Preparation process of high-temperature-resistant metal protective coating

Abstract

The invention discloses a preparation process of a high-temperature-resistant metal protective coating, and relates to the technical field of protective coatings. According to the coating, an inorganic material which is stable at high temperature is compounded with an organic polymer to form a matrix with excellent high-temperature resistance, and an anti-corrosion filler is added to improve the corrosion resistance and the wear resistance. Through a specific preparation process, the coating and the metal substrate are tightly combined to form a compact protective barrier. The coating provided by the invention has excellent high-temperature resistance, corrosion resistance and adhesive force, and is suitable for metal structure protection in a high-temperature environment.

Description

Technical Field

[0001] This invention relates to the field of protective coating technology, and in particular to a preparation process for a high-temperature resistant metal protective coating. Background Technology

[0002] Metallic materials are widely used in various fields of industrial production, such as aerospace, petrochemicals, machinery manufacturing, and energy and power. However, under high-temperature and corrosive environments, the surface of metallic materials is prone to oxidation, corrosion, or wear, which not only leads to a decline in equipment performance but can also cause serious safety hazards and economic losses. Therefore, developing high-performance protective coatings for metals has become an important research direction in the field of materials protection.

[0003] Existing metal protective coatings can be mainly classified into the following categories: Inorganic coatings: Inorganic coatings are typically made of oxides, silicates, or ceramic materials and possess high high-temperature resistance. However, these coatings have poor flexibility and adhesion, and are prone to cracking and peeling under thermal cycling and mechanical impact. Furthermore, their corrosion resistance is relatively limited, making them unsuitable for complex operating conditions.

[0004] Organic coatings: Organic coatings use polymers such as epoxy resin, polyurethane, and polyimide as a matrix, possessing good flexibility and adhesion. However, organic coatings generally have poor high-temperature resistance, especially prone to thermal decomposition in environments above 300°C, leading to coating failure. Furthermore, organic coatings also have certain limitations in abrasion resistance and corrosion resistance.

[0005] Composite coatings: Composite coatings combine inorganic materials and organic polymers, possessing both the high-temperature resistance of inorganic coatings and the flexibility and adhesion of organic coatings. However, existing composite coatings still face technical bottlenecks in achieving a balance between high-temperature resistance, corrosion resistance, and adhesion, particularly in applications under high-temperature and highly corrosive environments, where performance needs improvement.

[0006] However, current coating preparation processes also have certain limitations, such as: Poor dispersion of coating materials and easy aggregation of fillers in the matrix lead to uneven coating performance; insufficient interfacial bonding between the coating and the metal substrate prevents the formation of a dense protective barrier; improper control of the curing process can lead to coating cracking or performance degradation.

[0007] In summary, existing metal protective coatings struggle to simultaneously meet the multiple requirements of high-temperature resistance, corrosion resistance, and adhesion under the combined effects of high temperature, corrosion, and mechanical stress. Therefore, there is an urgent need to develop a high-performance, high-temperature resistant metal protective coating with a rational material system and optimized process to meet the increasingly complex environmental requirements of industrial production. Summary of the Invention

[0008] To address this technical challenge, the present invention provides a metal protective coating with excellent high-temperature resistance, corrosion resistance and adhesion, as well as its preparation process, providing reliable protection for metal structures in high-temperature environments.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A process for preparing a high-temperature resistant metal protective coating, characterized in that the coating is composed of the following components in parts by mass: High-temperature stable inorganic materials: 30-50 parts; Organic polymer: 20-40 parts; High-temperature resistant and corrosion-resistant filler: 10-30 parts; Solvent: 5-10 parts; Dispersant: 0.2-0.5 parts; Wetting agent: 0.1-0.3 parts; Defoamer: 0.1-0.3 parts.

[0010] In some specific embodiments of the present invention, the high-temperature stable inorganic material is selected from at least one of sodium silicate, potassium silicate, calcium aluminate, and magnesium aluminate.

[0011] In some specific embodiments of the present invention, the organic polymer is selected from bisphenol A type epoxy resin or bisphenol F type epoxy resin.

