Carbon / carbon composite material, modification method and brazing method of carbon / carbon composite material and nickel-based superalloy

Abstract

The invention relates to the technical field of composite material and metal connection, in particular to a carbon / carbon composite material, a modification method and a nickel-based high-temperature alloy brazing method thereof, a SiC coating and a Mo-Si coating are sequentially embedded and sprayed on the carbon / carbon composite material, and a SiC-MoSi composite coating is formed on the surface of the carbon / carbon composite material through high-temperature heat treatment curing. Due to the existence of the SiC-MoSi composite coating, a CTE transition layer is provided for a connector, residual stress caused by thermal expansion difference is reduced, conditions for generating Mo-based compounds are created, wettability and interface bonding strength of brazing filler metal and base metal can be improved, interface reaction of the base metal can be optimized, a uniform and continuous brazing layer is formed, and the service life of the brazing filler metal is prolonged. Therefore, the brazed connection is higher in strength and more stable, and is more suitable for connection of large-size components and service under the high-temperature condition. The problems that in the prior art, the connection performance of a carbon / carbon composite material and dissimilar metal is poor, and failure is prone to occurring are solved.

Description

Technical Field

[0001] The invention relates to the technical field of composite material and metal connection, in particular to a carbon / carbon composite material, a modification method and a nickel-based high-temperature alloy brazing method thereof. Background Art

[0002] In the field of aerospace, high heat load equipment such as aircraft and satellites face extremely high heat flux density, especially satellite antennas and engine components. In order to prevent the equipment from overheating and damage, it is urgent to use high thermal conductivity materials for efficient heat dissipation to ensure its stable operation in high power density environments. The combination of carbon / carbon composites and nickel-based high-temperature alloys (GH3230) has important application prospects in the fields of aerospace, energy and high-temperature structural materials. Carbon / carbon composites are widely used in high-performance components in extreme environments due to their light weight, high specific strength, low coefficient of thermal expansion (CTE) and excellent high thermal conductivity. However, carbon / carbon composites are brittle and difficult to directly connect with metal materials. Therefore, achieving reliable connection between carbon / carbon composites and metals has always been an important research direction in the field of materials science. GH3230 is a solid solution and carbide strengthened Ni-Cr-W-Mo deformation high-temperature alloy with a service temperature range of 700℃~1100℃. The alloy has high plasticity and medium thermal strength, and has excellent oxidation resistance and good stamping and welding process performance. However, due to the high density and heavy weight of GH3230, as well as the limited operating temperature range, its application areas are limited. Connecting carbon / carbon composite materials with GH3230 alloy by brazing can not only retain the lightweight, high strength and high thermal conductivity characteristics of carbon / carbon composite materials, but also utilize the high strength and high temperature performance of nickel-based high-temperature alloys, thereby realizing the preparation of high heat flux density heat sinks.

[0003] However, the CTE difference between carbon / carbon composite materials and GH3230 alloy materials is large, and the connection between the two often causes thermal mismatch problems. Carbon / carbon composite materials have a small CTE, and cracks are easily generated at the interface between carbon / carbon and brazing filler metal due to excessive residual thermal stress. In addition, the wettability and bonding surface crack initiation problems between nickel-based brazing filler metal and carbon / carbon composite materials also need to be solved urgently. Therefore, studying the defect control of carbon / carbon-GH3230 brazed joints and increasing the wettability of the connection interface will not only help to deeply understand the key issues in the brazing process, but also promote the practical application of high-performance structural materials. By optimizing the brazing process, defects in the joint can be effectively reduced, and the mechanical properties and high-temperature stability of the joint can be improved.

[0004] The base material modification process is to treat the base material surface or the whole body so that the base material can provide better bonding strength and lower interface stress during the contact process with the brazing filler metal. Common base material surface modification methods include surface pretreatment, coating method, heat treatment method, ion beam treatment and laser surface treatment. Through surface modification, the wettability of the brazing filler metal to the base material can be significantly improved, and the bonding strength of the brazed joint can be enhanced; in addition, the intermediate layer metal or coating can also form a good metallurgical bond between the base material and the brazing filler metal. At the same time, by adjusting the thermal expansion characteristics of the base material surface and the brazing filler metal, the thermal stress of the joint can be effectively reduced, and the risk of thermal cracking can be reduced.

[0005] In the literature "Li S, Lu Q, Du D, et al. Effect of C / C composite surfacepretreatment on properties of brazed joint[J]. Welding in the World. 2022: 1-8.", Li et al. used BNi-2 brazing filler metal to achieve brazing of carbon / carbon composite material and TiAl alloy at 1030℃ / 20 min. After surface pretreatment of carbon / carbon composite material using a portable flame spray gun, the microstructure of carbon / carbon-TiAl joint is TiAl alloy→TiAl+AlNi3→AlNi2Ti→Ni ss +Ti3Al+Ni3Si→Ni ss +Ni3(Si,B)+CrB→Ni ss +Ni3Si+TiCr2→(Ti,Cr)C→carbon / carbon composite material. The average room temperature shear strength of the brazed joint after surface pretreatment is 14.8MPa, which is about 50% higher than that of the brazed joint without carbon / carbon composite material surface treatment. However, this method uses the outer flame of a neutral flame to ablate the surface of the carbon / carbon composite material for brazing for 1-3 minutes until the carbon matrix is ​​peeled off from the composite material, which will damage the carbon / carbon composite material base material and reduce the strength of the base material.

[0006] In the literature "Wang J, Jia X, Feng Y, et al. Effect of micro-oxidation and Cumodification of C / C composite on microstructure and mechanical properties ofC / C Ti3Al joints[J]. Vacuum. 2022, 203: 111255.", Wang et al. prepared a copper coating on the surface of a carbon / carbon composite by using muffle furnace micro-oxidation and magnetron sputtering in order to form a strong mechanical interlock and improve the wettability between the interlayer and the carbon / carbon composite. After the carbon / carbon composite was micro-oxidized at 630°C for 30 minutes and a Cu film was formed, the wettability of the liquid phase on the carbon / carbon composite increased. The shear strength of the joint prepared at 880°C for 10 minutes increased from 34.58MPa to 44.23MPa, and the fracture of the carbon / carbon composite after pretreatment occurred in the joint area. However, this method will cause a certain oxidation effect on the composite matrix when pre-oxidizing the composite, thereby damaging the fiber surface morphology.

[0007] In the literature “X. Song, H. Li, V. Casalegno, et al. In situ TiC ParticleReinforced TiCuZrNi Brazing Alloy for Joining C / C Composites to Ti6Al4V.International Journal of Applied Ceramic Technology. 2018, 15: 611~618.”, Song et al. used metal Cr to metallize the surface of carbon / carbon composites, and prepared a chromium carbide coating on the surface of carbon / carbon composites by solid phase reaction of C and Cr elements, thereby enhancing the wettability between Ti-Cu-Zr-Ni alloy brazing filler metal and carbon / carbon composites, thereby achieving a high-strength connection between carbon / carbon composites and TC4 (shear strength 52MP). However, the behavior of plating metal Cr coating on the surface of carbon / carbon composites by this method will form a large amount of brittle carbides on the side of carbon / carbon composites, which will increase the brittleness of the joint and make it unable to withstand high-strength loads.

[0008] In the literature "Yin Y, Wang J, Yang M, et al. Effect of Laser Cladding TiC on Microstructure and Mechanical Properties of TC4| C / C Bonded Joint[J]. Journal of Materials Engineering and Performance. 2024: 1-8.", Yin et al. used laser cladding to coat TiC on the surface of TC4 before brazing to improve the mechanical properties of the joints bonded to TC4 and carbon / carbon composites, and used AgCuTi as the brazing material. The results show that under the conditions of brazing temperature of 880℃, pressure of 5MPa, and holding time of 10min, the typical microstructure of the joint is carbon / carbon composite material|AgCuTi. ss + Ti x Cu |TiC |TC4. After the surface modification of TC4, the average shear strength increased to 17.3MPa, an increase of 152.2%. The fracture position was transferred from the interface area of ​​the carbon / carbon side of the joint to the carbon / carbon matrix. However, the joint prepared by this method generated a TiC coating under the action of high-temperature laser. Due to the high temperature of the laser, the surface of the carbon / carbon composite material near the solder side was damaged, and the TiC coating was brittle. It was easy to crack at the junction of the coating and the carbon / carbon composite material under the action of external force.

[0009] Therefore, there is an urgent need for a base material modification process that can not only improve the poor connection performance and easy failure of carbon / carbon composites and dissimilar metals, but also ensure the strength of the base material and joints, taking into account the high strength of carbon / carbon composites and the high plasticity of GH3230 to meet the needs of lightweight and high heat flux density thermal conductivity occasions. Summary of the invention

[0010] In view of the problems in the prior art that carbon / carbon composite materials have poor connection performance with dissimilar metals and are prone to failure, the present invention provides a carbon / carbon composite material, a modification method and a nickel-based high-temperature alloy brazing method thereof.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for modifying a carbon / carbon composite material, comprising: The carbon / carbon composite material is embedded by Si powder, C powder and Al2O3 to prepare a SiC coating modified base material; wherein the mass ratio of the Si powder, C powder and Al2O3 is (40-70): (20-50): (5-10); The SiC coating modified parent material is sprayed with Mo-Si slurry to obtain a SiC-Mo-Si modified carbon / carbon composite material; wherein, by mass percentage, the Mo-Si slurry comprises 44% to 54% of anhydrous ethanol, 0.5% of PVB, 0.5% of NaF powder and 45% to 55% of Mo-Si mixed powder, the Mo-Si mixed powder comprises Mo powder and Si powder, and the mass ratio of the Mo powder to the Si powder is (30 to 50): (50 to 70); The SiC-Mo-Si modified carbon / carbon composite material is heat treated and cured to obtain a modified carbon / carbon composite material, thereby completing the modification of the carbon / carbon composite material.

