JP4761836B2 - Mg-containing iron oxide coated iron powder - Google Patents
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この発明は、少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜が鉄粉末の表面に形成されたＭｇ含有酸化膜被覆鉄粉末に関するものであり、このＭｇ含有酸化膜被覆鉄粉末で作製した複合軟磁性材は低鉄損を必要とする各種電磁気回路部品、例えば、モータ、アクチュエータ、ヨーク、コア、リアクトルなどの各種電磁気部品の素材として使用される。 The present invention relates to an Mg-containing oxide film-coated iron powder in which an Mg—Fe—O ternary oxide deposition film containing at least (Mg, Fe) O is formed on the surface of the iron powder. The composite soft magnetic material made of film-coated iron powder is used as a material for various electromagnetic circuit components that require low iron loss, for example, various electromagnetic components such as motors, actuators, yokes, cores, and reactors.
一般に、各種電磁気回路部品に使用される軟磁性材は、鉄損が小さいことが要求されるため、電気抵抗を高くして渦電流損を低減させ、保磁力を小さくしてヒステリシス損を低減させることは一般に知られていることである。さらに、近年、電磁気回路の小型化、高応答化が求められているところから、磁束密度がより高いことも重要視されている。 In general, soft magnetic materials used in various electromagnetic circuit components are required to have low iron loss. Therefore, electrical resistance is increased to reduce eddy current loss, and coercive force is reduced to reduce hysteresis loss. That is generally known. Furthermore, in recent years, since the miniaturization and high response of the electromagnetic circuit have been demanded, higher magnetic flux density is also regarded as important.
かかる高比抵抗を有する軟磁性材料を製造するための原料粉末の一例として鉄粉末の表面にＭｇ含有フェライト（（ＭｇＦｅ）３Ｏ４）として知られており、スピネル型結晶構造を有する）膜を被覆したＭｇ含有酸化膜被覆鉄粉末が知られている（特許文献１参照）。
しかし、従来のＭｇ含有フェライト膜を被覆したＭｇ含有酸化膜被覆鉄粉末は、鉄粉末の表面にＭｇ含有フェライト膜を化学的方法により被覆するために、プレス成形した圧粉体に高温歪取り焼成を行って得られた複合軟磁性材は，フェライト膜が不安定となり変化して絶縁性が低下すると共に、鉄粉末の表面に対するＭｇ含有フェライト膜の密着性が十分でなく、従来のＭｇ含有フェライト膜を被覆したＭｇ含有酸化膜被覆鉄粉末をプレス成形し焼成することにより作製した複合軟磁性材はプレス成形中にＭｇ含有フェライト膜が剥離したり破れるなどして十分な絶縁効果が発揮できず、したがって、十分な高比抵抗が得られないという欠点があった。 However, conventional iron powder coated with Mg-containing oxide film coated with Mg-containing ferrite film is high-temperature strain-removed and fired on pressed green compact to coat Mg-containing ferrite film on the surface of iron powder by chemical method. In the composite soft magnetic material obtained by performing the above, the ferrite film becomes unstable and changes to lower the insulation, and the adhesion of the Mg-containing ferrite film to the surface of the iron powder is not sufficient. The composite soft magnetic material produced by press-molding and firing Mg-containing oxide film-coated iron powder coated with a film cannot exhibit sufficient insulation effect due to peeling or tearing of the Mg-containing ferrite film during press molding Therefore, there is a drawback that a sufficiently high specific resistance cannot be obtained.
そこで、本発明者らは、プレス成形しても、プレス成形時に鉄粉末表面の高抵抗酸化膜が破れることが無く表面に酸化膜が強固に密着した鉄粉末であり、プレス成形後に高温歪取り焼成を行っても表面の絶縁性が低下することなく高抵抗で渦電流損失が低くなり、また歪取り焼鈍の焼成を行った場合により保磁力が低減できてヒステリシス損失が低くなるＭｇ含有酸化膜被覆鉄粉末を作製すべく研究を行った。その結果、鉄粉末を予め酸化雰囲気中で加熱することにより鉄粉末の表面に酸化鉄膜を形成した鉄粉末（以下、酸化処理鉄粉末という）を作製し、この酸化処理鉄粉末にＭｇ粉末を添加し混合して得られた混合粉末を不活性ガス雰囲気または真空雰囲気中で加熱するなどしたのち、さらに酸化性雰囲気中で加熱する後酸化処理を施すと、
（イ）一般に知られているＭｇＯ−ＦｅＯ−Ｆｅ２Ｏ３系の中でで代表される（Ｍｇ，Ｆｅ）Ｏ、（Ｍｇ，Ｆｅ）３Ｏ４などのＭｇ−Ｆｅ−Ｏ三元系各種酸化物のうちで、少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜が鉄粉末の表面に形成され、この少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜が鉄粉末の表面に被覆されたＭｇ含有酸化膜被覆鉄粉末は、従来の鉄粉末の表面にＭｇ含有フェライト膜を形成したＭｇ含有酸化膜被覆鉄粉末に比べて酸化膜の鉄粉末に対する密着性が格段に優れることから、プレス成形中に絶縁皮膜である酸化膜が破壊されて鉄粉末同士が接触することが少なく、プレス成形後に高温歪取り焼成を行っても酸化膜の絶縁性が低下することなく高抵抗を維持することができるので渦電流損失が低くなり、さらに歪取り焼成を行った場合に、より保磁力が低減できることからヒステリシス損失を低く抑えることができ、したがって、低鉄損を有する複合軟磁性材料が得られること、
（ロ）前記Ｍｇ含有酸化膜被覆鉄粉末のＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜に含まれる（Ｍｇ，Ｆｅ）Ｏは、結晶質のＭｇＯ固溶ウスタイト（ＭｇＯがウスタイト（ＦｅＯ）に固溶している物質）であることが一層好ましいこと、
（ハ）前記鉄粉末と少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜との界面領域には、鉄粉末の中心部に不可避不純物として含まれている硫黄よりも高濃度の硫黄を含む硫黄濃化層が形成されること、
（ニ）前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は結晶粒径：２００ｎｍ以下の微細結晶組織を有すること、
（ホ）前記鉄粉末の表面に形成されている少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、その最表面に含まれるＭｇＯの量が多いほど好ましく、その最表面は実質的にＭｇＯで構成されていることが最も好ましいこと、などの知見が得られたのである。
Therefore, the present inventors are an iron powder in which the high resistance oxide film on the surface of the iron powder is not broken during the press molding, and the oxide film is firmly adhered to the surface during the press molding. Mg-containing oxide film with low resistance and low eddy current loss without reducing surface insulation even when baked, and reduced coercive force and reduced hysteresis loss when baked with strain relief annealing Research was carried out to produce coated iron powder. As a result, the iron powder was heated in an oxidizing atmosphere in advance to produce an iron powder in which an iron oxide film was formed on the surface of the iron powder (hereinafter referred to as oxidized iron powder), and Mg powder was added to the oxidized iron powder. After heating the mixed powder obtained by adding and mixing in an inert gas atmosphere or a vacuum atmosphere, and further performing an oxidation treatment after heating in an oxidizing atmosphere,
(B) Various Mg-Fe-O ternary systems such as (Mg, Fe) O, (Mg, Fe) 3 O 4 and the like represented by the generally known MgO-FeO-Fe 2 O 3 systems Among the oxides, an Mg—Fe—O ternary oxide deposition film containing at least (Mg, Fe) O is formed on the surface of the iron powder, and this Mg—Fe— containing at least (Mg, Fe) O is formed. The Mg-containing oxide film-coated iron powder in which the O ternary oxide deposited film is coated on the surface of the iron powder is compared with the Mg-containing oxide film-coated iron powder in which the Mg-containing ferrite film is formed on the surface of the conventional iron powder. Since the adhesion of the oxide film to the iron powder is remarkably excellent, the oxide film, which is an insulating film, is hardly broken during press molding, and the iron powder is less likely to come into contact with each other. Maintains high resistance without degrading oxide insulation Therefore, the eddy current loss is reduced, and when the strain relief firing is performed, the coercive force can be further reduced, so that the hysteresis loss can be suppressed low. Therefore, a composite soft magnetic material having a low iron loss can be obtained. To obtain,
(B) (Mg, Fe) O contained in the Mg—Fe—O ternary oxide deposited film of the Mg-containing oxide film-coated iron powder is crystalline MgO solid solution wustite (MgO becomes wustite (FeO)). It is more preferable that the substance is a solid solution)
(C) In the interface region between the iron powder and the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O, sulfur contained as an inevitable impurity in the center of the iron powder A sulfur-enriched layer containing a high concentration of sulfur is formed,
(D) the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has a fine crystal structure with a crystal grain size of 200 nm or less;
(E) The Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the iron powder is preferably as the amount of MgO contained in the outermost surface is larger, It has been found that it is most preferable that the outermost surface is substantially composed of MgO.
