Long-life ablation-resistant special-shaped C / C composite material and preparation method thereof

Abstract

The application belongs to the technical field of composite materials, and particularly relates to a long-life ablation-resistant special-shaped C / C composite material and a preparation method thereof. The preparation method of the long-life ablation-resistant special-shaped C / C composite material comprises the following steps: processing low-density C / C composite material into a special-shaped appearance containing trapezoidal side surfaces and sharp inclined surfaces to obtain a special-shaped C / C composite material; placing the special-shaped C / C composite material in alloy powder for a melt infiltration reaction to introduce an ultra-high-temperature ceramic modified phase, thereby obtaining a matrix-modified special-shaped C / C composite material; preparing an ultra-high-temperature ceramic coating on the trapezoidal side surfaces and the sharp inclined surfaces of the matrix-modified special-shaped C / C composite material, thereby obtaining a coating-matrix-modified special-shaped C / C composite material; and depositing a SiC sealing coating on the surface of the coating-matrix-modified special-shaped C / C composite material, thereby obtaining a long-life ablation-resistant special-shaped C / C composite material.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a long-life, ablation-resistant irregular C / C composite material and its preparation method. Background Technology

[0002] With the rapid development of commercial spaceflight in recent years, heavy-lift launch vehicles are increasingly evolving towards lower cost, higher reliability, reusability, and higher precision. Among these, achieving precise recovery and reuse of the vehicle is crucial for reducing its launch costs. During the recovery process, the combined control of irregularly shaped thermal structural components is key to ensuring continuous, uninterrupted, and wide-range aerodynamic attitude adjustments. These components are often complex cylindrical structures with leading-edge bevels and trapezoidal or triangular sides. However, during reentry, the vehicle faces ultra-high-temperature ablation due to intense aerodynamic heating. The structural integrity and dimensional accuracy of these irregularly shaped components are easily compromised by stagnation ablation, leading to reduced recovery accuracy and even catastrophic recovery failures. Therefore, improving the ablation resistance of these irregularly shaped spacecraft components is essential for the reliable service of the next generation of reusable heavy-lift launch vehicles.

[0003] Existing flight attitude control components typically employ a configuration combining an outer surface layer and a supporting frame. This involves a variable-thickness, high-temperature resistant quartz-based composite material surface layer with a load-bearing alloy frame to achieve integrated performance requirements for heat protection, load bearing, and ablation resistance. However, since the allowable temperatures of aluminum and titanium alloys are often below 2000 °C, the significant decrease in alloy mechanical strength under ultra-high temperature conditions severely restricts the overall structural reliability. To mitigate the strength degradation rate of the alloy frame during high-temperature service, a heat insulation layer composed of low thermal conductivity oxide ceramic materials is often added between the composite material surface layer and the load-bearing alloy frame. However, the composite design of multiple material types results in excessively high density in the irregular structure, making it difficult to achieve a lightweight overall design and hindering the achievement and comprehensive optimization of high-temperature service performance indicators. Therefore, there is an urgent need to develop a new generation of composite materials for overall replacement, and to design new composite material systems that combine lightweight and high-temperature resistance.

[0004] Carbon / carbon (C / C) composites benefit from their low density (<2.0 g / cm³). 3C / C composites possess a series of advantages, including high temperature resistance (>3000 ℃), high specific strength, and high-temperature mechanical strength that increases with temperature, making them one of the best materials for next-generation high-temperature thermal structural components. Using C / C composites to prepare high-temperature resistant, lightweight irregular structures has become a feasible technical route. However, C / C composites experience oxidation weight loss and strength degradation when used in oxidative ablation environments above 400 ℃, severely limiting their long-term reliable service in high-temperature oxygen-containing environments. The key technologies for extending the service life of C / C composites in ultra-high-temperature oxygen-containing environments are currently the use of thermally protective coatings, C / C matrix anti-oxidation and ablation-resistant modification, and their combination. In Chinese invention patent CN115611647B, the inventors, based on the idea of ​​synergistic anti-oxidation and ablation resistance through carbon-based composite coating and matrix modification, combined a high thermal conductivity carbon material with "rapid heat dissipation" capability with a novel multi-element ceramic composite with "high oxygen barrier and resistance to gas erosion," achieving an ablation resistance time of more than 1500 s in an oxyacetylene ablation environment.

[0005] However, existing research reports on long-life, oxidation-resistant, and ablation-resistant matrix modification and coatings mostly focus on C / C composites with regular geometric shapes. There are few reports on the overall preparation of integrally modified irregularly shaped C / C composites with integrated coating and matrix modifications. Improving the property matching and stable bonding between the coating and the matrix of complex irregularly shaped C / C surfaces remains a challenge. Meanwhile, the service behavior and protection mechanism of irregularly shaped C / C composites under ultra-high temperature ablation conditions are still unclear. Therefore, there is an urgent need to develop novel ultra-high temperature coated matrix-modified irregularly shaped C / C composites that combine low density, high temperature resistance, and long-term oxidation and ablation resistance to meet the performance requirements of long-life, stable service for thermal structural components of next-generation commercial aerospace vehicles. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing long-life, ablation-resistant irregular C / C composite materials, which solves the problems of high density, insufficient high-temperature resistance, and limited ablation resistance of aerospace irregular parts prepared in the prior art.

