MAX phase-carbide phase composite interface layer modified carbon fiber and preparation method thereof

Abstract

The invention discloses an MAX phase-carbide phase composite interface layer modified carbon fiber and a preparation method thereof, and belongs to the technical field of ceramic-based composite materials and functional coatings, an MAX phase ceramic layer is rapidly constructed on the surface of the carbon fiber through a process of combining precursor solution dipping with transient carbon thermal shock, and the MAX phase-carbide phase composite interface layer modified carbon fiber is obtained. Meanwhile, carbide ceramic can be introduced below the MAX phase to serve as an auxiliary transition layer, the MAX phase is selected from Cr2GaC, Cr2AlC, Zr2AlC, Mn2GaC and Zr3InC2, due to the unique layered structure and high-temperature stability of the MAX phase, the bonding strength and toughness of a carbon fiber interface can be remarkably improved, the thermal mismatch problem of the interface is solved, the material is endowed with excellent conductivity and electrochemical activity, and the material can be used for preparing a high-performance carbon fiber material. The material shows stable performance under high-temperature oxidation, reduction and inert atmospheres, and can be widely applied to high-temperature-resistant composite materials, electrodes and chemical catalyst carriers.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composite materials and functional coating technology, specifically to a MAX phase interface composite interface layer modified carbon fiber and its preparation method, as well as the application of this material in high-temperature resistant composite materials and catalyst supports. Background Technology

[0002] Ceramic-reinforced carbon fiber matrix composites, with their excellent high-temperature stability, oxidation resistance, and good mechanical properties, have shown great application potential in aerospace thermal protection systems, key components of gas turbines, and high-temperature chemical equipment. As an important direction for advanced structural and functional integrated materials, the overall performance of these composites largely depends on the interface control between the ceramic reinforcing phase and the carbon fiber matrix. Due to the significant differences between ceramics and carbon fibers in their coefficients of thermal expansion, chemical activity, and mechanical properties, problems such as unstable interfacial bonding, microcrack initiation, and insufficient stress transfer efficiency often arise, thus limiting the reliability and service life of the materials in extreme environments. Therefore, how to achieve precise design and effective control of the interface structure has become a key scientific and engineering challenge to promote the further development of ceramic-reinforced carbon fiber matrix composites.

[0003] Traditional interface modification techniques primarily rely on constructing an interface layer on the carbon fiber surface to optimize interface properties. Currently widely used interface layer materials, such as pyrolytic carbon (PyC) and boron nitride (BN), while improving interfacial bonding to some extent, suffer from severe instability in high-temperature oxidizing environments, making them highly susceptible to oxidation failure. This leads to interface layer peeling and a sharp decline in composite material properties. Particularly in high-temperature oxidizing environments above 500°C, these traditional interface materials cannot provide long-term stable interface protection, becoming a key bottleneck restricting the high-temperature applications of carbon fiber matrix composites.

[0004] In recent years, MAX phase ceramics have been considered important candidates to replace traditional interface materials due to their unique layered structure, excellent thermal conductivity, good high-temperature toughness, and radiation resistance. MAX phase materials (such as Cr2GaC, Cr2AlC, Zr2AlC, Mn2GaC, and Zr3InC2) combine the high-temperature stability of ceramics with the electrical and thermal conductivity of metals, exhibiting excellent structural stability in high-temperature oxidizing environments. Meanwhile, transition metal carbides (such as VC, Cr3C2, ZrC, NbC, MoC, HfC, TaC, and WC) exhibit outstanding high-temperature structural stability, excellent electrical conductivity, and good thermodynamic compatibility with carbon materials, making them an important component in constructing high-performance interface ceramic coatings.

[0005] However, existing technologies still face numerous challenges in preparing such high-performance ceramic interface layers on carbon fiber surfaces. While traditional methods such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) can produce high-quality ceramic coatings, they are complex, require expensive equipment, consume high energy, and struggle to achieve uniform coating of the fiber surface. More critically, the controllable preparation of MAX phase-carbide ceramic composite interface layers on carbon fiber surfaces, especially the rapid generation of high-quality, firmly bonded composite interface layers without compromising the original mechanical properties of the fibers, remains a major technical challenge for current research.

