Preparation method of high-performance carbon fiber 2.5D flat plate

Abstract

The application relates to the technical field of composite material preparation, and specifically discloses a preparation method of a high-performance carbon fiber 2.5D flat plate. The preparation method comprises the following steps: S1, preparing carbon cloth and a net tire; S2, preparing a preform: adopting the carbon cloth and the net tire to form unit layers, alternately laying the unit layers, and layer-by-layer needling, first using a first needle to perform needling, and when the thickness of the plate is greater than 6 mm, using a second needle to perform needling; compared with the first needle, the distance from the first stabbing point of the second needle to the needle tip is shortened by 1-2 mm, other hooks are adjusted to the position of the needle tip, the adjustment distance is equal to the distance from the first stabbing point of the second needle to the needle tip, and the needle hook angle of the second needle is smaller than that of the first needle by 5-6 DEG; and S3, obtaining a C / C flat plate through deposition, impregnation, carbonization, high-temperature treatment and machining treatment of the fiber preform obtained in the above step. The method can be used for preparing a carbon fiber flat plate, the carbon fiber flat plate prepared by the method has small pinholes and uniform distribution, and has high comprehensive performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of composite material preparation, and more particularly to a preparation method of high-performance carbon fiber 2.5D flat plates. BACKGROUND

[0002] With the development of the photovoltaic industry, traditional graphite materials are difficult to meet the large-scale needs of single-crystal furnace drawing furnaces and polycrystal ingot casting furnaces, C / C composite materials have more excellent heat preservation performance, higher strength and better toughness, and are not easy to break, so that the production energy consumption can be effectively reduced, the service life of equipment is improved, and the cost of the whole production is reduced. Therefore, heat preservation parts, structural parts and heating bodies made of C / C composite materials will be the development direction of heat field materials of photovoltaic equipment such as single-crystal silicon pulling furnaces and polycrystal ingot casting furnaces.

[0003] As known, C / C composite materials are composed of carbon fibers and matrix carbon. The structure includes the structure of carbon fibers, the structure of matrix carbon and the pore structure characteristics (the size, quantity, shape and distribution of pores), wherein the pore characteristics depend on the preparation process method of the C / C composite material preform. The C / C composite material preform is generally prepared into a 2.5D carbon fiber preform by using needle punching technology. At present, carbon cloth is laid, a layer of net tire is laid on the carbon cloth layer and then needle punching is performed, and the needle punching density and the interlayer density are controlled according to the product requirement volume density, the needle punching density is 15-45 needles / cm 2 , the interlayer density is 1-20 layers / 10mm; the fiber distribution is designed, the layers are stacked and needle punched to the product design size, finally the edges of the preform are processed to the required size of the product, and then the final product is obtained through deposition, impregnation, carbonization, high temperature and machining; in the process of preparing the preform by using the above process, the needle punching depth is fixed and unchangeable, the needle punching working section is long, and repeated needle punching can cause damage to the surface carbon cloth and the net tire, the maximum fiber grabbing amount and the maximum fiber length during needle punching cannot be guaranteed, the preform forms an inner dense and outer sparse structure, the surface volume density (needle punching density) of the product is small, the internal volume density (needle punching density) is large, pyrolytic carbon and resin carbon are attached to the surface of the product during the deposition and impregnation process, and finally the density distribution of the carbon-carbon finished product is uneven, the porosity is high, the fibers are easy to be damaged in the temperature rising and falling environment, cracks are easy to be generated, and the service life of the carbon-carbon composite material is directly affected. SUMMARY

[0004] In order to solve the problems that the C / C preform has large external needle holes and an inner dense and outer sparse structure, and thus the C / C finished product has high local porosity, uneven density and low comprehensive performance, the application provides a preparation method of high-performance carbon fiber 2.5D flat plates.

[0005] The application provides a preparation method of high-performance carbon fiber 2.5D flat plates, which adopts the following technical scheme:

[0006] A method for preparing a high-performance carbon fiber 2.5D flat plate, comprising the following steps:

[0007] S1, preparing carbon cloth and net tire;

[0008] S2, preparing a preform: laying a layer of carbon cloth and a layer of net tire as a unit layer on a foam pad, arranging the needles on the needle plate to needle each unit layer horizontally and vertically once, lowering the laying platform of the unit layer after one layer of needle is completed, laying the second unit layer and repeating the above needle operation; after determining the specifications of the needles, the total number of needles for each layer can be obtained according to the needle density, the number of needles, the needle frequency and the stepping speed of the needle plate are set, the first needle is used for needle, when the thickness of the plate after needle is greater than 6mm, the second needle is used, the distance from the first needle to the needle tip is shortened by 1-2mm compared with the first needle, the other hooks are adjusted to the needle tip position, the adjustment distance is equal to the distance from the first needle to the needle tip, and the needle hook angle of the second needle is adjusted by 5-6° smaller than that of the first needle, the needle frequency and the stepping speed are changed accordingly when the second needle is used for needle;

[0009] S3, obtaining a C / C flat plate by depositing, impregnating, carbonizing, high temperature and machining the fiber preform obtained above.