[0007] The present invention also provides a long-life, ablation-resistant irregular C / C composite material to solve the problems of high density, insufficient high-temperature resistance, and limited ablation resistance of irregularly shaped aircraft components in the prior art.

[0008] To address the aforementioned problems, this invention proposes a method for preparing a long-life, ablation-resistant irregular C / C composite material. The technical solution adopted is as follows: A method for preparing a long-life, ablation-resistant irregular C / C composite material includes the following steps: (1) Process the low-density C / C composite material into an irregular shape containing trapezoidal sides and sharp bevels to obtain an irregular C / C composite material; (2) The irregular C / C composite material is placed in alloy powder for melt infiltration reaction to introduce ultra-high temperature ceramic modified phase, so as to obtain matrix modified irregular C / C composite material; (3) Prepare ultra-high temperature ceramic coatings on the trapezoidal side surface and sharp bevel of the matrix-modified irregular C / C composite material to obtain the coating-matrix modified irregular C / C composite material; (4) A SiC sealing coating is deposited on the surface of the coating-matrix modified irregular C / C composite material to obtain a long-life ablation resistant irregular C / C composite material.

[0009] In order to prepare a ZrC-ZrSi2-B4C coating, which makes it easier for the ultra-high temperature ceramic coating to cover the matrix-modified irregular C / C composite material and improve its density, preferably, in step (3), the ultra-high temperature ceramic coating is composed of three ultra-high temperature ceramics: ZrC, ZrSi2, and B4C; the mass percentages of ZrC, ZrSi2, and B4C in the ultra-high temperature ceramic coating are 50-70%, 20-30%, and 10-20%, respectively.

[0010] To further improve the oxidation and ablation resistance of the long-life, ablation-resistant irregular C / C composite material, preferably, the thickness of the ultra-high temperature ceramic coating is 100~200 μm, and the thickness of the SiC sealing coating is 100~200 μm.

[0011] In order to improve the preparation efficiency and density of ultra-high temperature ceramic coating, preferably, in step (3), the preparation of ultra-high temperature ceramic coating adopts supersonic atmospheric plasma spraying technology. The process parameters of supersonic atmospheric plasma spraying technology are as follows: the excitation gas of plasma is Ar and H2, the pressure and flow rate of Ar are 1.05~1.35 MPa and 65~75 L / min respectively, the pressure and flow rate of H2 are 1.10~1.20 MPa and 1~3 L / min respectively, and the excitation power of plasma is 45~50 kW.

[0012] To further densify the carbon fiber preform and obtain a low-density C / C composite material, preferably, the preparation method of the low-density C / C composite material includes the following steps: Pyrolytic carbon is deposited on a carbon fiber preform to obtain a matrix C / C composite material; the matrix C / C composite material is then graphitized to obtain a low-density C / C composite material.

[0013] Preferably, the graphitization treatment temperature is 2000~2400 ℃, the graphitization treatment atmosphere is Ar, and the graphitization treatment time is 0.5~2 hours.

[0014] Preferably, the density of the matrix C / C composite material is 1.30~1.40 g / cm³. 3 The density of the low-density C / C composite material is 1.25~1.35 g / cm³. 3 .

[0015] Preferably, the deposition of pyrolytic carbon is performed using the CVI process.

[0016] Preferably, in step (2), the alloy powder is MSi2, where M is Hf, Zr, Ti, or Ta, and the purity of the powder alloy powder is 99.9%, with a particle size of 10~50 μm. The alloy powder melts in a high-temperature environment to form a liquid melt. Under the action of capillary force, the melt penetrates into the pores inside the low-density C / C composite material. Subsequently, the melt inside the C / C composite material undergoes a chemical reaction with the carbon matrix to form an ultra-high temperature ceramic modified phase with high-temperature oxidation resistance, which fully fills the pores of the C / C composite material, thereby achieving densification and oxidation resistance modification of the irregular C / C composite material. Since HfSi2, ZrSi2, TiSi2, and TaSi2 have similar physicochemical properties, their reaction mechanisms during the reaction melting process are completely consistent. They can be introduced into the irregular C / C composite material in one step through reaction melting with the same process parameters, namely HfC-SiC, ZrC-SiC, TiC-SiC, and TaC-SiC ultra-high temperature ceramic phases, respectively.

[0017] Preferably, the process further includes the following after step (3): The coating-matrix modified irregular C / C composite material is cleaned and dried. The drying process is carried out at a temperature of 70~90 ℃ for 0.5~2 hours.

