Carbon material and method for producing the same

Abstract

The present application relates to the technical field of carbon material, and particularly relates to a carbon material and a preparation method thereof. The carbon material comprises a matrix layer, a transition layer and a silicon carbide coating layer, the silicon carbide coating layer partially or entirely coats the matrix layer, the silicon carbide coating layer comprises a nanowire framework, and the transition layer is located between the matrix layer and the silicon carbide coating layer, and the transition layer comprises a metal carbide. The carbon material of the present application improves the bonding force of the interface in the carbon material in a chemical bonding mode, and improves the overall structural stability of the carbon material.

Description

Technical Field

[0001] This invention relates to the field of carbon materials technology, specifically to a carbon material and a method for preparing the carbon material. Background Technology

[0002] Graphite felt products mainly serve as thermal insulation in epitaxial equipment. However, due to the loose and porous nature of graphite felt, it is easily corroded and powdered under the influence of high-temperature corrosive gases during the epitaxial process. These falling particles can contaminate the chamber environment, causing defects on the surface of the epitaxial wafer and reducing the performance of the epitaxial layer.

[0003] To solve this problem, a silicon carbide coating needs to be applied to the surface of the graphite felt to resist the erosion of corrosive gases. However, due to the large difference in the coefficients of thermal expansion between the graphite felt and the silicon carbide coating, a large number of cracks will appear on the surface after coating. Summary of the Invention

[0004] To address the problem of numerous cracks appearing on the surface of silicon carbide coatings due to the significant difference in thermal expansion coefficients between graphite felt and silicon carbide coatings, existing technologies employ a method of pre-building a silicon carbide nanowire framework on the graphite felt surface and then filling the framework with the silicon carbide coating using a CVD process to reduce the risk of coating cracking. However, since the nanowires and the substrate are typically physically bonded, there is still a risk of coating detachment due to insufficient interfacial adhesion, thus reducing the structural stability of the graphite felt product.

[0005] To address the problem of poor overall structural integrity in graphite felt products caused by insufficient interfacial bonding between the nanowire framework and the graphite felt matrix, this invention provides a carbon material and a method for preparing the carbon material. The carbon material of this invention improves the interfacial bonding force through chemical bonding, thereby enhancing the overall structural stability of the carbon material.

[0006] To achieve the above objectives, a first aspect of the present invention provides a carbon material, wherein the carbon material comprises a substrate layer, a transition layer and a silicon carbide coating, the silicon carbide coating being located on one or both sides of the substrate layer, the silicon carbide coating comprising a nanowire framework, the transition layer being located between the substrate layer and the silicon carbide coating, and the transition layer comprising a metal carbide.

[0007] The second aspect of the present invention provides a method for preparing a carbon material, wherein the carbon material prepared by the method is the carbon material described in the first aspect of the present invention.

[0008] By employing the above technical solution, the present invention has at least the following advantages compared with the prior art:

[0009] The carbon material of the present invention includes a transition layer disposed on a substrate layer and a silicon carbide coating. The transition layer is connected to the substrate layer by chemical bonding force, thereby improving the interfacial bonding force between the substrate layer and the transition layer. At the same time, the roots of the nanowires in the nanowire skeleton in the silicon carbide coating (the ends of the nanowires closer to the transition layer) are connected to the metal carbides in the transition layer, thereby enhancing the interfacial bonding force between the transition layer and the silicon carbide coating. This improves the interfacial bonding force of the carbon material and enhances the overall structural stability of the carbon material.

[0010] Other features and advantages of the present invention will be described in detail in the following detailed description section.

[0011] 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. Attached Figure Description

[0012] Figure 1 The diagram shown is a structural schematic of the carbon material of the present invention.

[0013] Figure 2 The image shows the intermediate-state oriented ion arrangement matrix layer in the carbon material preparation process of the present invention.

[0014] Figure 3 The image shows an intermediate state carbon material including a transition layer during the carbon material preparation process of the present invention.

[0015] Figure 4 The image shows an intermediate state of carbon material including a nanowire framework during the preparation process of the carbon material of the present invention. Detailed Implementation

[0016] 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 invention. Unless otherwise specified herein, data ranges include endpoints.

[0017] It should be noted that the numerical designations such as "first" and "second" in this invention are only used to distinguish different substances or methods of use, and do not represent a difference in order.

[0018] The first aspect of the present invention provides a carbon material, wherein the carbon material includes a substrate layer, a transition layer and a silicon carbide coating, the silicon carbide coating is located on one or both sides of the substrate layer, the silicon carbide coating includes a nanowire framework, the transition layer is located between the substrate layer and the silicon carbide coating, and the transition layer includes a metal carbide.

[0019] like Figure 1 As shown, the carbon material 1 includes a substrate layer 11, a transition layer 12, and a silicon carbide coating 13. The silicon carbide coating 13 is located on one or both sides of the substrate layer 11, and the transition layer 12 is located between the substrate layer 11 and the silicon carbide coating 13. The transition layer 12 includes a metal carbide 122.

[0020] The carbon material of the present invention includes a transition layer located between a substrate layer and a silicon carbide coating. The transition layer includes a metal carbide, which is formed by a chemical reaction between carbon elements in the substrate layer and carbon elements provided by a carbon source gas and metal ions. Therefore, the substrate layer and the transition layer are bonded by atomic-level chemical forces, resulting in strong interfacial bonding between the substrate layer and the transition layer. At the same time, the roots of the nanowires in the nanowire framework of the silicon carbide coating are connected to the metal carbide in the transition layer, giving the transition layer and the silicon carbide coating a strong interfacial bonding force. This improves the interfacial bonding force of the carbon material and enhances the overall structural stability of the carbon material.