[0012] Optionally, the method of preparing a SiC coating modified parent material by embedding the carbon / carbon composite material with Si powder, C powder and Al2O3 is: Mix Si powder, C powder and Al2O3 evenly, and dry to obtain a mixed powder; Performing surface treatment on the carbon / carbon composite material connection surface to obtain a surface-treated carbon / carbon composite material; The surface treated carbon / carbon composite material is buried in the mixed powder, and is sealed, vacuum heated, cooled, the residual powder on the surface is removed, cleaned and dried in sequence to obtain a SiC coating modified base material.

[0013] Optionally, the vacuum heating is performed at a temperature of 1500° C. to 2100° C. for a time of 1 to 3 hours.

[0014] Optionally, the method of spraying the SiC coating modified parent material with Mo-Si slurry to obtain the SiC-Mo-Si modified carbon / carbon composite material is: The SiC coating modified base material is placed in anhydrous ethanol for cleaning and drying to obtain a cleaned SiC coating modified base material; Prepare Mo-Si slurry; The Mo-Si slurry is sprayed onto the cleaned surface of the SiC coating modified parent material, and dried to obtain a SiC-Mo-Si modified carbon / carbon composite material.

[0015] Optionally, the temperature of the heat treatment curing is 1500° C. to 2000° C., and the insulation time is 2 to 4 hours.

[0016] A carbon / carbon composite material is modified by the above modification method.

[0017] A method for brazing the carbon / carbon composite material and a nickel-based high-temperature alloy, comprising: Performing surface treatment on the nickel-based high-temperature alloy to be welded to obtain the nickel-based high-temperature alloy after surface treatment; Prepare brazing slurry; Applying brazing slurry to the connection surface of the modified carbon / carbon composite material and the connection surface of the surface-treated nickel-based high-temperature alloy, and compacting them to form a sandwich structure; The sandwich structure is subjected to temperature-raising brazing to obtain a connecting piece of the carbon / carbon composite material and the nickel-based high-temperature alloy, thereby completing the brazing of the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0018] Optionally, the thickness of the brazing slurry applied to the connection surface of the modified carbon / carbon composite material and the connection surface of the nickel-based high-temperature alloy after surface treatment is 100 to 300 μm.

[0019] Optionally, the brazing slurry is a paste slurry including a nickel-based brazing material and a binder; the binder includes vaseline and liquid paraffin in a mass ratio of 1:1.

[0020] Optionally, the sandwich structure is subjected to temperature-raising brazing to obtain a carbon / carbon composite material and a nickel-based high-temperature alloy connector, and the method for completing the brazing of the carbon / carbon composite material and the nickel-based high-temperature alloy is: The sandwich structure is heated to 900°C to 1200°C at a heating rate of 10°C / min to 11°C / min, kept warm for 10 to 30 min, and then cooled to 600°C at 3°C / min to 4°C / min to obtain a connecting piece of the carbon / carbon composite material and the nickel-based high-temperature alloy, thereby completing the brazing of the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a carbon / carbon composite material modification method. The method comprises the following steps: embedding the carbon / carbon composite material with Si powder, C powder and Al2O3 to prepare a SiC coating modified mother material; forming a SiC-based coating on the surface of the embedded carbon / carbon composite material; spraying the SiC coating modified mother material with Mo-Si slurry to obtain a SiC-Mo-Si modified carbon / carbon composite material; and heat-treating and curing the SiC-Mo-Si modified carbon / carbon composite material to obtain a modified carbon / carbon composite material. The modification of the carbon / carbon composite material is completed so that the finally obtained modified carbon / carbon composite material is sequentially attached with a SiC-based coating and a Mo-Si phase-based coating, hereinafter referred to as a SiC-MoSi2 composite coating. The CTE of the SiC-based coating is 4.5×10 −6 / ℃, the CTE of the coating mainly composed of Mo-Si phase is 8.3×10 −6 / ℃, the thermal expansion of the two coatings is between that of the base material and the nickel-based brazing filler metal, which effectively relieves the thermal stress caused by the mismatch of thermal expansion in the joint during thermal cycles, thereby reducing the formation and expansion of cracks and improving the thermal shock resistance and long-term service stability of the brazed joint. Secondly, the setting of the two coatings can improve the wettability and interface bonding strength between the brazing filler metal and the base material, optimize the interface reaction, and form a uniform and continuous brazing layer. Among them, the SiC-based coating has excellent chemical stability and wetting properties. The main component (Ni) in the BNi-2 brazing filler metal forms a good wetting contact with the SiC coating, which significantly improves the interface bonding quality. Compared with the surface of the carbon / carbon composite material without embedding modification, the SiC-based coating can effectively reduce the wetting angle of the brazing filler metal, increase the thickness of the chemical bonding layer, form a dense and tough bonding layer, and thus improve the joint bonding strength. At the same time, the SiC-based coating can effectively inhibit the generation of adverse reaction phases, optimize the interface microstructure and enhance the joint performance by forming a physical and chemical barrier to reduce the direct contact between the surface of the carbon / carbon composite material and the brazing filler metal. In addition, the introduction of Mo element in the middle layer of the brazed joint provides sufficient reaction conditions for constructing the Mo-Ni-Si system. First, the solid solution reaction between Mo and Ni has a significant effect on the joint performance. Since the Mo atom (radius of about 140 pm) is similar to the Ni atom (radius of about 124 pm), Mo can form a stable solid solution in the nickel matrix. After Mo atoms enter the Ni lattice, they cause lattice distortion and hinder dislocation movement, thereby significantly improving the strength and hardness of the alloy. The addition of Mo also plays an important role in high-temperature performance. It can stabilize the grain structure, inhibit grain growth at high temperature, and enhance high-temperature strength and creep resistance. At the same time, Mo can promote the formation of complex solid solutions or precipitation phases of elements such as Cr, further improving the alloy performance. In terms of welding performance, the introduction of Mo can reduce the brittleness of the joint and enhance heat resistance and corrosion resistance. The thinner Mo-based coating can regulate the Mo content, thereby controlling the grain size of the Mo-based compound, which can not only improve the material strength through solid solution strengthening and precipitation strengthening, but also inhibit grain growth through grain boundary pinning effect, and increase the nucleation driving force to promote grain refinement. However, the regulation of Mo content on grain size needs to be maintained within an appropriate range. Smaller grains can significantly improve the creep resistance and high-temperature strength of the material, while excessively large grains can easily cause performance degradation. Therefore, the amount of Mo powder needs to be strictly controlled during modification.At the same time, when preparing the composite coating, the coating mainly composed of Mo-Si phase is physically bonded to the surface of the SiC coating through mechanical biting. During the high-temperature sintering process, local diffusion bonding and chemical reactions are accompanied to further enhance the interface bonding strength. Among them, the realization of mechanical biting is mainly reflected in: during high-temperature sintering, the sprayed particles will fill and fit each other, be squeezed together at high temperature, and the concave and convex parts between the particles will be stuck to each other, like the biting between mechanical gears, thereby achieving physical bonding, so that the coating forms a preliminary connection with the underlying SiC coating and the carbon / carbon composite material. The occurrence of local diffusion reaction means that under the high-temperature sintering environment of 1600°C, the thermal motion of atoms becomes very intense. The Si atoms in the Mo-Si-based coating, the Si atoms and C atoms in the SiC-based coating, and the C atoms in the carbon / carbon composite material will obtain enough energy due to this thermal motion, diffuse across the interface, and migrate from the high-concentration area to the low-concentration area. This mutual diffusion of atoms will form a region with a gradient composition at the interface, making the composition at the interface more uniform, reducing the interfacial stress concentration caused by the difference in composition, and enhancing the bonding between the coatings and between the coating and the substrate. Finally, a stable interface reaction is achieved through chemical bonding. At high temperatures, a series of chemical reactions may occur between the Mo-Si phase-based coating, the SiC-based coating, and the carbon / carbon composite material. These compounds act as a "bridge" to connect different coatings and substrates together, greatly enhancing the bonding strength of the interface, so that the entire coating system can maintain good performance under complex environments such as high temperature. In short, the introduction of SiC-MoSi2 composite coating not only solves the problem of poor connection performance and easy failure between carbon / carbon composite materials and dissimilar metals, but also optimizes the microscopic interface of the parent material and the connector as a physical and chemical barrier, and ensures the strength of the parent material and the connector.

[0022] A carbon / carbon composite material is modified by the above modification method. A uniform and stable SiC-MoSi2 composite coating is formed on the surface of the carbon / carbon composite material, so that when the carbon / carbon composite material is brazed and connected with a nickel-based high-temperature alloy, good wettability and interface bonding strength are formed, and a uniform and continuous brazing layer is formed, which is more tightly connected with the nickel-based high-temperature alloy, and can better meet the needs of light-weight and high-heat flux density thermal conductivity occasions.

