JP2018073929A - Manufacturing method of r-t-b based sintered magnet - Google Patents
Manufacturing method of r-t-b based sintered magnet Download PDFInfo
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本開示は、Ｒ−Ｔ−Ｂ系焼結磁石（Ｒは希土類元素、ＴはＦｅまたはＦｅとＣｏ）の製造方法に関する。 The present disclosure relates to a method for producing an R-T-B based sintered magnet (R is a rare earth element, and T is Fe or Fe and Co).
Ｒ2Ｔ14Ｂ型化合物を主相とするＲ−Ｔ−Ｂ系焼結磁石は、永久磁石の中で最も高性能な磁石として知られており、ハードディスクドライブのボイスコイルモータ（ＶＣＭ）や、電気自動車用（ＥＶ、ＨＶ、ＰＨＶなど）モータ、産業機器用モータなどの各種モータや家電製品等に使用されている。 R-T-B system sintered magnets mainly composed of R 2 T 14 B-type compounds are known as the most powerful magnets among permanent magnets, and include hard disk drive voice coil motors (VCM), It is used for various motors such as motors for electric vehicles (EV, HV, PHV, etc.), motors for industrial equipment, and home appliances.
Ｒ−Ｔ−Ｂ系焼結磁石は、高温で固有保磁力ＨcJ（以下、単に「ＨcJ」と表記する）が低下するため、不可逆熱減磁が起こる。不可逆熱減磁を回避するため、モータ用等に使用する場合、高温下でも高いＨcJを維持することが要求されている。 The RTB -based sintered magnet has an irreversible thermal demagnetization because its intrinsic coercive force H cJ (hereinafter simply referred to as “H cJ ”) decreases at high temperatures. In order to avoid irreversible thermal demagnetization, it is required to maintain high H cJ even at high temperatures when used for motors and the like.
Ｒ−Ｔ−Ｂ系焼結磁石は、Ｒ2Ｔ14Ｂ型化合物相中のＲの一部を重希土類元素ＲＨ（Ｄｙ、Ｔｂ）で置換すると、ＨcJが向上することが知られている。高温で高いＨcJを得るためには、Ｒ−Ｔ−Ｂ系焼結磁石中に重希土類元素ＲＨを多く添加することが有効である。しかし、Ｒ−Ｔ−Ｂ系焼結磁石において、Ｒとして軽希土類元素ＲＬ（Ｎｄ、Ｐｒ）を重希土類元素ＲＨで置換すると、ＨcJが向上する一方、残留磁束密度Ｂr（以下、単に「Ｂr」と表記する）が低下してしまうという問題がある。 The R-T-B based sintered magnet is known to improve H cJ when a part of R in the R 2 T 14 B-type compound phase is substituted with a heavy rare earth element RH (Dy, Tb). . In order to obtain high H cJ at a high temperature, it is effective to add a large amount of heavy rare earth element RH in the RTB-based sintered magnet. However, when the light rare earth element RL (Nd, Pr) is replaced as R by the heavy rare earth element RH in the RTB-based sintered magnet, H cJ is improved, while the residual magnetic flux density B r (hereinafter simply “ There is a problem that “B r ”) is reduced.
そこで、Ｂrを低下させないように、より少ない重希土類元素ＲＨによってＲ−Ｔ−Ｂ系焼結磁石のＨcJを向上させることが検討されている。例えば、重希土類元素ＲＨのフッ化物または酸化物や、各種の金属ＭまたはＭ合金をそれぞれ単独、または混合して焼結磁石の表面に存在させ、その状態で熱処理することにより、保磁力向上に寄与する重希土類元素ＲＨを磁石内に拡散させることが提案されている。特許文献１は、Ｒフッ化物、Ｒ酸フッ化物、Ｒ酸化物の粉末をＲ−Ｔ−Ｂ系焼結磁石の表面に接触させて熱処理を行うことによりそれらを磁石内に拡散させる方法を開示している。また、出願人は特許文献２において、ＲＬＭ合金（ＭはＣｕ、Ｆｅ、Ｇａ、Ｃｏ、Ｎｉから選ばれる１種以上）の粉末と、ＲＨフッ化物の粉末をＲ−Ｔ−Ｂ系焼結磁石の表面に存在させて熱処理を行うことにより、ＲＬＭによってＲＨフッ化物を還元し、ＲＨのみを磁石内に拡散させる方法を提案した。 Therefore, so as not to reduce the B r, to improve the H cJ of the R-T-B based sintered magnets have been studied with less heavy rare-earth element RH. For example, fluoride or oxide of heavy rare earth element RH, various metals M or M alloys, either alone or mixed, are present on the surface of a sintered magnet, and heat treatment is performed in that state, thereby improving coercive force. It has been proposed to diffuse the contributing heavy rare earth element RH into the magnet. Patent Document 1 discloses a method in which powders of R fluoride, R oxyfluoride, and R oxide are brought into contact with the surface of an R-T-B system sintered magnet and subjected to heat treatment to diffuse them into the magnet. doing. In addition, the applicant described in Patent Document 2 that a powder of an RLM alloy (M is one or more selected from Cu, Fe, Ga, Co, and Ni) and an RH fluoride powder are R-T-B based sintered magnets. A method has been proposed in which the RH fluoride is reduced by RLM and only RH is diffused into the magnet by performing heat treatment in the presence of the surface.
