A winding and impregnating forming method of an ultra-thin carbon carbon screen blank

Abstract

This invention discloses a method for winding and impregnating an ultrathin carbon-carbon screen preform, characterized by comprising: selecting reinforcing fiber materials and matrix materials; determining the winding regime; based on the selected reinforcing fiber materials and matrix materials, using a winding fixture and a wet fiber winding process to prepare a composite material body; subjecting the composite material body to a first high-temperature treatment to obtain a porous preform; impregnating the porous preform with asphalt; and after asphalt impregnation, performing a second high-temperature treatment to obtain the ultrathin carbon-carbon screen preform. The method of this invention, through two high-temperature treatment processes and an asphalt impregnation process, produces a preform with a low closed-pore ratio, which is beneficial for subsequent CVD deposition and carbonization processes and ultimately yields an ultrathin carbon-carbon screen with acceptable density.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, and in particular relates to a method for winding and impregnating ultrathin carbon screen blanks. Background Technology

[0002] The working principle of an electric propulsion ion engine is to first ionize the propellant using electrical energy. The ionized ions are then accelerated and extracted as they pass through a grid assembly with an ultra-thin screen structure, thereby generating long-term stable thrust. The grid assembly is the core component of the electric propulsion ion engine, and its design and manufacturing level directly determines the performance and lifespan of the propulsion system.

[0003] Conventional molybdenum metal gates have a lifespan of only 14,000 hours, far short of the 40,000-hour lifespan requirement for deep space exploration. To improve the structural performance of ultra-thin screen-structure gate assemblies, further research into the application of advanced materials is essential. Carbon-carbon composite materials possess advantages such as lightweight, high strength, low expansion, high temperature resistance, and resistance to ion sputtering, and are widely used in high-end equipment fields such as aviation and aerospace, making them an ideal alternative to molybdenum metal gates for electric propulsion ion engines. Furthermore, to ensure sufficient thrust for deep space exploration spacecraft, research into the design and manufacturing processes of large-diameter ultra-thin carbon-carbon screen gates (over 300 mm) is necessary.

[0004] The process of preparing ultrathin carbon-carbon screen gates can be roughly divided into three major steps: preform forming, CVD deposition and carbonization, and finishing. Among them, preform forming is the first and most critical process, which generally includes two processes: wet fiber winding and pressure curing. The quality of the preform also determines the difficulty of subsequent processes and the forming effect of the final product.

[0005] If a resin with a high carbon content is used directly as the wet winding matrix material during the preform forming process, the preform prepared can easily obtain a high residual carbon rate that meets the technical specifications in subsequent processes. However, there is also the problem of a high closed-cell rate, which makes it difficult for some closed pores to be densely carbonized by CVD during the carbonization process. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a winding and impregnation molding method for ultra-thin carbon-carbon screen blanks. Epoxy resin or polyvinyl alcohol is selected as the matrix material for wet winding of fibers in the blank forming process. After curing, a first high-temperature treatment is performed to remove most of the non-carbon elements in the matrix material, so that the reinforcing fibers have porous characteristics while maintaining adhesion and not falling apart. Then, the pores of the preform are filled by asphalt impregnation, and finally, an ultra-thin carbon-carbon screen blank is obtained by a second high-temperature treatment.

[0007] To address the aforementioned technical problems, this invention discloses a method for winding and impregnating an ultrathin carbon-carbon screen blank, comprising:

[0008] Select reinforcing fiber materials and matrix materials;

[0009] Determine the winding system;

[0010] Based on the selected reinforcing fiber material and matrix material, a composite material body is prepared by using a fiber wet winding process and curing through a winding fixture;

[0011] The composite material body undergoes a first high-temperature treatment to obtain a porous preform.

[0012] The porous precast structure was impregnated with asphalt.

[0013] After the asphalt impregnation is completed, a second high-temperature treatment is carried out to obtain an ultra-thin carbon screen blank.

[0014] In the above-mentioned winding and impregnation molding method for ultrathin carbon-carbon screen blanks, the reinforcing fiber material is selected according to the following principles:

[0015] Based on the thickness h, porosity w, outer diameter d, and maximum allowable weight m of the ultrathin carbon-carbon screen blank to be prepared, the minimum multifilament strength σ is calculated as follows:

[0016]

[0017] Where k1 represents the empirical strength parameter, and g represents the standard gravitational acceleration;

[0018] Materials with an average multifilament strength test value greater than σ were selected as reinforcing fiber materials.

