JPH08176891A - Surface treatment of stainless steel - Google Patents
Surface treatment of stainless steelInfo
- Publication number
- JPH08176891A JPH08176891A JP32444994A JP32444994A JPH08176891A JP H08176891 A JPH08176891 A JP H08176891A JP 32444994 A JP32444994 A JP 32444994A JP 32444994 A JP32444994 A JP 32444994A JP H08176891 A JPH08176891 A JP H08176891A
- Authority
- JP
- Japan
- Prior art keywords
- stainless steel
- treatment
- corrosion resistance
- ammonium molybdate
- steel members
- 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.)
- Withdrawn
Links
Landscapes
- Chemical Treatment Of Metals (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ステンレス鋼に電解処
理を施すことにより、表面光沢を殆ど損なうことなく、
耐食性を大幅に向上させる表面処理方法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides an electrolytic treatment of stainless steel to reduce surface gloss,
The present invention relates to a surface treatment method that significantly improves corrosion resistance.
【０００２】[0002]
【従来の技術】フェライト系ステンレス鋼板ＢＡ材を硝
酸水溶液中で電解処理することによって、耐食性が改善
されることが例えば、特開昭５９−６３９８号公報、特
公昭６１−２７６０号公報に開示されている。また、ス
テンレス鋼の高耐食性化を目的として、リン酸、クロム
酸、酸化マグネシウム、ケイ酸ナトリウムを含有する溶
液で、陰極電解処理後、リン酸、モリブデン酸塩を含有
する溶液で、陰極電解処理を行う方法が、特公昭５９−
１２７５５号公報に開示されている。また、従来この他
の表面処理方法として、クロムめっき法がある。この方
法は、ステンレス鋼の表面に金属クロムを電析させるこ
とにより、耐食性を向上させる方法である。2. Description of the Related Art It is disclosed in JP-A-59-6398 and JP-B-61-2760 that the corrosion resistance is improved by electrolytically treating a BA material of a ferritic stainless steel plate in an aqueous nitric acid solution. ing. Further, for the purpose of improving the corrosion resistance of stainless steel, a solution containing phosphoric acid, chromic acid, magnesium oxide, sodium silicate, after cathodic electrolytic treatment, with a solution containing phosphoric acid, molybdate, cathodic electrolytic treatment The method of performing is
It is disclosed in Japanese Patent No. 12755. Further, as another conventional surface treatment method, there is a chromium plating method. This method is a method of improving corrosion resistance by depositing metallic chromium on the surface of stainless steel.
【０００３】これらの方法の内、硝酸水溶液での電解処
理方法は、ある程度の耐食性の向上効果は得られるもの
の、大幅な耐食性向上効果は期待できない。また、特公
昭５９−１２７５５号公報に開示される方法は耐食性が
充分とは言えないことと、処理溶液組成が複雑な上、二
つの処理溶液を用いるので生産性も劣る。またクロムめ
っき法は、耐食性向上効果は得られるものの、消費電力
が多く、処理コストも高く生産性が劣るという問題点を
有する。Among these methods, the electrolytic treatment method using a nitric acid aqueous solution can obtain a certain degree of improvement in corrosion resistance, but cannot expect a significant improvement in corrosion resistance. Further, the method disclosed in Japanese Patent Publication No. 59-12755 is not sufficient in corrosion resistance, the treatment solution composition is complicated, and two treatment solutions are used, so that the productivity is inferior. Further, the chrome plating method has a problem in that although the corrosion resistance improving effect is obtained, the power consumption is high, the processing cost is high, and the productivity is poor.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、上記従来技
術の問題点に鑑みてなされたもので、ステンレス鋼の表
面光沢を殆ど損なうことなく大幅に耐食性を向上させる
表面処理方法を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides a surface treatment method capable of significantly improving the corrosion resistance of a stainless steel without substantially impairing the surface gloss. With the goal.
