Titanium carbide microtube and its preparation method and application

Abstract

The present invention belongs to the field of inorganic non-metallic material preparation, and specifically relates to a titanium carbide micron tube and its preparation method and application. The preparation method comprises the following steps: in anhydrous ethanol solvent, SiC f The method comprises the following steps: taking Ti3SiC2 as a template and mixing it with Ti powder to obtain a mixed powder; adding the mixed powder to a mixed salt of NaCl and KCl, and carrying out a molten salt reaction under a protective atmosphere to obtain SiC fibers containing a Ti3SiC2 coating; and heat-treating the SiC fibers containing the Ti3SiC2 coating under vacuum conditions to obtain titanium carbide microtubes. The titanium carbide in the titanium carbide microtubes prepared by the present invention has good chemical stability and electrical conductivity, becoming a potential negative electrode material for lithium-ion batteries. Moreover, the microtube structure can provide a larger specific surface area and an electron transmission path, which is beneficial to the rapid embedding and de-embedding of lithium ions, thereby improving the capacity and cycle life of the battery.

Description

Technical Field

[0001] The present invention belongs to the field of inorganic non-metallic material preparation, and in particular relates to a titanium carbide micron tube and a preparation method and application thereof. Background Art

[0002] Titanium carbide (TiC) is an important non-oxide ceramic material with unique physical and chemical properties, including extremely high hardness, a high melting point, low density, and excellent electrical and thermal conductivity. Based on these characteristics, titanium carbide nanotubes (TiC) have demonstrated excellent performance in applications such as catalysts and electrode materials. However, issues such as production cost, environmental impact, and stability have also emerged. Titanium carbide microtubes could alleviate these problems to a certain extent.

[0003] The key to preparing TiC microtubes is how to control their micron-shaped structure and achieve high-purity TiC materials. Currently, the commonly used methods for preparing TiC microtubes include chemical vapor deposition (CVD), template method, solid-phase reaction method and other emerging nanomanufacturing technologies. The following are several main preparation methods: (1) Chemical vapor deposition (CVD) is a common technology for preparing TiC microtubes, which is widely used to prepare high-purity, structure-controlled ceramic materials. This method uses a gaseous precursor to react chemically at high temperature to deposit TiC on a substrate. (2) The template method uses a pre-designed template to deposit TiC on the surface or inside of the template, and then removes the template to obtain TiC microtubes. (3) The solid-phase reaction method uses a titanium source and a carbon source to react at high temperature to generate TiC. By selecting appropriate raw materials and reaction conditions, micron-shaped TiC materials can be obtained. (4) The sol-gel method is a method for preparing ceramic materials through a solution chemical route. This method forms a titanium-based sol, which is then gelated and carbonized at high temperature to form TiC microtubes. (5) Carbothermal reduction is a preparation method that generates TiC by reducing titanium compounds with a carbon source. It is often used to prepare nano- or micron-sized TiC materials.

[0004] However, these traditional preparation methods all have shortcomings. For example, the solid-phase reaction method has a high reaction temperature and a long reaction time, and the purity and morphology of the generated TiC microtubes cannot be precisely controlled, which to a certain extent limits the application range of TiC microtubes. Several other preparation methods have the problems of high preparation cost and complex process. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a titanium carbide microtube, a preparation method and application thereof. The titanium carbide in the titanium carbide microtube prepared by the present invention has good chemical stability and conductivity, becoming a potential negative electrode material for lithium-ion batteries. Moreover, the microtube structure can provide a large specific surface area and electron transmission path, which is conducive to the rapid insertion and deinsertion of lithium ions, thereby improving the capacity and cycle life of the battery.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for preparing titanium carbide microtubes comprises the following steps:

[0008] In anhydrous ethanol solvent, SiC f As a template, it is mixed with Ti powder, heated and stirred, evaporated and ground to obtain a mixed powder.

[0009] The mixed powder is added to a mixed salt of NaCl and KCl, and a molten salt reaction is carried out under a protective atmosphere. Ti reacts in situ with SiC on the surface of the silicon carbide fiber, and SiC fiber containing a Ti3SiC2 coating is obtained through interface decomposition and diffusion mechanisms.

