Carbon nanotube-silicon nitride nanowire composite material and preparation method and application thereof

Abstract

The invention discloses a carbon nanotube-silicon nitride nanowire composite material and a preparation method and application thereof.The preparation method comprises the steps that polysilazane, acetone and ferrocene are mixed and then subjected to standing and curing, and a product A is obtained; grinding the product A, and placing the product A between two pieces of carbon paper which are stacked in parallel; carrying out heat treatment on the ground powder in a nitrogen atmosphere to obtain a product B; and placing the product B in a tubular vapor deposition furnace, and injecting a mixed solution of ferrocene, ethanol and ethylenediamine into the tubular vapor deposition furnace by using argon as carrier gas for reaction to prepare the carbon nanotube-silicon nitride nanowire composite material. According to the method, the feather-shaped carbon nanotube array with directionality and structural continuity is constructed on the surface of the silicon nitride nanowire in situ through the chemical vapor deposition technology, so that the resistivity is greatly reduced, the overall conductivity of the material is improved, and the method has wide potential prospects in the field of electronic devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and relates to a carbon nanotube - silicon nitride nanowire composite material, a preparation method thereof, and an application thereof. Background Art

[0002] As a typical ceramic material with high strength and high temperature stability, silicon nitride nanowires have been widely used in the fields of structural reinforcement, thermal protection, etc. However, its intrinsic resistivity is as high as 10 5 ~10 7 Ω·cm, belonging to insulating materials, which severely limits its application in emerging devices such as flexible electronics, conductive scaffolds, and micro sensors. Therefore, reducing the resistivity of silicon nitride nanowires and endowing them with controllable electrical conductivity have become the key to promoting their transformation from traditional structural ceramics to functional integrated materials. By reducing its resistivity, it not only has the thermal stability of ceramics but also can undertake the function of constructing a conductive path, broadening its application space in the fields of electronic devices and intelligent materials.

[0003] The literature "Influence of Conductive Nano - TiC on Microstructural Evolution of Si3N4 - Based Nanocomposites in Spark Plasma Sintering", Ching L, Horng L, Chang W, et al. J. Am. Ceram. Soc. 2011, 94, 959 - 967. This study shows that silicon nitride composites containing 30% volume of TiC 0.5 N 0.5 exhibit good electrical conductivity in the range of room temperature to 400 °C, with a resistivity of 15.5 Ω·cm. The literature "Electrical resistivity of Si3N4 - SiC - MeSi2 (Me = Nb, Mo, W, Zr) composites", E Zschippang, H Klemm, M Herrmann, et al.. J. Ceram. Sci. Tech. 2013, 4, 197 - 206. This study shows that by adding metal silicide NbSi2 to the Si3N4 - SiC matrix, the resistivity of the composite material is 10 Ω·cm.

[0004] Although the above - mentioned studies have improved the performance of silicon nitride, its resistivity is still relatively large, making it difficult to meet the requirements for high - conductivity materials. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a carbon nanotube-silicon nitride nanowire composite material, a preparation method and an application thereof, so as to solve the technical problem of relatively high resistivity of silicon nitride nanowires in the prior art.

[0006] The present invention is realized through the following technical solutions:

[0007] A preparation method of a carbon nanotube-silicon nitride nanowire composite material includes the following steps:

[0008] S1: Mix polyazidosilane, acetone and ferrocene, and let it stand at room temperature. After the solution solidifies, product A is obtained;

[0009] S2: Grind the product A, and place the ground powder between two parallelly stacked carbon papers; then, under a nitrogen atmosphere, perform heat treatment on the ground powder to obtain product B;

[0010] S3: Place product B in a tubular chemical vapor deposition furnace, heat the system to 780-810 °C under an argon atmosphere, and then use argon as the carrier gas to inject a mixed solution of ferrocene, ethanol and ethylenediamine into the tubular chemical vapor deposition furnace for reaction to obtain the carbon nanotube-silicon nitride nanowire composite material.

[0011] Preferably, the mass ratio of polyazidosilane to ferrocene is (7-9):1; the volume ratio of polyazidosilane to acetone is 1:(0.5-1).

[0012] Preferably, in step S1, let it stand at room temperature for 5-10 days.

[0013] Preferably, in step S2, grind to a D 50 of 1-10 μm.

[0014] Preferably, in step S2, the heat treatment process is specifically: first maintain at a temperature of 300-350 °C for 2-3 h, then heat up to 1400-1500 °C, keep the temperature constant for 3-4 h, and cool to room temperature with the furnace.

