JP4529260B2 - R-Fe-B permanent magnet and method for producing the same - Google Patents
R-Fe-B permanent magnet and method for producing the same Download PDFInfo
- Publication number
- JP4529260B2 JP4529260B2 JP2000276798A JP2000276798A JP4529260B2 JP 4529260 B2 JP4529260 B2 JP 4529260B2 JP 2000276798 A JP2000276798 A JP 2000276798A JP 2000276798 A JP2000276798 A JP 2000276798A JP 4529260 B2 JP4529260 B2 JP 4529260B2
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- film
- aluminum
- polyimide resin
- permanent magnet
- magnet
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Links
- 238000004519 manufacturing process Methods 0.000 title claims description 29
- 229910052782 aluminium Inorganic materials 0.000 claims description 118
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 117
- 229920001721 polyimide Polymers 0.000 claims description 94
- 239000009719 polyimide resin Substances 0.000 claims description 94
- 238000000034 method Methods 0.000 claims description 84
- 238000000576 coating method Methods 0.000 claims description 63
- 239000011248 coating agent Substances 0.000 claims description 62
- 239000010410 layer Substances 0.000 claims description 53
- 238000011282 treatment Methods 0.000 claims description 48
- 238000012545 processing Methods 0.000 claims description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 22
- 239000001301 oxygen Substances 0.000 claims description 22
- 229910052760 oxygen Inorganic materials 0.000 claims description 22
- 230000003647 oxidation Effects 0.000 claims description 17
- 238000007254 oxidation reaction Methods 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 15
- 238000007740 vapor deposition Methods 0.000 claims description 7
- 239000011247 coating layer Substances 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 2
- 239000010408 film Substances 0.000 description 218
- 230000007797 corrosion Effects 0.000 description 37
- 238000005260 corrosion Methods 0.000 description 37
- 238000012360 testing method Methods 0.000 description 24
- 238000010292 electrical insulation Methods 0.000 description 14
- 239000000843 powder Substances 0.000 description 10
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 9
- 230000001133 acceleration Effects 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 238000005755 formation reaction Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 238000005480 shot peening Methods 0.000 description 7
- 238000001035 drying Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 239000012071 phase Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 238000004544 sputter deposition Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000010419 fine particle Substances 0.000 description 5
- 238000007733 ion plating Methods 0.000 description 5
- 238000007747 plating Methods 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000000178 monomer Substances 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 239000007921 spray Substances 0.000 description 4
- 230000003746 surface roughness Effects 0.000 description 4
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 description 3
- HLBLWEWZXPIGSM-UHFFFAOYSA-N 4-Aminophenyl ether Chemical compound C1=CC(N)=CC=C1OC1=CC=C(N)C=C1 HLBLWEWZXPIGSM-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000001947 vapour-phase growth Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- -1 allyl nadic acid anhydride Chemical compound 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 150000003949 imides Chemical class 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 238000001771 vacuum deposition Methods 0.000 description 2
- XQUPVDVFXZDTLT-UHFFFAOYSA-N 1-[4-[[4-(2,5-dioxopyrrol-1-yl)phenyl]methyl]phenyl]pyrrole-2,5-dione Chemical compound O=C1C=CC(=O)N1C(C=C1)=CC=C1CC1=CC=C(N2C(C=CC2=O)=O)C=C1 XQUPVDVFXZDTLT-UHFFFAOYSA-N 0.000 description 1
- 125000003903 2-propenyl group Chemical group [H]C([*])([H])C([H])=C([H])[H] 0.000 description 1
- 229910052684 Cerium Inorganic materials 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
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 238000007259 addition reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 150000004984 aromatic diamines Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- NIDNOXCRFUCAKQ-UHFFFAOYSA-N bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid Chemical group C1C2C=CC1C(C(=O)O)C2C(O)=O NIDNOXCRFUCAKQ-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [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 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 230000005347 demagnetization Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- NINOVVRCHXVOKB-UHFFFAOYSA-N dialuminum;dioxido(dioxo)chromium Chemical compound [Al+3].[Al+3].[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O NINOVVRCHXVOKB-UHFFFAOYSA-N 0.000 description 1
- 150000004985 diamines Chemical class 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000003618 dip coating Methods 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 230000001747 exhibiting 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
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000001023 inorganic pigment Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000010303 mechanochemical reaction Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000012860 organic pigment Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 239000002798 polar solvent Substances 0.000 description 1
- 229920005575 poly(amic acid) Polymers 0.000 description 1
