Self-repairing MXene composite anticorrosive coating as well as preparation method and application thereof

Abstract

The invention relates to a self-repairing MXene composite anticorrosive coating as well as a preparation method and application thereof. The composite anticorrosive coating comprises a calcium myristate layer and tannic acid modified MXene tablets which are uniformly distributed in the calcium myristate layer. The composite anticorrosive coating is prepared through a one-step electro-deposition process. The preparation method comprises the following specific steps: pretreating the surface of a substrate; the preparation method comprises the following steps: dissolving tannic acid and MXene dispersion liquid in an ethanol solution, uniformly mixing, and centrifuging to obtain a precipitate; dissolving myristic acid and calcium chloride in an ethanol solution, and uniformly stirring to obtain a calcium myristate solution; uniformly stirring and mixing the precipitate and a calcium myristate solution in an ethanol solution to obtain a deposition solution; and carrying out electro-deposition by taking the deposition liquid as an electrolyte, taking a pretreated substrate as a cathode and taking a platinum electrode as an anode to prepare the self-repairing MXene composite anticorrosive coating. Compared with the prior art, the preparation method is simple, environmentally friendly and low in cost, and the prepared coating has good corrosion resistance and self-repairing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy surface treatment, and in particular to a self-repairing MXene composite anti-corrosion coating and a preparation method and application thereof. Background Art

[0002] In recent years, with the depletion of fossil energy, the development and utilization of clean new energy has gradually increased. The global offshore wind power installed capacity continues to increase, which has caused difficulties in the reliable and safe supply of energy for offshore wind power. In particular, in the high-salt, high-humidity and high-temperature environment of the ocean, metal corrosion will cause huge economic losses and safety hazards, and bring challenges to the operation and maintenance of offshore wind power. Therefore, new requirements are put forward for the protection of metal materials used in offshore wind power equipment. Aluminum and its alloys are widely used in marine engineering equipment, especially offshore wind power equipment, due to their low density and excellent mechanical properties. However, in the marine environment, the oxide film on the surface of aluminum alloy is easily damaged by chloride ion corrosion, and its poor corrosion resistance needs to be solved urgently. Coating protection is a direct and effective way to protect metals from corrosion. However, there are inevitably defects such as cracks and micropores in the coating, which restrict its long-term and stable anti-corrosion performance. Therefore, it is urgent to develop self-repairing anti-corrosion coatings to achieve long-term and stable protection of metal surfaces, extend the service life of metal substrate materials, and ensure the safety and reliability of metal materials in the marine environment.

[0003] Two-dimensional (2D) transition metal carbide or nitride (MXene) based composite coatings have good application prospects in the field of metal surface corrosion protection. Because 2D MXene nanosheets can reduce defects such as holes in the coating, their strong barrier properties and high aspect ratio can extend the corrosion medium (Cl - , O 2 , H 2 O) diffusion path in the coating. In addition, the rich functional groups on the MXene surface are conducive to the dispersion of MXene in the coating and its combination with other chemicals. Based on its physical structure and surface properties, MXene nanosheets can effectively improve the corrosion resistance of the coating as fillers. At present, people have adopted 2D MXene composite coatings to achieve self-healing functions.

[0004] Liu et al. developed a coprecipitation method to prepare Ce-modified 1-allyl-3-methylimidazolium bromide-Ti by forming a covalent and / or coordination network. 3 C 2 T xNanosheets are added as fillers to epoxy resin composite coatings to achieve self-healing protective properties. Chinese patent CN119101451A discloses a functionalized graphene oxide-MXene nanosheet-enhanced self-healing anti-corrosion coating, which is obtained by hydrolyzing graphene oxide-MXene nanosheets modified by a silane coupling agent containing SS bonds to obtain a two-dimensional nanomaterial. The SS bonds introduced by the silane coupling agent can enhance the self-healing efficiency of the self-healing polyurethane containing SS bonds. Chinese patent CN116555860A constructs a double-layer super-hydrophobic self-healing coating on the surface of a modified aluminum alloy with epoxy polysulfide resin and sulfonated MXene as the bottom layer and titanium dioxide, tridecafluorooctyl triethoxysilane, and polydimethylsiloxane as the surface layer, and introduces sulfonated MXene with the effect of a photothermal conversion agent to accelerate its self-healing rate.

[0005] However, simple and environmentally friendly design strategies for MXene coatings have yet to be developed, and the mechanism of MXene's action on the coating-metal interface during the self-healing process remains unclear. These methods have problems such as low efficiency, high preparation cost, environmental pollution, long time consumption, and thick coatings, and are not very suitable for practical industrial applications. Therefore, it is crucial to find a low-energy, simple, environmentally friendly, and fast preparation process to achieve efficient self-healing function in the field of metal surface protection. Summary of the invention

[0006] The purpose of the present invention is to provide a self-repairing MXene composite anti-corrosion coating and its preparation method and application. The preparation method is simple, environmentally friendly and low-cost, and the prepared coating has good corrosion resistance and self-repairing efficiency.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] On the one hand, the present invention provides a self-healing MXene composite anti-corrosion coating, comprising a calcium myristic acid layer and tannic acid modified MXene sheets, wherein the calcium myristic acid layer is disposed on a substrate surface, and the tannic acid modified MXene sheets are uniformly distributed in the calcium myristic acid layer.

[0009] Preferably, the substrate comprises a metal substrate.

[0010] Further preferably, the substrate comprises an aluminum alloy.

[0011] More preferably, the aluminum alloy is 5052 aluminum alloy.

[0012] Preferably, the MXene comprises a single layer of Ti 3 C 2 T x .

[0013] Preferably, the calcium myristic acid layer comprises calcium myristic acid, the calcium myristic acid forms a plurality of spherical agglomerates, the plurality of spherical agglomerates are piled together to form a dense layer, and the diameter of the spherical agglomerates is 7-10 μm.

