Composite protective film with corrosion early warning function and preparation method thereof

Abstract

The application belongs to the field of corrosion and protection, and particularly relates to a composite protective film with corrosion early warning function and a preparation method thereof. The preparation method of the composite protective film with corrosion early warning function comprises the following steps: arranging a composite film layer based on metal oxide on the surface of a substrate, then arranging a metal organic framework material film layer on the surface of the composite film layer based on metal oxide, loading corrosion inhibitor in the metal organic framework material film layer, and finally arranging an organic silicon gel film layer on the surface of the metal organic framework material film layer. The preparation method of the protective film layer is simple, improves the protection performance of the protective film layer, and solves the problems of poor adhesion and easy falling of the metal organic framework material film layer. In addition, the different film layers of the protective film layer have different fluorescence phenomena, can realize intuitive observation of the damage condition of the film layer under ultraviolet light, and has a self-warning function before the substrate is corroded.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of corrosion and protection, and particularly relates to a composite protective film with corrosion early warning function and a preparation method thereof. BACKGROUND

[0002] Building protective coating is a common means in the field of metal corrosion protection. At present, the protective effect of the coating is mainly based on the shielding performance of the coating, and the coating isolates the corrosion medium from the metal, thereby destroying the necessary conditions for corrosion to occur. However, the traditional coating faces many problems in the process of use, such as the inability to intuitively evaluate the service condition of the coating, the complete failure of the protective effect caused by local damage of the coating, and the additional cost problems of manpower and material resources brought by maintenance.

[0003] Adding corrosion inhibitors to organic resin coatings is an effective means to increase the corrosion resistance of the coating, but the traditional adding method, such as directly adding corrosion inhibitors into the coating, has the problems of short action time of corrosion inhibitors and inability to be used for a long time. Therefore, it is often selected to add nano containers coated with corrosion inhibitors to realize the long-term release of corrosion inhibitors.

[0004] In addition, the doping of corrosion inhibitors in the coating will face the following problems, such as poor dispersion stability, uneven distribution, poor compatibility with the coating, and the like, which makes it difficult for the nano containers coated with corrosion inhibitors to produce corrosion protection effect in the coating. In order to solve this problem, thinning the intelligent nano container film and using its spatial structure to build a continuous protective film layer is an effective solution. This will make the coating make the most of the loading characteristics of the nano container material for corrosion inhibitors, and also provide physical shielding effect for the substrate. Metal organic framework materials (MOFs) have high permanent porosity and multifunctional adjustable structure, and can controllably form a continuous protective film layer with corrosion inhibitor loading function, and have become a research hotspot at present, but the preparation and use of such thin films still need to solve the problems of poor interfacial bonding force and easy falling off. Under this background, it has great practical value to design and develop a protective film layer with strong interfacial bonding force and excellent corrosion inhibitor loading and physical barrier performance. SUMMARY

[0005] Based on the above technical background, the main purpose of the present application is to provide a composite protective film with corrosion early warning function and a preparation method thereof, so as to overcome the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned purpose of the application, the technical scheme adopted by the present application comprises:

[0007] The first aspect of the present application is to provide a composite protective film with corrosion early warning function, which comprises, in order from bottom to top, a composite film layer based on metal oxide, a metal organic framework material film layer and an organic silicone gel film layer according to the coating order of the protective film, wherein,

[0008] The preparation raw materials of the metal oxide-based composite film layer include zinc salt, ethylene glycol methyl ether, ethanolamine and hexamethylenetetramine;

[0009] The metal organic framework material film layer is loaded with corrosion inhibitor, and the preparation raw materials of the metal organic framework material film layer include organic ligand of metal organic framework, corrosion inhibitor and sodium formate;

[0010] The preparation raw materials of the organosilica gel film layer include solution 1 and solution 2, the solution 1 is prepared from water, ethanol and organosilane, and the solution 2 is prepared from ethanol, ethyl acetoacetate and tetraethyl silicate.

[0011] Preferably, the zinc salt is selected from one or more of zinc acetate, zinc sulfate, zinc nitrate, zinc chloride, zinc bromide and zinc iodide; and / or,

[0012] The organic ligand of the metal organic framework is selected from one or more of 2,5-furandicarboxylic acid, terephthalic acid, 1,3,5-benzenetricarboxylic acid and 2-methylimidazole; and / or

[0013] The corrosion inhibitor is selected from one or more of 8-hydroxyquinoline, benzotriazole, 2-mercaptobenzothiazole and coumarin; and / or,

[0014] The organosilane is selected from one or more of aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane and vinyltriethoxysilane.

[0015] Preferably, the mass ratio of the zinc salt, ethylene glycol methyl ether and ethanolamine is 1:(4-15):(0.2-0.7); and / or,

[0016] The mass ratio of the zinc salt and hexamethylenetetramine is 1:(0.4-0.7); and / or,

[0017] The mass ratio of the organic ligand of the metal organic framework, the corrosion inhibitor and sodium formate is (10-65):1:(2-30); and / or,

[0018] The volume ratio of solution 1 and solution 2 is (1-3):1; and / or,

[0019] The volume ratio of the water, ethanol and organosilane is 1:(1-4):(1-4); and / or,

[0020] The volume ratio of the ethanol, ethyl acetoacetate and tetraethyl silicate is (1-5):1:(1-4).

