Intelligent response aluminum alloy anticorrosive coating and preparation method thereof

Abstract

The invention discloses an intelligent response aluminum alloy anticorrosive coating and a preparation method thereof.The preparation method comprises the steps that firstly, a template agent is dissolved in deionized water, a silicon source is added after the PH of the solution is adjusted, and white precipitates are heated and refluxed to obtain MSNs; secondly, performing in-situ generation of a porous urchin-shaped MOFs material on the surface of the MSNs through a hydrothermal method and a freeze-drying method to obtain porous urchin-shaped MOFs / MSNs; then adding the MOFs / MSNs into a solution containing a corrosion inhibitor to obtain MOFs / MSNs loaded with the corrosion inhibitor; and finally, adding the corrosion inhibitor loaded MOFs / MSNs into a PDMS diluent, and coating the surface of the aluminum alloy with the mixture through a spin-coating method to obtain the aluminum alloy anticorrosive coating. The coating has excellent chemical stability, environmental responsiveness and structural integrity, and has wide application prospects in the fields of aerospace, ship engineering, electronic and electrical products, daily consumer goods and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of aluminum alloy anti-corrosion coatings, and particularly relates to an intelligent response aluminum alloy anti-corrosion coating and a preparation method thereof. Background Art

[0002] Aluminum alloy is a metal material with superior performance. It has light weight, high strength, excellent processing performance and outstanding casting performance. It is widely used in aerospace, transportation, construction and daily necessities. Depending on the environment in which the aluminum alloy is used, the aluminum alloy will suffer from different degrees of corrosion. When the aluminum alloy is exposed to the outdoor atmosphere for a long time, dust ions will be deposited on the surface of the aluminum alloy. In the water film environment containing dust ions, an oxygen-deficient zone will form on the metal surface, resulting in the destruction of the passivation film on the surface of the aluminum alloy and the decrease of self-passivation ability, forming local pitting corrosion. When in the marine atmosphere, Cl - Seawater has a strong destructive effect on the passive film on the surface of aluminum alloys. The passive state of aluminum alloys in seawater is unstable, leading to localized corrosion. According to statistics, the average pitting depth of aluminum alloys in 2020, under different corrosive environments, was 10-55mm in rural areas, 100-190mm in urban areas, and 85-260mm in marine environments. Corrosion of aluminum alloys not only affects their aesthetics but also reduces their strength and service life, even posing a threat to their safety. Therefore, addressing the issue of aluminum alloy corrosion prevention is urgent.

[0003] At present, the most common methods for aluminum alloy corrosion protection are surface treatment technologies such as micro-arc oxidation, anodizing and electroplating, but these methods are difficult to operate, costly, and the surface protective layer will lose its protective effect after being damaged. In recent years, polydimethylsiloxane (PDMS) has significant advantages in aluminum alloy corrosion protection, including super hydrophobicity, excellent corrosion resistance, self-repairing ability, self-cleaning performance and strong environmental adaptability. These characteristics make PDMS coating have broad application prospects in the field of aluminum alloy corrosion protection. However, PDMS coating is an organic coating. In high wear or high impact environments, its mechanical stability and wear resistance are relatively weak, resulting in damage to the coating and loss of its protective effect on aluminum alloys. At the same time, PDMS has a strong effect on Cl - The anti-corrosion performance of Cl is limited and it is difficult to maintain stability in the marine environment. Therefore, the researchers filled the inorganic nanocontainer into PDMS and loaded the corrosion inhibitor into the inorganic nanocontainer to construct Cl - A responsive release system was used to prepare an anti-corrosion and super-hydrophobic aluminum alloy anti-corrosion coating.

[0004] Mesoporous SiO2 nanoparticles (MSNs) are a type of nanomaterial with a unique mesoporous structure. The pore size ranges from 2 to 50 nm, the pore structure is ordered, the specific surface area is large, the pore volume is high, and the surface is easy to functionalize. In situ synthesis is a method of generating the desired functional material directly on the surface or inside the substrate during the material preparation process. Its core feature is that the reactants react chemically on the substrate under specific conditions to generate the target material, thereby achieving uniform distribution and tight bonding of the material, and the interface bonding strength is high. Generating MOFs materials on the surface of MSNs by in situ synthesis can not only use MOFs as a "bridge" to improve the bonding force between MSNs and PDMS, but also increase the surface roughness of the nanoparticles and improve the hydrophobic properties of the material. At the same time, the corrosion inhibitor is loaded in the pores of MOFs and the mesopores of MSNs, and the Cl - The influence of MOFs structure and pores and its complexation with corrosion inhibitors to achieve Cl - Intelligent response releases corrosion inhibitors, enabling the preparation of Cl-resistant - Smart Response Coatings for Corrosion.

[0005] Xia et al. (Ruohan Xia, Bing Zhang, et al. HD-SiO2 / SiO2Sol@PDMS Superhydrophobic Coating with Good Durability and Anti-Corrosion for Protection of Al Sheets [J]. Materials, 2023, 16(3532): 1-12) used hexadecyltrimethoxysilane (HDTMS) to modify SiO2 nanoparticles and acid-catalyzed silica sol to form a binary gradient micro-nanostructure (HD-SiO2 / SiO2Sol). The nanostructure was then mixed with polydimethylsiloxane (PDMS) as a binder to prepare a coating with excellent corrosion resistance on the surface of aluminum sheets. However, under high wear or high impact conditions, the coating was damaged by the impact force, and the binary gradient micro-nanostructure in the damaged area was destroyed, resulting in a decrease in the corrosion resistance of the coating in that area.

