WO2014103703A1 - Passivation method for stainless steel - Google Patents

Passivation method for stainless steel Download PDF

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WO2014103703A1
WO2014103703A1 PCT/JP2013/083095 JP2013083095W WO2014103703A1 WO 2014103703 A1 WO2014103703 A1 WO 2014103703A1 JP 2013083095 W JP2013083095 W JP 2013083095W WO 2014103703 A1 WO2014103703 A1 WO 2014103703A1
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hydrogen peroxide
weight
concentration
stainless steel
immersion
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PCT/JP2013/083095
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French (fr)
Japanese (ja)
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義明 井田
文幸 津高
克久 杉本
清隆 石見
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マルイ鍍金工業株式会社
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Priority to JP2014554297A priority Critical patent/JPWO2014103703A1/en
Publication of WO2014103703A1 publication Critical patent/WO2014103703A1/en

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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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/78—Pretreatment of the material to be coated
    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F17/00—Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/16—Polishing
    • C25F3/22—Polishing of heavy metals
    • C25F3/24—Polishing of heavy metals of iron or steel

Definitions

  • the present invention relates to a method for passivating stainless steel, and sometimes relates to a method for passivating stainless steel in consideration of the environment.
  • the methods for passivating stainless steel are roughly divided into the following three methods.
  • a method of immersing in a solution containing a strong oxidizing agent is generally used, and nitric hydrofluoric acid (about 1 wt% HF, 30 wt% HNO 3 , remaining H 2 O), or 10 to Stainless steel is immersed in a highly oxidizing solution such as 30% by weight of nitric acid, or electrolytic treatment is performed together with the immersion.
  • JP-A-52-106333 a method of using a mixed solution of nitric acid and hydrochloric acid as a highly oxidative solution is disclosed in JP-A-52-106333.
  • a solution containing 5 to 40% by weight of nitric acid and 0.5 to 2.0% by weight of hydrochloric acid, and the remaining water and inhibitor 0.1 g to 10 g / l is heated to 50 to 70 ° C. for 30 to 90 seconds.
  • the steel is immersed.
  • Japanese Patent Application Laid-Open No. 2001-115271 discloses a method of using hydrogen peroxide having a low environmental load in the passivating step.
  • Japanese Patent Application Laid-Open No. 11-293482 discloses a technique in which hydrogen peroxide and another acidic solution are mixed and used for the passivation treatment.
  • the thickness is essentially 10 to 30 mm as represented by Cr 2 O 3 ⁇ nH 2 O. It is believed to be a uniform and thin chemically stable amorphous oxide film. Passivation treatment in nitric hydrofluoric acid or nitric acid is considered to form a stable passive film by concentrating Cr elements in the passive film.
  • JP-A-52-106333 JP 2001-115271 A Japanese Patent Laid-Open No. 11-293482
  • hydrofluoric acid is designated as a Class 2 material such as the Industrial Safety and Health Act Construction Order Specified Chemical Substances, and nitrogen oxides are generated in mixtures with sulfuric acid Therefore, development of a process not using these has been desired.
  • nitric acid when used, it is necessary to neutralize the used nitric acid with caustic soda and discard it, and it is desirable to omit this step.
  • the passivation film is evaluated by considering the process of the passivation treatment itself as well as the fact that the treatment at the previous stage of the passivation treatment has a great influence on the characteristics of the passivation film. When doing this, it is necessary to focus not only on each part of the passivating process but on all the steps.
  • the present invention has been proposed in view of the above-described conventional circumstances, and provides a passivation treatment for stainless steel that does not use a strongly acidic solution that requires post-treatment during the passivation treatment.
  • an object to be treated is first electropolished in a mixed solution of sulfuric acid and phosphoric acid, and then immersed in hydrogen peroxide.
  • the formed passive film can form a film of the same quality as that obtained by passivating with a nitric acid solution at a pitting potential, which is an index of chloride pitting resistance.
  • a pitting potential which is an index of chloride pitting resistance.
  • FIG. 1 is a diagram showing the pitting potential when hydrogen peroxide is used for passivation after each polishing.
  • FIG. 2 is a diagram showing the pitting corrosion potential when the immersion time in hydrogen peroxide is changed.
  • FIG. 3 is a diagram showing the pitting potential when the hydrogen peroxide bath temperature is changed.
  • FIG. 4 is a diagram showing the pitting corrosion potential when the bath concentration of hydrogen peroxide is changed.
  • FIG. 5 is a diagram showing the pitting potential when the NaCl concentration used when measuring the pitting potential is changed.
  • FIG. 6 is a diagram showing the pitting potential when the NaCl immersion days used when measuring the pitting potential are changed.
  • FIG. 7 is a view showing a comparison between the present invention and polishing with citric acid and hydrogen peroxide treatment.
  • FIG. 8 is a diagram showing the results of surface analysis of a sample by the method of the present application and a conventional method.
  • the surface of the stainless steel is passivated by electropolishing the stainless steel to be treated and then immersing it in hydrogen peroxide.
  • the electropolishing is performed in a mixed solution of sulfuric acid and phosphoric acid using the object to be treated as the positive electrode.
  • the mixed solution when 85 wt% phosphoric acid and 98 wt% sulfuric acid are used, the ratio of phosphoric acid to sulfuric acid is 50 to 90%: 10 to 50% (volume%), and the temperature is 30 to 80 ° C.
  • the current is 1 to 20 A / dm 2 and the time is 30 seconds to 60 minutes.
  • the immersion in the hydrogen peroxide is a hydrogen peroxide concentration of 1% by weight or more, a temperature of 10 ° C. or more, and an immersion time of 30 minutes or more.
  • the gloss is lowered when the concentration of phosphoric acid is less than 50%, and the cost is increased when the concentration is more than 90%.
  • the electrolytic treatment is performed at a current density of 1 to 20 A / dm 2 at a temperature of 30 to 80 ° C. for a time of 30 seconds to 60 minutes. If the temperature is lower than 30 ° C., the dissolution rate of iron is not sufficient, and the surface of the object to be treated cannot be made sufficiently rich in chromium. On the other hand, if the temperature is higher than 80 ° C., the odor of sulfuric acid is trapped in the atmosphere, causing a problem in workability. If the current density is less than 1 A / dm 2 , the elution of iron is not sufficient, and if it is greater than 20 A / dm 2 , the uniformity of the current density is lowered, leading to quality deterioration.
