JP3865180B2 - Heat-resistant rare earth alloy anisotropic magnet powder - Google Patents
Heat-resistant rare earth alloy anisotropic magnet powder Download PDFInfo
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- JP3865180B2 JP3865180B2 JP26414998A JP26414998A JP3865180B2 JP 3865180 B2 JP3865180 B2 JP 3865180B2 JP 26414998 A JP26414998 A JP 26414998A JP 26414998 A JP26414998 A JP 26414998A JP 3865180 B2 JP3865180 B2 JP 3865180B2
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- 239000000843 powder Substances 0.000 title claims description 106
- 229910052761 rare earth metal Inorganic materials 0.000 title claims description 97
- 229910045601 alloy Inorganic materials 0.000 title claims description 75
- 239000000956 alloy Substances 0.000 title claims description 75
- 150000002910 rare earth metals Chemical class 0.000 title claims description 70
- 238000010438 heat treatment Methods 0.000 claims description 24
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 19
- 229910052771 Terbium Inorganic materials 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 15
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 13
- 150000001875 compounds Chemical class 0.000 claims description 13
- 239000001257 hydrogen Substances 0.000 claims description 13
- 229910052739 hydrogen Inorganic materials 0.000 claims description 13
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims description 12
- 150000004678 hydrides Chemical class 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 229910052727 yttrium Inorganic materials 0.000 claims description 8
- 239000011247 coating layer Substances 0.000 claims description 7
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical group [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 7
- 238000009792 diffusion process Methods 0.000 claims description 6
- 238000002844 melting Methods 0.000 claims description 6
- 230000008018 melting Effects 0.000 claims description 6
- 239000011347 resin Substances 0.000 claims description 5
- 229920005989 resin Polymers 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 239000010410 layer Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims 5
- 239000009261 D 400 Substances 0.000 claims 1
- 238000000137 annealing Methods 0.000 claims 1
- 229910001325 element alloy Inorganic materials 0.000 description 19
- 239000000463 material Substances 0.000 description 11
- 239000002245 particle Substances 0.000 description 9
- 238000000034 method Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 229910052779 Neodymium Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910052777 Praseodymium Inorganic materials 0.000 description 4
- 239000010953 base metal Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 230000005381 magnetic domain Effects 0.000 description 4
