High-entropy alloy solder applied to connecting silicon carbide ceramic parts and preparation method and application thereof

Abstract

The application discloses a high-entropy alloy solder applied to connecting silicon carbide ceramic pieces and a preparation method and application thereof, and belongs to the field of silicon carbide ceramic connection. The high-entropy alloy solder is composed of metal single-substance powders of Fe, Co, Cr, Ni and Mo, and the atomic percentages of the metal single-substance powders are the same. Alternatively, the high-entropy alloy solder is composed of metal single-substance powders of Fe, Co, Cr, Ni, Mo and Ti, and the atomic percentages of the metal single-substance powders are the same. The method for connecting silicon carbide ceramic pieces by using the high-entropy alloy solder comprises the following steps: mechanically mixing metal single substances of high-entropy alloy elements, and then generating a high-entropy alloy connecting layer through in-situ reaction to be completed. The method not only has simple process and low cost, but also is convenient for adjusting the components of the high-entropy alloy solder, and can obtain a silicon carbide connecting piece with a four-point bending strength of 315 MPa.

Description

Technical Field

[0001] This invention relates to a high-entropy alloy solder for connecting silicon carbide ceramic parts, its preparation method and application, belonging to the field of silicon carbide ceramic bonding. Background Technology

[0002] Silicon carbide ceramics and their composites are widely used in aerospace, electronics, and chemical industries due to their advantages such as good high-temperature strength, high thermal conductivity, low density, and low coefficient of thermal expansion. In practical engineering applications, such as space mirrors, heat exchange tubes, and engine turbine blades, silicon carbide ceramics and their composites require large dimensions and specific complex shapes. However, the poor plasticity, low toughness, and poor impact resistance of silicon carbide ceramics make them difficult to deform and machine like metal materials. Furthermore, the integral molding of complex-shaped or large-sized devices is difficult and costly. Utilizing joining technologies to assemble simple, small-sized components into complex, larger components is an important means of realizing these applications.

[0003] Commonly used joining techniques include direct diffusion joining, brazing joining, reactive joining, precursor joining, and glass joining. Among these, brazing joining has advantages such as simple process, low joining temperature, and good joint reliability, and is widely used in joining silicon carbide ceramics. Currently, the solders used for brazing silicon carbide ceramics are mainly silver, copper, and titanium-based active low-temperature solders, as well as nickel-based and titanium-based high-temperature solders. These solders have a higher coefficient of thermal expansion than silicon carbide ceramics, resulting in greater residual thermal stress at the joint and a tendency to form brittle intermetallic compounds. Therefore, developing a new silicon carbide ceramic solder has become a research hotspot. Summary of the Invention

[0004] To address the challenges of preparing metallic solders, the significant difference in thermal expansion coefficients between the solder and the silicon carbide substrate, and the low operating temperature, this invention provides a high-entropy alloy solder for joining silicon carbide ceramic components, along with its preparation method and applications. The method for joining silicon carbide ceramic components using the high-entropy alloy solder of this invention involves first mechanically mixing the metallic elements of the high-entropy alloy, and then generating a high-entropy alloy bonding layer through an in-situ reaction. This method is not only simple and low-cost, but also allows for easy adjustment of the high-entropy alloy solder composition, resulting in silicon carbide connectors with a four-point bending strength as high as 315 MPa.

[0005] In a first aspect, the present invention provides a high-entropy alloy solder for connecting silicon carbide ceramic components. The high-entropy alloy solder is composed of elemental metal powders of Fe, Co, Cr, Ni, and Mo, with each elemental metal powder having the same atomic percentage.

[0006] Secondly, the present invention provides another high-entropy alloy solder for joining silicon carbide ceramic parts. The high-entropy alloy solder is composed of elemental metal powders of Fe, Co, Cr, Ni, Mo, and Ti, with each element having the same atomic percentage. Cr, Mo, and Ti have low coefficients of thermal expansion and high reactivity, which contributes to obtaining a good silicon carbide joint.

[0007] Preferably, the particle size of the metal element powder is 1-20 μm.

