1500 DEG C-resistant ceramic-based composite material and preparation method thereof

Abstract

The invention discloses a 1500 DEG C-resistant ceramic-based composite material and a preparation method thereof, and belongs to the technical field of high-temperature structural materials. The method comprises the following steps: selecting metal-doped high-temperature-resistant silicon carbide fibers to form a preform; depositing a Ti3SiC2 interface layer on the surface of the fiber, and carrying out heat treatment at 1200-1500 DEG C; and then sequentially carrying out chemical vapor deposition on a SiC matrix, dipping ceramic powder with slurry and dipping and pyrolyzing a metal modified precursor on the prefabricated body to obtain the final composite material. The composite material comprises a preform formed by the SA type fiber, a Ti3SiC2 interface layer covering the surface of the fiber, and a composite matrix filling and coating the fiber. Through the systematic design of the high-temperature-resistant fibers, the reinforced interface and the synergistic densification matrix, the prepared material has excellent mechanical properties and long-term stability in air at the temperature of 1500 DEG C, and is suitable for ultrahigh-temperature hot-end components such as aero-engines and gas turbines.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature structural materials technology, specifically relating to a ceramic matrix composite material that can serve for a long time in an ultra-high temperature (≥1500℃) oxidizing environment and its preparation method, which is particularly suitable for extreme environments such as aero-engines, hot-end components of gas turbines and nuclear reactor cladding tubes. Background Technology

[0002] Increasing turbine inlet temperature is a crucial means to improve the thrust-to-weight ratio, fuel efficiency, and reduce emissions of aero-engines and gas turbines. When the temperature reaches or exceeds the upper limit of the temperature resistance of hot-end components of the engine, the selection of lightweight, high-strength, high-temperature resistant, and oxidation-resistant materials is critical. Currently, the main high-temperature resistant materials include nickel-based, cobalt-based superalloys, and ceramic matrix composites. Ceramic matrix composites, due to their low density, high specific strength, and excellent high-temperature resistance, have become key candidate materials for next-generation aero-engine hot-end components. Ceramic matrix composites are composed of ceramic reinforcing fibers embedded in a ceramic matrix. Currently, the long-term service temperature of ceramic fibers (second and third generation) used in China typically does not exceed 1400℃, while traditional pyrolytic carbon or h-BN interface layers are prone to failure in oxidizing environments above 800℃, and the matrix lacks sufficient cracking stress at high temperatures. These factors collectively restrict the application of ceramic matrix composites in ultra-high temperature environments of 1500℃ and above.

[0003] In existing technologies, some MAX phases such as Ti3SiC2 are introduced as interface layers to improve oxidation resistance. However, the upper limit of the temperature resistance of the reinforcing fibers on which they rely is low, and the interface layer is not specifically optimized. Therefore, the overall design cannot meet the stringent requirements of long-term service at 1500℃. Currently, the main preparation processes for ceramic matrix composites include prepreg-melt infiltration (PP-MI), chemical vapor deposition (CVI), resin impregnation pyrolysis, and their combinations (CVI-MI or CVI-PIP). Melt infiltration produces residual silicon, and due to the melting point of silicon (1405℃), the service temperature of the prepared ceramic matrix composites generally cannot exceed 1400℃. CVI-PIP can effectively reduce the temperature of the preparation process, obtaining a low-porosity ceramic matrix for the preparation of ultra-high temperature ceramic matrix composites. However, because the high-temperature matrix cracking stress after the pyrolysis of silicon-containing precursor resin is relatively low, resin modification is required to improve the overall performance of the material at high temperatures.

