Carbon-carbon composite material with temperature-resistant sealing performance, preparation method and application thereof

Abstract

The application relates to the technical field of new materials, and discloses a carbon-carbon composite material with temperature-resistant sealing performance and a preparation method and application thereof. The carbon-carbon composite material comprises single carbon fibers and multi-layered graphite sheets surrounding the periphery of the single carbon fibers, and the surface of the single carbon fibers and each graphite sheet is attached with non-carbon element nanoparticles, wherein the non-carbon element nanoparticles contain iron elements, aluminum elements, phosphorus elements, lead elements, cobalt elements, optional IIA group elements and optional indium elements. The carbon-carbon composite material disclosed by the application is composed of layered graphite sheet clusters with a concentric circle structure in a microscale, the interior of the layered graphite sheet clusters contains specific non-carbon element nanoparticles in addition to carbon, the non-carbon element nanoparticles contain specific metal elements and phosphorus elements, and the non-carbon elements are uniformly distributed in the graphite sheet clusters with specific structures in an atomic scale; the carbon-carbon composite material with the characteristics has excellent high-temperature resistance and sealing performance.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, specifically to a carbon-carbon composite material with temperature-resistant sealing properties, its preparation method, and its application. Background Technology

[0002] Carbon fiber possesses a comprehensive set of properties, including high tensile strength, high tensile modulus, low density, high temperature resistance, ablation resistance, corrosion resistance, high electrical and thermal conductivity, low thermal expansion, self-lubrication, and good biocompatibility. It is widely used in aerospace, automotive, building energy, and sporting goods industries. In Chapter 5, "Graphite Fiber," of He Fu's book *Carbon Fiber and Graphite Fiber* (first edition, September 2010), it states that graphite fiber generally refers to carbon fiber with a carbon content of over 99%. Graphite fiber can be obtained by graphitizing carbon fiber at high temperatures of 2200–3000℃. Graphite fiber not only has a high carbon content but also a high tensile modulus. It exhibits excellent properties such as a low coefficient of thermal expansion, good thermal stability, and dimensional stability, making it suitable for manufacturing rigid, thin, and dimensionally stable composite materials, widely used in aerospace applications, particularly in spacecraft. For example, high-modulus carbon fiber composites are used to manufacture the horn antennas of artificial satellites to ensure dimensional stability in the temperature-changing environment of space.

[0003] Carbon-carbon (C / C) composites refer to multiphase structural materials with carbon fibers or their fabrics as the reinforcing phase and pyrolytic carbon through chemical vapor infiltration or resin carbon or pitch carbon impregnated and carbonized through liquid phase as the matrix (domestic patent: CN112125690A). They possess extremely high specific strength and specific modulus, and can be used at temperatures above 2000℃ in an inert atmosphere without degradation of mechanical properties, exhibiting characteristics unmatched by any other material. C / C composites are non-melting and non-flammable, exhibit uniform ablation, and are widely used in the outer wall materials of space shuttles, missile nose cones, and engine nozzles. C / C composites are excellent thermal conductors with a low coefficient of thermal expansion, and are resistant to friction and wear, making them widely used in aircraft braking systems. C / C composites are prepared by densifying preforms made from carbon fiber filaments or short-cut carbon fiber composite matrix carbon through liquid phase impregnation and carbonization or chemical vapor deposition and chemical vapor infiltration.

[0004] The fabrication of carbon-carbon composite materials integrates high-temperature technology and equipment. The key to its continuous graphitization preparation lies in suppressing and controlling the high-temperature oxidation and biochemical (evaporation) of the graphite heating element and the running fibers. Carbon-carbon composite materials exhibit macroscopically diverse morphologies due to their different stacking / arrangement in three-dimensional space. These diverse carbon materials are composed of microcrystals of varying sizes and orientations, and stacking states. Catalytically grown carbon nanofibers exhibit a variety of morphologies; different catalysts and raw materials produce tubular, herringbone-like, and planar carbon nanofibers with different structures.

[0005] CN111807853A discloses a preparation process and application of carbon-carbon composite parts, which uses carbon fiber, vapor-deposited carbon, and impregnated carbon composites to maintain good mechanical, thermal, and tribological properties at high temperatures, reduces costs by 50%, and allows for mass production. CN112125690A uses flake graphite and UV-cured silicone to prepare a mixed colloid, which is then filled between a mixed layer of carbon fiber and glass fiber to prepare an intermediate. The carbon-carbon composite material is prepared by hot-pressing, curing, and drying, and exhibits high tensile strength and high elasticity. CN112679950A discloses a method for preparing flexible carbon-carbon composite materials. After coating the surface of carbon fiber cloth with a thermosetting resin film, hot-pressing and curing are performed, followed by carbonization in an inert atmosphere. This method has the advantages of short processing time, simple process, no need for high-pressure equipment, and high production efficiency, enabling industrial production. CN113175565A discloses a thin-walled, high-strength carbon-carbon composite pipe and its preparation method. The pipe comprises a pipe body formed by carbon cloth, binder, and CVD lamination, and a dense layer located on the inner surface of the pipe body. This pipe has the advantage of reducing wall thickness while maintaining strength. CN113636854A discloses a carbon-carbon composite material with deposited carbon nanotubes. Short-cut carbon fibers are embedded within a carbon matrix and carbon fibers, and carbon nanotubes are deposited between them, significantly improving the mechanical properties and oxidation resistance of the carbon-carbon composite material. CN113636855A discloses an internally antioxidant carbon-carbon composite material, comprising a carbon matrix, carbon fiber reinforcement distributed within the carbon matrix, silicon carbide, zirconium oxide, and alumina, which improves the flame-retardant sealing performance and service life of the composite material. CN113683437A discloses a carbon-carbon composite material containing refractory metals, comprising a carbon matrix, carbon fiber reinforcement distributed within the carbon matrix, zirconium-fullerene composite nanoparticles, and silicon-rich silicon carbide, which has the advantages of improving the flame-retardant sealing performance, service life, and oxidation resistance of the composite material. Patents CN113636855A and CN113683437A prepare ablation-resistant carbon-carbon composite materials through seven different operational steps, making the preparation process relatively cumbersome; the experimental conditions used are harsh, and the process is time-consuming. CN115180969A discloses a high thermal conductivity carbon-carbon composite material and its preparation method. It utilizes electrophoresis to produce graphene / AlN reinforcement on the surface and inside of a carbon fiber needle-punched preform, impregnates it in benzoxazine resin, and after thermosetting and atmospheric pressure carbonization, it exhibits excellent mechanical properties and good thermal conductivity. CN115231941A relates to a carbon-carbon composite material for ultra-high temperature environments and its preparation method, including a carbon matrix, carbon fiber reinforcement, ultra-high temperature ceramics and carbon nanotubes. The prepared carbon-carbon composite material has the advantages of excellent mechanical properties, resistance to high temperature ablation and good thermal conductivity.CN213628313U discloses a carbon-carbon composite material sheet, which has the advantages of being lightweight and high-strength, having high thermal conductivity and low expansion, good friction performance, good thermal shock resistance, and high dimensional stability.

[0006] Existing publicly available patent research indicates that most current research on C / C composite materials focuses on improving and optimizing their preparation processes, addressing key technical challenges related to the functional properties and applications of C / C composites. However, the finished products of C / C composite materials disclosed in the prior art are relatively uniform in form, and the main component is only carbon, resulting in poor temperature resistance and sealing performance. Furthermore, there are no reports on C / C composite materials with high aspect ratios and fiber rod-like morphologies. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of existing carbon-carbon composite materials having a single product form, being composed mainly of carbon, and having poor temperature resistance and sealing performance. This invention provides a carbon-carbon composite material with temperature resistance and sealing performance, its preparation method, and its application. At the microscale, this carbon-carbon composite material is composed of layered graphite flakes with a concentric circle structure. In addition to carbon, it contains specific non-carbon element nanoparticles, and these non-carbon elements are uniformly distributed at the atomic scale. This carbon-carbon composite material exhibits excellent temperature resistance and sealing performance.

[0008] To achieve the above objectives, the present invention provides a carbon-carbon composite material with heat-resistant sealing properties. This carbon-carbon composite material comprises a single carbon fiber and multiple layers of graphite sheets surrounding the single carbon fiber. The surfaces of the single carbon fiber and each layer of graphite sheets are coated with non-carbon nanoparticles.

[0009] The non-carbon nanoparticles contain iron, aluminum, phosphorus, lead, cobalt, optional Group IIA elements, and optional indium.

[0010] Preferably, the carbon-carbon composite material contains 50-90% by weight of carbon, 0.5-10% by weight of iron, 0.5-10% by weight of aluminum, 0.2-5% by weight of phosphorus, 0.2-5% by weight of lead, 0.2-5% by weight of cobalt, 0-1% by weight of Group IIA elements and 0-1% by weight of indium.

[0011] Preferably, the carbon-carbon composite material contains 56-80% by weight of carbon, 5-8% by weight of iron, 4-8% by weight of aluminum, 1-3.5% by weight of phosphorus, 1-3.5% by weight of lead, 0.5-3.5% by weight of cobalt, 0.2-0.8% by weight of Group IIA elements and 0.2-0.8% by weight of indium.

[0012] Preferably, the group IIA element is selected from one or more of calcium, strontium, and barium.

[0013] Preferably, the non-carbon element nanoparticles contain iron, aluminum, phosphorus, lead, cobalt, calcium, and indium.