[0010] Under vacuum conditions, the SiC fiber containing the Ti3SiC2 coating is heat treated, and the Ti3SiC2 is decomposed into TiC and volatile Si, forming a dense TiC layer on the outer layer of the SiC fiber. As the reaction proceeds, the SiC fiber is completely decomposed to generate carbon and volatile Si. The original template morphology of the SiC fiber is retained by the TiC, and the remaining Ti in the system further reacts with the carbon through diffusion, ultimately obtaining titanium carbide microtubes.

[0011] Since Ti reacts in situ with SiC on the surface of silicon carbide fiber to obtain a Ti3SiC2 coating of a certain thickness, the reaction process is as follows:

[0012] Ti+SiC→TiC+Si

[0013] Ti+2TiC+Si→Ti3SiC2

[0014] It is generated on the surface of SiC fiber to form a dense Ti3SiC2 phase. The reaction between Ti and SiC fiber surface is mainly carried out through interface decomposition and diffusion mechanism, and finally a stable Ti3SiC2 phase is formed.

[0015] Ti3SiC2 is a MAX phase material with a layered structure composed of Ti, Si and C. Under high temperature conditions, Ti3SiC2 will decompose to produce TiC, Si and other by-products: Ti3SiC2→3TiC+Si.

[0016] Under vacuum conditions, the Si atoms generated at high temperatures are easily volatilized, leaving behind a residue primarily composed of TiC. During decomposition and volatilization, the residual TiC diffuses and reorganizes at high temperatures to form a tubular structure. The SiC fibers serve as a substrate, providing a template for the nucleation and growth of TiC after the decomposition of Ti3SiC2. Titanium carbide has excellent chemical stability, and at high temperatures, the material tends to reduce its free energy. Therefore, during the decomposition process, TiC preferentially grows along the fiber surface, guided by the high temperature to form a micron-sized tubular structure.

[0017] Under vacuum and high temperature conditions (1800°C), after part of the product Si volatilizes, it will be accompanied by local gas phase reaction and material migration. The material loss and internal stress relaxation caused by volatilization further promote the formation of a hollow structure of micron tubes in TiC. In addition, in this system, the silicon of SiC fiber has a high vapor pressure and will volatilize rapidly under vacuum and high temperature conditions. The volatilized silicon causes SiC to lose the main element that supports its structural integrity. The carbon formed after decomposition generally remains temporarily in solid form, and then further diffuses, aggregates or reacts chemically with the surrounding substances (such as forming TiC). As a result, the fiber gradually decomposes completely and is eventually replaced by a TiC tubular structure. The vacuum environment greatly reduces the partial pressure around the volatile substance, which further increases the volatilization rate of Si and the migration rate of carbon, thereby accelerating the decomposition of SiC.

[0018] Formation mechanism of TiC microtubes

[0019] Initial stage: reaction layer formation

[0020] The Ti3SiC2 coating decomposes at high temperature to generate TiC, forming a thin layer covering the surface of the SiC fiber. The Si produced by the decomposition gradually volatilizes, and the residual Ti further reacts with SiC to generate more TiC.

[0021] Intermediate stage: morphological transformation

[0022] As the reaction progresses, the SiC fiber is gradually consumed, and the carbon diffuses and reacts with the Ti to form a dense TiC layer on the outer layer of the fiber. After the SiC fiber decomposition is complete, the growth rate of the carbon and Ti reaction varies between the fiber surface and the pore area, gradually forming a hollow structure.

[0023] Final stage: complete fiber conversion

[0024] SiC fibers are completely decomposed under high temperature and vacuum, Si evaporates completely, and the original template morphology of the fiber is retained by TiC. The remaining Ti further reacts with carbon through diffusion to form pure TiC microtubes.

[0025] The preparation of TiC microtubes by the raw materials and reaction conditions of the present invention relies on the following key mechanisms:

[0026] 1. SiC fiber provides a template, and the carbon produced by its decomposition provides the source material for TiC formation.