[0010] By using the above technical scheme, each layer is needle-punched by using the layer-by-layer stacking needle punching method, each layer is horizontally and vertically needle-punched once, the fiber structure of the unit layer is ensured to be compact, the laying platform of the unit layer is controlled to be lowered after one layer of needle is completed, the lowering height is consistent with the thickness of the unit layer after needle is completed, the lowering height of the platform is continuously increased with the gradual increase of the thickness of the preform, the number of unit layers pierced by the needle is controlled through the lifting of the platform, so that the needle density of each unit layer is consistent; meanwhile, the second needle has smaller needle resistance and larger fiber grabbing amount and fiber guiding length compared with the first needle when used for needle, the first needle and the second needle are used in cooperation, the damage of the bottom carbon cloth caused by needle and the pores caused thereby are reduced, the preform surface is free of bulges and floating hairs, the needle density on the surface of the preform and the needle density inside the preform are ensured to be consistent by setting the needle frequency and the stepping speed of different needles, the needle holes are uniformly distributed, which is beneficial to the subsequent carbon densification operation, the pyrolytic carbon and the resin carbon can be uniformly deposited on the product in the process of deposition and impregnation, the densification period is shortened, and finally the C / C finished product with uniform density is obtained, and the schematic diagram of the first needle and the second needle is shown in Figure 1 .

[0011] Optionally, the effective working section of the first needle is between 8-13mm, and the effective working section of the second needle is between 10-15mm.

[0012] The effective working section of the needle is the length of the needle minus the distance from the first insertion of the needle to the tip.

[0013] Optionally, the insertion depth of the needle is between 12-16 mm.

[0014] By adopting the above technical solution, when the insertion depth of the needle is controlled between 12-16mm, the internal fibers are less affected by the needle, and the fibers coordinate to bear the load during the load-bearing process, resulting in good toughness.

[0015] Optionally, in the acupuncture operation, once the needle specification is determined, the total number of acupuncture points per layer is a fixed value, calculated by the following formula:

[0016]

[0017] Where S is the product flat panel area, in cm² 2 ;

[0018] A represents the total number of needle punctures per layer;

[0019] d represents the number of times the unit layer is penetrated by the needle when the specified density is achieved. In actual calculations, it is represented by multiplying the effective working section of the needle by 2, where the effective working section of the needle is always measured in mm.

[0020] By adopting the above technical solution, once the size of the plate and the type of needle used are determined, the total number of needles in each layer of the needle unit can be determined according to the above formula. Based on the total number of needles in each layer, a suitable needle plate can be selected to arrange the needles reasonably.

[0021] Optionally, during the acupuncture operation, the acupuncture frequency and stepping speed are related as follows, depending on the total number of acupuncture points in each layer:

[0022]

[0023] Where B is the number of needles on the needle plate;

[0024] v is the step speed, mm / s;

[0025] C represents the side length of the product's flat panel, in mm;

[0026] After determining the total number of needles in each layer, the number of needles on the needle plate is set, and the relationship between the needle frequency and the stepping speed is obtained by formula. The parameters are set to perform needle puncture to obtain the carbon fiber preform.

[0027] By adopting the above technical solution, the needle density of each layer of the carbon fiber preform is controllable. Once the optimal needle density of the product is determined, the total number of needles in each layer can be calculated. Appropriate needles can be selected according to product requirements, and the number of needles on the needle plate can be set. Then, the appropriate stepping speed and needle frequency can be set according to the formula to achieve the optimal needle density of the product and control the needle density inside and outside the preform to be consistent.

[0028] Optionally, the needle frequency is between 2 and 6 needles per second.

[0029] By adopting the above technical solution, the stepping speed is determined after the acupuncture frequency is determined. Acupuncture can be performed by setting the parameters of the acupuncture machine. A suitable acupuncture frequency can reduce the wear of the acupuncture machine, ensure the output speed, and ensure the service life of the acupuncture needle.

[0030] Preferably, the areal density of the carbon cloth is 300-1000 g / m². 2 The areal density of the mesh tire is 50-150 g / m². 2 .

[0031] Preferably, the distance from the first insertion of the second needle to the needle tip is shortened by 2mm compared to the first needle, and all other hooks are adjusted towards the needle tip position. The adjustment distance is equal to the distance from the first insertion of the second needle to the needle tip, and the hook inclination angle of the second needle is 5° smaller than that of the first needle.

[0032] Preferably, when the plate thickness is greater than 6mm, for the front The first needle is used to perform acupuncture on the layer unit. The next unit layer is needled using a second needle.