[0014] Preferably, the number of graphite sheets surrounding the outer periphery of the single carbon fiber is 3-20 layers, more preferably 6-12 layers.

[0015] Preferably, the diameter of the single carbon fiber is 4-8 μm, more preferably 4.5-7.5 μm; and the length is 2-10 mm, more preferably 3-9 mm.

[0016] Preferably, the thickness of the multilayer graphite sheets gradually increases from the inside to the outside.

[0017] Preferably, the ratio of the total thickness of the multilayer graphite sheets to the diameter of the single carbon fiber is 1-100:1.

[0018] Preferably, the carbon-carbon composite material is linear and / or curved.

[0019] Preferably, at least a portion of the surface of the carbon-carbon composite material is bamboo-like and / or raised.

[0020] Preferably, the carbon-carbon composite material has a diameter of 0.05-1 mm, more preferably 0.1-0.3 mm, and a length of 0.1-10 mm, more preferably 1-5 mm.

[0021] Preferably, in the Raman spectrum of the carbon-carbon composite material, the ratio of the peak intensity of the D peak to the peak intensity of the G peak is 0.07-0.3:1.

[0022] Preferably, in the Raman spectrum of the carbon-carbon composite material, the ratio of the peak intensity of the 2D peak to the peak intensity of the G peak is 0.2-0.9:1.

[0023] The second aspect of the present invention provides a method for preparing a carbon-carbon composite material with heat-resistant sealing properties, the method comprising: reacting short-cut carbon fibers, a carbon source, a metal source and a phosphorus source at 1500-3500°C in the presence of an inert atmosphere, wherein the volume flow rate of the inert atmosphere is 20-1800 mL / min.

[0024] The metal source includes an iron source, an aluminum source, a lead source, a cobalt source, an optional group IIA element source, and an optional indium source.

[0025] Preferably, the weight ratio of the metal source, the phosphorus source, the carbon source and the chopped carbon fibers is 20-100:3-20:30-200:1, and more preferably 30-70:5-15:50-150:1;

[0026] The weight ratio of the iron source, the aluminum source, the lead source, the cobalt source, the group IIA element source, and the indium source is 0.8-4:1-4:0.3-1.5:1:0-1:0-0.5.

[0027] Preferably, the group IIA element source is selected from one or more of calcium, strontium, and barium sources.

[0028] Preferably, the metal source contains an iron source, an aluminum source, a lead source, a cobalt source, a calcium source, and an indium source.

[0029] Preferably, the iron source is selected from one or more of FeO, Fe2O3, Fe3O4, Fe(OH)2, Fe(OH)3, FeCl2, FeCl3 and FePO4.

[0030] Preferably, the aluminum source is selected from one or more of Al2O3, AlCl3, Al2(SO4)3, Al(OH)3 and AlPO4.

[0031] Preferably, the lead source is selected from one or more of PbO, Pb3O4, PbO2 and Pb2O3.

[0032] Preferably, the cobalt source is selected from one or more of CoO, Co(OH)2, CoCl2 and CoSO4.

[0033] Preferably, the calcium source is selected from one or more of CaCl2, CaO, Ca(OH)2 and CaF2.

[0034] Preferably, the indium source is selected from one or more of In2O3, In(OH)3 and InCl3.

[0035] Preferably, the phosphorus source is selected from one or more of FePO4, AlPO4, Al(PO3)3 and Ca3(PO4)2.

[0036] Preferably, the carbon source is carbonized resin and / or graphite.

[0037] Preferably, the graphite is amorphous graphite.

[0038] Preferably, the reaction temperature is 1500-3000℃; the reaction time is 12-720 hours, preferably 24-120 hours.

[0039] Preferably, the volumetric flow rate of the inert atmosphere is 50-500 mL / min, and more preferably 100-300 mL / min.

[0040] Preferably, the length of the chopped carbon fiber is 0.1-10 mm, more preferably 1-5 mm; the specification is 12-320 K, more preferably 12-48 K; and the carbon content is 85-95% by weight.

[0041] A third aspect of the present invention provides a carbon-carbon composite material with temperature-resistant sealing properties prepared by the method described above.

[0042] The fourth aspect of the present invention provides an application of the carbon-carbon composite material with temperature-resistant sealing properties described above as a temperature-resistant sealing material.

[0043] The carbon-carbon composite material of this invention is composed of layered graphite flakes with a concentric circle structure at the microscale. In addition to carbon, it contains specific non-carbon element nanoparticles, which simultaneously contain specific metal elements and phosphorus elements. Furthermore, the non-carbon elements are uniformly distributed at the atomic scale within the graphite flakes with the specific structure. This carbon-carbon composite material exhibits excellent high-temperature resistance and sealing performance. Preferably, carbon-carbon composite materials containing iron, aluminum, lead, cobalt, calcium, indium, and phosphorus elements exhibit even better high-temperature resistance and sealing performance.

[0044] The method for preparing carbon-carbon composite materials with high temperature resistance and sealing performance described in this invention is simple to operate. Short-cut carbon fibers, carbon source, metal source and phosphorus source are mixed and reacted directly under specific conditions to obtain carbon-carbon composite materials with excellent high temperature resistance and sealing performance. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the macroscopic morphology of the carbon-carbon composite material in Example 1.

[0046] Figures 2-8 The elemental distributions (elemental energy spectrum diagrams) of Fe, Al, P, Pb, Co, Ca, and In inside the carbon-carbon composite material of Example 1 are shown.

[0047] Figure 9 This is a schematic diagram of the cross-sectional morphology of the carbon-carbon composite material in Example 1.

[0048] Figure 10 This is a schematic diagram of the device for testing sealing performance according to the present invention.

[0049] Explanation of reference numerals in the attached figures

[0050] 1 Fixture; 2 First container; 3 Second container; 4 Gas collection bottle; 5 Pipeline; 6 Gas inlet; 7 Sample piece. Detailed Implementation

[0051] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0052] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0053] The first aspect of the present invention provides a carbon-carbon composite material with temperature-resistant sealing properties, the carbon-carbon composite material comprising a single carbon fiber and multiple layers of graphite sheets surrounding the single carbon fiber, wherein the surfaces of the single carbon fiber and each layer of graphite sheets are coated with non-carbon element nanoparticles.

[0054] The carbon-carbon composite material provided by this invention has a unique microstructure. The center of the carbon-carbon composite material is a single carbon fiber, and the outer periphery of the single carbon fiber is surrounded by multiple concentric graphite sheets. Based on this special morphology, non-carbon element nanoparticles containing specific elements can adhere to the surface of the single carbon fiber and each layer of graphite sheets, so that there are non-carbon element nanoparticles between any two layers of graphite sheets and between the single carbon fiber and the first layer of graphite sheets. This ensures that the non-carbon element nanoparticles are evenly distributed in the carbon-carbon composite material, thereby ensuring that the carbon-carbon composite material has good temperature resistance and sealing performance.

[0055] Specifically, the non-carbon element nanoparticles contain iron, aluminum, phosphorus, lead, cobalt, optional Group IIA elements, and optional indium. These non-carbon element nanoparticles containing these specific elements are attached between any two layers of graphite sheets and between a single carbon fiber and the first layer of graphite sheets. Through the synergistic effect of these specific non-carbon elements, the high-temperature resistance and sealing performance of carbon-carbon composite materials can be improved.

[0056] In this invention, there are no particular limitations on the Group IIA elements. In some preferred embodiments, the Group IIA elements are selected from one or more of calcium, strontium, and barium, with calcium being the preferred element.

[0057] In a preferred embodiment, the non-carbon nanoparticles simultaneously contain iron, aluminum, phosphorus, lead, cobalt, calcium, and indium. Combining these specific non-carbon elements, through synergistic effects, can further improve the high-temperature resistance and sealing performance of the carbon-carbon composite material.

[0058] To ensure that the carbon-carbon composite material has both excellent electrical conductivity, excellent high-temperature resistance, and excellent sealing performance, the content of each element in the carbon-carbon composite material must be appropriate.

[0059] In some embodiments, the carbon-carbon composite material contains 50-90% by weight of carbon, 0.5-10% by weight of iron, 0.5-10% by weight of aluminum, 0.2-5% by weight of phosphorus, 0.2-5% by weight of lead, 0.2-5% by weight of cobalt, 0-1% by weight of Group IIA elements and 0-1% by weight of indium.

[0060] In a preferred embodiment, the carbon-carbon composite material contains 56-80 wt% carbon, 5-8 wt% iron, 4-8 wt% aluminum, 1-3.5 wt% phosphorus, 1-3.5 wt% lead, 0.5-3.5 wt% cobalt, 0.2-0.8 wt% Group IIA elements, and 0.2-0.8 wt% indium. Limiting the content of each element in the carbon-carbon composite material to this range further improves its high-temperature resistance and sealing performance.

[0061] In a preferred embodiment, the number of graphite sheets surrounding the outer periphery of the single carbon fiber is 3-20 layers, more preferably 6-12 layers. A greater number of graphite sheets with a concentric circle structure surrounding the outer periphery of the single carbon fiber allows for a more uniform distribution of non-carbon nanoparticles among the graphite sheets, thereby improving the high-temperature resistance and sealing performance of the carbon-carbon composite material.

[0062] In this invention, the diameter of the single carbon fiber can be a conventional choice in the art. In some embodiments, the diameter of the single carbon fiber can be 4-8 μm, preferably 4.5-7.5 μm.

