Composite anti-corrosion coating suitable for catenary parts and preparation method of composite anti-corrosion coating

Abstract

The invention discloses a composite anti-corrosion coating suitable for a catenary part and a preparation method thereof.The method comprises the steps that electrolyte is prepared, the catenary part is placed in the electrolyte to be subjected to micro-arc oxidation treatment, and therefore a micro-arc oxidation layer is formed on the surface of the catenary part; s2, preparing functional layer coating liquid, then spraying the functional layer coating liquid onto the surface of the catenary part obtained in the step S1, and curing, so as to form a functional layer on the surface of the micro-arc oxidation layer; s2, preparing a hole sealing layer coating solution, and then immersing the catenary part obtained in the S2 into the hole sealing layer coating solution, so that a hole sealing layer is formed on the surface of the functional layer, and finally, a composite anticorrosive coating is formed on the surface of the catenary part. The three anti-corrosion coatings are designed, so that the composite coating is obviously superior to a traditional coating in salt mist resistance, wear resistance, self-repairing performance and the like.

Description

Technical Field

[0001] This invention belongs to the field of anti-corrosion coating technology, specifically relating to a composite anti-corrosion coating suitable for contact wire components and its preparation method. Background Technology

[0002] As a critical component of the rail transit power supply system, overhead contact line components are exposed to outdoor environments for extended periods, especially in coastal areas and heavily polluted sections. They are susceptible to corrosion from seawater salinity, industrial pollutants, and other corrosive media, leading to component failure and impacting the safe and stable operation of the power supply system. Currently, common anti-corrosion treatments for overhead contact line components include hot-dip galvanizing, anodizing, micro-arc oxidation, and epoxy coating. However, these traditional anti-corrosion technologies have significant drawbacks: hot-dip galvanizing coatings are prone to zinc layer peeling and have insufficient salt spray resistance; anodized coatings are relatively thin and have poor scratch resistance; micro-arc oxidation coatings contain numerous micropores, easily becoming channels for corrosive media penetration; and the micropores generated during the curing process of epoxy coatings, along with graphene agglomeration and high conductivity accelerating electrochemical corrosion in graphene-modified epoxy coatings, all fail to meet the long-term anti-corrosion requirements of overhead contact line components in harsh environments.

[0003] With the improvement of anti-corrosion technology, there have been attempts to use graphene or fluorinated graphene as a single modified coating. However, a single modified coating is difficult to solve the problems of micropore sealing, agglomeration inhibition and electrochemical corrosion on the coating surface at the same time. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a composite anti-corrosion coating suitable for overhead contact line components and its preparation method. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] A method for preparing a composite anti-corrosion coating suitable for overhead contact line components, comprising:

[0006] S1: Prepare an electrolyte and place the contact wire components in the electrolyte for micro-arc oxidation treatment, thereby forming a micro-arc oxidation layer with a thickness of 10-20 μm on the surface of the contact wire components; the electrolyte is an aqueous solution of 5-10 g / L sodium silicate, 2-5 g / L sodium hydroxide and 1-3 g / L magnesium sulfate.

[0007] S2: Prepare a functional layer coating liquid, then spray the functional layer coating liquid onto the surface of the contact wire component obtained in S1 and cure it, thereby forming a functional layer with a thickness of 20-40 μm on the surface of the micro-arc oxidation layer; the functional layer coating liquid is formulated according to the following mass fractions: 60-80 parts epoxy resin, 2-4 parts graphene, 3-7 parts fluorinated graphene, 1.5-3 parts coupling agent, 20-30 parts curing agent, and 10-20 parts solvent;

[0008] S3: Prepare a sealing layer coating solution, and then immerse the contact network components obtained in S2 in the sealing layer coating solution to form a sealing layer with a thickness of 3-8 μm on the surface of the functional layer, and finally form a composite anti-corrosion coating on the surface of the contact network components; the preparation process of the sealing layer coating solution is as follows: mix silane coupling agent and ethanol at a volume ratio of 1:5-8, adjust its pH to 4-5, hydrolyze for 30-60 min, add 5-10% of corrosion inhibitor microcapsules according to the total mass of the solution and mix evenly to form a sealing layer coating solution.

[0009] Furthermore, the voltage of the micro-arc oxidation treatment in S1 is 300–450V, and the current density is 10–20A / dm². 2 The micro-arc oxidation treatment time is 20-30 min.

[0010] Further, in S2, the coupling agent is γ-aminopropyltriethoxysilane or γ-ethoxypropyltrimethoxysilane; the curing agent is polyamide 650 or polyamide 651; and the solvent is a solution of xylene and n-butanol mixed in a volume ratio of 2 to 3:1.

[0011] Furthermore, in step S2, the preparation process of the functional layer coating liquid is as follows:

[0012] Graphene and fluorinated graphene are added to a solvent and ultrasonically dispersed evenly. Then, a silane coupling agent is added and stirred for 10-15 minutes. Next, epoxy resin is added and stirred at 1000-1500 r / min for 20-30 minutes. Finally, a curing agent is added and stirred for 5-10 minutes to obtain the functional layer coating solution.

[0013] Further, in step S2, the functional layer coating liquid is sprayed onto the surface of the contact network component obtained in step S1 using electrostatic spraying. The spraying pressure is 0.3-0.5 MPa, the spraying distance is 15-25 cm, and after spraying, the contact network component is pre-cured at 60-80°C for 30-45 min, and then fully cured at 100-120°C for 1-2 h to form the functional layer.

