A multi-component carbon fiber reinforced composite material and a low-temperature infiltration preparation method

Abstract

The application discloses a multi-component carbon fiber reinforced composite material and a low-temperature infiltration preparation method. The reaction infiltration technology is adopted, a low-melting-point infiltrant is used as a carrier, a high-melting-point component is introduced into the C / C composite material at low temperature, different components are enriched in different regions according to the reaction rate difference of each component and pyrolytic carbon, the internal content of the low-melting-point phase is reduced, and the ablation resistance is improved.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber reinforced composite materials technology, and relates to a multi-component carbon fiber reinforced composite material and a low-temperature melt infiltration preparation method. Background Technology

[0002] Carbon / carbon (C / C) composites have attracted considerable interest in the aerospace field due to their lightweight, moderate coefficient of thermal expansion (CTE), and excellent mechanical properties. However, rapid damage caused by oxidation sensitivity (rapid oxidation above 111°C) remains a key challenge limiting their widespread application. Current research on oxidation / ablation protection of carbon fiber reinforced composites mainly focuses on coating and matrix modification technologies. Coating technology typically involves depositing or coating the surface of C / C composites with single or multiple layers of substances containing one or more antioxidant / ablation-resistant components, isolating the internal composite material from direct contact with oxygen, thus achieving effective protection. This approach offers advantages such as ease of operation and high design flexibility. Reference 1, “Guanghui Feng, Hejun Li, Xiyuan Yao, et al. Evaluation of ablation-resistant ZrC-SiC multilayer coating for SiC coated carbon / carbon composites under oxyacetylene and laser conditions[J]. Corrosion Science, 2122, 215, 111127,” employs supersonic plasma spraying technology to spray coatings with different ZrC to SiC ratios onto the surface of C / C composites with embedded SiC inner coatings. This achieves an adjustable design for multilayer coatings, which can provide better high-temperature protection because they not only integrate the advantages of different sublayers but also have better toughness than single-layer coatings. However, under high-temperature and high-pressure airflow conditions, the coating has a different coefficient of thermal expansion (CTE) than the C / C composite material. Furthermore, the embedded SiC inner coating undergoes active oxidation under high temperature and low oxygen partial pressure conditions. The gas generated by the active oxidation of the SiC inner coating damages the surface oxide film and leaves a porous structure. All of these factors cause the coating to peel off, thereby losing its protective function for the C / C composite material and causing catastrophic damage to the C / C composite material.

[0003] Matrix modification technology holds promise for solving this problem by introducing antioxidant / ablation-resistant components into C / C composites with low density (1.1 g / cm³–1.1 g / cm³) and high porosity (31–51%), thereby improving the overall antioxidant / ablation resistance of the material. Matrix modification technologies mainly include precursor impregnation pyrolysis (PIP) and reactive infiltration (RMI) techniques. PIP (Polymer Injection Process) uses a polymer containing ultra-high temperature ceramics as a precursor. The C / C composite material is immersed in the precursor, and through multiple drying, curing, and high-temperature pyrolysis cycles, the ultra-high temperature ceramics are introduced into the C / C composite material. Although PIP introduces a uniform ceramic phase with deep penetration, allowing for compositional design, the precursor is expensive, the ceramic phase yield is only about 31%, the preparation cycle is long, multiple high-temperature heat treatments cause significant damage to the carbon fibers, and the prepared composite material has a large porosity, often requiring additional processes for densification, making industrial application difficult. RMI (Regenerative Thermal Injection) involves heating the substance or its compound to be introduced to a temperature above its melting point, allowing it to flow into the C / C composite material. Through in-situ reaction with the pyrolytic carbon inside the C / C composite material, ultra-high temperature ceramics are generated. It has advantages such as near-net-shape molding, low production cost, short preparation cycle, and high density. Reference 2, “RunningWang, Ni Li, Jiaping Zhang, et al. Ablation behavior of sharp leading-edge C / C-ZrC-SiC composites using 3111℃ oxyacetylene torch[J]. Corrosion Science, 2122, 216, 111551,” proposes introducing ablation-resistant components ZrC and SiC into sharp leading-edge components through reactive infiltration. These components oxidize to form ZrO2 and SiO2. ZrO2 has a high melting point (2711℃) and covers the surface of the C / C composite during ablation, but it is difficult to sinter densely, often requiring the introduction of low-melting-point self-healing components to promote sintering. SiO2 has a lower melting point (1721℃) and forms a flowing liquid SiO2 glass phase during ablation, healing cracks and pores on the surface. It works synergistically with ZrO2 to form a dense Zr-Si-O oxide film on the surface of the C / C composite, preventing oxygen from entering the matrix and protecting the material. However, during the melting process, due to the high reaction temperature (1911~2111℃) of the selected melt ZrSi2, the carbon fibers react with the melt, damaging the integrity of the carbon fibers and greatly reducing the mechanical properties of the components. At the same time, under the conditions of high temperature and low oxygen partial pressure, SiC inside the matrix undergoes active oxidation to generate SiO, which is released from the matrix and damages the surface oxide film. Furthermore, the melting process is difficult to control and cannot achieve precise structural design like coatings.

