A corrosion-resistant galvanized steel pipe and its preparation process

Abstract

The present invention relates to the technical field of galvanized steel pipes, and discloses a corrosion-resistant galvanized steel pipe and a preparation process thereof; in the present invention, an amino-modified carbon dot inhibitor is synthesized by a hydrothermal method, and then dopamine monomers are covalently bonded to its surface through a coupling reaction to prepare a functionalized carbon dot inhibitor. Finally, it is used as an intercalating agent to modify and exfoliate boron nitride to prepare intercalation-modified boron nitride nanosheets; dopamine is used to modify nano-zinc oxide particles, and the Π-Π stacking effect between the catechol groups on polydopamine and the aromatic rings on the inhibitor is utilized, and then a large number of active functional groups on polydopamine are used to graft KH590 on its surface to prepare modified zinc oxide nanoparticles. Finally, it is loaded on the intercalation-modified boron nitride nanosheets through a dehydration condensation reaction to prepare composite boron nitride nanosheets. It is used as the main component of the passivator to form a passivation film on the galvanized steel pipe, and finally a corrosion-resistant galvanized steel pipe is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of galvanized steel pipes, and specifically to a corrosion-resistant galvanized steel pipe and its preparation process. Background Technique

[0002] Hot-dip galvanizing technology is often used to prevent the steel substrate from being affected by corrosion. However, in the atmosphere, white rust is likely to accumulate on the surface of the hot-dip galvanized layer, which has an adverse effect on the appearance and quality of hot-dip galvanized products. To solve this problem, passivation treatment of the hot-dip galvanized surface is usually adopted to effectively protect the hot-dip galvanized layer from corrosion; through this comprehensive protection measure, hot-dip galvanized products can not only form a strong protective layer on the surface, effectively resist external corrosion factors, but also maintain their appearance and quality, ensuring that they can maintain excellent performance under various environmental conditions. These measures are crucial for improving the reliability and durability of hot-dip galvanized products.

[0003] Therefore, it is of great significance to invent a corrosion-resistant galvanized steel pipe and its preparation process. Summary of the Invention

[0004] The purpose of the present invention is to provide a corrosion-resistant galvanized steel pipe and its preparation process to solve the problems raised in the above background technique.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A preparation process of a corrosion-resistant galvanized steel pipe includes the following steps:

[0007] S1: Add glucose, anhydrous citric acid, 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole into deionized water, heat to 180 - 185 °C and react for 4 - 4.5 h, cool, carry out reduced-pressure filtration, purification, and freeze-drying to obtain a carbon dot corrosion inhibitor;

[0008] S2: Ultrasonically disperse the carbon dot corrosion inhibitor in deionized water, adjust the pH to 6 - 6.5; add 1-ethyl-carbodiimide hydrochloride solution and N-hydroxysuccinimide solution, activate, add dopamine, remove dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 - 3.5 h, purify, and vacuum-dry to obtain a modified carbon dot corrosion inhibitor;

[0009] S3: Ultrasonically disperse the modified carbon dot corrosion inhibitor and hexagonal boron nitride in an aqueous solution of N,N-dimethylformamide, centrifuge, carry out reduced-pressure filtration on the supernatant, purify, and vacuum-dry to obtain an intercalated modified boron nitride nanosheet;

[0010] S4: Ultrasonically disperse zinc oxide nanoparticles in Tris-HCl solution, add dopamine and inhibitor solution, react at room temperature for 24 - 26 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse modified zinc oxide nanoparticles A in N,N-dimethylformamide, add KH590, heat to 80 - 85 °C and react for 3 - 4 h to obtain modified zinc oxide nanoparticles B;

[0011] S5: Ultrasonically disperse intercalated modified boron nitride nanosheets in N,N-dimethylformamide, add modified zinc oxide nanoparticles B and disperse evenly, heat to 105 - 107 °C and react for 5 - 6 h, purify, and vacuum dry to obtain composite boron nitride nanosheets;

