Preparation method of SiC fiber toughened high-entropy silicate ceramic matrix composite resistant to water and oxygen

Abstract

The application relates to the technical field of materials, and provides a preparation method of a SiC fiber toughened high-entropy silicate ceramic matrix composite material resistant to water and oxygen, steps of which comprise the following: firstly, high-entropy rare earth silicate and SiC particles for modulus adjustment are uniformly introduced into a SiC fiber preform with an interface layer through a slurry dipping method, so that a corrosion-resistant matrix skeleton network with the high-entropy rare earth silicate as a continuous phase is constructed; subsequently, high-entropy rare earth silicate glass matched with the skeleton composition is infiltrated into the porous skeleton through an embedding method, rapid densification of the matrix is realized, and secondary heat treatment can be carried out to promote crystallization. In the application, the high-entropy rare earth silicate completely replaces the traditional continuous SiC phase as the matrix skeleton, and the glass infiltration densification is combined, so that the prepared composite material has excellent high-temperature water and oxygen corrosion resistance and good mechanical bearing capacity, and is suitable for extreme environment hot end components such as an aero-engine.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and more specifically, to a method for preparing a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material. Background Technology

[0002] SiC / SiC composites possess excellent properties such as low density, high specific strength, high temperature resistance, oxidation resistance, and creep resistance, making them internationally recognized candidate materials for hot-end components of aero-engines. However, under the high temperature, high stress, and water vapor corrosion conditions of aero-engines, SiC / SiC composites suffer complex chemical damage, leading to material failure. To improve the high-temperature water-oxygen corrosion resistance of SiC / SiC composites, rare earth compounds with excellent water-oxygen corrosion resistance are introduced into the SiC / SiC composite matrix through matrix modification. This strengthens the barrier effect of the matrix and greatly hinders the erosion of the matrix and even the fibers by water-oxygen vapor. However, existing matrix modification methods mainly involve introducing a modifying phase into porous SiC / SiC composites. The matrix of these porous SiC / SiC composites is composed of a continuous SiC skeleton with a certain content. Therefore, the matrix modification process ultimately constructs a matrix composed of modified materials and continuous SiC phases. In a corrosive environment, both phases face the erosion of corrosive gases. The continuous SiC phase, as the weakest link in the matrix against water and oxygen erosion, is the first to be lost due to reaction. This provides a channel for corrosive gases to further erode the internal matrix and fibers of the composite material, greatly affecting the effect of matrix modification on improving the corrosion resistance of SiC / SiC composite materials.

[0003] Document "The impact of water and oxygen contents on the corrosionperformance of yttrium silicate modified SiC f "SiC composites under high temperature conditions." The CVI process was used to introduce the yttrium silicate phase into the SiC / SiC composite matrix. During the water-oxygen corrosion process at 1200℃, the Y2SiO5 phase was transformed into the Y2Si2O7 phase through a volume expansion reaction. This further improved the densification of the matrix and hindered the corrosion of water-oxygen vapor. After water-oxygen corrosion, the strength retention rate of the composite material reached 105%.

[0004] The literature "Preparation and properties of SiC / SiC-SiYC with excellent water-oxygen corrosion resistance" describes the introduction of Si-Y alloy into porous SiC / SiC composites via RMI (Reactive Metal Injection) process, resulting in a Si-YC matrix prepared through reaction. The modified composite exhibits a low open porosity (approximately 2.0%). Under high-temperature water-oxygen conditions, yttrium silicate, resistant to aqueous phases, forms and precipitates, improving the overall water-oxygen corrosion resistance of the composite.

[0005] The literature "Significant improvement of resistance to dry / water oxygen corrosion at medium and high temperatures of SiC / SiC composites upon matrix modification by Ca-Y-Al-Si-O microcrystalline glass" selected rare-earth silicate glass as a sealing agent to densify the matrix of porous SiC / SiC composites. The modified composite material has fewer defects, with an open porosity of only 1%, and the SiC fibers are not significantly corroded by the glass. After corrosion in a water-oxygen environment at 1300 °C for 100 h, the strength of the modified composite material still remains at 90% due to the excellent water corrosion resistance of yttrium silicate and mullite in the YAS glass-ceramic matrix.

