Carbon / carbon composite material and its preparation method and PECVD supporting frame

Abstract

The present application relates to the technical field of carbon material, and provides a carbon / carbon composite material, a preparation method thereof and a PECVD bearing frame. The carbon / carbon composite material is prepared by sequentially performing layering and needling on a carbon fiber web, obtaining a needled preform, and then performing first impregnation, mold pressing, first carbonization, second impregnation, second carbonization and graphitization treatment. The PECVD bearing frame can be obtained by fine machining of the carbon / carbon composite material. The present application uses a web as raw material, and is relatively cheap, belonging to a low-cost preparation process. Compared with the conventional graphite bearing frame and the common carbon / carbon bearing frame in the field, the PECVD bearing frame provided by the present application has lower bulk density and better mechanical properties, can adapt to the complex process environment of PECVD, has low replacement frequency and long service period.

Description

Technical Field

[0001] This invention relates to the field of carbon materials technology, and in particular to a carbon / carbon composite material, its preparation method, and a PECVD support frame. Background Technology

[0002] Plasma-enhanced chemical vapor deposition (PECVD) is a novel technique that uses glow discharge plasma to induce a chemical reaction in gaseous substances containing thin film components, thereby achieving thin film material growth. The main advantages of PECVD are its low deposition temperature, minimal impact on the structure and physical properties of the substrate, good film thickness and compositional uniformity, dense film structure, and strong film adhesion. Currently, PECVD has a wide range of applications and can be used to prepare various metal films, inorganic films, and organic films.

[0003] PECVD boats are the carriers for silicon wafers during the coating process, and are generally made of graphite. However, graphite boats have low strength, and existing graphite carrier frames are mainly made by machining graphite sheets and adding corresponding accessories. This is limited by the structural design of the carrier frame itself and the material properties of graphite. The potential for increasing the silicon wafer loading capacity of graphite carrier frames is limited. Furthermore, in the harsh coating environment and pickling process, graphite carrier frames are easily damaged, significantly increasing the replacement frequency of graphite carrier frames and the cost of the PECVD process.

[0004] PECVD carbon / carbon carrier frames are carrier frames made of carbon / carbon composite materials, which have better mechanical properties and a longer service life than graphite boats. However, current carbon / carbon carrier frames usually use carbon cloth as the raw material, and carbon cloth itself is expensive, resulting in a high cost for carbon / carbon carrier frames; furthermore, the mechanical strength of current carbon / carbon carrier frames needs to be further improved. Summary of the Invention

[0005] In view of this, the present invention provides a carbon / carbon composite material, a method for preparing the same, and a PECVD support frame; the present invention uses a separate mesh as raw material to prepare the carbon / carbon composite material, which is inexpensive and low-cost, and the mechanical properties of the obtained PECVD support frame are superior to those of existing carbon / carbon support frames in the art.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for preparing a carbon / carbon composite material includes the following steps:

[0008] The carbon fiber mesh is sequentially laid up and needle-punched to obtain a needle-punched preform.

[0009] The needled preform is first impregnated in resin to obtain a prepreg.

[0010] The prepreg is laid up and then molded to obtain a slab;

[0011] The slab is subjected to a first carbonization process to obtain a carbonized slab.

[0012] The carbonized slab blank is second-impregnated in resin, followed by curing and second carbonization to obtain a carbon / carbon slab blank.

[0013] The carbon / carbon slab is graphitized to obtain the carbon / carbon composite material.

[0014] Preferably, the basis weight of the carbon fiber mesh is 100-200 g / m². 2 The number of carbon fiber mesh layers is 5 to 10; the needle punching density is 10 to 20 needles / cm. 2 ;

[0015] The first impregnation resin includes one or more of phenolic resin, furan resin, and benzoxazine resin;

[0016] The first impregnation includes: placing the needled preform in an impregnation tank, evacuating the impregnation tank, and when the vacuum degree is -0.09 to -0.1 MPa, connecting the impregnation tank to a resin tank, and drawing resin from the resin tank into the impregnation tank to impregnate the needled preform; the first impregnation time is 2 to 5 hours; the first impregnation time is calculated from the time the resin is drawn into the impregnation tank.

