A polymer modified graphene doped cold spray zinc coating and a method of making the same

Abstract

The application discloses a polymer modified graphene doped cold-sprayed zinc coating and a preparation method thereof. The cold-sprayed zinc coating is composed of the following raw materials in percentage by mass: 5-10% of high-permeability solvent, 55-95% of zinc powder, 0.2-1% of modified polymer conductive resin, 0.5-1.5% of silane coupling agent, 5-15% of polymer epoxy resin, 3-7% of aluminum silver paste, 1-3% of flaky graphene paste, 1-3% of modified fumed silica and 1-3% of composite wax paste. The application solves the problems of low adhesion and cohesion, poor salt mist resistance of thin coating, and general mechanical performance of the existing product, and the coating is not easy to produce zinc salt in long-term outdoor or salt mist environment, thereby improving the coating appearance and secondary coating performance.

Description

Technical Field

[0001] This invention belongs to the field of anti-corrosion coating technology, specifically relating to a polymer-modified graphene-doped cold-spray zinc coating and its preparation method. Background Technology

[0002] Metal corrosion refers to the phenomenon where metals are damaged due to chemical reactions between their surface and the surrounding medium. It not only wastes resources and energy but also causes equipment damage and environmental pollution. Corrosion accidents can endanger personal safety and cause significant losses to the national economy. Therefore, metal components are coated with anti-corrosion protective coatings to resist corrosion and extend their service life. Currently, anti-corrosion protective coatings mainly include shielding coatings, passivating and corrosion-inhibiting coatings, and cathodic protection coatings based on their anti-corrosion principles. Cathodic protection coatings provide both cathodic protection and shielding against corrosion, exhibiting excellent anti-corrosion performance. They are currently high-performance primers in the field of heavy-duty anti-corrosion, mainly including various zinc-rich primers, cold-sprayed zinc (cold galvanizing), and hot-dip galvanizing (hot spraying zinc). Cold-sprayed zinc (cold galvanizing) is mainly composed of zinc powder, film-forming substances, solvents, and other auxiliary materials. Due to its extremely high zinc powder content and excellent cathodic protection effect, and the fact that it does not require energy-consuming and polluting high-temperature heat treatment, it has extremely high application value. However, due to the low content of film-forming substances, the current cold spray zinc coating has poor adhesion to the substrate, many pores in the coating, and corrosive media can easily penetrate the coating, leading to a large consumption of sacrificial anodes. Under salt spray conditions, a large amount of white zinc salt will be generated, which is not conducive to the appearance of the coating and secondary coating.

[0003] Chinese patent CN 106118176 A discloses a cold-spray zinc anti-corrosion coating, composed of the following raw material formulation components by mass percentage: 12-15 parts graphene oxide, 10-12 parts microcrystalline graphene, 5-6 parts polyvinyl chloride, 5-8 parts asphalt, 4-6 parts butyl acrylate, 3-5 parts bis(trifluoromethanesulfonyl)imide, 4-5 parts methyl methacrylate, 4-6 parts silica, 5-6 parts silica, 3-4 parts bentonite, 6-8 parts nano zinc powder, 5-6 parts nano silver powder, 3-4 parts nano copper powder, 3-5 parts nano aluminum powder, and 40-50 parts deionized water. However, the use of graphene material and a large amount of organic materials and non-zinc metal powders results in an excessively low content of zinc powder (the sacrificial anode) and an excessively high content of organic matter, leading to weak cathodic protection. Furthermore, the addition of large amounts of copper and silver powders makes the coating costly and hinders its large-scale application and promotion.

[0004] Chinese patent CN 103254716 A discloses an environmentally friendly, high-efficiency waterproof and anti-corrosion cold spray zinc coating and its preparation method. It uses nano-silica as a filling material for the pores of the coating. Although silica, as an inorganic material, has a certain effect of filling and sealing pores, it does not help the adhesion and cohesion of the coating.

