Surface anti-corrosion treatment and coloring method of stainless steel component

Abstract

The invention relates to a surface anti-corrosion treatment and coloring method for a stainless steel component. According to the surface anti-corrosion treatment and coloring method for the stainless steel component, pollutants such as impurities and oil stains on the surface of the stainless steel component can be removed through chemical oil removal and alkali corrosion treatment; through oxidation treatment, Cr and Mo elements can be introduced to the surface of the stainless steel component, and a surface passivation layer is formed, so that the corrosion resistance of the stainless steel component is enhanced; and through electrolytic treatment, the stainless steel component is subjected to hole sealing treatment, and the corrosion resistance of the stainless steel component is further enhanced. And through hardening treatment, the corrosion resistance of the stainless steel component is further enhanced. And moreover, the CrO3 concentration and the oxidation treatment duration are adjusted, so that the surface of the stainless steel component subjected to surface treatment can present different colors. According to the surface anti-corrosion treatment and coloring method for the stainless steel component, the anti-corrosion performance of the stainless steel component is greatly improved, the equipment requirement is low, therefore, the treatment cost is low, and the attractiveness of the stainless steel component can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment of stainless steel components, and particularly to a surface anti-corrosion treatment and coloring method for stainless steel components. Background Art

[0002] In the petrochemical industry, material corrosion not only comes from the direct erosion of chemical media, but more importantly, it is the result of the combined action under high temperature, high pressure and continuous operation conditions in actual production. The stainless steel surface strengthening technology and recycling remanufacturing of petrochemical tower internals involve multiple disciplines and fields such as petrochemical industry, materials, mechanical equipment, electrochemistry, etc., with complex technology and great difficulty in tackling key problems.

[0003] At present, there are many methods to prevent metal corrosion: 1. Directly treating the corrosion medium, which is convenient when the corrosion medium is less, but very troublesome when the corrosion medium components are more, such as corrosion in seawater treatment; 2. Coating or plating non-metallic materials, non-metallic protective layers or inactive metal materials, metal protective layers on the metal surface; 3. Improving the inherent corrosion resistance of metal materials, such as doping some corrosion-resistant elements inside the metal materials; 4. Electrochemical protection, by connecting a more active material to prevent the protected metal from corroding, or making the structure become the protected cathode through an external circuit; 5. The surface treatment method of forming a metal protective layer on the metal surface is to coat a layer of inactive metal or alloy on the surface of the metal component as a protective layer to slow down the corrosion rate, or electroplating a layer of metal or alloy on the metal surface by electro-deposition method, but the defect of this method is that the fusion of the coating metal and the protected metal is not good, and the coating is rigid and easy to peel off.

[0004] Therefore, the traditional methods for preventing metal corrosion have complex treatment processes, great difficulty, are not suitable for large-scale production, and cannot meet the actual requirements of anti-corrosion ability. Summary of the Invention

[0005] Based on this, it is necessary to provide a surface anti-corrosion treatment and coloring method for stainless steel components that can improve the anti-corrosion effect, has a simple process, low equipment requirements, and can improve the surface aesthetics of stainless steel components.

[0006] A surface anti-corrosion treatment and coloring method for stainless steel components includes the steps of:

[0007] Performing chemical degreasing and alkali etching treatment on the surface of the stainless steel component;

[0008] Performing the first water washing treatment on the stainless steel component after chemical degreasing and alkali etching treatment;

[0009] Place the stainless steel component after the first water wash in an oxidation solution for surface oxidation treatment; the oxidation solution includes chromium trioxide and sodium molybdate;

[0010] Conduct a second water wash treatment on the stainless steel component after the oxidation treatment;

[0011] Use the surface of the stainless steel component after the second water wash as the cathode and immerse it in an electrolyte solution for electrolysis treatment;

[0012] Conduct a third water wash treatment on the stainless steel component after the electrolysis treatment;

[0013] Conduct a hardening treatment on the stainless steel component after the third water wash treatment.

[0014] In one embodiment, the steps of chemically degreasing and alkali etching the surface of the stainless steel component are: place the stainless steel component in a degreasing and alkali etching solution at a first preset temperature for a first preset time to chemically degrease and alkali etch the surface of the stainless steel component.

[0015] In one embodiment, the first preset temperature is 75°C to 85°C, and the first preset time is 12 minutes to 18 minutes.

[0016] In one embodiment, the degreasing and alkali etching solution, by solution percentage concentration, includes 6% to 8% sodium hydroxide and 0.4% to 0.6% ethoxy-modified polysilane.

[0017] In one embodiment, the step of placing the stainless steel component after the first water wash in an oxidation solution for surface oxidation treatment is: place the stainless steel component after the first water wash in an oxidation solution at a second preset temperature for a second preset time to oxidize the surface of the stainless steel component.