[0015] Preferably, in step S3, the mass ratio of ferrocene to ethanol is 1:(90-100); the mass ratio of ferrocene to ethylenediamine is 1:(15-17).

[0016] Preferably, in step S3, use nitrogen as the carrier gas to inject a mixed solution of ferrocene, ethanol and ethylenediamine into the tubular chemical vapor deposition furnace for reaction, wherein the injection rate of the mixed solution of ferrocene, ethanol and ethylenediamine is 5-10 mL / h, and the flow rate of argon is 400-1000 cm 3 / min.

[0017] Preferably, in step S3, the reaction time is 10 to 40 min.

[0018] A carbon nanotube-silicon nitride nanowire composite material is prepared by the above method; the resistivity of the carbon nanotube-silicon nitride nanowire composite material is 0.64 to 1.24 Ω·cm.

[0019] The application of the above carbon nanotube-silicon nitride nanowire composite material in the field of electronic devices.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] The present invention discloses a preparation method of a carbon nanotube-silicon nitride nanowire composite material:

[0022] First, the method uses silicon nitride nanowires as the skeleton, and in-situ grafts carbon nanotube arrays on their surfaces by chemical vapor deposition. The carbon nanotubes grow vertically on the surface of the silicon nitride nanowires, forming a feather-like carbon nanotube array. As a one-dimensional material with excellent conductivity, the resistance of electrons migrating in its axial channel is extremely small, and an efficient electron channel can be formed. Grafting carbon nanotubes in-situ on the surface of silicon nitride nanowires can establish a conductive bridge across the structural gap between insulating ceramics, constructing an overall continuous electron path to reduce the resistivity. The feather-like carbon nanotubes can construct a highly ordered and continuously conductive carbon network at the nanoscale, enabling electrons to migrate rapidly along the carbon nanotubes and achieving efficient charge transfer across the silicon nitride ceramic interface.

[0023] Second, stable electron channels are formed by cross-linking and multi-point contact between the feather-like carbon nanotubes. In addition, the interface between the carbon nanotubes and the silicon nitride nanowires is tightly combined, effectively reducing the interface resistivity and realizing the transition of silicon nitride nanowires from an insulator to a conductive material, providing technical support for the functional application of silicon nitride ceramic materials in the fields of electronic structures, conductive coatings, micro-nano electrodes, etc.

[0024] In a third aspect, during the growth process of carbon nanotubes, the reaction temperature is 780 - 810 °C. At such high temperatures, ferrocene decomposes to form iron nanoparticles, providing active sites for the growth of carbon nanotubes. Under high-temperature conditions, carbon atoms preferentially arrange along specific crystal planes on the surface of the catalyst. Combining with the surface structure of silicon nitride nanowires, it promotes the growth of carbon nanotubes perpendicular to the substrate, forming a feather-like array. If the temperature is too high, ferrocene decomposes excessively, generating an excessive amount of iron particles. The particle size becomes larger and severe agglomeration occurs, reducing the surface energy of the catalyst, resulting in a decrease in the nucleation density of carbon nanotubes. At the same time, the decomposition rate of the carbon source is too fast, and an excessive amount of carbon atoms are deposited, easily forming disordered carbon deposits or generating thick carbon fiber-like structures, which destroys the morphology of the feather-like ordered array, leading to a loose and disordered structure of the obtained material and losing the feather-like characteristics. If the temperature is too low, ferrocene decomposes insufficiently, resulting in a small amount or too small particle size of the active iron catalyst particles. At the same time, the ethanol of the carbon source cracks insufficiently at low temperatures, restricting the supply of carbon atoms. The nucleation rate of carbon nanotubes is slow and the growth driving force is insufficient, resulting in sparse growth, short length, and disordered arrangement of carbon nanotubes, and unable to form a complete feather-like array.

[0025] In summary, the present invention realizes the in-situ construction of a feather-like carbon nanotube array with directionality and structural continuity on the surface of silicon nitride nanowires through chemical vapor deposition technology, thereby significantly reducing the resistivity and improving the overall electrical conductivity of the material. After testing, the resistivity of the feather-like carbon nanotube-silicon nitride nanowire composite material prepared by the present invention can reach as low as 0.64 Ω·cm, which is lower than the resistivity of silicon nitride-based composite materials in the prior art, thus improving the overall electrical conductivity and demonstrating its potential application value in the fields of electronic devices and the like.

[0026] Furthermore, by controlling the mass ratio of polyazidosilane to ferrocene at (7 - 9):1, optimizing the catalyst distribution and particle size, it promotes the high-density and uniform growth of carbon nanotubes. At the same time, by controlling the volume ratio of polyazidosilane to acetone at 1:(0.5 - 1), adjusting the solution viscosity, and improving the film-forming uniformity and denseness, it provides a good foundation for the preparation of high-quality carbon nanotube-silicon nitride nanowire composite materials.