- 229920003192 poly(bis maleimide) Polymers 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 238000007348 radical reaction Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000007363 ring formation reaction Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 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
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
-
- 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)
- Chemical & Material Sciences (AREA)
- Power Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
- Powder Metallurgy (AREA)
- Physical Vapour Deposition (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
- Hard Magnetic Materials (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、Ｒ−Ｆｅ−Ｂ系永久磁石およびその製造方法に関する。より詳細には、自動車モータに使用される磁石などに求められる優れた耐食性・電気絶縁性・耐熱性を発揮するＲ−Ｆｅ−Ｂ系永久磁石およびその簡便な製造方法に関する。
【０００２】
【従来の技術】
Ｆｅ−Ｂ−Ｎｄ系永久磁石に代表されるＲ−Ｆｅ−Ｂ系永久磁石は、Ｓｍ−Ｃｏ系永久磁石に比べて、資源的に豊富で安価な材料が用いられ、かつ、高い磁気特性を有していることから、種々の用途で実用化されている。
しかしながら、Ｒ−Ｆｅ−Ｂ系永久磁石は、反応性の高いＲとＦｅを含むため、大気中で酸化腐食されやすく、何の表面処理をも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存在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、磁石特性の劣化やばらつきを招く。さらに、錆が発生した磁石を磁気回路などの装置に組み込んだ場合、錆が飛散して周辺部品を汚染するおそれがある。
【０００３】
上記の点に鑑み、Ｒ−Ｆｅ−Ｂ系永久磁石の耐食性を改善するため、磁石表面に無電解めっき法や電気めっき法のような湿式めっき法によって耐食性を有する金属めっき被膜を形成した磁石が既に提案されている（特公平３−７４０１２号公報参照）。しかしながら、この方法では、めっき処理の前処理で用いられる酸性溶液やアルカリ性溶液が磁石孔内に残留し、磁石が時間の経過とともに腐食することがある。また、該磁石は耐薬品性に劣るため、めっき処理時に磁石表面が腐食することがある。さらに、上記のように磁石表面に金属めっき被膜を形成しても、温度６０℃×相対湿度９０％の条件下での耐食性試験を行うと、１００時間後にその磁気特性が初期値よりも１０％以上劣化することがある。
【０００４】
また、Ｒ−Ｆｅ−Ｂ系永久磁石の表面にリン酸塩被膜やクロム酸塩被膜などの耐酸化性化成被膜を形成する方法も提案されているが（特公平４−２２００８号公報参照）、この方法で得られる被膜は磁石との密着性の点では優れるものの、温度６０℃×相対湿度９０％の条件下での耐食性試験を行うと、３００時間後にその磁気特性が初期値よりも１０％以上劣化することがある。
【０００５】
また、Ｒ−Ｆｅ−Ｂ系永久磁石の耐食性を改善するために提案された、気相成長法によってアルミニウム被膜を形成した後、クロム酸塩処理する方法、いわゆるアルミ−クロメート処理方法（特公平６−６６１７３号公報参照）は、磁石の耐食性を著しく改善するものである。しかしながら、この方法に用いるクロム酸塩処理は、環境上望ましくない六価クロムを用いるため、廃液処理方法が複雑である。また、この方法によって得られる被膜は、微量ながら六価クロムを含有するため、磁石の取り扱い時における人体に対する影響も懸念される。
【０００６】
【発明が解決しようとする課題】
一方、自動車モータに組み込まれて使用されるＲ−Ｆｅ−Ｂ系永久磁石には、耐食性についてはもちろんのこと、電気絶縁性や耐熱性についても優れた性能が求められるが、上記のアルミ−クロメート処理方法では、優れた電気絶縁性と耐熱性を付与することはできない。
そこで、本発明においては、自動車モータに使用される磁石などに求められる優れた耐食性・電気絶縁性・耐熱性を発揮するＲ−Ｆｅ−Ｂ系永久磁石および溶液法を用いたその簡便な製造方法を提供することを目的としている。
【０００７】
【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鋭意検討を行った結果、Ｒ−Ｆｅ−Ｂ系永久磁石表面にアルミニウム被膜を形成し、その上にポリイミド樹脂被膜を形成することで、優れた耐食性に加え、優れた電気絶縁性と耐熱性を発揮させることに想到した。
Ｒ−Ｆｅ−Ｂ系永久磁石表面にアルミニウム被膜を形成し、その上にポリイミド樹脂被膜を形成する技術は、すでに、特開平８−２７９４０７号公報に開示されている。しかしながら、該技術におけるポリイミド樹脂被膜の形成方法は、二種類の原料モノマー（芳香族カルボン酸二無水物と芳香族ジアミン）を用いて縮合型ポリイミド樹脂被膜を蒸着重合法によって形成するものである。この技術はアルミニウム被膜の上に優れた性能を有するポリイミド樹脂被膜を形成する方法として価値あるものであるが、蒸着重合法を行うためには大がかりな装置が必要である。また、清浄化などの前処理を厳格に行わなければならない。したがって、製造コストの上昇を招き、量産化の観点からは必ずしも満足すべきものではない。
【０００８】
本発明者らは上記の点に鑑みさらに鋭意検討を行った結果、Ｒ−Ｆｅ−Ｂ系永久磁石上のアルミニウム被膜表面に酸化被膜層を形成し、その上にポリイミド樹脂被膜を形成すると、酸化被膜層の存在によって、ポリイミド樹脂被膜はアルミニウム被膜表面に強固に密着し、アルミニウム被膜とともに優れた耐食性・電気絶縁性・耐熱性を発揮することを知見した。また、酸化被膜層の上では、ポリイミド樹脂被膜形成反応が効率よく進行し、溶液法によってもアルミニウム被膜表面に対して優れた密着性を有する被膜が得られることを知見した。
【０００９】
本発明は、かかる知見に基づきなされたもので、本発明の永久磁石は、請求項１記載の通り、Ｒ−Ｆｅ−Ｂ系永久磁石表面に、アルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜として付加型ポリイミド樹脂被膜を有することを特徴とする。
また、請求項２記載の永久磁石は、請求項１記載の永久磁石において、付加型ポリイミド樹脂被膜がビスアリルナジイミドから得られる被膜であることを特徴とする。
また、請求項３記載の永久磁石は、請求項１または２記載の永久磁石において、アルミニウム被膜の膜厚が０．０１μｍ〜５０μｍであることを特徴とする。
また、請求項４記載の永久磁石は、請求項１乃至３のいずれかに記載の永久磁石において、酸化被膜層の膜厚が０．０１μｍ〜２μｍであることを特徴とする。
また、請求項５記載の永久磁石は、請求項１乃至４のいずれかに記載の永久磁石において、ポリイミド樹脂被膜の膜厚が１μｍ〜１５μｍであることを特徴とする。
また、本発明の永久磁石の製造方法は、請求項６記載の通り、Ｒ−Ｆｅ−Ｂ系永久磁石表面に、アルミニウム被膜を形成した後、前記アルミニウム被膜表面に、酸素雰囲気中での酸化処理によって酸化被膜層を形成し、前記酸化被膜層表面に、ポリイミド樹脂被膜形成処理液を塗布し、熱処理することによってポリイミド樹脂被膜を形成することを特徴とする。
また、請求項７記載の製造方法は、請求項６記載の製造方法において、気相成長法によってアルミニウム被膜を形成することを特徴とする。
また、請求項８記載の製造方法は、請求項７記載の製造方法において、膜厚が０．０１μｍ〜５０μｍのアルミニウム被膜を形成することを特徴とする。
また、請求項９記載の製造方法は、請求項６記載の製造方法において、Ｒ−Ｆｅ−Ｂ系永久磁石とアルミニウム片を処理容器内に入れ、前記処理容器内にて、両者に振動を加え、および／または両者を攪拌することによってアルミニウム被膜を形成することを特徴とする。
また、請求項１０記載の製造方法は、請求項９記載の製造方法において、膜厚が０．０１μｍ〜１μｍのアルミニウム被膜を形成することを特徴とする。
また、請求項１１記載の製造方法は、請求項６乃至１０のいずれかに記載の製造方法において、酸素雰囲気中での酸化処理を、酸素濃度が０．０１％〜２０％の常圧下、または酸素圧（分圧）が０．１Ｐａ〜２×１０４Ｐａの減圧下、１０℃〜５００℃にて行うことを特徴とする。
また、請求項１２記載の製造方法は、請求項６乃至１１のいずれかに記載の製造方法において、ポリイミド樹脂被膜が付加型ポリイミド樹脂被膜であることを特徴とする。
また、請求項１３記載の製造方法は、請求項１２記載の製造方法において、付加型ポリイミド樹脂被膜がビスアリルナジイミドから得られる被膜であることを特徴とする。
【００１０】
【発明の実施の形態】
本発明の永久磁石は、Ｒ−Ｆｅ−Ｂ系永久磁石表面に、アルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有することを特徴とする。
【００１１】
Ｒ−Ｆｅ−Ｂ系永久磁石表面にアルミニウム被膜を形成する方法は特段限定されるものではない。しかしながら、磁石とアルミニウム被膜が酸化腐食されやすいことに配慮すれば、以下の、気相成長法による方法とＲ−Ｆｅ−Ｂ系永久磁石とアルミニウム片を処理容器内に入れ、前記処理容器内にて、両者に振動を加え、および／または両者を攪拌することによる方法が望ましい方法として挙げられる。
【００１２】
（１）気相成長法による方法
アルミニウム被膜を形成するために採用することができる気相成長法としては、真空蒸着法、イオンスパッタリング法、イオンプレーティング法などの公知の方法が挙げられる。アルミニウム被膜は各方法における一般的な条件にて形成すればよいが、形成される被膜の緻密性、膜厚の均一性、被膜形成速度などの観点からは真空蒸着法やイオンプレーティング法を採用することが望ましい。なお、被膜形成前に磁石表面に対し、洗浄、脱脂、スパッタリングなどの公知の清浄化処理を施してもよいことは言うまでもない。
【００１３】
被膜形成時における磁石の温度は、２００℃〜５００℃に設定することが望ましい。該温度が２００℃未満であると磁石表面に対して優れた密着性を有する被膜が形成されないおそれがあり、５００℃を越えると被膜形成後の冷却過程で被膜に亀裂が発生し、被膜が磁石から剥離するおそれがあるからである。
【００１４】
アルミニウム被膜の膜厚は、０．０１μｍ未満であると優れた耐食性を発揮できないおそれがあり、５０μｍを越えると製造コストの上昇を招くおそれがあるだけでなく、磁石の有効体積が小さくなるおそれがあるので、０．０１μｍ〜５０μｍが望ましいが、０．０５μｍ〜２５μｍがより望ましい。
【００１５】
（２）Ｒ−Ｆｅ−Ｂ系永久磁石とアルミニウム片を処理容器内に入れ、前記処理容器内にて、両者に振動を加え、および／または両者を攪拌することによる方法本方法において用いるアルミニウム片は、針状（ワイヤー状）、円柱状、塊状など様々な形状のものを用いることができるが、アルミニウム被膜の構成源となるアルミニウム微粉を効率よく生成させるためなどの観点からは、末端が鋭利な針状や円柱状のものを用いることが望ましい。
【００１６】
アルミニウム片の大きさ（長径）は、アルミニウム微粉を効率よく生成させるためなどの観点から、０．０５ｍｍ〜１０ｍｍが望ましいが、より望ましくは０．３ｍｍ〜５ｍｍであり、さらに望ましくは０．５ｍｍ〜３ｍｍである。アルミニウム片は同一形状・同一寸法のものを用いてもよく、異形状・異寸法のものを混合して用いてもよい。
【００１７】
磁石とアルミニウム片に対する、振動および／または攪拌は、両者が酸化腐食されやすいことに配慮して、乾式的に行うことが望ましく、大気雰囲気中、常温において行うことができる。本発明において用いうる処理容器は、複雑な装置のものを必要とせず、たとえば、バレル装置の処理室などでよい。バレル装置は回転式、振動式、遠心式など、公知の装置を用いることができる。回転式の場合、その回転数は２０ｒｐｍ〜５０ｒｐｍとすることが望ましい。振動式の場合、その振動数は５０Ｈｚ〜１００Ｈｚ、振動振幅は０．３ｍｍ〜１０ｍｍとすることが望ましい。遠心式の場合、その回転数は７０ｒｐｍ〜２００ｒｐｍとすることが望ましい。
【００１８】