[0006] Therefore, the electric heating industry needs to develop a simple, efficient, and cost-controllable preparation process to accurately construct the MAX phase-carbide phase composite interface layer on the carbon fiber surface, in order to meet the urgent demand for high-performance carbon fiber materials in high-end application fields such as high-temperature composite materials and electrocatalytic materials. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an interface-modified carbon fiber with a MAX phase as its core and its preparation method. The MAX phase layer is rapidly constructed on the carbon fiber surface through a transient carbon thermal shock process, and a carbide layer can be selectively introduced as a transition or reinforcing interface. This effectively solves the key problems of performance degradation and insufficient interfacial bonding of traditional carbon fibers under high-temperature oxidation environments, and provides important technical support for high-end applications of carbon fibers in aerospace thermal protection, new energy electrodes, catalyst carriers and other fields.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A MAX-carbide phase composite interface layer modified carbon fiber includes a carbon fiber matrix and a composite interface layer coated on the surface of the carbon fiber matrix. The composite interface layer is composed of a carbide ceramic layer and a MAX phase ceramic layer. The carbide ceramic layer is selected from one of VC, Cr3C2, ZrC, NbC, MoC, HfC, TaC, and WC, and the MAX phase ceramic layer is selected from one of Cr2GaC, Cr2AlC, Zr2AlC, Mn2GaC, and Zr3InC2.

[0009] Preferably, the MAX phase ceramic layer is Cr2GaC.

[0010] Preferably, the carbon fiber has a diameter of 1~20μm.

[0011] Preferably, the morphology of the composite interface layer is one of nanoparticle, thin film, needle-like, or network structure.

[0012] This invention also claims a method for preparing the MAX phase-carbide phase composite interface layer modified carbon fiber, comprising the following steps: (1) Carbon fiber pre-surface treatment: The carbon fiber matrix is ​​subjected to high-temperature pulse pretreatment in an inert atmosphere; Preferably, in step (1), high-temperature pulse treatment is performed 1 to 5 times to remove surface oil and impurities; the inert atmosphere is argon or nitrogen atmosphere, and the process parameters of high-temperature pulse are: voltage 20 to 60V, current 2 to 5A, heating temperature 800 to 1200℃, and heating time 0.2 to 1s.

[0013] (2) Carbide precursor loading and construction: The metal salt ethanol solution was used as the carbide precursor solution and dropped onto the surface of the pretreated carbon fiber matrix. The carbon fiber matrix was dried to form a carbide precursor loading layer. The carbon fiber matrix loaded with the precursor was subjected to transient carbon thermal shock treatment by electric current in an inert atmosphere to construct a carbide ceramic interface layer on its surface in situ. Preferably, in step (2), the metal salt is one or more of the chloride and nitrate salts of V, Cr, Zr, Nb, Mo, Hf, Ta, and W, and the concentration of the carbide precursor solution is 0.02~0.5 mol / L.

[0014] Preferably, in step (2), the method of adding the carbide precursor solution is as follows: the carbon fiber is placed on a constant temperature heating platform of 80~140℃, and the precursor solution is added dropwise in a volume of 5~100μL each time. After the solvent evaporates, the next drop is added until the precursor solution is completely added to the surface of the carbon fiber; the loaded metal in the carbide precursor loading layer accounts for 1~50wt% of the carbon fiber matrix.

[0015] Specifically, in step (2), the carbide precursor solution can be added dropwise in amounts of 5 μL, 10 μL, 20 μL, 50 μL, and 100 μL each time.

[0016] Preferably, in step (2), the process parameters for transient carbon thermal shock are: applied voltage 20~60V, current 3~12A, transient heating temperature 1000~2000℃, holding time 0.2~1s, and heating rate 1000~10000K / s.

