Preparation method of layered double-metal hydroxide anticorrosive coating

Abstract

The invention discloses a preparation method of a layered double hydroxide anticorrosive coating, which comprises the following steps: firstly, preparing nickel-aluminum layered double hydroxides (M1M2-LDHs) on the surface of a metal substrate; afterwards, corrosion inhibition anions and nitrate ions in the M1M2-LDHs are exchanged through an impregnation method, and the process is based on the ion exchange principle and aims at introducing ion components with the corrosion inhibition function to enhance the protection capacity of the coating. And then, dipping the obtained product in a corresponding solution containing a surface modifier, and carrying out sufficient reaction for a certain period of time under a constant temperature condition, so as to obtain the final layered double-metal hydroxide anti-corrosion coating. The coating has self-cleaning performance and can effectively reduce adhesion of external pollutants on the surface of the coating. From the aspect of corrosion protection performance, the electrochemical corrosion current of the metal substrate can be obviously reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of coating materials, and more specifically to a method for preparing an anti-corrosion coating of a layered double hydroxide. Background Art

[0002] With the development of modernization, metals are widely used in many fields such as construction, transportation, industrial manufacturing, and electronic appliances. However, the accompanying metal corrosion phenomenon has seriously reduced the service life of metals and caused huge economic losses. Therefore, a variety of anti-corrosion methods have emerged, such as electrochemical deposition, coating, and anodic protection. However, traditional methods face some challenges in practical applications, including poor durability, environmental pollution, toxicity, and high costs. Therefore, exploring new, environmentally friendly, efficient, and long-lasting anti-corrosion technologies has become a hot topic in materials science research.

[0003] In recent years, superhydrophobic surfaces have attracted extensive attention in the field of corrosion protection due to their excellent hydrophobicity, antifouling and self-cleaning properties. Such surfaces effectively reduce the contact between liquid water and the substrate, thereby reducing the penetration of corrosive agents. In addition, the self-cleaning property can carry away contaminants through rolling droplets, thereby keeping the surface clean.

[0004] Due to the unique layered structure and tunable properties of layered double hydroxides (LDHs), research on further improving their corrosion resistance has attracted increasing attention. LDHs are composed of positively charged metal hydroxide layers and inserted anions, and their structure can be expressed as Among them, M 2+ 、M 3+ represents the metal cation in LDHs, A n- Represents interlayer anions and can be replaced by other anions. This structure gives LDHs excellent anion exchange capacity and sustained release properties. In addition, the unique structure of the class enables them to release ions to exchange with corrosive ions in the early stages of the corrosion process, thereby extending their durability [Iqbal MA, Sun LY, Barrett A.T., et al. Layered double hydroxide protective films developed on aluminum and aluminum alloys: synthetic methods and anti-corrosion mechanisms. Coatings, 2020, 10: 428.].

[0005] There are two common methods to improve the corrosion resistance of LDHs materials. The first method is to grow an LDHs coating in situ directly on the surface of the substrate and then treat the LDHs; the second method is to combine LDHs powder with an organic coating to enhance the overall corrosion resistance of the material. In terms of metal corrosion resistance, the method of growing LDHs in situ on the metal surface is more effective than the powder mixing method. This is because in situ growth allows for stronger adhesion to the metal surface, making it more suitable for corrosion resistance. For example, Chinese patent CN117684180A discloses that magnesium-iron layered double hydroxides grown in situ on the surface of steel improve the corrosion resistance of steel plates. In addition, there are two other methods that can additionally improve the corrosion resistance of in situ grown LDHs coatings: first, treating the coating with low surface energy; second, adding corrosion-inhibiting ions to LDHs. For example, Cao et al. prepared LDHs on 5052 aluminum alloy by in-situ growth method, and then immersed it in stearic acid to obtain STA-LDH coating; the corrosion current density was reduced by about two orders of magnitude [Cao HJ Low adhesive and superhydrophobic LDH coating for anti-corrosion and self-cleaning. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2022, 652, 129893.]. Wang et al. exchanged the original nitrate ions in the intermediate layer with 8-hydroxyquinoline anions, and the coating could maintain its corrosion resistance even if it was destroyed [Wang LD, Zong QF, Sun W., et al. Chemical modification of hydrotalcite coating for enhanced corrosion resistance. Corrosion Science, 2015, 93: 256-266.]. It can be seen that the research on the long-term corrosion resistance of LDHs coating is still insufficient. At present, the research on the long-term corrosion resistance of LDHs coating is still an area to be explored. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing an anti-corrosion coating of a layered double hydroxide. The present invention obtains a layered double hydroxide with corrosion inhibition by inserting corrosion-inhibiting ions into the layered structure of the layered double hydroxide; and on this basis, combined with surface modification technology, the prepared layered double hydroxide is endowed with super-hydrophobicity and corrosion inhibition ability; the layered double hydroxide prepared by the method can have super-hydrophobicity and corrosion inhibition ability, and has good self-cleaning ability, which can effectively prevent pollutants from accumulating on the coating surface, thereby achieving a long-term anti-corrosion effect.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0009] 1) dissolving a soluble first metal salt and a soluble second metal salt in deionized water to obtain a mixed salt solution; dissolving an alkali salt in deionized water to obtain an alkali solution; adjusting the pH value of the mixed salt solution with the alkali solution, and then placing the mixed salt solution and the metal substrate in a reaction kettle;

[0010] 2) The reactor is heated to perform a hydrothermal reaction to prepare M on the surface of the metal plate. 1 M 2 -LDHs, thus obtaining an apparent M 1 M 2 -Metal plates for LDHs;

[0011] 3) dissolving the corrosion inhibitor in deionized water to prepare a corrosion inhibitor solution, and 1 M 2 -LDHs metal plate is placed in a corrosion inhibitor solution to undergo ion exchange reaction to obtain a layered double metal hydroxide with corrosion inhibition function;

[0012] 4) dissolving the surface modifier in a solvent to obtain a surfactant solution, and immersing the layered double hydroxide obtained in step 3) in the surfactant solution to obtain a super hydrophobic layered double hydroxide coating M-LDHs-X with corrosion inhibition function.

