Metal substrate with high-temperature oxidation-resistant coating and preparation method thereof

Abstract

The invention discloses a metal base material with a high-temperature anti-oxidation coating and a preparation method of the metal base material. The metal base material is used for solving the problems that a coating prepared through an existing preparation technology is poor in binding force with a base body, uneven in coating thickness and the like. The metal base material comprises a metal matrix and an anti-oxidation coating coated on the surface of the metal matrix; the antioxidant coating is prepared by mixing graphite powder and organic resin in a mass ratio of 1: (2-3), and dissolving the mixture in an organic solvent to prepare slurry containing the graphite powder; and coating the surface of a metal matrix with the slurry containing the graphite powder, and preparing by combining a high-temperature powder burying process. According to the preparation method, a composite process of slurry pre-coating and high-temperature powder burying is adopted, phenolic resin and graphite powder are selected as core carbon sources for supply, and finally, a uniform and compact carbide coating is prepared on the surface of a metal matrix, so that firm combination of the coating and the metal matrix is realized, and meanwhile, the high-temperature stability, wear resistance and corrosion resistance of the coating are improved.

Description

Technical Field

[0001] This invention relates to a method for preparing a high-temperature antioxidant coating, specifically to a metal substrate with a high-temperature antioxidant coating and its preparation method. Background Technology

[0002] Refractory metals and their alloys, such as tungsten, molybdenum, tantalum, and niobium, have been widely used in extreme service conditions, including hot-end components of aero-engines and linings of high-end industrial furnaces, due to their high melting points, high strength, excellent thermal and electrical conductivity, and superior resistance to acid and alkali corrosion. However, these materials have a strong affinity for oxygen and are prone to rapid oxidation at high temperatures, leading to structural component failure and a significant decline in their high-temperature performance. Specifically, tantalum and niobium exhibit severe pulverization at temperatures exceeding 600°C; over time, a large amount of loose and porous Nb₂O₅ and Ta₂O₅ oxide layers form on the material surface, severely damaging the overall performance and service life of the material. Molybdenum and tungsten, at temperatures above 750°C, experience a sharp decline in performance and a drastically reduced lifespan due to the formation of volatile oxides such as MoO₃ and WO₃. Therefore, high-temperature oxidation remains one of the key bottlenecks restricting the engineering application of refractory metals and their alloys as high-temperature structural materials.

[0003] High-performance high-temperature protective coatings are crucial for ensuring the service performance of refractory metals. Among these, silicide coatings are the most widely used due to their mature technology and good protective stability. However, with technological advancements, traditional single-coating systems such as silicide coatings, aluminide coatings, inert oxide ceramic coatings, alloy coatings, and precious metal coatings are no longer sufficient to meet the requirements of refractory metals, including ultra-high service temperatures, thermal shock resistance, ablation resistance (thermal erosion resistance), high-temperature self-healing, and long service life. Therefore, designing and developing novel high-temperature protective coatings suitable for refractory metals has become essential to meeting this national strategic need.

[0004] Existing coating preparation technologies mainly include chemical vapor deposition (CVD), physical vapor deposition (PVD), slurry sintering, and embedding / infiltration methods. (1) CVD method: Chemical vapor deposition is one of the most mature carbide coating preparation processes in the industrial field. Specifically, a refractory metal substrate is first placed in a high-temperature reaction chamber, and then a gaseous precursor containing carbon and metal elements is introduced. The gaseous precursor undergoes gas-phase decomposition and chemical reaction under high-temperature conditions, and finally a dense coating is deposited on the surface of the refractory metal substrate. The advantage of this preparation process is that the coating has high density and strong adhesion to the substrate. However, the deposition temperature is relatively high, which can easily lead to grain growth in the substrate material, thereby affecting its mechanical properties. In addition, the ability of this preparation process to uniformly deposit on complex-shaped substrates needs to be improved.

[0005] (2) PVD method: Physical vapor deposition is a method that uses physical means (such as sputtering, evaporation, ion plating, etc.) to bombard and strip atoms or ions from a carbide target, causing them to deposit onto the surface of a refractory metal substrate to form a carbide coating. The core features of this method are low deposition temperature (200~500℃), which can effectively avoid the influence of high temperature on the substrate properties; good coating uniformity and high controllability of thickness, making it suitable for preparing thin and dense protective coatings. However, the coating prepared by this method has weak adhesion to the substrate, and it is difficult to prepare thick coatings.

