2.5 D carbon / hafnium carbide-silicon carbide composite material as well as preparation method and application thereof

Abstract

The invention discloses a 2.5 D carbon / hafnium carbide-silicon carbide composite material and a preparation method and application thereof, and belongs to the technical field of ultra-high-temperature ceramic composites.The preparation method of the 2.5 D carbon / hafnium carbide-silicon carbide composite material comprises the following steps that a chemical vapor deposition (CVD) method, a slurry infiltration (SI) method and a precursor infiltration pyrolysis (PIP) method are coupled for use, and the 2.5 D carbon / hafnium carbide-silicon carbide composite material is obtained; the 2.5 D carbon / hafnium carbide-silicon carbide composite material is prepared; wherein HfC slurry is adopted in the slurry infiltration method, and raw materials of the HfC slurry comprise HfC particles with the particle sizes of 1 micron and 500 nm, a dispersing agent and water. According to the preparation method, chemical vapor deposition, high-solid-content slurry infiltration and precursor impregnation and pyrolysis technologies are combined, so that not only is the distribution uniformity of formed silicon carbide and hafnium carbide components ensured, but also the preparation period is effectively shortened, and the oxidation resistance and ablation resistance are obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-high temperature ceramic composite materials, and in particular relates to a 2.5D carbon / hafnium carbide-silicon carbide composite material and a preparation method and application thereof. Background Art

[0002] With the development of hypersonic vehicles, thermal protection materials are required to have excellent anti-ablation properties in oxygen-rich environments above 2000°C. Carbon fiber reinforced carbon-based composites have excellent properties such as low thermal expansion coefficient, excellent high-temperature mechanical properties and thermal shock resistance, and are a very promising material for high-temperature applications. Unfortunately, the application of C / C composites is limited to rapid oxidation and ablation in extreme environments of high-speed airflow and high temperature. At present, there are two main methods to improve the oxidation and ablation resistance of carbon-based composites. One is to cover the surface of the carbon matrix with an anti-oxidation coating; the other is to introduce an ultra-high temperature ceramic (UHTCs) phase with high temperature resistance into the carbon matrix. Among them, the introduction of ultra-high temperature ceramics (such as ZrC, ZrB 2 , HfC, HfB 2 ) is a better method. In addition, among the existing ultra-high temperature ceramic systems, the HfC-SiC system has been systematically studied due to its good ablation resistance, but the C / HfC-SiC composites prepared by different processes have different microstructures, which gives the composites different ablation resistance.

[0003] At present, according to the needs of actual industrial application fields and the specific microstructure and performance requirements of carbon / hafnium carbide-silicon carbide composites, the following preparation technologies have been developed: chemical vapor infiltration / deposition (CVI / CVD), slurry infiltration (SI), reactive melt infiltration (RMI), and precursor impregnation pyrolysis (PIP). Most of these methods have obvious disadvantages, such as long time and high cost of CVI, damage to fibers by RMI, and low ceramic conversion rate of UHTCs precursors during PIP. The SI method has a natural advantage in introducing ultra-high temperature ceramics. By preparing and impregnating simple slurries, ceramic phases can be introduced into carbon-based composites at a relatively low cost, and the whole process is very time-saving. However, ceramic slurries with low UHTCs content and high viscosity introduce ceramic phases with low volume fractions; while ceramic slurries with high solid content have high viscosity, which accumulates in the surface layer of carbon fiber preforms, resulting in uneven distribution.

[0004] To solve these problems, the traditional slurry impregnation process has been improved in recent years. Currently, the preparation of UHTCs modified carbon-based composites mainly uses one or two preparation processes in combination, and SI, a more time-saving process, is rarely used. Therefore, how to use the SI process with high solid content and low viscosity to impregnate the slurry to prepare carbon / silicon carbide-hafnium carbide composites is of great significance to the aerospace field. Summary of the invention

[0005] In view of the above technical problems, the present invention proposes a 2.5D carbon / hafnium carbide-silicon carbide composite material and a preparation method and application thereof.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention:

[0008] A method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material comprises the following steps:

[0009] The 2.5D carbon / hafnium carbide-silicon carbide composite material was prepared by coupling chemical vapor deposition (CVD)-slurry infiltration (SI)-precursor impregnation pyrolysis (PIP) method;

[0010] The slurry infiltration method uses HfC slurry, and its raw materials include HfC particles with particle sizes of 1 μm and 500 nm, a dispersant and water.

