Carbon fiber preform, carbon fiber material and preparation method and application thereof

Abstract

The invention provides a carbon fiber preform, a carbon fiber material and a preparation method and application thereof. The carbon fiber preform comprises at least two first carbon fiber layers and at least one second carbon fiber layer which are stacked; at least one second carbon fiber layer is arranged between the adjacent first carbon fiber layers; the second carbon fiber layer comprises a plurality of carbon fiber sheets; in the second carbon fiber layer, the ratio of the number of the carbon fiber sheets forming an included angle of greater than or equal to 30 degrees with the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%; the transverse size of the first carbon fiber layer is greater than 50mm; and the transverse size of the carbon fiber sheet is 2.5 mm to 30 mm. The carbon fiber preform has high structural stability, is beneficial to preparation of a carbon fiber material with excellent mechanical properties, and is beneficial to wide application of the carbon fiber material.

Description

Technical Field

[0001] The present application relates to the field of carbon fiber materials, and particularly to carbon fiber preforms, carbon fiber materials, and their preparation methods and applications. Background Art

[0002] At present, carbon fiber materials have attracted much attention due to their low density, high temperature resistance, friction resistance, and excellent mechanical properties. The carbon fiber preform is the core framework of the carbon fiber material and determines the final performance of the material. The related technology mainly prepares the carbon fiber preform by needling after laminating multiple carbon fiber layers. This process has a long process time, high cost, large loss, and poor needling stability, which affects the performance and service life of the carbon fiber material and is not conducive to the wide use of the carbon fiber material. Therefore, it is necessary to further research and develop the carbon fiber preform and the carbon fiber material. Summary of the Invention

[0003] In view of this, the present application provides a carbon fiber preform, a carbon fiber material, and their preparation methods and applications. The carbon fiber preform and the carbon fiber material have a special lamination method, which increases the internal stability and bonding performance of the carbon fiber preform, improves the bending strength and shear strength of the carbon fiber material, and is conducive to the application of the carbon fiber material.

[0004] In a first aspect, the present application provides a carbon fiber preform, which includes at least two first carbon fiber layers and at least one second carbon fiber layer arranged in a laminated manner; at least one second carbon fiber layer is provided between adjacent first carbon fiber layers; the second carbon fiber layer includes a plurality of carbon fiber sheets; in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%; the transverse dimension of the first carbon fiber layer is greater than 50 mm; the transverse dimension of the carbon fiber sheet is 2.5 mm - 30 mm.

[0005] Optionally, the angles between the plurality of carbon fiber sheets and the first carbon fiber layer are all 45° - 90°.

[0006] Optionally, the length of the carbon fiber sheet is 2.5 mm - 30 mm, the width is 2.5 mm - 18 mm, and the thickness is 1 mm - 3 mm.

[0007] Optionally, the thickness of the carbon fiber preform is 2.5 mm - 200 mm.

[0008] The carbon fiber preform provided by the present application does not use the needling method for consolidation between carbon fiber layers, but enhances the bonding performance between layers inside the carbon fiber preform by overlapping the carbon fiber sheets in the second carbon fiber layer with adjacent first carbon fiber layers, which is conducive to obtaining a carbon fiber material with excellent mechanical properties.

[0009] Second aspect, the present application provides a method for preparing a carbon fiber preform, including:

[0010] Stack at least two first carbon fiber layers and at least one second carbon fiber layer, and provide at least one second carbon fiber layer between adjacent first carbon fiber layers to obtain a carbon fiber preform, wherein the second carbon fiber layer includes a plurality of carbon fiber sheets. In the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%. The lateral dimension of the first carbon fiber layer is greater than 50 mm, and the lateral dimension of the carbon fiber sheet is 2.5 mm - 30 mm.

[0011] The method for preparing the carbon fiber preform provided by the present application is novel, the preparation process is simple, and the performance of the prepared product is excellent.

[0012] Third aspect, the present application provides a carbon fiber material, including at least two first carbon fiber layers, at least one second carbon fiber layer and a carbon material; the first carbon fiber layer and the second carbon fiber layer are stacked; at least one second carbon fiber layer is provided between adjacent first carbon fiber layers; the second carbon fiber layer includes a plurality of carbon fiber sheets; in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%; the lateral dimension of the first carbon fiber layer is greater than 50 mm; the lateral dimension of the carbon fiber sheet is 2.5 mm - 30 mm.

[0013] Optionally, the carbon material further includes silicon element.

[0014] Optionally, the flexural strength of the carbon fiber material is 100 MPa - 200 MPa.

[0015] Optionally, the shear strength of the carbon fiber material is 10.6 MPa - 20 MPa.

[0016] Optionally, the mass wear rate of the carbon fiber material after wearing for 120 min at 1000 r / min is less than or equal to 6‰.

[0017] In the carbon fiber material provided by the present application, the carbon fiber sheets in the second carbon fiber layer lap adjacent first carbon fiber layers, improving the bonding performance between layers, thereby improving the mechanical properties of the carbon fiber material, such as flexural strength, shear strength, etc., which is beneficial to enhancing the product competitiveness of the carbon fiber material.

[0018] Fourth aspect, the present application provides a method for preparing a carbon fiber material, including:

[0019] At least two first carbon fiber layers and at least one second carbon fiber layer are stacked, and at least one second carbon fiber layer is provided between adjacent first carbon fiber layers to obtain a carbon fiber preform, wherein the second carbon fiber layer comprises a plurality of carbon fiber sheets, and in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%, the lateral dimension of the first carbon fiber layer is greater than 50 mm, and the lateral dimension of the carbon fiber sheet is 2.5 mm - 30 mm;

[0020] The carbon fiber preform is deposited with carbon, impregnated with resin, and then obtained as a carbon fiber material after curing and carbonization treatment.

[0021] Optionally, after the carbonization treatment, a graphitization treatment is further included, the temperature of the graphitization treatment is 1800°C - 3000°C, and the time is 1 h - 10 h.

[0022] Optionally, after the graphitization treatment, a ceramization treatment is further included, the temperature of the ceramization treatment is 1400°C - 2400°C, and the time is 0.5 h - 10 h.

[0023] The method for preparing the carbon fiber material provided by the present application is simple, convenient to operate, and has high production efficiency, can realize large-scale production of the carbon fiber material, and is beneficial to the use of the carbon fiber material.

[0024] In a fifth aspect, the present application provides a structural member, and the material of the structural member includes the carbon fiber material described in the third aspect or the carbon fiber material prepared by the preparation method described in the fourth aspect.

[0025] Optionally, the structural member includes a brake disc.

[0026] The structural member provided by the present application is made of carbon fiber material, has low density, light weight, good bending strength and shear strength, and long service life, which is beneficial to the use of the structural member.

[0027] In a sixth aspect, the present application provides a braking system, and the braking system includes the structural member described in the fifth aspect.

[0028] The braking system provided by the present application has excellent braking effect and good mechanical properties, which is beneficial to the wide use of the braking system.