[0021] In this invention, a transition layer is provided between the substrate layer and the silicon carbide coating to improve the interfacial adhesion of the carbon material. Compared with the prior art, this improves the interfacial adhesion of the carbon material and enhances its overall structural stability. To further improve the effect, one or more of the technical features can be further optimized.

[0022] In one example, the nanowire framework comprises a plurality of (>1) nanowires with an aspect ratio of 20-100 (e.g., 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100). Controlling the aspect ratio of the nanowires within this range allows them to intertwine or overlap, forming a network structure with good continuity, thereby self-assembling into a self-supporting membrane with certain mechanical properties. When the aspect ratio of the nanowires is higher than 100, the excessive aspect ratio can easily lead to excessive bending or even collapse and entanglement; when the aspect ratio of the nanowires is lower than 20, the aspect ratio is not conducive to further effectively anchoring and covering the silicon carbide coating.

[0023] In one example, the aspect ratio of the nanowire is 40-70.

[0024] In this invention, the aspect ratio of the nanowires can be obtained by SEM or OM testing.

[0025] In one example, the length of the nanowire is 10 μm to 30 μm (e.g., 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, 28 μm or 30 μm).

[0026] According to one specific embodiment, the aspect ratio of the nanowire is 20-100, and the length of the nanowire is 10μm-30μm.

[0027] According to one specific embodiment, the aspect ratio of the nanowire is 40-70, and the length of the nanowire is 10μm-30μm.

[0028] In one example, the angle between the nanowire and the silicon carbide coating is 30°-70° (e.g., 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, or 70°). Controlling the angle between the nanowire and the silicon carbide coating within this range enhances the mechanical anchoring effect. The tilted nanowire increases the contact area between the silicon carbide coating and the nanowire, strengthens chemical bonding and van der Waals forces, converts the shear stress borne by the silicon carbide coating into compressive stress, reduces the tendency for interfacial delamination, and reduces the tensile stress perpendicular to the interface caused by thermal expansion mismatch. This improves the adhesion between the silicon carbide coating and the transition layer, reducing the risk of silicon carbide coating detachment.

[0029] In one example, the angle between the nanowire and the silicon carbide coating is 45°-60°.

[0030] In one example, the nanowires are composed of silicon carbide, that is, the nanowires are silicon carbide nanowires.

[0031] In one example, the root of the nanowire is the metal carbide. In this invention, the root of the nanowire refers to the end of the nanowire near the transition layer.

[0032] In one example, the silicon carbide coating comprises a carbon-rich layer, a medium-carbon layer, and a low-carbon layer. It is understood that the silicon carbide coating comprises carbon and silicon, the carbon-rich layer comprises carbon and silicon, the medium-carbon layer comprises carbon and silicon, and the low-carbon layer comprises carbon and silicon.

[0033] In one example, the carbon-rich layer is located on the side closer to the substrate layer, the low-carbon layer is located on the side farther from the substrate layer, and the medium-carbon layer is located between the carbon-rich layer and the low-carbon layer.

[0034] It is understood that the weight ratio of carbon to silicon in the carbon-rich layer is greater than that in the medium-carbon layer, which is greater than that in the low-carbon layer. The silicon carbide coating includes a first surface and a second surface, with the first surface close to the transition layer and the second surface far from the transition layer. Therefore, in the thickness direction of the carbon material, the weight ratio of carbon to silicon decreases from the first surface to the second surface.

[0035] In one example, the molar ratio of carbon to silicon in the carbon-rich layer is (2-3):1 (e.g., 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, or 3:1), and the molar ratio of carbon to silicon in the medium-carbon layer is (0.9-1.1):1 (e.g., 0.9:1 ... 93:1, 0.95:1, 0.98:1, 1:1, 1.03:1, 0.05:1, 1.08:1 or 1.1:1), wherein the molar ratio of carbon to silicon in the low-carbon layer is 1:(2-3) (e.g., 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3).

[0036] By controlling the molar ratio of carbon to silicon in the carbon-rich layer, the molar ratio of carbon to silicon in the medium-carbon layer, and the molar ratio of carbon to silicon in the low-carbon layer to be within the aforementioned ranges, the thermal expansion coefficient of the silicon carbide coating and the expansion coefficient between the silicon carbide coating and the transition layer can be kept relatively small, thereby further reducing the risk of cracking in the silicon carbide coating and improving the structural consistency of the carbon material.

[0037] In one example, the thickness of the carbon-rich layer is 5 μm-10 μm (e.g., 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm). In this invention, the thickness of the carbon-rich layer can be obtained by SEM or OM testing.

[0038] According to one specific embodiment, the weight ratio of carbon to silicon in the carbon-rich layer is (2-3):1, and the thickness of the carbon-rich layer is 5μm-10μm.

[0039] In one example, the thickness of the intermediate carbon layer is 20 μm-50 μm (e.g., 20 μm, 23 μm, 25 μm, 28 μm, 30 μm, 33 μm, 35 μm, 38 μm, 40 μm, 43 μm, 45 μm, 48 μm, or 50 μm). In this invention, the thickness of the intermediate carbon layer can be obtained by SEM or OM testing.

[0040] According to one specific embodiment, the weight ratio of carbon to silicon in the intermediate carbon layer is (0.9-1.1):1, and the thickness of the intermediate carbon layer is 20μm-50μm.

