High thermal conductive thin-walled unidirectional carbon / carbon composite material and preparation method thereof

Abstract

This invention discloses a high thermal conductivity thin-walled unidirectional carbon / carbon composite material and its preparation method. The method involves preparing a non-woven fabric from first mesophase pitch-based carbon fiber bundles after unwinding; weaving fiber bundles formed by unwinding second mesophase pitch-based carbon fiber bundles along the weft direction of the non-woven fabric to obtain a mesophase pitch-based carbon fiber cloth; pre-depositing pyrolytic carbon on the mesophase pitch-based carbon fiber cloth to obtain a pretreated mesophase pitch-based carbon fiber cloth; laying up the pretreated mesophase pitch-based carbon fiber cloth and pressing it along the thickness direction to obtain a unidirectional preform; densifying the unidirectional preform using a chemical vapor infiltration process, followed by graphitization heat treatment; and obtaining a high thermal conductivity thin-walled unidirectional carbon / carbon composite material after the graphitization heat treatment. This invention aims to optimize the structure of the unidirectional preform by weaving fiber bundles along the fiber radial direction to enhance the bonding strength between fiber bundles, avoid inter-bundle cracking, and ultimately achieve the fabrication of large-size thin-walled C / C composite material components.

Description

Technical Field

[0001] This invention belongs to the field of carbon / carbon composite material preparation technology, and relates to a high thermal conductivity thin-walled unidirectional carbon / carbon composite material and its preparation method. Background Technology

[0002] Carbon-based composites (C / C composites) with carbon fiber as reinforcement have become key materials for aerospace vehicles, launch vehicles, and exploration satellites due to their low density, high specific strength, high modulus, and good high-temperature mechanical properties. C / C composites can be classified into unidirectional (1D), two-dimensional (2D), two-dimensional needled (2.5D), and three-dimensional (3D) composites according to the type of preform. Among them, unidirectional C / C composites have high anisotropy and an axial tensile strength of up to 690 MPa (Li Hejun, Fu Qiangang, et al.; Carbon / Carbon Composites [M]. China Railway Publishing House, 2017); and mesophase pitch-based carbon fiber (CF2C / C4) composites... MP The unidirectional C / C composite material prepared by this method can achieve a thermal conductivity of 734 W·m along the fiber axis. -1 ·K -1 (JFLin,GMYuan,XKLi,etal.,Preparation of 1D C / C composites with high thermal conductivity[J].Journal of Inorganic Materials,2013,28(12):1338-1344), with excellent performance, therefore, according to the structural application requirements, the composite material structural parts can be optimized through layup design to achieve zonal control of performance. With the further development of aerospace, lightweight design has become an important means to improve equipment performance and reduce energy consumption. The preparation of large-size, thin, light, strong and highly thermally conductive unidirectional C / C composite materials shows great application prospects. Although unidirectional C / C composite materials have excellent tensile strength along the axial direction, the bonding force between fiber bundles along the radial direction is poor. For large-size thin-walled samples, cracking is easily caused by large thermal stress during the preparation process, and the load-bearing function cannot be fully utilized. Therefore, structural design of unidirectional high thermal conductivity C / C composite materials to reduce radial cracking and realize the preparation of large-size, thin-walled unidirectional C / C composite materials is an urgent problem to be solved. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, the present invention aims to provide a high thermal conductivity thin-walled unidirectional carbon / carbon composite material and its preparation method. The present invention aims to optimize the structure of the unidirectional preform by weaving fiber bundles along the fiber radial direction to enhance the bonding strength between fiber bundles, avoid inter-bundle cracking, and ultimately realize the preparation of large-size thin-walled C / C composite material components.

[0004] The technical solution adopted in this invention is as follows:

[0005] A method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material, comprising:

[0006] Nonwoven fabric was prepared by spreading the first mesophase pitch-based carbon fiber bundles.

[0007] A fiber bundle composed of second mesophase pitch-based carbon fiber bundles is woven along the weft direction of the non-weft fabric to obtain a mesophase pitch-based carbon fiber fabric with fiber bundles in both the warp and weft directions.

[0008] Pyrolytic carbon was pre-deposited onto the mesophase pitch-based carbon fiber cloth to obtain a pretreated mesophase pitch-based carbon fiber cloth.

