JPH07135121A - Method for surface treatment of permanent magnet - Google Patents
Method for surface treatment of permanent magnetInfo
- Publication number
- JPH07135121A JPH07135121A JP26621093A JP26621093A JPH07135121A JP H07135121 A JPH07135121 A JP H07135121A JP 26621093 A JP26621093 A JP 26621093A JP 26621093 A JP26621093 A JP 26621093A JP H07135121 A JPH07135121 A JP H07135121A
- Authority
- JP
- Japan
- Prior art keywords
- plating
- film
- tin
- nickel
- plating film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/026—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets protecting methods against environmental influences, e.g. oxygen, by surface treatment
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Electroplating Methods And Accessories (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、希土類系永久磁石の表
面に保護皮膜を形成する表面処理方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for forming a protective film on the surface of a rare earth permanent magnet.
【０００２】[0002]
【従来の技術】希土類系永久磁石は、磁気特性に優れて
いるところから、各種電子、電気機器の磁気回路に多用
されるようになった。なかでもＮｄやＰｒを主とする軽
希土類を用いた鉄−硼素−希土類系永久磁石は、高いエ
ネルギー積を有する優れた磁石であり、その軽希土類元
素が資源的にも豊富なところから、利用分野が広がるも
のと期待される。また、さらなる磁気特性向上のための
研究開発も盛んに行われており、例えば、この種希土類
系磁石合金の組成の異なるものの粉体を混合して焼結す
ることにより、エネルギー積、保磁力および残留磁束密
度のバランスのとれた永久磁石を得る方法などが提案さ
れている。2. Description of the Related Art Rare earth permanent magnets have been widely used in magnetic circuits of various electronic and electric devices because of their excellent magnetic properties. Among them, iron-boron-rare earth permanent magnets using light rare earths mainly containing Nd and Pr are excellent magnets having a high energy product, and since the light rare earth elements are abundant in resources, they are used. It is expected that the fields will expand. Further, research and development for further improving magnetic properties are also actively carried out. For example, by mixing and sintering powders of rare earth magnet alloys having different compositions, the energy product, coercive force, and A method for obtaining a permanent magnet having a well-balanced residual magnetic flux density has been proposed.
【０００３】この種の希土類系永久磁石は、主成分とし
て、空気中で酸化しやすい希土類元素、さらには鉄を含
んでいるため、これをそのまま使用すると酸化して錆を
発生する。そしてこの酸化物により磁気回路の特性を損
ねたり、周辺部を汚染したりする不都合が生じる。そこ
で、この希土類系磁石体の表面に保護皮膜を形成して耐
食性を付与する手段がとられている。その代表的な方法
は、磁石体の表面に光沢ニッケルめっき皮膜を形成し、
次いでクロメート処理する方法である。This type of rare earth permanent magnet contains, as a main component, a rare earth element that is easily oxidized in air, and further iron. Therefore, if it is used as it is, it will oxidize and generate rust. Then, the oxide causes problems such as impairing the characteristics of the magnetic circuit and contaminating the peripheral portion. Therefore, a measure is taken to form a protective film on the surface of the rare earth magnet to impart corrosion resistance. The typical method is to form a bright nickel plating film on the surface of the magnet body,
Then, it is a method of chromate treatment.
【０００４】[0004]
【発明が解決しようとする課題】前述の従来の表面処理
方法によると、ニッケルめっき皮膜の厚さを１６μｍ程
度以上にしないと十分な耐食性を得ることができなかっ
た。ところが、めっき皮膜を厚くすると、素材形状によ
っては膜厚の均一性が失われ、磁石の寸法精度が悪くな
るという問題がある。また、めっき皮膜を厚くするに
は、めっきに長時間を要し、それだけコスト高となる。
さらに、めっき皮膜が厚くなればなるほど、素材の形状
によっては磁気特性の劣化が起こりやすくなる。ラック
式加工方法であれば、ニッケルめっき皮膜上に六価クロ
ム浴によるめっきを施すことによって、耐食性を向上さ
せる処理方法がある。この場合、ニッケルめっき皮膜を
８μｍ程度にまで薄くすることが可能である。しかし、
バレル式加工方法の場合、六価クロム浴の付き回りがよ
くないためバレルによるめっきが困難である。According to the above-mentioned conventional surface treatment method, sufficient corrosion resistance cannot be obtained unless the thickness of the nickel plating film is about 16 μm or more. However, if the plating film is made thick, there is a problem that the uniformity of the film thickness is lost depending on the shape of the material, and the dimensional accuracy of the magnet deteriorates. Further, in order to thicken the plating film, it takes a long time for plating, and the cost becomes higher accordingly.
Furthermore, the thicker the plating film, the easier the deterioration of magnetic properties depending on the shape of the material. In the case of the rack type processing method, there is a processing method of improving corrosion resistance by plating a nickel plating film with a hexavalent chromium bath. In this case, the nickel plating film can be thinned to about 8 μm. But,
In the case of the barrel type processing method, the plating with the barrel is difficult because the hexavalent chromium bath does not adhere well.
【０００５】従って本発明は、磁石体の寸法精度を損な
うことなく、十分な耐食性を有する保護皮膜を与える磁
石の表面処理方法を提供することを目的とする。また、
本発明は、電解めっき法で処理時間を短縮できる磁石の
表面処理方法を提供することを目的とする。さらに、本
発明は、めっき皮膜を薄くすることにより、磁気特性の
劣化を少なくすることができる磁石の表面処理方法を提
供することを目的とする。Therefore, it is an object of the present invention to provide a surface treatment method for a magnet which provides a protective film having sufficient corrosion resistance without impairing the dimensional accuracy of the magnet body. Also,
An object of the present invention is to provide a surface treatment method for a magnet, which can shorten the treatment time by the electrolytic plating method. Another object of the present invention is to provide a surface treatment method for a magnet, which can reduce the deterioration of magnetic characteristics by thinning the plating film.
