High-temperature-resistant steel pipe anticorrosive paint and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant steel pipe anticorrosive coating and a preparation method thereof, and relates to the technical field of coatings. The high-temperature-resistant steel pipe anticorrosive paint is prepared from reinforcement modified silica sol, titanium dioxide, mica powder, a BYK-323 flatting agent and an FLOWLENAC-300 defoaming agent. A silicon carbide and carbon shell / reduced graphene oxide composite powder filler is used as a reinforcing body and is embedded into silica sol under the crosslinking effect, reinforcing body modified silica sol is formed, a highly-crosslinked and compact organic-inorganic hybrid composite network structure is presented, and then the reinforcing body modified silica sol is used as a continuous matrix of the coating to play a core role; the high temperature resistance and corrosion resistance of the coating are improved, the interface bonding force among the components can be enhanced, agglomeration and sedimentation of the filler in the storage and curing process are effectively prevented, the micropore defect is reduced, and the effectiveness and durability of protection of the high-temperature-resistant and corrosion-resistant coating are further enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coatings, and particularly relates to a high-temperature-resistant steel pipe anticorrosive coating and a preparation method thereof. BACKGROUND

[0002] Metal corrosion is a global problem, which not only leads to waste of metal resources, but also has a negative impact on the environment, so it is crucial to protect the metal, and the anticorrosive coating is an effective protection method, which can effectively prevent the penetration of corrosive media by forming a dense protective film on the surface of the metal, and the high-temperature-resistant anticorrosive coating is a coating with both high-temperature resistance and corrosion resistance, which can be used for a long time under certain high-temperature conditions to protect the base material and reduce the corrosion of corrosive media, so that the equipment and facilities can operate safely within the maintenance period.

[0003] The existing technology mainly has the following problems:

[0004] The traditional anticorrosive coating has poor high-temperature resistance, and is prone to produce micropore defects in the curing process, which reduces the anticorrosive ability, and thus it is difficult to meet the protection requirements in the high-temperature anticorrosive environment. SUMMARY

[0005] In view of the above problems, the present application provides a high-temperature-resistant steel pipe anticorrosive coating, which comprises the following components in parts by weight: 90-100 parts of reinforcing modified silica sol, 15-25 parts of titanium white, 10-15 parts of mica powder, 0.2-0.4 parts of BYK-323 leveling agent, and 0.4-0.8 parts of FLOWLENAC-300 defoaming agent.

[0006] The reinforcing modified silica sol is prepared from the following components in parts by weight: 10-15 parts of sodium fluorosilicate, 20-25 parts of 3-mercaptopropyl triethoxysilane, 3-5 parts of vinyl triethoxysilane, 160-180 parts of isopropyl alcohol, 10-15 parts of silicon carbide@carbon shell / reduced graphene oxide composite powder filler, 0.5-0.7 parts of hydrochloric acid, and 28-32 parts of polysilicate.

[0007] The silicon carbide@carbon shell / reduced graphene oxide composite powder filler is prepared from the following components in parts by weight: 8-10 parts of nano silicon carbide, 3-5 parts of polyethyleneimine, 4-5 parts of 3-aminopropyl triethoxysilane, and 2-3 parts of graphene oxide.

[0008] The preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler specifically comprises the following steps:

[0009] (1) 0.8-1.0 g of nano silicon carbide is added to a round-bottom flask containing 50 mL of anhydrous ethanol, and ultrasonic oscillation is performed for 30-40 min to obtain a nano silicon carbide dispersion solution for use, at the same time, polyethyleneimine with a molecular weight of 3500-7500 is dissolved in 20 mL of a 95% ethanol solution and the pH is adjusted to 4.0-5.0 using acetic acid, then 1-2 drops of the nano silicon carbide dispersion solution is added per second, after the dropwise addition is completed, the round-bottom flask is immersed in a constant-temperature water bath at 40-45°C, and the reaction is performed under magnetic stirring for 12-24 h, centrifugal separation is performed, the supernatant is removed, and then the ethanol solution is added again to 70 mL, ultrasonic oscillation is performed for 3-5 min, then centrifugal separation is performed, and this process is repeated 3-5 times, finally, the precipitate is dried in a vacuum drying oven at 60-80°C, an organic coating layer is formed on the surface of the polyethyleneimine, and a steric hindrance effect is generated, which reduces the agglomeration between the nano silicon carbide particles, enables the nano silicon carbide to be uniformly dispersed in the coating matrix, and thus effectively fills the pores in the coating curing, better plays the high-temperature resistance and corrosion resistance of silicon carbide itself, and polyethyleneimine-modified silicon carbide is obtained;

[0010] (2) The polyethyleneimine-modified silicon carbide obtained in step (1) is dispersed in 80-100 mL of a 75% ethanol solution, ultrasonic dispersion treatment is performed for 0.5-1 h to obtain a dispersion solution for use, 3-aminopropyl triethoxysilane is added to 50 mL of anhydrous ethanol, and the pH is adjusted to 3.0-4.0 using glacial acetic acid to obtain a hydrolysis solution for use, then the dispersion solution is slowly added to the hydrolysis solution under stirring at a speed of 300-500 rpm, stirring is performed for 0.5-1 h, then the reaction is performed in a constant-temperature water bath at 65-75°C for 3-4 h, centrifugal separation is performed, the precipitate is redispersed in an ethanol solution and centrifuged for 2-3 times, and the washed precipitate is dried in a vacuum drying oven at 60-80°C, the silicon alcohol group generated after the hydrolysis of 3-aminopropyl triethoxysilane not only forms a firm and heat-resistant Si-O-Si covalent bond with the hydroxyl group on the surface of the silicon carbide particles, but also stabilizes the precursor structure, fixes the polyethyleneimine on the surface of the silicon carbide, and ensures the durability of the entire core-shell structure in a high-temperature environment, at the same time, the intervention of 3-aminopropyl triethoxysilane not only reduces the original agglomeration of the fillers due to the entanglement and adhesion of the polyethyleneimine chain segments during the processing process, enables the fillers to fully penetrate and fill the nanoscale micropores formed by the polymer molecular chains, but also greatly increases the surface amino group density and uniformity on the polyethyleneimine layer which is already rich in amino groups, which is beneficial to optimizing the interface bonding between the fillers and between the fillers and the matrix, and such stronger interface interaction helps to prevent the agglomeration and sedimentation of the fillers during the storage and curing of the coating, reduces the occurrence of micropore defects, and silanized polyethyleneimine-modified silicon carbide is obtained;

[0011] (3) 0.1-0.3 g of the silanized polyethyleneimine modified silicon carbide from step (2) is weighed into 200 mL N,N-dimethylacetamide solvent, and ultrasonic dispersion is performed for 20-30 min to obtain a silanized polyethyleneimine modified silicon carbide dispersion liquid, which is used as received. Graphene oxide is dispersed in 200 mL N,N-dimethylacetamide solvent, and ultrasonic dispersion is performed for 30-40 min. Then, 0.2-0.3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 0.10-0.18 g of N-hydroxysuccinimide are added, and stirring is performed at room temperature for 1-2 h to obtain an activated suspension, which is used as received. Then, the activated suspension is added to the silanized polyethyleneimine modified silicon carbide dispersion liquid, and transferred to a 100-105 °C oil bath, and constant temperature stirring is performed for 3-4 h. Finally, centrifugation is performed, the precipitate is washed with anhydrous ethanol for 2-3 times, vacuum dried, and ground. After activation of the graphene oxide, the carboxyl groups on the surface form amide bonds with the amino groups of the silanized polyethyleneimine modified silicon carbide, and the two together construct a stable heat-resistant network, enhancing the integrity of the heat-resistant barrier of the coating, preventing the coating from flowing, bubbling, or large-area cracking, and thus improving the high-temperature resistance of the coating. Moreover, this stable covalent bond eliminates the risk of weak interfacial bonding, so that the corrosion medium cannot penetrate from the interface between the two, and the synergistic effect of the nanoscale particles and the micrometer-scale sheets realizes all-around, dead-angle-free filling from the nanometer to the micrometer scale, thereby reducing the occurrence of micropore defects and improving the corrosion resistance. The composite powder is obtained;

[0012] (4) The composite powder from step (3) is placed in a tube furnace, and heated to 300-400 °C at a rate of 2-5 °C / min under an argon atmosphere, and held for 1-2 h. In this process, the graphene oxide is converted into reduced graphene oxide, and the thermal stability and chemical stability are further improved. At the same time, the polyethyleneimine and 3-aminopropyltriethoxysilane pyrolyze and form an amorphous carbon shell at the interface between the silicon carbide particles and the reduced graphene oxide sheets, more firmly connecting the silicon carbide particles and the reduced graphene oxide sheets together, and the amorphous carbon shell formed is more resistant to high temperature and corrosion than the amide bond alone. Moreover, the amorphous carbon shell further eliminates the small defects at the interface, making the penetration path of the corrosion medium more tortuous and difficult, and also providing a complete and stable skeleton support at high temperatures. The silicon carbide@carbon shell / reduced graphene oxide composite powder filler is obtained;

[0013] Preferably, in step (1), the amount of polyethyleneimine added is 0.3-0.5 g. The polyethyleneimine provides amino active sites, which can strengthen the interfacial bonding within the filler and play a positive role as a molecular bridge between materials.

