Vapor deposition method of carbon-based composite material
By using a layered gas-guided carrier disk in a large-size vapor deposition furnace to place the prefabricated body in a layered manner and adjust the reaction rates of the high-temperature and low-temperature zones respectively, the problem of uneven carbon deposition is solved, and the efficient and compactness of carbon-based composite materials is achieved and uniform deposition.
Patent Information
- Application Number
- CN202411383300.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-01-10
AI Technical Summary
In large-size vapor deposition furnaces, carbon deposition of carbon-based composite materials is prone to inhomogeneous heating and uneven reaction rates, resulting in insufficient material density and density.
The prefabricated body is placed in layers by using a layered guide air carrier disk to isolate the high-temperature zone and low-temperature zones, and carbon source gas of different compositions and flow rates are respectively passed through to regulate the reaction rate to achieve uniform deposition.
By regulating the reaction rate and gas flow, uniform deposition of carbon-based composite materials in large-size furnaces is achieved, the density and density of the material are improved, and the problem of uneven carbon deposition is avoided.
Smart Images
Figure CN119287340A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of vapor deposition, and relates to a vapor deposition method of a carbon-based composite material, and specifically relates to a vapor deposition method of a carbon-based composite material in a large-sized vapor deposition furnace. Background Art
[0002] The preparation of carbon matrix mainly includes the following ways: carbonizing the carbon fiber reinforced material coking polymer matrix and then high temperature treatment; or vapor deposition of hydrocarbons in the pores of carbon fiber preforms, and thermal decomposition to generate pyrolytic carbon, and then high temperature treatment. In the process of preparing carbon matrix, the carbon matrix generated by polymer pyrolysis is prone to pores and cracks, resulting in loose materials.
[0003] The most commonly used densification methods are liquid impregnation-carbonization and chemical vapor deposition (CVD). CVD is a complex high-temperature chemical reaction process that covers physical and chemical processes such as heat transfer, mass transfer, adsorption and desorption, and gas-solid chemical reactions. For large-sized vapor deposition equipment, due to its large size, when it performs vapor deposition of multiple carbon-based composite materials, the carbon-based composite materials need to be stacked and deposited in the furnace body, which easily leads to uneven heating and uneven carbon deposition. Summary of the invention
[0004] In order to solve the above technical problems, the present invention provides a method for vapor deposition of carbon-based composite materials, which can achieve simultaneous and uniform carbon deposition of multiple carbon-based composite materials in a large-sized vapor deposition furnace.
[0005] The technical solution adopted by the present invention is as follows:
[0006] A method for vapor deposition of a carbon-based composite material, the method comprising the following steps:
[0007] (1) placing the preforms in layers on a layered gas-conducting carrier plate in a vapor deposition furnace that can isolate a low-temperature zone and a high-temperature zone of the vapor deposition furnace, and evacuating the furnace;
[0008] The low temperature zone is the area from the center point of the vapor deposition furnace to one fifth to two fifths of the radius of the furnace cavity; the high temperature zone is the area other than the low temperature zone;
[0009] (2) raising the temperature of the vapor deposition furnace to 900-1180° C., and introducing a mixture of a carbon source and a non-reactive gas into the high temperature zone and the low temperature zone of the vapor deposition furnace, respectively; wherein the carbon source used in the high temperature zone is methane; the carbon source used in the low temperature zone is propane; and the gas flow ratio of the carbon source in the low temperature zone to the carbon source in the high temperature zone is 1:1.3-2.0;
[0010] (3) Stop introducing the mixed gas of carbon source and nitrogen source, pass nitrogen through the side wall of the furnace body, and open the furnace after cooling.
[0011] The size of the layered gas-conducting carrier plate is the same as the inner cavity size of the vapor deposition furnace, that is, the diameter of the layered gas-conducting carrier plate is the same as the inner cavity diameter of the vapor deposition furnace.
