Oriented silicon steel coating surface sealing treatment method for marine environment

Abstract

The invention provides an oriented silicon steel coating surface sealing treatment method for a marine environment. A used sealing treatment solution comprises the following components in percentage by mass: 15-35% of rare earth metal salt, 1-5% of a polydopamine complexing agent, 1-5% of a Tris and Na2MoO4 corrosion inhibitor, 0.5-2% of a polyethylene glycol or phytic acid active agent and the balance of water, and the pH value of a system is 8-9. The oriented silicon steel coating surface sealing treatment method for the marine environment, provided by the invention, is simple in production process, non-toxic, free of environmental pollution, low in cost, good in stability and beneficial to expanded production, and has very high industrial application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of oriented silicon steel coatings, and in particular to a surface sealing treatment method for oriented silicon steel coatings for marine environments. Background Art

[0002] Oriented silicon steel is an important soft magnetic material, widely used in power transformers and other fields. With the continuous improvement of the country's requirements for energy conservation and environmental protection and the adjustment of energy structure, the performance of oriented silicon steel has received increasing attention. The special high humidity, high salinity and complex meteorological changes in the marine environment have put forward higher requirements for oriented silicon steel. However, the corrosion resistance of existing oriented silicon steel coatings in the marine environment is limited and cannot meet the requirements of long-term use. This is because the surface coating of oriented silicon steel must first have good insulation performance to reduce core loss and improve the lamination coefficient, while preventing silicon steel sheet corrosion and improving the bonding performance of silicon steel sheets. CN 105567019 A discloses a chromium-free environmentally friendly oriented silicon steel insulating coating and a preparation method thereof, which has good insulation performance and good punching performance and lamination coefficient. CN111793421 A discloses an environmentally friendly chromium-free insulating coating liquid for surface treatment of oriented silicon steel, which improves the film-forming property, hygroscopicity resistance, corrosion resistance, adhesion, heat resistance, insulation and moisture and heat resistance of the surface of oriented silicon steel. These patents can improve the corrosion resistance of oriented silicon steel, but their corrosion resistance is limited in the marine environment. CN101519775A discloses an environmentally friendly electro-galvanized chromium-free phosphating sealed steel plate and a manufacturing method thereof. The patent is mainly used for the sealing treatment of steel plates after phosphating. Currently, commonly used sealing methods include chromate sealing, phosphate sealing, etc., but these methods have problems such as environmental pollution and limited corrosion resistance. Summary of the invention

[0003] In order to maintain the insulation of oriented silicon steel while overcoming the problem of insufficient corrosion resistance of oriented silicon steel, the purpose of the present invention is to provide a surface sealing treatment method for oriented silicon steel coating for marine environment, so as to further improve the corrosion resistance of oriented silicon steel in marine environment and extend its service life. The good wettability of polydopamine and photosensitive resin is further treated to form a hydrophobic layer. Secondly, a surface sealing treatment method for oriented silicon steel coating for marine environment is provided, which has simple production process, non-toxicity, no environmental pollution, low cost, good stability, is conducive to expanding production, and has very high industrial application prospects.

[0004] To achieve the above object, the present invention adopts the following technical solution: A sealing treatment liquid for sealing treatment of the surface of oriented silicon steel coating, the sealing treatment liquid consists of rare earth metal salt, complexing agent, corrosion inhibitor, activator and water.

[0005] Furthermore, the rare earth metal salt is ammonium cerium nitrate or lanthanum nitrate.

[0006] Furthermore, the complexing agent is polydopamine.

[0007] Furthermore, the corrosion inhibitor is a mixture of Tris and Na2MoO4 with a mass ratio of 2:1 to 4:1.

[0008] Furthermore, the active agent is polyethylene glycol or phytic acid.

[0009] Furthermore, the components of the sealing treatment liquid include, by mass percentage, rare earth metal salt: 15-35%, complexing agent: 1-5%, corrosion inhibitor: 1-5%, activator: 0.5-2%, the balance is water, and the system pH is 8-9.