[0017] Preferably, the molding is performed in a molding fixture; the molding fixture is a metal frame structure.

[0018] Preferably, when the first impregnation resin is phenolic resin, the molding process includes eight stages, sequentially referred to as stage one to stage eight; the first stage is a heating stage, with a heating time of 40-50 minutes, a final temperature of 100-120°C, and a pressure of 0 MPa; the second stage is a heat preservation stage, with a heat preservation time of 40-50 minutes, a heat preservation temperature of 100-120°C, and a pressure of 0 MPa; the third stage is a heat preservation stage, with a heat preservation time of 3-5 minutes, a heat preservation temperature of 100-120°C, and a pressure of 0.3-0.35 MPa; the fourth stage is a heat preservation stage, with a heat preservation time of 3-5 minutes, a heat preservation temperature of 100-120°C, and a pressure of 0.5 MPa. The fifth stage is the heating stage, with a heating time of 50-60 minutes and a final temperature of 150-160°C. The pressure of the fifth stage is 0.5-0.6 MPa. The sixth stage is the heat preservation stage, with a heat preservation time of 30-40 minutes and a heat preservation temperature of 150-160°C. The pressure of the sixth stage is 0.5-0.6 MPa. The seventh stage is the heating stage, with a heating time of 50-70 minutes and a final temperature of 170-180°C. The pressure of the seventh stage is 0.5-0.6 MPa. The eighth stage is the heat preservation stage, with a heat preservation time of 70-80 minutes and a heat preservation temperature of 170-180°C. The pressure of the eighth stage is 0.5-0.6 MPa.

[0019] Preferably, the temperature of the first carbonization is 950-1100℃, the holding time is 1-3h, and the heating rate to the temperature of the first carbonization is 10-100℃ / h.

[0020] The resin used for the second impregnation includes one or more of phenolic resin, furan resin and benzoxazine resin; the temperature of the second impregnation is 80-100℃, the pressure is 2-4MPa, and the impregnation time is 2-4h; the curing temperature is 150-180℃.

[0021] Preferably, the second carbonization includes six stages performed sequentially, referred to as the first stage to the sixth stage; the first stage is a heating stage, starting from room temperature and heating to a final temperature of 200-220°C for 2-3 hours; the second stage is a holding stage, with a holding temperature of 200-220°C for 2-2.5 hours; the third stage is a heating stage, heating from the temperature of the second stage to 600-630°C for 15-25 hours; the fourth stage is a holding stage, with a holding temperature of 600-630°C for 1-2 hours; the fifth stage is a heating stage, heating from the temperature of the fourth stage to 800-850°C for 2-4 hours; and the sixth stage is a holding stage, with a holding temperature of 800-850°C for 2-2.5 hours.

[0022] Preferably, the graphitization treatment temperature is 1800–2300℃, and the holding time is 2–3 hours.

[0023] The present invention also provides a carbon / carbon composite material prepared by the preparation method described above.

[0024] The present invention also provides a PECVD support frame, which is prepared from the carbon / carbon composite material described in the above scheme.

[0025] The present invention also provides a method for preparing the PECVD support frame described in the above scheme, comprising the following steps: performing precision machining on the carbon / carbon composite material described in the above scheme to obtain the PECVD support frame.

[0026] This invention provides a method for preparing carbon / carbon composite materials, comprising the following steps: sequentially laying and needle-punching a carbon fiber mesh to obtain a needle-punched preform; first impregnating the needle-punched preform in resin to obtain a prepreg; laying the prepreg and then molding it to obtain a blank; first carbonizing the blank to obtain a carbonized blank; second impregnating the carbonized blank in resin, followed by sequential curing and second carbonization to obtain a carbon / carbon blank; and graphitizing the carbon / carbon blank to obtain the carbon / carbon composite material. This invention uses a carbon fiber mesh as raw material to prepare carbon / carbon composite materials without adding carbon cloth or other materials, making it relatively inexpensive compared to other molding processes, representing a low-cost preparation process. Furthermore, the carbon fiber mesh of this invention can be recycled from waste materials left over from the production of other products, which can be broken down and reused, turning waste into treasure and greatly reducing the operating costs of enterprises. Additionally, the needle-punching process of this invention can improve the mechanical properties of the resulting carbon / carbon composite material.

