Composite anticorrosive coating material, its coating method and application

Abstract

The application discloses a composite anticorrosive coating, a coating method and application thereof, and belongs to the technical field of anticorrosive coatings.The composite anticorrosive coating comprises a first component, a second component and a third component in a weight ratio of (0.01-0.05):1:(0.2-0.3), wherein the first component is a lanthanide metal nitrate solution; the second component comprises: 1 part of epoxy resin or epoxy phenolic resin, 0.02-0.07 parts of a corrosion control component, 1.35-2.0 parts of pigments and fillers, 0.02-0.03 parts of a defoaming agent, 0.01-0.02 parts of a dispersing agent and 0.01-0.02 parts of a leveling agent; and the third component is an epoxy curing agent.The composite anticorrosive coating provided by the application can react with water to generate a precipitated protective film layer of Ln 3+ -Zn 2+ -SiO3 2‑ in a corrosive environment, so as to effectively isolate the composite anticorrosive coating from corrosive media and compensate for the physical micropinhole defects of the coating, and common problems in the application of organic resin coatings in high-corrosive oil-water media are effectively overcome.

Description

Technical Field

[0001] This invention relates to the field of coating protection technology, specifically to a composite anti-corrosion coating and its coating method and application. Background Technology

[0002] Conventional two-component coating formulations typically consist of component one, which is formed by adding fillers, leveling agents, and defoamers to epoxy resins, epoxy phenolic resins, etc., and component two, which is an epoxy curing agent. Before coating, the two components are mixed and cured in proportion, and then applied to the surface of the object to be protected.

[0003] Commonly used fillers include calcium carbonate, barite powder, talc powder, kaolin, porous quartz powder (silicon dioxide), white carbon black, precipitated barium sulfate, and mica powder. This is to reduce the amount of alkali used in the resin, thereby lowering production costs, and also to enhance the chemical properties of the coating, such as rust prevention, moisture resistance, and flame retardancy.

[0004] In addition, it has been found that some metals, such as zinc, can be added to primers to help improve the corrosion resistance of the coating. When the coating performs its corrosion-resistant function, metals like zinc can act as sacrificial anode materials to protect the steel or iron substrate that becomes the cathode.

[0005] For example, CN104603213A discloses a zinc-containing anti-corrosion primer composition comprising a silicate / ester-based binder system, zinc particles, hollow glass microspheres, and conductive pigments. This patent aims to improve corrosion resistance in a cost-effective manner and by limiting the amount of zinc added.

[0006] CN106068310A also proposed a scheme to add zinc particles to various adhesive systems.

[0007] CN104745044A discloses a zinc-rich primer using an activation technology, in which zinc powder is added to the matrix resin.

[0008] In addition, high-content zinc powder (generally >70%) is added to organic zinc-based epoxy zinc-rich coatings to improve performance, including (1) the overlapping or overlapping of flake or powder zinc powder, which increases the penetration distance of corrosive media; (2) zinc acts as a sacrificial anode in the surface contact between iron and zinc; (3) zinc reacts with corrosive media to generate basic zinc carbonate, zinc oxide, etc., which block micropores or damaged areas of the coating and can achieve self-healing to a certain extent. However, there are also problems such as the impact on coating density and adhesion and increased cost when the zinc powder content is too high. Moreover, in traditional coating formulations, fillers and zinc powder mainly react chemically with the corrosive media that penetrate into the coating, playing an auxiliary role. They do not have a synergistic effect.

[0009] Existing technologies, such as Zhang Yanjun et al.'s paper "Research on Fluororubber Anticorrosion Coatings" (Coatings Industry, 2005, No. 10), introduce the functions of each component of the coating. Bian Jie et al., in "Research Progress of Organic Coatings for Metal Corrosion Protection" (Journal of Materials Science and Engineering, 2003, No. 85), describe that "surface protection can be divided into four types: 1. Applying organic coatings to metal surfaces; 2. Plating corrosion-resistant metal or alloy layers on metal surfaces; 3. Changing the composition of the metal surface layer; 4. Forming a chemical conversion film on the metal surface. Among them, organic coating protection involves applying corrosion-resistant organic coatings to the metal surface, which, after curing into a film, has three functions: shielding, corrosion inhibition, and electrochemical protection. It is widely used due to its convenient construction and good anticorrosion effect." However, there are no reports on organic coatings that combine the functions of metal surface modification and organic coating modification.