  • the relationship between the temperature, current density, and electrolytic treatment time is relatively determined so that the amount of iron elution does not become too large, and is too small so as not to hinder the subsequent electroless treatment. .
  • the concentration and temperature of hydrogen peroxide used for the above electroless treatment, and the immersion time are relatively determined within the following range in order to form a more passive characteristic.
  • the concentration of hydrogen peroxide is 1% by weight or more. If it is lower than 1% by weight, the oxidation effect is not sufficient, and a passive film excellent in corrosion resistance or pitting potential cannot be formed.
  • the upper limit of the concentration of hydrogen peroxide is not limited, but if it exceeds 15% by weight, it can be said that the film quality is sufficient, but there is a need for waste water treatment after work, and there is a problem in cost.
  • the immersion treatment time in hydrogen peroxide is 30 minutes or more even if the concentration of hydrogen peroxide is 1% by weight, which is the lowest. If it is shorter than 30 minutes, an excellent passive film is not formed. Although there is no upper limit of the immersion time, for example, when it is a long time such as 5 hours, an obstacle in terms of workability and cost occurs.
  • FIG. 1 shows an experiment demonstrating that electropolishing is effective as a pretreatment for passivating stainless steel.
  • Stainless steel (SUS304) was buffed (No. 400) and then immersed in 3.5% by weight of hydrogen peroxide at 25 ° C. for 2 hours to passivate sample 1, emery paper (No. 600) and each sample 2 immersed in 3.5 wt% hydrogen peroxide at 25 ° C. for 2 hours has a pitting potential of around 0 mV.
  • the present invention can use hydrogen peroxide, which is not regulated for disposal at a low concentration (3.5% by weight here).
  • the pitting corrosion potential is measured with a 3.5 wt% NaCl solution at a temperature of 25 ° C.
  • Example 2 (Immersion time) Next, the stainless steel material was buffed (No. 400), electropolished under the same conditions as in Example 1 above, and then heated to 3.5 wt% hydrogen peroxide at 25 ° C. for 30 minutes, 1 hour, 2 hours.
  • FIG. 2 shows the results (measured median value of the five samples) of the pitting corrosion potential measured for five samples each time when they were passivated by immersion for a period of time.
  • Some samples showed a pitting potential of 1000 mV or less in 30 minutes and 1 hour, but at least 900 mV, and in addition, the median is 1000 mV or more as shown in FIG. It can be said that it is a value to obtain. When immersed for 2 hours, all samples are 1000 mV or more.
  • the pitting potential is 150 mV or less, and it can be understood that a passive film having good corrosion resistance cannot be formed only by electropolishing.
  • Example 3> (Bath temperature) The stainless steel material was buffed (No. 400), electropolished under the same conditions as in Example 1, and then immersed in 3.5% by weight of hydrogen peroxide for 2 hours, and the bath temperature was 5 ° C. Results of measuring the pitting potential when immersed in 3.5 wt% NaCl for samples passivated at 10 ° C, 15 ° C, 25 ° C, and 40 ° C (each 5 temperatures) (center of 5 samples) Value) is shown in FIG.
  • the pitting corrosion potential When the temperature is 5 ° C. or less (including 5 ° C.), the pitting corrosion potential is 500 mV or less in more than half of the sample, and even if the median is taken, it can be understood that a sufficiently strong passive film is not formed. .
  • the median value of the pitting corrosion potential is around 1000 mV, and it can be understood that it is a value that can withstand practical use.
  • all samples At 25 ° C and 40 ° C, all samples have a pitting corrosion potential of 1000 mV or more. .
  • Example 4 (Bath concentration) After buffing the stainless steel material (No. 400) and electrolytic polishing under the same conditions as in Example 1, the immersion temperature of hydrogen peroxide was fixed at 25 ° C and the immersion time was fixed at 2 hours, and the bath concentration was changed.
  • FIG. 4 shows an embodiment in the case of such a case.
  • Fig. 4 shows the results of measuring the pitting corrosion potential (median value of 5 samples) by immersing 5 samples of each concentration in hydrogen peroxide with the following concentrations (1) to (9). It is shown.
  • a pitting corrosion potential with a median value of 800 mV or more was observed even when the concentration of hydrogen peroxide was less than 1% by weight (0.98% by weight), and it can be said that a moderate passive film was formed. From 1 wt% to 3 wt% (eg, 1.75 wt%), depending on the sample, a pitting corrosion potential of 1000 mV or less was also observed, but the median value is 1000 mV or more, and it can be said that it is a passivated membrane that can withstand practical use. When the concentration of hydrogen peroxide exceeds 3% by weight (for example, 3.5% by weight), any sample can obtain a pitting potential of 1000 mV or more.
  • FIG. 5 shows the measurement results of pitting corrosion potential when the concentration of NaCl as a test solution for pitting corrosion potential was changed.
  • a sample (FIG. 5 (a)) in which the electropolished sample was passivated by immersion in a 30 wt% nitric acid solution at 25 ° C. for 2 hours was also used.
  • the sample according to the present invention maintains a pitting corrosion potential of 1000 mV or more even when the NaCl concentration reaches 25% by weight or the saturation concentration.
  • Example 6 NaCl immersion time
  • the pitting potential was measured after being immersed in a 3.5 wt% NaCl solution for 1 to 100 days before the pitting potential measurement. .
  • the concentration of NaCl as a test solution for pitting potential after immersion was fixed at 3.5%.
  • the measurement result of the pitting corrosion potential when the immersion days are changed is shown in FIG.
  • FIG. 7 shows a confirmation experiment on the item related to the present invention, the point of passivation with hydrogen peroxide after polishing with an organic acid.
  • a buffed stainless steel material was dipped in 20% by weight, 45 ° C. citric acid for 30 minutes to polish the surface, and further immersed in 4.0% by weight, 45 ° C. hydrogen peroxide for 1 hour, Example 1
  • the sample was electropolished under the same conditions as above and immersed in 3.5 wt% hydrogen peroxide at 25 ° C. for 2 hours, and compared with the pitting potential when anodically polarized in a 3.5 wt% NaCl solution.