[0009] The pretreated mesophase pitch-based carbon fiber cloth is laid up and pressed along the thickness direction to obtain a unidirectional preform.

[0010] The unidirectional preform is densified using a chemical vapor infiltration process, followed by graphitization heat treatment. After the graphitization heat treatment is completed, the high thermal conductivity thin-walled unidirectional carbon / carbon composite material is obtained.

[0011] Preferably, the first mesophase pitch-based carbon fiber bundle is a 2k mesophase pitch-based carbon fiber bundle.

[0012] Preferably, the second mesophase pitch-based carbon fiber bundle is a 1k mesophase pitch-based carbon fiber bundle.

[0013] Preferably, the width of the second mesophase pitch-based carbon fiber bundle after spreading is 3-4 mm.

[0014] Preferably, the thickness of the mesophase pitch-based carbon fiber cloth is 0.15-0.20 mm and the warp-to-weft ratio is 4:1.

[0015] Preferably, when pre-depositing pyrolytic carbon onto the mesophase pitch-based carbon fiber cloth, the deposition temperature is 1000-1100℃, the pressure is 2-5kPa, the natural gas flow rate is 15-18L / min, and the deposition time is 30-50min.

[0016] Preferably, when the pretreated mesophase pitch-based carbon fiber cloth is laid up and pressed along the thickness direction, the number of layers of the pretreated mesophase pitch-based carbon fiber cloth is 4-6, and the clamping force for pressing along the thickness direction is 50-60 kPa.

[0017] Preferably, when the unidirectional preform is densified using a chemical vapor infiltration process, the infiltration temperature is 1000-1100℃, the pressure is 8-15kPa, the natural gas flow rate is 15-18L / min, and the deposition time is 150-180h.

[0018] The temperature for graphitization heat treatment is 2500-2600℃ and the time is 90-120min.

[0019] The present invention also provides a high thermal conductivity thin-walled unidirectional carbon / carbon composite material, which is prepared by the preparation method described above.

[0020] Preferably, the density of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material is 1.85-1.88 g / cm³. 3 The thickness is 0.7-1.0 mm;

[0021] The thermal conductivity of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material along the warp of the fiber cloth is 700-730 W·m. -1 ·K -1 The thermal conductivity along the weft direction of the fiber fabric is 80-90 W·m. -1 ·K -1 ;

[0022] The high thermal conductivity thin-walled unidirectional carbon / carbon composite material has a tensile strength of 600-700 MPa along the warp direction of the fiber cloth and a tensile strength of 18-23 MPa along the weft direction of the fiber cloth.

[0023] The present invention has the following beneficial effects:

[0024] This invention incorporates fiber bundles formed by the spreading of second mesophase pitch-based carbon fiber bundles into the weft direction of a non-woven fabric. These fiber bundles act as connectors, strengthening the radial bonding strength between fiber bundles and preventing inter-bundle cracking, which is beneficial for the fabrication of large-size thin-walled C / C composite components. The pre-deposition of pyrolytic carbon on the mesophase pitch-based carbon fiber fabric primarily serves a pre-densification function. High-texture pyrolytic carbon is pre-deposited at locations that are difficult to deposit, such as within and between fiber bundles, and at the intersections of warp and weft fiber bundles. This prevents excessive porosity caused by ineffective deposition at these locations during the subsequent overall densification process, which would negatively impact the overall mechanical properties of the composite material. Attached Figure Description

[0025] Figure 1(a) is a schematic diagram of the weaving method of unidirectional mesophase pitch-based carbon fiber cloth in an embodiment of the present invention; Figure 1(b) is a macroscopic photograph of the mesophase pitch-based carbon fiber cloth in an embodiment of the present invention.

[0026] Figure 2(a) is a macroscopic photograph of a fiber cloth made of 1k mesophase pitch-based carbon fiber bundles; Figure 2(b) is a macroscopic photograph of a fiber cloth made of 2k mesophase pitch-based carbon fiber bundles.

[0027] Figure 3 The images show a comparison of the crack resistance of the prepared large-size, unidirectional thin-walled C / C composite material, where (a) is a conventional unidirectional C / C composite material and (b) is the high thermal conductivity thin-walled unidirectional carbon / carbon composite material of the present invention.