[0019] In the above-mentioned winding and impregnation molding method for ultra-thin carbon screen blanks, the matrix material is selected according to the following principle: a material that can ensure that the reinforcing fibers remain bonded and do not fall apart after the first high-temperature treatment and has porous characteristics is selected as the matrix material.

[0020] In the above-mentioned method for winding and impregnating ultrathin carbon-carbon screen blanks, the winding regime is determined, including: determining the number of winding layers n of reinforcing fibers, the winding sequence and the winding belt distance b.

[0021] In the above-mentioned method for winding and impregnating ultrathin carbon screen blanks, the winding distance b is determined by the following formula:

[0022]

[0023] Where k2 represents the winding empirical parameter, l represents the unfolding bandwidth of the reinforcing fiber material during the winding process, and t represents the linear density value of the reinforcing fiber material.

[0024] In the above-mentioned winding and impregnation forming method for ultra-thin carbon screen blanks, the winding fixture includes: metal frame a, metal frame b, and graphite core mold.

[0025] Metal frame a and metal frame b overlap to form a regular hexagonal metal frame; where...

[0026] Metal frame a and metal frame b are both machined with overlapping steps at two overlapping positions, and are provided with screw holes a and b for connecting and fixing metal frame a and metal frame b.

[0027] The graphite core mold is located within a regular hexagonal metal frame;

[0028] Each side of the regular hexagonal metal frame is provided with a cutting groove;

[0029] The six corners of the regular hexagonal metal frame are sequentially machined with tightening holes a, b, c, fixing screw holes a, b, and c.

[0030] In the above-mentioned winding and impregnation molding method for ultrathin carbon-carbon screen blanks, the composite material body undergoes a first high-temperature treatment to obtain a porous preform, including:

[0031] Use metal tooling to wrap the composite material together with the tooling and clamp it in the middle, and fix it with screws;

[0032] The assembled composite material body, along with the winding fixture and metal fixture, is placed in an oven and cured according to the curing process parameters of the selected matrix material; the surface of the metal fixture in contact with the composite material body is flat, without obvious protrusions or pits.

[0033] After curing is complete, wait for natural cooling and then remove the composite material body along with the winding fixture and metal fixture from the oven. Remove the metal fixture and replace it with graphite plate fixture a. Clamp the composite material body along with the winding fixture in the middle and fix it with screws. Graphite plate fixture a includes two flat graphite plates a.

[0034] The assembled composite material body, along with the winding fixture and graphite plate fixture a, is placed into a high-temperature box furnace. The temperature of the high-temperature box furnace is gradually increased to a temperature range of 950℃±50℃ and maintained at a temperature range of 950℃±50℃ for no less than 6 hours for the first high-temperature treatment. During the first high-temperature treatment, the high-temperature box furnace is kept in an inert atmosphere.

[0035] After waiting for natural cooling, the composite material body, along with the winding fixture and graphite plate fixture a, is taken out of the high-temperature box furnace. The graphite plate fixture a is then removed to obtain the porous preform with the winding fixture.

[0036] In the above-mentioned method for winding and impregnating ultrathin carbon-carbon screen blanks, the porous preform is impregnated with asphalt, including:

[0037] Using graphite plate fixture b, the porous preform is wrapped and clamped in the middle and fixed with screws; wherein, graphite plate fixture b includes: two graphite plates b with one side surface flat and the other side surface processed with fine grid-like grooves; the side surface of graphite plate b with fine grid-like grooves is in contact with the porous preform.

[0038] The assembled porous precast body, along with the winding fixture and graphite plate fixture b, is placed into a container filled with solid asphalt. The container is then placed in an oven, and the oven temperature is adjusted to be higher than the melting temperature of the asphalt and kept at that temperature for at least 24 hours to allow the asphalt to fully impregnate the porous precast body.

[0039] In the above-mentioned method for winding and impregnating ultrathin carbon-carbon screen blanks, after the asphalt impregnation is completed, a second high-temperature treatment is performed to obtain the ultrathin carbon-carbon screen blank, including:

[0040] After waiting for natural cooling, the porous preform, along with the winding fixture and graphite plate fixture b, is taken out of the oven and then placed into a high-temperature box furnace.

[0041] The temperature of the high-temperature box furnace is gradually increased to a range of 950℃±50℃ and maintained at that range for no less than 12 hours for a second high-temperature treatment. During the second high-temperature treatment, the high-temperature box furnace is kept in an inert atmosphere.

