Hydrophobically modified anticorrosive coating and method of making same

Abstract

The application discloses a kind of hydrophobic modified anticorrosive coating and preparation method thereof, the method for preparing hydrophobic modified anticorrosive coating includes: anticorrosive coating is soaked in PDMS homogeneous solution, stationary, solidification, obtains hydrophobic modified anticorrosive coating, the preparation of anticorrosive coating includes: coating is scraped, dry, solidification, obtains anticorrosive coating, wherein, the preparation method of coating includes: g-C3N4 is etched in acidic solution, ultrasonic, obtains etching g-C3N4;Etching g-C3N4, aniline and water are mixed, adjust pH, obtain the polyaniline precursor solution of pH 1~4, polyaniline precursor solution is photopolymerization, obtains second precipitation, washes, freeze-drying, obtains polyaniline composite nanomaterial;Polyaniline composite nanomaterial is dispersed in waterborne epoxy resin, first stirring is then ultrasonic, obtains first solution, first solution and curing agent are mixed to be uniform, obtain coating.The hydrophobic modified anticorrosive coating of the application has the advantages of corrosion resistance, ultraviolet resistance, algae resistance, high hydrophobicity and long service life.

Description

Technical Field

[0001] This invention belongs to the field of environmental and anti-corrosion technology, specifically relating to a hydrophobic modified anti-corrosion coating and its preparation method. Background Technology

[0002] Polyaniline (PANI) is used as a corrosion inhibitor in coatings due to its higher redox potential than that of iron. When PANI and iron come into contact, a redox reaction occurs with the participation of water and oxygen, forming a dense metallic oxide film at the interface. The positive potential of the PANI structure can interact with the negative charge of algal cell walls, thereby preventing algae from adhering to the PANI-based coating surface. However, the effectiveness and applicability of PANI are hindered by inherent shortcomings such as insufficient solubility, adhesion, and density. Therefore, PANI must be modified to enhance its suitability for anti-corrosion and anti-fouling purposes. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a coating. The method involves etching g-C3N4 with an acidic solution to obtain etched g-C3N4 (ECN), and then photo-initiated polymerization of ECN and aniline (ANI) to generate a polyaniline nanocomposite material ECN@PANI, thereby obtaining the coating.

[0004] Another object of the present invention is to provide a coating obtained by the above preparation method, which can simultaneously have long life, UV resistance and algae resistance.

[0005] Another object of the present invention is to provide a method for preparing a hydrophobic modified anti-corrosion coating.

[0006] Another object of the present invention is to provide a hydrophobic modified anti-corrosion coating obtained by the above method.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] A method for preparing a coating includes the following steps:

[0009] Step 1: Etch g-C3N4 in an acidic solution to obtain a first precipitate. Sonicate the first precipitate to obtain etched g-C3N4 (ECN).

[0010] In step 1, the method for obtaining the g-C3N4 is as follows: urea and melamine are mixed evenly, calcined at 300-600℃ for 1-4 hours, and cooled to room temperature to obtain g-C3N4, wherein the ratio of urea to melamine by mass is (1-3):(1-3).

[0011] In the above technical solution, the heating rate to 300–600℃ is 1–4℃ / min. -1 .

[0012] In step 1, the etching includes:

[0013] 1. Repeat the following steps 5 to 10 times: Place g-C3N4 in an acidic solution and stir at 60 to 80°C for 0.5 to 1 hour, then sonicate at 40 to 80°C for 1 to 1.5 hours.

[0014] 2. Let stand for 10–30 hours, then centrifuge to obtain the first precipitate.

[0015] In step 1, the acidic solution is concentrated nitric acid.

[0016] In step 1, the ultrasound duration is 5 to 15 hours, and the ultrasound temperature is 40 to 80°C.

[0017] In step 1, the ultrasound is performed in ethanol or water.

[0018] Step 2: Mix etched g-C3N4 (ECN), aniline (ANI), and water, adjust the pH, and stir until homogeneous to obtain a liquid with a pH of 1-4 as a polyaniline precursor solution. Incubate the polyaniline precursor solution at 10-40°C for 4-8 hours using photopolymerization. Centrifuge to obtain a second precipitate. Wash the second precipitate and freeze-dry to obtain the polyaniline composite nanomaterial ECN@PANI. The ratio of the mass fraction of etched g-C3N4 (ECN), the volume fraction of aniline (ANI), and the volume fraction of the polyaniline precursor solution is 0.08:(10-20):300. The mass fraction is expressed in g, and the volume fraction is expressed in mL.

