Intelligent protective coating for steel structure and preparation method thereof

Abstract

The present application belongs to the field of metal corrosion protection and hydrogen energy safety technology, and relates to an intelligent protective coating for steel structure and a preparation method thereof. The intelligent protective coating for steel structure comprises a polymer matrix, a two-dimensional material or a functionalized two-dimensional material, a hydrogen-induced color change component, a curing agent and a solvent. The coating is a single-layer composite structure, and the hydrogen-induced color change component coats the two-dimensional material or the functionalized two-dimensional material. The present application provides a novel intelligent protective coating with efficient hydrogen blocking, long-term corrosion prevention and hydrogen damage self-warning functions. The labyrinth effect of the two-dimensional material can inhibit the diffusion of corrosion medium, and the coated PANI can induce the generation of a passivation film on the metal surface and has hydrogen-induced color change characteristics. The oxidation state PANI reacts with atomic hydrogen permeating into the coating to reduce the quinone structure to the benzene structure, and the color gradually changes from dark green to yellow green, realizing in-situ and visual monitoring of hydrogen permeation behavior.

Description

Technical Field

[0001] This invention belongs to the field of metal corrosion protection and hydrogen energy safety technology, and relates to an intelligent protective coating for steel structures and its preparation method. Specifically, it relates to a self-early warning hydrogen-blocking and corrosion-resistant intelligent protective coating for hydrogen-blended natural gas pipelines, hydrogen storage containers and hydrogen-related steel structures and its preparation method. Background Technology

[0002] Hydrogen energy, as a clean energy carrier, requires large-scale storage and transportation as a crucial link in achieving energy structure transformation. Pipeline transportation is the most economical method for large-scale, long-distance hydrogen storage and transportation, and its safety directly restricts the healthy development of the hydrogen energy industry chain. In the scenario of hydrogen-blended natural gas transportation, pipeline steel faces a dual threat of damage: on the one hand, hydrogen molecules adsorb and dissociate into hydrogen atoms on the metal surface and diffuse inward, causing hydrogen embrittlement in high-strength pipeline steel; on the other hand, corrosive media such as H2O, CO2, and H2S associated with natural gas can trigger electrochemical corrosion. The resulting microscopic corrosion defects not only become rapid channels for hydrogen diffusion, but the additional hydrogen atoms generated by the cathodic reduction reaction will further exacerbate hydrogen permeation. The "synergistic intrusion" of gaseous hydrogen and cathodic reduced hydrogen not only exacerbates the risk of hydrogen damage to pipeline steel but also alters its corrosion destruction mechanism, making pipeline protection in hydrogen-blended transportation environments far more difficult than that of conventional oil and gas pipelines.

[0003] In existing technologies, ceramic hydrogen barrier coatings (such as Al2O3, Cr2O3, TiN, TiC, etc.) exhibit excellent hydrogen barrier performance in environments such as nuclear engineering, but they are inherently brittle, have weak adhesion to steel substrates, and are complex and costly to prepare. Polymer coatings (such as epoxy resins) show great application potential due to their excellent film-forming properties, good adhesion, and convenient application process, but their inherent free volume and amorphous defects limit further improvement in barrier performance.

[0004] Therefore, developing a novel intelligent protective coating that combines high-efficiency hydrogen barrier, long-lasting corrosion protection, and self-warning function against hydrogen damage is of significant engineering value and scientific importance. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent protective coating for steel structures and its preparation method, which solves the technical problems of existing coatings having poor hydrogen barrier performance, easy failure, and inability to monitor hydrogen permeation behavior in real time in hydrogen-containing natural gas environments.

[0006] A smart protective coating for steel structures comprises the following components: a polymer matrix, a two-dimensional material or a functionalized two-dimensional material, a hydrochromic component, a curing agent, and a solvent; the coating is a single-layer composite structure, wherein the hydrochromic component encapsulates the two-dimensional material or the functionalized two-dimensional material.

[0007] Furthermore, the polymer matrix is ​​one or more combinations of epoxy resin, fluorocarbon resin, polyurethane, polyolefin, or ethylene-vinyl alcohol copolymer.