[0023] The present invention also provides a method for brazing the carbon / carbon composite material and the nickel-based high-temperature alloy. The method comprises the following steps: surface treating the nickel-based high-temperature alloy to be welded to obtain the surface-treated nickel-based high-temperature alloy; preparing a brazing slurry; applying the brazing slurry to the connection surface of the modified carbon / carbon composite material and the surface-treated nickel-based high-temperature alloy, and compacting the surface to form a sandwich structure; and brazing the sandwich structure at a high temperature to obtain a carbon / carbon composite material and a nickel-based high-temperature alloy connector, thereby completing the brazing of the carbon / carbon composite material and the nickel-based high-temperature alloy. The joint brazed by the method has a higher welding strength, and the chemical bonding between the base material and the brazing material is stable. The method is suitable for the connection of large-sized components, and will not cause high-temperature decomposition failure. The method can better meet the service requirements under high temperatures, and provides a research direction for the brazing of other composite materials and metal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a schematic flow chart of a carbon / carbon composite material modification method of the present invention.

[0025] Figure 2 The present invention is a simplified process flow chart of a carbon / carbon composite material modification method and a brazing connection process with a nickel-based high-temperature alloy according to an embodiment of the present invention, wherein a is a schematic diagram of preparing a SiC coating modified base material, b is a schematic diagram of preparing a SiC-Mo-Si modified carbon / carbon composite material, and c is a schematic diagram of the joint assembly of the new method for brazing connection of the modified carbon / carbon composite material with a nickel-based high-temperature alloy according to the present invention.

[0026] Figure 3 The surface morphology of the coating prepared in Example 1 of the present invention and the morphology of the intermediate layer of the joint after the coating is introduced into the joint, wherein a is the surface morphology of the coating, and b is the morphology of the intermediate layer of the joint between the coating-modified carbon / carbon composite material and the GH3230.

[0027] Figure 4 The surface morphology of the coating prepared in comparative example 1 of the present invention and the morphology of the intermediate layer of the joint after the coating is introduced into the joint, wherein a is the surface morphology of the coating, and b is the morphology of the intermediate layer of the joint between the coating-modified carbon / carbon composite material and the GH3230.

[0028] Figure 5 The surface morphology of the coating prepared in Example 2 of the present invention and the morphology of the intermediate layer of the joint after the coating is introduced into the joint, wherein a is the surface morphology of the coating, and b is the morphology of the intermediate layer of the joint between the coating-modified carbon / carbon composite material and the GH3230.

[0029] Figure 6 The surface morphology of the coating prepared in comparative example 2 of the present invention and the morphology of the intermediate layer of the joint after the coating is introduced into the joint, wherein a is the surface morphology of the coating, and b is the morphology of the intermediate layer of the joint between the coating-modified carbon / carbon composite material and the GH3230.

[0030] Figure 7 The surface morphology of the coating prepared in Example 3 of the present invention and the morphology of the intermediate layer of the joint after the coating is introduced into the joint, wherein a is the surface morphology of the coating, and b is the morphology of the intermediate layer of the joint between the coating-modified carbon / carbon composite material and the GH3230.

[0031] Figure 8 The surface morphology of the coating prepared in comparative example 3 of the present invention and the morphology of the intermediate layer of the joint after the coating is introduced into the joint, wherein a is the surface morphology of the coating, and b is the morphology of the intermediate layer of the joint between the coating-modified carbon / carbon composite material and the GH3230. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0033] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0034] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0035] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0036] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0038] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0039] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0040] See also Figure 1 The present invention provides a method for modifying a carbon / carbon composite material, comprising: S11: Using Si powder, C powder and Al2O3 to embed the carbon / carbon composite material to prepare a SiC coating modified base material; wherein the mass ratio of the Si powder, C powder and Al2O3 is (40-70): (20-50): (5-10), preferably: (40-60): (30-50): (8-10), and more preferably: (50-60): (40-50): 10. The specific method is: S11.1: Mix Si powder, C powder and Al2O3 uniformly, dry them and obtain a mixed powder, specifically: weigh the corresponding Si powder, C powder and Al2O3 according to the mass ratio using an electronic balance, stir them manually in a mortar for 2 to 3 hours, then use a planetary ball mill to mix them for more than 24 hours, finally sieve them, stir them manually in a mortar for 2 to 3 hours, and dry them in a 373K oven for at least 5 hours to obtain a mixed powder for use; S11.2: Surface treatment is performed on the carbon / carbon composite material connection surface to obtain a surface-treated carbon / carbon composite material, specifically: The carbon / carbon composite material and the nickel-based high-temperature alloy are processed into 15mm×10mm×4mm parent materials (the shape and specifications of the parent materials are determined according to the actual use conditions and requirements) by using a wire cutting machine for standby use; the carbon / carbon composite material connection surface is polished using 600-mesh silicon carbide sandpaper to ensure that the surface roughness and roughness of the carbon / carbon composite material connection surface are consistent; the polished carbon / carbon composite material is ultrasonically cleaned in anhydrous ethanol to remove the surface carbon powder, and dried to complete the surface treatment; S11.3: The surface treated carbon / carbon composite material is buried in the mixed powder, and the steps of sealing, vacuum heating, cooling, removing the residual powder on the surface, cleaning and drying are performed in sequence to obtain a SiC coating modified base material, specifically: Graphite paper is lined on the inner wall of the graphite crucible, and then the mixed powder is spread on the bottom of the crucible, and then the surface-treated carbon / carbon composite material is placed on the top, and then the mixed powder is spread until the surface-treated carbon / carbon composite material is fully buried, and finally a layer of graphite paper and carbon felt are placed on the top of the buried powder, and a layer of C powder is spread on the carbon felt and covered with graphite paper to seal it; Put the graphite crucible into the ultra-high temperature graphite heating furnace, then evacuate and maintain the pressure for 10 minutes to check if the air tightness is normal, then introduce Ar gas to normal pressure (the whole embedding process is carried out under Ar gas protection), check that the cooling water is normal and set the temperature control program to start heating, the heating furnace is heated to 1500℃~2100℃, and kept warm for 1~3h; After the insulation is finished, the graphite heating furnace is slowly cooled to room temperature according to the cooling program, and then the graphite crucible is taken out of the heating furnace and the treated sample is taken out of the crucible, the residual powder on the surface is removed, and then the sample is cleaned and dried to obtain the SiC coating modified base material; S12: Spraying the SiC coating modified base material with Mo-Si slurry to obtain a SiC-Mo-Si modified carbon / carbon composite material; wherein, by mass percentage, the Mo-Si slurry comprises 44% to 54% anhydrous ethanol, 0.5% polyvinyl butyral (PVB), 0.5% NaF powder and 45% to 55% Mo-Si mixed powder, the Mo-Si mixed powder comprises Mo powder and Si powder, and the mass ratio of the Mo powder to the Si powder is (30 to 50): (50 to 70), preferably: (40 to 50): (60 to 70), and more preferably: 40:60. Specifically: S12.1: The SiC coating modified base material is placed in anhydrous ethanol for cleaning and drying to obtain the cleaned SiC coating modified base material, specifically: The SiC coating modified base material is ultrasonically cleaned in anhydrous ethanol for 20 to 25 minutes, and then placed in an oven for drying to obtain the cleaned SiC coating modified base material for later use.

[0041] S12.2: Prepare Mo-Si slurry, specifically: Mo powder and Si powder were evenly mixed by ball milling for 24 hours in a mass ratio of (30-50): (50-70) to obtain Mo-Si mixed powder; 44% to 54% of anhydrous ethanol, 0.5% of PVB, 0.5% of NaF powder and 45% to 55% of Mo-Si mixed powder are respectively prepared into slurry according to mass percentage, and then the slurry is stirred evenly with a magnetic stirrer to obtain Mo-Si slurry for standby use; S12.3: Spraying the Mo-Si slurry onto the cleaned surface of the SiC coating modified base material, and drying to obtain a SiC-Mo-Si modified carbon / carbon composite material, specifically: The prepared Mo-Si slurry is evenly applied on the cleaned surface of the SiC coating, and then placed in an oven for drying to obtain a SiC-Mo-Si modified carbon / carbon composite material; S13: heat-treating and curing the SiC-Mo-Si modified carbon / carbon composite material to obtain a modified carbon / carbon composite material, and completing the modification of the carbon / carbon composite material, specifically: The SiC-Mo-Si modified carbon / carbon composite material is placed in a high-temperature tubular furnace and heat treated in a protective atmosphere. The specific process is as follows: the dried SiC-Mo-Si modified carbon / carbon composite material is placed in a corundum crucible, and then the crucible is placed in the tubular furnace; the tubular furnace is locked and sealed, evacuated and maintained in vacuum for 1 to 2 hours, and after checking to make sure that the equipment is airtight, Ar gas is slowly passed to normal pressure; the furnace temperature is raised to 1500°C to 2100°C, preferably 1600°C to 2000°C, at a heating rate of 5K / min, and kept warm for 2 to 4 hours; after the insulation is completed, the tubular furnace is cooled to room temperature at a cooling rate of 10K / min, and finally the Ar gas is turned off, the locking valve is opened and the crucible is taken out to obtain the modified carbon / carbon composite material, thereby completing the modification of the carbon / carbon composite material.