[0004] Therefore, there is an urgent need to develop a ceramic matrix composite material that can withstand long-term oxidation at 1500℃ and its efficient preparation method, which involves systematic design and synergistic reinforcement from fibers, interfaces to the matrix. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a ceramic matrix composite material resistant to 1500℃ and its preparation method. This material achieves excellent mechanical properties and structural integrity even after long-term (≥300 hours) service in an air atmosphere at 1500℃ through synergistic reinforcement at three levels: reinforcing fibers, interface layer, and matrix.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a ceramic matrix composite material resistant to 1500℃, the method comprising the following steps: First, high-temperature-resistant silicon carbide fibers doped with metal are selected to form fiber preforms. This step ensures the thermal stability of the reinforcement at 1500℃ from the material itself, and is the cornerstone for constructing the entire ultra-high temperature composite material system; Secondly, a Ti3SiC2 interface layer is deposited on the fiber surface of the fiber preform, followed by heat treatment at 1200–1500 °C. This step introduces a MAX phase, which combines the advantages of both metals and ceramics, as the interface layer, and optimizes its crystallization state and bonding strength through high-temperature heat treatment, thereby significantly improving the stability and toughness transfer capability of the interface layer in ultra-high temperature oxidizing environments. Finally, the fiber preform with the deposited Ti3SiC2 interface layer and after heat treatment is subjected to sequential chemical vapor deposition of the SiC matrix, slurry impregnation of ceramic powder, and metal-modified precursor impregnation pyrolysis to obtain the 1500℃-resistant ceramic matrix composite material. This composite densification step first constructs an initial, complete SiC matrix framework through chemical vapor deposition; then, slurry impregnation introduces a specific ratio of refractory ceramic powder to initially fill the pores and adjust the matrix properties; finally, through impregnation and pyrolysis of the metal-modified precursor, a high-entropy ceramic phase is introduced at the molecular scale, achieving final densification and endowing the matrix with excellent high-temperature oxidation and creep resistance. These three sub-steps are performed sequentially and synergistically, effectively solving a series of problems such as large preform porosity due to the small diameter of SA-type fibers, mismatch of matrix thermal expansion coefficients, and low high-temperature cracking stress.

[0007] Preferably, the metal-doped high-temperature-resistant silicon carbide fiber is an SA-type silicon carbide fiber with added Al or an ST-type silicon carbide fiber with added Ti. The doping of Al or Ti effectively suppresses abnormal grain growth and high-temperature creep of silicon carbide fibers at ultra-high temperatures, increasing their intrinsic temperature resistance limit to over 1500℃, providing a stable and reliable mechanical basis for the entire composite material system. Furthermore, SA-type and ST-type fibers can achieve high crystallinity and high modulus through specific metal doping. This selection ensures excellent structural and performance retention of the reinforcement in extreme thermo-mechanical-oxidative coupling environments, fundamentally overcoming the overall material failure caused by the premature degradation of fibers when using ordinary SiC fibers (temperature resistance ≤1400℃), providing a temperature-resistant foundation for subsequent interface optimization and matrix co-design.

[0008] Preferably, the silicon carbide fiber has a grain size of 30-120 nm and a fiber bundle number of 500-1000 fibers per bundle; the fiber volume fraction of the fiber preform is 35%-45%. This grain size range ensures the high-temperature strength and stability of the fiber, while a suitable fiber volume fraction is the basis for achieving high mechanical properties of the material.

[0009] Preferably, the thickness of the Ti3SiC2 interface layer is 200-800 nm; the holding time of the heat treatment is 30-90 min. This thickness range can provide effective interface protection and stress buffering without damaging the fiber properties, and the specific heat treatment regime is the key to ensuring that the Ti3SiC2 interface layer achieves full crystallization and performance optimization.

[0010] Preferably, the conditions for chemical vapor deposition of the SiC matrix are: deposition temperature of 1050–1150 °C, trichloromethylsilane as the source, deposition time of 200–400 h, and the density of the intermediate obtained after deposition is 1.80–2.20 g / cm³. The purpose of this step is to gently form a porous SiC matrix framework with a certain density and strength at a relatively low temperature, providing an ideal carrier for subsequent composite densification, while avoiding thermal damage to the fibers and interfaces.

[0011] Preferably, the slurry used for impregnation comprises SiC powder, Si3N4 powder, and at least one ceramic powder selected from HfC, ZrC, HfB2, and ZrB2, wherein the mass ratio of SiC powder, Si3N4 powder, and the ceramic powder is 3:1:1 to 5:1:1; the slurry is an alkaline slurry with a solid content ≤5 wt%. SiC powder has good compatibility with the matrix, Si3N4 powder helps form protective oxides at high temperatures, and Hf and Zr carbides or borides are well-known ultra-high temperature ceramics; their introduction can greatly improve the matrix's resistance to ablation and oxidation. Strictly controlling the slurry solid content to ≤5 wt% ensures its excellent flowability and permeability, enabling it to fully fill the micropores in the CVD-SiC framework.

[0012] Preferably, the metal-modified precursor is a metal-modified polysilazane or polycarbosilane precursor, wherein the metal is selected from at least one of Zr, Hf, and Ta, and the content of the metal in the precursor is 1-10 wt%. Using such a single-source precursor can ensure that the metal element is uniformly distributed at the atomic / molecular scale in the matrix. The high-entropy ceramic phase (Hf, Zr, Ta)SiCN or (Hf, Zr, Ta)SiBCN formed after pyrolysis not only has a good matching coefficient of thermal expansion with SiC, but also can gradient form a variety of high-melting-point, low-oxygen-permeability oxides, providing continuous self-healing protection over a wide temperature range.