[0013] Preferably, in step 1, the first metal salt is a soluble nickel salt, and the second metal salt is a soluble aluminum salt.

[0014] Preferably, the soluble nickel salt is selected from one or more of the following substances: nickel nitrite, nickel acetate tetrahydrate, nickel iodide, nickel chloride hexahydrate, nickel bromide, nickel sulfate heptahydrate, and nickel nitrate hexahydrate; the soluble aluminum salt is selected from one or more of the following substances: aluminum iodide, aluminum phosphate, aluminum citrate, aluminum acetate, aluminum chloride hexahydrate, aluminum nitrate nonahydrate, and aluminum sulfate hexahydrate.

[0015] Preferably, in step 1), in the mixed salt solution, the concentration of soluble nickel salt is 0.01-1 mol / L, and the molar ratio of the soluble nickel salt to the soluble aluminum salt is 1:1-4:1; the hydroxide concentration in the alkaline solution is 0.1-4 mol / L; and the pH value of the mixed salt solution is adjusted to 5-10.

[0016] Preferably, in step 1), the alkali salt is selected from one or more of the following substances: urea, potassium hydroxide, sodium hydroxide, and ammonia water.

[0017] Preferably, in step 1), the metal substrate is selected from one of the following: magnesium plate, iron plate, zinc plate, copper plate, and aluminum plate.

[0018] Preferably, in step 2), the temperature of the hydrothermal reaction is 50-140°C; more preferably, the temperature of the hydrothermal reaction is 70-120°C.

[0019] Preferably, in step 2), the hydrothermal reaction time is 6-16 h; more preferably, the hydrothermal reaction time is 8-16 h.

[0020] Preferably, in step 3), the corrosion inhibitor is selected from one or more of the following substances: sodium phosphate, potassium phosphate, sodium hexametaphosphate, 8-hydroxyquinoline, 2-mercaptobenzothiazole, sodium nitrite, sodium molybdate, ammonium molybdate, sodium orthovanadate, and sodium metavanadate; more preferably, the corrosion inhibitor is selected from one or more of the following substances: sodium phosphate, sodium hexametaphosphate, 8-hydroxyquinoline, 2-mercaptobenzothiazole, sodium nitrite, sodium molybdate, sodium orthovanadate, and sodium metavanadate.

[0021] Preferably, in step 3), the concentration of the corrosion inhibitor solution is 0.01-0.6 mol / L, more preferably, the concentration of the corrosion inhibitor solution is 0.05-0.5 mol / L.

[0022] Preferably, in step 3), the temperature of the ion exchange reaction is 30-90°C, more preferably, the temperature of the ion exchange reaction is 40-80°C.

[0023] In step 3), the ion exchange reaction time is 1-16 hours; more preferably, the ion exchange reaction time is 4-14 hours.

[0024] Preferably, in step 4), the surface modifier is selected from one or more of the following substances: tridecafluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, sodium laurate, myristic acid, oleic acid, stearic acid, sodium stearate, 1-aminooctadecane, dodecylammonium chloride; more preferably, the surface modifier is selected from one or more of the following substances: 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, sodium laurate, myristic acid, oleic acid, stearic acid, 1-aminooctadecane, dodecylammonium chloride.

[0025] Preferably, in step 4), the concentration of the surface modifier is 0.01-1.0 mol / L; more preferably, the concentration of the surface modifier is 0.05-0.6 mol / L.

[0026] Preferably, in step 4), the immersion temperature is 30-90°C; more preferably, the immersion temperature is 40-80°C.

[0027] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0028] Unless otherwise specified, all raw materials in the present invention can be purchased from the market, and the equipment used in the present invention can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0029] Compared with the prior art, the present invention has the following beneficial effects: :

[0030] 1) The anti-corrosion coating prepared by the present invention can flexibly adjust the interlayer structure, surface energy and chemical composition of the layered double metal hydroxide by adjusting the concentration of the corrosion inhibitor and the content of the surface modifier to adjust the anti-corrosion effect;

[0031] 2) The present invention has multiple anti-corrosion barriers, combined with super-hydrophobicity, ion exchange and physical barrier properties, which can prevent the invasion of corrosive media from all aspects and maintain a long-term anti-corrosion effect;

[0032] 3) Good self-cleaning performance, which can prevent pollutants from accumulating on the coating surface to increase the service life of the coating;

[0033] 4) The present invention adopts conventional chemical reagents and a simple hydrothermal process for preparation, is easy to operate, avoids expensive equipment and complicated processing. Compared with the traditional anti-corrosion method, the preparation process is pollution-free and the material stability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Figure 1 Schematic diagram of the self-cleaning of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0036] Figure 2 This is a contact angle test diagram of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0037] Figure 3 This is a surface roughness spectrum of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0038] Figure 4 The X-ray diffraction pattern of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0039] Figure 5This is a scanning electron microscope image of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0040] Figure 6 The Tafel spectrum and attached table of the layered double metal hydroxide anticorrosive coating prepared in Example 1;

[0041] Figure 7 This is a scanning electron microscope image of the layered double metal hydroxide anti-corrosion coating prepared in Comparative Example 3;