この発明は、かかる知見に基づいて成されたものであって、
（１）少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜が鉄粉末の表面に被覆されており、該（Ｍｇ，Ｆｅ）Ｏは、結晶質のＭｇＯ固溶ウスタイト相であるＭｇ含有酸化膜被覆鉄粉末、
（２）前記Ｍｇ含有酸化膜被覆鉄粉末は、鉄粉末と前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜との界面領域に、鉄粉末の中心部に含まれる硫黄よりも高濃度の硫黄を含む硫黄濃化層を有する前記（１）記載のＭｇ含有酸化膜被覆鉄粉末、
（３）前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、結晶粒径：２００ｎｍ以下の微細結晶組織を有する前記（１）または（２）記載のＭｇ含有酸化膜被覆鉄粉末、
（４）前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、その最表面が実質的にＭｇＯで構成されている前記（１）、（２）または（３）記載のＭｇ含有酸化膜被覆鉄粉末、に特徴を有するものである。
This invention is made based on such knowledge,
(1) An Mg-Fe-O ternary oxide deposition film containing at least (Mg, Fe) O is coated on the surface of the iron powder , and the (Mg, Fe) O is a crystalline MgO solid solution. Mg-containing oxide film-coated iron powder that is a wustite phase ,
(2) The Mg-containing oxide film-coated iron powder is formed in an interface region between the iron powder and the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O at the center of the iron powder. The Mg-containing oxide film-coated iron powder according to (1), which has a sulfur-concentrated layer containing a higher concentration of sulfur than the contained sulfur;
(3) The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has a fine crystal structure with a crystal grain size of 200 nm or less. The Mg according to (1) or (2) Containing oxide film coated iron powder,
(4) The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O has the outermost surface substantially composed of MgO (1), (2) or ( 3) The Mg-containing oxide film-coated iron powder described in 3) .
この発明の前記（１）〜（３）記載のＭｇ含有酸化膜被覆鉄粉末は、鉄粉末を予め酸化雰囲気中で加熱することにより鉄粉末の表面に酸化鉄膜を形成した酸化処理鉄粉末を作製し、この酸化処理鉄粉末にＭｇ粉末を添加し混合して得られた混合粉末を不活性ガス雰囲気または真空雰囲気中で加熱するなどしたのち、さらに酸化性雰囲気中で加熱する後酸化処理を施すことにより作製することができることは既に述べたが、一層具体的には、鉄粉末を予め酸化雰囲気中、温度：５０〜５００℃に加熱して酸化処理することにより鉄粉末の表面に酸化鉄膜を形成した酸化処理鉄粉末を作製し、この酸化処理鉄粉末にＭｇ粉末を添加し混合して得られた混合粉末を温度：１５０〜１１００℃、圧力：１×１０−１２〜１×１０−１ＭＰａの不活性ガス雰囲気または真空雰囲気中で加熱した後、さらに酸化性雰囲気中、温度：５０〜３５０℃で加熱する後酸化処理を施すことにより作製する。
The Mg-containing oxide film-coated iron powder according to (1) to (3) of the present invention is an oxidized iron powder in which an iron oxide film is formed on the surface of the iron powder by heating the iron powder in an oxidizing atmosphere in advance. The mixed powder obtained by adding and mixing Mg powder to this oxidized iron powder is heated in an inert gas atmosphere or vacuum atmosphere, and then heated in an oxidizing atmosphere, followed by oxidation treatment. Although it has already been described that it can be produced by application, more specifically, iron powder is heated on an oxidizing atmosphere in advance in an oxidizing atmosphere at a temperature of 50 to 500 ° C. to oxidize the iron powder on the surface of the iron powder. An oxidized iron powder having a film formed thereon was prepared, and mixed powder obtained by adding and mixing Mg powder to this oxidized iron powder was temperature: 150 to 1100 ° C., pressure: 1 × 10 −12 to 1 × 10. -1 MPa of inert After heating in a scan atmosphere or vacuum atmosphere, further oxidizing atmosphere, temperature: 50 to 350 produced by the oxidation process is subjected after heating at ° C..
この発明の前記（４）記載の最表面が実質的にＭｇＯで構成されているＭｇＯ固溶ウスタイト相を含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、鉄粉末を予め酸化雰囲気中、温度：５０〜５００℃に加熱して酸化処理することにより鉄粉末の表面に酸化鉄膜を形成した酸化処理鉄粉末を作製し、この酸化処理鉄粉末にＭｇ粉末を一層多く添加し混合して得られた混合粉末を温度：１５０〜１１００℃、圧力：１×１０−１２〜１×１０−１ＭＰａの不活性ガス雰囲気または真空雰囲気中で加熱した後、さらに酸化性雰囲気中で一層長時間加熱する後酸化処理を施すことにより得られる。
The Mg—Fe—O ternary oxide deposited film containing the MgO solid solution wustite phase, the outermost surface of which is substantially composed of MgO, according to the present invention (4) , the iron powder in advance in an oxidizing atmosphere, Temperature: An oxidized iron powder having an iron oxide film formed on the surface of the iron powder is prepared by heating to 50 to 500 ° C., and adding more Mg powder to the oxidized iron powder and mixing. The obtained mixed powder was heated in an inert gas atmosphere or vacuum atmosphere at a temperature of 150 to 1100 ° C. and a pressure of 1 × 10 −12 to 1 × 10 −1 MPa, and then further in an oxidizing atmosphere for a longer time. It is obtained by subjecting it to an oxidation treatment after heating.