[0012] In some specific embodiments of the present invention, the preparation method of the high-temperature resistant and corrosion-resistant filler is as follows: By weight, 4-8 parts of allyltrimethoxysilane, 58-72 parts of flake graphite (particle size 1-5 μm), 30-60 parts of silicon carbide micro powder (particle size 0.5-3 μm), 100-120 parts of spherical alumina (particle size 1-10 μm), and 1200-1500 parts of dichloroethane are added to reactor 1, and the mixture is stirred and reacted at room temperature for 150 to 200 minutes. Then add 0.08-0.6 parts of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex, 11-22 parts of diaminetetrachlorotitanate (CAS No. 15719-81-0), and 1-4 parts of potassium hydroxide. Continue to stir and react at 70-80℃ for 100 to 150 minutes, filter, and dry to obtain high-temperature resistant and corrosion-resistant filler.

[0013] In some specific embodiments of the present invention, the preparation method of the 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex is as follows: By weight, 17-34 parts of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid, 20-40 parts of lanthanum chloride, and 200-300 parts of water are mixed and reacted at 70-80°C for 100-140 minutes. The water is removed by distillation and then dried under vacuum to obtain the 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex.

[0014] In some specific embodiments of the present invention, the solvent is selected from at least one of xylene, toluene, ethyl acetate, ethyl butyrate, cyclohexanone, and methyl isobutyl ketone.

[0015] In some specific embodiments of the present invention, the dispersant is selected from at least one of sodium dodecylbenzenesulfonate, fatty alcohol polyoxyethylene ether, BYK-110, and BYK-163.

[0016] In some specific embodiments of the present invention, the wetting agent is selected from at least one of BYK-333, TEGO Wet 265, Dynol 800, isopropanol, and ethoxylated alcohols.

[0017] In some specific embodiments of the present invention, the defoamer is selected from at least one of BYK-141, BYK-024, TEGOAirex, and polyether-modified polysiloxane.

[0018] In some specific embodiments of the present invention, the method for preparing the coating is as follows: (1) Mixing and dispersing: Weigh out the high-temperature stable inorganic material, organic polymer, anti-corrosion filler, solvent and additives according to the mass fractions, and place the mixed material in a dispersion device or ball mill for grinding. The specific conditions are as follows: Grinding time: 4-8 hours; Speed: 300-500 rpm; The average particle size is controlled between 0.5 and 10 μm, preferably between 1 and 5 μm.

[0019] (2) Coating preparation: The ground coating slurry is uniformly coated onto the surface of the metal substrate using any of the following methods: Spraying: Spray gun diameter 0.3-0.5 mm, spraying pressure 0.2-0.4 MPa, coating thickness controlled at 50-150 μm; Brush coating: Multiple coats, each coat is 20-50 μm thick; Dip coating: Coating time is 30-120 seconds. After ensuring even coating, allow it to dry naturally.

[0020] (3) Curing treatment: The coated metal substrate is subjected to curing treatment under the following process conditions: Curing temperature: 150-200°C; Curing time: 2-4 hours; Slowly increase the temperature to the target temperature to avoid coating cracking.

[0021] Enhanced corrosion protection mechanism: 2,5-Dimethyl-2,4-hexadiene complex with lanthanum 2,5-Dimethyl-2,4-hexadiene itself does not possess significant anti-corrosion properties, but its derivatives or complexes may improve the corrosion resistance of materials by forming a protective film or participating in chemical reactions.

[0022] The application of lanthanum complexes in corrosion protection is mainly due to their ability to form stable oxide or hydroxide layers, which effectively prevent the intrusion of corrosive media. Furthermore, lanthanum complexes can also improve the corrosion resistance of materials by adsorbing onto metal surfaces to form a protective film.

[0023] 2,5-Dimethyl-2,4-hexadiene and diaminetetrachlorotitanate The application of diammonium tetrachlorotitanate in corrosion protection mainly relies on the interaction between its hydrolysis products and the metal surface. Titanate can hydrolyze in water to produce substances such as titanium hydroxide, which can deposit on the metal surface, forming a dense protective film that prevents further corrosion.