  • the sample treated with citric acid had a pitting corrosion potential of 300 mV at most, whereas the sample according to the present invention showed a pitting corrosion potential of 1000 mV or more.
  • FIG. 8 shows a conventional method (immersion in 30% nitric acid after electropolishing for 2 hours at a temperature of 25 ° C.) and a method according to the present invention (immersion in 3.5% hydrogen peroxide after electropolishing for 2 hours at a temperature of 25 ° C.).
  • 2 shows the result of XPS analysis of a sample that has been subjected to the above treatment.
  • the sample by the conventional method shows an increase in the iron content (decrease in the chromium content) in the sputtering time of about 0.3 minutes, whereas the method of the present application shows the same phenomenon from about 0.5 minutes. That is, it can be understood that the chromium-rich layer is thick and the passive film to be formed is thick.
  • the present invention can use hydrogen peroxide that does not require pretreatment for disposal in the passivating process, and therefore has great advantages from the environmental and cost viewpoints, and the industrial applicability is extremely large. .

Abstract

Provided is a passivation method for stainless steel having a low environmental impact and superior characteristics. Material to be processed that has undergone electropolishing is immersed in hydrogen peroxide. In this immersion in the hydrogen peroxide, a hydrogen peroxide concentration is 1% by weight, temperature 10°C or greater, and immersion time 30 minutes or more. In addition, the electrolyte used in the electropolishing is a liquid mixture of sulfuric acid and phosphoric acid, and when the liquid mixture uses 85% phosphoric acid and 98% sulfuric acid, the ratio of phosphoric acid and sulfuric acid is 50 - 90%:10 - 50% (percent by volume), temperature 30 - 80°C, current 1 - 20 A/dm2, and time 30 seconds - 60 minutes.

Description

ステンレス鋼の不動態化方法Methods for passivating stainless steel
　本発明は、ステンレス鋼の不動態化方法に関し、時に環境を考慮したステンレス鋼の不動態化方法に関するものである。 The present invention relates to a method for passivating stainless steel, and sometimes relates to a method for passivating stainless steel in consideration of the environment.
　ステンレス鋼の不動態化方法は、大きく分けて以下の３つの方法がある。
（１）硝酸その他の強力な酸化剤を含む溶液に浸漬する方法。
（２）酸素または、清浄な空気中における低温加熱による方法。
（３）酸化剤を含む溶液中における陽極分極による方法。 The methods for passivating stainless steel are roughly divided into the following three methods.
(1) A method of immersing in a solution containing nitric acid or other strong oxidizing agent.
(2) A method by low temperature heating in oxygen or clean air.
(3) A method by anodic polarization in a solution containing an oxidizing agent.
　このうち、（１）の「強力な酸化剤を含む溶液に浸漬する方法」が一般的で、硝弗酸（約１重量％HF、３０重量％HNO3、残りH2O）、あるいは１０～３０重量％の硝酸などの酸化性の強い溶液にステンレス鋼を浸漬し、あるいは浸漬とともに電解処理するようにしている。 Of these, (1) “a method of immersing in a solution containing a strong oxidizing agent” is generally used, and nitric hydrofluoric acid (about 1 wt% HF, 30 wt% HNO 3 , remaining H 2 O), or 10 to Stainless steel is immersed in a highly oxidizing solution such as 30% by weight of nitric acid, or electrolytic treatment is performed together with the immersion.
　また、酸化性の強い溶液として、硝酸と塩酸の混合液を使用する方法が、特開昭５２－１０６３３３号公報に開示されている。硝酸を５～４０重量％、塩酸を０．５～２．０重量％含み、残り水およびインヒビタ０．１ｇ～１０ｇ／ｌよりなる溶液を、５０～７０℃に加熱して３０～９０秒ステンレス鋼を浸漬するようにしたものである。 Further, a method of using a mixed solution of nitric acid and hydrochloric acid as a highly oxidative solution is disclosed in JP-A-52-106333. A solution containing 5 to 40% by weight of nitric acid and 0.5 to 2.0% by weight of hydrochloric acid, and the remaining water and inhibitor 0.1 g to 10 g / l is heated to 50 to 70 ° C. for 30 to 90 seconds. The steel is immersed.
　上記硝弗酸や硝酸に代えて、過酸化水素を使用する不動態化方法が提案されている。例えば、特開２００１－１１５２７１号公報には、不動態化の工程で環境負荷の小さい過酸化水素を使用する方法が開示されている。また、特開平１１－２９３４８２号公報には、不動態化処理に過酸化水素と他の酸性溶液を混合して使用する技術が開示されている。 A passivating method using hydrogen peroxide instead of the above nitric hydrofluoric acid or nitric acid has been proposed. For example, Japanese Patent Application Laid-Open No. 2001-115271 discloses a method of using hydrogen peroxide having a low environmental load in the passivating step. Japanese Patent Application Laid-Open No. 11-293482 discloses a technique in which hydrogen peroxide and another acidic solution are mixed and used for the passivation treatment.
　ステンレス鋼表面に形成される不動態皮膜の構造はまだ充分には解明されていないが、本質的には、Cr2O3・nH2Oで表されるような、厚さが１０～３０Åの均一で薄い化学的に安定な非晶質の酸化膜になっていると考えられている。硝弗酸や硝酸中での不動態化処理は、不動態皮膜中のCr元素の濃縮により、安定な不動態皮膜を形成させると考えられている。 Although the structure of the passive film formed on the stainless steel surface has not been fully elucidated, the thickness is essentially 10 to 30 mm as represented by Cr 2 O 3 · nH 2 O. It is believed to be a uniform and thin chemically stable amorphous oxide film. Passivation treatment in nitric hydrofluoric acid or nitric acid is considered to form a stable passive film by concentrating Cr elements in the passive film.
特開昭５２－１０６３３３号公報JP-A-52-106333 特開２００１－１１５２７１号公報JP 2001-115271 A 特開平１１－２９３４８２号公報Japanese Patent Laid-Open No. 11-293482
　これらの不動態化処理のうち弗化水素酸（ＨＦ）は労働安全衛生法施工令特定化学物質等第２種物質に指定されていること、および、硫酸との混合物においては窒素酸化物が発生するため、これらを用いない工程の開発が望まれていた。 Of these passivation treatments, hydrofluoric acid (HF) is designated as a Class 2 material such as the Industrial Safety and Health Act Construction Order Specified Chemical Substances, and nitrogen oxides are generated in mixtures with sulfuric acid Therefore, development of a process not using these has been desired.
