JP2013197240A - Neodymium-iron-boron-based rare earth sintered magnet, and method of manufacturing the same - Google Patents
Neodymium-iron-boron-based rare earth sintered magnet, and method of manufacturing the same Download PDFInfo
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Abstract
Description
本発明は、超高純度化技術を応用した磁性材料に関し、従来に比べて磁気特性を格段に向上させた高純度Ｎｄ−Ｆｅ−Ｂ系希土類永久磁石及びその製造方法に関する。 The present invention relates to a magnetic material to which an ultra-high purity technology is applied, and relates to a high-purity Nd—Fe—B rare earth permanent magnet whose magnetic characteristics are remarkably improved as compared with the prior art and a method for manufacturing the same.
近年、永久磁石は飛躍的な進歩に端を発して様々な分野へ応用され、その性能の向上と新しい機器の開発が日々刻々となされている。特に、省エネや環境対策の観点から、ＩＴ、自動車、家電、ＦＡ分野などへの普及が急激に伸びている。
永久磁石の用途として、パソコンでは、ハードディスクドライブ用ボイスコイルモーターやＤＶＤ／ＣＤの光ピックアップ用部品、携帯電話では、マイクロスピーカーやバイブレーションモーター、家電や産業機器関連では、サーボモーターやリニアモーターなどの各種モーターがある。また、ＨＥＶなどの電気自動車には、１台当たり１００個以上の永久磁石が使用されている。
In recent years, permanent magnets have been applied to various fields as a result of dramatic progress, and improvements in their performance and development of new devices have been made every day. In particular, from the viewpoints of energy saving and environmental measures, the spread to IT, automobiles, home appliances, FA fields, etc. is growing rapidly.
Permanent magnet applications include voice coil motors for hard disk drives and optical pickup parts for DVD / CD for personal computers, microspeakers and vibration motors for mobile phones, and servo motors and linear motors for home appliances and industrial equipment. There is a motor. Moreover, 100 or more permanent magnets are used for one electric vehicle such as HEV.
永久磁石として、アルニコ（Ａｌｎｉｃｏ）磁石、フェライト（Ｆｅｅｒｒｉｔｅ）磁石、サマコバ（ＳｍＣｏ）磁石、ネオジム（ＮｄＦｅＢ）磁石などが知られている。近年では、特にネオジム磁石の研究開発が活発であり、高性能化に向けて様々な取り組みが行われている。ネオジム磁石は通常、強磁性のＮｄ２Ｆｅ１４Ｂ４金属間化合物（主相）、常磁性のＢリッチ相、非磁性のＮｄリッチ相、さらに不純物としての酸化物などから構成されている。これにさらに種々の元素を添加するなどして、磁気特性を改善させる取り組みが行われている。
例えば、特許文献１には、Ｒ−Ｆｅ−Ｂ系希土類永久磁石（Ｒは、Ｎｄ、Ｐｒ、Ｄｙ、Ｔｂ、Ｈｏのうちの１種又は２種以上）に、Ｃｏ、Ａｌ、Ｃｕ及びＴｉを同時に添加することにより、磁気特性を著しく改良することが開示されており、また、特許文献２には、組成を調整しながらＧａを添加することで、最大エネルギー積（ＢＨ）ｍａｘを４２ＭＯｅ以上とすることが開示されている。
As a permanent magnet, an Alnico magnet, a ferrite magnet, a Samaco magnet, a neodymium (NdFeB) magnet, and the like are known. In recent years, research and development of neodymium magnets has been particularly active, and various efforts have been made toward higher performance. A neodymium magnet is generally composed of a ferromagnetic Nd 2 Fe 14 B 4 intermetallic compound (main phase), a paramagnetic B-rich phase, a nonmagnetic Nd-rich phase, and an oxide as an impurity. Further efforts are being made to improve magnetic properties by adding various elements.
For example, Patent Document 1 discloses that an R—Fe—B rare earth permanent magnet (R is one or more of Nd, Pr, Dy, Tb, and Ho) and Co, Al, Cu, and Ti. It is disclosed that the magnetic properties are remarkably improved by the simultaneous addition, and Patent Document 2 discloses that the maximum energy product (BH) max is 42 MOe or more by adding Ga while adjusting the composition. Is disclosed.
磁気特性を向上させるために、その他にも、磁気特性を低下させる要因である不純物の酸素を適当な量導入する方法（特許文献３）、適量添加したフッ素が磁石の粒界部分に偏在することで主相結晶粒の成長を抑えて保磁力を上昇させる方法（特許文献４）、磁気特性を低下させるＢリッチ相やＲリッチ相を低減し、主相のＲ２Ｆｅ１４Ｂ相を増加させることで磁石の性能を向上させる方法（特許文献５）などが、知られている。 In order to improve the magnetic characteristics, there are other methods of introducing an appropriate amount of impurity oxygen (a patent document 3), which is a factor that deteriorates the magnetic characteristics, and that an appropriate amount of added fluorine is unevenly distributed in the grain boundary portion of the magnet. The method of increasing the coercive force by suppressing the growth of the main phase crystal grains (Patent Document 4), reducing the B-rich phase and R-rich phase that lower the magnetic properties, and increasing the R 2 Fe 14 B phase as the main phase A method for improving the performance of the magnet (Patent Document 5) is known.
このように、磁気特性を向上させるために、新たな種類の成分元素（希土類元素、遷移金属元素、不純物元素など）を添加したり、Ｒ−Ｆｅ−Ｂ系希土類焼結磁石の組成を調整したり、その他にも結晶配向を調整するなどして、磁気特性を改善する試みが行われているが、このような方法はいずれも、製造工程を煩雑とするため、安定的な量産に適しているとは言えない。 Thus, in order to improve the magnetic properties, new types of component elements (rare earth elements, transition metal elements, impurity elements, etc.) are added, and the composition of the R—Fe—B rare earth sintered magnet is adjusted. In addition, attempts have been made to improve the magnetic properties by adjusting the crystal orientation, etc., but all of these methods make the manufacturing process complicated and suitable for stable mass production. I can't say.