[0010] Chinese patents CN111675928A ("A Two-Component Carbon Nanotube Type Epoxy Zinc-Rich Coating") describes a carbon nanotube-containing epoxy zinc-rich coating; CN108117816A ("A Nano-Modified Epoxy Zinc-Rich Coating") describes a nano-zinc oxide-modified epoxy coating; and CN110054967B ("A High-Performance, Low-Zinc Content Epoxy Zinc-Rich Coating and Its Preparation Method") describes a method to improve the corrosion resistance of coatings by replacing zinc powder with Mn powder and manganese phosphate powder. However, most of these patents are based on coating modification methods that reduce or replace zinc powder content or improve the properties of zinc powder itself. They do not address composite coating systems that combine zinc powder and other additives with metal surface modification, nor do they address the secondary corrosion-inhibiting synergistic effect of the modified components, zinc powder, and other additives formed by ionization after the corrosive medium solution penetrates the coating. Summary of the Invention

[0011] To address the problems of high zinc powder content and high cost in organic zinc coatings containing zinc powder, as well as the lack of synergistic corrosion inhibition effects among modified components, fillers, and zinc powder in traditional coating formulations, the present invention aims to: 1) provide a composite anti-corrosion coating; 2) provide a coating method for the composite anti-corrosion coating; and 3) provide applications for the composite anti-corrosion coating.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A composite anti-corrosion coating comprises a first component, a second component, and a third component in a weight ratio of (0.01–0.05):1:(0.2–0.3), wherein:

[0014] The first component is a lanthanide metal nitrate solution;

[0015] The second component comprises the following raw materials in parts by weight: 1 part epoxy resin or epoxy phenolic resin, 0.02 to 0.07 parts corrosion control component, 1.35 to 2.0 parts pigments and fillers, 0.02 to 0.03 parts defoamer, 0.01 to 0.02 parts dispersant and 0.01 to 0.02 parts leveling agent;

[0016] The third component is an epoxy curing agent.

[0017] Furthermore, the molecular formula of the lanthanide metal nitrate solution is Ln(NO3)3·nH2O, where n = 5 to 7, and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, or Tm.

[0018] Preferably, the concentration of the lanthanide nitrate solution is 0.1% to 30%.

[0019] As a further optimization and / or improvement of the present invention, the corrosion control component comprises, by weight, the following components: 0.01 to 0.02 parts of zinc powder and 0.01 to 0.05 parts of sodium silicate powder.

[0020] As a further optimization and / or improvement of the present invention, the zinc powder is flake-shaped with a fineness of <30 μm and a zinc content of >96%; the sodium silicate powder is spherical, needle-shaped, or fibrous with a fineness of 0.01–20 μm.

[0021] As a further optimization and / or improvement of the present invention, the pigments and fillers, by weight, comprise the following components: 0.6 to 0.75 parts barium sulfate, 0.2 to 0.35 parts talc, 0.25 to 0.3 parts wollastonite, 0.3 to 0.45 parts mica, and 0.003 to 0.005 parts fumed silica.

[0022] As a further optimization and / or improvement of the present invention, the epoxy curing agent comprises, by weight, 1 part modified aromatic amine curing agent and 0.8 to 1 part phenolic curing agent.

[0023] As a further optimization and / or improvement of the present invention, the second component is prepared by mixing 1 part by weight of epoxy resin or epoxy phenolic resin, 0.02-0.03 parts by weight of defoamer, 0.01-0.02 parts by weight of dispersant and 0.01-0.02 parts by weight of leveling agent evenly, adding 1.35-2.0 parts by weight of pigments and fillers under stirring conditions, mixing evenly and grinding, and then adding 0.02-0.07 parts by weight of corrosion control component and dispersing evenly to obtain the second component.

[0024] This invention also provides a method for applying a composite anti-corrosion coating, comprising the following steps:

[0025] S1, clean the surface of the steel substrate, sandblast or shot blast to remove rust, the rust removal grade reaches 2.5a, and the surface anchor texture is controlled at 40~60um;

[0026] S2, Lanthanide metal nitrate solution is sprayed onto the surface of the steel substrate multiple times until the film thickness on the tube surface reaches 10-20 μm after drying.