[0021] The second aspect of the present application is to provide a preparation method of a composite protective film with corrosion warning effect, the preparation method comprising the following steps:

[0022] Step 1, zinc salt, ethylene glycol methyl ether and ethanolamine are added into water, stirred uniformly, and then aged to obtain a zinc oxide sol;

[0023] Step 2, the zinc oxide sol is dip-coated onto the surface of the substrate, and then heat treated to obtain a sample with a zinc oxide coating;

[0024] Step 3, zinc salt and hexamethylenetetramine are added into water and stirred uniformly to obtain a nanorod growth solution, and the sample with the zinc oxide coating is placed in the nanorod growth solution to obtain a sample with a zinc oxide nanorod array film layer;

[0025] Step 4, the organic ligand of the metal organic framework, the corrosion inhibitor and sodium formate are added into water and stirred uniformly to obtain a metal organic framework growth solution, and the sample with the zinc oxide nanorod array film layer is placed in the metal organic framework growth solution to obtain a sample loaded with the metal organic framework;

[0026] Step 5, water, ethanol and organosilane are mixed uniformly to obtain solution 1, ethanol, ethyl acetoacetate and tetraethyl orthosilicate are stirred uniformly, and then pH is adjusted to obtain solution 2, solution 2 is added into solution 1 and stirred, and then aged to obtain a silane sol;

[0027] Step 6, the silane sol is sprayed on the sample loaded with the metal organic framework, and then dried to obtain a composite protective film with corrosion warning effect.

[0028] Preferably, the zinc salt and the ethylene glycol methyl ether are stirred in water until the solution is clear, then the ethanolamine is added, and the reaction is carried out at a stirring speed of 400-800 rpm and at 50-80℃ for 10-60 min, and then aged for 20-30 h.

[0029] Preferably, in step 2, the dip-coating of the zinc oxide sol onto the surface of the substrate is carried out by using the dip-coating and pulling method, and the dip-coating and pulling rate is 40-90 mm / min; and / or,

[0030] The dip-coating and pulling is carried out twice, and the dip-coating time of each time is 3-8 min; and / or,

[0031] After the first dip-coating and pulling, the drying is carried out at 40-70℃ for 45-75 min; and / or,

[0032] After the second dip-coating and pulling, the heat treatment is carried out, and the heat treatment is carried out in a gradient heating mode, and the temperature is raised to 200-600℃ at a heating rate of 0.5℃ / min-2.5℃ / min, and then the temperature is kept at the highest temperature for 100-300 min.

[0033] Preferably, in step 3, the sample with the zinc oxide coating is placed in the nanorod growth solution and heated to 80-200℃ for 4-7h.

[0034] Preferably, in step 4, the sample with the zinc oxide nanorod array film layer is placed in the metal organic framework growth solution and heated to 50-100℃ for 3-40min.

[0035] Preferably, in step 5, the water, ethanol and organosilane are mixed and stirred at 300-700rpm for 10-60min; and / or,

[0036] The ethanol, ethyl acetoacetate and tetraethyl orthosilicate are stirred at 300-700rpm for 1h; and / or,

[0037] Solution 2 is added to solution 1 and stirred at 500-900rpm for 24h.

[0038] Preferably, in step 6, the spraying pressure of the silane sol is 3-10kPa; and / or,

[0039] The drying temperature is 60-120℃.

[0040] The second aspect of the present application provides a protective film layer with corrosion warning effect prepared by the preparation method of the composite protective film with corrosion warning effect according to the first aspect of the present application.

[0041] The present application has the following beneficial effects:

[0042] (1) The composite film layer based on metal oxides, the metal organic framework material film layer, the corrosion inhibitor and the organosilica gel film layer in the protective film layer with corrosion warning effect prepared by the present application have a synergistic corrosion inhibition effect. The organosilica gel film layer and the metal organic framework material film layer can physically block the corrosion medium. The corrosion inhibitor loaded in the metal organic framework material film layer and the composite film layer based on metal oxides can chemically act on the area of the film layer that is corroded, thereby achieving the anticorrosion effect. In addition, the organosilica gel film layer sprayed on the surface of the metal organic framework material film layer can seal the surface defects of the metal organic framework film layer, thereby solving the problems of poor adhesion and easy peeling of the metal organic framework film layer.

[0043] (2) The protective film layer with corrosion warning effect prepared by the present application utilizes the scattering of ultraviolet light by organosilica gel and the photoluminescence performance of zinc oxide to achieve the effect of layered warning without adding other fluorescent substances. The protective film layer can be directly observed under ultraviolet light before the substrate is corroded, and since no fluorescent substances are added, it is more environmentally friendly.

[0044] (3) The protective film layer prepared by the method has a thin thickness, and the adverse effects caused by the over-thick film layer are reduced, such as film thickness leading to sagging, cracking, delamination, wrinkling, increased drying time, improper curing and the like in the processing process.

[0045] (4) The preparation method of the protective film layer is simple, the preparation conditions are mild, and the cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 A flowchart showing the preparation method of the composite protective film with corrosion warning effect is shown.

[0047] Figure 2 A scanning electron microscope-energy spectrum (SEM-EDS) test diagram of the cross section of the composite protective film with corrosion warning effect prepared in Example 1 of the present application is shown.

[0048] Figure 3 A fluorescence test photo of the protective film layer prepared in Example 1 of the present application is shown.

[0049] wherein, Figure 3 Figure (a) in the figure is a fluorescence photo of the composite protective film with corrosion warning effect before corrosion;

[0050] Figure 3 Figure (b) in the figure is a fluorescence photo of the composite protective film with corrosion warning effect after preliminary corrosion;

[0051] Figure 3 Figure (c) in the figure is a fluorescence photo of the composite protective film with corrosion warning effect after further corrosion;

[0052] Figure 3 Figure (d) in the figure is a fluorescence photo of the composite protective film with corrosion warning effect after further corrosion;

[0053] Figure 3 Figure (e) in the figure is a fluorescence photo of the composite protective film with corrosion warning effect after complete corrosion.

