Preparation method of organic-inorganic hybrid nano ceramic marine heavy anti-corrosion coating

Abstract

The invention discloses a preparation method of an organic-inorganic hybrid nano ceramic marine heavy anti-corrosion coating, and belongs to the technical field of metal material protection. The method solves the technical problems of insufficient compactness and reduced protection performance of the existing marine heavy anti-corrosion coating caused by poor compatibility of an organic phase and an inorganic phase, non-uniform dispersion of nanoparticles and inaccurate control of a curing process. According to the technical scheme, the method is characterized by comprising the following steps: respectively preparing organic sol and inorganic sol by adopting propylene glycol methyl ether acetate as a uniform solvent, mixing the organic sol and the inorganic sol according to a mass ratio of (1-2): 1 to form hybrid sol, adding nano-zirconia into the hybrid sol, performing ultrasonic dispersion to obtain mixed sol, and finally coating the surface of a pretreated base material with the mixed sol through high-pressure airless spraying, so as to obtain the nano-zirconia-coated substrate. And coating curing is completed under the temperature programming condition. The coating prepared by the method is mainly used for long-term corrosion protection of carbon steel structures of ships, ocean platforms, port facilities and the like in an ocean environment.

Description

Technical Field

[0001] This invention relates to the field of metal material protection technology. More specifically, this invention relates to a method for preparing an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating. Background Technology

[0002] In the field of marine heavy-duty anti-corrosion coating technology, organic-inorganic hybrid materials combine the flexibility of organic materials with the corrosion resistance of inorganic materials, showing promising application prospects. However, several technical challenges still need to be addressed in the existing technologies.

[0003] First, the compatibility between the organic and inorganic phases restricts the full realization of the hybrid material's performance. Since organic resins are typically hydrophobic and have low surface energy, while inorganic sol particles are rich in hydrophilic hydroxyl groups, phase separation easily occurs during mixing due to interfacial tension mismatch. This phase separation leads to microscopic or macroscopic interfacial defects within the hybrid coating, forming channels for corrosive media penetration. Especially in marine environments, corrosive media such as chloride ions can rapidly penetrate to the substrate surface through these defects, accelerating metal corrosion. Although researchers have attempted to improve the compatibility of the two phases using silane coupling agents, in practical processes, the degree of hydrolysis and condensation reactions of the coupling agents is difficult to control precisely, and the significant difference in reaction rates between the organic and inorganic phases results in incomplete chemical bonding at the interface, affecting the density and long-term stability of the hybrid coating.

[0004] Secondly, the dispersion stability of nano-ceramic particles in coatings is a significant technical challenge. Nano-zirconia and other ceramic particles possess high surface energy and specific surface area, making them prone to agglomeration during storage and processing, forming micron-sized aggregates. These aggregates not only fail to provide the reinforcing and toughening effects unique to nanoparticles but also become stress concentration points in the coating, reducing its mechanical properties and adhesion. Existing technologies typically employ physical ultrasonic dispersion or the addition of dispersants, but these methods only provide temporary dispersion effects. During coating curing, nanoparticles will re-agglomerate due to Brownian motion and van der Waals forces. Furthermore, insufficient interfacial bonding strength between nanoparticles and the matrix resin is also a prominent issue. Due to the smooth surface and strong chemical inertness of nanoparticles, interfacial bonding with organic resins relies primarily on physical adsorption, making them susceptible to interfacial delamination during long-term service, leading to a decline in coating protective performance.

[0005] Third, controlling internal stress and preventing defects in coatings during the curing process presents challenges. Organic-inorganic hybrid coatings typically employ thermosetting processes, during which solvent evaporation, organic phase crosslinking and curing, and inorganic phase condensation reactions occur simultaneously. These processes exhibit significant differences in kinetic behavior: excessively rapid solvent evaporation can lead to pinholes and bubbles on the coating surface; the crosslinking and curing of organic resins is accompanied by significant volume shrinkage, while the condensation shrinkage rate of the inorganic network is smaller. This shrinkage mismatch generates substantial internal stress within the coating. When this internal stress exceeds the adhesion between the coating and the substrate or the coating's own strength, it can cause cracking, peeling, or warping. This stress accumulation effect is particularly pronounced in thicker coatings. Existing technologies typically employ a single heating rate for curing, which struggles to simultaneously meet the multiple requirements of slow solvent evaporation, sufficient organic phase crosslinking, and complete inorganic phase condensation, resulting in residual stress and microscopic defects within the coating.

[0006] These interconnected technical challenges collectively affect the effectiveness of organic-inorganic hybrid nanoceramic coatings in marine heavy-duty corrosion protection. Poor compatibility between the organic and inorganic phases limits the density of the hybrid coating; uneven nanoparticle dispersion and weak interfacial bonding affect the coating's mechanical properties; and internal stress and defects during curing directly impact the coating's integrity and service life. Solving these problems requires systematic optimization across multiple levels, including material design, interface engineering, and process control. However, in actual technology development, these factors often interact and are difficult to balance simultaneously, becoming a major bottleneck in the development of this technology. Summary of the Invention

[0007] One object of the present invention is to provide a method for preparing an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating, the prepared coating exhibiting excellent protective performance, good mechanical properties and long-term durability in harsh marine corrosive environments.

[0008] To achieve these objectives and other advantages of the present invention, according to one aspect of the present invention, a method for preparing an organic-inorganic hybrid nanoceramic marine heavy-duty anti-corrosion coating is provided, comprising the following steps: Step 1: Dissolve the silane coupling agent and epoxy resin in propylene glycol methyl ether acetate solvent. The mass ratio of silane coupling agent to epoxy resin is 1:(1~3). The amount of propylene glycol methyl ether acetate solvent is 2~4 times the total mass of silane coupling agent and epoxy resin. Stir and react at 60~80℃ for 2~4 h to form an organic sol. Step 2: Mix tetraethyl orthosilicate and propylene glycol methyl ether acetate at a volume ratio of 1:(2~4), add deionized water, the molar ratio of deionized water to tetraethyl orthosilicate is (2~4):1, and add hydrochloric acid as a catalyst, the concentration of hydrochloric acid is 0.1~0.5 mol / L, and let it stand at 25~40℃ for 1~3 h to hydrolyze and form an inorganic sol; Step 3: Mix the organic sol obtained in Step 1 with the inorganic sol obtained in Step 2 at a mass ratio of (1~2):1, and stir at 50~70℃ for 1~2 h to form an organic-inorganic hybrid sol. Step 4: Add nano-zirconia with an average particle size of 20-50 nm to the organic-inorganic hybrid sol obtained in Step 3. The amount added is 5-15% of the total mass of the organic-inorganic hybrid sol. Disperse the mixture using an ultrasonic disperser at a power of 200-400 W for 30-60 min to obtain a mixed sol. Step 5: Apply the mixed sol obtained in Step 4 to the surface of the pretreated carbon steel substrate using a high-pressure airless spraying device. The coating thickness is 20~50 μm. After coating, let it stand at room temperature for 10~30 min to allow the solvent to evaporate. Then place it in an oven and cure it at 80~250℃ for 2~5 h to form an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating.

