Carbon-carbon composite cylinder and its preparation method and application

Abstract

This application provides a carbon-carbon composite cylinder, its preparation method, and its application. The preparation method includes: impregnating carbon fiber filaments with a resin solution to obtain resin-impregnated carbon fibers with a resin solution volume content of 15%~20%; forming a cylindrical wound body from the resin-impregnated carbon fibers using a wet winding process; wherein the winding method of the resin-impregnated carbon fibers in the wet winding process involves alternating longitudinal planar winding, circumferential planar winding, and helical winding; curing the cylindrical wound body to obtain a resin-based composite material preform; placing the preform in a chemical vapor deposition (CVD) apparatus for initial carbonization and CVD densification to obtain a carbon-carbon composite material preform; sequentially subjecting the preform to machining, impregnation for carbonization densification, and graphitization to obtain a carbon-carbon composite material semi-finished product; and preparing a surface pyrolytic carbon layer after machining and surface polishing of the semi-finished product. This carbon-carbon composite cylinder exhibits high strength and a long service life.

Description

Technical Field

[0001] This application relates to the field of carbon-carbon composite materials technology, and in particular to a carbon-carbon composite material cylinder, its preparation method, and its application. Background Technology

[0002] Carbon-carbon composite materials, as one of the few candidate materials that can be used normally in an inert gas protective atmosphere exceeding 1800℃, are widely used in many industries due to their advantages such as high specific strength, high specific modulus, wear resistance, fatigue resistance, corrosion resistance, high temperature resistance, and strong thermal shock resistance. They are also gradually being introduced into the field of high-temperature and high-pressure sintering of special ceramics.

[0003] In the field of hot pressing sintering for special ceramics, carbon-carbon composite hot pressing molds are typically used to prepare carbon fiber preforms through three-dimensional weaving, followed by densification and graphitization treatments to obtain the finished product. Common densification processes include chemical vapor deposition and liquid-phase impregnation carbonization. However, due to the relatively thick walls of the hot pressing molds for special ceramics, often exceeding 100mm, densification is difficult, resulting in high internal porosity and numerous internal defects, leading to a short service life. Furthermore, the 2.5d needle punching process, commonly used in carbon-carbon composite material preparation, causes significant damage to the carbon fibers, and its mechanical properties cannot meet the requirements for carbon-carbon hot pressing molds used in the field of hot pressing sintering for special ceramics.

[0004] Currently, among the technologies for preparing carbon-carbon composite materials through carbon fiber winding, resin-based composite materials are the primary focus, and are commonly used for preparing thin-walled products. When preparing thick-walled carbon-carbon composite cylinders, the preparation of carbon-carbon composite materials must involve processes such as carbonization and graphitization. After preparing thick-walled resin-based composite materials using conventional winding processes, subsequent carbonization will result in significant expansion, cracking, and delamination problems, making it virtually impossible to obtain carbon-carbon hot pressing molds that meet the requirements for use.

[0005] Therefore, developing a method for preparing high-strength, long-service carbon-carbon composite cylindrical products to meet the performance requirements of hot pressing molds in the field of high-temperature and high-pressure sintering of special ceramics has become one of the important research directions in this field. Summary of the Invention

[0006] Based on this, this application provides a carbon-carbon composite material cylinder, its preparation method and application. The carbon-carbon composite material cylinder has high strength and long service life, which can better meet the performance requirements of carbon-carbon hot pressing molds in the field of special ceramic hot pressing sintering.

[0007] The technical solution proposed in this application is as follows:

[0008] According to a first aspect of this application, a method for preparing a carbon-carbon composite material cylinder is provided, comprising the following steps:

[0009] Impregnating carbon fiber filaments with a wetting solution yields adhesive-coated carbon fibers with a volume content of 15% to 20%.

[0010] The adhesive-coated carbon fiber is made into a cylindrical wound body by a wet winding process; in the wet winding process, the adhesive-coated carbon fiber is wound in a combination of longitudinal planar winding, circumferential planar winding and helical winding.

[0011] The cylindrical winding body is cured to obtain a resin-based composite material blank.

[0012] The resin-based composite material blank is placed in a chemical vapor deposition (CVD) apparatus for initial carbonization and CVD densification to obtain a carbon-carbon composite material blank.

[0013] The carbon-carbon composite material blank is sequentially subjected to machining, impregnation carbonization densification treatment and graphitization treatment to obtain a carbon-carbon composite material semi-finished product;

[0014] After mechanical processing and surface polishing, the carbon-carbon composite material semi-finished product is used to prepare a surface pyrolytic carbon layer, thereby obtaining the carbon-carbon composite material cylinder.

[0015] The above-mentioned preparation method controls the volume content of the adhesive solution after impregnating the carbon fiber filaments to 15%~20%, and uses a wet winding process to prepare a cylindrical winding body. In the wet winding process, the winding method of the adhesive-coated carbon fiber is carried out by alternating longitudinal planar winding, circumferential planar winding, and helical winding. While ensuring the stability of the yarn in the cylindrical winding body, it solves the problem of yarn delamination caused by resin curing and degassing in conventional winding processes. Furthermore, the lower volume content of adhesive solution on the adhesive-coated carbon fiber helps to reduce the generation of volatile substances during subsequent curing, which helps to reduce the internal stress of the product and maintain the structural stability of the cylindrical winding body in subsequent processes.