[0018] In one embodiment, the oxidation solution includes 240 g / L to 360 g / L of CrO3, 120 g / L to 160 g / L of Na2MoO4, and 470 g / L to 490 g / L of H2SO4.

[0019] In one embodiment, the step of using the surface of the stainless steel component after the second water wash as the cathode and immersing it in an electrolyte solution for electrolysis treatment is: place the stainless steel component after the second water wash in an electrolyte solution at a third preset temperature for a third preset time to conduct electrolysis treatment on the stainless steel component.

[0020] In one embodiment, the electrolyte comprises 90 g / L to 110 g / L of CrO3, 90 g / L to 110 g / L of Na2MoO4, 185 g / L to 215 g / L of H3PO4, 50 g / L to 60 g / L of Na2SiO3, and 470 g / L to 490 g / L of H2SO4.

[0021] In one embodiment, the current during the electrolytic treatment is direct current, and the current intensity is 0.4 A / cm 2 to 1.1 A / cm 2 .

[0022] In one embodiment, the steps for hardening the stainless steel member after the third water washing treatment are: placing the stainless steel member after the third water washing treatment in an environment at a fourth preset temperature for a fourth preset time to harden the stainless steel member.

[0023] The above-mentioned surface anti-corrosion treatment and coloring method for stainless steel members removes impurities, oil stains and other pollutants on the surface of the stainless steel member by chemically degreasing and alkali etching the surface of the stainless steel member; through the oxidation treatment, not only Cr element and Mo element are introduced on the surface of the stainless steel member, but also a surface passivation layer is formed on the surface of the stainless steel member to enhance the corrosion resistance of the stainless steel member; through the electrolytic treatment, under the action of the current, the stainless steel member is used as the cathode to perform hole sealing treatment on the stainless steel member, thereby further enhancing the corrosion resistance of the stainless steel member. Through the hardening treatment, the corrosion resistance of the stainless steel member is further enhanced. Moreover, during the oxidation treatment, by adjusting the CrO3 concentration and the oxidation treatment duration, the surface of the stainless steel member after surface treatment can present different colors, making the surface of the stainless steel member more beautiful. Therefore, the above-mentioned surface anti-corrosion treatment and coloring method for stainless steel members can not only greatly improve the corrosion resistance of stainless steel members, but also has a simple process, does not require the introduction of special or large equipment, so the treatment cost is low, and can improve the aesthetics of stainless steel members. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic flow chart of the surface anti-corrosion treatment and coloring method for stainless steel members in a preferred embodiment of the present invention;

[0025] Figure 2 is Figure 1 the surface oxidation - cyclic polarization curve diagram of 304 stainless steel under different oxidation conditions in the surface anti-corrosion treatment and coloring method of the stainless steel member shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0028] When describing positional relationships, unless otherwise specified, when an element is referred to as being "on" another element, it can be directly on the other element or there can also be intermediate elements. It can also be understood that when an element is referred to as being "between" two elements, it can be the only one between the two elements or there can also be one or more intermediate elements.

[0029] In the case of using "including", "having", and "comprising" described herein, unless explicit limiting terms are used, such as "only", "consisting of", etc., another component can also be added. Unless otherwise mentioned, terms in the singular form can include the plural form and should not be understood as having a quantity of one.

[0030] Please refer to Figure 1 , the surface anti-corrosion treatment and coloring method of the stainless steel member in the preferred embodiment of the present invention includes steps S10 to S70.

[0031] Step S10, chemically degrease and alkali-etch the surface of the stainless steel member.

[0032] To ensure the stable reliability of the degreasing and alkali-etching treatment effects, specifically, place the stainless steel member in a degreasing and alkali-etching solution at a first preset temperature for a first preset time to chemically degrease and alkali-etch the surface of the stainless steel member. More specifically, the first preset temperature is 75°C to 85°C, and the first preset time is 12 minutes to 18 minutes.

[0033] To ensure the degreasing and alkali-etching effects, specifically, the degreasing and alkali-etching solution includes 6% to 8% sodium hydroxide and 0.4% to 0.6% ethoxy-modified polysilane by solution concentration percentage

[0034] Step S20, perform the first water washing treatment on the stainless steel component after chemical degreasing and alkaline etching. In this way, by executing Step S20, the degreasing and alkaline etching solution on the surface of the stainless steel component is cleaned to ensure the effect and reliability of subsequent oxidation treatment.

[0035] Step S30, place the stainless steel component after the first water washing treatment in an oxidation solution for surface oxidation treatment. The oxidation solution includes chromium trioxide and sodium molybdate. To ensure the oxidation treatment effect, the oxidation solution includes 240 g / L - 360 g / L of CrO3, 120 g / L - 160 g / L of Na2MoO4, and 470 g / L - 490 g / L of H2SO4.