[0027] 2. The Ti3SiC2 coating decomposes to generate initial TiC and promotes the transformation of the fiber into a TiC structure.

[0028] 3. High temperature and vacuum work together to drive the volatilization of Si, ensuring the formation of pure TiC structure and retaining the tubular morphology of the fiber.

[0029] By rationally controlling the raw material ratio, coating thickness and reaction conditions, the morphology and properties of TiC microtubes can be precisely controlled.

[0030] In a preferred embodiment of the present invention, Ti powder and SiC f The molar ratio is 1:1~4.

[0031] In a preferred embodiment of the present invention, the molar ratio of NaCl to KCl is 1:1-4.

[0032] In a preferred embodiment of the present invention, the molar ratio of Ti powder to KCl is 1:10-15.

[0033] In a preferred embodiment of the present invention, the heat treatment temperature is 1800° C. to 1850° C., the heat treatment time is 40 min to 80 min, and the heat treatment heating rate is 5° C. / min to 10° C. / min.

[0034] In a preferred embodiment of the present invention, the molten salt reaction conditions are: first, heating to 1050°C to 1150°C at a rate of 2°C / min to 5°C / min, keeping warm for 20min to 40min, and then cooling to 400°C to 600°C at a rate of 3°C / min to 6°C / min for reaction.

[0035] Another object of the present invention is to provide a titanium carbide microtube prepared by any of the preparation methods described above, wherein the mass fraction of titanium in the titanium carbide microtube is 55% to 65%, and the mass fraction of carbon is 35% to 45%, which is 100% in total.

[0036] The titanium carbide microtubes have good chemical stability and conductivity, making them potential negative electrode materials for lithium-ion batteries; the microtube structure can provide a large specific surface area and electron transmission path, which is conducive to the rapid insertion and extraction of lithium ions, thereby improving the capacity and cycle life of the battery.

[0037] In a preferred embodiment of the present invention, the titanium carbide microtube is a tubular structure with a diameter of micron level.

[0038] The third object of the present invention is to provide a use of the titanium carbide microtubes described in any one of the above in a negative electrode material for a lithium ion battery.

[0039] The role and characteristics of raw material selection in the present invention:

[0040] SiC fiber as a template material has the following characteristics:

[0041] High temperature stability: SiC fiber does not decompose rapidly at 1800℃~1850℃, providing a physical support structure for the reaction.

[0042] Carbon source supply: SiC fiber decomposes at high temperature and releases carbon, which provides the necessary carbon source for the formation of TiC.

[0043] Ti3SiC2 coating material characteristics: Ti3SiC2 is a MAX phase material with a unique layered structure, which generates TiC and Si during thermal decomposition.

[0044] Mechanism of action: Ti3SiC2 decomposes into TiC and volatile Si at high temperature, which is conducive to the formation of TiC microtubes.

[0045] High-purity titanium

[0046] Reaction driving force: Ti reacts chemically with SiC fibers and the carbon of the decomposition product to form TiC.

[0047] Morphology control: Ti has a strong diffusion ability and can be evenly distributed and participate in the reaction, promoting the growth of tubular TiC structure.

[0048] NaCl and KCl

[0049] The mixture of NaCl and KCl can form a low melting point eutectic salt. The eutectic point of the NaCl-KCl system is about 657℃.

[0050] Molten salts can be used as solvents for high-temperature chemical reactions, promoting the dissolution of reactants and ion migration.

[0051] NaCl and KCl molten salts have strong fluidity at high temperatures and can evenly coat SiC fibers and titanium particles, ensuring full contact between the reactants and forming a uniform coating structure.

[0052] NaCl and KCl molten salts provide low-resistance channels for the diffusion of Ti, Si, and C, accelerating the migration of elements at the reaction interface.

[0053] Molten salt reduces the activation energy of the interface reaction between Ti and SiC, and can lower the reaction temperature of the two.