　更に、硝酸を使用した場合には、使用後の硝酸は苛性ソーダで中和してから廃棄する必要があり、この工程も省略することが望まれる。 Furthermore, when nitric acid is used, it is necessary to neutralize the used nitric acid with caustic soda and discard it, and it is desirable to omit this step.
　特開２００１－１１５２７１号公報に開示された方法では、被加工物を有機酸で研磨した後、硝酸又は過酸化酸水素を含む酸化性溶剤の液に浸漬して不動態化するようになっている。ここで、硝酸を使用する場合は硝酸処理の問題が依然としてのこることになる。また、研磨処理として有機酸を使用しているが、出願人がクエン酸を用いて研磨したステンレス鋼試料に対する過酸化水素の不動態化処理について検討した結果は、満足できるものではなかった（後述の比較例参照）。有機酸での研磨効果は弱いためと考えられる。 In the method disclosed in Japanese Patent Application Laid-Open No. 2001-115271, after a workpiece is polished with an organic acid, the workpiece is passivated by dipping in an oxidizing solvent containing nitric acid or hydrogen peroxide. Yes. Here, when nitric acid is used, the problem of nitric acid treatment still remains. Moreover, although organic acid is used as the polishing treatment, the results of the examination of the passivation treatment of hydrogen peroxide on the stainless steel sample polished by the applicant using citric acid were not satisfactory (described later). See comparative example). This is probably because the polishing effect with organic acids is weak.
　上記、特開平１１－２９３４８２号公報に開示されている方法では、過酸化水素以外の酸性溶液をも使用することになり、後の処理に時間と費用を要するという欠点がある。 In the method disclosed in JP-A-11-293482, an acidic solution other than hydrogen peroxide is also used, and there is a drawback that time and cost are required for subsequent processing.
　加えて、不動態皮膜は、不動態化処理そのものの方法はもちろん、不動態化処理の前段階での処理が不動態皮膜の特性に大きな影響を及ぼす点を考慮すると、不動態化処理を評価するとき、不動態化処理の各部にのみ注目するのではなく、全工程に注目する必要がある。 In addition, the passivation film is evaluated by considering the process of the passivation treatment itself as well as the fact that the treatment at the previous stage of the passivation treatment has a great influence on the characteristics of the passivation film. When doing this, it is necessary to focus not only on each part of the passivating process but on all the steps.
　本発明は上記従来の事情に鑑みて提案されたものであって、不動態化処理時に後処理の必要な強酸性の溶液を用いないステンレス鋼の不動態化処理を提供するものである。 The present invention has been proposed in view of the above-described conventional circumstances, and provides a passivation treatment for stainless steel that does not use a strongly acidic solution that requires post-treatment during the passivation treatment.
　上記目的を達成するために、この発明は、まず、硫酸とリン酸の混合液中で被処理物を電解研磨し、その後過酸化水素に浸漬処理するようになっている。 In order to achieve the above object, according to the present invention, an object to be treated is first electropolished in a mixed solution of sulfuric acid and phosphoric acid, and then immersed in hydrogen peroxide.
　上記の方法を採用することによって、形成された不動態皮膜は耐塩化物孔食性の指標である孔食電位において、従前の硝酸溶液で不動態化した場合と同等の品質の膜を形成することができ、しかも、廃液を下水等に廃棄しても環境に負荷のかからない効果がある。 By adopting the above method, the formed passive film can form a film of the same quality as that obtained by passivating with a nitric acid solution at a pitting potential, which is an index of chloride pitting resistance. In addition, even if the waste liquid is disposed of in sewage or the like, there is an effect that does not impose an environmental burden.
図１は各研磨後の不動態化処理に過酸化水素を使用したときの孔食電位を示す図。FIG. 1 is a diagram showing the pitting potential when hydrogen peroxide is used for passivation after each polishing. 図２は過酸化水素への浸漬時間を変えたときの孔食電位を示す図。FIG. 2 is a diagram showing the pitting corrosion potential when the immersion time in hydrogen peroxide is changed. 図３は過酸化水素の浴温度を変えたときの孔食電位を示す図。FIG. 3 is a diagram showing the pitting potential when the hydrogen peroxide bath temperature is changed. 図４は過酸化水素の浴濃度を変えたときの孔食電位を示す図。FIG. 4 is a diagram showing the pitting corrosion potential when the bath concentration of hydrogen peroxide is changed. 図５は孔食電位の測定時に使用するNaCl濃度を変えたときの孔食電位を示す図。FIG. 5 is a diagram showing the pitting potential when the NaCl concentration used when measuring the pitting potential is changed. 図６は孔食電位の測定時に使用するNaCl浸漬日数を変えたときの孔食電位を示す図。FIG. 6 is a diagram showing the pitting potential when the NaCl immersion days used when measuring the pitting potential are changed. 図７はクエン酸による研磨及び過酸化水素処理と本発明との比較を示す図を示す図。FIG. 7 is a view showing a comparison between the present invention and polishing with citric acid and hydrogen peroxide treatment. 図８は本願の方法と、従来の方法による試料の表面分析の結果を示す図。FIG. 8 is a diagram showing the results of surface analysis of a sample by the method of the present application and a conventional method.
　本発明は被処理物のステンレス鋼を電解研磨し、その後過酸化水素に浸漬することによってステンレス鋼表面を不動態化するようにしている。 In the present invention, the surface of the stainless steel is passivated by electropolishing the stainless steel to be treated and then immersing it in hydrogen peroxide.
