A large-charging-quantity carbon disc deposition device and a preparation method thereof

Abstract

The present application relates to a kind of carbon disc deposition equipment of large furnace quantity and its preparation method.The method includes the following: in the carbon source gas inlet pipe of deposition chamber, graphite base, regulator, prefabricated disc and graphite cover plate are sleeved, and a column prefabricated workpiece is formed;Several column prefabricated workpieces are sequentially loaded into deposition chamber and ensure spacing;Deposition furnace is heated, and constant temperature is maintained;The first gas inlet pipe of each group of carbon source gas inlet pipe is connected to natural gas, and the second gas inlet pipe is connected to propylene or propane, mixed and preheated in gas mixing tank to form mixed carbon source gas, then the deposition zone in the prefabricated workpiece covered by the carbon source gas inlet pipe is connected to the gas mixing pipe at the bottom of the deposition furnace;After the carbon source gas is retained in the prefabricated workpiece for a certain period of time and reacts, the nitrogen or argon gas introduced through the gas inlet pipe outside the prefabricated workpiece is carried away by the air hole, and the deposition chamber is discharged.The deposition process and furnace loading method are improved in a matched manner, and the carbon disc loaded into the deposition furnace can be efficiently deposited without using complex furnace tooling.

Description

Technical Field

[0001] This invention belongs to the field of carbon disc deposition technology, specifically relating to a carbon disc deposition device with a large furnace loading capacity and its preparation method. Background Technology

[0002] Carbon brake discs are one of the core components of current civil aircraft braking systems, serving as a friction element, a heat storage element, and a structural element in use.

[0003] Aircraft carbon brake discs are multiple discs arranged alternately with rotating and stationary discs. The rotating discs rotate with the tire, while the stationary discs are fixed to a torque cylinder. When pressure is applied, the rotating and stationary discs are pressed together, generating friction to stop the tire's rotation and achieve the aircraft braking effect. Therefore, carbon brake discs are required to have excellent frictional characteristics. Since the landing kinetic energy of large aircraft can reach tens of megajoules, the carbon brake discs must absorb the enormous heat energy generated by friction. Therefore, the carbon / carbon composite materials used for carbon brake discs require excellent mechanical and thermal properties. Generally, carbon / carbon composite materials with these properties are manufactured using chemical vapor deposition.

[0004] Currently, numerous manufacturers have developed various methods and researched new deposition processes and equipment for carbon disc deposition technology. These efforts aim to improve the key friction and thermal conductivity of the carbon disc, and significantly shorten the current production cycle and reduce production costs. However, these methods still have many shortcomings in terms of large furnace loading capacity and simplified deposition processes. Many require complex furnace tooling and the combined use of multiple gases, which are detrimental to increasing the furnace loading capacity and controlling the deposition process.

[0005] Currently, many production technologies and methods for carbon / carbon composite materials have been developed both domestically and internationally. The main directions are as follows: one is gradient deposition, which involves creating a gradient temperature field on the inner and outer edges of the workpiece for directional temperature gradient deposition. The deposition gas is mainly propylene or propane, and the carrier gas is nitrogen. This gradient deposition method has a small furnace loading capacity, typically only a few dozen trays per furnace, so it is rarely used in mass production. The other isothermal deposition method involves deposition in a uniform temperature field. This currently has two methods: forced flow and uniform isotropic diffusion, each with its own advantages, but both have revealed some weaknesses in practice.

[0006] The existing patent, application number CN202011589996.6, publication number CN112794715B, provides a method for multi-column deposition of carbon disks. Its main technology is to use natural gas, add propane and dilution gas nitrogen, and use graphite tooling piled around the outside of the carbon disk to reduce the internal tail gas residence space, thereby achieving back mixing to reduce the residence time of tail gas and improve the quality of deposited pyrolytic carbon. However, it cannot get rid of the carrier gas or dilution gas. It does not add a single-column graphite sleeve, but uses irregularly shaped graphite tooling surrounded in the furnace.

[0007] The existing patent, application number CN201510555712.4, proposes a method for depositing carbon discs with natural gas. It uses natural gas as the deposition gas and adopts a large volume deposition method. In addition, it proposes to control the generation rate of pyrolytic carbon during the deposition process. However, for multi-column (more than 3 columns) structures, it is difficult to achieve precise control in actual deposition process. Furthermore, the carbon source gas also needs to be a carrier gas or dilution gas.

