Silicon carbide material as well as preparation method and application thereof

Abstract

The invention relates to the field of materials, in particular to a silicon carbide material and a preparation method and application thereof. The silicon carbide material is formed by agglomeration of spherical structures woven by nanofibers, the section of the silicon carbide material is of a layered irregular sheet structure, and the irregular sheet structure is composed of multiple layers of silicon carbide. The preparation method comprises the following steps: preparing the silicon carbide material through a chemical vapor deposition method; wherein reaction gas adopted by the chemical vapor deposition method comprises silicon source gas and carbon source gas; the flow rate of the silicon source gas is 1-30 slm, the flow rate of the carbon source gas is 1-30 slm, the temperature adopted by the chemical vapor deposition method is 900-1500 DEG C, the pressure is 5-20 KPa, and the deposition time is 1-20 hours. The silicon carbide material is of a multi-layer layered structure, the surface reaction activity and physical adsorption capacity of the material can be enhanced, the impact resistance and toughness of the material are enhanced, the material shows better mechanical performance in a high-stress environment, and the silicon carbide material has a certain application prospect in electronic devices or biosensors.

Description

Technical Field

[0001] The present invention relates to the field of materials, and in particular to a silicon carbide material and a preparation method and application thereof. Background Art

[0002] Silicon carbide materials are widely used in electronics, semiconductors, machinery, chemicals, energy and other fields due to their high hardness, high melting point, excellent oxidation resistance, low thermal expansion coefficient, high thermal conductivity, chemical stability, wide bandgap semiconductors and high frequency and high efficiency. Silicon carbide has a variety of polymorphic forms (such as 4H-SiC, 6H-SiC, 3C-SiC, etc.), and different forms of SiC have different crystal structures and properties. Among them, β-SiC belongs to the cubic crystal system, also known as cubic silicon carbide. The main preparation methods of silicon carbide are the Acheson method: high-purity quartz sand and petroleum coke are reacted in a resistance furnace at high temperature (about 2200℃-2500℃) to generate silicon carbide, which is mainly used in the production of abrasives and refractory materials. The generated SiC crystals are usually black or green, with larger particles. Chemical Vapor Deposition (CVD) decomposes silicon- and carbon-containing gases (such as methyltrichlorosilane or acetylene and silane) at high temperatures (about 1000°C-1400°C), and the reactants in the gas phase are deposited on the surface of the substrate to form a silicon carbide film. It can produce high-purity SiC films, which are suitable for manufacturing semiconductor devices and high-temperature structural materials. In addition, the solid-phase reaction method mainly reacts solid-phase mixed silicon and carbon powder at high temperatures (about 1400°C-1600°C) to directly generate silicon carbide. This method is simple and suitable for large-scale production, and is usually used to manufacture structural ceramics and refractory materials. In the preparation methods such as self-propagating high-temperature synthesis method and molten salt method, silicon carbide exists in the form of polycrystalline silicon carbide, single crystal silicon carbide, silicon carbide fiber, silicon carbide film, nano silicon carbide powder, etc., but the morphology of silicon carbide obtained by the existing preparation method is relatively fixed, lacks a complex multi-layered structure, and has poor toughness, impact resistance and other properties, which limits the application scenarios. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a silicon carbide material and a preparation method and application thereof. The silicon carbide material has a multi-layered structure, which can enhance the surface reactivity and physical adsorption capacity of the material, enhance the impact resistance and toughness of the material, and make it show better mechanical properties under high stress environment, and has certain application prospects in electronic devices or biosensors. In addition, the preparation method of the present invention is simple and greatly simplifies the preparation process of existing layered materials.

[0004] To this end, the first aspect of the present invention provides a silicon carbide material, which is formed by agglomerating a spherical structure woven from nanofibers, and the cross-section of the silicon carbide material is arranged with an irregular sheet structure, and the irregular sheet structure is composed of multiple layers of silicon carbide.

[0005] The present invention provides a silicon carbide material with a special morphology, which is composed of interwoven nanoscale structural units. Such a woven morphology can provide a higher specific surface area and porosity, and enhance the surface reactivity and physical adsorption capacity of the material. At the same time, the cross-section of the silicon carbide is arranged with an irregular sheet structure, and the irregular sheet is composed of multiple layers of silicon carbide, which helps to absorb and disperse stress, reduce cracks and debonding phenomena at the interface, enhance the impact resistance and toughness of the material, and make it show better mechanical properties under high stress environments. In addition, the multilayer structure can also help to realize more complex functions in electronic devices. For example, in photoelectric conversion and thermoelectric materials, the layered structure helps to regulate the conduction of charge or heat flow; it can also be used as a biosensor in detection tasks that require high sensitivity and high selectivity.

