JP6513623B2 - Method of manufacturing isotropic bulk magnet - Google Patents
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Description
本発明は、等方性バルク磁石および等方性バルク磁石の製造方法に関する。 The present invention relates to an isotropic bulk magnet and a method of manufacturing an isotropic bulk magnet.
機器の小型化、高性能化に伴い、機器中のモータに使われる磁石として、高磁気特性を有する希土類永久磁石の使用が増えている。また、近年、モータは車載用途の需要が増えてきており、耐熱性や耐環境性が求められている。モータ用磁石として、磁石粉末と樹脂とを混合して成形した磁石(いわゆる、ボンド磁石)がある。しかしながら、ボンド磁石は、成形の自由度がある一方、バインダに有機材料である樹脂を使用しているため、エンジンルームなどの高温となる環境下での使用は難しい。 With the miniaturization and high performance of devices, the use of rare earth permanent magnets having high magnetic properties is increasing as magnets used for motors in the devices. In recent years, the demand for motors for vehicles has been increasing, and heat resistance and environmental resistance are required. As a motor magnet, there is a magnet (so-called bonded magnet) formed by mixing magnet powder and resin. However, while the bond magnet has a degree of freedom in molding, it is difficult to use it in a high temperature environment such as an engine room since a resin which is an organic material is used as a binder.
これに対して、特許文献１では、合金組成Ｎｄ１４．０Ｃｏ７．５Ｂ６．０Ｆｅ７２．５の合金を溶融して合金薄片を作製し、この合金薄片について、バインダを用いずに放電プラズマ焼結（Spark Plasma Sintering（ＳＰＳ）（なお、本明細書において「放電プラズマ焼結」を「ＳＰＳ」ともいう。））させて希土類鉄系永久磁石を製造している。 On the other hand, in patent document 1, an alloy of the alloy composition Nd 14.0 Co 7.5 B 6.0 Fe 72.5 is melted to prepare an alloy flake, and this alloy flake is used without using a binder Discharge plasma sintering (Spark Plasma Sintering (SPS) (herein, "discharge plasma sintering" is also referred to as "SPS" in this specification)) is carried out to produce a rare earth iron-based permanent magnet.
また、特許文献２では、希土類−鉄系合金を主体とする急冷磁石粉末と、無機バインダとから得られた粉末磁石混練物に対して、成形型中で直接圧縮通電してフル密度複合磁石を製造している。なお、特許文献２には、無機バインダは磁石粉末の結晶化温度あるいはそれよりやや低い温度で熱軟化することが望ましいと記載されている。また、特許文献２では、ＳＰＳにおける焼結温度を低くできる。 Further, in Patent Document 2, a full density composite magnet is obtained by direct compression conduction in a mold with respect to a powder magnet kneaded material obtained from a quenched magnet powder mainly composed of a rare earth-iron alloy and an inorganic binder. It manufactures. Patent Document 2 describes that it is desirable that the inorganic binder be thermally softened at or slightly lower than the crystallization temperature of the magnet powder. Moreover, in patent document 2, the sintering temperature in SPS can be made low.
しかしながら、特許文献１では、焼結を容易にするために希土類量の多い磁粉のみを使用しており、磁粉のコストが高くなってしまう。また、残留磁化（残留磁束密度）も希土類の増加と共に低下する傾向がある。また、特許文献２で得られる希土類鉄系永久磁石は、高い電気抵抗を有する磁石を得る目的で無機バインダが混合されているため、残留磁束密度（Ｂｒ）が低い。 However, in patent document 1, in order to make sintering easy, only the magnetic powder with many amounts of rare earths is used, and the cost of magnetic powder will become high. In addition, the residual magnetization (residual magnetic flux density) also tends to decrease with the increase of the rare earth. Further, the rare earth iron-based permanent magnet obtained in Patent Document 2 has a low residual magnetic flux density (Br) because an inorganic binder is mixed for the purpose of obtaining a magnet having a high electrical resistance.
本発明は、上記に鑑みてなされたものであって、本発明の目的は、希土類元素の使用量を低減し、残留磁束密度（Ｂｒ）および実用的な保磁力（Ｈｃ）を確保できる等方性バルク磁石を提供することを目的とする。 The present invention has been made in view of the above, and an object of the present invention is to reduce the amount of use of rare earth elements, and to ensure that residual magnetic flux density (Br) and practical coercive force (Hc) can be secured. Purpose is to provide a magnetic bulk magnet.
上述した課題を解決し、目的を達成するために、本発明の一態様に係る等方性バルク磁石は、希土類元素が１２ａｔ％以下の量で含まれるＮｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）と、希土類元素が１２ａｔ％よりも多い量で含まれるＮｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）とを含む。 In order to solve the problems described above and achieve the object, an isotropic bulk magnet according to an aspect of the present invention is a region of an Nd—Fe—B based magnet that contains rare earth elements in an amount of 12 at% or less And the region (B) of the Nd—Fe—B based magnet containing the rare earth element in an amount of more than 12 at%.
本発明の一態様によれば、高価な希土類元素の使用量を低減でき、残留磁束密度（Ｂｒ）および保磁力（Ｈｃ）を確保できる。 According to one aspect of the present invention, the amount of expensive rare earth element used can be reduced, and the residual magnetic flux density (Br) and the coercive force (Hc) can be secured.
以下、実施の形態について、詳細に説明する。なお、以下の実施の形態により何ら限定されるものではない。 Hereinafter, the embodiment will be described in detail. In addition, it is not limited at all by the following embodiment.
＜等方性バルク磁石の製造方法＞
本実施の形態に係る等方性バルク磁石の製造方法は、希土類元素が１２ａｔ％以下の量で含まれるＮｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）と、希土類元素が１２ａｔ％よりも多い量で含まれるＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）とを混合して混合粉末を得る混合工程と、上記混合工程で得られた混合粉末を加圧しながら加熱して等方性バルク磁石を得る加熱工程とを含む。
<Method of manufacturing isotropic bulk magnet>
In the method for producing an isotropic bulk magnet according to the present embodiment, an Nd-Fe-B based magnet powder (A) containing a rare earth element in an amount of 12 at% or less and an amount of a rare earth element in an amount of more than 12 at% A mixing step of mixing with the contained Nd-Fe-B magnet powder (B) to obtain a mixed powder, and heating while obtaining pressure of the mixed powder obtained in the above mixing step to obtain an isotropic bulk magnet And a process.
