Process for depositing silicon carbide coating on surface of graphite piece

Abstract

The invention relates to a process for depositing a silicon carbide coating on the surface of a graphite piece, which is characterized by comprising the following steps: S1, placing the cleaned graphite piece in a deposition chamber, closing the chamber, and vacuumizing; s2, depositing a transition layer on the surface of the graphite piece, S3, introducing double precursor gases, hydrogen and argon into the deposition chamber, and depositing on the surface of the transition layer to obtain a silicon carbide layer; s4, stopping introducing the gas, carrying out heat preservation for a period of time, then bombarding the surface by using inert gas plasma for etching, and continuously carrying out heat preservation to obtain a product; the double precursor gas comprises methyl trichlorosilane and methylsilane. The method has the effect of improving the bonding strength of the silicon carbide coating and the surface of the graphite piece.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of silicon carbide, in particular to a process for depositing a silicon carbide coating on the surface of a graphite piece. BACKGROUND

[0002] In the MOCVD epitaxy process of high-end manufacturing such as semiconductors, photovoltaics, LEDs, etc., graphite is the preferred substrate for the carrier disc because of its high-temperature stability, close thermal expansion coefficient to silicon substrate, and excellent thermal conductivity. However, graphite is easily oxidized at high temperatures, and its porous structure adsorbs reaction byproducts, which can cause a decrease in the precision of the carrier disc and particle contamination of the epitaxial wafer. Therefore, a SiC coating needs to be deposited on the surface to protect it.

[0003] The existing SiC coating has the problem of insufficient adhesion between the coating and the graphite. The thermal expansion coefficient difference between the silicon carbide coating and the graphite piece substrate is significant, and periodic thermal stress occurs at the interface during thermal cycling, causing cracks in the coating. Moreover, the interface is mostly physically bonded, without chemical bond support, and can be peeled off by mechanical vibration or air flow impact. SUMMARY

[0004] In order to improve the adhesion between the silicon carbide coating and the surface of the graphite piece, the present application provides a process for depositing a silicon carbide coating on the surface of a graphite piece.

[0005] The process for depositing a silicon carbide coating on the surface of a graphite piece provided by the present application adopts the following technical solution: A process for depositing a silicon carbide coating on the surface of a graphite piece includes the following steps: S1, placing the cleaned graphite piece in a deposition chamber, closing the chamber, and performing vacuum pumping; S2, depositing a transition layer on the surface of the graphite piece, S3, introducing double precursor gas, hydrogen, and argon into the deposition chamber to deposit a silicon carbide layer on the surface of the transition layer; S4, stopping the introduction of gas, performing etching on the surface using inert gas plasma after a certain period of heat preservation, and obtaining the product after further heat preservation; The double precursor gas includes methyltrichlorosilane and methylsilane.

[0006] By adopting the above technical solution, a transition deposition layer is provided on the surface of the graphite piece, so that the silicon carbide coating and the surface of the graphite piece can be chemically bonded, thereby improving the bonding performance between the surface of the graphite piece and the silicon carbide. At the same time, methyltrichlorosilane and methylsilane are used as the double precursor gas for the silicon carbide coating, and the silicon carbide layer deposited on the surface of the transition layer is more dense and uniform. Finally, etching is performed on the surface using inert gas plasma, which can eliminate particles with weak interfacial bonding, thereby reducing the occurrence of cracks or peeling in the prepared product.

[0007] As preferred, the mass ratio between the methyltrichlorosilane and the methylsilane is 1:(0.4-1.6).

[0008] By adopting the above technical solution, the uniformity and stability of the deposited silicon carbide layer can be effectively improved by preferably setting the mass ratio between the methyltrichlorosilane and the methylsilane within the above range. During the deposition process, the methylsilane is first decomposed and rapidly nucleates on the surface of the transition layer, and then the methyltrichlorosilane is supplemented to stably and efficiently grow. The obtained silicon carbide coating has good stability and heat resistance, improves the overall mechanical strength of the system, effectively improves the interfacial bonding force of the prepared product, and improves the stability, reducing the peeling phenomenon.

[0009] As preferred, the mass ratio between the double precursor gas and the argon is 1:(8-14).

