JP4538959B2 - Electric Ni plating method for rare earth permanent magnet - Google Patents
Electric Ni plating method for rare earth permanent magnet Download PDFInfo
- Publication number
- JP4538959B2 JP4538959B2 JP2001013288A JP2001013288A JP4538959B2 JP 4538959 B2 JP4538959 B2 JP 4538959B2 JP 2001013288 A JP2001013288 A JP 2001013288A JP 2001013288 A JP2001013288 A JP 2001013288A JP 4538959 B2 JP4538959 B2 JP 4538959B2
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- Prior art keywords
- plating
- electric
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- plating film
- acid
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- 238000007747 plating Methods 0.000 title claims description 196
- 238000000034 method Methods 0.000 title claims description 36
- 229910052761 rare earth metal Inorganic materials 0.000 title claims description 18
- 150000002910 rare earth metals Chemical class 0.000 title claims description 17
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 37
- 239000004327 boric acid Substances 0.000 claims description 37
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 30
- 150000002500 ions Chemical class 0.000 claims description 26
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 22
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 15
- 239000006172 buffering agent Substances 0.000 claims description 12
- 239000000460 chlorine Substances 0.000 claims description 11
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 10
- 238000005868 electrolysis reaction Methods 0.000 claims description 8
- 238000009713 electroplating Methods 0.000 claims description 7
- 150000003839 salts Chemical class 0.000 claims description 6
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 claims description 5
- KDYFGRWQOYBRFD-UHFFFAOYSA-N Succinic acid Natural products OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 claims description 5
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 claims description 5
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 claims description 5
- 239000001630 malic acid Substances 0.000 claims description 5
- 235000011090 malic acid Nutrition 0.000 claims description 5
- PYRZPBDTPRQYKG-UHFFFAOYSA-N cyclopentene-1-carboxylic acid Chemical compound OC(=O)C1=CCCC1 PYRZPBDTPRQYKG-UHFFFAOYSA-N 0.000 claims description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 176
- 239000000243 solution Substances 0.000 description 63
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 18
- 238000011156 evaluation Methods 0.000 description 13
- 230000007797 corrosion Effects 0.000 description 11
- 238000005260 corrosion Methods 0.000 description 11
- 235000019270 ammonium chloride Nutrition 0.000 description 9
- 229960004106 citric acid Drugs 0.000 description 9
- 238000004070 electrodeposition Methods 0.000 description 8
- 239000000654 additive Substances 0.000 description 7
- 229910000008 nickel(II) carbonate Inorganic materials 0.000 description 7
- ZULUUIKRFGGGTL-UHFFFAOYSA-L nickel(ii) carbonate Chemical compound [Ni+2].[O-]C([O-])=O ZULUUIKRFGGGTL-UHFFFAOYSA-L 0.000 description 7
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 6
- 239000000872 buffer Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 6
- LAIZPRYFQUWUBN-UHFFFAOYSA-L nickel chloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].[Cl-].[Ni+2] LAIZPRYFQUWUBN-UHFFFAOYSA-L 0.000 description 6
- RRIWRJBSCGCBID-UHFFFAOYSA-L nickel sulfate hexahydrate Chemical compound O.O.O.O.O.O.[Ni+2].[O-]S([O-])(=O)=O RRIWRJBSCGCBID-UHFFFAOYSA-L 0.000 description 6
- 229940116202 nickel sulfate hexahydrate Drugs 0.000 description 6
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 5
- 229910052759 nickel Inorganic materials 0.000 description 5
- 229910017604 nitric acid Inorganic materials 0.000 description 5
