A matrix-modified si c / si c composite material and a method for preparing the same

Abstract

The application relates to a matrix-modified SiC / SiC composite material and a preparation method thereof. The method comprises the following steps: depositing SiC on the surface of B4C powder through a chemical vapor deposition method to obtain core-shell structure powder; performing argon ion bombardment on the core-shell structure powder in a vacuum environment; uniformly dispersing the bombarded core-shell structure powder in an ammonium polyacrylate dispersant to obtain a modified liquid; using the modified liquid to perform multiple pressure impregnations on a SiC fiber preform with an interface layer; and performing high-temperature treatment to obtain a modified SiC fiber preform; using liquid polycarbosilane to perform multiple rounds of impregnation, solidification and cracking on the modified SiC fiber preform; and performing high-temperature sintering in an inert atmosphere to prepare the matrix-modified SiC / SiC composite material. The application effectively improves the toughness and mechanical properties of the SiC / SiC composite material, and the prepared material has excellent high-temperature resistance, oxidation resistance and reusability.

Description

Technical Field

[0001] This invention belongs to the field of aerospace materials technology, and particularly relates to a matrix-modified SiC / SiC composite material and its preparation method. Background Technology

[0002] The structural components of aerospace vehicles place increasingly higher demands on the strength, toughness, high-temperature resistance, oxidation resistance, and reusability of SiC / SiC composites. Traditional SiC / SiC composites relying solely on the SiC matrix are insufficient to meet these requirements, necessitating boron modification of the SiC matrix to enhance its reusability. However, conventional matrix boron modification methods often offer limited improvements in mechanical properties and reusability. Therefore, there is an urgent need to develop a preparation method that can comprehensively and effectively enhance the mechanical properties, high-temperature resistance, oxidation resistance, and / or reusability of SiC / SiC composites.

[0003] In summary, it is essential to provide a matrix-modified SiC / SiC composite material and its preparation method. Summary of the Invention

[0004] To address one or more technical problems existing in the prior art, the present invention provides a matrix-modified SiC / SiC composite material and its preparation method.

[0005] The present invention provides a method for preparing a matrix-modified SiC / SiC composite material in a first aspect, the method comprising the following steps:

[0006] (1) A SiC layer was deposited on the surface of B4C powder by chemical vapor deposition to obtain core-shell structured powder;

[0007] (2) The core-shell structured powder was bombarded with argon ions in a vacuum environment, and then the bombarded core-shell structured powder was added to ammonium polyacrylate dispersant and dispersed evenly to obtain a modified liquid.

[0008] (3) The SiC fiber preform with the interface layer is subjected to multiple pressure impregnations with the modified liquid and then subjected to high temperature treatment to obtain the modified SiC fiber preform.

[0009] (4) The modified SiC fiber preform was impregnated, cured and pyrolyzed in multiple rounds using liquid polycarbosilane precursor, and then sintered at high temperature in an inert atmosphere to obtain matrix-modified SiC / SiC composite material.

[0010] Preferably, the particle size of the B4C powder is 500 nm to 1 μm, and the thickness of the SiC layer is 250 nm to 500 nm.

[0011] Preferably, when bombarded by argon ions in a vacuum environment, the vacuum pressure is 10.-5 Below mbar, the voltage during the bombardment process is 1.0–2.0 keV, the current is 3–9 mA, and the bombardment duration is 5–15 min.

[0012] Preferably, the modified liquid contains 50-70 vol.% ammonium polyacrylate dispersant.

[0013] Preferably, in step (3), pressure impregnation is performed 5 to 10 times; preferably, the pressure of each pressure impregnation is 0.1 to 0.5 MPa, and the time of each pressure impregnation is 5 to 10 min.

[0014] Preferably, in step (3), the temperature of the high-temperature treatment is 400-600°C, more preferably 500°C, and the time of the high-temperature treatment is 0.5-2 hours.

[0015] Preferably, in step (4), 2 to 6 rounds of impregnation, curing, and pyrolysis are performed; during each round of impregnation, curing, and pyrolysis, the impregnation is vacuum impregnation, the vacuum impregnation pressure is 100 to 500 Pa, the vacuum impregnation time is 0.5 to 2 h, the curing temperature is 200 to 400 °C, the curing time is 0.5 to 1 h, the pyrolysis temperature is 900 to 1200 °C, and the pyrolysis time is 1 to 2 h.