[0011] Optionally, the mass ratio of the HfC particles with a particle size of 1 μm and 500 nm is 3:7.

[0012] Optionally, the mass ratio of the HfC particles, the dispersant and the deionized water is 20-50: 0.4-0.9: 6-8, preferably: 24.4: 0.486: 8; 36.6: 0.654: 7; 48.8: 0.822: 6.

[0013] Beneficial effect: Within the above dosage ratio range defined in the present invention, the prepared HfC impregnation slurry has low viscosity, good stability, and can load more HfB 2 Granules have the advantage of being more conducive to impregnation.

[0014] Optionally, the dispersant is sodium hexametaphosphate; and the pH value of the HfC slurry is 3-11.

[0015] Optionally, the preparation method of the 2.5D carbon / hafnium carbide-silicon carbide composite material specifically comprises the following steps:

[0016] PAN-based carbon fiber is used as the matrix, and the density of needle weaving is 0.4g / cm 3 2.5D carbon fiber preform;

[0017] Using chemical vapor deposition, a layer of pyrolytic carbon is deposited on the surface of the 2.5D carbon fiber preform using methane gas to obtain a 2.5D carbon matrix;

[0018] The 2.5D carbon matrix is ​​sequentially vacuum impregnated and pressure impregnated into the HfC slurry by a slurry infiltration method, and a 2.5DC / HfC-SiC composite material blank is obtained after drying;

[0019] The precursor impregnation pyrolysis method is adopted to cyclically treat the 2.5D CHfC-SiC composite material blank in a precursor solution by impregnation, drying and pyrolysis as a cycle until the weight gain rate is less than 1%, thereby obtaining the 2.5D carbon / hafnium carbide-silicon carbide composite material.

[0020] Optionally, the conditions during chemical vapor deposition are:

[0021] Under an inert atmosphere, heat to 1150°C at a heating rate of 10°C / min, then introduce methane gas at a gas flow rate of 300mL / min for 15 to 30min, and keep at 1150°C for 15 to 30min, and then cool naturally.

[0022] Optionally, the vacuum impregnation process is:

[0023] First, the 2.5D carbon matrix is ​​placed in a beaker, and then placed in a vacuum tower, and evacuated using a vacuum pump for 15 to 30 minutes;

[0024] Then, the HfC slurry is added into the beaker until the 2.5D carbon substrate is immersed, and the vacuum degree is maintained for 15 to 30 minutes, and then naturally restored to a normal pressure state, and then dried.

[0025] Optionally, the pressure impregnation process is: completely immerse the vacuum-impregnated 2.5D carbon matrix in the HfC slurry, place it in a reactor and pressurize it to 4-5 MPa, maintain it for 4-5 hours; release the pressure to normal pressure; and then dry it.

[0026] Optionally, the precursor solution is a mixed solution of polycarbosilane and xylene in a mass ratio of 1:1.

[0027] Optionally, the drying temperature in the drying process is 150-160° C., and the drying time is 1-2 hours; and / or,

[0028] The conditions in the pyrolysis process are: heating to 700-1300° C. at a heating rate of 10° C. / min, and then pyrolyzing at this temperature for 30-60 minutes.

[0029] The second technical solution of the present invention:

[0030] A 2.5D carbon / hafnium carbide-silicon carbide composite material is prepared by the above preparation method.

[0031] The third technical solution of the present invention:

[0032] Application of the above 2.5D carbon / hafnium carbide-silicon carbide composite material in the preparation of hypersonic aircraft.

[0033] Compared with the prior art, the present invention has the following advantages and technical effects:

[0034] (1) The present invention combines the traditional CVD-SI-PIP process, uses the CVD process to generate a thin layer of pyrolytic carbon on the carbon fiber preform to protect the fiber, uses the SI process to introduce a uniform UHTCs phase, and uses the PIP process to densify the composite material. That is, the three methods of the present invention work synergistically to achieve the optimization of the process flow for preparing C / HfC-SiC composite materials and shorten the preparation cycle of the composite materials.