- XNMQEEKYCVKGBD-UHFFFAOYSA-N 2-butyne Chemical compound CC#CC XNMQEEKYCVKGBD-UHFFFAOYSA-N 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- DLDJFQGPPSQZKI-UHFFFAOYSA-N but-2-yne-1,4-diol Chemical compound OCC#CCO DLDJFQGPPSQZKI-UHFFFAOYSA-N 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- -1 chlorine ions Chemical class 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- SRSXLGNVWSONIS-UHFFFAOYSA-N benzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC=C1 SRSXLGNVWSONIS-UHFFFAOYSA-N 0.000 description 2
- 229940092714 benzenesulfonic acid Drugs 0.000 description 2
- 230000003139 buffering effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- ZYGHJZDHTFUPRJ-UHFFFAOYSA-N coumarin Chemical compound C1=CC=C2OC(=O)C=CC2=C1 ZYGHJZDHTFUPRJ-UHFFFAOYSA-N 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- TVDSBUOJIPERQY-UHFFFAOYSA-N prop-2-yn-1-ol Chemical compound OCC#C TVDSBUOJIPERQY-UHFFFAOYSA-N 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 229910000722 Didymium Inorganic materials 0.000 description 1
- 241000224487 Didymium Species 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- 229910001122 Mischmetal Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 238000012669 compression test Methods 0.000 description 1
- 229960000956 coumarin Drugs 0.000 description 1
- 235000001671 coumarin Nutrition 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005347 demagnetization Effects 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 150000002009 diols Chemical class 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229920006332 epoxy adhesive Polymers 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910001172 neodymium magnet Inorganic materials 0.000 description 1
- 150000002815 nickel Chemical class 0.000 description 1
- 229940078494 nickel acetate Drugs 0.000 description 1
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 1
- 229940053662 nickel sulfate Drugs 0.000 description 1
- UQPSGBZICXWIAG-UHFFFAOYSA-L nickel(2+);dibromide;trihydrate Chemical compound O.O.O.Br[Ni]Br UQPSGBZICXWIAG-UHFFFAOYSA-L 0.000 description 1
- KERTUBUCQCSNJU-UHFFFAOYSA-L nickel(2+);disulfamate Chemical compound [Ni+2].NS([O-])(=O)=O.NS([O-])(=O)=O KERTUBUCQCSNJU-UHFFFAOYSA-L 0.000 description 1
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- 229960000999 sodium citrate dihydrate Drugs 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- HRXKRNGNAMMEHJ-UHFFFAOYSA-K trisodium citrate Chemical compound [Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O HRXKRNGNAMMEHJ-UHFFFAOYSA-K 0.000 description 1
- RHZZVWTVJHZKAH-UHFFFAOYSA-K trisodium;naphthalene-1,2,3-trisulfonate Chemical compound [Na+].[Na+].[Na+].C1=CC=C2C(S([O-])(=O)=O)=C(S([O-])(=O)=O)C(S(=O)(=O)[O-])=CC2=C1 RHZZVWTVJHZKAH-UHFFFAOYSA-K 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Electroplating And Plating Baths Therefor (AREA)
- Electroplating Methods And Accessories (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、新規な組成のＮｉめっき液を使用して希土類系磁石の表面に均一電着性や緻密性や外観などに優れたＮｉめっき被膜を形成するための電気Ｎｉめっき方法に関する。
【０００２】
【従来の技術】
Ｎｄ−Ｆｅ−Ｂ系永久磁石に代表されるＲ−Ｆｅ−Ｂ系永久磁石などの希土類系永久磁石は、高い磁気特性を有しているが、大気中で酸化腐食されやすい金属種（特にＲ）を含むので、表面処理を行わずに使用した場合には、わずかな酸やアルカリや水分などの影響によって表面から腐食が進行して錆が発生し、それに伴って、磁気特性の劣化やばらつきを招くことになる。さらに、磁気回路などの装置に組み込んだ磁石に錆が発生した場合、錆が飛散して周辺部品を汚染する恐れがある。従って、これらの問題点を回避するために、従来から、該磁石に要求される耐食性を付与すべく電気Ｎｉめっきにより、耐食性被膜としてのＮｉめっき被膜をその表面に形成することが行われている。
希土類系永久磁石の電気Ｎｉめっきにおいては、例えば、特開平６−１３２１８号公報に記載されているめっき液のように、ホウ酸を含んだめっき液が広く採用されている。ホウ酸含有Ｎｉめっき液は、ホウ酸が優れた緩衝作用を有しており、希土類系永久磁石のめっき処理に適したｐＨ（概ね４〜８）環境を容易に作り出すことができることや、該めっき液を使用して形成されるＮｉめっき被膜が均一電着性や緻密性や外観などに優れることから、希土類系永久磁石の表面にＮｉめっき被膜を形成するためのめっき液として最良とされており、また、電流効率や操業性に優れること、薬液コストが低いことといったような利点も有している。
【０００３】
【発明が解決しようとする課題】
ところで、ホウ酸含有Ｎｉめっき液において、ホウ酸の作用を如何なく発揮させるためには、一般的にはホウ酸をめっき液中に３０ｇ／ｌ程度含ませることが必要とされている。前記公報に記載されたＮｉめっき液はホウ酸の含有量が比較的少ないが、それでも実施例に記載されためっき液でホウ酸の含有量が最も少ないものでもその含有量は１５ｇ／ｌである。環境問題への対応が不可欠な近年においては、水質汚濁を防止するためにもめっき液の排水問題への対応が重要課題となっており、ホウ酸含有Ｎｉめっき液についても、環境に好ましいとはいえないホウ酸の含有量を低減化させる必要がある。
一方、希土類系永久磁石表面に直接Ｎｉめっき被膜を形成する場合、特に、バレル式電気めっきを行う場合、全ての磁石に均一に通電されるまでにＮｉが置換析出することがある。表面にＮｉが置換析出した磁石に電気Ｎｉめっきを行っても、形成されるＮｉめっき被膜は均一電着性に劣り、結果として磁石の耐食性に影響を及ぼすことになる。従って、Ｎｉめっき被膜形成の効率は維持しつつもめっき液に含まれるＮｉイオン濃度はできるだけ低減化させる必要がある。
そこで本発明は、新規な組成のＮｉめっき液を使用して希土類系磁石の表面に均一電着性や緻密性や外観などに優れたＮｉめっき被膜を形成するための電気Ｎｉめっき方法を提供することを目的とする。