[0016] Preferably, the high-temperature sintering temperature is 1200-1400℃, more preferably 1300℃, and the high-temperature sintering time is 0.5-1.5h.

[0017] Preferably, the SiC fiber preform with the interface layer is a SiC fiber preform with a PyC interface layer.

[0018] The present invention provides, in a second aspect, a matrix-modified SiC / SiC composite material prepared by the preparation method described in the first aspect of the present invention.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] (1) This invention improves the stability of the SiC / SiC composite matrix structure by precisely constructing the SiC / B4C core-shell structure, effectively improving the toughness of the SiC / SiC composite material; furthermore, by depositing a SiC layer on the outside of B4C particles and supplementing it with argon ion bombardment, this invention can construct channels for the release of B4C at high temperature, and the argon ion bombardment also helps the matrix sintering, which is beneficial to improving the reusability of the material and effectively improving the creep life of the SiC / SiC composite material in high temperature and high pressure air environment.

[0021] (2) The present invention combines slurry impregnation process, impregnation curing pyrolysis process and sintering process to rapidly enhance the sintering of each component in SiC / SiC composite matrix, effectively improving the mechanical properties of SiC / SiC composite material. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The present invention provides a method for preparing a matrix-modified SiC / SiC composite material in a first aspect, the method comprising the following steps:

[0024] (1) A SiC (silicon carbide) layer is deposited on the surface of B4C (boron carbide) powder by chemical vapor deposition to obtain core-shell structure powder (also referred to as SiC / B4C core-shell structure powder); the present invention does not impose specific limitations on the process conditions of chemical vapor deposition in step (1), and those skilled in the art can make conventional selections;

[0025] (2) The core-shell structure powder is bombarded with argon ions in a vacuum environment, and then the bombarded core-shell structure powder is added to the ammonium polyacrylate dispersant (ammonium polyacrylate) and dispersed evenly to obtain a modified liquid; the present invention does not specifically limit the source of the ammonium polyacrylate dispersant, and can use ammonium polyacrylate that can be purchased directly or synthesized by existing methods;

[0026] (3) The SiC fiber preform with the interface layer is subjected to multiple pressure impregnations using the modified liquid, and then subjected to high temperature treatment under an inert atmosphere to obtain the modified SiC fiber preform (which can also be referred to as the modified SiC composite material); in this step (3), the pressure impregnation is carried out so that the SiC fiber preform with the interface layer can be completely impregnated in the modified liquid.

[0027] (4) The modified SiC fiber preform is impregnated, cured and pyrolyzed multiple times using a liquid polycarbosilane precursor (i.e., liquid polycarbosilane), and then sintered at high temperature under an inert atmosphere to obtain a matrix-modified SiC / SiC composite material. The present invention does not specifically limit the liquid polycarbosilane, and can use products that can be purchased directly or products synthesized by existing methods. In this step (4), the modified SiC fiber preform can be completely impregnated in the liquid polycarbosilane precursor.