[0027] Furthermore, this invention prevents the mesh from cracking during the molding process by rationally designing the density and number of needle punches. At the same time, this invention designs a molding tooling that can effectively prevent the uneven flow of fibers during the molding process from causing the internal fiber warping of the board, thereby ensuring the performance of the obtained carbon / carbon composite material.

[0028] This invention also provides a PECVD support frame, processed from the carbon / carbon composite material described in the above-described scheme. Compared with traditional graphite support frames and ordinary carbon / carbon support frames in the art, the PECVD support frame provided by this invention has a lower bulk density and better mechanical properties. Compared with traditional graphite support frames, it also has the advantage of customizable dimensions. In summary, the PECVD support frame provided by this invention not only has low manufacturing cost but also excellent mechanical properties, can adapt to the complex process environment of PECVD, is not easily damaged, has a low replacement frequency, and a long service life, effectively reducing the cost of the PECVD process. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process for preparing carbon / carbon composite materials and PECVD tooling according to the present invention;

[0030] Figure 2 This is a schematic diagram of the molding tooling used in this invention;

[0031] Figure 3 This is a schematic diagram of the PECVD carrier frame of the present invention. Detailed Implementation

[0032] This invention provides a method for preparing carbon / carbon composite materials, comprising the following steps:

[0033] The carbon fiber mesh is sequentially laid up and needle-punched to obtain a needle-punched preform.

[0034] The needled preform is first impregnated in resin to obtain a prepreg.

[0035] The prepreg is laid up and then molded to obtain a slab;

[0036] The slab is subjected to a first carbonization process to obtain a carbonized slab.

[0037] The carbonized slab blank is second-impregnated in resin, followed by curing and second carbonization to obtain a carbon / carbon slab blank.

[0038] The carbon / carbon slab is graphitized to obtain the carbon / carbon composite material.

[0039] Figure 1 This is a schematic diagram of the process for preparing carbon / carbon composite materials and PECVD tooling according to the present invention. The following is a description of the process. Figure 1Provide a detailed explanation.

[0040] This invention involves sequentially laying and needle-punching a carbon fiber mesh to obtain a needle-punched preform. In this invention, the basis weight of the carbon fiber mesh is preferably 100–200 g / m². 2 More preferably 130-180 g / m 2 In this invention, the carbon fiber mesh is preferably prepared by breaking down waste mesh materials, such as waste generated during the preparation of pot trays, insulated containers, etc. Using waste materials as raw materials further reduces preparation costs. The number of carbon fiber mesh layers is preferably 5 to 10, more preferably 6 to 8. The needle-punching density is preferably 10 to 20 needles / cm. 2 More preferably, 15-18 stitches / cm 2 In this invention, it is preferable to cut the carbon fiber mesh before laying it in layers, and the cutting size can be determined according to actual needs. In a specific embodiment of this invention, it is preferable to first lay the carbon fiber mesh layer by layer on a flat plate, and then transfer it to a flat plate needle punching machine for needle punching, with multiple sets of needle punching according to the process sheet requirements, generally between 2 and 10 sets.

[0041] After obtaining the needled preform, the present invention performs a first impregnation of the needled preform in resin to obtain a prepreg. In the present invention, the resin used for the first impregnation preferably includes one or more of phenolic resin, furan resin, and benzoxazine resin; the phenolic resin preferably includes Y6412 from Guangming Resin Factory and / or PR55738 from Sumitomo Corporation of Japan; the furan resin is preferably HW154; the benzoxazine resin preferably includes Henkel Loctite BZ9110 or AERO; in the present invention, the first impregnation preferably includes: placing the needled preform in an impregnation tank, evacuating the impregnation tank until the vacuum degree is -0.09 to -0.1 MPa, connecting the impregnation tank to a resin tank, and drawing the resin from the resin tank into the impregnation tank to impregnate the needled preform; the first impregnation time is 2 to 5 hours; the first impregnation time is calculated from the time the resin is drawn into the impregnation tank. After the first impregnation is completed, the resin in the impregnation tank is preferably recovered.