[0019] In step 2, the photopolymerization reaction is carried out using a mercury lamp with a power of 300-500W.

[0020] Step 3: Disperse the polyaniline composite nanomaterial ECN@PANI in waterborne epoxy resin (WEP), stir and then sonicate to obtain a first solution. Mix the first solution and curing agent (CA) until uniform to obtain a coating. The polyaniline composite nanomaterial ECN@PANI is 1-3 wt% of the sum of waterborne epoxy resin (WEP) and curing agent (CA). By volume, the ratio of waterborne epoxy resin (WEP) to curing agent (CA) is (1-6):1. The curing agent (CA) is used to cure the waterborne epoxy resin (WEP).

[0021] In step 3, the stirring time is 10-30 minutes, and the ultrasonic time is 30-60 minutes.

[0022] The coating obtained by the above preparation method.

[0023] A method for preparing an anti-corrosion coating includes: applying the coating material onto a surface, drying, and curing to obtain an anti-corrosion coating on the surface.

[0024] In the above technical solution, the drying temperature is room temperature, and the drying time is at least 12 hours.

[0025] In the above technical solution, the curing temperature is 60-80℃ and the curing time is at least 5 hours.

[0026] In the above technical solution, the thickness of the anti-corrosion coating is at least 50 μm, preferably 80–150 μm, and even more preferably 90–110 μm.

[0027] The anti-corrosion coating obtained by the above preparation method.

[0028] A method for preparing a hydrophobic modified anticorrosive coating includes: immersing the anticorrosive coating in a homogeneous PDMS solution for 0.5–1.5 h, allowing it to stand to evaporate n-hexane, and curing it at 60–80 °C for 5–10 h to obtain the hydrophobic modified anticorrosive coating, wherein the homogeneous PDMS solution is a mixture of PDMS bicomponents and n-hexane.

[0029] In the method for preparing hydrophobic modified anti-corrosion coatings, the settling temperature is room temperature and the settling time is 12 to 48 hours.

[0030] In the above technical solution, the ratio of the PDMS bicomponent to n-hexane by volume is (1-5):100.

[0031] In the above technical solution, the PDMS two-component includes Part A and Part B, Part A is a prepolymer, and Part B is used to cure Part A. By volume, the ratio of Part A to Part B is (5~15):1.

[0032] The hydrophobic modified anti-corrosion coating obtained by the above method.

[0033] The anti-corrosion coating of the present invention not only has excellent anti-corrosion performance, but also has the advantages of UV resistance, algae resistance and long service life. At the same time, the hydrophobic modified anti-corrosion coating not only inherits all the advantages of the anti-corrosion coating, but also endows it with high hydrophobicity. Attached Figure Description

[0034] Figure 1 'a' is a scanning electron microscope image of CN. Figure 1 b is a scanning electron microscope image of ECN;

[0035] Figure 2The images are digital photographs of CN, ECN, PANI purchased from Aladdin, PANI prepared in Example 6, and ECN@PANI prepared in Example 2, respectively, after being placed in WEP for 7 days.

[0036] Figure 3 Nyquist images of the anti-corrosion coatings prepared in Examples 1-3, CN / WEP prepared in Example 4, ECN / WEP prepared in Example 5, PANI / WEP prepared in Example 6, and WEP prepared in Example 7 after immersion in 3.5wt% NaCl aqueous solution for 1 day;

[0037] Figure 4 Nyquist images of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7 after immersion in 3.5wt% NaCl aqueous solution for 1 day;

[0038] Figure 5 Bode images of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7 after immersion in 3.5wt% NaCl aqueous solution for 1 day.

[0039] Figure 6 Nyquist images of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7 after immersion in 3.5wt% NaCl aqueous solution for 90 days.

[0040] Figure 7 The impedance modulus (|Z|) of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, Example 5 (ECN / HWEP), Example 6 (PANI / HWEP), and Example 7 (HWEP) after immersion in a 3.5 wt% NaCl aqueous solution for 90 days is determined. 0.01Hz ) and the frequency F where the maximum phase angle is located m ;

[0041] Figure 8Nyquist images of the hydrophobic modified anticorrosive coatings prepared in Example 2, PANI / HWEP prepared in Example 6, ECN / HWEP prepared in Example 5, and HWEP prepared in Example 7 after UV irradiation.

