A SiC ceramic-based composite flow channel insert, its preparation method and application

Abstract

This invention relates to the field of flow channel insert technology in fusion reactor blanket structures, specifically to a SiC ceramic-based composite flow channel insert, its preparation method, and its application. The invention involves depositing a pyrolytic carbon interface on a SiC prefabricated fabric to obtain a SiC prefabricated fabric with a pyrolytic carbon interface; mixing SiC powder, ZrO2 powder, and Al2O3 powder to obtain a filler powder mixture; mixing the filler powder mixture with water and then adding polycarbosilane to obtain a mixed slurry; coating the mixed slurry onto the SiC prefabricated fabric; densifying the silicon carbide substrate deposited on the SiC prefabricated fabric; and after finishing, preparing a silicon carbide coating using chemical vapor deposition to obtain the SiC ceramic-based composite flow channel insert. This invention aims to further enhance the thermal insulation and electrical insulation properties of the SiC ceramic-based composite flow channel insert, increase the average temperature at the outlet of the flow channel insert, reduce the pressure drop of the magnetohydrodynamic fluid, achieve high-efficiency energy conversion, and simultaneously ensure the long-term safe operation of the reactor.

Description

Technical Field

[0001] This invention relates to the field of flow channel insert technology in fusion reactor blanket structure, specifically to a SiC ceramic-based composite flow channel insert, its preparation method, and its application. Background Technology

[0002] A typical fusion-resistant blanket system consists of four parts: a steel wall, a gas gap flow region, flow channel inserts, and a central metal flow region. The outer steel wall of the blanket system directly faces the extremely high temperature of the reactor core. The gas gap flow region provides boundary conditions for convective heat transfer through inert gas. The inner metal fluid is primarily responsible for heat exchange, while the flow channel inserts are components nested within the flow channels, dividing the fluid into two channels and providing thermal and electrical insulation within the blanket system.

[0003] In the blanket system, an efficient thermal management system ensures the safe and stable operation of the reactor, making the insulation of the flow channel components a critical factor. Good insulation performance can prevent heat from spreading uncontrollably from the high-temperature plasma region to other components of the reactor, preventing material degradation, structural deformation, or even catastrophic failures caused by localized overheating, thus ensuring the integrity of the overall reactor structure. At the same time, it helps maintain the high-temperature environment of the plasma, reduces unnecessary heat loss, improves energy utilization efficiency, and enables the fusion reaction to proceed continuously and stably.

[0004] In addition, because the fusion reaction occurs in a strong magnetic field environment and the liquid lithium-lead metal flows at high speed within the flow channels, electromagnetic induction is unavoidable. If the flow channel inserts lack sufficient insulation, conductive particles in the coolant are easily induced to generate currents under the influence of the magnetic field, leading to strong electromagnetic interference. This not only disrupts the normal flow of the coolant, significantly increases flow resistance, causes a greater pressure drop, and affects the efficiency of the cooling system, but may also trigger electrochemical reactions, corroding the flow channel inserts and connected components, reducing the reliability and lifespan of the entire system. Therefore, ensuring that the flow channel inserts possess excellent insulation properties is a necessary condition for shielding electromagnetic interference, maintaining stable coolant flow, and ensuring the long-term safe operation of the reactor.

[0005] Currently, the materials used in flow channel components are usually SiC ceramic matrix composites with high thermal stability. However, with the development of fusion reactors, higher requirements have been placed on the performance of SiC ceramic matrix composites, and it is necessary to further improve the thermal insulation and insulation properties of existing SiC ceramic composite flow channel components. Summary of the Invention

[0006] To address the shortcomings of the existing technology, the present invention aims to provide a SiC ceramic-based composite flow channel insert, its preparation method, and its application. The present invention aims to further enhance the thermal insulation and electrical insulation properties of the SiC ceramic-based composite flow channel insert, increase the average temperature at the outlet of the flow channel insert, reduce the pressure drop of the magnetohydrodynamic fluid, achieve high-efficiency energy conversion, and ensure the long-term safe operation of the reactor.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for preparing a SiC ceramic-based composite flow channel insert includes the following steps:

[0009] A pyrolytic carbon interface is deposited on a multilayer SiC prefabricated fabric using a chemical vapor infiltration process, resulting in a SiC prefabricated fabric with a pyrolytic carbon interface. This effectively protects the silicon carbide fibers and improves their strength and toughness. Compared with chemical vapor deposition or other processes, chemical vapor infiltration can uniformly deposit pyrolytic carbon in complex shapes and porous structures, effectively improving the mechanical properties and thermal shock resistance of the composite material, and is suitable for the complex structure of fiber prefabricated structures.

[0010] SiC powder and functional particles with low thermal conductivity and radiation resistance are ball-milled and mixed. The functional particles with low thermal conductivity and radiation resistance are ZrO2 powder and Al2O3 powder. The mixed powder is ground and sieved to obtain a filler powder mixture. The filler powder mixture is mixed with water, and then polycarbosilane is added and stirred to obtain a mixed slurry. Alumina and zirconium oxide have good chemical stability at high temperatures, which can effectively reduce the thermal conductivity of the SiC matrix, thereby improving the thermal insulation of the composite material. At the same time, zirconium oxide has low thermal conductivity and high coefficient of thermal expansion, which can alleviate thermal stress and reduce thermal shock damage. In addition, the coefficient of thermal expansion of alumina is close to that of SiC, which helps to reduce interfacial thermal stress and further improve thermal shock resistance.

[0011] The mixed slurry is uniformly coated onto a SiC prefabricated fabric with a pyrolytic carbon interface. Then, the SiC prefabricated fabric coated with the mixed slurry is densified to deposit a silicon carbide substrate, thereby obtaining a SiC ceramic-based composite flow channel insert blank.

[0012] After processing the SiC ceramic-based composite flow channel insert blank, a β-phase silicon carbide coating is prepared by high-temperature chemical vapor deposition to obtain the SiC ceramic-based composite flow channel insert.

[0013] This invention introduces zirconia and alumina functional particles through a coating method. Finite element analysis revealed the thermal conductivity of the composite material, showing that the thermal conductivity of the ceramic-based composite flow channel insert is no higher than 5 W / m·K, indicating excellent thermal insulation and thermal conductivity. Good thermal insulation increases the average temperature of the liquid lithium-lead metal fluid at the outlet of the flow channel insert, thereby improving thermal efficiency. Simultaneously, it reduces the structural thermal stress of the first wall, ensuring structural safety. Furthermore, good thermal insulation helps maintain a stable flow field and reduces the additional resistance generated by the flowing liquid lithium-lead metal fluid, thus reducing the pressure drop of the magnetohydrodynamic fluid and improving energy conversion efficiency.

[0014] In a preferred embodiment of the present invention, the volume ratio of SiC powder, ZrO2 powder and Al2O3 powder is 10:60~80:10~30, the mass ratio of the filler powder mixture to water is 4~6:1, and the mass fraction of polycarbosilane in the filler powder mixture is 50%~60%.

[0015] In a preferred embodiment of the present invention, the deposition thickness of the pyrolytic carbon interface is 100 nm to 400 nm. When depositing the pyrolytic carbon interface, the precursor gas source is propylene, the diluent gas is argon, the deposition temperature is 850 °C to 950 °C, the deposition pressure is 2 kPa to 5 kPa, and the deposition time is 80 h to 250 h.

[0016] In a preferred embodiment of the present invention, the densification treatment method is a chemical vapor infiltration process or a precursor pyrolysis method, and the porosity of the silicon carbide matrix after densification treatment is 5%~15%.