[0042] The present invention also provides a carbon / carbon composite material, which is modified by the above-mentioned modification method. The surface of the carbon / carbon composite material forms a uniform and stable SiC-MoSi2 composite coating, so that when the carbon / carbon composite material is brazed and connected with the nickel-based high-temperature alloy, good wettability and interface bonding strength are formed, and a uniform and continuous brazing layer is formed, which is more tightly connected with the nickel-based high-temperature alloy, and can better meet the requirements of light-weight and high heat flux density heat conduction occasions.

[0043] The present invention also provides a method for brazing the carbon / carbon composite material and the nickel-based high-temperature alloy, comprising: S21: performing surface treatment on the nickel-based high-temperature alloy to be welded to obtain the nickel-based high-temperature alloy after surface treatment, specifically: Use 180-mesh and 600-mesh sandpaper to grind the connection surfaces of the nickel-based high-temperature alloy in turn to remove the surface oxide scale and corrosion layer; The polished nickel-based high-temperature alloy is ultrasonically cleaned in anhydrous ethanol to remove surface metal powder, and dried to complete surface treatment to obtain a surface-treated nickel-based high-temperature alloy; S22: Prepare brazing slurry, specifically: Adding a binder to the nickel-based solder until it becomes a paste slurry to obtain a solder slurry, wherein the binder includes vaseline and liquid paraffin, wherein the mass ratio of the vaseline and the liquid paraffin is 1:1, and the vaseline and the liquid paraffin are fully melted and stirred in an oil bath at 70° C. to 80° C. to form a viscous white colloidal mixture, which is the binder; S23: Apply the brazing slurry to the connection surface of the modified carbon / carbon composite material and the surface-treated nickel-based high-temperature alloy, and compact it to form a sandwich structure. Specifically, apply the brazing slurry to the connection surface of the modified carbon / carbon composite material and the surface-treated nickel-based high-temperature alloy, and squeeze the modified carbon / carbon composite material connection surface coated with the brazing slurry and the surface-treated nickel-based high-temperature alloy connection surface relative to form a sandwich structure, scrape off the excess brazing material with a scraper, and let it stand for 24 hours. The nickel-based high-temperature alloy is on top of the carbon / carbon composite material, and the carbon / carbon composite material and the nickel-based high-temperature alloy are formed into a tight physical connection through the brazing material layer by using the metal's own gravity. Among them, the thickness of the brazing slurry is 100 to 300 μm.

[0044] S24: The sandwich structure is subjected to temperature-raising brazing to obtain a connecting piece of the carbon / carbon composite material and the nickel-based high-temperature alloy, and the brazing of the carbon / carbon composite material and the nickel-based high-temperature alloy is completed, specifically: The sandwich structure is placed under vacuum conditions, heated to 900°C to 1200°C at a heating rate of 10°C / min to 11°C / min, kept warm for 10 to 30 minutes, and then cooled to 600°C at a rate of 3°C / min to 4°C / min to complete the brazing connection between the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0045] The joints brazed using this method have higher welding strength, the chemical bond between the base material and the brazing material is stable, it is suitable for the connection of large-size components, and will not fail due to high-temperature decomposition. It can better meet the needs of service under high temperatures and provides a research direction for the brazing of other composite materials and metal materials.

[0046] Example 1 See also Figure 2 First, Si powder, C powder and Al2O3 were weighed separately in a mass ratio of 60:30:10 using an electronic balance, and manually stirred in a mortar for 2 hours. Then, a planetary ball mill was used to mix the mixture for more than 24 hours. Finally, the mixture was sieved and manually stirred in a mortar for 3 hours, and dried in a 373K oven for at least 5 hours to obtain a mixed powder for use.

[0047] The carbon / carbon composite material and the nickel-based high-temperature alloy are processed into 15mm×10mm×4mm base materials by wire cutting machine for later use.

[0048] The carbon / carbon composite material connection surface was polished using 600-grit silicon carbide sandpaper to ensure that the surface roughness and roughness of the carbon / carbon composite material connection surface were consistent, and the polished carbon / carbon composite material was ultrasonically cleaned in anhydrous ethanol to remove surface carbon powder and dried to complete surface pretreatment.

[0049] Line the inner wall of the graphite crucible with graphite paper, then spread the mixed powder on the bottom of the crucible, and then place the surface treated carbon / carbon composite material on top, and then spread the mixed powder until the surface treated carbon / carbon composite material is fully buried, and finally place a layer of graphite paper and carbon felt on the top of the buried powder, spread a layer of C powder on the carbon felt, cover it with graphite paper and seal it.

[0050] Place the graphite crucible in an ultra-high temperature graphite heating furnace, then evacuate and maintain the pressure for 10 minutes. After checking that the airtightness is normal, introduce Ar gas to normal pressure. After checking that the cooling water is normal, set the temperature control program to start heating. The heating furnace is heated to 1900℃ and maintained for 2 hours.

[0051] After the insulation is completed, the graphite heating furnace is slowly cooled to room temperature according to the cooling program, and then the graphite crucible is taken out of the heating furnace and the treated sample is taken out of the crucible, the residual powder on the surface is removed, and then it is cleaned and dried to obtain the SiC coating modified base material.

[0052] The prepared SiC coating modified base material was ultrasonically cleaned in anhydrous ethanol for 25 minutes, and placed in an oven for drying to obtain the cleaned SiC coating modified base material for later use.

[0053] The Mo powder and Si powder were evenly mixed by ball milling for 24 hours at a mass ratio of 40:60 to obtain a Mo-Si mixed powder; 44% of anhydrous ethanol, 0.5% of PVB, 0.5% of NaF powder and 55% of Mo-Si mixed powder were respectively prepared into slurry according to mass percentage, and then the slurry was stirred evenly with a magnetic stirrer for use.

[0054] The prepared slurry is evenly applied on the surface of the SiC coating modified base material, and then placed in an oven for drying to obtain a SiC-Mo-Si modified carbon / carbon composite material for standby use.

[0055] The SiC-Mo-Si modified carbon / carbon composite material that has been coated and dried is placed in a high-temperature tubular furnace and heat treated in a protective atmosphere. The specific process is as follows: the dried SiC-Mo-Si modified carbon / carbon composite material is placed in a corundum crucible, and then the crucible is placed in the tubular furnace; the tubular furnace is locked and sealed, evacuated and maintained in vacuum for 2 hours, and after checking to make sure that the equipment is airtight, Ar gas is slowly passed to normal pressure; the furnace temperature is raised to 1700°C at a heating rate of 5K / min, and kept warm for 3 hours; after the insulation is completed, the tubular furnace is cooled to room temperature at a cooling rate of 10K / min, and finally the Ar gas is turned off, the locking valve is disassembled and the crucible is taken out to obtain the modified carbon / carbon composite material, thereby completing the modification of the carbon / carbon composite material.

[0056] Use 180-mesh and 600-mesh sandpaper to grind the connection surfaces of the nickel-based high-temperature alloy in turn to remove the surface oxide scale and corrosion layer.

[0057] The polished nickel-based high-temperature alloy is ultrasonically cleaned in anhydrous ethanol to remove surface metal powder, dried, and surface treated to obtain a nickel-based high-temperature alloy after surface treatment.

[0058] The nickel-based solder is added to a binder to make it into a paste slurry. The binder is a mixture of vaseline and liquid paraffin in a mass ratio of 1:1. The mixture is fully melted and stirred in an oil bath at 70° C. to form a viscous white colloidal mixture.

[0059] The brazing slurry is applied to the treated nickel-based superalloy connection surface to be welded and the surface-modified carbon / carbon composite material connection surface, and the two parent materials to be welded with the brazing slurry are placed opposite to each other and squeezed against each other to make the excess brazing material flow out between the carbon / carbon composite material and the nickel-based superalloy. The two are tightly connected, and the excess brazing material is scraped off with a scraper. After standing for 24 hours, the nickel-based superalloy is placed on the carbon / carbon composite material, and the carbon / carbon composite material and the nickel-based superalloy are tightly physically connected through the brazing material layer by using the metal's own gravity. The thickness of the brazing slurry is 200μm.

[0060] The sandwich structure was placed under vacuum conditions, heated to 1050°C at a heating rate of 10°C / min, kept warm for 15 minutes, and then cooled to 600°C at a rate of 4°C / min to complete the brazing connection between the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0061] Comparative Example 1 First, Si powder, C powder and Al2O3 were weighed separately in a mass ratio of 60:30:10 using an electronic balance, and manually stirred in a mortar for 2 hours. Then, a planetary ball mill was used to mix the mixture for more than 24 hours. Finally, the mixture was sieved and manually stirred in a mortar for 3 hours, and dried in a 373K oven for at least 5 hours to obtain a mixed powder for use.

[0062] The carbon / carbon composite material and the nickel-based high-temperature alloy are processed into 15mm×10mm×4mm base materials by wire cutting machine for later use.

[0063] The carbon / carbon composite material connection surface is polished using 600-grit silicon carbide sandpaper to ensure that the surface roughness and roughness of the carbon / carbon composite material connection surface are consistent.