[0014] Furthermore, the preparation process of the fluorinated graphene is as follows:

[0015] The graphene powder was placed in a quartz reaction tube and purged with nitrogen gas at a flow rate of 40–50 mL / min for 30–40 min. Then, a fluorinated gas composed of F2 and N2 in a volume ratio of 1:7–9 was introduced at a flow rate of 30–40 mL / min. The temperature was then raised to 200–250 °C and held for 4–5 h. After the graphene powder cooled, nitrogen gas was introduced to remove residual fluorinated gas, and the powder was washed with anhydrous ethanol 3–5 times. After centrifugation at 5000–6000 r / min for 10–15 min, the powder was dried in a vacuum furnace at a temperature of 60–70 °C for 12–13 h to obtain the fluorinated graphene.

[0016] Furthermore, in step S3, the corrosion inhibitor microcapsules use polyurea-formaldehyde as the wall material and benzotriazole as the corrosion inhibitor, with a particle size of 3–5 μm; and the preparation process is as follows:

[0017] First, benzotriazole and ethanol are mixed evenly at a volume ratio of 3-4:2. Then, 5-10% polyurea formaldehyde (by mass of the solution) is added and stirred to form an emulsion. The emulsion is then heated to 50-60°C, and hydrochloric acid is added to adjust the pH to 2-3. The substances in the emulsion are allowed to react for 2-3 hours to form microcapsule particles. The emulsion is then centrifuged, and the separated microcapsule particles are washed and freeze-dried to obtain corrosion inhibitor microcapsules.

[0018] Furthermore, in step S3, when the contact wire components are immersed in the sealing layer coating liquid, the immersion speed is 5-10 mm / s and the dwell time is 10-20 s. After the immersion coating is completed, the contact wire components are dried at 80-90°C for 60-90 min to form the sealing layer.

[0019] Furthermore, the procedure before step 1 includes:

[0020] The surface of the contact wire components is pretreated, and the pretreatment process includes:

[0021] The contact wire components are immersed in a sodium hydroxide solution with a mass fraction of 5-10% and soaked at 50-60°C for 10-15 minutes. They are then washed with water until neutral and dried. Finally, they are sandblasted until the surface roughness of the contact wire components is 2.4-3.2 μm.

[0022] Another embodiment of the present invention provides a composite anti-corrosion coating suitable for contact wire components, which is prepared by any of the above-described methods for preparing composite anti-corrosion coatings suitable for contact wire components.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention designs a three-layer anti-corrosion coating on the surface of contact wire components. The bottom micro-arc oxidation ceramic layer provides a high-adhesion substrate, the functional layer solves the problems of coating barrier and electrochemical corrosion, and the sealing layer realizes micropore sealing and self-repair. This makes the composite coating significantly superior to traditional coatings in terms of salt spray resistance, wear resistance and self-repair performance.

[0025] 2. This coating can withstand harsh environments such as coastal heat and humidity, heavy pollution, and salt spray, significantly extending the service life of contact network components, reducing maintenance costs, and ensuring the safe and stable operation of the rail transit power supply system. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the composite anti-corrosion coating prepared according to the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1-Contact wire components; 2-Micro-arc oxidation layer; 2-Functional layer; 3-Sealing layer. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0030] Example 1

[0031] This invention provides a method for preparing a composite anti-corrosion coating suitable for contact wire components. Specifically, the contact wire component is an aluminum alloy connecting clamp for contact wires.

[0032] Specifically, the preparation method of this composite anti-corrosion coating includes:

[0033] S1: Pre-treat the surface of the connecting clamp. The pre-treatment process includes:

[0034] The connecting clamp was immersed in an 8% sodium hydroxide solution at 60°C for 12 minutes, then rinsed with deionized water until neutral, and dried at 80°C. Then, it was sandblasted with 100-mesh white corundum sand at a pressure of 0.5 MPa for 4 minutes until the surface roughness of the connecting clamp Ra = 2.4 μm.

[0035] The degreasing process removes oil and oxide scale from the surface of the connecting clamp, and the sandblasting process adjusts the surface roughness of the connecting clamp, thereby improving the mechanical bonding force between the subsequent coating and the connecting clamp.

[0036] S2: Prepare an electrolyte and place the connecting clamp in the electrolyte for micro-arc oxidation treatment, thereby forming a micro-arc oxidation layer with a thickness of 10 μm on the surface of the connecting clamp; the electrolyte is an aqueous solution of 8 g / L sodium silicate, 3 g / L sodium hydroxide and 2 g / L magnesium sulfate.

[0037] Specifically, the voltage during the micro-arc oxidation process is 400V, and the current density is 15A / dm². 2 The micro-arc oxidation treatment time is 20 min. After the micro-arc oxidation treatment is completed, the connecting clamp is removed, rinsed with deionized water, and dried at 90℃ for 45 min to form a micro-arc oxidation layer with a thickness of 10 μm. The micro-arc oxidation layer is a micro-arc oxidation ceramic layer, and the main components of the micro-arc oxidation ceramic layer include Al2O3, SiO2 and MgO.

[0038] A ceramic layer is grown in situ on the surface of the connecting clamp using micro-arc oxidation technology. The high hardness and high adhesion of the ceramic layer provide a stable base for subsequent coatings. At the same time, the dense areas in the ceramic layer can initially block corrosive media. By controlling the electrolyte composition, the pore distribution of the ceramic layer is optimized, and large-diameter defects are reduced.

[0039] S3: Prepare a functional layer coating liquid, then spray the functional layer coating liquid onto the surface of the connecting clamp obtained in S2 and cure it, thereby forming a functional layer with a thickness of 30μm on the surface of the micro-arc oxidation layer; the functional layer coating liquid is prepared according to the following mass fractions: 70 parts epoxy resin, 2 parts graphene, 3 parts fluorinated graphene, 1.5 parts coupling agent, 20 parts curing agent, and 15 parts solvent.

[0040] Preferably, the coupling agent is γ-aminopropyltriethoxysilane or γ-ethoxypropyltrimethoxysilane; the curing agent is polyamide 650 or polyamide 651; and the solvent is a solution of xylene and n-butanol mixed in a volume ratio of 2:1.

