A method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals

Abstract

This invention relates to a method for synergistic brazing of carbon-based composite materials and metals using surface structure and micro-oxidation, belonging to the field of composite material joining technology. The method includes the following steps: constructing a microstructure array on the bonding surface of the carbon-based material; oxidizing the carbon-based material to form a porous structure; and brazing the carbon-based material and metal using a solder, with the liquid solder filling the microstructure array and porous structure, forming a mechanical interlocking structure and a continuous thermally conductive network at the interface, thus achieving synergistic brazing of the carbon-based composite material and the metal. This invention has advantages such as low interfacial thermal resistance, high bonding strength, high process efficiency, and wide applicability, and is suitable for aerospace thermal structures, high heat flux density thermal management structures, and high-temperature joining applications.

Description

Technical Field

[0001] This invention relates to a method for brazing carbon-based materials to metals, belonging to the field of composite material joining technology. Background Technology

[0002] Carbon-based composite materials (such as C) f C / C composite materials and C / SiC composite materials have the characteristics of low density, high specific strength, high temperature resistance, thermal shock resistance and excellent thermal stability, and are widely used in aerospace thermal protection structures, plasma-facing components of nuclear fusion devices, high-performance braking systems and high heat flux density thermal management structures.

[0003] In practical engineering applications, carbon-based composite materials are often connected to metal structural components to achieve complex structural assembly, heat transfer, and load transfer. Currently, active brazing is the primary method used to connect carbon-based composite materials to metals. However, due to the significant difference in thermal expansion coefficients between carbon-based composite materials and metals, large residual stresses are easily generated during the brazing cooling process, leading to joint cracking, interface failure, and reduced connection strength. Furthermore, traditional planar brazing interfaces suffer from limited contact area, insufficient solder wetting, and high interfacial thermal resistance, making it difficult to meet the application requirements for high thermal conductivity connections under high heat flux density conditions.

[0004] In existing technologies, researchers typically enhance mechanical interlocking through surface structure designs such as grooving and perforation to improve joint strength. This relies on the brachistochrone groove to alter the flow path and spreading behavior of the solder at the interface, without addressing interfacial thermal resistance control or the construction of a thermally conductive network. Alternatively, surface oxidation modification can be used to improve solder wettability and interfacial bonding, thereby reducing interfacial thermal resistance. However, most of these methods only address the mechanical or thermal conductivity of the joint individually, and research on the synergistic improvement of both mechanical and thermal conductivity is still limited.

[0005] Furthermore, traditional slow oxidation processes are prone to causing excessive oxidation damage to carbon fibers, making it difficult to precisely control the oxide layer depth, and the processing time is relatively long, which is not conducive to continuous industrial production. Therefore, it is of great significance to develop a brazing method that can simultaneously improve the connection strength and thermal conductivity of carbon-based composite materials and metal joints, while taking into account interface stability and process controllability.

[0006] Therefore, there is an urgent need to propose a method for synergistic brazing of carbon-based composite materials and metals based on surface structure and micro-oxidation to solve the above-mentioned technical problems. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of low connection strength, high interfacial thermal resistance, and poor thermal cycling stability in existing carbon-based composite material and metal brazed joints. It provides a method for synergistic brazing of surface structure and micro-oxidation between carbon-based composite materials and metals. A brief overview of this invention is provided below to offer a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0008] The technical solution of this invention: A method for synergistic brazing of carbon-based composite materials and metals based on surface structure and micro-oxidation includes the following steps: Step 1: Construct a microstructure array on the interface of carbon-based materials; Step 2: Oxidize the carbon-based material to form a porous structure; Step 3: Use carbon-based brazing filler material to braze the metal. The liquid brazing filler fills the microstructure array and pore structure, forming a mechanical interlocking structure and a continuous heat-conducting network at the interface, thereby achieving synergistic brazing of carbon-based composite materials and metal.

[0009] Preferably, in step 1, the carbon-based material is C. f / C composite material or C / SiC composite material; In step 3, the metal is a copper alloy, a nickel-based high-temperature alloy, or a titanium alloy; the solder is a MoCu-Cu-Ti active solder.

