A method for joining carbon materials using a high-entropy alloy solder

Abstract

The application provides a method for connecting carbon materials by using high-entropy alloy filler, and solves the technical problem that the structure obtained by the existing connecting method cannot meet the service requirement of ultrahigh temperature. The application is based on refractory high-entropy alloy of group IVB to group VI B, utilizes the advantages of high-entropy effect and discharge plasma connecting process, such as fast temperature rising speed, promoting element diffusion in the joint, controllable structure, etc., generates high-entropy carbide in the joint structure through the carbonization reaction of high-entropy alloy to realize the regulation and control of good high-temperature mechanical properties and high-temperature stability of the high-temperature carbon material joint, reduces the residual stress of the joint through the residual high-entropy alloy layer, thereby improves the strength and toughness of the joint and the strength of the joint at room temperature, and finally obtains a carbon material connecting joint with excellent comprehensive performance under high-temperature service condition.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, specifically relating to a method for connecting carbon materials using a novel high-entropy alloy brazing filler metal. Background Technology

[0002] Carbon-based materials such as graphite and C / C composites, due to their unique heat resistance and electrical / thermal properties, can be applied to a range of high-temperature and extreme environments, including aerospace and nuclear industries. For example, C / C composites, with their lightweight, low coefficient of linear expansion, high thermal and electrical conductivity, excellent thermal shock resistance, and wear resistance, have been widely used in the manufacture of aerospace structural components in recent years. However, due to limitations in the manufacturing process, directly fabricating large composite structures using C / C composites remains challenging and costly. Therefore, the engineering applications of these high-temperature carbon materials urgently require the fabrication of high-temperature resistant, high-strength, and high-toughness connecting joints.

[0003] Brazing is currently the main joining method for high-temperature carbon materials, and traditional brazing filler metals, primarily Cu-based, Ti-based, and Ag-based, are commonly used. For example, He et al. selected Ti... 14 Si 86 The eutectic alloy was successfully brazed using a pre-infiltration method to achieve a C / C composite joint. The resulting joint has a shear strength of up to 26 MPa at room temperature, and its theoretical service temperature is around 1000℃. It cannot be used in ultra-high temperature environments (ZJ He, C. Li , JL Qi, et al. Pre-infiltration and Brazing Behaviors of Cf / C Composites with High Temperature Ti-Si Eutectic Alloy. Carbon, 2018, 140:57-67.).

[0004] Chinese patent application CN 114346346 A discloses a method for brazing high-entropy carbide ceramics using a high-entropy alloy, specifically a method for joining (HfZrTiTaNb)C high-entropy carbide ceramics using a FeCoCrNiTix high-entropy alloy brazing filler metal. While the high-entropy alloy brazing filler metal in this method can avoid the formation of intermetallic compounds in the brazed joint, the reaction between the alloy brazing filler metal and the carbide ceramic base material leads to severe compositional segregation on the base material side. Furthermore, the presence of a large amount of low-melting-point alloy layer residue in the joint microstructure results in a service temperature of only 800°C. Brazed joints obtained at such low processing temperatures are clearly unsuitable for high-temperature carbon ceramics operating in ultra-high temperature environments.

[0005] It is evident that, currently, there is no suitable brazing alloy system or brazing technology for high-temperature carbon materials used in ultra-high temperature service environments. Therefore, it is necessary to further explore a method that can solve the current connection problems of high-temperature resistant carbon materials and their large structures. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problem that the structure obtained by the existing connection method cannot meet the requirements of ultra-high temperature service, and to provide a method for connecting carbon materials using a novel high-entropy alloy front brazing filler.