[0028] Figure 4 This is a macroscopic photograph of the unidirectional C / C composite material prepared in Example 2 of the present invention;

[0029] Figure 5(a) is a schematic diagram of the weaving method of unidirectional mesophase pitch-based carbon fiber cloth in Comparative Example 2 of the present invention, and Figure 5(b) is a photograph of the C / C composite material obtained in Comparative Example 2 of the present invention.

[0030] In the figure, 1 represents 2k mesophase pitch-based carbon fiber, and 2 represents 1k mesophase pitch-based carbon fiber. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] This invention optimizes the preform structure by weaving a small number of fiber bundles along the radial direction of the fiber in a unidirectional fiber cloth to enhance the inter-bundle bonding, and then uses a chemical vapor infiltration process to prepare large-size, high thermal conductivity thin-walled C / C composite materials.

[0033] Specifically, the preparation method of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material of the present invention includes the following steps:

[0034] Step 1: Preparation of unidirectional mesophase pitch-based carbon fiber cloth: After being unfurled, 2k mesophase pitch-based carbon fiber bundles are arranged and woven along the radial direction of the fibers to prepare a non-woven cloth. At the same time, 1k mesophase pitch-based carbon fiber bundles are unfurled into 3-4mm wide fiber bundles (weft direction) along the weft direction of the non-woven cloth, with a warp-to-weft ratio of 4:1. This results in the preparation of a mesophase pitch-based carbon fiber cloth with fiber bundles in both the warp and weft directions (as shown in Figure 1(a) and Figure 1(b)). The thickness of the obtained fiber cloth is 0.15-0.20mm, and the width of the fiber cloth along the weft direction is limited to 16-20cm.

[0035] Step 2: Fiber Cloth Pretreatment: The prepared mesophase pitch-based carbon fiber cloth is pre-deposited with pyrolytic carbon using a low-pressure chemical vapor infiltration (LPI) process to obtain the pre-treated fiber cloth. During the LPI pre-deposition of pyrolytic carbon, the deposition temperature is 1000-1100℃, the pressure is 2-5 kPa, the natural gas flow rate is 15-18 L / min, and the deposition time is 30-50 min.

[0036] Step 3: Preparation of unidirectional preform: The pretreated fiber cloth obtained in Step 2 is laid up, and then clamped along the thickness direction using a perforated graphite clamp. The perforated graphite clamp is then tightened with bolts to obtain the preform. The number of layers is 4-6, and the clamping force of the perforated graphite clamp is 50-60 kPa.

[0037] Step 4: Preparation of unidirectional high thermal conductivity C / C composite material: The preform obtained in Step 3 is densified using a chemical vapor infiltration (CVI) process. Specifically, the CVI process is carried out at a temperature of 1000-1100℃, a pressure of 8-15 kPa, a natural gas flow rate of 15-18 L / min, and a deposition time of 150-180 h. After the CVI process, a graphitization heat treatment is performed at 2500-2600℃ for 90-120 min. After the graphitization heat treatment, the high thermal conductivity thin-walled unidirectional carbon / carbon composite material of this invention is obtained.

[0038] The specific characteristics of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material of this invention are as follows: density is 1.85-1.88 g / cm³. 3 The thickness is 0.7-1.0mm and the width is 16-20cm.

[0039] In the above-mentioned scheme of the present invention, a small amount of mesophase pitch-based carbon fiber bundles with a width of 3-4 mm, formed by spreading 1k carbon fiber bundles, are woven into the weft direction of the non-woven fabric. The main functions are as follows: First, it serves as a connector to strengthen the bonding strength between fiber bundles along the radial direction; second, by limiting the width of the fiber bundles, the connector can fully fit the fiber bundles in the non-woven fabric, avoiding excessive width that causes excessive undulation of the non-woven fabric itself (Figure 5(a)), which easily generates large thermal stress during the deposition process, causing the fiber bundles to delaminate and crack at the intersection, thus reducing the bonding strength between the non-woven fabric layers; third, by limiting the type of fiber bundle, when using 2k fiber bundles with a spreading width of 3-4 mm, the thickness of the fiber bundles after spreading is large and the arrangement is tight, with fewer pores, which is not conducive to the deposition of pyrolytic carbon; while after spreading 1k fiber bundles, pore structures can still be observed between the fiber bundles, which is conducive to the deposition of pyrolytic carbon, as shown in Figure 2(a) and Figure 2(b).