[0010] Preferably, in step 1, the microstructure array is a parallel groove array, a cross groove array, a gradient groove array, or a multi-scale composite groove array.

[0011] Preferably, the groove depth is 0.05–0.11 mm and the groove spacing is 0.25–0.40 mm.

[0012] Preferred: In step 2, the carbon-based material is placed in an ultrafast heating device and heated, kept warm, and cooled in an air atmosphere; the pyrolytic carbon on the surface of the carbon-based material is selectively removed, and a porous structure is formed around the carbon fibers.

[0013] Preferably, in step 2, the temperature is increased to 1000-1200 °C at a certain heating rate, held for 5-15 seconds, and then cooled to room temperature.

[0014] Preferably, in step 2, the pore size is 1–20 μm.

[0015] Preferably, in step 3, the active solder is placed between the treated carbon-based material and the metal; Apply welding pressure, heat up, hold at that temperature, and cool under vacuum conditions to obtain a brazed joint.

[0016] Preferably, in step 3, the Ti element content in the MoCu-Cu-Ti active solder is 1-10 wt%, and the thickness is 100-300 μm; The brazing temperature is 1000~1150℃.

[0017] Preferably, the annular pores can form capillary wetting channels during the brazing process to promote the filling of the groove and the carbon fiber by the active brazing filler metal; During the brazing process, the active element Ti reacts with the interface of the carbon-based composite material to form a TiC reaction layer; The continuous thermally conductive network includes the solder-filled region, the TiC reaction layer, and the heat transfer path formed between the carbon fibers.

[0018] The present invention has the following beneficial effects: 1. This invention combines surface groove array structure design with ultrafast heating micro-oxidation treatment to construct a multi-scale connection interface on the surface of carbon-based composite materials, which combines macroscopic groove structure with microscale annular pores; 2. The groove array structure can increase the filler metal space and interface contact area, improve the mechanical interlocking effect, and alleviate the residual stress caused by the difference in thermal expansion coefficient during the brazing cooling process; 3. Ultrafast heating micro-oxidation treatment can selectively remove pyrolytic carbon and form annular pore structure, thereby promoting the wetting and penetration of liquid active solder in the interface and improving the interface bonding quality; 4. Through the synergistic effect of macroscopic groove structure and microscale annular pore structure, the shear strength and thermal conductivity of brazed joints can be improved simultaneously; 5. Compared with the traditional slow oxidation process in a muffle furnace, the ultrafast heating micro-oxidation process of this invention has a shorter treatment time, controllable oxidation depth, and less damage to carbon fibers, making it suitable for continuous industrial production; 6. This invention applies to C f The connection between C / C composite materials and C / SiC composite materials and various metal materials such as copper alloys, nickel-based superalloys and titanium alloys has good versatility. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the surface groove array structure of the carbon-based composite material in this invention; Figure 2 This is a scanning electron microscope (SEM) schematic diagram of the annular pore structure formed after ultrafast heating and micro-oxidation in this invention. Figure 3 This is a schematic diagram of the microstructure of the brazed joint interface obtained in Embodiment 1 of the present invention; Figure 4 A comparison chart of joint shear strength and thermal conductivity under different processing techniques; Figure 5 This is a schematic diagram of the multi-scale interface collaborative reinforcement mechanism of the present invention; Figure 6 The images show the solder penetration pattern and EDS surface scan of Ti element in the annular pores.