[0010] By adopting the above technical solution, the uniformity and stability of the deposited silicon carbide layer can be effectively improved by preferably setting the mass ratio between the methyltrichlorosilane and the methylsilane within the above range. During the deposition process, the methylsilane is first decomposed and rapidly nucleates on the surface of the transition layer, and then the methyltrichlorosilane is supplemented to stably and efficiently grow. The obtained silicon carbide coating has good stability and heat resistance, improves the overall mechanical strength of the system, effectively improves the interfacial bonding force of the prepared product, and improves the stability, reducing the peeling phenomenon.

[0011] As preferred, the silicon carbide layer deposition includes a first deposition stage and a second deposition stage, the first deposition stage temperature is 800-900℃, and the time is 15-25min, the second deposition stage temperature is 950-1150℃, and the time is 120-180min.

[0012] By adopting the above technical solution, the uniformity and stability of the deposited silicon carbide layer can be effectively improved by preferably setting the mass ratio between the methyltrichlorosilane and the methylsilane within the above range. During the deposition process, the methylsilane is first decomposed and rapidly nucleates on the surface of the transition layer, and then the methyltrichlorosilane is supplemented to stably and efficiently grow. The obtained silicon carbide coating has good stability and heat resistance, improves the overall mechanical strength of the system, effectively improves the interfacial bonding force of the prepared product, and improves the stability, reducing the peeling phenomenon.

[0013] As preferred, the transition layer includes a metal titanium layer and a connecting layer, the metal titanium layer is attached to the surface of the graphite piece, the connecting layer is deposited on the surface of the metal titanium layer, and the metal titanium layer is deposited by a physical vapor deposition method.

[0014] By adopting the technical scheme, firstly, the metal titanium layer is deposited on the surface of the graphite piece, and in the subsequent deposition and heat treatment process, the metal titanium and the carbon atoms on the surface of the graphite piece form Ti-C covalent bonds, so that the graphite and the metal titanium layer are tightly combined and fixed, at the same time, the metal titanium layer has good ductility, which can relieve the thermal stress difference in the subsequent coating deposition process, reduce the phenomenon of interface peeling, and the subsequent connecting layer and the metal titanium layer can also be tightly combined, so that the transition layer and the graphite piece surface and the silicon carbide layer are more stably combined.

[0015] Preferably, the connecting layer comprises a carbon nitride layer, and a precursor of the carbon nitride layer comprises melamine and acetylene.

[0016] By adopting the technical scheme, melamine and acetylene are used as precursors to prepare the connecting layer, i.e. the carbon nitride layer, N of the carbon nitride layer and Ti of the metal titanium layer form Ti-N covalent bonds, at the same time, C of the carbon nitride layer and Si of the silicon carbide layer form Si-N covalent bonds, so that continuous chemical bonds are formed between the metal titanium layer, the connecting layer and the silicon carbide layer, thereby greatly improving the bonding capacity between the graphite piece, the connecting layer and the silicon carbide layer.

[0017] Preferably, the deposition of the carbon nitride layer adopts the following steps: The deposition chamber is heated, argon is introduced to make the pressure of the deposition chamber 350-550 Pa, melamine is heated and mixed with argon, introduced into the deposition chamber, and acetylene gas is introduced into the deposition chamber at the same time, and the carbon nitride layer is deposited.

[0018] By adopting the technical scheme, argon is used as a carrier to transport melamine, and acetylene is introduced at the same time, so that melamine and acetylene are uniformly distributed in the deposition chamber, and then the decomposition of melamine and the cleavage groups of acetylene generate a carbon nitride system on the surface of the system, thereby connecting the transition layer and the silicon carbide layer deposited by subsequent gas phase deposition.

[0019] Preferably, the mass ratio between the melamine, acetylene and argon is 1:(1.1-1.9):30.

[0020] By adopting the technical scheme, the mass ratio between the melamine, acetylene and argon is preferably within the above range, so that the prepared carbon nitride layer is more stable, uniformly distributed and has fewer defects, thereby improving the overall mechanical strength and connection strength of the system.

[0021] Preferably, the deposition temperature during deposition is 570-620℃, and the deposition time is 90-110min.

