Composite treatment method for ship long-acting anti-corrosion and anti-fouling coating containing rust conversion agent

Abstract

The invention discloses a composite treatment method for a ship long-acting anti-corrosion and anti-fouling coating containing a rust conversion agent, and relates to the ship anti-corrosion and anti-fouling technology, the composite treatment method comprises the following steps: S1, pretreating the surface of a rusty base material of a ship to remove loose rust and oil stains; and S2, the surface of the pretreated base material is evenly coated with a rust conversion agent, the rust conversion agent comprises phosphoric acid, tannic acid and a gallate compound generated by glycidyl tertiary carboxylic ester and gallic acid through an epoxy ring-opening esterification reaction, and the rust conversion agent and the rust layer are subjected to a chemical reaction. According to the composite treatment method for the ship long-acting anti-corrosion and anti-fouling coating containing the rust conversion agent, the comprehensive performance of the ship coating is remarkably improved through an innovative technical path, a rust layer does not need to be thoroughly removed, the workload of pretreatment and the damage risk of a base material are reduced, and the service life of the ship coating is prolonged. Meanwhile, the reserved tight rust layer serves as a reaction carrier, so that the binding force of the coating and the base material is enhanced, and the uniformity and stability of reaction with the rust layer are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to ship anticorrosion and antifouling technology, in particular to a ship long-acting anticorrosion and antifouling coating composite treatment method containing a rust converter. BACKGROUND

[0002] As the core equipment of water transportation, ships are long-term served in complex water environments such as oceans and rivers. The surface of the base material is easily affected by multiple factors such as seawater corrosion, microbial attachment and wet-dry alternation, which leads to accelerated corrosion and decreased structural strength. At the same time, biofouling increases the sailing resistance and consumes more energy, so it is very important to effectively prevent corrosion and fouling of ships. At present, the industry generally adopts coating protection technology, which forms a functional coating system on the surface of the base material to block the intrusion of corrosive media and inhibit biological attachment. The synergistic effect of rust conversion, anticorrosion layer and antifouling layer is the key to improving the protection effect, and the optimization of related technology has always been the research focus in the field of ship protection.

[0003] In the existing ship coating protection technology, the rust layer needs to be completely removed in the pretreatment stage, which not only consumes time and effort, but also may damage the base material. The rust converter relies on a single component, and the uniformity and stability of the reaction with the rust layer need to be improved. The interface combination of the anticorrosion layer and the antifouling layer relies on physical adsorption, which is prone to delamination under long-term alternating stress and medium erosion, affecting the overall protection life. In addition, some coating systems are prone to cracking due to mismatched elastic modulus when the temperature changes sharply, making it difficult to balance the long-acting anticorrosion and antifouling performance. In view of this, we propose a ship long-acting anticorrosion and antifouling coating composite treatment method containing a rust converter. SUMMARY

[0004] To solve the above technical problems, a ship long-acting anticorrosion and antifouling coating composite treatment method containing a rust converter is provided. The technical solution solves the problems of complete rust removal in pretreatment, time and effort consumption and possible damage to the base material; single component of the rust converter, reaction uniformity and stability need to be improved; interface of anticorrosion and antifouling layer relies on physical adsorption, which is prone to delamination after long-term use; coating is prone to cracking due to mismatched elastic modulus under temperature change, making it difficult to balance the long-acting protection performance.

[0005] To achieve the above purposes, the technical solution adopted by the present application is as follows:

[0006] A ship long-acting anticorrosion and antifouling coating composite treatment method containing a rust converter, comprising the following steps:

[0007] S1, pretreating the rusted base material surface of the ship to remove loose rust and oil stains;

[0008] S2, uniformly coating a rust conversion agent on the pretreated substrate surface, the rust conversion agent comprising phosphoric acid, tannic acid and a gallate compound generated by ring-opening esterification reaction of glycidyl t- carbonate and gallic acid, the rust conversion agent chemically reacting with the rust layer;

[0009] S3, coating an anti-corrosion functional layer after curing the rust conversion layer, the anti-corrosion functional layer being composed of an epoxy resin and graphene;

[0010] S4, coating an anti-fouling functional layer after the anti-corrosion functional layer is dry, the anti-fouling functional layer being composed of an organic silicon polymer and nano-silica;

[0011] S5, controlling the interval time and curing conditions of each coating layer to form a chemical bonded interface between each layer, and finally forming a composite coating system comprising a rust conversion layer, an anti-corrosion functional layer and an anti-fouling functional layer.