[0017] In a preferred embodiment of the present invention, when densifying the silicon carbide matrix using chemical vapor infiltration, the precursor gas source is trichloromethylsilane, the carrier gas is argon, and the dilution gas is hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 8.5~10:1. The hydrogen flow rate is 1L / min~1L / min, the hydrogen flow rate is 1L / min~2L / min, and the argon flow rate is 3L / min~4L / min. The deposition temperature is 900℃~1100℃, the deposition pressure is 1kPa~4kPa, and the deposition time is 400h~500h. When densifying the silicon carbide matrix using a precursor pyrolysis method, polycarbosilane is used as the precursor in an argon atmosphere. The pyrolysis temperature is 1250℃~1400℃, and the single holding time is 1h~3h.

[0018] In a preferred embodiment of the present invention, the β-phase silicon carbide coating thickness is 50 μm to 150 μm. The chemical vapor deposition precursor gas source is trichloromethylsilane, the carrier gas is argon, and the dilution gas is hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane is 9 to 11:1. The flow rate of the carrier gas hydrogen is 1 L / min to 2 L / min, the flow rate of the dilution gas hydrogen is 1 L / min to 2 L / min, and the flow rate of the dilution gas argon is 3 L / min to 5 L / min. The deposition temperature is 1300℃ to 1400℃, the deposition pressure is 3 kPa to 5 kPa, and the deposition time is 20 h to 50 h.

[0019] In a preferred embodiment of the present invention, during ball milling, the ball-to-material mass ratio is 7-9:1, the ball milling time is 24 hours, and the ball milling speed is 450 r / min.

[0020] In a preferred embodiment of the present invention, the SiC prefabricated fabric is a two-dimensional woven SiC fiber fabric, and the multilayer SiC prefabricated fabric has 8 to 10 layers.

[0021] The second objective of this invention is to provide a SiC ceramic-based composite flow channel insert prepared by any of the above-described methods. The SiC ceramic-based composite flow channel insert structure includes a silicon carbide prefabricated cloth, on which a pyrolytic carbon interface with a thickness of 100 nm to 400 nm is deposited. The silicon carbide prefabricated cloth is coated with polycarbosilane, SiC, ZrO2, and Al2O3 particles. The entire structure is densified with a silicon carbide matrix, and after processing, a 50 μm to 150 μm β-SiC coating is obtained by high-temperature chemical vapor deposition. The preparation method of this invention can ensure that the functional particles of zirconium oxide and alumina are successfully introduced internally rather than externally, because the external structure must be maintained within the silicon carbide phase structure, thus ensuring its resistance to liquid lithium-lead circuit corrosion.

[0022] The third objective of this invention is to provide an application of the aforementioned SiC ceramic-based composite flow channel insert in the fusion reactor blanket structure.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention employs a chemical vapor infiltration process to deposit a pyrolytic carbon interface on a multilayer SiC prefabricated fabric, resulting in a SiC prefabricated fabric with a deposited pyrolytic carbon interface. SiC powder, ZrO2 powder, and Al2O3 powder are ball-milled and mixed. The mixed powder is then ground and sieved to obtain a filler powder mixture. This filler powder mixture is mixed with water, and polycarbosilane is added and stirred to obtain a slurry. The slurry is uniformly coated onto the SiC prefabricated fabric with the deposited pyrolytic carbon interface. The SiC prefabricated fabric coated with the slurry is then densified to obtain a SiC ceramic-based composite flow channel insert preform. Finally, after processing the SiC ceramic-based composite flow channel insert preform, a β-phase silicon carbide coating is prepared using high-temperature chemical vapor deposition to obtain the SiC ceramic-based composite flow channel insert. This invention introduces zirconia and alumina functional particles through a coating method. Finite element analysis revealed the thermal conductivity of the composite material, showing that the thermal conductivity of the ceramic-based composite flow channel insert is no higher than 5 W / m·K, indicating excellent thermal insulation and thermal conductivity. Good thermal insulation increases the average temperature of the liquid lithium-lead metal fluid at the outlet of the flow channel insert, thereby improving thermal efficiency. Simultaneously, it reduces the structural thermal stress of the first wall, ensuring structural safety. Furthermore, good thermal insulation helps maintain a stable flow field and reduces the additional resistance generated by the flowing liquid lithium-lead metal fluid, thus reducing the pressure drop of the magnetohydrodynamic fluid and improving energy conversion efficiency. Attached Figure Description

[0025] Figure 1 The flowchart shows the SiC ceramic-based composite flow channel insert prepared according to the present invention.