[0054] In a high-temperature environment, the molten salt acts to isolate the air, preventing the reactants (especially titanium) from oxidation and ensuring the effective progress of the reaction.

[0055] Key influence of reaction conditions

[0056] Effects of high temperature (1800℃~1850℃):

[0057] SiC decomposition: SiC fiber decomposes at 1800℃~1850℃ to generate free Si (volatile) and carbon (solid or diffused)

[0058] Ti3SiC2 decomposition: The coated Ti3SiC2 decomposes into TiC and volatile Si at high temperature:

[0059] Titanium diffusion and reaction: Titanium diffuses into the interface at high temperatures and reacts with the decomposed carbon to generate more TiC:

[0060] The role of vacuum environment:

[0061] Promote the removal of volatile products: Vacuum accelerates the volatilization of Si, making the reaction between carbon and titanium more complete and reducing the formation of side phases.

[0062] Lower the decomposition temperature: Under vacuum environment, the decomposition temperature of SiC and Ti3SiC2 is reduced, and the reaction rate is enhanced.

[0063] The role of fiber structure:

[0064] The aspect ratio and hollow morphology of SiC fibers provide a template for the tubular growth of TiC at high temperatures. As SiC gradually decomposes, the original fiber structure is replaced by TiC.

[0065] Compared with the prior art, the TiC microtube material of the present invention focuses more on improving the performance of the TiC microtube material, has a shorter reaction time, and the purity and morphology of the generated TiC microtubes can be more precisely controlled. In addition, the present invention does not require subsequent template removal, the steps are relatively simple, and the damage to the structure during the preparation process is less, thereby reducing the preparation cost.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] 1. The preparation method of titanium carbide microtubes provided by the present invention is to prepare SiC fThe method comprises the following steps: taking Ti3SiC2 as a template, mixing it with Ti powder, heating and stirring, evaporating and grinding to obtain a mixed powder; adding the mixed powder to a mixed salt of NaCl and KCl, and performing a molten salt reaction under a protective atmosphere, wherein Ti reacts with SiC on the surface of the silicon carbide fiber in situ, and a SiC fiber containing a Ti3SiC2 coating is obtained through an interface decomposition and diffusion mechanism; heat-treating the SiC fiber containing the Ti3SiC2 coating under vacuum conditions, wherein in the initial stage of the reaction, the Ti3SiC2 coating decomposes at a high temperature to generate TiC, forming a thin layer covering the surface of the SiC fiber, the Si generated by the decomposition gradually volatilizes, and the residual Ti further reacts with the SiC to generate more TiC; and in the intermediate stage, as the reaction proceeds, the SiC fiber is gradually consumed, and carbon diffuses and reacts with Ti to generate a dense TiC layer on the outer layer of the fiber. After the SiC fiber decomposes, the growth rates of the carbon and titanium reactions differ between the fiber surface and the pores, gradually forming a hollow structure. In the final stage, the SiC fiber completely decomposes under high temperature and vacuum, completely evaporating the Si. The TiC retains the original template morphology of the fiber, and the remaining Ti further reacts with the carbon through diffusion to form pure TiC microtubes. The TiC microtube material of the present invention focuses on improving the performance of the TiC microtube material, with a shorter reaction time, allowing for more precise control of the purity and morphology of the resulting TiC microtubes. Furthermore, the present invention eliminates the need for subsequent template removal, resulting in a simpler process and less damage to the structure during the preparation process, reducing production costs.

[0068] 2. The titanium carbide microtubes of the present invention are obtained by high-temperature treatment of SiC fibers coated with Ti3SiC2. TiC has a unique electronic structure and physical properties, resulting in high electron mobility. The material of the TiC microtubes has excellent electrochemical properties. The material contains highly conductive metalloid TiC, resulting in excellent electrical conductivity.

[0069] 3. The titanium carbide microtube structure prepared by the present invention can provide a larger specific surface area and electron transmission pathway, which can effectively improve the capacity of the lithium battery. In addition, the microtube structure is conducive to the rapid insertion and extraction of lithium ions, which has the characteristic of improving the cycle life of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 In the figure, (a) to (c) are morphology images of titanium carbide microtubes prepared in Example 1 of the present invention at different magnifications.