[0014] Preferably, in step (2), the amount of 3-aminopropyl triethoxysilane added is 0.4-0.5 mL, and the other end of the 3-aminopropyl triethoxysilane is an amino group, which further increases the amino group density and reactivity of the particle surface, and is beneficial to the grafting efficiency and strength with graphene oxide in the subsequent step;

[0015] Preferably, in step (3), the amount of graphene oxide added is 0.2-0.3 g, and the graphene oxide has good thermal stability, and its two-dimensional sheet structure not only extends and tortuously the penetration path of the corrosion medium, but also laps, covers and blocks on the micropores or defects, thereby improving the micropores in the coating.

[0016] The application also provides a preparation method of a high-temperature-resistant steel pipe anticorrosive coating, which specifically comprises the following steps:

[0017] S1, 10.0-15.0 g of sodium fluorosilicate, 20.0-25.0 g of 3-mercapto propyl triethoxysilane and 3.0-5.0 g of vinyl triethoxysilane are added to 160.0-180.0 g of isopropyl alcohol, a high-speed shearing disperser is used to stir at a speed of 600-800 rpm for 20-30 min, 10.0-15.0 g of silicon carbide@carbon shell / reduced graphene oxide composite powder filler is added at a speed of 1000-2000 rpm, the speed is adjusted to 8000-12000 rpm, and mixing is performed for 20-40 min, then 5.0-7.0 g of 10% hydrochloric acid aqueous solution is added, the reaction temperature is controlled at 35-40℃, 100 mL of polysilicate pre-hydrolyzate is slowly added under stirring at a speed of 600-800 rpm within 5 h, the viscosity of the system is monitored and adjusted to 1000-1500 mPa·s during the period, after complete addition, stirring is continued for 1-2 h, in the insulating silicon sol matrix, the silicon carbide@carbon shell / reduced graphene oxide composite powder filler acts as a reinforcing body, and a highly cross-linked and dense organic-inorganic hybrid composite network structure is formed through silane chemical cross-linking, a dense physical and chemical barrier is constructed, excellent high-temperature resistance and corrosion resistance are presented, and the re-agglomeration of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler can be effectively prevented, the interface micropores and defects generated due to re-agglomeration in the coating curing process are eliminated, and a reinforcing body modified silicon sol is obtained;

[0018] S2, the reinforcing body modified silica sol and titanium white powder, mica powder, BYK-323 leveling agent, FLOWLENAC-300 defoaming agent described in step S1 are treated by ball milling with a horizontal ball mill, wherein the ball-to-material ratio is 2-3:1, the ball milling time is 4-8h, the material temperature is controlled at 34-38 DEG C, the particle fineness is ensured to be not more than 20 mu m, the reinforcing body modified silica sol serves as a continuous matrix of the coating, provides film-forming property, adhesion, high temperature resistance and physical and chemical protection, other fillers and additives are dispersed therein, and the protective performance and workability are synergistically enhanced, so that the coating simultaneously has the high temperature resistance and corrosion resistance of inorganic materials and the flexibility and strong adhesion of organic materials, and is particularly suitable for steel pipe protection in harsh environments such as high temperature and corrosion, and a high temperature resistant steel pipe anticorrosion coating is obtained;

[0019] Preferably, in step S1, the polysilicate pre-hydrolysis solution contains 28.0-32.0g polysilicate, the polysilicate is a precursor of inorganic silica network, and the silica network formed after solidification is an inorganic glassy structure with extremely high melting point, which improves the high temperature resistance of the coating, and the silica network not only has excellent resistance to most acids, solvents and chemical media, but also reduces the penetration of corrosive media through its low permeability structure, thereby providing stronger corrosion resistance.

[0020] The beneficial effects obtained by the application are as follows:

[0021] The application forms a reinforced body modified silica sol by embedding the silicon carbide@carbon shell / reduced graphene oxide composite powder filler as a reinforcing body into the silica sol by cross-linking, presents a highly cross-linked and dense organic-inorganic hybrid composite network structure, and then plays a core role as a continuous matrix of the coating, not only improves the high temperature resistance and corrosion resistance of the coating, but also enhances the interface bonding force between the components, effectively prevents the filler from agglomeration and sedimentation during storage and curing process, reduces the occurrence of micropore defects, and further enhances the effectiveness and durability of the high temperature resistant and corrosion resistant coating protection; in the silicon carbide@carbon shell / reduced graphene oxide composite powder filler, the silicon carbide is taken as the core, the polyethyleneimine and 3-aminopropyl triethoxysilane in the middle layer are pyrolyzed to form an amorphous carbon shell layer which is more resistant to high temperature and corrosion, and the silicon carbide particles and reduced graphene oxide sheet are firmly connected together, and the dense carbon shell formed at the same time further eliminates the micro defects at the interface, so that the penetration path of the corrosion medium is more tortuous and difficult, and the complete and stable skeleton support can be provided at high temperature, the high temperature resistance and corrosion resistance of the composite powder are improved, furthermore, the optimized internal sintering treatment makes the structure of the composite powder more compact and less defective, eliminates the internal micropore defects of the composite powder itself, and further forms a more stable and less deformed microstructure during the curing process of the coating, and reduces the micropores generated by shrinkage during curing; in the reinforced body modified silica sol, the silicon hydroxyl groups of 3-mercaptopropyl triethoxysilane and vinyl triethoxysilane can not only react with polysilicate to form a continuous and high cross-linking degree Si-O-Si three-dimensional network structure with excellent high temperature resistance and corrosion resistance, but also form a firm Si-O-C covalent bond with the surface of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler, which is equivalent to grafting a plurality of flexible silane molecular chains on the surface of the filler particles, and the other end of the molecular chain is embedded into the entire three-dimensional silica sol network, thereby enhancing the interface bonding force between the filler and the matrix, greatly reducing the interface micropores and defects, realizing seamless connection, effectively preventing the invasion of the corrosion medium from the interface, and at the same time, destroying the continuous conductive network formed between the reduced graphene oxide sheet, thereby eliminating the risk of electrochemical corrosion, and significantly improving the protection ability of the steel pipe in high temperature and corrosion environment; the application forms a high temperature resistant steel pipe anticorrosion coating by using the reinforced body modified silica sol, titanium white powder, mica powder, BYK-323 leveling agent and FLOWLENAC-300 defoaming agent, effectively improves the occurrence of micropore defects, significantly improves the high temperature resistance and corrosion resistance of the coating, and enhances the effectiveness and durability of the protection effect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The high temperature limit result graph of examples 1-4 and comparative examples 1-3 of the application;

[0023] Figure 2Corrosion maximum length results chart for examples 1-4 and comparative examples 1-3 of the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art. In addition, any method and material similar or equivalent to those described herein can be used in the present application. The preferred implementation methods and materials described herein are only used for demonstration, but cannot limit the content of the present application.

[0026] The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The experimental materials used in the following embodiments are all purchased from commercial channels unless otherwise specified.

[0027] Example 1

[0028] The present embodiment proposes a high-temperature-resistant steel pipe anticorrosive coating, which comprises the following components by weight: 100 parts of reinforcing modified silica sol, 25 parts of titanium white, 15 parts of mica powder, 0.4 parts of BYK-323 leveling agent, and 0.8 parts of FLOWLENAC-300 defoaming agent.

[0029] The reinforcing modified silica sol is made of the following components by weight: 15 parts of sodium fluorosilicate, 25 parts of 3-mercaptopropyl triethoxysilane, 5 parts of vinyl triethoxysilane, 180 parts of isopropyl alcohol, 15 parts of silicon carbide@carbon shell / reduced graphene oxide composite powder filler, 0.7 parts of hydrochloric acid, and 32 parts of polysilicate.

[0030] The silicon carbide@carbon shell / reduced graphene oxide composite powder filler is made of the following components by weight: 10 parts of nano silicon carbide, 5 parts of polyethyleneimine, 5 parts of 3-aminopropyl triethoxysilane, and 3 parts of graphene oxide.