[0054] Figure 4 A fluorescence photo of the protective film layer prepared in Example 1, Comparative Examples 1-3 is shown.

[0055] wherein, Figure 4 Figure (a) in the figure is a fluorescence photo of the ZnO NP prepared in Comparative Example 1;

[0056] Figure 4 Figure (b) in the figure is a fluorescence photo of the ZnO NR prepared in Comparative Example 2;

[0057] Figure 4Fig. 2 is a fluorescence photo of ZnO / ZIF-8@MBT prepared from Comparative Example 3;

[0058] Figure 4 Fig. 4 is a fluorescence photo of ZnO / ZIF8@MBT / SG prepared from Example 1.

[0059] Figure 5 Fig. 5 shows electrochemical test diagrams of the protective film layers prepared from Example 1, Comparative Examples 1-3:

[0060] Figure 5 Fig. 1 is a Nyquist diagram;

[0061] Figure 5 Fig. 2 is an impedance diagram;

[0062] Fig. 3 is a phase angle diagram corresponding to Fig. 2. DETAILED DESCRIPTION

[0063] The present application will be described in detail below, and the features and advantages of the present application will become more apparent with these descriptions.

[0064] The first aspect of the present application is to provide a composite protective film with corrosion warning effect, which comprises, from bottom to top, a composite film layer based on metal oxide, a metal organic framework material film layer and an organic silicone gel film layer in order of coating of the protective film, wherein,

[0065] The preparation raw materials of the composite film layer based on metal oxide include zinc salt, ethylene glycol methyl ether, ethanolamine and hexamethylenetetramine;

[0066] The metal organic framework material film layer is loaded with corrosion inhibitor, and the preparation raw materials of the metal organic framework material film layer include organic ligand of metal organic framework, corrosion inhibitor and sodium formate;

[0067] The preparation raw materials of the organic silicone gel film layer include solution 1 and solution 2, solution 1 is prepared from water, ethanol and organic silane, and solution 2 is prepared from ethanol, ethyl acetoacetate and tetraethyl silicate.

[0068] The zinc salt is selected from one or more of zinc acetate, zinc sulfate, zinc nitrate, zinc chloride, zinc bromide and zinc iodide, preferably zinc acetate, zinc nitrate, zinc chloride, zinc sulfate or zinc bromide.

[0069] The mass ratio of the zinc salt, ethylene glycol methyl ether and ethanolamine is 1:(4-15):(0.2-0.7), preferably the mass ratio of the zinc salt, ethylene glycol methyl ether and ethanolamine is 1:(5-12):(0.3-0.6).

[0070] The mass ratio of the zinc salt and hexamethylenetetramine is 1:(0.4-0.7), preferably the mass ratio is 1:(0.5-0.6).

[0071] The organic ligand of the metal organic framework is selected from one or more of 2,5-furan dicarboxylic acid, terephthalic acid, 1,3,5-benzenetricarboxylic acid and 2-methyl imidazole, preferably 2,5-furan dicarboxylic acid, terephthalic acid or 2-methyl imidazole.

[0072] The corrosion inhibitor is selected from one or more of 8-hydroxyquinoline, benzotriazole, 2-mercaptobenzothiazole and coumarin, preferably 8-hydroxyquinoline, benzotriazole or 2-mercaptobenzothiazole.

[0073] The mass ratio of the organic ligand of the metal organic framework, the corrosion inhibitor and sodium formate is (10-65):1:(2-30), preferably the mass ratio is (13-59):1:(3-25).

[0074] The organosilane is selected from one or more of aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane and vinyltriethoxysilane, preferably one or more of aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane and methacryloyloxypropyltrimethoxysilane.

[0075] The volume ratio of the water, the ethanol and the organosilane is 1:(1-4):(1-4), preferably the volume ratio is 1:(1-3):(1-3).

[0076] The volume ratio of the ethanol, ethyl acetoacetate and tetraethyl orthosilicate is (1-5):1:(1-4), preferably the volume ratio is (2-4):1:(2-3.5).

[0077] The volume ratio of solution 1 and solution 2 is (1-3):1, preferably the volume ratio is (1.5-2.6):1.

[0078] The second aspect of the present application is to provide a preparation method of a composite protective film with corrosion warning effect, the preparation method comprises the following steps, as shown in Figure 1

[0079] Step 1, zinc salt, ethylene glycol methyl ether and ethanolamine are added into water, stirred uniformly and then aged to obtain a zinc oxide sol;

[0080] Step 2, the zinc oxide sol is dip-coated onto the surface of a substrate, and then heat treated to obtain a sample with a zinc oxide coating;

[0081] ​Step 3, the zinc salt and hexamethylenetetramine are stirred in water to obtain a nanorod growth solution, and the sample with the zinc oxide coating is placed in the nanorod growth solution to obtain a sample with a zinc oxide nanorod array film layer;

[0082] Step 4, the organic ligand of the metal organic framework, the corrosion inhibitor and sodium formate are stirred in water to obtain a metal organic framework growth solution, and the sample with the zinc oxide nanorod array film layer is placed in the metal organic framework growth solution to obtain a sample loaded with the metal organic framework;

[0083] Step 5, water, ethanol and organosilane are mixed to obtain solution 1, ethanol, ethyl acetoacetate and tetraethyl orthosilicate are stirred to obtain solution 2, and solution 2 is added to solution 1 and stirred to obtain a silane sol after aging;

[0084] Step 6, the silane sol is sprayed on the sample loaded with the metal organic framework, and a composite protective film with corrosion warning effect is obtained after drying.

[0085] The above steps are described in detail as follows.

[0086] In step 1, the zinc salt and ethylene glycol methyl ether are stirred in water until the solution is clear, then the ethanolamine is added, and the reaction is carried out at 50-80℃ and a stirring speed of 400-800 rpm for 10-60 min, and then aged for 20-30 h.

