A high-temperature resistant and oxidation-resistant metal protective coating composite material and its preparation method

Abstract

This invention relates to the field of coating technology, and more particularly to a high-temperature resistant and antioxidant metal protective coating composite material and its preparation method, comprising the following steps: copolymerizing vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate to synthesize a terpolymer; next, dissolving the terpolymer in N-methylpyrrolidone to prepare a coating solution, and coating the coating solution onto the surface of a pretreated metal substrate to form a uniform wet film; finally, subjecting the wet film to photocrosslinking curing and thermal crosslinking curing treatments sequentially. This invention, through the synergistic effect of vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate, combined with a reasonable preparation process, produces a high-temperature resistant and antioxidant metal protective coating composite material with excellent coating adhesion, high-temperature stability, and antioxidant properties.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a high-temperature resistant and oxidation-resistant metal protective coating composite material and its preparation method. Background Technology

[0002] Hot-end components in fields such as chemical pipelines, automotive exhaust systems, and electronic packaging serve as core load-bearing units for equipment operation. They operate for extended periods in oxygen-containing environments at 100-200°C. In some scenarios, they are also subject to corrosion from moisture and trace corrosive impurities, such as acid and alkali vapors in chemical pipelines, nitrogen oxides in automotive exhaust, and trace amounts of moisture in electronic packaging environments. These operating conditions are extremely harsh. The metal substrates of these components are mostly made of materials such as carbon steel, various types of stainless steel, and aluminum alloys. While each of these substrates has its advantages—carbon steel is inexpensive and has moderate strength, stainless steel has basic corrosion resistance, and aluminum alloys are lightweight and have excellent thermal conductivity—in the aforementioned complex operating environments, a natural oxide film will spontaneously form on their surfaces, making long-term protection difficult.

[0003] However, this natural oxide film structure is generally loose and porous, with numerous micropores and cracks throughout the film layer. These defects become channels for corrosive media such as oxygen and water vapor to diffuse into the substrate, failing to form an effective protective barrier. Furthermore, the natural oxide film is relatively thin and has weak adhesion to the metal substrate, making it prone to detachment and cracking under long-term temperature fluctuations, slight vibrations, and media erosion, thus losing its protective function. With increasing service life, corrosive media continue to penetrate to the metal substrate surface, triggering a series of failure problems, specifically manifested as discoloration of the substrate surface. To achieve long-term stable service for hot-end components, the industry commonly employs surface modification technology, using mature processes such as spraying, dipping, and electrodeposition to construct a composite coating structure on the metal substrate surface. Various composite coating systems can effectively improve the interface density and coating adhesion of hot-end components, extending their service life. Among them, organic-inorganic hybrid coatings combine flexibility with temperature and corrosion resistance, making them suitable for chemical pipelines, electronic packaging, and other scenarios; nanofiller-reinforced epoxy resin coatings offer superior density and corrosion resistance, making them suitable for scenarios with more complex corrosion; and thin-layer metal / ceramic composite coatings provide outstanding protection, making them suitable for hot-end components with extremely high protection requirements.

[0004] In existing technologies, the adhesion between resin coatings and metal substrates (carbon steel, stainless steel, aluminum alloys) is relatively weak, and the difference in their coefficients of thermal expansion is significant. This makes them prone to internal stress during temperature fluctuations, leading to coating cracking, peeling, and loss of protective function. Furthermore, while resin coatings can block basic moisture and oxygen penetration, they are susceptible to swelling and degradation when exposed to acid and alkali vapors in chemical pipelines or corrosive impurities in automotive exhaust. After long-term service, they are prone to developing pores and cracks, failing to provide sustained protection against corrosive media. Simultaneously, the resin itself has low hardness and poor wear resistance; even slight vibrations and friction during the service of hot-end components can easily scratch and damage the coating, exposing the metal substrate to a corrosive environment and accelerating component failure. Summary of the Invention

[0005] To address the problems mentioned in the background section, this invention provides a high-temperature resistant and oxidation-resistant metal protective coating composite material and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a high-temperature resistant and oxidation-resistant metal protective coating composite material includes the following steps:

[0008] S1. Vinyltriethoxysilane, 4-acryloyloxybenzophenone and lanthanum acrylate are copolymerized. The mixture is stirred continuously at a speed of 200-300 r / min to obtain a terpolymer.

[0009] S2. Add the terpolymer to N-methylpyrrolidone to obtain a coating solution. During the preparation of the coating solution, stir and dissolve at room temperature of 25-30°C for 30-60 minutes to ensure that the terpolymer is completely dissolved and there are no obvious particles. Apply the coating solution to the surface of the pretreated metal substrate to form a wet film.