[0031] The preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler specifically comprises the following steps:

[0032] (1) 1.0 g of nanometer silicon carbide was added to a round-bottom flask containing 50 mL of anhydrous ethanol, and ultrasonic oscillation was performed for 40 min to obtain a nanometer silicon carbide dispersion liquid for use, at the same time, 0.5 g of polyethyleneimine with a molecular weight of 7500 was dissolved in 20 mL of a 95% ethanol solution and adjusted to a pH of 5.0 using acetic acid, the polyethyleneimine provided an amino active site and could strengthen the internal interface bonding of the filler and played an active role as a molecular bridge between materials, then 1 drop / second of the nanometer silicon carbide dispersion liquid was added thereto, after the dropwise addition was completed, the round-bottom flask was immersed in a constant-temperature water bath at 45°C and reacted for 24 h under magnetic stirring, centrifugal separation was performed, after the supernatant was removed, ethanol solution was again added to 70 mL, ultrasonic oscillation was performed for 5 min, then centrifugal separation was performed, and this process was repeated 5 times, finally, the precipitate was dried in a vacuum drying oven at 80°C, the polyethyleneimine formed an organic coating layer on the surface of the nanometer silicon carbide and produced a steric hindrance effect, reducing the agglomeration between nanometer silicon carbide particles, enabling them to be uniformly dispersed in the coating matrix, thereby effectively filling pores in the curing of the coating, better playing the high-temperature resistance and corrosion resistance of silicon carbide itself, and obtaining polyethyleneimine-modified silicon carbide;

[0033] (2) The polyethyleneimine modified silicon carbide of step (1) is dispersed in 100 mL of 75% ethanol solution, and ultrasonic dispersion treatment is performed for 1 h to obtain a dispersion liquid for use, 3-aminopropyl triethoxysilane is added to 50 mL of anhydrous ethanol, and the amount of 3-aminopropyl triethoxysilane added is 0.5 mL, the other end of 3-aminopropyl triethoxysilane is an amino group, which further increases the amino group density and reactivity of the particle surface, and is conducive to the grafting efficiency and strength of the subsequent graphene oxide, and glacial acetic acid is used to adjust the pH to 4.0 to obtain a hydrolysis liquid for use, then the dispersion liquid is slowly added to the hydrolysis liquid under stirring at a speed of 500 rpm, stirring is performed for 1 h, and then reaction is performed in a constant temperature water bath at 75°C for 4 h, centrifugation is performed, the precipitate is redispersed in an ethanol solution and centrifuged for 3 times, the precipitate after washing is dried in a vacuum drying oven at 80°C, the silanol groups after hydrolysis of 3-aminopropyl triethoxysilane can form a firm and heat-resistant Si-O-Si covalent bond with the hydroxyl groups on the surface of the silicon carbide particles, and the structure of the precursor is stabilized, the polyethyleneimine is fixed on the surface of the silicon carbide, and the durability of the entire core-shell structure in a high-temperature environment is ensured, at the same time, the intervention of 3-aminopropyl triethoxysilane not only reduces the problem of filler original agglomeration caused by entanglement and adhesion of the polyethyleneimine chain segment in the processing process, so that it fully penetrates and fills into the nanoscale small pores formed by the polymer molecular chain, but also greatly increases the surface amino group density and uniformity on the polyethyleneimine layer which is already rich in amino groups, which is conducive to optimizing the interface bonding between fillers and between fillers and the matrix, and this stronger interface interaction helps to prevent the filler from agglomerating and settling during paint storage and curing, reduces the occurrence of micropore defects, and obtains silanized polyethyleneimine modified silicon carbide;

[0034] (3) 0.3 g of the silanized polyethyleneimine modified silicon carbide in step (2) is weighed into 200 mL of N,N-dimethylacetamide solvent, and ultrasonic dispersion is performed for 30 min to obtain a silanized polyethyleneimine modified silicon carbide dispersion liquid, which is used as received. Graphene oxide is dispersed in 200 mL of N,N-dimethylacetamide solvent, and the amount of graphene oxide added is 0.3 g. The graphene oxide has good thermal stability, and its two-dimensional sheet structure not only extends and zigzags the penetration path of the corrosion medium, but also overlaps, covers, and blocks the micro pores or defects, thereby improving the micro pores in the coating. Ultrasonic dispersion is performed for 40 min, then 0.3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 0.18 g of N-hydroxysuccinimide are added, and stirring is performed at room temperature for 2 h to obtain an activated suspension, which is used as received. Then, the activated suspension is added to the silanized polyethyleneimine modified silicon carbide dispersion liquid, and transferred to an oil bath at 105°C, and constant temperature stirring is performed for 4 h. Finally, centrifugation is performed, the precipitate is washed with anhydrous ethanol for 3 times, vacuum dried, ground, and the like. After the graphene oxide is activated, the carboxyl groups on the surface form amide bonds with the amino groups of the silanized polyethyleneimine modified silicon carbide, and the two together construct a stable heat-resistant network, which enhances the integrity of the heat-resistant barrier of the coating, prevents the coating from flowing, bubbling, or large-area cracking, and further improves the high-temperature resistance of the coating. In addition, this stable covalent bond eliminates the risk of weak interfacial bonding, so that the corrosion medium cannot penetrate from the interface between the two, and the synergistic effect of the nanoscale particles and the micrometer-scale sheets realizes all-around, dead-angle-free filling from the nanometer to the micrometer scale, thereby reducing the occurrence of micro-pore defects and improving the corrosion resistance. A composite powder is obtained.

[0035] (4) The composite powder in step (3) is placed in a tube furnace, and heated to 400°C at a rate of 5°C / min under the protection of an argon atmosphere, and held for 2 h. In this process, the graphene oxide is converted into reduced graphene oxide, and the thermal stability and chemical stability of the reduced graphene oxide are further improved. At the same time, the polyethyleneimine and 3-aminopropyltriethoxysilane pyrolyze and form an amorphous carbon shell at the interface between the silicon carbide particles and the reduced graphene oxide sheets, which more firmly connects the silicon carbide particles and the reduced graphene oxide sheets together, and is more resistant to high temperature and corrosion than the amide bond alone. In addition, the dense carbon shell further eliminates the micro defects at the interface, making the penetration path of the corrosion medium more tortuous and difficult, and also providing a complete and stable skeleton support at high temperatures. A silicon carbide@carbon shell / reduced graphene oxide composite powder filler is obtained.

[0036] The embodiment provides a preparation method of a high-temperature-resistant steel pipe anticorrosive coating, and specifically includes the following steps:

[0037] S1, 15.0 g of sodium fluorosilicate, 25.0 g of 3-mercaptopropyl triethoxysilane, and 5.0 g of vinyl triethoxysilane are added to 180.0 g of isopropyl alcohol, stirred at a speed of 800 rpm for 30 min using a high-speed shearing disperser, 15.0 g of silicon carbide@carbon shell / reduced graphene oxide composite powder filler is added at a speed of 2000 rpm, the speed is adjusted to 12000 rpm, and mixed for 40 min, then 7.0 g of 10% mass fraction hydrochloric acid aqueous solution is added, the reaction temperature is controlled at 40℃, 100 mL of polysilicate pre-hydrolysate containing 32.0 g of polysilicate is slowly added at a stirring speed of 800 rpm within 5 h, the polysilicate is the precursor of the inorganic silica network, and the silica network formed after curing is an inorganic glassy structure with a very high melting point, which improves the high temperature resistance of the coating. At the same time, the silica network not only has excellent resistance to most acids, solvents and chemical media, but also reduces the penetration of corrosive media through its low permeability structure, providing stronger corrosion resistance. The viscosity of the system is monitored and adjusted to 1500 mPa·s during the period. After complete addition, continue to stir for 2 h. In the insulating silica sol matrix, the silicon carbide@carbon shell / reduced graphene oxide composite powder filler acts as a reinforcing agent, and a highly cross-linked and dense organic-inorganic hybrid composite network structure is formed through silane chemical cross-linking, building a dense physical and chemical barrier, showing excellent high temperature resistance, corrosion resistance, and effectively preventing the re-agglomeration of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler, eliminating the interface micropores and defects caused by agglomeration during coating curing, and obtaining a reinforcing agent modified silica sol;

[0038] S2, the reinforcing agent modified silica sol, titanium dioxide, mica powder, BYK-323 leveling agent, and FLOWLENAC-300 defoaming agent described in step S1 are ball milled using a horizontal ball mill, wherein the ball-to-material ratio is 3:1, the ball milling time is 8 h, and the material temperature is controlled at 38℃ to ensure that the particle size is not more than 20 μm. The reinforcing agent modified silica sol acts as a continuous matrix of the coating, providing film forming property, adhesion, high temperature resistance, and physical and chemical protection, and the other fillers and additives are dispersed therein, synergistically enhancing the protective performance and workability, so that the coating has both the high temperature resistance and corrosion resistance of inorganic materials and the flexibility and strong adhesion of organic materials, and is particularly suitable for steel pipe protection in harsh environments such as high temperature and corrosion. A high temperature resistant steel pipe anti-corrosion coating is obtained.

[0039] Example 2

[0040] The present embodiment provides a high temperature resistant steel pipe anti-corrosion coating, which comprises the following components by weight: 95 parts of reinforcing agent modified silica sol, 20 parts of titanium dioxide, 12.5 parts of mica powder, 0.3 parts of BYK-323 leveling agent, and 0.6 parts of FLOWLENAC-300 defoaming agent.