[0008] Furthermore, the two-dimensional material is one or more combinations of graphene (Gr), graphene oxide (GO), boron nitride (BN), carbon nitride (C3N4), glass flakes (GFs), and metal-organic frameworks (MOFs).

[0009] Preferably, the two-dimensional material undergoes surface functionalization modification to introduce one or more combinations of active functional groups such as hydroxyl (-OH), amino (-NH2), carboxyl (-COOH), or epoxy (-CH(O)CH-).

[0010] Furthermore, the hydrogen-induced color-changing component is polyaniline (PANI).

[0011] Furthermore, the curing agent is one or more combinations of amines, acid anhydrides, and isocyanates.

[0012] Furthermore, the solvent is any one or a combination of two or more of xylene, n-butanol, ethanol or water.

[0013] Furthermore, additives may be added, which may be one or more combinations of dispersants, wetting agents, defoamers, leveling agents, thickeners, and film-forming aids.

[0014] A method for preparing a smart protective coating for steel structures includes the following steps: Step 1: Preparation of functionalized two-dimensional materials: Take 1-10 parts by mass of two-dimensional material and ultrasonically disperse it in 50-1000 parts of solvent. Then add 1-100 parts of modifier to react. After the reaction is completed, centrifuge, wash and dry to obtain functionalized two-dimensional materials with surface grafted active functional groups. Step 2: Preparation of PANI-coated two-dimensional material hybrid filler: Take 0.1-1 parts by weight of the two-dimensional material (or 0.1-1 parts by weight of the functionalized two-dimensional material obtained in Step 1) and 0.1-10 parts by weight of the aniline monomer, and ultrasonically disperse them in 10-500 parts by weight of an acidic aqueous solution to obtain a two-dimensional material dispersion. Then, take 0.1-50 parts by weight of ammonium persulfate and ultrasonically disperse them in 10-200 parts by weight of an acidic aqueous solution. Under stirring conditions, add the acidic aqueous solution of ammonium persulfate dropwise to the above two-dimensional material dispersion and react. After the reaction is complete, centrifuge and wash the obtained precipitate until neutral, and vacuum dry it to obtain the PANI-coated two-dimensional material hybrid filler. Step 3, Coating preparation: By mass, take 1-20 parts of the PANI-coated two-dimensional material hybrid filler obtained in Step 2 and add it to 10-100 parts of solvent and 10-100 parts of polymer matrix. Stir evenly to obtain coating mother liquor. Add curing agent to the above coating mother liquor and mix evenly. Apply the mixture to the surface-treated metal substrate and cure to obtain intelligent protective coating.

[0015] Furthermore, in step 1, the solvent is any one or a combination of two or more of methanol, ethanol, or water.

[0016] Further, in step 1, the modifier is one or more combinations of silane coupling agents, dopamine, tripolyphosphate, sodium hydroxide, or oligomers.

[0017] Furthermore, in step 1, the reaction temperature is 0~200℃ and the reaction time is 2~48 hours.

[0018] Further, in step 2, the acidic aqueous solution is an aqueous solution of hydrochloric acid, sulfuric acid, or sulfosalicylic acid; the concentration of the acidic aqueous solution is 0.1~1 mol / L; and the pH of the acidic aqueous solution is 1~5.

[0019] Furthermore, in step 2, the reaction temperature is 0~30 ℃ and the reaction time is 2~24 hours.

[0020] Furthermore, in step 2, the thickness of the PANI coating layer is 10~1000 nm.

[0021] Furthermore, in step 3, the solvent is any one or a combination of two or more of xylene, n-butanol, ethanol, or water.

[0022] Furthermore, in step 3, the mass ratio of the curing agent to the mother liquor is 1:1~5.

[0023] Furthermore, in step 3, additives may be added, which may be one or more combinations of dispersants, wetting agents, defoamers, leveling agents, thickeners, and film-forming aids.

[0024] Furthermore, in step 3, the coating method is one or more combinations of dip coating, spray coating, brush coating, roller coating, and spin coating.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0026] 1. This invention provides an intelligent protective coating for steel structures, achieving long-term blocking of hydrogen permeation pathways in complex environments. Through the covalent cross-linking of two-dimensional material surface active functional groups with polymer matrix and the condensation reaction between them and hydroxyl groups on the surface of metal matrix, chemical bonding is achieved at the dual interfaces of "filler-resin" and "coating-matrix", improving coating adhesion by 20-80% compared to traditional physical adhesion.

