Lightweight ablation-resistant ultra-high-temperature ceramic matrix composite material and preparation method thereof

Abstract

The invention provides a lightweight ablation-resistant ultra-high-temperature ceramic matrix composite material and a preparation method thereof, and the preparation method comprises the following steps: sequentially impregnating, curing and cracking a carbon fiber preform deposited with a pyrolytic carbon interface layer by using phenolic resin to obtain a porous low-density C / C base material; the preparation method comprises the following steps: carrying out vacuum embedding reaction infiltration on a porous low-density C / C base material by utilizing silicon-zirconium or silicon-hafnium binary alloy powder with designed components, and then carrying out surface treatment on the obtained material to obtain the ultrahigh-temperature ceramic-based composite material containing the integrated coating. Wherein the content of a ZrC or HfC ultrahigh-temperature ceramic phase contained in the ultrahigh-temperature ceramic-based composite material in the direction from the outer surface to the interior is gradually reduced, and the content of a SiC ceramic phase is gradually increased; and modifying the integrated coating on the surface of the material by using a CVI-SiC process to obtain the lightweight ablation-resistant ultrahigh-temperature ceramic-based composite material. The ultrahigh-temperature ceramic-based composite material disclosed by the invention has excellent oxidation ablation resistance on the basis of light weight.

Description

Technical Field

[0001] This invention relates to the field of ultra-high temperature ceramic matrix composites, and particularly to a lightweight ablation-resistant ultra-high temperature ceramic matrix composite and its preparation method. Background Technology

[0002] C / C composites possess advantages such as low density, low coefficient of thermal expansion, high hardness, high specific strength, high specific modulus, and excellent chemical stability, making them widely used in the thermal structure and thermal protection systems of aerospace vehicles. However, C / C composites oxidize in aerobic environments above 400℃, significantly limiting their application in such conditions. Matrix modification techniques can introduce ceramic components with anti-oxidation and ablation properties, such as SiC, ZrC, HfC, TaC, ZrB2, HfB2, and TaB2, into C / C composites, thereby greatly improving their performance.

[0003] As a key ablation-resistant ceramic component, ZrC (density 12.8 g / cm³) 3 ) and HfC (density 6.6 g / cm³) 3 Although it possesses excellent ultra-high temperature resistance and ablation resistance, its density is much higher than that of the commonly used ceramic component SiC (density 3.2 g / cm³). 3 This high density significantly increases the overall weight of composite materials, making it difficult to meet stringent lightweight requirements. However, reducing the ZrC or HfC content in composite materials to reduce weight inevitably weakens their crucial oxidation and ablation resistance. Therefore, achieving a breakthrough balance between high performance (excellent oxidation and ablation resistance) and low density (lightweighting) is a critical technical challenge that urgently needs to be overcome in the field of ultra-high temperature ceramic matrix composites.

[0004] Therefore, there is an urgent need to provide a lightweight, ablation-resistant, ultra-high temperature ceramic matrix composite material and its preparation method. Summary of the Invention

[0005] This invention provides a lightweight, ablation-resistant, ultra-high temperature ceramic matrix composite material and its preparation method, which can solve the problem that traditional ceramic matrix composite materials cannot simultaneously possess good lightweight and oxidation-resistant ablation properties.

[0006] In a first aspect, the present invention provides a method for preparing a lightweight, ablation-resistant, ultra-high temperature ceramic matrix composite material, the method comprising the following steps: (1) A porous low-density C / C substrate was obtained by sequentially impregnating, curing and pyrolyzing a carbon fiber preform with a pyrolytic carbon interface layer using phenolic resin. (2) The porous low-density C / C substrate is embedded and infiltrated in a vacuum using silicon zirconium or silicon hafnium binary alloy powder, and the resulting material is surface treated to obtain an ultra-high temperature ceramic matrix composite material containing an integrated coating; wherein, the content of ZrC or HfC ultra-high temperature ceramic phase in the ultra-high temperature ceramic matrix composite material gradually decreases from the outer surface to the inner direction, and the content of SiC ceramic phase gradually increases. (3) Modify the integrated coating on the surface of the composite material using the CVI-SiC process to obtain the lightweight ablation resistant ultra-high temperature ceramic matrix composite material.

[0007] Preferably, in step (1), the carbon fiber preform is any one of a carbon fiber needle-punched structure, a carbon cloth laminated stitching structure, or a fine-woven puncture structure.

[0008] Preferably, the density of the carbon fiber preform is 0.50~0.80 g / cm³. 3 .

