Corrosion-resistant metal plate as well as preparation method and application thereof

Abstract

The invention discloses a corrosion-resistant metal plate as well as a preparation method and application thereof, and belongs to the field of metal corrosion prevention. The method comprises the following steps: placing a pretreated metal plate and organic amine and / or polyphenol organic matters in a closed space, controlling the relative humidity of the closed space to be less than or equal to 30%, and evaporating for 5-15 minutes at the temperature of 50-150 DEG C, so that the part, needing to be treated, of the metal plate is in full contact with organic steam; and maintaining the temperature of the closed space at 40-500 DEG C, standing for 1-30 minutes to obtain a compact organic film with the thickness of 1-200 microns, and finally spraying finishing paint on the organic film to obtain a target product.

Description

Technical Field

[0001] The invention belongs to the field of metal anticorrosion, and particularly relates to a method for improving corrosion resistance. Background Art

[0002] Corrosion poses a major threat to human production and life, not only causing economic losses, but also polluting the environment, threatening production safety and human life and health. Therefore, improving the corrosion resistance of metals has always been a difficult problem to be solved, especially in harsh marine environments. Among the many anti-corrosion technologies, constructing a nano-protective film on the metal surface, such as an organic film or a carbon film, is an effective way to improve corrosion resistance.

[0003] Self-assembly technology can form a nano-layer organic film on the surface. Studies have found that organic amines and polyphenols will self-assemble on the surface, where the amine group forms a coordination bond with the metal by sharing electron pairs with the metal, and is tightly linked to the metal; and the phenolic hydroxyl groups in tannic acid will form a cross-linked layer through hydrogen bonds. This organic film can act as a barrier to isolate the corrosive medium and play an anti-corrosion role. For example, octadecylamine is currently mainly used in boiler corrosion protection, but it needs to be added to the pipeline at around 400°C. It is easy to decompose if the temperature is too high, and the effect is poor if the temperature is too low. In short, self-assembly has strict requirements on the environment, will produce waste liquid, and the self-assembled film formed is not dense, so it is not suitable for widespread industrial application.

[0004] Chemical vapor deposition is a chemical technology that mainly uses one or more gas phase compounds or single substances containing film elements to chemically react on the substrate surface to form a film. For example, using acetylene through plasma chemical vapor deposition (PECVD) can obtain graphene carbon film after surface reaction. However, this method usually requires particularly expensive equipment, which greatly increases production costs.

[0005] Therefore, there is an urgent need to develop a method for constructing a nanolayer on the metal surface that is low-cost, can improve corrosion resistance, and is suitable for industrial widespread application and production. Summary of the invention

[0006] The present invention is to provide a method for constructing a nanolayer on a metal surface which is low-cost and suitable for industrial widespread application and production, so as to improve its corrosion resistance.

[0007] A method for preparing a corrosion-resistant metal plate comprises placing a pretreated metal plate and an organic amine and / or polyphenol organic matter in a closed space, controlling the relative humidity of the closed space to be ≤30%, performing evaporation at a temperature of 50 to 150°C for 5 to 15 minutes, so that the portion of the metal plate to be treated is fully in contact with the organic vapor; then maintaining the temperature of the closed space at 40 to 500°C and standing for 1 to 30 minutes, thereby obtaining a dense organic film with a thickness of 1 to 200 μm, and finally spraying a topcoat on the organic film to obtain a target product.

[0008] In the technical solution of the present invention: the relative humidity is 5-10%.

[0009] In the technical solution of the present invention: the atmosphere of the enclosed space is one of air, nitrogen, argon or vacuum atmosphere.

[0010] In the technical solution of the present invention: the organic amine is selected from at least one of tetradecylamine, hexadecylamine and octadecylamine; and the polyphenol organic matter is tannic acid.

[0011] In the technical solution of the present invention, the molar ratio between the organic amine and the polyphenol organic matter is 1-5:0.1-5.

[0012] In the technical solution of the present invention, the molar ratio between the organic amine and the polyphenol organic matter is 1:0.1-1.

[0013] A metal plate with corrosion resistance is prepared by the above method.

[0014] In the technical solution of the present invention, the corrosion-resistant metal plate is used in salt lake and ocean corrosion protection.

[0015] In the technical solution of the present invention, the pretreatment of the metal plate includes but is not limited to surface dust removal, stain removal and rust removal.