[0029] In a seventh aspect, the present application provides a vehicle, and the vehicle includes the braking system described in the sixth aspect.

[0030] The vehicle provided by the present application has excellent comprehensive performance, greatly improved safety performance, and strong product competitiveness. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Figure 1 Schematic cross-sectional view of a carbon fiber preform provided by an embodiment of the present application.

[0033] Figure 2 Schematic structural view of a carbon fiber sheet and a first carbon fiber layer provided by an embodiment of the present application.

[0034] Figure 3 Schematic cross-sectional view of a carbon fiber preform provided by another embodiment of the present application.

[0035] Figure 4 Flowchart of a preparation method of a carbon fiber material provided by an embodiment of the present application. Detailed implementation manners

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0037] Please refer to Figure 1 and Figure 2 , Figure 1 Schematic cross-sectional view of a carbon fiber preform provided by an embodiment of the present application, Figure 2 Schematic structural view of a carbon fiber sheet and a first carbon fiber layer provided by an embodiment of the present application. The carbon fiber preform 100 includes at least two first carbon fiber layers 10 and at least one second carbon fiber layer 20; at least one second carbon fiber layer 20 is provided between adjacent first carbon fiber layers 10; the second carbon fiber layer 20 includes a plurality of carbon fiber sheets 21; in the second carbon fiber layer 20, the ratio of the number of carbon fiber sheets 21 with an angle greater than or equal to 30° to the first carbon fiber layer 10 to the number of the plurality of carbon fiber sheets 21 is greater than or equal to 30%, the lateral dimension of the first carbon fiber layer 10 is greater than 50 mm, and the lateral dimension of the carbon fiber sheet 21 is 2.5 mm - 30 mm.

[0038] The carbon fiber preform provided by this application has a novel structure. The inclined arrangement of the carbon fiber sheets in the second carbon fiber layer achieves the effect of overlapping adjacent first carbon fiber layers in the direction of vertical stacking, playing a role similar to needling, increasing the friction between the layers inside the carbon fiber preform, enhancing the consolidation ability between layers, improving the delamination resistance, thereby improving the structural stability of the carbon fiber preform, contributing to the improvement of the performance of the carbon fiber material, and at the same time avoiding the losses caused by needling and the problem of reducing the mechanical properties of the carbon fiber material. In the related art, multiple layers of carbon fibers not only need to be stacked but also need to be needled in the vertical stacking direction to connect and reinforce the multiple layers of carbon fibers and improve the stability and mechanical properties of the overall structure. However, the needling stability is poor, affecting the performance of the carbon fiber preform and the carbon fiber material. In this application, by arranging multiple carbon fiber sheets to connect adjacent first carbon fiber layers, the bonding performance between layers is improved, the needling process is avoided, which is beneficial to the improvement and use of the performance of the carbon fiber preform and the carbon fiber material. It can be understood that Figure 1 , Figure 2 is only used to show the internal stacking relationship of the carbon fiber preform and does not represent the surface topography characteristics of the carbon fiber preform.

[0039] In an embodiment of this application, the first carbon fiber layer includes a plurality of first carbon fiber bundles. That is to say, the plurality of first carbon fiber bundles form the first carbon fiber layer through arrangements, weaving, etc. In an embodiment of this application, the first carbon fiber layer includes at least one of unidirectional fabric and two-dimensional fabric. In an embodiment of this application, the plurality of first carbon fiber bundles are arranged along a first direction to form the first carbon fiber layer. At this time, the first carbon fiber layer is unidirectional fabric. In another embodiment of this application, some of the plurality of first carbon fiber bundles are arranged along the first direction and some are arranged along a second direction. The first direction and the second direction have an included angle (that is, the first direction and the second direction are not parallel) to form the first carbon fiber layer. At this time, the first carbon fiber layer is two-dimensional fabric. Specifically, the two-dimensional fabric can include, but is not limited to, at least one of plain fabric, satin fabric, and twill fabric.

[0040] In an embodiment of the present application, the specification of the first carbon fiber bundle is 1K - 24K, which is beneficial to improving the mechanical properties of the carbon fiber preform. That is to say, the first carbon fiber bundle includes one thousand to twenty-four thousand first carbon fiber filaments. Specifically, the specification of the first carbon fiber bundle can be, but is not limited to, 1K, 3K, 4K, 7K, 10K, 12K, 14K, 17K, 19K, 20K, or 23K, etc. In an embodiment, the specification of the first carbon fiber bundle can be 6K - 12K, which is beneficial to further improving the mechanical properties of the carbon fiber preform. In an embodiment of the present application, the diameter of the cross-section of the first carbon fiber filament is 4μm - 8μm. Specifically, the diameter of the cross-section of the first carbon fiber filament can be, but is not limited to, 4μm, 5μm, 6μm, 7μm, or 8μm, etc. In an embodiment of the present application, the areal density of the first carbon fiber layer is 100g / m 2 - 500g / m 2 , which is beneficial to improving the mechanical properties of the carbon fiber preform. Specifically, the areal density of the first carbon fiber layer can be, but is not limited to, 100g / m 2 , 200g / m 2 , 300g / m 2 , 400g / m 2 or 500g / m 2 , etc. In an embodiment of the present application, the tensile strength of the first carbon fiber layer is greater than or equal to 3500MPa. Specifically, the tensile strength of the first carbon fiber layer can be, but is not limited to, 3500MPa, 3800MPa, 4000MPa, 4200MPa, 4500MPa, 4800MPa, or 5000MPa, etc. Specifically, the first carbon fiber layer can select carbon fiber cloth of T300 and above specifications from Toray Industries, Inc., such as T300 carbon fiber cloth, T700 carbon fiber cloth, etc.

[0041] In an embodiment of the present application, when adjacent first carbon fiber layers are both unidirectional fabrics, the extending directions of the first carbon fiber bundles in the two first carbon fiber layers have an included angle. In other words, the adjacent first carbon fiber layers are the first carbon fiber layer A and the first carbon fiber layer B. The extending direction of the first carbon fiber bundle A in the first carbon fiber layer A is the first direction, and the extending direction of the first carbon fiber bundle B in the first carbon fiber layer B is the second direction. The first direction and the second direction have an included angle, so that the mechanical properties of the carbon fiber preform and the carbon fiber material can be improved. In an embodiment of the present application, when adjacent first carbon fiber layers are both unidirectional fabrics, the included angle between the extending directions of the first carbon fiber bundles in the two first carbon fiber layers is 30°-90°. In an embodiment, when adjacent first carbon fiber layers are both unidirectional fabrics, the included angle between the extending directions of the first carbon fiber bundles in the two first carbon fiber layers can be 45°-90°. It can be understood that the included angle in the present application refers to an angle less than or equal to 90°. In a specific embodiment, the adjacent first carbon fiber layers are the first carbon fiber layer A and the first carbon fiber layer B. The first carbon fiber layer A is a 0° unidirectional fabric, and the first carbon fiber layer B is a 90° unidirectional fabric; that is, the extending direction of the first carbon fiber bundle A is the first direction, and the extending direction of the first carbon fiber bundle B is perpendicular to the first direction. In another specific embodiment, the adjacent first carbon fiber layers are the first carbon fiber layer A and the first carbon fiber layer B. The first carbon fiber layer A is a 0° unidirectional fabric, and the first carbon fiber layer B is a 45° unidirectional fabric; that is, the extending direction of the first carbon fiber bundle A is the first direction, and the included angle between the extending direction of the first carbon fiber bundle B and the first direction is 45°.