[0042] After obtaining the prepreg, the present invention lays up the prepreg and then molds it to obtain a slab. In the present invention, the number of prepreg layers is preferably 4 to 8; the molding is preferably carried out in a molding fixture; the molding fixture is preferably a metal frame structure; in a specific embodiment of the present invention, the molding fixture is preferably a square frame composed of four metal strips, the square frame having an inner diameter of 560 mm, an outer diameter of 600 mm, and a thickness of 10 mm; Figure 2This is a schematic diagram of the molding fixture of the present invention. In a specific embodiment of the present invention, it is preferable to first place the prepreg in the molding fixture, and then mold the prepreg in a molding machine. The molding thickness can be adjusted according to the required dimensions of the final product, specifically by adjusting the layup thickness of the prepreg. The present invention, through the design of the molding fixture and the limiting of the fixture's perimeter, can ensure limited resin outflow, prevent carbon fiber flow due to excessive resin outflow, and avoid fiber warping within the sheet.

[0043] In this invention, the specific molding conditions are preferably set according to the characteristics of the resin. In this invention, when the first impregnation resin is phenolic resin, the molding includes eight stages, sequentially referred to as stage one to stage eight. The first stage is a heating stage, with a heating time of 40-50 minutes and a final temperature of 100-120°C, preferably 100°C, 110°C, or 120°C, and a pressure of 0 MPa. The second stage is a heat preservation stage, with a heat preservation time of 40-50 minutes and a heat preservation temperature of 100-120°C, preferably 100°C, 110°C, or 120°C, and a pressure of 0 MPa. The third stage is a heat preservation stage, with a heat preservation time of 3-5 minutes and a heat preservation temperature of 100-120°C, preferably 100°C, 110°C, or 120°C, and a pressure of 0.3-0.35 MPa. The fourth stage is the heat preservation stage, with a heat preservation time of 3-5 minutes, a heat preservation temperature of 100-110℃, and a pressure of 0.5-0.6 MPa; the fifth stage is the heating stage, with a heating time of 50-60 minutes, a heating endpoint temperature of 150-160℃, and a pressure of 0.5-0.6 MPa; the sixth stage is the heat preservation stage, with a heat preservation time of 30 minutes, a heat preservation temperature of 150-160℃, and a pressure of 0.5-0.6 MPa; the seventh stage is the heating stage, with a heating time of 50-70 minutes, a heating endpoint temperature of 170-180℃, and a pressure of 0.5-0.6 MPa; the eighth stage is the heat preservation stage, with a heat preservation time of 70-80 minutes, a heat preservation temperature of 170-180℃, and a pressure of 0.5-0.6 MPa.

[0044] After obtaining the slab, the present invention performs a first carbonization on the slab to obtain a carbonized slab. In the present invention, the first carbonization process needs to match the thermogravimetric curve of the resin. Specifically, the temperature of the first carbonization is preferably 950-1100℃, more preferably 1000-1050℃, the holding time is preferably 1-3h, more preferably 2h, and the heating rate to the first carbonization temperature is preferably 10-100℃ / h, more preferably 30-70℃ / h. After the first carbonization holding is completed, it is preferred to cool down, and the cooling rate is preferably 50-100℃ / h, with the final cooling temperature being room temperature. In the present invention, the carbonization is preferably carried out in a carbonization furnace. In order to reduce the deformation and delamination of the slab during the first carbonization process, it is preferred to place the slab between two graphite plate fixtures, and preferably 18-25 plates are placed between the two graphite fixtures.