この発明の鉄粉末の表面に形成されているＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、少なくとも（Ｍｇ，Ｆｅ）Ｏを含む。このＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜に含まれる（Ｍｇ，Ｆｅ）Ｏは、結晶質のＭｇＯ固溶ウスタイト相であることが一層好ましい。この少なくとも（Ｍｇ，Ｆｅ）Ｏを含む堆積膜の最表面はＭｇＯで構成さていることが最も好ましい。（Ｍｇ，Ｆｅ）：Ｏ＝１：１のものだけではなくＯが固溶幅を有していても良い。
「堆積膜」という用語は、通常、真空蒸発やスパッタされた皮膜構成原子が例えば基板上に堆積した皮膜を示すが、この発明の鉄粉末の表面に形成されている少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、酸化処理鉄粉末表面の酸化鉄（Ｆｅ−O）とMｇが反応を伴って当該鉄粉末表面に堆積した皮膜を示す。そして、この鉄粉末の表面に形成されている少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜の膜厚は、圧粉成形した複合軟磁性材の高磁束密度と高比抵抗を得るために、５ｎｍ〜５００ｎｍの範囲内にあることが好ましい。膜厚が５ｎｍより薄いと圧粉成形した複合軟磁性材の比抵抗が充分でなく渦電流損が増加するので好ましくなく、一方、膜厚が５００ｎｍより厚いと圧粉成形した複合軟磁性材の磁束密度が低下して好ましくないからである。さらに好ましい膜厚は５ｎｍ〜２００ｎｍの範囲内である。
The Mg—Fe—O ternary oxide deposited film formed on the surface of the iron powder of the present invention contains at least (Mg, Fe) O. (Mg, Fe) O contained in the Mg—Fe—O ternary oxide deposited film is more preferably a crystalline MgO solid solution wustite phase. Most preferably, the outermost surface of the deposited film containing at least (Mg, Fe) O is made of MgO. In addition to (Mg, Fe): O = 1: 1, O may have a solid solution width.
The term “deposited film” usually indicates a film in which atoms constituting the film formed by vacuum evaporation or sputtering are deposited on, for example, a substrate, but at least (Mg, Fe) O formed on the surface of the iron powder of the present invention. The Mg—Fe—O ternary oxide deposited film containing iron is a film in which iron oxide (Fe—O) and Mg on the surface of oxidized iron powder are deposited on the iron powder surface with a reaction. The film thickness of the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the iron powder is equal to the high magnetic flux density of the compacted composite soft magnetic material. In order to obtain a high specific resistance, it is preferably in the range of 5 nm to 500 nm. If the film thickness is less than 5 nm, the specific resistance of the powder-molded composite soft magnetic material is not sufficient and the eddy current loss increases. On the other hand, if the film thickness is thicker than 500 nm, it is not preferable. This is because the magnetic flux density is lowered, which is not preferable. A more preferable film thickness is in the range of 5 nm to 200 nm.
この発明のＭｇ含有酸化膜被覆鉄粉末を構成する前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜と鉄粉末との界面領域に、鉄粉末の中心部に含まれる硫黄よりも高濃度の硫黄を含む硫黄濃化層を有する。この硫黄濃化層を有することはオージェ電子分光法により硫黄濃度を測定し、これをグラフに表すと、硫黄濃度ピークを示すことから確認することができる。界面領域にこの様な硫黄濃化層を有することにより少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜の鉄粉末表面に対する密着性がより一層優れるようになり、圧粉成形時の粉末の変形に堆積膜が追従して被覆の破れを防止することができ、焼成時にも鉄粉末同士の接触結合を防止することができて高抵抗を維持することができ、したがって渦電流損失が低くなる。硫黄濃化層の硫黄は、鉄粉末には不可避不純物として硫黄が含まれており、大部分はこの鉄粉末の表面部分に含まれる硫黄から供給されると考えられる。 The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O constituting the Mg-containing oxide film-coated iron powder of the present invention is composed of the Mg—Fe containing at least (Mg, Fe) O. In the interface region between the -O ternary oxide deposited film and the iron powder, a sulfur-enriched layer containing a higher concentration of sulfur than the sulfur contained in the central portion of the iron powder is provided. Having this sulfur-concentrated layer can be confirmed from the fact that the sulfur concentration is measured by Auger electron spectroscopy, and this is shown in a graph, showing a sulfur concentration peak. By having such a sulfur-concentrated layer in the interface region, the adhesion of the Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O to the iron powder surface becomes even better. The deposited film can follow the deformation of the powder at the time of compacting to prevent the coating from being torn, the contact bonding between the iron powders can be prevented even during firing, and high resistance can be maintained, Therefore, eddy current loss is reduced. The sulfur in the sulfur-concentrated layer is considered to be supplied from sulfur contained in the surface portion of the iron powder because the iron powder contains sulfur as an unavoidable impurity.
この発明の鉄粉末の表面に形成されている前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、その結晶粒が微細であるほど好ましく、結晶粒径が２００ｎｍ以下の微細結晶組織を有する事が好ましい。この様な微細結晶組織を有することにより、圧粉成形時の粉末の変形に微結晶Ｍｇ−Ｆｅ−Ｏ三元系酸化物堆積膜が追従して被覆の破れを防止することができ、焼成時にも鉄粉末同士の接触結合を防止することができ、また、高温歪取り焼成を行っても酸化物が安定で絶縁性低下が防止でき高抵抗で渦電流損失が低くなる。結晶粒径が２００ｎｍより大きいとＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜の膜厚が５００ｎｍよりも厚くなり圧粉成形した複合軟磁性材の磁束密度が低下するようになるので好ましくない。
また、この発明のＭｇ含有酸化膜被覆鉄粉末を構成する前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、その最表面におけるＭｇＯの含有量が多くなるほど好ましく、実質的にＭｇＯで構成されていることが最も好ましい。最表面が実質的にＭｇＯであると、プレス成形した圧粉体の焼成時にもＦｅの拡散が防止され鉄粉末同士の接触結合を防止することができ絶縁性低下が防止でき高抵抗で渦電流損失が低くなるからである。
この発明のＭｇ含有酸化膜被覆鉄粉末を構成する前記少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は、Ｍｇの一部をＭｇに対して１０％以下のＡｌ，Ｓｉ，Ｎｉ，Ｍｎ，Ｚｎ，Ｃｕ，Ｃｏのうち１種以上で置換した疑三元系酸化物堆積膜でも良い。
The Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O formed on the surface of the iron powder of the present invention is preferably as the crystal grains are finer, and the crystal grain size is It is preferable to have a fine crystal structure of 200 nm or less. By having such a fine crystal structure, the microcrystalline Mg—Fe—O ternary oxide deposited film can follow the deformation of the powder during compacting and prevent the coating from being broken. In addition, contact bonding between iron powders can be prevented, and even when high-temperature strain relief firing is performed, the oxide is stable and insulation deterioration can be prevented, and eddy current loss is reduced with high resistance. If the crystal grain size is larger than 200 nm, the Mg—Fe—O ternary oxide deposited film becomes thicker than 500 nm, and the magnetic flux density of the compacted composite soft magnetic material is lowered.