[0016] Completing the initial carbonization and chemical vapor deposition (CVD) densification processes in the same furnace within a CVD apparatus allows for the timely introduction of a carbon source after the initial carbonization for densification. This effectively fills voids and delamination caused by the volatilization of non-carbonaceous substances in the cured component, further ensuring the product's density and low damage rate. By combining controlled adhesive volume content of the bonded carbon fiber, wet winding methods, and the simultaneous completion of the initial carbonization and CVD densification processes, this method produces carbon-carbon composite cylinders with high strength and long service life, effectively meeting the performance requirements of carbon-carbon hot-pressing molds in the field of special ceramic hot-pressing sintering.

[0017] In some embodiments, the impregnation solution comprises the following components by weight: 1 to 2 parts anhydrous ethanol, 1 to 2 parts phenolic resin, and 0.001 to 0.002 parts silane coupling agent.

[0018] In some embodiments, the wet winding process includes the following steps:

[0019] The adhesive-coated carbon fiber is wound onto the mandrel in a longitudinal planar winding manner to complete the first layer of winding, then wound in a circumferential planar winding manner to complete the second layer of winding, and then wound in a spiral winding manner to complete the third layer of winding.

[0020] After completing the third layer of winding, the adhesive carbon fiber is wound 100 to 150 times in sequence, consisting of one layer of longitudinal planar winding, one layer of circumferential planar winding, and one layer of spiral winding.

[0021] One layer of longitudinal planar winding and nine layers of circumferential planar winding are performed sequentially as one winding cycle, and the adhesive-coated carbon fiber is repeatedly wound for 150 to 200 cycles.

[0022] The adhesive-coated carbon fiber is wound in sequence with one layer of longitudinal planar winding, one layer of circumferential planar winding, and one layer of spiral winding as one winding cycle, and the winding cycle is repeated 100 to 150 times.

[0023] In some embodiments, the tension of the first layer of the wet winding process is 1100N~1500N, and the winding tension decreases layer by layer as the number of winding layers increases, with the tension of the last layer being 100N~150N.

[0024] In some embodiments, the curing process includes the following steps: placing the cylindrical winding body and the mandrel together in a curing oven, and heating and curing the cylindrical winding body while rotating. The curing process is as follows: curing at room temperature to 100°C for 190 min to 210 min, curing at 100°C for 490 min to 510 min, curing at 100°C to 150°C for 390 min to 410 min, curing at 150°C for 490 min to 510 min, curing at 150°C to 220°C for 180 min to 220 min, and curing at 220°C for 490 min to 510 min.

[0025] In some embodiments, the initial carbonization treatment and chemical vapor deposition (CVD) densification treatment include the following steps: placing the resin-based composite material preform in a CVD apparatus and treating it according to the following procedure: treating at room temperature to 200°C under nitrogen protection and constant pressure of 2.0 MPa to 3.0 MPa for 500 min to 530 min; treating at 200°C under nitrogen protection and constant pressure of 2.0 MPa to 3.0 MPa for 90 min to 120 min; and treating at 200°C to 600°C under nitrogen protection and constant pressure of 2.0 MPa to 3.0 MPa for 200 min to 240 min. Treatment at 600℃ under constant temperature and nitrogen protection at a constant pressure of 2.0MPa~3.0MPa for 300~360 min; treatment at 600℃~800℃ under vacuum to within 50Pa for 240~300 min; treatment at 800℃~1300℃ under continuous introduction of carbon source gas and nitrogen, and furnace pressure of 5000Pa~8000Pa for 200~280 min; treatment at 1300℃ under constant temperature and continuous introduction of carbon source gas and nitrogen, and furnace pressure of 5000Pa~8000Pa for 6000~10000 min.

[0026] In some embodiments, the impregnation carbonization densification process includes the following steps:

[0027] The carbon-carbon composite material blank is placed in an impregnation furnace, and phenolic resin is filled in under vacuum. It is left to stand for 4 to 5 hours. Nitrogen gas is then introduced to a pressure of 4 MPa to 5 MPa, and the pressure is maintained for 8 to 10 hours to complete the impregnation.

[0028] Drain the resin liquid from the impregnation furnace and evacuate to 50 kPa~80 kPa; treat at room temperature to 80℃ and furnace pressure of 50 kPa~80 kPa for 95 min~105 min; maintain a constant temperature of 80℃ and furnace pressure of 50 kPa~80 kPa for 55 min~65 min; treat at 80℃~180℃ and furnace pressure of 50 kPa~80 kPa for 195 min~205 min; maintain a constant temperature of 180℃ and furnace pressure of 100 kPa~200 kPa for 495 min~505 min.

[0029] According to a second aspect of this application, a carbon-carbon composite material cylinder is provided, which is prepared by the method for preparing a carbon-carbon composite material cylinder according to the first aspect of this application.

