Super-hydrophobic unit cell powder, preparation method and application thereof in preparation of composite anticorrosive coating

Abstract

The application discloses a kind of super-hydrophobic unit cell powder, which is composed of particles in unit cell structure; each unit cell particle has a shell of super-hydrophobic round diatomite, and the round diatomite has a hollow porous structure; the hollow cavity of the diatomite is filled with super-hydrophobic inorganic nanoparticles and corrosion inhibitor filled in the gap between the inorganic nanoparticles, and a membrane for sealing the pores of the diatomite shell is also provided. The application also discloses a preparation method of the super-hydrophobic unit cell powder and its application in preparing a composite anticorrosive coating. During the formation of the coating, the unit cell particles are connected to the resin through chemical cross-linking by the hydroxyl groups on the surface of the unit cell particles, and the unit cell particles are connected to the resin through chemical bonding, which can significantly improve the compatibility and bonding force of the unit cell particles and the resin. By increasing the spraying pressure during spraying, the vertical density of the coating is improved, and the coating has good mechanical strength and long-term corrosion resistance due to the synergistic effect of multiple factors.

Description

Technical Field

[0001] This invention relates to a superhydrophobic unit cell powder, and also to a method for preparing the superhydrophobic unit cell powder and its application in the preparation of composite anti-corrosion coatings. Background Technology

[0002] Corrosion is ubiquitous in daily life. Traditional anti-corrosion strategies include coatings, anti-corrosion metals (stainless steel, titanium alloys, and aluminum alloys, etc.), surface treatment, electrochemical protection, corrosion inhibitors, and rust-preventive oils / greases. Among these, coatings have become the mainstream anti-corrosion method due to their low cost, good protection, convenient maintenance, and the ability to obtain various special physical and chemical properties through filler modification. However, most current mainstream anti-corrosion coatings use zinc powder, mica powder, flake alumina, and silica powder as anti-corrosion fillers. These either use sacrificial anode Zn powder to protect the metal substrate or create a "maze effect" through physical barriers to prevent the diffusion of corrosive media within the coating. After decades of development, this type of method has reached a bottleneck, making significant performance breakthroughs unlikely.

[0003] Superhydrophobic surfaces, due to their unique surface wettability, can effectively resist three-phase water (gas, liquid, and solid) and dissolved substances such as Cl-. - Its ability to withstand corrosive media makes it valuable in the field of corrosion protection. However, due to the lack of active sites after hydrophobic modification, superhydrophobic particles can lead to problems such as poor compatibility with resins, weak bonding, and numerous coating defects (pores and microcracks, etc.), which limit their application as superhydrophobic fillers in anti-corrosion coatings. Summary of the Invention

[0004] Objective of this invention: This invention aims to provide a superhydrophobic unit cell powder, which is composed of particles with a unit cell structure. During the coating formation process, the unit cell particles are chemically cross-linked with the resin through excess hydroxyl groups on their surface. This chemical bonding between the unit cell particles and the resin significantly improves the compatibility and bonding strength between the unit cell particles and the resin. Furthermore, by increasing the spraying pressure during spraying, the longitudinal density of the coating is enhanced. The coating of this invention exhibits good mechanical strength and long-term corrosion resistance. Another objective of this invention is to provide a method for preparing the aforementioned superhydrophobic unit cell powder and its application in the preparation of composite anti-corrosion coatings.

[0005] Technical solution: The superhydrophobic unit cell powder of the present invention is composed of particles with a unit cell structure; each unit cell particle has a superhydrophobic spherical diatomaceous earth shell as the shell, and the spherical diatomaceous earth has a hollow porous structure; the hollow cavity of the diatomaceous earth is filled with superhydrophobic inorganic nanoparticles and corrosion inhibitors filled in the gaps between the inorganic nanoparticles, and a membrane for sealing the pores is also provided at the pore structure of the diatomaceous earth shell.

[0006] The unit cell particles have a particle size of 10–30 micrometers; the pore size of the diatomaceous earth shell has a pore size of 120–300 nm; and the inorganic nanoparticles have a particle size smaller than the pore size of the diatomaceous earth shell. The diatomaceous earth used in this invention was purchased from Nanyu Mining and obtained through screening.

[0007] Among them, the inorganic nanoparticles are silicon dioxide nanoparticles, aluminum oxide nanoparticles or titanium dioxide nanoparticles, and the particle size of the inorganic nanoparticles is 10-20 nm.

[0008] The preparation method of the above-mentioned superhydrophobic unit cell powder includes the following steps:

[0009] (1) Preparation of modified nanosol: In a constant temperature water bath, 4-5 parts ammonia water, 0.3-0.5 parts surfactant, 0.5-0.6 parts low surface energy substance and 5-8 parts nanosol were added to 80 parts deionized water and mixed evenly. After stirring and reaction, hydrophobic modified nanosol A was obtained.

[0010] (2) Preparation of coated diatomaceous earth particle suspension: By mass, 4-5 parts of ammonia water, 0.7-1.2 parts of aluminum hydroxide and 3-5 parts of micron-sized porous diatomaceous earth particles were added to 80 parts of deionized water and mixed evenly under constant temperature water bath. After reacting for 5-6 hours, 0.5-1 parts of silane coupling agent were added and the reaction was continued for another 5-6 hours to obtain coated (coated with aluminum hydroxide) diatomaceous earth particle suspension. After the diatomaceous earth particles were modified in the above way (diatomaceous earth modified with aluminum hydroxide surface), the strength of the diatomaceous earth particles can be effectively enhanced. On the other hand, the surface of the diatomaceous earth particles can be enriched with highly active hydroxyl groups (aluminum hydroxyl groups). The highly active hydroxyl groups make the diatomaceous earth particles superhydrophobic and can undergo chemical cross-linking reaction with resin.

