Stripping composite coating for synthesizing silicon carbide powder and preparation method of stripping composite coating

Abstract

The invention relates to the technical field of silicon carbide powder synthesis, in particular to a stripping composite coating for silicon carbide powder synthesis and a preparation method thereof.The preparation method comprises the steps that S1, the surface of a deposition matrix is coated with a resin solution, drying treatment is conducted, and a carbon layer is formed on the surface of the deposition matrix; s2, the step S1 is repeated for 0-3 times, a first carbon layer is formed on the surface of the deposition substrate, and the deposition substrate with the first carbon layer on the surface is obtained; s3, graphite powder, a first organic matter, a second organic matter and a solvent are mixed to form slurry, and the deposition substrate with the first carbon layer on the surface is coated with the slurry; and S4, low-temperature baking treatment and high-temperature baking treatment are conducted on the deposition matrix coated with the slurry, a second carbon layer is formed on the deposition matrix, and the deposition matrix with a stripping composite layer on the surface is obtained. The deposition substrate is protected through the first carbon layer; and the porous structure of the second carbon layer is beneficial to stagnation of the atmosphere, so that the early-stage deposition rate of the silicon carbide block can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide powder synthesis, in particular to a stripping composite coating for silicon carbide powder synthesis and a preparation method thereof. Background Art

[0002] As the intelligent interaction revolution driven by large-scale model technology continues to deepen, the field of augmented reality (AR) is experiencing unprecedented development opportunities. As the core hardware carrier of AR glasses, their optical display systems face three major technical challenges: how to achieve higher light efficiency in miniaturized lenses, how to effectively cope with the heat dissipation pressure brought by high-power laser projection, and how to solve the rainbow artifact problem caused by traditional diffraction waveguides. To address these industry pain points, high-purity, undoped silicon carbide (SiC) single crystal material has demonstrated breakthrough advantages: its naturally possessed ultra-wide bandgap (3.26eV) supports high-transmittance designs with a refractive index exceeding 2.66, far exceeding existing optical glass and resin materials; its excellent thermal conductivity (490W / m·K) is three times higher than that of copper, providing reliable heat dissipation for laser light sources; and its unique crystal structure eliminates diffraction dispersion at its source, achieving pure display across the entire visible spectrum. High-purity, undoped silicon carbide semiconductor-grade single crystal material not only perfectly meets the demands of AR glasses for ultimate optical performance, but is also expected to promote breakthroughs in mass production of lightweight holographic waveguide technology, providing a material foundation for the innovation of optical systems in the next generation of consumer-grade AR devices.

[0003] Currently, high-purity, undoped SiC is primarily produced using physical vapor transport (PVT). This involves sublimating high-purity, undoped SiC powder at high temperatures. Through temperature control, the atmosphere recrystallizes on a seed crystal, resulting in large-scale SiC single crystals. High-purity, undoped SiC powder is primarily produced using self-propagating and chemical vapor deposition (CVD). Due to its advantages in high purity and mass production, CVD holds great promise for producing silicon carbide powder. CVD produces silicon carbide powder by reacting methyltrichlorosilane and hydrogen at high temperatures, depositing it on a substrate, followed by crushing and removing the substrate. Specifically, Chinese patent number CN119118131 A discloses a method for synthesizing high-purity silicon carbide powder. This method effectively separates the silicon carbide bulk from the graphite substrate by adhering a layer of graphite paper to the graphite deposition substrate, thereby reducing the need for subsequent substrate removal. However, because graphite paper is expensive and fragile, achieving complete coverage of the deposition substrate with graphite paper significantly increases the production cost of SiC powder. Furthermore, the relatively smooth surface of graphite paper can affect the early deposition of SiC powder. Therefore, providing a low-cost and simple removal method is of great significance.

[0004] The present invention provides a stripping composite coating for synthesizing silicon carbide powder and a preparation method thereof, so as to solve the problems existing in the prior art in that graphite paper is used to cover a deposition substrate in the synthesis of high-purity silicon carbide powder, resulting in an increased production cost of silicon carbide powder, and the smooth surface of the graphite paper is not conducive to the early deposition of silicon carbide powder. Summary of the Invention

[0005] The purpose of the present invention is to provide a stripping composite coating for the synthesis of silicon carbide powder and a preparation method thereof, so as to solve the problems existing in the prior art in that the use of graphite paper to cover the deposition substrate in the synthesis of high-purity silicon carbide powder leads to increased production costs of silicon carbide powder, and the smooth surface of the graphite paper is not conducive to the early deposition of silicon carbide powder.