[0033] By adopting the above technical solution, each unit layer is needled to form a board. When the board thickness is greater than 6mm, continuing to use the first needle will cause the two ends of the introduced Z-direction fiber to be held by the planar fiber, thereby restricting the movement of the needle. The force of the needle movement is greater than the strength of the fiber itself, resulting in breakage and damage. Through the cooperation of the second needle and the second needle, after the board thickness is greater than 6mm, the adjusted second needle is used to reduce the resistance when the needle is inserted, avoid the damage to the bottom carbon cloth caused by needle piercing, and avoid the situation of dense inside and sparse outside of the precast body caused by the continuous increase of the bottom layer density.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. Because the method of this application uses the first needle and the second needle alternately, the second needle is obtained by adjusting the first needle. The second needle has less needle-punching resistance than the first needle. While ensuring the maximum fiber grabbing amount and the maximum fiber drawing length, it avoids excessive damage to the bottom carbon cloth and the mesh. The final preform has a uniform and dense surface structure, and its pore size and distribution are more uniform.

[0036] 2. The method of this application is applicable to the preparation of preforms with a plate thickness greater than 6mm. When the plate thickness is greater than 6mm, the adjusted needle is used for needle punching, which avoids the continuous use of the same needle, which damages the carbon cloth and increases the bulk density of the bottom layer, forming a structure that is dense inside and sparse outside, thus obtaining a carbon fiber preform with consistent needle punching density inside and outside.

[0037] 3. In this method, the number of needle pricks per unit layer is controlled by the raising and lowering of the unit layer platform. The lowering height of the unit layer platform is consistent with the lowering height of the unit layer after needle pricks are completed, ensuring that all unit layers receive the same number of needle pricks, thereby ensuring consistent needle prick density inside and outside.

[0038] 4. The method of this application provides the relationship between the needle density and the total number of needles in each layer, as well as the stepping speed and needle frequency. Once the total number of needles in each layer is determined based on the needle density, the relationship between the stepping speed and needle frequency parameters on the needle punching machine is determined accordingly. By setting the needle frequency, the stepping speed required to achieve the specified needle density can be obtained. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the first and second needles in Embodiment 1 of this application;

[0040] Figure 2 The effect of different needle-punching densities on the shear strength of the preform;

[0041] Figure 3 The effect of different needle-punching densities on the bending strength of precast bodies;

[0042] Figure 4 The effect of different needle-punching densities on the tensile strength of the preform;

[0043] Figure 5 This is a comparison diagram of the macroscopic effects of the samples in Example 1.5 and Comparative Example 1 after acupuncture.

[0044] Figure 6 This is a comparison diagram of the macroscopic effects of Example 1.5 and Comparative Example 1 after one cycle of vapor phase deposition and liquid phase impregnation carbonization.

[0045] Figure 7This is a comparison SEM image of the samples from Example 1.5 and Comparative Example 1 after one cycle of vapor phase deposition and liquid phase impregnation carbonization. Detailed Implementation

[0046] The present application will be further described in detail below with reference to the embodiments.

[0047] The carbon fiber used is Toray 12K-T700SC, with a tensile strength of 4900 MPa and a linear density of 1.8 g / cm³. 3

[0048] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0049] Example

[0050] Example 1

[0051] Preparation of 800mm×800mm×40mm C / C flat plates: using carbon fiber cloth with a basis weight of 400g / m² 2 The net tire weight is 120g / m². 2 The first needle is a 14×16×36×3C333 model, with its first insertion distance from the needle tip being 3.18 mm and the hook angle being 15°. The second needle has its first insertion distance from the needle tip being 1.18 mm, and all other hooks are adjusted 1.18 mm towards the needle tip, with the hook angle being 10°. The effective insertion section of the first needle is 8.82 mm, the effective insertion section of the second needle is 10.82 mm, and the insertion depth is 12 mm.

[0052] Prepare carbon fiber fabric and weave: Load the carbon fiber warp yarns into the yarn frame, and use a unwinding machine to unwind the weft yarns. Set the appropriate parameters on the loom to obtain a weight of 400 g / m². 2 A 0.75mm thick carbon fiber cloth was used. The carbon fiber was loaded into a yarn rack, and a fiber cutter was used to cut the fibers into short fibers with a length of 7cm. The appropriate parameters for the mesh fabric machine were then set to obtain a basis weight of 120g / m². 2 0.5mm thick mesh tire;

[0053] A layer of carbon cloth and a layer of mesh are laid on the foam pad as a unit layer. The needles on the needle plate are arranged to needle each unit layer once horizontally and vertically. After one layer is needled, the platform for laying the unit layer is controlled to drop by 1 mm. The drop height is consistent with the thickness of the unit layer after needled. The needled operation is repeated when laying the second unit layer. The first needle is used for the first 6 layers, and the second needle is used for layers 7-40. The design parameters of needle density, needle frequency when using the first and second needles, and step speed are shown in Table 1.

[0054] Table 1 Parameters of needle-punched C / C preforms

[0055]

[0056]

[0057] The carbon fiber preform obtained above was placed in a deposition furnace and propylene was introduced at 1200℃ for 300 hours for deposition. Vapor deposition carbonization was then used to densify the preform to 1.2 ± 0.1 g / cm³. 3 After deposition, surface residue is cleaned, and the semi-finished product is immersed in phenolic resin to further densify to 1.5±0.1 g / cm³. 3 After impregnation is completed, the impregnated board is left to dry and placed in a high-pressure curing tank for 48 hours. The cured board is then placed in a carbonization furnace at 900°C for 50 hours. After carbonization, it is treated at 2100°C for 10 hours to obtain the C / C plate.