[0009] Preferably, in step (1), a pyrolytic carbon interface layer is deposited on the surface of the carbon fibers in the carbon fiber preform using chemical vapor deposition; wherein, during the vapor deposition process, propylene is used as the carbon source, nitrogen is used as the carrier gas, the deposition temperature is 800~1100℃, and the density increase of the carbon fiber preform after pyrolytic carbon deposition is 0.30~0.50 g / cm³. 3 .

[0010] Preferably, before depositing a pyrolytic carbon interface layer on the carbon fiber surface in the carbon fiber preform, the method further includes a step of high-temperature preheating treatment of the carbon fiber preform; preferably, the temperature of the high-temperature preheating treatment is 1500-2000℃, and the holding time is 2.0-3.0h.

[0011] Preferably, in step (1), the impregnation method is vacuum pressure impregnation; wherein the vacuum degree is 5-100 Pa, the pressure is 0.5-2.0 MPa, the temperature is room temperature, and the time is 0.5-2.0 h; The curing temperature is 100–300℃, the pressure is 0.5–2.5 MPa, and the time is 0.5–2.0 h. The pyrolysis temperature is 700~1000℃, and the time is 2.0~4.0h.

[0012] Preferably, after impregnation, curing, and pyrolysis, the density increment of the carbon fiber preform with the deposited pyrolytic carbon interface layer is 0.30~0.50 g / cm³. 3 .

[0013] Preferably, in step (2), the atomic weight fraction of zirconium in the silicon-zirconium binary alloy powder is 18-23 at.%; and the atomic weight fraction of hafnium in the silicon-hafnium binary alloy powder is 19-28 at.%.

[0014] More preferably, the particle size of the silicon-zirconium or silicon-hafnium binary alloy powder is 1–10 μm.

[0015] Preferably, in step (2), the reaction melting and infiltration is carried out in a vacuum environment at a temperature of 1600~1800℃ and a holding time of 1.0~2.0h.

[0016] Preferably, in step (2), the surface treatment is grinding or cutting.

[0017] Preferably, after surface treatment, the thickness of the integrated coating is 100~200μm.

[0018] Preferably, in step (3), when modifying using the CVI-SiC process, the raw material used is methyltrichlorosilane, and the hydrogen flow rate is 0.25~0.60 m³ / h. 3 / h, argon flow rate is 0.40~1.00m³ / h. 3 The deposition rate is 950~1150℃, and the deposition time is 10~30h.

[0019] Preferably, in step (3), the thickness of the SiC coating formed after modification is 10~30μm.

[0020] In a second aspect, the present invention also provides a lightweight ablation-resistant ultra-high temperature ceramic matrix composite material prepared by the preparation method described in any one of the first aspects above.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: (1) In this invention, firstly, silicon zirconium or silicon hafnium binary alloy powder with specific composition is used to embed and melt infiltrate a porous low-density C / C substrate, and at the same time, an ultra-high temperature ceramic integrated coating is generated in situ. The resulting ceramic matrix composite material has a high proportion of low-density ceramic components (SiC) in the internal matrix, which helps to achieve material lightweighting. The external matrix has a high proportion of ultra-high temperature ceramic components (ZrC or HfC), and an integrated coating with ultra-high temperature ceramics (ZrC or HfC) as the main component is generated in situ on the surface of the matrix. Secondly, the integrated coating on the surface of the material is modified by CVI-SiC process to form a ZrC (or HfC) and SiC multiphase coating. During the oxidation and ablation process, ZrC or HfC is oxidized to generate HfO2 or ZrO2 porous skeleton. SiO2 melt fills its pores, which can effectively block oxygen in the atmosphere from diffusing into the material. The ultra-high temperature ceramic components and SiC work together to make the material exhibit good oxidation and ablation resistance in the oxidation and ablation environment. Thus, the ultra-high temperature ceramic matrix composite material prepared by this invention not only has lightweight properties but also excellent resistance to oxidation and ablation, which can meet the usage requirements of thermal structures, thermal protection systems and other components of aircraft in the aerospace field.

