A brazing method for improving interfacial reaction of a composite filler metal by self-adapting high-entropy ceramics

Abstract

The application discloses a brazing method for improving interface reaction of composite filler metal self-adapting high-entropy ceramics, which comprises the following steps: firstly, uniformly mixing filler metal powder and high-entropy ceramic powder, adding anhydrous ethanol and grinding balls, ball milling to a slurry state, and obtaining a composite slurry; drying the composite slurry to obtain a composite filler metal, wherein the high-entropy ceramic particles in the composite filler metal account for 2-6 wt% of the total mass of the composite filler metal; then, mixing the composite filler metal with an adhesive and coating the mixture on a to-be-welded surface of a high-entropy ceramic block, and forming a to-be-brazed structure after adhesion; finally, heating the to-be-brazed structure to a brazing temperature according to a process curve, melting the composite filler metal to form a liquid phase, preferentially causing in-situ reaction of the first active element in the composite filler metal and the high-entropy ceramic particles, consuming part of the first active element, and enriching the remaining first active element and / or the second active element in the liquid filler metal on the surface of the high-entropy ceramic block and inducing interface reaction, and obtaining a high-entropy ceramic brazed joint after holding at the brazing temperature for a period of time and cooling. The method avoids the problem that high activity of the first active element in the commercial filler metal causes severe dissolution of the high-entropy ceramic matrix, and the joint strength is increased by more than 24%.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy ceramic brazing technology, and in particular relates to a brazing method for improving interfacial reaction of composite brazing filler metal adaptively to high-entropy ceramics. Background Technology

[0002] Entropy represents the degree of disorder in a system. A mixture entropy greater than 1.5R (where R is the gas constant) is generally considered high entropy. The concept of high entropy was first used to develop high-entropy alloy materials. In recent years, high-entropy ceramic structural materials have been developed and are expected to meet the material requirements of various extreme service environments and complex service conditions in fields such as aerospace vehicles and the nuclear industry. High-entropy ceramics are composed of four or more equimolar or near-equimolar transition metal elements and one or two non-metallic elements. The multi-component composition gives high-entropy ceramics thermodynamic high-entropy effects, structural lattice distortion, kinetic hysteresis diffusion effects, and performance cocktail effects.

[0003] High-entropy ceramics are currently prepared using methods such as hot pressing sintering, plasma sintering, or microwave sintering. To further advance the application of high-entropy ceramics in components, the large-size and complex structural forming of these bulk ceramics inevitably involves brazing technology. To match the high-temperature application environment of high-entropy ceramics, high-temperature active brazing filler metals are often used in the brazing process, such as TiNi alloy brazing filler metals, BNi2 brazing filler metals, TiZrNiCu alloy brazing filler metals, or high-entropy alloy brazing filler metals based on the FeCoCrNi system. The adsorption of active elements (such as Ti, Zr, and Hf) on the surface of the high-entropy ceramic and the interfacial reactions they induce are key to achieving high-quality metallurgical bonding between the liquid brazing filler metal and the high-entropy ceramic. However, the intrinsic properties of multi-component ceramics and the high-entropy effect make high-entropy ceramics exhibit unique characteristics at the brazing interface that differ from traditional ceramics. Specifically, at high brazing temperatures, the active elements in the liquid brazing alloy continuously react with the high-entropy ceramic matrix, causing the high-entropy ceramic to dissolve violently into the liquid brazing alloy and form a continuous and complex compound layer at the interface. This results in poor stability of the interface structure of the high-entropy ceramic brazed joint, posing unpredictable risks to the reliability of the high-entropy ceramic brazed joint.