【０００４】
【課題を解決するための手段】
本発明者らは、上記の点に鑑み種々の検討を行った結果、Ｎｉめっき液に含まれるＮｉイオン濃度と塩素イオン濃度の重量比、ホウ酸に代わる緩衝剤の使用とその含有量を調整することにより、Ｎｉめっき液中のホウ酸の含有量を低減させても、従来量のホウ酸を含有するＮｉめっき液を使用して形成されるＮｉめっき被膜が有する均一電着性や緻密性や外観などの優れた特性を維持したＮｉめっき被膜を形成することができることやＮｉの置換析出を抑制して均一電着性に優れたＮｉめっき被膜を形成することができることを知見した。
【０００５】
本発明は、上記の知見に基づいてなされたものであり、本発明の電気Ｎｉめっき方法は、請求項１記載の通り、希土類系永久磁石の電気Ｎｉめっき方法において、Ｎｉイオン濃度の塩素イオン濃度に対する重量比（Ｎｉ２＋／Ｃｌ−）が０．１９〜１１．４になるような含量でのＮｉイオンと塩素イオン（但しＮｉイオンは１５ｇ／ｌ〜８０ｇ／ｌ、塩素イオンは７ｇ／ｌ〜８０ｇ／ｌ）、緩衝剤としてコハク酸、マロン酸、クエン酸、リンゴ酸、酢酸およびこれらの塩から選ばれる少なくとも１種を０．０３ｍｏｌ／ｌ〜１．０ｍｏｌ／ｌ、ホウ酸を０〜１５ｇ／ｌ、含むめっき液を使用して磁石表面にＮｉめっき被膜を形成することを特徴とする。
また、請求項２記載の電気Ｎｉめっき方法は、請求項１記載の電気Ｎｉめっき方法において、前記めっき液がホウ酸を０〜１０ｇ／ｌ含むことを特徴とする。
また、請求項３記載の電気Ｎｉめっき方法は、請求項２記載の電気Ｎｉめっき方法において、磁石表面に多層めっき被膜層を形成するに際しての第２層目以降にＮｉめっき被膜を形成するための電気Ｎｉめっきであることを特徴とする。
また、請求項４記載の電気Ｎｉめっき方法は、請求項１記載の電気Ｎｉめっき方法において、磁石表面に直接Ｎｉめっき被膜を形成するに際しての前記めっき液のＮｉイオン濃度の塩素イオン濃度に対する重量比が０．１９〜４．０であることを特徴とする。
また、請求項５記載の電気Ｎｉめっき方法は、請求項１乃至４のいずれかに記載の電気Ｎｉめっき方法において、パルス電解を行いながら電気Ｎｉめっきを行うことを特徴とする。
また、請求項６記載の電気Ｎｉめっき方法は、請求項１乃至５のいずれかに記載の電気Ｎｉめっき方法において、希土類系永久磁石がＲ−Ｆｅ−Ｂ系永久磁石であることを特徴とする。
【０００６】
【発明の実施の形態】
本発明の電気Ｎｉめっき方法は、希土類系永久磁石の電気Ｎｉめっき方法において、Ｎｉイオン濃度の塩素イオン濃度に対する重量比（Ｎｉ２＋／Ｃｌ−）が０．１９〜１１．４になるような含量でのＮｉイオンと塩素イオン、緩衝剤としてコハク酸、マロン酸、クエン酸、リンゴ酸、酢酸およびこれらの塩から選ばれる少なくとも１種を０．０３ｍｏｌ／ｌ〜１．０ｍｏｌ／ｌ、ホウ酸を０〜１５ｇ／ｌ、含むめっき液を使用して磁石表面にＮｉめっき被膜を形成することを特徴とするものである。
【０００７】
本発明の電気Ｎｉめっき方法において使用されるＮｉめっき液には、Ｎｉイオン濃度の塩素イオン濃度に対する重量比（Ｎｉ２＋／Ｃｌ−）が０．１９〜１１．４になるようにＮｉイオンと塩素イオンを含ませる。Ｎｉイオン濃度の塩素イオン濃度に対する重量比が０．１９よりも小さい場合、磁石表面に塩素イオンが残留したり、形成されるＮｉめっき被膜の内部応力が高くなりすぎるなどの問題が生じる恐れがあり、１１．４よりも大きい場合、Ｎｉめっき液の電気伝導度に影響を及ぼす恐れがある。このような重量比に調整するためには、例えば、めっき液中にＮｉイオンを１５ｇ／ｌ〜８０ｇ／ｌ、塩素イオンを７ｇ／ｌ〜８０ｇ／ｌ含ませればよい。なお、Ｎｉイオンの供給源としては、硫酸ニッケル、塩化ニッケル、スルファミン酸ニッケル、臭化ニッケル、酢酸ニッケルなどがある。また、塩素イオンの供給源としては、前記の塩化ニッケルの他、塩化アンモニウムや塩化ナトリウムなどがある。
【０００８】
緩衝剤としてはコハク酸、マロン酸、クエン酸、リンゴ酸、酢酸およびこれらの塩から選ばれる少なくとも１種を０．０３ｍｏｌ／ｌ〜１．０ｍｏｌ／ｌ含ませる。これらの緩衝剤の含有量が０．０３ｍｏｌ／ｌよりも少ない場合、緩衝作用が十分に発揮されない恐れがあり、１．０ｍｏｌ／ｌよりも多い場合、Ｎｉめっき液の長期安定性に影響を及ぼす恐れがある。磁石表面に直接Ｎｉめっき被膜を形成する場合には緩衝剤は０．２ｍｏｌ／ｌ〜１．０ｍｏｌ／ｌ含ませることがＮｉの置換析出を極力抑制する観点から望ましい。緩衝剤の中ではクエン酸およびその塩が形成されるＮｉめっき被膜の緻密性の点において望ましい。なお、コハク酸、マロン酸、クエン酸、リンゴ酸、酢酸の塩としては、ナトリウム塩、カリウム塩、アンモニウム塩、ニッケル塩などがある。
【０００９】
Ｎｉめっき液に含まれるＮｉイオン濃度と塩素イオン濃度の重量比、ホウ酸に代わる緩衝剤の使用とその含有量を上記のように調整することにより、Ｎｉめっき液中のホウ酸の含有量を１５ｇ／ｌ以下としても、従来量のホウ酸を含有するめっき液を使用して形成されるＮｉめっき被膜が有する均一電着性や緻密性や外観などの優れた特性を維持したＮｉめっき被膜を形成することができる。
【００１０】
希土類系永久磁石表面に直接Ｎｉめっき被膜を形成する場合、高い電流効率を確保して迅速にＮｉめっき被膜を形成することが肝要であることから、Ｎｉめっき液中にはホウ酸を最大１５ｇ／ｌの範囲内で含ませることが望ましいが、本発明の電気Ｎｉめっき方法において、特に、Ｎｉめっき液中のホウ酸の含有量が１０ｇ／ｌ以下の場合、即ち、究極的にはめっき液中にホウ酸を含ませない場合でも優れた特性を有するＮｉめっき被膜を形成することができることは、めっき液の排水問題への対応において非常に望ましいことであり、磁石表面に多層めっき被膜層を形成するに際しての第２層目以降にＮｉめっき被膜を形成する場合に効果を発揮する。
【００１１】
また、希土類系永久磁石表面に直接Ｎｉめっき被膜を形成するに際してのＮｉめっき液のＮｉイオン濃度の塩素イオン濃度に対する重量比を０．１９〜４．０に調整することにより、Ｎｉの置換析出を抑制して均一電着性に優れたＮｉめっき被膜を形成することができる。
【００１２】
Ｎｉめっき液のｐＨは４〜８に調整することが望ましい。ｐＨ調整剤は、例えば、炭酸ニッケルや硫酸など、めっき液の成分に応じた公知のものを使用すればよい。また、Ｎｉめっき液には優れた外観を有するＮｉめっき被膜を形成するためや、電子部品への適用時に要求される清浄性や接着性などを満たすために、ラウリル硫酸ナトリウム、２−ブチン１，４−ジオール、ベンゼンスルホン酸、プロパギルアルコール、クマリンなどの光沢剤のような各種自体公知の有機添加剤や無機添加剤を添加してもよい。また、導電補助剤として、硫酸ナトリウムや塩化アンモニウムなどを添加してもよい。
【００１３】
本発明においては、電気Ｎｉめっきを行うに際してのめっき浴の液温は３０℃〜７０℃に調整することが望ましい。
【００１４】
本発明においては、パルス電解を行いながら電気Ｎｉめっきを行うことが望ましい。本発明におけるＮｉめっき液を使用してパルス電解を行いながら電気Ｎｉめっきを行うことにより、金属結晶の微細緻密化や形成されるＮｉめっき被膜の密着性向上などの効果が得られる。パルス電解条件としては、パルス周期が２ｍｓｅｃ〜１００ｍｓｅｃ、ＴＯＮが１ｍｓｅｃ〜９５ｍｓｅｃ、ＴＯＦＦが１ｍｓｅｃ〜９５ｍｓｅｃ、ピーク電流密度Ｉｐが０．２Ａ／ｄｍ２〜１００Ａ／ｄｍ２なる条件が挙げられる。
【００１５】
本発明の電気Ｎｉめっき方法で形成されるＮｉめっき被膜の膜厚は、希土類系永久磁石表面にこのＮｉめっき被膜のみを形成する場合は５μｍ〜３０μｍが望ましく、磁石表面に多層めっき被膜層を形成するに際しての第１層目にこのＮｉめっき被膜を形成する場合は０．２μｍ〜１０μｍが望ましく、第２層目以降にこのＮｉめっき被膜を形成する場合は１μｍ〜３０μｍが望ましい。磁石表面に多層めっき被膜層を形成するに際しての第２層目以降にこのＮｉめっき被膜を形成する場合、第１層目にはＮｉめっき被膜の他、Ｃｕめっき被膜やＳｎめっき被膜やＺｎめっき被膜などの異なる金属めっき被膜を公知の成膜法にて形成してもよい。また、本発明の電気Ｎｉめっき方法で形成されるＮｉめっき被膜の上に、異なる金属めっき被膜を形成してもよいし、化成処理被膜などの別種の被膜を形成してもよい。
【００１６】
本発明に適用される希土類系永久磁石の内、Ｒ−Ｆｅ−Ｂ系永久磁石における希土類元素（Ｒ）は、Ｎｄ、Ｐｒ、Ｄｙ、Ｈｏ、Ｔｂ、Ｓｍのうち少なくとも１種、あるいはさらに、Ｌａ、Ｃｅ、Ｇｄ、Ｅｒ、Ｅｕ、Ｔｍ、Ｙｂ、Ｌｕ、Ｙのうち少なくとも１種を含むものが望ましい。
また、通常はＲのうち１種をもって足りるが、実用上は２種以上の混合物（ミッシュメタルやジジムなど）を入手上の便宜などの理由によって使用することもできる。
さらに、Ａｌ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｂｉ、Ｎｂ、Ｔａ、Ｍｏ、Ｗ、Ｓｂ、Ｇｅ、Ｓｎ、Ｚｒ、Ｎｉ、Ｓｉ、Ｚｎ、Ｈｆ、Ｇａのうち少なくとも１種を添加することで、保磁力や減磁曲線の角型性の改善、製造性の改善、低価格化を図ることが可能となる。また、Ｆｅの一部をＣｏで置換することによって、得られる磁石の磁気特性を損なうことなしに温度特性を改善することができる。