[0028] This invention enhances the stability of the SiC / SiC composite matrix structure and effectively improves the toughness of SiC / SiC composites through the precise construction of a SiC / B4C core-shell structure. This invention reveals that depositing a SiC layer on the surface of B4C powder to obtain a core-shell structure powder significantly improves the toughness, mechanical properties, and reusability of SiC / SiC composites under high-temperature and high-pressure air conditions compared to depositing a B4C layer on the surface of SiC powder. This is because when a SiC layer is deposited on the B4C surface to form a core-shell structure, the SiC layer can better buffer thermal stress, reducing cracking or spalling caused by differences in thermal expansion coefficients under high-temperature and high-pressure air conditions, thus improving the high-temperature stability and reusability of the material. When SiC covers the surface of B4C particles, the resulting core-shell structure can better stabilize the structure of B4C, preventing excessive oxidation reactions under high-temperature conditions. This core-shell structure can effectively disperse and alleviate stress, improving the overall mechanical strength and toughness of SiC / SiC composites. Furthermore, SiC and B4C have good interfacial bonding, and the outer SiC layer in the core-shell structure can effectively enhance the bonding force between particles and between particles and the matrix material. Furthermore, this invention, by depositing a SiC layer on the outside of B4C particles and supplementing it with argon ion bombardment, can construct channels for the release of B4C at high temperatures. Argon ion bombardment also aids in matrix sintering, improving the material's reusability and effectively enhancing the creep life of SiC / SiC composites under high temperature and high pressure air environments. This invention, by depositing a SiC layer on the outside of B4C particles and supplementing it with argon ion bombardment, can construct microscopic channels to facilitate the escape of B4C release products, thus improving the material's reusability at high temperatures. The SiC layer has excellent high temperature resistance and oxidation resistance; the protective layer it forms on the B4C surface can effectively reduce oxidation or decomposition reactions at high temperatures. Argon ion bombardment forms microchannels on the SiC layer, allowing the release of carbonized gases and / or other volatile products generated within B4C at high temperatures. This reduces the accumulation of internal pressure and lowers the likelihood of cracking or structural damage during thermal cycling, thereby making the material more stable in high temperature and high pressure air environments and extending its service life. This invention combines slurry impregnation, impregnation-curing-pyrolysis, and sintering processes to rapidly enhance the sintering of various components in the SiC / SiC composite matrix, effectively improving the mechanical properties of the SiC / SiC composite material.

[0029] According to some preferred embodiments, the particle size (average particle size) of the B4C powder is 500 nm to 1 μm (e.g., 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1 μm), and the thickness (average thickness) of the SiC layer is 250 nm to 500 nm (e.g., 250, 300, 350, 400, 450 or 500 nm).

[0030] According to some preferred embodiments, when bombarded by argon ions in a vacuum environment, the vacuum pressure is 10. - 5 Below mbar, the voltage during the bombardment process is 1.0 to 2.0 keV, the current is 3 to 9 mA, and the bombardment duration is 5 to 15 min. In this invention, it is preferred that the voltage during the bombardment process be controlled at 1.0–2.0 keV, the current at 3–9 mA, and the bombardment duration at 5–15 min. This facilitates the effective construction of a reasonable and stable channel for the release of B4C at high temperatures, thereby improving the overall performance of the prepared matrix-modified SiC / SiC composite material. This invention has found that if the voltage and current during the bombardment process are too high, or the bombardment time is too long, it will cause over-bombardment of the SiC layer, which will make the SiC layer too thin or even form holes, weakening its protective function. Furthermore, over-bombardment may deform the structure of the release channel, resulting in irregular or ineffective release channels at high temperatures, affecting the release function. On the other hand, if the voltage and current during the bombardment process are too low, or the bombardment duration is too short, the bombardment effect will be insufficient, which is not conducive to the formation of an effective release channel on the SiC layer. Both of these factors will affect the performance of the SiC / SiC composite material.

[0031] According to some preferred embodiments, the modified liquid contains 50 to 70 vol.% (e.g., 50, 55, 60, 65 or 70 vol.%) of ammonium polyacrylate dispersant.

[0032] According to some preferred embodiments, in step (3), pressure impregnation is performed 5 to 10 times (e.g., 5, 6, 7, 8, 9 or 10 times); preferably, the pressure of each pressure impregnation is 0.1 to 0.5 MPa (e.g., 0.1, 0.2, 0.3, 0.4 or 0.5 MPa), and the time of each pressure impregnation is 5 to 10 minutes (e.g., 5, 6, 7, 8, 9 or 10 minutes).

[0033] According to some preferred embodiments, in step (3), the temperature of the high-temperature treatment is 400 to 600°C (e.g., 400°C, 450°C, 500°C, 550°C or 600°C), preferably 500°C, and the time of the high-temperature treatment is 0.5 to 2 hours.

[0034] According to some preferred embodiments, in step (4), 2 to 6 rounds (e.g., 2, 3, 4, 5, or 6 rounds) of impregnation-curing-pyrolysis are performed; during each round of impregnation-curing-pyrolysis, the impregnation is vacuum impregnation, the vacuum impregnation pressure is 100 to 500 Pa (e.g., 100, 200, 300, 400, or 500 Pa), the vacuum impregnation time is 0.5 to 2 hours (e.g., 0.5, 1, 1.5, or 2 hours), and the curing temperature is 200 to 400°C (e.g., 200°C, 250°C, 300°C, 350°C). The curing temperature is 900-1200℃ (e.g., 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃ or 1200℃), and the pyrolysis time is 1-2h (e.g., 1, 1.5 or 2h). In this invention, the pyrolysis is carried out under an inert atmosphere and is atmospheric pressure pyrolysis.