[0071] Figure 2 This is the EDS energy spectrum of the titanium carbide microtube prepared in Example 1 of the present invention.

[0072] Figure 3 This is the XRD pattern of the titanium carbide microtubes prepared in Example 1 of the present invention.

[0073] Figure 4These are the resistivity test results of the titanium carbide microtubes prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0074] The following is a detailed description of the technical solutions in the embodiments of the present invention, using preferred embodiments and accompanying drawings in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0075] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0076] Example 1

[0077] A method for preparing titanium carbide microtubes comprises the following steps:

[0078] (1) SiC f The SiC and Ti powders were added into anhydrous ethanol and heated and stirred with a heating magnetic stirrer until all the ethanol was evaporated and discharged, and then ground and mixed again in a mortar. f The molar ratio of Ti powder to Ti powder is 2:1 to obtain a mixed powder.

[0079] (2) NaCl and KCl powders are mixed at a molar ratio of 10:10 to obtain a mixed salt, and the mixed powder and the mixed salt are mixed to obtain a final mixture for later use.

[0080] (3) The alumina crucible containing the above mixture is placed in a tubular furnace with argon flowing to carry out reaction preparation of SiC fibers containing Ti3SiC2 coating. The specific process of reaction preparation is: first, heating to 1100°C at a rate of 4°C / min, keeping warm for 30 minutes, and then cooling to 500°C at a rate of 4°C / min for reaction.

[0081] (4) After the sample is taken out, the mixed salt in the system is completely removed, and the deionized water is removed by drying to obtain the SiC fiber material containing the Ti3SiC2 coating, which is recorded as SiC f -T.

[0082] (5) Under vacuum conditions, SiC f -T is placed in a graphite carbon tube furnace for high-temperature heat treatment at 1800℃ for 60 minutes with a heating rate of 8℃ / min, and finally a TiC tube with a diameter of micron level is obtained.

[0083] Example 2

[0084] A method for preparing titanium carbide microtubes comprises the following steps:

[0085] (1) SiC f The SiC and Ti powders were added into anhydrous ethanol and heated and stirred with a heating magnetic stirrer until all the ethanol was evaporated and discharged, and then ground and mixed again in a mortar. f The molar ratio of Ti powder to Ti powder is 1:1 to obtain a mixed powder.

[0086] (2) NaCl and KCl powders are mixed at a molar ratio of 10:15 to obtain a mixed salt, and the mixed powder and the mixed salt are mixed to obtain a final mixture for later use.

[0087] (3) The alumina crucible containing the above mixture is placed in a tubular furnace with circulating argon gas to carry out reaction preparation of SiC fibers containing Ti3SiC2 coating. The specific process of reaction preparation is: first, heat to 1050°C at a rate of 2°C / min, keep warm for 20 minutes, and then cool to 400°C at a rate of 3°C / min for reaction.

[0088] (4) After the sample is taken out, the mixed salt in the system is completely removed, and the deionized water is removed by drying to obtain the SiC fiber material containing the Ti3SiC2 coating, which is recorded as SiC f -T.

[0089] (5) Under vacuum conditions, SiC f -T is placed in a graphite carbon tube furnace for high-temperature heat treatment at 1820℃ for 80 minutes with a heating rate of 5℃ / min, and finally a TiC tube with a diameter of micron level is obtained.

[0090] Example 3

[0091] A method for preparing titanium carbide microtubes comprises the following steps:

[0092] (1) SiC f The SiC and Ti powders were added into anhydrous ethanol and heated and stirred with a heating magnetic stirrer until all the ethanol was evaporated and discharged, and then ground and mixed again in a mortar. f The molar ratio of Ti powder to Ti powder is 4:1 to obtain a mixed powder.

[0093] (2) NaCl and KCl powders are mixed at a molar ratio of 10:12 to obtain a mixed salt, and the mixed powder and the mixed salt are mixed to obtain a final mixture for later use.