[0040] The prepared fiber cloth is pretreated with low-pressure infiltration pyrolytic carbon, which mainly serves as a pre-densification process. High-texture pyrolytic carbon is pre-deposited in locations that are difficult to deposit, such as within and between fiber bundles and at the intersection of warp and weft fiber bundles. This prevents the formation of excessive pore structures in these locations during the subsequent overall densification process of the preform, which would affect the overall mechanical properties of the composite material.

[0041] Because large-sized, unidirectional thin-walled C / C composites have low bond strength along the fiber radial direction, they are prone to cracking during deposition due to thermal stress (e.g. Figure 3 In Figure (a), the composite material exhibits a state of imminent fracture; weaving a small number of narrow-width fibers radially into it can effectively increase the bonding strength between fiber bundles, enabling the fabrication of large-sized components (such as...). Figure 3 (Figure (b) in the text) simultaneously increases the radial load-bearing capacity of the composite material. The prepared large-size, unidirectional, thin-walled, high thermal conductivity C / C composite material is shown in Figure (b). Figure 3 Figure (b) in the middle and Figure 4 As shown, the density is 1.85-1.88 g / cm³. 3 The thickness is 0.7-1.0 mm, and the width is 16-20 cm. The thermal conductivity of the composite material along the warp of the fiber cloth is 700-730 W·m. -1 ·K -1 The fiber fabric has a weft length of 80-90 W·m. -1 ·K -1 The tensile strength of the composite material along the warp of the fiber cloth is 600-700 MPa, and along the weft of the fiber cloth is 18-23 MPa.

[0042] Example 1:

[0043] The preparation method of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material in this embodiment includes the following steps:

[0044] Step 1: Arrange the 2k mesophase pitch-based carbon fiber bundles after they have been unfurled along the radial direction of the fibers to prepare a non-woven fabric. At the same time, weave the 1k mesophase pitch-based carbon fiber bundles into 3mm wide fiber bundles (weft direction) along the weft direction of the non-woven fabric (as shown in Figure 2(a)). The warp-to-weft ratio is 4:1, thereby preparing the mesophase pitch-based carbon fiber fabric (as shown in Figure 1(b)). The thickness of the fiber fabric is 0.15mm, and the width of the fiber fabric along the weft direction is limited to 16cm.

[0045] Step 2: The prepared mesophase pitch-based carbon fiber cloth is deposited with pyrolytic carbon using a low-pressure chemical vapor infiltration process. The deposition temperature is 1000℃, the pressure is 2kPa, the natural gas flow rate is 15L / min, and the deposition time is 30min.

[0046] Step 3: Lay out the pretreated fiber cloth in layers, then clamp it using a custom-made perforated graphite clamp and secure it with bolts. The number of layers is 4, and the clamping force is 55 kPa.

[0047] Step 4: The preform is densified using chemical vapor infiltration (CVI) at a temperature of 1000℃, a pressure of 8 kPa, a natural gas flow rate of 15 L / min, and a deposition time of 150 h. Finally, it undergoes heat treatment at 2500℃ for 90 min. The resulting unidirectional composite material has a thickness of 0.7 mm, a width of 16 cm, and a density of 1.85 g / cm³. 3 The thermal conductivity along the warp direction of the fiber cloth is 700 W·m. -1 K -1 The latitudinal value is 80 W·m -1 K -1 The tensile strength of the composite material is 620 MPa in the warp direction and 18 MPa in the weft direction.

[0048] Example 2:

[0049] The preparation method of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material in this embodiment includes the following steps:

[0050] Step 1: Arrange the 2k mesophase pitch-based carbon fiber bundles after they have been unfurled along the radial direction of the fibers to prepare a non-woven fabric. At the same time, weave the 1k mesophase pitch-based carbon fiber bundles into 4mm wide fiber bundles (weft direction) along the weft direction of the non-woven fabric. The warp-to-weft ratio is 4:1, thereby preparing the mesophase pitch-based carbon fiber fabric. The thickness of the fiber fabric is 0.17mm, and the width of the fiber fabric along the weft direction is limited to 17cm.