[0035] According to some preferred embodiments, the high-temperature sintering temperature is 1200-1400℃ (e.g., 1200℃, 1250℃, 1300℃, 1350℃ or 1400℃), preferably 1300℃, and the high-temperature sintering time is 0.5-1.5h (e.g., 0.5, 1 or 1.5h); in this invention, the high-temperature sintering is carried out under normal pressure.

[0036] According to some preferred embodiments, the SiC fiber preform with the interface layer is a SiC fiber preform with a PyC interface layer; in this invention, the thickness (average thickness) of the PyC interface layer is, for example, 100-300 nm; in this invention, the SiC fiber preform is preferably a third-generation SiC fiber preform, that is, a fiber preform formed using third-generation SiC fibers; in this invention, the PyC interface layer (pyrolytic carbon interface layer) can be deposited on the surface of the SiC fiber preform by chemical vapor deposition, which is a conventional technique in the art.

[0037] In a second aspect, the present invention provides a matrix-modified SiC / SiC composite material prepared by the preparation method described in the first aspect of the present invention; the SiC / SiC composite material prepared by the present invention has excellent high temperature resistance, oxidation resistance, and reusability, and can be used for high-performance complex structural components.

[0038] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments. The present invention may have many other embodiments, and those skilled in the art can make various corresponding changes and modifications based on the present invention without departing from its spirit and essence; however, all such corresponding changes and modifications should fall within the scope of protection of the appended claims. Unless otherwise specified, the experimental methods used in the following embodiments and comparative examples are conventional methods. Unless otherwise specified, the materials, reagents, etc., used in the following embodiments and comparative examples are commercially available.

[0039] Example 1

[0040] ① Preparation of core-shell structured powder: A SiC layer was deposited on the surface of B4C powder using a chemical vapor deposition (CVD) process to form a core-shell structured powder. The B4C powder had a particle size of 500 nm, and the SiC layer thickness was 250 nm. The obtained core-shell structured powder was then bombarded with argon ions under a vacuum environment at a vacuum pressure of 10. -7 The bombardment process involved a voltage of 1.5 keV, a current of 6 mA, and a duration of 10 min, resulting in core-shell structured powder after bombardment.

[0041] ② Core-shell structure powder dispersion: The bombarded core-shell structure powder is uniformly dispersed in ammonium polyacrylate dispersant to obtain a modified liquid, wherein the volume fraction of the ammonium polyacrylate dispersant in the modified liquid is 60 vol.%; the obtained modified liquid is used to pressure impregnate a third-generation SiC fiber preform with a PyC interface layer (a PyC interface layer with a thickness of 200 nm) six times, and then the preform is subjected to high-temperature treatment at 500°C in an inert atmosphere (argon) for 1 hour to obtain a modified SiC fiber preform; wherein the pressure of each pressure impregnation is 0.3 MPa and the time of each pressure impregnation is 10 min.

[0042] ③ Impregnation, curing and pyrolysis: The modified SiC fiber preform obtained in step ② was subjected to three rounds of impregnation, curing and pyrolysis process using liquid polycarbosilane. In each round of impregnation, curing and pyrolysis process, the impregnation was carried out under vacuum with a vacuum pressure of 100 Pa and a vacuum impregnation time of 1 h. The curing temperature was 300 ℃ and the curing time was 1 h. The curing pressure was 2 MPa. The pyrolysis temperature was 1000 ℃ and the pyrolysis time was 1 h. The pyrolysis was carried out under an inert atmosphere (argon).

[0043] ④ High-temperature sintering: The composite material after impregnation, curing and pyrolysis in step ③ is subjected to high-temperature sintering in an Ar atmosphere. The high-temperature sintering temperature is 1300℃ and the high-temperature sintering time is 1h to obtain the matrix-modified SiC / SiC composite material.