- 239000004570 mortar (masonry) Substances 0.000 description 4
- 239000006247 magnetic powder Substances 0.000 description 3
- 238000005275 alloying Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000000748 compression moulding Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000005011 phenolic resin Substances 0.000 description 2
- 229920001187 thermosetting polymer Polymers 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 229910001172 neodymium magnet Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000000700 radioactive tracer Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/026—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets protecting methods against environmental influences, e.g. oxygen, by surface treatment
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
Description
【０００１】
【発明の属する技術分野】
本発明は，各種モーター， アクチュエーター等に用いることが可能な高保磁力を有する強力な永久磁石用希土類磁石の技術分野に属する．
【０００２】
【従来の技術】
強力な希土類合金異方性磁石粉末として，高温水素熱処理による製造方法が特開平１０−１３５０１９号公報（従来技術１）に開示されている．また，高保磁力を有する希土類合金異方性磁石粉末の製造方法として，希土類元素と鉄とホウ素とを主成分とする希土類磁石の希土類元素の一部を異方性磁場の大きい希土類元素（Ｄｙ，Ｔｂ）と置換する方法が，例えば特開平９−１６５６０１号公報（従来技術２）に開示されている．
【０００３】
従来技術１の希土類合金異方性磁石粉末は，大きな磁気異方性を有し，かつ室温ではある程度の大きな保磁力を有するが，８０℃を越えるような温度では保磁力が小さくなり，使用できない．実際に従来技術１の希土類合金異方性磁石粉末を作製し保磁力の評価を行ったところ，室温では９５５ｋＡ／ｍであるが，８０℃では７２０ｋＡ／ｍ ，１２０℃では４００ｋＡ／ｍとなっている．
【０００４】
また，従来技術２の希土類合金異方性磁石粉末は，ＲＥ：１１〜１５ａｔ％（但し，ＲＥはＲ１とＲ２からなり，Ｒ１はＹを含む希土類元素の少なくとも１種で，ＰｒまたはＮｄの１種または２種をＲ１のうち９０ａｔ％異常現有し，Ｒ２はＴｂ，Ｄｙのうち１種もしくは２種で，かつＲ１とＲ２のａｔ％比は０．００３＜Ｒ２／Ｒ１＜０．０６の関係を満たす），Ｔ：７６〜８４ａｔ％（但し，ＴはＦｅまたはＦｅの一部を５０％以下のＣｏで置換可能），ＭＥ：０．０５〜５ａｔ％（但し，ＭＥはＧａ，Ｚｒ，Ｎｂ，Ｈｆ，Ｔａ，Ｗのうち１種または２種以上），Ｂ：５〜９ａｔ％で，かつＲ２とＭＥとＣｏのａｔ％比において（Ｒ２＋ＭＥ＋Ｃｏ／１０）＜６の関係を満たすことにより，高い磁化と大きな保磁力を両立できることを特徴としている．しかし，実際に作製してみると，安定した特性が得られないことが分かった．なぜならば， 合金鋳塊作製の際，異方性磁場の大きい希土類元素（Ｄｙ，Ｔｂ）は極微量しか添加しないため，かつ，蒸気圧が大きいため組成の制御が非常に困難であり，故に，安定した特性が得られない．例えば， Ｒ２／Ｒ１＜０．0２の場合では，異方性磁場の大きい希土類元素（Ｄｙ，Ｔｂ）を置換しない場合に比べて，保磁力の向上はほとんど見られず，また，異方性磁場の大きい希土類元素（Ｄｙ，Ｔｂ）を添加すると，急激な異方性の低下のため十分なエネルギー積が得られない．
【０００５】
【発明が解決しようとする課題】
そこで本願発明は，８０℃を越えるような温度においても十分な保磁力を保ち，かつ，大きな磁気異方性を有する耐熱希土類合金異方性磁石粉末と安定した生産が可能なその製造方法を提供することを課題とする．
【０００６】
８０℃を越えるような温度で十分な保磁力を確保する方法は，（１）保磁力の温度係数の改善，（２）８０℃を越えるような温度で保磁力が低下しても十分な値が確保できるよう，室温での保磁力を向上させる，の２点が従来から知られている．
【０００７】
上記（１）の保磁力の温度係数を改善する方法は，磁気特性の中核である正方晶構造Nd2Fe14B型化合物相の磁気異方性の温度依存性が大きいため，実現は困難である．これに対し，上記（２）の室温での保磁力の向上は，例えば，特開平９−１６５６０１号公報に開示されている．
【０００８】
本発明者は，希土類合金異方性磁石粉末の逆磁区の発生場所を検討し，逆磁区発生を抑制する方法を発見し，高保磁力を有し，大きな磁気異方性を有する希土類合金異方性磁石粉末とその製造方法を発明した．
本発明はかかる見解の元で完成されたものである．
【０００９】
【課題を解決するための手段】
本発明の耐熱希土類合金異方性磁石粉末は、異方性希土類磁石粉末の表面に、Ｎｄ，Ｄｙ，Ｔｂ，Ｐｒ（以下、Ｍ系元素という）からなるコーティング層を持つことを特徴とする。
【００１０】
また、本発明の耐熱希土類合金異方性磁石粉末は、異方性希土類磁石粉末の表面に、Ｎｄ，Ｄｙ，Ｔｂ，Ｐｒ の一種または２種以上で構成される合金（以下、Ｍ系元素合金という）からなるコーティング層を持つことを特徴とする。
【００１１】
さらに、本発明の耐熱希土類合金異方性磁石粉末は、前記Ｍ系元素に対して、高温水素熱処理温度ＴHに比べ融点ＴMが５００°C≦ＴM≦ＴH＋１００°Cになるような元素（以下、Ｌ系元素という）の一種もしくは２種以上を合金化させた合金（以下、ＭＬ系合金という）からなるコーティング層を持つことを特徴とする。
【００１２】
