A method for preparing a pyrolytic carbon interface coating using a hybrid precursor

Abstract

The present application relates to a kind of preparation methods for preparing pyrolytic carbon interface coating using mixed precursor, belong to silicon carbide fiber reinforced silicon carbide composite interface coating preparation technical field, more specifically, a kind of preparation method for preparing pyrolytic carbon interface coating using methane and ethanol mixed precursor on the surface of silicon carbide fiber deposition.By controlling deposition process parameters, the dense uniform, thickness and texture controllable pyrolytic carbon interface layer is prepared, the problems of slow deposition rate, processing process is not easy to control, pyrolytic carbon texture form cannot be effectively controlled in the preparation process of pyrolytic carbon interface layer in the prior art are solved.

Description

Technical Field

[0001] This invention relates to silicon carbide fiber reinforced silicon carbide (SiC). f This invention relates to the field of SiC composite material interface coating preparation technology, specifically to a method for preparing a pyrolytic carbon interface coating using a mixed precursor. Background Technology

[0002] Silicon carbide fiber reinforced silicon carbide (SiC) f SiC composite materials possess high strength, high modulus, low density, excellent mechanical properties, high temperature resistance, and good oxidation resistance. Their application in hot-end components of aero-engines can significantly increase operating temperatures, simplify cooling structures, and thus effectively improve the thrust-to-weight ratio of aero-engines. Therefore, SiC is an ideal candidate material for hot-end components of next-generation high-performance aero-engines. f / SiC composites have high toughness and damage tolerance, and the interface layer acts as a SiC f In SiC composites, key components that regulate mechanical behavior play a crucial role in load transfer and crack deflection. Among them, the pyrolytic carbon interfacial layer, with its typical layered structure, not only forms a weak interfacial bond between SiC fibers and the SiC matrix, promoting crack deflection and fiber pull-out, but its graphite microcrystals can also repair surface defects in SiC fibers, making it an ideal material for SiC fiber interfacial coatings.

[0003] Currently, pyrolytic carbon structures can be classified into four categories based on their external morphology: isotropic laminar (ISO), regenerative laminar (ReL), smooth laminar (SL), and rough laminar (RL). The regenerative laminar layer is an intermediate structure between the isotropic and smooth laminar layers. Rough laminar carbon (i.e., high-texture pyrolytic carbon) exhibits high lamellar orientation, smooth fracture surfaces, only a few fine cracks between lamellars, high density, and a high degree of graphitization. The degree of graphitization is a key factor determining the graphitization potential of SiC. f One of the most important structural parameters for the thermophysical, tribological, and mechanical properties of SiC composites is the presence of a high-texture, rough-textured pyrolytic carbon layer. Existing research has found that composites with high-texture, rough-textured pyrolytic carbon layers exhibit the best mechanical properties; those with isotropic pyrolytic carbon layers have the lowest density and the worst mechanical properties; while low-texture pyrolytic carbon is prone to thermal stress microcracks.

[0004] In existing technologies, the preparation of pyrolytic carbon with different textures often uses small alkane molecules such as methane, propane, or ethylene, or alcohols such as ethanol, as a single precursor. When methane is used as a common alkane precursor, the gas-phase reaction process is difficult to control, resulting in a narrow range of process parameters for obtaining high-texture pyrolytic carbon. When ethanol is used as a single precursor, its low diffusion coefficient easily leads to the formation of harmful products during deposition. Chinese patent CN101439981A discloses a method for preparing carbon / carbon composite materials, using ethanol-modified methane as a precursor, which only reduces the carbon content of the precursor and does not solve the deposition rate related to the pyrolytic carbon interface layer. Chinese patent CN113004051A discloses a SiC... f The interfacial layer structure and preparation method of SiC composite fuel cladding were developed. Ethanol was placed in a deposition furnace and heated, followed by the introduction of methane gas. A (PyC / SiC)2 composite interfacial layer was designed, solving the SiC... f The method addresses the issues of interfacial layer stability and service life in SiC composites, but it is complex and cannot be used to adjust the density and texture type of the pyrolytic carbon interfacial layer.

