Carbon-carbon composite material preform and preparation method thereof

Abstract

The present invention discloses a carbon-carbon composite material preform and a preparation method thereof, which relates to the technical field of composite materials. The pores of the preform are filled with short-cut fibers, and the density of the obtained preform is increased. Compared with the traditional carbon fiber preform, the density of the preform is deposited to 1.6g / cm 3 The carbon-carbon composite material preparation cycle can be shortened by approximately 50%. Oblique needling of the preform, including the chopped fiber filling, increases the number of fibers in the preform's longitudinal direction, converting fiber shearing into fiber tension. This significantly improves the preform's interlaminar shear performance, increasing the interlaminar shear strength of the deposited carbon-carbon composite material by approximately 15%.

Description

Technical Field

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

[0002] Carbon-carbon composite materials are made by a cracking reaction of carbon source gas inside a preform, which generates carbon and deposits it in the preform, and the density of the preform increases accordingly. The preparation cycle and mechanical properties of carbon-carbon composite materials are closely related to the density and structure of the preform. The density of existing carbon fiber preforms is generally low, and the proportion of carbon elements required to deposit to the same density is also high, resulting in a long deposition cycle and high costs such as gas, electricity, and labor. In addition, the current carbon fiber preforms are alternately layered with carbon cloth and mesh, and needle punching can only introduce a few fibers from the carbon cloth and mesh in the longitudinal perpendicular direction. The shear resistance of carbon fiber is poor, especially when subjected to interlayer shear loads, and it is prone to failure. Therefore, the interlayer mechanical properties of the finished carbon-carbon composite material after deposition are poor, and delamination is prone to occur. Summary of the Invention

[0003] 1. Technical problem to be solved by the invention

[0004] In response to the above technical problems, the present invention provides a carbon-carbon composite material preform and a preparation method thereof, which requires a short deposition cycle and has good shear resistance.

[0005] 2. Technical solution

[0006] To solve the above problems, the present invention provides a technical solution: a method for preparing a carbon-carbon composite preform, comprising the following steps:

[0007] (1) Adding chopped fibers and graphite powder to an organic resin, adding anhydrous ethanol and stirring evenly, adjusting the viscosity to 80-100 mPas, and preparing a carbon fiber mixed solution;

[0008] (2) selecting a type A carbon cloth and a type B carbon cloth whose carbon fiber textures are perpendicular to each other, applying the carbon fiber mixture prepared in step (1) on the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively, and then alternately laying the type A carbon cloth and the type B carbon cloth to a target thickness to obtain a preform;

[0009] (3) Immersing the preform again in a carbon fiber mixture at 60-80° C. to fully fill the pores of the preform with the carbon fiber mixture, and cooling to room temperature;

[0010] (4) needle-punching the cooled preform, wherein the needle-punching directions are inclined relative to the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively, to obtain a three-dimensional needle-punched preform;

[0011] (5) The three-dimensional needle-punched preform is placed in an oven for high-temperature curing, and a carbon-carbon composite material preform is obtained after cooling.

[0012] Optionally, the inclination angle between the needling direction in step (4) and the plane where the type A carbon cloth and the type B carbon cloth are located is 30 to 50 degrees, and the needling density is controlled at 46 to 56 needles / cm 2 .

[0013] Optionally, in step (1), the weight proportion of the chopped fibers is 20 to 30, the weight proportion of the graphite powder is 5 to 10, the weight proportion of the organic resin is 60 to 70, and the weight proportion of the anhydrous ethanol is 5 to 10.

[0014] Optionally, the organic resin is one or more of furan resin, urea-formaldehyde resin, phenol-formaldehyde resin, and epoxy resin.

[0015] Optionally, in step (5), the temperature of the oven is controlled to be 150-200° C., and the curing time is 2-5 hours.

[0016] Optionally, the length of the chopped fibers in step (1) is 1 to 5 mm.

[0017] The present invention also discloses a carbon-carbon composite material preform obtained by the above-mentioned carbon-carbon composite material preparation method, characterized in that the density of the carbon-carbon composite material is 0.6-0.8g / cm 3 .