[0018] Preferably, in step (2), the temperature of the melting and infiltration reaction is 1600~2000 ℃, the gas pressure inside the vacuum heat treatment furnace is negative, and the gas pressure is maintained at 6~10 Pa.

[0019] The present invention also proposes a long-life, ablation-resistant, irregularly shaped C / C composite material prepared by the aforementioned preparation method, wherein the long-life, ablation-resistant, irregularly shaped C / C composite material is a columnar structure with trapezoidal sides and sharp bevels.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a method for preparing a long-life, ablation-resistant, irregularly shaped C / C composite material. The method involves sequentially introducing an ultra-high temperature ceramic modifier phase with high-temperature oxidation resistance into a C / C composite matrix with a complex irregular shape for densification and modification, resulting in a matrix-modified irregularly shaped C / C composite material. Subsequently, an ultra-high temperature ceramic coating is prepared on the leading edge and trapezoidal side surfaces of the matrix-modified irregularly shaped C / C composite material. Finally, a SiC sealing coating is prepared on the surface of the ultra-high temperature ceramic coating, achieving the preparation of a double-layer coating on the surface of the irregularly shaped C / C composite material. The resulting long-life, ablation-resistant, irregularly shaped C / C composite material not only ensures oxidation and ablation resistance but also possesses low density and ultra-high temperature tolerance. It exhibits excellent long-life ablation resistance and is suitable for long-term ultra-high temperature oxidation and ablation environments up to 2500 ℃. Compared with existing technical solutions for protecting refractory alloy irregularly shaped components with ceramic coatings, this method effectively solves the challenges of lightweight design and insufficient high-temperature reliability. Furthermore, this invention innovatively designs a double-layer coating structure consisting of a SiC sealing outer coating and an ultra-high temperature ceramic inner coating. The outer SiC sealing coating provides an oxygen-barrier self-healing effect, while the inner ultra-high temperature ceramic coating ensures the overall coating's mechanical load-bearing capacity and resistance to ablation thermal shock. Compared to traditional single-layer oxide coatings for irregularly shaped components, this invention exhibits superior high-temperature stability, high-temperature resistance, and oxidation and ablation resistance, playing a crucial role in ensuring the reliable service of irregularly shaped C / C components.

[0021] The present invention proposes a method for preparing a long-life, ablation-resistant irregularly shaped C / C composite material, which is simple in procedure, low in raw material cost, and has a short preparation cycle. The irregularly shaped C / C composite material prepared by the method of this application has an overall density of 2.79~2.91 g / cm³. 3 The test specimen can achieve a heat flux density of 10 MW / m 2 After 2100 s of cyclic ablation in an Ar-H2 plasma flame with an incoming flow temperature of 2500-3000 ℃, the structure remained intact, and the coating did not experience large-scale cracking or peeling. Its mass ablation rate and linear ablation rate were as low as 0.397 mg / s and -0.271 μm / s, respectively, demonstrating excellent performance that combines lightweight, high temperature resistance and ablation resistance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process flow for preparing the long-life, ablation-resistant irregular C / C composite material of the present invention; Figure 2 Macroscopic morphology photographs of the long-life, ablation-resistant irregular C / C composite materials prepared for various embodiments of the present invention, wherein: (a) Example 1; (b) Example 2; (c) Example 3; Figure 3 This is a schematic diagram of the long-term cyclic ablation test process of the long-life ablation-resistant irregular C / C composite material prepared in Example 1 of the present invention. Figure 4 Images of the long-life, ablation-resistant, irregularly shaped C / C composite material prepared in Example 1 of this invention during long-term cyclic ablation at various postures; wherein: (a) a photo of the ablation process in posture 1; (b) a photo of the ablation process in posture 2; (c) a photo of the ablation process in posture 3. Figure 5 The macroscopic morphology of the long-life, ablation-resistant irregular C / C composite material prepared in Example 1 of this invention before and after ablation is shown in the following figures: (a) before ablation; (b) ablation after 300 s; (c) ablation after 600 s; (d) ablation after 900 s; (e) ablation after 1200 s; (f) ablation after 1500 s; (g) ablation after 1800 s; (h) ablation after 2100 s. Figure 6 The images show cross-sectional SEM images of the long-life, ablation-resistant irregular C / C composite material prepared in Example 1 of this invention after 2100 s of ablation, including: (a) the leading edge of the irregular C / C composite material; and (b) [other images]. Figure 6 (a) Local magnification. Detailed Implementation

[0023] Existing technologies produce aerospace-grade irregular alloy components with high density, insufficient high-temperature resistance, and limited ablation resistance. Therefore, this invention proposes a method for preparing long-life, ablation-resistant irregular C / C composite materials, comprising the following steps: (1) Process the low-density C / C composite material into an irregular shape containing trapezoidal sides and sharp bevels to obtain an irregular C / C composite material; (2) The irregular C / C composite material is placed in alloy powder for melt infiltration reaction to introduce ultra-high temperature ceramic modified phase, so as to obtain matrix modified irregular C / C composite material; (3) Prepare ultra-high temperature ceramic coatings on the trapezoidal side surface and sharp bevel of the matrix-modified irregular C / C composite material to obtain the coating-matrix modified irregular C / C composite material; (4) A SiC sealing coating is deposited on the surface of the coating-matrix modified irregular C / C composite material to obtain a long-life ablation resistant irregular C / C composite material.

