Conductive anti-corrosion coating material with self-repairing function and preparation method thereof

Abstract

The invention relates to the technical field of anti-corrosion coating materials, in particular to a conductive anti-corrosion coating material with a self-repairing function and a preparation method of the conductive anti-corrosion coating material. The preparation method comprises the following steps: loading a corrosion inhibitor 1, 10-phenanthroline by taking ZIF-8 / GO as a carrier to prepare a ZIF-8 / GO / Phen material; a ZIF-8 / GO / Phen material and a carbon tube dispersion liquid are used as fillers and are mixed with epoxy acrylic resin to prepare a conductive anticorrosive coating; the conductive anti-corrosion coating is coated on the surface of a metal base material to form an anti-corrosion coating, and finally, a layer of conductive polymer is deposited on the outer layer by adopting an electrochemical method to obtain the conductive anti-corrosion coating material. The conductive anti-corrosion coating material prepared by the invention has a self-repairing function in an acidic working environment, can realize long-acting corrosion resistance, and can be applied to the field of fuel cells as a metal bipolar plate protection material.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating materials technology, specifically to a conductive anti-corrosion coating material with self-healing function and its preparation method. Background Technology

[0002] With social progress and technological development, fuel cells have experienced rapid growth due to their advantages such as high efficiency, low pollution and noise, strong adaptability, short construction period, and simple maintenance. Currently, proton exchange membrane fuel cells (PEMFCs) are keeping pace with the times, demonstrating advantages such as high efficiency, green and environmentally friendly characteristics, sustainable development, and high reliability in energy conversion and environmentally friendly storage. PEMFCs can efficiently convert the chemical energy of hydrogen and oxygen into electrical energy, exhibiting excellent performance.

[0003] Metal bipolar plates are a key component of fuel cells, possessing excellent electrical and thermal conductivity and superior machinability. However, the generation of stagnant water and the degradation of the proton exchange membrane during fuel cell operation make metal bipolar plates susceptible to corrosion during long-term service. Furthermore, the weakly acidic water generated during operation may cause the oxide film on the bipolar plate side to thicken, reducing the bipolar plate's conductivity and thus degrading battery performance. Therefore, establishing an anti-corrosion coating on the surface of the metal bipolar plate is a primary method to improve its performance.

[0004] Chinese patent CN202211645162.1 discloses an impregnation resin composed of several acrylates modified with different functional groups. This resin is applied to bipolar plates to improve corrosion resistance. However, the organic coating fails rapidly in acidic environments, resulting in poor corrosion protection. Chinese patent CN202310630129.X reports a corrosion protection method for metal bipolar plates. An anti-corrosion liquid is prepared using hydroxyacrylic acid, isocyanate, dispersant, solvent, aluminum silver paste, graphite, and titanium carbide as raw materials and coated onto the surface of the metal bipolar plate. Conductive nanofillers such as aluminum silver paste and graphite extend the diffusion path of the corrosive medium. However, this method is difficult to achieve long-term corrosion protection. Existing technologies still have unresolved core issues such as controlled release of corrosion inhibitors, synergistic protection through multiple mechanisms, and long-term stability of the coating. There is an urgent need to develop a novel composite coating material. Summary of the Invention

[0005] The purpose of this invention is to provide a conductive anti-corrosion coating material with self-healing function and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a conductive anti-corrosion coating material with self-healing function, comprising the following steps: Step 1: After mixing zinc acetate dihydrate / methanol solution and graphene oxide dispersion, dimethylimidazole / methanol solution was added, and the mixture was stirred in a water bath at 25~30℃ for 24h to obtain a reaction solution. The reaction solution was centrifuged until the supernatant was colorless and transparent, and the solid precipitate was collected after solid-liquid separation. After washing with methanol, vacuum drying, and grinding, gray-black ZIF-8 / GO nanoparticles were obtained. Step 2: Add 1,10-phenanthroline and ZIF-8 / GO nanoparticles sequentially to methanol and stir to obtain a dispersion solution; let the dispersion solution stand at 25~30℃ under vacuum for 6~8h, centrifuge until the supernatant is colorless and transparent, separate the solid and liquid and collect the solid precipitate, wash the solid precipitate with methanol, wrap it in tin foil and dry it at 50~60℃ to obtain ZIF-8 / GO / Phen material; Step 3: Mix the carbon nanotube dispersion with epoxy acrylic resin, stir for 3-5 minutes, then add carbon nanotubes and ZIF-8 / GO / Phen material, and continue stirring for 24 hours to obtain a conductive anti-corrosion coating. Step 4: Select a metal substrate for surface pretreatment, apply conductive anti-corrosion coating to the surface of the metal substrate using roller coating method, and heat cure to form an anti-corrosion coating; use constant current deposition method to deposit conductive polymer on the surface of the anti-corrosion coating, rinse the surface with deionized water after deposition is completed, and dry to obtain conductive anti-corrosion coating material.

