JP4687895B2 - Manufacturing method of rare earth sintered magnet - Google Patents
Manufacturing method of rare earth sintered magnet Download PDFInfo
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- JP4687895B2 JP4687895B2 JP2006001096A JP2006001096A JP4687895B2 JP 4687895 B2 JP4687895 B2 JP 4687895B2 JP 2006001096 A JP2006001096 A JP 2006001096A JP 2006001096 A JP2006001096 A JP 2006001096A JP 4687895 B2 JP4687895 B2 JP 4687895B2
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- Manufacturing Cores, Coils, And Magnets (AREA)
Description
本発明は、Ｎｄ−Ｆｅ−Ｂ系に代表される希土類焼結磁石の製造方法に関し、特に原料粉体を顆粒化することにより、磁場中成形時の金型への充填性を向上することにより高い生産性を得るとともに、希土類焼結磁石の小型化への対応を容易にすることのできる手法に関するものである。 The present invention relates to a method for producing a rare earth sintered magnet typified by an Nd—Fe—B system, and in particular, by granulating raw material powder, thereby improving the filling property in a mold during molding in a magnetic field. The present invention relates to a method capable of obtaining high productivity and facilitating the reduction in size of a rare earth sintered magnet.
希土類焼結磁石を製造する際、焼結に供する原料粉末を微細化することにより飽和磁束密度及び保磁力等の磁気特性を確保している。ところが、原料粉末の微細化は、成形体の寸法精度、生産性を阻害する要因となる。
原料粉末は磁場中での加圧成形により成形体を構成する。この磁場中成形において、静磁場又はパルス磁場を印加して原料粉末の粒子を配向させる。この磁場中成形時、原料粉末が微細であるほどその流動性が悪く、金型への充填性が問題となる。粉末の金型への充填性が劣ると、金型へ粉末を十分に充填することができないために成形体の寸法精度が得られない、あるいは金型への充填自体に時間がかかって生産性を阻害するという問題がある。特に薄肉形状や複雑形状の成形体を精度よくかつ効率的に作製することは困難である。
When manufacturing rare earth sintered magnets, magnetic properties such as saturation magnetic flux density and coercive force are ensured by refining the raw material powder used for sintering. However, the refinement of the raw material powder becomes a factor that hinders the dimensional accuracy and productivity of the compact.
The raw material powder forms a compact by pressure molding in a magnetic field. In the molding in the magnetic field, the raw powder particles are oriented by applying a static magnetic field or a pulse magnetic field. At the time of molding in this magnetic field, the finer the raw material powder, the worse the fluidity and the problem of filling into the mold. If the powder filling property is inferior, the powder cannot be sufficiently filled into the die, so the dimensional accuracy of the molded product cannot be obtained, or the filling of the die itself takes time and productivity. There is a problem of inhibiting. In particular, it is difficult to accurately and efficiently produce a molded body having a thin shape or a complicated shape.
原料粉末の流動性向上の手段の一つとして原料粉末の顆粒化が試みられている。例えば、特開平８−１０７０３４号公報（特許文献１）及び特開平８−８８１１１号公報（特許文献２）は希土類金属粉末にバインダを添加したスラリをスプレードライすることにより顆粒化する提案を行っている。
また、特公平７−６０２５号公報（特許文献３）は、希土類金属粉末に磁界を印加して顆粒化する提案を行っている。
Attempts have been made to granulate the raw material powder as one means for improving the fluidity of the raw material powder. For example, JP-A-8-107034 (Patent Document 1) and JP-A-8-88111 (Patent Document 2) propose to granulate by spray-drying a slurry in which a binder is added to a rare earth metal powder. Yes.
Japanese Patent Publication No. 7-6025 (Patent Document 3) proposes granulating a rare earth metal powder by applying a magnetic field.
特許文献１及び２によれば、顆粒を作製することにより流動性を向上することができる。しかし、一次合金粒子同士を例えばＰＶＡ（ポリビニルアルコール）といったバインダで付着しているため、一次合金粒子同士の付着力が比較的強い。このように付着力の強い顆粒を磁場中成形に供しても、各一次合金粒子を配向させることは容易ではない。したがって、得られる希土類焼結磁石は配向度が低く磁気特性、特に残留磁束密度（Ｂｒ）が低いものとなる。また、バインダに含まれる炭素が磁気特性低下の要因となることから、このバインダを除去する工程が必要となる。
特許文献３によれば、加圧体作製時の磁界印加工程及び顆粒を金型に充填後、磁気特性を向上させるための交流磁界印加工程を要する。また、磁界を印加した顆粒であるため残留磁化による流動性の低下が懸念される。
本発明は、このような技術的課題に基づいてなされたもので、優れた流動性を有する顆粒を用い、成形体の寸法精度の向上及び生産性の向上を図ることができる希土類焼結磁石の製造方法を提供することを目的とする。
According to
According to
The present invention has been made on the basis of such a technical problem. A rare earth sintered magnet capable of improving the dimensional accuracy and productivity of a molded body using granules having excellent fluidity. An object is to provide a manufacturing method.
上述したように、従来のバインダを用いる顆粒化技術では、バインダを溶解する溶媒として、また、一次合金粒子を分散する分散媒として、所謂有機溶媒を所定量含むスラリを作製していた。本発明者らは、この有機溶媒に着目した。その結果、有機溶媒のみで顆粒を作製することができ、この顆粒は金型充填時の流動性に優れること、さらに有機溶媒のみで作製されたこの顆粒は一次合金粒子同士の付着力が比較的弱いため、磁場中成形時に印加される磁場により一次合金粒子に分離して、良好な配向状態を実現できることを確認した。さらに有機溶媒（以下、有機液体）のみで顆粒を作製する場合、顆粒を作製するための湿分として必要とされる有機液体の量と、顆粒がその形態を維持するために必要な有機液体の量には差異があり、後者の方が少なくて済むことがわかった。有機液体は、従来のＰＶＡ等のバインダに比べて磁気特性に及ぼす影響は極めて小さいといえるが、顆粒を形成している状態の有機液体の量が希土類焼結磁石の磁気特性に影響を及ぼすことも確認された。 As described above, in the granulation technique using a conventional binder, a slurry containing a predetermined amount of a so-called organic solvent is produced as a solvent for dissolving the binder and as a dispersion medium for dispersing the primary alloy particles. The present inventors paid attention to this organic solvent. As a result, it is possible to produce a granule only with an organic solvent, the granule has excellent fluidity when filled with a mold, and the granule produced only with an organic solvent has a relatively high adhesion between primary alloy particles. Since it was weak, it was confirmed that it could be separated into primary alloy particles by a magnetic field applied during molding in a magnetic field and a good orientation state could be realized. Furthermore, when producing granules only with an organic solvent (hereinafter referred to as organic liquid), the amount of organic liquid required as moisture for producing the granules and the amount of organic liquid necessary for the granules to maintain their morphology. There was a difference in quantity, and the latter was found to be less. It can be said that the influence of the organic liquid on the magnetic properties is extremely small compared to conventional binders such as PVA, but the amount of the organic liquid in the form of granules affects the magnetic properties of the rare earth sintered magnet. Was also confirmed.
顆粒形成に必要な湿分を付与するための量だけ有機液体を添加すると、少なからずとも磁気特性を害することになる。もちろん、顆粒形成後のいずれかの段階で有機液体を除去する工程を設けることにより、磁気特性の問題を解消することはできるが、製造コストの観点からすると、この有機液体の除去工程が簡易であることが望まれる。この要求を満足させるべく、有機液体を用いて顆粒を一旦作製した後に、顆粒の形態維持に必要な量を残してその他の有機液体を除去することが本発明の目的達成に有効であろうことを知見した。
すなわち、顆粒形成後に除去の容易な有機液体と、この有機液体よりも除去の難しい有機液体を用いて顆粒を作製すれば、その後除去の容易な有機液体のみを優先的に顆粒から除去できる一方、除去が相対的に難しい有機液体を残存させることにより顆粒の形態を維持させることができるのである。そして、顆粒を用いて成形体を作製した後に、残存した有機液体を除去することにより、有機液体に基づく炭素量の低減された焼結体を得ることができる。このとき、残存した有機液体は量が既に低減されているため、成形体作製後の有機液体の除去は容易である。
If an organic liquid is added in an amount for providing moisture necessary for granule formation, the magnetic properties will be impaired at least. Of course, by providing a process for removing the organic liquid at any stage after granule formation, the problem of magnetic properties can be solved, but from the viewpoint of manufacturing cost, the organic liquid removal process is simple. It is desirable to be. In order to satisfy this requirement, it would be effective for achieving the object of the present invention to once produce a granule using an organic liquid and then remove other organic liquid while leaving an amount necessary for maintaining the shape of the granule. I found out.
In other words, if a granule is prepared using an organic liquid that is easy to remove after granule formation and an organic liquid that is more difficult to remove than the organic liquid, only the organic liquid that is easy to remove thereafter can be preferentially removed from the granule, By leaving an organic liquid that is relatively difficult to remove, the morphology of the granules can be maintained. And after producing a molded object using a granule, the sintered compact by which the carbon content based on the organic liquid was reduced can be obtained by removing the remaining organic liquid. At this time, since the amount of the remaining organic liquid has already been reduced, it is easy to remove the organic liquid after forming the molded body.