[0005] Therefore, it is necessary to investigate a method for preparing pyrolytic carbon interface coatings to fabricate highly textured pyrolytic carbon structures and further improve the SiC quality. f Toughness of / SiC composite materials. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method for preparing a pyrolytic carbon interface coating using a mixed precursor. By controlling the deposition process parameters, a dense, uniform pyrolytic carbon interface layer with controllable thickness and texture can be prepared. This solves the problems of slow deposition rate, difficulty in controlling the processing, and inability to effectively control the texture morphology of pyrolytic carbon in the preparation of pyrolytic carbon interface layers in the prior art.

[0007] The present invention aims to provide a method for preparing a pyrolytic carbon interfacial coating using a mixed precursor, comprising the following steps:

[0008] S1. Place the SiC fiber bundle in the corresponding mold, and then place the mold in a chemical vapor deposition furnace to deposit a pyrolytic carbon coating.

[0009] Preferably, the process parameters for the pyrolytic carbon coating deposition in step S1 are as follows: the deposition furnace is evacuated to a vacuum degree of less than 100 Pa, nitrogen gas is introduced, the deposition pressure is 2000-7000 Pa, the furnace temperature is raised to 1000-1200℃, and held for 2-4 hours; the nitrogen gas flow rate is 800-1000 sccm; and the furnace temperature rise rate is 5-10℃ / min.

[0010] Preferably, in step S1, the mold is placed in the chemical vapor deposition furnace at a distance of 2-18 cm from the air inlet.

[0011] Furthermore, the mold is placed 2 cm away from the air inlet inside the chemical vapor deposition furnace.

[0012] The present invention adjusts the distance between the sample and the gas inlet in the chemical vapor deposition furnace, thereby changing the reaction time between the sample and the precursor gas, and consequently altering the residence time of the precursor gas on the SiC fiber surface. With constant reaction temperature, reaction pressure, and total gas flow rate, a smaller reaction zone volume and a shorter residence time result in the acquisition of high-texture pyrolytic carbon.

[0013] S2. Once the furnace temperature in step S1 has risen to a certain level, methane and anhydrous ethanol are introduced into the furnace, and the deposition pressure is 2000-7000 Pa to begin deposition.

[0014] Preferably, the method of introducing anhydrous ethanol in step S2 is as follows: nitrogen is used as the carrier gas and introduced into the furnace by bubbling; the ratio of the carrier gas flow rate to the methane flow rate is 1-5:2-5; the volume fraction of methane is 99.00-99.99%; the purity of anhydrous ethanol is 99.50-99.80%; and the deposition time is 2-4 hours.

[0015] Furthermore, the ratio of the carrier gas flow rate to the methane flow rate is 1:1; the methane flow rate is 200-500 sccm, and the carrier gas flow rate is 200-500 sccm.

[0016] The technical solution of this invention achieves a transformation in the texture morphology of the pyrolytic carbon interface layer from a rough pyrolytic carbon layer to a smooth pyrolytic carbon layer by adjusting the flow ratio of methane and ethanol precursors.

[0017] The technical solution of this invention uses methane and anhydrous ethanol as a mixed precursor, which solves the problems of slow deposition rate and difficulty in controlling the texture morphology of pyrolytic carbon when using methane as a single precursor, and the problems of low diffusion coefficient, difficulty in controlling the experimental process, and easy generation of harmful byproducts when using ethanol as a single precursor. It can prepare a high-texture pyrolytic carbon interface coating with excellent mechanical properties within a wide range of process parameters.

[0018] S3. End the deposition process, stop the introduction of methane and anhydrous ethanol, continue to introduce nitrogen as a protective gas, adjust the furnace pressure to be consistent with the deposition pressure described in step S2, and stop heating after the furnace temperature is reduced to 700-900℃. Allow the chemical vapor deposition furnace to cool naturally to room temperature to obtain a pyrolytic carbon interface coating.

[0019] Preferably, the nitrogen flow rate in step S3 is 800-1000 sccm, and the cooling rate to reduce the temperature to 700-900℃ is 5-10℃ / min.

[0020] The technical solution of this invention systematically regulates the texture morphology of the pyrolytic carbon interface layer by precisely controlling the reaction temperature, reaction pressure, reaction time, and the ratio of methane and ethanol precursors, thereby improving the stability of the preparation process and the designability of the microstructure of the interface coating.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) This invention uses methane and ethanol as a mixed precursor, which can overcome the problems of slow deposition rate and difficulty in controlling the texture morphology of pyrolytic carbon when using methane as a single precursor, and the problems of low diffusion coefficient, easy generation of harmful products such as soot and carbon black, and difficulty in controlling the experimental process when using ethanol as a single precursor. It can prepare a high-texture pyrolytic carbon interface coating with excellent mechanical properties within a wide range of process parameters.