【００１７】
【実施例】
本発明を以下の実施例によってさらに詳細に説明するが、本発明は以下の記載に何ら限定されるものではない。
【００１８】
実施例１：
粉末冶金法により作製した１５Ｎｄ−１Ｄｙ−７Ｂ−７７Ｆｅ（原子％）の組成をもつ焼結体をアルゴン雰囲気中６００℃で２時間時効処理を施し、厚さ３ｍｍ、幅１２ｍｍ、長さ３０ｍｍの平板状に加工し、さらにバレル面取り加工を行って得られた焼結磁石を希釈硝酸で酸洗清浄化した。
この磁石に対し、硫酸ニッケル・６水和物と塩化ニッケル・６水和物と塩化アンモニウム（めっき液７についてはさらに塩化ナトリウムを使用）で表１に示した各種の濃度に調整したＮｉイオンと塩素イオン、緩衝剤としてクエン酸ナトリウム・２水和物１４７ｇ／ｌ（０．５ｍｏｌ／ｌ）、ホウ酸８ｇ／ｌ、添加剤としてラウリル硫酸ナトリウム０．０２ｇ／ｌと２−ブチン１，４−ジオール０．５ｇ／ｌを含み、ｐＨを塩基性炭酸ニッケルを添加することにより５に調整した７種類のＮｉめっき液を使用し、めっき浴の液温５０℃、電流密度２Ａ／ｄｍ２、陽極としてＮｉ板という電気Ｎｉめっき条件にて、膜厚が１０μｍのＮｉめっき被膜を磁石表面に形成した。形成されたＮｉめっき被膜の性能を表１に示す。
【００１９】
表１における被膜健全性の評価はめっき被膜の緻密性及び耐食性促進評価（発色反応試験）により行った。評価方法を簡単に説明すると以下の通りである。フェリシアン化カリウム３ｇ／ｌ、エタノール１００ｍｌ／ｌおよび塩酸にてｐＨ２に調整した試験液にめっき磁石サンプルを常温で浸漬して６０分間観察した。磁石素材に腐食が至ったり被膜欠陥（ピンホールなど）が存在する場合には青色斑点が発生するので、３０分浸漬後も青色斑点の発生がない場合は◎、浸漬後２０〜３０分で青色斑点が発生した場合は○、浸漬後１０分〜２０分で青色斑点が発生した場合は△、浸漬後１０分未満で青色斑点が発生した場合は×と評価した。
【００２０】
表１におけるめっき付廻り性の評価は同一めっき磁石サンプルの平面部の１０箇所観察によるめっき付着量（膜厚）のバラツキについて、バラツキが±１０％以内の場合は○、バラツキが±１０％〜２０％の場合は△、バラツキが±２０％を超える場合は×と評価することで行った。
【００２１】
【表１】
表１から明らかなように、Ｎｉめっき液におけるＮｉイオン濃度の塩素イオン濃度に対する重量比（Ｎｉ２＋／Ｃｌ−）を所定の重量比に調整することで、ホウ酸の含有量を従来のホウ酸含Ｎｉめっき液の含有量より大幅に低減させても優れた特性のＮｉめっき被膜を形成することができることがわかった（めっき液２〜めっき液６）。
【００２３】
実施例２：
実施例１と同様の方法で得られた焼結磁石を希釈硝酸で酸洗清浄化した。この磁石に対し、硫酸ニッケル・６水和物と塩化ニッケル・６水和物と塩化アンモニウムで表２に示した各種の濃度に調整したＮｉイオンと塩素イオン、表２に示した各種の濃度に調整した緩衝剤、ホウ酸８ｇ／ｌ、添加剤としてラウリル硫酸ナトリウム０．０２ｇ／ｌと２−ブチン１，４−ジオール０．５ｇ／ｌと１，３，６ナフタレントリスルホン酸ナトリウム２．０ｇ／ｌを含み、ｐＨを塩基性炭酸ニッケルを添加することにより６に調整した１１種類のＮｉめっき液を使用し、めっき浴の液温５０℃、電流密度３Ａ／ｄｍ２、陽極としてＮｉ板という電気Ｎｉめっき条件にて、膜厚が１０μｍのＮｉめっき被膜を磁石表面に形成した。形成されたＮｉめっき被膜の性能を表２に示す。
【００２４】
表２における被膜健全性の評価は実施例１と同様にして行った。耐食性の評価はプレッシャークッカー試験により行った。評価方法を簡単に説明すると以下の通りである。めっき磁石サンプルを１２５℃、８５％ＲＨ、２気圧の環境下に２００時間放置し、赤錆やフクレが発生しない場合は○、わずかな赤錆やフクレが発生した場合は△、赤錆やフクレが多数発生した場合は×と評価した。
【００２５】
【表２】
表２から明らかなように、ホウ酸に代わるクエン酸などの緩衝剤の含有量を０．０３ｍｏｌ／ｌ以上に調整することで、ホウ酸の含有量を従来のホウ酸含Ｎｉめっき液の含有量より大幅に低減させても優れた特性のＮｉめっき被膜を形成することができることがわかった（めっき液２〜めっき液１１）。
【００２７】
実施例３：
実施例１と同様の方法で得られた焼結磁石を希釈硝酸で酸洗清浄化した。この磁石に対し、実施例１のＮｉめっき液４を使用し、実施例１と同様の電気Ｎｉめっき条件にて、膜厚が３μｍのＮｉめっき被膜を磁石表面に形成した。
次に、硫酸ニッケル・６水和物と塩化ニッケル・６水和物と塩化アンモニウムで表３に示した各種の濃度に調整したＮｉイオンと塩素イオン、表３に示した各種の濃度に調整した緩衝剤、添加剤としてラウリル硫酸ナトリウム０．０２ｇ／ｌと２−ブチン１，４−ジオール０．５ｇ／ｌを含み、ｐＨを塩基性炭酸ニッケルを添加することにより５に調整した５種類のＮｉめっき液を使用し、実施例１と同様の電気Ｎｉめっき条件にて、第２層Ｎｉめっき被膜として膜厚が１５μｍの被膜を第１層Ｎｉめっき被膜表面に形成した。形成されたＮｉめっき被膜の性能を表３に示す。
【００２８】
表３における被膜健全性の評価は実施例１と同様にして行った。耐食性の評価は実施例２と同様にして行った。めっき密着性の評価はめっき磁石サンプルにエポキシ系樹脂（ＳＷ２２１４：住友３Ｍ製の熱硬化型エポキシ系接着剤で塗布接着後１２０℃、６０分で加熱硬化）を塗布して鋼製治具と接着した後、１８０度剪断圧縮試験にて破壊強度（めっき剥離強度）を測定し、接着強度が４００ｋｇ／ｃｍ２以上の場合は○、接着強度が３００ｋｇ／ｃｍ２〜４００ｋｇ／ｃｍ２の場合は△、接着強度が３００ｋｇ／ｃｍ２未満の場合は×と評価することで行った。
【００２９】
【表３】
表３から明らかなように、Ｎｉめっき液にホウ酸を含ませなくても、Ｎｉめっき液におけるＮｉイオン濃度の塩素イオン濃度に対する重量比（Ｎｉ２＋／Ｃｌ−）を所定の重量比に調整し、ホウ酸に代わるクエン酸などの緩衝剤の含有量を調整することで、優れた特性のＮｉめっき被膜を形成することができることがわかった（めっき液１〜めっき液４）。
【００３１】
実施例４：
実施例１と同様の方法で得られた焼結磁石を希釈硝酸で酸洗清浄化した。この磁石に対し、自体公知のアルカリ浴Ｃｕめっきを行って膜厚が３μｍのＣｕめっき被膜を磁石表面に形成した。
次に、硫酸ニッケル・６水和物と塩化ニッケル・６水和物と塩化アンモニウムで表４に示した各種の濃度に調整したＮｉイオンと塩素イオン、表４に示した各種の濃度に調整した緩衝剤、ホウ酸８ｇ／ｌ、添加剤としてラウリル硫酸ナトリウム０．０２ｇ／ｌと２−ブチン１，４−ジオール０．５ｇ／ｌを含み、ｐＨを塩基性炭酸ニッケルを添加することにより４に調整した５種類のＮｉめっき液を使用し、実施例１と同様の電気Ｎｉめっき条件にて、第２層Ｎｉめっき被膜として膜厚が１０μｍの被膜を第１層Ｃｕめっき被膜表面に形成した。
最後に、硫酸ニッケル・６水和物２００ｇ／ｌ、塩化ニッケル・６水和物４０ｇ／ｌ、塩化アンモニウム１０ｇ／ｌ（Ｎｉイオン濃度の塩素イオン濃度に対する重量比は４．５）、クエン酸２アンモニウム４５ｇ／ｌ（０．２ｍｏｌ／ｌ）、添加剤としてベンゼンスルホン酸１ｇ／ｌとプロパギルアルコール０．５ｇ／ｌを含み、ｐＨを塩基性炭酸ニッケルを添加することにより４に調整したＮｉめっき液を使用し、めっき浴の液温５０℃、電流密度３Ａ／ｄｍ２、陽極としてＮｉ板という電気Ｎｉめっき条件にて、第３層Ｎｉめっき被膜として膜厚が２μｍのＮｉめっき被膜を第２層Ｎｉめっき被膜表面に形成した。形成されたＮｉめっき被膜の性能を表４に示す。なお、表４における被膜健全性の評価は実施例１と同様にして行った。耐食性の評価は実施例２と同様にして行った。
【００３２】
【表４】
表４から明らかなように、Ｎｉめっき液におけるＮｉイオン濃度の塩素イオン濃度に対する重量比（Ｎｉ２＋／Ｃｌ−）を所定の重量比に調整し、ホウ酸に代わるクエン酸などの緩衝剤の含有量を調整することで、優れた特性のＮｉめっき被膜を形成することができることがわかった（めっき液２〜めっき液５）。
【００３４】
実施例５：
実施例１と同様の方法で得られた焼結磁石を希釈硝酸で酸洗清浄化した。この磁石に対し、硫酸ニッケル・６水和物と塩化ニッケル・６水和物と塩化アンモニウムで表５に示した各種の濃度に調整したＮｉイオンと塩素イオン、緩衝剤としてクエン酸ナトリウム・２水和物１４７ｇ／ｌ（０．５ｍｏｌ／ｌ）、ホウ酸８ｇ／ｌ、添加剤としてラウリル硫酸ナトリウム０．０２ｇ／ｌと２−ブチン１，４−ジオール０．５ｇ／ｌを含み、ｐＨを塩基性炭酸ニッケルを添加することにより５に調整した各種のＮｉめっき液を使用し、実施例１と同様の電気Ｎｉめっき条件のもと、各種のパルス電解条件（パルス周期ＴとＴＯＮとＴＯＦＦ）、ピーク電流密度Ｉｐ＝１０Ａ／ｄｍ２にてパルス電解を行いながら、膜厚が３μｍのＮｉめっき被膜を磁石表面に形成した。
次に、実施例４の第３層Ｎｉめっき被膜を形成するためのＮｉめっき液を使用し、実施例４と同様の電気Ｎｉめっき条件にて、第２層Ｎｉめっき被膜として膜厚が５μｍの被膜を第１層Ｎｉめっき被膜表面に形成した。形成されたＮｉめっき被膜の性能を表５に示す。なお、表５における被膜健全性の評価は実施例１と同様にして行った。耐食性の評価は実施例２と同様にして行った。めっき密着性の評価は実施例３と同様にして行った。