本発明は以上の知見に基づくものであって、第１の有機液体と、第１の有機液体よりも飽和蒸気圧の高い第２の有機液体を用いて所定組成の一次合金粒子を顆粒にする工程と、顆粒から第２の有機液体の除去処理を行う工程と、第２の有機液体の除去処理がなされた顆粒を金型キャビティに投入する工程と、顆粒に磁場を印加し、かつ加圧成形することにより成形体を得る工程と、成形体から第１の有機液体の除去処理行う工程と、第１の有機液体の除去処理がなされた成形体を焼結する工程と、を備えることを特徴とする希土類焼結磁石の製造方法である。本発明の希土類焼結磁石の製造方法において、第１の有機液体は、ピネン、メンタン、ターピネオールを含むテルペン系化合物、酢酸ブチルカルビトール、シクロヘキサノール、エチレングリコール、ブチルカルビトール、ジエチレングリコール、カルビトール、セロソルブ、ブチルセロソルブ、無水プロピオン酸から選択される少なくとも１つであり、第２の有機液体は、トルエン、キシレン、エタノール、アセトン、メチルイソブチルケトン、酢酸エチル、メチルエチルケトン、イソブチルアルコール、酢酸ｎ−ブチル、ジブチルエーテルから選択される少なくとも１つであるとともに、第１の有機液体および第２の有機液体の除去処理は、１００℃以下の温度域での加熱を伴う。 The present invention is based on the above knowledge, and primary alloy particles having a predetermined composition are granulated using a first organic liquid and a second organic liquid having a higher saturated vapor pressure than the first organic liquid. A step, a step of removing the second organic liquid from the granules, a step of putting the granules after the removal of the second organic liquid into the mold cavity, applying a magnetic field to the granules and pressurizing A step of obtaining a molded body by molding, a step of removing the first organic liquid from the molded body, and a step of sintering the molded body subjected to the removal treatment of the first organic liquid. It is a manufacturing method of the rare earth sintered magnet characterized. In the method for producing a rare earth sintered magnet of the present invention, the first organic liquid is a terpene compound containing pinene, menthane, terpineol, butyl carbitol, cyclohexanol, ethylene glycol, butyl carbitol, diethylene glycol, carbitol, And at least one selected from cellosolve, butyl cellosolve, and propionic anhydride, and the second organic liquid is toluene, xylene, ethanol, acetone, methyl isobutyl ketone, ethyl acetate, methyl ethyl ketone, isobutyl alcohol, n-butyl acetate, di- The removal treatment of the first organic liquid and the second organic liquid, which is at least one selected from butyl ether, involves heating in a temperature range of 100 ° C. or lower.
この希土類焼結磁石の製造方法は、第１の有機液体と第１の有機液体よりも飽和蒸気圧の高い第２の有機液体を用いて顆粒を作製しているので、加熱下で所定の減圧雰囲気に当該顆粒を晒すことにより、第２の有機液体を第１の有機液体よりも優先的に顆粒から除去することが可能となる。また、第２の有機液体の飽和蒸気圧を選択することにより、低度の減圧雰囲気で液成分を容易に除去することができるとともに、第１の有機液体を顆粒に残存させることができる。
また、成形体作製後には、第１の有機液体の除去処理を行うが、加熱下で所定の減圧雰囲気に成形体を晒すことにより、効率的に除去処理を行うことができる。ただし、第１の有機液体の除去処理は、第２の有機液体の除去処理よりも、厳しい条件、つまり減圧雰囲気の圧力を低くし、あるいは加熱温度を高くする必要があることは言うまでもない。
The method for producing a rare earth sintered magnet, since using a high first organic liquid and first saturated vapor pressure than the organic liquid second organic liquid to obtain granules, a depressurized under heating by exposing the granules to air Kiri囲, it is possible to remove the second organic liquid from the first organic liquid preferentially granules than. Further, by selecting the saturated vapor pressure of the second organic liquid, the liquid component can be easily removed in a low-pressure reduced atmosphere, and the first organic liquid can be left in the granules.
Further, after the molded body produced, but the removal process of the first organic liquid, the formed configuration at a predetermined reduced pressure atmosphere under heating by bleached Succoth, efficiently removing process can be performed. However, it goes without saying that the removal process of the first organic liquid requires stricter conditions, that is, the pressure in the reduced-pressure atmosphere or the heating temperature is higher than the removal process of the second organic liquid.
本発明において、一次合金粒子に対して、第１の有機液体を６．０ｗｔ％以下（ただし、０を含まず）、第２の有機液体を１５．０ｗｔ％以下（ただし、０を含まず）添加することが望ましい。第１の有機液体は一次合金粒子を顆粒の形態に維持するに足りる量存在していればよく、一方で第２の有機液体は顆粒作製のための湿分を確保することを意図している。 In the present invention, the first organic liquid is 6.0 wt% or less (excluding 0) and the second organic liquid is 15.0 wt% or less (excluding 0) with respect to the primary alloy particles. It is desirable to add. The first organic liquid may be present in an amount sufficient to maintain the primary alloy particles in the form of granules, while the second organic liquid is intended to ensure moisture for granule preparation. .
本発明による第２の有機液体の除去処理がなされた後の顆粒は、金型キャビティへの迅速な投入を実現するために、安息角が５０°以下であることが望ましい。
また本発明は、Ｒ２Ｔ１４Ｂ相（Ｒは希土類元素から選択される１種又は２種以上の元素、ＴはＦｅ又はＦｅ及びＣｏを含む遷移金属元素から選択される１種又は２種以上の元素）を含む組成を有し、平均粒径が２．５〜６μｍである一次合金粒子に適用することが望ましい。
The granule after the removal treatment of the second organic liquid according to the present invention desirably has an angle of repose of 50 ° or less in order to realize quick insertion into the mold cavity.
The present invention also provides an R 2 T 14 B phase (where R is one or more elements selected from rare earth elements, and T is one or two elements selected from transition metal elements including Fe, Fe, and Co). It is desirable to apply to primary alloy particles having a composition containing the above elements) and having an average particle diameter of 2.5 to 6 μm.
本発明によれば、有機液体により一次合金粒子が付着された顆粒を用いるために脱バインダ処理を行う必要がなく、成形体の寸法精度を向上しつつ希土類焼結磁石の生産性を向上することが可能となる。また、顆粒を一旦作製した後に、第２の有機液体を除去することにより、磁気特性の向上に寄与する。さらに、成形体作製後に第１の有機液体を除去することにより、炭素量が低減された焼結体を得ることができる。 According to the present invention, since it is not necessary to perform a binder removal treatment to use granules in which primary alloy particles are adhered by an organic liquid, the productivity of the rare earth sintered magnet is improved while improving the dimensional accuracy of the compact. Is possible. Further, once the granules are produced, the second organic liquid is removed, thereby contributing to improvement of magnetic properties. Furthermore, by removing the first organic liquid after forming the molded body, a sintered body with a reduced carbon content can be obtained.
以下、本発明を実施の形態に基づいて詳細に説明する。
本発明は、有機液体（特に断りがないときには、第１の有機液体及び第２の有機液体の両者を言う）により粉末同士を付着させることにより顆粒を構成する。有機液体が粒子間に存在することにより、液体架橋が生じることにより一次合金粒子同士を付着させているものと解される。有機液体による付着力は、従来のＰＶＡ等のバインダによる付着力に比べて極めて弱い。したがって、本発明による希土類焼結磁石用粉体は、磁場中成形時に印加される磁場によって容易に崩壊し一次合金粒子に分離する。そのため、高い配高度を得ることができる。これまで、バインダを用いることが顆粒作製の前提として考えられてきたが、本発明のように有機液体を用いた場合でも、流動性の高い顆粒が得られることを見出した価値は大きい。しかも、この顆粒は、磁場印加により崩壊するため、磁場中成形を行う希土類焼結磁石にとって好適である。加えて、有機液体は、従来のバインダであるＰＶＡ等の樹脂に比べて、成形体からの除去が極めて容易である。
Hereinafter, the present invention will be described in detail based on embodiments.
In the present invention, a granule is formed by adhering powders to each other with an organic liquid (referred to as both the first organic liquid and the second organic liquid unless otherwise specified). It is understood that the presence of the organic liquid between the particles causes the primary alloy particles to adhere to each other due to the occurrence of liquid crosslinking. The adhesion force due to the organic liquid is extremely weak compared to the adhesion force due to the binder such as the conventional PVA. Therefore, the rare earth sintered magnet powder according to the present invention is easily collapsed and separated into primary alloy particles by a magnetic field applied during molding in a magnetic field. Therefore, a high distribution altitude can be obtained. Up to now, the use of a binder has been considered as a premise for the production of granules. However, even when an organic liquid is used as in the present invention, it is highly valuable to find that granules with high fluidity can be obtained. Moreover, since the granules are collapsed by applying a magnetic field, they are suitable for rare earth sintered magnets that are molded in a magnetic field. In addition, the organic liquid is extremely easy to remove from the molded body as compared with a conventional binder such as PVA.
以上の有機液体を用いた顆粒化技術を適用した希土類焼結磁石の製造方法について以下で説明する。
原料合金は、真空又は不活性ガス、望ましくはＡｒ雰囲気中でストリップキャスト法、その他公知の溶解法により作製することができる。ストリップキャスト法は、原料金属をＡｒガス雰囲気などの非酸化性雰囲気中で溶解して得た溶湯を回転するロールの表面に噴出させる。ロールで急冷された溶湯は、薄板又は薄片（鱗片）状に急冷凝固される。この急冷凝固された合金は、結晶粒径が１〜５０μｍの均質な組織を有している。原料合金は、ストリップキャスト法に限らず、高周波誘導溶解等の溶解法によって得ることができる。なお、溶解後の偏析を防止するため、例えば水冷銅板に傾注して凝固させることができる。また、還元拡散法によって得られた合金を原料合金として用いることもできる。
Ｒ−Ｔ−Ｂ系焼結磁石を得る場合、Ｒ２Ｔ１４Ｂ結晶粒を主体とする合金（低Ｒ合金）と、低Ｒ合金よりＲを多く含む合金（高Ｒ合金）とを用いる所謂混合法を本発明に適用することもできる。
A method for manufacturing a rare earth sintered magnet to which the above granulation technique using an organic liquid is applied will be described below.
