A method for preparing tungsten carbide nanowires and tungsten carbide nanowires

Abstract

This application relates to a method for preparing tungsten carbide nanowires and the tungsten carbide nanowires themselves. The method for preparing tungsten carbide nanowires comprises the following steps: (1) separating, dispersing, structurally activating, and drying a plant carbon source in an alcohol solvent to obtain an activated carbon source; (2) dissolving the activated carbon source and catalyst in an alcohol solvent, adding a tungsten source, homogenizing, and drying to obtain a precursor mixture; (3) mechanically activating the precursor mixture; and (4) reducing and carbonizing the activated precursor mixture. The method of this application uses a plant carbon source to obtain a stable precursor, which not only significantly reduces raw material and equipment costs but also simplifies the preparation process and improves synthesis efficiency. The tungsten carbide nanowires of this application have uniform size and excellent mechanical properties.

Description

Technical Field

[0001] This application relates to the technical field of tungsten carbide nanoproduct preparation, and particularly to a method for preparing tungsten carbide nanowires and tungsten carbide nanowires. Background Technology

[0002] Tungsten carbide nanowires possess excellent field emission properties, extremely high resolution, and good oxidation resistance, making them suitable for use in scanning tunneling electron microscopes and field emission electronic devices. They also exhibit higher mechanical properties compared to bulk tungsten carbide, allowing them to be used to strengthen cemented carbides and in cemented carbide micro-drills for printed circuit boards. Therefore, tungsten carbide nanowires have significant application prospects.

[0003] However, the preparation of tungsten carbide nanowires currently faces numerous challenges. For example, existing methods mostly utilize high-cost raw materials, require sophisticated equipment, endure harsh preparation conditions, involve complex processes, suffer from low yields, and exhibit poor process stability. These methods are currently limited to basic research and small-batch production, making large-scale production and application difficult. Furthermore, some tungsten carbide nanowire preparation methods require high-temperature carbonization, often using a mixture of hydrogen and methane as the carbon source, which makes the process relatively dangerous. On the other hand, synthesis methods that do not use hydrogen and methane as carbon sources produce tungsten carbide nanomaterials with complex tungsten and carbon compound compositions, resulting in unsatisfactory product purity.

[0004] Therefore, the industry has always needed a method for preparing tungsten carbide nanowires that has low raw material and equipment costs, simple process, high process stability and repeatability, as well as tungsten carbide nanowires with uniform size, high purity and excellent mechanical properties. Summary of the Invention

[0005] The method described in this application successfully meets the aforementioned needs. It successfully solves the challenge of achieving low-cost, short-process, and efficient synthesis of tungsten carbide nanowires. This paper provides a method for preparing tungsten carbide nanowire materials using plant carbon sources, resulting in tungsten carbide nanowire materials with uniform size and excellent mechanical properties.

[0006] The first aspect of this application provides a method for preparing tungsten carbide nanowires, comprising the following steps: (1) separating, dispersing, structurally activating and drying a plant carbon source in an alcohol solvent to obtain an activated carbon source; (2) dissolving the activated carbon source and catalyst in the alcohol solvent, adding a tungsten source, homogenizing and drying to obtain a precursor mixture; (3) mechanically activating the precursor mixture; and (4) reducing and carbonizing the activated precursor mixture.

[0007] The second aspect of this application provides tungsten carbide nanowires with uniform size, high purity, and excellent mechanical properties. Specifically, the tungsten carbide nanowires described herein have a diameter of 50–110 nm, a radial dimension difference of 3–8 nm, a length of 20–100 μm, an aspect ratio of 200–1200, and a tungsten carbide phase purity ≥98%.

[0008] In the method of this application, plant carbon sources are used as raw materials. The plant carbon sources used in this paper have the advantages of being safe and non-toxic, abundant, low-cost, relatively stable, and easy to activate. Moreover, through a combination of specific raw material treatment, structural activation, mechanical activation, and reductive carbonization steps, the synthesis process of nanowires is stabilized, the production process is simplified, and production costs are saved.

[0009] Even more advantageously, the method of this application does not require the use of hydrogen and methane, which makes the production process safer.

[0010] The inventors also discovered that, compared to other transition metal carbides, tungsten carbide grains grow very easily at high temperatures and are difficult to control, leading to the destruction of the nanowire structure and the formation of particulate nanomaterials. However, the method of this invention can stably obtain tungsten carbide with a one-dimensional nanowire structure.