[0027] Furthermore, in step S1, by standing at room temperature for 5 - 10 days, it can promote the full volatilization of the solvent and the moderate pre-crosslinking of the precursor, improving the film-forming quality and structural stability, and providing a good precursor foundation for the subsequent high-quality formation of silicon nitride nanowires and the growth of carbon nanotubes.

[0028] Furthermore, in step S2, the D ground into powder 50 is 1 - 10 μm, which can effectively increase the specific surface area and film-forming uniformity, promote the continuous growth of silicon nitride nanowires and the stable bonding of subsequent carbon nanotubes, and ensure that the composite material has a dense structure and excellent performance.

[0029] Further, in step S2, during the heat treatment process, the preheating process is achieved by maintaining at 300 - 350 °C for 2 - 3 hours, which can fully remove residual components and stabilize the precursor structure. Then, by maintaining at a high temperature of 1400 - 1500 °C for 3 - 4 hours, deep pyrolysis and the formation of highly crystalline nanowires can be achieved. Finally, cooling with the furnace can effectively ensure that the silicon nitride nanowires have a dense, continuous structure and excellent performance, providing an ideal basis for the efficient growth of carbon nanotubes in the subsequent process.

[0030] Further, in step S3, the mass ratio of ferrocene to ethanol is 1:(90 - 100); the mass ratio of ferrocene to ethylenediamine is 1:(15 - 17), which helps to ensure the full dissolution and uniform dispersion of the catalyst precursor, and promotes the stable growth of carbon nanotubes with a high density, slender structure.

[0031] Further, in step S3, nitrogen is used as the carrier gas to inject the mixed solution of ferrocene, ethanol, and ethylenediamine into the tubular chemical vapor deposition furnace for reaction. The injection rate of the mixed solution of ferrocene, ethanol, and ethylenediamine is 5 - 10 mL / h, and the flow rate of argon is 400 - 1000 cm 3 / min, which can achieve the stable supply and uniform transport of the catalyst and carbon source, promote the continuous and orderly growth of feather-like ultra-long carbon nanotubes, and improve the overall structural integrity and performance of the composite material.

[0032] Further, in step S3, the reaction time is 10 - 40 min, which can make full use of the catalyst activity window to achieve the rapid and continuous growth of carbon nanotubes, avoid catalyst deactivation and by-product deposition, and thus obtain a uniform and dense feather-like carbon nanotube network structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0034] Figure 1 is a scanning electron microscope photograph of the feather-like carbon nanotubes grown on the surface of the silicon nitride nanowires prepared in Example 3 of the present invention;

[0035] Figure 2 is a scanning electron microscope photograph of the feather-like carbon nanotubes grown on the surface of the silicon nitride nanowires prepared in Example 3 of the present invention at another magnification;

[0036] Figure 3 is the resistance diagram of the feather-like carbon nanotubes grown on the surface of the silicon nitride nanowires prepared in Example 3 of the present invention;

[0037] Figure 4 It is a scanning electron microscope photograph of granular carbon nanotubes grown on the surface of silicon nitride nanowires prepared in Comparative Example 1 of the present invention;

[0038] Figure 5 It is a scanning electron microscope photograph of curved carbon nanotubes grown on the surface of silicon nitride nanowires prepared in Comparative Example 2 of the present invention. Detailed implementation manners

[0039] To enable those skilled in the art to understand the characteristics and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meanings understood by those skilled in the art for the present invention. In case of conflict, the definitions in this specification shall prevail.

[0040] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0041] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the ranges (including integers and fractions).

[0042] In this article, unless otherwise specified, the terms "comprising", "including", "containing", "having", or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0043] In this article, for the sake of brevity of description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as within the scope described in this specification.

[0044] The present invention provides a method for preparing a carbon nanotube-silicon nitride nanowire composite material, comprising the following steps:

[0045] S1: After mixing liquid polyazidosilane, acetone, and ferrocene, place them in the air and let them stand at room temperature for 5 to 10 days. The solution naturally cures into a solid state to obtain product A;

[0046] Among them, liquid polyazidosilane is used as the precursor of silicon nitride, acetone is used as the solvent, and ferrocene is used as the catalyst;

[0047] The mass ratio of the polyazidosilane to the ferrocene is (7-9):1; the volume ratio of the polyazidosilane to the acetone is 1:(0.5-1).

