Preparation method of hydrotalcite modified fluorinated graphene corrosion-resistant self-repairing coating

Abstract

The application discloses a preparation method of a hydrotalcite modified fluorinated graphene corrosion-resistant self-repairing coating, and specifically comprises the following steps: step 1, cleaning the surface of a substrate to be treated; step 2, adding fluorinated graphene into an ethylene glycol aqueous solution, ultrasonic stirring and dispersing to obtain a solution A; dissolving Zn(NO3)2.6H2O and Al(NO3)3.9H2O in water to prepare a solution B; dissolving a corrosion inhibitor in water to obtain a solution C; then, mixing the solution A, the solution B and the solution C to obtain FG@LDH powder; step 3, mixing the FG@LDH powder prepared in step 2 with n-butanol and dimethylbenzene, then adding epoxy resin, mixing, ball milling, uniformly mixing the ball-milled product with a polyamide curing agent, coating on the surface of the substrate to be treated, and curing to obtain the coating.

Description

Technical Field

[0001] This invention relates to the field of heavy-duty anti-corrosion coatings for marine environments, specifically to a method for preparing a corrosion-resistant self-healing coating made of hydrotalcite-modified fluorinated graphene. Background Technology

[0002] The application of organic coatings in marine equipment is an important means of protecting metal structures from corrosion and environmental erosion. In the marine environment, due to factors such as the high salinity and humidity of seawater, as well as biological adhesion, metal materials are prone to corrosion, thus affecting their performance and lifespan. Therefore, developing efficient and durable anti-corrosion coatings is crucial to ensuring the safety and reliability of marine equipment.

[0003] Fluorinated graphene, an advanced nanomaterial, is a derivative obtained by fluorination of graphene. Through the fluorination process, some carbon atoms change from their original spline state to a non-spline state. 2 Hybrid state transitions to sp 3 Hybridization not only preserves the original large-sheet two-dimensional planar structure of graphene, but also introduces new CF bonds, endowing the material with a series of excellent properties. These properties make fluorinated graphene show a broader application prospect than ordinary graphene in fields such as corrosion resistance and wear resistance. However, despite the many advantages brought by fluorinated graphene, there are still problems in practical applications. Because the synthesis process of fluorinated graphene is relatively complex and requires the use of specific chemical reagents for fluorination, the cost of raw materials increases, limiting its large-scale application. In addition, even the best coatings may be damaged during actual service due to impacts, scratches, etc. Once the coating is damaged, moisture and oxygen may penetrate into the metal surface, leading to accelerated local corrosion and ultimately affecting the corrosion resistance and service life of the entire structure. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a method for preparing a corrosion-resistant and self-healing coating of hydrotalcite-modified fluorinated graphene. This method can significantly reduce the cost of fluorinated graphene while ensuring that the resulting coating possesses long-term high corrosion resistance and self-healing properties. This facilitates long-term protection of the metal substrate by the coating, thereby solving the problems of high cost of fluorinated graphene and accelerated local corrosion caused by coating damage in existing technologies.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for preparing a corrosion-resistant self-healing coating of hydrotalcite-modified fluorinated graphene, the specific steps of which are as follows:

[0007] Step 1: Clean the surface of the substrate to be treated;

[0008] Step 2: Fluorinated graphene is added to an ethylene glycol aqueous solution and ultrasonically stirred to disperse it, obtaining solution A. The concentration of fluorinated graphene in solution A is 0.4 mg / mL to 2.0 mg / mL, and the volume ratio of ethylene glycol to water is (1-3):(1-3). Zn(NO3)2·6H2O and Al(NO3)3·9H2O are dissolved in water to prepare solution B. The concentration of Zn(NO3)2·6H2O in solution B is 0.24-0.28 mol. The concentration of Al(NO3)3·9H2O was 0.1–0.12 mol / L; the corrosion inhibitor was dissolved in water to obtain solution C, and the concentration of the corrosion inhibitor in solution C was 10 mg / mL–50 mg / mL; then, solutions A, B and C were mixed and the pH was adjusted to 7–10; under a nitrogen atmosphere, the mixture was refluxed at a constant temperature for 12–24 h, and then precipitated at room temperature. After centrifugation, washing and vacuum freeze-drying were performed to obtain FG@LDH powder.