[0011] Moreover, the tungsten carbide nanowires obtained by the method of this application have advantages such as uniform size, high purity, and excellent mechanical properties.

[0012] The above description of the invention is not intended to depict every disclosed embodiment or implementation of the invention. Illustrative embodiments are illustrated in more detail in the following description. Detailed Implementation

[0013] definition

[0014] In this document, unless otherwise stated, the terms "a," "this," "at least one," and "one or more," as well as instances where no quantifier is used, are used interchangeably. Thus, for example, a composition containing "a" additive can be interpreted as meaning that the composition contains "one or more" additives. Unless otherwise stated herein, the use of the singular form is also intended to include the plural form.

[0015] When a composition is described as including or containing specific components, it is anticipated that optional components not covered in this application are not excluded from the composition, and that the composition may be constituted or composed of the components involved. Similarly, when a method is described as including or containing specific process steps, it is anticipated that optional process steps not covered in this application are not excluded from the method, and that the method may be constituted or composed of the process steps involved.

[0016] For simplicity, this document only explicitly discloses some numerical ranges. However, it should be understood that any range formed by combining any lower limit with any upper limit is included in the scope explicitly disclosed in this application; similarly, any range formed by combining any lower limit with other lower limits is also included in the scope explicitly disclosed in this application, and so on.

[0017] In the context of describing a composition as free from a certain ingredient, the term "free from" means that the composition does not contain that ingredient intentionally added. Given the complexity of the specific composition of each component in actual formulation, the phrase "free from a certain ingredient" can be understood as the composition containing less than 1% by weight of that ingredient based on the total weight of the composition, more preferably less than 0.5% by weight, even more preferably less than 0.2% by weight, and most preferably less than 0.1% by weight. Similarly, in the context of describing a method as free from a certain step, the term "free from" means that the method does not contain that step intentionally or consciously employed.

[0018] The terms "preferred" and "ideally" refer to embodiments of this application that provide certain benefits in certain circumstances. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application.

[0019] After analyzing existing methods for preparing tungsten carbide nanowires, the inventors conducted bold and in-depth research on these methods and discovered that the method described in this paper can solve one or more problems in existing methods.

[0020] Specifically, the method of this application includes the following steps: (1) separating, dispersing, activating and drying the carbon source components of the plant carbon source in an alcohol solvent to obtain an activated carbon source; (2) dissolving the activated carbon source and catalyst in the alcohol solvent, adding a tungsten source, homogenizing and drying to obtain a precursor mixture; (3) mechanically activating the precursor mixture; and (4) reducing and carbonizing the activated precursor mixture.

[0021] The alcohol solvent in step (1) can be an alcohol solvent capable of separating, dispersing, and structurally activating the carbon source components in the plant carbon source. Plant carbon sources typically contain some bio-oil compounds (such as hexane, acetaldehyde, acetone, hydroxyacetaldehyde, hydroxyacetone, L-glucan, etc.) and some substances that generate gas at high temperatures. The inventors found that under high-temperature calcination, these oil compounds, when used as carbon sources, easily affect the synthesis of nanowires, thereby affecting the size uniformity and quality of tungsten carbide nanowires. By mixing the alcohol solvent with the plant carbon source, the bio-oil compounds can be extracted from the plant fibers, and this is beneficial for the uniform dispersion of the plant fibers and reduces entanglement.

[0022] In some embodiments, the alcohol solvent is selected from one or more of methanol, anhydrous ethanol, propanol, ethylene glycol, and butanol. Preferably, the alcohol solvent is selected from one or more of methanol, anhydrous ethanol, and ethylene glycol.

[0023] In some preferred embodiments, the alcohol solvent can further activate the fibrous structure of the plant carbon source. Preferably, heating the mixture of plant carbon source and alcohol solvent under ultrasonic treatment is beneficial for further improving structural activation. In some embodiments, the structural activation treatment temperature is 80–110°C, preferably 83–106°C, and the treatment time is 30–70 minutes, preferably 40–65 minutes. As an example, the ultrasonic power can be 50–120 kHz, preferably 60–100 kHz. In some embodiments, the drying temperature is 60–75°C.