[0045] After the first carbonization, the carbonized slab is subjected to a second impregnation in resin, followed by curing and a second carbonization to obtain a carbon / carbon slab. In this invention, the resin used for the second impregnation preferably includes one or more of phenolic resin, furan resin, and benzoxazine resin; the specific types of the phenolic resin, furan resin, and benzoxazine resin are the same as those used in the first impregnation, and will not be repeated here; the preferred temperature for the second impregnation is 80–100°C, the preferred pressure is 2–4 MPa, more preferably 2.5–3.5 MPa, and the preferred impregnation time is 2–4 h, more preferably 2–3 h; under the temperature conditions of the second impregnation, the viscosity of the resin is 2000–8000 mPa·s; the preferred curing temperature is 150–180°C, more preferably 160–180°C, and the preferred curing time is 3 h. In a specific embodiment of the present invention, it is preferable to place the carbonized slab blank in a vacuum impregnation furnace, raise the temperature of the vacuum impregnation furnace to 800-100°C, use the vacuum pressure difference to draw the resin into the vacuum pressure impregnation furnace, then pressurize it to 2-4 MPa, hold the pressure for 2-4 hours, and then return the excess resin liquid. After that, raise the temperature to 150-180°C to cure the resin impregnated in the carbonized slab. After curing, it is preferable to take out the slab and place it in a carbonization furnace for a second carbonization.

[0046] In this invention, the second carbonization is preferably matched with the thermogravimetric curve of the second impregnation resin; specifically, the second carbonization preferably includes six stages performed sequentially, referred to as the first stage to the sixth stage; the first stage is preferably a heating stage, starting from room temperature, with the final temperature of the heating preferably being 200-220°C, and the heating time preferably being 2-3 hours; the second stage is preferably a heat preservation stage, with the heat preservation temperature preferably being 200-220°C, and the heat preservation time preferably being 2-2.5 hours; the third stage is preferably a heating stage, starting from the temperature of the second stage... The temperature is raised to 600-630℃, and the heating time is preferably 15-25 hours, more preferably 15 hours, 20 hours or 25 hours; the fourth stage is preferably a heat preservation stage, the heat preservation temperature is preferably 600-630℃, and the heat preservation time is preferably 1-2 hours; the fifth stage is preferably a heating stage, raising the temperature from the fourth stage to 800-850℃, and the heating time is preferably 2-4 hours, more preferably 2 hours, 3 hours or 4 hours; the sixth stage is preferably a heat preservation stage, the heat preservation temperature is preferably 800-850℃, and the heat preservation time is preferably 2-2.5 hours.

[0047] In this invention, the second carbonization is preferably carried out in a carbonization furnace, and the furnace pressure is preferably slightly positive (approximately tens of Pascals); the second carbonization is preferably carried out under nitrogen protection. After the second carbonization is completed, the nitrogen valve is preferably closed and cooling begins. When the furnace temperature drops to 200°C, the lid is opened and the carbon / carbon slab is removed.

[0048] In this invention, the density of the carbon / carbon slab is preferably 1.5 g / cm³. 3 More preferably, it is 1.5–1.6 g / cm³. 3 If the density of the slab obtained after the second carbonization is less than 1.5 g / cm³ 3 In this case, it is preferable to repeat the second impregnation and second carbonization processes until the density of the resulting carbon / carbon slab is 1.5 g / cm³. 3 That's all. In a specific embodiment of the present invention, one cycle consists of one second impregnation and one second carbonization, and preferably 2 to 4 cycles are performed.

[0049] After obtaining the carbon / carbon slab, the present invention performs graphitization treatment on the carbon / carbon slab to obtain the carbon / carbon composite material. In the present invention, the graphitization treatment temperature is preferably 1800-2300℃, more preferably 1900-2100℃, and the holding time is preferably 2-3 hours; during the graphitization treatment, graphite tooling is preferably added to the carbon / carbon slab; the present invention improves the graphitization degree of the board and reduces the internal ash content through graphitization treatment.

[0050] The present invention also provides a carbon / carbon composite material prepared by the preparation method described above.

[0051] This invention also provides a PECVD support frame, prepared from the carbon / carbon composite material described in the above-described scheme. In this invention, the preferred dimensions of the PECVD support frame are 2500mm × 1500mm, and the preferred thickness is 1–20mm; the preferred density of the PECVD support frame is 1.5g / cm³. 3 More preferably, it is 1.5–1.6 g / cm³. 3 ; Figure 3 This is a schematic diagram of the PECVD carrier frame of the present invention.