近年、Ｒ−Ｔ−Ｂ系焼結磁石のコストダウンの要求に伴い、ＲＨ拡散源もコストダウン可能でＨcJ向上効果の高いものが望まれている。しかしながら、特許文献１や特許文献２で拡散源として使用されるＲＨフッ化物は、その製造過程で有毒なフッ酸やフッ化水素アンモニウムを使用し、生産性に問題がありコストダウンが困難である。さらに、ＲＨフッ化物中のフッ素自身は磁石中に拡散しないか拡散しても磁気特性向上の役割を果たすことが無く、ＲＨフッ化物以外のＲＨ化合物で、コストダウン可能でＨcJ向上効果の高いＲＨ拡散源が望まれている。 In recent years, along with the demand for cost reduction of RTB -based sintered magnets, RH diffusion sources that can reduce costs and have a high HcJ improvement effect are desired. However, the RH fluoride used as a diffusion source in Patent Document 1 and Patent Document 2 uses toxic hydrofluoric acid and ammonium hydrogen fluoride in the production process, and there is a problem in productivity, and cost reduction is difficult. . Furthermore, the fluorine itself in the RH fluoride does not diffuse into the magnet or plays a role in improving the magnetic properties even if diffused. The RH compound other than the RH fluoride can reduce the cost and has a high effect of improving HcJ. An RH diffusion source is desired.
本開示は、Ｒ−Ｔ−Ｂ系焼結磁石にＲＨを拡散させるための拡散源として、コストダウン可能でＨcJ向上効果の高いＲＨ拡散源を用いてＲ−Ｔ−Ｂ系焼結磁石を製造する方法を提供する。 The present disclosure relates to an RTB -based sintered magnet by using an RH diffusion source that can reduce costs and has a high effect of improving HcJ as a diffusion source for diffusing RH in the RTB -based sintered magnet. A method of manufacturing is provided.
本開示によるＲ−Ｔ−Ｂ系焼結磁石の製造方法は、例示的な実施形態において、Ｒ−Ｔ−Ｂ系焼結磁石を用意する工程と、前記Ｒ−Ｔ−Ｂ系焼結磁石の表面にＲＬＭ１Ｍ２合金（ＲＬは、Ｎｄ、Ｐｒから選ばれる１種以上、Ｍ１、Ｍ２はＣｕ、Ｆｅ、Ｇａ、Ｃｏ、Ｎｉ、Ａｌから選ばれる１種以上、Ｍ１＝Ｍ２でもよい）の粉末と、ＲＨ炭酸塩（ＲＨはＤｙおよび／またはＴｂ）の粉末とを存在させた状態において、前記Ｒ−Ｔ−Ｂ系焼結磁石の焼結温度以下で熱処理を行う工程とを含む。 In an exemplary embodiment, a method for manufacturing an RTB-based sintered magnet according to the present disclosure includes the steps of preparing an RTB-based sintered magnet, and the RTB-based sintered magnet. Powder of RLM1M2 alloy on the surface (RL is one or more selected from Nd and Pr, M1 and M2 are one or more selected from Cu, Fe, Ga, Co, Ni, and Al, and M1 = M2); And a step of performing a heat treatment at a temperature equal to or lower than the sintering temperature of the RTB-based sintered magnet in the presence of RH carbonate (RH is Dy and / or Tb) powder.
ある実施形態において、前記ＲＬＭ１Ｍ２合金はＲＬを５０原子％以上含み、かつ、前記ＲＬＭ１Ｍ２合金の融点は前記熱処理の温度以下である。 In one embodiment, the RLM1M2 alloy contains 50 atomic% or more of RL, and the melting point of the RLM1M2 alloy is equal to or lower than the temperature of the heat treatment.
ある実施形態において、前記熱処理は、前記ＲＬＭ１Ｍ２合金の粉末と前記ＲＨ炭酸塩の粉末とが、ＲＬＭ１Ｍ２合金：ＲＨ炭酸塩＝４０：６０〜９６：４の質量比率で前記Ｒ−Ｔ−Ｂ系焼結磁石の表面に存在する状態で行われる。 In one embodiment, the heat treatment is performed such that the RLM1M2 alloy powder and the RH carbonate powder are in the mass ratio of RLM1M2 alloy: RH carbonate = 40: 60 to 96: 4. It is performed in a state where it exists on the surface of the magnet.
ある実施形態では、前記Ｒ−Ｔ−Ｂ系焼結磁石の表面において、前記ＲＨ炭酸塩の粉末に含まれるＲＨ元素の質量は、Ｒ−Ｔ−Ｂ系焼結磁石に対して０．２〜１．５質量％である。 In one embodiment, the mass of the RH element contained in the RH carbonate powder on the surface of the RTB-based sintered magnet is 0.2 to 0.2 relative to the RTB-based sintered magnet. 1.5% by mass.
ある実施形態において、前記ＲＨ炭酸塩は、Ｒ−Ｔ−Ｂ系磁石のリサイクル工程によって製造されたＲＨ炭酸塩である。 In one embodiment, the RH carbonate is RH carbonate manufactured by a recycling process of an R-T-B magnet.
本開示の実施形態によると、還元作用のあるＲＬＭ１Ｍ２合金の粉末とともに、ＲＨ拡散源としてリサイクル工程によって生成され得るＲＨ炭酸塩の粉末を用いるため、希少資源を効率的に利用してコストダウンが可能であり、高温下でも高いＨcJを維持することができるＲ−Ｔ−Ｂ系焼結磁石を製造することができる。 According to the embodiment of the present disclosure, the RH carbonate powder that can be generated by the recycling process is used as the RH diffusion source together with the reducing RLM1M2 alloy powder, so that the cost can be reduced by efficiently using rare resources. Thus, an RTB -based sintered magnet capable of maintaining high H cJ even at high temperatures can be produced.