[0044] The matrix-modified SiC / SiC composite material prepared in this embodiment was subjected to performance testing, and the room temperature fracture toughness was measured to be 20.9 MPa·m. 0.5 It has a room temperature flexural strength of 520 MPa and a creep life of 110 hours in an air environment of 1300℃ and 120 MPa.

[0045] Example 2

[0046] Example 2 is basically the same as Example 1, except that:

[0047] ① Preparation of core-shell structured powder: A SiC layer was deposited on the surface of B4C powder using a chemical vapor deposition (CVD) process to form a core-shell structured powder. The B4C powder had a particle size of 500 nm, and the SiC layer thickness was 250 nm. The obtained core-shell structured powder was then bombarded with argon ions under a vacuum environment at a vacuum pressure of 10. -7 The bombardment process involved a voltage of 0.5 keV, a current of 3 mA, and a duration of 3 min, resulting in core-shell structured powder after bombardment.

[0048] The matrix-modified SiC / SiC composite material prepared in this embodiment was subjected to performance testing, and the room temperature fracture toughness was measured to be 18.1 MPa·m. 0.5 The room temperature flexural strength is 460 MPa, and the creep life in an air environment of 1300℃ and 120 MPa reaches 93 hours.

[0049] Example 3

[0050] Example 3 is basically the same as Example 1, except that:

[0051] ① Preparation of core-shell structured powder: A SiC layer was deposited on the surface of B4C powder using a chemical vapor deposition (CVD) process to form a core-shell structured powder. The B4C powder had a particle size of 500 nm, and the SiC layer thickness was 250 nm. The obtained core-shell structured powder was then bombarded with argon ions under a vacuum environment at a vacuum pressure of 10. -7 The bombardment process involved a voltage of 3keV, a current of 10mA, and a duration of 20min, resulting in core-shell structured powder after bombardment.

[0052] The matrix-modified SiC / SiC composite material prepared in this embodiment was subjected to performance testing, and its room temperature fracture toughness was measured to be 15.8 MPa·m. 0.5 The room temperature flexural strength is 396 MPa, and the creep life reaches 84 hours in an air environment of 1300℃ and 120 MPa.

[0053] Comparative Example 1

[0054] ① Impregnation, curing and pyrolysis: Liquid polycarbosilane was used to impregnate, cure and pyrolyze the third-generation SiC fiber preform with a PyC interface layer (200nm thick). In each impregnation, curing and pyrolysis process, the impregnation was vacuum impregnation with a vacuum pressure of 100Pa and a vacuum impregnation time of 1h. The curing temperature was 300℃ and the curing time was 1h. The curing pressure was 2MPa. The pyrolysis temperature was 1000℃ and the pyrolysis time was 1h. The pyrolysis was carried out in an inert atmosphere (argon).

[0055] ② High-temperature sintering: The composite material after impregnation, curing and pyrolysis in step ① is subjected to high-temperature sintering in an Ar atmosphere. The high-temperature sintering temperature is 1300℃ and the high-temperature sintering time is 1h to obtain SiC / SiC composite material.

[0056] The SiC / SiC composite material prepared in this comparative example was tested for performance, and its room temperature fracture toughness was measured to be 14.4 MPa·m. 0.5 The room temperature flexural strength is 371 MPa, and the creep life in an air environment of 1300℃ and 120 MPa is 74 h.

[0057] Comparative Example 2

[0058] ① Preparation of core-shell structured powder: A SiC layer was deposited on the surface of B4C powder using a chemical vapor deposition (CVD) process to form a core-shell structured powder. The B4C powder had a particle size of 500 nm, and the SiC layer thickness was 250 nm. The obtained core-shell structured powder was then bombarded with argon ions under a vacuum environment at a vacuum pressure of 10. -7 The bombardment process involved a voltage of 1.5 keV, a current of 6 mA, and a duration of 10 min, resulting in core-shell structured powder after bombardment.