[0024] In some embodiments, the plant carbon source is selected from flax stalks, jute stalks, or bamboo stalks, processed into powder, or any combination thereof. The inventors have discovered that the above-mentioned plant carbon sources are not only renewable resources and abundant, but also contain relatively stable and easily activated carbon components, which helps to simplify the preparation process of tungsten carbide nanowires and stabilize the synthesis process of nanowires.

[0025] In some embodiments, the average particle size of the plant carbon source is 30–100 micrometers, preferably 36–65 micrometers.

[0026] Using step (1) described in this paper is not only beneficial for separating the activated carbon component to prepare for subsequent tungsten oxide reduction carbonization, but also beneficial for maintaining the size uniformity of tungsten carbide nanowires during the synthesis process.

[0027] In step (2), the activated carbon source and catalyst are dissolved in an alcohol solvent. In some embodiments, the catalyst is a mixture of ferric nitrate, nickel nitrate, and sodium fluoride. Preferably, the catalyst comprises, or consists of, ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. In some embodiments, the mass ratio of the catalyst (ferric nitrate, nickel nitrate, and sodium fluoride) to the tungsten source is (0.15–0.3):(0.06–0.16):(0.05–0.15):1, preferably (0.18–0.26):(0.08–0.14):(0.06–0.12):1.

[0028] After the catalyst is dissolved, a tungsten source is added, homogenized, and dried to obtain a precursor mixture. Preferably, tungsten oxide is used as the tungsten source. In some embodiments, the tungsten source is tungsten oxide powder with an average particle size of 0.5–3 micrometers, preferably 0.8–1.7 micrometers. In some embodiments, the tungsten source is represented by WOx, where x = 2.1–3.0, preferably 2.25–3, for example 2.4, 2.6, 2.6, 2.7, and 2.8. In some embodiments, the tungsten source is added after the catalyst has completely dissolved. This feeding sequence is more conducive to the catalyst's catalytic effect on the reduction carbonization reaction, reduces defects on the surface of tungsten carbide nanowires, and thus reduces the radial size difference of the tungsten carbide nanowires.

[0029] In some embodiments, the mass ratio of plant carbon source to tungsten source is 2.0:1 to 5.0:1, preferably 2.3:1 to 2.7:1.

[0030] Preferably, the catalyst dissolution in step (2) is carried out at the same temperature as the temperature used for structural activation in step (1). Such a temperature makes it easier for the carbon source components to remain in an activated state during the catalyst dissolution process, thereby allowing the catalyst to combine with more activated carbon source components.

[0031] The inventors discovered that using the mass ratio and dissolution temperature of the catalyst, tungsten source, plant carbon source, and tungsten source described above is beneficial for subsequent reduction and carbonization, while maintaining the high purity of the tungsten carbide nanowires.

[0032] In step (2), the mixture is dried to obtain a precursor mixture. Drying can be performed using methods commonly used in the art, such as natural air drying, vacuum drying, heat drying, inert gas purging, etc. Preferably, heat drying and / or vacuum drying are used. In some embodiments, drying is performed at 65–85°C, preferably 68–79°C.

[0033] In step (3), the precursor mixture is mechanically activated. Preferably, the mechanical activation treatment is performed by ball milling. In some embodiments, agate or zirconium dioxide is selected as the grinding medium. Preferably, the ball-to-material ratio is 3:1 to 10:1, more preferably 4.5:1 to 5.2:1. The ball mill speed can be adjusted appropriately. For example, the ball mill speed can be 140 to 220 rpm. The inventors have found that after separating, dispersing, and structurally activating the carbon source components using an alcohol solvent, then dissolving the catalyst and tungsten source and drying them, followed by mechanical activation of the precursor mixture, this design allows for more uniform dispersion of the components in the precursor mixture, while simultaneously achieving synergistic activation of the tungsten source and carbon source, resulting in an activated precursor mixture.

[0034] In step (4), the activated precursor mixture is reduced and carbonized. Preferably, a two-step reduction-carbonization method is used. This two-step reduction-carbonization follows the theory of reaction thermodynamics and kinetics, allowing the reduction-carbonization process to be completed stepwise in the same space, ensuring the controllability of the growth environment and reaction process of tungsten carbide nanowires. In some embodiments, the activated precursor mixture is heated to 600–850°C, preferably 680–760°C, and held for 60–120 minutes, preferably 75–86 minutes, and then the temperature is further increased to 1000–1300°C, preferably 1100–1230°C, and held for 20–60 minutes, preferably 30–40 minutes.