[0041] In one example, the thickness of the low-carbon layer is 5 μm-10 μm (e.g., 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm). In this invention, the thickness of the low-carbon layer can be obtained by SEM or OM testing.

[0042] According to one specific embodiment, the weight ratio of carbon to silicon in the low-carbon layer is 1:(2-3), and the thickness of the low-carbon layer is 5μm-10μm.

[0043] According to one specific embodiment, the weight ratio of carbon to silicon in the carbon-rich layer is (2-3):1, the weight ratio of carbon to silicon in the medium-carbon layer is (0.9-1.1):1, the weight ratio of carbon to silicon in the low-carbon layer is 1:(2-3), the thickness of the carbon-rich layer is 5μm-10μm, the thickness of the medium-carbon layer is 20μm-50μm, and the thickness of the medium-carbon layer is 5μm-10μm.

[0044] In one example, the metal carbide includes one or more of titanium carbide, zirconium carbide, chromium carbide, tantalum carbide, niobium carbide, molybdenum carbide, zirconium carbide, and tungsten carbide.

[0045] In one example, the metal carbide includes tantalum carbide and / or niobium carbide.

[0046] In one example, the concentration of the metal carbide in the transition layer varies in a gradient, with the concentration of the metal carbide in the transition layer closer to the substrate layer being greater than the concentration of the metal carbide in the transition layer farther from the substrate layer.

[0047] In this invention, the concentration of the metal carbide in the transition layer refers to the atomic percentage (at.%) of the metal element in a specific region of the transition layer (e.g., near the substrate side, far from the substrate side) (i.e., the percentage of the number of metal atoms in that region relative to the total number of atoms).

[0048] In one example, the concentration of the metal carbide in the transition layer on the side near the substrate layer is 35 at% to 65 at%.

[0049] In one example, the concentration of the metal carbide in the transition layer on the side away from the substrate layer is 8 at% to 35 at%.

[0050] According to one specific embodiment, the concentration of the metal carbide in the transition layer on the side closer to the substrate layer is greater than the concentration of the metal carbide in the transition layer on the side farther from the substrate layer. The concentration of the metal carbide in the transition layer on the side closer to the substrate layer is 35at%-65at, and the concentration of the metal carbide in the transition layer on the side farther from the substrate layer is 8at%-35at.

[0051] In one example, the thickness of the transition layer is 10 μm-30 μm (e.g., 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, 28 μm or 30 μm).

[0052] In one example, the thickness of the substrate layer is 1mm-50mm (e.g., 1mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm or 50mm).

[0053] In one example, the matrix layer comprises one or more of bituminous graphite felt, polyacrylonitrile-based graphite felt, and adhesive-based graphite felt.

[0054] In one example, the carbon content in the substrate layer is ≥99% by weight (e.g., 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, or 100%).

[0055] The substrate layer can be obtained by treating carbon felt at a high temperature of over 2000°C under vacuum or inert gas.

[0056] The second aspect of the present invention provides a method for preparing a carbon material, wherein the carbon material prepared by the method is the carbon material described in the first aspect of the present invention.

[0057] In one instance, the method includes:

[0058] a) Ion implantation: Ion implantation is performed on the substrate layer to obtain an ionized substrate layer;

[0059] b) Magnetic field annealing: In an inert atmosphere, a magnetic field is applied to the ionized matrix layer to perform magnetic field annealing to obtain a matrix layer with oriented ion arrangement;

[0060] c) Pre-carbonization treatment: The oriented ion-distributed matrix layer comes into first contact with the first carbon source and the first hydrogen gas to obtain a carbon material including a transition layer (e.g., Figure 3 );

[0061] d) Nanowire framework: The carbon material including the transition layer is brought into a second contact with the second carbon source and the first silicon source to obtain a carbon material including a nanowire framework;

[0062] e) Silicon carbide coating: The carbon material including the nanowire framework makes a third contact, a fourth contact, and a fifth contact with a third carbon source, a second silicon source, a second hydrogen gas, and an argon gas, respectively.

[0063] To grow silicon carbide nanowires on a substrate surface, the substrate needs to be treated to obtain catalytic sites (metal catalysts or particles) to induce silicon carbide growth. A common method is to deposit metal catalysts such as iron, nickel, or cobalt on the substrate surface using chemical vapor deposition (CVD). These metals act as catalysts, promoting the decomposition and deposition of carbon source gases (such as methane or ethylene) at high temperatures to form silicon carbide nanowires. However, while introducing metal catalysts onto the graphite felt via CVD, metal ions also adhere to other locations within the furnace, potentially leading to excessive metal ion levels on the coating surface when using the same deposition furnace to produce normal silicon carbide coatings. Alternatively, physical methods such as sputtering can be used to introduce metal particles onto the substrate surface to form catalytic sites. These metal particles can also play a similar role, promoting the decomposition and reaction of carbon source gases. However, physical sputtering carries a higher risk of damaging the substrate layer due to the risk of high-energy particle impacts that can damage or alter its structure.

[0064] This invention modifies the surface of a substrate layer through ion implantation to obtain catalytic sites for growing silicon carbide nanowires. It allows for very precise control of doping concentration and depth, is independent of temperature-driven or diffusion processes, and alters only the surface of the material without affecting its bulk properties. Figure 2 As shown, metal ions 121 are implanted on the surface of the substrate layer.

