Carbon / carbon composite materials modified with ytterbium silicide and organoceramics and their preparation methods

Abstract

This invention discloses a carbon / carbon composite material based on ytterbium silicide and organoceramic modification, and its preparation method, relating to the field of ceramic-modified composite materials technology. The method includes the following steps: ytterbium powder and nano-silica are mixed uniformly and sintered under an inert atmosphere and pressure conditions. After sintering, the mixture is cooled to room temperature and ball-milled to obtain ytterbium silicide powder. An organoceramic precursor and ytterbium silicide powder are dissolved or dispersed in a solvent to obtain an impregnation solution. The carbon / carbon composite matrix is ​​immersed in the impregnation solution and vacuum impregnated several times to obtain a sintering precursor. The sintering precursor is heated to 1500-1800℃ and sintered under an inert atmosphere and pressure conditions. After sintering, the mixture is cooled to room temperature. The impregnation and sintering steps are repeated 1-2 times to obtain the final product. The composite material of this invention exhibits better temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of ceramic-modified composite materials technology, specifically to a carbon / carbon composite material based on ytterbium silicide and organoceramics modification and its preparation method. Background Technology

[0002] With the rapid development of aerospace technology, the next generation of hypersonic vehicles is moving towards higher speeds and longer flight times. This places more stringent demands on the service performance of hot-end components in extreme environments, making the application of high-temperature thermal structural materials in the aerospace field increasingly crucial. Carbon / carbon (C / C) composites, as a strategically significant advanced high-temperature thermal structural material, have made unique contributions to reducing the structural weight of aircraft and improving their overall carrying capacity due to their low density, high specific modulus, extremely low coefficient of thermal expansion (CTE), and unique properties such as "increasing rather than decreasing" mechanical strength in high-temperature environments above 2000℃. They have become an important cornerstone for the development of national defense and the national economy. However, C / C composites have significant shortcomings in oxidation resistance. They begin to oxidize in oxygen-rich environments above 370℃, leading to damage to the carbon fiber skeleton and matrix. Especially during service, the material must withstand the dual challenges of extreme high temperatures generated by aerodynamic heating and strong shear erosion from high-speed airflow. This coupling effect of thermochemical oxidation and mechanical erosion causes rapid degradation of the material surface, seriously affecting the service reliability and safety of aircraft. Therefore, overcoming the bottleneck problem of insufficient high-temperature oxidation and ablation resistance in C / C composites has become a core focus urgently needing to be addressed in this field. To this end, introducing ultra-high temperature ceramics (UHTCs) into the carbon matrix for modification has become the mainstream technical approach. Among various preparation processes, the precursor impregnation pyrolysis (PIP) process, with its advantages of mild processing temperature, minimal fiber damage, low equipment requirements, and ease of forming large and complex components, especially its extremely high flexibility in multiphase ceramic composition design, has become the preferred process for preparing ablation-resistant C / C composites.