【００３５】
【表５】
表５から明らかなように、パルス電解を行いながら電気Ｎｉめっきを行うことにより、高電流密度（短時間）での電気Ｎｉめっきが可能となり、高い耐食性を有するＮｉめっき被膜を形成することができ、Ｎｉめっき被膜の膜厚の薄膜化、ひいては寸法精度の向上を図ることができることがわかった（めっき液１〜めっき液４）。
【００３７】
【発明の効果】
本発明の電気Ｎｉめっき方法によれば、Ｎｉめっき液に含まれるＮｉイオン濃度と塩素イオン濃度の重量比、ホウ酸に代わる緩衝剤の使用とその含有量を調整することにより、Ｎｉめっき液中のホウ酸の含有量を低減させても、従来量のホウ酸を含有するＮｉめっき液を使用して形成されるＮｉめっき被膜が有する均一電着性や緻密性や外観などの優れた特性を維持したＮｉめっき被膜を形成することができる。また、Ｎｉの置換析出を抑制して均一電着性に優れたＮｉめっき被膜を形成することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric Ni plating method for forming a Ni plating film excellent in uniform electrodeposition, denseness, appearance and the like on the surface of a rare earth magnet by using a Ni plating solution having a novel composition.
[0002]
[Prior art]
Rare earth permanent magnets such as R-Fe-B permanent magnets typified by Nd-Fe-B permanent magnets have high magnetic properties, but are metal species that are susceptible to oxidative corrosion in the atmosphere (particularly R ), When used without surface treatment, corrosion progresses from the surface due to the influence of slight acid, alkali, moisture, etc., and rust is generated. Will be invited. Furthermore, when rust is generated in a magnet incorporated in a device such as a magnetic circuit, the rust may be scattered and contaminate peripheral components. Therefore, in order to avoid these problems, conventionally, a Ni plating film as a corrosion resistant film is formed on the surface of the magnet by electro Ni plating so as to give the magnet the corrosion resistance required. .
In electric Ni plating of rare earth-based permanent magnets, for example, a plating solution containing boric acid is widely adopted as a plating solution described in JP-A-6-13218. The boric acid-containing Ni plating solution has an excellent buffering action, and can easily create a pH (approximately 4 to 8) environment suitable for rare earth permanent magnet plating, Ni plating film formed by using this solution is excellent in throwing power, denseness, and appearance. Therefore, it is the best plating solution for forming Ni plating film on the surface of rare earth permanent magnets. Also, it has advantages such as excellent current efficiency and operability and low chemical cost.
[0003]
[Problems to be solved by the invention]
By the way, in order to make the boric acid-containing Ni plating solution exhibit the action of boric acid, it is generally required to contain boric acid in the plating solution at about 30 g / l. Although the Ni plating solution described in the above publication has a relatively low content of boric acid, the content of the plating solution described in the examples with the lowest boric acid content is still 15 g / l. . In recent years, when dealing with environmental problems is indispensable, it is important to deal with the problem of drainage of the plating solution in order to prevent water pollution, and the boric acid-containing Ni plating solution is also favorable for the environment. It is necessary to reduce the content of boric acid that cannot be said.
On the other hand, when the Ni plating film is directly formed on the surface of the rare earth permanent magnet, particularly when barrel type electroplating is performed, Ni may be deposited by substitution until all magnets are uniformly energized. Even if electro Ni plating is performed on a magnet having Ni deposited on the surface, the formed Ni plating film is inferior in throwing power, and as a result, the corrosion resistance of the magnet is affected. Therefore, it is necessary to reduce the Ni ion concentration contained in the plating solution as much as possible while maintaining the efficiency of forming the Ni plating film.
Therefore, the present invention provides an electric Ni plating method for forming a Ni plating film excellent in uniform electrodeposition, denseness and appearance on the surface of a rare earth magnet by using a Ni plating solution having a novel composition. For the purpose.