[0004] To address the issue of high-temperature reaction between melt and carbon fiber damaging mechanical properties, researchers have conducted a series of studies on low-temperature melt infiltration. Reference 3, "Yuanqi Weng, Xin Yang, Feixiong Chen, et al. Structure evolution and ablative mechanism of C / C-ZrC-ZrxCuy composites with lowporosity fabricated by pressure assisted reactive melt infiltration[J]. Corrosion Science, 2122, 219, 111811," utilizes reactive melt infiltration technology, using Zr-Cu alloy as the infiltrator, to prepare C / C-ZrC-Zr composites. x Cu y Composite materials. In the initial stage of ablation, the endothermic effect of the Cu phase effectively reduces the rise in surface temperature. As the ablation time increases, Cu evaporates rapidly, leaving numerous micropores on the oxide film surface. During cooling, ZrO2 gradually transforms from a cubic phase to a tetragonal and then a monoclinic phase, causing volume changes and surface cracks. Due to the lack of low-melting-point self-healing components, the micropores and cracks are difficult to heal, becoming oxygen diffusion channels and ultimately leading to material failure. Therefore, low-melting-point self-healing components such as SiO2, TiO2, and Ta2O5 need to be introduced into the material to fill cracks and pores. Simultaneously, they can undergo solid solution reaction with ZrO2, inhibiting the phase transformation of ZrO2 and mitigating the evaporation of low-melting-point phases such as SiO2, TiO2, and Ta2O5.

[0005] In summary, achieving compositional and structural design and control within C / C composites through matrix modification technology remains a key focus and challenge in current research. Furthermore, from an engineering and industrial application perspective, considering cost and time constraints, RMI (Reinforcing Membrane Infiltration) is a viable option. However, conventional Zr-Si and Hf-Si systems suffer from high melting temperatures, severely damaging mechanical properties; their single composition fails to achieve the synergistic effect of multiple components to improve ablation performance; and the negative impact of SiC formed within the matrix on the oxide film under high-temperature conditions are all problems that urgently need to be addressed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-component carbon fiber reinforced composite material and a low-temperature melt infiltration preparation method to solve the problems in the existing reactive melt infiltration technology, such as severe damage to carbon fibers by the melt, resulting in a decrease in mechanical properties, and insufficient depth of melt penetration into the C / C matrix, making it difficult to achieve composition and structural design.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A method for preparing multi-component carbon fiber reinforced composite materials by low-temperature melt infiltration includes the following steps:

[0009] Step 1: Place the C / C composite material in a mixed powder, which coats the C / C composite material. The mixed powder consists of a low-melting-point infiltrator and a high-melting-point infiltrator. The low-melting-point infiltrator is Zr-Cu alloy powder, and the high-melting-point infiltrator has a melting point greater than its melting temperature. The high-melting-point infiltrator includes a first-class high-melting-point component and a second-class high-melting-point component. The reaction rate of the first-class high-melting-point component with pyrolytic carbon is lower than that of the low-melting-point infiltrator with pyrolytic carbon, and the reaction rate of the second-class high-melting-point component with pyrolytic carbon is lower than that of the first-class high-melting-point component with pyrolytic carbon.

[0010] Step 2: Vacuum negative pressure reaction melting infiltration is carried out at 1211~1111℃ to obtain multi-component carbon fiber reinforced composite material.

[0011] A further improvement of the present invention is that:

[0012] Preferably, the Zr content in the Zr-Cu alloy powder is 51–75 wt.%.

[0013] Preferably, the first type of high-melting-point component is Ti, and the second type of high-melting-point component is Si.

[0014] Preferably, by mass fraction, the mixed powder contains 61-91 wt.% Zr-Cu alloy powder, 5-31 wt.% Ti powder, and 5-21 wt.% Si powder.

[0015] Preferably, before step 1, the C / C composite material is processed into a regular shape.