[0013] Preferably, the metal-modified precursor impregnation pyrolysis is performed using a PIP process, with a pyrolysis temperature of 900–1500°C, and the impregnation-pyrolysis (PIP) cycle is repeated 3–5 times. Through multiple cycles, the precursor solution can be gradually penetrated into the innermost pores of the material, achieving deep densification and minimizing porosity.

[0014] Preferably, after the impregnation and pyrolysis of the metal-modified precursor, the process further includes: heat-treating the resulting composite material at 1300–1800°C for 30–60 min. This high-temperature post-treatment helps to further promote the crystallization of the PIP matrix, eliminate internal stress, and stabilize the microstructure, thereby comprehensively improving the overall performance of the composite material under extreme temperatures.

[0015] Secondly, the present invention provides a ceramic matrix composite material resistant to 1500℃, which is prepared by any of the aforementioned methods and has the following structure: Fiber preforms composed of metal-doped, high-temperature-resistant silicon carbide fibers; A Ti3SiC2 interface layer covering the fiber surface of the fiber preform; and A composite matrix containing fibers that fill the pores of the fiber preform and are coated with the interface layer.

[0016] The composite matrix is ​​composed of SiC formed by chemical vapor deposition, ceramic phase introduced by slurry impregnation, and SiCN or SiBCN phase formed by the transformation of the precursor after metal modification.

[0017] Preferably, the ceramic matrix composite material has a density of 2.60–3.20 g / cm³, a tensile strength ≥223 MPa in air at 1500°C, and a creep rupture life ≥300 hours in air at 1500°C and under 100 MPa stress. These performance indicators are direct proof that the material of the present invention can meet the long-term service requirements at 1500°C, and are significantly superior to materials using ordinary third-generation fibers and traditional interface / matrix processes.

[0018] The beneficial effects of this invention include: This invention uses metal-doped high-temperature-resistant silicon carbide fiber as a reinforcement, which can withstand temperatures of over 1500℃, fundamentally breaking through the temperature resistance bottleneck of traditional SiC fiber and providing a basic guarantee for the ultra-high temperature performance of the material system.

[0019] This invention employs chemical vapor deposition combined with a specific high-temperature heat treatment process to prepare a Ti3SiC2 interface layer. This process is gentle and causes minimal damage to the fibers. The heat-treated Ti3SiC2 interface layer exhibits perfect crystallization and strong bonding with the fibers. Its unique layered structure can still effectively achieve crack deflection and energy dissipation at high temperatures, overcoming the weakness of traditional interface layers that are prone to oxidation and failure at high temperatures.

[0020] This invention employs a three-step composite densification process involving chemical vapor deposition, slurry impregnation, and metal-modified precursor PIP. This process route is logically clear and progressively advanced, not only efficiently solving the problem of high porosity and difficulty in densification of SA fiber preforms, but also improving the precise control of the matrix's thermal expansion coefficient and high-temperature oxidation / creep resistance by introducing high-entropy ceramic phases such as (Hf, Zr, Ta)SiCN / SiBCN.

[0021] Through the triple synergistic design and optimization of fibers, interfaces, and matrix, this invention ultimately yields a composite material that exhibits long-term (≥300 hours) mechanical properties and stability in an extreme oxidizing environment at 1500℃. This makes it an ideal candidate material for future high thrust-to-weight ratio aero-engines, high-efficiency gas turbines, and hot-end components of advanced nuclear energy systems, possessing significant military and economic value. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating the preparation process of a ceramic matrix composite material resistant to 1500℃ according to an embodiment of the present invention. Detailed Implementation

[0024] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0025] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The process flow of the preparation method of the ceramic matrix composite material resistant to 1500℃ provided in the embodiments of the present invention is as follows: Figure 1 As shown, the process mainly includes four steps: fiber preform preparation, interface deposition and heat treatment, matrix composite densification, and optional post-treatment. The SA-type silicon carbide fiber described in this embodiment refers to third-generation or higher silicon carbide fibers that achieve high crystallinity, near-stoichiometry, and long-term stable performance above 1500℃ by adding aluminum (Al) elements.

[0027] Example 1 This embodiment details the preparation process of the ceramic matrix composite material resistant to 1500℃ of the present invention.

[0028] See Figure 1 The preparation process includes the following steps.