[0087] Preferably, the ethanolamine is added, and the reaction is carried out at 60-70℃ and a stirring speed of 500-700 rpm for 10-30 min, and then aged for 24 h.

[0088] In step 2, the zinc oxide sol is dip-coated onto the surface of the substrate by dip-coating method, and the dip-coating rate is 40-90 mm / min, preferably 42-80 mm / min.

[0089] The dip-coating is performed twice, and the dip-coating time of each time is 3-8 min, preferably 5 min.

[0090] After the first dip-coating, the sample is dried at 40-70℃ for 45-75 min, preferably at 45-60℃ for 60 min.

[0091] After the second dip-coating, the sample is heat treated, and the heat treatment is performed in a gradient heating mode, and the temperature is raised to 200-600℃ at a heating rate of 0.5℃ / min-2.5℃ / min, and the temperature is kept at the highest temperature for 100-300 min.

[0092] Preferably, the temperature is raised to 200-600℃ at a heating rate of 0.5℃ / min-1℃ / min, and the temperature is kept at the highest temperature for 200 min.

[0093] In step 3, the sample with zinc oxide coating is placed in the nanorod growth solution and heated to 80-200℃ for 4-7h, preferably heated to 85-150℃ for 5-6h.

[0094] In step 4, the amount of water added is not particularly limited, as long as the solute therein can be completely dissolved.

[0095] In step 4, the amount of water added is not particularly limited, as long as the solute therein can be completely dissolved.

[0096] In step 5, water, ethanol and organosilane are mixed and stirred at 300-700rpm for 10-60min.

[0097] In step 5, water, ethanol and organosilane are mixed and stirred at 300-700rpm for 10-60min.

[0098] In step 5, water, ethanol and organosilane are mixed and stirred at 300-700rpm for 10-60min.

[0099] In step 6, the spraying pressure of the silane sol is 3-10kPa, preferably 4-8kPa.

[0100] The drying temperature is 60-120℃ and the drying time is 2-6h.

[0101] The preparation method of the present application introduces a zinc oxide nanoparticle layer (ZnO NP) on the surface of an aluminum alloy (substrate) and further grows it into a zinc oxide nanorod layer (ZnO NR). At the same time, the ZnO NR can also serve as a source of metal ions for the subsequent metal organic framework (MOF), inducing the growth of the metal organic framework in a manner of dissolving and releasing zinc ions, and loading corrosion inhibitors during the growth process to achieve synergistic corrosion resistance. Finally, a layer of silane gel network (sprayed silane sol) is capped on the surface layer to seal the surface defects of the metal organic framework film layer, while solving the problems of poor adhesion and easy peeling of the metal organic framework film layer. The different film layers of the protective film layer have different fluorescence phenomena, which can realize the intuitive observation of the damage condition of the film layer under ultraviolet light, and have the function of self-warning before the substrate is corroded.

[0102] Examples

[0103] The present application is further described below by specific examples, which are only limited to illustrate the present application, and are not used to limit the scope of the present application.

[0104] The raw materials used in the examples of the present application are all purchased.

[0105] Example 1

[0106] Step 1, 16 g zinc acetate, 95.32 g ethylene glycol methyl ether were added into deionized water and stirred uniformly, after clarification, 5.55 g ethanolamine was added dropwise, and the reaction was carried out at 70°C and 500 rpm for 10 min, after the reaction was completed, the clear solution was aged for 24 h to obtain a zinc oxide sol.

[0107] Step 2, the zinc oxide sol was introduced to the surface of the substrate by dip-coating method twice with a pulling rate of 42 mm / min, each time soaking for 5 min, wherein after the first pulling was completed, the sample was dried at 50°C for 60 min, after the two times of pulling treatment, the sample was placed in a muffle furnace and heated with the furnace at a temperature increasing rate of 1°C / min to 200°C, then at a temperature increasing rate of 0.5°C / min to 300°C, and then at a temperature increasing rate of 1°C / min to 400°C, and kept at 400°C for 200 min, after cooling with the furnace, a ZnO NP sample coated with a uniform zinc oxide nanoparticle gel layer was obtained, which could be rinsed with deionized water to remove unreacted residues and then blown dry.

[0108] Step 3, 0.669 g zinc nitrate, 0.389 g hexamethylenetetramine were added into 50 mL deionized water to prepare a nanorod growth solution, the nanorod growth solution was stirred uniformly and placed in a high-pressure hydrothermal kettle, the ZnO NP sample was placed in the high-pressure hydrothermal kettle and heated at 85°C for 5 h, then taken out to obtain a ZnO NR sample with a zinc oxide nanorod array film layer on the surface, which could be rinsed with deionized water to remove unreacted residues and then blown dry.

[0109] Step 4, 9.72 g 2-methylimidazole, 0.1673 g 2-mercaptobenzothiazole and 4.035 g sodium formate were added into 400 mL deionized water, stirred uniformly to dissolve, the ZnO NR sample with a zinc oxide nanorod array film layer on the surface was placed in the solution and reacted at 85°C for 5 min, then taken out to obtain a sample ZnO / ZIF-8@MBT coated with a ZIF-8 film loaded with MBT on the surface, which could be rinsed with deionized water and ethanol to remove unreacted residues and then blown dry.

[0110] Step 5, 14 mL deionized water, 30 mL anhydrous ethanol were mixed thoroughly at room temperature, then 24 mL 3-glycidyloxypropyltrimethoxysilane (solution 1) was slowly added, and stirred at a speed of 300 rpm for 15 min; 12 mL anhydrous ethanol, 6 mL ethyl acetoacetate and 12 mL tetraethyl silicate were uniformly mixed, and 1.2 mL glacial acetic acid was added to adjust the pH (solution 2), stirred at a speed of 300 rpm for 1 h, solution 2 was added dropwise into solution 1, and aged at room temperature with stirring at 500 rpm for 24 h to obtain a silane sol.