[0012] S6: Dissolve tannic acid in deionized water, add fatty alcohol polyoxyethylene ether, hydroxyethylidene diphosphonic acid, and emulsifier and stir evenly, add aqueous acrylic resin solution and stir evenly, add composite boron nitride nanosheets and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 - 32 °C, immerse the galvanized steel pipe in the passivation solution for 20 - 30 s, take out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0013] Further, in the carbon dot inhibitor, the mass ratio of glucose:anhydrous citric acid:4-amino-3-hydrazino-5-mercapto-1,2,4-triazole is 1:1:(0.5 - 1.2);

[0014] Further, in the modified carbon dot inhibitor, the mass ratio of carbon dot inhibitor:dopamine is 80:(60 - 75.9); the concentration of 1-ethyl-carbodiimide hydrochloride solution is 0.1 mol / L; the concentration of N-hydroxysuccinimide solution is 0.1 mol / L;

[0015] Further, in the intercalated modified boron nitride nanosheets, the mass ratio of modified carbon dot inhibitor:hexagonal boron nitride is (0.25 - 0.5):0.2;

[0016] Further, in the modified zinc oxide nanoparticles A, the mass ratio of zinc oxide nanoparticles:dopamine:inhibitor in the inhibitor solution is 2:(2 - 3):(8 - 9); the concentration of Tris-HCl solution is 10 mM, pH is 8.5; the concentration of the inhibitor solution is 160 mg / mL, and the inhibitor is any one of benzimidazole and benzotriazole;

[0017] Further, in the modified zinc oxide nanoparticles B, the mass ratio of modified zinc oxide nanoparticles A:KH590 is (4 - 5):(1.6 - 3);

[0018] Further, in the composite boron nitride nanosheets, the mass ratio of the intercalation-modified boron nitride nanosheets to the modified zinc oxide nanoparticles B is 3:(1-2);

[0019] Further, in terms of mass parts, the proportion of each component in the passivation solution is as follows: 0.5-0.8 parts of tannic acid, 0.15-0.2 parts of fatty alcohol polyoxyethylene ether, 0.15-0.2 parts of hydroxyethylidene diphosphonic acid, 0.15-0.2 parts of emulsifier, 40-50 parts of aqueous acrylic resin solution, and 1-5 parts of composite boron nitride nanosheets.

[0020] Further, the emulsifier is OP-10.

[0021] Further, the preparation method of the galvanized steel pipe includes the following steps:

[0022] The steel pipe substrate is sequentially subjected to degreasing, water washing, pickling, and water washing pretreatment; the pretreated steel pipe is placed in a chemical plating solution and heated to 50-55 °C for constant-temperature chemical zinc plating for 10-15 min to obtain a galvanized steel pipe;

[0023] Further, the solution used in the degreasing step is a 10 wt% sodium hydroxide solution, and the solution used in the pickling step is a 16 wt% hydrochloric acid solution; the thickness of the zinc coating of the galvanized steel pipe is 8-9 μm.

[0024] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0025] In the present invention, an amino-modified carbon dot corrosion inhibitor is synthesized by a hydrothermal method, and then dopamine monomers are covalently bonded to its surface by an EDC / NHS coupling reaction to prepare a functionalized carbon dot corrosion inhibitor. Finally, it is used as an intercalating agent to modify and exfoliate boron nitride to prepare intercalation-modified boron nitride nanosheets. The doping of the nano-composite filler significantly improves the long-term corrosion resistance of the passivation solution. The dual role of the functionalized carbon dot corrosion inhibitor as an intercalating agent: on the one hand, it increases the interlayer distance of the boron nitride sheets, significantly improves the dispersibility of the boron nitride nanosheets, and the exfoliated boron nitride nanosheets play a maze effect, effectively extending the diffusion path of the corrosive medium and plugging the inherent defects inside the coating; on the other hand, the dopamine catechol residues on the surface of the intercalating agent can specifically interact with Fe 3+ or Fe 2+ to form a stable complex, blocking the contact between the steel surface and the corrosive medium, and greatly improving the corrosion resistance of the passivation layer.