　上記電解研磨は、硫酸とリン酸の混合溶液中で、被処理物を正極として行われる。前記混合溶液としては、８５重量％のリン酸と、９８重量%の硫酸を用いた場合リン酸と硫酸の比が、５０～９０％：１０～５０％（容量％）、温度３０～８０℃、電流１～２０Ａ／dm2、時間３０秒～６０分である。 The electropolishing is performed in a mixed solution of sulfuric acid and phosphoric acid using the object to be treated as the positive electrode. As the mixed solution, when 85 wt% phosphoric acid and 98 wt% sulfuric acid are used, the ratio of phosphoric acid to sulfuric acid is 50 to 90%: 10 to 50% (volume%), and the temperature is 30 to 80 ° C. The current is 1 to 20 A / dm 2 and the time is 30 seconds to 60 minutes.
　上記過酸化水素への浸漬は、過酸化水素の濃度１重量％以上、温度１０℃以上であり、浸漬時間は３０分以上である。 The immersion in the hydrogen peroxide is a hydrogen peroxide concentration of 1% by weight or more, a temperature of 10 ° C. or more, and an immersion time of 30 minutes or more.
　上記電解研磨処理において、リン酸の濃度が５０％より小さいと光沢性が低下し、９０%より多いとコスト高となる。 In the above electrolytic polishing treatment, the gloss is lowered when the concentration of phosphoric acid is less than 50%, and the cost is increased when the concentration is more than 90%.
　また、上記電解処理は、温度３０～８０℃の下で、１～２０Ａ／dm2の電流密度で時間３０秒～６０分で行われる。温度が３０℃より低いと鉄分の溶解速度が充分ではなく被処理物の表面を充分にクロムリッチにすることができない。また８０℃より高いと雰囲気に硫酸臭が立ち込め、作業性に問題が生じる。電流密度が１Ａ／dm2より小さいと、鉄分の溶出が充分でなく、また、２０Ａ／dm2より大きいと、電流密度の均一性が低下することで品質の低下を招く。 The electrolytic treatment is performed at a current density of 1 to 20 A / dm 2 at a temperature of 30 to 80 ° C. for a time of 30 seconds to 60 minutes. If the temperature is lower than 30 ° C., the dissolution rate of iron is not sufficient, and the surface of the object to be treated cannot be made sufficiently rich in chromium. On the other hand, if the temperature is higher than 80 ° C., the odor of sulfuric acid is trapped in the atmosphere, causing a problem in workability. If the current density is less than 1 A / dm 2 , the elution of iron is not sufficient, and if it is greater than 20 A / dm 2 , the uniformity of the current density is lowered, leading to quality deterioration.
　上記、温度、電流密度、電解処理時間の関係は、鉄分の溶出量が大きくなり過ぎない程度、また、少なすぎて後の無電解処理に支障を来たさないよう、相対的に決定される。 The relationship between the temperature, current density, and electrolytic treatment time is relatively determined so that the amount of iron elution does not become too large, and is too small so as not to hinder the subsequent electroless treatment. .
　上記無電解処理に使用する過酸化水素の濃度と温度、更に浸漬時間は、より優れた特性の不動態を形成するためには、下記の範囲で相対的に決定される。 The concentration and temperature of hydrogen peroxide used for the above electroless treatment, and the immersion time are relatively determined within the following range in order to form a more passive characteristic.
　すなわち、過酸化水素の濃度は１重量％以上である。１重量％より低いと酸化効果が充分ではなく、耐食性あるいは孔食電位に優れた不動態皮膜を形成することはできない。過酸化水素の濃度の上限は限定されないが、１５重量％より高くなると、膜質は充分といえるが作業後の排水処理の必要性が生じ、コスト面での難点がある。 That is, the concentration of hydrogen peroxide is 1% by weight or more. If it is lower than 1% by weight, the oxidation effect is not sufficient, and a passive film excellent in corrosion resistance or pitting potential cannot be formed. The upper limit of the concentration of hydrogen peroxide is not limited, but if it exceeds 15% by weight, it can be said that the film quality is sufficient, but there is a need for waste water treatment after work, and there is a problem in cost.
　上記過酸化水素への浸漬処理時間は、過酸化水素の濃度が最も低い１重量％であっても３０分以上である。３０分より短いと優れた不動態皮膜を形成するに至らない。浸漬時間の上限はないが、例えば５時間といった長時間になると、作業性、コストの面での障害が生じることになる。 The immersion treatment time in hydrogen peroxide is 30 minutes or more even if the concentration of hydrogen peroxide is 1% by weight, which is the lowest. If it is shorter than 30 minutes, an excellent passive film is not formed. Although there is no upper limit of the immersion time, for example, when it is a long time such as 5 hours, an obstacle in terms of workability and cost occurs.
　＜実施例１＞
　まず、ステンレス鋼を不動態化するについて、その前処理として、電解研磨をすることが有効であることを実証する実験を図１に示す。ステンレス鋼（ＳＵＳ３０４）をバフ研磨（No.400）の後に３．５重量％の過酸化水素に２５℃で２時間浸漬して、不動態化処理した試料１、研磨材としてエメリー紙（No.600）を用い、３．５重量％の過酸化水素に２５℃で２時間浸漬した試料２は、いずれも０mV近辺の孔食電位でしかない。 <Example 1>
First, FIG. 1 shows an experiment demonstrating that electropolishing is effective as a pretreatment for passivating stainless steel. Stainless steel (SUS304) was buffed (No. 400) and then immersed in 3.5% by weight of hydrogen peroxide at 25 ° C. for 2 hours to passivate sample 1, emery paper (No. 600) and each sample 2 immersed in 3.5 wt% hydrogen peroxide at 25 ° C. for 2 hours has a pitting potential of around 0 mV.
　バフ研磨後に、８５重量％のリン酸と、９８重量%の硫酸を用いてリン酸と硫酸の比が、７５％：２５％（容量％）である電解浴で、温度４５℃、電圧８Vで６分間電解研磨した試料３は150ｍV強の孔食電位を示すが、それ以上ではない。 After buffing, an electrolytic bath in which the ratio of phosphoric acid to sulfuric acid is 75%: 25% (volume%) using 85% by weight phosphoric acid and 98% by weight sulfuric acid at a temperature of 45 ° C. and a voltage of 8V. Sample 3 electropolished for 6 minutes shows a pitting potential of over 150 mV but not more.