[0042] In the present application, the number of layers of the first carbon fiber layer in the carbon fiber preform is at least greater than two, and the first carbon fiber layer provides a bearing function for the arrangement of the carbon fiber sheet and the second carbon fiber layer. In an embodiment of the present application, the number of layers of the first carbon fiber layer can be 2-100. Specifically, the number of layers of the first carbon fiber layer can be, but is not limited to, 2, 5, 8, 16, 25, 40, 50, 75, 80, or 95, etc. In an embodiment of the present application, the number of layers of the first carbon fiber layer can be 5-50.

[0043] In an embodiment of the present application, the lateral dimension of the first carbon fiber layer is greater than 50 mm. The lateral dimension of the first carbon fiber layer in the present application refers to the maximum distance between any two points on the surface of the first carbon fiber layer. Specifically, the lateral dimension of the first carbon fiber layer can be, but is not limited to, greater than 60 mm, greater than 70 mm, greater than 80 mm, greater than 90 mm, greater than 100 mm, etc. In an embodiment of the present application, the lateral dimension of the first carbon fiber layer is 80 mm. The first carbon fiber layer in the present application can be a regular shape or an irregular shape, and the specific shape can be selected according to needs. For example, the first carbon fiber layer can be a cuboid or a cuboid-like shape. In the present application, the thickness of the first carbon fiber layer is in millimeters, and the specific thickness can be selected according to needs.

[0044] In the present application, the special setting method of the carbon fiber sheets can enhance the bonding stability between adjacent first carbon fiber layers and improve the mechanical strength of the carbon fiber preform. In the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of multiple carbon fiber sheets is greater than or equal to 30%. That is to say, the number of carbon fiber sheets in the second carbon fiber layer is N1, and the number of carbon fiber sheets in the second carbon fiber layer with an angle greater than or equal to 30° to the first carbon fiber layer is N2, and the ratio of N2 to N1 is greater than or equal to 30%. The angle in the present application is an acute angle or a right angle. The angle between the carbon fiber sheet and the first carbon fiber layer refers to the angle between the surface of the carbon fiber sheet and the surface of the first carbon fiber layer in contact with the carbon fiber sheet, where the surface of the carbon fiber sheet is the surface with the largest area of the carbon fiber sheet; for example, the angle between the carbon fiber sheet and the first carbon fiber layer is Figure 2 α shown in. Specifically, the angle α can be but is not limited to 30°, 40°, 45°, 60°, 70°, 80°, or 90°, etc.; the ratio of the number of carbon fiber sheets with an angle of α or more to the first carbon fiber layer to the number of multiple carbon fiber sheets is greater than or equal to 40%, 45%, 50%, 60%, 70%, 80%, 90%, or 100%, etc. In an embodiment of the present application, in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle of 45°-90° to the first carbon fiber layer to the number of multiple carbon fiber sheets is greater than or equal to 30%, which is beneficial to further improving the structural stability of the carbon fiber preform. In an embodiment of the present application, in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle of 45°-90° to the first carbon fiber layer to the number of multiple carbon fiber sheets is greater than or equal to 50%. In another embodiment of the present application, the angles between multiple carbon fiber sheets in the second carbon fiber layer and the first carbon fiber layer are all 45°-90°.

[0045] In an embodiment of the present application, the carbon fiber sheet includes a plurality of second carbon fiber bundles. That is to say, a plurality of second carbon fiber bundles form a carbon fiber sheet through arrangements, weaving, etc. In an embodiment of the present application, the carbon fiber sheet includes at least one of unidirectional cloth and two-dimensional cloth. In an embodiment of the present application, a plurality of second carbon fiber bundles are arranged in a first direction to form a carbon fiber sheet, and at this time the carbon fiber sheet is unidirectional cloth. In another embodiment of the present application, some of the plurality of second carbon fiber bundles are arranged in a first direction and some are arranged in a second direction, and the first direction and the second direction have an angle (that is, the first direction and the second direction are not parallel) to form a carbon fiber sheet, and at this time the carbon fiber sheet is two-dimensional cloth. Specifically, the two-dimensional cloth can be but is not limited to include at least one of plain cloth, satin cloth, and twill cloth.

[0046] In an embodiment of the present application, the specification of the second carbon fiber bundle is 1K - 24K, which is beneficial to improving the mechanical properties of the carbon fiber preform. That is to say, the second carbon fiber bundle includes one thousand to twenty-four thousand second carbon fiber filaments. Specifically, the specification of the second carbon fiber bundle can be, but is not limited to, 1K, 3K, 4K, 7K, 10K, 12K, 14K, 17K, 19K, 20K, or 23K, etc. In one embodiment, the specification of the second carbon fiber bundle can be 6K - 12K, which is beneficial to further improving the mechanical properties of the carbon fiber preform. In an embodiment of the present application, the diameter of the cross-section of the second carbon fiber filament is 4μm - 8μm. Specifically, the diameter of the cross-section of the second carbon fiber filament can be, but is not limited to, 4μm, 5μm, 6μm, 7μm, or 8μm, etc. In an embodiment of the present application, the areal density of the carbon fiber sheet is 100g / m 2 - 500g / m 2 , which is beneficial to improving the mechanical properties of the carbon fiber preform. Specifically, the areal density of the carbon fiber sheet can be, but is not limited to, 100g / m 2 , 200g / m 2 , 300g / m 2 , 400g / m 2 or 500g / m 2 , etc. In an embodiment of the present application, the tensile strength of the carbon fiber sheet is greater than or equal to 3500MPa. Specifically, the tensile strength of the carbon fiber sheet can be, but is not limited to, 3500MPa, 3800MPa, 4000MPa, 4200MPa, 4500MPa, 4800MPa, or 5000MPa, etc. Specifically, the carbon fiber sheet can select carbon fiber cloth with a specification of T300 or above from Toray Industries, Inc., such as T300 carbon fiber cloth, T700 carbon fiber cloth, etc. In the present application, the material of the first carbon fiber layer and the material of the carbon fiber sheet can be the same or different.