[0035] (2) The present invention obtains a SI process impregnated HfC slurry with high solid content and low viscosity (solid content of 20-40 vol%, viscosity of ~1 Pa·s) by optimizing the dispersant, grading and pH value of the HfC slurry in the SI process, so as to achieve the purpose of uniform dispersion in the carbon fiber matrix, thereby regulating the anti-ablation performance of the carbon / hafnium carbide-silicon carbide composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 Schematic diagram of the preparation process of the 2.5D carbon / hafnium carbide-silicon carbide composite material of the present invention;

[0038] Figure 2 Schematic diagram of the structure and preparation process of the 2.5D carbon / hafnium carbide-silicon carbide composite material of the present invention;

[0039] Figure 3 This is a SEM image of the 2.5D carbon / hafnium carbide-silicon carbide composite material prepared in Example 1;

[0040] Figure 4 This is a SEM image of the 2.5D carbon / hafnium carbide-silicon carbide composite material prepared in Example 2;

[0041] Figure 5 This is a SEM image of the 2.5D carbon / hafnium carbide-silicon carbide composite material prepared in Example 3;

[0042] Figure 6 This is a SEM image of the 2.5D carbon / silicon carbide composite material prepared in Comparative Example 1;

[0043] Figure 7The viscosity curve of the slurry prepared by different mass ratios of HfC particles with a particle size of 1 μm and 500 nm in Example 1;

[0044] Figure 8 The Zeta potential distribution curve of the slurry prepared by different types of dispersants in Example 1;

[0045] Fig. 9 This is a Zeta potential distribution curve of the slurry prepared at different pH values ​​in Example 1. DETAILED DESCRIPTION

[0046] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0047] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0048] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0049] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0050] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0051] The embodiment of the present invention discloses a method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material, comprising the following steps:

[0052] Using PAN-based carbon fiber as the matrix, needle-punching and weaving is a 2.5D carbon fiber preform;

[0053] A thin layer of pyrolytic carbon is deposited on the surface of the 2.5D carbon fiber preform using methane gas by chemical vapor deposition to obtain a 2.5D carbon matrix;

[0054] HfC particles of different sizes are uniformly dispersed in deionized water using a dispersant to obtain a HfC slurry with high solid content and low viscosity, and the 2.5D carbon matrix is ​​vacuum- and pressure-impregnated into the HfC slurry, and a C / HfC-SiC composite body is obtained after drying;

[0055] The CHfC-SiC composite material blank is immersed in a mixed solution of xylene and polycarbosilane, dried, and pyrolyzed to obtain a C / HfC-SiC composite material precursor; wherein the composite material precursor is repeatedly immersed, dried, and pyrolyzed until the weight gain rate is less than 1%, thereby obtaining the 2.5D carbon / hafnium carbide-silicon carbide composite material.

[0056] It is worth noting that the above-mentioned weight gain rate of <1% means that the mass difference before and after one cycle of the impregnation, drying and pyrolysis process is <1%, and the value of the weight gain rate will decrease as the impregnation, drying and pyrolysis processes are repeated.

[0057] In some optional embodiments, the chemical vapor deposition method includes the following steps:

[0058] The carbon fiber preform was placed in a tubular furnace and heated to 1150°C at a heating rate of 10°C / min. Ar gas was used as a protective gas at a gas flow rate of 100mL / min to protect the carbon fiber preform. Then, methane gas was introduced at a gas flow rate of 300mL / min for 15 to 30min, and the temperature was kept at 1150°C for 15 to 30min. After naturally cooling to room temperature, the Ar gas was turned off.

[0059] In some optional embodiments, the mass ratio of HfC particles with a particle size of 1 μm and 500 nm in the HfC slurry is 3:7;

[0060] The dispersant is sodium hexametaphosphate, and the pH value of the slurry is adjusted to 3-11.

[0061] In some optional embodiments, the vacuum impregnation method includes: placing the 2.5D carbon matrix into a beaker and then placing the beaker in a vacuum tower, using a vacuum pump to evacuate for 15 to 30 minutes, adding the above-mentioned HfC slurry into the beaker until the 2.5D carbon fiber preform is immersed, maintaining the vacuum for 15 to 30 minutes, and then naturally returning to normal pressure, and then drying.