[0042] After waiting for natural cooling, the porous preform, along with the winding fixture and graphite plate fixture b, is taken out of the high-temperature box furnace. The graphite plate fixture b and the winding fixture are then removed to obtain the ultra-thin carbon screen blank.

[0043] In the above-mentioned winding and impregnation forming method for ultra-thin carbon fiber screen blanks

[0044] The first high-temperature treatment is used to remove non-carbon elements from the matrix material and to maintain the adhesion of the reinforcing fibers within the specified high-temperature treatment range and time.

[0045] Asphalt impregnation is a specified asphalt impregnation process used to increase the density of porous precast structures.

[0046] The second high-temperature treatment is used to remove non-carbon elements from the impregnated asphalt and maintain the high-temperature treatment range and time specified for the ultra-thin carbon screen blank.

[0047] The present invention has the following advantages:

[0048] This invention discloses a winding and impregnation molding method for ultrathin carbon-carbon screen blanks. Through two high-temperature treatment processes and an asphalt impregnation process, the prepared blank has a low closed-cell ratio, which is beneficial for subsequent CVD deposition and carbonization processes and ultimately yields ultrathin carbon-carbon screens with qualified density. The ultrathin carbon-carbon screen blanks designed and manufactured using the method described in this invention can meet the index requirements of subsequent ultrathin carbon-carbon screen manufacturing processes. Attached Figure Description

[0049] Figure 1 This is a front view of a winding fixture according to an embodiment of the present invention;

[0050] Figure 2 This is a left view of a winding fixture according to an embodiment of the present invention;

[0051] Figure 3 yes Figure 2 AA view. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0053] In this embodiment, the winding and impregnation forming method for the ultrathin carbon-carbon screen blank includes:

[0054] Step 1: Select the reinforcing fiber material and the matrix material.

[0055] In this embodiment, the reinforcing fiber material can be selected according to the following principles:

[0056] Based on the thickness h, porosity w (i.e., the ratio of open area to open region area), outer diameter d, and maximum allowable weight m of the ultrathin carbon-carbon screen blank to be prepared, the minimum multifilament strength σ is calculated as follows:

[0057]

[0058] Where k1 represents the empirical parameter of fiber strength, which is generally taken as 5 to 8; g represents the standard gravitational acceleration.

[0059] Materials with an average multifilament strength test value greater than σ are selected as reinforcing fiber materials. To obtain a preform with the highest possible carbon content, reinforcing fiber materials are generally preferred from the carbon fiber material series.

[0060] Furthermore, the matrix material can be selected according to the following principles:

[0061] Materials that ensure the reinforcing fibers remain bonded and do not fall apart after the first high-temperature treatment and possess porous characteristics are selected as the matrix material. Process verification has shown that using epoxy resins or polyvinyl alcohol as the matrix material for the wet winding process can guarantee that the reinforcing fibers remain bonded and do not fall apart after the first high-temperature treatment and possess porous characteristics. Of course, other materials that can ensure the reinforcing fibers remain bonded and do not fall apart after the first high-temperature treatment and possess porous characteristics can also be used as the matrix material for the wet winding process.

[0062] Step 2: Determine the winding system.

[0063] In this embodiment, determining the winding system mainly includes: determining the number of winding layers n, the winding sequence, and the winding distance b of the reinforcing fiber. Taking an ultra-thin carbon-carbon screen blank containing single-layer fiber winding angles of 0°, 60°, and 120° as an example. First, the number of winding layers is determined. Since the ultra-thin carbon-carbon screen blank is designed with three winding angles (0°, 60°, and 120°), and considering that the number of cycles is not less than 2, the number of winding layers is determined to be 6. Furthermore, regarding the design of the winding sequence for each winding layer, it is not recommended to wind layers in the same direction together; therefore, the winding sequence is set to 0°, 60°, 120°, 60°, 120°, 0°. Further, the winding distance b can be determined using the following formula: Where k2 represents the empirical parameter for fiber winding, which is generally taken as 0.75 to 0.95, l represents the unfolding bandwidth of the reinforcing fiber material during the winding process, and t represents the linear density value of the reinforcing fiber material.

[0064] Step 3: Based on the selected reinforcing fiber material and matrix material, the composite material is prepared by using a fiber wet winding process with a winding fixture and then curing.