[0041] The reinforcing body modified silica sol is made of the following components by weight: sodium fluorosilicate 12.5 parts, 3-mercaptopropyl triethoxysilane 22.5 parts, vinyl triethoxysilane 4 parts, isopropyl alcohol 170 parts, silicon carbide@carbon shell / reduced graphene oxide composite powder filler 12.5 parts, hydrochloric acid 0.6 parts, polysilicate 30 parts.

[0042] The silicon carbide@carbon shell / reduced graphene oxide composite powder filler is made of the following components by weight: nano silicon carbide 9 parts, polyethyleneimine 4 parts, 3-aminopropyl triethoxysilane 4.5 parts, graphene oxide 2.5 parts.

[0043] The preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler specifically includes the following steps:

[0044] (1) 0.9 g of nano silicon carbide is added to a round-bottom flask containing 50 mL of anhydrous ethanol, and ultrasonic oscillation is performed for 35 min to obtain a nano silicon carbide dispersion liquid for later use. Meanwhile, polyethyleneimine with a molecular weight of 5500 is dissolved in 20 mL of an ethanol solution with a mass fraction of 95%, and acetic acid is used to adjust the pH to 4.5. The addition amount of polyethyleneimine is 0.4 g. The polyethyleneimine provides an amino active site, which can strengthen the internal interface bonding of the filler and play a positive role as a molecular bridge between materials. Then, 2 drops of the nano silicon carbide dispersion liquid are added per second. After the dropwise addition is completed, the round-bottom flask is immersed in a constant-temperature water bath at 42.5°C, and the reaction is performed under magnetic stirring for 18 h. After centrifugal separation, the supernatant is removed, and then the ethanol solution is supplemented to 70 mL. Ultrasonic oscillation is performed for 4 min, followed by centrifugal separation. This process is repeated 4 times. Finally, the precipitate is dried in a vacuum drying oven at 70°C. The polyethyleneimine forms an organic coating layer on the surface of the nano silicon carbide and produces a steric hindrance effect, reducing the agglomeration between the nano silicon carbide particles, so that they can be uniformly dispersed in the coating matrix, thereby effectively filling the pores in the coating curing and better exerting the high-temperature resistance and corrosion resistance of silicon carbide itself, to obtain polyethyleneimine-modified silicon carbide;

[0045] (2) The polyethyleneimine modified silicon carbide of step (1) is dispersed in 90 mL of 75% mass fraction ethanol solution, ultrasonic dispersion treatment is performed for 0.75 h, to obtain a dispersion liquid for standby use, 3-aminopropyl triethoxysilane is added to 50 mL of anhydrous ethanol, the addition amount of 3-aminopropyl triethoxysilane is 0.45 mL, the other end of 3-aminopropyl triethoxysilane is an amino group, which further increases the amino group density and reactivity of the particle surface, and is conducive to the grafting efficiency and strength with graphene oxide in the subsequent process, and glacial acetic acid is used to adjust the pH to 3.5 to obtain a hydrolysis liquid for standby use, then the dispersion liquid is slowly added to the hydrolysis liquid under stirring at a speed of 400 rpm, stirring is performed for 0.75 h, and then reaction is performed in a constant temperature water bath at 70°C for 3.5 h, centrifugation is performed, the precipitate is redispersed in an ethanol solution and centrifuged twice, the precipitate after washing is dried in a vacuum drying oven at 70°C, the silanol groups after hydrolysis of 3-aminopropyl triethoxysilane can not only form a firm and heat-resistant Si-O-Si covalent bond with the hydroxyl groups on the surface of the silicon carbide particles, but also stabilize the precursor structure, fix the polyethyleneimine on the surface of the silicon carbide, and ensure the durability of the entire core-shell structure in a high-temperature environment, at the same time, the intervention of 3-aminopropyl triethoxysilane not only reduces the problem of filler original agglomeration caused by entanglement and adhesion of the polyethyleneimine chain segment in the processing process, so that it fully penetrates and fills into the nanoscale small pores formed by the polymer molecular chain, but also greatly increases the surface amino group density and uniformity on the polyethyleneimine layer which is already rich in amino groups, which is conducive to optimizing the interface bonding between fillers and between fillers and the matrix, and this stronger interface interaction helps to prevent the agglomeration and sedimentation of fillers during paint storage and curing, reduces the occurrence of micropore defects, and obtains silanized polyethyleneimine modified silicon carbide;

[0046] (3) 0.2 g of the silanized polyethyleneimine modified silicon carbide in step (2) is added into 200 mL of N,N-dimethylacetamide solvent, and ultrasonic dispersion is performed for 25 min to obtain a silanized polyethyleneimine modified silicon carbide dispersion liquid, which is used as received. Graphene oxide is dispersed in 200 mL of N,N-dimethylacetamide solvent, and the amount of graphene oxide added is 0.25 g. The graphene oxide has good thermal stability, and its two-dimensional sheet structure can not only extend and zigzag the penetration path of the corrosion medium, but also lap, cover and block on the micropores or defects to improve the micropores in the coating. Ultrasonic dispersion is performed for 35 min, then 0.25 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 0.14 g of N-hydroxysuccinimide are added, and stirring is performed at room temperature for 1.5 h to obtain an activated suspension, which is used as received. Then, the activated suspension is added to the silanized polyethyleneimine modified silicon carbide dispersion liquid, and is transferred to an oil bath at 102.5°C for constant temperature stirring reaction for 3.5 h. Finally, centrifugation is performed, the precipitate is washed twice with anhydrous ethanol, vacuum drying is performed, and grinding is performed. After the graphene oxide is activated, the carboxyl groups on the surface form amide bonds with the amino groups of the silanized polyethyleneimine modified silicon carbide, and the two together construct a stable heat-resistant network, which enhances the integrity of the heat-resistant barrier of the coating, prevents the coating from flowing, bubbling or large-area cracking, and thus improves the high-temperature resistance of the coating. In addition, the stable covalent bonding eliminates the risk of weak interfacial bonding, so that the corrosion medium cannot penetrate from the interface between the two, and the synergistic effect of the nanoscale particles and the micrometer-scale sheets realizes all-around and dead-angle-free filling from the nanometer to the micrometer scale, thereby reducing the occurrence of micropore defects and improving the corrosion resistance. A composite powder is obtained.

[0047] (4) The composite powder in step (3) is placed in a tube furnace, and is heated to 350°C at a rate of 3.5°C / min under the protection of an argon atmosphere, and is kept at this temperature for 1.5 h. In this process, the graphene oxide is converted into reduced graphene oxide, and the thermal stability and chemical stability of the reduced graphene oxide are further improved. At the same time, the polyethyleneimine and 3-aminopropyltriethoxysilane pyrolyze and form an amorphous carbon shell at the interface between the silicon carbide and the reduced graphene oxide, which more firmly connects the silicon carbide particles and the reduced graphene oxide sheets together, and is more resistant to high temperature and corrosion than the amide bond alone. In addition, the dense carbon shell further eliminates the small defects at the interface, making the penetration path of the corrosion medium more tortuous and difficult, and also providing a complete and stable skeleton support at high temperature. A silicon carbide@carbon shell / reduced graphene oxide composite powder filler is obtained.

[0048] The embodiment provides a preparation method of a high-temperature-resistant steel pipe anticorrosive coating, and specifically comprises the following steps:

[0049] S1, 12.5 g of sodium fluorosilicate, 22.5 g of 3-mercaptopropyl triethoxysilane, and 4.0 g of vinyl triethoxysilane are added to 170.0 g of isopropyl alcohol, and stirred at a speed of 700 rpm for 25 min using a high-speed shearing disperser, 12.5 g of silicon carbide@carbon shell / reduced graphene oxide composite powder filler is added at a speed of 1500 rpm, the speed is adjusted to 10000 rpm, and mixed for 30 min, then 6.0 g of 10% mass fraction hydrochloric acid aqueous solution is added, the reaction temperature is controlled at 37.5℃, 100 mL of polysilicate pre-hydrolysate containing 30.0 g of polysilicate is slowly added at a stirring speed of 700 rpm within 5 h, the polysilicate is the precursor of the inorganic silica network, and the silica network formed after curing is an inorganic glassy structure with extremely high melting point, which improves the high temperature resistance of the coating, at the same time, the silica network not only has excellent resistance to most acids, solvents and chemical media, but also reduces the penetration of corrosive media through its low permeability structure, providing stronger corrosion resistance, the viscosity of the system is monitored and adjusted to 1250 mPa·s during the period, after complete addition, the stirring reaction is continued for 1.5 h, in the insulating silica sol matrix, the silicon carbide@carbon shell / reduced graphene oxide composite powder filler acts as a reinforcing body, and a highly cross-linked and dense organic-inorganic hybrid composite network structure is formed through silane chemical cross-linking, a dense physical and chemical barrier is constructed, excellent high temperature resistance and corrosion resistance are presented, and the re-agglomeration of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler is effectively prevented, eliminating the interface micropores and defects caused by agglomeration during coating curing, and obtaining a reinforcing body modified silica sol;

[0050] S2, the reinforcing body modified silica sol, titanium dioxide, mica powder, BYK-323 leveling agent, and FLOWLENAC-300 defoaming agent described in step S1 are ball milled using a horizontal ball mill, wherein the ball-to-material ratio is 2.5:1, the ball milling time is 6 h, and the material temperature is controlled at 36℃, ensuring that the particle size is not more than 20 μm, the reinforcing body modified silica sol acts as a continuous matrix of the coating, providing film forming property, adhesion, high temperature resistance, and physical and chemical protection, and the other fillers and additives are dispersed therein, synergistically enhancing the protection performance and workability, so that the coating simultaneously has the high temperature resistance and corrosion resistance of inorganic materials and the flexibility and strong adhesion of organic materials, and is particularly suitable for steel pipe protection in harsh environments such as high temperature and corrosion, and a high temperature resistant steel pipe anti-corrosion coating is obtained.