[0041] Preferably, the graphene is few-layer graphene prepared by the modified Hummers method, with a purity ≥97%, a sheet thickness of 3-5 nm, and ≤5 layers; the fluorinated graphene is fluorinated graphene prepared by a segmented temperature-controlled gas-phase fluorination method, with a fluorination degree of 35-55% and a volume resistivity ≥10. 10 Ω·cm, hydrophobic contact angle ≥110°.

[0042] Furthermore, the preparation process of the graphene is as follows:

[0043] Flake graphite and sodium nitrate were mixed at a mass ratio of 3:2, and concentrated sulfuric acid was added, with a solid-liquid ratio of 1:22-24 g / mL. The solution was then stirred in an ice bath at 0°C for 25-30 min. Potassium permanganate was then slowly added, with a graphite to potassium permanganate mass ratio of 1:2-3. The mixture was stirred at ≤20°C for 2 h. The solution was then transferred to a constant temperature water bath at 35°C and stirred for 30 min. Deionized water was then slowly added, with a deionized water to concentrated sulfuric acid volume ratio of 1-2:1. The solution was then heated to 98°C and held at that temperature for 15 min, and then deionized water was added. The total water volume to concentrated sulfuric acid volume ratio was 5-6:1, and then 30% hydrogen peroxide was added dropwise until the solution turned bright yellow. The solution was then centrifuged at 8000 r / min for 15 min, washed three times with 5% hydrochloric acid, and then washed with deionized water until pH=7 to obtain graphene oxide. The graphene oxide was dispersed in deionized water at a concentration of 0.5 mg / mL, and ultrasonically exfoliated at 300 W for 60 min, followed by centrifugation at 3000 r / min for 10 min to obtain a graphene dispersion. The graphene dispersion was freeze-dried to obtain graphene powder.

[0044] The graphene was prepared using a modified Hummers method. By controlling the ratio of oxidant (concentrated sulfuric acid + potassium permanganate), reaction temperature, and ultrasonic parameters, high-purity, few-layer graphene was obtained, ensuring its uniform dispersion in the epoxy matrix and exerting a physical barrier effect.

[0045] Furthermore, the preparation process of the fluorinated graphene is as follows:

[0046] Graphene powder was placed in a quartz reaction tube and first purged with nitrogen gas at a flow rate of 50 mL / min for 30 min. Then, a fluorinated gas composed of F2 and N2 in a volume ratio of 1:9 was introduced at a flow rate of 30 mL / min. The temperature was then raised to 200 °C and held for 4 h. After the graphene powder cooled, nitrogen gas was introduced to remove residual fluorinated gas, and the powder was washed three times with anhydrous ethanol. After centrifugation at 6000 r / min for 10 min, the powder was dried in a vacuum furnace at 60 °C for 12 h to obtain fluorinated graphene.

[0047] The fluorinated graphene was prepared by a segmented temperature-controlled gas-phase fluorination method, with the degree of fluorination controlled between 35% and 55%. This balanced hydrophobicity and interfacial compatibility, ensuring low conductivity to suppress galvanic corrosion while avoiding a decrease in bonding strength with epoxy resin due to excessive fluorination.

[0048] Specifically, the preparation process of the functional layer coating liquid is as follows:

[0049] According to the above-mentioned proportions, graphene and fluorinated graphene are added to the solvent and dispersed in an ultrasonic bath at 250W power for 35 minutes until they are uniformly dispersed. Then, coupling agent is added and stirred for 12 minutes. Epoxy resin is then added and stirred at a high speed of 1200r / min for 25 minutes. Finally, polyamide 650 is added and stirred for 8 minutes to obtain the functional layer coating solution.

[0050] Specifically, during the spraying process, the functional layer coating liquid is sprayed onto the surface of the connecting clamp obtained in S2 using electrostatic spraying. The spraying pressure is 0.4 MPa, the spraying distance is 20 cm, and the coating thickness is 30 μm. After spraying, the connecting clamp is pre-cured at 60°C for 40 min and then fully cured at 110°C for 1.5 h to form the functional layer. Staged curing can reduce the micropores caused by the curing shrinkage of epoxy resin.

[0051] The functional layer is a fluorinated epoxy composite layer, with epoxy resin as the matrix and graphene and fluorinated graphene compounded together. The high barrier properties of graphene reduce micropores in the coating, while the low conductivity of fluorinated graphene inhibits electrochemical corrosion. Together, they solve the defects of traditional graphene-modified coatings. In addition, the addition of a coupling agent can improve the interfacial bonding between fluorinated graphene and epoxy resin and inhibit agglomeration.

[0052] S4: Prepare a sealing layer coating solution, and then immerse the connecting clamp obtained in S3 in the sealing layer coating solution to form a sealing layer with a thickness of 5μm on the surface of the functional layer, and finally form a composite anti-corrosion coating on the surface of the connecting clamp; the preparation process of the sealing layer coating solution is as follows: mix silane coupling agent and ethanol at a volume ratio of 1:6, add deionized water to adjust its pH to 4.5, and after hydrolysis for 45min (using the added deionized water to react with other substances), add corrosion inhibitor microcapsules accounting for 5% of the total mass of the solution, and then ultrasonically disperse at 200W for 18min to make it uniformly mixed to form a sealing layer coating solution.

[0053] Specifically, in this embodiment of the invention, the corrosion inhibitor microcapsules use polyurea-formaldehyde as the wall material and benzotriazole as the corrosion inhibitor (i.e., the core material), with a particle size of 3 μm. The particle size of the corrosion inhibitor microcapsules is controlled to match the thickness of the sealing layer, ensuring that the corrosion inhibitor microcapsules are uniformly distributed and do not affect the density of the coating.