[0065] In one example, the ion implantation conditions include an energy of 10 × 10⁻⁶. 3 eV-70×10 3 eV (e.g., 10×10) 3 eV, 15×10 3 eV, 20×10 3 eV, 25×10 3 eV, 30×10 3 eV, 35×10 3 eV, 40×10 3 eV, 45×10 3eV, 50×10 3 eV, 55×10 3 eV, 60×10 3 eV, 65×10 3 eV or 70×10 3 eV), the dose is 1 ions / cm 2 -7×10 16 ions / cm 2 (e.g., 1ions / cm 2 、50ions / cm 2 、100ions / cm 2 、500ions / cm 2 、1000ions / cm 2 、5000ions / cm 2 、10000ions / cm 2 、50000ions / cm 2 、1×10 6 ions / cm 2 、5×10 6 ions / cm 2 、1×10 7 ions / cm 2 、5×10 7 ions / cm 2 、1×10 8 ions / cm 2 、5×10 8 ions / cm 2 、1×10 9 ions / cm 2 、5×10 9 ions / cm 2 、1×10 10 ions / cm 2 、5×10 10 ions / cm 2 、1×10 11 ions / cm 2 、5×10 11 ions / cm 2 、1×10 12 ions / cm 2 、5×10 12 ions / cm 2 、1×10 13 ions / cm 2 、5×10 13 ions / cm 2 、1×10 14ions / cm 2 5×10 14 ions / cm 2 1×10 15 ions / cm 2 5×10 15 ions / cm 2 Or 1×10 16 ions / cm 2 The injection angle is 5°-10° (e.g., 5°, 6°, 7°, 8°, 9° or 10°).

[0066] In one example, the ion source for ion implantation includes one or more of the following: iron ions (+2, +3 valence), cobalt ions (+2 valence), nickel ions (+2 valence), tantalum ions (+4 valence), and niobium ions (+4 valence).

[0067] In one example, the depth of ions in the ionized matrix layer is 10nm-200nm (e.g., 10nm, 30nm, 50nm, 80nm, 100nm, 130nm, 150nm, 180nm or 200nm).

[0068] In one example, the concentration of ions on the surface of the ionized substrate layer is 5 at.% to 15 at.% (e.g., 5 at.%, 6 at.%, 7 at.%, 8 at.%, 9 at.%, 10 at.%, 11 at.%, 12 at.%, 13 at.%, 14 at.% or 15 at.%).

[0069] In this invention, the concentration of ions on the surface of the ionized substrate layer refers to the molar ratio of metal elements to carbon elements on the surface of the ionized substrate layer.

[0070] In one example, the conditions for magnetic field annealing include: a temperature of 900°C-1650°C (e.g., 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C, 1600°C, or 1650°C), a magnetic field strength of 2.5T-3.5T (e.g., 2.5T, 2.8T, 3T, 3.3T, or 3.5T), and a time of 2h-4h (e.g., 2h, 2.3h, 2.5h, 2.8h, 3h, 3.3h, 3.5h, 3.8h, or 4h). After the ionized substrate layer is annealed in a magnetic field, the ions implanted in the substrate layer can achieve directional arrangement. At the same time, the metal ions and the C element in the substrate form directional gradient metal carbides. The directional metal carbides are conducive to the formation of regularly arranged nanowires, thereby forming a better network structure. This allows for the self-assembly of a self-supporting film with certain mechanical properties, thus improving the structural stability of the silicon carbide coating.

[0071] In one example, the first carbon source includes one or more of methane, ethane, propane, ethylene, propylene, acetylene, toluene, trichloromethylsilane (Cl3SiCH3), dimethyldichlorosilane ((CH3)2SiCl2), carbon tetrachloride (CCl4), chloroform (CHCl3), dichloromethane (CH2Cl2), and chloromethane (CH3Cl).

[0072] In one example, the first carbon source includes one or more of methane, trichloromethylsilane (Cl3SiCH3), and ethylene.

[0073] In one example, the conditions for the first contact include: a temperature of 800°C-1100°C (e.g., 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, or 1100°C), a pressure of 200Pa-1000Pa (e.g., 200Pa, 300Pa, 400Pa, 500Pa, 600Pa, 700Pa, 800Pa, 900Pa, or 1000Pa), and a time of 5min-10min (e.g., 5min, 6min, 7min, 8min, 9min, or 10min).

[0074] In one example, the first carbon source is introduced in a pulsed manner for the first contact, wherein the pulse conditions are: the introduction time is 10s-60s (e.g., 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s or 60s), and the interruption time is 3s-10s (e.g., 3s, 4s, 5s, 6s, 7s, 8s, 9s or 10s).

[0075] In one instance, the first hydrogen gas is introduced continuously for the first contact.

[0076] In one example, the flow rate of the first carbon source is 2 L / min to 12 L / min (e.g., 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, 11 L / min or 12 L / min).

[0077] In one example, the flow rate of the first hydrogen gas is 12 L / min to 120 L / min (e.g., 12 L / min, 20 L / min, 30 L / min, 40 L / min, 50 L / min, 60 L / min, 70 L / min, 80 L / min, 90 L / min, 100 L / min, 110 L / min or 120 L / min).

[0078] In one example, the oriented ion-distributed substrate layer comes into first contact with a first carbon source and a first hydrogen gas, and a chemical reaction occurs to form a transition layer comprising a metal carbide. This allows the substrate layer and the transition layer to be bonded by atomic-level chemical forces, improving interfacial adhesion. It is understood that the metal ions forming the metal carbide are metal ions implanted into the substrate layer, and the carbon forming the metal carbide is provided by the first carbon source and the carbon in the substrate layer.