[0014] Preferably, the thickness of the calcium myristate layer is 15 μm to 16 μm.

[0015] In a second aspect, the present invention further provides a method for preparing the self-repairing MXene composite anti-corrosion coating, comprising the following steps:

[0016] S1, substrate surface pretreatment;

[0017] S2, dissolving tannic acid and MXene dispersion in ethanol solution, stirring evenly to obtain a mixed solution, and centrifuging to obtain a precipitate;

[0018] S3, dissolving myristic acid and calcium chloride in an ethanol solution, and stirring to obtain a calcium myristic acid solution;

[0019] S4, stirring and mixing the precipitate prepared in step S2 and the calcium myristic acid solution obtained in step S3 in an ethanol solution to obtain a sedimentation solution;

[0020] S5. Using the deposition solution obtained in step S4 as an electrolyte, the pretreated substrate obtained in step S1 as a cathode, and a platinum electrode as an anode for electrodeposition to prepare the self-repairing MXene composite anti-corrosion coating.

[0021] Preferably, step S1 comprises the following steps: polishing the surface of the substrate, and performing ultrasonic cleaning in an ethanol solution, deionized water, and an ethanol solution in sequence to remove oil and dust from the surface of the aluminum alloy.

[0022] Further preferably, in step S1, the specific step of polishing is: polishing the substrate with 400 mesh, 1000 mesh, 1500 mesh, and 2000 mesh water-abrasive sandpaper in sequence.

[0023] Further preferably, in step S1, the ultrasonic cleaning refers to ultrasonic cleaning in an ethanol solution for 3 to 6 minutes, ultrasonic cleaning in deionized water for 3 to 6 minutes, and ultrasonic cleaning in an ethanol solution for 3 to 6 minutes.

[0024] More preferably, in step S1, the ultrasonic cleaning refers to ultrasonic cleaning in an ethanol solution for 5 minutes, ultrasonic cleaning in deionized water for 5 minutes, and ultrasonic cleaning in an ethanol solution for 5 minutes, respectively.

[0025] Preferably, in step S2, the MXene dispersion is a single layer Ti 3 C 2 T x dispersion, wherein the mixed solution contains a single layer of Ti3 C 2 T x The concentration of the tannic acid is 0.1 mg / ml to 0.3 mg / ml, and the concentration of the tannic acid is 0.001M to 0.0013M.

[0026] Further preferably, in step S2, the single layer Ti 3 C 2 T x The concentration of the dispersion is 4 to 6 mg / mL, more preferably 5 mg / mL.

[0027] Preferably, in step S2, the stirring temperature is room temperature, the stirring time is 40 to 60 minutes, and the stirring speed is 250 r / min to 350 r / min.

[0028] Further preferably, in step S2, the stirring time is 40 min and the stirring speed is 300 r / min.

[0029] Preferably, in step S2, the centrifugal time is 6 to 8 minutes, and the rotation speed is 8600 to 10000 r / min.

[0030] Further preferably, in step S2, the centrifugation time is 6 min and the rotation speed is 8600 r / min.

[0031] Preferably, in step S3, in the calcium myristic acid solution, the concentration of myristic acid is 0.1M to 0.15M, and the concentration of calcium chloride is 0.1M to 0.15M.

[0032] Preferably, in step S3, the stirring temperature is room temperature, the stirring time is 10 to 20 minutes, and the stirring speed is 250 r / min to 350 r / min.

[0033] Further preferably, in step S3, the stirring time is 15 min and the stirring speed is 300 r / min.

[0034] Preferably, in step S4, in the sedimentation liquid, the mass volume ratio of the precipitate to the calcium myristic acid solution is 1:(240-280), and more preferably 1:260.

[0035] Preferably, in step S4, the stirring temperature is room temperature, the stirring time is 10 to 20 minutes, and the stirring speed is 250 r / min to 350 r / min.

[0036] Further preferably, in step S4, the stirring time is 20 min and the stirring speed is 300 r / min.

[0037] Preferably, the volume concentration fraction of the ethanol solution in steps S2, S3 and S4 is 99.3%.

[0038] Preferably, in step S5, the voltage of the electrodeposition is 5-40V and the time is 5-40min.

[0039] Further preferably, in step S5, the voltage of the electrodeposition is 30 V and the time is 30 min.

[0040] Further preferably, in step S5, after the electrodeposition, the coating is naturally dried at room temperature to prepare the self-repairing MXene composite anti-corrosion coating.

[0041] Further preferably, the method for preparing the self-repairing MXene composite anti-corrosion coating comprises the following steps:

[0042] S1, pre-treating the substrate;

[0043] S2. preparing a deposition liquid A: adding tannic acid (TA) and MXene to an ethanol solution and stirring to obtain a deposition liquid A;

[0044] S3, placing the prepared sedimentation liquid A into a centrifuge for centrifugation to obtain a precipitate;

[0045] S4, preparing deposition liquid B: placing myristic acid and calcium chloride in an ethanol solution and stirring evenly to obtain a calcium myristic acid solution, which is deposition liquid B;

[0046] S5, preparing a sedimentation liquid C: stirring and mixing the prepared precipitate and the sedimentation liquid B in an ethanol solution to obtain a sedimentation liquid C;

[0047] S6. Connect the positive and negative poles of the potentiostat to the platinum electrode and the pretreated substrate prepared in step S1 respectively, use the deposition solution C prepared in step S5 as the electrolyte, the pretreated substrate prepared in step S1 as the cathode, and the platinum electrode as the anode for electrodeposition to obtain a self-healing MXene composite coating on the surface of the pretreated substrate.

[0048] In a third aspect, the present invention also provides an application of the self-healing MXene composite anti-corrosion coating in aluminum alloy parts.

