Multilayer hetero-clad tube based on max phase interface and method of making the same

Abstract

The application discloses a kind of multilayer hetero-encapsulated tube based on MAX phase interface and preparation method thereof, belong to nuclear fuel cladding material technical field.The cladding tube sequentially includes from inside to outside: refractory metal lining pipe, first transition layer, second transition layer and SiC / SiC composite material outer layer.The first transition layer is the composite material layer with Ti3SiC2MAX phase as matrix and SiC nanoparticles and SiC whisker as reinforcing phase;The second transition layer is SiC nanowire layer.Preparation method includes: first transition layer is formed by pulling method outside refractory metal pipe, second transition layer is formed by electrophoretic deposition method, then SiC fiber preform is woven and deposited pyrolytic carbon interface, then vacuum impregnation is carried out in SiC whisker-containing polycarbosilane solution, finally, SiC matrix is deposited by chemical vapor infiltration.The application realizes excellent thermal-mechanical performance matching between heterogeneous materials by designing two layers of transition interface with function synergy, while ensuring the high gas tightness of cladding tube.

Description

Technical Field

[0001] This invention belongs to the field of nuclear fuel cladding material technology, specifically relating to a multilayer heterogeneous cladding tube based on the MAX phase interface and its preparation method. Background Technology

[0002] Nuclear fuel cladding tubing is one of the most critical components of a nuclear reactor core. It contains nuclear fuel pellets and serves as the first line of defense, isolating the nuclear fuel from the coolant and preventing the leakage of radioactive fission products. Currently, commercial light water reactors commonly use zirconium alloys as cladding materials. However, the 2011 Fukushima nuclear accident exposed the catastrophic risk of a rapid zirconium-water reaction under severe accident conditions (such as loss of coolant), which produces hydrogen gas and triggers an explosion. Therefore, developing accident-resistant fuel (ATF) cladding materials with higher safety margins has become a global research focus in the nuclear energy field.

[0003] Continuous silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC / SiC composites) are considered ideal candidates to replace zirconium alloys due to their high melting point, low neutron absorption cross section, excellent high-temperature strength, resistance to radiation swelling, and corrosion resistance. However, since SiC / SiC composites are usually prepared by processes such as chemical vapor infiltration (CVI) or polymer impregnation pyrolysis (PIP), the matrix inevitably contains pores and microcrack networks, resulting in insufficient airtightness of the material itself, making it difficult to meet the stringent leakage rate requirements for pressure-bearing cladding pipes on its own.

[0004] To compensate for the airtightness defect of SiC / SiC composites, researchers proposed a scheme combining refractory metals with ceramic matrix composites. Although this solves the airtightness problem, it still has the following two fundamental drawbacks: Firstly, the buffer layers used (such as alumina or pyrolytic carbon) have a single function, mainly dedicated to alleviating thermal mismatch, but they have limited effect on promoting the effective transfer of mechanical loads between heterogeneous interfaces and realizing the mechanical synergy between metal and ceramic, resulting in the overall structural performance failing to achieve optimal coupling.

[0005] Secondly, its preparation process has an inherent contradiction: it relies on a long-term high-temperature chemical vapor infiltration process to densify the outer composite material. This process inevitably leads to recrystallization and embrittlement of the inner refractory metal, causing its excellent initial mechanical properties to degrade severely, thereby weakening the final performance of the composite component.

[0006] Therefore, developing a novel heterogeneous composite cladding tube structure with excellent airtightness, superior thermo-mechanical synergy, high radiation resistance, and significantly shortened preparation cycle, as well as its efficient preparation method, has become a core bottleneck that urgently needs to be overcome to promote the practical application of accident-resistant fuel cladding technology. Summary of the Invention

[0007] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides a multilayer heterogeneous cladding tube based on the MAX phase interface and its preparation method. A four-layer heterogeneous composite structure is designed, consisting of a refractory metal liner, a Ti3SiC2-based composite material transition layer, a SiC nanowire transition layer, and a SiC / SiC composite material outer layer. By designing two functionally synergistic transition interfaces (first layer: Ti3SiC2-based composite material layer, primarily for thermo-mechanical matching and strengthening; second layer: SiC nanowire layer, primarily for densification enhancement), excellent thermo-mechanical performance matching between the heterogeneous materials is achieved, and the overall preparation cycle is shortened by more than 40%. While ensuring the high airtightness of the cladding tube, the initial properties of the liner metal are effectively preserved, resulting in a significant improvement in overall performance.

[0008] The technical solution of this invention is: a multilayer heterogeneous cladding tube based on the MAX phase interface, characterized in that it comprises, from the inside to the outside: Refractory metal liner tube; The first transition layer is a MAX phase-based composite material layer bonded to the outer wall of the refractory metal liner tube, used to achieve the transition of thermal expansion coefficient and effective transfer of mechanical load between the refractory metal liner tube and the outer material. The second transition layer is a SiC nanowire layer covering the outer surface of the first transition layer, which is used to promote the deposition and densification of the outer SiC substrate. SiC / SiC composite outer layer.

[0009] A further technical solution of the present invention is: the MAX phase-based composite material layer is composed of Ti3SiC2 as the matrix and SiC nanoparticles and SiC whiskers as the reinforcing phases. A further technical solution of the present invention is that the mass ratio of the Ti3SiC2 matrix to SiC nanoparticles and SiC whiskers is 40:6:3 to 8:2:1.