[0007] The concept of this invention:

[0008] Compared to traditional alloy brazing filler metals, high-entropy alloys possess characteristics such as high strength, high plasticity, and high fracture toughness. Refractory high-entropy alloys composed of elements from Groups IVB to VIB exhibit excellent high-temperature performance and good structural stability. However, the high melting point (typically above 1800℃) and poor element diffusion of refractory high-entropy alloys limit their development as brazing filler metals. With the deepening research on high-entropy alloys, research on high-entropy carbide ceramics has also progressed, currently focusing mainly on solid solutions of transition metals IVB and VB carbides. These carbides possess strong covalent bond characteristics and very high melting points, making them applicable under various extreme conditions. Considering the ultra-high temperature service environment of high-temperature carbon materials, the development of refractory high-entropy alloy brazing filler metals suitable for high-temperature resistant, high-strength, and tough carbon material bonding structures would be of great significance for high-temperature carbon materials. Therefore, this research team aims to explore suitable refractory high-entropy alloys from Groups IVB to VIB as brazing filler metals for the preparation of carbon material bonding structures.

[0009] Because refractory high-entropy alloys have high melting points (usually above 1800℃) and are difficult to diffuse, traditional heating methods, which typically have maximum temperatures below 1600℃, struggle to overcome this problem. Therefore, our research team proposes to use Spark Plasma Flash Joining (SPS Flash Joining), a novel rapid welding technology developed based on spark plasma sintering technology and basic brazing principles. Leveraging its characteristics of rapid heating, short joining time, high heating temperature, and controllable microstructure (and in SPS joining, the additional electric and magnetic fields can effectively reduce the joining temperature between ceramics, metals, and other materials, and accelerate material diffusion during the joining process, especially without damage or deformation), we have developed a spark plasma flash joining process suitable for this system. This is expected to solve the current bottleneck in joining high-temperature resistant carbon materials and their large structures.

[0010] To achieve the above objectives, the technical solution provided by this invention is:

[0011] The application of ZrHfNbTa or TiZrHfTa as solders in bonding carbon materials involves components with a molar percentage ranging from 15% to 35%. To maximize their high-entropy properties, an equimolar molar ratio of the components is preferred, i.e., Zr... 0.25 Hf 0.25 Nb 0.25 Ta 0.25 and Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 .

[0012] A type of solder is characterized by its composition of ZrHfNbTa or TiZrHfTa, with each component having a molar percentage ranging from 15% to 35%. To maximize its high-entropy characteristics, the preferred molar ratio of the components is an equimolar ratio, i.e., Zr... 0.25 Hf 0.25 Nb 0.25 Ta 0.25 and Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 .

[0013] A method for joining carbon materials using the aforementioned solder, characterized by the following steps:

[0014] 1) Preparation of high-entropy alloy brazing foil

[0015] Weigh the required pure metal according to the high-entropy alloy ratio, and prepare a high-entropy alloy brazing foil with a thickness of 150-200 μm;

[0016] 2) Connecting carbon materials

[0017] 2.1) Place the high-entropy alloy brazing foil obtained in step 1) between the welding surfaces of two pretreated carbon material blocks to be welded to form a "sandwich" structured welding assembly;

[0018] 2.2) Place the welded assembly obtained in step 2.1) in a spark plasma sintering furnace and apply pressure to the welded assembly to ensure full contact between the surfaces to be welded;

[0019] 2.3) Heat treatment of the samples to be welded can be performed in two ways:

[0020] The first method (rapid heating):

[0021] The spark plasma sintering furnace operates at full power and heats for 14-18 seconds. Within this time range, the temperature is heated to 2000℃~2300℃. After heating, the furnace is cooled, and the sample is cooled to below 50℃ within 3 minutes to complete the connection.

[0022] The second method (slow heating):

[0023] The sample to be welded is first heated to 1200-1400℃ at a heating rate of 20-60℃ / min, then heated to 1800℃-2200℃ at a rate of 20-40℃ / min, held at the target temperature for 10-60 min, and then cooled to room temperature at a rate of 50-100℃ / min to complete the connection. Considering both the processing efficiency and the impact of heating and cooling rates on the residual stress of the joint, the preferred heating rate is 50℃ / min, and the preferred cooling rate is 20℃ / min.