[0009] Step 3: Add the FG@LDH powder prepared in Step 2 to a mixture of n-butanol and xylene, then add epoxy resin, mix and ball mill, mix the ball milling product with polyamide curing agent evenly, coat it on the surface of the substrate to be treated, and obtain the coating after curing; wherein, the mass ratio of epoxy resin, xylene, n-butanol, FG@LDH and polyamide is (30~100):(4~20):(2~10):(0.05~0.3):(20~80).

[0010] Preferably, in step 1, the substrate to be treated is a metal substrate, using 80-mesh diamond abrasive with a sandblasting precision of Sa2.5 or higher. After sandblasting, the metal substrate is cleaned sequentially with water and ethanol, dried with cold air, and then immersed in an acetone solution.

[0011] Preferably, in step 2, the fluorine content in the fluorinated graphene is 20% to 60% by mass percentage, the average grain size of the fluorinated graphene is 0.5 to 5 μm, and the ultrasonic stirring time is 1 to 2 hours.

[0012] Preferably, in step 2, the corrosion inhibitor is one or both of sodium molybdate and disodium sebate.

[0013] Preferably, in step 2, the reaction temperature is 50–100°C under a nitrogen atmosphere, the precipitation is carried out at room temperature for 12–24 hours, and the product is then freeze-dried under vacuum for 12–24 hours.

[0014] Preferably, in step 3, the ball milling time is 0.5 to 5 hours, and the coating thickness after curing is 30 to 200 μm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The preparation method described in this invention uses a co-precipitation method to grow hydrotalcite using fluorinated graphene as a substrate, achieving a mass ratio of 1:6 to 1:7. This means that during the synthesis process, the amount of fluorinated graphene required is relatively small compared to the final hydrotalcite-modified fluorinated graphene. Since the preparation of fluorinated graphene is typically complex and costly, this mass ratio helps to significantly reduce the cost of the final product, making this high-performance material more competitive in the market and more valuable for practical applications.

[0017] 2. This invention improves the poor interfacial compatibility between fluorinated graphene and epoxy resin by introducing hydrotalcite onto the surface of fluorinated graphene, reducing interfacial defects between the two. Furthermore, the preparation method does not introduce any harmful substances, ensuring the environmental friendliness of the entire preparation process.

[0018] 3. This invention also reveals that hydrotalcite possesses a unique interlayer anion exchange capacity, allowing corrosion inhibitors to insert into its interlayer spaces. This enhances its exchange effect against corrosive media such as chloride ions, preventing these media from penetrating the coating and reaching the metal surface, thus protecting the metal from internal corrosion. Furthermore, the ions released during exchange can form a dense passivation film on the metal surface. This film effectively blocks the contact of moisture and oxygen, reducing corrosion reactions and further protecting the metal. This not only increases the material's versatility but also provides an additional mechanism for corrosion prevention.

[0019] 4. In the coating prepared by the method described in this invention, the combination of the large-sheet structure of fluorinated graphene and the unique properties of hydrotalcite effectively improves the long-term corrosion resistance of the coating. The large-sheet structure of fluorinated graphene provides a physical barrier, slowing down the penetration of corrosive media; while hydrotalcite provides chemical protection through its interlayer anion exchange properties. The synergistic effect of these two mechanisms ensures that the coating can maintain its protective function for a long time, even in harsh environments. Attached Figure Description

[0020] Figure 1 The images show scanning electron microscope (SEM) images of the surfaces of the modified fluorinated graphene prepared in Example 1 and the unmodified fluorinated graphene used in Comparative Example 1; where a represents Example 1 and b represents Comparative Example 1.

[0021] Figure 2 The graphs show the low-frequency impedance values ​​of the fluorinated graphene coatings prepared in Example 1 and Comparative Example 1, respectively.