[0027] S3, Preparation of mixed coatings;

[0028] S4 involves applying resin coating to the surface of the pipe body of S2 once or multiple times by brushing or spraying until a composite anti-corrosion coating with a thickness of 100-200 μm is formed after curing.

[0029] Further, the mixed coating comprises a second component and a third component. The second component comprises the following raw materials in parts by weight: 1 part epoxy resin or epoxy phenolic resin, 0.02-0.07 parts corrosion control component, 1.35-2.0 parts pigments and fillers, 0.02-0.03 parts defoamer, 0.01-0.02 parts dispersant, and 0.01-0.02 parts leveling agent; the third component is an epoxy curing agent.

[0030] The preparation method of the mixed coating is as follows: the second component and the third component are mixed at a weight ratio of 1:(0.2 to 0.3), stirred evenly, and matured for 20 to 40 minutes to form a mixed coating.

[0031] Furthermore, in step S2, the drying method is natural drying or low-temperature drying, wherein the temperature of low-temperature drying is 20-60℃;

[0032] After applying the mixed coating once or multiple times in step S4, it is preferable to use room temperature curing or low temperature heating curing, with the temperature of low temperature heating curing controlled below 60°C.

[0033] The reaction mechanism of this invention is as follows:

[0034] The first component forms a dense lanthanide nitrate film on the surface of the steel substrate, serving as a surface modification agent; the second and third components form a resin layer with low zinc and sodium silicate content on the surface of the steel substrate; and the first component layer and the resin layer can be tightly bonded to each other, and can also form Ln during the corrosion process in a corrosive medium environment. 3+ -Zn 2+ -SiO3 2- Precipitated protective film layer, free Ln 3+ Zn 2+ It also has the effect of killing and inhibiting corrosive bacteria such as sulfate-reducing bacteria (SRB), producing a secondary antiseptic and bactericidal aftereffect.

[0035] The advantages of the present invention by adopting the above technical solution are as follows:

[0036] 1. The composite anti-corrosion coating provided by this invention involves spraying a lanthanide metal nitrate solution onto a clean steel substrate surface during the coating process, followed by applying a mixed coating of the second and third components onto the steel substrate surface using a brush or spray method. After curing, a composite anti-corrosion coating is formed. This composite anti-corrosion coating can form a thin and dense Fe-Ln(NO3)3 metal salt protective layer and an organic resin layer on the carbon steel surface.

[0037] 2. In corrosive media, the zinc powder and sodium silicate in the coating will become ionic, and in environments containing Ln... 3+ In this environment, the added Zn 2+ -SiO3 2- With Ln 3+ The combination has a significant inhibitory effect on the corrosion of carbon steel.

[0038] 3. In a corrosive environment, the effective components of the composite anti-corrosion coating provided by this invention will react with water to generate Ln. 3+ —Zn 2+ —SiO3 2- The precipitation-type protective film layer ensures that the composite anti-corrosion coating effectively isolates corrosive media and compensates for the physical micro-pinhole defects of the coating, effectively overcoming the common problems of organic resin coatings in highly corrosive oil and water media.

[0039] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0040] The invention can be further understood in conjunction with the following detailed description of preferred embodiments and included examples. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. If any definition of a specific term disclosed in the prior art differs from any definition provided herein, the definition provided herein shall prevail.

[0041] It should be noted that the implementation conditions used in the examples can be further adjusted according to the specific experimental environment, and the implementation conditions not specified are usually those in conventional experiments. Unless otherwise specified, the preparation methods mentioned in this invention are all conventional methods; all chemical reagents and chemicals mentioned in the following examples can be obtained from publicly available commercial sources unless otherwise specified.

[0042] This invention provides a composite anti-corrosion coating comprising a first component, a second component, and a third component in a weight ratio of (0.01–0.05):1:(0.2–0.3), wherein:

[0043] The first component is a lanthanide metal nitrate solution;

[0044] The second component comprises the following raw materials in parts by weight: 1 part epoxy resin or epoxy phenolic resin, 0.02 to 0.07 parts corrosion control component, 1.35 to 2.0 parts pigments and fillers, 0.02 to 0.03 parts defoamer, 0.01 to 0.02 parts dispersant and 0.01 to 0.02 parts leveling agent;

[0045] The third component is an epoxy curing agent.

[0046] Furthermore, the molecular formula of the lanthanide metal nitrate solution is Ln(NO3)3.nH2O, where n = 5 to 7, and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, or Tm.