[0008] Thirdly, the present invention provides a method for preparing a high-entropy alloy solder for connecting silicon carbide ceramic parts. Various elemental metal powders are weighed according to equiatomic percentages, and a process control agent is added. After ball milling, the mixture is dried to remove the process control agent, thus obtaining the high-entropy alloy solder.

[0009] Preferably, the process control agent is anhydrous ethanol, and the mass ratio of the process control agent to the metal element powder is 3-10%.

[0010] Fourthly, the present invention provides a method for joining silicon carbide ceramic parts using the aforementioned high-entropy alloy solder. The method includes: mixing the high-entropy alloy solder used for joining silicon carbide ceramic parts with an adhesive and a solvent to form a high-entropy alloy slurry; then uniformly coating the high-entropy alloy slurry onto the surface of the silicon carbide ceramic parts to be joined; and finally butt-joining the silicon carbide ceramic parts coated with the high-entropy alloy slurry, followed by heat treatment to obtain a silicon carbide connector.

[0011] Preferably, the material of the silicon carbide ceramic part is one or more of silicon carbide, carbon fiber reinforced silicon carbide, and silicon carbide fiber reinforced silicon carbide.

[0012] Preferably, the adhesive is at least one of polyvinyl butyral and polyvinyl alcohol, and the solvent is at least one of anhydrous ethanol, terpineol, and deionized water.

[0013] Preferably, the mass ratio of the high-entropy alloy solder, solvent and binder is (40-60):(40-60):(1-5).

[0014] Preferably, the heat treatment connection temperature is 1200-1500℃, the holding time is 30-120min, the pressure is 5-40MPa, and the atmosphere is a vacuum or argon atmosphere; preferably, the temperature is increased to the heat treatment connection temperature at a heating rate of 5-20℃ / min. Attached Figure Description

[0015] Figure 1 The image shows the XRD pattern of the high-entropy alloy solder after vacuum ball milling in Example 1.

[0016] Figure 2The image shows the SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in Example 1.

[0017] Figure 3 The image shows the XRD pattern of the high-entropy alloy solder after vacuum ball milling in Example 4.

[0018] Figure 4 The image shows the SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in Example 4.

[0019] Figure 5 The image shows the SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in Example 5.

[0020] Figure 6 The image shows the SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in Example 6.

[0021] Figure 7 The image shows the SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in Comparative Example 1. Detailed Implementation

[0022] The present invention is further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention. Unless otherwise specified, all percentage contents refer to mass percentages.

[0023] The method for joining silicon carbide ceramic parts using the high-entropy alloy solder described in this invention involves first mechanically mixing the metallic elements of the high-entropy alloy, and then generating a high-entropy alloy bonding layer through an in-situ reaction. Specifically, this invention provides a method for joining silicon carbide ceramic parts using the aforementioned high-entropy alloy solder. This includes: mixing the high-entropy alloy solder with a binder and a solvent to form a high-entropy alloy slurry; then uniformly coating the high-entropy alloy slurry onto the surface of the silicon carbide ceramic parts to be joined; butt-joining two silicon carbide ceramic parts coated with the high-entropy alloy slurry; and finally performing heat treatment to join them, thereby obtaining a silicon carbide connector. The following details each step.

[0024] High-entropy alloy solder (also known as high-entropy alloy mixed powder) is prepared by weighing each elemental metal powder according to equiatomic percentages and adding a process control agent. The powder is then ball-milled in a ball mill jar and dried (to remove the process control agent) to obtain the high-entropy alloy solder.

[0025] In some embodiments, the high-entropy alloy solder is a mixture of powders of corresponding elemental metals Fe, Co, Cr, Ni, and Mo. In other embodiments, the high-entropy alloy solder is a mixture of powders of corresponding elemental metals Fe, Co, Cr, Ni, Mo, and Ti. In the high-entropy alloy solder, each elemental metal has an equiatomic percentage. That is, the atomic percentage of each elemental metal powder in the high-entropy alloy solder is the same, which helps to form a high-entropy alloy solid solution and prevents the formation of brittle intermetallic compounds. In some technical solutions, the bonding layer mainly consists of a silicon-rich high-entropy solid solution phase and some carbides.