The raw material alloy can be produced by a strip casting method or other known melting methods in a vacuum or an inert gas, preferably in an Ar atmosphere. In the strip casting method, a molten metal obtained by melting a raw metal in a non-oxidizing atmosphere such as an Ar gas atmosphere is ejected onto the surface of a rotating roll. The melt rapidly cooled by the roll is rapidly solidified in the form of a thin plate or flakes (scales). This rapidly solidified alloy has a homogeneous structure with a crystal grain size of 1 to 50 μm. The raw material alloy can be obtained not only by the strip casting method but also by a melting method such as high frequency induction melting. In order to prevent segregation after dissolution, for example, it can be solidified by pouring into a water-cooled copper plate. An alloy obtained by the reduction diffusion method can also be used as a raw material alloy.
When obtaining an RTB-based sintered magnet, a so-called alloy using a R 2 T 14 B crystal grain (low R alloy) and an alloy containing more R than a low R alloy (high R alloy) is used. A mixing method can also be applied to the present invention.
原料合金は粉砕工程に供される。混合法による場合には、低Ｒ合金及び高Ｒ合金は別々に又は一緒に粉砕される。粉砕工程には、粗粉砕工程と微粉砕工程とがある。まず、原料合金を、粒径数百μｍ程度になるまで粗粉砕する。粗粉砕は、スタンプミル、ジョークラッシャー、ブラウンミル等を用い、不活性ガス雰囲気中にて行なうことが望ましい。粗粉砕に先立って、原料合金に水素を吸蔵させた後に放出させることにより粉砕を行なうことが効果的である。水素放出処理は、希土類焼結磁石として不純物となる水素を減少させることを目的として行われる。水素吸蔵のための加熱保持の温度は、２００℃以上、望ましくは３５０℃以上とする。保持時間は、保持温度との関係、原料合金の厚さ等によって変わるが、少なくとも３０分以上、望ましくは１時間以上とする。水素放出処理は、真空中又はＡｒガスフローにて行う。なお、水素吸蔵処理、水素放出処理は必須の処理ではない。この水素粉砕を粗粉砕と位置付けて、機械的な粗粉砕を省略することもできる。 The raw material alloy is subjected to a grinding process. In the case of the mixing method, the low R alloy and the high R alloy are pulverized separately or together. The pulverization process includes a coarse pulverization process and a fine pulverization process. First, the raw material alloy is coarsely pulverized until the particle size becomes about several hundred μm. The coarse pulverization is desirably performed in an inert gas atmosphere using a stamp mill, a jaw crusher, a brown mill or the like. Prior to coarse pulverization, it is effective to perform pulverization by allowing hydrogen to be stored in the raw material alloy and then releasing it. The hydrogen releasing treatment is performed for the purpose of reducing hydrogen as an impurity as a rare earth sintered magnet. The heating and holding temperature for storing hydrogen is 200 ° C. or higher, preferably 350 ° C. or higher. The holding time varies depending on the relationship with the holding temperature, the thickness of the raw material alloy, etc., but is at least 30 minutes or longer, preferably 1 hour or longer. The hydrogen release treatment is performed in a vacuum or Ar gas flow. The hydrogen storage process and the hydrogen release process are not essential processes. This hydrogen pulverization can be regarded as coarse pulverization, and mechanical coarse pulverization can be omitted.
粗粉砕工程後、微粉砕工程に移る。微粉砕には主にジェットミルが用いられ、粒径数百μｍ程度の粗粉砕粉末を、平均粒径２．５〜６μｍ、望ましくは３〜５μｍとする。ジェットミルは、高圧の不活性ガスを狭いノズルより開放して高速のガス流を発生させ、この高速のガス流により粗粉砕粉末を加速し、粗粉砕粉末同士の衝突やターゲットあるいは容器壁との衝突を発生させて粉砕する方法である。 After the coarse pulverization process, the process proceeds to the fine pulverization process. A jet mill is mainly used for fine pulverization, and a coarsely pulverized powder having a particle size of about several hundreds of μm has an average particle size of 2.5 to 6 μm, preferably 3 to 5 μm. The jet mill releases a high-pressure inert gas from a narrow nozzle to generate a high-speed gas flow, accelerates the coarsely pulverized powder with this high-speed gas flow, collides with the coarsely pulverized powder, and collides with the target or the container wall. It is a method of generating a collision and crushing.
混合法による場合、２種の合金の混合のタイミングは限定されるものではないが、微粉砕工程において低Ｒ合金及び高Ｒ合金を別々に粉砕した場合には、微粉砕された低Ｒ合金粉末及び高Ｒ合金粉末を窒素雰囲気中で混合する。低Ｒ合金粉末及び高Ｒ合金粉末の混合比率は、重量比で８０：２０〜９７：３程度とすればよい。低Ｒ合金及び高Ｒ合金を一緒に粉砕する場合の混合比率も同様である。なお、成形時の潤滑及び配向性の向上を目的とした脂肪酸又は脂肪酸の誘導体や炭化水素、例えばステアリン酸系やオレイン酸系であるステアリン酸亜鉛、ステアリン酸カルシウム、ステアリン酸アルミニウム、ステアリン酸アミド、オレイン酸アミド、エチレンビスイソステアリン酸アミド、炭化水素であるパラフィン、ナフタレン等を微粉砕時に０．０１〜０．３ｗｔ％程度添加することができる。 In the case of the mixing method, the timing of mixing the two kinds of alloys is not limited. However, when the low R alloy and the high R alloy are separately pulverized in the pulverization step, the pulverized low R alloy powder is used. And high R alloy powder in a nitrogen atmosphere. The mixing ratio of the low R alloy powder and the high R alloy powder may be about 80:20 to 97: 3 by weight. The mixing ratio when the low R alloy and the high R alloy are pulverized together is the same. Fatty acids or fatty acid derivatives and hydrocarbons for the purpose of improving lubrication and orientation during molding, such as zinc stearate, calcium stearate, aluminum stearate, stearamide, olein, which are stearic acid and oleic acid Acid amide, ethylenebisisostearic acid amide, hydrocarbon paraffin, naphthalene and the like can be added in an amount of about 0.01 to 0.3 wt% during pulverization.
以上で得られた微粉砕粉末を造粒して顆粒を作製する。
本発明は有機液体を用いて顆粒を作製する。本発明で用いる有機液体としては、炭化水素系化合物、アルコール系化合物、エーテル系（グリコールエーテル系を含む）化合物、エステル系（グリコールエーテル系を含む）化合物、ケトン系化合物、脂肪酸系化合物、テルペン系化合物の中から選択することができる。なお、有機液体は、一般に有機溶媒と呼ばれている物質を包含するが、本発明では溶媒として機能しないことから有機液体と呼んでいる。
Granules are produced by granulating the finely pulverized powder obtained above.
In the present invention, granules are prepared using an organic liquid. Examples of the organic liquid used in the present invention include hydrocarbon compounds, alcohol compounds, ether compounds (including glycol ether compounds), ester compounds (including glycol ether compounds), ketone compounds, fatty acid compounds, and terpene compounds. It can be selected from among compounds. The organic liquid includes a substance generally called an organic solvent, but is called an organic liquid because it does not function as a solvent in the present invention.
本発明では、第１の有機液体と、第１の有機液体よりも飽和蒸気圧の高い第２の有機液体を用いて顆粒を作製する。
表１に各種有機液体の飽和蒸気圧を示しており、この値を基準として第１の有機液体、第２の有機液体を選定すればよい。
具体的には、第１の有機液体としては、ピネン、メンタン、ターピネオールを含むテルペン系化合物、酢酸ブチルカルビトール、シクロヘキサノール、エチレングリコール、ブチルカルビトール、ジエチレングリコール、カルビトール、セロソルブ、ブチルセロソルブ、無水プロピオン酸を用いることができる。
また、第２の有機液体としては、トルエン、キシレン、エタノール、アセトン、メチルイソブチルケトン、酢酸エチル、メチルエチルケトン、イソブチルアルコール、酢酸ｎ−ブチル、ジブチルエーテルを用いることができる。
In the present invention, granules are produced using the first organic liquid and the second organic liquid having a higher saturated vapor pressure than the first organic liquid.
Table 1 shows saturated vapor pressures of various organic liquids, and the first organic liquid and the second organic liquid may be selected based on this value.
Specifically, as the first organic liquid, terpene compounds including pinene, menthane, terpineol, butyl carbitol acetate, cyclohexanol, ethylene glycol, butyl carbitol, diethylene glycol, carbitol, cellosolve, butyl cellosolve, anhydrous propion An acid can be used.
In addition, as the second organic liquid, toluene, xylene, ethanol, acetone, methyl isobutyl ketone, ethyl acetate, methyl ethyl ketone, isobutyl alcohol, n-butyl acetate, and dibutyl ether can be used .
有機液体を用いて作製された顆粒は、所定の工程までその形状を維持している必要がある。一旦作製された顆粒がその形状を維持できなくなると、顆粒から脱落した微細な一次合金粒子が顆粒の周囲に付着した形態を成し、この形態の顆粒は流動性が低下する。したがって、本発明に用いる有機液体としては、常温、常圧下において、容易に揮発しないことが望ましい。そこで本発明では、２０℃における飽和蒸気圧が７５ｍｍＨｇ(１０．０ｋＰａ)以下の有機液体を用いることが望ましい。より望ましい２０℃における飽和蒸気圧は２０ｍｍＨｇ以下、さらに望ましい２０℃における飽和蒸気圧は５ｍｍＨｇ以下である。 Granules produced using an organic liquid need to maintain their shape until a predetermined step. Once the produced granule cannot maintain its shape, fine primary alloy particles dropped from the granule form a form attached to the periphery of the granule, and the fluidity of the granule in this form decreases. Therefore, it is desirable that the organic liquid used in the present invention does not easily volatilize at room temperature and normal pressure. Therefore, in the present invention, it is desirable to use an organic liquid having a saturated vapor pressure at 20 ° C. of 75 mmHg (10.0 kPa) or less. The saturated vapor pressure at 20 ° C. is more preferably 20 mmHg or less, and the more desirable saturated vapor pressure at 20 ° C. is 5 mmHg or less.