[0012] Preferably, the surface pretreatment method in step S1 is specifically as follows:

[0013] A high-pressure water jet combined with mechanical polishing process is used, the water jet pressure ranges from 80 MPa to 120 MPa, and the mechanical polishing uses an alloy abrasive with a hardness of ≥HRC50;

[0014] The two-stage treatment is used to remove loose rust on the substrate surface with a thickness of >75 μm, while retaining a compact rust layer with a thickness of 0.05-0.15 mm as a rust conversion agent reaction carrier;

[0015] During the pretreatment process, compressed air is used to blow and remove the residual abrasive debris and rust powder on the surface, so as to ensure that the substrate surface is free of visible impurities.

[0016] Preferably, the rust conversion agent coating in step S2 uses an airless spraying process, the spraying pressure is 15-20 MPa, the coating amount is controlled to be 80-120 g / m², the mass ratio of phosphoric acid to tannic acid in the rust conversion agent is (2-4):1, the molar ratio of glycidyl t-carbonate to gallic acid is (3-6):1, and the addition amount of dodecylbenzenesulfonic acid as a catalyst is 0.03-0.07% of the total mass of the rust conversion agent;

[0017] After coating, curing is performed at an ambient temperature of 20-30°C and a relative humidity of ≤75% for 8-12 hours.

[0018] Preferably, the anti-corrosion functional layer in step S3 uses a two-component epoxy resin system:

[0019] The A component comprises a bisphenol A type epoxy resin with an epoxy equivalent weight of 180-200 g / eq and a graphene dispersion with a graphene content of 3-5 wt%;

[0020] The B component is cashew nut shell oil modified phenolic amine curing agent, the mass ratio of the two components is (4-6):1, the coating thickness is controlled at 80-120 μm, and the coating is cured at 5-40 ℃ for 24-48 hours after coating. The graphene forms a continuous two-dimensional sheet distribution in the coating.

[0021] Preferably, the anti-fouling functional layer in step S4 adopts a composite system of silicone acrylate polymer and nano-silica, the polymer molecular weight is 50000-80000 Da, the nano-silica particle size is 20-50 nm, the addition amount is 10-15% of the mass of the polymer, the coating thickness is 60-100 μm, and the coating is self-cured at room temperature for 7 days after coating to form a coating structure with a super slippery interface.

[0022] Preferably, the interface bonding between the rust conversion layer and the corrosion-resistant functional layer is enhanced by chemical bonding, specifically, the reaction product on the surface of the rust conversion layer and the epoxy group in the epoxy resin undergo coordination polymerization reaction to form a Fe-O-C bonding structure at the interface, and the bonding strength is detected by a pull test to be ≥5 MPa;

[0023] The bonding structure is verified by X-ray photoelectron spectroscopy analysis.

[0024] Preferably, a gradient transition structure is adopted between the corrosion-resistant functional layer and the anti-fouling functional layer, specifically, the anti-fouling functional layer is coated during the surface drying stage of the corrosion-resistant functional layer, so that the molecular chains of the silicone polymer in the anti-fouling functional layer penetrate into the surface of the corrosion-resistant functional layer to a depth of 5-10 μm, forming an interpenetrating network structure, and the interlayer adhesion is detected by a cross-hatch test to be ≥0 grade;

[0025] The structure is verified by observing the interface section through a scanning electron microscope.

[0026] Preferably, the total thickness of the composite coating system is controlled at 220-320 μm, and the thickness ratio of each layer is rust conversion layer: corrosion-resistant functional layer: anti-fouling functional layer = (1-2):(3-4):(2-3). By optimizing the elastic modulus matching of each layer material, the rust conversion layer is 1-3 GPa, the corrosion-resistant functional layer is 2-4 GPa, and the anti-fouling functional layer is 0.5-1 GPa, so that the coating system maintains structural integrity under temperature cycling from -20 ℃ to 80 ℃.