[0016] Preferably, before step 1, the preparation process of the mixed powder is as follows: ball milling and mixing the low melting point infiltrator and the high melting point infiltrator, then sieving and drying to obtain the powder.

[0017] Preferably, in step 1, the process of wrapping the C / C composite material with the mixed powder is as follows: covering the bottom and sides of the graphite crucible with graphite paper, laying the mixed powder on the graphite paper, placing the C / C composite material on the laid mixed powder, and adding more mixed powder to wrap the C / C composite material.

[0018] Preferably, in step 2, the vacuum negative pressure is 1.1 × 11 -2 MPa.

[0019] Preferably, in step 2, the heating parameters for the reaction melting and infiltration are: heating to 1211-1111℃ at a heating rate of 5-11℃ / min, holding at that temperature for 1.5-3 hours, and then cooling to 811℃ at a cooling rate of 5-11℃ / min.

[0020] A carbon fiber reinforced composite material prepared by any one of the above preparation methods includes a C / C composite material and ZrC. ZrC is uniformly distributed inside the C / C composite material. The surface layer of the C / C composite material is enriched with the reaction products of two types of high melting point components and pyrolytic carbon. The middle layer of the C / C composite material is enriched with the reaction products of one type of high melting point component and pyrolytic carbon. The inner layer is a multiphase mixed region.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention discloses a low-temperature melt infiltration method for preparing multi-component carbon fiber reinforced composite materials. This method utilizes low-temperature negative pressure reactive melt infiltration technology to introduce a high-melting-point infiltrator and Zr-Cu alloy powder into the interior of the carbon fiber reinforced carbon matrix composite material, where they react with pyrolytic carbon to form a ceramic phase. The low-melting-point Zr-Cu alloy is used as a fluid to introduce the unmelted high-melting-point infiltrator into the C / C matrix, allowing for its introduction at a relatively low infiltration temperature. During infiltration, the high-melting-point infiltrator reacts with the C / C matrix through a solid-solid reaction. The lower infiltration temperature avoids damage to the fiber's mechanical properties caused by high temperatures. By leveraging the difference in reaction rates between Zr, the first-order high-melting-point component, the second-order high-melting-point component, and pyrolytic carbon, the reaction products of the second-order high-melting-point component and pyrolytic carbon are characterized by a lower content in the inner layer and a higher content in the outer layer. Simultaneously, the reaction products of the first-order high-melting-point component and pyrolytic carbon are present in the composite material, preparing a multi-component reinforced composite material without damaging the C / C matrix. This method combines the excellent oxidation / ablation resistance of ultra-high temperature ceramics with the low density and excellent high-temperature mechanical strength of C / C composite materials. The selected raw materials are inexpensive, and the preparation method has a short cycle time, showing good industrial application prospects and economic benefits. This invention employs reactive melting infiltration technology, using a low-melting-point infiltration agent as a carrier to introduce high-melting-point components into the C / C composite material at low temperatures. Based on the different reaction rates of each component with pyrolytic carbon, different components accumulate in different regions, reducing the content of the low-melting-point phase and improving ablation resistance. The method of this invention also has the following advantages:

[0023] (1) In view of the difference in thermal expansion coefficient between the coating and the C / C substrate, the coating is prone to peeling under high temperature and strong airflow. The present invention adopts reactive melting and infiltration technology to modify the C / C substrate and avoid the problem of coating peeling.

[0024] (2) In view of the problem that conventional melting infiltration systems such as Zr-Si and Hf-Si have high melting infiltration temperatures, which cause serious corrosion to carbon fibers and damage to mechanical properties, this invention uses low-melting-point Zr-Cu alloy as a melting infiltrator and carries out reactive melting infiltration at a low temperature of 1211~1111℃ to protect mechanical properties.

[0025] (3) In view of the problem that conventional melting and infiltration systems have a single component and cannot achieve multi-component synergistic modification of C / C, this invention uses Zr-Cu alloy as melting and infiltration agent and liquid Zr and Cu as fluids to introduce substances with melting points higher than melting and infiltration temperature into the interior of C / C in the form of solid particles, thus solving the problem of introducing multiple components through traditional combination of multiple processes.

[0026] (1) In view of the problem of high surface temperature during the ablation process, the present invention uses Zr-Cu alloy as a melting agent. Cu plays a role in sweating and cooling during the ablation process, reducing the ablation surface temperature by 211 to 311℃.