本発明に用いる有機液体（第１の有機液体、第２の有機液体ともに）はまた、一次合金粒子間に顆粒を維持するための十分な付着力を付与する必要がある。そのために、有機液体の表面張力、粘度を特定することが本発明では望ましい。望ましい有機液体の表面張力は、２０℃において２０ｄｙｎ／ｃｍ以上である。より望ましい２０℃における表面張力は２５ｄｙｎ／ｃｍ以上、さらに望ましい２０℃における表面張力は３０ｄｙｎ／ｃｍ以上である。また、望ましい有機液体の粘度は、２０℃において０．３５ｃｐ以上である。より望ましい２０℃における粘度は１ｃｐ以上、さらに望ましい２０℃における粘度は２ｃｐ以上である。 The organic liquid used in the present invention (both the first organic liquid and the second organic liquid) must also provide sufficient adhesion to maintain the granules between the primary alloy particles. Therefore, it is desirable in the present invention to specify the surface tension and viscosity of the organic liquid. The surface tension of the desired organic liquid is 20 dyn / cm or more at 20 ° C. The more desirable surface tension at 20 ° C. is 25 dyn / cm or more, and the more desirable surface tension at 20 ° C. is 30 dyn / cm or more. The desirable viscosity of the organic liquid is 0.35 cp or more at 20 ° C. A more desirable viscosity at 20 ° C. is 1 cp or more, and a further desirable viscosity at 20 ° C. is 2 cp or more.
微粉砕粉末に対する第１の有機液体の添加量は６．０ｗｔ％以下（ただし、０を含まず）とすることが望ましい。第１の有機液体がないと液体架橋による顆粒形成が容易でなくなり、一方６．０ｗｔ％添加すれば形成された顆粒の形態維持に十分であり、それを超える添加は磁気特性を低下させる要因となる。そこで第１の有機液体の添加量は６．０ｗｔ％以下（ただし、０を含まず）とするのが望ましい。
また、第２の有機液体の添加量は１５．０ｗｔ％以下（ただし、０を含まず）とすることが望ましい。第２の有機液体がないと顆粒作製に必要な湿分を微粉砕粉末に対して与えることが難しく、１５．０ｗｔ％を超えると湿分が多くなりすぎて、第２の有機液体除去に工数がかかることになる。そこで第２の有機液体の添加量は、１５．０ｗｔ％以下（ただし、０を含まず）とすることが望ましい。より望ましい第２の有機液体の添加量は１．０〜１０．０ｗｔ％、さらに望ましい第２の有機液体の添加量は３．０〜８．０ｗｔ％以下である。
The amount of the first organic liquid added to the finely pulverized powder is preferably 6.0 wt% or less (excluding 0). Without the first organic liquid, the formation of granules by liquid cross-linking is not easy, while addition of 6.0 wt% is sufficient to maintain the shape of the formed granules, and addition exceeding this is a factor that degrades magnetic properties. Become. Therefore, the amount of the first organic liquid added is preferably 6.0 wt% or less (excluding 0).
The amount of the second organic liquid added is desirably 15.0 wt% or less (excluding 0). Without the second organic liquid, it is difficult to give the moisture necessary for granule preparation to the finely pulverized powder, and when it exceeds 15.0 wt%, the moisture becomes too much and man-hours are required for removing the second organic liquid. Will take. Therefore, the amount of the second organic liquid added is desirably 15.0 wt% or less (excluding 0). A more desirable addition amount of the second organic liquid is 1.0 to 10.0 wt%, and a more desirable addition amount of the second organic liquid is 3.0 to 8.0 wt% or less.
微粉砕粉末と有機液体とを用いて顆粒を作製する方法は、従来公知の造粒法を適用すればよい。適用できる造粒方法としては、転動造粒法、振動造粒法、混合造粒法、流動造粒法、解砕造粒法、圧縮成形造粒法、押出し造粒法、噴霧造粒法が掲げられる。微粉砕粉末と有機液体は、造粒法に応じて当該造粒法適用の前に混合、混錬される場合と、造粒法適用時に混合、混錬される場合がある。 A conventionally known granulation method may be applied as a method for producing granules using finely pulverized powder and an organic liquid. Applicable granulation methods include rolling granulation method, vibration granulation method, mixed granulation method, fluidized granulation method, disintegration granulation method, compression molding granulation method, extrusion granulation method, spray granulation method Are listed. Depending on the granulation method, the finely pulverized powder and the organic liquid may be mixed and kneaded before application of the granulation method, or may be mixed and kneaded when the granulation method is applied.
本発明では、以上のようにして作製された顆粒から第２の有機液体を除去する。有機液体は、従来のＰＶＡ等のバインダに比べると磁気特性に与える影響は極めて小さい。しかるに、有機液体に起因する炭素が少ないことが、焼結後に得られる焼結磁石の磁気特性、変形にとって好ましいことは言うまでもない。また、顆粒作製のために添加される量は、実際に顆粒の形態を維持するために最小限必要な量よりも多い。つまり、顆粒作製時には第１の有機液体に加えて第２の有機液体を添加することにより一次合金粒子全体に顆粒作製に足りる湿分を与える。このために添加される第１の有機液体及び第２の有機液体の量は、顆粒を構成するために最低限必要な湿分よりも多い。そこで本発明では、顆粒作製に必要な量を第１の有機液体と第２の有機液体の合計として添加し、顆粒を作製した後に、第２の有機液体を除去して顆粒に残存する有機液体（第１の有機液体）の量を低減しようというものである。 In the present invention, the second organic liquid is removed from the granules produced as described above. The organic liquid has a very small influence on the magnetic characteristics as compared with a conventional binder such as PVA. However, it goes without saying that a small amount of carbon resulting from the organic liquid is preferable for the magnetic properties and deformation of the sintered magnet obtained after sintering. Also, the amount added to make the granule is higher than the minimum necessary to actually maintain the granule morphology. That is, at the time of granule production, the second organic liquid is added in addition to the first organic liquid to give moisture sufficient for granule production to the entire primary alloy particles. For this purpose, the amount of the first organic liquid and the second organic liquid added is greater than the minimum moisture required to constitute the granules. Therefore, in the present invention, the amount necessary for granule production is added as the total of the first organic liquid and the second organic liquid, and after the granule is produced, the second organic liquid is removed and the organic liquid remaining in the granule is removed. This is to reduce the amount of (first organic liquid).
第２の有機液体の除去を行う具体的な手段は特に限定されないが、減圧雰囲気に顆粒を晒して揮発させることが簡易かつ効果的である。本発明では、第２の有機液体の飽和蒸気圧が第１の有機液体よりも高いため、減圧雰囲気の圧力を調整することにより、第２の有機液体のみを除去することができる。減圧雰囲気は室温であってもよいが、加熱された減圧雰囲気とすることもできる。また、大気圧での加熱によっても第２の有機液体の除去を行うことができる。 The specific means for removing the second organic liquid is not particularly limited, but it is simple and effective to volatilize the granules by exposing them to a reduced-pressure atmosphere. In the present invention, since the saturated vapor pressure of the second organic liquid is higher than that of the first organic liquid, only the second organic liquid can be removed by adjusting the pressure in the reduced pressure atmosphere. The reduced-pressure atmosphere may be room temperature, but may be a heated reduced-pressure atmosphere. The second organic liquid can also be removed by heating at atmospheric pressure.
減圧雰囲気の圧力は、第１の有機液体の飽和蒸気圧、第２の有機液体の飽和蒸気圧に応じて定める必要があるが、高すぎると第２の有機液体の揮発が十分に進まない。一方、圧力が低すぎると、有機液体の揮発が急激であるため顆粒に残存する有機液体（第１の有機液体）の量を制御するのが難しくなる。また、第１の有機液体まで揮発してしまう虞がある。そこで本発明では、第２の有機液体の除去処理では、減圧雰囲気の圧力を１０１〜１０−２Ｔｏｒｒの範囲とすることが望ましい。ただし、加熱された減圧雰囲気の場合は、７×１０２〜１０−１Ｔｏｒｒの範囲で足りる。
加熱温度が高すぎると顆粒を構成する一次合金粒子に酸化が生じ磁気特性の劣化を招くおそれがある。したがって加熱する場合には、加熱温度を４０〜８０℃とすることが望ましい。
The pressure of the reduced pressure atmosphere needs to be determined according to the saturated vapor pressure of the first organic liquid and the saturated vapor pressure of the second organic liquid, but if it is too high, the volatilization of the second organic liquid will not proceed sufficiently. On the other hand, if the pressure is too low, since the volatilization of the organic liquid is rapid, it becomes difficult to control the amount of the organic liquid (first organic liquid) remaining in the granules. Moreover, there is a possibility that even the first organic liquid may be volatilized. Therefore, in the present invention, in the second organic liquid removal process, it is desirable that the pressure of the reduced-pressure atmosphere be in the range of 10 1 to 10 −2 Torr. However, in the case of a heated reduced-pressure atmosphere, a range of 7 × 10 2 to 10 −1 Torr is sufficient.
If the heating temperature is too high, the primary alloy particles constituting the granule may be oxidized, leading to deterioration of magnetic properties. Therefore, when heating, it is desirable that the heating temperature is 40 to 80 ° C.