[0004] To prepare high-entropy ceramic brazed joints with stable interfacial structure, high strength, and reliability, optimizing the interfacial reaction is crucial, with the core being controlling the types and contents of active elements participating in the interfacial reaction. According to existing reports on high-entropy ceramic brazing technology, researchers generally improve joint strength by optimizing the filler metal composition. However, active elements originate not only from the filler metal alloy itself but also from the dissolution and diffusion of the high-entropy ceramic matrix at the interface. This limits the effectiveness of improving the interfacial reaction by optimizing the types and contents of active elements in the filler metal. Furthermore, considering the flexibility of high-entropy ceramic composition, filler metal designs for single high-entropy ceramic systems are difficult to apply to brazing other high-entropy ceramic systems. Therefore, it is necessary to study adaptive methods for filler metals to high-entropy ceramics to more easily control the brazing interfacial reaction of high-entropy ceramics and improve the strength of high-entropy ceramic joints. Summary of the Invention

[0005] To address the shortcomings of existing high-entropy ceramic brazing technology, this invention aims to solve the problems of excessive dissolution of the ceramic matrix caused by the violent reaction of active elements at the solid-liquid interface between traditional brazing filler metal and high-entropy ceramic, the complex interface reaction products resulting from the synergistic participation of multiple active elements, and the insufficient stability of the interface structure. The invention provides a brazing method that uses a composite brazing filler metal to adapt to high-entropy ceramics and improve the interface reaction.

[0006] The technical solution adopted by the present invention to solve the aforementioned technical problem is as follows:

[0007] A brazing method for improving interfacial reaction in high-entropy ceramics using composite brazing filler metal, characterized by comprising the following steps:

[0008] Step 1: Mix the brazing filler metal powder and high-entropy ceramic powder evenly to obtain a composite powder; add anhydrous ethanol and grinding balls to the composite powder and ball mill it into a slurry state to obtain a composite slurry; dry the composite slurry to obtain a composite brazing filler metal, in which the high-entropy ceramic particles account for 2-6 wt% of the total mass of the composite brazing filler metal.

[0009] Step 2: Grind the surfaces of the two high-entropy ceramic blocks to be welded smooth, ultrasonically clean them in acetone, and then dry them;

[0010] Step 3: Thoroughly mix the composite brazing filler metal and brazing adhesive into a paste. Apply the paste evenly to the surface of the high-entropy ceramic block to be brazed, so that the composite brazing filler metal completely fills and adheres between the two high-entropy ceramic blocks to form the structure to be brazed.

[0011] Step 4: Place the structure to be brazed in a high-temperature vacuum furnace. When the vacuum level inside the furnace drops to 2.0 × 10⁻⁶, -3When the temperature is below Pa, the high-temperature vacuum furnace is heated to 400℃ at a rate of 10℃ / min and held for a period of time; then heated to 200-250℃ below the brazing temperature at a rate of 10℃ / min and held for a period of time; then heated to the brazing temperature at a rate of 10℃ / min, the composite brazing filler melts to form a liquid phase, in which high-entropy ceramic particles are uniformly distributed. The first active element in the composite brazing filler preferentially reacts with the high-entropy ceramic particles in situ, and some of the first active element is consumed. The remaining first active element and / or the second active element in the liquid brazing filler enrich on the surface of the high-entropy ceramic block and induce an interfacial reaction. The temperature is held at the brazing temperature for 10-20 min to allow the high-entropy ceramic block and composite brazing filler to react fully at the interface; after the holding period, the high-temperature vacuum furnace is cooled to 400℃ at a rate of 5℃ / min, the liquid brazing filler solidifies and reliably connects with the high-entropy ceramic block to obtain a high-entropy ceramic brazed joint. Finally, the high-entropy ceramic brazed joint is allowed to cool naturally to room temperature with the furnace.

[0012] Furthermore, the first active element in the composite brazing filler metal refers to the element with the highest activity at the brazing temperature, which is the main controlling element that preferentially accumulates on the surface of the high-entropy ceramic block and induces interfacial reactions to generate the first interfacial reaction product.

[0013] Furthermore, the second active element in the composite brazing filler metal refers to the key controlling element that induces the composite brazing filler metal to further react with the first interface reaction product after the content of the first active element in the composite brazing filler metal decreases during the brazing process.

[0014] Furthermore, the high-entropy ceramic powder is homogeneous with the high-entropy ceramic to be welded and consists of submicron-sized particles.

[0015] Furthermore, the solder powder is a commercially available high-temperature active solder, including but not limited to titanium-based solder, nickel-based solder, or silver-based solder.