本発明の耐熱希土類合金異方性磁石粉末は、前記のＭ系元素合金に、Ｌ系元素の一種もしくは２種以上を合金化させたＭＬ系合金からなるコーティング層を持つことを特徴とする。
【００１３】
本発明の耐熱希土類合金異方性磁石粉末は、異方性希土類磁石粉末の表面に、ＤｙＣｏ合金からなるコーティング層を持つことを特徴とする。
【００１４】
本発明の耐熱希土類合金異方性磁石粉末は、異方性希土類磁石粉末の表面に、当該異方性希土類磁石粉末の正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物（Ｒはイットリウムを含む希土類元素のうち１種または２種以上からなる希土類元素）のＲの一部と、すくなくともＭ系元素（Ｎｄ，Ｄｙ，Ｔｂ）のうち１種または２種以上が置換した拡散層を持つことを特徴とする。
【００１５】
本発明の耐熱希土類合金異方性磁石粉末の製造方法は、正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物（Ｒはイットリウムを含む希土類元素のうち１種または２種以上からなる希土類元素）からなる異方性希土類磁石粉末と、Ｍ系元素粉末、Ｍ系元素合金粉末、又は、ＭＬ系合金粉末の両者を、ａｔ％比Ｘ＝ｍ／(ｒ＋ｍ）×１００（ｍはＭ系元素、Ｍ系元素合金、又は、ＭＬ系合金におけるＭ系元素の全ａｔ％）（ｒは異方性希土類磁石粉末中における希土類元素の全ａｔ％）を０．０３＜Ｘ＜２４に特定して混合し、該混合物を真空中あるいは不活性ガス雰囲気中において熱処理温度ＴDを４００℃≦ＴD≦高温水素処理温度ＴH＋５０°Cに保持することを特徴とする．
また、本発明の耐熱希土類合金異方性磁石粉末の製造方法は、正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物（Ｒはイットリウムを含む希土類元素のうち１種または２種以上からなる希土類元素）からなる異方性希土類磁石粉末と、Ｍ系元素水素化物粉末、Ｍ系元素合金水素化物粉末、又は、ＭＬ系合金水素化物粉末の両者を、ａｔ％比Ｘ＝ ｍ／(ｒ＋ｍ）×１００（ｍはＭ系元素、Ｍ系元素合金、又は、ＭＬ系合金におけるＭ系元素の全ａｔ％）（ｒは異方性希土類磁石粉末中における希土類元素の全ａｔ％）を０．０３＜Ｘ＜２４に特定して混合し、該混合物を真空中あるいは不活性ガス雰囲気中において熱処理温度ＴDを４００℃≦ＴD≦高温水素処理温度ＴH＋５０°Cに保持することを特徴とする．
また、本発明のボンド磁石の製造方法は、前記のいずれかの耐熱希土類合金異方性磁石粉末に樹脂または低融点金属を混合し成形固化することを特徴とする．
【００１６】
なお，異方性磁石粉末の最大エネルギー積（以下（ＢＨ）ｍａｘと称す），残留磁束密度（以下Ｂｒと称す）には，通常のＢＨトレーサーが使用できないため，本発明では（ＢＨ）ｍａｘ ，Ｂｒの測定方法として次の方法を採用した．まず異方性磁石粉末を２１２μm以下の粒径のものに分級して用いた．そして反磁場が０．２になるように成形し．磁場中で配向後４５６８ｋＡ／ｍで着磁し，ＶＳＭで測定して（ＢＨ）ｍａｘ ，Ｂｒを求めた．
【００１７】
【発明の実施の形態】
従来の異方性磁石粉末の逆磁区の発生場所は，粉末の表面である．粉末表面の粗さ，磁気特性の担い手であるＲ２Ｆｅ１４Ｂの粉末表面のＲ原子の結合が切れているためと考えられる．すなわち，粉末表面をスムーズにし， 磁気特性の担い手であるＲ２Ｆｅ１４Ｂの粉末表面のＲ原子が何らかの原子と結合していればよい．従って，Ｒ２Ｆｅ１４ＢのＲの異方性磁場以上の元素が少なくとも逆磁区発生場所である粉末表面に結合されていれば保磁力が向上する． Ｒ２Ｆｅ１４ＢのＲの異方性磁場以上の元素として，Ｎｄ，Ｄｙ，Ｔｂ，Ｐｒから選ばれる１種または２種以上が利用できる．中でもコスト及び磁気特性の理由からＤｙを用いることが好ましい．
【００１８】
粉末表面をスムーズにし， 磁気特性の担い手であるＲ２Ｆｅ１４Ｂの粉末表面のＲ原子がＭ系元素と結合していればよいため，極微量のＭ系元素， Ｍ系元素合金， ＭＬ系元素合金ができる限り均一かつ薄く粉末表面にあればよい．従って，Ｍ系元素，Ｍ系元素合金，ＭＬ系元素合金中のＭの下限を０．０３＜ｍ／（ｒ＋ ｍ ）×１００とする． これに対し， Ｍ系元素， Ｍ系元素合金， ＭＬ系元素合金の量が大きければ，より均一に粉末表面にＲと結合できるが，（ＢＨ）ｍａｘが低下する．従って， ＲあるいはＲ合金の上限をｍ／（ｒ＋ ｍ ）×１００＜２４とする．
【００１９】
耐熱希土類合金異方性磁石粉末の製造方法において，正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物の異方性磁石粉末とＭあるいはＭ合金を混合させた後，4００℃以下の熱処理では，拡散が起こりにくく，正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物中のＲとＭ系元素，Ｍ系元素合金，ＭＬ系元素合金中のＭとの結合が困難である．正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物の異方性磁石粉末は，通常，高温水素熱処理され，微細組織を有しているため，高温水素熱処理温度を大きく越えた温度での熱処理は急激な結晶粒の粗大化が起こる．従って，熱処理条件は４００℃から高温水素処理温度ＴH＋５０°Cとした．
【００２０】
【発明の効果】
８０℃を越えるような温度においても十分な保磁力を保ち，かつ，大きな磁気異方性を有する永久磁石用希土類合金粉末と安定した生産が可能なその製造方法を提供できる．
【００２１】
【実施例】
以下，実施例により具体的に説明する．
（実施例１）平均粒度が１０μm〜５０００μmで少なくとも８０ｖｏｌ％以上の正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物の異方性磁石粉末を２１２μm以下に分級したものを母材粉末とした．母材粉末の磁気特性を表１に示す．
【００２２】
【表１】
【００２３】
【表２】
【００２４】
【表３】
具体的には，異方性希土類磁石粉末とＭＬ系合金粉末の両者を、ａｔ％比Ｘ＝ｍ／(ｒ＋ｍ）×１００（ｍはＭＬ系合金におけるＭ系元素の全ａｔ％）（ｒは異方性希土類磁石粉末中における希土類元素の全ａｔ％）のＸを0．１〜２４になるよう混合した．試料として約５０ｇと極めて少なくし，真空チャンバー内に入れ，拡散ポンプで真空引きしながら所定の温度，時間で熱処理を行った．熱処理終了後は，高純度アルゴンガスを導入することにより急冷した．これにより希土類合金異方性磁石粉末を製造した．得られた希土類合金異方性磁石粉末の磁気特性を測定し，これを表３に示す．表３中のＮｏ．１７〜２３の結果を用いて，保磁力に及ぼす熱処理温度の影響を図１に示す．