[0022] Figure 3 The figures show the results of the neutral salt spray test on the fluorinated graphene coatings prepared in Example 1 and Comparative Example 1, respectively. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the present invention are within the scope of protection of the present invention.

[0024] Unless otherwise specified in the specific circumstances, the numerical ranges listed herein include upper and lower limits, as well as all integers and fractions within that range, but are not limited to the specific values ​​listed when the range is defined.

[0025] I. A method for preparing a corrosion-resistant self-healing coating of hydrotalcite-modified fluorinated graphene.

[0026] Step 1: Clean the surface of the substrate to be treated;

[0027] Step 2: Fluorinated graphene is added to an ethylene glycol aqueous solution and ultrasonically stirred to disperse it, obtaining solution A. The concentration of fluorinated graphene in solution A is 0.4 mg / mL to 2.0 mg / mL, and the volume ratio of ethylene glycol to water is (1-3):(1-3). Zn(NO3)2·6H2O and Al(NO3)3·9H2O are dissolved in water to prepare solution B. The concentration of Zn(NO3)2·6H2O in solution B is 0.24-0.28 mol / L, and the concentration of Al(NO3)3·9H2O is 0.24-0.28 mol / L. The concentration of 3·9H2O was 0.1–0.12 mol / L; the corrosion inhibitor was dissolved in water to obtain solution C, and the concentration of the corrosion inhibitor in solution C was 10 mg / mL–50 mg / mL; then, solutions A, B and C were mixed in a volume ratio of (4–6):(1–3):(1–3), and the pH was adjusted to 7–10; under a nitrogen atmosphere, the mixture was refluxed at a constant temperature for 12–24 h, and then precipitated at room temperature. After centrifugation, washing and vacuum freeze-drying were performed to obtain FG@LDH powder.

[0028] Step 3: Add the FG@LDH powder prepared in Step 2 to a mixture of n-butanol and xylene, then add epoxy resin, mix and ball mill, mix the ball milling product with polyamide curing agent evenly, coat it on the surface of the substrate to be treated, and obtain the coating after curing; wherein, the mass ratio of epoxy resin, xylene, n-butanol, FG@LDH and polyamide is (30~100):(4~20):(2~10):(0.05~0.3):(20~80).

[0029] This invention addresses the technical problems of existing technologies. The cost of fluorinated graphene limits its widespread use, and even the highest quality coatings can be damaged during actual service due to impacts, scratches, etc. Once the coating is damaged, moisture and oxygen can penetrate to the metal surface, leading to accelerated localized corrosion and ultimately affecting the corrosion resistance and service life of the entire structure. Therefore, this invention aims to achieve superior corrosion resistance in the prepared coating using as little fluorinated graphene as possible. To this end, this invention modifies fluorinated graphene by introducing hydrotalcite (TLC) onto its surface, solving the problem of poor interfacial compatibility between fluorinated graphene and epoxy resin. Furthermore, this invention discovers that inserting a corrosion inhibitor into the interlayer structure of the hydrotalcite enhances its exchange capacity with corrosive media such as chloride ions. The released ions can form a dense passivation film on the metal surface, further protecting the metal and preventing corrosive media from penetrating the coating through these interlayer structures and causing corrosion to the metal substrate. This invention also unexpectedly discovered that the prepared hydrotalcite-modified fluorinated graphene FG@LDH achieves excellent corrosion resistance with only a small amount, which greatly reduces the production cost. Furthermore, this invention found that the coating formed by adding FG@LDH to epoxy resin possesses a certain self-healing function. Because corrosion inhibitors are inserted between the hydrotalcite layers, even if damage inevitably occurs on the coating surface, the corrosion inhibitors between the hydrotalcite layers are slowly released. The released ions can then form a dense passivation film on the metal substrate surface. This passivation film can, to a certain extent, self-repair the damaged coating, thus extending its service life.