[0016] Furthermore, the holding time for the high-temperature vacuum furnace at 400℃ and 800℃ is 20-40 minutes.

[0017] Furthermore, the mass ratio of anhydrous ethanol to grinding balls added to the composite powder is 1:10 to 1:5.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention does not require changing the chemical composition of traditional commercial active solders. By introducing high-entropy ceramic particles that are homogeneous with the high-entropy ceramic to be soldered into the solder, the active element content in the solder is adapted to the high-entropy ceramic matrix, optimizing the activity of the main controlling element of the interface reaction between the liquid solder and the high-entropy ceramic, thereby controlling the interface reaction products in situ.

[0020] 2. In the composite brazing filler metal of the present invention, the first active element preferentially reacts with the high-entropy ceramic particles in situ. The remaining first active element and / or the second active element (if any) in the composite brazing filler metal are enriched at the interface between the high-entropy ceramic matrix and the liquid brazing filler metal and induce an interfacial reaction. The interfacial reaction products are uniformly distributed at the interface, which effectively avoids the problem that when commercial brazing filler metal is used to braze high-entropy ceramics directly, the high activity of the first active element in the liquid brazing filler metal causes the high-entropy ceramic matrix to dissolve violently and form a continuous reaction layer at high brazing temperatures. The joint strength can be improved by more than 24%.

[0021] 3. The composite brazing alloy preparation method in this method is simple and applicable to the interfacial reaction control of high-entropy ceramics of various component types during brazing. It is also applicable to the in-situ optimization of the active element content in various commercial brazing alloys, overcoming the limitations of designing special brazing alloys for high-entropy ceramic brazing by optimizing the type and content of active elements. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of the composite solder from Example 1;

[0023] Figure 2 This is a scanning electron microscope image of the interface of the high-entropy ceramic brazed joint prepared in Example 1;

[0024] Figure 3 This is a scanning electron microscope image of the fracture surface of the high-entropy ceramic brazed joint prepared in Example 1;

[0025] Figure 4 This is a scanning electron microscope image of the interface of the high-entropy ceramic brazed joint prepared in Example 2;

[0026] Figure 5 This is a scanning electron microscope image of the interface of the high-entropy ceramic brazed joint prepared in Example 3;

[0027] Figure 6 The image shows a scanning electron microscope (SEM) image of the interface of the high-entropy ceramic brazed joint prepared in Comparative Example 1.

[0028] Figure 7 The image shows a scanning electron microscope (SEM) image of the fracture surface of the high-entropy ceramic brazed joint prepared in Comparative Example 1. Detailed Implementation

[0029] Specific embodiments are given below with reference to the accompanying drawings. These specific embodiments are only used to further illustrate the technical solutions of the present invention, but are not intended to limit the scope of protection of this application.

[0030] This invention relates to a brazing method (hereinafter referred to as the method) that uses composite brazing filler metal to adaptively improve interfacial reactions in high-entropy ceramics, specifically comprising the following steps:

[0031] Step 1: Uniformly mix the brazing filler metal powder and high-entropy ceramic powder to obtain a composite powder; add anhydrous ethanol and zirconia grinding balls to the composite powder, with a ball-to-powder mass ratio of 1:10 to 1:5, and ball mill in an agate jar for 2 to 5 hours until a slurry is formed, with a ball milling speed of 200 to 300 rpm, to obtain a composite slurry; dry the composite slurry in a drying oven to obtain the composite brazing filler metal; the high-entropy ceramic particles in the composite brazing filler metal account for 2 to 6 wt% of the total mass of the composite brazing filler metal;

[0032] Step 2: Grind the surfaces of the two high-entropy ceramic blocks to be welded until smooth. Place the ground high-entropy ceramic blocks in acetone medium for ultrasonic cleaning for 15-30 minutes, and then dry the high-entropy ceramic blocks.

[0033] Step 3: Mix the composite brazing filler metal with an appropriate amount of brazing adhesive (a mixture of octyl acetate and cellulose nitrate) to form a paste. Apply the paste evenly to the surface of the high-entropy ceramic block to be brazed, so that the composite brazing filler metal completely fills and adheres between the two high-entropy ceramic blocks to form the structure to be brazed.

