Precursor feeding system and method for preparing ta c coating by chemical vapor deposition

Abstract

The application discloses a precursor feeding system and method for preparing a TaC coating by a chemical vapor deposition method. The system comprises a precursor tank, a first buffer tank and a second buffer tank which are connected in series and are each provided with a heat preservation layer. The heat conduction uniformity of the precursor TaCl5 powder is improved by adding a heat-conducting inert material in the precursor tank, so that stable sublimation is realized. A flow guide weir is arranged in the first buffer tank to realize stable gas flow. A honeycomb flow guide core is arranged in the second buffer tank to realize uniform flow and stable pressure. The application solves the problems of uneven sublimation of TaCl5 powder, large gas flow pulsation and low mixing efficiency in the prior art, realizes stable conveying with a gas flow fluctuation of less than or equal to 5%, and thus provides a prerequisite guarantee for obtaining a high-density TaC coating with uniform thickness, improving the quality of the TaC coating and the deposition efficiency.

Description

Technical Field

[0001] This application belongs to the field of high-temperature coating preparation technology, specifically a precursor feeding system and method for preparing TaC coatings by chemical vapor deposition, which is used to achieve stable sublimation, airflow homogenization and transport control of TaCl precursor. Background Technology

[0002] Tantalum carbide (TaC) coatings are widely used in high-temperature structural components, wear-resistant tools, aerospace thermal protection materials, and semiconductor devices due to their high melting point (approximately 3880 ℃), high hardness, excellent corrosion resistance, and thermal stability. Chemical vapor deposition (CVD) is the mainstream process for preparing high-quality TaC coatings. To obtain TaC coatings with high purity, good density, controllable thickness, and excellent uniformity, the sublimation of the precursor tantalum pentachloride (TaCl5) and stable gas phase transport are crucial. If uneven heating, evaporation rate fluctuations, or gas flow pulsations occur during the precursor feeding process, it will lead to uneven TaC coating thickness, increased defects, or even deposition failure. Therefore, achieving uniform sublimation and stable, controllable transport of the precursor is one of the key technical issues in ensuring the quality of CVD-TaC coatings.

[0003] Due to the poor thermal conductivity of TaCl5, the temperature field distribution during the sublimation process in the precursor tank is uneven, and the vaporization rate is unstable. Simultaneously, particulate raw materials are prone to accumulation and unstable fluctuations during powder feeding, resulting in significant variations in the concentration and flow rate of the vapor tantalum source entering the deposition furnace. Furthermore, existing gas buffering and mixing devices are simple in structure, making it difficult to achieve sufficient mixing and stable supply of multi-component process gases. Therefore, a feeding system and method capable of achieving uniform sublimation of TaCl5, stable gas flow, and efficient mixing is needed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a feed system and method for preparing TaC coating precursors using chemical vapor deposition, which enables stable sublimation, gas flow homogenization, and transport control of TaCl5 precursors.

[0005] To achieve the above objectives, this invention provides a precursor feeding system for preparing TaC coatings using chemical vapor deposition, comprising a precursor tank with an inner wall insulated, a primary buffer tank, a secondary buffer tank, and a conveying pipeline. The precursor tank, primary buffer tank, and secondary buffer tank are sequentially connected via the conveying pipeline, wherein:

[0006] The precursor tank is equipped with a surrounding heating device, which includes a feed sublimation section, an airflow buffer section and an airflow stabilization section that are connected in sequence. The feed sublimation section is filled with a thermally conductive inert material to improve the thermal conductivity of the external precursor raw material. A first flow equalization plate is provided at the connection between the airflow buffer section and the airflow stabilization section to reduce airflow fluctuations. A second flow equalization plate is provided at the connection between the feed sublimation section and the airflow buffer section to reduce sublimation gas airflow fluctuations.

[0007] The outlet end of the primary buffer tank is equipped with a guide weir to reduce cross-sectional velocity non-uniformity.

[0008] The secondary buffer tank is equipped with a honeycomb-shaped flow guide core for gas flow equalization and pressure stabilization, and the outlet end of the secondary buffer tank is connected to a conveying pipeline that communicates with the external deposition furnace.

[0009] In this feeding system, the precursor TaCl5 powder is mixed with a thermally conductive inert material in the feeding sublimation section, which significantly improves the heat transfer conditions of the feed bed, realizes uniform heating and stable sublimation of the precursor TaCl5 powder, and reduces the fluctuation of TaCl5 gas phase concentration. At the same time, the airflow fluctuation of the precursor gas phase is further reduced based on the first and second flow equalization disks.

