JP2682619B2 - Manufacturing method of rare earth permanent magnet - Google Patents

Manufacturing method of rare earth permanent magnet

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Publication number
JP2682619B2
JP2682619B2 JP61243214A JP24321486A JP2682619B2 JP 2682619 B2 JP2682619 B2 JP 2682619B2 JP 61243214 A JP61243214 A JP 61243214A JP 24321486 A JP24321486 A JP 24321486A JP 2682619 B2 JP2682619 B2 JP 2682619B2
Authority
JP
Japan
Prior art keywords
rare earth
permanent magnet
alloy
powder
fine powder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP61243214A
Other languages
Japanese (ja)
Other versions
JPS6398107A (en
Inventor
英樹 中村
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TDK Corp
Original Assignee
TDK Corp
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Filing date
Publication date
Application filed by TDK Corp filed Critical TDK Corp
Priority to JP61243214A priority Critical patent/JP2682619B2/en
Publication of JPS6398107A publication Critical patent/JPS6398107A/en
Application granted granted Critical
Publication of JP2682619B2 publication Critical patent/JP2682619B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/061—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder with a protective layer

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、酸化され易い希土類元素（Ｙを含む、以下
同じ）を含む希土類永久磁石用合金粉末を粉末冶金法で
永久磁石に作製する方法の改良に関するものである。 〔従来の技術〕 希土類永久磁石の中で、希土類元素、鉄およびホウ素
を必須元素とする合金（以下、Ｒ−Fe−Ｂ合金という）
は高価なCoを必須成分とせず、かつ安価なFeおよびＢを
多量に使用できるため、従来の高性能磁石の代表であっ
た希土類−コバルト磁石より原料コストが安価であり、
しかも希土類−コバルト磁石を凌ぐ高性能が期待できる
ため、その実用化に向かっての研究が活発に為されてい
る。 Ｒ−Fe−Ｂ合金磁石の製造方法の一つに粉末冶金法が
ある。この方法では、一般に合金を溶製し、造塊した
後、得られたインゴットを粗粉砕および微粉砕し、最終
的には平均粒径が数μｍの微粉末とする段階が実施され
る。かくして得られた微粉末は各種用途に合わせた形状
に成型された後に、焼結、時効等の工程を経て、永久磁
石となる。 〔発明が解決しようとする問題点〕 Ｒ−Fe−Ｂ合金は非常に酸化し易く、酸化により磁気
特性は劣化するため、パラフィン等の表面被覆剤を微粉
砕粉末と混合したり、あるいは成型時の潤滑剤であるス
テアリン酸亜鉛などを微粉砕粉末と混合するなどの工夫
により微粉末の酸化を妨げる手段が一般に採用されてい
る。しかしながら、これらの手段による処理を経て製造
されたＲ−Fe−Ｂ合金磁石には次のような問題があるこ
とに本発明者らは着目した。 （１）活性な表面の単位重量当たりの割合が極めて大で
ある微粉の状態でＲ−Fe−Ｂ合金とパラフィン、ステア
リン酸亜鉛などとを混合するために、混合前に既にかな
り酸化が進行しているか且／または混合中に酸化が進行
することに起因して、製品の酸素含有量がかなり高くな
る。かかる製品の酸素含有量を低くすると磁気特性の向
上が期待できる。 （２）パラフィン、ステアリン酸亜鉛などと微粉砕粉末
を混合するという工程が通常の粉末冶金工程に附加され
る。 〔問題点を解決するための手段〕 本発明は、上記した問題点を効果的に解決すべく、合
金粗粉材に酸化防止有機剤を混合し、乾式微粉砕を行な
い、粉砕中に粉末表面への酸化防止有機剤の被覆が進行
し、微粉砕した微粉末表面が酸化防止有機剤によって被
覆されることを特徴とし、その後通常の粉末冶金法によ
り、酸素量が少なくかつ磁気特性が優れた永久磁石を得
る希土類永久磁石の製造方法である。 本発明において、合金粗粉材および微粉材は従来、そ
れぞれ、ディスクミル、およびジェットミルにより粉砕
される平均粒径のものを指し、合金粗粉材の典型的平均
粒径は30〜60メッシュアンダーであり、微粉の典型的平
均粒径は１〜10μｍである。上記合金粗粉材の平均粒径
では、単位重量当たりの比表面積が小さいため、通常の
方法で粉砕しても酸化は少ない。かかる合金粗粉材と酸
化防止有機剤とを乳鉢あるいは混合撹拌機で混合するな
どの方法で配合し、さらに微粉砕を行なうと、微粉砕中
に酸化防止有機剤が粉末中に均一に混合されまた微粉末
の個々の粒子は表面被覆剤などにより被覆される。酸化
防止有機剤としては、従来表面被覆剤として使用されて
いるパラフィンなど、酸化からＲ−Fe−Ｂ合金を保護
し、成型工程では金型と成型体の摩擦を低減する作用を
し、焼結工程では揮散する有機物質を用いることができ
る。また従来離型剤として使用されているステアリン酸
亜鉛、ステアリン酸銅などを使用する事ができる。な
お、これらに限らず、成型中の粉末の流動、充填の障害
とならないパルチメン酸などの有機物質を使用すること
もできる。 Ｒ−Fe−Ｂ合金と酸化防止有機剤との配合量割合は特
に制限がないが、前者が多すぎると酸化防止の効果がな
く、一方後者が多すぎると成型工程に悪影響があり、ま
た燃焼ガスの処理が厄介になるため、適当なる配合量比
に調節する。その一例は、Ｒ−Fe−Ｂ合金100重量部に
対して酸化防止有機剤を0.001〜0.2重量部である。 Ｒ−Fe−Ｂ合金の組成は、本発明においては、何等制
限されない。即ち、永久磁石として有用な磁気的性質を
具備するに足る程度の希土類元素を含み、このために易
酸化性を帯びるあらゆるＲ−Fe−Ｂ合金に本発明法が適
用できる。その組成の一具体例を示すと、５〜35％R,50
〜93％Fe,2〜15％Ｂであり、Feは鉄族遷位金属で置換可
能であり、また添加元素として、V,Ta,W,Nb,Mo,Cr,Ti,H
f,Ni,Sn,Zr,Mn,Ge,Biなどを適当量添加する組成例も可
能である。希土類元素としては、Ndを始めとしてあらゆ
る元素を用いることができるが、特にミッシュメタルを
用いたＲ−Fe−Ｂ合金に本発明法を適用すると酸化防止
の効果が大きく、著しい磁気特性の改良がある。 微粉砕後の工程は通常の粉末冶金工程であり、本発明
が特徴とするところではない。唯、この工程は酸化防止
有機剤を揮散させるために、本発明において必須の工程
である。 〔作 用〕 Ｒ−Fe−Ｂ合金の粗粉と表面被覆剤などを混合しなが
ら微粉砕すると、微粉砕工程で表面被覆剤などが粉末の
表面を被覆して空気による酸化の進行を妨げ、酸化され
易い微粉が多くなるにともなって表面被覆剤が粉末をよ
り密に被覆し、表面が活性な微粉状態でのＲ−Fe−Ｂ系
合金と表面被覆剤との合金のための工程が省略され、こ
れらの作用によって、焼結磁石中の酸素量が少なくなり
そして磁気特性が向上する。 以下、実施例によりさらに具体的に本発明を説明す
る。 〔実施例〕 実施例１ Nd15B7Fe78の組成を有する合金を溶製した後、造塊
し、得られたインゴットを32メッシュ以下の粒度まで粗