図１より９００℃では急激に保磁力が低下している．これは，母材の高温水素熱処理の温度が８２０℃であり，母材の結晶粒が成長したためである．すなわち，母材の高温水素熱処理温度よりも明らかに高い温度で熱処理をすると逆に保磁力が低下することが分かる．一方，ＭＬ系合金の融点より約１００℃低い温度で熱処理を行っても保磁力の増加している．また，均一に母材粉末表面にＭＬ系合金が結合するためには，ＭＬ系合金の平均粒度も重要なパラメーターの１つとなる． 表３中のＮｏ．２８，３３〜３７の結果を用いて，保磁力に及ぼすＭＬ系合金の平均粒度の影響を図２に示す．図２よりＭＬ系合金の平均粒度が小さいと保磁力は高くなる． 平均粒度が小さいとより均一に母材粉末表面に結合するためと考えられる． また， ＭＬ系合金の添加量の調査も行った．表３中のＮｏ．２７〜３２の結果を用いて，最大エネルギー積，保磁力に及ぼす異方性希土類磁石粉末中の全希土類金属とＭＬ系合金の全希土類金属のａｔ％比の影響をそれぞれ図３，４に示す．また，合わせて，合金鋳塊を作製する時にＤｙを添加した結果も示す． 図３，４より，合金鋳塊法と比較して，少ないＤｙ量で大きい最大エネルギー積と高い保磁力が得られていることが分かる． 一方，母材のみの熱処理では保磁力の増加はない．また，図３，４中には示していないが，異方性希土類磁石粉末中の全希土類金属とＭＬ系合金の全希土類金属のａｔ％比Ｘが２４の場合は，最大エネルギー積が母材のみに比べて大きく低下している．
【００２６】
得られた磁石粉末（表３中のＮｏ．２０）を用い，熱硬化性樹脂としてフェノール樹脂を磁石粉末９８ｇに対して２ｇ使用し，型内で２．５Ｔの磁場を作用させながら圧縮成形してボンド磁石を得た．また，比較材に表３中のＮｏ．２の磁石粉末を用いた．得られたボンド磁石を用いて室温，８０℃及び１２０℃での保磁力をＶＳＭにて測定し，表４に示す．
【００２７】
【表４】
【００２８】
（実施例２）実施例１と同じく，平均粒度が１０μm〜５０００μmで少なくとも８０ｖｏｌ％以上の正方晶構造Ｒ２Ｆｅ１４Ｂ型化合物の異方性磁石粉末を２１２μm以下に分級したものを母材粉末とした．母材粉末の磁気特性を表１に示す．また， Ｍ系元素，Ｍ系元素合金，ＭＬ系元素合金の水素化物を温度：８００℃，時間：１ｈ，水素圧力：０．１ＭＰａの条件で作製し，乳鉢あるいは振動ミルで粉砕し，母材粉末と水素化物粉末を乳鉢にて混合した．水素化物の平均粒度を表５に示す．
【００２９】
【表５】
【００３０】
【表６】
具体的には，異方性希土類磁石粉末とＭ系元素，Ｍ系元素合金，ＭＬ系合金粉末の水素化物の両者を、ａｔ％比Ｘ＝ｍ／(ｒ＋ｍ）×１００（ｍはＭ系元素、Ｍ系元素合金、又は、ＭＬ系合金の水素化物におけるＭ系元素の全ａｔ％）（ｒは異方性希土類磁石粉末中における希土類元素の全ａｔ％）のＸを８になるよう混合した．実施例１と同様に， 試料として約５０ｇと極めて少なくし，真空チャンバー内に入れ，拡散ポンプで真空引きしながら所定の温度，時間で熱処理を行った．このとき，水素化物が脱水素され， Ｍ系元素，Ｍ系元素合金，ＭＬ系合金単体となる．熱処理終了後は，高純度アルゴンガスを導入することにより急冷した．これにより希土類合金異方性磁石粉末を製造した．得られた希土類合金異方性磁石粉末の磁気特性を測定した．これを表６に示す．異方性磁場が大きい元素ほどより保磁力が増加する傾向にあることがわかる．
【００３２】
得られた磁石粉末（表６中のＮｏ．６０）を用い，実施例１と同様に，熱硬化性樹脂としてフェノール樹脂を磁石粉末９８ｇに対して２ｇ使用し，型内で２．５Ｔの磁場を作用させながら圧縮成形してボンド磁石を得た． 比較材は表４中のＮｏ．５２である． 得られたボンド磁石を用いて室温，８０℃及び１２０℃での保磁力をＶＳＭにて測定し，表７に示す．
【００３３】
【表７】
【図面の簡単な説明】
【図１】希土類合金異方性磁石粉末とＭＬ系合金（ＤｙＣｏ）の混合体の保磁力に及ぼす熱処理温度の影響を示す図である．
【図２】希土類合金異方性磁石粉末とＭＬ系合金（ＤｙＣｏ）の混合体の保磁力に及ぼすＭＬ系合金（ＤｙＣｏ）の平均粒度の影響を示す図である．
【図３】希土類合金異方性磁石粉末とＭＬ系合金（ＤｙＣｏ）の混合体の最大エネルギー積に及ぼす希土類磁石粉末中の全希土類金属とＭＬ系合金の全希土類金属のａｔ％比Ｘの影響を示す図である．
【図４】希土類合金異方性磁石粉末とＭＬ系合金（ＤｙＣｏ）の混合体の保磁力に及ぼす希土類磁石粉末中の全希土類金属とＭＬ系合金の全希土類金属のａｔ％比Ｘの影響を示す図である．[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of powerful permanent magnets for permanent magnets having high coercive force that can be used for various motors, actuators, and the like.
[0002]
[Prior art]
As a strong rare earth alloy anisotropic magnet powder, a manufacturing method by high-temperature hydrogen heat treatment is disclosed in Japanese Patent Laid-Open No. 10-135019 (Prior Art 1). Further, as a method for producing a rare earth alloy anisotropic magnet powder having a high coercive force, a part of a rare earth element of a rare earth magnet mainly composed of a rare earth element, iron and boron is converted into a rare earth element (Dy, A method for replacing Tb) is disclosed, for example, in JP-A-9-165601 (Prior Art 2).