[0010] A further technical solution of the present invention is: in the SiC nanowire layer, the SiC nanowires are arranged in a direction generally perpendicular to the surface of the first transition layer by electrophoretic deposition.

[0011] A further technical solution of the present invention is that the material of the refractory metal liner tube is selected from one of Mo, Re, Ta, Nb, W and Mo-Re alloy.

[0012] A further technical solution of the present invention is that the thickness of the first transition layer is 15-25 μm, and the thickness of the second transition layer is 20-30 μm.

[0013] A method for preparing the multilayer heteroclad tube based on the MAX phase interface, characterized by comprising the following steps: Step 1: Prepare a first transition layer on the outer surface of the refractory metal liner tube; Step 2: Prepare a second transition layer on the outer surface of the first transition layer; Step 3: Weave a SiC fiber preform on the outside of the component with the second transition layer, and deposit a pyrolytic carbon interface layer on the surface of the SiC fibers; Step 4: Immerse the preform with the pyrolytic carbon interface layer into a polycarbosilane precursor solution containing SiC whiskers for vacuum impregnation. Step 5: Perform chemical vapor infiltration on the preform after step 4 to deposit the SiC matrix and form the outer layer of the SiC / SiC composite material.

[0014] A further technical solution of the present invention is: step 1 includes: Step 11: Disperse SiC nanoparticles, SiC whiskers and Ti3SiC2 powder in a solvent to form a slurry; Step 12: Immerse the refractory metal liner tube in the slurry and form a coating on its outer surface by a pull-out method; Step 13: Dry the coating to form the first transition layer.

[0015] A further technical solution of the present invention is: step 2 includes: Step 21: Mix SiC nanowire powder, binder and solvent, and add surfactant to prepare electrophoresis solution; Step 22: Using the outer surface of the first transition layer as the negative electrode, electrophoretic deposition is performed in the electrophoretic solution to form a second transition layer, namely the SiC nanowire layer; Step 23: Perform heat treatment on the component with the deposited SiC nanowire layer.

[0016] A further technical solution of the present invention is as follows: in step 4, the mass ratio of SiC whiskers to polycarbosilane is 1:40 to 1:50; in step 5, the deposition temperature of chemical vapor infiltration is 1000 to 1050°C, the deposition pressure is 2 to 2.5 kPa, and the deposition time is 400 to 500 hours.

[0017] Beneficial effects The beneficial effects of this invention are as follows: 1. This invention proposes a heterogeneous composite structure of an inner refractory metal thin-walled tube and an outer SiC / SiC composite material. Due to the high airtightness, high strength, high toughness and weldability of the inner metal, the overall airtightness of the cladding tube can be effectively improved, the overall mechanical properties, strength and toughness of the cladding tube can be enhanced, and the cladding tube can be facilitated in the encapsulation and connection of the cladding tube.

[0018] 2. This invention uses a composite material with Ti3SiC2 as the matrix and SiC nanoparticles and SiC whiskers as reinforcing phases as a transition interface between the refractory metal and the SiC / SiC composite material. Ti3SiC2, as a MAX phase material, has a modulus between that of metals and ceramics, and can effectively buffer and transfer stress between the inner refractory metal layer and the outer SiC / SiC composite material layer. Furthermore, Ti3SiC2 has a lamellar structure, which is beneficial for crack deflection and significantly improves the circumferential strength of the heterogeneous composite cladding tube.

[0019] 3. This invention designs the transition interface between the refractory metal and the SiC / SiC composite material as a composite material with Ti3SiC2 as the matrix and SiC nanoparticles and SiC whiskers as reinforcing phases. The presence of the reinforcing phases significantly improves the axial strength of the transition interface. Simultaneously, the use of two different morphologies of SiC as reinforcing phases at the transition interface results in a thermal expansion coefficient between that of the refractory metal and the SiC / SiC composite material, while also effectively mitigating the generation of thermal stress within the transition interface itself. Ultimately, this leads to a matching of the overall thermodynamic properties of the heterogeneous composite cladding tube.

[0020] 4. This invention further involves the electrophoretic directional deposition of a layer of SiC nanowires on the outer side of the transition interface. The SiC nanowires can directly contact the outer fiber preform. The loose network structure formed by the nanowires fills and divides the structural pores caused by the fiber weaving process into small regions that do not hinder the inward permeation of reactive gases. Compared with SiC fiber bundles, nanowires have a larger specific surface area, providing a large number of effective deposition areas for SiC matrix deposition. During CVI deposition, the deposition rate in the nanowire region is higher than that in the fiber bundle region, increasing the deposition rate in the internal region of the tubular preform. This avoids excessively rapid densification of the preform surface during CVI, which could cause "shelling" and prevent the infiltration reaction in the internal region. This accelerates the densification process of the cladding tube.

[0021] 5. In this invention, the cladding tube fiber preform is vacuum impregnated with SiC whiskers and polycarbosilane to divide the gaps between the fiber bundles, thereby increasing the adhesion points for subsequent SiC deposition and growth, and further accelerating the densification process. This can shorten the preparation cycle by 40%, which reduces production costs while maintaining the excellent initial properties of the refractory metal thin-walled tube.