[0003] Although the PIP process has made some progress in introducing hafnium carbide-tantalum carbide solid solution to modify C / C composites, attempting to utilize the high melting point skeleton effect of HfC and the liquid phase filling potential of TaC oxidation products to synergistically resist ablation, the existing Hf-Ta-C system still exhibits significant limitations under extreme ablation environments. Reference 1, "JC Li, T. Li, CJHuang, YL Zhang. The synergistic effect of multi-phase oxides on theablation resistance of TaC-modified HfC-ZrC coatings for C / C composites [J]. Corrosion Science, 2024, 228: 111795," introduces liquid Ta2O5 into the HfC-ZrC coating by adjusting the TaC content, attempting to utilize it to heal cracks and form a dense Ta-doped oxide layer. Nevertheless, studies have shown that the oxidation product of TaC, Ta2O5, has a low melting point (approximately 1800℃) and excessively low viscosity at ultra-high temperatures, making it highly susceptible to mechanical erosion by high-speed airflows. This results in ablation pits on the coating surface, compromising its integrity and failing to provide long-term protection. Reference 2, "SP Liu, Z.Ma, YB Liu, et al. Ablation performance of Ta0.8Hf0.2C-SiC coating fabricated via pack cementation for carbon / carbon composites [J]. Journal of the European Ceramic Society, 2025, 45: 117064," describes the preparation of Ta2O5 using an embedding method. 0.8 Hf 0.2 C-SiC coating, utilizing HfO2 / Hf6Ta2O 17The pinning effect of particles on liquid Ta2O5 improves ablation resistance. However, this literature also points out that after the liquid phase is lost, the remaining HfO2 skeleton, due to its extremely high melting point, lacks sufficient liquid sealing phase to fill the grain boundaries, resulting in a loose and porous structure of the oxide layer, which loses its ability to effectively block oxygen diffusion; in addition, the crystal transformation of HfO2 during cooling can also cause volume expansion, leading to coating cracking. Literature 3, "ZY Tan, ZY Liu, YJ Hu, et al. Multiscale structural understanding of plasma spraying anti-ablation coating: an example of Ta-Hf-WC ultrahigh temperature ceramics [J]. Corrosion Science, 2024, 234: 112130," studies the ablation behavior of Ta-Hf-WC ultrahigh temperature ceramic coatings. Studies have revealed that the thermodynamically rich TaC phase exhibits a higher oxidation tendency, leading to early depletion of Ta2O5. Furthermore, since the melting point of Ta2O5 is much lower than the ablation temperature, some oxides evaporate directly during the reaction, making it difficult to maintain the stoichiometric stability and structural continuity of the oxide layer under extreme heat flux conditions. Therefore, the existing Hf-Ta-C system struggles to balance liquid-phase retention at ultra-high temperatures with framework compactness, necessitating the search for a new modifying component and preparation method.

[0004] To address the challenges of high-temperature liquid phase loss and oxide layer phase transformation cracking in the Hf-Ta-C system, a novel modifying component is urgently needed to enhance the structural stability and self-healing ability of the oxide layer. The introduction of ytterbium disilicide (YbSi2) offers a new approach: the rare-earth element Yb effectively suppresses the crystal transformation of HfO2, alleviating internal stress caused by volume effects; simultaneously, the ytterbium silicate glass phase formed in situ by Yb and Si at high temperatures has a higher melting point and more suitable high-temperature viscosity compared to Ta2O5, effectively resisting gas flow shear and firmly adhering to and sealing defects in the HfO2 framework. Therefore, developing a C / C composite material based on YbSi2 modification is of great significance for overcoming the performance bottlenecks of the existing Hf-Ta-C system. Summary of the Invention

[0005] To address at least one of the aforementioned problems, this invention provides a carbon / carbon composite material based on ytterbium silicide and organoceramic modification, and a method for its preparation.

[0006] The technical solution of this invention to solve the above problems is as follows: A method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification, comprising the following steps: S1. Take ytterbium powder and nano-silica in a molar ratio of 1:2~2.1 and mix them evenly. Under inert atmosphere and pressure conditions, heat to 1400~1700℃ and sinter. After sintering, cool to room temperature and ball mill to obtain silicided ytterbium powder. S2. Take the organic ceramic precursor and ytterbium silicide powder and add them to a solvent to dissolve or disperse them to obtain an impregnation solution; wherein the mass ratio of the organic ceramic precursor to the ytterbium silicide powder is 3:1~3; S3. The carbon / carbon composite matrix is ​​immersed in the impregnation liquid and vacuum impregnated several times to obtain the sintering precursor. S4. Take the sintering precursor, heat it to 1500~1800℃ and sinter it under inert atmosphere and pressure conditions, and cool it to room temperature after sintering. S5. Repeat the operations of S3 to S4 1 to 2 times to obtain the result.

[0007] In one embodiment of the present invention, the inert atmosphere refers to either a helium atmosphere or an argon atmosphere, and the pressure condition refers to a sintering pressure of 50~200kPa.

