Anticorrosive dispersion and preparation method thereof

Abstract

The present invention discloses an anti-corrosion dispersion and a preparation method thereof. The components of the anti-corrosion dispersion include: cerium oxide, sodium hexametaphosphate and 2DPA; the structural formula of the 2DPA is as follows: #imgabs0# The cerium oxide nanoparticles in the components of the anti-corrosion dispersion of the present invention can form a dense and smooth oxide film on the surface of the aluminum foil, which serves as a passivation layer, increases the corrosion potential, and inhibits the occurrence of corrosion. 2DPA has a two-dimensional planar structure similar to graphene and has excellent barrier properties, which prevents the penetration of corrosive media and protects the aluminum foil from being corroded by HF. In addition, after multi-layer stacking of 2DPA, due to the presence of amide covalent bonds within the molecular plane, strong hydrogen bonds can be formed between the planes, thereby improving the chemical stability of the molecules. At the same time, when multiple layers of 2DPA are stacked, a "maze effect" will occur to further improve its barrier ability, making it more difficult for HF to penetrate, thereby protecting the aluminum foil. Sodium hexametaphosphate is added to the anti-corrosion dispersion to ensure dispersion stability and reduce agglomeration.

Description

Technical Field

[0001] The present invention relates to the field of surface corrosion protection, and in particular to an anti-corrosion dispersion and a preparation method thereof. Background Art

[0002] Nano-CeO2 has excellent corrosion protection properties, forming a dense, smooth oxide passivation film that acts as a corrosion barrier. Furthermore, CeO2 is environmentally friendly, making it a promising material for chromium-free corrosion protection systems. However, due to their high surface energy, nanoparticles are prone to agglomeration, resulting in uneven particle size distribution, which undoubtedly affects their performance. Therefore, improving nanoparticle stability and preventing agglomeration are crucial during synthesis and subsequent dispersion preparation. Summary of the Invention

[0003] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides an anti-corrosion dispersion and a preparation method thereof.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] The first aspect of the present invention provides an anti-corrosion dispersion, wherein the components of the anti-corrosion dispersion include: cerium oxide, sodium hexametaphosphate and 2DPA; the structural formula of the 2DPA is as follows:

[0006]

[0007] In the field of polishing fluids, sodium hexametaphosphate is often added to CeO2 suspensions to ensure dispersion stability and reduce agglomeration. Based on this, the present invention adds an appropriate amount of sodium hexametaphosphate to the prepared nano-CeO2 dispersion to improve stability. Sodium hexametaphosphate can increase the negative charge of the nano-CeO2, increasing electrostatic repulsion and stabilizing the system.

[0008] Preferably, the components of the anti-corrosion dispersion include, by mass percentage, 1-4 wt% of cerium oxide, 0.05-0.2 wt% of sodium hexametaphosphate, and 0.2-0.3 wt% of 2DPA.

[0009] Preferably, the particle size of the cerium oxide is 18-23 nm.

[0010] Preferably, the preparation method of 2DPA comprises the following steps:

[0011] Melamine, 1,3,5-benzenetricarboxylic acid chloride, N-methyl-2-pyrrolidone and pyridine are mixed and stirred at room temperature to obtain a gel. The gel is immersed in an alcohol solution to obtain a mixture, which is filtered or centrifuged, washed and dried to obtain the 2DPA.

[0012] More preferably, in the method for preparing 2DPA, stirring is performed at room temperature for 12-20 h; still more preferably, in the method for preparing 2DPA, stirring is performed at room temperature for 15-17 h.

[0013] Further preferably, in the preparation method of 2DPA, the molar mass ratio of melamine to 1,3,5-benzenetricarboxylic acid chloride is 1:(0.8-1.2).

[0014] The second aspect of the present invention provides a method for preparing the antiseptic dispersion, comprising the following steps:

[0015] (1) dissolving cerium oxide and sodium hexametaphosphate in water and dispersing by ultrasonication to obtain a cerium oxide dispersion; dissolving 2DPA in dimethyl sulfoxide to obtain a 2DPA solution;

[0016] (2) Mixing the cerium oxide dispersion and the 2DPA solution to obtain the anti-corrosion dispersion.

[0017] Preferably, in step (1), probe ultrasonic treatment is performed for 20-40 minutes under ice bath conditions to obtain a cerium oxide dispersion.

[0018] Preferably, in step (1), the concentration of the 2DPA solution is 0.4-0.6 wt %.