　バフ研磨後に上記と同じ条件で電解研磨をした後、3.5重量％過酸化水素に２５℃で２時間浸漬して、不動態化処理した試料４は、1000mVを超える孔食電位を示している。 Sample 4 subjected to passivation treatment after electrolytic polishing under the same conditions as above after buffing and then immersed in 3.5 wt% hydrogen peroxide at 25 ° C. for 2 hours shows a pitting corrosion potential exceeding 1000 mV.
　したがって、本願発明は、低い濃度（ここでは3.5重量％）では廃棄に規制の掛からない過酸化水素を使用できることになる。 Therefore, the present invention can use hydrogen peroxide, which is not regulated for disposal at a low concentration (3.5% by weight here).
　尚、上記孔食電位の測定は３．５重量％NaClの溶液で、温度２５℃の下での測定である。 The pitting corrosion potential is measured with a 3.5 wt% NaCl solution at a temperature of 25 ° C.
　＜実施例２＞（浸漬時間）
　次に、ステンレス鋼素材をバフ研磨（No.400）し、上記実施例１と同じ条件で電解研磨した後に、温度25℃の下で3.5重量％の過酸化水素に３０分、１時間、２時間浸漬して不動態化した場合の孔食電位を、各時間５枚の試料について測定した結果（５枚の試料の中央値）を図２に示す。 <Example 2> (Immersion time)
Next, the stainless steel material was buffed (No. 400), electropolished under the same conditions as in Example 1 above, and then heated to 3.5 wt% hydrogen peroxide at 25 ° C. for 30 minutes, 1 hour, 2 hours. FIG. 2 shows the results (measured median value of the five samples) of the pitting corrosion potential measured for five samples each time when they were passivated by immersion for a period of time.
　３０分、１時間では孔食電位が1000mV以下になる試料も見られたが、少なくとも900mVはあり、加えて、中央値としては、図２に示すように、1000mV以上あり、実用には充分耐え得る値であるといえる。２時間の浸漬では全試料が1000mV以上となる。 Some samples showed a pitting potential of 1000 mV or less in 30 minutes and 1 hour, but at least 900 mV, and in addition, the median is 1000 mV or more as shown in FIG. It can be said that it is a value to obtain. When immersed for 2 hours, all samples are 1000 mV or more.
　電解研磨処理の後、過酸化水素に浸漬しない場合は孔食電位が150mV以下となり、電解研磨だけでは耐食性の良い不動態皮膜が形成されないことが理解できる。 After electropolishing, when not immersed in hydrogen peroxide, the pitting potential is 150 mV or less, and it can be understood that a passive film having good corrosion resistance cannot be formed only by electropolishing.
　＜実施例３＞（浴温度）
　上記ステンレス鋼素材をバフ研磨（No.400）し、上記実施例１と同じ条件で電解研磨した後に、3.5重量％の過酸化水素水に２時間浸漬した場合であって、浴温度が５℃、１０℃、１５℃、２５℃、４０℃で不動態化した試料（各温度５枚）について、3.5重量％のNaClに浸漬した場合の孔食電位を測定した結果（５枚の試料の中央値）を図３に示す。 <Example 3> (Bath temperature)
The stainless steel material was buffed (No. 400), electropolished under the same conditions as in Example 1, and then immersed in 3.5% by weight of hydrogen peroxide for 2 hours, and the bath temperature was 5 ° C. Results of measuring the pitting potential when immersed in 3.5 wt% NaCl for samples passivated at 10 ° C, 15 ° C, 25 ° C, and 40 ° C (each 5 temperatures) (center of 5 samples) Value) is shown in FIG.
　温度が５℃以下（５℃を含む）では、試料の半分以上で孔食電位が500mV以下となり、中央値を採っても500ｍＶ前後であり、充分に強い不動態皮膜が形成されないことが理解できる。温度が１０℃になると孔食電位の中央値が1000mＶ前後となり、概ね実用に耐えうる値であることが理解でき、25℃、40℃では全試料が1000mV以上の孔食電位を確保している。 When the temperature is 5 ° C. or less (including 5 ° C.), the pitting corrosion potential is 500 mV or less in more than half of the sample, and even if the median is taken, it can be understood that a sufficiently strong passive film is not formed. . When the temperature reaches 10 ° C, the median value of the pitting corrosion potential is around 1000 mV, and it can be understood that it is a value that can withstand practical use. At 25 ° C and 40 ° C, all samples have a pitting corrosion potential of 1000 mV or more. .
　＜実施例４＞（浴濃度）
　上記ステンレス鋼素材をバフ研磨（No.400）し、上記実施例１と同じ条件で電解研磨した後に、過酸化水素の浸漬温度を25℃、浸漬時間を２時間に固定し浴濃度を変化させた場合の実施例を図４に示す。図４は、各濃度それぞれ５枚の試料を下記の(1)～(9)の濃度の過酸化水素に浸漬して、その孔食電位を測定した結果（５枚の試料の中央値）を示すものである。 <Example 4> (Bath concentration)
After buffing the stainless steel material (No. 400) and electrolytic polishing under the same conditions as in Example 1, the immersion temperature of hydrogen peroxide was fixed at 25 ° C and the immersion time was fixed at 2 hours, and the bath concentration was changed. FIG. 4 shows an embodiment in the case of such a case. Fig. 4 shows the results of measuring the pitting corrosion potential (median value of 5 samples) by immersing 5 samples of each concentration in hydrogen peroxide with the following concentrations (1) to (9). It is shown.
　(1)未処理（電解研磨のみ）、(2)濃度0.98重量％、(3)濃度1.75重量％、(4)濃度3.5重量％、(5)濃度7.0重量％。(6)濃度9.8重量％、(8) 濃度20重量％、(9) 濃度35重量％。 (1) Untreated (electrolytic polishing only), (2) concentration 0.98 wt%, (3) concentration 1.75 wt%, (4) concentration 3.5 wt%, (5) concentration 7.0 wt%. (6) Concentration 9.8% by weight, (8) Soot concentration 20% by weight, (9) Soot concentration 35% by weight.