[0049] Preferably, the aluminum alloy parts are used in the fields of ocean, petroleum, chemical industry and new energy.

[0050] Tannic acid is a natural, non-toxic, biodegradable corrosion inhibitor. Tannic acid can form a tannic acid iron multilayer film through chemical adsorption of tannic acid molecules and metal Fe, and achieve good self-repair function in near-neutral solution.

[0051] Based on the surface charge characteristics and two-dimensional nanostructure of MXene, the present invention combines the release and corrosion inhibition effect of tannic acid, and realizes the preparation of a self-repairing MXene composite anti-corrosion coating by one-step electrodeposition on a metal substrate without complex chemical modification and orientation regulation under the action of a constant potential electric field. The coating has self-repairing properties, which provides conditions for the long-term anti-corrosion effect of the coating. The self-repairing MXene composite anti-corrosion coating of the present invention can significantly improve the corrosion resistance of aluminum alloys in marine environments, so that the surface of aluminum alloys has excellent long-term corrosion resistance. In addition, the preparation time of the present invention is short (30 minutes) and the cost is low; different from traditional technologies, there is no need for orientation optimization and surface functionalization, which avoids the problem of nanomaterial agglomeration and realizes the improvement of the anti-corrosion performance of the coating; the addition of tannic acid inhibits MXene oxidation, so that the coating has self-repairing properties (the self-repairing efficiency reaches more than 99%), further improving the corrosion resistance of the coating, and can solve the corrosion problem of metal materials in marine environments.

[0052] In the present invention, the MXene composite anti-corrosion coating has a certain roughness, which makes the coating surface hydrophobic, and the contact angle can reach 147°. The anti-corrosion performance of the MXene composite coating is studied by electrochemical testing in a simulated marine environment (3.5wt.%NaCl) solution. The results show that the corrosion current density of the MXene composite coating can be reduced to 7.028×10 -9 A / cm 2 , the low-frequency impedance modulus of the MXene composite coating (|Z| 0.01Hz ) increased to 1×10 5 Ω·cm 2 The self-repair efficiency is as high as 99.53%, showing excellent self-repair performance and corrosion resistance.

[0053] In the present invention, MXene modified with tannic acid is combined with calcium myristic acid, which greatly improves the self-healing performance of the coating. After the coating is scratched by external force, tannic acid can be released on the scratched surface to achieve a self-healing effect. After the MXene composite anti-corrosion coating prepared by the present invention is treated with artificial scratches and immersed in a 3.5wt.% NaCl solution for 8 days, the corrosion current density is still as low as 1.323×10 -7 A / cm 2 , the low-frequency impedance modulus of the composite coating |Z| 0.01Hz Up to 1.79×10 5 Ω·cm 2 , which is higher than the scratch coating before immersion, achieving self-repair function. |Z| 0.01Hz It is improved by one order of magnitude compared with the blank aluminum alloy phase after pretreatment.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The present invention constructs a MXene composite anti-corrosion coating with self-healing properties on the surface of a substrate through a one-step electrodeposition process. The composite anti-corrosion coating consists of a calcium myristic acid layer and tannic acid-modified MXene sheets uniformly distributed therein. The coating has good self-healing properties and corrosion resistance, and the preparation method is simple, environmentally friendly, and low-cost.

[0056] (2) The addition of MXene in the present invention can make the composite coating have a "maze effect", prolong the diffusion path of the corrosive medium, and MXene has a negative charge that can repel Cl - 's entry, thus playing a good barrier role.

[0057] (3) In the present invention, low-cost and green tannic acid is added to inhibit MXene oxidation, so that the coating has self-healing properties. The scratched coating begins to show self-healing behavior after immersion for 5 days. After immersion for 8 days, there is obvious self-healing phenomenon at the scratch, and the self-healing efficiency reaches more than 99%. After immersion for 31 days, it still has good anti-corrosion performance.

[0058] (4) In the present invention, the addition of tannic acid also makes MXene more tightly combined with the calcium myristic acid layer. MXene can be evenly distributed in the calcium myristic acid layer instead of on its surface, making the coating denser, further enhancing its barrier properties and extending the diffusion path of the corrosive medium in the composite coating.

[0059] (5) The present invention is prepared by a one-step electrodeposition process, with a short preparation time (30 min), a simple preparation method, and no need for orientation optimization and surface functionalization, which can avoid the problem of nanomaterial agglomeration and further improve the anti-corrosion performance of the coating.

[0060] (6) The composite anti-corrosion coating of the present invention has a certain roughness, which makes the coating surface hydrophobic. The coating is thin and has little effect on the performance of aluminum alloy parts. The porosity of the MXene composite coating is 1.826×10 -5 , it has high anti-corrosion performance and self-repairing efficiency, and can be widely used in the preparation of protective coatings on the surfaces of metal substrates such as aluminum alloys.

[0061] (7) The preparation method of the present invention is simple, the preparation conditions are mild, the time is short, the cost is low, the stability is high, and it is green and environmentally friendly. A MXene composite coating is prepared on the surface of a substrate such as an aluminum alloy, which extends the service life of the aluminum alloy. It has very excellent corrosion resistance and is suitable for industrial production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a surface morphology image of a blank aluminum alloy pretreated in the present invention at 1000 times magnification by a field emission scanning electron microscope (FE-SEM);

[0063] Figure 2 This is a field emission scanning electron microscope (FE-SEM) surface morphology image of the calcium myristic acid coating in Comparative Example 1 of the present invention at 1000 times magnification;

[0064] Figure 3 This is a surface morphology image of a MXene composite coating without tannic acid modification in Comparative Example 2 of the present invention at 1000 times magnification by a field emission scanning electron microscope (FE-SEM);

