A composite carbon-carbon composite material and preparation method thereof

Abstract

The present invention belongs to the field of composite materials, and specifically relates to a composite carbon-carbon composite material and a preparation method thereof. The present invention cuts carbon fiber or modified carbon fiber into short pieces, combs them, obtains carbon fiber meshes with different weights and densities, and then adds carbon cloths with different weights for needle punching. The carbon fiber needle-punched layer has at least 3 units, including upper, middle and lower unit layers, which are cyclically stacked in sequence according to the thickness of the product and then needle-punched to form. The present invention composites a mesh needle-punched carbon-carbon composite material and a carbon cloth carbon-carbon composite material structure. The prepared material has both a mesh needle-punched structure and a carbon cloth laminated structure, has high strength, relatively uniform density, is not easy to delaminate, and can effectively increase the densification rate.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon-carbon composite materials, and in particular to a composite carbon-carbon composite material and a preparation method thereof. Background Art

[0002] Carbon-carbon composite materials have the advantages of low density, high strength, anti-oxidation, and high temperature resistance. In recent years, with the continuous deepening of relevant research, carbon-carbon composite materials have gradually developed from military and aerospace applications to civilian industrial fields such as photovoltaics, automobile manufacturing, and medical treatment. The demand for them is also steadily increasing. Therefore, a stable preparation method suitable for large-scale production is needed. The carbon fiber needle-punched preform is a quasi-three-dimensional structure. In the vertical direction, the carbon fiber continuously runs through the entire vertical structure to form a whole. The three-dimensional fabric preform improves the interlayer shear force and interlayer thermal conductivity of the product, making it have the performance of a 3D woven preform and overcoming the disadvantages of complex 3D weaving process and high cost.

[0003] There are two main categories of carbon-carbon composite materials available on the market: one is a mesh needle-punched carbon-carbon composite material, and the other is a carbon cloth carbon-carbon composite material. The disadvantage of the mesh needle-punched carbon-carbon composite material is that during the needling process, the needle will pierce the carbon fiber and leave a large number of needle holes, which will affect the strength of the material, especially in the case of thin thickness, the compressive strength and bending strength are poor. Because it needs to go through the overall needling process, especially when making certain cylinders or crucible products, the production time is relatively long, and the product production cycle is long. The disadvantage of the carbon cloth type carbon-carbon composite material is that the simple carbon cloth is laminated and pressed, which is prone to delamination and cracking. And the surface of the carbon cloth is too dense, and it is difficult to increase the density through liquid or gas phase penetration, which is prone to uneven density distribution, resulting in uneven distribution of material mechanical strength. Since the materials made by this process are basically made of carbon fiber cloth laminated, the price of carbon fiber cloth is relatively high, resulting in a high cost of carbon-carbon composite materials made by this process, especially high-density materials, which require greater pressure to press more layers of carbon fiber cloth, and the cost is further increased. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a composite carbon-carbon composite material and a preparation method thereof, which can effectively solve the above-mentioned problems of the prior art.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A composite carbon-carbon composite material comprises a carbon fiber cloth and a carbon fiber web, wherein the carbon fiber cloth and the carbon fiber web are formed by plying and integrally needling; the carbon fiber web comprises a low-weight web and a high-weight web, the weights of which are 40-90 gsm and 90-140 gsm, respectively, and the densities of which are 0.10-0.3 g / cm³ and 0.3-0.5 g / cm³, respectively; the carbon fiber cloth comprises a 12K plain unidirectional carbon fiber cloth (200-400 gsm) and a plain carbon fiber cloth (300-600 gsm).

[0006] The layering method is to first use a low-weight, low-density mesh tire (40-90 gsm, 0.10-0.3 g / cm³) and a 12K, 200-400 gsm plain unidirectional carbon fiber cloth layer; in the middle, a high-weight, high-density mesh tire (90-140 gsm, 0.3-0.5 g / cm³) and a 12K, 300-600 gsm plain carbon fiber cloth layer; finally, a low-weight, low-density mesh tire (40-90 gsm, 0.10-0.3 g / cm³) and a 12K, 200-400 gsm plain unidirectional carbon fiber cloth layer.