[0022] 6. This invention combines dip-coating, electrophoretic directional deposition, and vacuum dip-coating technologies, which is simple, quick, and reduces production costs. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the fabrication method of the multilayer heterostructure cladding tube based on the MAX phase interface in an embodiment of the present invention. Figure 2 This is a schematic diagram of the transition interface of the heterogeneous composite cladding tube of the present invention.

[0024] Figure 3 The image shows a physical picture of the heterogeneous composite clad tube prepared according to the present invention. The left side is the cross-section of the heterogeneous composite clad tube, and the right side is the side of the heterogeneous composite clad tube.

[0025] Figure 4 Macroscopic morphology images of the refractory metal thin-walled tube after two transition interfaces are prepared. (a) The refractory metal thin-walled tube after grinding and cleaning; (b) The refractory metal thin-walled tube after the preparation of the first transition interface, the Ti3SiC2-based composite material layer is dark gray; (c) The refractory metal thin-walled tube after the preparation of the second transition interface, the SiC nanowire layer is silvery white.

[0026] Figure 5 This is a microscopic image of the first transition interface, captured using a scanning electron microscope. The thickness of the first transition interface is approximately 25 μm and is uniform.

[0027] Figure 6 This is a scanning electron microscope (SEM) image showing the microstructure of the second transition interface. The second transition interface has a thickness of approximately 22 μm, is uniform in thickness, and the SiC nanowires are attached to the first transition interface in an intercalation manner.

[0028] Figure 7 This is a schematic diagram showing the comparison of the circumferential strength of four different types of heterogeneous composite cladding tubes.

[0029] Figure 8 Cross-sectional images of the heterogeneous composite cladding tubes prepared for comparative purposes after 50 thermal shocks at room temperature to 1200°C. (a) Comparative Example 1, (b) Comparative Example 2.

[0030] Explanation of reference numerals in the attached figures: 1 represents the inner layer of refractory metal thin-walled tube; 2 represents the first transition interface, Ti3SiC2-based composite material layer; 3 represents the second transition interface, SiC nanowire layer; 4 represents the outer layer of SiC / SiC composite material. Detailed Implementation The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0031] To address the thermo-mechanical mismatch at metal / ceramic heterojunctions, researchers have attempted to design functionally graded interfaces or introduce novel interface materials. Patent document CN113571209A proposes preparing a Mo-Si compositional gradient layer between Mo metal and SiC / SiC to improve interfacial bonding and thermal stress distribution. However, such metal silicides may still generate new stress concentrations at high temperatures due to incompatibility with the properties of the materials on both sides. On the other hand, MAX phase materials, represented by Ti3SiC2, have attracted attention in the field of composite material interfaces due to their unique nanolayered structure and excellent properties combining those of metals and ceramics (such as good thermal and electrical conductivity, a certain degree of damage tolerance, and high-temperature stability). Patent document CN112479718B discloses depositing a Ti3SiC2 MAX phase as an interfacial coating on the surface of SiC fibers to improve the high-temperature oxidation resistance and mechanical properties of the composite material. However, this technology only applies Ti3SiC2 to micrometer-scale fiber coatings and does not address how to use it as a macroscopic transition layer with specific thickness and composite structure to solve the overall performance matching problem between millimeter-scale metal tubes and ceramic composite tubes.

[0032] In terms of optimizing the fabrication process, shortening the densification cycle of SiC / SiC composite materials is a key challenge. Patent document CN106083116A proposes introducing one-dimensional SiC nanomaterials (such as nanowires) into the inner layer of the fiber preform, utilizing the difference in densification rate between the nanomaterials and the fiber bundles during CVI to improve densification uniformity. This approach primarily aims to prevent "shell formation," but it does not fundamentally solve the problem of a long overall deposition cycle, nor is it integrated with the design of heterogeneous composite structures.

[0033] To address the aforementioned problems, this invention provides a multilayer heteroclad tube based on a MAX phase interface, comprising, from the inside out: Refractory metal liner tube; The first transition layer is a MAX phase-based composite material layer bonded to the outer wall of the refractory metal liner tube, used to achieve the transition of thermal expansion coefficient and effective transfer of mechanical load between the refractory metal liner tube and the outer material. The second transition layer is a SiC nanowire layer covering the outer surface of the first transition layer, which is used to promote the deposition and densification of the outer SiC substrate. SiC / SiC composite outer layer.

[0034] Preferably, the MAX phase-based composite material layer is composed of Ti3SiC2 as the matrix and SiC nanoparticles and SiC whiskers as reinforcing phases. Preferably, the mass ratio of the Ti3SiC2 matrix to SiC nanoparticles and SiC whiskers is 40:6:3.

[0035] Preferably, in the SiC nanowire layer, the SiC nanowires are arranged in a direction generally perpendicular to the surface of the first transition layer by electrophoretic deposition.

[0036] Preferably, the thickness of the first transition layer is 25 μm and the thickness of the second transition layer is 22 μm.