[0059] ② Core-shell structure powder dispersion: The bombarded core-shell structure powder is uniformly dispersed in ammonium polyacrylate dispersant to obtain a modified liquid, wherein the volume fraction of the ammonium polyacrylate dispersant in the modified liquid is 60 vol.%; the obtained modified liquid is used to pressure impregnate a third-generation SiC fiber preform with a PyC interface layer (200 nm thick PyC interface layer) six times, and then the preform is subjected to high-temperature treatment at 500℃ in an inert atmosphere (argon) for 1 h to obtain a modified SiC fiber preform; wherein the pressure of each pressure impregnation is 0.3 MPa and the time of each pressure impregnation is 10 min.

[0060] ③ High-temperature sintering: The modified SiC fiber preform obtained in step ② is sintered at a high temperature of 1300℃ and for 1 hour in an Ar atmosphere to obtain the composite material.

[0061] The composite material prepared in this comparative example was subjected to performance testing, and its room temperature fracture toughness was measured to be 12.3 MPa·m. 0.5 The room temperature flexural strength is 359 MPa, and the creep life in an air environment of 1300℃ and 120 MPa is 64 h.

[0062] Comparative Example 3

[0063] ① Preparation of core-shell structured powder: A SiC layer was deposited on the surface of B4C powder using a chemical vapor deposition (CVD) process to form a core-shell structured powder. The B4C powder had a particle size of 500 nm, and the SiC layer thickness was 250 nm. The obtained core-shell structured powder was then bombarded with argon ions under a vacuum environment at a vacuum pressure of 10. -7 The bombardment process involved a voltage of 1.5 keV, a current of 6 mA, and a duration of 10 min, resulting in core-shell structured powder after bombardment.

[0064] ② Core-shell structure powder dispersion: The bombarded core-shell structure powder is uniformly dispersed in ammonium polyacrylate dispersant to obtain a modified liquid, wherein the volume fraction of the ammonium polyacrylate dispersant in the modified liquid is 60 vol.%; the obtained modified liquid is used to pressure impregnate a third-generation SiC fiber preform with a PyC interface layer (200 nm thick PyC interface layer) six times, and then the preform is subjected to high-temperature treatment at 500℃ in an inert atmosphere (argon) for 1 h to obtain a modified SiC fiber preform; wherein the pressure of each pressure impregnation is 0.3 MPa and the time of each pressure impregnation is 10 min.

[0065] ③ Impregnation, curing and pyrolysis: The modified SiC fiber preform obtained in step ② was subjected to three rounds of impregnation, curing and pyrolysis process using liquid polycarbosilane. In each round of impregnation, curing and pyrolysis process, the impregnation was carried out under vacuum with a vacuum pressure of 100 Pa and a vacuum impregnation time of 1 h. The curing temperature was 300 ℃ and the curing time was 1 h. The curing pressure was 2 MPa. The pyrolysis temperature was 1000 ℃ and the pyrolysis time was 1 h. The pyrolysis was carried out under an inert atmosphere (argon) to obtain SiC / SiC composite material.

[0066] The SiC / SiC composite material prepared in this comparative example was subjected to performance testing, and its room temperature fracture toughness was measured to be 17.6 MPa·m. 0.5 The room temperature flexural strength is 423 MPa, and the creep life in an air environment of 1300℃ and 120 MPa is 89 h.

[0067] Comparative Example 4

[0068] ① Preparation of core-shell structured powder: A SiC layer is deposited on the surface of B4C powder by chemical vapor deposition to form a core-shell structured powder. The particle size of B4C powder is 500nm and the thickness of SiC layer is 250nm.

[0069] ② Core-shell structure powder dispersion: The core-shell structure powder obtained in step ① is uniformly dispersed in ammonium polyacrylate dispersant to obtain a modified liquid, wherein the volume fraction of the ammonium polyacrylate dispersant in the modified liquid is 60 vol.%; the obtained modified liquid is used to pressure impregnate a third-generation SiC fiber preform with a PyC interface layer (a PyC interface layer with a thickness of 200 nm) 6 times, and then the preform is subjected to high-temperature treatment at 500℃ in an inert atmosphere (argon) for 1 h to obtain a modified SiC fiber preform; wherein the pressure of each pressure impregnation is 0.3 MPa and the time of each pressure impregnation is 10 min.