[0030] In some embodiments of this application, in step 1, the substrate to be treated is a metal substrate, which is blasted with 80-mesh diamond abrasive with a sandblasting precision of Sa2.5 or higher. After sandblasting, the metal substrate is cleaned with water and ethanol in sequence, dried with cold air, and then immersed in acetone solution to prevent oxidation from occurring on the surface of the metal substrate.

[0031] In some embodiments of this application, in step 2, the degree of fluorination of the fluorinated graphene in solution A must reach a certain level in order for the coating to have strong hydrophobicity and high stability; if the degree of fluorination is insufficient, the hydrophobicity and stability cannot meet the requirements; however, if the degree of fluorination is too high, it will increase the production cost. Therefore, based on mass percentage, the fluorine content in fluorinated graphene can be 20%, 30%, 40%, 50%, 60%, etc., as well as all ranges and sub-ranges between these values. The concentration of fluorinated graphene in solution A is controlled between 0.4 mg / mL and 2.0 mg / mL. Too low a concentration will not achieve the desired corrosion resistance, while too high a concentration will not only increase production costs but also cause agglomeration. Therefore, the concentration of fluorinated graphene in solution A can be 0.4 mg / mL, 0.8 mg / mL, 1.0 mg / mL, 1.5 mg / mL, 2.0 mg / mL, etc., as well as all ranges and sub-ranges between these values. At the same time, the size of the fluorinated graphene also needs to be controlled. If the size is too small, the advantages of the sheet structure of fluorinated graphene will be difficult to highlight, while if the size is too large, it will affect the arrangement of fluorinated graphene inside the coating, ultimately affecting the corrosion resistance of the coating. Therefore, the average grain size of fluorinated graphene can be 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, etc., as well as all ranges and sub-ranges between these values; the ultrasonic stirring time can be 1 h, 1.5 h, 2 h, etc., as well as all ranges and sub-ranges between these values. It should be understood that, in the embodiments, any of the above ranges can be combined with any other range.

[0032] In some embodiments of this application, in step 2, if the concentrations of solutions A, B, and C are too high, the final powder structure will not be formed properly; if the concentrations are too low, the final coating will have poor corrosion resistance. Therefore, the concentration of Zn(NO3)2·6H2O in solution B can be 0.24 mol / L, 0.25 mol / L, 0.26 mol / L, 0.27 mol / L, 0.28 mol / L, etc., and all ranges and sub-ranges between these values; the concentration of Al(NO3)3·9H2O can be 0.10 mol / L, 0.11 mol / L, 0.12 mol / L, etc., and all ranges and sub-ranges between these values; the concentration of the corrosion inhibitor in solution C can be 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, etc., and all ranges and sub-ranges between these values. It should be understood that, in the embodiments, any of the above ranges can be combined with any other range.

[0033] In some embodiments of this application, in step 2, the corrosion inhibitor is one or both of sodium molybdate and disodium sebate. The selected corrosion inhibitors are all environmentally friendly, do not cause environmental pollution, and have excellent corrosion inhibition effects. Sodium molybdate can effectively prevent metal corrosion in both aerobic and anaerobic environments, but other corrosion inhibitors do not have this effect; disodium sebate can also reduce the coefficient of friction and form a lubricant film on the surface of the friction pair, resulting in better friction performance of the prepared coating, an effect also not found in other corrosion inhibitors.

[0034] In some embodiments of this application, in step 2, the reaction temperature under a nitrogen atmosphere can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc., and all ranges and sub-ranges between the above values; the room temperature precipitation time can be 12h, 16h, 20h, 24h, etc., and all ranges and sub-ranges between the above values; the vacuum freeze-drying time can be 12h, 16h, 20h, 24h, etc., and all ranges and sub-ranges between the above values; it should be understood that, in the embodiments, any of the above ranges can be combined with any other range.

[0035] In some embodiments of this application, in step 3, the ball milling time can be 0.5h, 1h, 2h, 3h, 4h, 5h, etc., as well as all ranges and sub-ranges between the above values; it should be understood that, in the embodiments, any of the above ranges can be combined with any other range.

[0036] II. Examples and Comparative Examples

[0037] Example 1

[0038] (1) Pretreatment of workpiece: The carbon steel workpiece is sandblasted.

