Preparation method of anti-corrosion coating with double mechanisms of shielding barrier and corrosion inhibition

Abstract

The invention relates to a preparation method of an anticorrosive coating with double mechanisms of shielding, blocking and corrosion inhibition, which comprises the following steps: adding GO, ZnO powder and dopamine into deionized water, and carrying out ultrasonic dispersion to obtain a uniform solution; adding a Tris-HCl salt to initiate the polymerization of the dopamine; the substrate is ground and polished, and then the substrate is put into ethyl alcohol to be subjected to ultrasonic cleaning so as to remove surface impurities; drying by air blowing to remove the residual solvent on the surface of the substrate; mixing the composite particles into an epoxy resin solution; on this basis, a mixed solution is sprayed, and spraying parameters are controlled; and finally heating and curing. The graphene oxide and the zinc oxide are introduced into the epoxy resin coating, so that the corrosion resistance and the long-acting protection performance of the coating are improved. The GO sheet layer forms an effective barrier structure in the coating, permeation of corrosive ions can be obviously hindered, and the corrosion process is delayed; meanwhile, rich oxygen-containing functional groups of GO are beneficial to firm combination with a resin matrix, so that the coating is more compact, and the overall impact resistance of the coating is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coating preparation, and relates to a preparation method of an anti-corrosion coating with a dual mechanism of shielding barrier and corrosion inhibition. Specifically, it relates to a preparation method of an anti-corrosion coating that utilizes the physical shielding barrier effect of graphene oxide (GO) and the chemical corrosion inhibition effect of ZnO to achieve the dual mechanism of shielding barrier and corrosion inhibition. Background Art

[0002] Marine hulls are constantly exposed to humid and highly saline environments, making them extremely prone to corrosion. A large amount of chloride ions in seawater will accelerate the corrosion process of metals, gradually weakening the hull structure and even causing perforation. This not only threatens the safety and lifespan of the hull but may also lead to environmental pollution problems such as oil spills, resulting in huge economic losses and ecological damage. To address the issue of hull corrosion, the graphene oxide (GO) epoxy resin anti-corrosion coating has been widely used in marine anti-corrosion due to its good physical barrier performance. GO forms a "labyrinth effect" in the coating, effectively blocking the penetration of corrosive ions or molecules. However, the anti-corrosion effect of the GO coating is single, and its shielding ability gradually decreases over time.

[0003] To improve the deficiencies of the GO coating, introducing other functional fillers has become the focus of research. Among them, zinc oxide (ZnO) has attracted much attention due to its excellent chemical stability and corrosion inhibition. When cracks or damages appear in the coating, allowing the corrosive medium to come into contact with the metal substrate, ZnO can release Zn2+ ions, forming a protective oxide film on the metal surface and effectively slowing down corrosion. Therefore, adding ZnO to the GO coating is expected to achieve synergistic effects in long-term anti-corrosion of the coating to meet more demanding usage requirements. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical bottlenecks in the long-term effectiveness and corrosion resistance of existing marine hull anti-corrosion coatings, and to provide a preparation method of an anti-corrosion coating with a dual mechanism of shielding barrier and corrosion inhibition.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A preparation method of an anti-corrosion coating with a dual mechanism of shielding barrier and corrosion inhibition, the method comprising the following steps:

[0007] Step 1: Add 1 - 3 g of GO, 1 - 3 g of ZnO powder, and 6 - 8 g of dopamine to 20 - 70 mL of deionized water, and continuously ultrasonically disperse for 10 - 20 min to make it uniform; then add 0.1 - 0.3 g of Tris-HCl salt, and polymerize at 30 - 50 °C for 20 - 40 min to induce the polymerization of dopamine, thereby enhancing the adhesion and compatibility between GO and ZnO particles; wash, centrifuge, and then dry to obtain the composite particle powder;

[0008] Step 2: Polish the substrate, put the substrate into a solution for ultrasonic cleaning to remove surface impurities, and use air drying to remove the residual solvent;

[0009] Step 3: Add 5 - 7 g of epoxy resin and 2 - 3 g of curing agent into 5 - 7 g of organic solvent, stir for 10 - 12 min to fully dissolve them, and then add 1 - 2.5 g of composite particle powder obtained in Step 1, and mix evenly;

[0010] Step 4: Uniformly spray the mixture prepared in Step 3 onto the substrate treated in Step 2. After spraying, heat it at 100 - 120 °C for 1 - 3 h to form an anti - corrosion coating with dual mechanisms of shielding barrier and corrosion inhibition.