[0037] This invention also proposes a method for preparing the multilayer heteroclad tube based on the MAX phase interface, comprising the following steps: Step 1: Prepare a first transition layer on the outer surface of the refractory metal liner tube; Step 2: Prepare a second transition layer on the outer surface of the first transition layer; Step 3: Weave a SiC fiber preform on the outside of the component with the second transition layer, and deposit a pyrolytic carbon interface layer on the surface of the SiC fibers; Step 4: Immerse the preform with the pyrolytic carbon interface layer into a polycarbosilane precursor solution containing SiC whiskers for vacuum impregnation. Step 5: Perform chemical vapor infiltration on the preform after step 4 to deposit the SiC matrix and form the outer layer of the SiC / SiC composite material.

[0038] The above technical solution will be further analyzed below with reference to the accompanying drawings and examples: Example 1 Reference Figure 1 As shown, this embodiment provides a multilayer heterogeneous composite material cladding tube and its preparation method. The specific implementation steps are as follows: Step 1: Mix and disperse SiC nanoparticles and SiC whiskers in a solvent at a mass ratio of 2:1. The solvent consists of deionized water and anhydrous ethanol in a volume ratio of 2:1. The mass ratio of SiC nanoparticles to SiC whiskers to solvent is 2:1:50. Add 6% of the total mass of dispersant.

[0039] In this embodiment, the SiC nanoparticles are 1g and the SiC whiskers are 0.5g. The total volume of the solvent is 25ml, and the dispersant is 1.5g of sodium hexametaphosphate. It should be noted that this embodiment does not limit the type of dispersant, as long as it can disperse the above substances. Impurities introduced into the solution by the dispersant in this embodiment can be removed in the subsequent heat treatment.

[0040] Step 2: Sonicate the solution obtained in Step 1 for 1 hour to ensure thorough dispersion, then add Ti3SiC2. The mass ratio of Ti3SiC2 to SiC nanoparticles and to SiC whiskers is 40:6:3. Continue sonicating for 3 hours to ensure uniform mixing.

[0041] In this embodiment, the mass of Ti3SiC2 added is 6.7g. It should be noted that this embodiment does not limit the ultrasonication time, as long as the solution is fully and uniformly dispersed.

[0042] Step 3: Place the solution obtained in step 2 in an oven and dry it into powder at 120°C.

[0043] It should be noted that this embodiment does not limit the specific drying method.

[0044] Step 4: Mix PVA and polyethylene glycol with deionized water at a mass ratio of 5:1:100 and sonicate for 30 minutes to form a clear solution; In this embodiment, the mass of PVA is 5g, the mass of polyethylene glycol is 1g, and the mass of deionized water is 100g. Adding polyethylene glycol helps to prevent cracking of the transition interface in subsequent preparations. This embodiment does not limit the sonication time, as long as the PVA and polyethylene glycol are fully dissolved in the deionized water.

[0045] Step 5: Add the PVA aqueous solution to the mixed powder formed in Step 3, with a mass ratio of PVA aqueous solution to powder of 15:1. Add the plasticizer, with a mass ratio of plasticizer to powder of 1:2. Sonicate for 1 hour to form a suspension.

[0046] In this embodiment, the mass of the PVA aqueous solution is 15g, and the mass of the powder is 1g. The plasticizer used in this embodiment is dioctyl phthalate, with a mass of 0.5g. The introduced impurities can be removed during the subsequent heat treatment process.

[0047] Step 6: Polish the outer wall of the refractory metal thin-walled tube with 1000-grit sandpaper and perform ultrasonic cleaning in anhydrous ethanol. Immerse the cleaned refractory metal thin-walled tube in the suspension formed in Step 5 and pull it upwards at a speed of 5 mm / min to form a uniform transition interface.

[0048] In this embodiment, the refractory metal used is Re, with a wall thickness of 0.3 mm, an outer diameter of 10.6 mm, and two lifting operations. The resulting interface thickness is approximately 25 μm. Figure 5 As shown.

[0049] Step 7: Allow the refractory metal thin-walled tube with the interface prepared in Step 6 to air dry at room temperature for 24 hours.

[0050] This embodiment does not limit the specific drying time, as long as the transition interface is completely dry.

[0051] Step 8: Mix SiC nanowires with anhydrous ethanol at a mass ratio of 1:50, and add a coupling agent with a mass ratio of 1:1 to the SiC nanowires.

[0052] In this embodiment, the mass of SiC nanowires is 1g, and the mass of anhydrous ethanol is 50g. The coupling agent used is KH-550, with a mass of 1g. It should be noted that this embodiment does not limit the type of coupling agent, as long as it prevents the SiC nanowires from agglomerating. Impurities introduced by the coupling agent in this embodiment can be completely removed during subsequent heat treatment.

[0053] Step 9: Stir the SiC nanowires obtained in Step 8 at 80°C for 10 hours to allow them to react fully.

[0054] It should be noted that the specific stirring method is not limited in this embodiment, as long as the coupling agent reacts completely. In this embodiment, magnetic stirring is used for dispersion, and the stirring speed is 300 rpm.

[0055] Step 10: Centrifuge the solution formed in step 9 at a speed of 8000-10000 r / min, wash and dry to obtain SiC nanowire powder.

[0056] In this embodiment, the centrifuge speed is 8000 r / min, anhydrous ethanol is used, and the centrifuge is cleaned 3 times.

[0057] Step 11: Mix the SiC nanowire powder obtained in Step 11 with PVA powder and isopropanol solvent at a mass ratio of 2:1:250, and add a surfactant with a mass ratio of surfactant to SiC nanowire powder of 1:20. Stir for 30 minutes to disperse the mixture evenly and form an electrophoretic solution.

