Ultra-high temperature ceramic matrix composite and method of making

Abstract

The application discloses an ultrahigh-temperature ceramic matrix composite material and a preparation method thereof. f / C p The composite material is prepared from the carbon fiber fabric composite material by high-temperature disproportionation reaction with a molten salt reaction system. f / C p The composite material is prepared from the C f / MC p The composite material is prepared from the C f / MC p The composite material is prepared from the C f / MC-SiC ultrahigh-temperature ceramic matrix composite material. The preparation method provided by the application not only reduces the thermal chemical damage of carbon fibers in the metal infiltration process, but also solves the technical problem that the slurry infiltration ultrahigh-temperature ceramic phase is difficult to uniformly disperse in the fiber fabric, and the obtained ultrahigh-temperature ceramic matrix composite material has excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and in particular, to an ultra-high temperature ceramic matrix composite material and its preparation method. Background Technology

[0002] The development of high-speed aerospace vehicles places stringent performance requirements on high-temperature thermal structural materials, such as lightweight, high-temperature resistance, oxidation resistance, and ablation resistance. C / C and C / SiC composites are the most commonly used lightweight high-temperature thermal structural materials in the aerospace field. However, the operating temperature of C / SiC composites typically does not exceed 1650℃; and C / C composites suffer from insufficient oxidation resistance. Ultra-high temperature ceramics, represented by carbides and borides of refractory metals such as Ta, Zr, and Hf, possess excellent properties such as structural stability above 1800℃, oxidation resistance, and ablation resistance. Limited by the brittleness of the ceramic matrix, ultra-high temperature ceramic materials can only better realize their performance advantages through continuous fiber toughening. Therefore, carbon fiber-reinforced ultra-high temperature ceramic matrix composites have become essential for the future development of high-speed aerospace vehicles.

[0003] The core of the preparation technology for ultra-high temperature ceramic matrix composites lies in introducing the ultra-high temperature ceramic phase into the interior of carbon fiber fabrics. The introduction methods can be divided into gas-phase, liquid-phase, and solid-phase methods. The gas-phase method refers to the reaction deposition of ultra-high temperature ceramics within the fiber fabric through chemical vapor deposition. However, because the refractory metals corresponding to ultra-high temperature ceramics have large molar masses, the free path of the gas phase components of ultra-high temperature ceramics is very short, making it difficult for them to diffuse deeply into the fiber fabric like C or SiC matrices. Therefore, it is not possible to directly prepare ultra-high temperature ceramic matrix composites using chemical vapor deposition. Liquid-phase methods for preparing ultra-high temperature ceramic matrix composites include liquid-phase precursor impregnation pyrolysis (PIP) and liquid-phase metal infiltration reaction (RMI). The former involves impregnating a refractory metal organometallic compound precursor into carbon fiber fabric in liquid form, followed by curing and high-temperature pyrolysis to obtain an ultra-high temperature ceramic matrix. This process is repeated to obtain the ultra-high temperature ceramic matrix composite. This method has drawbacks such as high difficulty in precursor synthesis, high cost, low ceramic product yield, and difficulty in achieving material densification. The latter involves first introducing a sacrificial carbon phase into the carbon fiber fabric to obtain a C / C composite material, and then melting Zr, Hf metals or their alloy compounds at very high temperatures. The molten metal infiltrates into the C / C composite material and reacts with the sacrificial carbon phase to form an ultra-high temperature ceramic matrix. In this process, the high-temperature molten metal easily corrodes the fibers (causing thermal damage) and leaves a large amount of residue in the material, which seriously affects the mechanical properties of the material. Solid-state methods typically involve preparing ultra-high temperature ceramic powders such as ZrC, ZrB2, HfC, TaC, and TiC into a slurry, which is then introduced into carbon fiber fabrics via pressure infiltration or slurry injection. Finally, the material is densified through liquid-phase impregnation and pyrolysis of precursors such as polycarbosilane. However, the ultra-high temperature ceramic phase in this process is mainly distributed between the fiber bundles and is difficult to penetrate into the fiber fabric, thus requiring further optimization of the material's overall properties. Therefore, developing new processes for preparing ultra-high temperature ceramic matrix composites has significant engineering application implications. Summary of the Invention

[0004] This invention provides an ultra-high temperature ceramic matrix composite material and its preparation method, which reduces the thermochemical damage to carbon fibers during the metal infiltration process and solves the technical problem that the ultra-high temperature ceramic phase is difficult to uniformly disperse inside the fiber fabric during slurry impregnation.