[0058] The mechanical properties of C / C plates prepared with different needle-punching densities were tested. The shear strength of the C / C plates was tested according to the standard method JC / T 773-2010, with the plates cut into 20mm × 10mm × 2mm specimens, a span of 10mm, and a testing speed of 1mm / min. The bending properties of the materials were tested according to the international standard ASTM C1341-00, with specimen dimensions of 75mm × 12mm × 4mm. Tensile strength tests were conducted on C / C plates cut into 80mm × 6.6mm × 3.6mm specimens using an MTS-100KN electronic universal testing machine with displacement loading at a loading speed of 2mm / min. 1mm thick aluminum reinforcing sheets were attached to both ends of the tensile specimens. The test results are shown in Table 2.

[0059] Table 2 Performance test results

[0060] Shear strength / Mpa Bending strength / Mpa Tensile strength / Mpa Example 1.1 8.2 82 61 Example 1.2 10.2 87 68 Example 1.3 13.4 91 76 Example 1.4 15.7 127 83 Example 1.5 18.3 146 102 Example 1.6 16.1 131 91 Example 1.7 14.5 101 80 Example 1.8 13.2 88 74 Example 1.9 11.0 72 71 Example 1.10 8.0 60 63

[0061] The above results are presented as a line chart, see... Figure 2-4 In conjunction with Examples 1.1-1.10 and Figure 2-4 It can be seen that as the knitting density increases, the shear strength, flexural strength, and tensile strength of the c / c flat plate show a trend of first increasing and then decreasing. When the needle density is 42 needles / cm², the strength decreases. 2 At the optimal time, its various properties are at their best. In this application, the optimal needle punching density is selected, so that the resulting C / C flat plate has the advantages of excellent mechanical properties and high fracture toughness. According to customer feedback, the service life of the fiber flat plate can be increased by 10% during use.

[0062] Example 2

[0063] Preparation of 800mm×800mm×40mm C / C flat plates: using carbon fiber cloth with a basis weight of 400g / m²2 The net tire weight is 120g / m². 2 The first needle is a 14×16×36×3C333 model, with its first insertion distance from the needle tip being 3.18mm and the hook angle being 15°. The second needle has its first insertion distance from the needle tip being 1.18mm, and all other hooks are adjusted 1.18mm towards the needle tip, with a hook angle of 9°. The effective working section of the first needle is 8.82mm, the effective working section of the second needle is 10.82mm, and the insertion depth is 12mm.

[0064] A method for preparing a high-performance 2.5D carbon fiber flat plate includes the following steps:

[0065] S1. Prepare carbon fiber cloth and mesh: Load the carbon fiber warp yarns into the yarn frame, and use a unwinding machine to unwind the weft yarns. Set the appropriate parameters for the loom to obtain a weight of 400 g / m². 2 A 0.75mm thick carbon fiber cloth was used. The carbon fiber was loaded into a yarn rack, and a fiber cutter was used to cut the fibers into short fibers with a length of 7cm. The appropriate parameters for the mesh fabric machine were then set to obtain a basis weight of 120g / m². 2 0.5mm thick mesh tire;

[0066] S2, Prefabrication: Using the aforementioned carbon cloth and mesh layer, lay one layer of carbon cloth and one layer of mesh on the foam pad as a unit layer. After needle punching, the thickness of each unit layer is 1mm. The product requires a thickness of 40mm, greater than 6mm. The first needle is used to needle punch the first 6 unit layers, according to the formula... The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between acupuncture frequency and stepping speed was obtained, and the acupuncture frequency was determined to be 4 needles / s, the stepping speed to be 10.50 mm / s, and one needle was inserted horizontally and vertically for each layer. After acupuncture, the platform dropped by 1 mm. A second needle was used to acupuncture layers 7-40, according to the formula. The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between the needling frequency and the stepping speed was obtained. The needling frequency of the needling machine was set to 3 needles / s, and the stepping speed was set to 10.05 mm / s. Each layer was needled once horizontally and once vertically. After needling, the platform dropped by 1 mm, and the next unit layer was laid and needling continued. The operation was repeated to obtain the carbon fiber preform. S3, the fiber preform obtained above was placed in a deposition furnace and propylene was introduced at 1200℃ for deposition for 300 h. The preform was densified to 1.2 ± 0.1 g / cm³ by vapor deposition carbonization. 3After deposition, surface residue is cleaned, and the semi-finished product is immersed in phenolic resin to further densify to 1.5±0.1 g / cm³. 3 After impregnation is completed, the impregnated board is left to dry and placed in a high-pressure curing tank for 48 hours. The cured board is then placed in a carbonization furnace at 900°C for 50 hours. After carbonization, it is treated at 2100°C for 10 hours to obtain the C / C plate.

[0067] Example 3

[0068] The difference from Example 2 is that in this example, the second needle is inserted 2.18mm from the needle tip, and the other needle hooks are all adjusted 2.18mm towards the needle tip.