[0010] The feeding system adopts a dual-buffer structure with a primary buffer tank for flow stabilization and a secondary buffer tank for pressure stabilization. Combined with the design of a guide weir and a honeycomb guide core, it effectively reduces the cross-sectional velocity non-uniformity of the precursor gas phase, thereby ensuring the continuity and uniformity of the subsequent TaC coating deposition process.

[0011] The insulation layer is a polytetrafluoroethylene coating insulation layer, and the precursor tank adopts a multi-point temperature control heating method based on a surrounding heating device to achieve uniform temperature field of the precursor raw materials.

[0012] The present invention also provides a method for feeding precursors based on the above-described feeding system, the method comprising the following steps:

[0013] S1. The precursor TaCl5 powder is transported to the precursor tank and mixed with the thermally conductive inert material. The precursor gas is sublimated into the precursor gas phase by multi-point temperature control heating through a surrounding heating device. Then, the gas phase of the precursor gas phase is reduced by the first flow equalization plate set in the precursor tank. The mass ratio of the precursor TaCl5 powder to the thermally conductive inert material is 3-5:1. The thermally conductive inert material is one or more of quartz sand, carbon powder or alumina balls.

[0014] S2. The precursor gas phase enters the primary buffer tank through the delivery pipeline. The cross-sectional velocity of the precursor gas phase is effectively reduced by the guide weir set in the primary buffer tank, so as to achieve stable flow of the precursor gas phase.

[0015] S3. The precursor gas phase enters the secondary buffer tank through the delivery pipeline, and under the action of the honeycomb guide core, the precursor gas phase is decomposed into multiple fine streams, thereby weakening the pressure pulsation caused by the local high-speed airflow and realizing gas phase homogenization. Then it can be delivered to the external deposition furnace through the delivery pipeline.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects:

[0017] (1) Uniform sublimation: By filling the precursor tank with a thermally conductive inert material mixed with the precursor TaCl5 powder, the heat conduction of the material bed can be effectively improved, so that the TaCl5 evaporation rate is stable, which solves the technical problem of large fluctuations in evaporation rate caused by uneven temperature field during sublimation in the prior art.

[0018] (2) Stable airflow: By setting up a double buffer structure with a primary buffer tank for stabilizing the flow and a secondary buffer tank for stabilizing the pressure, the non-uniformity of the interface flow rate of the precursor gas phase can be reduced to less than 15%, and the airflow fluctuation can be controlled within 5%, thereby ensuring the continuity and uniformity of the subsequent TaC coating deposition process. A high-density TaC coating with a thickness uniformity of ±3% can be obtained. The stable gas supply effectively improves the utilization rate of raw materials and deposition efficiency, reduces energy consumption and shortens the preparation cycle, thereby reducing production costs.

[0019] (3) Uniform mixing: The primary buffer tank is equipped with a guide weir and uses the static pressure of the gas to naturally homogenize it. The secondary buffer tank is equipped with a honeycomb guide core to decompose the inlet jet into uniform fine streams, realizing homogenization without stirring, avoiding secondary pollution, and significantly improving the mixing uniformity of multi-component gases. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the precursor feeding system in this invention.

[0022] Figure 2 for Figure 1 Top view,

[0023] Figure 3 for Figure 2 AA section view,

[0024] Figure 4This is a flowchart of the method for feeding precursors based on a feeding system in this invention.

[0025] In the diagram: 100. Precursor tank, 110. Surround heating device, 120. Feeding sublimation section, 130. Airflow buffer section, 140. Airflow stabilization section, 150. First flow equalization plate, 160. Second flow equalization plate, 200. Primary buffer tank, 210. Guide weir, 300. Secondary buffer tank, 310. Honeycomb guide core, 400. Conveying pipeline. Detailed Implementation

[0026] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the resin range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the resin range "0-5" indicates that all real numbers between "0-5" have been listed in this document; "0-5" is simply a shortened representation of these resin combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0028] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way.

[0030] like Figures 1-3 As shown, this application provides a precursor feeding system for preparing TaC coatings by chemical vapor deposition, which includes a precursor tank 100, a primary buffer tank 200, a secondary buffer tank 300, and a conveying pipeline 400, all with insulation layers on their inner walls. The precursor tank 100, the primary buffer tank 200, and the secondary buffer tank 300 are sequentially connected through the conveying pipeline 400, wherein:

[0031] A surround heating device 110 is provided on the outside of the precursor tank 100, which includes a feed sublimation section 120, an airflow buffer section 130 and an airflow stabilization section 140 that pass through in sequence. The feed sublimation section 120 is filled with a thermally conductive inert material to improve the thermal conductivity of the external precursor raw material. A first flow equalization plate 150 is provided at the connection between the airflow buffer section 130 and the airflow stabilization section 140 to reduce airflow fluctuations. A second flow equalization plate 160 is provided at the connection between the feed sublimation section 120 and the airflow buffer section 130 to reduce sublimation gas airflow fluctuations.