[0007] Further, in step 1, the zinc acetate dihydrate / methanol solution, the graphene oxide dispersion, and the dimethylimidazole / methanol solution are mixed at a volume ratio of 2:1:3; wherein the concentration of the zinc acetate dihydrate / methanol solution is 0.05~0.1g / mL, the concentration of the graphene oxide dispersion is 3~5mg / mL, and the concentration of the dimethylimidazole / methanol solution is 0.1~0.25g / mL.

[0008] Furthermore, in step 2, the dispersion contains 30-60 mg / mL of 1,10-phenanthroline and 5-20 mg / mL of ZIF-8 / GO.

[0009] Further, in step 3, the concentration of the carbon nanotube dispersion is 0.3~0.5 wt.%; in the conductive anti-corrosion coating, the weight ratio of carbon nanotube dispersion, epoxy acrylate resin, and carbon nanotubes is (13~16):(4.5~6):(0.28~0.32), and the content of ZIF-8 / GO / Phen material is 0.5~2.0 wt.%.

[0010] Furthermore, in step 4, the surface pretreatment process of the metal substrate is as follows: first, use sandpaper to grind in one direction to remove the oxide layer on the surface, then perform polishing treatment, and finally rinse and dry with deionized water and anhydrous ethanol.

[0011] Furthermore, in step 4, the thermosetting conditions are: drying and curing at 55~65℃ for 24 hours.

[0012] Furthermore, in step 4, the constant current deposition method uses a mixed solution of conductive polymer monomer and protic acid as the electrolyte, a metal substrate coated with an anti-corrosion coating as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode, with a deposition current density of 1~2 mA / cm². 2 .

[0013] Furthermore, the conductive polymer monomer is any one of pyrrole, aniline, or thiophene, and its concentration in the electrolyte is 0.1~0.35M; the protic acid is phytic acid or camphor sulfonic acid, and its concentration in the electrolyte is 0.42~0.5M.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: The conductive anti-corrosion coating material prepared by this invention has a double-layer anti-corrosion structure. The inner layer is an epoxy acrylic resin coating with ZIF-8 / GO / Phen material and carbon nanotubes as fillers. The corrosion path is extended by the "maze effect" of graphene oxide, while carbon nanotube (CNT) doping effectively enhances the conductivity of the coating and assists the electrodeposition of polyaniline or polypyrrole in the outer layer. The double-layer structure provides a good physical barrier for the substrate and achieves passive protection.

[0015] The outer conductive polymer provides anodic protection (preferential oxidation) through anodic protection and corrosion inhibition by doped anions (such as camphor sulfonic acid and phytic acid). The conductive polymer's conductive network promotes electron transfer, inhibits localized galvanic corrosion, and enhances the coating's durability in harsh acidic environments. The inner ZIF-8 / GO / Phen layer uses ZIF-8-grown graphene oxide as a carrier, achieving corrosion inhibitor (1,10-phenanthroline) loading through π-π stacking and coordination bonds, ensuring that the corrosion inhibitor does not leak prematurely. When the acidic corrosion environment triggers the pH-responsive characteristics of ZIF-8, the ZIF-8 / GO / Phen material directionally releases the corrosion inhibitor and forms a red complex with Fe²⁺ for self-diagnosis, while simultaneously forming a passivation film for self-repair. The corrosion inhibitor can also chelate and dissolve metal ions, reducing membrane electrode poisoning, while the graphene oxide barrier layer inhibits metal ion dissolution. Through the synergistic effect of the inner and outer layers, active protection of the substrate is achieved in acidic environments.