[0007] A method for preparing the composite carbon-carbon composite material comprises the following steps: Preparing a carbon fiber web (S1): obtaining a carbon fiber web with different weights and densities by chopping and combing carbon fiber or modified carbon fiber, wherein the length of the chopped carbon fiber is 70-200 mm; Layup (S2): First use a low-weight, low-density mesh (40-90 gsm, 0.10-0.3 g / cm³) and 12K, 200-400 gsm plain weave unidirectional carbon fiber cloth for laying; The middle layer is a high-weight, high-density mesh tire (90-140 gsm, 0.3-0.5 g / cm³) and a 12K, 300-600 gsm plain carbon fiber cloth layer; Finally, use low-weight, low-density mesh (40-90 gsm, 0.10-0.3 g / cm³) and 12K, 200-400gsm plain unidirectional carbon fiber cloth for laying; Needle punching (S3): the sample prepared in step S2 is needle punched layer by layer to form a composite needle punched preform; Resin impregnation (S4): Infusing the composite needle-punched preform prepared in step S3 with a resin by vacuum impregnation, wherein the resin is a phenolic resin, furan resin or epoxy resin; After impregnation, hot pressing and curing are performed; Carbonization and graphitization (S5).

[0008] Liquid phase infiltration method: In a vacuum, the carbon-carbon composite material blank is infiltrated with resin, the resin is infiltrated for 2-12 hours, and then the resin is cured at a high temperature of 160-180°C.

[0009] In step S3, the acupuncture density is 20-40 needles / cm 2 , the needle penetration depth is 0.8-1.5 cm, the preform thickness is 12-15 mm, and the density is 0.4-0.7 g / cm³.

[0010] In step S4, hot pressing curing: temperature is 160-180°C, curing time is 6-8 h, and pressure is 16-18 MPa; In step S5, carbonization: temperature is 1400-1600°C; Graphitization: temperature is 2000-2200℃.

[0011] During the resin impregnation process, KH550 silane coupling agent is further added as a functional agent, and its mass is 1%-5% of the resin content.

[0012] Beneficial Effects

[0013] The present invention achieves significant improvements in performance and production efficiency of carbon-carbon composite materials through innovative carbon fiber needle-punched preform structure design and optimized preparation process, which is specifically reflected in the following aspects: 1. In the process of gas phase or liquid phase densification, the present invention effectively avoids the problem of carbon deposits blocking the holes on the product surface, making the density of different parts of the product more uniform. This design significantly improves the densification rate, reduces the number of densification times, avoids quality problems such as stratification, and improves the overall performance and reliability of the product.

[0014] 2. By adopting a structure in which the middle layer is a mesh tire and carbon cloth with a larger gram weight, and the bottom and top layers are a mesh tire and carbon cloth with a smaller gram weight, the present invention further optimizes the pore structure on the surface of the product during the liquid phase deposition densification process. This design not only makes the density of each part of the product more balanced, but also effectively improves the densification rate, reduces the number of densification times, and reduces the occurrence of quality problems such as delamination.

[0015] 3. The present invention combines the mesh needle-punched carbon-carbon composite material with the carbon cloth carbon-carbon composite material structure, combining the advantages of both and making up for their respective shortcomings. This composite structure not only improves the strength of the material, but also makes the density distribution more uniform, further enhances the product's anti-stratification ability, and effectively improves the densification rate.

[0016] 4. The preparation method of the present invention has the characteristics of low cost and short cycle, can effectively improve product performance and reduce later processes. This optimized process flow is particularly suitable for industrial production and has significant economic benefits and market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a graph showing the bending strength test results of the products obtained in Comparative Example 1, Example 1, and Example 2.

[0018] Figure 2 This is a graph showing the compressive strength test results of the products obtained in Comparative Example 1, Example 1, and Example 2. DETAILED DESCRIPTION

[0019] Comparative Example 1

[0020] Preparation method of composite carbon-carbon composite material: 1. Preparation of low-weight mesh

[0021] Provide Toray T700-12K carbon fiber precursor with a carbon content of ≥95%. The carbon fiber precursor is cut into short carbon fiber, which is combed into hair by a carding machine and then prepared into a low-weight mesh. The average length of the short carbon fiber is 15 mm, the weight of the low-weight mesh is 60 gsm, and the density is 0.40 g / cm³.