[0048] S2: Grind the product A to a powder D 50 with a size of 1-10 μm, take 2-5 grams of the ground powder, and place it between two parallel stacked carbon papers; and place the sample in a horizontal tube furnace. Under an ultra-high purity nitrogen atmosphere, the ground powder is heat-treated. Specifically: first, hold at a temperature of 300-350 °C for 2-3 h for preheating, then raise the temperature to 1400-1500 °C, keep the temperature constant for 3-4 h, cool down to room temperature with the furnace, take out the sample, and peel the silicon nitride nanowire film grown on the carbon paper from the carbon paper to obtain product B; where the flow rate of nitrogen is 60-80 cm 3 / min.

[0049] The carbon paper here can be a U-shaped carbon paper, which can effectively wrap or fix the ground powder and provide support during the heat treatment process.

[0050] S3: Place product B in a tube chemical vapor deposition furnace. Under an argon atmosphere, heat the chemical vapor deposition furnace to 780-810 °C, and then use argon as the carrier gas to inject a mixed solution of ferrocene, ethanol, and ethylenediamine into the tube chemical vapor deposition furnace for reaction for 10-40 min. The injection rate of the mixed solution of ferrocene, ethanol, and ethylenediamine is 5-10 mL / h, and the flow rate of argon is 400-1000 cm 3 / min to obtain the carbon nanotube-silicon nitride nanowire composite. The carbon nanotube-silicon nitride nanowire composite is distributed in a feather shape.

[0051] Among them, the mass ratio of ferrocene to ethanol in the mixed solution of ferrocene, ethanol, and ethylenediamine is 1:(90-100); the mass ratio of ferrocene to ethylenediamine is 1:(15-17).

[0052] In addition, the present invention also discloses a carbon nanotube-silicon nitride nanowire composite prepared by the above method. The resistivity of the carbon nanotube-silicon nitride nanowire composite is 0.64-1.24 Ω·cm.

[0053] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0054] In the following examples, conventional instruments and equipment in the art are used. For the experimental methods without specific conditions indicated in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturers. In the following examples, various raw materials are used. Unless otherwise specified, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0055] Example 1

[0056] A preparation scheme for a feather-like carbon nanotube-silicon nitride nanowire composite material includes the following steps:

[0057] (1) Liquid polyazidosilane is used as the precursor of silicon nitride, ferrocene is used as the catalyst, and acetone is used as the solvent. A homogeneous solution is prepared by mixing polyazidosilane, acetone and ferrocene according to the mass ratio of polyazidosilane to ferrocene of 7.5:1 and the volume ratio of polyazidosilane to acetone of 1:0.8. Then it is left standing in air for 7 days, and the solution naturally solidifies into a solid state to obtain product A.

[0058] (2) Grind product A into a uniform powder in a mortar, and take 4 grams of the ground powder and spread it evenly on the bottom of a U-shaped carbon paper. Then take another U-shaped carbon paper and cover it on the carbon paper with the ground powder spread on it. Put the treated sample into a horizontal tube furnace for heat treatment. The specific operation process is as follows: Introduce ultra-high purity nitrogen into the horizontal tube furnace, and the flow rate of nitrogen is 65 cm 3 / min. First, heat the horizontal tube furnace to 310 °C and keep it at this temperature for 2.2 h. Then raise the temperature to 1420 °C and keep it for 3.2 h. Finally, the system is naturally cooled to room temperature. Take out the sample and peel the silicon nitride nanowire film grown on the upper carbon paper from the carbon paper. The obtained sample is marked as product B.

[0059] (3) Mix ferrocene, absolute ethanol and ethylenediamine evenly, where the mass ratio of ferrocene to absolute ethanol is 1:92 and the mass ratio of ferrocene to ethylenediamine is 1:15.5. Stir evenly to obtain solution C.

[0060] (4) Place product B in a tubular chemical vapor deposition furnace. Under an argon atmosphere, heat the quartz tube to 780 °C. Place solution C in an injection system and inject it into the quartz tube at a rate of 6 mL / h. Adjust the argon flow rate to 600 cm 3 / min, and the growth time is 15 min to obtain a feather-like carbon nanotube-silicon nitride nanowire composite material.

[0061] In this embodiment, feather-like carbon nanotubes are prepared on the surface of silicon nitride nanowires. The carbon nanotubes grow vertically on the surface of the silicon nitride nanowires. The resistance of the feather-like carbon nanotube-silicon nitride nanowire composite is 62 Ω, and the resistivity is 1.24 Ω·cm.