[0016] The conductive and corrosion-resistant coating material prepared by this invention possesses a multi-mechanism synergistic anti-corrosion function, enabling long-term corrosion protection. It shows promising application prospects in acidic working environments such as chemical equipment corrosion protection (strong acid medium environment) and flue gas desulfurization systems (acid gas + condensate environment). Due to the coating's excellent conductivity, it has even greater advantages in the field of fuel cell metal bipolar plates. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 These are Nyquist images obtained after EIS testing of the coatings in Examples 1-4 of Experiment 1 of this invention.

[0018] Figure 2 This is a Nyquist image of the coating in Example 3 of Experiment 2 of this invention after long-term (30d) service.

[0019] Figure 3 This is a Nyquist image of the coating in Example 5 of Experiment 3 of this invention after long-term (30 days) service.

[0020] Figure 4 These are the potentiodynamic polarization curves of the coatings in Examples 1-5 of Experiment 4 of this invention.

[0021] Figure 5 These are the test results of the coating self-healing experiment in Examples 3 (a1, b1, c1) and Example 5 (a2, b2, c2) of Experiment 5 of this invention.

[0022] Figure 6 These are electron microscope images of the coating morphology of Comparative Examples 1 (d), 2 (e), 3 (f), and 6 (g) after 60 days of service in an acidic environment in Experiment 6 of this invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Materials used in this invention and their sources: The metal substrate is 304 stainless steel, from Wenzhou Tehong Special Materials Co., Ltd.; the graphene oxide is from Zhongke Yueda (Shanghai) Materials Technology Co., Ltd., with an average sheet diameter of ≤300nm; the epoxy acrylate resin is from Foshan Wanxia New Materials Technology Co., Ltd.; the carbon nanotube dispersion is from Aokexier Trading (Shenzhen) Co., Ltd.; and the carbon nanotubes are from Shanghai McLean Biochemical Technology Co., Ltd., with an average diameter of 20nm. Example

[0025] Step 1: Dissolve 1g of zinc acetate dihydrate in 20mL of methanol to obtain a zinc acetate dihydrate / methanol solution; dissolve 3g of dimethylimidazole in 30mL of methanol to obtain a dimethylimidazole / methanol solution; add 10mL of graphene oxide dispersion (concentration of graphene oxide dispersion is 3mg / mL) to the zinc acetate dihydrate / methanol solution and stir for 1h; continue to add dimethylimidazole / methanol solution, and react in a water bath at 20℃ for 24h to obtain a reaction solution; centrifuge the reaction solution for 10min (8000r / min) until the supernatant is colorless and transparent, separate the solid and liquid and collect the solid precipitate, wash it three times with methanol, place it in a vacuum oven to dry for 12h, and grind it in a mortar to obtain gray-black ZIF-8 / GO nanoparticles; Step 2: 1,10-phenanthroline and ZIF-8 / GO nanoparticles were added to methanol sequentially and stirred to obtain a dispersion solution, wherein the content of 1,10-phenanthroline was 30 mg / mL and the content of ZIF-8 / GO was 5 mg / mL; the dispersion solution was allowed to stand at 20℃ under vacuum for 6 h, centrifuged until the supernatant was colorless and transparent, solid-liquid separation was performed and the solid precipitate was collected, washed with methanol, wrapped in tin foil and dried at 50℃ to obtain ZIF-8 / GO / Phen material; Step 3: Mix the carbon nanotube dispersion with epoxy acrylate resin, stir for 3 minutes, then add carbon nanotubes and ZIF-8 / GO / Phen material, and continue stirring for 24 hours to obtain a conductive anti-corrosion coating; the concentration of the carbon nanotube dispersion is 0.3 wt.%; in the conductive anti-corrosion coating, the weight ratio of carbon nanotube dispersion, epoxy acrylate resin, and carbon nanotubes is 13:4.5:0.28, and the content of ZIF-8 / GO / Phen material is 0.5 wt.%. Step 4: Select a metal substrate for surface pretreatment. First, use sandpaper to sand in one direction to remove the oxide layer on the surface, then polish it, and finally rinse it with deionized water and anhydrous ethanol and dry it for later use. Apply the conductive anti-corrosion coating to the surface of the metal substrate using the roller coating method, and dry and cure it at 55°C for 24 hours to form an anti-corrosion coating. Example