[0022] (2) In this invention, the RMI process is used to perform vacuum embedding reaction melting infiltration on a porous low-density C / C substrate. The resulting material is then surface-treated, and the integrated coating on the material surface is further modified using the CVI-SiC process. This method can improve the oxidation and ablation resistance of the integrated coating through a ZrC (or HfC) and SiC multiphase coating without affecting the mechanical properties of the substrate material. Furthermore, compared to the traditional PIP and CVI processes, the RMI process can significantly shorten the preparation cycle and reduce production costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a partial backscattered scanning electron microscope image of an ultra-high temperature ceramic matrix composite material containing an integrated coating during the preparation of a lightweight ablation-resistant ultra-high temperature ceramic matrix composite material provided in Embodiment 1 of the present invention; Figure 2The graphs show the process curves of the lightweight ablation-resistant ultra-high temperature ceramic matrix composite material and the ultra-high temperature ceramic matrix composite material with an integrated coating without CVI-SiC modification provided in Example 1 and Comparative Example 1 of this invention after a 300s oxyacetylene ablation test. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] As mentioned earlier, ceramic matrix composites in related technologies typically cannot simultaneously possess lightweight, excellent oxidation and ablation resistance, and mechanical properties. For example, the literature "Sijie Kou, Shangwu Fan, Xu Ma, et al. Ablation performance of C / HfC-SiC composites with in-situ HfSi2 / HfC / SiC multi-phase coatings under 3000℃ oxyacetylene torch[J]. Corrosion Science, 2022, 200:110218." describes the preparation of C / C-HfC-SiC composites and their integrated HfSi2 / HfC / SiC coating using a reactive melting infiltration method with hafnium silicon alloy powder. The high HfC content in this coating results in an overly homogeneous ceramic phase. Although both Hf carbides (HfC melting point 3900℃) and oxides (HfO2 melting point 2758℃) have high melting points, their oxidation product HfO2 has a high sintering temperature (above 1900℃). Below this temperature, HfO2 fails to sinter sufficiently and becomes porous, making it prone to detachment and thus affecting the protective effect of the coating.

[0027] For example, the literature “Zhiqiang Liu, Qiangang Fu, Huilun Shi, et al. Comparative study of microstructure and ablation behavior of C / C-HfC-SiC composites prepared under two different conditions[J]. Materials Characterization, 2022,194: 112467” describes the preparation of C / C-HfC-SiC composites and their integrated coatings with different components on their surfaces (HfC and HfSi2 / HfC / SiC, respectively) using two different atmospheres (vacuum and argon). Compared with a single HfC coating, the HfSi2 / HfC / SiC composite coating, due to the presence of low-melting-point HfSi2, can improve the density of the loose HfO2 oxide film during ablation, thus exhibiting better protective effects than a single HfC coating; however, HfSi2 itself has a low melting point and is prone to rapid evaporation during high-temperature ablation, resulting in a larger ablation amount.

[0028] For example, the literature “Zhiqiang Liu, Yujun Jia, Jiaqi Hou, et al. C / C-HfC-SiC composites with simultaneous resistance to ultrahigh temperature airflowerosion and high temperature oxidation[J]. Journal of Materiomics, 2025, 11:100846.” and “Zhiqiang Liu, Shubo Zhang, Jiaping Zhang, et al. Effect of gaseous silicon infiltration process on mechanical and ablation properties of C / C-HfC-SiC composites with HfSi2 / HfC coating prepared by reactive meltinfiltration[J]. Composites Communications” used a method combining reactive melt infiltration of silicon hafnium alloy powder and Si vapor infiltration to prepare C / C-HfC-SiC composites and surface integrated Si-HfC-HfSi2 coatings and their effects on material properties. Compared to materials without Si vapor infiltration, materials with Si vapor infiltration reduce surface defects, but due to the low melting point of elemental Si, it will be rapidly lost during oxidation and ablation. At the same time, Si vapor infiltration also has a very adverse effect on the mechanical properties of the material.

[0029] To address one or more of the aforementioned problems, embodiments of the present invention provide a method for preparing a lightweight, ablation-resistant, ultra-high temperature ceramic matrix composite material, the method comprising the following steps: (1) A porous low-density C / C substrate was obtained by sequentially impregnating, curing and pyrolyzing a carbon fiber preform with a pyrolytic carbon interface layer using phenolic resin. (2) The porous low-density C / C substrate is embedded and infiltrated in a vacuum using silicon zirconium or silicon hafnium binary alloy powder, and the resulting material is surface treated to obtain an ultra-high temperature ceramic matrix composite material containing an integrated coating; wherein, the content of ZrC or HfC ultra-high temperature ceramic phase in the ultra-high temperature ceramic matrix composite material gradually decreases from the outer surface to the inner direction, and the content of SiC ceramic phase gradually increases. (3) Modify the integrated coating on the surface of the composite material using the CVI-SiC process to obtain the lightweight ablation resistant ultra-high temperature ceramic matrix composite material.

