JP2005344189A - Method for improving wettability of nickel plating film formed on surface of article - Google Patents
Method for improving wettability of nickel plating film formed on surface of article Download PDFInfo
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- JP2005344189A JP2005344189A JP2004167753A JP2004167753A JP2005344189A JP 2005344189 A JP2005344189 A JP 2005344189A JP 2004167753 A JP2004167753 A JP 2004167753A JP 2004167753 A JP2004167753 A JP 2004167753A JP 2005344189 A JP2005344189 A JP 2005344189A
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- 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
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- 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
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
- C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
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- 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
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
- C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
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- 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
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
- C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
- C23C28/3455—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer
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- Ceramic Engineering (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
- Chemical Treatment Of Metals (AREA)
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Abstract
Description
本発明は、希土類系永久磁石をはじめとする各種の物品の表面に形成したニッケルめっき被膜の濡れ性を改善する方法に関する。 The present invention relates to a method for improving the wettability of a nickel plating film formed on the surface of various articles including a rare earth permanent magnet.
Ｎｄ−Ｆｅ−Ｂ系永久磁石に代表されるＲ−Ｆｅ−Ｂ系永久磁石やＳｍ−Ｆｅ−Ｎ系永久磁石に代表されるＲ−Ｆｅ−Ｎ系永久磁石などの希土類系永久磁石は、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、特にＲ−Ｆｅ−Ｂ系永久磁石は今日様々な分野で使用されている。しかしながら、希土類系永久磁石は反応性の高い希土類元素：Ｒ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恐れがある。上記の点に鑑み、希土類系永久磁石の表面に優れた耐食性を有する被膜としてニッケルめっき被膜を形成する方法が広く採用されている。しかしながら、表面にニッケルめっき被膜を有する希土類系永久磁石を部品（モータや電子部品など）に組み込む際、ニッケルめっき被膜と部品との間には、接着剤を介した強い接着性が要求されるにもかかわらず、ニッケルめっき被膜はアルミニウム蒸着被膜などと比較して、強い接着性を獲得するための第一条件とも言える濡れ性に劣ることから、接着剥がれなどの問題が発生することがある。 Rare earth permanent magnets such as R—Fe—B permanent magnets represented by Nd—Fe—B permanent magnets and R—Fe—N permanent magnets represented by Sm—Fe—N permanent magnets are In particular, R-Fe-B based permanent magnets are used in various fields today because they use abundant and inexpensive materials and have high magnetic properties. However, since rare earth permanent magnets contain a highly reactive rare earth element: R, they are easily oxidatively corroded in the atmosphere. When used without any surface treatment, a slight amount of acid, alkali, moisture, etc. Corrosion proceeds from the surface due to the presence of rust, and rust is generated, resulting in deterioration and variation in magnet characteristics. Furthermore, when a magnet in which rust is generated is incorporated in an apparatus such as a magnetic circuit, the rust may be scattered to contaminate peripheral components. In view of the above points, a method of forming a nickel plating film as a film having excellent corrosion resistance on the surface of a rare earth permanent magnet has been widely adopted. However, when a rare earth permanent magnet having a nickel plating film on the surface is incorporated into a component (such as a motor or electronic component), strong adhesion via an adhesive is required between the nickel plating film and the component. Nevertheless, since the nickel plating film is inferior in wettability, which can be said to be the first condition for obtaining strong adhesiveness, compared with an aluminum vapor-deposited film, problems such as adhesion peeling may occur.
