A graphene-modified conductive corrosion-resistant coating on a magnesium alloy surface and a preparation method thereof

Abstract

The present invention belongs to the technical field of metal protection, and particularly relates to a graphene-modified conductive corrosion-resistant coating on the surface of a magnesium alloy and a preparation method thereof. The coating comprises a bottom layer and a surface layer, wherein the bottom layer is a graphene-modified polypyrrole-silane layer, and the surface layer is a copper-graphene layer. The preparation method of the graphene-modified polypyrrole-silane layer comprises the following steps: depositing the bottom layer on the surface of the magnesium alloy by an electrochemical method, wherein the electrolyte of the electrochemical method is a mixture of pyrrole, graphene, a dispersant, and a silane coupling agent solution; and curing the copper-graphene coating on the bottom layer by coating, wherein the copper-graphene coating comprises the following components in parts by weight: 48-60% copper, 0.5-1% graphene, 1-5% epoxy resin, 35-45% organic solvent, 0.5-1.5% curing agent, and 0.5-1% functional additive. The present invention simultaneously improves electrical conductivity and corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal protection, and in particular relates to a graphene-modified conductive corrosion-resistant coating on the surface of a magnesium alloy and a preparation method thereof. Background Art

[0002] As the lightest metal structural material, magnesium alloy has the advantages of low density, high specific strength and specific stiffness, easy cutting, good electrical and thermal conductivity, excellent damping and shock absorption, electromagnetic shielding, and easy recycling. It is now widely used in the aerospace industry, such as aircraft and missile skins and cabins, aircraft wall panels, satellites, spacecraft and other load-bearing components.

[0003] With the increasing demand for lightweighting in key sectors such as aerospace and military equipment, and rail transportation, the application of magnesium alloys in these areas is expected to exceed 3 million tons in the next 5-10 years. The use of magnesium alloys in components of spacecraft and satellites can withstand the unique environment of space operations, such as temperature extremes caused by aerodynamic heating, ozone erosion, short-wave electromagnetic radiation, high-energy particles such as electrons and protons, and the impact of small meteorites.

[0004] Magnesium-aluminum alloys are typically composed of magnesium and aluminum, offering low density, high strength, and excellent mechanical properties. Magnesium-aluminum alloys typically have lower density than pure aluminum but higher strength, good corrosion resistance, and good thermal conductivity. They also exhibit good plasticity, making them suitable for various processing techniques such as casting, forging, and rolling. Magnesium-aluminum alloys are widely used in aerospace, automotive, electronic equipment, and sports equipment, as they provide lightweight and high-strength design solutions.

[0005] However, there is still a huge gap between the application potential of magnesium alloys and reality. The corrosion resistance of magnesium alloys has become a bottleneck hindering the large-scale industrial application of magnesium alloys. Magnesium is very active in metallic properties, has a low potential at room temperature, is easily corroded, and is extremely easy to oxidize. The magnesium oxide film spontaneously formed on its surface is loose and porous and easily dissolves in the atmospheric environment or corrosive media and loses its structural integrity, resulting in its failure during service due to a decrease in mechanical support. In some specific occasions, magnesium alloy parts are not only required to have excellent corrosion resistance, but also excellent electrical conductivity to achieve electromagnetic shielding or electromagnetic compatibility. Magnesium alloys themselves cannot achieve high conductivity and high corrosion resistance. Therefore, magnesium alloys need to be surface modified to improve their corrosion resistance.

