Preparation method and application of anti-corrosion coating

Abstract

The invention discloses a preparation method and application of an anti-corrosion coating, and particularly relates to a preparation and application method for forming a stable super-hydrophilic coating on the surface of a solid by taking nano silicon dioxide as a main raw material and performing chemical modification and curing. The coating can reduce chemical corrosion caused by contact between chemical substances and the solid surface, and the hydrophilic layer reduces mechanical friction damage between particle substances and the solid surface. According to the method, the surfaces of solids such as metal are coated with a prefabricated anti-corrosion material through a sol-gel method, a cured super-hydrophilic coating makes contact with an aqueous solution, a hydration film can be formed, and the function of protecting high-speed fluid transmission equipment containing solid particles is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of chemical environmental protection technology, and relates to a problem of mechanical abrasion caused by violent movement of the interface between a solid and a suspension and solid interface corrosion caused by chemical substances, especially the high-speed transmission of a high-salt aqueous solution and a solution of suspended particles and the contact physical and chemical damage of pipelines, pump bodies, etc., and a method for preparing and using a coating that destroys chemical corrosion and mechanical abrasion on the solid surface. Technical Background

[0002] Solid alloys such as metals are widely used in the fields of transportation, aerospace, and materials. They are characterized by extremely high strength at room temperature, but their corrosion resistance is poor, especially in high-salt solutions. Calcium ions and chloride ions will collide with solid metals on the surface of the alloy, causing corrosion of solid metals.

[0003] In order to solve the problem of alloy corrosion, the sustained release ability of solid alloy surfaces such as metals is improved. For example, in the Chinese patent CN117802550A (An anticorrosive coating applied to aluminum alloy surface and its preparation method and application) by Xiao Lairong et al., a magnesium-rich epoxy resin layer is formed on the aluminum alloy surface by micro-oxidation to improve the anticorrosion ability, but this method increases the hydrophobicity of the material surface, resulting in an increased probability of salt ions colliding with the surface. In the authorized Chinese patent CN118422205B (A corrosion inhibitor for marine building steel structure and its preparation method), Sun Ziang et al. mentioned that two-component MOFs and zinc oxide form an anticorrosion layer on the surface of steel structure to improve the anti-penetration ability, but the MOF synthesis is complex, and the abundance of cerium and zirconium is low, so its promotion is limited. In the authorized Chinese patent CN115991899B (new anti-corrosion and anti-rust materials for high-alkali and high-salinity water equipment and their preparation methods), Tong Xin et al. found that adding phenolic or aldehyde sulfides to the coating material to form antioxidants effectively inhibits the oxidation of free radicals and improves the material's anti-corrosion properties, but the addition of excessive organic matter leads to an increase in the hydrophobicity of the coating surface.

[0004] The problem with the existing technology is that although polymer coatings and corrosion inhibitors can prevent chemical corrosion in the process of using pumps to transport suspended particles, abrasion caused by friction between particles is difficult to avoid, especially the base of the pump and the bends of the pipeline are often damaged by mechanical friction, resulting in fluid leakage. Summary of the invention

[0005] In order to solve the above-mentioned technical problems, the present invention utilizes stable materials such as inorganic silica to form a super hydrophilic layer on the fluid and solid surface, thereby reducing the contact between chemical substances and the solid surface, and preventing mechanical friction damage and chemical corrosion.

[0006] The present invention adopts the sol-gel method to coat the prefabricated anti-corrosion material on the solid surface of metal or the like, and adds a super-hydrophilic coating with a contact angle of less than 5° after stable solidification, which can reduce the collision between ions in the high-salt solution and the solid surface of metal or the like, thereby increasing the anti-corrosion performance. At the same time, the hydration layer formed by the super-hydrophilicity of the interface can avoid the friction between tiny solid particles and solids. Therefore, it can not only strengthen the protection against chemical corrosion, but also realize the multifunctionality of resistance to mechanical damage of high-speed fluid.

[0007] The steps adopted by the present invention to solve the technical problem are as follows:

[0008] (1) Inorganic stable silicon dioxide, sodium hydroxide, water and silane coupling agent are selected as raw materials and ground and mixed in a mechanical spheroidal graphite mill.

