A flow guide device for a chemical vapor deposition furnace

Abstract

The application discloses a flow guide device of a chemical vapor deposition furnace, which comprises an Archimedes spiral flow guide cone and a cross flow guide support, the Archimedes spiral flow guide cone comprises a cone body and an Archimedes spiral, the Archimedes spiral is distributed on a conical surface of the cone body to form a flow guide groove, the cross flow guide support comprises a perforated base and a flow guide rod, the Archimedes spiral flow guide cone is inserted on the perforated base, and the perforated base is communicated with the flow guide rod. The application adopts the combined mode of the Archimedes spiral flow guide and the cross flow guide support, improves the deposition uniformity compared with other molds, ensures uniform mixing of multiple gases and controls uniform distribution of a gas flow field along a radial direction, and improves the deposition efficiency.

Description

Technical Field

[0001] This invention belongs to the field of membrane material growth, and specifically relates to a flow guiding device for a chemical vapor deposition furnace. Background Technology

[0002] Graphite possesses advantages such as high temperature resistance, high thermal and electrical conductivity, and excellent thermal shock resistance. However, its susceptibility to oxidation and corrosion at high temperatures severely limits its application in high-temperature thermal fields. TaC, on the other hand, is a material with a high melting point (3983℃), high hardness (15-19 GPa), and excellent chemical resistance. It also exhibits good chemical and mechanical compatibility with graphite and C / C composites. Due to these highly attractive properties, TaC coatings prepared on graphite surfaces via chemical vapor deposition are widely used in aerospace thermal protection, single crystal growth, energy electronics, and medical devices, such as rocket nozzles and scramjet engine components.

[0003] The preparation of TaC coatings using chemical vapor deposition (CVD) involves placing a graphite or C / C composite material as a substrate on a sample plate within a deposition furnace. Hydrocarbons (CH4, C3H6, etc.) are used as the carbon source, undergoing dehydrogenation and carbonization under high temperature and vacuum conditions. Subsequently, an in-situ carbonization reaction occurs on the graphite substrate surface with TaCl5, which serves as the tantalum source. By controlling factors such as temperature, pressure, residence time, and precursor concentration, a TaC coating is ultimately formed. On one hand, the distribution of gases and the uniformity of the flow field within the deposition space are crucial factors affecting the deposition effect. Uneven gas distribution leads to uneven deposition thickness, affecting product performance and extending production time. On the other hand, the use of multiple gases places higher demands on the design of the deposition chamber. Only by thoroughly and uniformly mixing CH4 and TaCl5 can the uniformity of the coating composition on the workpiece surface be guaranteed; otherwise, different areas of the coating surface will exhibit carbon deficiency or free carbon enrichment, severely impacting product quality and performance. Therefore, ensuring uniform mixing of various gases and a uniform flow field distribution is a pressing issue for manufacturers.

[0004] In chemical vapor deposition (CVD), the design of the gas transport path often has a significant impact on the deposition quality of the preform. On the one hand, the significant difference between the gas inlet pipe diameter and the diameter of the deposition chamber results in a severely uneven radial distribution of the gas flow field within the deposition chamber. On the other hand, the uniform mixing of multiple gases, such as CH4 and TaCl5, also urgently needs to be addressed. To address these issues, the patent "A Flow Field Control Device for a Chemical Vapor Deposition Furnace" (CN 215947406U) proposes the following solution: A "convex"-shaped "mixer" structure with an outlet on the top and an outlet on the side is added to the gas inlet of the deposition chamber. During production, the carbon source gas and carrier gas mix within the mixer and then are distributed to the deposition chamber through the various outlets, resulting in a more uniform gas flow distribution. Alternatively, as described in the patent "A Double-Helix Flue Gas Circulation Sintering Mixer" (CN206881534U), a turbulent flow platform is set within the reaction chamber, and the gas to be mixed is introduced into the inner chamber through the inlet, causing the two gases to flow in spirals and mix with each other, thereby forming strong turbulence and achieving uniform mixing. However, in industrial production, the ambient temperature is high when using a chemical vapor deposition furnace to deposit tantalum carbide coatings, which leads to a relatively high temperature near the inlet. Using the above method would result in most of the tantalum and carbon being deposited inside the mixer / fluidizer, severely affecting the deposition efficiency. Summary of the Invention

[0005] To address the problem of low deposition efficiency in chemical vapor deposition (CVD), this invention provides a flow guiding device for a CVD furnace, comprising an Archimedean spiral flow guide cone and a cross-shaped flow guide support. The Archimedean spiral flow guide cone includes a cone body and an Archimedean spiral, with the Archimedean spiral distributed on the cone surface of the cone body. The cross-shaped flow guide support includes a perforated base and a flow guide rod. The Archimedean spiral flow guide cone is inserted into the perforated base, and the perforated base is connected to the flow guide rod.