[0079] In one example, the second carbon source includes one or more of methane, ethane, propane, ethylene, propylene, acetylene, toluene, trichloromethylsilane (Cl3SiCH3), dimethyldichlorosilane ((CH3)2SiCl2), carbon tetrachloride (CCl4), chloroform (CHCl3), dichloromethane (CH2Cl2), and chloromethane (CH3Cl).

[0080] In one example, the second carbon source includes one or more of methane, trichloromethylsilane (Cl3SiCH3), and ethylene.

[0081] In one example, the first silicon source includes one or more of methylsilane, ethylsilane, propylsilane, butylsilane, dichloromethylsilane, silicon tetrachloride, and trichloromethylsilane.

[0082] In one example, the first silicon source includes one or more of methylsilane, ethylsilane, propylsilane, butylsilane, and trichloromethylsilane.

[0083] In one example, the conditions for the second contact include: a temperature of 800°C-1100°C (e.g., 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, or 1100°C), a pressure of 500Pa-1500Pa (e.g., 500Pa, 600Pa, 700Pa, 800Pa, 900Pa, 1000Pa, 1100Pa, 1200Pa, 1300Pa, 1400Pa, or 1500Pa), and a time of 2h-5h (e.g., 2h, 2.3h, 2.5h, 3h, 3.3h, 3.5h, 3.8h, 4h, 4.3h, 4.5h, 4.8h, or 5h).

[0084] In one example, the flow rate of the second carbon source is 2 L / min to 12 L / min (e.g., 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, 11 L / min or 12 L / min).

[0085] In one example, the flow rate of the first silicon source is 60 L / min to 120 L / min (e.g., 60 L / min, 65 L / min, 70 L / min, 75 L / min, 80 L / min, 85 L / min, 90 L / min, 95 L / min, 100 L / min, 105 L / min, 110 L / min, 115 L / min or 120 L / min).

[0086] In one example, the carbon material including the transition layer makes a second contact with the second carbon source and the first silicon source. At this point, the metal carbides in the transition layer act as reactive sites, generating silicon carbide nanowires and thus constructing a nanowire framework. Furthermore, due to the directional arrangement of metal ions forming the metal silicon carbide, the silicon carbide nanowires formed with metal carbides as reactive sites also possess directional arrangement characteristics. The nanowire framework formed by the directionally arranged silicon carbide nanowires has a better network structure, which can improve the supporting effect and thus enhance the structural stability of the silicon carbide coating.

[0087] like Figure 4 As shown, silicon carbide nanowires formed with metal carbides as reactive sites have metal carbides 122 at the root of silicon carbide nanowires 131.

[0088] In one example, the conditions for the third contact include: a temperature of 800°C-1200°C (e.g., 800°C, 900°C, 1000°C, 1100°C, or 1200°C), a pressure of 3000Pa-5000Pa (e.g., 3000Pa, 3300Pa, 3500Pa, 3800Pa, 4000Pa, 4300Pa, 4500Pa, 4800Pa, or 5000Pa), a time of 0.5h-1.5h, a flow rate of 50L / min-100L / min for the third carbon source, a flow rate of 50L / min-100L / min for the second silicon source, a flow rate of 800L / min-1200L / min for the second hydrogen, and a flow rate of 200L / min-500L / min for the argon, forming a carbon-rich layer with a thickness of 5μm-10μm.

[0089] The third contact can fill the nanowire framework to form a carbon-rich layer. Moreover, by controlling the flow rate of the third carbon source and the second silicon source, the weight ratio of carbon to silicon in the carbon-rich layer can be made to be (2-3):1.

[0090] In one example, the conditions for the fourth contact include: a temperature of 1200℃-1400℃, a pressure of 1000Pa-3000Pa (e.g., 1000Pa, 1300Pa, 1500Pa, 1800Pa, 2000Pa, 2300Pa, 2500Pa, 2800Pa or 3000Pa), a time of 2h-3h, a flow rate of 150L / min-250L / min for the third carbon source, a flow rate of 150L / min-250L / min for the second silicon source, a flow rate of 2000L / min-4000L / min for the second hydrogen, and the formation of a medium carbon layer with a thickness of 20μm-50μm.

[0091] The fourth contact can fill the nanowire framework to form a medium carbon layer. Moreover, by controlling the flow rates of the third carbon source and the second silicon source, the weight ratio of carbon to silicon in the medium carbon layer can be made to be (0.9-1.1):1.

[0092] In one example, the conditions for the fifth contact include: a temperature of 1300℃-1500℃, a pressure of 12000Pa-15000Pa, a time of 1h-1.5h, a flow rate of 60L / min-100L / min for the third carbon source, a flow rate of 60L / min-100L / min for the second silicon source, a flow rate of 200L / min-500L / min for the second hydrogen gas, and a flow rate of 1500L / min-3000L / min for the argon gas, forming a low-carbon layer with a thickness of 5μm-10μm.

[0093] The fifth contact can fill the nanowire framework to form a low-carbon layer. Moreover, by controlling the flow rate of the third carbon source and the second silicon source, the weight ratio of carbon to silicon in the low-carbon layer can be made to be 1:(1.2-1.5).

[0094] A silicon carbide coating can be formed by filling the nanowire skeleton through the third, fourth, and fifth contacts. The silicon carbide coating has high hardness, high melting point, and excellent chemical stability, which can effectively protect the substrate surface from corrosion and wear.

[0095] The present invention will be described in detail below through embodiments. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0096] The following examples illustrate the carbon material of the present invention.

