SiC ceramic-based composite runner insert as well as preparation method and application thereof

Abstract

The invention relates to the technical field of runner inserts in fusion reactor cladding structures, in particular to a SiC ceramic-based composite runner insert and a preparation method and application thereof.The preparation method includes the steps that a pyrolytic carbon interface is deposited on SiC prefabricated cloth, and the SiC prefabricated cloth deposited with the pyrolytic carbon interface is obtained; the preparation method comprises the following steps: 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 mixed slurry; the mixed slurry is coated on SiC prefabricated cloth, a SiC prefabricated cloth deposition silicon carbide substrate is subjected to densification treatment and finish machining, then a silicon carbide coating is prepared through chemical vapor deposition, and the SiC ceramic-based composite flow channel plug-in is obtained. The preparation method aims at further enhancing the heat insulation performance and the insulating performance of the SiC ceramic-based composite flow channel plug-in, improving the heat insulation performance of the SiC ceramic-based composite flow channel plug-in and improving the heat insulation performance of the SiC ceramic-based composite flow channel plug-in. The average temperature at the outlet of the runner insert is increased, the pressure drop of the magnetofluid is reduced, high-efficiency energy conversion is realized, and meanwhile, long-term safe operation of a reactor is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of flow channel plug-ins in fusion reactor blanket structures, and in particular to a SiC ceramic-based composite flow channel plug-in and a preparation method and application thereof. Background Art

[0002] The blanket system structure that can achieve fusion energy resistance usually consists of four parts: steel wall, gas gap flow area, flow channel plug and central metal mainstream area. The outer steel wall of the blanket system directly faces the extremely high temperature center of the reactor. The gas gap flow area is the boundary condition for convective heat transfer through inert gas. The metal fluid in the inner layer is mainly responsible for heat exchange, and the flow channel plug is a component nested in the flow channel, which separates the fluid into two channels and provides thermal and electrical insulation in the blanket system.

[0003] In the blanket system, an efficient thermal management system ensures the safety and stable operation of the reactor, and the thermal insulation of the flow channel plug becomes a key factor. Good thermal insulation performance can prevent the heat from the high-temperature plasma area to other parts of the reactor to the greatest extent possible, prevent the degradation of material performance, structural deformation and even catastrophic failure caused by local overheating, and ensure the integrity of the overall structure of the reactor. At the same time, it helps to maintain the high-temperature environment of the plasma, reduce unnecessary heat loss, improve energy utilization efficiency, and enable the fusion reaction to proceed continuously and stably.

[0004] In addition, since the fusion reaction occurs in a strong magnetic field environment and the liquid lithium-lead metal flows at high speed in the flow channel, electromagnetic induction is inevitable. If the flow channel plug lacks sufficient insulation, the conductive particles in the coolant will easily generate induced current under the action of the magnetic field, and then suffer from strong electromagnetic interference, which will not only disrupt the normal flow of the coolant, greatly increase the flow resistance, cause an increase in pressure drop, and affect the efficiency of the cooling system, but may also trigger electrochemical reactions, corrode the flow channel plug and the components connected to it, and reduce the reliability and service life of the entire system. Therefore, ensuring that the flow channel plug has excellent insulation performance is a necessary condition for shielding electromagnetic interference, maintaining stable coolant flow, and ensuring the long-term safe operation of the reactor.

[0005] The materials currently used for flow channel plugs are generally SiC ceramic-based composite materials with high thermal stability. However, with the development of fusion reactors, higher requirements are placed on the performance of SiC ceramic-based composite materials. It is necessary to further improve the thermal insulation and insulating properties of existing SiC ceramic composite flow channel plugs. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a SiC ceramic-based composite flow channel plug and a preparation method and application thereof. The present invention aims to further enhance the thermal insulation and insulating properties of the SiC ceramic-based composite flow channel plug, increase the average temperature at the outlet of the flow channel plug, reduce the pressure drop of the magnetic fluid, achieve high-efficiency energy conversion, and ensure the long-term safe operation of the reactor.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for preparing a SiC ceramic-based composite flow channel plug comprises the following steps: The chemical vapor infiltration process is used to deposit a pyrolytic carbon interface on the multi-layer SiC preform to obtain a SiC preform with a pyrolytic carbon interface, which can effectively protect the silicon carbide fiber and improve its strength and toughness. Compared with chemical vapor deposition or other processes, the chemical vapor infiltration process can uniformly deposit pyrolytic carbon in complex shapes and porous structures, effectively improve the mechanical properties and thermal shock resistance of the composite material, and is suitable for the complex structure of the fiber preform.