[0026] The present invention uses zinc oxide nanoparticles as a template, modifies them by coating a layer of polydopamine on their surface, and utilizes the π-π stacking effect between the catechol groups on the polydopamine and the aromatic rings on the corrosion inhibitor to load the polydopamine as an anchor point for the corrosion inhibitor on it. Then, by using a large number of active functional groups on the polydopamine, KH590 is grafted onto the surface of the polydopamine-modified zinc oxide nanoparticles loaded with the corrosion inhibitor through Michael addition reaction to prepare modified zinc oxide nanoparticles. Finally, it is loaded onto the intercalation-modified boron nitride nanosheets through the dehydration condensation reaction of a silane coupling agent to prepare composite boron nitride nanosheets; by using the chelating property of polydopamine with Zn 2+ the shielding effect of the metal chelate on the surface of the galvanized steel pipe is further improved, and the corrosion resistance of the passivation layer is further enhanced.

[0027] The functionalized carbon dot corrosion inhibitor and the modified zinc oxide nanoparticles are successively loaded into the boron nitride nanosheets through intercalation and condensation, greatly expanding the corrosion-resistant application range of the passivation solution. On the one hand, when the pH of the corrosive medium is slightly neutral, the functionalized carbon dot corrosion inhibitor as an intercalating agent can interact specifically with Fe 3+ or Fe 2+ to form a stable complex; on the other hand, the prepared modified zinc oxide nanoparticles achieve a slow-release effect by using the pH-responsive behavior of polydopamine. When the pH is biased towards acidity, due to the positive charge repulsion between polydopamine and the amino group on the corrosion inhibitor, a large amount of the corrosion inhibitor is released, providing corrosion inhibition performance for the galvanized steel pipe; the combination of the two greatly broadens the application range of the galvanized steel pipe and provides excellent corrosion protection for the steel pipe. Specific embodiments

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] In the following embodiments, the particle size of hexagonal boron nitride is 5 - 10 μm, purchased from Beijing Pusitang Biotechnology Co., Ltd.; the crystal form of zinc oxide nanoparticles is α-type, and the particle size is 20 nm, purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; the model of the steel pipe substrate is Q235, purchased from Wuxi Chuanyue Iron and Steel Co., Ltd.; the rest of the raw materials are commercially available.

[0030] The preparation method of the galvanized steel pipe includes the following steps:

[0031] The steel pipe substrate is successively degreased with 10 wt% sodium hydroxide solution, washed with deionized water, pickled with 16 wt% hydrochloric acid solution, and washed with deionized water for pretreatment; the pretreated steel pipe is placed in a chemical plating solution, heated to 50 °C, and subjected to constant-temperature chemical zinc plating for 10 min to obtain a galvanized steel pipe with a zinc coating thickness of 8 μm.

[0032] Example 1: A preparation process of a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole to deionized water, heat to 180 °C and react for 4 h, cool, perform vacuum filtration under reduced pressure, purify, and freeze-dry to obtain a carbon dot corrosion inhibitor;

[0033] S2: Ultrasonically disperse 80 mg of the carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of 0.1 mol / L N-hydroxysuccinimide solution, activate, add 60 mg of dopamine, remove the dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum-dry to obtain a modified carbon dot corrosion inhibitor;

[0034] S3: Ultrasonically disperse 2.5 g of the modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an N,N-dimethylformamide aqueous solution, centrifuge, and subject the supernatant to vacuum filtration, purification, and vacuum drying to obtain an intercalated modified boron nitride nanosheet;