[0069] A method for preparing a high-performance 2.5D carbon fiber flat plate includes the following steps:

[0070] S1. Prepare carbon fiber cloth and mesh: Load the carbon fiber warp yarns into the yarn frame, and use a unwinding machine to unwind the weft yarns. Set the appropriate parameters for the loom to obtain a weight of 400 g / m². 2 A 0.75mm thick carbon fiber cloth was used. The carbon fiber was loaded into a yarn rack, and a fiber cutter was used to cut the fibers into short fibers with a length of 7cm. The appropriate parameters for the mesh fabric machine were then set to obtain a basis weight of 120g / m². 2 0.5mm thick mesh tire;

[0071] S2, Prefabrication: Using the aforementioned carbon cloth and mesh layer, lay one layer of carbon cloth and one layer of mesh on the foam pad as a unit layer. After needle punching, the thickness of each unit layer is 1mm. The product requires a thickness of 40mm, greater than 6mm. The first needle is used to needle punch the first 6 unit layers, according to the formula... The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between acupuncture frequency and stepping speed was obtained, and the acupuncture frequency was determined to be 4 needles / s, the stepping speed to be 10.50 mm / s, and one needle was inserted horizontally and vertically for each layer. After acupuncture, the platform dropped by 1 mm. A second needle was used to acupuncture layers 7-40, according to the formula. The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between the needling frequency and the stepping speed was obtained. The needling frequency of the needling machine was set to 4 needles / s, and the stepping speed was set to 11.69 mm / s. Each layer was needled once horizontally and once vertically. After needling, the platform dropped by 1 mm, and the next unit layer was laid and needling continued. The operation was repeated to obtain the carbon fiber preform. S3, the fiber preform obtained above was placed in a deposition furnace and propylene was introduced at 1200℃ for deposition for 300 h. The preform was densified to 1.2 ± 0.1 g / cm³ by vapor deposition carbonization. 3 After deposition, surface residue is cleaned, and the semi-finished product is immersed in phenolic resin to further densify to 1.5±0.1 g / cm³. 3 After impregnation is completed, the impregnated board is left to dry and placed in a high-pressure curing tank for 48 hours. The cured board is then placed in a carbonization furnace at 900°C for 50 hours. After carbonization, it is treated at 2100°C for 10 hours to obtain the C / C plate.

[0072] Example 4

[0073] The difference from Example 3 is that the hook angle of the second needle used in this example is 10°.

[0074] Example 5

[0075] Preparation of 800mm×800mm×40mm C / C flat plates: using carbon fiber cloth with a basis weight of 400g / m² 2 The net tire weight is 120g / m². 2 The first needle is a 15×16×36×3M333, with its first insertion distance from the needle tip being 4.8mm and the hook angle being 15°. The second needle has its first insertion distance from the needle tip being 2.8mm, and all other hooks are adjusted 2.8mm towards the needle tip, with the hook angle being 10°. The effective working section of the first needle is 11.2mm, the effective working section of the second needle is 13.2mm, and the insertion depth is 16mm.

[0076] A method for preparing a high-performance 2.5D carbon fiber flat plate includes the following steps:

[0077] S1. Prepare carbon fiber cloth and mesh: Load the carbon fiber warp yarns into the yarn frame, and use a unwinding machine to unwind the weft yarns. Set the appropriate parameters for the loom to obtain a weight of 400 g / m². 2 A 0.75mm thick carbon fiber cloth was used. The carbon fiber was loaded into a yarn rack, and a fiber cutter was used to cut the fibers into short fibers with a length of 7cm. The appropriate parameters for the mesh fabric machine were then set to obtain a basis weight of 120g / m². 2 0.5mm thick mesh tire;

[0078] S2, Prefabrication: Using the aforementioned carbon cloth and mesh layer, lay one layer of carbon cloth and one layer of mesh on the foam pad as a unit layer. After needle punching, the thickness of each unit layer is 1mm. The product requires a thickness of 40mm, greater than 6mm. The first needle is used to needle punch the first 6 unit layers, according to the formula... The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between acupuncture frequency and stepping speed was obtained, and the acupuncture frequency was determined to be 4 needles / s, the stepping speed to be 8.57 mm / s, and one needle was inserted horizontally and vertically for each layer. After acupuncture, the platform dropped by 1 mm. A second needle was used to acupuncture layers 7-40, according to the formula. The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between the needling frequency and the stepping speed was obtained. The needling frequency of the needling machine was set to 4 needles / s, and the stepping speed was set to 10.95 mm / s. Each layer was needled once horizontally and once vertically. After needling, the platform dropped by 1 mm, and the next unit layer was laid and needling continued. The operation was repeated to obtain the carbon fiber preform. S3, the fiber preform obtained above was placed in a deposition furnace and propylene was introduced at 1200℃ for deposition for 300 h. The preform was densified to 1.2 ± 0.1 g / cm³ by vapor deposition carbonization. 3 After deposition, surface residue is cleaned, and the semi-finished product is immersed in phenolic resin to further densify to 1.5±0.1 g / cm³. 3 After impregnation is completed, the impregnated board is left to dry and placed in a high-pressure curing tank for 48 hours. The cured board is then placed in a carbonization furnace at 900°C for 50 hours. After carbonization, it is treated at 2100°C for 10 hours to obtain the C / C plate.