[0005] According to one aspect of the present invention, a method for preparing an ultra-high temperature ceramic matrix composite material is provided, comprising the following steps:

[0006] Carbon fiber fabric was immersed in an organic sugar solution for a hydrothermal reaction to obtain a carbon fiber fabric composite. The carbon fiber fabric composite was then subjected to carbonization treatment to obtain C... f / C p Composite materials;

[0007] Cf / C p The composite material and molten salt reaction system undergo a high-temperature disproportionation reaction at 700–1200 °C. The molten salt reaction system includes a molten salt medium and reactants, wherein the reactants include a refractory metal M and its fluoride, and the refractory metal M includes Ta, Zr, Hf, or Ti. After the reaction, the product is separated and dried to obtain C. f / MC p Composite materials;

[0008] C f / MC p The composite material was vacuum impregnated in a SiC precursor solution, followed by pyrolysis at 1000–1600 °C. This vacuum impregnation and pyrolysis process was repeated at least twice to obtain C. f / MC-SiC ultra-high temperature ceramic matrix composite material.

[0009] Furthermore, before immersing the carbon fiber fabric in the organic sugar solution, the process further includes heating the carbon fiber fabric to 400–1000°C under vacuum conditions to remove the sizing agent from the surface of the carbon fiber fabric.

[0010] Furthermore, the organic sugar solution comprises a solution of one or more of sucrose, glucose, and fructose.

[0011] Furthermore, the concentration of the organic sugar solution is 5%-40%, and the pH value is 1-6.

[0012] Furthermore, the hydrothermal reaction temperature is 150–250°C, and the reaction time is 5–20 h.

[0013] Furthermore, the reactant has a mass percentage of 5-20% in the molten salt medium, and the fluoride of the refractory metal includes binary fluorides or multi-component fluorides.

[0014] Furthermore, the molten salt medium is a salt solution composed of two or more of NaCl, KCl, CaCl2, MgCl2, KF, and NaF.

[0015] Furthermore, the separation of the product from the solution includes: removing the product from the molten salt medium and washing it until no white precipitate is found when titrated with AgNO3 in the washing solution.

[0016] Furthermore, the SiC precursor solution is obtained by dissolving polycarbosilane in xylene.

[0017] According to another aspect of the present invention, an ultra-high temperature ceramic matrix composite material prepared by the above method is also provided, wherein the ultra-high temperature ceramic matrix composite material has a flexural strength of not less than 290 MPa.

[0018] The present invention has the following beneficial effects:

[0019] This invention uses an aqueous solution of an organic sugar source with excellent permeability to impregnate carbon fiber fabric. Uniformly dispersed carbon microspheres are obtained through hydrothermal reaction and vacuum carbonization. Ultra-high temperature ceramic matrix composite material is then obtained through low-temperature molten salt disproportionation reaction and impregnation pyrolysis process. The process is efficient, convenient and low-cost. It reduces the thermochemical damage to carbon fibers during the metal infiltration process and solves the technical problem that it is difficult to uniformly disperse the ultra-high temperature ceramic phase in the fiber fabric. The resulting material has excellent comprehensive performance.

[0020] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 C is obtained in Example 1 of this invention. f / C p SEM images of composite materials;

[0023] Figure 2 C is obtained in Example 1 of this invention. f XRD pattern of TaC-SiC ultra-high temperature ceramic matrix composite material;

[0024] Figure 3 C is obtained in Example 1 of this invention. f SEM image of TaC-SiC ultra-high temperature ceramic matrix composite material;

[0025] Figure 4 C is obtained in Example 1 of this invention. f Optical photograph of the surface of TaC-SiC ultra-high temperature ceramic matrix composite material after laser ablation. Detailed Implementation

[0026] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described in this specification are merely illustrative of the invention and are not intended to limit the invention.

[0027] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0028] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, "multiple" in "one or more" means two or more, and "more than" in "one or more" means two or more.