[0008] The SiC powder and the functional particles with low thermal conductivity and radiation resistance are ball-milled and mixed, wherein the functional particles with low thermal conductivity and radiation resistance are ZrO 2 Powder and Al 2 O 3 The mixed powder is ground and sieved to obtain a filler powder mixture, the filler powder mixture is mixed with water, and polycarbosilane is added and stirred to obtain a mixed slurry, wherein alumina and zirconia have good chemical stability at high temperatures, can effectively reduce the thermal conductivity of the SiC matrix, thereby improving the thermal insulation capacity of the composite material, while zirconia has low thermal conductivity and high thermal expansion coefficient, can relieve thermal stress and reduce thermal shock damage, in addition, the thermal expansion coefficient of alumina is close to that of SiC, which helps to reduce interface thermal stress and further improve thermal shock resistance.

[0009] The mixed slurry is evenly coated on the SiC prefabricated cloth with the pyrolytic carbon interface deposited thereon, and then the SiC prefabricated cloth coated with the mixed slurry and the deposited silicon carbide matrix are densified to obtain a rough blank of a SiC ceramic-based composite flow channel plug.

[0010] After the rough SiC ceramic-based composite flow channel plug-in is processed, a β-phase silicon carbide coating is prepared by high-temperature chemical vapor deposition to obtain a SiC ceramic-based composite flow channel plug-in.

[0011] The present invention introduces zirconium oxide and aluminum oxide functional particles by coating method, and obtains the thermal conductivity of the composite material by finite element simulation, indicating that the present invention makes the thermal conductivity of the ceramic-based composite flow channel plug not higher than 5W / m·K, indicating that it has excellent thermal insulation and insulating properties. Good thermal insulation can increase the average temperature of the liquid lithium-lead metal fluid at the outlet of the flow channel plug, thereby improving thermal efficiency, while reducing the structural thermal stress of the first wall, thereby ensuring its structural safety. In addition, good insulation performance helps maintain a stable flow field, while reducing the additional resistance generated by the flowing liquid lithium-lead metal fluid, thereby reducing the pressure drop of the magnetic fluid and improving the energy conversion rate.

[0012] In a preferred embodiment of the present invention, SiC powder, ZrO 2 Powder and Al 2 O 3 The volume ratio of the 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%.

[0013] In a preferred embodiment of the present invention, the deposition thickness of the pyrolytic carbon interface is 100nm~400nm. When depositing the pyrolytic carbon interface, the precursor gas source is propylene, the dilution gas is argon, the deposition temperature is 850℃~950℃, the deposition pressure is 2kPa~5kPa, and the deposition time is 80h~250h.

[0014] In a preferred embodiment of the present invention, the densification treatment method is a chemical vapor infiltration process or a precursor cracking method, and the porosity of the silicon carbide matrix after the densification treatment is 5% to 15%.

[0015] In a preferred embodiment of the present invention, when chemical vapor infiltration is used to densify the silicon carbide matrix, the precursor gas source is trichloromethylsilane, the carrier gas is argon, and the diluent gas is hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane is 8.5~10:1, the carrier gas hydrogen flow rate is 1L / min~L / min, the diluent gas hydrogen flow rate is 1L / min~2L / min, and the diluent gas 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 the precursor pyrolysis method is used to densify the silicon carbide matrix, the precursor uses polycarbosilane, argon atmosphere, the pyrolysis temperature is 1250℃~1400℃, and the single insulation time is 1h~3h.

[0016] In a preferred embodiment of the present invention, the deposition thickness of the β-phase silicon carbide coating is 50 μm to 150 μm, the chemical vapor deposition precursor gas source is trichloromethylsilane, the carrier gas is argon, and the diluent gas is hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane is 9 to 11:1, the carrier gas hydrogen flow rate is 1 L / min to 2 L / min, the diluent gas hydrogen flow rate is 1 L / min to 2 L / min, and the diluent gas argon flow rate is 3 L / min to 5 L / min. The deposition temperature is 1300°C to 1400°C, the deposition pressure is 3 kPa to 5 kPa, and the deposition time is 20 h to 50 h.