【０００６】[0006]
【課題を解決するための手段】本発明は、希土類系磁石
体の表面に、光沢ニッケルめっき浴を用いた電解めっき
法により光沢ニッケルめっき皮膜を形成した後、三価ク
ロム浴を用いためっき法により前記光沢ニッケルめっき
皮膜上にクロムめっき皮膜を形成し、さらにクロメート
処理することを特徴とする磁石の表面処理方法である。
ここで、めっき皮膜の膜厚は、光沢ニッケルめっき皮膜
は６〜１６μｍ、クロムめっき皮膜は０．１〜１．０μ
ｍが適当であり、さらによりよい耐食性、寸法精度、め
っき時間短縮、磁気特性劣化防止を兼ね備えた条件は、
ニッケル皮膜膜厚８〜１２μｍ、クロム皮膜膜厚０．３
〜０．８μｍである。According to the present invention, a bright nickel plating film is formed on the surface of a rare earth magnet by an electrolytic plating method using a bright nickel plating bath, and then a plating method using a trivalent chromium bath. Is used to form a chromium plating film on the bright nickel plating film, and chromate treatment is further carried out.
Here, the thickness of the plating film is 6 to 16 μm for the bright nickel plating film and 0.1 to 1.0 μ for the chrome plating film.
m is suitable, and the conditions that combine better corrosion resistance, dimensional accuracy, shortening of plating time, and prevention of deterioration of magnetic properties are as follows:
Nickel film thickness 8-12 μm, chrome film thickness 0.3
Is about 0.8 μm.
【０００７】また、本発明の表面処理方法は、希土類系
磁石体の表面に前記と同様の光沢ニッケルめっき皮膜を
形成した後、このニッケルめっき皮膜上に、錫塩および
ニッケル塩を含む錫−ニッケル浴または錫塩およびコバ
ルト塩を含む錫−コバルト浴を用いた電解めっき法によ
り、錫−ニッケル合金めっき皮膜または錫−コバルト合
金めっき皮膜を形成し、さらにクロメート処理すること
を特徴とする。上記の錫−ニッケル合金めっき皮膜を形
成する場合、ニッケル皮膜膜厚６〜１６μｍ、錫−ニッ
ケル合金皮膜膜厚０．１〜１．５μｍが適当であり、さ
らによりよい耐食性、寸法精度、めっき時間短縮、磁気
特性劣化防止を兼ね備えた条件は、ニッケル皮膜膜厚８
〜１２μｍ、錫−ニッケル合金皮膜膜厚０．４〜１．２
μｍである。In the surface treatment method of the present invention, the same bright nickel plating film as described above is formed on the surface of the rare earth magnet body, and then tin salt and tin-nickel containing nickel salt are formed on the nickel plating film. A tin-nickel alloy plating film or a tin-cobalt alloy plating film is formed by an electrolytic plating method using a bath or a tin-cobalt bath containing a tin salt and a cobalt salt, and chromate treatment is further performed. When forming the above tin-nickel alloy plating film, a nickel film thickness of 6 to 16 μm and a tin-nickel alloy film thickness of 0.1 to 1.5 μm are suitable, and further better corrosion resistance, dimensional accuracy, and plating time. The condition that combines shortening and prevention of deterioration of magnetic properties is that the nickel film thickness is 8
~ 12 μm, tin-nickel alloy film thickness 0.4-1.2
μm.
【０００８】一方、錫−コバルト合金めっき皮膜を形成
する場合は、ニッケル皮膜膜厚６〜１６μｍ、錫−コバ
ルト合金皮膜膜厚０．３〜２．０μｍが適当であり、さ
らによりよい耐食性、寸法精度、めっき時間短縮、磁気
特性劣化防止を兼ね備えた条件は、ニッケル皮膜膜厚８
〜１２μｍ、錫−コバルト合金皮膜膜厚０．６〜１．５
μｍである。本発明において、光沢ニッケルめっきに用
いるめっき浴およびめっき条件は通常のものでよい。表
１に好ましいめっき浴およびめっき条件を示す。On the other hand, when a tin-cobalt alloy plating film is formed, a nickel film thickness of 6 to 16 μm and a tin-cobalt alloy film thickness of 0.3 to 2.0 μm are suitable, and further better corrosion resistance and size. The conditions that combine accuracy, reduction of plating time, and prevention of deterioration of magnetic characteristics are nickel film thickness 8
~ 12 μm, tin-cobalt alloy film thickness 0.6-1.5
μm. In the present invention, the plating bath and plating conditions used for bright nickel plating may be ordinary ones. Table 1 shows preferred plating baths and plating conditions.
【０００９】[0009]
【表１】 [Table 1]
【００１０】また、三価クロム浴は、三価クロム塩、例
えば硫酸クロムと、錯化剤としてカルボン酸塩と、硫酸
ナトリウム、硝酸カリウムなどの電導性塩および緩衡剤
の硼酸を含むものが好ましい。代表的なめっき浴および
めっき条件を表２に示す。The trivalent chromium bath preferably contains a trivalent chromium salt, for example, chromium sulfate, a carboxylate as a complexing agent, a conductive salt such as sodium sulfate and potassium nitrate, and a buffering agent, boric acid. . Table 2 shows typical plating baths and plating conditions.
【００１１】[0011]
【表２】 [Table 2]
【００１２】次に、錫−ニッケル合金めっきおよび錫−
コバルト合金めっきのためのめっき浴、めっき条件の好
ましい例を表３および表４に示す。Next, tin-nickel alloy plating and tin-
Tables 3 and 4 show preferable examples of plating baths and plating conditions for cobalt alloy plating.
【００１３】[0013]
【表３】 [Table 3]
【００１４】[0014]
【表４】 [Table 4]
【００１５】なお、本発明の光沢ニッケルめっきに先立
って行う磁石体の前処理は、通常のものでよく、アルカ
リ脱脂および酸洗いをし、さらに希硫酸による活性化処
理をするのが好ましい。The pretreatment of the magnet body prior to the bright nickel plating of the present invention may be a conventional one, preferably alkali degreasing and pickling, and further activation treatment with dilute sulfuric acid.