[0012] The layered gas guide carrier includes an gas guide plate 1, an isolation cover 2, and support columns 4; the gas guide plate 1 is multi-layered, and the isolation cover 2 is placed between the upper and lower gas guide plates 1 and is located in the area from the center point of the gas guide plate 1 to one-fifth to two-fifths of its radius; there are multiple support columns 4, and the support columns are evenly placed between the upper and lower gas guide plates 1.
[0013] The support columns are evenly placed between the upper and lower layers of the air guide disks 1 and at the edges of the air guide disks 1. In this way, the support columns can share a certain amount of pressure for the isolation cover and are more conducive to saving space on the air guide disk.
[0014] The gas guide plate 1 is provided with at least one through hole 3 for guiding gas, so as to facilitate the carrier gas to rise from the furnace bottom to the furnace top;
[0015] Grooves for engaging the support columns 4 are evenly arranged at the edges of the air guide plate 1, so as to prevent the support columns from shifting and ensure that the isolation cover and the support columns are evenly stressed.
[0016] The gas guide plate 1, the isolation cover 2 and the support column 4 are all made of graphite, which has good heat resistance and thermal conductivity. The wall thickness of the isolation cover 2 is 20 to 50 mm, so the isolation cover with such a thick wall has good thermal conductivity and will not affect the heat transfer.
[0017] The components of the layered gas-conducting carrier are independent of each other and can be assembled and disassembled layer by layer, which facilitates the placement and removal of the prefabricated body and is easy to use.
[0018] Furthermore, in step (1), the pressure is evacuated to below 1 kPa.
[0019] In step (2), the deposition time is controlled to be 150 to 300 hours and the deposition pressure is controlled to be 2 to 10 kPa.
[0020] In step (2), the volume percentage of the carbon source in the mixed gas is 80-90%, and the volume percentage of the non-reactive gas is 10-20%.
[0021] In step (2), in the low temperature zone, the gas flow rate of the carbon source is 10 to 30 m 3 / h; in the high temperature zone, the gas flow rate of the carbon source is 15~45m 3 / h
[0022] In step (2), the non-reactive gas is any one or more of argon and nitrogen.
[0023] In step (2), a mixed gas of a carbon source and a nitrogen source is introduced through an air inlet at the bottom of the vapor deposition furnace.
[0024] In step (3), the cooling refers to cooling to below 50°C.
[0025] The heating elements of a large-sized vapor deposition furnace are located on the side walls of the deposition furnace, so that the temperature near the furnace wall is higher and is called the high-temperature zone, while the temperature in the center of the furnace is lower and is called the low-temperature zone. Due to the uneven temperature, when carrier gas is introduced into the furnace, the reaction rates of the deposition in the high-temperature zone and the low-temperature zone are uneven, the reaction rate in the high-temperature zone is too fast and the reaction rate in the low-temperature zone is too slow, resulting in uneven carbon deposition of carbon-based composite materials in different parts of the furnace body.
[0026] The gas phase deposition method of carbon-based composite materials provided by the present invention enables the carbon-based composite materials to be dispersed and evenly placed in layers in the furnace to avoid mutual accumulation by using a layered gas-conducting carrier plate, and isolates the high temperature and low temperature zones of the gas phase deposition furnace from each other, so that it is convenient to introduce carrier gases of different compositions or flows into the high temperature zone and the low temperature zone, respectively, and then react with the preforms placed in the high temperature zone and the low temperature zone, respectively. The present invention introduces a high flow rate and low reactivity reaction gas into the high temperature zone, which can relatively reduce the reaction rate in the high temperature zone, and introduces a low flow rate and high reactivity reaction gas into the low temperature zone, which can relatively increase the reaction rate in the low temperature zone, so that the reaction rates of the high temperature zone and the low temperature zone can be equalized, and the uniformity of the reaction can be improved; the pyrolytic carbon is promoted to be quickly deposited into the preform, and the efficient densification of the preform is achieved, and the density and uniformity of the carbon-based composite materials deposited in a large-size furnace are improved.