[0023] (2) By precisely controlling the reaction temperature, reaction pressure, reaction time, and the ratio of methane and ethanol precursors, this invention can systematically control the texture morphology of the pyrolytic carbon interface layer, thereby improving the stability of the preparation process and the designability of the microstructure of the interface coating.

[0024] (3) The present invention uses a mixed precursor of two carbon sources, which can increase the yield of pyrolytic carbon and improve the production efficiency of interface coating. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] Figure 1 This is a schematic diagram of the experimental gas path used in this invention;

[0027] Figure 2 This is a schematic diagram of the full width at half maximum (FWHM) of the Raman spectrum defect peaks of the pyrolytic carbon interface layer prepared in embodiments (1-1) to (1-9) of the present invention.

[0028] Figure 3 This is a schematic diagram of the cross-sectional scanning electron microscope images of the pyrolytic carbon interface layer prepared in embodiments (1-1) to (1-9) of the present invention.

[0029] Figure 4 This is a schematic diagram showing the variation of the full width at half maximum (FWHM) of the Raman spectra of the pyrolytic carbon interface layers prepared in embodiments (2-1) to (2-5), (3-1) to (3-5), and (4-1) to (4-5) of the present invention under different deposition pressures and deposition temperatures;

[0030] Figure 5 This is a schematic diagram illustrating the thickness variation of the pyrolytic carbon interface layer prepared in embodiments (2-2) to (2-4), (3-2) to (3-4), and (4-2) to (4-4) of the present invention under different deposition pressures and deposition temperatures.

[0031] Figure 6 This is the Raman spectrum of the pyrolytic carbon interface layer prepared in Example 5 of the present invention;

[0032] Figure 7 This is a schematic diagram of the surface scanning electron microscope image of the pyrolytic carbon interface layer prepared in Example 6 of the present invention.

[0033] Explanation of icon numbers:

[0034] 1-Methane mass flow meter; 2-Nitrogen mass flow meter; 3-Nitrogen mass flow meter Detailed Implementation

[0035] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0036] A specific embodiment of the present invention, such as Figure 1-7 A SiC f The interface coating of silicon carbide / silicon carbide composite material and its preparation method are as follows:

[0037] Example 1-1

[0038] S1. SiC fiber bundles are wound around a graphite frame to obtain a SiC fiber preform. The SiC fiber preform is placed in a graphite mold, and then the graphite mold is placed in a chemical vapor deposition furnace for pyrolytic carbon coating deposition. The distance between the SiC fiber preform and the gas inlet of the chemical vapor deposition furnace is adjusted to 2 cm. The furnace is evacuated to a pressure of 100 Pa at room temperature. Nitrogen gas is introduced as a protective gas at a flow rate of 1000 sccm. The furnace pressure is adjusted to 2000 Pa using a vacuum pump. The furnace temperature is raised from room temperature to 1150 °C at a heating rate of 10 °C / min and held for 2 hours.

[0039] S2. Once the furnace temperature reaches the heat preservation stage in step S1, methane is introduced into the furnace at a flow rate of 200 sccm. At the same time, ethanol is introduced into the chemical vapor deposition furnace by bubbling using nitrogen as the carrier gas. The carrier gas flow rate is 200 sccm, the deposition pressure is 2000 Pa, and the deposition time is 2 hours.

[0040] S3. After deposition for 2 hours, stop the introduction of methane and ethanol, and continue to introduce nitrogen gas as a protective gas at a flow rate of 1000 sccm. Adjust the pressure inside the furnace to 2000 Pa, and reduce the temperature to 900°C at a cooling rate of 10°C / min to make it consistent with the vacuum level described in step S1. Allow it to cool naturally to room temperature to obtain the pyrolytic carbon interface coating.

[0041] The difference between Examples (1-2) to (1-9) and Example 1-1 is that: in step S1, the distance between the SiC fiber preform and the gas inlet of the chemical vapor deposition furnace is adjusted to 4, 6, 8, 10, 12, 14, 16, and 18 cm, respectively.