[0020] In the figure, 1-groove array; 2-carbon fiber; 3-annular pores; 4-active solder layer; 5-metal substrate; 6-heat conduction path. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0022] Specific implementation method one: Combining Figure 1-6 This embodiment describes a method for synergistic brazing of the surface structure and micro-oxidation of a carbon-based composite material and a metal, comprising the following steps: Step 1: Construct a microstructure array on the carbon-based material surface to be joined; the groove array provides macroscopic heat transfer channels; Step 2: Selective micro-oxidation treatment is performed on the carbon-based material to form a capillary wetting pore structure around the carbon fibers; the annular pores promote the penetration of the solder into the carbon fibers. In addition to the macroscopic grooves, ultrafast micro-oxidation is used to selectively remove pyrolytic carbon, forming an annular pore structure around the carbon fibers. This allows the liquid active solder to further penetrate into the surrounding fibers, forming: Microscale capillary wetting channels, three-dimensional continuous brazing filler metal network, and fiber-level interface anchoring structure; This method not only alters the "surface flow behavior" of the solder, but also changes the "interfacial penetration and microstructure construction mechanism" of the solder at the fiber scale. Step 3: The treated carbon-based material and the metal are brazed together using a solder. The liquid solder simultaneously fills the microstructure array and the capillary wetting pore structure. The active solder forms a continuous filling region inside the pores, thereby forming a mechanically interlocked structure and a continuous thermally conductive network at the interface (the interface between the metal and the carbon-based material), achieving a synergistic improvement in the mechanical and thermal properties of the joint. The core of this invention is not simply surface structure optimization or simple oxidation modification, but rather the in-situ construction of a capillary network around the carbon fiber that can be actively wetted by the liquid solder. By utilizing the coupling effect between the macroscopic structure and the microscale wetting behavior, a cross-scale continuous thermally conductive connection interface is formed. Therefore, this invention not only changes the solder flow path, but also changes the interface reaction behavior, heat flow transfer mode, and interface structure evolution mechanism, constructing a three-dimensional thermally conductive network that runs through the interface. This can significantly reduce the interface thermal resistance and improve the thermal conductivity under high heat flow conditions, thereby achieving a thermo-mechanical synergistic strengthening of the interface between the carbon-based composite material and the dissimilar metal. It is not just a simple increase in shear strength, but a synergistic improvement in both mechanical and thermal properties.

[0023] Specific Implementation Method Two: Combining Figure 1-6 This embodiment describes a method for synergistic brazing of the surface structure and micro-oxidation of a carbon-based composite material and a metal. In step 1, the carbon-based material is a carbon-based composite material, such as C... f / C composite material or C / SiC composite material; In step 3, the metal is a copper alloy, a nickel-based high-temperature alloy, or a titanium alloy; the solder is an active solder, such as MoCu-Cu-Ti active solder.

[0024] Specific implementation method three: Combining Figure 1-6 This embodiment describes a method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals. In step 1, an electric discharge wire cutting device is used to process a parallel groove array on the surface of the carbon-based material to be joined; the surface is then ultrasonically cleaned with anhydrous ethanol for 15 minutes and dried. The microstructure array is any one of a parallel groove array, a cross groove array, a gradient groove array, or a multi-scale composite groove array.

[0025] Specific implementation method four: Combination Figure 1-6 This embodiment describes a method for synergistic brazing of the surface structure and micro-oxidation of a carbon-based composite material and a metal, wherein the groove depth is 0.05–0.11 mm and the groove spacing is 0.25–0.40 mm.

[0026] Specific Implementation Method Five: Combining Figure 1-6This embodiment describes a method for synergistic brazing of carbon-based composite materials and metals based on surface structure and micro-oxidation. In step 2, the processed carbon-based material is placed in an ultrafast heating device and heated, kept warm, and cooled in an air atmosphere. After ultrafast heating and micro-oxidation treatment, the pyrolytic carbon on the surface of the carbon-based material is selectively removed, and an annular pore structure is formed around the carbon fibers. The capillary wetting pores can form capillary driven channels during the brazing process to promote the penetration of liquid active brazing filler metal into the vicinity of the carbon fibers.

[0027] Specific Implementation Method Six: Combination Figure 1-6 This embodiment describes a method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals. In step 2, the ultrafast heating device is an infrared heating furnace, a laser heating device, or a plasma rapid heating device. The device heats the material to 1000-1200°C at a certain heating rate (e.g., 100°C / s), holds it at that temperature for 5-15 seconds, and then cools it to room temperature at 150°C / s. This invention employs rapid heating at 50–200 °C / s, second-level heat preservation, and rapid cooling at over 100 °C / s. Its purpose is not ordinary oxidation, but rather to selectively remove pyrolytic carbon while avoiding excessive damage to the carbon fibers. Therefore, it can precisely control the pore depth, reduce fiber damage, maintain the overall strength of the composite material, and improve interface stability. In contrast, existing technologies mostly involve structural processing and do not address the selective oxidation of pyrolytic carbon, the formation of pores around the fibers, microstructure control, or rapid heat treatment mechanisms.