[0034] Step 4: Place the structure to be brazed in a high-temperature vacuum furnace. When the vacuum level inside the furnace drops to 2.0 × 10⁻⁶, -3 When the temperature is below Pa, the high-temperature vacuum furnace is heated to 400℃ at a heating rate of 10℃ / min and held for 20-40 min to make the temperature inside the furnace uniform. The high-temperature vacuum furnace is then heated to 200-250℃ below the brazing temperature at a heating rate of 10℃ / min and held for 20-40 min to further make the temperature inside the furnace uniform. The high-temperature vacuum furnace is then heated to the brazing temperature given by the brazing filler metal at a heating rate of 10℃ / min. The composite brazing filler metal melts and first forms a liquid phase. Solid high-entropy ceramic particles are uniformly distributed in the liquid brazing filler metal. The high-entropy ceramic particles have a high specific surface area and surface defects introduced during the ball milling process. The first active element in the composite brazing filler metal preferentially reacts with the high-entropy ceramic particles in situ. Some of the first active element is consumed as the in situ reaction proceeds. The remaining first active element and / or the second active element in the composite brazing filler metal (if any) are enriched on the surface of the high-entropy ceramic block and induce an interfacial reaction. The temperature is held at the brazing temperature for 10-20 min to allow the high-entropy ceramic block and the composite brazing filler metal to react fully at the interface.

[0035] After the heat preservation is completed, the temperature of the high-temperature vacuum furnace is reduced to 400℃ at a cooling rate of 5℃ / min. The liquid brazing filler metal solidifies and reliably connects with the high-entropy ceramic block to obtain a high-entropy ceramic brazed joint. The joint is then naturally cooled to room temperature with the furnace.

[0036] The high-entropy ceramic powder is a submicron particle obtained by high-temperature sintering, mechanical alloying, and pulse discharge-induced bulk crushing. The high-entropy ceramic powder is homogeneous with the high-entropy ceramic to be welded, that is, the chemical elements and composition ratios are consistent.

[0037] The first active element in the composite brazing filler metal refers to the element with the highest activity at the brazing temperature. It is the main controlling element that preferentially accumulates on the surface of the high-entropy ceramic block and induces interfacial reactions to generate the first interfacial reaction product.

[0038] The second active element in the composite brazing filler metal refers to the key element that, during the brazing process, induces the composite brazing filler metal to further react with the first interface reaction products after the content of the first active element in the composite brazing filler metal decreases.

[0039] The consumption of the first active element in the composite solder is positively correlated with the mass fraction of high-entropy ceramic particles in the composite solder. The first active element is consumed in the in-situ reaction between the liquid solder and the high-entropy ceramic particles, which reduces the concentration of the first active element at the interface between the liquid solder and the high-entropy ceramic block. The content and even the type of the first active element participating in the interface reaction can be controlled by changing the mass fraction of the high-entropy ceramic particles.

[0040] The interface structure of the high-entropy ceramic brazed joint may contain a small number of incompletely reacted high-entropy ceramic particles. These high-entropy ceramic particles are discretely distributed in the brazing filler metal structure and can strengthen the brazing filler metal as a hard phase.

[0041] The solder powder is a commercially available high-temperature active solder powder, including but not limited to TiZrNiCu solder, nickel-based solders such as BNi2, and silver-based solders such as AgCuTi.

[0042] The density of the high-entropy ceramic block is above 95%. The high-entropy ceramic contains equimolar or near-equimolar amounts of four or six transition metal elements (hafnium, zirconium, titanium, tantalum, niobium, vanadium, molybdenum, tungsten, chromium) and one or two non-metallic elements (carbon, boron, nitrogen), such as (WMoVNbTa)C, (HfZrTiTaNb)C and other high-entropy ceramics.