[0047] In this application, the transverse dimension of the carbon fiber sheet is 2.5 mm - 30 mm. The transverse dimension of the carbon fiber sheet in this application refers to the maximum distance between any two points on the surface of the carbon fiber sheet. When the transverse dimension of the carbon fiber sheet is less than 2.5 mm, the carbon fiber sheet is close to granular, and the lapping consolidation effect is weak. When the transverse dimension of the carbon fiber sheet is greater than 30 mm, the size is too large, which will still affect the lapping effect, that is, too large or too small transverse dimension of the carbon fiber sheet will affect the structural stability of the carbon fiber preform; in this application, a carbon fiber sheet with a transverse dimension of 2.5 mm - 30 mm and a first carbon fiber layer with a transverse dimension greater than 50 mm are used, so that the carbon fiber sheet can effectively lap adjacent first carbon fiber layers and improve the structural stability of the carbon fiber preform. Specifically, the transverse dimension of the carbon fiber sheet can be, but is not limited to, 2.5 mm, 5 mm, 8 mm, 10 mm, 13 mm, 15 mm, 17 mm, 20 mm, 23 mm, 25 mm, 27 mm, 30 mm, etc. In an embodiment of this application, the transverse dimension of the carbon fiber sheet can be 5 mm - 20 mm. The carbon fiber sheet in this application can be in a regular shape or an irregular shape, and the specific shape can be selected according to needs. For example, the carbon fiber sheet can be a cuboid, a quasi-cuboid, a cube, a quasi-cube, etc. In this application, the thickness of the carbon fiber sheet is in the millimeter range, and the specific thickness can be selected according to needs.

[0048] In an embodiment of this application, the ratio of the length, width and thickness of the carbon fiber sheet is (2.5 - 10):(2.5 - 6):1, which is beneficial to further improving the mechanical properties of the carbon fiber preform. Specifically, the ratio of the length, width and thickness of the carbon fiber sheet can be, but is not limited to, 2.5:2.5:1, 5:4:1, 8:5:1, 10:6:1, etc. In an embodiment of this application, the length of the carbon fiber sheet is 2.5 mm - 30 mm, the width is 2.5 mm - 18 mm, and the thickness is 1 mm - 3 mm; at this time, the shape of the carbon fiber sheet is a cuboid or a quasi-cuboid, which is beneficial to improving the lapping effect of the carbon fiber sheet, thereby further improving the performance of the carbon fiber preform. Specifically, the length of the carbon fiber sheet can be, but is not limited to, 2.5 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, etc., the width of the carbon fiber sheet can be, but is not limited to, 2.5 mm, 3 mm, 5 mm, 8 mm, 10 mm, 15 mm, 17 mm, etc., and the thickness of the carbon fiber sheet can be, but is not limited to, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm. In an embodiment, the length of the carbon fiber sheet is 2.5 mm - 30 mm, the width is 2.5 mm - 18 mm, the thickness is 1 mm - 3 mm, and the ratio of the length, width and thickness is (2.5 - 10):(2.5 - 6):1, which is beneficial to further improving the mechanical properties of the carbon fiber preform. It can be understood that the carbon fiber cloth can be cut as needed to obtain carbon fiber sheets of the required size.

[0049] In an embodiment of the present application, the orthographic projections of multiple carbon fiber sheets in the second carbon fiber layer on the surface of the first carbon fiber layer completely cover the surface of the first carbon fiber layer. That is to say, relative to the first carbon fiber layer, the carbon fiber sheets lapping it are inclined. The orthographic projections of all the carbon fiber sheets in the second carbon fiber layer on the surface of the first carbon fiber layer completely cover the surface of the first carbon fiber layer, so that the adjacent first carbon fiber layers are lapped by the carbon fiber sheets and the lapping area is large, further improving the bonding performance of the carbon fiber preform.

[0050] In the present application, the second carbon fiber layer includes multiple carbon fiber sheets. The carbon fiber sheets lap adjacent first carbon fiber layers to improve the bonding performance between adjacent first carbon fiber layers. The specific number of carbon fiber sheets can be selected according to the size of the first carbon fiber layer, the size of the carbon fiber sheets and the requirements of the layer laying method. The multiple carbon fiber sheets in the second carbon fiber layer can be arranged at intervals or lapped; arranging the carbon fiber sheets at intervals is beneficial to the infiltration of resin in the preparation of carbon fiber materials and increases the content of carbon materials in the carbon fiber materials. Lapping the carbon fiber sheets can improve the interaction between the carbon fiber sheets, contribute to improving the stability of the inclined setting of the carbon fiber sheets, and further contribute to improving the lapping stability of the carbon fiber sheets. In the carbon fiber preform, at least one layer of the second carbon fiber layer is included between adjacent first carbon fiber layers to improve the stability of the carbon fiber preform and its mechanical properties. Specifically, multiple layers of the second carbon fiber layer can be arranged between adjacent first carbon fiber layers, such as two layers, three layers, etc. The specific number of layers can be selected according to needs.

[0051] In the present application, the carbon fiber preform includes at least two layers of first carbon fiber layers and at least one layer of second carbon fiber layer arranged in a stacked manner. At least one layer of the second carbon fiber layer is provided between adjacent first carbon fiber layers. By lapping adjacent first carbon fiber layers with the second carbon fiber layer including multiple carbon fiber sheets, the stability of the carbon fiber preform is ensured while avoiding the adverse effects of needling. In an embodiment of the present application, the number of layers of the second carbon fiber layer in the carbon fiber preform can be 2 - 100. Specifically, the number of layers of the second carbon fiber layer in the carbon fiber preform can be, but is not limited to, 2, 5, 8, 16, 25, 40, 50, 75, 80 or 95, etc. In an embodiment of the present application, the number of layers of the second carbon fiber layer in the carbon fiber preform can be 5 - 50. The present application does not limit the number of layers of the first carbon fiber layer and the second carbon fiber layer, and only requires that adjacent first carbon fiber layers be connected by the second carbon fiber layer. Please refer to Figure 3 , which is a cross-sectional schematic diagram of the carbon fiber preform provided in another embodiment of the present application. The carbon fiber preform 100 includes a first carbon fiber layer 10 and a second carbon fiber layer 20 arranged in a stacked manner. The outermost sides of the carbon fiber preform 100 are respectively the first carbon fiber layer 10 and the second carbon fiber layer 20. AsFigure 2 As shown, the outermost layer of the carbon fiber preform 100 is the first carbon fiber layer 10 and the second carbon fiber layer 20. The outermost layer of the carbon fiber preform provided in this application can be the first carbon fiber layer or the second carbon fiber layer. In an embodiment of this application, the first carbon fiber layer is located on the outermost side of the carbon fiber preform, which can further improve the mechanical properties of the carbon fiber preform.

[0052] In one embodiment of this application, the carbon fiber preform further includes a carbon coating layer, which coats the first carbon fiber layer and / or the carbon fiber sheet. In an embodiment of this application, the carbon coating layer coats the first carbon fiber bundle, thereby coating the first carbon fiber layer. In another embodiment of this application, the carbon coating layer coats the second carbon fiber bundle, thereby coating the carbon fiber sheet. In one embodiment of this application, the thickness of the carbon coating layer is 0.1μm - 5μm; the carbon coating layer can improve the mechanical properties of the carbon fiber preform and the carbon fiber material. Specifically, the thickness of the carbon coating layer can be, but is not limited to, 0.1μm, 0.5μm, 1μm, 2μm, 3μm, 4μm or 5μm, etc. In one embodiment, the thickness of the carbon coating layer can be 2μm - 4μm, further improving the stability of the carbon fiber preform. In a specific embodiment, the thickness of the carbon coating layer coating the first carbon fiber layer can be 0.5μm. In another specific embodiment, the thickness of the carbon coating layer coating the carbon fiber sheet can be 3μm.