以上のようにして第２の有機液体が除去された顆粒に第１の有機液体が残存していないと、顆粒の形態を維持することができない。一方、顆粒に残存する第１の有機液体の量が多すぎると磁気特性維持の効果を享受することができない。そこで本発明では、顆粒に残存する第１の有機液体の量は６．０ｗｔ％以下（ただし、０を含まず）の範囲とすることが望ましい。より望ましい顆粒に残存する第１の有機液体の量は０．１〜４．０ｗｔ％、さらに望ましい顆粒に残存する第１の有機液体の量は０．２〜３．０ｗｔ％である。 If the first organic liquid does not remain in the granules from which the second organic liquid has been removed as described above, the form of the granules cannot be maintained. On the other hand, if the amount of the first organic liquid remaining in the granules is too large, the effect of maintaining magnetic properties cannot be enjoyed. Therefore, in the present invention, the amount of the first organic liquid remaining in the granules is preferably in the range of 6.0 wt% or less (however, not including 0). The amount of the first organic liquid remaining in the more desirable granules is 0.1 to 4.0 wt%, and the amount of the first organic liquid remaining in the more desirable granules is 0.2 to 3.0 wt%.
以上のようにして得られた顆粒は磁場中成形に供される。
磁場中成形における成形圧力は０．３〜３ｔｏｎ／ｃｍ２（３０〜３００ＭＰａ）の範囲とすればよい。成形圧力は成形開始から終了まで一定であってもよく、漸増又は漸減してもよく、あるいは不規則変化してもよい。成形圧力が低いほど配向性は良好となるが、成形圧力が低すぎると成形体の強度が不足してハンドリングに問題が生じるので、この点を考慮して上記範囲から成形圧力を選択する。磁場中成形で得られる成形体の最終的な相対密度は、通常、５０〜６０％である。
印加する磁場は、１２〜２０ｋＯｅ（９６０〜１６００ｋＡ／ｍ）程度とすればよい。この程度の磁場を印加することにより、顆粒は崩壊して一次合金粒子に分解される。印加する磁場は静磁場に限定されず、パルス状の磁場とすることもできる。また、静磁場とパルス状磁場を併用することもできる。
The granules obtained as described above are subjected to molding in a magnetic field.
The molding pressure in the magnetic field molding may be in the range of 0.3 to 3 ton / cm 2 (30 to 300 MPa). The molding pressure may be constant from the start to the end of molding, may increase or decrease gradually, or may vary irregularly. The lower the molding pressure is, the better the orientation is. However, if the molding pressure is too low, the strength of the molded body is insufficient and handling problems occur. Therefore, the molding pressure is selected from the above range in consideration of this point. The final relative density of the molded body obtained by molding in a magnetic field is usually 50 to 60%.
The applied magnetic field may be about 12 to 20 kOe (960 to 1600 kA / m). By applying a magnetic field of this level, the granules are broken down and decomposed into primary alloy particles. The applied magnetic field is not limited to a static magnetic field, and may be a pulsed magnetic field. A static magnetic field and a pulsed magnetic field can also be used in combination.
本発明では、次いで、成形体から第１の有機液体を除去する処理を行う。成形体作製後には第１の有機液体の存在理由がなくなるし、前述したように、有機液体に起因する炭素は少ないことが、焼結後に得られる焼結磁石の磁気特性、変形にとって好ましいからである。すなわち、炭素は希土類焼結磁石にとって不純物であり、希土類元素と反応して生成される希土類炭化物の存在は磁気特性を低下させる。また、焼結時に炭素の一部は焼結体（成形体）外に排出されるが、排出された炭素が焼結体の表面に付着すると焼結の進行を阻害する。Ｒ−Ｔ−Ｂ系焼結磁石は、焼結を真空下にて行うが、成形体を容器内に収容した状態で焼結する場合には、焼結体から排出された炭素が十分に系外に排出されないために、焼結体表面に付着することがある。このような場合には、炭素の付着量が多い部分の焼結が他の部分に比べて焼結が進行しない。例えば、直方体状の成形体を図４に示すように縦長に置いて焼結すると、その上部は側面のみならず頂面にも炭素が付着して焼結の進行の妨げとなる。このために、焼結体は図４の点線で示すような形態となる。 In the present invention, the first organic liquid is then removed from the molded body. The reason for the presence of the first organic liquid disappears after the molded body is produced, and as described above, it is preferable for the magnetic properties and deformation of the sintered magnet obtained after sintering that the carbon derived from the organic liquid is small. is there. That is, carbon is an impurity for rare earth sintered magnets, and the presence of rare earth carbides produced by reaction with rare earth elements degrades magnetic properties. Further, a part of the carbon is discharged out of the sintered body (molded body) during sintering, but if the discharged carbon adheres to the surface of the sintered body, the progress of the sintering is hindered. The RTB-based sintered magnet performs sintering under vacuum. However, when the molded body is sintered in a state of being accommodated in a container, the carbon discharged from the sintered body is sufficient. Since it is not discharged outside, it may adhere to the surface of the sintered body. In such a case, the sintering of the portion where the amount of attached carbon is large does not proceed as compared with the other portions. For example, when a rectangular parallelepiped shaped body is placed in a vertically long shape as shown in FIG. 4 and sintered, carbon adheres not only to the side surface but also to the top surface, which hinders the progress of the sintering. For this reason, a sintered compact becomes a form as shown by the dotted line of FIG.
第１の有機液体の除去処理を１００℃以下の温度域での加熱を伴うものとする以外は、第１の有機液体の除去を行う具体的な手段は特に限定されない。加熱下で、減圧雰囲気に成形体を晒して揮発させることが簡易かつ効果的である。但し、減圧することは必須ではなく、大気圧での加熱によっても第１の有機液体の除去を行うことができる。 Except that the process of removing the first organic liquid and be accompanied by heating in the temperature range of 100 ° C. or less, concrete means for removing the first organic liquid is not particularly limited. It is simple and effective to volatilize the molded body by exposing it to a reduced-pressure atmosphere under heating . However, reducing the pressure is not essential, and the first organic liquid can be removed by heating at atmospheric pressure.
減圧雰囲気の圧力は、第１の有機液体の飽和蒸気圧に応じて定める必要があるが、高すぎると第１の有機液体の揮発が十分に進まない。一方、圧力が低いことによる弊害はないが、より簡易な設備で処理を行うことが望ましい。そこで本発明では、第１の有機液体の除去処理では、減圧雰囲気の圧力を１００〜１０−５Ｔｏｒｒの範囲とすればよい。また、加熱された減圧雰囲気の場合は、１００〜１０−３Ｔｏｒｒの範囲で足りる。加熱温度が高すぎると成形体に酸化が生じ磁気特性の劣化を招くおそれがある。したがって、加熱下で減圧を行う場合には、加熱温度を４０〜１００℃とすることが望ましい。
なお、第２の有機液体の除去処理との関係でいえば、第１の有機液体の除去処理の方がより低い圧力及び／又は高い温度で処理することになる。
The pressure in the reduced pressure atmosphere needs to be determined according to the saturated vapor pressure of the first organic liquid, but if it is too high, the volatilization of the first organic liquid will not proceed sufficiently. On the other hand, although there is no harmful effect due to the low pressure, it is desirable to perform processing with simpler equipment. Therefore, in the present invention, in the first organic liquid removal process, the pressure of the reduced-pressure atmosphere may be set in the range of 10 0 to 10 −5 Torr. In the case of a heated reduced-pressure atmosphere, a range of 10 0 to 10 −3 Torr is sufficient. If the heating temperature is too high, the molded body may be oxidized and the magnetic properties may be deteriorated. Therefore , when pressure reduction is performed under heating, the heating temperature is preferably 40 to 100 ° C.
In terms of the relationship with the second organic liquid removal process, the first organic liquid removal process is performed at a lower pressure and / or higher temperature.
次いで、成形体を真空又は不活性ガス雰囲気中で焼結する。焼結温度は、組成、粉砕方法、平均粒径と粒度分布の違い等、諸条件により調整する必要があるが、１０００〜１２００℃で１〜１０時間程度焼結すればよい。なお、脱バインダと焼結を別個の工程として取り扱うこともできるが、焼結の昇温過程を脱バインダに利用することもできる。例えば、焼結における昇温過程の３００〜７００℃の温度範囲を水素雰囲気として０．２５〜３時間保持することによって脱バインダを行うことができる。
焼結後、得られた焼結体に時効処理を施すことができる。この工程は、保磁力を制御する重要な工程である。時効処理を２段に分けて行なう場合には、８００℃近傍、６００℃近傍での所定時間の保持が有効である。８００℃近傍での熱処理を焼結後に行なうと、保磁力が増大するため、混合法においては特に有効である。また、６００℃近傍の熱処理で保磁力が大きく増加するため、時効処理を１段で行なう場合には、６００℃近傍の時効処理を施すとよい。
Next, the molded body is sintered in a vacuum or an inert gas atmosphere. Although it is necessary to adjust sintering temperature by various conditions, such as a composition, a grinding | pulverization method, the difference of an average particle diameter, and a particle size distribution, what is necessary is just to sinter at 1000-1200 degreeC for about 1 to 10 hours. In addition, although a binder removal and sintering can also be handled as a separate process, the temperature rising process of sintering can also be utilized for a binder removal. For example, the binder removal can be performed by maintaining the temperature range of 300 to 700 ° C. in the temperature rising process in sintering as a hydrogen atmosphere for 0.25 to 3 hours.
After sintering, the obtained sintered body can be subjected to an aging treatment. This process is an important process for controlling the coercive force. In the case where the aging treatment is performed in two stages, holding for a predetermined time at around 800 ° C. and around 600 ° C. is effective. When the heat treatment at around 800 ° C. is performed after sintering, the coercive force increases, which is particularly effective in the mixing method. In addition, since the coercive force is greatly increased by the heat treatment at around 600 ° C., the aging treatment at around 600 ° C. is preferably performed when the aging treatment is performed in one stage.