[0070] ③ Impregnation, curing and pyrolysis: The modified SiC fiber preform obtained in step ② was subjected to three rounds of impregnation, curing and pyrolysis process using liquid polycarbosilane. In each round of impregnation, curing and pyrolysis process, the impregnation was carried out under vacuum with a vacuum pressure of 100 Pa and a vacuum impregnation time of 1 h. The curing temperature was 300 ℃ and the curing time was 1 h. The curing pressure was 2 MPa. The pyrolysis temperature was 1000 ℃ and the pyrolysis time was 1 h. The pyrolysis was carried out under an inert atmosphere (argon).

[0071] ④ High-temperature sintering: The composite material after impregnation, curing and pyrolysis in step ③ is sintered at a high temperature of 1300℃ and for 1 hour in an Ar atmosphere to obtain SiC / SiC composite material.

[0072] The SiC / SiC composite material prepared in this comparative example was subjected to performance testing, and its room temperature fracture toughness was measured to be 15.3 MPa·m. 0.5 The room temperature flexural strength is 392 MPa, and the creep life in an air environment of 1300℃ and 120 MPa is 83 h.

[0073] Comparative Example 5

[0074] Comparative Example 5 is basically the same as Example 1, except that:

[0075] ① Preparation of core-shell structured powder: A B4C layer was deposited on the surface of SiC powder using a chemical vapor deposition (CVD) process to form a core-shell structured powder. The SiC powder particle size was 500 nm, and the B4C layer thickness was 250 nm. The obtained core-shell structured powder was then bombarded with argon ions under a vacuum environment at a vacuum pressure of 10. -7 The bombardment process involved a voltage of 1.5 keV, a current of 6 mA, and a duration of 10 min, resulting in core-shell structured powder after bombardment.

[0076] The SiC / SiC composite material prepared in this comparative example was subjected to performance testing, and its room temperature fracture toughness was measured to be 15.5 MPa·m. 0.5 The room temperature flexural strength is 395 MPa, and the creep life reaches 84 hours in an air environment of 1300℃ and 120 MPa.

[0077] Comparative Example 6

[0078] ① B4C powder dispersion: B4C powder (particle size 500nm) is uniformly dispersed in ammonium polyacrylate dispersant to obtain a modified liquid, wherein the volume fraction of ammonium polyacrylate dispersant in the modified liquid is 60 vol.%; the obtained modified liquid is used to pressure impregnate a third-generation SiC fiber preform with a PyC interface layer (PyC interface layer with a thickness of 200nm) 6 times, and then the preform is subjected to high-temperature treatment at 500℃ in an inert atmosphere (argon) for 1 hour to obtain a modified SiC fiber preform; wherein the pressure of each pressure impregnation is 0.3MPa and the time of each pressure impregnation is 10min.

[0079] ② Impregnation, curing and pyrolysis: The modified SiC fiber preform obtained in step ① was subjected to three rounds of impregnation, curing and pyrolysis process using liquid polycarbosilane. In each round of impregnation, curing and pyrolysis process, the impregnation was carried out under vacuum with a vacuum pressure of 100 Pa and a vacuum impregnation time of 1 h. The curing temperature was 300 ℃ and the curing time was 1 h. The curing pressure was 2 MPa. The pyrolysis temperature was 1000 ℃ and the pyrolysis time was 1 h. The pyrolysis was carried out under an inert atmosphere (argon).

[0080] ③ High-temperature sintering: The composite material after impregnation, curing and pyrolysis in step ② is subjected to high-temperature sintering in an Ar atmosphere. The high-temperature sintering temperature is 1300℃ and the high-temperature sintering time is 1h to obtain SiC / SiC composite material.

[0081] The SiC / SiC composite material prepared in this comparative example was subjected to performance testing, and its room temperature fracture toughness was measured to be 14.6 MPa·m. 0.5 The room temperature flexural strength is 380 MPa, and the creep life reaches 76 hours in an air environment of 1300℃ and 120 MPa.

[0082] Comparative Example 7

[0083] ①SiC powder dispersion: SiC powder (particle size 500nm) is uniformly dispersed in ammonium polyacrylate dispersant to obtain a modified liquid, wherein the volume fraction of ammonium polyacrylate dispersant in the modified liquid is 60 vol.%; the obtained modified liquid is used to pressure impregnate a third-generation SiC fiber preform with a PyC interface layer (PyC interface layer with a thickness of 200nm) 6 times, and then the preform is subjected to high-temperature treatment at 500℃ in an inert atmosphere (argon) for 1 hour to obtain a modified SiC fiber preform; wherein the pressure of each pressure impregnation is 0.3MPa and the time of each pressure impregnation is 10min.

