JP2010206046A - Magnet molding and method of making the same - Google Patents
Magnet molding and method of making the same Download PDFInfo
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- JP2010206046A JP2010206046A JP2009051562A JP2009051562A JP2010206046A JP 2010206046 A JP2010206046 A JP 2010206046A JP 2009051562 A JP2009051562 A JP 2009051562A JP 2009051562 A JP2009051562 A JP 2009051562A JP 2010206046 A JP2010206046 A JP 2010206046A
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- Powder Metallurgy (AREA)
- Hard Magnetic Materials (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
Description
本発明は、磁石成形体及びその製造方法に関する。より詳細にいえば、特に高い電気抵抗を有し、モータ等に組み込んだ場合の渦電流損失を低減してモータ効率を向上可能とする磁石成形体、及びその製造方法に関する。 The present invention relates to a magnet molded body and a manufacturing method thereof. More specifically, the present invention relates to a magnet molded body that has a particularly high electrical resistance and that can reduce eddy current loss when incorporated in a motor or the like and improve motor efficiency, and a method for manufacturing the same.
従来より、モータ等に搭載される永久磁石としては、安価なフェライト磁石が多用されているが、近年では、モータの小型化や高性能化に伴い、より高性能な希土類磁石の使用量が年々増加する傾向にある。 Conventionally, inexpensive ferrite magnets have been widely used as permanent magnets mounted on motors and the like, but in recent years, with the miniaturization and high performance of motors, the use of higher performance rare earth magnets has been increasing year by year. It tends to increase.
しかし、希土類磁石は金属磁石であるため電気抵抗が低く、モータに組みこんだ場合に、渦電流損失が増大し、モータの効率を低下させるという問題がある。 However, since the rare earth magnet is a metal magnet, its electric resistance is low, and when incorporated in a motor, there is a problem that eddy current loss increases and the efficiency of the motor decreases.
そこで、希土類磁石自体の電気抵抗を高めて、このような問題を解決しようとする各種の提案がなされている。 Therefore, various proposals have been made to solve such problems by increasing the electric resistance of the rare earth magnet itself.
例えば、ＳｉＯ２及び／またはＡｌ２Ｏ３からなる粒子状酸化物を磁石粉末に結着した構造を有する希土類磁石が開示されている（特許文献１）。 For example, a rare earth magnet having a structure in which a particulate oxide made of SiO 2 and / or Al 2 O 3 is bound to a magnet powder is disclosed (Patent Document 1).
しかしながら、これらの酸化物は、磁石特性を損なうことから、モータの出力が高い場合には適用が困難となるという問題がある。 However, since these oxides impair the magnet characteristics, there is a problem that application becomes difficult when the output of the motor is high.
そこで本発明は、電気抵抗及び磁気特性の双方に優れた磁石成形体及びその製造方法を提供することを目的とする。 Then, an object of this invention is to provide the magnet molded object excellent in both an electrical resistance and a magnetic characteristic, and its manufacturing method.
本発明に係る磁石成形体及びその製造方法は、絶縁皮膜で被覆された磁石粉末の粒径が１５０μｍ超の粒子を断面の面積率として５０％以上含有する点に特徴を有する。 The magnet molded body and the method for producing the same according to the present invention are characterized in that the magnetic powder coated with an insulating film contains particles having a particle size of more than 150 μm in an area ratio of 50% or more.
本発明によれば、磁石粉末の粒径を制御することにより、電気抵抗及び磁気特性の双方に優れた磁石成形体を得ることが可能となる。 According to the present invention, it is possible to obtain a magnet molded article excellent in both electric resistance and magnetic characteristics by controlling the particle size of the magnet powder.
以下、添付した図面を参照しながら、本発明の実施形態を説明する。なお、図面の説明において同一の要素には同一の符号を付し、重複する説明を省略する。また、図面の寸法比率は、説明の都合上誇張されており、実際の比率とは異なる場合がある。ここで、本明細書における「％」は、特記しない限り、「質量％」を意味するものとする。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios. Here, “%” in this specification means “mass%” unless otherwise specified.
［第１実施形態］
本発明の第１実施形態に係る磁石成形体は、磁石粉末と、前記磁石粉末を覆う絶縁皮膜とを含む磁石成形体であって、前記絶縁皮膜で被覆された前記磁石粉末の粒径が１５０μｍ超の粒子を断面の面積率として５０％以上有する。
[First Embodiment]
The magnet molded body according to the first embodiment of the present invention is a magnet molded body including magnet powder and an insulating film covering the magnet powder, and the particle diameter of the magnet powder coated with the insulating film is 150 μm. It has 50% or more of super-particles as the area ratio of the cross section.
本明細書において、まず、「磁石粉末」とは、不定形の単磁区粒子（ドメイン）の集合体であって一般に入手可能な磁石粒子の粉末を意味する。次に、「磁石成形前駆体」とは、磁石粉末に皮膜を施した構造体を意味する。次に、「磁石成形体」とは、磁石成形前駆体を加熱加圧成形（焼結を含む）して得られた、本実施形態に係る目的物を意味する。 In the present specification, first, “magnet powder” means a magnet particle powder that is an aggregate of amorphous single domain particles (domains) and is generally available. Next, “magnet molding precursor” means a structure in which a film is applied to magnet powder. Next, the “magnet molded body” means an object according to the present embodiment obtained by heating and pressing (including sintering) a magnet molding precursor.
上述のように、電気抵抗及び磁気特性の双方に優れた、出力の高いモータ等にも好適に使用可能な磁石が強く求められている。しかしながら、従来技術はいずれもかかる要求を到底満足するものではない。 As described above, there is a strong demand for a magnet that is excellent in both electric resistance and magnetic characteristics and that can be suitably used in a motor with high output. However, none of the conventional techniques satisfy such a requirement.
例えば、磁石特性を損なうことのない絶縁材料として、希土類主体の酸化物が見出され、磁石特性の低下を最小限に抑制しつつ、高い電気抵抗を有する希土類磁石が開示されている（特開２００４−３１９９５５号公報）。かような高い電気抵抗を有する磁石の製造に際して、原料となる希土類磁石の粉末を圧密化することになる。具体的には、圧密時に単純に絶縁物を混合する手法や、磁石粉末に絶縁材を被覆した原料粉末（磁石成形前駆体）を圧密化する手法が用いられる。しかし、上記の手法では、磁石粉末間に分散する酸化物の分布状況にばらつきが生じ、高い電気抵抗を安定して実現させることは非常に困難である。また、高い電気抵抗を安定して実現でき渦電流損失を低減することが可能な希土類磁石や、絶縁物質として希土類酸化物を用いることを特徴とする希土類磁石の製造方法が開示されている（特開２００４−３１７８１号公報、特開２００７−８８１０８号公報）。 For example, a rare earth-based oxide has been found as an insulating material that does not impair the magnet characteristics, and a rare earth magnet having a high electrical resistance while minimizing the deterioration of the magnet characteristics is disclosed (Japanese Patent Laid-Open No. 2000-260867). 2004-319955). When manufacturing a magnet having such a high electric resistance, the rare earth magnet powder as a raw material is compacted. Specifically, a method of simply mixing an insulator at the time of compaction or a method of compacting a raw material powder (magnet molding precursor) obtained by coating a magnetic powder with an insulating material is used. However, in the above method, the distribution of oxides dispersed between the magnet powders varies, and it is very difficult to stably realize high electrical resistance. There are also disclosed a rare earth magnet capable of stably realizing high electrical resistance and reducing eddy current loss, and a method for producing a rare earth magnet characterized by using a rare earth oxide as an insulating material (special feature). JP 2004-31781 A, JP 2007-88108 A).
上記の磁石は、磁石粉末を希土類酸化物で被覆したものであるため、電気抵抗を向上させる点では、一見すると比較的有益なものと考えられる。しかし、本発明者らが検討したところ、加熱成形工程で絶縁皮膜と磁石粉末との間で化学反応が積極的に進行してしまい、得られる磁石成型体の磁気特性を低減させたり、必ずしも電気抵抗を十分に発現できない問題が生じる場合があった。一方、化学反応を抑制するような製造条件は非常に限定されたものであるため、従来技術ではかかる条件から容易に外れやすく、磁気特性の劣化を非常に引き起こしやすいという問題があった。 Since the magnet is a magnet powder coated with a rare earth oxide, it is considered relatively useful at first glance in terms of improving electrical resistance. However, as a result of investigations by the present inventors, a chemical reaction actively proceeds between the insulating film and the magnet powder in the heat forming process, and the magnetic properties of the obtained magnet molded body are reduced or not necessarily electrically. There may be a problem that the resistance cannot be sufficiently developed. On the other hand, since the production conditions for suppressing the chemical reaction are very limited, the conventional technique has a problem that it is easily deviated from such conditions, and the magnetic characteristics are very easily deteriorated.
本発明者らは、以上の課題を解決すべく、不可避的に起こる上記の化学反応に起因した磁気特性の劣化を最小限に抑えるため、鋭意研究を重ねた。その結果、原料である磁石粉末の粒径という条件に着目することによって、上記の課題を解決しうることを見出した。さらに詳細な検討を重ねたところ、所定の粒径以上の磁石粉末を所定以上の断面面積率で含有させてなる磁石粉末という構成に辿り着いたのである。換言すれば、磁石粉末の粒径に着目することなく製造した磁石成形体の場合、粒度分布が広範な範囲に亘る磁石粉末から構成されるため、上記の課題を解決することはできないことを見出したのである。なお、前記「粒度分布が広範な範囲に亘る磁石粉末」とは、様々な粒径（例えば１〜５００μｍ程度）の磁石粒子を全体に亘って有意な断面面積率で有する磁石粉末と言い換えることもできる。 In order to solve the above-mentioned problems, the present inventors have conducted intensive studies in order to minimize the deterioration of magnetic properties caused by the above-described chemical reaction that inevitably occurs. As a result, it has been found that the above problem can be solved by paying attention to the condition of the particle size of the magnet powder as the raw material. As a result of further detailed studies, the inventors have reached a configuration of a magnet powder in which a magnet powder having a predetermined particle size or more is contained at a predetermined cross-sectional area ratio. In other words, in the case of a magnet molded body manufactured without paying attention to the particle size of the magnet powder, it is found that the above problem cannot be solved because the particle size distribution is composed of the magnet powder over a wide range. It was. In addition, the above-mentioned “magnet powder having a wide particle size distribution” may be rephrased as a magnet powder having magnet particles having various particle sizes (for example, about 1 to 500 μm) with a significant cross-sectional area ratio throughout. it can.
そして、上記の構成により、磁気特性の劣化する磁石粉末が大幅に低減され、磁気特性を維持した電気抵抗の高い希土類磁石が得られることを見出し、本発明を完成するに至った。以下、本発明の技術的な原理について詳細に説明する。 And it discovered that the magnet powder in which magnetic characteristics deteriorated by said structure was reduced significantly, and obtained the rare earth magnet with the high electrical resistance which maintained the magnetic characteristics, and came to complete this invention. Hereinafter, the technical principle of the present invention will be described in detail.