[0042] Figure 8 This is the Nyquist spectrum of the layered double metal hydroxide anti-corrosion coating prepared in Comparative Example 4. DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0044] As one aspect of the present invention, a method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0045] 1) dissolving a soluble first metal salt and a soluble second metal salt in deionized water to obtain a mixed salt solution; dissolving an alkali salt in deionized water to obtain an alkali solution; adjusting the pH value of the mixed salt solution with the alkali solution, and then placing the mixed salt solution and the metal substrate in a reaction kettle;

[0046] 2) The reactor is heated to perform a hydrothermal reaction to prepare M on the surface of the metal plate. 1 M 2 -LDHs, thus obtaining an apparent M 1 M 2 -Metal plates for LDHs;

[0047] 3) dissolving the corrosion inhibitor in deionized water to prepare a corrosion inhibitor solution, and 1 M 2 -LDHs metal plate is placed in a corrosion inhibitor solution to undergo ion exchange reaction to obtain a layered double metal hydroxide with corrosion inhibition function;

[0048] 4) dissolving the surface modifier in a solvent to obtain a surfactant solution, and immersing the layered double hydroxide obtained in step 3) in the surfactant solution to obtain a super hydrophobic layered double hydroxide coating M-LDHs-X with corrosion inhibition function.

[0049] According to some examples of the present invention, in step 1), the first metal salt is a soluble nickel salt, and the second metal salt is a soluble aluminum salt.

[0050] According to some examples of the present invention, in step 1), the soluble nickel salt is selected from one or more of the following substances: nickel iodide, nickel ammonium sulfate, nickel perchlorate, nickel nitrite, nickel acetate tetrahydrate, nickel chloride hexahydrate, nickel bromide, nickel sulfate heptahydrate, nickel nitrate hexahydrate; the soluble aluminum salt is selected from one or more of the following substances: aluminum phosphate, aluminum bromide, aluminum citrate, ammonium aluminum sulfate, aluminum iodide, aluminum acetate, aluminum chloride hexahydrate, aluminum nitrate nonahydrate, aluminum sulfate hexahydrate. Different anions in different metal salt solutions may result in different anions between the layers of the generated layered metal double hydroxide.

[0051] According to some examples of the present invention, in step 1), in the mixed salt solution, the concentration of soluble nickel salt is 0.01-1 mol / L, the molar ratio of the soluble nickel salt to the soluble aluminum salt is 1:1-4:1, or 1:1-3:1, or 1:1-2:1; the hydroxide concentration in the alkaline solution is 0.1-4 mol / L; the pH value of the mixed salt solution is adjusted to 5-10. Different metal salt concentrations have an impact on their nucleation and growth, product morphology, interlayer structure and performance. Low concentrations are conducive to the formation of products with uniform size, regular morphology and stable interlayer structure, while high concentrations are prone to uneven particles, irregular morphology, disordered interlayer structure, etc.; in terms of alkali solution concentration, low concentrations are conducive to the formation of products with uniform size, regular morphology and regular interlayer structure, while high concentrations are prone to uneven growth, irregular morphology, disordered interlayer structure, etc. If the pH of the mixed salt solution is too low, the precipitation reaction of producing LDHs will be incomplete, and if the pH is too high, some metal ions will react excessively with hydroxide ions to produce by-products.

[0052] According to some examples of the present invention, in step 1), the alkali salt is selected from one or more of the following substances: urea, potassium hydroxide, sodium hydroxide, and ammonia water. Different types of alkali solutions have significant differences in reaction rate, nucleation and growth process, particle morphology and size control, purity assurance, etc. when preparing hydroxide nanoparticles. Strong alkaline alkali solutions react quickly and easily cause agglomeration and may affect purity. Weak bases are conducive to regulating particle characteristics due to the reversible reaction but may be interfered by their own impurities. Alkali sources that slowly release hydroxide are conducive to precise control of nucleation and growth and can reduce the introduction of impurities to improve purity.

[0053] According to some examples of the present invention, in step 1), the metal substrate is selected from one of the following: magnesium plate, iron plate, zinc plate, copper plate, and aluminum plate. When layered double hydroxides are grown in situ on the surfaces of different metal plates, the surface characteristics of the metal plates will have a significant impact on the nucleation rate and growth mode during the growth process, the crystal orientation and interlayer structure of the product structure, and the mechanical properties, catalytic and adsorption properties of the material.

[0054] According to some examples of the present invention, in step 2), the temperature of the hydrothermal reaction is 50-140°C; more preferably, the temperature of the hydrothermal reaction is 70-120°C. The effect of reaction temperature on the in-situ growth reaction is reflected in key aspects such as rate, morphology and product stability: high temperature accelerates molecular motion, increases reaction rate and promotes diffusion, which is conducive to rapid nucleation or crystal growth, but may also lead to polycrystalline, defects or side reactions; low temperature inhibits the nucleation rate, which is conducive to directional growth and reduction of defects.

[0055] According to some examples of the present invention, in step 2), the hydrothermal reaction time is 6-16 hours; more preferably, the hydrothermal reaction time is 8-16 hours. The in-situ growth reaction time directly affects the reaction process and product characteristics. Insufficient time may lead to insufficient reaction, low crystal nucleation rate or incomplete growth; too long time may cause excessive growth, grain coarsening or side reactions, and even destroy the stability of the original structure. Time optimization requires balancing kinetic control and thermodynamic stability to obtain products with ideal size, morphology and performance.