[0028] Specific implementation method seven: Combining Figure 1-6 This embodiment describes a method for synergistic brazing of the surface structure and micro-oxidation of a carbon-based composite material and a metal. In step 2, the pore size of the annular pores is 1-20 μm, and the capillary wetting pores are distributed continuously or semi-continuously around the carbon fiber. This invention not only enhances brazing flux flow and mechanical interlocking through surface groove structures, but also further constructs microscale annular pore structures in situ around carbon fibers through ultrafast heating micro-oxidation, thereby forming a multi-scale interface connection system with synergistic effects of "macro-grooves and micro-pores". Although existing technologies improve the brazing performance of dissimilar materials through surface grooves, their technical approach remains at the level of interface geometry control, without providing technical inspiration for forming annular pore structures around carbon fibers through ultrafast micro-oxidation, and further constructing microscale capillary wetting networks and three-dimensional heat conduction channels. This invention is not a simple replacement or parameter optimization of existing groove structures, but rather achieves synergistic enhancement of interface wetting, mechanical interlocking, and heat conduction network construction based on the microstructure control of carbon-based composite material interfaces.

[0029] Specific implementation method eight: Combination Figure 1-6This embodiment describes a method for synergistic brazing of the surface structure and micro-oxidation of a carbon-based composite material and a metal. In step 3, a MoCu-Cu-Ti active brazing filler metal is placed between the treated carbon-based material connection surface and the metal. Apply a welding pressure of 1 kPa and place the furnace in a vacuum brazing furnace with a vacuum level better than 5 × 10⁻⁶ kPa. -4 Under Pa conditions, the temperature is increased to 1000-1150 °C at 10 °C / min, held for 10 min, and then cooled to room temperature in the furnace to obtain the brazed joint. This invention constructs a groove array structure on the surface of a carbon-based composite material and combines it with ultrafast heating micro-oxidation treatment to form a microscale annular pore structure inside the grooves and around the carbon fibers. This promotes the wetting and filling of the active solder in the interface, thereby forming a multi-scale connection interface that combines mechanical interlocking and low thermal resistance heat transfer channels, achieving a synergistic improvement in joint connection strength and thermal conductivity.

[0030] Specific Implementation Method Nine: Combining Figure 1-6 This embodiment describes a method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals. In step 3, the Ti element content in the MoCu-Cu-Ti active brazing filler metal is 1-10 wt%, and the thickness is 100-300 μm. The brazing temperature is 1000–1150 ℃; Through ultrafast micro-oxidation: selectively oxidizing and pyrolyzing carbon while retaining the carbon fiber matrix, continuous or semi-continuous annular pores are formed around the fiber, achieving "fiber / matrix interface microstructure reconstruction"; this process is not simply a mechanical processing of the structure, but more importantly, the evolution of the internal microstructure of the carbon-based composite material. Through surface structure design, carbon fiber interface modification, and control of solder penetration behavior, the three are synergistically achieved.

[0031] Specific Implementation Method Ten: Combining Figure 1-6 This embodiment describes a method for synergistic brazing of carbon-based composite materials and metal surface structures with micro-oxidation. The annular pores can form capillary wetting channels during the brazing process to promote the filling of active brazing filler metal into the groove and around the carbon fiber. During the brazing process, the active element Ti reacts with the interface of the carbon-based composite material to form a TiC reaction layer; The continuous thermally conductive network includes the solder-filled region, the TiC reaction layer, and the heat transfer path formed between the carbon fibers; Analysis of the synergistic reinforcement effect between the carbon-based composite material and the metal brazed by the aforementioned welding method: The study verified a significant synergistic strengthening effect between the surface groove structure and ultrafast heating micro-oxidation treatment in the synergistic brazing of carbon-based composite materials and metals, and introduced a synergistic strengthening factor η: η=Δσ synergy / (Δσ groove+Δσ oxidation) Wherein: Δσsynergistic is the intensity increment after synergistic treatment; Δσgroove is the intensity increment after individual groove treatment; Δσoxidation is the intensity increment after individual oxidation treatment.

