinate ion radius defined by Shannon of 0.073 nm or more as an essential constituent element are B A filling step of filling a molding die with magnetic core powder formed by coating the surface of the magnetic powder with an insulating film substantially free of
A molding step of pressure-molding the magnetic core powder in the molding die;
A method for producing a powder magnetic core comprising:

The filling step is a step of filling the magnetic core powder into the molding die coated with a higher fatty acid-based lubricant on the inner surface,
The method of manufacturing a dust core according to claim 16, wherein the molding step is a warm high-pressure molding step in which a metal soap film is formed between the magnetic core powder and the inner surface of the molding die.

The magnetic powder is a powder mainly composed of Fe,
The higher fatty acid-based lubricant is at least one of lithium stearate (StLi), calcium stearate (Ca) and zinc stearate (StZn),
The method of manufacturing a dust core according to claim 17, wherein the metal soap film is made of iron stearate.

Furthermore, the manufacturing method of the powder magnetic core of Claim 16 which performs the annealing process which anneals the powder compact obtained after the said shaping | molding process.

The powder compact is made of a powder mainly composed of Fe,
The method for manufacturing a dust core according to claim 19, wherein the annealing step is a step of gradually cooling after heating to 300 ° C or higher.