[0008] Existing patent, application number CN202010243627.5, publication number CN111285703A, provides a multi-column method that uses a deposition process of propylene gas + propylene + dilution gas. However, to achieve multi-column deposition, each column must be isolated using a graphite cylinder as a separate deposition unit. Otherwise, multi-column deposition cannot be achieved. Furthermore, placing the graphite cylinders within the furnace is difficult when there are many charge columns. It also doesn't eliminate the concept of introducing carrier gas or dilution gas into the deposition zone, and it cannot directly deposit carbon disks to the required density (≥1.75 g / cm³). Instead, it requires subsequent resin densification to achieve the desired carbon disk density.

[0009] Therefore, increasing the furnace loading capacity, improving equipment efficiency, simplifying the control of the deposition process, preparing high-performance carbon disks, and developing more efficient deposition methods have always been challenging tasks. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a large-capacity carbon disc deposition device and its preparation method. Through complementary improvements to the deposition process and loading method, the carbon discs loaded into the deposition furnace can be deposited efficiently without complex furnace tooling. This significantly increases the inner diameter of the deposition furnace and the loading capacity, with a maximum capacity exceeding one thousand discs, thus meeting the needs of mass production. This method also simplifies the control of the deposition gas, eliminating the need to add inert diluent gas to suppress carbon black formation during deposition. This improves deposition efficiency and the precision of controlling the deposited carbon structure, significantly reducing production costs. Furthermore, this method allows achieving the required carbon disc density using only the deposition process.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A large-capacity carbon tray deposition equipment includes a deposition furnace, an air inlet assembly, and prefabricated components.

[0013] The deposition furnace is equipped with several heating elements arranged in a circular array, and a deposition chamber is provided inside the deposition furnace.

[0014] The air intake assembly includes a carbon source air intake pipe and a carrier gas air intake pipe, which are connected to the deposition chamber via pipes at the bottom of the deposition furnace.

[0015] The prefabricated workpiece is a cylindrical structure with its opening facing downwards and placed at the bottom of the deposition chamber. The deposition zone inside the prefabricated workpiece is covered by the carbon source inlet pipe, and the carrier gas inlet pipe is located outside the prefabricated workpiece. The deposition zone is connected to the deposition chamber through a vent hole on the prefabricated workpiece. The prefabricated workpiece includes a graphite base, a graphite cover plate, a prefabricated disk, and a regulator. The graphite base, prefabricated disk, and regulator are all annular structures. The graphite base, regulator, prefabricated disk, and graphite cover plate are stacked sequentially from bottom to top at the bottom of the deposition chamber, enclosing the deposition zone within it. The deposition zone is connected to the deposition chamber through a vent hole on the regulator. The vent is connected to the deposition chamber. The carbon source inlet pipe is located within and connected to the deposition zone. The carrier gas inlet pipe is located outside the graphite base and connected to the deposition chamber. The prefabricated discs and regulators each consist of several groups. Several regulators and prefabricated discs are stacked on the graphite base in pairs from bottom to top. The graphite cover plate covers the topmost prefabricated disc. The carbon source inlet pipe consists of a first inlet pipe, a second inlet pipe, a mixing tank, and a mixing pipeline. The first and second inlet pipes are respectively connected to the mixing tank. The mixing pipeline passes through the bottom of the deposition furnace and connects to the deposition zone.

[0016] The air intake assembly and the prefabricated workpiece each include several groups, and the prefabricated workpieces are distributed in a columnar shape in the deposition chamber. The air intake assembly corresponds one-to-one with the prefabricated workpiece.

[0017] This invention also provides a method for preparing a large-capacity carbon tray, comprising the following steps:

[0018] S1: Insert a graphite base onto the carbon source inlet pipe in the deposition chamber, stack several regulators and prefabricated discs in pairs on the graphite base from bottom to top, and finally cover the top prefabricated disc with a graphite cover plate to form a column of prefabricated workpiece.

[0019] S2: Several prefabricated workpieces stacked into a column shape are sequentially loaded into the deposition chamber, ensuring a distance between the columns;

[0020] S3: Set the temperature of the deposition furnace to 1000℃ and maintain a constant temperature throughout the deposition chamber;

[0021] S4: Natural gas is introduced into the first inlet pipe of each set of carbon source inlet pipes, and propylene or propane is introduced into the second inlet pipe. After being mixed and preheated in the mixing tank to form a mixed carbon source gas, it is introduced into the deposition zone inside the prefabricated workpiece covered by the mixing pipe at the bottom of the deposition furnace. The typical volume ratio of the flow rate of the first inlet pipe and the second inlet pipe of the carbon source gas is 70%~85%:30%~15%.