[0030] In some embodiments, the wall thickness of the carbon-carbon composite cylinder is 100mm to 200mm.

[0031] According to a third aspect of this application, an application of the carbon-carbon composite material cylinder of the first aspect of this application in the hot pressing sintering of special ceramics is provided. Attached Figure Description

[0032] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 This is a flowchart illustrating a method for preparing a carbon-carbon composite material cylinder according to an embodiment of this application. Detailed Implementation

[0034] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0035] The "range" disclosed in this application can be defined in the form of 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. Any endpoint can be independently included or excluded, and they can be combined arbitrarily; 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 expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are also 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 numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this document; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, stating that a parameter is an integer ≥2 is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, stating that a parameter is an integer selected from "2~10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0036] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0037] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0039] Those skilled in the art will understand that the order in which the steps are written in the methods of various embodiments or examples does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0040] In this application, unless otherwise specified, A (e.g., B) means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0041] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0042] Traditional three-dimensional braiding molding processes face challenges in densifying carbon-carbon composite cylinders with thick walls (over 100mm), resulting in high internal porosity, numerous internal defects, and consequently, short product lifespan. When using conventional winding processes to prepare carbon-carbon composite cylinders, significant expansion, cracking, and delamination occur during the carbonization process following the preparation of thick-walled resin-based composites. Consequently, the resulting products fail to meet the performance requirements of carbon-carbon hot-pressing molds in the field of special ceramic hot-pressing sintering.

[0043] For this, please refer to Figure 1 One embodiment of this application provides a method for preparing a carbon-carbon composite material cylinder, the method comprising the following steps S100 to S600:

[0044] Step S100: Impregnate the carbon fiber filament with the adhesive solution to obtain adhesive-coated carbon fiber with an adhesive volume content of 15%~20%.

[0045] Step S200: The adhesive-coated carbon fiber is made into a cylindrical winding body by a wet winding process; the winding method of the adhesive-coated carbon fiber in the wet winding process is a combination of longitudinal planar winding, circumferential planar winding and helical winding.

[0046] Step S300: The cylindrical winding body is cured to obtain a resin-based composite material blank.

[0047] Step S400: The resin-based composite material blank is placed in a chemical vapor deposition (CVD) device for initial carbonization and CVD densification to obtain a carbon-carbon composite material blank.

[0048] Step S500: The carbon-carbon composite material blank is subjected to machining, impregnation carbonization densification treatment and graphitization treatment in sequence to obtain carbon-carbon composite material semi-finished product.

[0049] Step S600: After machining and surface polishing, a surface pyrolytic carbon layer is prepared to obtain a carbon-carbon composite cylinder.

[0050] In the preparation method described above in this application, the volume content of the adhesive solution after impregnating the carbon fiber filaments is controlled at 15% to 20%, and a tubular winding body is prepared by a wet winding process. In the wet winding process, the winding method of the adhesive-coated carbon fiber is carried out by alternating longitudinal planar winding, circumferential planar winding, and helical winding. While ensuring the stability of the yarn in the tubular winding body, the problem of yarn delamination caused by resin curing and degassing in conventional winding processes is solved. Furthermore, the lower volume content of adhesive solution on the adhesive-coated carbon fiber is beneficial to reducing the generation of volatile substances during subsequent curing, which is beneficial to reducing the internal stress of the product and maintaining the structural stability of the tubular winding body in subsequent processes.

[0051] Furthermore, completing the initial carbonization and chemical vapor deposition (CVD) densification processes in the same furnace within a CVD apparatus allows for the timely introduction of a carbon source after the initial carbonization process. This effectively fills voids and delamination caused by the volatilization of non-carbonaceous substances in the cured component, further ensuring the product's density and low damage rate. By combining controlled adhesive volume content of the bonded carbon fiber, wet winding methods, and the simultaneous completion of the initial carbonization and CVD densification processes, the carbon-carbon composite cylinder prepared using this method exhibits high strength and a long service life, effectively meeting the performance requirements of carbon-carbon hot-pressing molds in the field of special ceramic hot-pressing sintering.

[0052] It should be noted that the main difference between longitudinal planar winding, circumferential planar winding, and helical winding in yarn winding processes lies in the winding angle and trajectory plane of the yarn relative to the substrate (such as a mandrel). Longitudinal planar winding, also known as "polar winding" or "meridian winding," is a winding method in which the yarn forms a trajectory in a longitudinal plane along the axis of the substrate. Circumferential planar winding, also known as "circumferential winding," is a winding method in which the yarn forms a trajectory in a plane perpendicular to the axis along the circumference of the substrate. Helical winding, also known as "oblique winding," is a winding method in which the yarn forms a helical trajectory along the surface of the substrate at an angle between longitudinal and circumferential (usually 15°~85°).

[0053] Understandably, the volume content of the adhesive liquid on the adhesive-coated carbon fiber in this application can be 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, or any value within the range formed by any two of the above values.