[0111] Step 6, the obtained silane sol is sprayed on the surface of the ZnO / ZIF-8@MBT sample under a pressure of 6 kPa, and the sample is dried in a drying oven at 60 ℃ for 2 h, at 90 ℃ for 1 h, and at 120 ℃ for 30 min, and then cooled to room temperature in the drying oven to obtain a sample ZnO / ZIF-8@MBT / SG with a composite film layer.

[0112] The sample ZnO / ZIF-8@MBT / SG with a composite film layer prepared in Example 1 is subjected to scanning electron microscope-energy spectrum (SEM-EDS) test, and the test results are shown in Figure 2 Figure 2 The electron microscope photos and energy spectrum diagrams of the ZnO NP film layer, the ZnO NR film layer, the ZnO / ZIF-8@MBT film layer and the ZnO / ZIF-8@MBT / SG film layer are shown in

[0113] The composite film layer prepared in Example 1 is subjected to fluorescence test, and the test results are shown in Figure 3 It can be seen that (a) is a fluorescence photo before corrosion, which is strong blue fluorescence; (b) is a fluorescence photo after preliminary corrosion, the blue color becomes weak, and the selected part starts to appear yellow fluorescence of the next layer; (c) is a fluorescence photo after intensified corrosion, the blue fluorescence further becomes weak, and the selected part yellow fluorescence is strengthened; (d) is a fluorescence photo after further intensified corrosion, the selected part yellow fluorescence basically realizes coverage, and only partial blue fluorescence exists; (e) is a fluorescence photo after complete corrosion, the fluorescence basically disappears, and only residual fluorescence phenomenon exists at partial positions, indicating that the protective film layer has a corrosion early warning effect.

[0114] Example 2

[0115] Step 1, 16 g of zinc chloride and 122.7 g of ethylene glycol methyl ether are uniformly stirred in deionized water, 8 g of ethanolamine is added dropwise after clarification, and the reaction is carried out at 70 ℃ and 500 rpm for 20 min, and the clarified solution is aged for 30 h to obtain a zinc oxide sol.

[0116] ​Step 2, dip the substrate into the zinc oxide sol for twice with a pulling rate of 60 mm / min and each time for 5 min, after the first pulling, dry the substrate at 60 °C for 60 min, after the twice pulling, heat the sample to 300 °C at a rate of 1 °C / min, then heat to 500 °C at a rate of 0.5 °C / min, and keep at 500 °C for 200 min, after cooling down to room temperature, the sample coated with a uniform zinc oxide nanoparticle gel layer is obtained, which can be rinsed with deionized water and then dried.

[0117] Step 3, prepare a nanorod growth solution by adding 0.669 g zinc sulfate and 0.389 g hexamethylenetetramine into 50 mL deionized water, uniformly stir the nanorod growth solution and place it in a high-pressure hydrothermal kettle, put the ZnO NP sample into the high-pressure hydrothermal kettle and heat at 150 °C for 6 h, then take it out, to obtain a sample ZnO NR with a zinc oxide nanorod array film layer on the surface. The sample can be rinsed with deionized water and then dried.

[0118] Step 4, add 9.72 g 2,5-furan dicarboxylic acid, 0.6372 g 8-hydroxyquinoline and 3.535 g sodium formate into 400 mL deionized water, uniformly stir to dissolve, place the obtained ZnO NR sample into the solution and react at 70 °C for 30 min, then take it out, to obtain a sample ZnO / Zn-MOF@HQ coated with a Zn-MOF thin film loaded with 8-HQ on the surface. The sample can be rinsed with deionized water and ethanol and then dried.

[0119] Step 5, after mixing 15 mL deionized water and 45 mL anhydrous ethanol at room temperature, slowly add 45 mL methacryloxypropyltrimethoxysilane (solution 1) and keep stirring at a speed of 700 rpm for 30 min; uniformly mix 24 mL anhydrous ethanol, 6 mL ethyl acetoacetate and 20 mL tetraethyl silicate, and add 1.5 mL glacial acetic acid to adjust the pH (solution 2), keep stirring at a speed of 700 rpm for 1 h, add solution 2 dropwise into solution 1, and keep stirring at a speed of 900 rpm at room temperature for 24 h to perform aging, to obtain a silane sol.

[0120] Step 6, spray the obtained silane sol on the surface of the ZnO / Zn-MOF@HQ sample under a pressure of 4 kPa, dry in a drying oven at 60 °C for 2 h and at 120 °C for 1 h, and then cool down to room temperature, to obtain a sample ZnO / Zn-MOF@HQ / SG with a composite film layer.

[0121] Example 3

[0122] Step 1, 16 g of zinc sulfate, 186.67 g of ethylene glycol methyl ether were added into deionized water and stirred uniformly, after clarification, 9.5 g of ethanolamine was added dropwise, and the reaction was carried out at 60°C and 700 rpm for 40 min, and the clear solution was aged for 20 h to obtain a zinc oxide sol.

[0123] Step 2, the zinc oxide sol was introduced to the surface of the substrate by dip-coating method at a pulling rate of 80 mm / min for two times, each time for 5 min, after the first time, the sample was dried at 45°C for 60 min, after the two times of pulling treatment, the sample was placed in a muffle furnace and heated to 200°C at a rate of 1°C / min, then heated to 400°C at a rate of 0.5°C / min, then heated to 600°C at a rate of 1°C / min, and kept at 600°C for 200 min, and then cooled in the furnace to obtain a ZnO NP sample coated with a uniform zinc oxide nanoparticle gel layer. The sample can be rinsed with deionized water to remove unreacted residues and then blown dry.