希土類元素Ｒ、特に重希土類元素ＲＨは資源存在量が少ない上、産出地が限定されているなどの理由から、供給が安定しておらず、価格が大きく変動するなどの問題を有している。そのため、近年、使用済みの廃磁石や、生産工程中に不良物として排出される磁石スクラップ、切削屑や研削屑として排出される磁石加工屑などから希土類元素Ｒを分離・回収して磁石原料として再利用するリサイクル技術が発展している。発明者は、拡散源として、リサイクル工程内で生成するＲＨ化合物を用いれば、希少なＲＨを有効活用でき、かつ、拡散源においてコストダウンが可能となると考えた。そこで、リサイクル工程内で生成するＲＨ化合物としてＲＨ炭酸塩を選択し、これを拡散源として使用する方法を検討したところ、還元能力に優れるＲＬＭ１Ｍ２合金をともに磁石表面に存在させて熱処理することにより、ＲＨ炭酸塩が還元され、ＲＨを磁石内に拡散させることができることを見出して本発明を完成した。なお、本明細書において、ＲＨを含有する物質を「拡散剤」、拡散剤のＲＨを還元して拡散し得る状態にする物質を「拡散助剤」と称する。 Rare earth elements R, particularly heavy rare earth elements RH, have a problem that their supply is not stable and their prices fluctuate greatly due to their low resource abundance and limited production areas. . Therefore, in recent years, rare earth elements R are separated and recovered from used waste magnets, magnet scraps that are discharged as defectives during the production process, magnet processing scraps that are discharged as cutting scraps and grinding scraps, etc. Recycling technology to be reused is developing. The inventor considered that if a RH compound generated in the recycling process is used as the diffusion source, the rare RH can be effectively utilized and the cost can be reduced in the diffusion source. Therefore, when RH carbonate was selected as the RH compound generated in the recycling process and a method of using this as a diffusion source was examined, by heat-treating the RLM1M2 alloy having excellent reducing ability together on the magnet surface, The present invention was completed by finding that RH carbonate was reduced and RH could diffuse into the magnet. In the present specification, a substance containing RH is referred to as a “diffusing agent”, and a substance that reduces the RH of the diffusing agent so that it can diffuse is referred to as a “diffusion aid”.
［Ｒ−Ｔ−Ｂ系焼結磁石母材の準備］
重希土類元素ＲＨの拡散の対象とするＲ−Ｔ−Ｂ系焼結磁石母材を準備する。本明細書では、わかりやすさのため、重希土類元素ＲＨの拡散の対象とするＲ−Ｔ−Ｂ系焼結磁石をＲ−Ｔ−Ｂ系焼結磁石母材と厳密に称することがあるが、「Ｒ−Ｔ−Ｂ系焼結磁石」の用語はそのような「Ｒ−Ｔ−Ｂ系焼結磁石母材」を含むものとする。このＲ−Ｔ−Ｂ系焼結磁石母材は公知のものが使用でき、例えば以下の組成を有する。
希土類元素Ｒ：１２〜１７原子％
Ｂ（Ｂ（ボロン）の一部はＣ（カーボン）で置換されていてもよい）：５〜８原子％
添加元素Ｍ´（Ａｌ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｎｉ、Ｃｕ、Ｚｎ、Ｇａ、Ｚｒ、Ｎｂ、Ｍｏ、Ａｇ、Ｉｎ、Ｓｎ、Ｈｆ、Ｔａ、Ｗ、Ｐｂ、およびＢｉからなる群から選択された少なくとも１種）：０〜２原子％
Ｔ（Ｆｅを主とする遷移金属元素であって、Ｃｏを含んでもよい）および不可避不純物：残部
[Preparation of RTB-based sintered magnet base material]
An RTB-based sintered magnet base material to be diffused of the heavy rare earth element RH is prepared. In this specification, for the sake of easy understanding, an RTB-based sintered magnet that is an object of diffusion of the heavy rare earth element RH may be strictly referred to as an RTB-based sintered magnet base material. The term “RTB-based sintered magnet” includes such an “RTB-based sintered magnet base material”. As this RTB-based sintered magnet base material, a known material can be used, for example, having the following composition.
Rare earth element R: 12-17 atom%
B (a part of B (boron) may be substituted with C (carbon)): 5 to 8 atomic%
Additive element M ′ (selected from the group consisting of Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb, and Bi At least one): 0 to 2 atomic%
T (a transition metal element mainly composed of Fe and may contain Co) and inevitable impurities: balance
ここで、希土類元素Ｒは、主として軽希土類元素ＲＬ（Ｎｄ、Ｐｒから選択される少なくとも１種の元素）であるが、重希土類元素を含有していてもよい。なお、重希土類元素を含有する場合は、ＤｙおよびＴｂの少なくとも一方を含むことが好ましい。 Here, the rare earth element R is mainly a light rare earth element RL (at least one element selected from Nd and Pr), but may contain a heavy rare earth element. In addition, when a heavy rare earth element is contained, it is preferable that at least one of Dy and Tb is included.
上記組成のＲ−Ｔ−Ｂ系焼結磁石母材は、任意の製造方法によって製造される。Ｒ−Ｔ−Ｂ系焼結磁石母材は焼結上がりでもよいし、切削加工や研磨加工が施されていてもよい。 The RTB-based sintered magnet base material having the above composition is manufactured by an arbitrary manufacturing method. The RTB-based sintered magnet base material may be sintered, or may be subjected to cutting or polishing.