【００１６】[0016]
【作用】光沢ニッケルめっき皮膜上に、三価クロム浴を
用いた電解めっきによりクロム皮膜を形成することによ
り、極めて薄く、しかも均一性の優れたクロム皮膜を形
成することができる。このため耐食性を向上することが
できるので、光沢ニッケルめっき皮膜を従来のように厚
くする必要がなく、従って磁石の寸法精度をよくするこ
とができる。クロムめっきをするには、六価クロム浴が
よく知られている。六価クロム浴を用いると、耐食性の
優れた皮膜を得ることはできるが、付きまわり性が悪
く、焼けを起こすという短所を有し、しかもバレルめっ
きをすることができない。さらに、公害の問題があり、
特別な排水処理を要するのでコスト高となる。これに対
して、三価クロム浴を用いると、これらの問題をすべて
解決し、バレルを用いてニッケルめっき皮膜上にクロム
めっきをすることができる。このクロムめっきにより耐
食性が格段によくなるので、ニッケルめっき皮膜を従来
より薄くすることができる。ニッケルめっき皮膜を薄く
すると、角部と平坦部の膜厚差が少なくなり、より寸法
精度がよくなるのである。磁石の寸法精度がよくなれ
ば、例えばハードディスクなどを駆動する駆動系制御の
精度がより向上する。また、ニッケルめっき皮膜の膜厚
を薄くすることにより、めっき時間を短縮することがで
きる。[Function] By forming a chromium film on the bright nickel plating film by electrolytic plating using a trivalent chromium bath, a very thin and highly uniform chromium film can be formed. Therefore, since the corrosion resistance can be improved, it is not necessary to make the bright nickel plating film thick as in the conventional case, and therefore the dimensional accuracy of the magnet can be improved. Hexavalent chromium baths are well known for chromium plating. When a hexavalent chromium bath is used, a coating having excellent corrosion resistance can be obtained, but it has the disadvantages of poor throwing power and burning, and cannot be barrel plated. In addition, there are pollution problems,
The cost is high because special wastewater treatment is required. On the other hand, if a trivalent chromium bath is used, all of these problems can be solved and the barrel can be used to perform chromium plating on the nickel plating film. Corrosion resistance is remarkably improved by this chrome plating, so that the nickel plating film can be made thinner than before. When the nickel plating film is thinned, the difference in film thickness between the corners and the flat part is reduced, and the dimensional accuracy is improved. If the dimensional accuracy of the magnet is improved, the accuracy of drive system control for driving, for example, a hard disk is further improved. Further, the plating time can be shortened by reducing the thickness of the nickel plating film.
【００１７】上記のクロムめっきの代わりに錫−ニッケ
ル合金めっきまたは錫−コバルト合金めっきをしてもク
ロムめっきをしたものに近い耐食性を得ることができ
る。前記表３に示すめっき浴およびめっき条件によりＳ
ｎ含量６５〜７５重量％、膜厚０．１〜１．５μｍの錫
−ニッケル合金めっき皮膜を得ることができる。この皮
膜は、クロムめっき皮膜とほぼ同等の耐食性を示す。付
きまわりはクロムよりよく、バレルめっきが可能であ
る。また、表４に示すめっき浴およびめっき条件により
Ｃｏの含量２０〜３０重量％の錫−コバルト合金めっき
皮膜を得ることができる。耐食性はクロムめっきに比べ
若干落ちるが、付きまわりはよく、バレルめっきおよび
めっき時間の短縮が可能である。Even if tin-nickel alloy plating or tin-cobalt alloy plating is used instead of the above chromium plating, corrosion resistance close to that of chromium plating can be obtained. S depends on the plating bath and plating conditions shown in Table 3 above.
A tin-nickel alloy plating film having an n content of 65 to 75% by weight and a film thickness of 0.1 to 1.5 μm can be obtained. This film exhibits corrosion resistance almost equal to that of the chromium plating film. The attachment is better than chrome and barrel plating is possible. Further, a tin-cobalt alloy plating film having a Co content of 20 to 30 wt% can be obtained by the plating bath and plating conditions shown in Table 4. Corrosion resistance is slightly lower than that of chrome plating, but the adhesion is good and barrel plating and plating time can be shortened.
【００１８】[0018]
【実施例】以下、本発明の実施例を説明する。なお、以
下の実施例では、本発明の効果が最もよく表れるバレル
式加工方法について説明するが、本発明は、ラック式加
工方法に適用しても同様な効果が得られることは言うま
でもない。 ［実施例１］図１に示す形状の大きさ３ｃｍ×６ｃｍ、
厚さ約２ｍｍのネオジウム−鉄−硼素系焼結永久磁石に
ついて、まず６０ｇ／ｌのＮａＯＨおよび界面活性剤を
含む５０℃のアルカリ水溶液に１０分間浸漬して脱脂を
した後、３０℃の塩酸水溶液（１モル／ｌ）に１分間浸
漬する酸洗いにより酸化皮膜を除去し、水で超音波洗浄
し、さらに５０℃の硫酸水溶液（０．５モル／ｌ）に３
０秒間浸漬して活性化処理をし、水で超音波洗浄する。
こうして前処理した磁石を鉄製ダミーの玉とともにバレ
ルに入れ、表５に示すめっき浴およびめっき条件を用い
て各種膜厚の光沢ニッケルめっき皮膜を形成する。な
お、皮膜の厚さは、めっき時間を変えることにより調整
する。EXAMPLES Examples of the present invention will be described below. In addition, although the barrel type processing method in which the effects of the present invention are best shown will be described in the following examples, it is needless to say that the same effects can be obtained by applying the present invention to a rack type processing method. Example 1 The size of the shape shown in FIG. 1 was 3 cm × 6 cm,
A neodymium-iron-boron-based sintered permanent magnet having a thickness of about 2 mm was first immersed in an alkaline aqueous solution containing 60 g / l of NaOH and a surfactant at 50 ° C. for 10 minutes for degreasing, and then a hydrochloric acid aqueous solution at 30 ° C. The oxide film is removed by pickling, which is soaked in (1 mol / l) for 1 minute, ultrasonically washed with water, and further immersed in a sulfuric acid aqueous solution (0.5 mol / l) at 50 ° C.
It is dipped for 0 seconds to be activated, and ultrasonically washed with water.
The magnet thus pretreated is put in a barrel together with an iron dummy ball, and a bright nickel plating film of various thicknesses is formed using the plating bath and plating conditions shown in Table 5. The thickness of the film is adjusted by changing the plating time.
【００１９】[0019]
【表５】 [Table 5]
【００２０】次に、水洗の後、表６に示すめっき浴を用
いて各種膜厚のクロムめっき皮膜を形成する。なお、皮
膜の厚さは、めっき時間を変えることにより調整する。Next, after washing with water, chromium plating films of various thicknesses are formed using the plating baths shown in Table 6. The thickness of the film is adjusted by changing the plating time.