[0009] The powder size of silicon dioxide is 10-100 nm; the sodium hydroxide is industrial grade, and the pH is 12-14; the coupling agent is N-(2-aminoethyl)-3-aminopropyltriethoxysilane oligomer (AEAOS).

[0010] When spheroidal graphite is produced, the mass ratio of silica: water: coupling agent is 2:1:0.1-0.8.

[0011] (2) The mixed liquid in step (1) is transferred to a spherical ink kettle for thorough stirring and mixing. The slurry is removed from the spherical ink kettle and cooled to room temperature, sealed and aged for 12-20 hours, and the particle size distribution is tested to be 50-200 nm to obtain a gel, i.e., an anti-corrosion coating.

[0012] The gel is applied to the solid surface with the help of tools, and forms a stable coating after temperature curing. When in use, the contact surface is coated as needed, using tools such as spraying, brushing or pulling, with a thickness of 1-3 microns. In order to ensure a good effect, it can be applied three times, and after coating, it needs to be cured at 80-100℃ for 2-8 hours.

[0013] The beneficial effects of the present invention are:

[0014] This method uses the sol-gel method to coat prefabricated anti-corrosion materials on solid surfaces such as metals. The cured super-hydrophilic coating can form a hydration film when in contact with an aqueous solution, thereby achieving a protective function for high-speed fluid transmission equipment containing solid particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a process flow chart of the present invention;

[0016] Figure 2 The contact angle of the coating film with 10% AEAOS concentration;

[0017] Figure 3The cross-sectional diagram of the hydrophilic coating with different AEAOS concentrations;

[0018] Figure 4 (a) Nyquist plot and (b) polarization curve of superhydrophilic films with different AEAOS concentrations. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with implementation examples and drawings.

[0020] Example 1: Electrochemical testing of coatings

[0021] N-(2-aminoethyl)-3-aminopropyltriethoxysilane oligomer (AEAOS) was used as a silane coupling agent. 1%, 5%, 10%, 20% and 30% AEAOS were added to the nano-silica sol and synthesized by strong stirring at pH = 14. The reaction was carried out at 50°C for 3h, cooled to room temperature, and aged at room temperature for 24h. The modified nano-silica sol was coated on the aluminum alloy substrate at 1mm / s. The sample was cured in an oven at 120°C for 30 minutes. The final results are as follows:

[0022] Superhydrophilic coatings formed by 1%, 5%, 10%, 20% and 30% AEAOS modified nano-silica. Under conditions of low amino concentration, part of AEAOS was grafted to the nano-silica surface in the form of weak bonds, causing the contact angle to increase as the number of silanols decreased. However, as the amino concentration increased, the grafting density increased and the weak bond content decreased. Weak bond reduction released more silanol groups, increasing the polarity of the functional groups and causing the contact angle to decrease. The superhydrophilic film formed by 10% AEAOS was the best, with a contact angle of 2.8°. Figure 2 shown.

[0023] SEM was used to describe the surface state of the films with different AEAOS addition amounts, as shown in the attached figure. Figure 3 As shown. The coating formed by 1% AEAOS improves the hydrophilicity and adhesion of the original metal and other solid alloy surfaces. The amount of amino groups added is very small, and the modified nano-silica sol has undispersed clumps. As the amount of AEAOS added increases, the concentration of amino groups also increases. The bridging effect of excess AEAOS as a coupling agent allows the nano-silica particles to cross-link to form a complete three-dimensional network structure. When the concentration of AEAOS is 30%, the surface of the hydrophilic film becomes more dense.

[0024] Attached Figure 4a shows the Nyquist plot of an aluminum alloy sample coated with an AEAOS modified superhydrophilic film in a 5% CaCl2 solution. The results show that the surface of the aluminum alloy sample coated with the superhydrophilic coating has a larger capacitance arc than the blank aluminum alloy without the superhydrophilic coating, indicating that the superhydrophilic coating improves the corrosion resistance of the aluminum alloy sample. Since the coatings formed by 1% and 5% AEAOS have similar "grafting" effects of modified silica and coating density, the film resistance and the charge transfer resistance between the coating and the interface are similar. When the concentration of AEAOS added exceeds 20%, the capacitance arc radius decreases and the corrosion resistance gradually decreases. The structural regularity and density of the aminosilane oligomers decrease with the increase of the amino concentration, thereby reducing the corrosion resistance of the coating. The superhydrophilic coatings modified with 10% and 20% AEAOS have the best density and corrosion resistance.