処理容器内に入れる磁石とアルミニウム片の量は、処理容器内容積の２０ｖｏｌ％〜９０ｖｏｌ％が望ましい。２０ｖｏｌ％未満であると処理量が少なすぎて実用的でなく、９０ｖｏｌ％を越えると効率よく被膜を形成することができないおそれがあるからである。また、処理容器内に入れる磁石とアルミニウム片との比率は、容積比率（磁石／アルミニウム片）にして３以下が望ましい。容積比率が３を越えると被膜の形成に時間を要して実用的でないおそれがあるからである。また、処理時間は処理量にも依存するが、通常、１時間〜１０時間である。
【００１９】
上記の方法によって、アルミニウム片から生成されるアルミニウム微粉を磁石表面に被着させ、アルミニウム被膜を形成する。アルミニウム微粉が磁石表面に被着する現象は、一種のメカノケミカル的反応であると考えられ、アルミニウム微粉は磁石表面に強固に被着し、得られるアルミニウム被膜は優れた耐食性を示す。十分な耐食性を確保する観点からは、前述の通り、その膜厚は０．０１μｍ以上であることが望ましい。膜厚の上限は特段制限されるものではないが、膜厚が１μｍを越えるアルミニウム被膜を形成するには時間を要するので、この方法は膜厚が１μｍ以下のアルミニウム被膜を形成する方法として適している。
【００２０】
アルミニウム被膜表面に酸化被膜層を形成する前工程として、ショットピーニング（硬質粒子を衝突させることによって表面を改質する方法）を行ってもよい。ショットピーニングを行うことによって、アルミニウム被膜の平滑化を行い、アルミニウム被膜自体の耐食性を向上させるとともに、均一な酸化被膜層を形成しやすくして、薄膜でも優れた性能を有するポリイミド樹脂被膜を形成しやすくすることができる。
ショットピーニングに用いる粉末としては、形成したアルミニウム被膜の硬度と同等以上の硬度のものが望ましく、たとえば、スチールボールやガラスビーズなどのようなモース硬度が３以上の球状硬質粉末が挙げられる。該粉末の平均粒度が３０μｍ未満であるとアルミニウム被膜に対する押圧力が小さくて処理に時間を要する。一方、３０００μｍを越えると表面粗度が荒くなりすぎて仕上がり面が不均一となるおそれがある。したがって、該粉末の平均粒径は、３０μｍ〜３０００μｍが望ましく、４０μｍ〜２０００μｍがより望ましい。
ショットピーニングにおける噴射圧は、１．０ｋｇ／ｃｍ２〜５．０ｋｇ／ｃｍ２が望ましい。噴射圧が１．０ｋｇ／ｃｍ２未満であると金属被膜に対する押圧力が小さくて処理に時間を要し、５．０ｋｇ／ｃｍ２を越えると金属被膜に対する押圧力が不均一になって表面粗度の悪化を招くおそれがあるからである。
ショットピーニングにおける噴射時間は、１分〜１時間が望ましい。噴射時間が１分未満であると全表面に対して均一な処理ができないおそれがあり、１時間を越えると表面粗度の悪化を招くおそれがあるからである。
【００２１】
磁石表面にアルミニウム被膜を形成した後、熱処理することによって、磁石表面とアルミニウム被膜との密着性を高めることもできる。熱処理の温度は、２００℃未満であると磁石とアルミニウム被膜との界面反応が十分に進行せずに密着性が向上しないおそれがあり、５００℃を越えると磁石の磁気特性の劣化を招くおそれや、アルミニウム被膜が溶解してしまうおそれがある。したがって、熱処理は、２００℃〜５００℃で行うことが望ましいが、生産性や製造コストの観点からは２００℃〜３５０℃で行うことがより望ましい。なお、後述する酸化被膜層表面にポリイミド樹脂被膜形成処理液を塗布した後の熱処理によっても同様の効果を得ることができる。
【００２２】
アルミニウム被膜表面に酸化被膜層を形成する方法としては、たとえば、酸素雰囲気中での酸化処理方法、水蒸気を含む雰囲気中での酸化処理方法（一般的な水蒸気処理を含む）などが挙げられる。
酸素雰囲気中での酸化処理方法には、たとえば、処理室内で酸素濃度と温度を制御しながら行う方法や大気中での自然酸化などがある。処理条件としては、酸素濃度が０．０１％〜２０％の常圧下、または酸素圧（分圧）が０．１Ｐａ〜２×１０４Ｐａの減圧下、１０℃〜５００℃にて行うことが望ましい。酸素濃度が０．０１％〜２０％の常圧条件は、大気自体を利用したものであってもよいし、窒素ガスやアルゴンガスなどの不活性ガスを用いて所望する成分組成に調整されたものであってもよい。酸素圧（分圧）が０．１Ｐａ〜２×１０４Ｐａの減圧条件は、酸素圧のみで調整されたものであってもよいし、窒素ガスやアルゴンガスなどの不活性ガスを用いて所望する成分組成や圧力に調整されたものであってもよい。酸化処理を１０℃〜５００℃で行うことが望ましい理由は、５００℃を超えると、磁石の磁気特性の劣化やアルミニウム被膜の変形を招くおそれがあるからである。また、処理温度が高くなるにつれて、緻密で薄い酸化被膜層を形成することが困難となったり、酸化被膜層の表面粗度が粗くなることによって、ポリイミド樹脂被膜の形成に悪影響を及ぼし、結果的に優れた耐食性などの性能を有する磁石が得られないおそれがあるからである。上記の処理条件にて処理室内で酸化処理を行う場合の処理時間は、通常、５分〜４８時間である。酸素雰囲気中での酸化処理方法としては、上記のような方法の他にも、前述のアルミニウム被膜表面に対するショットピーニングや、ショットブラスト処理、弱電圧下でのスパッタ処理や高周波による酸素プラズマ形成下での酸化処理などがある。
水蒸気を含む雰囲気中での酸化処理方法（一般的な水蒸気処理を含む）は、水蒸気濃度と温度を制御しながら行うものであり、その具体的な処理条件は、たとえば、水蒸気濃度が０．０１％〜１００％、処理温度が１０℃〜３００℃である。
【００２３】
上記のような方法によって形成される酸化被膜層の膜厚は、０．０１μｍ以上であることが望ましい。膜厚が０．０１μｍ未満であるとアルミニウム被膜表面へのポリイミド樹脂被膜の優れた密着性に寄与しないおそれがあるからである。一方、酸化被膜層の膜厚は、２μｍ以下であることが望ましい。膜厚が２μｍを超えるとアルミニウム被膜表面へのポリイミド樹脂被膜の優れた密着性を逆に阻害するおそれがあるからである。さらに、磁石自体の小型化に基づく要請などを加味すれば、酸化被膜層の膜厚は、１μｍ以下であることがより望ましい。
【００２４】
次に、酸化被膜層表面にポリイミド樹脂被膜を形成する方法について述べる。
ポリイミド樹脂被膜は、付加型ポリイミド樹脂被膜であっても縮合型ポリイミド樹脂被膜であってもよいが、望ましくは、付加型ポリイミド樹脂被膜がよい。付加型ポリイミド樹脂は、樹脂分子の末端に不飽和基を有し、付加反応やラジカル反応による三次元架橋により得られるものであるが、硬化に際して水が生成することがないので、磁石が酸化腐食されやすいことを考慮すれば非常に都合のよい樹脂である。付加型ポリイミド樹脂としては、無水アリルナジック酸とジアミンから合成され、脱水閉環反応が完結した両末端にアリル基を有するイミドモノマーであるビスアリルナジイミド（ＢＡＮＩ：図１参照）から得られる樹脂の他、末端ナジック酸型ポリイミド樹脂（ＰＭＲ）、ビスマレイミド型ポリイミド樹脂、末端アセチレン型ポリイミド樹脂など公知のものを使用することができる。
【００２５】
【化１】
縮合型ポリイミド樹脂としては、ピロメリット酸二無水物と４，４’−ジアミノジフェニルエーテルから脱水縮合反応を経て得られるピロメリット型ポリイミド樹脂が挙げられる。縮合型ポリイミド樹脂は、硬化に際して水が生成するが、酸化被膜層は、磁石表面のいわば保護層として水が磁石表面に接触しにくくする役割を果たすので、優れた密着性を有するポリイミド樹脂被膜をアルミニウム被膜表面に形成することができる。
【００２７】
酸化被膜層表面へのポリイミド樹脂被膜の形成は、ポリイミド樹脂被膜形成処理液を酸化被膜層表面に塗布し、熱処理する方法（いわゆる溶液法）によって行うことが、蒸着重合法と比較して簡便に行え、製造コストの上昇を招くことなく量産化が可能となる点において望ましい。
【００２８】
ポリイミド樹脂被膜形成処理液は、ポリイミド樹脂自体、ポリイミド樹脂の原料となるモノマーやオリゴマーなどを必要に応じて有機溶媒に溶解して調製すればよい。たとえば、ビスアリルナジイミドは、かさ高い構造を有した低分子量のイミドモノマーであるので、脂肪族炭化水素、脂肪族アルコールを除くほとんどの有機溶媒に可溶である。また、ピロメリット型ポリイミド樹脂被膜を形成するための溶液は、たとえば、ピロメリット酸二無水物と４，４’−ジアミノジフェニルエーテルを高極性溶媒のＮ−メチル−２−ピロリドンに溶解して調製すればよい。
【００２９】
ポリイミド樹脂被膜形成処理液の酸化被膜層表面への塗布方法としては、ディップコーティング法、スプレー法、スピンコート法などを用いることができる。
【００３０】
酸化被膜層表面にポリイミド樹脂被膜形成処理液を塗布した後の熱処理は、２００℃〜４００℃で行うことが望ましい。２００℃未満であると硬化反応が十分に進行しないおそれがあり、４００℃を越えると被膜の劣化を招くおそれがあるからである。熱処理時間は、通常、５分〜２４時間である。
なお、必要に応じて、熱処理を行う前に、有機溶媒を除去するための乾燥処理（たとえば、６０℃〜９０℃の条件下、５分〜１時間）を行ってもよい。
【００３１】
酸化被膜層表面へのポリイミド樹脂被膜の形成は、上記のポリイミド樹脂被膜形成処理液を酸化被膜層表面に塗布し、熱処理する方法に限られるものではなく、蒸着重合法によって行ってもよい。たとえば、酸化被膜層表面にピロメリット型ポリイミド樹脂被膜を蒸着重合法によって形成する場合は、表面に酸化被膜層を有するアルミニウム被膜付磁石を真空度１Ｐａ〜１０−３Ｐａの真空容器内に収容し、ピロメリット酸二無水物と４，４’−ジアミノジフェニルエーテルを２００℃〜２５０℃で加熱蒸着してポリアミック酸被膜を形成した後、常圧下、２８０℃〜３８０℃でイミド化処理を行う方法が挙げられる（特開平８−２７９４０７号公報を参照）。
【００３２】
上記の方法によって形成されるポリイミド樹脂被膜は、酸化被膜層を介して、アルミニウム被膜表面に強固に密着しているので、膜厚が１μｍ以上であれば優れた耐食性などの性能を発揮する。なお、ポリイミド樹脂被膜の膜厚の上限は限定されるものではないが、磁石自体の小型化に基づく要請から、１５μｍ以下が望ましく、１０μｍ以下がより望ましい。なお、必要に応じて、酸化被膜層表面へのポリイミド樹脂被膜形成処理液の塗布、それに続く熱処理を複数回繰り返して行ってもよいことはいうまでもない。
さらに、ポリイミド樹脂被膜の各種性能（耐磨耗性や滑り性など）を高めるために、被膜中にチタンやニッケルなどの金属の微粒子、アルミナやシリカなどのセラミックスや金属酸化物などの微粒子、テフロンなどの合成樹脂の微粒子、その他、有機顔料や無機顔料として使用される各種微粒子を分散させてもよい。たとえば、被膜中に粒径１μｍのテフロン球を２０重量％程度分散させれば、ポリイミド樹脂被膜の滑り性を向上させることができる。添加する微粒子の大きさや形状は、形成される被膜の性能や膜厚などを考慮して適宜選択されるものであるが、通常、粒径０．０１μｍ〜５μｍの微粒子を使用することができる。
【００３３】
本発明において用いられる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用いることもできる。
Ｒ−Ｆｅ−Ｂ系永久磁石におけるＲの含量は、１０原子％未満であると結晶構造がα−Ｆｅと同一構造の立方晶組織となるため、高磁気特性、特に高い保磁力（ＨｃＪ）が得られず、一方、３０原子％を超えるとＲリッチな非磁性相が多くなり、残留磁束密度（Ｂｒ）が低下して優れた特性の永久磁石が得られないので、組成の１０原子％〜３０原子％であることが望ましい。
【００３４】
Ｆｅの含量は、６５原子％未満であるとＢｒが低下し、８０原子％を超えると高いＨｃＪが得られないので、６５原子％〜８０原子％の含有が望ましい。
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が、Ｃｏ置換量がＦｅの２０原子％を超えると磁気特性が劣化するので望ましくない。Ｃｏ置換量が５原子％〜１５原子％の場合、Ｂｒは置換しない場合に比較して増加するため、高磁束密度を得るのに望ましい。
【００３５】
Ｂの含量は、２原子％未満であると菱面体構造が主相となり、高いＨｃＪは得られず、２８原子％を超えるとＢリッチな非磁性相が多くなり、Ｂｒが低下して優れた特性の永久磁石が得られないので、２原子％〜２８原子％の含有が望ましい。
また、磁石の製造性の改善や低価格化のために、２．０ｗｔ％以下のＰ、２．０ｗｔ％以下のＳのうち、少なくとも１種、合計量で２．０ｗｔ％以下を含有していてもよい。さらに、Ｂの一部を３０ｗｔ％以下のＣで置換することによって、磁石の耐食性を改善することができる。
【００３６】
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種の添加は、保磁力や減磁曲線の角型性の改善、製造性の改善、低価格化に効果がある。なお、その添加量は、最大エネルギー積（ＢＨ）ｍａｘを１５９ｋＪ／ｍ３以上とするためには、Ｂｒが少なくとも０．９Ｔ以上必要となるので、該条件を満たす範囲で添加することが望ましい。