[0011] (3) Preparation of superhydrophobic unit cell particles: Nanosol A and diatomaceous earth particle suspension were mixed and stirred in a constant temperature water bath for 12 hours to obtain unit cell particle suspension; corrosion inhibitor was added to unit cell particle suspension until a saturated corrosion inhibitor solution was formed; air in the pores of unit cell particles was removed by vacuuming, and the saturated corrosion inhibitor solution entered the cavity of unit cell particles to achieve corrosion inhibitor loading. This vacuuming was repeated more than 3 times to increase the corrosion inhibitor loading; finally, the unit cell particle suspension was dried at high temperature to obtain superhydrophobic unit cell powder.

[0012] In the process of mixing nanosol A and diatomaceous earth particle suspension, the mixing mass ratio of hydrophobically modified inorganic nanoparticles in nanosol A to modified diatomaceous earth particles in diatomaceous earth particle suspension is 3-3.5:10.

[0013] (4) The superhydrophobic unit cell particles are sealed and dried at high temperature to obtain sealed unit cell powder.

[0014] In step (1), the surfactant is at least one of NEO-4990, FS-3100, FS-61, or FS-30; the low surface energy substance is at least one of tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, or heptadecafluorodecyltriethoxysilane; the nanosol is one or more of silica nanosol, alumina nanosol, or titanium dioxide nanosol with a particle size of 10-20 nm, and the solid content of the nanosol is 15-25 wt.%.

[0015] In step (2), the silane coupling agent is at least one of KH550, KH560, KH570, KH580, and KH590. The specific selection depends on the combination of characteristic functional groups of the resin in the subsequent coating to ensure the chemical bonding reaction between the resin and the unit cell particles.

[0016] In step (3), the corrosion inhibitor is at least one of 2-mercaptobenzothiazole, benzotriazole, 2-mercaptobenzoimidazol, dodecylamine, 8-hydroxyquinoline or imidazole; or the corrosion inhibitor is at least one of chromate, phosphate or sulfate; the specific selection should be based on the type of substrate material to be protected in order to ensure good corrosion inhibition effect.

[0017] In step (3), the drying temperature is 120-180℃ and the drying time is 4-6h; the particle size of the superhydrophobic unit cell powder is 10-30μm and the drying method is either spray drying or oven drying.

[0018] In step (4), the specific sealing process is as follows: taking advantage of the negatively charged surface of the modified superhydrophobic unit cell, a suitable cationic polymer is selected, and the cationic polymer solution (2 mg / mL) and the unit cell particle suspension (50 mg / mL) are mixed at a volume ratio of 6:4. Under mechanical stirring at 300 r / 30 min, the mixture is electrostatically applied to the surface of the unit cell particles. After centrifugation at 8000 r / 3 min, excess cationic polymer is removed by washing with ethanol or water. After being covered by the cationic polymer, the unit cell particles are positively charged. Then, the anionic polymer solution (10 mg / mL) and the unit cell particle suspension (50 mg / mL) are mixed at a volume ratio of 6:4. Under mechanical stirring at 300 r / 30 min, the mixture is electrostatically applied to the surface of the unit cell particles. After centrifugation at 8000 r / 3 min, excess anionic polymer is removed by washing with ethanol or water. A composite film layer constructed by cationic polymer and anionic polymer is obtained on the surface of the pores of the unit cell particles, thus completing the sealing treatment of the superhydrophobic unit cell particles.

[0019] The cationic polymer is at least one of chitosan, polyethyleneimine, polystyrene, or polyacrylamide; the anionic polymer is at least one of sodium polystyrene sulfonate, polyacrylic acid, or polyacrylonitrile.

[0020] The application of the superhydrophobic unit cell powder in the preparation of composite anti-corrosion coating is as follows: at room temperature, 2.5 to 3 parts of superhydrophobic unit cell powder, 5 to 6 parts of resin and 15 to 18 parts of organic solvent are mixed and stirred, and then 1.5 to 2 parts of curing agent are added. After stirring evenly, the mixture is sprayed onto the surface of a substrate with a pre-cured epoxy coating. After curing at room temperature, a composite anti-corrosion coating is obtained.

[0021] The resin is a resin containing isohydroester groups, epoxy groups, carboxyl groups, amino groups, or unsaturated hydrocarbon functional groups.

[0022] The resin is polyurethane, epoxy resin, fluorocarbon resin or polyurea resin.

[0023] The organic solvent is at least one of butyl acetate, tetrahydrofuran, n-hexane, diethyl ether, benzene, or ketones.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0025] (1) This invention first strengthens the surface of natural porous diatomaceous earth with aluminum hydroxide to increase the hydroxyl content and hydroxyl activity on the surface of the diatomaceous earth shell, so that more hydrophobic long chains are grafted onto the diatomaceous earth shell in superhydrophobic modification while retaining more active hydroxyl sites, thus realizing the heterogeneous surface of the unit cell; and loads completely hydrophobic inorganic nanoparticles in the pores to further improve the overall hydrophobicity of the unit cell particles, thereby increasing the active hydroxyl sites while greatly improving the hardening and hydrophobicity of the unit cell particles.