[0006] Patent No. 202410315852.3 discloses a ceramic matrix composite material modified with multiphase oxide ceramics and its preparation method. High-entropy rare-earth disilicate powders are introduced into the ceramic matrix composite material via slurry impregnation and glass melt infiltration methods, and then sealed with high-entropy rare-earth silicate glass. The modified composite material has a density of 2.7-3 g / cm³. 3 It has a high density and a flexural strength of 789 MPa.

[0007] In summary, the introduction of rare earth elements into the matrix material can significantly enhance the corrosion resistance of composite materials in water-oxygen environments. However, in these modified matrices, the continuous SiC phase remains the main framework. Upon contact with high-temperature water-oxygen vapor, the reaction loss of the continuous SiC phase leads to defects in the matrix, providing channels for further corrosion of the fibers and interfaces by water vapor. To further break through the service life limit of SiC fiber-toughened composite materials in high-temperature hot-end components, this patent innovatively designs the matrix, preparing a novel high-entropy rare earth silicate ceramic matrix on a SiC fiber preform. This effectively leverages its environmental barrier function, further enhancing the corrosion resistance of the composite material in high-temperature water-oxygen environments. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material, the preparation method specifically including the following steps: Step S1: Preform preparation: A porous fiber preform is obtained using SiC fiber as raw material by a preform weaving method. Step S2: Preparation of the interface layer: An interface layer is prepared on the porous fiber preform obtained in step S1 using a chemical vapor infiltration method. Step S3: Preparation of ceramic slurry: Ceramic slurry is prepared using high-entropy rare earth silicates and SiC particles as raw materials; Step S4: Introduce ceramic slurry: Using the slurry impregnation method, introduce the ceramic slurry prepared in step S3 onto the porous fiber preform with the interface layer obtained in step S2, and then perform drying treatment to obtain the preform. Step S5: Preparation of glass powder: Glass blocks are prepared by rapid cooling and then ball milled to obtain glass powder. Step S6, Melting and Densification: Using the embedding method, the preform obtained in step S4 is embedded in glass powder, and the glass phase is introduced into the interior of the preform to obtain a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material.

[0009] Compared with existing technologies, this invention fundamentally solves the bottleneck problem of the continuous SiC matrix in traditional SiC / SiC composites being susceptible to water and oxygen corrosion through a synergistic process design of "skeleton construction-melt infiltration densification". This scheme first uses a slurry impregnation method to introduce high-entropy rare-earth silicates and SiC particles into the SiC fiber preform, constructing a matrix skeleton network with corrosion-resistant high-entropy silicates as the continuous phase and SiC particles as the tuning phase. This successfully replaces the easily corroded continuous SiC matrix with a continuous high-entropy rare-earth silicate matrix that has excellent environmental barrier effects. Subsequently, by melt infiltrating component-matched high-entropy rare-earth silicate glass into this porous skeleton, rapid densification of the matrix is ​​achieved, and further crystallization strengthening is possible. This method not only gives the matrix as a whole excellent resistance to water and oxygen corrosion, but also optimizes the modulus matching between the matrix and fibers by controlling the SiC particle content in the skeleton, thereby synergistically improving the load-bearing capacity and long-term service reliability of the composite material.

[0010] Specifically, this invention employs a slurry impregnation method to introduce high-entropy rare-earth silicate powder into a SiC fiber preform, constructing a continuous high-entropy rare-earth silicate framework. During the impregnation process, to address the modulus mismatch between high-entropy rare-earth silicate and SiC fibers, this invention incorporates SiC particles into the high-entropy rare-earth silicate framework, achieving compatibility between the macroscopic modulus of the matrix and the SiC fibers. Subsequently, a glass crystallization method is used to melt-infiltrate high-entropy rare-earth silicate glass at high temperature to fill the pores of the composite material, achieving matrix densification.