[0017] 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.

[0018] In a preferred embodiment of the present invention, the SiC prefabricated fabric is a SiC fiber fabric with a two-dimensional woven structure, and the multi-layer SiC prefabricated fabric has 8 to 10 layers.

[0019] The second object of the present invention is to provide a SiC ceramic-based composite flow channel plug prepared by any of the preparation methods described above, wherein the SiC ceramic-based composite flow channel plug structure comprises a silicon carbide prefabricated cloth, a pyrolytic carbon interface with a thickness of 100nm to 400nm is deposited on the silicon carbide prefabricated cloth, and polycarbosilane, SiC, ZrO are coated on the silicon carbide prefabricated cloth. 2 and Al 2 O 3 The particles, the whole structure is densified by the silicon carbide matrix, and after processing, a 50μm~150μm β-SiC coating is obtained by a high-temperature chemical vapor deposition process. The preparation method of the present invention can ensure that the zirconium oxide and aluminum oxide functional particles are successfully introduced inside rather than outside, because the outside must be guaranteed to be in the silicon carbide phase structure, so that it can ensure its resistance to liquid lithium-lead circuit corrosion.

[0020] The third object of the present invention is to provide an application of the above-mentioned SiC ceramic-based composite flow channel plug in a fusion reactor blanket structure.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a chemical vapor infiltration process to deposit a pyrolytic carbon interface on a multi-layer SiC prefabricated fabric to obtain a SiC prefabricated fabric with a pyrolytic carbon interface deposited thereon; SiC powder, ZrO 2 Powder and Al 2 O 3The powder is ball-milled and mixed, and the mixed powder is ground and sieved to obtain a filler powder mixture, and the filler powder mixture is mixed with water, and then polycarbosilane is added and stirred to obtain a mixed slurry; the mixed slurry is evenly coated on a SiC prefabricated cloth deposited with a pyrolytic carbon interface, and then the SiC prefabricated cloth coated with the mixed slurry is subjected to a densification treatment to obtain a SiC ceramic-based composite flow channel plug-in rough blank; finally, the SiC ceramic-based composite flow channel plug-in rough blank is processed, and a β-phase silicon carbide coating is prepared by high-temperature chemical vapor deposition to obtain a SiC ceramic-based composite flow channel plug-in. The present invention introduces zirconium oxide and aluminum oxide functional particles by coating method, and obtains the thermal conductivity of the composite material by finite element simulation, indicating that the present invention makes the thermal conductivity of the ceramic-based composite flow channel plug-in not higher than 5W / m·K, indicating that it has excellent thermal insulation and insulating properties. Good thermal insulation can increase the average temperature of the liquid lithium-lead metal fluid at the outlet of the flow channel plug, thereby improving thermal efficiency, while reducing the structural thermal stress of the first wall, thereby ensuring its structural safety. In addition, good insulation performance helps to maintain a stable flow field, while reducing the additional resistance generated by the flowing liquid lithium-lead metal fluid, thereby reducing the pressure drop of the magnetic fluid and improving the energy conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a flow chart of the SiC ceramic matrix composite flow channel plug prepared by the present invention.

[0023] Figure 2 SiC prepared in Example 1 of the present invention f / PyC-ZrO 2 -Al 2 O 3 -SiC composite runner insert, (a) longitudinal surface view of the runner insert, (b) cross-sectional view of the runner insert.

[0024] Figure 3 SiC prepared in Example 1 of the present invention f / PyC-ZrO 2 -Al 2 O 3 -Scanning electron micrograph of SiC composite flow channel plug, (a) Scanning image of the cross section of the flow channel plug with a resolution of 50 μm, the part within the dashed box is ZrO 2 、Al 2 O 3 , (b) Scanning image of the cross section of the flow channel plug with a resolution of 100 μm. The part within the dashed box is ZrO 2 、Al 2 O 3 , (c) Scanning image of the flow channel plug surface with a resolution of 100 μm. The part within the dotted box is ZrO 2 、Al2 O 3 .

[0025] Figure 4 SiC prepared in Example 1 of the present invention f / PyC-ZrO 2 -Al 2 O 3 -SiC composite flow channel plug-in thermal conductivity calculated by finite element simulation and SiC / ZrO 2 / Al 2 O 3 The relationship between the ratios.