[0056] According to some examples of the present invention, in step 3), the corrosion inhibitor is selected from one or more of the following substances: sodium phosphate, potassium phosphate, sodium hexametaphosphate, 8-hydroxyquinoline, 2-mercaptobenzothiazole, sodium nitrite, sodium molybdate, ammonium molybdate, sodium orthovanadate, sodium metavanadate; more preferably, the corrosion inhibitor is selected from one or more of the following substances: sodium phosphate, sodium hexametaphosphate, 8-hydroxyquinoline, 2-mercaptobenzothiazole, sodium nitrite, sodium molybdate, sodium orthovanadate, sodium metavanadate. Different corrosion inhibitors will cause different corrosion-inhibiting anions to intercalate LDHs, affecting the corrosion inhibition ability under different environments.

[0057] According to certain examples of the present invention, in step 3), the concentration of the corrosion inhibitor solution is 0.01-0.6 mol / L, and more preferably, the concentration of the corrosion inhibitor solution is 0.05-0.5 mol / L. When the concentration of the corrosion inhibitor solution is too low, the corrosion inhibition effect is poor, it is difficult to form an effective protective film on the surface of the sample, and it is impossible to fully inhibit the reaction between the corrosive medium and the sample, resulting in accelerated corrosion rate, deeper corrosion, and increased risk of local corrosion. If the concentration of the corrosion inhibitor solution is too high, it will change the physical properties and chemical stability, such as excessive deposition on the surface to change the roughness or react with the sample or other components.

[0058] According to some examples of the present invention, in step 3), the temperature of the ion exchange reaction is 30-90° C., more preferably, the temperature of the ion exchange reaction is 40-80° C. When the temperature is too high, the reaction rate of the corrosion inhibitor and the product may be accelerated, resulting in excessive consumption or decomposition of the corrosion inhibitor, and reducing the corrosion inhibition effect; at the same time, high temperature may induce side reactions, change the surface properties of the sample (such as oxidation, roughness change, etc.) or affect the performance of the sample.

[0059] According to certain examples of the present invention, in step 3), the time of the ion exchange reaction is 1-16 hours; more preferably, the time of the ion exchange reaction is 4-14 hours. If the reaction time between the product and the corrosion inhibitor is too long or too short, different effects will occur: when the reaction time is too short, the corrosion inhibitor may not be able to fully react with the surface of the product, and it is difficult to form a uniform and dense protective film, resulting in unsatisfactory corrosion inhibition effect and failure to effectively inhibit corrosion; when the reaction time is too long, the corrosion inhibitor may be excessively deposited on the surface of the product or unnecessary side reactions may occur, changing the surface properties of the product, and even affecting the performance of the product, and at the same time may increase the consumption of the corrosion inhibitor and the processing cost.

[0060] According to some examples of the present invention, in step 4), the surface modifier is selected from one or more of the following substances: tridecafluorooctyl triethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyl trimethoxysilane, sodium laurate, myristic acid, oleic acid, stearic acid, sodium stearate, 1-aminooctadecane, dodecyl ammonium chloride; more preferably, the surface modifier is selected from one or more of the following substances: 1H, 1H, 2H, 2H-perfluorodecyl trimethoxysilane, sodium laurate, myristic acid, oleic acid, stearic acid, 1-aminooctadecane, dodecyl ammonium chloride. The hydrophobicity and durability of products treated with different modifiers are different, which will affect the self-cleaning, waterproof, weather resistance and chemical stability of the product.

[0061] According to some examples of the present invention, in step 4), the concentration of the surface modifier is 0.01-1.0 mol / L; more preferably, the concentration of the surface modifier is: 0.05-0.6 mol / L. When the concentration of the surface modifier is too low, it is difficult to form a uniform and dense super hydrophobic layer on the surface of the product, resulting in insufficient hydrophobicity, poor self-cleaning and waterproof effects; when the concentration is too high, the modifier may accumulate excessively on the surface, forming an uneven coating, affecting the appearance and performance of the product.

[0062] According to some examples of the present invention, in step 4), the immersion temperature is 30-90° C.; more preferably, the immersion temperature is 40-80° C. When the temperature is too high, the decomposition or volatilization of the modifier may be accelerated, resulting in uneven modification effect and even damage to the surface structure of the sample; when the temperature is too low, the reaction rate slows down, and the modifier is difficult to fully react with the sample surface, and a uniform super-hydrophobic layer cannot be formed, which affects the hydrophobic performance.

[0063] Example 1

[0064] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0065] Take 2.91g of nickel nitrate hexahydrate and 1.82g of aluminum nitrate nonahydrate and dissolve them in 100mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 2:1. Take 4g of sodium hydroxide and dissolve it in 100mL of deionized water to prepare an alkaline solution with a hydroxide concentration of 1mol / L. Slowly add the alkaline solution to the mixed salt solution under magnetic stirring to adjust the pH of the mixed metal salt solution to 6.5. Place a clean zinc plate vertically in the reactor liner, add the above solution, react at 120°C for 16h, and then wash with deionized water and dry naturally to obtain N iAl-LDHs sample; then 0.61g of sodium orthovanadate was dissolved in 100mL of deionized water to prepare a corrosion inhibitor solution, the NiAl-LDHs sample was immersed in it, reacted at 60°C for 12h, washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample; finally, 2.84g of stearic acid was dissolved in 100mL of ethanol solution to obtain a surface modifier solution with a concentration of 0.1mol / L, the corrosion-inhibiting ion intercalation sample was immersed in it, reacted at 50°C for 1h, washed and naturally air-dried to obtain a sample with corrosion-inhibiting ion intercalation and super hydrophobicity.

[0066] Figure 1 Schematic diagram of the self-cleaning of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0067] Figure 2 This is a contact angle test diagram of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0068] Figure 3 This is a surface roughness spectrum of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0069] Figure 4 The X-ray diffraction pattern of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0070] Figure 5 This is a scanning electron microscope image of the layered double metal hydroxide anti-corrosion coating prepared in Example 1;

[0071] Figure 6 This is the Tafel spectrum and attached table of the layered double hydroxide anti-corrosion coating prepared in Example 1.