［拡散剤］
拡散剤としては、ＲＨ炭酸塩（ＲＨはＤｙおよび／又はＴｂ）の粉末を用いる。ＲＨ炭酸塩の粉末の粒度は、例えば２０μｍ以下であり、小さいものは数μｍ程度である。ＲＨ炭酸塩は、Ｒ−Ｔ−Ｂ系磁石のリサイクル工程内で生成したものを用いることができる。具体的には、例えば、Ｒ−Ｔ−Ｂ系磁石の廃磁石、磁石スクラップ、磁石加工屑等から、希土類元素Ｒを回収する技術が開発されている（国際公開第２０１３／０１８７１０号）。
[Diffusion agent]
As the diffusing agent, powder of RH carbonate (RH is Dy and / or Tb) is used. The particle size of the RH carbonate powder is, for example, 20 μm or less, and a small one is about several μm. What was produced | generated within the recycle process of a R-T-B type magnet can be used for RH carbonate. Specifically, for example, a technique for recovering rare earth elements R from waste magnets, magnet scraps, magnet processing scraps, and the like of R-T-B magnets has been developed (International Publication No. 2013/018710).
このような回収技術によれば、上記のＲ−Ｔ−Ｂ系磁石の廃磁石等に種々の処理を行うことにより、ＦｅおよびＣｏから分離された希土類酸化物を得ることができる。こうして得た希土類酸化物を酸に溶解して溶媒抽出を行うと、重希土類ＲＨの溶液（ＲＨ溶液）を他の希土類元素Ｒから分離して得ることができる。ＲＨ溶液に沈殿剤として炭酸ナトリウム、重炭酸ナトリウム、炭酸アンモニウム、または重炭酸アンモニウムなどを添加すると、ＲＨ炭酸塩が沈殿する。こうして得られたＲＨ炭酸塩の粉末は、本開示におけるＲＨ拡散源として好適に用いられる。 According to such a recovery technique, a rare earth oxide separated from Fe and Co can be obtained by performing various treatments on the waste magnet of the above R-T-B magnet. When the rare earth oxide thus obtained is dissolved in an acid and subjected to solvent extraction, a heavy rare earth RH solution (RH solution) can be obtained by separating it from other rare earth elements R. When sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, or the like is added to the RH solution as a precipitant, RH carbonate precipitates. The RH carbonate powder thus obtained is suitably used as an RH diffusion source in the present disclosure.
なお、Ｒ−Ｔ−Ｂ系磁石に対して重希土類元素を外部から拡散させるために使用されたＤｙ−Ｆｅ合金またはＴｂ−Ｆｅ合金は、拡散工程中にＲ−Ｔ−Ｂ系磁石と接触して磁石中のＮｄなどの軽希土類元素Ｒを含有した状態で廃棄されることがある。このような使用済みのＲＨ拡散用合金からも、重希土類元素ＲＨを回収する技術が開発されている（国際公開第２０１４／１１５８７６号）。したがって、使用済みのＲＨ拡散用合金からも、同様にしてＲＨ炭酸塩を得ることができる。 The Dy-Fe alloy or the Tb-Fe alloy used for diffusing heavy rare earth elements from the outside to the R-T-B system magnet contacts the R-T-B system magnet during the diffusion process. In some cases, the magnet is discarded in a state containing a light rare earth element R such as Nd in the magnet. A technique for recovering heavy rare earth elements RH from such used RH diffusion alloys has also been developed (International Publication No. 2014/115876). Therefore, RH carbonate can be obtained in the same manner from a used RH diffusion alloy.
リサイクルに供されるＲ−Ｔ−Ｂ系磁石は焼結磁石に限らず、ボンド磁石や熱間加工磁石、それらに使用される磁石粉末などでもよい。もちろん、ＲＨ炭酸塩の製法はＲ−Ｔ−Ｂ系磁石のリサイクル工程に限らず、一般的な製法によってもよい。Ｒ−Ｔ−Ｂ系磁石のリサイクル工程内で生成したものを用いれば希少なＲＨを有効活用でき、かつ、拡散源においてコストダウンが可能である。 The R-T-B system magnets used for recycling are not limited to sintered magnets, but may be bonded magnets, hot-worked magnets, magnet powders used for them, or the like. Of course, the manufacturing method of the RH carbonate is not limited to the recycling process of the R-T-B magnet, and may be a general manufacturing method. By using the one generated in the recycling process of the R-T-B magnet, it is possible to effectively use rare RH and to reduce the cost at the diffusion source.
［拡散助剤］
拡散助剤としては、ＲＬＭ１Ｍ２合金の粉末を用いる。ＲＬは、Ｎｄ、Ｐｒから選ばれる１種以上、Ｍ１、Ｍ２はＣｕ、Ｆｅ、Ｇａ、Ｃｏ、Ｎｉ、Ａｌから選ばれる１種以上であり、Ｍ１＝Ｍ２でもよい。ＲＬＭ１Ｍ２合金の典型例は、ＮｄＣｕ合金、ＮｄＦｅ合金、ＮｄＣｕＡｌ合金、ＮｄＣｕＣｏ合金、ＮｄＣｏＧａ合金、ＮｄＰｒＣｕ合金、ＮｄＰｒＦｅ合金などである。これらの合金の粉末は、上述のＲＨ炭酸塩粉末と混合して用いられる。複数種のＲＬＭ１Ｍ２合金粉末とＲＨ炭酸塩粉末を混合して用いてもよい。ＲＬＭ１Ｍ２合金の粉末の作製方法は特に限定されない。急冷法または鋳造法で作製される場合、粉砕性を良くするために、Ｍ１≠Ｍ２とし、例えば、ＮｄＣｕＡｌ合金、ＮｄＣｕＣｏ合金、ＮｄＣｏＧａ合金などの３元系以上の合金を採用することが好ましい。ＲＬＭ１Ｍ２合金粉末の粒度は、例えば５００μｍ以下であり、小さいものは１０μｍ程度である。
[Diffusion aid]
As a diffusion aid, RLM1M2 alloy powder is used. RL is one or more selected from Nd and Pr, M1 and M2 are one or more selected from Cu, Fe, Ga, Co, Ni, and Al, and M1 = M2. Typical examples of the RLM1M2 alloy are NdCu alloy, NdFe alloy, NdCuAl alloy, NdCuCo alloy, NdCoGa alloy, NdPrCu alloy, NdPrFe alloy and the like. These alloy powders are used by mixing with the above-mentioned RH carbonate powder. A plurality of types of RLM1M2 alloy powder and RH carbonate powder may be mixed and used. The method for producing the RLM1M2 alloy powder is not particularly limited. When manufactured by a rapid cooling method or a casting method, in order to improve pulverizability, it is preferable to set M1 ≠ M2, and employ, for example, a ternary or higher alloy such as an NdCuAl alloy, an NdCuCo alloy, or an NdCoGa alloy. The particle size of the RLM1M2 alloy powder is, for example, 500 μm or less, and the smaller one is about 10 μm.