[0036] To ensure the stable reliability of the oxidation effect, specifically, the stainless steel component after the first water washing is placed in the oxidation solution at the second preset temperature for the second preset time to perform surface oxidation treatment on the stainless steel component. More specifically, the second preset temperature is 75°C - 85°C, and the second preset time is 18 minutes - 62 minutes.

[0037] Step S40, perform the second water washing treatment on the stainless steel component after oxidation treatment.

[0038] In this way, by executing Step S40, the oxidation solution attached to the surface of the stainless steel component is cleaned to ensure the effect of subsequent electrolysis treatment.

[0039] Step S50, immerse the surface of the stainless steel component after the second water washing treatment as the cathode in the electrolyte for electrolysis treatment.

[0040] To ensure the stable reliability of the electrolysis treatment effect, specifically, the stainless steel component after the second water washing is placed in the electrolyte at the third preset temperature for the third preset time to perform electrolysis treatment on the stainless steel component. More specifically, the third preset temperature is 48°C - 56°C, and the third preset time is 18 minutes - 22 minutes.

[0041] Step S60, perform the third water washing treatment on the stainless steel component after electrolysis treatment. In this way, by executing Step S60, the electrolyte on the surface of the stainless steel component is cleaned to ensure the effect and reliability of subsequent hardening treatment.

[0042] Step S70, perform hardening treatment on the stainless steel component after the third water washing treatment.

[0043] Specifically, the stainless steel component after the third water washing is placed in an environment at the fourth preset temperature for the fourth preset time to perform hardening treatment on the stainless steel component. More specifically, the fourth preset temperature is 56°C - 64°C, and the fourth preset time is 18 minutes - 22 minutes.

[0044] In order to improve the water washing effect and the efficiency of stainless steel surface treatment, in some embodiments, during the first water washing treatment, the second water washing treatment, and the third water washing treatment, the stainless steel component is cleaned with water at room temperature for 2 to 4 minutes.

[0045] Thus, by performing step S10, contaminants such as impurities and oil stains on the surface of the stainless steel component are removed. By performing step S20, the degreasing and alkaline etching solution attached to the stainless steel surface during the execution of step S10 is washed away. By performing step S30, not only Cr element and Mo element are introduced onto the surface of the stainless steel component, but also a surface passivation layer is formed on the surface of the stainless steel component to enhance the corrosion resistance of the stainless steel component. By performing step S40, the oxidation solution attached to the surface of the stainless steel component during the execution of step S30 is washed away. By performing step S50, under the action of an electric current, the stainless steel component is used as the cathode to perform a sealing treatment on the stainless steel component, thereby further enhancing the corrosion resistance of the stainless steel component. By performing step S60, the electrolyte solution attached to the surface of the stainless steel component during the execution of step S50 is washed away. By performing step S70, the stainless steel component after oxidation treatment and electrolysis treatment is hardened to further enhance the corrosion resistance of the stainless steel component.

[0046] Moreover, when performing step S30, by adjusting the concentration of CrO3 and the oxidation duration, the surface of the stainless steel component after surface treatment can exhibit different colors. It has been proven through practice that when the concentration of CrO3 is 250 g / L and the oxidation time is 60 minutes, the surface of the oxidized stainless steel component is dark green; when the concentration of CrO3 is 350 g / L and the oxidation time is 40 minutes, the surface of the oxidized stainless steel component is reddish brown. Therefore, compared with the stainless steel component without oxidation treatment, the color of the oxidized stainless steel component is more vivid.

[0047] Therefore, by performing the above steps S10 to S70, the surface anti-corrosion treatment and coloring treatment of the stainless steel component are completed, which not only makes the stainless steel component have higher corrosion resistance, but also improves the surface aesthetic degree of the stainless steel component.

[0048] In order to clarify the effect of the above-mentioned surface anti-corrosion treatment and coloring method of the stainless steel component on the anti-corrosion performance, the surface oxidation-cyclic polarization curves of the stainless steel component under different oxidation conditions as shown in Figure 2 are recorded. Figure 2Figures (a) to (h) are the cyclic potentiodynamic polarization curves of 304 stainless steel under different oxidation treatment conditions in a 3.5 wt.% NaCl solution, and (j) is untreated 304 stainless steel. First, as the voltage increases, all samples have a corrosion potential, but the corrosion potential of the uncoated 304 stainless steel is the lowest, indicating the worst corrosion resistance. In addition, as the voltage continues to increase, the current in the uncoated 304 stainless steel suddenly rises, indicating pitting corrosion, which does not occur in the coated stainless steel. During the reverse scan, due to the thickening of the passive film, the corrosion resistance of the material increases, and the current density decreases during the reverse scan, indicating that the coated stainless steel has better corrosion protection performance.