[0053] In one embodiment of this application, the thickness of the carbon fiber preform is 2.5mm - 200mm, which is beneficial to the preparation of carbon fiber materials with good bending strength and shear strength, and is also beneficial to obtaining lightweight carbon fiber materials. Specifically, the thickness of the carbon fiber preform can be, but is not limited to, 2.5mm, 20mm, 50mm, 100mm, 150mm or 200mm, etc. In an embodiment of this application, the thickness of the carbon fiber preform can be 5mm - 100mm. In another embodiment of this application, the thickness of the carbon fiber preform can be 50mm - 150mm.

[0054] The present application also provides a method for preparing a carbon fiber preform, including: laminating at least two first carbon fiber layers and at least one second carbon fiber layer, with at least one second carbon fiber layer disposed between adjacent first carbon fiber layers to obtain a carbon fiber preform, wherein the second carbon fiber layer includes a plurality of carbon fiber sheets, and in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%, the lateral dimension of the first carbon fiber layer is greater than 50 mm, and the lateral dimension of the carbon fiber sheet is 2.5 mm - 30 mm. The method for preparing the carbon fiber preform provided by the present application can prepare the carbon fiber preform in any of the above embodiments. The method for preparing the carbon fiber preform provided by the present application is simple and easy to operate, and can obtain a carbon fiber preform with excellent mechanical properties, which is beneficial to the preparation of carbon fiber materials.

[0055] In one embodiment of the present application, a plurality of carbon fiber sheets can be directly disposed on the first carbon fiber layer to form the second carbon fiber layer. In another embodiment of the present application, after laying a plurality of carbon fiber sheets to form the second carbon fiber layer, it can be directly disposed on the surface of the first carbon fiber layer.

[0056] In one embodiment of the present application, before laminating, carbon deposition can also be performed on the first carbon fiber layer to obtain a first carbon fiber layer coated with a carbon coating layer. The carbon coating layer can serve as a bonding phase and can further improve the density and strength of the carbon fiber preform. In another embodiment of the present application, before laminating, carbon deposition can also be performed on the carbon fiber sheets to obtain carbon fiber sheets coated with a carbon coating layer. Specifically, the first carbon fiber layer and the carbon fiber sheets can be placed in a deposition device for carbon deposition, for example, by chemical vapor deposition. In one example of the present application, the thickness of the carbon coating layer can be 0.1 μm - 5 μm.

[0057] The present application also provides a carbon fiber material, including at least two first carbon fiber layers, at least one second carbon fiber layer, and a carbon material; the first carbon fiber layer and the second carbon fiber layer are laminated; at least one second carbon fiber layer is disposed between adjacent first carbon fiber layers; the second carbon fiber layer includes a plurality of carbon fiber sheets; in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%; the lateral dimension of the first carbon fiber layer is greater than 50 mm; the lateral dimension of the carbon fiber sheet is 2.5 mm - 30 mm. In the present application, the arrangement of the carbon fiber sheets in the first carbon fiber layer and the second carbon fiber layer in the carbon fiber material can be detected by scanning electron microscopy, X-ray, CT scanning, etc.

[0058] In an embodiment of the present application, the carbon material is disposed inside the first carbon fiber layer, inside the second carbon fiber layer, and between the first carbon fiber layer and the second carbon fiber layer. When the carbon material is disposed inside the first carbon fiber, it can coat the first carbon fiber bundle or be disposed in the gaps between the first carbon fiber bundles; when the carbon material is disposed inside the second carbon fiber, it can coat the second carbon fiber bundle, be disposed in the gaps between the second carbon fiber bundles, or be disposed in the gaps between the carbon fiber sheets; the carbon fiber material can also be disposed in the gaps between the first carbon fiber layer and the second carbon fiber layer. The setting of the carbon material improves the strength and density of the carbon fiber material, which is beneficial to the improvement of the mechanical properties of the carbon fiber material. It can be understood that the carbon material coating the first carbon fiber bundle and the second carbon fiber bundle is the above-mentioned carbon coating layer, that is, the carbon material includes the carbon coating layer. In the present application, the carbon material can be granular or continuous.

[0059] In an embodiment of the present application, the mass ratio of the first carbon fiber layer and the second carbon fiber layer in the carbon fiber material is 10%-60%. Specifically, the mass ratio of the first carbon fiber layer and the second carbon fiber layer in the carbon fiber material can be, but is not limited to, 10%, 20%, 30%, 40%, 50% or 60%, etc. In an embodiment of the present application, the mass ratio of the first carbon fiber layer and the second carbon fiber layer in the carbon fiber material is 20%-50%. In another embodiment of the present application, the mass ratio of the first carbon fiber layer and the second carbon fiber layer in the carbon fiber material is 25%-45%.

[0060] In an embodiment of the present application, the carbon material further includes silicon element, which is beneficial to improving the oxidation resistance of the carbon fiber material and is beneficial to the use of the carbon fiber material. In an embodiment of the present application, the carbon fiber includes silicon carbide. Silicon carbide can be dispersed between the first carbon fiber layer and the second carbon fiber layer. In another embodiment of the present application, the carbon material is silicon carbide. That is to say, the carbon material in the carbon fiber preform in the present application can contain part of silicon carbide or all be silicon carbide. In an embodiment of the present application, the mass content of silicon carbide in the carbon fiber material can be 20%-60%, which is beneficial to improving the strength and oxidation resistance of the carbon fiber material. Specifically, the mass content of silicon carbide in the carbon fiber material can be, but is not limited to, 20%, 30%, 40%, 50% or 60%, etc. In an embodiment of the present application, the carbon fiber material further includes elemental silicon. Elemental silicon can be disposed between the first carbon fiber layer and the second carbon fiber layer.

[0061] In an embodiment of the present application, the porosity of the carbon fiber material is less than 20%. Specifically, the porosity of the carbon fiber material can be, but is not limited to, less than 18%, less than 16%, less than 13%, less than 10%, less than 8%, less than 5% or less than 2%, etc. In an embodiment of the present application, when the carbon fiber material has silicon carbide, the porosity of the carbon fiber material is less than 15%.

[0062] In an embodiment of the present application, the flexural strength of the carbon fiber material is 100 MPa - 200 MPa. The carbon fiber material provided by the present application has high flexural strength and good internal bonding force, which is beneficial to the use of the carbon fiber material. Specifically, the flexural strength of the carbon fiber material can be, but is not limited to, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa or 200 MPa, etc. In an embodiment of the present application, the flexural strength of the carbon fiber material can be 120 MPa - 170 MPa.