[0051] Example 3

[0052] The present embodiment provides a high temperature resistant steel pipe anti-corrosion coating, which comprises the following components by weight: 90 parts of reinforcing body modified silica sol, 15 parts of titanium dioxide, 10 parts of mica powder, 0.2 parts of BYK-323 leveling agent, and 0.4 parts of FLOWLENAC-300 defoaming agent.

[0053] The reinforcing body modified silica sol is made of the following components by weight: sodium fluorosilicate 10 parts, 3-mercaptopropyl triethoxysilane 20 parts, vinyl triethoxysilane 3 parts, isopropyl alcohol 160 parts, silicon carbide@carbon shell / reduced graphene oxide composite powder filler 10 parts, hydrochloric acid 0.5 parts, polysilicate 28 parts.

[0054] The silicon carbide@carbon shell / reduced graphene oxide composite powder filler is made of the following components by weight: nano silicon carbide 8 parts, polyethyleneimine 3 parts, 3-aminopropyl triethoxysilane 4 parts, graphene oxide 2 parts.

[0055] The preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler specifically includes the following steps:

[0056] (1) 0.8 g of nano silicon carbide is added to a round-bottom flask containing 50 mL of anhydrous ethanol, and ultrasonic oscillation is performed for 30 min to obtain a nano silicon carbide dispersion liquid for later use. Meanwhile, polyethyleneimine with a molecular weight of 3500 is dissolved in 20 mL of an ethanol solution with a mass fraction of 95% and adjusted to a pH of 4.0 using acetic acid. The addition amount of polyethyleneimine is 0.3 g. The polyethyleneimine provides an amino active site, can strengthen the internal interface bonding of the filler, and plays an active role as a molecular bridge between materials. Then, 2 drops per second of the nano silicon carbide dispersion liquid is added. After the dropwise addition is completed, the round-bottom flask is immersed in a constant-temperature water bath at 40°C, and the reaction is performed under magnetic stirring for 12 h. After centrifugal separation, the supernatant is removed, and then the ethanol solution is supplemented to 70 mL. Ultrasonic oscillation is performed for 3 min, followed by centrifugal separation. This process is repeated three times. Finally, the precipitate is dried in a vacuum drying oven at 60°C. The polyethyleneimine forms an organic coating layer on the surface of the nano silicon carbide and produces a steric hindrance effect, reducing the agglomeration between the nano silicon carbide particles, so that they can be uniformly dispersed in the coating matrix, thereby effectively filling the pores in the coating curing and better playing the high-temperature resistance and corrosion resistance of silicon carbide itself, to obtain polyethyleneimine modified silicon carbide;

[0057] (2) The polyethyleneimine modified silicon carbide of step (1) is dispersed in 80 mL of 75% ethanol solution, and ultrasonic dispersion treatment is performed for 0.5 h to obtain a dispersion liquid for use, 3-aminopropyl triethoxysilane is added to 50 mL of anhydrous ethanol, and the amount of 3-aminopropyl triethoxysilane added is 0.4 mL, the other end of 3-aminopropyl triethoxysilane is an amino group, which further increases the amino group density and reactivity of the particle surface, and is conducive to the grafting efficiency and strength with graphene oxide in the subsequent process, and glacial acetic acid is used to adjust the pH to 3.0 to obtain a hydrolysis liquid for use, then the dispersion liquid is slowly added to the hydrolysis liquid under stirring at a speed of 300 rpm, stirring is performed for 0.5 h, and then reaction is performed in a constant temperature water bath at 65°C for 3 h, centrifugation is performed, the precipitate is redispersed in an ethanol solution and centrifuged twice, the precipitate after washing is dried in a vacuum drying oven at 60°C, the silanol groups after hydrolysis of 3-aminopropyl triethoxysilane can not only form a firm and heat-resistant Si-O-Si covalent bond with the hydroxyl groups on the surface of the silicon carbide particles, but also stabilize the precursor structure, fix the polyethyleneimine on the surface of the silicon carbide, and ensure the durability of the entire core-shell structure in a high-temperature environment, at the same time, the intervention of 3-aminopropyl triethoxysilane not only reduces the problem of filler original agglomeration caused by entanglement and adhesion of the polyethyleneimine chain segment in the processing process, so that it fully penetrates and fills into the nanoscale micropores formed by the polymer molecular chain, but also greatly increases the surface amino group density and uniformity on the polyethyleneimine layer which is already rich in amino groups, which is conducive to optimizing the interface bonding between fillers and between fillers and the matrix, and this stronger interface interaction helps to prevent the agglomeration and sedimentation of fillers during paint storage and curing, reduces the occurrence of micropore defects, and obtains silanized polyethyleneimine modified silicon carbide;

[0058] (3) 0.1 g of the silanized polyethyleneimine modified silicon carbide from step (2) is weighed into 200 mL N,N-dimethylacetamide solvent, and ultrasonic dispersion is performed for 20 min to obtain a silanized polyethyleneimine modified silicon carbide dispersion liquid, which is used as received. Graphene oxide is dispersed in 200 mL N,N-dimethylacetamide solvent, and the amount of graphene oxide added is 0.2 g. Graphene oxide has good thermal stability, and its two-dimensional sheet structure not only extends and zigzags the penetration path of the corrosive medium, but also overlaps, covers, and blocks the micro pores or defects, thereby improving the micro pores in the coating. Ultrasonic dispersion is performed for 30 min, then 0.2 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 0.10 g of N-hydroxysuccinimide are added, and stirring is performed at room temperature for 1 h to obtain an activated suspension, which is used as received. Then the activated suspension is added to the silanized polyethyleneimine modified silicon carbide dispersion liquid, and transferred to a 100°C oil bath for constant temperature stirring for 3 h. Finally, centrifugation is performed, the precipitate is washed twice with anhydrous ethanol, vacuum dried, ground, and the like. After activation of the graphene oxide, the carboxyl groups on the surface form amide bonds with the amino groups of the silanized polyethyleneimine modified silicon carbide, and the two together construct a stable heat-resistant network, enhancing the integrity of the heat-resistant barrier of the coating, preventing the coating from flowing, bubbling, or large-area cracking, and thereby improving the high-temperature resistance of the coating. Moreover, this stable covalent bond eliminates the risk of weak interfacial bonding, so that the corrosive medium cannot penetrate from the interface between the two, and the synergistic effect of the nanoscale particles and the micrometer-scale sheets achieves all-around, dead-angle-free filling from the nanometer to the micrometer scale, thereby reducing the occurrence of micro-pore defects and improving the corrosion resistance. A composite powder is obtained.

[0059] (4) The composite powder from step (3) is placed in a tube furnace, and heated to 300°C at a rate of 2°C / min under an argon atmosphere, and held for 1 h. In this process, the graphene oxide is converted to reduced graphene oxide, and the thermal stability and chemical stability are further improved. At the same time, the polyethyleneimine and 3-aminopropyltriethoxysilane undergo pyrolysis and form an amorphous carbon shell at the interface between the silicon carbide and the reduced graphene oxide, more firmly connecting the silicon carbide particles and the reduced graphene oxide sheets together, and the amorphous carbon shell formed is more resistant to high temperatures and corrosion than the amide bond alone. Moreover, the dense carbon shell further eliminates the micro defects at the interface, making the penetration path of the corrosive medium more tortuous and difficult, and also providing complete and stable skeletal support at high temperatures. A silicon carbide@carbon shell / reduced graphene oxide composite powder filler is obtained.