[0049] Furthermore, according to Figure 2 the oxidation-cycle curve of the 304 stainless steel surface shown, the test results are analyzed as shown in Table 1 below:

[0050] Table 1 Analysis of the test results of the oxidation-cyclic polarization curve of the 304 stainless steel surface

[0051]

[0052] As can be seen from the above table, compared with the uncoated specimen of 304 stainless steel, the corrosion potential E corr of the material after surface oxidation treatment has been significantly improved, indicating that the oxidation treatment has improved the corrosion resistance of the material. If the repassivation potential E rep of the stainless steel is higher, it indicates that the stainless steel has stronger corrosion resistance and can maintain better corrosion resistance even under extreme corrosion conditions. Also, based on the results of the cyclic polarization curve, the surface self-repair ability of the stainless steel components treated by the above method has been significantly improved, far stronger than that of the untreated 304 stainless steel. Obviously, the corrosion resistance of the stainless steel components treated by the above surface corrosion protection and coloring method of stainless steel components has indeed been greatly improved.

[0053] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0054] The above-described embodiments merely represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A surface anti-corrosion treatment and coloring method for a stainless steel component, characterized in that, Including the steps: Conduct chemical degreasing and alkaline etching on the surface of the stainless steel component; Conduct the first water washing treatment on the stainless steel component after chemical degreasing and alkaline etching; Place the stainless steel component after the first water washing in an oxidation solution for surface oxidation treatment; the oxidation solution includes chromium trioxide and sodium molybdate; Conduct the second water washing treatment on the stainless steel component after oxidation treatment; Immerse the surface of the stainless steel component after the second water washing as the cathode in an electrolyte for electrolysis treatment; Conduct the third water washing treatment on the stainless steel component after electrolysis treatment; Conduct hardening treatment on the stainless steel component after the third water washing treatment.

2. The surface anti-corrosion treatment and coloring method of the stainless steel member according to claim 1, characterized in that, The step of conducting chemical degreasing and alkaline etching on the surface of the stainless steel component is: Place the stainless steel component in a degreasing and alkaline etching solution at the first preset temperature for the first preset time to conduct chemical degreasing and alkaline etching on the surface of the stainless steel component.

3. The surface anti-corrosion treatment and coloring method of the stainless steel component according to claim 2, characterized in that, The first preset temperature is 75°C to 85°C, and the first preset time is 12 minutes to 18 minutes.

4. The surface anti-corrosion treatment and coloring method of the stainless steel member according to claim 2, characterized in that, The degreasing and alkaline etching solution includes 6% to 8% sodium hydroxide and 0.4% to 0.6% ethoxy-modified polysilane according to the solution percentage concentration.

5. The surface anti-corrosion treatment and coloring method of the stainless steel component according to claim 1, characterized in that, The step of placing the stainless steel component after the first water washing in an oxidation solution for surface oxidation treatment is: Place the stainless steel component after the first water washing in an oxidation solution at the second preset temperature for the second preset time to conduct oxidation treatment on the surface of the stainless steel component.

6. The surface anti-corrosion treatment and coloring method of the stainless steel component according to claim 1, characterized in that, The oxidation solution includes 240 g / L to 360 g / L of CrO3, 120 g / L to 160 g / L of Na2MoO4, and 470 g / L to 490 g / L of H2SO4.

7. The surface anti-corrosion treatment and coloring method of the stainless steel member according to claim 1, characterized in that, The step of immersing the surface of the stainless steel component after the second water washing as the cathode in an electrolyte for electrolysis treatment is: Place the stainless steel component after the second water washing in an electrolyte at the third preset temperature for the third preset time to conduct electrolysis treatment on the stainless steel component.

8. The surface anti-corrosion treatment and coloring method of the stainless steel member according to claim 1, characterized in that, The electrolyte includes 90 g / L to 110 g / L of CrO3, 90 g / L to 110 g / L of Na2MoO4, 185 g / L to 215 g / L of H3PO4, 50 g / L to 60 g / L of Na2SiO3, and 470 g / L to 490 g / L of H2SO4.

9. The surface anti-corrosion treatment and coloring method of the stainless steel component according to claim 1, characterized in that, The current during the electrolytic treatment is direct current, and the current intensity is 0.4 A / cm 2 ~1.1 A / cm 2 .

10. The surface anti-corrosion treatment and coloring method of the stainless steel member according to claim 1, characterized in that, The step of conducting hardening treatment on the stainless steel component after the third water washing treatment is: Place the stainless steel component after the third water washing in an environment at the fourth preset temperature for the fourth preset time to conduct hardening treatment on the stainless steel component.

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