[0010] S3. The wet film is subjected to photocrosslinking curing and thermal crosslinking curing in sequence to obtain a high-temperature resistant and antioxidant metal protective coating composite material.

[0011] Furthermore, the lanthanum acrylate in step S1 is obtained through the following steps:

[0012] Lanthanum oxide was calcined at 600-700℃ for 1-4 hours to obtain activated lanthanum oxide. The calcination process was carried out in a muffle furnace at a heating rate of 5℃ / min. After calcination, the mixture was allowed to cool naturally to room temperature. The activated lanthanum oxide was then mixed with acrylic acid at a molar ratio of 1:(1-1.2). Deionized water or an alcohol-water mixture was added, with a volume ratio of alcohol to water of (1-3):1. The amount of solvent used was 8-12 times the mass of the activated lanthanum oxide. The mixture was stirred at 50-70℃ for 2-8 hours at a stirring rate of 150-250 r / min to obtain a reaction solution. The reaction solution was then distilled under reduced pressure at a vacuum of 0.08-0.10 MPa and a distillation temperature of 60-80℃ to obtain a crude product. The crude product was washed 2-3 times with anhydrous ethanol, each time using 3-5 times the mass of the crude product. The product was then dried at 80-100℃ for 4-6 hours to obtain lanthanum acrylate.

[0013] Further, in step S1, the mass ratio of vinyltriethoxysilane, 4-acryloyloxybenzophenone and lanthanum acrylate is (12.8-18.9):(1.4-4.2):(1.1-3.0), preferably (14.5-16.8):(2.2-3.5):(1.8-2.5).

[0014] Furthermore, the copolymerization reaction in step S1 also includes an initiator and a solvent. The initiator is selected from azobisisobutyronitrile (AIBN), and the amount of initiator used is 0.1-0.3% of the total mass of vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate. Preferably, the amount of initiator used is 0.15-0.25% of the total mass. The AIBN is purified by recrystallization before use. The solvent is selected from one of tetrahydrofuran, N-methylpyrrolidone, dioxane, or ethyl acetate. Preferably, the solvent is tetrahydrofuran or N-methylpyrrolidone. The ratio of the solvent to the total mass of vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate is (5-10) mL:1 g, and preferably (6-8) mL:1 g.

[0015] Further, in step S1, the copolymerization reaction is carried out under light-protected conditions at a reaction temperature of 70-80℃, preferably 72-78℃, for a reaction time of 20-28h, preferably 22-26h. After the reaction is completed, the reaction solution is cooled to room temperature, precipitated with anhydrous ethanol, filtered to obtain crude terpolymer, which is then purified by vacuum drying at a temperature of 70-90℃ for 8-12h.

[0016] Further, in step S2, the mass fraction of the terpolymer in N-methylpyrrolidone is 10-20%, preferably 12-18%, and the metal substrate is selected from 304 stainless steel, nickel-based alloy, aluminum-based alloy or titanium-based alloy.

[0017] Further, the pretreatment steps in step S2 are as follows: ultrasonically clean with acetone and anhydrous ethanol for 15-20 minutes each, with an ultrasonic power of 150-200W and an ultrasonic temperature of 25-30℃. After drying with nitrogen, apply a 1% silane coupling agent-ethanol solution as a primer, where 1% is the mass fraction of the silane coupling agent in the ethanol solution. The silane coupling agent is selected from KH550 or KH570. The primer thickness is 10-20μm. Curing is carried out at 80-85℃ for 30 minutes. The coating method is selected from spin coating, spray coating, or blade coating. Specifically, the spin coating speed is 2000-3000r / min, and the spin coating time is 30-60s; the spray coating pressure is 0.3-0.5MPa, and the spray coating distance is 15-25cm; the blade coating is done with a blade, and the blade gap is 50-150μm.

[0018] Furthermore, in step S3, the photocrosslinking curing uses a high-pressure mercury lamp as the light source, and a photoinitiator is added. The photoinitiator is selected from 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), and the amount of photoinitiator is 0.5-1.5% of the mass of the terpolymer. The photoinitiator is dissolved in N-methylpyrrolidone together with the terpolymer when preparing the coating solution. The wavelength of the light source is 365 nm, and the light intensity is 40-60 mW / cm². 2 The preferred light intensity is 45-55 mW / cm². 2 The irradiation time is 5-10 min, preferably 6-8 min, and the irradiation atmosphere is a nitrogen atmosphere. After photocrosslinking and curing, a pre-drying treatment is performed at a temperature of 60-80℃ for 10-15 min to remove residual solvent from the wet film.