[0022] S5: After the carbon source gas has resided and reacted within the precast workpiece, the nitrogen or argon gas entering through the external carrier gas inlet pipe of the precast workpiece is carried away through the vent and discharged from the deposition chamber; the residence time τ refers to the time from when the flowing carbon source gas enters the deposition zone inside the precast workpiece until it completely detaches from the outer edge of the precast workpiece and is extracted, i.e., the allowable pyrolysis reaction time of the carbon source gas inside the precast workpiece, and its characterization formula is as follows:

[0023]

[0024] τ: Residence time of the carbon source gas in the deposition zone, in seconds;

[0025] V eff : The volume of the carbon source gas in the deposition zone, in liters (L);

[0026] P: Pressure of the carbon source gas in the deposition zone, in kPa;

[0027] Po: Gas pressure at the carbon source gas inlet, unit: kPa;

[0028] Q0: Flow rate of carbon source gas at the inlet, in L / min;

[0029] T0: Temperature at the carbon source gas inlet, in K;

[0030] T: Temperature of the sedimentation zone, in K;

[0031] S6: When the surface of the precast disc is crusted, its surface is processed and internal holes are made to turn the closed holes generated by pyrolysis carbon during deposition into open holes. The precast disc with the surface crust removed is then put back into the deposition furnace for deposition.

[0032] Compared with the prior art, the advantages of the present invention are as follows:

[0033] (1) There is no need to place graphite barrels for isolation and sealing between each column of precast workpieces, which can greatly increase the furnace loading capacity of the precast trays, improve equipment utilization, and significantly reduce costs. For the same size deposition chamber, the furnace loading capacity can be increased by more than 20% compared to the scheme with graphite barrels. It is only necessary to ensure a certain distance between the columns of precast workpieces. This furnace loading method does not require the inner diameter of each column of precast trays to be the same, which can allow different products to be loaded into the same furnace for deposition, improve production efficiency and product diversity, and also greatly simplify the operation of multi-column furnace loading and reduce labor intensity.

[0034] (2) No carrier gas / dilution gas is added to the carbon source gas during the deposition process, which is conducive to the conversion of the carbon source gas into pyrolytic carbon, to more precise control of the gas residence time, and to the generation of pyrolytic carbon with the required structure.

[0035] (3) By controlling the gas residence time more precisely, the texture of the deposited carbon can be controlled more precisely, the expected structure can be achieved, the performance of the precast disc is improved, the deposition efficiency is increased, and the production cost is reduced. In addition, the precast disc can be deposited to a higher density without the need for subsequent resin densification.

[0036] (4) Since the gas residence time of each precast workpiece can be controlled more precisely, precast discs of different sizes can be loaded into the same furnace, thus realizing the production of different products in the same furnace, achieving production flexibility and efficiency. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a perspective view of the internal layout of the deposition chamber of the present invention;

[0039] Figure 2 This is a cross-sectional view showing the internal arrangement of each prefabricated workpiece in this invention.

[0040] The components are: 1. Deposition furnace; 11. Heating element; 12. Deposition chamber; 2. Air inlet assembly; 21. Carbon source air inlet pipe; 211. First air inlet pipe; 212. Second air inlet pipe; 213. Mixing tank; 214. Mixing pipeline; 22. Carrier gas inlet pipe; 3. Precast workpiece; 31. Deposition zone; 32. Vent hole; 33. Graphite base; 34. Graphite cover plate; 35. Precast disc; 36. Regulator. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] The specific embodiments of the present invention will now be described with reference to the accompanying drawings:

[0043] Example 1: A large-capacity carbon tray deposition equipment, comprising a deposition furnace 1, an air inlet assembly 2, and a pre-formed workpiece 3.

[0044] The deposition furnace 1 is provided with a number of heating elements 11 arranged in a circular array inside, and the deposition furnace 1 is provided with a deposition chamber 12.

[0045] The air intake assembly 2 includes a carbon source air intake pipe 21 and a carrier gas air intake pipe 22, which are connected to the deposition chamber 12 through pipes at the bottom of the deposition furnace 1.

[0046] The prefabricated workpiece 3 is a cylindrical structure with its opening facing downwards and placed at the bottom of the deposition chamber 12. The deposition zone 31 inside the prefabricated workpiece 3 covers the carbon source inlet pipe 21. The carrier gas inlet pipe 22 is located outside the prefabricated workpiece 3. The deposition zone 31 is connected to the deposition chamber 12 through the vent hole 32 on the prefabricated workpiece 3. The prefabricated workpiece 3 includes a graphite base 33, a graphite cover plate 34, a prefabricated disk 35, and an regulator 36. The graphite base 33, the prefabricated disk 35, and the regulator 36 are all annular structures. The graphite base 33, the regulator 36, the prefabricated disk 35, and the graphite cover plate 34 are stacked sequentially from bottom to top at the bottom of the deposition chamber 12 and enclose the deposition zone 31 within it. The deposition zone 31 is connected to the deposition chamber 12 through the vent hole 32 on the regulator 36. The carbon source inlet pipe 21 is located within and connected to the deposition zone 31, and the carrier gas inlet pipe 22 is located outside the graphite base 33 and connected to the deposition chamber 12. The prefabricated plate 35 and the regulator 36 each include several groups. Several regulators 36 and prefabricated plates 35 are stacked on the graphite base 33 in pairs from bottom to top. The graphite cover plate 34 covers the topmost prefabricated plate 35. The carbon source inlet pipe 21 consists of a first inlet pipe 211, a second inlet pipe 212, a mixing tank 213, and a mixing pipe 214. The first inlet pipe 211 and the second inlet pipe 212 are respectively connected to the mixing tank 213. The mixing pipe 214 passes through the bottom of the deposition furnace 1 and is connected to the deposition zone 31.