[0006] The technical solution of the present invention is: a method for preparing a stripping composite coating for synthesizing silicon carbide powder, comprising the following steps:

[0007] S1. Cleaning the surface of the deposition substrate, coating the surface of the deposition substrate with a resin solution, and drying the solution to form a carbon layer on the surface of the deposition substrate; the resin solution is an epoxy resin solution or a phenolic resin solution;

[0008] S2, repeating step S1 0-3 times to form a first carbon layer on the surface of the deposition substrate, thereby obtaining a deposition substrate having the first carbon layer on the surface;

[0009] S3. Calculating by mass percentage, mixing 30%-90% of graphite powder, 10-60% of the first organic matter, 0-10% of the second organic matter, and 0-20% of the solvent to form a slurry. Then, coating the formed slurry on the deposition substrate having the first carbon layer on the surface;

[0010] The first organic matter is any one or more of sugars, dimethyl carbonate, oxalic acid, tartaric acid, and cellulose; the second organic matter is any one or more of epoxy resin, phenolic resin, polyethylene glycol, and polyvinyl alcohol;

[0011] S4. The deposition substrate coated with the slurry is subjected to low-temperature baking treatment and high-temperature baking treatment in sequence. After the baking treatment is completed, a second carbon layer is formed on the first carbon layer to obtain a deposition substrate with a debonding composite layer on the surface.

[0012] Preferably, on the surface of the deposition substrate, the thickness of the first carbon layer is 0.01-0.5 mm; the thickness of the second carbon layer is 0.1-5 mm, and the porosity is 20-75%.

[0013] Preferably, the coating process of coating the resin solution on the surface of the deposition substrate is brushing or spraying;

[0014] The deposition substrate is made of graphite or metal; the metal is any one of tantalum, molybdenum and tungsten, or a metal compound.

[0015] Preferably, in step S1, the drying process is performed at a temperature of 50-300° C. and for a drying time of 10-100 min.

[0016] Preferably, in step S2, the particle size of the graphite powder is 10-200 μm; and the particle size of the first organic matter is 1-100 μm.

[0017] Preferably, the sugar is any one or more of sucrose, glucose, maltose, starch, fructose, and lactose;

[0018] The solvent is any one or more of pure water, ethanol, acetone, ethylene glycol, and toluene.

[0019] Preferably, in step S4, the low-temperature baking treatment is performed at a temperature of 50-100° C. and for a duration of 30-120 minutes;

[0020] The high-temperature baking treatment has a treatment temperature of 100-300° C. and a treatment time of 10-60 minutes.

[0021] The present invention also provides a stripping composite coating for synthesizing silicon carbide powder. The stripping composite coating for synthesizing silicon carbide powder is prepared by the above-mentioned preparation method.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] (1) The present invention provides a stripping composite coating for silicon carbide powder synthesis and a preparation method thereof. By preparing a stripping composite layer, namely a first carbon layer and a second carbon layer, on a deposition substrate, the first carbon layer with density is used to protect the deposition substrate, effectively avoiding the corrosion of the deposition substrate by corrosive atmospheres such as hydrogen chloride in the deposition chamber; the porous structure of the second carbon layer is conducive to the stagnation of the atmosphere, thereby increasing the early deposition rate of the silicon carbide powder; and the porous structure of the second carbon layer will make the mechanical properties of the composite layer poor, which is more conducive to the effective separation of the subsequent silicon carbide block and the deposition substrate; at the same time, the preparation method of the stripping composite layer is simple, easy to operate, and the raw material cost is also lower. Moreover, the stripping composite layers are all carbon layers, which will not affect the purity of the silicon carbide powder; it solves the problems existing in the prior art of using graphite paper to coat the deposition substrate in the synthesis of high-purity silicon carbide powder, which leads to increased production cost of silicon carbide powder, and the smooth surface of the graphite paper is not conducive to the early deposition of silicon carbide powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] Figure 1 This is a flow chart of the method for preparing the stripping composite coating of the present invention;

[0026] Figure 2 This is a morphology diagram of the second carbon layer prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be described in further detail below with reference to specific embodiments:

[0028] A method for preparing a stripping composite coating for synthesizing silicon carbide powder, such as Figure 1 As shown, it specifically includes the following steps: S1, wiping the deposition substrate with ethanol or methanol to clean the surface of the deposition substrate, and drying it after cleaning; then, applying a layer of resin solution on the surface of the deposition substrate by brushing or spraying, and placing the deposition substrate coated with the resin solution in an oven for drying. The drying temperature is 50-300°C, and the drying time is 10-100min. After the resin solution on the surface of the deposition substrate is sintered at high temperature, only C element remains, and a dense carbon layer is formed on the surface of the deposition substrate; wherein the resin solution is an epoxy resin solution or a phenolic resin solution; compared with the brushing process, the coating formed by applying the resin solution by the spraying process is smoother, denser, and has a more uniform thickness. Therefore, the spraying process is preferably used to apply the resin solution on the surface of the deposition substrate; the material of the deposition substrate can be selected as graphite, or it can be selected as a metal material, such as a single substance or metal compound of tantalum, tungsten, molybdenum, etc., preferably a metal carbide.

[0029] S2. Repeat step S1 0-3 times to form a first carbon layer on the surface of the deposition substrate, and obtain a deposition substrate with a first carbon layer on the surface; wherein the thickness of the first carbon layer is 0.01-0.5 mm; if the carbon layer formed on the surface of the deposition substrate is dense and its thickness reaches 0.05-0.5 mm after the above-mentioned step S1 treatment, step S1 does not need to be repeated. If the carbon layer formed on the surface of the deposition substrate is not dense or its thickness does not reach 0.01 mm after the above-mentioned step S1 treatment, step S1 needs to be repeated 1-3 times to form a dense carbon layer with a thickness of 0.01-0.5 mm on the surface of the deposition substrate as the first carbon layer.

[0030] S3. 30%-90% of graphite powder, 10-60% of a first organic matter, 0-10% of a second organic matter, and 0-20% of a solvent are mixed by mass percentage to form a slurry. Then, the slurry is applied to a deposition substrate having a first carbon layer on its surface, i.e., the formed first carbon layer, by a brush coating or spray coating process; wherein the content of the second organic matter and the solvent is not simultaneously zero; preferably, the slurry is applied to the deposition substrate having the first carbon layer on its surface by a brush coating process; The first organic matter is one or more of sugars, dimethyl carbonate, oxalic acid, tartaric acid, cellulose, etc.; the sugars are one or more of sucrose, glucose, maltose, starch, fructose, lactose, etc.; the second organic matter is one or more of epoxy resin, phenolic resin, polyethylene glycol, polyvinyl alcohol, etc.; the solvent is one or more of pure water, ethanol, acetone, ethylene glycol, toluene, etc.; and the particle size of the graphite powder needs to be controlled within the range of 10-200um; the first organic matter needs to be controlled within the range of 1-100um.

[0031] S4. Place the deposition substrate coated with the slurry into an oven and perform low-temperature baking treatment and high-temperature baking treatment in sequence; after low-temperature baking and high-temperature baking, only C element remains in the coated slurry, and a second carbon layer is formed on the deposition substrate, that is, a second carbon layer is formed on the first carbon layer, to obtain a deposition substrate with a dematerialized composite layer on the surface, that is, a deposition substrate having a first carbon layer and a second carbon layer in sequence from the inside to the outside; wherein, the treatment temperature of the low-temperature baking treatment is 50-100°C; the treatment time is 30-120min; the treatment temperature of the high-temperature baking treatment is 100-300°C; the treatment time is 10-60min.

[0032] Example 1

[0033] S1. Wiping the surface of the graphite rod with ethanol to achieve the effect of surface cleaning, and then coating the surface of the graphite rod with a layer of epoxy resin solution by a brush coating process; after the coating is completed, placing the graphite rod in an oven and drying it at 300° C.; after baking for 30 minutes, a dense first carbon layer is formed on the surface of the graphite rod, thereby obtaining a graphite rod having a first carbon layer on the surface; wherein the thickness of the first carbon layer is 0.05 mm;

[0034] S2. Graphite powder with an average particle size of 100 μm, sucrose with an average particle size of 20 μm, epoxy resin, and ethanol are mixed and uniformly mixed to form a slurry, wherein the slurry contains 40% graphite powder, 40% sucrose, 5% epoxy resin, and 15% ethanol by mass; the formed slurry is then coated on the graphite rod having the first carbon layer on the surface, i.e., coated on the first carbon layer;

[0035] S3. Place the graphite rod coated with the slurry in a high-temperature furnace, first perform a low-temperature baking treatment at 90°C, and after baking for 30 minutes, raise the temperature in the high-temperature furnace to 300°C and perform a high-temperature baking treatment on it. After baking for 30 minutes, a second carbon layer is formed on the first carbon layer, thereby obtaining a graphite rod having the first carbon layer and the second carbon layer on the surface in order from the inside to the outside; wherein the thickness of the second carbon layer is 1 mm and the porosity is 25%.