[0019] Furthermore, in step S3, the thermal crosslinking curing adopts a programmed temperature rise method with a heating rate of 4-6℃ / min, preferably 5℃ / min. First, the temperature is raised to 140-160℃ and held for 2-3 hours, preferably raised to 145-155℃ and held for 2.5 hours, then raised to 190-210℃ and held for 4-6 hours, preferably raised to 195-205℃ and held for 4.5-5.5 hours. After the thermal crosslinking curing is completed, it is naturally cooled to room temperature to obtain a high-temperature resistant and oxidation-resistant metal protective coating.

[0020] According to another aspect of the present invention, a high-temperature resistant and oxidation-resistant metal protective coating composite material prepared by the above-described preparation method is provided.

[0021] The beneficial effects of this invention are:

[0022] 1. During the curing process, the vinyltriethoxysilane units in the terpolymer undergo hydrolysis and condensation to form a Si–O–Si inorganic rigid network with extremely high bond energy. This network serves as the core framework of the coating, providing excellent thermal stability and mechanical support, effectively improving the structural integrity of the coating under high-temperature conditions. Simultaneously, 4-acryloyloxybenzophenone is covalently integrated into the molecular backbone. Its conjugated aromatic ring structure not only endows the coating with the ability to capture thermo-oxidative free radicals but also strengthens the interfacial bonding through weak interactions with the metal substrate surface. The La in lanthanum acrylate... 3+ As a high coordination center, it forms multiple coordination crosslinking nodes with the carbonyl and siloxane groups of the polymer side chain, further compacting the molecular chain, significantly reducing the free volume and porosity of the coating, and greatly improving the density.

[0023] 2. After the synergistic effect of photocrosslinking and programmed temperature-controlled thermal crosslinking, a triple interpenetrating dense structure is formed inside the coating, in which organic covalent networks, inorganic silicon-oxygen networks, and rare earth coordination networks are interwoven. At the physical level, this can reduce the generation of potential defects such as pinholes and cracks, and build a relatively continuous and dense molecular-level barrier. This barrier can, to a certain extent, prevent the penetration of oxygen, water vapor, and various corrosive ions into the metal matrix, reduce the probability of oxidation and corrosion, and achieve a good long-term physical barrier protection effect.

[0024] 3. In high-temperature oxidizing service environments, the Si–O–Si inorganic network possesses high bond energy and good thermal stability, preventing significant softening, aging, or thermal decomposition of the coating in oxygen-containing atmospheres at 100-200℃, thus contributing to the long-term stability of the structure. Simultaneously, the benzophenone unit can play a certain quenching role against thermal oxygen free radicals, and La... 3+ It can capture reactive oxygen species in the environment, decompose peroxides, and synergistically inhibit the thermal oxidation chain breaking and degradation of polymer segments, which helps to improve the coating's antioxidant performance and long-term service stability.

[0025] 4. In addition, the siloxane groups in the coating can form relatively strong Si–O–M covalent bonds with the hydroxyl groups on the substrate surface. Combined with the bridging effect of the silane coupling agent in the pretreatment stage, it can achieve a certain degree of good chemical bonding between the coating and the substrate at the molecular level. This helps to alleviate the problem of mismatch in the coefficient of thermal expansion between traditional coatings and metal substrates, and reduces the possibility of cracking, warping or peeling of the coating under temperature fluctuations. This is beneficial to ensuring the integrity and reliability of the protective layer. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, all raw materials used in this invention are commercially available products. Specifically, lanthanum oxide (≥99.9% purity) was purchased from Jining Maikerui Rare Earth Co., Ltd.; acrylic acid (≥99.5% purity) was purchased from Shandong Weijin Chemical Technology Co., Ltd.; vinyltriethoxysilane (VTES) (≥98% purity) was purchased from Jingzhou Yinjie Chemical Co., Ltd.; 4-acryloyloxybenzophenone (CAS: 22535-49-5) (≥99% purity) was purchased from Hubei Shixing Chemical Co., Ltd.; azobisisobutyronitrile (AIBN) (≥99% purity) was purchased from Shandong Jinyueyuan New Materials Co., Ltd.; tetrahydrofuran and N-methylpyrrolidone (≥99.9% purity) were purchased from Nantong Bona Chemical Technology Co., Ltd.; photoinitiator 1173, silane coupling agents KH550 and KH570 were purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0028] Example 1