[0062] In some optional embodiments, the pressure impregnation method includes: completely immersing the dried preform in the HfC slurry, placing it in a reactor and pressurizing it to 4-5 MPa for 4-5 hours; releasing the pressure to normal pressure; and then drying.

[0063] In some optional embodiments, the drying temperature is 100-110° C., and the drying time is 4-5 hours.

[0064] In some optional embodiments, the mixed solution is obtained by mixing polycarbosilane and xylene in a mass ratio of 1:1.

[0065] In some optional embodiments, the drying temperature is 150-160° C., and the drying time is 1-2 hours.

[0066] In some optional embodiments, the pyrolysis temperature is 700-1300° C., the heating rate is 10° C. / min, and the time is 30-60 min.

[0067] The invention discloses a 2.5D carbon / hafnium carbide-silicon carbide composite material, which is prepared by the above preparation method.

[0068] The present invention also discloses the application of the 2.5D carbon / hafnium carbide-silicon carbide composite material in the preparation of a hypersonic aircraft.

[0069] The anti-ablation principle of the 2.5D carbon / hafnium carbide-silicon carbide composite material prepared by the present invention for preparing hypersonic aircraft is:

[0070] Due to the high heat flux density and dynamic pressure, key thermal protection system components of hypersonic vehicles, such as nose cones, leading edges, scramjet combustion chambers and nozzles, are subject to extreme aerodynamic heating. As the flight speed increases, aerodynamic heating intensifies, causing the surface temperature to rise sharply to over 2000°C in a short period of time. In this extreme thermal environment, the good ablation resistance of the carbon / hafnium carbide-silicon carbide prepared by the present invention can support its better adaptation to extreme service environments. During the ablation process, the composite material mainly undergoes the following reactions:

[0071] 2C(s)+O 2 (g) → 2CO(g);

[0072] C(s)+O 2 (g) →CO 2 (g);

[0073] 2SiC(s)+3O 2 (g)→2SiO 2 (l) + 2CO(g);

[0074] SiC(s)+O 2(g)→SiO(g)+CO(g);

[0075] SiO 2 (l)+CO(g)→SiO(g)+CO 2 (g);

[0076] SiO 2 (l)→SiO 2 (g);

[0077] 2H 2 (s)+5O 2 (l)→2HfO 2 (s)+2B 2 O 3 (g);

[0078] At the beginning of ablation, the surface temperature of the sample rises rapidly, and the oxidizing gas reacts with the carbon fiber, while the solid SiC is oxidized into liquid SiO 2 Spread on the sample surface to prevent oxygen from further entering the matrix; as the temperature increases further, the oxidation of SiC becomes highly active, and at this time SiC and HfB 2 The evaporation of the gas produced by oxidation absorbs the heat in the flame, and the continuous HfO 2 The layer acts as a barrier to further oxidation by oxygen. 2 The composite addition of SiC can improve the ablation resistance of carbon-based composites.

[0079] Unless otherwise specified, the "room temperature" in the present invention refers to 20-30°C; "normal pressure" refers to one standard atmospheric pressure.

[0080] The raw materials used in the present invention are all purchased from the market. The reagents used in the following examples are: xylene (Sinopharm Group Chemical Reagent Co., Ltd.), sodium hexametaphosphate (Sinopharm Group Chemical Reagent Co., Ltd.), hydrochloric acid (Sinopharm Group Chemical Reagent Co., Ltd.), ammonia (Sinopharm Group Chemical Reagent Co., Ltd.); PAN-based carbon fiber was purchased from Jiangsu Tianniao High-tech Co., Ltd.; and the needle-punched weaving used in the examples is a conventional technical means in the art, which will not be described in detail here.

[0081] The technical solution of the present invention is further illustrated by the following embodiments.