粉砕を行なった。得られた粗粉に対して0.05重量％のス
テアリン酸亜鉛をN2ガス雰囲気で混合、撹拌した後、ジ
ェット・ミル粉砕を行ない、平均粒径が４μｍの微粉を
得た。 この微粉を10kOeの磁場中で1.5ton/cm2の圧力で圧粉
した後、1100℃、２時間、Arガス雰囲気中で焼結し、続
いて600℃、１時間で時効処理を行なった（試料Ａ）。 比較例１ 実施例１で得られた32メッシュ以下の粗粉をジェット
・ミル粉砕して、平均粒径が４μｍの微粉を得た。得ら
れた微粉に対して0.05重量％のステアリン酸亜鉛をN2ガ
ス雰囲気で混合、撹拌した後、実施例１と同じ条件で磁
場中成形、焼結、時効を行なった（試料Ｂ）。 実施例２ 組成が（（Ce0.7La0.3）0.5（Nd0.65Pr0.15Dy0.2）
0.5）0.17（（Fe0.97Al0.03）0.92Ｂ0.08）0.83である
合金を実施例１と同じ方法で平均粒径が４μｍの微粉に
した。この微粉を10kOeの磁場中で1.5ton/cm2の圧力で
圧粉した後、1070℃、２時間、Arガス雰囲気中で焼結
し、続いて600℃、１時間で時効処理を行なった（試料
Ｃ）。 比較例２ 実施例２の粗粉を比較例１と同様に微粉にし、得られ
た微粉に対して0.05重量％のステアリン酸亜鉛をN2ガス
雰囲気で混合、撹拌した後、実施例２と同じ条件で磁場
中成形、焼結、時効を行なった（試料Ｄ）。 試料Ａ〜Ｄの磁気特性および焼結体中の酸素量を表１
に示す。 表１に示すように、本発明の実施例では製品の酸素量
が少なくなる。唯、微粉砕前の酸化、微粉砕中の若干の
酸化、および粉末冶金工程での酸化が避けられないた
め、製品の酸素量が痕跡量になっているのではない。そ
れにも拘わらず、保磁力（iHc）および最大エネルギ積
（（BH）max）の向上はNd系Ｒ−Fe−Ｂ合金磁石および
ミッシュメタル系Ｒ−Fe−Ｂ合金磁石の両者で顕著であ
る。 〔発明の効果〕 本発明によると、Ｒ−Fe−Ｂ合金磁石の製品酸素量を
簡単かつ確実な手段で低減するとともに、磁気特性の顕
著な向上を達成できる。このためのコスト増要因は殆ど
なく、却って微粉末と表面被覆剤との混合を省略するこ
とによるコスト低減が期待できる。よって、本発明は、
Ｒ−Fe−Ｂ合金磁石の弱点である酸化による磁気特性劣
化を軽減する点で工業的に有意義である。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is a method for producing a rare earth permanent magnet alloy powder containing a rare earth element (including Y; the same applies hereinafter) that is easily oxidized into a permanent magnet by a powder metallurgy method. Related to the improvement of. [Prior Art] Among rare earth permanent magnets, an alloy containing rare earth elements, iron and boron as essential elements (hereinafter referred to as an R-Fe-B alloy).
Does not require expensive Co as an essential component and can use a large amount of inexpensive Fe and B, so the raw material cost is lower than that of the rare earth-cobalt magnet that has been a representative of conventional high-performance magnets.
Moreover, since high performance superior to that of rare earth-cobalt magnets can be expected, research for practical use thereof is being actively conducted. A powder metallurgy method is one of the methods for manufacturing an R-Fe-B alloy magnet. In this method, generally, a step is carried out in which an alloy is melted and agglomerated, and then the obtained ingot is roughly pulverized and finely pulverized to finally obtain a fine powder having an average particle diameter of several μm. The fine powder thus obtained is molded into a shape suitable for various uses, and then undergoes steps such as sintering and aging to become a permanent magnet. [Problems to be Solved by the Invention] Since the R-Fe-B alloy is very easy to oxidize and its magnetic properties deteriorate due to oxidation, a surface coating agent such as paraffin may be mixed with finely pulverized powder, or at the time of molding. A means for preventing the oxidation of the fine powder is generally adopted by devising a method such as mixing zinc stearate, which is the above-mentioned lubricant, with the finely ground powder. However, the present inventors have noticed that the R-Fe-B alloy magnet manufactured through the treatment by these means has the following problems. (1) Since the R-Fe-B alloy is mixed with paraffin, zinc stearate, etc. in a fine powder state in which the ratio of the active surface per unit weight is extremely large, oxidation has already progressed considerably before mixing. In addition, and / or due to the progress of oxidation during mixing, the oxygen content of the product is considerably higher. When the oxygen content of such a product is lowered, improvement of magnetic properties can be expected. (2) The step of mixing finely pulverized powder with paraffin, zinc stearate, etc. is added to the usual powder metallurgy step. [Means for Solving Problems] In order to effectively solve the above problems, the present invention