[0005] Chinese patent CN 108948898 A discloses a low-surface-treatment cold-spray zinc coating and its preparation method. It uses graphene-modified acrylic resin to improve coating adhesion and density, nano-silica to increase coating density, and mixed alcohol solvents to increase penetration into corrosive substrates. However, acrylic resin does not possess strong anti-corrosion properties and is rarely used in primers. Furthermore, the nano-silica filler has limited effect on improving coating adhesion. Ultimately, the coating's salt spray resistance can only reach a maximum of approximately 1000 hours.

[0006] Chinese patent CN 116515373 B discloses a cold-sprayed zinc anti-corrosion primer, its preparation method, and its application. It employs a compounding scheme of several resins, exhibiting high anti-corrosion capabilities; an 85-micron thick coating can withstand 6000 hours of salt spray. However, due to the low overall resin content, the coating's adhesion is weak. Furthermore, because the coating lacks suitable means to initially shield against the penetration of corrosive media, its film-like rust prevention performance is poor. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a polymer-modified graphene-doped cold-spray zinc coating and its preparation method, which solves the problems of low adhesion and cohesion, poor salt spray resistance of thin coatings, and general mechanical properties of existing products. At the same time, the coating is less prone to zinc salt formation when exposed to outdoor or salt spray environments for a long time, thus improving the appearance and recoating performance of the coating.

[0008] To achieve the above objectives, the present invention provides a polymer-modified graphene-doped cold-spray zinc coating, which is composed of the following raw materials in the indicated mass percentages: 5-10% high-penetration solvent, 60-85% zinc powder, 0.2-1% modified polymer conductive resin, 0.5-1.5% silane coupling agent, 5-15% polymer epoxy resin, 3-7% aluminum silver paste, 1-3% sheet graphene slurry, 1-3% fumed silica, and 1-3% composite wax slurry.

[0009] Preferably, the high-permeability solvent is a mixture of ketone solvents, alkane solvents and alcohol solvents in a mass ratio of 5:3:2.

[0010] More preferably, the ketone solvent is one or more of acetone, cyclohexanone, and methyl ethyl ketone; the alkane solvent is one or more of n-hexane, n-heptane, and cyclohexane; and the alcohol solvent is one or more of ethanol, isopropanol, n-butanol, and isobutanol.

[0011] Preferably, the zinc powder is composed of spherical zinc powder and modified flake zinc powder in a mass ratio of 50-80:5-15.

[0012] More preferably, the particle size of the spherical zinc powder is 500-1000 mesh.

[0013] More preferably, the modified flake zinc powder is flake zinc powder with a flake diameter ratio of 50-150:1 modified with stearic acid.

[0014] More preferably, the modification method of the modified flaky zinc powder is to mix the flaky zinc powder with stearic acid and then grind them in a ball mill at 1300 rpm / min with a ball-to-powder ratio of 10:1 for 80 min, wherein the amount of stearic acid used is 3% of the mass of the flaky zinc powder.

[0015] Preferably, the modified polymer conductive resin is a polymer conductive resin modified with ethylene glycol and glycidyl ether; the polymer conductive resin is any one of perfluorosulfonic acid resin, sulfonated polyether ether ketone, and sulfonated polysulfone.

[0016] Preferably, the silane coupling agent is glycidyl ether oxypropyltrimethoxysilane (KH-560).

[0017] A further preferred embodiment is the modification method of the modified polymer conductive resin as follows: S1: Mix the polymer conductive resin with a solvent to prepare a solution with a mass concentration of 5-10%, add ethylene glycol and p-toluenesulfonic acid, and react at 80-140℃ for 6-12 hours to obtain the reaction solution. S2: Add glycidyl ether and alkaline catalyst to the reaction solution, and react at 70-100℃ for 8-16 hours to obtain modified polymer conductive resin.

[0018] More preferably, the solvent in step S1 is DMF or DMSO, and the mass ratio of the polymer conductive resin to ethylene glycol and p-toluenesulfonic acid is 100:60:5.

[0019] More preferably, in step S2, the amounts of glycidyl ether and alkaline catalyst are 99% and 1% of the reaction solution, respectively.