希土類元素の含有量が少なく、等方性の磁粉として通常大きい残留磁束密度（Ｂｒ）を有するＮｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）は、単独では緻密化しにくい。一方、希土類元素の含有量が多く、等方性の磁粉として通常大きい保磁力（Ｈｃ）を有するＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）は、緻密化が容易である。そこで、本実施の形態のように、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）とともにＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を用いると、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）がバインダとして働き、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）が緻密化した等方性バルク磁石が得られる。より詳細には、たとえばＳＰＳ等による焼結は液相焼結であるため、低い温度で液相となる希土類元素リッチ相、たとえばＮｄリッチ相（主相のＮｄ2Ｆｅ14Ｂ6よりもＮｄ量の多い組成の相など）が必要である。希土類元素の含有量が少ないＮｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）は、希土類元素リッチ相（Ｎｄリッチ相）を少量含んでいるにすぎないが、希土類元素の含有量が多いＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）は、希土類元素リッチ相（Ｎｄリッチ相）を多く含んでいる。これにより、焼結の際には、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の希土類元素リッチ相（Ｎｄリッチ相）が液相となって緻密化が進行する。 An Nd--Fe--B based magnet powder (A) having a small residual rare earth element content and a large residual magnetic flux density (Br) as isotropic magnetic powder is difficult to densify alone. On the other hand, Nd--Fe--B based magnet powder (B) having a large content of rare earth elements and generally large coercive force (Hc) as isotropic magnetic powder is easy to be densified. Therefore, if Nd-Fe-B magnet powder (B) is used together with Nd-Fe-B magnet powder (A) as in the present embodiment, the Nd-Fe-B magnet powder (B) is a binder. Thus, it is possible to obtain an isotropic bulk magnet in which the Nd-Fe-B based magnet powder (A) is densified. More specifically, for example, since sintering by SPS or the like is liquid phase sintering, a rare earth element rich phase which becomes a liquid phase at a low temperature, for example, an Nd rich phase (Nd content rather than the main phase Nd 2 Fe 14 B 6 And so on) is required. An Nd-Fe-B based magnet powder (A) containing a small amount of rare earth elements only contains a small amount of a rare earth element rich phase (Nd rich phase), but Nd-Fe- containing a large amount of rare earth elements. The B-based magnet powder (B) contains a large amount of a rare earth element rich phase (Nd rich phase). Thereby, at the time of sintering, the rare earth element rich phase (Nd rich phase) of the Nd--Fe--B based magnet powder (B) becomes a liquid phase and the densification proceeds.
また、本実施の形態によれば、希土類元素の含有量が多い原料を用いる特許文献１の製造方法よりも、希土類元素の使用量を低減できる。希土類元素の価格が高騰しているため、本実施の形態はコストの面からもメリットがある。また、本実施の形態ではバインダとして磁石粉末を使用しているため、無機バインダを使用している特許文献２の製造方法よりも、残留磁束密度（Ｂｒ）の高い等方性バルク磁石が得られる。 Moreover, according to the present embodiment, the amount of use of the rare earth element can be reduced as compared with the manufacturing method of Patent Document 1 using the raw material having a large content of the rare earth element. Because the price of the rare earth element is rising, the present embodiment is also advantageous in terms of cost. In addition, since magnet powder is used as a binder in the present embodiment, an isotropic bulk magnet having a high residual magnetic flux density (Br) can be obtained as compared with the manufacturing method of Patent Document 2 using an inorganic binder. .
（混合工程）
混合工程では、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）と、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）とを混合して混合粉末を得る。
(Mixing process)
In the mixing step, the Nd-Fe-B based magnet powder (A) and the Nd-Fe-B based magnet powder (B) are mixed to obtain a mixed powder.
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）を構成する等方性のＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、希土類元素は１２ａｔ％以下の量で含まれ、８ａｔ％以上１１ａｔ％以下の量で含まれることが好ましい。ここで、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石に含まれる希土類元素は、Ｎｄのみであってもよく、Ｎｄおよび後述する元素（ｅ１）であってもよい。したがって、希土類元素がＮｄのみのときの希土類元素の量は、Ｎｄのみの量であり、希土類元素がＮｄおよび後述する元素（ｅ１）のときの希土類元素の量は、Ｎｄおよび後述する元素（ｅ１）の合計量である。Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）は、１種単独で用いても、２種以上を混合して用いてもよい。この範囲にあると、Ｎｄ−Ｆｅ−Ｂ系磁石は通常大きい残留磁束密度（Ｂｒ）を有し、本実施の形態において希土類元素の使用量を低減できる。 In the isotropic Nd-Fe-B magnet (100 at%) constituting the Nd-Fe-B magnet powder (A), the rare earth element is contained in an amount of 12 at% or less, and 8 at% or more and 11 at% or less It is preferred to be included in an amount. Here, the rare earth element contained in the Nd-Fe-B magnet constituting the Nd-Fe-B magnet powder (A) may be only Nd, and is Nd and an element (e1) described later It is also good. Therefore, when the rare earth element is Nd only, the amount of the rare earth element is only Nd, and when the rare earth element is Nd and the element (e1) to be described later, the amount of the rare earth element is Nd and an element to be described (e1) Total amount of The Nd-Fe-B based magnet powder (A) may be used singly or in combination of two or more. Within this range, the Nd-Fe-B based magnet usually has a large residual magnetic flux density (Br), and the amount of the rare earth element used can be reduced in the present embodiment.
このようなＮｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）としては、たとえばナノコンポジットタイプの磁石粉末（具体的には、ＭＱＰ−１５−７（商品名）、マグネクエンチ社製）が好適に用いられる。ナノコンポジットタイプの磁石は、通常α−Ｆｅ相／Ｎｄ2Ｆｅ14Ｂ相、Ｆｅ3Ｂ相／Ｎｄ2Ｆｅ14Ｂ相のようにソフト相およびハード相を含み、全体の希土類量が少ないことから希土類元素リッチ相（Ｎｄリッチ相）の量が少ない。 As such Nd-Fe-B based magnet powder (A), for example, nanocomposite type magnet powder (specifically, MQP-15-7 (trade name), manufactured by Magnequench Co., Ltd.) is suitably used. . The magnet of the nanocomposite type usually contains soft phase and hard phase like α-Fe phase / Nd 2 Fe 14 B phase, Fe 3 B phase / Nd 2 Fe 14 B phase, and the total amount of rare earth is small. The amount of rare earth element rich phase (Nd rich phase) is small.
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）（具体的には、上記粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）は、Ｎｄ、ＦｅおよびＢの他に、希土類元素として、Ｓｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、ＹｂおよびＬｕからなる群から選択された少なくとも１種の元素（ｅ１）をさらに含んでいてもよい。 Nd-Fe-B based magnet powder (A) (specifically, the Nd-Fe-B based magnet constituting the above-mentioned powder (A)) contains Sc, as a rare earth element, in addition to Nd, Fe and B. And at least one element (e1) selected from the group consisting of Y, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Good.