[0026] Figure 5 The SiC prepared in Example 1 of the present invention f / PyC-ZrO 2 -Al 2 O 3 -The SiC composite flow channel plug rough surface is coated with SiC by CVD process. DETAILED DESCRIPTION

[0027] The following is a detailed description of the technical solutions in the embodiments of the present invention in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0029] The flow chart of the SiC ceramic matrix composite flow channel plug prepared by the present invention is as follows Figure 1 As shown, first, prepare the SiC prefabricated fabric, design the size of the SiC prefabricated fabric and cut a specified number of SiC prefabricated fabrics; then prepare a SiC, ZrO 2 and Al 2 O 3 and PCS mixed slurry, using CVI process to deposit PyC interface to obtain SiC fiber preform with PyC interface; then using chemical vapor infiltration deposition or precursor cracking method to densify the SiC matrix to obtain a composite flow channel plug-in rough blank; after processing and polishing the composite flow channel plug-in rough blank, using CVD process to deposit SiC coating to obtain a composite flow channel plug-in with high thermal insulation and insulation.

[0030] Example 1 A SiC f / PyC-ZrO 2 -Al 2 O 3 -A method for preparing a SiC composite flow channel insert comprises the following steps: (1) Cutting of SiC prefabricated cloth: Use a ruler to measure the size of 1020 mm × 600 mm on the 2D SiC fiber cloth, and use a knife to cut it according to the size. A total of 9 sheets are cut, and they are soaked in anhydrous ethanol for ultrasonic cleaning. After removing surface impurities and drying, they are aligned and stacked. Use a graphite splint to fix the arranged SiC fiber prefabricated cloth, and fix it around with graphite bolts to ensure the flatness of the SiC fiber cloth. Then, chemical vapor infiltration process is used to deposit pyrolytic carbon interface. The precursor gas source used for chemical vapor infiltration deposition is propylene, the diluent gas is argon, the deposition temperature is 900 ° C, the deposition pressure is 2 kPa, and the deposition time is 100 h. SiC fiber cloth with pyrolytic carbon interface is obtained.

[0031] (2) Preparation of mixed slurry: SiC powder, ZrO 2 Powder and Al 2 O 3 After the powders are mixed in a volume fraction ratio of 10:60:30, the mixed powders are placed in a ball mill and ball milled for 24 hours at a ball-to-material mass ratio of 7:1 at a ball mill speed of 450 r / min to form a mixed powder. Subsequently, the evenly mixed powders are ground and sieved to obtain a filler powder mixture. The filler powder mixture and ultrapure water are placed in a beaker at a mass ratio of 4:1, and then 55% polycarbosilane by mass fraction of the filler powder mixture is added. The mixture is mixed evenly with an electric stirrer at a speed of 200 rmp and a stirring time of 10 min to obtain a coating slurry in a non-fluid state.

[0032] (3) Densification of the matrix: The slurry prepared in step (2) is evenly coated on the surface of the SiC fiber cloth deposited with the pyrolytic carbon interface prepared in step (1) with a brush, and then the prefabricated cloth with multiple layers of slurry is stacked and fixed with a graphite clamp, and finally the SiC matrix is ​​densified by chemical vapor infiltration process, the precursor gas source used is trichloromethylsilane, the carrier gas is argon, and the diluent gas is hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane is 8.5:1, the carrier gas hydrogen flow rate is 1L / min, the diluent gas hydrogen flow rate is 1L / min, the diluent gas argon flow rate is 4L / min, the deposition temperature is 950°C, the deposition pressure is 3kPa, and the deposition time is 400h, to obtain SiC f / PyC-ZrO 2-Al 2 O 3 -SiC composite flow channel insert rough blank.

[0033] (4) Deposition of SiC coating: After the rough blank prepared in step (3) was processed, a 50 μm silicon carbide coating was prepared by chemical vapor deposition, the precursor gas source was trichloromethylsilane, the carrier gas was argon, the diluent gas was hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane was 9:1, the carrier gas hydrogen flow rate was 1 L / min, the diluent gas hydrogen flow rate was 1 L / min, the diluent gas argon flow rate was 3 L / min, the deposition temperature was 1300°C, the deposition pressure was 3 kPa, and the deposition time was 20 h, to obtain SiC f / PyC-ZrO 2 -Al 2 O 3 -SiC composite flow channel plug, and the density of the plug measured by Archimedes drainage method is about 2.92g / cm 3 .