[0026] Figure 2 SiC prepared in Example 1 of this invention f / PyC-ZrO2-Al2O3-SiC composite flow channel plug, (a) longitudinal surface view of the flow channel plug, (b) cross-sectional view of the flow channel plug.

[0027] Figure 3 SiC prepared in Example 1 of this invention f Scanning electron micrographs of the PyC-ZrO2-Al2O3-SiC composite flow channel insert: (a) a cross-sectional scan of the flow channel insert with a resolution of 50 micrometers, the part within the dashed box is ZrO2 and Al2O3; (b) a cross-sectional scan of the flow channel insert with a resolution of 100 micrometers, the part within the dashed box is ZrO2 and Al2O3; (c) a surface scan of the flow channel insert with a resolution of 100 micrometers, the part within the dashed box is ZrO2 and Al2O3.

[0028] Figure 4 SiC prepared in Example 1 of this invention fThe relationship between thermal conductivity and the SiC / ZrO2 / Al2O3 ratio was obtained through finite element simulation calculations for the / PyC-ZrO2-Al2O3-SiC composite flow channel plug-in.

[0029] Figure 5 The SiC prepared in Example 1 of this invention f The surface of the PyC-ZrO2-Al2O3-SiC composite flow channel insert blank is coated with SiC using CVD process. Detailed Implementation

[0030] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0032] The flowchart of the SiC ceramic-based composite flow channel insert prepared by this invention is as follows: Figure 1 As shown, firstly, SiC prefabricated fabric is prepared, the size of the SiC prefabricated fabric is designed, and a specified number of SiC prefabricated fabrics are cut; then, a mixed slurry containing SiC, ZrO2, Al2O3, and PCS is prepared, and a PyC interface is deposited using the CVI process to obtain a SiC fiber prefabricated body with a PyC interface; then, the SiC matrix is ​​densified using chemical vapor infiltration deposition or precursor pyrolysis to obtain a composite flow channel insert blank; after processing and polishing the composite flow channel insert blank, a SiC coating is deposited using the CVD process to obtain a composite flow channel insert with high thermal insulation and electrical insulation properties.

[0033] Example 1

[0034] A SiC f The preparation method of the PyC-ZrO2-Al2O3-SiC composite flow channel plug includes the following steps:

[0035] (1) Cutting of SiC prefabricated fabric: Use a ruler to measure the size of 1020mm×600mm on the 2D SiC fiber fabric, cut it according to the size with a knife, a total of 9 pieces are cut, and then soak them in anhydrous ethanol for ultrasonic cleaning to remove surface impurities. After drying, they are aligned and stacked flat. Use graphite clamps to fix the arranged SiC fiber prefabricated fabric and fix it around the perimeter with graphite bolts to ensure the flatness of the SiC fiber fabric. Then, chemical vapor infiltration process is used to deposit pyrolytic carbon interface. The precursor gas source used for chemical vapor infiltration process is propylene, the diluent gas is argon, the deposition temperature is 900℃, the deposition pressure is 2kPa, and the deposition time is 100h to obtain SiC fiber fabric with pyrolytic carbon interface deposited.

[0036] (2) Preparation of mixed slurry: SiC powder, ZrO2 powder and Al2O3 powder were mixed in a volume ratio of 10:60:30. The mixed powder was then placed in a ball mill jar and ball milled for 24 hours at a ball-to-powder mass ratio of 7:1 and a ball milling speed of 450 r / min to form mixed powder. The uniformly mixed powder was then ground and sieved to obtain a filler powder mixture. The filler powder mixture and ultrapure water were placed in a beaker in a mass ratio of 4:1. Then, 55% of polycarbosilane was added to the filler powder mixture and mixed evenly using an electric stirrer at a speed of 200 rpm for 10 min to obtain a non-fluid coating slurry.