[0042] Figure 9 The impedance modulus (|Z|) of the hydrophobic modified anti-corrosion coatings HWEP prepared in Example 7, ECN / HWEP prepared in Example 5, PANI / HWEP prepared in Example 6, and the hydrophobic modified anti-corrosion coating prepared in Example 2 after UV radiation. 0.01Hz ) and the frequency F where the maximum phase angle is located m ;

[0043] Figure 10 Digital photographs of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the PANI / HWEP hydrophobic modified anticorrosive coating prepared in Example 6, the ECN / HWEP hydrophobic modified anticorrosive coating prepared in Example 5, and the HWEP hydrophobic modified anticorrosive coating prepared in Example 7 after a 30-day salt spray test. Figure 10 a to f are, in order, hydrophobic modified anti-corrosion coating HWEP, hydrophobic modified anti-corrosion coating ECN / HWEP, hydrophobic modified anti-corrosion coating PANI / HWEP, ECN@PANI / HWEP-1, ECN@PANI / HWEP-2 and ECN@PANI / HWEP-3;

[0044] Figure 11 The contact angles of the hydrophobic modified anti-corrosion coating HWEP prepared in Example 7, the hydrophobic modified anti-corrosion coating ECN / HWEP prepared in Example 5, the hydrophobic modified anti-corrosion coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anti-corrosion coating prepared in Example 2 before and after ultraviolet radiation, where before radiation is Before UV and after radiation is After UV.

[0045] Figure 12 The hydrophobic modified anti-corrosion coating HWEP prepared in Example 7 ( Figure 12 a) The hydrophobic modified anti-corrosion coating ECN / HWEP prepared in Example 5 Figure 12 (b) The hydrophobic modified anti-corrosion coating PANI / HWEP prepared in Example 6 Figure 12 c) and the hydrophobic modified anti-corrosion coating prepared in Example 2 ( Figure 12 d) FESEM after standing in Chlorella culture medium for 14 days. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0047] This invention uses concentrated nitric acid to etch g-C3N4 to obtain etched g-C3N4 (ECN), and then photo-induced polymerization at 10-40℃ to generate polyaniline composite nanomaterial ECN@PANI. The polyaniline composite nanomaterial ECN@PANI is uniformly dispersed in water-based epoxy resin and formed into an anti-corrosion coating (ECN@PANI / WEP) on the surface of Q235 carbon steel. The anti-corrosion coating has anti-ultraviolet and anti-algae properties. The anti-corrosion coating is immersed in a homogeneous PDMS solution to prepare a hydrophobic modified anti-corrosion coating. The aim is to improve the anti-corrosion performance of the coating while giving it hydrophobic properties, thereby extending its service life.

[0048] In the following embodiments, Q235 carbon steel was polished with sandpaper of 500 grit, 1000 grit, 1500 grit and 2000 grit in sequence before use to remove the surface oxide layer; then it was washed with ethanol.

[0049] In the following embodiments, the method for obtaining g-C3N4 is as follows: urea and melamine are mixed in a mortar and ground thoroughly (until powder is formed), then placed in a ceramic crucible, and the ceramic crucible is placed in a muffle furnace for calcination: calcined at 450°C for 3 hours (the heating rate to 450°C is 3°C / min). -1 After naturally cooling to room temperature, the urea was removed to obtain g-C3N4(CN) in the form of a blocky graphite phase. The ratio of urea to melamine by mass was 1:1.

[0050] The raw materials and their sources of purchase involved in the following embodiments are as follows:

[0051]

[0052]

[0053] Note: Waterborne epoxy resin and curing agent (CA) are a kit product.

[0054] The instruments and models involved in the following embodiments are as follows:

[0055]

[0056] Examples 1-3

[0057] A method for preparing a hydrophobic modified anticorrosive coating includes: immersing the anticorrosive coating in a homogeneous PDMS solution for 1 hour, wherein the homogeneous PDMS solution is a mixture of a two-component PDMS and n-hexane; removing the coating after 1 hour and allowing it to stand at room temperature for 12 hours to allow the n-hexane to evaporate naturally; and curing the coating at 80°C for 8 hours to obtain the hydrophobic modified anticorrosive coating. The ratio of the two-component PDMS to n-hexane by volume is 1:100. The two-component PDMS includes Part A and Part B, where Part A is a prepolymer and Part B is used to cure Part A. The ratio of Part A to Part B by volume is 10:1.