[0039] (2) Preparation of hydrotalcite-modified fluorinated graphene: 50 mL of deionized water (with CO2 removed) and 50 mL of ethylene glycol were weighed into a three-necked flask, and 0.1 g of fluorinated graphene was added and dispersed by ultrasonic stirring for 1 h to obtain solution A. Separately, 2.082 g of Zn(NO3)2·6H2O and 1.125 g of Al(NO3)3·9H2O were dissolved in 25 mL of deionized water (with CO2 removed) to obtain solution B. 0.5 g of sodium molybdate was dissolved in 25 mL of deionized water (with CO2 removed) to obtain solution C. Solutions A, B, and C were mixed and the pH was adjusted to 8.5. The mixture was refluxed at 80 °C for 12 h under a N2 atmosphere, followed by precipitation for 12 h. Finally, the mixture was centrifuged, washed, and freeze-dried under vacuum for 24 h to obtain 0.6–0.7 g of FG@LDH(M).

[0040] (3) Coating Preparation: The obtained FG@LDH(M) was added to a diluent containing n-butanol and xylene, wherein xylene and n-butanol were mixed in a mass ratio of 2:1. Then, epoxy resin E-44 was added and stirred thoroughly to form a mixture. The mixture was then ball-milled using a grinding mill. The resulting product was then mixed evenly with polyamide 650 curing agent, stirred for 10 minutes, and vacuumed to obtain FG@LDH(M) modified epoxy resin. The mass ratio of epoxy resin, FG@LDH(M), diluent, and polyamide 650 curing agent was 10:0.3:8:8. Finally, the obtained FG@LDH(M) modified epoxy resin was coated onto the surface of sandblasted Q235 carbon steel, with the film thickness controlled at 110±10μm.

[0041] Comparative Example 1

[0042] An improvement upon Example 1 was made, except that unmodified fluorinated graphene was used to replace FG@LDH in an equal amount. All other steps were identical to Example 1, resulting in an unmodified fluorinated graphene coating.

[0043] Example 2

[0044] (1) Pretreatment of workpiece: The carbon steel workpiece is sandblasted.

[0045] (2) Preparation of hydrotalcite-modified fluorinated graphene: 50 mL of CO2-free deionized water and 50 mL of ethylene glycol were weighed into a three-necked flask, and 0.1 g of fluorinated graphene was added and dispersed by ultrasonic stirring for 1 h to obtain solution A. Separately, 2.082 g of Zn(NO3)2·6H2O and 1.125 g of Al(NO3)3·9H2O were dissolved in 25 mL of CO2-free deionized water to obtain solution B. 0.5 g of disodium sebate was dissolved in 25 mL of CO2-free deionized water to obtain solution C. Solutions A, B, and C were mixed and the pH was adjusted to 9. The mixture was refluxed at 50 °C for 12 h under a N2 atmosphere, followed by precipitation for 12 h. Finally, the mixture was centrifuged, washed, and freeze-dried under vacuum for 24 h to obtain 0.6–0.7 g of FG@LDH(SB).

[0046] (3) Coating preparation: The obtained FG@LDH(SB) was added to a diluent containing n-butanol and xylene, wherein xylene and n-butanol were mixed in a mass ratio of 2:1. Then epoxy resin E-44 was added and stirred thoroughly to form a mixture. The mixture was then ball-milled using a grinding mill. The resulting product was then mixed evenly with polyamide 651 curing agent, stirred for 10 min, and vacuumed to obtain FG@LDH(SB) modified epoxy resin. The mass ratio of epoxy resin, FG@LDH(SB), diluent, and polyamide 651 curing agent was 10:0.3:8:4. Finally, the obtained FG@LDH(SB) modified epoxy resin was coated onto the surface of sandblasted Q235 carbon steel, with the film thickness controlled at 110±10μm. The coating was then cured at 25~30℃ for 72h to obtain the FG@LDH(SB) coating.