[0037] (3) Matrix densification: The slurry prepared in step (2) is uniformly coated with a brush onto the surface of the SiC fiber cloth with the pyrolytic carbon interface prepared in step (1). Then, the prefabricated cloth with multiple layers of slurry coating is stacked and fixed with a graphite clamp. Finally, the SiC matrix is ​​densified using a chemical vapor infiltration process. The precursor gas source used is trichloromethylsilane, the carrier gas is argon, and the diluent gas is hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 8.5:1. The flow rate of the carrier gas hydrogen is 1 L / min, the flow rate of the diluent gas hydrogen is 1 L / min, the flow rate of the diluent gas argon is 4 L / min, the deposition temperature is 950℃, the deposition pressure is 3 kPa, and the deposition time is 400 h. SiC is obtained. f / PyC-ZrO2-Al2O3-SiC composite flow channel insert rough blank.

[0038] (4) Deposition of SiC coating: After processing the rough blank prepared in step (3), a 50 μm silicon carbide coating is prepared by chemical vapor deposition. The precursor gas source is trichloromethylsilane, the carrier gas is argon, and the dilution gas is hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 9:1. The flow rate of the carrier gas hydrogen is 1 L / min, the flow rate of the dilution gas hydrogen is 1 L / min, and the flow rate of the dilution gas argon is 3 L / min. The deposition temperature is 1300℃, the deposition pressure is 3 kPa, and the deposition time is 20 h to obtain SiC. f The PyC-ZrO2-Al2O3-SiC composite flow channel insert was tested, and its density, measured using Archimedes' displacement method, was approximately 2.92 g / cm³. 3 .

[0039] Example 2

[0040] A SiC f The preparation method of the PyC-ZrO2-Al2O3-SiC composite flow channel plug includes the following steps:

[0041] (1) Cutting of SiC prefabricated fabric: Measure the size of the 2D SiC fiber fabric (1030mm×600mm) with a ruler, cut it according to the size with a knife, and cut a total of 10 pieces. Soak the pieces in anhydrous ethanol for ultrasonic cleaning to remove surface impurities. After drying, align and stack them flat. Fix the prepared SiC fiber prefabricated fabric with graphite clamps and fix it with graphite bolts around the edges to ensure the flatness of the SiC fiber fabric. Then, use chemical vapor infiltration (CVI) to deposit the pyrolytic carbon interface. The precursor gas source used for CVI deposition is propylene, the diluent gas is argon, the deposition temperature is 920℃, the deposition pressure is 4kPa, and the deposition time is 150h to obtain SiC fiber fabric with a pyrolytic carbon interface.

[0042] (2) Preparation of mixed slurry: SiC powder, ZrO2 powder and Al2O3 powder were mixed in a volume ratio of 10:70:20. The mixed powder was then placed in a ball mill jar and ball milled for 24 hours at a ball-to-powder mass ratio of 8:1 and a ball milling speed of 450 r / min to form mixed powder. The uniformly mixed powder was then ground and sieved to obtain a filler powder mixture. The filler powder mixture and ultrapure water were placed in a beaker in a mass ratio of 6:1. Then, 60% of the filler powder mixture by mass of polycarbosilane was added. The mixture was stirred evenly with an electric stirrer at a speed of 200 rpm for 10 min to obtain a non-fluid coating slurry.

[0043] (3) Matrix densification: The slurry prepared in step (2) is uniformly coated on the surface of the SiC fiber cloth with PyC interface prepared in step (1) by brush. Then, the prefabricated cloth with multiple layers of slurry is stacked and fixed with graphite clamps. Finally, the SiC matrix is ​​densified by precursor pyrolysis. The precursor gas source used is polycarbosilane, argon atmosphere, pyrolysis temperature is 1400℃, single heat preservation time is 3h, and SiCf / PyC-ZrO2-Al2O3-SiC composite flow channel insert blank is obtained.