[0065] Figure 4 This is a surface morphology image of the MXene composite coating modified with tannic acid in Example 1 of the present invention at 1000 times magnification by a field emission scanning electron microscope (FE-SEM);

[0066] Figure 5 XRD spectra of the calcium myristic acid coating in Comparative Example 1 of the present invention, the MXene composite coating without tannic acid modification in Comparative Example 2, and the MXene composite coating modified with tannic acid in Example 1;

[0067] Figure 6 Potentiodynamic polarization curves of the calcium myristic acid coating in Comparative Example 1 of the present invention, the MXene composite coating without tannic acid modification in Comparative Example 2, the blank aluminum alloy after pretreatment in Comparative Example 3, and the MXene composite coating modified with tannic acid in Example 1 under a simulated marine environment (3.5wt.% NaCl solution);

[0068] Figure 7 The electrochemical impedance spectroscopy Nyquist plots of the calcium myristic acid coating in Comparative Example 1 of the present invention, the MXene composite coating without tannic acid modification in Comparative Example 2, the blank aluminum alloy after pretreatment in Comparative Example 3, and the MXene composite coating modified with tannic acid in Example 1 obtained in a simulated marine environment (3.5wt.% NaCl solution);

[0069] Figure 8 This is the Nyquist plot of the electrochemical impedance spectrum obtained by the long-term immersion experiment of the tannic acid-modified MXene composite coating in Example 1 of the present invention in a simulated marine environment (3.5wt.% NaCl solution);

[0070] Fig. 9 This is a water contact angle diagram of the surface of the MXene composite coating modified with tannic acid in Example 1 of the present invention;

[0071] Fig.10Field emission scanning electron microscope (FE-SEM) surface morphology and element percentages of the calcium myristic acid coating in Comparative Example 1 of the present invention, the MXene composite coating without tannic acid modification in Comparative Example 2, the blank aluminum alloy after pretreatment in Comparative Example 3, and the MXene composite coating modified with tannic acid in Example 1 before and after artificial scratching and immersion in 3.5wt.% NaCl solution for 8 days at 1000 times magnification;

[0072] These include: after artificial scratching (a 1 ) Blank aluminum alloy; (b 1 ) calcium myristate coating; (c 1 ) MXene composite coating without tannic acid modification; (d 1 ) Surface morphology of MXene composite coating modified with tannic acid;

[0073] After artificial scratching and immersion in NaCl solution for 8 days (a 2 ) Blank aluminum alloy; (b 2 ) calcium myristate coating; (c 2 ) MXene composite coating without tannic acid modification; (d 2 ) Surface morphology of MXene composite coating modified with tannic acid;

[0074] After artificial scratching (a 3 ) Blank aluminum alloy; (b 3 ) calcium myristate coating; (c 3 ) MXene composite coating without tannic acid modification; (d 3 ) Atomic percentage of tannic acid modified MXene composite coating;

[0075] After artificial scratching and immersion in NaCl solution for 8 days (a 4 ) Blank aluminum alloy; (b 4 ) calcium myristate coating; (c 4 ) MXene composite coating without tannic acid modification; (d 4 ) Atomic percentage of tannic acid modified MXene composite coating;

[0076] Fig.11 (ac) blank aluminum alloy with artificial scratches in the present invention; (df) calcium myristic acid coating; (gi) MXene composite coating without tannic acid modification; (jl) electrochemical impedance spectroscopy Bode diagram, phase angle diagram and Nyquist diagram obtained by immersion test of MXene composite coating modified with tannic acid in simulated marine environment (3.5wt.% NaCl solution);

[0077] Fig.12Potentiodynamic polarization curves of the calcium myristate coating in Comparative Example 1 after artificial scratch treatment, the MXene composite coating without tannic acid modification in Comparative Example 2, the blank aluminum alloy after pretreatment in Comparative Example 3, and the MXene composite coating modified with tannic acid in Example 1 after immersion in 3.5 wt.% NaCl solution for 8 days. DETAILED DESCRIPTION

[0078] This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0079] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0080] The present invention provides a self-repairing MXene composite anti-corrosion coating, comprising a calcium myristic acid layer and a tannic acid-modified MXene sheet, wherein the calcium myristic acid layer is arranged on a substrate surface, and the tannic acid-modified MXene sheet is uniformly distributed in the calcium myristic acid layer.

[0081] The preparation method includes the following steps:

[0082] S1, substrate surface pretreatment;

[0083] S2, dissolving tannic acid and MXene dispersion in ethanol solution, stirring evenly to obtain a mixed solution, and centrifuging to obtain a precipitate;

[0084] S3, dissolving myristic acid and calcium chloride in an ethanol solution, and stirring to obtain a calcium myristic acid solution;

[0085] S4, stirring and mixing the precipitate prepared in step S2 and the calcium myristic acid solution obtained in step S3 in an ethanol solution to obtain a sedimentation solution;

[0086] S5. Using the deposition solution obtained in step S4 as an electrolyte, the pretreated substrate obtained in step S1 as a cathode, and a platinum electrode as an anode for electrodeposition to prepare the self-repairing MXene composite anti-corrosion coating.

[0087] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. The various chemicals and raw materials used in the following examples are commercially available products, as follows:

[0088] The 5052 aluminum alloy plate (40×13×3 mm) used in the present invention was purchased from Shenzhen Hongwang Mould Co., Ltd., myristic acid (>98%), calcium chloride (>96%) and tannic acid (>95%) were purchased from Titan Technology Co., Ltd., and 5 mg / mL Ti 3 C 2T x MXene was purchased from Jilin Yiyi Technology Co., Ltd. (Jilin Province, China). All solvents and chemicals were of analytical grade and used as received.