[0008] In one embodiment of the present invention, the sintering time in S1 is 1-2 hours, and the sintering time in S4 is 2-4 hours. In actual production, the heating rate can be set according to existing heating rates. For example, the heating rate can be faster under initial conditions, such as 10°C / min. When the temperature rises above 800°C, the heating rate gradually decreases. When the final temperature rises to 1400°C, the heating rate should not be too fast, usually controlled at 2-3°C / min. This method of setting the heating rate is conventional in the art and therefore will not be described in detail.

[0009] In one embodiment of the present invention, in step S1, the ball milling includes coarse grinding and fine grinding: coarse grinding uses 5mm grinding balls and 2mm grinding balls with a mass ratio of 1:0.5~2, with anhydrous ethanol as a grinding aid, and the ball milling time is 12~24h; fine grinding uses 2mm grinding balls and 1mm grinding balls with a mass ratio of 1:1.5~2.5, with anhydrous ethanol as a grinding aid, and the ball milling time is 12~24h.

[0010] In one embodiment of the present invention, in step S2, the organoceramic precursor is one of a TaC precursor and an HfC precursor, the solvent used is methanol or ethanol, and the total concentration of the organoceramic precursor and ytterbium silicide powder is 10-30 wt%. Meanwhile, for carbon / carbon composite materials, considering the cleanliness of their surface, they can be cleaned and dried before use: during cleaning, they are cleaned several times using an ultrasonic cleaner and deionized water, and after cleaning, they are dried at 100-110°C.

[0011] In one embodiment of the present invention, in step S3, the single immersion time is 15-30 minutes, and the number of immersions is 2-4.

[0012] Furthermore, in S3, after a single impregnation, the carbon / carbon composite material is dried at 80~100℃. After drying, the carbon / carbon composite material is placed in anhydrous ethanol and sonicated for 1~5 minutes. After sonication, the carbon / carbon composite material is removed and dried to remove the anhydrous ethanol.

[0013] Another object of the present invention is to disclose a carbon / carbon composite material based on ytterbium silicide and organoceramic modification, which is prepared by any of the methods described above.

[0014] The beneficial effects of this invention are as follows: The composite material prepared by the method of this invention overcomes the problems of uneven composition and numerous impurity phases in the prior art: Compared with the uneven coating thickness easily caused by the embedding method and the defects of easy oxidation of raw materials in plasma spraying, the PIP process of this invention can precisely control Ta through the precursor solution ratio. x Hf 1-x The doping ratio of C to YbSi2 is controlled, and the entire pyrolysis and heat treatment process is carried out in an inert atmosphere, resulting in high purity and uniform component distribution of the ceramic product.

[0015] Compared to traditional coatings, the YbSi2 doped phase introduced in this invention has a higher operating temperature, and it can also withstand Ta... x Hf 1-x The C-frame self-repairs microcracks at high temperatures, improving the long-term reliability of the material. Attached Figure Description

[0016] Figure 1 The X-ray diffraction pattern of the composite material prepared in Example 1; Figure 2 The cross-sectional SEM image of the composite material obtained in Example 1; Figure 3 The image shows the elemental surface scan of the energy dispersive spectroscopy (EDS) of the composite material prepared in Example 1. Detailed Implementation

[0017] The specific embodiments of the present invention will be clearly and completely described below with reference to examples. Obviously, the described examples are only some embodiments of the present invention, and not all embodiments.

[0018] Unless otherwise specified, all pharmaceutical agents used in the following examples are conventional commercial products.

[0019] Unless otherwise specified, all operations used in the following embodiments are conventional operations in the art.

[0020] In the following embodiments, the carbon / carbon composite material used was prepared by alternating layers of carbon fiber nonwoven fabric and carbon fiber mesh through needle punching to obtain a preform, which was then densified by chemical vapor deposition (propylene as the carbon source, temperature 900°C). Before use, it was cleaned three times in an ultrasonic cleaner with deionized water and then dried at 105°C for 24 hours.