[0044] (4) Deposition of SiC coating: After processing the rough blank prepared in step (3), a 150 μm silicon carbide coating is prepared by chemical vapor deposition. The precursor gas source is trichloromethylsilane, the carrier gas is argon, and the dilution gas is hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 11:1. The flow rate of the carrier gas hydrogen is 2 L / min, the flow rate of the dilution gas hydrogen is 2 L / min, and the flow rate of the dilution gas argon is 5 L / min. The deposition temperature is 1400℃, the deposition pressure is 5 kPa, and the deposition time is 50 h to obtain SiC. f The PyC-ZrO2-Al2O3-SiC composite flow channel insert was tested, and its density, measured using Archimedes' displacement method, was approximately 2.95 g / cm³. 3 .

[0045] Example 3

[0046] A SiC f The preparation method of the PyC-ZrO2-Al2O3-SiC composite flow channel plug includes the following steps:

[0047] (1) Cutting of SiC prefabricated fabric: Use a ruler to measure the size of 1020mm×600mm on the 2D SiC fiber fabric, and cut it according to the size with a knife. A total of 9 pieces were cut and ultrasonically cleaned by soaking in anhydrous ethanol to remove surface impurities. After drying, they were aligned and stacked flat. The prepared SiC fiber prefabricated fabric was fixed with graphite clamps and fixed around the perimeter with graphite bolts to ensure the flatness of the SiC fiber fabric. Then, a chemical vapor infiltration process was used to deposit the pyrolytic carbon interface. The precursor gas source used for chemical vapor infiltration deposition was propylene, the diluent gas was argon, the deposition temperature was 850℃, the deposition pressure was 5kPa, and the deposition time was 80h to obtain SiC fiber fabric with a pyrolytic carbon interface.

[0048] (2) Preparation of mixed slurry: SiC powder, ZrO2 powder and Al2O3 powder were mixed in a volume ratio of 10:80:10. The mixed powder was then placed in a ball mill jar and ball milled for 24 hours at a ball-to-powder mass ratio of 7:1 and a ball milling speed of 450 r / min to form mixed powder. The uniformly mixed powder was then ground and sieved to obtain a filler powder mixture. The filler powder mixture and ultrapure water were placed in a beaker in a mass ratio of 5:1. Then, 50% of the filler powder mixture by mass of polycarbosilane was added. The mixture was stirred evenly with an electric stirrer at a speed of 200 rpm for 10 min to obtain a non-fluid coating slurry.

[0049] (3) Matrix densification: The slurry prepared in step (2) is uniformly coated with a brush onto the surface of the SiC fiber cloth with the pyrolytic carbon interface prepared in step (1). Then, the prefabricated cloth with multiple layers of slurry coating is stacked and fixed with a graphite clamp. Finally, the SiC matrix is ​​densified using a chemical vapor infiltration process. The precursor gas source used is trichloromethylsilane, the carrier gas is argon, and the diluent gas is hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 10:1. The flow rate of the carrier gas hydrogen is 3 L / min, the flow rate of the diluent gas hydrogen is 2 L / min, and the flow rate of the diluent gas argon is 3 L / min. The deposition temperature is 900℃, the deposition pressure is 1 kPa, and the deposition time is 500 h to obtain SiC. f / PyC-ZrO2-Al2O3-SiC composite flow channel insert rough blank.

[0050] (4) Deposition of SiC coating: After processing the rough blank prepared in step (3), a 50 μm silicon carbide coating is prepared by chemical vapor deposition. The precursor gas source is trichloromethylsilane, the carrier gas is argon, and the dilution gas is hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 10:1. The flow rate of the carrier gas hydrogen is 1.5 L / min, the flow rate of the dilution gas hydrogen is 1.5 L / min, and the flow rate of the dilution gas argon is 4 L / min. The deposition temperature is 1400℃, the deposition pressure is 5 kPa, and the deposition time is 30 h to obtain SiC. f The PyC-ZrO2-Al2O3-SiC composite flow channel insert was tested, and its density, measured using Archimedes' displacement method, was approximately 2.98 g / cm³. 3 .