[0025] Potentiodynamic polarization test results, as attached Figure 4 As shown in b. It can be seen that the corrosion potential increases with the increase of AEAOS concentration, indicating that the super hydrophilic coating on the surface plays a certain role in corrosion protection, but due to the low density of the formed coating, the increase in corrosion potential is relatively small. 1% AEAOS has the highest corrosion potential and the least possibility of corrosion. The weak hydrophilicity reduces the penetration of electrolyte into the coating surface to a certain extent, thus reducing the possibility of corrosion. Increasing the concentration of AEAOS, the corrosion potential moves negatively, and the corrosion current density first decreases and then increases. Among them, the corrosion current density of the 10% AEAOS modified super hydrophilic coating and the 20% AEAOS modified coating is the smallest, indicating that they have better corrosion resistance, which is consistent with the results of the electrochemical impedance spectroscopy.

[0026] Example 2: Testing using a 5% suspension in a pump

[0027] Use 20g of 20nm silica, add 10g of deionized water, add 6ml of 40% N-(2-aminoethyl)-3-aminopropyl triethoxysilane oligomer (AEAOS) solution, adjust the pH to 13.2 with sodium hydroxide solid under stirring, heat to 32°C, transfer to the spheroidal graphite kettle at 400rpm for 3 hours (spheroidal graphite to material ratio is 5:1), stop the spheroidal graphite, the inner dimension of the kettle is 67°C, remove to a 250ml wide-mouth bottle, wait to cool to room temperature, stir for 10 minutes, and age the wide-mouth bottle cap for 12 hours. The 125w pump base is the test sample, made of aluminum alloy, applied to the inner wall of the pipeline pump pump seat, brushed 3 times, and the brushing speed is 1mm / s. Move the pump seat into the oven and cure at 80°C for 2 hours.

[0028] The fluid solution was 5% powdered activated carbon slurry, and the particle size of the activated carbon powder was below 200 mesh. The pump power was 125w, the flow rate was 1.5 tons / h, and there was no fluid leakage after 30 days of continuous use. The control group without coating had multiple leakage points due to friction after 7 days.

Claims

1. A method for preparing an anti-corrosion coating, characterized in that: Inorganic stable silicon dioxide, sodium hydroxide, water and silane coupling agent are selected as raw materials, ground and mixed in a mechanical ductile iron machine in proportion; the mixed liquid is then removed to a container for sufficient stirring and mixing, and the gel, i.e., the anti-corrosion coating, is obtained by aging.

2. The method for preparing an anti-corrosion coating according to claim 1, characterized in that: The specific steps are as follows: 1) Select silicon dioxide, sodium hydroxide, water and silane coupling agent as raw materials, grind and mix them in a mechanical spheroidal graphite mill; The powder size of silicon dioxide is 10-100 nm; the sodium hydroxide is industrial grade, and the pH is 12-14; the coupling agent is N-(2-aminoethyl)-3-aminopropyltriethoxysilane oligomer (AEAOS); When spheroidal graphite is used, the mass ratio of silica: water: coupling agent is 2:1:0.1-0.8; (2) The mixed liquid in step (1) is transferred to a spherical ink kettle for thorough stirring and mixing, the slurry is removed from the spherical ink kettle and cooled to room temperature, sealed and aged for 12-20 hours, and the particle size distribution is tested to be 50-200 nm to obtain a gel, i.e., an anti-corrosion coating.

3. The gel prepared by the method for preparing an anti-corrosion coating according to claim 1, characterized in that: When in use, it is applied to the solid surface with the help of tools, and a stable coating is formed after temperature curing.

4. The use according to claim 3, characterized in that: When in use, the contact surface is coated as needed, using tools such as spraying, brushing or pulling.

5. The use according to claim 4, characterized in that: The thickness is 1-3 microns.

6. The use according to claim 4 or 5, characterized in that: Apply three times and then cure at 80-100℃ for 2-8 hours.

Images