[0026] Cr, Mo, and Ti have low coefficients of thermal expansion and high reactivity, which contributes to obtaining good silicon carbide joints. The high-entropy alloy solder provided by this invention contains Cr, Ti, and Mo, which have low coefficients of thermal expansion, helping to reduce the difference in thermal expansion coefficients between the solder and the silicon carbide matrix, thus reducing the generation of thermal stress. In addition, the addition of Mo has a very significant solid solution strengthening effect, which can refine the grains and further improve the strength of the alloy, especially its high-temperature strength; the addition of Ti increases the reactivity of the solder, enhances interfacial bonding, and thus improves the connection strength. The atomic number of Ti is close to that of the other elements, which is conducive to the formation of high-entropy alloy compounds.

[0027] The particle size of the metal elemental powder is 1-20 μm, preferably 1-5 μm. Compared with nanoscale powder, micron-scale elemental powder is simpler to prepare, has lower cost, and does not cause metal powder explosion.

[0028] The process control agent is anhydrous ethanol. Anhydrous ethanol can prevent excessive mechanical alloying of the elemental metal powder, and it is also easy to remove. The process control agent accounts for 3-10% of the mass of the high-entropy alloy solder. As an example, the process control agent accounts for 5% of the mass of the high-entropy alloy solder.

[0029] In the preparation of high-entropy alloy solder, ball milling is carried out under a vacuum or argon atmosphere. This prevents oxidation of the elemental metal powder. The milling jar can be made of stainless steel. The milling media can be stainless steel balls. The ball-to-material ratio can be adjusted as needed. As an example, the ball-to-material ratio (mass of milling media: total mass of metal powder and process control agent) is 2-4:1. The milling speed is 200-600 r / min, and the milling time is 24-72 h. As an example, the milling speed is 500 r / min, and the milling time is 36 h. During the milling process, the mill is stopped for 1 h every 5 h of rotation. The total milling time does not include downtime. Drying is carried out in a vacuum drying oven. The drying temperature is 60-90℃, and the drying time is 24-48 h. As an example, the drying temperature is 80℃, and the drying time is 24 h.

[0030] A high-entropy alloy slurry (also known as a high-entropy alloy suspension) is prepared. The high-entropy alloy suspension comprises high-entropy alloy solder, a binder, and a solvent. The mass ratio of the high-entropy alloy solder, solvent, and binder can be (40-60):(40-60):(1-5). The binder is at least one of polyvinyl butyral and polyvinyl alcohol, preferably polyvinyl butyral. As an example, the amount of binder added can be 2.5% of the sum of the mass of the solvent and the high-entropy alloy solder. The solvent is at least one of anhydrous ethanol, terpineol, and deionized water, preferably anhydrous ethanol. In some technical solutions, the mass ratio of the solvent to the high-entropy alloy solder can be 3:2.

[0031] A high-entropy alloy suspension can be obtained by ball milling high-entropy alloy solder, binder, and solvent. The ball milling time is 12-24 hours, preferably 12 hours. The ball milling speed is 200-350 r / min, preferably 300 r / min. The ball milling media are agate balls. The ball-to-material ratio can be adjusted as needed. As an example, the ball-to-material ratio (mass of ball milling media: total mass of high-entropy alloy solder, binder, and solvent) is 1:1-3. By first ball milling and mixing before preparing the suspension, not only are the elements in the high-entropy alloy powder more evenly dispersed, but the viscosity and solid content of the suspension can also be flexibly adjusted, thereby adapting to different coating methods and adjusting the coating thickness.

[0032] A high-entropy alloy slurry is uniformly coated onto the surface of the silicon carbide ceramic parts to be joined. The coating method includes, but is not limited to, spin coating, dip coating, spray coating, and screen printing coating.

[0033] The material composition of the silicon carbide ceramic component may be silicon carbide ceramic or silicon carbide composite material. Silicon carbide composite material includes, but is not limited to, carbon fiber reinforced silicon carbide and silicon carbide fiber reinforced silicon carbide.