[0097] Example 1

[0098] Preparation of carbon materials:

[0099] a) Ion implantation: Ion implantation is performed on the substrate layer (polyacrylonitrile-based graphite felt) to obtain an ionized substrate layer (wherein, the ion source is tantalum ions, and the depth of the ions in the ionized substrate layer is 100 nm).

[0100] b) Magnetic field annealing: In an inert atmosphere, a magnetic field is applied to the ionized matrix layer to perform magnetic field annealing to obtain a matrix layer with oriented ion arrangement;

[0101] c) Pre-carbonization treatment: The directional ion-distributed matrix layer is brought into first contact with the first carbon source (methane, flow rate of 6 L / min) and the first hydrogen gas (flow rate of 60 L / min) to obtain a carbon material including a transition layer.

[0102] d) Nanowire framework: The carbon material including the transition layer is brought into a second contact with a second carbon source (methane, flow rate of 6 L / min) and a first silicon source (methylsilane, flow rate of 90 L / min) to obtain a carbon material including a nanowire framework; wherein the length of the nanowire is 20.14 μm and the aspect ratio of the nanowire is 50.11.

[0103] e) Silicon carbide coating: The carbon material including the nanowire framework makes a third contact, a fourth contact, and a fifth contact with a third carbon source (methane, flow rate of 80 L / min), a second silicon source (methylsilane, flow rate of 80 L / min), a second hydrogen gas, and an argon gas, respectively; wherein the included angle between the nanowire and the silicon carbide coating is 50.5°.

[0104] The conditions for ion implantation include: an energy of 40 × 10⁻⁶. 3 eV, dose 4×10 16 ions / cm 2 The injection angle is 8°; the ion depth in the ionized matrix layer is 100 nm; the magnetic field annealing conditions include: temperature 1200℃, magnetic field strength 3T, and time 3h; the first contact conditions include: temperature 950℃, pressure 600Pa, and time 8min; the first carbon source is introduced in a pulsed manner for the first contact, wherein the pulse conditions are: introduction time 30s, interruption time 6s; the first hydrogen gas is introduced continuously for the first contact; the second contact conditions include: temperature 950℃, pressure 1000Pa, and time 3.5h;

[0105] The conditions for the third contact include: a temperature of 1000℃, a pressure of 4000Pa, a time of 1h, a flow rate of 80L / min for the third carbon source, a flow rate of 80L / min for the second silicon source, a flow rate of 1000L / min for the second hydrogen gas, and a flow rate of 350L / min for the argon gas; the thickness of the carbon-rich layer formed by filling the nanowire framework in the third contact is 7.2μm, and the molar ratio of carbon to silicon in the carbon-rich layer is 2.6:1;

[0106] The conditions for the fourth contact include: a temperature of 1300℃, a pressure of 2000Pa, a time of 2.5h, a flow rate of 200L / min for the third carbon source, a flow rate of 200L / min for the second silicon source, and a flow rate of 3000L / min for the second hydrogen gas; the thickness of the intermediate carbon layer formed in the nanowire framework in the fourth contact is 40μm, and the molar ratio of carbon to silicon in the intermediate carbon layer is 1:1;

[0107] The conditions for the fifth contact include: a temperature of 1400℃, a pressure of 13500Pa, a time of 1.2h, a flow rate of 80L / min for the third carbon source, a flow rate of 80L / min for the second silicon source, a flow rate of 350L / min for the second hydrogen gas, and a flow rate of 2250L / min for the argon gas; the thickness of the low-carbon layer formed by filling the nanowire framework in the fifth contact is 7.5μm, and the molar ratio of carbon to silicon in the low-carbon layer is 1:2.4;

[0108] The concentration of tantalum carbide in the transition layer varies in a gradient, with the concentration of tantalum carbide in the transition layer being greater on the side closer to the polyacrylonitrile-based graphite felt than on the side farther away from the polyacrylonitrile-based graphite felt.

[0109] Example 2 group

[0110] This set of examples is used to verify the effects of changes in the length and aspect ratio of the nanowires.

[0111] This set of embodiments is based on Embodiment 1, except that the length and aspect ratio of the nanowires are changed.

[0112] Example 2a: The length of the nanowire is 10.11 μm.

[0113] Example 2b: The length of the nanowire is 29.95 μm.

[0114] Example 2c: The aspect ratio of the nanowire is 30.28.

[0115] In Example 2d, the aspect ratio of the nanowires was 40.19.

[0116] Example 2e: The aspect ratio of the nanowire is 60.88.

[0117] Example 2f: The aspect ratio of the nanowire is 69.92.

[0118] Example 2g, the aspect ratio of the nanowires is 98.64.

[0119] Example 3 Group

[0120] This set of examples is used to verify the effect of changing the angle between the nanowire and the silicon carbide coating.

[0121] This set of embodiments is based on Embodiment 1, except that the angle between the nanowires and the silicon carbide coating is changed.

[0122] In Example 3a, the angle between the nanowire and the silicon carbide coating is 30.2°.

[0123] In Example 3b, the angle between the nanowires and the silicon carbide coating is 45.9°.

[0124] In Example 3c, the angle between the nanowire and the silicon carbide coating is 59.1°.

[0125] In Example 3d, the angle between the nanowires and the silicon carbide coating was 69.8°.

[0126] In Example 3d, the angle between the nanowire and the silicon carbide coating was 90°.

[0127] Example 4 group

[0128] This set of examples is used to verify the impact of changing the molar ratio of carbon to silicon in the carbon-rich layer, medium-carbon layer, and low-carbon layer.

[0129] This set of embodiments is based on Embodiment 1, except that the molar ratio of carbon to silicon in the carbon-rich layer, medium-carbon layer and low-carbon layer is changed.