[0027] Furthermore, one type of high-melting-point component is Ti, and the other type is Si. Ti-modified Zr-Cu alloy powder and Si powder are introduced into the interior of carbon fiber reinforced carbon matrix composites, reacting with pyrolytic carbon to form a ceramic phase. This invention uses low-melting-point Zr-Cu alloy powder as a fluxing agent, utilizing liquid Zr and Cu as fluids to introduce unmelted Ti and Si into the matrix, lowering the fluxing temperature and avoiding damage to the fiber's mechanical properties. Ti-modified Zr-Cu alloy powder can improve the wettability of Cu with C / C, addressing the problem of insufficient fluxing depth. Simultaneously, Ti reacts with pyrolytic carbon to generate TiC, which helps improve ablation resistance. Utilizing the difference in reaction rates between Zr, Ti, Si, and pyrolytic carbon, a characteristic of lower SiC content in the inner layer and higher content in the outer layer is achieved, mitigating the damage to the surface oxide film caused by the active oxidation of internal SiC during ablation.

[0028] Furthermore, addressing the issue of insufficient melt penetration depth during the melting process, this invention first employs negative pressure melting, utilizing the pressure difference to allow the melt to penetrate into the C / C matrix; secondly, by adding Ti powder to the Zr-Cu melting agent, the wettability of Cu on the C / C matrix is ​​improved, enabling the melt to better penetrate the matrix. A density of 1.2 g / cm³ is selected. 3 A C / C composite with an open porosity of 11.1% underwent reactive melting and infiltration. Under normal pressure, the melt could not penetrate the C / C interior because Cu and C / C are non-wetting. Under negative pressure without the addition of Ti, the density after melting and infiltration reached 2.92 g / cm³. 3 The open porosity is 19.13%, indicating high porosity; after adding Ti under negative pressure, the density reaches 3.33 g / cm³. 3 With an open porosity of 7.7%, the melting and infiltration effect is significantly improved by 81.95% compared to the effect without Ti powder under normal pressure.

[0029] Furthermore, addressing the challenge of achieving structural control through matrix modification techniques, this invention leverages the different reaction rates of Zr, Ti, and Si with C. Zr exhibits strong reactivity with C and reacts first, resulting in a uniform distribution of ZrC within the material. Ti reacts with C at a secondary rate, while Si reacts with C at the slowest rate. Si flows into the C / C matrix along with the liquid Zr and Cu fluids. However, unable to react with the pyrolytic carbon in time, Si flows out of the C / C matrix with the melt, ultimately forming a SiC-rich layer on the surface of the C / C composite material. By utilizing this characteristic, a multiphase mixed region is prepared with uniformly distributed ZrC, a SiC-rich surface layer, a TiC-rich middle layer, and carbon fiber as the reinforcing phase in the inner layer, with ZrC as the dominant phase. This solves the problem of achieving structural design through matrix modification techniques.

[0030] Furthermore, in conventional Zr-Si and Hf-Si systems with high internal SiC content, active oxidation of internal SiC occurs under high temperature and low oxygen partial pressure conditions, generating SiO gas and damaging the integrity of the surface oxide film. This invention utilizes the slow reaction rate of Si and C, resulting in a lower internal SiC content, thus reducing the damage to the surface oxide film caused by active oxidation of internal SiC under high temperature and low oxygen partial pressure conditions. Attached Figure Description

[0031] Figure 1 These are scanning electron microscope images of the melt infiltration depth of the multi-component carbon fiber reinforced composite material prepared by low-temperature melt infiltration in Example 1;

[0032] Figure 2 These are scanning electron microscope and energy dispersive spectroscopy images of the multi-component carbon fiber reinforced composite material prepared by low-temperature melt infiltration in Example 1;

[0033] Figure 3 These are X-ray diffraction patterns of the surface and cross-section of the composite material prepared in Example 1;

[0034] Figure 4 This is a curve showing the change in contact angle of Cu / C / C composite material with Ti content at high temperature;

[0035] Figure 5 It refers to the reaction rates of the three elements Zr, Ti, and Si with C;

[0036] Figure 6 This is the damage to carbon fiber caused by the high-temperature melt in Comparative Example 1;

[0037] Figure 7 This is a schematic diagram of the final multi-component composite material. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0039] The first aspect of this invention discloses a method for preparing multi-component carbon fiber reinforced composite materials by low-temperature melt infiltration. This method employs reactive melt infiltration technology, using a low-melting-point melt infiltrator as a carrier to introduce high-melting-point components into the C / C composite material at low temperature. Based on the difference in reaction rates between each component and pyrolytic carbon, different components exhibit enrichment characteristics in different regions, thereby reducing the content of the low-melting-point phase and improving ablation performance.

