Method for preparing tantalum carbide coating through chemical vapor deposition

Abstract

The invention discloses a method for preparing a tantalum carbide coating by using chemical vapor deposition, which is characterized in that aerosol containing a tantalum source and a carbon source is used as a raw material for chemical vapor deposition to form the tantalum carbide coating, and the aerosol containing the tantalum source and the carbon source contains a gaseous tantalum source and a solid carbon source dispersed in the gaseous tantalum source. According to the method, the aerosol containing the tantalum source and the carbon source is used as a raw material, the solid carbon source is uniformly dispersed in the gaseous tantalum source, the special precursor state increases the activity and dispersity of reactants, the reaction is easier to carry out on the molecular level, and compared with a traditional vapor deposition precursor, the reaction rate and the deposition efficiency can be improved; the preparation method has the advantages that the preparation method is simple, the reaction temperature requirement can be lowered, energy can be saved while stable quality of the tantalum carbide coating is ensured, loss of a heating element is reduced, the preparation method is low in energy consumption, high in deposition efficiency, stable and controllable in coating quality and the like, the high-quality tantalum carbide coating can be rapidly prepared, and industrial production is facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of preparation of tantalum carbide coating, and relates to a method for preparing tantalum carbide coating by chemical vapor deposition. BACKGROUND

[0002] Chemical vapor deposition (CVD) is an advanced process that utilizes gaseous substances to generate solid-state deposition on the surface of a solid by chemical reaction. It has unique advantages in the field of tantalum carbide coating preparation. It can achieve uniform coating deposition on complex-shaped substrates, has high control accuracy of coating composition and thickness, and the deposited coating has high purity and good density.

[0003] The existing method for preparing tantalum carbide coating by chemical vapor deposition mainly uses a powder feeder to send tantalum source (such as tantalum pentachloride, tantalum pentafluoride, etc.) into a sublimation tank. The solid carbon source powder is sublimated into gas at a certain temperature, and then the gaseous tantalum source is mixed with gaseous carbon source (such as propylene, methane, etc.) and carrier gas Ar, hydrogen in a gas mixing device, and then enters the reaction chamber for deposition reaction. However, the above method has the following defects: (1) Defects of powder feeding system, unstable coating quality.

[0004] The powder feeding equipment such as powder feeder is prone to powder jamming and powder breaking, which can easily cause imbalance of the stoichiometric ratio of tantalum and carbon during the deposition process, seriously affecting the deposition process and the quality of the tantalum carbide coating. For example, due to the imbalance of the stoichiometric ratio of tantalum and carbon (ideal Ta:C=1:1, actual deviation to 1:0.8 or 1:1.3), Ta2C or free carbon impurities are generated in the coating, which reduces the hardness and corrosion resistance of the coating (increases the corrosion rate).

[0005] (2) Insufficient carbon source activity, high energy consumption and equipment loss.

[0006] Using gaseous carbon sources such as methane / propylene requires high-temperature cracking, such as methane requiring >1200℃, i.e. high reaction temperature, generally requiring 1400-2000℃, which leads to short service life of heating elements, high energy consumption per furnace, and increased equipment maintenance costs.

[0007] (3) Low solid-gas mixing efficiency, limited reaction kinetics.

[0008] The solid tantalum source (powder) is first sublimated and gasified, and then mixed with gaseous carbon source (methane, propylene, etc.). The mixing path is short (only through a simple pipeline), and the molecular-level mixing is not uniform and sufficient, which increases the reaction activation energy and slows down the deposition rate.

[0009] Therefore, it is urgent to obtain a method for preparing tantalum carbide coating by chemical vapor deposition with low energy consumption, high deposition efficiency, stable and controllable coating quality, which plays an important role in promoting the widespread use of tantalum carbide coating. SUMMARY

[0010] The technical problem solved by the present application is to overcome the shortcomings of the prior art, and to provide a method for preparing a carbonized tantalum coating by chemical vapor deposition, which has low energy consumption, high deposition efficiency, stable and controllable coating quality.

[0011] To solve the above technical problems, the present application adopts the following technical solutions: A method for preparing a carbonized tantalum coating by chemical vapor deposition, the method is to carry out chemical vapor deposition with aerosol containing tantalum source and carbon source as raw material to form a carbonized tantalum coating; the aerosol containing tantalum source and carbon source contains gaseous tantalum source and solid carbon source dispersed in the gaseous tantalum source.