[0024] Furthermore, step 1) specifically involves:

[0025] 1.1) Weigh the required pure metal according to the high-entropy alloy ratio;

[0026] 1.2) After the weighed pure metals are mixed, they are melted multiple times by electric arc melting or electromagnetic melting under vacuum or inert atmosphere to obtain high-entropy alloy ingots.

[0027] 1.3) After the high-entropy alloy ingot has cooled to room temperature, it is taken out and rolled into a foil with a thickness of 300~500μm;

[0028] 1.4) After grinding, polishing and ultrasonic cleaning of the foil in sequence, a high-entropy alloy brazing foil with a thickness of 150-200 μm is obtained.

[0029] Further, in step 2.1), the pretreatment refers to grinding, polishing and ultrasonic cleaning the surface of the carbon material block to be welded in sequence;

[0030] In step 2.2), a pressure of 10–20 MPa is applied to the welded assembly to ensure good contact and conductivity between the samples to be welded; in the spark plasma sintering furnace, the pressure is less than 1 × 10⁻⁶ MPa. -3 Pa in a vacuum or inert atmosphere.

[0031] Furthermore, in step 2.3), in the first method, the heating rate is greater than 100℃ / s and the cooling rate is greater than 500℃ / min.

[0032] Furthermore, the carbon material is single-phase carbon or a carbon-based composite material.

[0033] Meanwhile, the present invention also provides a carbon material joint, which is special in that: the microstructure of the reaction layer of the joint prepared by the above method is a single high-entropy carbide ceramic or a high-entropy carbide and high-entropy alloy layer, and the joint has good metallurgical bonding.

[0034] Furthermore, it can be used in ultra-high temperature service environments above 1600℃.

[0035] Furthermore, it exhibits a shear strength of up to 27.3 MPa at 1600°C.

[0036] The principle of this invention:

[0037] Based on group IVB to VIB refractory high-entropy alloys, this invention comprehensively considers the physical properties, mechanical properties, oxidation resistance, and high-entropy carbide conversion capabilities of each constituent element. Two refractory high-entropy alloys, ZrHfNbTa and TiZrHfTa, were designed and prepared. Utilizing the advantages of high-entropy effect and the rapid heating rate, element diffusion promotion, and controllable microstructure of the spark plasma bonding process, high-entropy carbides are generated in the joint microstructure through the carbonization reaction of the high-entropy alloy. This achieves excellent high-temperature mechanical properties and high-temperature stability of the high-temperature carbon material joint. Simultaneously, the residual high-entropy alloy layer reduces residual stress in the joint, thereby improving the joint's toughness and strength at room temperature. Ultimately, a carbon material joint with excellent comprehensive performance under high-temperature service conditions is obtained.

[0038] The advantages of this invention are:

[0039] This invention proposes a method for joining high-temperature carbon materials using spark plasma welding to address the ultra-high temperature service environment of high-temperature carbon materials. This method employs rapid spark plasma heating, with a heating rate exceeding 100℃ / s and a cooling rate exceeding 500℃ / min, ensuring high efficiency in component production due to the extremely short processing time. When using a ZrHfNbTa high-entropy alloy as the solder to join C / C composite materials, the joint microstructure exhibits a single (ZrHfNbTa)C high-entropy carbide; when using a TiZrHfTa high-entropy alloy as the solder to join C / C composite materials, the joint microstructure exhibits a dual high-entropy microstructure of (TiZrHfTa)C high-entropy carbide + TiZrHfTa high-entropy alloy. In this method, if traditional slow discharge plasma heating is used, the sample is first heated to 1200~1400℃ at a heating rate of 50℃ / min, then heated to 1800℃~2200℃ at a rate of 20℃ / min, held at the target temperature for 10~60 min, and then cooled to room temperature at a rate of 50~100℃ / min. This allows the high-entropy alloy to fully react with the carbon material matrix. Using ZrHfNbTa and TiZrHfTa high-entropy alloys as solders to connect C / C composite materials, the joint microstructure exhibits a single high-entropy carbide structure of (ZrHfNbTa)C and (TiZrHfTa)C. The specific heating method used (rapid heating or slow heating) depends on the specific service environment and performance requirements of the joint.