[0021] Example 1: A method for preparing a carbon / carbon composite material based on ytterbium silicide and organoceramic modification, comprising the following steps: S1. Ytterbium powder and nano-silica were mixed in a molar ratio of 1:2.1 and ball-milled until homogeneous. The mixture was then placed in a tube furnace and sintered at 1600℃ for 1 hour under an argon atmosphere and 1 atmosphere. After sintering, the product was allowed to cool naturally to room temperature to obtain a block. The block was then subjected to coarse grinding and fine grinding to obtain ytterbium silicide powder. The coarse grinding conditions were: using 5mm and 2mm grinding balls in a mass ratio of 1:1.5, with anhydrous ethanol as a grinding aid, for 15 hours. The fine grinding conditions were: using 2mm and 1mm grinding balls in a mass ratio of 1:2, with anhydrous ethanol as a grinding aid, for 15 hours.

[0022] S2. Take TaC precursor and ytterbium silicide powder in a mass ratio of 3:2, add them to ethanol, and sonicate them to dissolve or disperse them to obtain an impregnation solution. The total concentration of TaC precursor and ytterbium silicide powder in the impregnation solution is 22wt%.

[0023] S3. Place the carbon / carbon composite matrix in the impregnation solution and use the vacuum impregnation method to impregnate 4 times, with each impregnation time being 20 minutes, to obtain the sintering precursor. After each impregnation, dry at 85°C for 5 hours. After drying, place the impregnated carbon / carbon composite matrix in anhydrous ethanol and sonicate for 3 minutes. The sonication is mainly to remove the loosely bonded modified material on the carbon / carbon composite matrix. After sonication, continue drying at 85°C for 5 hours. Then repeat the vacuum impregnation operation until the number of impregnations reaches 4.

[0024] S4. Take the sintering precursor, heat it to 1600℃ and hold it for sintering for 3 hours under an argon atmosphere and 1 atmosphere. After sintering, let it cool naturally to room temperature. S5, repeat the impregnation operation of S3 and the sintering operation of S4 once, and finally obtain a carbon / carbon composite material based on ytterbium silicide and organoceramic modification.

[0025] The microscopic standards of the carbon / carbon composite material based on ytterbium silicide and organoceramic modification obtained in this embodiment were specifically as follows: Figures 1-3 As shown, where, Figure 1 This is an X-ray diffraction pattern. Figure 2 For SEM photos, Figure 3 This is an elemental surface scan map using energy-dispersive spectroscopy (EDS). From Figures 1-3 It can be seen that this embodiment successfully loaded ytterbium silicide and ceramics onto the surface of carbon / carbon composite material.

[0026] Example 2: A method for preparing a carbon / carbon composite material based on ytterbium silicide and organoceramic modification, comprising the following steps: S1. Ytterbium powder and nano-silica were mixed in a molar ratio of 1:2.1 and ball-milled until homogeneous. The mixture was then placed in a tube furnace and sintered at 1500℃ under an argon atmosphere and 1 atmosphere for 1 hour. After sintering, the product was allowed to cool naturally to room temperature to obtain a block. The block was then subjected to coarse grinding and fine grinding to obtain ytterbium silicide powder. The coarse grinding conditions were: using 5mm and 2mm grinding balls in a mass ratio of 1:1, with anhydrous ethanol as a grinding aid, for 20 hours; the fine grinding conditions were: using 2mm and 1mm grinding balls in a mass ratio of 1:2, with anhydrous ethanol as a grinding aid, for 15 hours.

[0027] S2. Take TaC precursor and ytterbium silicide powder in a mass ratio of 3:1.5, add them to ethanol, and sonicate them to dissolve or disperse them to obtain an impregnation solution. The total concentration of TaC precursor and ytterbium silicide powder in the impregnation solution is 28 wt%.

[0028] S3. Place the carbon / carbon composite matrix in the impregnation solution and impregnate it twice using the vacuum impregnation method. The impregnation time for each time is 28 min, to obtain the sintering precursor. After each impregnation, dry it at 85℃ for 5 h. After drying, place the impregnated carbon / carbon composite matrix in anhydrous ethanol and sonicate it for 3 min. After sonication, continue to dry it at 85℃ for 5 h. Then repeat the vacuum impregnation operation until the number of impregnations reaches 2.