[0029] An embodiment of the first aspect of the present invention provides a method for preparing an ultra-high temperature ceramic matrix composite material, comprising the following steps: immersing carbon fiber fabric in an organic sugar solution for a hydrothermal reaction to obtain a carbon fiber fabric composite; and then subjecting the carbon fiber fabric composite to carbonization treatment to obtain C... f / C p Composite materials;

[0030] C f / C p The composite material and molten salt reaction system undergo a high-temperature disproportionation reaction at 700–1200℃. The molten salt reaction system includes a molten salt medium and reactants, wherein the reactants include a refractory metal M and its fluoride, and the refractory metal M includes refractory metals such as Ta, Zr, Hf, or Ti. After the reaction, the product is separated and dried to obtain C. f / MC p Composite materials;

[0031] C f / MC p The composite material was vacuum impregnated in a SiC precursor solution, followed by pyrolysis at 1000–1600 °C. This vacuum impregnation and pyrolysis process was repeated at least twice to obtain C. f / MC-SiC ultra-high temperature ceramic matrix composite material.

[0032] This invention first introduces carbon spheres with a scale of 0.2–2 micrometers into the interior of carbon fiber fabric using a hydrothermal method. Then, a molten salt disproportionation reaction is used to convert the micrometer-sized carbon spheres into refractory metal carbides. Finally, the carbon spheres are obtained through polycarbosilane precursor impregnation and pyrolysis (PIP process). f / MC-SiC (M:Zr,Hf,Ta,Ti, etc.) ultra-high temperature ceramic matrix composite material. In embodiments of the present invention, repeating the vacuum impregnation and pyrolysis steps at least twice includes repeating 2, 3, 4, 5, 6, 7, 8 or more times, without limitation.

[0033] This invention uses an aqueous solution of an organic sugar source with excellent permeability to impregnate carbon fiber fabric, and then prepares uniformly dispersed carbon microspheres through hydrothermal reaction and vacuum carbonization. The process is efficient, convenient, and low-cost. Ultra-high temperature ceramic matrix composite material is obtained through low-temperature molten salt disproportionation reaction and PIP process. On the one hand, it significantly reduces the thermochemical damage of the fiber, and on the other hand, it achieves a more uniform dispersion of the ultra-high temperature ceramic phase inside the fiber fabric, resulting in a material with superior comprehensive performance.

[0034] In embodiments of this application, before immersing the carbon fiber fabric in the organic sugar solution, the process further includes heating the carbon fiber fabric to 400–1000°C under vacuum conditions to remove the sizing agent from the surface of the carbon fiber fabric.

[0035] Sizing agent on carbon fiber surface is a polymer compound and is the final step in the carbon fiber production process. Fibers leaving the factory generally contain this sizing agent. In the embodiments of this application, if the sizing agent on the carbon fiber fabric surface is not removed, it will be carbonized during the subsequent molten salt process, affecting the uniform deposition of carbon microspheres on the fiber surface.

[0036] In the embodiments of this application, the organic sugar solution comprises a solution of one or more of sucrose, glucose, and fructose. Of course, the organic sugar solution used in the embodiments of this application can also be other organic sugar sources. Sucrose, glucose, or fructose are commonly used small-molecule organic sugar sources in industry, readily available, and inexpensive.

[0037] In the embodiments of this application, the concentration of the organic sugar solution is 5%-40%, and the pH value is 1-6. When the concentration of the organic sugar solution is below 5%, the reaction microspheres are small in size and few in number, requiring multiple growth cycles, resulting in low efficiency and a long process flow. When the concentration of the organic sugar solution is above 40%, there is an excessive supply of sugar source for nucleation and growth, making it difficult to control the morphology and size of the product. In addition, the embodiments of this application control the pH value at 1-6, which allows the number, size, and morphology of carbon microspheres to be controlled within a suitable range, enabling the reaction to proceed smoothly.

[0038] In the embodiments of this application, the hydrothermal reaction temperature is 150–250°C, and the reaction time is 5–20 hours. The reaction cannot proceed when the hydrothermal reaction temperature is below 150°C; when the temperature is above 250°C, the reaction pressure is too high, and safety issues will arise. Furthermore, a hydrothermal reaction time of 5–20 hours allows for control of the number, shape, and size of the carbon microspheres within a suitable range.