[0024] In summary, the effectiveness of 2,5-dimethyl-2,4-hexadiene complexes with lanthanum and diaminetetrachlorotitanate in high-temperature corrosion-resistant fillers primarily relies on their unique molecular structures and steric hindrance effects. Lanthanum complexes enhance corrosion resistance by forming stable oxide or hydroxide layers, while diaminetetrachlorotitanate forms a protective film through the interaction of its hydrolysis products with the metal surface. These properties enable these compounds to maintain good corrosion resistance even at high temperatures.

[0025] Technical effect 1. Excellent high temperature resistance The coating incorporates high-temperature stable inorganic materials and heat-resistant anti-corrosion fillers, which can maintain a stable structure in high-temperature environments of 300-500°C without decomposition, cracking or performance degradation, thus significantly improving the service life of the coating under high-temperature conditions.

[0026] 2. Excellent corrosion resistance The coating, through a composite design of inorganic materials and organic polymers, combined with highly efficient anti-corrosion fillers, forms a dense anti-corrosion barrier that can effectively resist the erosion of acidic and alkaline media.

[0027] 3. Excellent adhesion and impact resistance By optimizing the formulation of dispersants and wetting agents, the coating enhances its wettability and penetration onto the surface of the metal substrate; after curing, the coating forms a cross-linked and dense adhesive layer that is firmly bonded to the metal substrate. Detailed Implementation

[0028] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0029] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0030] Example 1: Materials preparation: High-temperature stable inorganic material: Weigh 30 g of sodium silicate; Organic polymer: 20 g bisphenol A type epoxy resin; High-temperature resistant and corrosion-resistant filler: 10g Preparation method: 4 g allyltrimethoxysilane, 58 g flake graphite (particle size 1-5 μm), 30 g silicon carbide micro powder (particle size 0.5-3 μm), 100 g spherical alumina (particle size 1-10 μm), and 1200 g dichloroethane were added to reactor 1 and stirred at room temperature for 150 minutes. Then, 0.08 g of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex (prepared by mixing 17 g of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid, 20 g of lanthanum chloride, and 200 g of water, reacting at 70°C for 100 minutes, distilling off the water, and then drying under vacuum), 11 g diaminetetrachlorotitanate (CAS No. 15719-81-0), and 1 g potassium hydroxide were added. The mixture was stirred at 70°C for another 100 minutes, filtered, and dried to obtain a high-temperature resistant and corrosion-resistant filler. Solvent: 5 g xylene; Dispersant: 0.2 g sodium dodecylbenzenesulfonate; Wetting agent: 0.1 g BYK-333; Defoamer: 0.1 g BYK-141.

[0031] Coating preparation: Mixing and dispersing: The mixed materials were placed in a ball mill for grinding for 4 hours at a speed of 300 rpm, and the average particle size was controlled at 0.5-10 μm; Coating preparation: The grinding coating slurry was uniformly coated onto the surface of the metal substrate using a spraying method with a spray gun diameter of 0.3 mm and a spraying pressure of 0.2 MPa. The coating thickness was controlled between 50-150 μm. Curing treatment: The coated metal substrate is cured at a temperature of 150°C for 2 hours. The temperature is slowly increased to the target temperature to avoid cracking of the coating.

[0032] Example 2: Materials preparation: High-temperature stable inorganic material: Weigh 40 g of potassium silicate; Organic polymer: 30 g bisphenol F type epoxy resin; High-temperature resistant and corrosion-resistant filler: 15g Preparation method: 6 g allyltrimethoxysilane, 65 g flake graphite (particle size 1-5 μm), 45 g silicon carbide micro powder (particle size 0.5-3 μm), 110 g spherical alumina (particle size 1-10 μm), and 1350 g dichloroethane were added to reactor 1 and stirred at room temperature for 175 minutes. Then, 0.3 g 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex (prepared by mixing 25 g 2,5-dimethyl-2,4-hexadiene dicarboxylic acid, 30 g lanthanum chloride, and 250 g water, reacting at 75°C for 120 minutes, distilling off the water, and then drying under vacuum), 16 g diaminetetrachlorotitanate (CAS No. 15719-81-0), and 2.5 g potassium hydroxide were added, and the mixture was stirred at 75°C for another 125 minutes. After filtration and drying, a high-temperature resistant and corrosion-resistant filler was obtained. Solvent: 7.5 g toluene; Dispersant: 0.35 g fatty alcohol polyoxyethylene ether; Wetting agent: 0.2 g TEGO Wet 265; Defoamer: 0.2 g BYK-024.