[0062] Example 2

[0063] A preparation scheme for a feather-like carbon nanotube-silicon nitride nanowire composite includes the following steps:

[0064] (1) Use liquid polyazidosilane as the precursor of silicon nitride, ferrocene as the catalyst, and acetone as the solvent. Configure a homogeneous solution by mixing polyazidosilane, acetone, and ferrocene according to the mass ratio of polyazidosilane to ferrocene of 8:1 and the volume ratio of polyazidosilane to acetone of 1:0.7. Then let it stand in the air for 6 days, and the solution naturally cures into a solid state. The obtained sample is marked as product A;

[0065] (2) Grind product A into a homogeneous powder in a mortar, and take 3.5 grams of the ground powder and spread it evenly on the bottom of a U-shaped carbon paper. Then take another U-shaped carbon paper and cover it on the carbon paper with the ground powder spread on it. Put the treated sample into a horizontal tube furnace for heat treatment. The specific operation process is as follows: Pass ultra-high purity nitrogen into the horizontal tube furnace, and the flow rate of nitrogen is 70 cm 3 / min. First, heat the system to 320 °C and keep it at this temperature for 2.4 h. Then raise the temperature to 1440 °C and keep it for 3.3 h. Finally, let the system cool naturally to room temperature. Take out the sample and peel off the silicon nitride nanowire film grown on the upper carbon paper from the carbon paper. The obtained sample is marked as product B;

[0066] (3) Mix ferrocene, absolute ethanol, and ethylenediamine evenly, where the mass ratio of ferrocene to absolute ethanol is 1:94, and the mass ratio of ferrocene to ethylenediamine is 1:16. Stir evenly to obtain solution C.

[0067] (4) Place product B in a tube chemical vapor deposition furnace. Under an argon atmosphere, heat the quartz tube to 790 °C. Place solution C in an injection system and inject it into the quartz tube at a rate of 7 mL / h. Adjust the argon flow rate to 700 cm 3 / min, and the growth time is 20 min to obtain a feather-like carbon nanotube-silicon nitride nanowire composite.

[0068] In this embodiment, feather-like carbon nanotubes are prepared on the surface of silicon nitride nanowires. The carbon nanotubes grow vertically on the surface of the silicon nitride nanowires. The resistance of the feather-like carbon nanotube-silicon nitride nanowire composite is 48 Ω, and the resistivity is 0.96 Ω·cm.

[0069] Example 3

[0070] A preparation scheme for a feather-shaped carbon nanotube - silicon nitride nanowire composite material, comprising the following steps:

[0071] (1) Use liquid polyazidosilane as the precursor of silicon nitride, ferrocene as the catalyst, and acetone as the solvent. Configure a uniform solution by mixing polyazidosilane, acetone, and ferrocene according to the mass ratio of polyazidosilane to ferrocene being 8.5:1 and the volume ratio of polyazidosilane to acetone being 1:0.8. Then let it stand in air for 7 days, and the solution naturally cures into a solid state. The obtained sample is marked as product A;

[0072] (2) Grind product A into a uniform powder in a mortar, and take 4 grams of the ground powder and evenly spread it on the bottom of a U-shaped carbon paper. Then take another U-shaped carbon paper and cover it on the carbon paper with the ground powder spread on it. Put the treated sample into a horizontal tube furnace for heat treatment. The specific operation process is as follows: Pass ultra-high purity nitrogen into the horizontal tube furnace, and the flow rate of nitrogen is 75 cm 3 / min. First, heat the system to 330 °C and maintain it at this temperature for 2.6 h. Then raise the temperature to 1460 °C and maintain it for 3.6 h. Finally, let the system cool naturally to room temperature. Take out the sample and peel off the silicon nitride nanowire film grown on the upper carbon paper from the carbon paper. The obtained sample is marked as product B;

[0073] (3) Mix ferrocene, absolute ethanol, and ethylenediamine evenly, where the mass ratio of ferrocene to absolute ethanol is 1:96 and the mass ratio of ferrocene to ethylenediamine is 1:16.5. Stir evenly to obtain solution C.

[0074] (4) Place product B in a tube chemical vapor deposition furnace. Under an argon atmosphere, heat the quartz tube to 810 °C. Place solution C in an injection system and inject it into the quartz tube at a rate of 8 mL / h. Adjust the argon flow rate to 800 cm 3 / min, and the growth time is 25 min to obtain a feather-shaped carbon nanotube - silicon nitride nanowire composite material.

[0075] Figures 1 to 2 It is a scanning electron microscope photograph of the feather-shaped carbon nanotubes grown on the surface of the silicon nitride nanowires prepared in Example 3 of the present invention at different magnification ratios. As can be seen from the figure, the carbon nanotubes on the surface of the carbon nanotube - silicon nitride nanowire composite material prepared in this example grow vertically and are distributed in a feather-shaped array.