[0017] (3) Loading and construction of MAX phase precursor: An ethanol solution of MAX phase metal salt and carbon source is used as the MAX phase precursor solution and dropped onto the surface of carbon fiber with a carbide layer. The carbon fiber is dried to form a MAX phase precursor loading layer. The carbon fiber loaded with MAX phase precursor is subjected to carbothermal shock treatment in an inert atmosphere. The MAX phase ceramic layer is constructed in situ on the surface of the carbide ceramic interface layer, and finally the MAX phase-carbide phase composite interface layer modified carbon fiber is obtained.

[0018] Preferably, in step (3), the metal salt of the M layer in the MAX phase precursor solution is one of Cr(NO3)3, Zr(NO3)4, and Mn(NO3)2, the metal salt of the A layer is one of Ga(NO3)3, Al(NO3)3, and In(NO3)3, and the carbon source is one of anhydrous citric acid, polyacrylonitrile, sucrose, glucose, and carbon black; preferably, the molar ratio of different elements in the MAX phase is M layer metal: A layer metal: carbon source = 2:1:9 or 3:1:9.

[0019] Preferably, in step (3), the method of adding the MAX phase precursor solution is as follows: the carbon fiber is placed on a constant temperature heating table at 80~140℃, and the precursor solution is added dropwise in a volume of 5~100μL each time. After the solvent evaporates, the next drop is added until the precursor solution is completely added to the surface of the carbon fiber. The loaded metal in the MAX phase precursor loading layer accounts for 1~50wt% of the carbon fiber matrix.

[0020] Specifically, in step (3), the MAX phase precursor solution can be added dropwise in amounts of 5 μL, 10 μL, 20 μL, 50 μL, and 100 μL each time.

[0021] Preferably, in step (3), the process parameters for transient carbon thermal shock are: applied voltage 20~60V, current 2~10A, transient heating temperature 600~1400℃, holding time 1~600s, and heating rate 1000~10000K / s.

[0022] This invention also claims the application of the MAX phase-carbide phase composite interface layer modified carbon fiber in high-temperature resistant composite materials and high-temperature electrocatalytic support materials.

[0023] Compared with the prior art, the present invention has the following beneficial effects: 1. The system is universal and the process is simple. This invention is compatible with carbides such as VC, Cr3C2, ZrC, NbC, MoC, HfC, TaC, and WC, as well as MAX phases such as Cr2GaC, Cr2AlC, Zr2AlC, Mn2GaC, and Zr3InC2, to construct a multi-component composite interface layer; it adopts a one-step in-situ synthesis method of precursor solution impregnation-transient carbothermal shock, with a heating rate of 10³~10 4 With a heat preservation time of ≤600s, it eliminates the need for traditional multi-step and long-term processes, has a simple route, adjustable parameters, and can quickly respond to the different requirements of interface components in different application scenarios.

[0024] 2. Controllable coating morphology and strong interfacial adhesion. This invention achieves composite interfacial layers with various controllable morphologies, such as nanoparticles, thin films, needles, and networks, by precisely controlling the precursor concentration, dropping process, and heat treatment parameters. The MAX phase and carbide ceramics possess excellent electrical conductivity, chemical stability, and thermal stability, enabling optimization of interfacial thermal stability while maintaining the original mechanical properties of carbon fibers. The constructed interfacial layer bonds firmly to the carbon fiber matrix, effectively enhancing the bonding strength between the carbon fiber and ceramic interface, and solving the key problems of strong surface inertia and insufficient interfacial adhesion in traditional carbon fibers.

[0025] 3. Dual oxidation resistance and improved service temperature of the coating. The MAX phase layered structure and high interfacial compatibility can release thermal stress, while the carbide layer provides a dense oxygen diffusion barrier. Together, they form a dual "sealing-healing" mechanism. This composite interface design enables the modified carbon fiber to work stably for a long time in high-temperature oxidizing environments above 500℃, effectively preventing the oxidation and ablation of carbon fiber, making it particularly suitable for high-temperature thermal protection scenarios.