[0018] 3. Beneficial effects

[0019] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0020] (1) The method for preparing a carbon-carbon composite preform proposed in the embodiment of the present application fills the pores of the preform with short-cut fibers, and the density of the obtained preform is increased. Compared with the traditional carbon fiber preform, the density is deposited to 1.6 g / cm 3 The carbon-carbon composite material preparation cycle can be shortened by approximately 50%. Oblique needling of the preform, including the chopped fiber filling, increases the number of fibers in the preform's longitudinal direction, converting fiber shearing into fiber tension. This significantly improves the preform's interlaminar shear performance, increasing the interlaminar shear strength of the deposited carbon-carbon composite material by approximately 15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of type A carbon cloth proposed in Examples 2 and 3 of the present invention.

[0022] Figure 2 Schematic diagram of the B-type carbon cloth proposed in Examples 2 and 3 of the present invention. DETAILED DESCRIPTION

[0023] In order to further understand the content of the present invention, the present invention is described in detail with reference to the accompanying drawings and embodiments.

[0024] The present application will be further described below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended solely to illustrate the relevant inventions and are not intended to limit the inventions. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the drawings. Terms such as "first" and "second" in the present application are provided for the convenience of describing the technical solutions of the present invention and do not have a specific limiting effect. They are general references and do not constitute a limitation on the technical solutions of the present invention. It should be noted that the embodiments and features therein in the present application may be combined with each other unless there is a conflict. In the description of the present invention, it should be noted that terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] The present invention discloses a method for preparing a carbon-carbon composite material preform, comprising the following steps:

[0026] (1) Adding short fibers and graphite powder with a length of 1 to 5 mm to an organic resin, adding anhydrous ethanol and stirring evenly, adjusting the viscosity to 80-100 mPas, and preparing a carbon fiber mixed liquid, wherein the weight proportion of the short fibers is 20 to 30, the weight proportion of the graphite powder is 5 to 10, the weight proportion of the organic resin is 60 to 70, and the weight proportion of the anhydrous ethanol is 5 to 10; the organic resin is one or more of furan resin, urea-formaldehyde resin, phenolic resin, and epoxy resin; the short fibers mainly form oblique fibers, the length of which is shorter than 1 mm, and cannot form effective interlayer connections; if the length is longer than 5 mm, the uniformity of the mixed liquid cannot be guaranteed, and it cannot be effectively filled into the interior of the preform, thereby reducing the interlayer performance. If the viscosity of the carbon fiber mixture is lower than 80mPas, the mixture has high fluidity and poor plasticity, and the mixture cannot be retained in the pores of the preform. If the viscosity is too high, exceeding 100mPas, the mixture has poor fluidity and cannot be mixed evenly, which is not conducive to the mixture entering the interior of the preform, and ultimately has an adverse effect on the uniformity and density of the preform.

[0027] (2) selecting a type A carbon cloth and a type B carbon cloth whose carbon fiber textures are perpendicular to each other, applying the carbon fiber mixture prepared in step (1) on the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively, and then alternately laying the type A carbon cloth and the type B carbon cloth to a target thickness to obtain a preform;

[0028] (3) The preform is immersed again in a carbon fiber mixture at 60-80°C, so that the pores of the preform are fully filled with the carbon fiber mixture, and then cooled to room temperature; the mixture is mainly composed of resin. After the plying is completed, the preform is immersed in the mixture as a whole, so a suitable temperature is required to keep the fluidity of the mixture within a reasonable range so that the mixture can fully stay in the pores inside the preform. Below 60°C, the fluidity of the mixture is strong and it cannot be impregnated from the outside. If the temperature is too high, exceeding 80, the resin will solidify when the temperature is too high, so it cannot be too high. However, the painting in step (2) is done at room temperature. Since the mixture is applied from the inside, it can be impregnated at room temperature, and the fluidity can be stronger. At the same time, if the temperature is too high, it will cause great damage to the painting equipment.

[0029] (4) Needle punching the cooled preform, wherein the needling direction is inclined to the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively, with an inclination angle of 30° to 50°, and the needling density is controlled at 46 to 56 needles / cm 2 , a three-dimensional needle punched preform is obtained; the tilt angle is maintained at 30-50°, mainly to control the angle of the oblique fibers and give full play to the mechanical reinforcement properties of the oblique fibers. An angle lower than 30° or higher than 50° will lead to a decrease in performance. When the needle punching density is lower than 46 needles / cm 2 , the interlayer fibers produced are less, which will lead to reduced interlayer performance; the needle density is higher than 56 needles / cm 2 , acupuncture causes serious damage to the fibers, resulting in a decrease in the overall mechanical properties of the product.