【００２１】[0021]
【表６】 [Table 6]
【００２２】上記のニッケルめっき皮膜とクロムめっき
皮膜を形成した磁石およびニッケルめっき皮膜のみを形
成した磁石をそれぞれ４０℃の無水クロム酸水溶液（１
０ｇ／ｌ）に３分間浸漬してクロメート処理を施す。以
上のようにして表面処理を施した磁石の保護皮膜につい
てＪＩＳ Ｈ８５０２に規定のキャス試験をして評価し
た。このキャス試験は、塩化ナトリウム４０ｇ／ｌおよ
び塩化第二銅０．２０ｇ／ｌを含む酢酸酸性の水溶液を
圧縮空気圧力０．７〜１．７ｋｇｆ／ｃｍ2で１．０〜
２．０ｍｌ／８０ｃｍ2／ｈの割合で噴霧している温度
５０℃の試験槽内に１６時間放置してめっきの耐食性を
調べる試験方法であり、試験後の試料とレイティングＮ
ｏ．標準図形との目視による照合により、以下の基準で
判定するものである。レイティングＮｏ．９．５以上：
◎、レイティングＮｏ．９以上：○、レイティングＮ
ｏ．７以上：△、レイティングＮｏ．７未満：×。判定
結果を表７に示す。また、ニッケルめっきおよびクロム
めっきに要した時間の比較を表８に示す。The above-mentioned magnet having a nickel plating film and a chromium plating film formed thereon and a magnet having only a nickel plating film formed thereon were treated with a chromic anhydride aqueous solution (1
Chromate treatment by immersing in 0 g / l) for 3 minutes. With respect to the protective film of the magnet which has been subjected to the surface treatment as described above, a Cass test prescribed in JIS H8502 was performed and evaluated. In this Cass test, an acetic acid acidic aqueous solution containing 40 g / l of sodium chloride and 0.20 g / l of cupric chloride was compressed to 1.0 to 1.0 at a compressed air pressure of 0.7 to 1.7 kgf / cm 2 .
It is a test method for examining the corrosion resistance of plating by leaving it in a test tank at a temperature of 50 ° C. sprayed at a rate of 2.0 ml / 80 cm 2 / h for 16 hours.
o. It is judged by the following criteria by visual comparison with a standard figure. Rating No. 9.5 and above:
◎, Rating No. 9 or higher: ○, rating N
o. 7 or higher: Δ, rating No. Less than 7: x. The judgment results are shown in Table 7. Table 8 shows a comparison of the time required for nickel plating and chromium plating.
【００２３】[0023]
【表７】 [Table 7]
【００２４】[0024]
【表８】 [Table 8]
【００２５】表７の結果から明らかなように、ニッケル
めっき皮膜上に膜厚約０．５μｍのクロムめっき皮膜を
形成すると、ニッケルめっきは膜厚８μｍで十分な耐食
性を得ることができる。クロムめっきの膜厚をさらに厚
くすれば、ニッケルめっきの膜厚を減らすことができ
る。しかし、クロムめっきの膜厚を大きくすると、引張
応力が働き剥がれやくすなるので、１μｍ程度が限度で
ある。クロムめっきの膜厚を０．５μｍ程度にするな
ら、ニッケルめっきの膜厚は６μｍ程度でもほぼ満足で
きる耐食性を得ることができる。また、ニッケルめっき
の膜厚を１２μｍ程度にすると、クロムめっきの膜厚
０．１μｍ程度でほぼ満足できる耐食性を得られる。ニ
ッケルめっき皮膜上にクロムめっき皮膜を形成すること
により、耐食性が得られると判断できる膜厚は、ニッケ
ルめっき皮膜が６〜１６μｍ、クロムめっき皮膜が０．
１〜１．０μｍであり、さらに良い耐食性を得られる膜
厚は、ニッケルめっき皮膜が８〜１２μｍ、クロムめっ
き皮膜が０．３〜０．８μｍである。従来の光沢ニッケ
ルめっきとクロメート処理により十分な耐食性を得るに
はニッケルめっきの膜厚は１６μｍを要し、そのために
はめっき時間約１６０分を要する。これに対して、ニッ
ケルめっき上にクロムめっきする本発明の方法による
と、膜厚８μｍのニッケルめっき（めっき時間約８０
分）、膜厚０．５μｍのクロムめっき（めっき時間約５
分）と約半分の膜厚８．５μｍおよび約半分のめっき時
間８５分で十分な耐食性を得ることができる。As is clear from the results in Table 7, when a chromium plating film having a thickness of about 0.5 μm is formed on the nickel plating film, the nickel plating can obtain sufficient corrosion resistance with a film thickness of 8 μm. If the thickness of the chromium plating is increased, the thickness of the nickel plating can be reduced. However, when the thickness of the chrome plating is increased, tensile stress acts and peels off easily, so the limit is about 1 μm. If the thickness of the chromium plating is about 0.5 μm, even if the thickness of the nickel plating is about 6 μm, almost satisfactory corrosion resistance can be obtained. Further, if the thickness of the nickel plating is about 12 μm, almost satisfactory corrosion resistance can be obtained with the thickness of the chromium plating of about 0.1 μm. By forming a chromium plating film on the nickel plating film, it can be determined that corrosion resistance can be obtained. The nickel plating film has a thickness of 6 to 16 μm, and the chromium plating film has a thickness of 0.
The film thickness is 1 to 1.0 μm, and the film thickness that can obtain better corrosion resistance is 8 to 12 μm for the nickel plating film and 0.3 to 0.8 μm for the chromium plating film. In order to obtain sufficient corrosion resistance by the conventional bright nickel plating and chromate treatment, the nickel plating requires a film thickness of 16 μm, which requires a plating time of about 160 minutes. On the other hand, according to the method of the present invention in which chromium plating is performed on nickel plating, nickel plating having a film thickness of 8 μm (plating time of about 80
Min), chromium plating with a film thickness of 0.5 μm (plating time approximately 5
Min), a film thickness of about half, 8.5 μm, and a plating time of about half, 85 minutes, can provide sufficient corrosion resistance.