本発明は、高純度Ｎｄ−Ｆｅ−Ｂ系希土類永久磁石において、特に、硫黄及びリンの含有量を低減することにより、磁気材料特有の弱点である耐熱性、耐食性を著しく改善することができ、さらには、磁気特性を格段に向上させた高性能のＮｄ−Ｆｅ−Ｂ系希土類永久磁石を提供することを課題とする。 The present invention is a high-purity Nd-Fe-B-based rare earth permanent magnet, and in particular, by reducing the content of sulfur and phosphorus, it is possible to remarkably improve heat resistance and corrosion resistance, which are weak points peculiar to magnetic materials, It is another object of the present invention to provide a high-performance Nd—Fe—B rare earth permanent magnet with significantly improved magnetic properties.
上記の課題を解決するために、本発明者らは鋭意研究を行った結果、従来では、使用原料中に含まれ、あるいは、製造工程中で混入する不可避的不純物であるとして特に問題視されていなかった硫黄、リンを低減させることで、従来のＮｄ−Ｆｅ−Ｂ系希土類永久磁石に比べて、耐熱性や耐食性を著しく改善でき、さらに、磁気特性を格段に向上できることを見出した。 In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, conventionally, they have been regarded as particularly problematic as being unavoidable impurities contained in the raw materials used or mixed in the manufacturing process. It has been found that heat and corrosion resistance can be remarkably improved as compared with conventional Nd—Fe—B rare earth permanent magnets, and magnetic properties can be remarkably improved by reducing the amount of sulfur and phosphorus that are not present.
このような知見に基づき、本発明は、
１）ガス成分を除く純度が９９．９ｗｔ％以上であって、硫黄、リンの含有量がそれぞれ３０ｗｔｐｐｍ以下であることを特徴とするＮｄ−Ｆｅ−Ｂ系希土類永久磁石、
２）酸素含有量が５００ｗｔｐｐｍ以下であることを特徴とする前記１）記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石、
３）炭素含有量が１００ｗｔｐｐｍ以下であることを特徴とする前記１）又は２）に記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石、
４）ガス成分を除く純度が９９．９９ｗｔ％以上であることを特徴とする前記１）〜３）のいずれか一に記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石、
５）ガス成分を除く純度が９９．９９９ｗｔ％以上であることを特徴とする前記１）〜３）のいずれか一に記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石、
６）純度が９９ｗｔ％である同一組成のＮｄ−Ｆｅ−Ｂ系希土類永久磁石に比べて、最大エネルギー積（ＢＨ）ｍａｘの増加率が５％以上であることを特徴とする前記１）〜５）のいずれか一に記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石、
７）純度が９９ｗｔ％である同一組成のＮｄ−Ｆｅ−Ｂ系希土類永久磁石に比べて、耐熱温度の上昇率が１０％以上であることを特徴とする前記１）〜６）のいずれか一に記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石、を提供する。
Based on such knowledge, the present invention
1) Nd—Fe—B rare earth permanent magnets having a purity excluding gas components of 99.9 wt% or more and sulfur and phosphorus contents of 30 wtppm or less,
2) The Nd—Fe—B rare earth permanent magnet according to 1) above, wherein the oxygen content is 500 wtppm or less,
3) The Nd-Fe-B rare earth permanent magnet according to 1) or 2) above, wherein the carbon content is 100 wtppm or less,
4) The Nd—Fe—B rare earth permanent magnet according to any one of 1) to 3) above, wherein the purity excluding gas components is 99.99 wt% or more,
5) The Nd—Fe—B rare earth permanent magnet according to any one of 1) to 3) above, wherein the purity excluding gas components is 99.999 wt% or more,
6) The above-mentioned 1) to 5), wherein the increase rate of the maximum energy product (BH) max is 5% or more as compared with an Nd—Fe—B rare earth permanent magnet having the same composition and a purity of 99 wt%. Nd—Fe—B based rare earth permanent magnet according to any one of
7) The increase rate of the heat-resistant temperature is 10% or more as compared with the Nd—Fe—B rare earth permanent magnet of the same composition having a purity of 99 wt%. The Nd—Fe—B rare earth permanent magnet described in 1. is provided.
また、本発明は、
８）Ｎｄ原料、Ｂ原料をそれぞれ酸化物からのＣａ還元により純度９９．９％以上、硫黄、リン含有量をそれぞれ３０ｗｔｐｐｍ以下とし、Ｆｅ原料を水溶液電解により純度９９．９％以上、硫黄、リン含有量をそれぞれ３０ｗｔｐｐｍ以下とし、次に、これらを配合した配合物を真空溶解してインゴットとし、このインゴットを粉砕して粉末化した後、これをプレスにより成形し、その後、この成形体を焼結、熱処理を行った後、この焼結体を表面加工することを特徴とするＮｄ−Ｆｅ−Ｂ系希土類永久磁石の製造方法、
９）Ｎｄ原料、Ｂ原料をそれぞれ酸化物からのＣａ還元と溶融塩電解により純度９９．９９％以上、硫黄、リン含有量をそれぞれ１０ｗｔｐｐｍ以下とし、Ｆｅ原料を複数回の水溶液電解により純度９９．９９％以上、硫黄、リン含有量をそれぞれ１０ｗｔｐｐｍ以下とすることを特徴とする前記８）記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石の製造方法、
１０）Ｎｄ原料、Ｂ原料をそれぞれ酸化物からのＣａ還元と複数回の溶融塩電解により純度９９．９９９％以上、硫黄、リン含有量をそれぞれ１０ｗｔｐｐｍ以下とし、Ｆｅ原料を溶媒抽出と複数回の水溶液電解により純度９９．９９９％以上、硫黄、リン含有量をそれぞれ１０ｗｔｐｐｍ以下とすることを特徴とする前記９）記載のＮｄ−Ｆｅ−Ｂ系希土類永久磁石の製造方法、
The present invention also provides:
8) Purity of Nd raw material and B raw material is reduced to 99.9% or more by reduction of Ca from oxide, sulfur and phosphorus contents are each 30 wtppm or less, and Fe raw material is purified by aqueous solution electrolysis to purity of 99.9% and sulfur, phosphorus Each content is set to 30 wtppm or less, and then a compounded mixture thereof is vacuum-dissolved to form an ingot. After the ingot is pulverized and pulverized, it is molded by pressing, and then the molded body is baked. A method for producing a Nd-Fe-B rare earth permanent magnet, characterized in that after sintering and heat treatment, the sintered body is subjected to surface processing.