[0026] Step 1: Dissolve 1.53g of zinc acetate dihydrate in 20mL of methanol to obtain a zinc acetate dihydrate / methanol solution; dissolve 6.03g of dimethylimidazole in 30mL of methanol to obtain a dimethylimidazole / methanol solution; add 10mL of graphene oxide dispersion (concentration of graphene oxide dispersion is 4mg / mL) to the zinc acetate dihydrate / methanol solution and stir for 1h; continue to add dimethylimidazole / methanol solution, and react in a water bath at 25℃ for 24h to obtain a reaction solution; centrifuge the reaction solution for 10min (8000r / min) until the supernatant is colorless and transparent, separate the solid and liquid and collect the solid precipitate, wash it three times with methanol, place it in a vacuum oven to dry for 12h, and grind it in a mortar to obtain gray-black ZIF-8 / GO nanoparticles; Step 2: 1,10-phenanthroline and ZIF-8 / GO nanoparticles were added to methanol sequentially and stirred to obtain a dispersion solution, wherein the content of 1,10-phenanthroline was 50 mg / mL and the content of ZIF-8 / GO was 10 mg / mL; the dispersion solution was allowed to stand at 25℃ under vacuum for 8 h, centrifuged until the supernatant was colorless and transparent, solid-liquid separation was performed and the solid precipitate was collected, washed with methanol, wrapped in tin foil and dried at 60℃ to obtain ZIF-8 / GO / Phen material; Step 3: Mix the carbon nanotube dispersion with epoxy acrylate resin, stir for 4 minutes, then add carbon nanotubes and ZIF-8 / GO / Phen material, and continue stirring for 24 hours to obtain a conductive anti-corrosion coating; the concentration of the carbon nanotube dispersion is 0.4 wt.%; in the conductive anti-corrosion coating, the weight ratio of carbon nanotube dispersion, epoxy acrylate resin, and carbon nanotubes is 15.2:5.1:0.3, and the content of ZIF-8 / GO / Phen material is 1 wt.%. Step 4: Select a metal substrate for surface pretreatment. First, use sandpaper to sand in one direction to remove the oxide layer on the surface, then polish it, and finally rinse it with deionized water and anhydrous ethanol and dry it for later use. Apply the conductive anti-corrosion coating to the surface of the metal substrate using the roller coating method, and dry and cure it at 60°C for 24 hours to form an anti-corrosion coating. Example

[0027] Step 1: Dissolve 1.98g of zinc acetate dihydrate in 20mL of methanol to obtain a zinc acetate dihydrate / methanol solution; dissolve 7.38g of dimethylimidazole in 30mL of methanol to obtain a dimethylimidazole / methanol solution; add 10mL of graphene oxide dispersion (concentration of graphene oxide dispersion is 4mg / mL) to the zinc acetate dihydrate / methanol solution and stir for 1h; continue to add dimethylimidazole / methanol solution, and stir the reaction in a water bath at 25℃ for 24h to obtain a reaction solution; centrifuge the reaction solution for 10min (8000r / min) until the supernatant is colorless and transparent, separate the solid and liquid and collect the solid precipitate, wash it three times with methanol, place it in a vacuum oven to dry for 12h, and grind it in a mortar to obtain gray-black ZIF-8 / GO nanoparticles; Step 2: 1,10-phenanthroline and ZIF-8 / GO nanoparticles were added to methanol sequentially and stirred to obtain a dispersion solution, wherein the content of 1,10-phenanthroline was 50 mg / mL and the content of ZIF-8 / GO was 10 mg / mL; the dispersion solution was allowed to stand at 25℃ under vacuum for 8 h, centrifuged until the supernatant was colorless and transparent, solid-liquid separation was performed and the solid precipitate was collected, washed with methanol, wrapped in tin foil and dried at 60℃ to obtain ZIF-8 / GO / Phen material; Step 3: Mix the carbon nanotube dispersion with epoxy acrylate resin, stir for 4 minutes, then add carbon nanotubes and ZIF-8 / GO / Phen material, and continue stirring for 24 hours to obtain a conductive anti-corrosion coating; the concentration of the carbon nanotube dispersion is 0.4 wt.%; in the conductive anti-corrosion coating, the weight ratio of carbon nanotube dispersion, epoxy acrylate resin, and carbon nanotubes is 15.2:5.1:0.3, and the content of ZIF-8 / GO / Phen material is 1.5 wt.%. Step 4: Select a metal substrate for surface pretreatment. First, use sandpaper to sand in one direction to remove the oxide layer on the surface, then polish it, and finally rinse it with deionized water and anhydrous ethanol and dry it for later use. Apply the conductive anti-corrosion coating to the surface of the metal substrate using the roller coating method, and dry and cure it at 60°C for 24 hours to form an anti-corrosion coating. Example