[0029] S4. Take the sintering precursor, heat it to 1700℃ and hold it for sintering for 2.5h under an argon atmosphere and 1 atmosphere. After sintering, let it cool naturally to room temperature. S5, repeat the impregnation operation of S3 and the sintering operation of S4 once, and finally obtain a carbon / carbon composite material based on ytterbium silicide and organoceramic modification.

[0030] Example 3: A method for preparing a carbon / carbon composite material based on ytterbium silicide and organoceramic modification, comprising the following steps: S1. Ytterbium powder and nano-silica were mixed in a molar ratio of 1:2.1 and ball-milled until homogeneous. The mixture was then placed in a tube furnace and sintered at 1400℃ for 2 hours under an argon atmosphere and 1 atmosphere. After sintering, the product was allowed to cool naturally to room temperature to obtain a block. The block was then subjected to coarse grinding and fine grinding to obtain ytterbium silicide powder. The coarse grinding conditions were: using 5mm and 2mm grinding balls in a mass ratio of 1:1, with anhydrous ethanol as a grinding aid, for 20 hours; the fine grinding conditions were: using 2mm and 1mm grinding balls in a mass ratio of 1:2, with anhydrous ethanol as a grinding aid, for 15 hours.

[0031] S2. Take TaC precursor and ytterbium silicide powder in a mass ratio of 3:2.5, add them to ethanol, and sonicate them to dissolve or disperse them to obtain an impregnation solution. The total concentration of TaC precursor and ytterbium silicide powder in the impregnation solution is 14wt%.

[0032] S3. Place the carbon / carbon composite matrix in the impregnation solution and impregnate it three times using the vacuum impregnation method. Each impregnation time is 15 minutes to obtain the sintering precursor. After each impregnation, dry it at 85°C for 5 hours. After drying, place the impregnated carbon / carbon composite matrix in anhydrous ethanol and sonicate it for 3 minutes. After sonication, continue drying at 85°C for 5 hours. Then repeat the vacuum impregnation operation until the number of impregnations reaches 3.

[0033] S4. Take the sintering precursor, heat it to 1600℃ and hold it for sintering for 3 hours under an argon atmosphere and 1 atmosphere. After sintering, let it cool naturally to room temperature. S5, repeat the impregnation operation of S3 and the sintering operation of S4 twice to finally obtain a carbon / carbon composite material based on ytterbium silicide and organoceramic modification.

[0034] Example 4: A method for preparing a carbon / carbon composite material based on ytterbium silicide and organoceramic modification, comprising the following steps: S1 is the same as in Example 1.

[0035] S2. Take HfC precursor and ytterbium silicide powder in a mass ratio of 3:1.8, add them to ethanol, and sonicate them to dissolve or disperse them to obtain an impregnation solution. The total concentration of TaC precursor and ytterbium silicide powder in the impregnation solution is 24wt%.

[0036] S3. Place the carbon / carbon composite matrix in the impregnation solution and use the vacuum impregnation method to impregnate 3 times, with each impregnation time being 18 minutes, to obtain the sintering precursor. After each impregnation, dry at 85°C for 5 hours. After drying, place the impregnated carbon / carbon composite matrix in anhydrous ethanol and sonicate for 3 minutes. After sonication, continue drying at 85°C for 5 hours. Then repeat the vacuum impregnation operation until the number of impregnations reaches 3.

[0037] S4. Take the sintering precursor, heat it to 1650℃ and hold it for sintering for 2 hours under an argon atmosphere and 1 atmosphere. After sintering, let it cool naturally to room temperature. S5, repeat the impregnation operation of S3 and the sintering operation of S4 once, and finally obtain a carbon / carbon composite material based on ytterbium silicide and organoceramic modification.