次に本発明が適用される希土類焼結磁石について説明する。
本発明は、特にＲ−Ｔ−Ｂ系焼結磁石に適用することが望ましい。このＲ−Ｔ−Ｂ系焼結磁石は、希土類元素（Ｒ）を２５〜３７ｗｔ％含有する。ここで、本発明におけるＲはＹを含む概念を有しており、したがってＹ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕの１種又は２種以上から選択される。Ｒの量が２５ｗｔ％未満であると、Ｒ−Ｔ−Ｂ系焼結磁石の主相となるＲ２Ｔ１４Ｂ相の生成が十分ではなく軟磁性を持つα−Ｆｅなどが析出し、保磁力が著しく低下する。一方、Ｒが３７ｗｔ％を超えると主相であるＲ２Ｔ１４Ｂ相の体積比率が低下し、残留磁束密度が低下する。またＲが酸素と反応し、含有する酸素量が増え、これに伴い保磁力発生に有効なＲリッチ相が減少し、保磁力の低下を招く。したがって、Ｒの量は２５〜３７ｗｔ％とする。望ましいＲの量は２８〜３５ｗｔ％、さらに望ましいＲの量は２９〜３３ｗｔ％である。
Next, a rare earth sintered magnet to which the present invention is applied will be described.
The present invention is particularly preferably applied to an RTB-based sintered magnet. This RTB-based sintered magnet contains 25 to 37 wt% of a rare earth element (R). Here, R in the present invention has a concept including Y, and therefore 1 of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is selected from species or two or more species. If the amount of R is less than 25 wt%, the R 2 T 14 B phase, which is the main phase of the RTB-based sintered magnet, is not sufficiently generated, and α-Fe having soft magnetism is precipitated and retained. The magnetic force is significantly reduced. On the other hand, when R exceeds 37 wt%, the volume ratio of the R 2 T 14 B phase, which is the main phase, decreases, and the residual magnetic flux density decreases. Further, R reacts with oxygen, the amount of oxygen contained increases, and accordingly, the R-rich phase effective for the generation of coercive force decreases, leading to a decrease in coercive force. Therefore, the amount of R is set to 25 to 37 wt%. A desirable amount of R is 28 to 35 wt%, and a more desirable amount of R is 29 to 33 wt%.
また、本発明が適用されるＲ−Ｔ−Ｂ系焼結磁石は、ホウ素（Ｂ）を０．５〜４．５ｗｔ％含有する。Ｂが０．５ｗｔ％未満の場合には高い保磁力を得ることができない。一方で、Ｂが４．５ｗｔ％を超えると残留磁束密度が低下する傾向がある。したがって、Ｂの上限を４．５ｗｔ％とする。望ましいＢの量は０．５〜１．５ｗｔ％、さらに望ましいＢの量は０．８〜１．２ｗｔ％である。
本発明が適用されるＲ−Ｔ−Ｂ系焼結磁石は、Ｃｏを２．０ｗｔ％以下（０を含まず）、望ましくは０．１〜１．０ｗｔ％、さらに望ましくは０．３〜０．７ｗｔ％含有することができる。ＣｏはＦｅと同様の相を形成するが、キュリー温度の向上、粒界相の耐食性向上に効果がある。
Further, the RTB-based sintered magnet to which the present invention is applied contains 0.5 to 4.5 wt% of boron (B). When B is less than 0.5 wt%, a high coercive force cannot be obtained. On the other hand, when B exceeds 4.5 wt%, the residual magnetic flux density tends to decrease. Therefore, the upper limit of B is set to 4.5 wt%. A desirable amount of B is 0.5 to 1.5 wt%, and a more desirable amount of B is 0.8 to 1.2 wt%.
The RTB-based sintered magnet to which the present invention is applied has a Co content of 2.0 wt% or less (not including 0), preferably 0.1 to 1.0 wt%, more preferably 0.3 to 0. .7 wt% can be contained. Co forms the same phase as Fe, but is effective in improving the Curie temperature and improving the corrosion resistance of the grain boundary phase.
また、本発明が適用されるＲ−Ｔ−Ｂ系焼結磁石は、Ａｌ及びＣｕの１種又は２種を０．０２〜０．５ｗｔ％の範囲で含有することができる。この範囲でＡｌ及びＣｕの１種又は２種を含有させることにより、得られる焼結磁石の高保磁力化、高耐食性化、温度特性の改善が可能となる。Ａｌを添加する場合において、望ましいＡｌの量は０．０３〜０．３ｗｔ％、さらに望ましいＡｌの量は、０．０５〜０．２５ｗｔ％である。また、Ｃｕを添加する場合において、望ましいＣｕの量は０．１５ｗｔ％以下（０を含まず）、さらに望ましいＣｕの量は０．０３〜０．１２ｗｔ％である。
本発明が適用されるＲ−Ｔ−Ｂ系焼結磁石は、他の元素の含有を許容する。例えば、Ｚｒ、Ｔｉ、Ｂｉ、Ｓｎ、Ｇａ、Ｎｂ、Ｔａ、Ｓｉ、Ｖ、Ａｇ、Ｇｅ等の元素を適宜含有させることができる。一方で、酸素、窒素、炭素等の不純物元素を極力低減することが望ましい。特に磁気特性を害する酸素は、その量を５０００ｐｐｍ以下、さらには３０００ｐｐｍ以下とすることが望ましい。酸素量が多いと非磁性成分である希土類酸化物相が増大して、磁気特性を低下させるからである。
Moreover, the RTB-based sintered magnet to which the present invention is applied can contain one or two of Al and Cu in a range of 0.02 to 0.5 wt%. By containing one or two of Al and Cu in this range, it is possible to increase the coercive force, increase the corrosion resistance, and improve the temperature characteristics of the obtained sintered magnet. In the case of adding Al, the desirable amount of Al is 0.03 to 0.3 wt%, and the more desirable amount of Al is 0.05 to 0.25 wt%. Further, in the case of adding Cu, the desirable amount of Cu is 0.15 wt% or less (not including 0), and the more desirable amount of Cu is 0.03 to 0.12 wt%.
The RTB-based sintered magnet to which the present invention is applied allows the inclusion of other elements. For example, elements such as Zr, Ti, Bi, Sn, Ga, Nb, Ta, Si, V, Ag, and Ge can be appropriately contained. On the other hand, it is desirable to reduce impurity elements such as oxygen, nitrogen, and carbon as much as possible. In particular, the amount of oxygen that impairs magnetic properties is preferably 5000 ppm or less, more preferably 3000 ppm or less. This is because when the amount of oxygen is large, the rare-earth oxide phase, which is a nonmagnetic component, increases and the magnetic properties are deteriorated.
Ｒ−Ｔ−Ｂ系焼結磁石に本発明を適用することが望ましいが、他の希土類焼結磁石に本発明を適用することも可能である。例えば、Ｒ−Ｃｏ系焼結磁石に本発明を適用することもできる。
Ｒ−Ｃｏ系焼結磁石は、Ｒと、Ｆｅ、Ｎｉ、Ｍｎ及びＣｒから選ばれる１種以上の元素と、Ｃｏとを含有する。この場合、望ましくはさらにＣｕ又は、Ｎｂ、Ｚｒ、Ｔａ、Ｈｆ、Ｔｉ及びＶから選ばれる１種以上の元素を含有し、特に望ましくはＣｕと、Ｎｂ、Ｚｒ、Ｔａ、Ｈｆ、Ｔｉ及びＶから選ばれる１種以上の元素とを含有する。これらのうち特に、ＳｍとＣｏとの金属間化合物、望ましくはＳｍ２Ｃｏ１７金属間化合物を主相とし、粒界にはＳｍＣｏ５系を主体とする副相が存在する。具体的組成は、製造方法や要求される磁気特性等に応じて適宜選択すればよいが、例えば、Ｒ：２０〜３０ｗｔ％、特に２２〜２８ｗｔ％程度、Ｆｅ、Ｎｉ、Ｍｎ及びＣｒの１種以上：１〜３５ｗｔ％程度、Ｎｂ、Ｚｒ、Ｔａ、Ｈｆ、Ｔｉ及びＶの１種以上：０〜６ｗｔ％、特に０．５〜４ｗｔ％程度、Ｃｕ：０〜１０ｗｔ％、特に１〜１０ｗｔ％程度、Ｃｏ：残部の組成が望ましい。
以上、Ｒ−Ｔ−Ｂ系焼結磁石、Ｒ−Ｃｏ系焼結磁石について言及したが、本発明は他の希土類焼結磁石への適用を妨げるものではない。
Although it is desirable to apply the present invention to an RTB-based sintered magnet, the present invention can also be applied to other rare earth sintered magnets. For example, the present invention can be applied to an R—Co based sintered magnet.
The R—Co based sintered magnet contains R, one or more elements selected from Fe, Ni, Mn, and Cr, and Co. In this case, it preferably further contains at least one element selected from Cu or Nb, Zr, Ta, Hf, Ti and V, and particularly preferably from Cu and Nb, Zr, Ta, Hf, Ti and V. Containing one or more selected elements. Among these, an intermetallic compound of Sm and Co, preferably an Sm 2 Co 17 intermetallic compound, is the main phase, and a subphase mainly composed of SmCo 5 is present at the grain boundary. The specific composition may be appropriately selected according to the production method, required magnetic characteristics, and the like. For example, R: 20 to 30 wt%, particularly about 22 to 28 wt%, Fe, Ni, Mn, and Cr Above: about 1 to 35 wt%, one or more of Nb, Zr, Ta, Hf, Ti and V: 0 to 6 wt%, especially about 0.5 to 4 wt%, Cu: 0 to 10 wt%, especially 1 to 10 wt% To the extent, Co: the balance composition is desirable.
The R-T-B sintered magnet and the R-Co sintered magnet have been described above, but the present invention does not prevent application to other rare earth sintered magnets.