また、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）（具体的には、上記粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）は、Ｎｄ、ＦｅおよびＢの他に、Ｔｉ、Ｃｏ、Ｚｒ、Ｎｂ、Ｍｏ、Ｈｆ、ＴａおよびＷからなる群から選択された少なくとも１種の元素（ｅ２）をさらに含んでいてもよい。 In addition to Nd, Fe and B, Nd-Fe-B based magnet powder (A) (specifically, Nd-Fe-B based magnet constituting the above-mentioned powder (A)), Ti, Co, It may further contain at least one element (e2) selected from the group consisting of Zr, Nb, Mo, Hf, Ta and W.
なお、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）（具体的には、上記粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）は、Ｓｉ、Ａｌ等の不可避の不純物元素を含む場合がある。 The Nd-Fe-B magnet powder (A) (specifically, the Nd-Fe-B magnet constituting the powder (A)) may contain unavoidable impurity elements such as Si and Al. is there.
また、上記粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、Ｂは３ａｔ％以上１０ａｔ％以下の量で含まれることが好ましい。 Moreover, it is preferable that B is contained in the quantity of 3 at% or more and 10 at% or less in the Nd-Fe-B type | system | group magnet (100 at%) which comprises the said powder (A).
元素（ｅ１）を含む場合、上記粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、元素（ｅ１）は、合計で０ａｔ％を超え４ａｔ％以下の量であり、かつＮｄよりも少ない量で含まれることが好ましい。また、元素（ｅ２）および／または不可避の不純物元素を含む場合、上記粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、元素（ｅ２）および／または不可避の不純物元素は、合計で０．１ａｔ％以上１０ａｔ％以下の量で含まれることが好ましい。 When the element (e1) is contained, in the Nd-Fe-B based magnet (100 at%) constituting the powder (A), the element (e1) is an amount of more than 0 at% and 4 at% or less in total Preferably, it is included in an amount smaller than Nd. When the element (e2) and / or the inevitable impurity element is contained, the element (e2) and / or the unavoidable impurity element in the Nd-Fe-B based magnet (100 at%) constituting the powder (A) is Preferably, the total amount is 0.1 at% or more and 10 at% or less.
ここで、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）（具体的には、上記粉末（Ａ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）において、上述したいずれの場合も、残部（ａｔ％）はＦｅである。 Here, in the Nd-Fe-B based magnet powder (A) (specifically, the Nd-Fe-B based magnet constituting the above-mentioned powder (A)), the remaining portion (at%) in any case described above Is Fe.
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）の粒子の粒径は、緻密化促進の観点から、７５μｍ以上３５５μｍ以下であることが好ましい。粒径が７５μｍ未満となると、ＳＰＳによる焼結性が悪くなり、緻密化したときの磁気特性が低下してしまうことがある。上記平均粒径は、日本工業規格ＪＩＳ Ｚ８８１５のふるい分け法に準拠して測定される。また、２．５μｍ以下の細かい平均粒径の測定は、レーザー回折式粒度測定分布法により測定することができる。 The particle diameter of the particles of the Nd-Fe-B based magnet powder (A) is preferably 75 μm or more and 355 μm or less from the viewpoint of promoting densification. When the particle size is less than 75 μm, the sinterability by SPS may be deteriorated, and the magnetic properties when densified may be deteriorated. The average particle size is measured in accordance with the sieving method of Japanese Industrial Standard JIS Z8815. The fine average particle diameter of 2.5 μm or less can be measured by a laser diffraction particle size distribution method.
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を構成する等方性のＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、希土類元素は１２ａｔ％超える量で含まれ、１３ａｔ％以上２１ａｔ％以下の量で含まれることが好ましく、１３．５ａｔ％以上１７ａｔ％以下の量で含まれることがより好ましい。ここで、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石に含まれる希土類元素は、Ｎｄのみであってもよく、Ｎｄおよび後述する元素（ｅ１）であってもよい。したがって、希土類元素がＮｄのみのときの希土類元素の量は、Ｎｄのみの量であり、希土類元素がＮｄおよび後述する元素（ｅ１）のときの希土類元素の量は、Ｎｄおよび後述する元素（ｅ１）の合計量である。Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）は、１種単独で用いても、２種以上を混合して用いてもよい。この範囲にあると、Ｎｄ−Ｆｅ−Ｂ系磁石は通常大きい保磁力（Ｈｃ）を有し、本実施の形態において緻密化を促進できる。 In the isotropic Nd-Fe-B magnet (100 at%) that constitutes the Nd-Fe-B magnet powder (B), the rare earth element is contained in an amount of more than 12 at%, and at least 13 at% but not more than 21 at% Is preferably contained, and more preferably contained in an amount of 13.5 at% or more and 17 at% or less. Here, the rare earth element contained in the Nd-Fe-B magnet constituting the Nd-Fe-B magnet powder (B) may be only Nd, and is Nd and an element (e1) described later It is also good. Therefore, when the rare earth element is Nd only, the amount of the rare earth element is only Nd, and when the rare earth element is Nd and the element (e1) to be described later, the amount of the rare earth element is Nd and an element to be described (e1) Total amount of The Nd-Fe-B based magnet powder (B) may be used alone or in combination of two or more. Within this range, the Nd-Fe-B based magnet usually has a large coercive force (Hc), and can promote densification in the present embodiment.
このようなＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）としては、具体的には、ＭＱＰ−Ａ（商品名）（マグネクエンチ社製）、ＭＱＰ−Ｃ（商品名）（マグネクエンチ社製）が好適に用いられる。この磁石は、通常主相としてＮｄ2Ｆｅ14Ｂ相を含み、全体の希土類量が多いため希土類元素リッチ相（Ｎｄリッチ相）の量が多い。 As such Nd-Fe-B magnet powder (B), specifically, MQP-A (trade name) (manufactured by Magnequench Co., Ltd.) and MQP-C (trade name) (manufactured by Magnequench Co., Ltd.) It is preferably used. This magnet usually contains the Nd 2 Fe 14 B phase as the main phase, and the amount of the rare earth element rich phase (Nd rich phase) is large because the total amount of the rare earth elements is large.
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）（具体的には、上記粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）は、Ｎｄ、ＦｅおよびＢの他に、希土類元素として、Ｓｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、ＹｂおよびＬｕからなる群から選択された少なくとも１種の元素（ｅ１）をさらに含んでいてもよい。 The Nd-Fe-B based magnet powder (B) (specifically, the Nd-Fe-B based magnet constituting the above powder (B)) contains Sc, as a rare earth element, in addition to Nd, Fe and B. And at least one element (e1) selected from the group consisting of Y, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Good.