[0043] Example 1

[0044] This embodiment uses (WMoVNbTa)C high-entropy ceramic and TiZrNiCu solder as an example to illustrate a brazing method in which the composite solder adapts to the high-entropy ceramic to improve the interfacial reaction, including the following steps:

[0045] Step 1: Commercially available TiZrNiCu solder powder and (WMoVNbTa)C high-entropy ceramic powder are uniformly mixed to obtain a composite powder. Anhydrous ethanol and zirconium oxide grinding balls are added to the composite powder at a ball-to-powder ratio of 1:10. The mixture is then ball-milled in an agate jar for 3 hours to a slurry state at a milling speed of 200 rpm to obtain a composite slurry. The composite slurry is then dried in a drying oven to obtain the composite solder. The (WMoVNbTa)C high-entropy ceramic particles in the composite solder account for 4 wt% of the total mass of the composite solder.

[0046] Step 2: Grind the surfaces of the two (WMoVNbTa)C high-entropy ceramic blocks to be welded until smooth using a #2000 diamond grinding wheel. The dimensions of the two high-entropy ceramic blocks are 10×10×5mm. 3 and 5×5×5mm 3 The connection area of ​​the surfaces to be welded is 5×5mm. 2 The polished (WMoVNbTa)C high-entropy ceramic block was placed in acetone medium and ultrasonically cleaned for 20 minutes, and then the (WMoVNbTa)C high-entropy ceramic block was dried.

[0047] Step 3: Mix the composite brazing filler metal with an appropriate amount of brazing adhesive (a mixture of octyl acetate and cellulose nitrate) to form a paste. Apply the paste evenly to the surface of the (WMoVNbTa)C high-entropy ceramic block to be brazed, so that the composite brazing filler metal fills the space between the two (WMoVNbTa)C high-entropy ceramic blocks and adheres them to form the structure to be brazed.

[0048] Step 4: Place the structure to be brazed in a high-temperature vacuum furnace. When the vacuum level inside the furnace drops to 2.0 × 10⁻⁶, -3 When the temperature is below Pa, the high-temperature vacuum furnace is heated to 400℃ at a heating rate of 10℃ / min and held for 30min. Then, the furnace is heated to 800℃ at a heating rate of 10℃ / min and held for 30min to ensure uniform temperature within the furnace. The temperature is then further increased to a brazing temperature of 980℃ at a heating rate of 10℃ / min. When the temperature reaches the melting point of the composite brazing filler metal, it melts to form a liquid brazing filler metal. Solid (WMoVNbTa)C high-entropy ceramic particles are uniformly distributed within the liquid filler metal. The first active element Zr in the composite solder preferentially reacts in situ with the (WMoVNbTa)C high-entropy ceramic particles. Most of the first active element Zr is consumed as the reaction proceeds. The remaining first active element Zr and the second active element Ti in the composite solder are enriched on the surface of the (WMoVNbTa)C high-entropy ceramic block and induce an interfacial reaction. The soldering temperature is 980℃ for 10 min to allow the two (WMoVNbTa)C high-entropy ceramic blocks and the composite solder to react fully at the interface.

[0049] After the heat preservation is completed, the temperature of the high-temperature vacuum furnace is reduced to 400℃ at a cooling rate of 5℃ / min. The liquid brazing filler metal solidifies and reliably connects with the (WMoVNbTa)C high-entropy ceramic to obtain the (WMoVNbTa)C high-entropy ceramic brazed joint. Finally, the joint is allowed to cool naturally to room temperature with the furnace.

[0050] Figure 1This is a scanning electron microscope image of the composite brazing filler metal; the micron-sized spherical particles and irregular blocks are the ball-milled brazing filler metal powder, and the particles with a size of less than 1 μm that are attached to and scattered on the surface of the brazing filler metal powder are high-entropy ceramic powder. The high-entropy ceramic powder and the brazing filler metal powder are mixed evenly.