[0054] In some embodiments, the impregnation solution comprises the following components by weight: 1 to 2 parts anhydrous ethanol, 1 to 2 parts phenolic resin, and 0.001 to 0.002 parts silane coupling agent. Anhydrous ethanol is used as a solvent to dissolve and dilute the phenolic resin, and the purity of the anhydrous ethanol is greater than or equal to 98%. The phenolic resin can be a thermosetting boron-modified phenolic resin solution with a solid content ≥80% and residual carbon ≥55%. The silane coupling agent can be γ-aminopropyltriethoxysilane. The above impregnation solution is prepared in an environment with a constant temperature of 25°C and a constant humidity of 40%.

[0055] In some embodiments, the carbon fiber filaments can be 12K or 24K polyacrylonitrile-based carbon fibers with a T700 grade or higher. Here, 12K and 24K refer to the number of monofilaments contained in the carbon fiber bundle; 1K represents 1000 monofilaments in a bundle, therefore a 12K carbon fiber bundle contains 12000 monofilaments, and a 24K carbon fiber bundle contains 24000 monofilaments. A T700 grade or higher polyacrylonitrile-based carbon fiber indicates that the tensile strength of the carbon fiber reaches 700 MPa or higher, classifying it as a high-performance carbon fiber.

[0056] In some embodiments, the wet winding process includes the following steps:

[0057] The adhesive-coated carbon fiber is wound onto the mandrel in a longitudinal planar manner to complete the first layer of winding, then wound in a circumferential planar manner to complete the second layer of winding, and finally wound in a helical manner to complete the third layer of winding.

[0058] After completing the third layer of winding, the adhesive-coated carbon fiber is wound 100 to 150 times in sequence as one layer of longitudinal planar winding, one layer of circumferential planar winding, and one layer of spiral winding.

[0059] One layer of longitudinal planar winding and nine layers of circumferential planar winding are performed sequentially as one winding cycle, and the adhesive-coated carbon fiber is repeatedly wound for 150 to 200 cycles.

[0060] One layer of longitudinal planar winding, one layer of circumferential planar winding, and one layer of helical winding are performed sequentially as one winding cycle. The adhesive-coated carbon fiber is repeatedly wound for 100 to 150 cycles.

[0061] Thus, the adhesive-coated carbon fiber is first wound sequentially in a longitudinal plane, then in a circumferential plane, and finally in a spiral to form the first, second, and third layers of winding, respectively. Then, a winding cycle is performed with one layer of longitudinal plane winding, one layer of circumferential plane winding, and one layer of spiral winding, repeated 100-150 times. Next, a winding cycle is performed with one layer of longitudinal plane winding and nine layers of circumferential plane winding, repeated 150-200 times. Finally, a winding cycle is performed with one layer of longitudinal plane winding, one layer of circumferential plane winding, and one layer of spiral winding, repeated 100-150 times to prepare a tubular wound body. This specific wet winding process helps ensure the stability of the yarn in the finished product, solves the yarn delamination problem caused by resin curing and venting, and helps maintain the structural stability of the tubular wound body in subsequent processes, thereby improving the product's strength and service life.

[0062] In some embodiments, the tension of the first layer in the wet winding process is 1100N~1500N, and the winding tension decreases layer by layer as the number of winding layers increases, with the tension of the last layer being 100N~150N. Controlling the winding tension in the wet winding process in this manner is more conducive to ensuring the stability of the finished yarn and further improving the problem of yarn delamination after curing.

[0063] In some embodiments, the curing process includes the following steps: placing the cylindrical winding body and the mandrel together in a curing oven, and heating and curing the cylindrical winding body while rotating. The curing process is as follows: curing at room temperature to 100°C for 190 min to 210 min, curing at 100°C for 490 min to 510 min, curing at 100°C to 150°C for 390 min to 410 min, curing at 150°C for 490 min to 510 min, curing at 150°C to 220°C for 180 min to 220 min, and curing at 220°C for 490 min to 510 min.

[0064] By employing the aforementioned heating and curing process with a relatively slow curing temperature rise rate, the risk of resin curing burst polymerization is reduced, thereby improving the stability of the product's performance. Resin curing burst polymerization refers to a violent and rapid polymerization reaction during the curing process caused by uncontrolled reaction, typically accompanied by the release of large amounts of heat, volume expansion, and potentially dangerous situations such as splashing and explosions.

[0065] In some embodiments, the initial carbonization treatment and chemical vapor deposition (CVD) densification treatment include the following steps: placing the resin-based composite preform in a CVD apparatus and processing it according to the following procedure: processing at room temperature to 200°C under nitrogen protection and constant pressure of 2.0 MPa to 3.0 MPa for 500 min to 530 min; processing at 200°C under nitrogen protection and constant pressure of 2.0 MPa to 3.0 MPa for 90 min to 120 min; and processing at 200°C to 600°C under nitrogen protection and constant pressure of 2.0 MPa to 3.0 MPa for 200 min to 240 min. Treatment can be carried out at 600℃ under constant temperature and nitrogen protection at a constant pressure of 2.0MPa~3.0MPa for 300min~360min; at 600℃~800℃ under vacuum to within 50Pa for 240min~300min; at 800℃~1300℃ under continuous introduction of carbon source gas and nitrogen, and furnace pressure of 5000Pa~8000Pa for 200min~280min; and at 1300℃ under constant temperature, continuous introduction of carbon source gas and nitrogen, and furnace pressure of 5000Pa~8000Pa for 6000min~10000min.