[0084] ② Impregnation, curing and pyrolysis: The modified SiC fiber preform obtained in step ① was subjected to three rounds of impregnation, curing and pyrolysis process using liquid polycarbosilane. In each round of impregnation, curing and pyrolysis process, the impregnation was carried out under vacuum with a vacuum pressure of 100 Pa and a vacuum impregnation time of 1 h. The curing temperature was 300 ℃ and the curing time was 1 h. The curing pressure was 2 MPa. The pyrolysis temperature was 1000 ℃ and the pyrolysis time was 1 h. The pyrolysis was carried out under an inert atmosphere (argon).

[0085] ③ High-temperature sintering: The composite material after impregnation, curing and pyrolysis in step ② is subjected to high-temperature sintering in an Ar atmosphere. The high-temperature sintering temperature is 1300℃ and the high-temperature sintering time is 1h to obtain SiC / SiC composite material.

[0086] The SiC / SiC composite material prepared in this comparative example was tested for performance, and its room temperature fracture toughness was measured to be 15.0 MPa·m. 0.5 The room temperature flexural strength is 388 MPa, and the creep life reaches 79 hours in an air environment of 1300℃ and 120 MPa.

[0087] Table 1: Performance test results of the materials finally obtained in each embodiment and comparative example.

[0088]

[0089] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a matrix-modified SiC / SiC composite material, characterized in that, The method includes the following steps: (1) A SiC layer is deposited on the surface of B4C powder by chemical vapor deposition to obtain a core-shell structure powder; the thickness of the SiC layer is 250 nm to 500 nm. (2) The core-shell structured powder was bombarded with argon ions in a vacuum environment, and then the bombarded core-shell structured powder was added to ammonium polyacrylate dispersant and dispersed evenly to obtain a modified liquid; the vacuum pressure during the bombardment with argon ions was 10. -5 Below mbar, the voltage during the bombardment process is 1.0~2.0keV, the current is 3~9mA, and the bombardment duration is 5~15min; (3) The SiC fiber preform with the interface layer is pressure impregnated 5 to 10 times with the modified liquid and then treated at high temperature to obtain the modified SiC fiber preform. (4) The modified SiC fiber preform is impregnated, cured and pyrolyzed for 2 to 6 rounds using liquid polycarbosilane precursor, and then sintered at high temperature under an inert atmosphere to obtain matrix-modified SiC / SiC composite material.

2. The preparation method according to claim 1, characterized in that: The particle size of the B4C powder is 500 nm to 1 μm.

3. The preparation method according to claim 1, characterized in that: The modified liquid contains 50-70 vol.% ammonium polyacrylate dispersant.

4. The preparation method according to claim 1, characterized in that: The pressure for each pressure impregnation is 0.1~0.5MPa, and the time for each pressure impregnation is 5~10min.

5. The preparation method according to claim 1, characterized in that: In step (3), the temperature of the high-temperature treatment is 400~600℃ and the time of the high-temperature treatment is 0.5~2h.

6. The preparation method according to claim 5, characterized in that: The high-temperature treatment is performed at a temperature of 500°C.

7. The preparation method according to claim 1, characterized in that: During each round of impregnation, curing, and pyrolysis, the impregnation is vacuum impregnation, the vacuum impregnation pressure is 100~500Pa, the vacuum impregnation time is 0.5~2h, the curing temperature is 200~400℃, the curing time is 0.5~1h, the pyrolysis temperature is 900~1200℃, and the pyrolysis time is 1~2h.

8. The preparation method according to claim 1, characterized in that: The high-temperature sintering temperature is 1200~1400℃, and the high-temperature sintering time is 0.5~1.5h.

9. The preparation method according to claim 8, characterized in that: The high-temperature sintering temperature is 1300℃.

10. The preparation method according to claim 1, characterized in that: The SiC fiber preform with an interface layer is a SiC fiber preform with a PyC interface layer.

11. A matrix-modified SiC / SiC composite material prepared by any one of claims 1 to 10.

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