Further, the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O constituting the Mg-containing oxide film-coated iron powder of the present invention has a higher content of MgO on its outermost surface. Preferably, it is most preferably composed of MgO. When the outermost surface is substantially MgO, the diffusion of Fe is prevented even during firing of the green compact that has been press-molded, and contact bonding between iron powders can be prevented. This is because loss is reduced.
The Mg-Fe-O ternary oxide deposited film containing at least (Mg, Fe) O constituting the Mg-containing oxide film-coated iron powder of the present invention is a Mg-Fe-O ternary oxide deposited film comprising 10% or less of Mg relative to Mg A pseudo ternary oxide deposited film substituted with one or more of Al, Si, Ni, Mn, Zn, Cu, and Co may be used.
この発明のＭｇ含有酸化膜被覆鉄粉末は、平均粒径：５〜５００μｍの範囲内にある粉末を使用することが好ましい。その理由は、平均粒径が５μｍより小さすぎると、粉末の圧縮性が低下し、粉末の体積割合が低くなるために磁束密度の値が低下するので好ましくなく、一方、平均粒径が５００μｍより大きすぎると、粉末内部の渦電流が増大して高周波における透磁率が低下することによるものである。 As the Mg-containing oxide film-coated iron powder of the present invention, it is preferable to use a powder having an average particle size in the range of 5 to 500 μm. The reason is that if the average particle size is less than 5 μm, the compressibility of the powder is lowered, and the volume ratio of the powder is lowered, so the value of the magnetic flux density is lowered. On the other hand, the average particle size is less than 500 μm. If it is too large, the eddy current inside the powder increases and the magnetic permeability at high frequency decreases.
次に、この発明のＭｇ含有酸化膜被覆鉄粉末を使用した複合軟磁性材の製造方法を説明する。
この発明のＭｇ含有酸化膜被覆鉄粉末は通常の方法で圧粉成形し焼成することにより作製することができる。
この発明のＭｇ含有酸化膜被覆鉄粉末を用いて作製した高比抵抗を有する複合軟磁性材は、鉄粒子相とこの鉄粒子相を包囲する粒界相からなり、前記粒界相には結晶質のＭｇＯ固溶ウスタイト相を含有するＭｇ−Ｆｅ−Ｏ三元系酸化物を含むことが好ましい。
この他に、平均粒径：０．５μｍ以下の酸化ケイ素，酸化アルミニウムのうち１種または２種を０．０５〜１質量％含有し、残部をこの発明のＭｇ含有酸化膜被覆鉄粉末からなるように配合し混合して混合粉末を作製し、この混合粉末を通常の方法で圧粉成形し、焼成することにより作製することができる。この製造方法によると、この発明のＭｇ含有酸化膜被覆鉄粉末を構成する少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜は酸化ケイ素や酸化アルミニウムと反応して複合酸化物が形成され、鉄粉末の粒界に高抵抗を有する複合酸化物が介在した高比抵抗を有する複合軟磁性材が得られるとともに酸化ケイ素や酸化アルミニウムを介して焼成されるために機械的強度の優れた複合軟磁性材を製造することができる。この場合、酸化ケイ素や酸化アルミニウムが主体となって焼成されるところから保磁力を小さく保つことができ、したがって、ヒステリシス損の少ない複合軟磁性材を製造することができる、前記焼成は、不活性ガス雰囲気または酸化性ガス雰囲気中、温度：４００〜１３００℃で行われることが好ましい。
また、この発明のＭｇ含有酸化膜被覆鉄粉末にシリカのゾルゲル（シリケート）溶液やアルミナのゾルゲル溶液などの湿式溶液を添加し混合したのち乾燥し、この乾燥した混合物を圧縮成形後、不活性ガス雰囲気または酸化性ガス雰囲気中、温度：４００〜１３００℃で焼成することにより複合軟磁性材を製造することができる。これらのこの発明のＭｇ含有酸化膜被覆鉄粉末を用いて作製した高比抵抗を有する複合軟磁性材は、鉄粒子相とこの鉄粒子相を包囲する粒界相からなり、前記粒界相には結晶質のＭｇＯ固溶ウスタイト相を含有するＭｇ−Ｆｅ−Ｏ三元系酸化物を含むことが好ましい。
Next, a method for producing a composite soft magnetic material using the Mg-containing oxide film-coated iron powder of the present invention will be described.
The Mg-containing oxide film-coated iron powder of the present invention can be produced by compacting and firing by an ordinary method.
A composite soft magnetic material having a high specific resistance produced by using the Mg-containing oxide film-coated iron powder of the present invention comprises an iron particle phase and a grain boundary phase surrounding the iron particle phase, and the grain boundary phase includes crystals. It is preferable to include a Mg—Fe—O ternary oxide containing a high-quality MgO solid solution wustite phase.
In addition, 0.05 to 1% by mass of one or two of silicon oxide and aluminum oxide having an average particle size of 0.5 μm or less is contained, and the balance is composed of the Mg-containing oxide film-coated iron powder of the present invention. The mixed powder can be prepared by mixing and mixing as described above, and the mixed powder can be compacted and fired by a conventional method. According to this manufacturing method, the Mg—Fe—O ternary oxide deposited film containing at least (Mg, Fe) O constituting the Mg-containing oxide film-coated iron powder of the present invention reacts with silicon oxide or aluminum oxide. A composite soft magnetic material having a high specific resistance in which a composite oxide is formed and a composite oxide having a high resistance intervenes in the grain boundary of iron powder is obtained, and is fired through silicon oxide or aluminum oxide. A composite soft magnetic material having excellent mechanical strength can be produced. In this case, the coercive force can be kept small from being fired mainly with silicon oxide or aluminum oxide, and thus a composite soft magnetic material with low hysteresis loss can be produced. It is preferably performed at a temperature of 400 to 1300 ° C. in a gas atmosphere or an oxidizing gas atmosphere.
In addition, a wet solution such as a silica sol-gel (silicate) solution or an alumina sol-gel solution is added to the Mg-containing oxide film-coated iron powder of the present invention, and the mixture is dried, and the dried mixture is compression-molded and then inert gas. A composite soft magnetic material can be produced by firing at a temperature of 400 to 1300 ° C. in an atmosphere or an oxidizing gas atmosphere. A composite soft magnetic material having a high specific resistance produced using these Mg-containing oxide film-coated iron powders of the present invention comprises an iron particle phase and a grain boundary phase surrounding the iron particle phase. Preferably contains a Mg—Fe—O ternary oxide containing a crystalline MgO solid solution wustite phase.