[0010] A surface sealing treatment method for oriented silicon steel coating for marine environment comprises the following steps: (1) Remove oil and rust from the surface of silicon steel; (2) Immerse the treated silicon steel in a sealing treatment liquid and perform sealing treatment at a certain temperature and time; (3) Remove the silicon steel from the closed treatment liquid, clean and dry it; (4) Continue to stay in the ammonia solution of 5-10% by mass fraction of polydopamine for a period of time, take it out, dip it in liquid photosensitive resin and then cure it under ultraviolet light to form a hydrophobic layer with a thickness of less than 5 μm.

[0011] Furthermore, the sealing treatment in step (2) is performed at a temperature of 40-80° C. and for a time of 10-30 minutes.

[0012] Furthermore, in step (4), the residence temperature in the polydopamine complexing agent is 30-50° C., and the residence time is 8-12 hours.

[0013] Furthermore, the main component of the liquid photosensitive resin is acrylated epoxy resin.

[0014] The advantages of the present invention are: The silicon steel surface coating (inorganic insulating coating, such as chromium-free phosphate coating) is sealed with rare earth metal nitrate solution (such as cerium salt, lanthanum salt, etc.). Rare earth metal ions will be adsorbed on the pore surface of the silicon steel surface coating. In an alkaline environment, the catechol, amino and other functional groups of polydopamine act as ligands to react with metal ions for coordination and complexation. At the same time, they also complex with metal ions in the silicon steel matrix, promoting the self-repair of the surface coating under the synergistic effect of the corrosion inhibitor. The catechol and amino groups in polydopamine form a strong adhesion interaction with the silicon steel substrate through multiple covalent and non-covalent interactions with metal ions. In addition, the acrylated epoxy resin in the liquid photosensitive resin contains abundant hydroxyl and carboxyl groups, and there are a large number of active sites available for reaction in its cured network structure, which is conducive to forming hydrogen bonds or covalent bonds with amino groups, phenolic hydroxyl groups, etc. in polydopamine, resulting in strong interactions, thereby improving the binding force. Under ultraviolet light, a nucleophilic addition reaction occurs between the epoxy group and carboxyl group in the photosensitive resin and the amino group of polydopamine, thereby achieving covalent connection between the two and obtaining a photocurable layer with very strong bonding force to the sealing layer and excellent hydrophobicity. DETAILED DESCRIPTION

[0015] The main method to improve the corrosion resistance of materials in marine environments is to improve the corrosion resistance of surface coatings. In principle, improving the hydrophobicity of the coating can further improve the corrosion resistance.

[0016] Therefore, the starting point of this patent is to take the conventional coating sealing treatment as a technical point of view, and to further improve the corrosion resistance of the coating by adding hydrophobic materials through UV curing of photosensitive resin.

[0017] The present invention provides a surface sealing treatment method for oriented silicon steel coating for marine environment, comprising the following steps: (1) The sealing treatment liquid is composed of rare earth metal salt, complexing agent, corrosion inhibitor, active agent and water. The rare earth metal salt is cerium ammonium nitrate (NH4)2Ce(NO3)6 or lanthanum nitrate, polydopamine is the complexing agent, tris(hydroxymethylaminomethane) Tris and Na2MoO4 (mass ratio is 2:1~4:1) are corrosion inhibitors, and polyethylene glycol or phytic acid is the active agent.

[0018] Mix the above substances in mass percentage: Rare earth metal salt: 15~35%, polydopamine complexing agent: 1~5%, Tris and Na2MoO4 corrosion inhibitors: 1~5%, polyethylene glycol or phytic acid activator 0.5~2%, the balance is water, and the system pH is 8-9.

[0019] (2) Perform routine treatment on the silicon steel surface to remove oil stains, rust, etc.; (3) Immerse the pretreated silicon steel parts in a sealing treatment liquid and perform sealing treatment at a certain temperature and time; wherein the sealing treatment temperature is 40-80°C and the time is 10-30 minutes; (4) Remove the silicon steel from the closed treatment liquid, clean and dry it; (5) Continue to stay in a 5-10% by mass fraction of polydopamine complexing agent ammonia aqueous solution (pH 9) at 30-50°C for 8-12 hours, take out, dip-coat with liquid photosensitive resin, and then cure under ultraviolet light to form a hydrophobic layer with a thickness of less than 5 μm.

[0020] Furthermore, the main component of the liquid photosensitive resin used is acrylated epoxy resin.

[0021] The photosensitive resins used in the following examples all have photoinitiators added, such as 355 photoinitiator triarylsulfonium hexafluoroantimonate commonly used in 3D printing. The raw material silicon steel used has a chromium-free phosphate coating on its surface.