[0011] In one possible implementation, in step S1, the structure of the porous fiber preform is selected from one of chopped fiber felt, two-dimensional fiber cloth, and three-dimensional fiber preform.

[0012] Compared with existing technologies, this invention provides a variety of reinforcement structure options, such as chopped fiber mat, two-dimensional cloth, or three-dimensional preforms, which enables the method to flexibly adapt to the requirements of different application scenarios for material mechanical properties and complex shapes. This ensures that subsequent slurry impregnation and glass infiltration processes can be effectively carried out on a stable and porous fiber skeleton, laying a reliable foundation for constructing a continuous and uniform high-entropy rare earth silicate matrix.

[0013] In one possible implementation, the weaving method of the two-dimensional fiber cloth is selected from plain weave, twill weave, and satin weave; The weaving method of the three-dimensional fiber preform is either three-dimensional needle punching or three-dimensional four-way method.

[0014] Compared with existing technologies, this invention provides a variety of classic weaving methods (such as plain weave, twill weave, satin weave, three-dimensional needle punching, or four-way weave) as specific implementation options, ensuring that the prepared fiber preform has a controllable and stable pore structure and fiber arrangement. This provides a crucial preform structural foundation for the uniform construction of the high-entropy rare-earth silicate skeleton in the subsequent slurry impregnation process, as well as the smooth filling and densification of the glass phase in the melt infiltration stage, thereby ensuring the reliability of the final composite material performance.

[0015] In one possible implementation, in step S2, the material of the interface layer is pyrolytic carbon or boron nitride.

[0016] Compared with existing technologies, this invention selects pyrolytic carbon or boron nitride as the interface layer material. Its layered structure and moderate bonding strength provide effective stress buffering between the fiber and the novel high-entropy silicate matrix. This ensures that the composite material can achieve toughening through mechanisms such as fiber pull-out under load. Simultaneously, the interface layer exhibits good compatibility with subsequent slurry impregnation and high-temperature melting processes, guaranteeing the reliability of the material's overall mechanical properties.

[0017] In one possible implementation, in step S3, the raw material for the high-entropy rare-earth silicate is (RE1RE2RE3RE4).x Si y O z Or (RE1RE2RE3RE4RE5) x Si y O z RE1, RE2, RE3, RE4, and RE5 are all selected from one of Y, Yb, Ho, Er, Dy, Lu, Gd, and Tm, and x:y:z is 2:2:7 or 2:1:5.

[0018] Compared with existing technologies, this invention uses high-entropy rare-earth silicates composed of four or more rare-earth elements as the continuous matrix framework of the composite material. This high-entropy design, through a significant lattice distortion effect, not only endows the material with excellent thermal stability and resistance to water and oxygen corrosion, but also more effectively isolates the SiC fibers from corrosive media. Furthermore, its precise stoichiometry ensures the purity and controllability of the matrix phase structure, laying a precise chemical foundation for constructing a stable and reliable environmental barrier layer.

[0019] In one possible implementation, the preparation method of the ceramic slurry in step S3 is as follows: high-entropy rare-earth silicate and SiC particles are added to a dispersion, and a dispersant is added. The mixture is then magnetically stirred for 6-24 hours to obtain the ceramic slurry; wherein, The dispersion is selected from at least one of deionized water and anhydrous ethanol; The dispersant is selected from at least one of polyethyleneimine and carboxymethyl cellulose; The total mass ratio of the high-entropy rare earth silicate powder and SiC particles to the mass ratio of the dispersion is 1:(1-5). The mass ratio of the dispersant to the dispersion is 1:(100-300).