[0063] In an embodiment of the present application, the shear strength of the carbon fiber material is 10.6 MPa - 20 MPa. The carbon fiber material provided by the present application has high shear strength and good internal bonding force, which is beneficial to the use of the carbon fiber material. Specifically, the shear strength of the carbon fiber material can be, but is not limited to, 10.8 MPa, 10.9 MPa, 11 MPa, 11.5 MPa, 12 MPa, 12.7 MPa, 13 MPa, 13.5 MPa, 13.9 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa or 19 MPa, etc. In an embodiment of the present application, the shear strength of the carbon fiber material can be 12 MPa - 17 MPa.

[0064] In an embodiment of the present application, the mass wear rate of the carbon fiber material after wearing for 120 min at 1000 r / min is less than or equal to 6‰. The carbon fiber material provided by the present application has a small mass wear rate, high strength and a long service life, which is beneficial to the wide application of the carbon fiber material. Specifically, the mass wear rate of the carbon fiber material after wearing for 120 min at 1000 r / min can be, but is not limited to, less than or equal to 6‰, less than or equal to 5‰, less than or equal to 4‰, less than or equal to 3‰, less than or equal to 2‰, less than or equal to 1‰ or less than or equal to 0.5‰, etc. In an embodiment of the present application, the mass wear rate of the carbon fiber material after wearing for 120 min at 1000 r / min is less than or equal to 3‰.

[0065] The present application also provides a preparation method of the carbon fiber material, which can prepare the carbon fiber material in any of the above embodiments. Please refer to Figure 4 , which is a flowchart of the preparation method of the carbon fiber material provided by an embodiment of the present application, including:

[0066] S101: At least two first carbon fiber layers and at least one second carbon fiber layer are stacked, and at least one second carbon fiber layer is provided between adjacent first carbon fiber layers to obtain a carbon fiber preform. The second carbon fiber layer includes a plurality of carbon fiber sheets. In the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%. The lateral dimension of the first carbon fiber layer is greater than 50 mm; the lateral dimension of the carbon fiber sheet is 2.5 mm - 30 mm.

[0067] S102: After the carbon fiber preform is deposited with carbon, it is impregnated with resin, and then obtained as a carbon fiber material after curing and carbonization treatment.

[0068] The preparation method of the carbon fiber material provided by this application is simple and convenient to operate, and a carbon fiber material with excellent mechanical properties, such as bending strength and shear strength, can be obtained, which is beneficial to the use of the carbon fiber material. Among them, S101 can refer to the relevant description in the above carbon fiber preform preparation method and will not be elaborated here.

[0069] In S102, after carbon deposition, the carbon coats the first carbon fiber layer and the second carbon fiber layer, and there may also be some dispersed between the first carbon fiber layer and the second carbon fiber layer; after resin impregnation, the resin fills the pores in the carbon fiber preform after carbon deposition; after curing and carbonization treatment, the carbon formed by the resin is evenly dispersed between the first carbon fiber layer and the second carbon fiber layer. The carbon fiber preform serves as the skeleton of the carbon fiber material, the deposited carbon can serve as a bonding phase to enhance strength, and the carbon formed by the resin can serve as a filling phase to enhance density and strength. It can be understood that the deposited carbon and the carbon formed by the resin are the carbon materials in the carbon fiber material.

[0070] In an embodiment of this application, carbon deposition can be carried out by chemical vapor deposition. Specifically, chemical vapor deposition includes thermal chemical vapor deposition, plasma chemical vapor deposition (PCVD), atmospheric pressure chemical vapor deposition, low-pressure chemical vapor deposition, etc. In an embodiment of this application, the mass ratio of the deposited carbon in the carbon fiber material is 10% - 80%. Specifically, the mass ratio of the deposited carbon in the carbon fiber material can be but is not limited to 20%, 30%, 40%, 50%, 60% or 70%, etc. In an embodiment of this application, the mass ratio of the deposited carbon in the carbon fiber material can be 20% - 50%.

[0071] In an embodiment of the present application, the resin includes at least one of a thermosetting resin and a thermoplastic resin. The resin is filled in the gaps of the carbon fiber preform after carbon deposition to fix it, which can enhance the density and strength of the carbon fiber preform. Specifically, the thermosetting resin may but is not limited to include at least one of unsaturated polyester resin, epoxy resin, phenolic resin, melamine formaldehyde resin, furan resin, polybutadiene resin, and silicone resin; the thermoplastic resin may but is not limited to include at least one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, or rubber. The curing process can be selected according to the resin properties and will not be elaborated here. In an embodiment of the present application, the mass ratio of the carbon formed by the resin in the carbon fiber material is 10%-50%. Specifically, the mass ratio of the deposited carbon in the carbon fiber material may but is not limited to be 20%, 30%, 40%, or 50%, etc. In an embodiment of the present application, the mass ratio of the carbon formed by the resin in the carbon fiber material is 20%-45%.

[0072] In an embodiment of the present application, the carbonization temperature is 500°C - 1500°C, and the carbonization time is 1h - 10h. Specifically, the carbon fiber preform impregnated and cured with resin can be placed under the condition of 500°C - 1500°C and maintained for 1h - 10h in a vacuum or an inert gas atmosphere such as argon, helium, etc., so that the resin inside the carbon fiber preform is converted into carbon. Specifically, the carbonization temperature may but is not limited to be 500°C, 700°C, 900°C, 1100°C, 1300°C, or 1500°C, etc., and the carbonization time may but is not limited to be 1h, 3h, 5h, 7h, 9h, or 10h, etc. In an embodiment of the present application, the carbonization temperature can be 800°C - 1200°C, and the carbonization time can be 5h - 8h, which can further accelerate the carbonization speed and reduce the preparation cost.

[0073] In an embodiment of the present application, graphitization treatment is further included after carbonization treatment. The graphitization treatment temperature is 1800°C - 3000°C, and the graphitization treatment time is 1h - 10h. Specifically, the carbonized carbon fiber preform can be placed under the condition of 1800°C - 3000°C and maintained for 1h - 10h in a vacuum or an inert gas atmosphere such as argon, helium, etc. The carbon in the carbon fiber preform is gradually converted into graphite, which further improves the overall chemical stability, lubricity, and abrasion resistance of the material. Specifically, the graphitization treatment temperature may but is not limited to be 1800°C, 2000°C, 2200°C, 2400°C, 2600°C, 2800°C, or 3000°C, etc., and the graphitization treatment time may but is not limited to be 1h, 3h, 5h, 7h, 9h, or 10h, etc. In an embodiment of the present application, the graphitization treatment temperature can be 2000°C - 2500°C, and the graphitization treatment time can be 5h - 8h, which can further accelerate the graphitization speed and improve the material structure stability.

