JP2009099853A - Highly corrosion-resistant r-t-b based rare earth magnet - Google Patents
Highly corrosion-resistant r-t-b based rare earth magnet Download PDFInfo
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 43
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 36
- 238000005260 corrosion Methods 0.000 title claims abstract description 32
- 230000007797 corrosion Effects 0.000 title claims abstract description 31
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 45
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 42
- 238000000576 coating method Methods 0.000 claims abstract description 25
- 239000011248 coating agent Substances 0.000 claims abstract description 21
- 229910052742 iron Inorganic materials 0.000 claims abstract description 12
- 238000007747 plating Methods 0.000 claims description 56
- 230000003647 oxidation Effects 0.000 claims description 11
- 238000007254 oxidation reaction Methods 0.000 claims description 11
- 230000001590 oxidative effect Effects 0.000 claims description 5
- 229910001593 boehmite Inorganic materials 0.000 claims description 4
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical group O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 2
- MXRIRQGCELJRSN-UHFFFAOYSA-N O.O.O.[Al] Chemical compound O.O.O.[Al] MXRIRQGCELJRSN-UHFFFAOYSA-N 0.000 claims description 2
- 238000007743 anodising Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000002048 anodisation reaction Methods 0.000 abstract description 5
- 238000009713 electroplating Methods 0.000 abstract description 2
- 238000004381 surface treatment Methods 0.000 abstract 2
- 239000003125 aqueous solvent Substances 0.000 abstract 1
- 239000010408 film Substances 0.000 description 60
- 239000000463 material Substances 0.000 description 14
- 238000000034 method Methods 0.000 description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 150000003839 salts Chemical class 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- 239000007921 spray Substances 0.000 description 10
- 239000007864 aqueous solution Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 230000033444 hydroxylation Effects 0.000 description 7
- 238000005805 hydroxylation reaction Methods 0.000 description 7
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 238000007740 vapor deposition Methods 0.000 description 4
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 230000005347 demagnetization Effects 0.000 description 3
- 238000004070 electrodeposition Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 235000010344 sodium nitrate Nutrition 0.000 description 2
- 239000004317 sodium nitrate Substances 0.000 description 2
- HHVIBTZHLRERCL-UHFFFAOYSA-N sulfonyldimethane Chemical compound CS(C)(=O)=O HHVIBTZHLRERCL-UHFFFAOYSA-N 0.000 description 2
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000004962 Polyamide-imide Substances 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 125000005234 alkyl aluminium group Chemical group 0.000 description 1
- -1 aluminum halide Chemical class 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000003925 fat Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229920002312 polyamide-imide Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 239000009719 polyimide resin Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 238000007751 thermal spraying Methods 0.000 description 1
- 238000004506 ultrasonic cleaning Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- Powder Metallurgy (AREA)
- Hard Magnetic Materials (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
Description
R-T-B系希土類磁石に高耐食被膜を形成してなる高耐食性R-T-B系希土類磁石に関する。 The present invention relates to a high corrosion resistance R-T-B rare earth magnet obtained by forming a high corrosion resistance coating on an R-T-B rare earth magnet.