[0006] According to an embodiment of the present invention, the diameter of the spherical structure is 2-20 μm.

[0007] According to an embodiment of the present invention, the diameter of the nanofiber is 300-2000 nm.

[0008] According to an embodiment of the present invention, the thickness of a single layer of the irregular flaky structure is 50 nm-300 nm.

[0009] According to an embodiment of the present invention, the length of the irregular sheet-like structure is 1 μm-10 μm.

[0010] A second aspect of the present invention provides a method for preparing the silicon carbide material according to the first aspect, comprising the following steps:

[0011] Preparing the silicon carbide material by chemical vapor deposition;

[0012] Wherein, the reaction gas used in the chemical vapor deposition method includes silicon source gas and carbon source gas;

[0013] The flow rate of the silicon source gas is 1slm-30slm, the flow rate of the carbon source gas is 1slm-30slm, the temperature adopted by the chemical vapor deposition method is 900°C-1500°C, the pressure is 5KPa-20KPa, and the deposition time is 1h-20h.

[0014] The present invention can obtain the aforementioned silicon carbide material with special morphology in one step by limiting the reaction conditions during the chemical vapor deposition process without switching or changing parameters. The preparation method is simple, efficient and easy to scale up industrially.

[0015] According to an embodiment of the present invention, the silicon source gas includes at least one of silane, monochlorosilane, dichlorosilane, trichlorosilane, silicon tetrachloride, trichloromethylsilane, and dichlorodimethylsilane.

[0016] According to an embodiment of the present invention, the carbon source gas includes at least one of methane, propane, propylene, ethylene, acetylene, trichloromethylsilane, and dichlorodimethylsilane.

[0017] According to an embodiment of the present invention, the chemical vapor deposition method is performed in an inert gas, and the inert gas includes at least one of argon, nitrogen, and helium.

[0018] According to an embodiment of the present invention, the flow rate of the inert gas is 1slm-50slm.

[0019] According to an embodiment of the present invention, the diluent gas used in the chemical vapor deposition method includes hydrogen.

[0020] According to an embodiment of the present invention, the flow rate of the dilution gas is 1slm-200slm.

[0021] According to an embodiment of the present invention, the substrate used in the chemical vapor deposition method is a carbon material.

[0022] According to an embodiment of the present invention, the preparation method further comprises:

[0023] The reaction equipment is subjected to vacuum treatment, and the silicon carbide material is prepared by chemical vapor deposition.

[0024] According to an embodiment of the present invention, the vacuum treatment makes the vacuum degree of the reaction equipment 0-10Pa.

[0025] The third aspect of the present invention provides the use of the silicon carbide material described in the first aspect or the silicon carbide material obtained according to the preparation method described in the second aspect in a biosensor and / or an electronic device.

[0026] The silicon carbide material provided by the present invention has a multi-layered structure and has good toughness and impact resistance, which helps to realize more complex functions in electronic devices, such as in photoelectric conversion and thermoelectric materials, it helps to regulate the conduction of charge or heat flow; its complex surface morphology and layered structure can also be used as a biosensor in detection tasks requiring high sensitivity and high selectivity.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0029] Figure 1 A high-magnification surface SEM image of a silicon carbide material obtained by a preparation method other than the present invention is shown;

[0030] Figure 2 A low-magnification surface SEM image of the silicon carbide material prepared in Example 1 of the present invention is shown;

[0031] Figure 3 A high-magnification surface SEM image of the silicon carbide material prepared in Example 1 of the present invention is shown;

[0032] Figure 4 shows a cross-sectional SEM image of the silicon carbide material prepared in Example 1 of the present invention;

[0033] Figure 5-6 The high-magnification cross-sectional SEM image of the silicon carbide material prepared in Example 1 of the present invention is shown. Figure 6 This is a SEM image obtained under higher magnification conditions;

[0034] Figure 7-8 The high-magnification cross-sectional SEM image of the silicon carbide material prepared in Comparative Example 1 of the present invention is shown. Figure 8 This is a SEM image obtained under higher magnification conditions;

[0035] Fig. 9 The displacement-load diagram of the silicon carbide materials prepared in Example 1 of the present invention and Comparative Example 1 in a three-point bending test is shown. DETAILED DESCRIPTION

[0036] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0037] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0038] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0039] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which the present invention belongs.