[0064] The polished carbon / carbon composite material is ultrasonically cleaned in anhydrous ethanol to remove surface carbon powder, and then dried to complete the surface pretreatment.

[0065] Line the inner wall of the graphite crucible with graphite paper, then spread the mixed powder on the bottom of the crucible, and then place the carbon / carbon sample on top of it, followed by spreading the mixed powder until the sample is fully buried, and finally place a layer of graphite paper and carbon felt on the top of the buried powder in sequence, spread a layer of C powder on the carbon felt, cover it with graphite paper and seal it.

[0066] Place the graphite crucible in an ultra-high temperature graphite heating furnace, then evacuate and maintain the pressure for 10 minutes. After checking that the airtightness is normal, introduce Ar gas to normal pressure. After checking that the cooling water is normal, set the temperature control program to start heating. The heating furnace is heated to 1900℃ and maintained for 2 hours.

[0067] After the insulation is completed, the graphite heating furnace is slowly cooled to room temperature according to the cooling program, and then the graphite crucible is taken out of the heating furnace and the treated sample is taken out of the crucible, the residual powder on the surface is removed, and then it is cleaned and dried to obtain the SiC coating modified base material.

[0068] The prepared SiC coating modified base material was ultrasonically cleaned in anhydrous ethanol for 25 minutes, and placed in an oven for drying to obtain the cleaned SiC coating modified base material for later use.

[0069] 44% of anhydrous ethanol, 0.5% of PVB, 0.5% of NaF powder and 55% of Mo powder were respectively prepared into slurry according to mass percentage, and then the slurry was stirred evenly with a magnetic stirrer for use.

[0070] The prepared slurry is evenly applied on the surface of the SiC coating modified base material, and then placed in an oven for drying to obtain a SiC-Mo modified carbon / carbon composite material for later use.

[0071] The SiC-Mo-Si modified carbon / carbon composite material that has been coated and dried is placed in a high-temperature tubular furnace and heat treated in a protective atmosphere. The specific process is as follows: the dried SiC-Mo-Si modified carbon / carbon composite material is placed in a corundum crucible, and then the crucible is placed in the tubular furnace; the tubular furnace is locked and sealed, evacuated and maintained in vacuum for 2 hours, and after checking to make sure that the equipment is airtight, Ar gas is slowly passed to normal pressure; the furnace temperature is raised to 1700°C at a heating rate of 5K / min, and kept warm for 3 hours; after the insulation is completed, the tubular furnace is cooled to room temperature at a cooling rate of 10K / min, and finally the Ar gas is turned off, the locking valve is disassembled and the crucible is taken out to obtain the modified carbon / carbon composite material, thereby completing the modification of the carbon / carbon composite material.

[0072] Use 180-mesh and 600-mesh sandpaper to grind the connection surfaces of the nickel-based high-temperature alloy in turn to remove the surface oxide scale and corrosion layer.

[0073] The polished nickel-based high-temperature alloy is ultrasonically cleaned in anhydrous ethanol to remove surface metal powder, dried, and surface treated to obtain a nickel-based high-temperature alloy after surface treatment.

[0074] The nickel-based solder is added to a binder to make it into a paste slurry. The binder is a mixture of vaseline and liquid paraffin in a mass ratio of 1:1. The mixture is fully melted and stirred in an oil bath at 70° C. to form a viscous white colloidal mixture.

[0075] The brazing slurry is applied to the treated nickel-based superalloy connection surface to be welded and the surface-modified carbon / carbon composite material connection surface, and the two parent materials to be welded with the brazing slurry are placed opposite to each other and squeezed against each other to make the excess brazing material flow out between the carbon / carbon composite material and the nickel-based superalloy. The two are tightly connected, and the excess brazing material is scraped off with a scraper. After standing for 24 hours, the nickel-based superalloy is placed on the carbon / carbon composite material, and the carbon / carbon composite material and the nickel-based superalloy are tightly physically connected through the brazing material layer by using the metal's own gravity. The thickness of the brazing slurry is 200μm.

[0076] The sandwich structure was placed under vacuum conditions, heated to 1050°C at a heating rate of 10°C / min, kept warm for 15 minutes, and then cooled to 600°C at a rate of 4°C / min to complete the brazing connection between the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0077] See also Figure 3 and Figure 4, the surface morphology of the coating obtained in Example 1 was compared with that in Comparative Example 1 and introduced into the joint. The results showed that after the mixed powder of Mo and Si in the ratio of 2:3 was cured at 1700°C for 3h, the fusion of Mo particles and Si particles on the surface of the joint obtained by brazing in Example 1 was relatively uniform, and the two were completely fused to form a dense coating. At high temperature, the spray coating first came into physical contact with the substrate, and then with the increase of temperature, the Si element in the Mo-Si coating and the SiC surface would diffuse Si elements, and at the same time, part of Si and Mo penetrated into the porous SiC coating, and pinning occurred. The dual reaction of physical penetration and chemical diffusion made the Mo-Si coating physically adsorbed by spraying firmly bonded. The surface structure of the coating showed a porous and rough morphology, and the overall distribution uniformity of the coating was good, indicating that the densification process during particle accumulation and sintering was relatively perfect. ; When it was introduced into the brazed joint, the chemical bonding layer of the intermediate layer of the joint near the modified carbon / carbon base material was mainly composed of Ni-Si compounds generated by the diffusion of Si elements and Si-rich Ni ss Solid solution, Ni-Si compound appears as small black particles distributed in Si-rich Ni ss On the substrate, the carbon elements of the carbon / carbon matrix diffuse into the brazing material to form a dense and continuous chemical reaction layer. This area is the key to achieve chemical bonding between the brazing joint and the modified carbon / carbon base material, which improves the joint strength and reduces interface defects. The plastic layer of the intermediate phase distribution is composed of dark gray Cr-rich Ni ss , light gray Si-rich Ni ss Alternating distribution, accompanied by white Mo-rich Ni ss The three plastic phases effectively improve the strength of the intermediate layer through solid solution strengthening and uniform distribution, while relieving residual stress and giving the joint good mechanical properties. In addition, the element diffusion layer on the metal side is mainly composed of needle-shaped Cr ssUniformly distributed on the Si-rich Niss substrate, the Cr element forms a fine solid solution phase with the brazing material through diffusion, achieving a close combination of the nickel-based brazing material and the nickel-based high-temperature alloy, and ensuring the high-temperature performance of the joint. In comparative example 1, because no Si powder is added during spraying, only Mo powder is added, and there is no diffusion between Si powder and the matrix parent material SiC-carbon / carbon composite material to form a combination. At this time, the coating surface is only connected to each other through the physical contact between Mo powder and SiC coating. Mo particles agglomerate on the coating surface, and after high-temperature heat treatment, the coating surface cracks due to thermal stress, exposing the SiC coating at the bottom. The coating prepared by this process is introduced into the joint. It is found that due to the poor bonding between the coating and the joint, at high temperature, although the Mo element diffuses into the middle layer, a large number of holes and cracks appear between the carbon / carbon composite material and the metal brazing material, and because there is no Si element in the Mo coating, compared with Example 1, the chemical reaction layer of the joint at this time does not participate in the diffusion reaction of the Si element, and the joint interface bonding is poor.

[0078] Example 2 See also Figure 2 First, Si powder, C powder and Al2O3 were weighed separately in a mass ratio of 40:50:10 using an electronic balance, and manually stirred in a mortar for 3 hours. Then, a planetary ball mill was used to mix the mixture for more than 24 hours. Finally, the mixture was sieved and manually stirred in a mortar for 3 hours, and dried in a 373K oven for at least 5 hours to obtain a mixed powder for use.

[0079] The carbon / carbon composite material and the nickel-based high-temperature alloy are processed into 15mm×10mm×4mm base materials by wire cutting machine for later use.

[0080] The carbon / carbon composite material connection surface was polished using 600-grit silicon carbide sandpaper to ensure that the surface roughness and roughness of the carbon / carbon composite material connection surface were consistent. The polished carbon / carbon composite material was ultrasonically cleaned in anhydrous ethanol to remove the surface carbon powder, and dried to complete the surface pretreatment.

[0081] Line the inner wall of the graphite crucible with graphite paper, then spread the mixed powder on the bottom of the crucible, and then place the carbon / carbon sample on top of it, followed by spreading the mixed powder until the sample is fully buried, and finally place a layer of graphite paper and carbon felt on the top of the buried powder in sequence, spread a layer of C powder on the carbon felt, cover it with graphite paper and seal it.

[0082] Place the graphite crucible in an ultra-high temperature graphite heating furnace, then evacuate and maintain the pressure for 10 minutes. After checking that the airtightness is normal, introduce Ar gas to normal pressure. After checking that the cooling water is normal, set the temperature control program to start heating. The heating furnace is heated to 1500℃ and kept warm for 3 hours.

[0083] After the insulation is completed, the graphite heating furnace is slowly cooled to room temperature according to the cooling program, and then the graphite crucible is taken out of the heating furnace and the treated sample is taken out of the crucible, the residual powder on the surface is removed, and then it is cleaned and dried to obtain the SiC coating modified base material.

[0084] The prepared SiC coating modified base material was ultrasonically cleaned in anhydrous ethanol for 20 minutes and placed in an oven for drying.