[0079] Example 6

[0080] Preparation of 1000mm×1000mm×60mm C / C flat plates: using carbon fiber cloth with a basis weight of 300g / m² 2 The net tire weight is 50g / m². 2 The first needle is a 14×16×36×3C333 model, with its first insertion distance from the needle tip being 3.18mm and the hook angle being 15°. The second needle has its first insertion distance from the needle tip being 1.18mm, and all other hooks are adjusted 1.18mm towards the needle tip, with the hook angle being 10°. The effective working section of the first needle is 8.82mm, the effective working section of the second needle is 10.82mm, and the insertion depth is 12mm.

[0081] A method for preparing a high-performance 2.5D carbon fiber flat plate includes the following steps:

[0082] S1. Prepare carbon fiber cloth and mesh: Load the carbon fiber warp yarns into the yarn frame, and use a unwinding machine to unwind the weft yarns. Set the appropriate parameters for the loom to obtain a weight of 300 g / m². 2 A carbon fiber cloth with a thickness of 0.58 mm was used. The carbon fiber was loaded into a yarn frame, and a fiber cutter was set to cut the fibers to obtain short fibers with a length of 7 cm. The corresponding parameters of the web-forming machine were set to obtain a weight of 50 g / m². 2 The mesh tire has a thickness of 0.18mm;

[0083] S2, Prefabrication: Using the aforementioned carbon cloth and mesh, lay one layer of carbon cloth and one layer of mesh on the foam pad as a unit layer. After needle punching, the thickness of each unit layer is 0.6mm. The product requires a thickness of 60mm, greater than 6mm. The first needle is used to prepare the prefabricated body. Acupuncture is performed on the first 10 layers of unit cells, according to the formula. The total number of needles in each layer was calculated. The needles are arranged in two rows on a needle plate, with a total of 50 needles. The relationship between acupuncture frequency and stepping speed was obtained, and the acupuncture frequency was determined to be 4 needles / s, the stepping speed to be 12.16 mm / s, and one needle was inserted horizontally and vertically for each layer. After acupuncture, the platform dropped by 0.9 mm. A second needle was used to acupuncture layers 8-60, according to the formula. The total number of needles in each layer was calculated. The needles (rounded to the nearest integer) are used. The needle punching frequency is set to 6 punches / s, and the needle punching machine stepping speed is 14.33 mm / s. Each layer is needled once horizontally and once vertically. After the needle punching is completed, the platform drops by 0.9 mm. The next unit layer is laid and needle punching is continued. The operation is repeated to obtain the carbon fiber preform.

[0084] S3, the fiber preform obtained above is placed in a deposition furnace and natural gas is introduced to deposit it at 1200℃ for 300 hours. The preform is densified to 1.2±0.1 g / cm³ by vapor deposition carbonization. 3 After deposition, surface residue is cleaned, and the semi-finished product is immersed in furan resin to further densify to 1.5±0.1 g / cm³. 3 After impregnation is completed, the impregnated board is left to dry and placed in a high-pressure curing tank for 48 hours. The cured board is then placed in a carbonization furnace at 900°C for 50 hours. After carbonization, it is treated at 2200°C for 10 hours to obtain the C / C plate.

[0085] Comparative Example

[0086] Comparative Example 1

[0087] Preparation of 800mm×800mm×40mm C / C flat plates: using carbon fiber cloth with a basis weight of 400g / m²2 The net tire weight is 120g / m². 2 The needle used is model 14×16×36×3C333, with the first puncture distance from the needle tip being 3.18mm and the hook angle being 15°.

[0088] A method for preparing a high-performance 2.5D carbon fiber flat plate includes the following steps:

[0089] S1. Prepare carbon fiber cloth and mesh: Load the carbon fiber warp yarns into the yarn frame, and use a unwinding machine to unwind the weft yarns. Set the appropriate parameters for the loom to obtain a weight of 400 g / m². 2 A 0.75mm thick carbon fiber cloth was used. The carbon fiber was loaded into a yarn rack, and a fiber cutter was used to cut the fibers into short fibers with a length of 7cm. The appropriate parameters for the mesh fabric machine were then set to obtain a basis weight of 120g / m². 2 0.5mm thick mesh tire;

[0090] S2, Preparing the preform: A layer of carbon cloth and a layer of mesh are laid on the foam pad as a unit layer. The unit layer is then needled with needles at a depth of 12 mm and a needle density of 42 needles / cm². 2 Needling is performed once horizontally and once vertically on each layer. After needleding, the thickness of each unit layer is 1mm. The next unit layer is then laid and needled again to obtain the fiber preform.