[0032] The outlet end of the primary buffer tank 200 is equipped with a guide weir 210 to reduce the non-uniformity of cross-sectional flow velocity;

[0033] The secondary buffer tank 300 is equipped with a honeycomb guide core 310 for gas flow equalization and pressure stabilization, and the outlet end of the secondary buffer tank 300 is connected to a conveying pipeline 400 that communicates with an external deposition furnace.

[0034] The feeding system adopts a dual-buffer structure with a primary buffer tank 200 for flow stabilization and a secondary buffer tank 300 for pressure stabilization. Combined with the design of the guide weir 210 and the honeycomb guide core 310, it effectively reduces the cross-sectional velocity non-uniformity of the precursor gas phase, thereby ensuring the continuity and uniformity of the subsequent TaC coating deposition process.

[0035] like Figure 4 As shown, this application also provides a method for feeding precursors based on the above-described feeding system, the method comprising the following steps:

[0036] S1. The precursor TaCl5 powder is transported to the precursor tank 100 and mixed with a thermally conductive inert material. The precursor gas is sublimated into a precursor gas phase by multi-point temperature control heating through a surrounding heating device 110. Then, the precursor gas phase is reduced in airflow by the first flow equalization plate 150 set in the precursor tank 100. The mass ratio of the precursor TaCl5 powder to the thermally conductive inert material is 3-5:1. The thermally conductive inert material is one or more of quartz sand, carbon powder or alumina balls.

[0037] It should be noted that in other embodiments, the precursor gas phase is further subjected to a second flow equalization disk 160 disposed in the precursor tank 100 to reduce airflow fluctuations. The second flow equalization disk 160 is disposed at the connection between the feed sublimation section 120 and the airflow buffer section 130.

[0038] S2. The precursor gas phase enters the primary buffer tank 200 through the conveying pipeline 400. The cross-sectional velocity of the precursor gas phase is effectively reduced by the guide weir 210 set in the primary buffer tank 200, so as to achieve stable flow of the precursor gas phase.

[0039] S3. The precursor gas phase enters the secondary buffer tank 300 through the conveying pipeline, and under the action of the honeycomb guide core 310, the precursor gas phase is decomposed into multiple fine streams, thereby weakening the pressure pulsation caused by the local high-speed airflow and realizing gas phase homogenization. Then, it can be conveyed to the external deposition furnace through the conveying pipeline 400.

[0040] To further illustrate the working principle and technical effects of the present invention, the following explanation will be based on the example of providing precursor gas phase to an external CVD deposition furnace using the feeding system and feeding method.

[0041] Example 1

[0042] 400 g of tantalum pentachloride (TaCl5) precursor powder with an average particle size between 140-160 μm was taken and fed into the precursor feeding system. After being processed by the precursor feeding system, the powder was supplied with a TaCl5–C3H6–H2–Ar mixed gas to the external CVD deposition furnace via pipeline 400. A TaC coating was then deposited on the graphite substrate. The specific steps are as follows:

[0043] (1) The obtained precursor TaCl5 powder and quartz sand are mixed at a ratio of 4:1 and loaded into the feed sublimation section 120. The heating is carried out by the multi-point temperature control heating method of the surrounding heating device 110. The temperature of the feed sublimation section 120 is controlled at 180±10℃, the temperature of the airflow buffer section 130 is controlled at 200±10℃, and the temperature of the airflow stabilization section 140 is controlled at 210±10℃, so as to achieve the stepwise uniform sublimation of TaCl5.

[0044] (2) The sublimated TaCl5 gas phase passes through the guide weir 210 set at the outlet of the primary buffer tank 200, which reduces the cross-sectional velocity non-uniformity of the TaCl5 gas phase to 15%. Then, it passes through the honeycomb guide core 310 set in the secondary buffer tank 300, which eliminates the inlet airflow pulsation and realizes the steady flow and pressure of the TaCl5 gas phase.

[0045] (3) After the TaCl5 gas phase is stabilized and the flow is stabilized, it is mixed with C3H6–H2–Ar through the delivery pipeline 400 and then enters the external CVD deposition furnace. It is deposited on the graphite substrate at 1300 ℃ and 2 kPa for 5 h to form a TaC coating with a thickness of 40 μm.