[0022] By adopting the technical scheme, the deposition temperature and time are preferably within the above range, so that the reaction in the deposition process is more complete, and the obtained carbon nitride layer has good stability.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: 1. The method of combining transition layer, double precursor silicon carbide deposition and plasma etching post-processing improves the poor bonding performance of silicon carbide deposited directly on the surface of graphite parts; the transition layer serves as a connecting bridge between the graphite parts and the silicon carbide, thereby improving the overall bonding performance of the system; the double precursor gases methyltrichlorosilane and methylsilane synergistically improve the growth of silicon carbide; inert gas plasma etching reduces weakly bonded phases, further strengthening the interface adhesion of the silicon carbide layer and the transition layer; 2. By using a metal titanium layer and a carbon nitride connecting layer as a transition layer, stable Ti-C and Ti-N covalent bonds are formed in situ at the interface, not only providing rigid support for the titanium layer, but also having the stress buffering ability of the carbon nitride layer, which further improves and enhances the interface bonding performance of the system, and improves the overall stability of the system; 3. The temperature and time parameters during deposition are preferably selected to make the deposition between the layers more stable, thereby improving the stability of the prepared product. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in conjunction with the examples: Raw material description: all raw materials in the examples can be obtained through market purchase; Example 1 Step of depositing silicon carbide coating on the surface of graphite parts: S1, immerse the graphite parts in ethanol and ultrasonically clean for 15 minutes, then take out and dry to obtain cleaned graphite parts, and place the cleaned graphite parts in a deposition chamber, close the chamber and vacuumize; S2, deposit a transition layer on the surface of the graphite parts: Introduce high-purity argon gas into the chamber, and maintain the working pressure at 0.8 Pa, use high-purity titanium as the target material with a purity of more than 99.99%, and apply a sputtering power of 3 W / cm 2 Perform sputter deposition for 45 min to form a metal titanium layer on the surface of the graphite parts, and the thickness of the metal titanium layer is 80 nm; argon gas as a protective gas, and then the temperature of the deposition chamber is raised to 570°C at a temperature raising rate of 10°C / min, the argon gas flow rate is adjusted, the pressure in the deposition chamber is stabilized at 350 Pa, the melamine powder is heated to 360°C to sublimate the melamine, the argon gas is introduced to carry the melamine vapor into the deposition chamber, and at the same time, the acetylene gas is introduced into the deposition chamber, the mass ratio among the melamine, the acetylene and the argon gas in the deposition chamber is controlled to be 1:1.1:30; and the deposition is performed for 110 min to deposit a carbon nitride layer on the surface of the metal titanium layer of the graphite piece, and the thickness of the carbon nitride layer is 200 nm; S3, methyltrichlorosilane and methylsilane are used as the dual precursor gas, the dual precursor gas, hydrogen and argon are introduced into the deposition chamber, the mass ratio between the methyltrichlorosilane and the methylsilane in the dual precursor gas is 1:0.4, the mass ratio between the dual precursor gas and the argon is 1:8, the mass ratio between the dual precursor gas and the hydrogen is 1:8, the pressure in the deposition chamber is controlled to be 2 kPa, the deposition is divided into a first deposition stage and a second deposition stage, in the first deposition stage, the temperature of the deposition chamber is raised to 800°C, the deposition time is 25 min, and the first deposition stage is completed; then the deposition chamber is raised to 950°C at a rate of 5°C / min, and the gas introduction is maintained, the deposition is performed for 180 min, and finally a silicon carbide layer is obtained on the surface of the carbon nitride layer of the transition layer, and the thickness of the silicon carbide layer is 5 μm; S4, the introduction of the dual precursor gas and the hydrogen is stopped, the argon gas is kept flowing, the temperature is kept at 1000°C for 30 min, then the pressure in the deposition chamber is adjusted to 120 Pa, the plasma generator is started, the silicon carbide coating surface is treated by bombardment at a power of 500 W for 100 s, the temperature is kept at 800°C for 20 min, then the argon atmosphere is maintained, the deposition chamber is cooled to 200°C, the argon gas is continuously filled to normal pressure, and the deposition chamber is opened, and the graphite piece product with the silicon carbide coating on the surface is obtained after cooling.