[0006] Huang Yi et al. (Huang Yi, Li Yue, Wu Chunchun, Zhao Chenyang, Shen Tao, Cheng Di, Yang Hui. Preparation and corrosion resistance of SiO2 ceramic coating on 2024 aluminum alloy surface [J]. Journal of Materials Science and Engineering, 2022, 40(06): 915-922) used the sol-gel process to prepare SiO2 ceramic coatings with single-layer and double-layer structures on the surface of 2024 aluminum alloy. The results showed that both coating structures had good hardness and adhesion on the surface of 2024 aluminum alloy, and the double-layer ceramic coating had better corrosion resistance on the aluminum alloy substrate than the single-layer. However, after the coating was mechanically damaged or environmentally eroded, the protective performance of the damaged area would be significantly reduced, resulting in rapid expansion of local corrosion, which in turn affected the durability and safety of the overall structure. At the same time, due to the complexity and time-consuming nature of the traditional repair process, the subsequent repair workload of the aluminum alloy anti-corrosion coating increased significantly, which not only increased the maintenance cost, but also may have an adverse effect on the normal operation and service life of the equipment.

[0007] The Chinese patent "An anti-corrosion coating for cast aluminum alloy and a method for preparing a surface composite film thereof" (application number: 201910499106.3, authorization number: CN110238345 A, announcement date: 2019.06.11) discloses an anti-corrosion coating for cast aluminum alloy and a method for preparing a surface composite film thereof. First, an inorganic nano-coating is applied to the surface of the casting cavity, and the smelted aluminum liquid is poured into the casting cavity. The coating dissolves and reacts with the aluminum liquid under the heat of the aluminum liquid, thereby forming a dense surface composite film composed of an oxide film and a salt film on the surface. This surface composite film has good superhydrophobicity and corrosion resistance. However, this surface composite film is prepared from a coating composed of a mixture of multiple inorganic nanoparticles. The agglomeration phenomenon of the nanoparticles is serious, which will damage the mechanical properties of the surface composite film. Moreover, the superhydrophobicity of the surface composite film is imparted by the mixed particles, and the performance is uneven. Summary of the Invention

[0008] The purpose of the present invention is to provide an intelligent response aluminum alloy anti-corrosion coating and its preparation method, which solves the problems in the prior art caused by environmental factors such as coating damage, dust ions and Cl - The problem of adhesion on the coating surface leads to a decrease in the corrosion resistance of the coating.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A method for preparing an intelligent responsive aluminum alloy anti-corrosion coating is specifically implemented according to the following steps:

[0011] Step 1: Preparation of MSNs

[0012] The template agent was dissolved in deionized water, and a strong base was added to adjust the pH of the mixed solution to 9-11. The mixed solution was then placed in a water bath and stirred for preheating. A silicon source was added and the mixture was stirred for sufficient reaction. The resulting white precipitate was centrifuged, repeatedly washed with anhydrous ethanol, and dried in a vacuum drying oven to obtain the MSNs precursor.

[0013] The MSNs precursor is added to a mixed solution of an organic solvent and hydrochloric acid, heated under reflux, and the product is filtered and repeatedly washed with anhydrous ethanol. The product is then placed in a vacuum drying oven for drying to obtain MSNs.

[0014] Step 2: Preparation of porous sea urchin-like MOFs / MSNs

[0015] Dissolving two different metal salts and organic ligand powders in an organic solvent to obtain a MOFs precursor solution; adding the MSNs obtained in step 1 to the MOFs precursor solution and stirring until the MSNs are uniformly dispersed in the MOFs precursor solution; pouring the mixed solution into a polytetrafluoroethylene-lined container and placing it in a hydrothermal drying oven for hydrothermal treatment; centrifuging the hydrothermal mixed solution to obtain a precipitate, repeatedly washing the precipitate with cyclohexane, and then freeze-drying the precipitate to obtain porous sea urchin-like MOFs / MSNs;

[0016] Step 3: Preparation of MOFs / MSNs loaded with corrosion inhibitors

[0017] The organic corrosion inhibitor is dissolved in an organic solvent to obtain a mixed solution; the MOFs / MSNs obtained in step 3 are added to the mixed solution, and the MOFs / MSNs are uniformly dispersed in the mixed solution by ultrasound, and then the mixed solution is stirred in a water bath until the organic corrosion inhibitor is fully loaded into the MOFs / MSNs; the mixed solution is centrifuged and repeatedly washed with anhydrous ethanol, and the final product is placed in a vacuum drying oven to obtain MOFs / MSNs loaded with the corrosion inhibitor;

[0018] Step 4: Preparation of aluminum alloy anti-corrosion coating

[0019] The PDMS main agent and the curing agent are mixed to obtain PDMS, and then an organic solvent is slowly added, and the mixture is placed on a magnetic stirrer for stirring to obtain a PDMS dilute solution; the MOFs / MSNs loaded with corrosion inhibitor obtained in step 4 are added to the PDMS dilute solution, stirred evenly to obtain a mixed solution, and the PDMS dilute solution is evenly coated on the aluminum alloy surface by spin coating, and the mixture is placed in a vacuum drying oven for drying to finally obtain an aluminum alloy anti-corrosion coating.

[0020] Furthermore, in step 1, the mass fraction of the template in deionized water is 0.1 wt.% to 0.5 wt.%, the mass fraction of the strong base in deionized water is 1 wt.% to 20 wt.%, the water bath temperature in the water bath is 30°C to 50°C, the water bath time is 60 min to 120 min, the molar ratio of the silicon source to the template is 5 to 15, the vacuum drying temperature is 50°C to 80°C, and the vacuum drying time is 2 h to 6 h;

[0021] The mass ratio of MSNs precursor to organic solvent is 1:20 to 1:100, the mass fraction of hydrochloric acid in deionized water is 20 wt.% to 50 wt.%, the volume ratio of organic solvent to hydrochloric acid is 50 to 200, the reflux temperature is 40°C to 70°C, the reflux time is 1h to 7h, the vacuum drying temperature is 50°C to 80°C, and the drying time is 2h to 6h.