[0047] The air intake assembly 2 and the prefabricated workpiece 3 each include several groups, and the prefabricated workpiece 3 is distributed in a columnar shape in the deposition chamber 12. The air intake assembly 2 corresponds one-to-one with the prefabricated workpiece 3.

[0048] The preparation method and steps of the large-capacity carbon tray of the present invention are as follows:

[0049] S1: Insert a graphite base 33 onto the carbon source inlet pipe 21 in the deposition chamber 12, stack several regulators 36 and prefabricated discs 35 in pairs from bottom to top on the graphite base 33, and finally cover the graphite cover plate 34 on the topmost prefabricated disc 35 to form a column of prefabricated workpiece 3.

[0050] S2: Several prefabricated workpieces 3 stacked into columnar shapes are sequentially loaded into the deposition chamber 12, ensuring a spacing between the columns;

[0051] S3: Set the temperature of the deposition furnace 1 to 1000℃ and maintain a constant temperature throughout the deposition chamber 12;

[0052] S4: Natural gas is introduced into the first inlet pipe 211 of each set of carbon source inlet pipes 21, and propylene or propane is introduced into the second inlet pipe 212. After being mixed and preheated into mixed carbon source gas in the mixing tank 213, it is introduced into the deposition zone 31 within the prefabricated workpiece 3 covered by the mixing pipe 214 at the bottom of the deposition furnace 1. The typical volume ratio of the flow rate of the first inlet pipe 211 and the second inlet pipe 212 of the carbon source gas is 70%~85%:30%~15%.

[0053] S5: After the carbon source gas has resided and reacted within the precast workpiece 3, the nitrogen or argon gas entering through the external carrier gas inlet pipe 22 of the precast workpiece 3 is carried away through the vent 32 and discharged from the deposition chamber 12; the residence time τ refers to the time from when the flowing carbon source gas enters the deposition zone 31 inside the precast workpiece 3 until it completely detaches from the outer edge of the precast workpiece 3 and is extracted, that is, the allowable pyrolysis reaction time of the carbon source gas inside the precast workpiece 3, and its characterization formula is as follows:

[0054]

[0055] τ: Residence time of the carbon source gas in deposition zone 31, in seconds;

[0056] V eff : This represents the volume of the carbon source gas in deposition zone 31, in liters (L).

[0057] P: Pressure of the carbon source gas in deposition zone 31, in kPa;

[0058] Po: Gas pressure at the carbon source gas inlet, unit: kPa;

[0059] Q0: Flow rate of carbon source gas at the inlet, in L / min;

[0060] T0: Temperature at the carbon source gas inlet, in K;

[0061] T: Temperature of the sedimentation zone at 31°C, in K;

[0062] S6: When the surface of the precast disc 35 is crusted, its surface is processed and internal holes are made to turn the closed holes generated by pyrolysis carbon during deposition into open holes. The precast disc 35 with the surface crust removed is then put back into the deposition furnace 1 for deposition.

[0063] Description of the working principle of this invention:

[0064] like Figure 1 As shown, the first inlet pipe 211 and the second inlet pipe 212 are for two source gases, which can be natural gas and propylene or natural gas and propane; the carrier gas inlet pipe 22 is for the tail gas, which can be nitrogen or argon; the mixing tank 213 is used to fully mix the two source gases and can heat the mixed gas to a certain temperature, and then introduce it into the deposition furnace 1 through the mixing pipe 214; the heating element 11 outside the deposition furnace 1 can raise the temperature of the entire deposition chamber 12 to above 1000°C and keep the entire deposition chamber 12 at a constant temperature; all columnar preforms 3 are placed in the deposition chamber 12 for deposition, the deposition area 31 inside the preform 3 is connected to the carbon source inlet pipe 21, and the carrier gas inlet pipe 22 is located outside the preform 3. The upper part of the deposition furnace 1 has an opening that communicates with the deposition chamber 12. The exhaust pipe is designed to maintain high temperature and vacuum inside the deposition furnace 1. The carrier gas introduced by the carrier gas inlet pipe 22 will discharge the exhaust gas after the reaction through the exhaust pipe. This is existing technology, so the exhaust pipe will not be shown in the attached figures and descriptions of this article, nor will its implementation be described in detail. Several pre-made workpieces 3 are arranged in columns in the deposition chamber 12. Each column holds a pre-made plate 35 with the same inner and outer diameter. The pre-made plate 35 is the carbon plate. In the deposition chamber 12, each column of pre-made workpieces 3 has a separate carbon source inlet pipe 21 below it, which provides carbon source gas only to the pre-made workpiece 3 of that column. The flow rate of the gas is adjustable. Similarly, each column of pre-made workpieces 3 is also provided with one or more sets of carrier gas inlet pipes 22 arranged in a circular pattern. They are not shared with other columns, and their flow rates are also adjustable.

[0065] The arrangement diagram of each prefabricated workpiece 3 inside the deposition chamber 12 is shown below. Figure 2As shown, the heated mixed carbon source gas is directly introduced into the deposition zone 31 of the precast workpiece 3 through the mixing pipe 214. The precast workpiece 3 contains, from bottom to top, a graphite base 33, a regulator 36, a precast disc 35, and a graphite cover plate 34. The regulator 36 and the precast disc 35 are grouped in pairs and can be stacked in several groups. The regulator 36 is a customized tooling. Since the precast disc 35 of each column of precast workpiece 3 is different, the size of the regulator 36 used in each column is different. The structure of the regulator 36 is a customized thickness plate with ventilation holes 32. By changing the thickness of the plate and the size of the ventilation holes, the gas space and gas flow rate inside the deposition workpiece can be controlled.

[0066] The carbon disk deposition process is as follows:

[0067] Several prefabricated workpieces 3 are loaded into the deposition chamber 12 of the deposition furnace 1, with a certain spacing between the columns. This loading method does not require the inner diameter of the prefabricated disc 35 of each column of prefabricated workpieces 3 to be the same. Only prefabricated discs 35 of the same specification need to be stacked in the same prefabricated workpiece 3, so that different products can be loaded into the same deposition furnace 1 for deposition. This improves production efficiency and product diversity. Since there is no need to use a graphite sleeve to isolate each column of prefabricated workpieces 3, the complexity of loading is greatly simplified, the labor intensity of loading is greatly reduced, and the loading capacity of each furnace is increased. It is suitable for mass production of carbon discs.

[0068] When placing each precast disc 35, the precast disc 35 is placed on the graphite base 33. An regulator 36 is installed between each precast disc 35. The function of the regulator 36 is to adjust the carbon source gas space and gas concentration inside the precast disc 35 and to prevent the back mixing of tail gas caused by deposition.

[0069] The gases from the first intake pipe 211 and the second intake pipe 212 are mixed and preheated in the gas mixing tank 213. The preheating temperature is controlled at 100℃~300℃. After forming carbon source gas, it is introduced into the deposition zone 31 of the precast workpiece 3 in the deposition chamber 12 of the deposition furnace 1 through the gas mixing pipe 214 below the deposition furnace 1.

[0070] During the deposition process, the thermal decomposition of the carbon source gas into carbon generates a series of intermediates. Some of these intermediates are converted into pyrolytic carbon, but most are converted into other types of organic molecules, such as ethylene, acetylene, and aromatics. Therefore, a large number of byproducts will appear during the deposition process. These byproducts are the tail gas in the deposition process. Their presence inside the precast workpiece 3 is harmful and needs to be removed.

[0071] In this method, the two source gases, natural gas and propylene (propane), can theoretically be directly and independently generated into pyrolytic carbon at high temperatures. However, in this method, the two source gases are not directly introduced into the pre-made workpiece 3 for direct cracking into pyrolytic carbon. Instead, they are first introduced into the mixing tank 213 for thorough mixing and preheating.

[0072] If the gas is directly introduced, at a high temperature of nearly 1000℃, the two source gases with different molecular structures will undergo cracking and deposition reactions on their own, resulting in the generation of pyrolytic carbon with different structural states. As a result, isotropic carbon, rough layer structure carbon, and smooth layer structure carbon may be generated, and these types of carbon exhibit different tribological properties.

[0073] Therefore, allowing the two source gases to react independently will produce carbon matrices with various complex structures, which is not what is desired in the production of carbon discs. The more ideal situation is to generate pyrolytic carbon with a single structure (such as pyrolytic carbon with a rough layer structure). In this case, controlling the reaction is a more complex matter. However, it is much easier to control the generation of pyrolytic carbon with a single structure by fully mixing and heating the source gases to form the carbon source gas.