[0019] The third aspect of the present invention provides the use of the anti-corrosion dispersion in the anti-corrosion of aluminum surfaces.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The cerium oxide nanoparticles in the anti-corrosion dispersion components of the present invention can form a dense, smooth oxide film on the surface of the aluminum foil, which acts as a passivation layer to increase the corrosion potential and inhibit the occurrence of corrosion. 2DPA has a two-dimensional planar structure similar to graphene and has excellent barrier properties, preventing the penetration of corrosive media and protecting the aluminum foil from HF corrosion. In addition, after multi-layer stacking of 2DPA, due to the presence of amide covalent bonds within the molecular plane, strong hydrogen bonds can be formed between the planes, thereby improving the chemical stability of the molecules. At the same time, when multiple layers of 2DPA are stacked, a "maze effect" will occur to further improve its barrier ability, making it more difficult for HF to penetrate, thereby protecting the aluminum foil. Sodium hexametaphosphate is added to the anti-corrosion dispersion to ensure dispersion stability and reduce agglomeration. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the chemical structure diagram of 2DPA;

[0023] Figure 2 2DPA H NMR spectrum ( 1 H-NMR);

[0024] Figure 3 This is a 2DPA atomic force microscope test image;

[0025] Figure 4 Schematic diagram of the three-electrode system;

[0026] Figure 5 is the aluminum foil working electrode;

[0027] Figure 6 It is the principle of Tafel curve test;

[0028] Figure 7 is the Tafel polarization curve;

[0029] Figure 8 is the Tafel polarization curve;

[0030] Figure 9 The SEM images of aluminum foil spin-coated with different anti-corrosion dispersions before and after HF corrosion;

[0031] Figure 10 Schematic diagram of the anti-corrosion passivation protection mechanism. DETAILED DESCRIPTION

[0032] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0033] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0034] Example 1

[0035] This embodiment provides a method for preparing an anticorrosive dispersion, which specifically includes the following steps:

[0036] (1) Weigh (NaPO3)6 at a CeO2 / (NaPO3)6 molar ratio of 20:1 and add it to the nano-CeO2 dispersion;

[0037] (2) The nano-dispersion after adding (NaPO3)6 was subjected to probe ultrasonic treatment for 30 min (1500W, 15s on, 15s off) under ice bath protection to obtain CeO2 anti-corrosion dispersion;

[0038] (3) Weigh 0.0275 g of 2DPA and 5.3150 g of dimethyl sulfoxide (DMSO), and stir for 30 minutes to dissolve 2DPA to obtain a 0.51 wt% 2DPA solution.

[0039] (4) The 2DPA solution and the CeO2 anti-corrosion dispersion are mixed to obtain an anti-corrosion dispersion, wherein the CeO2 content in the anti-corrosion dispersion is 1.1 wt % and the 2DPA content is 0.255 wt %.

[0040] The chemical structure of 2DPA is shown in the attached figure. Figure 1 As shown, 2DPA was prepared by the following method:

[0041] To a 40 mL vial equipped with a stir bar, 126 mg of melamine (1 mmol, 1 eq) and 265 mg of 1,3,5-benzenetricarboxylic acid chloride (1 mmol, 1 eq) were added, followed by 9 mL of n-methyl-2-pyrrolidone and 1 mL of pyridine. After stirring at room temperature (20-25°C) for 16 h, the reaction mixture turned into a gel. The gel was cut into small pieces and soaked in 80 mL of ethanol, followed by sonication for 30 minutes. The resulting turbid mixture was further filtered or centrifuged, washed with 80 mL of deionized water and 80 mL of acetone, and dried in vacuo at 100°C for 16 h to yield a light yellow powder (228 mg, 81%).

[0042] The chemical structure of the prepared 2DPA was tested by using deuterated dimethyl sulfoxide (DMSO-d6) as solvent and TMS as internal standard. The nuclear magnetic hydrogen spectrum ( 1 H-NMR), the results are as attached Figure 2 As shown, in the hydrogen nuclear magnetic resonance spectrum of 2DPA, a signal peak appears at 8.6 pmm, indicating the presence of phenyl hydrogen adjacent to the amide bond in the molecular structure of the target product; a signal peak with an integrated area of ​​1 appears at 6.95 pmm, proving that the structure contains an aromatic amide bond; a series of signal peaks at 1.2-1.4 ppm are peaks generated by the methyl group in the terminal group when ethanol is used to cap the end of the synthesis reaction; the signal peak generated at 4.4 ppm is also the peak of the methylene group in the ester group generated during the capping process; and the signal peak at 2.08 ppm is the signal peak generated by N-methylpyrrolidone (NMP), the solvent used in the synthesis. Taken together, the structure shown in the figure is obtained, and there are also impurity peaks left on the terminal group due to ethanol capping.