[0027] The present invention adjusts the reaction rates at different positions of a large-scale vapor deposition furnace and forms a stable reaction flow field through the directional flow of the reaction gas, thereby promoting the rapid deposition of pyrolytic carbon into the interior of the preform, achieving efficient densification of the preform and improving the density and uniformity of the carbon-based composite material.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] 1. The present invention uses a layered gas-conducting carrier plate in a large-sized vapor deposition furnace to disperse and contain preforms in layers, thereby avoiding the accumulation of preforms in the furnace and affecting the uniformity of carbon deposition.
[0030] 2. The present invention isolates the high temperature and low temperature zones of the vapor deposition furnace from each other through a layered gas-conducting carrier plate, thereby facilitating the introduction of carrier gases of different compositions or flow rates into the high temperature zone and the low temperature zone, respectively, balancing the reaction rates of the high temperature zone and the low temperature zone, and controlling the uniformity of carbon deposition.
[0031] 3. The components of the layered gas-conducting carrier provided by the present invention are independent of each other and can be assembled and disassembled layer by layer, which facilitates the placement and removal of preforms. It is easy to use and can hold multiple preforms in one batch, thereby improving the efficiency of carbon deposition.
[0032] 4. The present invention introduces gas atmospheres of different flow rates and different reaction activities into the high temperature zone and the low temperature zone of the vapor deposition furnace, and utilizes the principles of thermodynamics and chemical kinetics to accurately control the internal and external reaction rates, thereby overcoming the problem caused by the uneven temperature distribution of the furnace body, and ultimately achieving uniform deposition of the preform in a large-scale vapor deposition furnace. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 It is a schematic diagram of the structure of a layered gas-conducting carrier;
[0034] Figure 2 is a schematic structural diagram of an air guide plate in a layered air guide carrier plate;
[0035] Figure 3 is a schematic diagram of placing a preform on a layered gas-conducting carrier;
[0036] Figure 4 Schematic diagram of the high temperature zone and low temperature zone of the vapor deposition furnace, where A-low temperature zone, B-high temperature zone;
[0037] Figure 5 is a SEM image of the exposed carbon fibers in the preform before deposition in Example 1;
[0038] Figure 6 This is a SEM image of the carbon fibers in the preform after being coated with pyrolytic carbon after deposition in Example 1;
[0039] In the figure, 1 is an air guide plate, 2 is an isolation cover, 3 is a through hole for air conduction, and 4 is a support column. DETAILED DESCRIPTION
[0040] The present invention is described in detail below with reference to the embodiments.
[0041] The vapor deposition furnace used in each embodiment and comparative example is cylindrical in shape, and its furnace body radius is 1650mm; the area within a radius of 600mm starting from the center point of the vapor deposition furnace is a low temperature zone; the area other than the low temperature zone is a high temperature zone.
[0042] The dimensions of the layered gas-conducting carrier used in each embodiment are the same as the inner cavity dimensions of the vapor deposition furnace; the layered gas-conducting carrier comprises a gas-conducting plate 1, an isolation cover 2, and support columns 4; the gas-conducting plate 1 is multi-layered, and the isolation cover 2 is placed between the upper and lower gas-conducting plates 1 and is within a 600mm radius area starting from the center point of the gas-conducting plate 1; there are multiple support columns 4, and the support columns are evenly placed between the upper and lower gas-conducting plates 1 and are at the edge of the gas-conducting plate 1; the gas-conducting plate 1 is provided with at least one through hole 3 for gas conduction; the edge of the gas-conducting plate 1 is also evenly provided with grooves for engaging the support columns 4; the gas-conducting plate 1, the isolation cover 2, and the support columns 4 are all made of graphite; the wall thickness of the isolation cover 2 is 350mm. The structure of the layered gas-conducting carrier is as follows: Figure 1 As shown, the structure of the air guide disc is as follows Figure 2 shown.