[0072] Example 2

[0073] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0074] Take 0.24g of nickel chloride hexahydrate and 0.24g of aluminum chloride nonahydrate, dissolve them in 100mL of deionized water to obtain a mixed salt solution, at which the molar ratio of nickel salt to aluminum salt is about 1:1. ; Dissolve 8g of sodium hydroxide in 100mL of deionized water to obtain an alkaline solution, the hydroxide concentration ratio of which is about 2mol / L. Under the action of magnetic stirring, slowly add the alkaline solution to the mixed salt solution and adjust the pH to 6.5; place a clean aluminum plate vertically in the inner tank of the reactor, and then add the above solution; react the reactor at 90℃ for 12h, wash the sample with deionized water after the reaction is completed and air dry it naturally to obtain a NiAl-LDHs sample.

[0075] 2.05 g of sodium molybdate was dissolved in 100 mL of deionized water to prepare a corrosion inhibitor solution. The NiAl-LDHs sample was immersed in the corrosion inhibitor solution and reacted at 40°C for 8 h. After completion, it was washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalated sample.

[0076] 1.42 g of stearic acid was dissolved in 100 mL of ethanol solution to obtain a surface modifier solution with a concentration of 0.05 mol / L. The sample with corrosion inhibition ion intercalation was immersed in the modifier solution and reacted at 60°C for 4 h. The obtained sample was washed and naturally air-dried to finally obtain a sample with corrosion inhibition ion intercalation and super hydrophobicity.

[0077] Example 3

[0078] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0079] 2.81 g of nickel sulfate heptahydrate and 1.71 g of aluminum sulfate hexadecahydrate were dissolved in 100 mL of deionized water to obtain a mixed salt solution, at which the molar ratio of nickel salt to aluminum salt was about 2:1; 12 g of urea was dissolved in 200 mL of deionized water to prepare an alkaline solution, the hydroxide concentration of which was about 1 mol / L. Under magnetic stirring, the alkaline solution was slowly added to the mixed salt solution to adjust the pH of the mixed metal salt solution to 7; a clean iron plate was vertically placed in the inner tank of a reactor, and the above-obtained solution was added, and the reactor was placed at 100°C for reaction for 10 hours. After the reaction, the sample was washed with deionized water and naturally air-dried to obtain a NiAl-LDHs sample.

[0080] 3.06 g of sodium hexametaphosphate was dissolved in 100 mL of deionized water to prepare a corrosion inhibitor solution. The NiAl-LDHs sample was immersed in the corrosion inhibitor solution and reacted at 60° C. for 6 h. After completion, it was washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalated sample.

[0081] 1.33 g of sodium laurate was dissolved in 100 mL of ethanol solution to obtain a surface modifier solution with a concentration of 0.06 mol / L. The sample with corrosion inhibition ion intercalation was immersed in it and reacted at 50°C for 4 hours. The obtained sample was washed and naturally air-dried to finally obtain a sample with corrosion inhibition ion intercalation and super hydrophobicity.

[0082] Example 4

[0083] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0084] 8.39 g of nickel chloride hexahydrate and 2.41 g of aluminum chloride nonahydrate were dissolved in 100 mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 3:1. 11.2 g of potassium hydroxide was dissolved in 200 mL of deionized water to prepare an alkaline solution with a hydroxide concentration of 1 mol / L. The alkaline solution was slowly added to the mixed salt solution under magnetic stirring to adjust the pH of the mixed metal salt solution to 8. A clean zinc plate was placed vertically in the reactor liner, the above solution was added, and the reaction was carried out at 70 ° C for 14 h. After the reaction, the mixture was washed with deionized water and naturally air-dried to obtain a NiAl-LDHs sample.

[0085] 1.38 g of sodium nitrite was dissolved in 100 mL of deionized water to prepare a corrosion inhibitor solution, and the NiAl-LDHs sample was immersed in the solution, reacted at 40° C. for 4 h, and washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample;

[0086] Finally, 10 mL of tridecafluorooctyl triethoxysilane was mixed with 100 mL of deionized water to obtain a surface modifier solution, and the corrosion-inhibiting ion intercalation sample was immersed therein, reacted at 70° C. for 2 h, and washed and naturally air-dried to obtain a sample with corrosion-inhibiting ion intercalation and super-hydrophobicity.

[0087] Example 5

[0088] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0089] 1.45 g of nickel nitrate hexahydrate and 0.63 g of aluminum nitrate nonahydrate were dissolved in 100 mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 3:1. 5.61 g of potassium hydroxide was dissolved in 200 mL of deionized water to prepare an alkaline solution with a hydroxide concentration of 0.5 mol / L. The alkaline solution was slowly added to the mixed salt solution under magnetic stirring to adjust the pH of the mixed metal salt solution to 9. A clean zinc plate was placed vertically in the reactor liner, the above solution was added, and the reaction was carried out at 80°C for 10 h. After the reaction, the mixture was washed with deionized water and naturally air-dried to obtain a NiAl-LDHs sample.

[0090] 0.73 g of 8-hydroxyquinoline was dissolved in 100 mL of anhydrous ethanol to prepare a corrosion inhibitor solution, and the NiAl-LDHs sample was immersed in the solution, reacted at 40° C. for 6 h, washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample;

[0091] Finally, 0.45 g of myristic acid was mixed with 100 mL of anhydrous ethanol to obtain a surface modifier solution, and the corrosion-inhibiting ion intercalation sample was immersed therein, reacted at 50° C. for 4 h, and washed and naturally air-dried to obtain a sample with corrosion-inhibiting ion intercalation and super-hydrophobicity.