上記のような問題を解決するため方法としては、ニッケルめっき被膜の濡れ性を改善するために、ニッケルめっき被膜の表面に化成処理被膜を形成する方法が考えられる。しかしながら、ニッケルは、亜鉛や鉄などと比較して貴な金属であるので、単にニッケルが関与する酸化還元反応を利用した化成処理では、その表面に化成処理被膜を形成することは非常に困難である。そこで、このような事情を考慮した上で、ニッケルめっき被膜の表面に化成処理被膜を形成する方法として、特許文献１においては、ニッケルめっき被膜の表面にクロム酸塩被膜を形成する方法が提案されており、特許文献２においては、ニッケルめっき被膜の表面にリン酸亜鉛被膜を形成する方法が提案されている。
上記のいずれの特許文献で提案されている方法も、ニッケルめっき被膜の濡れ性の改善を図ることができる点において優れたものである。しかしながら、特許文献１で提案されている方法では、環境や人体への影響を考慮すれば使用を控えたい６価クロムを含有する処理液を用いる必要があり、特許文献２で提案されている方法では、ニッケルめっき被膜の表面にリン酸亜鉛被膜を形成するためには、ニッケルめっき被膜の表面でリン酸が酸化還元反応するだけでは不十分であることから、反応性が高く安定性に劣る処理液を用いてニッケルめっき被膜の表面をエッチングする必要がある。従って、どちらの方法も、実用面においては必ずしも満足できるに足るものではないことから、ニッケルめっき被膜の濡れ性を改善するための新しい方法が求められている。
そこで本発明は、希土類系永久磁石をはじめとする各種の物品の表面に形成したニッケルめっき被膜の濡れ性を、環境に優しく簡便に改善する方法を提供することを目的とする。
The methods proposed in any of the above patent documents are excellent in that the wettability of the nickel plating film can be improved. However, in the method proposed in Patent Document 1, it is necessary to use a treatment liquid containing hexavalent chromium that should not be used in consideration of the influence on the environment and the human body. The method proposed in Patent Document 2 Then, in order to form a zinc phosphate coating on the surface of the nickel plating coating, it is not sufficient that phosphoric acid undergoes a redox reaction on the surface of the nickel plating coating. It is necessary to etch the surface of the nickel plating film using a liquid. Therefore, both methods are not always satisfactory in practical use, and therefore a new method for improving the wettability of the nickel plating film is required.
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily and easily improving the wettability of a nickel plating film formed on the surface of various articles including rare earth permanent magnets.
本発明者は上記の点に鑑み鋭意検討を行った結果、電解還元法によりニッケルめっき被膜の表面にモリブデン酸塩被膜を電着して形成することで、ニッケルめっき被膜の濡れ性を、環境に優しく簡便に改善することができることを知見した。 As a result of intensive studies in view of the above points, the present inventor has formed an electroreduction method by electrodepositing a molybdate film on the surface of the nickel plating film, so that the wettability of the nickel plating film can It was found that it can be improved gently and easily.
上記の知見に基づいてなされた本発明の物品の表面に形成したニッケルめっき被膜の濡れ性を改善する方法は、請求項１記載の通り、ニッケルめっき被膜の表面にモリブデン酸塩被膜を形成することを特徴とする。
また、請求項２記載の方法は、請求項１記載の方法において、モリブデン酸塩被膜がモリブデン酸ナトリウム被膜またはモリブデン酸カリウム被膜であることを特徴とする。
また、請求項３記載の方法は、請求項１または２記載の方法において、ニッケルめっき被膜の表面へのモリブデン酸塩被膜の付着量が膜厚として０．００５μｍ〜１μｍであることを特徴とする。
また、請求項４記載の方法は、請求項１乃至３のいずれかに記載の方法において、ニッケルめっき被膜を表面に有する物品を、モリブデン酸錯体を含有する処理液に浸漬し、電解還元法によりニッケルめっき被膜の表面にモリブデン酸塩被膜を電着して形成することを特徴とする。
また、請求項５記載の方法は、請求項４記載の方法において、モリブデン酸錯体を含有する処理液を、モリブデン酸塩と、クエン酸塩，酢酸塩，コハク酸塩，マロン酸塩，酒石酸塩，グルコン酸塩から選ばれる少なくとも１種類の錯化剤を用いて調製することを特徴とする。
また、請求項６記載の方法は、請求項５記載の方法において、モリブデン酸錯体を含有する処理液を、モリブデン酸塩としてモリブデン酸ナトリウムまたはモリブデン酸カリウムと、錯化剤としてクエン酸ナトリウムまたはクエン酸カリウムを用いて調製することを特徴とする。
また、請求項７記載の方法は、請求項４乃至６のいずれかに記載の方法において、モリブデン酸錯体を含有する処理液が硫酸アルカリ金属塩を更に含有してなることを特徴とする。
また、請求項８記載の方法は、請求項１乃至７のいずれかに記載の方法において、物品が希土類系永久磁石であることを特徴とする。
また、本発明のニッケルめっき被膜の濡れ性が改善された物品は、請求項９記載の通り、ニッケルめっき被膜を介してモリブデン酸塩被膜を表面に有してなることを特徴とする。
また、本発明のニッケルめっき被膜の濡れ性が改善された物品の製造方法は、請求項１０記載の通り、ニッケルめっき被膜を表面に有する物品を、モリブデン酸錯体を含有する処理液に浸漬し、電解還元法によりニッケルめっき被膜の表面にモリブデン酸塩被膜を電着して形成することを特徴とする。
The method for improving the wettability of the nickel plating film formed on the surface of the article of the present invention made based on the above knowledge forms a molybdate film on the surface of the nickel plating film as claimed in claim 1. It is characterized by.