[0003]
The rare earth alloy anisotropic magnet powder of Prior Art 1 has a large magnetic anisotropy and a large coercive force to some extent at room temperature, but the coercive force becomes small at temperatures exceeding 80 ° C. and cannot be used. . Actually, when the rare earth alloy anisotropic magnet powder of the
[0004]
Further, the rare earth alloy anisotropic magnet powder of
[0005]
[Problems to be solved by the invention]
Accordingly, the present invention provides a heat-resistant rare earth alloy anisotropic magnet powder having a sufficient coercive force even at a temperature exceeding 80 ° C. and having a large magnetic anisotropy, and a production method thereof capable of stable production. The task is to do.
[0006]
The methods to ensure a sufficient coercive force at a temperature exceeding 80 ° C are (1) improvement of the temperature coefficient of the coercive force, and (2) a sufficient value even if the coercive force is decreased at a temperature exceeding 80 ° C. There are two known points to improve the coercive force at room temperature.
[0007]
The method of improving the temperature coefficient of the coercive force (1) above is difficult to realize because the temperature dependence of the magnetic anisotropy of the tetragonal Nd2Fe14B type compound phase, which is the core of the magnetic properties, is large. On the other hand, the improvement of the coercive force at room temperature (2) is disclosed in, for example, Japanese Patent Laid-Open No. 9-165601.
[0008]
The present inventor has examined the occurrence location of the reverse magnetic domain of the rare earth alloy anisotropic magnet powder, discovered a method for suppressing the occurrence of the reverse magnetic domain, has a high coercive force, and has a large magnetic anisotropy. Have invented a conductive magnet powder and its manufacturing method.
The present invention has been completed based on this view.
[0009]
[Means for Solving the Problems]
The heat-resistant rare earth alloy anisotropic magnet powder of the present invention is characterized by having a coating layer made of Nd, Dy, Tb, Pr (hereinafter referred to as M-based element) on the surface of the anisotropic rare earth magnet powder.
[0010]
The heat-resistant rare earth alloy anisotropic magnet powder of the present invention is an alloy composed of one or more of Nd, Dy, Tb, Pr on the surface of the anisotropic rare earth magnet powder (hereinafter referred to as M-based element alloy). It is characterized by having a coating layer consisting of.
[0011]
Furthermore, the heat-resistant rare earth alloy anisotropic magnet powder of the present invention has a melting point T M of 500 ° C. ≦ T M ≦ T H + 100 ° C. compared to the high-temperature hydrogen heat treatment temperature T H for the M element. It is characterized by having a coating layer made of an alloy (hereinafter referred to as ML alloy) obtained by alloying one or more of these elements (hereinafter referred to as L-based elements).
[0012]
The heat-resistant rare earth alloy anisotropic magnet powder of the present invention is characterized by having a coating layer made of an ML-based alloy obtained by alloying the above-mentioned M-based element alloy with one or more L-based elements.
[0013]
The heat-resistant rare earth alloy anisotropic magnet powder of the present invention has a coating layer made of a DyCo alloy on the surface of the anisotropic rare earth magnet powder.
[0014]
The heat-resistant rare earth alloy anisotropic magnet powder of the present invention has a tetragonal structure R2Fe14B type compound (R is one kind of rare earth elements containing yttrium or the like) on the surface of the anisotropic rare earth magnet powder. It is characterized by having a diffusion layer in which a part of R of rare earth elements composed of two or more types and at least one or more of M-based elements (Nd, Dy, Tb) are substituted.
[0015]
The method for producing a heat-resistant rare earth alloy anisotropic magnet powder of the present invention comprises an anisotropic rare earth magnet comprising a tetragonal structure R2Fe14B type compound (where R is a rare earth element comprising one or more of yttrium-containing rare earth elements). Powder, M-type element powder, M-type element alloy powder, or ML-type alloy powder are mixed at% ratio X = m / (r + m) × 100 (where m is an M-type element, M-type element alloy, or The total amount of M-based elements in the ML-based alloy (r is the total at% of rare-earth elements in the anisotropic rare-earth magnet powder) is specified as 0.03 <X <24 and mixed, and the mixture is vacuumed Alternatively, the heat treatment temperature T D is maintained at 400 ° C. ≦ T D ≦ high temperature hydrogen treatment temperature T H + 50 ° C. in an inert gas atmosphere.
In addition, the method for producing a heat-resistant rare earth alloy anisotropic magnet powder of the present invention comprises an anisotropy comprising a tetragonal structure R2Fe14B type compound (where R is a rare earth element comprising one or more of yttrium-containing rare earth elements). Both the rare earth magnet powder, M-based element hydride powder, M-based element alloy hydride powder, or ML-based alloy hydride powder, at% ratio X = m / (r + m) × 100 (where m is an M-based element) , M-based element alloy or ML-based alloy in total at% of M-based element) (r is the total at% of rare-earth element in anisotropic rare earth magnet powder) is specified as 0.03 <X <24 The mixture is mixed, and the heat treatment temperature T D is maintained at 400 ° C. ≦ T D ≦ high temperature hydrogen treatment temperature T H + 50 ° C. in a vacuum or in an inert gas atmosphere.
The method for producing a bonded magnet according to the present invention is characterized in that any one of the above heat-resistant rare earth alloy anisotropic magnet powders is mixed with a resin or a low-melting-point metal and solidified by molding.