[0035] Preferably, the reduction carbonization is carried out in an inert atmosphere. For example, the reduction carbonization is carried out in an argon atmosphere. It is worth noting that in the method described herein, there is no need to introduce additional reducing gases (e.g., hydrogen, methane, acetylene, etc.), which reduces the risk of combustion and explosion and improves the safety of the production process.

[0036] In some embodiments, the method of the present invention further includes sieving the product after step (4).

[0037] As can be seen from the above, the method of the present invention can benefit from relatively relaxed process parameters, reduce the stringent requirements on equipment and operation processes, and is simple and easy to operate, making it more conducive to industrial applications.

[0038] The method described in this paper yields tungsten carbide nanowires with uniform size, high purity, and excellent mechanical properties. Notably, the tungsten carbide nanopowder prepared in this application possesses a nanowire structure with a relatively long aspect ratio.

[0039] The tungsten carbide nanowires described herein have a diameter of 50–110 nm, a radial dimension difference of 3–8 nm, a length of 20–100 μm, an aspect ratio of 200–1200, and a tungsten carbide phase purity ≥98%. In some embodiments, the diameter of the tungsten carbide nanowires is 56–104 nm, preferably 65–102 nm, for example 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, or 95 nm. In some embodiments, the radial dimension difference of the tungsten carbide nanowires is 3–8 nm, for example 3.5 nm, 4 nm, 5 nm, 6 nm, or 7 nm. In some embodiments, the length of the tungsten carbide nanowires is about 24–85 μm, for example about 30 μm, 40 μm, 50 μm, 60 μm, or 70 μm. In some embodiments, the aspect ratio of the tungsten carbide nanowires is about 210 to 1100, for example, 220, 225, 250, 300, 400, 500, 600, 700, and 900. In some embodiments, the tungsten carbide phase purity of the tungsten carbide nanowires is ≥98.2%, for example, 98.5%, 98.8%, 99%, 99.2%, and 99.5%.

[0040] The tungsten carbide nanowires prepared by the method described herein also possess excellent mechanical properties. In some embodiments, the tungsten carbide nanowires have a flexural modulus of 740–770 GPa and a room temperature hardness of 20–25 GPa at room temperature. Preferably, the tungsten carbide nanowires have a flexural modulus of 742–761 GPa and a room temperature hardness of 21–23 GPa at room temperature. For example, the tungsten carbide nanowires have a flexural modulus of 745 GPa, 750, or 760 GPa at room temperature. For example, the room temperature hardness of the tungsten carbide nanowires is 22 GPa.

[0041] The method described herein successfully synthesizes tungsten carbide with a one-dimensional nanowire structure that exhibits uniform size, high purity, and excellent mechanical properties by utilizing a safe, non-toxic, abundant, low-cost, relatively stable, and easily activated plant carbon source through a combination of specific raw material processing, structural activation, mechanical activation, and reductive carbonization steps. Furthermore, the preparation method of this invention offers advantages such as high precision in controlling the microstructure, strong process stability, and high repeatability, enabling the efficient preparation of tungsten carbide nanowires.

[0042] As an example, this article also specifically provides a method for preparing tungsten carbide nanowires, including the following steps:

[0043] a) Select tungsten oxide (WOx; where x = 2.25–3) powder with an average particle size of 0.8–1.7 μm as the tungsten source, and select one of the following as the natural plant carbon source: powder made from flax stalks, jute stalks, or bamboo stalks, with an average particle size of 36–65 μm. The catalyst is selected from ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, weigh the natural plant carbon source powder and the catalyst at a mass ratio of (2.3–2.7):1 and (0.18–0.26):(0.08–0.14):(0.06–0.12):1. The alcohol solvent is selected from methanol, anhydrous ethanol, or ethylene glycol. First, the carbon source powder is subjected to component separation and structural activation treatment under heating and ultrasonic conditions. The structural activation treatment temperature and time are 80-110℃ and 30-70 minutes, respectively, and the ultrasonic power is 60-100 kHz. After drying, the activated carbon source is obtained. Then, the activated carbon source and catalyst are stirred and dissolved at the same temperature. Finally, tungsten oxide powder is added and stirred and dried at 68-79℃ to obtain a precursor mixture.