[0020] Compared with existing technologies, this invention ensures highly uniform and stable dispersion of high-entropy rare-earth silicates and SiC particles in the dispersion system by precisely specifying the slurry composition, ratio, and stirring time. This lays a crucial foundation for the subsequent slurry impregnation process, enabling the mixed powder to uniformly and completely penetrate into the pores of the fiber preform, thereby successfully constructing a continuous and compositionally controllable matrix framework network. This uniform framework is an ideal substrate for subsequent glass infiltration densification and is also the fundamental guarantee for ultimately achieving precise control of the matrix modulus and synergistic improvement of the mechanical and corrosion resistance properties of the composite material.

[0021] In one possible implementation, in step S3, the particle size of the SiC particles is 0.05-10 μm. This invention limits the particle size of the SiC particles to the range of 0.05-10 μm, which has the advantage of ensuring that the particles can form a stable, uniform, and well-flowing slurry with the high-entropy rare-earth silicate powder and dispersion medium, thus smoothly penetrating into the micropores of the fiber preform; and can also effectively act as a second phase dispersed within the subsequently formed continuous matrix framework, providing a key material basis for achieving precise control of the macroscopic modulus of the matrix.

[0022] In one possible implementation, the drying parameters in step S4 are as follows: temperature 50-100℃, time 1-5h.

[0023] Compared with existing technologies, this invention can effectively remove dispersants and solvents from the slurry by setting a mild drying temperature and sufficient time, ensuring that the high-entropy rare earth silicates and SiC particles introduced into the preform are solidified and formed initially into a stable skeleton network. At the same time, it avoids cracking of the slurry or damage to the fibers due to excessive temperature or excessive drying, and provides a matrix precursor with a complete structure and good bonding for subsequent glass infiltration densification.

[0024] In one possible implementation, in step S5, the raw material of the glass powder comprises the following composition: 20-55wt% RE2O3, 5-30wt% Al2O3, 25-80wt% SiO2, 0.5-8wt% B2O3, and 0-10wt% Cr2O3, wherein RE is selected from at least one of Y, Yb, Ho, Er, Dy, Lu, Gd, and Tm.

[0025] Compared with existing technologies, the glass composition designed in this invention and the high-entropy rare-earth silicate framework constructed in step S3 exhibit excellent chemical compatibility and matching melting characteristics. Its components not only ensure good flow at the melting infiltration temperature and fully fill the pores of the framework network for rapid densification, but also preferentially precipitate high-entropy rare-earth silicate crystalline phases and mullite phases consistent with the framework composition during subsequent cooling or heat treatment. This results in a highly uniform and dense continuous matrix in terms of composition and structure, greatly enhancing its environmental barrier effect, thereby synergistically improving the overall water and oxygen corrosion resistance and reliability of the composite material.

[0026] In one possible implementation, the parameters for the rapid cooling method in step S5 are as follows: the holding temperature is 1400-1700℃, and the holding time is 1-5h.

[0027] Compared with the prior art, the parameters used in this invention can ensure that the glass raw materials can be fully melted, homogenized and formed into a chemically stable amorphous state, thereby obtaining glass powder with uniform composition, consistent melting characteristics and suitable activity. This provides a key raw material guarantee for the smooth melting and infiltration of the glass phase, full filling of the matrix skeleton network and the final formation of a dense and corrosion-resistant continuous matrix in subsequent steps.

[0028] In one possible implementation, the parameters of the embedding method in step S6 are as follows: the heat preservation temperature is 1300-1500℃, the heat preservation time is 15-180min, and the cooling rate is 2-5℃ / min.

[0029] Compared with existing technologies, this invention ensures that the glass powder fully melts, flows, and completely impregnates the porous framework network of the preform by setting reasonable melting and infiltration temperatures, times, and cooling rates, thus achieving rapid densification. Simultaneously, the controllable cooling process facilitates the precipitation of stable crystalline phases from the glass phase, thereby forming a dense, uniform, and well-bonded continuous matrix, fundamentally guaranteeing the composite material's excellent resistance to water and oxygen corrosion and its structural integrity.