[0076] Figure 3 It is a resistance diagram of the feather-shaped carbon nanotubes grown on the surface of the silicon nitride nanowires prepared in Example 3 of the present invention. As can be seen from the figure, the resistance of the feather-shaped carbon nanotube - silicon nitride nanowire composite material prepared in this example is 32 Ω, and the resistivity is 0.64 Ω·cm.

[0077] Example 4

[0078] A preparation scheme for a feather-like carbon nanotube - silicon nitride nanowire composite material, comprising the following steps:

[0079] (1) Use liquid polyazidosilane as the precursor of silicon nitride, ferrocene as the catalyst, and acetone as the solvent. Configure a homogeneous solution of polyazidosilane, acetone, and ferrocene according to the mass ratio of polyazidosilane to ferrocene of 7:1 and the volume ratio of polyazidosilane to acetone of 1:0.5, and then let it stand in air for 5 days. The solution naturally cures into a solid state, and the obtained sample is marked as product A;

[0080] (2) Grind product A into a uniform powder in a mortar, and take 2 grams of the ground powder and spread it evenly on the bottom of a U-shaped carbon paper. Then take another U-shaped carbon paper and cover it on the carbon paper with the ground powder spread on it. Put the treated sample into a horizontal tube furnace for heat treatment. The specific operation process is as follows: Pass ultra-high purity nitrogen into the horizontal tube furnace, and the flow rate of nitrogen is 60 cm 3 / min. First, heat the system to 300 °C and maintain it at this temperature for 2 h, then raise the temperature to 1400 °C and maintain it for 3 h. Finally, the system naturally cools to room temperature. Take out the sample and peel the silicon nitride nanowire film grown on the upper carbon paper from the carbon paper. The obtained sample is marked as product B;

[0081] (3) Mix ferrocene, absolute ethanol, and ethylenediamine evenly, where the mass ratio of ferrocene to absolute ethanol is 1:90 and the mass ratio of ferrocene to ethylenediamine is 1:15, and stir evenly to obtain solution C.

[0082] (4) Place product B in a tubular chemical vapor deposition furnace, heat the quartz tube to 800 °C under an argon atmosphere, place solution C in an injection system, and inject it into the quartz tube at a rate of 5 mL / h. Adjust the argon flow rate to 400 cm 3 / min, and the growth time is 10 min to obtain a feather-like carbon nanotube - silicon nitride nanowire composite material.

[0083] The resistivity of the feather-like carbon nanotube - silicon nitride nanowire composite material obtained in this example is 1.08 Ω·cm.

[0084] Example 5

[0085] A preparation scheme for a feather-like carbon nanotube - silicon nitride nanowire composite material, comprising the following steps:

[0086] (1) Using liquid polyazidosilane as the precursor of silicon nitride, ferrocene as the catalyst, and acetone as the solvent. Polyazidosilane, acetone, and ferrocene were configured into a homogeneous solution according to the mass ratio of polyazidosilane to ferrocene of 9:1 and the volume ratio of polyazidosilane to acetone of 1:1. Then, it was left standing in air for 10 days, and the solution naturally solidified into a solid state. The obtained sample was marked as Product A;

[0087] (2) Grind Product A into a uniform powder in a mortar, and take 5 grams of the ground powder and spread it evenly on the bottom of a U-shaped carbon paper. Then, take another U-shaped carbon paper and cover it on the carbon paper with the ground powder spread on it. Place the treated sample in a horizontal tube furnace for heat treatment. The specific operation process is as follows: Pass ultra-high purity nitrogen into the horizontal tube furnace, and the flow rate of nitrogen is 80 cm 3 / min. First, heat the system to 350 °C and maintain it at this temperature for 3 h. Then, raise the temperature to 1500 °C and maintain it for 4 h. Finally, the system naturally cools to room temperature. Take out the sample and peel off the silicon nitride nanowire film grown on the upper carbon paper from the carbon paper. The obtained sample was marked as Product B;

[0088] (3) Mix ferrocene, absolute ethanol, and ethylenediamine evenly, where the mass ratio of ferrocene to absolute ethanol is 1:100 and the mass ratio of ferrocene to ethylenediamine is 1:17. Stir evenly to obtain Solution C.

[0089] (4) Place Product B in a tube chemical vapor deposition furnace. Under an argon atmosphere, heat the quartz tube to 850 °C. Place Solution C in an injection system and inject it into the quartz tube at a rate of 10 mL / h. Adjust the argon flow rate to 1000 cm 3 / min, and the growth time is 40 min to obtain a feather-shaped carbon nanotube-silicon nitride nanowire composite.