[0011] The dual - effect synergistic anti - corrosion mechanism of the present invention not only includes the barrier effect at the physical level, effectively increasing the penetration path of corrosive ions, but also innovatively introduces ZnO that can form Zn 2+ to form a protective film, realizing dual - effect anti - corrosion of physical chemistry.

[0012] Further, in Step 1, the particle size of the ZnO powder is 1 - 5 microns.

[0013] Further, in Step 1, the washing solution is deionized water or ethanol.

[0014] Further, in Step 1, the drying method is air drying or freeze - drying.

[0015] Further, in Step 1, polymerize at 40 °C for 30 min.

[0016] Further, Step 2 is specifically: Polish the substrate with 800 - mesh and 1000 - mesh sandpapers for 10 - 20 min in sequence, then put the substrate into 20 - 70 mL of solution for ultrasonic cleaning for 12 - 15 min to remove surface impurities; then, dry it in a blast oven at 60 - 80 °C for 20 - 30 min to remove the residual solvent.

[0017] Further, in Step 2, the substrate is one of low - carbon steel plate, alloy plate or aluminum plate.

[0018] Further, in Step 2, the solution is one of deionized water, ethanol or acetone.

[0019] Further, in Step 3, the organic solvent is one of ethyl acetate, butyl acetate or ethanol.

[0020] Further, in Step 4, the specific spraying conditions are: use an air pressure of 0.6 - 0.8 MPa, the spraying time is 8 - 10 min, and the spraying distance is 10 - 15 cm.

[0021] Compared with the prior art, the present invention has the following advantages: The present invention introduces graphene oxide (GO) and zinc oxide (ZnO) into the epoxy resin coating to improve the anti-corrosion and long-term protection performance of the coating. The GO sheets form an effective barrier structure in the coating, which can significantly hinder the penetration of corrosive ions and delay the corrosion process; at the same time, the rich oxygen-containing functional groups of GO contribute to the firm bonding with the resin matrix, making the coating more dense and improving its overall impact resistance. When the coating is damaged or corrosive media invade, ZnO can release Zn2+ to form a protective oxide film on the metal surface, effectively inhibiting the spread of corrosion and further enhancing the corrosion resistance and long-term protection ability of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the SEM image of GO / ZnO composite particles;

[0023] Figure 2 It is the EDS spectrum corresponding to C in GO / ZnO composite particles;

[0024] Figure 3 It is the EDS spectrum corresponding to O in GO / ZnO composite particles;

[0025] Figure 4 It is the EDS spectrum corresponding to Zn in GO / ZnO composite particles;

[0026] Figure 5 It is the FTIR spectrum of GO / ZnO composite particles;

[0027] Figure 6 It is the change diagram of electrochemical impedance spectroscopy before and after corrosion of pure epoxy coating (Nyquist diagram);

[0028] Figure 7 It is the change diagram of electrochemical impedance spectroscopy before and after corrosion of GO / ZnO epoxy coating (Nyquist diagram). DETAILED DESCRIPTION OF THE INVENTION

[0029] The technical solutions of the present invention will be further described below in conjunction with the drawings and embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0030] The present invention introduces zinc oxide (ZnO) and graphene oxide (GO) into an epoxy resin matrix to enhance the anti-corrosion performance of the coating. When the hull surface is damaged, ZnO can release Zn2+ to form a protective oxide film on the metal surface, effectively inhibiting the spread of corrosion. At the same time, the shielding effect and chemical inertness of GO can block the penetration of corrosive media, thereby improving the corrosion resistance of the coating. The present invention synergistically applies the characteristics of GO and ZnO to effectively combine the functions of anti-corrosion, long-term protection, and self-healing, enabling the coating to possess excellent anti-corrosion and long-term protection performance.

[0031] Example 1:

[0032] A method for preparing an anti-corrosion coating with a dual mechanism of shielding barrier and corrosion inhibition, the method comprising the following steps:

[0033] Step 1: Add 2 g of GO, 2 g of ZnO powder, and 7 g of dopamine to 50 mL of deionized water, and ultrasonically disperse for 15 min to make it uniform. Subsequently, add 0.1 g of Tris-HCl salt and polymerize at 40 °C for 30 min to induce the polymerization of dopamine, thereby enhancing the adhesion and compatibility between GO and ZnO ceramic particles. Wash with deionized water, centrifuge, and then freeze-dry to obtain a composite particle powder.