[0044] b) The precursor mixture was mechanically activated by ball milling, using agate or zirconium dioxide grinding media with a ball-to-material ratio of (4.5–5.2):1 and a ball mill speed of 140–220 rpm. The mixture was then placed in an argon atmosphere furnace to complete the two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 680–760℃ and held for 75–86 minutes, then the temperature was raised to 1100–1230℃ and held for 30–40 minutes. The mixture was then cooled with the furnace, and finally the product was sieved to obtain tungsten carbide nanowire materials.

[0045] Unless otherwise stated, the various features and corresponding preferred methods described herein can be combined.

[0046] Example

[0047] The disclosure of this application is described in more detail through the following examples. These examples are merely illustrative and are not limited to these specific examples. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Moreover, all reagents used in the examples are commercially available and ready to use without further processing. Those skilled in the art can readily obtain or prepare the raw materials used in the examples. Unless otherwise specified, all materials used in the examples are of analytical grade.

[0048] Test methods

[0049] Particle size: The average particle size of the material is obtained by statistically analyzing the maximum radial dimensions of more than 300 materials (e.g., plant carbon sources, tungsten sources) using scanning electron microscopy and calculating the average value.

[0050] Radial size difference: Using scanning electron microscopy, the difference between the maximum and minimum radial values ​​of more than 300 nanowires was statistically analyzed, and the radial size difference of the nanowires was obtained by calculating the average of these differences.

[0051] Length: The lengths of more than 300 nanowires were counted using scanning electron microscopy, and the average length of the nanowires was calculated.

[0052] Aspect ratio: The length and diameter of more than 300 nanowires were statistically analyzed using a scanning electron microscope. The aspect ratio was calculated and the average value was used to obtain the aspect ratio of the nanowire.

[0053] Tungsten carbide purity: Oxygen and carbon content were measured using an oxygen-nitrogen analyzer and a carbon-sulfur analyzer, and the content and purity of the WC phase were quantitatively measured using X-ray photoelectron spectroscopy (XPS).

[0054] Scanning electron microscope: Scios1 (Thermo Fisher Scientific, USA), 20kV, WD = 9.7mm.

[0055] Experiment 1

[0056] Tungsten oxide (WOx; where x = 2.4) powder with an average particle size of 0.8 μm was selected as the tungsten source. Flax stalk powder with an average particle size of 45 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, flax stalk powder and catalyst were weighed at a mass ratio of 2.4:1 and 0.19:0.11:0.07:1, respectively. Methanol was selected as the solvent. The flax stalk powder was subjected to component separation, dispersion, and structural activation treatment with methanol under heating and ultrasonic conditions. The treatment temperature and time were 96℃ and 43 minutes, respectively, with an ultrasonic power of 70 kHz. The powder was then dried to obtain the activated carbon source. Subsequently, the activated carbon source and catalyst were stirred and dissolved at the same temperature. Tungsten oxide powder was added, homogenized, and stirred and dried at 69℃ to obtain the precursor mixture.

[0057] The precursor mixture was mechanically activated using ball milling with agate grinding media at a ball-to-material ratio of 4.6:1 and a mill speed of 160 rpm. The mixture was then placed in an argon atmosphere furnace for a two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 680℃ and held for 75 minutes, then further increased to 1100℃ and held for 30 minutes, followed by furnace cooling. Finally, the product was sieved to obtain tungsten carbide nanowire materials.

[0058] Experiment 2

[0059] Tungsten oxide (WOx; where x = 2.5) powder with an average particle size of 0.9 μm was selected as the tungsten source, and jute stalk powder with an average particle size of 65 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, jute stalk powder and catalyst were weighed at a mass ratio of 2.5:1 and 0.21:0.09:0.07:1, respectively. Anhydrous ethanol was used as the solvent. First, the jute stalk powder underwent component separation and chemical activation treatment under heating and ultrasonic conditions. The treatment temperature and time were 94℃ and 54 minutes, respectively, with an ultrasonic power of 80 kHz. After drying, the activated carbon source was obtained. Subsequently, the activated carbon source and catalyst were stirred and dissolved at the same temperature. Finally, tungsten oxide powder was added and stirred and dried at 79℃ to obtain the precursor mixture.