[0006] (3) Slurry sintering method: Carbide powder, binder, solvent, etc. are mixed and prepared into a uniform slurry. The slurry is then coated onto the surface of the refractory metal substrate by coating, spraying, etc. After drying and degreasing, it is sintered at high temperature under vacuum or protective atmosphere to finally form a carbide coating that meets the requirements of composition and thickness. The significant advantages of this method are simple process, low cost, flexible coating structure design, and adaptability to irregular components. However, the sintering process is prone to generating pores, resulting in low coating density and insufficient bonding strength with the substrate, which makes it easy to peel off under thermal cycling or mechanical load.

[0007] (4) Embedding and Infiltration Method: The embedding and infiltration method (i.e., high-temperature powder embedding process) is currently the most commonly used in-situ reaction method for preparing refractory metal carbide coatings. Its core process is as follows: the refractory metal substrate is embedded in an embedding material composed of carbon powder, carbide powder, activator, etc., sealed, and placed in a sintering furnace for high-temperature sintering under a protective atmosphere such as vacuum or argon. Under high-temperature conditions, carbon atoms in the embedding material migrate to the surface of the substrate through diffusion and react in-situ with the metal atoms of the substrate to form a carbide coating that is metallurgically bonded to the substrate. This method has low preparation cost, simple operation, and high coating deposition efficiency; the coating and the substrate form a metallurgical bond with high bonding strength and excellent thermal shock resistance, making it suitable for large-scale industrial production. However, the uniformity of the coating composition and thickness formed by this method is difficult to control, and its coverage ability for hidden parts such as the internal cavities of complex components is weak. Summary of the Invention

[0008] The purpose of this invention is to provide a metal substrate with a high-temperature anti-oxidation coating and its preparation method, which solves the technical problems of poor adhesion between the coating and the substrate and uneven coating thickness obtained by existing high-temperature protective coating preparation processes.

[0009] To achieve the above objectives, the technical solution provided by this invention is as follows: A metal substrate with a high-temperature anti-oxidation coating, characterized by: Includes a metal substrate and an anti-oxidation coating covering the surface of the metal substrate; The antioxidant coating is prepared by mixing graphite powder and organic resin in a mass ratio of 1:2~3 and dissolving them in an organic solvent to form a slurry containing graphite powder; then coating the slurry containing graphite powder onto the surface of a metal substrate, combined with a high-temperature powder embedding process.

[0010] Furthermore, the thickness of the antioxidant coating is 300~500μm.

[0011] Furthermore, the metal matrix is ​​a refractory metal, selected from tungsten, molybdenum, tantalum or niobium; The organic resin is selected from one of phenolic resin, epoxy resin, and furan resin; The organic solvent is selected from one or more of ethanol, acetone, and xylene.

[0012] Meanwhile, the present invention also provides a method for preparing a metal substrate with a high-temperature anti-oxidation coating, comprising the following steps: Step 1: Slurry preparation and coating 1.1 Prepare the metal substrate and pretreat it according to the preset process requirements; 1.2 Weigh graphite powder and organic resin according to the specified ratio, mix them, dissolve them in an organic solvent, and stir until completely dissolved to obtain a slurry containing graphite powder; the mass ratio of graphite powder to organic resin is 1:2~3. 1.3 The slurry obtained in step 1.2 is uniformly coated onto the surface of the pretreated metal substrate in step 1.1 to form a metal substrate covered with a carbon film; Step 2: High-temperature powder embedding treatment 2.1 Place the carbon-coated metal substrate in a crucible containing carbon powder and bury it with carbon powder, then seal the crucible. 2.2 Place the sealed crucible into a vacuum furnace and heat it at a uniform rate. After it reaches the preset temperature, keep it at that temperature to initially synthesize a carbide coating on the surface of the metal substrate. 2.3 Based on step 2.2, a second heating treatment is performed, followed by cooling to room temperature to obtain a metal substrate with a high-temperature anti-oxidation coating.

[0013] Further, in step 1.2, the organic resin is selected from one of phenolic resin, epoxy resin, and furan resin; the organic solvent is selected from one or more of ethanol, acetone, and xylene.

[0014] Further, step 1.3 specifically involves uniformly coating the slurry obtained in step 1.2 onto the surface of the pretreated metal substrate in step 1.1, applying it 2 to 3 times, and draining it for 20 to 40 minutes after each application, thereby forming a metal substrate covered with a carbon film.