[0026] (2) In this invention, a silane coupling agent is chemically bonded to the active hydroxyl sites retained on the surface of diatomaceous earth particles. During coating curing, the silane coupling agent acts as a connecting segment and chemically bonds with the characteristic active groups of the resin, thereby connecting the unit cell particles and the resin through chemical bonding. On the one hand, this improves the compatibility between the resin and the superhydrophobic unit cell particles and reduces defects such as pores and microcracks in the cured coating. On the other hand, it enhances the bonding force between the superhydrophobic unit cell particles and the resin and increases the degree of crosslinking of the coating. Combined with a suitable spraying process (increasing the spraying pressure during spraying), the composite anti-corrosion coating has superhydrophobicity on the surface and high density in the longitudinal direction, thus achieving good mechanical strength and corrosion resistance.

[0027] (3) This invention constructs an interlaced superhydrophobic unit cell network in the resin, which enables the coating to effectively increase the resistance to the diffusion of corrosive media and extend the penetration path. The hydrophobic nanoparticles loaded in the unit cell provide enhanced steric hindrance to corrosive media when the unit cell structure is not damaged. When the unit cell structure is damaged under large mechanical stress, the released corrosion inhibitor replenishes the hydrophobicity of the damaged area in real time, realizing hydrophobic self-repair. In addition, both the loaded nanoparticles and the sealing layer help the corrosion inhibitor to inhibit corrosion, forming a stimulus-response corrosion inhibitor release strategy, which enables the formation of a dense passivation film at the metal interface to prevent corrosion of the metal substrate for a long time.

[0028] (4) The composite anti-corrosion coating based on superhydrophobic unit cell powder has excellent resistance to the penetration of corrosive media in gas, liquid and solid water, ensuring the multiphase corrosion resistance of the anti-corrosion coating. Attached Figure Description

[0029] Figure 1 A shows the surface morphology, loading status, and elemental composition of the unit cell particles; B shows the SEM morphology of the unit cell particles; C shows the SEM microstructure of the hydrophobic nanoparticles loaded in the porous structure of the unit cell particles; D shows the cross-sectional TEM image of diatomaceous earth after surface modification with an aluminum hydroxide nanolayer; and D shows the elemental types and contents of the cross-section of the unit cell particles.

[0030] Figure 2Fourier transform infrared spectra of the modified nanoparticles, modified diatomaceous earth, unit cells, and composite coatings obtained in Comparative Example 1, Example 1, and Example 2.

[0031] Figure 3 X-ray photoelectron spectroscopy of unit cell particles in Example 1;

[0032] Figure 4 The unit cell particle hardness and elastic modulus of Comparative Example 1 and Example 1;

[0033] Figure 5 Hydrophobicity characterization of nanoparticles, diatomaceous earth, and unit cell particles in Example 1 and Comparative Example 1;

[0034] Figure 6 The microstructures of the front and cross-section of the hydrophobic and superhydrophobic composite anti-corrosion coatings of Example 2 and Comparative Example 2 are shown; surface morphology A and cross-sectional morphology B of the hydrophobic composite anti-corrosion coating; surface morphology C and cross-sectional morphology D of the superhydrophobic composite anti-corrosion coating.

[0035] Figure 7 The pore size distribution curves of the hydrophobic and superhydrophobic composite anti-corrosion coatings of Example 2 and Comparative Example 2 are shown.

[0036] Figure 8 The corrosion resistance and mechanical stability of the hydrophobic composite anti-corrosion coating in Example 2; A. Salt water immersion resistance; B. Salt erosion resistance; C. Abrasion resistance;

[0037] Figure 9 Electrochemical performance of the composite anti-corrosion coatings of Examples 2 and Comparative Examples 3-6 after immersion in 3.5 wt.% brine for 112 days; A. Low-frequency impedance; B. Polarization curve;

[0038] Figure 10 Microstructure of the hydrophobic composite anti-corrosion coating in Example 2 after 2500 hours of salt spray: A. Surface morphology; B. Cross-sectional morphology; C. Cross-sectional morphology of Cl element distribution.

[0039] Figure 11 The macroscopic corrosion morphology of the composite anti-corrosion coatings of Example 2 and Comparative Example 6 during 3000h salt spray corrosion is shown.

[0040] Figure 12 The adhesion variation of the composite anti-corrosion coatings in Example 3 and Comparative Example 7 during a 2000-hour salt spray corrosion test is shown.

[0041] Figure 13 The mass loss of the composite anti-corrosion coatings of Example 3 and Comparative Example 7 after wear in a 1kg / 1000r Taber abrasion test during a 2000h salt spray corrosion test;

[0042] Figure 14The results of the 0.4m ball impact test on the composite anti-corrosion coatings of Example 3 and Comparative Example 7 after 2500h salt spray corrosion are shown; gray represents the unit cell composite anti-corrosion coating; blue represents the bottom composite commercial anchor chain graphene anti-corrosion coating.

[0043] Figure 15 Macroscopic morphology of the composite anti-corrosion coatings of Example 3 and Comparative Example 7 after 2500h salt spray corrosion. Detailed Implementation

[0044] Example 1

[0045] The method for preparing superhydrophobic unit cell powder of the present invention includes the following steps:

[0046] (1) Preparation of modified nanosol: By mass, 4-5 parts of ammonia water (standard reagent AR), 0.3-0.5 parts of surfactant (FS-30), 0.5-0.6 parts of low surface energy substance (heptadecyltriethoxysilane), and 5-8 parts of nanosol (10-20 nm silica nanosol with a solid content of 15 wt.%) were added to 80 parts of deionized water and mixed evenly under a constant temperature water bath at 50℃. After stirring and reacting for 12 h, hydrophobic modified nanosol A was obtained.