The method according to claim 2 is the method according to claim 1, wherein the molybdate film is a sodium molybdate film or a potassium molybdate film.
The method according to claim 3 is characterized in that, in the method according to claim 1 or 2, the adhesion amount of the molybdate film to the surface of the nickel plating film is 0.005 μm to 1 μm as a film thickness. .
The method according to claim 4 is the method according to any one of claims 1 to 3, wherein an article having a nickel plating film on the surface is dipped in a treatment solution containing a molybdate complex, and the electrolytic reduction method is used. It is characterized in that a molybdate film is formed by electrodeposition on the surface of the nickel plating film.
The method according to claim 5 is the method according to claim 4, wherein the treatment liquid containing the molybdate complex is treated with molybdate, citrate, acetate, succinate, malonate, tartrate. , Prepared using at least one complexing agent selected from gluconates.
The method according to claim 6 is the method according to claim 5, wherein the treatment liquid containing the molybdate complex is treated with sodium molybdate or potassium molybdate as molybdate and sodium citrate or citric acid as complexing agent. It is characterized by being prepared using potassium acid.
The method according to claim 7 is the method according to any one of claims 4 to 6, wherein the treatment liquid containing the molybdate complex further contains an alkali metal sulfate salt.
The method according to claim 8 is the method according to any one of claims 1 to 7, wherein the article is a rare earth-based permanent magnet.
Moreover, the article in which the wettability of the nickel plating film of the present invention is improved is characterized by having a molybdate film on the surface through the nickel plating film as described in claim 9.
The method for producing an article with improved wettability of the nickel plating film according to the present invention includes immersing an article having a nickel plating film on the surface thereof in a treatment liquid containing a molybdate complex as described in claim 10, It is characterized in that a molybdate film is electrodeposited on the surface of the nickel plating film by electrolytic reduction.
本発明によれば、希土類系永久磁石をはじめとする各種の物品の表面に形成したニッケルめっき被膜の濡れ性を、環境に優しく簡便に改善する方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the method of improving the wettability of the nickel plating film formed in the surface of various articles | goods including rare earth-type permanent magnets easily to an environment can be provided.
本発明が適用される物品としては、希土類系永久磁石を具体例として挙げることができるが、その表面に形成したニッケルめっき被膜に優れた濡れ性が要求される物品であれば、どのようなものであってもよい。 As an article to which the present invention is applied, a rare earth permanent magnet can be given as a specific example, but any article that requires excellent wettability to a nickel plating film formed on its surface can be used. It may be.
物品の表面に形成されるニッケルめっき被膜は、自体公知の電解ニッケルめっきを含め、どのような方法で形成されたものでもよい。また、ニッケルめっき被膜は、物品の表面に直接的に形成されたものでもよいし、他の被膜を介して間接的に形成されたものでもよい。 The nickel plating film formed on the surface of the article may be formed by any method including electrolytic nickel plating known per se. Further, the nickel plating film may be formed directly on the surface of the article, or may be formed indirectly through another film.
