A carbon / carbon-silicon carbide composite material and preparation method thereof

Abstract

The present application discloses a carbon / carbon-silicon carbide composite material and a preparation method, comprising a plurality of fiber layers and a plurality of carbon fiber rods arranged in a stacked manner, wherein the carbon fiber rods are longitudinally interspersed with the plurality of stacked fiber layers; the fiber layers include short fiber filaments, a silicon carbide matrix and a carbon matrix, and the silicon carbide matrix and the carbon matrix are distributed in the gaps between the short fiber filaments. The plurality of fiber layers stacked in the present application use short fiber filaments to form a loose and mutually overlapping small silk screen, and the silicon carbide matrix and the carbon matrix are distributed in the gaps between the short fiber filaments, which can form a good fiber / carbon matrix interface, while improving the distribution uniformity of the carbon matrix and the silicon carbide matrix, which is conducive to improving the mechanical properties of the carbon / carbon-silicon carbide composite material; and carbon fiber rods are longitudinally interspersed between the plurality of stacked fiber layers, which can improve the interlayer bonding strength and mechanical properties of the carbon / carbon-silicon carbide composite material.

Description

Technical Field

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

[0002] Carbon / carbon-silicon carbide composites (C / C-SiC) offer excellent comprehensive properties, such as low density, high strength, high specific modulus, corrosion resistance, and wear resistance. They are an advanced composite material developed from C / C composites. By partially replacing the original carbon matrix with a silicon carbide matrix, they possess enhanced oxidation resistance and wear resistance, enabling their use in harsh environments such as high heat flux, strong erosion, and ablation. They hold broad application prospects in aviation, aerospace, transportation, and other fields.

[0003] Currently, the main processes for preparing C / C-SiC composites include liquid-phase melt siliconization (LSI), precursor conversion (LPI), chemical vapor infiltration (CVI) and their combinations. However, the above processes either cause severe damage to the fibers, or the bonding strength between the fibers and the matrix is ​​not high, or the silicon carbide matrix is ​​easily densified, resulting in uneven distribution and poor material performance. Summary of the Invention

[0004] In response to the problems existing in the above-mentioned prior art, the present application provides a carbon / carbon-silicon carbide composite material and a preparation method thereof. The technical solution is as follows:

[0005] On the one hand, the present application provides a carbon / carbon-silicon carbide composite material, comprising a plurality of stacked fiber layers and a plurality of carbon fiber rods, wherein the carbon fiber rods are longitudinally interspersed in the plurality of stacked fiber layers; the fiber layers comprise short fiber filaments, a silicon carbide matrix and a carbon matrix, and the silicon carbide matrix and the carbon matrix are distributed in the gaps between the short fiber filaments.

[0006] Furthermore, the fiber layer satisfies at least one of the following characteristics:

[0007] In the same fiber layer, the short fiber filaments are overlapped with each other to form a mesh overlap structure;

[0008] The length of the short fiber filaments is 20 mm to 70 mm.

[0009] Furthermore, the carbon fiber rod satisfies at least one of the following characteristics:

[0010] The longitudinal length of the carbon fiber rod is greater than the total thickness of the multiple stacked fiber layers;

[0011] The diameter of the carbon fiber rod is 0.22mm to 2mm;

[0012] On the same fiber layer, a plurality of carbon fiber rods are arranged in a grid shape;

[0013] On the same edge of the fiber layer, the transverse span between two adjacent carbon fiber rods is 10 mm to 100 mm.

[0014] Furthermore, the carbon / carbon-silicon carbide composite material satisfies at least one of the following characteristics:

[0015] The density of the carbon / carbon-silicon carbide composite material is greater than or equal to a preset density, and the preset density is 1.8 g / cm 3 ~2.5g / cm 3 ;

[0016] The flexural strength of the carbon / carbon-silicon carbide composite material is greater than or equal to a preset flexural strength, and the preset flexural strength is 250 MPa to 300 MPa;

[0017] The interlaminar shear strength of the carbon / carbon-silicon carbide composite material is greater than or equal to a preset interlaminar shear strength, and the preset interlaminar shear strength is 15 MPa to 25 MPa.

[0018] On the other hand, the present application also provides a carbon / carbon-silicon carbide composite material for preparing the carbon / carbon-silicon carbide composite material as described in any one of the above items, comprising:

[0019] Dispersing short fiber filaments and modified silicon carbide in deionized water to obtain a mixed solution;

[0020] The mixed solution is placed in a filter tank for suction filtration, so that the mixed solution forms multiple stacked fiber layers to obtain a prefabricated structure; a plurality of carbon fiber rods are provided in the filter tank; in the prefabricated structure, the carbon fiber rods are longitudinally interspersed with the multiple stacked fiber layers;

[0021] The prefabricated structure is immersed in a resin solution, filtered and dried to obtain a prepreg; the resin solution includes phenolic resin;

[0022] The prepreg is post-processed to obtain a carbon / carbon-silicon carbide composite material; during the post-processing process, the phenolic resin is converted into a carbon matrix, and the modified silicon carbide is converted into a silicon carbide matrix; in the fiber layer of the carbon / carbon-silicon carbide composite material, the carbon matrix and the silicon carbide matrix are distributed in the gaps between the short fiber filaments.

[0023] Furthermore, the short fiber filaments are prepared by the following steps:

[0024] heat-treating the carbon fiber bundle to obtain desized carbon fiber;

[0025] The desized carbon fibers are dispersed by air flow to obtain the short fiber filaments; the length of the short fiber filaments is 20 mm to 70 mm.

[0026] Furthermore, before dispersing the short fiber filaments and modified silicon carbide in deionized water to obtain a mixed solution, the method further comprises:

[0027] Silicon carbide powder is modified by a hydrolysis solution to obtain modified silicon carbide; the surface of the silicon carbide powder in the modified silicon carbide is covered with a silicon dioxide layer; the hydrolysis solution includes a precursor of a silica sol, and the precursor of the silica sol includes at least one of ethyl orthosilicate, trimethylethoxysilane, methyltrimethoxysilane, dimethyldiethoxysilane and sodium silicate, and the precursor of the silica sol undergoes a condensation reaction on the surface of the silicon carbide to form the silicon dioxide layer.

[0028] Furthermore, the mixed solution satisfies at least one of the following characteristics:

[0029] The mass ratio of the short fiber filaments to the deionized water is 1:10 to 1:100;

[0030] The mass ratio of the short fiber filaments to the modified silicon carbide is 2:1 to 15:1;

[0031] The modified silicon carbide further comprises one or more of silicon ceramic powder and silicon nitride ceramic powder, and the particle size of the silicon ceramic powder and the silicon nitride ceramic powder is less than or equal to 50 μm;

[0032] The mixed solution further comprises a dispersant, which comprises one or more of hydroxypropyl methylcellulose, hydroxyethyl methylcellulose and polyethylene glycol;

[0033] The mass ratio of the dispersant to the deionized water is 1:50 to 1:250.

[0034] Furthermore, the resin solution satisfies at least one of the following characteristics:

[0035] The phenolic resin includes one or more of PF8402, PF8218, PF9501, and boron phenolic modified resin;

[0036] The resin solution further comprises a silane coupling agent, and the silicon dioxide layer in the modified silicon carbide can be chemically bridged with the phenolic resin through the silane coupling agent;

[0037] The silane coupling agent includes one or more of KH-550, KH-560, and KH-792;

[0038] The mass proportion of the silane coupling agent in the resin solution is 0.1% to 0.7%;

[0039] The viscosity of the resin solution is 100 mPa·s to 2000 mPa·s.