また、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）（具体的には、上記粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）は、Ｎｄ、ＦｅおよびＢの他に、Ｔｉ、Ｃｏ、Ｚｒ、Ｎｂ、Ｍｏ、Ｈｆ、ＴａおよびＷからなる群から選択された少なくとも１種の元素（ｅ２）をさらに含んでいてもよい。 In addition to Nd, Fe and B, Nd-Fe-B based magnet powder (B) (specifically, the Nd-Fe-B based magnet constituting the above-mentioned powder (B)), Ti, Co, It may further contain at least one element (e2) selected from the group consisting of Zr, Nb, Mo, Hf, Ta and W.
なお、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）（具体的には、上記粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）は、Ｓｉ、Ａｌ等の不可避の不純物元素を含む場合がある。 The Nd-Fe-B magnet powder (B) (specifically, the Nd-Fe-B magnet constituting the powder (B)) may contain unavoidable impurity elements such as Si and Al. is there.
また、上記粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、Ｂは３ａｔ％以上１０ａｔ％以下の量で含まれることが好ましい。 Moreover, it is preferable that B is contained in the quantity of 3 at% or more and 10 at% or less in the Nd-Fe-B type | system | group magnet (100 at%) which comprises the said powder (B).
元素（ｅ１）を含む場合、上記粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、元素（ｅ１）は、合計で０ａｔ％を超え７ａｔ％以下の量であり、かつＮｄよりも少ない量で含まれることが好ましい。また、元素（ｅ２）および／または不可避の不純物元素を含む場合、上記粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石（１００ａｔ％）において、元素（ｅ２）および／または不可避の不純物元素は、合計で０．１ａｔ％以上１０ａｔ％以下の量で含まれることが好ましい。 When the element (e1) is contained, in the Nd-Fe-B based magnet (100 at%) constituting the powder (B), the element (e1) is an amount of more than 0 at% and at most 7 at%, and Preferably, it is included in an amount smaller than Nd. When the element (e2) and / or the unavoidable impurity element is contained, the element (e2) and / or the unavoidable impurity element in the Nd-Fe-B based magnet (100 at%) constituting the powder (B) is Preferably, the total amount is 0.1 at% or more and 10 at% or less.
ここで、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）（具体的には、上記粉末（Ｂ）を構成するＮｄ−Ｆｅ−Ｂ系磁石）において、上述したいずれの場合も、残部（ａｔ％）はＦｅである。 Here, in the Nd-Fe-B based magnet powder (B) (specifically, the Nd-Fe-B based magnet constituting the powder (B)), the remaining part (at%) in any case described above Is Fe.
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の粒子の粒径は、緻密化促進の観点から、７５μｍ以上３５５μｍ以下であることが好ましい。粒径が７５μｍ未満となると、ＳＰＳによる焼結性が悪くなり、緻密化したときの磁気特性が低下してしまうことがある。上記平均粒径の測定については、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）の場合と同様である。 The particle diameter of the particles of the Nd-Fe-B based magnet powder (B) is preferably 75 μm or more and 355 μm or less from the viewpoint of promoting densification. When the particle size is less than 75 μm, the sinterability by SPS may be deteriorated, and the magnetic properties when densified may be deteriorated. About the measurement of the said average particle diameter, it is the same as that of the case of Nd-Fe-B type | system | group magnet powder (A).
混合工程において、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）およびＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の合計１００ｗｔ％に対して、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）を、好ましくは０ｗｔ％を超え７０ｗｔ％以下の量で、より好ましくは２０ｗｔ％以上５０ｗｔ％以下の量で、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を、好ましくは３０ｗｔ％以上１００ｗｔ％未満の量で、より好ましくは５０ｗｔ％以上８０ｗｔ％以下の量で混合することが望ましい。混合量が上記範囲にあると、緻密化を促進できると同時に希土類元素の使用量が減らせる。また、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）およびＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の合計１００ｗｔ％に対して、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）を、さらに好ましくは２０ｗｔ％以上３０ｗｔ％以下の量で、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を、さらに好ましくは７０ｗｔ％以上８０ｗｔ％以下の量で混合することが望ましい。混合量が上記範囲にあると、残留磁束密度（Ｂｒ）および実用的な保磁力（Ｈｃ）を有した等方性バルク磁石が得られる。 In the mixing step, the Nd-Fe-B based magnet powder (A) is preferably added to the total 100 wt% of the Nd-Fe-B based magnet powder (A) and the Nd-Fe-B based magnet powder (B) Nd-Fe-B magnet powder (B) in an amount of more than 0 wt% and 70 wt% or less, more preferably 20 wt% or more and 50 wt% or less, preferably in an amount of 30 wt% or more and less than 100 wt% Preferably, it is desirable to mix in an amount of 50 wt% or more and 80 wt% or less. When the mixing amount is in the above range, densification can be promoted and, at the same time, the use amount of the rare earth element can be reduced. In addition, the Nd-Fe-B based magnet powder (A) is more preferably 20 wt% to the total 100 wt% of the Nd-Fe-B based magnet powder (A) and the Nd-Fe-B based magnet powder (B) It is desirable to mix the Nd--Fe--B based magnet powder (B) in an amount of 70% to 80% by weight, more preferably in an amount of 30% to 30% by weight. When the mixing amount is in the above range, an isotropic bulk magnet having a residual magnetic flux density (Br) and a practical coercive force (Hc) can be obtained.
混合工程において、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）およびＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を混合して混合粉末を得る際、混合方法は特に限定されない。 When mixing Nd-Fe-B magnet powder (A) and Nd-Fe-B magnet powder (B) in the mixing step to obtain a mixed powder, the mixing method is not particularly limited.
（加熱工程）
本実施の形態における加熱工程においては、上記混合工程で得られた混合粉末を加圧しながら加熱して等方性バルク磁石を得る。上述のように、本実施形態では、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）とともにＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を含む混合粉末を用いるため、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の希土類元素リッチ相（Ｎｄリッチ相）によって緻密化が進み、高い相対密度を有した焼結体である等方性バルク磁石が得られる。
(Heating process)
In the heating step in the present embodiment, the mixed powder obtained in the mixing step is heated while being pressurized to obtain an isotropic bulk magnet. As described above, in the present embodiment, the Nd-Fe-B-based magnet powder (Nd-Fe-B-based magnet powder (A) and the Nd-Fe-B-based magnet powder ( Densification proceeds by the rare earth element rich phase (Nd rich phase) of B) to obtain an isotropic bulk magnet which is a sintered body having a high relative density.
加熱には、混合粉末を加圧しながら加熱できる装置を用いればよいが、このような装置としては、ホットプレス装置、ＳＰＳ装置が挙げられる。以下では、ＳＰＳ装置を例に挙げて説明する。 For heating, a device capable of heating while pressing the mixed powder may be used, and examples of such a device include a hot press device and an SPS device. Hereinafter, the SPS apparatus will be described as an example.