【００２６】上記に用いた膜厚は、最も薄い部分の膜厚
を基準としたもので、図１に示すような形状の磁石にバ
レルめっきした場合、通常は図１における磁石の下側の
Ａ点における膜厚がこれに相当する。また、Ｃ点におけ
る膜厚が最も厚くなる。表９に、各種膜厚の光沢ニッケ
ルめっきをしたときの最も薄い部分および最も厚い部分
の膜厚を示す。The film thickness used above is based on the film thickness of the thinnest portion, and when a magnet having a shape as shown in FIG. 1 is barrel-plated, A on the lower side of the magnet in FIG. 1 is usually used. The film thickness at the point corresponds to this. Further, the film thickness at the point C becomes the largest. Table 9 shows the film thicknesses of the thinnest part and the thickest part when bright nickel plating of various film thicknesses is performed.
【００２７】[0027]
【表９】 [Table 9]
【００２８】ニッケルめっきのみで耐食性を得るため
に、最も薄い部分で１６μｍ付けると、最も厚い部分で
は８０μｍ位付いてしまうことになり、その差は６４μ
ｍとなる。しかし、クロムめっきをすることにより、最
も薄い部分で８μｍ程度で済み、最も厚い部分で２４μ
ｍ位にすることができる。その差は１６μｍである。以
上のように、三価クロム浴を用いた電解めっき法により
光沢ニッケルめっき皮膜上にクロムめっき皮膜を形成す
ることにより、耐食性と寸法精度の優れた保護皮膜を有
する磁石を得ることができる。If 16 μm is applied to the thinnest part in order to obtain corrosion resistance only by nickel plating, it will be about 80 μm in the thickest part, the difference being 64 μm.
m. However, by plating with chrome, the thinnest part needs to be about 8 μm and the thickest part is 24 μm.
It can be in the m position. The difference is 16 μm. As described above, by forming the chromium plating film on the bright nickel plating film by the electrolytic plating method using the trivalent chromium bath, it is possible to obtain a magnet having a protective film having excellent corrosion resistance and dimensional accuracy.
【００２９】以下に、三価クロム浴の特徴を挙げる。 （１）六価クロム浴に比べ、電流量が約半分で済む。 （２）低電流部分への付き回りが良好である。従って、
バレルメッキが可能である。 （３）均一電着性が非常に良く、低電流部、高電流部の
膜厚差がほとんど生じない。 （４）めっき液中のクロム含有量が、三価クロムとして
少ないため、人体への影響がほとんどない。 （５）高電流部分での焼けがほとんど生じない。 （６）廃水処理が容易である。 （７）ある膜厚範囲内であれば六価クロムと変わらない
耐食性を示す。The characteristics of the trivalent chromium bath are listed below. (1) The amount of current required is about half that of a hexavalent chromium bath. (2) Good coverage to the low current portion. Therefore,
Barrel plating is possible. (3) Uniform throwing power is very good, and there is almost no difference in film thickness between the low current portion and the high current portion. (4) Since the chromium content in the plating solution is low as trivalent chromium, it has almost no effect on the human body. (5) Burning hardly occurs in the high current portion. (6) Wastewater treatment is easy. (7) Within a certain film thickness range, it exhibits corrosion resistance similar to hexavalent chromium.
【００３０】［実施例２］クロムめっきの代わりに錫−
ニッケル合金めっきをする例を説明する。錫−ニッケル
めっき浴を表１０に示す。[Example 2] Tin instead of chrome plating
An example of nickel alloy plating will be described. The tin-nickel plating bath is shown in Table 10.
【００３１】[0031]
【表１０】 [Table 10]
【００３２】光沢ニッケルめっき皮膜と錫−ニッケル合
金めっき皮膜を形成した後、クロメート処理を施す。こ
うして表面処理を施した磁石の保護皮膜について、実施
例１と同様にしてキャス試験をして評価した結果を表１
１に示す。また、ニッケルめっきおよび錫−ニッケル合
金めっきに要した時間の比較を表１２に示す。After forming the bright nickel plating film and the tin-nickel alloy plating film, chromate treatment is performed. With respect to the protective coating of the magnet thus surface-treated, a cass test was conducted in the same manner as in Example 1, and the results are shown in Table 1.
Shown in 1. Table 12 shows a comparison of the time required for nickel plating and tin-nickel alloy plating.
【００３３】[0033]
【表１１】 [Table 11]
【００３４】[0034]
【表１２】 [Table 12]
【００３５】クロムめっきの代わりに錫−ニッケル合金
めっきをする場合は、表１１からも明らかなように、光
沢ニッケルめっきの膜厚を若干厚くすることが望まし
い。錫−ニッケル合金めっきの膜厚を０．８μｍ程度に
すると、ニッケルめっきの膜厚６μｍ程度でほぼ満足で
きる耐食性を得ることができ、ニッケルめっきの膜厚８
μｍで十分な耐食性を得ることができる。また、ニッケ
ルめっきの膜厚を１２μｍ程度にすると、錫−ニッケル
合金めっきの膜厚０．１μｍ程度でほぼ満足できる耐食
性を得ることができる。ニッケルめっき皮膜上に錫−ニ
ッケル合金めっき皮膜を形成することにより、耐食性が
得られると判断できる膜厚は、ニッケルめっき皮膜が６
〜１６μｍ、錫−ニッケル合金めっき皮膜が０．１〜
１．５μｍであり、さらに良い耐食性を得られる膜厚
は、ニッケルめっき皮膜が８〜１２μｍ、錫−ニッケル
合金めっき皮膜が０．４〜１．２μｍである。従来のニ
ッケルめっきのみを膜厚１６μｍ形成したものと同等の
耐食性を得るには、ニッケルめっき皮膜８μｍ（めっき
時間８０分）および錫−ニッケル合金めっき皮膜０．８
μｍ（めっき時間６分）と膜厚、めっき時間ともに約半
分となる。When tin-nickel alloy plating is used instead of chrome plating, it is desirable to increase the thickness of the bright nickel plating a little, as is apparent from Table 11. When the thickness of the tin-nickel alloy plating is set to about 0.8 μm, almost satisfactory corrosion resistance can be obtained with the thickness of the nickel plating of about 6 μm.