[0042] Examples (1-1) to (1-9) obtained pyrolytic carbon interface layers with different thicknesses and textures by adjusting the distance between the reaction zone and the gas inlet of the deposition furnace. Figure 2 The full width at half maximum (FWHM) of the Raman spectrum defect peaks of the pyrolytic carbon interface layers prepared in Examples (1-1) to (1-9) is given, wherein the wavenumber of the FWHM of the Raman spectrum defect peaks is less than 90 cm⁻¹. -1 The material is pyrolytic carbon with a high-texture, rough layer; the Raman spectrum shows a defect peak with a full width at half maximum (FWHM) of 90–140 cm⁻¹. -1 The layer between them is pyrolytic carbon with a smooth texture; the Raman spectrum shows a defect peak with a full width at half maximum (FWHM) greater than 140 cm⁻¹. -1 The pyrolytic carbon in the low-texture regenerated layer is shown in the figure. Electron microscopy was performed on the cross-sections of the pyrolytic carbon interface layers with different texture morphologies, and the results are as follows: Figure 3 As shown, Figure 3 (a) shows the cross-sectional morphology of the interface of the highly textured rough layer of pyrolytic carbon, where the layered structure of the pyrolytic carbon is clearly visible, with high degree of lamellar orientation. Figure 3 (b) shows the cross-sectional morphology of the pyrolytic carbon interface in the medium-textured smooth layer, with low lamellar orientation. Figure 3 (c) shows the cross-sectional morphology of the pyrolytic carbon interface in the low-texture regenerated layer, which is a disordered graphite structure. It can be seen that as the distance between the SiC fiber preform and the gas inlet of the deposition furnace increases, the texture morphology of the pyrolytic carbon interface layer changes from rough pyrolytic carbon layer → smooth pyrolytic carbon layer → regenerated pyrolytic carbon layer → smooth pyrolytic carbon layer, that is, the texture degree shows a trend of first decreasing and then increasing.

[0043] Example 2-1

[0044] S1. SiC fiber bundles are wound around a graphite frame to obtain a SiC fiber preform. The SiC fiber preform is placed in a graphite mold, and then the graphite mold is placed in a chemical vapor deposition furnace for pyrolytic carbon coating deposition. The distance between the SiC fiber preform and the gas inlet of the chemical vapor deposition furnace is adjusted to 2 cm. The furnace is evacuated to a pressure of 100 Pa at room temperature. Nitrogen gas is introduced as a protective gas at a flow rate of 1000 sccm. The furnace pressure is adjusted to 2000 Pa using a vacuum pump. The furnace temperature is raised from room temperature to 1000℃ at a heating rate of 10℃ / min and held for 2 hours.

[0045] S2. Once the furnace temperature reaches the heat preservation stage in step S1, methane is introduced into the furnace at a flow rate of 200 sccm. At the same time, ethanol is introduced into the chemical vapor deposition furnace by bubbling using nitrogen as the carrier gas. The carrier gas flow rate is 200 sccm, the deposition pressure is 2000 Pa, and the deposition time is 2 hours.

[0046] S3. After deposition for 2 hours, stop the introduction of methane and ethanol, and continue to introduce nitrogen gas as a protective gas at a flow rate of 1000 sccm. Use a vacuum pump to adjust the pressure inside the furnace to 2000 Pa, and reduce the temperature to 900°C at a cooling rate of 10°C / min to make it consistent with the vacuum level described in step S1. Allow it to cool naturally to room temperature to obtain the pyrolytic carbon interface coating.

[0047] The difference between Examples (2-2) to (2-5) and Example (2-1) is that in step S1, the temperature inside the deposition furnace is increased to 1050, 1100, 1150 and 1200°C, respectively.

[0048] The difference between Examples (3-1) to (3-5) and Examples (2-1) to (2-5) is that: in step S1, the pressure inside the deposition furnace is 5000 Pa.

[0049] The difference between Examples (4-1) to (4-5) and Examples (2-1) to (2-5) is that: in step S1, the pressure inside the deposition furnace is 7000 Pa.

[0050] This embodiment prepares pyrolytic carbon interface layers with different thicknesses and textures by adjusting the deposition temperature and deposition pressure. Figure 4 The full width at half maximum (FWHM) of the Raman spectrum defect peaks of the pyrolytic carbon interface layers prepared in Examples (2-1) to (4-5) is as follows: Figure 4 As shown, under the same deposition pressure, the texture of the pyrolytic carbon interface layer first increases and then decreases with increasing deposition temperature. However, at the same deposition temperature, the texture of the pyrolytic carbon interface layer decreases with increasing deposition pressure. Through Examples (2-1) to (4-5), deposition temperatures of 1100℃ and 1150℃ and a deposition pressure of 2 kPa were obtained for preparing high-textured pyrolytic carbon interface layers.