[0066] By adopting the above-mentioned initial carbonization treatment and chemical vapor deposition densification process, it is beneficial to introduce pyrolytic carbon source in a timely manner after the initial carbonization, effectively filling the voids and delamination caused by the volatilization of non-carbon substances in the cured part, which helps to further ensure the density and low damage rate of the product, thereby improving the product strength and service life.

[0067] In some embodiments, the impregnation carbonization densification treatment includes the following steps: placing the carbon-carbon composite material blank in an impregnation furnace, filling it with phenolic resin under vacuum, and letting it stand for 4 to 5 hours; filling it with nitrogen to a pressure of 4 MPa to 5 MPa, and holding the pressure for 8 to 10 hours to complete the impregnation; draining the resin liquid from the impregnation furnace and evacuating it to 50 kPa to 80 kPa; treating it at room temperature to 80°C and furnace pressure of 50 kPa to 80 kPa for 95 to 105 minutes; isothermal treatment at 80°C and furnace pressure of 50 kPa to 80 kPa for 55 to 65 minutes; treatment at 80°C to 180°C and furnace pressure of 50 kPa to 80 kPa for 195 to 205 minutes; and isothermal treatment at 180°C and furnace pressure of 100 kPa to 200 kPa for 495 to 505 minutes.

[0068] The above-described impregnation and carbonization densification process facilitates the full impregnation and filling of resin in carbon-carbon composite preforms, enabling effective carbonization and densification treatment of the preforms and improving the strength and service life of the products.

[0069] One embodiment of this application provides a carbon-carbon composite material cylinder, which is prepared by the carbon-carbon composite material cylinder preparation method described above. The carbon-carbon composite material cylinder of this application has high strength and a long service life, and can meet the performance requirements of carbon-carbon hot pressing molds in the field of special ceramic hot pressing sintering.

[0070] In some embodiments, the wall thickness of the carbon-carbon composite cylinder is 100mm to 200mm. The carbon-carbon composite cylinder of this application, with a wall thickness of 100mm to 200mm, does not exhibit cracking or delamination, possesses sufficient strength, and is a thick-walled, high-strength carbon-carbon composite cylinder that can well meet the performance requirements of carbon-carbon hot-pressing molds in the field of special ceramic hot-pressing sintering.

[0071] One embodiment of this application provides an application of the carbon-carbon composite material cylinder described above in the hot pressing sintering of special ceramics. Specifically, the carbon-carbon composite material cylinder is used as a hot pressing mold in the hot pressing sintering of special ceramics. The special ceramics include alumina ceramics, silicon nitride ceramics, silicon carbide ceramics, zirconium oxide ceramics, etc.

[0072] The present application will be further described below with reference to specific embodiments and comparative examples, but should not be construed as limiting the scope of protection of the present application.

[0073] Example 1:

[0074] (1) Mix and dissolve 1.5 parts by weight of anhydrous ethanol, 1.5 parts by weight of thermosetting boron-modified phenolic resin and 0.0015 parts by weight of γ-aminopropyltriethoxysilane to obtain an impregnation solution.

[0075] (2) Using 12K, T700 grade or higher polyacrylonitrile-based carbon fiber filaments as raw materials, the carbon fiber filaments are immersed in the above-mentioned impregnation solution, the carbon fiber filaments are taken out and the excess solution is squeezed off to obtain a glued carbon fiber with a solution volume content of 18%.

[0076] (3) The above-mentioned adhesive-coated carbon fiber is made into a cylindrical wound body by a wet winding process. The wet winding process is as follows:

[0077] A cylindrical metal mandrel with a detachable end cap is installed at the winding station, and a release agent is evenly applied to the surface of the mandrel. Adhesive-coated carbon fiber is wound onto the mandrel using an automated winding machine. The first layer of winding is completed using a longitudinal planar winding method, followed by a circumferential planar winding method for the second layer, and then a helical winding method for the third layer. A winding cycle is then completed with one longitudinal planar winding + one circumferential planar winding + one helical winding, and this cycle is repeated 120 times. Then, a winding cycle is completed with one longitudinal planar winding + nine circumferential planar windings, and this cycle is repeated 180 times. Finally, a winding cycle is completed with one longitudinal planar winding + one circumferential planar winding + one helical winding, and this cycle is repeated 120 times. During the wet winding process described above, the tension of the first layer is 1300N, and the tension of each subsequent layer decreases progressively, with the tension of the final layer being 120N.

[0078] (4) The tubular winding body obtained after wet winding is cured to obtain a resin-based composite material blank. The curing process is as follows: the tubular winding body and the mandrel are placed horizontally in a curing oven, and the tubular winding body is heated and cured while rotating. The curing temperature curve is as follows: first, it is cured at room temperature to 100℃ for 200 min, then at 100℃ for 500 min, then at 100℃ to 150℃ for 400 min, then at 150℃ for 500 min, then at 150℃ to 220℃ for 400 min, and finally at 220℃ for 500 min. After curing, it is taken out after cooling to room temperature, demolded, and the resin-based composite material blank is obtained.