[0074] The carrier gas used to suppress the formation of carbon black in the exhaust gas does not participate in the reaction. Instead, it carries away the exhaust gas generated by the pyrolysis reaction that has not participated in the deposition through the vent 32 from the outside of the precast workpiece 3.

[0075] The preheated carbon source gas is guided by the mixing pipe 214 to the deposition area 31 of the precast workpiece 3. This guidance can achieve full diffusion of the carbon source gas inside the precast workpiece 3. At this time, only the mixed carbon source gas generated by the two source gases is introduced into the deposition of the precast workpiece 3, without carrier gas or dilution gas.

[0076] During the deposition process of precast workpiece 3, the carbon source gas is constantly flowing. Carbon source gas is continuously input into the interior of precast workpiece 3, and after a short period of time, it undergoes a high-temperature pyrolysis reaction. Then, the unreacted gas and the intermediates produced by the reaction are continuously extracted from precast workpiece 3 and discharged as exhaust gas by the carrier gas, thus achieving a kind of dynamic equilibrium deposition gas pyrolysis reaction.

[0077] The mixed carbon source gas enters the interior of the preform 3 and undergoes a complex reaction involving cracking and deposition of pyrolytic carbon, thus generating pyrolytic carbon. The biggest difference between this method and other methods is that the carbon source gas entering the preform 3 does not contain an inert diluent gas. Therefore, the control of the reaction must be extremely precise. Otherwise, if the carbon source gas remains in the preform 3 for too long, a large amount of gaseous carbon black will easily be generated in the internal space of the preform 3, leading to deposition failure. If the carbon source gas remains in the preform 3 for too short a time, the pyrolytic carbon generation rate will be too low, and the desired pyrolytic carbon structure will not be obtained. The key control point of this method is the carbon source gas residence time τ.

[0078] Residence time τ refers to the time from when the flowing carbon source gas enters the deposition zone 31 inside the precast workpiece 3 until it completely leaves the outer edge of the precast workpiece 3 and is pumped away. It is the allowable pyrolysis reaction time of the carbon source gas inside the precast workpiece 3, and its characterization formula is as follows:

[0079]

[0080] τ: Residence time of the carbon source gas in deposition zone 31, in seconds;

[0081] V eff : This is the volume of the carbon source gas in the deposition zone 31, in L, which is the volume of the middle part of each group of prefabricated discs 35, and the sum of the volumes of the middle parts of each group of regulators 36.

[0082] P: Pressure of the carbon source gas in deposition zone 31, in kPa;

[0083] Po: Gas pressure at the carbon source gas inlet, unit: kPa;

[0084] Q0: Flow rate of carbon source gas at the inlet, in L / min;

[0085] T0: Temperature at the carbon source gas inlet, in K;

[0086] T: Temperature of the deposition zone, in K.

[0087] Studies have found that by combining and coarsely controlling the above parameters, the residence time τ can be controlled within the range of 1.0 to 5.0 s. At this range, the deposition efficiency is optimal, and the generated pyrolytic carbon is predominantly a rough layer. If the residence time τ is too short, it hinders the deposition rate, resulting in a predominantly isotropic layer of pyrolytic carbon. Furthermore, the workpiece weight gain is too slow, and the quality of the pyrolytic carbon deteriorates. If the residence time τ is too long, the quality of the deposited carbon deteriorates, resulting in a predominantly smooth layer, and the gas-phase reaction increases, making it easier to produce carbon black.

[0088] Excessive carbon source gas and various olefins and aromatics generated during the reaction inside the precast workpiece 3 will be extracted from the precast workpiece 3 through the vent 32 and carried away by the carrier gas blown out by the carrier gas inlet pipe 22 arranged on the outside of the precast workpiece 3. The tail gas carrier gas, which is not shared with other columns, is distributed in several sets of circumferential vent holes, which are used to vent gas out of the precast workpiece 3 column in an annular manner. Since the deposition chamber 12 is in a near-vacuum state during deposition, the gas flow direction is directional along the carrier gas inlet pipe 22 to the exhaust pipe until it is discharged from the deposition chamber 12, so as to avoid back mixing and the generation of carbon black. In addition, it is also to avoid interfering with the deposition reaction of other workpiece columns.

[0089] When deposited at a higher density (carbon disk density ≥ 1.63 g / cm³)3 When the surface reaction of the precast disc 35 increases, it is prone to forming a crust. At this time, the surface will be processed and internal pores will be opened to turn the closed pores formed by pyrolysis carbon during deposition into open pores, which is conducive to further increasing the deposition density of the precast disc 35. The precast disc 35 with the surface crust removed is put back into the deposition furnace 1 for deposition until the carbon disc density is ≥1.75 g / cm³. 3 .