[0051] Results Analysis

[0052] In Example 1, the SiCf / PyC-ZrO2-Al2O3-SiC composite flow channel insert prepared by coating method is as follows: Figure 2As shown, (a) is a longitudinal surface view of the flow channel insert, and (b) is a cross-sectional view of the flow channel insert. It can be seen that the prepared flow channel insert has a height of 1020 mm, a width of 100 mm, and a wall thickness of 5 mm. The results indicate that a large-size silicon carbide-based composite flow channel insert with uniform wall thickness was successfully prepared by coating method and substrate densification process.

[0053] Figure 3 SiC prepared in Example 1 of this invention f Scanning electron micrographs of the PyC-ZrO2-Al2O3-SiC composite flow channel insert: (a) a cross-sectional scan of the flow channel insert with a resolution of 50 μm, where the part within the dashed box represents ZrO2 and Al2O3 particles; (b) a cross-sectional scan of the flow channel insert with a resolution of 100 μm, where the part within the dashed box represents ZrO2 and Al2O3 particles; and (c) a surface scan of the flow channel insert with a resolution of 100 μm, where the part within the dashed box represents ZrO2 and Al2O3 particles. The results indicate that functional components such as zirconium oxide and alumina were successfully introduced into the interior of the composite flow channel insert, and that zirconium oxide and alumina are mainly distributed in the interlayer gaps of the fibers.

[0054] Figure 4 SiC prepared in Example 1 of this invention f The relationship between the thermal conductivity of the PyC-ZrO2-Al2O3-SiC composite flow channel plug and the SiC / ZrO2 / Al2O3 ratio was obtained through finite element simulation. This invention introduces zirconia and alumina functional particles through a coating method, and the thermal conductivity of the composite material was obtained through finite element simulation. It shows that the thermal conductivity of the ceramic-based composite flow channel plug is no higher than 5 W / m·K. The thermal conductivity of the composite material decreases with the increase of the proportion of functional particles, indicating that it has excellent thermal insulation and insulating properties.

[0055] Figure 5 The SiC prepared in Example 1 of this invention f The SiC coating deposited on the surface of the PyC-ZrO2-Al2O3-SiC composite flow channel insert using CVD process shows that the coating is tightly bonded to the substrate and has a thickness of about 76 μm. The results indicate that the composite flow channel insert prepared in this invention can obtain a uniform and dense silicon carbide coating through high-temperature chemical vapor deposition.

[0056] In summary, this invention introduces zirconia and alumina functional particles through a coating method. Finite element analysis revealed the thermal conductivity of the composite material, showing that the thermal conductivity of the ceramic-based composite flow channel insert is no higher than 5 W / m·K, indicating excellent thermal insulation and thermal conductivity. Good thermal insulation increases the average temperature of the liquid lithium-lead metal fluid at the outlet of the flow channel insert, thereby improving thermal efficiency. Simultaneously, it reduces the structural thermal stress of the first wall, ensuring structural safety. Furthermore, good thermal insulation helps maintain a stable flow field and reduces the additional resistance generated by the flowing liquid lithium-lead metal fluid, thus reducing the pressure drop of the magnetohydrodynamic fluid and improving energy conversion efficiency.