[0130] In Example 4a, the molar ratio of carbon to silicon in the carbon-rich layer is 3:1, and the molar ratio of carbon to silicon in the low-carbon layer is 1:2.

[0131] In Example 4b, the molar ratio of carbon to silicon in the carbon-rich layer is 2:1, the molar ratio of carbon to silicon in the medium-carbon layer is 1.1:1, and the molar ratio of carbon to silicon in the low-carbon layer is 1:2.

[0132] In Example 4c, the molar ratio of carbon to silicon in the carbon-rich layer is 2:1, the molar ratio of carbon to silicon in the medium-carbon layer is 2:1, and the molar ratio of carbon to silicon in the low-carbon layer is 1:3.

[0133] Example 5

[0134] This embodiment is used to verify the impact of changes in the concentration of metal carbides in the transition layer.

[0135] This embodiment is based on Example 1, except that the concentration of tantalum carbide in the transition layer does not change gradient. The concentration of tantalum carbide in the transition layer on the side closer to the polyacrylonitrile-based graphite felt is equal to the concentration of tantalum carbide in the transition layer on the side farther from the polyacrylonitrile-based graphite felt.

[0136] Comparative Example 1

[0137] The procedure was carried out in accordance with Example 1, except that steps a) to c) were omitted, and the polyacrylonitrile-based graphite felt surface had no transition layer.

[0138] Comparative Example 2

[0139] The procedure was carried out in accordance with Example 1, except that step d) was omitted, and the surface of the polyacrylonitrile-based graphite felt had no nanowire framework.

[0140] Comparative Example 3

[0141] The procedure was carried out in accordance with Example 1, except that steps a) to d) were omitted, and the polyacrylonitrile-based graphite felt surface had no transition layer and nanowire skeleton, directly forming a silicon carbide coating.

[0142] Comparative Example 4

[0143] The procedure was carried out in accordance with Example 1, except that step c) was omitted. The surface of the polyacrylonitrile-based graphite felt has no transition layer and only metal ions are present. The roots of the silicon carbide nanowires are metal ions.

[0144] Test case

[0145] (1) Thermal shock test

[0146] The carbon materials prepared in the examples and comparative examples were subjected to thermal shock tests. The specific test methods are as follows:

[0147] The prepared carbon material was cut into test samples of Φ200mm×5mm (i.e., diameter 200mm, thickness 5mm). Thermal shock testing was performed using an HWL-14RZ thermal shock furnace. Starting from room temperature, the temperature was increased to 550℃ at a rate of 8℃ / min and held at this target temperature for 60min. After holding, the sample was removed and placed in a 500mm×500mm×300mm water bath for water cooling. After 20s, the sample was removed, and the surface was observed for any abnormalities such as cracks or peeling of the silicon carbide coating. If no such abnormalities were observed, the sample was placed back into the thermal shock furnace for the next round of thermal shock testing, repeating the "heating-holding-cooling" procedure. If any abnormalities were observed in the silicon carbide coating after a certain round of testing, the experiment was terminated, and the cumulative number of thermal shock cycles completed from the start to the end of the experiment (i.e., the final effective number of thermal shock cycles) was recorded. The results are shown in Table 1.

[0148] (2) Bonding strength test

[0149] The carbon materials prepared in the examples and comparative examples were subjected to bonding strength tests, and the specific test methods are as follows:

[0150] The prepared carbon material was cut into strips of 8mm × 15mm × 30mm. The strips were then bonded together in a cross-hatching pattern, with the 15mm × 30mm side of the sample used as the bonding surface. After bonding, the samples were left to stand for 12 hours to allow the adhesive to solidify. The cross-hatched samples were then mounted on a universal testing machine. The width and thickness of the sample were input, the test loading speed was set to 0.5mm / min, and the test was started. After the test, the fracture load B (in N) and the sample bonding area C (in mm²) were recorded. 2 Then, the interfacial bonding force A (in MPa) is calculated according to the formula A=B / C, and the results are recorded in Table 1.

[0151] Table 1

[0152]

[0153] As can be seen from Table 1, the carbon material prepared by the method of the present invention has a higher number of thermal shock cycles compared with the comparative example, which significantly improves the interfacial bonding force and overall structural stability of the carbon material.

[0154] 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 material, characterized in that, The carbon material includes a substrate layer, a transition layer, and a silicon carbide coating. The silicon carbide coating partially or completely covers the substrate layer. The silicon carbide coating includes a nanowire framework, which is a silicon carbide nanowire framework. The transition layer is located between the substrate layer and the silicon carbide coating. The transition layer includes a metal carbide. The nanowire framework includes a plurality of nanowires, which are silicon carbide nanowires. One end of each nanowire near the transition layer is connected to the metal carbide in the transition layer.

2. The carbon material according to claim 1, wherein, The silicon carbide coating comprises a carbon-rich layer, a medium-carbon layer, and a low-carbon layer. The molar ratio of carbon to silicon in the carbon-rich layer is (2-3):1, the molar ratio of carbon to silicon in the medium-carbon layer is (0.9-1.1):1, and the molar ratio of carbon to silicon in the low-carbon layer is 1:(2-3). The carbon-rich layer is located on the side closer to the substrate layer, the low-carbon layer is located on the side farther from the substrate layer, and the medium-carbon layer is located between the carbon-rich layer and the low-carbon layer. And / or, the aspect ratio of the nanowire is 20-100.