[0058] The preparation method of the above-mentioned anti-corrosion coating includes: applying the coating to the surface of Q235 carbon steel using a fully CNC small coating machine (FA-202D), drying at room temperature for 24 hours, and curing at 80°C for 8 hours to obtain an anti-corrosion coating with a thickness of 100±10μm on the surface of Q235 carbon steel.

[0059] The preparation method of the above-mentioned coating includes the following steps:

[0060] Step 1: Etch g-C3N4 in concentrated nitric acid to obtain the first precipitate:

[0061] 1. Repeat the following steps 8 times: Place g-C3N4 in concentrated nitric acid, stir at 70°C for 1 hour, and then sonicate in a 70°C water bath for 1 hour;

[0062] 2. Let stand for 24 hours, then centrifuge to obtain the first precipitate;

[0063] The first precipitate was sonicated in anhydrous ethanol for 8 hours (in a 70°C water bath) to obtain ECN;

[0064] Step 2: Mix 0.08g ECN, 16mL aniline (ANI), and deionized water in a beaker. First, add 100mL of 5M nitric acid (HNO3), then add 1M nitric acid (HNO3) to adjust the pH. Stir until homogeneous, and bring the volume to 300mL to obtain a liquid with pH 2 as the polyaniline precursor solution. Transfer the polyaniline precursor solution into a quartz test tube and perform photopolymerization in a photochemical reactor (XPA-7 from Nanjing Xujiang Electromechanical Plant) for 6 hours (photopolymerization temperature is 25℃). After the photopolymerization reaction is completed, centrifuge to obtain a second precipitate. Wash the second precipitate with deionized water and freeze-dry to obtain the polyaniline composite nanomaterial ECN@PANI. The high-pressure mercury lamp in the photochemical reactor has a power of 500W, and the surface of the quartz test tube is fixed at a distance of 12cm from the high-pressure mercury lamp (this distance is horizontal).

[0065] Step 3: Disperse the polyaniline composite nanomaterial ECN@PANI in waterborne epoxy resin (WEP, 0704), stir for 30 min and then sonicate for 30 min to obtain the first solution. Mix the first solution and curing agent (CA, model 0705) until uniform to obtain the coating. The polyaniline composite nanomaterial ECN@PANI is X wt% of the sum of waterborne epoxy resin and curing agent (CA). The ratio of waterborne epoxy resin to curing agent is 5:1 by volume. The curing agent (CA) is used to cure the waterborne epoxy resin (WEP).

[0066]

[0067]

[0068] Example 4

[0069] A method for preparing an anti-corrosion coating (CN / WEP) includes the following steps:

[0070] Step 1: Disperse g-C3N4(CN) in waterborne epoxy resin (WEP, 0704), stir for 30 min and then sonicate for 30 min. Then add curing agent (CA, 0705) and stir until uniform to obtain coating. Among them, g-C3N4 is 2 wt% of the sum of waterborne epoxy resin and curing agent (CA). By volume, the ratio of waterborne epoxy resin to curing agent is 5:1.

[0071] Step 2: Apply the coating to the surface of Q235 carbon steel using a fully CNC small coating machine (FA-202D), dry at room temperature for 24 hours, and cure at 80℃ for 8 hours to obtain an anti-corrosion coating with a thickness of 100±10μm on the surface of Q235 carbon steel.

[0072] A method for preparing a hydrophobically modified anti-corrosion coating (CN / HWEP) is basically the same as the method for preparing a hydrophobically modified anti-corrosion coating in Example 1, except that the anti-corrosion coating in Example 1 is replaced with the anti-corrosion coating (CN / WEP) prepared in this example.

[0073] Example 5

[0074] A method for preparing an anti-corrosion coating (ECN / WEP) includes the following steps:

[0075] Step 1: Etch g-C3N4 in concentrated nitric acid to obtain the first precipitate:

[0076] 1. Repeat the following steps 8 times: Place g-C3N4 in concentrated nitric acid and stir at 70°C for 1 hour, then sonicate in a water bath at 70°C for 1 hour;

[0077] 2. Let stand for 24 hours, then centrifuge to obtain the first precipitate;

[0078] The first precipitate was sonicated in anhydrous ethanol for 8 hours (in a 70°C water bath) to obtain ECN;

[0079] Step 2: Disperse ECN in waterborne epoxy resin (WEP, 0704), stir for 30 min and then sonicate for 30 min. Then add curing agent (CA, 0705) and stir until uniform to obtain coating. The ECN is 2 wt% of the sum of waterborne epoxy resin and curing agent (CA) by mass, and the ratio of waterborne epoxy resin to curing agent is 5:1 by volume.