[0089] The method for detecting performance in the following embodiments is as follows:

[0090] The present invention uses a field emission scanning electron microscope (FE-SEM, JEOL, JSM-7800F, Japan) at 5 kV to observe the surface morphology of the sample. A contact angle meter (JC 2000D5, Shanghai Zhongchen Digital Technology Instrument Co., Ltd.) is used to measure the contact angle of water droplets (5 μL) on different samples at room temperature.

[0091] Electrochemical tests of various samples were performed on an electrochemical workstation (CHI600E, Shanghai Chenhua Instrument Co., Ltd., China) in a simulated marine environment (3.5wt.% NaCl solution). Before testing, the samples were immersed in 3.5wt.% NaCl solution to obtain a stable open circuit voltage (OCP). Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve tests were performed in a three-electrode system. The aluminum alloy after sealing (sample area of ​​1cm 2 ) as the working electrode, platinum as the counter electrode, and saturated calomel electrode as the reference electrode. For EIS testing, the frequency was set to 10 5 ~10 -2 Hz, with an amplitude of 5 mV. The equivalent circuit was fitted using ZSimpWin software. The scanning range of the potentiodynamic polarization test was E±300 mV (vs. SCE), and the scanning speed was 1 mV / s. The protection efficiency (η 1 %):

[0092]

[0093] Among them I corr(Bare Al alloy) and I corr(coating) are the corrosion current densities of blank aluminum alloy and coating samples, respectively.

[0094] Example 1

[0095] This embodiment provides a method for preparing a self-repairing MXene composite anti-corrosion coating, and the specific steps are as follows:

[0096] 1) Pre-treat aluminum alloy. The specific steps are as follows:

[0097] The 5052 aluminum alloy was polished with 400 mesh, 1000 mesh, 1500 mesh and 2000 mesh water-abrasive sandpaper in sequence. The polished aluminum alloy was placed in an ethanol solution for ultrasonic cleaning, and then ultrasonically cleaned with deionized water and anhydrous ethanol for about 15 minutes in sequence to remove oil and dust on the surface of the aluminum alloy.

[0098] 2) Prepare deposition solution A, the specific steps are as follows:

[0099] Weigh 0.06g of tannic acid and 1mL of 5mg / mL Ti 3 C 2 T x The MXene dispersion was added to 30 mL of ethanol solution, and the solution was stirred evenly until complete alcoholysis was obtained to obtain deposition solution A;

[0100] 3) Preparing precipitation, the specific steps are as follows:

[0101] Place sedimentation liquid A in a centrifuge tube and centrifuge it for 6 minutes at a speed of 8600 r / min. The supernatant is introduced into a waste liquid pool, leaving the sediment.

[0102] 4) Prepare deposition solution B, the specific steps are as follows:

[0103] Weigh 1.37 g of myristic acid and 0.67 g of calcium chloride particles into 60 mL of ethanol solution, stir and mix to obtain sedimentation solution B;

[0104] 5) Prepare deposition solution C, the specific steps are as follows:

[0105] The precipitate prepared in step 3) is added to the sedimentation liquid B prepared in step 4), and stirred for 20 minutes to obtain sedimentation liquid C;

[0106] 6) Prepare MXene composite coating, the specific steps are as follows:

[0107] The positive and negative poles of the potentiostat are respectively connected to the pretreated blank aluminum alloy and the platinum electrode prepared in step 1) (wherein the pretreated blank aluminum alloy is used as the cathode / negative electrode and the platinum electrode is used as the anode / positive electrode), placed in the deposition solution prepared in step 5), the voltage is set to 30 V, the time is set to 30 min, the electrodeposition is completed, and it is naturally dried at room temperature to obtain a complete, stable and strongly bonded MXene composite coating on the surface of the pretreated blank aluminum alloy.

[0108] Comparative Example 1

[0109] This comparative example provides a calcium myristic acid coating, and the preparation process and experimental parameters are consistent with those of Example 1. Different from Example 1, tannic acid and MXene dispersion are not added during the preparation of the calcium myristic acid coating.

[0110] The specific preparation process is as follows:

[0111] 1) Pre-treat aluminum alloy. The specific steps are as follows:

[0112] The 5052 aluminum alloy was polished with 400 mesh, 1000 mesh, 1500 mesh and 2000 mesh water-abrasive sandpaper in sequence. The polished aluminum alloy was placed in an ethanol solution for ultrasonic cleaning, and then ultrasonically cleaned with deionized water and anhydrous ethanol for about 15 minutes in sequence to remove oil and dust on the surface of the aluminum alloy.

[0113] 2) Prepare the deposition solution, the specific steps are as follows:

[0114] Weigh 1.37 g of myristic acid and put it into 60 mL of ethanol solution, weigh 0.67 g of calcium chloride particles and put it into 60 mL of ethanol solution, stir until complete alcoholysis, and obtain a sediment solution;

[0115] 3) Preparation of MXene composite coating, the specific steps are as follows:

[0116] The positive and negative poles of the potentiostat are respectively connected to the pretreated blank aluminum alloy and the platinum electrode prepared in step 1) (wherein the pretreated blank aluminum alloy is used as the cathode / negative electrode and the platinum electrode is used as the anode / positive electrode), placed in the deposition solution prepared in step 2), the voltage is set to 30V, the time is set to 30min, the electrodeposition is completed, and it is naturally dried at room temperature to obtain a complete, stable and strongly bonded MXene composite coating on the surface of the pretreated blank aluminum alloy.

[0117] Comparative Example 2

[0118] This comparative example provides a MXene composite coating without tannic acid modification, and the preparation process and experimental parameters are consistent with those of Example 1. Different from Example 1, tannic acid is not added during the preparation of the MXene composite coating without tannic acid modification.