[0030] In one possible implementation, the method further includes step S7, secondary heat treatment: performing a secondary heat treatment at a temperature of 1100-1400℃ for 1-10 hours.

[0031] Compared with existing technologies, this invention, through a rationally designed secondary heat treatment process, can effectively promote the precipitation and growth of high-entropy rare-earth silicate and other crystalline phases in the melt-infiltrated glass phase. This significantly improves the crystallinity, thermal stability, and chemical inertness of the matrix, thereby further optimizing the microstructure of the composite material and enhancing its long-term structural stability and barrier protection capabilities in high-temperature water and oxygen environments. Attached Figure Description

[0032] Figure 1 A flowchart for the construction of a continuous high-entropy rare-earth silicate framework and matrix densification; Figure 2 High-entropy glass matrix of composite materials. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0034] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0036] This specific embodiment provides a method for preparing a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material, the preparation method specifically including the following steps: Step S1: Prefabrication: A porous fiber prefabrication is obtained using SiC fibers as raw material through a prefabrication weaving method; wherein, the structure of the porous fiber prefabrication is selected from one of chopped fiber mat, two-dimensional fiber cloth, and three-dimensional fiber prefabrication; the weaving method of the two-dimensional fiber cloth is selected from one of plain weave, twill weave, and satin weave; and the weaving method of the three-dimensional fiber prefabrication is three-dimensional needle punching or three-dimensional four-dimensional method. Step S2: Preparation of the interface layer: An interface layer is prepared on the porous fiber preform obtained in step S1 using a chemical vapor infiltration method; wherein the material of the interface layer is selected from pyrolytic carbon or boron nitride; Step S3: Preparation and introduction of ceramic slurry: A ceramic slurry is prepared using high-entropy rare-earth silicate and SiC particles as raw materials, and is introduced onto the porous fiber preform with the interface layer prepared in step S2 using a slurry impregnation method; wherein, the chemical formula of the high-entropy rare-earth silicate is (RE1RE2RE3RE4). x Si y O z Or (RE1RE2RE3RE4RE5) x Si y O z RE1, RE2, RE3, RE4, and RE5 are all selected from one of Y, Yb, Ho, Er, Dy, Lu, Gd, and Tm, and x:y:z is 2:2:7 or 2:1:5; The ceramic slurry is prepared by adding the high-entropy rare earth silicate powder and SiC particles to a dispersion, adding a dispersant, and stirring magnetically for 6-24 hours to obtain a stable slurry; wherein the dispersion is selected from at least one of deionized water and anhydrous ethanol; the dispersant is selected from at least one of polyethyleneimine and carboxymethyl cellulose; the mass ratio of the total mass of the high-entropy rare earth silicate powder and SiC particles to the mass of the dispersion is 1:1 to 1:5; and the mass ratio of the dispersant to the mass of the dispersion is 1:100 to 1:300. The SiC particles have a particle size of 0.05-10μm; after being introduced into the ceramic slurry, they are dried. The drying parameters are: temperature 50-100℃, time 1-5h. In specific operations, stirring is required during the impregnation process. The impregnation parameters are as follows: the impregnation time is 30 minutes, and after each impregnation, the composite material is placed in an oven at 75°C for 1.5 hours. The impregnation cycle is repeated 5 times.

[0037] Step S4, Melt Infiltration Densification: Using the embedding method, the preform treated in step S3 is embedded in glass powder, and the glass phase is introduced into the interior of the preform through melt infiltration to obtain a water- and oxygen-resistant SiC fiber-toughened high-entropy silicate ceramic matrix composite material. The glass powder is prepared by rapid quenching of the following components in mass percentage: 20-55 wt% RE2O3, 5-30 wt% Al2O3, 25-80 wt% SiO2, 0.5-8 wt% B2O3, and 0-10 wt% Cr2O3, wherein RE is selected from at least one of Y, Yb, Ho, Er, Dy, Lu, Gd, and Tm; The process parameters for the rapid cooling method are: holding temperature 1400-1700℃, holding time 1-5h; The process parameters for the embedding method melting infiltration are: holding temperature 1300-1500℃, holding time 15-180min, and cooling rate 2-5℃ / min.