[0009] Preferably, the mixing process in step three specifically includes: Aluminum acetylacetone is added to all the inorganic sols prepared in step two, and the amount of aluminum acetylacetone added is 0.5-2% of the total mass of the inorganic sols. The sols are pre-aged at 40-50°C and 300-500 r / min for 1-2 h to obtain a pre-catalyzed inorganic sol. 10-20% of the total amount of the organic sol prepared in step one is slowly added to the precatalytic inorganic sol under stirring conditions for 5-10 minutes, and the system temperature is maintained at 30-40℃ during this stage. After completing the above steps, age the mixture at 40-50℃ and 300-500 r / min for 2-4 h to obtain the pre-hybridized inorganic sol. The pre-hybridized inorganic sol and the remaining organic sol from step one are stirred at 50-70°C and 150-300 r / min for 1-2 h to complete the mixing in step three, forming an organic-inorganic hybrid sol.

[0010] Preferably, the nano-zirconia particles in step four are modified nano-zirconia with epoxy functional groups grafted onto their surface, and the preparation process is as follows: Zirconia nanoparticles were dispersed in propylene glycol methyl ether acetate to form a nanoparticle suspension with a concentration of 50-100 g / L, and then pre-ultrasonically dispersed at a power of 300-500 W for 15-30 min. The nanoparticle suspension was transferred to a reactor equipped with a mechanical stirrer and a reflux condenser. Under stirring conditions, 3-8% of the mass of the nano-zirconia particles was added dropwise with the silane coupling agent KH-560, and the dropping rate was controlled to be 1-2 mL / min. After the addition is complete, the reaction system is heated to 70-80℃ and refluxed for 4-6 hours to allow the silane coupling agent to be fully hydrolyzed and undergo a condensation reaction with the hydroxyl groups on the surface of the nano-zirconia particles, thus obtaining a modified nano-zirconia suspension with epoxy functional groups grafted on its surface.

[0011] Preferably, after the preparation of the modified nano-zirconia suspension with epoxy functional groups grafted onto its surface is completed, the process further includes a post-treatment and controlled addition step, specifically: The modified nano-zirconia suspension with epoxy functional groups grafted on its surface was centrifuged and the supernatant was removed to obtain a modified nano-zirconia wet filter cake. Propylene glycol methyl ether acetate solvent is added to the wet filter cake to redisperse the modified nano-zirconia particles, forming a propylene glycol methyl ether acetate-based nanoparticle slurry with a solid content of 10-20%. The propylene glycol methyl ether acetate-based nanoparticle slurry was added to the organic-inorganic hybrid sol obtained in step three at a rate of 0.5-2 mL / min using a syringe pump under stirring conditions. Then, the sol was dispersed using an ultrasonic disperser at a power of 200-400 W for 30-60 min to uniformly disperse the nano-zirconia particles and obtain a mixed sol.

[0012] Preferably, the curing process in step five specifically includes: After coating and allowing the substrate to stand, heat it to 80-100°C at a heating rate of 1-2°C / min, and hold it at this temperature for 20-40 minutes. Continue heating at a rate of 0.5~1℃ / min to 130~150℃, and hold at this temperature for 30~60 min; Heat to 150-250℃ at a heating rate of 2-3℃ / min, and hold at this temperature for 1-3 hours to complete curing.

[0013] Preferably, before performing the coating treatment in step five, a latent curing agent is added to the mixed sol. The latent curing agent is a boron trifluoride-monoethylamine complex microcapsule coated with a polyurea shell. The shell melting temperature of the microcapsule is 140~160°C. The amount of the latent curing agent added is 2~5% of the total mass of epoxy resin in the mixed sol.

[0014] Preferably, the boron trifluoride-monoethylamine complex microcapsules coated with a polyurea shell are prepared by the following method: Boron trifluoride-monoethylamine complex powder was dispersed in hexamethylene diisocyanate to form an oil phase; The emulsifier is dissolved in deionized water to form an aqueous phase; The oil phase is added to the aqueous phase under stirring conditions, with a mass ratio of oil phase to aqueous phase of 1:(3~5). The mixture is then subjected to high-speed shear emulsification at a speed of 10000~15000 rpm for 3~5 min to form an emulsion. An aqueous solution of ethylenediamine is slowly added dropwise to the emulsion, wherein the molar ratio of ethylenediamine to hexamethylene diisocyanate is 1:(1~1.2), and the reaction is carried out at 25~35°C for 4~6 h, thereby forming a polyurea shell on the surface of boron trifluoride-monoethylamine complex particles through interfacial polymerization. After the reaction was completed, the mixture was filtered, washed with deionized water, and dried under vacuum at 40-50°C to obtain the boron trifluoride-monoethylamine complex microcapsules coated with a polyurea shell.

[0015] Preferably, the pretreatment process of the carbon steel substrate in step five includes the following steps: The surface of the carbon steel substrate is sandblasted using diamond abrasive with a particle size of 0.5~1.5 mm and a sandblasting air pressure of 0.5~0.8 MPa. After sandblasting, compressed air is used to blow away the substrate surface to remove residual abrasive dust. Subsequently, a two-stage solvent cleaning process was adopted, first wiping the substrate surface with petroleum ether, and then wiping the substrate surface with acetone. Finally, place the cleaned substrate in an oven at 80~100℃ and dry for 15~30 minutes. After removing it and cooling it to room temperature, apply the coating immediately.

[0016] The present invention offers at least the following advantages: The method for preparing the organic-inorganic hybrid nanoceramic marine heavy-duty anti-corrosion coating of the present invention effectively avoids phase separation problems that may occur when mixing multiple solvents by using a unified propylene glycol methyl ether acetate solvent system, thus improving the compatibility between components and the uniformity of the coating. Pre-inorganization treatment with aluminum acetylacetonate preferentially promotes the construction of the inorganic network, reducing side reactions with epoxy groups in the organic phase, thereby enhancing the structural integrity and stability of the hybrid network. Surface grafting modification of nano-zirconia particles and redispersing them in the same solvent system significantly improves the dispersion stability of the nanoparticles in the coating, enhances the interfacial bonding force between the particles and the matrix, and effectively leverages the reinforcing and toughening effects of the nanoparticles. The multi-stage programmed curing process, through precise control of the heating rate and holding stage, achieves stable solvent evaporation, sufficient cross-linking of the organic phase, and complete condensation of the inorganic phase, significantly reducing the formation of internal stress and micro-defects in the coating. By introducing a microencapsulated latent curing agent with a specific melting temperature, the curing reaction is ensured to be triggered at the appropriate temperature stage, avoiding the adverse effects of premature crosslinking on solvent evaporation and bubble removal, and improving the control precision of the curing process. Combined with a scientific substrate pretreatment process, a clean and moderately rough bonding surface is provided for the coating, further ensuring strong adhesion between the coating and the substrate. The synergistic effect of these technical features ultimately enables the prepared coating to exhibit excellent protective performance, good mechanical properties, and long-term durability in the harsh corrosive environment of the ocean.

[0017] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can implement it based on the description.