[0060] The precursor mixture was mechanically activated by ball milling with zirconium dioxide as the grinding media at a ball-to-material ratio of 5.1:1 and a milling speed of 220 rpm. The mixture was then placed in an argon atmosphere furnace for a two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 720℃ and held for 82 minutes, then raised to 1130℃ and held for 35 minutes. The mixture was then cooled with the furnace, and finally the product was sieved to obtain tungsten carbide nanowire materials.

[0061] Experiment 3

[0062] Tungsten oxide (WOx; where x = 2.25) powder with an average particle size of 1.1 μm was selected as the tungsten source, and bamboo powder with an average particle size of 36–65 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, bamboo powder and catalyst were weighed at a mass ratio of 2.5:1 and 0.23:0.12:0.12:1, respectively. Methanol was used as the solvent. First, the bamboo powder underwent component separation and chemical activation treatment under heating and ultrasonic conditions. The treatment temperature and time were 106℃ and 40 minutes, respectively, with an ultrasonic power of 100 kHz. After drying, the activated carbon source was obtained. Subsequently, the activated carbon source and catalyst were stirred and dissolved at the same temperature. Finally, tungsten oxide powder was added and stirred and dried at 68℃ to obtain the precursor mixture.

[0063] The precursor mixture was mechanically activated by ball milling with zirconium dioxide as the grinding media at a ball-to-material ratio of 5.1:1 and a milling speed of 190 rpm. The mixture was then placed in an argon atmosphere furnace to complete a two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 760℃ and held for 86 minutes, then raised to 1100℃ and held for 36 minutes. The mixture was then cooled with the furnace, and finally the product was sieved to obtain tungsten carbide nanowire materials.

[0064] Experiment 4

[0065] Tungsten oxide (WOx; where x = 3) powder with an average particle size of 1.5 μm was selected as the tungsten source, and flax stalk powder with an average particle size of 55 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Using the tungsten source as a reference, flax stalk powder and catalyst were weighed at a mass ratio of 2.4:1 and 0.25:0.14:0.06:1, respectively. Ethylene glycol was used as the solvent. First, the flax stalk powder underwent component separation and chemical activation treatment under heating and ultrasonic conditions. The treatment temperature and time were 106℃ and 65 minutes, respectively, with an ultrasonic power of 80 kHz. Subsequently, the catalyst was stirred and dissolved at the same temperature. Finally, tungsten oxide powder was added and stirred and dried at 74℃ to obtain the precursor mixture.

[0066] The precursor mixture was mechanically activated by ball milling with zirconium dioxide as the grinding media at a ball-to-material ratio of 4.8:1 and a milling speed of 220 rpm. The mixture was then placed in an argon atmosphere furnace to complete a two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 700℃ and held for 75 minutes, then raised to 1230℃ and held for 35 minutes. The mixture was then cooled with the furnace, and finally the product was sieved to obtain tungsten carbide nanowire materials.

[0067] Experiment 5

[0068] Tungsten oxide (WOx; where x = 2.8) powder with an average particle size of 1.7 μm was selected as the tungsten source, and jute stalk powder with an average particle size of 45 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, jute stalk powder and catalyst were weighed at a mass ratio of 2.6:1 and 0.2:0.1:0.08:1, respectively. Ethylene glycol was selected as the solvent. First, the jute stalk powder underwent component separation and chemical activation treatment under heating and ultrasonic conditions. The treatment temperature and time were 110℃ and 54 minutes, respectively, with an ultrasonic power of 90 kHz. Subsequently, the catalyst was stirred and dissolved at the same temperature. Finally, tungsten oxide powder was added and stirred and dried at 69℃ to obtain the precursor mixture.

[0069] The precursor mixture was mechanically activated by ball milling with agate grinding media at a ball-to-material ratio of 4.7:1 and a mill speed of 190 rpm. The mixture was then placed in an argon atmosphere furnace for a two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 700℃ and held for 75 minutes, then raised to 1130℃ and held for 37 minutes. The mixture was then cooled with the furnace, and finally the product was sieved to obtain tungsten carbide nanowire materials.