[0035] S4: Ultrasonically disperse 2 g of zinc oxide nanoparticles in 10 mM Tris-HCl solution, add 2 g of dopamine and 8 g of benzotriazole, react at room temperature for 24 h, purify, and vacuum-dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 1.6 g of KH590, and heat to 80 °C and react for 3 h to obtain modified zinc oxide nanoparticles B;

[0036] S5: Ultrasonically disperse 3 g of the intercalated modified boron nitride nanosheet in N,N-dimethylformamide, add 1 g of modified zinc oxide nanoparticles B and disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum-dry to obtain a composite boron nitride nanosheet;

[0037] S6: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10 and stir evenly, add 40 g of an aqueous acrylic resin solution and stir evenly, add 1 g of the composite boron nitride nanosheet and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take it out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0038] Example 2: Preparation process of a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole into deionized water, heat to 180 °C and react for 4 h, cool, perform vacuum filtration under reduced pressure, purify, and freeze-dry to obtain a carbon dot corrosion inhibitor;

[0039] S2: Ultrasonically disperse 80 mg of the carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of 0.1 mol / L N-hydroxysuccinimide solution, activate, add 75.9 mg of dopamine, remove the dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum dry to obtain a modified carbon dot corrosion inhibitor;

[0040] S3: Ultrasonically disperse 2.5 g of the modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an N,N-dimethylformamide aqueous solution, centrifuge, perform vacuum filtration on the supernatant, purify, and vacuum dry to obtain an intercalated modified boron nitride nanosheet;

[0041] S4: Ultrasonically disperse 2 g of zinc oxide nanoparticles in 10 mM Tris-HCl solution, add 2 g of dopamine and 8 g of benzotriazole, react at room temperature for 24 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 1.6 g of KH590, and heat to 80 °C and react for 3 h to obtain modified zinc oxide nanoparticles B;

[0042] S5: Ultrasonically disperse 3 g of the intercalated modified boron nitride nanosheet in N,N-dimethylformamide, add 1 g of modified zinc oxide nanoparticles B and ultrasonically disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum dry to obtain a composite boron nitride nanosheet;

[0043] S6: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10 and stir evenly, add 40 g of aqueous acrylic resin solution and stir evenly, add 1 g of the composite boron nitride nanosheet and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0044] Example 3: Preparation process of a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole into deionized water, heat to 180 °C and react for 4 h, cool, perform vacuum filtration under reduced pressure, purify, and freeze-dry to obtain a carbon dot corrosion inhibitor;

[0045] S2: Ultrasonically disperse 80 mg of carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of 0.1 mol / L N-hydroxysuccinimide solution for activation, add 60 mg of dopamine, remove the dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum dry to obtain the modified carbon dot corrosion inhibitor;

[0046] S3: Ultrasonically disperse 5 g of modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an aqueous solution of N,N-dimethylformamide, centrifuge, filter the supernatant under reduced pressure, purify, and vacuum dry to obtain the intercalated modified boron nitride nanosheets;

[0047] S4: Ultrasonically disperse 2 g of zinc oxide nanoparticles in 10 mM Tris-HCl solution, add 2 g of dopamine and 8 g of benzotriazole, react at room temperature for 24 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 1.6 g of KH590, and heat to 80 °C to react for 3 h to obtain modified zinc oxide nanoparticles B;

[0048] S5: Ultrasonically disperse 3 g of intercalated modified boron nitride nanosheets in N,N-dimethylformamide, add 1 g of modified zinc oxide nanoparticles B and disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum dry to obtain the composite boron nitride nanosheets;

[0049] S6: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10 and stir evenly, add 40 g of aqueous acrylic resin solution and stir evenly, add 1 g of composite boron nitride nanosheets and stir evenly to obtain the passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take it out, wash, and dry to obtain the corrosion-resistant galvanized steel pipe.