[0029] S10: Preparation of fiber preforms This step uses metal-doped, high-temperature-resistant silicon carbide fibers to form a fiber preform. The specific steps are as follows: This embodiment uses SA-type silicon carbide fiber, which achieves high crystallinity by adding trace amounts of aluminum (Al). Its monofilament grain size is 30-120 nm, and the fiber bundle contains 500-1000 fibers per bundle. To facilitate subsequent weaving and reduce process damage, a sizing agent is coated on the fiber surface. Preferably, the sizing agent is at least one of epoxy resin, polyvinyl alcohol, and propylene glycol. Subsequently, the fibers are woven into a two-dimensional layup, 2.5D, or 3D4d preform using machine weaving or braiding processes. By precisely controlling the warp and weft yarn density, the fiber volume fraction of the final preform is controlled at 35%-45%. The use of Al-added SA-type silicon carbide fiber aims to overcome the temperature resistance limit (≤1400℃) of existing SiC fibers at the reinforcement level, meeting the fundamental requirement for composite materials to operate at 1500℃.

[0030] For example, in this embodiment of the invention, the grain size of the selected Al-added SA type silicon carbide fiber is 100-120nm, the fiber bundle specification is 800 fibers / bundle, a special modified epoxy resin sizing agent is coated on the fiber surface, and the above fibers are woven into a 2.5D structure preform using a two-dimensional weaving process, and the fiber volume fraction of the final preform is controlled at 40%±2%.

[0031] S20: Deposition and heat treatment of Ti3SiC2 interface layer In this step, a Ti3SiC2 interface layer is deposited on the surface of the fiber preform formed in step S10, followed by heat treatment at 1200–1500°C. The specific operation is as follows: The fiber preform obtained in step S10 is placed in a vertical chemical vapor deposition (CVD) furnace. Interface deposition is performed first: Set the furnace temperature to 10–15 °C / min. -1 The heating rate is increased to the deposition temperature of 1080-1120°C. For example, the temperature is increased to 1100°C and held at this temperature for 60 minutes to stabilize it, and then the sizing agent is removed.

[0032] Subsequently, a mixed gas consisting of trichloromethylsilane (MTS), high-purity hydrogen (H2), and high-purity argon (Ar) is introduced into the furnace. MTS serves as the silicon and carbon source, while hydrogen and argon act as dilution gases. The MTS is carried by Ar bubbles and fed into the deposition furnace. The hydrogen flow rate ranges from 40 to 50 L / min. -1 The argon flow rate ranges from 8 to 10 L / min. -1 The deposition pressure inside the furnace was controlled at 400–700 Pa, and the deposition time under these conditions was 20–25 min. Then, the deposition gas inside the furnace was replaced with nitrogen three times, and a vacuum was drawn. The deposition temperature in the furnace was controlled at 1100℃ and held at this temperature for 30 min.

[0033] Stop the MTS supply, maintain the temperature and pressure, and then introduce a mixed gas of titanium tetrachloride (TiCl4), H2, and Ar, where TiCl4 is the titanium source and hydrogen and argon are the dilution gases. The TiCl4 is fed into the deposition furnace, and the hydrogen flow rate is 10–15 L / min. -1 Argon flow rate is 20-30 L / min -1 The deposition pressure inside the furnace is controlled at 300-500 Pa, and the deposition time is 20-25 min. Titanium (Ti) element is introduced into the fiber surface to deposit a Ti3SiC2 interface layer on the fiber surface. After deposition, the thickness of the Ti3SiC2 interface layer is 200-800 nm. For example, the thickness is 500 nm.

[0034] After deposition, a heat treatment step is immediately performed: The CVD furnace is heated to 1350–1400°C at the same heating rate, for example, to 1380°C, and held at this temperature for 30–90 min, preferably 60–70 min. The atmosphere inside the furnace is maintained as flowing Ar gas. This high-temperature heat treatment process promotes solid-state diffusion and reaction of the Si, Ti, and C atomic layers deposited on the fiber surface, generating in situ a fully crystalline MAX phase interface layer with a stoichiometric ratio close to Ti3SiC2. After this treatment, the bonding strength between the interface layer and the fiber is significantly improved, and its layered crystal structure can more effectively deflect cracks and release stress through interlayer slip at high temperatures, thereby greatly improving the long-term stability of the interface in an oxidizing environment at 1500°C.

[0035] S30: Composite densification of the matrix This step involves sequentially performing chemical vapor deposition (CVD) on a SiC matrix, impregnating ceramic powder with a slurry, and impregnating a metal-modified precursor with pyrolysis on a fiber preform with a deposited Ti3SiC2 interface layer, thereby obtaining the 1500℃-resistant ceramic matrix composite material. This three-step synergistic densification process aims to address the issues of high porosity in SA fiber preforms, difficulty in densifying with a single process, and insufficient high-temperature performance of the matrix.