[0019] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0020] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0021] In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the shown orientation or positional relationship, and are only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] This invention provides a method for preparing an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating, comprising the following steps: Step 1: Dissolve the silane coupling agent and epoxy resin in propylene glycol methyl ether acetate solvent. The mass ratio of silane coupling agent to epoxy resin is 1:(1~3). The amount of propylene glycol methyl ether acetate solvent is 2~4 times the total mass of silane coupling agent and epoxy resin. Stir and react at 60~80℃ for 2~4 h to form an organic sol. Step 2: Mix tetraethyl orthosilicate and propylene glycol methyl ether acetate at a volume ratio of 1:(2~4), add deionized water, the molar ratio of deionized water to tetraethyl orthosilicate is (2~4):1, and add hydrochloric acid as a catalyst, the concentration of hydrochloric acid is 0.1~0.5 mol / L, and let it stand at 25~40℃ for 1~3 h to hydrolyze and form an inorganic sol; Step 3: Mix the organic sol obtained in Step 1 with the inorganic sol obtained in Step 2 at a mass ratio of (1~2):1, and stir at 50~70℃ for 1~2 h to form an organic-inorganic hybrid sol. Step 4: Add nano-zirconia with an average particle size of 20-50 nm to the organic-inorganic hybrid sol obtained in Step 3. The amount added is 5-15% of the total mass of the organic-inorganic hybrid sol. Disperse the mixture using an ultrasonic disperser at a power of 200-400 W for 30-60 min to obtain a mixed sol. Step 5: Apply the mixed sol obtained in Step 4 to the surface of the pretreated carbon steel substrate using a high-pressure airless spraying device. The coating thickness is 20~50 μm. After coating, let it stand at room temperature for 10~30 min to allow the solvent to evaporate. Then place it in an oven and cure it at 80~250℃ for 2~5 h to form an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating.

[0023] In the above technical solution, during the preparation of the organosol, the equipment can be a reactor with heating and stirring functions, such as a conventional glass reactor, equipped with an electric stirrer and a temperature controller. Regarding materials, the silane coupling agent can be KH-550 or KH-560, the epoxy resin can be bisphenol A type epoxy resin, and propylene glycol methyl ether acetate is an industrial-grade solvent. The reactor can be installed in a fume hood, with the stirrer located at the top and the temperature sensor inserted into the reaction solution. During operation, the silane coupling agent and epoxy resin are first added to the solvent, stirring and heating are started, and the rotation speed is controlled at 200-400 rpm to ensure the materials are fully dissolved and reacted, forming a uniform organosol. The parameter setting method is based on pre-experimentation, and the raw materials are commercially available chemical products. Functional testing can be conducted by measuring the viscosity and stability of the sol, with small batches of samples as the experimental subjects. The experimental methods include observing whether the sol separates into layers or precipitates.

[0024] In the preparation of the inorganic sol, the equipment can be a glass beaker or a plastic container, equipped with a magnetic stirrer or a manual stirring tool. For materials, tetraethyl orthosilicate is industrial grade, hydrochloric acid is analytical grade, and propylene glycol methyl ether acetate is the same. The container can be placed on a room-temperature stable laboratory bench, with the stirrer in the center. During the process, tetraethyl orthosilicate is first mixed with the solvent, then deionized water and hydrochloric acid are added. After gentle stirring, the mixture is allowed to stand to allow the hydrolysis reaction to proceed smoothly, forming a transparent inorganic sol. Parameter settings are based on hydrolysis reaction kinetics, and the raw materials are sourced from common chemical suppliers. Functional testing involves detecting the pH value and gel time of the sol, using laboratory-prepared samples as the experimental subjects, and experimental methods include observing the transparency and flowability of the sol.

[0025] In the hybrid sol mixing and nanoparticle dispersion process, the equipment can be a heated mixing container and an ultrasonic disperser, such as a laboratory ultrasonic processor. For materials, nano-zirconia is a commercially available product with an average particle size in the range of 20-50 nanometers. The mixing container can be positioned near the ultrasonic instrument, with the stirrer and ultrasonic probe working in coordination. During the process, the organic and inorganic sols are first mixed and stirred, then nano-zirconia is added, and ultrasonic dispersion is initiated to uniformly disperse the particles and form a stable mixed sol. The parameter setting method is optimized through particle size analysis, and the raw materials are sourced from nanomaterial suppliers.

[0026] During the coating and curing process, high-pressure airless spraying equipment and programmed temperature-controlled ovens can be selected, such as industrial sprayers and electric heating ovens; for materials, the carbon steel substrate is ordinary Q235 steel. The spraying equipment can be installed in the spraying workshop, with the spray gun maintained at a distance of 20-30 cm from the substrate, and the oven located near the spraying area. During operation, the mixed sol is first sprayed onto the pre-treated substrate, allowed to stand to evaporate the solvent, and then transferred to the oven. The temperature is increased and maintained according to the set program to complete the coating curing. Parameter settings are based on the coating thickness and curing curve, and the raw materials are sourced from the metal materials market.

[0027] This method, by optimizing the solvent system and controlling the reaction conditions and process parameters, can prepare organic-inorganic hybrid nanoceramic coatings with good density and uniformity. These coatings exhibit high adhesion and corrosion resistance in marine environments, while the process is stable, easy to implement and repeat.

[0028] In other technical solutions, the mixing process in step three specifically involves: Aluminum acetylacetone is added to all the inorganic sols prepared in step two, and the amount of aluminum acetylacetone added is 0.5-2% of the total mass of the inorganic sols. The sols are pre-aged at 40-50°C and 300-500 r / min for 1-2 h to obtain a pre-catalyzed inorganic sol. 10-20% of the total amount of the organic sol prepared in step one is slowly added to the precatalytic inorganic sol under stirring conditions for 5-10 minutes, and the system temperature is maintained at 30-40℃ during this stage. After completing the above steps, age the mixture at 40-50℃ and 300-500 r / min for 2-4 h to obtain the pre-hybridized inorganic sol. The pre-hybridized inorganic sol and the remaining organic sol from step one are stirred at 50-70°C and 150-300 r / min for 1-2 h to complete the mixing in step three, forming an organic-inorganic hybrid sol.

[0029] In the above technical solution, a reaction vessel equipped with a mechanical stirring and temperature control system can be used as the main equipment in the pre-catalytic inorganic sol preparation process. Aluminum acetylacetonate is an industrial-grade chemical reagent, and the inorganic sol comes from the preparation product of step two. The reaction vessel should be placed on a stable experimental platform, the temperature sensor should be inserted below the liquid surface, and the stirrer should be placed in the center of the vessel. During the operation, the inorganic sol is first added to the vessel, the temperature control system is turned on to maintain 40 to 50 degrees Celsius, then aluminum acetylacetonate is added, and stirring is continued at a speed of 300 to 500 rpm for 1 to 2 hours. The parameter settings are adjusted according to the changes in sol viscosity, and the raw materials are sourced from chemical product suppliers. This step lays the foundation for the subsequent hybridization process by preferentially catalyzing the condensation of the inorganic phase.

[0030] In the initial mixing stage of the organosol, a metering pump and a variable-speed stirrer can be used as the main equipment. The organosol is taken from the preparation product of step one, and the precatalytic inorganic sol comes from the previous process. The metering pump should be installed above the reaction vessel and connected to the vessel through a pipeline, while the stirrer is located inside the vessel. During operation, a portion of the organosol is placed in the metering pump, and the flow rate is controlled to uniformly add the precatalytic inorganic sol over 5 to 10 minutes, while maintaining the system temperature at 30 to 40 degrees Celsius and the stirring speed at 200 to 400 rpm. This step promotes the initial fusion of the two phases at the interface by controlling the addition rate of the organic phase.