[0025] Example 2 The graphite piece surface deposition silicon carbide coating step: S1, the graphite piece is immersed in ethanol and ultrasonically cleaned for 15 minutes, taken out and dried to obtain a cleaned graphite piece, and the cleaned graphite piece is placed in a deposition chamber, the chamber is closed, and vacuumized; S2, depositing a transition layer on the surface of the graphite piece: High-purity argon gas is introduced into the chamber, and the working pressure is kept at 0.8 Pa, high-purity titanium is used as the target material, the purity is above 99.99%, and a sputtering power of 3 W / cm 2 Sputtering deposition is performed, and a metal titanium layer is formed on the surface of the graphite piece, and the thickness of the metal titanium layer is 80 nm; argon gas as a protective gas, and then the temperature of the deposition chamber is raised to 620℃ at a temperature raising rate of 10℃ / min, the argon gas flow rate is adjusted, the pressure in the deposition chamber is stabilized at 550Pa, the melamine powder is heated to 360℃ to sublimate the melamine, the argon gas is introduced to carry the melamine vapor into the deposition chamber, and at the same time, the acetylene gas is introduced into the deposition chamber, the mass ratio among the melamine, the acetylene and the argon gas in the deposition chamber is controlled to be 1:1.9:30; the deposition is performed for 90min to deposit a carbon nitride layer on the surface of the metal titanium layer of the graphite piece, and the thickness of the carbon nitride layer is 200nm; S3, methyltrichlorosilane and methylsilane are used as the dual precursor gas, the dual precursor gas, hydrogen gas and argon gas are introduced into the deposition chamber, the mass ratio between the methyltrichlorosilane and the methylsilane in the dual precursor gas is 1:1.6, the mass ratio between the dual precursor gas and the argon gas is 1:14, the mass ratio between the dual precursor gas and the hydrogen gas is 1:8, the pressure in the deposition chamber is controlled to be 2kPa, the deposition is divided into a first deposition stage and a second deposition stage, in the first deposition stage, the temperature of the deposition chamber is raised to 900℃, the deposition time is 15min, and the first deposition stage is completed; then the deposition chamber is raised to 1150℃ at a rate of 5℃ / min, and the gas introduction is maintained, the deposition is performed for 120min, and finally a silicon carbide layer is obtained on the surface of the carbon nitride layer of the transition layer, and the thickness of the silicon carbide layer is 5μm; S4, the introduction of the dual precursor gas and the hydrogen gas is stopped, the flow of the argon gas is maintained, the temperature is kept at 1000℃ for 30min, then the pressure in the deposition chamber is adjusted to 120Pa, the plasma generator is started, the silicon carbide coating surface is bombarded at a power of 500W for 100s, the temperature is kept at 800℃ for 20min, then the argon gas atmosphere is maintained, the deposition chamber is cooled to 200℃, the argon gas is continuously filled to normal pressure, and the deposition chamber is opened, and the graphite piece product with the silicon carbide coating deposited on the surface is obtained after cooling.

[0026] Example 3 Graphite piece surface deposition silicon carbide coating steps: S1, the graphite piece is immersed in ethanol and ultrasonically cleaned for 15min, taken out and dried to obtain a cleaned graphite piece, and the cleaned graphite piece is placed in a deposition chamber, the chamber is closed, and vacuumized; S2, depositing a transition layer on the surface of the graphite piece: High-purity argon gas is introduced into the chamber, and the working pressure is kept at 0.8Pa, high-purity titanium is used as the target material, the purity is above 99.99%, and a sputtering power of 3W / cm 2 Sputtering deposition is performed, and a metal titanium layer is formed on the surface of the graphite piece, and the thickness of the metal titanium layer is 80nm; The temperature of the deposition chamber is raised to 595℃ at a temperature raising rate of 10℃ / min, the argon gas flow rate is adjusted, the pressure in the deposition chamber is stabilized at 450Pa, the melamine powder is heated to 360℃ to sublimate the melamine, the argon gas is introduced to carry the melamine vapor into the deposition chamber, the acetylene gas is introduced into the deposition chamber, and the mass ratio among the melamine, the acetylene and the argon gas in the deposition chamber is controlled to be 1:1.5:30; the deposition is performed for 100min to deposit a carbon nitride layer on the surface of the metal titanium layer of the graphite piece, and the thickness of the carbon nitride layer is 200nm; S3, methyltrichlorosilane and methylsilane are used as the dual precursor gas, the dual precursor gas, hydrogen and argon are introduced into the deposition chamber, the mass ratio between the methyltrichlorosilane and the methylsilane in the dual precursor gas is 1:1, the mass ratio between the dual precursor gas and the argon is 1:11, the mass ratio between the dual precursor gas and the hydrogen is 1:8, the pressure in the deposition chamber is controlled to be 2kPa, the deposition is divided into a first deposition stage and a second deposition stage, in the first deposition stage, the temperature of the deposition chamber is raised to 850℃, the deposition time is 20min, and the first deposition stage is completed; then the deposition chamber is raised to 1050℃ at a rate of 5℃ / min, and the gas introduction is maintained, the deposition is performed for 150min, and finally a silicon carbide layer is obtained on the surface of the carbon nitride layer of the transition layer, and the thickness of the silicon carbide layer is 5μm; S4, the introduction of the dual precursor gas and the hydrogen is stopped, the argon gas is maintained to flow, the temperature is kept at 1000℃ for 30min, then the pressure in the deposition chamber is adjusted to 120Pa, the plasma generator is started to perform the bombardment treatment on the surface of the silicon carbide coating for 100s at a power of 500W, the temperature is kept at 800℃ for 20min, then the argon atmosphere is maintained, the deposition chamber is cooled to 200℃, the argon gas is continuously filled to the normal pressure, and the deposition chamber is opened, and the graphite piece product with the silicon carbide coating deposited on the surface is obtained after cooling.