[0040] The aforementioned joint structure exhibits excellent high-temperature strength and high-temperature oxidation resistance, and demonstrates good metallurgical bonding with the carbon material matrix. It retains a maximum shear strength of 27.3 MPa even at 1600℃. Furthermore, the ZrHfNbTa and TiZrHfTa high-entropy alloy foils are simple to prepare, have a wide joining process window, and are highly operable, showing excellent implementation prospects and suitability for the actual production of complex high-temperature carbon material components. Attached Figure Description

[0041] Figure 1 The microstructure of the prepared TiZrHfTa high-entropy alloy under scanning electron microscopy, EDS analysis results, and XRD pattern are shown.

[0042] Figure 2 The heating curve is shown for the SPS rapid connection process in Example 1.

[0043] Figure 3 The image shows the backscattered electron image of the graphite joint interface obtained in Example 1 under a scanning electron microscope.

[0044] Figure 4 The graphite joint interface obtained in Example 1 is shown in the EDS analysis results and the XRD analysis spectrum of the phase composition.

[0045] Figure 5The image shows the backscattered electron image and EDS elemental analysis results of the C / C composite joint interface obtained in Example 2 under a scanning electron microscope.

[0046] Figure 6 The image shows the backscattered electron image and EDS elemental analysis results of the graphite joint interface prepared in Example 3 under a scanning electron microscope.

[0047] Figure 7 The image shows the backscattered electron image and EDS elemental analysis results of the graphite joint interface obtained in Example 4 under a scanning electron microscope.

[0048] Figure 8 The image shows the backscattered electron image and EDS elemental analysis results of the graphite joint interface obtained in Example 5 under a scanning electron microscope. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0050] This invention relates to a method for joining carbon materials using a novel high-entropy alloy brazing filler metal, specifically comprising the following steps:

[0051] 1) Weigh the pure metal materials according to the proportions; mix the weighed pure metals and then melt them multiple times under vacuum or inert atmosphere using electric arc melting or electromagnetic melting to produce a high-entropy alloy ingot weighing about 0.6g; after the ingot cools to room temperature, take it out and roll it into a disc with a thickness of about 300~500 μm and a diameter of about 20 mm; after grinding, polishing and ultrasonic cleaning, the disc finally yields a high-entropy alloy brazing foil with a thickness of 150~200 μm;

[0052] 2) Grind, polish and ultrasonically clean the surfaces of two carbon material blocks with a diameter of 20 mm and a thickness of about 3 mm. Then, place the prepared high-entropy alloy foil between the two carbon material surfaces to be welded to form a "sandwich" structure welding assembly. Place the assembly into a spark plasma sintering (SPS) furnace. The pressure head in the SPS furnace is a graphite pressure head with a diameter of 20 mm, which is combined with the sample to be welded to form a good electrical and thermal conductor.

[0053] 3) Apply a pressure of 10–20 MPa between the samples to be welded to ensure good contact and conductivity between them; the SPS furnace can be a vacuum (pressure less than 1 × 10⁻⁶). -3 (Pa) or argon protective atmosphere;

[0054] 4) The following two different heating methods can be used: The first is rapid heating. The SPS furnace is operated at full power and a heating time of 14 to 18 seconds is applied to the sample to be welded. During this time, the sample to be welded will be heated to 2000℃ to 2300℃, with a heating rate of more than 100℃ / s. The molten high-entropy alloy and the carbon material base material undergo a violent carbonization reaction. After the heating process is completed, the sample is cooled with the furnace and cooled to below 50℃ within 3 minutes, with a cooling rate of more than 500℃ / min. The sample is then taken out.

[0055] The second heating method is the traditional SPS slow heating method. First, the sample is heated to 1200-1400℃ at a heating rate of 20-60℃ / min, then to 1800℃-2200℃ at a rate of 20-40℃ / min. Due to the slow heating rate, the high-entropy alloy is completely carbonized before reaching its melting point, thus the intermediate layer of the solder does not melt. The sample is then held at the target temperature for 10-60 minutes to allow sufficient diffusion between the high-entropy alloy and the carbon material base. Finally, the sample is cooled to room temperature at a rate of 50-100℃ / min before being removed.