[0119] The specific preparation process is as follows:

[0120] 1) Pre-treat aluminum alloy. The specific steps are as follows:

[0121] The 5052 aluminum alloy was polished with 400 mesh, 1000 mesh, 1500 mesh and 2000 mesh water-abrasive sandpaper in sequence. The polished aluminum alloy was placed in an ethanol solution for ultrasonic cleaning, and then ultrasonically cleaned with deionized water and anhydrous ethanol for about 15 minutes in sequence to remove oil and dust on the surface of the aluminum alloy.

[0122] 2) Prepare deposition solution A, the specific steps are as follows:

[0123] Measure 1mL of 5mg / mL Ti 3 C 2T x The MXene dispersion was added to 30 mL of ethanol solution, and the solution was stirred evenly until complete alcoholysis was obtained to obtain deposition solution A;

[0124] 3) Preparing precipitation, the specific steps are as follows:

[0125] Place sedimentation liquid A in a centrifuge tube and centrifuge it for 6 minutes at a speed of 8600 r / min. The supernatant is introduced into a waste liquid pool, leaving the sediment.

[0126] 4) Prepare deposition solution B, the specific steps are as follows:

[0127] Weigh 1.37 g of myristic acid and put it into 60 mL of ethanol solution, weigh 0.67 g of calcium chloride particles and put it into 60 mL of ethanol solution, stir the two solutions separately and mix them, and stir until they are completely alcoholyzed to obtain sedimentation solution B;

[0128] 5) Prepare deposition solution C, the specific steps are as follows:

[0129] The precipitate prepared in step 3) is added to the sedimentation liquid B prepared in step 4), and stirred for 20 minutes to obtain sedimentation liquid C;

[0130] 6) Prepare MXene composite coating, the specific steps are as follows:

[0131] The positive and negative poles of the potentiostat are respectively connected to the pretreated blank aluminum alloy and the platinum electrode prepared in step 1) (wherein the pretreated blank aluminum alloy is used as the cathode / negative electrode and the platinum electrode is used as the anode / positive electrode), placed in the deposition solution prepared in step 5), the voltage is set to 30 V, the time is set to 30 min, the electrodeposition is completed, and it is naturally dried at room temperature to obtain a complete, stable and strongly bonded MXene composite coating on the surface of the pretreated blank aluminum alloy.

[0132] Comparative Example 3

[0133] The preparation process of the blank aluminum alloy after pretreatment is as follows:

[0134] The 5052 aluminum alloy was polished with 400 mesh, 1000 mesh, 1500 mesh and 2000 mesh water-abrasive sandpaper in sequence. The polished aluminum alloy was placed in an ethanol solution for ultrasonic cleaning, and then ultrasonically cleaned with deionized water and anhydrous ethanol for about 15 minutes in sequence to remove oil and dust on the surface of the aluminum alloy.

[0135] The surface morphology of the blank aluminum alloy after pretreatment is shown in the field emission scanning electron microscope (FE-SEM) at 1000 times magnification. Figure 1 As shown, some scratches can be observed on the surface of the blank aluminum alloy after pretreatment, but no other obvious morphology.

[0136] Figure 2 This is a field emission scanning electron microscope (FE-SEM) surface morphology of the calcium myristic acid coating in Comparative Example 1 of the present invention at 1000 times magnification, as shown in FIG. Figure 2 As shown, in the surface morphology of the calcium myristic acid coating, it can be seen that the coating structures overlap and slightly agglomerate to form a dense layer covering the surface, but the surface of the coating has some structural defects such as cracks and holes.

[0137] Figure 3 This is a surface morphology of the MXene composite coating without tannic acid modification in Comparative Example 2 of the present invention at 1000 times the field emission scanning electron microscope (FE-SEM), as shown in FIG. Figure 3 As shown, in the composite coating without adding tannic acid, a flaky structure is formed on the surface, but the coating surface has a small amount of structural defects such as cracks and holes.

[0138] Figure 4 This is a field emission scanning electron microscope (FE-SEM) surface morphology of the tannic acid-modified MXene composite coating in Example 1 of the present invention at 1000 times magnification, as shown in FIG. Figure 4 As shown, in the MXene composite coating with added tannic acid, the interaction between tannic acid and MXene makes the coating denser. Figure 4 In the sample, calcium myristic acid forms spherical aggregates, which accumulate together to form a dense layer; MXene modified with tannic acid is evenly distributed in the calcium myristic acid coating, effectively blocking the penetration of corrosive media. The sample with MXene added has a "maze effect", which prolongs the diffusion path of the corrosive medium. MXene has a negative charge that can repel Cl - The entry of MXene can be blocked, thus playing a good barrier role. The sample with added tannic acid can react with external corrosive media such as water, reduce the oxidation process of MXene, and cooperate with MXene to make the coating have a good self-healing effect.

[0139] Figure 5 These are the XRD spectra of calcium myristic acid coating, MXene composite coating without tannic acid modification, and MXene composite coating modified with tannic acid. The peaks in the figure are all characteristic peaks of calcium myristic acid, indicating that calcium chloride reacts with myristic acid to generate calcium myristic acid.

[0140] Performance Testing

[0141] Electrochemical tests were performed on the blank aluminum alloy after pretreatment of Comparative Example 3, the tannic acid modified MXene composite coating prepared in Example 1, the calcium myristic acid coating prepared in Comparative Example 1, and the tannic acid-free MXene composite coating prepared in Comparative Example 2. The results are as follows:

[0142] Figure 6 , 7Potentiodynamic polarization curves and Nyquist plots in electrochemical impedance spectroscopy were obtained by testing the pretreated blank aluminum alloy, calcium myristic acid coating, MXene composite coating without tannic acid modification and MXene composite coating modified with tannic acid in 3.5wt.% NaCl solution.