[0024] The technical concept of this invention is as follows: First, a low-density C / C composite material is processed into an irregular shape containing trapezoidal sides and sharp bevels to obtain an irregularly shaped C / C composite material. The irregular shape of the low-density C / C composite material is used to reduce the resistance of reactive infiltration (RMI) during matrix modification, ensuring the net dimensional shaping of the ultra-high temperature ceramic-modified irregularly shaped C / C composite material. Then, the irregularly shaped C / C composite material is placed in alloy powder for a melt infiltration reaction to introduce an ultra-high temperature ceramic modifier phase, resulting in a matrix-modified irregularly shaped C / C composite material. This ultra-high temperature ceramic modifier phase possesses high-temperature oxidation resistance, which fully fills the pores of the irregularly shaped C / C composite material and achieves densification and oxidation resistance modification, thereby improving the oxidation resistance and ablation resistance of the matrix-modified irregularly shaped C / C composite material. Next, an ultra-high temperature ceramic coating is prepared on the leading edge and trapezoidal side surface of the matrix-modified irregular C / C composite material, resulting in a coating-matrix-modified irregular C / C composite material, further improving the oxidation resistance and ablation resistance of the matrix-modified irregular C / C composite material. Finally, a SiC sealing coating is deposited on the surface of the coating-matrix-modified irregular C / C composite material to obtain a long-life ablation-resistant irregular C / C composite material. The SiC sealing coating eliminates defects such as voids or cracks on the surface of the sprayed coating, enabling the long-life ablation-resistant irregular C / C composite material to possess high oxidation and ablation resistance, as well as low density and ultra-high temperature tolerance. The long-life ablation-resistant irregular C / C composite material obtained in this application exhibits advantages such as low density, high temperature resistance, and excellent ablation resistance.

[0025] Specifically, the preparation method of long-life, ablation-resistant irregular C / C composite materials, such as... Figure 1 As shown, it includes the following steps: Step 1: The carbon fiber preform obtained by three-dimensional weaving is placed in the isothermal chemical vapor infiltration (CVI) furnace. CH4 gas is used as the carbon source in the CVI densification process. Under negative pressure conditions, pyrolytic carbon deposition and graphitization are carried out to achieve densification of the carbon fiber preform, obtaining a low-density C / C composite material. The graphitization treatment temperature is 2000~2400 ℃, the atmosphere is Ar, and the time is 0.5~2 hours.

[0026] Step 2: Using a lathe, the low-density C / C composite material obtained in Step 1 is machined into irregularly shaped samples according to the model drawings, and then cleaned and dried with anhydrous ethanol to obtain irregularly shaped C / C composite materials.

[0027] Step 3: The irregularly shaped C / C composite material obtained in Step 2 is embedded in the alloy powder and placed in a graphite crucible. It is thoroughly compacted to ensure full contact between the alloy powder and the irregularly shaped C / C composite material. The crucible is then placed in the constant temperature zone of a vacuum heat treatment furnace under high temperature and negative pressure conditions to perform an RMI process, introducing an ultra-high temperature ceramic modified phase to obtain a matrix-modified irregularly shaped C / C composite material. The surface of the matrix-modified irregularly shaped C / C composite material is then polished with silicon carbide sandpaper or a diamond file to remove any remaining unreacted alloy powder. Subsequently, it is ultrasonicated in anhydrous ethanol for 5–10 min and dried in an electric heating drying oven at 70–90 °C for 0.5–2 hours. The crucible used in the MI process is made of high-purity graphite. The placement orientation of the low-density irregularly shaped C / C composite material in the graphite crucible is controlled so that the trapezoidal side is perpendicular to the bottom surface of the graphite crucible. The RMI process temperature is 1600–2000 °C, and the furnace pressure is 6–10 Pa.

[0028] Step 4: Using SAPS with ZrC-ZrSi2-B4C powder as raw material, prepare an ultra-high temperature ceramic coating on the trapezoidal side and sharp bevel of the matrix-modified irregular C / C composite material prepared above. Place the coating-matrix-modified irregular C / C composite material obtained after spraying in anhydrous ethanol for ultrasonic cleaning for 10 min, and dry it in an electric heating drying oven at 70~90 ℃ for 0.5~2 hours. The SAPS process uses Ar and H2 as excitation gases, with Ar pressure and flow rate of 1.05–1.35 MPa and 65–75 L / min, respectively, and H2 pressure and flow rate of 1.10–1.20 MPa and 1–3 L / min, respectively. The plasma excitation power is 45–50 kW. The ultra-high temperature ceramic coating is composed of ZrC, ZrSi2, and B4C, with ZrC, ZrSi2, and B4C accounting for 50–70%, 20%–30%, and 10%–20% of the mass of the ultra-high temperature ceramic coating, respectively. The thickness of the ZrC-ZrSi2-B4C coating is 150–250 μm.