[0040] The specific steps are as follows:

[0041] Step 1: Coat the C / C composite material with the mixed powder. The mixed powder consists of a low-melting-point infiltrator and a high-melting-point infiltrator. The low-melting-point infiltrator is Zr-Cu alloy powder, and the melting point of the high-melting-point infiltrator is greater than the melting temperature.

[0042] Step 2: Vacuum negative pressure reaction melting infiltration is carried out at 1211~1111℃ to obtain multi-component carbon fiber reinforced composite material.

[0043] This process utilizes the fact that Zr-Cu alloy powder is completely liquid between 1211 and 1111℃, allowing it to carry a high-melting-point infiltrator into the C / C composite material during the melting and infiltration process. Simultaneously, the infiltrator reacts with the C / C composite material. This low-temperature, negative-pressure reaction melting and infiltration process avoids damage to the fiber's mechanical properties due to the low temperature, while the negative pressure improves the problem of insufficient melting and infiltration depth.

[0044] In some embodiments of the present invention, the low-melting-point infiltrator is a Zr-Cu alloy powder containing 51–75 wt.% Zr. Verification has shown that Zr-Cu alloy powder within this composition range exhibits good flow properties, enabling it to penetrate into the interior of the C / C composite material. Furthermore, this content of Zr-Cu alloy powder, after reaction, produces a suitable amount of ZrC and Cu. ZrC enhances high-temperature ablation resistance, while Cu acts as a cooling agent during ablation, reducing the material surface temperature and improving high-temperature service performance.

[0045] In some embodiments of the present invention, the C / C composite material in step 1 has a regular shape, such as a cube, sphere, or ellipsoid, so that the mixed powder can be uniformly infiltrated during the melting and infiltration process.

[0046] In some embodiments of the present invention, the preparation process of the mixed powder is as follows: ball milling and mixing a low-melting-point infiltrator and a high-melting-point infiltrator, then sieving and drying to obtain the powder. This results in a uniform mixed powder with a particle size that meets the infiltration requirements.

[0047] In some embodiments of the present invention, in step 1, the process of wrapping the C / C composite material with the mixed powder is as follows: covering the bottom and sides of the graphite crucible with graphite paper, laying the mixed powder on the graphite paper, placing the C / C composite material on the laid mixed powder, and adding more mixed powder to wrap the C / C composite material.

[0048] In some embodiments of the present invention, the high-melting-point infiltrator is divided into a first-class high-melting-point component and a second-class high-melting-point component. The reaction rates of the components in the mixed powder with pyrolytic carbon differ, causing different components to accumulate in different regions due to these rate differences. Specifically, the reaction rate of the first-class high-melting-point component with pyrolytic carbon is lower than that of the low-melting-point infiltrator with pyrolytic carbon, and the reaction rate of the second-class high-melting-point component with pyrolytic carbon is lower than that of the first-class high-melting-point component with pyrolytic carbon; that is, ranked by reaction rate with pyrolytic carbon, the reaction rate of the low-melting-point infiltrator > the first-class high-melting-point component > the second-class high-melting-point component.

[0049] Specifically, the preferred high-melting-point component of this invention is Ti, and the preferred high-melting-point component is Si. In actual application, different elements can be replaced according to the melting point of the component, as long as the above rules are met.

[0050] In some embodiments of the present invention, the mixed powder comprises a Zr-Cu alloy containing 51-75% zirconium by mass, Ti powder, and Si powder, with the following proportions: 61-91 wt.% Zr-Cu, 5-31 wt.% Ti, and 5-21 wt.% Si. The addition of Ti powder to the mixed powder improves both the ablation resistance and the wettability of Cu to C / C.

[0051] In some embodiments of the present invention, the packaged crucible is placed in a vacuum autoclave, with a vacuum degree ≤1.1×11 throughout the process. -2 The temperature was increased to 1211-1111℃ at a heating rate of 5-11℃ / min, held for 1.5-3 hours, and then cooled to 811℃ at a cooling rate of 5-11℃ / min. After that, the power was turned off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material.

[0052] Another aspect of the present invention discloses a multi-component carbon fiber reinforced composite material, which is a C / C composite material. The interior of the C / C composite material is uniformly distributed with ZrC. The outer surface layer of the material is uniformly enriched with the reaction products of two types of high melting point components and pyrolytic carbon. The middle layer of the material is enriched with the reaction products of one type of high melting point component and pyrolytic carbon. The inner layer is a multiphase mixed region with ZrC as the main component and TiC and SiC as the smaller components.