ニッケルめっき被膜の表面に形成するモリブデン酸塩被膜としては、モリブデン酸リチウム被膜，モリブデン酸ナトリウム被膜，モリブデン酸カリウム被膜などのモリブデン酸アルカリ金属被膜が挙げられる。ニッケルめっき被膜の表面へのモリブデン酸塩被膜の形成は、例えば、ニッケルめっき被膜を表面に有する物品を、モリブデン酸錯体を含有する処理液に浸漬し、電解還元法によりニッケルめっき被膜の表面にモリブデン酸塩被膜を電着することで行うことができる。モリブデン酸錯体を含有する処理液は、モリブデン酸アルカリ金属塩などのモリブデン酸塩と、錯化剤を用いて調製することができる。錯化剤としては、クエン酸塩，酢酸塩，コハク酸塩，マロン酸塩，酒石酸塩，グルコン酸塩（アルカリ金属塩など）などが挙げられる。モリブデン酸ナトリウム被膜やモリブデン酸カリウム被膜は、ニッケルめっき被膜の濡れ性の改善効果にとりわけ優れるので、モリブデン酸錯体を含有する処理液は、モリブデン酸塩としてモリブデン酸ナトリウムまたはモリブデン酸カリウムと、錯化剤としてクエン酸ナトリウムまたはクエン酸カリウムを用いて調製することが望ましい。前述の通り、ニッケルは、亜鉛や鉄などと比較して貴な金属であるので、単にニッケルが関与する酸化還元反応を利用した化成処理では、その表面に化成処理被膜を形成することは非常に困難であり、特許文献１や特許文献２に記載されているような特殊な方法を採らなければならないが、電解還元法によれば、モリブデン酸塩と錯化剤から生成するモリブデン酸錯体が、電解金属めっきのように電解還元反応して錯化剤イオンを後方放電させることで、ニッケルめっき被膜の表面へのモリブデン酸塩の析出が効果的に起こり、その結果として、モリブデン酸塩被膜を優れた密着性をもってニッケルめっき被膜の表面に形成することができるものと考えられる。 Examples of the molybdate film formed on the surface of the nickel plating film include an alkali metal molybdate film such as a lithium molybdate film, a sodium molybdate film, and a potassium molybdate film. Formation of a molybdate film on the surface of the nickel plating film is performed, for example, by immersing an article having a nickel plating film on the surface in a treatment solution containing a molybdate complex, and then applying molybdenum to the surface of the nickel plating film by an electrolytic reduction method. This can be done by electrodeposition of an acid salt film. The treatment liquid containing the molybdate complex can be prepared using a molybdate such as an alkali metal molybdate and a complexing agent. Examples of the complexing agent include citrate, acetate, succinate, malonate, tartrate, gluconate (alkali metal salt, etc.) and the like. Sodium molybdate coating and potassium molybdate coating are particularly excellent in improving the wettability of nickel plating coating, so the treatment solution containing molybdate complex is complexed with sodium molybdate or potassium molybdate as molybdate. It is desirable to prepare using sodium citrate or potassium citrate as the agent. As described above, since nickel is a noble metal compared to zinc, iron, etc., it is very difficult to form a chemical conversion coating on the surface by chemical conversion treatment using a redox reaction involving nickel. It is difficult and special methods such as those described in Patent Document 1 and Patent Document 2 must be adopted. According to the electrolytic reduction method, the molybdate complex produced from the molybdate and the complexing agent is Electrolytic reduction reaction as in electrolytic metal plating causes the complexing agent ions to discharge backward, thereby effectively depositing molybdate on the surface of the nickel plating film. As a result, the molybdate film is excellent. It is considered that it can be formed on the surface of the nickel plating film with high adhesion.