[0029] A method for preparing a high-temperature resistant and oxidation-resistant metal protective coating composite material includes the following steps:

[0030] S1. Take 10.2g of lanthanum oxide and calcine it at 600℃ for 1h in a muffle furnace at a heating rate of 5℃ / min. After calcineation, allow it to cool naturally to room temperature to obtain activated lanthanum oxide. Take 4.32g of acrylic acid and mix it with activated lanthanum oxide. Add 81.6mL of deionized water and stir the mixture at 50℃ for 2h at a rate of 150r / min to obtain a reaction solution. Distill the reaction solution under reduced pressure at 0.08MPa and 60℃ to obtain a crude product. Wash the crude product twice with anhydrous ethanol, each time using 13.5mL, and dry it at 80℃ for 4h to obtain lanthanum acrylate.

[0031] S2. Take 12.8g vinyltriethoxysilane, 1.4g 4-acryloyloxybenzophenone and 1.1g lanthanum acrylate; add 0.0153g azobisisobutyronitrile, then add 76.5mL tetrahydrofuran, and react under light-protected conditions at 70℃ with continuous stirring (stirring rate of 200r / min) for 20h; after the reaction is completed, cool the reaction solution to room temperature, precipitate with anhydrous ethanol, filter to obtain crude terpolymer, and then purify by vacuum drying at 70℃ for 8h to obtain terpolymer;

[0032] S3. Take 13.2g of terpolymer and add it to 118.8mL of N-methylpyrrolidone. Add 0.066g of photoinitiator 1173 and stir to dissolve at room temperature (25℃) for 30min to prepare a coating solution with a terpolymer mass fraction of 10% (total mass 132g). Select a 304 stainless steel substrate and pretreat it: ultrasonically clean it with 50mL of acetone and 50mL of anhydrous ethanol for 15min each, ultrasonic power 150W, ultrasonic temperature 25℃. After drying with nitrogen, apply a 1% (mass fraction) KH550 silane coupling agent-ethanol solution as a primer with a thickness of 10μm and cure at 80℃ for 30min. Spin-coating is then performed at a speed of 2000r / min for 30s to form a wet film.

[0033] S4. The wet film is subjected to photo-crosslinking curing and thermal crosslinking curing in sequence; the photo-crosslinking curing uses a high-pressure mercury lamp as the light source, with a wavelength of 365nm and a light intensity of 40mW / cm². 2 The material was irradiated in a nitrogen atmosphere for 5 minutes; after photocrosslinking and curing, it was pre-dried at 60℃ for 10 minutes; the thermal crosslinking and curing was carried out using a programmed temperature rise method at a rate of 4℃ / min, first heated to 140℃ and held for 2 hours, then heated to 190℃ and held for 4 hours. After the thermal crosslinking and curing was completed, it was naturally cooled to room temperature to obtain a high-temperature resistant and antioxidant metal protective coating composite material.

[0034] Example 2

[0035] A method for preparing a high-temperature resistant and oxidation-resistant metal protective coating composite material includes the following steps:

[0036] S1. Take 10.2g of lanthanum oxide and calcine it at 650℃ for 2.5h in a muffle furnace at a heating rate of 5℃ / min. After calcineation, allow it to cool naturally to room temperature to obtain activated lanthanum oxide. Take 4.75g of acrylic acid and mix it with activated lanthanum oxide. Add 102mL of alcohol-water mixed solvent (including 68mL of ethanol and 34mL of deionized water) and stir the mixture at 200r / min for 5h at 60℃ to obtain a reaction solution. Distill the reaction solution under reduced pressure at 0.09MPa and 70℃ to obtain a crude product. Wash the crude product twice with anhydrous ethanol, 18mL each time, and dry it at 90℃ for 5h to obtain lanthanum acrylate.

[0037] S2. Take 15.6g of vinyltriethoxysilane, 2.8g of 4-acryloyloxybenzophenone and 2.2g of lanthanum acrylate; add 0.0412g of azobisisobutyronitrile, and then add 144.2mL of N-methylpyrrolidone. Under light-protected conditions, stir continuously at 75℃ (stirring rate of 250r / min) for 24h. After the reaction is completed, cool the reaction solution to room temperature, precipitate with anhydrous ethanol, filter to obtain crude terpolymer, and then purify by vacuum drying at 80℃ for 10h to obtain terpolymer.