[0060] The present embodiment provides a preparation method of a high-temperature-resistant steel pipe anticorrosive coating, specifically including the following steps:

[0061] S1, 10.0 g of sodium fluorosilicate, 20.0 g of 3-mercaptopropyl triethoxysilane, and 3.0 g of vinyl triethoxysilane are added to 160.0 g of isopropyl alcohol, and a high-speed shearing disperser is used to stir for 20 min at a speed of 600 rpm, 10.0 g of silicon carbide@carbon shell / reduced graphene oxide composite powder filler is added at a speed of 1000 rpm, the speed is adjusted to 8000 rpm, and mixed for 20 min, then 5.0 g of 10% mass fraction hydrochloric acid aqueous solution is added, the reaction temperature is controlled at 35℃, 100 mL of polysilicate pre-hydrolysate containing 28.0 g of polysilicate is slowly added within 5 h under stirring at a speed of 600 rpm, the polysilicate is a precursor for forming an inorganic silica network, and the silica network formed after curing is an inorganic glassy structure with a very high melting point, which improves the high temperature resistance of the coating, at the same time, the silica network not only has excellent resistance to most acids, solvents and chemical media, but also reduces the penetration of corrosive media through its low permeability structure, providing stronger corrosion resistance, the viscosity of the system is monitored and adjusted to 1000 mPa·s during the period, and after complete addition, the stirring reaction is continued for 1 h, in the insulating silica sol matrix, the silicon carbide@carbon shell / reduced graphene oxide composite powder filler acts as a reinforcing body, and a highly cross-linked and dense organic-inorganic hybrid composite network structure is formed through silane chemical cross-linking, a dense physical and chemical barrier is constructed, excellent high temperature resistance and corrosion resistance are presented, and the re-agglomeration of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler is effectively prevented, eliminating the interface micropores and defects caused by agglomeration during coating curing, and obtaining a reinforcing body modified silica sol;

[0062] S2, the reinforcing body modified silica sol, titanium dioxide, mica powder, BYK-323 leveling agent, and FLOWLENAC-300 defoaming agent described in step S1 are ball milled using a horizontal ball mill, wherein the ball-to-material ratio is 2:1, the ball milling time is 4 h, and the material temperature is controlled at 34℃, ensuring that the particle size is not more than 20 μm, the reinforcing body modified silica sol acts as a continuous matrix of the coating, providing film forming property, adhesion, high temperature resistance, and physical and chemical protection, and the other fillers and additives are dispersed therein, synergistically enhancing the protective performance and workability, so that the coating simultaneously has the high temperature resistance and corrosion resistance of inorganic materials and the flexibility and strong adhesion of organic materials, and is particularly suitable for steel pipe protection in harsh environments such as high temperature and corrosion, and a high temperature resistant steel pipe anti-corrosion coating is obtained.

[0063] Example 4

[0064] The present embodiment proposes a high temperature resistant steel pipe anti-corrosion coating, which comprises the following components by weight: 100 parts of reinforcing body modified silica sol, 25 parts of titanium dioxide, 15 parts of mica powder, 0.4 parts of BYK-323 leveling agent, and 0.8 parts of FLOWLENAC-300 defoaming agent.

[0065] The reinforcing body modified silica sol is made of the following components by weight: sodium fluorosilicate 15 parts, 3-mercaptopropyl triethoxysilane 20 parts, vinyl triethoxysilane 3 parts, isopropyl alcohol 180 parts, silicon carbide@carbon shell / reduced graphene oxide composite powder filler 15 parts, hydrochloric acid 0.7 parts, polysilicate 28 parts.

[0066] The silicon carbide@carbon shell / reduced graphene oxide composite powder filler is made of the following components by weight: nano silicon carbide 10 parts, polyethyleneimine 3 parts, 3-aminopropyl triethoxysilane 4 parts, graphene oxide 3 parts.

[0067] The preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler specifically includes the following steps:

[0068] (1) 1.0 g of nano silicon carbide is added to a round-bottom flask containing 50 mL of anhydrous ethanol, and ultrasonic oscillation is performed for 30 min to obtain a nano silicon carbide dispersion liquid for later use. Meanwhile, polyethyleneimine with a molecular weight of 7500 is dissolved in 20 mL of an ethanol solution with a mass fraction of 95% and adjusted to a pH of 5.0 using acetic acid. The addition amount of polyethyleneimine is 0.3 g. The polyethyleneimine provides an amino active site, which can strengthen the internal interface bonding of the filler and play a positive role as a molecular bridge between materials. Then, 1 drop / second of the nano silicon carbide dispersion liquid is added thereto. After the dropwise addition is completed, the round-bottom flask is immersed in a constant-temperature water bath at 45°C, and the reaction is performed under magnetic stirring for 12 h. After centrifugal separation, the supernatant is removed, and then the ethanol solution is supplemented to 70 mL again. Ultrasonic oscillation is performed for 3 min, followed by centrifugal separation. This process is repeated 5 times. Finally, the precipitate is dried in a vacuum drying oven at 80°C. The polyethyleneimine forms an organic coating layer on the surface of the nano silicon carbide and produces a steric hindrance effect, reducing the agglomeration between the nano silicon carbide particles, so that they can be uniformly dispersed in the coating matrix, thereby effectively filling the pores in the coating curing and better playing the high-temperature resistance and corrosion resistance of silicon carbide itself, to obtain polyethyleneimine modified silicon carbide;

[0069] (2) The polyethyleneimine modified silicon carbide of step (1) is dispersed in 100 mL of 75% ethanol solution, and ultrasonic dispersion treatment is performed for 0.5 h to obtain a dispersion liquid for use, 3-aminopropyl triethoxysilane is added to 50 mL of anhydrous ethanol, and the amount of 3-aminopropyl triethoxysilane added is 0.4 mL, the other end of 3-aminopropyl triethoxysilane is an amino group, which further increases the amino group density and reactivity of the particle surface, and is conducive to the grafting efficiency and strength with graphene oxide in the subsequent process, and glacial acetic acid is used to adjust the pH to 4.0 to obtain a hydrolysis liquid for use, then the dispersion liquid is slowly added to the hydrolysis liquid under stirring at a speed of 500 rpm, stirring is performed for 0.5 h, and then reaction is performed in a constant temperature water bath at 75°C for 3 h, centrifugation is performed, the precipitate is redispersed in an ethanol solution and centrifuged for 3 times, the precipitate after washing is dried in a vacuum drying oven at 80°C, the silanol groups after hydrolysis of 3-aminopropyl triethoxysilane can not only form a firm and heat-resistant Si-O-Si covalent bond with the hydroxyl groups on the surface of the silicon carbide particles, but also stabilize the precursor structure, fix the polyethyleneimine on the surface of the silicon carbide, and ensure the durability of the entire core-shell structure in a high-temperature environment, at the same time, the intervention of 3-aminopropyl triethoxysilane not only reduces the problem of filler original agglomeration caused by entanglement and adhesion of the polyethyleneimine chain segment in the processing process, so that it fully penetrates and fills into the nanoscale small pores formed by the polymer molecular chain, but also greatly increases the surface amino group density and uniformity on the polyethyleneimine layer which is already rich in amino groups, which is conducive to optimizing the interface bonding between fillers and between fillers and the matrix, and this stronger interface interaction helps to prevent the agglomeration and sedimentation of fillers during paint storage and curing, reduces the occurrence of micropore defects, and obtains silanized polyethyleneimine modified silicon carbide;

[0070] (3) 0.3 g of the silanized polyethyleneimine modified silicon carbide in step (2) is weighed into 200 mL of N,N-dimethylacetamide solvent, and ultrasonic dispersion is performed for 20 min to obtain a silanized polyethyleneimine modified silicon carbide dispersion liquid, which is used as received. Graphene oxide is dispersed in 200 mL of N,N-dimethylacetamide solvent, and the amount of graphene oxide added is 0.3 g. The graphene oxide has good thermal stability, and its two-dimensional sheet structure not only extends and zigzags the penetration path of the corrosion medium, but also overlaps, covers, and blocks the micro pores or defects, thereby improving the micro pores in the coating. Ultrasonic dispersion is performed for 30 min, then 0.3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 0.18 g of N-hydroxysuccinimide are added, and stirring is performed at room temperature for 1 h to obtain an activated suspension, which is used as received. Then, the activated suspension is added to the silanized polyethyleneimine modified silicon carbide dispersion liquid, and transferred to an oil bath at 105°C, and constant temperature stirring is performed for 3 h. Finally, centrifugation is performed, the precipitate is washed with anhydrous ethanol for 3 times, vacuum dried, ground, and the like. After the graphene oxide is activated, the carboxyl groups on the surface form amide bonds with the amino groups of the silanized polyethyleneimine modified silicon carbide, and the two together construct a stable heat-resistant network, which enhances the integrity of the heat-resistant barrier of the coating, prevents the coating from flowing, bubbling, or large-area cracking, and further improves the high-temperature resistance of the coating. In addition, this stable covalent bond eliminates the risk of weak interfacial bonding, so that the corrosion medium cannot penetrate from the interface between the two, and the synergistic effect of the nanoscale particles and the micrometer-scale sheets realizes all-around, dead-angle-free filling from the nanometer to the micrometer scale, thereby reducing the occurrence of micro-pore defects and improving the corrosion resistance. A composite powder is obtained.