さらに、この発明のＭｇ含有酸化膜被覆鉄粉末に有機絶縁材料や無機絶縁材料、あるいは有機絶縁材料と無機絶縁材料との混合材料を混合して成形、焼成すると比抵抗および強度のさらに向上した複合軟磁性材を作製することができる。この場合、有機絶縁材料では、エポキシ樹脂やフッ素樹脂、フェノール樹脂、ウレタン樹脂、シリコーン樹脂、ポリエステル樹脂、フェノキシ樹脂、ユリア樹脂、イソシアネート樹脂、アクリル樹脂、ポリイミド樹脂，等を用いることができる。また無機絶縁材料では、リン酸鉄などのリン酸塩、各種ガラス状絶縁物、珪酸ソーダを主成分とする水ガラス、絶縁性酸化物、等を用いることができる。
また、この発明のＭｇ含有酸化膜被覆鉄粉末に、酸化硼素、酸化バナジウム、酸化ビスマス、酸化アンチモンおよび酸化モリブデンの内の１種または２種以上をＢ２Ｏ３、Ｖ２Ｏ５、Ｂｉ２Ｏ３、Ｓｂ２Ｏ３、ＭｏＯ３換算で０．０５〜１質量％を配合し混合したのち圧粉成形し、得られた圧粉成形体を温度：５００〜１０００℃で焼成することにより複合軟磁性材を作製することができる。このようにして作製した複合軟磁性材は、酸化硼素、酸化バナジウム、酸化ビスマス、酸化アンチモンおよび酸化モリブデンの内の１種または２種以上をＢ２Ｏ３、Ｖ２Ｏ５、Ｂｉ２Ｏ３、Ｓｂ２Ｏ３、ＭｏＯ３換算で０．０５〜１質量％を含有し、残部がこの発明のＭｇ含有酸化膜被覆鉄粉末からなる組成を有し、少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜と、酸化硼素、酸化バナジウム、酸化ビスマス、酸化アンチモンおよび酸化モリブデンの内の１種または２種以上とが反応した皮膜が形成される。
また、この複合軟磁性材は、酸化硼素のゾル溶液または粉末、酸化バナジウムのゾル溶液または粉末、酸化ビスマスのゾル溶液または粉末、酸化アンチモンのゾル溶液または粉末および酸化モリブデンのゾル溶液または粉末の内の１種または２種以上をＢ２Ｏ３、Ｖ２Ｏ５、Ｂｉ２Ｏ３、Ｓｂ２Ｏ３、ＭｏＯ３換算で０．０５〜１質量％、残部が前記この発明のＭｇ含有酸化膜被覆鉄粉末からなる組成となるように配合し、混合し、乾燥して前記この発明のＭｇ含有酸化膜被覆鉄粉末を酸化物乾燥ゲルまたは粉末からなる混合酸化物で被覆してなる混合酸化物被覆鉄粉末を作製し、この混合酸化物被覆鉄粉末を圧粉し、成形したのち、温度：５００〜１０００℃で焼成することにより得ることができる。これらのこの発明のＭｇ含有酸化膜被覆鉄粉末を用いて作製した高比抵抗を有する複合軟磁性材は、鉄粒子相とこの鉄粒子相を包囲する粒界相からなり、前記粒界相には結晶質のＭｇＯ固溶ウスタイト相を含有するＭｇ−Ｆｅ−Ｏ三元系酸化物を含むことが好ましい。
Furthermore, when the Mg-containing oxide film-coated iron powder of the present invention is mixed with an organic insulating material, an inorganic insulating material, or a mixed material of an organic insulating material and an inorganic insulating material, and molded and fired, a composite having further improved specific resistance and strength A soft magnetic material can be produced. In this case, as the organic insulating material, epoxy resin, fluorine resin, phenol resin, urethane resin, silicone resin, polyester resin, phenoxy resin, urea resin, isocyanate resin, acrylic resin, polyimide resin, or the like can be used. As the inorganic insulating material, phosphates such as iron phosphate, various glassy insulators, water glass mainly composed of sodium silicate, insulating oxides, and the like can be used.
In addition, one or more of boron oxide, vanadium oxide, bismuth oxide, antimony oxide, and molybdenum oxide are added to the Mg-containing oxide film-coated iron powder of the present invention as B 2 O 3 , V 2 O 5 , Bi 2. O 3, Sb 2 O 3, MoO 3 powder was molded were mixed by blending 0.05 mass% in terms of the resulting powder compact temperature composite by calcining at 500 to 1000 ° C. A soft magnetic material can be produced. The composite soft magnetic material produced in this way is composed of one or more of boron oxide, vanadium oxide, bismuth oxide, antimony oxide and molybdenum oxide, B 2 O 3 , V 2 O 5 , Bi 2 O 3. , Sb 2 O 3 , MgO 3 in terms of MoO 3 , 0.05 to 1% by mass, with the balance being composed of the Mg-containing oxide film-coated iron powder of the present invention, Mg containing at least (Mg, Fe) O A film is formed in which the —Fe—O ternary oxide deposited film reacts with one or more of boron oxide, vanadium oxide, bismuth oxide, antimony oxide, and molybdenum oxide.
Further, this composite soft magnetic material is composed of a boron oxide sol solution or powder, a vanadium oxide sol solution or powder, a bismuth oxide sol solution or powder, an antimony oxide sol solution or powder, and a molybdenum oxide sol solution or powder. 1 to 2 or more of B 2 O 3 , V 2 O 5 , Bi 2 O 3 , Sb 2 O 3 , MoO 3 in terms of 0.05 to 1% by mass, and the balance being the Mg-containing oxide film of the present invention A mixed oxide formed by mixing, drying, and coating the Mg-containing oxide film-coated iron powder of the present invention with an oxide-dried gel or a mixed oxide composed of a powder so as to have a composition composed of a coated iron powder It can be obtained by preparing a coated iron powder, compacting and molding the mixed oxide-coated iron powder, followed by firing at a temperature of 500 to 1000 ° C. A composite soft magnetic material having a high specific resistance produced using these Mg-containing oxide film-coated iron powders of the present invention comprises an iron particle phase and a grain boundary phase surrounding the iron particle phase. Preferably contains a Mg—Fe—O ternary oxide containing a crystalline MgO solid solution wustite phase.
この発明のMg含有酸化膜被覆鉄粉末を用いて作製した複合軟磁性材は高密度、高強度、高比抵抗および高磁束密度を有し、この複合軟磁性材は，高磁束密度で高周波低鉄損の特徴を有する事からこの特徴を生かした各種電磁気回路部品の材料として使用できる。前記電磁気回路部品は、磁心、電動機コア，発電機コア、ソレノイドコア、イグニッションコア、リアクトル、トランス、チョークコイルコアまたは磁気センサコアなどがある。そして、この発明のＭｇ含有酸化膜被覆鉄粉末を用いた高抵抗を有する複合軟磁性材からなる電磁気回路部品を組み込んだ電気機器には、電動機、発電機、ソレノイド、インジェクタ、電磁駆動弁、インバータ、コンバータ、変圧器、継電器、磁気センサシステム等があり、電気機器の高効率高性能化や小型軽量化を行うことができる。 The composite soft magnetic material produced using the Mg-containing oxide film-coated iron powder of the present invention has high density, high strength, high specific resistance and high magnetic flux density. This composite soft magnetic material has high magnetic flux density and low frequency. Since it has the feature of iron loss, it can be used as a material for various electromagnetic circuit components that take advantage of this feature. Examples of the electromagnetic circuit component include a magnetic core, a motor core, a generator core, a solenoid core, an ignition core, a reactor, a transformer, a choke coil core, and a magnetic sensor core. In addition, an electric device incorporating an electromagnetic circuit component made of a composite soft magnetic material having high resistance using the Mg-containing oxide film-coated iron powder of the present invention includes an electric motor, a generator, a solenoid, an injector, an electromagnetically driven valve, and an inverter. There are converters, transformers, relays, magnetic sensor systems, etc., which can improve the efficiency, performance, size and weight of electrical equipment.