[0015] Furthermore, in step 2.1, when the metal substrate covered with carbon film is placed inside the crucible, the metal substrate is located at the center of the crucible; the sealed crucible refers to placing the crucible lid on the crucible and sealing the joint between the crucible lid and the crucible with the slurry described in step 1.2.

[0016] Furthermore, in step 2.2, the uniform heating rate refers to heating at a rate of 3~5℃ / min; the preset temperature is 800℃~1000℃, and the holding time is 1~3h.

[0017] Furthermore, in step 2.3, the secondary heating process refers to heating to 1200-1500℃ and then holding at that temperature for 10-15 hours.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the metal substrate with high-temperature anti-oxidation coating provided by the present invention, the anti-oxidation coating is supplied with organic resin and graphite powder as the core carbon source, and finally a uniform and dense carbide coating is prepared on the surface of the metal substrate, so as to achieve a firm bond between the coating and the metal substrate, and at the same time improve the high-temperature stability, wear resistance and corrosion resistance of the coating.

[0019] 2. The metal substrate with high-temperature anti-oxidation coating provided by the present invention is applicable to refractory metals such as tungsten, molybdenum, tantalum or niobium, and can form a uniform coating with a thickness of 300~500μm.

[0020] 3. The method for preparing a metal substrate with a high-temperature anti-oxidation coating provided by the present invention achieves precise control over the composition and thickness of the carbide coating through slurry pre-coating, thereby ensuring the uniformity of the coating.

[0021] 4. The method for preparing a metal substrate with a high-temperature anti-oxidation coating provided by the present invention selects organic resin and graphite powder as the core carbon source. On the one hand, organic resin can improve the formability and adhesion of the pre-coated layer, ensure the uniformity of the coating, and at high temperature, organic resin can carbonize to form a tight interface of "substrate-carbon film", providing an initial carbon source for subsequent reactions and helping to block oxygen diffusion. On the other hand, graphite powder provides sufficient carbon source for the formation of carbide coating, ensuring the stable generation of carbide phase in the coating, and can further optimize the coating density and anti-oxidation performance in the high-temperature powder embedding stage, strengthening the bonding strength between the coating and the metal substrate.

[0022] 5. The method for preparing a metal substrate with a high-temperature antioxidant coating provided by the present invention uses organic resin and graphite powder as carbon sources, eliminating the need for additional gaseous carbon supply, reducing system energy consumption, and thus reducing preparation costs. Attached Figure Description

[0023] Figure 1This is a schematic flowchart illustrating an embodiment of the method for preparing a metal substrate with a high-temperature anti-oxidation coating according to the present invention.

[0024] Figure 2 This is a cross-sectional morphology diagram of the tungsten carbide coating on a metal tungsten sheet prepared by Example 2 of the preparation method of the metal substrate with high-temperature anti-oxidation coating of the present invention after high-temperature calcination. Figure 3 This is a surface morphology image of the tungsten carbide coating on a metal substrate with a high-temperature anti-oxidation coating prepared in Example 2 of the preparation method of the present invention after high-temperature calcination. Detailed Implementation

[0025] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0026] Example 1 This embodiment provides a metal substrate with a high-temperature anti-oxidation coating, comprising a metal substrate and an anti-oxidation coating covering the surface of the metal substrate. The anti-oxidation coating is prepared by mixing graphite powder and organic resin in a mass ratio of 1:2 to 3, dissolving the mixture in an organic solvent to form a slurry containing graphite powder; then, the slurry containing graphite powder is coated onto the surface of the metal substrate using a high-temperature powder embedding process. The organic resin is selected from phenolic resin, epoxy resin, and furan resin; the organic solvent is selected from one or more of ethanol, acetone, and xylene.

[0027] This embodiment employs a composite process of "slurry pre-coating + high-temperature powder embedding" and selects phenolic resin and graphite powder as the core carbon source to ultimately prepare a uniform and dense carbide coating with a thickness of 300~500μm on the surface of a refractory metal. This achieves a strong bond between the coating and the metal substrate, while also improving the coating's high-temperature stability, wear resistance, and corrosion resistance.

[0028] In this embodiment, the metal substrate can be selected from refractory metals such as tungsten, molybdenum, tantalum, or niobium. The composition and thickness of the carbide coating can be precisely controlled by pre-coating with slurry. At the same time, the bonding strength between the coating and the refractory metal substrate is strengthened by high-temperature powder embedding process, and finally a uniform, dense, and firmly bonded carbide coating is obtained.