[0006] Common conductive corrosion protection surface treatment technologies for magnesium alloys currently include chemical oxidation and nickel plating. Through chemical or electrochemical corrosion protection, a refractory film composed of oxides, chromides, phosphides, or other compounds is formed on the surface of the magnesium alloy. Currently, the chemical conversion processes used for magnesium alloys primarily include chromate, phosphate / permanganate, and stannate processes. Chemical conversion coatings offer excellent conductivity and superior corrosion resistance compared to the magnesium alloy substrate. However, due to their thinness and softness, these coatings on magnesium alloys still exhibit relatively poor corrosion resistance, typically with a salt spray resistance of less than 24 hours. Therefore, they are rarely used alone, except as a base coating for coatings and as intermediate process protection. Nickel plating on magnesium alloys primarily involves depositing a nickel layer (such as Ni-P) on the surface through an electroless plating process. This process offers advantages such as high gloss, electrical and thermal conductivity, excellent corrosion resistance, and high hardness, and has been widely used. However, the high density of the nickel coating compromises the lightweight advantages of magnesium alloys and makes coating complex structures such as deep pores and sharp corners difficult. Therefore, new surface coating technologies are needed that combine lightweighting, high conductivity, and high corrosion resistance for magnesium alloys. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a graphene-modified conductive corrosion-resistant coating on the surface of a magnesium alloy and a preparation method thereof, while improving the conductivity and corrosion resistance.

[0008] An embodiment of the present invention provides a graphene-modified conductive corrosion-resistant coating on a magnesium alloy surface, comprising a bottom layer and a surface layer, wherein the bottom layer is a graphene-modified polypyrrole-silane layer, and the surface layer is a copper-graphene layer;

[0009] The preparation method of the graphene-modified polypyrrole-silane layer is as follows: depositing a bottom layer on the surface of a magnesium alloy by an electrochemical method, wherein the electrolyte of the electrochemical method is a mixture of pyrrole, graphene, a dispersant, and a silane coupling agent solution, wherein the pyrrole concentration in the electrolyte is 0.1-0.3 mol / L, the graphene concentration is 0.15-1.5 mol / L, the dispersant concentration is 0.1-0.2 mol / L, and the solvent in the silane coupling agent solution is a mixture of water and methanol, wherein the volume ratio of water to methanol is 8-9:1-2, and the volume fraction of the silane coupling agent is 5-10%.

[0010] The copper-graphene layer is obtained by coating and curing a copper-graphene coating on a base layer. The copper-graphene coating comprises the following components by weight: 48-60% copper, 0.5-1% graphene, 1-5% epoxy resin, 35-45% organic solvent, 0.5-1.5% curing agent, and 0.5-1% functional additive. The copper is present in the form of copper powder, and the copper powder has a particle size of 0.1-20 μm, or a mixture of multiple particle sizes within the 0.1-20 μm particle size range, preferably a mixture of particles of 5-10 μm and 15-20 μm.

[0011] Optionally, the thickness of the bottom layer is 5-20 μm, and the thickness of the surface layer is 20-120 μm.

[0012] Optionally, the electrolyte further includes sodium salicylate.

[0013] Optionally, the dispersant is sodium dodecylbenzenesulfonate with a concentration of 0.1-0.2 mol / L; the silane coupling agent is at least one selected from KH550, KH560, and KH570, and the solvent of the silane coupling agent solution is a mixture of water and methanol.

[0014] Optionally, the epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0015] Optionally, the organic solvent is selected from at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether, propylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol methyl ether, diethylene glycol ethyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, and diethylene glycol butyl ether.

[0016] Optionally, the curing agent is selected from at least one of 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole.

[0017] Optionally, the functional auxiliary agent is selected from at least one of a silane coupling agent, a titanate coupling agent and an aluminate coupling agent.

[0018] The embodiment of the present invention provides a method for preparing the graphene-modified conductive corrosion-resistant coating on the surface of the magnesium alloy, which comprises first depositing a base layer on the surface of the magnesium alloy and then depositing a surface layer on the surface of the base layer;

[0019] The bottom layer is a graphene-modified polypyrrole-silane layer, and the preparation method of the graphene-modified polypyrrole-silane layer is to deposit the bottom layer on the surface of the magnesium alloy by an electrochemical method, wherein the electrolyte of the electrochemical method is a mixture of pyrrole, graphene, a dispersant, and a silane coupling agent solution, and the pyrrole concentration in the electrolyte is 0.1-0.3 mol / L, and the graphene concentration is 0.15-1.5 mol / L;

[0020] The surface layer is a copper-graphene layer, which is obtained by curing a copper-graphene coating on a bottom layer by coating. The copper-graphene coating includes the following components by weight: 48-60% copper, 0.5-1% graphene, 1-5% epoxy resin, 35-45% organic solvent, 0.5-1.5% curing agent, and 0.5-1% functional additive.