希土類磁石の中でもR-T-B系希土類磁石（ＲはＹを含む希土類元素の少なくとも１種である）は特に錆びやすいため、表面には各種めっきや樹脂塗装が施されている。耐食コーティングとして主に使用されているのは特許文献１に代表されるNiめっきであり、Ni/Niの２層めっき、Ni/Cu/Niの３層めっき、更にNi/Ni/Niの３層めっきなどが実用化されている。特許文献２には、R-T-B系希土類磁石の表面に化成処理を行い、更に樹脂塗装することによって耐食性を向上した希土類磁石が開示されている。また、気相蒸着法を用いたR-T-B系希土類磁石表面のコーティングも検討されており、特許文献３では気相蒸着法によって生成した下地金属被膜上に多官能エポキシ樹脂、ポリイミド樹脂またはポリアミドイミド樹脂を被覆する手法が記載されている。また、特許文献４では希土類磁石表面にアルミニウムを蒸着し、更にアルミニウム表面を化成処理して耐食性を向上させる方法が記載されている。
前記Ni、及びCuの多層めっき膜は耐食性に優れていることから、希土類磁石表面の耐食コーティングとして広く適用されている。ところが、これらのめっきにおいては、めっき液として水溶液を使用するためめっき中に水の電気分解が生じ、それによって発生した水素を磁石が吸蔵して脆化する。この水素脆化は磁気特性を悪化させることが知られている。また、海岸付近の極めて錆びやすい環境下においてはNi、Cu及びこれらの複合めっき膜でも耐食性は充分ではなく、錆の発生により磁気特性が劣化することが知られている。 Since the Ni and Cu multilayer plating films are excellent in corrosion resistance, they are widely applied as corrosion resistant coatings on the surface of rare earth magnets. However, in these platings, since an aqueous solution is used as a plating solution, water is electrolyzed during plating, and hydrogen generated thereby is occluded by the magnet and becomes brittle. This hydrogen embrittlement is known to deteriorate magnetic properties. Further, in an environment where rust is likely to rust near the coast, even Ni, Cu and these composite plating films are not sufficient in corrosion resistance, and it is known that magnetic properties deteriorate due to the generation of rust.
気相蒸着法においては水素吸蔵の影響がないものの、厚膜化が困難であり、充分な耐食性を持つ被膜を得るには時間がかかる。耐食性向上のため蒸着皮膜には化成処理などが行われているが、海岸付近で使用するには充分な耐食性が得られていない。また、ドライプロセスとウェットプロセスの組み合わせとなるため作業性が悪化してコスト高になる。 Although there is no influence of hydrogen occlusion in the vapor deposition method, it is difficult to increase the film thickness, and it takes time to obtain a film having sufficient corrosion resistance. In order to improve the corrosion resistance, the deposited film is subjected to a chemical conversion treatment or the like, but sufficient corrosion resistance is not obtained for use near the coast. Moreover, since it is a combination of a dry process and a wet process, workability deteriorates and costs increase.
本特許では、R-T-B系希土類磁石上に、高耐食性を有し且つめっき中に発生する水素ガス吸蔵により磁気特性が劣化しない被膜を有する高耐食性R-T-B系希土類磁石を提供することを目的とする。 An object of the present patent is to provide a highly corrosion-resistant R-T-B rare earth magnet having a coating on an R-T-B rare earth magnet that has high corrosion resistance and does not deteriorate in magnetic properties due to occlusion of hydrogen gas generated during plating.
アルミニウムのコーティング方法としては、溶融めっき、拡散浸透めっき、溶射などがあるが、いずれも膜厚制御が困難であり、高い寸法精度が要求される用途には不向きである。更にこれらのコーティング方法においては、処理温度が700℃近い高温となるため、磁気特性に悪影響を及ぼす恐れがある。別の成膜方法としてはPVDやCVDなどの蒸着がよく知られているが、成膜速度が遅いため十分な耐食性をもつ厚さの膜を形成するには長時間の処理を必要とする。 Examples of aluminum coating methods include hot dipping, diffusion penetration plating, and thermal spraying, but all of them are difficult to control the film thickness and are not suitable for applications requiring high dimensional accuracy. Furthermore, in these coating methods, the processing temperature is as high as close to 700 ° C., which may adversely affect the magnetic properties. As another film forming method, vapor deposition such as PVD and CVD is well known. However, since the film forming speed is slow, it takes a long time to form a film having a sufficient corrosion resistance.