絶縁物質と接する磁石粉末の表面では、不可避的に化学反応が起こり、磁気特性の劣化が生じうる。ここで、原料である磁石粉末の粒度を小さくすると、表面積が増加すると同時に、磁石粉末内部において上記の化学反応の起こっていない領域（以下、「健全領域」ともいう）が相対的に減少することになる。磁石粉末内部のかかる健全領域が一定の割合を下回ると、磁石としての磁気特性が全体的に大幅に低減してしまう。そのため、バルク磁石全体としても、急激に磁気特性の劣化が生じうる。 On the surface of the magnetic powder in contact with the insulating material, a chemical reaction inevitably occurs, and the magnetic properties may be deteriorated. Here, when the particle size of the magnet powder as the raw material is reduced, the surface area is increased, and at the same time, the area where the above chemical reaction does not occur (hereinafter also referred to as “healthy area”) is relatively decreased. become. When such a healthy region inside the magnet powder falls below a certain ratio, the magnetic characteristics as a magnet are greatly reduced as a whole. For this reason, the magnetic properties of the bulk magnet as a whole can be rapidly deteriorated.
一方、所定の粒径以上の磁石粉末を所定以上の断面面積率で含有する磁石粉末という構成の場合、バルク磁石内部の磁石粉末の表面積を低減することができる。そのため、化学反応によって磁気特性の劣化する領域が低減することに加えて、バルク磁石を構成する個々の磁石粉末においても、磁石粉末内部の健全領域が増加する。そのため、たとえ磁石粉末の表面の一部が磁気特性を消失しても、磁石粉末自体としては、磁気特性を維持することができると共に、磁石粉末の集合体であるバルク磁石も特段の磁気特性の劣化を生じずに目的物（製品）を得ることができる。 On the other hand, in the case of a configuration of magnet powder containing magnet powder having a predetermined particle size or more with a cross-sectional area ratio of a predetermined value or more, the surface area of the magnet powder inside the bulk magnet can be reduced. Therefore, in addition to the reduction of the region where the magnetic properties are deteriorated due to the chemical reaction, the healthy region inside the magnet powder also increases in the individual magnet powders constituting the bulk magnet. Therefore, even if a part of the surface of the magnet powder loses its magnetic properties, the magnetic powder itself can maintain the magnetic properties, and the bulk magnet, which is an aggregate of the magnet powder, also has special magnetic properties. An object (product) can be obtained without causing deterioration.
本発明に係る磁石成形体は、以上の技術的な原理に基づくものであって、磁石粉末の５０％以上（断面の面積率）が粒径１５０μｍ超の粒子で構成され、それらの個々の磁石粉末が希土類酸化物で被覆されたことを特徴とする。 The magnet molded body according to the present invention is based on the above technical principle, and 50% or more (area ratio of the cross section) of the magnet powder is composed of particles having a particle diameter of more than 150 μm, and individual magnets thereof. The powder is coated with a rare earth oxide.
図１は、本実施形態における磁石成形前駆体１の構成を模式的に示す断面図である。図１を見ると、磁石粉末２（このうち、断面の面積率５０％以上が粒径１５０μｍ超である）を絶縁皮膜３が被覆している。換言すれば、磁石粉末２全体で、断面面積率５０％以上が１５０μｍ超である。以下、本実施形態の各構成要素について詳細に説明する。 FIG. 1 is a cross-sectional view schematically showing a configuration of a magnet molding precursor 1 in the present embodiment. When FIG. 1 is seen, the insulating film 3 has coat | covered the magnet powder 2 (Of these, the area ratio of 50% or more of a cross section is a particle size exceeding 150 micrometers). In other words, the cross-sectional area ratio of 50% or more exceeds 150 μm in the entire magnet powder 2. Hereinafter, each component of the present embodiment will be described in detail.
＜磁石粉末＞
磁石粉末２は、永久磁石であって固体磁石である限り、特に制限されることはない。磁石粉末２の素材としては、例えば、磁鉄鉱（マグネタイト）、クロム鋼、高コバルト鋼、アルニコ、フェライト、希土類または希土類鉄などが挙げられる。このうち、強力な磁気特性が得られ、高性能の磁石が得られる観点からいえば、磁石粉末２は希土類磁石からなることが好ましい。なお、本明細書において、「希土類磁石からなる」とは、正確には「実質的に希土類磁石からなる」ことを意味する。換言すれば、本実施形態による磁石成形体の性能が有意に損なわれない範囲であれば、磁石粉末は希土類磁石以外の成分を含有してもよい。
<Magnet powder>
The magnet powder 2 is not particularly limited as long as it is a permanent magnet and a solid magnet. Examples of the raw material of the magnet powder 2 include magnetite (magnetite), chromium steel, high cobalt steel, alnico, ferrite, rare earth or rare earth iron. Among these, from the viewpoint of obtaining strong magnetic properties and obtaining a high-performance magnet, the magnet powder 2 is preferably made of a rare earth magnet. In the present specification, “consisting of rare earth magnets” means “consisting essentially of rare earth magnets”. In other words, the magnet powder may contain components other than the rare earth magnet as long as the performance of the magnet compact according to the present embodiment is not significantly impaired.
希土類は、磁鉄鉱（マグネタイト）、クロム鋼や高コバルト鋼などと比較して、モータ用磁石として使用する際の磁気特性が強い。また、希土類は、アルニコ磁石などと比較すると、磁気特性が同等に優れている。さらに、フェライトなどの酸化物磁石は、酸化物であることに起因して、高抵抗化手法を用いることなく十分な電気抵抗を有することから、本発明による高抵抗化手法は、必ずしも必要でない場合が多い。そのため、本発明による高抵抗化手法は、希土類磁石を用いることにより、最も高性能の磁石を得ることが可能となる。 Rare earths have stronger magnetic properties when used as magnets for motors than magnetite, chrome steel, high cobalt steel, and the like. Rare earths are equally superior in magnetic properties as compared to alnico magnets. Further, since an oxide magnet such as ferrite has sufficient electric resistance without using a high resistance method due to being an oxide, the high resistance method according to the present invention is not always necessary. There are many. Therefore, the high resistance method according to the present invention can obtain the highest performance magnet by using a rare earth magnet.
上記の希土類磁石からなる磁石粉末（以下、「希土類磁石粉末」ともいう）としては、以下に制限されることはないが、Ｎｄ−Ｆｅ−Ｂ（ネオジム−鉄−ホウ素）系磁石、Ｓｍ−Ｃｏ（サマリウム−コバルト）系磁石などが挙げられる。希土類磁石は、これらＮｄ−Ｆｅ−Ｂ系磁石などの構成要素が１種単独からなっても、２種以上からなってもよい。また、各構成要素における組成比、例えばＮｄ−Ｆｅ−Ｂ系磁石におけるＮｄ、Ｆｅ及びＢの組成比については、特に制限されることはない。数例を挙げると、本実施形態による希土類磁石は、単一の組成比を有するＮｄ−Ｆｅ−Ｂ系磁石からなってもよく、２種以上の異なる組成比を有するＮｄ−Ｆｅ−Ｂ系磁石からなってもよい。あるいは、単一のまたは２種以上の異なる組成比を有するＮｄ−Ｆｅ−Ｂ系磁石に加えて、Ｓｍ−Ｃｏ系磁石からなってもよい。したがって、上記の「２種以上」の構成要素とは、先に例示した、「２種以上の異なる組成比を有するＮｄ−Ｆｅ−Ｂ系磁石」、及び「単一のまたは２種以上の異なる組成比を有するＮｄ−Ｆｅ−Ｂ系磁石に加えて、Ｓｍ−Ｃｏ系磁石」の双方の意味を含む。 The magnet powder made of the rare earth magnet (hereinafter also referred to as “rare earth magnet powder”) is not limited to the following, but is an Nd—Fe—B (neodymium-iron-boron) magnet, Sm—Co. Examples include (samarium-cobalt) magnets. The rare earth magnet may be composed of one or more components such as Nd—Fe—B magnets. Further, the composition ratio in each component, for example, the composition ratio of Nd, Fe, and B in the Nd—Fe—B magnet is not particularly limited. For example, the rare earth magnet according to the present embodiment may be composed of an Nd—Fe—B magnet having a single composition ratio, and may be an Nd—Fe—B magnet having two or more different composition ratios. It may consist of. Or in addition to the Nd-Fe-B type magnet which has a single or 2 or more types of different composition ratios, you may consist of a Sm-Co type magnet. Therefore, the above-mentioned “two or more types” of the constituent elements are the “Nd—Fe—B magnets having two or more different composition ratios” and “single or two or more different types” as exemplified above. In addition to the Nd—Fe—B magnet having a composition ratio, the meaning of both “Sm—Co magnet” is included.
希土類磁石粉末として、好ましくは、永久磁石の中でも高い磁気特性を有するという観点より、Ｎｄ−Ｆｅ−Ｂ系磁石を主成分とする。より好ましくは、ＨＤＤＲ法によって製造されたＮｄ−Ｆｅ−Ｂ系磁石や、熱間アップセット（熱間後方押出し加工）処理によって配向処理したＮｄ−Ｆｅ−Ｂ系磁石から作製した粉末を主成分とする。かかる場合、従来の（焼結用）磁石粉末とは異なり、絶縁皮膜の被覆処理を施しても、磁気特性が損なわれることが殆どないため有利である。なお、前記ＨＤＤＲ法とは、Ｈｙｄｒｏｇｅｎａｔｉｏｎ Ｄｅｃｏｍｐｏｓｉｔｉｏｎ Ｄｅｓｏｒｐｔｉｏｎ Ｒｅｃｏｍｂｉｎａｔｉｏｎ法を指す。 The rare earth magnet powder is preferably composed mainly of an Nd—Fe—B magnet from the viewpoint of having high magnetic properties among permanent magnets. More preferably, a powder produced from an Nd-Fe-B magnet manufactured by the HDDR method or an Nd-Fe-B magnet magnet oriented by hot upset (hot backward extrusion) processing is used as a main component. To do. In this case, unlike the conventional (sintering) magnet powder, even if the insulating film is coated, the magnetic properties are hardly impaired, which is advantageous. The HDDR method refers to the Hydrogen Deposition Decomposition Recombination method.