[0052] The present invention also provides a method for preparing the PECVD support frame described in the above scheme, comprising the following steps: performing precision machining on the carbon / carbon composite material described in the above scheme to obtain the PECVD support frame; the precision machining steps include grinding, edge trimming and milling.

[0053] The carbon PECVD support frame provided by this invention has advantages over traditional graphite support frames, including lower density, higher strength, and customizable dimensions. Compared to ordinary carbon / carbon PECVD support frames in the art, it also boasts lower density and higher strength. When applied to plasma-enhanced chemical vapor deposition (PECVD), the PECVD support frame of this invention can adapt to complex process environments, requires less frequent replacement, and has a long service life. Table 1 compares the PECVD support frame of this invention with traditional graphite support frames and ordinary carbon / carbon PECVD support frames in the art.

[0054] Table 1. Performance Comparison Results of the PECVD Bearing Frame of the Present Invention, Traditional Graphite Bearing Frame, and Ordinary Carbon / Carbon Bearing Frame

[0055]

[0056]

[0057] Note: The ordinary carbon / carbon carrier frames in Table 1 are commercially available carbon carrier frames (Natek, Japan).

[0058] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. 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.

[0059] Example 1

[0060] Process 1: Laying the mesh

[0061] First, the carbon fiber mesh (weight 100g / m²) is... 2Cut the mesh to the required length according to the process specifications. Then lay the mesh layer by layer on the flat plate, with 6 layers forming a group.

[0062] Process 2: Mesh needle punching

[0063] The laid-up carbon fiber mesh was then transferred to a flatbed needle punching machine for needle punching at a density of 15 needles / cm. 2 According to the process sheet, multiple sets of needle punches are required, totaling 6 sets.

[0064] Step 3: Resin Impregnation

[0065] Multiple sets of mesh from step 2 are placed in a resin impregnation tank for resin impregnation. First, the impregnation tank is evacuated until the vacuum level reaches -0.09 to -0.1 MPa. Then, the resin tank is connected, and phenolic resin (Y6412) is drawn into the impregnation tank by vacuuming for impregnation. The impregnation time is 2 hours to obtain prepreg. Then, the resin in the impregnation tank is recycled.

[0066] Step 4: Molding

[0067] The six prepreg layers obtained after impregnation are laid up and transferred to a molding fixture for pressing. A schematic diagram of the molding fixture is shown below. Figure 2 As shown in Table 2. The molding thickness is selected as 6mm. The molding process conditions are shown in Table 2.

[0068] Table 2 Molding process conditions

[0069]

[0070]

[0071] Step 5: Carbonization

[0072] After molding, the slab is transferred to a carbonization furnace for carbonization. To reduce deformation and delamination during carbonization, the slab is placed between two graphite plate fixtures. The carbonization temperature is 900℃, the holding time is 2 hours, and the heating rate is 1℃ / min. After holding, the slab is cooled at a rate of 1.5℃ / min. The carbonized slab is then obtained.

[0073] Step 6: Liquid phase impregnation carbonization

[0074] The carbonized slab is impregnated with liquid phase. The carbonized slab is placed in a vacuum impregnation furnace and impregnated with phenolic resin (Y6412). The vacuum impregnation furnace needs to be heated to 80°C to reduce the viscosity of the resin. The impregnation liquid is completely drawn into the furnace containing the slab using the vacuum pressure difference. Then, the pressure is increased to 2MPa and held for 2 hours. The excess impregnation liquid is then returned. The furnace is heated to 150°C to harden the resin.

[0075] The sheet material was then removed and placed in a carbonization furnace for carbonization, as shown in Table 3. After carbonization, it underwent three more impregnation and carbonization cycles to obtain a material with a density of 1.55 g / cm³. 3 Carbon / carbon slab.