[0047] (2) Preparation of diatomaceous earth particle suspension: By mass, 4-5 parts of ammonia water (standard reagent AR), 0.7-1.2 parts of aluminum hydroxide and 3-5 parts of porous diatomaceous earth particles with a particle size of 10-30 micrometers were added to 80 parts of deionized water and mixed evenly under a constant temperature water bath at 50℃. After reacting for 6 hours, 0.5-1 parts of silane coupling agent (KH550) were added and the reaction was continued for another 6 hours to obtain the diatomaceous earth particle suspension.

[0048] (3) Preparation of superhydrophobic unit cell powder: Nanosol A and diatomaceous earth particle suspension were mixed evenly, wherein the mass ratio of hydrophobically modified inorganic nanoparticles (10-20 nm silica nanosol, solid content of 1.6%) in nanosol A to modified diatomaceous earth particles in diatomaceous earth particle suspension was 3:10; the reaction was carried out under constant temperature water bath at 50℃ for 12 h to obtain unit cell particle suspension; corrosion inhibitor (benzotriazole) was added to unit cell particle suspension until a saturated corrosion inhibitor solution was formed; air in the pores of unit cell particles was removed by vacuuming, and the saturated corrosion inhibitor solution entered the cavity of unit cell particles to achieve corrosion inhibitor loading; the vacuuming was repeated more than 3 times to increase the corrosion inhibitor loading in unit cell particles; finally, the unit cell particle suspension was dried at high temperature (drying at 150℃ for 6 h) to obtain superhydrophobic unit cell powder.

[0049] (4) Sealing treatment of superhydrophobic unit cell particles: Chitosan solution with a concentration of 2 mg / mL was mixed with unit cell particle suspension (50 mg / mL) at a volume ratio of 6:4. The mixture was electrostatically coated onto the surface of the unit cell particles under mechanical stirring at 300 r / 30 min. After centrifugation at 8000 r / 3 min, excess cationic polymer was removed by washing with ethanol or water. After being coated with cationic polymer, the unit cell particles were positively charged. Then, polyacrylic acid solution with a concentration of 10 mg / mL was mixed with unit cell particle suspension (50 mg / mL) at a volume ratio of 6:4. The mixture was electrostatically coated onto the surface of the unit cell particles under mechanical stirring at 300 r / 30 min. After centrifugation at 8000 r / 3 min, excess anionic polymer was removed by washing with ethanol or water. A composite film layer constructed of cationic polymer and anionic polymer was obtained on the surface of the pores of the unit cell particles, completing the sealing treatment of the superhydrophobic unit cell particles. The particles were dried at 150 °C for 6 h to obtain sealed unit cell powder.

[0050] Figure 1 The surface morphology and elemental composition of unit cell particles, Figure 1 A shows that diatomaceous earth particles are round and contain natural hard particles with a rich porous structure. Figure 1 As can be seen from B, the design of the unit cell structure successfully loaded fully hydrophobic nanoparticles into the rich porous structure of diatomite, which can improve the hydrophobicity of the unit cell particles and realize the hydrophobic self-healing property in mechanical wear. Figure 1 As can be seen in Figure C, after surface modification with aluminum hydroxide, a thin film of aluminum hydroxide was generated in situ on the surface of diatomaceous earth. Figure 1 The increase of Al, C, and F elements at positions A and B in the TEM image of the cross-section of diatomite particles in D proves the successful preparation of aluminum hydroxide nanofilm on the surface of diatomite particles. At the same time, the grafting of hydrophobic long chains on the outer surface also endows the unit cell particles with excellent superhydrophobic properties.

[0051] Comparative Example 1

[0052] A method for preparing a fully hydrophobically modified superhydrophobic unit cell powder includes the following steps:

[0053] (1) Preparation of modified nanosol: By mass, 4-5 parts of ammonia (AR), 0.3-0.5 parts of surfactant (FS-30), 0.5-0.6 parts of low surface energy substance (heptadecyltriethoxysilane), and 5-8 parts of nanosol (10-20 nm silica nanosol with a solid content of 15 wt.%) were added to 80 parts of deionized water and mixed evenly under a constant temperature water bath at 50℃. After stirring and reacting for 12 h, hydrophobic modified nanosol A was obtained.

[0054] (2) Preparation of diatomaceous earth particle suspension: By mass, 4-5 parts of ammonia water (AR) and 3-5 parts of porous diatomaceous earth particles with a particle size of 10-30 micrometers were added to 80 parts of deionized water and mixed evenly under a constant temperature water bath at 50℃. After reacting for 6 hours, 0.5-1 parts of silane coupling agent KH550 were added and the mixture was stirred and reacted for another 6 hours to obtain diatomaceous earth particle suspension.

[0055] (3) Preparation of superhydrophobic unit cell powder: Nanosol A and diatomaceous earth particle suspension were mixed evenly, wherein the mass ratio of hydrophobically modified inorganic nanoparticles (10-20 nm silica nanosol, solid content of 1.6 wt.%) in nanosol A to modified diatomaceous earth particles in diatomaceous earth particle suspension was 3:10; the reaction was stirred for 12 h in a constant temperature water bath at 50℃ to obtain unit cell particle suspension; the unit cell particle suspension was dried at high temperature (drying at 150℃ for 6 h) to obtain superhydrophobic unit cell powder.