[0080] Step 3: Apply the coating to the surface of Q235 carbon steel using a fully CNC small coating machine (FA-202D), dry at room temperature for 24 hours, and cure at 80℃ for 8 hours to obtain an anti-corrosion coating (ECN / WEP) with a thickness of 100±10μm on the surface of Q235 carbon steel.

[0081] A method for preparing a hydrophobically modified anti-corrosion coating (ECN / HWEP) is basically the same as the method for preparing a hydrophobically modified anti-corrosion coating in Example 1, except that the anti-corrosion coating in Example 1 is replaced with the anti-corrosion coating (ECN / WEP) prepared in this example.

[0082] Example 6

[0083] A method for preparing an anti-corrosion coating (PANI / WEP) includes the following steps:

[0084] Step 1: Mix 16 mL of aniline (ANI) and deionized water in a beaker. First, add 100 mL of 5 M nitric acid (HNO3), then add 1 M nitric acid (HNO3) to adjust the pH and stir until homogeneous. Make up to 300 mL to obtain a liquid with pH 2 as solution A. Transfer solution A into a quartz test tube and place the quartz test tube containing solution A into a photochemical reactor (XPA-7 from Nanjing Xujiang Electromechanical Plant) for photopolymerization (photopolymerization temperature is 25℃, time is 6 h). After the photopolymerization reaction is completed, centrifuge to obtain the third precipitate. Wash the third precipitate with deionized water and freeze-dry to obtain polyaniline nanomaterial PANI. The high-pressure mercury lamp in the photochemical reactor has a power of 500 W, and the surface of the quartz test tube is fixed at a distance of 12 cm from the high-pressure mercury lamp.

[0085] Step 2: Disperse the polyaniline nanomaterial PANI in the aqueous epoxy resin (WEP, 0704), stir for 30 min and then sonicate for 30 min. Then add the curing agent (CA, 0705) and stir until uniform to obtain the coating. The polyaniline nanomaterial PANI is 3 wt% of the sum of the aqueous epoxy resin and the curing agent (CA). The ratio of the aqueous epoxy resin to the curing agent is 5:1 by volume.

[0086] Step 3: Apply the coating to the surface of Q235 carbon steel using a fully CNC small coating machine (FA-202D), dry at room temperature for 24 hours, and cure at 80℃ for 8 hours to obtain an anti-corrosion coating (PANI / WEP) with a thickness of 100±10μm on the surface of Q235 carbon steel.

[0087] A method for preparing a hydrophobically modified anti-corrosion coating (PANI / HWEP) is basically the same as the method for preparing a hydrophobically modified anti-corrosion coating in Example 1, except that the anti-corrosion coating in Example 1 is replaced with the anti-corrosion coating (PANI / WEP) prepared in this example.

[0088] Example 7

[0089] A method for preparing a corrosion-resistant coating (WEP) includes the following steps:

[0090] Step 1: Mix waterborne epoxy resin (WEP) and curing agent (CA) and stir thoroughly until homogeneous to obtain a coating. The ratio of waterborne epoxy resin (WEP) to curing agent (CA) by volume is 5:1.

[0091] Step 2: Apply the coating to the surface of Q235 carbon steel using a fully CNC small coating machine (FA-202D), dry at room temperature for 24 hours, and cure at 80℃ for 8 hours to obtain a 100±10μm thick anti-corrosion coating (WEP) on the surface of Q235 carbon steel.

[0092] A method for preparing a hydrophobically modified anti-corrosion coating (HWEP) is basically the same as the method for preparing a hydrophobically modified anti-corrosion coating in Example 1, except that the anti-corrosion coating in Example 1 is replaced with the anti-corrosion coating (WEP) prepared in this example.

[0093] Figure 1 'a' is a scanning electron microscope image of CN. Figure 1 b is a scanning electron microscope image of the ECN. (From...) Figure 1 a and Figure 1 As can be seen from b, CN is blocky, while ECN is porous sheet-like.