[0085] The Mo powder and Si powder were evenly mixed by ball milling for 24 hours in a ratio of 50:50 by mass to obtain a Mo-Si mixed powder; Anhydrous ethanol, PVB, NaF powder, and Mo-Si mixed powder were weighed in order according to the mass percentages of 45%, 0.5%, 0.5%, and 54% to prepare a slurry, and the slurry was stirred evenly with a magnetic stirrer to obtain Mo-Si slurry for later use.

[0086] The prepared Mo-Si slurry is evenly applied on the surface of the SiC coating modified base material, and then placed in an oven for drying to obtain a SiC-Mo-Si modified carbon / carbon composite material for standby use.

[0087] The SiC-Mo-Si modified carbon / carbon composite material is placed in a high-temperature tubular furnace and heat treated in a protective atmosphere. The specific process is as follows: the dried SiC-Mo-Si modified carbon / carbon composite material is placed in a corundum crucible, and then the crucible is placed in the tubular furnace; the tubular furnace is locked and sealed, evacuated and maintained in vacuum for 2 hours, and after checking to make sure that the equipment is airtight, Ar gas is slowly passed to normal pressure; the furnace temperature is raised to 1500°C at a heating rate of 5K / min, and kept warm for 4 hours; after the insulation is completed, the tubular furnace is cooled to room temperature at a cooling rate of 10K / min, and finally the Ar gas is turned off, the locking valve is disassembled and the crucible is taken out to obtain the modified carbon / carbon composite material, thereby completing the modification of the carbon / carbon composite material.

[0088] Use 180-mesh and 600-mesh sandpaper to grind the connection surfaces of the nickel-based high-temperature alloy in turn to remove the surface oxide scale and corrosion layer.

[0089] The polished nickel-based high-temperature alloy is ultrasonically cleaned in anhydrous ethanol to remove surface metal powder, and then dried to complete the surface treatment to obtain the nickel-based high-temperature alloy after the surface treatment.

[0090] The nickel-based solder is added to a binder to turn it into a paste slurry. The binder is a mixture of vaseline and liquid paraffin in a mass ratio of 1:1. The mixture is fully melted and stirred in an oil bath at 70°C to 80°C to form a viscous white colloidal mixture.

[0091] The brazing slurry is applied to the treated nickel-based superalloy connection surface to be welded and the surface-modified carbon / carbon composite material connection surface, and the pyrolytic carbon-modified molybdenum-nickel foam is placed between the carbon / carbon composite material connection surface and the nickel-based superalloy connection surface to be welded coated with the brazing slurry, and compacted to form a sandwich structure. During the compaction process, the two parent materials to be welded with the brazing slurry are placed opposite to each other and squeezed against each other, so that the excess brazing material between the carbon / carbon composite material and the nickel-based superalloy flows out, and the two are tightly connected. The excess brazing material is scraped off with a scraper, and the nickel-based superalloy is placed on the carbon / carbon composite material. The metal's own gravity is used to form a tight physical connection between the carbon / carbon composite material and the nickel-based superalloy through the brazing layer. Among them, the thickness of the brazing slurry is 300μm.

[0092] The sandwich structure was placed under vacuum conditions, heated to 900°C at a heating rate of 11°C / min, kept warm for 30 minutes, and then cooled to 600°C at a rate of 4°C / min to complete the brazing connection between the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0093] Comparative Example 2 First, Si powder, C powder and Al2O3 were weighed separately in a mass ratio of 40:50:10 using an electronic balance, and manually stirred in a mortar for 3 hours. Then, a planetary ball mill was used to mix the mixture for more than 24 hours. Finally, the mixture was sieved and manually stirred in a mortar for 3 hours, and dried in a 373K oven for at least 5 hours to obtain a mixed powder for use.

[0094] The carbon / carbon composite material and the nickel-based high-temperature alloy are processed into 15mm×10mm×4mm base materials by wire cutting machine for later use.

[0095] The carbon / carbon composite material connection surface was polished using 600-grit silicon carbide sandpaper to ensure that the surface roughness and roughness of the carbon / carbon composite material connection surface were consistent. The polished carbon / carbon composite material was ultrasonically cleaned in anhydrous ethanol to remove the surface carbon powder, and dried to complete the surface pretreatment.

[0096] Line the inner wall of the graphite crucible with graphite paper, then spread the mixed powder on the bottom of the crucible, and then place the carbon / carbon sample on top of it, followed by spreading the mixed powder until the sample is fully buried, and finally place a layer of graphite paper and carbon felt on the top of the buried powder in sequence, spread a layer of C powder on the carbon felt, cover it with graphite paper and seal it.

[0097] Place the graphite crucible in an ultra-high temperature graphite heating furnace, then evacuate and maintain the pressure for 10 minutes. After checking that the airtightness is normal, introduce Ar gas to normal pressure. After checking that the cooling water is normal, set the temperature control program to start heating. The heating furnace is heated to 1500℃ and kept warm for 3 hours.

[0098] After the insulation is completed, the graphite heating furnace is slowly cooled to room temperature according to the cooling program, and then the graphite crucible is taken out of the heating furnace and the treated sample is taken out of the crucible, the residual powder on the surface is removed, and then it is cleaned and dried to obtain the SiC coating modified base material.

[0099] The prepared SiC coating modified base material was ultrasonically cleaned in anhydrous ethanol for 20 minutes and placed in an oven for drying.

[0100] Mo powder and Si were evenly mixed by ball milling for 24 hours in a ratio of 50:50 by mass to obtain Mo-Si mixed powder.

[0101] Anhydrous ethanol, PVB, NaF powder and Mo-Si mixed powder were weighed in order according to the mass percentages of 45%, 0.5%, 0.5% and 54% to prepare a slurry, and then the slurry was stirred evenly with a magnetic stirrer for later use.

[0102] Use the prepared slurry to evenly apply the slurry on the surface of the SiC coating modified base material, and then put it in an oven to dry for use.

[0103] The coated and dried samples were placed in a high-temperature tubular furnace and heat treated in a protective atmosphere. The specific process was as follows: the dried SiC-Mo-Si modified carbon / carbon composite material was placed in a corundum crucible, and the crucible was placed in the tubular furnace; the tubular furnace was locked and sealed, evacuated and maintained in vacuum for 2 hours, and after checking to make sure that the equipment was airtight, Ar gas was slowly passed to normal pressure; the furnace temperature was raised to 1200°C at a heating rate of 5K / min and kept warm for 1 hour; after the insulation was completed, the tubular furnace was cooled to room temperature at a cooling rate of 10 K / min, and finally the Ar gas was turned off, the locking valve was opened and the crucible was taken out to obtain the SiC-Mo-Si composite coating modified carbon / carbon composite material.

[0104] Use 180-mesh and 600-mesh sandpaper to grind the connection surfaces of the nickel-based high-temperature alloy in turn to remove the surface oxide scale and corrosion layer.

[0105] The polished nickel-based high-temperature alloy is ultrasonically cleaned in anhydrous ethanol to remove surface metal powder, and then dried to complete the surface treatment to obtain the nickel-based high-temperature alloy after the surface treatment.

[0106] The nickel-based solder is added to a binder to make it into a paste slurry. The binder is a mixture of vaseline and liquid paraffin in a mass ratio of 1:1. The mixture is fully melted and stirred in an oil bath at 70°C to 80°C to form a viscous white colloidal mixture.

[0107] The brazing slurry is applied to the treated nickel-based superalloy connection surface to be welded and the surface-modified carbon / carbon composite material connection surface, and the pyrolytic carbon-modified molybdenum-nickel foam is placed between the carbon / carbon composite material connection surface and the nickel-based superalloy connection surface to be welded coated with the brazing slurry, and compacted to form a sandwich structure. During the compaction process, the two parent materials to be welded with the brazing slurry are placed opposite to each other and squeezed against each other, so that the excess brazing material between the carbon / carbon composite material and the nickel-based superalloy flows out, and the two are tightly connected. The excess brazing material is scraped off with a scraper, and the nickel-based superalloy is placed on the carbon / carbon composite material. The metal's own gravity is used to form a tight physical connection between the carbon / carbon composite material and the nickel-based superalloy through the brazing layer. Among them, the thickness of the brazing slurry is 300μm.

[0108] The sandwich structure was placed under vacuum conditions, heated to 900°C at a heating rate of 11°C / min, kept warm for 30 minutes, and then cooled to 600°C at a rate of 4°C / min to complete the brazing connection between the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0109] See also Figure 5 and Figure 6 The surface morphology of the brazed joint and coating obtained in Example 2 and Comparative Example 2 was compared and tested. The results showed that after long-term high-temperature heat treatment, the coating of Example 2 had a high degree of densification, and the fusion of Mo and Si was complete at high temperature. The Mo-Si coating was evenly distributed in a spherical shape on the surface of the SiC coating, the coating thickness was uniform, and the bonding interface between the coating and the SiC substrate was relatively flat without obvious cracks. The Mo-Si coating has fewer pores in the interface area close to the SiC side, indicating that the particles in this area have been partially densified during the sintering process, which plays a positive role in improving the interface bonding. While physically bonding through mechanical bite, during the high-temperature sintering process at 1500°C, accompanied by local diffusion bonding and chemical reactions, the interface bonding strength is further enhanced. After the carbon / carbon composite material modified by the composite coating is connected to the nickel-based high-temperature alloy GH3230, the Mo-Si coating diffuses inside the brazing material layer under high temperature, and the base material and the brazing material are bonded by the diffusion of Si atoms, and Mo atoms enter the Ni ss The joint strength is enhanced by forming high-strength and compound by solid solution. However, in comparative example 2, after a short-term heat treatment at 1200°C, the Mo-Si coating has not yet formed a tight bond with the SiC coating substrate. The Mo-Si coating is accumulated on the substrate surface in a granular form, and the surface is rough, the density is low, and the coating has many pores. After the carbon / carbon composite material modified by this process is brazed with the nickel-based high-temperature alloy GH3230, many holes appear at the interface between the coating and the brazing material and inside the foreground. When the coating and brazing material with low density fail to fill the holes at high temperature, defects will occur at the interface, thereby reducing the joint strength.