[0056] The high-entropy alloy is ZrHfNbTa or TiZrHfTa, with each component having a molar percentage ranging from 15% to 35%. To maximize its high-entropy characteristics, the preferred molar ratio of the components is an equimolar ratio, i.e., Zr... 0.25 Hf 0.25 Nb 0.25 Ta 0.25 and Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 The carbon materials mentioned above can be single-phase carbon, such as graphite, or carbon-based composite materials.

[0057] To verify the bonding effect, the obtained carbon material joint component sample was radially cut to prepare a metallographic specimen. Under a scanning electron microscope, the joint was observed to be continuous and dense, without pores or cracks, indicating good metallurgical bonding. The high-entropy alloy exhibits obvious carbide reaction microstructure, which is either a single high-entropy carbide ceramic or a high-entropy carbide + high-entropy alloy layer microstructure, both of which are high-entropy solid solution phases. Even in an ultra-high temperature service environment of 1600℃, it still maintains a maximum shear strength of 27.3 MPa.

[0058] The specific implementation method is as follows:

[0059] Example 1

[0060] This embodiment takes graphite and TiZrHfTa high-entropy alloy as examples to further illustrate the method of connecting carbon materials using a novel high-entropy alloy solder, including the following steps:

[0061] 1) Remove surface impurities from pure Ti, Zr, Hf, and Ta metals by sanding. Then, weigh each of the four pure metals in an equimolar ratio to obtain a metal mixture with a total mass of approximately 0.6 g. Place the four mixed pure metals in a water-cooled copper crucible under argon protection and heat the metal mixture to melt using an electric arc. After cooling, flip the solidified metal ingot and reheat it to melt. Repeat this process 5 to 6 times to ensure the compositional uniformity of the prepared high-entropy alloy. The cooled alloy ingot is manually rolled into a circular sheet with a thickness of approximately 300 μm and a diameter of approximately 20 mm. The disc is then ground and polished, ultrasonically cleaned in acetone for 10 min, and dried to obtain a high-entropy alloy brazing foil with a thickness of 150–200 μm (the thickness of the foil is maintained within this range due to errors in each grinding and polishing operation, with slight differences in thickness at different locations). Figure 1 The image shows the scanning electron microscope (SEM) microstructure, EDS analysis results, and XRD pattern of the TiZrHfTa high-entropy alloy prepared according to the above method. As shown in the figure, the prepared TiZrHfTa high-entropy alloy has a uniform elemental distribution, with no microsegregation observed, and the elemental ratio is close to the equiatomic ratio. The XRD pattern shows that its microstructure is a single BCC phase.

[0062] 2) The graphite was processed into two circular pieces with a diameter of 20 mm and a thickness of 3 mm by wire electrical discharge machining. The surfaces of the two graphite pieces to be welded were polished smooth by 2000# and 4000# SiC sandpaper, respectively. They were then ultrasonically cleaned in acetone for 10 minutes and then removed and dried.

[0063] 3) Place the TiZrHfTa high-entropy alloy foil between the two graphite discs to be welded to form a "sandwich" structure welding assembly. Place the assembly into a spark plasma sintering (SPS) furnace. The pressure head in the SPS furnace is a graphite pressure head with a diameter of 20 mm, which is combined with the sample to be welded to form a good electrical and thermal conductor.

[0064] 4) Apply a pressure of 5 kN (16 MPa) between the upper and lower pressure heads to ensure good contact and conductivity between the samples to be welded; maintain a vacuum inside the SPS furnace (pressure less than 1×10). -3 Pa);

[0065] 5) Using SPS rapid heating, the SPS furnace was operated at full power, and the sample to be welded was heated for 16 seconds, reaching 2210℃ within this time, with a heating rate exceeding 100℃ / s. This extremely rapid heating caused TiZrHfTa to melt and react violently with the graphite matrix. After the heating process, the sample was cooled with the furnace, reaching below 50℃ within 3 minutes, with a cooling rate exceeding 500℃ / min. After the connection was completed, the sample was removed. The heating curve of the entire SPS rapid connection process is shown below. Figure 2 As shown.