[0058] In this embodiment, the amount of SiC nanowire powder is 0.8g, PVA powder is 0.4g, and isopropanol solution is 100g. The surfactant used is hexadecyltrimethylammonium bromide, with a mass of 0.04g. It should be noted that this embodiment does not limit the specific type of surfactant, as long as it enables the surface of the SiC nanowires to carry a charge.

[0059] Step 12: Four graphite rods are used as positive electrodes, and the naturally dried refractory metal tube from Step 7 is used as the negative electrode. The graphite electrodes are evenly placed around the refractory metal rods and directionally deposited in the electrophoretic solution obtained in Step 11, so that a layer of SiC nanowires is deposited on the interface surface of the refractory metal tube. The voltage for electrophoretic directional deposition is 80V, and the deposition time is 10min.

[0060] In this embodiment, the thickness of the directionally deposited SiC nanowires is approximately 22 μm, such as Figure 6 As shown.

[0061] Step 13: Heat-treat the refractory metal tube obtained in step 12 at 1200℃ under an argon atmosphere for 2 hours.

[0062] In this embodiment, the specific method of heat treatment is not limited. In this embodiment, heat treatment is performed in a tube furnace. The heating rate is 2°C / min.

[0063] Step 14: Cross-weave SiC fiber bundles into the heat-treated refractory metal tube.

[0064] In this embodiment, the SiC fiber linear density is 150Tex, the weaving angle is 67.5° / 112.5°, the weaving thickness is 0.68mm, and the fiber volume fraction is 30%.

[0065] Step 15: Perform PyC interface deposition on the woven sheathed fiber preform from Step 14. Chemical vapor deposition (CVD) is used, with propylene as the precursor gas and argon as the dilution gas.

[0066] In this embodiment, the deposition temperature is 900℃, the deposition pressure is 2kPa, and the deposition time is 96h.

[0067] Step 16: Mix SiC whiskers and polycarbosilane at a mass ratio of 1:50, and stir until homogeneous. In this embodiment, the mass of SiC whiskers is 1g, and the mass of polycarbosilane is 50g. The specific stirring method is not limited in this embodiment, as long as the SiC whiskers are fully dispersed. Magnetic stirring is used in this embodiment at a speed of 400 rpm for 5 hours.

[0068] Step 17: Vacuum impregnate the cladding fiber preform with PyC interface deposited in Step 15 into the mixed solution of SiC whiskers and polycarbosilane obtained in Step 16 for 5 hours.

[0069] Step 18: The vacuum-impregnated cladding fiber preform is subjected to SiC matrix deposition, using trichloromethylsilane (C3H3SiCl) as the source gas, hydrogen as the carrier gas, and hydrogen and argon as dilution gases. This completes the preparation of the outermost SiC / SiC composite material. In this embodiment, the deposition temperature is 1020℃, the deposition pressure is 2kPa, and the deposition time is 480h; the molar ratio of hydrogen to trichloromethylsilane is 10:1; the carrier gas hydrogen flow rate is 3L / min; the dilution hydrogen flow rate is 1L / min; and the dilution argon flow rate is 3L / min.

[0070] Based on the above preparation method, a multilayer heterogeneous cladding tube based on the MAX phase interface of the present invention is obtained, which, from the inside to the outside, comprises: a Re metal inner liner tube, a Ti3SiC2-based composite material layer, a SiC nanowire layer, and a SiC / SiC composite material outer layer, as shown below. Figure 2 - Figure 4 As shown.

[0071] Example 2 This embodiment provides a multilayer heterogeneous composite material cladding tube and its preparation method, which differs from Embodiment 1 in that: In this embodiment, the selected refractory metal is Mo-47.5Re metal, with a wall thickness of 0.35 mm, an outer diameter of 10.8 mm, and 3 lifting cycles, resulting in an interface thickness of approximately 35 μm.

[0072] Based on the above preparation method, a multilayer heterogeneous cladding tube based on the MAX phase interface of the present invention is obtained, which includes, from the inside to the outside: a Mo-47.5Re metal inner liner tube, a Ti3SiC2-based composite material layer, a SiC nanowire layer, and a SiC / SiC composite material outer layer.

[0073] Example 3 This embodiment provides a multilayer heterogeneous composite material cladding tube and its preparation method, which differs from Embodiment 1 in that: In this embodiment, the selected refractory metal is Ta metal, with a wall thickness of 0.3 mm, an outer diameter of 10.8 mm, and 3 lifting cycles, resulting in an interface thickness of approximately 35 μm.

[0074] In this embodiment, the electrophoretic directional deposition voltage was 100V, and the deposition time was 10 minutes. The thickness of the deposited SiC nanowires was approximately 30 μm.

[0075] Based on the above preparation method, a multilayer heterogeneous cladding tube based on the MAX phase interface of the present invention is obtained, which includes, from the inside to the outside: a Ta metal inner liner tube, a Ti3SiC2-based composite material layer, a SiC nanowire layer, and a SiC / SiC composite material outer layer.

[0076] Comparative Example 1 This comparative example prepares a multilayer heterogeneous cladding tube, which, from the inside out, includes: a Re metal inner liner, a Ti3SiC2-based composite material transition layer, and a SiC / SiC composite material outer layer.