[0021] Alternatively, the electrochemical method is electrochemical cyclic voltammetry (using a three-electrode system) with a scanning potential range of -0.5 to 2 V.SCE , the scanning rate is 5~25mV / s, the scanning cycle is 5~20 times; the curing temperature after coating is 20~120℃, and the curing time is 0.5~24h.

[0022] The magnesium alloy is polished, degreased, deoiled and cleaned before the base layer is deposited.

[0023] The present invention has the beneficial effect of using polypyrrole, a conductive and corrosion-resistant polymer, to form a coating with other materials, providing additional performance advantages. Polypyrrole exhibits excellent conductivity, corrosion resistance, and wear resistance, as well as high chemical stability and high-temperature resistance. However, polypyrrole coatings lack the corrosion resistance required for long-term corrosion protection of magnesium alloys.

[0024] The graphene-modified conductive corrosion-resistant coating of the present invention has a composite structure, consisting of a base layer and a surface layer. The base layer uses a conductive polymer, and graphene and silane are designed to optimize and modify the base layer. Graphene exhibits excellent high conductivity and corrosion resistance, enhancing the long-term corrosion resistance of the base layer. Silane modification, on the other hand, forms an interface layer between the magnesium alloy and the resin, promoting group reactions at the interface. This enhances the bonding between the magnesium alloy and the resin by transferring stress, optimizes and improves the surface interface state, prevents the reaction and infiltration of impurities, and improves the corrosion resistance of the magnesium alloy coating.

[0025] In terms of the surface layer, metallic copper with excellent conductivity is used as the main conductor. On the one hand, by mixing copper powder under this particle size (especially the mixture of copper powders of different particle sizes), the density of the conductive layer is improved and its conductivity is enhanced; on the other hand, the surface layer is modified by graphene, and graphene is filled between the copper powder to further improve the conductivity and long-term corrosion resistance of the surface layer, thereby achieving high conductivity and high corrosion resistance of the overall coating; at the same time, adding functional additives such as alkane coupling agent, titanate coupling agent and aluminate coupling agent to the surface layer slurry can improve the bonding strength and corrosion resistance of the surface layer.

[0026] The graphene-modified conductive corrosion-resistant coating of this invention combines lightweight, high conductivity, and high corrosion resistance. Compared to magnesium alloy conductive oxidation (chemical oxidation) coatings, this coating offers significant corrosion resistance advantages. While magnesium alloy conductive oxidation coatings typically withstand salt spray for less than 24 hours, this coating offers a salt spray resistance of 96 hours or more. Compared to nickel plating on magnesium alloys, this coating boasts a density only one-third that of nickel plating, offering significant advantages in weight reduction.

[0027] The graphene-modified conductive corrosion-resistant coating of the present invention has a simple process and is easy to operate, and is very suitable for use as a conductive corrosion-resistant coating on the surface of magnesium alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is a SEM photograph of the graphene-modified polypyrrole-silane layer, i.e., the bottom layer, in Example 1 of the present invention.

[0029] Figure 2 This is a SEM photograph of the surface layer (copper-graphene layer) of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to specific embodiments in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0031] Example 1

[0032] Step 1: Take a magnesium alloy sheet with a size of 100mm*100mm*5mm, polish it with sandpaper, and then degrease it. Then, ultrasonically clean the magnesium alloy sheet with deionized water and anhydrous ethanol in sequence, blow dry it, and set it aside.