[0082] Example 1

[0083] like Figure 1 As shown, a method for preparing a 2D carbon / carbon-silicon carbide composite material comprises the following steps:

[0084] S1. Needle-punch PAN-based carbon fiber to a density of 0.4 g / cm 32.5D carbon fiber preform;

[0085] S2, placing the preform in a tubular furnace, introducing Ar gas at a flow rate of 100 mL / min, and heating the preform to 1150°C at a heating rate of 10°C / min and keeping the temperature for 30 min, then introducing methane gas at a flow rate of 300 mL / min for 30 min, and cooling the preform naturally to room temperature to obtain a 2.5D carbon matrix;

[0086] S3, 7.32g HfC particles with a particle size of 1μm, 17.08g HfC particles with a particle size of 500nm, 8g deionized water, and 0.486g sodium hexametaphosphate were mixed uniformly as HfC impregnation slurry; the slurry pH was adjusted to 11 using dilute hydrochloric acid and ammonia water to obtain a high solid content and low viscosity ceramic slurry (HfC slurry, solid content of 20vol%; viscosity of 0.998Pa·s);

[0087] S4, put the 2.5D carbon matrix in step S2 into a beaker, place the beaker in a vacuum tower, use a vacuum pump to evacuate for 30 minutes, then add 200 mL of HfC slurry in step S3 into the beaker, continue to evacuate for 30 minutes, then slowly release the pressure to normal pressure, and place the green body in a 100°C oven to dry for 4 hours;

[0088] S5, placing the green body after drying in step S4 into a beaker (containing 200 mL of HfC slurry), placing the beaker in a reactor, introducing Ar gas until the pressure in the reactor reaches 5 MPa, maintaining for 5 h, then slowly releasing the pressure to normal pressure, placing the green body in a 100 ° C oven and drying for 4 h to obtain a 2.5DC / HfC-SiC composite green body;

[0089] S6, 200 g of polycarbosilane (PCS) and 200 g of xylene were mixed uniformly to obtain a precursor solution;

[0090] S7. Immerse the 2.5DC / HfC-SiC composite material body in the precursor solution, evacuate for 30 minutes, then put it into an oven and dry it at 150°C for 1 hour to complete the curing and cross-linking. Then, pyrolyze it at 1300°C in a tubular furnace for 30 minutes with a heating rate of 10°C / min. This is one cycle, and then repeat this cycle until the weight gain rate is less than 1%, thereby obtaining a 2.5D carbon / hafnium carbide-silicon carbide composite material.

[0091] The SEM image of the 2.5D carbon / HfC-SiC composite material prepared in this example is as follows: Figure 3 As shown in the figure, it can be seen that the HfB introduced by SI 2 The particles are evenly distributed in the composite material and filled between the fiber bundles. At the same time, the SiC introduced in the PIP process 2The particles are loaded and packed together between the fiber bundles, densifying the material.

[0092] In addition, based on step S3 of Example 1, the present invention adopts the controlled variable method to explore the influence of three parameters for preparing HfC slurry with high solid content and low viscosity (the three optimal parameters are: the mass ratio of HfC particles with a particle size of 1 μm and 500 nm is 3:7, the dispersant is sodium hexametaphosphate, and the pH value of the HfC slurry is 11) on the slurry performance.

[0093] 1. The total mass of HfC particles is kept constant, and the mass ratios of HfC particles with a particle size of 1 μm and 500 nm are 0:10, 3:7, 5:5, 7:3, and 10:0, respectively. Figure 7 As shown in the figure, when the mass ratio is 3:7, the slurry viscosity is the lowest and the impregnation effect is the best.

[0094] 2. Set the slurry stability without dispersant, and with sodium hexametaphosphate, polyethylene glycol, and polyethyleneimine as dispersants, such as Figure 8 As shown in the figure, when sodium hexametaphosphate is selected as the dispersant, the absolute value of the slurry Zeta potential is the largest, indicating that the slurry is the most stable. This is because the phosphate anions generated by the ionization and dissociation of sodium hexametaphosphate are characteristically adsorbed on the surface of the powder. This adsorption behavior promotes the formation of an extended double-layer structure at the interface between the particles and the solution, thus stabilizing the slurry.

[0095] 3. Set the slurry to different pH values ​​of 3, 5, 7, 9, and 11 to explore the slurry stability. Fig. 9 As shown in the figure, it is found that when the slurry pH value is 11, the absolute value of Zeta potential is the largest and the slurry is the most stable. This is because when the slurry pH is high, the surface charge density of HfC particles increases, and the thickness of the double electric layer on the surface of the particles increases, thereby increasing the repulsive barrier between the particles, thereby achieving the effect of stabilizing the slurry.

