SiC cladding joint preparation method and SiC cladding joint

Abstract

The invention discloses a preparation method of a SiC cladding joint and the SiC cladding joint, and the preparation method comprises the following steps: S1, preparing connection slurry: adding a powder raw material into a mixture formed by resin and an organic solvent, and uniformly mixing; s2, the SiC connecting pieces to be connected are coated with the connecting slurry, the two SiC connecting pieces to be connected are in butt joint, and a prefabricated connecting assembly is formed; s3, the prefabricated connecting assembly is placed at the temperature of 1200-1650 DEG C for pressureless sintering, and a connecting assembly is formed; and S4, the connecting assembly is subjected to heat treatment, so that a non-corrosion-resistant and non-oxidation-resistant phase in a weld joint of the connecting assembly is converted into a corrosion-resistant and antioxidant phase. According to the preparation method of the SiC cladding connector, the connection temperature and pressure of SiC ceramics are reduced, and reliable connection of a thin-wall and large-length-diameter-ratio SiC cladding can be achieved; through heat treatment, a non-corrosion-resistant phase is effectively prevented from being in direct contact with the external environment, and the reliability of a joint welding seam is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of ceramic material joining technology, and in particular to a method for preparing a SiC clad joint and a SiC clad joint. Background Technology

[0002] Silicon carbide (SiC) ceramics have high melting point, corrosion resistance, neutron radiation resistance and excellent mechanical properties, making them an excellent candidate material for nuclear fuel cladding. However, due to their thin walls, large aspect ratio, high melting point and low self-diffusion coefficient, SiC fuel cladding and encapsulation present great challenges.

[0003] Current joining methods mainly include metal / alloy brazing, glass-ceramic joining, MAX phase joining (where M is an early transition metal, A is a main group element, and X is C or N), and reactive joining. Among these, using low-melting-point solders such as metals and glass can easily reduce the high-temperature performance and corrosion resistance of ceramic connectors; using ceramic solders requires a harsh high-temperature and high-pressure joining process, which is not conducive to the application of ceramic joining technology; MAX phase joining can obtain ceramic connectors with excellent high-temperature and corrosion resistance and high connection strength, but usually requires pressure. Due to the large mismatch in the thermal expansion coefficients between the MAX phase interlayer and the SiC matrix, the joint can easily develop large residual stresses, thus reducing the joint's performance; with reactive joining, the main phase of the joining layer is SiC, so there is no mismatch in the thermal expansion coefficients between the interlayer and the matrix, but the presence of residual silicon will affect the overall performance of the SiC joint, especially its high-temperature, corrosion, and radiation resistance.

[0004] Therefore, there is an urgent need to develop a reliable connection technology for structural components, and to develop a joint with good overall performance after connection, so as to effectively expand the application fields of ceramic connectors. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an improved method for preparing SiC clad joints and the SiC clad joints obtained therefrom.

[0006] The technical solution adopted by this invention to solve its technical problem is: to provide a method for preparing a SiC cladding joint, comprising the following steps: S1. Preparation of bonding slurry: Add the powder raw materials to the mixture formed by the resin and organic solvent, and mix evenly; The mass ratio of the powder raw material to the mixture is 5:19 to 26; the powder raw material includes at least one of silicon carbide, carbon, titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, chromium, vanadium, and niobium. S2. Apply the connecting slurry to the SiC connectors to be connected, and then butt the two SiC connectors to be connected to form a prefabricated connection assembly of SiC connector-connecting slurry-SiC connector; S3. The prefabricated connecting assembly is sintered at 1200℃~1650℃ to form a connecting assembly; S4. The connecting assembly is subjected to heat treatment at 800℃~1500℃ to transform the non-corrosion-resistant and non-oxidation-resistant phase in the weld of the connecting assembly into a corrosion-resistant and oxide-resistant phase.

[0007] Preferably, in the mixture, the mass ratio of resin to organic solvent is 5:95 to 10:90.

[0008] Preferably, the organic solvent includes at least one of anhydrous ethanol, acetone, ethylene glycol, and xylene; the resin includes at least one of phenolic resin and epoxy resin.

[0009] Preferably, the particle size of the powder raw material is 0.01μm to 10μm, and the purity is 99% to 99.9999%.