　前記(2)の試料では、過酸化水素の濃度が１重量％未満（0.98重量％）でも中央値が800mV以上の孔食電位が見られ、まずまずの不動態皮膜ができていると言える。１重量％～３重量％では（例えば1.75重量％）、試料によっては1000mV以下の孔食電位も見られたが、中央値としては1000mV以上あり、十分実用に耐える不動態化膜といえる。過酸化水素の濃度が３重量％を超えると（例えば3.5重量％）、いずれの試料も1000mV以上の孔食電位を得ることができる。 In the sample of (2), a pitting corrosion potential with a median value of 800 mV or more was observed even when the concentration of hydrogen peroxide was less than 1% by weight (0.98% by weight), and it can be said that a moderate passive film was formed. From 1 wt% to 3 wt% (eg, 1.75 wt%), depending on the sample, a pitting corrosion potential of 1000 mV or less was also observed, but the median value is 1000 mV or more, and it can be said that it is a passivated membrane that can withstand practical use. When the concentration of hydrogen peroxide exceeds 3% by weight (for example, 3.5% by weight), any sample can obtain a pitting potential of 1000 mV or more.
　過酸化水素の濃度が20重量％、35重量％でも良質の不動態皮膜が形成されていることから過酸化水素の濃度の上限はないと考えられる。但し、過酸化水素濃度が15重量％を越えると廃棄前に無害化する必要があるので、15重量％以下に抑えるべきである。 Even if the concentration of hydrogen peroxide is 20% by weight or 35% by weight, there is no upper limit of the concentration of hydrogen peroxide because a good quality passive film is formed. However, if the hydrogen peroxide concentration exceeds 15% by weight, it must be detoxified before disposal, so it should be kept below 15% by weight.
　＜実施例５＞NaCl浸漬濃度
　孔食電位の試験液としてのNaClの濃度を変化させたときの孔食電位の測定結果を図５に示す。前記電解研磨した試料を3.5重量％の過酸化水素に２５℃で２時間浸漬して不動態化した試料（図５(b)）を用いた。また、比較のために、電解研磨した試料を30重量％の硝酸溶液に２５℃で2時間浸漬して不動態化した試料（図５(a)）も用いた。 <Example 5> NaCl immersion concentration Fig. 5 shows the measurement results of pitting corrosion potential when the concentration of NaCl as a test solution for pitting corrosion potential was changed. A sample (FIG. 5B) in which the electropolished sample was passivated by immersion in 3.5% by weight of hydrogen peroxide at 25 ° C. for 2 hours was used. For comparison, a sample (FIG. 5 (a)) in which the electropolished sample was passivated by immersion in a 30 wt% nitric acid solution at 25 ° C. for 2 hours was also used.
　硝酸で不動態化した試料（図５(a)）では、NaCl濃度が小さいと（10重量％以下であると）概ね実用に耐えるが、10重量％以上であると極端に孔食電位が低下し、例えばNaCl濃度が25重量％以上（飽和濃度を含む）になると、殆ど実用に耐えうる孔食電位を示さないことが理解できる。 In the sample passivated with nitric acid (Fig. 5 (a)), when the NaCl concentration is small (less than 10% by weight), it can withstand practical use, but when it is more than 10% by weight, the pitting potential is extremely lowered. For example, when the NaCl concentration is 25% by weight or more (including the saturated concentration), it can be understood that the pitting corrosion potential that can withstand practical use is hardly exhibited.
　それに対して、本願発明による試料（図５(b)）は、NaCl濃度が25重量％あるいは飽和濃度に至っても1000mＶ以上の孔食電位を保っていることが理解できる。 On the other hand, it can be understood that the sample according to the present invention (FIG. 5 (b)) maintains a pitting corrosion potential of 1000 mV or more even when the NaCl concentration reaches 25% by weight or the saturation concentration.
　＜実施例６＞NaCl浸漬時間
　不動態化処理後の皮膜の耐久性を調べるために、孔食電位測定前に3.5重量％NaCl溶液に1日～100日浸漬してから孔食電位を測定した。耐久性がないものは短時日で孔食電位が低下するはずである。浸漬後の孔食電位の試験液としてのNaClの濃度は３．５％に固定した。浸漬日数を変化させたときの孔食電位の測定結果を図６に示す。 <Example 6> NaCl immersion time In order to investigate the durability of the film after the passivation treatment, the pitting potential was measured after being immersed in a 3.5 wt% NaCl solution for 1 to 100 days before the pitting potential measurement. . For those not durable, the pitting potential should drop in a short day. The concentration of NaCl as a test solution for pitting potential after immersion was fixed at 3.5%. The measurement result of the pitting corrosion potential when the immersion days are changed is shown in FIG.
　電解研磨した試料を30重量％の硝酸溶液に２５℃で2時間浸漬して不動態化した試料（図６(a)）および、本発明の試料（図６(b)）は、いずれも100日経過しても1000mV以上の孔食電位を維持し、本願発明の試料が、硝酸による不動態化に比して遜色ない耐久性を持っていることが理解できる。 Both the electropolished sample was passivated by immersion in a 30% by weight nitric acid solution at 25 ° C. for 2 hours (FIG. 6 (a)) and the sample of the present invention (FIG. 6 (b)). It can be understood that the pitting corrosion potential of 1000 mV or more is maintained even after a lapse of time, and the sample of the present invention has durability comparable to that of passivation by nitric acid.
　＜比較例＞
　特開2001-115271号公報には、被加工物を有機酸で研磨した後、硝酸および又は過酸化水素を含む酸化性溶剤の液に浸漬して不動態化するようになっている。 <Comparative example>
In Japanese Patent Laid-Open No. 2001-115271, a workpiece is polished with an organic acid and then immersed in an oxidizing solvent containing nitric acid and / or hydrogen peroxide to passivate the workpiece.
　ここで本願発明と関連する項目、有機酸での研磨の後過酸化水素で不動態化する点についての確認実験を図７に示す。 Here, FIG. 7 shows a confirmation experiment on the item related to the present invention, the point of passivation with hydrogen peroxide after polishing with an organic acid.