[0076] Table 3 Carbonization process conditions

[0077]

[0078] Step 7: High-temperature graphitization

[0079] Carbon / carbon slabs that meet the density requirements are subjected to high-temperature graphitization treatment using graphite fixtures at a temperature of 1800℃ for 2 hours to improve the graphitization degree of the slabs and reduce the internal ash content.

[0080] Step 8: Processing

[0081] The graphitized blank is precision machined according to the final structural design of the support frame. The main machining steps include grinding, trimming, and milling.

[0082] Example 2

[0083] Process 1: Laying the mesh

[0084] First, the carbon fiber mesh (weight 150g / m²) is... 2 Cut the material to the required length according to the process specifications. Then lay the material layer by layer on the flat plate, with 7 layers forming a group.

[0085] Process 2: Mesh needle punching

[0086] The laid mesh is then transferred to a flatbed needle punching machine for needle punching at a density of 20 needles / cm. 2 According to the process sheet, multiple sets of needle punches are required, totaling 7 sets.

[0087] Step 3: Resin Impregnation

[0088] Multiple sets of mesh from step 2 are placed in a resin impregnation tank for resin impregnation. First, the impregnation tank is evacuated until the vacuum level reaches -0.09 to -0.1 MPa. Then, the resin tank is connected, and phenolic resin is drawn into the impregnation tank through vacuuming for impregnation. The impregnation time is 3 hours, and then the resin in the impregnation tank is recovered.

[0089] Step 4: Molding

[0090] After impregnation, the seven sets of prepreg were laid up and transferred to a molding fixture for pressing. A schematic diagram of the molding fixture is shown below. Figure 2 As shown in Table 4, the molding process conditions are as follows, with a molding thickness of 8 mm selected.

[0091] Table 4 Molding process conditions

[0092]

[0093] Step 5: Carbonization

[0094] After molding, the slab is transferred to a carbonization furnace for carbonization. To reduce deformation and delamination during carbonization, the slab is placed between two graphite plate fixtures. The carbonization temperature is 950℃, the holding time is 3 hours, the heating rate is 1℃ / min, and after holding, the slab is cooled at a rate of 1.5℃ / min.

[0095] Step 6: Liquid phase impregnation carbonization

[0096] After carbonization, the sheet material undergoes liquid-phase impregnation. The sheet is placed in a vacuum pressure impregnation furnace and impregnated with resin. The furnace temperature is raised to 90°C to reduce resin viscosity. The impregnation liquid is drawn into the furnace containing the sheet using vacuum pressure difference. The pressure is then increased to 3 MPa and maintained for 3 hours. Excess impregnation liquid is then returned, and the furnace temperature is raised to 170°C to harden the resin. The sheet material is then removed and placed in a carbonization furnace for carbonization, as shown in Table 5. After carbonization, the impregnation and carbonization processes are repeated three times. The resulting carbon / carbon sheet has a density of 1.6 g / cm³. 3 .

[0097] Table 5 Carbonization process conditions

[0098]

[0099] Step 7: High-temperature graphitization

[0100] Carbon / carbon slabs that meet the density requirements are subjected to high-temperature graphitization treatment using graphite fixtures at a temperature of 1900℃ for 4 hours to improve the graphitization degree of the slabs and reduce the internal ash content.

[0101] Step 8: Processing

[0102] The graphitized blank is precision machined according to the final structural design of the support frame. The main machining steps include grinding, trimming, and milling.

[0103] The performance of the carrier frames prepared in Examples 1 and 2 was tested, and the results are shown in Table 6.

[0104] Table 6 Performance test results of the load-bearing frame in Examples 1-2

[0105]

[0106]

[0107] As can be seen from the data in Table 1, the PECVD carrier frame provided by this invention has low density and high strength, which can significantly improve its service life. At the same time, this invention uses mesh tires as raw materials, resulting in low preparation costs.