[0036] Step 1: Chemical Vapor Deposition (CVD) of SiC Substrate The fiber preform treated in step S20 is then subjected to CVD. Specifically, the furnace temperature is lowered to the deposition temperature of 1050–1150°C, preferably 1080–1120°C; exemplarily, the furnace temperature is stabilized at 1100°C and held at this temperature for 30–60 min. Subsequently, a mixture of trichloromethylsilane (MTS), hydrogen, and argon is introduced, wherein MTS is the silicon and carbon source, hydrogen is the reducing gas, and argon is the carrier gas, and the MTS is fed into the deposition furnace. The argon flow rate ranges from 5 to 10 L / min. -1The H2 flow rate ranges from 20 to 60 L / min. -1 The deposition pressure inside the furnace was controlled at 300–2000 Pa, and the deposition time under these conditions was 200–400 h. The purpose of this step was to construct a continuous, complete, and porous three-dimensional network framework of SiC matrix with a certain density at a relatively mild temperature. This framework not only provides the initial strength and stiffness of the composite material, but its interconnected pores also provide channels for the subsequent impregnation of the slurry and precursor. After deposition, a porous SiC composite intermediate with a density of 1.80–2.20 g / cm³ was obtained. 3 .

[0037] Step 2: Impregnating ceramic powder with slurry This step aims to introduce micron-sized functional ceramic powders into the pores of the CVD-SiC matrix framework to adjust the matrix composition, reduce porosity, and initially improve high-temperature performance.

[0038] Slurry preparation: Weigh SiC powder, Si3N4 powder, and at least one ultra-high temperature ceramic powder selected from HfC, ZrC, HfB2, and ZrB2, and mix them in a mass ratio of 3:1:1 to 5:1:1. For example, HfB2 powder is selected, and the mixing mass ratio is 3:1:1. Place the mixed powder in a grinder for grinding to obtain a mixed powder with an average particle size of 3-6 μm. Then, slowly add the powder to a pre-prepared NaOH solution and continuously stir in a high-speed mixer to finally prepare a uniform and stable slurry with a solid content ≤5 wt% and a pH value of 10-12. Controlling the solid content to ≤5 wt% is to ensure that the slurry has excellent fluidity and permeability, and can fully wet and penetrate into all the micropores of the CVD-SiC framework; the addition of Si3N4 helps to form a low-viscosity SiO2-based protective layer at high temperatures, while the introduction of HfB2 powder brings excellent ultra-high temperature ablation resistance and oxidation resistance potential to the matrix.

[0039] Impregnation Process: The porous intermediate obtained by CVD is placed in a high-pressure impregnation tank. First, the impregnation tank is evacuated to ≤300Pa (e.g., 250Pa) and maintained for 1 hour to remove as much gas as possible from the pores of the preform. Then, the above slurry is drawn into the impregnation tank under vacuum until the sample is completely submerged. The vacuum valve is closed, and high-purity nitrogen is introduced into the tank and pressurized to 2-5MPa (e.g., 4MPa), maintaining the pressure for 2-3 hours. This pressure forces the slurry to penetrate all pores. After the pressure is maintained, the pressure is slowly released, the intermediate is removed, and dried, such as by placing it in a 120℃ oven for 12 hours to remove moisture. This vacuum-pressurized impregnation-drying process is repeated 3-5 times to ensure the filling effect.

[0040] Step 3: Metal Modification Precursor Impregnation and Pyrolysis (PIP) This step is crucial for ultimately achieving deep densification and imparting special properties to the matrix, and specifically includes: Precursor Preparation: In this embodiment, an in-situ incorporation method is used to prepare metal-modified polysilazane precursors (such as Zr-PSZ, Hf-PSZ, Ta-PSZ) or polycarbosilane precursors (such as Hf-PCS, Zr-PCS, Ta-PCS). Specifically, during the preparation of polysilazane or polycarbosilane precursors, a metal element is introduced in situ. The metal is at least one of Zr, Hf, and Ta. This process can be achieved by reacting a silicon-based monomer with a metal alkoxide, a metal halide (such as ZrCl4, HfCl4, TaCl5), or an organometallic compound (such as Zr(OR)4, Hf(NR2)4, Ta(CH2Ph)5). Preferably, the amount of metal element added is 1-10 wt% of the total weight of the precursor, the reaction atmosphere is an inert protective gas (such as nitrogen, argon, etc.), magnetic stirring or mechanical stirring is used to ensure uniform mixing of the reactants, the reaction temperature is 80℃~200℃, and the reaction time is 2~12 h. After the reaction, the solvent and byproducts are removed to obtain a clear, viscous polysilazane or polycarbosilane precursor. The preferred content of the metal (Zr, Hf, or Ta) in the precursor is 1-10 wt% of the total precursor weight. In one specific embodiment, the precursor is a metal-modified polysilazane (Hf-PSZ), prepared by reacting a silicon-based monomer with a metal halide (HfCl4). The amount of metal element (Hf) added is 3 wt% of the total precursor weight. The reaction atmosphere is argon, and mechanical stirring is used to ensure uniform mixing of the reactants. The reaction temperature is 120℃~150℃, and the reaction time is 5 h. This precursor uniformly introduces the Hf element into the polymer molecular chain through chemical bonds, ensuring atomic-level uniform distribution of the metal element in the subsequent pyrolysis products and avoiding agglomeration problems that may occur with physical mixing.