[0046] Example 2

[0047] Unlike Example 1, in Example 2, the precursor TaCl5 powder and quartz sand were mixed at a ratio of 3:1.

[0048] Example 3

[0049] Unlike Example 1, in Example 3, the precursor TaCl5 powder and quartz sand were mixed at a ratio of 5:1.

[0050] The gas flow rate fluctuations and the uniformity of TaC coating thickness after deposition were detected in the external CVD deposition furnace in Examples 1-3, respectively. The detection results are shown in Table 1.

[0051] Table 1. Gas flow rate fluctuations and uniformity of TaC coating thickness after deposition during the deposition process in the external CVD deposition furnace in Examples 1-3.

[0052]

[0053] As can be seen from Table 1, the gas flow rate fluctuation of the mixed gas provided by the precursor feeding system in Examples 1-3 is less than 4.2%, and the thickness uniformity of the TaC coating deposited in the external CVD deposition furnace based on this mixed gas is within ±3%. Therefore, the precursor feeding system and method provided by the present invention can achieve stable sublimation, gas flow homogenization, and transport control of TaCl5 precursor.

[0054] It should be noted that in the above embodiments, the conveying pipeline 400 is a stainless steel pipe, and the insulation layer is an electric heating belt covering the outside of the precursor tank 100, the primary buffer tank 200, the secondary buffer tank 300 and the conveying pipeline 400.

[0055] The foregoing provides a detailed description of a precursor feeding system and method for preparing TaC coatings using chemical vapor deposition. Specific examples have been used to illustrate the principles and implementation methods of this application; the descriptions of these embodiments are merely for the purpose of helping to understand the core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A precursor feeding system for preparing TaC coatings by chemical vapor deposition, characterized in that, The system includes a precursor tank (100) with an inner wall insulated, a primary buffer tank (200), a secondary buffer tank (300), and a delivery pipeline (400). The precursor tank (100), the primary buffer tank (200), and the secondary buffer tank (300) are connected sequentially through the delivery pipeline (400). A surround heating device (110) is provided on the outside of the precursor tank (100), which includes a feed sublimation section (120), an airflow buffer section (130) and an airflow stabilization section (140) that pass through in sequence. The feed sublimation section (120) is filled with a thermally conductive inert material to improve the thermal conductivity of the external precursor raw material. A first flow equalization plate (150) is provided at the connection between the airflow buffer section (130) and the airflow stabilization section (140) to reduce airflow fluctuations. A second flow equalization plate (160) is provided at the connection between the feed sublimation section (120) and the airflow buffer section (130) to reduce sublimation gas airflow fluctuations. The outlet end of the primary buffer tank (200) is provided with a guide weir (210) to reduce the cross-sectional velocity non-uniformity. The secondary buffer tank (300) is equipped with a honeycomb guide core (310) for gas flow equalization and pressure stabilization.

2. The feeding system according to claim 1, characterized in that, The thermally conductive inert material is one or more of quartz sand, carbon powder, or alumina spheres.

3. The feeding system according to claim 1, characterized in that, The outlet end of the secondary buffer tank (300) is connected to a conveying pipeline (400) that communicates with an external deposition furnace.

4. The feeding system according to claim 1, characterized in that, The precursor tank (100) uses a multi-point temperature control heating method based on the surrounding heating device (110) to achieve uniform temperature field of the precursor raw material.

5. The feeding system according to claim 1, characterized in that, The insulation layer is a polytetrafluoroethylene (PTFE) coated insulation layer.

6. A method for feeding precursors based on the feeding system according to any one of claims 1-5, characterized in that, The method includes the following steps: S1. The precursor TaCl5 powder is transported to the precursor tank (100) and mixed with a thermally conductive inert material. It is then sublimated into the precursor gas phase by multi-point temperature control heating through a surrounding heating device. The precursor gas phase is then reduced in airflow through the first flow equalization plate (150) set in the precursor tank (100). S2. The precursor gas phase enters the primary buffer tank (200) through the delivery pipeline (400). The cross-sectional velocity of the precursor gas phase is effectively reduced by the guide weir (210) set in the primary buffer tank (200), thereby achieving stable flow of the precursor gas phase. S3. The precursor gas phase enters the secondary buffer tank (300) through the conveying pipeline (400), and under the action of the honeycomb guide core (310), the precursor gas phase is decomposed into multiple fine streams, thereby weakening the pressure pulsation caused by the local high-speed airflow and realizing gas phase homogenization. Then it can be conveyed to the external deposition furnace through the conveying pipeline (400).

7. The method according to claim 6, characterized in that, In step S1, the mass ratio of the precursor TaCl5 powder to the thermally conductive inert material is 3-5:1.

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