[0039] In the embodiments of this application, the reactant content in the molten salt medium is 5-20% by mass, and the fluoride of the refractory metal includes binary fluorides or multi-component fluorides. The embodiments of this application control the reactant concentration at 5-20% to facilitate control of the formation of the ultra-high temperature phase. Specifically, when the concentration is below 5%, the carbon microspheres will react incompletely, requiring multiple reactions, increasing the process length, and reducing reaction controllability; when the concentration is above 20%, the sacrificial carbon source is easily consumed completely, further reacting with the carbon fibers, eroding the fibers, and causing a decline in the overall performance of the composite material. At the same time, excessive reactants also lead to raw material waste and increased costs.

[0040] In the embodiments of this application, the molten salt medium is a salt solution composed of at least two of NaCl, KCl, CaCl2, MgCl2, KF, and NaF. Using the above-mentioned molten salt medium simplifies the reaction environment, facilitates subsequent purification and waste recycling, and the mixture of these salts forms a stable low-melting-point melt reaction medium, which is beneficial for the disproportionation reaction.

[0041] In the embodiments of this application, the separation of the product from the solution includes: removing the product from the molten salt medium and then washing it until no white precipitate is found when titrated with AgNO3 in the washing solution.

[0042] In embodiments of this application, the SiC precursor solution is obtained by dissolving polycarbosilane in xylene.

[0043] An embodiment of the second aspect of the present invention provides an ultra-high temperature ceramic matrix composite material prepared by the above method, wherein the ultra-high temperature ceramic matrix composite material has a flexural strength of not less than 290 MPa.

[0044] In the embodiments of this application, the density of the ultra-high temperature ceramic matrix composite material is 2.35–2.80 g / cm³. 3 .

[0045] In some embodiments, the preparation method of ultra-high temperature ceramic matrix composite material includes the following steps:

[0046] C f / C pPreparation of composite materials: (1) Place the three-dimensional carbon fiber fabric in a vacuum furnace for vacuum heat treatment to remove the sizing agent on the fiber surface. The vacuum treatment temperature is 400-1000℃. (2) Dissolve organic sugar in deionized water and add hydrochloric acid to adjust the pH value of the solution. The organic sugar can be one or more of sucrose, glucose, fructose, etc. The sugar solution concentration range is 5%-40%, and the pH value adjustment range is 1-6. (3) Soak the degummed fiber fabric in the sugar solution and then place it in a hydrothermal reactor to carry out the hydrothermal reaction. The reaction temperature is controlled at 150-250℃, and the reaction time is controlled at 5-20h. (4) Carbonize the carbon fiber fabric after hydrothermal treatment of the sugar solution under argon protection at 600-1000℃ to obtain C f / Cp composite material, in which carbon microspheres are uniformly distributed within the three-dimensional carbon fiber fabric, with a size of 0.5 to 5 micrometers.

[0047] C f / MC p Preparation of (M:Zr,Hf,Ta, etc.) composite materials: (1) Using a mixed salt of NaCl and KCl as the molten salt medium, and refractory metal powder and metal fluoride as reactants, the molten salt reaction system is obtained by ball milling. The refractory metal can be one of Ta, Zr, Hf, etc., and the metal fluoride can be a binary fluoride such as tantalum fluoride, zirconium fluoride, hafnium fluoride, or a polyfluoride such as fluorotantalate, fluorozirconate, hafnium fluoride; the mass content of the reactants in the molten salt is 5-20%; (2) The carbon fiber fabric containing carbon microspheres prepared is placed together with the molten salt reaction system in a graphite crucible and subjected to a high-temperature disproportionation reaction in an inert environment. The reaction temperature is controlled at 700-1200℃ and the reaction time is controlled at 1-5h. (3) After the reaction is complete, the sample is cooled to room temperature in the furnace. The fiber fabric is removed from the molten salt and washed with deionized water to remove residual molten salt until no white precipitate is obtained when the aqueous solution is titrated with AgNO3. Finally, it is dried in an oven to obtain C. f / MC p (M:Zr, Hf, Ta, etc.) composite materials, ultra-high temperature carbide microspheres are uniformly distributed in the three-dimensional carbon fiber fabric, especially in the fiber bundle.