まず、混合粉末が入った金型をＳＰＳ装置にセットし、混合粉末に対してＯＮ−ＯＦＦ直流パルス通電を行う。電流密度は、たとえば２５０Ａ／ｃｍ２以上７００Ａ／ｃｍ２以下に設定する。 First, a mold containing mixed powder is set in an SPS apparatus, and ON-OFF direct current pulse energization is performed on the mixed powder. The current density is set to, for example, 250 A / cm 2 or more and 700 A / cm 2 or less.
加熱温度（焼結温度）は、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）が液相を形成できる温度であればよく、たとえば６００℃以上７５０℃以下であることが好ましい。上記加熱温度での保持時間は、結晶粒の成長を抑制するために５分以内とすることが望ましい。より好ましくは、変化率が０と成るところで保持なく焼結を終了するのが良い。なお、ここで変化率とは、焼結時の変位（パンチの動いた距離など）を時間微分したものである。 The heating temperature (sintering temperature) may be any temperature at which the Nd-Fe-B based magnet powder (B) can form a liquid phase, and is preferably, for example, 600 ° C. or more and 750 ° C. or less. The holding time at the above heating temperature is preferably within 5 minutes in order to suppress the growth of crystal grains. More preferably, the sintering is completed without holding at a rate of change of 0. Here, the rate of change is obtained by temporally differentiating the displacement at sintering (such as the distance the punch has moved).
加熱工程では、混合粉末を加圧しながら加熱するが、混合粉末が入った金型に対して３０ＭＰａ以上１００ＭＰａ以下の圧力を印加しながら加熱することが好ましい。また、加熱は、たとえば１０-3Ｐａ以上１０1Ｐａ以下の減圧下で行うことが好ましい。 In the heating step, the mixed powder is heated while being pressurized, but it is preferable to heat while applying a pressure of 30 MPa or more and 100 MPa or less to the mold containing the mixed powder. The heating is preferably performed under a reduced pressure of, for example, 10 −3 Pa or more and 10 1 Pa or less.
加熱して得られた等方性バルク磁石は、通常室温か取り出し可能な温度域まで冷却する。冷却は、圧力を印加しながら行ってもよく、減圧下で行ってもよい。 The isotropic bulk magnet obtained by heating is usually cooled to room temperature or a temperature range which can be taken out. The cooling may be performed while applying pressure or under reduced pressure.
加熱工程で得られた等方性バルク磁石では、希土類元素の使用量が低減されており、残留磁束密度（Ｂｒ）および実用的な保磁力（Ｈｃ）が確保されている。また、上記等方性バルク磁石は、相対密度が９０％以上１００％以下である。このように、相対密度がボンド磁石に比べて通常２０％近く向上するため、比較的残留磁束密度（Ｂｒ）の小さいＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を混合しても十分な残留磁束密度（Ｂｒ）を確保できる。 In the isotropic bulk magnet obtained in the heating step, the amount of use of the rare earth element is reduced, and the residual magnetic flux density (Br) and the practical coercive force (Hc) are secured. Moreover, the said isotropic bulk magnet is 90%-100% of a relative density. As described above, the relative density is usually improved by about 20% as compared to the bonded magnet, so that a sufficient residual magnetic flux can be obtained by mixing the Nd-Fe-B based magnet powder (B) having a relatively small residual magnetic flux density (Br). The density (Br) can be secured.
ところで、磁気特性の異なる２種類の磁石粉末を混合してボンド磁石を製造した場合、磁化曲線は各々の磁気特性を反映した形（いわゆるヘビ型の磁化曲線）となってしまう。しかし、本実施の形態の場合（すなわち、ＳＰＳ等により磁気特性の異なる２種類の磁石粉末を緻密化した場合）、静磁気相互作用が働くためヘビ型の磁化曲線にはならず、なめらかな磁化曲線となる。 By the way, when a bonded magnet is manufactured by mixing two types of magnet powders having different magnetic characteristics, the magnetization curve has a form (so-called snake-like magnetization curve) reflecting the respective magnetic characteristics. However, in the case of the present embodiment (ie, when two types of magnet powder having different magnetic properties are densified by SPS or the like), the magnetostatic interaction does not work and the magnetization curve does not have a snake-like shape, and the magnetization is smooth. It becomes a curve.
なお、加熱工程で得られた等方性バルク磁石に対して、通常後処理工程を行う。後処理工程としては、たとえば検査工程、加工工程、表面処理工程、着磁工程が挙げられる。検査工程では、加熱工程で得られた焼結体の磁気特性を振動試料型磁力計（ＶＳＭ：Vibrating Sample Magnetometer）やＢ−Ｈトレーサーなどにより検出する。ＶＳＭでは、試料を振動させ、試料の磁化によって生じる磁束の時間変化を、傍らに置いたコイルに生じる誘導起電力として検出する。また、Ｂ−Ｈトレーサーでは、試料にコイルを巻いて、外部磁界を付与した時に生じるコイルの誘導起電力を測定する。これにより、試料の磁化曲線を得る。次に、加工工程では、焼結体を切削加工ないし研磨加工し、焼結体を製品寸法に仕上げる。表面処理工程では、ニッケル（Ｎｉ）、スズ（Ｓｎ）、亜鉛（Ｚｎ）などのめっき処理、アルミ（Ａｌ）蒸着、および樹脂塗装などの表面処理を実施する。次に、着磁工程では、焼結体に公知の方法により着磁を行う。 A post-treatment step is usually performed on the isotropic bulk magnet obtained in the heating step. Examples of the post-treatment process include an inspection process, a processing process, a surface treatment process, and a magnetizing process. In the inspection step, the magnetic characteristics of the sintered body obtained in the heating step are detected by a vibrating sample magnetometer (VSM), a B-H tracer, or the like. In VSM, the sample is vibrated, and the time change of the magnetic flux generated by the magnetization of the sample is detected as an induced electromotive force generated in the coil placed aside. In the B-H tracer, a coil is wound on a sample, and the induced electromotive force of the coil generated when an external magnetic field is applied is measured. Thereby, the magnetization curve of the sample is obtained. Next, in the processing step, the sintered body is cut or polished to finish the sintered body into product dimensions. In the surface treatment step, surface treatment such as plating treatment of nickel (Ni), tin (Sn), zinc (Zn), aluminum (Al) deposition, resin coating and the like is performed. Next, in the magnetizing step, the sintered body is magnetized by a known method.