[0033] Step 2: Take water and methanol in proportion and mix them evenly, add silane coupling agent KH550 to the mixed solution, and mix again to obtain a silane coupling agent solution, wherein the volume ratio of water to methanol is 9:1 and the volume fraction of the silane coupling agent is 5%;

[0034] Sodium salicylate is added to the silane coupling agent solution and mixed uniformly, and then pyrrole, graphene and sodium dodecylbenzenesulfonate are added to obtain an electrolyte containing pyrrole and graphene, wherein the electrolyte has a pyrrole concentration of 0.15 mol / L, a sodium dodecylbenzenesulfonate concentration of 0.1 mol / L, a graphene concentration of 0.15 mol / L, and a sodium salicylate concentration of 0.15 mol / L;

[0035] Step 3: Based on the above electrolyte, a three-electrode system is used to deposit a graphene-modified polypyrrole-silane bottom layer on the magnesium alloy surface by electrochemical cyclic voltammetry, wherein the scanning potential range is -0.5 to 2 VSCE, the scanning rate is 5 mV / s, and the scanning cycle is 15 times;

[0036] Step 4: After completion, the magnesium alloy sheet is repeatedly rinsed with deionized water, placed in a drying oven, and dried at 50° C. for 5 hours to obtain a graphene-modified polypyrrole-silane bottom layer of about 15 μm on the magnesium alloy sheet.

[0037] Step 5: Copper powder, graphene, bisphenol A epoxy resin, propylene glycol methyl ether (PMGE) solvent, 2-ethyl-4-methylimidazole (2-ethyl-4-methylimidazole) curing agent, and KH550 (silane coupling agent) functional additive were weighed, dissolved, and stirred in a mass ratio of 55:0.5:1.5:42:0.5:0.5 to prepare a conductive coating containing conductive copper powder with a particle size of 15-20 μm. A 50-μm-thick conductive coating was sprayed onto the treated magnesium alloy substrate. The magnesium alloy was then cured in a 130°C drying oven for 0.3 h. Upon completion of the curing process, a graphene-modified conductive, corrosion-resistant coating was formed on the magnesium alloy surface.

[0038] The magnesium alloy conductive corrosion-resistant coating obtained in this example has a square resistance of 1.1Ω / sq and is salt spray resistant for 108 hours.

[0039] Example 2

[0040] A magnesium alloy sheet with a size of 100 mm*100 mm*5 mm was taken, and the magnesium alloy sheet was polished with sandpaper and then degreased. The magnesium alloy sheet was ultrasonically cleaned with deionized water and anhydrous ethanol in sequence, and then dried for use.

[0041] Water and methanol are taken in proportion and mixed evenly, silane coupling agent KH550 is added to the mixed solution, and mixed evenly again to obtain a silane coupling agent solution, wherein the volume ratio of water to methanol is 8:2, and the volume fraction of the silane coupling agent is 10%;

[0042] Sodium salicylate is added to the silane coupling agent solution and mixed uniformly, and then pyrrole, graphene and sodium dodecylbenzenesulfonate are added to obtain an electrolyte containing pyrrole and graphene, wherein the electrolyte has a pyrrole concentration of 0.2 mol / L, a sodium dodecylbenzenesulfonate concentration of 0.15 mol / L, a graphene concentration of 0.1 mol / L, and a sodium salicylate concentration of 0.15 mol / L;

[0043] Based on the above electrolyte, a graphene-modified polypyrrole-silane underlayer was deposited on the magnesium alloy surface by electrochemical cyclic voltammetry using a three-electrode system. The scanning potential range was -0.5 to 2 VSCE, the scanning rate was 10 mV / s, and the scanning cycle was 20 times.

[0044] After completion, the magnesium alloy sheet was repeatedly rinsed with deionized water, placed in a drying oven, and dried at 50° C. for 5 h to obtain a graphene-modified polypyrrole-silane bottom layer of about 18 μm on the magnesium alloy sheet.

[0045] Copper powder, graphene, phenolic epoxy resin, propylene glycol methyl ether acetate solvent, 2-phenyl-4-methylimidazole curing agent, and titanate coupling agent (functional additive) were weighed, dissolved, and stirred in the order of 48:1:3.5:45:1:1 to prepare a conductive coating containing conductive copper powder with a particle size of 15-20 μm. The conductive coating was then sprayed onto the treated magnesium alloy substrate to a thickness of 80 μm. The magnesium alloy was then cured in a drying oven at 120°C for 0.5 h. Upon completion of the curing process, a graphene-modified conductive, corrosion-resistant coating formed on the magnesium alloy surface.