[0022] Furthermore, in step 1, the template agent is any one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, dichloro-N,N'-bis(3-hydrogenated abietic acid-2-hydroxypropyl)tetramethylethylenediamine, and polystyrene; the strong base is any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide; the silicon source is any one of ethyl orthosilicate, methyl orthosilicate, methyltrimethoxysilane, and methyltriethoxysilane; and the organic solvent is any one of methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, acetone, and ethyl acetate.

[0023] Furthermore, in step 2, the molar ratio of the organic ligand to the two different metal salts is 0.5 to 2, the molar concentration of the two different metal salts in the organic solvent is 0.1 mol / L to 1 mol / L, the mass ratio of MSNs to the two different metal salts is 0.1 to 5, the hydrothermal temperature is 80°C to 160°C, the hydrothermal time is 4h to 24h, the freeze-drying temperature is -60°C to -40°C, and the freeze-drying time is 24h to 72h.

[0024] Furthermore, in step 2, the metal salt is any one of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, chromium nitrate nonahydrate, zinc nitrate hexahydrate, copper nitrate trihydrate, and nickel chloride hexahydrate, the organic ligand powder is any one of terephthalic acid, trimesic acid, phthalic acid, and 2-methylimidazole, the organic solvent is any one of anhydrous ethanol, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and N-methylpyrrolidone, and the molar ratio of the two different metal salts is 0.1 to 1.

[0025] Furthermore, in step 3, the mass fraction of the organic corrosion inhibitor in the organic solvent is 5wt.% to 20wt.%, the mass ratio of MOFs / MSNs to the organic corrosion inhibitor is 10:1 to 1:20, the water bath temperature is 30°C to 60°C, the water bath time is 4h to 10h, the drying temperature is 50°C to 80°C, and the drying time is 2h to 6h.

[0026] Furthermore, in step 3, the organic corrosion inhibitor is any one of benzotriazole, 2-mercaptobenzimidazole, 2-benzothiazole, 8-hydroxyquinoline, sodium dodecylbenzenesulfonate, and sodium dodecyl sulfate, and the organic solvent is any one of anhydrous ethanol, methanol, acetone, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide.

[0027] Furthermore, in step 4, the ratio of PDMS main agent to curing agent is 10:1, the mass fraction of PDMS in the organic solvent is 5wt.% to 40wt.%, the mass ratio of MOFs / MSNs to PDMS is 1:4 to 1:10, the drying temperature is 50°C to 80°C, and the drying time is 2h to 6h.

[0028] Furthermore, the organic solvent in step 4 is any one of cyclohexane, n-hexane, tetrahydrofuran, ethyl acetate, and acetone.

[0029] The aluminum alloy anti-corrosion coating is prepared according to the above-mentioned preparation method of the intelligent response aluminum alloy anti-corrosion coating.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention prepares an intelligent responsive aluminum alloy anti-corrosion coating, which can realize the intelligent corrosion inhibition function of self-sensing and self-releasing in the presence of corrosive media or mechanical damage, thereby significantly improving the long-term protection ability of the aluminum alloy substrate. - When in an environment with corrosive ions such as Cl - It will destroy the coordination balance of the active metals in bimetallic MOFs, induce the local collapse of their skeleton structure, and then release the embedded corrosion inhibitors. At the same time, the structural metals in MOFs maintain their structure without collapse, achieving the coordinated unity of structural protection and functional release under dynamic response. -It can also undergo ion exchange reactions with the organic ligands in MOFs, further driving the precise release of corrosion inhibitors, inhibiting anodic dissolution and cathodic reactions at the source, and blocking the electrochemical process of corrosion. When the coating is mechanically damaged, the corrosion inhibitors in the mesoporous structure of MSNs can also be quickly released, covering the exposed areas, filling the protection gaps, and achieving secondary protection for the aluminum alloy substrate. The structural and functional synergistic effect between bimetallic MOFs and MSNs gives the coating higher response sensitivity and corrosion inhibition efficiency in dynamic corrosion environments. The bimetallic porous sea urchin-like MOFs not only give the coating low surface energy, reducing the probability of Cl- and pollution particles adhering; at the same time, the unique sea urchin-like rough structure can also enhance the microstructure of the coating surface, improve antifouling performance and extend the protection life. Overall, the coating has broad practical application prospects and industrial value in many fields with high corrosion resistance requirements, such as aerospace, shipbuilding, consumer electronics, and daily appliances. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of a partial cross section of MOFs / MSNs loaded with corrosion inhibitor prepared by the present invention;

[0033] In the figure, 1-MSNs, 2-porous sea urchin-like MOFs, 3-organic corrosion inhibitor. DETAILED DESCRIPTION

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

[0035] A method for preparing an intelligent responsive aluminum alloy anti-corrosion coating is specifically implemented by the following steps:

[0036] Step 1: Preparation of MSNs

[0037] An appropriate amount of template agent was dissolved in deionized water, and a strong base was added to adjust the pH value of the mixed solution to 9-11. The mixed solution was then placed in a water bath at 30-50°C and stirred at a speed of 300-600 r / min for preheating for 60-120 min. A silicon source was added and the reaction was continued at a speed of 300-600 r / min for 1-4 h. The obtained white precipitate was centrifuged at 8000-10000 r / min for 2-10 min and washed repeatedly with anhydrous ethanol for 3-10 times. It was then placed in a vacuum drying oven at 50-80°C for 2-6 h to obtain an MSNs precursor. The template agent was hexadecyltrimethylammonium bromide (CTAB), ... Any one of methylammonium chloride (CTAC), dichloro-N,N'-bis(3-hydrogenated abietic acid 2-hydroxypropyl)tetramethylethylenediamine (DHRT), polystyrene (PS), etc., the strong base is any one of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), etc., the mass fraction of the template in deionized water is 0.1wt.% to 0.5wt.%, the mass fraction of the strong base in deionized water is 1wt.% to 20wt.%, the silicon source is any one of tetraethyl orthosilicate (TEOS), methyl orthosilicate (TMOS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), etc., and the molar ratio of the silicon source to the template is 5 to 15.