なお、Ｒ−Ｆｅ−Ｂ系永久磁石には、Ｒ、Ｆｅ、Ｂ以外に工業的生産上不可避な不純物を含有するものでも差し支えない。
【００３７】
また、本発明において用いられるＲ−Ｆｅ−Ｂ系永久磁石の中で、平均結晶粒径が１μｍ〜８０μｍの範囲にある正方晶系の結晶構造を有する化合物を主相とし、体積比で１％〜５０％の非磁性相（酸化物相を除く）を含むことを特徴とする磁石は、ＨｃＪ≧８０ｋＡ／ｍ、Ｂｒ＞０．４Ｔ、（ＢＨ）ｍａｘ≧８０ｋＪ／ｍ３を示し、（ＢＨ）ｍａｘの最大値は１９９ｋＪ／ｍ３以上に達する。
【００３８】
なお、本発明のポリイミド樹脂被膜の上に、更に別の被膜を積層形成してもよい。このような構成を採用することによって、ポリイミド樹脂被膜の特性を増強・補完したり、さらなる機能性を付与したりすることができる。
【００３９】
【実施例】
たとえば、米国特許４７７０７２３号公報に記載されているようにして、公知の鋳造インゴットを粉砕し、微粉砕後に成形、焼結、熱処理、表面加工を行うことによって得られた１７Ｎｄ−１Ｐｒ−７５Ｆｅ−７Ｂ組成の２３ｍｍ×１０ｍｍ×６ｍｍ寸法の焼結磁石（以下「磁石体試験片」と称する）を用いて以下の実験を行った。以下の実験において、アルミニウム被膜の膜厚、酸化被膜層の膜厚およびポリイミド樹脂被膜の膜厚は破断面の電子顕微鏡観察によって測定した。
なお、本発明は、Ｒ−Ｆｅ−Ｂ系焼結磁石への適用に限られるものではなく、Ｒ−Ｆｅ−Ｂ系ボンド磁石に対しても適用できるものである。
【００４０】
実験例１：
真空容器内に磁石体試験片を収容し、内部を１×１０−４Ｐａ以下に真空排気した後、Ａｒガス圧１０Ｐａ、バイアス電圧−４００Ｖの条件下で、１５分スパッタリングを行い、磁石表面を清浄化した。
次に、Ａｒガス圧１０Ｐａ、バイアス電圧−５０Ｖ、磁石温度２５０℃の条件下で、ターゲットとして金属アルミニウムを用い、２０分アークイオンプレーティングを行い、磁石表面にアルミニウム被膜を形成し、放冷した。得られたアルミニウム被膜の膜厚は１．１μｍであった。
上記の方法で得られた、アルミニウム被膜付磁石を直ちに処理室内に収容し、酸素濃度５％の常圧下（詳細は表１参照）、温度２００℃で、１０分酸化処理を行い、アルミニウム被膜表面に酸化被膜層を形成した。形成された酸化被膜層の膜厚は０．３μｍであった。
ポリイミド樹脂被膜形成処理液として、ＢＡＮＩ−Ｍ（商品名・丸善石油化学社製）を、有機溶媒としてトルエンを用いて２０％（ｖｏｌ／ｖｏｌ）に希釈した溶液を調製した。これを、上記の方法で得られた、表面に酸化被膜層を有するアルミニウム被膜付磁石にスプレー法によって塗布した。続いて、８０℃にて１０分乾燥した後、２５０℃にて１５分熱処理を行い、酸化被膜層表面にポリイミド樹脂被膜を形成した。形成されたポリイミド樹脂被膜の膜厚は５μｍであった。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有する磁石を、温度７０℃×相対湿度９０％の高温高湿条件下に放置して耐食性加速試験を行った。その結果、試験開始から５００時間経過しても発錆や被膜剥離などは観察されず、優れた耐食性を示した。
また、電気絶縁性を体積抵抗率（ρ）によって評価したところ、１×１０１５Ω・ｃｍ以上という優れた値を示した。なお、体積抵抗率は、サンプルに電極付けを行い、被膜表面と磁石間の抵抗を測定し、ρ＝Ｒ・Ｓ／ｌの数式から求めた（Ｒ：抵抗（Ω）、Ｓ：電極面積（ｃｍ２）、ｌ：ポリイミド樹脂被膜膜厚（ｃｍ））。耐熱性を熱変形温度によって評価したところ、２８０℃以上という優れた値を示した。なお、熱変形温度は、大気中２０時間その温度に放置して被膜の変色、亀裂などが生じる温度とした。
【００４１】
実験例２：
実験例１において、スプレー法による塗布と乾燥をもう一度繰り返して行った後に熱処理を行った以外は実験例１と同一条件で、膜厚が１０μｍのポリイミド樹脂被膜を形成した。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有する磁石に対し、実験例１と同一条件の耐食性加速試験を行った。その結果、試験開始から５００時間経過しても発錆や被膜剥離などは観察されず、優れた耐食性を示した。また、電気絶縁性を体積抵抗率（ρ）によって評価したところ、１×１０１５Ω・ｃｍ以上という優れた値を示した。耐熱性を熱変形温度によって評価したところ、２８０℃以上という優れた値を示した。
【００４２】
実験例３：
磁石体試験片に対し、実験例１と同一条件でスパッタリングを行い、磁石表面を清浄化した。次に、Ａｒガス圧１Ｐａ、電圧１．５ＫＶの条件下で、コーティング材料としてアルミニウムワイヤーを用い、これを加熱蒸発させてイオン化し、２．５分イオンプレーティングを行い、磁石表面にアルミニウム被膜を形成し、放冷した。得られたアルミニウム被膜の膜厚は２μｍであった。
その後、Ｎ２ガスからなる加圧気体とともに、平均粒径１２０μｍ、モース硬度６の球状ガラスビーズ粉末を、噴射圧１．５ｋｇ／ｃｍ２にて１０分、アルミニウム被膜表面に対して噴射して、ショットピーニングを施した。
上記の方法で得られた、アルミニウム被膜付磁石を直ちに処理室内に収容し、酸素濃度０．１％の常圧下（詳細は表１参照）、温度２５０℃で、７分酸化処理を行い、アルミニウム被膜表面に酸化被膜層を形成した。形成された酸化被膜層の膜厚は０．２μｍであった。
上記の方法で得られた、表面に酸化被膜層を有するアルミニウム被膜付磁石に対し、実験例１で使用したものと同じポリイミド樹脂被膜形成処理液を使用し、実験例１と同じ条件にて、膜厚が５μｍのポリイミド樹脂被膜を形成した。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有する磁石に対し、実験例１と同一条件の耐食性加速試験を行った。その結果、試験開始から５００時間経過しても発錆や被膜剥離などは観察されず、優れた耐食性を示した。また、電気絶縁性を体積抵抗率（ρ）によって評価したところ、１×１０１５Ω・ｃｍ以上という優れた値を示した。耐熱性を熱変形温度によって評価したところ、２８０℃以上という優れた値を示した。
【００４３】
実験例４:
実験例３において、スプレー法による塗布と乾燥をもう一度繰り返して行った後に熱処理を行った以外は実験例３と同一条件で、膜厚が１０μｍのポリイミド樹脂被膜を形成した。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有する磁石に対し、実験例１と同一条件の耐食性加速試験を行った。その結果、試験開始から５００時間経過しても発錆や被膜剥離などは観察されず、優れた耐食性を示した。また、電気絶縁性を体積抵抗率（ρ）によって評価したところ、１×１０１５Ω・ｃｍ以上という優れた値を示した。耐熱性を熱変形温度によって評価したところ、２８０℃以上という優れた値を示した。
【００４４】
実験例５:
１００個の磁石体試験片（見かけ容量０．３５リットル、重量１．１ｋｇ）と直径０．８ｍｍ、長さ１ｍｍの短円柱状アルミニウム片（見かけ容量２０リットル、重量１００ｋｇ）を容積５０リットルの振動バレル装置の処理室に投入し（合計投入量は処理室内容積の３０ｖｏｌ％）、振動数６０Ｈｚ、振動振幅１．８ｍｍの条件にて乾式的に処理を７時間行い、磁石表面にアルミニウム被膜を形成した。得られたアルミニウム被膜の膜厚は０．２μｍであった。
上記の方法で得られた、アルミニウム被膜付磁石を直ちに処理室内に収容し、酸素濃度０．２％の常圧下（詳細は表１参照）、温度１８０℃で、６分酸化処理を行い、アルミニウム被膜表面に酸化被膜層を形成した。形成された酸化被膜層の膜厚は０．１μｍであった。
上記の方法で得られた、表面に酸化被膜層を有するアルミニウム被膜付磁石に対し、実験例１で使用したものと同じポリイミド樹脂被膜形成処理液を使用し、実験例１と同じ条件にて、膜厚が５μｍのポリイミド樹脂被膜を形成した。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有する磁石に対し、実験例１と同一条件の耐食性加速試験を行った。その結果、試験開始から５００時間経過しても発錆や被膜剥離などは観察されず、優れた耐食性を示した。また、電気絶縁性を体積抵抗率（ρ）によって評価したところ、１×１０１５Ω・ｃｍ以上という優れた値を示した。耐熱性を熱変形温度によって評価したところ、２８０℃以上という優れた値を示した。
【００４５】
実験例６:
実験例１と同様の方法で得た、膜厚が１．１μｍのアルミニウム被膜付磁石を直ちに処理室内に収容し、酸素圧１０Ｐａの減圧下（詳細は表１参照）、温度２２０℃で、１５分酸化処理を行い、アルミニウム被膜表面に酸化被膜層を形成した。形成された酸化被膜層の膜厚は０．６μｍであった。
上記の方法で得られた、表面に酸化被膜層を有するアルミニウム被膜付磁石に対し、実験例１で使用したものと同じポリイミド樹脂被膜形成処理液を使用し、実験例１と同じ条件にて、膜厚が５μｍのポリイミド樹脂被膜を形成した。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有する磁石に対し、実験例１と同一条件の耐食性加速試験を行った。その結果、試験開始から５００時間経過しても発錆や被膜剥離などは観察されず、優れた耐食性を示した。また、電気絶縁性を体積抵抗率（ρ）によって評価したところ、１×１０１５Ω・ｃｍ以上という優れた値を示した。耐熱性を熱変形温度によって評価したところ、２８０℃以上という優れた値を示した。
【００４６】
【表１】
比較例１：
磁石体試験片に対し、実験例１と同一条件でスパッタリングを行い、磁石表面を清浄化した。次に、実験例１と同一条件でアークイオンプレーティングを行い、磁石表面にアルミニウム被膜を形成し、放冷した。得られたアルミニウム被膜の膜厚は１．５μｍであった。次に、アルミニウム被膜表面に酸化被膜層を形成することなく、実験例１で使用したものと同じポリイミド樹脂被膜形成処理液を使用し、実験例１と同じ条件にて、膜厚が５μｍのポリイミド樹脂被膜を直接に形成した。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に直接に、ポリイミド樹脂被膜を有する磁石に対し、実験例１と同一条件の耐食性加速試験を行った。その結果、試験開始から１５０時間で被膜剥離が観察された。
【００４８】
比較例２：
比較例１において、スプレー法による塗布と乾燥をもう一度繰り返して行った後に熱処理を行った以外は比較例と同一条件で、膜厚が１０μｍのポリイミド樹脂被膜を形成した。
上記の方法で得られた、表面にアルミニウム被膜を有し、前記アルミニウム被膜表面に直接に、ポリイミド樹脂被膜を有する磁石に対し、実験例１と同一条件の耐食性加速試験を行った。その結果、試験開始から２５０時間で被膜剥離が観察された。
【００４９】
実験例７〜実験例１２：
実験例１〜実験例６と同様の条件にて磁石体試験片の表面にアルミニウム被膜を形成し、その表面に酸化被膜層を形成した後、各実験例におけるポリイミド樹脂被膜形成処理液の調製に用いたトルエンの代わりにトルエンと酢酸エチルとシクロヘキサノンの混合溶媒（容積比６５：１５：２０）を用いる以外は各実験例と同様の条件、膜厚にて酸化被膜層表面にポリイミド樹脂被膜を形成した。各サンプルに対して実験例１と同様の耐食性加速試験、電気絶縁性評価、耐熱性評価を行ったところ、いずれのサンプルも各実験例のサンプルと同様の結果を示した。
【００５０】
【発明の効果】
本発明のＲ−Ｆｅ−Ｂ系永久磁石表面に、アルミニウム被膜を有し、前記アルミニウム被膜表面に、酸化被膜層を介して、ポリイミド樹脂被膜を有する永久磁石は、ポリイミド樹脂被膜が、酸化被膜層の存在によって、アルミニウム被膜表面に強固に密着しており、アルミニウム被膜とともに優れた耐食性・電気絶縁性・耐熱性を発揮する。また、酸化被膜層の上では、ポリイミド樹脂被膜形成反応が効率よく進行するので、溶液法によってもアルミニウム被膜表面に対して優れた密着性を有するポリイミド樹脂被膜を形成することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an R—Fe—B permanent magnet and a method for producing the same. More specifically, the present invention relates to an R—Fe—B permanent magnet that exhibits excellent corrosion resistance, electrical insulation, and heat resistance required for magnets used in automobile motors, and a simple manufacturing method thereof.