[0027] Example 4 In example 4, the temperature of the deposition chamber is raised to 500℃ after the argon gas is introduced when the carbon nitride layer is prepared in step S2.

[0028] Example 5 In example 5, the temperature of the deposition chamber is raised to 700℃ after the argon gas is introduced when the carbon nitride layer is prepared in step S2.

[0029] Example 6 In example 6, the deposition time is 60min when the carbon nitride layer is prepared in step S2.

[0030] Example 7 Example 7 is based on example 3, in example 7, the deposition time is 140 min when preparing the carbon nitride layer in step S2.

[0031] Example 8 Example 8 is based on example 3, in example 8, the mass ratio between melamine, acetylene and argon is 1 :0.6:30 when preparing the carbon nitride layer in step S2.

[0032] Example 9 Example 9 is based on example 3, in example 9, the mass ratio between melamine, acetylene and argon is 1 :2.4:30 when preparing the carbon nitride layer in step S2.

[0033] Example 10 Example 10 is based on example 3, in example 10, the mass ratio between methyltrichlorosilane and methylsilane in the double precursor gas is 1 :0.2.

[0034] Example 11 Example 11 is based on example 3, in example 11, the mass ratio between methyltrichlorosilane and methylsilane in the double precursor gas is 1 :2.

[0035] Example 12 Example 12 is based on example 3, in example 12, the mass ratio between the double precursor gas and argon in step S3 is 1 :5.

[0036] Example 13 Example 13 is based on example 3, in example 13, the mass ratio between the double precursor gas and argon in step S3 is 1 :17.

[0037] Example 14 Example 14 is based on example 3, in example 14, the temperature of the deposition chamber in the first deposition phase of step S3 is 700°C.

[0038] Example 15 Example 15 is based on example 3, in example 15, the temperature of the deposition chamber in the first deposition phase of step S3 is 1000°C.

[0039] Example 16 Example 16 is based on example 3, in example 16, the deposition time in the first deposition phase of step S3 is 10 min.

[0040] Example 17 Example 17 is based on example 3, in example 17, the deposition time in the first deposition phase of step S3 is 30 min.

[0041] Example 18 Example 18 is based on Example 3, and the deposition chamber temperature in the second deposition stage of step S3 of Example 18 is 900℃.

[0042] Example 19 Example 19 is based on Example 3, and the deposition chamber temperature in the second deposition stage of step S3 of Example 19 is 1200℃.

[0043] Example 20 Example 20 is based on Example 3, and the deposition time in the second deposition stage of step S3 of Example 20 is 100min.

[0044] Example 21 Example 21 is based on Example 3, and the deposition time in the second deposition stage of step S3 of Example 21 is 200min.

[0045] Comparative Example 1 Comparative Example 1 is based on Example 3, and there is no titanium metal layer in the transition layer of Comparative Example 1.

[0046] Comparative Example 2 Comparative Example 2 is based on Example 3, and there is no carbon nitride layer in the transition layer of Comparative Example 2.

[0047] Comparative Example 3 Comparative Example 3 is based on Example 3, and there is no transition layer in Comparative Example 3.

[0048] Comparative Example 4 Comparative Example 4 is based on Example 3, and the dual precursor gas is replaced by only methyltrichlorosilane gas in Comparative Example 4.

[0049] Comparative Example 5 Comparative Example 5 is based on Example 3, and the dual precursor gas is replaced by only methylsilane gas in Comparative Example 5.