一方、実用化された例は少ないものの低温で短時間にアルミニウムを成膜する方法として電気アルミニウムめっき法がある。電気アルミニウムめっき法は、めっき膜に環境および人体に影響を与える重金属を含まないことから、古くから研究が行われている。水溶液中におけるアルミニウム電析の電位は水素発生の電位よりも卑であるため、水溶液を用いてめっきを行う場合、アルミニウムの電析より先に水の電気分解が生じる。従って、水溶液による電気アルミニウムめっきは不可能とされており、溶媒にはテトラヒドロフラン、ジエチルエーテル、トルエン等の非水溶媒が使用されている。アルミニウム源となる溶質には、アルミニウムハロゲン化物やアルキルアルミニウムが用いられる。これらの溶質は水分と反応しやすく、空気中の水分を容易に吸収するため、電気アルミニウムめっきでは雰囲気の制御が重要である。 On the other hand, although there are few examples of practical use, there is an electroaluminum plating method as a method for forming an aluminum film in a short time at a low temperature. The electroaluminum plating method has been studied for a long time since the plating film does not contain heavy metals that affect the environment and the human body. Since the potential of aluminum electrodeposition in an aqueous solution is lower than the potential of hydrogen generation, when plating is performed using an aqueous solution, electrolysis of water occurs prior to aluminum electrodeposition. Therefore, electroaluminum plating with an aqueous solution is impossible, and nonaqueous solvents such as tetrahydrofuran, diethyl ether, and toluene are used as the solvent. An aluminum halide or alkylaluminum is used as a solute serving as an aluminum source. Since these solutes easily react with moisture and easily absorb moisture in the air, it is important to control the atmosphere in electroaluminum plating.
アルミニウムの表面は、熱水酸化、陽極酸化することで高耐食性を持つ被膜とすることができる。また、陽極酸化後に着色を行うことで、様々な外観を持つ被膜を形成することができる。 The surface of aluminum can be formed into a film having high corrosion resistance by thermal hydroxylation and anodization. Moreover, the film which has various external appearances can be formed by coloring after anodization.
本発明では、めっき液として非水溶媒を使用する電気アルミニウムめっきを行うことで上記課題を解決した。電気アルミニウムめっきはめっき液溶媒として有機溶剤や溶融塩を使用するため、水溶液のめっき液に比べて電気分解による水素発生が極めて少ない。従って、磁石にめっきを行う場合、水素吸蔵による磁気特性の劣化が少ないと考えられる。また、アルミニウムはR-T-B系希土類磁石よりも電気化学的に卑であり、被膜が傷ついた場合でも犠牲防食作用が働き磁石素材を酸化させないため、酸化による磁気特性の劣化も少ない。 In this invention, the said subject was solved by performing the electroaluminum plating which uses a nonaqueous solvent as a plating solution. Electro-aluminum plating uses an organic solvent or a molten salt as a plating solution solvent, so that hydrogen generation by electrolysis is extremely less than that of an aqueous solution. Therefore, when plating a magnet, it is considered that there is little deterioration in magnetic properties due to hydrogen storage. In addition, aluminum is electrochemically lower than R-T-B rare earth magnets, and even when the coating is damaged, the sacrificial anticorrosive action works and does not oxidize the magnet material, so there is little deterioration in magnetic properties due to oxidation.
すなわち本願第一の発明は、R-T-B系希土類焼結磁石（ＲはＹを含む希土類元素の少なくとも１種であり、ＴはFeまたはFe及びCoである）と、該R-T-B系希土類焼結磁石上に形成した電気アルミニウムめっき皮膜と、該電気アルミニウムめっき皮膜の一部を酸化させて形成した耐酸化層とを有することを特徴とする高耐食性R-T-B系希土類焼結磁石である。 That is, the first invention of the present application relates to an RTB rare earth sintered magnet (R is at least one kind of rare earth element including Y, T is Fe or Fe and Co), and an RTB rare earth sintered magnet on the RTB rare earth sintered magnet. A highly corrosion-resistant RTB-based rare earth sintered magnet having a formed electroaluminum plating film and an oxidation-resistant layer formed by oxidizing a part of the electroaluminum plating film.
本願第二の発明は、R-T-B系希土類磁石（ＲはＹを含む希土類元素の少なくとも１種であり、ＴはFeまたはFe及びCoである）の表面に電気アルミニウムめっきによりアルミニウム被膜を形成し、更にアルミニウム被膜の一部を酸化させ耐酸化層とする高耐食性R-T-B系希土類磁石の製造方法である。 In the second invention of the present application, an aluminum film is formed by electroaluminum plating on the surface of an RTB rare earth magnet (R is at least one rare earth element including Y, and T is Fe or Fe and Co). This is a method for producing a highly corrosion-resistant RTB rare earth magnet in which an aluminum coating is partially oxidized to form an oxidation resistant layer.