[0016]
In the present invention, since the normal BH tracer cannot be used for the maximum energy product (hereinafter referred to as (BH) max) and the residual magnetic flux density (hereinafter referred to as Br) of the anisotropic magnet powder, (BH) max, The following method was adopted as a method for measuring Br. First, anisotropic magnet powder was classified into particles having a particle size of 212 μm or less. Then, mold so that the demagnetizing field is 0.2. After orientation in a magnetic field, it was magnetized at 4568 kA / m and measured by VSM to obtain (BH) max and Br.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The location of the reverse magnetic domain of the conventional anisotropic magnet powder is on the surface of the powder. This is thought to be because the R atom bonds on the powder surface of R2Fe14B, which is responsible for the roughness and magnetic properties of the powder surface, are broken. In other words, the powder surface should be smooth, and R atoms on the powder surface of R2Fe14B, which is responsible for magnetic properties, should be bonded to some kind of atom. Therefore, the coercive force is improved if an element having an anisotropic magnetic field equal to or greater than the R anisotropic magnetic field of R2Fe14B is bonded to the powder surface where the reverse magnetic domain is generated. One or more elements selected from Nd, Dy, Tb, and Pr can be used as an element having an anisotropic magnetic field greater than or equal to the R magnetic field of R2Fe14B. Of these, Dy is preferably used for reasons of cost and magnetic properties.
[0018]
Since the surface of the powder of R2Fe14B, which is responsible for the magnetic properties, needs to be bonded to the M-based element, the powder surface is smooth, so that a very small amount of M-based element, M-based element alloy, and ML-based element alloy can be produced. It should be as uniform and thin as possible on the powder surface. Therefore, the lower limit of M in the M element, M element alloy, and ML element alloy is 0.03 <m / (r + m) × 100. On the other hand, if the amount of M-based element, M-based element alloy, and ML-based element alloy is large, R can be more uniformly bonded to the powder surface, but (BH) max decreases. Therefore, the upper limit of R or R alloy is m / (r + m) × 100 <24.
[0019]
In the method of manufacturing a heat-resistant rare earth alloy anisotropic magnet powder, a tetragonal structure R2Fe14B type compound anisotropic magnet powder and M or M alloy are mixed, and then heat treatment at 400 ° C. or less hardly causes diffusion. It is difficult to bond R in the structure R2Fe14B type compound with M in the M element, M element alloy, and ML element alloy. Since anisotropic magnet powder of tetragonal structure R2Fe14B type compound is usually subjected to high-temperature hydrogen heat treatment and has a fine structure, heat treatment at a temperature greatly exceeding the high-temperature hydrogen heat treatment temperature causes rapid grain coarsening Happens. Therefore, the heat treatment conditions were set from 400 ° C. to the high temperature hydrogen treatment temperature T H + 50 ° C.
[0020]
【The invention's effect】
It is possible to provide a rare earth alloy powder for permanent magnets having a sufficient coercive force even at a temperature exceeding 80 ° C. and having a large magnetic anisotropy and a production method capable of stable production.
[0021]
【Example】
In the following, this will be described in detail by way of examples.
(Example 1) An anisotropic magnetic powder of a tetragonal structure R2Fe14B type compound having an average particle size of 10 µm to 5000 µm and at least 80 vol% or more was classified to 212 µm or less was used as a base material powder. Table 1 shows the magnetic properties of the base metal powder.
[0022]
[Table 1]
[0023]
[Table 2]
[0024]
[Table 3]
Specifically, both the anisotropic rare earth magnet powder and the ML alloy powder are divided into at% ratio X = m / (r + m) × 100 (m is the total at% of the M element in the ML alloy) (r is The X of 0.1 to 24 was mixed so that X of all rare earth elements in the anisotropic rare earth magnet powder was 0.1 to 24. The sample was very small, about 50 g, placed in a vacuum chamber, and heat-treated at a predetermined temperature and time while evacuating with a diffusion pump. After the heat treatment, it was quenched by introducing high purity argon gas. This produced rare-earth alloy anisotropic magnet powder. The magnetic properties of the obtained rare earth alloy anisotropic magnet powder were measured and are shown in Table 3. No. in Table 3 Figure 1 shows the effect of heat treatment temperature on the coercive force using the results of 17-23.
As shown in Fig. 1, the coercive force suddenly decreases at 900 ° C. This is because the temperature of the high temperature hydrogen heat treatment of the base material was 820 ° C., and the crystal grains of the base material grew. In other words, it can be seen that the coercive force decreases conversely when the heat treatment is performed at a temperature clearly higher than the high temperature hydrogen heat treatment temperature of the base metal. On the other hand, the coercive force increases even when heat treatment is performed at a temperature about 100 ° C. lower than the melting point of the ML alloy. In addition, the average particle size of the ML alloy is one of the important parameters in order for the ML alloy to bond uniformly to the surface of the base powder. No. in Table 3 Using the results of Nos. 28 and 33 to 37, Fig. 2 shows the influence of the average grain size of the ML alloy on the coercive force. From Fig. 2, the coercive force increases when the average grain size of the ML-based alloy is small. This is probably because when the average particle size is small, it is more uniformly bonded to the surface of the base powder. We also investigated the amount of ML alloy added. No. in Table 3 Using the results of 27-32, the effects of the at% ratio of all rare earth metals in anisotropic rare earth magnet powder and all rare earth metals of ML-based alloy on the maximum energy product and coercive force are shown in FIGS. . In addition, the results of adding Dy when producing an alloy ingot are also shown. 3 and 4, it can be seen that a large maximum energy product and a high coercive force are obtained with a small amount of Dy, compared with the alloy ingot method. On the other hand, the coercive force does not increase by heat treatment using only the base metal. Although not shown in FIGS. 3 and 4, when the at% ratio X of the total rare earth metal in the anisotropic rare earth magnet powder to the total rare earth metal in the ML alloy is 24, the maximum energy product is the base material. Compared to only, it is greatly reduced.