[0038] The following description is based on specific embodiments.

[0039] Example 1 This embodiment provides a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material, which is prepared by the following method: S1. Preparation of fiber preform: Silicon carbide fibers are woven into carbon cloth using a plain weave method. After being cut to a suitable size, the cloth is layered and laid on a graphite mold. The graphite mold is clamped and fixed using graphite bolts to obtain a 2D silicon carbide fiber preform.

[0040] S2, Deposition of interface layer: CVI is used to prepare the interface layer and matrix of ceramic matrix composite material on the preform to form a porous material.

[0041] S3. Slurry preparation: Weigh 25g of high-entropy rare earth silicate powder, 5g of SiC powder, 70g of deionized water and 0.15g of CMC dispersant, wherein the particle size of the high-entropy rare earth silicate powder and SiC powder is about 5 μm, and mix and stir for 12h.

[0042] S4. Constructing the modified matrix: The composite material was impregnated in the slurry using a vacuum impregnation method, with stirring during the impregnation process. The impregnation parameters were as follows: impregnation time was 30 min, and after each impregnation, the composite material was placed in an oven at 90 ºC for 1.5 h. The impregnation cycle was repeated 5 times.

[0043] S5. Glass Melt Penetration Densification: A porous high-entropy rare-earth silicate matrix composite material and 4.6wt.%Y₂O₃-8wt.%Yb₂O₃-7.8wt.%Er₂O₃-7.6wt.%Ho₂O₃-13wt.%Al₂O₃-54wt.%SiO₂-5wt%B₂O₃ glass powder are placed in an alumina crucible covered with graphite paper and then placed in a tube furnace; the heat treatment process parameters are: 1000... o The heating rate below C is 5 o C / min, 1000 o The heating rate above C is 3 o C / min. The melting and infiltration temperature was 1550 ºC, and the holding time was 60 min. After glass melting and infiltration, a dense modified composite material was formed with an open porosity of approximately 3% and a flexural strength of 624 MPa. After corrosion in a high-temperature water-oxygen corrosion environment at 1300 ºC for 100 h, the material weight loss was approximately 1.4%, and the strength retention rate was approximately 94%.

[0044] Example 2 This embodiment provides a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material, which is prepared by the following method: S1. Preparation of fiber preform: Silicon carbide fibers are woven into carbon cloth using a plain weave method. After being cut to a suitable size, the cloth is layered and laid on a graphite mold. The graphite mold is clamped and fixed using graphite bolts to obtain a 2D silicon carbide fiber preform.

[0045] S2, Deposition of interface layer: CVI is used to prepare the interface layer and matrix of ceramic matrix composite material on the preform to form a porous material.

[0046] S3. Slurry preparation: Weigh 20g of high-entropy rare earth silicate powder, 10g of SiC powder, 70g of deionized water and 0.15g of CMC dispersant, wherein the particle size of the high-entropy rare earth silicate powder and SiC powder is about 5 μm, and mix and stir for 12h.

[0047] S4. Constructing the modified matrix: The composite material was impregnated in the slurry using a vacuum impregnation method, with stirring during the impregnation process. The impregnation parameters were as follows: impregnation time was 30 min, and after each impregnation, the composite material was placed in an oven at 90 ºC for 1.5 h. The impregnation cycle was repeated 5 times.