[0022] In order to make the above features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description. The methods of the present invention are all conventional methods in the art unless otherwise specified.

[0023] Embodiment 1: (1) Prepare the sealing treatment solution: (NH4)2Ce(NO3)6: 15g, polydopamine: 2.5g, Tris and Na2MoO4 mass ratio of 2:1, corrosion inhibitor: 5g, polyethylene glycol: 1g, prepare into 100g aqueous solution, and control the pH to 8.5.

[0024] (2) Perform routine treatment on the silicon steel surface to remove oil stains, rust, etc.; (3) The pre-treated silicon steel area is 10cm 2 Immerse in the sealing treatment solution, control the temperature at 40℃, and the time for 30 minutes; (4) Remove the silicon steel from the closed treatment liquid, clean and dry it; (5) The film was then placed in a 10% by mass polydopamine complexing agent ammonia solution (pH 9) at 30 °C for 12 h, taken out, dipped in liquid photosensitive resin (acrylated epoxy resin, J-969, Qingdao Jinwanli Fine Chemical Co., Ltd.), and cured under ultraviolet light to form a hydrophobic layer with a thickness of 4 to 5 μm.

[0025] Embodiment 2: (1) Prepare the sealing treatment solution: (NH4)2Ce(NO3)6: 15g, polydopamine: 5g, Tris and Na2MoO4 mass ratio of 2:1, corrosion inhibitor: 5g, phytic acid: 1g, prepare into 100g aqueous solution, and control the pH to 9.

[0026] (2) Perform routine treatment on the silicon steel surface to remove oil stains, rust, etc.; (3) The pre-treated silicon steel area is 10cm 2 Immerse in the sealing treatment solution, control the temperature to 40℃, and the time is 10 minutes; (4) Remove the silicon steel from the sealing treatment liquid and clean and dry it.

[0027] (5) Continue to stay in a 5% by mass fraction of polydopamine in an ammonia solution (pH 9) at 30°C for 12 hours, take it out, dip-coat the surface with liquid photosensitive resin (acrylated epoxy resin), take it out and then cure it under ultraviolet light to form a hydrophobic layer with a thickness of 4 to 5 μm.

[0028] Embodiment 3: (1) Prepare the sealing treatment solution: (NH4)2Ce(NO3)6: 15g, polydopamine 2.5g, Tris and Na2MoO4 mass ratio of 2:1, corrosion inhibitor: 5g, phytic acid: 1g, prepare into 100g aqueous solution, and control the pH to 8.5.

[0029] (2) Perform routine treatment on the silicon steel surface to remove oil stains, rust, etc.; (3) The pre-treated silicon steel area is 10cm 2 Immerse in the sealing treatment solution, control the temperature to 40℃, and the time is 10 minutes; (4) Remove the silicon steel from the sealing treatment liquid and clean and dry it.

[0030] (5) Continue to stay in a 5% by mass fraction of polydopamine in an ammonia solution (pH 9) at 30°C for 12 hours, take it out, dip-coat the surface with liquid photosensitive resin (acrylated epoxy resin), take it out and then cure it under ultraviolet light to form a hydrophobic layer with a thickness of 4 to 5 μm.

[0031] Embodiment 4: (1) Prepare the sealing treatment solution: La(NO3)3: 15g, polydopamine: 2.5g, Tris and Na2MoO4 mass ratio of 2:1, corrosion inhibitor: 5g, polyethylene glycol: 1g, prepare into 100g aqueous solution, and control the pH to 8.5.

[0032] (2) Perform routine treatment on the silicon steel surface to remove oil stains, rust, etc.; (3) The pre-treated silicon steel area is 10cm 2 Immerse in the sealing treatment solution, control the temperature at 40℃, and the time for 30 minutes; (4) Remove the silicon steel from the closed treatment liquid, clean and dry it; (5) The film was then placed in a 10% by mass polydopamine complexing agent ammonia solution (pH 9) at 30 °C for 12 h, taken out, dipped in liquid photosensitive resin (acrylated epoxy resin, J-969, Qingdao Jinwanli Fine Chemical Co., Ltd.), and cured under ultraviolet light to form a hydrophobic layer with a thickness of 4 to 5 μm.