[0047] To avoid excessively high concentrations of the metal nitrate solution, which could cause salt formation on the surface and affect adhesion, the present invention further preferably uses a lanthanide metal nitrate solution concentration of 0.1% to 30%.

[0048] As a further optimization of the above-mentioned technical solution of the present invention, the corrosion control component, by weight, includes the following components: 0.01-0.02 parts zinc powder and 0.01-0.05 parts sodium silicate powder. When water penetrates into the pinholes of the coating, zinc, sodium silicate, and lanthanide nitrates become ionic, and the three together passivate and form a film. Furthermore, zinc ions and silicate ions have a secondary bactericidal effect.

[0049] As a further optimization of the above-mentioned technical solution of the present invention, the zinc powder is flake-shaped with a fineness of <30 μm and a zinc content of >96%; the sodium silicate powder is spherical, needle-shaped or fibrous with a fineness of 0.01 to 20 μm.

[0050] As a further optimization of the above-mentioned technical solution of the present invention, the pigments and fillers, by weight, include the following components: 0.6-0.75 parts barium sulfate, 0.2-0.35 parts talc powder, 0.25-0.3 parts wollastonite powder, 0.3-0.45 parts mica powder, and 0.003-0.005 parts fumed silica.

[0051] The defoamer is mainly composed of a mixture of defoaming polysiloxane and hydrophobic particles in polyethylene glycol. Specifically, preferred defoamers include BYK-190 and BYK-024 from BYK GmbH (Germany) and MEM-0349 from Dow Corning. The defoamer reduces the surface tension of the coating during its formation, preventing foam formation.

[0052] The main component of the dispersant is an ammonium alkoxide solution of a multifunctional polymer. Specifically, preferred dispersants include BYK-163 from BYK GmbH (Germany) and Evonik E525 from Evonik GmbH. Dispersants prevent particle settling and agglomeration during coating formation.

[0053] The main component of leveling agents is an ionic polyacrylate solution. Specifically, preferred leveling agents include BYK-358N from BYK GmbH (Germany) and 4358 from Yichen Chemical. Leveling agents promote the formation of a smooth, uniform film during the drying process of coatings, effectively reducing the surface tension of the coating liquid and improving its leveling and uniformity.

[0054] As a further optimization of the above-mentioned technical solution of the present invention, the epoxy curing agent, by weight, comprises 1 part modified aromatic amine curing agent and 0.8 to 1 part phenolic curing agent. The modified aromatic amine curing agent exhibits excellent heat resistance and chemical resistance; preferably, it is a curing agent produced by Guodu Chemical Co., Ltd., product models TH-430, TH-431, and TH-452N. The phenolic curing agent can increase the crosslinking density of the coating, thereby improving the adhesion and corrosion resistance of the coating; preferably, it is a phenolic curing agent produced by Guodu Chemical Co., Ltd., product models KD-401, KD-426, and KD-410A. The epoxy modified aromatic amine curing agent and phenolic curing agent of the present invention enable the coating to possess, in addition to the advantages of good chemical stability, heat resistance, acid resistance, alkali resistance, and wear resistance of traditional solvent-based epoxy coatings, also good flexibility and impact resistance.

[0055] As a further optimization of the above-mentioned technical solution of the present invention, the preparation method of the second component is as follows: 1 part by weight of epoxy resin or epoxy phenolic resin, 0.02-0.03 parts by weight of defoamer, 0.01-0.02 parts by weight of dispersant and 0.01-0.02 parts by weight of leveling agent are mixed evenly, 1.35-2.0 parts by weight of pigments and fillers are added under stirring, the mixture is ground evenly, and then 0.02-0.07 parts by weight of corrosion control component is added and dispersed evenly to obtain the second component.

[0056] This invention further protects a coating method for a composite anti-corrosion coating, comprising the following steps:

[0057] S1, clean the surface of the steel substrate, sandblast or shot blast to remove rust, the rust removal grade reaches 2.5a, and the surface anchor texture is controlled at 40~60um;

[0058] S2, Lanthanide metal nitrate solution is sprayed repeatedly onto the surface of the treated steel substrate until the film thickness on the tube surface reaches 10-20 μm after drying.

[0059] S3. Mix the second component and the third component at a weight ratio of 1:(0.2~0.3), stir evenly, and mature for 20 minutes to 40 minutes to form a mixed coating for later use.