[0038] S3. Take 17.8g of terpolymer and add it to 100.4mL of N-methylpyrrolidone. Add 0.178g of photoinitiator 1173 and stir to dissolve at room temperature (28℃) for 45min to prepare a coating solution with a terpolymer mass fraction of 15% (total mass 118.2g). Select a nickel-based alloy substrate and pretreat it: ultrasonically clean it with 50mL of acetone and 50mL of anhydrous ethanol for 18min each, ultrasonic power 180W, ultrasonic temperature 28℃, and after drying with nitrogen, apply a 1% (mass fraction) KH570 silane coupling agent-ethanol solution as a primer with a thickness of 15μm and cure at 82℃ for 30min. Use a spraying method with a spraying pressure of 0.4MPa and a spraying distance of 20cm to form a wet film.

[0039] S4. Perform photo-crosslinking curing and thermal crosslinking curing sequentially on the wet film; the photo-crosslinking curing uses a high-pressure mercury lamp as the light source, with a wavelength of 365nm and a light intensity of 50mW / cm². 2 The material was irradiated in a nitrogen atmosphere for 7 minutes; after photocrosslinking and curing, it underwent pre-drying treatment at a temperature of 70℃ for 12 minutes; the thermal crosslinking and curing was carried out using a programmed temperature rise method at a rate of 5℃ / min, first rising to 150℃ and holding for 2.5 hours, then rising to 200℃ and holding for 5 hours. After the thermal crosslinking and curing was completed, it was naturally cooled to room temperature to obtain a high-temperature resistant and antioxidant metal protective coating composite material.

[0040] Example 3

[0041] A method for preparing a high-temperature resistant and oxidation-resistant metal protective coating composite material includes the following steps:

[0042] S1. Take 10.2g of lanthanum oxide and calcine it at 700℃ for 4h in a muffle furnace at a heating rate of 5℃ / min. After calcineation, allow it to cool naturally to room temperature to obtain activated lanthanum oxide. Take 5.18g of acrylic acid and mix it with activated lanthanum oxide. Add 122.4mL of alcohol-water mixed solvent (including 91.8mL of ethanol and 30.6mL of deionized water) and stir the mixture at 70℃ for 8h at a rate of 250r / min to obtain a reaction solution. Distill the reaction solution under reduced pressure at 0.10MPa and 80℃ to obtain a crude product. Wash the crude product three times with anhydrous ethanol, each time using 14.5mL, and dry it at 100℃ for 6h to obtain lanthanum acrylate.

[0043] S2. Take 18.9g vinyltriethoxysilane, 4.2g 4-acryloyloxybenzophenone and 3.0g lanthanum acrylate; add 0.0783g azobisisobutyronitrile, then add 261mL dioxane, and react under light-protected conditions at 80℃ with continuous stirring (stirring rate of 300r / min) for 28h; after the reaction is completed, cool the reaction solution to room temperature, precipitate with anhydrous ethanol, filter to obtain crude terpolymer, and then purify by vacuum drying at 90℃ for 12h to obtain terpolymer;

[0044] S3. Take 21.5g of terpolymer and add it to 86mL of N-methylpyrrolidone. Add 0.3225g of photoinitiator 1173 and stir to dissolve at room temperature (30℃) for 60min to prepare a coating solution with a terpolymer mass fraction of 20% (total mass 107.5g). Select a titanium-based alloy substrate and pretreat it: ultrasonically clean it with 50mL of acetone and 50mL of anhydrous ethanol for 20min each, ultrasonic power 200W, ultrasonic temperature 30℃, and then blow it dry with nitrogen. Apply a 1% (mass fraction) KH550 silane coupling agent-ethanol solution as a primer with a thickness of 20μm and cure it at 85℃ for 30min. Use a blade coating method with a blade gap of 150μm to form a wet film.

[0045] S4. Perform photo-crosslinking curing and thermal crosslinking curing sequentially on the wet film; the photo-crosslinking curing uses a high-pressure mercury lamp as the light source, with a wavelength of 365nm and a light intensity of 60mW / cm². 2 The material was irradiated in a nitrogen atmosphere for 10 minutes; after photocrosslinking and curing, it was pre-dried at 80℃ for 15 minutes; the thermal crosslinking and curing was carried out using a programmed temperature rise method at a rate of 6℃ / min, first heated to 160℃ and held for 3 hours, then heated to 210℃ and held for 6 hours. After the thermal crosslinking and curing was completed, it was naturally cooled to room temperature to obtain a high-temperature resistant and antioxidant metal protective coating composite material.