[0063] The length of the single carbon fiber is equivalent to the length of the carbon-carbon composite material; in some preferred embodiments, the length of the single carbon fiber can be 2-10 mm, preferably 3-9 mm.

[0064] The carbon-carbon composite material described in this invention has a unique microstructure. As can be seen from a scanning electron microscope, in a preferred embodiment, the thickness of the multilayer graphite sheets gradually increases from the inside to the outside, which can improve the stability of the concentric circle structure of the carbon-carbon composite material, thereby improving the high temperature resistance and sealing performance of the carbon-carbon composite material.

[0065] The approximate volume ratio of carbon fibers and graphite sheets in a carbon-carbon composite material can be inferred from the ratio of the total thickness of the graphite sheets to the diameter of a single carbon fiber. In a preferred embodiment, the ratio of the total thickness of the multilayer graphite sheets to the diameter of the single carbon fiber can be 1-100:1. Limiting the ratio of the total thickness of the graphite sheets to the diameter of the single carbon fiber within this range can improve the dimensional stability of the concentric structure of the carbon-carbon composite material, maintain the uniform dispersion and firm bonding between the layered graphite sheet clusters, carbon fibers, and non-carbon nanoparticles, thereby improving the high-temperature resistance and sealing performance of the carbon-carbon composite material.

[0066] In this invention, the appearance of the carbon-carbon composite material is not limited and can take on various forms. Specifically, the carbon-carbon composite material is generally straight and / or curved.

[0067] The carbon-carbon composite material provided by this invention further contains carbon particles that exist independently or in an aggregated state, wherein the presence of carbon particles can be observed on the surface of the carbon-carbon composite material. Preferably, the particle size of the carbon particles is 0.02-2 mm.

[0068] In this invention, due to the presence of non-carbon element nanoparticles, the diameter of the carbon-carbon composite material is not uniform. Specifically, at least a portion of the surface of the carbon-carbon composite material has a bamboo-like and / or protruding shape.

[0069] In a specific embodiment, the diameter of the carbon-carbon composite material can be 0.05-1 mm, preferably 0.1-0.3 mm; the length can be 0.1-10 mm, preferably 1-5 mm.

[0070] In this invention, specifically, based on Raman spectroscopy characterization, the ratio of the D peak intensity to the G peak intensity of the carbon-carbon composite material can be 0.07-0.3:1. When the ratio of the D peak intensity to the G peak intensity is within this range, the carbon atom lattice defects are relatively small, and the graphitization degree of the carbon-carbon composite material is relatively complete.

[0071] In this invention, specifically, in the Raman spectrum of the carbon-carbon composite material, the ratio of the peak intensity of the 2D peak to the G peak can be 0.2-0.9:1. When the ratio of the peak intensity of the 2D peak to the G peak is within this range, the carbon atoms have fewer lattice defects, the layered graphite flakes have a perfect and regular graphite structure, and the resulting carbon-carbon composite material has both high-temperature resistance and sealing performance.

[0072] Furthermore, the carbon-carbon composite material described in this invention is gray or black.

[0073] The carbon-carbon composite material of the present invention also contains small amounts of other non-carbon elements, including zinc, manganese, silver, barium, copper, lithium, magnesium, lead and strontium, with the total content of each metal element being less than 0.001 by weight.

[0074] In addition to the aforementioned elements, the carbon-carbon composite material of the present invention also contains oxygen, nitrogen, sulfur and other elements. The metal elements in the carbon-carbon composite material may exist in the form of compounds, and the phosphorus element may exist in the form of phosphate ions.

[0075] A second aspect of this invention provides a method for preparing a carbon-carbon composite material with heat-resistant sealing properties. The method includes: reacting short-cut carbon fibers, a carbon source, a metal source, and a phosphorus source at 1500-3500°C in the presence of an inert atmosphere, wherein the volumetric flow rate of the inert atmosphere is 20-1800 mL / min.

[0076] The metal source includes an iron source, an aluminum source, a lead source, a cobalt source, an optional group IIA element source, and an optional indium source.

[0077] The method described in this invention is simple and easy to operate. It only requires reacting short-cut carbon fibers, a carbon source, a specific metal source, and a phosphorus source under specific conditions.

[0078] In the method described in this invention, if the reaction temperature is too low, concentric graphite sheets cannot be formed on the outside of the carbon fiber, resulting in a large amount of non-carbon nanoparticles not being able to adhere uniformly to the graphite sheets and carbon fiber surfaces, thus leading to poor high-temperature resistance and sealing performance of the resulting material. If the reaction temperature is too high, the growth rate of graphite sheets on the carbon fiber surface is much greater than the adhesion rate of non-carbon nanoparticles on the graphite sheet layer, resulting in uneven distribution of non-carbon nanoparticles on the graphite sheet, which also leads to poor high-temperature resistance and sealing performance of the resulting material.

[0079] In some embodiments, the reaction temperature can be 1500°C, 1800°C, 2000°C, 2200°C, 2500°C, 2800°C, 3000°C, 3200°C, or 3500°C. In a preferred embodiment, the reaction temperature is 1500-3000°C.

[0080] In some embodiments, the reaction time can be 12-720 hours. In a preferred embodiment, the reaction time is 24-120 hours, for example, 24 hours, 48 ​​hours, 72 hours, 80 hours, 100 hours, or 120 hours.

[0081] To ensure that the short-cut carbon fibers, carbon source, specific metal source, and phosphorus source can be used to prepare the aforementioned carbon-carbon composite material, the reaction needs to be carried out under an inert atmosphere. Specifically, the inert atmosphere is nitrogen and / or an inert gas; the purity of the nitrogen and inert gas is >99.9% by volume, and the oxygen content in the inert atmosphere is <50 ppm.

[0082] Without an inert atmosphere for protection during the reaction, it is impossible to obtain a carbon-carbon composite material comprising a single carbon fiber and multiple layers of graphite sheets surrounding the single carbon fiber, with non-carbon nanoparticles adhering to the surface of the single carbon fiber and each graphite sheet. Furthermore, if the volumetric flow rate of the inert atmosphere is too high, a stable microenvironment for the growth of the graphite sheets cannot be maintained, making it even more difficult for non-carbon nanoparticles to adhere to the surface of the carbon fiber or graphite sheets.

[0083] In some embodiments, the volumetric flow rate of the inert atmosphere is 20-1800 mL / min. In a preferred embodiment, the volumetric flow rate of the inert atmosphere is 50-500 mL / min, more preferably 100-300 mL / min.

[0084] In this invention, in order to obtain a carbon-carbon composite material with a suitable ratio of carbon to non-carbon elements, a large number of graphite sheets surrounding the diameter of a single carbon fiber, and excellent high-temperature resistance and sealing performance, the ratio of the amount of chopped carbon fiber, carbon source, metal source and phosphorus source, as well as the ratio of the amount of each metal source, can be appropriately controlled.

[0085] In some embodiments, the weight ratio of the metal source, the phosphorus source, the carbon source, and the chopped carbon fibers is 20-100:3-20:30-200:1, preferably 30-70:5-15:50-150:1;

[0086] The weight ratio of the iron source, the aluminum source, the lead source, the cobalt source, the group IIA element source, and the indium source is 0.8-4:1-4:0.3-1.5:1:0-1:0-0.5.

[0087] In this invention, the non-carbon element source serves to generate non-carbon element nanoparticles, which then adhere to the surfaces of graphite sheets and single carbon fibers to improve the performance of carbon-carbon composite materials. The group IIA element can be a conventional choice in the art; specifically, the group IIA element source is selected from one or more of calcium, strontium, and barium sources, preferably a calcium source.

[0088] In a preferred embodiment, the metal source includes an iron source, an aluminum source, a lead source, a cobalt source, a calcium source, and an indium source. Simultaneously using iron, aluminum, lead, cobalt, calcium, indium, and phosphorus sources as non-carbon element sources can further improve the high-temperature resistance and sealing performance of the prepared carbon-carbon composite material.

[0089] In this invention, the iron source can be a conventional choice in the art, such as an iron salt, iron hydroxide, or iron oxide. Specifically, the iron source is selected from one or more of FeO, Fe2O3, Fe3O4, Fe(OH)2, Fe(OH)3, FeCl2, FeCl3, and FePO4.

[0090] In this invention, the aluminum source can be a conventional choice in the art, such as an aluminum salt, aluminum hydroxide, or aluminum oxide. Specifically, the aluminum source is selected from one or more of Al2O3, AlCl3, Al2(SO4)3, Al(OH)3, and AlPO4.

[0091] In this invention, the lead source can be a conventional choice in the art, such as a lead oxide. Specifically, the lead source is selected from one or more of PbO, Pb3O4, PbO2, and Pb2O3.

[0092] In this invention, the cobalt source can be a conventional choice in the art, such as a cobalt salt, cobalt oxide, or cobalt hydroxide. Specifically, the cobalt source is selected from one or more of CoO, Co(OH)2, CoCl2, and CoSO4.

[0093] In this invention, the calcium source can be a conventional choice in the art, such as a calcium salt, calcium oxide, or calcium hydroxide. Specifically, the calcium source is selected from one or more of CaCl2, CaO, Ca(OH)2, and CaF2.

[0094] In this invention, the indium source can be a conventional choice in the art, such as an indium salt, indium oxide, or indium hydroxide. Specifically, the indium source is selected from one or more of In₂O₃, In(OH)₃, and InCl₃.