[0040] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0041] As used herein, the terms "optionally", "optional" or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0042] Existing silicon carbide structures are mostly nanopowders, single crystals, dense coatings of polycrystalline, and sintered silicon carbide structural ceramics. Each use is different, and there are few reports on complex morphology multilayer silicon carbide materials. The toughness, impact resistance and other properties of the obtained silicon carbide materials are poor, and the actual application scenarios are limited. In addition, the existing preparation of layered materials generally needs to be achieved through the following methods: (1) through multiple depositions and intermittent heating; (2) after each layer is deposited, the process parameters are changed to introduce some changes so that the characteristics of each layer are different to form a layered structure; (3) different carbon sources and silicon sources or concentrations are used alternately to form different microstructures or stress states between each layer to produce a layered effect; (4) a template structure is etched or deposited on the substrate, and then SiC is deposited on the top of the template so that SiC forms a layered structure on the template and then the template is removed to obtain a layered SiC structure. The above preparation methods are relatively complicated and difficult to scale up industrially.

[0043] According to an embodiment of the present invention, the first aspect of the present invention provides a silicon carbide material, the morphology of which can be seen in Figure 1-5 The silicon carbide material is formed by the aggregation of spherical structures formed by cross-weaving of self-assembled nanofibers (see Figure 2 ), the cross-section of the silicon carbide material is arranged in an irregular flaky structure (see Figure 4 ), the irregular flake structure is composed of multiple layers of silicon carbide (see Figure 5 ).

[0044] According to a specific embodiment of the present invention, the arrangement of the irregular sheet-like structures is not particularly limited, for example, they are arranged in a "flower-like" manner.

[0045] According to a specific embodiment of the present invention, the diameter of the spherical structure is 2-20 μm. As some specific examples, the diameter of the spherical structure may be 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, etc. The high specific surface area and multi-level structural characteristics of the spherical structure can provide multi-directional stress distribution when the material is subjected to tensile or bending loads, so that the impact force can be evenly distributed in all directions of the material, reducing the possibility of local stress concentration and damage. At the same time, the porous characteristics of the spherical structure help absorb and dissipate impact energy, thereby improving the impact resistance of the material.

[0046] According to a specific embodiment of the present invention, the diameter of the nanofiber is 300-2000nm. As some specific examples, the diameter of the nanofiber can be 300nm, 500nm, 1000nm, 1500nm, 2000nm, etc. In the present invention, the nanofiber has a smaller weaving angle during weaving into a spherical structure, which can improve the stability of the material, disperse stress, and reduce local damage.

[0047] According to a specific embodiment of the present invention, the length of the irregular sheet structure is not particularly limited. As some specific examples, the length of the irregular sheet structure may be 1 μm-10 μm. The length of the irregular sheet structure should be understood as the length of the longest diagonal line in the structure.

[0048] According to a specific embodiment of the present invention, the thickness of the single layer of the irregular flaky structure is nanometer-level. As some specific examples, the thickness of the single layer of the irregular flaky structure is 50nm-300nm. The silicon carbide material prepared by the present invention has a reasonable thickness of the single layer of the irregular flaky structure, which is conducive to improving the stability of the material, dispersing stress, and reducing local damage.

[0049] According to an embodiment of the present invention, a second aspect of the present invention provides a method for preparing the silicon carbide material according to the first aspect, comprising the following steps:

[0050] Preparing the silicon carbide material by chemical vapor deposition;

[0051] Wherein, the reaction gas used in the chemical vapor deposition method includes silicon source gas and carbon source gas;

[0052] The flow rate of the silicon source gas is 1slm-30slm, the flow rate of the carbon source gas is 1slm-30slm, the temperature adopted by the chemical vapor deposition method is 900°C-1500°C, the pressure is 5KPa-20KPa, and the deposition time is 1h-20h.