【０００５】[0005]
【課題を解決するための手段】本発明者は、ステンレス
鋼を更に高耐食性化するための表面処理について、種々
の研究を重ねた結果、硝酸ナトリウムとモリブデン酸ア
ンモニウムから成る水溶液で第１処理として低電気量で
陽極電解処理を行った後、第２処理として陰極電解処理
を行うことにより、ステンレス鋼の表面光沢を殆ど損な
うことなく、耐食性が大幅に向上するという知見を得
た。耐食性向上効果の機構の詳細については、不明であ
るが、硝酸イオンによる、クロムを主体とする不働態皮
膜強化と金属モリブデンの電着の作用と推定される。ま
た、金属モリブデンを電着するための、電解処理溶液と
しては、硝酸とモリブデン酸アンモニウムから成る水溶
液でも可能であるが、中性塩である硝酸ナトリウムとモ
リブデン酸アンモニウムから成る水溶液の方が、刺激臭
の発生が殆どない上、耐食性向上効果も良好であること
を知見した。また、金属モリブデンを電着するために
は、モリブデン酸ナトリウムでも可能であるが、水への
溶け易さ、及びコスト、耐食性向上効果の点から、モリ
ブデン酸アンモニウムが有利であることも知見した。The present inventor has conducted various studies on the surface treatment for further improving the corrosion resistance of stainless steel. As a result, the first treatment with an aqueous solution of sodium nitrate and ammonium molybdate is conducted. It was found that by performing the anodic electrolysis treatment with a low electricity amount and then performing the cathodic electrolysis treatment as the second treatment, the corrosion resistance is significantly improved with almost no loss of the surface gloss of the stainless steel. Although the details of the mechanism of the corrosion resistance improving effect are not clear, it is presumed that the action of strengthening the passive film mainly composed of chromium and electrodeposition of molybdenum metal by nitrate ions. An electrolytic treatment solution for electrodepositing metallic molybdenum can be an aqueous solution of nitric acid and ammonium molybdate, but an aqueous solution of neutral salts of sodium nitrate and ammonium molybdate is more effective. It was found that almost no odor was generated and the effect of improving the corrosion resistance was good. It was also found that sodium molybdate can be used for electrodeposition of metallic molybdenum, but ammonium molybdate is advantageous from the viewpoints of solubility in water, cost, and effect of improving corrosion resistance.
【０００６】即ち、このような知見に基づく本発明は、
第１処理として、硝酸ナトリウム５０〜２５０ｇ／リッ
トル、モリブデン酸アンモニウム５０〜２５０ｇ／リッ
トルを含有する水溶液で、電気量１０〜５０クーロン／
ｄｍ2 の陽極電解処理を行った後、第２処理として、前
記水溶液で電気量５０〜３００クーロン／ｄｍ2 の陰極
電解処理を行うことを特徴とするステンレス鋼の表面処
理方法である。That is, the present invention based on such knowledge is
As the first treatment, an aqueous solution containing 50 to 250 g / liter of sodium nitrate and 50 to 250 g / liter of ammonium molybdate, and an electric quantity of 10 to 50 coulomb /
After the anodic electrolysis treatment dm 2, as the second process is a surface treatment method for a stainless steel which is characterized in that the cathodic electrolytic treatment of electrically amount 50-300 coulomb A / dm 2 at the solution.
【０００７】以下、本発明法について詳細に説明する。
本発明で処理する材料は、ステンレス鋼であれば良い
が、ＳＵＳ３０４、ＳＵＳ４３０等の比較的耐食性の低
い汎用鋼への適用が効果的である。次に、本発明条件の
限定理由について説明する。The method of the present invention will be described in detail below.
The material to be treated in the present invention may be stainless steel, but it is effective to apply it to general-purpose steel having relatively low corrosion resistance such as SUS304 and SUS430. Next, the reasons for limiting the conditions of the present invention will be described.
【０００８】図１に耐銹性と硝酸ナトリウムとモリブデ
ン酸アンモニウム濃度の関係を示す。図には、発銹なし
を○、僅かに発銹が△、発銹があるものを×とした。供
試材としては、ＳＵＳ３０４，２Ｂ材を用い、電解電気
量として、第１処理では、１０クーロン／ｄｍ2 で陽極
電解処理を行い、第２処理では、５０クーロン／ｄ
ｍ2 、溶液温度５０℃として、硝酸ナトリウム濃度とモ
リブデン酸アンモニウム濃度を変えて処理した材料に耐
銹性試験（塩水噴霧）として、８時間噴霧−１６時間休
止を１０回繰り返し、その他の条件は、ＪＩＳ（Ｚ２３
７１）に準拠して行った。FIG. 1 shows the relationship between rust resistance and the concentrations of sodium nitrate and ammonium molybdate. In the figure, no rusting is indicated by ○, slightly rusting is indicated by △, and rusting is indicated by ×. As the test material, SUS304, 2B material was used, and in the first treatment, an anodic electrolysis treatment was performed at 10 coulomb / dm 2 , and in the second treatment, 50 coulomb / d.
m 2 at a solution temperature of 50 ° C., the material treated by changing the sodium nitrate concentration and the ammonium molybdate concentration was subjected to a rust resistance test (salt water spray) by repeating spraying for 8 hours and resting for 16 hours 10 times. , JIS (Z23
71).