[0033] Coating preparation: Mixing and dispersing: The mixed materials are placed in a dispersing device for grinding. The grinding time is 6 hours, the rotation speed is 400 rpm, and the average particle size is controlled at 1-5 μm. Coating preparation: The grinding coating slurry is uniformly coated on the surface of the metal substrate by brushing, with multiple coatings and a single coating thickness of 20-50 μm. Curing treatment: The coated metal substrate is cured at a temperature of 175°C for 3 hours. The temperature is slowly increased to the target temperature to avoid cracking of the coating.

[0034] Example 3: Materials preparation: High-temperature stable inorganic material: Weigh 50 g of calcium aluminate; Organic polymer: 40 g bisphenol A type epoxy resin; High-temperature resistant and corrosion-resistant filler: 20g Preparation method: 8 g allyltrimethoxysilane, 72 g flake graphite (particle size 1-5 μm), 60 g silicon carbide micro powder (particle size 0.5-3 μm), 120 g spherical alumina (particle size 1-10 μm), and 1500 g dichloroethane were added to reactor 1 and stirred at room temperature for 200 minutes. Then, 0.6 g of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex (prepared by mixing 34 g of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid, 40 g of lanthanum chloride, and 300 g of water, reacting at 80°C for 140 minutes, distilling off the water, and then drying in vacuum), 22 g diaminetetrachlorotitanate (CAS No. 15719-81-0), and 4 g potassium hydroxide were added, and the mixture was stirred at 80°C for another 150 minutes. After filtration and drying, a high-temperature resistant and corrosion-resistant filler was obtained. Solvent: 10 g ethyl acetate; Dispersant: 0.5 g BYK-163; Wetting agent: 0.3 g Dynol 800; Defoamer: 0.3 g TEGO Airex.

[0035] Coating preparation: Mixing and dispersing: The mixed materials were placed in a ball mill for grinding for 8 hours at a speed of 500 rpm, and the average particle size was controlled at 0.5-10 μm; Coating preparation: The dip coating method is used, with a coating time of 30-120 seconds. After uniformity is controlled, the coating is allowed to dry naturally. The ground coating slurry is then uniformly coated on the surface of the metal substrate. Curing treatment: The coated metal substrate is cured at a temperature of 200°C for 4 hours. The temperature is slowly increased to the target temperature to avoid cracking of the coating.

[0036] Example 4: Materials preparation: High-temperature stable inorganic material: Weigh out 35 g of magnesium aluminate and 15 g of sodium silicate; Organic polymer: 25 g bisphenol F type epoxy resin; High-temperature resistant and corrosion-resistant filler: 30g Preparation method: 5 g allyltrimethoxysilane, 60 g flake graphite (particle size 1-5 μm), 40 g silicon carbide micro powder (particle size 0.5-3 μm), 105 g spherical alumina (particle size 1-10 μm), and 1300 g dichloroethane were added to reactor 1 and stirred at room temperature for 160 minutes. Then, 0.2 g 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex (prepared by mixing 20 g 2,5-dimethyl-2,4-hexadiene dicarboxylic acid, 25 g lanthanum chloride, and 220 g water, reacting at 72°C for 110 minutes, distilling off the water, and then drying under vacuum), 14 g diaminetetrachlorotitanate (CAS No. 15719-81-0), and 2 g potassium hydroxide were added. The mixture was stirred at 72°C for another 110 minutes, filtered, and dried to obtain a high-temperature resistant and corrosion-resistant filler. Solvent: a combination of 6 g cyclohexanone and 4 g methyl isobutyl ketone; Dispersant: a combination of 0.3 g BYK-110 and 0.2 g sodium dodecylbenzenesulfonate; Wetting agent: a combination of 0.15 g BYK-333 and 0.15 g ethoxylated alcohol; Defoamer: 0.15 g BYK-141 combined with 0.15 g polyether-modified polysiloxane.