[0054] Furthermore, the preparation process of this corrosion inhibitor microcapsule is as follows:

[0055] First, benzotriazole and ethanol were mixed at a volume ratio of 3:2 to dissolve the benzotriazole in the ethanol. Then, 8% of the total mass of the solution of prepolymer polyurea formaldehyde was added and stirred to form an emulsion. The emulsion was then heated to 55°C and hydrochloric acid was added to adjust the pH to 2.5. The substances in the emulsion were allowed to react for 2.5 hours to form microcapsule particles. The emulsion was then centrifuged, and the separated microcapsule particles were washed with deionized water until neutral. After freeze-drying, corrosion inhibitor microcapsules were obtained.

[0056] Furthermore, when the connecting clamp is immersed in the sealing layer coating liquid, the immersion speed is 8 mm / s and the residence time is 15s. After the immersion coating is completed, the contact wire components are dried at 85°C for 75 minutes to form the sealing layer.

[0057] The sealing layer is a silane layer containing corrosion inhibitor microcapsules. Silane material is used to seal the residual micropores on the surface of the functional layer and the micro-arc oxidation bottom layer. At the same time, corrosion inhibitor microcapsules are introduced. When the coating is slightly scratched, the microcapsules rupture and release the corrosion inhibitor, achieving self-repair and corrosion protection, and further extending the service life of the coating.

[0058] S5: Finally, inspect the appearance of the connecting clamp, remove surface impurities, and make local repairs if necessary to obtain the finished connecting clamp with a composite anti-corrosion coating on the surface.

[0059] Example 2

[0060] This invention provides a method for preparing a composite anti-corrosion coating suitable for contact wire components. Specifically, the contact wire component is an aluminum alloy base for contact wires.

[0061] Specifically, the preparation method of this composite anti-corrosion coating includes:

[0062] S1: Pre-treat the surface of the base. The pre-treatment process includes:

[0063] The base was immersed in a 10% sodium hydroxide solution at 55°C for 15 minutes to degrease it. Then it was rinsed with deionized water until neutral and dried at 80°C. Next, it was sandblasted with 80-mesh white corundum sand at a pressure of 0.6 MPa for 5 minutes until the surface roughness Ra of the base was 3.2 μm.

[0064] The degreasing process removes oil and oxide scale from the base surface, and the sandblasting process adjusts the surface roughness of the base, thereby improving the mechanical adhesion between the subsequent coating and the base.

[0065] S2: Prepare an electrolyte and place the base in the electrolyte for micro-arc oxidation treatment, thereby forming a micro-arc oxidation layer with a thickness of 15μm on the surface of the base; the electrolyte is an aqueous solution of 10g / L sodium silicate, 5g / L sodium hydroxide and 3g / L magnesium sulfate.

[0066] Specifically, the voltage during the micro-arc oxidation process is 450V, and the current density is 20A / dm². 2 The micro-arc oxidation treatment time is 25 min. After the micro-arc oxidation treatment is completed, the base is taken out and rinsed with deionized water, and then dried at 95℃ for 60 min to form a micro-arc oxidation layer with a thickness of 15 μm. The micro-arc oxidation layer is a micro-arc oxidation ceramic layer, and the main components of the micro-arc oxidation ceramic layer include Al2O3, SiO2 and MgO.

[0067] A ceramic layer is grown in situ on the base surface using micro-arc oxidation technology. The high hardness and high adhesion of the ceramic layer provide a stable base for subsequent coatings. At the same time, the dense areas in the ceramic layer can initially block corrosive media. By controlling the composition of the electrolyte, the pore distribution of the ceramic layer is optimized, and large-diameter defects are reduced.

[0068] S3: Prepare a functional layer coating liquid, then spray the functional layer coating liquid onto the surface of the base obtained in S2 and cure it, thereby forming a functional layer with a thickness of 40μm on the surface of the micro-arc oxidation layer; the functional layer coating liquid is prepared according to the following mass fractions: 80 parts epoxy resin, 3 parts graphene, 5 parts fluorinated graphene, 2 parts coupling agent, 25 parts curing agent, and 20 parts solvent.

[0069] Preferably, the coupling agent is γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane; the curing agent is polyamide 650 or polyamide 651; and the solvent is a solution of xylene and n-butanol mixed in a volume ratio of 3:1.

[0070] Preferably, the graphene is few-layer graphene prepared by a modified Hummers method, with a purity ≥97%, a sheet thickness of 3-5 nm, and ≤5 layers; the fluorinated graphene is fluorinated graphene prepared by a segmented temperature-controlled gas-phase fluorination method, with a fluorination degree of 35-55% and a volume resistivity ≥10¹⁸. 0 Ω·cm, hydrophobic contact angle ≥110°.

[0071] Furthermore, the preparation process of the graphene is as follows:

[0072] Flake graphite and sodium nitrate were mixed at a mass ratio of 3–5:2, and concentrated sulfuric acid was added, with a solid-liquid ratio of 1:22–24 g / mL. The solution was then stirred in an ice bath at 0°C for 25–30 min. Potassium permanganate was then slowly added, with a graphite to potassium permanganate mass ratio of 1:2–3. The mixture was stirred at ≤20°C for 2 h. The solution was then transferred to a constant temperature water bath at 35°C and stirred for 30 min. Deionized water was then slowly added, with a deionized water to concentrated sulfuric acid volume ratio of 1–2:1. The solution was then heated to 98°C and held at that temperature for 15 min, and then deionized water was added. The total water volume to concentrated sulfuric acid volume ratio was 5-6:1, and then 30% hydrogen peroxide was added dropwise until the solution turned bright yellow. The solution was then centrifuged at 8000 r / min for 15 min, washed three times with 5% hydrochloric acid, and then washed with deionized water until pH=7 to obtain graphene oxide. The graphene oxide was dispersed in deionized water at a concentration of 0.5 mg / mL, and ultrasonically exfoliated at 300 W for 60 min, followed by centrifugation at 3000 r / min for 10 min to obtain a graphene dispersion. The graphene dispersion was freeze-dried to obtain graphene powder.