[0041] In another embodiment, the metal element can be introduced into the precursor through post-modification. Specifically, the pre-synthesized polysilazane or polycarbosilane is post-modified using the aforementioned metal alkoxides, metal halides (such as ZrCl4, HfCl4, TaCl5), or organometallic compounds (such as Zr(OR)4, Hf(NR2)4, Ta(CH2Ph)5) to react with a suitable metal compound. Preferably, the amount of metal element added is 1-10 wt% of the total weight of the precursor, the reaction atmosphere is an inert protective gas (such as nitrogen, argon, etc.), magnetic stirring or mechanical stirring is used to ensure uniform mixing of the reactants, the reaction temperature is 80℃~200℃, and the reaction time is 2~12 h.

[0042] PIP process: The intermediate (SiC fiber preform), after being impregnated and fully dried with the above slurry, is impregnated in the prepared precursor slurry. Common impregnation methods include vacuum impregnation, pressure impregnation, or vacuum-assisted resin transfer molding (VARTM). Vacuum impregnation uses an impregnation pressure of 101-104 Pa and an impregnation time of 0.5-2 h; pressure impregnation uses an impregnation pressure of 0.5-8 MPa and an impregnation time of 0.5-2 h. In this embodiment, vacuum impregnation is used; the impregnation system is placed in a vacuum device and impregnated at 100 Pa for 2 hours to allow the solution to fully penetrate. After impregnation, the sample is removed, and the impregnated green body is dried to remove solvent and volatile components; drying can be carried out at room temperature, at elevated temperatures (e.g., 60-150°C), or under vacuum. Finally, the dried green body is pyrolyzed in an inert or reducing atmosphere (e.g., argon, nitrogen, hydrogen, or vacuum). Preferably, the pyrolysis temperature is controlled within the range of 900°C to 1500°C, the pyrolysis heating rate is within the range of 0.5~10°C / min, and the holding time is within the range of 1~5 hours, to prepare a metal-added (Hf, Zr, Ta)SiCN or (Hf, Zr, Ta)SiBCN matrix. For example, taking the Hf-PSZ precursor as an example, the temperature is raised to 1200°C at a heating rate of 2°C / min and held at this temperature for 2 hours to complete the ceramic transformation of the precursor. During pyrolysis, Hf-PSZ is transformed into an amorphous / nanocrystalline multiphase ceramic containing Hf, Si, C, and N, filling the residual pores between the slurry particles and the CVD-SiC framework. After the furnace temperature naturally drops to room temperature, the sample is removed to obtain the HfSiBCN matrix. The above "impregnation-pyrolysis" process constitutes a complete PIP cycle. In this embodiment, this cycle is repeated 3-5 times to achieve gradual filling of pores and gradual increase in density. Finally, a ceramic matrix composite material is obtained.

[0043] S40: Post-processing This step is optional. The PIP-densified composite material preform is placed in a high-temperature sintering furnace for heat treatment. Specifically, under a flowing argon atmosphere, the temperature is increased to 1300~1800℃ at a rate of 5℃ / min and held for 30~60min. This high-temperature heat treatment helps to promote the further crystallization of the (Hf, Si, C, N) ceramic phase formed by PIP transformation, eliminate internal stress, and improve the bonding strength between the matrix phases, thereby stabilizing the microstructure of the composite material and optimizing its high-temperature mechanical properties.