[0027] 2. This invention provides a novel intelligent protective coating that combines high-efficiency hydrogen barrier, long-lasting corrosion protection, and self-warning function against hydrogen damage. The labyrinth effect of two-dimensional materials inhibits the diffusion of corrosive media. The coated PANI can induce the formation of a passivation film on the metal surface and also exhibits hydrogen-induced color-changing properties—oxidized PANI (emerald green imine salt, dark green) undergoes a hydrogenation reaction with atomic hydrogen penetrating the coating, reducing the quinone structure to a benzene structure (reduced state, yellow-green), and the color gradually changes from dark green to yellow-green, achieving in-situ, visual monitoring of hydrogen permeation behavior.

[0028] 3. The intelligent protective coating provided by this invention is applicable to complex environments such as oil and gas pipelines. The coating's color changes reflect the internal hydrogen permeation path and corrosion location, making it more convenient and intuitive compared to existing technologies. Attached Figure Description

[0029] Figure 1 The image shows a surface SEM image of the PANI / GO hybrid filler in Example 1.

[0030] Figure 2 The image shows a surface SEM image of the PANI / Gr hybrid filler in Example 2.

[0031] Figure 3 for Figure 2 EDS surface scan of nitrogen corresponding to the SEM image.

[0032] Figure 4 This is a surface morphology diagram of the hydrogen-blocking and corrosion-resistant intelligent protective coating with self-early warning function in Example 3. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments, but is not limited to these embodiments.

[0034] A smart protective coating for steel structures comprises the following components: a polymer matrix, a two-dimensional material or a functionalized two-dimensional material, a hydrochromic component, a curing agent, and a solvent; the coating is a single-layer composite structure, wherein the hydrochromic component encapsulates the two-dimensional material or the functionalized two-dimensional material.

[0035] In one possible embodiment, the polymer matrix is ​​one or more combinations of epoxy resin, fluorocarbon resin, polyurethane, polyolefin, or ethylene-vinyl alcohol copolymer.

[0036] In one possible embodiment, the two-dimensional material is one or more combinations of graphene (Gr), graphene oxide (GO), boron nitride (BN), carbon nitride (C3N4), glass flakes (GFs), and metal-organic frameworks (MOFs).

[0037] Preferably, the two-dimensional material undergoes surface functionalization modification to introduce one or more combinations of active functional groups such as hydroxyl (-OH), amino (-NH2), carboxyl (-COOH), or epoxy (-CH(O)CH-).

[0038] In one possible embodiment, the hydrogen-chromic component is polyaniline (PANI).

[0039] In one possible embodiment, the curing agent is one or more combinations of amines, acid anhydrides, and isocyanates.

[0040] In one possible embodiment, the solvent is any one or a combination of two or more of xylene, n-butanol, ethanol, or water.

[0041] In one possible embodiment, an auxiliary agent may also be added, which is one or more combinations of dispersants, wetting agents, defoamers, leveling agents, thickeners, and film-forming agents.

[0042] A method for preparing a smart protective coating for steel structures includes the following steps: Step 1: Preparation of functionalized two-dimensional materials: Take 1-10 parts by mass of two-dimensional material and ultrasonically disperse it in 50-1000 parts of solvent. Then add 1-100 parts of modifier to react. The reaction temperature is 0-200℃ and the reaction time is 2-48 hours. After the reaction is completed, centrifuge, wash and dry to obtain functionalized two-dimensional materials with surface grafted active functional groups. Step 2: Preparation of PANI-coated two-dimensional material hybrid filler: Take 0.1-1 parts by weight of the two-dimensional material (or 0.1-1 parts by weight of the functionalized two-dimensional material obtained in Step 1) and 0.1-10 parts by weight of the aniline monomer, and ultrasonically disperse them in 10-500 parts by weight of an acidic aqueous solution to obtain a two-dimensional material dispersion. Then, take 0.1-50 parts by weight of ammonium persulfate, and ultrasonically disperse them in 10-200 parts by weight of an acidic aqueous solution. Under stirring conditions, add the acidic aqueous solution of ammonium persulfate dropwise to the above two-dimensional material dispersion and react. The reaction temperature is 0-30 °C, and the reaction time is 2-24 hours. After the reaction is completed, centrifuge and wash the obtained precipitate until neutral, and vacuum dry it to obtain the PANI-coated two-dimensional material hybrid filler. Step 3, Coating Preparation: By mass, take 1-20 parts of the PANI-coated two-dimensional material hybrid filler obtained in Step 2 and add it to 10-100 parts of solvent and 10-100 parts of polymer matrix. Stir evenly to obtain coating mother liquor. Add curing agent to the above coating mother liquor and mix evenly. The mass ratio of curing agent to mother liquor is 1:1-5. Coat the surface-treated metal substrate and cure to obtain intelligent protective coating.