[0029] Taking an M20 molybdenum bolt as an example, this embodiment provides a method for preparing a molybdenum bolt with a high-temperature anti-oxidation coating, including the following steps: Step 1: Slurry preparation and coating 1.1 Prepare a sample of molybdenum bolt and pre-treat it according to the preset process requirements (grind the surface and clean and dry). The total length L of the pre-treated molybdenum bolt sample is 30 mm, and the bolt length B is 18 mm.

[0030] 1.2 Mix 80g of phenolic resin and 40g of graphite powder and dissolve them in 200ml of anhydrous ethanol until completely dissolved to obtain a uniform suspension, i.e., slurry.

[0031] In this embodiment, phenolic resin is used as the initial carbon source, colloidal graphite powder as the reinforcing phase, and anhydrous ethanol as the dispersion medium. On the one hand, phenolic resin can improve the formability and adhesion of the pre-coated layer, ensure the uniformity of the coating, and under high temperature conditions, phenolic resin can carbonize to form a tight "substrate-carbon film" interface, providing an initial carbon source for subsequent reactions and helping to block oxygen diffusion. On the other hand, graphite powder provides sufficient carbon source for the formation of carbide coatings, ensuring the stable formation of carbide phases in the coating, and at the same time, the high-temperature powder embedding stage can further optimize the coating density and oxidation resistance.

[0032] 1.3 The slurry obtained in step 1.2 is uniformly coated onto the surface of the pretreated molybdenum bolt sample in step 1.1. Generally, it is coated three times, and after each coating, it is allowed to drain for 20 minutes. During coating, it is necessary to spread it evenly to avoid slurry dripping or local accumulation, so as to ensure that a dense carbon film is formed and tightly adhered to the surface of the molybdenum bolt sample, forming a tight interface between the substrate and the carbon film, which provides the initial carbon source for subsequent reactions. At this time, the molybdenum bolt covered with carbon film is formed.

[0033] Step 2: High-temperature powder embedding treatment 2.1 Use a covered crucible and fill it with carbon powder. Then place the carbon-coated molybdenum bolts inside the crucible, with both ends 20 mm away from the crucible wall. Then bury them with carbon powder and seal the crucible.

[0034] In this embodiment, the powder embedding height is 25mm (ensuring the bolts are completely covered). After embedding, the crucible lid is placed on top, and the joint between the crucible lid and the crucible is sealed with the aforementioned slurry to achieve the airtightness of the reaction system and prevent interference from the external atmosphere. The proportion of phenolic resin in the sealing slurry can also be adjusted to a viscosity of 500 mPa·s to ensure the viscosity of the slurry.

[0035] 2.2 The sealed crucible was placed in a vacuum furnace and heated at a rate of 3℃ / min. After reaching 800℃, it was kept at that temperature for 2 hours to initially synthesize a carbonized coating on the surface of the molybdenum bolt.

[0036] During this process, the toner slowly releases activated carbon, while the pre-coated carbon film gradually breaks down the activated carbon atoms, and the dual carbon sources are adsorbed onto the surface of the metal molybdenum bolt. The activated carbon atoms and the surface atoms of the metal molybdenum bolt undergo a slight diffusion reaction to generate a thin layer of low-valence carbides, forming a tight "substrate-carbon film" interface, thus avoiding stress concentration at the interface caused by high-temperature reaction.

[0037] 2.3 Based on step 2.2, the temperature is further increased to 1200℃ and held for 10 hours, and then naturally cooled to room temperature to obtain a molybdenum metal bolt with a molybdenum carbide coating. The molybdenum carbide coating has excellent density and is firmly bonded to the molybdenum metal bolt.

[0038] During this process, the atoms on the surface of the molybdenum bolt react fully with carbon to transform into molybdenum carbide. As the reaction progresses, molybdenum carbide grains are generated and stacked, forming a dense molybdenum carbide coating. Simultaneously, the thickness of the molybdenum carbide coating increases, strengthening the bond between the coating and the molybdenum bolt. The resulting molybdenum carbide (MoC) possesses high melting point, high hardness, excellent high-temperature stability, and corrosion resistance, effectively solving the problem of high-temperature oxidation of refractory metals while improving the coating's wear and corrosion resistance.