この発明のＭｇ含有酸化膜被覆鉄粉末を使用して複合軟磁性材を製造すると、高比抵抗を有することから低渦電流損失を有し、さらに保磁力が低いことから低ヒステリシス損失を有する複合軟磁性材を低コスト安定して作製することができ、電気・電子産業上優れた効果をもたらすものである。 When a composite soft magnetic material is manufactured using the Mg-containing oxide film-coated iron powder of this invention, it has a low specific eddy current loss because of its high specific resistance, and a low hysteresis loss because of its low coercive force. A soft magnetic material can be produced stably at a low cost, and has an excellent effect in the electrical and electronic industries.
実施例１
原料粉末として、平均粒径：７０μｍを有し不可避不純物として硫黄を極微量含む純鉄粉末を用意し、さらに、平均粒径：５０μｍのＭｇ粉末を用意した。前記純鉄粉末を大気中、温度：２２０℃、２時間保持の条件で酸化処理することにより表面に酸化鉄膜を有する酸化処理鉄粉末を作製した。この酸化処理鉄粉末に対し先に用意したＭｇ粉末を、酸化処理鉄粉末：Ｍｇ粉末＝９９．８質量％：０．２質量％の割合で添加し混合して混合粉末を作製し、得られた混合粉末を温度：６５０℃、圧力：２．７×１０−４ＭＰａ、１時間保持したのち、さらに大気中、温度：２００℃、１時間保持することにより鉄粉末の表面に堆積膜が被覆されている本発明Ｍｇ含有酸化膜被覆鉄粉末１を作製した。本発明Ｍｇ含有酸化膜被覆鉄粉末１に形成されている堆積膜の組織を電子顕微鏡で観察し、その堆積膜の厚さと最大結晶粒径を求め、その結果を表１に示した。また、本発明Ｍｇ含有酸化膜被覆鉄粉末１の堆積膜から得られた電子線回折図形から、結晶質のＭｇＯ固溶ウスタイト相を含有することが解った。
Example 1
A pure iron powder having an average particle size of 70 μm and containing an extremely small amount of sulfur as an inevitable impurity was prepared as a raw material powder, and an Mg powder having an average particle size of 50 μm was prepared. The pure iron powder was oxidized in the atmosphere at a temperature of 220 ° C. for 2 hours to prepare an oxidized iron powder having an iron oxide film on the surface. To this oxidized iron powder, the previously prepared Mg powder was added at a ratio of oxidized iron powder: Mg powder = 99.8 mass%: 0.2 mass% to prepare a mixed powder. The mixed powder was kept at a temperature of 650 ° C. and a pressure of 2.7 × 10 −4 MPa for 1 hour, and further held in the atmosphere at a temperature of 200 ° C. for 1 hour to cover the surface of the iron powder with a deposited film. The present invention Mg-containing oxide film-coated iron powder 1 was produced. The structure of the deposited film formed on the Mg-containing oxide film-coated iron powder 1 of the present invention was observed with an electron microscope, the thickness of the deposited film and the maximum crystal grain size were determined, and the results are shown in Table 1. Further, it was found from the electron diffraction pattern obtained from the deposited film of the Mg-containing oxide film-coated iron powder 1 of the present invention that the crystalline MgO solid solution wustite phase was contained.
この本発明Ｍｇ含有酸化膜被覆鉄粉末１の表面に形成された堆積膜をＸ線光電子分光装置により分析を行い、結合エネルギーを解析したところ、少なくとも（Ｍｇ，Ｆｅ）Ｏが含まれているＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜であることが解った。さらに、鉄粉末とＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜との界面領域をオージェ電子分光装置を用いた方法により調べた結果を図１のグラフに示す。図１のグラフにおいて縦軸はオージェ電子のピーク強度を示しており、一方、横軸は被覆堆積膜のエッチング時間を示しており、エッチング時間が長いほど被覆堆積膜の深い位置を示している。図１のオージェ電子分光法で検出した硫黄濃度のグラフには硫黄濃度ピークが示されており、このグラフを見ると、エッチング時間１０〜１５分程度の堆積膜と鉄粉末との界面領域に、鉄粉末の中心部に含まれる不純物硫黄（バックグラウンド）よりも明らかにオージェ電子分光法でピークをもって硫黄が検出されていることから鉄粉末の中心部に含まれる硫黄よりも高濃度の硫黄を含む硫黄濃化層を有することが解った。 The deposited film formed on the surface of the Mg-containing oxide film-coated iron powder 1 of the present invention was analyzed by an X-ray photoelectron spectrometer, and the binding energy was analyzed. As a result, Mg containing at least (Mg, Fe) O was contained. It was found to be a —Fe—O ternary oxide deposited film. Furthermore, the graph of FIG. 1 shows the results of examining the interface region between the iron powder and the Mg—Fe—O ternary oxide deposited film by a method using an Auger electron spectrometer. In the graph of FIG. 1, the vertical axis represents the peak intensity of Auger electrons, while the horizontal axis represents the etching time of the coating deposited film, and the longer the etching time, the deeper the position of the coating deposited film. In the graph of sulfur concentration detected by Auger electron spectroscopy in FIG. 1, a sulfur concentration peak is shown. In this graph, in the interface region between the deposited film and the iron powder with an etching time of about 10 to 15 minutes, It contains sulfur at a higher concentration than the sulfur contained in the center of iron powder because sulfur is detected with a peak by Auger electron spectroscopy rather than the impurity sulfur (background) contained in the center of iron powder. It was found to have a sulfur enriched layer.