[0053] See Figure 7Because Zr reacts fastest with pyrolytic carbon, as the Zr-Cu cryogenic infiltrator penetrates inward, Zr simultaneously reacts with the pyrolytic carbon in the C / C composite to form ZrC. A type of high-melting-point component with a moderate reaction rate typically penetrates into the material as solid particles with the cryogenic infiltrator and begins to react with the pyrolytic carbon, forming a reaction product of high-melting-point component and pyrolytic carbon, which forms the intermediate layer. The second type of high-melting-point component, with the slowest reaction rate, infiltrates into the C / C composite as solid particles with the cryogenic infiltrator, but due to its slow reaction rate with pyrolytic carbon, it does not have time to react and flows out of the C / C composite, reacting with the pyrolytic carbon on the surface, forming the surface layer. The inner layer of the C / C composite is a multiphase mixed region dominated by ZrC, where all the remaining substances react with the C / C composite, forming the multiphase region. It should be noted that... Figure 7 This is just a structural diagram, reflecting the relative positions of the surface layer, intermediate layer, and multiphase region. In reality, the boundaries and shapes of the three regions may not be so uniform.

[0054] Specifically, when Ti is one type of high-melting-point component and Si is another type of high-melting-point component, the main material of the composite material is a C / C composite material, in which ZrC is uniformly distributed, SiC is enriched in the surface layer, TiC is enriched in the middle layer, and the inner layer is a multiphase mixed region.

[0055] Example 1

[0056] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0057] (2) A Zr-Cu alloy powder containing 71% zirconium by mass was ball-milled with Ti powder and Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder composition was as follows: 85 wt.% Zr-Cu, 11 wt.% Ti, and 5 wt.% Si;

[0058] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0059] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2The temperature was increased to 1211℃ at a rate of 11℃ / min, held for 2 hours, and then cooled to 811℃ at a rate of 5℃ / min. After that, the power was turned off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material.

[0060] Example 2

[0061] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0062] (2) A Zr-Cu alloy powder containing 71% zirconium by mass was ball-milled with Ti powder and Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder composition was as follows: 65 wt.% Zr-Cu, 31 wt.% Ti, and 5 wt.% Si;

[0063] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0064] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2 The temperature was increased to 1311℃ at a rate of 11℃ / min, held for 2 hours, and then cooled to 811℃ at a rate of 5℃ / min. After that, the power was turned off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material.

[0065] Example 3

[0066] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0067] (2) A Zr-Cu alloy powder containing 71% zirconium by mass was ball-milled with Ti powder and Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder composition was as follows: 85 wt.% Zr-Cu, 11 wt.% Ti, and 5 wt.% Si;

[0068] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0069] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2 The temperature was increased to 1111℃ at a rate of 11℃ / min, held for 2 hours, and then cooled to 811℃ at a rate of 5℃ / min. After that, the power was turned off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material.

[0070] Comparative Example 1:

[0071] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0072] (2) A Zr-Cu alloy powder containing 71% zirconium by mass was ball-milled with Ti powder and Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder composition was as follows: 85 wt.% Zr-Cu, 11 wt.% Ti, and 5 wt.% Si;

[0073] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0074] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2 The temperature was increased to 1911℃ at a rate of 11℃ / min, held for 2 hours, and then cooled to 811℃ at a rate of 5℃ / min. After that, the power was cut off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material. Due to the high melting and infiltration temperature, the carbon fibers were severely eroded by the melt, leaving a large number of bundle-like pores inside the material.

[0075] Comparative Example 2:

[0076] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0077] (2) The Zr-Cu alloy powder containing 71% zirconium by mass was ball-milled with Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder ratio is as follows: 85 wt.% Zr-Cu, 15 wt.% Si;

[0078] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0079] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2 The temperature was increased to 1311℃ at a rate of 11℃ / min, held for 2 hours, and then decreased to 811℃ at a rate of 5℃ / min. The furnace was then cooled with the power off, yielding a multi-component carbon fiber reinforced composite material. However, the melt penetration depth was insufficient, resulting in two large un-melted areas in the cross-section of the material. The density after melt penetration reached 2.92 g / cm³. 3 It has an open porosity of 19.13% and a relatively high porosity.

[0080] Figure 1 This is a scanning electron microscope (SEM) image of the melting depth of the multi-component carbon fiber reinforced composite material prepared by low-temperature melting infiltration in Example 1. The white areas represent the ceramic phases ZrC, TiC, SiC, and Cu, while the black areas represent carbon fiber bundles. The image shows that the white ceramic phases have penetrated into the interior of the C / C composite material. Before melting infiltration, the density of the C / C composite material was 1.2 g / cm³. 3 The porosity is 11.1%; the density of the composite material obtained after melt infiltration is 3.33 g / cm³. 3 The porosity was 7.7%, indicating that the method has good sealing and melting effects.