[0026]
Using the obtained magnet powder (No. 20 in Table 3), 2 g of phenol resin was used as thermosetting resin for 98 g of magnet powder, and compression molding was performed while applying a 2.5 T magnetic field in the mold. A bonded magnet was obtained. In addition, as a comparative material, No. Two magnet powders were used. Using the obtained bonded magnet, coercive force at room temperature, 80 ° C. and 120 ° C. was measured by VSM and shown in Table 4.
[0027]
[Table 4]
[0028]
(Example 2) As in Example 1, an anisotropic magnet powder of a tetragonal structure R2Fe14B type compound having an average particle size of 10 µm to 5000 µm and at least 80 vol% or more was classified to 212 µm or less. Table 1 shows the magnetic properties of the base metal powder. In addition, hydrides of M-based elements, M-based element alloys, and ML-based element alloys are prepared under conditions of temperature: 800 ° C., time: 1 h, hydrogen pressure: 0.1 MPa, and pulverized with a mortar or vibration mill. The powder and hydride powder were mixed in a mortar. Table 5 shows the average particle size of the hydride.
[0029]
[Table 5]
[0030]
[Table 6]
Specifically, both the anisotropic rare earth magnet powder and the hydride of the M-based element, M-based element alloy, and ML-based alloy powder are mixed at% ratio X = m / (r + m) × 100 (m is the M-based element) , M type element alloy, or ML type alloy hydride, M type element total at%) (r is total rare earth element total at% in anisotropic rare earth magnet powder) X was mixed to 8 . As in Example 1, the sample was reduced to approximately 50 g, placed in a vacuum chamber, and heat-treated at a predetermined temperature and time while evacuating with a diffusion pump. At this time, the hydride is dehydrogenated and becomes an M element, M element alloy, or ML alloy alone. After the heat treatment, it was quenched by introducing high purity argon gas. This produced rare-earth alloy anisotropic magnet powder. The magnetic properties of the obtained rare earth alloy anisotropic magnet powder were measured. This is shown in Table 6. It can be seen that the coercive force tends to increase as the anisotropic magnetic field increases.
[0032]
Using the obtained magnet powder (No. 60 in Table 6), as in Example 1, 2 g of phenol resin was used as thermosetting resin with respect to 98 g of magnet powder, and a magnetic field of 2.5 T was used in the mold. The bonded magnet was obtained by compression molding with the action of. The comparative material is No. 1 in Table 4. 52. Using the obtained bonded magnet, coercive force at room temperature, 80 ° C and 120 ° C was measured by VSM and shown in Table 7.
[0033]
[Table 7]
[Brief description of the drawings]
FIG. 1 is a graph showing the effect of heat treatment temperature on the coercivity of a mixture of rare earth alloy anisotropic magnet powder and ML alloy (DyCo).
FIG. 2 is a diagram showing the influence of the average particle size of ML alloy (DyCo) on the coercive force of a mixture of rare earth alloy anisotropic magnet powder and ML alloy (DyCo).
FIG. 3 shows the effect of the at% ratio X of the total rare earth metal in the rare earth magnet powder and the total rare earth metal of the ML alloy on the maximum energy product of the mixture of the rare earth alloy anisotropic magnet powder and the ML alloy (DyCo). Is a diagram showing.
FIG. 4 shows the effect of the at% ratio X of the total rare earth metal in the rare earth magnet powder and the total rare earth metal of the ML alloy on the coercive force of the mixture of the rare earth alloy anisotropic magnet powder and the ML alloy (DyCo). It is a figure to show.
Claims (7)
該コーティング層によって該異方性希土類磁石粉末のＲの一部がＤｙまたはＴｂによって置換された拡散層が該異方性希土類磁石粉末の表面に形成されることを特徴とする耐熱希土類合金異方性磁石粉末。On the surface of an anisotropic rare earth magnet powder composed of a tetragonal structure R2Fe14B type compound (R is a rare earth element comprising one or more of rare earth elements including yttrium), one or more of Dy or Tb and 1 of Fe or Co A coating layer made of an alloy containing more than seeds
Heat rare earth alloy anisotropic diffusion layer part of R of the anisotropic rare earth magnet powder is replaced by Dy or Tb by the coating layer, characterized in Rukoto formed on the surface of the anisotropic rare earth magnet powder Magnet powder.