[0043] The prepared 2DPA was characterized by atomic force microscopy (AFM): a very dilute 2DPA solution (0.1 wt%) was prepared and spin-coated on a fluoromorphic mica sheet to form a 2DPA film. The Tapping Mode was selected and the needle model was ScanAsyst air for testing. The 2DPA atomic force microscopy test results are shown in Figure 2. Figure 3 The right picture is a cross-sectional view of the position indicated by the white line in the left picture. It can be seen that the 2DPA film in this position is about 10nm long and about (i.e. 0.3nm), which is the thickness of the monomer size, realizes the polymerization of two-dimensional polymers and obtains 2DPA two-dimensional materials.

[0044] Tafel polarization curve test

[0045] (1) Spin coating the passivation solution: Take a 5cm×5cm aluminum foil and treat it with plasma cleaning technology for 10 minutes. Immediately place the treated aluminum foil in a coater and evenly drop an appropriate amount of anti-corrosion dispersion on the surface of the aluminum foil. Set the program to 500rpm for 30 seconds and start the coater to complete the spin coating. Place the spin-coated aluminum foil in an oven at 60℃ and dry it for 2 hours.

[0046] (2) Electrode production: Cut the dried aluminum foil into 3.5 cm × 1 cm rectangles and stick the cut aluminum foil to a PVC plastic plate of appropriate size, leaving only the side where the passivation solution was spin-coated exposed. Figure 5 The electrodes shown are used for corrosion current testing;

[0047] (3) Preparation of electrolyte: prepare 100 ml of 100 ppm HF aqueous solution;

[0048] (4) Build a three-electrode system with an Ag / AgCl electrode as the reference electrode, a graphite electrode as the auxiliary electrode, and aluminum foil as the working electrode. Insert the electrodes into the electrolyte and connect them to the corresponding ports of the electrochemical workstation.

[0049] (5) Select the Tafel plot test program, then set the starting and ending potentials, the potential change rate to 0.001 V / s, and start the test;

[0050] (6) Prepare three samples of each passivation solution and perform three repeated tests.

[0051] The Tafel curve test principle is as follows Figure 6 The Tafel polarization curve results are shown as Figure 7-8 As shown, the ac figure is three repeated experiments, Figure 7In the figure, Ce is a spin-coated sample of a CeO2 dispersion with a solid content of 2.21%; Ce+2DPA(1) is a spin-coated sample of a mixture of CeO2 and 2DPA; Ce+2DPA(2) is a sample coated with CeO2 and then coated with 2DPA (the solvent is DMSO, the concentration is 0.51wt%), and Al is an uncoated aluminum foil.

[0052] The corresponding corrosion potential results in the Tafel polarization curve are shown in Table 1 below.

[0053] Table 1

[0054]

[0055]

[0056] According to the Tafel polarization curve, the corrosion potential of the material can be measured. The more positive the corrosion potential of the material, the better its corrosion resistance. Figure 7 As shown in Table 1, the corrosion potential of aluminum foil treated with CeO2 anti-corrosion dispersion increases, and its ability to resist HF corrosion is enhanced. This may be related to the fact that the smooth and dense oxide film formed by nano-CeO2 on the surface of aluminum foil can resist HF corrosion. At the same time, the aluminum foil coated with 2DPA also shows improved corrosion resistance, which is due to the high barrier property of 2DPA, which blocks the penetration of corrosive media. From the results of the Ce+2DPA sample, it can be seen that when the two are coated on the aluminum foil at the same time, the corrosion potential is further improved. Among them, (1) the sample is a mixture of CeO2 anti-corrosion liquid and 2DPA solution dripped on the aluminum foil surface to complete the spin coating in one step; (2) the sample is first coated with CeO2, dried and then spin coated with 2DPA, that is, two-step spin coating. Overall, the performance of the composite anti-corrosion layer formed by the two methods is similar, but one-step spin coating is more convenient and more in line with actual production needs. Subsequently, the composite passivation layer was prepared by mixed spin coating and compared with other samples.

[0057] The composite anti-corrosion coating prepared by mixed spin coating was compared with a standard sample and a trivalent chromium passivation solution sample. The trivalent chromium passivation solution consists of water, Cr(NO3)3, phosphoric acid and a chelating agent, with a solid content of 6.56%. From the corrosion potential, it can be seen that the trivalent chromium passivation solution has the best effect. There is still a certain gap in the anti-corrosion performance between the composite anti-corrosion coating of CeO2+2DPA and the passivation layer obtained after treatment with the trivalent chromium passivation solution. However, the corrosion potential of the composite anti-corrosion coating is similar to that of the standard sample (water, sodium hexametaphosphate, CeO2, where the CeO2 content is 6.39wt%), and a chromium-free anti-corrosion composite passivation system with performance similar to that of the standard sample was successfully obtained.