[0010] Preferably, the powder raw material includes silicon carbide and at least one elemental powder, wherein the mass ratio of the elemental powder to the silicon carbide is 10:90 to 30:70; the elemental powder includes at least one of carbon, titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, chromium, vanadium, and niobium.

[0011] Preferably, in step S3, during sintering, the heating rate is controlled at 5℃ / min to 20℃ / min; or, the heating rate is controlled at 20℃ / min to 200℃ / min.

[0012] Preferably, in step S3, the sintering environment is a helium environment, a nitrogen environment, an argon environment, or a mixture of the aforementioned gases.

[0013] Preferably, in step S3, the sintering is carried out in a pressureless sintering furnace, a brazing furnace, or a tube furnace.

[0014] Preferably, in step S3, the sintering is carried out in a hot press furnace, a spark plasma sintering furnace, or a hot isostatic pressing furnace.

[0015] Preferably, in step S4, the heat treatment is performed in a carbon atmosphere; the carbon atmosphere is provided by graphite.

[0016] Preferably, the SiC connector is a SiC clad tube and a SiC end plug.

[0017] This invention also provides a SiC clad connector, prepared by any one of the SiC clad connector preparation methods described above, wherein the SiC clad connector has a connection strength of 150 MPa to 200 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -10 Pa·m 3 / s~1.0×10 -14 Pa·m 3 / s.

[0018] The beneficial effects of the present invention are as follows: Compared with the high temperature (≥1800℃) and high pressure (≥20MPa) required for traditional silicon carbide ceramic connection, the SiC cladding joint preparation method of the present invention reduces the connection temperature and pressure of SiC ceramic, and can realize reliable connection of thin-walled, high aspect ratio SiC cladding; heat treatment effectively avoids direct contact between non-corrosive phases and the external environment, and effectively improves the reliability of the joint weld. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is an electron micrograph of the SiC connector obtained in Example 1 of this invention; Figure 2 This is an electron micrograph of the SiC connector obtained in Example 1 of this invention after corrosion in an aqueous environment; Figure 3 This is an electron micrograph of the SiC connector obtained in Comparative Example 1 of this invention; Figure 4 This is an electron micrograph of the SiC connector prepared in Comparative Example 1 of this invention after corrosion in an aqueous environment. Detailed Implementation

[0020] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] The SiC cladding joint preparation method of the present invention may include the following steps: S1. Preparation of bonding slurry: Add the powder raw material to the mixture formed by the resin and organic solvent, and mix evenly.

[0022] The mass ratio of powder raw materials to the mixture is 5:19 to 26. The powder raw materials include at least one of silicon carbide, carbon, titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, chromium, vanadium, and niobium; the preferred particle size of the powder raw materials is 0.01 μm to 10 μm, and the purity is 99% to 99.9999%.

[0023] The purpose of the mixture formed by the organic solvent is to transform the powder raw material into a slurry with better flowability, facilitating subsequent operations and control of weld thickness. In the mixture, the mass ratio of resin to organic solvent is 5:95 to 10:90.

[0024] The organic solvent includes at least one of anhydrous ethanol, acetone, ethylene glycol, and xylene. The resin is used to provide a carbon source and may include at least one of phenolic resin and epoxy resin.

[0025] Examples of powder raw materials include at least two of silicon carbide, carbon, titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, chromium, vanadium, and niobium, wherein at least silicon carbide is included. Silicon carbide powder serves as an inert filler, while other non-metallic and metallic phases act as reactive phases during heat treatment, promoting reactions and phase transport within the weld itself and between the weld and the matrix.

[0026] In embodiments where the powder raw materials include elemental powders (at least one of carbon, titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, chromium, vanadium, and niobium) and silicon carbide, the mass ratio of elemental powders to silicon carbide is 10:90 to 30:70.

[0027] S2. Apply the bonding slurry to the SiC connectors to be connected, and then butt the two SiC connectors to be connected to form a prefabricated connection assembly with a sandwich structure of SiC connector-bonding slurry-SiC connector.