【０００９】図１より、本発明の電解処理する水溶液の
硝酸ナトリウム濃度は、５０〜２５０ｇ／リットルが良
好である。即ち、５０ｇ／リットル未満では、耐食性向
上に充分な表面皮膜を形成せず、また、２５０ｇ／リッ
トルを超えると耐食性向上効果が飽和すると共に、硝酸
ナトリウムの持ち出し量も多くなり、経済的でない。硝
酸ナトリウムの望ましい範囲は、１００〜２００ｇ／リ
ットルである。また、モリブデン酸アンモニウムの濃度
も、５０〜２５０ｇ／リットルとするのが良い。即ち、
５０ｇ／リットル未満では、充分な防食効果が得られ
ず、２５０ｇ／リットルを超えると耐食性向上効果が飽
和すると共に、モリブデン酸アンモニウムの持ち出し量
も多くなり、経済的でなくなる。望ましい濃度範囲は、
１００〜２００ｇ／リットルである。From FIG. 1, the concentration of sodium nitrate in the aqueous solution for electrolytic treatment of the present invention is preferably 50 to 250 g / liter. That is, if it is less than 50 g / liter, a surface film which is not sufficient for improving the corrosion resistance is not formed, and if it exceeds 250 g / liter, the corrosion resistance improving effect is saturated and the amount of sodium nitrate carried out is large, which is not economical. The preferred range of sodium nitrate is 100-200 g / liter. Also, the concentration of ammonium molybdate is preferably 50 to 250 g / liter. That is,
If it is less than 50 g / liter, a sufficient anticorrosion effect cannot be obtained, and if it exceeds 250 g / liter, the corrosion resistance improving effect is saturated and the amount of ammonium molybdate taken out becomes large, which is not economical. The desired concentration range is
It is 100 to 200 g / liter.
【００１０】図２に耐銹性と電解電気量の関係を示す。
即ち、供試材として、ＳＵＳ３０４，２Ｂ材を用い、処
理溶液として、硝酸ナトリウム：５０ｇ／リットル、モ
リブデン酸アンモニウム：５０ｇ／リットル、溶液温
度：５０℃の条件で、前記の条件で処理した材料を耐銹
性試験（塩水噴霧試験）として、８時間噴霧−１６時間
休止を１０回繰り返し、その他の条件は、ＪＩＳ（Ｚ２
３７１）に準拠して行った結果である。FIG. 2 shows the relationship between rust resistance and the amount of electrolysis.
That is, SUS304, 2B material was used as the test material, and the treatment solution was treated under the above conditions under the conditions of sodium nitrate: 50 g / liter, ammonium molybdate: 50 g / liter, and solution temperature: 50 ° C. As a rust resistance test (salt spray test), spraying for 8 hours and resting for 16 hours were repeated 10 times, and other conditions were JIS (Z2
371).
【００１１】図から明らかなように、上記水溶液中で陽
極電解処理（第１処理）を行う場合の電解電気量は、１
０〜５０クーロン／ｄｍ2 であることが好ましい。その
理由は、１０クーロン／ｄｍ2 未満では、ステンレス鋼
の表面に吸着している汚れを効果的に除去できず、第２
処理における金属モリブデンの電着による防ぐ効果が得
られず、また５０クーロン／ｄｍ2 を超えると、ステン
レス鋼素材の光沢低下を生じるためである。望ましい電
気量の範囲は、３０〜４０クーロン／ｄｍ2 である。As is clear from the figure, the amount of electrolysis when the anodic electrolysis treatment (first treatment) is carried out in the above aqueous solution is 1
It is preferably 0 to 50 coulombs / dm 2 . The reason is that if it is less than 10 coulombs / dm 2 , the dirt adsorbed on the surface of the stainless steel cannot be effectively removed.