With μm, sufficient corrosion resistance can be obtained. Further, when the nickel plating film thickness is about 12 μm, substantially satisfactory corrosion resistance can be obtained with the tin-nickel alloy plating film thickness of about 0.1 μm. By forming a tin-nickel alloy plating film on the nickel plating film, it can be judged that corrosion resistance can be obtained.
~ 16μm, tin-nickel alloy plating film 0.1 ~
The thickness is 1.5 μm, and the film thickness that can obtain better corrosion resistance is 8 to 12 μm for the nickel plating film and 0.4 to 1.2 μm for the tin-nickel alloy plating film. In order to obtain the same corrosion resistance as that obtained by forming the conventional nickel plating only with a film thickness of 16 μm, the nickel plating film 8 μm (plating time 80 minutes) and the tin-nickel alloy plating film 0.8
μm (plating time 6 minutes) and film thickness and plating time are about half.
【００３６】以下、錫−ニッケル合金めっき浴の特徴を
挙げる。 （１）低電流部分への付き回りが良好である。従って、
バレルメッキが可能である。 （２）均一電着性が非常に良く、低電流部、高電流部の
膜厚差がほとんど生じない。 （３）浴中の錫−ニッケル比率が多少変動しても、析出
比率が大きく変動することがなく、浴管理が容易であ
る。 （４）同じ膜厚の場合耐食性はクロムに比べ若干落ちる
が、電流効率の良さから厚付けができ、耐食性もほぼ同
等になる。 （５）クロムに比べ、耐食性が保てる膜厚範囲が広い。 （６）廃水処理が容易である。The characteristics of the tin-nickel alloy plating bath will be given below. (1) Good coverage to the low current portion. Therefore,
Barrel plating is possible. (2) Uniform throwing power is very good, and there is almost no difference in film thickness between the low current portion and the high current portion. (3) Even if the tin-nickel ratio in the bath fluctuates to some extent, the precipitation ratio does not fluctuate significantly, and bath management is easy. (4) When the film thickness is the same, the corrosion resistance is slightly lower than that of chromium, but because of the good current efficiency, it can be thickened and the corrosion resistance is almost the same. (5) Compared with chromium, it has a wider film thickness range where corrosion resistance can be maintained. (6) Wastewater treatment is easy.
【００３７】［実施例３］クロムめっきの代わりに錫−
コバルト合金めっきをする例を説明する。錫−コバルト
合金めっき浴およびめっき条件を表１３に示す。Example 3 Tin-instead of chrome plating
An example of cobalt alloy plating will be described. Table 13 shows the tin-cobalt alloy plating bath and plating conditions.
【００３８】[0038]
【表１３】 [Table 13]
【００３９】光沢ニッケルめっき皮膜と錫−コバルト合
金めっき皮膜を形成した後、クロメート処理を施す。こ
うして表面処理を施した磁石の保護皮膜について、実施
例１と同様にしてキャス試験をして評価した結果を表１
４に示す。また、ニッケルめっきおよび錫−コバルト合
金めっきに要した時間の比較を表１５に示す。After forming the bright nickel plating film and the tin-cobalt alloy plating film, chromate treatment is performed. With respect to the protective coating of the magnet thus surface-treated, a cass test was conducted in the same manner as in Example 1, and the results are shown in Table 1.
4 shows. Table 15 shows a comparison of the times required for nickel plating and tin-cobalt alloy plating.
【００４０】[0040]
【表１４】 [Table 14]
【００４１】[0041]
【表１５】 [Table 15]
【００４２】クロムめっきの代わりに錫−コバルト合金
めっきをする場合は、表１４からも明らかなように、光
沢ニッケルめっきの膜厚を若干厚くすることが望まし
い。錫−コバルト合金めっきの膜厚を１．０μｍ程度に
すると、ニッケルめっきの膜厚６μｍ程度でほぼ満足で
きる耐食性を得ることができ、ニッケルめっきの膜厚８
μｍで十分な耐食性を得ることができる。また、ニッケ
ルめっきの膜厚を１２μｍ程度にすると、錫−コバルト
合金めっきの膜厚０．３μｍ程度でほぼ満足できる耐食
性を得ることができる。ニッケルめっき皮膜上に錫−コ
バルト合金めっき皮膜を形成することにより、耐食性が
得られると判断できる膜厚は、ニッケルめっき皮膜が６
〜１６μｍ、錫−コバルト合金めっき皮膜が０．３〜
２．０μｍであり、さらに良い耐食性を得られる膜厚
は、ニッケルめっき皮膜が８〜１２μｍ、錫−コバルト
合金めっき皮膜が０．６〜１．５μｍである。従来のニ
ッケルめっきのみを膜厚１６μｍ形成したものと同等の
耐食性を得るには、ニッケルめっき皮膜８μｍ（めっき
時間８０分）および錫−コバルト合金めっき皮膜１．０
μｍ（めっき時間３分）と膜厚、めっき時間とも約半分
となる。When tin-cobalt alloy plating is used instead of chrome plating, it is desirable to increase the thickness of the bright nickel plating a little, as is clear from Table 14. When the thickness of the tin-cobalt alloy plating is about 1.0 μm, almost satisfactory corrosion resistance can be obtained with the thickness of nickel plating of about 6 μm.
With μm, sufficient corrosion resistance can be obtained. Further, when the nickel plating film thickness is about 12 μm, almost satisfactory corrosion resistance can be obtained with the tin-cobalt alloy plating film thickness of about 0.3 μm. By forming a tin-cobalt alloy plating film on the nickel plating film, it can be judged that corrosion resistance can be obtained.
~ 16μm, tin-cobalt alloy plating film 0.3 ~
The film thickness is 2.0 μm, and the film thickness with which better corrosion resistance can be obtained is 8 to 12 μm for the nickel plating film and 0.6 to 1.5 μm for the tin-cobalt alloy plating film. In order to obtain the same corrosion resistance as that obtained by forming the conventional nickel plating only with a film thickness of 16 μm, the nickel plating film 8 μm (plating time 80 minutes) and the tin-cobalt alloy plating film 1.0
μm (plating time 3 minutes), film thickness and plating time are about half.