[0040] Furthermore, in the post-processing process, the method further comprises:

[0041] performing a carbonization treatment on the prepreg so that the phenolic resin forms a carbon matrix to obtain a carbonized body;

[0042] The carburized body is subjected to a silicidation treatment so that the silicon dioxide layer and at least a portion of the carbon matrix undergo a silicidation reaction to generate silicon carbide, thereby obtaining the carbon / carbon-silicon carbide composite material.

[0043] Furthermore, before post-processing the prepreg to obtain the carbon / carbon-silicon carbide composite material, the method further comprises:

[0044] The prepreg is subjected to a curing treatment.

[0045] Furthermore, the post-treatment further includes at least one of a densification treatment and a purification treatment, the densification treatment includes at least one of vapor deposition densification and liquid phase densification, and the temperature of the purification treatment is 1800°C to 2400°C.

[0046] The implementation of this application has the following beneficial effects:

[0047] In the carbon / carbon-silicon carbide composite material of the present application, the multiple stacked fiber layers use short fiber filaments to form a loose and overlapping small wire mesh, and the silicon carbide matrix and the carbon matrix are distributed in the gaps between the short fiber filaments, which can form a good fiber / carbon matrix interface and at the same time improve the distribution uniformity of the carbon matrix and the silicon carbide matrix, which is beneficial to improving the mechanical properties of the carbon / carbon-silicon carbide composite material; and, carbon fiber rods are longitudinally interspersed between the multiple stacked fiber layers, which can greatly improve the interlayer bonding strength and mechanical properties of the carbon / carbon-silicon carbide composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in the embodiments, wherein identical components are denoted by identical reference numerals. Obviously, the drawings described below are merely some embodiments of this application, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0049] Figure 1 A schematic structural diagram of a carbon / carbon-silicon carbide composite material provided in an embodiment of the present application;

[0050] Figure 2A logic diagram of a method for preparing a carbon / carbon-silicon carbide composite material provided in an embodiment of the present application;

[0051] Figure 3 A logic diagram of a method for forming short fiber filaments provided in an embodiment of the present application;

[0052] Figure 4 A logic diagram of a method for forming modified silicon carbide provided in an embodiment of the present application;

[0053] Figure 5 A logic diagram of post-processing provided in an embodiment of the present application.

[0054] Wherein, the reference numerals correspond to:

[0055] 1- short fiber filament, 2- silicon carbide matrix, 3- carbon matrix, 4- carbon fiber rod. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments, and therefore should not be understood as limiting this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0057] It should be noted that in the description of this application, for the following defined terms, these definitions should be applied unless a different definition is given in the claims or elsewhere in this specification. All numerical values, whether or not explicitly indicated, are defined herein as being modified by the term "about". The term "about" generally refers to a numerical range that a person of ordinary skill in the art would consider to be equivalent to the stated value to produce substantially the same properties, functions, results, etc. A numerical range indicated by a low value and a high value is defined to include all numerical values ​​included in the numerical range and all subranges included in the numerical range.

[0058] It should be noted that the terms "first", "second", etc. in the specification, claims, and drawings of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the objects used in this way can be interchangeable where appropriate, so that the embodiments of the present application can be implemented in a sequence other than the following diagrams or the following descriptions. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, or product comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, methods, or products.

[0059] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part. And when the second element, component, region, layer, or part is discussed, it does not necessarily mean that the first element, component, region, layer, or part is present in the present application.

[0060] Among the current processes for preparing C / C-SiC composite materials, the CVI method uses a gaseous precursor as raw material and introduces a silicon carbide matrix phase through high-temperature cracking and deposition. However, the densification rate of the silicon carbide matrix is ​​low, the production cycle is long, and the manufacturing cost is high. The precursor impregnation cracking process (PIP) uses a polycarbosilane solution for impregnation, and then obtains the silicon carbide matrix phase through drying and high-temperature cracking. The fiber damage is small, but the production cycle is long, the precursor pyrolysis yield is very low, the cost is high, and the process control is difficult. The LSI method produces silicon carbide by melting silicon element at high temperature and then reacting it with carbon. Although it has a short cycle and low cost, it is easy for some of the reinforced carbon fibers to participate in the siliconization reaction at high temperatures, causing fiber damage. In addition, after its liquid silicon penetrates into the carbon / carbon composite material blank with a porous structure, it contacts with pyrolytic carbon to generate silicon carbide and form a silicon carbide layer. The subsequent reaction continues through the diffusion of carbon atoms into the silicon melt. However, some gaps between the preform filaments are large. As the silicon carbide layer thickens, the diffusion path of carbon atoms is too long, the silicon carbide generation rate decreases, and some silicon elements do not participate in the reaction, so that elemental carbon is easily retained, affecting the material properties.

[0061] Moreover, most carbon fiber matrices currently adopt a carbon fiber needle-punched preform structure, and first densify it with a carbon matrix to a certain degree before introducing a silicon carrier. However, since the carbon fiber needle-punched preform is made of short fibers "pinned" between the carbon cloth layer and the mesh layer, the interlayer stacking density is uneven and the pore size distribution is also uneven. When the silicon-containing carrier is added to the densified carbon fiber preform, a series of "bottleneck effects" will be generated due to the uneven pore size distribution, resulting in a complex process for introducing the silicon-containing carrier into the preform with a certain degree of carbon matrix densification. There is a common problem of uneven density of the carbon matrix and the silicon carbide matrix generated by it. Moreover, the larger the size, the greater the density gradient, and the more difficult it is to evenly distribute and fill, which in turn causes uneven distribution of the silicon carbide matrix. Secondly, traditional reinforced carbon fibers contain a large number of large carbon fiber tows, and the gaps inside the tows are very small. It is difficult to completely impregnate and fill the densified carbon matrix precursor and the silicon-containing carrier, resulting in insufficient bonding at the fiber / matrix interface, affecting performance.

[0062] Some improved technologies use SiC ceramic slurry to add into the carbon fiber preform to avoid fiber damage and silicon residue caused by high-temperature siliconization reaction, but the process of adding such ceramic slurry is complicated, and it is also difficult to achieve uniform distribution. In addition, the interface bonding between the SiC ceramic phase and the resin is poor, which will lead to poor interface bonding between the silicon carbide matrix phase and the carbon matrix phase. Other improved technologies propose to use organic binders to add carbon powder or ceramic powder to coat silicon powder, and then perform melt siliconization treatment to improve the fiber damage and silicon residue problems. It is also difficult to completely solve the problem of uniform distribution of the silicon carbide matrix.

[0063] It can be seen that the key to the existing C / C-SiC composite material preparation process technology is: 1) minimizing fiber damage; 2) forming appropriate bonding strength at the fiber / matrix (F / M) interface; 3) overcoming the "bottleneck effect" of matrix densification; and 4) low preparation cost.

[0064] In response to at least one of the above-mentioned technical problems, an embodiment of the present application provides a carbon / carbon-silicon carbide composite material and a preparation method. The preparation method of the carbon / carbon-silicon carbide composite material is used to prepare the carbon / carbon-silicon carbide composite material. The fiber damage in the carbon / carbon-silicon carbide composite material is less, the bonding strength between the fiber and the matrix interface is high, and it can also effectively overcome the bottleneck effect of matrix densification and reduce the preparation cost.

[0065] The following is in conjunction with the instructions Figure 1 The carbon / carbon-silicon carbide composite material of the embodiment of the present application is introduced in detail.

[0066] like Figure 1 As shown, the carbon / carbon-silicon carbide composite material includes a plurality of fiber layers and a plurality of carbon fiber rods 4 stacked together, wherein the fiber layer includes short fiber filaments 1, a silicon carbide matrix 2 and a carbon matrix 3, the short fiber filaments 1 are in the form of fine filaments, and the short fiber filaments 1 in each fiber layer are randomly overlapped to form a small mesh, so that the silicon carbide matrix 2 and the carbon matrix 3 can be evenly distributed in the gaps between the short fiber filaments 1, while forming a good fiber / carbon matrix interface, greatly improving the distribution uniformity of the silicon carbide matrix 2 and the carbon matrix 3, which is beneficial to improving the mechanical properties of the carbon / carbon-silicon carbide composite material; and, the carbon fiber rods 4 are longitudinally interspersed in the multiple stacked fiber layers, which can enhance the structural strength of the carbon / carbon-silicon carbide composite material in the longitudinal direction, greatly improving the interlayer bonding strength and mechanical properties of the carbon / carbon-silicon carbide composite material.