[0026] 4. Modulated electrical conductivity, suitable for high-temperature electrocatalysis. Typically, both MAX phases and carbide ceramics possess a wide range of electrical conductivity, and the composite interface layer allows for flexible control of the overall electrical properties of the carbon fiber. This characteristic enables the modified carbon fiber to exhibit higher stability in high-temperature oxidizing atmosphere thermocatalysis and high-temperature electrocatalytic reactions, showing broad application prospects in electrothermal chemical production, fuel cells, water electrolysis for hydrogen production, and high-temperature electrolysis. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below.

[0028] Figure 1 The images show the XRD pattern and microstructure of the Cr2GaC-MoC phase composite interface layer modified carbon fiber of Example 1 of this invention. Figure 2 The images show the XRD pattern and microstructure of the Cr2GaC-TaC phase composite interface layer modified carbon fiber in Example 2 of this invention. Figure 3 The XRD pattern and microstructure of the Cr2GaC-WC phase composite interface layer modified carbon fiber in Example 3 of this invention are shown. Figure 4 Images of modified carbon fiber and pure carbon fiber felt in air burning according to Example 2 of the present invention; Figure 5 The graph shows the temperature change over time of pure carbon fiber, Example 1, Comparative Example 1, and Comparative Example 2 samples when Joule heating is applied in air. Figure 6Thermogravimetric analysis curves of samples from Example 1, Comparative Example 1, and Comparative Example 2 are shown. Figure 7 The graph shows the thermal stability of Joule heating under different chemical atmospheres in Example 1. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0030] A method for preparing carbon fibers modified with a MAX phase-carbide phase composite interface layer includes the following steps: (1) Place the carbon fiber matrix in an inert atmosphere and perform high-temperature pulse pretreatment 1 to 5 times to remove surface oil and impurities. The process parameters of high-temperature pulse are: voltage 20 to 60V, current 2 to 5A, heating temperature 800 to 1200℃, and heating time 0.2 to 1s. (2) Prepare an ethanol solution of one or more of the chloride and nitrate salts of V, Cr, Zr, Nb, Mo, Hf, Ta, and W to obtain a 0.02~0.5 mol / L carbide precursor solution; (3) Place the carbon fiber on a constant temperature heating table at 80~140℃, and add the carbide precursor solution dropwise in amounts of 5~100μL each time. Wait for the solvent to evaporate completely before adding the next drop, until the precursor solution is completely dripped onto the surface of the carbon fiber. Dry to form a carbide precursor supported layer; the loaded metal in the carbide precursor supported layer accounts for 1~50wt% of the carbon fiber matrix. (4) Apply current to the carbon fiber matrix loaded with carbide precursor in an inert atmosphere to perform transient carbon thermal shock treatment. The applied voltage is 20~60V, the current is 3~12A, the transient heating temperature is 1000~2000℃, the holding time is 0.2~1s, and the heating rate is 1000~10000K / s. A carbide ceramic interface layer is constructed in situ on the surface of the carbon fiber matrix. (5) Prepare an ethanol solution of the M layer metal salt (one of Cr(NO3)3, Zr(NO3)4, Mn(NO3)2), the A layer metal salt (one of Ga(NO3)3, Al(NO3)3, In(NO3)3) and the carbon source (one of anhydrous citric acid, polyacrylonitrile, sucrose, glucose, carbon black) to obtain the MAX phase precursor solution. The molar ratio of the M layer metal salt, the A layer metal salt and the carbon source is 2:1:9 or 3:1:9.

[0031] (6) Place the carbon fiber on a constant temperature heating platform at 80~140℃, and add the MAX phase precursor solution dropwise in amounts of 5~100μL each time. Wait for the solvent to evaporate completely before adding the next drop, until the precursor solution is completely dropped onto the surface of the carbon fiber. Dry to form a MAX phase precursor supported layer; the loaded metal in the MAX phase precursor supported layer accounts for 1~50wt% of the carbon fiber matrix. (7) The carbon fiber matrix loaded with MAX phase precursor was subjected to carbon thermal shock treatment in an inert atmosphere. The voltage was 20~60V, the current was 2~10A, the transient heating temperature was 600~1400℃, the holding time was 1~600s, and the heating rate was 1000~10000K / s. The MAX phase ceramic layer was constructed in situ on the surface of the carbide ceramic interface layer to obtain MAX phase-carbide phase composite interface layer modified carbon fiber.