[0094] The nanomaterials were left to stand in WEP for 7 days. The ratio of nanomaterials to WEP by mass was 1:19. The nanomaterials were one of CN, ECN, PANI (purchased from Aladdin), the polyaniline nanomaterial PANI prepared in Example 6, and the polyaniline composite nanomaterial ECN@PANI prepared in Example 2. Figure 2 The images shown are, in order, digital photographs of CN, ECN, PANI (purchased from Aladdin), the polyaniline nanomaterial PANI prepared in Example 6, and the polyaniline composite nanomaterial ECN@PANI prepared in Example 2, after standing in WEP for 7 days. It can be seen that CN and PANI (purchased from Aladdin) exhibit extremely poor dispersion stability in WEP, with significant precipitation at the bottom of the bottle. In contrast, the dispersion stability of PANI prepared in Example 6 is significantly improved compared to PANI (purchased from Aladdin), with only a small amount of precipitation at the bottom of the bottle. Furthermore, ECN and the polyaniline composite nanomaterial ECN@PANI prepared in Example 2 show no significant precipitation at the bottom of the bottle, indicating that the polyaniline composite nanomaterials prepared by ECN and Example 2 have excellent dispersion stability.

[0095] The following electrochemical impedance spectroscopy (EIS) measurements were performed using a CHI660E electrochemical workstation, with an EIS measurement area of ​​4 cm². 2 The results were analyzed using ZView software. Three samples were prepared for each coating, and three EIS data were measured for each coating. The average value of the EIS data was taken as the coating fitting value, and the corresponding Nyquist / Bode plot was obtained based on the coating fitting value.

[0096] The coating was immersed in a 3.5 wt% NaCl aqueous solution for 1 day and then subjected to electrochemical impedance spectroscopy (EIS) testing. The coating was one of the anti-corrosion coatings prepared in Examples 1-3, the anti-corrosion coating CN / WEP prepared in Example 4, the anti-corrosion coating ECN / WEP prepared in Example 5, the anti-corrosion coating PANI / WEP prepared in Example 6, and the anti-corrosion coating WEP prepared in Example 7. The corresponding Nyquist plots are shown below. Figure 3 As shown in the figure. Generally, the changes in phase angle, impedance modulus, and capacitive arc of the coating at low frequencies can represent the corrosion resistance of the coating. The Nyquist plot shows that the larger the capacitive loop radius, the better the corrosion resistance. Therefore, it can be seen that the anti-corrosion coating prepared in Example 2 has the best corrosion resistance.

[0097] The coating was immersed in a 3.5 wt% NaCl aqueous solution for 1 day and then subjected to electrochemical impedance spectroscopy (EIS) testing. The coating was one of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7. The corresponding Nyquist plots are shown below. Figure 4 As shown. With Figure 3 In comparison, the anti-corrosion performance of the hydrophobically modified coatings in each embodiment was significantly improved.

[0098] The left vertical axis of the Bode plot represents the impedance |Z|, and the right vertical axis represents the phase angle. On the horizontal axis, the impedance |Z| corresponding to 0.01 Hz is the impedance modulus (|Z|). 0.01Hz The frequency corresponding to the inflection point of the phase angle curve is called the frequency F of the maximum phase angle. m , |Z| 0.01H z and F m It can be used to evaluate corrosion resistance. |Z| 0.01Hz The larger the size, the better the anti-corrosion effect. m The lower the value, the better its corrosion resistance, meaning it exhibits a phase angle close to -90° over the widest frequency range. m A value greater than 1 indicates that there are multiple defects on the surface of the hydrophobic modified anti-corrosion coating.

[0099] The coating was immersed in a 3.5 wt% NaCl aqueous solution for 1 day and then subjected to electrochemical impedance spectroscopy (EIS) testing. The coating was one of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7. The corresponding Bode plots are shown below. Figure 5 As shown. By Figure 5 It can be seen that |Z| of ECN@PANI / HWEP-2 0.01Hz It is two orders of magnitude higher than HWEP, and one order of magnitude higher than ECN / HWEP and PANI / HWEP. ECN@PANI / HWEP-2 exhibits the lowest F... m HWEP showed the highest F m This indicates that ECN@PANI / HWEP-2 has the best corrosion resistance.

[0100] The coating was immersed in a 3.5 wt% NaCl aqueous solution for 90 days and then subjected to electrochemical impedance spectroscopy (EIS). The coating was one of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7. The corresponding Nyquist plots are shown below. Figure 6 As shown.

[0101] The hydrophobic modified anticorrosive coatings prepared in Example 2, Example 6, Example 5, and Example 7 were subjected to UV (CEL-HXF300-T3) irradiation for 100 h, followed by electrochemical impedance spectroscopy (EIS) testing. The corresponding Nyquist plots are shown below. Figure 8 As shown.