[0051] The thickness changes of the pyrolytic carbon interface layer at 1050, 1100, and 1150 °C were obtained at 2000, 5000, and 7000 Pa, respectively. Figure 5 As shown, under the same furnace pressure conditions, the pyrolytic carbon deposition rate increases with increasing deposition temperature.

[0052] Example 5

[0053] The difference between Example 5 and Example (1-1) is as follows: S2, when the furnace temperature in step S1 reaches the heat preservation stage, methane is introduced into the furnace at a flow rate of 200 sccm, and at the same time, ethanol is introduced into the chemical vapor deposition furnace by bubbling using nitrogen as the carrier gas. The carrier gas flow rate is 100 sccm, the deposition pressure is 2000 Pa, and the deposition time is 2 hours.

[0054] Figure 6 The Raman spectra of the pyrolytic carbon interface layers prepared under different precursor ratios at a deposition pressure of 2000 Pa are shown. (a) is the Raman spectrum of the rough layer of pyrolytic carbon, corresponding to a methane to carrier gas flow ratio of 1:1, and (b) is the Raman spectrum of the smooth layer of pyrolytic carbon, corresponding to a methane to carrier gas flow ratio of 2:1. It can be seen that as the ratio of methane to ethanol precursor flow increases, the texture morphology of the pyrolytic carbon interface layer changes from a rough layer to a smooth layer.

[0055] Example 6-1

[0056] The difference between Example (6-1) and Example (1-1) is that: in step S1, the furnace temperature is raised from room temperature to 1100℃ at a heating rate of 10℃ / min and held for 2 hours.

[0057] Example 6-2

[0058] The difference between Example (6-2) and Example (6-1) is that: in step S1, the furnace temperature is raised from room temperature to 1100℃ at a heating rate of 10℃ / min and held for 4 hours.

[0059] This embodiment prepared pyrolytic carbon interface layers with different thicknesses and textures by adjusting the reaction time. With increasing deposition time, the texture of the pyrolytic carbon interface layers transformed from a rough layer of pyrolytic carbon to a regenerated layer of pyrolytic carbon. The surfaces of the pyrolytic carbon interface layers with different textures were scanned by electron microscopy, and the results are as follows: Figure 7 As shown. Figure 7 (a) is the surface morphology of the high-texture rough layer pyrolytic carbon coating. The high-texture rough layer pyrolytic carbon mainly undergoes a continuous surface growth mechanism, thus forming a smooth pyrolytic carbon morphology. Figure 7 (b) shows the surface morphology of the low-texture regenerated pyrolytic carbon coating. The low-texture rough layer of pyrolytic carbon mainly undergoes gas-phase nucleation mechanism, resulting in the formation of particulate macromolecules on the surface of the pyrolytic carbon coating.

[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a pyrolytic carbon interfacial coating using a mixed precursor, characterized in that, The specific steps include the following: S1. SiC fiber bundles are wound around a graphite frame to obtain a SiC fiber preform. The SiC fiber preform is placed in a graphite mold, and then the graphite mold is placed in a chemical vapor deposition furnace for pyrolytic carbon coating deposition. The distance between the SiC fiber preform and the gas inlet of the chemical vapor deposition furnace is adjusted to 2 cm. The furnace is evacuated to a pressure of 100 Pa at room temperature. Nitrogen gas is introduced as a protective gas at a flow rate of 1000 sccm. The furnace pressure is adjusted to 2000 Pa using a vacuum pump. The furnace temperature is raised from room temperature to 1050 °C at a heating rate of 10 °C / min and held for 2 hours. It also includes: a gas supply system for the mixed precursor, which includes a mixing tank, a methane gas supply module, a nitrogen gas supply module, and an anhydrous ethanol gas supply module; It also includes: methane mass flow meters and nitrogen mass flow meters; S2. Once the furnace temperature reaches the holding stage in step S1, methane is introduced into the furnace at a flow rate of 200 sccm. At the same time, anhydrous ethanol is introduced into the chemical vapor deposition furnace by bubbling using nitrogen as the carrier gas. The carrier gas flow rate is 200 sccm, the deposition pressure is 2000 Pa, and the deposition time is 2 hours. S3. After deposition, stop the introduction of methane and anhydrous ethanol, and continue to introduce nitrogen gas as a protective gas at a flow rate of 1000 sccm. Use a vacuum pump to adjust the pressure inside the furnace to 2000 Pa, and cool the temperature down to 900℃ at a cooling rate of 10℃ / min to make it consistent with the vacuum level in step S1. Allow it to cool naturally to room temperature to obtain the pyrolytic carbon interface coating.