This is because the effect of preventing the electrodeposition of metallic molybdenum in the treatment cannot be obtained, and when it exceeds 50 coulomb / dm 2 , the gloss of the stainless steel material is lowered. A desirable range of the amount of electricity is 30 to 40 coulombs / dm 2 .
【００１２】また、図から陽極電解処理後の陰極電解処
理を行う場合の電気量を５０〜３００クーロンにするの
が良い。即ち、このように限定した理由は、５０クーロ
ン／ｄｍ2 未満では、防食効果を有する充分な表面皮膜
を形成せず、３００クーロン／ｄｍ2 を超えると防食効
果が飽和すると共に、変色を生じるからである。From the figure, it is preferable to set the quantity of electricity in the case of performing the cathodic electrolysis after the anodic electrolysis to 50 to 300 coulombs. That is, the reason for limiting in this way is that if it is less than 50 coulombs / dm 2 , a sufficient surface film having an anticorrosion effect is not formed, and if it exceeds 300 coulombs / dm 2 , the anticorrosion effect is saturated and discoloration occurs. Is.
【００１３】陽極電解処理を行った後、陰極電解処理を
行う理由は、ステンレス鋼素材の表面を極く僅かに溶解
し、表面に吸着している汚れを効果的に除去し、陰極電
解処理による金属モリブデンの電着を均一化するためで
ある。また、本発明の電解処理溶液の温度は、常温程度
で充分であるが、４０〜６０℃の温度にすればなお好ま
しい。The reason why the cathodic electrolysis is performed after the anodic electrolysis is that the surface of the stainless steel material is slightly dissolved and the dirt adsorbed on the surface is effectively removed. This is to make the electrodeposition of molybdenum metal uniform. In addition, the temperature of the electrolytic treatment solution of the present invention is about room temperature, but a temperature of 40 to 60 ° C. is more preferable.
【００１４】[0014]
【実施例】以下に、本発明の実施例を示す。代表的なオ
ーステナイト系ステンレス鋼であるＳＵＳ３０４の１mm
厚の２Ｂ製品ステンレス鋼板を被処理材として用いた。
本発明例及び比較例で得られた材料の製品特性を表１−
１、表１−２に示す。なお、処理溶液の温度は５０℃一
定で行った。EXAMPLES Examples of the present invention will be shown below. 1mm of SUS304 which is a typical austenitic stainless steel
A thick 2B product stainless steel plate was used as the material to be treated.
The product properties of the materials obtained in the examples of the present invention and the comparative examples are shown in Table 1-
1, shown in Table 1-2. The temperature of the treatment solution was constant at 50 ° C.
【００１５】表１の製品特性の評価方法および評価基準
は以下に示す方法による。 （イ）孔食電位測定試験 ＪＩＳ（Ｇ０５７７）法で規定される孔食電位測定法に
より試験を行った。測定電位（ｍＶ、ｖｓ ＳＣＥ）を
記載した。 （ロ）塩水噴霧試験 ８時間噴霧１６時間休止の繰り返しを１０回行った。そ
の他の方法はＪＩＳ（Ｚ２３７１）法に準拠した。 評価：○は発銹なし △は僅かに発銹 ×は激しく発銹The evaluation methods and evaluation criteria of the product characteristics in Table 1 are based on the following methods. (A) Pitting corrosion potential measurement test The test was performed by the pitting corrosion potential measurement method specified by JIS (G0577) method. The measured potential (mV, vs SCE) is described. (B) Salt spray test The spraying for 8 hours and the rest for 16 hours were repeated 10 times. Other methods were based on JIS (Z2371) method. Rating: ○: No rusting △: Slight rusting ×: Severe rusting
【００１６】（ハ）表面光沢 表面処理後の鋼板の表面反射率により評価した。表面反
射率は、タングステンランプを光源とする直径１mmの光
束を入射角４５度で試料面に照射し、その正反射光の強
度を銀蒸着の場合を１００％として、表示したものであ
る。上記表面反射率と光沢ランクの関係は表２のとおり
である。 （ニ）色調 表面処理前後のステンレス鋼板表面を外観で評価した。 ○は変化なし ×は黄色に変化を示す(C) Surface Gloss The surface reflectance of the steel sheet after the surface treatment was evaluated. The surface reflectance is indicated by irradiating a sample surface with a light beam having a diameter of 1 mm using a tungsten lamp as a light source at an incident angle of 45 degrees and setting the intensity of the regular reflection light to 100% in the case of silver vapor deposition. Table 2 shows the relationship between the surface reflectance and the gloss rank. (D) Color tone The surface of the stainless steel plate before and after the surface treatment was visually evaluated. ○ indicates no change × indicates yellow change
【００１７】[0017]
【表１】 [Table 1]
【００１８】[0018]
【表２】 [Table 2]
【００１９】[0019]
【表３】 [Table 3]
【００２０】本発明法で電解処理したステンレス鋼板
は、耐食性（孔食電位測定結果、塩水噴霧試験結果）お
よび表面光沢に優れ、色調も変化しないことが判る。一
方、比較例の電解処理方法では、耐食性あるいは表面光
沢、色調または経済性のいずれかが劣っている。It can be seen that the stainless steel sheet electrolytically treated by the method of the present invention is excellent in corrosion resistance (pitching corrosion potential measurement result, salt spray test result) and surface gloss, and does not change in color tone. On the other hand, the electrolytic treatment method of Comparative Example is inferior in corrosion resistance, surface gloss, color tone or economy.