[0004]
[Means for Solving the Problems]
As a result of various studies in view of the above points, the present inventors have adjusted the weight ratio between the Ni ion concentration and the chlorine ion concentration contained in the Ni plating solution, the use of a buffering agent instead of boric acid, and its content. Even if the content of boric acid in the Ni plating solution is reduced, the Ni plating film formed using the Ni plating solution containing the conventional amount of boric acid has uniform electrodeposition and denseness The present inventors have found that a Ni plating film having excellent properties such as the appearance and appearance can be formed, and that a Ni plating film having excellent uniform electrodeposition can be formed by suppressing substitutional deposition of Ni.
[0005]
The present invention has been made on the basis of the above knowledge, and the electric Ni plating method of the present invention is the method of claim 1, wherein the electric Ni plating method for rare earth permanent magnets is a chloride ion concentration of Ni ion concentration. Ni ion and chlorine ion in a content such that the weight ratio (Ni 2+ / Cl − ) is 0.19 to 11.4 (wherein Ni ion is 15 g / l to 80 g / l, chlorine ion is 7 g / l to 80 g / l) , 0.03 mol / l to 1.0 mol / l of at least one selected from succinic acid, malonic acid, citric acid, malic acid, acetic acid and salts thereof as buffers, and 0 to 15 g of boric acid A nickel plating film is formed on the surface of the magnet using a plating solution containing / l .
Also, electrical Ni plating method of claim 2, in Ni electroplating method according to claim 1, wherein the plating solution is characterized by containing boric acid 0 to 10 g / l.
Further, Ni electroplating method according to claim 3, wherein, in the Ni electroplating method according to claim 2, wherein, for forming the Ni plating film for the second layer and subsequent in forming a multi-layer plating coat layer on the magnet surface It is an electric Ni plating.
The electric Ni plating method according to claim 4 is the electric Ni plating method according to claim 1, wherein the weight ratio of the Ni ion concentration of the plating solution to the chlorine ion concentration when the Ni plating film is directly formed on the magnet surface. Is 0.19 to 4.0.
An electric Ni plating method according to claim 5 is the electric Ni plating method according to any one of claims 1 to 4 , wherein the electric Ni plating is performed while performing pulse electrolysis.
The electric Ni plating method according to claim 6 is the electric Ni plating method according to any one of claims 1 to 5 , wherein the rare earth permanent magnet is an R-Fe-B permanent magnet. .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The electric Ni plating method of the present invention is such that the weight ratio of Ni ion concentration to chlorine ion concentration (Ni 2+ / Cl − ) is 0.19 to 11.4 in the electric Ni plating method for rare earth permanent magnets. And at least one selected from succinic acid, malonic acid, citric acid, malic acid, acetic acid and salts thereof as a buffering agent at 0.03 mol / l to 1.0 mol / l, boric acid A nickel plating film is formed on the magnet surface using a plating solution containing 0 to 15 g / l.
[0007]
The Ni plating solution used in the electric Ni plating method of the present invention includes Ni ions and chlorine so that the weight ratio of Ni ion concentration to chlorine ion concentration (Ni 2+ / Cl − ) is 0.19 to 11.4. Include ions. If the weight ratio of the Ni ion concentration to the chlorine ion concentration is less than 0.19, there may be problems such as chlorine ions remaining on the magnet surface or the internal stress of the Ni plating film being formed becomes too high. If it is greater than 11.4, the electrical conductivity of the Ni plating solution may be affected. In order to adjust the weight ratio, for example, the plating solution may contain 15 g / l to 80 g / l of Ni ions and 7 g / l to 80 g / l of chlorine ions. Ni ion supply sources include nickel sulfate, nickel chloride, nickel sulfamate, nickel bromide, and nickel acetate. In addition to the above nickel chloride, the supply source of chloride ions includes ammonium chloride and sodium chloride.
[0008]
The buffering agent contains 0.03 mol / l to 1.0 mol / l of at least one selected from succinic acid, malonic acid, citric acid, malic acid, acetic acid and salts thereof. When the content of these buffering agents is less than 0.03 mol / l, the buffering action may not be sufficiently exerted. When the content is more than 1.0 mol / l, the long-term stability of the Ni plating solution is affected. There is a fear. When the Ni plating film is directly formed on the magnet surface, it is desirable that the buffering agent is contained in an amount of 0.2 mol / l to 1.0 mol / l from the viewpoint of suppressing Ni substitutional precipitation as much as possible. Among the buffering agents, it is desirable in terms of the denseness of the Ni plating film on which citric acid and its salt are formed. Examples of salts of succinic acid, malonic acid, citric acid, malic acid, and acetic acid include sodium salt, potassium salt, ammonium salt, and nickel salt.
[0009]
By adjusting the weight ratio between the Ni ion concentration and the chloride ion concentration contained in the Ni plating solution, the use of a buffering agent instead of boric acid and the content thereof as described above, the boric acid content in the Ni plating solution can be adjusted. A Ni plating film that maintains excellent properties such as uniform electrodeposition, denseness, and appearance of a Ni plating film formed using a plating solution containing a conventional amount of boric acid, even if it is 15 g / l or less. Can be formed.
[0010]
When forming a Ni plating film directly on the surface of a rare earth-based permanent magnet, it is important to form a Ni plating film quickly while ensuring high current efficiency. In the electric Ni plating method of the present invention, in particular, when the content of boric acid in the Ni plating solution is 10 g / l or less, that is, ultimately in the plating solution. It is very desirable to be able to form a Ni plating film with excellent characteristics even when boric acid is not included in the solution, in order to cope with the drainage problem of the plating solution, and to form a multilayer plating film layer on the magnet surface This is effective when a Ni plating film is formed on the second and subsequent layers.
[0011]
In addition, by adjusting the weight ratio of the Ni ion concentration of the Ni plating solution to the chlorine ion concentration in forming the Ni plating film directly on the surface of the rare earth-based permanent magnet to 0.19 to 4.0, Ni substitutional precipitation is achieved. It can suppress and can form the Ni plating film excellent in the uniform electrodeposition property.
[0012]
It is desirable to adjust the pH of the Ni plating solution to 4-8. As the pH adjuster, for example, a known one corresponding to the component of the plating solution such as nickel carbonate or sulfuric acid may be used. Further, in order to form a Ni plating film having an excellent appearance in the Ni plating solution, and to satisfy the cleanliness and adhesion required when applied to electronic components, sodium lauryl sulfate, 2-butyne 1, Various organic and inorganic additives known per se such as brighteners such as 4-diol, benzenesulfonic acid, propargyl alcohol, and coumarin may be added. Moreover, you may add sodium sulfate, ammonium chloride, etc. as a conductive support agent.
[0013]
In the present invention, it is desirable to adjust the temperature of the plating bath to 30 ° C. to 70 ° C. when performing electro Ni plating.
[0014]
In the present invention, it is desirable to perform electro Ni plating while performing pulse electrolysis. By performing electric Ni plating while performing pulse electrolysis using the Ni plating solution in the present invention, effects such as fine densification of metal crystals and improved adhesion of the formed Ni plating film can be obtained. Examples of the pulse electrolysis conditions include a pulse cycle of 2 msec to 100 msec, T ON of 1 msec to 95 msec, T OFF of 1 msec to 95 msec, and a peak current density I p of 0.2 A / dm 2 to 100 A / dm 2 .