[0038] The MSNs precursor is added to a mixed solution of an organic solvent and hydrochloric acid (HCl), heated under reflux at 40°C to 70°C for 1h to 7h, the product is filtered, and the product is repeatedly washed with anhydrous ethanol for 3 to 10 times, and then the product is placed in a vacuum drying oven at 50°C to 80°C for 2h to 6h to obtain MSNs; wherein the organic solvent is any one of methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, acetone, ethyl acetate, etc., the mass ratio of the MSNs precursor to the organic solvent is 1:20 to 1:100, the mass fraction of hydrochloric acid in deionized water is 20wt.% to 50wt.%, and the volume ratio of the organic solvent to hydrochloric acid (HCl) is 50 to 200.

[0039] Step 2: Preparation of porous sea urchin-like MOFs / MSNs

[0040] Two different metal salts and organic ligand powders are dissolved in an organic solvent in a certain molar ratio to obtain a MOFs precursor solution; the MSNs in step 1 are added to the MOFs precursor solution and stirred at a speed of 300 r / min to 600 r / min for 20 min to 60 min until the MSNs are uniformly dispersed in the MOFs precursor solution; the mixed solution is poured into a polytetrafluoroethylene liner and placed in a hydrothermal drying oven at 80°C to 160°C for 4 h ~24h, then the hydrothermal mixed solution is centrifuged at a centrifugal speed of 8000r / min~10000r / min for 2min~10min, and then the precipitate is washed with cyclohexane 3~10 times, and then placed in a -60℃~-40℃ freeze dryer for freeze drying for 24h~72h to obtain MOFs / MSNs; wherein the metal salts are ferric nitrate nonahydrate (Fe(NO3)3·9H2O), cobalt nitrate hexahydrate (Co(NO3)2·6H2O), Chromium nitrate nonahydrate (Cr(NO3)3·9H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), copper nitrate trihydrate (Cu(NO3)2·3H2O), nickel chloride hexahydrate (NiCl2·6H2O), etc., the organic ligand powder is any one of terephthalic acid (BDC), trimesic acid (BTC), phthalic acid (DOP), 2-methylimidazole (2-MI), etc., the organic ligand is a mixture of two different metal salts. The molar ratio is 0.5-2, the organic solvent is any one or two of anhydrous ethanol, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), tetrahydrofuran (THF), N-methylpyrrolidone (NMP), etc., the molar concentration of the two different metal salts in the organic solvent is 0.1 mol / L-1 mol / L, the mass ratio of MSNs to the two different metal salts is 0.1-5, and the molar mass ratio of the two different metal salts is 0.1-1.

[0041] Step 3: Preparation of MOFs / MSNs loaded with corrosion inhibitors

[0042] The organic corrosion inhibitor is dissolved in an organic solvent to obtain a mixed solution; the MOFs / MSNs obtained in step 2 are added to the mixed solution, and ultrasonicated at a power of 200W to 400W for 15min to 40min to uniformly disperse the MOFs / MSNs in the mixed solution, and then the mixed solution is stirred at 300r / min to 600r / min in a water bath at 30℃ to 60℃ for 4h to 10h until the organic corrosion inhibitor is fully loaded into the MOFs / MSNs; the mixed solution is centrifuged at 8000r / min to 10000r / min for 2min to 10min, and then repeatedly washed with anhydrous ethanol for 3 to 10 times, and the final product is placed in a vacuum oven at 50℃ to 80℃. The mixture is dried in a drying oven for 2 hours to 6 hours to obtain MOFs / MSNs loaded with a corrosion inhibitor; wherein the organic corrosion inhibitor is any one of benzotriazole (BTA), 2-mercaptobenzimidazole (MBI), 2-benzothiazole (MBT), 8-hydroxyquinoline (HQ), sodium dodecylbenzenesulfonate (SDBS), sodium dodecyl sulfate (SDS), etc.; the organic solvent is any one of anhydrous ethanol, methanol, acetone, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc.; the mass fraction of the organic corrosion inhibitor in the organic solvent is 5wt% to 20wt%, and the mass ratio of MOFs / MSNs to the organic corrosion inhibitor is 10:1 to 1:20.

[0043] Step 4: Preparation of aluminum alloy anti-corrosion coating

[0044] The PDMS main agent and the curing agent are mixed in a ratio of 10:1 to obtain PDMS, and then an organic solvent is slowly added, and the mixture is placed on a magnetic stirrer and stirred at 300r / min~600r / min for 30min~120min to obtain a PDMS dilution solution; the MOFs / MSNs loaded with corrosion inhibitor in step 4 is added to the PDMS dilution solution, and stirred at 300r / min~600r / min for 30min~120min to obtain a mixed solution, and the mixed solution is evenly coated on the surface of the aluminum alloy by spin coating, and placed in a vacuum drying oven at 50℃~80℃ for 2h~6h to finally obtain an intelligent responsive aluminum alloy anti-corrosion coating; wherein the organic solvent is any one of cyclohexane, n-hexane, tetrahydrofuran (THF), ethyl acetate, acetone, etc., the mass fraction of PDMS in the organic solvent is 5wt.%~40wt.%, and the mass ratio of MOFs / MSNs loaded with corrosion inhibitor to PDMS is 1:4~1:10.

[0045] Figure 1 Schematic diagram of the partial cross section of MOFs / MSNs loaded with corrosion inhibitor prepared by the present invention. Figure 1It can be seen that sea urchin-like MOFs2 are in situ grown on the surface of MNSs1, and the organic corrosion inhibitor 3 is uniformly loaded in the mesopores of MNSs1 and the pores of sea urchin-like MOFs2.