[0020] Furthermore, the alkaline catalyst is NaOH.

[0021] Preferably, the high molecular weight epoxy resin is composed of urethane-modified high molecular weight epoxy resin and polyolefin-modified linear macromolecular epoxy resin in a mass ratio of 3-10:2-5.

[0022] More preferably, the urethane-modified epoxy resin is an urethane-modified epoxy resin with a solid content of 45%, and the solvent is xylene and butanol in a mass ratio of 8:2; the urethane-modified epoxy resin with a solid content of 45% is EPOKEYTM 505-15.

[0023] More preferably, the polyolefin-modified linear macromolecular epoxy resin is a polyolefin-modified linear macromolecular epoxy resin with a solid content of 50%, and the solvent is cyclohexanone and malonic acid monomethyl ether in a mass ratio of 4:6.

[0024] More preferably, the modification method is as follows: S1 Premix: Melt 100 parts of linear bisphenol A type epoxy resin (E-12) in an oven at 120°C (about 1 hour), pour it into a high-speed mixer, add 10-15 parts of POE-g-MAH (maleic anhydride grafted polyolefin) particles and 0.5-1.0 parts of triphenylphosphine catalyst, and stir at 120°C and 800 r / min for 30 minutes to completely melt and disperse POE-g-MAH; S2: Polymerization: Cool to 100℃, add curing agent 4,4'-diaminodiphenyl sulfone (8-10 parts), and continue stirring for 20 minutes to obtain modified epoxy resin. S3: Dissolution: Add the modified epoxy resin to the mixed solvent and stir at low speed for 2-4 hours to obtain polyolefin-type modified linear macromolecular epoxy resin liquid.

[0025] Preferably, the sheet graphene slurry is a sheet graphene dispersion with a solid content of 10%, and the commercial model is GRF-FLGOD-04.

[0026] Preferably, the aluminum silver paste is a non-floating aluminum silver paste and / or a floating aluminum silver paste; the composite wax paste is a composite wax paste composed of polyethylene and polyamide in a mass ratio of 4:6.

[0027] More preferably, the mass ratio of the non-floating aluminum silver paste to the floating aluminum silver paste is 9:1 to 1:9.

[0028] Preferably, the fumed silica has a specific surface area of ​​100-200 m². 2 / g of hydrophobic fumed silica.

[0029] This invention also provides a method for preparing a polymer-modified graphene-doped cold-spray zinc coating, comprising the following steps: (1) Take the flake zinc powder, ball mill it, add stearic acid to modify it, and then mix the modified flake zinc powder with the ball zinc powder to obtain zinc powder; (2) Ethylene glycol and p-toluenesulfonic acid were added to the polymer conductive resin, and after the reaction was heated, glycidyl ether and alkaline catalyst were added to obtain the modified polymer conductive resin. (3) A highly permeable solvent is obtained by mixing ketone solvent, alkane solvent and alcohol solvent. Zinc powder, modified polymer proton conduction material and silane coupling agent are added while stirring, and a premixed slurry is obtained by stirring. (4) Take urethane-modified high molecular weight epoxy resin and polyolefin-modified linear macromolecular epoxy resin to obtain high molecular weight epoxy resin. (5) Polyethylene and polyamide are mixed at a mass ratio of 4:6 to obtain a composite wax slurry; (6) While stirring, add high molecular epoxy resin, aluminum silver paste, sheet graphene paste, fumed silica and composite wax paste to the premixed slurry, mix and filter to obtain cold spray zinc coating.

[0030] Preferably, the stirring speed in step (3) is 500-800 rpm and the stirring time is 15-30 min; the stirring speed in step (7) is 500-800 rpm and the stirring time is 5-10 min.