[0047] Example 3

[0048] (1) Pretreatment of workpiece: The carbon steel workpiece is sandblasted.

[0049] (2) Preparation of hydrotalcite-modified fluorinated graphene: 50 mL of CO2-free deionized water and 50 mL of ethylene glycol were weighed into a three-necked flask, and 0.1 g of fluorinated graphene was added and dispersed by ultrasonic stirring for 1 h to obtain solution A. Separately, 2.082 g of Zn(NO3)2·6H2O and 1.125 g of Al(NO3)3·9H2O were dissolved in 25 mL of CO2-free deionized water to obtain solution B. 0.25 g of disodium sebate and 0.25 g of sodium molybdate were dissolved in 25 mL of CO2-free deionized water to obtain solution C. Solutions A, B, and C were mixed and the pH was adjusted to 8.5. The mixture was refluxed at 50 °C for 12 h under a N2 atmosphere, followed by precipitation for 12 h. Finally, the mixture was centrifuged, washed, and freeze-dried under vacuum for 24 h to obtain 0.6–0.7 g of FG@LDH (MS).

[0050] (3) Coating preparation: The prepared FG@LDH(MS) was added to a diluent containing n-butanol and xylene, wherein xylene and n-butanol were mixed in a mass ratio of 2:1. Then epoxy resin E-44 was added and stirred thoroughly to form a mixture. The mixture was then ball-milled using a grinding mill. The resulting product was then mixed evenly with polyamide 650 curing agent, stirred for 10 min, and vacuumed to obtain FG@LDH(MS) modified epoxy resin. The mass ratio of epoxy resin, FG@LDH(MS), diluent, and polyamide 650 curing agent was 10:0.3:8:6. Finally, the prepared FG@LDH(MS) modified epoxy resin was coated onto the surface of sandblasted Q235 carbon steel, with the film thickness controlled at 110±10 μm. The coating was then cured at 25-30℃ for 72 h to obtain the FG@LDH(MS) coating.

[0051] III. Performance Analysis

[0052] 1. Microscopic morphology testing

[0053] Taking Example 1 and Comparative Example 1 as examples, the microstructure of FG@LDH(M) and unmodified fluorinated graphene prepared in Example 1 were observed as follows: Figure 1 As shown, Example 1 ( Figure 1 a) The hydrotalcite in this example exhibits primarily longitudinal growth on the surface of fluorinated graphene, with a size of approximately 50–200 nm; Comparative Example 1 ( Figure 1 b) The fluorinated graphene exhibits a distinct layered structure with a size of approximately 1000 nm. This indicates that the preparation method described in this application can successfully introduce hydrotalcite onto the surface of the fluorinated graphene.

[0054] 2. Electrochemical Impedance Spectroscopy Experiment

[0055] The coatings obtained in Examples 1-3 and Comparative Example 1 were subjected to electrochemical impedance spectroscopy in a 3.5 wt% NaCl solution. The low-frequency impedance modulus curves are shown below. Figure 2 After 1200 hours of testing, the coating of Example 1 showed a trend of first decreasing, then increasing, and finally stabilizing. This is closely related to the anion exchange between the hydrotalcite layers. The release of the corrosion inhibitor effectively further protected the carbon steel, and the long-term low-frequency impedance modulus remained consistently at 10. 10 Ω·cm 2 Compared to the coating in Comparative Example 1, the corrosion resistance of the modified epoxy coating FG@LDH(M) was improved by 2 to 3 orders of magnitude, indicating that the FG@LDH(M) coating prepared with the same amount of FG and FG@LDH(M) exhibits better corrosion resistance. Furthermore, 0.1g of FG can produce 0.6g to 0.7g of FG@LDH(M), which significantly reduces the application cost of FG in anti-corrosion coatings. The same applies to Examples 2 and 3; the low-frequency impedance modulus of the FG@LDH coatings prepared in Examples 2 and 3 consistently remained above 10. 10 Ω·cm 2 .