[0056] Figure 2 Fourier transform infrared curves (1205 cm⁻¹) of the superhydrophobic nanoparticles in Example 1 and Comparative Example 1 -1 The CF peak appears at 3500 cm⁻¹ -1 The disappearance of the nearby -OH peak indicates that the modified nanoparticles have achieved complete hydrophobic grafting and possess excellent superhydrophobicity. In contrast, the hydrophobic modification of diatomaceous earth alone in Example 1 under the same conditions would also deplete the already limited number of active hydroxyl sites on the diatomaceous earth surface, reducing its compatibility with the resin, leading to increased defects in the coatings prepared using it, decreased particle adhesion, and insufficient mechanical stability. The unit cell structure obtained in Example 1 simultaneously exhibited a 1205 cm⁻¹ peak after the addition of aluminum hydroxide. -1 The CF peak appears at 3500 cm⁻¹ -1 Near the -OH peak, Example 1 achieved the preparation of heterogeneous surface unit cell particles. The abundant hydroxyl sites in these particles help improve the compatibility between the unit cell particles and the resin, reducing coating defects. Furthermore, chemical bonds are formed between the unit cell particles and the resin, which... Figure 2 Example 2: Fourier transform infrared curve of composite anti-corrosion coating at 3500 cm⁻¹ -1 The disappearance of the nearby -OH peak confirms that the present invention can improve the crosslinking degree of the composite anti-corrosion coating, thereby improving the mechanical stability of the coating. Figure 3 The high F-peak surface unit cells in the XPS curves of the unit cell particles obtained in Example 1 also have a high hydrophobic long-link branching rate, which ensures their high steric hindrance capability against water of various phases in the coating. Figure 4 The hardness and Young's modulus of the diatomaceous earth particles prepared in Comparative Example 1 and the unit cell particles in Example 1 show that the strong alumina coating effectively improves the mechanical strength of the unit cell particles, which is beneficial to improving their mechanical wear resistance. Figure 5The differences in hydrophobicity between nanoparticles, diatomaceous earth particles, and unit cell particles in Example 1 and Comparative Example 1 indicate that loading superhydrophobic nanoparticles is beneficial to improving the hydrophobicity of unit cell particles, thereby enhancing their steric hindrance to water. Furthermore, unit cell particles also exhibit real-time hydrophobic self-healing properties after physical damage.

[0057] Example 2

[0058] The method for forming a composite anti-corrosion coating based on the superhydrophobic unit cell powder prepared in Example 1 is as follows: by mass, 2.5 parts of superhydrophobic unit cell powder, 5 parts of epoxy resin and 15 parts of butyl acetate are mixed and stirred for 30 min at room temperature, then 2 parts of curing agent (cycloaliphatic amine) are added, and after stirring evenly, the mixture is densely sprayed (flow rate of 5 mL / min, pressure of 0.6 bar, spraying distance of 5 cm) onto the surface of the substrate with the pre-cured epoxy coating, and cured at room temperature of 25°C for 24 h to obtain a composite anti-corrosion coating with a coating thickness of 80-100 μm.

[0059] Comparative Example 2

[0060] By mass, 2.5 parts of superhydrophobic unit cell powder, 5 parts of epoxy resin and 15 parts of butyl acetate were mixed and stirred for 30 min at room temperature. Then, 2 parts of curing agent (cycloaliphatic amine) were added and stirred evenly. The mixture was then loosely sprayed (flow rate of 2.5 mL / min, pressure of 0.4 bar, spraying distance of 10 cm) onto the surface of a substrate with a pre-cured epoxy coating. The coating was cured at room temperature (25℃) for 24 h to obtain a composite anti-corrosion coating with a thickness of 80-100 μm.

[0061] Figure 6 The surface and cross-sectional morphology of the hydrophobic and superhydrophobic composite anticorrosive coatings in Example 2 and Comparative Example 2 show that to achieve superhydrophobicity of the coating, it is necessary to sacrifice the dense structure of the coating and prepare a coating as described above. Figure 6 The rough-structured coatings shown in C and D exhibit excellent superhydrophobicity and superior surface anti-wetting properties against liquid corrosive media. Figure 7 The pore size distribution of the two composite anti-corrosion coatings in Example 2 and Comparative Example 2 shows that the superhydrophobic composite anti-corrosion coating has more coating pore defects larger than 200 nm. When resisting gaseous corrosive media, the superhydrophobicity is easily compromised. These large defects become channels for the rapid expansion of corrosive media, leading to rapid corrosion. Therefore, when facing multiphase corrosion, Figure 6 The densely sprayed hydrophobic composite anti-corrosion coatings in A and B exhibit superior overall corrosion resistance.

[0062] Comparative Example 3

[0063] By mass, 2.5 parts of original unit cell powder (original unit cell powder refers to inorganic nanoparticles in unit cell particles that have not been hydrophobically modified, i.e., have not been grafted with fluorocarbon chains), 5 parts of epoxy resin, and 15 parts of butyl acetate were mixed and stirred for 30 min at room temperature. Then, 2 parts of curing agent (cycloaliphatic amine) were added and stirred evenly. The mixture was then densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto the surface of a substrate with a pre-cured epoxy coating. The coating was cured at room temperature (25℃) for 24 h to obtain a composite anti-corrosion coating with a thickness of 80-100 μm.

[0064] Comparative Example 4

[0065] By weight, 2.5 parts alumina powder, 5 parts epoxy resin and 15 parts butyl acetate were mixed and stirred for 30 min at room temperature. Then, 2 parts curing agent (cycloaliphatic amine) were added and stirred evenly. The mixture was then densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto the surface of a substrate with a pre-cured epoxy coating. The coating was cured at room temperature (25℃) for 24 h to obtain an alumina anti-corrosion coating with a thickness of 80-100 μm.

[0066] Comparative Example 5

[0067] By weight, 2.5 parts of glass flake powder, 5 parts of epoxy resin and 15 parts of butyl acetate were mixed and stirred for 30 min at room temperature. Then, 2 parts of curing agent (cycloaliphatic amine) were added and stirred evenly. The mixture was then densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto the surface of a substrate with a pre-cured epoxy coating. The coating was cured at room temperature (25℃) for 24 h to obtain a glass flake powder anti-corrosion coating with a thickness of 80-100 μm.