[0065] In this embodiment, the wet fiber winding process requires the use of winding fixtures. Taking an ultrathin carbon fiber screen blank containing single-layer fiber winding angles of 0°, 60°, and 120° as an example, a winding fixture was designed as follows: Figures 1-3The hexagonal winding fixture shown mainly includes: a metal frame a3, a metal frame b9, and a graphite core mold 6. The metal frames a3 and b9 overlap to form a regular hexagonal metal frame; both metal frames a3 and b9 have overlapping steps at two overlapping points, and are provided with screw holes a4 and b8 for connecting and fixing the metal frames a3 and b9; the graphite core mold 6 is located inside the regular hexagonal metal frame. Each side of the regular hexagonal metal frame is provided with a cutting groove 1, which is used to cut the fiber winding layer from the side after the fiber is wet-wound; the six corners of the regular hexagonal metal frame are sequentially machined with tightening holes a10, b11, c12, fixing screw holes a13, b14 and c15. By switching different fixing screw holes and corresponding tightening holes of the winding fixture, the reinforcing fiber layers with different winding directions can be completed. Then, the curing is carried out according to the curing regime of the selected matrix material to obtain the molded composite material.

[0066] Step 4: Perform the first high-temperature treatment on the composite material to obtain a porous preform.

[0067] In this embodiment, the first high-temperature treatment process is as follows:

[0068] Use metal tooling to wrap the composite material around the tooling and clamp it in the middle, and then fix it with screws.

[0069] The assembled composite material body, along with the winding fixture and metal fixture, is placed in an oven and cured according to the curing process parameters of the selected matrix material. The surface of the metal fixture in contact with the composite material body is smooth, without obvious protrusions or pits.

[0070] After curing is complete, allow the composite material to cool naturally before removing it from the oven along with the winding fixture and the metal fixture. Remove the metal fixture and replace it with graphite plate fixture a. Clamp the composite material along with the winding fixture in the middle and secure it with screws. Graphite plate fixture a consists of two flat graphite plates a.

[0071] The assembled composite material body, along with the winding fixture and graphite plate fixture a, is placed into a high-temperature box furnace. The temperature of the high-temperature box furnace is gradually increased to a range of 950℃±50℃ and maintained at this range for at least 6 hours for the first high-temperature treatment. During the first high-temperature treatment, the high-temperature box furnace is kept in an inert atmosphere, and nitrogen can be selected as the inert gas.

[0072] After waiting for natural cooling, the composite material body, along with the winding fixture and graphite plate fixture a, is taken out of the high-temperature box furnace. The graphite plate fixture a is then removed to obtain the porous preform with the winding fixture.

[0073] Step 5: Impregnate the porous precast body with asphalt.

[0074] In this embodiment, the asphalt impregnation process is as follows:

[0075] Using graphite plate fixture b, the porous precast body is wrapped and clamped in the middle, and fixed with screws. Graphite plate fixture b comprises two graphite plates b, one side of which is flat and the other side has a grid-like fine groove. The side of graphite plate b with the grid-like fine groove is in contact with the porous precast body. The function of the grid-like fine groove is to facilitate the entry of asphalt at high temperatures, thereby fully impregnating the porous precast body.

[0076] The assembled porous precast body, along with the winding fixture and graphite plate fixture b, is placed into a container containing a sufficient amount of solid asphalt. The container is then placed in an oven, and the oven temperature is adjusted to be higher than the melting temperature of the asphalt and kept at that temperature for at least 24 hours to allow the asphalt to fully impregnate the porous precast body.

[0077] Step 6: After the asphalt impregnation is completed, a second high-temperature treatment is carried out to obtain an ultra-thin carbon screen blank.

[0078] In this embodiment, the second high-temperature treatment process is as follows:

[0079] After waiting for natural cooling, the porous preform, along with the winding fixture and graphite plate fixture b, is taken out of the oven and then placed into a high-temperature box furnace.

[0080] The temperature of the high-temperature box furnace is gradually increased to a range of 950℃±50℃ and maintained at that range for no less than 12 hours for a second high-temperature treatment. During the second high-temperature treatment, the high-temperature box furnace is kept in an inert atmosphere.

[0081] After waiting for natural cooling, the porous preform, along with the winding fixture and graphite plate fixture b, is taken out of the high-temperature box furnace. The graphite plate fixture b and the winding fixture are then removed to obtain the ultra-thin carbon screen blank.