2. A method for preparing a pyrolytic carbon interfacial coating using a mixed precursor, characterized in that, The specific steps include the following: S1. SiC fiber bundles are wound around a graphite frame to obtain a SiC fiber preform. The SiC fiber preform is placed in a graphite mold, and then the graphite mold is placed in a chemical vapor deposition furnace for pyrolytic carbon coating deposition. The distance between the SiC fiber preform and the gas inlet of the chemical vapor deposition furnace is adjusted to 2 cm. The furnace is evacuated to a pressure of 100 Pa at room temperature. Nitrogen gas is introduced as a protective gas at a flow rate of 1000 sccm. The furnace pressure is adjusted to 2000 Pa using a vacuum pump. The furnace temperature is raised from room temperature to 1100℃ at a heating rate of 10℃ / min and held for 2 hours. It also includes: a gas supply system for the mixed precursor, which includes a mixing tank, a methane gas supply module, a nitrogen gas supply module, and an anhydrous ethanol gas supply module; It also includes: methane mass flow meters and nitrogen mass flow meters; S2. Once the furnace temperature reaches the holding stage in step S1, methane is introduced into the furnace at a flow rate of 200 sccm. At the same time, anhydrous ethanol is introduced into the chemical vapor deposition furnace by bubbling using nitrogen as the carrier gas. The carrier gas flow rate is 200 sccm, the deposition pressure is 2000 Pa, and the deposition time is 2 hours. S3. After deposition, stop the introduction of methane and anhydrous ethanol, and continue to introduce nitrogen gas as a protective gas at a flow rate of 1000 sccm. Use a vacuum pump to adjust the pressure inside the furnace to 2000 Pa, and cool the temperature down to 900℃ at a cooling rate of 10℃ / min to make it consistent with the vacuum level in step S1. Allow it to cool naturally to room temperature to obtain the pyrolytic carbon interface coating.

3. A method for preparing a pyrolytic carbon interfacial coating using a mixed precursor, characterized in that, The specific steps include the following: S1. SiC fiber bundles are wound around a graphite frame to obtain a SiC fiber preform. The SiC fiber preform is placed in a graphite mold, and then the graphite mold is placed in a chemical vapor deposition furnace for pyrolytic carbon coating deposition. The distance between the SiC fiber preform and the gas inlet of the chemical vapor deposition furnace is adjusted to 2 cm. The furnace is evacuated to a pressure of 100 Pa at room temperature. Nitrogen gas is introduced as a protective gas at a flow rate of 1000 sccm. The furnace pressure is adjusted to 2000 Pa using a vacuum pump. The furnace temperature is raised from room temperature to 1150 °C at a heating rate of 10 °C / min and held for 2 hours. It also includes: a gas supply system for the mixed precursor, which includes a mixing tank, a methane gas supply module, a nitrogen gas supply module, and an anhydrous ethanol gas supply module; It also includes: methane mass flow meters and nitrogen mass flow meters; S2. Once the furnace temperature reaches the holding stage in step S1, methane is introduced into the furnace at a flow rate of 200 sccm. At the same time, anhydrous ethanol is introduced into the chemical vapor deposition furnace by bubbling using nitrogen as the carrier gas. The carrier gas flow rate is 200 sccm, the deposition pressure is 2000 Pa, and the deposition time is 2 hours. S3. After deposition, stop the introduction of methane and anhydrous ethanol, and continue to introduce nitrogen gas as a protective gas at a flow rate of 1000 sccm. Use a vacuum pump to adjust the pressure inside the furnace to 2000 Pa, and cool the temperature down to 900℃ at a cooling rate of 10℃ / min to make it consistent with the vacuum level in step S1. Allow it to cool naturally to room temperature to obtain the pyrolytic carbon interface coating.

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