[0091] S3, the fiber preform obtained above is placed in a deposition furnace and propylene is introduced at 1200℃ for 300 hours for deposition. Vapor deposition is then used to increase the carbon density of the preform to 1.2 ± 0.1 g / cm³. 3 After deposition, surface residue is cleaned, and the semi-finished product is immersed in phenolic resin to further densify to 1.5±0.1 g / cm³. 3 After impregnation is completed, the impregnated board is left to dry and placed in a high-pressure curing tank for 48 hours. The cured board is then placed in a carbonization furnace at 900°C for 50 hours. After carbonization, it is treated at 2100°C for 10 hours to obtain the C / C plate.

[0092] Comparative Example 2

[0093] Preparation of 800mm×800mm×40mm C / C flat plates: using carbon fiber cloth with a basis weight of 400g / m² 2 The net tire weight is 120g / m². 2The first needle is a 14×16×36×3C333 model, with its first insertion distance from the needle tip being 3.18mm and the hook angle being 15°. The second needle has its first insertion distance from the needle tip being 1.18mm, and all other hooks are adjusted 1.18mm towards the needle tip, with the hook angle being 10°. The effective working section of the first needle is 8.82mm, the effective working section of the second needle is 10.82mm, and the insertion depth is 12mm.

[0094] A method for preparing a high-performance 2.5D carbon fiber flat plate includes the following steps:

[0095] S1. Prepare carbon fiber cloth and mesh: Load the carbon fiber warp yarns into the yarn frame, and use a unwinding machine to unwind the weft yarns. Set the appropriate parameters for the loom to obtain a weight of 400 g / m². 2 A 0.75mm thick carbon fiber cloth was used. The carbon fiber was loaded into a yarn rack, and a fiber cutter was used to cut the fibers into short fibers with a length of 7cm. The appropriate parameters for the mesh fabric machine were then set to obtain a basis weight of 120g / m². 2 0.5mm thick mesh tire;

[0096] S2, Prefabrication: Using the aforementioned carbon cloth and mesh layer, lay one layer of carbon cloth and one layer of mesh on the foam pad as a unit layer. After needle punching, the thickness of each unit layer is 1mm. Use the first needle to punch the first 10 unit layers, according to the formula... The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between acupuncture frequency and stepping speed was obtained, and the acupuncture frequency was determined to be 4 needles / s, the stepping speed to be 10.50 mm / s, and each layer was needled once horizontally and once vertically. After acupuncture, the platform dropped by 1 mm. A second needle was used to needle layers 10-40, according to the formula. The total number of needles in each layer was calculated. Needles (rounded to the nearest integer), set up 2 rows of needle plates, with a total of 50 needles, according to The relationship between the needle punching frequency and the stepping speed was obtained. The needle punching frequency of the needle punching machine was set to 3 punches / s and the stepping speed was set to 10.05 mm / s. Each layer was needled once horizontally and once vertically. After the needle punching was completed, the platform dropped by 1 mm and the next unit layer was laid to continue needle punching. The operation was repeated to obtain the carbon fiber preform.

[0097] S3, the fiber preform obtained above is placed in a deposition furnace and propylene is introduced at 1200℃ for 300 hours for deposition. Vapor deposition is then used to increase the carbon density of the preform to 1.2 ± 0.1 g / cm³. 3 After deposition, surface residue is cleaned, and the semi-finished product is immersed in phenolic resin to further densify to 1.5±0.1 g / cm³.3 After impregnation is completed, the impregnated board is left to dry and placed in a high-pressure curing tank for 48 hours. The cured board is then placed in a carbonization furnace at 900°C for 50 hours. After carbonization, it is treated at 2100°C for 10 hours to obtain the C / C plate.

[0098] Performance testing

[0099] Detection methods / test methods

[0100] Apparent structure

[0101] The apparent structure and surface morphology of Example 1.5 and Comparative Example 1 before and after one cycle of carbonization were observed. The flatness and uniformity of the C / C flat plate manufactured in Example 1.5 were higher than those in Comparative Example 1. Furthermore, the apparent structure of Example 1.5 was uniform and dense, with no obvious pores or microcracks, and no loose fibers or bulges. Its microstructure also clearly showed that the fiber arrangement, carbon layer deposition, and pore size and distribution were more uniform. (See Appendix) Figure 5-7 Observation of the surface structure of Examples 2-6 revealed no obvious pores or microcracks, no bulging or floating hairs, indicating that by selecting different specifications of needles, different weights of carbon cloth and mesh, and changing the insertion depth, the method of this application can obtain C / C plates with small, uniform, and dense pores.

[0102] Mechanical properties of Examples 2-5 and Comparative Examples 1-2 were tested, including shear strength, flexural strength and tensile strength. The results are shown in Table 3.

[0103] Table 3 Performance test results

[0104] Shear strength / Mpa Bending strength / Mpa Tensile strength / Mpa Example 2 18.2 144 99 Example 3 17.9 140 95 Example 4 18.0 141 96 Example 5 18.1 142 98 Comparative Example 1 14.2 129 86 Comparative Example 2 16.0 136 91

[0105] Combining Examples 1.5, Examples 2-5 and Comparative Example 1, and referring to Tables 2 and 3, it can be seen that the test data of Examples 1.5 and Examples 2-5 are all better than those of Comparative Example 1. This indicates that the C / C flat plate prepared by the method of needle punching with the first and second needles of this application has better mechanical properties. During the preparation process, the needles cause less damage to the carbon fiber, the needle holes are more uniformly distributed, and the density is better.