[0031] The beneficial effects of this invention are as follows: 1. By using sheet-like graphene in synergy with modified polymer conductive resin, a "proton-electron dual conductivity" mode is achieved, fundamentally blocking the anodic iron dissolution (Fe→Fe) that occurs during electrochemical corrosion. 2+ +2e - ) and cathodic reduction reactions (such as O2 + 2H2O + 4e) - →4OH - Simultaneously, the sheet-like graphene, combined with zinc powder, rapidly extracts or disperses electrons from the steel surface, preventing electron accumulation in the cathode region and reducing the rate of the cathode reduction reaction; the proton conductor guides the H generated by corrosion. + (Acidic environment) or OH - Directed migration in an alkaline environment prevents excessively high local ion concentrations from exacerbating corrosion, thus improving cohesion and corrosion resistance.

[0032] 2. By modifying flake zinc powder, flake graphene, and flake aluminum powder in aluminum silver paste, a multi-layered, flake-like, three-dimensional structure with a thickness ranging from 2 nm to 2 μm was constructed. Even in thin coating conditions (20-50 μm), the coating exhibits an extremely excellent shielding effect, cutting off the channels for the flow of corrosive media before corrosion occurs, making corrosion difficult to occur and persist. Simultaneously, the zinc powder treated with modified polymer conductive resin and silane coupling agent exhibits better adhesion, and the entire coating has better density, further improving corrosion resistance.

[0033] 3. Modified flake zinc powder, flake graphene, and flake aluminum powder in aluminum silver paste construct a multi-layered, three-dimensional, scaly structure, enhancing the coating's flexibility and mechanical strength, as well as its durability and longevity. Simultaneously, surface modification with silane coupling agents reduces "interfacial defects" between inorganic and organic materials, resulting in better powder dispersibility, water resistance, and functionality, ultimately improving the overall performance of the composite material. Furthermore, the highly penetrating solvent has low molecular steric hindrance and a surface tension below 20 mN / m, making it easier for the coating to wet the substrate and penetrate into the substrate's tiny crevices, resulting in stronger adhesion to the substrate and improved adhesion even after aging. Attached Figure Description

[0034] Figure 1 The image shows the corrosion protection properties of the cold-sprayed zinc coating prepared in Example 1.

[0035] Figure 2 The image shows the corrosion protection of the cold-sprayed zinc coating prepared in Comparative Example 1. Detailed Implementation

[0036] The technical solution of the present invention will be further explained and described below with reference to specific accompanying drawings and embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the contents of the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present invention without creative effort all fall within the scope of protection of the present invention.

[0037] In the following examples, the silane coupling agent is glycidyl ether oxypropyltrimethoxysilane, commercially available under the model name KH-560; The sheet graphene slurry is a sheet graphene dispersion with a solid content of 10%, and its commercial model is GRF-FLGOD-04. The 45% urethane-modified epoxy resin is obtained by dissolving the urethane-modified epoxy resin in a composite solvent composed of xylene and butanol in a mass ratio of 8:2, and mixing thoroughly. The polyolefin-modified linear macromolecular epoxy resin with a solid content of 50% is obtained by dissolving the polyolefin-modified linear macromolecular epoxy resin in a composite solvent composed of cyclohexanone and malonic acid monomethyl ether in a mass ratio of 4:6, and mixing them thoroughly. Modified flake zinc powder was prepared by high-energy ball milling using 5mm bearing steel balls in a horizontal stirred ball mill at a stirring speed of 1300 rpm / min, a ball-to-material ratio of 10:1, and a milling time of 80 min. 3% stearic acid was added as a modifier. The fumed silica is hydrophobic and typically has a specific surface area of ​​200 m². 2 / g; The composite wax paste is composed of polyethylene and polyamide in a mass ratio of 4:6.