[0046] Example 1 Preparation (Z N / N I -BDC) / MSN S @PDMS coating

[0047] 1.0 g of CTAB was dissolved in 1000 ml of deionized water, and 1 wt.% NaOH was added to adjust the pH of the mixed solution to 9. The mixed solution was then placed in a 30°C water bath and preheated at 300 r / min for 120 min. After 5.11 g of TEOS was added, the mixture was stirred at 300 r / min for 4 h. The resulting white precipitate was centrifuged at 8000 r / min for 2 min, washed repeatedly with anhydrous ethanol 10 times, and then dried in a 50°C vacuum drying oven for 6 h to obtain an MSNs precursor. 2.0 g of the MSNs precursor was added to a mixed solution of 51 ml of anhydrous ethanol and 1.02 ml of 20 wt.% HCl, heated under reflux at 40°C for 7 h, and the product was filtered and washed repeatedly with anhydrous ethanol 3 times. The product was then dried in a 50°C vacuum drying oven for 6 h to obtain MSNs.

[0048] 2.4 g Zn(NO3)2·6H2O, 2.0 g NiCl2·6H2O and 5.57 g BDC were dissolved in 161 ml anhydrous ethanol to obtain a Zn / Ni-BDC precursor solution; 2.53 g MSNs were added to the Zn / Ni-BDC precursor solution and stirred at 300 r / min for 60 min until the MSNs were uniformly dispersed in the Zn / Ni-BDC precursor solution; the mixed solution was poured into a polytetrafluoroethylene liner and placed in an 80°C hydrothermal drying oven for hydrothermal treatment for 24 h. The hydrothermal solution was then centrifuged at 8000 r / min for 2 min, and the precipitate was washed three times with cyclohexane. It was then placed in a -60°C freeze dryer and dried for 24 h to obtain (Zn / Ni-BDC) / MSNs;

[0049] 1.0 g of BTA was dissolved in 20 ml of anhydrous ethanol, and 10.0 g of (Zn / Ni-BDC) / MSNs was added to the mixed solution. The mixture was ultrasonicated at a power of 200 W for 40 min to uniformly disperse the (Zn / Ni-BDC) / MSNs in the solution. The mixed solution was then stirred at 300 r / min in a 30°C water bath for 4 h until BTA was fully loaded into the (Zn / Ni-BDC) / MSNs. The mixed solution was centrifuged at 8000 r / min for 2 min and washed repeatedly with anhydrous ethanol three times. The final product was placed in a 50°C vacuum drying oven and dried for 6 h to obtain BTA-loaded (Zn / Ni-BDC) / MSNs.

[0050] 5.0 g of PDMS main agent was mixed with 0.5 g of curing agent, and then 100 ml of cyclohexane was slowly added. The mixture was placed on a magnetic stirrer and stirred at 300 r / min for 120 min to obtain a PDMS dilute solution. 1.375 g of BTA-loaded (Zn / Ni-BDC) / MSNs in step 4 was added to the above-mentioned PDMS dilute solution, and stirred at 300 r / min for 30 min to obtain a mixed solution. The mixed solution was evenly coated on the aluminum alloy surface by spin coating, and placed in a 50°C vacuum drying oven and dried for 6 h to finally obtain an aluminum alloy anti-corrosion coating.

[0051] Example 2 Preparation (C O / Z N -BTC) / MSNS@PDMS coating

[0052] 1.5 g of CTAC was dissolved in 300 ml of deionized water, and 20 wt.% of Ca(OH)2 was added to adjust the pH of the mixed solution to 11. The mixed solution was then placed in a 50°C water bath and preheated at 600 r / min for 60 min. After 10.7 g of TMOS was added, the mixture was stirred at 600 r / min for 1 h. The resulting white precipitate was centrifuged at 10,000 r / min for 10 min, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 80°C for 2 h to obtain an MSNs precursor. 4.0 g of the MSNs precursor was added to a mixed solution of 300 ml of ethylene glycol and 1.5 ml of 50 wt.% HCl, heated under reflux at 70°C for 1 h, filtered, and washed 10 times with anhydrous ethanol. The product was then dried in a vacuum drying oven at 80°C for 2 h to obtain MSNs.

[0053] 1.01 g Co(NO3)2·6H2O, 10.0 g Zn(NO3)2·6H2O and 16.0 g BTC were dissolved in 38.2 ml DMF to obtain a Co / Zn-BTC precursor solution; 11.01 g MSNs were added to the Co / Zn-BTC precursor solution and stirred at 600 r / min for 20 min until the MSNs were uniformly dispersed in the Co / Zn-BTC precursor solution; the mixed solution was poured into a polytetrafluoroethylene liner and placed in a 160°C hydrothermal drying oven for hydrothermal heating for 4 h, and then the hydrothermal solution was centrifuged at 10,000 r / min for 10 min, and the precipitate was washed 10 times with cyclohexane, and then placed in a -40°C freeze dryer for drying for 72 h to obtain (Co / Zn-BTC) / MSNs;

[0054] 2.0 g of MBI was dissolved in 10 ml of DMSO, and 0.1 g of (Co / Zn-BTC) / MSNs was added to the mixed solution. The solution was ultrasonicated at a power of 400 W for 15 min to uniformly disperse the (Co / Zn-BTC) / MSNs in the solution. The mixed solution was then stirred at 600 r / min in a 60°C water bath for 10 h until MBI was fully loaded into the (Co / Zn-BTC) / MSNs. The mixed solution was centrifuged at 10,000 r / min for 10 min and washed repeatedly with anhydrous ethanol 10 times. The final product was placed in a vacuum drying oven at 80°C for 2 h to obtain MBI-loaded (Co / Zn-BTC) / MSNs.