mixes an antioxidant organic agent with an alloy coarse powder material, performs dry fine pulverization, and powder surface during pulverization. The surface of the finely ground fine powder is coated with an antioxidant organic agent as the coating progresses with an antioxidant organic agent on the It is a manufacturing method of a rare earth permanent magnet for obtaining a permanent magnet. In the present invention, the alloy coarse powder material and the fine powder material conventionally refer to those having an average particle diameter pulverized by a disc mill and a jet mill, respectively, and the typical average particle diameter of the alloy coarse powder material is 30 to 60 mesh under. And the typical average particle size of the fine powder is 1 to 10 μm. With the average particle size of the alloy coarse powder material, since the specific surface area per unit weight is small, even if it is pulverized by a usual method, the oxidation is small. Such an alloy coarse powder material and an antioxidant organic agent are mixed by a method such as mixing in a mortar or a mixing stirrer, and further finely pulverized, the antioxidant organic agent is uniformly mixed in the powder during fine pulverization. Also, individual particles of the fine powder are coated with a surface coating agent or the like. As an antioxidant organic agent, it protects the R-Fe-B alloy from oxidation such as paraffin, which has been used as a surface coating agent in the past, and in the molding process, acts to reduce friction between the mold and the molded body, and sinters it. In the process, an organic substance that volatilizes can be used. Further, zinc stearate, copper stearate and the like which have been conventionally used as a release agent can be used. Not limited to these, it is also possible to use an organic substance such as paltimic acid, which does not hinder the flow of powder during molding or the obstruction of filling. The compounding ratio of the R-Fe-B alloy and the antioxidant organic agent is not particularly limited, but if the former is too much, there is no antioxidant effect, while if the latter is too large, it has an adverse effect on the molding process, and combustion Gas treatment becomes difficult, so adjust the mixing ratio appropriately. An example thereof is 0.001 to 0.2 parts by weight of the antioxidant organic agent with respect to 100 parts by weight of the R-Fe-B alloy. The composition of the R-Fe-B alloy is not limited in the present invention. That is, the method of the present invention can be applied to any R-Fe-B alloy containing a rare earth element in an amount sufficient to have magnetic properties useful as a permanent magnet, and thus having an easily oxidizable property. A specific example of the composition is 5 to 35% R, 50
~ 93% Fe, 2 ~ 15% B, Fe can be replaced by iron group transition metal, and V, Ta, W, Nb, Mo, Cr, Ti, H as additional elements.
A composition example in which an appropriate amount of f, Ni, Sn, Zr, Mn, Ge, Bi or the like is added is also possible. As the rare earth element, any element including Nd can be used. Especially, when the method of the present invention is applied to an R—Fe—B alloy using a misch metal, the effect of preventing oxidation is great and a remarkable improvement in magnetic characteristics is achieved. is there. The process after fine pulverization is an ordinary powder metallurgy process and is not a feature of the present invention. However, this step is an essential step in the present invention in order to volatilize the antioxidant organic agent. [Operation] When the R-Fe-B alloy coarse powder and the surface coating agent are finely pulverized while being mixed, the