[0060] The second component comprises the following raw materials in parts by weight: 1 part epoxy resin or epoxy phenolic resin, 0.02 to 0.07 parts corrosion control component, 1.35 to 2.0 parts pigments and fillers, 0.02 to 0.03 parts defoamer, 0.01 to 0.02 parts dispersant and 0.01 to 0.02 parts leveling agent;

[0061] The third component is an epoxy curing agent;

[0062] S4 involves applying resin coating to the surface of the pipe body of S2 once or multiple times by brushing or spraying until a composite anti-corrosion coating with a thickness of 100-200 μm is formed after curing.

[0063] Furthermore, in step S2, the drying method is natural drying or low-temperature drying, wherein the temperature of low-temperature drying is 20-60℃;

[0064] After applying the mixed coating once or multiple times in step S4, it is preferable to use room temperature curing or low temperature heating curing, with the temperature of low temperature heating curing controlled below 60°C.

[0065] This invention further protects the application of the above-mentioned composite anti-corrosion coating, which is suitable for water corrosion environments containing CO2 or mixed corrosion environments of crude oil and water, wherein the partial pressure of CO2 should not exceed 0.1 MPa, the total pressure should not exceed 10 MPa, and the ambient temperature should not exceed 100°C.

[0066] The present invention will be further described below with reference to specific embodiments:

[0067] Example 1

[0068] This embodiment provides a method for applying a composite anti-corrosion coating to N80 carbon steel sleeves, including the following steps:

[0069] S1, Preparation of the second component:

[0070] Mix 1 part by weight of epoxy resin, 0.02 parts by weight of defoamer BYK-190, 0.01 parts by weight of dispersant BYK-163 and 0.01 parts by weight of leveling agent BYK-358N evenly. Add 1.35 parts by weight of pigments and fillers under stirring conditions, mix evenly and grind. Then add 0.05 parts by weight of corrosion control component and disperse evenly to obtain the second component for later use.

[0071] S2, clean and sandblast the surface of N80 carbon steel sleeve to remove rust, so that the rust removal grade reaches 2.5a and the surface anchor texture is controlled at 40um;

[0072] S3, spray Ce(NO3)3 metal salt solution onto the tube surface in one go to ensure that the film thickness reaches 10um after drying;

[0073] S4. Mix the second component obtained in step S1 with the epoxy curing agent at a weight ratio of 1:0.3, stir evenly to form a mixed coating, and cure for 20 minutes for later use.

[0074] The epoxy curing agent is composed of 1 part by weight of modified aromatic amine curing agent TH-430 and 0.8 parts by weight of phenolic curing agent KD-401.

[0075] S5 involves applying a mixed coating to the pipe surface in one coat by brushing or spraying. After the coating cures, a composite anti-corrosion coating with a thickness of 100µm is formed.

[0076] Example 2

[0077] This embodiment provides a method for applying a composite anti-corrosion coating to 20# carbon steel seamless pipe, including the following steps:

[0078] S1, Preparation of the second component:

[0079] Mix 1 part by weight of epoxy resin, 0.03 parts by weight of defoamer BYK-024, 0.01 parts by weight of dispersant BYK-163 and 0.02 parts by weight of leveling agent BYK-358N evenly. Add 1.5 parts by weight of pigments and fillers while stirring, mix evenly and grind. Then add 0.02 parts by weight of corrosion control component and disperse evenly to obtain the second component for later use.

[0080] S2, clean and shot blast the surface of 20# carbon steel seamless pipe to achieve a rust removal grade of 2.5a and control the surface anchor texture at 40um;

[0081] S3, spray Ce(NO3)3 metal salt solution onto the tube surface in one go to ensure that the film thickness reaches 20um after drying;

[0082] S4. Mix the second component obtained in step S1 with the epoxy curing agent at a weight ratio of 1:0.2, stir evenly to form a mixed coating, and let it cure for 40 minutes for later use.

[0083] The epoxy curing agent is composed of 1 part by weight of modified aromatic amine curing agent TH-431 and 0.8 parts by weight of phenolic curing agent KD-410A.

[0084] S5 involves applying a mixed coating to the pipe surface in one coat by brushing or spraying. After the coating cures, a composite anti-corrosion coating with a thickness of 200 μm is formed.