[0036] A graphite rod having a first carbon layer and a second carbon layer on its surface, sequentially from the inside to the outside, is installed inside a deposition chamber; methyltrichlorosilane, hydrogen, and argon are then introduced into the deposition chamber for deposition, so that silicon carbide powder is deposited on the graphite rod. The deposition temperature is controlled at 1100°C, the deposition pressure is 1 bar, and the deposition time is 24 hours. After the deposition is completed, the graphite rod is removed and crushed to obtain silicon carbide blocks and graphite blocks of a certain weight. The graphite fragments are removed to obtain silicon carbide blocks; wherein, the deposition rate of the silicon carbide block is 0.2 mm / h.

[0037] In the present application, the surface of the graphite rod is cleaned by wiping the surface with ethanol. In other embodiments, the surface of the deposition substrate may be cleaned by other methods, or the deposition substrate may not be surface treated.

[0038] Example 2

[0039] S1. Wipe the surface of the tantalum wire with ethanol to achieve the effect of cleaning the surface. Then, coat the surface of the tantalum wire with a phenolic resin solution by spraying. After the coating is completed, place the tantalum wire in an oven and dry it at 250° C. After baking for 30 minutes, a carbon layer is formed on the surface of the tantalum wire.

[0040] S2. Repeat step S1 once to form a dense first carbon layer on the surface of the tantalum filament, thereby obtaining a tantalum filament having a first carbon layer on the surface, wherein the thickness of the first carbon layer is 0.05 mm. Since the first carbon layer formed on the surface of the tantalum filament is dense, it can serve as a protective layer to prevent the tantalum itself from being corroded by the hydrogen chloride atmosphere in the environment during the deposition of the silicon carbide powder. At the same time, the flexibility of the tantalum filament can also be used to achieve the reuse of the deposition substrate.

[0041] S3, mixing graphite powder with an average particle size of 200 μm, sucrose with an average particle size of 20 μm, epoxy resin, and ethanol to form a slurry after uniform mixing, wherein the slurry contains 50% graphite powder, 30% sucrose, 5% epoxy resin, and 15% ethanol by mass percentage; then coating the formed slurry on the tantalum wire having the first carbon layer on the surface, that is, coating on the first carbon layer;

[0042] S4. Place the tantalum wire coated with the slurry into a high-temperature furnace, first perform a low-temperature baking treatment at 90°C, and after baking for 30 minutes, raise the temperature in the high-temperature furnace to 300°C and perform a high-temperature baking treatment on it. After baking for 30 minutes, a second carbon layer is formed on the first carbon layer, and a tantalum wire having a first carbon layer and a second carbon layer on the surface from the inside to the outside is obtained, wherein the thickness of the second carbon layer is 1 mm and the porosity is 45%; and, if Figure 2 As shown, the second carbon layer is relatively rough and has a large porosity on the surface.

[0043] A tantalum wire having a first carbon layer and a second carbon layer on its surface, sequentially from the inside to the outside, is installed inside a deposition chamber; methyltrichlorosilane, hydrogen, and argon are then introduced into the deposition chamber for deposition, so that silicon carbide powder is deposited on the graphite rod. The deposition temperature is controlled at 1100°C, the deposition pressure is 1 bar, and the deposition time is 24 hours. After the deposition is completed, the graphite rod is removed and crushed to obtain silicon carbide blocks and graphite blocks of a certain weight. The graphite fragments are removed to obtain silicon carbide blocks; wherein, the deposition rate of the silicon carbide block is 0.22 mm / h.

[0044] Example 3

[0045] S1. Wipe the surface of the tantalum wire with ethanol to achieve the effect of cleaning the surface. Then, apply a phenolic resin solution to the surface of the tantalum wire by brushing. After the coating is completed, place the tantalum wire in an oven and dry it at 200° C. After baking for 30 minutes, a carbon layer is formed on the surface of the tantalum wire.