[0032] Based on the embodiments and comparative example data: Original joint strength: 23.8 MPa; Strength after single-groove treatment: 25.4 MPa; Strength after single oxidation treatment: 24.2 MPa; Strength after co-treatment: 27.9 MPa.

[0033] but: Δσ_groove = 1.6 MPa; Δσ oxidation = 0.4 MPa; Δσ_cooperation = 4.1 MPa.

[0034] The calculation yields: η = 4.1 / (1.6 + 0.4) = 2.05 The results show that the strengthening effect of the synergistic treatment of the present invention is significantly higher than the linear superposition results of individual structural strengthening and individual oxidation strengthening, indicating that the present invention forms a nonlinear synergistic strengthening mechanism.

[0035] Synergistic reinforcement mechanism analysis: In this invention, after ultrafast heating and micro-oxidation treatment, a continuous or semi-continuous annular pore structure is formed around the carbon fiber. Because the formed pore size is much smaller than the macroscopic groove size, a higher capillary driving force can be generated during brazing. The capillary pressure satisfies the following relationship: P c =2γcosθ / r Where: P c γ is the capillary pressure; γ is the surface tension of the liquid solder; θ is the wetting angle; and r is the equivalent radius of the capillary pores.

[0036] Because the pore size of the annular pores is on the micrometer scale, r is significantly reduced. Therefore, the liquid active solder preferentially penetrates and fills the area around the carbon fiber under capillary pressure, thereby improving the interface wetting ability and interface density. Unlike existing technologies that only improve solder spreading behavior through macroscopic grooves, this invention achieves active penetration of liquid solder into the carbon fiber interface through a microscale capillary wetting mechanism.

[0037] During vacuum brazing, the Ti element in the MoCu-Cu-Ti active brazing filler metal diffuses towards the carbon-based composite material and reacts with the carbon fiber surface to form a TiC reaction layer. Ti + C → TiC The formed TiC interfacial reaction layer can: improve the chemical bonding between the solder and the carbon-based composite material; reduce the interfacial thermal resistance; improve the interfacial thermal stability; and improve the joint's resistance to thermal cycling failure. Simultaneously, because the annular pore structure enhances the penetration of liquid solder into the carbon fiber, it increases the contact area between Ti and the carbon fiber, thereby promoting the continuous formation of the interfacial reaction layer.

[0038] The cross-scale heat conduction network formation mechanism in this invention involves: a macroscopic groove array forming a 100-micron-scale main filling channel for the solder; annular pores formed by micro-oxidation forming a micron-scale capillary wetting network; a continuous metal coating layer formed by liquid active solder around the carbon fibers; and a TiC reaction layer further improving the continuity of interfacial heat transfer. Therefore, a continuous cross-scale heat conduction path of "metal—solder—TiC reaction layer—carbon fiber" is formed at the interface. Compared with traditional planar brazing interfaces, the heat flow in this invention is no longer limited to a two-dimensional planar diffusion mode, but forms a three-dimensional heat transfer network, thereby significantly reducing interfacial thermal resistance and improving thermal conductivity stability under high heat flux density conditions.

[0039] In this invention, the groove array structure increases the filler metal space and interfacial contact area, forming a mechanical interlocking structure, thereby improving the joint's shear resistance. The ultrafast heating micro-oxidation treatment selectively removes pyrolytic carbon, forming an annular pore structure around the carbon fibers. This annular pore structure facilitates the penetration of liquid active brazing filler metal into the carbon fibers, improving interfacial wettability and density. Simultaneously, the continuous filler metal filling region formed within the annular pores can construct a three-dimensional heat-conducting channel, thereby reducing interfacial thermal resistance. Therefore, through the synergistic effect of the groove array structure and the microscale annular pore structure, a synergistic improvement in the brazed joint's connection strength and thermal conductivity is achieved. The performance improvement obtained by this invention is significantly higher than the simple superposition result of a single groove structure treatment and a single oxidation treatment, indicating that the groove array structure and ultrafast heating micro-oxidation form a significant synergistic strengthening effect.