＜等方性バルク磁石＞
本実施の形態に係る等方性バルク磁石は、希土類元素が１２ａｔ％以下の量で含まれるＮｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）と、希土類元素が１２ａｔ％よりも多い量で含まれるＮｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）とを含む。
<Isotropic bulk magnet>
The isotropic bulk magnet according to the present embodiment includes the region (A) of the Nd-Fe-B based magnet containing the rare earth element in an amount of 12 at% or less, and the rare earth element in an amount larger than 12 at%. And a region (B) of the Nd-Fe-B based magnet.
このような等方性バルク磁石は、たとえば上述した製造方法において、原料となる上記粉末（Ａ）および粉末（Ｂ）を適宜選択して得ることができる。この場合、領域（Ａ）は、上記Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）に概ね由来し、領域（Ｂ）は、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）に概ね由来する。また、領域（Ａ）における元素の種類およびその含有量については、上述したＮｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）における元素の種類およびその含有量の説明で、上記粉末（Ａ）を領域（Ａ）に読み替えた説明が適用できる。同様に、領域（Ｂ）における元素の種類およびその含有量については、上述したＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）における元素の種類およびその含有量の説明で、上記粉末（Ｂ）を領域（Ｂ）に読み替えた説明が適用できる。また、領域（Ａ）および領域（Ｂ）の量比（具体的には、好ましい範囲およびその理由）については、上述したＮｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）およびＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の混合比の説明で、上記粉末（Ａ）、（Ｂ）を領域（Ａ）、（Ｂ）にそれぞれ読み替えた説明が適用できる。 Such an isotropic bulk magnet can be obtained, for example, by appropriately selecting the above-mentioned powder (A) and powder (B) as raw materials in the above-mentioned manufacturing method. In this case, the region (A) is generally derived from the Nd-Fe-B based magnet powder (A), and the region (B) is generally derived from the Nd-Fe-B based magnet powder (B). Moreover, about the kind of element in area | region (A), and its content, the description of the kind of element and its content in the Nd-Fe-B type | system | group magnet powder (A) mentioned above WHEREIN: The said powder (A) The explanation replaced with A) is applicable. Similarly, with regard to the types of elements in the region (B) and the content thereof, the above-mentioned powder (B) is a region in the description of the types of the elements in the Nd-Fe-B based magnet powder (B) and the contents thereof. The explanation replaced with (B) is applicable. In addition, the Nd-Fe-B based magnet powder (A) and the Nd-Fe-B based magnet for the ratio of the area (A) to the area (B) (specifically, preferred range and reason thereof) In the explanation of the mixing ratio of the powder (B), the explanation in which the above powders (A) and (B) are replaced with the regions (A) and (B) can be applied.
また、図１は、等方性バルク磁石の構造を説明するための図である。図１において、領域（Ａ）および領域（Ｂ）の境界には、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）に由来する希土類元素リッチな領域、たとえばＮｄリッチ相が析出していると考えられる。なお、希土類元素リッチな領域（Ｎｄリッチ相）の量は微量であるため、上述のように、領域（Ｂ）における元素の種類およびその含有量については、上記読み替えが概ね適用できる。 Moreover, FIG. 1 is a figure for demonstrating the structure of an isotropic bulk magnet. In FIG. 1, it is considered that a rare earth element rich area derived from the Nd--Fe--B based magnet powder (B), for example, an Nd-rich phase is precipitated at the boundary between the area (A) and the area (B). . In addition, since the amount of the rare earth element rich region (Nd rich phase) is very small, as described above, the above replacement can be generally applied to the kind of the element in the region (B) and the content thereof.
領域（Ａ）の大きさは、通常３０μｍ以上５００μｍ以下であり、領域（Ｂ）の大きさは、通常３０μｍ以上５００μｍ以下である。また、上記等方性バルク磁石は、相対密度が９０％以上１００％以下である。さらに、磁化曲線はヘビ型とはならない。 The size of the area (A) is usually 30 μm or more and 500 μm or less, and the size of the area (B) is usually 30 μm or more and 500 μm or less. Moreover, the said isotropic bulk magnet is 90%-100% of a relative density. Furthermore, the magnetization curve is not snake shaped.
領域の分析は、ＥＰＭＡによる領域のスポット的な組成分析や、ＳＥＭ−ＥＤＸによる面あるいは線分析による組成分析で確認することが可能である。 The analysis of the area can be confirmed by spot composition analysis of the area by EPMA, or composition analysis by surface or line analysis by SEM-EDX.
また、本実施の形態に係る等方性バルク磁石は、希土類元素が１２ａｔ％以下の量で含まれるＮｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）と、希土類元素が１２ａｔ％よりも多い量で含まれるＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）とを混合して混合粉末を得る混合工程と、上記混合工程で得られた混合粉末を加圧しながら加熱して等方性バルク磁石を得る加熱工程とを含む製造方法によって得られる等方性バルク磁石である。上記工程および得られた等方性バルク磁石の詳細については上述のとおりである。 In addition, the isotropic bulk magnet according to the present embodiment contains Nd-Fe-B based magnet powder (A) containing rare earth elements in an amount of 12 at% or less, and contains rare earth elements in an amount of more than 12 at%. Mixing step with mixed Nd-Fe-B magnet powder (B) to obtain mixed powder, and heating step to pressurize mixed powder obtained in the above mixing step to obtain isotropic bulk magnet And an isotropic bulk magnet obtained by the manufacturing method. The details of the above process and the obtained isotropic bulk magnet are as described above.
以下、実施例に基づいて本発明をさらに具体的に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be more specifically described based on examples, but the present invention is not limited to these examples.
［実施例］
＜評価方法＞
磁化曲線は、ＶＳＭまたはＢ−Ｈトレーサーによって測定した。領域の分析は、ＥＰＭＡによる領域のスポット的な組成分析、またはＳＥＭ−ＥＤＸによる面あるいは線分析による組成分析で確認した。
[Example]
<Evaluation method>
The magnetization curve was measured by VSM or B-H tracer. The analysis of the area was confirmed by spot composition analysis of the area by EPMA, or composition analysis by area or line analysis by SEM-EDX.