[0081] Figure 2 These are scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) images of the multi-component carbon fiber reinforced composite material prepared by low-temperature melt infiltration in Example 1. Based on the different colors in the EDS images, obvious regional enrichment phenomena can be observed, which can be divided into regions I, II, and III, corresponding to the surface layer, intermediate layer, and inner layer, respectively. From the EDS images of C, Zr, Ti, and Si, it can be seen that ZrC is uniformly distributed, SiC is enriched in the surface layer, TiC is enriched in the intermediate layer, and the inner layer is a multi-phase mixed region with carbon fiber as the reinforcing phase and ZrC as the main phase.

[0082] Figure 3 These are X-ray diffraction patterns of the surface and cross-section of the composite material prepared in Example 1. The surface XRD pattern shows that the surface is mainly composed of TiC and SiC, with a low ZrC content. The cross-sectional XRD pattern shows that the interior is mainly composed of ZrC, with extremely low SiC and TiC contents. This confirms that the carbon fiber reinforced composite material prepared by this method has a low SiC content and also proves that Ti and Si elements are effectively introduced into the C / C matrix. No elemental Zr, Ti, or Si appears in either XRD pattern, indicating that the infiltrator has completely reacted with the pyrolytic carbon layer without any residue. This also confirms... Figure 1 The substances appearing in the energy spectrum are ZrC, TiC, and SiC.

[0083] Figure 4 The curve shows the change of the contact angle of Cu to C / C composite material with Ti content at high temperature. It indicates that as the Ti content increases, the contact angle of Cu to C / C matrix gradually decreases, eventually reaching 1°, and the contact angle changes from non-wetting to complete wetting.

[0084] Figure 5 The reaction rates of Zr, Ti, and Si with C are given by the Gibbs free energy (ΔG), which represents the extent of the reaction. Lower energy indicates a more readily occurring reaction. At a melting temperature of 1111℃, the Gibbs free energy of SiC differs from that of TiC and ZrC by 81 kJ / mol and 111 kJ / mol, respectively. This indicates that the reaction of Zr with C to form ZrC occurs first, followed by TiC, and finally SiC. This also confirms that Si, as it enters the C / C mixture with the melt, cannot react in time and flows out of the C / C mixture with the melt, thus accumulating in surface region I to form a SiC-rich layer.

[0085] Figure 6 This is the damage to carbon fibers caused by the high-temperature melt in Comparative Example 1. Due to the high melting and infiltration temperature (1911℃) selected, the carbon fibers inside the material have been reacted by the high-temperature melt, leaving bundle-like pores.

[0086] Example 4

[0087] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0088] (2) A Zr-Cu alloy powder containing 51% zirconium by mass was ball-milled with Ti powder and Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder composition was as follows: 61 wt.% Zr-Cu, 31 wt.% Ti, and 11 wt.% Si;

[0089] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0090] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2The temperature was increased to 1211℃ at a rate of 5℃ / min, held for 3 hours, and then cooled to 811℃ at a rate of 11℃ / min. After that, the power was turned off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material.

[0091] Example 5

[0092] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0093] (2) A Zr-Cu alloy powder containing 61% zirconium by mass was ball-milled with Ti powder and Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder composition was as follows: 91 wt.% Zr-Cu, 5 wt.% Ti, and 5 wt.% Si;

[0094] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0095] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2 The temperature was increased to 1311℃ at a rate of 8℃ / min, held for 1 hour, and then cooled to 811℃ at a rate of 8℃ / min. After that, the power was turned off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material.

[0096] Example 6

[0097] (1) The density is 1.2 g / cm³ 3 The low-density C / C composite material with an open porosity of 11.1% was processed into a cube of 11×11×11mm, ultrasonically cleaned with deionized water for 2 hours, and then placed in an 81℃ oven to dry for 21 hours for later use.

[0098] (2) A Zr-Cu alloy powder containing 55% zirconium by mass was ball-milled with Ti powder and Si powder for 6 hours, sieved through a 211-mesh sieve, and dried in an oven at 81°C for 21 hours for later use. The mixed powder composition was as follows: 75 wt.% Zr-Cu, 5 wt.% Ti, and 21 wt.% Si;

[0099] (3) Wrap graphite paper around the bottom and sides of the graphite crucible, spread a thin layer of mixed powder on the graphite paper at the bottom of the graphite crucible, place the C / C composite material on the powder, and add mixed powder until the C / C composite material is evenly covered by the mixed powder.