[0048] S5. Glass Melt Infiltration Densification: A porous high-entropy rare-earth silicate matrix composite material and 7.3 wt% Y₂O₃-12.9 wt% Yb₂O₃-12.5 wt% Er₂O₃-12.3 wt% Ho₂O₃-22 wt% Al₂O₃-28 wt% SiO₂-3 wt% B₂O₃-2 wt% Cr₂O₃ glass powder are placed in an alumina crucible covered with graphite paper and then placed in a tube furnace; the heat treatment process parameters are: 1000 o The heating rate below C is 5 o C / min, 1000 o The heating rate above C is 3 o C / min. The melting temperature was 1500 ºC, and the holding time was 60 min. After glass melting, a dense modified composite material was formed with an open porosity of approximately 1.8% and a flexural strength of 751 MPa. At 1300 o After corrosion in a high-temperature water-oxygen corrosion environment of C for 100 hours, the material weight loss rate is about 1.1%, and the strength retention rate is about 95%.

[0049] Comparative Example 1 S1. Preparation of fiber preform: Silicon carbide fibers are woven into carbon cloth using a plain weave method. After being cut to a suitable size, the cloth is layered and laid on a graphite mold. The graphite mold is clamped and fixed using graphite bolts to obtain a 2D silicon carbide fiber preform.

[0050] S2, Deposition of interface layer: CVI is used to prepare the interface layer and matrix of ceramic matrix composite material on the preform to form a porous material.

[0051] S3. Slurry preparation: Weigh 30g of high-entropy rare earth silicate powder, 0g of SiC powder, 70g of deionized water and 0.15g of CMC dispersant, wherein the particle size of the high-entropy rare earth silicate powder and SiC powder is about 5 μm, and mix and stir for 12h.

[0052] S4. Constructing the modified matrix: The composite material was impregnated in the slurry using a vacuum impregnation method, with stirring during the impregnation process. The impregnation parameters were as follows: impregnation time was 30 min, and after each impregnation, the composite material was placed in an oven at 90 ºC for 1.5 h. The impregnation cycle was repeated 5 times.

[0053] S5. Glass Melt Infiltration Densification: A porous high-entropy rare-earth silicate matrix composite material and 7.3 wt% Y₂O₃-12.9 wt% Yb₂O₃-12.5 wt% Er₂O₃-12.3 wt% Ho₂O₃-22 wt% Al₂O₃-28 wt% SiO₂-3 wt% B₂O₃-2 wt% Cr₂O₃ glass powder are placed in an alumina crucible covered with graphite paper and then placed in a tube furnace; the heat treatment process parameters are: 1000 o The heating rate below C is 5 o C / min, 1000 o The heating rate above C is 3 o C / min. The melting and infiltration temperature was 1500 ºC, and the holding time was 60 min. After glass melting and infiltration, a dense modified composite material was formed with an open porosity of approximately 4.2% and a flexural strength of 548 MPa. After corrosion in a high-temperature water-oxygen corrosion environment at 1300 ºC for 100 h, the material weight loss rate was approximately 0.4%, and the strength retention rate was approximately 97%.

[0054] The preparation method of this invention, through comparison of examples and comparative examples, fully verifies the advanced nature, effectiveness, and ingenious design of its technical solution. Examples 1 and 2 successfully prepared high-density, high-performance composite materials, proving that the technical path of constructing a continuous high-entropy rare-earth silicate framework using a slurry impregnation method and densifying it through matching high-entropy rare-earth silicate glass melting is entirely feasible. The resulting material retains a high strength retention rate of over 94% after 100 hours of water-oxygen corrosion at 1300℃, with an extremely low weight loss rate. This fundamentally solves the bottleneck of the continuous SiC matrix in traditional SiC / SiC composite materials being susceptible to water-oxygen erosion, achieving its core objective as an environmental barrier material.

[0055] Comparing the results of Examples 1 and 2 with Comparative Example 1, the key role of SiC particles in the matrix skeleton is clearly revealed: as the SiC particle content increases from 0 (Comparative Example 1) to 5g (Example 1) and 10g (Example 2), the room temperature flexural strength of the composite material is significantly improved, and the porosity is also significantly improved. This directly confirms that the introduction of SiC particles can effectively control the macroscopic modulus of the matrix skeleton, optimize its matching with SiC fibers, and thus synergistically improve the mechanical properties and load-bearing capacity of the composite material.