[0034] Before coating the surface of the silicon carbide ceramic parts to be joined with a high-entropy alloy suspension, the silicon carbide ceramic parts can be pretreated. The purpose of pretreatment is to remove impurities such as silicon dioxide, carbon, and oil from the surface of the silicon carbide ceramic parts. For example, the surface layer of the silicon carbide ceramic parts can be ground off using a grinding machine, then polished, and finally ultrasonically cleaned with ethanol, acetone, or deionized water.

[0035] After coating the surfaces of two silicon carbide ceramic parts to be joined with a high-entropy alloy slurry, the joining surfaces are butt-jointed, and then dried and heat-treated for bonding. The heat treatment bonding can be performed in a high-temperature furnace, such as a sintering furnace or welding furnace. The heat treatment bonding temperature is 1200-1500℃, and the holding time is 30-120 min. In some technical solutions, the temperature is increased to the heat treatment bonding temperature at a heating rate of 5-20℃ / min. During the bonding process, the pressure is maintained at 5-40 MPa. The protective atmosphere for bonding is a vacuum or an inert gas. The inert gas can be argon. The butt joint of the silicon carbide ceramic parts can be completed using graphite or alumina molds. For example, bolts attached to the graphite or alumina mold can be used to apply a small pressure to ensure good contact between the bonding solder and the silicon carbide substrate.

[0036] In some technical solutions, the width (thickness) of the connection layer at the interface connecting silicon carbide ceramic parts is 5-200μm.

[0037] This invention is the first to apply the FeCoCrNiMo and FeCoCrNiMoTi high-entropy alloy system to the joining of silicon carbide ceramic parts, forming a joining interface with a bending strength higher than that of the silicon carbide matrix (315 MPa). This invention achieves the joining by first mechanically mixing the corresponding elemental powders of the high-entropy alloy, and then generating a high-entropy alloy joining layer through in-situ reaction. The process is simple, low-cost, and allows for easy adjustment of component content, making it highly valuable for practical applications. Furthermore, the interface between the joining joint and the substrate exhibits excellent bonding, a dense joint, and no obvious defects such as pores or cracks, resulting in a superior joining effect.

[0038] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0039] The four-point bending strength of the joint was tested according to the standard GB 6569-2006 Test Method for Bending Strength of Engineering Ceramics. The testing instrument used was a universal testing machine with a span of 10mm / 30mm and a head speed of 0.5mm / min.

[0040] Example 1

[0041] (1) Weigh 17.38g Fe, 18.33g Co, 16.18g Cr, 18.26g Ni and 29.85g Mo metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high entropy alloy solder.

[0042] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0043] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which had been ground, polished and ultrasonically cleaned. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1400℃, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined specimen.

[0044] like Figure 1 As shown, the high-entropy alloy solder after vacuum ball milling in Example 1 did not undergo significant alloying reaction and remained as a uniformly mixed elemental metal powder. Figure 2 As shown, the interface between the connector formed in Example 1 and the substrate is well bonded and diffusion occurs, but there is a lot of carbon at the interface, and the four-point bending strength of the connector is 158 MPa.

[0045] Example 2

[0046] (1) Weigh 17.38g Fe, 18.33g Co, 16.18g Cr, 18.26g Ni and 29.85g Mo metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high entropy alloy solder.

[0047] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0048] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which had been ground, polished and ultrasonically cleaned. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1300℃, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined test piece.

[0049] In this embodiment 2, due to the lower connection temperature, the interface between the formed connection joint and the substrate is generally well bonded, and the four-point bending strength of the joint is 94 MPa.

[0050] Example 3

[0051] (1) Weigh 17.38g Fe, 18.33g Co, 16.18g Cr, 18.26g Ni and 29.85g Mo metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high entropy alloy solder.

[0052] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0053] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which had been ground, polished and ultrasonically cleaned. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1500℃, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined test piece.

[0054] The interface between the connecting joint formed in this embodiment 3 and the substrate is well bonded, and the four-point bending strength of the joint is 125MPa.