[0057] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0058] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a SiC ceramic-based composite flow channel insert, characterized in that, Includes the following steps: A pyrolytic carbon interface was deposited on a multilayer SiC prefabricated fabric using a chemical vapor infiltration process to obtain a SiC prefabricated fabric with a pyrolytic carbon interface deposited on it. SiC powder, ZrO2 powder, and Al2O3 powder are ball-milled and mixed. The resulting powder is then ground and sieved to obtain a filler powder mixture. This filler powder mixture is mixed with water, and then polycarbosilane is added and stirred to obtain a slurry. The volume ratio of SiC powder, ZrO2 powder, and Al2O3 powder is 10:60~80:10~30, the mass ratio of the filler powder mixture to water is 4~6:1, and the mass fraction of polycarbosilane in the filler powder mixture is 50%~60%. The mixed slurry is uniformly coated onto a SiC prefabricated fabric with a pyrolytic carbon interface, and then the SiC prefabricated fabric coated with the mixed slurry is densified to deposit a silicon carbide substrate to obtain a SiC ceramic-based composite flow channel insert blank. After processing the SiC ceramic-based composite flow channel insert blank, a β-phase silicon carbide coating is prepared by high-temperature chemical vapor deposition to obtain the SiC ceramic-based composite flow channel insert.

2. The method for preparing SiC ceramic-based composite flow channel inserts according to claim 1, characterized in that, The deposition thickness of the pyrolytic carbon interface is 100 nm to 400 nm. During the deposition of the pyrolytic carbon interface, the precursor gas source is propylene, the diluent gas is argon, the deposition temperature is 850 °C to 950 °C, the deposition pressure is 2 kPa to 5 kPa, and the deposition time is 80 h to 250 h.

3. The method for preparing the SiC ceramic-based composite flow channel insert according to claim 1, characterized in that, The densification process is a chemical vapor infiltration process or a precursor pyrolysis method. After densification, the porosity of the silicon carbide matrix is ​​5% to 15%.

4. The method for preparing the SiC ceramic-based composite flow channel insert according to claim 3, characterized in that, When densifying silicon carbide substrates using chemical vapor infiltration, the precursor gas source is trichloromethylsilane, the carrier gas is argon, and the diluent gases are hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 8.5~10:1, the deposition temperature is 900℃~1100℃, the deposition pressure is 1kPa~4kPa, and the deposition time is 400h~500h. When densifying silicon carbide substrates using precursor pyrolysis, polycarbosilane is used as the precursor in an argon atmosphere. The pyrolysis temperature is 1250℃~1400℃, and the single holding time is 1h~3h.

5. The method for preparing SiC ceramic-based composite flow channel inserts according to claim 1, characterized in that, The thickness of the β-phase silicon carbide coating is 50 μm to 150 μm. The precursor gas source for chemical vapor deposition is trichloromethylsilane, the carrier gas is argon, and the dilution gas is hydrogen and argon. The molar ratio of hydrogen to trichloromethylsilane is 9 to 11:

1. The deposition temperature is 1300℃ to 1400℃, the deposition pressure is 3 kPa to 5 kPa, and the deposition time is 20 h to 50 h.

6. The method for preparing the SiC ceramic-based composite flow channel insert according to claim 1, characterized in that, The SiC prefabricated fabric is a two-dimensional woven SiC fiber fabric, and the multilayer SiC prefabricated fabric has 8 to 10 layers.

7. A SiC ceramic-based composite flow channel insert prepared by the method according to any one of claims 1-6, characterized in that, The SiC ceramic-based composite flow channel insert structure includes a silicon carbide prefabricated cloth, on which a pyrolytic carbon interface with a thickness of 100nm~400nm is deposited. The silicon carbide prefabricated cloth is coated with polycarbosilane, SiC, ZrO2 and Al2O3 particles. The entire structure is densified with silicon carbide matrix, and after processing, a 50μm~150μm β-SiC coating is obtained by high temperature chemical vapor deposition process.

8. The SiC ceramic-based composite flow channel insert according to claim 7, characterized in that, The density of the SiC ceramic-based composite flow channel insert is ≥2.85 g / cm³. 3 Thermal conductivity ≤ 5 W / m·K.

9. The application of the SiC ceramic-based composite flow channel insert as described in claim 7 in the fusion reactor blanket structure.

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