[0055] 10.0 g of PDMS main agent and 1.0 g of curing agent were mixed, and then 27.5 ml of cyclohexane was slowly added. The mixture was placed on a magnetic stirrer and stirred at 600 r / min for 30 min to obtain a PDMS dilute solution. 2.5 g of MBI-loaded (Co / Zn-BTC) / MSNs in step 4 was added to the above-mentioned PDMS dilute solution, and stirred at 600 r / min for 120 min to obtain a mixed solution. The mixed solution was evenly coated on the aluminum alloy surface by spin coating, and placed in an 80°C vacuum drying oven for 2 h to finally obtain an aluminum alloy anti-corrosion coating.

[0056] Example 3 Preparation (C U / C R -DOP) / MSNS@PDMS coating

[0057] 0.12 g of DHRT was dissolved in 24 ml of deionized water, and 10 wt.% KOH was added to adjust the pH of the mixed solution to 10. The mixed solution was then placed in a 40°C water bath and preheated at 500 r / min for 90 min. After adding 2.1 g of MTMS, the mixture was stirred at 500 r / min for 3 h. The resulting white precipitate was centrifuged at 9000 r / min for 5 min, washed repeatedly with anhydrous ethanol five times, and then dried in a vacuum drying oven at 60°C for 4 h to obtain an MSNs precursor. 2.0 g of the MSNs precursor was added to a mixed solution of 111 ml of ethyl acetate and 1.1 ml of 30 wt.% HCl, heated under reflux at 60°C for 5 h, and the product was filtered and washed repeatedly with anhydrous ethanol five times. The product was then dried in a vacuum drying oven at 60°C for 4 h to obtain MSNs.

[0058] 2.43 g of Cu(NO3)2·3H2O, 8.0 g of Cr(NO3)3·9H2O and 7.8 g of DOP were dissolved in 40 ml of NMP to obtain a Cu / Cr-DOP precursor solution; 15.4 g of MSNs were added to the Cu / Cr-DOP precursor solution and stirred at 500 r / min for 40 min until the MSNs were uniformly dispersed in the Cu / Cr-DOP precursor solution; the mixed solution was poured into a polytetrafluoroethylene liner and placed in a 120°C hydrothermal drying oven for hydrothermal heating for 16 h, and then the hydrothermal solution was centrifuged at 9000 r / min for 5 min, and the precipitate was washed with cyclohexane 5 times, and then placed in a -50°C freeze dryer for drying for 48 h to obtain (Cu / Cr-DOP) / MSNs;

[0059] 1.5 g of MBT was dissolved in 15 ml of THF, and 1.5 g of (Cu / Cr-DOP) / MSNs was added to the mixed solution. The solution was ultrasonicated at a power of 300 W for 30 min to uniformly disperse the (Cu / Cr-DOP) / MSNs in the solution. The mixed solution was then stirred at 500 r / min in a 40°C water bath for 6 h until MBT was fully loaded into the (Cu / Cr-DOP) / MSNs. The mixed solution was centrifuged at 9000 r / min for 5 min and washed repeatedly with anhydrous ethanol five times. The final product was placed in a vacuum drying oven at 60°C and dried for 4 h to obtain MBT-loaded (Cu / Cr-DOP) / MSNs.

[0060] 6.0 g of PDMS main agent was mixed with 0.6 g of curing agent, and then 23.4 ml of n-hexane was slowly added. The mixture was placed on a magnetic stirrer and stirred at 600 r / min for 30 min to obtain a PDMS dilute solution. 1.5 g of MBI-loaded (Cu / Cr-DOP) / MSNs in step 4 was added to the above-mentioned PDMS dilute solution, and stirred at 500 r / min for 90 min to obtain a mixed solution. The mixed solution was evenly coated on the aluminum alloy surface by spin coating, and placed in a vacuum drying oven at 60°C for 4 h to finally obtain an aluminum alloy anti-corrosion coating.

[0061] Example 4 Preparation (N I / C U -BTC) / MSNS@PDMS coating

[0062] 2.0 g of CTAC was dissolved in 500 ml of deionized water, and 10 wt.% NaOH was added to adjust the pH of the mixed solution to 9.6. The mixed solution was then placed in a 40°C water bath and preheated at 600 r / min for 100 min. After 16.7 g of MTES was added, the mixture was stirred at 500 r / min for 2 h. The resulting white precipitate was centrifuged at 8000 r / min for 3 min, washed four times with anhydrous ethanol, and dried in a vacuum drying oven at 70°C for 5 h to obtain the MSNs precursor. 2.5 g of the MSNs precursor was added to a mixed solution of 318 ml of acetone and 2.12 ml of 30 wt.% HCl, heated under reflux at 50°C for 6 h, and the product was filtered and washed five times with anhydrous ethanol. The product was then dried in a vacuum drying oven at 70°C for 5 h to obtain the MSNs.

[0063] 5.9 g NiCl2·6H2O, 6.0 g Cu(NO3)2·3H2O and 11.1 g BTC were dissolved in 50 ml DMF to obtain a Ni / Cu-BTC precursor solution; 25.2 g MSNs were added to the Ni / Cu-BTC precursor solution and stirred at 400 r / min for 40 min until the MSNs were uniformly dispersed in the Ni / Cu-BTC precursor solution; the mixed solution was poured into a polytetrafluoroethylene liner and placed in a 120°C hydrothermal drying oven for hydrothermal heating for 16 h, and then the hydrothermal solution was centrifuged at 8000 r / min for 3 min, and the precipitate was washed with cyclohexane 4 times, and then placed in a -60°C freeze dryer for drying for 36 h to obtain (Ni / Cu-BTC) / MSNs;

[0064] 2.5 g of SDS was dissolved in 12.5 ml of acetone, and 25 g of (Ni / Cu-BTC) / MSNs was added to the mixed solution. The solution was ultrasonicated at a power of 350 W for 35 min to uniformly disperse the (Ni / Cu-BTC) / MSNs in the solution. The mixed solution was then stirred at 400 r / min in a 40°C water bath for 5 h until SDS was fully loaded into the (Ni / Cu-BTC) / MSNs. The mixed solution was centrifuged at 8000 r / min for 3 min and washed four times with anhydrous ethanol. The final product was placed in a vacuum drying oven at 70°C and dried for 4 h to obtain SDS-loaded (Ni / Cu-BTC) / MSNs.