上記のなかでも、経済的に優れ、熱間加工によるバルク化にも耐えうる磁石であるという理由から、ＨＤＤＲ処理を施したＮｄ−Ｆｅ−Ｂ系磁石を主成分とすることが特に好ましい。そして、ＨＤＤＲ処理によって作製されたＮｄ−Ｆｅ−Ｂ系磁石粉末を用いた場合、一層高い磁気特性が得られうる。ＨＤＤＲ処理によって作製された磁石粉末は、バルク化時に加圧することにより、通常の焼結磁石より低温での成形が可能なため、過剰な液相が発現しない低温で高密度な成形体を得ることができるため、優れた磁気特性が得られうる。 Among these, it is particularly preferable that the main component is an Nd—Fe—B magnet subjected to HDDR treatment because it is economically excellent and can withstand bulking by hot working. And when the Nd-Fe-B system magnet powder produced by HDDR process is used, a still higher magnetic characteristic can be acquired. Magnet powder produced by HDDR treatment can be molded at a lower temperature than ordinary sintered magnets by applying pressure during bulking, so that a compact body can be obtained at a low temperature that does not exhibit an excessive liquid phase. Therefore, excellent magnetic properties can be obtained.
また、磁石粉末２が希土類磁石からなる場合に、アップセット処理によって製造されたＭＱパウダー（ネオジウム系磁性粉末）や、ボンド磁石用に用いられるナノコンポジット磁石粉末を使用してもよい。かかる場合も、通常の焼結磁石用の磁石粉末とは異なり、絶縁皮膜の被覆処理を施しても、磁気特性を発現できるため、有利である。 Further, when the magnet powder 2 is made of a rare earth magnet, MQ powder (neodymium magnetic powder) manufactured by an upset process or nanocomposite magnet powder used for a bonded magnet may be used. Even in such a case, unlike ordinary magnet powders for sintered magnets, magnetic properties can be expressed even if an insulating coating is applied, which is advantageous.
以下、希土類磁石粉末についてさらに詳細に説明する。 Hereinafter, the rare earth magnet powder will be described in more detail.
希土類磁石粉末は、強磁性の主相及び他の成分からなる。例えば、希土類磁石がＮｄ−Ｆｅ−Ｂ系磁石である場合には、主相はＮｄ２Ｆｅ１４Ｂ相である。したがって、磁石粉末２がＮｄ２Ｆｅ１４Ｂを主成分とすることは経済面及び磁気特性の面から特に好適である。前記希土類磁石粉末として、磁場配向処理をしない等方性希土類磁石を製造するためのものと、磁場配向処理をする異方性希土類磁石を製造するためのものとが挙げられる。しかし、異方性磁石の方が強磁力性など磁石特性に優れている点より、前記希土類磁石粉末は、異方性希土類磁石を製造可能な磁石粉末であることが好ましい。 The rare earth magnet powder is composed of a ferromagnetic main phase and other components. For example, when the rare earth magnet is an Nd—Fe—B based magnet, the main phase is an Nd 2 Fe 14 B phase. Therefore, it is particularly preferable that the magnet powder 2 contains Nd 2 Fe 14 B as a main component from the viewpoints of economy and magnetic properties. Examples of the rare earth magnet powder include one for producing an isotropic rare earth magnet not subjected to magnetic field orientation treatment and one for producing an anisotropic rare earth magnet subjected to magnetic field orientation treatment. However, the anisotropic magnet is preferably a magnet powder capable of producing an anisotropic rare earth magnet because the anisotropic magnet is superior in magnetic properties such as strong magnetic properties.
ここで、磁石粉末１の粒径の範囲は、磁石粉末２がＮｄ−Ｆｅ−Ｂ系のＨＤＤＲ磁石粉末である場合に磁気特性の低下を効果的に抑制できる観点より、５０μｍを超えて５００μｍ以下が好ましい。より好ましくは１００μｍを超えて５００μｍ以下であり、さらに好ましくは１５０μｍを超えて５００μｍ以下である。なお、本明細書において、「磁石粉末１の粒径」は、篩いで分けたものである。そして、本明細書で用いる篩いは、東京スクリーン社のステンレス製試験用ふるい（ＪＩＳ Ｚ ８８０１）である。 Here, the range of the particle size of the magnet powder 1 is more than 50 μm and 500 μm or less from the viewpoint of effectively suppressing the decrease in magnetic properties when the magnet powder 2 is an Nd—Fe—B HDDR magnet powder. Is preferred. More preferably, it is more than 100 micrometers and 500 micrometers or less, More preferably, it is more than 150 micrometers and 500 micrometers or less. In the present specification, the “particle diameter of the magnet powder 1” is divided by a sieve. The sieve used in this specification is a stainless steel test sieve (JIS Z 8801) manufactured by Tokyo Screen.
ここで、本明細書における「主成分」とは、含量として最も多い成分を必ずしも意味するものではなく、本願所望の効果を得る上で主要かつ不可欠な成分を意味する。上記主成分を具体的な数値で表すと、希土類磁石粉末１００体積％に対して、Ｎｄ−Ｆｅ−Ｂ系の合金相の濃度は、７５体積％以上であることが好ましく、８５〜１００体積％であることがより好ましい。７５体積％以上の場合、得られる希土類磁石の磁石特性の向上や、製造コストの低減などが達成できる。なお、Ｎｄ−Ｆｅ−Ｂ系の合金相以外の成分として、配向性や保磁力向上のため、Ｃｏ、Ｔｂ、Ｄｙ、Ｚｎ、Ａｌ、Ｃｕ、Ｚｒなどを含有してもよい。 Here, the “main component” in the present specification does not necessarily mean the most content component, but means a main and indispensable component for obtaining the desired effect of the present application. When the main component is represented by specific numerical values, the concentration of the Nd—Fe—B alloy phase is preferably 75% by volume or more with respect to 100% by volume of the rare earth magnet powder, and is 85 to 100% by volume. It is more preferable that In the case of 75 volume% or more, improvement of the magnet characteristics of the obtained rare earth magnet, reduction of manufacturing cost, etc. can be achieved. In addition, as components other than the Nd—Fe—B alloy phase, Co, Tb, Dy, Zn, Al, Cu, Zr, and the like may be contained in order to improve orientation and coercive force.
本明細書における「Ｎｄ−Ｆｅ−Ｂ系磁石」とは、Ｎｄ及び／またはＦｅの一部が他の元素で置換されている形態をも包含する概念である。Ｎｄは、その一部または全体がプラセオジム（Ｐｒ）に置換されていてもよく、また、Ｎｄの一部がテルビウム（Ｔｂ）、ジスプロシウム（Ｄｙ）、ホルミウム（Ｈｏ）等の他の希土類元素で置換されていてもよい。置換にはこれらの一方のみを用いてもよく、双方を用いてもよい。置換は、元素合金の配合量を調整することによって行うことができる。かような置換によって、Ｎｄ−Ｆｅ−Ｂ系磁石の保磁力向上を図ることができる。置換されるＮｄの量は、Ｎｄに対して、０．０１〜２０ａｔｏｍ％であることが好ましい。かような範囲でＮｄが置換されると、置換による効果を十分に確保しつつ、残留磁束密度を高レベルで維持することが可能である。 The “Nd—Fe—B magnet” in the present specification is a concept including a form in which a part of Nd and / or Fe is substituted with another element. Nd may be partly or wholly substituted with praseodymium (Pr), and part of Nd may be substituted with other rare earth elements such as terbium (Tb), dysprosium (Dy), holmium (Ho), etc. May be. Only one of these may be used for substitution, or both may be used. The substitution can be performed by adjusting the compounding amount of the element alloy. By such replacement, the coercive force of the Nd—Fe—B magnet can be improved. The amount of Nd to be substituted is preferably 0.01 to 20 atom% with respect to Nd. When Nd is replaced in such a range, it is possible to maintain the residual magnetic flux density at a high level while sufficiently securing the effect of the replacement.
一方、Ｆｅは、Ｃｏ等の他の遷移金属で置換されていてもよい。かような置換によって、Ｎｄ−Ｆｅ−Ｂ系磁石のキュリー温度（Ｔｃ）を上昇させ、磁石の耐熱性を向上させることができる。置換されるＦｅの量は、Ｆｅ １００ａｔｏｍ％に対して、０．０１〜３０ａｔｏｍ％であることが好ましく、０．１〜５ａｔｏｍ％であることがより好ましい。かような範囲でＦｅが置換されると、置換による効果を十分に確保しつつ、保磁力の低下が抑制されうる。 On the other hand, Fe may be substituted with other transition metals such as Co. By such substitution, the Curie temperature (Tc) of the Nd—Fe—B magnet can be increased and the heat resistance of the magnet can be improved. The amount of Fe to be substituted is preferably 0.01 to 30 atom% and more preferably 0.1 to 5 atom% with respect to 100 atom% of Fe. When Fe is substituted in such a range, a decrease in coercive force can be suppressed while sufficiently securing the effect of the substitution.
上記に加えて、例えば、ＨＤＤＲ処理により作製された、前記「異方性希土類磁石を製造可能な希土類磁石粉末」を原料として異方性磁石を製造する場合には、希土類磁石粉末における主相の配向を揃えることが容易となる。なお、前記主相は、Ｎｄ−Ｆｅ−Ｂ系磁石においてはＮｄ２Ｆｅ１４Ｂ相を指す。 In addition to the above, for example, when an anisotropic magnet is manufactured using the “rare earth magnet powder capable of manufacturing an anisotropic rare earth magnet” produced by HDDR processing as a raw material, the main phase of the rare earth magnet powder It becomes easy to align the orientation. Incidentally, the main phase, in the Nd-Fe-B based magnet refers to a Nd 2 Fe 14 B phase.
磁石粉末２の含有量は、１００質量％の磁石成形前駆体１に対して、８０〜９８質量％であることが好ましく、８５〜９８質量％であることがより好ましく、９０〜９８質量％であることがさらに好ましい。かかる範囲内の場合、磁石成分の正味の密度を高くすることができ、磁束密度及び最大エネルギー積に優れた磁石を得ることができる。 The content of the magnet powder 2 is preferably 80 to 98% by mass, more preferably 85 to 98% by mass, and 90 to 98% by mass with respect to 100% by mass of the magnet molding precursor 1. More preferably it is. In such a range, the net density of the magnet component can be increased, and a magnet excellent in magnetic flux density and maximum energy product can be obtained.
図２は、酸化ジスプロシウム（Ｄｙ２Ｏ３）からなる絶縁皮膜で被覆した希土類磁石粉末を熱間成形により圧密化してなる磁石成型体の保磁力と、希土類磁石粉末の粒径との関係を示すグラフである。ここで、前記粒径は、原料である希土類磁石粉末（原料磁粉）を７５μｍ、１５０μｍ、２５０μｍの各メッシュを有する篩いを用いて分級したものである。 FIG. 2 shows the relationship between the coercive force of a magnet molded body obtained by compacting a rare earth magnet powder coated with an insulating film made of dysprosium oxide (Dy 2 O 3 ) by hot forming and the particle size of the rare earth magnet powder. It is a graph. Here, the particle size is obtained by classifying rare earth magnet powder (raw material magnetic powder), which is a raw material, using a sieve having meshes of 75 μm, 150 μm, and 250 μm.