[0106] Combining Example 1.5 and Comparative Example 2 with Tables 2 and 3, it can be seen that the performance of Example 1.5 is better than that of Comparative Example 2. This indicates that when the thickness of the board is greater than 6 mm, continuing to use the first needle will cause some fibers to break and be damaged, thereby affecting the mechanical properties of the C / C board.

[0107] Combining Examples 1.5 and 2-4 with Tables 2 and 3, it can be seen that when the distance from the first insertion of the second needle to the needle tip is shortened by 2 mm compared to the first needle, and the tilt angle is reduced by 5°, the resulting c / c plate exhibits the best mechanical properties.

[0108] Combining Examples 1.5 and 5 with Tables 2 and 3, it can be seen that the c / c plates prepared when the needle penetration depth is between 12-16 mm all have good shear, bending and tensile strength.

[0109] Example 6 uses carbon cloth and mesh with different weights than Examples 1-5, which has a significant impact on mechanical properties and is not compared.

[0110] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for producing a high-performance carbon fiber 2.5D flat panel, characterized by, It comprises the following steps: S1, preparing carbon cloth and net tire; S2, preparing a preform: laying a layer of carbon cloth and a layer of net tire as a unit layer on a foam pad, arranging the needles on the needle plate to needle each unit layer horizontally and vertically once, lowering the platform for laying the unit layer after one layer of needle is completed, and the lowering height is consistent with the thickness of the unit layer after the needle is completed, laying the second unit layer and repeating the above needle operation; when the specifications of the needles are determined, the total number of needles for each layer can be obtained according to the needle density, the number of needles on the needle plate, the needle frequency and the step speed are set, the first needle is used for needle, when the thickness of the plate after needle is greater than 6mm, the second needle is used, the distance from the first needle to the needle tip is shortened by 1-2mm, the other hooks are adjusted to the needle tip position, the adjustment distance is equal to the distance from the first needle to the needle tip, and the needle hook angle of the second needle is adjusted by 5-6° smaller than that of the first needle, the needle frequency and the step speed are changed accordingly when the second needle is used for needle; S3, obtaining a C / C flat plate by depositing, impregnating, carbonizing, high temperature and machining treatment on the obtained fiber preform.

2. The method for preparing a high-performance 2.5D carbon fiber flat plate according to claim 1, characterized in that: The effective working section of the first needle is between 8-13mm, and the effective working section of the second needle is between 10-15mm.

3. The method of claim 1, wherein the high-performance carbon fiber 2.5D panel is prepared by the steps of: The penetration depth of the first needle and the second needle is between 12-16mm. ​ 4. The method of claim 1, wherein the high-performance carbon fiber 2.5D panel is prepared by the steps of: In the needle operation, when the specifications of the needles are determined, the total number of needles for each layer is a determined value, which is calculated by the following formula: ​ ； wherein 42 is the optimum needling density, stabs / cm 2 ; S is the product flat area, cm 2 ; A is the total number of needles for each layer, and d is the number of times the unit layer is penetrated by the needle to reach the specified density, which is represented by the value of the effective working section of the needle multiplied by 2 in actual calculation, wherein the unit of the effective working section of the needle is mm. In the needle operation, according to the total number of needles for each layer, the needle frequency and the step speed have the following relationship:

5. The method of claim 1-4, wherein the method is characterized by: Wherein, B is the number of needles on the needle plate, and C is the length of the product flat plate, mm; ； N is the needle frequency, and v is the step speed, mm / s; When the total number of needles for each layer is determined, the number of needles on the needle plate is set, the relationship between the needle frequency and the step speed is obtained by the formula, and the parameters are set for needle to obtain the carbon fiber preform. The needle frequency is between 2-6 needles / s. The distance from the first needle to the needle tip is shortened by 2mm, and the other hooks are adjusted to the needle tip position, the adjustment distance is equal to the distance from the first needle to the needle tip, and the needle hook angle of the second needle is adjusted by 5° smaller than that of the first needle. ​ 6. The method of claim 5, wherein the high-performance carbon fiber 2.5D panel is prepared by the steps of: ​ ​ 7. The method of claim 1, wherein the high-performance carbon fiber 2.5D panel is prepared by the steps of: The areal density of the carbon cloth is 300-1000 g / m 2 The areal density of the web is 50-150 g / m 2 . ​ 8. The method of claim 1, wherein the high performance carbon fiber 2.5D panel is prepared by the steps of: ​ ​ 9. The method for preparing a high-performance carbon fiber 2.5D flat plate according to claim 1, characterized in that: When the thickness of the board is greater than 6 mm, the front layer unit layer is needled using the first needle, and the subsequent unit layer is needled using the second needle.

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