[0012] The above method is further improved, and the preparation method of the aerosol containing tantalum source and carbon source includes the following steps: S1, mixing carbon source powder and tantalum source powder, ball milling to obtain mixed powder; S2, sending the mixed powder obtained in step S1 into a powder feeder to form a stable powder feeding flow; S3, sending the stable powder feeding flow obtained in step S2 into a sublimation tank for sublimation, and simultaneously performing ultrasonic and atomization treatment to obtain an aerosol containing tantalum source and carbon source.

[0013] The above method is further improved, and in step S1, the carbon source powder is graphite powder; the purity of the graphite powder is ≥99.99%; the particle size of the carbon source powder is ≤200 μm; the tantalum source powder is at least one of tantalum powder, oxide of tantalum, halide of tantalum, organic compound of tantalum, and alloy of tantalum; the chloride of tantalum includes pentachlorotantalum or pentafluorotantalum.

[0014] The above method is further improved, and in step S1, the particle size of the mixed powder is ≤10 μm; the molar ratio of carbon powder and tantalum powder in the mixed powder is 1:1.

[0015] The above method is further improved, and in step S2, the powder feeder is at least one of a spiral vibration type powder feeder, a screw type powder feeder, an impeller type powder feeder, and an airflow type powder feeder; the powder feeding speed in the powder feeder is controlled to be ≤20 g / min.

[0016] The above method is further improved, and in step S3, the sublimation is carried out at a temperature of 80℃ to 400℃.

[0017] The above method is further improved, and the method for preparing a carbonized tantalum coating by chemical vapor deposition with aerosol containing tantalum source and carbon source as raw material includes the following steps: (1) mixing the aerosol containing tantalum source and carbon source, reducing gas and protective gas to form a mixed gas; (2) passing the mixed gas obtained in step (1) into a reaction chamber to perform a chemical vapor deposition reaction, thereby forming a tantalum carbide coating.

[0018] The method is further improved, and in step (1), the gas tank is used to mix the aerosol containing the tantalum source and the carbon source, the reducing gas and the protective gas to prepare the molecular-level mixed gas.

[0019] The method is further improved, and in step (1), the reducing gas is at least one of hydrogen and carbon monoxide; the flow rate of the reducing gas is 0.1 SLM-10 SLM; the protective gas is at least one of nitrogen and helium; and the flow rate of the protective gas is 0.5 SLM-10 SLM.

[0020] The method is further improved, and in step (2), the process parameters of the chemical vapor deposition reaction are as follows: the deposition temperature is 800-1200℃, and the deposition pressure is 0.5-5 kPa.

[0021] Compared with the prior art, the method has the following advantages: (1) In the method, the aerosol containing the tantalum source and the carbon source is used as the raw material, wherein the solid carbon source is uniformly dispersed in the gaseous tantalum source. This special precursor state increases the activity and dispersity of the reactants, makes the reaction more easily proceed at the molecular level, improves the reaction rate and the deposition efficiency, and possibly reduces the reaction temperature requirement. The method can ensure the quality stability of the tantalum carbide coating, save energy, and reduce the loss of the heating element.

[0022] (2) In the method, the mixture of the carbon source powder and the tantalum source powder is ball milled to prepare the mixed powder with a particle size of ≤10 μm. By optimizing the particle size of the mixed powder, the stoichiometric ratio of the tantalum-carbon raw material can be kept balanced, and the raw material can be more fully and stably reacted in the subsequent reaction, thereby reducing the coating composition deviation caused by the uneven raw material and improving the quality stability of the tantalum carbide coating.

[0023] (3) In the method, the superfine and high-purity graphite powder is used as the carbon source to replace the gaseous carbon source, which can significantly increase the surface activity of the carbon source, reduce the reaction activation energy, and thereby reduce the deposition temperature to 800-1200℃, thereby saving energy and reducing the loss of the heating element.

[0024] (4) In the method, the sublimation combined with ultrasonic and atomization is used to realize the solid-state sublimation and ultrasonic crushing of some substances, and then the gaseous tantalum source and the solid carbon aerosol are obtained by atomization. This unique process is a key step to form a suitable reaction precursor state.

[0025] (5) In the present application, the aerosol containing tantalum source and carbon source, reducing gas and protective gas are mixed to form a mixed gas with molecular level uniform mixing, realizing solid-gas molecular level uniform mixing and improving the reaction rate.