[0043] In one possible embodiment, in step 1, the solvent is any one or a combination of two or more of methanol, ethanol, or water.

[0044] In one possible embodiment, in step 1, the modifier is one or more combinations of silane coupling agents, dopamine, tripolyphosphate, sodium hydroxide, or oligomers.

[0045] In one possible embodiment, in step 2, the acidic aqueous solution is an aqueous solution of hydrochloric acid, sulfuric acid, or sulfosalicylic acid; the concentration of the acidic aqueous solution is 0.1~1 mol / L; and the pH of the acidic aqueous solution is 1~5.

[0046] In one possible embodiment, in step 2, the thickness of the PANI coating layer is 10~1000 nm.

[0047] In one possible embodiment, in step 3, the solvent is any one or a combination of two or more of xylene, n-butanol, ethanol, or water.

[0048] In one possible embodiment, in step 3, an auxiliary agent may also be added, which may be one or more combinations of dispersants, wetting agents, defoamers, leveling agents, thickeners, and film-forming agents.

[0049] In one possible embodiment, in step 3, the coating method is one or more combinations of dip coating, spray coating, brush coating, roller coating, and spin coating.

[0050] Example 1.

[0051] A method for preparing a smart protective coating for steel structures includes the following steps: Step 1: Dissolve 5.7 g of ammonium persulfate in 100 mL of 0.1 mol / L hydrochloric acid solution and sonicate for 1 h to obtain solution A; add 1.0 g of graphene oxide and 1.9 g of aniline to 300 mL of 0.1 mol / L hydrochloric acid solution and sonicate for 2 h to obtain solution B; Step 2: Under the stirring condition of 1000 r / min in an ice-water bath, solution A was slowly added dropwise to solution B, and the reaction was stirred in an ice-water bath for 6 h; after the reaction was completed, the obtained precipitate was centrifuged and washed until neutral, and then vacuum dried to obtain polyaniline-coated graphene oxide (PANI / GO) hybrid filler. Figure 1 ); Step 3: Take 1.0 g of PANI / GO hybrid filler from step (2) and add it to a mixture of 20.0 g of deionized water and 100.0 g of waterborne epoxy resin (EPIKOTE 3520-WY-55A). Stir and disperse for 2 h to obtain the coating mother liquor. Take 50 g of waterborne curing agent (EPIKURE8537-MY-60) and add it to the mother liquor. Mix it evenly and apply it to the surface-treated metal substrate by spraying. After curing, the intelligent protective coating is obtained.

[0052] Figure 1 In the process, the GO surface is uniformly coated with PANI particles, and the originally smooth surface becomes rough, indicating that the PANI / GO hybrid filler was successfully prepared.

[0053] Example 2.