[0022] 2. Preparation of carbon fiber needle-punched preforms with the same density

[0023] Preparation of low-weight unit: a layer of low-weight mesh and a layer of carbon cloth are needle-punched to form a low-weight unit.

[0024] Layer-by-layer needling: Based on low-weight units, layers are laid layer by layer and needle-punched to prepare carbon fiber needle-punched preforms with the same density.

[0025] Acupuncture parameters: acupuncture density is 30 needles / cm 2 The needle insertion depth is 14 mm.

[0026] Carbon cloth parameters: 12K, 400 gsm plain weave carbon fiber cloth is used.

[0027] Preform parameters: The final prepared carbon fiber needle-punched preform has a thickness of 9 mm and a density of 0.3 g / cm³.

[0028] 3. Preparation of resin glue

[0029] Resin selection: Thermosetting resin is used as the matrix material.

[0030] Functional agent addition: KH560 silane coupling agent is added to the resin as a functional agent, and its usage amount is 3% of the mass of the phenolic resin.

[0031] Preparation of resin glue: Mix the functional agent and resin evenly to prepare resin glue.

[0032] 4. Preparation of carbon-carbon composite precursors

[0033] Vacuum impregnation: Place the carbon fiber needle-punched preform into the vacuum impregnation equipment to allow the resin glue to fully infiltrate the preform.

[0034] Curing treatment: Take out the preform after dipping and perform hot pressing curing treatment. The curing conditions are: temperature 170, curing time 7 hours, pressure 16 MPa.

[0035] Precursor preparation: After curing, a carbon-carbon composite material precursor is prepared.

[0036] Example 1

[0037] The remaining steps are carried out according to Comparative Example 1, except that the following steps are slightly different: 1. Preparation of low-weight mesh

[0038] Toray T700-12K carbon fiber precursor was selected, with a carbon content of ≥95%. The carbon fiber precursor was cut into short-cut carbon fibers, with an average length of 150 mm. Subsequently, the short-cut carbon fibers were combed into filaments by a carding machine, and further prepared into a low-weight mesh tire. The low-weight mesh tire has a gram weight of 60 gsm and a density of 0.20 g / cm³.

[0039] 2. Preparation of high-weight mesh

[0040] Toray T700-12K carbon fiber precursor is also used, with a carbon content of ≥95%. The carbon fiber precursor is cut into short carbon fibers, and the average length of the short carbon fibers is 150 mm. The short carbon fibers are combed into filaments by a carding machine, and further prepared into a high-weight mesh. The high-weight mesh has a gram weight of 120 gsm and a density of 0.40 g / cm³.

[0041] 3. Preparation of carbon fiber needle punched preform

[0042] Laying order: Bottom layer: A low-weight, low-density mesh (60 gsm, 0.20 g / cm³) layered with 12K, 300 gsm plain weave unidirectional carbon fiber cloth.

[0043] Middle layer: Use high-weight, high-density mesh (120 gsm, 0.40 g / cm³) and 12K, 500 gsm plain weave carbon fiber cloth for layering.

[0044] Top layer: Again a low weight, low density web (60 gsm, 0.20 g / cm³) laid up with 12K, 300 gsm plain weave UD carbon fiber fabric.

[0045] Acupuncture treatment: The three layers of samples were acupunctured layer by layer, with a density of 30 needles / cm 2 The acupuncture depth was 1.3 cm.

[0046] Preform parameters: The final prepared composite needle-punched preform has a thickness of 13 mm and a density of 0.6 g / cm³.

[0047] Example 2 Based on Example 1, the difference is that the resin used is phenolic resin, and the amount of KH550 silane coupling agent used in the resin glue is 2% of the mass of the phenolic resin.

[0048] Performance test: Using the Archimedes drainage method, the density of the carbon-carbon composite material after each carbonization and high-pressure liquid phase impregnation cycle was tested. The test results are shown in Table 1: Initial density of needle punched preform The first densification Second densification The third densification The 4th Densification Comparative Example 1 0.45 0.88 1.06 1.22 1.36 Example 1 0.50 0.96 1.15 1.36 1.48 Example 2 0.51 0.97 1.20 1.41 1.52 Table 1 Density of carbon-carbon composite materials (g / cm 3 ) Performance test: Determination of flexural strength of carbon-carbon composite materials: The carbon-carbon composite materials prepared in Examples 1-3 were tested for flexural strength using a Sansi CMT-5205 universal testing machine. The size of the sample was 100 mm × 12 mm × 8 mm. The test results are detailed in Figure 1 .