[0031] In the aging process of the pre-hybridized sol, a constant-temperature shaker or a static aging device can be used. The mixing system comes from the previous step and no additional materials are required. The equipment should be placed in a light-proof, vibration-free environment, and the container should be sealed. During the operation, the mixing system is left to stand at 40 to 50 degrees Celsius for 2 to 4 hours, during which time the container is kept still or subjected to low-speed shaking. This step provides a stable reaction environment, allowing for further interaction between the two phases. The source of raw materials is the same as in the previous steps, and the parameter settings are determined based on the sol-gel transition point.

[0032] In the final hybrid sol formation stage, a mixing and stirring device with heating function can be used. The pre-hybridized inorganic sol comes from the aging process, and the remaining organic sol comes from step one. The stirring device should be located in a well-ventilated area, with the stirring paddle maintained at an appropriate distance from the bottom of the container. During operation, the two sols are added to the container in proportion and stirred at 150 to 300 rpm for 1 to 2 hours at 50 to 70 degrees Celsius. The parameter settings are adjusted according to the rheological properties of the final sol, and the raw material source is the same as in the aforementioned steps. This step completes the thorough mixing of the two phases, forming a stable hybrid sol system.

[0033] The synergistic effect of these technical features improves the compatibility between the organic and inorganic phases, promotes chemical bonding between the two phases, and reduces phase separation, thereby enhancing the uniformity and stability of the hybrid coating. Stepwise mixing and aging processes help form a denser hybrid network structure, providing a good foundation for subsequent coating preparation.

[0034] In other technical solutions, the nano-zirconia particles in step four are modified nano-zirconia with epoxy functional groups grafted onto their surface, and the preparation process is as follows: Zirconia nanoparticles were dispersed in propylene glycol methyl ether acetate to form a nanoparticle suspension with a concentration of 50-100 g / L, and then pre-ultrasonically dispersed at a power of 300-500 W for 15-30 min. The nanoparticle suspension was transferred to a reactor equipped with a mechanical stirrer and a reflux condenser. Under stirring conditions, 3-8% of the mass of the nano-zirconia particles was added dropwise with the silane coupling agent KH-560, and the dropping rate was controlled to be 1-2 mL / min. After the addition is complete, the reaction system is heated to 70-80℃ and refluxed for 4-6 hours to allow the silane coupling agent to be fully hydrolyzed and undergo a condensation reaction with the hydroxyl groups on the surface of the nano-zirconia particles, thus obtaining a modified nano-zirconia suspension with epoxy functional groups grafted on its surface.

[0035] In the above technical solution, an ultrasonic disperser and a glass container can be used as the main equipment in the surface modification process of nano-zirconia. The nano-zirconia particles can be of an average particle size of 20 nanometers, and propylene glycol methyl ether acetate can be an industrial-grade solvent. The probe of the ultrasonic disperser should be immersed 2 to 3 centimeters below the surface of the suspension, and the glass container should be placed on a vibration-resistant platform. During the operation, the nano-zirconia and solvent are first mixed in a specific ratio, then ultrasonic treatment is initiated with a power setting of 300 watts and a dispersion time of 15 minutes. The parameter settings are determined based on the concentration of the suspension, and the raw materials are sourced from a professional nanomaterial supplier.

[0036] During the addition of the silane coupling agent, a constant-pressure dropping funnel and a mechanical stirrer can be used as the main equipment. The silane coupling agent can be KH-560, and the nanoparticle suspension comes from the previous process. The dropping funnel should be installed at the top of the reactor, and the stirrer should be placed in the center. During operation, the reaction system is heated to 70 degrees Celsius, and the silane coupling agent is added dropwise at a rate of 1 ml per minute while stirring. The stirring speed is maintained at a stable 200 rpm during the addition to ensure uniform dispersion of the coupling agent. The parameter settings are based on the hydrolysis characteristics of the coupling agent, and the raw materials are sourced from chemical product manufacturers.

[0037] In the reflux reaction stage, a condenser and a temperature controller can be used as the main equipment. The reaction system contains a suspension in which the coupling agent has been added dropwise. The condenser should be installed vertically above the reactor, with the cooling water inlet and outlet connected to a water source. During operation, the reaction temperature is maintained at 80 degrees Celsius, and continuous stirring is carried out for 4 hours in a reflux reaction. During the reaction, the temperature is kept constant by the temperature controller, and the stirring speed is maintained at 150 rpm. The parameter settings are determined based on the surface grafting reaction kinetics, and the raw material source is the same as in the aforementioned steps.

[0038] The implementation of these technical features enables the grafting of epoxy functional groups onto the surface of nanoparticles, improving the dispersion stability of nanoparticles in the organic phase and enhancing the interfacial bonding force between nanoparticles and the matrix material. Through surface modification, nanoparticles can be more uniformly dispersed in the coating system, reducing agglomeration and thus improving the density and mechanical properties of the coating.

[0039] In other technical solutions, after the preparation of the modified nano-zirconia suspension with epoxy functional groups grafted on its surface is completed, a post-treatment and controlled addition step is also included, specifically: The modified nano-zirconia suspension with epoxy functional groups grafted on its surface was centrifuged and the supernatant was removed to obtain a modified nano-zirconia wet filter cake. Propylene glycol methyl ether acetate solvent is added to the wet filter cake to redisperse the modified nano-zirconia particles, forming a propylene glycol methyl ether acetate-based nanoparticle slurry with a solid content of 10-20%. The propylene glycol methyl ether acetate-based nanoparticle slurry was added to the organic-inorganic hybrid sol obtained in step three at a rate of 0.5-2 mL / min using a syringe pump under stirring conditions. Then, the sol was dispersed using an ultrasonic disperser at a power of 200-400 W for 30-60 min to uniformly disperse the nano-zirconia particles and obtain a mixed sol.

[0040] In the above technical solution, a benchtop centrifuge can be used as the main equipment in the centrifugation separation step, and the centrifuge tubes can be made of polypropylene. The modified nano-zirconia suspension with epoxy functional groups grafted onto its surface comes from the previous preparation process, and propylene glycol methyl ether acetate can be an industrial-grade solvent. The centrifuge should be placed on a level and stable experimental platform, and the centrifuge tubes should be symmetrically placed in the rotor slots. During operation, the suspension is evenly dispensed into the centrifuge tubes, the centrifugation speed is set to 3000 rpm, and the centrifugation time is 10 minutes. After completion, the supernatant is removed, and the bottom wet filter cake is collected. The parameter settings are based on the sedimentation characteristics of nanoparticles and are determined through pre-experiment optimization. The raw materials are sourced from chemical product suppliers.

[0041] In the redispersing step, an ultrasonic disperser and a glass beaker can be used as the main equipment. The wet filter cake comes from the centrifugal separation process, and the propylene glycol methyl ether acetate solvent is the same as described above. The probe of the ultrasonic disperser should be vertically inserted 2 cm below the liquid surface, and the beaker is placed on a shock-absorbing pad. During the operation, an appropriate amount of solvent is added to the wet filter cake to adjust the solid content to 15%, and ultrasonic treatment is started. The power is set to 300 watts, and the dispersion time is controlled at 45 minutes until a homogeneous slurry is formed. The parameter settings are adjusted according to the rheological properties of the slurry, and the raw material source is the same as in the previous steps.