[0028] For any two SiC connectors to be joined, the bonding paste can be applied to the joint surface of one of the SiC connectors, ensuring sufficient coating thickness to meet the connection requirements. Alternatively, the bonding paste can be applied to the joint surfaces of both SiC connectors, so that after the SiC connectors are joined, the bonding paste layer in the middle has sufficient coating thickness to meet the connection requirements.

[0029] S3. The prefabricated connecting components are sintered at 1200℃~1650℃ for 10min~120min to form the connecting components.

[0030] The sintering of prefabricated connecting components enables welding connections between SiC connectors. The sintering environment can be helium, nitrogen, argon, or a mixture of these gases, depending on the specific requirements. For example, for connectors such as fuel rods, where the connection process requires helium filling, sintering is performed in a helium environment. For connection processes without helium filling requirements, sintering can be performed in at least one of nitrogen or argon gas environments.

[0031] For sintering bonding processes requiring reactive gas or liquid assistance, at least one of silicon vapor or liquid silicon can be used to provide the sintering environment. To avoid the influence of the external environment on the quality of the bonded components, especially the effects of the reaction of oxygen and nitrogen in the air, the ambient vacuum level before sintering bonding needs to be controlled at 10. -5 ~10 Pa.

[0032] Sintering can be carried out in a pressureless sintering furnace, brazing furnace, or tube furnace, or in a hot press furnace, electric discharge plasma sintering furnace, or hot isostatic pressing furnace. For SiC connectors with complex structures (complex shapes that deform under pressure), a pressureless sintering furnace, brazing furnace, or tube furnace is preferred. For SiC connectors with simple structures (simple shapes) that can withstand pressure, a hot press furnace, electric discharge plasma sintering furnace, or hot isostatic pressing furnace is preferred.

[0033] During sintering, the heating rate is controlled between 5℃ / min and 20℃ / min; or, between 20℃ / min and 200℃ / min. The heating rate is selected according to the different sintering equipment. For equipment using graphite, tungsten / molybdenum, or other electrode heating methods, the heating rate is controlled between 5℃ / min and 20℃ / min; for high-efficiency heating methods such as discharge plasma sintering, the heating rate can be controlled between 20℃ / min and 200℃ / min.

[0034] In order to control the composition of the periphery of the corrosion-sensitive and oxidized weld in the connecting assembly, the connecting assembly needs to undergo a further heat treatment.

[0035] S4. Place the connecting components in a heat treatment environment of 800℃~1500℃ for 10min~120min to transform the non-corrosion and non-oxidation-resistant phases in the weld of the connecting components into corrosion-resistant and oxide-resistant phases, thereby improving corrosion resistance. The phase transformation also helps to alleviate the degree of thermal expansion mismatch between the joint and the substrate.

[0036] The heat treatment is conducted in a carbon atmosphere, which facilitates the conditioning of the phase composition around the weld into corrosion-resistant and oxidation-resistant carbides. The carbon atmosphere is provided by graphite. Specifically, the carbon atmosphere can be provided by a graphite heating element, or by placing graphite blocks or powder.

[0037] In the above preparation method, a prefabricated connector assembly with a "SiC connector-connecting slurry-SiC connector" sandwich structure is formed by coating a connecting slurry onto the surface of the SiC connector (i.e., ceramic part) and bonding it. The connecting slurry serves as an intermediate auxiliary layer to promote phase transport and chemical reaction between the ceramic substrates. The prefabricated connector assembly is then placed in a connecting device (i.e., sintering equipment) and connected at 1200℃~1650℃ for 10min~120min to obtain the ceramic connector (i.e., SiC cladding joint). This connecting process ensures that the ceramic connector has sufficient strength and effective interfacial bonding. The ceramic connector is then further subjected to a next stage of heat treatment at 800℃~1500℃ for 10min~120min. This heat treatment stage aims to transform the non-corrosion-resistant and non-oxidation-resistant phases in the weld into corrosion-resistant and oxide-resistant phases. This phase transformation also helps to alleviate the thermal expansion mismatch between the joint and the substrate, thus obtaining the final joint.

[0038] In one embodiment, the two SiC connectors to be connected are a SiC clad tube and a SiC end plug. After steps S2 to S4, a SiC clad tube with at least one end sealed by the SiC end plug is obtained. In other embodiments, the two SiC connectors to be connected can also be two SiC clad tube segments.