[0027] Preferably, the pretreatment of step S1 further includes adjusting the pH value of the substrate surface, using a sodium carbonate solution with a mass concentration of 5-10% to neutralize the substrate surface, so that the surface pH value is stabilized at 6.5-7.5. This adjustment step is performed after removing loose rust and oil stains and before coating the rust conversion agent. The surface acidity or alkalinity is detected by pH test paper or a portable pH meter.

[0028] Preferably, the coating control of the rust converter also includes stirring treatment of the rust converter before coating, the stirring rate is 300-500 r / min, the stirring time is 15-30 minutes, the stirring treatment ensures that the components in the rust converter are uniformly dispersed without precipitation or stratification phenomenon, and the dispersion effect is verified by monitoring the viscosity change of the rust converter by a viscometer.

[0029] Compared with the prior art, the beneficial effects of the present application are that:

[0030] The ship long-acting anticorrosive and antifouling coating composite treatment method containing the rust converter provided by the present application significantly improves the comprehensive performance of the ship coating through an innovative technical path, without the need to completely remove the rust layer, reduces the workload and substrate damage risk of pretreatment, and at the same time, the retained compact rust layer enhances the adhesion of the coating and the substrate as a reaction carrier, the multi-component synergistic effect in the rust converter improves the uniformity and stability of the reaction with the rust layer, ensures the rust conversion effect, the anticorrosive functional layer and the antifouling functional layer realize strong interface bonding through chemical bonding and gradient transition structure, effectively prevent interlayer separation, prolong the service life of the coating, and through optimization of the elastic modulus matching of each layer of material, the coating system can still maintain structural integrity under extreme temperature conditions, and the long-acting anticorrosive and antifouling performance is taken into account, providing more reliable protection for the ship. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The method flowchart of the present application is described. DETAILED DESCRIPTION

[0032] The following description is used to disclose the present application so that those skilled in the art can implement the present application. The preferred embodiments in the following description are only as examples, and other obvious modifications can be thought of by those skilled in the art.

[0033] REFERENCE Figure 1As shown, a long-acting anticorrosive and antifouling coating composite treatment method for ships containing a rust converter, the core of which is to build a multi-layer synergistic protective system, the whole process begins with the precise pretreatment of the surface of the ship with rusted substrate. This pretreatment uses high-pressure water jet combined with mechanical polishing process, in which the pressure of high-pressure water jet is strictly controlled in the range of 80 to 120 megapascal (MPa), and this pressure interval has been verified to be effective in peeling off large loose rust without damaging the substrate body; mechanical polishing selects alloy abrasive with hardness not less than Rockwell hardness (HRC) 50 to ensure sufficient cutting force. Through these two levels of processing, the goal is to remove the loose rust layer of more than 75 microns (μm) on the surface of the substrate, while deliberately retaining a layer of dense rust layer with a thickness of 0.05 to 0.15 millimeters (mm), which will serve as a key carrier for the subsequent rust converter chemical reaction. During the pretreatment process, it is essential to use compressed air to blow away the surface of the residual abrasive debris and rust powder, which is to ensure that the surface of the substrate reaches a state of no visible impurities, providing a clean base for coating adhesion. Then, after removing loose rust and oil, an important surface pH adjustment step is added before applying the rust converter, that is, using a sodium carbonate solution with a mass concentration of 5% to 10% to neutralize the surface of the substrate, and the surface pH is confirmed to be stable between 6.5 and 7.5 by pH test paper or portable pH meter, which aims to eliminate any potential acid-base residues that interfere with the reactivity of the rust converter.