[0026] (6) In the present application, in the reaction chamber with a temperature of 800-1200℃, the flow rate of H2 is controlled to be 0.1-10 SLM, and the deposition pressure is 0.5-5 kPa, which provides precise and controllable conditions for tantalum carbide deposition, and then by precisely controlling the conditions of chemical vapor deposition reaction, a tantalum carbide coating with controllable thickness and quality is formed, which can meet the application scenarios with high requirements for coating thickness precision, such as precision mechanical parts and high-end electronic devices, and expand the application range of tantalum carbide coating.

[0027] Compared with the conventional chemical vapor deposition method, the method for preparing tantalum carbide coating by chemical vapor deposition has the advantages of low energy consumption, high deposition efficiency, stable and controllable coating quality, etc., and can quickly prepare high-quality tantalum carbide coating, which is convenient for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application.

[0029] Figure 1 The process flow diagram for preparing tantalum carbide coating by chemical vapor deposition in the embodiment 1 of the present application is shown in the figure. DETAILED DESCRIPTION

[0030] The present application will be further described below in combination with the drawings of the specification and specific preferred embodiments, but the protection scope of the present application is not limited thereby.

[0031] In the embodiments of the present application, the materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values of more than three repeated experiments, unless otherwise specified.

[0032] Embodiment 1: A method for preparing tantalum carbide coating by chemical vapor deposition, specifically using aerosol containing tantalum source and carbon source as raw material for chemical vapor deposition to form tantalum carbide coating, as shown in Figure 1 The method comprises the following steps: (1) Preparation of aerosol containing tantalum source and carbon source: S1, mix carbon source powder and tantalum source powder, ball mill to obtain mixed powder, specifically: The graphite powder with purity ≥99.99% and particle size ≤200 μm and the tantalum pentachloride powder are mixed according to a molar ratio of 1:1, and are placed in a ball mill for ball milling until the particle size of the powder is ≤10 μm, to obtain the mixed powder.

[0033] In this step, the tantalum source powder can also be at least one of tantalum powder, an oxide of tantalum, an organic compound of tantalum, and an alloy of tantalum.

[0034] In this step, the tantalum source powder can also be at least one of tantalum powder, an oxide of tantalum, an organic compound of tantalum, and an alloy of tantalum. The mixed powder obtained in step S1 is sent into a double helix vibration powder feeder, and a powder feeding speed is controlled to be 10 g / min, to form a stable powder feeding flow.

[0035] In this step, the powder feeder can also be a screw type powder feeder, an impeller type powder feeder, or an airflow type powder feeder.

[0036] In this step, the powder feeding speed can also be 1 g / min, 3 g / min, 5 g / min, 8 g / min, 11 g / min, 13 g / min, 15 g / min, 18 g / min, or 20 g / min. By optimizing and controlling the powder feeding speed, the powder feeding amount can be accurately controlled, the reactant ratio can be accurately controlled, a stable powder feeding flow with a required stoichiometric ratio can be obtained, and finally a stable carbonized tantalum coating can be obtained.

[0037] In this step, the powder feeding speed can also be 1 g / min, 3 g / min, 5 g / min, 8 g / min, 11 g / min, 13 g / min, 15 g / min, 18 g / min, or 20 g / min. By optimizing and controlling the powder feeding speed, the powder feeding amount can be accurately controlled, the reactant ratio can be accurately controlled, a stable powder feeding flow with a required stoichiometric ratio can be obtained, and finally a stable carbonized tantalum coating can be obtained. The temperature of the sublimation tank is controlled to be 300℃, the stable powder feeding flow obtained in step S2 is sent into the sublimation tank for sublimation, and ultrasonic and atomization treatments are simultaneously performed. In this process, the tantalum pentachloride is sublimated from a solid state to a gaseous state, and is broken by ultrasonic waves to improve the biochemical effect. Then, the solid graphite powder is uniformly dispersed in the gaseous tantalum pentachloride by atomization treatment to form an aerosol, and the aerosol containing gaseous tantalum pentachloride and solid graphite powder is obtained.

[0038] In this step, the temperature of the sublimation tank can also be controlled to be 80℃, 120℃, 180℃, 200℃, 230℃, 250℃, 280℃, 320℃, 350℃, 380℃, or 400℃.

[0039] In this step, the powder feeding speed can also be 1 g / min, 3 g / min, 5 g / min, 8 g / min, 11 g / min, 13 g / min, 15 g / min, 18 g / min, or 20 g / min. By optimizing and controlling the powder feeding speed, the powder feeding amount can be accurately controlled, the reactant ratio can be accurately controlled, a stable powder feeding flow with a required stoichiometric ratio can be obtained, and finally a stable carbonized tantalum coating can be obtained. The gaseous aerosol containing gaseous pentachloride tantalum and solid graphite powder, hydrogen and argon obtained in step S3 are introduced into a mixing tank according to a flow rate of 1 SLM of hydrogen and a flow rate of 1 SLM of argon, so as to mix the gaseous aerosol containing gaseous pentachloride tantalum and solid graphite powder, hydrogen and argon uniformly, and prepare a molecular level mixed gas.