[0046] Example 4

[0047] A method for preparing a high-temperature resistant and oxidation-resistant metal protective coating composite material includes the following steps:

[0048] S1. Take 10.2g of lanthanum oxide and calcine it at 630℃ for 3h in a muffle furnace at a heating rate of 5℃ / min. After calcineation, allow it to cool naturally to room temperature to obtain activated lanthanum oxide. Take 4.96g of acrylic acid and mix it with activated lanthanum oxide. Add 91.8mL of alcohol-water mixed solvent (including 68.85mL of ethanol and 22.95mL of deionized water) and stir the mixture at 58℃ for 6h at a rate of 220r / min to obtain a reaction solution. Distill the reaction solution under reduced pressure at 0.09MPa and 75℃ to obtain a crude product. Wash the crude product twice with anhydrous ethanol, 16mL each time, and dry it at 85℃ for 5h to obtain lanthanum acrylate.

[0049] S2. Take 16.2g vinyltriethoxysilane, 3.5g 4-acryloyloxybenzophenone and 2.6g lanthanum acrylate; add 0.0669g azobisisobutyronitrile, then add 181.8mL N-methylpyrrolidone, and react under light-protected conditions at 76℃ with continuous stirring (stirring rate of 260r / min) for 25h; after the reaction is completed, cool the reaction solution to room temperature, precipitate with anhydrous ethanol, filter to obtain crude terpolymer, and then purify by vacuum drying at 85℃ for 11h to obtain terpolymer;

[0050] S3. Take 19.5g of terpolymer and add it to 87.8mL of N-methylpyrrolidone. Add 0.234g of photoinitiator 1173 and stir to dissolve at room temperature (29℃) for 50min to prepare a coating solution with a terpolymer mass fraction of 18% (total mass 107.3g). Select an aluminum-based alloy substrate and pretreat it: ultrasonically clean it for 19min each with 50mL of acetone and 50mL of anhydrous ethanol, ultrasonic power 190W, ultrasonic temperature 29℃, and after drying with nitrogen, apply a 1% (mass fraction) KH570 silane coupling agent-ethanol solution as a primer with a thickness of 18μm and cure at 83℃ for 30min. Use a spraying method with a spraying pressure of 0.45MPa and a spraying distance of 22cm to form a wet film.

[0051] S4. Perform photo-crosslinking curing and thermal crosslinking curing sequentially on the wet film; the photo-crosslinking curing uses a high-pressure mercury lamp as the light source, with a wavelength of 365nm and a light intensity of 52mW / cm². 2The material was irradiated under a nitrogen atmosphere for 8 minutes; after photocrosslinking and curing, it underwent pre-drying treatment at a temperature of 75℃ for 13 minutes; the thermal crosslinking and curing was carried out using a programmed temperature rise method at a rate of 5.5℃ / min, first rising to 155℃ and holding for 2.8 hours, then rising to 205℃ and holding for 5.5 hours. After the thermal crosslinking and curing was completed, it was naturally cooled to room temperature to obtain a high-temperature resistant and antioxidant metal protective coating composite material.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that vinyltriethoxysilane is not added in step S2, while the remaining steps are the same as in Example 1.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 2 is that 4-acryloyloxybenzophenone is not added in step S2, while the other steps are the same as in Example 2.

[0056] Comparative Example 3

[0057] The difference between this comparative example and Example 3 is that lanthanum acrylate is not added in step S2, while the remaining steps are the same as in Example 3.

[0058] The materials obtained in Examples 1-4 and Comparative Examples 1-3 were prepared into samples with dimensions of 50 mm × 50 mm × 1 mm. Three parallel samples were prepared for each type of sample. The samples were ultrasonically cleaned with anhydrous ethanol for 10 min to remove residual impurities and oil stains from the surface. They were then placed in a constant temperature drying oven and dried at 80°C for 30 min. After being removed, they were cooled to room temperature in a desiccator for later use. The coating thickness of each sample was measured at 5 different points on each sample, and the average value was taken as the coating thickness of that sample.

[0059] (I) Coating adhesion test

[0060] According to GB / T 5210-2006 "Paints and Varnishes - Adhesion Test by Pull-Off Method", the adhesion strength between the coating and the substrate of each sample was tested using an adhesion tester. Three different points were tested for each parallel sample, and the test values ​​were recorded. The average value of the three points was taken as the adhesion strength data of the sample. If coating peeling, cracking, or other phenomena occurred, it was recorded as unqualified.