[0030] In this embodiment of the invention, firstly, a porous low-density C / C substrate is embedded and infiltrated with silicon-zirconium or silicon-hafnium binary alloy powder of a specific composition, while simultaneously generating an integrated ultra-high temperature ceramic coating in situ. The resulting ceramic matrix composite material has a high proportion of low-density ceramic components (SiC) in its internal matrix, which helps to achieve material lightweighting. The external matrix has a high proportion of ultra-high temperature ceramic components (ZrC or HfC), and an integrated coating with ultra-high temperature ceramics (ZrC or HfC) as the main component is generated in situ on the matrix surface. Secondly, through the CVI-SiC coating modification process, a ZrC (or HfC) and SiC multiphase coating can be formed. During the oxidation and ablation process, ZrC or HfC is oxidized to generate HfO2 or ZrO2 porous framework, and SiO2 melt fills its pores, which can effectively block the diffusion of oxygen in the atmosphere into the material interior. The ultra-high temperature ceramic components and SiC work synergistically to improve its oxidation and ablation resistance. Furthermore, considering the material properties, the thermal conductivity of ZrC, HfC, and SiC are 20.61 W / (m·K), 22.2 W / (m·K), and (120~270) W / (m·K), respectively. The oxidation Gibbs free energy of ZrC and HfC is lower than that of SiC, thus preferentially oxidizing to form ZrO2 and HfO2 during ablation. Meanwhile, the infrared emissivity of ZrO2 and HfO2 is (0.62~0.75) and 0.621, respectively, lower than that of SiC and SiO2 (emissivity ≥0.80). Therefore, increasing the SiC content in the coating helps to reduce the ablation surface temperature. Through synergistic control of various aspects, the ultra-high temperature ceramic matrix composite material prepared in this invention possesses excellent oxidation and ablation resistance while maintaining lightweight properties, meeting the requirements for thermal structures and thermal protection systems in aerospace vehicles.

[0031] According to some preferred embodiments, in step (1), the carbon fiber preform is any one of a carbon fiber needle-punched structure, a carbon cloth laminated stitching structure, or a fine-woven puncture structure; the density of the carbon fiber preform is 0.50~0.80 g / cm³. 3 (For example, it can be 0.50 g / cm) 3 0.60g / cm 3 0.70g / cm 3 Or 0.80g / cm 3 ).

[0032] According to some preferred embodiments, in step (1), a pyrolytic carbon interface layer is deposited on the surface of the carbon fibers in the carbon fiber preform using chemical vapor deposition; wherein, during the vapor deposition process, propylene is used as the carbon source, nitrogen is used as the carrier gas, and the deposition temperature is 800~1100℃ (for example, 800℃, 900℃, 1000℃ or 1100℃), and the density increase of the carbon fiber preform after pyrolytic carbon deposition is 0.30~0.50 g / cm³. 3 (For example, it can be 0.30 g / cm³) 3 0.40 g / cm 3 0.45g / cm 3 Or 0.50g / cm 3 Before depositing a pyrolytic carbon interface layer on the carbon fiber surface in the carbon fiber preform, the process further includes a high-temperature preheating treatment of the carbon fiber preform; the temperature of the high-temperature preheating treatment is 1500-2000℃ (for example, it can be 1500℃, 1600℃, 1800℃ or 2000℃), and the holding time is 2.0-3.0h (for example, it can be 2.0h, 2.2h, 2.5h, 2.8h or 3.0h).

[0033] In this embodiment of the invention, before depositing a pyrolytic carbon interface layer on the surface of the carbon fibers in the carbon fiber preform, the carbon fiber preform is first preheated at a high temperature, which is beneficial for the subsequent formation of a uniform and dense pyrolytic carbon interface layer on the surface of the carbon fiber preform by CVI (chemical vapor deposition) process.

[0034] According to some preferred embodiments, in step (1), the impregnation method is vacuum pressure impregnation; wherein the vacuum degree is 5-100 Pa (e.g., 5 Pa, 10 Pa, 30 Pa, 50 Pa, 80 Pa or 100 Pa), the pressure is 0.5-2.0 MPa (e.g., 0.5 MPa, 1.0 MPa, 1.5 MPa or 2.0 MPa), the temperature is room temperature, and the time is 0.5-2.0 h (e.g., 0.5 h, 1.0 h, 1.5 h or 2.0 h); the curing temperature is 100-300 °C (e.g., 100 °C, 150 °C, 200 °C, 240 °C or 300 °C). The pyrolysis is performed at a temperature of 0°C, a pressure of 0.5–2.5 MPa (e.g., 0.5 MPa, 1.0 MPa, 1.5 MPa, 2.0 MPa, or 2.5 MPa), and a time of 0.5–2.0 h (e.g., 0.5 h, 1.0 h, 1.5 h, or 2.0 h); the pyrolysis temperature is 700–1000°C (e.g., 700°C, 800°C, 900°C, or 1000°C), and the time is 2.0–4.0 h (e.g., 2.0 h, 3.0 h, or 4.0 h); after impregnation, curing, and pyrolysis, the density increment of the carbon fiber preform with the deposited pyrolytic carbon interface layer is 0.30–0.50 g / cm³. 3 (For example, it can be 0.30 g / cm³) 3 0.40 g / cm 3 0.45g / cm 3 Or 0.50g / cm 3 ).