[0050] The samples of Examples 1-21 and Comparative Examples 1-5 are subjected to the following performance tests: (1) Anti-peeling performance The anti-peeling performance of the samples is tested according to GB / T 32971-2016, using a scratch tester equipped with a diamond indenter (tip radius 200μm), the indenter is perpendicular to the sample surface, moving at a speed of 10mm / min, and applying a load of 0N linearly increasing to 100N, the scratch length is 10mm, the critical point of coating failure is monitored synchronously by acoustic emission sensor and optical microscope, the load corresponding to the first continuous peeling of the coating is defined as the critical load Lc, the higher the Lc value, the stronger the system bonding ability; each sample is tested 3 times, the average value is taken, and the test results are filled in Table 1.

[0051] (3) Impact toughness The impact strength of the sample was tested according to GB / T 229-2020, and each sample was tested 3 times to take the average value, and the test results were filled in Table 1.

[0052] Table 1 Performance test results of examples 1-21 and comparative examples 1-5 It can be seen from Table 1 that the critical load of examples 1-3 is 42 and above, which shows that the graphite piece with a surface deposited silicon carbide coating prepared by the present application has good anti-peeling performance. The impact toughness of examples 1-3 is 3.2 kJ / m 2 and above, which shows that the graphite piece with a surface deposited silicon carbide coating prepared by the present application has good mechanical strength.

[0053] In examples 4 and 5, the temperature during the settling after the argon gas is introduced in the preparation of the carbon nitride layer in step S2 is not within the range defined by the present application. When the temperature of the deposition chamber is too low, the reactivity of melamine and acetylene is insufficient, and it is difficult to form a complete carbon nitride. The structure of the obtained carbon nitride layer is loose, the bonding between the carbon nitride layer and the titanium layer is reduced, and the stability is insufficient. When the temperature of the deposition chamber is too high, the carbon nitride will be pyrolyzed, resulting in the loss of nitrogen element, and the compatibility of the carbon nitride layer is reduced, and the interface bonding is reduced.

[0054] In examples 6 and 7, the deposition time during the preparation of the carbon nitride layer in step S2 is not within the range defined by the present application. When the deposition time is too short, the thickness of the generated carbon nitride is too thin, and local decomposition may occur during the subsequent high-temperature deposition of silicon carbide, thereby reducing the quality of the product prepared and the uniformity of the coating. When the deposition time is too long, the carbon nitride layer is too thick, and cracks are generated inside during the subsequent high-temperature deposition process, affecting the overall stability of the system.

[0055] In examples 8 and 9, the mass ratio between melamine, acetylene and argon during the preparation of the carbon nitride layer in step S2 is not within the range defined by the present application. When the proportion of acetylene is too small, the carbon source in the deposition chamber is insufficient, thereby increasing the nitrogen content of the carbon nitride layer, resulting in a decrease in density and stability. When the proportion of acetylene is too large, a carbon-rich amorphous carbon film will be deposited, and the chemical bonding performance between the amorphous carbon film and the silicon carbide will be reduced, and therefore the interface bonding performance will be reduced.

[0056] The mass ratio between methyltrichlorosilane and methylsilane in the dual precursor gas in Example 10 and Example 11 is not within the range defined in the present application. When the proportion of methylsilane is too small, the activity of the system decreases, it is difficult to nucleate in the first deposition stage, thereby reducing the uniformity of the entire silicon carbide coating, and finally reducing the bonding performance of the entire silicon carbide coating. When the proportion of methylsilane is too large, the activity of the system is too high, the reaction is too fast, and the deposited silicon carbide coating is non-uniform and has reduced stability.

[0057] The mass ratio between the dual precursor gas and argon in step S3 in Example 12 and Example 13 is not within the range defined in the present application. When the proportion of argon decreases, it is difficult to sufficiently dilute the dual precursor gas, and the deposited silicon carbide coating is rough and has reduced bonding performance. When the proportion of argon is too high, the dual precursor gas is too diluted, the deposition rate is too slow, and the coating is non-uniform.

[0058] The deposition chamber temperature in the first deposition stage in Example 14 and Example 15 is not within the range defined in the present application. When the first stage deposition chamber temperature is too low, it is difficult to activate the decomposition and migration of methylsilane, and the silicon carbide coating is non-uniform. When the first deposition stage deposition chamber temperature is too high, the dual precursor gas is deposited simultaneously, and the temperature is too high, the carbon nitride layer is decomposed, and the system stability decreases.