【００４３】以下、錫−コバルト合金めっき浴の特徴を
挙げる。 （１）低電流部分への付き回りが良好である。従って、
バレルメッキが可能である。 （２）均一電着性が非常に良く、低電流部、高電流部の
膜厚差がほとんど生じない。 （３）電流密度の差による析出比率への影響をほとんど
受けない。 （４）同じ膜厚の場合耐食性はクロムに比べ落ちるが、
電流効率がクロムの約２倍であり厚づけによる耐食性が
良い。 （５）クロムに比べ、耐食性が保てる膜厚範囲が広い。 （６）廃水処理が容易である。The characteristics of the tin-cobalt alloy plating bath will be described below. (1) Good coverage to the low current portion. Therefore,
Barrel plating is possible. (2) Uniform throwing power is very good, and there is almost no difference in film thickness between the low current portion and the high current portion. (3) There is almost no effect on the precipitation ratio due to the difference in current density. (4) When the film thickness is the same, the corrosion resistance is lower than that of chromium,
The current efficiency is about twice that of chromium, and the corrosion resistance by thickening is good. (5) Compared with chromium, it has a wider film thickness range where corrosion resistance can be maintained. (6) Wastewater treatment is easy.
【００４４】［実施例４］永久磁石は、組成、形状によ
って差はあるが、高温雰囲気中で放置試験を行うと磁気
特性の劣化が起こる。その劣化を調べる方法として、高
温放置（１２０℃、２４時間）前後において保磁力およ
び残留磁束密度がどのように変化したかをみる方法があ
る。本実施例では、劣化が現われやすい小形磁石（大き
さ２×２ｍｍ、厚み０．７ｍｍ）について、ニッケルめ
っきの膜厚と磁気特性の劣化率との関係を調べた。すな
わち、上記寸法のネオジウムー鉄ー硼素系焼結永久磁石
について、実施例１と同様にして所定の前処理の後、各
種膜厚の光沢ニッケルめっき皮膜を形成し、さらに膜厚
０．５μｍのクロムめっきとクロメート処理を施したも
のを試料とし、高温放置による磁気特性の劣化率を調べ
た。図２において、ａを高温放置前の減磁曲線、ｂを高
温放置後の減磁曲線とすると、劣化率は次式で表され
る。 劣化率（％）＝（ＯＰ1−ＯＰ2）／ＯＰ1×１００ ニッケルめっき皮膜の膜厚と劣化率との関係を表１６に
示す。[Embodiment 4] Permanent magnets differ in composition and shape, but when left to stand in a high temperature atmosphere, their magnetic properties deteriorate. As a method of investigating the deterioration, there is a method of observing how the coercive force and the residual magnetic flux density change before and after high temperature standing (120 ° C., 24 hours). In this example, the relationship between the nickel plating film thickness and the deterioration rate of the magnetic characteristics was examined for a small magnet (size 2 × 2 mm, thickness 0.7 mm) that is likely to deteriorate. That is, with respect to the neodymium-iron-boron-based sintered permanent magnet having the above-mentioned size, after performing a predetermined pretreatment in the same manner as in Example 1, a bright nickel plating film having various film thicknesses is formed, and a chromium film having a film thickness of 0.5 μm is formed. Using a sample that had been plated and chromated, the deterioration rate of the magnetic properties due to high temperature storage was investigated. In FIG. 2, letting a be a demagnetization curve before being left at high temperature and b being a demagnetization curve after being left at high temperature, the deterioration rate is expressed by the following equation. Deterioration rate (%) = (OP 1 −OP 2 ) / OP 1 × 100 Table 16 shows the relationship between the film thickness of the nickel plating film and the deterioration rate.
【００４５】[0045]
【表１６】 [Table 16]
【００４６】磁気特性の劣化は、現在のところ、光沢ニ
ッケルめっき浴中の塩素イオンがエッチングされた素材
表面に残り、素材表面を浸食することによって物性が変
化することが最大の原因と考えられている。めっき膜厚
が薄い初期段階では、皮膜表面にピンホールが多く見ら
れ、めっきが進行し膜厚が厚くなるに従ってそのピンホ
ールは徐々に埋められていく。埋められたピンホールに
塩素イオンが残渣となって素材表面を浸食し、劣化を起
こす。つまり、膜厚が厚くなればなるほど劣化が進み、
ピンホールがほぼ埋められる程度の膜厚（１６以上）で
磁気特性の劣化が最大となっている。クロムめっきの代
りに錫ーニッケル合金めっきまたは錫ーコバルト合金め
っきをしても上記と同様な結果を与える。このように、
本発明によれば、ニッケルめっき皮膜の膜厚をある程度
薄くすることが可能となるため、ピンホール中の塩素イ
オンが水洗によって取り除かれやすくなり、磁気特性の
劣化を抑制することができる。At present, it is considered that the deterioration of magnetic properties is caused most by the fact that chlorine ions in the bright nickel plating bath remain on the etched material surface and the physical properties are changed by eroding the material surface. There is. In the initial stage where the plating film thickness is thin, many pinholes are seen on the film surface, and the pinholes are gradually filled as the plating progresses and the film thickness increases. Chloride ions are left as residues in the buried pinholes, eroding the material surface and causing deterioration. In other words, as the film thickness increases, the deterioration progresses,
Degradation of magnetic characteristics is maximized when the film thickness (16 or more) is such that the pinholes are almost completely filled. Even if tin-nickel alloy plating or tin-cobalt alloy plating is used instead of chromium plating, the same result as above is obtained. in this way,
According to the present invention, since it is possible to reduce the thickness of the nickel plating film to some extent, chlorine ions in the pinholes are easily removed by washing with water, and deterioration of magnetic characteristics can be suppressed.
【００４７】[0047]
【発明の効果】以上のように本発明の方法によれば、高
性能を保有する永久磁石を得ることができるものであ
る。さらに本発明によれば、光沢ニッケルめっき皮膜を
従来より薄くすることができるので、保護皮膜の均一性
を向上し、それによって永久磁石の寸法精度を良くする
ことができるとともに表面処理の時間を短縮することが
できる。また、保存による磁気特性の劣化を抑制するこ
とができる。As described above, according to the method of the present invention, a permanent magnet having high performance can be obtained. Furthermore, according to the present invention, since the bright nickel plating film can be made thinner than before, the uniformity of the protective film can be improved, thereby improving the dimensional accuracy of the permanent magnet and shortening the surface treatment time. can do. In addition, it is possible to suppress deterioration of magnetic characteristics due to storage.