9) Purity of Nd raw material and B raw material is 99.99% or more by Ca reduction from molten oxide and molten salt electrolysis, sulfur and phosphorus contents are each 10 wtppm or less, and Fe raw material is 99. 99% or more, sulfur and phosphorus contents are each 10 wtppm or less, the method for producing an Nd-Fe-B rare earth permanent magnet according to 8) above,
10) Nd raw material and B raw material were each reduced by Ca reduction from oxide and multiple times of molten salt electrolysis to a purity of 99.999% or more, sulfur and phosphorus contents were each 10 wtppm or less, Fe raw material was extracted by solvent extraction and multiple times 9) The method for producing an Nd—Fe—B rare earth permanent magnet according to 9) above, wherein the purity is 99.999% or more by aqueous solution electrolysis, and the sulfur and phosphorus contents are each 10 wtppm or less,
本発明の高純度Ｎｄ−Ｆｅ−Ｂ系希土類永久磁石は、特に、硫黄及びリンの含有量を低減したことにより、磁性材料特有の弱点である耐熱性、耐食性を著しく改善でき、さらには、製造プロセスを煩雑にすることなく、磁気特性を格段に向上させることができる優れた効果を有する。 The high-purity Nd—Fe—B rare earth permanent magnet of the present invention can remarkably improve heat resistance and corrosion resistance, which are weak points peculiar to magnetic materials, by reducing the content of sulfur and phosphorus. Without complicating the process, the magnetic properties can be improved significantly.
本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、硫黄、リンの含有量がそれぞれ３０ｗｔｐｐｍ以下である。硫黄、リンの含有量が３０ｗｔｐｐｍ以下とすることで、耐食性及び耐熱性を著しく向上することができる。Ｎｄ−Ｆｅ−Ｂ系希土類永久磁石は、Ｆｅを多く含有するため錆び易く、また、高温領域で使用すると減磁することが知られている。硫黄、リンの含有量がそれぞれ３０ｗｔｐｐｍ以下とすることにより、これらの問題を大幅に低減することができる。 The Nd—Fe—B rare earth permanent magnet of the present invention has sulfur and phosphorus contents of 30 wtppm or less, respectively. When the content of sulfur and phosphorus is 30 wtppm or less, the corrosion resistance and heat resistance can be remarkably improved. Nd-Fe-B rare earth permanent magnets are known to rust easily because they contain a large amount of Fe, and to be demagnetized when used in a high temperature region. By setting the sulfur and phosphorus contents to 30 wtppm or less, these problems can be greatly reduced.
また、本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、ガス成分を除く純度が９９．９ｗｔ％以上、好ましくは、純度９９．９９ｗｔ％以上、さらに好ましくは、９９．９９９ｗｔ％以上である。
本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、高純度のＮｄ、Ｆｅ、Ｂを原料として使用することで、特に煩雑なプロセスを経ることなく、磁気特性を格段に向上させるものである。したがって、従来のように希土類永久磁石の成分組成を調整することにより、磁気特性の向上させるものではないので、永久磁石として通常の磁気特性を有するものであれば、成分組成に特に制限はない。
The Nd—Fe—B rare earth permanent magnet of the present invention has a purity excluding gas components of 99.9 wt% or more, preferably a purity of 99.99 wt% or more, more preferably 99.999 wt% or more.
The Nd—Fe—B-based rare earth permanent magnet of the present invention uses a high purity Nd, Fe, B as a raw material, so that the magnetic properties are remarkably improved without a particularly complicated process. Therefore, since the magnetic properties are not improved by adjusting the component composition of the rare earth permanent magnet as in the prior art, the component composition is not particularly limited as long as the permanent magnet has normal magnetic properties.
本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、Ｎｄ、Ｆｅ、Ｂが典型的な成分であるが、磁気特性の向上や耐食性などの改善のために、添加成分として、Ｄｙ、Ｐｒ、Ｔｂ、Ｈｏなどの希土類元素や、Ｃｏ、Ｎｉ、Ａｌなどの遷移金属元素を含んでもよい。但し、これらの添加成分は、本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石の純度から除かれる、すなわち、不純物にはカウントしないことは言うまでもない。 In the Nd—Fe—B rare earth permanent magnet of the present invention, Nd, Fe, and B are typical components. However, in order to improve magnetic properties and corrosion resistance, Dy, Pr, and Tb are added as additive components. , Ho and other rare earth elements, and Co, Ni, Al and other transition metal elements. However, it goes without saying that these additive components are excluded from the purity of the Nd—Fe—B rare earth permanent magnet of the present invention, that is, not counted as impurities.
本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、これまで知られている、同一の組成の希土類永久磁石と比べて優れた磁気特性を有する。希土類永久磁石として、３１Ｎｄ−６８Ｆｅ−１Ｂ（用途：ＭＲＩ）、２６Ｎｄ−５Ｄｙ−６８Ｆｅ−１Ｂ（用途：ＯＡ機器サーボモーター）、２１Ｎｄ−１０Ｄｙ−６８Ｆｅ−１Ｂ（用途：ハイブリッドカー用モーター）などが知られているが、これらの全てにおいて、成分元素を高純度化することにより、従来のものよりも磁気特性を向上させることができる。 The Nd-Fe-B rare earth permanent magnet of the present invention has excellent magnetic properties as compared with rare earth permanent magnets of the same composition known so far. Known rare earth permanent magnets include 31Nd-68Fe-1B (use: MRI), 26Nd-5Dy-68Fe-1B (use: OA equipment servo motor), 21Nd-10Dy-68Fe-1B (use: motor for hybrid cars), etc. However, in all of these, by increasing the purity of the component elements, the magnetic properties can be improved as compared with the conventional one.
本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、酸素含有量が５００ｗｔｐｐｍ以下である。また、炭素含有量が１００ｗｔｐｐｍ以下である。酸素含有量が５００ｗｔｐｐｍ以下、また、炭素含有量が１００ｗｔｐｐｍ以下とすることで、従来よりも優れた耐食性及び耐熱性が得られる。従来は、これらのガス成分は不可避的不純物として、通常混入する量であれば特に問題ないとされていたが、これらの含有量を本発明レベルまで極めて低減することにより、耐食性や耐熱性を大幅に向上することが本発明の最も重要な特徴である。 The Nd—Fe—B rare earth permanent magnet of the present invention has an oxygen content of 500 wtppm or less. The carbon content is 100 wtppm or less. By setting the oxygen content to 500 wtppm or less and the carbon content to 100 wtppm or less, corrosion resistance and heat resistance superior to conventional ones can be obtained. In the past, these gas components were unavoidable as impurities, so long as they were normally mixed, there was no particular problem, but by reducing these contents to the level of the present invention, corrosion resistance and heat resistance were greatly improved. This is the most important feature of the present invention.