[0050] Example 4: A preparation process of a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole to deionized water, heat to 180 °C and react for 4 h, cool, filter under reduced pressure, purify, and freeze-dry to obtain the carbon dot corrosion inhibitor;

[0051] S2: Ultrasonically disperse 80 mg of carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of 0.1 mol / L N-hydroxysuccinimide solution for activation, add 75.9 mg of dopamine, remove the dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum dry to obtain the modified carbon dot corrosion inhibitor;

[0052] S3: Ultrasonically disperse 5 g of the modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an aqueous solution of N,N-dimethylformamide, centrifuge, subject the supernatant to reduced-pressure filtration, purify, and vacuum dry to obtain intercalated modified boron nitride nanosheets;

[0053] S4: Ultrasonically disperse 2 g of zinc oxide nanoparticles in a 10 mM Tris-HCl solution, add 3 g of dopamine and 9 g of benzotriazole, react at room temperature for 24 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 3 g of KH590, and react at 80 °C for 3 h to obtain modified zinc oxide nanoparticles B;

[0054] S5: Ultrasonically disperse 3 g of intercalated modified boron nitride nanosheets in N,N-dimethylformamide, add 1 g of modified zinc oxide nanoparticles B and ultrasonically disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum dry to obtain composite boron nitride nanosheets;

[0055] S6: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10 and stir evenly, add 40 g of an aqueous acrylic resin solution and stir evenly, add 1 g of composite boron nitride nanosheets and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse a galvanized steel pipe in the passivation solution for 20 s, take it out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0056] Example 5: A preparation process for a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole to deionized water, heat to 180 °C and react for 4 h, cool, subject to reduced-pressure filtration, purify, and freeze-dry to obtain a carbon dot corrosion inhibitor;

[0057] S2: Ultrasonically disperse 80 mg of the carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of a 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of a 0.1 mol / L N-hydroxysuccinimide solution, activate, add 75.9 mg of dopamine, remove dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum dry to obtain a modified carbon dot corrosion inhibitor;

[0058] S3: Ultrasonically disperse 5 g of the modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an aqueous solution of N,N-dimethylformamide, centrifuge, subject the supernatant to reduced-pressure filtration, purify, and vacuum dry to obtain intercalated modified boron nitride nanosheets;

[0059] S4: Ultrasonically disperse 2 g of zinc oxide nanoparticles in 10 mM Tris-HCl solution, add 3 g of dopamine and 9 g of benzotriazole, react at room temperature for 24 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 3 g of KH590, heat to 80 °C and react for 3 h to obtain modified zinc oxide nanoparticles B;

[0060] S5: Ultrasonically disperse 3 g of intercalated modified boron nitride nanosheets in N,N-dimethylformamide, add 2 g of modified zinc oxide nanoparticles B and disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum dry to obtain composite boron nitride nanosheets;

[0061] S6: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10 and stir evenly, add 40 g of aqueous acrylic resin solution and stir evenly, add 1 g of composite boron nitride nanosheets and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0062] Example 6: A preparation process of a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole to deionized water, heat to 180 °C and react for 4 h, cool, carry out vacuum filtration under reduced pressure, purify, and freeze-dry to obtain a carbon dot corrosion inhibitor;

[0063] S2: Ultrasonically disperse 80 mg of the carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of 0.1 mol / L N-hydroxysuccinimide solution, activate, add 75.9 mg of dopamine, remove the dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum dry to obtain a modified carbon dot corrosion inhibitor;

[0064] S3: Ultrasonically disperse 5 g of the modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an N,N-dimethylformamide aqueous solution, centrifuge, carry out vacuum filtration on the supernatant, purify, and vacuum dry to obtain intercalated modified boron nitride nanosheets;

[0065] S4: Ultrasonically disperse 2 g of zinc oxide nanoparticles in 10 mM Tris-HCl solution, add 3 g of dopamine and 9 g of benzotriazole, react at room temperature for 24 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 3 g of KH590, heat to 80 °C and react for 3 h to obtain modified zinc oxide nanoparticles B;