[0034] Example 2 A SiC f / PyC-ZrO 2 -Al 2 O 3 -A method for preparing a SiC composite flow channel insert comprises the following steps: (1) Cutting of SiC prefabricated cloth: Use a ruler to measure the size of 1030mm×600mm on the 2D SiC fiber cloth, and use a knife to cut it according to the size. A total of 10 sheets are cut, and they are soaked in anhydrous ethanol for ultrasonic cleaning. After removing surface impurities and drying, they are aligned and stacked. Use a graphite splint to fix the arranged SiC fiber prefabricated cloth, and fix it around with graphite bolts to ensure the flatness of the SiC fiber cloth; then use the chemical vapor infiltration process to deposit the pyrolytic carbon interface. The precursor gas source used for the chemical vapor infiltration process 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 cloth with a pyrolytic carbon interface.

[0035] (2) Preparation of mixed slurry: SiC powder, ZrO 2 Powder and Al 2 O 3After the powders are mixed in a volume fraction ratio of 10:70:20, the mixed powders are placed in a ball mill and ball milled for 24 hours at a ball-to-material mass ratio of 8:1. The ball mill speed is 450 r / min to form a mixed powder. Then, the evenly mixed powders are ground and sieved to obtain a filler powder mixture. The filler powder mixture and ultrapure water are placed in a beaker in a mass ratio of 6:1, and then 60% polycarbosilane by mass fraction of the filler powder mixture is added. The mixture is mixed evenly with an electric stirrer at a speed of 200 rmp and a stirring time of 10 min to obtain a coating slurry in a non-fluid state.

[0036] (3) Densification of the matrix: The slurry prepared in step (2) is evenly coated on the surface of the SiC fiber cloth with the PyC interface deposited in step (1) with a brush, and then the prefabricated cloths with multiple layers of slurry coating are stacked and fixed with a graphite clamp. Finally, the SiC matrix is ​​densified by the precursor pyrolysis method. The precursor gas source used is polycarbosilane, argon atmosphere, pyrolysis temperature is 1400 ° C, and the single holding time is 3 h to obtain SiCf / PyC-ZrO 2 -Al 2 O 3 -SiC composite flow channel insert rough blank.

[0037] (4) Deposition of SiC coating: After the rough blank prepared in step (3) was processed, a 150 μm silicon carbide coating was prepared by chemical vapor deposition, wherein the precursor gas source was trichloromethylsilane, the carrier gas was argon, and the diluent gas was hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane was 11:1, the carrier gas hydrogen flow rate was 2 L / min, the diluent gas hydrogen flow rate was 2 L / min, the diluent gas argon flow rate was 5 L / min, the deposition temperature was 1400°C, the deposition pressure was 5 kPa, and the deposition time was 50 h, to obtain SiC f / PyC-ZrO 2 -Al 2 O 3 -SiC composite flow channel plug, and the density of the plug measured by Archimedes drainage method is about 2.95g / cm 3 .

[0038] Example 3 A SiC f / PyC-ZrO 2 -Al 2 O 3 -A method for preparing a SiC composite flow channel insert comprises the following steps: (1) Cutting of SiC prefabricated cloth: Use a ruler to measure the size of 1020 mm × 600 mm on the 2D SiC fiber cloth, and use a knife to cut it according to the size. A total of 9 sheets are cut, and they are soaked in anhydrous ethanol for ultrasonic cleaning. After removing surface impurities and drying, they are aligned and stacked flat; Use a graphite splint to fix the arranged SiC fiber prefabricated cloth, and fix it around with graphite bolts to ensure the flatness of the SiC fiber cloth, and then use chemical vapor infiltration technology to deposit pyrolytic carbon interface. The precursor gas source used for chemical vapor infiltration deposition is propylene, the diluent gas is argon, the deposition temperature is 850 ° C, the deposition pressure is 5 kPa, and the deposition time is 80 h, to obtain SiC fiber cloth with pyrolytic carbon interface deposited.