ストリップキャスト法により、２７．４ｗｔ％Ｎｄ−４．６ｗｔ％Ｄｙ−０．２５ｗｔ％Ａｌ−０．５ｗｔ％Ｃｏ−０．０７ｗｔ％Ｃｕ−１．０ｗｔ％Ｂ−Ｆｅの組成を有する原料合金を作製した。
次いで、室温にて原料合金に水素を吸蔵させた後、Ａｒ雰囲気中で６００℃×１時間の脱水素を行なう水素粉砕処理を行なった。
水素粉砕処理が施された合金に、粉砕性の向上並びに成形時の配向性の向上に寄与する潤滑剤を０.０５〜０.１％混合した。潤滑剤の混合は、例えばナウターミキサー等により５〜３０分間ほど行なう程度でよい。その後、ジェットミルを用いて平均粒径が５．０μｍの微粉砕粉末を得た。
A raw material alloy having a composition of 27.4 wt% Nd-4.6 wt% Dy-0.25 wt% Al-0.5 wt% Co-0.07 wt% Cu-1.0 wt% B-Fe is produced by strip casting. did.
Next, after hydrogen was occluded in the raw material alloy at room temperature, hydrogen pulverization treatment was performed in which dehydrogenation was performed at 600 ° C. for 1 hour in an Ar atmosphere.
The alloy that has been subjected to the hydrogen pulverization treatment was mixed with 0.05 to 0.1% of a lubricant that contributes to improvement of pulverization and orientation during molding. The lubricant may be mixed for about 5 to 30 minutes using, for example, a Nauter mixer. Thereafter, a finely pulverized powder having an average particle size of 5.0 μm was obtained using a jet mill.
以上の微粉砕粉末に対して、表２に示すように第１の有機液体、第２の有機液体を表２に示す量を添加した後に、乳鉢で十分に混練した。この混練物から以下のようにして顆粒を作製した。所定の間隔を隔てて、５０メッシュの篩（第１篩）と８３メッシュの篩（第２篩）を上下方向に配置した。なお、第１篩が上側に位置している。第１篩の上に、得られた混練物を載せた後に、第１篩及び第２篩をともに所定時間振動させた。振動終了後に、第２篩上に残存した顆粒を採取した。この顆粒は、第１篩及び第２篩の目開き寸法より、１８０〜３００μｍの粒径を有していることになる。これら顆粒を１Ｔｏｒｒ（１００Ｔｏｒｒ）、２５℃の雰囲気に３０分間保持した。その後、以下の方法に基づいて顆粒の安息角を測定した。その結果を表２に併せて示す。なお、表２には顆粒化する前の微粉砕粉末の安息角も併せて示している。また、作製された顆粒、顆粒作製前の微粉砕粉末の外観を図１に示す。
安息角測定方法：６０ｍｍφの円のテーブルの上に、一定高さからふるいを通して少しずつ顆粒を落下させた。顆粒の山が崩壊する直前で顆粒の供給を停止した。円テーブルの上にできた顆粒の山の底角を測定した。円テーブルを１２０°ずつ回転し、計３箇所について角度を測定し、その平均を安息角とした。
To the above finely pulverized powder, the first organic liquid and the second organic liquid were added in the amounts shown in Table 2 as shown in Table 2, and then sufficiently kneaded in a mortar. Granules were produced from the kneaded product as follows. A 50-mesh sieve (first sieve) and an 83-mesh sieve (second sieve) were arranged in the vertical direction at a predetermined interval. In addition, the 1st sieve is located on the upper side. After placing the obtained kneaded material on the first sieve, both the first sieve and the second sieve were vibrated for a predetermined time. After completion of the vibration, the granules remaining on the second sieve were collected. This granule has a particle size of 180 to 300 μm from the opening size of the first sieve and the second sieve. These granules 1Torr (10 0 Torr), and held for 30 minutes to an atmosphere of 25 ° C.. Thereafter, the angle of repose of the granules was measured based on the following method. The results are also shown in Table 2. Table 2 also shows the angle of repose of the finely pulverized powder before granulation. Moreover, the external appearance of the produced granule and the finely pulverized powder before granule production is shown in FIG.
Angle of repose measurement: Granules were dropped little by little through a sieve from a certain height on a 60 mmφ circular table. The granule supply was stopped just before the granule pile collapsed. The bottom angle of the pile of granules formed on the round table was measured. The circular table was rotated by 120 °, the angles were measured at a total of three locations, and the average was taken as the angle of repose.
得られた顆粒を磁場中成形した。具体的には、１５ｋＯｅの磁場中で１．４ｔｏｎ／ｃｍ２の圧力で成形を行い、２０×１８×５ｍｍのサイズの成形体を得た。
得られた成形体を１×１０−１Ｔｏｒｒ、５５℃の雰囲気に２０〜５０分間晒して第１の有機液体の除去を行なった。第１の有機液体の除去を行なった成形体及び第１の有機液体の除去を行なっていない成形体を真空中及びＡｒ雰囲気中で１０８０℃まで昇温し４時間保持して焼結を行った。次いで得られた焼結体に８００℃×１時間と５６０℃×１時間（ともにＡｒ雰囲気中）の２段時効処理を施した。なお、図４に示すように、成形体ＧＢを縦長の状態にして焼結を行った。
The obtained granules were molded in a magnetic field. Specifically, molding was performed at a pressure of 1.4 ton / cm 2 in a magnetic field of 15 kOe to obtain a molded body having a size of 20 × 18 × 5 mm.
The obtained molded body was exposed to an atmosphere of 1 × 10 −1 Torr and 55 ° C. for 20 to 50 minutes to remove the first organic liquid. The molded body from which the first organic liquid was removed and the molded body from which the first organic liquid was not removed were heated to 1080 ° C. in vacuum and Ar atmosphere and held for 4 hours for sintering. . Next, the obtained sintered body was subjected to a two-stage aging treatment of 800 ° C. × 1 hour and 560 ° C. × 1 hour (both in an Ar atmosphere). In addition, as shown in FIG. 4, the compact GB was sintered in a vertically long state.
得られた焼結磁石の磁気特性を測定した結果を表２に示す。なお、表２には微粉砕粉末を顆粒化することなく上記と同様にして磁場中成形、焼結及び時効処理を施して得られた焼結磁石の磁気特性も併せて示している。 Table 2 shows the results of measuring the magnetic properties of the obtained sintered magnet. Table 2 also shows the magnetic characteristics of sintered magnets obtained by subjecting the finely pulverized powder to forming, sintering, and aging treatment in a magnetic field in the same manner as described above.
表２に示すように、微粉砕粉末の安息角が６０°であるのに対して、有機液体を用いて顆粒化することにより安息角を５０°以下とし流動性を向上することができる。また、有機液体を用いた顆粒から作製された焼結磁石は、微粉砕粉末を磁場中成形して得られた焼結磁石と同等の磁気特性を備えることがわかる。
また、表２に示すように、顆粒を一度作製した後に１回目の減圧雰囲気に晒すこと（第２の有機液体除去）で、第２の有機液体としてのトルエンを除去することができるとともに、磁気特性を向上することができる。なお、１回目に減圧雰囲気に晒した後のターピネオール、トルエンの残存量を確認したところ、ターピネオールは添加した量がほとんどそのまま残存し、トルエンは全て揮発していた。
成形後、２回目の減圧雰囲気に晒すこと（第１の有機液体除去）で第１の有機液体として添加したターピネオールも全て揮発していた。
As shown in Table 2, while the angle of repose of the finely pulverized powder is 60 °, the repose angle can be reduced to 50 ° or less by granulating with an organic liquid, and the fluidity can be improved. Moreover, it turns out that the sintered magnet produced from the granule using an organic liquid is equipped with a magnetic characteristic equivalent to the sintered magnet obtained by shape | molding finely pulverized powder in a magnetic field.
In addition, as shown in Table 2, it is possible to remove toluene as the second organic liquid by exposing it to the first reduced-pressure atmosphere (second organic liquid removal) after producing granules once, and magnetically The characteristics can be improved. When the residual amounts of terpineol and toluene after first exposure to a reduced-pressure atmosphere were confirmed, the added amount of terpineol remained almost as it was, and all the toluene was volatilized.
After molding, all of the terpineol added as the first organic liquid was exposed to a second reduced pressure atmosphere (removal of the first organic liquid).
焼結後に、図４に示すように、焼結体ＳＢの最大幅と最小幅とを測定し、その差を変形量として評価した。また、焼結体ＳＢの頂面から１．０ｍｍ幅（上端部）における炭素量（Ｃ量）、高さ方向中央部における１．０ｍｍ幅（中央部）の炭素量（Ｃ量）を測定した。結果を表２に示す。
第２の有機液体の除去、さらには第１の有機液体の除去を行うことにより、焼結体上端部の炭素量が低減される。その結果、変形量が有機液体を使用することなく作製された焼結体と同等とすることができた。
After the sintering, as shown in FIG. 4, the maximum width and the minimum width of the sintered body SB were measured, and the difference was evaluated as the deformation amount. Further, the carbon amount (C amount) at a 1.0 mm width (upper end portion) from the top surface of the sintered body SB and the carbon amount (C amount) at a 1.0 mm width (center portion) at the central portion in the height direction were measured. . The results are shown in Table 2.
By removing the second organic liquid and further removing the first organic liquid, the amount of carbon at the upper end of the sintered body is reduced. As a result, the deformation amount could be equivalent to that of a sintered body produced without using an organic liquid.
表３に示す有機液体（第１の有機液体、第２の有機液体）を用いた以外は、上記と同様にして焼結磁石を得て、上記と同様にして磁気特性等を評価した。その結果を表３に示す。 Sintered magnets were obtained in the same manner as described above except that the organic liquids shown in Table 3 (first organic liquid and second organic liquid) were used, and the magnetic characteristics and the like were evaluated in the same manner as described above. The results are shown in Table 3.