[0015]
The film thickness of the Ni plating film formed by the electric Ni plating method of the present invention is preferably 5 to 30 μm when only this Ni plating film is formed on the surface of the rare earth permanent magnet, and a multilayer plating film layer is formed on the magnet surface. When forming the Ni plating film on the first layer, the thickness is preferably 0.2 μm to 10 μm, and when forming the Ni plating film on the second layer and thereafter, the thickness is preferably 1 μm to 30 μm. When this Ni plating film is formed after the second layer when the multilayer plating film layer is formed on the magnet surface, the first layer, in addition to the Ni plating film, the Cu plating film, the Sn plating film or the Zn plating film Different metal plating films such as may be formed by a known film forming method. Moreover, a different metal plating film may be formed on the Ni plating film formed by the electric Ni plating method of the present invention, or another type of film such as a chemical conversion treatment film may be formed.
[0016]
Among the rare earth permanent magnets applied to the present invention, the rare earth element (R) in the R—Fe—B permanent magnet is at least one of Nd, Pr, Dy, Ho, Tb, Sm, or La , Ce, Gd, Er, Eu, Tm, Yb, Lu, and Y are preferable.
Usually, one type of R is sufficient, but in practice, a mixture of two or more types (such as misch metal and didymium) may be used for reasons of convenience.
Furthermore, by adding at least one of Al, Ti, V, Cr, Mn, Bi, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr, Ni, Si, Zn, Hf, and Ga, It becomes possible to improve the squareness of the coercive force and the demagnetization curve, improve the manufacturability, and reduce the price. Further, by replacing part of Fe with Co, the temperature characteristics can be improved without impairing the magnetic characteristics of the obtained magnet.
[0017]
【Example】
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following description.
[0018]
Example 1:
A sintered body having a composition of 15Nd-1Dy-7B-77Fe (atomic%) prepared by powder metallurgy is subjected to aging treatment at 600 ° C. for 2 hours in an argon atmosphere, and a flat plate having a thickness of 3 mm, a width of 12 mm, and a length of 30 mm. Then, the sintered magnet obtained by further chamfering the barrel was pickled and cleaned with diluted nitric acid.
To this magnet, Ni ions adjusted to various concentrations shown in Table 1 with nickel sulfate hexahydrate, nickel chloride hexahydrate and ammonium chloride (sodium chloride is used for the plating solution 7) Chloride ion, sodium citrate dihydrate 147 g / l (0.5 mol / l) as buffer, boric acid 8 g / l, additive sodium lauryl sulfate 0.02 g / l and 2-butyne 1,4- Seven kinds of Ni plating solutions containing 0.5 g / l of diol and adjusted to pH 5 by adding basic nickel carbonate were used, the temperature of the plating bath was 50 ° C., the current density was 2 A / dm 2 , the anode A Ni plating film having a film thickness of 10 μm was formed on the magnet surface under the electric Ni plating condition of Ni plate. Table 1 shows the performance of the formed Ni plating film.
[0019]
Evaluation of film soundness in Table 1 was performed by evaluation of denseness and corrosion resistance of the plating film (coloring reaction test). The evaluation method is briefly described as follows. A plated magnet sample was immersed in a test solution adjusted to pH 2 with potassium ferricyanide 3 g / l, ethanol 100 ml / l and hydrochloric acid, and observed for 60 minutes. Blue spots occur when the magnet material is corroded or has film defects (pinholes, etc.). If there is no blue spots after immersion for 30 minutes, blue, 20-30 minutes after immersion. When the spot was generated, it was evaluated as ○, when the blue spot was generated 10 minutes to 20 minutes after immersion, Δ, and when the blue spot was generated less than 10 minutes after immersion, it was evaluated as ×.
[0020]
The evaluation of the plating coverage in Table 1 is about the variation of the coating adhesion amount (film thickness) by observing the flat part of the same plated magnet sample at 10 points. When the variation is within ± 10%, the variation is ± 10%. When 20%, the evaluation was Δ, and when the variation exceeded ± 20%, the evaluation was ×.
[0021]
[Table 1]
As apparent from Table 1, the boric acid content is adjusted to the conventional boric acid by adjusting the weight ratio of Ni ion concentration to the chloride ion concentration (Ni 2+ / Cl − ) in the Ni plating solution to a predetermined weight ratio. It has been found that even if the content of the Ni-containing plating solution is significantly reduced, a Ni plating film having excellent characteristics can be formed (plating solution 2 to plating solution 6).
[0023]
Example 2:
The sintered magnet obtained by the same method as in Example 1 was pickled and cleaned with diluted nitric acid. For this magnet, Ni ions and chloride ions adjusted to various concentrations shown in Table 2 with nickel sulfate hexahydrate, nickel chloride hexahydrate and ammonium chloride, and various concentrations shown in Table 2 Adjusted buffer, boric acid 8g / l, additive sodium lauryl sulfate 0.02g / l, 2-butyne 1,4-diol 0.5g / l, 1,3,6 sodium naphthalene trisulfonate 2.0g 11 kinds of Ni plating solution containing pH / l and adjusted to pH 6 by adding basic nickel carbonate, the temperature of the plating bath is 50 ° C., the current density is 3 A / dm 2 , and the Ni plate is used as the anode. A Ni plating film having a thickness of 10 μm was formed on the magnet surface under the electric Ni plating conditions. The performance of the formed Ni plating film is shown in Table 2.
[0024]
Evaluation of film soundness in Table 2 was carried out in the same manner as in Example 1. The corrosion resistance was evaluated by a pressure cooker test. The evaluation method is briefly described as follows. If the plated magnet sample is left in an environment of 125 ° C, 85% RH and 2 atm for 200 hours, no red rust or blisters will occur, ○ if slight red rust or blisters have occurred, △, many red rust and blisters will occur. When it did, it evaluated as x.
[0025]
[Table 2]
As is clear from Table 2, the content of boric acid contained in the conventional boric acid-containing Ni plating solution was adjusted by adjusting the content of a buffer such as citric acid instead of boric acid to 0.03 mol / l or more. It was found that a Ni plating film having excellent characteristics can be formed even if the amount is significantly reduced from the amount (plating solution 2 to plating solution 11).
[0027]
Example 3:
The sintered magnet obtained by the same method as in Example 1 was pickled and cleaned with diluted nitric acid. The Ni plating solution 4 of Example 1 was used for this magnet, and a Ni plating film having a thickness of 3 μm was formed on the magnet surface under the same electrical Ni plating conditions as in Example 1.
Next, nickel sulfate hexahydrate, nickel chloride hexahydrate and ammonium chloride were adjusted to the various concentrations shown in Table 3 and adjusted to the various concentrations shown in Table 3. Five types of Ni containing 0.02 g / l sodium lauryl sulfate and 0.5 g / l 2-butyne 1,4-diol as buffers and additives, and adjusting the pH to 5 by adding basic nickel carbonate Using the plating solution, under the same electric Ni plating conditions as in Example 1, a film having a thickness of 15 μm was formed on the surface of the first Ni plating film as the second Ni plating film. The performance of the formed Ni plating film is shown in Table 3.
[0028]
Evaluation of film soundness in Table 3 was carried out in the same manner as in Example 1. Corrosion resistance was evaluated in the same manner as in Example 2. The plating adhesion was evaluated by applying an epoxy resin (SW2214: thermosetting epoxy adhesive manufactured by Sumitomo 3M and then heating and curing at 120 ° C. for 60 minutes) to the plated magnet sample and bonding to the steel jig. after breaking strength at 180 ° shear compression test (plating peel strength) was measured, in the case of the adhesive strength is 400 kg / cm 2 or more ○, if the adhesion strength is 300kg / cm 2 ~400kg / cm 2 △ When the adhesive strength was less than 300 kg / cm 2 , the evaluation was made as x.