[0037] Coating preparation: Mixing and dispersing: The mixed materials are placed in a dispersing device for grinding for 5 hours at a speed of 350 rpm, and the average particle size is controlled at 1-5 μm; Coating preparation: The grinding coating slurry was uniformly coated onto the surface of the metal substrate using a spraying method with a spray gun diameter of 0.4 mm and a spraying pressure of 0.3 MPa. The coating thickness was controlled between 50-150 μm. Curing treatment: The coated metal substrate is cured at a temperature of 160°C for 2.5 hours. The temperature is slowly increased to the target temperature to avoid cracking of the coating.

[0038] Comparative Example 1: The difference between this example and Example 1 is that the high-temperature resistant and corrosion-resistant filler is replaced with an equal amount of flake graphite (particle size 1-5 μm).

[0039] Comparative Example 2: The difference between this example and Example 1 is that 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex is not added during the preparation of the high-temperature resistant and corrosion-resistant filler.

[0040] Comparative Example 3: The difference between this example and Example 1 is that diaminetetrachlorotitanate is not added during the preparation of the high-temperature resistant and corrosion-resistant filler.

[0041] Test methods and test results 1) High temperature resistance test Test method: The metal substrate (50 mm × 50 mm × 3 mm) coated with the test coating was placed in a high-temperature furnace and heated at the following temperature gradient: 300°C, 400°C, and 500°C, holding at each temperature for 2 hours. The cracking, peeling, or decomposition of the coating surface was observed, and the structural integrity of the coating was examined under a microscope.

[0042] Test results: Table 1. High Temperature Resistance Test Results 300°C 400°C 500°C Example 1 No change No change No significant changes Example 2 No change No change No significant changes Example 3 No change No change No significant changes Example 4 No change No change No change Comparative Example 1 cracking Partial peeling Severe peeling Comparative Example 2 No change microcracks Partial peeling Comparative Example 3 No change microcracks Partial peeling 2) Corrosion resistance test Test method: Using the ASTM B117 standard salt spray test method, metal samples coated with the test coating were exposed to a 5% sodium chloride solution atomization environment for 1000 consecutive hours. Results were recorded at 500h and 1000h.

[0043] Test results: Table 2 Corrosion Resistance Test Results 500h 1000h Example 1 No corrosion spots No corrosion spots Example 2 No corrosion spots No corrosion spots Example 3 No corrosion spots No corrosion spots Example 4 No corrosion spots No corrosion spots Comparative Example 1 A few corrosion spots Noticeable foaming Comparative Example 2 No corrosion spots A few corrosion spots Comparative Example 3 No corrosion spots A few corrosion spots 3) Adhesion test Test method: The adhesion of the coating was tested using the pull-out method according to ASTM D4541 standard.

[0044] Using standard testing equipment, the maximum pull-out force when the coating peels off the substrate was recorded, in MPa.

[0045] Test results: Table 3 Adhesion Test Results Average adhesion (MPa) Example 1 12.3 Example 2 12.7 Example 3 12.5 Example 4 13.1 Comparative Example 1 11.7 Comparative Example 2 12.1 Comparative Example 3 12.0 The coating in the example showed significantly better performance than the coating in the comparative example in terms of high temperature resistance, corrosion resistance, and adhesion, verifying the advanced nature and applicability of the technology of the present invention.

[0046] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A preparation process for a high-temperature resistant metal protective coating, characterized in that, The coating is composed of the following components in parts by mass: High-temperature stable inorganic materials: 30-50 parts; Organic polymer: 20-40 parts; High-temperature resistant and corrosion-resistant filler: 10-30 parts; Solvent: 5-10 parts; Dispersant: 0.2-0.5 parts; Wetting agent: 0.1-0.3 parts; Defoamer: 0.1-0.3 parts; The high-temperature resistant and corrosion-resistant filler is prepared by reacting allyltrimethoxysilane, 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex, and diaminetetrachlorotitanate.