モリブデン酸錯体を含有する処理液は、水にモリブデン酸塩と錯化剤を溶解することで調製することができる。モリブデン酸塩は、処理液中の濃度が０．０１ｍｏｌ／Ｌ〜３．０ｍｏｌ／Ｌとなるように溶解することが望ましい。処理液中の濃度が０．０１ｍｏｌ／Ｌを下回ると、電流効率が著しく低下することで処理中における水素ガスの発生が顕著となって、ニッケルめっき被膜の表面に焦げなどを発生させてしまう恐れがある。一方、処理液中の濃度が３．０ｍｏｌ／Ｌを上回っても電流効率に変化はなく、生産性の向上を図ることができずにコスト上昇を招くだけといったことになる恐れがある。錯化剤は、処理液中の濃度が０．０１５ｍｏｌ／Ｌ〜５．０ｍｏｌ／Ｌとなるように溶解することが望ましい。処理液中の濃度が０．０１５ｍｏｌ／Ｌを下回ると、モリブデン酸イオンに対して十分に錯体形成することができないことで、処理液の安定性が低下し、ニッケルめっき被膜の表面にモリブデン酸塩被膜を安定に、かつ、優れた密着性でもって形成することができない恐れがある。一方、処理液中の濃度が５．０ｍｏｌ／Ｌを上回ると、電流効率が低下するといった問題が生じる恐れがある。 A treatment liquid containing a molybdate complex can be prepared by dissolving molybdate and a complexing agent in water. The molybdate is desirably dissolved so that the concentration in the treatment liquid is 0.01 mol / L to 3.0 mol / L. When the concentration in the treatment liquid is less than 0.01 mol / L, current efficiency is remarkably lowered, so that generation of hydrogen gas during the treatment becomes remarkable, and the surface of the nickel plating film may be burnt. There is. On the other hand, even if the concentration in the treatment liquid exceeds 3.0 mol / L, there is no change in current efficiency, and it may not be possible to improve productivity and only increase costs. The complexing agent is desirably dissolved so that the concentration in the treatment liquid is 0.015 mol / L to 5.0 mol / L. If the concentration in the treatment liquid is less than 0.015 mol / L, the complex cannot be sufficiently formed with molybdate ions, so that the stability of the treatment liquid is lowered, and the surface of the nickel plating film is molybdate. There is a possibility that the film cannot be formed stably and with excellent adhesion. On the other hand, when the concentration in the treatment liquid exceeds 5.0 mol / L, there is a possibility that a problem that current efficiency is lowered may occur.
処理液は、必要であれば硫酸などを用いてｐＨを２．０〜９．０に調製することが望ましい。ｐＨが２．０を下回ると、ニッケルめっき被膜の表面へのモリブデン酸塩被膜の電着速度が速すぎてその膜厚制御が困難になり、表面ムラなどを発生させてしまう恐れがあることに加え、物品が希土類系永久磁石の場合には、磁石の磁気特性が酸化腐食により劣化する恐れがある。一方、ｐＨが９．０を上回ると、モリブデン酸錯体が生成せずに、電解還元反応が起こらない恐れがある。 It is desirable that the treatment liquid is adjusted to a pH of 2.0 to 9.0 using sulfuric acid or the like if necessary. If the pH is less than 2.0, the electrodeposition rate of the molybdate film on the surface of the nickel plating film is too high, making it difficult to control the film thickness and possibly causing surface unevenness. In addition, when the article is a rare earth permanent magnet, the magnetic properties of the magnet may deteriorate due to oxidative corrosion. On the other hand, if the pH exceeds 9.0, the molybdate complex is not formed, and there is a possibility that the electrolytic reduction reaction does not occur.
処理液は、液温を２０℃〜７０℃にして用いることが望ましい。液温が２０℃を下回ると、電解還元反応が効率よく起こらない恐れがある。一方、液温が７０℃を上回ると、ニッケルめっき被膜の表面へのモリブデン酸塩被膜の電着速度が速すぎてその膜厚制御が困難になり、表面ムラなどを発生させてしまう恐れがあることに加え、処理液の管理や連続操業が困難になる恐れがある。 The treatment liquid is preferably used at a liquid temperature of 20 ° C to 70 ° C. When the liquid temperature is lower than 20 ° C, the electrolytic reduction reaction may not occur efficiently. On the other hand, if the liquid temperature is higher than 70 ° C., the electrodeposition rate of the molybdate film on the surface of the nickel plating film is too high, making it difficult to control the film thickness, which may cause surface unevenness. In addition, management of the processing liquid and continuous operation may be difficult.