[0053] The present invention controls the overall gas flow rate at a relatively low condition, the precursor partial pressure at a relatively low level, and the temperature at a relatively low temperature, so as to grow a silicon carbide structure whose surface is a spherical structure woven by nanofibers. If the precursor partial pressure is too low or the overall flow rate is too low, and is lower than the parameter range defined by the preparation method of the present invention, it will lead to directional growth to generate fibrous silicon carbide (such as Figure 1 As shown), otherwise, dense structured silicon carbide is formed. In addition, the present invention controls the concentration of the reaction gas, deposition time and other conditions in the chemical vapor deposition process to control the growth of silicon carbide materials with a multi-layered structure in cross section through the following mechanisms: (1) The reaction gas concentration is adjusted within a suitable range to reduce the nucleation density, so that the existing crystal nuclei grow rapidly and new crystal nuclei are formed slowly, resulting in a weakened interface bonding between the grains, thereby forming a layered structure in the subsequent deposition process; (2) The deposition time is controlled to reconstruct the substrate surface, resulting in a structural difference between the SiC layer deposited earlier and the layer deposited later, forming a layered interface, and growing a multi-layered structure; (3) Under a limited reaction gas concentration, the deposition rate is slowed down, resulting in uneven stress distribution in the film layer, and stress accumulation forms different stress states at different deposition stages. This stress difference causes the bonding force between the layers to weaken, and finally forms a layered structure; (4) Under a limited gas concentration, local reaction zones may be undersaturated, which may cause the film layer to form different structural characteristics at different locations, thereby producing a layered structure.

[0054] According to a specific embodiment of the present invention, the flow rate of the silicon source gas is 1slm-30slm. As some specific examples, the flow rate of the silicon source gas may be 1slm, 5slm, 10slm, 15slm, 20slm, 25slm, 30slm, etc.

[0055] According to a specific embodiment of the present invention, the type of the silicon source gas is not particularly limited, as long as it can provide silicon atoms. As some specific examples, the silicon source gas includes but is not limited to silane, monochlorosilane, dichlorosilane, trichlorosilane, silicon tetrachloride, trichloromethylsilane, and dichlorodimethylsilane.

[0056] According to a specific embodiment of the present invention, the flow rate of the carbon source gas is 1slm-30slm. As some specific examples, the flow rate of the carbon source gas may be 1slm, 5slm, 10slm, 15slm, 20slm, 25slm, 30slm, etc.

[0057] According to a specific embodiment of the present invention, the type of the carbon source gas is not particularly limited, as long as it can provide carbon atoms. As some specific examples, the carbon source gas includes but is not limited to methane, propane, propylene, ethylene, acetylene, trichloromethylsilane, and dichlorodimethylsilane.

[0058] According to a specific embodiment of the present invention, the temperature adopted in the chemical vapor deposition method is 900°C-1500°C. As some specific examples, the temperature adopted in the chemical vapor deposition method may be 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C, etc.

[0059] According to a specific embodiment of the present invention, the pressure used in the chemical vapor deposition method is 5KPa-20KPa. As some specific examples, the pressure used in the chemical vapor deposition method may be 5KPa, 10KPa, 15KPa, 20KPa, etc.

[0060] According to a specific embodiment of the present invention, the deposition time adopted by the chemical vapor deposition method is 1h-20h. As some specific examples, the deposition time adopted by the chemical vapor deposition method is 1h, 5h, 10h, 15h, 20h, etc.

[0061] According to a specific embodiment of the present invention, the chemical vapor deposition method is carried out in an inert gas. The type of the inert gas is not particularly limited. As some specific examples, it includes but is not limited to at least one of argon, nitrogen, and helium.

[0062] According to a specific embodiment of the present invention, the flow rate of the inert gas is 1slm-50slm. As some specific examples, the flow rate of the inert gas is 1slm, 10slm, 20slm, 30slm, 40slm, 50slm, etc.

[0063] According to a specific embodiment of the present invention, the chemical vapor deposition process also includes a diluent gas, which can participate in the reaction and promote the decomposition of the reaction gas. The type of the diluent gas is not particularly limited. As some specific examples, the diluent gas includes but is not limited to hydrogen.

[0064] According to a specific embodiment of the present invention, the flow rate of the dilution gas is 1slm-200slm. As some specific examples, the flow rate of the dilution gas is 1slm, 50slm, 100slm, 150slm, 200slm, etc.

[0065] According to a specific embodiment of the present invention, the preparation method further comprises:

[0066] The reaction equipment is subjected to a vacuum treatment, and the silicon carbide material is prepared by chemical vapor deposition. The vacuum treatment makes the vacuum degree of the reaction equipment 0-10 Pa, and the pressure is maintained, and then the silicon carbide material is deposited.