[0068] Comparative Example 6

[0069] Existing three-layer graphene anti-corrosion coating:

[0070] (1) By mass, at room temperature, 5 parts of graphene primer HGCP1101 and 15 parts of commercial paint thinner are stirred for 30 minutes, and then 0.5 parts of the matching curing agent are added. After stirring evenly, the mixture is densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto a clean metal substrate. After curing at room temperature 25℃ / 24h, HGCP1101 graphene primer is obtained.

[0071] (2) By mass, at room temperature, 5 parts of graphene intermediate paint HGNI2302 and 15 parts of commercial paint thinner are stirred for 30 minutes, and then 1 part of the matching curing agent is added. After stirring evenly, the mixture is densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto the metal substrate coated with HGCP1101 graphene primer. After curing at room temperature 25℃ / 24h, a double-layer graphene anti-corrosion coating is obtained.

[0072] (3) By mass, at room temperature, 5 parts of graphene topcoat HCP2702 and 15 parts of commercial paint thinner are stirred for 30 minutes, and then 1 part of the matching curing agent is added. After stirring evenly, the mixture is densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto the metal substrate coated with double-layer graphene anti-corrosion paint. After curing at room temperature 25℃ / 24h, a three-layer commercial graphene anti-corrosion coating is obtained with a coating thickness of 200~250μm.

[0073] Example 3

[0074] By weight, 2.5 parts of superhydrophobic unit cell powder, 5 parts of epoxy resin and 15 parts of butyl acetate were mixed and stirred for 30 min at room temperature. Then, 2 parts of curing agent (cycloaliphatic amine) were added and stirred evenly. The mixture was then densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto the iron substrate of anchor chain material containing marine anti-corrosion zinc-rich epoxy coating. After curing at room temperature of 25℃ for 24 h, a composite anti-corrosion coating (Cellular-Gray) with a thickness of 250-300 μm was obtained.

[0075] Comparative Example 7

[0076] Commercial marine-grade graphene anti-corrosion topcoat was densely sprayed (flow rate 5 mL / min, pressure 0.6 bar, spraying distance 5 cm) onto the iron substrate of anchor chain material containing zinc-rich epoxy coating at room temperature. After curing at room temperature for 25℃ / 24h, a graphene composite anti-corrosion coating (GO-Blue) was obtained with a coating thickness of 250-300 μm.

[0077] Example 4

[0078] The composite anti-corrosion coating prepared in Example 2 was immersed in a 3.5 wt.% NaCl solution at room temperature to a depth of 50 mm. As the immersion test continued, the immersed sample was removed every other day. After the surface droplets were absorbed with a cotton cloth, the water droplet contact angle and sliding angle were immediately tested to evaluate the changes in the wettability of the dense anti-corrosion coating surface during the immersion process.

[0079] Example 5

[0080] The composite anti-corrosion coating prepared in Example 2 was placed in a 5 wt.% NaCl salt spray environment at 35°C for a neutral salt spray experiment, with a salt spray deposition rate of 1–2 mL / h. As the salt spray test continued, salt spray samples were taken out every other day, and after the surface droplets were absorbed with a cotton cloth, the water droplet contact angle and sliding angle were immediately tested to evaluate the change in surface wettability of the dense anti-corrosion coating during the salt spray corrosion process.

[0081] Example 6

[0082] The composite anti-corrosion coating prepared in Example 2 was subjected to wear tests on a Taber abrasion tester at room temperature. The grinding wheel model was CS-10, the load was 1 kg, and the grinding wheel speed was 60 r / min. As the number of wear cycles increased, the wear sample was taken off every 200 r. After the surface wear material was blown off with a strong N2 airflow, the water droplet contact angle and sliding angle were immediately tested to evaluate the change in surface wettability of the dense anti-corrosion coating during the wear process.

[0083] Figure 8 The composite anti-corrosion coating of Example 2, due to its superhydrophobic unit cell filler, chemical bonding between the unit cell and the resin, and dense coating structure, ensures that the coating maintains its excellent hydrophobicity during the one-week salt water immersion, one-week salt spray erosion, and 1000r physical wear processes of Examples 4-6. This indicates that the composite anti-corrosion coating of Example 2 can effectively prevent corrosive media from wetting and penetrating the coating under these three external environments, demonstrating that the coating has long-term anti-corrosion capability.

[0084] Example 7

[0085] The composite anti-corrosion coating of Example 2 was immersed in a 3.5 wt.% NaCl solution at room temperature to a depth of 50 mm. After 112 days, the immersed sample was removed and transferred to a three-electrode electrochemical test dish for low-frequency impedance and strong polarization curve testing. The counter electrode was a Pt electrode, the reference electrode was a saturated calomel electrode, and the working electrode was the sample to be tested after 112 days of immersion. The electrochemical workstation was a Princeton P4000.

[0086] At room temperature, various types of composite anti-corrosion coatings prepared in Comparative Examples 3-6 were immersed in a 3.5 wt.% NaCl solution to a depth of 50 mm. After 112 days of continuous immersion testing, the immersed samples were removed and transferred to a three-electrode electrochemical test dish for low-frequency impedance and strong polarization curve testing. The counter electrode was a Pt electrode, the reference electrode was a saturated calomel electrode, and the working electrode was the sample to be tested after 112 days of immersion. The electrochemical workstation was a Princeton P4000.