[0048] C f Preparation of / MC-SiC ultra-high temperature ceramic matrix composite material: Polycarbosilane (PCS) was dissolved in xylene at a mass ratio of 1:1 to prepare a SiC precursor solution. (2) C was vacuum impregnated with the SiC precursor solution. f / MC p (M:Zr,Hf,Ta, etc.) composite materials, impregnated and then subjected to high-temperature pyrolysis, the above impregnation-pyrolysis process is repeated to obtain C. f / MC-SiC ultra-high temperature ceramic matrix composite material, the number of impregnation-pyrolysis cycles was set to 3-8 times, and the pyrolysis temperature was set to 1000-1600℃. The obtained C f The MC-SiC ultra-high temperature ceramic matrix composite material has a carbon fiber volume fraction of 30–55%, an MC ultra-high temperature ceramic phase volume fraction of 15–30%, a SiC ceramic phase volume fraction of 15–30%, a porosity of approximately 10–15%, and a density of 2.5–4.0 g / cm³. 3 .

[0049] Example

[0050] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0051] Example 1

[0052] This embodiment provides a C f The preparation method of TaC-SiC ultra-high temperature ceramic matrix composite material includes the following steps:

[0053] 1.C f / C p Preparation of composite materials

[0054] (1) The carbon fiber three-dimensional fabric is placed in a vacuum furnace for vacuum heat treatment to remove the sizing agent on the fiber surface. The vacuum treatment temperature is 400℃.

[0055] (2) Dissolve sucrose in deionized water to a sugar concentration of 10%, and adjust the pH of the solution to 3 with hydrochloric acid;

[0056] (3) Soak the degummed fiber fabric in sugar solution, then place it in a hydrothermal reactor to carry out hydrothermal reaction. The reaction temperature is controlled at 200℃ and the reaction time is 5h.

[0057] (4) Carbonization of the carbon fiber fabric after hydrothermal treatment with sugar solution was carried out under argon protection at 800℃ to obtain C f / C p Composite materials, their SEM images are as follows Figure 1 As shown in the figure, the size of the carbon microspheres is approximately 2 micrometers.

[0058] 2.C f / TaC p Preparation of composite materials

[0059] (1) A mixed salt of NaCl and KCl was used as the molten salt medium, and Ta metal powder and potassium fluorotantalate were used as reactants, with a mass content of 12% in the molten salt.

[0060] (2) The carbon fiber fabric containing carbon microspheres was prepared and placed together with the molten salt reaction system in a graphite crucible, and a high-temperature disproportionation reaction was carried out in an inert environment. The reaction temperature was controlled at 1000℃ and the reaction time was controlled at 1h. The reaction process is as follows: Ta + K2TaF7 + C → TaC + 2KF + TaF5;

[0061] (3) After the reaction is complete, the sample is cooled to room temperature in the furnace. The fiber fabric is removed from the molten salt and washed with deionized water to remove residual molten salt until no white precipitate is obtained when the aqueous solution is titrated with AgNO3. Finally, it is dried in an oven to obtain C. f / TaCp composite material, Figure 2 The obtained C f / TaC p XRD pattern of ultra-high temperature ceramic matrix composite material, showing C fibers and TaC. p The diffraction peaks of the phase indicate that the disproportionation reaction yields TaC. p Ultra-high temperature phase.

[0062] 3.C f Preparation of TaC-SiC Ultra-High Temperature Ceramic Matrix Composites

[0063] (1) Dissolve polycarbosilane (PCS) in xylene at a mass ratio of 1:1 to prepare a SiC precursor solution;

[0064] (2) Vacuum impregnation of C with SiC precursor solution f / TaCp composite material was impregnated and then subjected to high-temperature pyrolysis. This impregnation-pyrolysis process was repeated three times, with the pyrolysis temperature set at 1200℃, to obtain C. f / TaC-SiC ultra-high temperature ceramic matrix composite material. The resulting C f The density of the TaC-SiC ultra-high temperature ceramic matrix composite material, determined using Archimedes' principle and the kerosene displacement method, is 2.8 g / cm³. 3 The ultra-high temperature ceramic phase is uniformly distributed within the material (see...). Figure 3 (This is a SEM image); the material's flexural strength was determined to be 380 MPa using the three-point bending method, and was measured at 2.5 kW / cm. 2 Laser ablation for 30 seconds. Figure 4 This is an optical photograph of the material after it was ablated by a laser. As can be seen from the image, the material was almost completely ablated.

[0065] Example 2

[0066] This embodiment provides a Cf The preparation method of ZrC-SiC ultra-high temperature ceramic matrix composite material includes the following steps:

[0067] 1.C f / C p Preparation of composite materials

[0068] (1) The carbon fiber three-dimensional fabric is placed in a vacuum furnace for vacuum heat treatment to remove the sizing agent on the fiber surface. The vacuum treatment temperature is 400℃.