[0124] Step 3, 0.669 g of zinc bromide, 0.389 g of hexamethylenetetramine were added to 50 mL of deionized water to prepare a nanorod growth solution. The nanorod growth solution was stirred uniformly and placed in a high-pressure hydrothermal kettle, the obtained ZnO NP sample was placed in the high-pressure hydrothermal kettle and heated at 100°C for 6 h, then taken out to obtain a sample ZnO NR with a zinc oxide nanorod array film layer on the surface. The sample can be rinsed with deionized water to remove unreacted residues and then blown dry.

[0125] Step 4, 9.72 g of terephthalic acid, 0.7058 g of benzotriazole and 2.773 g of sodium formate were added to 400 mL of deionized water, stirred uniformly to dissolve, the obtained ZnO NR sample was placed in the solution and reacted at 90°C for 10 min, then taken out to obtain a sample ZnO / Zn-MOF@BTA coated with a Zn-MOF film loaded with BTA on the surface. The sample can be rinsed with deionized water and ethanol to remove unreacted residues and then blown dry.

[0126] Step 5, 20 mL of deionized water, 20 mL of anhydrous ethanol were mixed thoroughly at room temperature, then 24 mL of aminopropyl triethoxysilane (solution 1) was slowly added, and stirred at a speed of 500 rpm for 50 min; 24 mL of anhydrous ethanol, 6 mL of ethyl acetoacetate and 12 mL of tetraethyl silicate (TEOS) were uniformly mixed, and 1.9 mL of glacial acetic acid was added to adjust the pH (solution 2), and stirred at a speed of 500 rpm for 1 h, then solution 2 was added dropwise into solution 1, and aged at room temperature with stirring at 700 rpm for 24 h to obtain a silane sol.

[0127] Step 6, the obtained silane sol was sprayed on the surface of the obtained ZnO / ZIF-8@BTA sample at a pressure of 8 kPa, and dried in a drying oven at 70 °C for 1 h, 100 °C for 1 h, and 120 °C for 1 h, and then cooled to room temperature in the drying oven to obtain a sample ZnO / Zn-MOF@BTA / SG with a composite film layer.

[0128] Comparative Example

[0129] Comparative Example 1

[0130] Step 1, 16 g of zinc acetate and 95.32 g of ethylene glycol methyl ether were added to deionized water and stirred uniformly, and after clarification, 5.55 g of ethanolamine was added dropwise, and the reaction was carried out at 70 °C and a stirring speed of 500 rpm for 10 min. After the reaction was completed, the clear solution was aged for 24 h to obtain a zinc oxide sol.

[0131] Step 2, the zinc oxide sol was introduced to the surface of the substrate by the dip-coating method twice at a pulling rate of 42 mm / min, each time soaking for 5 min, wherein after the first pulling was completed, the sample was dried at 50 °C for 60 min, and after the twice pulling treatment, the sample was placed in a muffle furnace and heated to 200 °C at a heating rate of 1 °C / min, then heated to 300 °C at a heating rate of 0.5 °C / min, then heated to 400 °C at a heating rate of 1 °C / min, and kept at 400 °C for 200 min, and then cooled in the furnace to obtain a ZnO NP sample coated with a uniform zinc oxide nanoparticle gel layer, which can be rinsed with deionized water to remove unreacted residues and then blown dry.

[0132] Comparative Example 2

[0133] Step 1, 16 g of zinc acetate and 95.32 g of ethylene glycol methyl ether were added to deionized water and stirred uniformly, and after clarification, 5.55 g of ethanolamine was added dropwise, and the reaction was carried out at 70 °C and a stirring speed of 500 rpm for 10 min. After the reaction was completed, the clear solution was aged for 24 h to obtain a zinc oxide sol.

[0134] Step 2, the zinc oxide sol was introduced to the surface of the substrate by the dip-coating method twice at a pulling rate of 42 mm / min, each time soaking for 5 min, wherein after the first pulling was completed, the sample was dried at 50 °C for 60 min, and after the twice pulling treatment, the sample was placed in a muffle furnace and heated to 200 °C at a heating rate of 1 °C / min, then heated to 300 °C at a heating rate of 0.5 °C / min, then heated to 400 °C at a heating rate of 1 °C / min, and kept at 400 °C for 200 min, and then cooled in the furnace to obtain a ZnO NP sample coated with a uniform zinc oxide nanoparticle gel layer, which can be rinsed with deionized water to remove unreacted residues and then blown dry.

[0135] Step 3, prepare nanorod growth solution by adding 0.669 g zinc nitrate and 0.389 g hexamethylenetetramine into 50 mL deionized water, uniformly stir the nanorod growth solution and place it in a high-pressure hydrothermal kettle, place the ZnO NP sample in the high-pressure hydrothermal kettle, heat it at 85°C for 5 h, then take it out, to obtain a ZnO NR sample with a zinc oxide nanorod array film layer on the surface, which can be rinsed with deionized water to remove unreacted residues and then dried.

[0136] Comparative Example 3

[0137] Step 1, uniformly stir 16 g zinc acetate and 95.32 g ethylene glycol methyl ether in deionized water, then dropwise add 5.55 g ethanolamine after clarification, and keep the stirring speed at 70°C and 500 rpm for 10 min, after the reaction is completed, the clear solution is aged for 24 h to obtain a zinc oxide sol.