[0074] In one embodiment of the present application, after the graphitization treatment, a ceramization treatment is further included to improve the oxidation resistance of the carbon fiber material through the ceramization treatment. In one example of the present application, the temperature of the ceramization treatment is 1400°C - 2400°C, and the ceramization time is 0.5 h - 10 h. Specifically, the temperature of the ceramization treatment can be, but is not limited to, 1400°C, 1600°C, 1800°C, 2000°C, 2200°C, or 2400°C, etc., and the time of the ceramization treatment can be, but is not limited to, 0.5 h, 1 h, 2 h, 3 h, 4 h, or 5 h, etc. Through the ceramization treatment, the carbon deposited and the carbon formed by the resin react to form silicon carbide, further improving the performance of the carbon fiber material. Specifically, the carbon fiber preform after the graphitization treatment can be mixed with silicon powder and placed under the condition of 1400°C - 2400°C, and maintained for 0.5 h - 10 h in a vacuum or in an atmosphere of an inert gas such as argon, helium, etc. In one example, the temperature of the ceramization treatment can be 1600°C - 2200°C, and the time of the ceramization treatment can be 2 h - 4 h, which is beneficial to accelerating the ceramization process and improving the stability of the product. In one example of the present application, other additives can also be added during the ceramization treatment, which can be, but is not limited to, silicon carbide, boron oxide, etc. In one example of the present application, the porosity of the carbon fiber material obtained after the ceramization treatment is less than 15%, further improving the material performance.

[0075] The present application also provides a structural member, and the material of the structural member includes the carbon fiber material in any one of the above embodiments, or includes the carbon fiber material obtained by any one of the above embodiments. The structural member provided by the present application is light in weight, high in strength, and excellent in mechanical properties, which is beneficial to the use of the structural member. The present application does not limit the type, composition, and application of the structural member.

[0076] In one embodiment of the present application, the structural member includes a brake disc. The brake disc made of the carbon fiber material provided by the present application has a low preparation cost, good mechanical properties, and a long service life. In one example of the present application, the brake disc is an aircraft brake disc. That is, the carbon fiber material can be used as the material of the aircraft brake disc. In another example of the present application, the brake disc is an automobile brake disc. That is, the carbon fiber material can be used as the material of the automobile brake disc. Specifically, the carbon fiber material obtained after the ceramization treatment can be used as the material of the automobile brake disc to prevent the oxidation of the automobile brake disc and improve its oxidation resistance.

[0077] The present application also provides a braking system, and the braking system includes the structural member in any one of the above embodiments, which is beneficial to improving the use performance of the braking system. In one embodiment of the present application, the structural member includes a brake disc, and the braking system may further include a brake caliper bracket, a front brake housing, and a friction pad.

[0078] The present application also provides a means of transportation, including the braking system in any of the above embodiments, which is conducive to enhancing the market competitiveness of the means of transportation. Specifically, the means of transportation can be, but is not limited to, an aircraft, a vehicle, etc.

[0079] The effects of the technical solution of the present application will be further described below through specific examples.

[0080] Example 1

[0081] Carbon fiber filaments with a cross-sectional diameter of 8 μm are used to fabricate a 12K carbon fiber bundle. The carbon fiber bundle is fabricated into a unidirectional fabric. The tensile strength of the unidirectional fabric is 4000 MPa, and the areal density is 500 g / m 2 . The unidirectional fabric is cut to obtain a first carbon fiber layer with a transverse dimension greater than 50 mm and a plurality of carbon fiber sheets with a length of 5 mm, a width of 5 mm, and a thickness of 1 mm. The plurality of carbon fiber sheets are stacked on the first carbon fiber layer to form a second carbon fiber layer. The orthographic projection of the plurality of carbon fiber sheets on the first carbon fiber layer completely covers the surface of the first carbon fiber layer. The ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%. Two layers of the first carbon fiber layer and one layer of the second carbon fiber layer are alternately laminated to obtain a carbon fiber preform with a thickness of 4 mm.

[0082] Example 2

[0083] It is substantially the same as Example 1, except that carbon fiber filaments with a cross-sectional diameter of 4 μm are used to fabricate a 1K carbon fiber bundle, and the carbon fiber bundle is fabricated into a plain weave fabric. The plain weave fabric is cut to obtain a plurality of carbon fiber sheets, and the ratio of the number of carbon fiber sheets with an angle greater than or equal to 45° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets in the second carbon fiber layer is greater than or equal to 30%.

[0084] Example 3

[0085] It is substantially the same as Example 1, except that carbon fiber filaments with a cross-sectional diameter of 8 μm are used to fabricate a 12K carbon fiber bundle, and the carbon fiber bundle is fabricated into a twill fabric with an areal density of 200 g / m 2 . The twill fabric is cut to obtain a first carbon fiber layer with a transverse dimension greater than 50 mm and a plurality of carbon fiber sheets with a length of 2.5 mm, a width of 2.5 mm, and a thickness of 1 mm, and the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets in the second carbon fiber layer is greater than or equal to 50%.

[0086] Example 4

[0087] It is substantially the same as Example 1, except that the carbon fiber sheets have a length of 5 mm, a width of 8 mm, and a thickness of 1.5 mm.

[0088] Example 5

[0089] It is substantially the same as Example 1, except that the carbon fiber sheet has a length of 15 mm, a width of 6 mm, and a thickness of 4 mm.

[0090] Example 6

[0091] It is substantially the same as Example 1, except that the carbon fiber preform includes 3 layers of first carbon fiber layers and 4 layers of second carbon fiber layers that are alternately stacked.

[0092] Examples 7 - 12

[0093] Examples 7 - 12 respectively use the carbon fiber preforms prepared in Examples 1 - 6. After depositing carbon on the carbon fiber preforms by chemical vapor deposition, they are immersed in phenolic resin. After curing, in a vacuum environment, they are carbonized at 500 °C for 1 h, and then graphitized at 1800 °C for 1 h to obtain carbon fiber materials.

[0094] Example 13

[0095] Using the carbon fiber preform prepared in Example 1, after depositing carbon on the carbon fiber preform by chemical vapor deposition, it is immersed in phenolic resin. After curing, in a vacuum environment, it is carbonized at 500 °C for 1 h, and then graphitized at 1800 °C for 1 h. Finally, it is mixed with elemental silicon powder and ceramized at 1600 °C for 2 h to obtain carbon fiber materials.

[0096] Comparative Example 1

[0097] The 3 - layer first carbon fiber layers used in Example 1 are stacked to form a carbon fiber preform, and a carbon fiber material is formed through the same processing technology as in Example 7.

[0098] Comparative Example 2

[0099] The 3 - layer first carbon fiber layers used in Example 1 are stacked to form a carbon fiber preform, and a carbon fiber material is formed through the same processing technology as in Example 13.

[0100] Comparative Example 3

[0101] It is substantially the same as Example 1, except that the ratio of the number of carbon fiber sheets in the second carbon fiber layer with an angle greater than or equal to 30° to the number of the first carbon fiber layer to the number of multiple carbon fiber sheets is 20%. A carbon fiber preform is prepared, and a carbon fiber material is formed through the same processing technology as in Example 7.

[0102] Comparative Example 4

[0103] It is substantially the same as Example 1, except that the lateral dimension of the first carbon fiber layer is 30 mm, a carbon fiber preform is obtained, and a carbon fiber material is formed through the same processing technology as in Example 7.