[0066] Figure 3 This is a backscattered electron image of the graphite joint interface obtained in Example 1 under a scanning electron microscope. Figure 4 The figures show the EDS analysis results and XRD patterns of the joint microstructure. As can be seen from the figures, the graphite joint is well-bonded, without cracks, pores, or other defects. The joint microstructure consists of an unreacted residual BCC phase high-entropy alloy layer and FCC phase high-entropy carbide products generated by the carbide reaction, without the formation of intermetallic compounds. EDS analysis results indicate that the high-entropy carbides generated by the reaction have high Zr and Hf contents, while the unreacted high-entropy alloy layer has high Ti and Ta contents. This is due to the different carbide formation energies of different elements. The shear strength of this joint at room temperature is 19.47 MPa, comparable to the interlaminar strength of graphite.

[0067] Example 2

[0068] The difference between this embodiment and Embodiment 1 is that the high-entropy alloy prepared in step 1) is an equimolar ratio of ZrHfNbTa; the base material in step 2) is a C / C composite disc with a diameter of 20 mm and a thickness of approximately 3 mm; and in step 5), a slow SPS heating method is used. First, the sample is heated to 1400°C at a heating rate of 50°C / min, then to 2000°C at a rate of 20°C / min. Due to the slow heating rate, the high-entropy alloy is completely carbonized before reaching its melting point, therefore ZrHfNbTa does not melt. Subsequently, the sample is held at 2000°C for 30 min to allow sufficient diffusion between the high-entropy alloy and the carbon base material. Finally, the sample is cooled to room temperature at a rate of 100°C / min and then removed. Figure 5 The images show the backscattered electron microscopy (SEM) image and EDS elemental analysis results of the C / C composite joint interface obtained in Example 2. As can be seen from the images, the C / C composite joint exhibits good bonding, free from defects such as cracks and pores. The joint microstructure consists of uniform (ZrHfNbTa)C high-entropy carbides formed after complete carburization of the ZrHfNbTa high-entropy alloy. The C / C composite joint obtained in this example exhibits the highest shear strength of 27.3 MPa at 1600℃.

[0069] Example 3

[0070] The difference between this embodiment and Embodiment 1 is that the high-entropy alloy prepared in step 1) is an equimolar ratio of ZrHfNbTa; and in step 5), the SPS rapid heating method is used to apply a heating time of 14s to the sample to be welded, during which the sample to be welded is heated to 2005℃. Figure 6 The images show the backscattered electron microscopy (SEM) image and EDS elemental analysis results of the graphite joint interface obtained in Example 3. As can be seen from the images, the graphite joint is well-bonded, without cracks, pores, or other defects. The extremely rapid heating method causes ZrHfNbTa to melt and react violently with the graphite matrix. The joint microstructure consists of (ZrHfNbTa)C high-entropy carbides formed after the complete carbonization of the ZrHfNbTa high-entropy alloy.

[0071] Example 4

[0072] The difference between this embodiment and embodiment 2 is that the base material used in step 2) is a graphite disc with a diameter of 20 mm and a thickness of 3 mm; and step 5) uses SPS slow heating method, with the final heating temperature of the sample being 2200℃ and held at 2200℃ for 30 min. Figure 7 The images show the backscattered electron microscopy (SEM) image and EDS elemental analysis results of the graphite joint interface obtained in Example 4. As can be seen from the images, the graphite joint microstructure consists of uniform (ZrHfNbTa)C high-entropy carbides formed after complete carbonization of the ZrHfNbTa high-entropy alloy. The graphite joint obtained in this example exhibits a shear strength of 16.3 MPa at room temperature.