[0061] (II) High temperature resistance test

[0062] First, weigh each pretreated parallel sample using an electronic balance and record the initial mass (m0) accurate to 0.0001g. Place the sample in a muffle furnace and use a programmed heating method with a heating rate of 5℃ / min to heat to 200℃, and hold at that temperature for 100h. After the holding period, turn off the muffle furnace and allow the sample to cool naturally to room temperature. Remove the sample and gently wipe the surface with anhydrous ethanol to remove surface dust. Weigh the sample again (m1) accurate to 0.0001g. Calculate the mass change rate of the sample using the formula: Mass change rate (%) = (m1-m0) / m0 × 100%.

[0063] (III) Antioxidant performance test

[0064] The high-temperature oxidation weight loss method was used, and the test was conducted simultaneously with the high-temperature resistance test (for samples from the same batch). The oxidation weight loss rate was calculated by combining the initial mass (m0) and the mass after high-temperature holding (m1) measured in the above steps. The formula is: Oxidation weight loss rate (g / m0) 2 ) = (m0 - m1) / S, where S is the surface area of ​​the sample (unit: m). 2 ).

[0065] The results are shown in Table 1:

[0066] Table 1. Test results of Examples 1-4 and Comparative Examples 1-3

[0067]

[0068] As shown in Table 1, the average adhesion strength of the coatings in Examples 1-4 ranged from 5.8 to 7.5 MPa, all exhibiting good adhesion. This is because the siloxane groups in the coating can form relatively strong Si–O–M covalent bonds with the hydroxyl groups on the substrate surface. Simultaneously, the silane coupling agent in the pretreatment stage acts as a bridge, achieving a good chemical bond between the coating and the substrate at the molecular level to a certain extent, thereby effectively improving the adhesion between the coating and the substrate.

[0069] Comparative Example 1, without the addition of vinyltriethoxysilane, showed an average adhesion strength of 3.2 MPa; Comparative Example 2, without the addition of 4-acryloyloxybenzophenone, showed an average adhesion strength of 4.5 MPa; and Comparative Example 3, without the addition of lanthanum acrylate, showed an average adhesion strength of 4.1 MPa. This indicates that vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate all have significant effects on coating adhesion. Vinyltriethoxysilane participates in the formation of the Si–O–Si inorganic rigid network, providing mechanical support for the coating; 4-acryloyloxybenzophenone strengthens interfacial bonding through weak interactions with the metal substrate surface; and the La in lanthanum acrylate... 3+The formation of multiple coordination crosslinking nodes and the tight stacking of molecular chains work together to ensure a good bond between the coating and the substrate. The absence of any one of these components would weaken this bonding effect.

[0070] The average mass change rate of Examples 1-4 was between 0.15% and 0.32%, indicating that the coating has good stability at high temperatures. This is because the Si–O–Si inorganic network has high bond energy and good thermal stability, and is not prone to significant softening, aging, or thermal decomposition in an oxygen-containing atmosphere at 100-200℃, which helps maintain the long-term stability of the structure and results in a small mass change of the coating at high temperatures.

[0071] The average mass change rate of Comparative Example 1 was 0.87%, Comparative Example 2 was 0.63%, and Comparative Example 3 was 0.75%, all significantly higher than that of the Examples. This is because the Comparative Examples lacked vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate, respectively. The Si–O–Si inorganic network formed by vinyltriethoxysilane is a key structure for the high-temperature resistance of the coating; 4-acryloyloxybenzophenone and lanthanum acrylate synergistically inhibit the thermal oxidative chain scission and degradation of polymer segments. Without these components, the coating is more prone to softening, aging, or thermal decomposition at high temperatures, leading to increased mass change.

[0072] The average oxidative weight loss rates of Examples 1-4 were 0.42-0.68 g / m³. 2 Between these components, good antioxidant properties are observed. On one hand, the Si–O–Si inorganic network provides a physical barrier, hindering the penetration of oxygen into the metal matrix; on the other hand, the benzophenone unit can play a certain quenching role against thermal oxygen free radicals, and La... 3+ It can capture reactive oxygen species in the environment, decompose peroxides, and synergistically inhibit the thermal oxidative chain breaking and degradation of polymer segments, thereby reducing the oxidative weight loss of the coating at high temperatures.