[0067] Among them, the short fiber filaments 1 are obtained by dispersing the carbon fiber bundles, are in the shape of fine filaments, are small in size, and have relatively uniform dispersion in the gaps, which facilitates the uniform filling of the carbon matrix 3 and the silicon carbide matrix 2 in the gaps; the carbon matrix 3 is a carbon material dispersed in the carbon / carbon-silicon carbide composite material, and at least part of the carbon matrix in the carbon matrix 3 is obtained by carbonization reaction based on phenolic resin, and part of the carbon matrix is ​​a carbon matrix added by subsequent densification treatment; the silicon carbide matrix 2 is a silicon carbide material dispersed in the carbon / carbon-silicon carbide composite material, and part of the silicon carbide matrix in the silicon carbide matrix 2 is obtained by retaining the silicon carbide powder in the modified silicon carbide raw material, and part of the silicon carbide matrix is ​​generated by a micro-siliconization reaction between the silicon dioxide layer covering the surface of the silicon carbide powder in the modified silicon carbide and part of the carbon matrix in the carbon matrix obtained by the above-mentioned carbonization reaction.

[0068] Specifically, in the same fiber layer, the short fiber filaments 1 overlap each other to form a mesh overlapping structure, wherein the short fiber filaments 1 are randomly arranged in the fiber layer with good dispersion, and can form a large number of gaps by overlapping each other, so that the silicon carbide matrix 2 and the carbon matrix 3 are filled in the gaps with good distribution uniformity; in addition, in some exemplary embodiments, in the overall stacking structure formed by multiple fiber layers, the short fiber filaments 1 in two adjacent fiber layers can also overlap each other, so that overlapping disordered stacking layers are formed inside the carbon / carbon-silicon carbide composite material, which can enhance the dispersion uniformity of the silicon carbide matrix 2 and the carbon matrix 3 in the gaps between the short fiber filaments 1, and is beneficial to improving the structural strength and mechanical properties of the carbon / carbon-silicon carbide composite material.

[0069] Specifically, the length of the short fiber filaments 1 is 20 mm to 70 mm; it can be understood that the length of the short fiber filaments 1 can be any point value between 20 mm and 70 mm; illustratively, the length of the short fiber filaments 1 can be 20 mm, 25 mm, 30 mm, 40 mm, 50 mm, 55 mm, 60 mm, 70 mm, etc.; within this length range, compared with the large carbon fiber tows in the traditional process, the short fiber filaments 1 are dispersed into loosely overlapped small meshes, and the short fiber filaments 1 themselves are in the shape of fine filaments and relatively small in size, which facilitates the silicon carbide matrix 2 and the carbon matrix 3 to be filled into the gaps between the short fiber filaments 1, while forming a good fiber / matrix interface and improving the distribution uniformity of the carbon matrix 3 and the silicon carbide matrix 2; more importantly, within this length range, the short fiber filaments 1 can also maintain a certain continuity to enhance the reinforcing effect of the short fiber filaments 1 on the overall structure of the carbon / carbon-silicon carbide composite material, which is beneficial to improving the mechanical properties of the carbon / carbon-silicon carbide composite material.

[0070] Specifically, if Figure 1 As shown, the longitudinal length of the carbon fiber rod 4 is greater than the total thickness of the multiple stacked fiber layers, that is, the carbon fiber rod 4 can continuously penetrate the multiple fiber layers longitudinally, which can greatly improve the interlayer bonding strength and overall mechanical properties of the carbon / carbon-silicon carbide composite material.

[0071] Specifically, the diameter of the carbon fiber rod 4 is 0.22mm~2mm; it can be understood that the diameter of the carbon fiber rod 4 can be any point value between 0.22mm and 2mm; exemplarily, the diameter of the carbon fiber rod 4 can be 0.22mm, 0.25mm, 0.3mm, 0.5mm, 0.7mm, 1mm, 1.5mm, 2mm, etc.; within this diameter range, the diameter of the carbon fiber rod 4 is relatively thin, and it occupies a small space in the carbon / carbon-silicon carbide composite material, while being able to provide good longitudinal structural strength, greatly improving the interlayer bonding strength and comprehensive mechanical properties of the carbon / carbon-silicon carbide composite material; in addition, in some exemplary embodiments, the carbon fiber rod 4 is a pultruded carbon fiber rod 4 with thermoplastic phenolic resin as the matrix, which has high structural strength and good reliability and can effectively enhance the interlayer bonding strength.

[0072] Specifically, if Figure 1 As shown, on the same fiber layer, that is, in the transverse direction, multiple carbon fiber rods 4 are arranged in a grid shape, or multiple carbon fiber rods 4 are arranged in an array to form a grid structure, which can enhance the interlayer bonding strength in the entire transverse direction, improve the uniformity and reliability of the interlayer bonding strength in the carbon / carbon-silicon carbide composite material, prevent local delamination or fracture, and improve the overall mechanical properties of the carbon / carbon-silicon carbide composite material.

[0073] Specifically, on the same edge of the fiber layer, the lateral span between two adjacent carbon fiber rods 4 is 10mm to 100mm; it can be understood that the lateral span between two adjacent carbon fiber rods 4 can be any point value between 10mm and 100mm; illustratively, the lateral span between two adjacent carbon fiber rods 4 can be 10mm, 20mm, 25mm, 50mm, 75mm, 80mm, 100mm, etc.; within this lateral span range, it can provide sufficient and uniform interlayer bonding strength, effectively improve the mechanical properties of carbon / carbon-silicon carbide composite materials, and save carbon fiber rods 4, improve the utilization rate of carbon fiber rods 4, and save costs.

[0074] In some exemplary embodiments, with the plane direction of the fiber layer surface as the transverse direction (including the intersecting X and Y directions), and the direction perpendicular to the fiber layer surface as the longitudinal direction (or Z direction), the structure of the carbon / carbon-silicon carbide composite material is that the fine short fiber filaments 1 randomly arranged in the transverse direction overlap each other to form a mesh overlapping structure; in the longitudinal direction, multiple fiber layers are stacked to form a stacked structure, and the carbon fiber rods 4 continuously penetrate the total thickness of the multiple fiber layers longitudinally. In the entire plane of the fiber layer, multiple carbon fiber rods 4 are arranged into a transverse grid structure, and the gaps in the carbon / carbon-silicon carbide composite material are evenly filled with silicon carbide matrix 2 and carbon matrix 3, so that the carbon / carbon-silicon carbide composite material has good uniformity, interlayer bonding strength and excellent mechanical properties.

[0075] Specifically, the density of the carbon / carbon-silicon carbide composite material is greater than or equal to a preset density, which is 1.8 g / cm 3 ~2.5g / cm 3 ; It can be understood that the preset density can be 1.8g / cm 3 ~2.5g / cm 3 For example, the preset density can be 1.8 g / cm 3 , 2.0g / cm 3 , 2.1g / cm 3 , 2.2g / cm 3 , 2.3g / cm 3 , 2.4g / cm 3 , 2.5g / cm 3 etc. Within this density range, the flexural strength and interlaminar shear strength can be effectively improved, which is beneficial to improving the mechanical properties of the carbon / carbon-silicon carbide composite material; for example, in some specific embodiments, the preset density is 2.0 g / cm 3 , that is, the density of the carbon / carbon-silicon carbide composite material is greater than or equal to 2.0g / cm 3 .