surface coating agent and the like coat the surface of the powder in the fine pulverization step to prevent the progress of oxidation by air, The surface coating agent more densely covers the powder as the amount of fine powder that is easily oxidized increases, and the process for alloying the R-Fe-B alloy with the surface coating agent in a fine powder state where the surface is active is omitted. By these actions, the amount of oxygen in the sintered magnet is reduced and the magnetic properties are improved. Hereinafter, the present invention will be described more specifically with reference to examples. After smelted EXAMPLES alloy having the composition of Example 1 Nd 15 B 7 Fe 78, and ingot-making, resulting ingot to a particle size of less than 32 mesh was subjected to coarse grinding. 0.05% by weight of zinc stearate was mixed with the obtained coarse powder in an N 2 gas atmosphere, and the mixture was stirred and then pulverized by a jet mill to obtain fine powder having an average particle size of 4 μm. This fine powder was pressed at a pressure of 1.5 ton / cm 2 in a magnetic field of 10 kOe, then sintered at 1100 ° C. for 2 hours in an Ar gas atmosphere, and subsequently subjected to aging treatment at 600 ° C. for 1 hour ( Sample A). Comparative Example 1 The coarse powder of 32 mesh or less obtained in Example 1 was pulverized by a jet mill to obtain fine powder having an average particle size of 4 μm. 0.05% by weight of zinc stearate was mixed with the obtained fine powder in an N 2 gas atmosphere, stirred, and then molded in a magnetic field, sintered, and aged under the same conditions as in Example 1 (Sample B). Example 2 The composition was ((Ce 0.7 La 0.3 ) 0.5 (Nd 0.65 Pr 0.15 Dy 0.2 ).
An alloy of 0.5 ) 0.17 ((Fe 0.97 Al 0.03 ) 0.92 B 0.08 ) 0.83 was made into fine powder having an average particle size of 4 μm by the same method as in Example 1. This fine powder was pressed at a pressure of 1.5 ton / cm 2 in a magnetic field of 10 kOe, then sintered at 1070 ° C. for 2 hours in an Ar gas atmosphere, and subsequently subjected to aging treatment at 600 ° C. for 1 hour ( Sample C). Comparative Example 2 The coarse powder of Example 2 was pulverized in the same manner as Comparative Example 1, and 0.05% by weight of zinc stearate was mixed and stirred in the N 2 gas atmosphere with respect to the obtained fine powder, and then the same as Example 2. Under the conditions, molding in a magnetic field, sintering, and aging were performed (Sample D). Table 1 shows the magnetic properties of Samples A to D and the amount of oxygen in the sintered body.
Shown in As shown in Table 1, in the examples of the present invention, the oxygen content of the product is reduced. However, oxidation before pulverization, slight oxidation during pulverization, and oxidation in the powder metallurgy process are unavoidable, so the amount of oxygen in the product is not a trace amount. Nevertheless, the improvement of the coercive force (iHc) and the maximum energy product ((BH) max ) is remarkable in both the Nd-based R-Fe-B alloy magnet and the misch metal-based R-Fe-B alloy magnet. [Advantages of the Invention] According to the present invention, the product oxygen amount of the R-Fe-B alloy magnet can be reduced by a simple and reliable means, and the magnetic properties can be remarkably improved. There is almost no factor of cost increase for this purpose, and conversely, cost reduction can be expected by omitting the mixing of the fine powder and the surface coating agent. Therefore, the present invention
It is industrially significant in reducing deterioration of magnetic properties due to oxidation, which is a weak point of the R-Fe-B alloy magnet.