[0085] Example 3

[0086] This embodiment provides a method for applying a composite anti-corrosion coating to carbon steel plates, including the following steps:

[0087] S1, Preparation of the second component:

[0088] Mix 1 part by weight of epoxy resin, 0.02 parts by weight of defoamer MEM-0349, 0.01 parts by weight of dispersant E525 and 0.02 parts by weight of leveling agent BYK-358N evenly, stir, add 1.8 parts by weight of pigments and fillers, mix evenly and grind, then add 0.07 parts by weight of corrosion control component and disperse evenly to obtain the second component, which is set aside for later use.

[0089] S2, the carbon steel plate surface is cleaned and sandblasted to remove rust, so that the rust removal grade reaches 2.5a and the surface anchor texture is controlled at 40um;

[0090] S3, apply Gd(NO3)3 metal salt solution twice to the surface of carbon steel plate to ensure that the film thickness after drying reaches 10um.

[0091] S4. Mix the second component obtained in step S1 with the epoxy curing agent at a weight ratio of 1:0.25, stir evenly to form a mixed coating, and cure for 30 minutes for later use.

[0092] The epoxy curing agent is composed of 1.0 parts by weight of modified aromatic amine curing agent TH-452N and 1.0 parts by weight of phenolic curing agent KD-410A.

[0093] S5 involves applying a mixed coating to the pipe surface using multiple brushing or spraying methods, which, after curing, forms a composite anti-corrosion coating with a thickness of 100µm.

[0094] Example 4

[0095] This embodiment provides a method for applying a composite anti-corrosion coating to carbon steel bars, including the following steps:

[0096] S1, Preparation of the second component:

[0097] Mix 1 part by weight of epoxy resin, 0.03 parts by weight of defoamer BYK-024, 0.01 parts by weight of dispersant BYK-163 and 0.02 parts by weight of leveling agent BYK-358N evenly. After stirring, add 1.45 parts by weight of pigments and fillers, mix evenly and grind. Then add 0.05 parts by weight of corrosion control component and disperse evenly to obtain the second component for later use.

[0098] S2, the surface of the carbon steel bar is cleaned and sandblasted to remove rust, so that the rust removal grade reaches 2.5a and the surface anchor texture is controlled at 60um;

[0099] S3, apply Sm(NO3)3 salt solution twice to the surface of the tube to ensure that the film thickness reaches 20um after drying;

[0100] S4. Mix the second component obtained in step S1 with the epoxy curing agent at a weight ratio of 1:0.25, stir evenly to form a mixed coating, and cure for 40 minutes for later use.

[0101] The epoxy curing agent is composed of 1 part by weight of modified aromatic amine curing agent TH-420 and 0.8 parts by weight of phenolic curing agent KD-426.

[0102] S5 involves applying a mixed coating to the pipe surface using multiple brushing or spraying methods, which, after curing, forms a composite anti-corrosion coating with a thickness of 200µm.

[0103] The composite anti-corrosion coatings prepared in Examples 1-3 were applied to obtain three types of coating samples. A conventional two-component epoxy coating without the first component and without corrosion control components was applied (thickness 200 μm) to obtain Comparative Example 1.

[0104] The coatings obtained in Examples 1-3 were subjected to performance tests. The main test indicators were appearance, three mechanical properties (adhesion, bending resistance, and impact resistance), and six corrosion resistance properties (resistance to electrical sparks, salt water, acid and alkali salt immersion, and high temperature and high pressure resistance). The performance of the coatings compared with those of conventional two-component epoxy coatings and their application (200 μm thickness) in Example 1 is shown in Table 1.

[0105] Table 1 - Product Performance Testing As shown in Table 1, Comparative Example 1 has essentially the same appearance and mechanical properties as Examples 1-3. However, Comparative Example 1, lacking the first component layer and the epoxy resin coating with corrosion control components, exhibits inferior corrosion resistance in six indicators compared to Examples 1-3. This reflects that Examples 1-3 demonstrate superior long-term corrosion resistance to various media.