[0038] Example 1 A cold-sprayed graphene-zinc coating is composed of the following raw materials by mass percentage: 7.3% high-penetration solvent, 73% zinc powder, 0.2% modified polymer conductive resin, 0.5% silane coupling agent, 12% polymer epoxy resin, 3% aluminum silver paste, 1% sheet graphene paste, 2% fumed silica, and 1% composite wax paste; The high-permeability solvent is composed of anhydrous acetone, anhydrous n-hexane and anhydrous ethanol in a mass ratio of 5:3:2; The zinc powder is composed of spherical zinc powder and modified flake zinc powder in a mass ratio of 68:5; The preparation method of the modified polymer conductive resin includes the following steps: S1: Dissolve perfluorosulfonic acid resin in DMSO to prepare a 5% (w / w) solution, add 60% ethylene glycol and 5% p-toluenesulfonic acid, heat to 80℃ and react for 12 hours to obtain the reaction solution; S2: Add 99% glycidyl ether and 1% alkaline catalyst to the reaction solution, react at 70°C for 16 hours, and then wash and dry with dichloromethane to obtain the modified polymer conductive resin. The high molecular weight epoxy resin with a solid content of 45% urethane modified high molecular weight epoxy resin and a polyolefin modified linear macromolecular epoxy resin with a solid content of 50% are composed of a mass ratio of 5:1. The aluminum silver paste is a non-floating aluminum silver paste with a particle size of 15 micrometers and a solid content of 60%. The preparation method includes the following steps: (1) Add high-penetration solvent, zinc powder, modified polymer conductive resin and silane coupling agent while stirring at 500 rpm, and continue stirring for 30 min to obtain premixed slurry; (2) While stirring the premixed slurry at a speed of 500 rpm, add the polymer epoxy resin, aluminum silver paste, sheet graphene slurry, fumed silica and composite wax slurry in sequence, continue stirring for 10 min, and then filter with an 80 mesh screen to obtain cold spray zinc coating.

[0039] Example 2 A cold-sprayed graphene-zinc coating is composed of the following raw materials by weight percentage: 7.8% high-penetration solvent, 68% zinc powder, 0.4% modified polymer conductive resin, 0.8% silane coupling agent, 11% polymer epoxy resin, 6% aluminum silver paste, 3% sheet graphene paste, 2% fumed silica, and 1% composite wax paste; The high-permeability solvent is composed of anhydrous cyclohexanone, anhydrous n-heptane and anhydrous n-butanol in a mass ratio of 5:3:2; The zinc powder is composed of spherical zinc powder and modified flake zinc powder in a mass ratio of 60:8; The preparation method of the modified polymer conductive resin is the same as in Example 1, except that the perfluorosulfonic acid resin is replaced with sulfonated polyether ether ketone. The high molecular weight epoxy resin is composed of a high molecular weight epoxy resin modified with 45% solid content of urethane and a polyolefin-modified linear macromolecular epoxy resin with 50% solid content in a mass ratio of 9:2. The aluminum silver paste is composed of non-floating aluminum silver paste and floating aluminum silver paste in a mass ratio of 9:1; The preparation method is the same as in Example 1, except that the stirring speed is changed to 600 rpm, the stirring time in step (1) is changed to 25 min, and the stirring time in step (2) is changed to 8 min.

[0040] Example 3 A cold-sprayed graphene-zinc coating is composed of the following raw materials by weight percentage: 7% high-penetration solvent, 69% zinc powder, 0.8% modified polymer conductive resin, 1.2% silane coupling agent, 9% polymer epoxy resin, 7% aluminum silver paste, 3% sheet graphene paste, 2% fumed silica, and 1% composite wax paste; The high-permeability solvent is composed of methyl ethyl ketone, cyclohexane and isopropanol in a mass ratio of 5:3:2; The zinc powder is composed of spherical zinc powder and modified flake zinc powder in a mass ratio of 50:15; The preparation method of the modified polymer conductive resin is the same as in Example 1, except that the perfluorosulfonic acid resin is replaced with sulfonated polysulfone. The high molecular weight epoxy resin is composed of a high molecular weight epoxy resin modified with 45% urethane solids and a polyolefin-modified linear macromolecular epoxy resin with 50% olefin solids in a mass ratio of 7:2. The aluminum silver paste is composed of non-floating aluminum silver paste and floating aluminum silver paste in a mass ratio of 1:1; The preparation method is the same as in Example 1, except that the stirring speed is changed to 700 rpm, the stirring time in step (1) is changed to 20 min, and the stirring time in step (2) is changed to 6 min.