[0070] Experiment 6

[0071] Tungsten oxide (WOx; where x = 2.6) powder with an average particle size of 0.9 μm was selected as the tungsten source, and bamboo powder with an average particle size of 47 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, bamboo powder and catalyst were weighed at a mass ratio of 2.4:1 and 0.21:0.11:0.09:1, respectively. Methanol was selected as the solvent. First, the bamboo powder underwent component separation and chemical activation treatment under heating and ultrasonic conditions. The treatment temperature and time were 96℃ and 49 minutes, respectively, with an ultrasonic power of 60 kHz. Subsequently, the catalyst was stirred and dissolved at the same temperature. Finally, tungsten oxide powder was added and stirred and dried at 72℃ to obtain the precursor mixture.

[0072] The precursor mixture was mechanically activated by ball milling with zirconium dioxide as the grinding media at a ball-to-material ratio of 4.7:1 and a milling speed of 220 rpm. The mixture was then placed in an argon atmosphere furnace to complete a two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 760℃ and held for 75 minutes, then raised to 1200℃ and held for 40 minutes. The mixture was then cooled with the furnace, and finally the product was sieved to obtain tungsten carbide nanowire materials.

[0073] Experiment 7

[0074] Tungsten oxide (WOx; where x = 2.7) powder with an average particle size of 1.3 μm was selected as the tungsten source, and jute stalk powder with an average particle size of 44 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, jute stalk powder and catalyst were weighed at a mass ratio of 2.7:1 and 0.24:0.13:0.12:1, respectively. Anhydrous ethanol was used as the solvent. First, the jute stalk powder underwent component separation and chemical activation treatment under heating and ultrasonic conditions. The treatment temperature and time were 93℃ and 43 minutes, respectively, with an ultrasonic power of 80 kHz. Subsequently, the catalyst was stirred and dissolved at the same temperature. Finally, tungsten oxide powder was added and stirred and dried at 75℃ to obtain the precursor mixture.

[0075] The precursor mixture was mechanically activated by ball milling with zirconium dioxide as the grinding media. The ball-to-material ratio was 4.5:1, and the ball mill speed was 170 rpm. The mixture was then placed in an argon atmosphere furnace to complete the two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 760℃ and held for 78 minutes, then raised to 1130℃ and held for 34 minutes. The mixture was then cooled with the furnace. Finally, the product was sieved to obtain tungsten carbide nanowire materials.

[0076] Experiment 8

[0077] Tungsten oxide (WOx; where x = 2.6) powder with an average particle size of 1 μm was selected as the tungsten source, and bamboo powder with an average particle size of 58 μm was selected as the natural plant carbon source. The catalysts used were ferric nitrate, nickel nitrate, and sodium fluoride with a purity of 99.95%. Based on the tungsten source, bamboo powder and catalyst were weighed at a mass ratio of 2.5:1 and 0.23:0.1:0.1:1, respectively. Ethylene glycol was selected as the solvent. First, the bamboo powder underwent component separation and chemical activation treatment under heating and ultrasonic conditions. The treatment temperature and time were 96℃ and 56 minutes, respectively, with an ultrasonic power of 70 kHz. Subsequently, the catalyst was stirred and dissolved at the same temperature. Finally, tungsten oxide powder was added and stirred and dried at 79℃ to obtain the precursor mixture.

[0078] The precursor mixture was mechanically activated by ball milling with zirconium dioxide as the grinding media at a ball-to-material ratio of 4.6:1 and a milling speed of 220 rpm. The mixture was then placed in an argon atmosphere furnace for a two-step reduction and carbonization process. Specifically, the furnace temperature was first raised to 690℃ and held for 76 minutes, then raised to 1180℃ and held for 38 minutes. The mixture was then cooled with the furnace, and finally the product was sieved to obtain tungsten carbide nanowire materials.

[0079] Comparative Experiment 1

[0080] Experiment 1 was repeated, but tungsten oxide (WOx; where x = 1.9) powder was used as the tungsten source.

[0081] Comparative Experiment 2

[0082] Experiment 1 was repeated, but tungsten oxide (WOx; where x = 5.1) powder was used as the tungsten source.

[0083] Comparative Experiment 3

[0084] Experiment 1 was repeated, but the mass ratio of natural plant carbon source to tungsten source was 1.5.

[0085] Comparative Experiment 4

[0086] Experiment 1 was repeated, but the activation temperature was 130℃.