[0043] Example 1
[0044] A vapor deposition method for a large-size carbon-based composite material, the method comprising the following steps:
[0045] (1) placing the carbon material preforms side by side and in layers on a layered gas-conducting carrier in a vapor deposition furnace, and covering the preforms in the low-temperature zone with an isolation cover in the layered gas-conducting carrier, and evacuating the preforms to a vacuum of less than 1 kPa;
[0046] (2) The temperature of the vapor deposition furnace was raised to 1000°C, and a mixture of methane and nitrogen was introduced into the high temperature zone of the vapor deposition furnace, and a mixture of propane and nitrogen was introduced into the low temperature zone of the vapor deposition furnace; in the high temperature zone, the gas flow rate of methane was 15m / s. 3 / h, the gas flow rate of nitrogen is 3.75m 3 / h; in the low temperature zone, the propane gas flow rate is 10m 3 / h, the gas flow rate of nitrogen is 2.5m 3 / h; control the deposition time to 200h and the deposition pressure to 5kPa;
[0047] (3) Stop introducing the mixed gas of carbon source and nitrogen source, pass nitrogen through the side wall of the furnace, and open the furnace after cooling to 50°C.
[0048] The SEM image of the exposed carbon fibers in the preform before deposition is shown in Figure 2. Figure 5 As shown, the SEM image of the carbon fiber in the preform after deposition after coating with pyrolytic carbon is as follows Figure 6 As shown, it can be seen from the figure that the surface of the carbon fiber in the preform is tightly wrapped by pyrolytic carbon.
[0049] Example 2
[0050] A vapor deposition method for a large-size carbon-based composite material, the method comprising the following steps:
[0051] (1) placing the carbon material preforms side by side and in layers on a layered gas-conducting carrier in a vapor deposition furnace, and covering the preforms in the low-temperature zone with an isolation cover in the layered gas-conducting carrier, and evacuating the preforms to a vacuum of less than 1 kPa;
[0052] (2) The temperature of the vapor deposition furnace was raised to 1100°C, and a mixture of methane and nitrogen was introduced into the high temperature zone of the vapor deposition furnace, and a mixture of propane and nitrogen was introduced into the low temperature zone of the vapor deposition furnace; in the high temperature zone, the gas flow rate of methane was 40m 3 / h, the gas flow rate of nitrogen is 5.0m 3 / h; in the low temperature zone, the propane gas flow rate is 30m 3 / h, the gas flow rate of nitrogen is 3.3m 3 / h; controlled deposition time 250h, deposition pressure 8kPa;
[0053] (3) Stop introducing the mixed gas of carbon source and nitrogen source, pass nitrogen through the side wall of the furnace, and open the furnace after cooling to 50°C.
[0054] Comparative Example 1
[0055] The other conditions are the same as those in Example 1, except that the preform is directly placed in the furnace without using a layered gas-conducting carrier, and the same methane and nitrogen mixed gas is introduced into both the high temperature zone and the low temperature zone of the vapor deposition furnace, and the gas flow rate of methane is 10m 3 / h, the gas flow rate of nitrogen is 2.5m 3 / h.
[0056] Comparative Example 2
[0057] The rest is the same as in Example 1, except that a mixed gas of methane and nitrogen is introduced into the high temperature zone and the low temperature zone of the vapor deposition furnace respectively; in the high temperature zone, the gas flow rate of methane is 15m 3 / h, the gas flow rate of nitrogen is 3.75m 3 / h; in the low temperature zone, the gas flow rate of methane is 10m 3 / h, the gas flow rate of nitrogen is 2.5m 3 / h; control the deposition time to 200h and the deposition pressure to 5kPa.
[0058] The average density of the carbon-based composite materials after deposition in the high temperature zone and the low temperature zone of the vapor deposition furnace in the above-mentioned embodiments and comparative examples is shown in Table 1.