[0034] After the pretreatment, the rust conversion coating process (S2) is performed. Before coating, the rust conversion coating is stirred at a rate of 300 to 500 revolutions per minute (r / min) for 15 to 30 minutes to ensure that the components of different densities and polarities (especially phosphoric acid and other components) are uniformly dispersed, avoiding precipitation or stratification. The stirring effect can be verified by monitoring the viscosity change. The coating is performed using an airless spraying process at a pressure of 15 to 20 megapascals (MPa), which ensures good atomization and effective penetration of the rust conversion coating into the remaining dense rust layer micro-pore structure. The coating amount is accurately controlled at 80 to 120 grams per square meter (g / m²). The formula of the rust conversion coating is one of the technical cores, which includes phosphoric acid, tannic acid, and a specific gallic acid ester compound generated by the epoxy ring-opening esterification reaction of glycidyl ester of tertiary carbonic acid and gallic acid. The mass ratio of phosphoric acid to tannic acid is set at (2-4):1, which is based on the optimized synergistic effect between the strong rust removal ability of phosphoric acid and the chelation and stabilization effect of tannic acid on iron ions. The molar ratio of glycidyl ester of tertiary carbonic acid to gallic acid is set at (3-6):1, which is optimized through experiments to ensure that the ring-opening esterification reaction proceeds sufficiently, generating sufficient amount of target ester compounds, giving the coating good toughness and adhesion. Dodecylbenzenesulfonic acid is used as a high-efficiency catalyst, and its addition amount is accurately controlled at 0.03% to 0.07% of the total mass of the rust conversion coating, which can effectively catalyze the reaction and avoid introducing too many impurities to affect the performance of the coating. The coated rust conversion layer needs to be cured at an ambient temperature of 20 to 30 degrees Celsius (℃) and a relative humidity of not more than 75% for 8 to 12 hours, which is conducive to the complete chemical reaction between the rust layer and the components of the rust conversion coating, forming a stable conversion layer.

[0035] After the rust layer is fully cured, the anticorrosion functional layer (S3) is coated. The layer uses a high-performance two-component epoxy resin system. The A component contains a standard bisphenol A type epoxy resin with an epoxy equivalent weight of 180 to 200 grams equivalent (g / eq), and a pre-prepared graphene dispersion with a graphene content of 3% to 5% by weight percentage (wt%). The B component selects a cashew shell oil modified phenolic amine curing agent. The mixing mass ratio of A component to B component is strictly controlled at (4-6): 1, which can ensure that the epoxy groups and amine groups are fully cross-linked and cured. The coating thickness is controlled at 80 to 120 microns (μm). After coating, the anticorrosion functional layer is cured for 24 to 48 hours in a wide temperature range (5 to 40°C), which takes into account the temperature fluctuations of the actual shipyard construction environment. During this process, by optimizing the dispersion process (such as high-speed shearing, ultrasonic treatment, etc.) and the viscosity of the resin system, it is ensured that the added graphene can form a uniform, continuous and highly oriented two-dimensional sheet distribution structure in the cured coating, which is the key to giving the coating excellent barrier properties (blocking water, oxygen, electrolyte penetration) and enhanced mechanical strength.

[0036] When the anticorrosion functional layer reaches the surface dry state (i.e. the surface has been preliminarily cured but the interior still has certain permeability), the antifouling functional layer (S4) is immediately coated. The layer uses a composite system of silicone acrylate polymer (molecular weight range 50000 to 80000 Daltons (Da)) and nano-silica (particle size 20 to 50 nanometers (nm)). The addition amount of nano-silica is 10% to 15% of the mass of silicone polymer, which is optimized to maximize its role in enhancing and reducing surface energy while ensuring good dispersion. The coating thickness is 60 to 100 microns (μm). After coating, the antifouling functional layer is self-cured at room temperature for 7 days, finally forming an ultra-smooth interface coating structure with low surface energy, high surface flatness and excellent hydrophobicity, which can effectively prevent the attachment of marine biofouling.

[0037] The precise control of the coating interval time and curing conditions of each coating layer (S5) is the key to ensure the formation of a strong and tough chemical bonding interface in the multi-layer coating system throughout the entire process. Specifically, between the rust conversion layer and the corrosion protection functional layer, the chemical reaction products on the surface of the rust conversion layer (such as iron phosphate, tannic acid iron complex, and ester compounds) can undergo a specific coordination polymerization reaction with the epoxy groups (-CH(O)CH-) in the subsequently coated epoxy resin, forming a stable Fe-O-C chemical bonding structure at the interface. This bonding significantly enhances the interlayer bonding strength, which is not less than 5 megapascals (MPa) as detected by standard pull-off testing, and the bonding structure can be clearly verified by X-ray photoelectron spectroscopy (XPS) analysis of the chemical state of the elements in the interface region (such as the binding energy and peak shape of Fe2p, O1s, C1s spectral peaks). Between the corrosion protection functional layer and the anti-fouling functional layer, a gradient transition structure design strategy is adopted: taking advantage of the fact that the surface molecular chains of the corrosion protection functional layer still have a certain activity when the surface is dry, the anti-fouling functional layer is coated in time, allowing the silicone polymer molecular chains in the anti-fouling functional layer to partially penetrate into the surface of the corrosion protection functional layer to a depth of 5 to 10 micrometers (μm). In this area, the silicone polymer and the epoxy resin molecular chains that have not yet fully crosslinked and cured are intertwined, ultimately forming an interpenetrating polymer network (IPN) structure. This microstructure greatly improves the interlayer adhesion, which can reach the highest level (≥0 grade, i.e., no peeling or falling off) as tested by the standard crosshatch adhesion test, and the formation of this interpenetrating network structure can be clearly verified by observing the cross-sectional morphology of the coating system interface using high-resolution scanning electron microscopy (SEM).