[0076] Specifically, the flexural strength of the carbon / carbon-silicon carbide composite material is greater than or equal to a preset flexural strength, and the preset flexural strength is 250 MPa to 300 MPa; it can be understood that the preset flexural strength can be any point value between 250 MPa and 300 MPa; illustratively, the preset flexural strength can be 250 MPa, 255 MPa, 260 MPa, 270 MPa, 275 MPa, 280 MPa, 290 MPa, 300 MPa, etc.; for example, in some specific embodiments, the preset flexural strength is 280 MPa, that is, the flexural strength of the carbon / carbon-silicon carbide composite material is greater than or equal to 280 MPa; in this way, the carbon / carbon-silicon carbide composite material can have good mechanical properties.

[0077] Specifically, the interlaminar shear strength of the carbon / carbon-silicon carbide composite material is greater than or equal to the preset interlaminar shear strength, and the preset interlaminar shear strength is 15 MPa to 25 MPa; it can be understood that the preset interlaminar shear strength can be any point value between 15 MPa and 25 MPa; illustratively, the preset interlaminar shear strength can be 15 MPa, 16 MPa, 17 MPa, 17.5 MPa, 20 MPa, 25 MPa, etc.; for example, in some specific embodiments, the preset interlaminar shear strength is 20 MPa, that is, the interlaminar shear strength of the carbon / carbon-silicon carbide composite material is greater than or equal to 20 MPa; in this way, the carbon / carbon-silicon carbide composite material can have good mechanical properties.

[0078] The following is in conjunction with the instructions Figure 2-Figure 5The preparation method of the carbon / carbon-silicon carbide composite material of the embodiment of the present application is introduced in detail.

[0079] First, if Figure 2 As shown, short fiber filaments and modified silicon carbide are dispersed in deionized water to obtain a mixed solution.

[0080] Among them, the short fiber filaments are small meshes that are loosely overlapped and randomly arranged. In the mixed solution, the modified silicon carbide and the short fiber filaments can be effectively dispersed and overlapped with each other, so that the modified silicon carbide as the silicon carbide matrix can be evenly filled in the gaps between the short fiber filaments, thereby improving the distribution uniformity of the silicon carbide matrix. It is also beneficial to improve the distribution uniformity of the subsequent carbon matrix in the gaps between the short fiber filaments, forming a good fiber / matrix interface and improving the mechanical properties of the carbon / carbon-silicon carbide composite materials.

[0081] Specifically, in some exemplary embodiments, Figure 3 As shown, the short fiber yarn is prepared by the following steps:

[0082] heat-treating the carbon fiber bundle to obtain desized carbon fiber;

[0083] The desized carbon fibers are dispersed by air flow to obtain the short fiber filaments.

[0084] Among them, the heat treatment is used to desize the surface of the carbon fiber bundle, remove the sizing agent on the surface of the carbon fiber bundle, and then disperse the desized carbon fibers into loosely overlapped and disordered small meshes through airflow dispersion, so that the gaps in the carbon fiber bundle that were originally difficult to fill by liquid phase impregnation can be filled with the carbon matrix and the silicon carbide matrix, thereby forming a good fiber / matrix interface while improving the distribution uniformity of the carbon matrix and the silicon carbide matrix, and improving the mechanical properties of the carbon / carbon-silicon carbide composite material; in addition, in some exemplary embodiments, the carbon fiber bundle can also be pre-dispersed by short cutting before heat treatment.

[0085] In some exemplary embodiments, the heat treatment atmosphere is an oxygen-free atmosphere, the temperature is 600°C to 1500°C, and the holding time is 1h to 5h; it can be understood that the temperature can be any point value between 600°C and 1500°C, and the holding time can be any point value between 1h and 5h; exemplarily, the temperature can be 600°C, 700°C, 800°C, 1000°C, 1250°C, 1500°C, etc., and the holding time can be 1h, 2h, 2.5h, 3h, 4h, 5h, etc.; within the range of heat treatment temperature and holding time, the carbon fiber bundles can be quickly and effectively broken up into disordered fine, filamentous short fiber filaments, with high dispersion efficiency and good dispersion effect.

[0086] Specifically, if Figure 4As shown, before dispersing the short fiber filaments and modified silicon carbide in deionized water to obtain a mixed solution, the method further includes:

[0087] Silicon carbide powder is modified by hydrolyzing a solution to obtain modified silicon carbide.

[0088] The hydrolysis solution includes a precursor of silica sol, which can undergo a condensation reaction on the surface of silicon carbide powder to form a silicon dioxide layer. The surface of the silicon carbide powder in the modified silicon carbide is covered with a silicon dioxide layer. In this way, in the subsequent post-processing process, siliconization treatment will be carried out, so that the silicon dioxide layer covering the surface reacts with part of the carbon matrix to form a silicon carbide layer, thereby improving the addition efficiency of the silicon carbide matrix, reducing costs, and greatly improving the interface bonding strength between the silicon carbide matrix and the carbon matrix. At the same time, compared with traditional processes, it avoids fiber damage and silicon residue under the high-temperature reaction of molten silicon infiltration, which is beneficial to improving the purity and mechanical properties of carbon / carbon-silicon carbide composite materials.

[0089] Specifically, the precursor of the silica sol includes at least one of tetraethyl orthosilicate (TEOS), trimethylethoxysilane (TMES), methyltrimethoxysilane (MTMS), dimethyldiethoxysilane (DDS) and sodium silicate, which can effectively modify the silicon carbide powder to form a silicon dioxide layer, thereby helping to improve the addition efficiency of the silicon carbide matrix and its interfacial bonding strength with the carbon matrix, thereby improving the mechanical properties of the carbon / carbon-silicon carbide composite material.

[0090] In some exemplary embodiments, the hydrolysis solution further includes a catalyst and a solvent, wherein the solvent may be a mixed solvent of ethanol and deionized water, and the catalyst may be an acid catalyst, which can effectively catalyze the reaction so that the precursor of the silica sol undergoes a condensation reaction on the surface of silicon carbide.

[0091] In some exemplary embodiments, the modification temperature is 60°C to 80°C, and the time is 2h to 4h; it can be understood that the modification temperature can be any point value between 60°C and 80°C, and the time can be any point value between 2h and 4h; illustratively, the modification temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, etc., and the time can be 2h, 2.5h, 3h, 3.5h, 4h, etc.; within the modification temperature and time range, the condensation reaction can be carried out efficiently and stably, thereby improving the effectiveness and reliability of the silicon dioxide layer covering the surface of the silicon carbide powder, which is beneficial to ultimately improve the mechanical properties of the carbon / carbon-silicon carbide composite material.

[0092] After the condensation reaction, the modified silicon carbide powder is washed with ethanol and dried to obtain modified silicon carbide, which is silicon carbide with a silicon dioxide layer on the surface. The drying temperature is 80°C to 100°C, and the time is 2h to 4h. It can be understood that the drying temperature can be any point value between 80°C and 100°C, and the time can be any point value between 2h and 4h. For example, the drying temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, etc., and the time can be 2h, 2.5h, 3h, 3.5h, 4h, etc. Within the drying temperature and time range, the purity of the modified silicon carbide can be improved, which is beneficial to the stable progress of subsequent processes, reducing the impurity content in the final carbon / carbon-silicon carbide composite material, improving the purity, and benefiting the improvement of mechanical properties.

[0093] Specifically, in the mixed solution, the mass ratio of the staple fiber filaments to deionized water is 1:10 to 1:100; it can be understood that the mass ratio of the staple fiber filaments to deionized water can be any ratio between 1:10 and 1:100; illustratively, the mass ratio of the staple fiber filaments to deionized water can be 1:10, 1:20, 1:25, 1:30, 1:50, 1:75, 1:100, etc.; within this mass ratio range, the staple fiber filaments have good dispersibility, which is convenient for mixing with modified silicon carbide, thereby improving the uniformity of dispersion of modified silicon carbide among the staple fiber filaments.