[0073] The graphene was prepared using a modified Hummers method. By controlling the ratio of oxidant (concentrated sulfuric acid + potassium permanganate), reaction temperature, and ultrasonic parameters, high-purity, few-layer graphene was obtained, ensuring its uniform dispersion in the epoxy matrix and exerting a physical barrier effect.

[0074] Furthermore, the preparation process of the fluorinated graphene is as follows:

[0075] Graphene powder was placed in a quartz reaction tube and first purged with nitrogen gas at a flow rate of 45 mL / min for 35 min. Then, a fluorinated gas composed of F2 and N2 in a volume ratio of 1:8 was introduced at a flow rate of 35 mL / min. The temperature was then raised to 250 °C and held for 5 h. After the graphene powder cooled, nitrogen gas was introduced to remove residual fluorinated gas, and the powder was washed five times with anhydrous ethanol. After centrifugation at 5500 r / min for 15 min, the powder was dried in a vacuum furnace at 70 °C for 13 h to obtain fluorinated graphene.

[0076] The fluorinated graphene was prepared by a segmented temperature-controlled gas-phase fluorination method, with the degree of fluorination controlled between 35% and 55%. This balanced hydrophobicity and interfacial compatibility, ensuring low conductivity to suppress galvanic corrosion while avoiding a decrease in bonding strength with epoxy resin due to excessive fluorination.

[0077] Specifically, the preparation process of the functional layer coating liquid is as follows:

[0078] According to the above-mentioned proportions, graphene and fluorinated graphene are added to the solvent and dispersed in an ultrasonic bath at 200W power for 40 minutes until they are uniformly dispersed. Then, coupling agent is added and stirred for 15 minutes. Epoxy resin is then added and stirred at 1500r / min for 30 minutes. Finally, polyamide 650 is added and stirred for 10 minutes to obtain the functional layer coating solution.

[0079] Specifically, during the spraying process, the functional layer coating liquid is sprayed onto the surface of the base obtained in S2 using electrostatic spraying. The spraying pressure is 0.5 MPa, the spraying distance is 25 cm, and the coating thickness is 40 μm. After spraying, the base is pre-cured at 70°C for 30 min and then fully cured at 120°C for 2 h to form the functional layer. Staged curing can reduce the micropores caused by the curing shrinkage of epoxy resin.

[0080] The functional layer is a fluorinated epoxy composite layer, with epoxy resin as the matrix and graphene and fluorinated graphene compounded together. The high barrier properties of graphene reduce micropores in the coating, while the low conductivity of fluorinated graphene inhibits electrochemical corrosion. Together, they solve the defects of traditional graphene-modified coatings. In addition, the addition of a coupling agent can improve the interfacial bonding between fluorinated graphene and epoxy resin and inhibit agglomeration.

[0081] S4: Prepare a sealing layer coating solution, and then immerse the base obtained in S3 in the sealing layer coating solution to form a sealing layer with a thickness of 8μm on the surface of the functional layer, and finally form a composite anti-corrosion coating on the surface of the base; The preparation process of the sealing layer coating solution is as follows: mix silane coupling agent and ethanol at a volume ratio of 1:8, add deionized water to adjust its pH to 5, and after hydrolysis for 60min (using the added deionized water to react with other substances), add corrosion inhibitor microcapsules accounting for 10% of the total mass of the solution, and then ultrasonically disperse at 200W for 20min to make it evenly mixed to form a sealing layer coating solution.

[0082] Specifically, in this embodiment of the invention, the corrosion inhibitor microcapsules use polyurea-formaldehyde as the wall material and benzotriazole as the corrosion inhibitor (i.e., the core material), with a particle size of 5 μm. The particle size of the corrosion inhibitor microcapsules is controlled to match the thickness of the sealing layer, ensuring that the corrosion inhibitor microcapsules are uniformly distributed and do not affect the density of the coating.

[0083] Furthermore, the preparation process of this corrosion inhibitor microcapsule is as follows:

[0084] First, benzotriazole and ethanol were mixed at a volume ratio of 4:2 to dissolve the benzotriazole in the ethanol. Then, 10% of the total mass of the solution of prepolymer polyurea formaldehyde was added and stirred to form an emulsion. The emulsion was then heated to 60°C and hydrochloric acid was added to adjust the pH to 3. The substances in the emulsion were allowed to react for 3 hours to form microcapsule particles. The emulsion was then centrifuged, and the separated microcapsule particles were washed with deionized water until neutral. After freeze-drying, corrosion inhibitor microcapsules were obtained.

[0085] Furthermore, when the base is immersed in the sealing layer coating liquid, the immersion speed is 5 mm / s and the dwell time is 20 s. After the immersion coating is completed, the contact wire components are dried at 90°C for 90 min to form the sealing layer.

[0086] The sealing layer is a silane layer containing corrosion inhibitor microcapsules. Silane material is used to seal the residual micropores on the surface of the functional layer and the micro-arc oxidation bottom layer. At the same time, corrosion inhibitor microcapsules are introduced. When the coating is slightly scratched, the microcapsules rupture and release the corrosion inhibitor, achieving self-repair and corrosion protection, and further extending the service life of the coating.

[0087] S5: Finally, inspect the appearance of the base, remove surface impurities, and make local repairs if necessary to obtain the finished base with a composite anti-corrosion coating on the surface.

[0088] Example 3

[0089] This invention provides a method for preparing a composite anti-corrosion coating suitable for contact wire components. Specifically, the contact wire component is an aluminum alloy connecting lug for the contact wire.