[0143] The porosity calculation formula is as follows:

[0144]

[0145] R BareAl is the polarization resistance of bare Al; R p is the polarization resistance of the coating system; ΔE corr is the corrosion potential difference between the coating sample and bare Al, β Bare Al is the Tafel slope of the bare aluminum anode. p The value can be derived from the linear polarization data using the following formula:

[0146]

[0147] β a is the anodic Tafel slope of the coating sample, β c is the cathodic Tafel slope of the coated sample.

[0148] Depend on Figure 6 Various parameters can be obtained. After calculation, it is found that the porosity of the tannic acid modified MXene composite coating of Example 1 of the present invention is 1.826×10 -5 , lower porosity can further enhance the overall corrosion resistance of the coating.

[0149] Table 1 shows the blank aluminum alloy, calcium myristic acid coating, MXene composite coating without tannic acid modification and MXene composite coating modified with tannic acid after pretreatment in the present invention according to the polarization curve ( Figure 6 ) obtained electrochemical parameters. It can be seen from Table 1 that the corrosion current density of the MXene composite coating can reach 7.028×10-9A / cm 2 , which is 3 orders of magnitude lower than that of the blank aluminum alloy after pretreatment, and the protection efficiency is as high as 99.85%. Figure 7 ) It can be seen that the tannic acid modified MXene composite coating has the largest capacitive reactance arc, which exceeds the control coating and the blank aluminum alloy after pretreatment, which can further prove that the tannic acid modified MXene composite coating has excellent corrosion resistance.

[0150] Table 1 Electrochemical parameters obtained from polarization curves

[0151] sample <![CDATA[E corr (mV)]]> <![CDATA[I corr (A / cm 2 )]]> <![CDATA[η 1 (%)]]> Comparative Example 1 -1230 <![CDATA[9.303×10 -8 ]]> 97.98％ Comparative Example 2 -1256 <![CDATA[7.584×10 -8 ]]> 98.35％ Comparative Example 3 -737 <![CDATA[4.606×10 -6 ]]> - Example 1 -630 <![CDATA[7.028×10 -9 ]]> 99.85％

[0152] The aluminum alloy sample with MXene composite coating in Example 1 was immersed in 3.5wt.% NaCl solution and subjected to electrochemical impedance spectroscopy. The electrochemical data obtained are as follows: Figure 8 As shown. The solid line is the fitting data diagram of the sample. It can be seen from the figure that after immersion in NaCl solution for 5 days, the low-frequency impedance modulus corresponding to 0.01Hz drops to 3.16×10 4 Ω·cm 2 . It dropped to the lowest value on the 7th day, but then the low-frequency impedance modulus slowly increased. On the 31st day, the impedance modulus basically recovered to the value of the first day of immersion. The results of the 30-day long-term immersion experiment in 3.5wt.% NaCl solution proved that the MXene composite coating has good long-term corrosion resistance. Through the study of the wettability of the surface of the MXene composite coating, its contact angle was measured to reach 147°( Fig. 9 ).

[0153] Self-healing performance test of coating after artificial scratch treatment

[0154] The blank aluminum alloy pretreated in Comparative Example 3, the tannic acid modified MXene composite coating prepared in Example 1, the calcium myristic acid coating prepared in Comparative Example 1, and the tannic acid-free MXene composite coating prepared in Comparative Example 2 were artificially scratched and then immersed in a 3.5wt.% NaCl solution to observe the changes in the surface morphology and chemical composition of the aluminum alloy, Example 1, Comparative Example 1, and Comparative Example 2. The results are as follows:

[0155] like Fig.10 (a 1 ,a 2 ) shows that after being artificially scratched, the blank aluminum alloy has a large amount of corrosion products on its surface after being immersed for 8 days, indicating that the corrosive medium causes the corrosion of the aluminum alloy; Fig.10 (a 3 ,a 4 ) shows that the atomic percentage of Al on the sample surface decreases after immersion, which is due to the presence of a large amount of corrosion products on the surface;

[0156] Fig.10 (b 1 , b 2 ) is the surface morphology of the calcium myristic acid coating after artificial scratching before and after immersion for 8 days. After immersion, a small amount of corrosion products were found on the surface, and there was no self-repairing effect at the surface scratches, and the surface coating peeled off; Fig.10 (b 3 ,b 4 ) shows that the atomic percentage of Al on the sample surface after immersion is reduced, which also indicates that there are a large number of corrosion products on the surface;

[0157] Fig.10 (c 1 , c 2 ) is the surface morphology of the MXene composite coating without tannic acid modification after artificial scratching before and after 8 days of immersion. It is found that the introduction of MXene improves the density of the coating, and there are fewer surface corrosion products after immersion, but there is no self-healing effect on the surface scratches; Fig.10 (c 3 ,c 4 ) shows that the addition of MXene makes the coating more compact, and the surface element composition does not change much before and after immersion;

[0158] Fig.10 (d 1 , d 2 ) is the surface morphology of the tannic acid-modified MXene composite coating after artificial scratching before and after 8 days of immersion. After immersion, it is found that the scratch is covered, indicating that tannic acid is released into the scratch under the stimulation of the scratch, making the coating have a self-healing effect; Fig.10 (d 3 ,d 4 ), after the coating self-repairs, the Al substrate exposed at the scratches is covered, so the Al content on the surface is reduced after self-repair.

[0159] Fig.11 The electrochemical impedance spectroscopy (EIS) graphs of four artificially scratched samples, including blank aluminum alloy, calcium myristic acid coating, MXene composite coating without tannic acid modification, and MXene composite coating modified with tannic acid, were subjected to long-term immersion experiments in a simulated marine environment (3.5wt.% NaCl solution). It can be seen that after 8 days of immersion, the low-frequency impedance modulus |Z| of the MXene composite coating modified with tannic acid decreased. 0.01Hz Rise 1.79×10 5 Ω·cm 2 , recovered to above the value after immersion for 12 h, proving that the tannic acid-modified MXene composite coating has self-healing function.