[0035] In this embodiment of the invention, phenolic resin is used to impregnate, cure, and pyrolyze the carbon fiber preform with the deposited pyrolytic carbon interface layer. By synergistically controlling the impregnation, curing, and pyrolysis parameters, the fiber and the matrix can be better bonded together. Furthermore, the phenolic resin is converted into carbon after high-temperature pyrolysis, which can provide a carbon source for subsequent reaction melting and infiltration, thereby forming a ceramic matrix component.

[0036] According to some preferred embodiments, in step (2), the atomic weight fraction of zirconium in the silicon-zirconium binary alloy powder is 18-23 at.% (for example, it can be 18 at.%, 19 at.%, 20 at.%, 21 at.%, 22 at.% or 23 at.%), preferably 20-23 at.%; the atomic weight fraction of hafnium in the silicon-hafnium binary alloy powder is 19-28 at.% (for example, it can be 19 at.%, 20 at.%, 22 at.%, 25 at.% or 28 at.%), preferably 25-28 at.%; the particle size of the silicon-zirconium or silicon-hafnium binary alloy powder is 1-10 μm (for example, it can be 1 μm, 2 μm, 5 μm, 8 μm or 10 μm).

[0037] According to some preferred embodiments, in step (2), the reaction melting and infiltration is carried out in a vacuum environment at a temperature of 1600~1800℃ (for example, it can be 1600℃, 1700℃ or 1800℃) and the holding time is 1.0~2.0h (for example, it can be 1.0h, 1.5h or 2.0h).

[0038] In this embodiment of the invention, silicon-zirconium or silicon-hafnium binary alloy powders of specific types, contents, and particle sizes are used to reactively infiltrate a porous low-density C / C matrix under vacuum and high-temperature conditions. The silicon-zirconium or silicon-hafnium binary alloy powders of the designed composition can melt under vacuum and high-temperature conditions. The molten alloy melt infiltrates into the pores of the porous low-density C / C substrate, thereby reacting with the carbon source in the porous low-density C / C substrate, and subsequently generating SiC and ZrC (or HfC) ceramic phases in situ inside the porous low-density C / C substrate. During the reactive infiltration process, silicon-zirconium binary alloy powder with a zirconium atomic fraction of 18–23 at.% and silicon-hafnium binary alloy powder with a hafnium atomic fraction of 19–28 at.% are selected. The melting behavior is characterized by the eutectic phase melting first, and as the temperature increases, the content of high-melting-point components (Zr or Hf) in the melt gradually increases until complete liquefaction. Under capillary action, the initially molten liquid phase (rich in Si) first penetrates into the porous, low-density C / C matrix, reacting with carbon to form a high-proportion SiC ceramic phase, thus facilitating the lightweighting of the composite material. Meanwhile, the external region becomes increasingly enriched with high-melting-point components, and the Gibbs formation energies of ZrC and HfC at high temperatures are lower than those of SiC (e.g., at 1900℃, the Gibbs formation energy of ZrC is -176.66 kJ·mol⁻¹). -1 The Gibbs formation energy of HfC is -213.74 kJ·mol⁻¹. -1 The Gibbs formation energy of SiC is -42.134 kJ·mol⁻¹. -1 At 1700℃, the Gibbs formation energy of HfC is -215.04 kJ·mol⁻¹. -1 The Gibbs formation energy of SiC is -48.54 kJ·mol⁻¹. -1 Therefore, ultra-high temperature ceramic phases (ZrC or HfC) preferentially form on the surface of the material. At the same time, the Si remaining on the surface in the high temperature vacuum environment is also easy to volatilize, which further promotes the formation of an integrated ultra-high temperature ceramic (ZrC or HfC) coating on the material surface.