表３に示すように、第１の有機液体除去処理の圧力、温度を調整することによって、処理時間を適宜変更することができる。このことは、減圧及び加熱のための設備に応じた条件によって第１の有機液体除去処理を実施できることを示唆している。 As shown in Table 3, the treatment time can be appropriately changed by adjusting the pressure and temperature of the first organic liquid removal treatment. This suggests that the first organic liquid removal treatment can be performed under conditions according to the equipment for decompression and heating.
表４に示す有機液体（第１の有機液体、第２の有機液体）を用いた以外は、上記と同様にして焼結磁石を得て、上記と同様にして安息角、磁気特性等を評価した。その結果を表４に示す。 A sintered magnet was obtained in the same manner as described above except that the organic liquids (first organic liquid and second organic liquid) shown in Table 4 were used, and the angle of repose and magnetic characteristics were evaluated in the same manner as above. did. The results are shown in Table 4.
表４に示すように、種々の第１の有機液体、第２の有機液体において、本発明の効果が得られることが証明された。また、第１の有機液体、第２の有機液体を選択することにより、常圧（７６０Ｔｏｒｒ）であっても、温度を調整すれば本発明を実施できることがわかる。 As shown in Table 4, it was proved that the effects of the present invention can be obtained in various first organic liquids and second organic liquids. In addition, it can be seen that the present invention can be implemented by adjusting the temperature even at normal pressure (760 Torr) by selecting the first organic liquid and the second organic liquid.
流動性の良い顆粒を用いるメリットとして、狭間口の金型への粉体充填性の容易さが挙げられる。それを確認するためにフィーダテストを行った。通常の量産工程において金型へ粉体を供給するためにフィーダという装置が使用される。このフィーダは、金型の上で水平方向に往復運動をする箱であり、箱の下部には供給孔が空けられている。箱の中には一定量の粉が溜められており、この箱が往復運動すると、箱下部の供給孔から金型内部に粉が落ちる仕組みになっている。流動性の良い粉ほど、一定回数の往復運動で多くの粉が落ちることになる。そこで、金型キャビティに見立てた３ｍｍ×２０ｍｍの空隙を設け、この上で、実施例１の顆粒：ターピネオール＝１．０ｗｔ％、トルエン＝６．０ｗｔ％、安息角＝４４°、及び微粉砕粉末のまま、をそれぞれ往復運動させた。往復運動のスピードは０．４ｍ／ｓとし、５往復で上記隙間に落下した粉の重量を測定した。この５往復を１回の測定対象とし、１５回の測定を繰り返した。測定結果を図２に示すが、顆粒を用いることにより、金型キャビティへの充填性を向上できることが確認された。 An advantage of using granules with good fluidity is the ease of powder filling into a narrow-mouth mold. A feeder test was conducted to confirm this. An apparatus called a feeder is used to supply powder to a mold in a normal mass production process. This feeder is a box that reciprocates horizontally on a mold, and a supply hole is formed in the lower part of the box. A certain amount of powder is stored in the box, and when this box reciprocates, the powder falls from the supply hole at the bottom of the box into the mold. The more fluid the powder, the more powder falls with a certain number of reciprocating motions. Therefore, a 3 mm × 20 mm gap is provided in the mold cavity, and on this, the granules of Example 1: terpineol = 1.0 wt%, toluene = 6.0 wt%, repose angle = 44 °, and finely pulverized powder The reciprocating motion was performed. The speed of reciprocating motion was 0.4 m / s, and the weight of the powder dropped into the gap after 5 reciprocations was measured. This five reciprocations were set as one measurement object, and 15 measurements were repeated. The measurement results are shown in FIG. 2, and it was confirmed that the filling properties into the mold cavity can be improved by using the granules.
また、金型への充填重量のばらつきを前述したフィーダを用いて評価した。評価は以下に従って行った。金型キャビティの間口を５ｍｍ×１５ｍｍとして、この上でフィーダを往復運動させてすり切り充填を行った。粉末は１０ｇ程度金型に充填されるように、深さ方向を調節した。往復運動のスピードは０．４ｍ／ｓとして粉体を充填した。使用した粉体は、上記の顆粒と顆粒化されていない微粉砕粉末である。すり切り充填をするのに、顆粒化していない微粉砕粉末は５０往復、顆粒は８往復を要した。これを５０ショット行い、重量の標準偏差σを平均重量で割ったσ／ａｖｅ．を求めた。また、縦軸に各ショットでの充填重量を平均重量で割った値（％）をとった測定結果を図３に示す。これより微粉砕粉末はすり切り充填でも重量が安定しない、すなわち流動性が悪いため金型キャビティ内で密度のばらつきがあることがわかる。 Moreover, the variation of the filling weight to a metal mold | die was evaluated using the feeder mentioned above. Evaluation was performed according to the following. The front opening of the mold cavity was set to 5 mm × 15 mm, and the feeder was reciprocated on this to perform fill-up filling. The depth direction was adjusted so that about 10 g of the powder was filled in the mold. The reciprocating speed was 0.4 m / s and the powder was filled. The used powder is the above-mentioned granule and a finely pulverized powder which is not granulated. For grinding and filling, the finely pulverized powder not granulated required 50 reciprocations and the granules required 8 reciprocations. This was performed 50 shots, and the standard deviation σ of weight was divided by the average weight σ / ave. Asked. Moreover, the measurement result which took the value (%) which divided the filling weight in each shot by the average weight on the vertical axis | shaft is shown in FIG. From this, it can be seen that the finely pulverized powder does not stabilize the weight even when it is ground and filled, that is, the fluidity is poor, so that there is a variation in density in the mold cavity.
Claims (4)
前記顆粒から前記第２の有機液体の除去処理を行う工程と、
前記第２の有機液体の除去処理がなされた前記顆粒を金型キャビティに投入する工程と、
前記顆粒に磁場を印加し、かつ加圧成形することにより成形体を得る工程と、
前記成形体から前記第１の有機液体の除去処理行う工程と、
前記第１の有機液体の除去処理がなされた前記成形体を焼結する工程と、
を備え、
前記第１の有機液体は、ピネン、メンタン、ターピネオールを含むテルペン系化合物、酢酸ブチルカルビトール、シクロヘキサノール、エチレングリコール、ブチルカルビトール、ジエチレングリコール、カルビトール、セロソルブ、ブチルセロソルブ、無水プロピオン酸から選択される少なくとも１つであり、
前記第２の有機液体は、トルエン、キシレン、エタノール、アセトン、メチルイソブチルケトン、酢酸エチル、メチルエチルケトン、イソブチルアルコール、酢酸ｎ−ブチル、ジブチルエーテルから選択される少なくとも１つであるとともに、
前記第１の有機液体および前記第２の有機液体の除去処理は、１００℃以下の温度域での加熱を伴うことを特徴とする希土類焼結磁石の製造方法。 Granulating primary alloy particles of a predetermined composition using a first organic liquid and a second organic liquid having a saturated vapor pressure higher than that of the first organic liquid;
A step of removing the second organic liquid from the granules;
Placing the granules that have been subjected to the removal treatment of the second organic liquid into a mold cavity;
Applying a magnetic field to the granules, and obtaining a molded body by pressure molding;
Removing the first organic liquid from the molded body;
Sintering the molded body that has been subjected to the removal treatment of the first organic liquid;
Equipped with a,
The first organic liquid is selected from terpene compounds including pinene, menthane, and terpineol, butyl carbitol acetate, cyclohexanol, ethylene glycol, butyl carbitol, diethylene glycol, carbitol, cellosolve, butyl cellosolve, and propionic anhydride At least one,
The second organic liquid is at least one selected from toluene, xylene, ethanol, acetone, methyl isobutyl ketone, ethyl acetate, methyl ethyl ketone, isobutyl alcohol, n-butyl acetate, dibutyl ether,
The method for producing a rare earth sintered magnet, wherein the removal treatment of the first organic liquid and the second organic liquid involves heating in a temperature range of 100 ° C. or less .
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62245604A (en) * | 1986-04-18 | 1987-10-26 | Seiko Epson Corp | Manufacture of rare earth sintered magnet |
| JPS63237402A (en) * | 1987-03-25 | 1988-10-03 | Seiko Epson Corp | Manufacture of sintered rare-earth magnet |
| JPH0457562A (en) * | 1990-06-27 | 1992-02-25 | Ricoh Co Ltd | Picture reader |
| JPH0917673A (en) * | 1995-06-26 | 1997-01-17 | Sumitomo Metal Ind Ltd | Manufacture of sintered rare earth magnet |
| JP2002294303A (en) * | 2001-03-29 | 2002-10-09 | Sumitomo Special Metals Co Ltd | METHOD FOR PRODUCING GRANULATED POWDER OF R-Fe-B BASED ALLOY AND METHOD FOR PRODUCING R-Fe-B BASED SINTERED COMPACT |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62245604A (en) * | 1986-04-18 | 1987-10-26 | Seiko Epson Corp | Manufacture of rare earth sintered magnet |
| JPS63237402A (en) * | 1987-03-25 | 1988-10-03 | Seiko Epson Corp | Manufacture of sintered rare-earth magnet |
| JPH0457562A (en) * | 1990-06-27 | 1992-02-25 | Ricoh Co Ltd | Picture reader |
| JPH0917673A (en) * | 1995-06-26 | 1997-01-17 | Sumitomo Metal Ind Ltd | Manufacture of sintered rare earth magnet |
| JP2002294303A (en) * | 2001-03-29 | 2002-10-09 | Sumitomo Special Metals Co Ltd | METHOD FOR PRODUCING GRANULATED POWDER OF R-Fe-B BASED ALLOY AND METHOD FOR PRODUCING R-Fe-B BASED SINTERED COMPACT |
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