[0002]
[Prior art]
R-Fe-B permanent magnets typified by Fe-B-Nd permanent magnets are made of resource-rich and inexpensive materials and have high magnetic properties compared to Sm-Co permanent magnets. Therefore, it has been put to practical use in various applications.
However, since R-Fe-B permanent magnets contain highly reactive R and Fe, they are easily oxidatively corroded in the atmosphere, and when used without any surface treatment, a slight amount of acid or Corrosion progresses from the surface due to the presence of alkali, moisture, and the like, and rust is generated, which causes deterioration and variation in magnet characteristics. Furthermore, when a magnet in which rust is generated is incorporated in a device such as a magnetic circuit, the rust may be scattered to contaminate peripheral components.
[0003]
In view of the above points, in order to improve the corrosion resistance of R-Fe-B permanent magnets, a magnet having a corrosion-resistant metal plating film formed on a magnet surface by a wet plating method such as an electroless plating method or an electroplating method is provided. It has already been proposed (see Japanese Patent Publication No. 3-74012). However, in this method, an acidic solution or an alkaline solution used in the pretreatment of the plating treatment may remain in the magnet hole, and the magnet may corrode over time. Further, since the magnet is inferior in chemical resistance, the surface of the magnet may be corroded during the plating process. Furthermore, even when a metal plating film is formed on the magnet surface as described above, when a corrosion resistance test is performed under the conditions of a temperature of 60 ° C. and a relative humidity of 90%, the magnetic properties are 10% higher than the initial value after 100 hours. Deterioration may occur.
[0004]
Further, a method of forming an oxidation-resistant chemical conversion film such as a phosphate film or a chromate film on the surface of an R—Fe—B permanent magnet has also been proposed (see Japanese Patent Publication No. 4-22008). Although the film obtained by this method is excellent in terms of adhesion to the magnet, when a corrosion resistance test is performed under the conditions of a temperature of 60 ° C. and a relative humidity of 90%, the magnetic properties after 10 hours are 10% of the initial value. Deterioration may occur.
[0005]
Further, a method proposed in order to improve the corrosion resistance of the R—Fe—B permanent magnet, a method in which an aluminum film is formed by a vapor deposition method and then a chromate treatment, a so-called aluminum-chromate treatment method (Japanese Patent Publication No. 6). -66173) significantly improves the corrosion resistance of magnets. However, since the chromate treatment used in this method uses hexavalent chromium which is undesirable from the environment, the waste liquid treatment method is complicated. Moreover, since the film obtained by this method contains hexavalent chromium in a small amount, there is a concern about the influence on the human body when handling the magnet.
[0006]
[Problems to be solved by the invention]
On the other hand, R-Fe-B permanent magnets incorporated in automobile motors are required to have excellent performance in terms of electrical insulation and heat resistance as well as corrosion resistance. The treatment method cannot provide excellent electrical insulation and heat resistance.
Therefore, in the present invention, an R-Fe-B permanent magnet that exhibits excellent corrosion resistance, electrical insulation, and heat resistance required for magnets used in automobile motors, and a simple manufacturing method using a solution method. The purpose is to provide.
[0007]
[Means for Solving the Problems]
As a result of intensive studies in view of the above points, the present inventors formed an aluminum film on the surface of the R-Fe-B permanent magnet and formed a polyimide resin film thereon, in addition to excellent corrosion resistance. I came up with the idea of exhibiting excellent electrical insulation and heat resistance.
A technique for forming an aluminum film on the surface of an R—Fe—B permanent magnet and forming a polyimide resin film thereon has already been disclosed in JP-A-8-279407. However, the method for forming a polyimide resin film in this technique is to form a condensation type polyimide resin film by vapor deposition polymerization using two kinds of raw material monomers (aromatic carboxylic dianhydride and aromatic diamine). Although this technique is valuable as a method for forming a polyimide resin film having excellent performance on an aluminum film, a large-scale apparatus is required to perform the vapor deposition polymerization method. In addition, pretreatment such as cleaning must be performed strictly. Therefore, it causes an increase in manufacturing cost and is not necessarily satisfactory from the viewpoint of mass production.
[0008]
As a result of further intensive studies in view of the above points, the present inventors formed an oxide film layer on the surface of the aluminum film on the R-Fe-B permanent magnet, and formed a polyimide resin film thereon. It was found that due to the presence of the coating layer, the polyimide resin coating adhered firmly to the surface of the aluminum coating and exhibited excellent corrosion resistance, electrical insulation and heat resistance together with the aluminum coating. Further, it has been found that the polyimide resin film formation reaction proceeds efficiently on the oxide film layer, and a film having excellent adhesion to the aluminum film surface can be obtained by the solution method.
[0009]
The present invention has been made based on such knowledge, and the permanent magnet of the present invention has an aluminum coating on the surface of the R-Fe-B based permanent magnet as described in claim 1, Polyimide resin coating through the oxide coating layerAs addition type polyimide resin coatingIt is characterized by having.
MaClaim2The described permanent magnet is claimed1The permanent magnet described above is characterized in that the addition-type polyimide resin film is a film obtained from bisallylnadiimide.
Claims3The permanent magnet according to claim 1.Or 2The described permanent magnet is characterized in that the film thickness of the aluminum coating is 0.01 μm to 50 μm.
Claims4The permanent magnet according to claim 1 to claim 1.3In the permanent magnet according to any one of the above, the oxide film layer has a thickness of 0.01 μm to 2 μm.
Claims5The permanent magnet according to claim 1 to claim 1.4In the permanent magnet according to any one of the above, the film thickness of the polyimide resin film is 1 μm to 15 μm.
Further, the manufacturing method of the permanent magnet of the present invention is as follows.6As described, after forming an aluminum film on the surface of the R—Fe—B permanent magnet, an oxide film layer is formed on the surface of the aluminum film by an oxidation treatment in an oxygen atmosphere, and on the surface of the oxide film layer, A polyimide resin film is formed by applying a polyimide resin film forming treatment liquid and heat-treating it.
Claims7The manufacturing method according to claim6The manufacturing method described above is characterized in that an aluminum film is formed by a vapor phase growth method.
Claims8The manufacturing method according to claim7In the described manufacturing method, an aluminum film having a film thickness of 0.01 μm to 50 μm is formed.
Claims9The manufacturing method according to claim6In the described manufacturing method, an R-Fe-B permanent magnet and an aluminum piece are placed in a processing vessel, and both are vibrated and / or stirred in the processing vessel to form an aluminum coating. It is characterized by doing.
Claims10The manufacturing method according to claim9In the manufacturing method described above, an aluminum film having a film thickness of 0.01 μm to 1 μm is formed.
Claims11The manufacturing method according to claim6Thru10In the production method according to any one of the above, the oxidation treatment in an oxygen atmosphere is performed under normal pressure with an oxygen concentration of 0.01% to 20% or with an oxygen pressure (partial pressure) of 0.1 Pa to 2 × 104It is characterized by being carried out at 10 ° C. to 500 ° C. under a reduced pressure of Pa.
Claims12The manufacturing method according to claim6Thru11In the manufacturing method according to any one of the above, the polyimide resin film is an addition-type polyimide resin film.
Claims13The manufacturing method according to claim12In the production method described above, the addition-type polyimide resin film is a film obtained from bisallylnadiimide.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The permanent magnet of the present invention is characterized by having an aluminum film on the surface of the R-Fe-B permanent magnet and a polyimide resin film on the surface of the aluminum film via an oxide film layer.
[0011]
The method for forming the aluminum coating on the surface of the R—Fe—B permanent magnet is not particularly limited. However, considering that the magnet and the aluminum coating are susceptible to oxidative corrosion, the following method by vapor phase growth method, R-Fe-B permanent magnet and aluminum piece are placed in a processing vessel, Thus, a desirable method is a method in which both are vibrated and / or both are stirred.
[0012]
(1) Vapor growth method
Examples of the vapor phase growth method that can be employed for forming the aluminum coating include known methods such as vacuum deposition, ion sputtering, and ion plating. The aluminum film may be formed under the general conditions of each method, but vacuum deposition or ion plating is adopted from the viewpoint of the denseness of the film to be formed, film thickness uniformity, film formation speed, etc. It is desirable to do. Needless to say, the surface of the magnet may be subjected to a known cleaning treatment such as cleaning, degreasing, or sputtering before the coating is formed.
[0013]
It is desirable to set the temperature of the magnet at the time of film formation to 200 ° C to 500 ° C. If the temperature is less than 200 ° C., a film having excellent adhesion to the magnet surface may not be formed. If the temperature exceeds 500 ° C., cracks occur in the film during the cooling process after the film is formed. It is because there exists a possibility of peeling from.