[0032] The present invention will be further described below through specific embodiments.

[0033] Example 1 A method for preparing Cr2GaC-MoC phase composite interface layer modified carbon fiber includes the following steps: (1) The carbon fiber matrix (0.5×3cm carbon felt) was placed in an inert atmosphere and subjected to high temperature pulse pretreatment twice to remove surface oil and impurities. The process parameters of high temperature pulse were: voltage 60V, current 3A, heating temperature 1000℃, and heating time 0.2s. (2) MoCl5 was prepared into an ethanol solution to obtain a 0.2 mol / L carbide precursor solution; carbon fiber was placed on a constant temperature heating platform at 120℃, and the carbide precursor solution was added dropwise in 20 μL increments. After the solvent evaporated, the next addition was made until the precursor solution was completely added to the carbon fiber surface. The carbon fiber was dried to form a carbide precursor loading layer; the loaded metal in the carbide precursor loading layer accounted for 20 wt% of the carbon fiber matrix; the carbon fiber matrix loaded with carbide precursor was subjected to transient carbon thermal shock treatment by applying current in an inert atmosphere. The applied voltage was 60 V, the current was 8 A, the transient heating temperature was 1800℃, the holding time was 0.6 s, and the heating rate was 5000 K / s. A carbide ceramic interface layer was constructed in situ on the surface of the carbon fiber matrix. (3) Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid were prepared into an ethanol solution to obtain a MAX phase precursor solution. The molar ratio of Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid in the MAX phase precursor solution was 2:1:9. The carbon fiber was placed on a constant temperature heating platform at 120℃. The MAX phase precursor solution was added dropwise in 20μL increments. After the solvent evaporated, the next addition was made until the precursor solution was completely added to the surface of the carbon fiber. The carbon fiber was dried to form a MAX phase precursor loading layer. The loaded metal in the MAX phase precursor loading layer accounted for 20wt% of the carbon fiber matrix. The carbon fiber matrix loaded with the MAX phase precursor was subjected to carbothermal shock treatment in an inert atmosphere. The voltage was 60V, the current was 3A, the transient heating temperature was 1000℃, the holding time was 60s, and the heating rate was 5000K / s. The MAX phase ceramic layer was constructed in situ on the surface of the carbide ceramic interface layer to obtain Cr2GaC-MoC phase composite interface layer modified carbon fiber.

[0034] The X-ray diffraction (XRD) and scanning electron microscope (SEM) images of the composite material are as follows: Figure 1 As shown.

[0035] Example 2 A method for preparing Cr2GaC-TaC phase composite interface layer modified carbon fiber includes the following steps: (1) The carbon fiber matrix (0.5×3cm carbon felt) was placed in an inert atmosphere and subjected to high temperature pulse pretreatment twice to remove surface oil and impurities. The process parameters of high temperature pulse were: voltage 60V, current 4A, heating temperature 1200℃, and heating time 0.2s. (2) Prepare an ethanol solution of TaCl5 to obtain a 0.2 mol / L carbide precursor solution; place the carbon fiber on a constant temperature heating platform at 120℃, and add the carbide precursor solution dropwise in 20 μL increments. Wait for the solvent to evaporate and then add the next increment until the precursor solution is completely added to the carbon fiber surface. Dry the carbon fiber to form a carbide precursor loading layer; the loaded metal in the carbide precursor loading layer accounts for 50 wt% of the carbon fiber matrix; apply current to the carbon fiber matrix loaded with carbide precursor in an inert atmosphere to perform transient carbon thermal shock treatment. Apply voltage 60 V, current 10 A, transient heating temperature 2000℃, holding time 0.2 s, heating rate 5000 K / s, and construct a carbide ceramic interface layer in situ on the surface of the carbon fiber matrix. (3) Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid were prepared into an ethanol solution to obtain a MAX phase precursor solution. The molar ratio of Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid in the MAX phase precursor solution was 2:1:9. The carbon fiber was placed on a constant temperature heating platform at 120℃. The MAX phase precursor solution was added dropwise in 20μL increments. After the solvent evaporated, the next addition was made until the precursor solution was completely added to the surface of the carbon fiber. The carbon fiber was dried to form a MAX phase precursor loading layer. The loaded metal in the MAX phase precursor loading layer accounted for 50wt% of the carbon fiber matrix. The carbon fiber matrix loaded with the MAX phase precursor was subjected to carbothermal shock treatment in an inert atmosphere. The voltage was 60V, the current was 5A, the transient heating temperature was 1400℃, the holding time was 30s, and the heating rate was 5000K / s. The MAX phase ceramic layer was constructed in situ on the surface of the carbide ceramic interface layer to obtain the MAX phase-carbide phase composite interface layer modified carbon fiber.