［実施例１］
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）（Ｎｄ含有量：１０．３ａｔ％（略１０ａｔ％）、Ｃｏ含有量：１．９ａｔ％（略２ａｔ％）、粒径：７５μｍ以上、ＭＱＰ−１５−７（商品名）、マグネクエンチ社製）５０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上、ＭＱＰ−Ｃ（商品名）、マグネクエンチ社製）５０ｗｔ％とを混合し、混合粉末を調製した。次いで、上記混合粉末を金型に入れた。この金型をＳＰＳ装置にセットし、１０-1Ｐａの減圧下で、金型に対して３０ＭＰａの圧力を印加しながら加熱した。具体的には、ＳＰＳ装置を用いて、混合粉末に対して、電流密度６００Ａ／ｃｍ２でＯＮ−ＯＦＦ直流パルス通電して昇温した。温度の上昇と共に緻密化が進行し、変化率が０になった所で焼結を終了した。この時の温度は概ね７００℃であった。
Example 1
Nd-Fe-B magnet powder (A) (Nd content: 10.3 at% (approximately 10 at%), Co content: 1.9 at% (approximately 2 at%), particle size: 75 μm or more, MQP-15- 7 (trade name), Magnequen Co., Ltd. product 50 wt%, Nd-Fe-B based magnet powder (B) (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size The mixed powder was prepared by mixing 75 μm or more and 50 wt% of MQP-C (trade name) manufactured by Magnequen Co., Ltd. The above mixed powder was then placed in a mold. The mold was set in an SPS apparatus, and was heated while applying a pressure of 30 MPa to the mold under a reduced pressure of 10 −1 Pa. Specifically, using a SPS apparatus, the mixed powder was heated by applying an ON-OFF direct current pulse at a current density of 600 A / cm 2 to raise the temperature. The densification progressed with the temperature rise, and the sintering was finished at the point where the rate of change became zero. The temperature at this time was approximately 700.degree.
また、得られた等方性バルク磁石は、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）（Ｎｄ含有量：１０．３ａｔ％（略１０ａｔ％）、Ｃｏ含有量：１．９ａｔ％（略２ａｔ％）、粒径：７５μｍ以上）５０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上）５０ｗｔ％とを含んでいた。 In addition, the obtained isotropic bulk magnet has a region (A) of Nd-Fe-B magnet (Nd content: 10.3 at% (approximately 10 at%), Co content: 1.9 at% (approximately 2 at) %), Particle size: 75 μm or more) 50 wt%, Nd-Fe-B magnet region (B) (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size: And 75 wt%).
［実施例２］
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）７０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）３０ｗｔ％とを混合し、混合粉末を調製した以外は、実施例１と同様にして等方性バルク磁石を得た。また、得られた等方性バルク磁石は、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）（Ｎｄ含有量：１０．３ａｔ％（略１０ａｔ％）、Ｃｏ含有量：１．９ａｔ％（略２ａｔ％）、粒径：７５μｍ以上）７０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上）３０ｗｔ％とを含んでいた。
Example 2
70 wt% of Nd-Fe-B based magnet powder (A) and 30 wt% of Nd-Fe-B based magnet powder (B) were mixed to prepare a mixed powder, but in the same manner as in Example 1, isotropy Bulk magnet is obtained. In addition, the obtained isotropic bulk magnet has a region (A) of Nd-Fe-B magnet (Nd content: 10.3 at% (approximately 10 at%), Co content: 1.9 at% (approximately 2 at) 70% by weight, particle size: 75 μm or more, Nd-Fe-B magnet region (B) (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size: (75 μm or more) and 30 wt%.
［実施例３］
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）６０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）４０ｗｔ％とを混合し、混合粉末を調製した以外は、実施例１と同様にして等方性バルク磁石を得た。また、得られた等方性バルク磁石は、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）（Ｎｄ含有量：１０．３ａｔ％（略１０ａｔ％）、Ｃｏ含有量：１．９ａｔ％（略２ａｔ％）、粒径：７５μｍ以上）６０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上）４０ｗｔ％とを含んでいた。
[Example 3]
60 wt% of Nd-Fe-B based magnet powder (A) and 40 wt% of Nd-Fe-B based magnet powder (B) were mixed to prepare a mixed powder, but in the same manner as Example 1, isotropy Bulk magnet is obtained. In addition, the obtained isotropic bulk magnet has a region (A) of Nd-Fe-B magnet (Nd content: 10.3 at% (approximately 10 at%), Co content: 1.9 at% (approximately 2 at) %), Particle size: 75 μm or more) 60 wt%, Nd-Fe-B magnet region (B) (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size: And 75 wt.
［実施例４］
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）４０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）６０ｗｔ％とを混合し、混合粉末を調製した以外は、実施例１と同様にして等方性バルク磁石を得た。また、得られた等方性バルク磁石は、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）（Ｎｄ含有量：１０．３ａｔ％（略１０ａｔ％）、Ｃｏ含有量：１．９ａｔ％（略２ａｔ％）、粒径：７５μｍ以上）４０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上）６０ｗｔ％とを含んでいた。
Example 4
40 wt% of Nd-Fe-B based magnet powder (A) and 60 wt% of Nd-Fe-B based magnet powder (B) were mixed to prepare a mixed powder, but in the same manner as Example 1, isotropy Bulk magnet is obtained. In addition, the obtained isotropic bulk magnet has a region (A) of Nd-Fe-B magnet (Nd content: 10.3 at% (approximately 10 at%), Co content: 1.9 at% (approximately 2 at) %), Particle size: 75 μm or more) 40 wt%, Nd-Fe-B magnet region (B) (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size: And 60 wt%).
［実施例５］
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）３０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）７０ｗｔ％とを混合し、混合粉末を調製した以外は、実施例１と同様にして等方性バルク磁石を得た。また、得られた等方性バルク磁石は、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）（Ｎｄ含有量：１０．３ａｔ％（略１０ａｔ％）、Ｃｏ含有量：１．９ａｔ％（略２ａｔ％）、粒径：７５μｍ以上）３０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上）７０ｗｔ％とを含んでいた。
[Example 5]
30% by weight of Nd-Fe-B based magnet powder (A) and 70% by weight of Nd-Fe-B based magnet powder (B) were mixed to prepare a mixed powder in the same manner as Example 1. Bulk magnet is obtained. In addition, the obtained isotropic bulk magnet has a region (A) of Nd-Fe-B magnet (Nd content: 10.3 at% (approximately 10 at%), Co content: 1.9 at% (approximately 2 at) %, Particle size: 75 μm or more) 30 wt%, Nd-Fe-B magnet region (B) (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size: And 70 wt%).
［実施例６］
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）２０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）８０ｗｔ％とを混合し、混合粉末を調製した以外は、実施例１と同様にして等方性バルク磁石を得た。また、得られた等方性バルク磁石は、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ａ）（Ｎｄ含有量：１０．３ａｔ％（略１０ａｔ％）、Ｃｏ含有量：１．９ａｔ％（略２ａｔ％）、粒径：７５μｍ以上）２０ｗｔ％と、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上）８０ｗｔ％とを含んでいた。
[Example 6]
20% by weight of Nd-Fe-B based magnet powder (A) and 80% by weight of Nd-Fe-B based magnet powder (B) were mixed to prepare a mixed powder, except that the mixed powder was prepared in the same manner as in Example 1. Bulk magnet is obtained. In addition, the obtained isotropic bulk magnet has a region (A) of Nd-Fe-B magnet (Nd content: 10.3 at% (approximately 10 at%), Co content: 1.9 at% (approximately 2 at) %, Particle size: 75 μm or more) 20 wt%, Nd-Fe-B magnet region (B) (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size: And 80% by weight).