なお、処理液には、導電性を向上させることを目的として、硫酸ナトリウムや硫酸カリウムなどの硫酸アルカリ金属塩を、処理液中の濃度が０．０５ｍｏｌ／Ｌ〜２．０ｍｏｌ／Ｌとなるように溶解することが望ましく、０．１ｍｏｌ／Ｌ〜１．０ｍｏｌ／Ｌとなるように溶解することがより望ましい。処理液中の濃度が０．０５ｍｏｌ／Ｌを下回ると、導電性の向上を図ることができない恐れがある。一方、処理液中の濃度が２．０ｍｏｌ／Ｌを上回っても導電性に変化はなく、生産性の向上を図ることができずにコスト上昇を招くだけといったことになる恐れがある。 In addition, for the purpose of improving conductivity, the treatment liquid is added with an alkali metal sulfate such as sodium sulfate or potassium sulfate so that the concentration in the treatment liquid is 0.05 mol / L to 2.0 mol / L. It is desirable to dissolve in 0.1 mol / L to 1.0 mol / L. If the concentration in the treatment liquid is less than 0.05 mol / L, the conductivity may not be improved. On the other hand, even if the concentration in the treatment liquid exceeds 2.0 mol / L, there is no change in conductivity, and there is a risk that productivity cannot be improved and cost is increased.
電解還元法によるニッケルめっき被膜の表面へのモリブデン酸塩被膜の電着形成は、電流密度を０．１ｍＡ／ｃｍ2〜３０ｍＡ／ｃｍ2にして行うことが望ましい。電流密度が０．１ｍＡ／ｃｍ2を下回ると、電解還元反応が効率よく起こらない恐れがある。一方、電流密度が３０ｍＡ／ｃｍ2を上回ると、処理中における水素ガスの発生が顕著となって、ニッケルめっき被膜の表面に焦げなどを発生させてしまう恐れがある。なお、処理時間は、ニッケルめっき被膜の表面へのモリブデン酸塩被膜の付着量にもよるが、概ね、６０秒〜６００秒である。 Electrodeposition formation of molybdate coating the surface of the nickel plating film by electrolytic reduction method is preferably performed by a current density of 0.1mA / cm 2 ~30mA / cm 2 . When the current density is less than 0.1 mA / cm 2 , the electrolytic reduction reaction may not occur efficiently. On the other hand, when the current density exceeds 30 mA / cm 2 , the generation of hydrogen gas during the treatment becomes significant, and there is a possibility that the surface of the nickel plating film may be burned. The treatment time is generally 60 seconds to 600 seconds, although it depends on the amount of molybdate film attached to the surface of the nickel plating film.
ニッケルめっき被膜の表面へのモリブデン酸塩被膜の付着量は、膜厚として０．００５μｍ〜１μｍであることが望ましい。付着量が膜厚として０．００５μｍを下回ると、ニッケルめっき被膜の濡れ性の改善効果が得られない恐れがある。一方、付着量が膜厚として１μｍを上回ると、モリブデン酸塩被膜にクラックが生じてその機能を果たさない恐れがある。 The adhesion amount of the molybdate film to the surface of the nickel plating film is preferably 0.005 μm to 1 μm as the film thickness. When the adhesion amount is less than 0.005 μm as the film thickness, there is a possibility that the effect of improving the wettability of the nickel plating film cannot be obtained. On the other hand, if the adhesion amount exceeds 1 μm as a film thickness, the molybdate film may crack and may not perform its function.