[0044] Thus, the entire preparation of the 1500℃-resistant ceramic matrix composite material was completed, ultimately obtaining a 1500℃-resistant ceramic matrix composite material with a density of 2.60–3.20 g / cm³, a tensile strength ≥223 MPa in air at 1500℃, and a creep rupture life ≥300 hours in air at 1500℃ and under 100 MPa stress. For example, taking the aforementioned HfSiBCN matrix as an example, the tested physical and mechanical properties of this material are as follows: bulk density of 2.75 g / cm³; minimum room temperature tensile strength of 284 MPa; specifically, a tensile strength of 223 MPa measured in a 1500℃ high-temperature air environment; under the harsh conditions of 1500℃ air atmosphere and continuous 100 MPa tensile stress, its creep rupture life exceeds 300 hours (no fracture at the end of the test); after exposing the material to static air at 1500℃ for 300 hours, its room temperature tensile strength retention rate is as high as 83%. These data fully demonstrate that the ceramic matrix composites prepared by the above method have excellent long-term service capability at ultra-high temperature (1500℃).

[0045] Example 2 In this embodiment, SA-type silicon carbide fibers with added Al are selected. The fiber bundle contains 800 fibers per bundle, and the silicon carbide grain size is 100-120 nm. The surface is coated with a modified epoxy resin sizing agent, and a 3D4d preform is formed by weaving. The volume fraction of the preform is 38%-42%.

[0046] Then, the subsequent steps in Example 1 were repeated, and will not be repeated here. The density of the final prepared ceramic matrix composite material was 2.70~2.85 g / cm³. 3 For example, the density is 2.82 g / cm³. 3 The material has a minimum tensile strength of 305 MPa at room temperature and a minimum proportional ultimate stress of 151 MPa; a minimum tensile strength of 233 MPa at 1500℃ and a minimum proportional ultimate stress of 131 MPa; and a strength retention rate of 84% after 300 hours in air at 1500℃. It also has a creep rupture life of ≥300 hours in air at 1500℃ and a stress of 100 MPa.

[0047] Example 3 This embodiment aims to illustrate that by using another metal-doped high-temperature-resistant silicon carbide fiber that is consistent with the core concept of this invention and following the same interface and matrix synergistic process, a composite material that meets the requirements can also be prepared.

[0048] The core process flow of this embodiment is the same as that of Embodiment 1 (see...). Figure 1 They are exactly the same, the only difference being the reinforcing fibers: In step S10, ST-type silicon carbide fiber with added Ti (titanium) is used instead of SA-type fiber. The ST-type silicon carbide fiber also has high crystallinity, and its long-term service temperature can reach 1500℃ or higher. The fiber bundle specifications, sizing agent, and 2.5D weaving process parameters are consistent with those in Example 1, and the fiber volume fraction is controlled at approximately 40%.

[0049] All process parameters for steps S20 (interface deposition and heat treatment), S30 (matrix composite densification), and S40 (post-treatment) are exactly the same as in Example 1, and will not be repeated here.

[0050] The material prepared according to the above process in this embodiment has the following key properties after testing: density is 2.70~2.85 g / cm³. 3 For example, the density is 2.80 g / cm³. 3 The minimum tensile strength at room temperature is 300 MPa; the tensile strength at 1500℃ is 225 MPa; the creep life at 1500℃ / 100MPa exceeds 300 hours; and the strength retention rate after air exposure at 1500℃ / 300h is 83%.

[0051] This embodiment demonstrates that as long as the fiber itself achieves sufficient high-temperature stability to support service at 1500℃ through metal doping (such as Al or Ti), and is systematically integrated using the specific interface strengthening and matrix composite densification process described in this embodiment of the invention, high-performance ceramic matrix composite materials resistant to 1500℃ can be prepared.

[0052] Comparative Example 1 To clearly highlight the technological advancements and synergistic effects of this invention, comparative materials were prepared. Specifically, domestically produced third-generation silicon carbide fibers were used to prepare a 2.5D preform with a volume fraction of 38%-42%. A BN interface was deposited on the surface of the silicon carbide fiber preform, followed by a CVI process and then a PIP process to generate an HfSiBCN matrix in the intermediate.

[0053] Ultimately, the density of the material was 1.80~2.20 g / cm³. 3 The minimum tensile strength at room temperature is 340 MPa, the minimum proportional limit stress is 148 MPa, the minimum tensile strength at 1500°C is 202 MPa, the minimum proportional limit stress is 105 MPa, and the creep life at 1500°C in air atmosphere with a stress of 100 MPa is 102 hours. Since the sample failed at about 110 hours, complete 300-hour data was not obtained, and its retention rate is less than 60%.