アルミニウムめっき膜厚は10〜100μｍであることが好ましい。膜厚が10μｍ未満になると、アルミニウムめっき膜のピンホールが顕著となり、表面を酸化させる際に磁石素地を侵食する恐れがある。また、膜厚が100μｍを超えると試料エッジにおける瘤状電析が顕著となる。 The aluminum plating film thickness is preferably 10 to 100 μm. When the film thickness is less than 10 μm, pinholes in the aluminum plating film become prominent, and there is a risk of eroding the magnet substrate when the surface is oxidized. Further, when the film thickness exceeds 100 μm, the nodule electrodeposition on the sample edge becomes remarkable.
アルミニウムめっき膜表面の酸化方法としては、陽極酸化及び熱水酸化が適している。陽極酸化では電極と被めっき物とを接触させるため被めっき物に接点痕ができる。接点痕を残さないためには熱水酸化が好ましい。熱水酸化の際には、トリエタノールアミンなどの被膜促進剤を使用することができる。アルミニウム酸化膜の厚さは100ｎｍ以上が好ましい。100ｎｍ未満では残留したアルミニウムめっき膜が酸化し、外観にムラを生じやすくなる。また、酸化膜の厚膜化の際にはアルミニウム被膜が残存している必要がある。アルミニウム被膜のすべてを酸化被膜とした場合、アルミニウム膜の薄い部分で素地の酸化が開始する恐れがあるからである。 Anodizing and thermal hydroxylation are suitable as the method for oxidizing the surface of the aluminum plating film. In anodic oxidation, the electrode and the object to be plated are brought into contact with each other, so that contact marks are formed on the object to be plated. Thermal hydroxylation is preferred in order not to leave contact marks. In the case of thermal hydroxylation, a film accelerator such as triethanolamine can be used. The thickness of the aluminum oxide film is preferably 100 nm or more. If the thickness is less than 100 nm, the remaining aluminum plating film is oxidized, and uneven appearance tends to occur. Further, it is necessary that the aluminum coating remains when the oxide film is thickened. This is because if the entire aluminum film is an oxide film, the substrate may be oxidized at a thin portion of the aluminum film.
本発明を用いれば、R-T-B希土類焼結磁石上に耐食性が良く、且つ磁力の低下が少ない被膜を得ることができる。 By using the present invention, it is possible to obtain a coating film having good corrosion resistance and little decrease in magnetic force on the R-T-B rare earth sintered magnet.
本発明のR-T-B系希土類焼結磁石用高耐食コーティングについて、その一例を以下に述べる。なお、電気アルミニウムめっき液は実施例に記載のものに限らず、どのようなめっき液でも適用可能である。 An example of the high corrosion resistance coating for R-T-B rare earth sintered magnets of the present invention will be described below. The electrolytic aluminum plating solution is not limited to those described in the embodiments, and any plating solution can be applied.
（比較例１）
質量％でNd：18.5％、Pr：5.2％、Dy：6.6％、Ｂ：0.9％、Co：2.0％、Al：0.10％、Ga：0.09％、Cu：0.10％、残部Feの主要成分組成であるR-T-B系磁石原料を粉砕し、成形・焼結・熱処理・加工することで65mm×30mm×5mmのR-T-B系磁石素材（以下、単に「磁石素材」という）とした。
(Comparative Example 1)
By mass% Nd: 18.5%, Pr: 5.2%, Dy: 6.6%, B: 0.9%, Co: 2.0%, Al: 0.10%, Ga: 0.09%, Cu: 0.10%, remaining Fe A RTB magnet material (hereinafter referred to simply as “magnet material”) of 65 mm × 30 mm × 5 mm was obtained by grinding, molding, sintering, heat treatment, and processing a certain RTB magnet material.
より密着性に優れためっき膜を得るためには、磁石素材表面の付着物（酸化膜、油脂等）を除去し、表面をあらす必要がある。ここでは、以下に示す前処理を行った。
硫酸系前処理液
[１]第一酸洗： 硝酸ナトリウム 17g/L ＋ 硫酸 9ml/L
室温、3min
[２]第二酸洗： 硝酸ナトリウム 17g/L ＋ 硫酸 16ml/L
室温、90s
[３]アルカリ超音波洗浄： 水酸化ナトリウム 50g/L
室温、3min
In order to obtain a plating film with better adhesion, it is necessary to remove the deposits (oxide film, fats and oils) on the surface of the magnet material and to reveal the surface. Here, the following pretreatment was performed.