[0096] Example 2

[0097] Compared with Example 1, the difference is that

[0098] Step S3 is: 10.98g of HfC particles with a particle size of 1 μm, 25.62g of HfC particles with a particle size of 500nm, 7g of deionized water, and 0.654g of sodium hexametaphosphate are mixed uniformly to form HfC slurry; the solid content of the HfC slurry is 30 vol%; and the viscosity is 1.000 Pa·s.

[0099] The amounts of other raw materials and preparation conditions are the same as in Example 1.

[0100] The SEM image of the 2.5D carbon / HfC-SiC composite material prepared in this example is as follows: Figure 4As shown in the figure, it can be seen that the HfB introduced by SI 2 The particles and SiC are generally evenly dispersed, and the two are together filled between the fiber bundles to densify the material.

[0101] Example 3

[0102] Compared with Example 1, the difference is that

[0103] Step S3 is: 14.64g of HfC particles with a particle size of 1 μm, 34.16g of HfC particles with a particle size of 500nm, 6g of deionized water, and 0.822g of sodium hexametaphosphate are mixed uniformly to form HfC slurry; the solid content of the HfC slurry is 40 vol%; and the viscosity is 1.003 Pa·s.

[0104] The amounts of other raw materials and preparation conditions are the same as in Example 1.

[0105] The SEM image of the 2.5D carbon / HfC-SiC composite material prepared in this example is as follows: Figure 5 As shown in the figure, it can be seen that HfB is attached to the fiber surface. 2 Particles, while the SiC produced by the PIP process wraps the fiber, and some HfB 2 The particles are also wrapped and attached to SiC, and the two together fill the pores of the composite material.

[0106] Comparative Example 1

[0107] The preparation steps of a 2.5D carbon / silicon carbide composite material are as follows:

[0108] S1. Needle-punch PAN-based carbon fiber to a density of 0.4 g / cm 3 2.5D carbon fiber preform;

[0109] S2, placing the preform in a tubular furnace, introducing Ar gas at a flow rate of 100 mL / min, and heating the preform to 1150°C at a heating rate of 10°C / min and keeping the temperature for 30 min, then introducing methane gas at a flow rate of 300 mL / min for 30 min, and cooling the preform naturally to room temperature to obtain a 2.5D carbon matrix;

[0110] S3, 9.6g of silicon carbide particles, 7g of deionized water, and 0.166g of sodium hexametaphosphate were mixed evenly as SiC impregnation slurry. Dilute hydrochloric acid and ammonia water were used to adjust the slurry pH to 11;

[0111] S4, put the above 2.5D carbon base into a beaker, place the beaker in a vacuum tower, use a vacuum pump to evacuate for 30 minutes, then add 200 mL of the above SiC slurry into the beaker, continue to evacuate for 30 minutes, then slowly release the pressure to normal pressure, and place the green body in a 100°C oven to dry for 4 hours;

[0112] S5, putting the above green body into a beaker, placing the beaker in a reactor, introducing Ar gas until the pressure in the reactor reaches 5 MPa, maintaining for 5 hours, then slowly releasing the pressure to normal pressure, placing the green body in an oven at 100° C. and drying for 4 hours to obtain a carbon / silicon carbide composite green body;

[0113] S6, mixing 200 g of polycarbosilane and 200 g of xylene to obtain a precursor solution;

[0114] S7. Immerse the 2.5DC / SiC composite material body in the precursor solution, evacuate for 30 minutes, then put it into an oven and dry it at 150°C for 1 hour to complete the curing and cross-linking. Then, pyrolyze it at 1300°C in a tubular furnace for 30 minutes with a heating rate of 10°C / min. This is one cycle until the weight gain rate is less than 1%.

[0115] The SEM image of the 2.5D carbon / silicon carbide composite material prepared in Comparative Example 1 is as follows: Figure 6 As shown in the figure, it can be seen that the introduced SiC particles are filled in the gaps in the carbon fibers.

[0116] Effect verification

[0117] The density and ablation performance (refer to GJB 323A-96 standard) of the composite materials prepared in Examples 1 to 3 and Comparative Example 1 were tested, and the results are shown in Table 1.