[0094] Specifically, in the mixed solution, the mass ratio of the short fiber filaments to the modified silicon carbide is 2:1 to 15:1; it can be understood that the mass ratio of the short fiber filaments to the modified silicon carbide can be any point value between 2:1 and 15:1; illustratively, the mass ratio of the short fiber filaments to the modified silicon carbide can be 2:1, 5:1, 7.5:1, 10:1, 12:1, 15:1, etc.; within this mass ratio range, the short fiber filaments and the modified silicon carbide can overlap with each other, which is convenient for improving the bonding reliability of the fiber / silicon carbide matrix interface, and also convenient for improving the distribution uniformity of the modified silicon carbide and the final silicon carbide matrix.

[0095] Specifically, in some exemplary embodiments, in the mixed solution, the modified silicon carbide also includes one or more of silicon ceramic powder and silicon nitride ceramic powder, and the particle size of the silicon ceramic powder and the silicon nitride ceramic powder is less than or equal to 50 μm, which can provide a silicon source for the subsequent silicidation reaction to a certain extent, improve the addition efficiency of silicon carbide, and help improve the mechanical properties of the carbon / carbon-silicon carbide composite material.

[0096] Specifically, in some exemplary embodiments, the mixed solution also includes a dispersant, which includes one or more of hydroxypropyl methylcellulose, hydroxyethyl methylcellulose and polyethylene glycol, and has good dispersibility, which is beneficial to improving the dispersion efficiency and uniformity of the short fiber filaments and modified silicon carbide.

[0097] Specifically, in the mixed solution, the mass ratio of the dispersant to deionized water is 1:50 to 1:250; it can be understood that the mass ratio of the dispersant to deionized water can be any point value between 1:50 and 1:250; for example, the mass ratio of the dispersant to deionized water can be 1:50, 1:75, 1:100, 1:150, 1:200, 1:250, etc.; within this mass ratio range, the amount of dispersant added is small, the utilization rate is high, and the dispersibility of the short fiber filaments and modified silicon carbide is good, which is beneficial to improving the subsequent dispersion uniformity of the short fiber filaments, silicon carbide matrix and carbon matrix in the fiber layer.

[0098] Next, the mixed solution is placed in a filter tank for suction filtration, so that the mixed solution forms a plurality of stacked fiber layers to obtain a prefabricated structure.

[0099] During the filtration process, the short fiber filaments and modified silicon carbide in the mixed solution are integrally formed to form multiple stacked fiber layers, which simplifies the production process and reduces the process cycle and cost; and, a plurality of carbon fiber rods are provided in the filter tank, and the plurality of carbon fiber rods are arranged in a grid array. In some exemplary embodiments, the plurality of carbon fiber rods can be fixedly connected to the top of the filter tank by fixing the top end, and a filtration hole is provided at the bottom of the filter tank, and the filtration hole has a mesh steel plate base, and a 50-300 mesh mesh is laid on the base to filter the mixed solution, forming a flat mesh fiber layer stack in the filter tank, and the gaps are evenly filled with modified silicon carbide, and the carbon fiber rods are longitudinally interspersed in the prefabricated structure of the multiple stacked fiber layers, which greatly improves the interlayer bonding strength between the fiber layers in the final carbon / carbon-silicon carbide composite material and the overall mechanical properties of the carbon / carbon-silicon carbide composite material.

[0100] Next, the prefabricated structure is immersed in a resin solution, filtered and dried to obtain a prepreg.

[0101] The resin solution includes a phenolic resin, which can serve as at least a partial carbon source of the carbon matrix in the final carbon / carbon-silicon carbide composite material. During the formation of the prepreg, the phenolic resin in the resin solution can be uniformly dispersed in the gaps between the short fiber filaments. Specifically, in some exemplary embodiments, in the resin solution, the phenolic resin includes one or more of PF8402, PF8218, PF9501, and boron phenolic modified resin.

[0102] Specifically, the resin solution also includes a silane coupling agent. The silicon dioxide layer in the modified silicon carbide can be chemically bridged with the phenolic resin through the silane coupling agent, so that the modified silicon carbide can be well combined with the phenolic resin, which facilitates the subsequent short-cycle silicification reaction to convert the surface silicon dioxide into a thin silicon carbide layer by reacting with part of the carbon matrix, that is, into part of the silicon carbide matrix, greatly improving the interface bonding strength between the silicon carbide matrix and the carbon matrix. At the same time, it also avoids fiber damage and precious residues under the high-temperature reaction of molten silicon infiltration in traditional processes, greatly reduces the impurity content, improves the purity, and is beneficial to improving the mechanical properties of the final carbon / carbon-silicon carbide composite material.

[0103] Specifically, in some exemplary embodiments, in the resin solution, the silane coupling agent includes one or more of KH-550, KH-560, and KH-792, which has a good coupling effect on the silica in the modified silicon carbide and the phenolic resin.

[0104] Specifically, the mass proportion of the silane coupling agent in the resin solution is 0.1% to 0.7%; it can be understood that the mass proportion of the silane coupling agent in the resin solution can be any point value between 0.1% and 0.7%; illustratively, the mass proportion of the silane coupling agent in the resin solution can be 0.1%, 0.2%, 0.25%, 0.3%, 0.5%, 0.6%, 0.7%, etc.; within this mass proportion range, a good chemical bridge of silica-silane coupling agent-phenolic resin can be constructed without affecting the material properties, thereby greatly improving the interfacial bonding strength of the silicon carbide matrix and the carbon matrix, avoiding fiber damage and silicon residue, and helping to improve the mechanical properties of the final carbon / carbon-silicon carbide composite material.

[0105] Specifically, the viscosity of the resin solution is 100 MPa·s to 2000 MPa·s; it can be understood that the viscosity of the resin solution can be any point value between 100 MPa·s and 2000 MPa·s; illustratively, the viscosity of the resin solution can be 100 MPa·s, 200 MPa·s, 500 MPa·s, 1000 MPa·s, 1500 MPa·s, 2000 MPa·s, etc.; within this viscosity range, the resin solution can effectively penetrate into the interior of the prefabricated structure and fully infiltrate it, thereby increasing the contact area between the phenolic resin and the short fiber filaments and modified silicon carbide, and increasing the bonding tightness between the phenolic resin and the modified silicon carbide, thereby increasing the interface bonding strength between the silicon carbide matrix and the carbon matrix, and avoiding fiber damage and silicon residue.

[0106] In addition, the resin solution includes an ethanol solvent, which has good solubility for the phenolic resin and the silane coupling agent, has a good infiltration effect on the prefabricated structure, and is also easy to remove during the drying process.

[0107] In some exemplary embodiments, after the prefabricated structure is impregnated in the resin solution and filtered, the drying temperature is 60°C to 90°C, and the time is 1h to 5h; it can be understood that the drying temperature can be any point value between 60°C and 90°C, and the time can be any point value between 1h and 5h; exemplarily, the drying temperature can be 60°C, 70°C, 75°C, 80°C, 90°C, etc.; the time can be 1h, 1.5h, 2h, 3h, 4h, 5h, etc.; within this drying temperature and time range, the solvent can be effectively removed to form a fiber-powder prepreg.

[0108] Specifically, in some exemplary embodiments, after obtaining the prefabricated structure and before infiltrating the prefabricated structure into the resin solution, the method further comprises:

[0109] filtering the prefabricated structure through an ethanol solution to remove moisture from the prefabricated structure, thereby obtaining a prefabricated structure after dehydration;

[0110] Accordingly, the prefabricated structure is soaked in a resin solution, filtered and dried to obtain a prepreg, which includes:

[0111] The prefabricated structure after dehydration is immersed in the resin solution, filtered and dried to obtain the prepreg.