Sulfuric acid pretreatment liquid
[1] First pickling: Sodium nitrate 17g / L + Sulfuric acid 9ml / L
Room temperature, 3min
[2] Secondary pickling: Sodium nitrate 17g / L + Sulfuric acid 16ml / L
Room temperature, 90s
[3] Alkaline ultrasonic cleaning: Sodium hydroxide 50g / L
Room temperature, 3min
[１]及び[２]の酸洗浄により、磁石素材表面の酸化膜を除去すると共に結晶粒界をエッチングしてめっき膜とのアンカー効果を持たせ、[３]のアルカリ超音波洗浄により表面のpHを中和すると共に[１][２]で発生したスマットを除去した。 The acid cleaning of [1] and [2] removes the oxide film on the surface of the magnet material and etches the crystal grain boundary to provide an anchor effect with the plating film. While neutralizing pH, the smut generated in [1] [2] was removed.
酸洗浄としては[１][２]以外にも硝酸系洗浄液等を用いることができるが、何れの場合にも前処理後に充分な水洗、乾燥を行い、水分がアルミニウムめっき液に混入しないよう注意しなければならない。 In addition to [1] and [2], nitric acid-based cleaning solutions can be used for acid cleaning, but in any case, perform sufficient water washing and drying after pretreatment so that moisture does not enter the aluminum plating solution. Must.
電気アルミニウムめっき液としては、ジメチルスルホンと塩化アルミニウムが５：１のモル比になるように調整しためっき液を使用した。めっき温度は１１０℃、電流密度は３A/dm2である。アルミニウムめっき膜厚40μｍとし、表面を酸化させずに塩水噴霧試験（35℃、５％NaCl水溶液噴霧）による耐食性評価を行った結果、被膜は２４時間で変色した。 As the electroaluminum plating solution, a plating solution adjusted to have a molar ratio of dimethylsulfone and aluminum chloride of 5: 1 was used. The plating temperature is 110 ° C. and the current density is 3 A / dm 2 . As a result of the corrosion resistance evaluation by a salt spray test (35 ° C., 5% NaCl aqueous solution spray) without oxidizing the surface with an aluminum plating film thickness of 40 μm, the coating changed color in 24 hours.
（実施例１）
比較例１と同様にして作製した磁石素材に比較例１と同様にして平均厚さ40μｍのアルミニウムめっき膜を形成し、更に100℃のトリエタノールアミン0.3vol％水溶液に３時間浸漬すること（熱水酸化）によって酸化膜を形成した。その断面写真を図１に示す。電気めっきであるため膜厚分布を生じているが、断面観察場所では磁石素地の上に厚さ30μｍのアルミニウムめっき膜が生成し、アルミニウムめっき膜は表面から深さ2μｍにわたって酸化膜に変化していた。この酸化膜はＸ線回折による分析をしたところα-Al2O3・H2Oからなるベーマイト層であることが確認された。図２(a)に示すように塩水噴霧試験1000時間後も錆の発生などの外観変化はなく、極めて良好な耐食性を示した。尚、図２(b)に示すように同様の磁石素材にNi/Cu/Ni被膜を形成したR-T-B系希土類磁石では、塩水噴霧試験48時間後に赤錆の発生が認められた。
Example 1
An aluminum plating film having an average thickness of 40 μm is formed on the magnet material produced in the same manner as in Comparative Example 1, and then immersed in a 0.3 vol% aqueous solution of triethanolamine at 100 ° C. for 3 hours (heat An oxide film was formed by hydroxylation. The cross-sectional photograph is shown in FIG. Although it is electroplating, a film thickness distribution occurs, but at the cross-sectional observation place, an aluminum plating film with a thickness of 30 μm is formed on the magnet substrate, and the aluminum plating film changes from the surface to an oxide film over a depth of 2 μm. It was. When this oxide film was analyzed by X-ray diffraction, it was confirmed that it was a boehmite layer made of α-Al 2 O 3 .H 2 O. As shown in FIG. 2 (a), there was no change in appearance such as rusting even after 1000 hours of the salt spray test, indicating extremely good corrosion resistance. As shown in FIG. 2B, in the RTB rare earth magnet in which a Ni / Cu / Ni film was formed on the same magnet material, red rust was observed after 48 hours of the salt spray test.