[0094] (3) The alumina crucible containing the above mixture is placed in a tubular furnace with argon flowing to carry out reaction preparation of SiC fibers containing Ti3SiC2 coating. The specific process of reaction preparation is: first, the temperature is raised to 1150°C at a rate of 5°C / min, kept at this temperature for 40 minutes, and then the temperature is lowered to 600°C at a rate of 6°C / min for reaction.

[0095] (4) After the sample is taken out, the mixed salt in the system is completely removed, and the deionized water is removed by drying to obtain the SiC fiber material containing the Ti3SiC2 coating, which is recorded as SiC f -T.

[0096] (5) Under vacuum conditions, SiC f -T is placed in a graphite carbon tube furnace for high-temperature heat treatment at 1850℃ for 40 minutes with a heating rate of 10℃ / min, and finally a TiC tube with a diameter of micron level is obtained.

[0097] Result Analysis

[0098] Figure 1 Figures (a) through (c) show the morphology of titanium carbide microtubes prepared in Example 1 of the present invention at different magnifications. The tubular titanium carbide has a diameter of approximately 10.80 μm and an inner wall thickness of approximately 1.70 μm. These results demonstrate that titanium carbide microtubes with uniform and dense microstructures, free of obvious pores, can be produced under these experimental conditions. By cutting the fiber raw material to different sizes, microtubes with varying aspect ratios can be produced.

[0099] Figure 2 This is the EDS spectrum of the titanium carbide microtube prepared in Example 1 of the present invention. Figure 2 The EDS spectrum analysis of the corresponding area is shown in Table 1. The mass fraction of Ti is 62.57%, and the mass fraction of C is 35.63%. Cu and Zn are the main components of the sample carrier in the instrument test, and their contents can be ignored. Figure 3 Phase analysis of the titanium carbide microtubes prepared in Example 1 of the present invention shows that the main phase composition of the titanium carbide microtubes is TiC, without other impurities, which proves that this method can prepare high-purity titanium carbide microtubes with uniform microstructure.

[0100] Table 1 Spectrum Figure 2 EDS energy spectrum analysis

[0101]

[0102] The conductivity data of the TiC microtubes prepared by the present invention are as follows: Figure 4As shown in Table 2, it can be seen that when the initial pressure is only 1.99 MPa, the conductivity of the titanium carbide microtube reaches 103.62 S / cm, which has high conductivity. As the pressure increases to 30.02 MPa, the conductivity of the titanium carbide microtube reaches 577.18 S / cm. Conductivity is generally positively correlated with the density and porosity of the material. Excessive porosity will cause the conductive channel of the material to be interrupted and the conductivity to decrease. Therefore, when the compaction density of the material increases, the porosity decreases and the conductivity increases. As the pressure increases, the contact between the powder particles becomes closer, thereby improving the conduction path of electrons and increasing the conductivity. The conductivity of the titanium carbide microtube material shows a gradual upward trend with increasing pressure until it reaches a certain saturation point, that is, further increasing the pressure has little effect on the conductivity.

[0103] Specifically, at low pressure, the contact between powder particles is incomplete, resulting in low compaction density, high porosity, and low conductivity. As pressure increases, the particles are gradually compacted, porosity decreases, and conductivity begins to increase.

[0104] Medium pressure stage: During this stage, as the compaction density increases, the contact between particles improves and the conductivity increases rapidly. At this point, the electron conduction path is gradually optimized, and the conductivity shows a significant upward trend.

[0105] High pressure stage: When the pressure reaches a certain value, the further compaction effect of the powder particles weakens and the increase in conductivity tends to saturate. At this time, the change in conductivity is relatively slow and the curve tends to be stable.

[0106] The TiC microtubes prepared by the present invention have a high compaction density and excellent crystal structure. Their electrical conductivity stabilizes with increasing pressure. This indicates that they can maintain excellent electrical conductivity under certain pressures and compaction densities, effectively conducting current. Furthermore, this performance is relatively stable under environmental conditions (such as temperature and pressure). They can be used as electrode materials for devices such as batteries, capacitors, or electrolyzers, meeting modern demands for high-performance, high-temperature-resistant, and highly conductive materials, while improving their efficiency and stability.