[0079] (5) The resin-based composite material blank is placed in a chemical vapor deposition equipment for initial carbonization and chemical vapor deposition densification to obtain carbon-carbon composite material blank. The initial carbonization treatment and chemical vapor deposition (CVD) densification treatment steps are as follows: The resin-based composite material preform is placed in a CVD apparatus and treated according to the following process: First, it is treated for 500 min at room temperature to 200℃ under nitrogen protection and constant pressure of 2.0 MPa; then, it is treated for 100 min at 200℃ under nitrogen protection and constant pressure of 2.0 MPa; then, it is treated for 200 min at 600℃ under nitrogen protection and constant pressure of 2.0 MPa; then, it is treated for 300 min at 600℃ under nitrogen protection and constant pressure of 2.0 MPa; then, it is treated for 400 min at 800℃ under vacuum to within 100 Pa; then, it is treated for 200 min at 1000℃ with continuous introduction of carbon source gas and nitrogen and furnace pressure of 5000 Pa; and finally, it is treated for 8000 min at 1000℃ with continuous introduction of carbon source gas and nitrogen and furnace pressure of 5000 Pa.

[0080] (6) The carbon-carbon composite material blank is subjected to machining, impregnation carbonization densification treatment and graphitization treatment in sequence to obtain carbon-carbon composite material semi-finished product. The machining treatment steps are as follows: the carbon-carbon composite material blank is clamped on a lathe, and the end face is machined after the blank is aligned according to the machining drawings. Then, the inner diameter, outer diameter, height and other dimensions of the carbon-carbon composite material blank are machined to the dimensions required by the drawings in sequence. The steps of the impregnation carbonization densification treatment are as follows: The machined carbon-carbon composite material blank is placed in an impregnation furnace, filled with phenolic resin under vacuum, and left to stand for 5 hours; nitrogen is then introduced to a pressure of 5 MPa, and the pressure is maintained for 8 hours to complete the impregnation; the resin liquid in the impregnation furnace is discharged, and the vacuum is evacuated to 80 kPa; the furnace is treated at room temperature to 80°C and furnace pressure of 80 kPa for 100 minutes; the furnace is then treated at 80°C and furnace pressure of 80 kPa for 60 minutes; the furnace is then treated at 150°C and furnace pressure of 80 kPa for 200 minutes; and finally, the furnace is treated at 180°C and furnace pressure of 150 kPa for 500 minutes to complete the impregnation curing. The cured carbon-carbon composite material blank is then placed in a carbonization furnace, evacuated to below 1000 Pa, filled with nitrogen to atmospheric pressure, and the exhaust valve is opened at a pressure of 0.5 m... 3 Nitrogen gas is slowly and continuously introduced at a rate of / h; the temperature is increased to 900℃ at a rate of 100℃ / h, and held at 900℃ for 10h to complete the carbonization process. The graphitization process is as follows: the carbon-carbon composite material blank that has undergone carbonization is placed in a graphitization furnace, the vacuum is evacuated to below 1000Pa, and the vacuum pump is kept running continuously; the temperature is increased to 1500℃ at a rate of 30℃ / min, and held at 1500℃ for 180min; then the temperature is increased to 2300℃ at a rate of 10℃ / min, and held for 10h; the temperature is then cooled to room temperature to complete the graphitization process.

[0081] (7) After machining and surface polishing, a surface pyrolytic carbon layer is prepared to obtain a carbon-carbon composite cylinder. The wall thickness of the carbon-carbon composite cylinder is 150mm. The machining steps are as follows: the carbon-carbon composite semi-finished product is clamped on a lathe, and each part of the carbon-carbon composite semi-finished product is machined to the state required by the drawing according to the customer's finished product drawing. The surface polishing steps are as follows: after the machined product is placed securely, the parts with burrs or other abnormalities on the surface are simply polished with 900-grit sandpaper until there are no obvious burrs. Then, the dust removal and cleaning equipment is used to remove the floating dust from the product surface, and the product surface can be covered with tape. The steps for preparing the surface pyrolytic carbon layer are as follows: The carbon-carbon composite workpiece, after grinding and cleaning, is placed in the reaction chamber of a high-temperature chemical vapor deposition furnace, ensuring sufficient gaps between the workpieces to guarantee uniform flow of the reaction gas to all surfaces. After closing the furnace door, the vacuum system is activated to evacuate the reaction chamber to below 50 Pa, and pressure testing is performed to ensure good airtightness. Nitrogen gas is introduced until the furnace pressure reaches 3500 Pa, heating is started, and the furnace temperature is raised to 1100 °C at a heating rate of 8 °C / min before holding at that temperature. Simultaneously with the start of the holding period, propylene gas and nitrogen gas are mixed at a volume ratio of 1:8 and introduced into the reaction chamber. The furnace pressure is controlled at 6500 Pa by adjusting the gas flow rate for deposition. After 3900 min of deposition, the propylene gas is first shut off, while nitrogen gas is continued to be introduced, maintaining the furnace pressure below 8000 Pa. After 45 min, heating is turned off, and the furnace is slowly cooled to room temperature at a cooling rate of 6 °C / min. All gas lines and power are then shut off, and air is introduced into the furnace to atmospheric pressure. Finally, the furnace is opened and the workpiece is removed.