[0067] According to a specific embodiment of the present invention, the substrate used in the chemical vapor deposition method is a carbon material, including but not limited to graphite or other carbon composite materials.

[0068] According to a specific embodiment of the present invention, the preparation method further comprises: pre-treating the substrate. The pre-treating method is not limited, and as some specific examples, the substrate may be ultrasonically cleaned and dried to remove powder attached to the surface and reduce surface impurities.

[0069] According to a specific embodiment of the present invention, the preparation method may be specifically as follows: adjusting the temperature of the reaction chamber of the chemical vapor deposition equipment to 900°C-1500°C and the pressure to 5KPa-20KPa for insulation; introducing inert gas, diluent gas, reaction gas and other gases for deposition, the deposition time is 1h-20h, and after the deposition is completed, the temperature is naturally lowered to room temperature and the sample is taken out.

[0070] According to a specific embodiment of the present invention, the third aspect of the present invention provides the use of the silicon carbide material described in the first aspect or the silicon carbide material obtained according to the preparation method described in the second aspect in a biosensor and / or electronic device.

[0071] The silicon carbide material provided by the present invention has a multi-layered structure and has good toughness and impact resistance, which helps to realize more complex functions in electronic devices, such as in photoelectric conversion and thermoelectric materials, it helps to regulate the conduction of charge or heat flow; its complex surface morphology and layered structure can also be used as a biosensor in detection tasks requiring high sensitivity and high selectivity.

[0072] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0073] Example 1

[0074] 1. Substrate pretreatment:

[0075] Ultrasonic cleaning and drying of the graphite substrate to remove the powder attached to the surface and reduce surface impurities;

[0076] 2. Place the base and vacuum:

[0077] The substrate pretreated in the first step is placed in the chemical vapor deposition equipment used for the experiment, and the equipment is evacuated to 0Pa and the pressure is maintained;

[0078] 3. Preparation of multilayer silicon carbide materials:

[0079] The temperature of the chemical vapor deposition equipment reaction chamber was adjusted to 1000°C, and the pressure of the deposition reaction chamber was adjusted to 5KPa for heat preservation; inert gas Ar 3slm and diluent gas H 2 24slm, reaction gas trichloromethylsilane 5slm, deposition for 3h, a flower-shaped multilayered silicon carbide with a thickness of 100μm can be obtained. For specific morphology, see Figure 1-5 The cross section of silicon carbide has an irregular flake structure, see Figure 4 The length of the flake structure in the circle is 8 μm, and the thickness of the single layer of the irregular flake structure is 300 nm (see Figure 5 ).

[0080] Example 2

[0081] 1. Substrate pretreatment:

[0082] Ultrasonic cleaning and drying of the carbon / carbon composite material matrix to remove powder attached to the surface and reduce surface impurities;

[0083] 2. Place the base and vacuum:

[0084] The substrate pretreated in the first step is placed in the chemical vapor deposition equipment used for the experiment, and the equipment is evacuated to 0Pa and the pressure is maintained;

[0085] 3. Preparation of multilayer silicon carbide materials:

[0086] The temperature of the chemical vapor deposition equipment reaction chamber was adjusted to 1400°C, and the pressure of the deposition reaction chamber was adjusted to 18KPa for heat preservation; inert gas Ar 40slm and diluent gas H 2 160slm, reaction gas trichloromethylsilane 30slm, deposition 7h, can obtain silicon carbide with a flower-like multilayer structure with a thickness of 300μm.

[0087] Comparative Example 1

[0088] 1. Substrate pretreatment:

[0089] Ultrasonic cleaning and drying of the carbon / carbon composite material matrix to remove powder attached to the surface and reduce surface impurities;

[0090] 2. Place the base and vacuum:

[0091] The substrate pretreated in the first step is placed in the chemical vapor deposition equipment used for the experiment, and the equipment is evacuated to 0Pa and the pressure is maintained;

[0092] 3. Preparation of multilayer silicon carbide materials:

[0093] The temperature of the chemical vapor deposition equipment reaction chamber was adjusted to 800°C, and the pressure of the deposition reaction chamber was adjusted to 25KPa for heat preservation; inert gas Ar 1slm and diluent gas H 2 40slm, reaction gas trichloromethylsilane 35slm, deposition for 5h, a silicon carbide with a dense film structure in cross section can be obtained. For specific morphology, see Figure 6-7 Under the conditions that the temperature is too low and below the temperature range specified by the preparation method of the present invention, and the pressure and gas flow rate are too high and above the parameter range specified by the preparation method of the present invention, dense silicon carbide with no stratification in the cross section and no flower-like characteristic structure will grow.