[0069] (2) Dissolve sucrose in deionized water to a sugar concentration of 10%, and adjust the pH of the solution to 3 with hydrochloric acid;

[0070] (3) Soak the degummed fiber fabric in sugar solution, then place it in a hydrothermal reactor to carry out hydrothermal reaction. The reaction temperature is controlled at 200℃ and the reaction time is 5h.

[0071] (4) Carbonization of the carbon fiber fabric after hydrothermal treatment with sugar solution was carried out under argon protection at 800℃ to obtain C f / C p The composite material has carbon microspheres with a size of approximately 2 micrometers.

[0072] 2.C f / ZrC p Preparation of composite materials

[0073] (1) A mixed salt of NaCl and KF was used as the molten salt medium, and Zr metal powder and potassium fluorozirconate were used as reactants, with a mass content of 20% in the molten salt.

[0074] (2) The carbon fiber fabric containing carbon microspheres was prepared and placed together with the molten salt reaction system in a graphite crucible, and a high-temperature disproportionation reaction was carried out in an inert environment. The reaction temperature was controlled at 1200℃ and the reaction time was controlled at 1h. The reaction process is as follows: Zr + K2ZrF6 + C → ZrC + 2KF + ZrF4;

[0075] (3) After the reaction is complete, the sample is cooled to room temperature in the furnace. The fiber fabric is removed from the molten salt and washed with deionized water to remove residual molten salt until no white precipitate is obtained when the aqueous solution is titrated with AgNO3. Finally, it is dried in an oven to obtain C. f / ZrC p Composite materials.

[0076] 3.C f / ZrC p Preparation of SiC Ultra-High Temperature Ceramic Matrix Composites

[0077] (1) Dissolve polycarbosilane (PCS) in xylene at a mass ratio of 1:1 to prepare a SiC precursor solution;

[0078] (2) Vacuum impregnation of C with SiC precursor solution f / ZrC p The composite material was impregnated and then subjected to high-temperature pyrolysis. This impregnation-pyrolysis process was repeated three times, with the pyrolysis temperature set at 1200℃. The resulting C f / ZrC p Based on Archimedes' principle, the density of the SiC ultra-high temperature ceramic matrix composite material was determined to be 2.75 g / cm³ using the kerosene displacement method. 3 The ultra-high temperature ceramic phase is uniformly distributed inside the material, and the bending strength of the material is approximately 260 MPa, as determined by the three-point bending method.

[0079] Example 3

[0080] This embodiment provides a C f / TiC P The preparation method of SiC ultra-high temperature ceramic matrix composite material includes the following steps:

[0081] 1.C f / C p Preparation of composite materials

[0082] (1) The carbon fiber three-dimensional fabric is placed in a vacuum furnace for vacuum heat treatment to remove the sizing agent on the fiber surface. The vacuum treatment temperature is 400℃.

[0083] (2) Dissolve glucose in deionized water to a sugar concentration of 25%, and adjust the pH of the solution to 5 with hydrochloric acid;

[0084] (3) Soak the degummed fiber fabric in a sugar solution, then place it in a hydrothermal reactor to carry out a hydrothermal reaction. The reaction temperature is controlled at 200℃ and the reaction time is 6h.

[0085] (4) Carbonization of the carbon fiber fabric after hydrothermal treatment with sugar solution was carried out under argon protection at 800℃ to obtain C f / C p The composite material has carbon microspheres with a size of approximately 2–3.5 micrometers.

[0086] 2.C f / TiC p Preparation of composite materials

[0087] (1) A mixed salt of NaCl and KCl was used as the molten salt medium, and Ti metal powder and potassium hexafluorotitanate were used as reactants, with a mass content of 10% in the molten salt.

[0088] (2) The carbon fiber fabric containing carbon microspheres was prepared and placed together with the molten salt reaction system in a graphite crucible, and a high-temperature disproportionation reaction was carried out in an inert environment. The reaction temperature was controlled at 850℃ and the reaction time was controlled at 1h. The reaction process is as follows: Ti + K2TiF6 + C → TiC + 2KF + TiF4;

[0089] (3) After the reaction is complete, the sample is cooled to room temperature in the furnace. The fiber fabric is removed from the molten salt and washed with deionized water to remove residual molten salt until no white precipitate is obtained when the aqueous solution is titrated with AgNO3. Finally, it is dried in an oven to obtain C. f / TiC p Composite materials.