10mm×10mm×11mmの磁石素材に実施例１と同様にして被膜を形成したR-T-B系希土類磁石と同様の磁石素材にNi/Cu/Ni被膜を形成したR-T-B系希土類磁石を用いて塩水噴霧試験時間と保持力の関係を調べた。その結果を図３に示す。実施例１（Ａｌめっき）のR-T-B系希土類磁石は従来のNi/Cu/Niめっきと比較して耐食性に優れているため磁力の劣化が少なくなっている。 Salt spray test time using RTB rare earth magnet with Ni / Cu / Ni coating on the same magnet material as RTB rare earth magnet with 10mm × 10mm × 11mm magnet coating as in Example 1. And the relationship between the holding power. The result is shown in FIG. The R-T-B rare earth magnet of Example 1 (Al plating) is superior in corrosion resistance as compared with the conventional Ni / Cu / Ni plating, so that the magnetic force is less deteriorated.
本発明においてベーマイト層の厚さは0.2〜5μｍとすることが好ましい。0.2μｍ未満では酸化膜によるコーティングが不充分であるためピンホールからＡｌめっき膜が腐食するという不都合が生じる。5μｍを超えると処理時間が長くなり作業効率が低下するという不都合が生じる。熱水酸化ではアルミニウム膜厚以上に酸化させると磁石素材の酸化が進行して赤錆が発生し減磁率が大きくなってしまう。 In the present invention, the thickness of the boehmite layer is preferably 0.2 to 5 μm. If the thickness is less than 0.2 μm, the coating with the oxide film is insufficient, which causes a disadvantage that the Al plating film corrodes from the pinhole. If it exceeds 5 μm, the processing time becomes long and the work efficiency is lowered. In thermal hydroxylation, if the film is oxidized more than the aluminum film thickness, the oxidation of the magnet material proceeds to cause red rust and increase the demagnetization factor.
（実施例２）
比較例１と同様にして作製した磁石素材に比較例１と同様にして平均厚さ40μｍのアルミニウムめっき膜を作製し、硫酸系化成液中にて陽極酸化を行った。アルミニウムめっき膜は表面から深さ約10μｍにわたって酸化膜に変化していた。この酸化膜はＸ線回折による分析をしたところ非晶質アルミナからなるアルマイト層であることが確認された。塩水噴霧試験の結果、図４に示すように1000時間まで錆の発生は認められなかった。
(Example 2)
An aluminum plating film having an average thickness of 40 μm was produced on the magnet material produced in the same manner as in Comparative Example 1 in the same manner as in Comparative Example 1, and anodized in a sulfuric acid-based chemical liquid. The aluminum plating film was changed to an oxide film over a depth of about 10 μm from the surface. When this oxide film was analyzed by X-ray diffraction, it was confirmed that it was an alumite layer made of amorphous alumina. As a result of the salt spray test, no rust was observed up to 1000 hours as shown in FIG.
本発明においてアルマイト層の厚さは5〜10μｍとすることが好ましい。5μｍ未満では防食作用が不充分になるという不都合が生じる。10μｍを超えると防食作用は既に必要にして充分であり、かえってＡｌめっき膜の薄い部分で素地が溶解するという不都合が生じる。 In the present invention, the thickness of the alumite layer is preferably 5 to 10 μm. If it is less than 5 μm, there arises a disadvantage that the anticorrosive action becomes insufficient. If it exceeds 10 μm, the anticorrosion action is already necessary and sufficient, and the disadvantage is that the substrate is dissolved in the thin part of the Al plating film.