[0014]
If the film thickness of the aluminum coating is less than 0.01 μm, excellent corrosion resistance may not be exhibited, and if it exceeds 50 μm, not only the manufacturing cost may be increased but also the effective volume of the magnet may be reduced. Therefore, 0.01 μm to 50 μm is desirable, but 0.05 μm to 25 μm is more desirable.
[0015]
(2) A method in which an R—Fe—B permanent magnet and an aluminum piece are placed in a processing vessel, and both are vibrated and / or stirred in the processing vessel. Aluminum piece used in the present method Can be used in various shapes such as needle shape (wire shape), columnar shape, and lump shape, but the end is sharp from the viewpoint of efficiently producing aluminum fine powder as a constituent source of the aluminum coating. It is desirable to use a needle or cylinder.
[0016]
The size (major axis) of the aluminum piece is preferably 0.05 mm to 10 mm, more preferably 0.3 mm to 5 mm, and still more preferably 0.5 mm to 0.5 mm, from the viewpoint of efficiently generating aluminum fine powder. 3 mm. Aluminum pieces having the same shape and the same size may be used, or those having different shapes and sizes may be mixed and used.
[0017]
The vibration and / or stirring for the magnet and the aluminum piece is preferably performed dry, taking into consideration that both are easily oxidized and corroded, and can be performed at room temperature in an air atmosphere. The processing container that can be used in the present invention does not need a complicated apparatus, and may be, for example, a processing chamber of a barrel apparatus. As the barrel device, known devices such as a rotary type, a vibration type, and a centrifugal type can be used. In the case of a rotary type, the number of rotations is desirably 20 rpm to 50 rpm. In the case of the vibration type, it is desirable that the vibration frequency is 50 Hz to 100 Hz and the vibration amplitude is 0.3 mm to 10 mm. In the case of the centrifugal type, the number of rotations is desirably 70 rpm to 200 rpm.
[0018]
As for the quantity of the magnet and aluminum piece put into a processing container, 20 vol%-90 vol% of the processing container internal volume are desirable. This is because if the amount is less than 20 vol%, the treatment amount is too small to be practical, and if it exceeds 90 vol%, a film may not be formed efficiently. Further, the ratio of the magnet and the aluminum piece placed in the processing container is preferably 3 or less in terms of volume ratio (magnet / aluminum piece). This is because if the volume ratio exceeds 3, it takes time to form the coating, which may be impractical. Moreover, although processing time is dependent also on processing amount, it is normally 1 hour-10 hours.
[0019]
By the above method, aluminum fine powder generated from the aluminum piece is deposited on the surface of the magnet to form an aluminum coating. The phenomenon that the aluminum fine powder adheres to the magnet surface is considered to be a kind of mechanochemical reaction, and the aluminum fine powder adheres firmly to the magnet surface, and the resulting aluminum coating exhibits excellent corrosion resistance. From the viewpoint of ensuring sufficient corrosion resistance, as described above, the film thickness is desirably 0.01 μm or more. The upper limit of the film thickness is not particularly limited, but it takes time to form an aluminum film having a film thickness exceeding 1 μm, so this method is suitable as a method for forming an aluminum film having a film thickness of 1 μm or less. Yes.
[0020]
As a pre-process for forming an oxide film layer on the surface of the aluminum film, shot peening (a method for modifying the surface by colliding hard particles) may be performed. By performing shot peening, the aluminum film is smoothed to improve the corrosion resistance of the aluminum film itself, and it is easy to form a uniform oxide film layer, and a polyimide resin film having excellent performance even in a thin film is formed. It can be made easier.
The powder used for shot peening is preferably one having a hardness equal to or higher than the hardness of the formed aluminum coating, and examples thereof include a spherical hard powder having a Mohs hardness of 3 or more, such as a steel ball or glass bead. When the average particle size of the powder is less than 30 μm, the pressing force against the aluminum coating is small, and processing takes time. On the other hand, if it exceeds 3000 μm, the surface roughness becomes too rough and the finished surface may be non-uniform. Therefore, the average particle size of the powder is desirably 30 μm to 3000 μm, and more desirably 40 μm to 2000 μm.
The injection pressure in shot peening is 1.0 kg / cm2~ 5.0kg / cm2Is desirable. Injection pressure is 1.0kg / cm2If the pressure is less than 5, the pressing force against the metal film is small, and it takes time to process, 5.0 kg / cm2This is because the pressing force on the metal film is not uniform and the surface roughness may be deteriorated.
The injection time in shot peening is preferably 1 minute to 1 hour. If the spraying time is less than 1 minute, the entire surface may not be uniformly treated, and if it exceeds 1 hour, the surface roughness may be deteriorated.
[0021]
The adhesion between the magnet surface and the aluminum coating can be improved by heat treatment after forming the aluminum coating on the magnet surface. If the temperature of the heat treatment is less than 200 ° C., the interface reaction between the magnet and the aluminum coating may not proceed sufficiently and adhesion may not be improved, and if it exceeds 500 ° C., the magnetic properties of the magnet may be deteriorated. The aluminum film may be dissolved. Therefore, the heat treatment is desirably performed at 200 ° C. to 500 ° C., but more desirably performed at 200 ° C. to 350 ° C. from the viewpoint of productivity and manufacturing cost. The same effect can be obtained by heat treatment after applying a polyimide resin film forming treatment liquid to the surface of the oxide film layer described later.
[0022]
Examples of the method for forming the oxide film layer on the surface of the aluminum film include an oxidation treatment method in an oxygen atmosphere and an oxidation treatment method (including a general water vapor treatment) in an atmosphere containing water vapor.
Examples of the oxidation treatment method in an oxygen atmosphere include a method in which the oxygen concentration and temperature are controlled in a treatment chamber and natural oxidation in the atmosphere. The treatment conditions include an oxygen concentration of 0.01% to 20% under normal pressure, or an oxygen pressure (partial pressure) of 0.1 Pa to 2 × 10.4It is desirable to carry out at 10 degreeC-500 degreeC under pressure reduction of Pa. The atmospheric pressure conditions with an oxygen concentration of 0.01% to 20% may be those utilizing the air itself, or adjusted to a desired component composition using an inert gas such as nitrogen gas or argon gas. It may be a thing. Oxygen pressure (partial pressure) is 0.1 Pa to 2 × 104The pressure reduction condition of Pa may be adjusted only by oxygen pressure, or may be adjusted to a desired component composition or pressure using an inert gas such as nitrogen gas or argon gas. . The reason why it is desirable to perform the oxidation treatment at 10 ° C. to 500 ° C. is that if it exceeds 500 ° C., the magnetic properties of the magnet may be deteriorated or the aluminum coating may be deformed. In addition, as the processing temperature increases, it becomes difficult to form a dense and thin oxide film layer, or the surface roughness of the oxide film layer becomes rough, which adversely affects the formation of the polyimide resin film. This is because a magnet having excellent performance such as corrosion resistance may not be obtained. The treatment time when the oxidation treatment is performed in the treatment chamber under the above treatment conditions is usually 5 minutes to 48 hours. As an oxidation treatment method in an oxygen atmosphere, in addition to the above-described methods, the above-described aluminum film surface shot peening, shot blast treatment, sputtering treatment under a weak voltage, or high-frequency oxygen plasma formation There are oxidation treatments.
The oxidation treatment method in an atmosphere containing water vapor (including general water vapor treatment) is performed while controlling the water vapor concentration and temperature. Specific treatment conditions include, for example, a water vapor concentration of 0.01. % To 100%, and the processing temperature is 10 ° C to 300 ° C.
[0023]
The film thickness of the oxide film layer formed by the above method is desirably 0.01 μm or more. It is because there exists a possibility that it may not contribute to the outstanding adhesiveness of the polyimide resin film to the aluminum film surface as a film thickness is less than 0.01 micrometer. On the other hand, the thickness of the oxide film layer is desirably 2 μm or less. This is because if the film thickness exceeds 2 μm, the excellent adhesion of the polyimide resin coating to the aluminum coating surface may be hindered. Furthermore, if the request based on the downsizing of the magnet itself is taken into consideration, the film thickness of the oxide film layer is more preferably 1 μm or less.
[0024]
Next, a method for forming a polyimide resin film on the surface of the oxide film layer will be described.
The polyimide resin film may be an addition-type polyimide resin film or a condensation-type polyimide resin film, but preferably an addition-type polyimide resin film. Addition-type polyimide resins have unsaturated groups at the end of resin molecules and are obtained by three-dimensional crosslinking by addition reaction or radical reaction. However, since no water is generated during curing, the magnet is subject to oxidative corrosion. Considering that it is easy to be done, it is a very convenient resin. As an addition type polyimide resin, a resin obtained from bisallylnadiimide (BANI: see FIG. 1), which is an imide monomer synthesized from allyl nadic acid anhydride and diamine and having an allyl group at both ends after completion of the dehydration ring closure reaction. In addition, known ones such as terminal nadic acid type polyimide resin (PMR), bismaleimide type polyimide resin, terminal acetylene type polyimide resin can be used.
[0025]
[Chemical 1]
Examples of the condensation type polyimide resin include a pyromellitic type polyimide resin obtained through a dehydration condensation reaction from pyromellitic dianhydride and 4,4'-diaminodiphenyl ether. Condensation-type polyimide resin generates water during curing, but the oxide film layer serves as a protective layer on the magnet surface, making it difficult for water to contact the magnet surface. It can be formed on the surface of the aluminum coating.
[0027]
The polyimide resin film can be formed on the surface of the oxide film layer by a method of applying a polyimide resin film forming treatment liquid to the surface of the oxide film layer and performing a heat treatment (so-called solution method) as compared with the vapor deposition polymerization method. This is desirable in that it can be mass-produced without increasing the manufacturing cost.
[0028]
The polyimide resin film forming treatment liquid may be prepared by dissolving the polyimide resin itself, a monomer or oligomer that is a raw material of the polyimide resin, in an organic solvent as necessary. For example, since bisallyl nadiimide is a low molecular weight imide monomer having a bulky structure, it is soluble in most organic solvents except aliphatic hydrocarbons and aliphatic alcohols. A solution for forming a pyromellitic polyimide resin film may be prepared, for example, by dissolving pyromellitic dianhydride and 4,4′-diaminodiphenyl ether in N-methyl-2-pyrrolidone as a highly polar solvent. That's fine.
[0029]
As a method for applying the polyimide resin film forming treatment liquid to the surface of the oxide film layer, a dip coating method, a spray method, a spin coating method, or the like can be used.