以下、本発明を実施例と比較例によってさらに詳細に説明するが、本発明はこれに限定して解釈されるものではない。なお、以下の実施例と比較例は、例えば、米国特許４７７０７２３号公報や米国特許４７９２３６８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１４Ｎｄ−７９Ｆｅ−６Ｂ−１Ｃｏ組成（ａｔ％）の縦４０ｍｍ×横２０ｍｍ×高さ２ｍｍ寸法の板状焼結磁石（以下、磁石体試験片と称する）を用いて行った。 EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is limited to this and is not interpreted. In the following examples and comparative examples, for example, as described in US Pat. No. 4,770,723 and US Pat. No. 4,792,368, a known cast ingot is pulverized, and after pulverization, molding, sintering, and heat treatment are performed. A plate-like sintered magnet having a composition of 14Nd-79Fe-6B-1Co (at%) obtained by performing surface processing and having dimensions of 40 mm in length, 20 mm in width, and 2 mm in height (hereinafter referred to as a magnet specimen). Used.
Ａ：ニッケルめっき被膜を介してモリブデン酸塩被膜を表面に有する磁石体試験片の製造
（工程１）
磁石体試験片を硝酸ナトリウム０．２ｍｏｌ／Ｌと硫酸１．５ｖｏｌ％を含んだ液温３０℃の酸洗液に４分間浸漬し、その表面を酸洗した後、水洗し、以下の条件で磁石体試験片の表面に膜厚３μｍ（ｎ＝１０の平均値）の第１ニッケルめっき被膜を形成した。
A: Manufacture of a magnet specimen having a molybdate coating on the surface via a nickel plating coating (step 1)
The magnet body test piece was immersed for 4 minutes in a pickling solution containing sodium nitrate 0.2 mol / L and sulfuric acid 1.5 vol% at a liquid temperature of 30 ° C., and the surface was pickled, then washed with water, under the following conditions: A first nickel plating film having a film thickness of 3 μm (average value of n = 10) was formed on the surface of the magnet body test piece.
液組成 硫酸ニッケル・６水和物 １３０ｇ／Ｌ
クエン酸二アンモニウム ５０ｇ／Ｌ
ホウ酸 １５ｇ／Ｌ
塩化アンモニウム １５ｇ／Ｌ
サッカリン ８ｇ／Ｌ
液温 ５０℃
ｐＨ ６．５（アンモニア水で調整）
電流密度 ０．２Ａ／ｄｍ2
処理時間 ２０分
Liquid composition Nickel sulfate hexahydrate 130g / L
Diammonium citrate 50g / L
Boric acid 15g / L
Ammonium chloride 15g / L
Saccharin 8g / L
Liquid temperature 50 ℃
pH 6.5 (adjusted with ammonia water)
Current density 0.2A / dm 2
Processing time 20 minutes
（工程２）
次に、以下の条件で第１ニッケルめっき被膜の表面に膜厚１０μｍ（ｎ＝１０の平均値）の第２ニッケルめっき被膜を形成した後、水洗した。
(Process 2)
Next, a second nickel plating film having a film thickness of 10 μm (n = 10 average value) was formed on the surface of the first nickel plating film under the following conditions, and then washed with water.
液組成 硫酸ニッケル・６水和物 ３００ｇ／Ｌ
塩化ニッケル・６水和物 ４５ｇ／Ｌ
ホウ酸 ５０ｇ／Ｌ
２−ブチン−１，４−ジオール ０．２ｇ／Ｌ
ラウリル硫酸ナトリウム １ｇ／Ｌ
液温 ５０℃
ｐＨ ４．２（塩基性炭酸ニッケルで調整）
電流密度 ０．２Ａ／ｄｍ2
処理時間 １４０分
Liquid composition Nickel sulfate hexahydrate 300g / L
Nickel chloride hexahydrate 45g / L
Boric acid 50g / L
2-Butyne-1,4-diol 0.2g / L
Sodium lauryl sulfate 1g / L
Liquid temperature 50 ℃
pH 4.2 (adjusted with basic nickel carbonate)
Current density 0.2A / dm 2
Processing time 140 minutes
（工程３）
次に、工程１と工程２を行うことで得た、表面に積層ニッケル被膜を有する磁石体試験片を再度水洗し、続いて、以下の条件で電解還元法により第２ニッケルめっき被膜の表面にモリブデン酸ナトリウム被膜を電着して形成した後、水洗し、エアワイピングし、７０℃で１０分間乾燥することで、積層ニッケルめっき被膜を介してモリブデン酸ナトリウム被膜を表面に有する磁石体試験片（以下、サンプルと称する）を得た。なお、乾燥処理の前後で外観の変化は認められなかった。
(Process 3)
Next, the magnetic body test piece having the laminated nickel film on the surface obtained by carrying out Step 1 and Step 2 is washed again with water, and subsequently, the surface of the second nickel plating film is electrolytically reduced under the following conditions. After forming the sodium molybdate film by electrodeposition, it was washed with water, air-wiped, and dried at 70 ° C. for 10 minutes, so that a magnet test piece having a sodium molybdate film on the surface through the laminated nickel plating film ( Hereinafter referred to as a sample). In addition, the change of the external appearance was not recognized before and after the drying process.