[0077] Step 1: Prepare the first layer of Ti3SiC2-based composite material transition interface. The preparation method is the same as steps 1 to 7 in Example 1.

[0078] Step 2: The refractory metal tube impregnated with the first Ti3SiC2-based composite layer transition interface is cross-woven with SiC fiber bundles.

[0079] In this comparative example, the SiC fiber linear density is 150Tex, the braiding angle is 67.5° / 112.5°, the braiding thickness is 0.68mm, and the fiber volume fraction is 30%.

[0080] Step 3: Perform PyC interface deposition on the woven sheathed fiber preform from Step 2. Chemical vapor deposition (CVD) is used, with propylene as the precursor gas and argon as the dilution gas.

[0081] In this comparative example, the deposition temperature was 900℃, the deposition pressure was 2kPa, and the deposition time was 96h.

[0082] Step 4: SiC matrix deposition is performed on the cladding fiber preform using trichloromethylsilane (C3H3SiCl) as the source gas, hydrogen as the carrier gas, and hydrogen and argon as dilution gases. This completes the preparation of the outermost SiC / SiC composite material. In this comparative example, the deposition temperature was 1020℃, the deposition pressure was 2kPa, and the deposition time was 480h; the molar ratio of hydrogen to trichloromethylsilane was 10:1; the flow rate of the carrier gas hydrogen was 3L / min; the flow rate of the dilution hydrogen was 1L / min; and the flow rate of the dilution argon was 3L / min.

[0083] Comparative Example 2 This comparative example prepares a multilayer heterogeneous cladding tube, which, from the inside out, includes: a Re metal inner liner, a Ti3SiC2 layer, and a SiC / SiC composite material outer layer.

[0084] Step 1: Mix PVA and polyethylene glycol with deionized water at a mass ratio of 5:1:100 and sonicate for 30 minutes to form a clear solution; In this comparative example, the mass of PVA was 5g, the mass of polyethylene glycol was 1g, and the mass of deionized water was 100g. The addition of polyethylene glycol helps to prevent cracking at the transition interface during subsequent preparation.

[0085] This comparative example does not limit the ultrasound time, as long as PVA and polyethylene glycol are fully dissolved in deionized water.

[0086] Step 2: Add PVA aqueous solution to Ti3SiC2 powder at a mass ratio of 15:1. Add plasticizer at a mass ratio of 1:2. Sonicate for 1 hour to form a suspension.

[0087] In this comparative example, the mass of the PVA aqueous solution was 15g, and the mass of the Ti3SiC2 powder was 1g. The plasticizer used in this comparative example was dioctyl phthalate, with a mass of 0.5g. The introduced impurities can be removed during the subsequent heat treatment process.

[0088] Step 3: Polish the outer wall of the refractory metal thin-walled tube with 1000-grit sandpaper and perform ultrasonic cleaning in anhydrous ethanol. Immerse the cleaned refractory metal thin-walled tube in the suspension formed in Step 2 and pull it upwards at a speed of 5 mm / min to form a uniform transition interface.

[0089] Step 4: Heat-treat the refractory metal tube obtained in Step 3 at 1200℃ under an argon atmosphere for 2 hours.

[0090] In this comparative example, the specific method of heat treatment is not limited. The heat treatment in this comparative example was carried out in a tube furnace. The heating rate was 2℃ / min.

[0091] Step 5: The refractory metal tube impregnated with the first Ti3SiC2 transition interface is cross-woven with SiC fiber bundles.

[0092] In this comparative example, the SiC fiber linear density is 150Tex, the braiding angle is 67.5° / 112.5°, the braiding thickness is 0.68mm, and the fiber volume fraction is 30%.

[0093] Step 6: Perform PyC interface deposition on the woven sheathed fiber preform from Step 5. Chemical vapor deposition (CVD) is used, with propylene as the precursor gas and argon as the dilution gas.

[0094] In this comparative example, the deposition temperature was 900℃, the deposition pressure was 2kPa, and the deposition time was 96h.

[0095] Step 7: Deposit SiC matrix onto the cladding fiber preform using trichloromethylsilane (C3H3SiCl) as the source gas, hydrogen as the carrier gas, and hydrogen and argon as dilution gases. This completes the preparation of the outermost SiC / SiC composite material. In this comparative example, the deposition temperature was 1020℃, the deposition pressure was 2kPa, and the deposition time was 480h; the molar ratio of hydrogen to trichloromethylsilane was 10:1; the flow rate of the carrier gas hydrogen was 3L / min; the flow rate of the dilution hydrogen was 1L / min; and the flow rate of the dilution argon was 3L / min.

[0096] Comparative Example 3 This comparative example prepares a multilayer heterogeneous cladding tube, which, from the inside out, includes: a Re metal inner liner, a SiC nanowire layer, and a SiC / SiC composite material outer layer.

[0097] Step 1: Mix SiC nanowires with anhydrous ethanol at a mass ratio of 1:50, and add a coupling agent with a mass ratio of 1:1 to the SiC nanowires.