[0029] Step 5: Place the coating-matrix modified irregular C / C composite material obtained in Step 4 in the constant temperature zone of the CVD furnace. Under high temperature and negative pressure, prepare a SiC sealing coating on the surface of the coating-matrix modified irregular C / C composite material to achieve surface sealing and densification, thereby obtaining the long-life ablation-resistant irregular C / C composite material of the present invention. The chemical vapor deposition (CVD) process is used, the deposition temperature is 1100 ℃~1300 ℃, trimethylsilane (MTS) is used as the silicon-based precursor, the CVD cycle is 3~5 hours, and the thickness of the SiC sealing coating is 100~200 μm.

[0030] The implementation process of the present invention will be described in detail below with reference to specific embodiments.

[0031] In the following examples and comparative examples, all raw materials used are common commercially available products that can be purchased directly or can be prepared using conventional techniques in the field.

[0032] I. Examples of the preparation method of the long-life, ablation-resistant irregular C / C composite material of the present invention Example 1 The preparation method of the long-life, ablation-resistant irregular C / C composite material in Example 1 includes the following steps: Step 1: A three-dimensional carbon fiber preform was prepared using a puncture process. The preform was then placed in the isothermal zone of an isothermal chemical vapor deposition furnace for pyrolytic carbon deposition densification. Subsequently, the densified preform was placed in a high-temperature graphitization furnace for graphitization treatment at 2000 °C for 2.0 hours, yielding a density of 1.35 g / cm³. 3 C / C composite preform.

[0033] Step 2: Fix the C / C composite material blank obtained in step (1) onto the lathe worktable, and machine the C / C composite material blank into an irregular shape by turning. Manually grind away the residual fibers at the edges of the irregular C / C composite material. Place the ground irregular C / C composite material in anhydrous ethanol for ultrasonic cleaning for 10 min to remove the graphite debris and oil residues left during the machining process. Then place the sample in an electric heating drying oven at 70 ℃ for 2 hours to dry.

[0034] Step 3: Place the fully dried irregularly shaped C / C composite material in a graphite crucible, ensuring the trapezoidal side of the sample is perpendicular to the bottom of the crucible. Fill the crucible with ZrSi2 powder of 99.9% purity and a particle size of 10-30 μm, and manually compact it to ensure close contact between the ZrSi2 powder and the C / C cylinder. Place the crucible in the isothermal zone of a vacuum heat treatment furnace for RMI (Reactive Motion Injection) process. Evacuate to 6 Pa, then raise the temperature of the isothermal zone to 1800 °C at a heating rate of 5 °C / min and hold for 2 hours. After that, slowly cool the crucible with the furnace. During the reaction and infiltration process, the vacuum pump must be continuously running to maintain a vacuum environment. After the RMI process is completed, remove the sample from the crucible and manually grind away any unreacted ZrSi2 powder adhering to the sample surface to obtain the ultra-high temperature ceramic ZrC-SiC modified irregularly shaped C / C composite material. The ZrC-SiC modified shaped C / C composite material (C / C-ZrC-SiC) was ultrasonically cleaned for 10 min with anhydrous ethanol and dried in an electric heating drying oven at 70 °C for 2 hours.

[0035] Step 4: The ZrC-SiC modified irregular C / C-ZrC-SiC composite material was fixed on a thermal spraying test bench. Using a SAPS device, ZrC-ZrSi2-B4C coatings were sequentially applied to the two trapezoidal surfaces and the leading edge of the sample. The mass percentages of HfC, ZrSi2, and B4C in the coatings were 70%, 20%, and 10%, respectively. The Ar gas flow rate and pressure used in the thermal spraying process were 70 L / min and 1.35 MPa, respectively, and the H2 gas flow rate and pressure were 3 L / min and 1.15 MPa, respectively. The spraying power was set to 50 kW, and the coating thickness was 150 μm. After spraying, the sample with the coating was ultrasonically cleaned in anhydrous ethanol for 10 min and dried in a 70 ℃ electric heating oven for 2 hours to obtain the coating-matrix modified irregular C / C-ZrC-SiC composite material.

[0036] Step 5: The coating-matrix modified irregular C / C-ZrC-SiC composite material is placed in the isothermal zone of a chemical vapor deposition furnace. The vacuum is then reduced to 5 kPa, and the temperature is increased to 1100 °C at a rate of 5 °C / min. MTS and H2 are introduced for deposition for 5 hours to form a 150 μm thick SiC sealing coating. After cooling to room temperature, the long-life, ablation-resistant irregular C / C composite material is prepared, yielding the desired result. Figure 1 The long-life, ablation-resistant, irregularly shaped C / C composite material shown is prepared by including a C / C-ZrC-SiC modified phase in the matrix, a ZrC-ZrSi2-B4C coating outside the matrix, and a SiC sealing coating outside the ZrC-ZrSi2-B4C coating. The final density of the long-life, ablation-resistant, irregularly shaped C / C composite material prepared in this example is 2.91 g / cm³. 3 .