液組成 モリブデン酸ナトリウム・２水和物 ０．１ｍｏｌ／Ｌ
クエン酸三ナトリウム・２水和物 ０．１ｍｏｌ／Ｌ
硫酸ナトリウム ０．２ｍｏｌ／Ｌ
液温 ４０℃
ｐＨ ５．０（硫酸で調整）
電流密度 表１に記載
処理時間 表１に記載
Liquid composition Sodium molybdate dihydrate 0.1 mol / L
Trisodium citrate dihydrate 0.1 mol / L
Sodium sulfate 0.2 mol / L
Liquid temperature 40 ℃
pH 5.0 (adjusted with sulfuric acid)
Current density Table 1 Processing time Table 1
Ｂ：ニッケルめっき被膜の濡れ性の評価
サンプルに対し、６０℃×９０％ＲＨの耐湿試験を行い、試験開始前と、開始後２０分，１時間，４時間における濡れ性の評価を、サンプルの表面にＪＩＳ Ｋ ６７６８の濡れ張力試験液（４５ｄｙｎｅ／ｃｍ，４０ｄｙｎｅ／ｃｍ，３５ｄｙｎｅ／ｃｍ）をガラス棒につけて滴下することで行った。結果を表１に示す（実施例１と実施例２）。また、表面に積層ニッケル被膜を有する磁石体試験片に対し、同様の濡れ性の評価を行った結果を比較例として表１に示す。
B: Evaluation of the wettability of the nickel plating film The sample was subjected to a moisture resistance test at 60 ° C. × 90% RH, and the wettability was evaluated before starting the test and at 20 minutes, 1 hour, and 4 hours after the test. A JIS K 6768 wetting tension test solution (45 dyne / cm, 40 dyne / cm, 35 dyne / cm) was placed on a glass rod and dropped onto the surface. The results are shown in Table 1 (Example 1 and Example 2). Table 1 shows the results of a similar wettability evaluation performed on a magnet specimen having a laminated nickel coating on the surface as a comparative example.
表１から明らかなように、ニッケルめっき被膜の表面にモリブデン酸ナトリウム被膜を形成することで、その濡れ性を改善することができることがわかった。 As is apparent from Table 1, it was found that the wettability can be improved by forming a sodium molybdate coating on the surface of the nickel plating coating.
本発明は、希土類系永久磁石をはじめとする各種の物品の表面に形成したニッケルめっき被膜の濡れ性を、環境に優しく簡便に改善する方法を提供することができる点において産業上の利用可能性を有する。 INDUSTRIAL APPLICABILITY The present invention is industrially applicable in that it can provide a method for improving the wettability of a nickel plating film formed on the surface of various articles including rare earth permanent magnets in an environmentally friendly manner. Have
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| JPH04144101A (en) * | 1990-10-04 | 1992-05-18 | Hitachi Metals Ltd | R-tm-b permanent magnet, wherein corrosion resistance is improved, and its manufacture |
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| JP2003535224A (en) * | 2000-06-08 | 2003-11-25 | マクダーミッド インコーポレーテッド | Method for improving the adhesion of polymeric materials to metal surfaces |
| JP2002198241A (en) * | 2000-08-11 | 2002-07-12 | Sumitomo Special Metals Co Ltd | Rare earth permanent magnet having corrosion resistant film, and its manufacturing method |
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