[0046] The magnesium alloy conductive corrosion-resistant coating obtained in this example has a square resistance of 1.5Ω / sq and is salt spray resistant for 96 hours.

[0047] Example 3

[0048] A magnesium alloy sheet with a size of 100 mm*100 mm*5 mm was taken, and the magnesium alloy substrate was polished with sandpaper and then degreased. The magnesium alloy sheet was ultrasonically cleaned with deionized water and anhydrous ethanol in sequence, and then dried for use.

[0049] Water and methanol are taken in proportion and mixed evenly, silane coupling agent KH550 is added to the mixed solution, and mixed evenly again to obtain a silane coupling agent solution, wherein the volume ratio of water to methanol is 8:2, and the volume fraction of the silane coupling agent is 10%;

[0050] Sodium salicylate is added to the silane coupling agent solution and mixed uniformly, and then pyrrole, graphene and sodium dodecylbenzenesulfonate are added to obtain an electrolyte containing pyrrole and graphene, wherein the electrolyte has a pyrrole concentration of 0.2 mol / L, a sodium dodecylbenzenesulfonate concentration of 0.2 mol / L, a graphene concentration of 0.35 mol / L, and a sodium salicylate concentration of 0.25 mol / L;

[0051] Based on the above electrolyte, a graphene-modified polypyrrole-silane underlayer was deposited on the magnesium alloy surface by electrochemical cyclic voltammetry using a three-electrode system. The scanning potential range was -0.5 to 2 VSCE, the scanning rate was 15 mV / s, and the scanning cycle was 10 times.

[0052] After completion, the magnesium alloy sheet was repeatedly rinsed with deionized water, placed in a drying oven, and dried at 50° C. for 5 h to obtain a graphene-modified polypyrrole-silane bottom layer of about 20 μm on the magnesium alloy sheet.

[0053] Copper powder, graphene, phenolic epoxy resin, propylene glycol methyl ether acetate solvent, 2-phenyl-4-methylimidazole curing agent, and titanate coupling agent (functional additive) were weighed, dissolved, and stirred in a mass ratio of 60:0.5:2.5:35:1.5:0.5 to prepare a conductive coating containing conductive copper powder. A 100-μm-thick coating was sprayed onto the treated magnesium alloy substrate. The copper powder particle sizes were 5-10 μm and 15-20 μm, respectively, with a mass ratio of 1:3. The magnesium alloy was then cured in a 120°C drying oven for 0.5 h. Upon completion of curing, a graphene-modified conductive, corrosion-resistant coating formed on the magnesium alloy surface.

[0054] The magnesium alloy conductive corrosion-resistant coating obtained in this example has a square resistance of 0.8Ω / sq and is salt spray resistant for 108 hours.

[0055] Comparative Example 1

[0056] The remaining components and process steps are the same as those in Example 1, except that the electrolyte in step 2 does not contain graphene.

[0057] The magnesium alloy conductive corrosion-resistant coating obtained in this comparative example has a square resistance of 4.5Ω / sq and is salt spray resistant for 48 hours.

[0058] Comparative Example 2

[0059] The remaining components and process steps are the same as those in Example 1, except that the electrolyte in step 2 does not contain a silane coupling agent.

[0060] The magnesium alloy conductive corrosion-resistant coating obtained in this comparative example has a square resistance of 1.0 Ω / sq and is salt spray resistant for 48 hours.

[0061] Comparative Example 3

[0062] The remaining ingredients and process steps are the same as those in Example 1, except that the conductive coating in step 5 does not contain graphene.

[0063] The magnesium alloy conductive corrosion-resistant coating obtained in this comparative example has a square resistance of 3.9Ω / sq and is salt spray resistant for 72 hours.

[0064] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0065] The one or more embodiments of this application are intended to encompass all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application should be included in the scope of protection of this application.