［塗布］
ＲＬＭ１Ｍ２合金の粉末とＲＨ炭酸塩の粉末とをＲ−Ｔ−Ｂ系焼結磁石の表面に存在させる方法はどのようなものであってもよい。例えば、ＲＬＭ１Ｍ２合金の粉末とＲＨ炭酸塩の粉末をＲ−Ｔ−Ｂ系焼結磁石の表面に散布する方法や、ＲＬＭ１Ｍ２合金の粉末とＲＨ炭酸塩の粉末とを純水や有機溶剤などの溶媒に分散させ、これにＲ−Ｔ−Ｂ系焼結磁石を浸漬して引き上げる方法、ＲＬＭ１Ｍ２合金の粉末とＲＨ炭酸塩の粉末とをバインダーや溶媒と混合してスラリーを作製し、このスラリーをＲ−Ｔ−Ｂ系焼結磁石の表面に塗布する方法、ＲＬＭ１Ｍ２合金の粉末とＲＨ炭酸塩の粉末をバインダーと共に造粒して造粒粉末を作製し、この造粒粉末をＲ−Ｔ−Ｂ系焼結磁石の表面に付着させる方法、等が挙げられる。バインダーや溶媒は、その後の熱処理の昇温過程において、拡散助剤の融点以下の温度で熱分解や蒸発などでＲ−Ｔ−Ｂ系焼結磁石の表面から実質的に除去されるものであればよく、特に限定されるものではない。バインダーの例としては、ポリビニルアルコール、エチルセルロース、ポリエステルなどがあげられる。またＲＬＭ１Ｍ２合金の粉末とＲＨ炭酸塩の粉末は、それらが混合した状態でＲ−Ｔ−Ｂ系焼結磁石の表面に存在させてもよいし、別々に存在させてもよい。なお、本開示の方法においては、ＲＬＭ１Ｍ２合金はその融点が熱処理温度以下であるため熱処理の際に溶融し、Ｒ−Ｔ−Ｂ系焼結磁石の表面は還元されたＲＨがＲ−Ｔ−Ｂ系焼結磁石内部に拡散しやすい状態になる。したがって、ＲＬＭ１Ｍ２合金の粉末とＲＨ炭酸塩の粉末とをＲ−Ｔ−Ｂ系焼結磁石の表面に存在させる前にＲ−Ｔ−Ｂ系焼結磁石の表面に対して酸洗などの特段の清浄化処理を行う必要はない。もちろん、そのような清浄化処理を行うことを排除するものではない。また、ＲＬＭ１Ｍ２合金粉末粒子の表面が多少酸化されていてもＲＨ炭酸塩を還元する効果にほとんど影響はない。
[Application]
Any method may be used in which the RLM1M2 alloy powder and the RH carbonate powder are present on the surface of the R-T-B system sintered magnet. For example, a method of spraying RLM1M2 alloy powder and RH carbonate powder on the surface of an R-T-B system sintered magnet, or a solvent such as pure water or an organic solvent using RLM1M2 alloy powder and RH carbonate powder. A method in which an RTB-based sintered magnet is immersed and pulled up in this, a powder of RLM1M2 alloy and a powder of RH carbonate are mixed with a binder or a solvent to prepare a slurry. A method of applying to the surface of a TB sintered magnet, granulating a powder of RLM1M2 alloy and RH carbonate together with a binder to produce a granulated powder, and this granulated powder is converted to an RTB system. The method of adhering to the surface of a sintered magnet, etc. are mentioned. The binder or solvent should be substantially removed from the surface of the RTB-based sintered magnet by thermal decomposition or evaporation at a temperature lower than the melting point of the diffusion aid in the subsequent heating process. There is no particular limitation. Examples of the binder include polyvinyl alcohol, ethyl cellulose, polyester and the like. The RLM1M2 alloy powder and the RH carbonate powder may be present on the surface of the RTB-based sintered magnet in a state where they are mixed, or may be present separately. In the method of the present disclosure, since the melting point of the RLM1M2 alloy is equal to or lower than the heat treatment temperature, the RLM1M2 alloy is melted during the heat treatment, and the reduced RH is R-T-B It becomes easy to diffuse inside the sintered magnet. Therefore, before the RLM1M2 alloy powder and the RH carbonate powder are present on the surface of the R-T-B type sintered magnet, the surface of the R-T-B type sintered magnet is subjected to special washing such as pickling. It is not necessary to perform a cleaning process. Of course, it does not exclude performing such a cleaning process. Further, even if the surface of the RLM1M2 alloy powder particles is somewhat oxidized, the effect of reducing the RH carbonate is hardly affected.