[0087] Figure 9In Example 2, after immersion in 3.5 wt.% NaCl brine for 112 days, the composite anti-corrosion coating still maintained a corrosion resistance level above 10. 9 Ω·cm -2 It exhibits low-frequency impedance and the lowest corrosion potential and corrosion current density. Whether compared to existing technologies such as the bottom-surface composite anti-corrosion coatings of Comparative Examples 4-5 or the bottom-middle-surface composite anti-corrosion coating of Comparative Example 6, the composite anti-corrosion coating of this invention consistently demonstrates excellent corrosion resistance.

[0088] Example 8

[0089] The composite anti-corrosion coating of Example 2 was placed in a 5wt.% NaCl salt spray environment at 35℃ for a neutral salt spray experiment, with a salt spray deposition rate of 1-2 mL / h. After 2500 h of salt spray testing, the salt spray sample was taken out and observed using SEM electron microscopy combined with EDS elemental surface scanning to study the surface cross-sectional morphology and Cl ion penetration of the composite anti-corrosion coating after salt spray corrosion.

[0090] Figure 10 The composite anti-corrosion coating of Example 2, after 2500 hours of salt spray corrosion, showed the following properties: Figure 10 As shown in Figure A, almost all chloride ion corrosive media are blocked on the coating surface, and the longitudinal dense structure of the coating is not damaged. Figure 10 B), and as Figure 10 As shown in the EDS elemental surface scan of C, Cl - It is difficult for it to penetrate into the interior of the coating and cannot come into contact with the metal substrate to be protected, thus achieving an ultra-long anti-corrosion life of the composite anti-corrosion coating.

[0091] like Figure 11 As the salt spray corrosion continued, the corrosion resistance advantage of the composite anti-corrosion coating in Example 2 became increasingly apparent compared to the three-layer commercial graphene composite anti-corrosion coating on the bottom and middle surfaces of Comparative Example 6. Throughout 3000 hours of salt spray corrosion, the coating in Example 2 consistently exhibited excellent salt spray corrosion resistance. After 2500 hours, both the composite anti-corrosion coatings of Example 2 and Comparative Example 6 underwent a 500-hour long-term static placement followed by a 500-hour salt spray test to simulate the coating's salt spray corrosion resistance under alternating wet and dry conditions. It was found that the coating in Example 2 only showed slight corrosion at the artificially scratched areas, while the three-layer commercial graphene composite anti-corrosion coating on the bottom and middle surfaces of Comparative Example 6 showed severe salt spray corrosion in most areas. Therefore, the coating of this invention, even with a thin coating layer, can achieve superior salt spray corrosion resistance under alternating wet and dry conditions.

[0092] The composite anti-corrosion coating of Example 3 and the commercial bottom composite anchor chain anti-corrosion coating of Comparative Example 7 were subjected to a 2500-hour salt spray test according to ASTM-B117 standard. The coating adhesion (ASTM-D4541), corrosion resistance (ISO-4628), abrasion resistance (ASTM-D4060), and impact resistance (ASTM-G14) were compared during the salt spray test.

[0093] like Figure 12 As shown, the salt spray corrosion test had little effect on the adhesion of the composite anti-corrosion coating of Example 3 and the commercial bottom composite anchor chain anti-corrosion coating of Comparative Example 7. The coating of Example 3 had the same excellent adhesion as the commercial bottom composite anchor chain anti-corrosion coating, and the adhesion met the current requirements for commercial marine anti-corrosion coatings.

[0094] The superhydrophobic unit cell design of this invention forms chemical bonds with the resin, effectively improving the adhesion of the unit cell particles. Simultaneously, the hardening of the unit cell particles enhances the strength of the resin coating. The combined effect improves the wear resistance of the coating. The mass loss of the unit cell composite anti-corrosion coating after wear is always less than that of commercial bottom-surface composite anchor chain anti-corrosion coatings. Figure 13 As shown, during the salt spray corrosion test, the composite anti-corrosion coating of Example 3 had a mass loss of 13.5 to 80.4 mg less than the commercial bottom composite anchor chain anti-corrosion coating in Comparative Example 7, demonstrating excellent wear resistance.

[0095] Furthermore, according to the ASTM-G14 standard, the overall impact resistance of the composite anti-corrosion coating in Example 3 and the commercial bottom-surface composite anchor chain anti-corrosion coating in Comparative Example 7 were 6.50 N·m and 5.84 N·m, respectively, with the composite anti-corrosion coating in Example 3 exhibiting superior impact resistance. Figure 14 As shown, after 2500 hours of salt spray corrosion testing, all composite anti-corrosion coatings in Example 3 passed the 0.4m steel ball impact test, while all commercial bottom composite anchor chain anti-corrosion coatings in Comparative Example 7 failed the test. The composite anti-corrosion coating in Example 3 has superior impact resistance.

[0096] The corrosion resistance of the composite anti-corrosion coating of Example 3 was further calibrated after a 2000-hour salt spray test, with bubbling meeting ISO-4628-2 standard 0S(0) grade and rust meeting ISO-4628-3 standard R. i = Grade 0, corrosion cracking ISO-4628-3 standard 0(S0) grade, spalling grade ISO-4628-4 standard 0S(0) grade, such as Figure 15 As shown, after a 2500-hour salt spray corrosion test, the composite anti-corrosion coating of Example 3 showed no corrosion, while the commercial bottom composite anchor chain anti-corrosion coating of Comparative Example 7 showed significant corrosion. This indicates that the composite anti-corrosion coating of the present invention has superior corrosion resistance.