[0040] Example 1: The method for achieving synergistic enhancement of the thermodynamic properties of brazed carbon-based composite materials and metals based on surface structure design and micro-oxidation is carried out according to the following steps: 1. Using wire electrical discharge machining (EDM) equipment, at C f Parallel groove arrays are processed on the surface of the / C composite material to be joined; the groove depth is 0.09 mm and the groove spacing is 0.25 mm; after processing, the surface is ultrasonically cleaned with anhydrous ethanol for 15 min and then dried.

[0041] II. The processed C fThe C / C composite material was placed in an infrared ultrafast heating furnace and heated to 1200 °C at a heating rate of 100 °C / s in air atmosphere. After holding at that temperature for 10 s, it was cooled to room temperature at a rate of 150 °C / s. Following this ultrafast heating and micro-oxidation treatment, the C / C composite material... f The pyrolytic carbon on the surface of the / C composite material is selectively removed, forming an annular pore structure with a pore size of about 5 to 12 μm around the carbon fibers.

[0042] 3. Place a 300 μm thick MoCu-Cu-Ti active solder in the treated C f Between / C composite material and Haynes 230 nickel-based superalloy; wherein the Ti content is 5 wt%; a welding pressure of 1 kPa is applied and the material is placed in a vacuum brazing furnace with a vacuum degree better than 5 × 10⁻⁶ kPa. -4 Under Pa conditions, the temperature was increased to 1100 ℃ at 10 ℃ / min, held for 10 min, and then cooled to room temperature in the furnace to obtain the brazed joint.

[0043] Test results show that: The shear strength of the joint obtained in this embodiment is 27.9 MPa, which is 17.2% higher than that of the untreated joint; the thermal conductivity of the joint is 44.2–48.9 W / m·K at 600–900 °C, which is 22.4% higher than that of the untreated joint.

[0044] Example 2: The difference between this embodiment and Embodiment 1 is as follows: In step two, the ultrafast heating parameters are: heating rate 100 ℃ / s, heating temperature 1000 ℃, holding time 5 s, and cooling rate 200 ℃ / s; in step three, the brazing temperature is 1100 ℃, and the holding time is 10 min. The remaining steps are the same as in Embodiment 1.

[0045] Test results show that: The shear strength of the joint obtained in this embodiment is 26.5 MPa; the thermal conductivity of the joint is 41.6~45.3 W / m·K (600~900 ℃).

[0046] Example 3: The carbon-based composite material is a C / SiC composite material; the metallic material is Haynes 230 nickel-based superalloy; in step two, the heating temperature is 1000 ℃ and the holding time is 15 s; in step three, the brazing temperature is 1150 ℃ and the holding time is 20 min. The remaining steps are the same as in Example 1.

[0047] Test results show that: The shear strength of the joint obtained in this embodiment is 21.2 MPa; the thermal conductivity of the joint is 38.5~42.6 W / m·K (600~900 ℃).

[0048] Example 4: In step one, the groove depth is 0.09 mm and the groove spacing is 0.35 mm; in step two, the heating rate is 80℃ / s, the heating temperature is 900℃, and the holding time is 15 s; in step three, the brazing temperature is 1080℃, and the holding time is 5 min. The remaining steps are the same as in Example 1.

[0049] Test results show that: The shear strength of the joint obtained in this embodiment is 19.9 MPa; the thermal conductivity of the joint is 35.9~39.7 W / m·K (600~900 ℃).

[0050] The method of the present invention described in Examples 1-4 firstly uses wire electrical discharge machining (EDM) to process a groove array structure on the surface of a carbon-based composite material. Then, ultrafast heating micro-oxidation treatment is employed to selectively oxidize and remove the pyrolytic carbon on the surface of the carbon-based composite material, forming an annular pore structure around the carbon fibers. Subsequently, vacuum brazing is performed using a MoCu-Cu-Ti based active solder. This invention, through the synergistic effect of the macroscopic groove structure and the microscale annular pore structure, improves the wetting and filling ability of the active solder on the surface of the carbon-based composite material, while enhancing the interfacial mechanical interlocking effect and the continuity of the thermal conduction channel, thereby achieving a synergistic improvement in the connection strength and thermal conductivity between the carbon-based composite material and the metal joint. This invention has advantages such as low interfacial thermal resistance, high connection strength, high process efficiency, and wide applicability, and is suitable for aerospace thermal structures, high heat flux density thermal management structures, and high-temperature connections.