[0098] In this comparative example, the mass of SiC nanowires is 1 g, and the mass of anhydrous ethanol is 50 g. The coupling agent used is KH-550, with a mass of 1 g. It should be noted that this comparative example does not limit the type of coupling agent, as long as it prevents the SiC nanowires from agglomerating. Impurities introduced by the coupling agent in this comparative example can be completely removed during subsequent heat treatment.

[0099] Step 2: Stir the SiC nanowires obtained in Step 1 at 80°C for 10 hours to allow them to react fully.

[0100] It should be noted that the specific stirring method is not limited in this comparative example, as long as the coupling agent reacts completely. In this comparative example, magnetic stirring is used for dispersion, and the stirring speed is 300 rpm.

[0101] Step 3: Centrifuge the solution formed in Step 2 at a speed of 8000-10000 r / min, wash and dry to obtain SiC nanowire powder.

[0102] In this comparative example, the centrifuge speed was 8000 r / min, anhydrous ethanol was used, and the centrifuge was cleaned 3 times.

[0103] Step 4: Mix the SiC nanowire powder obtained in Step 11 with PVA powder and isopropanol solvent at a mass ratio of 2:1:250, and add a surfactant with a mass ratio of surfactant to SiC nanowire powder of 1:20. Stir for 30 minutes to disperse the mixture evenly and form an electrophoretic solution.

[0104] In this comparative example, the amount of SiC nanowire powder was 0.8 g, PVA powder was 0.4 g, and isopropanol solution was 100 g. The surfactant used was hexadecyltrimethylammonium bromide, with a mass of 0.04 g. It should be noted that the specific type of surfactant is not limited in this comparative example, as long as it enables the surface of the SiC nanowires to carry a charge.

[0105] Step 5: Four graphite rods are used as positive electrodes, and a refractory metal tube is used as the negative electrode. The graphite electrodes are evenly placed around the refractory metal rods and directionally deposited in the electrophoretic solution obtained in step 4, so that a layer of SiC nanowires is deposited on the interface surface of the refractory metal tube. The voltage for electrophoretic directional deposition is 80V, and the deposition time is 10min.

[0106] In this comparative example, the thickness of the directionally deposited SiC nanowires is approximately 22 μm.

[0107] Step 6: Heat-treat the refractory metal tube obtained in Step 5 at 1200℃ under an argon atmosphere for 2 hours.

[0108] In this comparative example, the specific method of heat treatment is not limited. The heat treatment in this comparative example was carried out in a tube furnace. The heating rate was 2℃ / min.

[0109] Step 7: Cross-weave SiC fiber bundles into the heat-treated refractory metal tube.

[0110] In this comparative example, the SiC fiber linear density is 150Tex, the braiding angle is 67.5° / 112.5°, the braiding thickness is 0.68mm, and the fiber volume fraction is 30%.

[0111] Step 8: Perform PyC interface deposition on the woven sheathed fiber preform from Step 7. Chemical vapor deposition (CVD) is used, with propylene as the precursor gas and argon as the dilution gas.

[0112] In this comparative example, the deposition temperature was 900℃, the deposition pressure was 2kPa, and the deposition time was 96h.

[0113] Step 9: Mix SiC whiskers and polycarbosilane at a mass ratio of 1:50, and stir until homogeneous. In this comparative example, the mass of SiC whiskers is 1g, and the mass of polycarbosilane is 50g. The specific stirring method is not limited in this comparative example, as long as the SiC whiskers are fully dispersed. Magnetic stirring was used in this comparative example at a speed of 400 rpm for 5 hours.

[0114] Step 10: Vacuum impregnate the cladding fiber preform with PyC interface deposited in Step 15 into the mixed solution of SiC whiskers and polycarbosilane obtained in Step 16 for 5 hours.

[0115] Step 11: The vacuum-impregnated cladding fiber preform is subjected to SiC matrix deposition, using trichloromethylsilane (C3H3SiCl) as the source gas, hydrogen as the carrier gas, and hydrogen and argon as dilution gases. This completes the preparation of the outermost SiC / SiC composite material. In this comparative example, the deposition temperature was 1020℃, the deposition pressure was 2kPa, and the deposition time was 480h; the molar ratio of hydrogen to trichloromethylsilane was 10:1; the flow rate of the carrier gas hydrogen was 3L / min; the flow rate of the dilution hydrogen was 1L / min; and the flow rate of the dilution argon was 3L / min.

[0116] Table 1 shows the preparation cycle and porosity results of the four types of heterogeneous composite cladding tubes. Figure 7 The results of the circumferential strength of the four types of heterogeneous composite cladding tubes are presented. Figure 8 Image (a) shows a cross-sectional image of the heterogeneous composite cladding tube prepared in Comparative Example 1 after 50 thermal shocks at room temperature to 1200℃. Figure 8 Image (b) shows a cross-sectional image of the heterogeneous composite cladding tube prepared in Comparative Example 2 after 50 thermal shocks at room temperature to 1200℃.

[0117] Table 1 Preparation cycle and porosity

[0118] From Table 1 and Figure 7It can be seen that the preparation cycle of Comparative Example 1 and Comparative Example 2 is significantly increased, and the mechanical properties are reduced by more than half compared with Example 1. This indicates that the heterogeneous composite cladding tube prepared by the present invention with SiC nanowire layer and vacuum impregnation with SiC whisker and polycarbosilane mixed solution can greatly retain the original mechanical properties of refractory metal tube while shortening the preparation cycle, thus significantly improving the final mechanical properties of the heterogeneous composite cladding tube.