[0071] (4) The composite powder in step (3) is placed in a tube furnace, and heated to 400°C at a rate of 5°C / min under the protection of an argon atmosphere, and held for 1 h. In this process, the graphene oxide is converted into reduced graphene oxide, and the thermal stability and chemical stability of the reduced graphene oxide are further improved. At the same time, the polyethyleneimine and 3-aminopropyltriethoxysilane pyrolyze and form an amorphous carbon shell at the interface between the silicon carbide particles and the reduced graphene oxide sheets, which more firmly connects the silicon carbide particles and the reduced graphene oxide sheets together, and is more resistant to high temperature and corrosion than the amide bond alone. In addition, the dense carbon shell further eliminates the micro defects at the interface, making the penetration path of the corrosion medium more tortuous and difficult, and also providing a complete and stable skeleton support at high temperatures. A silicon carbide@carbon shell / reduced graphene oxide composite powder filler is obtained.

[0072] The embodiment provides a preparation method of a high-temperature-resistant steel pipe anticorrosive coating, and specifically includes the following steps:

[0073] S1, 15.0 g of sodium fluorosilicate, 20.0 g of 3-mercaptopropyl triethoxysilane, 3.0 g of vinyl triethoxysilane are added to 180.0 g of isopropyl alcohol, and stirred at a speed of 800 rpm for 20 min using a high-speed shearing disperser, 15.0 g of silicon carbide@carbon shell / reduced graphene oxide composite powder filler is added at a speed of 2000 rpm, the speed is adjusted to 12000 rpm, and mixed for 20 min, then 7.0 g of 10% mass fraction hydrochloric acid aqueous solution is added, the reaction temperature is controlled at 40℃, 100 mL of polysilicate pre-hydrolysate containing 28.0 g of polysilicate is slowly added at a stirring speed of 800 rpm within 5 h, the polysilicate is the precursor of the inorganic silica network, and the silica network formed after curing is an inorganic glassy structure with extremely high melting point, which improves the high temperature resistance of the coating. At the same time, the silica network not only has excellent resistance to most acids, solvents and chemical media, but also reduces the penetration of corrosive media through its low permeability structure, providing stronger corrosion resistance. The viscosity of the system is monitored and adjusted to 1500 mPa·s during the period. After complete addition, continue to stir for 1 h. In the insulating silica sol matrix, the silicon carbide@carbon shell / reduced graphene oxide composite powder filler acts as a reinforcing body, and a highly cross-linked and dense organic-inorganic hybrid composite network structure is formed through silane chemical cross-linking, which builds a dense physical and chemical barrier, showing excellent high temperature resistance, corrosion resistance, and can effectively prevent the re-agglomeration of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler, eliminating the interface micropores and defects generated during the curing of the coating. Reinforced silica sol is obtained;

[0074] S2, the reinforced silica sol, titanium dioxide, mica powder, BYK-323 leveling agent and FLOWLENAC-300 defoaming agent described in step S1 are treated by horizontal ball milling, wherein the ball-to-material ratio is 3:1, the ball milling time is 4 h, and the material temperature is controlled at 38℃ to ensure that the particle size is not more than 20 μm. The reinforced silica sol acts as a continuous matrix of the coating, providing film forming property, adhesion, high temperature resistance and physical and chemical protection, and the other fillers and additives are dispersed therein, which synergistically enhances the protective performance and workability, so that the coating has both the high temperature resistance and corrosion resistance of inorganic materials and the flexibility and strong adhesion of organic materials. It is especially suitable for steel pipe protection in harsh environments such as high temperature and corrosion, and a high temperature resistant steel pipe anticorrosion coating is obtained.

[0075] Comparative Example 1

[0076] The comparative example provides a high-temperature-resistant steel pipe anticorrosive coating, which is different from example 1 in that the silicon carbide@carbon shell / reduced graphene oxide composite powder filler does not contain graphene oxide; the preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler does not include step (3); and the preparation method of the high-temperature-resistant steel pipe anticorrosive coating is the same as that of example 1.

[0077] Comparative example 2

[0078] The comparative example provides a high-temperature-resistant steel pipe anticorrosive coating, which is different from example 1 in that the silicon carbide@carbon shell / reduced graphene oxide composite powder filler does not contain 3-aminopropyl triethoxysilane, and is not subjected to pyrolysis in a tube furnace; the preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler does not include steps (2) and (4); and the preparation method of the high-temperature-resistant steel pipe anticorrosive coating is the same as that of example 1.

[0079] Comparative example 3

[0080] The comparative example provides a high-temperature-resistant steel pipe anticorrosive coating, which is different from example 1 in that the reinforcing body modified silica sol does not contain 3-mercaptopropyl triethoxysilane and vinyl triethoxysilane; the preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler is the same as that of example 1; and the preparation method of the high-temperature-resistant steel pipe anticorrosive coating does not add 3-mercaptopropyl triethoxysilane and vinyl triethoxysilane in step S1.

[0081] Experimental example 1

[0082] High-temperature resistance experiment

[0083] Test sample: the high-temperature-resistant steel pipe anticorrosive coatings prepared in examples 1-4 and comparative examples 1-3.

[0084] Test method: the test sample is sprayed on a 440C martensitic stainless steel substrate, and after heat curing at 180°C (coating thickness is 80±10 μm), the high-temperature resistance experiment is carried out according to the basic principles of GB / T1735-2009, the coating sample is placed in a muffle furnace, and the limit heat resistance temperature of the coating is determined by continuously dynamic heating (5°C / min), and the temperature at which the first crack and falling phenomenon appears is recorded as the high-temperature limit (°C).

[0085] Figure 1The high temperature limit results of Examples 1-4 and Comparative Examples 1-3 are shown in the figure; as shown in the figure, the high temperature limit of Examples 1-4 is 585-650℃, indicating good high temperature resistance; the high temperature limit of Comparative Examples 1-3 is 400-500℃, indicating general or poor high temperature resistance; the silicon carbide@carbon shell / reduced graphene oxide composite powder filler in Comparative Example 1 does not contain graphene oxide, and cannot form a stable reduced graphene oxide skeleton through thermal reduction, which is not conducive to providing a heat-resistant and heat-insulating physical barrier in the coating, resulting in general high temperature resistance; the silicon carbide@carbon shell / reduced graphene oxide composite powder filler in Comparative Example 2 does not contain 3-aminopropyl triethoxysilane and is not subjected to pyrolysis in a tube furnace, which is not conducive to forming a high-temperature-resistant amorphous carbon shell layer, firmly connecting the silicon carbide particles and the graphene oxide layers, and fixing the polyethyleneimine on the surface of the silicon carbide and the strength of the graphene oxide, and cannot provide complete and stable skeleton support at high temperature, resulting in poor high temperature resistance; the reinforcing agent modified silica sol in Comparative Example 3 does not contain 3-mercaptopropyl triethoxysilane and vinyl triethoxysilane, which cannot react with polysilicate to form a high-temperature-resistant and highly cross-linked Si-O-Si three-dimensional network structure, and cannot enhance the interfacial bonding force between the silicon carbide@carbon shell / reduced graphene oxide composite powder filler and the silica sol through flexible molecular chains, which is not conducive to reducing the interfacial micropores and defects, destroying the integrity of the coating, and resulting in poor high temperature resistance.

[0086] Experimental Example 2

[0087] Corrosion resistance experiment

[0088] Test sample: the high-temperature-resistant steel pipe anticorrosive coating prepared in Examples 1-4 and Comparative Examples 1-3.

[0089] Test method: the test sample is sprayed on the 440C martensitic stainless steel substrate and drawn X-shaped to the substrate, and after 180℃ heat curing (coating thickness is 80±10μm), it is placed in a salt spray chamber, the temperature is 35±2℃, the salt spray solution deposition amount is 1.5±0.5mL / h, a 5% NaCl solution (pH value is 6.5-7.2) is used, and the salt spray resistance test is carried out according to the national standard GB / T1771-2007 for 500h, after the test is completed, the rust is peeled off along the X-shaped scratch, the length of the maximum corrosion of the substrate is measured, and the maximum corrosion length (mm) is recorded. The smaller the maximum corrosion length, the stronger the corrosion resistance.