[0106] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A composite anti-corrosion coating, characterized in that, It includes a first component, a second component, and a third component in a weight ratio of (0.01~0.05):1:(0.2~0.3), wherein: The first component is a lanthanide metal nitrate solution, used to form a dense film on the surface of a steel substrate; The second component comprises the following raw materials in parts by weight: 1 part epoxy resin, 0.02-0.07 parts corrosion control component, 1.35-2.0 parts pigments and fillers, 0.02-0.03 parts defoamer, 0.01-0.02 parts dispersant, and 0.01-0.02 parts leveling agent; wherein the corrosion control component comprises 0.01-0.02 parts zinc powder and 0.01-0.05 parts sodium silicate powder; The third component is an epoxy curing agent; In a corrosive environment, the film formed by the first component, and the zinc powder and sodium silicate in the coating formed by the mixed coating prepared by mixing the second and third components, generate Ln through an ionization reaction. 3+ —Zn 2+ —SiO3 2- A precipitation-type protective film layer is used to compensate for physical micropore defects in the coating. The lanthanide nitrate solution contains lanthanide nitrates with the molecular formula Ln(NO3)3·nH2O, where n = 5~7 and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, or Tm.

2. The composite anti-corrosion coating as described in claim 1, characterized in that: The concentration of the lanthanide nitrate solution is 0.1% to 30%.

3. The composite anti-corrosion coating as described in claim 1, characterized in that: The zinc powder is in the form of flakes with a fineness of <30µm and a zinc content of >96%; the sodium silicate powder is in the form of spheres, needles, or fibers with a fineness of 0.01~20µm.

4. The composite anti-corrosion coating as described in claim 1, characterized in that: The pigments and fillers, by weight, comprise the following components: 0.6-0.75 parts barium sulfate, 0.2-0.35 parts talc, 0.25-0.3 parts wollastonite, 0.3-0.45 parts mica, and 0.003-0.005 parts fumed silica.

5. The composite anti-corrosion coating as described in claim 1, characterized in that: The epoxy curing agent comprises, by weight, 1 part modified aromatic amine curing agent and 0.8 to 1 part phenolic curing agent.

6. The composite anti-corrosion coating as described in claim 1, characterized in that: The second component is prepared by mixing 1 part by weight of epoxy resin, 0.02-0.03 parts by weight of defoamer, 0.01-0.02 parts by weight of dispersant and 0.01-0.02 parts by weight of leveling agent evenly, adding 1.35-2.0 parts by weight of pigments and fillers under stirring, mixing evenly and grinding, and then adding 0.02-0.07 parts by weight of corrosion control component and dispersing evenly to obtain the second component.

7. The composite anti-corrosion coating as described in claim 1, characterized in that: The epoxy resin is an epoxy phenolic resin.

8. A method for applying a composite anti-corrosion coating as described in any one of claims 1-7, characterized in that, Includes the following steps: S1, clean the surface of the steel substrate, sandblast or shot blast to remove rust, the rust removal grade reaches 2.5a, and the surface anchor texture is controlled at 40~60µm; S2, Lanthanide metal nitrate solution is sprayed repeatedly onto the surface of the treated steel substrate until the film thickness on the tube surface reaches 10~20µm after drying. S3, prepare a mixed coating, wherein the mixed coating is prepared by mixing the second component and the third component; S4. On the surface of S2, the mixed coating is applied once or multiple times by brushing or spraying until it cures to form a composite anti-corrosion coating with a thickness of 100~400µm.

9. The coating method for the composite anti-corrosion coating as described in claim 8, characterized in that, The second component comprises the following raw materials in parts by weight: 1 part epoxy resin, 0.02-0.07 parts corrosion control component, 1.35-2.0 parts pigments and fillers, 0.02-0.03 parts defoamer, 0.01-0.02 parts dispersant, and 0.01-0.02 parts leveling agent; the third component is an epoxy curing agent; The preparation method of the mixed coating is as follows: the second component and the third component are mixed at a weight ratio of 1:(0.2~0.3), stirred evenly, and matured for 20 minutes to 40 minutes to form a mixed coating.

10. The coating method for the composite anti-corrosion coating as described in claim 8, characterized in that: In step S2, the drying method is natural drying or low-temperature drying, and the temperature of the low-temperature drying is 20~60℃. After applying the mixed coating once or multiple times in step S4, use room temperature curing or low temperature heating curing. The temperature for low temperature heating curing is controlled below 60℃.

11. The application of the composite anti-corrosion coating according to any one of claims 4-7, characterized in that: This composite anti-corrosion coating is applicable to water-corrosion environments containing CO2 or mixed corrosion environments of crude oil and water.

Images