[0028] Step 1: Dissolve 2g of zinc acetate dihydrate in 20mL of methanol to obtain a zinc acetate dihydrate / methanol solution; dissolve 7.5g of dimethylimidazole in 30mL of methanol to obtain a dimethylimidazole / methanol solution; add 10mL of graphene oxide dispersion (concentration of graphene oxide dispersion is 5mg / mL) to the zinc acetate dihydrate / methanol solution and stir for 1h; continue to add dimethylimidazole / methanol solution, and react in a water bath at 30℃ for 24h to obtain a reaction solution; centrifuge the reaction solution for 10min (8000r / min) until the supernatant is colorless and transparent, separate the solid and liquid and collect the solid precipitate, wash it three times with methanol, place it in a vacuum oven to dry for 12h, and grind it in a mortar to obtain gray-black ZIF-8 / GO nanoparticles; Step 2: 1,10-phenanthroline and ZIF-8 / GO nanoparticles were added to methanol sequentially and stirred to obtain a dispersion solution, wherein the content of 1,10-phenanthroline was 60 mg / mL and the content of ZIF-8 / GO was 20 mg / mL; the dispersion solution was allowed to stand at 30℃ under vacuum for 10 h, centrifuged until the supernatant was colorless and transparent, solid-liquid separation was performed and the solid precipitate was collected, washed with methanol, wrapped in tin foil and dried at 60℃ to obtain ZIF-8 / GO / Phen material; Step 3: Mix the carbon nanotube dispersion with epoxy acrylate resin, stir for 5 minutes, then add carbon nanotubes and ZIF-8 / GO / Phen material, and continue stirring for 24 hours to obtain a conductive anti-corrosion coating; the concentration of the carbon nanotube dispersion is 0.5 wt.%; in the conductive anti-corrosion coating, the weight ratio of carbon nanotube dispersion, epoxy acrylate resin, and carbon nanotubes is 16:6:0.32, and the content of ZIF-8 / GO / Phen material is 2.0 wt.%. Step 4: Select a metal substrate for surface pretreatment. First, use sandpaper to sand in one direction to remove the oxide layer on the surface, then polish it, and finally rinse it with deionized water and anhydrous ethanol and dry it for later use. Apply the conductive anti-corrosion coating to the surface of the metal substrate using the roller coating method, and dry and cure it at 65°C for 24 hours to form an anti-corrosion coating.

[0029] Experiment 1: Performance tests were conducted on the coatings prepared in Examples 1-4. The experimental results are as follows: Figure 1 As shown.

[0030] The working environment of a PEMFC metal bipolar plate was simulated, and corrosion resistance tests were conducted using a 0.1 mol / L hydrochloric acid solution. Electrochemical impedance spectroscopy (EIS) was used to test the corrosion resistance of the metal under coating protection. The test method was as follows: a stable open-circuit voltage was used as the reference, the amplitude was set to 10 mV, and the frequency range was 0.01 Hz-100 kHz. A larger capacitive arc radius in the high-frequency region of EIS indicates higher polarization resistance, enhanced passivation film density, and stronger barrier properties against corrosive media, resulting in stronger coating corrosion resistance.

[0031] from Figure 1 It can be seen that the ZIF-8 / GO / Phen material content increases in Examples 1 to 4, and the capacitive arc resistance shows a development trend of first being large and then small. Among them, the conductive corrosion coating of Example 3 (1.5wt% ZIF-8 / GO / Phen-EA composite coating) has better uniformity and dispersion, the largest capacitive arc resistance, and the strongest anti-corrosion ability.

[0032] Experiment 2: The anti-corrosion performance of the anti-corrosion coating prepared in Example 3 was tested over a long period (30 days). The experimental results are as follows: Figure 2 As shown.