[0090] The carbon disks produced by the above deposition process have a predominantly rough texture and a secondary smooth texture.

[0091] Example 2:

[0092] 1. After stacking the precast disc 35 and regulator 36 after high-temperature treatment to form the precast workpiece 3, it is divided into multiple columns and loaded into the deposition furnace 1. The internal space V of each column is calculated. eff The internal space of each precast workpiece 3 can be adjusted by the regulator 36. The diameter of the deposition chamber 12 in the deposition furnace 1 is greater than 3 meters. Each furnace can hold more than a dozen columns and can hold precast workpieces of different diameters.

[0093] 2. Heat the sedimentation chamber 12 to approximately 1000℃ and maintain a uniform temperature.

[0094] 3. Carbon source gas is introduced into each precast workpiece 3. The first inlet pipe 211 is for natural gas, and the second inlet pipe 212 is for propylene. The typical flow rate to volume ratio is approximately 85%:15%. The flow rate of the carbon source gas introduced into each precast workpiece 3 varies with the total volume of the workpiece, and one typical flow rate is approximately 20~30 L / min. During deposition, the carrier gas for the tail gas is introduced, with a flow rate of approximately 15~20 L / min.

[0095] 4. After ventilation, the temperature and gas flow rate of the sedimentation zone 31 are further precisely adjusted. The adjustment parameters are as follows: carbon source gas inlet flow rate Q0, carbon source gas inlet temperature T0, sedimentation zone 31 temperature T, and carbon source gas pressure P in sedimentation zone 31. After controlling the changes of the above parameters, the residence time of the carbon source gas is between 1 and 3 seconds.

[0096] 5. During deposition, maintain the pressure inside deposition furnace 1 at approximately 1~3 kPa.

[0097] 6. After every 200-300 hours of deposition, cool the furnace, remove the precast tray 35, adjust its placement, and re-deposit until the density of the precast tray 35 reaches 1.65 or higher. Then, machine it, peel off the surface crust layer, perform high-temperature drilling, and re-deposit it in the deposition furnace 1 until it reaches 1.75 or higher.

[0098] Example 3 differs from Example 2 in that:

[0099] The first intake pipe 211 carries natural gas, and the second intake pipe 212 carries propane, with a typical flow rate volume ratio of approximately 70%:30%.

[0100] The beneficial effects of this invention are as follows:

[0101] (1) There is no need to place graphite barrels for isolation and sealing between each column of precast workpiece 3, which can greatly increase the furnace loading capacity of the precast plate 35, improve equipment utilization, and significantly reduce costs. For the same size deposition chamber 12, the furnace loading capacity can be increased by more than 20% compared with the scheme of adding graphite barrels. It is only necessary to ensure a certain distance between the columns of precast workpiece 3. This furnace loading method does not require the inner diameter of each column of precast plate 35 to be the same, which can allow different products to be loaded into the same furnace for deposition, improve production efficiency and product production diversity, and greatly simplify the operation difficulty of multi-column furnace loading and reduce labor intensity.

[0102] (2) No carrier gas / dilution gas is added to the carbon source gas during the deposition process, which is conducive to the conversion of the carbon source gas into pyrolytic carbon, to more precise control of the gas residence time, and to the generation of pyrolytic carbon with the required structure.

[0103] (3) By controlling the gas residence time more precisely, the texture of the deposited carbon can be controlled more precisely, the expected structure can be achieved, the performance of the precast plate 35 is improved, the deposition efficiency is increased, the production cost is reduced, and the precast plate 35 can be deposited to a higher density without the need for subsequent resin densification.

[0104] (4) Since the gas residence time of each precast workpiece 3 can be controlled more precisely, precast discs 35 of different sizes can be loaded into the same furnace, so that different types of products can be produced in the same furnace, realizing the flexibility and efficiency of production.

[0105] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large-capacity carbon tray deposition device, characterized in that: Includes deposition furnace, air intake assembly, and prefabricated parts; The deposition furnace is equipped with several heating elements arranged in a circular array inside, and a deposition chamber is provided inside the deposition furnace; The air intake assembly includes a carbon source air intake pipe and a carrier gas air intake pipe, which are respectively connected to the deposition chamber through pipes at the bottom of the deposition furnace. The prefabricated workpiece is a cylindrical structure with its opening facing downward and placed at the bottom of the deposition chamber. The deposition area inside the prefabricated workpiece is covered by the carbon source inlet pipe. The carrier gas inlet pipe is located outside the prefabricated workpiece. The deposition area is connected to the deposition chamber through the vent on the prefabricated workpiece. The carbon source inlet pipe consists of a first inlet pipe, a second inlet pipe, a mixing tank, and a mixing pipeline. The first inlet pipe and the second inlet pipe are respectively connected to the mixing tank, and the mixing pipeline passes through the bottom of the deposition furnace and is connected to the deposition zone. Natural gas is introduced into the first inlet pipe of each set of carbon source inlet pipes, and propylene or propane is introduced into the second inlet pipe. After being mixed and preheated into mixed carbon source gas in the mixing tank, it is introduced into the deposition zone inside the prefabricated workpiece covered by the mixing pipe at the bottom of the deposition furnace. After the carbon source gas has been in the precast workpiece for a period of time and reacted, the nitrogen or argon gas that enters through the external carrier gas inlet pipe of the precast workpiece is carried away through the vent and discharged from the deposition chamber.