[0090] Figure 2The corrosion maximum length results of Examples 1-4 and Comparative Examples 1-3 are shown in the figure; as shown, the corrosion maximum length of Examples 1-4 is 0.2-0.6 mm, indicating strong corrosion resistance; the corrosion maximum length of Comparative Examples 1-3 is 1.5-4.2 mm, indicating general or weak corrosion resistance; Comparative Example 1 does not contain graphene oxide in the silicon carbide@carbon shell / reduced graphene oxide composite powder filler, cannot bend the penetration path of the corrosive medium through the two-dimensional sheet structure, and cannot improve the micropores in the coating by lapping, covering and plugging in the micropores or defects, thereby being not conducive to optimizing the corrosion barrier, resulting in general corrosion resistance; Comparative Example 2 does not contain 3-aminopropyl triethoxysilane and is not subjected to pyrolysis in a tube furnace, cannot form a dense corrosion-resistant carbon shell, is not conducive to eliminating the micropores at the interface, increasing the penetration weak point of the corrosive medium, and is not conducive to stably connecting the silicon carbide particles and graphene oxide sheets, resulting in weak corrosion resistance; Comparative Example 3 does not contain 3-mercaptopropyl triethoxysilane and vinyl triethoxysilane in the reinforcing body modified silica sol, which is not conducive to improving the cohesive strength and crosslinking density of the silica sol, weakening the corrosion protection of the barrier, and is not conducive to seamlessly embedding the silicon carbide@carbon shell / reduced graphene oxide composite powder filler in the silica sol, increasing the interface micropores and defects, destroying the density of the coating, and resulting in weak corrosion resistance.

[0091] The above experimental results show that the high temperature resistance and corrosion resistance of Examples 1-4 of the present application are significantly better than those of Comparative Examples 1-3, wherein the high temperature resistance and corrosion resistance of Example 1 using the silicon carbide@carbon shell / reduced graphene oxide composite powder filler and the reinforcing body modified silica sol are better, the silicon carbide@carbon shell / reduced graphene oxide composite powder filler is used as a reinforcing body and is embedded in the silica sol by crosslinking, forming a reinforcing body modified silica sol, and presenting a highly crosslinked and dense organic-inorganic hybrid composite network structure, which plays a core role as a continuous matrix of the coating, not only improving the high temperature resistance and corrosion resistance of the coating, but also enhancing the interfacial bonding force between the components, effectively preventing the filler from agglomerating and settling during storage and curing, reducing the occurrence of micropore defects, and further enhancing the effectiveness and long-term effectiveness of the high temperature resistant and corrosion resistant coating protection.

[0092] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application.

[0093] The above describes the present application and its embodiments, which are not limited, and the drawings only show one of the embodiments of the present application, and the actual application is not limited thereto. In general, if a person skilled in the art is inspired by it, without departing from the purpose of the present application, without creative design, similar ways and embodiments of the technical solution should belong to the protection scope of the present application.

Claims

1. A high temperature resistant steel pipe anticorrosive coating characterized by: The high-temperature-resistant steel pipe anticorrosive coating comprises the following components in parts by weight: 90-100 parts of reinforced modified silica sol, 15-25 parts of titanium white, 10-15 parts of mica powder, 0.2-0.4 parts of BYK-323 leveling agent, and 0.4-0.8 parts of FLOWLENAC-300 defoaming agent; the reinforced modified silica sol is prepared from the following components in parts by weight: 10-15 parts of sodium fluorosilicate, 20-25 parts of 3-mercaptopropyl triethoxysilane, 3-5 parts of vinyl triethoxysilane, 160-180 parts of isopropyl alcohol, 10-15 parts of silicon carbide@carbon shell / reduced graphene oxide composite powder filler, 0.5-0.7 parts of hydrochloric acid, and 28-32 parts of polysilicate; the silicon carbide@carbon shell / reduced graphene oxide composite powder filler is prepared from the following components in parts by weight: 8-10 parts of nano silicon carbide, 3-5 parts of polyethyleneimine, 4-5 parts of 3-aminopropyl triethoxysilane, and 2-3 parts of graphene oxide.

2. A method of preparing a corrosion protective coating for a high-temperature-resistant steel pipe according to claim 1, characterized by: Specifically comprising the following steps: S1, 10.0-15.0g of sodium fluorosilicate, 20.0-25.0g of 3-mercaptopropyl triethoxysilane, and 3.0-5.0g of vinyl triethoxysilane are added to 160.0-180.0g of isopropyl alcohol, and a high-speed shearing disperser is used to stir at a speed of 600-800rpm for 20-30min; 10.0-15.0g of silicon carbide@carbon shell / reduced graphene oxide composite powder filler is added at a speed of 1000-2000rpm, the speed is adjusted to 8000-12000rpm, and mixing is performed for 20-40min; then 5.0-7.0g of 10% hydrochloric acid aqueous solution is added, the reaction temperature is controlled at 35-40℃, 100mL of polysilicate pre-hydrolyzate is slowly added under stirring at a speed of 600-800rpm within 5h, the viscosity of the system is monitored and adjusted to 1000-1500mPa·s during the period, and after complete addition, stirring is continued for 1-2h to obtain reinforced modified silica sol; S2, the reinforced modified silica sol, titanium white, mica powder, BYK-323 leveling agent, and FLOWLENAC-300 defoaming agent obtained in step S1 are subjected to ball milling treatment by using a horizontal ball mill, wherein the ball-to-material ratio is 2-3:1, the ball milling time is 4-8h, and the material temperature is controlled at 34-38℃ to ensure that the particle fineness is not more than 20μm, thereby obtaining the high-temperature-resistant steel pipe anticorrosive coating.

3. The method of claim 2, wherein the method further comprises: In step S1, the polysilicate pre-hydrolyzate contains 28.0-32.0g of polysilicate. ​ 4. The method of claim 3, wherein the method is characterized by: The preparation method of the silicon carbide@carbon shell / reduced graphene oxide composite powder filler specifically comprises the following steps: (1) 0.8-1.0 g of nano silicon carbide is added to a round-bottom flask containing 50 mL of anhydrous ethanol, and ultrasonic oscillation is performed for 30-40 min to obtain a nano silicon carbide dispersion liquid for use, while polyethyleneimine with a molecular weight of 3500-7500 is dissolved in 20 mL of a 95% ethanol solution and adjusted to a pH of 4.0-5.0 using acetic acid, then 1-2 drops of the nano silicon carbide dispersion liquid is added per second, after the dropwise addition is completed, the round-bottom flask is immersed in a constant-temperature water bath at 40-45°C, and the reaction is performed under magnetic stirring for 12-24 h, centrifugal separation is performed, the supernatant is removed, and then the ethanol solution is supplemented to 70 mL, ultrasonic oscillation is performed for 3-5 min, then centrifugal separation is performed, and this process is repeated 3-5 times, finally the precipitate is dried in a vacuum drying oven at 60-80°C to obtain polyethyleneimine-modified silicon carbide; (2) The polyethyleneimine-modified silicon carbide described in step (1) is dispersed in 80-100 mL of a 75% ethanol solution, ultrasonic dispersion treatment is performed for 0.5-1 h to obtain a dispersion liquid for use, 3-aminopropyltriethoxysilane is added to 50 mL of anhydrous ethanol and adjusted to a pH of 3.0-4.0 using glacial acetic acid to obtain a hydrolysis liquid for use, then the dispersion liquid is slowly added to the hydrolysis liquid under stirring at a speed of 300-500 rpm, stirring is performed for 0.5-1 h, then the reaction is performed in a constant-temperature water bath at 65-75°C for 3-4 h, centrifugal separation is performed, the precipitate is redispersed in an ethanol solution and centrifugally separated for 2-3 times, and the washed precipitate is dried in a vacuum drying oven at 60-80°C to obtain silanized polyethyleneimine-modified silicon carbide; (3) 0.1-0.3 g of the silanized polyethyleneimine-modified silicon carbide described in step (2) is added to 200 mL of N,N-dimethylacetamide solvent, ultrasonic dispersion is performed for 20-30 min to obtain a silanized polyethyleneimine-modified silicon carbide dispersion liquid for use, graphene oxide is dispersed in 200 mL of N,N-dimethylacetamide solvent, ultrasonic dispersion is performed for 30-40 min, then 0.2-0.3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 0.10-0.18 g of N-hydroxysuccinimide are added, stirring is performed at room temperature for 1-2 h to obtain an activated suspension for use, then the activated suspension is added to the silanized polyethyleneimine-modified silicon carbide dispersion liquid, transferred to an oil bath at 100-105°C, and constant-temperature stirring is performed for 3-4 h, finally centrifugal separation is performed, the precipitate is washed with anhydrous ethanol for 2-3 times, vacuum dried, and ground to obtain a composite powder; (4) The composite powder described in step (3) is placed in a tube furnace, heated to 300-400°C at a rate of 2-5°C / min under the protection of an argon atmosphere, and held for 1-2 h to obtain a silicon carbide@carbon shell / reduced graphene oxide composite powder filler.

5. The method of claim 4, wherein the method is characterized by: In step (1), the amount of polyethyleneimine added is 0.3-0.5 g.

6. The method of claim 5, wherein the method is characterized by: In step (2), the amount of 3-aminopropyltriethoxysilane added is 0.4-0.5 mL.

7. The method of claim 6, wherein the method further comprises the step of: In step (3), the amount of graphene oxide added is 0.2-0.3 g. ​

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