[0006] Preferably, the Archimedean spiral guide cone body has an Archimedean spiral groove engraved on its cone surface, and the guide groove is connected to the guide rod through a perforated base.

[0007] Preferably, the polar equation of the Archimedean spiral is:

[0008] r = a + bθ

[0009] Where a and b are: (b is the value that increases with each unit angle r of the helix. Changing parameter a is equivalent to rotating the helix, while parameter b controls the distance between two adjacent curves).

[0010] Preferably, the height of the cone body is between 1cm and 100cm.

[0011] Preferably, the circumference of the bottom surface of the cone body is between 1.5cm and 150cm.

[0012] Preferably, the connecting surface between the guide channel and the guide rod is a slope.

[0013] Preferably, the cross-section of the guide rod is pentagonal or right triangle.

[0014] Preferably, the number of guide rods is 4.

[0015] Preferably, the guide rods are arranged in a cross shape.

[0016] Preferably, the cross-shaped flow guide bracket further includes a support ring, which is snapped onto or embedded in the deposition wall of the deposition furnace, and the support ring is circular or square.

[0017] This invention employs a combination of an Archimedean spiral guide cone and a cross-shaped guide support, which improves deposition uniformity compared to other molds. It ensures uniform mixing of multiple gases and controls the radial distribution of the gas flow field, thereby improving deposition efficiency. The Archimedean spiral guide channel, obtained through four rotations on the cone surface, generates turbulence, ensuring thorough mixing of various gases and guaranteeing uniformity in gas composition. It successfully solves the problem of severely uneven radial distribution of the gas flow field in the deposition chamber caused by the significant difference between the gas inlet pipe diameter and the diameter of the deposition chamber, ensuring uniform deposition thickness of samples in various regions of the sample carrier.

[0018] Compared to traditional mixers / blenders, where the enclosed chamber causes most of the tantalum and carbon to deposit inside, severely affecting deposition efficiency, the small-sized Archimedes spiral guide cone and the sloping cross guide support designed in this invention not only achieve good mixing of multiple gases, but also avoid excessive contact with gases, thus preventing waste of raw materials and ensuring deposition efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a chemical vapor deposition flow guide device.

[0020] Figure 2 Front and top views of the Archimedes spiral guide cone;

[0021] Figure 3 This is a schematic diagram of the cross-shaped flow guide bracket;

[0022] Among them, 1 is the Archimedes spiral guide cone; 2 is the cross guide support; 3 is the Archimedes spiral guide groove; 4 is the guide cone bottom column; 5 is the perforated base; 6 is the guide rod; and 7 is the support ring. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example

[0025] This embodiment provides a flow guiding device for a chemical vapor deposition furnace, such as... Figure 1 As shown, it includes an Archimedean spiral guide cone 1 and a cross-shaped guide bracket 2, as... Figure 2 As shown, the Archimedean spiral guide cone includes a cone body and an Archimedean spiral. The Archimedean spiral is distributed on the cone surface of the cone body. The cone surface of the Archimedean spiral guide cone 1 is engraved with guide grooves 3 obtained by rotating the Archimedean spiral four times along the z-axis. The diameter of the guide grooves 3 is designed to be smaller at the top and larger at the bottom to ensure a better gas guiding effect. Figure 3 As shown, the cross-shaped flow guide bracket includes a perforated base 5 and a flow guide rod 6. The Archimedes spiral flow guide cone 1 is inserted into the perforated base 5, and the perforated base 5 is connected to the flow guide rod 6.