[0039] The SiC clad joint prepared by the method of the present invention has a connection strength of 150 MPa to 200 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -10 Pa·m 3 / s~1.0×10 -14 Pa·m 3 / s.

[0040] The corrosion resistance of SiC clad joints can be significantly improved, especially when the weld contains corrosion-sensitive phases, such as non-metallic silicon and reactive metallic phases. Through heat treatment and carbonization during the manufacturing process, these phases can be transformed into corrosion-resistant and oxidation-resistant carbides, such as SiC. This allows SiC clad joints to maintain a corrosion resistance of 1.0 × 10⁻⁶ after corrosion in ultrapure water at 18.6 MPa and 360 °C. -10 ~1.0×10 -14 Pa·m 3 / s helium leak rate.

[0041] The present invention will be further described below through specific embodiments.

[0042] Example 1: A bonding slurry was prepared by mixing carbon (99% purity, 500nm particle size), phenolic resin (purity: solid content ~70%, Shanghai Maclean Biochemical Technology Co., Ltd.) and ethylene glycol in a mass ratio of 1:2:18.8 and stirring magnetically (300r / min) for 2 hours.

[0043] A bonding slurry is coated onto the surface of SiC ceramic and bonded together to form a prefabricated connector with a sandwich structure of "SiC ceramic-bonding slurry-SiC ceramic". The prefabricated connector is placed in a pressureless sintering furnace and heated to 1500°C at a rate of 10°C / min in flowing argon gas, and held for 120 min to obtain the SiC ceramic connector, i.e., the SiC joint.

[0044] The SiC connector was heat-treated at 1500℃ for 60 minutes, with the connector placed in the center of a graphite heating ring during the treatment. The microstructure of the heat-treated SiC connector is shown below. Figure 1 As shown, the black phase in the weld is carbon, and the gray phase is SiC. After corroding the SiC joint in a water environment at 18.6 MPa and 360℃ for 30 days, the results are as follows... Figure 2 As shown, the black carbon and gray SiC phases in the weld showed no significant changes after corrosion.

[0045] The SiC joint has a shear strength of 170 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -13 Pa·m 3 / s. After 30 days of corrosion in a 18.6 MPa, 360℃ water environment, the helium leakage rate of the SiC joint remained at 1.0×10. - 13 Pa·m 3 / s.

[0046] Example 2: The bonding slurry was prepared by mixing activated carbon (99% purity, 300nm particle size), silicon carbide powder (99% purity, 3μm particle size), phenolic resin (purity: solid content ~70%, Shanghai Maclean Biochemical Technology Co., Ltd.) and ethylene glycol in a mass ratio of 1:3.7:2:18.8 and stirring magnetically (300r / min) for 2 h.

[0047] A bonding slurry is coated onto the surface of SiC ceramic and bonded together to form a prefabricated connector with a sandwich structure of "SiC ceramic-bonding slurry-SiC ceramic". The prefabricated connector is placed in a pressureless sintering furnace and heated to 1650°C in flowing argon gas and held for 120 minutes to obtain the SiC ceramic connector, i.e., the SiC joint.

[0048] The SiC connector was placed in the center of a graphite heating ring and subjected to further heat treatment at 1500℃ for 60 min. The heat-treated SiC connector exhibited a shear strength of 200 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -12 Pa·m 3 / s. After 30 days of corrosion in a 18.6 MPa, 360℃ water environment, the helium leakage rate of the SiC joint remained at 1.0×10. -12 Pa·m 3 / s.

[0049] Example 3: A bonding slurry was prepared by mixing titanium (99% purity, 5μm particle size), silicon carbide powder (99% purity, 3μm particle size), phenolic resin (purity: solid content ~70%, Shanghai Maclean Biochemical Technology Co., Ltd.) and ethylene glycol in a mass ratio of 1:4:5:21 and stirring magnetically (300r / min) for 2 h.