[0029]
[Table 3]
As is clear from Table 3, even if the Ni plating solution does not contain boric acid, the weight ratio of Ni ion concentration to the chlorine ion concentration (Ni 2+ / Cl − ) in the Ni plating solution is adjusted to a predetermined weight ratio. It was found that a Ni plating film with excellent characteristics can be formed by adjusting the content of a buffering agent such as citric acid instead of boric acid (plating solution 1 to plating solution 4).
[0031]
Example 4:
The sintered magnet obtained by the same method as in Example 1 was pickled and cleaned with diluted nitric acid. This magnet was subjected to per se known alkaline bath Cu plating to form a Cu plating film having a thickness of 3 μm on the magnet surface.
Next, nickel sulfate hexahydrate, nickel chloride hexahydrate and ammonium chloride were adjusted to the various concentrations shown in Table 4 and adjusted to the various concentrations shown in Table 4. Contains buffer, boric acid 8g / l, additive sodium lauryl sulfate 0.02g / l and 2-butyne 1,4-diol 0.5g / l, pH adjusted to 4 by adding basic nickel carbonate Using the adjusted five types of Ni plating solutions, a coating having a thickness of 10 μm was formed on the surface of the first layer Cu plating coating as the second layer Ni plating coating under the same electrical Ni plating conditions as in Example 1.
Finally, nickel sulfate hexahydrate 200 g / l, nickel chloride hexahydrate 40 g / l, ammonium chloride 10 g / l (weight ratio of Ni ion concentration to chloride ion concentration is 4.5), citric acid 2 Ni plating containing 45 g / l of ammonium (0.2 mol / l), 1 g / l of benzenesulfonic acid and 0.5 g / l of propargyl alcohol as additives, and adjusting the pH to 4 by adding basic nickel carbonate A second plating layer having a film thickness of 2 μm as a third layer Ni plating film under an electric Ni plating condition of a plating bath temperature of 50 ° C., a current density of 3 A / dm 2 , and a Ni plate as an anode. A layer Ni plating film was formed on the surface. Table 4 shows the performance of the formed Ni plating film. In addition, evaluation of the film soundness in Table 4 was performed in the same manner as in Example 1. Corrosion resistance was evaluated in the same manner as in Example 2.
[0032]
[Table 4]
As is apparent from Table 4, the weight ratio of Ni ion concentration to the chloride ion concentration (Ni 2+ / Cl − ) in the Ni plating solution is adjusted to a predetermined weight ratio, and contains a buffering agent such as citric acid instead of boric acid. It was found that a Ni plating film having excellent characteristics can be formed by adjusting the amount (plating solution 2 to plating solution 5).
[0034]
Example 5:
The sintered magnet obtained by the same method as in Example 1 was pickled and cleaned with diluted nitric acid. For this magnet, nickel sulfate hexahydrate, nickel chloride hexahydrate, and ammonium chloride adjusted to various concentrations shown in Table 5 with ammonium chloride, sodium citrate 2 water as a buffering agent Contains 147 g / l (0.5 mol / l) of Japanese product, 8 g / l of boric acid, 0.02 g / l of sodium lauryl sulfate and 0.5 g / l of 2-butyne 1,4-diol as additives Various nickel plating solutions adjusted to 5 by adding basic nickel carbonate were used, and under the same electric Ni plating conditions as in Example 1, various pulse electrolysis conditions (pulse periods T, T ON, and T OFF ), A nickel plating film having a film thickness of 3 μm was formed on the magnet surface while performing pulse electrolysis at a peak current density I p = 10 A / dm 2 .
Next, the Ni plating solution for forming the third layer Ni plating film of Example 4 was used, and the film thickness was 5 μm as the second layer Ni plating film under the same electric Ni plating conditions as in Example 4. A coating was formed on the surface of the first layer Ni plating coating. Table 5 shows the performance of the formed Ni plating film. In addition, evaluation of the film soundness in Table 5 was performed in the same manner as in Example 1. Corrosion resistance was evaluated in the same manner as in Example 2. Evaluation of plating adhesion was performed in the same manner as in Example 3.
[0035]
[Table 5]
As is apparent from Table 5, by performing electro Ni plating while performing pulse electrolysis, it is possible to perform electro Ni plating at a high current density (short time) and to form a Ni plating film having high corrosion resistance. It was found that the thickness of the Ni plating film can be reduced, and as a result, the dimensional accuracy can be improved (plating solution 1 to plating solution 4).
[0037]
【The invention's effect】
According to the electric Ni plating method of the present invention, by adjusting the weight ratio between the Ni ion concentration and the chloride ion concentration contained in the Ni plating solution, the use of a buffering agent instead of boric acid, and its content, Even if the content of boric acid is reduced, the Ni plating film formed using the Ni plating solution containing the conventional amount of boric acid has excellent characteristics such as uniform electrodeposition, denseness and appearance. A maintained Ni plating film can be formed. Further, it is possible to form a Ni plating film excellent in uniform electrodeposition by suppressing substitution deposition of Ni.
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001013288A JP4538959B2 (en) | 2001-01-22 | 2001-01-22 | Electric Ni plating method for rare earth permanent magnet |
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| JP2001013288A JP4538959B2 (en) | 2001-01-22 | 2001-01-22 | Electric Ni plating method for rare earth permanent magnet |
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| JP4538959B2 true JP4538959B2 (en) | 2010-09-08 |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP3883561B2 (en) * | 2003-03-05 | 2007-02-21 | Ｔｄｋ株式会社 | Rare earth magnet manufacturing method |
| DE112005000842B4 (en) * | 2004-04-15 | 2022-09-15 | Hitachi Metals, Ltd. | Method of imparting hydrogen resistance to an article |
| JP4666134B2 (en) * | 2004-09-13 | 2011-04-06 | 株式会社村田製作所 | Nickel plating bath and electronic parts |
| JP5263932B2 (en) * | 2008-02-28 | 2013-08-14 | 学校法人神奈川大学 | Plating solution and method for manufacturing cutting blade using the plating solution |
| JP4978665B2 (en) * | 2009-06-29 | 2012-07-18 | Ｔｄｋ株式会社 | Metal magnet and motor using the same |
| JP2013221188A (en) * | 2012-04-17 | 2013-10-28 | Yul Sup Sung | Phosphorus-free electroless nickel plating liquid, and electroless plating method using the same |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0613218A (en) * | 1992-06-24 | 1994-01-21 | Sumitomo Special Metals Co Ltd | Surface processing method of fe-b-r base sintered magnet |
| JPH09111491A (en) * | 1995-10-20 | 1997-04-28 | Nkk Corp | Nickel electroplating method |
| JPH11507991A (en) * | 1995-06-21 | 1999-07-13 | ペーター トーベン タン | Electroplating method for forming nickel, cobalt, nickel alloy or cobalt alloy plating |
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2001
- 2001-01-22 JP JP2001013288A patent/JP4538959B2/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0613218A (en) * | 1992-06-24 | 1994-01-21 | Sumitomo Special Metals Co Ltd | Surface processing method of fe-b-r base sintered magnet |
| JPH11507991A (en) * | 1995-06-21 | 1999-07-13 | ペーター トーベン タン | Electroplating method for forming nickel, cobalt, nickel alloy or cobalt alloy plating |
| JPH09111491A (en) * | 1995-10-20 | 1997-04-28 | Nkk Corp | Nickel electroplating method |
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| JP2002212775A (en) | 2002-07-31 |
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