[0118] Table 1

[0119]

[0120] It can be seen from the data in Table 1 that the density and ablation performance of the 2.5D carbon / hafnium carbide-silicon carbide composite materials prepared in Examples 1 to 3 of the present invention are better than those in Comparative Example 1. By adding different amounts of ultra-high temperature ceramics to the carbon matrix, the performance of the 2.5D carbon / hafnium carbide-silicon carbide composite materials can be enhanced, providing an option for adapting to more stringent aircraft service environments.

[0121] Compared with the existing carbon / hafnium carbide-silicon carbide composite material preparation process, the technical solution of the present invention not only shortens the composite material preparation cycle, but also provides a preparation method of a 2.5D carbon / hafnium carbide-silicon carbide composite material with better performance, providing in-depth theoretical support for future material design and application, and providing important reference and theoretical basis for further design and optimization of carbon / hafnium carbide-silicon carbide composite materials, thereby improving the diversity of composite material choices in high temperature environments.

[0122] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material, characterized in that: The steps include: A 2.5D carbon fiber preform is used as a matrix, pyrolytic carbon is deposited on the matrix by chemical vapor deposition, an ultra-high temperature ceramic phase is introduced by slurry infiltration, and then a precursor impregnation pyrolysis method is used for densification to prepare a 2.5D carbon / hafnium carbide-silicon carbide composite material; The slurry infiltration method uses HfC slurry, and its raw materials include: HfC particles with particle sizes of 1 μm and 500 nm, a dispersant and water.

2. The method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 1, characterized in that: The mass ratio of HfC particles with a particle size of 1 μm and 500 nm is 3:

7.

3. The method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 1, characterized in that: The mass ratio of the HfC particles, the dispersant and the deionized water is 20-50:0.4-0.9:6-8.

4. The method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 1, characterized in that: The dispersant is sodium hexametaphosphate; and the pH value of the HfC slurry is 3-11.

5. The method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 1, characterized in that: The preparation method of the 2.5D carbon / hafnium carbide-silicon carbide composite material specifically comprises the following steps: Using PAN-based carbon fiber as the matrix, needle-punched and woven into a 2.5D carbon fiber preform; Using chemical vapor deposition, a layer of pyrolytic carbon is deposited on the surface of the 2.5D carbon fiber preform using methane gas to obtain a 2.5D carbon matrix; The 2.5D carbon matrix is ​​sequentially vacuum impregnated and pressure impregnated into the HfC slurry by a slurry infiltration method, and a 2.5DC / HfC-SiC composite material blank is obtained after drying; The precursor impregnation pyrolysis method is adopted to cyclically treat the 2.5D CHfC-SiC composite material blank in a precursor solution by impregnation, drying and pyrolysis as a cycle until the weight gain rate is less than 1%, thereby obtaining the 2.5D carbon / hafnium carbide-silicon carbide composite material.

6. The method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 5, characterized in that: The conditions during chemical vapor deposition are: Under an inert atmosphere, heat to 1150°C at a heating rate of 10°C / min, then introduce methane gas at a gas flow rate of 300mL / min for 15 to 30min, and keep at 1150°C for 15 to 30min, and then cool naturally.

7. The method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 5, characterized in that: The vacuum impregnation process is: First, the 2.5D carbon substrate is vacuumed for 15 to 30 minutes; Then, the HfC slurry is immersed in the 2.5D carbon substrate, and the vacuum is maintained for 15 to 30 minutes and then naturally restored to normal pressure; and / or, The pressure impregnation process is as follows: the vacuum impregnated 2.5D carbon matrix is ​​completely immersed in the HfC slurry, pressurized to 4-5 MPa, maintained for 4-5 hours, and then released to normal pressure.

8. The method for preparing a 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 5, characterized in that: The precursor solution is a mixed solution of polycarbosilane and xylene in a mass ratio of 1:1; and / or, The drying temperature in the drying process is 150-160° C. and the drying time is 1-2 hours; and / or, The conditions in the pyrolysis process are: heating to 700-1300° C. at a heating rate of 10° C. / min, and then pyrolyzing at this temperature for 30-60 minutes.

9. A 2.5D carbon / hafnium carbide-silicon carbide composite material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the 2.5D carbon / hafnium carbide-silicon carbide composite material according to claim 9 in the preparation of a hypersonic aircraft.

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