本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、純度が９９ｗｔ％（２Ｎレベル）である同一組成の永久磁石に比べて、最大エネルギー積（ＢＨ）ｍａｘの増加率が５％以上であることが好ましい。より好ましくは１０％以上、さらに好ましくは２０％以上である。なお、最大エネルギー積（ＢＨ）ｍａｘは、残留磁束密度（Ｂ）と保磁力（Ｈ）との積である。
また、本発明の高純度ネオジム系希土類永久磁石は、純度が９９ｗｔ％（２Ｎレベル）である同一組成の永久磁石に比べて、耐熱温度の上昇率が１０％以上であることが好ましい。ネオジム系永久磁石は、用途によっては耐熱性が要求される。一般にジスプロシウムなどを添加することで、耐熱温度を上昇させることが行われているが、本発明ではこのような元素を添加することなしに、耐熱性を向上させることができるという優れた効果を有する。
The Nd—Fe—B rare earth permanent magnet of the present invention has an increase rate of the maximum energy product (BH) max of 5% or more as compared with a permanent magnet of the same composition having a purity of 99 wt% (2N level). Is preferred. More preferably, it is 10% or more, More preferably, it is 20% or more. The maximum energy product (BH) max is a product of the residual magnetic flux density (B) and the coercive force (H).
In addition, the high-purity neodymium-based rare earth permanent magnet of the present invention preferably has an increase rate of the heat-resistant temperature of 10% or more as compared with a permanent magnet having the same composition with a purity of 99 wt% (2N level). Neodymium permanent magnets are required to have heat resistance depending on the application. In general, dysprosium or the like is added to increase the heat resistance temperature, but the present invention has an excellent effect that heat resistance can be improved without adding such an element. .
また、本発明において、耐食性や脆性を低減するために、一般に希土類永久磁石をニッケルなどの金属でメッキすることが知られているが、本発明はこれらのメッキ処理を施す工程を省略することができる。一方、これらの技術を組み合わせることによって、耐食性や加工性などをさらに向上させることができる。 In the present invention, it is generally known that rare earth permanent magnets are plated with a metal such as nickel in order to reduce corrosion resistance and brittleness. However, the present invention omits the step of performing these plating treatments. it can. On the other hand, by combining these techniques, the corrosion resistance and workability can be further improved.
以下に製造方法の詳細を説明するが、この製造方法は、代表的かつ好適な例を示すものである。すなわち、本発明は以下の製造方法に制限するものではなく、他の製造方法であっても、本願発明の目的と条件を達成できるものであれば、それらの製造法を任意に採用できることは容易に理解される。 Details of the production method will be described below, but this production method shows a typical and preferred example. In other words, the present invention is not limited to the following production methods, and it is easy to adopt any other production method as long as the object and conditions of the present invention can be achieved. To be understood.
まず、市販のＮｄ原料（純度２Ｎレベル）、市販のＦｅ原料（純度２〜３Ｎレベル）、市販のＢ原料（純度２Ｎレベル）を用意する。また場合に応じて、添加成分としての、市販のＤｙ原料（純度２Ｎレベル）などを用意する。
次いで、Ｎｄ原料及びＢ原料を酸化物からのＣａ還元と溶融塩電解により、硫黄、リンの含有量を３０ｗｔｐｐｍ以下、酸素、炭素の含有量を１００ｗｔｐｐｍ以下、純度４Ｎ〜５ＮレベルのＮｄ、Ｂが得られる。また、Ｆｅ原料を溶媒抽出と１回又は２回以上の水溶液電解により、硫黄、リンの含有量を１０ｗｔｐｐｍ以下、酸素、炭素の含有量を１０ｗｔｐｐｍ以下、純度５Ｎ〜６ＮレベルのＦｅが得られる。
なお、含有量が少ない成分、例えば、Ｂについては高純度化せずそのまま使用することも可能である。
First, a commercially available Nd material (purity 2N level), a commercially available Fe material (purity 2 to 3N level), and a commercially available B material (purity 2N level) are prepared. Moreover, according to the case, the commercially available Dy raw material (purity 2N level) etc. as an additional component are prepared.
Next, Nd raw material and B raw material are subjected to Ca reduction from oxide and molten salt electrolysis. can get. Also, Fe extraction with solvent extraction and aqueous solution electrolysis once or twice or more can provide Fe of sulfur and phosphorus content of 10 wtppm or less, oxygen and carbon content of 10 wtppm or less, and purity levels of 5N to 6N.
In addition, about a component with little content, for example, B, it is also possible to use as it is, without refinement | purifying.
これらの高純度の原料を所望の組成になるように秤量する。このとき、組成は用途に応じて適宜決定することができる。一例として、Ｎｄ１５〜３５ｗｔ％、Ｄｙ０〜１０ｗｔ％、Ｂ０．５〜２ｗｔ％、Ｆｅ６０〜９０ｗｔ％となるように、原料を配合することができる。
次いで、これらの原料を高周波溶解炉にて、加熱溶解してインゴットを形成する。なお、加熱温度は１２５０℃程度とするのが好ましい。このインゴットも、硫黄、リンの含有量が１０ｗｔｐｐｍ以下、酸素、炭素の含有量が１００ｗｔｐｐｍ以下であった。
その後、このインゴットをジェットミル等の公知の手法を用いて、粉砕する。このとき、混合中の酸化の問題を考慮すると、不活性ガス雰囲気中あるいは真空中で混合することが好ましい。粉砕粉の平均粒径は３〜５μｍ程度とするのが好ましい。
These high purity raw materials are weighed so as to have a desired composition. At this time, a composition can be suitably determined according to a use. As an example, a raw material can be mix | blended so that it may become Nd15-35 wt%, Dy0-10 wt%, B0.5-2 wt%, Fe60-90 wt%.
Next, these raw materials are heated and melted in a high-frequency melting furnace to form an ingot. In addition, it is preferable that heating temperature shall be about 1250 degreeC. This ingot also had a sulfur and phosphorus content of 10 wtppm or less and an oxygen and carbon content of 100 wtppm or less.
Thereafter, the ingot is pulverized using a known method such as a jet mill. At this time, considering the problem of oxidation during mixing, it is preferable to mix in an inert gas atmosphere or in a vacuum. The average particle size of the pulverized powder is preferably about 3 to 5 μm.