[0054] The performance comparison of the composite materials obtained in Examples 1, 2, and Comparative Example 1 is shown in Table 1 below: Table 1

[0055] The data in Table 1 show that the 1500℃-resistant ceramic matrix composites (Examples 1, 2, and 3) prepared by the method described in the embodiments of the present invention exhibit significantly superior key high-temperature properties—strength, creep retardation life, and oxidation resistance—compared to Comparative Example 1 (existing solution). This directly confirms that the combination of a series of technical features—selecting metal-doped high-temperature-resistant silicon carbide fibers, depositing and heat-treating the Ti3SiC2 interface layer, and employing a three-step composite densification process of CVD + slurry + metal-modified precursor PIP—produced an unexpected synergistic effect, jointly solving the technical problem that ceramic matrix composites cannot serve at 1500℃ for extended periods, and successfully obtaining 1500℃-resistant ceramic matrix composites with excellent performance.

[0056] In summary, through the detailed description of the specific embodiments and the comparison of performance data of the examples and comparative examples, the technical solution claimed by the present invention has been fully demonstrated to solve the technical problem of the ceramic matrix composite material's temperature resistance of less than 1500℃ pointed out in the background art, and a new composite material with excellent high-temperature mechanical properties, long-term oxidation resistance and stability has been obtained.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a ceramic matrix composite material resistant to 1500℃, characterized in that, Includes the following steps: High-temperature resistant silicon carbide fibers with metal doping are selected to form fiber preforms; A Ti3SiC2 interface layer is deposited on the fiber surface of the fiber preform, followed by heat treatment at 1200–1500 °C. The fiber preform with the Ti3SiC2 interface layer deposited and heat-treated was subjected to chemical vapor deposition of SiC matrix, slurry impregnation of ceramic powder, and metal modification precursor impregnation pyrolysis to obtain the 1500℃ resistant ceramic matrix composite material.

2. The preparation method according to claim 1, characterized in that, The metal-doped high-temperature resistant silicon carbide fiber is either an SA-type silicon carbide fiber with added Al or an ST-type silicon carbide fiber with added Ti.

3. The preparation method according to claim 2, characterized in that, The silicon carbide fiber has a grain size of 30-120 nm and a fiber bundle with 500-1000 fibers per bundle; the fiber preform has a fiber volume fraction of 35%-45%.

4. The preparation method according to claim 1, characterized in that, The thickness of the Ti3SiC2 interface layer is 200-800 nm; the heat treatment holding time is 30-90 min.

5. The preparation method according to claim 1, characterized in that, The conditions for chemical vapor deposition of the SiC substrate are as follows: deposition temperature 1050–1150℃, trichloromethylsilane as the source, deposition time 200–400 h, and the density of the intermediate obtained after deposition is 1.80–2.20 g / cm³.

6. The preparation method according to claim 1, characterized in that, The slurry used for impregnation comprises SiC powder, Si3N4 powder, and at least one ceramic powder selected from HfC, ZrC, HfB2, and ZrB2, wherein the mass ratio of SiC powder, Si3N4 powder, and the ceramic powder is 3:1:1 to 5:1:1; the slurry is an alkaline slurry with a solid content ≤5 wt%.

7. The preparation method according to claim 1, characterized in that, The metal-modified precursor is a metal-modified polysilazane or polycarbosilane precursor, wherein the metal is selected from at least one of Zr, Hf, and Ta, and the content of the metal in the precursor is 1-10 wt%. The metal modification precursor is impregnated and pyrolyzed using the PIP process, with a pyrolysis temperature of 900–1500°C, and the impregnation-pyrolysis cycle is repeated 3–5 times.

8. The preparation method according to any one of claims 1-7, characterized in that, After the metal-modified precursor is impregnated and pyrolyzed, the process further includes: heat-treating the resulting composite material at 1300–1800°C for 30–60 min.

9. A ceramic matrix composite material resistant to 1500℃, prepared by the method according to any one of claims 1-8, characterized in that, include: Fiber preforms composed of metal-doped, high-temperature-resistant silicon carbide fibers; A Ti3SiC2 interface layer covering the fiber surface of the fiber preform; and A composite matrix containing fibers that fill the pores of the fiber preform and are coated with the interface layer; The composite matrix is ​​composed of SiC formed by chemical vapor deposition, ceramic phase introduced by slurry impregnation, and SiCN or SiBCN phase formed by the transformation of the precursor after metal modification.

10. The ceramic matrix composite material according to claim 9, characterized in that, The ceramic matrix composite material has a density of 2.60–3.20 g / cm³, a tensile strength of ≥223 MPa in air at 1500°C, and a creep life of ≥300 hours in air at 1500°C and under a stress of 100 MPa.

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