[0049] Performance test: Compressive strength test: The carbon-carbon composite materials prepared in Examples 1-3 were tested for compressive strength using a Sansi CMT-5205 universal testing machine. The size of the sample was 30 mm x 10 mm x 10 mm. The test results are detailed in Figure 2 The compressive strength σ of the composite material is calculated as follows: σ = (P) / (A) Where: σ-compressive strength, in megapascals (MPa); P-maximum load at failure, in Newton (N); A- The original cross-sectional area of ​​the specimen, in square millimeters (mm 2 ).

Claims

1. A composite carbon-carbon composite material, comprising a carbon fiber cloth and a carbon fiber web, characterized in that: The carbon fiber cloth and the carbon fiber mesh are formed by layering and integral needle punching; the carbon fiber mesh comprises a low-weight mesh and a high-weight mesh, the weights of which are 40-90 gsm and 90-140 gsm, respectively, and the densities of which are 0.10-0.3 g / cm³ and 0.3-0.5 g / cm³, respectively; the carbon fiber cloth comprises a 12K plain unidirectional carbon fiber cloth (200-400 gsm) and a plain carbon fiber cloth (300-600 gsm).

2. The composite carbon-carbon composite material according to claim 1, characterized in that: The layering method is to first use a low-weight, low-density mesh tire (40-90 gsm, 0.10-0.3 g / cm³) and a 12K, 200-400 gsm plain unidirectional carbon fiber cloth layer; in the middle, a high-weight, high-density mesh tire (90-140 gsm, 0.3-0.5 g / cm³) and a 12K, 300-600 gsm plain carbon fiber cloth layer; finally, a low-weight, low-density mesh tire (40-90 gsm, 0.10-0.3 g / cm³) and a 12K, 200-400gsm plain unidirectional carbon fiber cloth layer.

3. A method for preparing a composite carbon-carbon composite material as claimed in claim 1 or 2, characterized in that: The preparation method comprises the following steps: Preparing a carbon fiber web (S1): obtaining a carbon fiber web with different weights and densities by chopping and combing carbon fiber or modified carbon fiber, wherein the length of the chopped carbon fiber is 70-200 mm; Laying (S2): First use low-weight, low-density mesh (40-90 gsm, 0.10-0.3 g / cm³) and 12K, 200-400gsm plain weave unidirectional carbon fiber cloth; The middle layer is a high-weight, high-density mesh tire (90-140 gsm, 0.3-0.5 g / cm³) and a 12K, 300-600 gsm plain carbon fiber cloth layer; Finally, a low-weight, low-density mesh (40-90 gsm, 0.10-0.3 g / cm³) and 12K, 200-400 gsm plain unidirectional carbon fiber cloth are used for laying; Needle punching (S3): the sample prepared in step S2 is needle punched layer by layer to form a composite needle punched preform; Resin impregnation (S4): Infusing the composite needle-punched preform prepared in step S3 with a resin by vacuum impregnation, wherein the resin is a phenolic resin, furan resin or epoxy resin; After impregnation, hot pressing and curing are performed; Carbonization and graphitization (S5).

4. The method for preparing a composite carbon-carbon composite material according to claim 3, characterized in that: In step S3, the acupuncture density is 20-40 needles / cm 2 , the needle penetration depth is 0.8-1.5 cm, the preform thickness is 12-15 mm, and the density is 0.4-0.7g / cm³.

5. The method for preparing a composite carbon-carbon composite material according to claim 3, characterized in that: In step S4, hot pressing curing: temperature is 160-180°C, curing time is 6-8 h, and pressure is 16-18 MPa; In step S5, carbonization: temperature is 1400-1600°C; Graphitization: temperature is 2000-2200℃.

6. The method for preparing a composite carbon-carbon composite material according to claim 3, characterized in that: During the resin impregnation process, KH550 silane coupling agent is further added as a functional agent, and its mass is 1%-5% of the resin content.

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