[0033] from Figure 2 It can be seen that the capacitive arc of the coating decreases rapidly, indicating that the coating is corroded, the polarization resistance decreases, and the corrosion resistance declines. After 48 hours, the capacitive arc of the coating steadily increases. The graphene oxide particles block the intrusion of corrosive particles and coordinate the formation of a passivation film by the corrosion inhibitor, improving the corrosion resistance of the coating and increasing the polarization resistance. From the long-term service performance, the capacitive arc of the coating shows a positive correlation with time, gradually reaching the maximum polarization resistance.

[0034] Experiment 3: Based on Example 3, a conductive polymer was deposited as Example 5. The long-term (30d) anti-corrosion performance of the composite coating in Example 5 was tested according to the method in Experiment 1. The experimental results are as follows: Figure 3 As shown. Example

[0035] The metal substrate was pretreated by first sanding in one direction to remove the oxide layer, followed by polishing, and finally rinsing with deionized water and anhydrous ethanol and drying. The conductive anti-corrosion coating prepared in Example 3 was applied to the metal substrate surface using a roller coating method and dried and cured at 60°C for 24 hours to form an anti-corrosion coating. A constant current deposition method was used, with a mixed solution of aniline monomer and phytic acid as the electrolyte. The concentration of aniline monomer in the electrolyte was 0.1M, and the concentration of phytic acid was 0.42M. Using the metal substrate coated with the anti-corrosion coating as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode, the conductive polymer was deposited on the surface of the anti-corrosion coating at a deposition current density of 1 mA / cm². 2 After deposition is complete, rinse the surface with deionized water and dry to obtain a conductive and corrosion-resistant coating.

[0036] from Figure 3 It can be seen that during long-term service, the capacitive arc resistance of the coating steadily increases and the polarization resistance improves, indicating that the coating has excellent anti-corrosion performance. After the polyaniline on the coating surface comes into contact with the corrosive medium, an oxidation-reduction reaction occurs, which promotes the formation of a passivation film, blocks the intrusion of corrosive particles, realizes active anti-corrosion and self-repair functions, and maintains high stability.

[0037] Experiment 4: Potentiodynamic polarization tests were performed on the coatings from Examples 1-5. Under stable open-circuit potential conditions, the voltage scan rate was set to 0.33 mV / s, and the scan range was OCP ± 0.5 V. Data fitting was performed using Nova software via Tafel extrapolation to obtain the corresponding corrosion characteristic parameters, and the conductive corrosion protection performance was analyzed. The experimental results are as follows: Figure 4 As shown.

[0038] from Figure 4 It can be seen that the composite coating (1.5wt% CPs / ZIF-8 / GO / Phen-EA) in Example 5 has the highest self-corrosion potential and the lowest corrosion current density, indicating that the coating has the best and most stable anti-corrosion properties after the introduction of conductive polymer, while also having better conductivity.

[0039] Experiment 5: To further illustrate the superior self-healing properties of the conductive anti-corrosion coating material prepared in this invention, 5mm scratches were artificially applied to the coating surfaces of Examples 3 and 5, ensuring the coating was broken and the scratches were smooth and free of other textures. An EIS test was conducted for one week using an electrochemical workstation (parameters the same as in Experiment 1) to investigate its self-healing characteristics. The experimental results are as follows: Figure 5 As shown.

[0040] from Figure 5 As can be seen from a1, b1, and c1, the capacitive arc of the coating in Example 3 decreased rapidly within 0-12 hours after the scratch, the polarization resistance decreased, and the corrosion process accelerated. The increase in the coating's OCP highlights the barrier and corrosion-inhibiting properties of the coating's anti-corrosion particles, reducing the corrosion rate. In the subsequent 24-120 hours, the capacitive arc of the coating increased rapidly, and the OCP gradually increased. At 120 hours, the coating modulus (|Z|) in the low-frequency region... 0.01Hz The resistance in the coating reaches its highest level and tends to stabilize. The blocking effect of GO and the release of corrosion inhibitors induce the formation of a passivation film, increasing the polarization resistance and hindering the corrosion process. Although the resistance in the high-frequency region is weaker than in the initial test, the resistance in the low-frequency region shows a significant increase and exhibits extremely strong stability. As the test progresses, the capacitive arc of the coating slightly increases and remains stable, inhibiting corrosion. This indicates that the anti-corrosion performance of the coating has a time-dependent effect. As the anti-corrosion particles take effect, the conductive anti-corrosion performance of the coating enhances and tends to stabilize. Under scratch conditions, it possesses a self-healing effect, inhibiting the corrosion process.