[0036] The XRD and SEM images of the composite material are as follows: Figure 2 As shown.

[0037] Example 3 A method for preparing Cr2GaC-WC phase composite interface layer modified carbon fiber includes the following steps: (1) The carbon fiber matrix (0.5×3cm carbon felt) was placed in an inert atmosphere and subjected to high temperature pulse pretreatment twice to remove surface oil and impurities. The process parameters of high temperature pulse were: voltage 40V, current 2A, heating temperature 800℃, and heating time 1s. (2) WCl5 was prepared into an ethanol solution to obtain a 0.2 mol / L carbide precursor solution; carbon fiber was placed on a constant temperature heating platform at 120℃, and the carbide precursor solution was added dropwise in 20 μL increments. After the solvent evaporated, the next addition was made until the precursor solution was completely added to the carbon fiber surface. The carbon fiber was dried to form a carbide precursor loading layer; the loaded metal in the carbide precursor loading layer accounted for 5 wt% of the carbon fiber matrix; the carbon fiber matrix loaded with the carbide precursor was subjected to transient carbon thermal shock treatment by applying current in an inert atmosphere. The applied voltage was 60 V, the current was 10 A, the transient heating temperature was 2000℃, the holding time was 0.2 s, and the heating rate was 5000 K / s. A carbide ceramic interface layer was constructed in situ on the surface of the carbon fiber matrix. (3) Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid were prepared into an ethanol solution to obtain a MAX phase precursor solution. The molar ratio of Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid in the MAX phase precursor solution was 2:1:9. The carbon fiber was placed on a constant temperature heating platform at 120℃. The MAX phase precursor solution was added dropwise in 20μL increments. After the solvent evaporated, the next addition was made until the precursor solution was completely added to the surface of the carbon fiber. The carbon fiber was dried to form a MAX phase precursor loading layer. The loaded metal in the MAX phase precursor loading layer accounted for 5wt% of the carbon fiber matrix. The carbon fiber matrix loaded with the MAX phase precursor was subjected to carbothermal shock treatment in an inert atmosphere. The voltage was 40V, the current was 2A, the transient heating temperature was 800℃, the holding time was 600s, and the heating rate was 5000K / s. The MAX phase ceramic layer was constructed in situ on the surface of the carbide ceramic interface layer to obtain Cr2GaC-TaC phase composite interface layer modified carbon fiber.

[0038] The XRD and SEM images of the composite material are as follows: Figure 3 As shown.

[0039] Comparative Example 1 A method for preparing carbide interface layer modified carbon fiber includes the following steps: (1) The carbon fiber matrix (0.5×3cm carbon felt) was placed in an inert atmosphere and subjected to high temperature pulse pretreatment twice to remove surface oil and impurities. The process parameters of high temperature pulse were: voltage 60V, current 3A, heating temperature 1000℃, and heating time 0.2s. (2) MoCl5 was prepared into an ethanol solution to obtain a 0.2 mol / L carbide precursor solution; carbon fiber was placed on a constant temperature heating platform at 120℃, and the carbide precursor solution was added dropwise in 20 μL increments. After the solvent evaporated, the next addition was made until the precursor solution was completely added to the carbon fiber surface. The carbon fiber was dried to form a carbide precursor loading layer; the loaded metal in the carbide precursor loading layer accounted for 20 wt% of the carbon fiber matrix; the carbon fiber matrix loaded with the carbide precursor was subjected to transient carbon thermal shock treatment by applying current in an inert atmosphere. The applied voltage was 60 V, the current was 8 A, the transient heating temperature was 1800℃, the holding time was 0.6 s, and the heating rate was 5000 K / s. A carbide ceramic interface layer was constructed in situ on the surface of the carbon fiber matrix.