[0056] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for preparing a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material, characterized in that, The preparation method specifically includes the following steps: Step S1: Preform preparation: A porous fiber preform is obtained using SiC fiber as raw material by a preform weaving method. Step S2: Preparation of the interface layer: An interface layer is prepared on the porous fiber preform obtained in step S1 using a chemical vapor infiltration method. Step S3: Preparation of ceramic slurry: Ceramic slurry is prepared using high-entropy rare earth silicates and SiC particles as raw materials; Step S4: Introduce ceramic slurry: Using the slurry impregnation method, introduce the ceramic slurry prepared in step S3 onto the porous fiber preform with the interface layer obtained in step S2, and then perform drying treatment to obtain the preform. Step S5: Preparation of glass powder: Glass blocks are prepared by rapid cooling and then ball milled to obtain glass powder. Step S6, Melting and Densification: Using the embedding method, the preform obtained in step S4 is embedded in glass powder, and the glass phase is introduced into the interior of the preform to obtain a water- and oxygen-resistant SiC fiber-reinforced high-entropy silicate ceramic matrix composite material.

2. The preparation method according to claim 1, characterized in that, In step S1, the structure of the porous fiber preform is selected from one of chopped fiber felt, two-dimensional fiber cloth, and three-dimensional fiber preform.

3. The preparation method according to claim 2, characterized in that, The weaving method of the two-dimensional fiber cloth is selected from one of plain weave, twill weave, and satin weave; The weaving method of the three-dimensional fiber preform is either three-dimensional needle punching or three-dimensional four-way method.

4. The preparation method according to claim 1, characterized in that, In step S2, the material of the interface layer is pyrolytic carbon or boron nitride.

5. The preparation method according to claim 1, characterized in that, In step S3, the raw material for high-entropy rare earth silicate is (RE1RE2RE3RE4). x Si y O z Or (RE1RE2RE3RE4RE5) x Si y O z RE1, RE2, RE3, RE4, and RE5 are all selected from one of Y, Yb, Ho, Er, Dy, Lu, Gd, and Tm, and x:y:z is 2:2:7 or 2:1:

5.

6. The preparation method according to claim 1, characterized in that, The preparation method of the ceramic slurry in step S3 is as follows: high-entropy rare earth silicate and SiC particles are added to a dispersion, and a dispersant is added. The mixture is then magnetically stirred for 6-24 hours to obtain the ceramic slurry; wherein, The dispersion is selected from at least one of deionized water and anhydrous ethanol; The dispersant is selected from at least one of polyethyleneimine and carboxymethyl cellulose; The total mass ratio of the high-entropy rare earth silicate powder and SiC particles to the mass ratio of the dispersion is 1:(1-5). The mass ratio of the dispersant to the dispersion is 1:(100-300).

7. The preparation method according to claim 1, characterized in that, In step S3, the particle size of the SiC particles is 0.05-10 μm; and / or, In step S4, the drying parameters are as follows: temperature is 50-100℃, and time is 1-5h.

8. The preparation method according to claim 1, characterized in that, In step S5, the raw materials for the glass powder include the following composition: 20-55wt% RE2O3, 5-30wt% Al2O3, 25-80wt% SiO2, 0.5-8wt% B2O3, and 0-10wt% Cr2O3, wherein RE is selected from at least one of Y, Yb, Ho, Er, Dy, Lu, Gd, and Tm.

9. The preparation method according to claim 1, characterized in that, In step S5, the parameters for the rapid cooling method are as follows: the holding temperature is 1400-1700℃, and the holding time is 1-5 hours; and / or, In step S6, the parameters for the embedding method are as follows: the heat preservation temperature is 1300-1500℃, the heat preservation time is 15-180min, and the cooling rate is 2-5℃ / min.

10. The preparation method according to claim 1, characterized in that, It also includes step S7, secondary heat treatment: a secondary heat treatment is performed at a temperature of 1100-1400℃ for 1-10 hours.

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