（比較例２）
比較例１と同様にして作製した磁石素材に比較例１と同様にして平均厚さ5μｍのアルミニウムめっき膜を作製し、硫酸系化成液を用いて陽極酸化を行った。図５に示すように試料中央のめっき膜が薄い部分では、磁石素材を被覆するアルミニウムめっき膜が残っていないため磁石素材の腐食が認められる。陽極酸化ではアルミニウム膜厚以上に酸化させると素地が溶解し減磁率が大きくなってしまう。熱水酸化の場合は素地の酸化が進行して赤錆が発生した。
(Comparative Example 2)
An aluminum plating film having an average thickness of 5 μm was produced on the magnet material produced in the same manner as in Comparative Example 1 in the same manner as in Comparative Example 1, and anodization was performed using a sulfuric acid-based chemical conversion solution. As shown in FIG. 5, in the portion where the plating film at the center of the sample is thin, corrosion of the magnet material is recognized because the aluminum plating film covering the magnet material does not remain. In anodic oxidation, if the film is oxidized to a thickness greater than the aluminum film thickness, the substrate melts and the demagnetization factor increases. In the case of thermal hydroxylation, oxidation of the substrate progressed and red rust was generated.
Claims (6)
An aluminum coating is formed on the surface of an RTB rare earth magnet (R is at least one rare earth element including Y and T is Fe or Fe and Co) by electroaluminum plating, and a part of the aluminum coating is oxidized. A method for producing a highly corrosion-resistant RTB rare earth magnet characterized by comprising an oxidation-resistant layer.
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| JP2012017484A (en) * | 2010-07-06 | 2012-01-26 | Kobe Steel Ltd | Steel for bolt, bolt, and method for production of the bolt |
| WO2014158767A1 (en) * | 2013-03-14 | 2014-10-02 | Applied Materials, Inc. | High purity aluminum top coat on substrate |
| EP3018232A1 (en) * | 2014-11-04 | 2016-05-11 | Yantai Shougang Magnetic Materials Inc. | Nd-fe-b magnet with aluminum hard film coating and preparation method thereof |
| US9624593B2 (en) | 2013-08-29 | 2017-04-18 | Applied Materials, Inc. | Anodization architecture for electro-plate adhesion |
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| JP2012017484A (en) * | 2010-07-06 | 2012-01-26 | Kobe Steel Ltd | Steel for bolt, bolt, and method for production of the bolt |
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| US9850591B2 (en) | 2013-03-14 | 2017-12-26 | Applied Materials, Inc. | High purity aluminum top coat on substrate |
| WO2014158767A1 (en) * | 2013-03-14 | 2014-10-02 | Applied Materials, Inc. | High purity aluminum top coat on substrate |
| US9624593B2 (en) | 2013-08-29 | 2017-04-18 | Applied Materials, Inc. | Anodization architecture for electro-plate adhesion |
| US9663870B2 (en) | 2013-11-13 | 2017-05-30 | Applied Materials, Inc. | High purity metallic top coat for semiconductor manufacturing components |
| US9879348B2 (en) | 2013-11-13 | 2018-01-30 | Applied Materials, Inc. | High purity metallic top coat for semiconductor manufacturing components |
| US10260160B2 (en) | 2013-11-13 | 2019-04-16 | Applied Materials, Inc. | High purity metallic top coat for semiconductor manufacturing components |
| EP3018232A1 (en) * | 2014-11-04 | 2016-05-11 | Yantai Shougang Magnetic Materials Inc. | Nd-fe-b magnet with aluminum hard film coating and preparation method thereof |
| JP2016089270A (en) * | 2014-11-04 | 2016-05-23 | 煙台首鋼磁性材料株式有限公司 | Method of forming hard aluminum coating on the surface of neodymium iron boron magnet, and neodymium iron boron magnet having the hard aluminum coating |
| WO2022198539A1 (en) * | 2021-03-25 | 2022-09-29 | 江西艾特磁材有限公司 | Method for preparing ball milling-modified sol-gel coated magnetic powder core |
| CN113394017A (en) * | 2021-06-10 | 2021-09-14 | 北京工业大学 | Method for sintering neodymium iron boron by electroplating electrophoresis in cooperation with deposition diffusion |
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