[0041] from Figure 5(a2, b2, c2) It can be seen that after scratching, the composite coating of Example 5 rapidly increases its capacitive arc resistance within 0-12 hours. The polyaniline molecules on the coating surface directly contact the corrosive medium, blocking the penetration of corrosive particles, promoting the formation of a passivation film on the metal surface, increasing the polarization resistance, and reducing the corrosion rate. The decrease in OCP and the reduction in corrosion potential highlight the improved conductivity of the coating. After 12 hours, the coating's capacitive arc resistance steadily increases. In the high-frequency region, it blocks corrosive particles, extends the corrosion path, promotes the formation of a passivation film, and increases the polarization resistance; in the low-frequency region, the increased resistance highlights the strong stability of the coating. The fluctuation of OCP highlights the improved conductivity and the active anti-corrosion mechanism of the anti-corrosion particles. Among them, the coating modulus |Z| 0.01Hz It reaches its maximum value at 24 hours, and then the resistance fluctuates and stabilizes close to the highest resistance value.

[0042] A comprehensive analysis of the two coatings in Examples 3 and 5, combined with Figure 5 (a1, a2, b1, b2) It can be seen that the polarization resistance of the coating in Example 3 is two orders of magnitude higher than that of the coating in Example 5, which directly reflects that the introduction of polyaniline greatly improves the conductivity of the coating. The increasing trend of capacitive arc resistance reflects the excellent anti-corrosion performance of the coating in Example 5, and the introduction of polyaniline gives the coating a faster active anti-corrosion self-healing effect. According to Figure 5 (c1, c2) It can be seen that the corrosion potential of the coating in Example 5 is higher than that of the coating in Example 3, which shows excellent anti-corrosion performance and inhibits the corrosion process.

[0043] Experiment 6: A 0.1 mol / L hydrochloric acid solution was used to simulate the acidic corrosion environment of a metal bipolar plate. The conductive anti-corrosion coating materials prepared in Examples 3, 6, Comparative Example 1, and Comparative Example 2 were subjected to service in the corrosive environment for 60 days. The morphology of the coatings was observed using a scanning electron microscope. Figure 6 As shown. Example

[0044] The metal substrate was pretreated by first sanding in one direction to remove the oxide layer, followed by polishing, and finally rinsing with deionized water and anhydrous ethanol and drying. The conductive anti-corrosion coating prepared in Example 3 was applied to the surface of the metal substrate using a roller coating method and dried and cured at 60°C for 24 hours to form an anti-corrosion coating. The constant current deposition method used a mixed solution of pyrrole and camphor sulfonic acid as the electrolyte, with the metal substrate coated with the anti-corrosion coating as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The deposition current density was 2 mA / cm². 2 The concentration of pyrrole in the electrolyte is 0.35M; the concentration of camphor sulfonic acid in the electrolyte is 0.5M.