[0046] S2, repeating step S1 twice to form a first carbon layer on the surface of the tantalum wire, thereby obtaining a tantalum wire having a first carbon layer on the surface, wherein the thickness of the first carbon layer is 0.1 mm;

[0047] S3, mixing graphite powder with an average particle size of 200 μm, dimethyl carbonate with an average particle size of 50 μm, epoxy resin, and ethanol to form a slurry after uniform mixing, wherein the slurry contains 50% graphite powder, 30% dimethyl carbonate, 5% epoxy resin, and 15% ethanol by mass percentage; then coating the formed slurry on the tantalum wire having the first carbon layer on the surface, that is, coating on the first carbon layer;

[0048] S4. The tantalum wire coated with the slurry is placed in a high-temperature furnace, and is first subjected to a low-temperature baking treatment at 90°C. After baking for 30 minutes, the temperature in the high-temperature furnace is raised to 300°C for a high-temperature baking treatment. After baking for 30 minutes, a second carbon layer is formed on the first carbon layer, and a tantalum wire having a first carbon layer and a second carbon layer on the surface from the inside to the outside is obtained, wherein the thickness of the second carbon layer is 1 mm and the porosity is 45%.

[0049] A tantalum wire having a first carbon layer and a second carbon layer on its surface, sequentially from the inside to the outside, is installed inside a deposition chamber; methyltrichlorosilane, hydrogen, and argon are then introduced into the deposition chamber for deposition, so that silicon carbide powder is deposited on the graphite rod. The deposition temperature is controlled at 1100°C, the deposition pressure is 1 bar, and the deposition time is 24 hours. After the deposition is completed, the graphite rod is removed and crushed to obtain silicon carbide blocks and graphite blocks of a certain weight. The graphite fragments are removed to obtain silicon carbide blocks; wherein, the deposition rate of the silicon carbide block is 0.22 mm / h.

[0050] Example 4

[0051] S1. A phenolic resin solution is coated on the tantalum wire by a spraying process. After coating, the tantalum wire is placed in an oven and dried at 250° C. After baking for 30 minutes, a dense first carbon layer is formed on the surface of the tantalum wire, thereby obtaining a tantalum wire having a first carbon layer on the surface, wherein the thickness of the first carbon layer is 0.05 mm.

[0052] A tantalum wire with a first carbon layer on its surface is installed inside a deposition chamber, and then methyltrichlorosilane, hydrogen, and argon are introduced into the deposition chamber for deposition, so that silicon carbide powder is deposited on the graphite rod. The deposition temperature is controlled at 1100°C, the deposition pressure is 1 bar, and the deposition time is 24 hours. After the deposition is completed, it is crushed to obtain silicon carbide blocks of a certain weight and a complete tantalum wire. The deposition rate of the silicon carbide block is 0.18 mm / h.

[0053] Comparative Example 1

[0054] A graphite rod was mounted in a deposition chamber. Methyltrichlorosilane, hydrogen, and argon were then introduced into the chamber to deposit silicon carbide powder onto the graphite rod. The deposition temperature was controlled at 1100°C, the pressure was 1 bar, and the deposition time was 24 hours. The deposition rate was 0.18 mm / h. After deposition, the rod was crushed to obtain a mixed block of silicon carbide and graphite blocks of a certain weight. The mixed block was placed in an oxidation furnace, which was then incinerated at 800°C for 5 hours with air flowing through it, to obtain a surface-oxidized silicon carbide block. The surface-oxidized silicon carbide block was then immersed in molten potassium hydroxide for 2 hours to remove the surface oxide layer. The deoxidized silicon carbide block was then rinsed in pure water to remove the potassium hydroxide on the surface. This was repeated five times, each rinse lasting 1 hour. The pure water was replaced after each rinse for the next rinse.