Claims (1)

(57)【特許請求の範囲】 １．希土類元素（Ｙを含む）、鉄およびホウ素を必須元
素とする合金を粗粉砕および微粉砕して、粉末冶金法に
より永久磁石を製造する方法おいて、合金粗粉材に酸化
防止有機剤を配合して乾式微粉砕を行ない、粉砕中に粉
末表面への酸化防止有機剤の被覆が進行し、微粉砕した
微粉末表面を酸化防止有機剤によって被覆して、その後
通常の粉末冶金法により、酸素量が少なくかつ磁気特性
が優れた永久磁石を得ることを特徴とする希土類永久磁
石の製造方法 ２．希土類元素がミッシュメタルである特許請求の範囲
第１項記載の希土類永久磁石の製造方法。(57) [Claims] In a method of coarsely pulverizing and finely pulverizing an alloy containing rare earth elements (including Y), iron and boron as essential elements, and producing a permanent magnet by a powder metallurgy method, an antioxidant organic agent is mixed with a coarse alloy powder material. Then, dry fine pulverization is performed, and the surface of the powder is coated with an antioxidant organic agent during the pulverization. 1. A method for producing a rare earth permanent magnet, characterized in that a permanent magnet having a small amount and excellent magnetic properties is obtained. The method for producing a rare earth permanent magnet according to claim 1, wherein the rare earth element is misch metal.
JP61243214A 1986-10-15 1986-10-15 Manufacturing method of rare earth permanent magnet Expired - Lifetime JP2682619B2 (en)

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Application Number Priority Date Filing Date Title
JP61243214A JP2682619B2 (en) 1986-10-15 1986-10-15 Manufacturing method of rare earth permanent magnet

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Application Number Priority Date Filing Date Title
JP61243214A JP2682619B2 (en) 1986-10-15 1986-10-15 Manufacturing method of rare earth permanent magnet

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Publication Number Publication Date
JPS6398107A JPS6398107A (en) 1988-04-28
JP2682619B2 true JP2682619B2 (en) 1997-11-26

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JP4716020B2 (en) * 2005-03-28 2011-07-06 Ｔｄｋ株式会社 Method for producing rare earth permanent magnet and method for mixing raw material powder and lubricant
JP4716022B2 (en) * 2005-03-30 2011-07-06 Ｔｄｋ株式会社 Rare earth permanent magnet manufacturing method
CN112413023B (en) * 2020-11-20 2022-11-08 贵州新安航空机械有限责任公司 Processing method of thin sheet powder metallurgy brake disc

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JPS6134101A (en) * 1984-07-25 1986-02-18 Sumitomo Special Metals Co Ltd Molding improving agent of alloy powder for permanent magnet

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