[0082] Examples 2-3:

[0083] Examples 2 and 3 are basically the same as Example 1, except that the volume content of the adhesive liquid on the carbon fiber in step (2) is 15% and 20%, respectively.

[0084] Comparative Example 1:

[0085] Comparative Example 1 is basically the same as Example 1, except that the volume content of the adhesive liquid for the carbon fiber in step (2) is 35%.

[0086] Comparative Example 2:

[0087] Comparative Example 2 uses a three-dimensional braiding molding process to prepare a carbon-carbon composite cylinder. The main steps are as follows:

[0088] (1) Preparation of three-dimensional braided preform: Using a large three-dimensional braiding machine, carbon fiber filaments are automatically braided according to the design program to obtain a porous carbon fiber preform with a three-dimensional braided structure.

[0089] (2) Chemical vapor deposition densification: The porous carbon fiber preform prepared in step (1) is placed in a CVD furnace, and natural gas is introduced under high temperature conditions of 1050°C and 2000Pa to complete the pyrolytic carbon densification and obtain the pyrolytic carbon carbon composite material preform.

[0090] The subsequent steps are the same as steps (6) to (7) in Example 1.

[0091] Comparative Example 3:

[0092] Comparative Example 3 uses a conventional winding process to prepare a carbon-carbon composite cylinder. The main steps are as follows:

[0093] Preparation of filament-wound preforms: Using filament-wound equipment, carbon fiber filaments are impregnated with adhesive (adhesive volume content is 18%) and then filament-wound according to the design procedure to obtain porous carbon fiber preforms with filament-wound structures.

[0094] The subsequent steps are the same as steps (6) to (7) in Example 1.

[0095] Testing method:

[0096] (1) Strength test of carbon-carbon composite cylinder

[0097] The carbon-carbon composite cylinder strength testing equipment is a "radial expansion tester," which mainly consists of a main frame that provides rigid support, a precisely controllable actuator, an expansion head that can expand radially and synchronously, a force sensor, a displacement sensor, a data acquisition system, and other components.

[0098] A carbon-carbon composite cylinder was cut into 30mm high annular samples, which were then fitted onto an expansion head in its contracted state. After the test was initiated, the actuator pushed the expansion head radially outward at a certain rate, applying uniform pressure to the inner wall of the sample to increase its circumference. The data acquisition system continuously and synchronously recorded the applied force and radial displacement during the test until the sample fractured or reached a predetermined displacement, at which point the test was terminated. The sample was disassembled, and the fracture morphology and failure mode were observed and recorded.

[0099] The maximum circumferential stress, i.e., the circumferential tensile strength, can be obtained by calculating the formula: circumferential stress = expansion force × coefficient / contact length between sample and expansion head / average wall thickness of sample.

[0100] (2) Evaluation of the service life of carbon-carbon composite cylinder as hot pressing mold

[0101] The manufactured product is put into normal use by the client until the average radial expansion of the inner diameter is ≥1%, or the total weight loss is ≥5%, or axial cracks appear, at which point it is considered to have failed. The service life is the time it takes for the carbon-carbon composite cylinder to fail.

[0102] The strength of the carbon-carbon composite cylinders of each embodiment and comparative example of this application was tested using the above method, and their service life as hot-pressing molds for special ceramic hot pressing was evaluated. The test results are shown in Table 1. In the table, " / " indicates that it did not exist or was not tested.

[0103] Table 1

[0104]