[0039] According to some preferred embodiments, in step (2), the surface treatment is grinding or cutting; after the surface treatment, the thickness of the integrated coating is 100~200μm (for example, it can be 100μm, 150μm or 200μm).

[0040] In this embodiment of the invention, after the porous low-density C / C substrate is embedded and infiltrated with silicon zirconium or silicon hafnium binary alloy powder, the surface of the material is further polished or cut to keep the thickness of the integrated coating formed in the ceramic matrix composite material within the above-mentioned range.

[0041] According to some preferred embodiments, in step (3), when modifying using the CVI-SiC process, the raw material used is methyltrichlorosilane, and the hydrogen flow rate is 0.25~0.60m³. 3 / h (for example, it can be 0.25m) 3 / h, 0.30m 3 / h, 0.50m 3 / h or 0.60m 3 / h), argon flow rate is 0.40~1.00m³ / h. 3 / h (for example, it can be 0.40m) 3 / h, 0.50m 3 / h, 0.80m 3 / h or 1.00m 3 The deposition temperature is 950~1150℃ (e.g., 950℃, 980℃, 1000℃, 1100℃ or 1150℃), and the deposition time is 10~30h (e.g., 10h, 20h or 30h).

[0042] According to some preferred embodiments, in step (3), the thickness of the coating formed after CVI-SiC modification is 10~30μm (for example, it can be 10μm, 20μm or 30μm).

[0043] In this embodiment of the invention, the surface of the integrated coating of the ceramic matrix composite material is further modified using the CVI-SiC process. By synergistically controlling various parameters in the CVI-SiC process, a dense SiC coating of a certain thickness is deposited on the surface of the integrated coating. This SiC coating can form an antioxidant barrier, thereby significantly improving the composite material's resistance to oxidation and ablation. Furthermore, the SiC layer can form a multiphase coating with HfC / ZrC, which has good adhesion to the substrate and can effectively avoid the problem of easy detachment of the integrated coating due to its single composition during oxidation and ablation. If the thickness of the SiC coating is too high, the thermal stress of the coating will be large, making it prone to detachment. Conversely, if the thickness of the SiC coating is too low, it will not significantly improve the composite material's resistance to oxidation and ablation.

[0044] In this embodiment of the invention, a reactive infiltration process is used to infiltrate a porous, low-density C / C substrate. After surface treatment, an ultra-high temperature ceramic matrix composite material containing an integrated coating is obtained. Subsequently, the integrated coating on the material surface is further modified using a CVI-SiC process. This method can improve the oxidation and ablation resistance of the integrated coating through a ZrC (or HfC) and SiC multiphase coating without affecting the performance of the matrix material. Furthermore, compared with traditional PIP and CVI processes, the RMI process can significantly shorten the preparation cycle and reduce production costs.

[0045] This invention also provides a lightweight, ablation-resistant, ultra-high temperature ceramic matrix composite material prepared by any of the above-described preparation methods.

[0046] To more clearly illustrate the technical solution and advantages of the present invention, the following detailed description of a lightweight ablation-resistant ultra-high temperature ceramic matrix composite material and its preparation method is provided through several embodiments.

[0047] Example 1: (1) The carbon fiber preform (density 0.50 g / cm³) 3 The woven needle-punched structure was preheated at 1600℃ for 2.0 h, followed by chemical vapor deposition (using propylene as the carbon source, nitrogen as the carrier gas, deposition temperature of 1000℃, and the density of the deposited preform was 1.00 g / cm³). 3 A pyrolytic carbon interface layer is deposited on the carbon fibers in the carbon fiber preform to obtain a carbon fiber preform with a pyrolytic carbon interface layer deposited on it. A carbon fiber preform with a pyrolytic carbon interface layer deposited on it was subjected to vacuum pressure impregnation, curing, and high-temperature pyrolysis using phenolic resin as a precursor, resulting in a preform with a density of 1.40 g / cm³. 3 A porous low-density C / C substrate; wherein, the impregnation vacuum degree is 50Pa, the pressure is 2.0MPa, the temperature is room temperature (25℃), and the time is 1.5h; the curing temperature is 240℃, the pressure is 1.5MPa, and the time is 2.0h; the high-temperature pyrolysis temperature is 800℃, and the time is 2.0h; (2) A porous low-density C / C substrate was embedded with silicon-hafnium binary alloy powder with a particle size of 1-10 μm (hafnium atomic weight fraction of 27 at.% and silicon atomic weight fraction of 73 at.%) and reacted and infiltrated in a vacuum environment at 1700℃ for 1.5 h. Then, the surface was cut to obtain an ultra-high temperature ceramic matrix composite material with an integrated coating (integrated coating thickness of 150 μm). The content of ZrC or HfC ultra-high temperature ceramic phase in the ultra-high temperature ceramic matrix composite material gradually decreased from the outer surface to the inner surface, while the content of SiC ceramic phase gradually increased. (3) Using methyltrichlorosilane as raw material, chemical vapor deposition process (H2 gas flow rate of 0.35m) was employed. 3 / h, Ar gas flow rate is 0.60m 3 The surface of an ultra-high temperature ceramic matrix composite material containing an integrated coating was modified with SiC (the thickness of the SiC coating formed was 20 μm) at a deposition temperature of 1100℃ and a time of 15 h to obtain a lightweight ablation-resistant ultra-high temperature ceramic matrix composite material.