[0026] In this embodiment, the bottom post 4 of the Archimedes spiral guide cone 1 is inserted into the perforated base 5 and rotated at a certain angle so that the guide groove 3 on the cone body is aligned with the guide rod 6. The relative positions of the two parts are as follows: Figure 2 and Figure 3 As shown, the tail end of the guide groove 3 is aligned with the slope of the guide rod 6. The guide groove 3 is connected to the guide rod 6 through the perforated base 5. The connecting surface between the guide rod 6 and the guide groove 3 is a slope, which is to ensure that the airflow smoothly enters the lower cavity under the action of the guide rod 6.

[0027] In this embodiment, as Figure 3 As shown, the cross-shaped flow guide bracket 2 consists of three parts: a perforated base 5, flow guide rods 6, and a support ring 7. The cross-shaped flow guide bracket 2, formed by four pentagonal flow guide rods 6, ensures both support strength and minimizes obstruction to airflow, achieving a good flow guiding effect. The support ring 7, which is circular and placed on the wall of the sedimentation chamber, is used to fix the entire flow guide device within the sedimentation chamber. This support ring 7, embedded in the inner wall of the sedimentation chamber, serves to support the flow guide device.

[0028] In this embodiment, the height of the cone body is 60mm, the circumference of the bottom surface of the cone body is 94.25mm, the cross-section of the guide rod is pentagonal, and there are 4 guide rods, which are arranged in a cross shape.

[0029] During the deposition process, after the gas enters the deposition chamber axially, it is divided into four gas streams and increases radial velocity due to the presence of the Archimedes spiral guide cone 1. The gas is transported downward along the spiral surface, causing turbulence and rapid and uniform mixing, thus ensuring the uniformity of the gas phase components. In addition, compared to the initial gas stream which only has axial velocity, the increased radial velocity after the gas passes through the guide device ensures the uniformity of the radial distribution of the gas when it reaches the sample tray. This avoids the situation where most of the gas only passes near the central axis of the deposition chamber, resulting in coatings being deposited only on the sample surface near the central axis. Furthermore, the small size of the guide device and the small contact area with the gas prevent excessive tantalum carbide from being deposited on the surface, thus ensuring the utilization rate of the gas.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flow guiding device for a chemical vapor deposition furnace, characterized in that, The device includes an Archimedean spiral guide cone and a cross-shaped guide support. The Archimedean spiral guide cone comprises a cone body and an Archimedean spiral, which is distributed on the cone surface of the cone body. The cross-shaped guide support includes a perforated base and a guide rod. The Archimedean spiral guide cone is inserted into the perforated base, which is connected to the guide rod. The Archimedean spiral guide cone is connected to the guide rod through the perforated base. An Archimedean spiral is engraved on the cone surface of the Archimedean spiral guide cone to form a guide groove, which is connected to the guide rod through the perforated base.

2. The flow guiding device for a chemical vapor deposition furnace as described in claim 1, characterized in that, The polar equation of the Archimedean spiral is: in b To determine the corresponding increase in angle r for each unit increase in the spiral, change the parameter. a Equivalent to a rotating helix, and the parameters b This controls the distance between two adjacent curves.

3. The flow guiding device for a chemical vapor deposition furnace as described in claim 1, characterized in that, The height of the cone body ranges from 1 cm to 100 cm.

4. The flow guiding device for a chemical vapor deposition furnace as described in claim 1, characterized in that, The circumference of the bottom surface of the cone body ranges from 1.5 cm to 150 cm.

5. The flow guiding device for a chemical vapor deposition furnace as described in claim 1, characterized in that, The connecting surface between the guide channel and the guide rod is a slope.

6. The flow guiding device for a chemical vapor deposition furnace as described in claim 1, characterized in that, The cross-section of the guide rod is pentagonal or right triangle.

7. The flow guiding device for a chemical vapor deposition furnace as described in claim 1, characterized in that, The number of guide rods is 4.

8. The flow guiding device for a chemical vapor deposition furnace as described in claim 7, characterized in that, The guide rods are arranged in a cross shape.

9. The flow guiding device for a chemical vapor deposition furnace as described in claim 1, characterized in that, The cross-shaped flow guide bracket also includes a support ring, which is snapped onto or embedded in the deposition wall of the deposition furnace, and the support ring is circular or square.

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