[0100] (1) Place the packaged crucible in a vacuum autoclave and evacuate it to a vacuum level of 1.1 × 11⁻¹ throughout the process. -2 The temperature was increased to 1111℃ at a rate of 9℃ / min, held for 1.5h, and then cooled to 811℃ at a rate of 11℃ / min. After that, the power was turned off and the furnace was cooled to obtain a multi-component carbon fiber reinforced composite material.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing multi-component carbon fiber reinforced composite materials by low-temperature melt infiltration, characterized in that, Includes the following steps: Step 1: Place the C / C composite material in a mixed powder, which coats the C / C composite material. The mixed powder consists of a low-melting-point infiltrator and a high-melting-point infiltrator. The low-melting-point infiltrator is Zr-Cu alloy powder, and the high-melting-point infiltrator has a melting point higher than its melting temperature. The high-melting-point infiltrator includes a first-class high-melting-point component and a second-class high-melting-point component. The reaction rate of the first-class high-melting-point component with pyrolytic carbon is lower than that of the low-melting-point infiltrator with pyrolytic carbon, and the reaction rate of the second-class high-melting-point component with pyrolytic carbon is lower than that of the first-class high-melting-point component with pyrolytic carbon. The first-class high-melting-point component is Ti, and the second-class high-melting-point component is Si. Step 2: Vacuum negative pressure reaction melting infiltration is carried out at 1200 ~ 1400 ℃ to obtain multi-component carbon fiber reinforced composite material; In the multi-component carbon fiber reinforced composite material, ZrC is uniformly distributed, SiC is enriched in the surface layer, TiC is enriched in the middle layer, and the inner layer is a multiphase mixed region. The multiphase mixed region uses carbon fiber as the reinforcing phase and ZrC as the main phase.

2. The method for preparing a multi-component carbon fiber reinforced composite material by low-temperature melt infiltration according to claim 1, characterized in that, The Zr content in the Zr-Cu alloy powder is 50 ~ 75 wt.%.

3. The method for preparing a multi-component carbon fiber reinforced composite material by low-temperature melt infiltration according to claim 1, characterized in that, The mixed powder contains 60-90 wt.% Zr-Cu alloy powder, 5-30 wt.% Ti powder, and 5-20 wt.% Si powder by mass fraction.

4. The method for preparing a multi-component carbon fiber reinforced composite material by low-temperature melt infiltration according to claim 1, characterized in that, Before step 1, the C / C composite material is processed into a regular shape.

5. The method for preparing a multi-component carbon fiber reinforced composite material by low-temperature melt infiltration according to claim 1, characterized in that, Before step 1, the preparation process of the mixed powder is as follows: ball milling and mixing of low melting point infiltrator and high melting point infiltrator, sieving, and drying to obtain the powder.

6. The method for preparing a multi-component carbon fiber reinforced composite material by low-temperature melt infiltration according to claim 1, characterized in that, In step 1, the process of wrapping the C / C composite material with the mixed powder is as follows: cover the bottom and sides of the graphite crucible with graphite paper, lay the mixed powder on the graphite paper, place the C / C composite material on the laid mixed powder, and add more mixed powder to wrap the C / C composite material.

7. The method for preparing a multi-component carbon fiber reinforced composite material by low-temperature melt infiltration according to claim 1, characterized in that, In step 2, the vacuum negative pressure is 1.0 × 10⁻⁶. -2 MPa.

8. The method for preparing a multi-component carbon fiber reinforced composite material by low-temperature melt infiltration according to claim 1, characterized in that, In step 2, the heating parameters for the reaction melting and infiltration are as follows: the temperature is raised to 1200-1400℃ at a heating rate of 5-10℃ / min, held for 0.5-3 hours, and then cooled to 800℃ at a cooling rate of 5-10℃ / min.

9. A carbon fiber reinforced composite material prepared by the preparation method according to any one of claims 1-8, characterized in that, The composite material includes C / C composites and ZrC. ZrC is uniformly distributed inside the C / C composite. The surface layer of the C / C composite is enriched with SiC, a reaction product of two types of high-melting-point components, Si and pyrolytic carbon. The middle layer of the C / C composite is enriched with TiC, a reaction product of one type of high-melting-point component, Ti and pyrolytic carbon. The inner layer is a multiphase mixed region, in which carbon fiber is used as the reinforcing phase and ZrC is the main phase.

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