[0102] The coatings were immersed in a 3.5 wt% NaCl aqueous solution for 90 days and then subjected to electrochemical impedance spectroscopy (EIS) testing. The coatings were one of the hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7. The corresponding Bode plots were obtained, and the impedance modulus (|Z|) was obtained from the Bode plots. 0.01Hz ) and the frequency F where the maximum phase angle is located m like Figure 7 As shown.

[0103] The hydrophobic modified anticorrosive coatings HWEP (prepared in Example 7), ECN / HWEP (prepared in Example 5), PANI / HWEP (prepared in Example 6), and 2 (prepared in Example 2) were subjected to UV radiation (CEL-HXF300-T3) for 100 h, followed by electrochemical impedance spectroscopy (EIS) to obtain the corresponding Bode plots. The impedance modulus (|Z|) was obtained from the Bode plots. 0.01Hz ) and the frequency F where the maximum phase angle is located m like Figure 9 As shown.

[0104] The hydrophobic modified anticorrosive coatings prepared in Examples 1-3, the hydrophobic modified anticorrosive coating PANI / HWEP prepared in Example 6, the hydrophobic modified anticorrosive coating ECN / HWEP prepared in Example 5, and the hydrophobic modified anticorrosive coating HWEP prepared in Example 7 were subjected to salt spray tests. Digital photographs of the salt spray tests after 30 days are shown below. Figure 10 As shown, Figure 10 A through F are, in order, hydrophobic modified anti-corrosion coatings HWEP, ECN / HWEP, PANI / HWEP, ECN@PANI / HWEP-1, ECN@PANI / HWEP-2, and ECN@PANI / HWEP-3. The salt spray test conditions were as follows: samples with "I"-shaped scratches were exposed to a salt spray test chamber (using a 5 wt% NaCl aqueous solution, pH = 7) at room temperature for accelerated corrosion testing. The samples were one of the hydrophobic modified anti-corrosion coatings prepared in Examples 1-3, PANI / HWEP prepared in Example 6, ECN / HWEP prepared in Example 5, and HWEP prepared in Example 7.

[0105] The hydrophobic modified anticorrosive coatings HWEP (prepared in Example 7), ECN / HWEP (prepared in Example 5), PANI / HWEP (prepared in Example 6), and 2 (prepared in Example 2) were subjected to ultraviolet (UV) irradiation for 100 hours. The water contact angles were measured before and after UV irradiation. Figure 11 As shown. The WCA (water contact angle) values ​​of the hydrophobic modified anti-corrosion coating surface before and after UV irradiation are as follows. Figure 11 As shown. Before UV irradiation, all hydrophobic modified anticorrosive coatings exhibited high hydrophobicity (>118°), indicating a good barrier effect against corrosive substances. After 100 hours of UV irradiation, the hydrophobic modified anticorrosive coatings prepared in Example 2 still maintained high WCA. HWEP showed the largest decrease in WCA (from 118.3° to 96.6°), while ECN@PANI / HWEP-2 showed a slight decrease in WCA (from 137.4° to 132.3°). This indicates that the hydrophobic modified anticorrosive coatings prepared in Example 2 possess excellent hydrophobic properties.

[0106] The hydrophobic modified anti-corrosion coating HWEP prepared in Example 7 was used. Figure 12 a) The hydrophobic modified anti-corrosion coating ECN / HWEP prepared in Example 5 Figure 12 (b) The hydrophobic modified anti-corrosion coating PANI / HWEP prepared in Example 6 Figure 12 c) and the hydrophobic modified anti-corrosion coating prepared in Example 2 ( Figure 12 d) The Chlorella culture medium (the Chlorella culture medium was obtained by diluting the Chlorella stock solution purchased from Xinzhongbang Veterinary Drug Official Flagship Store with water from Panhu Lake of Tianjin University of Technology, with a dilution factor of 10) was left to stand for 14 days. The FESEM images after 14 days are as follows: Figure 12 As shown. Figure 12The image shows a large amount of Chlorella covering the surface of the hydrophobic modified anti-corrosion coating HWEP. Figure 12 Figures b and c show that with the addition of ECN and PANI, the number of Chlorella adhering to the surfaces of the hydrophobic modified anticorrosive coatings ECN / HWEP and PANI / HWEP gradually decreased. It is noteworthy that... Figure 12 The d-value shows that the addition of the polyaniline composite nanomaterial ECN@PANI further reduced the adhesion of Chlorella to the hydrophobic modified anticorrosive coating prepared in Example 2, indicating that the polyaniline composite nanomaterial ECN@PANI can effectively inhibit algae adhesion. The hydrophobic modified anticorrosive coating prepared in Example 2 showed the best anti-algae performance.