[0095] In the method described in this invention, the carbon source serves to form graphite sheets on the outer periphery of a single carbon fiber. The carbon source can be a conventional choice in the art; specifically, it can be a carbonized resin and / or graphite. Preferably, the carbonized resin is a resin-based carbide with a rich porous structure after high-temperature carbonization. Preferably, the graphite is amorphous graphite.

[0096] In this invention, the reaction can be carried out in a conventionally used high-temperature furnace. Specifically, isostatic graphite or highly oriented graphite is used as the heating element in the high-temperature furnace. Preferably, the high-temperature furnace is connected to a tail gas recovery system via a pipeline. A valve is installed on the pipeline connecting the high-temperature furnace and the tail gas recovery system. The inner diameter of the pipeline is between 5-20 mm. A filter screen is installed before the valve along the gas flow direction. The selection of the pipeline, filter screen, and valve meets the temperature resistance requirements.

[0097] In this invention, the single carbon fiber at the center of the carbon-carbon composite material is formed from chopped carbon fibers. In a specific embodiment, the length of the chopped carbon fibers is 0.1-10 mm, preferably 1-5 mm; the K content is 12-320 K, preferably 12-48 K; and the carbon content is 85-95% by weight.

[0098] A third aspect of the present invention provides a carbon-carbon composite material with temperature-resistant sealing properties prepared by the method described above.

[0099] Preferably, the carbon-carbon composite material comprises a single carbon fiber and multiple layers of graphite sheets surrounding the single carbon fiber, wherein non-carbon nanoparticles are attached to the surface of the single carbon fiber and each layer of graphite sheets.

[0100] The non-carbon nanoparticles contain iron, aluminum, phosphorus, lead, cobalt, optional Group IIA elements, and optional indium.

[0101] The fourth aspect of the present invention provides the application of the carbon-carbon composite material with temperature-resistant sealing properties described above as a temperature-resistant sealing material.

[0102] The present invention also provides an apparatus for testing sealing performance, such as... Figure 10 As shown, the device includes a fixing clamp 1, a first container 2, a second container 3, a gas collection bottle 4, a pipe 5, and a sample piece 7. The first container 2 is located below the second container 3. The upper surface of the first container 2 has a first opening, and the lower surface of the second container 3 has a second opening. The sample piece 7 is fixed between the first container 2 and the second container 3 to seal the first opening of the first container 2 and the second opening of the second container 3. The first container 2 has a gas inlet 6. The second container 3 is connected to one end of the pipe 5, and the other end of the pipe 5 is placed in the gas collection bottle 4.

[0103] During the sealing performance test, the gas collection bottle 4 is filled with water. A finely crafted sample piece 7 is fixed between the first container 2 and the second container 3 to seal the first opening of the first container 2 and the second opening of the second container 3. Gas is then introduced through the gas inlet 6. The sealing performance of the carbon-carbon composite material is evaluated by analyzing the number of bubbles per minute in the gas collection bottle 4 to assess the degree of leakage. If the sample piece 7 has good sealing performance, gas cannot enter the second container 3 from the first container 2, resulting in fewer bubbles in the gas collection bottle 4. Conversely, if the sample piece 7 has good sealing performance, there will be more bubbles in the gas collection bottle 4.

[0104] In the apparatus for testing sealing performance described in this invention, such as Figure 10 As shown, the height difference Δh between the end of the pipe 5 in the gas collection bottle 4 and the liquid surface of the gas collection bottle 4 is 10-30mm, preferably 20mm.

[0105] Under preferred conditions, the gas introduced through the gas inlet 6 is nitrogen. Further, the pressure of the introduced nitrogen is 2 MPa.

[0106] Under preferred conditions, the inner diameter of the pipe 5 is 5-12 mm, preferably 8 mm.

[0107] The carbon-carbon composite material described in this invention can be further processed as a raw material. Processing methods include, but are not limited to, blending (extrusion or granulation), strip forming, grinding (pulverizing), and calcination. Material products manufactured using the above processing methods, whose constituent elements and their contents fall within the scope of the claims and description of this invention, are all within the protection scope of this invention. Furthermore, as long as the types and contents of the contained elements are within the scope defined by this invention, regardless of whether they are raw materials or finished products, and the shape of the material is not limited to fibrous form; and it is not limited by the material processing method, they are all within the protection scope of this invention.

[0108] The present invention will be described in detail below through examples, but the scope of protection of the present invention is not limited thereto. Unless otherwise specified, all reagents used in the following examples are commercially available products.

[0109] In the following examples and comparative examples, the carbonized resin powder is YKD-508 blood perfusion carbonized resin (carbon skeleton spherical porous adsorption resin) produced by Henan Yinkai New Material Co., Ltd.

[0110] The testing methods used in this invention include:

[0111] 1. The surface and cross-sectional morphology of the carbon-carbon composite materials prepared in the examples and comparative examples were observed using a ZEISS Merlin field emission scanning electron microscope. The test conditions included: accelerating voltage 20-30 kV and electron beam current 10 pA-40 / 100 / 300 nA.

[0112] 2. The elemental composition, distribution, and particle size of the carbon-carbon composite materials prepared in the examples and comparative examples were analyzed using an X-ray energy dispersive spectroscopy (EDS) instrument configured with a field emission scanning electron microscope (FESS) from ZEISS Merlin, Germany. The area scanning mode testing conditions included: accelerating voltage of 20–30 kV and an effective probe working area of ​​150 mm². 2 The elemental range is Be to U, and the detection limit is approximately 0.1 wt.%.

[0113] 3. Raman Imaging Analysis of Carbon-Carbon Composite Material Cross-Sections: A laser micro-Raman spectrometer (RENISHAW, in-Via Raman microscope, UK, 532nm line, helium-neon laser, laser radiation model: QONTOR) was used to observe the cross-sectional morphology of the carbon-carbon composite materials prepared in the examples and comparative examples, and Raman imaging analysis was performed on the cross-sectional morphology. This allows for high-sensitivity spectral analysis under high-resolution conditions. The specific method includes: directly breaking the carbon-carbon composite material, observing the morphology after the cross-section is exposed, and using Live Track™ technology for real-time focusing. During the test, each point is acquired under focused conditions, and the Z-axis coordinate of each point is recorded to form a surface height image. The Raman imaging results can be superimposed on the height image. The in-situ Raman imaging area is 70µm*70µm, with a step size of 1µm, and the Raman spectrum recording range is 400-3100cm². -1 The integration time for each spectrum is 100 s. The cross-sectional morphology of the fibrous composite material was observed under a 20x objective lens, and Raman spectra were acquired at a specific location within a 1 μm x 1 μm region. This spectrum has a range of 1350 cm⁻¹. -1 Nearby D peak, 1582cm -1 Nearby G peak, and 2699cm -1 Nearby 2D peaks; also using Raman imaging, observe the intensity distribution of the D peaks at different points.

[0114] 4. The types and contents of non-carbon elements in the carbon-carbon composite materials prepared in the examples and comparative examples were tested using inductively coupled plasma atomic emission spectrometry.

[0115] The main instruments and reagents are as follows:

[0116] (1) Varian 725-ES inductively coupled plasma atomic emission spectrometer;

[0117] (2) Haoyue HMF1600-40 box furnace;

[0118] (3) LabTech Digiblock ST36 electrothermal digester;

[0119] (4) Multi-element standard solution: 1000ug / mL (Steel Research Institute Nake Testing Technology Co., Ltd.); Praseodymium standard stock solution: 1000ug / mL (National Nonferrous Metals and Electronic Materials Analysis and Testing Center); Vanadium standard stock solution: 1000ug / mL (National Nonferrous Metals and Electronic Materials Analysis and Testing Center); The ultrapure water used in the experiment was prepared by the Genie Purist intelligent ultrapure water system (resistivity = 18.2MΩcm, 25℃); Hydrogen peroxide (30wt%), hydrochloric acid, nitric acid and hydrofluoric acid were all of superior purity; Sulfuric acid was of process ultrapure purity (Sinopharm Chemical Reagent Co., Ltd.); Liquid argon (Chart Cryogenic Engineering Systems (Changzhou) Co., Ltd.).

[0120] The instrument's operating conditions are as follows:

[0121] Instrument operating parameters: High-frequency power: 1100W; Plasma gas flow rate: 15L / min -1 Auxiliary gas flow rate: 1.5 L / min -1 Atomizing gas flow rate: 0.75L / min -1 Sample injection pump speed: 15 rpm; observation height: 10 mm.

[0122] The experimental method is as follows:

[0123] (1) Accurately weigh 0.1g of sample into a clean quartz crucible, place it in a box furnace, and gradually heat it to 930℃ for ashing treatment to obtain ash. The percentage of weight loss of the sample during the calcination process is the carbon content of the fibrous carbon-carbon composite material in this patent;

[0124] (2) Use a small amount of ultrapure water to transfer all the ash to a PFA test tube, add aqua regia, hydrogen peroxide, sulfuric acid and hydrofluoric acid in sequence, cover and place in an electric digestion apparatus to heat until the sample is completely digested;

[0125] (3) Remove the test tube and cool it to room temperature. Transfer it to a 50 mL volumetric flask using ultrapure water and make up to volume for testing.

[0126] (4) Prepare mixed standard solutions of elements, plot test spectra, use inductively coupled plasma atomic emission spectrometer to detect the test solution, and calculate the content of each element according to the plotted test spectra.