該混合工程後の混合物を真空中あるいは不活性ガス雰囲気中に熱処理温度Ｔ D を４００℃≦Ｔ D ≦高温水素処理温度Ｔ H ＋５０° C に保持する熱処理工程とを備え、
請求項１に記載の耐熱希土類合金異方性磁石粉末が得られることを特徴とする耐熱希土類合金異方性磁石粉末の製造方法。
Ｘ＝ｍ／(ｒ＋ｍ）×１００
ｍ：ＤｙまたはＴｂを含む粉末中におけるＤｙおよびＴｂの全ａｔ％
ｒ：異方性希土類磁石粉末中における希土類元素の全ａｔ％Tetragonal structure R2Fe14B type compound (R is a rare earth element consists of one or more of the rare earth elements including yttrium) showing the powder containing anisotropic rare earth magnet powder and Dy or Tb Ri which are high-temperature hydrogen annealing Tona below A mixing step in which X is mixed at a ratio of 0.03 <X <24;
A heat treatment step of maintaining the heat treatment temperature T D at 400 ° C. ≦ T D ≦ high temperature hydrogen treatment temperature T H + 50 ° C. in a vacuum or an inert gas atmosphere after the mixing step,
A heat-resistant rare earth alloy anisotropic magnet powder according to claim 1, wherein the heat-resistant rare earth alloy anisotropic magnet powder is obtained.
X = m / (r + m) × 100
m : total at% of Dy and Tb in the powder containing Dy or Tb
r : Total at% of rare earth element in anisotropic rare earth magnet powder
該混合工程後の混合物を真空中あるいは不活性ガス雰囲気中に熱処理温度ＴThe mixture after the mixing step is subjected to a heat treatment temperature T in a vacuum or in an inert gas atmosphere. DD を４００℃≦Ｔ400 ℃ ≦ T DD ≦高温水素処理温度Ｔ≦ High temperature hydrogen treatment temperature T HH ＋５０°+ 50 ° CC に保持する熱処理工程とを備え、Heat treatment step
請求項２に記載の耐熱希土類合金異方性磁石粉末が得られることを特徴とする耐熱希土類合金異方性磁石粉末の製造方法。A method for producing a heat-resistant rare earth alloy anisotropic magnet powder, characterized in that the heat-resistant rare earth alloy anisotropic magnet powder according to claim 2 is obtained.
Ｘ＝ｍ／X = m / (( ｒ＋ｍ）×１００r + m) × 100
ｍ：ＤｙまたはＴｂを含む粉末中におけるＤｙおよびＴｂの全ａｔ％m: Total at% of Dy and Tb in the powder containing Dy or Tb
ｒ：異方性希土類磁石粉末中における希土類元素の全ａｔ％r: Total at% of rare earth element in anisotropic rare earth magnet powder
求項３に記載の耐熱希土類合金異方性磁石粉末の製造方法。The method for producing a heat-resistant rare earth alloy anisotropic magnet powder according to claim 3, wherein the powder containing Dy or Tb is one or more hydride powders of Dy or Tb.
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| JP26414998A JP3865180B2 (en) | 1998-09-18 | 1998-09-18 | Heat-resistant rare earth alloy anisotropic magnet powder |
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| JP3452254B2 (en) * | 2000-09-20 | 2003-09-29 | 愛知製鋼株式会社 | Method for producing anisotropic magnet powder, raw material powder for anisotropic magnet powder, and bonded magnet |
| EP1330015A4 (en) * | 2000-10-25 | 2007-03-21 | Nec Tokin Corp | Magnetic core, coil component comprising it, and power source circuit |
| JP4828044B2 (en) * | 2001-05-31 | 2011-11-30 | Ｎｅｃトーキン株式会社 | Power circuit |
| CN101006534B (en) * | 2005-04-15 | 2011-04-27 | 日立金属株式会社 | Rare earth sintered magnet and process for producing the same |
| JP4742966B2 (en) * | 2006-04-19 | 2011-08-10 | 日立金属株式会社 | Method for producing R-Fe-B rare earth sintered magnet |
| JP5125818B2 (en) * | 2007-07-24 | 2013-01-23 | 日産自動車株式会社 | Magnetic compact and manufacturing method thereof |
| JP5417632B2 (en) * | 2008-03-18 | 2014-02-19 | 日東電工株式会社 | Permanent magnet and method for manufacturing permanent magnet |
| JP5381435B2 (en) * | 2009-07-14 | 2014-01-08 | 富士電機株式会社 | Method for producing magnet powder for permanent magnet, permanent magnet powder and permanent magnet |
| WO2011070827A1 (en) * | 2009-12-09 | 2011-06-16 | 愛知製鋼株式会社 | Rare earth anisotropic magnet and process for production thereof |
| CN107424694A (en) | 2009-12-09 | 2017-12-01 | 爱知制钢株式会社 | Rare-earth anisotropic magnetic iron powder and its manufacture method and binding magnet |
| WO2011145674A1 (en) * | 2010-05-20 | 2011-11-24 | 独立行政法人物質・材料研究機構 | Method for producing rare earth permanent magnets, and rare earth permanent magnets |
| US8480815B2 (en) * | 2011-01-14 | 2013-07-09 | GM Global Technology Operations LLC | Method of making Nd-Fe-B sintered magnets with Dy or Tb |
| KR101341344B1 (en) | 2012-02-08 | 2013-12-13 | 한양대학교 산학협력단 | R-Fe-B Sintered magnet with enhanced coercivity and fabrication method thereof |
| JP6819328B2 (en) * | 2017-02-03 | 2021-01-27 | 株式会社豊田中央研究所 | Magnetic powder and its manufacturing method |
| CN109087767A (en) * | 2018-08-08 | 2018-12-25 | 杭州电子科技大学 | A kind of crystal boundary spreads the neodymium iron boron magnetic body and preparation method thereof of nanoscale diffusate in situ |
| CN113936877A (en) * | 2020-06-29 | 2022-01-14 | 有研稀土新材料股份有限公司 | Modified sintered neodymium-iron-boron magnet and preparation method and application thereof |
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