[0042] In the controlled addition and dispersion steps, a syringe pump, mechanical stirrer, and ultrasonic disperser can be selected as the main equipment. The nanoparticle slurry comes from the redispersion process, and the organic-inorganic hybrid sol comes from step three of claim 1. The syringe pump should be fixed on a support, with the outlet pipe extending above the liquid surface in the mixing container, and the stirring paddle placed at the bottom of the container. During operation, the syringe pump is started and the slurry is slowly added at a rate of 1 ml per minute, while the stirrer is turned on to maintain a speed of 200 rpm. After the addition is complete, the mixture is treated with an ultrasonic disperser at 300 watts for 45 minutes. The parameter settings are determined based on the compatibility of the mixed system, and the raw materials are the products of the aforementioned processes.

[0043] The implementation of these technical features can improve the dispersion stability of nanoparticles in hybrid sols and reduce particle aggregation through solvent replacement and controlled addition processes. By precisely controlling the addition rate and dispersion conditions, the uniform mixing of nanoparticles with the matrix material is promoted, which helps to form a denser coating structure and improve the overall performance of the coating.

[0044] In other technical solutions, the curing process in step five is specifically as follows: After coating and allowing the substrate to stand, heat it to 80-100°C at a heating rate of 1-2°C / min, and hold it at this temperature for 20-40 minutes. Continue heating at a rate of 0.5~1℃ / min to 130~150℃, and hold at this temperature for 30~60 min; Heat to 150-250℃ at a heating rate of 2-3℃ / min, and hold at this temperature for 1-3 hours to complete curing.

[0045] In the above technical solution, a programmable temperature-controlled oven can be used as the main equipment in the first stage of the curing process. The substrate, after coating and settling, comes from the previous process and requires no additional material. The oven should be placed on a level surface, and the temperature sensor should be installed in a suitable position inside the oven cavity. During operation, the substrate is placed smoothly into the oven, the heating program is set, and the temperature is raised from room temperature to 90 degrees Celsius at a rate of 1.5 degrees Celsius per minute, and then maintained at that temperature for 30 minutes. The parameter settings are determined based on the solvent evaporation characteristics, and the raw material is obtained from the previous process.

[0046] In the second stage of the curing process, the same programmable temperature oven can be used. The substrate treated in the first stage is used as the raw material for this stage. The oven's temperature control system should operate continuously, with heating elements evenly distributed on the inner wall of the oven. During operation, after completing the first stage of heat preservation, the heating rate is adjusted to 0.8 degrees Celsius per minute, and heating continues until 140 degrees Celsius is reached, then maintained for 45 minutes. The parameter settings are determined based on the initial crosslinking characteristics of the resin, and the raw material source is the substrate treated in the previous stage.

[0047] In the third stage of the curing process, a programmed temperature-controlled oven can be used to complete the final treatment. The substrate treated in the first two stages is used as the raw material for this stage. The oven's ventilation system should be kept in normal working order to ensure uniform temperature distribution. During the process, after completing the second stage of heat preservation, the heating rate is adjusted to 2.5 degrees Celsius per minute, and heating continues to 200 degrees Celsius, where it is maintained for 120 minutes. The parameter settings are determined based on the final curing requirements, and the raw material source is the substrate from the previous treatment stages.

[0048] The implementation of these technical features enables solvent evaporation to proceed smoothly, the resin crosslinking reaction to proceed fully, and the inorganic phase condensation reaction to complete simultaneously through a staged, temperature-controlled curing method. This staged curing method helps reduce stress accumulation within the coating, avoids the formation of bubbles and cracks, and promotes the formation of a dense and complete coating structure, thereby improving the coating's bonding strength and durability.

[0049] In other technical solutions, before performing the coating treatment in step five, a latent curing agent is added to the mixed sol. The latent curing agent is a boron trifluoride-monoethylamine complex microcapsule coated with a polyurea shell. The shell melting temperature of the microcapsule is 140~160℃. The amount of the latent curing agent added is 2~5% of the total mass of epoxy resin in the mixed sol.

[0050] In the above technical solution, an electronic balance and sample container can be used as the main equipment in the selection and preparation of the latent curing agent. The microcapsules can be selected with a shell melting temperature of 150 degrees Celsius, and the mixed sol comes from the previous preparation process. The electronic balance should be placed on a shockproof test bench, and the sample container should be placed in the center of the balance's weighing pan. During the operation, an appropriate amount of microcapsules is weighed first, ensuring that its mass accounts for 3% of the total mass of epoxy resin in the mixed sol. Parameter settings are determined based on the activity of the curing agent, and the raw materials are sourced from a professional chemical supplier.

[0051] During the addition of the curing agent, a mechanical stirrer and a temperature control device can be used as the main equipment. Weighed microcapsules and a mixed sol are used as the main materials. The stirrer should be installed directly above the container, with the stirring paddle submerged to an appropriate depth below the liquid surface. During operation, the mixed sol is maintained at 25 degrees Celsius, and the microcapsules are slowly added while continuously stirring at a speed of 200 rpm for approximately 5 minutes. Parameter settings are determined based on the required dispersion uniformity, and the raw materials are sourced from the materials prepared in the preceding steps.

[0052] During subsequent mixing, a mechanical stirrer can be used in conjunction with a temperature monitoring device. The mixture system with the added curing agent is the target for processing. The temperature sensor should be inserted into the center of the mixture system, and the stirrer should rotate at a constant speed. During the process, continue stirring for 15 minutes after the addition is completed, maintaining the system temperature between 25 and 30 degrees Celsius to ensure uniform dispersion of the microcapsules. Parameter settings are adjusted according to changes in system viscosity, and the raw material source is the initial material of this process.

[0053] The implementation of these technical features enables phased control of the curing reaction during the coating curing process through the addition of a latent curing agent. The microcapsule shell melts and releases the curing agent at a specific temperature, allowing the crosslinking reaction to occur at an appropriate stage, which helps improve the controllability of the curing process and promotes the formation of a more complete network structure in the coating.

[0054] In other technical solutions, the boron trifluoride-monoethylamine complex microcapsules coated with a polyurea shell are prepared by the following method: Boron trifluoride-monoethylamine complex powder was dispersed in hexamethylene diisocyanate to form an oil phase; The emulsifier is dissolved in deionized water to form an aqueous phase; The oil phase is added to the aqueous phase under stirring conditions, with a mass ratio of oil phase to aqueous phase of 1:(3~5). The mixture is then subjected to high-speed shear emulsification at a speed of 10000~15000 rpm for 3~5 min to form an emulsion. An aqueous solution of ethylenediamine is slowly added dropwise to the emulsion, wherein the molar ratio of ethylenediamine to hexamethylene diisocyanate is 1:(1~1.2), and the reaction is carried out at 25~35°C for 4~6 h, thereby forming a polyurea shell on the surface of boron trifluoride-monoethylamine complex particles through interfacial polymerization. After the reaction was completed, the mixture was filtered, washed with deionized water, and dried under vacuum at 40-50°C to obtain the boron trifluoride-monoethylamine complex microcapsules coated with a polyurea shell.