[0041] Example 4 A cold-sprayed graphene-zinc coating is composed of the following raw materials by mass percentage: 5% high-penetration solvent, 83.3% zinc powder, 0.2% modified polymer conductive resin, 0.5% silane coupling agent, 5% polymer epoxy resin, 3% aluminum silver paste, 1% sheet graphene paste, 1% fumed silica, and 1% composite wax paste; The zinc powder is composed of spherical zinc powder and modified flake zinc powder in a mass ratio of 80:5; The high molecular weight epoxy resin is composed of a high molecular weight epoxy resin modified with 45% solid content of urethane and a polyolefin-modified linear macromolecular epoxy resin with 50% solid content in a mass ratio of 3:5. The aluminum silver paste is composed of non-floating aluminum silver paste and floating aluminum silver paste in a mass ratio of 1:9; The preparation method is the same as in Example 1, except that the stirring speed is changed to 800 rpm, the stirring time in step (1) is changed to 15 min, and the stirring time in step (2) is changed to 5 min.

[0042] Comparative Example 1 The formulation and preparation method are the same as in Example 1, except that the zinc powder is replaced with spherical zinc powder to prepare a cold-spray zinc coating.

[0043] Comparative Example 2 The formulation and preparation method are the same as in Example 1, except that the modified flake zinc powder in the zinc powder is replaced with an equal amount of unmodified flake zinc powder to prepare the cold-spray zinc coating.

[0044] Comparative Example 3 The formulation and preparation method are the same as in Example 1, except that the high-penetration solvent is replaced with an equal amount of xylene and butanol (volume ratio of 7:3) solution to prepare the cold-sprayed zinc coating.

[0045] Comparative Example 4 The formulation and preparation method are the same as in Example 1, except that the modified polymer conductive material is replaced with an equal amount of E12 epoxy resin to prepare the cold-sprayed zinc coating.

[0046] Comparative Example 5 The formulation and preparation method are the same as in Example 1, except that the modified polymer conductive material is not used, and the formulation is made up to 100% with a high-penetration solvent to prepare the cold-spray zinc coating.

[0047] Comparative Example 6 The formulation and preparation method are the same as in Example 1, except that the amount of modified polymer conductive material is changed to 1.2%, and the amount of high-penetration solvent is reduced by 1% to prepare cold-spray zinc coating.

[0048] Comparative Example 7 The formulation and preparation method are the same as in Example 1, except that the high molecular weight epoxy resin is replaced with a high molecular weight epoxy resin modified entirely with 45% solid content urethane, and a cold-sprayed zinc oxide coating is prepared.

[0049] Comparative Example 8 The formulation and preparation method are the same as in Example 1, except that the aluminum silver paste is omitted and the amount of high-penetration solvent is changed to 10.3% to prepare cold-sprayed zinc coating.

[0050] Comparative Example 9 A cold-spray zinc coating is composed of the following raw materials by weight percentage: 8% high-penetration solvent, 77% spherical zinc powder, 12% high-molecular epoxy resin, 2% fumed silica, and 1% composite wax paste; The high molecular weight epoxy resin is composed of a high molecular weight epoxy resin modified with 45% solid content of urethane and a polyolefin-modified linear macromolecular epoxy resin with 50% solid content in a mass ratio of 10:2. The preparation method involves adding a high-penetration solvent and spherical zinc powder while stirring at 500 rpm. After stirring for 30 minutes, high-molecular epoxy resin, modified fumed silica, and composite wax slurry are added in sequence. After stirring for another 15 minutes, the mixture is filtered to obtain a cold-sprayed zinc coating.