[0056] 3. Neutral salt spray test

[0057] Carbon steel with modified coatings prepared in Examples 1-3 and Comparative Example 1 were placed in a neutral salt spray test chamber and tested using 5% sodium chloride at a temperature of 35°C. The coatings were removed and photographed periodically. The results of the neutral salt spray test are as follows: Figure 3 As shown, Example 1 ( Figure 3 The salt spray resistance of the coating prepared in Example 1 exceeded 800 hours, and due to the interlayer anion exchange properties of the hydrotalcite, the scratches showed significant shrinkage, indicating that the coating prepared in Example 1 was undergoing self-repair. (Comparative Example 1) Figure 3The salt spray resistance of the first example is less than 72 h. The salt spray resistance of Examples 2 and 3 reaches more than 700 h and more than 900 h, respectively. The above results show that the hydrotalcite modified with sodium molybdate or disodium sebacic acid corrosion inhibitor significantly improves the salt spray resistance of the coating and can better meet the application requirements of marine environment; in addition, Examples 2 and 3 also show a certain self-healing ability.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a corrosion-resistant self-healing coating of hydrotalcite-modified fluorinated graphene, characterized in that, The following steps describe the growth of hydrotalcite using fluorinated graphene as a substrate, where the hydrotalcite allows corrosion inhibitors to be inserted into its interlayer spaces: Step 1: Clean the surface of the substrate to be treated; Step 2: Fluorinated graphene is added to an ethylene glycol aqueous solution and ultrasonically stirred to disperse it, obtaining solution A. The concentration of fluorinated graphene in solution A is 0.4 mg / mL to 2.0 mg / mL, and the volume ratio of ethylene glycol to water is (1~3):(1~3). Zn(NO3)2·6H2O and Al(NO3)3·9H2O are dissolved in water to prepare solution B. The concentration of Zn(NO3)2·6H2O in solution B is 0.24~0.28 mol / L, and the concentration of Al(NO3)3·9H2O is 0.1~0.12 mol / L. mol / L; Dissolve the corrosion inhibitor in water to obtain solution C, the concentration of the corrosion inhibitor in solution C is 10mg / mL~50mg / mL; Subsequently, mix solution A, solution B and solution C in a volume ratio of (4~6):(1~3):(1~3) and adjust the pH value to 8.5~9; Under a nitrogen atmosphere, reflux at a constant temperature for 12~24h, then precipitate at room temperature, centrifuge, wash and freeze dry under vacuum to obtain FG@LDH powder; Step 3: Add the FG@LDH powder prepared in Step 2 to a mixture of n-butanol and xylene, then add epoxy resin, mix and ball mill, mix the ball milling product with polyamide curing agent, coat it on the surface of the substrate to be treated, and obtain the coating after curing; wherein, the mass ratio of epoxy resin, xylene, n-butanol, FG@LDH and polyamide is (30~100):(4~20):(2~10):(0.05~0.3):(20~80); The corrosion inhibitor is one or both of sodium molybdate and disodium sebate; when the corrosion inhibitor is a mixture of sodium molybdate and disodium sebate, the mass ratio of sodium molybdate to disodium sebate is 1:

1. Fluorinated graphene contains 20% to 60% fluorine by mass percentage.

2. The preparation method according to claim 1, characterized in that, In step 1, the substrate to be treated is a metal substrate, which is blasted with 80-mesh diamond abrasive with a sandblasting precision of Sa2.5 or higher. After sandblasting, the metal substrate is cleaned with water and ethanol in sequence, dried with cold air, and then immersed in acetone solution.

3. The preparation method according to claim 1, characterized in that, In step 2, the average grain size of the fluorinated graphene is 0.5~5μm, and the ultrasonic stirring time is 1~2h.

4. The preparation method according to claim 1, characterized in that, In step 2, the reaction temperature is 50~100℃ under a nitrogen atmosphere, precipitation is carried out at room temperature for 12~24h, and freeze-drying is carried out under vacuum for 12~24h.

5. The preparation method according to claim 1, characterized in that, In step 3, the ball milling time is 0.5~5h, and the coating thickness after curing is 30~200μm.

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