[0059] The deposition time in the first deposition stage in Example 16 and Example 17 is not within the range defined in the present application. When the deposition time is too short, a continuous film cannot be formed, and finally the overall bonding performance of the silicon carbide layer is affected. When the deposition time is too long, grain coarsening occurs, stress is introduced, and the stability of the system is affected.

[0060] The deposition chamber temperature in the second deposition stage in Example 18 and Example 19 is not within the range defined in the present application. When the deposition chamber temperature is too low, the methyltrichlorosilane reaction in the second deposition stage is insufficient, and the uniformity of the generated silicon carbide coating decreases. When the deposition temperature is too high, the interface elements of the system will accelerate diffusion, thereby destroying the bonding between the interfaces.

[0061] The deposition time in the second deposition stage in Example 20 and Example 21 is not within the range defined in the present application. When the deposition time is too short, the thickness of the silicon carbide coating is insufficient, and the mechanical performance is affected. When the deposition time is too long, the coating is too thick, stress accumulates, and cracking occurs.

[0062] In Comparative Example 1, the transition layer does not have a metal titanium layer, and the carbon nitride layer cannot be connected to the system through Ti, and the bonding performance of the carbon nitride layer and the surface of the graphite piece is severely reduced.

[0063] In Comparative Example 2, the transition layer does not have a carbon nitride layer, and in the subsequent thermal deposition process, the thermal expansion coefficient difference is large, and subsequent cracking occurs.

[0064] In Comparative Example 3, there is no transition layer, the thermal expansion coefficient between silicon carbide and graphite is more obvious, and the bonding performance is seriously decreased.

[0065] In Comparative Example 4, the double precursor gas is only methyltrichlorosilane, the internal stress of the coating is large, and the bonding performance is decreased.

[0066] In Comparative Example 5, the double precursor is only methylsilane, the performance stability is decreased, and the bonding performance between the coatings is poor.

[0067] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined by the scope of the claims.

Claims

1. A process for depositing a silicon carbide coating on the surface of a graphite article, characterized by: The method comprises the following steps: S1, placing the cleaned graphite piece in a deposition chamber, closing the chamber, and performing vacuumizing; S2, depositing a transition layer on the surface of the graphite piece, S3, introducing double precursor gas, hydrogen and argon into the deposition chamber to deposit a silicon carbide layer on the surface of the transition layer; S4, stopping the introduction of gas, using inert gas plasma to etch the surface after a period of heat preservation, and obtaining the product after further heat preservation; The double precursor gas comprises methyltrichlorosilane and methylsilane.

2. The process for depositing a silicon carbide coating on the surface of a graphite article according to claim 1, characterized in that: The mass ratio between the methyltrichlorosilane and the methylsilane is 1:(0.4-1.6).

3. The process of claim 2 wherein: The mass ratio between the double precursor gas and the argon is 1:(8-14).

4. The process of claim 3, wherein: The deposition of the silicon carbide layer comprises a first deposition stage and a second deposition stage, the temperature of the first deposition stage is 800-900℃, and the time is 15-25min, the temperature of the second deposition stage is 950-1150℃, and the time is 120-180min.

5. The process for depositing a silicon carbide coating on the surface of a graphite article according to claim 1, wherein: The transition layer comprises a metal titanium layer and a connecting layer, the metal titanium layer is attached to the surface of the graphite piece, and the connecting layer is deposited on the surface of the metal titanium layer, the metal titanium layer is deposited by physical vapor deposition.

6. The process for depositing a silicon carbide coating on a graphite article of claim 5 wherein: The connecting layer comprises a carbon nitride layer, and the precursor of the carbon nitride layer comprises melamine and acetylene.

7. The process of claim 6 wherein: The deposition of the carbon nitride layer adopts the following steps: Raising the temperature of the deposition chamber, introducing argon to make the pressure of the deposition chamber 350-550Pa, heating the melamine, mixing it with argon, introducing it into the deposition chamber, simultaneously introducing acetylene gas into the deposition chamber, and depositing to obtain the carbon nitride layer.

8. The process of claim 7, wherein: The mass ratio between the melamine, acetylene and argon is 1:(1.1-1.9):

30.

9. The process of claim 7, wherein: The deposition temperature during the deposition is 570-620℃, and the deposition time is 90-110min.

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