2. The large-capacity carbon tray deposition equipment according to claim 1, characterized in that: The prefabricated workpiece includes a graphite base, a graphite cover plate, a prefabricated disc, and a regulator. The graphite base, prefabricated disc, and regulator are all ring-shaped structures. The graphite base, regulator, prefabricated disc, and graphite cover plate are stacked sequentially from bottom to top at the bottom of the deposition chamber and enclose a deposition area therein. The deposition area is connected to the deposition chamber through a vent on the regulator. The carbon source inlet pipe is located inside the deposition area and is connected to the deposition area. The carrier gas inlet pipe is located outside the graphite base and is connected to the deposition chamber.

3. The large-capacity carbon tray deposition equipment according to claim 2, characterized in that: The prefabricated discs and regulators each comprise several groups, and several regulators and prefabricated discs are stacked in pairs on the graphite base from bottom to top, with the graphite cover plate covering the topmost prefabricated disc.

4. The large-capacity carbon tray deposition equipment according to claim 3, characterized in that: The air intake assembly and the prefabricated workpiece each include several groups, and the prefabricated workpieces are distributed in a columnar shape in the deposition chamber. The air intake assembly corresponds one-to-one with the prefabricated workpiece.

5. A method for preparing a large-capacity carbon tray, based on the large-capacity carbon tray deposition equipment according to any one of claims 2-4, characterized in that, It includes the following specific steps: S1: Insert a graphite base onto the carbon source inlet pipe in the deposition chamber, stack several regulators and prefabricated discs in pairs on the graphite base from bottom to top, and finally cover the top prefabricated disc with a graphite cover plate to form a column of prefabricated workpiece. S2: Several prefabricated workpieces stacked into a column shape are sequentially loaded into the deposition chamber, ensuring a distance between the columns; S3: Heats up the deposition furnace and maintains a constant temperature throughout the deposition chamber; S4: Natural gas is introduced into the first inlet pipe of each set of carbon source inlet pipes, and propylene or propane is introduced into the second inlet pipe. After being mixed and preheated into mixed carbon source gas in the mixing tank, it is introduced into the deposition zone inside the prefabricated workpiece covered by the mixing pipe at the bottom of the deposition furnace. S5: After the carbon source gas has been in the precast workpiece for a period of time and reacted, the nitrogen or argon gas that enters through the precast workpiece external carrier gas inlet pipe is carried away through the vent and discharged from the deposition chamber.

6. The method for preparing a large-capacity carbon tray according to claim 5, characterized in that: It also includes S6: When the surface of the precast disc is crusted, its surface is processed and internal holes are made to turn the closed holes generated by pyrolysis carbon during deposition into open holes. The precast disc with the surface crust removed is then put back into the deposition furnace for deposition.

7. The method for preparing a large-capacity carbon tray according to claim 5, characterized in that: In S3, the deposition furnace is heated to 1000°C.

8. The method for preparing a large-capacity carbon tray according to claim 5, characterized in that: In S4, the volume ratio of the flow rate of the first inlet pipe and the second inlet pipe of the carbon source gas is 70%~85%:30%~15%.

9. The method for preparing a large-capacity carbon tray according to claim 8, characterized in that: In S5, the residence time τ refers to the time from when the flowing carbon source gas enters the deposition zone inside the preform until it completely detaches from the outer edge of the preform and is extracted, i.e., the allowable pyrolysis reaction time of the carbon source gas inside the preform. Its characterization formula is as follows: ； τ: Residence time of the carbon source gas in the deposition zone, in seconds; V eff : The volume of the carbon source gas in the deposition zone, in liters (L); P: Pressure of the carbon source gas in the deposition zone, in kPa; Po: Gas pressure at the carbon source gas inlet, unit: kPa; Q0: Flow rate of carbon source gas at the inlet, in L / min; T0: Temperature at the carbon source gas inlet, in K; T: Temperature of the deposition zone, in K.

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