[0034] Step 2: Polish the steel plate substrate with 800-mesh and 1000-mesh sandpapers for 10 min in sequence, then place the substrate in 50 mL of ethanol and ultrasonically clean for 13 min to remove surface impurities. Then, dry in a forced-air oven at 80 °C for 30 min to remove residual solvents.

[0035] Step 3: Add 5 g of epoxy resin and 2.5 g of curing agent to 5 g of organic solvent, stir for 10 min to fully dissolve, and then add 2 g of the composite particle powder obtained in Step 1 and mix evenly.

[0036] Step 4: Uniformly spray 30 mL of the mixture prepared in Step 3 onto a 50 cm x 50 cm steel plate substrate treated in Step 2. During the spraying process, use an air pressure of 0.8 MPa, the spraying time is 8 minutes, and the spraying distance is about 15 cm. After spraying, heat at 120 °C for 3 h to form an anti-corrosion coating with a dual mechanism of shielding barrier and corrosion inhibition.

[0037] Figures 1 to 4SEM photograph and EDS spectrum of GO / ZnO composite particles. GO has a lamellar structure and is rich in a large number of polar groups, which easily leads to agglomeration. However, when ZnO particles adhere to the surface of GO, the lamellar structure of GO uniformly wrapping ZnO particles weakens. From the EDS spectrum analysis of GO / ZnO composite particles, it can be observed that ZnO is uniformly distributed on the surface of GO in the form of particles, and this uniform coverage reduces the polar groups on the surface of GO, effectively suppressing the occurrence of agglomeration problems.

[0038] Figure 5 is the FTIR spectrum of GO / ZnO composite particles. In ZnO, 1616 cm -1 is the characteristic absorption peak of Zn-O; in GO / ZnO composite particles, 2932 cm -1 is the characteristic peak of the stretching vibration of C-H, and 1080 cm -1 is the characteristic peak of the bending vibration of C-O, and 3431 cm -1 is the characteristic peak of O-H; the characteristic absorption peak of Zn-O also appears in GO / ZnO composite particles. These results indicate that ZnO has successfully adhered to the surface of the GO lamellar structure, and GO / ZnO composite particles have been successfully prepared.

[0039] The corrosion degree of GO / ZnO composite particle epoxy coatings and pure epoxy coatings in a corrosive environment was monitored by electrochemical impedance spectroscopy (EIS) in the frequency range of 10 5 -10 -2 Hz. The corrosive environment was immersion in 5 wt.% NaCl solution for 30 days. From Figure 6 and Figure 7 it can be seen that the Nyquist plots of GO / ZnO composite particle epoxy coatings and pure epoxy coatings both show that the arc radius gradually shrinks with the immersion time. This is because the corrosive medium (Cl - , H 2 O) gradually penetrates and damages the coating more deeply with the increase of time, resulting in a gradual decline in the barrier performance of the coating.

[0040] After 30 days of corrosion, the impedance arc of the Nyquist plot of the pure epoxy coating changes from one to two, indicating that at this time the corrosive medium has diffused to the interface between the epoxy resin and the steel substrate, and the metal substrate has corroded. However, for the GO / ZnO composite particle epoxy coating, the impedance arc of the Nyquist plot is still one, and the radius shrinkage trend is lower than that of the pure epoxy coating.

[0041] This is because the GO sheets form an effective barrier structure in the coating, which can significantly hinder the penetration of corrosive ions and delay the corrosion process. At the same time, the abundant oxygen-containing functional groups of GO contribute to the strong bonding with the resin matrix, making the coating more dense and improving its overall impact resistance. When the coating is damaged or corrosive media invade, ZnO can release Zn2+ to form a protective oxide film on the metal surface, effectively inhibiting the spread of corrosion and further enhancing the corrosion resistance and long-term protection ability of the coating. As a result, the barrier performance of the GO / ZnO composite particle epoxy coating is higher than that of the pure epoxy coating.

[0042] Example 2:

[0043] Step 1: Add 3 g of GO, 3 g of ZnO powder and 7 g of dopamine into 60 mL of deionized water, and ultrasonically disperse for 20 min to make it uniform. Then add 0.2 g of Tris-HCl salt and polymerize at 40 °C for 30 min to induce the polymerization of dopamine, thereby enhancing the adhesion and compatibility between GO and ZnO ceramic particles; wash with ethanol, centrifuge and then dry in a blast dryer to obtain the composite particle powder.

[0044] Step 2: Polish the steel plate substrate with 800-mesh and 1000-mesh sandpapers for 20 min in sequence, and then put the substrate into 60 mL of ethanol and ultrasonically clean for 15 min to remove surface impurities. Then, dry in a blast oven at 80 °C for 30 min to remove the residual solvent.