[0059] Table 1
[0060] <![CDATA[High temperature zone / g / cm 3 > <![CDATA[Low temperature region / g / cm 3 > Example 1 1.02 1.04 Example 2 1.1 1.11 Comparative Example 1 0.95 0.86 Comparative Example 2 0.99 0.76
[0061] It can be seen from the above that the vapor phase deposition method of the carbon-based composite material provided by the present invention can control the uniformity of carbon deposition on all preforms in the furnace chamber.
[0062] The above-mentioned detailed description of the vapor deposition method of a carbon-based composite material with reference to the embodiment is illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.
Claims
1. A method for vapor deposition of a carbon-based composite material, characterized in that: The method comprises the following steps: (1) placing the preforms in layers on a layered gas-conducting carrier plate in a vapor deposition furnace that can isolate a low-temperature zone and a high-temperature zone of the vapor deposition furnace, and evacuating the furnace; The low temperature zone is the area from the center point of the vapor deposition furnace to one fifth to two fifths of the radius of the furnace cavity; the high temperature zone is the area other than the low temperature zone; (2) raising the temperature of the vapor deposition furnace to 900-1180° C., and introducing a mixture of a carbon source and a non-reactive gas into the high temperature zone and the low temperature zone of the vapor deposition furnace, respectively; wherein the carbon source used in the high temperature zone is methane; the carbon source used in the low temperature zone is propane; and the gas flow ratio of the carbon source in the low temperature zone to the carbon source in the high temperature zone is 1:1.3-2.0; (3) Stop introducing the mixed gas of carbon source and nitrogen source, pass nitrogen through the side wall of the furnace body, and open the furnace after cooling.
2. The vapor deposition method of carbon-based composite material according to claim 1, characterized in that: The dimensions of the layered gas-conducting carrier are the same as the dimensions of the inner cavity of a vapor deposition furnace; the layered gas-conducting carrier comprises a gas-conducting plate (1), an isolation cover (2), and support columns (4); the gas-conducting plate (1) is multi-layered, the isolation cover (2) is placed between the upper and lower gas-conducting plates (1) and is located in the area from the center point of the gas-conducting plate (1) to one-fifth to two-fifths of its radius; the support columns (4) are multiple, and the support columns are evenly placed between the upper and lower gas-conducting plates (1).
3. The vapor deposition method of carbon-based composite material according to claim 1, characterized in that: The support columns are evenly placed between the upper and lower layers of the air guide plates (1) and are located at the edges of the air guide plates (1).
4. The vapor deposition method of carbon-based composite material according to claim 1, characterized in that: The air guide plate (1) is provided with at least one through hole (3) for guiding air; and grooves for engaging support columns (4) are evenly arranged at the edge of the air guide plate (1).
5. The vapor deposition method of carbon-based composite material according to claim 1, characterized in that: The gas guide plate (1), the isolation cover (2) and the support column (4) are all made of graphite; the wall thickness of the isolation cover (2) is 20 to 50 mm.
6. The vapor deposition method of carbon-based composite material according to claim 1, characterized in that: In step (2), the deposition time is controlled to be 150 to 300 hours and the deposition pressure is controlled to be 2 to 10 kPa.
7. The vapor deposition method of carbon-based composite material according to claim 1, characterized in that: In step (2), the volume percentage of the carbon source in the mixed gas is 80-90%, and the volume percentage of the non-reactive gas is 10-20%.
8. The vapor deposition method of a carbon-based composite material according to any one of claims 1 to 7, characterized in that: In step (2), in the low temperature zone, the gas flow rate of the carbon source is 10 to 30 m 3 / h; in the high temperature zone, the gas flow rate of the carbon source is 15~45m 3 / h.
9. The vapor deposition method of a carbon-based composite material according to any one of claims 1 to 7, characterized in that: In step (2), the non-reactive gas is any one or more of argon and nitrogen.
10. The vapor deposition method of a carbon-based composite material according to any one of claims 1 to 7, characterized in that: In step (2), a mixed gas of a carbon source and a nitrogen source is introduced through an air inlet at the bottom of the vapor deposition furnace.