[0127] Example 1

[0128] Methods for preparing carbon-carbon composite materials include:

[0129] Short-cut carbon fibers (12K specification, 3mm length, 90% carbon content by weight), carbonized resin powder, metal source, and phosphorus source (AlPO4) were reacted in a high-temperature furnace for 48 hours in the presence of nitrogen.

[0130] The weight ratio of metal source, phosphorus source, carbonized resin powder, and chopped carbon fiber is 50:7:100:1, and the weight ratio of metal sources Fe2O3, Al2O3, Pb3O4, Co(OH)2, CaF2, and In2O3 is 1.7:1.3:1:1:0.2:0.1.

[0131] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2200℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 40 ppm, and a gas flow rate of 100 mL / min.

[0132] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0133] The carbon-carbon composite material prepared in this embodiment (macromorphological diagram as shown) Figure 1 As shown), it has the following characteristics:

[0134] (1) As Figure 9 As shown, the center consists of a single carbon fiber with a diameter of 5 μm and a length of 3 mm. The single carbon fiber is surrounded by nine concentric graphite sheets, with the thickness of each sheet gradually increasing from the inside out. The total thickness of the nine graphite sheets is in a 19:1 ratio to the diameter of the single carbon fiber. Non-carbon nanoparticles are attached to the surface of the single carbon fiber and each graphite sheet. The carbon-carbon composite material has a diameter of 0.2 mm and a length of 3 mm.

[0135] (2) The carbon-carbon composite material is gray, and each graphite sheet and single carbon fiber has independently existing carbon particles distributed on its surface. The particle size of the carbon particles is 0.07 mm. The carbon-carbon composite material is curved in the axial direction, and some surfaces have blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.161:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.484:1.

[0136] (3) The main elements contained in carbon-carbon composite materials include: C content of 59 wt%; Fe content of 5.0 wt%; Al content of 4.0 wt%; P content of 2.1 wt%; Pb content of 2.6 wt%; Co content of 2.8 wt%; Ca content of 0.5 wt%; In content of 0.3 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0137] The features of steps (1) and (2) were obtained by analysis using a ZEISS Merlin field emission scanning electron microscope and an X-ray energy dispersive spectrometer configured with a ZEISS Merlin field emission scanning electron microscope.

[0138] from Figures 2-8 As can be seen from the elemental energy spectrum, the Fe(II) in the composite material prepared in this embodiment is... Figure 2 Al( Figure 3 ), P( Figure 4 ), Pb( Figure 5 ), Co ( Figure 6 ), Ca( Figure 7 ) and In( Figure 8 It is uniformly distributed and consists of nanoparticles.

[0139] Example 2

[0140] Methods for preparing carbon-carbon composite materials include:

[0141] Short-cut carbon fibers (24K specification, 6mm length, 95% carbon content by weight), amorphous graphite, a metal source, and a phosphorus source (Al(PO3)3) were reacted in a high-temperature furnace for 100 hours in the presence of nitrogen.

[0142] The weight ratio of the metal source, phosphorus source, amorphous graphite, and chopped carbon fibers is 33:5:70:1, and the weight ratio of the metal sources FeCl3, AlCl3, Pb2O3, CoCl2, CaCl2, and InCl3 is 2.4:2:1:1:0.2:0.2.

[0143] The high-temperature furnace uses highly oriented graphite as the heating element. The furnace operates at a core temperature of 2200℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 40 ppm, and a gas flow rate of 200 mL / min.

[0144] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 5mm, and a filter screen is installed before the valve along the gas flow direction.

[0145] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0146] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 6 mm; the outer periphery of the single carbon fiber is surrounded by 7 layers of concentric graphite sheets, the thickness of the 7 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 7 graphite sheets to the diameter of the single carbon fiber is 38:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.4 mm and a length of 6 mm.

[0147] (2) The carbon-carbon composite material is black, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 1.3 mm. The carbon-carbon composite material is linear in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.163:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.477:1.

[0148] (3) The main elements contained in carbon-carbon composite materials include: C content of 63 wt%; Fe content of 6.7 wt%; Al content of 5.5 wt%; P content of 3.1 wt%; Pb content of 3.3 wt%; Co content of 3.2 wt%; Ca content of 0.7 wt%; In content of 0.6 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0149] Example 3

[0150] Methods for preparing carbon-carbon composite materials include:

[0151] Short-cut carbon fibers (50K specification, 9mm length, 90% carbon content), carbonized resin powder, metal source, and phosphorus source (AlPO4) were reacted in a high-temperature furnace for 80 hours in the presence of nitrogen.

[0152] The weight ratio of the metal source, phosphorus source, carbonized resin powder, and chopped carbon fibers is 25:4:50:1, and the weight ratio of the metal sources Fe2O3, Al2O3, Pb3O4, Co(OH)2, CaF2, and In2O3 is 2.75:1.25:1:1:0.25:0.25.

[0153] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2800℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 40 ppm, and a gas flow rate of 400 mL / min.

[0154] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 15mm, and a filter screen is installed before the valve along the gas flow direction.

[0155] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0156] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 9 mm; the outer periphery of the single carbon fiber is surrounded by 7 layers of concentric graphite sheets, the thickness of the 7 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 7 graphite sheets to the diameter of the single carbon fiber is 39:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.4 mm and a length of 9 mm.

[0157] (2) The carbon-carbon composite material is gray, and each graphite sheet and single carbon fiber has independently existing carbon particles distributed on its surface. The particle size of the carbon particles is 0.08 mm. The carbon-carbon composite material is linear in the axial direction, and some of its surfaces are bamboo-like. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of the D peak to the G peak is 0.183:1, and the average ratio of the peak intensity of the 2D peak to the G peak is 0.554:1.

[0158] (3) The main elements contained in carbon-carbon composite materials include: C content of 55 wt%; Fe content of 8.2 wt%; Al content of 4.0 wt%; P content of 3.1 wt%; Pb content of 2.9 wt%; Co content of 3.0 wt%; Ca content of 0.4 wt%; In content of 0.8 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0159] Example 4

[0160] Methods for preparing carbon-carbon composite materials include:

[0161] Short-cut carbon fibers (12K specification, 6mm length, 95% carbon content), amorphous graphite, metal source, and phosphorus source (Al(PO3)3) were reacted in a high-temperature furnace for 150 hours in the presence of nitrogen.

[0162] The weight ratio of the metal source, phosphorus source, amorphous graphite, and chopped carbon fibers is 32:4:65:1, and the weight ratio of the metal sources FeCl3, AlCl3, Pb2O3, CoCl2, CaCl2, and InCl3 is 2.5:2:1.5:1:0.25:0.25.

[0163] The high-temperature furnace uses isostatically pressed graphite as the heating element. The core operating temperature of the high-temperature furnace is 2800℃, the nitrogen purity is 99.99% by volume, the oxygen concentration is 40ppm, and the gas flow rate is 500mL / min.

[0164] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 20mm, and a filter screen is installed before the valve along the gas flow direction.

[0165] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0166] (1) The center is a single carbon fiber with a diameter of 7 μm and a length of 6 mm; the outer periphery of the single carbon fiber is surrounded by 12 layers of concentric graphite sheets, the thickness of the 12 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 12 graphite sheets to the diameter of the single carbon fiber is 43:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.6 mm and a length of 6 mm.

[0167] (2) The carbon-carbon composite material is black, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 1.1 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surface is covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.179:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.553:1.

[0168] (3) The main elements contained in carbon-carbon composite materials include: C content of 68 wt%; Fe content of 7.5 wt%; Al content of 6.3 wt%; P content of 2.9 wt%; Pb content of 4.2 wt%; Co content of 3.1 wt%; Ca content of 0.6 wt%; In content of 0.8 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0169] Example 5

[0170] Methods for preparing carbon-carbon composite materials include:

[0171] Short-cut carbon fibers (12K specification, 6mm length, 95% carbon content by weight), amorphous graphite, a metal source, and a phosphorus source (Al(PO3)3) were reacted in a high-temperature furnace for 36 hours in the presence of nitrogen.

[0172] The weight ratio of the metal source, phosphorus source, amorphous graphite, and chopped carbon fibers is 23:3:45:1, and the weight ratio of the metal sources FeCl3, AlCl3, Pb2O3, CoCl2, CaCl2, and InCl3 is 2:2:1:1:0.33:0.33.

[0173] The high-temperature furnace uses isostatically pressed graphite as the heating element. The core operating temperature of the high-temperature furnace is 2800℃, the nitrogen purity is 99.99% by volume, the oxygen concentration is 40ppm, and the gas flow rate is 50mL / min.

[0174] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0175] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0176] (1) The center is a single carbon fiber with a diameter of 7 μm and a length of 6 mm; the outer periphery of the single carbon fiber is surrounded by 17 layers of concentric graphite sheets, the thickness of the 17 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 17 graphite sheets to the diameter of the single carbon fiber is 65:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.9 mm and a length of 6 mm.

[0177] (2) The carbon-carbon composite material is black, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 1.2 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surface is covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.188:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.556:1.

[0178] (3) The main elements contained in carbon-carbon composite materials include: C content of 80 wt%; Fe content of 3.3 wt%; Al content of 3.2 wt%; P content of 1.5 wt%; Pb content of 1.7 wt%; Co content of 1.9 wt%; Ca content of 0.5 wt%; In content of 0.6 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0179] Example 6

[0180] Methods for preparing carbon-carbon composite materials include:

[0181] Short-cut carbon fibers (12K specification, 6mm length, 95% carbon content), amorphous graphite, metal source, and phosphorus source (Al(PO3)3) were reacted in a high-temperature furnace for 120 hours in the presence of nitrogen.