次いで、合金化した粉砕粉を磁場プレス機によって成形する。このとき、磁場強度１５〜３０ＫＯｅ、成形密度４〜５ｇ／ｃｃとするのが好ましい。また、高性能の永久磁石の場合には、窒素雰囲気で成形することが好ましい。
次に、得られた成形体を焼結炉で焼結し、その後、この焼結体を熱処理炉で熱処理する。このとき、焼結炉の温度を１１００〜１１５０℃とし、また熱処理炉の温度を５００〜１０００℃とするのが好ましい。それぞれの炉内の雰囲気は、真空中で行うことが好ましい。なお、焼結と熱処理を同一の炉内にて行うことも可能である。
Next, the alloyed pulverized powder is formed by a magnetic field press. At this time, it is preferable that the magnetic field strength is 15 to 30 KOe and the molding density is 4 to 5 g / cc. Further, in the case of a high performance permanent magnet, it is preferable to mold in a nitrogen atmosphere.
Next, the obtained molded body is sintered in a sintering furnace, and then the sintered body is heat-treated in a heat treatment furnace. At this time, the temperature of the sintering furnace is preferably 1100 to 1150 ° C, and the temperature of the heat treatment furnace is preferably 500 to 1000 ° C. The atmosphere in each furnace is preferably performed in a vacuum. It is also possible to perform sintering and heat treatment in the same furnace.
次に、得られた焼結体をスライジングマシンなど公知の手法を用いて切断加工した後、表面や外周部分を研磨器や研削盤を用いて最終表面処理を行う。その後、必要に応じて、表面にニッケルや銅などによって金属メッキを行うことができる。メッキ方法は、公知の手法を用いることができる。めっき厚みは１０〜２０μｍとするのが好ましい。 Next, the obtained sintered body is cut using a known method such as a sizing machine, and then the surface or outer peripheral portion is subjected to final surface treatment using a polishing machine or a grinding machine. Thereafter, if necessary, the surface can be plated with nickel, copper, or the like. As the plating method, a known method can be used. The plating thickness is preferably 10 to 20 μm.
以上によって、ガス成分を除く純度が９９．９９ｗｔ％以上であって、硫黄、リンの含有量がそれぞれ１０ｗｔｐｐｍ以下であるＮｄ−Ｆｅ−Ｂ系希土類永久磁石を得ることができる。このような、高純度の希土類永久磁石は従来の、同一組成を有する希土類永久磁石に比べて、耐熱性、耐食性などを改善することができ、また、磁気特性を向上させることができる。
本発明の高純度希土類永久磁石は、Ｎｄ、Ｆｅ、Ｂを成分として含有する全ての永久磁石に適用できる。したがって、他の成分、含有量については、特に制限のないことは容易に理解できるであろう。つまり、既に公知の成分からなる希土類永久磁石に特に有用である。
As described above, an Nd—Fe—B rare earth permanent magnet having a purity excluding gas components of 99.99 wt% or more and sulfur and phosphorus contents of 10 wtppm or less can be obtained. Such a high-purity rare earth permanent magnet can improve heat resistance, corrosion resistance, and the like, and can improve magnetic properties as compared with a conventional rare earth permanent magnet having the same composition.
The high-purity rare earth permanent magnet of the present invention can be applied to all permanent magnets containing Nd, Fe, and B as components. Therefore, it can be easily understood that there are no particular restrictions on other components and contents. That is, it is particularly useful for rare earth permanent magnets made of already known components.
次に、本発明の実施例について説明する。なお、本実施例はあくまで一例であり、この例に制限されるものではない。すなわち、本発明の技術思想の範囲に含まれる実施例以外の態様あるいは変形を全て包含するものである。 Next, examples of the present invention will be described. In addition, a present Example is an example to the last, and is not restrict | limited to this example. That is, all the aspects or modifications other than the Example included in the scope of the technical idea of the present invention are included.
［組成：３１Ｎｄ−６８Ｆｅ−１Ｂ］
（参照例１）
市販の純度２Ｎレベルのネオジム原料を３１ｋｇ用意した。また、市販の純度３Ｎレベルの鉄を６８ｋｇ用意した。また、市販の純度２Ｎレベルのボロンを１ｋｇ用意した。
次に、上記の原料を高周波溶解炉において、加熱温度を１２５０℃程度にて、加熱溶解してインゴットを製造した。その後、製造したインゴットを、不活性ガスアルゴン雰囲気中、ジェットミルを用いて粉砕した。このとき、粉砕粉の平均粒径を４μｍ程度とした。
次に、このように合金化させた粉砕粉を、窒素雰囲気中、磁場強度２０ＫＯｅ、成形密度４.５ｇ／ｃｃとして、磁場プレス機を用いて成形した。その後、この成形体を焼結炉にて焼結した後、この焼結体を熱処理炉で熱処理した。このとき、焼結炉の温度を１１５０℃、熱処理炉の温度を７００℃とした。また、それぞれの炉内の雰囲気を真空とした。
このようにして製造した焼結体を、スライシングマシンを用いて切断加工し、その後、表面や外周部分を研磨器や研削盤を用いて最終表面処理を行った。なお、一般に、この後に酸化防止のためメッキ処理を施すことがあるが、今回は行わなかった。
その結果、参照例１で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、参照例１のネオジム系希土類永久磁石の純度は２Ｎ（９９ｗｔ％）レベルであり、Ｐの含有量は４５ｐｐｍ、Ｓの含有量は１２０ｐｐｍ、Ｏ含有量は９２０ｐｐｍ、Ｃ含有量は３２０ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが４６ＭＯｅであった。また、耐熱温度が１０５℃であり、耐熱性は後述する実施例１−３に比べて劣る結果をなった。なお、耐食性は、「ＪＩＳ Ｚ ２３７１（塩水噴霧試験方法）」を用い、各種試料の状態を観察して、比較評価した。
[Composition: 31Nd-68Fe-1B]
(Reference Example 1)
31 kg of a commercially available neodymium raw material with a purity level of 2N was prepared. Moreover, 68 kg of commercially available iron having a purity level of 3N was prepared. Further, 1 kg of commercially available boron having a purity level of 2N was prepared.
Next, the above raw material was heated and melted in a high-frequency melting furnace at a heating temperature of about 1250 ° C. to produce an ingot. Thereafter, the produced ingot was pulverized using a jet mill in an inert gas argon atmosphere. At this time, the average particle size of the pulverized powder was about 4 μm.