[0039] The extreme working condition stability of the molybdenum bolt with molybdenum carbide coating prepared in this embodiment was verified. Specifically, the sample (the molybdenum bolt with molybdenum carbide coating) was placed in a crucible, and then the crucible was placed in a single crystal silicon furnace. After calcination at 1500°C for 24 hours, the sample was taken out and its coating cross-sectional morphology was observed. It was found that there were no defects such as cracking, peeling, or bulging on the surface of the molybdenum carbide coating. After observing its surface morphology and combining its surface energy spectrum information, it can be seen that the surface composition of the molybdenum carbide coating did not change significantly compared with that before calcination.

[0040] Example 2 Taking tungsten sheet as an example, this embodiment provides a method for preparing tungsten sheet with a high-temperature anti-oxidation coating, including the following steps: Step 1: Slurry preparation and coating 1.1 Prepare a tungsten sheet sample and pre-treat it according to the preset process requirements (grind the surface and clean and dry). The size of the tungsten sheet sample after pre-treatment is 50mm*50mm*2mm, and the weight at this time (i.e. the initial weight of the tungsten sheet) is 95.8g.

[0041] 1.2 Mix 60g of phenolic resin and 30g of graphite powder and dissolve them in 200ml of anhydrous ethanol until completely dissolved to obtain a uniform suspension, i.e., slurry.

[0042] 1.3 The slurry obtained in step 1.2 is uniformly coated onto the surface of the tungsten sheet sample after the pretreatment in step 1.1. Generally, it is coated three times, and after each coating, it is drained for 20 minutes. During coating, it is necessary to spread it evenly to avoid slurry dripping or local accumulation, so as to ensure that a dense carbon film is formed and tightly adhered to the surface of the tungsten sheet sample, forming a tight interface of "substrate-carbon film", which provides the initial carbon source for subsequent reactions. At this time, a tungsten sheet covered with carbon film is formed.

[0043] Step 2: High-temperature powder embedding treatment 2.1 Use a covered crucible and fill it with carbon powder. Then place a tungsten sheet covered with carbon film inside the crucible, with its circumferential distance from the crucible wall 20 mm. Then bury it with carbon powder and seal the crucible.

[0044] In this embodiment, the powder embedding height is 15mm (ensuring the tungsten sheet is completely covered). After embedding, the crucible lid is placed on top, and the joint between the lid and the crucible is sealed with the aforementioned slurry to achieve a tight seal of the reaction system and prevent interference from the external atmosphere. The proportion of phenolic resin in the sealing slurry can also be adjusted to a viscosity of 500 mPa•s to ensure the viscosity of the slurry.

[0045] 2.2 The sealed crucible was placed in a vacuum furnace and heated at a rate of 3℃ / min. After reaching 800℃, it was held for 2 hours to initially synthesize a carbide coating on the surface of the tungsten sheet.

[0046] During this process, the toner slowly releases activated carbon, while the pre-coated carbon film gradually breaks down the activated carbon atoms, and the dual carbon sources are adsorbed onto the surface of the tungsten sheet; the activated carbon atoms and the atoms on the surface of the tungsten sheet undergo a slight diffusion reaction to generate a thin layer of low-valence carbides, forming a tight "substrate-carbon film" interface, avoiding stress concentration at the interface caused by high-temperature reaction.

[0047] 2.3 Based on step 2.2, continue heating to 1200℃ and hold for 10 hours, then allow to cool naturally to room temperature to obtain a tungsten metal sheet with a tungsten carbide coating. The tungsten carbide coating has a density >98% and is firmly bonded to the tungsten metal sheet.

[0048] During this process, the atoms on the surface of the tungsten sheet react fully with carbon to transform into tungsten carbide. As the reaction progresses, tungsten carbide grains are generated and stacked, forming a dense tungsten carbide coating. Simultaneously, the thickness of the tungsten carbide coating increases, strengthening the bond between the coating and the tungsten sheet. The resulting tungsten carbide (WC) possesses high melting point, high hardness, excellent high-temperature stability, and corrosion resistance, effectively solving the problem of high-temperature oxidation of refractory metals while improving the wear resistance and corrosion resistance of the coating.