Claims

1. A graphene-modified conductive corrosion-resistant coating on a magnesium alloy surface, characterized in that: It comprises a bottom layer and a surface layer, wherein the bottom layer is a graphene-modified polypyrrole-silane layer, and the surface layer is a copper-graphene layer; The preparation method of the graphene-modified polypyrrole-silane layer is to deposit a bottom layer on the surface of the magnesium alloy by an electrochemical method, wherein the electrolyte of the electrochemical method is a mixture of pyrrole, graphene, a dispersant, and a silane coupling agent solution, wherein the pyrrole concentration in the electrolyte is 0.1-0.3 mol / L and the graphene concentration is 0.15-1.5 mol / L; The copper-graphene layer is obtained by curing a copper-graphene coating on a bottom layer by coating, wherein the copper-graphene coating comprises the following components in parts by weight: 48-60% copper, 0.5-1% graphene, 1-5% epoxy resin, 35-45% organic solvent, 0.5-1.5% curing agent, and 0.5-1% functional additive; The copper exists in the form of copper powder, and the particle size of the copper powder is 0.1 to 20 μm.

2. The graphene-modified conductive corrosion-resistant coating on the surface of the magnesium alloy according to claim 1, characterized in that: The thickness of the bottom layer is 5-20 μm, and the thickness of the surface layer is 20-120 μm.

3. The graphene-modified conductive corrosion-resistant coating on the surface of the magnesium alloy according to claim 1, characterized in that: The electrolyte also includes sodium salicylate.

4. The graphene-modified conductive corrosion-resistant coating on the surface of the magnesium alloy according to claim 1, wherein: The dispersant is sodium dodecylbenzenesulfonate, the silane coupling agent is at least one selected from KH550, KH560, and KH570, and the solvent of the silane coupling agent solution is a mixture of water and methanol.

5. The graphene-modified conductive corrosion-resistant coating on the surface of a magnesium alloy according to any one of claims 1 to 4, characterized in that: The epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin.

6. The graphene-modified conductive corrosion-resistant coating on the surface of a magnesium alloy according to any one of claims 1 to 4, characterized in that: The organic solvent is selected from at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether, propylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol methyl ether, diethylene glycol ethyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, and diethylene glycol butyl ether.

7. The graphene-modified conductive corrosion-resistant coating on the surface of a magnesium alloy according to any one of claims 1 to 4, characterized in that: The curing agent is selected from at least one of 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole.

8. The graphene-modified conductive corrosion-resistant coating on the surface of a magnesium alloy according to any one of claims 1 to 4, characterized in that: The functional auxiliary agent is selected from at least one of a silane coupling agent, a titanate coupling agent and an aluminate coupling agent.

9. A method for preparing a graphene-modified conductive corrosion-resistant coating on a magnesium alloy surface according to any one of claims 1 to 8, characterized in that: A base layer is first deposited on the surface of the magnesium alloy, and then a surface layer is deposited on the surface of the base layer; The bottom layer is a graphene-modified polypyrrole-silane layer, and the preparation method of the graphene-modified polypyrrole-silane layer is to deposit the bottom layer on the surface of the magnesium alloy by an electrochemical method, wherein the electrolyte of the electrochemical method is a mixture of pyrrole, graphene, a dispersant, and a silane coupling agent solution, and the pyrrole concentration in the electrolyte is 0.1-0.3 mol / L, and the graphene concentration is 0.15-1.5 mol / L; The surface layer is a copper-graphene layer, which is obtained by curing a copper-graphene coating on a bottom layer by coating. The copper-graphene coating includes the following components by weight: 48-60% copper, 0.5-1% graphene, 1-5% epoxy resin, 35-45% organic solvent, 0.5-1.5% curing agent, and 0.5-1% functional additive.

10. The preparation method according to claim 9, wherein The electrochemical method was electrochemical cyclic voltammetry with a scanning potential range of -0.5 to 2 V. SCE , the scanning rate is 5~25mV / s, the scanning cycle is 5~20 times; the curing temperature after coating is 20~120℃, and the curing time is 0.5~24h.

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