[0038] The final composite coating system is composed of a rust conversion layer, a corrosion protection functional layer, and an anti-fouling functional layer, with a total thickness controlled between 220 and 320 micrometers (μm). The thickness ratio of each layer is optimally set as rust conversion layer: corrosion protection functional layer: anti-fouling functional layer = (1-2):(3-4):(2-3). To ensure the structural integrity of the multi-layer system under the harsh environment faced by ships in service, especially the repeated temperature cycles from -20°C to 80°C, and to avoid cracking or peeling due to large differences in the thermal expansion coefficients of the materials in each layer, the elastic modulus of each functional layer is carefully matched and designed: the elastic modulus of the rust conversion layer is controlled at 1 to 3 gigapascals (GPa), the corrosion protection functional layer is 2 to 4 gigapascals (GPa), and the outermost anti-fouling functional layer is designed to be relatively low at 0.5 to 1 gigapascal (GPa). This design of decreasing modulus gradient from the inside to the outside can effectively buffer and disperse the internal stress caused by temperature changes, maintaining the long-term stability and protective effect of the entire coating system.

[0039] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only the principles of the present application. Various changes and improvements can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A long-lasting anticorrosive and antifouling coating composite treatment method for a ship containing a rust conversion agent, characterized by, The method comprises the following steps: S1, pretreating the rusted surface of the ship to remove loose rust and oil; S2, uniformly applying a rust conversion agent to the pretreated surface of the substrate, the rust conversion agent comprising phosphoric acid, tannic acid, and a gallate compound generated by the ring-opening esterification reaction of glycidyl ester of tertiary carbonic acid and gallic acid, the rust conversion agent chemically reacting with the rust layer; S3, applying an anti-corrosion functional layer after the rust layer is cured, the anti-corrosion functional layer being composed of epoxy resin and graphene; S4, applying an anti-fouling functional layer after the anti-corrosion functional layer is surface dried, the anti-fouling functional layer being composed of a composite system of silicone polymer and nano-silicon dioxide; S5, controlling the interval time and curing conditions of each coating to form a chemically bonded interface between each layer, and finally forming a composite coating system comprising a rust conversion layer, an anti-corrosion functional layer, and an anti-fouling functional layer.

2. The long-term anticorrosive and antifouling coating composite treatment method for a ship containing a rust conversion agent according to claim 1, characterized by, The specific method for surface pretreatment in step S1 is as follows: A high-pressure water jet combined with mechanical polishing process is used, the water jet pressure ranges from 80 MPa to 120 MPa, and the mechanical polishing uses alloy abrasives with a hardness of greater than or equal to HRC 50; Two-stage processing is used to remove loose rust of greater than 75 μm on the surface of the substrate, while retaining a tight rust layer with a thickness of 0.05-0.15 mm as a reaction carrier for the rust conversion agent; During the pretreatment process, compressed air is used to blow and remove the residual abrasive debris and rust powder on the surface, so as to ensure that the surface of the substrate is free of visible impurities.

3. The long-term anticorrosive and antifouling coating composite treatment method for ships containing a rust conversion agent according to claim 1, characterized by, In step S2, the rust conversion agent is applied by using an airless spraying process, the spraying pressure is 15-20 MPa, the coating amount is controlled to be 80-120 g / m2, the mass ratio of phosphoric acid to tannic acid in the rust conversion agent is (2-4):1, the molar ratio of glycidyl ester of tertiary carbonic acid to gallic acid is (3-6):1, and the addition amount of dodecylbenzenesulfonic acid as a catalyst is 0.03-0.07% of the total mass of the rust conversion agent; After application, curing is performed at an ambient temperature of 20-30 °C and a relative humidity of less than or equal to 75% for 8-12 hours.