[0110] Example 3 First, Si powder, C powder and Al2O3 were weighed separately in a mass ratio of 70:25:5 using an electronic balance, and manually stirred in a mortar for 3 hours. Then, a planetary ball mill was used to mix the mixture for more than 24 hours. Finally, the mixture was sieved and manually stirred in a mortar for 3 hours, and dried in a 373K oven for at least 5 hours to obtain a mixed powder for use.

[0111] The carbon / carbon composite material and the nickel-based high-temperature alloy are processed into 15mm×10mm×4mm base materials by wire cutting machine for later use.

[0112] The carbon / carbon composite material connection surface was polished using 600-grit silicon carbide sandpaper to ensure that the surface roughness and roughness of the carbon / carbon composite material connection surface were consistent. The polished carbon / carbon composite material was ultrasonically cleaned in anhydrous ethanol to remove the surface carbon powder, and dried to complete the surface pretreatment.

[0113] Line the inner wall of the graphite crucible with graphite paper, then spread the mixed powder on the bottom of the crucible, and then place the carbon / carbon sample on top of it, followed by spreading the mixed powder until the sample is fully buried, and finally place a layer of graphite paper and carbon felt on the top of the buried powder in sequence, spread a layer of C powder on the carbon felt, cover it with graphite paper and seal it.

[0114] Place the graphite crucible in an ultra-high temperature graphite heating furnace, then evacuate and maintain the pressure for 10 minutes. After checking that the airtightness is normal, introduce Ar gas to normal pressure. After checking that the cooling water is normal, set the temperature control program to start heating. The heating furnace is heated to 2100℃ and maintained for 1 hour.

[0115] After the insulation is completed, the graphite heating furnace is slowly cooled to room temperature according to the cooling program, and then the graphite crucible is taken out of the heating furnace and the treated sample is taken out of the crucible, the residual powder on the surface is removed, and then it is cleaned and dried to obtain the SiC coating modified base material.

[0116] The prepared SiC coating modified base material was ultrasonically cleaned in anhydrous ethanol for 20 minutes and placed in an oven for drying.

[0117] The Mo powder and Si powder were evenly mixed by ball milling for 24 hours in a ratio of 30:70 by mass to obtain a Mo-Si mixed powder; Anhydrous ethanol, PVB, NaF powder, and Mo-Si mixed powder were weighed in order according to the mass ratio of 50%, 0.5%, 0.5%, and 49% to prepare a slurry, and then the slurry was stirred evenly with a magnetic stirrer for later use; The prepared Mo-Si slurry is evenly applied on the surface of the SiC coating modified base material, and then placed in an oven for drying to obtain a SiC-Mo-Si modified carbon / carbon composite material for standby use.

[0118] The coated and dried samples are placed in a high-temperature tubular furnace and heat treated in a protective atmosphere. The specific process is as follows: the dried SiC-Mo-Si modified carbon / carbon composite material is placed in a corundum crucible, and then the crucible is placed in the tubular furnace; the tubular furnace is locked and sealed, evacuated and maintained in vacuum for 2 hours, and after checking to make sure that the equipment is airtight, Ar gas is slowly passed to normal pressure; the furnace temperature is raised to 2000°C at a heating rate of 5K / min, and kept warm for 2 hours; after the insulation is completed, the tubular furnace is cooled to room temperature at a cooling rate of 10K / min, and finally the Ar gas is turned off, the locking valve is disassembled and the crucible is taken out to obtain the SiC-Mo-Si composite coating modified carbon / carbon composite material, thereby completing the modification of the carbon / carbon composite material.

[0119] Use 180-mesh and 600-mesh sandpaper to grind the connection surfaces of the nickel-based high-temperature alloy in turn to remove the surface oxide scale and corrosion layer; The polished nickel-based high-temperature alloy is ultrasonically cleaned in anhydrous ethanol to remove surface metal powder, and then dried to complete the surface treatment to obtain the nickel-based high-temperature alloy after the surface treatment.

[0120] The nickel-based solder is added to a binder to make it into a paste slurry. The binder is a mixture of vaseline and liquid paraffin in a mass ratio of 1:1. The mixture is fully melted and stirred in an oil bath at 80° C. to form a viscous white colloidal mixture.

[0121] The brazing slurry is applied to the treated nickel-based superalloy connection surface to be welded and the surface-modified carbon / carbon composite material connection surface, and the pyrolytic carbon-modified molybdenum-nickel foam is placed between the carbon / carbon composite material connection surface and the nickel-based superalloy connection surface to be welded coated with the brazing slurry, and compacted to form a sandwich structure. During the compaction process, the two parent materials to be welded with the brazing slurry are placed opposite to each other and squeezed against each other, so that the excess brazing material between the carbon / carbon composite material and the nickel-based superalloy flows out, and the two are tightly connected. The excess brazing material is scraped off with a scraper, and the nickel-based superalloy is placed on the carbon / carbon composite material. The metal's own gravity is used to form a tight physical connection between the carbon / carbon composite material and the nickel-based superalloy through the brazing layer. Among them, the thickness of the brazing slurry is 300μm.

[0122] The sandwich structure was placed under vacuum conditions, heated to 1200°C at a heating rate of 10°C / min, kept warm for 10 minutes, and then cooled to 600°C at a rate of 3°C / min to complete the brazing connection between the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0123] Comparative Example 3 First, Si powder, C powder and Al2O3 were weighed separately in a mass ratio of 70:25:5 using an electronic balance, and manually stirred in a mortar for 3 hours. Then, a planetary ball mill was used to mix the mixture for more than 24 hours. Finally, the mixture was sieved and manually stirred in a mortar for 3 hours, and dried in a 373K oven for at least 5 hours to obtain a mixed powder for use.

[0124] The carbon / carbon composite material and the nickel-based high-temperature alloy are processed into 15mm×10mm×4mm base materials by wire cutting machine for later use.

[0125] The carbon / carbon composite material connection surface was polished using 600-grit silicon carbide sandpaper to ensure that the surface roughness and roughness of the carbon / carbon composite material connection surface were consistent. The polished carbon / carbon composite material was ultrasonically cleaned in anhydrous ethanol to remove the surface carbon powder, and dried to complete the surface pretreatment.

[0126] Line the inner wall of the graphite crucible with graphite paper, then spread the mixed powder on the bottom of the crucible, and then place the carbon / carbon sample on top of it, followed by spreading the mixed powder until the sample is fully buried, and finally place a layer of graphite paper and carbon felt on the top of the buried powder in sequence, spread a layer of C powder on the carbon felt, cover it with graphite paper and seal it.

[0127] Put the graphite crucible into the ultra-high temperature graphite heating furnace, then evacuate and maintain the pressure for 10 minutes to check if the airtightness is normal, then introduce Ar gas to normal pressure, check that the cooling water is normal, set the temperature control program to start heating, and heat the heating furnace to 2100℃ and keep it for 1 hour.

[0128] After the insulation is completed, the graphite heating furnace is slowly cooled to room temperature according to the cooling program, and then the graphite crucible is taken out of the heating furnace and the treated sample is taken out of the crucible, the residual powder on the surface is removed, and then it is cleaned and dried to obtain the SiC coating modified base material.

[0129] The prepared SiC coating modified base material was ultrasonically cleaned in anhydrous ethanol for 20 minutes and placed in an oven for drying.

[0130] The Mo powder and Si powder were evenly mixed by ball milling for 24 hours in a ratio of 20:80 by mass to obtain a Mo-Si mixed powder; Anhydrous ethanol, PVB, NaF powder, and Mo-Si mixed powder were weighed in order according to the mass percentages of 50%, 0.5%, 0.5%, and 49% to prepare a slurry, and then the slurry was stirred evenly with a magnetic stirrer for later use; Use the prepared slurry to evenly apply the slurry on the surface of the SiC coating modified base material, and then put it in an oven to dry for use.