Next, the pulverized powder alloyed in this manner was molded using a magnetic field press in a nitrogen atmosphere at a magnetic field strength of 20 KOe and a molding density of 4.5 g / cc. Thereafter, the compact was sintered in a sintering furnace, and then the sintered body was heat-treated in a heat treatment furnace. At this time, the temperature of the sintering furnace was 1150 ° C., and the temperature of the heat treatment furnace was 700 ° C. Moreover, the atmosphere in each furnace was made into vacuum.
The sintered body thus produced was cut using a slicing machine, and then the final surface treatment was performed on the surface and the outer peripheral portion using a polishing machine and a grinding machine. In general, after this, plating treatment may be performed to prevent oxidation, but this time it was not performed.
As a result, Table 1 shows the purity, magnetic properties, and heat-resistant temperature of the neodymium-based rare earth permanent magnet produced in Reference Example 1. As shown in Table 1, the purity of the neodymium-based rare earth permanent magnet of Reference Example 1 is 2N (99 wt%) level, P content is 45 ppm, S content is 120 ppm, O content is 920 ppm, C content The amount was 320 ppm. At this time, the maximum energy product (BH) max was 46 MOe. Moreover, the heat resistant temperature was 105 ° C., and the heat resistance was inferior to that of Example 1-3 described later. Corrosion resistance was evaluated by using “JIS Z 2371 (salt spray test method)” and observing the state of various samples.
（実施例１）
純度２Ｎレベルのネオジム原料を、３Ｎレベルのネオジム酸化物を４Ｎレベルのカルシウムを用いて還元することにより純度３Ｎレベルとし、それを３１ｋｇ製造した。また、純度３Ｎレベルの鉄原料を、カソライトを塩酸系（アノライトは硫酸系）の水溶液にした隔膜電解により純度４Ｎレベルと、それを６８ｋｇ製造した。また、ボロン原料については、市販の純度２Ｎレベルを１ｋｇ用意した。その後の工程は、参照例１と同様の条件とした。
その結果、実施例１で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、実施例１のネオジム系希土類永久磁石の純度は３Ｎ（９９．９ｗｔ％）レベルであり、Ｐの含有量は３０ｐｐｍ、Ｓの含有量は３０ｐｐｍ、Ｏ含有量は５００ｐｐｍ、Ｃ含有量は１００ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが４９ＭＯｅであり、参照例１に比べて７％上昇していた。また、耐熱温度が１４０℃であり、参照例１に比べて３３％上昇していた。さらに、耐食性も参照例１に比べて良好な結果を示した。
Example 1
A 2N level neodymium raw material was reduced to 3N level by reducing 3N level neodymium oxide with 4N level calcium, and 31 kg of it was produced. Further, the iron raw material having a purity level of 3N was produced by membrane electrolysis in which catholyte was converted into a hydrochloric acid-based (an anolyte was sulfuric acid-based) aqueous solution to produce a 4N purity level of 68 kg. Moreover, about the boron raw material, 1 kg of commercially available purity 2N level was prepared. Subsequent steps were performed under the same conditions as in Reference Example 1.
As a result, Table 1 shows the purity, magnetic properties, and heat-resistant temperature of the neodymium-based rare earth permanent magnet produced in Example 1. As shown in Table 1, the purity of the neodymium rare earth permanent magnet of Example 1 is 3N (99.9 wt%) level, the P content is 30 ppm, the S content is 30 ppm, the O content is 500 ppm, The C content was 100 ppm. At this time, the maximum energy product (BH) max was 49 MOe, which was 7% higher than that of Reference Example 1. The heat-resistant temperature was 140 ° C., which was 33% higher than that of Reference Example 1. Further, the corrosion resistance was better than that of Reference Example 1.
（実施例２）
純度２Ｎレベルのネオジム原料を、３Ｎレベルのネオジム酸化物を４Ｎレベルのカルシウムを用いて還元及び溶融塩電解することにより純度４Ｎレベルとし、それを３１ｋｇ製造した。また、純度３Ｎレベルの鉄原料を、カソライトを塩酸系（アノライトは硫酸系）の水溶液にした隔膜電解を２回行うことにより純度４Ｎレベルとし、それを６８ｋｇ製造した。また、ボロン原料については、市販の純度２Ｎレベルを１ｋｇ用意した。その後の工程は、参照例１と同様の条件とした。
その結果、実施例２で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、実施例２のネオジム系希土類永久磁石の純度は４Ｎ（９９．９９ｗｔ％）レベルであり、Ｐの含有量は１０ｐｐｍ、Ｓの含有量は１０ｐｐｍ、Ｏ含有量は８０ｐｐｍ、Ｃ含有量は２０ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが５４ＭＯｅであり、参照例１に比べて１７％上昇していた。また、耐熱温度が１７０℃であり、参照例１に比べて６２％上昇していた。さらに、耐食性も参照例１に比べて非常に良好な結果を示した。
(Example 2)
A 2N level neodymium raw material was reduced to a 4N level by reducing and melting salt electrolysis of 3N level neodymium oxide using 4N level calcium, and 31 kg of it was produced. In addition, the iron raw material having a purity level of 3N was subjected to diaphragm electrolysis twice using an aqueous solution of catholyte in hydrochloric acid system (anolyte is sulfuric acid system) to obtain a purity level of 4N, and 68 kg of it was produced. Moreover, about the boron raw material, 1 kg of commercially available purity 2N level was prepared. Subsequent steps were performed under the same conditions as in Reference Example 1.
As a result, Table 1 shows the purity, magnetic properties, and heat-resistant temperature of the neodymium-based rare earth permanent magnet produced in Example 2. As shown in Table 1, the purity of the neodymium rare earth permanent magnet of Example 2 is 4N (99.99 wt%) level, the P content is 10 ppm, the S content is 10 ppm, the O content is 80 ppm, The C content was 20 ppm. At this time, the maximum energy product (BH) max was 54 MOe, which was 17% higher than that of Reference Example 1. The heat-resistant temperature was 170 ° C., which was 62% higher than that of Reference Example 1. Further, the corrosion resistance was very good as compared with Reference Example 1.