[0030]
The heat treatment after applying the polyimide resin film forming treatment liquid to the surface of the oxide film layer is desirably performed at 200 ° C to 400 ° C. This is because if it is less than 200 ° C., the curing reaction may not proceed sufficiently, and if it exceeds 400 ° C., the coating may be deteriorated. The heat treatment time is usually 5 minutes to 24 hours.
In addition, before performing heat processing, you may perform the drying process (For example, 60 minutes-90 degreeC conditions for 5 minutes-1 hour) before performing heat processing as needed.
[0031]
The formation of the polyimide resin film on the surface of the oxide film layer is not limited to the method of applying the polyimide resin film forming treatment liquid to the surface of the oxide film layer and performing a heat treatment, but may be performed by a vapor deposition polymerization method. For example, when a pyromellitic polyimide resin film is formed on the surface of the oxide film layer by vapor deposition polymerization, a magnet with an aluminum film having an oxide film layer on the surface is used at a degree of vacuum of 1 Pa to 10 Pa.-3It is housed in a Pa vacuum vessel, pyromellitic dianhydride and 4,4′-diaminodiphenyl ether are heated and deposited at 200 ° C. to 250 ° C. to form a polyamic acid film, and then under normal pressure, 280 ° C. to 380 ° C. (See JP-A-8-279407).
[0032]
Since the polyimide resin film formed by the above method is firmly adhered to the surface of the aluminum film through the oxide film layer, excellent performance such as corrosion resistance is exhibited when the film thickness is 1 μm or more. Although the upper limit of the film thickness of the polyimide resin coating is not limited, it is preferably 15 μm or less and more preferably 10 μm or less because of demands based on miniaturization of the magnet itself. It goes without saying that the application of the polyimide resin film forming treatment liquid to the surface of the oxide film layer and the subsequent heat treatment may be repeated a plurality of times as necessary.
Furthermore, in order to improve various performances of the polyimide resin coating (such as wear resistance and slipperiness), fine particles of metals such as titanium and nickel, fine particles of ceramics such as alumina and silica, and metal oxides, Teflon In addition, various fine particles used as organic pigments and inorganic pigments may be dispersed. For example, if a Teflon sphere having a particle diameter of 1 μm is dispersed in the coating by about 20% by weight, the slipping property of the polyimide resin coating can be improved. The size and shape of the fine particles to be added are appropriately selected in consideration of the performance and film thickness of the coating film to be formed. Usually, fine particles having a particle diameter of 0.01 μm to 5 μm can be used.
[0033]
The rare earth element (R) in the R—Fe—B permanent magnet used in the present invention is at least one of Nd, Pr, Dy, Ho, Tb, Sm, or La, Ce, Gd, Er, Eu. , Tm, Yb, Lu, and Y are preferred.
Usually, one type of R is sufficient, but in practice, a mixture of two or more types (such as misch metal and didymium) can also be used for reasons of convenience.
If the content of R in the R—Fe—B permanent magnet is less than 10 atomic%, the crystal structure is a cubic structure having the same structure as α-Fe, so that high magnetic properties, particularly high coercive force (HcJ) are obtained. On the other hand, if it exceeds 30 atomic%, the R-rich non-magnetic phase increases, the residual magnetic flux density (Br) decreases, and a permanent magnet with excellent characteristics cannot be obtained. It is desirable to be 30 atomic%.
[0034]
When the Fe content is less than 65 atomic%, Br decreases, and when it exceeds 80 atomic%, high HcJ cannot be obtained. Therefore, the content of 65 atomic% to 80 atomic% is desirable.
In addition, by replacing part of Fe with Co, the temperature characteristics can be improved without impairing the magnetic characteristics of the obtained magnet. However, when the Co substitution amount exceeds 20 atomic%, the magnetic characteristics are reduced. Undesirable because it deteriorates. When the amount of Co substitution is 5 atom% to 15 atom%, Br increases as compared with the case where it is not substituted, and thus it is desirable for obtaining a high magnetic flux density.
[0035]
When the content of B is less than 2 atomic%, the rhombohedral structure becomes the main phase, and high HcJ cannot be obtained. When it exceeds 28 atomic%, the B-rich nonmagnetic phase increases, and the Br decreases and is excellent. Since a permanent magnet having the characteristics cannot be obtained, the content is preferably 2 atomic% to 28 atomic%.
Moreover, in order to improve the manufacturability and reduce the price of the magnet, at least one of 2.0 wt% or less P and 2.0 wt% or less S is contained in a total amount of 2.0 wt% or less. May be. Furthermore, the corrosion resistance of the magnet can be improved by replacing a part of B with C of 30 wt% or less.
[0036]
Furthermore, at least one of Al, Ti, V, Cr, Mn, Bi, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr, Ni, Si, Zn, Hf, and Ga is added. It is effective in improving the squareness of the demagnetization curve, improving manufacturability, and reducing the price. The amount of addition is such that the maximum energy product (BH) max is 159 kJ / m.3In order to achieve the above, Br needs to be at least 0.9 T or more, so it is desirable to add it in a range that satisfies this condition.
The R—Fe—B permanent magnet may contain impurities inevitable for industrial production in addition to R, Fe, and B.
[0037]
Further, among the R—Fe—B permanent magnets used in the present invention, a compound having a tetragonal crystal structure having an average crystal grain size in the range of 1 μm to 80 μm is a main phase, and the volume ratio is 1%. Magnets containing ˜50% non-magnetic phase (excluding oxide phase) have HcJ ≧ 80 kA / m, Br> 0.4T, (BH) max ≧ 80 kJ / m3The maximum value of (BH) max is 199 kJ / m3Reach above.
[0038]
In addition, you may laminate | stack another film on the polyimide resin film of this invention. By employ | adopting such a structure, the characteristic of a polyimide resin film can be strengthened and supplemented, or the further functionality can be provided.
[0039]
【Example】
For example, as described in U.S. Pat. No. 4,770,723, 17Nd-1Pr-75Fe-7B obtained by pulverizing a known cast ingot and finely pulverizing, molding, sintering, heat treatment, and surface treatment. The following experiment was performed using a sintered magnet having a composition of 23 mm × 10 mm × 6 mm (hereinafter referred to as “magnet body test piece”). In the following experiments, the film thickness of the aluminum film, the film thickness of the oxide film layer, and the film thickness of the polyimide resin film were measured by electron microscope observation of the fracture surface.
The present invention is not limited to application to R—Fe—B based sintered magnets, but can also be applied to R—Fe—B based bonded magnets.
[0040]
Experimental example 1:
A magnet specimen is accommodated in a vacuum vessel, and the inside is 1 × 10-4After evacuating to Pa or lower, sputtering was performed for 15 minutes under the conditions of Ar gas pressure of 10 Pa and bias voltage of −400 V to clean the magnet surface.
Next, under conditions of Ar gas pressure of 10 Pa, bias voltage of −50 V, and magnet temperature of 250 ° C., metal aluminum was used as a target, arc ion plating was performed for 20 minutes, an aluminum film was formed on the magnet surface, and then allowed to cool. . The film thickness of the obtained aluminum coating was 1.1 μm.
The aluminum-coated magnet obtained by the above method is immediately accommodated in a processing chamber and subjected to an oxidation treatment at a temperature of 200 ° C. for 10 minutes under an atmospheric pressure with an oxygen concentration of 5% (for details, see Table 1). An oxide film layer was formed on the substrate. The thickness of the formed oxide film layer was 0.3 μm.
A solution obtained by diluting BANI-M (trade name, manufactured by Maruzen Petrochemical Co., Ltd.) to 20% (vol / vol) using toluene as an organic solvent as a polyimide resin film forming treatment liquid was prepared. This was applied by spraying to an aluminum-coated magnet having an oxide film layer on the surface obtained by the above method. Subsequently, after drying at 80 ° C. for 10 minutes, a heat treatment was performed at 250 ° C. for 15 minutes to form a polyimide resin film on the surface of the oxide film layer. The film thickness of the formed polyimide resin film was 5 μm.
The magnet obtained by the above method having an aluminum coating on the surface, and a magnet having a polyimide resin coating on the surface of the aluminum coating through an oxide coating layer, is subjected to a high temperature and high humidity condition of a temperature of 70 ° C. and a relative humidity of 90%. The corrosion resistance acceleration test was conducted by leaving it underneath. As a result, no rusting or film peeling was observed even after 500 hours from the start of the test, and excellent corrosion resistance was exhibited.
Moreover, when the electrical insulation was evaluated by the volume resistivity (ρ), 1 × 1015An excellent value of Ω · cm or more was exhibited. The volume resistivity was determined from the equation of ρ = R · S / l by attaching the electrode to the sample and measuring the resistance between the coating surface and the magnet (R: resistance (Ω), S: electrode area ( cm2), L: polyimide resin film thickness (cm)). When the heat resistance was evaluated by the heat distortion temperature, an excellent value of 280 ° C. or higher was shown. The thermal deformation temperature was a temperature at which the film was left at that temperature for 20 hours in the atmosphere to cause discoloration or cracking of the coating.
[0041]
Experimental example 2:
In Experimental Example 1, a polyimide resin film having a film thickness of 10 μm was formed under the same conditions as in Experimental Example 1 except that the heat treatment was performed after the application and drying by the spray method were repeated once again.
A corrosion resistance acceleration test under the same conditions as in Experimental Example 1 was performed on a magnet having an aluminum film on the surface obtained by the above method and having a polyimide resin film on the surface of the aluminum film via an oxide film layer. It was. As a result, no rusting or film peeling was observed even after 500 hours from the start of the test, and excellent corrosion resistance was exhibited. Moreover, when the electrical insulation was evaluated by the volume resistivity (ρ), 1 × 1015An excellent value of Ω · cm or more was exhibited. When the heat resistance was evaluated by the heat distortion temperature, an excellent value of 280 ° C. or higher was shown.
[0042]
Experimental Example 3:
Sputtering was performed on the magnet test piece under the same conditions as in Experimental Example 1 to clean the magnet surface. Next, under the conditions of Ar gas pressure of 1 Pa and voltage of 1.5 KV, an aluminum wire is used as a coating material, this is heated and evaporated to ionize, ion plating is performed for 2.5 minutes, and an aluminum coating is formed on the magnet surface. Formed and allowed to cool. The film thickness of the obtained aluminum coating was 2 μm.
Then N2A spherical glass bead powder having an average particle size of 120 μm and a Mohs hardness of 6 together with a pressurized gas composed of a gas, an injection pressure of 1.5 kg / cm2Was shot on the surface of the aluminum coating for 10 minutes to give shot peening.