[0094] The impact resistance and toughness test data of the silicon carbide materials prepared in Example 1 and Comparative Example 1 are shown in Table 1; the displacement-load diagram of the silicon carbide materials prepared in Example 1 and Comparative Example 1 in the three-point bending test is shown in Fig. 9 shown.

[0095] Table 1

[0096] Bending strength Fracture toughness Comparative Example 1 Sample 86.7MPa <![CDATA[3.90MPa·m 1 / 2 ]]> Example 1 Sample 114.22MPa <![CDATA[4.26MPa·m 1 / 2 ]]>

[0097] The impact resistance of the material is characterized by the value of the flexural strength. The greater the flexural strength, the better the impact resistance. It can be seen from the data in Table 1 that compared with Comparative Example 1, the impact resistance and toughness of the silicon carbide material prepared in Example 1 are significantly improved, and its mechanical properties are relatively excellent, which can be applied to more application scenarios; in addition, Fig. 9 It can be seen that, in general, the fracture form of the sample is brittle fracture. The fracture failure of the specimen occurs very quickly, and the displacement value is relatively small. In the initial stage of loading, the displacement load curve grows roughly linearly. As the load continues to increase, cracks appear inside the specimen and gradually grow. After reaching the peak load, the curve shows a downward trend until the specimen fails as a whole.

[0098] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0099] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A silicon carbide material, characterized in that: The silicon carbide material is formed by agglomeration of a spherical structure woven from nanofibers. The cross section of the silicon carbide material is a layered irregular sheet structure, and the irregular sheet structure is composed of multiple layers of silicon carbide.

2. The silicon carbide material according to claim 1, characterized in that: The diameter of the spherical structure is 2-20 μm; Optionally, the nanofibers have a diameter of 300-2000 nm.

3. The silicon carbide material according to claim 1, characterized in that: The thickness of the single layer of the irregular flaky structure is 50nm-300nm; Optionally, the length of the irregular flake structure is 1 μm-10 μm.

4. A method for preparing the silicon carbide material according to any one of claims 1 to 3, characterized in that: The following steps are involved: Preparing the silicon carbide material by chemical vapor deposition; Wherein, the reaction gas used in the chemical vapor deposition method includes silicon source gas and carbon source gas; The flow rate of the silicon source gas is 1slm-30slm, the flow rate of the carbon source gas is 1slm-30slm, the temperature adopted by the chemical vapor deposition method is 900°C-1500°C, the pressure is 5KPa-20KPa, and the deposition time is 1h-20h.

5. The preparation method according to claim 4, characterized in that: The silicon source gas includes at least one of silane, monochlorosilane, dichlorosilane, trichlorosilane, silicon tetrachloride, trichloromethylsilane, and dichlorodimethylsilane; Optionally, the carbon source gas includes at least one of methane, propane, propylene, ethylene, acetylene, trichloromethylsilane, and dichlorodimethylsilane.

6. The preparation method according to claim 4, characterized in that: The chemical vapor deposition method is carried out in an inert gas, wherein the inert gas includes at least one of argon, nitrogen and helium; Optionally, the flow rate of the inert gas is 1slm-50slm.

7. The preparation method according to claim 4, characterized in that: The diluent gas used in the chemical vapor deposition method includes hydrogen; Optionally, the flow rate of the dilution gas is 1slm-200slm.

8. The preparation method according to claim 4, characterized in that: The substrate used in the chemical vapor deposition method is a carbon material.

9. The preparation method according to claim 4, characterized in that: The preparation method further comprises: Performing vacuum treatment on the reaction equipment and preparing the silicon carbide material by chemical vapor deposition; Optionally, the vacuum treatment makes the vacuum degree of the reaction equipment 0-10Pa.

10. Use of the silicon carbide material according to any one of claims 1 to 3 or the silicon carbide material obtained according to the preparation method according to any one of claims 4 to 9 in biosensors and / or electronic devices.

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