[0107] The hydrophobic modified anticorrosive coating prepared in Example 2, after being immersed in a 3.5 wt% NaCl aqueous solution for 1 day, exhibited an impedance modulus of 5.2 × 10⁻⁶. 9 Ohm cm 2 The impedance modulus after soaking in a 3.5 wt% NaCl aqueous solution for 90 days is 1.5 × 10⁻⁶. 9 Ohmcm 2 The impedance modulus of the hydrophobic modified anticorrosion coating prepared in Example 2 after 100 hours of UV irradiation was 3.7*10. 9 Ohmcm 2 The hydrophobic modified anticorrosive coating prepared in Example 2 showed only a small amount of rust spots after 30 days of salt spray testing. No obvious Chlorella was observed in the FESEM image of the hydrophobic modified anticorrosive coating prepared in Example 2 after immersion in Chlorella culture medium for 14 days. The water contact angle of the hydrophobic modified anticorrosive coating prepared in Example 2 before ultraviolet radiation was 138°.

[0108] This invention prepares covalently crosslinked carbon nitride-polyaniline nanocomposite materials (polyaniline composite nanomaterial ECN@PANI) through photopolymerization. Compared with other methods (CN 115926522 A), the polyaniline composite nanomaterial ECN@PANI of this invention is covalently bonded, which is more stable than simple blending, has better performance and longer-lasting effect.

[0109] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a coating, characterized in that, Includes the following steps: Step 1: Etch g-C3N4 in an acidic solution to obtain a first precipitate, and sonicate the first precipitate to obtain etched g-C3N4; Step 2: Mix the etched g-C3N4, aniline, and water, adjust the pH, and stir until homogeneous to obtain a liquid with a pH of 1-4 as a polyaniline precursor solution. Incubate the polyaniline precursor solution at 10-40 °C for 4-8 h using photopolymerization. Centrifuge to obtain a second precipitate. Wash the second precipitate and dry it to obtain the polyaniline composite nanomaterial ECN@PANI. The ratio of the mass fraction of the etched g-C3N4, the volume fraction of aniline, and the volume fraction of the polyaniline precursor solution is 0.08:(10-20):

300. The mass fraction is in g, and the volume fraction is in mL. Step 3: Disperse the polyaniline composite nanomaterial ECN@PANI in waterborne epoxy resin, stir and then sonicate to obtain a first solution. Mix the first solution with a curing agent and stir until uniform to obtain a coating. The polyaniline composite nanomaterial ECN@PANI is 1-3 wt% of the sum of waterborne epoxy resin and curing agent. By volume, the ratio of waterborne epoxy resin to curing agent is (1-6):

1. The curing agent is used to cure the waterborne epoxy resin.

2. The preparation method according to claim 1, characterized in that, In step 2, the photopolymerization reaction is carried out using a mercury lamp with a power of 300~500 W.

3. The coating obtained by the preparation method as described in claim 1 or 2.

4. A method for preparing an anti-corrosion coating, characterized in that, include: The coating described in claim 3 is applied to the surface by scraping, dried, and cured to obtain an anti-corrosion coating on the surface.

5. The anti-corrosion coating obtained by the preparation method described in claim 4.

6. A method for preparing a hydrophobically modified anti-corrosion coating, characterized in that, include: The anti-corrosion coating of claim 5 is immersed in a homogeneous PDMS solution for 0.5 to 1.5 h, allowed to stand to allow the n-hexane to evaporate, and cured at 60 to 80 °C for 5 to 10 h to obtain a hydrophobic modified anti-corrosion coating, wherein the homogeneous PDMS solution is a mixture of PDMS bicomponent and n-hexane.

7. The method according to claim 6, characterized in that, In the method for preparing hydrophobic modified anti-corrosion coatings, the settling temperature is room temperature and the settling time is 12~48 h.

8. The method according to claim 6, characterized in that, The ratio of the PDMS bicomponent to n-hexane by volume is (1~5):

100.

9. The hydrophobic modified anti-corrosion coating obtained by the method described in claim 6.

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