[0104] Comparative Example 5

[0105] It is substantially the same as Example 1, except that the length of the carbon fiber sheet is 1 mm, the width is 1 mm, and the thickness is 0.5 mm, a carbon fiber preform is obtained, and a carbon fiber material is formed through the same processing technology as in Example 7.

[0106] Comparative Example 6

[0107] It is substantially the same as Example 1, except that the length of the carbon fiber sheet is 40 mm, the width is 20 mm, and the thickness is 2 mm, a carbon fiber preform is obtained, and a carbon fiber material is formed through the same processing technology as in Example 7.

[0108] Performance testing

[0109] The carbon fiber materials obtained in the above Examples 7 - 13 and Comparative Examples 1 - 6 are processed into structural parts (brake discs). The flexural strength of the structural parts is detected according to the fine ceramics flexural strength test method of GB / T6569 - 2006, and the shear strength of the structural parts is detected according to the test method for short beam strength of composite laminates of ASTM D2344 / D2344M. The results are shown in Table 1.

[0110] The carbon fiber materials obtained in the above Examples 7 - 13 and Comparative Examples 1 - 6 are processed into structural parts (brake discs). A constant - speed friction and wear test is carried out on the structural parts using an MD - 240 constant - speed friction machine. The test conditions are a rotation speed of 1000 r / min and a time of 120 min. The mass wear rate (‰) = (the mass of the structural part before the wear test - the mass of the structural part after the wear test) / the mass of the structural part before the wear test * 1000. The calculation results of the mass wear rate are shown in Table 1.

[0111] Table 1 Performance test results

[0112]

[0113]

[0114] It can be seen that, compared with the examples, the second carbon fiber layer is not used in Comparative Example 1 and Comparative Example 2, and their flexural strength is slightly poor, the shear strength is very low, the mass wear rate is high, and the comprehensive performance of the carbon fiber material is not good; compared with the examples, the number of inclined carbon fiber sheets in the second carbon fiber layer in Comparative Example 3 is small, and it cannot effectively improve the flexural strength and shear strength of the carbon fiber material and reduce the mass wear rate of the carbon fiber; compared with the examples, in Comparative Examples 4-6, the sizes of the first carbon fiber layer and the carbon fiber sheets are smaller or larger, and the improvement of the flexural strength and shear strength of the carbon fiber material is limited. Compared with the comparative examples, the carbon fiber materials prepared in Examples 7-13 have high flexural strength, good shear strength, low mass wear rate, and excellent comprehensive performance, which is beneficial to the use of the carbon fiber material; compared with Example 12, the shear strength of the carbon fiber material after ceramization in Example 13 has increased. Therefore, the carbon fiber preform prepared in this application has excellent bonding performance and mechanical properties, which is beneficial to its use.

[0115] The above are exemplary embodiments of the present application, but should not be construed as limiting the scope of the present application. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present application.

Claims

1. A carbon fiber preform, characterized in that, It includes at least two first carbon fiber layers and at least one second carbon fiber layer which are stacked; at least one second carbon fiber layer is provided between adjacent first carbon fiber layers; the second carbon fiber layer includes a plurality of carbon fiber sheets; in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%; the transverse dimension of the first carbon fiber layer is greater than 50 mm; the transverse dimension of the carbon fiber sheet is 2.5 mm - 30 mm.

2. The carbon fiber preform according to claim 1, wherein, The angles between the plurality of carbon fiber sheets and the first carbon fiber layer are all 45° - 90°.

3. The carbon fiber preform according to claim 1, characterized in that, The carbon fiber sheet has a length of 2.5 mm - 30 mm, a width of 2.5 mm - 18 mm, and a thickness of 1 mm - 3 mm.

4. The carbon fiber preform according to claim 1, characterized in that, The thickness of the carbon fiber preform is 2.5 mm - 200 mm.

5. A method for preparing a carbon fiber preform, characterized in that, It includes: At least two first carbon fiber layers and at least one second carbon fiber layer are stacked, and at least one second carbon fiber layer is provided between adjacent first carbon fiber layers to obtain a carbon fiber preform, wherein the second carbon fiber layer includes a plurality of carbon fiber sheets, in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%, the transverse dimension of the first carbon fiber layer is greater than 50 mm, and the transverse dimension of the carbon fiber sheet is 2.5 mm - 30 mm.

6. A carbon fiber material, characterized in that, It includes at least two first carbon fiber layers, at least one second carbon fiber layer and a carbon material; the first carbon fiber layer and the second carbon fiber layer are stacked; at least one second carbon fiber layer is provided between adjacent first carbon fiber layers; the second carbon fiber layer includes a plurality of carbon fiber sheets; in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%; the transverse dimension of the first carbon fiber layer is greater than 50 mm, and the transverse dimension of the carbon fiber sheet is 2.5 mm - 30 mm.

7. The carbon fiber material according to claim 6, wherein, The carbon material further includes silicon element.

8. The carbon fiber material according to claim 6 or 7, characterized in that, The bending strength of the carbon fiber material is 100 MPa - 200 MPa.

9. The carbon fiber material according to claim 6 or 7, characterized in that The shear strength of the carbon fiber material is 10.6 MPa - 20 MPa.

10. The carbon fiber material according to claim 6 or 7, characterized in that, The mass wear rate of the carbon fiber material after wearing for 120 min at 1000 r / min is less than or equal to 6‰.

11. A preparation method of a carbon fiber material, characterized in that, It includes: At least two first carbon fiber layers and at least one second carbon fiber layer are stacked, and at least one second carbon fiber layer is provided between adjacent first carbon fiber layers to obtain a carbon fiber preform, wherein the second carbon fiber layer includes a plurality of carbon fiber sheets, in the second carbon fiber layer, the ratio of the number of carbon fiber sheets with an angle greater than or equal to 30° to the first carbon fiber layer to the number of the plurality of carbon fiber sheets is greater than or equal to 30%, the transverse dimension of the first carbon fiber layer is greater than 50 mm, and the transverse dimension of the carbon fiber sheet is 2.5 mm - 30 mm; The carbon fiber preform is deposited with carbon, impregnated with resin, and then obtained the carbon fiber material after curing and carbonization treatment.

12. The preparation method according to claim 11, characterized in that, After the carbonization treatment, graphitization treatment is further included. The temperature of the graphitization treatment is 1,800°C - 3,000°C, and the time is 1h - 10h; After the graphitization treatment, ceramization treatment is further included. The temperature of the ceramization treatment is 1,400°C - 2,400°C, and the time is 0.5h - 10h.

13. A structural member, characterized in that, The material of the structural member includes the carbon fiber material described in any one of claims 6 - 10 or the carbon fiber material prepared by the preparation method described in any one of claims 11 - 12.

14. The structural member according to claim 13, wherein, The structural member includes a brake disc.

15. A braking system, characterized in that, The braking system includes the structural member described in any one of claims 13 - 14.

16. A vehicle, characterized in that, The vehicle includes the braking system described in claim 15.

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