[0055] Comparing Example 1 with Comparative Example 1, it can be seen that coating the first carbon layer and the second carbon layer on the surface of the graphite rod can increase the initial deposition rate of the silicon carbide powder; and the stripping composite layers formed on the surface of the graphite rod are all carbon layers, which will not affect the purity of the silicon carbide; at the same time, since the second carbon layer on the graphite rod is a porous structure, its mechanical properties are poor, which is more conducive to the effective stripping of the silicon carbide block and the graphite rod in the subsequent processing process. Comparing Example 2 and Example 3 with Example 4, it can be seen that the initial deposition rate of the silicon carbide powder on the tantalum wire prepared in Example 2 and Example 3 is higher, and it can be seen that coating the stripping composite layer, i.e., the first carbon layer and the second carbon layer, on the deposition substrate can effectively increase the deposition rate of the silicon carbide block. This is because the second carbon layer formed on the deposition substrate is a porous structure with a high porosity, which is conducive to the stagnation of the atmosphere and thus increases the initial deposition rate. In addition, the stripping composite layer can also effectively alleviate the difference in thermal expansion coefficient between the silicon carbide block and the deposition substrate, especially when a deposition substrate made of a metal element or a metal compound is selected; specifically as shown in Examples 1-3, compared with graphite, the difference in thermal expansion coefficient between the tantalum wire and the silicon carbide block will be greater. Coating the stripping composite layer on the surface of the tantalum wire can effectively alleviate the difference in thermal expansion coefficient between the silicon carbide block and the tantalum wire, reduce the thermal stress between the silicon carbide block and the tantalum wire, and avoid the tantalum wire from breaking due to excessive thermal stress or the silicon carbide block falling off, which causes the tantalum wire to be unable to continue heating, causing the deposition process to end prematurely or causing damage to the deposition chamber, resulting in safety hazards, etc., thereby ensuring the production of silicon carbide powder and the service life of the inner wall material of the deposition chamber.

[0056] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they are not intended to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A method for preparing a stripping composite coating for synthesizing silicon carbide powder, characterized in that: The following steps are involved: S1. Cleaning the surface of the deposition substrate, coating the surface of the deposition substrate with a resin solution, and drying the solution to form a carbon layer on the surface of the deposition substrate; the resin solution is an epoxy resin solution or a phenolic resin solution; S2, repeating step S1 0-3 times to form a first carbon layer on the surface of the deposition substrate, thereby obtaining a deposition substrate having the first carbon layer on the surface; S3. Calculating by mass percentage, mixing 30%-90% of graphite powder, 10-60% of the first organic matter, 0-10% of the second organic matter, and 0-20% of the solvent to form a slurry. Then, coating the formed slurry on the deposition substrate having the first carbon layer on the surface; The first organic matter is any one or more of sugars, dimethyl carbonate, oxalic acid, tartaric acid, and cellulose; the second organic matter is any one or more of epoxy resin, phenolic resin, polyethylene glycol, and polyvinyl alcohol; S4. The deposition substrate coated with the slurry is subjected to low-temperature baking treatment and high-temperature baking treatment in sequence. After the baking treatment is completed, a second carbon layer is formed on the deposition substrate to obtain a deposition substrate with a debonding composite layer on the surface.

2. The method for preparing a stripping composite coating for synthesizing silicon carbide powder according to claim 1, characterized in that: On the surface of the deposition substrate, the thickness of the first carbon layer is 0.01-0.5 mm; the thickness of the second carbon layer is 0.1-5 mm, and the porosity is 20-75%.

3. The method for preparing a stripping composite coating for synthesizing silicon carbide powder according to claim 2, characterized in that: The coating process of coating the resin solution on the surface of the deposition substrate is brushing or spraying; The deposition substrate is made of graphite or metal; the metal is any one of tantalum, molybdenum and tungsten, or a metal compound.

4. The method for preparing a stripping composite coating for synthesizing silicon carbide powder according to claim 2, characterized in that: In step S1, the drying process is performed at a temperature of 50-300° C. and for a time of 10-100 minutes.

5. The method for preparing a stripping composite coating for synthesizing silicon carbide powder according to claim 2, characterized in that: In step S2, the particle size of the graphite powder is 10-200 μm; the particle size of the first organic matter is 1-100 μm.

6. The method for preparing a stripping composite coating for synthesizing silicon carbide powder according to claim 2, characterized in that: The sugar is any one or more of sucrose, glucose, maltose, starch, fructose, and lactose; The solvent is any one or more of pure water, ethanol, acetone, ethylene glycol, and toluene.

7. The method for preparing a stripping composite coating for synthesizing silicon carbide powder according to claim 2, characterized in that: In step S4, the low-temperature baking treatment is performed at a temperature of 50-100° C. and for a duration of 30-120 minutes. The high-temperature baking treatment has a treatment temperature of 100-300° C. and a treatment time of 10-60 minutes.

8. A stripping composite coating for silicon carbide powder synthesis, characterized in that: The preparation method is described in any one of claims 1 to 7.

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