[0037] Example 2 The preparation method of the long-life, ablation-resistant irregular C / C composite material in Example 2 includes the following steps: Step 1: A three-dimensional carbon fiber preform was prepared using a puncture process. The preform was then placed in the isothermal zone of an isothermal chemical vapor deposition furnace for pyrolytic carbon deposition densification. Subsequently, the densified preform was placed in a high-temperature graphitization furnace for graphitization treatment at 2200℃ for 1.0 hour to obtain a density of 1.30 g / cm³. 3 C / C composite preform.

[0038] Step 2: Fix the C / C composite preform obtained in step (1) onto the lathe worktable and machine the C / C composite preform into an irregular shape by turning. Manually grind away the residual fibers from machining at the edges of the irregular C / C composite. Place the ground irregular C / C composite in anhydrous ethanol for ultrasonic cleaning for 8 min to remove graphite debris and oil residue from the machining process. Then place the sample in an 80 ℃ electric heating drying oven for drying for 1 hour.

[0039] Step 3: Place the fully dried irregularly shaped C / C composite material in a graphite crucible, ensuring the trapezoidal side of the sample is perpendicular to the bottom of the crucible. Fill the crucible with ZrSi2 powder of 99.9% purity and a particle size of 10-30 μm, and manually compact it to ensure close contact between the ZrSi2 powder and the C / C cylinder. Place the crucible in the isothermal zone of a vacuum heat treatment furnace for RMI (Reactive Motion Injection) process. Evacuate to 8 Pa, then raise the temperature of the isothermal zone to 1600 °C at a heating rate of 5 °C / min and hold for 2 hours. After that, slowly cool the crucible with the furnace. During the reaction and infiltration process, the vacuum pump must be continuously running to maintain a vacuum environment. After the RMI process is completed, remove the sample from the crucible and manually grind away any unreacted ZrSi2 powder adhering to the sample surface to obtain the ultra-high temperature ceramic ZrC-SiC modified irregularly shaped C / C composite material. The ZrC-SiC modified shaped C / C composite material (C / C-ZrC-SiC) was ultrasonically cleaned for 6 min with anhydrous ethanol and dried in an electric heating oven at 70 °C for 2 hours.

[0040] Step 4: The ZrC-SiC modified irregular C / C-ZrC-SiC composite material was fixed on a thermal spraying test bench. Using a SAPS device, ZrC-ZrSi2-B4C coatings were sequentially applied to the two trapezoidal surfaces and the leading edge of the sample. The mass percentages of ZrC, ZrSi2, and B4C in the coatings were 60%, 20%, and 20%, respectively. The Ar gas flow rate and pressure used in the thermal spraying process were 75 L / min and 1.25 MPa, respectively, and the H2 gas flow rate and pressure were 2 L / min and 1.15 MPa, respectively. The spraying power was set to 45 kW, and the coating thickness was 250 μm. After spraying, the sample with the coating was ultrasonically cleaned in anhydrous ethanol for 6 min and dried in an 80℃ electric heating oven for 1 hour to obtain the coating-matrix modified irregular C / C-ZrC-SiC composite material.

[0041] Step 5: The obtained coating-matrix modified irregular C / C-ZrC-SiC composite material was placed in the isothermal zone of a chemical vapor deposition furnace. The vacuum was then reduced to 5 kPa, and the temperature was increased to 1200 °C at a rate of 5 °C / min. MTS and H2 were introduced for deposition for 3 hours to form a 100 μm thick SiC coating. After cooling to room temperature, the long-life, ablation-resistant irregular C / C composite material was successfully prepared. The final density of the long-life, ablation-resistant irregular C / C composite material prepared in this embodiment was 2.85 g / cm³. 3 .

[0042] Example 3 The preparation method of the long-life, ablation-resistant irregular C / C composite material in Example 3 includes the following steps: Step 1: A three-dimensional carbon fiber preform was prepared using a puncture process. The preform was then placed in the isothermal zone of an isothermal chemical vapor deposition furnace for pyrolytic carbon deposition densification. Subsequently, the densified preform was placed in a high-temperature graphitization furnace for graphitization treatment at 2400 °C for 0.5 hours to obtain a density of 1.25 g / cm³. 3 C / C composite preform.

[0043] Step 2: Fix the C / C composite preform obtained in step (1) onto the lathe worktable and machine the C / C composite preform into an irregular shape by turning. Manually grind away the residual fibers from machining at the edges of the irregular C / C composite. Place the ground irregular C / C composite in anhydrous ethanol for ultrasonic cleaning for 10 min to remove graphite debris and oil residue from the machining process. Then place the sample in a 90 ℃ electric heating drying oven for drying for 0.5 hours.