[0016] In the technical solution of the present invention, the portion of the metal plate that needs to be processed may be one side of the metal plate or the front and back sides of the metal plate.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The method is simple. The present invention uses a simple evaporation process to deposit organic matter onto the treated metal surface, which is only a physical process.

[0019] 2. Low cost. Compared with chemical vapor deposition, it does not require special equipment and has no restrictions on metal shape and size.

[0020] 3. No waste liquid is generated. Compared with the self-assembly method, it does not require a special self-assembly environment, nor does it require organic solvents.

[0021] 4. Improved corrosion resistance. In the present invention, the nano-organic film is cured to generate forces between the obtained nano-organic film and the metal, and the carbon film is dense and stable, and also provides a hydrophobic surface, which is more conducive to the stable film formation of the surface anti-corrosion paint, and finally improves the corrosion resistance, making it more suitable for application in harsh conditions such as oceans and salt lakes.

[0022] 5. Suitable for widespread industrialization. Based on the above benefits, organic matter not limited to the present invention can also be used for film formation according to actual industrial process needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 .Impedance diagram of carbon steel modified by octadecylamine evaporation and then sprayed with polyurethane coating.

[0024] Figure 2 .Impedance diagram of composite carbonized film compared with plasma enhanced chemical vapor deposition.

[0025] Figure 3 Untreated carbon steel sheet (left) and carbonized carbon steel sheet with tetradecylamine and tannic acid (right).

[0026] Figure 4 .Raman spectrum of tannic acid carbonized film under vacuum environment at 500℃.

[0027] Figure 5 .Impedance diagram of carbon steel modified by self-assembly method and then sprayed with polyurethane coating. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto:

[0029] The polyurethane anti-corrosion paint is a commercially available product. The polyurethane anti-corrosion paint used in the embodiments or comparative examples is Hempel brand polyurethane topcoat 55610, and the thickness of the anti-corrosion paint coating is 100 μm±10 μm.

[0030] Example 1

[0031] First, the carbon steel surface is dusted, destained and rusted, and then placed in a closed space at room temperature, with the relative humidity controlled at 8%. Octadecylamine is evaporated at 50°C in an air atmosphere for 10 minutes, and then the evaporation is stopped; the closed space is maintained at 50°C for 20 minutes to obtain a dense organic film with a thickness of 150nm; finally, the carbon steel treated above is sprayed with polyurethane anticorrosive paint, and the thickness of the anticorrosive paint coating is 100μm±10μm (the same below). Through electrochemical impedance spectroscopy, it is seen Figure 1 Compared with carbon steel sprayed with polyurethane, it was found that its electrochemical impedance performance was improved by more than 5 times, which means that the corrosion resistance was improved.

[0032] The electrochemical impedance test was conducted using a VersaSTAT 3A electrochemical workstation (Princeton). The electrolytic cell was a three-electrode system, with a Pt electrode as the counter electrode, a mercury / mercury oxide (Hg / HgO) electrode as the reference electrode, a 3.5% NaCl solution as the electrolyte, and the non-test part was encapsulated with epoxy resin. The open circuit point was continuously monitored for 30 minutes to obtain a stable potential. After the potential stabilized, the electrochemical impedance measurement was performed. The operating frequency range was selected from 0.01Hz to 100000Hz, and the amplitude of the external AC signal was 10mV. (The same below)

[0033] Example 2

[0034] First, the carbon steel surface was dusted, destained and rusted, and then placed in a closed space at room temperature, with the relative humidity controlled at 10%. Octadecylamine was evaporated at 80°C in a nitrogen atmosphere for 5 minutes, and then the evaporation was stopped. The closed space was then maintained at 150°C for 20 minutes to obtain a dense organic film with a thickness of 80nm. Finally, the carbon steel treated above was sprayed with polyurethane anticorrosive paint, and the thickness of the anticorrosive paint coating was 100μm±10μm. Through impedance analysis, it was seen Figure 1 Compared with carbon steel sprayed with polyurethane, it was found that its impedance performance was improved by more than 5 times, which means that the corrosion resistance was improved.