[0090] The resistivity of the feather-shaped carbon nanotube-silicon nitride nanowire composite obtained in this example is 1.15 Ω·cm.

[0091] Comparative Example 1

[0092] (1) Using liquid polyazidosilane as the precursor of silicon nitride, ferrocene as the catalyst, and acetone as the solvent. Polyazidosilane, acetone, and ferrocene were configured into a homogeneous solution according to the mass ratio of polyazidosilane to ferrocene of 7:1 and the volume ratio of polyazidosilane to acetone of 1:0.5. Then, it was left standing in air for 5 days, and the solution naturally solidified into a solid state. The obtained sample was marked as Product A;

[0093] (2) Grind the product A into a uniform powder in a mortar, take 2 g of the ground powder and spread it evenly on the bottom of the U-shaped carbon paper. Then take another piece of U-shaped carbon paper and cover it on the carbon paper with the ground powder. Put the treated sample into a horizontal tube furnace for heat treatment. The specific operation process is as follows: Pass ultra-high purity nitrogen into the horizontal tube furnace, and the flow rate of nitrogen is 60 cm 3 / min. First, heat the system to 300 °C and keep it at this temperature for 2 h. Then raise the temperature to 1400 °C and keep it for 3 h. Finally, let the system cool naturally to room temperature. Take out the sample and peel off the silicon nitride nanowire film grown on the upper carbon paper from the carbon paper. The obtained sample is marked as product B;

[0094] (3) Mix ferrocene, absolute ethanol and ethylenediamine evenly. The mass ratio of ferrocene to absolute ethanol is 1:90, and the mass ratio of ferrocene to ethylenediamine is 1:15. Stir evenly to obtain solution C.

[0095] (4) Place product B in a tube chemical vapor deposition furnace. Under an argon atmosphere, heat the quartz tube to 750 °C. Place solution C in an injection system and inject it into the quartz tube at a rate of 5 mL / h. Adjust the argon flow rate to 400 cm 3 / min, and the growth time is 10 min to obtain a granular carbon nanotube-silicon nitride nanowire composite material.

[0096] Figure 4 Figure 14 is a scanning electron microscope photograph of the granular carbon nanotubes grown on the surface of the silicon nitride nanowires prepared in Comparative Example 1 of the present invention. As can be seen from the figure, granular carbon nanotubes are prepared on the surface of the silicon nitride nanowires in this comparative example. The resistance of the granular carbon nanotube-silicon nitride nanowire composite material is 392 Ω, and the resistivity is 7.84 Ω·cm. In this comparative example, only granular carbon nanotube structures are grown on the surface of the silicon nitride nanowires, and no feather-like arrays are formed, resulting in a lack of effective connection between the carbon nanotubes, the interruption of the conductive path, and the discontinuity of the overall network, resulting in a decrease in resistivity. In this example, the growth conditions of the carbon nanotubes are not fully regulated, and it is difficult to achieve the feather-like directional growth of the carbon nanotubes on the surface of the silicon nitride nanowires, further verifying the indispensability of each step in the process of the present invention for constructing a high-performance conductive structure.

[0097] Comparative Example 2

[0098] (1) Use liquid polyazidosilane as the precursor of silicon nitride, ferrocene as the catalyst, and acetone as the solvent. Prepare a uniform solution by mixing polyazidosilane, acetone and ferrocene according to the mass ratio of polyazidosilane to ferrocene of 9:1 and the volume ratio of polyazidosilane to acetone of 1:1. Then let it stand in the air for 10 days, and the solution naturally cures into a solid state. The obtained sample is marked as product A;

[0099] (2) Grind the product A into a uniform powder in a mortar, take 5 g of the ground powder and spread it evenly on the bottom of a U-shaped carbon paper. Then take another U-shaped carbon paper and cover it on the carbon paper with the ground powder. Put the treated sample into a horizontal tube furnace for heat treatment. The specific operation process is as follows: Pass ultra-high purity nitrogen into the horizontal tube furnace, and the flow rate of nitrogen is 80 cm 3 / min. First, heat the system to 350 °C and keep it at this temperature for 3 h. Then raise the temperature to 1500 °C and keep it for 4 h. Finally, let the system cool naturally to room temperature. Take out the sample and peel off the silicon nitride nanowire film grown on the upper carbon paper from the carbon paper. The obtained specimen is marked as product B;

[0100] (3) Mix ferrocene, absolute ethanol and ethylenediamine evenly. The mass ratio of ferrocene to absolute ethanol is 1:100, and the mass ratio of ferrocene to ethylenediamine is 1:17. Stir evenly to obtain solution C.