[0112] Among them, the excess ethanol solution can effectively remove the residual moisture in the prefabricated structure, prevent the generation of additional impurities in the subsequent infiltration and post-processing processes, and also facilitate the removal of ethanol solvent during the drying process, which is beneficial to improving the purity and mechanical properties of carbon / carbon-silicon carbide composite materials.

[0113] Specifically, after obtaining the prepreg and before subsequently post-processing the prepreg to obtain the carbon / carbon-silicon carbide composite material, the method further includes:

[0114] The prepreg is subjected to a curing treatment.

[0115] The curing treatment is used to cure and mold the fiber-powder prepreg to form a preliminary cured structure of a carbon / carbon-silicon carbide composite material in which multiple fiber layers are stacked and multiple carbon fiber rods are longitudinally interspersed, with good molding effect; the curing treatment can be carried out by hot pressing curing, with a curing temperature of 180°C to 300°C, a holding time of 2h to 5h, a variable hydraulic pressure, and a hydraulic pressure of 1MPa to 12MPa; it can be understood that the curing temperature can be any point value between 180°C and 300°C, the holding time can be any point value between 2h to 5h, the hydraulic pressure can be a variable hydraulic pressure, and the hydraulic pressure can be any point value between 1MPa and 12MPa, which are not enumerated here; for example, in an exemplary specific embodiment, the curing treatment temperature is 200°C, the holding time is 3h, and the hydraulic pressure is gradually increased from 1MPa to 12MPa and maintained.

[0116] Next, the prepreg is post-processed to obtain a carbon / carbon-silicon carbide composite material.

[0117] Specifically, if Figure 5 As shown, in the post-processing process, the method further includes:

[0118] performing a carbonization treatment on the prepreg so that the phenolic resin forms a carbon matrix to obtain a carbonized body;

[0119] The carburized body is subjected to a silicidation treatment so that the silicon dioxide layer and at least a portion of the carbon matrix undergo a silicidation reaction to generate silicon carbide, thereby obtaining the carbon / carbon-silicon carbide composite material.

[0120] During the post-processing process, the phenolic resin in the prepreg is converted into a carbon matrix, and the modified silicon carbide is converted into a silicon carbide matrix; that is, in the carbon / carbon-silicon carbide composite material, at least a portion of the carbon matrix in the carbon matrix distributed in the gaps between the short fiber filaments is converted based on the phenolic resin, and in the carbonized blank that has undergone carbonization treatment, part of the carbon matrix can further undergo a slight silicidation reaction with the silicon dioxide on the surface of the modified silicon carbide, so that the silicon dioxide is consumed to generate a silicon carbide matrix, that is, at least a portion of the silicon carbide matrix distributed in the gaps between the short fiber filaments is generated based on the silicidation reaction, which can increase the addition efficiency of the silicon carbide matrix, reduce costs, and greatly improve the interface bonding strength between the silicon carbide matrix and the carbon matrix, while reducing the impurity content, avoiding fiber damage and silicon residue, and improving purity, which is beneficial to improving the mechanical properties of the carbon / carbon-silicon carbide composite material.

[0121] Among them, the temperature of the carbonization treatment is 650°C to 950°C; it can be understood that the temperature of the carbonization treatment can be any point value between 650°C and 950°C; illustratively, the temperature of the carbonization treatment can be 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, etc.; within this carbonization treatment temperature range, the phenolic resin can be effectively converted into a carbon matrix, thereby improving the interfacial bonding strength of the carbon matrix, and providing good support for the subsequent silicidation reaction, thereby improving the interfacial bonding strength of the silicon carbide matrix, improving the addition efficiency of the silicon carbide matrix, and reducing costs.

[0122] Specifically, the post-processing also includes a densification treatment, in which a carbon matrix is ​​added to the carbonized body. The carbon matrix added during the densification treatment serves as a part of the carbon matrix in the final carbon / carbon-silicon carbide composite material, so that the density of the carbonized body after the densification treatment can be greater than or equal to the preset density. The densification treatment includes at least one of vapor deposition densification and liquid phase densification; wherein, in the process of densification by vapor deposition, the carbon matrix added by the densification treatment includes at least one of carbon sources such as natural gas and methane; in the process of densification by liquid phase, the carbon matrix added by the densification treatment includes at least one of carbon sources such as phenolic resin, furan resin and asphalt; the densification treatment can effectively increase the density of the carbon / carbon-silicon carbide composite material, which is beneficial to improving the bending strength and interlaminar shear strength of the carbon / carbon-silicon carbide composite material.

[0123] In some optional embodiments, the densification treatment may be performed after the carbonization treatment and before the siliconization treatment, that is, the method for preparing the carbon / carbon-silicon carbide composite material further includes:

[0124] performing a densification treatment on the carbonized body to obtain a densified carbonized body;

[0125] The densified carburized body is subjected to siliconization treatment to obtain the carbon / carbon-silicon carbide composite material.

[0126] In some other optional embodiments, the densification treatment may be performed after the siliconization treatment, that is, the method for preparing the carbon / carbon-silicon carbide composite material further comprises:

[0127] The carbonized blank after the siliconization treatment is subjected to a densification treatment to obtain the carbon / carbon-silicon carbide composite material.

[0128] Specifically, in some exemplary embodiments, the post-treatment further includes a purification treatment to effectively reduce the ash impurities in the carbon / carbon-silicon carbide composite material and improve the purity, which is beneficial to improving the mechanical properties of the carbon / carbon-silicon carbide composite material.

[0129] The temperature of the purification treatment is 1800°C to 2400°C; it can be understood that the temperature of the purification treatment can be any point value between 1800°C and 2400°C; illustratively, the temperature of the purification treatment can be 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, etc.; within this purification treatment temperature range, the ash impurities are removed efficiently and at a high removal rate, which can greatly improve the purity of the carbon / carbon-silicon carbide composite material.

[0130] In some optional embodiments, the purification treatment may be performed after the silicidation treatment, that is, the carbide blank is subjected to silicidation treatment so that the silicon dioxide layer and at least a portion of the carbon matrix undergo a silicidation reaction to generate silicon carbide, and the carbon / carbon-silicon carbide composite material is obtained, which comprises:

[0131] performing a silicidation treatment on the carbide blank so that the silicon dioxide layer and at least a portion of the carbon matrix undergo a silicidation reaction to generate silicon carbide, thereby obtaining a silicidated blank;

[0132] The silicided body is purified to obtain the carbon / carbon-silicon carbide composite material.

[0133] In other exemplary embodiments, the purification treatment may be combined with the siliconization treatment, that is, the carbonized body is subjected to siliconization treatment so that the silicon dioxide layer reacts with at least a portion of the carbon matrix to form silicon carbide, thereby obtaining the carbon / carbon-silicon carbide composite material, which comprises:

[0134] The carburized body is subjected to siliconization and purification treatments so that the silicon dioxide layer undergoes a siliconization reaction with at least a portion of the carbon matrix to generate silicon carbide, thereby obtaining the carbon / carbon-silicon carbide composite material.

[0135] Specifically, before finally obtaining the carbon / carbon-silicon carbide composite material, the method further comprises:

[0136] The carbonized blank after siliconization treatment is machined to obtain the carbon / carbon-silicon carbide composite material.

[0137] This machining process is the last process, which is performed after the densification process, the siliconization process, and the purification process, so that the carbon / carbon-silicon carbide composite material becomes a composite material with desired dimensions.