[0051] Figure 2 The image shows a scanning electron microscope (SEM) image of the interface of a (WMoVNbTa)C high-entropy ceramic brazed joint. The image reveals no cracks or other defects at the interface. The first active element, Zr, in the composite brazing filler metal preferentially reacts with the (WMoVNbTa)C high-entropy ceramic particles, causing the (WMoVNbTa)C high-entropy ceramic particles to disappear and some Zr atoms to be consumed. The remaining Zr atoms alter the chemical composition of the (WMoVNbTa)C high-entropy ceramic at the interface, transforming it into a non-stoichiometric (WMoVNbTa)C high-entropy ceramic. The second active element, Ti, in the composite brazing filler metal enriches on the surface of the non-stoichiometric (WMoVNbTa)C high-entropy ceramic bulk and induces an interfacial reaction, forming a black and white mixed layer of reaction products. This mixed layer consists of fine (Ti,Nb,Ta,Zr)C carbides and TiAl-type high-entropy metal compounds. Flocculent (Zr,Ti,Nb)C carbide structures are also observed on the outer side of the mixed layer of reaction products. The shear strength of the (WMoVNbTa)C high-entropy ceramic brazed joint is 240 MPa, which is 23.7% higher than that of the TiZrNiCu brazing filler metal. Figure 3 The image shows a scanning electron microscope (SEM) image of the shear fracture surface of a (WMoVNbTa)C high-entropy ceramic brazed joint. High-entropy ceramic was observed on the entire fracture surface, indicating that the fracture occurred in the high-entropy ceramic matrix. This confirms the reliable metallurgical connection at the brazed joint interface.

[0052] Example 2

[0053] The difference between this embodiment and Embodiment 1 is that, in step 1, the (WMoVNbTa)C high-entropy ceramic particles in the composite solder account for 2wt% of the total mass of the composite solder.

[0054] The scanning electron microscope (SEM) image of the (WMoVNbTa)C high-entropy ceramic brazed joint interface obtained in this embodiment is shown below. Figure 4 As shown, the interface is free of defects such as cracks. The thickness of the reaction product mixture layer at the interface increases, leading to increased dissolution of the (WMoVNbTa)C high-entropy ceramic matrix. This is because the lower content of (WMoVNbTa)C high-entropy ceramic particles in the composite brazing filler metal preferentially reacts in situ with the first active element, Zr, resulting in an increase in the remaining Zr and a weakened inhibitory effect on the interfacial reaction. Overall, the microstructure of the (WMoVNbTa)C high-entropy ceramic brazed joint is similar to that of Example 1, and the shear strength of the joint is 217 MPa.

[0055] Example 3

[0056] The difference between this embodiment and Embodiment 1 is that, in step 1, the (WMoVNbTa)C high-entropy ceramic particles of the composite solder account for 6 wt% of the total mass of the composite solder.

[0057] The scanning electron microscope (SEM) image of the (WMoVNbTa)C high-entropy ceramic brazed joint interface obtained in this embodiment is shown below. Figure 5 As shown, there are no defects such as cracks at the interface. Due to the large consumption of the first active element Zr in the composite brazing filler metal, the reaction product mixture layer at the interface basically disappears, and the shear strength of the joint is 201 MPa.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that step 1, which prepares the composite solder, is not required. In step 3, the TiZrNiCu solder is fully mixed with an appropriate amount of soldering adhesive to form a paste. The paste is then uniformly coated onto the surface of the (WMoVNbTa)C high-entropy ceramic block to be soldered, so that the TiZrNiCu solder completely fills and adheres between the two high-entropy ceramic blocks to form the structure to be soldered.

[0060] The scanning electron microscope (SEM) image of the interface of the (WMoVNbTa)C high-entropy ceramic brazed joint obtained in this comparative example is shown below. Figure 6 As shown, the interface is free of cracks and other defects. The active element Zr in the TiZrNiCu solder induces a transformation in the (WMoVNbTa)C high-entropy ceramic matrix. The (WMoVNbTa)C high-entropy ceramic matrix undergoes intense selective dissolution at the interface, generating a large amount of reaction product mixed layer and a continuous (Zr,Ti,Nb)C layer on the interface. The shear strength of the joint is 194 MPa. The scanning electron microscope image of the shear fracture surface of the joint is shown below. Figure 7 As shown, the (Ti,Nb,Ta,Zr)C phase was observed on the fracture surface, which confirms that the intense dissolution of high-entropy ceramics at the interface and the formation of a mixed layer of reaction products can easily lead to joint failure.