[0073] The average oxidative weight loss rate of Comparative Example 1 was 1.52 g / m³. 2 Comparative Example 2 was 1.05 g / m³. 2 Comparative Example 3 was 1.23 g / m³. 2 The results were significantly higher than in the examples. This indicates that vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate all play important roles in the antioxidant process. The absence of vinyltriethoxysilane affects the formation of the Si–O–Si inorganic network, weakening the physical barrier effect; the lack of 4-acryloyloxybenzophenone and lanthanum acrylate reduces the quenching ability of thermo-oxidative free radicals and the ability to capture reactive oxygen species, making the coating more susceptible to oxidation and increasing the oxidation weight loss rate.

[0074] In summary, the present invention utilizes the synergistic effect of vinyltriethoxysilane, 4-acryloyloxybenzophenone, and lanthanum acrylate, combined with a reasonable preparation process, to prepare a high-temperature resistant and antioxidant metal protective coating composite material with excellent coating adhesion, high-temperature stability, and antioxidant properties.

[0075] In the description of this specification, the reference to terms such as "embodiment," "various embodiments," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or preparation example is included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature resistant and oxidation-resistant metal protective coating composite material, characterized in that, Includes the following steps: S1. A copolymer of vinyltriethoxysilane, 4-acryloyloxybenzophenone and lanthanum acrylate is obtained by copolymerization. S2. Add the terpolymer to N-methylpyrrolidone to obtain a coating solution, and coat the coating solution onto the surface of the pretreated metal substrate to form a wet film; S3. The wet film is subjected to photocrosslinking curing and thermal crosslinking curing in sequence to obtain a high-temperature resistant and antioxidant metal protective coating composite material.

2. The preparation method according to claim 1, characterized in that, Lanthanum acrylate in step S1 is obtained through the following steps: Lanthanum oxide was calcined at 600-700℃ for 1-4 hours to obtain activated lanthanum oxide. The activated lanthanum oxide was mixed with acrylic acid, and deionized water or an alcohol-water mixture was added. The mixture was stirred at 50-70℃ for 2-8 hours to obtain a reaction solution. The reaction solution was distilled under reduced pressure to obtain a crude product. The crude product was washed and dried to obtain lanthanum acrylate.

3. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of vinyltriethoxysilane, 4-acryloyloxybenzophenone to lanthanum acrylate is (12.8-18.9):(1.4-4.2):(1.1-3.0).

4. The preparation method according to claim 1, characterized in that, The copolymerization reaction in step S1 also includes an initiator and a solvent. The initiator is selected from azobisisobutyronitrile, and the amount of initiator used is 0.1-0.3% of the total mass of vinyltriethoxysilane, 4-acryloyloxybenzophenone and lanthanum acrylate. The solvent is selected from one of tetrahydrofuran, N-methylpyrrolidone, dioxane or ethyl acetate, and the ratio of the solvent to the total mass of vinyltriethoxysilane, 4-acryloyloxybenzophenone and lanthanum acrylate is (5-10) mL: 1 g.

5. The preparation method according to claim 1, characterized in that, In step S1, the copolymerization reaction is carried out under light-protected conditions at a temperature of 70-80℃ for 20-28 hours.

6. The preparation method according to claim 1, characterized in that, In step S2, the mass fraction of the terpolymer in N-methylpyrrolidone is 10-20%, and the metal substrate is selected from 304 stainless steel, nickel-based alloy, aluminum-based alloy or titanium-based alloy.

7. The preparation method according to claim 1, characterized in that, The pretreatment steps in step S2 are as follows: ultrasonically clean with acetone and anhydrous ethanol for 15-20 minutes each, blow dry, apply a 1% silane coupling agent-ethanol solution as a primer, and cure at 80-85℃ for 30 minutes. The coating method is selected from spin coating, spray coating or scraping coating.

8. The preparation method according to claim 1, characterized in that, In step S3, the photocrosslinking curing uses a high-pressure mercury lamp as the light source, with a photoinitiator added. The light source wavelength is 365 nm, and the light intensity is 40-60 mW / cm². 2 The irradiation time is 5-10 minutes, and the irradiation atmosphere is a nitrogen atmosphere.

9. The preparation method according to claim 1, characterized in that, In step S3, the thermal crosslinking curing adopts a programmed temperature rise method with a temperature rise rate of 4-6℃ / min. First, the temperature is raised to 140-160℃ and held for 2-3 hours, then raised to 190-210℃ and held for 4-6 hours. After the thermal crosslinking curing is completed, it is naturally cooled to room temperature to obtain a high-temperature resistant and oxidation-resistant metal protective coating.

10. A high-temperature resistant and oxidation-resistant metal protective coating composite material prepared by the preparation method according to any one of claims 1-9.

Images