[0090] 3.C f / TiC p Preparation of SiC Ultra-High Temperature Ceramic Matrix Composites

[0091] (1) Dissolve polycarbosilane (PCS) in xylene at a mass ratio of 1:1 to prepare a SiC precursor solution;

[0092] (2) Vacuum impregnation of C with SiC precursor solution f / TiC p The composite material was impregnated and then subjected to high-temperature pyrolysis. This impregnation-pyrolysis process was repeated four times, with the pyrolysis temperature set at 1200℃. The resulting C f / TiC p Based on Archimedes' principle, the density of the SiC ultra-high temperature ceramic matrix composite material was determined to be 2.35 g / cm³ using the kerosene displacement method. 3 The ultra-high temperature ceramic phase is uniformly distributed inside the material, and the bending strength of the material is 290 MPa as determined by the three-point bending method.

[0093] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing an ultra-high temperature ceramic matrix composite material, characterized in that, Includes the following steps: Carbon fiber fabric was immersed in an organic sugar solution for a hydrothermal reaction to obtain a carbon fiber fabric composite. The composite was then carbonized under argon protection at 600–1000 °C to obtain a C3 carbon fiber fabric with uniformly distributed carbon microspheres inside. f / C p Composite materials; C f / C p The composite material undergoes a high-temperature disproportionation reaction with a molten salt reaction system at 700–1200 °C. The molten salt reaction system includes a molten salt medium and reactants, wherein the reactants include a refractory metal M and its fluoride, and the refractory metal M includes Ta, Zr, Hf, or Ti. After the reaction, the product is separated and dried to obtain C-type carbon fiber bundles with ultra-high temperature carbide microspheres uniformly distributed within them. f / MC p Composite materials; C f / MC p The composite material was vacuum impregnated in a SiC precursor solution, followed by pyrolysis at 1000–1600 °C. This vacuum impregnation and pyrolysis process was repeated at least twice to obtain C. f / MC-SiC ultra-high temperature ceramic matrix composite material; The concentration of the organic sugar solution is 5%-40%, and the pH value is 1-6; The C f The carbon fiber volume fraction in the MC-SiC ultra-high temperature ceramic matrix composite material is 30-55%, the MC ultra-high temperature ceramic phase volume fraction is 15-30%, the SiC ceramic phase volume fraction is 15-30%, the porosity is 10-15%, and the density is 2.5-4.0 g / cm³. 3 .

2. The method for preparing ultra-high temperature ceramic matrix composite material according to claim 1, characterized in that, Before immersing the carbon fiber fabric in the organic sugar solution, the process also includes heating the carbon fiber fabric to 400-1000°C under vacuum conditions to remove the sizing agent from the surface of the carbon fiber fabric.

3. The method for preparing ultra-high temperature ceramic matrix composite material according to claim 1, characterized in that, The organic sugar solution includes a solution of one or more of sucrose, glucose, and fructose.

4. The method for preparing ultra-high temperature ceramic matrix composite material according to claim 1, characterized in that, The hydrothermal reaction temperature is 150~250℃, and the reaction time is 5~20h.

5. The method for preparing ultra-high temperature ceramic matrix composite material according to claim 1, characterized in that, The reactant has a mass percentage of 5-20% in the molten salt medium, and the fluoride of the refractory metal includes binary fluorides or multi-component fluorides.

6. The method for preparing ultra-high temperature ceramic matrix composite material according to claim 1, characterized in that, The molten salt medium is a salt solution composed of two or more of the following: NaCl, KCl, CaCl2, MgCl2, KF, and NaF.

7. The method for preparing ultra-high temperature ceramic matrix composite material according to claim 1, characterized in that, The separation of the product from the solution includes: removing the product from the molten salt medium and then washing it until no white precipitate is found when titrated with AgNO3 in the washing solution.

8. The method for preparing ultra-high temperature ceramic matrix composite material according to claim 1, characterized in that, The SiC precursor solution was obtained by dissolving polycarbosilane in xylene.

9. A high-temperature ceramic matrix composite material prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The bending strength of the ultra-high temperature ceramic matrix composite material is not less than 200 MPa.

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