また、図３は、１５０μｍ超の粒径の磁石粉末と７５μｍ以下の粒径の磁石粉末とを混合した場合の、細粒粒子の断面面積率による保磁力の変化を示したグラフである。図３を見れば、当該断面面積率が０．４５未満程度で特性（保磁力）が急落し、当該断面面積率が０．５程度に変曲点の存することが分かる。ここで、図中の横軸（細粒粒子の断面面積率）について説明する。絶縁物質（絶縁皮膜形成用）による被覆処理を行わない磁石粉末（被覆処理無）については、光学顕微鏡観察による断面観察からは粒径が不明瞭であるため、代わりに、混合した磁石粉末の割合を示している。他方、絶縁被覆処理を行った磁石粉末（被覆処理有）については、光学顕微鏡観察による断面観察を行い、５０倍の視野を５箇所以上測定し、細粒粒子の断面面積率を測定した。粒径は、長径と短径の平均値から算出し、１５０μｍ超のものを粗大粒、１５０μｍ以下のものを細粒とし、分解能の制約で粒径が測定困難なものは対象外とした。図４は、点算法による粗大粒及び細粒の（断面）面積率の算出方法を示す図である。図４に示すように、粒径の計測は光学顕微鏡を用いた断面観察により行い、５０倍の組織写真を撮影し、画像解析処理装置で約４０倍に拡大し、０．５ｍｍのメッシュ間隔による点算法により算出した。 FIG. 3 is a graph showing the change in coercive force due to the cross-sectional area ratio of fine particles when a magnet powder having a particle size of more than 150 μm and a magnet powder having a particle size of 75 μm or less are mixed. As can be seen from FIG. 3, when the cross-sectional area ratio is less than about 0.45, characteristics (coercive force) drop sharply, and the cross-section area ratio has an inflection point of about 0.5. Here, the horizontal axis (cross-sectional area ratio of fine particles) in the figure will be described. For magnet powder that is not coated with an insulating material (for insulating film formation) (without coating treatment), the particle size is not clear from cross-sectional observation by optical microscope observation. Is shown. On the other hand, about the magnetic powder (with coating process) which performed the insulation coating process, the cross-sectional observation by optical microscope observation was performed, the 50 times visual field was measured five or more places, and the cross-sectional area ratio of the fine particle was measured. The particle size was calculated from the average value of the major axis and the minor axis, and those with a particle size of more than 150 μm were coarse particles and those with a particle size of 150 μm or less were fine particles. FIG. 4 is a diagram illustrating a method for calculating the area ratio of coarse and fine grains (cross section) by a point calculation method. As shown in FIG. 4, the particle size is measured by cross-sectional observation using an optical microscope, a 50-fold tissue photograph is taken, magnified approximately 40 times by an image analysis processing apparatus, and a 0.5 mm mesh interval is used. It was calculated by the point calculation method.
ここで、本願における「点算法」は、ＪＩＳ Ｇ０５５５として鋼中の介在物の面積率を計測する手法として定められているものを採用する。本手法は、金属組織観察による相比の計測手法としても代表的な計測方法のひとつとして用いられており、オーステナイトステンレス鋼中のフェライト量の定量化や分散強化型合金の分散相の定量化に使用されている。ＪＩＳ Ｇ ０５５５による方法では、顕微鏡の接眼鏡に縦横それぞれ２０本の格子をもつガラス板を挿入して、介在物によって占められた格子点の中心を数えるもので、被検面を無作為に移動し、その度ごとに同じ手順を繰り返すものである。一般に、この移動する回数（視野数）を６０（最小でも３０以上）とするように定められ、介在物の占める面積百分率ｄは次式により判定される。 Here, as the “point calculation method” in the present application, a method defined as a method for measuring the area ratio of inclusions in steel as JIS G0555 is adopted. This method is also used as one of the typical measurement methods as a phase ratio measurement method by observing the metal structure. It is used to quantify the amount of ferrite in austenitic stainless steel and the dispersion phase of dispersion strengthened alloys. in use. In the method according to JIS G 0555, a glass plate having 20 grids in both vertical and horizontal directions is inserted into the eyepiece of the microscope, and the center of the grid points occupied by the inclusions is counted. However, the same procedure is repeated each time. Generally, the number of times of movement (number of visual fields) is determined to be 60 (30 or more at the minimum), and the area percentage d occupied by inclusions is determined by the following equation.
ただし、ｎ：介在物によって占められた総格子点中心数、ｐ：ガラス盤の格子点数、ｆ：視野数である。 Where n is the total number of lattice point centers occupied by inclusions, p is the number of lattice points on the glass board, and f is the number of fields of view.
なお、ここでいう格子点中心とは各格子線の交点の中心で数学的な点を意味するものである。また、一般的に、この際の誤差範囲は視野数を大にすれば小さくなることが知られている。 Here, the lattice point center means a mathematical point at the center of the intersection of each lattice line. In general, it is known that the error range at this time decreases as the number of fields of view increases.
本実施形態では、上記手法に鑑みて、光学顕微鏡で断面を観察し、粗大粒子（粗大粒）と細粒粒子（細粒）との断面面積率を点算法から測定し、細粒の断面面積率を求めた。即ち、５０倍の視野で観察した観察像に縦横５００μｍ間隔に相当する格子線を設け、格子点の中心に該当する粒子が粗大粒と細粒のどちらに該当するかを判別する手法で計測した。視野の数は、観察する試料の形状によって異なるが、各試料とも合計の格子点が１２０００点以上になる様に視野数を決定した。これは、２０×２０の格子点で３０視野以上に相当する。なお、粒径は、図４に示すように、まず、光学顕微鏡による断面観察から５０倍の組織写真を撮影した。続いて、画像解析処理装置で約４０倍に拡大して計測し、長径と短径の平均値から算出し、１５０μｍ超のものを粗大粒、１５０μｍ以下のものを細粒とし、分解能の制約で粒径が測定困難なものは細粒に含めた。図４には、例として１５０μｍ超の粗大粒に相当すると判断した格子点に「●」印を示した。 In the present embodiment, in view of the above method, the cross section is observed with an optical microscope, the cross-sectional area ratio of coarse particles (coarse particles) and fine particles (fine particles) is measured from a point calculation method, and the cross-sectional area of the fine particles The rate was determined. That is, measurement was performed by a method in which a lattice line corresponding to an interval of 500 μm in length and breadth was provided in an observation image observed with a 50 × field of view, and whether a particle corresponding to the center of the lattice point corresponds to a coarse particle or a fine particle. . The number of fields of view varies depending on the shape of the sample to be observed, but the number of fields of view was determined so that the total number of lattice points for each sample was 12,000 or more. This is equivalent to 30 fields of view or more with 20 × 20 lattice points. As shown in FIG. 4, first, a 50-fold structure photograph was taken from a cross-sectional observation with an optical microscope. Subsequently, the image analysis processing device is magnified by about 40 times, and is calculated from the average value of the major axis and minor axis. The coarser particles are larger than 150 μm, the smaller particles are smaller than 150 μm, and the resolution is limited. Those whose particle size was difficult to measure were included in the fine granules. In FIG. 4, “●” marks are shown at lattice points that are judged to correspond to coarse grains of more than 150 μm as an example.
なお、図２及び図３において、保磁力は、２５０μｍ超の粒子のみを用いた場合の値を「１００％」とする相対値で表している。即ち、図２及び図３中の縦軸（保磁力相対値）は、２５０μｍ超の粒径からなる原料磁粉の保磁力を「１００％」としたときの、粒径の各範囲における相対値を示す。 In FIGS. 2 and 3, the coercive force is expressed as a relative value where the value when only particles larger than 250 μm are used is “100%”. That is, the vertical axis (coercive force relative value) in FIG. 2 and FIG. 3 represents the relative value in each range of the particle size when the coercive force of the raw magnetic powder having a particle size of more than 250 μm is “100%”. Show.
図２及び図３には、高抵抗化のための絶縁被覆処理を行わない磁石粉末をバルク化した場合についても併せて示している。この場合、絶縁物質と磁石粉末との化学反応は起こらないため、不可避的に発生する表面酸化の程度でしか保磁力が低下しない。そのため、保磁力の劣化は観察されない。また、通常、ＨＤＤＲ処理した磁石粉末においては、粒径が過度に大きいと、内部の集合組織の配向度が低下するため、１００〜１５０μｍ程度の粒子を用いることが好適であると考えられる。しかし、本実施形態のように粒径の大きいものは、絶縁物質（絶縁皮膜形成用）で被覆せずに使用する場合、配向度に劣る結果として最大エネルギー積が低くなる等、却って磁気特性が低下し得る。そのため、従来、このような、比較的大きな粒径の割合が高い磁石粉末は、使用が避けられてきた。 FIG. 2 and FIG. 3 also show the case where the magnet powder that is not subjected to the insulation coating process for increasing the resistance is bulked. In this case, since a chemical reaction between the insulating substance and the magnet powder does not occur, the coercive force is reduced only by the degree of surface oxidation that inevitably occurs. Therefore, no deterioration of the coercive force is observed. In general, in the HDDR-treated magnet powder, if the particle size is excessively large, the degree of orientation of the internal texture decreases, so it is considered preferable to use particles of about 100 to 150 μm. However, a material having a large particle size as in the present embodiment has a magnetic property that is not covered with an insulating material (for forming an insulating film) and has a lower maximum energy product as a result of inferior orientation. Can be reduced. For this reason, conventionally, such a magnetic powder having a relatively large ratio of particle size has been avoided.
しかし、これらの図から明らかなように、バルク磁石の保磁力は用いる磁石粉末の粒径によって異なる。１５０μｍ以下の粒子を用いると劣化が著しく、また保磁力が良好な粗い粒子を用いた場合でも、磁気特性が劣化する１５０μｍ以下の粒子を５０％以上（断面の面積率）含有すると、バルク磁石全体の磁気特性が損なわれることを見出した。 However, as is clear from these figures, the coercive force of the bulk magnet varies depending on the particle size of the magnet powder used. When particles with a particle size of 150 μm or less are used, deterioration is significant, and even when coarse particles with good coercive force are used, if the particles with a particle size of 150 μm or less with a deteriorated magnetic property are contained by 50% or more (area ratio of the cross section), the entire bulk magnet It was found that the magnetic properties of were impaired.
本実施形態において、１５０μｍ超の粒径を有する磁石粉末が断面の面積率として５０％以上あれば、保磁力を８５％以上に保持できる。好ましくは６０％以上の断面面積率を有するものであれば、保磁力を９０％以上に保持することができる。 In this embodiment, if the magnet powder having a particle size of more than 150 μm has a cross-sectional area ratio of 50% or more, the coercive force can be maintained at 85% or more. If the cross-sectional area ratio is preferably 60% or more, the coercive force can be maintained at 90% or more.