[0055] In the above technical solution, in the initial stage of microcapsule preparation, a mechanical stirrer and glass container can be used as the oil phase preparation equipment, and a beaker and magnetic stirrer can be used as the aqueous phase preparation equipment. Boron trifluoride-monoethylamine complex powder can be of industrial grade, hexamethylene diisocyanate can be a chemically pure reagent, Span-80 or Tween-80 emulsifier can be used, and deionized water is commonly used in laboratories. The glass container should be placed on a stable surface in a fume hood, with the stir bar in the center of the container; the beaker should be placed on the heating plate of the magnetic stirrer, with the stir bar at the bottom of the beaker. During the operation, the boron trifluoride-monoethylamine complex powder and hexamethylene diisocyanate are first mixed in the glass container and stirred at 200 rpm for 10 minutes to form the oil phase; simultaneously, the emulsifier is dissolved in deionized water in the beaker and stirred at 150 rpm for 5 minutes to form the aqueous phase. The parameter settings are based on the requirement of dispersion uniformity, and the raw materials are sourced from chemical product suppliers.

[0056] In the emulsification and reaction stages, a high-speed shear emulsifier and a constant-temperature water bath can be used as the main equipment. The oil phase and aqueous phase come from the previous process, and the ethylenediamine can be an analytical grade reagent. The rotor of the emulsifier should be immersed to one-third of the mixed liquid surface, and the container of the water bath should be placed below the emulsifier. During operation, the oil phase is added to the aqueous phase at a rate of 50 ml per minute, while the emulsifier is started and sheared at 12,000 rpm for 4 minutes to form an emulsion. The emulsion is then transferred to the water bath, and the temperature is controlled at 30 degrees Celsius. An aqueous solution of ethylenediamine is added dropwise at a rate of 2 ml per minute, and the reaction continues for 5 hours after the addition is complete. The parameter settings are determined based on interfacial polymerization kinetics, and the raw materials are the aforementioned prepared materials.

[0057] In the post-processing stage, Buchner funnels, vacuum pumps, and vacuum drying ovens can be used as equipment. The post-reaction emulsion comes from the interfacial polymerization process, and deionized water is used as the washing solvent. The Buchner funnel should be connected to the vacuum pump and fixed to the filtration flask, and the sample trays in the drying oven should be evenly distributed. During the process, the post-reaction emulsion is first filtered and washed three times with deionized water, each time using twice the volume of the filter cake. Then, the filter cake is transferred to the vacuum drying oven and dried at 45 degrees Celsius for 6 hours. The parameter settings are based on the product moisture content requirements, and the raw material source is the initial material of this process.

[0058] The implementation of these technical features enables the preparation of microcapsules with polyurea shells via interfacial polymerization, achieving encapsulation and protection of the curing agent. The microcapsule shell melts and releases active ingredients at specific temperatures, helping to control the reaction timing during coating curing, reducing the risk of premature crosslinking, and promoting the formation of a more uniform network structure in the coating.

[0059] In some other technical solutions, the pretreatment process of the carbon steel substrate in step five includes the following steps: The surface of the carbon steel substrate is sandblasted using diamond abrasive with a particle size of 0.5~1.5 mm and a sandblasting air pressure of 0.5~0.8 MPa. After sandblasting, compressed air is used to blow away the substrate surface to remove residual abrasive dust. Subsequently, a two-stage solvent cleaning process was adopted, first wiping the substrate surface with petroleum ether, and then wiping the substrate surface with acetone. Finally, place the cleaned substrate in an oven at 80~100℃ and dry for 15~30 minutes. After removing it and cooling it to room temperature, apply the coating immediately.

[0060] In the above technical solution, a pressure sandblasting machine and an air compressor can be used as the main equipment during the substrate sandblasting process. The abrasive material can be 1.0 mm in diameter, and the carbon steel substrate can be Q235. The sandblasting gun should be kept 15 to 20 cm away from the substrate surface, and the air compressor outlet should be connected to the sandblasting machine via a pressure-resistant pipeline. During operation, the substrate is fixed on the operating table, and the sandblasting air pressure is adjusted to 0.6 MPa. The substrate surface is treated by uniform movement. Parameter settings are based on the substrate surface cleanliness and roughness requirements, and the raw materials are sourced from abrasive suppliers and the metal materials market.

[0061] In the surface cleaning stage, compressed air systems and non-woven fabric wiping materials can be used as the main tools. The substrate has undergone sandblasting, and industrial-grade solvents such as petroleum ether and acetone can be used. The compressed air nozzle should be held at a 45-degree angle to the substrate surface, and the wiping material must be kept clean. During the process, first use compressed air to blow away any residual abrasive particles from the surface, then wipe twice each with a non-woven fabric soaked in petroleum ether and acetone, allowing each solvent to completely evaporate after wiping. Parameter settings are determined based on the type of surface contaminants, and raw materials are sourced from chemical product suppliers.

[0062] In the drying process, a forced-air drying oven and sample rack can be used as the main equipment. The cleaned substrate is the object of treatment, requiring no additional materials. The sample rack in the drying oven should be placed horizontally, with the substrate maintaining an appropriate distance from the inner wall of the oven. During operation, the substrate is placed in the drying oven preheated to 90 degrees Celsius and maintained for 25 minutes. After removal, it is allowed to cool naturally at room temperature. Parameter settings are determined based on the moisture evaporation rate, and the raw material source is the substrate treated in the previous process.

[0063] The implementation of these technical features enables the effective removal of contaminants and oxide layers from the substrate surface through systematic surface pretreatment, resulting in suitable micro-roughness and providing a good bonding substrate for the coating. The treated substrate surface has a uniform roughness morphology and good chemical cleanliness, which helps to improve the mechanical and chemical adhesion between the coating and the substrate, creating favorable conditions for subsequent coating processes.

[0064] Example 1 A method for preparing an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating, the specific steps of which are as follows: First, the organosol was prepared. Silane coupling agent KH-560 and bisphenol A type epoxy resin were mixed at a mass ratio of 1:2, and propylene glycol methyl ether acetate solvent equivalent to three times the total mass of the two was added. The mixture was stirred at 300 rpm for 3 hours at 70°C to obtain a uniform and transparent organosol.

[0065] Next, the inorganic sol was prepared. Tetraethyl orthosilicate and propylene glycol methyl ether acetate were mixed at a volume ratio of 1:3, and deionized water was added, maintaining a molar ratio of deionized water to tetraethyl orthosilicate of 3:1. Hydrochloric acid with a concentration of 0.3 mol / L was added as a catalyst, and the mixture was allowed to stand at 30°C for 2 hours to hydrolyze, forming the inorganic sol.

[0066] For the pre-hybridization process, aluminum acetylacetonate was first added to the entire inorganic sol, at a rate of 1% of the total inorganic sol mass. The mixture was pre-aged at 45°C and 400 rpm for 1.5 hours to obtain a pre-catalyzed inorganic sol. Then, 15% of the total organic sol was slowly added to the pre-catalyzed inorganic sol under stirring, with the addition time controlled at 8 minutes, and the system temperature maintained at 35°C. This was followed by aging at 45°C and 400 rpm for 3 hours to obtain a pre-hybridized inorganic sol. Finally, the pre-hybridized inorganic sol and the remaining organic sol were stirred at 60°C and 200 rpm for 1.5 hours to complete the hybridization process.