粉末状態にあるＲＬＭ１Ｍ２合金およびＲＨ炭酸塩のＲ−Ｔ−Ｂ系焼結磁石の表面における存在比率（熱処理前）は、質量比率でＲＬＭ１Ｍ２合金：ＲＨ炭酸塩＝４０：６０〜９６：４であることが好ましく、存在比率はＲＬＭ１Ｍ２合金：ＲＨ炭酸塩＝６０：４０〜９０：１０であることがより好ましい。本開示の製造方法は、ＲＬＭ１Ｍ２合金およびＲＨ炭酸塩の粉末以外の粉末（第三の粉末）がＲ−Ｔ−Ｂ系焼結磁石の表面に存在することを必ずしも排除しないが、第三の粉末がＲＨ炭酸塩中のＲＨをＲ−Ｔ−Ｂ系焼結磁石の内部に拡散することを阻害しないように留意する必要がある。Ｒ−Ｔ−Ｂ系焼結磁石の表面に存在する粉末の全体に占める「ＲＬＭ１Ｍ２合金およびＲＨ炭酸塩」の粉末の質量比率は、７０％以上であることが望ましい。 The abundance ratio (before heat treatment) of the RLM1M2 alloy and RH carbonate in the powder state on the surface of the R-T-B system sintered magnet is RLM1M2 alloy: RH carbonate = 40: 60 to 96: 4 in mass ratio. It is preferable that the abundance ratio is RLM1M2 alloy: RH carbonate = 60: 40 to 90:10. Although the manufacturing method of the present disclosure does not necessarily exclude the presence of powders (third powder) other than RLM1M2 alloy and RH carbonate powder on the surface of the R-T-B sintered magnet, However, it is necessary to take care not to inhibit diffusion of RH in the RH carbonate into the inside of the R-T-B system sintered magnet. The mass ratio of the “RLM1M2 alloy and RH carbonate” powder in the entire powder existing on the surface of the RTB-based sintered magnet is desirably 70% or more.
本開示の製造方法によれば、少ない量のＲＨで、効率的にＲ−Ｔ−Ｂ系焼結磁石のＨcJを向上させることが可能である。Ｒ−Ｔ−Ｂ系焼結磁石の表面に存在させる粉末中のＲＨ元素の量は、Ｒ−Ｔ−Ｂ系焼結磁石に対して０．２〜１．５質量％であることが好ましい。 According to the manufacturing method of the present disclosure, it is possible to efficiently improve the H cJ of the RTB -based sintered magnet with a small amount of RH. The amount of RH element in the powder present on the surface of the RTB-based sintered magnet is preferably 0.2 to 1.5 mass% with respect to the RTB-based sintered magnet.
なお、ＲＨ炭酸塩の粉末に含有される重希土類元素ＲＨの質量比率は、一般に、ＲＨ酸化物またはＲＨフッ化物の粉末に含有される重希土類元素ＲＨの質量比率よりも低い。このため、同一量の重希土類元素ＲＨをＲ−Ｔ−Ｂ系焼結磁石内に拡散させるためには、ＲＨ酸化物またはＲＨフッ化物の粉末よりも多くＲＨ炭酸塩粉末を使用する必要がある。また、ＲＨ拡散源としてＲＨ炭酸塩を用いると、ＲＨ酸化物またはＲＨフッ化物を使用する場合に比べると、相対的に多くの拡散助剤を用いることが好ましいこともわかった。このため、ＲＨ拡散源としてＲＨ炭酸塩を使用する本開示の実施形態によれば、ＲＨ酸化物またはＲＨフッ化物を使用する場合よりも相対的に厚く粉末塗布層を形成することができる。このことは、粉末塗布層の厚さを調整する上で利点をもたらす。 The mass ratio of the heavy rare earth element RH contained in the RH carbonate powder is generally lower than the mass ratio of the heavy rare earth element RH contained in the RH oxide or RH fluoride powder. For this reason, in order to diffuse the same amount of heavy rare earth element RH into the RTB-based sintered magnet, it is necessary to use more RH carbonate powder than RH oxide or RH fluoride powder. . It has also been found that when RH carbonate is used as the RH diffusion source, it is preferable to use a relatively large amount of diffusion aid as compared to the case of using RH oxide or RH fluoride. For this reason, according to the embodiment of the present disclosure using RH carbonate as the RH diffusion source, the powder coating layer can be formed relatively thicker than in the case of using RH oxide or RH fluoride. This provides an advantage in adjusting the thickness of the powder coating layer.
［拡散熱処理］
熱処理温度はＲ−Ｔ−Ｂ系焼結磁石の焼結温度以下（具体的には例えば１０００℃以下）であり、かつ、ＲＬＭ１Ｍ２合金の粉末の融点よりも高い温度であるが、具体的には、５００℃以上が好ましい。熱処理時間は例えば１０分〜７２時間である。また前記熱処理の後必要に応じてさらに４００〜７００℃で１０分〜７２時間の熱処理を行ってもよい。
[Diffusion heat treatment]
The heat treatment temperature is equal to or lower than the sintering temperature of the RTB-based sintered magnet (specifically, for example, 1000 ° C. or lower) and higher than the melting point of the powder of the RLM1M2 alloy. 500 ° C. or higher is preferable. The heat treatment time is, for example, 10 minutes to 72 hours. Moreover, you may perform the heat processing for 10 minutes-72 hours at 400-700 degreeC further as needed after the said heat processing.