[0040] In this step, the reducing gas can also be carbon monoxide, and the flow rate of the reducing gas is 0.1 SLM, 0.5 SLM, 0.8 SLM, 1.2 SLM, 1.8 SLM, 2 SLM, 2.5 SLM, 3 SLM, 4 SLM, 4.5 SLM, 5 SLM, 5.5 SLM, 6 SLM, 6.5 SLM, 7 SLM, 7.5 SLM, 8 SLM, 8.5 SLM, 9 SLM, 9.5 SLM, 10 SLM.

[0041] In this step, the protective gas can also be nitrogen, and the flow rate of the protective gas is 0.5 SLM, 0.8 SLM, 1.2 SLM, 1.8 SLM, 2 SLM, 2.5 SLM, 3 SLM, 4 SLM, 4.5 SLM, 5 SLM, 5.5 SLM, 6 SLM, 6.5 SLM, 7 SLM, 7.5 SLM, 8 SLM, 8.5 SLM, 9 SLM, 9.5 SLM, 10 SLM.

[0042] S5, introducing the mixed gas obtained in step S4 into a reaction chamber to perform a chemical vapor deposition reaction, wherein the process parameters of the chemical vapor deposition reaction are: a deposition temperature of 1000 ℃ and a deposition pressure of 3 kPa, so as to form a tantalum carbide coating.

[0043] In this step, the deposition temperature is also 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃; and the deposition pressure can also be 0.5 kPa, 1 kPa, 1.2 kPa, 1.8 kPa, 2.3 kPa, 2.8 kPa, 3.2 kPa, 3.7 kPa, 4 kPa, 4.3 kPa, 4.8 kPa, 5 kPa.

[0044] In this embodiment, the thickness of the tantalum carbide coating can be regulated according to the deposition time, the concentration of the reactants and the deposition pressure.

[0045] The method for preparing the carbonized tantalum coating in the application can control the problems of broken powder and clamped powder, improve the stability of equipment operation, has high reactivity of reactants, reduces the reaction temperature, and reduces the energy consumption of equipment by 15-20%, the deposition rate can reach 10-20 μm / h, and the thickness of the coating can be controlled within 5-50 μm, while the deposition rate of the conventional method is only 5-10 μm / h, no by-products such as carbon black, metallic tantalum and Ta2C are detected in the carbonized tantalum coating, the thickness of the coating is uniform, and the XRD result shows that the carbonized tantalum coating prepared in the application is mainly in the (200) and (111) crystal directions.

[0046] It can be known from the above results that, compared with the conventional chemical vapor deposition method, the method for preparing the carbonized tantalum coating by chemical vapor deposition in the application has the advantages of low energy consumption, high deposition efficiency, stable and controllable coating quality, and the like, and can quickly prepare a high-quality carbonized tantalum coating, which is convenient for industrial production, and the specific advantages are as follows: (1) In the application, the gas aerosol containing a tantalum source and a carbon source is used as a raw material, and the solid carbon source is uniformly dispersed in the gaseous tantalum source. This special precursor state increases the reactivity and dispersity of the reactants, makes the reaction more easily proceed at the molecular level, improves the reaction rate and deposition efficiency compared with the traditional gas deposition precursor, and can also reduce the reaction temperature requirement, thereby saving energy and reducing the loss of heating elements while ensuring the stability of the carbonized tantalum coating quality.

[0047] (2) In the application, the mixture of the carbon source powder and the tantalum source powder is ball milled to prepare a mixed powder with a particle size of ≤10 μm. By optimizing the particle size of the mixed powder, it can be ensured that the stoichiometric ratio of the tantalum-carbon raw material is always balanced, and the raw material can be more fully and stably reacted in the subsequent reaction, thereby reducing the coating composition deviation caused by uneven raw materials and improving the stability of the carbonized tantalum coating quality.

[0048] (3) In the application, the ultra-fine and high-purity graphite powder is used as the carbon source instead of the gaseous carbon source, which can significantly increase the surface activity of the carbon source and reduce the reaction activation energy, thereby reducing the deposition temperature to 800-1200 ℃, saving energy and reducing the loss of heating elements.