　バフ研磨したステンレス鋼素材を20重量％、45℃のクエン酸に30分浸漬して表面を研磨し、更に、4.0重量％、45℃の過酸化水素に１時間浸漬した試料と、実施例１と同じ条件で電解研磨し、3.5重量％の過酸化水素に２５℃で２時間浸漬した試料とを3.5重量％のNaCl溶液中でアノード分極したときの孔食電位で比較した。クエン酸処理の試料はせいぜい300mＶの孔食電位であるのに対して、本願発明に掛かる試料は1000mV以上の孔食電位を示した。 A buffed stainless steel material was dipped in 20% by weight, 45 ° C. citric acid for 30 minutes to polish the surface, and further immersed in 4.0% by weight, 45 ° C. hydrogen peroxide for 1 hour, Example 1 The sample was electropolished under the same conditions as above and immersed in 3.5 wt% hydrogen peroxide at 25 ° C. for 2 hours, and compared with the pitting potential when anodically polarized in a 3.5 wt% NaCl solution. The sample treated with citric acid had a pitting corrosion potential of 300 mV at most, whereas the sample according to the present invention showed a pitting corrosion potential of 1000 mV or more.
　従って、単純に不動態化処理に過酸化水素を用いるというだけの発想では充分ではなく、その前処理に電解研磨を用いるということが極めて重要であることが理解できる。 Therefore, the idea of simply using hydrogen peroxide for the passivation treatment is not sufficient, and it can be understood that the use of electropolishing for the pretreatment is extremely important.
　＜ＸＰＳ分析＞
　図８は、従来の方法（電解研磨後３０％硝酸に温度25℃で２時間浸漬）と、本願発明による方法（電解研磨後３．５％の過酸化水素に温度25℃で２時間浸漬）の処理をした試料をＸＰＳ分析した結果を示すものである。 <XPS analysis>
FIG. 8 shows a conventional method (immersion in 30% nitric acid after electropolishing for 2 hours at a temperature of 25 ° C.) and a method according to the present invention (immersion in 3.5% hydrogen peroxide after electropolishing for 2 hours at a temperature of 25 ° C.). 2 shows the result of XPS analysis of a sample that has been subjected to the above treatment.
　従来方法による試料は、0.3分程度のスパッタ時間で鉄分量の増加（クロム量の低下）が見られるのに対して、本願の方法では0.5分程度から同様の現象が見られる。すなわち、クロムリッチ層が厚く、それだけ形成される不動態皮膜が厚いことが理解できる。 The sample by the conventional method shows an increase in the iron content (decrease in the chromium content) in the sputtering time of about 0.3 minutes, whereas the method of the present application shows the same phenomenon from about 0.5 minutes. That is, it can be understood that the chromium-rich layer is thick and the passive film to be formed is thick.
　以上説明したように、本発明は不動態化処理に廃棄に前処理の不要な過酸化水素を用いることができるので、環境観点、コスト観点からの利点が大きく、産業の利用可能性は極めて大きい。 As described above, the present invention can use hydrogen peroxide that does not require pretreatment for disposal in the passivating process, and therefore has great advantages from the environmental and cost viewpoints, and the industrial applicability is extremely large. .

Claims (3)

  1. 　被処理物を電解研磨するステップと、
    　上記電解研磨された被処理物を過酸化水素に浸漬するステップ
    を備えたことを特徴とするステンレス鋼の不動態化方法。     Electropolishing the workpiece; and
    A method for passivating stainless steel, comprising the step of immersing the electropolished workpiece in hydrogen peroxide.
  2. 　上記電解研磨は、電解液が硫酸とリン酸の混合液であり、当該混合液が８５％のリン酸と９８％の硫酸を用いた場合、リン酸と硫酸の比が、５０％～９０％：１０％～５０％（容量％）であり、温度３０℃～８０℃、電流１A～２０A／dm2、時間３０秒～６０分で行なう請求項１に記載のステンレス鋼の不動態化方法。 In the electrolytic polishing, when the electrolytic solution is a mixed solution of sulfuric acid and phosphoric acid, and the mixed solution uses 85% phosphoric acid and 98% sulfuric acid, the ratio of phosphoric acid to sulfuric acid is 50% to 90%. The method for passivating stainless steel according to claim 1, which is carried out at a temperature of 30 ° C to 80 ° C, a current of 1 A to 20 A / dm 2 and a time of 30 seconds to 60 minutes.
  3. 　上記過酸化水素水への浸漬は、過酸化水素濃度１重量％以上、温度１０℃以上、浸漬時間３０分以上でおこなう請求項１に記載のステンレス鋼の不動態化方法。 The method for passivating stainless steel according to claim 1, wherein the immersion in the hydrogen peroxide solution is performed at a hydrogen peroxide concentration of 1% by weight or more, a temperature of 10 ° C or more, and an immersion time of 30 minutes or more.
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JP2016037630A (en) * 2014-08-07 2016-03-22 有限会社コンタミネーション・コントロール・サービス Corrosion prevention method
JP2016108640A (en) * 2014-12-10 2016-06-20 株式会社Ihi Method and solution for passivating stainless steel component
JP2017082253A (en) * 2015-10-22 2017-05-18 株式会社Ihi Descaling treatment method of stainless steel component, and passivation treatment method
CN106757298A (en) * 2016-12-21 2017-05-31 江苏和兴汽车科技有限公司 A kind of Chrome-free electropolishing liquid, the method for aluminium alloy electric polishing and automobile aluminum decoration
CN106757298B (en) * 2016-12-21 2019-08-02 江苏和兴汽车科技有限公司 A kind of Chrome-free electropolishing liquid, aluminium alloy electric polishing method and automobile aluminum decoration
JP2018188728A (en) * 2017-05-08 2018-11-29 株式会社アサヒメッキ Stainless steel having hydrogen barrier capability and method for producing the same
CN109208058A (en) * 2017-07-04 2019-01-15 北京首航科学技术开发有限公司 A kind of surface treatment method improving 17-4PH material antiseptic corrosion energy
CN109208058B (en) * 2017-07-04 2020-10-23 北京首航科学技术开发有限公司 Surface treatment method for improving corrosion resistance of 17-4PH material
JP2019052379A (en) * 2019-01-15 2019-04-04 株式会社Ihi Method and solution for passivating stainless steel component
JP2020109217A (en) * 2020-04-20 2020-07-16 株式会社Ihi Treatment method of stainless steel component
JP7038751B2 (en) 2020-04-20 2022-03-18 株式会社Ihi How to handle stainless steel parts
CN111829941A (en) * 2020-05-27 2020-10-27 盐城工学院 Corrosive liquid for detecting gallium oxide single crystal processing surface damage layer and detection method

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