[0066] S5: Ultrasonically disperse 3 g of intercalated modified boron nitride nanosheets in N,N-dimethylformamide, add 2 g of modified zinc oxide nanoparticles B and disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum dry to obtain composite boron nitride nanosheets;

[0067] S6: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10 and stir evenly, add 40 g of aqueous acrylic resin solution and stir evenly, add 5 g of composite boron nitride nanosheets and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0068] Comparative Example 1: A preparation process for a corrosion-resistant galvanized steel pipe: S1: Ultrasonically disperse 2 g of zinc oxide nanoparticles in 10 mM Tris-HCl solution, add 2 g of dopamine and 8 g of benzotriazole, react at room temperature for 24 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 1.6 g of KH590, heat to 80 °C and react for 3 h to obtain modified zinc oxide nanoparticles B;

[0069] S2: Ultrasonically disperse 3 g of hexagonal boron nitride in N,N-dimethylformamide, add 1 g of modified zinc oxide nanoparticles B and disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum dry to obtain composite boron nitride nanosheets;

[0070] S3: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10 and stir evenly, add 40 g of aqueous acrylic resin solution and stir evenly, add 1 g of composite boron nitride and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0071] Comparative Example 2: Preparation process of a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole into deionized water, heat to 180 °C and react for 4 h, cool, carry out vacuum filtration under reduced pressure, purify, and freeze-dry to obtain a carbon dot corrosion inhibitor;

[0072] S2: Ultrasonically disperse 80 mg of the carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of 0.1 mol / L N-hydroxysuccinimide solution, activate, add 60 mg of dopamine, remove the dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum-dry to obtain a modified carbon dot corrosion inhibitor;

[0073] S3: Ultrasonically disperse 2.5 g of the modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an aqueous solution of N,N-dimethylformamide, centrifuge, carry out vacuum filtration on the supernatant, purify, and vacuum-dry to obtain an intercalated modified boron nitride nanosheet;

[0074] S4: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10, stir evenly, add 40 g of aqueous acrylic resin solution and stir evenly, add 1 g of the intercalated modified boron nitride nanosheet and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take it out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0075] Comparative Example 3: Preparation process of a corrosion-resistant galvanized steel pipe: S1: Add 10 g of glucose, 10 g of anhydrous citric acid, and 8 g of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole into deionized water, heat to 180 °C and react for 4 h, cool, carry out vacuum filtration under reduced pressure, purify, and freeze-dry to obtain a carbon dot corrosion inhibitor;

[0076] S2: Ultrasonically disperse 80 mg of the carbon dot corrosion inhibitor in deionized water, adjust the pH to 6; add 2 mL of 0.1 mol / L 1-ethyl-carbodiimide hydrochloride solution and 2 mL of 0.1 mol / L N-hydroxysuccinimide solution, activate, add 60 mg of dopamine, remove the dissolved oxygen in the reaction system by passing oxygen, stir and react for 3 h, purify, and vacuum-dry to obtain a modified carbon dot corrosion inhibitor;

[0077] S3: Ultrasonically disperse 2.5 g of the modified carbon dot corrosion inhibitor and 2 g of hexagonal boron nitride in an aqueous solution of N,N-dimethylformamide, centrifuge, carry out vacuum filtration on the supernatant, purify, and vacuum-dry to obtain an intercalated modified boron nitride nanosheet;

[0078] S4: Ultrasonically disperse 2 g of zinc oxide nanoparticles in 10 mM Tris-HCl solution, add 2 g of dopamine, react at room temperature for 24 h, purify, and vacuum dry to obtain modified zinc oxide nanoparticles A; ultrasonically disperse 4 g of modified zinc oxide nanoparticles A in N,N-dimethylformamide, add 1.6 g of KH590, heat to 80 °C and react for 3 h to obtain modified zinc oxide nanoparticles B;