[0055] Example 4

[0056] (1) Weigh 15.13g Fe, 15.96g Co, 14.08g Cr, 15.89g Ni, 25.98g Mo and 12.96g Ti metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high entropy alloy solder.

[0057] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0058] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which had been ground, polished and ultrasonically cleaned. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1400℃, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined specimen.

[0059] like Figure 3 As shown, the high-entropy alloy solder after vacuum ball milling in Example 4 was a uniformly mixed elemental metal powder, and no obvious alloying reaction occurred. Figure 4 As shown, the interface between the connector and the substrate formed in this embodiment is well bonded, with obvious diffusion, dense joints, and no obvious defects such as pores or cracks. The four-point bending strength of the connector is 315 MPa. A comparison with Example 1 shows that the addition of Ti significantly increases the reactivity between the solder and the substrate. Carbon in the substrate diffuses into the connecting layer and reacts with Ti to form TiC, resulting in better bonding at the interface and a very significant increase in strength.

[0060] Example 5

[0061] (1) Weigh 15.13g Fe, 15.96g Co, 14.08g Cr, 15.89g Ni, 25.98g Mo and 12.96g Ti metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high entropy alloy solder.

[0062] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0063] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined after grinding, polishing and ultrasonic cleaning. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 Pa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10 °C / min, the joining temperature was 1300 °C, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined specimen.

[0064] like Figure 5As shown, due to the low connection temperature, the interface between the connection joint formed in this embodiment 5 and the substrate is generally poor, with some defects such as holes. The four-point bending strength of the joint is 165MPa.

[0065] Example 6

[0066] (1) Weigh 15.13g Fe, 15.96g Co, 14.08g Cr, 15.89g Ni, 25.98g Mo and 12.96g Ti metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high entropy alloy solder.

[0067] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0068] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which had been ground, polished and ultrasonically cleaned. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1500℃, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined test piece.

[0069] like Figure 6 As shown, the interface between the connecting joint formed in this embodiment 6 and the substrate is well bonded, the joint is dense, and there are no obvious defects such as holes or cracks. The four-point bending strength of the joint is 215MPa.

[0070] Comparative Example 1

[0071] Weigh 20g of commercially available atomized FeCoCrNiMo high-entropy alloy powder, 30g of ethanol, 1.25g of polyvinyl butyral, and 25g of agate balls, and place them in a ball mill for 12 hours to prepare a high-entropy alloy suspension. The high-entropy alloy suspension is uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which have undergone grinding, polishing, and ultrasonic cleaning. The two surfaces to be joined are aligned and clamped using a graphite clamp at a pressure of 25MPa. After drying in an oven, they are placed in a sintering furnace for joining. The heating rate is 10℃ / min, the joining temperature is 1400℃, and the holding time is 60min. The joining is performed in a vacuum environment to obtain the joined specimen.

[0072] like Figure 7As shown, the interface between the joint formed in Comparative Example 1 and the substrate is weak, resulting in poor bonding. A large amount of carbon accumulates at the interface, and the four-point bending strength of the joint is only 51 MPa. A comparison with Example 1 reveals that the alloyed high-entropy alloy powder exhibits a delayed diffusion effect, leading to a slow element diffusion rate. A large amount of carbon generated after the reaction between the substrate and the solder accumulates at the interface, affecting the bonding between the solder and the substrate. This invention first mechanically mixes the high-entropy alloy elements and then generates a high-entropy alloy bonding layer through in-situ reaction. This method not only facilitates the adjustment of the solder composition but also promotes the formation of a good interface reaction layer between the high-entropy alloy and the silicon carbide substrate, improving the bonding strength.

[0073] Comparative Example 2

[0074] 20g of commercially available atomized AlFeCoCrNi high-entropy alloy powder, 30g of ethanol, 1.25g of polyvinyl butyral, and 25g of agate balls were weighed and ball-milled for 12 hours to prepare a high-entropy alloy suspension. The high-entropy alloy suspension was uniformly coated onto the surfaces of two silicon carbide ceramic parts to be joined, which had undergone grinding, polishing, and ultrasonic cleaning. The two surfaces to be joined were aligned and clamped using graphite clamps at a pressure of 25MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1400℃, and the holding time was 60min. The joining was performed in a vacuum environment. Due to insufficient strength, the sample was damaged during processing, and the joining effect was not achieved.