[0160] The coating self-repair efficiency (η) was calculated according to the following formula: 2 %):

[0161]

[0162] Where Z 0.01HZ-12h and Z 0.01Hz-192hThe low-frequency impedance modulus values ​​of the artificially scratched coating samples after immersion in 3.5wt.% NaCl solution for 12h and 192h, respectively. The self-healing efficiency of the tannic acid-modified MXene composite coating was calculated to be 99.35%. The tannic acid-modified MXene composite coating has the largest capacitive reactance arc, far exceeding the comparison coating and the blank aluminum alloy after pretreatment, which can further prove that the tannic acid-modified MXene composite coating has excellent corrosion resistance.

[0163] Fig.12 Potentiodynamic polarization curves of blank aluminum alloy, calcium myristic acid coating, MXene composite coating without tannic acid modification and MXene composite coating modified with tannic acid after artificial scratching immersed in 3.5wt.% NaCl solution for 8 days;

[0164] Table 2 shows the blank aluminum alloy, calcium myristic acid coating, MXene composite coating without tannic acid modification and MXene composite coating modified with tannic acid after pretreatment in the present invention according to the polarization curve ( Fig.12 ) obtained. As shown in Table 2, the corrosion current density of the tannic acid modified MXene composite coating after artificial scratching is still as low as 1.323×10 -7 A / cm 2 , which is lower than the corrosion current density of blank aluminum alloy, calcium myristic acid coating and MXene composite coating without tannic acid modification. Therefore, even after artificial scratch treatment, the MXene composite coating modified with tannic acid still exhibits excellent corrosion resistance.

[0165] Table 2 Electrochemical parameters obtained from polarization curves

[0166] sample <![CDATA[E corr (mV)]]> <![CDATA[I corr (A / cm 2 )]]> Comparative Example 1 -1003 <![CDATA[1.310×10 -6 ]]> Comparative Example 2 -743 <![CDATA[4.474×10 -7 ]]> Comparative Example 3 -743 <![CDATA[8.152×10 -6 <!-- 10 -->]]> Example 1 -832 <![CDATA[1.323×10 -7 ]]>

[0167] In summary, the present invention prepares a self-healing MXene composite anti-corrosion coating, which includes a calcium myristic acid layer arranged on the surface of a substrate and tannic acid-modified MXene sheets uniformly distributed in the calcium myristic acid layer. The composite anti-corrosion coating has good corrosion resistance and self-healing properties, and can be used in the preparation of protective coatings on metal substrate surfaces.

[0168] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A self-repairing MXene composite anti-corrosion coating, characterized in that: It includes a calcium myristic acid layer and a tannic acid modified MXene sheet, wherein the calcium myristic acid layer is arranged on the surface of a substrate, and the tannic acid modified MXene sheet is uniformly distributed in the calcium myristic acid layer.

2. A self-repairing MXene composite anti-corrosion coating according to claim 1, characterized in that: The substrate includes an aluminum alloy, and the MXene includes a single layer of Ti3C2T x .

3. The self-repairing MXene composite anti-corrosion coating according to claim 1, characterized in that: The calcium myristic acid layer comprises calcium myristic acid, and the calcium myristic acid forms a plurality of spherical agglomerates, and the plurality of spherical agglomerates are piled together to form a dense layer, and the diameter of a single spherical agglomerate is 7-10 μm.

4. The self-repairing MXene composite anti-corrosion coating according to claim 1, characterized in that: The thickness of the calcium myristic acid layer is 15 μm to 16 μm.

5. A method for preparing a self-repairing MXene composite anti-corrosion coating according to any one of claims 1 to 4, characterized in that: The steps include: S1, substrate surface pretreatment; S2, dissolving tannic acid and MXene dispersion in ethanol solution, stirring evenly to obtain a mixed solution, and centrifuging to obtain a precipitate; S3, dissolving myristic acid and calcium chloride in an ethanol solution, and stirring to obtain a calcium myristic acid solution; S4, stirring and mixing the precipitate prepared in step S2 and the calcium myristic acid solution obtained in step S3 in an ethanol solution to obtain a sedimentation solution; S5. Using the deposition solution obtained in step S4 as an electrolyte, the pretreated substrate obtained in step S1 as a cathode, and a platinum electrode as an anode for electrodeposition to prepare the self-repairing MXene composite anti-corrosion coating.

6. The method for preparing a self-repairing MXene composite anti-corrosion coating according to claim 5, characterized in that: Step S1 includes the following steps: polishing the surface of the substrate, and performing ultrasonic cleaning in an ethanol solution, deionized water, and an ethanol solution in sequence.

7. The method for preparing a self-repairing MXene composite anti-corrosion coating according to claim 5, characterized in that: In step S2, the MXene dispersion is a single layer Ti3C2T x dispersion, the mixed solution, a single layer Ti3C2T x The concentration of is 0.1mg / ml to 0.3mg / ml, and the concentration of tannic acid is 0.001M to 0.0013M; In step S3, in the calcium myristic acid solution, the concentration of myristic acid is 0.1M to 0.15M, and the concentration of calcium chloride is 0.1M to 0.15M.

8. The method for preparing a self-repairing MXene composite anti-corrosion coating according to claim 5, characterized in that: In step S4, in the sedimentation liquid, the mass volume ratio of the precipitate to the calcium myristic acid solution is 1:(240-280).

9. The method for preparing a self-repairing MXene composite anti-corrosion coating according to claim 5, characterized in that: In step S5, the voltage of the electrodeposition is 5-40V and the time is 5-40min.

10. Use of the self-repairing MXene composite anti-corrosion coating as claimed in any one of claims 1 to 4 in aluminum alloy parts.

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