[0040] Comparative Example 2 A method for preparing MAX phase composite interface layer modified carbon fiber includes the following steps: (1) The carbon fiber matrix (0.5×3cm carbon felt) was placed in an inert atmosphere and subjected to high temperature pulse pretreatment twice to remove surface oil and impurities. The process parameters of high temperature pulse were: voltage 60V, current 3A, heating temperature 1000℃, and heating time 0.2s. (2) Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid were prepared into an ethanol solution to obtain a MAX phase precursor solution. The molar ratio of Cr(NO3)3, Ga(NO3)3 and anhydrous citric acid in the MAX phase precursor solution was 2:1:9. The carbon fiber was placed on a constant temperature heating platform at 120℃. The MAX phase precursor solution was added dropwise in 20μL increments. After the solvent evaporated, the next addition was made until the precursor solution was completely added to the surface of the carbon fiber. The carbon fiber was dried to form a MAX phase precursor loading layer. The loaded metal in the MAX phase precursor loading layer accounted for 20wt% of the carbon fiber matrix. The carbon fiber matrix loaded with the MAX phase precursor was subjected to carbothermal shock treatment in an inert atmosphere. The voltage was 60V, the current was 3A, the transient heating temperature was 1000℃, the holding time was 60s, and the heating rate was 5000K / s. The MAX phase ceramic layer was constructed in situ on the surface of the carbide ceramic interface layer to obtain the MAX phase interface layer modified carbon fiber.

[0041] Relevant performance tests: (1) Air combustion test: The sample from Example 1 and the untreated carbon felt were burned in air at a flame of about 900°C. The results showed that, compared with carbon fiber, the modified carbon fiber composite material provided by the present invention exhibited significantly improved high-temperature oxidation resistance. The composite material maintained good integrity after burning for 30 seconds, while the pure carbon fiber felt showed obvious defects (e.g., Figure 4 (As shown).

[0042] (2) Joule heat resistance test: Pure carbon fiber, samples from Comparative Example 1 and Comparative Example 2, and samples from Example 1 were subjected to a suitable current in air, instantly heating their temperature to approximately 525°C. After holding this temperature for 600 seconds, the pure carbon felt and Comparative Example 1 oxidized and broke in air. The Cr2GaC@CFs sample from Comparative Example 2 remained intact, but its temperature fluctuated slightly. The Cr2GaC / MoC@CFs sample from Example 1 exhibited very small temperature fluctuations and remained intact after Joule heating in air for 600 seconds. The surface composite coating significantly enhanced the high-temperature oxidation resistance of the carbon fiber matrix (e.g., ...). Figure 5 (As shown).

[0043] (3) Thermal analysis test: Figure 6 Thermogravimetric analysis (TGA) graphs of the composite materials in Example 1 and Comparative Examples 1 and 2 in air atmosphere are shown. The thermogravimetric results show that the composite material in Example 1 has better thermal stability compared with the composite materials in Comparative Examples 1 and 2. The mass of the material decreases by only 3.2% at 600°C, which proves the strong thermal stability of the composite material at a high temperature of 600°C.