[0039] (2) Preparation of mixed slurry: SiC powder, ZrO 2 Powder and Al 2 O 3 After the powders are mixed in a volume fraction ratio of 10:80:10, the mixed powders are placed in a ball mill and ball milled for 24 hours at a ball-to-material mass ratio of 7:1 at a ball mill speed of 450 r / min to form a mixed powder. Subsequently, the evenly mixed powders are ground and sieved to obtain a filler powder mixture. The filler powder mixture and ultrapure water are placed in a beaker at a mass ratio of 5:1, and then 50% polycarbosilane by mass fraction of the filler powder mixture is added. The mixture is mixed evenly using an electric stirrer at a speed of 200 rmp and a stirring time of 10 min to obtain a coating slurry in a non-fluid state.

[0040] (3) Densification of the matrix: The slurry prepared in step (2) is evenly coated on the surface of the SiC fiber cloth deposited with the pyrolytic carbon interface prepared in step (1) with a brush, and then the prefabricated cloth with multiple layers of slurry coating is stacked and fixed with a graphite clamp, and finally the SiC matrix is ​​densified by chemical vapor infiltration process, the precursor gas source used is trichloromethylsilane, the carrier gas is argon, and the diluent gas is hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane is 10:1, the carrier gas hydrogen flow rate is 3L / min, the diluent gas hydrogen flow rate is 2L / min, the diluent gas argon flow rate is 3L / min, the deposition temperature is 900°C, the deposition pressure is 1kPa, and the deposition time is 500h, to obtain SiC f / PyC-ZrO 2 -Al 2 O 3 -SiC composite flow channel insert rough blank.

[0041] (4) Deposition of SiC coating: After the rough blank prepared in step (3) was processed, a 50 μm silicon carbide coating was prepared by chemical vapor deposition, wherein the precursor gas source was trichloromethylsilane, the carrier gas was argon, and the diluent gas was hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane was 10:1, the carrier gas hydrogen flow rate was 1.5 L / min, the diluent gas hydrogen flow rate was 1.5 L / min, the diluent gas argon flow rate was 4 L / min, the deposition temperature was 1400°C, the deposition pressure was 5 kPa, and the deposition time was 30 h, to obtain SiC f / PyC-ZrO 2 -Al 2 O 3 -SiC composite flow channel plug, and the density of the plug measured by Archimedes drainage method is about 2.98g / cm 3 .

[0042] Results Analysis In Example 1, SiCf / PyC-ZrO prepared by coating method 2 -Al 2 O 3 -SiC composite flow channel inserts such as Figure 2 As shown, (a) is the longitudinal surface view of the flow channel plug, and (b) is the cross-sectional view of the flow channel plug. It can be seen that the prepared flow channel plug is 1020mm high, 100mm wide, and 5mm thick. The results show that a large-sized silicon carbide-based composite flow channel plug with uniform wall thickness was successfully prepared by coating method and matrix densification process.

[0043] Figure 3 SiC prepared in Example 1 of the present invention f / PyC-ZrO 2 -Al 2 O 3 -Scanning electron micrograph of SiC composite flow channel plug, (a) Scanning image of the cross section of the flow channel plug with a resolution of 50 μm, the part within the dashed box is ZrO 2 and Al 2 O 3 Particles, (b) Scanning image of the cross section of the flow channel plug with a resolution of 100 μm. The part within the dashed box is ZrO 2 and Al 2 O 3 Particles, (c) Scanning image of the flow channel plug surface with a resolution of 100 μm, the part within the dotted box is ZrO 2 and Al 2 O 3 The results show that functional components such as zirconium oxide and aluminum oxide are successfully introduced into the composite flow channel plug-in, and zirconium oxide and aluminum oxide are mainly distributed in the gaps between fiber layers.

[0044] Figure 4 SiC prepared in Example 1 of the present invention f / PyC-ZrO 2 -Al 2 O 3 -SiC composite flow channel plug-in thermal conductivity calculated by finite element simulation and SiC / ZrO 2 / Al 2 O 3 The relationship between the ratios is shown in Figure 2. The present invention introduces zirconium oxide and aluminum oxide functional particles by a coating method, and obtains the thermal conductivity of the composite material by finite element simulation, which shows that the present invention makes the thermal conductivity of the ceramic-based composite flow channel plug-in not higher than 5W / m·K, and 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.

[0045] Figure 5 The SiC prepared in Example 1 of the present invention f / PyC-ZrO 2 -Al 2 O 3 -The SiC coating is deposited on the rough surface of the SiC composite flow channel plug by CVD process. It can be seen that the coating is tightly bonded to the substrate and has a thickness of about 76μm. The results show that the composite flow channel plug prepared by the present invention can obtain a uniform and dense silicon carbide coating by high-temperature chemical vapor deposition.