3. The carbon material according to claim 2, wherein, The thickness of the carbon-rich layer is 5μm-10μm; And / or, the thickness of the intermediate carbon layer is 20μm-50μm; And / or, the thickness of the low-carbon layer is 5μm-10μm; And / or, the nanowires are composed of silicon carbide; And / or, the angle between the nanowire and the silicon carbide coating is 30°-70°; And / or, the length of the nanowire is 10 μm-30 μm.

4. The carbon material according to any one of claims 1-3, wherein, The metal carbides include one or more of titanium carbide, zirconium carbide, chromium carbide, tantalum carbide, niobium carbide, molybdenum carbide, zirconium carbide, and tungsten carbide; And / or, the concentration of the metal carbide in the transition layer varies in a gradient, with the concentration of the metal carbide in the transition layer on the side closer to the substrate layer being greater than the concentration of the metal carbide in the transition layer on the side farther from the substrate layer; And / or, the thickness of the transition layer is 10μm-30μm; And / or, the thickness of the substrate layer is 1mm-50mm; And / or, the matrix layer includes one or more of bituminous graphite felt, polyacrylonitrile-based graphite felt, and adhesive-based graphite felt.

5. A method for preparing a carbon material, characterized in that, The carbon material prepared by the method is the carbon material according to any one of claims 1-4.

6. The method according to claim 5, wherein, The method includes: a) Ion implantation: Ion implantation is performed on the substrate layer to obtain an ionized substrate layer; b) Magnetic field annealing: In an inert atmosphere, a magnetic field is applied to the ionized matrix layer to perform magnetic field annealing to obtain a matrix layer with oriented ion arrangement; c) Pre-carbonization treatment: The directional ion-distributed matrix layer is brought into first contact with the first carbon source and the first hydrogen gas to obtain a carbon material including a transition layer; d) Nanowire framework: The carbon material including the transition layer is brought into a second contact with the second carbon source and the first silicon source to obtain a carbon material including a nanowire framework; e) Silicon carbide coating: The carbon material including the nanowire framework makes a third contact, a fourth contact, and a fifth contact with a third carbon source, a second silicon source, a second hydrogen gas, and an argon gas, respectively.

7. The method according to claim 6, wherein, The conditions for ion implantation include: an energy of 10 × 10⁻⁶. 3 eV-70×10 3 eV, dose of 1 ions / cm 2 -7×10 16 ions / cm 2 The injection angle is 5°-10°; And / or, the ion source for ion implantation includes one or more of iron ions, cobalt ions, nickel ions, tantalum ions, and niobium ions; And / or, the depth of ions in the ionized matrix layer is 10nm-200nm; And / or, the concentration of ions on the surface of the ionized substrate layer is 5-15 at.%.

8. The method according to claim 6, wherein, The conditions for magnetic field annealing include: a temperature of 900℃-1650℃, a magnetic field strength of 2.5T-3.5T, and a time of 2h-4h. And / or, the first carbon source includes one or more of methane, ethane, propane, ethylene, propylene, acetylene, toluene, trichloromethylsilane, dimethyldichlorosilane, carbon tetrachloride, trichloromethane, dichloromethane, and chloromethane; And / or, the conditions for the first contact include: a temperature of 800℃-1100℃, a pressure of 200Pa-1000Pa, and a time of 5min-10min; And / or, the first carbon source is introduced in a pulsed manner for the first contact, wherein the pulse conditions are: the introduction time is 10s-60s and the interruption time is 3s-10s; And / or, the first hydrogen gas is introduced continuously for the first contact; And / or, the flow rate of the first carbon source is 2 L / min-12 L / min; And / or, the flow rate of the first hydrogen gas is 12 L / min to 120 L / min.

9. The method according to claim 6, wherein, The second carbon source includes one or more of ethane, propane, ethylene, propylene, acetylene, toluene, trichloromethylsilane, dimethyldichlorosilane, carbon tetrachloride, trichloromethane, dichloromethane, and chloromethane; And / or, the first silicon source includes one or more of methylsilane, ethylsilane, propylsilane, butylsilane, dichloromethylsilane, silicon tetrachloride, and trichloromethylsilane; And / or, the conditions for the second contact include: a temperature of 800℃-1100℃, a pressure of 500Pa-1500Pa, and a time of 2h-5h; And / or, the flow rate of the second carbon source is 2 L / min-12 L / min; And / or, the flow rate of the first silicon source is 60L / min-120L / min.

10. The method according to any one of claims 6-9, wherein, The conditions for the third contact include: a temperature of 800℃-1200℃, a pressure of 3000Pa-5000Pa, a time of 0.5h-1.5h, a flow rate of 50L / min-100L / min for the third carbon source, a flow rate of 50L / min-100L / min for the second silicon source, a flow rate of 800L / min-1200L / min for the second hydrogen gas, and a flow rate of 200L / min-500L / min for the argon gas. And / or, the conditions for the fourth contact include: a temperature of 1200℃-1400℃, a pressure of 1000Pa-3000Pa, a time of 2h-3h, a flow rate of 150L / min-250L / min for the third carbon source, a flow rate of 150L / min-250L / min for the second silicon source, and a flow rate of 2000L / min-4000L / min for the second hydrogen gas; And / or, the conditions for the fifth contact include: a temperature of 1300℃-1500℃, a pressure of 12000Pa-15000Pa, a time of 1h-1.5h, a flow rate of 60L / min-100L / min for the third carbon source, a flow rate of 60L / min-100L / min for the second silicon source, a flow rate of 200L / min-500L / min for the second hydrogen gas, and a flow rate of 1500L / min-3000L / min for the argon gas.

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