[0054] A method for preparing a smart protective coating for steel structures includes the following steps: Step 1: Dissolve 1.9 g of ammonium persulfate in 100 mL of 0.1 mol / L sulfuric acid solution, and disperse by ultrasonication for 0.5 h to obtain solution A; at the same time, add 0.1 g of graphene and 0.8 g of aniline to 200 mL of 0.1 mol / L sulfuric acid solution, and disperse by ultrasonication for 1 h to obtain solution B; Step 2: Under the stirring condition of 1000 r / min in an ice-water bath, solution A was slowly added dropwise to solution B, and the reaction was stirred in an ice-water bath for 6 h; after the reaction was completed, the obtained precipitate was centrifuged and washed until neutral, and then vacuum dried to obtain polyaniline-coated graphene (PANI / Gr) hybrid filler. Figure 2 ); Step 3: Measure 7.0 g xylene and 3.0 g n-butanol, mix them, and dissolve them in 35 g epoxy resin E44. Take 1.5 g PANI / Gr hybrid filler and add it together with the dissolved E44 into 300 mL agate mortar. After ball milling and dispersion for 2 h, a coating mother liquor is obtained. Take 15 g polyamide curing agent-651 and add it to the mother liquor and mix it evenly. Apply it to the surface-treated metal substrate by spraying. After curing, a hydrogen-blocking and anti-corrosion smart coating with self-warning function is obtained.

[0055] Figure 2 The surface of the medium Gr is completely covered by PANI, and the originally smooth lamellar surface becomes rough, as shown in the corresponding EDS surface scan ( Figure 3 The results show that nitrogen is distributed relatively evenly on the Gr surface, indicating that the PANI / Gr hybrid filler was successfully prepared and can be uniformly coated on the Gr surface.

[0056] Example 3.

[0057] A method for preparing a smart protective coating for steel structures includes the following steps: Step 1: Disperse 1.0 g of boron nitride ultrasonically in a mixture of 10 mL of deionized water and 90 mL of ethanol. Simultaneously, dissolve 20 g of silane coupling agent (KH-550) in 50 mL of ethanol. Then, pour the fully dissolved silane coupling agent and boron nitride dispersion into a three-necked flask and react in a water bath at 60 °C for 8 h with a stirring speed of 500 r / min. After the reaction is complete, centrifuge, wash, and dry the precipitate to obtain functionalized boron nitride. Step 2: Dissolve 3.2 g of ammonium persulfate in 50 mL of 1 mol / L hydrochloric acid solution, and sonicate for 0.5 h to obtain solution A; at the same time, add 0.2 g of functionalized boron nitride and 1.2 g of aniline to 100 mL of 1 mol / L hydrochloric acid solution, and sonicate for 2 h to obtain solution B; Step 3: Under the stirring condition of 1000 r / min ice-water bath, solution A is slowly added dropwise to solution B, and the reaction is stirred in the ice-water bath for 8 h. After the reaction is completed, the obtained precipitate is centrifuged and washed until neutral, and then vacuum dried to obtain polyaniline-coated boron nitride (PANI / BN) hybrid filler.

[0058] Step 4: Measure 7.0 g xylene and 3.0 g n-butanol, mix them, and dissolve them in 35 g epoxy resin E44; take 2.5 g PANI / BN hybrid filler, add it together with the dissolved E44 to 300 mL agate mortar, ball mill and disperse for 2 h to obtain coating mother liquor, take 15 g polyamide curing agent-651 and add it to the mother liquor and mix evenly, then apply it to the surface-treated metal substrate by spraying. After curing, a hydrogen-barrier and anti-corrosion intelligent coating with self-warning function is obtained. Figure 4 ).

[0059] Figure 4 In the study, the epoxy coating modified with PANI / BN hybrid filler was dark green, and the filler was evenly dispersed in the coating without obvious agglomeration.

[0060] To test the performance of the intelligent protective coating for steel structures of the present invention, comparative examples were designed in the sample preparation: Comparative Example 1 was a pure water-based epoxy resin coating without PANI / GO hybrid filler as in Example 1; Comparative Example 2 was a pure epoxy resin coating without PANI / Gr hybrid filler as in Example 2; and Comparative Example 3 was an epoxy resin coating with the same mass fraction of unmodified boron nitride as in Example 3. The coating performance results are shown in Table 1 after neutral salt spray testing (after 480 h), coating adhesion testing, electrochemical impedance spectroscopy testing (after immersion in 3.5 wt.% NaCl aqueous solution for 600 h), and electrochemical hydrogen permeation testing.

[0061] Table 1. Results of coating performance test.