[0131] The coated and dried samples are placed in a high-temperature tubular furnace for heat treatment in a protective atmosphere. The specific process is as follows: the dried SiC-Mo-Si modified carbon / carbon composite material is placed in a corundum crucible, and then the crucible is placed in the tubular furnace; the tubular furnace is locked and sealed, evacuated and maintained for 2 hours, and after checking to make sure that the equipment is airtight, Ar gas is slowly passed to normal pressure; ③ the furnace temperature is raised to 2000°C at a heating rate of 5K / min, and kept warm for 2 hours; ④ after the insulation is completed, the tubular furnace is cooled to room temperature at a cooling rate of 10K / min, and finally the Ar gas is turned off, the locking valve is disassembled and the crucible is taken out to obtain the SiC-Mo-Si composite coating modified carbon / carbon composite material Use 180-mesh and 600-mesh sandpaper to grind the connection surfaces of the nickel-based high-temperature alloy in turn to remove the surface oxide scale and corrosion layer; The polished nickel-based high-temperature alloy is ultrasonically cleaned in anhydrous ethanol to remove surface metal powder, and then dried to complete the surface treatment to obtain the nickel-based high-temperature alloy after the surface treatment.

[0132] The nickel-based solder is added to a binder to make it into a paste slurry. The binder is a mixture of vaseline and liquid paraffin in a mass ratio of 1:1. The mixture is fully melted and stirred in an oil bath at 80° C. to form a viscous white colloidal mixture.

[0133] The brazing slurry is applied to the treated nickel-based superalloy connection surface to be welded and the surface-modified carbon / carbon composite material connection surface, and the pyrolytic carbon-modified molybdenum-nickel foam is placed between the carbon / carbon composite material connection surface and the nickel-based superalloy connection surface to be welded coated with the brazing slurry, and compacted to form a sandwich structure. During the compaction process, the two parent materials to be welded with the brazing slurry are placed opposite to each other and squeezed against each other, so that the excess brazing material between the carbon / carbon composite material and the nickel-based superalloy flows out, and the two are tightly connected. The excess brazing material is scraped off with a scraper, and the nickel-based superalloy is placed on the carbon / carbon composite material. The metal's own gravity is used to form a tight physical connection between the carbon / carbon composite material and the nickel-based superalloy through the brazing layer. Among them, the thickness of the brazing slurry is 300μm.

[0134] The sandwich structure was placed under vacuum conditions, heated to 1200°C at a heating rate of 10°C / min, kept warm for 10 minutes, and then cooled to 600°C at a rate of 3°C / min to complete the brazing connection between the carbon / carbon composite material and the nickel-based high-temperature alloy.

[0135] See also Figure 7 and Figure 8The surface morphology of the brazed joint and coating obtained in Example 3 and Comparative Example 3 was compared and tested. The results showed that after the composite coating made of Mo-Si powder in an appropriate proportion was introduced into the joint, the phase distribution of the middle layer inside the joint was uniform, and the alternating distribution of the plastic phase and the toughness phase increased the ability of the middle layer to relieve thermal stress. The cracks can be deflected between phases with different hardnesses, thereby consuming energy and reducing the possibility of joint cracking. When the coating prepared by the process used in Comparative Example 3, due to the low proportion of Mo powder, the proportion of Si atoms on the coating surface is too high, and the content of Mo atoms is relatively low, after the carbon / carbon composite material modified by the coating is connected to GH3230, at high temperature, the brazing material reacts with the SiC surface to form a metallized bonding layer, through the diffusion of Si elements and Ni-Si compounds and Si-rich Ni ss The formation of solid solution constitutes a chemical bonding layer. The free Si element can reduce the interfacial energy of the SiC surface, promote the wettability of the brazing material at high temperature, and help it penetrate into the tiny pores of the porous coating. However, due to the presence of impurities or uneven roughness on the surface of the Mo-Si coating, some areas have defects such as holes. The phase distribution area of ​​the brazing intermediate layer does not have too much Mo element participation, and Mo-richNi cannot be formed. ss Zone 3 is the transition layer between metal and brazing material, which is mainly composed of lath-shaped and needle-shaped Cr ss phase is evenly distributed in Si-rich Ni ss On the matrix, it can be seen that the appropriate powder ratio is also the main factor affecting the combination between the two.

[0136] In summary, the present invention provides a carbon / carbon composite material, a modification method and a nickel-based high-temperature alloy brazing method thereof. The method uses a slurry spraying process to prepare a Mo-Si coating on the basis of embedding a SiC coating, and forms a SiC-MoSi2 composite coating by curing through high-temperature heat treatment. The presence of the SiC-MoSi2 composite coating not only provides a CTE transition layer for the joint, reduces the residual stress caused by the difference in thermal expansion, but also creates conditions for the generation of Mo-based compounds. The strength of the joint modified by the SiC-MoSi2 composite coating reaches 26.34 MPa, which is 70% higher than that of the unmodified joint. The SiC-MoSi2 composite coating can not only improve the wettability and interface bonding strength of the brazing material and the base material, but also optimize the base material interface reaction to form a uniform and continuous brazing layer, thereby making the brazing connection stronger and more stable, and more suitable for large-sized component connections and service under high temperature conditions.

[0137] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A method for modifying a carbon / carbon composite material, characterized in that: include: The carbon / carbon composite material is embedded by Si powder, C powder and Al2O3 to prepare a SiC coating modified base material; wherein the mass ratio of the Si powder, C powder and Al2O3 is (40-70): (20-50): (5-10); The SiC coating modified parent material is sprayed with Mo-Si slurry to obtain a SiC-Mo-Si modified carbon / carbon composite material; wherein, by mass percentage, the Mo-Si slurry comprises 44% to 54% of anhydrous ethanol, 0.5% of PVB, 0.5% of NaF powder and 45% to 55% of Mo-Si mixed powder, the Mo-Si mixed powder comprises Mo powder and Si powder, and the mass ratio of the Mo powder to the Si powder is (30 to 50): (50 to 70); The SiC-Mo-Si modified carbon / carbon composite material is heat treated and cured to obtain a modified carbon / carbon composite material, thereby completing the modification of the carbon / carbon composite material.

2. The carbon / carbon composite material modification method according to claim 1, characterized in that: The method for preparing a SiC coating modified parent material by embedding the carbon / carbon composite material with Si powder, C powder and Al2O3 is as follows: Mix Si powder, C powder and Al2O3 evenly, and dry to obtain a mixed powder; Performing surface treatment on the carbon / carbon composite material connection surface to obtain a surface-treated carbon / carbon composite material; The surface treated carbon / carbon composite material is buried in the mixed powder, and is sealed, vacuum heated, cooled, the residual powder on the surface is removed, cleaned and dried in sequence to obtain a SiC coating modified base material.

3. The carbon / carbon composite material modification method according to claim 2, characterized in that: The vacuum heating temperature is 1500° C. to 2100° C., and the time is 1 to 3 hours.

4. The method for modifying a carbon / carbon composite material according to claim 1, characterized in that: The method of spraying the SiC coating modified parent material with Mo-Si slurry to obtain the SiC-Mo-Si modified carbon / carbon composite material is: The SiC coating modified base material is placed in anhydrous ethanol for cleaning and drying to obtain a cleaned SiC coating modified base material; Prepare Mo-Si slurry; The Mo-Si slurry is sprayed onto the cleaned surface of the SiC coating modified parent material, and dried to obtain a SiC-Mo-Si modified carbon / carbon composite material.

5. The method for modifying a carbon / carbon composite material according to claim 1, characterized in that: The temperature of the heat treatment curing is 1500° C. to 2000° C., and the heat preservation time is 2 to 4 hours.

6. A carbon / carbon composite material, characterized in that: The modification is carried out using the modification method described in any one of claims 1 to 5.

7. A method for brazing the carbon / carbon composite material according to claim 6 and a nickel-based high-temperature alloy, characterized in that: include: Performing surface treatment on the nickel-based high-temperature alloy to be welded to obtain the nickel-based high-temperature alloy after surface treatment; Prepare brazing slurry; The brazing slurry is applied to the connection surface of the modified carbon / carbon composite material and the connection surface of the nickel-based high-temperature alloy after surface treatment, and compacted to form a sandwich structure; The sandwich structure is subjected to temperature-raising brazing to obtain a connecting piece of the carbon / carbon composite material and the nickel-based high-temperature alloy, thereby completing the brazing of the carbon / carbon composite material and the nickel-based high-temperature alloy.

8. The method for brazing a carbon / carbon composite material and a nickel-based high-temperature alloy according to claim 7, characterized in that: The thickness of the brazing slurry applied to the connection surface of the modified carbon / carbon composite material and the connection surface of the nickel-based high-temperature alloy after surface treatment is 100-300 μm.

9. The method for brazing a carbon / carbon composite material and a nickel-based high-temperature alloy according to claim 7, characterized in that: The brazing slurry is a paste slurry, comprising a nickel-based brazing filler metal and a binder; the binder comprises vaseline and liquid paraffin in a mass ratio of 1:

1.

10. The method for brazing a carbon / carbon composite material and a nickel-based high-temperature alloy according to claim 7, characterized in that: The sandwich structure is subjected to temperature-raising brazing to obtain a carbon / carbon composite material and a nickel-based high-temperature alloy connector. The brazing method of the carbon / carbon composite material and the nickel-based high-temperature alloy is as follows: The sandwich structure is heated to 900°C to 1200°C at a heating rate of 10°C / min to 11°C / min, kept warm for 10 to 30 minutes, and then cooled to 600°C at 3°C / min to 4°C / min to obtain a carbon / carbon composite material and a nickel-based high-temperature alloy connector, thereby completing the brazing of the carbon / carbon composite material and the nickel-based high-temperature alloy.

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