[0182] The weight ratio of the metal source, phosphorus source, amorphous graphite, and chopped carbon fibers is 31:6:65:1, and the weight ratio of the metal sources FeCl3, AlCl3, Pb2O3, CoCl2, CaCl2, and InCl3 is 0.8:1.43:1:1:0.14:0.14.

[0183] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2800℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 20 ppm, and a gas flow rate of 100 mL / min.

[0184] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0185] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0186] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 6 mm; the outer periphery of the single carbon fiber is surrounded by 18 layers of concentric graphite sheets, the thickness of the 18 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 18 graphite sheets to the diameter of the single carbon fiber is 95:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 1 mm and a length of 6 mm.

[0187] (2) The carbon-carbon composite material is black, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 1.5 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.186:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.554:1.

[0188] (3) The main elements contained in carbon-carbon composite materials include: C content of 74 wt%; Fe content of 4.0 wt%; Al content of 7.2 wt%; P content of 4.2 wt%; Pb content of 4.4 wt%; Co content of 4.6 wt%; Ca content of 0.3 wt%; In content of 0.7 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0189] Example 7

[0190] Methods for preparing carbon-carbon composite materials include:

[0191] Short-cut carbon fibers (12K specification, 6mm length, 95% carbon content by weight), amorphous graphite, a metal source, and a phosphorus source (Al(PO3)3) were reacted in a high-temperature furnace for 144 hours in the presence of nitrogen.

[0192] The weight ratio of the metal source, phosphorus source, amorphous graphite, and chopped carbon fibers is 29:6:60:1, and the weight ratio of the metal sources FeCl3, AlCl3, Pb2O3, CoCl2, CaCl2, and InCl3 is 1.6:1.4:1:1:0.2:0.2.

[0193] The high-temperature furnace uses isostatically pressed graphite as the heating element. The core operating temperature of the high-temperature furnace is 2800℃, the nitrogen purity is 99.99% by volume, the oxygen concentration is 20ppm, and the gas flow rate is 200mL / min.

[0194] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0195] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0196] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 6 mm; the outer periphery of the single carbon fiber is surrounded by 12 layers of concentric graphite sheets, the thickness of the 12 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 12 graphite sheets to the diameter of the single carbon fiber is 38:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.4 mm and a length of 6 mm.

[0197] (2) The carbon-carbon composite material is black, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 0.6 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.184:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.555:1.

[0198] (3) The main elements contained in carbon-carbon composite materials include: C content of 63 wt%; Fe content of 7.0 wt%; Al content of 5.9 wt%; P content of 4.7 wt%; Pb content of 4.3 wt%; Co content of 4.0 wt%; Ca content of 0.4 wt%; In content of 0.9 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0199] Example 8

[0200] Methods for preparing carbon-carbon composite materials include:

[0201] Short-cut carbon fibers (12K specification, 6mm length, 95% carbon content by weight), amorphous graphite, a metal source, and a phosphorus source (Al(PO3)3) were reacted in a high-temperature furnace for 72 hours in the presence of nitrogen.

[0202] The weight ratio of the metal source, phosphorus source, amorphous graphite, and chopped carbon fibers is 53:8:110:1, and the weight ratio of the metal sources FeCl3, AlCl3, Pb2O3, CoCl2, CaCl2, and InCl3 is 2.85:1.43:1.14:1:0.14:0.14.

[0203] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2800℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 20 ppm, and a gas flow rate of 400 mL / min.

[0204] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0205] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0206] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 6 mm; the outer periphery of the single carbon fiber is surrounded by 13 layers of concentric graphite sheets, the thickness of the 13 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 13 graphite sheets to the diameter of the single carbon fiber is 49:1; non-carbon element nanoparticles are filled between any two adjacent graphite sheets; the carbon-carbon composite material has a diameter of 0.5 mm and a length of 6 mm.

[0207] (2) The carbon-carbon composite material is black, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 1 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.183:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.555:1.

[0208] (3) The main elements contained in carbon-carbon composite materials include: C content of 52 wt%; Fe content of 9.0 wt%; Al content of 3.9 wt%; P content of 2.9 wt%; Pb content of 3.1 wt%; Co content of 2.5 wt%; Ca content of 0.1 wt%; In content of 0.4 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0209] Example 9

[0210] Methods for preparing carbon-carbon composite materials include:

[0211] Short-cut carbon fibers (12K specification, 6mm length, 95% carbon content by weight), amorphous graphite, a metal source, and a phosphorus source (Al(PO3)3) were reacted in a high-temperature furnace for 48 hours in the presence of nitrogen.

[0212] The weight ratio of the metal source, phosphorus source, amorphous graphite, and chopped carbon fibers is 79:4:160:1, and the weight ratio of the metal sources FeCl3, AlCl3, Pb2O3, CoCl2, CaCl2, and InCl3 is 4:4:0.4:1:0.8:0.2.

[0213] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2800℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 20 ppm, and a gas flow rate of 500 mL / min.

[0214] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0215] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0216] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 6 mm; the outer periphery of the single carbon fiber is surrounded by 16 layers of concentric graphite sheets, the thickness of the 16 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 16 graphite sheets to the diameter of the single carbon fiber is 89:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.9 mm and a length of 6 mm.

[0217] (2) The carbon-carbon composite material is black, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 1.2 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surface is covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.179:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.554:1.

[0218] (3) The main elements contained in carbon-carbon composite materials include: C content of 72 wt%; Fe content of 8.0 wt%; Al content of 5.9 wt%; P content of 0.8 wt%; Pb content of 0.2 wt%; Co content of 0.6 wt%; Ca content of 0.7 wt%; In content of 0.2 wt%; and elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0219] Example 10

[0220] The method of Example 1 is implemented, except that the metal source is an iron source, an aluminum source, a lead source, a cobalt source, and an indium source, but does not contain a calcium source.

[0221] Methods for preparing carbon-carbon composite materials include:

[0222] Short-cut carbon fibers (12K specification, 3mm length, 90% carbon content by weight), carbonized resin powder, metal source, and phosphorus source (AlPO4) were reacted in a high-temperature furnace for 48 hours in the presence of nitrogen.

[0223] The weight ratio of metal source, phosphorus source, carbonized resin powder, and chopped carbon fiber is 50:7:100:1, and the weight ratio of metal sources Fe2O3, Al2O3, Pb3O4, Co(OH)2, and In2O3 is 1.75:1.38:1:1:0.13.

[0224] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2200℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 40 ppm, and a gas flow rate of 100 mL / min.

[0225] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0226] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0227] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 3 mm; the outer periphery of the single carbon fiber is surrounded by 9 layers of concentric graphite sheets, the thickness of the 9 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 9 graphite sheets to the diameter of the single carbon fiber is 19:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.2 mm and a length of 3 mm.

[0228] (2) The carbon-carbon composite material is gray, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 0.07 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.182:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.553:1.

[0229] (3) The main elements contained in carbon-carbon composite materials include: C content of 58 wt%; Fe content of 5.2 wt%; Al content of 4.4 wt%; P content of 2.3 wt%; Pb content of 2.8 wt%; Co content of 2.9 wt%; In content of 0.4 wt%; and elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0230] Example 11

[0231] The method of Example 1 is implemented, except that the metal source is an iron source, an aluminum source, a lead source, a cobalt source, and a calcium source, but does not contain an indium source.

[0232] Methods for preparing carbon-carbon composite materials include:

[0233] Short-cut carbon fibers (12K specification, 3mm length, 90% carbon content by weight), carbonized resin powder, metal source, and phosphorus source (AlPO4) were reacted in a high-temperature furnace for 48 hours in the presence of nitrogen.

[0234] The weight ratio of metal source, phosphorus source, carbonized resin powder, and chopped carbon fiber is 50:7:100:1, and the weight ratio of metal sources Fe2O3, Al2O3, Pb3O4, Co(OH)2, and CaF2 is 1.75:1.25:1:1:0.25.

[0235] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2200℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 40 ppm, and a gas flow rate of 100 mL / min.

[0236] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0237] The carbon-carbon composite material prepared in this embodiment has the following characteristics:

[0238] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 3 mm; the outer periphery of the single carbon fiber is surrounded by 9 layers of concentric graphite sheets, the thickness of the 9 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 9 graphite sheets to the diameter of the single carbon fiber is 19:1; the surface of the single carbon fiber and each layer of graphite sheets is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.2 mm and a length of 3 mm.

[0239] (2) The carbon-carbon composite material is gray, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 0.07 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surface is covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.180:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.550:1.

[0240] (3) The main elements contained in carbon-carbon composite materials include: C content of 57 wt%; Fe content of 5.2 wt%; Al content of 4.1 wt%; P content of 2.1 wt%; Pb content of 2.8 wt%; Co content of 3.2 wt%; Ca content of 0.8 wt%; and elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0241] Comparative Example 1

[0242] The method was implemented according to Example 1, except that short-cut carbon fibers were not added into the high-temperature furnace.

[0243] Because this comparative example lacks short-cut carbon fibers, non-carbon element particles cannot form growth attachment points. Carbon vapor can only grow into blocky carbon-containing substances with extremely high carbon content on the surface of the inner wall of the high-temperature furnace, and the carbon-carbon composite material described in this invention cannot be obtained.