4. The long-term anti-corrosion and anti-fouling coating composite treatment method for ships containing a rust conversion agent according to claim 1, characterized in that, In step S3, the anti-corrosion functional layer is composed of a two-component epoxy resin system: The A component comprises bisphenol A type epoxy resin with an epoxy equivalent weight of 180-200 g / eq and graphene dispersion with a graphene content of 3-5 wt%; The B component is cashew nut shell oil modified phenolic amine curing agent, the mass ratio of the two components is (4-6):1, the coating thickness is controlled to be 80-120 μm, and after application, curing is performed at an ambient temperature of 5-40 °C for 24-48 hours, and the graphene forms a continuous two-dimensional sheet distribution in the coating.

5. The long-term anticorrosive and antifouling coating composite treatment method for ships containing a rust conversion agent according to claim 1, characterized by, In step S4, the anti-fouling functional layer is composed of a composite system of silicone acrylate polymer and nano-silicon dioxide, the polymer has a molecular weight of 50,000-80,000 Da, the nano-silicon dioxide has a particle size of 20-50 nm, the addition amount of the nano-silicon dioxide is 10-15% of the mass of the polymer, the coating thickness is 60-100 μm, and after application, self-curing is performed at room temperature for 7 days to form a coating structure with a super-smooth interface.

6. The long-term anti-corrosion and anti-fouling coating composite treatment method for ships containing a rust conversion agent according to claim 1, characterized in that, The rust conversion layer and the anti-corrosion functional layer are chemically bonded to enhance the interface bonding, specifically, the reaction products on the surface of the rust conversion layer and the epoxy groups in the epoxy resin undergo coordination polymerization to form a Fe-O-C bonding structure at the interface, and the bonding strength is greater than or equal to 5 MPa as detected by a pull-out test. The bonding structure is verified by X-ray photoelectron spectroscopy analysis.

7. The long-term anti-corrosion and anti-fouling coating composite treatment method for ships containing a rust conversion agent according to claim 1, characterized in that, The gradient transition structure is adopted between the anti-corrosion functional layer and the anti-fouling functional layer, specifically, the anti-fouling functional layer is coated in the surface drying stage of the anti-corrosion functional layer, so that the molecular chain of the silicone polymer of the anti-fouling functional layer penetrates into the surface of the anti-corrosion functional layer to a depth of 5-10 μm, forming an interpenetrating network structure, and the interlayer adhesion is detected by the grid test to be ≥0 grade; The structure is verified by scanning electron microscope observation of the interface section.

8. The long-term anti-corrosion and anti-fouling coating composite treatment method for ships containing a rust conversion agent according to claim 1, characterized in that, The total thickness of the composite coating system is controlled to be 220-320 μm, and the thickness ratio of each layer is rust conversion layer: anti-corrosion functional layer: anti-fouling functional layer = (1-2):(3-4):(2-3), by optimizing the elastic modulus matching of each layer material, the rust conversion layer is 1-3 GPa, the anti-corrosion functional layer is 2-4 GPa, and the anti-fouling functional layer is 0.5-1 GPa, so that the coating system maintains structural integrity under temperature cycles of-20℃ to 80℃.

9. The long-term anti-corrosion and anti-fouling coating composite treatment method for ships containing a rust conversion agent according to claim 1, characterized in that, The pretreatment of step S1 also includes adjusting the pH value of the substrate surface, using a sodium carbonate solution with a mass concentration of 5-10% to neutralize the substrate surface, so that the surface pH value is stable between 6.5-7.5, the adjustment step is carried out after removing loose rust and oil stains, and before coating the rust conversion agent, the surface acidity or alkalinity is detected by pH test paper or portable pH meter.

10. The long-term anticorrosive and antifouling coating composite treatment method for a ship containing a rust conversion agent according to claim 1, characterized by, The coating control of the rust conversion agent also includes stirring the rust conversion agent before coating, the stirring rate is 300-500 r / min, and the stirring time is 15-30 minutes, so as to ensure that each component in the rust conversion agent is uniformly dispersed without precipitation or stratification phenomenon, and the dispersion effect is verified by monitoring the viscosity change of the rust conversion agent by a viscometer.

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