実施例２
実施例１で用意した純鉄粉末を大気中、温度：２１０℃、３時間保持の条件で酸化処理することにより表面に酸化鉄膜を有する酸化処理鉄粉末を作製した。この酸化処理鉄粉末に先に用意したＭｇ粉末を実施例１よりも多くなるように酸化処理鉄粉末：Ｍｇ粉末＝９９．５質量％：０．５質量％の割合で添加し混合して混合粉末を作製し、得られた混合粉末を温度：６７０℃、圧力：１×１０−５ＭＰａ、１時間保持したのち、さらに大気中、温度：２００℃、１時間保持することにより鉄粉末の表面に堆積膜が被覆されている本発明Ｍｇ含有酸化膜被覆鉄粉末２を作製した。この本発明Ｍｇ含有酸化膜被覆鉄粉末２の堆積膜の組織を電子顕微鏡で観察し、その堆積膜の厚みと最大結晶粒径を求め、その結果を表１に示した。また、その堆積膜から得られた電子線回折図形から、結晶質のＭｇＯ固溶ウスタイト相を含有することが解った。
さらに、この本発明Ｍｇ含有酸化膜被覆鉄粉末２の表面に形成された堆積膜をＸ線光電子分光装置により分析を行い、結合エネルギーを解析したところ、この堆積膜は少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜であること、Ｍｇ−Ｆｅ−Ｏ三元系酸化物堆積膜の最表面はＭｇＯで構成されていることが解った。さらにＭｇ、ＯおよびＦｅの濃度分布を実施例１と同様にしてオージェ電子分光装置を用いた方法により調べたところ、鉄粉末とＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜との界面領域に鉄粉末の中心部に含まれる硫黄よりも高濃度の硫黄を含む硫黄濃化層を有することが分かった。
Example 2
The oxidized iron powder having an iron oxide film on the surface was produced by oxidizing the pure iron powder prepared in Example 1 in the atmosphere at a temperature of 210 ° C. for 3 hours. To this oxidized iron powder, the previously prepared Mg powder was added and mixed at a ratio of oxidized iron powder: Mg powder = 99.5 mass%: 0.5 mass% so as to be larger than in Example 1. The powder was prepared, and the obtained mixed powder was maintained at a temperature of 670 ° C., a pressure of 1 × 10 −5 MPa for 1 hour, and further held in the atmosphere at a temperature of 200 ° C. for 1 hour, thereby the surface of the iron powder. The Mg-containing oxide film-coated iron powder 2 of the present invention coated with a deposited film was prepared. The structure of the deposited film of the Mg-containing oxide film-coated iron powder 2 of the present invention was observed with an electron microscope, the thickness of the deposited film and the maximum crystal grain size were determined, and the results are shown in Table 1. Further, it was found from the electron diffraction pattern obtained from the deposited film that it contained a crystalline MgO solid solution wustite phase.
Furthermore, when the deposited film formed on the surface of the Mg-containing oxide film-coated iron powder 2 of the present invention was analyzed by an X-ray photoelectron spectrometer and the binding energy was analyzed, this deposited film was at least (Mg, Fe) O. It was found that the Mg—Fe—O ternary oxide deposited film containing Mg and the outermost surface of the Mg—Fe—O ternary oxide deposited film are composed of MgO. Further, when the concentration distribution of Mg, O and Fe was examined by a method using an Auger electron spectrometer in the same manner as in Example 1, it was found in the interface region between the iron powder and the Mg—Fe—O ternary oxide deposited film. It was found to have a sulfur enriched layer containing a higher concentration of sulfur than the sulfur contained in the center of the iron powder.
実施例３
実施例１で用意した純鉄粉末を大気中、温度：２２０℃、１．５時間保持の条件で酸化処理することにより表面に酸化鉄膜を有する酸化処理鉄粉末を作製した。この酸化処理鉄粉末に先に用意したＭｇ粉末を実施例１よりも多くなるように酸化処理鉄粉末：Ｍｇ粉末＝９９．７質量％：０．３質量％の割合で添加し混合して混合粉末を作製し、得られた混合粉末を温度：６４０℃、圧力：１×１０−４ＭＰａ、１時間保持したのち、さらに大気中、温度：２００℃、１．５時間保持することにより鉄粉末の表面に堆積膜が被覆されている本発明Ｍｇ含有酸化膜被覆鉄粉末３を作製した。この堆積膜の組織を電子顕微鏡で観察し、その厚みおよび最大結晶粒径を表１に示した．
この本発明Ｍｇ含有酸化膜被覆鉄粉末３の表面に形成された堆積膜をＸ線光電子分光装置により分析を行い、結合エネルギーを解析したところ、少なくとも（Ｍｇ，Ｆｅ）Ｏを含むＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜であること、このＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜の最表面はＭｇＯで構成されていることが解った。さらに、このＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜のＭｇ、ＯおよびＦｅの濃度分布をオージェ電子分光装置を用いて実施例１と同じ方法により調べたところ、鉄粒子とＭｇ−Ｆｅ−Ｏ三元系酸化物堆積膜との界面領域に鉄粉末の中心部に含まれる硫黄よりも高濃度の硫黄を含む硫黄濃化層を有することが分かった。
Example 3
The pure iron powder prepared in Example 1 was oxidized in the atmosphere at a temperature of 220 ° C. and maintained for 1.5 hours to prepare an oxidized iron powder having an iron oxide film on the surface. To this oxidized iron powder, the previously prepared Mg powder was added and mixed at a ratio of oxidized iron powder: Mg powder = 99.7 mass%: 0.3 mass% so as to be larger than in Example 1. A powder was prepared, and the obtained mixed powder was maintained at a temperature of 640 ° C. and a pressure of 1 × 10 −4 MPa for 1 hour, and then further maintained in the atmosphere at a temperature of 200 ° C. for 1.5 hours. The Mg-containing oxide film-coated iron powder 3 of the present invention having a deposited film coated on its surface was prepared. The structure of the deposited film was observed with an electron microscope, and the thickness and maximum crystal grain size are shown in Table 1.
The deposited film formed on the surface of the Mg-containing oxide film-coated iron powder 3 of the present invention was analyzed by an X-ray photoelectron spectrometer, and the binding energy was analyzed. As a result, Mg—Fe— containing at least (Mg, Fe) O was obtained. It was found that it was an O ternary oxide deposited film, and that the outermost surface of this Mg—Fe—O ternary oxide deposited film was composed of MgO. Furthermore, when the Mg, O, and Fe concentration distribution of this Mg—Fe—O ternary oxide deposited film was examined by the same method as in Example 1 using an Auger electron spectrometer, the iron particles and Mg—Fe— It was found that a sulfur-concentrated layer containing sulfur having a higher concentration than sulfur contained in the central portion of the iron powder was present in the interface region with the O ternary oxide deposited film.