[0049] (4) In the application, the sublimation combined with ultrasonic and atomization can realize the solid-state sublimation and ultrasonic crushing of part of the substances, and then the gaseous tantalum source and the solid carbon gas aerosol are obtained by atomization. This unique process is a key step to form a suitable reaction precursor state.

[0050] (5) In the application, the gas aerosol containing a tantalum source and a carbon source, a reducing gas and a protective gas are mixed to prepare a molecularly mixed and uniform mixed gas, realizing the solid-gas molecular level uniform mixing, and improving the reaction rate.

[0051] (6) In the present application, in the reaction chamber with a temperature of 800-1200 DEG C, the flow rate of H2 is controlled to be 0.1-10 SLM, and the deposition pressure is 0.5-5 kPa, so that precise and controllable conditions are provided for the deposition of the tantalum carbide, and then by precisely controlling the conditions of the chemical vapor deposition reaction, the tantalum carbide coating with controllable thickness and quality is formed, the application scenarios with high requirements for the thickness precision of the coating, such as precision mechanical parts, high-end electronic devices and the like, can be met, and the application range of the tantalum carbide coating is expanded.

[0052] The above embodiments are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments. Any technical scheme falling within the concept of the present application belongs to the protection scope of the present application. It should be pointed out that, for ordinary skilled in the art, the improvements and refinements without departing from the principles of the present application should also be considered as the protection scope of the present application.

Claims

1. A method for producing a coating of tantalum carbide by chemical vapor deposition, characterized in that, The method is chemical vapor deposition using an aerosol containing a tantalum source and a carbon source as raw material to form a tantalum carbide coating layer; the aerosol containing a tantalum source and a carbon source comprises a gaseous tantalum source and a solid carbon source dispersed in the gaseous tantalum source.

2. The method of claim 1, wherein, The preparation method of the aerosol containing a tantalum source and a carbon source comprises the following steps: S1, mixing a carbon source powder and a tantalum source powder, ball milling to obtain a mixed powder; S2, feeding the mixed powder obtained in step S1 into a powder feeder to form a stable powder feeding flow; S3, feeding the stable powder feeding flow obtained in step S2 into a sublimation tank for sublimation, while performing ultrasonic and atomization treatment to obtain an aerosol containing a tantalum source and a carbon source.

3. The method of claim 2, wherein, In step S1, the carbon source powder is graphite powder; the purity of the graphite powder is ≥99.99%; the particle size of the carbon source powder is ≤200 μm; the tantalum source powder is at least one of tantalum powder, an oxide of tantalum, a halide of tantalum, an organic compound of tantalum, and an alloy of tantalum; the chloride of tantalum includes pentachlorotantalum or pentafluorotantalum.

4. The method of claim 3, wherein, In step S1, the particle size of the mixed powder is ≤10 μm; the molar ratio of carbon powder to tantalum powder in the mixed powder is 1:

1.

5. The method of claim 2, wherein, In step S2, the powder feeder is at least one of a spiral vibration type powder feeder, a screw type powder feeder, an impeller type powder feeder, and an airflow type powder feeder; the powder feeding speed in the powder feeder is controlled to be ≤20 g / min.

6. The method of claim 2, wherein, In step S3, the sublimation is performed at a temperature of 80℃ to 400℃.

7. The method according to any one of claims 1 to 6, characterized in that, The method of chemical vapor deposition using an aerosol containing a tantalum source and a carbon source as raw material to form a tantalum carbide coating layer comprises the following steps: (1) mixing the aerosol containing a tantalum source and a carbon source, a reducing gas, and a protective gas to form a mixed gas; (2) passing the mixed gas obtained in step (1) into a reaction chamber to perform a chemical vapor deposition reaction to form a tantalum carbide coating layer.

8. The method of claim 7, wherein, In step (1), a gas mixing tank is used to mix the aerosol containing a tantalum source and a carbon source, a reducing gas, and a protective gas to prepare a molecular level mixed gas.

9. The method of claim 8, wherein, In step (1), the reducing gas is at least one of hydrogen and carbon monoxide; the flow rate of the reducing gas is 0.1 SLM to 10 SLM; the protective gas is at least one of nitrogen and helium; the flow rate of the protective gas is 0.5 SLM to 10 SLM.

10. The method of claim 7, wherein, In step (2), the process parameters of the chemical vapor deposition reaction are: a deposition temperature of 800℃ to 1200℃, and a deposition pressure of 0.5 kPa to 5 kPa.

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