[0244] The material obtained in this comparative example is a blocky product formed from a carbon source. The material contains 99.9% by weight of carbon and does not contain iron, aluminum, phosphorus, lead, cobalt, calcium, or indium.

[0245] Comparative Example 2

[0246] The method of Example 1 was followed, except that the reaction process was not protected by an inert atmosphere.

[0247] Without an inert atmosphere for protection, the carbonized resin powder oxidizes into carbon dioxide, and the short-cut carbon fibers with higher temperature resistance break into short-cut carbon fibers with uneven shapes and oxidized and etched surfaces. It is impossible to form a concentric circle structure with multiple layers of graphite sheets surrounding a single carbon fiber, nor can it fill non-carbon element particles. Therefore, the carbon-carbon composite material described in this invention cannot be obtained.

[0248] The material prepared in this comparative example contains 99.9% by weight carbon and does not contain iron, aluminum, phosphorus, lead, cobalt, calcium, or indium.

[0249] Comparative Example 3

[0250] The method was implemented according to Example 1, except that carbonized resin powder and non-carbon element sources were not added to the high-temperature furnace.

[0251] The material obtained in this comparative example is a product formed from short-cut carbon fibers. The material contains 99.9% by weight of carbon and does not contain iron, aluminum, phosphorus, lead, cobalt, calcium, or indium. Therefore, it does not yield the carbon-carbon composite material described in this invention.

[0252] Comparative Example 4

[0253] The method was implemented according to Example 1, except that the center temperature was 1200°C.

[0254] In this comparative example, the temperature was too low, which prevented the carbon in the carbonized resin powder from growing further on the surface of a single carbon fiber. At the same time, non-carbon element particles could not adhere to the surface of the carbon fiber or graphite sheet, thus failing to obtain the carbon-carbon composite material described in this invention.

[0255] The material prepared in this comparative example is a mixture formed by the independent reaction of short-cut carbon fibers, carbonized resin powder, and metal source.

[0256] Comparative Example 5

[0257] The method was carried out according to Example 1, except that the gas flow rate was 2000 mL / min.

[0258] In this comparative example, due to the excessive gas flow rate, the microenvironment for stable growth of graphite sheets could not be maintained, and non-carbon element particles could not adhere to the surface of carbon fibers or graphite sheets, thus failing to obtain the carbon-carbon composite material described in this invention.

[0259] The material prepared in this comparative example is a mixture formed by the independent reaction of short-cut carbon fibers, carbonized resin powder, and metal source.

[0260] Comparative Example 6

[0261] The method was implemented according to Example 1, except that no phosphorus source was added to the high-temperature furnace.

[0262] The carbon-carbon composite material prepared in this comparative example has the following characteristics:

[0263] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 3 mm; the outer periphery of the single carbon fiber is surrounded by 9 layers of concentric graphite sheets, the thickness of the 9 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 9 graphite sheets to the diameter of the single carbon fiber is 19:1; nano-metal particles are filled between any two adjacent graphite sheets; the carbon-carbon composite material has a diameter of 0.2 mm and a length of 3 mm.

[0264] (2) The carbon-carbon composite material is gray. Carbon particles are present on the surface of the carbon-carbon composite material, and the particle size of the carbon particles is 0.07 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.160:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.481:1.

[0265] (3) The main elements contained in carbon-carbon composite materials include: C content of 59 wt%; Fe content of 5.0 wt%; Al content of 3.9 wt%; Pb content of 2.6 wt%; Co content of 2.8 wt%; Ca content of 0.5 wt%; In content of 0.3 wt%; and elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0266] Comparative Example 7

[0267] The method was implemented according to Example 1, except that no metal source was added to the high-temperature furnace.

[0268] The carbon-carbon composite material prepared in this comparative example has the following characteristics:

[0269] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 3 mm; the outer periphery of the single carbon fiber is surrounded by 9 layers of concentric graphite sheets, the thickness of the 9 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 9 graphite sheets to the diameter of the single carbon fiber is 19:1; nano-metal particles are filled between any two adjacent graphite sheets; the carbon-carbon composite material has a diameter of 0.2 mm and a length of 3 mm.

[0270] (2) The carbon-carbon composite material is gray. Carbon particles are present on the surface of the carbon-carbon composite material, and the particle size of the carbon particles is 0.07 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.159:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.479:1.

[0271] (3) The main elements contained in carbon-carbon composite materials include: carbon content of 99.9% by weight; elements with content less than 0.001% by weight include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0272] Comparative Example 8

[0273] The method was implemented according to Example 1, except that no lead source Pb3O4 was added to the high-temperature furnace.

[0274] Methods for preparing carbon-carbon composite materials include:

[0275] In the presence of nitrogen, short-cut carbon fibers (12K specification, 3mm length, 90% carbon content by weight), the carbonized resin powder, the metal source, and the phosphorus source (AlPO4) were reacted in a high-temperature furnace for 48 hours.

[0276] The weight ratio of metal source, phosphorus source, carbonized resin powder, and chopped carbon fiber is 50:7:100:1, and the weight ratio of the metal sources Fe2O3, Al2O3, Co(OH)2, CaF2, and In2O3 is 1.5:1.17:1:0.33:0.17.

[0277] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2200℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 40 ppm, and a gas flow rate of 100 mL / min.

[0278] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0279] The carbon-carbon composite material prepared in this comparative example has the following characteristics:

[0280] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 3 mm; the outer periphery of the single carbon fiber is surrounded by 9 layers of concentric graphite sheets, the thickness of the 9 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 9 graphite sheets to the diameter of the single carbon fiber is 19:1; non-carbon element nanoparticles are filled between any two adjacent graphite sheets; the carbon-carbon composite material has a diameter of 0.2 mm and a length of 3 mm.

[0281] (2) The carbon-carbon composite material is gray, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 0.07 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.183:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.547:1.

[0282] (3) The main elements contained in carbon-carbon composite materials include: C content of 58 wt%; Fe content of 5.1 wt%; Al content of 4.2 wt%; P content of 2.0 wt%; Co content of 3.3 wt%; Ca content of 0.9 wt%; In content of 0.6 wt%; and elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0283] Comparative Example 9

[0284] The method was implemented according to Example 1, except that no cobalt source Co(OH)2 was added to the high-temperature furnace.

[0285] Methods for preparing carbon-carbon composite materials include:

[0286] Short-cut carbon fibers (12K specification, 3mm length, 90% carbon content by weight), carbonized resin powder, metal source, and phosphorus source (AlPO4) were reacted in a high-temperature furnace for 48 hours in the presence of nitrogen.

[0287] The weight ratio of metal source, phosphorus source, carbonized resin powder, and chopped carbon fiber is 50:7:100:1, and the weight ratio of metal sources Fe2O3, Al2O3, Pb3O4, CaF2, and In2O3 is 1.75:1.5:1:0.5:0.25.

[0288] The high-temperature furnace uses isostatically pressed graphite as the heating element. The furnace operates at a core temperature of 2200℃, with nitrogen purity of 99.99% by volume, oxygen concentration of 40 ppm, and a gas flow rate of 100 mL / min.

[0289] A valve is installed on the pipe connecting the high-temperature furnace and the exhaust gas recovery system. The valve is fully open, the pipe has an inner diameter of 10mm, and a filter screen is installed before the valve along the gas flow direction.

[0290] The carbon-carbon composite material prepared in this comparative example has the following characteristics:

[0291] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 3 mm; the outer periphery of the single carbon fiber is surrounded by 9 layers of concentric graphite sheets, the thickness of the 9 graphite sheets gradually increases from the inside to the outside, and the ratio of the total thickness of the 9 graphite sheets to the diameter of the single carbon fiber is 19:1; non-carbon element nanoparticles are filled between any two adjacent graphite sheets; the carbon-carbon composite material has a diameter of 0.2 mm and a length of 3 mm.

[0292] (2) The carbon-carbon composite material is gray, and there are carbon particles on the surface of the carbon-carbon composite material with a particle size of 0.07 mm. The carbon-carbon composite material is curved in the axial direction, and some of the surfaces are covered with blocky protrusions. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.182:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.552:1.

[0293] (3) The main elements contained in carbon-carbon composite materials include: C content of 56 wt%; Fe content of 5.4 wt%; Al content of 4.3 wt%; P content of 2.2 wt%; Pb content of 3.0 wt%; Ca content of 1.0 wt%; In content of 0.8 wt%; Elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0294] Comparative Example 10

[0295] The method was carried out according to Example 1, except that the gas flow rate was 10 mL / min.

[0296] The carbon-carbon composite material prepared in this comparative example has the following characteristics:

[0297] (1) The center is a single carbon fiber with a diameter of 5 μm and a length of 3 mm; the outer periphery of the single carbon fiber is surrounded by two concentric graphite sheets with the thickness of the two graphite sheets gradually increasing from the inside to the outside, and the ratio of the total thickness of the two graphite sheets to the diameter of the single carbon fiber is 3:1; the surface of the single carbon fiber and each graphite sheet is coated with non-carbon element nanoparticles; the carbon-carbon composite material has a diameter of 0.03 mm and a length of 3 mm.

[0298] (2) The carbon-carbon composite material is gray. Carbon particles are present on the surface of the carbon-carbon composite material, and the particle size of the carbon particles is 0.02 mm. The carbon-carbon composite material is curved in the axial direction, and blocky protrusions are distributed on some surfaces. In the Raman imaging spectrum of the carbon-carbon composite material, the average ratio of the peak intensity of D peak to G peak is 0.161:1, and the average ratio of the peak intensity of 2D peak to G peak is 0.474:1.