[0092] Example 6

[0093] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0094] 1.41 g of nickel sulfate heptahydrate and 0.57 g of aluminum sulfate hexadecahydrate were dissolved in 100 mL of deionized water to obtain a mixed salt solution, at which the molar ratio of nickel salt to aluminum salt was about 3:1; 6 g of urea was dissolved in 200 mL of deionized water to prepare an alkaline solution, the hydroxide concentration ratio of which was about 0.5 mol / L. Under the action of magnetic stirring, the alkaline solution was slowly added to the mixed salt solution to adjust the pH of the mixed metal salt solution to 7; a clean iron plate was vertically placed in the inner tank of a reactor, and the above-obtained solution was added, and the reactor was placed at 80°C for reaction for 16 hours. After the reaction, the sample was washed with deionized water and naturally air-dried to obtain a NiAl-LDHs sample.

[0095] 1.64 g of sodium phosphate was dissolved in 100 mL of deionized water to prepare a corrosion inhibitor solution. The NiAl-LDHs sample was immersed in the corrosion inhibitor solution and reacted at 50° C. for 10 h. After completion, it was washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalated sample.

[0096] 1.35 g of stearylamine was dissolved in 100 mL of ethanol solution to obtain a surface modifier solution with a concentration of 0.05 mol / L. The sample with corrosion inhibition ion intercalation was immersed in it and reacted at 50°C for 8 hours. The obtained sample was washed and naturally air-dried to finally obtain a sample with corrosion inhibition ion intercalation and super hydrophobicity.

[0097] Example 7

[0098] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0099] Take 2.49g of nickel acetate tetrahydrate and 0.80g of aluminum chloride hexahydrate and dissolve them in 100mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 3:1, take ammonia water (25% concentration) and dilute it to make an alkaline solution with a hydroxide concentration of 0.3mol / L, slowly add the alkaline solution to the mixed salt solution under magnetic stirring, adjust the pH of the mixed metal salt solution to 7.5, place a clean magnesium plate vertically in the reactor liner, add the above solution, react at 100°C for 10h, wash with deionized water after the end and air dry naturally to obtain a NiAl-LDHs sample;

[0100] 0.82 g of ammonium molybdate was dissolved in 100 mL of deionized water to prepare a corrosion inhibitor solution, and the NiAl-LDHs sample was immersed in the solution, reacted at 60° C. for 8 h, and washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample;

[0101] Finally, 0.35 g of perfluorodecyltrimethoxysilane was mixed with 100 mL of ethanol to obtain a surface modifier solution, and the corrosion-inhibiting ion intercalation sample was immersed in it, reacted at 50° C. for 2 h, and finally, after washing and natural air drying, a sample with corrosion-inhibiting ion intercalation and super hydrophobicity was obtained.

[0102] Example 8

[0103] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0104] Take 2.38g of nickel chloride hexahydrate and 2.09g of aluminum sulfate hexahydrate and dissolve them in 100mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 1.5:1, take 5.60g of sodium hydroxide and dissolve it in 200mL of deionized water to prepare an alkaline solution with a hydroxide concentration of 0.7mol / L, slowly add the alkaline solution to the mixed salt solution under magnetic stirring, adjust the pH of the mixed metal salt solution to 8.5, place a clean copper plate vertically in the reactor liner, add the above solution, react at 120°C for 6h, and wash with deionized water and dry naturally to obtain a NiAl-LDHs sample;

[0105] 1.02 g of 8-hydroxyquinoline was dissolved in 100 mL of ethanol to prepare a corrosion inhibitor solution, and the NiAl-LDHs sample was immersed in the solution, reacted at 45°C for 7 h, and washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample;

[0106] Finally, 2.22 g of dodecyl ammonium chloride was mixed with 100 mL of n-hexane to obtain a surface modifier solution, and the corrosion-inhibiting ion intercalation sample was immersed in the solution, reacted at 60° C. for 3 h, washed and naturally air-dried, and finally a sample with corrosion-inhibiting ion intercalation and super-hydrophobicity was obtained.

[0107] Example 9

[0108] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0109] Take 5.82g of nickel nitrate nonahydrate and 5g of aluminum nitrate nonahydrate and dissolve them in 100mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 1.5:1, take 6.01g of urea and dissolve it in 200mL of deionized water to prepare an alkaline solution, slowly add the alkaline solution to the mixed salt solution under magnetic stirring, adjust the pH of the mixed metal salt solution to 7.2, place a clean iron plate vertically in the reactor liner, add the above solution, react at 90°C for 15h, wash with deionized water after the reaction and air dry naturally to obtain a NiAl-LDHs sample;

[0110] 0.94 g of sodium phosphate was dissolved in 100 mL of ethylene glycol to prepare a corrosion inhibitor solution, and the NiAl-LDHs sample was immersed in the solution, reacted at 55°C for 9 h, and washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample;

[0111] Finally, 0.62 g of oleic acid was mixed with 100 mL of toluene to obtain a surface modifier solution, and the corrosion-inhibiting ion intercalation sample was immersed in it. The solution was reacted at 70° C. for 1.5 h, and then washed and naturally air-dried to finally obtain a sample with corrosion-inhibiting ion intercalation and super-hydrophobicity.