[0065] 8.0 g of PDMS main agent and 0.8 g of curing agent were mixed, and then 22 ml of ethyl acetate was slowly added. The mixture was placed on a magnetic stirrer and stirred at 400 r / min for 90 min to obtain a PDMS dilute solution. 0.88 g of SDS-loaded (Ni / Cu-BTC) / MSNs in step 4 was added to the above-mentioned PDMS dilute solution, and stirred at 400 r / min for 80 min to obtain a mixed solution. The mixed solution was evenly coated on the aluminum alloy surface by spin coating, and placed in a vacuum drying oven at 70°C for 3 h to finally obtain an aluminum alloy anti-corrosion coating.

[0066] Comparative Example Preparation of MSNS@PDMS Coating

[0067] 1.5 g of CTAB was dissolved in 500 ml of deionized water, and 12 wt.% NaOH was added to adjust the pH of the mixed solution to 9.6. The mixed solution was then placed in a 40°C water bath and preheated at 600 r / min for 100 min. After 8.57 g of TEOS was added, the mixture was stirred at 500 r / min for 2 h. The resulting white precipitate was centrifuged at 8000 r / min for 3 min, washed four times with anhydrous ethanol, and dried in a vacuum drying oven at 70°C for 5 h to obtain an MSNs precursor. 3 g of the MSNs precursor was added to a mixed solution of 158 ml of acetone and 1.1 ml of 35 wt.% HCl, heated under reflux at 50°C for 6 h, and the product was filtered and washed five times with anhydrous ethanol. The product was then dried in a vacuum drying oven at 70°C for 5 h to obtain MSNs.

[0068] 2.5 g of SDS was dissolved in 25 ml of acetone, and 37.5 g of MSNs were added to the mixed solution. The mixture was ultrasonicated at a power of 350 W for 35 min to uniformly disperse the MSNs in the solution. The mixed solution was then stirred at 400 rpm in a 40°C water bath for 5 h until the SDS was fully loaded into the MSNs. The mixed solution was centrifuged at 8000 rpm for 3 min and washed four times with anhydrous ethanol. The final product was dried in a vacuum drying oven at 70°C for 4 h to obtain SDS-loaded MSNs.

[0069] 12.0 g of PDMS main agent and 1.2 g of curing agent were mixed, and then 44 ml of ethyl acetate was slowly added. The mixture was placed on a magnetic stirrer and stirred at 400 r / min for 90 min to obtain a PDMS dilute solution. 1.32 g of SDS-loaded MSNs in step 4 was added to the above-mentioned PDMS dilute solution, and stirred at 400 r / min for 80 min to obtain a mixed solution. The mixed solution was evenly coated on the aluminum alloy surface by spin coating, and placed in a vacuum drying oven at 70°C for 3 h to finally obtain an aluminum alloy anti-corrosion coating.

[0070] The difference between the comparative example and Examples 1-4 is that the urchin-like bimetallic MOF particles were not in situ synthesized on the MSNs surface, and the organic corrosion inhibitor was only loaded in the MSNs mesopores. - Intelligent response.

[0071] Table 1 is the anti-corrosion performance and hydrophobicity comparison of the intelligent response aluminum alloy anti-corrosion coating prepared by Example 1-4 and Comparative Example.As can be seen from Table 1, the contact angle (WCAs) of Comparative Example is 120 °, and the rolling angle (WSAs) is 10.5 °, and its hydrophobicity does not reach super-hydrophobic standard (WCAs>150 °).And in Example 1-4, due to the growth of sea urchin-shaped MOFs material on the MSNs surface, the roughness of the coating surface is significantly increased, so that WCAs is greater than 150 °, indicating that the modified aluminum alloy anti-corrosion coating has reached super-hydrophobic state.In addition, as can be seen from the resistance modulus value, MOFs and MSNs are both loaded with corrosion inhibitor, and corrosion inhibition efficiency is significantly improved. The resistance modulus value of the modified anti-corrosion coating is improved by about 4 orders of magnitude before modification, proving that its corrosion resistance is significantly enhanced.After 100 wear cycles are tested by sandpaper to anti-corrosion coating, it is found that the contact angle of coating decreases very little, still maintains excellent super-hydrophobic performance. This is attributed to the fact that the MOFs material generated in situ on the surface of MSNs enhances the bonding force between MSNs and PDMS, thereby significantly improving the wear resistance of the coating.

[0072] Table 1 Hydrophobicity and anti-corrosion performance of the intelligent response anti-corrosion coating in Examples 1-4

[0073]