[0051] Step 2: The prepared mesophase pitch-based carbon fiber cloth is deposited with pyrolytic carbon using a low-pressure chemical vapor infiltration process. The deposition temperature is 1050℃, the pressure is 4kPa, the natural gas flow rate is 16L / min, and the deposition time is 40min.

[0052] Step 3: Lay out the pretreated fiber cloth in layers, then clamp it using a custom-made perforated graphite clamp and secure it with bolts. The number of layers is 5, and the clamping force is 60 kPa.

[0053] Step 4: The preform is densified using chemical vapor infiltration (CVI) at a temperature of 1050℃, a pressure of 10 kPa, a natural gas flow rate of 16 L / min, and a deposition time of 160 h. Finally, it undergoes heat treatment at 2550℃ for 100 min. The resulting unidirectional composite material has a thickness of 0.9 mm (e.g., ...). Figure 4 It has a width of 17cm and a density of 1.86g / cm³. 3 The thermal conductivity of the composite material along the warp direction of the fiber cloth is 730 W·m. -1 K -1 The latitudinal value is 90 W·m -1 K -1The tensile strength of the composite material is 700 MPa in the warp direction and 23 MPa in the weft direction.

[0054] Example 3:

[0055] The preparation method of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material in this embodiment includes the following steps:

[0056] Step 1: Arrange the 2k mesophase pitch-based carbon fiber bundles, after being unfurled, along the radial direction of the fibers to prepare a non-woven fabric. Simultaneously, weave 3.5mm wide fiber bundles (weft direction) from 1k mesophase pitch-based carbon fiber bundles along the weft direction of the non-woven fabric, with a warp-to-weft ratio of 4:1, thereby preparing the mesophase pitch-based carbon fiber fabric. The thickness of the fiber fabric is 0.2mm, and the width of the fiber fabric along the weft direction is limited to 20cm.

[0057] Step 2: The prepared mesophase pitch-based carbon fiber cloth is deposited with pyrolytic carbon using a low-pressure chemical vapor infiltration process. The deposition temperature is 1100℃, the pressure is 5kPa, the natural gas flow rate is 18L / min, and the deposition time is 50min.

[0058] Step 3: Lay out the pretreated fiber cloth in layers, then clamp it using a custom-made perforated graphite clamp and secure it with bolts. The number of layers is 4, and the clamping force is 50 kPa.

[0059] Step 4: The preform is densified using chemical vapor infiltration (CVI) at a temperature of 1150℃, a pressure of 15 kPa, a natural gas flow rate of 18 L / min, and a deposition time of 180 h. Finally, it undergoes heat treatment at 2600℃ for 120 min. The resulting unidirectional composite material has a thickness of 0.9 mm, a width of 20 cm, and a density of 1.88 g / cm³. 3 The thermal conductivity along the warp direction of the fiber cloth is 720 W·m. -1 K -1 The latitudinal value is 85 W·m. -1 K -1 The tensile strength of the composite material is 650 MPa in the warp direction and 20 MPa in the weft direction.

[0060] Example 4

[0061] The preparation method of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material in this embodiment includes the following steps:

[0062] Step 1: Arrange the 2k mesophase pitch-based carbon fiber bundles, after being unfurled, along the radial direction of the fibers to prepare a non-woven fabric. Simultaneously, weave 3mm wide fiber bundles (weft direction) from 1k mesophase pitch-based carbon fiber bundles along the weft direction of the non-woven fabric, with a warp-to-weft ratio of 4:1, thereby preparing the mesophase pitch-based carbon fiber fabric. The thickness of the fiber fabric is 0.15mm, and the width of the fiber fabric along the weft direction is limited to 18cm.

[0063] Step 2: The prepared mesophase pitch-based carbon fiber cloth is deposited with pyrolytic carbon using a low-pressure chemical vapor infiltration process. The deposition temperature is 1000℃, the pressure is 2kPa, the natural gas flow rate is 15L / min, and the deposition time is 30min.