[0107] Table 2 Conductivity data of TiC microtubes

[0108]

[0109] In summary, the preparation method of titanium carbide microtubes provided by the present invention is to prepare SiC fThe method comprises the following steps: taking Ti3SiC2 as a template, mixing it with Ti powder, heating and stirring, evaporating and grinding to obtain a mixed powder; adding the mixed powder to a mixed salt of NaCl and KCl, and carrying out a molten salt reaction under a protective atmosphere, wherein Ti reacts with SiC on the surface of the silicon carbide fiber in situ, and obtains a SiC fiber containing a Ti3SiC2 coating through an interface decomposition and diffusion mechanism; heat-treating the SiC fiber containing the Ti3SiC2 coating under vacuum conditions, wherein in the initial stage, the Ti3SiC2 coating decomposes at a high temperature to generate TiC, forming a thin layer covering the surface of the SiC fiber, the Si generated by the decomposition gradually volatilizes, and the residual Ti further reacts with the SiC to generate more TiC; and in the intermediate stage, as the reaction proceeds, the SiC fiber is gradually consumed, and carbon diffuses and reacts with Ti to generate a dense TiC layer on the outer layer of the fiber. After the SiC fiber decomposes, the growth rates of the carbon and titanium reactions differ between the fiber surface and the pores, gradually forming a hollow structure. In the final stage, the SiC fiber completely decomposes under high temperature and vacuum, completely evaporating the Si. The TiC retains the original template morphology of the fiber, and the remaining Ti further reacts with the carbon through diffusion to form pure TiC microtubes. The TiC microtube material of the present invention focuses on improving the performance of the TiC microtube material, with a shorter reaction time, allowing for more precise control of the purity and morphology of the resulting TiC microtubes. Furthermore, the present invention eliminates the need for subsequent template removal, resulting in a simpler process and less damage to the structure during the preparation process, reducing production costs.

[0110] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes preferred embodiments. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0111] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing titanium carbide microtubes, characterized in that: The following steps are involved: In anhydrous ethanol solvent, SiC f As a template, it is mixed with Ti powder, heated and stirred, evaporated and ground to obtain a mixed powder; The mixed powder is added to a mixed salt of NaCl and KCl, and a molten salt reaction is carried out under a protective atmosphere, whereby Ti reacts in situ with SiC on the surface of the silicon carbide fiber, and SiC fibers containing a Ti3SiC2 coating are obtained through an interface decomposition and diffusion mechanism; The SiC fiber containing the Ti3SiC2 coating is heat-treated under vacuum conditions, whereby the Ti3SiC2 decomposes into TiC and volatile Si, forming a dense TiC layer on the surface of the SiC fiber. As the reaction proceeds, the SiC fiber is completely decomposed to generate carbon and volatile Si, while the original template morphology of the SiC fiber is retained by the TiC. The remaining Ti in the system further reacts with the carbon through diffusion, ultimately obtaining titanium carbide microtubes. The heat treatment temperature is 1800° C. to 1850° C., the heat treatment time is 40 min to 80 min, and the heat treatment heating rate is 5° C. / min to 10° C. / min; The molten salt reaction conditions are as follows: first, heating to 1050°C to 1150°C at a rate of 2°C / min to 5°C / min, keeping warm for 20min to 40min, and then cooling to 400°C to 600°C at a rate of 3°C / min to 6°C / min for reaction.

2. The method for preparing titanium carbide microtubes according to claim 1, characterized in that: Ti powder and SiC f The molar ratio is 1:1~4.

3. The method for preparing titanium carbide microtubes according to claim 1, characterized in that: The molar ratio of NaCl to KCl is 1:1-4.

4. The method for preparing titanium carbide microtubes according to claim 1, characterized in that: The molar ratio of Ti powder to KCl is 1:10-15.

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