＜絶縁皮膜＞
磁石粉末２は、実質上完全に絶縁皮膜３によって被覆されていることが好ましい。なぜなら、磁石粉末２同士の間に絶縁皮膜３が実質上、常に存在するような状態の下では、磁石成形体の電気抵抗が有意に高まるからである。
<Insulating film>
It is preferable that the magnet powder 2 is substantially completely covered with the insulating film 3. This is because the electrical resistance of the magnet compact is significantly increased under the condition that the insulating coating 3 is substantially always present between the magnet powders 2.
絶縁皮膜３は、絶縁性材料から構成される。絶縁皮膜３は、特に制限されることはないが、希土類酸化物を含むことが好ましく、希土類酸化物からなることがより好ましい。前記希土類酸化物として、好ましくは下記式（Ｉ）： The insulating film 3 is made of an insulating material. The insulating film 3 is not particularly limited, but preferably includes a rare earth oxide, and more preferably includes a rare earth oxide. As the rare earth oxide, preferably the following formula (I):
で表される組成を有する希土類酸化物が挙げられる。希土類酸化物は、非晶質であってもよいし、結晶質であってもよい。式（Ｉ）において、Ｒはイットリウム（Ｙ）を含んでもよい希土類元素を表す。Ｒの具体例としては、上記イットリウム（Ｙ）の他、ジスプロシウム（Ｄｙ）、スカンジウム（Ｓｃ）、ランタン（Ｌａ）、セリウム（Ｃｅ）、プラセオジム（Ｐｒ）、ネオジム（Ｎｄ）、プロメチウム（Ｐｍ）、サマリウム（Ｓｍ）、ユウロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）、テルビウム（Ｔｂ）、ホルミウム（Ｈｏ）、エルビウム（Ｅｒ）、ツリウム（Ｔｍ）、イッテルビウム（Ｙｂ）、ルテチウム（Ｌｕ）が挙げられる。希土類酸化物を構成する希土類元素は、１種単独の元素からなってもよく、２種以上の元素からなってもよい。なかでも、絶縁皮膜３はジスプロシウム（Ｄｙ）及び／またはテルビウム（Ｔｂ）の酸化物を含むことが好ましい。なぜなら、希土類磁石粉末との反応を抑制できるため、優れた磁気特性（保磁力）と高い電気抵抗性とを共に得ることができるためである。経済性（コスト面）で見れば、Ｄｙの酸化物を必須に含むことがより好ましい。 The rare earth oxide which has a composition represented by these is mentioned. The rare earth oxide may be amorphous or crystalline. In the formula (I), R represents a rare earth element that may contain yttrium (Y). Specific examples of R include yttrium (Y), dysprosium (Dy), scandium (Sc), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), Examples include samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). The rare earth element constituting the rare earth oxide may be composed of one kind of element, or may be composed of two or more kinds of elements. Especially, it is preferable that the insulating film 3 contains the oxide of dysprosium (Dy) and / or terbium (Tb). This is because the reaction with the rare earth magnet powder can be suppressed, so that both excellent magnetic properties (coercivity) and high electrical resistance can be obtained. From the viewpoint of economy (cost), it is more preferable that an oxide of Dy is essential.
このように、希土類酸化物は、希土類元素の酸化物でさえあれば、混合物であっても複合酸化物であっても特に限定されない。ここで、磁気特性の低下を一層抑制する観点からは、下記式（ＩＩ）： As described above, the rare earth oxide is not particularly limited as long as it is an oxide of a rare earth element, whether it is a mixture or a complex oxide. Here, from the viewpoint of further suppressing the decrease in magnetic properties, the following formula (II):
で表される組成を有する希土類酸化物を含むことがさらに好ましい。なお、上記式（ＩＩ）中、Ｒ’及びＲ”は、それぞれテルビウム（Ｔｂ）及びジスプロシウム（Ｄｙ）を示し、Ｘは０を超えて１以下の値を意味する。 More preferably, a rare earth oxide having a composition represented by: In the formula (II), R ′ and R ″ represent terbium (Tb) and dysprosium (Dy), respectively, and X represents a value exceeding 0 and 1 or less.
絶縁皮膜３が希土類酸化物を十分量含有すると、希土類磁石における絶縁性が十分に確保され、高抵抗の希土類磁石が得られる。さらに、磁石粉末２との反応性が低く、且つ磁気特性に優れた磁石成形体を得ることができる。希土類酸化物の具体的な構成元素や組成については上述した通りである。なお、絶縁皮膜３の構成成分としては、絶縁性物質であれば特に制限されることはなく、希土類酸化物以外にも、例えば、金属酸化物、フッ化物またはガラスなどがありうる。 When the insulating film 3 contains a sufficient amount of rare earth oxide, sufficient insulation is ensured in the rare earth magnet, and a high resistance rare earth magnet is obtained. Furthermore, a magnet molded body having low reactivity with the magnet powder 2 and excellent magnetic properties can be obtained. The specific constituent elements and composition of the rare earth oxide are as described above. The constituent component of the insulating film 3 is not particularly limited as long as it is an insulating material, and may include, for example, a metal oxide, a fluoride, or glass in addition to the rare earth oxide.
なお、絶縁皮膜３が希土類酸化物からなる場合であっても、これ以外の不純物や製造工程に起因する反応生成物、未反応残存物、微小な空孔等の存在が生じうることは不可避的にありうる。これらの不純物の混入量は、導電性や磁気特性の観点からは少ないほど好ましい。ただし、絶縁皮膜３における希土類酸化物の含有量が上記した範囲内であれば、製品としての磁石の磁気特性にとって実質的に問題ない。 In addition, even when the insulating film 3 is made of a rare earth oxide, it is unavoidable that other impurities, reaction products, unreacted residues, minute vacancies, and the like due to the manufacturing process may occur. It is possible. The amount of these impurities mixed is preferably as small as possible from the viewpoint of conductivity and magnetic properties. However, if the content of the rare earth oxide in the insulating film 3 is within the above-described range, there is substantially no problem with the magnetic properties of the magnet as a product.
絶縁皮膜３の含有量については特に制限はないが、磁石成形体１００質量％に対して、好ましくは１〜２０質量％であり、より好ましくは３〜１０質量％である。特に、絶縁皮膜３の含有量が１質量％以上であれば、磁石における高い絶縁性が確保され、一層高抵抗の磁石成形体が提供される。また、絶縁皮膜３の含有量が２０質量％以下であれば、磁石粉末２の含有量が相対的に減少することに伴う磁気特性の低下を効果的に防止できる。 Although there is no restriction | limiting in particular about content of the insulating film 3, Preferably it is 1-20 mass% with respect to 100 mass% of magnet molded bodies, More preferably, it is 3-10 mass%. In particular, when the content of the insulating film 3 is 1% by mass or more, high insulation in the magnet is ensured, and a magnet molded body with higher resistance is provided. Moreover, if content of the insulating film 3 is 20 mass% or less, the fall of the magnetic characteristic accompanying the content of the magnet powder 2 reducing relatively can be prevented effectively.
一方、絶縁皮膜３は、希土類元素の有機錯体を熱分解して得られた酸化物を含むことも好ましい。希土類元素の有機錯体を原料として熱分解により得られる絶縁皮膜は、ＸＰＳ（光電子分光法）等を用いて希土類元素の結合形態を解析すると、酸素との結合（酸化物）に混じって炭素や炭化水素との結合が確認できる。酸化物以外の上記の結合は、少なければ少ないほど好ましいものと言える。しかし、磁石粉末１の磁気特性を維持する観点からいえば、相変態を防止し粒成長を抑制するために、通常、熱分解温度を完全な酸化物の形成に必要な温度にまで高めることは困難である。したがって、不可避的に残留する不純物や残留物が、絶縁皮膜３中に存在してしまう。 On the other hand, the insulating film 3 preferably contains an oxide obtained by thermally decomposing an organic complex of rare earth elements. An insulating film obtained by pyrolysis using a rare earth element organic complex as a raw material is analyzed by XPS (photoelectron spectroscopy) or the like. Bonding with hydrogen can be confirmed. It can be said that the smaller the number of bonds other than the oxide, the better. However, from the viewpoint of maintaining the magnetic properties of the magnet powder 1, in order to prevent phase transformation and suppress grain growth, it is usually not possible to increase the thermal decomposition temperature to that required for complete oxide formation. Have difficulty. Accordingly, impurities and residues that inevitably remain exist in the insulating film 3.
このため、完全な酸化物からなる絶縁皮膜と比較した場合、現実の絶縁皮膜は少なからず電気抵抗が劣化していることが考えられる。しかし、絶縁皮膜は、モータ内の電磁誘導により発生する起電力に起因した、磁石粉末１内の誘導電流が、その内部で還流するように、粒子間での経路を阻害すればよい。したがって、本実施形態における絶縁皮膜３は、完全な酸化物からなる絶縁皮膜が有すると考えられる値ほど高い絶縁性を必要とせず、２〜１０桁程度低くなった値でも十分に本願所望の目的を果たし、効果を発揮することができる。 For this reason, when compared with an insulating film made of a perfect oxide, it is conceivable that the electrical resistance of the actual insulating film is degraded. However, the insulating film should just inhibit the path | route between particle | grains so that the induced current in the magnet powder 1 resulting from the electromotive force which generate | occur | produces by the electromagnetic induction in a motor circulates in the inside. Therefore, the insulating film 3 in the present embodiment does not require as high an insulating property as a value considered to have an insulating film made of a complete oxide, and a desired value of the present application can be sufficiently achieved even with a value lower by about 2 to 10 digits. Can be effective.
［第２実施形態］
本発明の第２実施形態は、上記第１実施形態の磁石成形体の製造方法に係る。以下、本実施形態を詳細に説明するが、上記第１実施形態で説明した事項と重複するものについては、既に説明した事項がそのまま本実施形態に引用されるため、ここでは説明を省略する。
[Second Embodiment]
2nd Embodiment of this invention concerns on the manufacturing method of the magnet molded object of the said 1st Embodiment. In the following, the present embodiment will be described in detail. However, since the matters already described in the first embodiment are directly referred to in the present embodiment, the description thereof is omitted here.
本実施形態に係る希土類磁石の製造方法は、絶縁皮膜で被覆された磁石粉末（磁石成形前駆体）を高温下で加熱加圧成形することを特徴とする。 The method for producing a rare earth magnet according to the present embodiment is characterized in that magnet powder (magnet molding precursor) coated with an insulating film is heated and pressed at a high temperature.
本実施形態における希土類磁石は、上記したように、希土類酸化物で被覆された希土類磁石粉末を、さらに結着用の希土類酸化物（上記希土類酸化物と同一物質であっても異なる物質であってもよい）と共に混合することにより混合体としてもよい。そして、これを高温加圧成形することによって製造することができる。ここで、磁石粉末（希土類磁石粉末など）に絶縁性材料（希土類酸化物など）を被覆させる際、物理気相蒸着（ＰＶＤ）法及び化学気相蒸着（ＣＶＤ）法などによる蒸着法、並びに磁石粉末に塗布した希土類錯体を酸化させる方法などを用いることができる。 As described above, the rare earth magnet in the present embodiment is obtained by further combining a rare earth magnet powder coated with a rare earth oxide with a rare earth oxide (which may be the same material as the rare earth oxide or a different material). It is good also as a mixture by mixing with (good). And it can manufacture by carrying out high temperature pressure molding of this. Here, when magnet powder (such as rare earth magnet powder) is coated with an insulating material (such as rare earth oxide), vapor deposition methods such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), and magnets A method of oxidizing the rare earth complex applied to the powder can be used.