[0038] Comparative Example 1 differs from Example 1 in that after S4 is cooled to room temperature, S3 and S4 are not repeated.

[0039] Comparative Example 2 differs from Example 1 in that the ytterbium silicide powder is replaced with ytterbium silicate powder that has undergone the same ball milling process. The preparation of ytterbium silicate powder is a prior art technique, see the paper "Preparation and Performance Study of Ytterbium Silicate Coating for Carbon / Carbon Composite Materials".

[0040] To further illustrate the performance of the composite materials obtained in the embodiments of the present invention and the comparative examples, tests were conducted on them below.

[0041] Mechanical property testing was conducted on an electronic universal testing machine with a loading rate of 1 mm / min and the load direction perpendicular to the plane of the carbon-carbon composite material.

[0042] The ablation rate test was conducted on a high-frequency plasma torch ablation tester at a temperature of 2000℃.

[0043] The final results are shown in Table 1.

[0044] Table 1 Test Results As shown in Table 1, the composite material prepared in the embodiments of the present invention has good mechanical properties and good temperature resistance.

[0045] The present invention has been disclosed above with preferred embodiments. However, those skilled in the art should understand that these embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Further improvements can be made without departing from the principles of the invention, and these improvements should also be considered as protections of the present invention.

Claims

1. A method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification, characterized in that, Includes the following steps: S1. Take ytterbium powder and nano-silica in a molar ratio of 1:2~2.1 and mix them evenly. Under inert atmosphere and pressure conditions, heat to 1400~1700℃ and sinter. After sintering, cool to room temperature and ball mill to obtain silicided ytterbium powder. S2. Take the organic ceramic precursor and ytterbium silicide powder and add them to a solvent to dissolve or disperse them to obtain an impregnation solution; wherein the mass ratio of the organic ceramic precursor to the ytterbium silicide powder is 3:1~3; S3. The carbon / carbon composite matrix is ​​immersed in the impregnation liquid and vacuum impregnated several times to obtain the sintering precursor. S4. Take the sintering precursor, heat it to 1500~1800℃ and sinter it under inert atmosphere and pressure conditions, and cool it to room temperature after sintering. S5. Repeat the operations of S3 to S4 1 to 2 times to obtain the result.

2. The method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification according to claim 1, characterized in that, The inert atmosphere refers to either a helium atmosphere or an argon atmosphere, and the pressure condition refers to a sintering pressure of 50~200kPa.

3. The method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification according to claim 1, characterized in that, In S1, the sintering time is 1~2h, and in S4, the sintering time is 2~4h.

4. The method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification according to claim 1, characterized in that, In S1, the ball milling includes coarse grinding and fine grinding: coarse grinding uses 5mm grinding balls and 2mm grinding balls with a mass ratio of 1:0.5~2, with anhydrous ethanol as a grinding aid, and the ball milling time is 12~24h; fine grinding uses 2mm grinding balls and 1mm grinding balls with a mass ratio of 1:1.5~2.5, with anhydrous ethanol as a grinding aid, and the ball milling time is 12~24h.

5. The method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification according to claim 1, characterized in that, In S2, the organic ceramic precursor is either a TaC precursor or an HfC precursor, the solvent used is methanol or ethanol, and the total concentration of the organic ceramic precursor and ytterbium silicide powder is 10~30wt%.

6. The method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification according to claim 1, characterized in that, In S3, the single immersion time is 15~30 minutes, and the number of immersions is 2~4 times.

7. The method for preparing carbon / carbon composite materials based on ytterbium silicide and organoceramic modification according to claim 6, characterized in that, In S3, after a single impregnation, the carbon / carbon composite material is dried at 80~100℃. After drying, the carbon / carbon composite material is placed in anhydrous ethanol and sonicated for 1~5 minutes. After sonication, the carbon / carbon composite material is removed and dried to remove the anhydrous ethanol.

8. A carbon / carbon composite material based on ytterbium silicide and organoceramic modification, prepared by the method described in any one of claims 1 to 7.

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