[0064] Step 3: Lay out the pretreated fiber cloth in layers, then clamp it using a custom-made perforated graphite clamp and secure it with bolts. The number of layers is 6, and the clamping force is 55 kPa.

[0065] Step 4: The preform is densified using chemical vapor infiltration (CVI) at a temperature of 1000℃, a pressure of 8 kPa, a natural gas flow rate of 15 L / min, and a deposition time of 150 h. Finally, it undergoes heat treatment at 2500℃ for 90 min. The resulting unidirectional composite material has a thickness of 1.0 mm, a width of 18 cm, and a density of 1.85 g / cm³. 3 (like Figure 3 (Figure (b)); The thermal conductivity along the warp of the fiber fabric is 720 W·m. -1 K -1 The latitudinal value is 82 W·m. -1 K -1 The tensile strength of the composite material is 630 MPa in the warp direction and 19 MPa in the weft direction.

[0066] Comparative Example 1:

[0067] The preparation method of this comparative unidirectional composite material includes the following steps:

[0068] Step 1: Arrange the 2k fiber bundles after spreading along the radial direction of the fibers to weave a non-woven fabric. The thickness of the non-woven fabric is 0.15mm, and the width of the fiber fabric along the weft direction is 18cm.

[0069] Step 2: The prepared mesophase pitch-based carbon fiber cloth is deposited with pyrolytic carbon using a low-pressure chemical vapor infiltration process. The deposition temperature is 1000℃, the pressure is 2kPa, the natural gas flow rate is 15L / min, and the deposition time is 30min.

[0070] Step 3: Lay out the pretreated fiber cloth in layers, then clamp it using a custom-made perforated graphite clamp and secure it with bolts. The number of layers is 6, and the clamping force is 55 kPa.

[0071] Step 4: The preform is densified using chemical vapor infiltration (CVI) at a temperature of 1000℃, a pressure of 8 kPa, a natural gas flow rate of 15 L / min, and a deposition time of 150 h. Finally, it undergoes heat treatment at 2500℃ for 90 min. The resulting unidirectional composite material has a thickness of 1.0 mm, a width of 18 cm, and a density of 1.85 g / cm³. 3 The thermal conductivity along the warp direction of the fiber cloth is 630 W·m. -1 K -1 The latitudinal value is 60 W·m -1 K -1 The tensile strength of the composite material is 650 MPa in the warp direction and 3 MPa in the weft direction.

[0072] Compared to Example 4, the comparative example used only non-woven fabric to prepare large-sized unidirectional composite materials, resulting in lower bonding strength between fiber bundles. This led to cracking during deposition due to higher thermal stress. Figure 3 As shown in Figure (a), the composite material exhibits a bending deformation along the fiber radial direction when held in the hand, and cannot maintain the structural stability of the material itself.

[0073] Comparative Example 2:

[0074] The preparation method of this comparative unidirectional composite material includes the following steps:

[0075] Step 1: Arrange the 2k mesophase pitch-based carbon fiber bundles, after being unfurled, along the radial direction of the fibers to prepare a non-woven fabric. Simultaneously, weave a 6mm wide fiber bundle (weft direction) made from 1k mesophase pitch-based carbon fiber bundles along the weft direction of the non-woven fabric, with a warp-to-weft ratio of 4:1. This yields a mesophase pitch-based carbon fiber fabric with a thickness of 0.17mm and a weft width of 17cm.

[0076] Step 2: The prepared mesophase pitch-based carbon fiber cloth is deposited with pyrolytic carbon using a low-pressure chemical vapor infiltration process. The deposition temperature is 1050℃, the pressure is 4kPa, the natural gas flow rate is 16L / min, and the deposition time is 40min.

[0077] Step 3: Lay out the pretreated fiber cloth in layers, then clamp it using a custom-made perforated graphite clamp and secure it with bolts. The number of layers is 5, and the clamping force is 60 kPa.

[0078] Step 4: The preform is densified using chemical vapor infiltration (CVI) at a temperature of 1050℃, a pressure of 10 kPa, a natural gas flow rate of 16 L / min, and a deposition time of 160 h. Finally, it undergoes heat treatment at 2550℃ for 100 min. The resulting unidirectional composite material has a thickness of 0.9 mm, a width of 17 cm, and a density of 1.83 g / cm³. 3 The thermal conductivity along the warp direction of the fiber cloth is 700 W·m. -1 K -1 The latitudinal value is 60 W·m -1 K -1 The tensile strength of the composite material is 680 MPa in the warp direction and 8 MPa in the weft direction.