上記の蒸着法によれば、高純度の希土類酸化物からなる理想的な絶縁皮膜を形成できる反面、コストが高くなる虞がある。絶縁皮膜で被覆する工程は、希土類錯体を含む溶液を磁石粉末に塗布する段階と、前記希土類錯体を酸化させて希土類酸化物とする段階とからなる方法を採用することが好ましい。即ち、上記の２段階からなる方法を用いることにより、溶液を用いることによって均一な膜厚の塗布被膜（絶縁皮膜）が得られる。加えて、磁石粉末に対する密着性及び酸化物に対する濡れ性に優れた絶縁皮膜が得られる。 According to the above vapor deposition method, an ideal insulating film made of a high-purity rare earth oxide can be formed, but the cost may increase. The step of coating with an insulating film preferably employs a method comprising a step of applying a solution containing a rare earth complex to a magnet powder and a step of oxidizing the rare earth complex to form a rare earth oxide. That is, by using the above two-step method, a coating film (insulating film) having a uniform thickness can be obtained by using a solution. In addition, an insulating film excellent in adhesion to the magnet powder and wettability to the oxide can be obtained.
上記の希土類錯体としては、希土類元素を含有し、軟磁性合金粉末に被膜を形成することができるものであれば特に限定されるものではなく、例えば、Ｒ１Ｌ３で表される希土類錯体を用いることができる。ここで、Ｒ１はイットリウム（Ｙ）を含んでもよい希土類元素を表す。Ｒ１の具体例としては、上記イットリウム（Ｙ）の他、ジスプロシウム（Ｄｙ）、スカンジウム（Ｓｃ）、ランタン（Ｌａ）、セリウム（Ｃｅ）、プラセオジム（Ｐｒ）、ネオジム（Ｎｄ）、プロメチウム（Ｐｍ）、サマリウム（Ｓｍ）、ユウロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）、テルビウム（Ｔｂ）、ホルミウム（Ｈｏ）、エルビウム（Ｅｒ）、ツリウム（Ｔｍ）、イッテルビウム（Ｙｂ）、ルテチウム（Ｌｕ）が挙げられる。なかでも好ましくはＤｙ及び／またはＴｂである。 The rare earth complex is not particularly limited as long as it contains a rare earth element and can form a film on a soft magnetic alloy powder. For example, a rare earth complex represented by R 1 L 3 is used. Can be used. Here, R 1 represents a rare earth element that may contain yttrium (Y). Specific examples of R 1 include yttrium (Y), dysprosium (Dy), scandium (Sc), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and promethium (Pm). , Samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Of these, Dy and / or Tb are preferred.
一方、Ｌは有機物の配位子であって、（ＣＯ（ＣＯ３）ＣＨＣＯ（ＣＨ３））−、（ＣＯ（Ｃ（ＣＨ３）３）ＣＨＣＯ（ＣＣＨ３））−、（ＣＯ（Ｃ（ＣＨ３）３）ＣＨＣＯ（Ｃ３Ｆ７））−、及び（ＣＯ（ＣＦ３）ＣＨＣＯ（ＣＦ３））−、並びにβ−ジケトナトイオン等の陰イオンの有機基を表す。なお、例えば、（ＣＯ（ＣＯ３）ＣＨＣＯ（ＣＨ３））−における「−」は結合手を表し、ここで列挙した他の化合物についても同様である。 On the other hand, L is an organic ligand, and is (CO (CO 3 ) CHCO (CH 3 ))-, (CO (C (CH 3 ) 3 ) CHCO (CCH 3 ))-, (CO (C ( CH 3 ) 3 ) CHCO (C 3 F 7 ))-and (CO (CF 3 ) CHCO (CF 3 ))-and an anionic organic group such as β-diketonato ion. For example, “-” in (CO (CO 3 ) CHCO (CH 3 )) — represents a bond, and the same applies to the other compounds listed here.
また、絶縁皮膜の形成の際には、メタノール、エタノール、ｎ−プロパノールや２−プロパノール等のアルコール類、アセトン、メチルエチルケトンやジエチルケトン等のケトン類、またはヘキサン等を用いてもよい。Ｒ１Ｌ３を溶解させ得るこれらの低沸点溶媒に溶解させて塗布することができる。 In forming the insulating film, alcohols such as methanol, ethanol, n-propanol and 2-propanol, ketones such as acetone, methyl ethyl ketone and diethyl ketone, hexane, and the like may be used. R 1 L 3 can be dissolved and applied in these low boiling solvents.
本実施形態により得られる磁石成形体は、上記のように、磁石粉末２に絶縁皮膜３を被覆して得られる磁石成形前駆体１を、加熱加圧成形（燒結を含む）して得られる磁石成形体である。そして、絶縁皮膜（絶縁酸化物）で被覆された磁石粉末の粒径として、１５０μｍ超の粒子を断面の面積率として５０％以上有する磁石成形体である点を特徴とする。絶縁酸化物により被覆された磁石粉末の粒子間に絶縁酸化物（絶縁皮膜形成用及び／または結着用）が介在することによって、磁石粉末同士が結着した構造を採る。上記の磁石成形体が希土類磁石である場合を例に説明すると、前記希土類磁石は、希土類酸化物からなる絶縁皮膜で被覆された希土類磁石粉末を結着用の希土類酸化物と共に高温で加圧成形することによって得られるものである。上記の磁石粉末の被覆層または被覆された磁石粉末間に介在する結着部を形成する希土類酸化物については、１種単独であってもよいし、２種以上の混合物または複合酸化物であってもよい。 As described above, the magnet molded body obtained by this embodiment is a magnet obtained by heat-pressing (including sintering) the magnet molding precursor 1 obtained by coating the magnetic powder 2 with the insulating film 3. It is a molded body. The magnet powder covered with an insulating film (insulating oxide) is characterized in that it is a magnet molded body having particles having a cross-sectional area ratio of 50% or more as a particle size of more than 150 μm. A structure in which magnet powders are bonded together by interposing insulating oxides (for insulating film formation and / or binding) between magnet powder particles coated with insulating oxides is adopted. The case where the magnet molded body is a rare earth magnet will be described as an example. The rare earth magnet is formed by pressing a rare earth magnet powder coated with an insulating film made of a rare earth oxide at a high temperature together with a rare earth oxide for binding. Can be obtained. The rare earth oxide forming the binder layer interposed between the magnet powder coating layer or the coated magnet powder may be one kind alone, a mixture of two or more kinds or a complex oxide. May be.
本実施形態により得られる磁石成形体は、従来の焼結磁石とは異なり、圧密体を得るために加圧下で加熱処理（加熱加圧処理）することを特徴とする。加圧と加熱は同時に行っても別工程で行ってもよいが、加圧時の温度は通常、５００〜８００℃となるように調節する。従来の焼結磁石の場合には、磁気特性を得るために１０００℃以上での加熱による液相焼結が不可避である。これに対し、本実施形態は、磁石粉末の表面に絶縁皮膜を形成するための絶縁物質を塗布することを特徴の１つとするため、従来の焼結磁石のような液相焼結による磁気特性は比較的発現しにくい。そのため、既に磁気特性を備えた磁石粉末を用いることが好ましい。そのような磁石粉末の加熱温度は５００〜８００℃とすることが好ましい。８００℃以下で加熱すると、粒成長などのミクロレベルでの組織変化の発生を効果的に抑制でき、磁気特性の劣化を防止しうる。一方、５００℃以上で加熱すれば、粒子の変形が十分となって、密度の大きな成形体が得られうる。より好ましくは６００〜７５０℃であり、さらに好ましくは６２０〜７２０℃である。なお、加圧をせずに緻密化する場合、加熱温度が５００〜８００℃では低すぎ、１０００℃以上での加熱が必要となりうる。そのため、加圧成形を施すことによって圧密化を促進することが好ましい。なお、加圧する際の圧力としては、緻密化を促進するという観点より、好ましくは２００〜６００ＭＰａであり、より好ましくは３００〜５００ＭＰａである。 Unlike the conventional sintered magnet, the magnet molded body obtained by the present embodiment is characterized in that it is subjected to heat treatment (heat pressure treatment) under pressure in order to obtain a compacted body. Pressurization and heating may be performed simultaneously or in separate steps, but the temperature at the time of pressurization is usually adjusted to 500 to 800 ° C. In the case of a conventional sintered magnet, liquid phase sintering by heating at 1000 ° C. or more is inevitable in order to obtain magnetic characteristics. On the other hand, the present embodiment is characterized in that an insulating material for forming an insulating film is applied to the surface of the magnet powder, so that magnetic characteristics by liquid phase sintering like a conventional sintered magnet are used. Is relatively difficult to express. Therefore, it is preferable to use a magnet powder that already has magnetic properties. The heating temperature of such magnet powder is preferably 500 to 800 ° C. Heating at 800 ° C. or lower can effectively suppress the occurrence of microstructural changes such as grain growth, and can prevent deterioration of magnetic properties. On the other hand, if the heating is performed at 500 ° C. or higher, the deformation of the particles becomes sufficient, and a compact having a high density can be obtained. More preferably, it is 600-750 degreeC, More preferably, it is 620-720 degreeC. In addition, when densifying without applying pressure, the heating temperature is too low at 500 to 800 ° C., and heating at 1000 ° C. or higher may be necessary. Therefore, it is preferable to promote consolidation by applying pressure molding. In addition, as a pressure at the time of pressurization, from a viewpoint of promoting densification, Preferably it is 200-600 MPa, More preferably, it is 300-500 MPa.
得られた成形体は、歪み取りを目的として、５００〜８００℃の範囲で、再度加熱することにより、安定した磁気特性を得ることができる。 The obtained molded body can obtain stable magnetic characteristics by heating again in the range of 500 to 800 ° C. for the purpose of removing distortion.