[0101] (4) Place product B in a tube chemical vapor deposition furnace. Under an argon atmosphere, heat the quartz tube to 850 °C. Place solution C in an injection system and inject it into the quartz tube at a rate of 10 mL / h. Adjust the argon flow rate to 1000 cm 3 / min, and the growth time is 40 min to obtain a curved carbon nanotube-silicon nitride nanowire composite material.

[0102] Figure 5 Figure 14 is a scanning electron microscope photograph of the curved carbon nanotubes grown on the surface of the silicon nitride nanowires prepared in Comparative Example 2 of the present invention. As can be seen from the figure, curved carbon nanotubes are prepared on the surface of the silicon nitride nanowires in this comparative example. The resistance of the curved carbon nanotube-silicon nitride nanowire composite material is 234 Ω, and the resistivity is 4.68 Ω·cm. The carbon nanotubes grown on the surface of the silicon nitride nanowires in this comparative example generally show a curved morphology and fail to form a continuous and directionally arranged feather-like array structure. Due to the bending and folding of the carbon nanotubes along the axial direction, the contact area between adjacent tube bodies decreases and the conduction path is not straight, resulting in a significant decrease in the electron transport efficiency and poor construction of the conductive network. In this example, the growth conditions of the carbon nanotubes are overly regulated, and it is difficult to achieve the feather-like directional growth of the carbon nanotubes on the surface of the silicon nitride nanowires, further verifying the indispensability of each step in the process of the present invention for constructing a high-performance conductive structure.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and do not limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a carbon nanotube-silicon nitride nanowire composite material, characterized in that, It includes the following steps: S1: After mixing polyazidosilane, acetone and ferrocene, let it stand at room temperature. After the solution solidifies, product A is obtained; S2: Grind the product A, and place the ground powder between two parallelly stacked carbon papers; then, under a nitrogen atmosphere, perform heat treatment on the ground powder to obtain product B; S3: Place product B in a tube-type chemical vapor deposition furnace, heat the system to 780 - 810 °C under an argon atmosphere, and then use argon as the carrier gas to inject a mixed solution of ferrocene, ethanol and ethylenediamine into the tube-type chemical vapor deposition furnace for reaction to obtain the carbon nanotube-silicon nitride nanowire composite material.

2. The preparation method of a carbon nanotube-silicon nitride nanowire composite material according to claim 1, wherein The mass ratio of the polyazidosilane to the ferrocene is (7 - 9):1; the volume ratio of the polyazidosilane to the acetone is 1:(0.5 - 1).

3. The preparation method of a carbon nanotube-silicon nitride nanowire composite material according to claim 1, wherein In step S1, let it stand at room temperature for 5 - 10 days.

4. The preparation method of a carbon nanotube - silicon nitride nanowire composite material according to claim 1, characterized in that, In step S2, D ground into powder 50 is 1 to 10 μm.

5. The preparation method of a carbon nanotube-silicon nitride nanowire composite material according to claim 1, characterized in that, In step S2, the heat treatment process is specifically: first maintain at a temperature of 300 - 350 °C for 2 - 3 h, then raise the temperature to 1400 - 1500 °C, keep the temperature constant for 3 - 4 h, and cool to room temperature with the furnace.

6. The preparation method of a carbon nanotube-silicon nitride nanowire composite material according to claim 1, characterized in that, In step S3, the mass ratio of the ferrocene to the ethanol is 1:(90 - 100); the mass ratio of the ferrocene to the ethylenediamine is 1:(15 - 17).

7. The preparation method of a carbon nanotube-silicon nitride nanowire composite material according to claim 1, characterized in that, In step S3, a mixed solution of ferrocene, ethanol, and ethylenediamine is injected into a tubular chemical vapor deposition furnace using nitrogen as the carrier gas for reaction. The injection rate of the mixed solution of ferrocene, ethanol, and ethylenediamine is 5-10 mL / h, and the flow rate of argon is 400-1000 cm 3 / min.

8. The preparation method of a carbon nanotube - silicon nitride nanowire composite material according to claim 1, characterized in that, In step S3, the reaction time is 10 - 40 min.

9. A carbon nanotube - silicon nitride nanowire composite material, characterized in that, It is obtained by the method described in any one of claims 1 - 8; the resistivity of the carbon nanotube-silicon nitride nanowire composite material is 0.64 - 1.24 Ω·cm.

10. Application of the carbon nanotube-silicon nitride nanowire composite material described in claim 9 in the field of electronic devices.

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