［比較例１］
Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）を用いず、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）のみを用いた以外は、実施例１と同様にして等方性バルク磁石を得た。また、得られた等方性バルク磁石は、Ｎｄ−Ｆｅ−Ｂ系磁石の領域（Ｂ）（Ｎｄ含有量：１２．８ａｔ％（略１３ａｔ％）、Ｃｏ含有量：２０ａｔ％、粒径：７５μｍ以上）のみを含んでいた。
Comparative Example 1
An isotropic bulk magnet was obtained in the same manner as Example 1, except that the Nd-Fe-B based magnet powder (A) was not used and only the Nd-Fe-B based magnet powder (B) was used. Moreover, the obtained isotropic bulk magnet is the region (B) of Nd-Fe-B magnet (Nd content: 12.8 at% (approximately 13 at%), Co content: 20 at%, particle size: 75 μm Or more).
［比較例２］
ボンド磁石は２ｗｔ％の熱硬化性樹脂をＭＥＫで溶かしたのちに磁粉と混合し、６０℃で３０分かけてＭＥＫを揮発させた後、プレス成形にて所定の形状（φ１０ｍｍ、高さ７ｍｍ）に成形し、１９０℃、２０分で熱硬化することで作製した。
Comparative Example 2
The bond magnet dissolves 2 wt% of thermosetting resin with MEK, mixes with magnetic powder, volatilizes MEK over 30 minutes at 60 ° C, and press-molds into a specified shape (φ 10 mm, height 7 mm) And thermally cured at 190 ° C. for 20 minutes.
図１は、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の混合量に対する残留磁化および保磁力の変化を示す図である。図１より、Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の混合量が増えるにしたがって、残留磁化および保磁力が向上していることがわかる。残留磁化の上昇は、焼結体の密度の上昇と関連している。保磁力の上昇は、高保磁力のＮｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）が増えたことに起因する。 FIG. 1 is a graph showing changes in residual magnetization and coercivity with respect to the mixing amount of Nd--Fe--B based magnet powder (B). It can be seen from FIG. 1 that as the mixing amount of the Nd—Fe—B based magnet powder (B) increases, the residual magnetization and the coercivity improve. The increase in residual magnetization is associated with the increase in density of the sintered body. The increase in coercivity is attributable to the increase in the high coercivity Nd-Fe-B based magnet powder (B).
図２は、実施例１で得られた等方性バルク磁石および比較例２で得られたボンド磁石の磁化曲線を示す図である。図２より、ボンド磁石の磁化曲線がヘビ型になっていることがわかる。一方、ＳＰＳで作製した等方性バルク磁石はヘビ型が解消されていることがわかる。これは静磁気相互作用が働いているためと考えられる。このように、単体では緻密化が困難な磁石粉末も、緻密化が容易な磁石粉末と混合することにより磁気特性を保った状態で緻密化できる。 FIG. 2 is a view showing magnetization curves of the isotropic bulk magnet obtained in Example 1 and the bonded magnet obtained in Comparative Example 2. It can be seen from FIG. 2 that the magnetization curve of the bond magnet is snake-shaped. On the other hand, it can be seen that the isotropic bulk magnet produced by SPS is free of the snake shape. It is considered that this is because the magnetostatic interaction is working. As described above, even a magnet powder which is difficult to densify alone can be densified in a state where the magnetic characteristics are maintained by mixing it with the magnet powder which is easy to densify.
以上、本発明の実施の形態について説明したが、上記実施の形態により本発明が限定されるものではない。上述した各構成要素を適宜組み合わせて構成したものも本発明に含まれる。また、さらなる効果または変形例は、当業者によって容易に導き出すことができる。よって、本発明のより広範な態様は、上記実施の形態に限定されるものではなく、様々な変更が可能である。 As mentioned above, although embodiment of this invention was described, this invention is not limited by the said embodiment. The present invention also includes those configured by appropriately combining the above-described components. Also, further effects or modifications can be easily derived by one skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above embodiment, and various modifications are possible.
Claims (3)
前記混合工程で得られた混合粉末を加圧しながら加熱して等方性バルク磁石を得る加熱工程と、を含み、
前記Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）および前記Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）の粒子の粒径は、７５μｍ以上３５５μｍ以下であり、
前記混合工程が、前記Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ａ）を２０ｗｔ％以上５０ｗｔ％以下の量で、前記Ｎｄ−Ｆｅ−Ｂ系磁石粉末（Ｂ）を５０ｗｔ％以上８０ｗｔ％以下の量で混合して混合粉末を得る工程であり、
前記加熱工程が、前記混合粉末が入った金型を放電プラズマ焼結装置にセットし、該放電プラズマ焼結装置を用いて、前記金型に対して３０ＭＰａ以上１００ＭＰａ以下の圧力を印加して前記混合粉末を加圧しながら、１０ -3 Ｐａ以上１０ 1 Ｐａ以下の減圧下で、６００℃以上７５０℃以下の加熱温度で、前記加熱温度での保持時間を５分以内として、前記混合粉末を加熱して等方性バルク磁石を得る工程である、等方性バルク磁石の製造方法。 A mixture of Nd-Fe-B based magnet powder (A) containing rare earth elements in an amount of 12 at% or less and Nd-Fe-B based magnet powder (B) containing rare earth elements in an amount of more than 12 at% Mixing to obtain mixed powder;
Look including a heating step to obtain the mixed powder was heated under pressure isotropic bulk magnet obtained in the mixing step,
The particle diameter of the particles of the Nd-Fe-B magnet powder (A) and the Nd-Fe-B magnet powder (B) is 75 μm or more and 355 μm or less,
In the mixing step, the amount of the Nd-Fe-B magnet powder (A) is 20 wt% or more and 50 wt% or less, and the amount of the Nd-Fe-B magnet powder (B) is 50 wt% or more and 80 wt% or less It is the process of mixing and obtaining mixed powder
In the heating step, a mold containing the mixed powder is set in a discharge plasma sintering apparatus, and a pressure of 30 MPa or more and 100 MPa or less is applied to the mold using the discharge plasma sintering apparatus, The mixed powder is heated at a heating temperature of 600 ° C. or more and 750 ° C. or less under a reduced pressure of 10 −3 Pa or more and 10 1 Pa or less while keeping the holding time at the heating temperature within 5 minutes while pressurizing the mixed powder. A method for producing an isotropic bulk magnet , which is a step of obtaining an isotropic bulk magnet.
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