[0112] Example 10

[0113] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0114] Take 4.85g of nickel nitrate hexahydrate and 3.13g of aluminum nitrate nonahydrate and dissolve them in 100mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 2:1, take 6.73g of potassium carbonate and dissolve it in 200mL of deionized water to prepare an alkaline solution with a hydroxide concentration of 0.6mol / L, slowly add the alkaline solution to the mixed salt solution under magnetic stirring, adjust the pH of the mixed metal salt solution to 8.0, place a clean aluminum plate vertically in the reactor liner, add the above solution, react at 110°C for 12h, and wash with deionized water and air dry naturally to obtain a NiAl-LDHs sample;

[0115] 1.12 g of 2-mercaptobenzothiazole was dissolved in 100 mL of DMF to prepare a corrosion inhibitor solution, and the NiAl-LDHs sample was immersed in the solution, reacted at 50° C. for 10 h, and washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample;

[0116] Finally, 0.53 mL of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane was mixed with 100 mL of isopropanol to obtain a surface modifier solution, in which the corrosion-inhibiting ion intercalation sample was immersed, reacted at 60°C for 2.5 h, washed and naturally air-dried, and finally a sample with corrosion-inhibiting ion intercalation and superhydrophobicity was obtained.

[0117] Embodiment 11

[0118] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0119] 4.21 g of nickel sulfate heptahydrate and 1.41 g of aluminum nitrate nonahydrate were dissolved in 100 mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 4:1. 11.22 g of potassium hydroxide was dissolved in 200 mL of deionized water to prepare an alkaline solution with a hydroxide concentration of 1.0 mol / L. The alkaline solution was slowly added to the mixed salt solution under magnetic stirring to adjust the pH of the mixed metal salt solution to 10. A clean stainless steel plate was placed vertically in the reactor liner, the above solution was added, and the reaction was carried out at 140 ° C for 5 h. After the reaction, the solution was washed with deionized water and dried naturally to obtain a NiAl-LDHs sample.

[0120] 0.69 g of sodium nitrite was dissolved in 100 mL of a water / ethanol (volume ratio 1:1) mixture to prepare a corrosion inhibitor solution, and the NiAl-LDHs sample was immersed in the solution, reacted at 35°C for 12 h, and washed with deionized water and naturally air-dried to obtain a corrosion-inhibiting ion intercalation sample;

[0121] Finally, 1.41 g of oleic acid was mixed with 100 mL of ethanol to obtain a surface modifier solution, and the corrosion-inhibiting ion intercalation sample was immersed in it. The solution was reacted at 40° C. for 6 h, and then washed and naturally air-dried to finally obtain a sample with corrosion-inhibiting ion intercalation and super-hydrophobicity.

[0122] Example 12

[0123] A method for preparing a layered double metal hydroxide anti-corrosion coating comprises the following steps:

[0124] 2.81 g of nickel sulfate heptahydrate and 3.15 g of aluminum sulfate hexadecahydrate were dissolved in 100 mL of deionized water to obtain a mixed salt solution with a molar ratio of nickel salt to aluminum salt of 2:1. 8 g of sodium hydroxide was dissolved in 200 mL of deionized water to prepare an alkaline solution with a hydroxide concentration of 1.0 mol / L. The alkaline solution was slowly added to the mixed salt solution under magnetic stirring to adjust the pH of the mixed metal salt solution to 9. A clean zinc plate was placed vertically in the inner tank of the reactor, the above solution was added, and the reaction was carried out at 90°C for 12 hours. After the reaction, it was washed with deionized water and naturally air-dried to obtain a NiAl-LDHs sample.

[0125] Take 3.06g of sodium hexametaphosphate and dissolve it in deionized water to make a 0.1mol / L solution. Immerse the sample at 60℃ for 6h, wash it with deionized water and air dry it naturally to obtain the corrosion-inhibiting ion intercalation sample;

[0126] 1.37 g of myristic acid was dissolved in ethanol to prepare a 0.06 mol / L solution. The sample was immersed in 50°C for 4 hours, washed and naturally air-dried, and finally a sample with corrosion-inhibiting ion intercalation and super-hydrophobicity was obtained.

[0127] Comparative Example 1

[0128] Example 1 was repeated except that the reaction time was changed to 2 h. The prepared NiAl-LDHs particles were significantly smaller than those prepared under normal conditions, and both the hydrophobicity and sustained release capacity were significantly reduced.

[0129] From the above, it can be seen that: due to the short hydrothermal reaction time, the crystal nuclei lack more time to grow, resulting in too few LDHs growing on the substrate surface.

[0130] Comparative Example 2

[0131] Example 1 was repeated except that stearic acid was not used in the reaction process. The prepared NiAl-LDHs lost its hydrophobicity.

[0132] From the above, we can know that: since the surface modifier can reduce the surface energy of the sample, the sample surface changes from a hydrophilic state to a hydrophobic state, and reducing the amount of the surface modifier will lead to a decrease in the amount of the modifier grafted on the NiAl-LDHs surface, thereby reducing the hydrophobicity.

[0133] Comparative Example 3

[0134] Example 1 was repeated, except that the pH of the mixed metal salt solution was adjusted to 12. The microstructure of the prepared sample changed significantly, from the original sheet-like structure to a sharp structure.

[0135] From the above, it can be seen that when the pH value is too high, the aluminum salt precipitate in the original LDHs will react with the excess hydroxide ions to generate aluminate ions, which will eventually lead to the formation of a mixture of nickel hydroxide and aluminate precipitate.

[0136] Figure 7 This is a scanning electron microscope image of the layered double metal hydroxide anti-corrosion coating prepared in Comparative Example 3.

[0137] Comparative Example 4

[0138] Example 1 was repeated except that the step of immersing the sample in sodium orthovanadate corrosion inhibitor was omitted. The prepared sample (M-LDHs) maintained a certain hydrophobicity, but the corrosion resistance decreased significantly.