[0048] The lightweight, ablation-resistant, ultra-high temperature ceramic matrix composite material obtained in this embodiment has a tensile strength of 111 MPa and a flexural strength of 187 MPa, as tested. Figure 2 As shown, the ultra-high temperature ceramic matrix composite material with an integrated coating in Comparative Example 1 and the lightweight ablation-resistant ultra-high temperature ceramic matrix composite material in Example 1, without CVI-SiC modification, were evaluated using the same oxyacetylene parameters. The linear ablation rates were 6.8 × 10⁻⁶ and 6.8 × 10⁻⁶, respectively. -4 mm / s and 5.6×10 -4 The ablation speed was mm / s, and the equilibrium temperatures of the ablation surfaces were 2060℃ and 1700℃, respectively.

[0049] Example 2: (1) The carbon fiber preform (density 0.50 g / cm³) 3 The woven needle-punched structure was preheated at 1700℃ for 2.0 h, followed by chemical vapor deposition (using propylene as the carbon source, nitrogen as the carrier gas, and a deposition temperature of 1000℃, resulting in a preform density of 0.95 g / cm³). 3 A pyrolytic carbon interface layer is deposited on the carbon fibers in the carbon fiber preform to obtain a carbon fiber preform with a pyrolytic carbon interface layer deposited on it. A carbon fiber preform with a pyrolytic carbon interface layer deposited on it was subjected to vacuum pressure impregnation, curing, and high-temperature pyrolysis using phenolic resin as a precursor, resulting in a preform with a density of 1.35 g / cm³. 3 A porous low-density C / C substrate; wherein, the impregnation vacuum degree is 80Pa, the pressure is 2.0MPa, the temperature is room temperature (25℃), and the time is 1.5h; the curing temperature is 240℃, the pressure is 1.5MPa, and the time is 2.0h; the high-temperature pyrolysis temperature is 800℃, and the time is 2.0h; (2) A porous low-density C / C substrate was embedded with silicon-zirconium binary alloy powder with a particle size of 1-10 μm (zirconium atomic weight fraction of 22 at.% and silicon atomic weight fraction of 78 at.%) and reacted and infiltrated at 1700℃ in a vacuum environment for 1.5 h. Then, the surface was cut to obtain an ultra-high temperature ceramic matrix composite material with an integrated coating (integrated coating thickness of 150 μm). The content of ZrC or HfC ultra-high temperature ceramic phase in the ultra-high temperature ceramic matrix composite material gradually decreased from the outer surface to the inner surface, while the content of SiC ceramic phase gradually increased. (3) Using methyltrichlorosilane as raw material, chemical vapor deposition process (H2 gas flow rate of 0.38 m) was employed. 3 / h, Ar gas flow rate is 0.65m³ / h. 3 The surface of an ultra-high temperature ceramic matrix composite material containing an integrated coating was modified with SiC (the thickness of the SiC coating formed was 20 μm) at a deposition temperature of 1100℃ and a time of 15 h to obtain a lightweight ablation-resistant ultra-high temperature ceramic matrix composite material.

[0050] Comparative Example 1: Comparative Example 1 is basically the same as Example 1, except that step (3) is omitted, that is, the surface of the integrated coated ceramic matrix composite material is not modified with SiC.

[0051] Comparative Example 2: Comparative Example 2 is basically the same as Example 1, except that before step (3), it also includes the step of depositing a 30 μm pyrolytic carbon interface layer on the surface of the integrated coated ceramic matrix composite material by chemical vapor deposition.