[0108] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon / carbon composite material, characterized in that, Includes the following steps: The carbon fiber mesh is sequentially laid up and needle-punched to obtain a needle-punched preform. The needled preform is first impregnated in resin to obtain a prepreg. The prepreg is laid up and then molded to obtain a slab; The slab is subjected to a first carbonization process to obtain a carbonized slab. The carbonized slab blank is second-impregnated in resin, followed by curing and second carbonization to obtain a carbon / carbon slab blank. The carbon / carbon blank is graphitized to obtain the carbon / carbon composite material; The carbon fiber mesh has a basis weight of 100~200g / m². 2 The number of carbon fiber mesh layers is 5 to 10; the needle punching density is 10 to 20 needles / cm. 2 The first impregnation resin is phenolic resin; the second impregnation resin is one or more of phenolic resin, furan resin and benzoxazine resin; the temperature of the second impregnation is 80~100℃, the pressure is 2~4MPa, and the impregnation time is 2~4h. The molding process comprises eight stages, denoted sequentially as Stage 1 to Stage 8. Stage 1 is the heating stage, with a heating time of 40-50 minutes, a final temperature of 100-120°C, and a pressure of 0 MPa. Stage 2 is the heat preservation stage, with a heat preservation time of 40-50 minutes, a heat preservation temperature of 100-120°C, and a pressure of 0 MPa. Stage 3 is the heat preservation stage, with a heat preservation time of 3-5 minutes, a heat preservation temperature of 100-120°C, and a pressure of 0.3-0.35 MPa. Stage 4 is the heat preservation stage, with a heat preservation time of 3-5 minutes, a heat preservation temperature of 100-120°C, and a pressure of 0.5-0.6 MPa. The fifth stage is the heating stage, with a heating time of 50-60 minutes and a final temperature of 150-160℃. The pressure in this stage is 0.5-0.6 MPa. The sixth stage is the heat preservation stage, with a heat preservation time of 30-40 minutes and a final temperature of 150-160℃. The pressure in this stage is 0.5-0.6 MPa. The seventh stage is the heating stage, with a heating time of 50-70 minutes and a final temperature of 170-180℃. The pressure in this stage is 0.5-0.6 MPa. The eighth stage is the heat preservation stage, with a heat preservation time of 70-80 minutes and a final temperature of 170-180℃. The pressure in this stage is 0.5-0.6 MPa. The second carbonization process comprises six sequential stages, referred to as Stage 1 to Stage 6. Stage 1 is a heating stage, starting from room temperature and increasing to a final temperature of 200-220°C over a period of 2-3 hours. Stage 2 is a holding stage, with a holding temperature of 200-220°C for 2-2.5 hours. Stage 3 is a heating stage, increasing the temperature from Stage 2 to 600-630°C over a period of 15-25 hours. Stage 4 is a holding stage, with a holding temperature of 600-630°C for 1-2 hours. Stage 5 is a heating stage, increasing the temperature from Stage 4 to 800-850°C over a period of 2-4 hours. Stage 6 is a holding stage, with a holding temperature of 800-850°C for 2-2.5 hours.

2. The preparation method according to claim 1, characterized in that, The first impregnation includes: placing the needled preform in an impregnation tank, evacuating the impregnation tank, and when the vacuum degree is -0.09 to -0.1 MPa, connecting the impregnation tank to a resin tank, and drawing resin from the resin tank into the impregnation tank to impregnate the needled preform; the first impregnation time is 2 to 5 hours; the first impregnation time is calculated from the time the resin is drawn into the impregnation tank.

3. The preparation method according to claim 1, characterized in that, The molding is performed in a molding fixture; the molding fixture is a metal frame structure.

4. The preparation method according to claim 1, characterized in that, The first carbonization temperature is 950~1100℃, the holding time is 1~3h, and the heating rate to the first carbonization temperature is 10~100℃ / h; the curing temperature is 150~180℃.

5. The preparation method according to claim 1, characterized in that, The graphitization treatment is carried out at a temperature of 1800~2300℃ and the holding time is 2~3h.

6. The carbon / carbon composite material prepared by the preparation method according to any one of claims 1 to 5.

7. A PECVD carrier frame, characterized in that, It is prepared from the carbon / carbon composite material described in claim 6.

8. The method for preparing the PECVD carrier frame according to claim 7, characterized in that, The process includes the following steps: precision machining of the carbon / carbon composite material as described in claim 6 to obtain the PECVD support frame.

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