[0051] Comparative Example 10 A cold-spray zinc coating is composed of the following raw materials by weight percentage: 9% high-penetration solvent, 76% zinc powder, 12% high-molecular epoxy resin, 2% fumed silica, and 1% composite wax paste; The zinc powder is composed of spherical zinc powder and modified flake zinc powder in a mass ratio of 70:6; The high molecular weight epoxy resin is composed of a high molecular weight epoxy resin modified with 45% solid content of urethane and a polyolefin-modified linear macromolecular epoxy resin with 50% solid content in a mass ratio of 10:2. The preparation method involves adding a high-penetration solvent and zinc powder while stirring at 500 rpm. After stirring for 30 minutes, high-molecular epoxy resin, modified fumed silica, and composite wax slurry are added in sequence. After stirring for another 15 minutes, the mixture is filtered to obtain a cold-sprayed zinc coating.

[0052] Example 6 The cold-sprayed zinc coatings prepared in the above examples and comparative examples were applied to polished tinplate (0.2 mm thick) and sandblasted steel plates (steel plate thickness not less than 3 mm, used only for pull-off adhesion testing). After 7 days of air drying, the performance indicators of the coatings were tested. The coating thickness was 23 ± 3 micrometers on the tinplate and 40 micrometers on the sandblasted steel plate. The test methods and results of the performance indicators are shown in Table 1. The coatings prepared in the above examples and comparative examples were applied to Q215 steel plates and allowed to air dry for 7 days. Following GB / T 1771 requirements, the plates were then subjected to a salt spray test in a 5% neutral sodium chloride solution at an ambient temperature of (35±2)℃. The results are shown in Table 2. Table 1 Performance Indicators of Cold-Sprayed Zinc-Alkene Coating

[0053] Table 2 Salt spray resistance of cold-sprayed zinc coating

[0054] Comparative Example 9 improved the coating's flexibility and substrate adhesion by increasing the proportion of high-molecular-weight epoxy resin and using a highly penetrating solvent, resulting in a significant improvement in cross-cut adhesion and recoil performance. However, the coating's corrosion resistance and salt spray resistance did not show significant improvement. When some flake zinc powder was added to the formulation, as in Comparative Example 10, the coating's salt spray resistance was significantly improved. This is because the introduced flake zinc powder, in addition to cathodic protection, also provided a certain degree of flake shielding, slowing down the penetration of corrosive media.

[0055] In Examples 1-3, the "proton-electron dual conductivity" system constructed from polymer conductive materials, zinc powder, and graphene significantly improved the coating's salt spray resistance. Combined with the shielding effect created by the tightly packed flake structure of sheet zinc powder, aluminum silver paste, and sheet graphene, and the surface modification of the zinc powder by coupling agents and polymer conductive materials, the coating became denser and had stronger adhesion. Therefore, the coating's salt spray resistance, especially the thin film's salt spray resistance, reached a new level. Furthermore, the sheet zinc powder, aluminum silver paste, and especially the sheet graphene, further enhanced the coating's flexibility and mechanical properties. Example 1 outperformed the comparative example in all performance aspects, particularly in thin film salt spray resistance and pull-off adhesion. Example 2 increased the proportion of functional materials, further improving overall performance; the salt spray resistance of the normal thickness coating was three times that of Comparative Example 1, and the salt spray resistance of the thin film coating was six times that of Comparative Example 1. Recoil resistance and pull-off adhesion were also improved by approximately 100%.

[0056] The results are as follows Figure 1-2 As shown, the cold-sprayed zinc coating prepared in Example 1, when applied to Q235 steel and dried at room temperature for 7 days, was then sprayed with a 5% neutral sodium chloride solution according to GB / T 1771 requirements. The test was conducted for 500 hours in an environment with an internal temperature of (35±2)℃. No rust or blistering was observed, and no rust spread was observed at the marked areas. In contrast, the cold-sprayed zinc coating prepared in Comparative Example 1, after the same treatment, exhibited rust and blistering, with rust spreading 0.6 mm at the marked areas. This indicates that the cold-sprayed zinc coating prepared in Example 1 provided excellent anti-corrosion performance.