実施例１〜３で得られた本発明Ｍｇ含有酸化膜被覆鉄粉末１〜３を金型に入れ、プレス成形して縦：５５ｍｍ、横：１０ｍｍ、厚さ：５ｍｍの寸法を有する板状圧粉体および外径：３５ｍｍ、内径：２５ｍｍ、高さ：５ｍｍの寸法を有するリング形状圧粉体を成形し、得られた圧粉体を窒素雰囲気中、温度：５００℃、３０分保持の条件で焼成を行い、板状およびリング状焼成体からなる複合軟磁性材を作製し、この板状焼成体からなる複合軟磁性材の比抵抗を測定してその結果を表１に示し、さらにリング状焼成体からなる複合軟磁性材に巻き線を施し、磁束密度、保磁力、並びに磁束密度１．５Ｔ、周波数５０Ｈｚの時の鉄損および磁束密度１．０Ｔ、周波数４００Ｈｚの時の鉄損などの磁気特性を測定し、それらの結果を表１に示した。また実施例２で得られた本発明Ｍｇ含有酸化膜被覆鉄粉末２を用いた複合軟磁性材を透過電子顕微鏡で観察したところ、鉄粒子相とこの鉄粒子相を包囲する粒界相が観察され、前記粒界相から得られた電子線回折図形から、粒界相には結晶質のＭｇＯ固溶ウスタイト相を含有するＭｇ−Ｆｅ−Ｏ三元系酸化物を含むことが解った。 The Mg-containing oxide film-coated iron powders 1 to 3 of the present invention obtained in Examples 1 to 3 are placed in a mold and pressed to form a plate-like pressure having dimensions of 55 mm in length, 10 mm in width, and 5 mm in thickness. Powder and outer diameter: 35 mm, inner diameter: 25 mm, height: a ring-shaped green compact having a size of 5 mm was molded, and the obtained green compact was maintained in a nitrogen atmosphere at a temperature of 500 ° C. for 30 minutes. The composite soft magnetic material made of a plate-like and ring-like fired body was prepared, the specific resistance of the composite soft magnetic material made of this plate-like fired body was measured, and the result is shown in Table 1. A composite soft magnetic material made of a sintered product is wound, and magnetic flux density, coercive force, and iron loss at a magnetic flux density of 1.5 T and a frequency of 50 Hz, and an iron loss at a magnetic flux density of 1.0 T and a frequency of 400 Hz, etc. The magnetic properties were measured and the results are shown in Table 1.Moreover, when the composite soft magnetic material using the Mg-containing oxide film-coated iron powder 2 of the present invention obtained in Example 2 was observed with a transmission electron microscope, an iron particle phase and a grain boundary phase surrounding the iron particle phase were observed. From the electron diffraction pattern obtained from the grain boundary phase, it was found that the grain boundary phase contains a Mg—Fe—O ternary oxide containing a crystalline MgO solid solution wustite phase.
従来例１
実施例１で用意した純鉄粉末の表面にＭｇ含有フェライト層を化学的に形成した従来酸化物被覆鉄粉末１を作製し、この従来酸化物被覆鉄粉末１を金型に入れ、プレス成形して縦：５５ｍｍ、横：１０ｍｍ、厚さ：５ｍｍの寸法を有する板状圧粉体および外径：３５ｍｍ、内径：２５ｍｍ、高さ：５ｍｍの寸法を有するリング形状圧粉体を成形し、得られた圧粉体を窒素雰囲気中、温度：５００℃、３０分保持の条件で焼成を行い、板状およびリング状焼成体からなる複合軟磁性材を作製し、板状焼成体からなる複合軟磁性材の比抵抗を測定してその結果を表１に示し、さらにリング状焼成体からなる複合軟磁性材に巻き線を施し、磁束密度、保磁力、並びに磁束密度１．５Ｔ、周波数５０Ｈｚの時の鉄損および磁束密度１．０Ｔ、周波数４００Ｈｚの時の鉄損などの磁気特性を測定し、それらの結果を表１に示した。
Conventional Example 1
A conventional oxide-coated iron powder 1 in which an Mg-containing ferrite layer is chemically formed on the surface of the pure iron powder prepared in Example 1 is prepared, and this conventional oxide-coated iron powder 1 is placed in a mold and press-molded. A plate-shaped green compact having dimensions of 55 mm in length, 10 mm in width, and 5 mm in thickness, and a ring-shaped green compact having dimensions of 35 mm in outer diameter, 25 mm in inner diameter, and 5 mm in height are obtained. The obtained green compact is fired in a nitrogen atmosphere at a temperature of 500 ° C. for 30 minutes to produce a composite soft magnetic material comprising a plate-like and ring-like fired body, and a composite soft magnetic material comprising a plate-like fired body. The specific resistance of the magnetic material was measured and the results are shown in Table 1. Further, the composite soft magnetic material made of the ring-shaped fired body was wound, and the magnetic flux density, coercive force, magnetic flux density 1.5T, frequency 50 Hz Iron loss and magnetic flux density 1.0T, frequency 4 The magnetic properties such as iron loss when 0Hz was measured. The results are shown in Table 1.
表１に示される結果から、本発明Ｍｇ含有酸化膜被覆鉄粉末１〜３を使用して作製した複合軟磁性材は、従来酸化物被覆鉄粉末１を使用して作製した複合軟磁性材従来複合軟磁性材と比べて、密度については大差は無いが、本発明Ｍｇ含有酸化膜被覆鉄粉末１〜３を使用して作製した複合軟磁性材は、従来酸化物被覆鉄粉末１を使用して作製した複合軟磁性材に比べて、磁束密度が高く、保磁力が小さく、さらに比抵抗が格段に高く、そのため鉄損が格段に小さく、特に周波数が大きくなるほど鉄損が小さくなるなどの特性を有することから、本発明Ｍｇ含有酸化膜被覆鉄粉末１〜３は従来酸化物被覆鉄粉末１と比べて一層優れた特性を有する複合軟磁性材を提供することができる軟磁性原料粉末であることが分かる。 From the results shown in Table 1, the composite soft magnetic material produced using the Mg-containing oxide film-coated iron powders 1 to 3 of the present invention is the conventional composite soft magnetic material produced using the oxide-coated iron powder 1 Compared to the composite soft magnetic material, the density is not much different, but the composite soft magnetic material produced using the Mg-containing oxide film-coated iron powders 1 to 3 of the present invention uses the conventional oxide-coated iron powder 1. Compared with the composite soft magnetic material produced in this way, the magnetic flux density is high, the coercive force is low, and the specific resistance is remarkably high, so that the iron loss is remarkably small, especially as the frequency increases, the iron loss decreases. Therefore, the Mg-containing oxide film-coated iron powders 1 to 3 of the present invention are soft magnetic raw material powders that can provide a composite soft magnetic material having more excellent characteristics than the conventional oxide-coated iron powder 1. I understand that.
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| US11/814,603 US9269481B2 (en) | 2005-01-25 | 2005-11-02 | Iron powder coated with Mg-containing oxide film |
| EP05805498A EP1852199B1 (en) | 2005-01-25 | 2005-11-02 | Mg-CONTAINING OXIDE COATED IRON POWDER |
| CA002598842A CA2598842A1 (en) | 2005-01-25 | 2005-11-02 | Iron powder coated with mg-containing oxide film |
| PCT/JP2005/020204 WO2006080121A1 (en) | 2005-01-25 | 2005-11-02 | Mg-CONTAINING OXIDE COATED IRON POWDER |
| EP10172637.0A EP2248617B1 (en) | 2005-01-25 | 2005-11-02 | Iron powder coated with Mg-containing oxide film |
| EP12172935.4A EP2502689B8 (en) | 2005-01-25 | 2005-11-02 | Iron powder coated with Mg-containing oxide film |
| CN2005800491939A CN101142044B (en) | 2005-01-25 | 2005-11-02 | Iron powder coated with mg-containing oxide film |
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