[0079] S5: Ultrasonically disperse 3 g of intercalated modified boron nitride nanosheets in N,N-dimethylformamide, add 1 g of modified zinc oxide nanoparticles B and 8 g of benzotriazole, ultrasonically disperse evenly, heat to 105 °C and react for 5 h, purify, and vacuum dry to obtain composite boron nitride nanosheets;

[0080] S6: Dissolve 0.5 g of tannic acid in deionized water, add 0.15 g of fatty alcohol polyoxyethylene ether, 0.15 g of hydroxyethylidene diphosphonic acid, and 0.15 g of emulsifier OP-10, stir evenly, add 40 g of aqueous acrylic resin solution and stir evenly, then add 1 g of composite boron nitride nanosheets and stir evenly to obtain a passivation solution; preheat the passivation solution to 30 °C, immerse the galvanized steel pipe in the passivation solution for 20 s, take it out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe.

[0081] Experiment:

[0082] Copper sulfate drop test: Test according to the standard GB / T 2972-2016. The formula of the copper sulfate solution is: copper sulfate 40 g / L, sodium chloride 35 g / L, hydrochloric acid 15 mL / L. Measure the corrosion resistance of the passivated corrosion-resistant galvanized steel pipe by judging the time when the surface of the sample turns black.

[0083] Neutral salt spray test: Test according to GB / T 1771-2007; the corrosion medium is 5 wt% sodium chloride solution, the temperature is 35 - 37 °C, the humidity is 95%, and the fog deposition rate is 2 mL / (h·cm 2 ); Evaluate according to the standard GB6461-86.

[0084] Table 1 Data table of copper sulfate drop and neutral salt spray test

[0085] Copper sulfate dropping test time / s Salt spray resistance time / h Example 1 75.6 96.1 Example 2 76.4 97.2 Example 3 79.8 98.8 Example 4 80.2 106 Example 5 81.1 112.3 Example 6 82 120.9 Comparative Example 1 64.3 89.6 Comparative Example 2 68 85.7 Comparative Example 3 71.6 86.9

[0086] Conclusion: The corrosion-resistant galvanized steel pipe prepared by the present invention has excellent corrosion resistance, and also has excellent corrosion protection performance under neutral and acidic conditions. In Comparative Example 1, due to the failure to prepare an intercalating agent, in Comparative Example 2, due to the failure to load modified zinc oxide nanoparticles, the corrosion resistance decreased. In Comparative Example 3, due to the failure to load the corrosion inhibitor on the polydopamine-modified nanoparticles, the slow-release effect decreased and the corrosion resistance decreased.

[0087] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A process for preparing a corrosion-resistant galvanized steel pipe, characterized in that: The following steps are involved: S1: Ultrasonic dispersion of zinc oxide nanoparticles in Tris-HCl solution, adding dopamine and corrosion inhibitor solution, reacting at room temperature for 24-26 hours, purifying, and vacuum drying to obtain modified zinc oxide nanoparticles A; ultrasonic dispersion of modified zinc oxide nanoparticles A in N,N-dimethylformamide, adding KH590, heating to 80-85°C and reacting for 3-4 hours to obtain modified zinc oxide nanoparticles B; The corrosion inhibitor is benzotriazole; S2: ultrasonically dispersing the intercalated modified boron nitride nanosheets in N,N-dimethylformamide, adding modified zinc oxide nanoparticles B and ultrasonically dispersing them uniformly, heating to 105-107°C for reaction for 5-6h, purifying, and vacuum drying to obtain composite boron nitride nanosheets; S3: dissolve tannic acid in deionized water, add fatty alcohol polyoxyethylene ether, hydroxyethylidene diphosphonic acid, and emulsifier and stir evenly, add aqueous acrylic resin solution and stir evenly, add composite boron nitride nanosheets and stir evenly to obtain a passivation solution; preheat the passivation solution to 30-32°C, immerse the galvanized steel pipe in the passivation solution for 20-30s, take out, wash, and dry to obtain a corrosion-resistant galvanized steel pipe; The preparation method of the intercalated modified boron nitride nanosheets comprises the following steps: Step (1): adding glucose, anhydrous citric acid and 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole into deionized water, heating to 180-185° C. for reaction for 4-4.5 hours, cooling, vacuum filtering, purification and freeze drying to obtain a carbon dot corrosion inhibitor; Step (2): ultrasonically dispersing the carbon dot corrosion inhibitor in deionized water, adjusting the pH to 6-6.5; adding 1-ethyl-carbodiimide hydrochloride solution and N-hydroxysuccinimide solution to activate, adding dopamine, passing oxygen to remove dissolved oxygen in the reaction system, stirring the reaction for 3-3.5 hours, purifying, and vacuum drying to obtain a modified carbon dot corrosion inhibitor; Step (3): ultrasonically dispersing the modified carbon dot corrosion inhibitor and hexagonal boron nitride in an N,N-dimethylformamide aqueous solution, centrifuging, vacuum filtering the supernatant, purifying, and vacuum drying to obtain intercalated modified boron nitride nanosheets.