[0067] The surface modification treatment of nanoparticles includes: dispersing zirconia nanoparticles with an average particle size of 30 nm in propylene glycol methyl ether acetate to form a suspension with a concentration of 80 g / L, and pre-ultrasonically dispersing at 400 W for 20 minutes. The suspension is then transferred to a reactor equipped with a reflux condenser, and silane coupling agent KH-560, equivalent to 5% of the mass of the zirconia nanoparticles, is added dropwise at a rate of 1.5 mL / min under stirring. The reaction is refluxed at 75 °C for 5 hours to obtain a modified zirconia nanoparticle suspension with epoxy functional groups grafted onto its surface.

[0068] The modified nanoparticles were post-treated: the suspension was centrifuged, the supernatant was removed, and a wet filter cake was obtained. Propylene glycol methyl ether acetate was added and redispersed to form a nanoparticle slurry with a solid content of 15%. The slurry was added to the hybrid sol at a rate of 1 mL per minute using a syringe pump, and then ultrasonically dispersed at 300 W for 45 minutes.

[0069] Before coating, a microencapsulation latent curing agent, equivalent to 3% of the total mass of epoxy resin, is added to the mixed sol. The microcapsules are prepared using hexamethylene diisocyanate as a raw material via interfacial polymerization, with a shell melting temperature of 150°C.

[0070] Substrate pretreatment includes: sandblasting Q235 carbon steel using 1.0 mm abrasive at a sandblasting pressure of 0.6 MPa. After sandblasting, the surface is first blown with compressed air, then wiped with petroleum ether and acetone in sequence. Finally, it is dried at 90°C for 20 minutes and cooled to room temperature.

[0071] High-pressure airless spraying equipment was used for coating, controlling the coating thickness to 35 micrometers. After coating, the coating was allowed to stand at room temperature for 20 minutes to allow the solvent to evaporate. The curing process used a programmed temperature increase: increasing the temperature at 1.5°C per minute to 90°C and holding for 30 minutes; increasing the temperature at 0.8°C per minute to 140°C and holding for 45 minutes; increasing the temperature at 2.5°C per minute to 200°C and holding for 2 hours.

[0072] The coating obtained by the above process has a smooth and dense surface, adheres firmly to the substrate, and exhibits excellent corrosion resistance in marine environments. The entire process is stable and controllable, with good compatibility among the components, achieving the design objectives.

[0073] Comparative Example 1 A traditional mixed solvent system was used for preparation. In the organic sol preparation stage, toluene was used as the solvent for the epoxy resin, while anhydrous ethanol was used as the solvent for the tetraethyl orthosilicate in the inorganic sol preparation stage. Specifically, the silane coupling agent and epoxy resin were dissolved in toluene at a mass ratio of 1:2, with the solvent volume being three times the total mass of both. The mixture was stirred at 70°C for 3 hours. In the inorganic sol preparation stage, tetraethyl orthosilicate and anhydrous ethanol were mixed at a volume ratio of 1:3, with other parameters identical to those in Example 1. Anhydrous ethanol was used as the dispersion medium during the nanoparticle modification process, and no solvent replacement treatment was performed. All other process parameters remained consistent with those in Example 1.

[0074] Comparative Example 2 A traditional one-step hybridization process is employed, completely omitting the pre-hybridization step. The specific operation is as follows: the organic sol and inorganic sol are directly mixed at a mass ratio of 1.5:1 and stirred at 60°C for 1.5 hours. No pre-catalytic treatment with aluminum acetylacetonate is performed, the organic sol is not added in stages, and no aging process is included. All other process conditions are the same as in Example 1, including the nanoparticle modification and curing process.

[0075] Comparative Example 3 A standard boron trifluoride-monoethylamine complex was directly added without microencapsulation. The specific procedure was as follows: the unencapsulated boron trifluoride-monoethylamine complex was directly added to the mixed sol, at an amount equivalent to 3% of the total mass of the epoxy resin. No microencapsulation was performed, and the curing process employed the same multi-stage temperature programmed heating regime as in Example 1. All other preparation processes remained consistent with Example 1.

[0076] The coating samples prepared in Example 1 and Comparative Examples 1-3 were used to evaluate the physical properties and corrosion resistance of the coatings using industry standard testing methods. The tests were conducted in a standard environment with a temperature of 25±2℃ and a relative humidity of 50±5%.

[0077] 1. Adhesion test (based on ASTM D3359 cross-cut adhesion test) Method: Draw a 1mm×1mm grid on the coating surface, apply 3M tape and then quickly peel it off. Rate the area of ​​coating peeling off (0B-5B, 5B indicates no peeling).

[0078] Data record: Adhesion rating (0-5B).

[0079] 2. Corrosion resistance test (based on ASTM B117 salt spray test) Method: The sample was placed in a salt spray chamber and sprayed continuously using a 5% NaCl solution at 35°C. The time when red rust appeared was checked and recorded periodically.

[0080] Data record: Time (in hours) at which the first matrix corrosion occurred.

[0081] 3. Mechanical property testing Impact resistance (according to ASTM D2794): using an impact testing machine with a 1kg hammer and a drop height of 50cm, record the maximum impact energy (kg·cm) that prevents the coating from cracking or peeling.

[0082] Flexibility (according to ASTM D522): Bend the sample around a tapered shaft (6 mm in diameter) and check for cracks on the coating surface.

[0083] Data recording: Impact resistance value (kg·cm), flexibility result (pass / fail).

[0084] 4. Electrochemical impedance spectroscopy test (according to ASTM G106) Method: After immersing the sample in 3.5% NaCl solution for 24 hours, the impedance was measured using an electrochemical workstation at a frequency range of 10 Hz. 5 Hz ~10 -2 Hz, amplitude 10mV. Record the impedance modulus |Z| at low frequency (0.01 Hz).

[0085] Data Recording: Impedance Modulus |Z| (Ω·cm) 2 ).

[0086] The test results are shown in Table 1.

[0087] Table 1 As shown in Table 1, Example 1, using a unified propylene glycol methyl ether acetate solvent, achieved an adhesion of 5B and a salt spray corrosion time of 1000 hours, significantly outperforming Comparative Example 1 (adhesion of 3B and corrosion time of 240 hours). This demonstrates that the unified solvent system effectively improves compatibility and adhesion, and increases corrosion resistance.

[0088] Example 1, after pre-hybridization treatment, achieved an impact resistance of 50 kg·cm and passed the flexibility test, while Comparative Example 2 (without pre-hybridization) only achieved an impact resistance of 25 kg·cm and failed the flexibility test. This verifies that stepwise hybridization promotes the uniform fusion of the two phases.

[0089] Example 1 uses microencapsulated curing agents and multi-stage curing to achieve an impedance modulus of 1×10⁻⁶. 9 Ω·cm 2 Furthermore, the coating was defect-free; in contrast, Comparative Example 3 (using a common curing agent) had an impedance modulus of only 1×10⁻⁶. 8 Ω·cm 2 This demonstrates that microencapsulation technology enables precise control of the curing reaction, reducing internal stress and defects.