【図１】本発明の実施例に用いた永久磁石の平面図であ
る。FIG. 1 is a plan view of a permanent magnet used in an example of the present invention.
【図２】永久磁石の減磁曲線の例を示す。FIG. 2 shows an example of a demagnetization curve of a permanent magnet.
Claims (6)
ケルめっき浴による電解めっき法で光沢ニッケルめっき
皮膜を形成した後、三価クロム浴による電解めっき法で
前記光沢ニッケルめっき皮膜上にクロムめっき皮膜を形
成し、さらにクロメート処理することを特徴とする永久
磁石の表面処理方法。1. A bright nickel plating film is formed on the surface of a rare earth-based permanent magnet body by an electrolytic plating method using a bright nickel plating bath, and then chromium plating is performed on the bright nickel plating film by an electrolytic plating method using a trivalent chromium bath. A surface treatment method for a permanent magnet, which comprises forming a film and further subjecting it to a chromate treatment.
μｍ、クロムめっき皮膜を０．１〜１．０μｍ形成する
請求項１記載の永久磁石の表面処理方法。2. The bright nickel plating film having a thickness of 6 to 16
The method for surface treatment of a permanent magnet according to claim 1, wherein the coating film has a thickness of 0.1 μm and a chromium plating film of 0.1 to 1.0 μm.
ケルめっき浴による電解めっき法で光沢ニッケルめっき
皮膜を形成した後、錫塩およびニッケル塩を含む錫−ニ
ッケル浴による電解めっき法で前記光沢ニッケルめっき
皮膜上に錫−ニッケル合金めっき皮膜を形成し、さらに
クロメート処理することを特徴とする永久磁石の表面処
理方法。3. A bright nickel plating film is formed on the surface of a rare earth-based permanent magnet body by an electrolytic plating method using a bright nickel plating bath, and then the bright plating is performed by an electrolytic plating method using a tin-nickel bath containing tin salt and nickel salt. A surface treatment method for a permanent magnet, which comprises forming a tin-nickel alloy plating film on a nickel plating film, and further performing chromate treatment.
μｍ、錫−ニッケル合金めっき皮膜を０．１〜１．５μ
ｍ形成する請求項３記載の永久磁石の表面処理方法。4. The bright nickel plating film having a thickness of 6 to 16
μm, tin-nickel alloy plating film 0.1-1.5μ
The method for surface treatment of a permanent magnet according to claim 3, wherein the surface treatment is performed.
ルめっき浴による電解めっき法で光沢ニッケルめっき皮
膜を形成した後、錫塩およびコバルト塩を含む錫−コバ
ルト浴による電解めっき法で前記光沢ニッケルめっき皮
膜上に錫−コバルト合金めっき皮膜を形成し、さらにク
ロメート処理することを特徴とする永久磁石の表面処理
方法。5. A bright nickel plating film is formed on the surface of a rare earth permanent magnet body by an electrolytic plating method using a bright nickel plating bath, and the bright nickel is then plated by a tin-cobalt bath containing a tin salt and a cobalt salt. A surface treatment method for a permanent magnet, which comprises forming a tin-cobalt alloy plating film on the plating film, and further performing chromate treatment.
μｍ、錫−コバルト合金めっき皮膜を０．３〜２．０μ
ｍ形成する請求項５記載の永久磁石の表面処理方法。6. The bright nickel plating film having a thickness of 6 to 16
μm, tin-cobalt alloy plating film 0.3-2.0μ
6. The surface treatment method for a permanent magnet according to claim 5, wherein m is formed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5266210A JP2831244B2 (en) | 1993-10-25 | 1993-10-25 | Surface treatment method for permanent magnet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5266210A JP2831244B2 (en) | 1993-10-25 | 1993-10-25 | Surface treatment method for permanent magnet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07135121A true JPH07135121A (en) | 1995-05-23 |
| JP2831244B2 JP2831244B2 (en) | 1998-12-02 |
Family
ID=17427796
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5266210A Expired - Lifetime JP2831244B2 (en) | 1993-10-25 | 1993-10-25 | Surface treatment method for permanent magnet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2831244B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0965622A (en) * | 1995-08-23 | 1997-03-07 | Hitachi Metals Ltd | Parts for high-efficiency rotor and rotor |
| JP2009072725A (en) * | 2007-09-21 | 2009-04-09 | Aaju:Kk | Magnetic treatment apparatus of fluid |
| JP2012082475A (en) * | 2010-10-12 | 2012-04-26 | Okuno Chemical Industries Co Ltd | Trivalent chromium plating method by barrel plating |
| JP2015158201A (en) * | 2014-02-21 | 2015-09-03 | プファイファー・ヴァキューム・ゲーエムベーハー | vacuum pump |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01223711A (en) * | 1988-03-03 | 1989-09-06 | Sumitomo Special Metals Co Ltd | Manufacture of corrosion-resistant permanent magnet |
| JPH01304713A (en) * | 1988-06-02 | 1989-12-08 | Shin Etsu Chem Co Ltd | Manufacture of corrosion-resistant rare earth magnet |
-
1993
- 1993-10-25 JP JP5266210A patent/JP2831244B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01223711A (en) * | 1988-03-03 | 1989-09-06 | Sumitomo Special Metals Co Ltd | Manufacture of corrosion-resistant permanent magnet |
| JPH01304713A (en) * | 1988-06-02 | 1989-12-08 | Shin Etsu Chem Co Ltd | Manufacture of corrosion-resistant rare earth magnet |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0965622A (en) * | 1995-08-23 | 1997-03-07 | Hitachi Metals Ltd | Parts for high-efficiency rotor and rotor |
| JP2009072725A (en) * | 2007-09-21 | 2009-04-09 | Aaju:Kk | Magnetic treatment apparatus of fluid |
| JP2012082475A (en) * | 2010-10-12 | 2012-04-26 | Okuno Chemical Industries Co Ltd | Trivalent chromium plating method by barrel plating |
| JP2015158201A (en) * | 2014-02-21 | 2015-09-03 | プファイファー・ヴァキューム・ゲーエムベーハー | vacuum pump |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2831244B2 (en) | 1998-12-02 |
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