[0044] Step 3: Place the fully dried irregularly shaped C / C composite material in a graphite crucible, ensuring the trapezoidal side of the sample is perpendicular to the bottom of the crucible. Fill the crucible with 99.9% pure HfSi2 powder with a particle size of 10-50 μm, and manually compact it to ensure close contact between the HfSi2 powder and the C / C cylinder. Place the crucible in the isothermal zone of a vacuum heat treatment furnace for RMI (Reactive Motion Injection) process. Evacuate to 8 Pa, then raise the temperature of the isothermal zone to 2000 °C at a heating rate of 5 °C / min and hold for 2 hours. After that, slowly cool the crucible with the furnace. During the reaction and infiltration process, the vacuum pump must run continuously to maintain a vacuum environment. After the RMI process is completed, remove the sample from the crucible and manually grind away any unreacted HfSi2 powder adhering to the sample surface to obtain the ultra-high temperature ceramic HfC-SiC modified irregularly shaped C / C composite material. The HfC-SiC modified shaped C / C composite material (C / C-HfC-SiC) was ultrasonically cleaned for 10 min with anhydrous ethanol and dried in an electric heating drying oven at 90 °C for 0.5 h.

[0045] Step 4: The HfC-SiC modified irregular C / C-HfC-SiC composite material was fixed on a thermal spraying test bench. ZrC-ZrSi2-B4C coatings were sequentially applied to the two trapezoidal surfaces and the leading edge of the sample using SAPS equipment. The mass percentages of ZrC, ZrSi2, and B4C in the coatings were 50%, 30%, and 20%, respectively. The Ar gas flow rate and pressure used in the thermal spraying process were 65 L / min and 1.05 MPa, and the H2 gas flow rate and pressure were 1 L / min and 1.10 MPa, respectively. The spraying power was set to 45 kW, and the coating thickness was 200 μm. After spraying, the coated sample was ultrasonically cleaned in anhydrous ethanol for 6 min and dried in a 90℃ electric heating oven for 0.5 hours to obtain the coating-matrix modified irregular C / C-HfC-SiC composite material.

[0046] Step 5: The obtained coating-matrix modified irregular C / C-HfC-SiC composite material was placed in the isothermal zone of a chemical vapor deposition furnace. The vacuum was then reduced to 5 kPa, and the temperature was increased to 1300 °C at a rate of 5 °C / min. MTS and H2 were introduced for deposition over 4 hours to form a 200 μm thick SiC coating. After cooling to room temperature, the long-life, ablation-resistant irregular C / C composite material was successfully prepared. The final density of the long-life, ablation-resistant irregular C / C composite material prepared in this embodiment was 2.79 g / cm³. 3 .

[0047] II. Experimental Examples 1. Macroscopic morphology inspection of irregularly shaped C / C composite materials The macroscopic morphology of the long-life, ablation-resistant, irregularly shaped C / C composite materials prepared in Examples 1-3 was examined, such as... Figure 2 As shown, due to differences in matrix modification and coating preparation processes, the surface morphology of the long-life ablation-resistant irregular C / C composite materials prepared in the three embodiments of the present invention are slightly different.

[0048] 2. Detection of long-term cyclic ablation process The macroscopic morphology of the long-life, ablation-resistant irregular C / C composite material prepared in Example 1 was detected by long-term cyclic ablation process, such as... Figure 3 As shown in the figure. To simulate the service behavior of the irregular structure, cyclic ablation tests were conducted in three attitudes. Each ablation cycle included three ablation locations, as shown in the figure. Figure 4 As shown, a single location was ablated for 100 s, and a total of 300 s was performed at three locations sequentially to complete one ablation cycle. A long-term cyclic ablation test was used to test the macroscopic morphology of the long-life, ablation-resistant irregular C / C composite material prepared in Example 1 for seven ablation cycles (cumulative ablation time 2100 s). It can be seen that after the ablation test begins, the plasma flame torch is initially positioned vertically to the leading edge for ablation (…). Figure 4 a). After 100 seconds of ablation, the plasma flame torch is rapidly rotated 30° and moved to the front end of the trapezoidal side of the irregular C / C composite material for another 100 seconds of ablation. Figure 4 b), finally, the ion flame torch rotates rapidly by 15° and moves to the middle of the trapezoidal side of the irregular C / C composite material for 100 seconds of ablation. Figure 4 c). After the ablation at the three locations is completed, the plasma flame torch is returned to the original working point and extinguished for cooling, thus completing one cycle of ablation testing. After the sample cools to room temperature, the surface macromorphology and ablation rate are detected.