[0062] As shown in Table 1, the overall performance of the coating product prepared by this invention is superior to that of the comparative example. Specifically, the corrosion resistance and hydrogen barrier properties of the embodiment are significantly better than those of the comparative example, indicating that the layered structure of the two-dimensional material can form a "maze effect" in the resin matrix, effectively improving the barrier and protective performance of the coating. Simultaneously, the redox nature of polyaniline can induce passivation of the matrix metal and consume some hydrogen atoms through hydrogenation. Furthermore, the active functional groups grafted onto the surface of the hybrid filler improve its compatibility with the polymer matrix, allowing the filler to be more uniformly dispersed in the resin and to hybridize and bond with hydroxyl groups on the metal surface, solving the problem of a weak coating-metal interface and thus improving the adhesion of the coating system.

Claims

1. A smart protective coating for steel structures, characterized in that, It comprises the following components: polymer matrix, two-dimensional material or functionalized two-dimensional material, hydrochromic component, curing agent, and solvent; the coating is a single-layer composite structure, with the hydrochromic component coating the two-dimensional material or functionalized two-dimensional material.

2. The intelligent protective coating for steel structures according to claim 1, characterized in that, The polymer matrix is ​​one or more combinations of epoxy resin, fluorocarbon resin, polyurethane, polyolefin, or ethylene-vinyl alcohol copolymer.

3. The intelligent protective coating for steel structures according to claim 1, characterized in that, The two-dimensional material is one or more combinations of graphene, graphene oxide, boron nitride, carbon nitride, glass flakes, and metal-organic frameworks.

4. The intelligent protective coating for steel structures according to claim 1, characterized in that, Two-dimensional materials are surface functionalized by introducing one or more combinations of active functional groups, such as hydroxyl, amino, carboxyl, or epoxy groups.

5. The intelligent protective coating for steel structures according to claim 1, characterized in that, The hydrogen-induced color-changing component is polyaniline.

6. A method for preparing an intelligent protective coating for steel structures, characterized in that, Includes the following steps: Step 1: Preparation of functionalized two-dimensional materials: Take 1-10 parts by mass of two-dimensional material and ultrasonically disperse it in 50-1000 parts of solvent. Then add 1-100 parts of modifier to react. After the reaction is completed, centrifuge, wash and dry to obtain functionalized two-dimensional materials with surface grafted active functional groups. Step 2: Preparation of PANI-coated two-dimensional material hybrid filler: Take 0.1-1 parts by weight of two-dimensional material or 0.1-1 parts by weight of functionalized two-dimensional material and 0.1-10 parts by weight of aniline monomer, and ultrasonically disperse them in 10-500 parts by weight of acidic aqueous solution to obtain a two-dimensional material dispersion. Then, take 0.1-50 parts by weight of ammonium persulfate and ultrasonically disperse them in 10-200 parts by weight of acidic aqueous solution. Under stirring conditions, add the acidic aqueous solution of ammonium persulfate dropwise to the above two-dimensional material dispersion and react. After the reaction is complete, centrifuge and wash the obtained precipitate until neutral, and vacuum dry it to obtain PANI-coated two-dimensional material hybrid filler. Step 3, Coating preparation: By mass, take 1-20 parts of the PANI-coated two-dimensional material hybrid filler obtained in Step 2 and add it to 10-100 parts of solvent and 10-100 parts of polymer matrix. Stir evenly to obtain coating mother liquor. Add curing agent to the above coating mother liquor and mix evenly. Apply the mixture to the surface-treated metal substrate and cure to obtain intelligent protective coating.

7. The method for preparing the intelligent protective coating for steel structures according to claim 6, characterized in that, In step 1, the modifier is one or more combinations of silane coupling agent, dopamine, tripolyphosphate, sodium hydroxide, or oligomer.

8. The method for preparing the intelligent protective coating for steel structures according to claim 6, characterized in that, In step 1, the reaction temperature is 0~200℃ and the reaction time is 2~48 hours.

9. The method for preparing the intelligent protective coating for steel structures according to claim 6, characterized in that, In step 2, the reaction temperature is 0~30 ℃ and the reaction time is 2~24 hours.

10. The method for preparing the intelligent protective coating for steel structures according to claim 6, characterized in that, In step 3, the mass ratio of curing agent to mother liquor is 1:1~5.

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