[0082] In this embodiment, step 4, the first high-temperature treatment, is mainly used to remove non-carbon elements from the matrix material and maintain the bonding of the reinforcing fibers within the specified high-temperature range and time. Step 5, asphalt impregnation, is mainly used to increase the density of the porous precast body within the specified asphalt impregnation process. Step 6, the second high-temperature treatment, is mainly used to remove non-carbon elements from the impregnated asphalt and maintain the ultra-thin carbon screen precast body within the specified high-temperature range and time.

[0083] Based on the above embodiments, the following is an explanation with reference to a specific example.

[0084] The minimum multifilament strength was calculated based on the empirical formula for minimum multifilament strength. A certain grade of domestically produced T800 carbon fiber was selected as the reinforcing fiber material. The matrix material was polyvinyl alcohol. The designed ultra-thin carbon-carbon screen blank had 6 winding layers and a thickness of 0.75 mm. Based on the winding angles of different winding layers, the designed winding sequence was 0°, 60°, 120°, 60°, 120°, 0°. The winding tape distance was calculated to be 0.65 mm based on the empirical formula for winding tape distance. According to the relevant process parameters of the selected matrix material, the determined curing regime was: room temperature → 80℃ / 1.5h → 100℃ / 12h → 135℃ / 6h → natural cooling in the furnace. After curing, the composite material and tooling were removed, and two specially made graphite plates with flat surfaces were used to heat the composite material. The material, along with the winding fixture, is clamped in the middle and fixed with screws before being placed in a high-temperature box furnace for the first high-temperature treatment, according to the following procedure: room temperature → 950℃ / 8h → natural cooling with the furnace. During the high-temperature treatment, the high-temperature box furnace is in a nitrogen atmosphere. The first high-temperature treatment produces a porous preform. A special graphite plate with one side flat and the other side processed with a grid-like fine groove is used to clamp the porous preform along with the winding fixture in the middle and fix it with screws. It is then placed in an oven and kept at 200℃ for 24h to allow the asphalt to fully impregnate the porous preform. After the asphalt impregnation is completed, the porous preform along with the graphite fixture is taken out and transferred to the high-temperature box furnace for the second high-temperature treatment, according to the following procedure: room temperature → 950℃ / 12h → natural cooling with the furnace. During the high-temperature treatment, the high-temperature box furnace is in a nitrogen atmosphere. Using this process, a total of 6 ultrathin carbon screen blanks were prepared. After subsequent CVD deposition carbonization and finishing processes, the ultrathin carbon screens obtained all passed the thermal environment test and mechanical property test.

[0085] In summary, this invention discloses a winding and impregnation molding method for ultrathin carbon-carbon screen blanks, which can be used to prepare ultrathin carbon-carbon screen blanks that meet the requirements of mechanical properties and density.

[0086] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0087] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for winding and impregnating an ultrathin carbon fiber screen blank, characterized in that, include: Select reinforcing fiber materials and matrix materials; Determine the winding system; Based on the selected reinforcing fiber material and matrix material, a composite material body is prepared by using a fiber wet winding process and curing through a winding fixture; The composite material body undergoes a first high-temperature treatment to obtain a porous preform. The porous precast structure was impregnated with asphalt. After the asphalt impregnation is completed, a second high-temperature treatment is carried out to obtain an ultra-thin carbon screen blank; The reinforcing fiber material should be selected according to the following principles: Based on the thickness h, porosity w, outer diameter d, and maximum allowable weight m of the ultrathin carbon-carbon screen blank to be prepared, the minimum multifilament strength σ is calculated as follows: Where k1 represents the empirical strength parameter, and g represents the standard gravitational acceleration; Materials with an average multifilament strength test value greater than σ were selected as reinforcing fiber materials; The matrix material is selected according to the following principle: the material that can ensure that the reinforcing fibers remain bonded and do not fall apart after the first high-temperature treatment and has a porous feature is selected as the matrix material.

2. The method for winding and impregnating ultrathin carbon screen blanks according to claim 1, characterized in that, Determine the winding regime, including: determining the number of winding layers n of the reinforcing fiber, the winding sequence, and the winding tape spacing b.

3. The method for winding and impregnating ultrathin carbon screen blanks according to claim 2, characterized in that, The winding distance b is determined by the following formula: Where k2 represents the winding empirical parameter, l represents the unfolding bandwidth of the reinforcing fiber material during the winding process, and t represents the linear density value of the reinforcing fiber material.