[0030] (5) The three-dimensional needle-punched preform is placed in an oven at 150-200°C for high-temperature curing for 2-5 hours, and then cooled to obtain a carbon-carbon composite material preform. If the temperature is lower than 150°C, the preform will have a lot of residual moisture and cannot be fully cured and shaped; if the temperature is higher than 200°C, the preform will fail due to high-temperature oxidation.

[0031] The carbon-carbon composite material prepared by the above preparation method has a density of 0.6-0.8g / cm 3 .

[0032] The carbon fiber textures of type A carbon cloth and type B carbon cloth are perpendicular to each other. The carbon fiber mixture is applied to type A carbon cloth and type B carbon cloth, and the preform is immersed in the carbon fiber mixture. The chopped fibers fill the pores of the preform, and the density of the preform is increased, and the deposition is up to 1.6g / cm 3The carbon-carbon composite material production cycle can be shortened by approximately 50%. Oblique needling of the preform, including the chopped fiber filling, increases the number of fibers in the preform's longitudinal direction, converting shear forces into tension forces. This significantly improves the preform's interlaminar shear performance, increasing the interlaminar shear strength of the deposited carbon-carbon composite material by approximately 15%. Graphite acts as a lubricant during the needling process, facilitating the formation of the obliquely needled carbon fibers.

[0033] Example 1

[0034] (1) Cutting continuous carbon fibers into 4 mm long chopped carbon fibers, adding the chopped fibers and graphite powder into an organic resin, adding a small amount of anhydrous ethanol to adjust the viscosity to 95 mPas, and uniformly stirring the mixture with an ultrasonic stirring device to prepare a carbon fiber mixture; the weight fraction of the chopped carbon fibers is 20, the weight fraction of the graphite powder is 5, the weight fraction of the phenolic resin is 60, and the weight fraction of the anhydrous ethanol is 8;

[0035] (2) Selecting a type A carbon cloth whose carbon fiber texture forms an angle of 45° with the horizontal direction, and selecting a type B carbon cloth whose carbon fiber texture forms an angle of -45° with the horizontal direction, respectively applying the carbon fiber mixture prepared in step (1) on the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, and then alternately laying the type A carbon cloth and the type B carbon cloth to the target thickness;

[0036] (3) Immerse the laid preform again in a carbon fiber mixture at 65°C, so that the pores and upper and lower surfaces of the preform are fully filled with the mixture, and then cool naturally;

[0037] (4) The cooled preform is needle-punched, and the needle-punching direction is inclined to the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively, with an inclination angle of 45°, and the needle-punching density is controlled at 48 needles / cm 2 , obtaining a three-dimensional needle-punched preform;

[0038] (5) The three-dimensional needle-punched preform was placed in an oven at 180°C for high-temperature curing for 2 hours. After cooling, the density was 0.66 g / cm 3 Carbon-carbon composite material preform.

[0039] Example 2

[0040] (1) Cutting continuous carbon fibers into chopped carbon fibers with a length of 2 mm, adding the chopped fibers and graphite powder into an organic resin, adding a small amount of anhydrous ethanol to adjust the viscosity to 90 mPas, and uniformly stirring the mixture with an ultrasonic stirring device to prepare a carbon fiber mixture; the weight fraction of the chopped carbon fibers is 25, the weight fraction of the graphite powder is 6, the weight fraction of the phenolic resin is 65, and the weight fraction of the anhydrous ethanol is 6;

[0041] (2) Selecting a type A carbon cloth whose carbon fiber texture forms an angle of 0° with the horizontal direction, and selecting a type B carbon cloth whose carbon fiber texture forms an angle of 90° with the horizontal direction, respectively applying the carbon fiber mixture prepared in step (1) on the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, and then alternately laying the type A carbon cloth and the type B carbon cloth to the target thickness;

[0042] (3) Immerse the laid preform again in a carbon fiber mixture at 70°C, so that the pores and upper and lower surfaces of the preform are fully filled with the mixture, and then cool naturally;

[0043] (4) The cooled preform is needle-punched. The needle-punching direction is inclined to the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively. The inclination angle is 45°, and the needle-punching density is controlled at 52 needles / cm 2 , obtaining a three-dimensional needle-punched preform;

[0044] (5) The three-dimensional needle-punched preform was placed in an oven at 180°C for high-temperature curing for 3 hours. After cooling, the density was 0.76 g / cm 3 Carbon-carbon composite material preform.