[0139] Figure 8 This is the Nyquist spectrum of the layered double metal hydroxide anti-corrosion coating prepared in Comparative Example 4;

[0140] From the above, it can be seen that due to the lack of release of orthovanadate ions, the corrosion inhibition ability of the coating decreases.

[0141] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a layered double metal hydroxide anti-corrosion coating, characterized in that: The steps include: 1) dissolving a soluble first metal salt and a soluble second metal salt in deionized water to obtain a mixed salt solution; dissolving an alkali salt in deionized water to obtain an alkali solution; adjusting the pH value of the mixed salt solution with the alkali solution, and then placing the mixed salt solution and the metal substrate in a reaction kettle; 2) heating the reaction kettle to perform a hydrothermal reaction, preparing M1M2-LDHs on the surface of the metal plate, thereby obtaining a metal plate with M1M2-LDHs on the surface; 3) dissolving the corrosion inhibitor in deionized water to prepare a corrosion inhibitor solution, and placing the prepared metal plate with M1M2-LDHs on the surface in the corrosion inhibitor solution to carry out an ion exchange reaction, thereby obtaining a layered double metal hydroxide with corrosion inhibition function; 4) dissolving the surface modifier in a solvent to obtain a surfactant solution, and immersing the layered double hydroxide obtained in step 3) in the surfactant solution to obtain a super hydrophobic layered double hydroxide coating M-LDHs-X with corrosion inhibition function.

2. The method for preparing the layered double hydroxide anticorrosive coating according to claim 1, characterized in that: In step 1, the first metal salt is a soluble nickel salt, and the second metal salt is a soluble aluminum salt.

3. The method for preparing the layered double hydroxide anticorrosive coating according to claim 2, characterized in that: The soluble nickel salt is selected from one or more of the following substances: nickel iodide, nickel ammonium sulfate, nickel perchlorate, nickel nitrite, nickel acetate tetrahydrate, nickel chloride hexahydrate, nickel bromide, nickel sulfate heptahydrate, and nickel nitrate hexahydrate; the soluble aluminum salt is selected from one or more of the following substances: aluminum phosphate, aluminum bromide, aluminum citrate, ammonium aluminum sulfate, aluminum iodide, aluminum acetate, aluminum chloride hexahydrate, aluminum nitrate nonahydrate, and aluminum sulfate hexahydrate.

4. The method for preparing the layered double hydroxide anticorrosive coating according to claim 2, characterized in that: In step 1), in the mixed salt solution, the concentration of soluble nickel salt is 0.01-1 mol / L, and the molar ratio of the soluble nickel salt to the soluble aluminum salt is 1:1-4:1; the hydroxide concentration in the alkaline solution is 0.1-4 mol / L; and the pH value of the mixed salt solution is adjusted to 5-10.

5. The method for preparing the layered double hydroxide anticorrosive coating according to claim 1, characterized in that: In step 1), the alkali salt is selected from one or more of the following substances: urea, potassium hydroxide, sodium hydroxide, and ammonia water.

6. The method for preparing the layered double hydroxide anticorrosive coating according to claim 1, characterized in that: In step 1), the metal substrate is selected from one of the following: magnesium plate, iron plate, zinc plate, copper plate, and aluminum plate.

7. The method for preparing the layered double hydroxide anticorrosive coating according to claim 1, characterized in that: In step 2), the temperature of the hydrothermal reaction is 50-140°C; more preferably, the temperature of the hydrothermal reaction is 70-120°C.

8. The method for preparing the layered double hydroxide anticorrosive coating according to claim 1, characterized in that: In step 2), the hydrothermal reaction time is 6-16 h; more preferably, the hydrothermal reaction time is 8-16 h.

9. The method for preparing the layered double hydroxide anticorrosive coating according to claim 1, characterized in that: In step 3), the corrosion inhibitor is selected from one or more of the following substances: sodium phosphate, potassium phosphate, sodium hexametaphosphate, 8-hydroxyquinoline, 2-mercaptobenzothiazole, sodium nitrite, sodium molybdate, ammonium molybdate, sodium orthovanadate, sodium metavanadate; more preferably, the corrosion inhibitor is selected from one or more of the following substances: sodium phosphate, sodium hexametaphosphate, 8-hydroxyquinoline, 2-mercaptobenzothiazole, sodium nitrite, sodium molybdate, sodium orthovanadate, sodium metavanadate; Preferably, in step 3), the concentration of the corrosion inhibitor solution is 0.01-0.6 mol / L, more preferably, the concentration of the corrosion inhibitor solution is 0.05-0.5 mol / L; Preferably, in step 3), the temperature of the ion exchange reaction is 30-90°C, more preferably, the temperature of the ion exchange reaction is 40-80°C; In step 3), the ion exchange reaction time is 1-16 hours; more preferably, the ion exchange reaction time is 4-14 hours.

10. The method for preparing the layered double hydroxide anticorrosive coating according to claim 1, characterized in that: In step 4), the surface modifier is selected from one or more of the following substances: tridecafluorooctyl triethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyl trimethoxysilane, sodium laurate, myristic acid, oleic acid, stearic acid, sodium stearate, 1-aminooctadecane, dodecyl ammonium chloride; more preferably, the surface modifier is selected from one or more of the following substances: 1H, 1H, 2H, 2H-perfluorodecyl trimethoxysilane, sodium laurate, myristic acid, oleic acid, stearic acid, 1-aminooctadecane, dodecyl ammonium chloride; Preferably, in step 4), the concentration of the surface modifier is 0.01-1.0 mol / L; more preferably, the concentration of the surface modifier is: 0.05-0.6 mol / L; Preferably, in step 4), the immersion temperature is 30-90°C; more preferably, the immersion temperature is 40-80°C.

Images