（実施例３）
純度２Ｎレベルのネオジム原料を、３Ｎレベルのネオジム酸化物を４Ｎレベルのカルシウムを用いて還元及び２回の溶融塩電解することにより純度５Ｎレベルとし、それを３１ｋｇ製造した。また、純度３Ｎレベルの鉄原料を、塩酸系の電解液を溶媒抽出により不純物を除去し、その液をカソライトとして用い、アノライトは硫酸系の水溶液の隔膜電解を２回繰り返すことにより純度５Ｎレベルとし、それを６８ｋｇ製造した。また、ボロン原料については、市販の純度６Ｎレベルを１ｋｇ用意した。その後の工程は、参照例１と同様の条件とした。
その結果、実施例３で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、実施例３のネオジム系希土類永久磁石の純度は５Ｎ（９９．９９９ｗｔ％）レベルであり、Ｐの含有量は＜１０ｐｐｍ、Ｓの含有量は＜１０ｐｐｍ、Ｏ含有量は＜１０ｐｐｍ、Ｃ含有量は＜１０ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが５８ＭＯｅであり、参照例１に比べて２６％上昇していた。また、耐熱温度が２２０℃であり、参照例１と比べて１１０％上昇していた。さらに、耐食性も参照例１に比べて非常に良好な結果を示した。
(Example 3)
A 2N level neodymium raw material was reduced to 3N level neodymium oxide by using 4N level calcium and subjected to molten salt electrolysis twice, and 31 kg of it was produced. Moreover, impurities were removed from the iron raw material with a purity level of 3N by solvent extraction with a hydrochloric acid-based electrolyte, and the solution was used as catholyte. 68 kg of it was produced. Moreover, about the boron raw material, 1 kg of commercially available 6N levels of purity was prepared. Subsequent steps were performed under the same conditions as in Reference Example 1.
As a result, the purity, magnetic characteristics, and heat-resistant temperature of the neodymium-based rare earth permanent magnet produced in Example 3 are shown in Table 1, respectively. As shown in Table 1, the purity of the neodymium rare earth permanent magnet of Example 3 is at a 5N (99.999 wt%) level, the P content is <10 ppm, the S content is <10 ppm, and the O content is <10 ppm, C content was <10 ppm. At this time, the maximum energy product (BH) max was 58 MOe, which was 26% higher than that of Reference Example 1. The heat-resistant temperature was 220 ° C., which was 110% higher than that of Reference Example 1. Further, the corrosion resistance was very good as compared with Reference Example 1.
［組成：２６Ｎｄ−５Ｄｙ−６８Ｆｅ−１Ｂ］
（参照例２）
市販の純度２Ｎレベルのネオジム原料を２６ｋｇ用意した。また、市販の純度３Ｎレベルの鉄を６８ｋｇ用意した。また、市販の純度２Ｎレベルのボロンを１ｋｇ用意した。さらに、市販の純度２Ｎレベルのジスプロシウム原料を５ｋｇ用意した。その後の工程は、参照例１と同様の条件とした。
その結果、参照例２で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、参照例２のネオジム系希土類永久磁石の純度は２Ｎ（９９ｗｔ％）レベルであり、Ｐの含有量は６４ｐｐｍ、Ｓの含有量は１６０ｐｐｍ、Ｏ含有量は１２００ｐｐｍ、Ｃ含有量は５６０ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが４１ＭＯｅであった。また、耐熱温度が１５０℃であり、耐熱性は後述する実施例４に比べて劣る結果をなった。
[Composition: 26Nd-5Dy-68Fe-1B]
(Reference Example 2)
26 kg of a commercially available neodymium raw material with a purity level of 2N was prepared. Moreover, 68 kg of commercially available iron having a purity level of 3N was prepared. Further, 1 kg of commercially available boron having a purity level of 2N was prepared. Furthermore, 5 kg of a commercially available dysprosium raw material having a purity level of 2N was prepared. Subsequent steps were performed under the same conditions as in Reference Example 1.
As a result, the purity, magnetic characteristics, and heat-resistant temperature of the neodymium rare earth permanent magnet produced in Reference Example 2 are shown in Table 1, respectively. As shown in Table 1, the purity of the neodymium rare earth permanent magnet of Reference Example 2 is at a 2N (99 wt%) level, the P content is 64 ppm, the S content is 160 ppm, the O content is 1200 ppm, and the C content is The amount was 560 ppm. At this time, the maximum energy product (BH) max was 41 MOe. Moreover, the heat resistant temperature was 150 ° C., and the heat resistance was inferior to that of Example 4 described later.
（実施例４）
純度２Ｎレベルのネオジム原料を、３Ｎレベルのネオジム酸化物を４Ｎレベルのカルシウムを用いて還元及び溶融塩電解することにより純度４Ｎレベルとし、それを２６ｋｇ製造した。また、純度３Ｎレベルの鉄原料を、カソライトを塩酸系（アノライトは硫酸系）の水溶液を用いた隔膜電解を２回繰り返すことにより純度４Ｎレベルとし、それを６８ｋｇ製造した。また、ボロン原料については、市販の純度２Ｎレベルを１ｋｇ用意した。また、純度２Ｎレベルのジスプロシウムを、真空蒸留法により純度４Ｎレベルとし、５ｋｇ用意した。その後の工程は、参照例１と同様の条件とした。
その結果、実施例４で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、実施例４のネオジム系希土類永久磁石の純度は４Ｎ（９９．９９ｗｔ％）レベルであり、Ｐの含有量は＜１０ｐｐｍ、Ｓの含有量は１０ｐｐｍ、Ｏ含有量は１７０ｐｐｍ、Ｃ含有量は２０ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが４４ＭＯｅであり、参照例２に比べて７％上昇していた。また、耐熱温度が１７０℃であり、参照例２に比べて１３％上昇していた。さらに、耐熱性も参照例２に比べて良好な結果を示していた。
Example 4
A 2N level neodymium raw material was reduced to a 4N level by reducing and melting salt electrolysis of 3N level neodymium oxide using 4N level calcium, and 26 kg of it was produced. Further, the iron raw material having a purity level of 3N was subjected to diaphragm electrolysis twice using a catholyte-based aqueous solution of hydrochloric acid (anorite is sulfuric acid) to obtain a purity level of 4N, and 68 kg was produced. Moreover, about the boron raw material, 1 kg of commercially available purity 2N level was prepared. Further, 5 kg of dysprosium having a purity level of 2N was prepared to a purity level of 4N by vacuum distillation. Subsequent steps were performed under the same conditions as in Reference Example 1.