以上のように、本実施形態は、絶縁皮膜形成用の絶縁物質（希土類酸化物など）により被覆された磁石粉末を、結着用の絶縁物質（希土類酸化物など）と共に高温で加熱加圧成形（焼結を含む）する。そして、成形された磁石においては、個々の磁石粉末が絶縁皮膜によって効果的に絶縁されると共に、絶縁された磁石粉末の粒子間に絶縁物質（絶縁皮膜形成用及び／または結着用）が介在することによって磁石粉末同士が結着した構造をとる。そのため、従来、絶縁材の混合や被覆のみでは避けることのできなかった磁石粉末間の絶縁不良部を、本実施形態によれば大幅に低減することができる。これにより、成形後の本実施形態に係る磁石成型体の電気抵抗が増し、かような永久磁石を搭載したモータの渦電流損失を減らすことにより、モータ効率の向上が可能になるという優れた効果がもたらされる。 As described above, in the present embodiment, magnet powder coated with an insulating material (such as a rare earth oxide) for forming an insulating film is heated and pressed at a high temperature together with a binding insulating material (such as a rare earth oxide). Including sintering). In the molded magnet, each magnet powder is effectively insulated by the insulating film, and an insulating substance (for insulating film formation and / or binding) is interposed between the particles of the insulated magnet powder. As a result, the magnet powder is bonded to each other. Therefore, according to the present embodiment, it is possible to greatly reduce the insulation failure portion between the magnet powders, which could not be avoided only by mixing and covering the insulating material. As a result, the electrical resistance of the molded magnet according to this embodiment after molding is increased, and the motor efficiency can be improved by reducing the eddy current loss of the motor equipped with such a permanent magnet. Is brought about.
さらに、例えば加熱温度が高くなる等の理由から製造条件が所望の範囲から外れると、絶縁被覆材の残留物に起因して不可避的に起こる、絶縁物質（希土類酸化物）と磁石粉末（希土類磁石粉末）との化学反応により、磁気特性が顕著に低下しうる。これに対し、本実施形態では、磁気特性の劣化が、バルク磁石を構成する磁石粉末の表面に限定され、個々の磁石粉末内部の磁気特性は維持される。したがって、厳しい条件下での高温加圧成形を経た後でも、高密度で、且つ良好な電気抵抗性や磁気特性を有するバルク磁石が得られる。 Furthermore, if the manufacturing conditions deviate from the desired range, for example, because the heating temperature becomes high, insulating materials (rare earth oxides) and magnet powder (rare earth magnets) inevitably occur due to the residual insulation coating material. Due to the chemical reaction with the powder, the magnetic properties can be significantly reduced. On the other hand, in this embodiment, the deterioration of the magnetic characteristics is limited to the surface of the magnet powder constituting the bulk magnet, and the magnetic characteristics inside the individual magnet powder are maintained. Therefore, a bulk magnet having a high density and good electrical resistance and magnetic properties can be obtained even after high-temperature pressure molding under severe conditions.
［第３実施形態］
本発明の第３実施形態に係るモータは、上記第１実施形態の磁石成形体及び上記第２実施形態の製造方法により得られる磁石成形体を用いてなる。参考までに図５に、本発明の磁石成形体が適用された集中巻の表面磁石型モータの１／４断面図を示す。図中、２１はｕ相巻線、２２はｕ相巻線、２３はｖ相巻線、２４はｖ相巻線、２５はｗ相巻線、２６はｗ相巻線、２７はアルミケース、２８はステータ、２９は磁石、３０はロータ鉄、３１は軸である。上記第１及び第２の実施形態による磁石成形体は、高い電気抵抗を有し、その上、保磁力などの磁石特性にも優れる。このため、上記第１及び第２の実施形態の磁石成形体を用いて製造されたモータを利用すれば、モータの連続出力を高めることが容易に可能であり、特に大出力のモータとして好適といえる。また、本実施形態の磁石成形体を用いたモータは、保磁力などの磁石特性が優れるために、製品の小型軽量化が図れる。
[Third Embodiment]
The motor according to the third embodiment of the present invention uses the magnet molded body obtained by the magnet molded body of the first embodiment and the manufacturing method of the second embodiment. For reference, FIG. 5 shows a quarter cross-sectional view of a concentrated surface magnet type motor to which the magnet molded body of the present invention is applied. In the figure, 21 is a u-phase winding, 22 is a u-phase winding, 23 is a v-phase winding, 24 is a v-phase winding, 25 is a w-phase winding, 26 is a w-phase winding, 27 is an aluminum case, 28 is a stator, 29 is a magnet, 30 is a rotor iron, and 31 is a shaft. The magnet compacts according to the first and second embodiments have high electrical resistance, and are excellent in magnet characteristics such as coercive force. For this reason, if the motor manufactured using the magnet molded body of the said 1st and 2nd embodiment is utilized, it will be possible to raise the continuous output of a motor easily, and it is especially suitable as a high output motor. I can say that. Moreover, since the motor using the magnet molded body of this embodiment has excellent magnet characteristics such as coercive force, the product can be reduced in size and weight.
［第４実施形態］
本発明の第４実施形態に係る電動駆動車両は、上記第３実施形態のモータを搭載してなる。上記第３実施形態の、磁石成形体を用いたモータは、例えば、自動車用部品に適用した場合には、車体の軽量化に伴う燃費の向上が可能である。さらに、特に電気自動車やハイブリッド電気自動車の駆動用モータとしても有効である。これまではスペースの確保が困難であった場所にも駆動用モータを搭載することが可能となり、電気自動車やハイブリッド電気自動車の汎用化に大きな役割を果たすと考えられる。
[Fourth Embodiment]
The electrically driven vehicle according to the fourth embodiment of the present invention is equipped with the motor of the third embodiment. When the motor using the magnet molded body of the third embodiment is applied to, for example, an automobile part, fuel efficiency can be improved along with the weight reduction of the vehicle body. Furthermore, it is particularly effective as a drive motor for electric vehicles and hybrid electric vehicles. Drive motors can be installed in places where it has been difficult to secure space so far, and it will play a major role in the generalization of electric vehicles and hybrid electric vehicles.
以下、本発明を実施例に基づいて具体的に説明するが、以下の実施例によって本発明の技術的範囲は何ら限定されるものではない。 EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, the technical scope of this invention is not limited at all by the following examples.
［実施例１］
希土類磁石として、ＨＤＤＲ法を用いて調製したＮｄ−Ｆｅ−Ｂ系異方性磁石粉末を用いた。具体的な調製の手順は以下の通りである。
[Example 1]
As the rare earth magnet, Nd—Fe—B based anisotropic magnet powder prepared by the HDDR method was used. The specific preparation procedure is as follows.
まず、「Ｎｄ：１２．６％、Ｃｏ：１７．４％、Ｂ：６．５％、Ｇａ：０．３％、Ａｌ：０．５％、Ｚｒ：０．１％、Ｆｅ：残部」の成分組成を有する鋳塊を準備し、この鋳塊を１１２０℃に２０時間保持して均質化した。さらに、均質化した鋳塊を水素雰囲気中で室温から５００℃まで昇温させて保持し、さらに８５０℃まで昇温させて保持した。 First, “Nd: 12.6%, Co: 17.4%, B: 6.5%, Ga: 0.3%, Al: 0.5%, Zr: 0.1%, Fe: balance” An ingot having a component composition was prepared, and the ingot was kept at 1120 ° C. for 20 hours for homogenization. Furthermore, the homogenized ingot was heated from room temperature to 500 ° C. and held in a hydrogen atmosphere, and further heated to 850 ° C. and held.
引き続いて８５０℃の真空中に保持した後、冷却して微細な強磁性相の再結晶組織を有する合金を得た。この合金をジョークラッシャー及びブラウンミルを用いて、Ａｒ雰囲気中で粉体化し、粒径（平均値）が２００μｍの希土類磁石粉末とした。さらに、篩いにて分級して目的の範囲の粒径を有する磁石粉末を得た。 Subsequently, the alloy was kept in a vacuum at 850 ° C. and then cooled to obtain an alloy having a recrystallized structure of a fine ferromagnetic phase. This alloy was pulverized in an Ar atmosphere using a jaw crusher and a brown mill to obtain a rare earth magnet powder having a particle size (average value) of 200 μm. Furthermore, classification was performed with a sieve to obtain a magnet powder having a particle size in the target range.
磁石粉末は、２５０μｍ超の粉末と、１５０μｍ超２５０μｍ以下の粉末と、７５μｍ超１５０μｍ以下の粉末と、７５μｍ以下の粉末とに分級した。その後、１５０μｍ超２５０μｍ以下の粉末８ｇと７５μｍ以下の粉末２ｇとを混合して、よく攪拌して被覆処理用の原料磁石粉末として用いた。 The magnet powder was classified into a powder of more than 250 μm, a powder of more than 150 μm and not more than 250 μm, a powder of more than 75 μm and not more than 150 μm, and a powder of not more than 75 μm. Thereafter, 8 g of a powder having a size of 150 μm or more and 250 μm or less and 2 g of a powder having a size of 75 μm or less were mixed and stirred well to be used as a raw material magnet powder for coating treatment.
上記で得られた被覆処理後の磁石粉末のＳＥＭ写真を図６Ａに示す。図６Ｂは、被覆処理前の磁石粉末のＳＥＭ写真（倍率は図６Ａと同じ）である。図６Ｃ、図６Ｄは図６Ｂの断面のＳＥＭ写真である。 An SEM photograph of the magnet powder after the coating treatment obtained above is shown in FIG. 6A. FIG. 6B is an SEM photograph (magnification is the same as FIG. 6A) of the magnet powder before the coating treatment. 6C and 6D are SEM photographs of the cross section of FIG. 6B.
希土類磁石粉末の表面への絶縁皮膜の形成には、希土類アルコキシドであるジスプロシウムトリイソプロポキシド（（株）高純度化学研究所製）を塗布し、ジスプロシウムトリイソプロポキシドの加熱処理による重縮合により、希土類酸化物を表面に固着させる手法を採用した。絶縁皮膜の形成から磁石の成形に至るまでの詳細な手順は、以下の通りである。 The insulation film is formed on the surface of the rare earth magnet powder by applying dysprosium triisopropoxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.), which is a rare earth alkoxide, and by polycondensation by heat treatment of dysprosium triisopropoxide. The technique of fixing the rare earth oxide to the surface was adopted. The detailed procedure from the formation of the insulating film to the molding of the magnet is as follows.
（１）露点が−８０℃以下のＡｒガスを満たしたグローブボックス内で、希土類アルコキシドであるジスプロシウムトリイソプロポキシド２０ｇに、有機溶媒として脱水ヘキサンを加えて溶解し、全量が１００ｍｌのジスプロシウム表面処理液を調製した。ＩＣＰにて、溶液残渣中のＤｙ濃度を分析した結果、５．３ｍｇ/ｍｌであった。 (1) In a glove box filled with Ar gas having a dew point of −80 ° C. or less, 20 g of dysprosium triisopropoxide, which is a rare earth alkoxide, is dissolved by adding dehydrated hexane as an organic solvent, and the total amount is 100 ml of dysprosium surface treatment A liquid was prepared. As a result of analyzing the Dy concentration in the solution residue by ICP, it was 5.3 mg / ml.
（２）Ａｒ雰囲気としたグローブボックス内で、前記ジスプロシウム表面処理液３０ｍｌを、上記で得た混合粉末１０ｇに添加し、攪拌したのち、溶媒を除去し、混合粉末の表面を、希土類アルコキシド（ジスプロシウムトリイソプロポキシド）で被覆した。 (2) In a glove box having an Ar atmosphere, 30 ml of the dysprosium surface treatment solution is added to 10 g of the mixed powder obtained above, stirred, the solvent is removed, and the surface of the mixed powder is treated with a rare earth alkoxide (dysprosium). Triisopropoxide).