[0090] Specifically, the preparation method of this composite anti-corrosion coating includes:

[0091] S1: Pre-treat the surface of the connecting ears, the pre-treatment process including:

[0092] The connecting lugs were immersed in a 5% sodium hydroxide solution at 50°C for 10 minutes, then rinsed with deionized water until neutral, and dried at 80°C. Then, they were sandblasted with 90-mesh white corundum sand at a pressure of 0.4 MPa for 6 minutes until the surface roughness of the connecting lugs Ra = 2.8 μm.

[0093] The degreasing process removes oil and oxide scale from the surface of the connecting ears, and the sandblasting process adjusts the surface roughness of the connecting ears, thereby improving the mechanical bonding force between the subsequent coating and the connecting ears.

[0094] S2: Prepare an electrolyte and place the connecting ears in the electrolyte for micro-arc oxidation treatment, thereby forming a micro-arc oxidation layer with a thickness of 20 μm on the surface of the connecting ears; the electrolyte is an aqueous solution of 5 g / L sodium silicate, 2 g / L sodium hydroxide and 1 g / L magnesium sulfate.

[0095] Specifically, the voltage during the micro-arc oxidation process is 300V, and the current density is 10A / dm³. 2 The micro-arc oxidation treatment time is 30 min. After the micro-arc oxidation treatment is completed, the connecting ears are removed, rinsed with deionized water, and dried at 80℃ for 30 min to form a micro-arc oxidation layer with a thickness of 20 μm. The micro-arc oxidation layer is a micro-arc oxidation ceramic layer, and the main components of the micro-arc oxidation ceramic layer include Al2O3, SiO2 and MgO.

[0096] A ceramic layer is grown in situ on the surface of the connecting ears using micro-arc oxidation technology. The high hardness and high adhesion of the ceramic layer provide a stable base for subsequent coatings. At the same time, the dense areas in the ceramic layer can initially block corrosive media. By controlling the composition of the electrolyte, the pore distribution of the ceramic layer is optimized, and large-diameter defects are reduced.

[0097] S3: Prepare a functional layer coating liquid, then spray the functional layer coating liquid onto the surface of the connecting double ear obtained in S2 and cure it, thereby forming a functional layer with a thickness of 20μm on the surface of the micro-arc oxidation layer; the functional layer coating liquid is prepared according to the following mass fractions: 60 parts epoxy resin, 4 parts graphene, 7 parts fluorinated graphene, 3 parts coupling agent, 30 parts curing agent, and 10 parts solvent.

[0098] Preferably, the coupling agent is γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane; the curing agent is polyamide 650 or polyamide 651; and the solvent is a solution of xylene and n-butanol mixed in a volume ratio of 2.5:1.

[0099] Preferably, the graphene is few-layer graphene prepared by the modified Hummers method, with a purity ≥97%, a sheet thickness of 3-5 nm, and a number of layers ≤5; the fluorinated graphene is fluorinated graphene prepared by the segmented temperature-controlled gas-phase fluorination method, with a fluorination degree of 35-55%, a volume resistivity ≥10¹⁰ Ω·cm, and a hydrophobic contact angle ≥110°.

[0100] Furthermore, the preparation process of the graphene is as follows:

[0101] Flake graphite and sodium nitrate were mixed at a mass ratio of 3–5:2, and concentrated sulfuric acid was added, with a solid-liquid ratio of 1:22–24 g / mL. The solution was then stirred in an ice bath at 0°C for 25–30 min. Potassium permanganate was then slowly added, with a graphite to potassium permanganate mass ratio of 1:2–3. The mixture was stirred at ≤20°C for 2 h. The solution was then transferred to a constant temperature water bath at 35°C and stirred for 30 min. Deionized water was then slowly added, with a deionized water to concentrated sulfuric acid volume ratio of 1–2:1. The solution was then heated to 98°C and held at that temperature for 15 min, and then deionized water was added. The total water volume to concentrated sulfuric acid volume ratio was 5-6:1, and then 30% hydrogen peroxide was added dropwise until the solution turned bright yellow. The solution was then centrifuged at 8000 r / min for 15 min, washed three times with 5% hydrochloric acid, and then washed with deionized water until pH=7 to obtain graphene oxide. The graphene oxide was dispersed in deionized water at a concentration of 0.5 mg / mL, and ultrasonically exfoliated at 300 W for 60 min, followed by centrifugation at 3000 r / min for 10 min to obtain a graphene dispersion. The graphene dispersion was freeze-dried to obtain graphene powder.

[0102] The graphene was prepared using a modified Hummers method. By controlling the ratio of oxidant (concentrated sulfuric acid + potassium permanganate), reaction temperature, and ultrasonic parameters, high-purity, few-layer graphene was obtained, ensuring its uniform dispersion in the epoxy matrix and exerting a physical barrier effect.

[0103] Furthermore, the preparation process of the fluorinated graphene is as follows:

[0104] Graphene powder was placed in a quartz reaction tube and first purged with nitrogen gas at a flow rate of 40 mL / min for 40 min. Then, a fluorinated gas composed of F2 and N2 in a volume ratio of 1:7 was introduced at a flow rate of 40 mL / min. The temperature was then raised to 230 °C and held for 4.5 h. After the graphene powder cooled, nitrogen gas was introduced to remove residual fluorinated gas, and the powder was washed four times with anhydrous ethanol. After centrifugation at 5000 r / min for 13 min, the powder was dried in a vacuum furnace at 65 °C for 12.5 h to obtain fluorinated graphene.

[0105] The fluorinated graphene was prepared by a segmented temperature-controlled gas-phase fluorination method, with the degree of fluorination controlled between 35% and 55%. This balanced hydrophobicity and interfacial compatibility, ensuring low conductivity to suppress galvanic corrosion while avoiding a decrease in bonding strength with epoxy resin due to excessive fluorination.