[0058] Table 2

[0059] Ce+2DPA(1) Standard samples Cr 1 -1.162V -1.151V -1.031V 2 -1.144V -1.155V -1.002V 3 -1.145V -1.160V -0.989V average value -1.150V -1.155V -1.007V

[0060] SEM images of aluminum foil spin-coated with different anti-corrosion dispersions before and after HF corrosion are shown in Figure 2. Figure 9 As shown, (a) and (b) are spin-coated samples of a mixture of CeO2 and 2DPA (the anti-corrosion dispersion of Example 1), (c) and (d) are standard CeO2 samples, and (e) and (f) are experimentally synthesized CeO2 dispersions (solid content: 2.21%). The left-hand pictures ((a)(c)(e)) are samples corroded with 100ppm HF for 1 hour, and the right-hand pictures ((b)(d)(f)) are samples that have not been corroded. From the scanning electron microscope photos, it can be seen that in the uncorroded samples, CeO2 nanoparticles form a smooth, dense oxide film on the surface of the aluminum foil. However, when observing the aluminum foil sample after being corroded with 100ppm HF for 1 hour, it can be clearly seen that the film on its surface has cracked and fallen off to a certain extent. Combined with the changes before and after corrosion, it is speculated that the increase in the corrosion potential of the aluminum foil is closely related to this oxide film. When the oxide film exists, it can act as an anti-corrosion barrier to block the corrosive medium and protect the internal aluminum foil from being corroded, so that the aluminum foil shows an increase in corrosion potential.

[0061] Combining the results of Tafel polarization curve and SEM morphology analysis, it is speculated that the protection mechanism of the composite anti-corrosion passivation layer is mainly to block the corrosive medium and protect the aluminum foil. The specific functions of the coating material are as follows:

[0062] (1) CeO2 nanoparticles can form a dense and smooth oxide film on the surface of aluminum foil, which acts as a passivation layer, increases the corrosion potential, and inhibits the occurrence of corrosion.

[0063] (2) 2DPA has a two-dimensional planar structure similar to graphene, and has excellent barrier properties, preventing the penetration of corrosive media and protecting aluminum foil from HF corrosion. In addition, after 2DPA is stacked in multiple layers, due to the presence of amide covalent bonds in the molecular plane, strong hydrogen bonds can be formed between the planes, improving the chemical stability of the molecules. At the same time, the stacking of multiple layers of 2DPA will produce a "maze effect" to further improve its barrier ability, making HF more difficult to penetrate, thereby protecting the aluminum foil. The schematic diagram of the "maze effect" and oxide barrier mechanism is shown in Figure 10 shown.

[0064] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. An anti-corrosion dispersion, characterized in that: The components of the anti-corrosion dispersion include: 1-4 wt% of cerium oxide, 0.05-0.2 wt% of sodium hexametaphosphate, and 0.2-0.3 wt% of 2DPA; the structural formula of the 2DPA is as follows: The preparation method of the anticorrosive dispersion comprises the following steps: (1) dissolving cerium oxide and sodium hexametaphosphate in water and dispersing by ultrasonication to obtain a cerium oxide dispersion; dissolving 2DPA in dimethyl sulfoxide to obtain a 2DPA solution; (2) mixing the cerium oxide dispersion and the 2DPA solution to obtain the anti-corrosion dispersion; The particle size of the cerium oxide is 18-23 nm; The anti-corrosion dispersion is used in aluminum surface anti-corrosion.

2. The anti-corrosion dispersion according to claim 1, characterized in that The preparation method of the 2DPA comprises the following steps: Melamine, 1,3,5-benzenetricarboxylic acid chloride, N-methyl-2-pyrrolidone and pyridine are mixed and stirred at room temperature to obtain a gel. The gel is immersed in an alcohol solution to obtain a mixture, which is filtered or centrifuged, washed and dried to obtain the 2DPA.

3. The anti-corrosion dispersion according to claim 2, characterized in that In the preparation method of 2DPA, stirring is performed at room temperature for 12-20 hours.

4. The anti-corrosion dispersion according to claim 2, characterized in that In the preparation method of 2DPA, the molar mass ratio of melamine to 1,3,5-benzenetricarboxylic acid chloride is 1:(0.8-1.2).

5. A method for preparing the anticorrosive dispersion according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) dissolving cerium oxide and sodium hexametaphosphate in water and dispersing by ultrasonication to obtain a cerium oxide dispersion; dissolving 2DPA in dimethyl sulfoxide to obtain a 2DPA solution; (2) Mixing the cerium oxide dispersion and the 2DPA solution to obtain the anti-corrosion dispersion.

6. Use of the anti-corrosion dispersion according to any one of claims 1 to 4 in the anti-corrosion of aluminum surfaces.

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