[0052] The lightweight ablation-resistant ultra-high temperature ceramic matrix composites (hereinafter referred to as ceramic matrix composites) prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to performance tests, and the test results are shown in Table 1. Test standards: Tensile strength test standard: GJB 8736-2015 "Test method for tensile properties of continuous fiber reinforced ceramic matrix composites at room temperature", flexural strength test standard: Q / SB 513-2013 "Test method for flexural properties of continuous fiber reinforced ceramic matrix composites at room temperature", linear ablation rate test standard: GJB 323B-2018 "Test method for ablation of ablation materials".

[0053] Table 1 As shown in Table 1, compared with the comparative example, the ultra-high temperature ceramic matrix composite material prepared in the embodiments of the present invention has excellent anti-oxidation and ablation properties while being lightweight.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a lightweight ablation-resistant ultrahigh-temperature ceramic matrix composite, characterized in that, The preparation method comprises the following steps: (1) using phenolic resin to sequentially perform impregnation, curing and pyrolysis on a carbon fiber preform having a pyrolytic carbon interface layer deposited thereon, to obtain a porous low-density C / C substrate; (2) using silicon-zirconium or silicon-hafnium binary alloy powder to perform an embedding reaction infiltration on the porous low-density C / C substrate under vacuum, and performing surface treatment on the obtained material to obtain an ultrahigh-temperature ceramic matrix composite material comprising an integrated coating; wherein the ultrahigh-temperature ceramic matrix composite material comprises a gradually decreasing content of ZrC or HfC ultrahigh-temperature ceramic phase and a gradually increasing content of SiC ceramic phase from the outer surface to the interior direction; (3) using a CVI-SiC process to modify the integrated coating on the surface of the composite material to obtain the lightweight ablation-resistant ultrahigh-temperature ceramic matrix composite material.

2. The production method according to claim 1, characterized by, In step (1), the carbon fiber preform is any one of a carbon fiber needle structure, a carbon cloth laminated stitched structure or a fine woven puncture structure; and / or The carbon fiber prepreg has a density of 0.50 to 0.80 g / cm 3 .

3. The preparation method according to claim 1, characterized in that, In step (1), a pyrolytic carbon interface layer is deposited on the surface of the carbon fibers in the carbon fiber preform by chemical vapor deposition; wherein, during the vapor deposition process, the carbon source used is propylene, the carrier gas is nitrogen, the deposition temperature is 800-1100℃, and the density increment of the carbon fiber preform after deposition of the pyrolytic carbon is 0.30-0.50 g / cm 3 . Before depositing the pyrolytic carbon interface layer on the surface of the carbon fiber in the carbon fiber preform, a step of performing high-temperature preheating treatment on the carbon fiber preform is further included; preferably, the temperature of the high-temperature preheating treatment is 1500-2000℃, and the holding time is 2.0-3.0h.

4. The method of claim 1, wherein, In step (1), the impregnation is performed by vacuum pressure impregnation; wherein the vacuum degree is 5-100Pa, the pressure is 0.5-2.0MPa, the temperature is room temperature, and the time is 0.5-2.0h; The curing temperature is 100-300℃, the pressure is 0.5-2.5MPa, and the time is 0.5-2.0h; The pyrolysis temperature is 700-1000℃, and the time is 2.0-4.0h; and / or After impregnation, curing and pyrolysis, the density increment of the carbon fiber preform on which the pyrolytic carbon interface layer is deposited is 0.30-0.50 g / cm 3 .

5. The preparation method according to claim 1, characterized in that, In step (2), the atomic fraction of zirconium in the silicon-zirconium binary alloy powder is 18-23 at.%, and the atomic fraction of hafnium in the silicon-hafnium binary alloy powder is 19-28 at.%; More preferably, the particle size of the silicon-zirconium or silicon-hafnium binary alloy powder is 1-10μm.

6. The method of claim 1, wherein, In step (2), the reaction infiltration is performed under vacuum at a temperature of 1600-1800℃ and a holding time of 1.0-2.0h.

7. The preparation method according to claim 1, characterized in that, In step (2), the surface treatment is grinding or cutting treatment; Preferably, after the surface treatment, the thickness of the integrated coating obtained is 100-200μm.

8. The method of claim 1, wherein, In step (3), when the CVI-SiC process is used for modification, the raw material is methyltrichlorosilane, the hydrogen flow rate is 0.25-0.60 m 3 / h, the argon flow rate is 0.40-1.00 m 3 / h, the deposition temperature is 950-1150℃, and the deposition time is 10-30 h.

9. The production method according to claim 8, characterized by, In step (3), the thickness of the SiC coating formed after the modification is 10-30μm.

10. A lightweight ablation-resistant ultrahigh-temperature ceramic matrix composite material prepared by the preparation method of any one of claims 1-9.

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