[0044] (4) Testing of chemical catalyst support: Figure 7The results of thermal stability tests of the sample from Example 1 as a Joule-heated catalyst support under different chemical reaction atmospheres (Ar / H2 atmosphere, CO2 atmosphere, and H2 / CO2 = 3:1 mixed atmosphere) are shown. The results indicate that the modified carbon fiber can maintain structural integrity and excellent thermal stability in both oxidizing and reducing environments, further verifying its application potential and reliable performance as a high-temperature chemical catalyst support.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A MAX phase-carbide phase composite interface layer modified carbon fiber, characterized in that, The invention includes a carbon fiber matrix and a composite interface layer coated on the surface of the carbon fiber matrix. The composite interface layer is composed of a carbide ceramic layer and a MAX phase ceramic layer. The carbide ceramic layer is selected from one of VC, Cr3C2, ZrC, NbC, MoC, HfC, TaC, and WC, and the MAX phase ceramic layer is selected from one of Cr2GaC, Cr2AlC, Zr2AlC, Mn2GaC, and Zr3InC2.

2. The carbon fiber modified with a MAX phase-carbide phase composite interface layer according to claim 1, characterized in that, The carbon fiber has a diameter of 1~20μm.

3. A method for preparing carbon fibers modified with a MAX phase-carbide phase composite interface layer as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Carbon fiber pre-surface treatment: The carbon fiber matrix is ​​subjected to high-temperature pulse pretreatment in an inert atmosphere; (2) Construction of carbide interface layer: The metal salt ethanol solution is used as the carbide precursor solution and is dropped onto the surface of the pretreated carbon fiber matrix. The carbon fiber matrix loaded with the carbide precursor is dried to form a carbide precursor loading layer. The carbon fiber matrix loaded with the carbide precursor is subjected to transient carbon thermal shock treatment by electric current in an inert atmosphere to construct a carbide ceramic interface layer in situ on its surface. (3) Construction of MAX phase-carbide composite interface layer: The ethanol solution of MAX phase metal salt and carbon source is used as MAX phase precursor solution and dropped onto the surface of carbon fiber that has formed carbide ceramic interface layer. The carbon fiber is dried to form MAX phase precursor loading layer. The carbon fiber loaded with MAX phase precursor is subjected to carbothermal shock treatment in an inert atmosphere. The MAX phase ceramic layer is constructed in situ on the surface of carbide ceramic interface layer, and finally MAX phase-carbide phase composite interface layer modified carbon fiber is obtained.

4. The preparation method according to claim 3, characterized in that, In step (1), high-temperature pulse treatment is performed 1 to 5 times to remove surface oil and impurities; the inert atmosphere is argon or nitrogen atmosphere, and the process parameters of high-temperature pulse are: voltage 20 to 60V, current 2 to 5A, heating temperature 800 to 1200℃, and heating time 0.2 to 1s.

5. The preparation method according to claim 3, characterized in that, In step (2), the metal salt is one or more of the chloride and nitrate salts of V, Cr, Zr, Nb, Mo, Hf, Ta, and W, and the concentration of the carbide precursor solution is 0.02~0.5 mol / L.

6. The preparation method according to claim 3, characterized in that, In step (2), the loaded metal in the carbide precursor loading layer accounts for 1 to 50 wt% of the carbon fiber matrix.

7. The preparation method according to claim 3, characterized in that, In step (2), the process parameters for transient carbon thermal shock are: applied voltage 20~60V, current 3~12A, transient heating temperature 1000~2000℃, holding time 0.1~1s, and heating rate 1000~10000K / s.

8. The preparation method according to claim 3, characterized in that, In step (3), the metal salt of the M layer in the MAX phase precursor solution is one of Cr(NO3)3, Zr(NO3)4, and Mn(NO3)2, the metal salt of the A layer is one of Ga(NO3)3, Al(NO3)3, and In(NO3)3, and the carbon source is one of anhydrous citric acid, polyacrylonitrile, sucrose, glucose, and carbon black; wherein the molar ratio of different elements in the MAX phase is M layer metal: A layer metal: carbon source = 2:1:9 or 3:1:

9.

9. The preparation method according to claim 3, characterized in that, In step (3), the loaded metal in the MAX phase precursor loading layer accounts for 1~50wt% of the carbon fiber matrix.

10. The preparation method according to claim 3, characterized in that, In step (3), the process parameters for transient carbon thermal shock are: applied voltage 20~60V, current 2~10A, transient heating temperature 600~1400℃, holding time 1~600s, and heating rate 1000~10000K / s.

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