[0033] Comparative Example 1: The results of immersing the oriented silicon steel raw material with a chromium-free phosphate coating on the surface without sealing treatment and the silicon steel without a photocuring layer (without step 5) in Examples 1-4 of this case in a 3% mass fraction NaCl solution for 24×7 hours are shown in Table 1.

[0034] The oriented silicon steel coatings of Examples 1-4 were immersed in a 3% by mass NaCl solution for 24×7 hours. The results showed that the oriented silicon steel coatings for marine environments of the present invention had significantly better corrosion resistance after sealing treatment than the comparative examples, as shown in Table 2.

[0035] Table 1 Weight loss rate of silicon steel sealed with different coatings after immersion in 3% mass fraction NaCl solution for 24 × 7 hours Table 2 Weight loss rate of silicon steel after sealing treatment and then light curing in Example 1-4 after immersion in 3% mass fraction NaCl solution for 24×7 hours Comparative Example 2: (resin screening) (1) Prepare the sealing treatment solution: (NH4)2Ce(NO3)6: 15g, polydopamine: 2.5g, Tris and Na2MoO4 mass ratio of 2:1, corrosion inhibitor: 5g, polyethylene glycol: 1g, prepare into 100g aqueous solution, and control the pH to 8.5.

[0036] (2) Perform routine treatment on the silicon steel surface to remove oil stains, rust, etc.; (3) The pre-treated silicon steel area is 10cm 2 Immerse in the sealing treatment solution, control the temperature at 40℃, and the time for 30 minutes; (4) Remove the silicon steel from the closed treatment liquid, clean and dry it; (5) The samples were kept in a 10% by mass aqueous solution of polydopamine complexing agent (pH 9) at 30 °C for 12 h, taken out, and dipped in different liquid photosensitive resins (unsaturated polyester TM-191RS, Changzhou Tianma Group Co., Ltd.; polyurethane HD-100, Houding Chemical Co., Ltd., Changzhou, Jiangsu) and then cured under ultraviolet light to form a hydrophobic layer with a thickness of 4 to 5 μm.

[0037] Table 3 Wetting angles of different photocurable resins after curing and weight loss after immersion in 3% mass fraction NaCl solution for 24 × 7 hours The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A sealing treatment liquid for sealing the surface of oriented silicon steel coating, characterized in that: The closed treatment liquid consists of rare earth metal salt, complexing agent, corrosion inhibitor, activator and water.

2. The sealing treatment liquid according to claim 1, characterized in that: The rare earth metal salt is ammonium cerium nitrate or lanthanum nitrate.

3. The sealing treatment liquid according to claim 1, characterized in that: The complexing agent is polydopamine.

4. The sealing treatment liquid according to claim 1, characterized in that: The corrosion inhibitor is a mixture of Tris and Na2MoO4 with a mass ratio of 2:1~4:

1.

5. The sealing treatment liquid according to claim 1, characterized in that: The active agent is polyethylene glycol or phytic acid.

6. The sealing treatment liquid according to claim 1, characterized in that: The components of the sealing treatment liquid include, by mass percentage, rare earth metal salt: 15-35%, complexing agent: 1-5%, corrosion inhibitor: 1-5%, activator: 0.5-2%, and the balance is water. The system pH is 8-9.

7. A method for treating the surface of a oriented silicon steel coating for a marine environment using the closed treatment solution of claim 1, characterized in that: The following steps are involved: (1) Remove oil and rust from the surface of silicon steel; (2) Immerse the treated silicon steel in a sealing treatment liquid and perform sealing treatment at a certain temperature and time; (3) Remove the silicon steel from the closed treatment liquid, clean and dry it; (4) Continue to stay in the ammonia solution of 5-10% by mass fraction of polydopamine for a period of time, take it out, dip it in liquid photosensitive resin and then cure it under ultraviolet light to form a hydrophobic layer with a thickness of less than 5 μm.

8. The method according to claim 7, characterized in that The sealing treatment in step (2) is carried out at a temperature of 40-80°C and for a time of 10-30 minutes.

9. The method according to claim 7, characterized in that: In step (4), the residence temperature in the polydopamine complexing agent is 30-50° C., and the residence time is 8-12 hours.

10. The method according to claim 7, characterized in that The main component of liquid photosensitive resin is acrylated epoxy resin.

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