[0087] Comparative Experiment 5

[0088] Experiment 1 was repeated, but the second step of reduction and carbonization was performed at a temperature of 1400℃.

[0089] Comparative Experiment 6

[0090] Experiment 1 was repeated, but the second step of reduction and carbonization was performed at a temperature of 950°C.

[0091] The microstructure and performance parameters of tungsten carbide nanowires prepared in Experiments 1-8 and the comparative experiment are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] Table 1 shows that the tungsten carbide nanowires prepared by the method described in this paper exhibit uniform dimensions and excellent mechanical properties. Specifically, the tungsten carbide nanowires have a diameter of 50–110 nm, a radial dimensional error of 3–8 nm, a length of 20–100 μm, an aspect ratio of 200–1200, and a tungsten carbide phase purity ≥98%. Furthermore, the tungsten carbide nanowires have a flexural modulus of 740–770 GPa and a room temperature hardness of 20–25 GPa.

[0096] The specification of this application lists various optional materials for the components. However, those skilled in the art should understand that the list of components is neither restrictive nor exhaustive. Various components can be replaced by equivalent materials not mentioned in this specification while still achieving the purpose of this application. Specific examples mentioned in the specification are merely for illustrative purposes and not intended to limit the scope of this application.

[0097] Although this application has been described with reference to numerous embodiments and examples, it will be readily apparent to those skilled in the art that modifications can be made to this application without departing from the principles disclosed in the foregoing specification. For example, combining multiple features or preferred embodiments described herein without departing from the principles disclosed in the foregoing specification should be understood as part of the content described herein. Such modifications are considered to be included in the following claims unless expressly specified otherwise. Accordingly, the embodiments detailed herein are merely exemplary and not intended to limit the scope of this application, which is the full scope of the appended claims and any and all equivalents.

Claims

1. A method for preparing tungsten carbide nanowires, comprising the following steps: (1) The plant carbon source is subjected to carbon source component separation, dispersion, structural activation and drying in an alcohol solvent to obtain an activated carbon source. The structural activation treatment temperature is 80~110℃. (2) Dissolve the activated carbon source and catalyst in the alcohol solvent, add a tungsten source, homogenize and dry to obtain a precursor mixture, wherein the tungsten source is WO3. x This indicates that x = 2.1~3.0, and the mass ratio of the plant carbon source to the tungsten source is 2.0:1~5.0:

1. (3) The precursor mixture is mechanically activated, and (4) Reduce and carbonize the activated precursor mixture by heating the activated precursor mixture to 600~850℃ and holding it for 60~120 minutes, and then continuing to heat it to 1000~1300℃ and holding it for 20~60 minutes.

2. The preparation method according to claim 1, characterized in that, The alcohol solvent is selected from one or more of methanol, anhydrous ethanol, propanol, ethylene glycol, and butanol.

3. The preparation method according to claim 1, characterized in that, The plant carbon source is selected from flax stalks, jute stalks, or bamboo stalks made into powder, or any combination thereof, and / or The average particle size of the plant carbon source is 30-100 micrometers.

4. The preparation method according to claim 1, characterized in that, The catalyst is a mixture of ferric nitrate, nickel nitrate, and sodium fluoride.

5. The preparation method according to claim 1, characterized in that, The tungsten source is tungsten oxide powder with an average particle size of 0.5 to 3 micrometers.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the plant carbon source to the tungsten source is 2.3:1 to 2.7:

1.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The activation temperature of the structure is 83~106℃, and the treatment time is 30~70 minutes; the drying temperature is 60~75℃.

8. The preparation method according to any one of claims 1 to 6, characterized in that, The mechanical activation is carried out by ball milling, with a ball-to-material ratio of 3:1 to 10:

1.

9. The preparation method according to any one of claims 1 to 6, characterized in that, In step (4), the activated precursor mixture is heated to 680~760°C and held for 75~86 minutes, and then the temperature is increased to 1100~1230°C and held for 30~40 minutes.

10. Tungsten carbide nanowires obtained by the method according to any one of claims 1 to 9, characterized in that, The tungsten carbide nanowires have a diameter of 50–110 nm, a radial dimension difference of 3–8 nm, a length of 20–100 μm, an aspect ratio of 200–1200, and a tungsten carbide phase purity of ≥98%.

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