[0045] Step 3: Add 7 g of epoxy resin and 3 g of curing agent into 7 g of organic solvent, stir for 12 min to fully dissolve, and then add 2.5 g of the composite particle powder obtained in Step 1 and mix evenly.

[0046] Step 4: Spray 30 mL of the mixed solution prepared in Step 3 evenly onto the 50 cm x 50 cm steel plate substrate treated in Step 2. During the spraying process, use an air pressure of 0.8 MPa, the spraying time is 10 minutes, and the spraying distance is about 15 cm. After spraying, heat at 120 °C for 3 h to form an anti-corrosion coating with dual mechanisms of shielding barrier and corrosion inhibition.

[0047] Through electrochemical impedance spectroscopy (EIS) in the frequency range of 10 4 -10 -2 Hz, the corrosion degree of the GO / ZnO composite particle epoxy coating in the corrosion environment was monitored. The corrosion environment was immersion in 5.5 wt.% NaCl solution for 30 days. The Nyquist diagrams of the GO / ZnO composite particle epoxy coating all showed that the arc radius gradually shrank with the immersion time. This is because the corrosion media (Cl - , H 2 O) gradually penetrated and damaged the coating more deeply with the increase of time, resulting in a gradual decrease in the barrier performance of the coating.

[0048] After 30 days of corrosion, the impedance arc of the Nyquist plot of the pure epoxy coating changes from one to two, indicating that the corrosive medium has diffused to the interface between the epoxy resin and the steel substrate, and the metal substrate has corroded. However, for the GO / ZnO composite particle epoxy coating, the impedance arc of the Nyquist plot remains one, and the radius shrinkage trend is lower than that of the pure epoxy coating.

[0049] The dual-effect synergistic anti-corrosion mechanism of the present invention includes both a physical barrier effect, effectively increasing the penetration path of corrosive ions, and innovatively introducing ZnO that can form Zn 2+ to form a protective film, achieving dual-effect anti-corrosion of physical chemistry.

Claims

1. A method for preparing an anticorrosive coating having dual mechanisms of shielding, blocking and corrosion inhibition, characterized in that: The method comprises the following steps: Step 1: add 1-3g GO, 1-3g ZnO powder and 6-8g dopamine into 20-70mL deionized water, and disperse them uniformly by continuous ultrasonication; then add 0.1-0.3g Tris-HCl salt, polymerize at 30-50°C for 20-40min, wash, centrifuge and dry to obtain composite particle powder; Step 2: polishing the substrate, placing the substrate in a solution for ultrasonic cleaning to remove surface impurities, and air drying to remove residual solvent; Step 3: Add 5-7g of epoxy resin and 2-3g of curing agent into 5-7g of organic solvent, stir to fully dissolve, then add 1-2.5g of composite particle powder obtained in step 1, and mix well; Step 4: spray the mixed solution obtained in step 3 evenly onto the substrate treated in step 2. After spraying, heat at 100-120° C. for 1-3 hours to form an anti-corrosion coating with dual mechanisms of shielding, barrier and corrosion inhibition.

2. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 1, characterized in that: In step 1, the particle size of the ZnO powder is 1-5 microns.

3. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 1, characterized in that: In step 1, the washing solution is deionized water or ethanol.

4. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 1, characterized in that: In step 1, the drying method is air drying or freeze drying.

5. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 1, characterized in that: In step 1, polymerization was carried out at 40°C for 30 min.

6. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 1, characterized in that: The step 2 specifically comprises: polishing the substrate with 800-mesh and 1000-mesh sandpapers for 10-20 minutes, then placing the substrate in 20-70 mL of solution for ultrasonic cleaning for 12-15 minutes to remove surface impurities; and then drying in a 60-80° C. forced air oven for 20-30 minutes to remove residual solvent.

7. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 6, characterized in that: In step 2, the substrate is one of a low-carbon steel plate, an alloy plate or an aluminum plate.

8. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 6, characterized in that: In step 2, the solution is one of deionized water, ethanol or acetone.

9. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 1, characterized in that: In step 3, the organic solvent is one of ethyl acetate, butyl acetate or ethanol.

10. The method for preparing the anticorrosive coating having the dual functions of shielding, blocking and corrosion inhibition according to claim 1, characterized in that: In step 4, the specific conditions of the spraying are: using 0.6-0.8MPa air pressure, spraying time is 8-10min, and spraying distance is 10-15cm.

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