[0119] As can be seen from Table 1, the porosity of both Example 1 and Comparative Example 3 is below 10%, indicating that the heterogeneous composite shell tube prepared by the present invention using SiC nanowire layers and vacuum impregnation with a mixed solution of SiC whiskers and polycarbosilane can shorten the preparation cycle and improve the density, thus greatly improving the preparation efficiency.

[0120] from Figure 7 It can be seen that the mechanical properties of Comparative Example 1 are better than those of Comparative Example 2. This indicates that the composite material prepared in this invention, with Ti3SiC2 as the matrix and SiC nanoparticles and SiC whiskers as the reinforcing phases, has better mechanical properties as a transition interface than Ti3SiC2 alone.

[0121] from Figure 8 It is evident that in Comparative Example 2, the inner refractory metal layer and the outer SiC / SiC composite material layer of the heterogeneous composite cladding tube exhibit significant crack formation, indicating a mismatch in thermal properties between the inner and outer layers, along with substantial thermal stress at the interface. In contrast, the inner refractory metal layer and the outer SiC / SiC composite material layer of the heterogeneous composite cladding tube prepared in Comparative Example 1 show better bonding, with no obvious crack formation. This demonstrates that the composite material prepared in this invention, using Ti3SiC2 as the matrix and SiC nanoparticles and SiC whiskers as reinforcing phases, effectively mitigates the thermal stress at the transition interface, resulting in a more balanced overall thermal performance of the heterogeneous composite cladding tube.

[0122] Compared with Comparative Examples 1 to 3, the multilayer heterostructure tube based on the MAX phase interface and its preparation method provided by the present invention have significant advantages in terms of comprehensive performance and preparation efficiency.

[0123] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A multilayer heteroclad tube based on the MAX phase interface, characterized in that, From the inside out, the following are included: Refractory metal liner tube; The first transition layer is a MAX phase-based composite material layer bonded to the outer wall of the refractory metal liner tube, used to achieve the transition of thermal expansion coefficient and effective transfer of mechanical load between the refractory metal liner tube and the outer material. The second transition layer is a SiC nanowire layer covering the outer surface of the first transition layer, which is used to promote the deposition and densification of the outer SiC substrate. SiC / SiC composite outer layer.

2. The multilayer heteroclad tube based on the MAX phase interface according to claim 1, characterized in that: The MAX phase-based composite material layer is composed of Ti3SiC2 as the matrix and SiC nanoparticles and SiC whiskers as the reinforcing phases.

3. The multilayer heteroclad tube based on the MAX phase interface according to claim 2, characterized in that: The mass ratio of the Ti3SiC2 matrix to SiC nanoparticles and SiC whiskers is 40:6:3 to 8:2:

1.

4. The multilayer heteroclad tube based on the MAX phase interface according to claim 1, characterized in that: In the SiC nanowire layer, the SiC nanowires are arranged in a direction that is generally perpendicular to the surface of the first transition layer by electrophoretic deposition.

5. The multilayer heteroclad tube based on the MAX phase interface according to claim 4, characterized in that: The refractory metal liner is made of one of the following materials: Mo, Re, Ta, Nb, W, and Mo-Re alloys.

6. The multilayer heteroclad tube based on the MAX phase interface according to claim 5, characterized in that: The thickness of the first transition layer is 15–25 μm, and the thickness of the second transition layer is 20–30 μm.

7. A method for preparing a multilayer heteroclad tube based on a MAX phase interface as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Prepare a first transition layer on the outer surface of the refractory metal liner tube; Step 2: Prepare a second transition layer on the outer surface of the first transition layer; Step 3: Weave a SiC fiber preform on the outside of the component with the second transition layer, and deposit a pyrolytic carbon interface layer on the surface of the SiC fibers; Step 4: Immerse the preform with the pyrolytic carbon interface layer into a polycarbosilane precursor solution containing SiC whiskers for vacuum impregnation. Step 5: Perform chemical vapor infiltration on the preform after step 4 to deposit the SiC matrix and form the outer layer of the SiC / SiC composite material.

8. The method according to claim 7, characterized in that: Step 1 includes: Step 11: Disperse SiC nanoparticles, SiC whiskers and Ti3SiC2 powder in a solvent to form a slurry; Step 12: Immerse the refractory metal liner tube in the slurry and form a coating on its outer surface by a pull-out method; Step 13: Dry the coating to form the first transition layer.

9. The method according to claim 7, characterized in that: Step 2 includes: Step 21: Mix SiC nanowire powder, binder and solvent, and add surfactant to prepare electrophoresis solution; Step 22: Using the outer surface of the first transition layer as the negative electrode, electrophoretic deposition is performed in the electrophoretic solution to form a second transition layer, namely the SiC nanowire layer; Step 23: Perform heat treatment on the component with the deposited SiC nanowire layer.

10. The method according to claim 7, characterized in that: In step 4, the mass ratio of SiC whiskers to polycarbosilane is 1:40 to 1:50; in step 5, the chemical vapor infiltration deposition temperature is 1000 to 1050°C, the deposition pressure is 2 to 2.5 kPa, and the deposition time is 400 to 500 hours.

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