まず、公知の方法で、組成比Ｎｄ＝１３．４、Ｂ＝５．８、Ａｌ＝０．５、Ｃｕ＝０．１、Ｃｏ＝１．１、残部＝Ｆｅ（原子％）のＲ−Ｔ−Ｂ系焼結磁石を作製した。これを機械加工することにより、６．５ｍｍ×７．４ｍｍ×７．４ｍｍのＲ−Ｔ−Ｂ系焼結磁石母材を得た。得られたＲ−Ｔ−Ｂ系焼結磁石母材の磁気特性をＢ−Ｈトレーサーによって測定したところ、ＨcJは１０３５ｋＡ／ｍ、Ｂrは１．４５Ｔであった。なお、後述の通り、熱処理後のＲ−Ｔ−Ｂ系焼結磁石の磁気特性は、Ｒ−Ｔ−Ｂ系焼結磁石の表面を機械加工によって除去してから測定するので、Ｒ−Ｔ−Ｂ系焼結磁石母材もそれに合わせて、表面をさらに機械加工によって除去し、大きさ６．３ｍｍ×７．０ｍｍ×７．０ｍｍとしてから測定した。拡散剤として炭酸Ｔｂを用意した。具体的には、リサイクル工程において、Ｔｂを含有するＲ−Ｔ−Ｂ系磁石やＲＨ拡散源をＴと分離して得たＴｂ酸化物から得られる炭酸Ｔｂを想定し、Ｔｂ4Ｏ7試薬から模擬的に作製した。１０ｖｏｌ％塩酸にＴｂ4Ｏ7試薬を添加して６０℃で溶解後濾過した。こうして得た濾液に炭酸ナトリウムを添加し、６０℃で２時間放置した後、濾過して沈殿物を得た。この沈殿物を６０℃で６時間真空乾燥して炭酸Ｔｂ粉末を得た。炭酸Ｔｂ粉末の粒度は数μｍであった。また、得られた炭酸ＴｂをＩＣＰ分析により分析したところ、Ｔｂの含有率は５８．３ｍａｓｓ％であった。次に組成がＮｄ70Ｃｕ30（原子％）の拡散助剤を用意した（融点５２０℃：Ｎｄ−Ｃｕの二元系状態図で示される値）。拡散助剤は遠心アトマイズ法で作製し、粒度１０６μｍ以下とした。得られた拡散剤の粉末と拡散助剤の粉末を表１に示す混合比でポリビニルアルコールおよび純水と混合してスラリーを得た。このスラリーを、Ｒ−Ｔ−Ｂ系焼結磁石母材の７．４ｍｍ×７．４ｍｍの１面に、ＲＨ量がＲ−Ｔ−Ｂ系焼結磁石母材に対する質量比で０．２５％となるように塗布した。なお、本実施例は前記スラリーをＲ−Ｔ−Ｂ系焼結磁石母材の１つの拡散面のみに塗布してＨcJの向上効果を確認した実験である。実際には、１面でもよいし、２面〜全面の複数面でもよい。このＲ−Ｔ−Ｂ系焼結磁石母材を処理容器に収容して蓋をした。（この蓋は容器内外のガスの出入りを妨げるものではない。）これを熱処理炉に収容し、１００ＰａのＡｒ雰囲気中、９００℃で１０時間の熱処理を行った。熱処理は、室温から真空排気しながら昇温し、雰囲気圧力および温度が上記条件に達してから上記条件で行った。その後いったん室温まで降温してからＲ−Ｔ−Ｂ系焼結磁石を回収した。回収したＲ−Ｔ−Ｂ系焼結磁石を処理容器に戻して再び熱処理炉に収容し、１０Ｐａ以下の真空中、４９０℃で３時間の熱処理を行った。この熱処理も室温から真空排気しながら昇温し、雰囲気圧力および温度が上記条件に達してから上記条件で行った。その後いったん室温まで降温してからＲ−Ｔ−Ｂ系焼結磁石を回収した。 First, by a known method, the composition ratio Nd = 13.4, B = 5.8, Al = 0.5, Cu = 0.1, Co = 1.1, and the balance = Fe (atomic%) RT -B system sintered magnet was produced. By machining this, an RTB-based sintered magnet base material of 6.5 mm × 7.4 mm × 7.4 mm was obtained. Magnetic properties of the obtained R-T-B based sintered magnet base material where a measured by B-H tracer, H cJ is 1035kA / m, B r was 1.45 T. As will be described later, the magnetic properties of the RTB-based sintered magnet after heat treatment are measured after removing the surface of the RTB-based sintered magnet by machining. In accordance with the B-based sintered magnet base material, the surface was further removed by machining, and the size was measured after measuring 6.3 mm × 7.0 mm × 7.0 mm. Carbonic acid Tb was prepared as a diffusing agent. Specifically, Tb carbonate obtained from Tb oxide obtained by separating Tb-containing R-T-B magnet and RH diffusion source from T in the recycling process is assumed, and from Tb 4 O 7 reagent Simulated. Tb 4 O 7 reagent was added to 10 vol% hydrochloric acid and dissolved at 60 ° C., followed by filtration. Sodium carbonate was added to the filtrate thus obtained and allowed to stand at 60 ° C. for 2 hours, followed by filtration to obtain a precipitate. This precipitate was vacuum-dried at 60 ° C. for 6 hours to obtain Tb carbonate powder. The particle size of the Tb carbonate powder was several μm. Moreover, when the obtained carbonic acid Tb was analyzed by ICP analysis, the content rate of Tb was 58.3 mass%. Next, a diffusion aid having a composition of Nd 70 Cu 30 (atomic%) was prepared (melting point 520 ° C .: value shown in Nd—Cu binary phase diagram). The diffusion aid was prepared by a centrifugal atomization method and had a particle size of 106 μm or less. The obtained diffusion agent powder and diffusion aid powder were mixed with polyvinyl alcohol and pure water at a mixing ratio shown in Table 1 to obtain a slurry. This slurry is placed on one surface of a 7.4 mm × 7.4 mm R-T-B system sintered magnet base material, and the amount of RH is 0.25% by mass ratio to the R-T-B system sintered magnet base material. It applied so that it might become. In addition, a present Example is the experiment which apply | coated the said slurry only to one diffusion surface of a RTB system sintered magnet base material, and confirmed the improvement effect of HcJ . Actually, it may be one surface or a plurality of surfaces from the second surface to the entire surface. The RTB-based sintered magnet base material was accommodated in a processing container and covered. (This lid does not hinder the entry and exit of the gas inside and outside the container.) This was accommodated in a heat treatment furnace and subjected to heat treatment at 900 ° C. for 10 hours in an Ar atmosphere of 100 Pa. The heat treatment was carried out under the above conditions after the temperature was raised while evacuating from room temperature and the atmospheric pressure and temperature reached the above conditions. Thereafter, the temperature was lowered to room temperature, and then the R-T-B sintered magnet was collected. The recovered RTB-based sintered magnet was returned to the processing vessel and accommodated again in a heat treatment furnace, and heat treatment was performed at 490 ° C. for 3 hours in a vacuum of 10 Pa or less. This heat treatment was also performed under the above conditions after the temperature was raised while evacuating from room temperature and the atmospheric pressure and temperature reached the above conditions. Thereafter, the temperature was lowered to room temperature, and then the R-T-B sintered magnet was collected.