[0138] Step 2, use the dip-coating method to draw the zinc oxide sol to the surface of the substrate twice at a drawing rate of 42 mm / min, each time soaking for 5 min, after the first drawing is completed, dry it at 50°C for 60 min, after the two drawing treatments, place the sample in a muffle furnace and heat it with the furnace at a temperature increasing rate of 1°C / min to 200°C, then at a temperature increasing rate of 0.5°C / min to 300°C, then at a temperature increasing rate of 1°C / min to 400°C, and keep it at 400°C for 200 min, after cooling with the furnace, obtain a ZnO NP sample coated with a uniform zinc oxide nanoparticle gel layer, which can be rinsed with deionized water to remove unreacted residues and then dried.

[0139] Step 3, prepare nanorod growth solution by adding 0.669 g zinc nitrate and 0.389 g hexamethylenetetramine into 50 mL deionized water, uniformly stir the nanorod growth solution and place it in a high-pressure hydrothermal kettle, place the ZnO NP sample in the high-pressure hydrothermal kettle, heat it at 85°C for 5 h, then take it out, to obtain a ZnO NR sample with a zinc oxide nanorod array film layer on the surface, which can be rinsed with deionized water to remove unreacted residues and then dried.

[0140] Step 4, add 9.72 g 2-methylimidazole, 0.1673 g 2-mercaptobenzothiazole and 4.035 g sodium formate into 400 mL deionized water, uniformly stir to dissolve, place the ZnO NR sample with a zinc oxide nanorod array film layer on the surface in the solution, react at 85°C for 5 min, then take it out, to obtain a sample ZnO / ZIF-8@MBT coated with a ZIF-8 film loaded with MBT on the surface, which can be rinsed with deionized water and ethanol to remove unreacted residues and then dried.

[0141] The fluorescence tests of Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 are shown in the following table.Figure 4 As shown. From Figure 4 As can be seen from the results, under a fluorescence microscope, the ZnO NP film prepared in Comparative Example 1 did not exhibit fluorescence under ultraviolet light excitation; the ZnO NR film prepared in Comparative Example 2 showed weak yellow fluorescence; the ZnO / ZIF-8@MBT film prepared in Comparative Example 3 showed more uniform and dense yellow fluorescence; and the ZnO / ZIF-8@MBT / SG composite protective film prepared in Example 1 showed blue fluorescence. This indicates that the fluorescence between different layers of the film has a distinguishable indicative effect, further verifying that the composite protective film prepared in this invention has a corrosion self-warning function.

[0142] Experimental Example

[0143] Experiment Example 1: Electrochemical Testing

[0144] Electrochemical performance tests were conducted on the films prepared in Example 1 and Comparative Examples 1-3. The testing procedure was as follows: Electrochemical impedance spectroscopy (EIS) was performed using a Wuhan Corrtest CS350 electrochemical workstation. A three-electrode system was used for all tests, with the sample as the working electrode, Ag / AgCl as the reference electrode, and a platinum mesh as the counter electrode. The test solution was a 3.5 wt% NaCl aqueous solution, and the test area was 1 cm². 2 The sample area to be tested was immersed in the solution, and the open-circuit potential was measured until the potential fluctuation was less than or equal to ±0.05V before electrochemical impedance spectroscopy was performed. The test results are as follows: Figure 5 As shown, Figure 5 AA2024 is an aluminum alloy substrate, ZnO NP is the film layer prepared in Comparative Example 1, ZnO NR is the film layer prepared in Comparative Example 2, ZnO / ZIF-8@MBT is the film layer prepared in Comparative Example 3, and ZnO / ZIF-8@MBT / SG is the film layer prepared in Example 1.

[0145] from Figure 5 As can be seen from the electrochemical test results, the corrosion resistance of the ZnO NP film sample prepared in Comparative Example 1 is slightly improved compared to the 2024 aluminum alloy substrate. After preparing the nanorod film, the rod-like array structure of the ZnO NR film (Comparative Example 2) resulted in a porous electrode electrochemical state, leading to a decrease in shielding performance. However, after preparing the metal-organic framework film loaded with corrosion inhibitor, the low-frequency impedance modulus of the ZnO / ZIF-8@MBT film sample (Comparative Example 3) was increased by an order of magnitude compared to the ZnO NP and ZnO NR films, indicating improved corrosion resistance. Finally, the low-frequency impedance modulus of the complete ZnO / ZIF-8@MBT / SG protective film sample prepared in Example 1 was again increased by nearly an order of magnitude compared to the ZnO / ZIF-8@MBT film, indicating further improvement in corrosion resistance.

[0146] The present application has been described in detail by reference to particular embodiments and illustrative examples, but these are not intended to limit the present application to the details described herein. Various modifications and equivalents can occur to one skilled in the art without departing from the spirit and scope of the present application, and it is understood that the present application is intended to cover what falls within the scope of the appended claims.