[0105] As shown in Table 1, the carbon-carbon composite material cylinders prepared by the methods in the various embodiments of this application exhibit high circumferential tensile strength and long service life. In Comparative Example 1, the excessively high volume content of the adhesive in the adhesive-backed fiber significantly reduced the circumferential tensile strength and service life of the prepared carbon-carbon composite material cylinder. In Comparative Examples 2 and 3, carbon-carbon composite material cylinders were prepared using a three-dimensional weaving process and a conventional winding method, respectively, resulting in lower circumferential tensile strength and service life.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a carbon-carbon composite material cylinder, characterized in that, Includes the following steps: Impregnating carbon fiber filaments with a wetting solution yields adhesive-coated carbon fibers with a volume content of 15% to 20%. The adhesive-coated carbon fiber is made into a cylindrical wound body by a wet winding process; in the wet winding process, the adhesive-coated carbon fiber is wound in a combination of longitudinal planar winding, circumferential planar winding and helical winding. The cylindrical winding body is cured to obtain a resin-based composite material blank. The resin-based composite material blank is placed in a chemical vapor deposition equipment and subjected to initial carbonization treatment and chemical vapor deposition densification treatment in the same furnace to obtain a carbon-carbon composite material blank. The carbon-carbon composite material blank is sequentially subjected to machining, impregnation carbonization densification treatment and graphitization treatment to obtain a carbon-carbon composite material semi-finished product; After mechanical processing and surface polishing, the carbon-carbon composite material semi-finished product is used to prepare a surface pyrolytic carbon layer to obtain the carbon-carbon composite material cylinder. The impregnation solution comprises the following components by mass: 1 to 2 parts anhydrous ethanol, 1 to 2 parts phenolic resin, and 0.001 to 0.002 parts silane coupling agent; The wet winding process includes the following steps: The adhesive-coated carbon fiber is wound onto the mandrel in a longitudinal planar winding manner to complete the first layer of winding, then wound in a circumferential planar winding manner to complete the second layer of winding, and then wound in a spiral winding manner to complete the third layer of winding. After completing the third layer of winding, the adhesive carbon fiber is wound 100 to 150 times in sequence, consisting of one layer of longitudinal planar winding, one layer of circumferential planar winding, and one layer of spiral winding. One layer of longitudinal planar winding and nine layers of circumferential planar winding are performed sequentially as one winding cycle, and the adhesive-coated carbon fiber is repeatedly wound for 150 to 200 cycles. The adhesive-coated carbon fiber is wound in sequence with one layer of longitudinal planar winding, one layer of circumferential planar winding, and one layer of spiral winding as one winding cycle, and the winding cycle is repeated 100 to 150 times.

2. The method for preparing the carbon-carbon composite material cylinder according to claim 1, characterized in that, In the wet winding process, the tension of the first winding layer is 1100N~1500N, and the winding tension decreases layer by layer as the number of winding layers increases, with the tension of the last winding layer being 100N~150N.

3. The method for preparing the carbon-carbon composite material cylinder according to any one of claims 1 to 2, characterized in that, The curing process includes the following steps: The cylindrical winding body and the mandrel are placed together in a curing oven, and the cylindrical winding body is heated and cured while rotating. The curing process is as follows: curing at room temperature to 100℃ for 190 min to 210 min, curing at 100℃ for 490 min to 510 min, curing at 100℃ to 150℃ for 390 min to 410 min, curing at 150℃ for 490 min to 510 min, curing at 150℃ to 220℃ for 180 min to 220 min, and curing at 220℃ for 490 min to 510 min.

4. The method for preparing the carbon-carbon composite material cylinder according to any one of claims 1 to 2, characterized in that, The initial carbonization and chemical vapor deposition densification processes include the following steps: The resin-based composite material preform was placed in a chemical vapor deposition (CVD) apparatus and processed according to the following procedure: 500-530 min at room temperature to 200°C under nitrogen protection and constant pressure of 2.0 MPa-3.0 MPa; 90-120 min at 200°C under nitrogen protection and constant pressure of 2.0 MPa-3.0 MPa; 200-240 min at 200°C to 600°C under nitrogen protection and constant pressure of 2.0 MPa-3.0 MPa; and 200-240 min at 600°C under nitrogen protection and constant pressure of 2.0 MPa-3.0 MPa. Treatment was carried out at a pressure of 2.0 MPa to 3.0 MPa for 300 to 360 minutes; at 600℃ to 800℃ with a vacuum of less than 50 Pa for 240 to 300 minutes; at 800℃ to 1300℃ with continuous introduction of carbon source gas and nitrogen and a furnace pressure of 5000 Pa to 8000 Pa for 200 to 280 minutes; and at a constant temperature of 1300℃ with continuous introduction of carbon source gas and nitrogen and a furnace pressure of 5000 Pa to 8000 Pa for 6000 to 10000 minutes.

5. The method for preparing the carbon-carbon composite material cylinder according to any one of claims 1 to 2, characterized in that, The impregnation carbonization densification treatment includes the following steps: The carbon-carbon composite material blank is placed in an impregnation furnace, and phenolic resin is filled in under vacuum. It is then left to stand for 4 to 5 hours. Nitrogen gas is then introduced to a pressure of 4 MPa to 5 MPa, and the pressure is maintained for 8 to 10 hours to complete the impregnation. Drain the resin liquid from the impregnation furnace and evacuate to 50 kPa~80 kPa; treat at room temperature to 80℃ and furnace pressure of 50 kPa~80 kPa for 95 min~105 min; maintain a constant temperature of 80℃ and furnace pressure of 50 kPa~80 kPa for 55 min~65 min; treat at 80℃~180℃ and furnace pressure of 50 kPa~80 kPa for 195 min~205 min; maintain a constant temperature of 180℃ and furnace pressure of 100 kPa~200 kPa for 495 min~505 min.

6. A carbon-carbon composite material cylinder, characterized in that, The carbon-carbon composite material cylinder is prepared by any one of the preparation methods of claims 1 to 5.

7. The carbon-carbon composite material cylinder according to claim 6, characterized in that, The wall thickness of the carbon-carbon composite material cylinder is 100mm~200mm.

8. The application of a carbon-carbon composite material cylinder as described in claim 6 or 7 in the hot pressing sintering of special ceramics.

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