[0049] The extreme working condition stability of the tungsten metal sheet with tungsten carbide coating prepared in this embodiment was verified. Specifically, the sample (the tungsten metal sheet with tungsten carbide coating) was placed in a crucible, and then the crucible was placed in a single-crystal silicon furnace. After calcination at 1500°C for 24 hours, the sample was taken out and its coating cross-sectional morphology was observed. It was found that there were no defects such as cracking, peeling, or bulging on the surface of the tungsten carbide coating. Figure 2 As shown); its surface morphology was observed ( Figure 3 As shown in the figure, its surface morphology uniformity is relatively good.

[0050] Table 1 shows the surface energy spectrum information of the tungsten metal sheet with tungsten carbide coating prepared in this embodiment before and after continuous calcination at 1500℃ for 24 hours.

[0051] Table 1. Surface energy spectrum information of tungsten carbide coating before and after high-temperature calcination of tungsten sheets. As shown in Table 1, the surface composition of the tungsten sheet with tungsten carbide coating did not change significantly before and after calcination, which indicates its high-temperature stability.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A metal substrate with a high-temperature anti-oxidation coating, characterized in that: Includes a metal substrate and an anti-oxidation coating covering the surface of the metal substrate; The antioxidant coating is prepared by mixing graphite powder and organic resin in a mass ratio of 1:2~3 and dissolving them in an organic solvent to form a slurry containing graphite powder; then coating the slurry containing graphite powder onto the surface of a metal substrate, combined with a high-temperature powder embedding process.

2. The metal substrate with a high-temperature anti-oxidation coating according to claim 1, characterized in that: The thickness of the antioxidant coating is 300~500μm.

3. The metal substrate with a high-temperature anti-oxidation coating according to claim 1, characterized in that: The metal matrix is ​​a refractory metal, selected from tungsten, molybdenum, tantalum or niobium; The organic resin is selected from one of phenolic resin, epoxy resin, and furan resin; The organic solvent is selected from one or more of ethanol, acetone, and xylene.

4. A method for preparing a metal substrate with a high-temperature antioxidant coating as described in claim 1, characterized in that, Includes the following steps: Step 1: Slurry preparation and coating 1.1 Prepare the metal substrate and pretreat it according to the preset process requirements; 1.2 Weigh graphite powder and organic resin according to the specified ratio, mix them, dissolve them in an organic solvent, and stir until completely dissolved to obtain a slurry containing graphite powder; the mass ratio of graphite powder to organic resin is 1:2~3. 1.3 The slurry obtained in step 1.2 is uniformly coated onto the surface of the pretreated metal substrate in step 1.1 to form a metal substrate covered with a carbon film; Step 2: High-temperature powder embedding treatment 2.1 Place the carbon-coated metal substrate in a crucible containing carbon powder and bury it with carbon powder, then seal the crucible. 2.2 Place the sealed crucible into a vacuum furnace and heat it at a uniform rate. After it reaches the preset temperature, keep it at that temperature to initially synthesize a carbide coating on the surface of the metal substrate. 2.3 Based on step 2.2, a second heating treatment is performed, followed by cooling to room temperature to obtain a metal substrate with a high-temperature anti-oxidation coating.

5. The method for preparing a metal substrate with a high-temperature anti-oxidation coating according to claim 4, characterized in that: In step 1.2, the organic resin is selected from one of phenolic resin, epoxy resin, and furan resin; the organic solvent is selected from one or more of ethanol, acetone, and xylene.

6. The method for preparing a metal substrate with a high-temperature antioxidant coating according to claim 4, characterized in that: Step 1.3 specifically involves uniformly coating the slurry obtained in step 1.2 onto the surface of the pretreated metal substrate in step 1.1, applying it 2 to 3 times, and draining it for 20 to 40 minutes after each application, thereby forming a metal substrate covered with a carbon film.

7. The method for preparing a metal substrate with a high-temperature antioxidant coating according to claim 4, characterized in that: In step 2.1, when the metal substrate covered with carbon film is placed in the crucible, the metal substrate is located at the center of the crucible; the sealed crucible refers to covering the crucible with a crucible lid and sealing the joint between the crucible lid and the crucible with the slurry described in step 1.

2.

8. The method for preparing a metal substrate with a high-temperature anti-oxidation coating according to claim 4, characterized in that: In step 2.2, the uniform heating rate refers to heating at a rate of 3~5℃ / min; the preset temperature is 800℃~1000℃, and the holding time is 1~3h.

9. The method for preparing a metal substrate with a high-temperature anti-oxidation coating according to claim 8, characterized in that: In step 2.3, the secondary heating process refers to heating to 1200-1500℃ and then holding at that temperature for 10-15 hours.

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