Claims

1. A composite protective film with corrosion warning effect, characterized in that, according to the coating sequence of the protective film, the composite protective film comprises, from bottom to top, a metal oxide-based composite film layer, a metal organic framework film layer and an organosilica gel film layer, wherein, the preparation raw materials of the metal oxide-based composite film layer comprise zinc salt, ethylene glycol methyl ether, ethanolamine and hexamethylenetetramine; the metal organic framework film layer is loaded with corrosion inhibitor, and the preparation raw materials of the metal organic framework film layer comprise organic ligand of metal organic framework, corrosion inhibitor and sodium formate; the preparation raw materials of the organosilica gel film layer comprise solution 1 and solution 2, the solution 1 is prepared from water, ethanol and organosilane, and the solution 2 is prepared from ethanol, ethyl acetoacetate and tetraethyl silicate; the composite protective film is prepared by the following steps: step 1, zinc salt, ethylene glycol methyl ether and ethanolamine are added into water, stirred uniformly, and then aged to obtain zinc oxide sol; step 2, the zinc oxide sol is dip-coated on the surface of a substrate, and then heat-treated to obtain a sample with zinc oxide coating; step 3, zinc salt and hexamethylenetetramine are added into water and stirred uniformly to obtain nanorod growth solution, and the sample with zinc oxide coating is placed in the nanorod growth solution to obtain a sample with zinc oxide nanorod array film layer; step 4, organic ligand of metal organic framework, corrosion inhibitor and sodium formate are added into water and stirred uniformly to obtain metal organic framework growth solution, and the sample with zinc oxide nanorod array film layer is placed in the metal organic framework growth solution to obtain a sample loaded with metal organic framework; step 5, water, ethanol and organosilane are mixed uniformly to obtain solution 1, and ethanol, ethyl acetoacetate and tetraethyl silicate are stirred uniformly, and then adjusted in pH to obtain solution 2, and the solution 2 is added into the solution 1 and stirred, and then aged to obtain silane sol; step 6, the silane sol is sprayed on the sample loaded with metal organic framework, and then dried to obtain the composite protective film with corrosion warning effect. 2.The composite protective film with corrosion warning effect according to claim 1, characterized in that, the zinc salt is selected from one or more of zinc acetate, zinc sulfate, zinc nitrate, zinc chloride, zinc bromide and zinc iodide; and / or, the organic ligand of metal organic framework is selected from one or more of 2, 5-furandicarboxylic acid, terephthalic acid, 1, 3, 5-benzenetricarboxylic acid and 2-methylimidazole; and / or, the corrosion inhibitor is selected from one or more of 8-hydroxyquinoline, benzotriazole, 2-mercaptobenzothiazole and coumarin; and / or, the organosilane is selected from one or more of aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, N, N-diethyl-3-aminopropyltrimethoxysilane and vinyltriethoxysilane. 3.The composite protective film with corrosion warning effect according to claim 1, characterized in that, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The mass ratio of the zinc salt, ethylene glycol methyl ether and ethanolamine is 1: (4-15): (0.2-0.7); and / or, The mass ratio of the zinc salt and hexamethylenetetramine is 1: (0.4-0.7); and / or, The mass ratio of the organic ligand of the metal organic framework, the corrosion inhibitor and sodium formate is (10-65):1: (2-30); and / or, The volume ratio of solution 1 and solution 2 is (1-3):1; and / or, The volume ratio of the water, ethanol and organosilane is 1: (1-4): (1-4); and / or, The volume ratio of the ethanol, ethyl acetoacetate and tetraethyl silicate is (1-5):1: (1-4).

4. A method for producing the composite protective film having a corrosion warning effect according to any one of claims 1 to 3, characterized by, The preparation method comprises the following steps: Step 1, zinc salt, ethylene glycol methyl ether and ethanolamine are added into water, stirred uniformly, and then aged to obtain a zinc oxide sol; Step 2, the zinc oxide sol is dip-coated onto the surface of a substrate, and then heat treated to obtain a sample with a zinc oxide coating; Step 3, zinc salt and hexamethylenetetramine are stirred uniformly in water to obtain a nanorod growth solution, and the sample with the zinc oxide coating is placed in the nanorod growth solution to obtain a sample with a zinc oxide nanorod array film layer; Step 4, the organic ligand of the metal organic framework, the corrosion inhibitor and sodium formate are stirred uniformly in water to obtain a metal organic framework growth solution, and the sample with the zinc oxide nanorod array film layer is placed in the metal organic framework growth solution to obtain a sample loaded with the metal organic framework; Step 5, the water, ethanol and organosilane are mixed uniformly to obtain solution 1, the ethanol, ethyl acetoacetate and tetraethyl silicate are stirred uniformly, and then solution 2 is obtained after adjusting the pH, solution 2 is added into solution 1, stirred and then aged to obtain a silane sol; Step 6, the silane sol is sprayed on the sample loaded with the metal organic framework, and then dried to obtain a composite protective film with corrosion early warning effect; In step 3, the sample with the zinc oxide coating is placed in the nanorod growth solution, heated to 80-200℃ and kept for 4-7h.

5. The preparation method according to claim 4, wherein The zinc salt and ethylene glycol methyl ether are stirred uniformly in water until the solution is clear, then the ethanolamine is added, reacted at 50-80℃ and a stirring speed of 400-800rpm for 10-60min, and then aged for 20-30h.

6. The preparation method according to claim 4, characterized in that, In step 2, The zinc oxide sol is dip-coated onto the surface of a substrate by using the dip-coating method, and the dip-coating rate is 40-90mm / min; and / or, The dip-coating is performed twice, and the dip-coating time of each time is 3-8min; and / or, After the first dip-coating, the sample is dried at 40-70℃ for 45-75min; and / or, After the second dip-coating, the sample is heat treated, and the heat treatment is performed by using the gradient heating method, the heating rate is 0.5℃ / min-2.5℃ / min, the temperature is increased to 200-600℃, and then kept for 100-300min after increasing to the highest temperature.

7. The preparation method according to claim 4, characterized in that, In step 4, The sample with the zinc oxide nanorod array film layer is placed in the metal organic framework growth solution, heated to 50-100℃ and kept for 3-40min.

8. The preparation method according to claim 4, characterized in that, In step 5, mixing water, ethanol and organosilane under stirring at 300-700 rpm for 10-60 min; and / or, mixing ethanol, ethyl acetoacetate and tetraethyl silicate under stirring at 300-700 rpm for 1 h; and / or, adding solution 2 to solution 1 under stirring at 500-900 rpm for 24 h.

9. The preparation method according to claim 4, characterized in that, in step 6, the spraying pressure of the silane sol is 3-10 kPa; and / or, the temperature of the drying is 60-120 °C.

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