2. The process for preparing a corrosion-resistant galvanized steel pipe according to claim 1, characterized in that: In the step of preparing the carbon dot corrosion inhibitor, the mass ratio of glucose: anhydrous citric acid: 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole is 1:1:(0.5-1.2).

3. The process for preparing a corrosion-resistant galvanized steel pipe according to claim 1, characterized in that: In the step of preparing the modified carbon dot corrosion inhibitor, the mass ratio of the carbon dot corrosion inhibitor to dopamine is 80:(60-75.9).

4. The process for preparing a corrosion-resistant galvanized steel pipe according to claim 1, characterized in that: In the step of preparing intercalated modified boron nitride nanosheets, the mass ratio of modified carbon dot corrosion inhibitor: hexagonal boron nitride is (0.25-0.5):0.

2.

5. The process for preparing a corrosion-resistant galvanized steel pipe according to claim 1, characterized in that: In the step of preparing modified zinc oxide nanoparticles A, the mass ratio of zinc oxide nanoparticles: dopamine: corrosion inhibitor in the corrosion inhibitor solution is 2: (2-3): (8-9); In the step of preparing modified zinc oxide nanoparticles B, the mass ratio of modified zinc oxide nanoparticles A:KH590 is (4-5):(1.6-3).

6. The process for preparing a corrosion-resistant galvanized steel pipe according to claim 1, characterized in that: In the step of preparing the composite boron nitride nanosheets, the mass ratio of the intercalated modified boron nitride nanosheets to the modified zinc oxide nanoparticles B is 3:(1-2).

7. The process for preparing a corrosion-resistant galvanized steel pipe according to claim 1, characterized in that: The components in the passivation solution are as follows, by weight: 0.5-0.8 parts of tannic acid, 0.15-0.2 parts of fatty alcohol polyoxyethylene ether, 0.15-0.2 parts of hydroxyethylidene diphosphonic acid, 0.15-0.2 parts of emulsifier, 40-50 parts of aqueous acrylic resin solution, and 1-5 parts of composite boron nitride nanosheets.

8. The process for preparing a corrosion-resistant galvanized steel pipe according to claim 1, characterized in that: The preparation method of the galvanized steel pipe comprises the following steps: subjecting the steel pipe substrate to degreasing, water washing, pickling and water washing pretreatment in sequence; placing the pretreated steel pipe in a chemical plating solution, heating it to 50-55° C. and performing constant temperature chemical galvanizing for 10-15 minutes to obtain a galvanized steel pipe; wherein the solution used in the degreasing step is a 10wt% sodium hydroxide solution, and the solution used in the pickling step is a 16wt% hydrochloric acid solution; the thickness of the zinc coating of the galvanized steel pipe is 8-9μm.

9. A corrosion-resistant galvanized steel pipe prepared according to the preparation process of a corrosion-resistant galvanized steel pipe according to any one of claims 1 to 8.