[0074] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for preparing an intelligent response aluminum alloy anti-corrosion coating, characterized in that: Please follow the steps below to implement: Step 1: Preparation of MSNs The template agent was dissolved in deionized water, and a strong base was added to adjust the pH of the mixed solution to 9-11. The mixed solution was then placed in a water bath and stirred for preheating. A silicon source was added and the mixture was stirred for sufficient reaction. The resulting white precipitate was centrifuged, repeatedly washed with anhydrous ethanol, and dried in a vacuum drying oven to obtain the MSNs precursor. The MSNs precursor is added to a mixed solution of an organic solvent and hydrochloric acid, heated under reflux, and the product is filtered and repeatedly washed with anhydrous ethanol. The product is then placed in a vacuum drying oven for drying to obtain MSNs. Step 2: Preparation of porous sea urchin-like MOFs / MSNs Dissolving two different metal salts and organic ligand powder in an organic solvent to obtain a MOFs precursor solution; adding the MSNs obtained in step 1 to the MOFs precursor solution and stirring until the MSNs are uniformly dispersed in the MOFs precursor solution; The mixed solution was poured into a polytetrafluoroethylene-lined container and placed in a hydrothermal drying oven for hydrothermal heating. The hydrothermal mixed solution was centrifuged to obtain a precipitate, which was repeatedly washed with cyclohexane and then freeze-dried to obtain porous sea urchin-like MOFs / MSNs. Step 3: Preparation of MOFs / MSNs loaded with corrosion inhibitors The organic corrosion inhibitor is dissolved in an organic solvent to obtain a mixed solution; the MOFs / MSNs obtained in step 3 are added to the mixed solution, and the MOFs / MSNs are uniformly dispersed in the mixed solution by ultrasound, and then the mixed solution is stirred in a water bath until the organic corrosion inhibitor is fully loaded into the MOFs / MSNs; the mixed solution is centrifuged and repeatedly washed with anhydrous ethanol, and the final product is placed in a vacuum drying oven to obtain MOFs / MSNs loaded with the corrosion inhibitor; Step 4: Preparation of aluminum alloy anti-corrosion coating The PDMS main agent and the curing agent are mixed to obtain PDMS, and then an organic solvent is slowly added, and the mixture is placed on a magnetic stirrer for stirring to obtain a PDMS dilution solution; the MOFs / MSNs loaded with corrosion inhibitor obtained in step 4 are added to the PDMS dilution solution, stirred evenly to obtain a mixed solution, and the mixed solution is evenly coated on the surface of the aluminum alloy by spin coating, and placed in a vacuum drying oven for drying to finally obtain an aluminum alloy anti-corrosion coating.

2. The method for preparing a smart response aluminum alloy anti-corrosion coating according to claim 1, characterized in that: In step 1, the mass fraction of the template in deionized water is 0.1 wt.% to 0.5 wt.%, the mass fraction of the strong base in deionized water is 1 wt.% to 20 wt.%, the water bath temperature in the water bath is 30°C to 50°C, the water bath time is 60 min to 120 min, the molar ratio of the silicon source to the template is 5 to 15, the vacuum drying temperature is 50°C to 80°C, and the vacuum drying time is 2 h to 6 h; The mass ratio of MSNs precursor to organic solvent is 1:20 to 1:100, the mass fraction of hydrochloric acid in deionized water is 20 wt.% to 50 wt.%, the volume ratio of organic solvent to hydrochloric acid is 50 to 200, the reflux temperature is 40°C to 70°C, the reflux time is 1h to 7h, the vacuum drying temperature is 50°C to 80°C, and the drying time is 2h to 6h.

3. The method for preparing a smart response aluminum alloy anti-corrosion coating according to claim 2, characterized in that: In step 1, the template agent is any one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, dichloro-N,N'-bis(3-hydrogenated abietic acid-2-hydroxypropyl)tetramethylethylenediamine, and polystyrene; the strong base is any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide; the silicon source is any one of ethyl orthosilicate, methyl orthosilicate, methyltrimethoxysilane, and methyltriethoxysilane; and the organic solvent is any one of methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, acetone, and ethyl acetate.

4. The method for preparing a smart response aluminum alloy anti-corrosion coating according to claim 1, characterized in that: In step 2, the molar ratio of the organic ligand to the two different metal salts is 0.5 to 2, the molar concentration of the two different metal salts in the organic solvent is 0.1 mol / L to 1 mol / L, the mass ratio of MSNs to the two different metal salts is 0.1 to 5, the hydrothermal temperature is 80°C to 160°C, the hydrothermal time is 4h to 24h, the freeze-drying temperature is -60°C to -40°C, and the freeze-drying time is 24h to 72h.

5. The method for preparing a smart response aluminum alloy anti-corrosion coating according to claim 4, characterized in that: In step 2, the metal salt is any one of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, chromium nitrate nonahydrate, zinc nitrate hexahydrate, copper nitrate trihydrate, and nickel chloride hexahydrate, the organic ligand powder is any one of terephthalic acid, trimesic acid, phthalic acid, and 2-methylimidazole, and the organic solvent is any one of anhydrous ethanol, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and N-methylpyrrolidone, and the molar ratio of the two different metal salts is 0.1 to 1.

6. The method for preparing a smart response aluminum alloy anti-corrosion coating according to claim 1, characterized in that: In step 3, the mass fraction of the organic corrosion inhibitor in the organic solvent is 5wt.% to 20wt.%, the mass ratio of MOFs / MSNs to the organic corrosion inhibitor is 10:1 to 1:20, the water bath temperature is 30°C to 60°C, the water bath time is 4h to 10h, the drying temperature is 50°C to 80°C, and the drying time is 2h to 6h.

7. The method for preparing a smart responsive aluminum alloy anti-corrosion coating according to claim 6, characterized in that: In step 3, the organic corrosion inhibitor is any one of benzotriazole, 2-mercaptobenzimidazole, 2-benzothiazole, 8-hydroxyquinoline, sodium dodecylbenzenesulfonate, and sodium dodecyl sulfate, and the organic solvent is any one of anhydrous ethanol, methanol, acetone, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide.

8. The method for preparing a smart response aluminum alloy anti-corrosion coating according to claim 1, characterized in that: In step 4, the ratio of PDMS main agent to curing agent is 10:1, the mass fraction of PDMS in the organic solvent is 5wt.% to 40wt.%, the mass ratio of MOFs / MSNs to PDMS is 1:4 to 1:10, the drying temperature is 50°C to 80°C, and the drying time is 2h to 6h.

9. The method for preparing a smart responsive aluminum alloy anti-corrosion coating according to claim 8, characterized in that: The organic solvent in step 4 is any one of cyclohexane, n-hexane, tetrahydrofuran, ethyl acetate, and acetone.

10. An aluminum alloy anti-corrosion coating prepared according to the method for preparing an intelligent responsive aluminum alloy anti-corrosion coating according to any one of claims 1 to 9.

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