[0061] Any aspects not described in this invention are applicable to the prior art.

Claims

1. A brazing method for improving interfacial reaction in composite brazing filler metals adapted to high-entropy ceramics, characterized in that, The method includes the following steps: Step 1: Uniformly mix the brazing filler metal powder and the high-entropy ceramic powder homogeneous with the high-entropy ceramic to be soldered to obtain a composite powder; add anhydrous ethanol and grinding balls to the composite powder and ball mill to a slurry state to obtain a composite slurry; dry the composite slurry to obtain a composite brazing filler metal, wherein the high-entropy ceramic particles in the composite brazing filler metal account for 2-6 wt% of the total mass of the composite brazing filler metal. Step 2: Grind the surfaces of the two high-entropy ceramic blocks to be welded smooth, ultrasonically clean them in acetone, and then dry them; Step 3: Thoroughly mix the composite brazing filler metal and brazing adhesive into a paste. Apply the paste evenly to the surface of the high-entropy ceramic block to be brazed, so that the composite brazing filler metal completely fills and adheres between the two high-entropy ceramic blocks to form the structure to be brazed. Step 4: Place the structure to be brazed in a high-temperature vacuum furnace. When the vacuum level inside the furnace drops to 2.0 × 10⁻⁶, -3 When the temperature is below Pa, the high-temperature vacuum furnace is heated to 400 ℃ at a rate of 10 ℃ / min and held for a period of time; then, it is heated to 200~250 ℃ below the brazing temperature at a rate of 10 ℃ / min and held for a period of time; then, it is heated to the brazing temperature at a rate of 10 ℃ / min, and the composite brazing filler melts to form a liquid phase. High-entropy ceramic particles are uniformly distributed in the liquid brazing filler. The first active element in the composite brazing filler preferentially reacts with the high-entropy ceramic particles in situ, and some of the first active element is consumed. The remaining first active element and / or the second active element in the liquid brazing filler enrich on the surface of the high-entropy ceramic block and induce an interfacial reaction. The temperature is held at the brazing temperature for 10~20 min to allow the high-entropy ceramic block and the composite brazing filler to react fully at the interface; after the holding period, the high-temperature vacuum furnace is cooled to 400 ℃ at a rate of 5 ℃ / min, and the liquid brazing filler solidifies and reliably connects with the high-entropy ceramic block to obtain a high-entropy ceramic brazed joint. Finally, the high-entropy ceramic brazed joint is allowed to cool naturally to room temperature with the furnace. The first active element in the composite brazing filler metal refers to the element with the highest activity at the brazing temperature. It is the main controlling element that preferentially accumulates on the surface of the high-entropy ceramic block and induces interfacial reactions to generate the first interfacial reaction product. The second active element in the composite brazing filler metal refers to the key element that, during the brazing process, induces further reaction between the composite brazing filler metal and the first interface reaction product after the content of the first active element in the composite brazing filler metal decreases.

2. The brazing method for improving interfacial reaction of composite brazing filler metal with adaptive high-entropy ceramic according to claim 1, characterized in that, The high-entropy ceramic powder, which is homogeneous with the high-entropy ceramic to be welded, consists of submicron-sized particles.

3. The brazing method for improving interfacial reaction of composite brazing filler metal with adaptive high-entropy ceramic according to claim 1 or 2, characterized in that, The solder powder is a commercially available high-temperature active solder, including but not limited to titanium-based solder, nickel-based solder, or silver-based solder.

4. The brazing method for improving interfacial reaction of composite brazing filler metal with adaptive high-entropy ceramic according to claim 1, characterized in that, The holding time for the high-temperature vacuum furnace at 400 ℃ and 800 ℃ is 20~40 min.

5. The brazing method for improving interfacial reaction of composite brazing filler metal with adaptive high-entropy ceramic according to claim 1, characterized in that, The mass ratio of anhydrous ethanol to grinding balls in the composite powder is 1:10 to 1:5.

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