Claims

1. A polymer-modified graphene-doped cold-spray zinc coating, characterized in that: It is composed of the following raw materials in the following mass percentages: 5-10% high-penetration solvent, 55-95% zinc powder, 0.2-1% modified polymer conductive resin, 0.5-1.5% silane coupling agent, 5-15% polymer epoxy resin, 3-7% aluminum silver paste, 1-3% sheet graphene paste, 1-3% fumed silica, and 1-3% composite wax paste; The high-permeability solvent is composed of a mixture of ketone solvents, alkane solvents, and alcohol solvents in a mass ratio of 5:3:2; The zinc powder is composed of spherical zinc powder and modified flake zinc powder in a mass ratio of 50-80:5-15. The modified flake zinc powder is flake zinc powder with an aspect ratio of 50-150:1 that has been modified with stearic acid. The modified polymer conductive resin is a polymer conductive resin modified with ethylene glycol and glycidyl ether; the polymer conductive resin is any one of perfluorosulfonic acid resin, sulfonated polyether ether ketone and sulfonated polysulfone. The high-molecular-weight epoxy resin is composed of urethane-modified high-molecular-weight epoxy resin and polyolefin-modified linear macromolecular-weight epoxy resin in a mass ratio of 3-10:2-5. The urethane-modified high-molecular-weight epoxy resin is of the type EPOKEY. TM 505-15, the polyolefin-modified linear macromolecular epoxy resin is a polyolefin-modified linear macromolecular epoxy resin with a solid content of 50%, and the solvent is cyclohexanone and propylene glycol monomethyl ether, with a mass ratio of 4:

6. The modification method is as follows: S1 Premixing: 100 parts of linear bisphenol A type epoxy resin E-12 are melted in an oven at 120℃, poured into a high-speed mixer, 10-15 parts of POE-g-MAH particles and 0.5-1.0 parts of triphenylphosphine catalyst are added, and the mixture is stirred at 120℃ and 800 r / min for 30 min to completely melt and disperse POE-g-MAH; S2: Polymerization: Cool to 100℃, add 8-10 parts of curing agent 4,4'-diaminodiphenyl sulfone, and continue stirring for 20 minutes to obtain modified epoxy resin; S3 Dissolution: Add the modified epoxy resin to the mixed solvent and stir at low speed for 2-4 hours to obtain a polyolefin-modified linear macromolecular epoxy resin solution.

2. The polymer-modified graphene-doped cold-spray zinc coating according to claim 1, characterized in that: The aluminum silver paste is a non-floating aluminum silver paste and / or a floating aluminum silver paste; the composite wax paste is a composite wax paste composed of polyethylene wax and polyamide wax in a mass ratio of 4:

6.

3. The polymer-modified graphene-doped cold-spray zinc coating according to claim 1, characterized in that: The fumed silica has a specific surface area of ​​100-200 m². 2 / g of hydrophobic fumed silica.

4. A method for preparing a polymer-modified graphene-doped cold-spray zinc coating as described in any one of claims 1-3, characterized in that: Includes the following steps: (1) Take the flake zinc powder, ball mill it, add stearic acid to modify it, and then mix the modified flake zinc powder with the ball zinc powder to obtain zinc powder; (2) Ethylene glycol and p-toluenesulfonic acid were added to the polymer conductive resin, and after the reaction was heated, glycidyl ether and alkaline catalyst were added to obtain the modified polymer conductive resin. (3) A high-penetration solvent is obtained by mixing ketone solvent, alkane solvent and alcohol solvent. Zinc powder, modified polymer conductive resin and silane coupling agent are added while stirring, and a premixed slurry is obtained by stirring. (4) Take urethane-modified high molecular weight epoxy resin and polyolefin-modified linear macromolecular epoxy resin to obtain high molecular weight epoxy resin. (5) Polyethylene wax and polyamide wax are mixed at a mass ratio of 4:6 to obtain a composite wax slurry; (6) While stirring, add high molecular epoxy resin, aluminum silver paste, sheet graphene paste, fumed silica and composite wax paste to the premixed slurry, mix and filter to obtain cold spray zinc coating.

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