[0049] 3. Surface macroscopic morphology inspection after different ablation cycles The macroscopic morphology of the long-life, ablation-resistant irregular C / C composite material prepared in Example 1 was examined after different ablation cycles. For example... Figure 5 As shown, the area of ​​the white oxide region on the surface of the long-life, ablation-resistant irregular C / C composite material gradually expands with the extension of ablation time, indicating that the ZrC-ZrSi2-B4C / SiC coating on the sample surface is gradually oxidized to form an oxide film. During the ablation process, the oxide film structure remains intact, without catastrophic cracking or peeling. After 2100 s of ablation, the mass ablation rate and linear ablation rate of the sample are as low as 0.397 mg / s and -0.271 μm / s, respectively, exhibiting excellent ablation resistance.

[0050] 4. SEM detection SEM images of the cross-section of the long-life, ablation-resistant irregular C / C composite material prepared in Example 1 after 2100 s of ablation are shown below. Figure 6 As shown, the microstructure of the coating remained intact after ablation without large-scale peeling. Figure 6 Magnified observation of part b reveals that the outer SiC coating cracks under the thermal coupling scouring of the ablation flame. Oxygen penetrates into the inner ZrC-ZrSi2-B4C coating through these cracks, leading to high-temperature oxidation and the formation of an oxide film. The in-situ generated oxide film can prevent further penetration of oxidation into the C / C-ZrC-SiC matrix, achieving long-life anti-oxidation and ablation protection.

[0051] This demonstrates that the long-life, ablation-resistant, irregularly shaped C / C composite material provided in this application not only ensures oxidation and ablation resistance but also possesses low density and ultra-high temperature tolerance. It exhibits excellent long-life ablation resistance and is suitable for long-term ultra-high temperature oxidation and ablation environments at 2500℃. Compared with existing ceramic coating protection technologies for refractory alloy aerospace hot-end components, it effectively solves the challenges of lightweight design and insufficient high-temperature reliability.

[0052] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a long-life, ablation-resistant irregularly shaped C / C composite material, characterized in that, Includes the following steps: (1) Process the low-density C / C composite material into an irregular shape containing trapezoidal sides and sharp bevels to obtain an irregular C / C composite material; (2) The irregular C / C composite material is placed in alloy powder for melt infiltration reaction to introduce ultra-high temperature ceramic modified phase, so as to obtain matrix modified irregular C / C composite material; (3) Prepare ultra-high temperature ceramic coatings on the trapezoidal side surface and sharp bevel of the matrix-modified irregular C / C composite material to obtain the coating-matrix modified irregular C / C composite material; (4) A SiC sealing coating is deposited on the surface of the coating-matrix modified irregular C / C composite material to obtain a long-life ablation resistant irregular C / C composite material.

2. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 1, characterized in that, In step (3), the ultra-high temperature ceramic coating is composed of three ultra-high temperature ceramics: ZrC, ZrSi2, and B4C; the mass percentages of ZrC, ZrSi2, and B4C in the ultra-high temperature ceramic coating are 50-70%, 20-30%, and 10-20%, respectively.

3. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 1, characterized in that, The thickness of the ultra-high temperature ceramic coating is 150~250 μm, and the thickness of the SiC sealing coating is 100~200 μm.

4. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 1, characterized in that, In step (3), the preparation of the ultra-high temperature ceramic coating adopts supersonic atmospheric plasma spraying technology. The process parameters of the supersonic atmospheric plasma spraying technology are as follows: the excitation gas of the plasma is Ar and H2, the pressure and flow rate of Ar are 1.05~1.35 MPa and 65~75 L / min respectively, the pressure and flow rate of H2 are 1.10~1.20 MPa and 1~3 L / min respectively, and the excitation power of the plasma is 45~50 kW.

5. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 1, characterized in that, The preparation method of the low-density C / C composite material includes the following steps: Pyrolytic carbon is deposited on a carbon fiber preform to obtain a matrix C / C composite material; the matrix C / C composite material is then graphitized to obtain a low-density C / C composite material.

6. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 5, characterized in that, The graphitization treatment temperature is 2000~2400 ℃, the graphitization treatment atmosphere is Ar, and the graphitization treatment time is 0.5~2 hours.

7. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 5, characterized in that, The density of the matrix C / C composite material is 1.30~1.40 g / cm³. 3 The density of the low-density C / C composite material is 1.25~1.35 g / cm³. 3 .

8. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 1, characterized in that, In step (2), the alloy powder is MSi2, M is Hf, Zr, Ti or Ta, the purity of the powder alloy powder is 99.9%, and the particle size is 10~50μm.

9. The method for preparing the long-life, ablation-resistant irregular C / C composite material according to claim 1, characterized in that, The process includes the following after step (3): The coating-matrix modified irregular C / C composite material is cleaned and dried. The drying process is carried out at a temperature of 70~90 ℃ for 0.5~2 hours.

10. A long-life, ablation-resistant, irregularly shaped C / C composite material prepared by any one of claims 1 to 9, wherein the long-life, ablation-resistant, irregularly shaped C / C composite material is a columnar structure having trapezoidal sides and sharp bevels.

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