[0106] Specifically, the preparation process of the functional layer coating liquid is as follows:

[0107] According to the above-mentioned proportions, graphene and fluorinated graphene are added to the solvent and dispersed in an ultrasonic bath at 230W power for 45 minutes until they are uniformly dispersed. Then, coupling agent is added and stirred for 10 minutes. Epoxy resin is then added and stirred at 1000 r / min for 20 minutes. Finally, polyamide 650 is added and stirred for 5 minutes to obtain the functional layer coating solution.

[0108] Specifically, during the spraying process, the functional layer coating liquid is sprayed onto the surface of the connecting ears obtained in S2 using electrostatic spraying. The spraying pressure is 0.3 MPa, the spraying distance is 15 cm, and the coating thickness is 20 μm. After spraying, the connecting ears are pre-cured at 80°C for 45 min, and then fully cured at 100°C for 1 h to form the functional layer. Staged curing can reduce the micropores caused by the curing shrinkage of epoxy resin.

[0109] The functional layer is a fluorinated epoxy composite layer, with epoxy resin as the matrix and graphene and fluorinated graphene compounded together. The high barrier properties of graphene reduce micropores in the coating, while the low conductivity of fluorinated graphene inhibits electrochemical corrosion. Together, they solve the defects of traditional graphene-modified coatings. In addition, the addition of a coupling agent can improve the interfacial bonding between fluorinated graphene and epoxy resin and inhibit agglomeration.

[0110] S4: Prepare a sealing layer coating solution, and then immerse the connecting ears obtained in S3 in the sealing layer coating solution to form a sealing layer with a thickness of 3μm on the surface of the functional layer, and finally form a composite anti-corrosion coating on the surface of the connecting ears; The preparation process of the sealing layer coating solution is as follows: mix silane coupling agent and ethanol at a volume ratio of 1:5, add deionized water to adjust its pH to 4, and after hydrolysis for 30 minutes (using the added deionized water to react with other substances), add corrosion inhibitor microcapsules accounting for 8% of the total mass of the solution, and then ultrasonically disperse at 200W for 19 minutes to make it evenly mixed to form a sealing layer coating solution.

[0111] Specifically, in this embodiment of the invention, the corrosion inhibitor microcapsules use polyurea-formaldehyde as the wall material and benzotriazole as the corrosion inhibitor (i.e., the core material), with a particle size of 4 μm. The particle size of the corrosion inhibitor microcapsules is controlled to match the thickness of the sealing layer, ensuring that the corrosion inhibitor microcapsules are uniformly distributed and do not affect the density of the coating.

[0112] Furthermore, the preparation process of this corrosion inhibitor microcapsule is as follows:

[0113] First, benzotriazole and ethanol were mixed at a volume ratio of 3.5:2 to dissolve the benzotriazole in the ethanol. Then, 5% of the total mass of the solution of prepolymer polyurea formaldehyde was added and stirred to form an emulsion. The emulsion was then heated to 50°C and hydrochloric acid was added to adjust the pH to 2. The substances in the emulsion were allowed to react for 2 hours to form microcapsule particles. The emulsion was then centrifuged, and the separated microcapsule particles were washed with deionized water until neutral. After freeze-drying, corrosion inhibitor microcapsules were obtained.

[0114] Furthermore, when immersing the connecting ears in the sealing layer coating liquid, the immersion speed is 10 mm / s and the residence time is 10 s. After the immersion coating is completed, the contact wire components are dried at 80°C for 60 min to form the sealing layer.

[0115] The sealing layer is a silane layer containing corrosion inhibitor microcapsules. Silane material is used to seal the residual micropores on the surface of the functional layer and the micro-arc oxidation bottom layer. At the same time, corrosion inhibitor microcapsules are introduced. When the coating is slightly scratched, the microcapsules rupture and release the corrosion inhibitor, achieving self-repair and corrosion protection, and further extending the service life of the coating.

[0116] S5: Finally, inspect the appearance of the connecting ears, remove surface impurities, and make local repairs if necessary to obtain the finished connecting ears with a composite anti-corrosion coating on the surface.

[0117] The performance of the composite anti-corrosion coatings prepared in Examples 1 to 3 was tested, and the results are as follows:

[0118] (1) Adhesion test: According to GB / T9286-1998, the cross-cut test is performed. The adhesion level is 0, that is, the cut edge is smooth and no grid is peeled off.

[0119] (2) Neutral salt spray test: According to GB / T10125-2021, 35℃±2℃, 5% NaCl solution, salt spray deposition rate 1.0-2.0mL / (h·80cm) 2 After 1000 hours of testing, the corrosion area of ​​the coating was ≤1%, and the substrate showed no corrosion.

[0120] (3) Alternating damp heat test: According to GB / T2423.4-2008, after 6 cycles, the coating did not blister or peel off, and there was no obvious change in appearance.

[0121] (4) Wear resistance test: reciprocating friction test (load 5N, 1000 cycles), wear volume ≤0.03mm 3 Superior to traditional epoxy coatings (0.08mm) 3 ).

[0122] (5) Self-healing performance test: The coating surface was scratched with a scratcher (depth 50μm). After 200h of salt spray test, there was no obvious corrosion expansion at the scratch, and the corrosion inhibitor microcapsules played a self-healing role.

[0123] Example 4

[0124] This invention discloses a composite anti-corrosion coating suitable for overhead contact line components, such as... Figure 1 As shown, it is prepared by the method for preparing a composite anti-corrosion coating suitable for contact wire components according to Examples 1 to 3. The composite anti-corrosion coating includes, from the substrate surface of the contact wire component 1 outwards, a micro-arc oxidation layer 2, a functional layer 3, and a sealing layer 4.