4. The method for winding and impregnating ultrathin carbon screen blanks according to claim 1, characterized in that, The winding fixture includes: a metal frame a (3), a metal frame b (9) and a graphite core mold (6); Metal frame a(3) and metal frame b(9) overlap to form a regular hexagonal metal frame; among which, Metal frame a(3) and metal frame b(9) are both machined with overlapping steps at two overlapping positions, and are provided with screw holes a(4) and screw holes b(8) for connecting and fixing metal frame a(3) and metal frame b(9); The graphite core mold (6) is located inside the regular hexagonal metal frame; Each side of the regular hexagonal metal frame is provided with a cutting groove (1); The six corners of the regular hexagonal metal frame are sequentially machined with a tightening hole a (10), a tightening hole b (11), a tightening hole c (12), a fixing screw hole a (13), a fixing screw hole b (14), and a fixing screw hole c (15).

5. The method for winding and impregnating ultrathin carbon screen blanks according to claim 1, characterized in that, The composite material undergoes a first high-temperature treatment to obtain a porous preform, comprising: Use metal tooling to wrap the composite material together with the tooling and clamp it in the middle, and fix it with screws; The assembled composite material body, along with the winding fixture and metal fixture, is placed in an oven and cured according to the curing process parameters of the selected matrix material; the surface of the metal fixture in contact with the composite material body is flat, without obvious protrusions or pits. After curing is complete, wait for natural cooling and then remove the composite material body along with the winding fixture and metal fixture from the oven. Remove the metal fixture and replace it with graphite plate fixture a. Clamp the composite material body along with the winding fixture in the middle and fix it with screws. Graphite plate fixture a includes two flat graphite plates a. The assembled composite material body, along with the winding fixture and graphite plate fixture a, is placed into a high-temperature box furnace. The temperature of the high-temperature box furnace is gradually increased to a temperature range of 950℃±50℃ and maintained at a temperature range of 950℃±50℃ for no less than 6 hours for the first high-temperature treatment. During the first high-temperature treatment, the high-temperature box furnace is kept in an inert atmosphere. After waiting for natural cooling, the composite material body, along with the winding fixture and graphite plate fixture a, is taken out of the high-temperature box furnace. The graphite plate fixture a is then removed to obtain the porous preform with the winding fixture.

6. The method for winding and impregnating ultrathin carbon screen blanks according to claim 5, characterized in that, The process of impregnating porous precast structures with bitumen includes: Using graphite plate fixture b, the porous preform is wrapped and clamped in the middle and fixed with screws; wherein, graphite plate fixture b includes: two graphite plates b with one side surface flat and the other side surface processed with fine grid-like grooves; the side surface of graphite plate b with fine grid-like grooves is in contact with the porous preform. The assembled porous precast body, along with the winding fixture and graphite plate fixture b, is placed into a container filled with solid asphalt. The container is then placed in an oven, and the oven temperature is adjusted to be higher than the melting temperature of the asphalt and kept at that temperature for at least 24 hours to allow the asphalt to fully impregnate the porous precast body.

7. The method for winding and impregnating ultrathin carbon screen blanks according to claim 6, characterized in that the asphalt... After impregnation, a second high-temperature treatment is performed to obtain an ultra-thin carbon-carbon screen blank, comprising: After waiting for natural cooling, the porous preform, along with the winding fixture and graphite plate fixture b, is taken out of the oven and then placed into a high-temperature box furnace. The temperature of the high-temperature box furnace is gradually increased to a range of 950℃±50℃ and maintained at that range for no less than 12 hours for a second high-temperature treatment. During the second high-temperature treatment, the high-temperature box furnace is kept in an inert atmosphere. After waiting for natural cooling, the porous preform, along with the winding fixture and graphite plate fixture b, is taken out of the high-temperature box furnace. The graphite plate fixture b and the winding fixture are then removed to obtain the ultra-thin carbon screen blank.

8. The method for winding and impregnating ultrathin carbon screen blanks according to claim 1, characterized in that, The first high-temperature treatment is used to remove non-carbon elements from the matrix material and to maintain the adhesion of the reinforcing fibers within the specified high-temperature treatment range and time. Asphalt impregnation is a specified asphalt impregnation process used to increase the density of porous precast structures. The second high-temperature treatment is used to remove non-carbon elements from the impregnated asphalt and maintain the high-temperature treatment range and time specified for the ultra-thin carbon screen blank.

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