[0051] Comparative Example 1: Traditional planar brazing methods were used, without groove machining or micro-oxidation treatment. All other brazing parameters were the same as in Example 1.

[0052] Test results show that: The joint shear strength is 23.8 MPa; The thermal conductivity of the joint is 36.1–40.7 W / m·K (600–900 ℃).

[0053] Comparative Example 2: The groove array structure was machined using only wire electrical discharge machining, without ultrafast heating micro-oxidation treatment. All other parameters were the same as in Example 1.

[0054] Test results show that: The joint shear strength is 25.4 MPa; The thermal conductivity of the joint is 42.3–46.6 W / m·K (600–900 ℃).

[0055] Comparative Example 3: Only conventional muffle furnace oxidation treatment was performed, without the groove array processing. The oxidation process involved holding at 650 °C for 2 minutes in air. All other parameters were the same as in Example 1.

[0056] Test results show that: The joint shear strength is 24.2 MPa; the joint thermal conductivity is 38.9–41.2 W / m·K (600–900 ℃).

[0057] Existing technologies typically improve the spreading behavior of liquid solder at dissimilar material interfaces by processing regular groove structures, and their enhancement mechanisms mainly focus on: Increase the brazing filler metal spreading speed; increase the interface contact area; improve the mechanical interlocking effect; and alleviate local residual stress concentration.

[0058] However, existing technologies still focus on optimizing a single macroscopic geometric structure, without addressing the microscopic organization and control of carbon-based composite materials, nor forming a cross-scale thermally conductive network. In contrast, this invention not only constructs a groove array structure on the surface of the carbon-based composite material, but also combines ultrafast heating micro-oxidation treatment to form an annular capillary pore structure around the carbon fibers, thereby creating a synergistic connection system of "macroscopic structure—microscopic wetting—interfacial reaction—thermally conductive network".

[0059] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals, characterized in that: Includes the following steps: Step 1: Construct a microstructure array on the interface of carbon-based materials; Step 2: Oxidize the carbon-based material to form a porous structure; Step 3: Use brazing filler metal to braze carbon-based materials and metals, with liquid brazing filler metal filling the microstructure array and pore structure.

2. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 1, characterized in that: In step 1, the carbon-based material is C f / C composite material or C / SiC composite material; In step 3, the metal is a copper alloy, a nickel-based high-temperature alloy, or a titanium alloy; the solder is a MoCu-Cu-Ti active solder.

3. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 2, characterized in that: In step 1, the microstructure array is a parallel groove array, a cross groove array, a gradient groove array, or a multi-scale composite groove array.

4. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 3, characterized in that: The groove depth is 0.05–0.11 mm, and the groove spacing is 0.25–0.40 mm.

5. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 3, characterized in that: In step 2, the carbon-based material is placed in an ultrafast heating device and heated, kept warm, and cooled in an air atmosphere; the pyrolytic carbon on the surface of the carbon-based material is selectively removed, and a porous structure is formed around the carbon fibers.

6. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 5, characterized in that: In step 2, the temperature is increased to 1000-1200 °C at a certain heating rate, held for 5-15 seconds, and then cooled to room temperature.

7. A method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 5 or 6, characterized in that: In step 2, the pore size is 1–20 μm.

8. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 5, characterized in that: In step 3, the active solder is placed between the treated carbon-based material and the metal; Apply welding pressure, heat up, hold at that temperature, and cool under vacuum conditions to obtain a brazed joint.

9. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 8, characterized in that: In step 3, the Ti element content in the MoCu-Cu-Ti active solder is 1-10 wt%, and the thickness is 100-300 μm; The brazing temperature is 1000~1150℃.

10. The method for synergistic brazing of surface structure and micro-oxidation of carbon-based composite materials and metals according to claim 8, characterized in that: The annular pores can form capillary wetting channels during brazing, which can promote the filling of active brazing filler metal into the groove and around the carbon fiber. During the brazing process, the active element Ti reacts with the interface of the carbon-based composite material to form a TiC reaction layer; The continuous thermally conductive network includes the solder-filled region, the TiC reaction layer, and the heat transfer path formed between the carbon fibers.

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