[0045] Example 3

[0046] (1) Cutting continuous carbon fibers into 1 mm long chopped carbon fibers, adding the chopped fibers and graphite powder into an organic resin, adding a small amount of anhydrous ethanol to adjust the viscosity to 85 mPas, and uniformly stirring the mixture with an ultrasonic stirring device to prepare a carbon fiber mixture; the weight fraction of the chopped carbon fibers is 28, the weight fraction of the graphite powder is 7, the weight fraction of the phenolic resin is 60, and the weight fraction of the anhydrous ethanol is 7;

[0047] (2) Selecting a type A carbon cloth whose carbon fiber texture forms an angle of 0° with the horizontal direction, and selecting a type B carbon cloth whose carbon fiber texture forms an angle of 90° with the horizontal direction, respectively applying the carbon fiber mixture prepared in step (1) on the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, and then alternately laying the type A carbon cloth and the type B carbon cloth to the target thickness;

[0048] (3) Immerse the laid preform again in the carbon fiber mixture at 75°C, so that the pores and upper and lower surfaces of the preform are fully filled with the mixture, and then cool naturally;

[0049] (4) The cooled preform is needle-punched. The needle-punching direction is inclined to the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively. The inclination angle is 45°, and the needle-punching density is controlled at 54 needles / cm 2 , obtaining a three-dimensional needle-punched preform;

[0050] (5) The three-dimensional needle-punched preform was placed in an oven at 195°C for high-temperature curing for 5 hours. After cooling, the density was 0.78 g / cm 3 Carbon-carbon composite material preform.

[0051] Comparative Example

[0052] The carbon fiber mesh and carbon cloth are alternately layered and fixed by vertical needle punching using a needle punching machine, wherein the carbon fiber mesh is prepared by a conventional preparation method.

[0053] The conventional carbon fiber preform and the carbon-carbon composite material preforms prepared in Examples 1 to 3 were subjected to a settling cycle test and an interlaminar shear strength test. The test data are shown in Table 1:

[0054]

[0055] Table 1

[0056] The test shows that the shorter the chopped carbon fiber is, the larger its weight proportion is, and the higher the needle-punching density is, the higher the density of the carbon-carbon composite preform is, the shorter the deposition cycle is, and the stronger the interlayer shear strength is.

[0057] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs a structure and embodiment similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon-carbon composite preform, characterized in that: The steps include: (1) Adding chopped fibers and graphite powder to an organic resin, adding anhydrous ethanol and stirring evenly, adjusting the viscosity to 80-100 mPas, and preparing a carbon fiber mixed solution; (2) selecting a type A carbon cloth and a type B carbon cloth whose carbon fiber textures are perpendicular to each other, applying the carbon fiber mixture prepared in step (1) on the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively, and then alternately laying the type A carbon cloth and the type B carbon cloth to a target thickness to obtain a preform; (3) Immersing the preform again in a carbon fiber mixture at 60-80° C. to fully fill the pores of the preform with the carbon fiber mixture, and cooling to room temperature; (4) needle-punching the cooled preform, wherein the needle-punching directions are inclined relative to the upper surface of the type A carbon cloth and the upper surface of the type B carbon cloth, respectively, to obtain a three-dimensional needle-punched preform; (5) placing the three-dimensional needle-punched preform in an oven for high-temperature curing, and obtaining a carbon-carbon composite material preform after cooling; The inclination angle between the needle punching direction in step (4) and the plane where the type A carbon cloth and the type B carbon cloth are located is 30-50°, and the needle punching density is controlled at 46-56 needles / cm 2 ; In step (5), the temperature of the oven is controlled to be 150-200° C., and the curing time is 2-5 hours; The length of the chopped fibers in step (1) is 1 to 5 mm.

2. The method for preparing a carbon-carbon composite preform according to claim 1, characterized in that: In the step (1), the weight proportion of the chopped fibers is 20 to 30, the weight proportion of the graphite powder is 5 to 10, the weight proportion of the organic resin is 60 to 70, and the weight proportion of the anhydrous ethanol is 5 to 10.

3. The method for preparing a carbon-carbon composite preform according to claim 1, wherein: The organic resin is one or more of furan resin, urea-formaldehyde resin, phenol-formaldehyde resin and epoxy resin.

4. A carbon-carbon composite material preform obtained by the method for preparing a carbon-carbon composite material according to any one of claims 1 to 3, characterized in that: The density of the carbon-carbon composite material is 0.6-0.8 g / cm 3 .

Images