[0045] from Figure 6As can be seen, after 60 days of service in an acidic environment, a large number of visible micropores appeared on the surface of coating (d) in Comparative Example 1. This microstructural degradation accelerates the penetration of corrosive media, ultimately leading to substrate corrosion. In Comparative Example 2, after the introduction of graphene oxide, coating (e) showed only a few micropores on its surface, indicating that the addition of graphene oxide improved the coating's density and delayed the contact between the corrosive media and the metal surface. In contrast, coating (f) in Example 3 maintained a relatively dense microstructure with very few micropores even after long-term immersion. This phenomenon is attributed to the corrosion inhibitor 1,10-phenanthroline forming a complex with Fe²⁺ generated by localized corrosion, thereby inhibiting the corrosion process. In Example 6, after the introduction of a conductive polypyrrole outer layer, coating (g) exhibited a typical spherical cauliflower-like rough three-dimensional structure with no obvious micropores, indicating its excellent physical barrier effect against corrosive media.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0047] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a conductive anti-corrosion coating material with self-healing function, characterized in that: Includes the following steps: Step 1: After mixing zinc acetate dihydrate / methanol solution and graphene oxide dispersion, dimethylimidazole / methanol solution was added, and the mixture was stirred in a water bath at 20~30℃ for 24h to obtain a reaction solution. The reaction solution was centrifuged until the supernatant was colorless and transparent, and the solid precipitate was collected after solid-liquid separation. After washing with methanol, vacuum drying, and grinding, gray-black ZIF-8 / GO nanoparticles were obtained. Step 2: Add 1,10-phenanthroline and ZIF-8 / GO nanoparticles sequentially to methanol and stir to obtain a dispersion solution; let the dispersion solution stand for 6-10 hours under vacuum at 20-30℃, centrifuge until the supernatant is colorless and transparent, separate the solid and liquid and collect the solid precipitate, wash the solid precipitate with methanol, wrap it in tin foil and dry it at 50-60℃ to obtain ZIF-8 / GO / Phen material; Step 3: Mix the carbon nanotube dispersion with epoxy acrylic resin, stir for 3-5 minutes, then add carbon nanotubes and ZIF-8 / GO / Phen material, and continue stirring for 24 hours to obtain a conductive anti-corrosion coating. Step 4: Select a metal substrate for surface pretreatment, apply conductive anti-corrosion coating to the surface of the metal substrate using a roller coating method, and heat-cur it to form an anti-corrosion coating. A conductive polymer was deposited onto the surface of the anti-corrosion coating using a constant current deposition method. After deposition, the surface was rinsed with deionized water and dried to obtain the conductive anti-corrosion coating material.

2. The method for preparing a conductive anti-corrosion coating material with self-healing function according to claim 1, characterized in that: In step 1, zinc acetate dihydrate / methanol solution, graphene oxide dispersion, and dimethylimidazole / methanol solution are mixed at a volume ratio of 2:1:3; wherein the concentration of zinc acetate dihydrate / methanol solution is 0.05~0.1g / mL, the concentration of graphene oxide dispersion is 3~5mg / mL, and the concentration of dimethylimidazole / methanol solution is 0.1~0.25g / mL.

3. The method for preparing a conductive anti-corrosion coating material with self-healing function according to claim 1, characterized in that: In step 2, the 1,10-phenanthroline content in the dispersion is 30~60 mg / mL, and the ZIF-8 / GO content is 5~20 mg / mL.

4. The method for preparing a conductive anti-corrosion coating material with self-healing function according to claim 1, characterized in that: In step 3, the concentration of carbon nanotube dispersion is 0.3~0.5 wt.%; the weight ratio of carbon nanotube dispersion, epoxy acrylate resin and carbon nanotubes in the conductive anticorrosive coating is (13~16):(4.5~6):(0.28~0.32); the content of ZIF-8 / GO / Phen material is 0.5~2.0 wt.% of the total weight of the conductive anticorrosive coating.

5. The method for preparing a conductive anti-corrosion coating material with self-healing function according to claim 1, characterized in that: In step 4, the surface pretreatment process of the metal substrate is as follows: first, use sandpaper to grind in one direction to remove the oxide layer on the surface, then perform polishing treatment, and finally rinse and dry with deionized water and anhydrous ethanol.

6. The method for preparing a conductive anti-corrosion coating material with self-healing function according to claim 1, characterized in that: In step 4, the thermosetting conditions are: drying and curing at 55~65℃ for 24 hours.

7. The method for preparing a conductive anti-corrosion coating material with self-healing function according to claim 1, characterized in that: In step 4, the constant current deposition method uses a mixed solution of conductive polymer monomer and protic acid as the electrolyte, a metal substrate with an anti-corrosion coating as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The deposition current density is 1~2 mA / cm². 2 .

8. The method for preparing a conductive anti-corrosion coating material with self-healing function according to claim 7, characterized in that: The conductive polymer monomer is any one of pyrrole, aniline, or thiophene, and its concentration in the electrolyte is 0.1~0.35M; the protic acid is phytic acid or camphor sulfonic acid, and its concentration in the electrolyte is 0.42~0.5M.

9. The conductive anti-corrosion coating material prepared by the preparation method according to any one of claims 1 to 8.

10. An application of the conductive anti-corrosion coating material as described in claim 9, characterized in that: Conductive and corrosion-resistant coating materials are used in metal bipolar plates of fuel cells.

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