【００２１】[0021]
【発明の効果】以上の如く、本発明法によれば、ステン
レス鋼板を電気化学的な表面処理を行うことにより、表
面光沢、色調を損なうことなく、耐食性が大幅に向上し
たステンレス鋼板を効率的に製造することができるの
で、工業的効果は大きい。As described above, according to the method of the present invention, a stainless steel sheet having a significantly improved corrosion resistance can be efficiently produced by electrochemically treating the stainless steel sheet without impairing the surface gloss and color tone. Since it can be manufactured in a large amount, it has a great industrial effect.
【図１】耐銹性と硝酸ナトリウム、モリブデン酸アンモ
ニウム濃度の関係を示す図である。FIG. 1 is a diagram showing a relationship between rust resistance and sodium nitrate and ammonium molybdate concentrations.
【図２】耐銹性と電解電気量の関係を示す図である。FIG. 2 is a diagram showing the relationship between rust resistance and the amount of electrolysis electricity.
Claims (1)
２５０ｇ／リットル、モリブデン酸アンモニウム５０〜
２５０ｇ／リットルを含む水溶液で、電気量１０〜５０
クーロン／ｄｍ2 の陽極電解処理を行った後、第２処理
として、前記水溶液で５０〜３００クーロン／ｄｍ2 の
陰極電解処理を行うことを特徴とするステンレス鋼の表
面処理方法。1. As the first treatment, sodium nitrate 50 to 50
250 g / liter, ammonium molybdate 50-
Aqueous solution containing 250 g / l, electricity quantity 10-50
After the anodic electrolysis treatment coulomb / dm 2, as the second process, the surface treatment method of the stainless steel which is characterized in that the cathodic electrolytic treatment of 50 to 300 coulombs A / dm 2 at the solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32444994A JPH08176891A (en) | 1994-12-27 | 1994-12-27 | Surface treatment of stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32444994A JPH08176891A (en) | 1994-12-27 | 1994-12-27 | Surface treatment of stainless steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH08176891A true JPH08176891A (en) | 1996-07-09 |
Family
ID=18165940
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32444994A Withdrawn JPH08176891A (en) | 1994-12-27 | 1994-12-27 | Surface treatment of stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH08176891A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2319529A (en) * | 1996-11-26 | 1998-05-27 | Fujimi Inc | Rinsing composition |
| SG93296A1 (en) * | 2000-12-19 | 2002-12-17 | United Technologies Corp | Compound, non-chromium conversion coatings for aluminum alloys |
-
1994
- 1994-12-27 JP JP32444994A patent/JPH08176891A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2319529A (en) * | 1996-11-26 | 1998-05-27 | Fujimi Inc | Rinsing composition |
| GB2319529B (en) * | 1996-11-26 | 1999-02-17 | Fujimi Inc | Rinsing method and composition |
| US6022837A (en) * | 1996-11-26 | 2000-02-08 | Fujimi Incorporated | Method for rinsing a polished memory hard disk |
| SG93296A1 (en) * | 2000-12-19 | 2002-12-17 | United Technologies Corp | Compound, non-chromium conversion coatings for aluminum alloys |
| US6613390B2 (en) | 2000-12-19 | 2003-09-02 | United Technologies Corporation | Compound, non-chromium conversion coatings for aluminum alloys |
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