[0079] Compared with Example 2, the comparative example used mesophase pitch-based carbon fiber with a width of 6 mm as the connector. Due to the excessive width, the fiber bundles did not fit tightly at the intersection, and the non-woven fabric itself had excessive undulations (as shown in Figure 5(a)), resulting in poor flatness. This led to interlayer delamination and cracking during the deposition process, as shown in Figure 5(b).

Claims

1. A method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material, characterized in that, include: Nonwoven fabric was prepared by spreading the first mesophase pitch-based carbon fiber bundles. A fiber bundle composed of second mesophase pitch-based carbon fiber bundles is woven along the weft direction of the non-weft fabric to obtain a mesophase pitch-based carbon fiber fabric with fiber bundles in both the warp and weft directions; wherein, the width of the second mesophase pitch-based carbon fiber bundle after being woven is 3-4 mm. Pyrolytic carbon was pre-deposited onto the mesophase pitch-based carbon fiber cloth to obtain a pretreated mesophase pitch-based carbon fiber cloth. The pretreated mesophase pitch-based carbon fiber cloth is laid up and pressed along the thickness direction to obtain a unidirectional preform. The unidirectional preform is densified using a chemical vapor infiltration process, followed by graphitization heat treatment. After the graphitization heat treatment is completed, the high thermal conductivity thin-walled unidirectional carbon / carbon composite material is obtained.

2. The method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material according to claim 1, characterized in that, The first mesophase pitch-based carbon fiber bundle uses a 2 k mesophase pitch-based carbon fiber bundle.

3. The method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material according to claim 1, characterized in that, The second mesophase pitch-based carbon fiber bundle uses a 1 k mesophase pitch-based carbon fiber bundle.

4. The method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material according to claim 1, characterized in that, The thickness of the mesophase pitch-based carbon fiber cloth is 0.15-0.20 mm, and the warp-to-weft ratio is 4:

1.

5. The method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material according to claim 1, characterized in that, When pre-depositing pyrolytic carbon onto the mesophase pitch-based carbon fiber cloth, the deposition temperature is 1000-1100 ℃, the pressure is 2-5 kPa, the natural gas flow rate is 15-18 L / min, and the deposition time is 30-50 min.

6. The method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material according to claim 1, characterized in that, When the pretreated mesophase pitch-based carbon fiber cloth is laid up and pressed along the thickness direction, the number of layers of the pretreated mesophase pitch-based carbon fiber cloth is 4-6, and the clamping force along the thickness direction is 50-60 kPa.

7. The method for preparing a high thermal conductivity thin-walled unidirectional carbon / carbon composite material according to claim 1, characterized in that, When the unidirectional preform is densified using a chemical vapor infiltration process, the infiltration temperature is 1000-1100 ℃, the pressure is 8-15 kPa, the natural gas flow rate is 15-18 L / min, and the deposition time is 150-180 h. The temperature for graphitization heat treatment is 2500-2600 ℃ and the time is 90-120 min.

8. A high thermal conductivity thin-walled unidirectional carbon / carbon composite material, characterized in that, The high thermal conductivity thin-walled unidirectional carbon / carbon composite material is prepared by the preparation method described in any one of claims 1-7.

9. A high thermal conductivity thin-walled unidirectional carbon / carbon composite material according to claim 8, characterized in that, The density of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material is 1.85-1.88 g / cm³. 3 The thickness is 0.7-1.0 mm; The thermal conductivity of the high thermal conductivity thin-walled unidirectional carbon / carbon composite material along the warp of the fiber cloth is 700-730 W·m. -1 ·K -1 The thermal conductivity along the weft direction of the fiber fabric is 80-90 W·m. -1 ·K -1 ; The high thermal conductivity thin-walled unidirectional carbon / carbon composite material has a tensile strength of 600-700 MPa along the warp direction of the fiber cloth and a tensile strength of 18-23 MPa along the weft direction of the fiber cloth.

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