[0125] The micro-arc oxidation layer 2 is a micro-arc oxidation ceramic layer with a thickness of 10-20 μm; the functional layer 3 is a fluorinated epoxy composite layer with a thickness of 20-40 μm; and the sealing layer 4 is a silane layer containing corrosion inhibitor microcapsules with a thickness of 3-8 μm.

[0126] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite anti-corrosion coating suitable for overhead contact line components, characterized in that, include: S1: Prepare an electrolyte and place the contact wire components in the electrolyte for micro-arc oxidation treatment, thereby forming a micro-arc oxidation layer with a thickness of 10-20 μm on the surface of the contact wire components; the electrolyte is an aqueous solution of 5-10 g / L sodium silicate, 2-5 g / L sodium hydroxide and 1-3 g / L magnesium sulfate. S2: Prepare a functional layer coating liquid, then spray the functional layer coating liquid onto the surface of the contact wire component obtained in S1 and cure it, thereby forming a functional layer with a thickness of 20-40 μm on the surface of the micro-arc oxidation layer; the functional layer coating liquid is formulated according to the following mass fractions: 60-80 parts epoxy resin, 2-4 parts graphene, 3-7 parts fluorinated graphene, 1.5-3 parts coupling agent, 20-30 parts curing agent, and 10-20 parts solvent; S3: Prepare a sealing layer coating solution, and then immerse the contact network components obtained in S2 in the sealing layer coating solution to form a sealing layer with a thickness of 3-8 μm on the surface of the functional layer, and finally form a composite anti-corrosion coating on the surface of the contact network components; the preparation process of the sealing layer coating solution is as follows: mix silane coupling agent and ethanol at a volume ratio of 1:5-8, adjust its pH to 4-5, hydrolyze for 30-60 min, add 5-10% of corrosion inhibitor microcapsules according to the total mass of the solution and mix evenly to form a sealing layer coating solution.

2. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 1, characterized in that, The voltage of the micro-arc oxidation treatment in S1 is 300-450V, the current density is 10-20A / dm2, and the micro-arc oxidation treatment time is 20-30min.

3. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 1, characterized in that, In step S2, the coupling agent is γ-aminopropyltriethoxysilane or γ-ethoxypropyltrimethoxysilane; the curing agent is polyamide 650 or polyamide 651; and the solvent is a solution of xylene and n-butanol mixed in a volume ratio of 2 to 3:

1.

4. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 3, characterized in that, In step S2, the preparation process of the functional layer coating liquid is as follows: Graphene and fluorinated graphene are added to a solvent and ultrasonically dispersed evenly. Then, a silane coupling agent is added and stirred for 10-15 minutes. Next, epoxy resin is added and stirred at 1000-1500 r / min for 20-30 minutes. Finally, a curing agent is added and stirred for 5-10 minutes to obtain the functional layer coating solution.

5. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 4, characterized in that, In step S2, the functional layer coating liquid is sprayed onto the surface of the contact wire component obtained in step S1 using electrostatic spraying. The spraying pressure is 0.3-0.5 MPa and the spraying distance is 15-25 cm. After spraying, the contact wire component is pre-cured at 60-80°C for 30-45 min and then fully cured at 100-120°C for 1-2 h to form the functional layer.

6. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 1, characterized in that, The preparation process of the fluorinated graphene is as follows: The graphene powder was placed in a quartz reaction tube and purged with nitrogen gas at a flow rate of 40–50 mL / min for 30–40 min. Then, a fluorinated gas composed of F2 and N2 in a volume ratio of 1:7–9 was introduced at a flow rate of 30–40 mL / min. The temperature was then raised to 200–250 °C and held for 4–5 h. After the graphene powder cooled, nitrogen gas was introduced to remove residual fluorinated gas, and the powder was washed with anhydrous ethanol 3–5 times. After centrifugation at 5000–6000 r / min for 10–15 min, the powder was dried in a vacuum furnace at a temperature of 60–70 °C for 12–13 h to obtain the fluorinated graphene.

7. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 1, characterized in that, In step S3, the corrosion inhibitor microcapsules use polyurea-formaldehyde as the wall material and benzotriazole as the corrosion inhibitor, with a particle size of 3–5 μm; and the preparation process is as follows: First, benzotriazole and ethanol are mixed evenly at a volume ratio of 3-4:

2. Then, 5-10% polyurea formaldehyde (by mass of the solution) is added and stirred to form an emulsion. The emulsion is then heated to 50-60°C, and hydrochloric acid is added to adjust the pH to 2-3. The substances in the emulsion are allowed to react for 2-3 hours to form microcapsule particles. The emulsion is then centrifuged, and the separated microcapsule particles are washed and freeze-dried to obtain corrosion inhibitor microcapsules.

8. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 6, characterized in that, In step S3, when the contact wire components are immersed in the sealing layer coating liquid, the immersion speed is 5-10 mm / s and the dwell time is 10-20 s. After the immersion coating is completed, the contact wire components are dried at 80-90°C for 60-90 min to form the sealing layer.

9. The method for preparing a composite anti-corrosion coating suitable for contact wire components according to claim 1, characterized in that, Before step 1, the following also applies: The surface of the contact wire components is pretreated, and the pretreatment process includes: The contact wire components are immersed in a sodium hydroxide solution with a mass fraction of 5-10% and soaked at 50-60°C for 10-15 minutes. They are then washed with water until neutral and dried. Finally, they are sandblasted until the surface roughness of the contact wire components is 2.4-3.2 μm.

10. A composite anti-corrosion coating suitable for overhead contact line components, characterized in that, It is prepared by the method for preparing composite anti-corrosion coatings applicable to contact wire components as described in any one of claims 1 to 9.

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