[0073] Example 5

[0074] The difference between this embodiment and implementation 4 is that step 5) uses SPS slow heating, and the final heating temperature of the sample is 2000℃, and it is kept at 2000℃ for 60 minutes. Figure 8 The images show the backscattered electron microscopy (SEM) image and EDS elemental analysis results of the graphite joint interface obtained in Example 5. As can be seen from the images, the graphite joint microstructure consists of uniform (ZrHfNbTa)C high-entropy carbides formed after complete carbonization of the ZrHfNbTa high-entropy alloy. The graphite joint obtained in this example exhibits a shear strength of 15.6 MPa at room temperature.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A method for joining carbon materials using high-entropy alloy brazing filler metal, characterized in that: The high-entropy alloy solder has the composition TiZrHfTa, and the molar percentage of each component ranges from 15% to 35%. Specifically, the following steps are included: 1) Preparation of high-entropy alloy brazing foil Weigh the required pure metal according to the high-entropy alloy ratio, and prepare a high-entropy alloy brazing foil with a thickness of 150-200 μm; 2) Connecting carbon materials 2.1) The high-entropy alloy brazing foil obtained in step 1) is placed between the welding surfaces of two pretreated carbon material blocks to be welded, forming a "sandwich" structured welding assembly; 2.2) Place the welded assembly obtained in step 2.1) in a spark plasma sintering furnace and apply pressure to the welded assembly to ensure full contact between the surfaces to be welded; 2.3) Heat treatment of the samples to be welded can be performed in two ways: The first type: The spark plasma sintering furnace operates at full power and heats for 14 to 18 seconds. Within this heating time range, the temperature is heated to 2000℃ to 2300℃. After heating, the furnace is cooled along with the furnace and cooled to below 50℃ within 3 minutes. The cooling rate is greater than 500℃ / min, and the connection is completed. The second type: First, heat the sample to be welded to 1200~1400℃ at a heating rate of 20~60℃ / min, then heat the sample to 1800℃~2200℃ at a rate of 20~40℃ / min, hold at the target temperature for 10~60 min, and then cool to room temperature at a rate of 50~100℃ / min to complete the connection. The obtained sample can be used in ultra-high temperature service environments above 1600℃, and has a maximum shear strength of 27.3 MPa at 1600℃.

2. The method according to claim 1, characterized in that, Step 1) Specifically: 1.1) Weigh the required pure metal according to the high-entropy alloy ratio; 1.2) After the weighed pure metals are mixed, they are melted multiple times by electric arc melting or electromagnetic melting under vacuum or inert atmosphere to obtain high-entropy alloy ingots. 1.3) After the high-entropy alloy ingot has cooled to room temperature, it is taken out and rolled into a foil with a thickness of 300~500μm; 1.4) After grinding, polishing and ultrasonic cleaning of the foil in sequence, a high-entropy alloy brazing foil with a thickness of 150-200 μm is obtained.

3. The method according to claim 2, characterized in that: In step 2.1), the pretreatment refers to grinding, polishing and ultrasonic cleaning the surface of the carbon material block to be welded in sequence; In step 2.2), a pressure of 10–20 MPa is applied to the welded assembly; in the spark plasma sintering furnace, the pressure is less than 1 × 10 MPa. -3 Pa in a vacuum or inert atmosphere.

4. The method according to claim 3, characterized in that: In step 2.3), in the first method, the heating rate is greater than 100℃ / s.

5. The method according to claim 4, characterized in that: The carbon material is a single-phase carbon or a carbon-based composite material.

6. A carbon material connector, characterized in that: The microstructure of the joint reaction layer prepared by any one of claims 1-5 is a single high-entropy carbide ceramic or a microstructure of high-entropy carbide and high-entropy alloy layers.

7. The carbon material connector according to claim 6, characterized in that: It can be used in ultra-high temperature service environments above 1600℃.

8. The carbon material connector according to claim 7, characterized in that: It has a maximum shear strength of 27.3 MPa at 1600℃.

Images