[0075] Comparative Example 3

[0076] (1) Weigh 10.7g Al, 23.3g Fe, 22.1g Co, 20.6g Cr and 23.3g Ni metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high-entropy alloy solder.

[0077] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0078] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which had been ground, polished and ultrasonically cleaned. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1400℃, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined specimen.

[0079] The interface between the joint formed in Comparative Example 3 and the substrate was poor, and the four-point bending strength of the joint was 55 MPa.

[0080] Comparative Example 4

[0081] (1) Weigh 9.0g Al, 19.6g Fe, 18.6g Co, 17.3g Cr, 19.6g Ni and 15.9g Ti metal powder, 3g ethanol and 309g stainless steel balls, add them to the vacuum ball mill jar in a vacuum glove box and place them in the ball mill for 36h. Stop the machine for 1h every 5h of rotation. After the ball milling is completed, place it in a vacuum oven at 80℃ and dry for 24h to obtain high entropy alloy solder.

[0082] (2) Weigh 20g of high-entropy alloy solder, 30g of ethanol, 1.25g of polyvinyl butyral and 25g of agate balls, place them in a ball mill and ball mill for 12h to prepare a high-entropy alloy suspension.

[0083] (3) A high-entropy alloy suspension was uniformly coated on the surfaces of two silicon carbide ceramic parts to be joined, which had been ground, polished and ultrasonically cleaned. The two surfaces to be joined were aligned and clamped with a graphite clamp at a pressure of 25 MPa. After drying in an oven, the parts were placed in a sintering furnace for joining. The heating rate was 10℃ / min, the joining temperature was 1400℃, and the holding time was 60 min. The joining was carried out in a vacuum environment to obtain the joined specimen.

[0084] The interface between the joint formed in Comparative Example 4 and the substrate is generally good, and the four-point bending strength of the joint is 124 MPa.

Claims

1. A method for joining silicon carbide ceramic parts using high-entropy alloy solder, characterized in that, The method includes: Various elemental metal powders were weighed according to equiatomic percentages and a process control agent was added. The mixture was ball-milled under vacuum or argon atmosphere, and then dried to remove the process control agent, yielding a high-entropy alloy solder. The high-entropy alloy solder consisted of elemental metal powders of Fe, Co, Cr, Ni, Mo, and Ti, with each element having the same atomic percentage. The process control agent was anhydrous ethanol, and the mass ratio of the process control agent to the elemental metal powders was 3%-10%. High-entropy alloy solder is mixed with binder and solvent to form high-entropy alloy slurry; Then, the high-entropy alloy slurry is uniformly coated onto the surface of the silicon carbide ceramic parts to be joined; After the silicon carbide ceramic parts coated with high-entropy alloy paste are joined together, heat treatment is performed to form a high-entropy alloy connection layer in situ, resulting in a silicon carbide connector; wherein, the heat treatment connection temperature is 1400-1500℃.

2. The method according to claim 1, characterized in that, The particle size of the metal element powder is 1-20 μm.

3. The method according to claim 1, characterized in that, The material of the silicon carbide ceramic part is one or more of silicon carbide, carbon fiber reinforced silicon carbide, and silicon carbide fiber reinforced silicon carbide.

4. The method according to claim 1, characterized in that, The adhesive is at least one of polyvinyl butyral and polyvinyl alcohol, and the solvent is at least one of anhydrous ethanol, terpineol, and deionized water.

5. The method according to claim 1, characterized in that, The mass ratio of the high-entropy alloy solder, solvent and binder is (40-60):(40-60):(1-5).

6. The method according to claim 1, characterized in that, The heat treatment connection is held for 30-120 minutes, at a pressure of 5-40 MPa, in a vacuum or argon atmosphere.

7. The method according to claim 6, characterized in that, Heat to the heat treatment connection temperature at a heating rate of 5-20℃ / min.

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