As a result, the purity, magnetic characteristics, and heat-resistant temperature of the neodymium-based rare earth permanent magnet produced in Example 4 are shown in Table 1, respectively. As shown in Table 1, the purity of the neodymium rare earth permanent magnet of Example 4 is 4N (99.99 wt%) level, the P content is <10 ppm, the S content is 10 ppm, and the O content is 170 ppm. The C content was 20 ppm. At this time, the maximum energy product (BH) max was 44 MOe, which was 7% higher than that of Reference Example 2. The heat-resistant temperature was 170 ° C., which was 13% higher than that of Reference Example 2. Further, the heat resistance was better than that of Reference Example 2.
［組成：２１Ｎｄ−１０Ｄｙ−６８Ｆｅ−１Ｂ］
（参照例３）
市販の純度２Ｎレベルのネオジム原料を２１ｋｇ用意した。また、市販の純度３Ｎレベルの鉄を６８ｋｇ用意した。また、市販の純度２Ｎレベルのボロンを１ｋｇ用意した。さらに、市販の純度２Ｎレベルのジスプロシウム原料を１０ｋｇ用意した。その後の工程は、参照例１と同様の条件とした。
その結果、参照例３で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、参照例３のネオジム系希土類永久磁石の純度は２Ｎ（９９ｗｔ％）レベルであり、Ｐの含有量は８９ｐｐｍ、Ｓの含有量は２１０ｐｐｍ、Ｏ含有量は１５００ｐｐｍ、Ｃ含有量は６８０ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが３６ＭＯｅであった。また、耐熱温度が２２０℃であり、耐熱性は後述する実施例５に比べて劣る結果をなった。
[Composition: 21Nd-10Dy-68Fe-1B]
(Reference Example 3)
21 kg of a commercially available neodymium raw material with a purity level of 2N was prepared. Moreover, 68 kg of commercially available iron having a purity level of 3N was prepared. Further, 1 kg of commercially available boron having a purity level of 2N was prepared. Furthermore, 10 kg of commercially available dysprosium raw material having a purity level of 2N was prepared. Subsequent steps were performed under the same conditions as in Reference Example 1.
As a result, the purity, magnetic characteristics, and heat-resistant temperature of the neodymium rare earth permanent magnet produced in Reference Example 3 are shown in Table 1, respectively. As shown in Table 1, the purity of the neodymium-based rare earth permanent magnet of Reference Example 3 is 2N (99 wt%) level, the P content is 89 ppm, the S content is 210 ppm, the O content is 1500 ppm, and the C content is The amount was 680 ppm. At this time, the maximum energy product (BH) max was 36 MOe. Moreover, the heat-resistant temperature was 220 degreeC, and the heat resistance was inferior compared with Example 5 mentioned later.
（実施例５）
純度２Ｎレベルのネオジム原料を、３Ｎレベルのネオジム酸化物を４Ｎレベルのカルシウムを用いて還元及び溶融塩電解することにより純度４Ｎレベルとし、それを２１ｋｇ製造した。また、純度３Ｎレベルの鉄原料を、カソライトを塩酸系（アノライトは硫酸系）の水溶液を用いた隔膜電解を２回繰り返すことにより純度４Ｎレベルとし、それを６８ｋｇ製造した。また、ボロン原料については、市販の純度２Ｎレベルを１ｋｇ用意した。また、純度２Ｎレベルのジスプロシウムを、真空蒸留法により純度４Ｎレベルとし、１０ｋｇ用意した。その後の工程は、参照例１と同様の条件とした。
その結果、実施例５で作製したネオジム系希土類永久磁石の純度、磁気特性及び耐熱温度をそれぞれ表１に示す。表１に示すように、実施例５のネオジム系希土類永久磁石の純度は４Ｎ（９９．９９ｗｔ％）レベルであり、Ｐの含有量は＜１０ｐｐｍ、Ｓの含有量は１０ｐｐｍ、Ｏ含有量は２５０ｐｐｍ、Ｃ含有量は３０ｐｐｍであった。このとき、最大エネルギー積（ＢＨ）ｍａｘが４０ＭＯｅであり、参照例３に比べて１１％上昇していた。また、耐熱温度が２５０℃であり、参照例３に比べて１４％上昇していた。さらに耐熱性も参照例３に比べて良好な結果を示していた。
(Example 5)
A 2N level neodymium raw material was reduced to 4N level by reducing and melting salt electrolysis of 3N level neodymium oxide using 4N level calcium, and 21 kg of it was produced. Further, the iron raw material having a purity level of 3N was subjected to diaphragm electrolysis twice using a catholyte-based aqueous solution of hydrochloric acid (anorite is sulfuric acid) to obtain a purity level of 4N, and 68 kg was produced. Moreover, about the boron raw material, 1 kg of commercially available purity 2N level was prepared. Further, dysprosium having a purity level of 2N was adjusted to a purity level of 4N by vacuum distillation, and 10 kg was prepared. Subsequent steps were performed under the same conditions as in Reference Example 1.
As a result, the purity, magnetic characteristics, and heat-resistant temperature of the neodymium-based rare earth permanent magnet produced in Example 5 are shown in Table 1, respectively. As shown in Table 1, the purity of the neodymium-based rare earth permanent magnet of Example 5 is 4N (99.99 wt%) level, the P content is <10 ppm, the S content is 10 ppm, and the O content is 250 ppm. The C content was 30 ppm. At this time, the maximum energy product (BH) max was 40 MOe, which was 11% higher than that of Reference Example 3. Further, the heat resistant temperature was 250 ° C., which was 14% higher than that of Reference Example 3. Furthermore, the heat resistance was better than that of Reference Example 3.
本発明のＮｄ−Ｆｅ−Ｂ系希土類永久磁石は、超高純度技術を磁性材料に応用することにより、磁気特性を格段に向上させることができ、さらに、磁性材料特有の弱点である耐熱性、耐食性を改善することができるので、製造プロセスを煩雑にすることなく、高性能の永久磁石の提供に有用である。 The Nd-Fe-B rare earth permanent magnet of the present invention can significantly improve magnetic properties by applying ultra-high purity technology to a magnetic material, and further, heat resistance, which is a weak point unique to magnetic materials, Since the corrosion resistance can be improved, it is useful for providing a high-performance permanent magnet without complicating the manufacturing process.
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| CN113481545A (en) * | 2016-12-16 | 2021-10-08 | 包头稀土研究院 | Lanthanum-iron alloy |
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