[0050] A bonding slurry was coated onto the surface of SiC ceramic, and the two were bonded together to form a prefabricated connector with a "SiC ceramic-bonding slurry-SiC ceramic" sandwich structure. This prefabricated connector was placed in a pressureless sintering furnace and heated to 1500℃ in flowing argon gas, held for 120 min, to obtain the SiC joint. The SiC joint was then placed in the center of a graphite heating ring for further heat treatment at 1000℃ for 10 min. The SiC joint exhibited a shear strength of 150 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -11 Pa·m 3 After 30 days of corrosion in a 18.6 MPa, 360℃ water environment, the helium leakage rate of the SiC joint remained at 1.0 × 10⁻⁶. -11 Pa·m 3 / s.

[0051] Example 4: A bonding slurry was prepared by mixing titanium (99% purity, 0.01μm particle size), silicon carbide powder (99% purity, 0.3μm particle size), phenolic resin (purity: solid content ~70%, Shanghai Maclean Biochemical Technology Co., Ltd.) and ethylene glycol in a mass ratio of 1:4:1:18 and stirring magnetically (300r / min) for 2 h.

[0052] A bonding slurry was coated onto the surface of SiC ceramic, and the two were bonded together to form a prefabricated connector with a "SiC ceramic-bonding slurry-SiC ceramic" sandwich structure. This prefabricated connector was placed in a pressureless sintering furnace and heated to 1400℃ in flowing argon gas, held for 120 min, to obtain the SiC joint. The SiC joint was then placed in the center of a graphite heating ring for further heat treatment at 800℃ for 10 min. The SiC joint exhibited a shear strength of 180 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -13 Pa·m 3 / s. After 30 days of corrosion in a 18.6 MPa, 360℃ water environment, the helium leakage rate of the SiC joint remained at 1.0×10. -13 Pa·m 3 / s.

[0053] Example 5: A bonding slurry was prepared by mixing titanium (99% purity, 0.01μm particle size), phenolic resin (purity: solid content ~70%, Shanghai Maclean Biochemical Technology Co., Ltd.) and ethylene glycol in a mass ratio of 2:1:9 and stirring magnetically (300r / min) for 2 h.

[0054] A bonding slurry was coated onto the surface of SiC ceramic, and the two were bonded together to form a prefabricated connector with a "SiC ceramic-bonding slurry-SiC ceramic" sandwich structure. This prefabricated connector was placed in a pressureless sintering furnace and heated to 1200℃ in flowing argon gas, held for 120 min, to obtain the SiC joint. The SiC joint was then placed in the center of a graphite heating ring for further heat treatment at 800℃ for 30 min. The SiC joint exhibited a shear strength of 250 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -14 Pa·m 3 / s. After 30 days of corrosion in a 18.6 MPa, 360℃ water environment, the helium leakage rate of the SiC joint remained at 1.0×10. -14 Pa·m 3 / s.

[0055] Example 6: A bonding slurry was prepared by mixing metallic Nb (99% purity, 1μm particle size), phenolic resin (purity: solid content ~70%, Shanghai Maclean Biochemical Technology Co., Ltd.) and ethylene glycol in a mass ratio of 2:1:9 and stirring magnetically (300 r / min) for 2 h.

[0056] A bonding slurry was coated onto the surface of SiC ceramic, and a prefabricated connector with a "SiC ceramic-bonding slurry-SiC ceramic" sandwich structure was formed. This prefabricated connector was placed in a pressureless sintering furnace and heated to 1500℃ in flowing argon gas, held for 120 min, to obtain the SiC joint. The SiC joint was then placed in the center of a graphite heating ring for further heat treatment at 1000℃ for 30 min. The shear strength of this SiC joint at room temperature was 200 MPa, and the helium leakage rate was 1.0 × 10⁻⁶. -14 Pa·m 3 / s. After 30 days of corrosion in a 18.6 MPa, 360℃ water environment, the helium leakage rate of the SiC joint remained at 1.0×10. -14 Pa·m 3 / s.

[0057] Comparative Example 1 A bonding slurry was prepared by mixing carbon (99% purity, 500nm particle size), phenolic resin (purity: solid content ~70%, Shanghai Maclean Biochemical Technology Co., Ltd.) and ethylene glycol in a mass ratio of 1:2:18.8 and stirring magnetically (300r / min) for 2 hours.