[0035] Example 3

[0036] After removing dust, stains and rust from the carbon steel surface, place it in a closed space at room temperature, control the relative humidity at 5%, evaporate hexadecylamine at 50°C in an argon atmosphere, and stop evaporating after 10 minutes; then maintain the closed space at 500°C for 5 minutes to obtain a 10nm thick dense carbon film; finally, spray the carbon steel treated above with polyurethane anticorrosive paint, and the thickness of the anticorrosive paint coating is 100μm±10μm. Through impedance analysis, it is found that its impedance performance has increased by nearly 4 times compared with carbon steel, which means that corrosion resistance has been improved.

[0037] Example 4

[0038] The carbon steel surface was first dusted, destained and derusted, and then placed in a closed space at room temperature. Tetradecamine and tannic acid (molar ratio 1:0.5) were evaporated at 150°C under vacuum conditions. After evaporation for 15 minutes, the evaporation was stopped. The closed space was then maintained at 500°C for 5 minutes to obtain a 200nm thick dense carbon film. Figure 3 ; Raman spectrum see Figure 4 , D(1350) and G(1580) peaks can be seen, indicating that it is an amorphous carbon film. Figure 2 ( Figure 2 Only the impedance performance of the steel without anti-corrosion paint and with nano-film on the surface was compared. Compared with carbon steel, it was found that its impedance performance increased by more than 4 times, which means that the corrosion resistance was improved.

[0039] Comparative Example 1

[0040] The carbon film was prepared by plasma enhanced chemical vapor deposition (PECVD). The system was evacuated to high vacuum, nitrogen (purity ≥ 99.99%) was filled into the system, and after the pressure was stabilized, acetylene and hydrogen (Nanjing special gas, purity ≥ 99.99%) were passed into the system. The system was heated to 800℃ and heated for 1h to obtain a 20nm thick carbon film on the carbon steel surface. Impedance analysis is shown in Figure 2 Its impedance is 2.5 times that of carbon steel, but it is not as good as the carbonized film of tetradecylamine + tannic acid.

[0041] Comparative Example 2

[0042] Using the self-assembly method, hexadecylamine, octadecylamine and tannic acid were assembled on the surface of carbon steel respectively, and then sprayed with polyurethane paint. Compared with the untreated carbon steel sprayed with polyurethane paint, the self-assembly of hexadecylamine was lower; the self-assembly of octadecylamine was equivalent; the self-assembly of tannic acid was slightly improved, about 1.5 times. Figure 5 .

[0043] Comparative Example 3

[0044] After removing dust, stains and rust from the carbon steel surface, place it in a closed space at room temperature, control the relative humidity at 10%, and evaporate hexadecylamine at 80°C in an argon atmosphere. After evaporation for 10 minutes, stop evaporation; spray polyurethane anticorrosive paint on the carbon steel treated as above. By impedance analysis, compared with carbon steel sprayed with polyurethane, it is found that its impedance performance is improved by 1.1 times, and its corrosion resistance is slightly improved.

Claims

1. A method for preparing a corrosion-resistant metal plate, characterized in that: The method places the pretreated metal plate and organic amine and / or polyphenol organic matter in a closed space, controls the relative humidity of the closed space to be ≤30%, and evaporates at a temperature of 50-150°C for 5-15 minutes, so that the part of the metal plate to be treated is fully in contact with the organic vapor; then maintains the temperature of the closed space at 40-500°C and stands for 1-30 minutes, so as to obtain a dense organic film with a thickness of 1-200 μm, and finally sprays a topcoat on the organic film to obtain a target product.

2. The method for preparing a corrosion-resistant metal plate according to claim 1, characterized in that: The relative humidity is 5-10%.

3. The method for preparing a corrosion-resistant metal plate according to claim 1, characterized in that: The atmosphere of the enclosed space is one of air, nitrogen, argon or vacuum atmosphere.

4. The method for preparing a corrosion-resistant metal plate according to claim 1, characterized in that: The organic amine is selected from at least one of tetradecylamine, hexadecylamine and octadecylamine; and the polyphenol organic matter is tannic acid.

5. The method for preparing a corrosion-resistant metal plate according to claim 1 or 4, characterized in that include: The molar ratio between the organic amine and the polyphenol organic matter is 1-5:0.1-5.

6. The method for preparing a corrosion-resistant metal plate according to claim 5, characterized in that include: The molar ratio between the organic amine and the polyphenol organic matter is 1:0.1~1.

7. A corrosion-resistant metal plate, characterized in that: The method is prepared by the method described in any one of claims 1 to 6.

8. The corrosion-resistant metal plate according to claim 1 is used in salt lake and ocean corrosion protection.

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