[0046] In summary, the present invention introduces zirconium oxide and aluminum oxide functional particles by coating method, and obtains the thermal conductivity of the composite material by finite element simulation, indicating that the present invention makes the thermal conductivity of the ceramic-based composite flow channel plug not higher than 5W / m·K, indicating that it has excellent thermal insulation and insulating properties. Good thermal insulation can increase the average temperature of the liquid lithium-lead metal fluid at the outlet of the flow channel plug, thereby improving thermal efficiency, while reducing the structural thermal stress of the first wall, thereby ensuring its structural safety. In addition, good insulation performance helps maintain a stable flow field, while reducing the additional resistance generated by the flowing liquid lithium-lead metal fluid, thereby reducing the pressure drop of the magnetic fluid and improving the energy conversion rate.

[0047] It should be noted that when the present invention involves a numerical range, it should be understood that the two 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 those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0048] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a SiC ceramic-based composite flow channel plug, characterized in that: The following steps are involved: A pyrolytic carbon interface is deposited on a multi-layer SiC prefabricated fabric by using a chemical vapor infiltration process to obtain a SiC prefabricated fabric with a pyrolytic carbon interface deposited thereon; Mixing SiC powder, ZrO2 powder and Al2O3 powder by ball milling, grinding the mixed powder, sieving to obtain a filler powder mixture, mixing the filler powder mixture with water, adding polycarbosilane, stirring to obtain a mixed slurry; The mixed slurry is evenly coated on the SiC prefabricated cloth with the pyrolytic carbon interface deposited thereon, and then the SiC prefabricated cloth coated with the mixed slurry and the deposited silicon carbide substrate is subjected to a densification treatment to obtain a rough blank of a SiC ceramic-based composite flow channel plug; After the rough SiC ceramic-based composite flow channel plug-in is processed, a β-phase silicon carbide coating is prepared by high-temperature chemical vapor deposition to obtain a SiC ceramic-based composite flow channel plug-in.

2. The method for preparing the SiC ceramic-based composite flow channel plug according to claim 1, characterized in that: 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%.

3. The method for preparing the SiC ceramic-based composite flow channel plug according to claim 1, characterized in that: The deposition thickness of the pyrolytic carbon interface is 100nm~400nm. When depositing the pyrolytic carbon interface, the precursor gas source is propylene, the dilution gas is argon, the deposition temperature is 850℃~950℃, the deposition pressure is 2kPa~5kPa, and the deposition time is 80h~250h.

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

5. The method for preparing the SiC ceramic-based composite flow channel plug according to claim 4, characterized in that: When chemical vapor infiltration is used for densification of silicon carbide matrix, the 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 8.5~10:1, the deposition temperature is 900℃~1100℃, the deposition pressure is 1kPa~4kPa, and the deposition time is 400h~500h; when the precursor pyrolysis method is used for densification of silicon carbide matrix, polycarbosilane is used as the precursor, argon atmosphere, the pyrolysis temperature is 1250℃~1400℃, and the single insulation time is 1h~3h.

6. The method for preparing the SiC ceramic-based composite flow channel plug according to claim 1, characterized in that: The deposition thickness of the β-phase silicon carbide coating is 50μm~150μm, the chemical vapor deposition precursor gas source is trichloromethylsilane, the carrier gas is argon, the dilution gas is hydrogen and argon, wherein the molar ratio of hydrogen to trichloromethylsilane is 9~11:1, the deposition temperature is 1300℃~1400℃, the deposition pressure is 3kPa~5kPa, and the deposition time is 20h~50h.

7. The method for preparing the SiC ceramic-based composite flow channel plug according to claim 1, characterized in that: The SiC prefabricated fabric is a SiC fiber fabric with a two-dimensional woven structure, and the multi-layer SiC prefabricated fabric has 8 to 10 layers.

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

9. The SiC ceramic matrix composite flow channel insert according to claim 8, characterized in that: The density of the SiC ceramic-based composite flow channel plug is ≥2.85g / cm 3 , thermal conductivity ≤5W / m·K.

10. Use of the SiC ceramic-based composite flow channel insert according to claim 8 in a fusion reactor blanket structure.

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