[0097] The superhydrophobic unit cell powder prepared by the method of this invention can be applied to various resin systems with specific functional groups to form coatings, which significantly improves the hydrophobic stability, structural density and mechanical wear resistance of the final composite coating. Furthermore, the interlaced unit cell particles and dense longitudinal coating structure in the resin can effectively increase the diffusion resistance of corrosive media, extend the penetration path and corrosion inhibition performance, thereby ensuring that the coating has excellent corrosion resistance when facing corrosive media in various phases of water.

Claims

1. Use of a superhydrophobic unit cell powder in the preparation of a composite anticorrosive coating, characterized in that, Specifically, 2.5-3 parts of the super-hydrophobic unit cell powder, 5-6 parts of the resin and 15-18 parts of the organic solvent are mixed and stirred at room temperature, 1.5-2 parts of the curing agent is then added, and after uniform stirring, the mixture is densely sprayed onto the surface of the substrate with a pre-cured epoxy coating, and a composite anti-corrosion coating is obtained after room temperature curing; During the spraying process, the flow rate is 5 mL / min, the pressure is 0.6 bar, and the spraying distance is 5 cm; The super-hydrophobic unit cell powder is composed of particles in a unit cell structure; each unit cell particle has a super-hydrophobic round diatomite shell, and the round diatomite has a hollow porous structure; the hollow cavity of the diatomite is filled with super-hydrophobic inorganic nanoparticles and corrosion inhibitor filled in the gaps between the inorganic nanoparticles, and a membrane for sealing the pores is arranged at the pore structure of the diatomite shell, and the membrane is a composite membrane layer constructed by a cationic polymer and an anionic polymer; The preparation method of the super-hydrophobic unit cell powder comprises the following steps: (1) Preparation of modified nano sol: 4-5 parts of ammonia, 0.3-0.5 parts of surfactant, 0.5-0.6 parts of low surface energy substance and 5-8 parts of nano sol are added to 80-90 parts of deionized water under constant temperature water bath, mixed uniformly, and after stirring reaction, a hydrophobic modified nano sol A is obtained; (2) Preparation of coated diatomite particle suspension: 4-5 parts of ammonia, 0.7-1.2 parts of aluminum hydroxide and 3-5 parts of porous diatomite particles are added to 80-90 parts of deionized water under constant temperature water bath, mixed uniformly, and after reaction for 5-6 hours, 0.5-1 parts of silane coupling agent is added, and the stirring reaction is continued for 5-6 hours to obtain a coated diatomite particle suspension; (3) Preparation of super-hydrophobic unit cell particles: the hydrophobic modified nano sol A and the coated diatomite particle suspension are mixed, and after stirring under constant temperature water bath, a unit cell particle suspension is obtained; the corrosion inhibitor is added to the unit cell particle suspension until a saturated corrosion inhibitor solution is formed, vacuum is used to remove air in the pores of the unit cell particles, the saturated corrosion inhibitor solution enters the cavities of the unit cell particles, and the corrosion inhibitor is loaded; after loading the corrosion inhibitor, the unit cell particle suspension is dried at high temperature to obtain super-hydrophobic unit cell particles; In the mixing process of the hydrophobic modified nano sol A and the coated diatomite particle suspension, the mixing mass ratio of the super-hydrophobic modified inorganic nanoparticles in the hydrophobic modified nano sol A to the modified diatomite particles in the coated diatomite particle suspension is 3-3.5:10; (4) The unit cell particles are subjected to pore sealing treatment to obtain sealed super-hydrophobic unit cell powder.

2. Use according to claim 1, characterized in that: The particle size of the unit cell particles is 10-30 microns; the pore size of the pores on the diatomite shell is 120-300 nm, and the particle size of the inorganic nanoparticles is smaller than the pore size of the pores on the diatomite shell.

3. Use according to claim 1, characterized in that: The inorganic nanoparticles are silicon dioxide nanoparticles, aluminum oxide nanoparticles or titanium dioxide nanoparticles, and the particle size of the inorganic nanoparticles is 10-20 nm.

4. Use according to claim 1, characterized in that: In step (1), the surfactant is at least one of NEO-4990, FS-3100, FS-61 or FS-30; the low surface energy substance is at least one of tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane or heptadecafluorodecyltriethoxysilane; and the nanosol is a mixture of one or more of silica nanosol, alumina nanosol or titania nanosol with a nanoparticle size of 10-20 nm, and the nanosol has a solid content of 15-25 wt.%.

5. The use according to claim 1, characterized in that: In step (2), the silane coupling agent is at least one of KH550, KH560, KH570, KH580 or KH590.

6. Use according to claim 1, characterized in that: In step (3), the drying temperature is 120-180°C, and the drying time is 4-6 h.

7. The use according to claim 1, characterized in that: In step (4), the specific operation process for sealing the pores is as follows: the cationic polymer solution and the unit cell particle suspension are mixed at a volume ratio of 6:4-5, and the unit cell particle surface is covered by electrostatic action under the condition of mechanical stirring at 300-350 r / 30 min, and then the excess cationic polymer is removed by washing with ethanol or water after centrifugation at 8000-8500 r / 3 min; After the cationic polymer is covered, the unit cell particle is positively charged; then the anionic polymer solution and the unit cell particle suspension are mixed at a volume ratio of 6:4-5, and the unit cell particle surface is covered by electrostatic action under the condition of mechanical stirring at 300-350 r / 30 min, and then the excess anionic polymer is removed by washing with ethanol or water after centrifugation at 8000-8500 r / 3 min; a composite film layer constructed by the cationic polymer-anionic polymer is obtained on the surface of the pore structure of the unit cell particle, and the sealing treatment of the super-hydrophobic unit cell particle is completed.

8. The use according to claim 1, characterized in that: The resin is polyurethane, epoxy resin, fluorocarbon resin or polyurea resin.

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