得られたＲ−Ｔ−Ｂ系焼結磁石の表面を機械加工にて除去し、６．３ｍｍ×７．０ｍｍ×７．０ｍｍのサンプル１〜４を得た。得られたサンプル１〜４の磁気特性をＢ−Ｈトレーサーによって測定し、ＨcJの変化量を求めた。結果を表１に示す。 The surface of the obtained RTB-based sintered magnet was removed by machining to obtain Samples 1 to 4 of 6.3 mm × 7.0 mm × 7.0 mm. The magnetic properties of the obtained samples 1 to 4 were measured with a BH tracer, and the amount of change in H cJ was determined. The results are shown in Table 1.
表１からわかるように、本開示の製造方法によるＲ−Ｔ−Ｂ系焼結磁石はＢrが低下することなくＨcJが大きく向上している。すなわち、ＲＬＭ１Ｍ２合金とＲＨ炭酸塩を混合して使用すれば、ＲＬＭ１Ｍ２合金がＲＨ炭酸塩を効率よく還元し、十分に還元されたＲＨがＲ−Ｔ−Ｂ系焼結磁石母材中に拡散することにより、少ないＲＨ量でＨcJを大きく向上させることができたことがわかった。 As can be seen from Table 1, R-T-B based sintered magnet according to the manufacturing method of the present disclosure H cJ is greatly improved without the B r drops. That is, if the RLM1M2 alloy and the RH carbonate are mixed and used, the RLM1M2 alloy efficiently reduces the RH carbonate, and the fully reduced RH diffuses into the RTB-based sintered magnet base material. Thus , it was found that HcJ could be greatly improved with a small amount of RH.
本開示の製造方法は、希少資源を効率的に利用して、高温下でも高いＨcJを維持することができるＲ−Ｔ−Ｂ系焼結磁石を製造できるため、当該製造方法によって得られる磁石を電気自動車（ＥＶ、ＨＶ、ＰＨＶなど）のモータなどに好適に用いることが可能になる。 Since the manufacturing method of the present disclosure can manufacture an RTB -based sintered magnet capable of maintaining high H cJ even at high temperatures by efficiently using rare resources, a magnet obtained by the manufacturing method Can be suitably used for a motor of an electric vehicle (EV, HV, PHV, etc.).
Claims (5)
前記Ｒ−Ｔ−Ｂ系焼結磁石の表面にＲＬＭ１Ｍ２合金（ＲＬは、Ｎｄ、Ｐｒから選ばれる１種以上、Ｍ１、Ｍ２はＣｕ、Ｆｅ、Ｇａ、Ｃｏ、Ｎｉ、Ａｌから選ばれる１種以上、Ｍ１＝Ｍ２でもよい）の粉末と、ＲＨ炭酸塩（ＲＨはＤｙおよび／またはＴｂ）の粉末とを存在させた状態において、前記Ｒ−Ｔ−Ｂ系焼結磁石の焼結温度以下で熱処理を行う工程と、
を含むＲ−Ｔ−Ｂ系焼結磁石の製造方法。 A step of preparing an R-T-B sintered magnet;
RLM1M2 alloy (RL is one or more selected from Nd and Pr, M1 and M2 are one or more selected from Cu, Fe, Ga, Co, Ni, and Al on the surface of the RTB-based sintered magnet. , M1 = M2) and RH carbonate powder (RH is Dy and / or Tb) in the presence of heat treatment at a temperature lower than the sintering temperature of the RTB-based sintered magnet. A process of performing
The manufacturing method of the RTB type | system | group sintered magnet containing this.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111243807A (en) * | 2020-02-26 | 2020-06-05 | 厦门钨业股份有限公司 | Neodymium-iron-boron magnet material, raw material composition, preparation method and application |
| CN111261352A (en) * | 2018-12-03 | 2020-06-09 | Tdk株式会社 | Method for manufacturing R-T-B permanent magnet |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111261352A (en) * | 2018-12-03 | 2020-06-09 | Tdk株式会社 | Method for manufacturing R-T-B permanent magnet |
| CN111243807A (en) * | 2020-02-26 | 2020-06-05 | 厦门钨业股份有限公司 | Neodymium-iron-boron magnet material, raw material composition, preparation method and application |
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