2. The preparation process of a high-temperature resistant metal protective coating according to claim 1, characterized in that: The high-temperature stable inorganic material is selected from at least one of sodium silicate, potassium silicate, calcium aluminate, and magnesium aluminate.

3. The preparation process of a high-temperature resistant metal protective coating according to claim 1, characterized in that: The organic polymer is selected from bisphenol A type epoxy resin or bisphenol F type epoxy resin.

4. The preparation process of a high-temperature resistant metal protective coating according to claim 1, characterized in that: The preparation method of the high-temperature resistant and corrosion-resistant filler: By weight, 4-8 parts of allyltrimethoxysilane, 58-72 parts of flake graphite (particle size 1-5 μm), 30-60 parts of silicon carbide micro powder (particle size 0.5-3 μm), 100-120 parts of spherical alumina (particle size 1-10 μm), and 1200-1500 parts of dichloroethane are added to reactor 1, and the mixture is stirred and reacted at room temperature for 150 to 200 minutes. Then add 0.08-0.6 parts of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex, 11-22 parts of diammonium tetrachlorotitanate, and 1-4 parts of potassium hydroxide. Continue to stir and react at 70-80℃ for 100 to 150 minutes, filter, and dry to obtain high-temperature resistant and corrosion-resistant filler.

5. The preparation process of a high-temperature resistant metal protective coating according to claim 4, characterized in that: The preparation method of the 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex is as follows: By weight, 17-34 parts of 2,5-dimethyl-2,4-hexadiene dicarboxylic acid, 20-40 parts of lanthanum chloride, and 200-300 parts of water are mixed and reacted at 70-80°C for 100-140 minutes. The water is removed by distillation and then dried under vacuum to obtain the 2,5-dimethyl-2,4-hexadiene dicarboxylic acid / lanthanum complex.

6. The preparation process of a high-temperature resistant metal protective coating according to claim 1, characterized in that: The solvent is selected from at least one of xylene, toluene, ethyl acetate, ethyl butyrate, cyclohexanone, and methyl isobutyl ketone.

7. The preparation process of a high-temperature resistant metal protective coating according to claim 1, characterized in that: The dispersant is selected from at least one of sodium dodecylbenzenesulfonate, fatty alcohol polyoxyethylene ether, BYK-110, and BYK-163.

8. The preparation process of a high-temperature resistant metal protective coating according to claim 1, characterized in that: The wetting agent is selected from at least one of BYK-333, TEGO Wet 265, Dynol 800, isopropanol, and ethoxylated alcohols.

9. The preparation process of a high-temperature resistant metal protective coating according to claim 1, characterized in that: The defoamer is selected from at least one of BYK-141, BYK-024, TEGO Airex, and polyether-modified polysiloxane.

10. The preparation process of a high-temperature resistant metal protective coating according to claims 1-9, characterized in that: The coating preparation method: (1) Mixing and dispersing: Weigh out the high-temperature stable inorganic material, organic polymer, anti-corrosion filler, solvent and additives according to the mass fractions, and place the mixed material in a dispersion device or ball mill for grinding. The specific conditions are as follows: Grinding time: 4-8 hours; Speed: 300-500 rpm; The average particle size is controlled between 0.5 and 10 μm, preferably between 1 and 5 μm; (2) Coating preparation: The ground coating slurry is uniformly coated onto the surface of the metal substrate using any of the following methods: Spraying: Spray gun diameter 0.3-0.5 mm, spraying pressure 0.2-0.4 MPa, coating thickness controlled at 50-150 μm; Brush coating: Multiple coats, each coat is 20-50 μm thick; Dip coating: Coating time 30-120 seconds, control uniformity and then air dry; (3) Curing treatment: The coated metal substrate is subjected to curing treatment under the following process conditions: Curing temperature: 150-200°C; Curing time: 2-4 hours; Slowly increase the temperature to the target temperature to avoid coating cracking.