The aluminum-coated magnet obtained by the above method was immediately accommodated in a processing chamber, and subjected to an oxidation treatment at a temperature of 250 ° C. for 7 minutes under normal pressure with an oxygen concentration of 0.1% (for details, see Table 1). An oxide coating layer was formed on the coating surface. The thickness of the formed oxide film layer was 0.2 μm.
For the aluminum-coated magnet having an oxide film layer on the surface obtained by the above method, using the same polyimide resin film forming treatment liquid as used in Experimental Example 1, under the same conditions as in Experimental Example 1, A polyimide resin film having a thickness of 5 μm was formed.
A corrosion resistance acceleration test under the same conditions as in Experimental Example 1 was performed on a magnet having an aluminum film on the surface obtained by the above method and having a polyimide resin film on the surface of the aluminum film via an oxide film layer. It was. As a result, no rusting or film peeling was observed even after 500 hours from the start of the test, and excellent corrosion resistance was exhibited. Moreover, when the electrical insulation was evaluated by the volume resistivity (ρ), 1 × 1015An excellent value of Ω · cm or more was exhibited. When the heat resistance was evaluated by the heat distortion temperature, an excellent value of 280 ° C. or higher was shown.
[0043]
Experimental Example 4:
In Experimental Example 3, a polyimide resin film having a film thickness of 10 μm was formed under the same conditions as in Experimental Example 3, except that heat treatment was performed after applying and drying by the spray method once again.
A corrosion resistance acceleration test under the same conditions as in Experimental Example 1 was performed on a magnet having an aluminum film on the surface obtained by the above method and having a polyimide resin film on the surface of the aluminum film via an oxide film layer. It was. As a result, no rusting or film peeling was observed even after 500 hours from the start of the test, and excellent corrosion resistance was exhibited. Moreover, when the electrical insulation was evaluated by the volume resistivity (ρ), 1 × 1015An excellent value of Ω · cm or more was exhibited. When the heat resistance was evaluated by the heat distortion temperature, an excellent value of 280 ° C. or higher was shown.
[0044]
Experimental Example 5:
100 magnet test pieces (apparent capacity 0.35 liters, weight 1.1 kg) and short cylindrical aluminum pieces (diameter 0.8 mm, length 1 mm) (apparent capacity 20 liters, weight 100 kg) with a vibration volume of 50 liters Put into the processing chamber of the barrel device (total input is 30 vol% of the processing chamber volume) and dry-process for 7 hours under conditions of vibration frequency 60Hz and vibration amplitude 1.8mm to form an aluminum coating on the magnet surface did. The film thickness of the obtained aluminum coating was 0.2 μm.
The aluminum-coated magnet obtained by the above method was immediately accommodated in a processing chamber, and oxidized at a temperature of 180 ° C. for 6 minutes under normal pressure with an oxygen concentration of 0.2% (see Table 1 for details). An oxide coating layer was formed on the coating surface. The thickness of the formed oxide film layer was 0.1 μm.
For the aluminum-coated magnet having an oxide film layer on the surface obtained by the above method, using the same polyimide resin film forming treatment liquid as used in Experimental Example 1, under the same conditions as in Experimental Example 1, A polyimide resin film having a thickness of 5 μm was formed.
A corrosion resistance acceleration test under the same conditions as in Experimental Example 1 was performed on a magnet having an aluminum film on the surface obtained by the above method and having a polyimide resin film on the surface of the aluminum film via an oxide film layer. It was. As a result, no rusting or film peeling was observed even after 500 hours from the start of the test, and excellent corrosion resistance was exhibited. Moreover, when the electrical insulation was evaluated by the volume resistivity (ρ), 1 × 1015An excellent value of Ω · cm or more was exhibited. When the heat resistance was evaluated by the heat distortion temperature, an excellent value of 280 ° C. or higher was shown.
[0045]
Experimental Example 6:
An aluminum-coated magnet having a film thickness of 1.1 μm obtained by the same method as in Experimental Example 1 was immediately accommodated in a processing chamber, and under a reduced pressure of 10 Pa oxygen (see Table 1 for details), a temperature of 220 ° C. and 15 A partial oxidation treatment was performed to form an oxide film layer on the surface of the aluminum film. The thickness of the formed oxide film layer was 0.6 μm.
For the aluminum-coated magnet having an oxide film layer on the surface obtained by the above method, using the same polyimide resin film forming treatment liquid as used in Experimental Example 1, under the same conditions as in Experimental Example 1, A polyimide resin film having a thickness of 5 μm was formed.
A corrosion resistance acceleration test under the same conditions as in Experimental Example 1 was performed on a magnet having an aluminum film on the surface obtained by the above method and having a polyimide resin film on the surface of the aluminum film via an oxide film layer. It was. As a result, no rusting or film peeling was observed even after 500 hours from the start of the test, and excellent corrosion resistance was exhibited. Moreover, when the electrical insulation was evaluated by the volume resistivity (ρ), 1 × 1015An excellent value of Ω · cm or more was exhibited. When the heat resistance was evaluated by the heat distortion temperature, an excellent value of 280 ° C. or higher was shown.
[0046]
[Table 1]
Comparative Example 1:
Sputtering was performed on the magnet test piece under the same conditions as in Experimental Example 1 to clean the magnet surface. Next, arc ion plating was performed under the same conditions as in Experimental Example 1 to form an aluminum coating on the magnet surface and allowed to cool. The film thickness of the obtained aluminum coating was 1.5 μm. Next, a polyimide resin film having a film thickness of 5 μm was used under the same conditions as in Experimental Example 1, using the same polyimide resin film forming treatment liquid as used in Experimental Example 1 without forming an oxide film layer on the surface of the aluminum film. A resin coating was formed directly.
A corrosion resistance acceleration test under the same conditions as in Experimental Example 1 was performed on the magnet obtained by the above method, having an aluminum coating on the surface and having a polyimide resin coating directly on the aluminum coating surface. As a result, film peeling was observed 150 hours after the start of the test.
[0048]
Comparative Example 2:
In Comparative Example 1, a polyimide resin film having a film thickness of 10 μm was formed under the same conditions as in the Comparative Example except that the heat treatment was performed after the application and drying by the spray method were repeated once more.
A corrosion resistance acceleration test under the same conditions as in Experimental Example 1 was performed on the magnet obtained by the above method, having an aluminum coating on the surface and having a polyimide resin coating directly on the aluminum coating surface. As a result, film peeling was observed 250 hours after the start of the test.
[0049]
Experimental Example 7 to Experimental Example 12:
After forming an aluminum film on the surface of the magnet body test piece under the same conditions as in Experimental Examples 1 to 6, and after forming an oxide film layer on the surface, the polyimide resin film forming treatment liquid in each Experimental Example was prepared. A polyimide resin film is formed on the surface of the oxide film layer under the same conditions and thickness as in each experimental example, except that a mixed solvent of toluene, ethyl acetate and cyclohexanone (volume ratio 65:15:20) is used instead of the used toluene. did. Each sample was subjected to the same corrosion resistance acceleration test, electrical insulation evaluation, and heat resistance evaluation as those of Experimental Example 1, and all the samples showed the same results as the samples of each experimental example.
[0050]
【The invention's effect】
The permanent magnet which has an aluminum film on the surface of the R-Fe-B permanent magnet of the present invention and has a polyimide resin film on the surface of the aluminum film via an oxide film layer, the polyimide resin film is an oxide film layer. Due to the presence of aluminum, it is firmly adhered to the surface of the aluminum coating and exhibits excellent corrosion resistance, electrical insulation and heat resistance together with the aluminum coating. Moreover, since the polyimide resin film formation reaction proceeds efficiently on the oxide film layer, a polyimide resin film having excellent adhesion to the aluminum film surface can be formed even by a solution method.
Claims (13)
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| JP4747462B2 (en) * | 2001-08-10 | 2011-08-17 | 日立金属株式会社 | Method for producing rare earth-based permanent magnet having deposited film on surface |
| KR100746897B1 (en) * | 2001-12-28 | 2007-08-07 | 신에쓰 가가꾸 고교 가부시끼가이샤 | Rare earth element sintered magnet and method for producing rare earth element sintered magnet |
| JP5326730B2 (en) * | 2009-03-26 | 2013-10-30 | 日立金属株式会社 | Method for producing rare earth permanent magnets with excellent salt water resistance |
| JP5223761B2 (en) * | 2009-04-08 | 2013-06-26 | 日立金属株式会社 | Method for improving salt water resistance of rare earth permanent magnets with Al film containing Mg deposited on the surface |
| CN102041506A (en) * | 2009-10-13 | 2011-05-04 | 北京中科三环高技术股份有限公司 | Surface treatment method of permanent magnet material |
| US20130070402A1 (en) * | 2010-06-25 | 2013-03-21 | Nec Corporation | Communication device and producing method for enclosure of the same |
| JP5953059B2 (en) * | 2012-02-07 | 2016-07-13 | Ｋｙｂ株式会社 | Electric motor |
| JP7547815B2 (en) | 2020-07-07 | 2024-09-10 | 株式会社レゾナック | Molded member and actuator |
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| JPH08279407A (en) * | 1995-02-07 | 1996-10-22 | Sumitomo Special Metals Co Ltd | R-fe-b permanent magnet being excellent in electrical insulating properties, heat resistance and corrosion resistance and manufacture thereof |
| JPH09246027A (en) * | 1996-03-08 | 1997-09-19 | Sumitomo Special Metals Co Ltd | R-fe-b based permanent magnet excellent in resistance to salt water |
| JPH10340823A (en) * | 1997-06-05 | 1998-12-22 | Sumitomo Special Metals Co Ltd | Manufacture of r-iron-boron permanent magnet having excellent salt water resistance |
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| JPH09111182A (en) * | 1995-10-23 | 1997-04-28 | Daido Steel Co Ltd | Electronic part coated with insulating film and method of coating thereof |
| JPH10326552A (en) * | 1997-05-26 | 1998-12-08 | Matsushita Electric Works Ltd | Surface treatment film for high withstand voltage, and relay iron core provided with this film |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH08279407A (en) * | 1995-02-07 | 1996-10-22 | Sumitomo Special Metals Co Ltd | R-fe-b permanent magnet being excellent in electrical insulating properties, heat resistance and corrosion resistance and manufacture thereof |
| JPH09246027A (en) * | 1996-03-08 | 1997-09-19 | Sumitomo Special Metals Co Ltd | R-fe-b based permanent magnet excellent in resistance to salt water |
| JPH10340823A (en) * | 1997-06-05 | 1998-12-22 | Sumitomo Special Metals Co Ltd | Manufacture of r-iron-boron permanent magnet having excellent salt water resistance |
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