[0058] A bonding slurry is coated onto the surface of SiC ceramic and bonded together to form a prefabricated connector with a sandwich structure of "SiC ceramic-bonding slurry-SiC ceramic". The prefabricated connector is placed in a pressureless sintering furnace and heated to 1500°C at a rate of 10°C / min in flowing argon gas, and held for 120 min to obtain the SiC ceramic connector, i.e., the SiC joint.

[0059] The microstructure of the SiC connector is as follows: Figure 3 As shown. In Figure 3 In the intermediate layer weld, the white phase is residual Si, and the gray phase is SiC.

[0060] After corroding the SiC joint in a water environment at 18.6 MPa and 360℃ for 30 days, the results are as follows: Figure 4 As shown, the white residual Si in the weld is clearly corroded.

[0061] A comparison of the microstructures of the SiC connectors prepared in Example 1 and Comparative Example 1 shows that after heat treatment, the non-metallic silicon in the SiC connector of Example 1 is transformed into corrosion-resistant and oxidation-resistant SiC, which improves the corrosion resistance of the SiC connector and ensures the helium leakage rate of the SiC connector.

[0062] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a SiC clad joint, characterized in that, Includes the following steps: S1. Preparation of bonding slurry: Add the powder raw materials to the mixture formed by the resin and organic solvent, and mix evenly; The mass ratio of the powder raw material to the mixture is 5:19 to 26; the powder raw material includes at least one of silicon carbide, carbon, titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, chromium, vanadium, and niobium. S2. Apply the connecting slurry to the SiC connectors to be connected, and then butt the two SiC connectors to be connected to form a prefabricated connection assembly of SiC connector-connecting slurry-SiC connector; S3. The prefabricated connecting assembly is sintered at 1200℃~1650℃ to form a connecting assembly; S4. The connecting assembly is subjected to heat treatment at 800℃~1500℃ to transform the non-corrosion-resistant and non-oxidation-resistant phase in the weld of the connecting assembly into a corrosion-resistant and oxide-resistant phase.

2. The method for preparing a SiC clad joint according to claim 1, characterized in that, In the mixture, the mass ratio of resin to organic solvent is 5:95 to 10:90; The organic solvent includes at least one of anhydrous ethanol, acetone, ethylene glycol, and xylene; The resin includes at least one of phenolic resin and epoxy resin.

3. The method for preparing a SiC clad joint according to claim 1, characterized in that, The particle size of the powder raw material is 0.01μm to 10μm, and the purity is 99% to 99.9999%.

4. The method for preparing a SiC clad joint according to claim 1, characterized in that, The powder raw material includes silicon carbide and at least one elemental powder, wherein the mass ratio of the elemental powder to the silicon carbide is 10:90 to 30:70; the elemental powder includes at least one of carbon, titanium, zirconium, hafnium, tantalum, tungsten, molybdenum, chromium, vanadium and niobium.

5. The method for preparing a SiC clad joint according to claim 1, characterized in that, In step S3, during sintering, the heating rate is controlled at 5℃ / min to 20℃ / min; or, the heating rate is controlled at 20℃ / min to 200℃ / min.

6. The method for preparing a SiC clad joint according to claim 1, characterized in that, In step S3, the sintering environment is a helium environment, a nitrogen environment, an argon environment, or a mixture of the aforementioned gases; and / or, in step S3, the sintering is carried out in a pressureless sintering furnace, a brazing furnace, or a tube furnace.

7. The method for preparing a SiC clad joint according to claim 1, characterized in that, In step S3, the sintering is carried out in a hot press furnace, a discharge plasma sintering furnace, or a hot isostatic pressing furnace.

8. The method for preparing a SiC clad joint according to claim 1, characterized in that, In step S4, the heat treatment is performed in a carbon atmosphere; the carbon atmosphere is provided by graphite.

9. The method for preparing a SiC clad joint according to any one of claims 1-8, characterized in that, The SiC connector consists of a SiC clad tube and a SiC end plug.

10. A SiC-clad connector, characterized in that, The SiC clad joint is prepared by the method described in any one of claims 1-9, and the SiC clad joint has a connection strength of 150 MPa to 200 MPa at room temperature and a helium leakage rate of 1.0 × 10⁻⁶. -10 Pa·m 3 / s~1.0×10 -14 Pa·m 3 / s.

Images