（３）上記の操作により得られた皮膜を有する磁石粉末を、真空中で３５０℃にて３０分間熱処理した。引き続き、６００℃で６０分間熱処理を実施して、錯体を熱分解し、絶縁皮膜を形成することにより、被覆粉末を得た。 (3) The magnet powder having the film obtained by the above operation was heat-treated at 350 ° C. for 30 minutes in a vacuum. Subsequently, a heat treatment was performed at 600 ° C. for 60 minutes to thermally decompose the complex and form an insulating film, thereby obtaining a coated powder.
被覆後の磁石粉末の断面をＳＥＭ観察した結果、希土類酸化物から成る絶縁被覆の膜厚は、厚いところで約５μｍであった（図示せず）。また、薄いところでは、オージェ電子分光（ＡＥＳ）解析によって表面からの酸素の浸透深さを測定した結果、約１００ｎｍであった（図示せず）。なお、前記断面は、耳かき一杯分の粉を埋め込み研磨して、数十個の粉の断面を見たものである。 As a result of SEM observation of the cross section of the magnet powder after coating, the thickness of the insulating coating made of rare earth oxide was about 5 μm (not shown). Moreover, in the thin place, as a result of measuring the penetration depth of oxygen from the surface by Auger electron spectroscopy (AES) analysis, it was about 100 nm (not shown). The cross section is a cross-section of several tens of powders obtained by embedding and polishing powder for one earpick.
得られた希土類酸化物で被覆された軟磁性合金粉末に、希土類酸化物としてＤｙ２Ｏ３を体積比で２．５％となるように混合し、十分に攪拌し、４ｇの混合物を調製した。上記の希土類酸化物（Ｄｙ２Ｏ３）の平均粒径は、走査型電子顕微鏡（ＳＥＭ）観察の結果０．５〜５μｍであった。なお、前記「平均粒径」とは、ＳＥＭにより得られたイメージより、無作為に選択した２０個の磁石粉末の長軸及び短軸を測定し、それらの平均を算出して得られる値を意味する。 To the obtained soft magnetic alloy powder coated with the rare earth oxide, Dy 2 O 3 was mixed as a rare earth oxide so that the volume ratio was 2.5%, and stirred sufficiently to prepare 4 g of a mixture. . The average particle diameter of the rare earth oxide (Dy 2 O 3 ) was 0.5 to 5 μm as a result of observation with a scanning electron microscope (SEM). The “average particle size” is a value obtained by measuring the major and minor axes of 20 randomly selected magnet powders from the image obtained by SEM and calculating the average of them. means.
なお、上記希土類酸化物の添加量については、希土類磁石粉末と希土類酸化物粉末のバルク体における真密度の値を用いて、計算によって求めた。また、上記希土類酸化物は、（株）高純度化学研究所製のＤｙ２Ｏ３試薬を用いた。 In addition, about the addition amount of the said rare earth oxide, it calculated | required by calculation using the value of the true density in the bulk body of rare earth magnet powder and rare earth oxide powder. As the rare earth oxide, Dy 2 O 3 reagent manufactured by Kojundo Chemical Laboratory Co., Ltd. was used.
上記混合粉末を１０ｍｍ×１０ｍｍのプレス面を有する金型に充填し、室温で磁場配向させながら仮成形した。この時の配向磁場は１．６ＭＡ／ｍ、成形圧力は２０ＭＰａとした。 The mixed powder was filled in a mold having a 10 mm × 10 mm press surface, and temporarily molded while being magnetically oriented at room temperature. The orientation magnetic field at this time was 1.6 MA / m, and the molding pressure was 20 MPa.
そして、仮成形された上記混合体を真空中での加圧焼成によって成形し、バルク成形体の希土類磁石を得た。この成形にはホットプレスを用い、昇温中も一定の成形圧力４９０ＭＰａを保持すると共に、成形温度６００℃で１分間保持し、冷却することにより、１０ｍｍ×１０ｍｍ×約５ｍｍの寸法を有する希土類磁石に加工した。なお、このとき、冷却中も室温まで真空を保持した。また、得られた磁石圧密体には、６００℃で０．５時間、歪取り焼鈍を施した。 And the said preformed mixture was shape | molded by the pressurization baking in a vacuum, and the rare earth magnet of the bulk molded object was obtained. A rare earth magnet having a size of 10 mm × 10 mm × about 5 mm is obtained by using a hot press for this molding, holding a constant molding pressure of 490 MPa even during temperature rise, holding at a molding temperature of 600 ° C. for 1 minute, and cooling. It was processed into. At this time, the vacuum was kept to room temperature even during cooling. In addition, the obtained magnet compact was subjected to strain relief annealing at 600 ° C. for 0.5 hour.
このようにして得られた希土類磁石について、その密度（単位：ｇ／ｃｍ３）、磁気特性（保磁力（ｉＨｃ）（単位：ＫＡ/ｍ）、最大エネルギー積ＢＨｍａｘ（単位：ｋＪ／ｍ３））、及び電気比抵抗（単位：μΩｍ）を測定した。このとき、上記密度は得られた磁石の寸法及び密度から算出する一方、保磁力及び最大エネルギー積の磁石特性については、東英工業（株）製パルス励磁型着磁器ＭＰＭ−１５を用いた。そして、着磁磁界１０Ｔにて予め着磁した試験片を準備し、東英工業（株）製ＢＨ測定器ＴＲＦ−５ＡＨ−２５Ａｕｔｏを用いてＢ-Ｈ曲線を測定することにより求めた。また、電気抵抗率（電気比抵抗）については、エヌピイエス（株）製抵抗率プローブを使用した４探針法によって測定した。このとき、プローブの針材料をタングステンカーバイド、針先端半径を４０μｍ、針間隔を１ｍｍ、４本の針の総荷重は４００ｇとした。 The rare earth magnet thus obtained has its density (unit: g / cm 3 ), magnetic properties (coercivity (iHc) (unit: KA / m), maximum energy product BH max (unit: kJ / m 3). )) And electrical resistivity (unit: μΩm). At this time, the density was calculated from the size and density of the obtained magnet, while the magnet characteristics of the coercive force and the maximum energy product were a pulse excitation type magnetizer MPM-15 manufactured by Toei Kogyo Co., Ltd. A test piece magnetized in advance with a magnetizing magnetic field of 10T was prepared, and the BH curve was measured using a BH measuring instrument TRF-5AH-25Auto manufactured by Toei Kogyo Co., Ltd. The electrical resistivity (electrical resistivity) was measured by a four-probe method using a resistivity probe manufactured by NP Corporation. At this time, the needle material of the probe was tungsten carbide, the needle tip radius was 40 μm, the needle interval was 1 mm, and the total load of the four needles was 400 g.
当該実施例１において得られた希土類磁石の磁石密度は７．４ｇ／ｃｍ３、保磁力は８４８ＫＡ／ｍ、最大エネルギー積は１３９ＫＪ／ｍ３、比抵抗は２８０μΩcｍであった。以上の条件及び結果を表１に示す。 The magnet density of the rare earth magnet obtained in Example 1 was 7.4 g / cm 3 , the coercive force was 848 KA / m, the maximum energy product was 139 KJ / m 3 , and the specific resistance was 280 μΩcm. The above conditions and results are shown in Table 1.
［実施例２〜１０、比較例１〜４］
混合した原料磁石粉末粒径の混合比を表１に示した条件とした以外は、実施例１と同様にして実験を行った。
[Examples 2 to 10, Comparative Examples 1 to 4]
An experiment was conducted in the same manner as in Example 1 except that the mixing ratio of the mixed raw material magnet powder particle diameters was changed to the conditions shown in Table 1.
［比較例５］
分級を行わず、被覆処理も行わなかった点を除いて、実施例１と同様にして実験を行った。
[Comparative Example 5]
An experiment was conducted in the same manner as in Example 1 except that no classification was performed and no coating treatment was performed.
以上の条件及び結果を表１にまとめて示す。さらに、表１における結果をプロットしたグラフを図７に示す。 The above conditions and results are summarized in Table 1. Furthermore, the graph which plotted the result in Table 1 is shown in FIG.
表１より、磁石粒子について、断面観察による粒径１５０μｍ超の粒子断面率が５０％以上の条件を満たす磁石成形体の場合、かかる条件を満たさない磁石成形体と比較して、電気比抵抗及び磁気特性（保磁力）が共に有意に高い値を示すことを確認した。 From Table 1, in the case of a magnet molded body that satisfies the condition that the particle cross-section ratio of the particle diameter of more than 150 μm by cross-sectional observation satisfies 50% or more from the magnetic particles, the electrical resistivity and It was confirmed that both the magnetic properties (coercivity) showed significantly high values.
１ 磁石成形前駆体、
２ 磁石粉末、
３ 絶縁皮膜、
２１ ｕ相巻線、
２２ ｕ相巻線、
２３ ｖ相巻線、
２４ ｖ相巻線、
２５ ｗ相巻線、
２６ ｗ相巻線、
２７ アルミケース、
２８ ステータ、
２９ 磁石、
３０ ロータ鉄、
３１ 軸。
1 magnet molding precursor,
2 magnet powder,
3 Insulating film,
21 u-phase winding,
22 u-phase winding,
23 v-phase winding,
24 v phase winding,
25 w phase winding,
26 w-phase winding,
27 Aluminum case,
28 stator,
29 magnets,
30 Rotor iron,
31 axes.
Claims (8)
前記絶縁皮膜で被覆された前記磁石粉末の粒径が１５０μｍ超の粒子を断面の面積率として５０％以上有する、磁石成形体。 A magnet molded body including magnet powder and an insulating film covering the magnet powder,
A magnet molded body having particles having a particle size of more than 150 μm coated with the insulating film and having a cross-sectional area ratio of 50% or more.
磁石粉末を絶縁皮膜で被覆して磁石成形前駆体を得る段階と、
前記磁石成形前駆体を加熱加圧成形する段階とを含む、磁石成形体の製造方法。 It is a manufacturing method of the magnet fabrication object according to any one of claims 1 to 5,
Coating a magnetic powder with an insulating film to obtain a magnet molding precursor;
And a step of heat-pressing the magnet molding precursor.
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| CN106769162A (en) * | 2017-02-20 | 2017-05-31 | 广西大学 | A kind of transmission electron microscope magnetic sample preprocessor |
| JP2019186368A (en) * | 2018-04-09 | 2019-10-24 | トヨタ自動車株式会社 | Manufacturing method of rare-earth magnet and manufacturing installation for use therein |
| JP2021158205A (en) * | 2020-03-26 | 2021-10-07 | Tdk株式会社 | R-t-b based permanent magnet |
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