[0299] (3) The main elements contained in carbon-carbon composite materials include: C content of 94 wt%; Fe content of 0.4 wt%; Al content of 0.1 wt%; P content of 0.1 wt%; Pb content of 0.05 wt%; Co content of 0.02 wt%; Ca content of 0.03 wt%; In content of 0.02 wt%; and elements with a content of less than 0.001 wt% include: zinc, manganese, silver, barium, copper, lithium, magnesium and strontium.

[0300] Test case

[0301] 1. The temperature resistance properties of the materials prepared in the examples and comparative examples were tested according to the following method. The results are shown in Table 1.

[0302] Weigh approximately 3g of material in a high-temperature crucible and record the mass of the material as m1. (1) Place the material in a muffle furnace for heat treatment (air atmosphere, the same below), at a treatment temperature of 500℃, hold for 2 hours, and then allow it to cool naturally; (2) Treat the material at 800℃, hold for 2 hours, allow it to cool naturally, remove it, weigh it, and record the mass of the material as m2. The thermal weight loss rate (w, expressed as a percentage) of the material is used to represent its temperature resistance. The smaller the thermal weight loss rate, the better the temperature resistance.

[0303] The thermal weight loss rate of a material is expressed by the following formula:

[0304]

[0305] 2. The sealing performance of the materials prepared in the examples and comparative examples was tested according to the following method. The results are shown in Table 1.

[0306] After pressing the material into sample pieces with a diameter of 25mm and a thickness of 15mm, it undergoes fine processing and grinding of all surfaces. In such cases... Figure 10 In the apparatus shown for testing sealing performance, a finely crafted sample 7 is fixed between the first container 2 and the second container 3. Nitrogen gas at 2.0 MPa is introduced through the gas inlet 6. The second container 3 is connected to one end of a pipe 5 with an inner diameter of 8 mm, and the other end of the pipe 5 is placed in a gas collection bottle 4 filled with pure water (the height difference Δh between the end of the pipe 5 and the liquid level in the gas collection bottle 4 is 20 mm). In this test, the degree of leakage of the sample seal is analyzed by the number of air bubbles per minute in the gas collection bottle 4.

[0307] Table 1

[0308]

[0309] As can be seen from Table 1, the material prepared using the technical solution described in this invention has a low thermal weight loss rate and good high-temperature resistance; the number of bubbles collected per minute is small, and the sealing performance is good.

[0310] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A carbon-carbon composite material having temperature resistant sealing properties, characterized by, The carbon-carbon composite material comprises single carbon fibers and multi-layered graphite sheets surrounding the periphery of the single carbon fibers, and the surface of the single carbon fibers and each graphite sheet is attached with non-carbon element nanoparticles, The non-carbon element nanoparticles contain iron, aluminum, phosphorus, lead, cobalt, group IIA elements and indium. The carbon-carbon composite material contains 50-90 wt% of carbon, 0.5-10 wt% of iron, 0.5-10 wt% of aluminum, 0.2-5 wt% of phosphorus, 0.2-5 wt% of lead, 0.2-5 wt% of cobalt, 0-1 wt% of group IIA elements and 0-1 wt% of indium.

2. The carbon-carbon composite material of claim 1, wherein The carbon-carbon composite material contains 56-80 wt% of carbon, 5-8 wt% of iron, 4-8 wt% of aluminum, 1-3.5 wt% of phosphorus, 1-3.5 wt% of lead, 0.5-3.5 wt% of cobalt, 0.2-0.8 wt% of group IIA elements and 0.2-0.8 wt% of indium.

3. The carbon-carbon composite material according to claim 1 or 2, characterized in that, The group IIA elements are selected from one or more of calcium, strontium and barium.

4. The carbon-carbon composite of claim 1, wherein The non-carbon element nanoparticles contain iron, aluminum, phosphorus, lead, cobalt, calcium and indium.

5. The carbon-carbon composite of claim 1, wherein The number of layers of graphite sheets surrounding the periphery of the single carbon fibers is 3-20 layers.

6. The carbon-carbon composite of claim 5, wherein The number of layers of graphite sheets surrounding the periphery of the single carbon fibers is 6-12 layers.

7. The carbon-carbon composite of claim 1, wherein The diameter of the single carbon fibers is 4-8 um; and the length is 2-10 mm.

8. The carbon-carbon composite of claim 7, wherein The diameter of the single carbon fibers is 4.5-7.5 um.

9. The carbon-carbon composite of claim 7, wherein The length of the single carbon fibers is 3-9 mm.

10. The carbon-carbon composite of claim 1, wherein The thickness of the multi-layered graphite sheets gradually increases from inside to outside.

11. The carbon-carbon composite material according to claim 1 or 10, wherein The ratio of the total thickness of the multi-layered graphite sheets to the diameter of the single carbon fibers is 1-100:

1.

12. The carbon-carbon composite of claim 1, wherein, The carbon-carbon composite material is in a straight line and / or a curved shape.

13. The carbon-carbon composite of claim 1 or 12, wherein At least part of the surface of the carbon-carbon composite material is in a bamboo joint shape and / or a convex shape.

14. The carbon-carbon composite of claim 1, wherein, The diameter of the carbon-carbon composite material is 0.05-1 mm; and the length is 0.1-10 mm.

15. The carbon-carbon composite of claim 14, wherein, The diameter of the carbon-carbon composite material is 0.1-0.3 mm.

16. The carbon-carbon composite of claim 14, wherein The diameter of the carbon-carbon composite material is 1-5 mm.

17. The carbon-carbon composite of claim 1, wherein In the Raman spectrum of the carbon-carbon composite material, the ratio of the peak intensity of the D peak to the G peak is 0.07-0.3:

1.

18. The carbon-carbon composite of claim 1, wherein, In the Raman spectrum of the carbon-carbon composite material, the ratio of the peak intensity of the 2D peak to the G peak is 0.2-0.9:

1.

19. A method of making a carbon-carbon composite material having temperature resistant sealing properties, characterized by, The method comprises: reacting chopped carbon fibers, a carbon source, a metal source and a phosphorus source at 1500-3500℃ in the presence of an inert atmosphere, and the volume flow rate of the inert atmosphere is 20-1800 mL / min; The metal source contains iron, aluminum, lead, cobalt, group IIA elements and indium. The weight ratio of the amount of the metal source, the phosphorus source, the carbon source and the chopped carbon fibers is 20-100:3-20:30-200:

1. The weight ratio of the amount of the iron source, the aluminum source, the lead source, the cobalt source, the group IIA element source and the indium source is 0.8-4:1-4:0.3-1.5:1:0-1:0-0.

5.

20. The method of claim 19, wherein, The weight ratio of the metal source, the phosphorus source, the carbon source and the chopped carbon fiber is 30-70:5-15:50-150:

1.

21. The method of claim 19 or 20, wherein, The group IIA element source is selected from one or more of a calcium source, a strontium source and a barium source.

22. The method of claim 21, wherein, The metal source contains an iron source, an aluminum source, a lead source, a cobalt source, a calcium source and an indium source.

23. The method of claim 22, wherein, The iron source is selected from one or more of FeO, Fe2O3, Fe3O4, Fe(OH)2, Fe(OH)3, FeCl2, FeCl3 and FePO4.

24. The method of claim 22, wherein, The aluminum source is selected from one or more of Al2O3, AlCl3, Al2(SO4)3, Al(OH)3 and AlPO4.

25. The method of claim 22, wherein, The lead source is selected from one or more of PbO, Pb3O4, PbO2 and Pb2O3.

26. The method of claim 22, wherein, The cobalt source is selected from one or more of CoO, Co(OH)2, CoCl2 and CoSO4.

27. The method of claim 22, wherein, The calcium source is selected from one or more of CaCl2, CaO, Ca(OH)2 and CaF2.

28. The method of claim 22, wherein, The indium source is selected from one or more of In2O3, In(OH)3 and InCl3.

29. The method of claim 19, wherein, The phosphorus source is selected from one or more of FePO4, AlPO4, Al(PO3)3 and Ca3(PO4)2.

30. The method of claim 19, wherein, The carbon source is carbonized resin and / or graphite.

31. The method of claim 30, wherein, The graphite is amorphous graphite.

32. The method of claim 19, wherein, The temperature of the reaction is 1500-3000℃; the time of the reaction is 12-720 hours.

33. The method of claim 32, wherein, The time of the reaction is 24-120 hours.

34. The method of claim 19, wherein, The volume flow rate of the inert atmosphere is 50-500 mL / min.

35. The method of claim 34, wherein, The volume flow rate of the inert atmosphere is 100-300 mL / min.

36. The method of claim 19, wherein, The length of the chopped carbon fiber is 0.1-10 mm; the specification is 12-320K; the carbon content is 85-95 wt%.

37. The method of claim 36, wherein, The length of the chopped carbon fiber is 1-5 mm.

38. The method of claim 36, wherein, The specification of the chopped carbon fiber is 12-48K.

39. The carbon-carbon composite material with temperature-resistant sealing performance prepared by the method of any one of claims 19-38.

40. The use of the carbon-carbon composite material with temperature-resistant sealing performance of any one of claims 1-18 or the carbon-carbon composite material with temperature-resistant sealing performance of claim 39 as a temperature-resistant sealing material.

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