[0090] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for preparing an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating, characterized in that, Includes the following steps: Step 1: Dissolve the silane coupling agent and epoxy resin in propylene glycol methyl ether acetate solvent. The mass ratio of silane coupling agent to epoxy resin is 1:(1~3). The amount of propylene glycol methyl ether acetate solvent is 2~4 times the total mass of silane coupling agent and epoxy resin. Stir and react at 60~80℃ for 2~4 h to form an organic sol. Step 2: Mix tetraethyl orthosilicate and propylene glycol methyl ether acetate at a volume ratio of 1:(2~4), add deionized water, the molar ratio of deionized water to tetraethyl orthosilicate is (2~4):1, and add hydrochloric acid as a catalyst, the concentration of hydrochloric acid is 0.1~0.5 mol / L, and let it stand at 25~40℃ for 1~3 h to hydrolyze and form an inorganic sol; Step 3: Mix the organic sol obtained in Step 1 with the inorganic sol obtained in Step 2 at a mass ratio of (1~2):1, and stir at 50~70℃ for 1~2 h to form an organic-inorganic hybrid sol. Step 4: Add nano-zirconia with an average particle size of 20-50 nm to the organic-inorganic hybrid sol obtained in Step 3. The amount added is 5-15% of the total mass of the organic-inorganic hybrid sol. Disperse the mixture using an ultrasonic disperser at a power of 200-400 W for 30-60 min to obtain a mixed sol. Step 5: Apply the mixed sol obtained in Step 4 to the surface of the pretreated carbon steel substrate using a high-pressure airless spraying device. The coating thickness is 20~50 μm. After coating, let it stand at room temperature for 10~30 min to allow the solvent to evaporate. Then place it in an oven and cure it at 80~250℃ for 2~5 h to form an organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating.

2. The method for preparing the organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating as described in claim 1, characterized in that, The mixing process in step three is as follows: Aluminum acetylacetone is added to all the inorganic sols prepared in step two, and the amount of aluminum acetylacetone added is 0.5-2% of the total mass of the inorganic sols. The sols are pre-aged at 40-50°C and 300-500 r / min for 1-2 h to obtain a pre-catalyzed inorganic sol. 10-20% of the total amount of the organic sol prepared in step one is slowly added to the precatalytic inorganic sol under stirring conditions for 5-10 minutes, and the system temperature is maintained at 30-40℃ during this stage. After completing the above steps, age the mixture at 40-50℃ and 300-500 r / min for 2-4 h to obtain the pre-hybridized inorganic sol. The pre-hybridized inorganic sol and the remaining organic sol from step one are stirred at 50-70°C and 150-300 r / min for 1-2 h to complete the mixing in step three, forming an organic-inorganic hybrid sol.

3. The method for preparing the organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating as described in claim 1, characterized in that, The nano-zirconia particles in step four are modified nano-zirconia with epoxy functional groups grafted onto their surface, and their preparation process is as follows: Zirconia nanoparticles were dispersed in propylene glycol methyl ether acetate to form a nanoparticle suspension with a concentration of 50-100 g / L, and then pre-ultrasonically dispersed at a power of 300-500 W for 15-30 min. The nanoparticle suspension was transferred to a reactor equipped with a mechanical stirrer and a reflux condenser. Under stirring conditions, 3-8% of the mass of the nano-zirconia particles was added dropwise with the silane coupling agent KH-560, and the dropping rate was controlled to be 1-2 mL / min. After the addition is complete, the reaction system is heated to 70-80℃ and refluxed for 4-6 hours to allow the silane coupling agent to be fully hydrolyzed and undergo a condensation reaction with the hydroxyl groups on the surface of the nano-zirconia particles, thus obtaining a modified nano-zirconia suspension with epoxy functional groups grafted on its surface.

4. The method for preparing the organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating as described in claim 3, characterized in that, After the modified nano-zirconia suspension with epoxy functional groups grafted onto its surface is prepared, the process further includes a post-treatment and controlled addition step, specifically: The modified nano-zirconia suspension with epoxy functional groups grafted on its surface was centrifuged and the supernatant was removed to obtain a modified nano-zirconia wet filter cake. Propylene glycol methyl ether acetate solvent is added to the wet filter cake to redisperse the modified nano-zirconia particles, forming a propylene glycol methyl ether acetate-based nanoparticle slurry with a solid content of 10-20%. The propylene glycol methyl ether acetate-based nanoparticle slurry was added to the organic-inorganic hybrid sol obtained in step three at a rate of 0.5-2 mL / min using a syringe pump under stirring conditions. Then, the sol was dispersed using an ultrasonic disperser at a power of 200-400 W for 30-60 min to uniformly disperse the nano-zirconia particles and obtain a mixed sol.

5. The method for preparing the organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating as described in claim 4, characterized in that, The curing process in step five is specifically as follows: After coating and allowing the substrate to stand, heat it to 80-100°C at a heating rate of 1-2°C / min, and hold it at this temperature for 20-40 minutes. Continue heating at a rate of 0.5~1℃ / min to 130~150℃, and hold at this temperature for 30~60 min; Heat to 150-250℃ at a heating rate of 2-3℃ / min, and hold at this temperature for 1-3 hours to complete curing.

6. The method for preparing the organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating as described in claim 5, characterized in that, Before performing the coating treatment in step five, a latent curing agent is added to the mixed sol. The latent curing agent is a boron trifluoride-monoethylamine complex microcapsule coated with a polyurea shell. The shell melting temperature of the microcapsule is 140~160℃. The amount of the latent curing agent added is 2~5% of the total mass of epoxy resin in the mixed sol.

7. The method for preparing the organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating as described in claim 6, characterized in that, The boron trifluoride-monoethylamine complex microcapsules coated with a polyurea shell were prepared by the following method: Boron trifluoride-monoethylamine complex powder was dispersed in hexamethylene diisocyanate to form an oil phase; The emulsifier is dissolved in deionized water to form an aqueous phase; The oil phase is added to the aqueous phase under stirring conditions, with a mass ratio of oil phase to aqueous phase of 1:(3~5). The mixture is then subjected to high-speed shear emulsification at a speed of 10000~15000 rpm for 3~5 min to form an emulsion. An aqueous solution of ethylenediamine is slowly added dropwise to the emulsion, wherein the molar ratio of ethylenediamine to hexamethylene diisocyanate is 1:(1~1.2), and the reaction is carried out at 25~35°C for 4~6 h, thereby forming a polyurea shell on the surface of boron trifluoride-monoethylamine complex particles through interfacial polymerization. After the reaction was completed, the mixture was filtered, washed with deionized water, and dried under vacuum at 40-50°C to obtain the boron trifluoride-monoethylamine complex microcapsules coated with a polyurea shell.

8. The method for preparing the organic-inorganic hybrid nano-ceramic marine heavy-duty anti-corrosion coating as described in claim 1, characterized in that, The pretreatment process of the carbon steel substrate in step five includes the following steps: The surface of the carbon steel substrate is sandblasted using diamond abrasive with a particle size of 0.5~1.5 mm and a sandblasting air pressure of 0.5~0.8 MPa. After sandblasting, compressed air is used to blow away the substrate surface to remove residual abrasive dust. Subsequently, a two-stage solvent cleaning process was adopted, first wiping the substrate surface with petroleum ether, and then wiping the substrate surface with acetone. Finally, place the cleaned substrate in an oven at 80~100℃ and dry for 15~30 minutes. After removing it and cooling it to room temperature, apply the coating immediately.

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