[0138] The preparation method of the carbon / carbon-silicon carbide composite material has a short preparation cycle, low cost, and little damage to the fibers of the short fiber filaments and carbon fiber rods, which is beneficial to improving the comprehensive performance of the carbon / carbon-silicon carbide composite material; wherein, the modified silicon carbide, short fiber filaments and carbon fiber rods are mixed and molded into an integrated body, which simplifies the preparation process, shortens the preparation cycle, and reduces the preparation cost, and uses short fiber filaments that have been pre-treated by chopped and dispersed into a layer of fine filaments, which are mixed with modified silicon carbide by deionized water and dispersed into mutually overlapping disordered stacked layers, which greatly improves the separation of the short fiber filaments and the subsequent silicon carbide matrix. Compared with the traditional process, the short fiber filaments are loosely overlapped into a small mesh, which makes it possible to fill the gaps in the carbon fiber tows that were originally difficult to fill with liquid phase impregnation into the carbon matrix and the silicon carbide matrix, forming a good fiber / matrix interface while making the carbon matrix and the silicon carbide matrix more evenly distributed, thereby improving the mechanical properties of the carbon / carbon-silicon carbide composite material; in addition, the introduction of vertically inserted carbon fiber rods into the well-dispersed short fiber filaments and modified silicon carbide, that is, the introduction of a large number of through-type reinforcing fibers, can greatly improve the interlayer bonding strength and mechanical properties of the carbon / carbon-silicon carbide composite material.

[0139] Furthermore, the silicon carbide powder is modified by a hydrolysis solution of a precursor having a silica sol, so that the surface is covered with a silicon dioxide layer. After being soaked in a resin solution, a "silicon dioxide-coupling agent-resin" chemical bridge can be constructed through the silane coupling agent in the resin solution, so that the modified silicon carbide can be well combined with the phenolic resin. The modified silicon carbide can undergo an ultra-short cycle micro-siliconization reaction in the subsequent siliconization treatment process, and the surface silicon dioxide reacts with part of the carbon matrix to convert it into a thin silicon carbide layer, which greatly improves the addition efficiency of the silicon carbide matrix, reduces costs, and greatly improves the interface bonding between the silicon carbide matrix and the carbon matrix. At the same time, it avoids fiber damage and silicon residue under the high-temperature reaction of molten silicon infiltration, effectively improving the purity and mechanical properties of the carbon / carbon-silicon carbide composite material.

[0140] The following describes the embodiments of the present application in combination with the above technical solutions.

[0141] The carbon / carbon-silicon carbide composite materials in Examples 1-8 were prepared by the following steps:

[0142] 1. Heat-treating the carbon fiber bundle at 600°C to 1500°C for 1h to 5h to obtain desizing carbon fiber, and air-dispersing the desizing carbon fiber to obtain short fiber filaments with a length of 20mm to 70mm and in the form of fine filaments;

[0143] 2. Modifying silicon carbide powder with a hydrolysis solution containing a silica sol precursor at 60° C. to 80° C. for 2 h to 4 h, washing with ethanol, and then drying at 80° C. to 100° C. for 2 h to 4 h to obtain modified silicon carbide with a silicon dioxide layer covering the surface of the silicon carbide powder; the hydrolysis solution also includes a small amount of acid as a catalyst and a mixed solvent of ethanol and deionized water;

[0144] 3. Dispersing the airflow-dispersed short fiber filaments, modified silicon carbide, and dispersant in deionized water according to a preset mass ratio of the short fiber filaments, modified silicon carbide, dispersant, and deionized water to obtain a mixed solution;

[0145] 4. Placing the mixed solution in a filter tank with multiple carbon fiber rods and filtering the bottom to form multiple stacked fiber layers to obtain a prefabricated structure; the filter tank has a filtration hole at the bottom, a mesh steel plate base on which is laid a 50-300 mesh mesh, and a certain number of pultruded carbon fiber rods based on thermoplastic phenolic resin are fixed and inserted at the top. The diameter of the carbon fiber rods is 0.2 mm to 2.0 mm, and the carbon fiber rods are arranged in a grid with a side length of 10 mm to 100 mm; in the prefabricated structure, the stacked planar mesh fiber layers are evenly filled with modified silicon carbide, and the carbon fiber rods are longitudinally interspersed in the multiple stacked fiber layers;

[0146] 5. Filtering the prefabricated structure through an ethanol solution to remove moisture from the prefabricated structure to obtain a dehydrated prefabricated structure;

[0147] 6. Immerse the prefabricated structure after dehydration in a resin solution, filter it, and dry it at 60° C. to 90° C. for 1 hour to 5 hours to obtain a prepreg; the resin solution includes a phenolic resin, a silane coupling agent, and an ethanol solvent, the mass ratio of the silane coupling agent in the resin solution is wt, and the viscosity of the resin solution is η;

[0148] 7. Curing the prepreg at 150°C to 200°C for 2 to 4 hours, gradually increasing the hydraulic pressure from 1 MPa to 12 MPa and maintaining the pressure to obtain a cured prepreg;

[0149] 8. Carbonizing the cured prepreg at 650° C. to 950° C. to form a carbon matrix from the phenolic resin, thereby obtaining a carbonized body;

[0150] 9. Performing a densification treatment on the carbonized body to obtain a carbonized body with a preset density ρ;

[0151] 10. Performing a silicidation treatment on the densified carbide body and a purification treatment at 1800° C. to 2400° C. to cause the silicon dioxide layer to react with at least a portion of the carbon matrix to form silicon carbide and reduce the ash impurities in the material;

[0152] 11. The carbonized blank after siliconization and purification treatment is machined to obtain a carbon / carbon-silicon carbide composite material; wherein the carbon fiber rods are longitudinally interspersed in a plurality of stacked fiber layers, the fiber layers include short fiber filaments, a silicon carbide matrix and a carbon matrix, and the silicon carbide matrix and the carbon matrix are distributed in the gaps between the short fiber filaments.

[0153] The test conditions and test results of each embodiment are shown in Table 1 below.

[0154] Table 1 Test results of carbon / carbon-silicon carbide composite materials of Examples 1-8

[0155]

[0156] Comparative Example

[0157] Conventional carbon / carbon-silicon carbide composite materials are prepared by the following steps:

[0158] 1. Preparation of carbon fiber preform: 2.5D carbon fiber needle-punched preform was prepared by alternately laying 12K-T700 polyacrylonitrile-based carbon fiber free-weft cloth and chopped carbon fiber carded web and Z-direction needle-punching. The free-weft cloth was laid alternately at 0° and 90°.

[0159] 2. Preparation of carbon / carbon composite body: The carbon fiber preform is placed in an isothermal chemical vapor deposition infiltration furnace. Natural gas is used as the precursor and nitrogen is used as the carrier gas. Under the condition of 900℃~1100℃, the natural gas is cracked to produce a pyrolytic carbon matrix which infiltrates into the pores of the carbon fiber preform to obtain a carbon / carbon composite body with a density of 1.3g / cm 3 ~1.5g / cm 3 .

[0160] 3. Siliconization treatment: Place the carbon / carbon composite body in a graphite crucible filled with silicon powder and compact the silicon powder; then place the crucible in a vacuum furnace, heat it to 1420℃~1800℃, and keep it warm for 1h~3h. Through the reaction infiltration process, silicon and pyrolytic carbon react to form silicon carbide, forming a siliconized carbon / carbon-silicon carbide composite body with a volume density of 2.24g / cm 3 .

[0161] 4. The carbon / carbon-silicon carbide composite material blank after siliconization is purified at 1800°C to 2400°C to reduce the ash impurities in the material.

[0162] 5. Machining the purified carbon / carbon-silicon carbide composite material blank to obtain a carbon / carbon-silicon carbide composite material.

[0163] Mechanical properties tests were performed on the carbon / carbon-silicon carbide composite material prepared by conventional processes in this comparative example, and the measured flexural strength was 130.6 MPa and the interlaminar shear strength was 20.1 MPa.

[0164] Referring to the test results in Table 1 and comparing with the comparative examples, it can be seen that the density of the carbon / carbon-silicon carbide composite materials prepared in Examples 1-8 is all within 2.0 g / cm 3 The above is higher than the density of the carbon / carbon-silicon carbide composite material in the comparative example, which is beneficial to improving the mechanical properties of the carbon / carbon-silicon carbide composite material; moreover, the flexural strength in each embodiment is above 260 MPa, which is much higher than the flexural strength of the conventional carbon / carbon-silicon carbide composite material in the comparative example, and has good flexural resistance and toughness, which is beneficial to improving the durability of the carbon / carbon-silicon carbide composite material; and the interlaminar shear strength of the carbon / carbon-silicon carbide composite materials prepared in Examples 1-8 are also above 18 MPa, especially in Examples 1-5, the interlaminar shear strength reaches 21.4 MPa and above, with good anti-cracking performance, indicating that the carbon / carbon-silicon carbide composite material prepared by this preparation method has strong interlaminar bonding strength and comprehensive mechanical properties.

[0165] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0166] What is described above are only some embodiments of the present application and are not intended to limit the present application. Those skilled in the art should understand that the present application may be subject to various changes and improvements, and any modifications, equivalent substitutions, and improvements made in accordance with the present application shall fall within the scope of protection required by the present application.

Claims

1. A method for preparing a carbon / carbon-silicon carbide composite material, characterized in that: include: Dispersing short fiber filaments and modified silicon carbide in deionized water to obtain a mixed solution; The surface of the silicon carbide powder in the modified silicon carbide is covered with a silicon dioxide layer; The mixed solution is placed in a filter tank for suction filtration, so that the mixed solution forms multiple stacked fiber layers to obtain a prefabricated structure; a plurality of carbon fiber rods are provided in the filter tank; in the prefabricated structure, the carbon fiber rods are longitudinally interspersed with the multiple stacked fiber layers; The prefabricated structure is immersed in a resin solution, filtered and dried to obtain a prepreg; the resin solution includes phenolic resin; post-processing the prepreg to obtain a carbon / carbon-silicon carbide composite material; During the post-treatment process, the phenolic resin is converted into a carbon matrix, and the modified silicon carbide is converted into a silicon carbide matrix; in the fiber layer of the carbon / carbon-silicon carbide composite material, the carbon matrix and the silicon carbide matrix are distributed in the gaps between the short fiber filaments.

2. The method for preparing the carbon / carbon-silicon carbide composite material according to claim 1, characterized in that: The short fiber filaments are prepared by the following steps: heat-treating the carbon fiber bundle to obtain desized carbon fiber; The desized carbon fibers are dispersed by air flow to obtain the short fiber filaments; the length of the short fiber filaments is 20 mm to 70 mm.

3. The method for preparing the carbon / carbon-silicon carbide composite material according to claim 1, characterized in that: Before dispersing the short fiber filaments and modified silicon carbide in deionized water to obtain a mixed solution, the method further includes: Silicon carbide powder is modified by a hydrolysis solution to obtain modified silicon carbide; the hydrolysis solution includes a precursor of a silica sol, and the precursor of the silica sol includes at least one of ethyl orthosilicate, trimethylethoxysilane, methyltrimethoxysilane, dimethyldiethoxysilane and sodium silicate. The precursor of the silica sol undergoes a condensation reaction on the surface of the silicon carbide to form the silicon dioxide layer.

4. The method for preparing the carbon / carbon-silicon carbide composite material according to claim 3, characterized in that: The mixed solution satisfies at least one of the following characteristics: The mass ratio of the short fiber filaments to the deionized water is 1:10 to 1:100; The mass ratio of the short fiber filaments to the modified silicon carbide is 2:1 to 15:1; The modified silicon carbide further comprises one or more of silicon ceramic powder and silicon nitride ceramic powder, and the particle size of the silicon ceramic powder and the silicon nitride ceramic powder is less than or equal to 50 μm; The mixed solution further comprises a dispersant, which comprises one or more of hydroxypropyl methylcellulose, hydroxyethyl methylcellulose and polyethylene glycol; The mass ratio of the dispersant to the deionized water is 1:50 to 1:

250.

5. The method for preparing the carbon / carbon-silicon carbide composite material according to claim 3, characterized in that: The resin solution satisfies at least one of the following characteristics: The phenolic resin includes one or more of PF8402, PF8218, PF9501, and boron phenolic modified resin; The resin solution further comprises a silane coupling agent, and the silicon dioxide layer in the modified silicon carbide can be chemically bridged with the phenolic resin through the silane coupling agent; The silane coupling agent includes one or more of KH-550, KH-560, and KH-792; The mass proportion of the silane coupling agent in the resin solution is 0.1% to 0.7%; The viscosity of the resin solution is 100 mPa·s to 2000 mPa·s.

6. The method for preparing the carbon / carbon-silicon carbide composite material according to claim 3, characterized in that: During the post-processing, the method further comprises: performing a carbonization treatment on the prepreg so that the phenolic resin forms a carbon matrix to obtain a carbonized body; The carburized body is subjected to a silicidation treatment so that the silicon dioxide layer and at least a portion of the carbon matrix undergo a silicidation reaction to generate silicon carbide, thereby obtaining the carbon / carbon-silicon carbide composite material.

7. The method for preparing the carbon / carbon-silicon carbide composite material according to any one of claims 1 to 6, characterized in that: Before post-processing the prepreg to obtain the carbon / carbon-silicon carbide composite material, the method further includes: The prepreg is subjected to a curing treatment.

8. The method for preparing the carbon / carbon-silicon carbide composite material according to any one of claims 1 to 6, characterized in that: The post-treatment further includes at least one of a densification treatment and a purification treatment. The densification treatment includes at least one of vapor deposition densification and liquid phase densification. The temperature of the purification treatment is 1800°C to 2400°C.

9. A carbon / carbon-silicon carbide composite material, characterized in that: Prepared by the preparation method of the carbon / carbon-silicon carbide composite material according to any one of claims 1 to 8; the carbon / carbon-silicon carbide composite material includes a plurality of fiber layers and a plurality of carbon fiber rods stacked together, and the carbon fiber rods are longitudinally interspersed in the plurality of stacked fiber layers; the fiber layers include short fiber filaments, a silicon carbide matrix and a carbon matrix, and the silicon carbide matrix and the carbon matrix are distributed in the gaps between the short fiber filaments.

10. The carbon / carbon-silicon carbide composite material according to claim 9, characterized in that: The fiber layer satisfies at least one of the following characteristics: In the same fiber layer, the short fiber filaments are overlapped with each other to form a mesh overlap structure; The length of the short fiber filaments is 20 mm to 70 mm.

11. The carbon / carbon-silicon carbide composite material according to claim 9, characterized in that: The carbon fiber rod meets at least one of the following characteristics: The longitudinal length of the carbon fiber rod is greater than the total thickness of the multiple stacked fiber layers; The diameter of the carbon fiber rod is 0.22mm to 2mm; On the same fiber layer, a plurality of carbon fiber rods are arranged in a grid shape; On the same edge of the fiber layer, the transverse span between two adjacent carbon fiber rods is 10 mm to 100 mm.

12. The carbon / carbon-silicon carbide composite material according to any one of claims 9 to 11, characterized in that: The carbon / carbon-silicon carbide composite material satisfies at least one of the following characteristics: The density of the carbon / carbon-silicon carbide composite material is greater than or equal to 1.8 g / cm 3 ; The flexural strength of the carbon / carbon-silicon carbide composite material is greater than or equal to 250 MPa; The interlaminar shear strength of the carbon / carbon-silicon carbide composite material is greater than or equal to 15 MPa.

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