A nano-tungsten carbide and its preparation method

Abstract

This invention provides nano-tungsten carbide and its preparation method, belonging to the field of nanopowders. The method for preparing nano-tungsten carbide includes the following steps: gaseous tungsten oxide (after vaporization) is passed into an organic solvent to obtain a dispersion of nano-tungsten oxide; the dispersion is mixed with a building agent and dried, allowing the nano-tungsten oxide to enter the interior of carbon nanotubes, resulting in a building material; the building agent includes carbon nanotubes; the building material is then subjected to reduction carbonization to obtain the nano-tungsten carbide. This invention utilizes the high activity of nano-tungsten oxide prepared by sublimation, enabling rapid adsorption into the interior of carbon nanotubes, thereby achieving the preparation of the building material; furthermore, after the nano-tungsten oxide is introduced into the carbon nanotubes, the carbon nanotubes restrict the growth of powder particles during the reduction carbonization process, achieving controllable powder size.

Description

Technical Field

[0001] This invention relates to the field of nanopowders, specifically to a nano-tungsten carbide and its preparation method. Background Technology

[0002] Nano-tungsten carbide (WC) is a novel functional material with high hardness, high thermal stability, and high wear resistance. It breaks the traditional constraint that high hardness and high toughness cannot be achieved simultaneously in cemented carbide, making nano-tungsten carbide powder a promising material for applications in tools, precision molds, drill bits, and other fields.

[0003] Solid-state processing, as the primary method for preparing nano-tungsten carbide (WC), has been widely applied. However, the quality of nano-tungsten carbide prepared using the pushboat process in the solid-state method is not high, mainly due to uneven particle size distribution, poor dispersibility, and small specific surface area. Nano-tungsten carbide powder prepared by the rotary reduction method in the solid-state method has better quality and can increase the specific surface area, but the problem of uneven particle size distribution remains largely unresolved. Summary of the Invention

[0004] This invention provides a nano-tungsten carbide and its preparation method, wherein the nano-tungsten carbide prepared by this invention has a uniform particle size distribution.

[0005] This invention provides a method for preparing nano-tungsten carbide, comprising the following steps:

[0006] The gaseous tungsten oxide obtained by vaporizing tungsten oxide is passed into an organic solvent to obtain a dispersion of nano-tungsten oxide.

[0007] The dispersion of nano-tungsten oxide is mixed with a building agent and then dried. The nano-tungsten oxide enters the interior of the carbon nanotubes to obtain a building material. The building agent includes carbon nanotubes.

[0008] The building material is reduced and carbonized to obtain the nano-tungsten carbide.

[0009] Preferably, the mass ratio of the nano-tungsten oxide to the carbon nanotubes is 5~15:1.

[0010] Preferably, the building agent is a slurry;

[0011] The slurry includes carbon black, phenolic resin, carbon nanotubes, and ethanol;

[0012] The mass ratio of carbon nanotubes to carbon black is 3~9:1;

[0013] The mass ratio of carbon nanotubes to phenolic resin is 2~10:1.

[0014] Preferably, the building agent is a solid with a porous structure;

[0015] The preparation method of the building agent includes the following steps:

[0016] The building agent is obtained by mixing carbon black, phenolic resin and carbon nanotubes, pressing and sintering them.

[0017] Preferably, the reduction carbonization is carried out in a rotary reduction furnace;

[0018] The reduction carbonization temperature is 800~1000℃, and the holding time is 30~60min.

[0019] Preferably, the reduction carbonization is carried out in a tube furnace;

[0020] The reduction carbonization temperature is 800~1000℃, and the holding time is 60~90min.

[0021] Preferably, after the reduction carbonization, it further includes:

[0022] The product obtained by reduction and carbonization is quenched, separated and dried to obtain tungsten carbide preform;

[0023] The tungsten carbide preform is passivated and pulverized to obtain the nano-tungsten carbide.

[0024] Preferably, the quenching agent used for quenching includes ethanol, water, or liquid nitrogen;

[0025] The quenching is carried out under stirring conditions, and the quenching time is 60~120 minutes.

[0026] Preferably, the passivation is carried out in a hydrogen atmosphere; the passivation temperature is 1100~1200℃ and the time is 20~90min.

[0027] The present invention also provides nano-tungsten carbide prepared by the preparation method described in the above technical solution.

[0028] This invention utilizes the high activity of nano-tungsten oxide prepared by sublimation of tungsten oxide, which can be quickly adsorbed into the interior of carbon nanotubes, thereby realizing the preparation of building materials; and after the nano-tungsten oxide is introduced into the interior of carbon nanotubes, the carbon nanotubes restrict the growth of powder particles during the reduction carbonization process, achieving the effect of controllable powder size, thus making the prepared tungsten carbide particle size distribution more uniform.

[0029] In addition, the nano-tungsten oxide prepared by sublimation in this invention has high activity, which is conducive to its rapid entry into the interior of carbon nanotubes. Therefore, no additional treatment is required to improve the activity of carbon nanotubes to achieve the adsorption of nano-tungsten oxide by carbon nanotubes, thereby improving the efficiency of subsequent processes and facilitating large-scale industrialization.

[0030] Furthermore, the separation of tungsten oxide and carbon black often occurs during the reduction carbonization process for preparing nano-tungsten carbide, leading to carbon-deficient phases and excessive free carbon in the prepared nano-tungsten carbide, resulting in low-quality nano-tungsten carbide. In this invention, a slurry of carbon black and phenolic resin is prepared first, or carbon black, phenolic resin, and carbon nanotubes are prepared into a porous block. This allows the slurry to fully adhere to the surface of the nano-tungsten oxide or allows the nano-tungsten oxide to penetrate into the pores. This avoids abnormal growth caused by contact between nano-tungsten oxide particles during subsequent reduction and oxidation processes, and also prevents the formation of nano-tungsten carbide lines, which would prevent the preparation of powder particles. Therefore, the presence of carbon black and phenolic resin serves two purposes: firstly, it provides a reducing agent and carbon source; secondly, it isolates the carbon nanotube adsorbent and the nano-tungsten oxide particles within it, greatly reducing particle growth during gas-phase migration.

[0031] Furthermore, due to the high-temperature resistance of carbon nanotubes, they adhere to the surface of tungsten carbide particles, so they need to be removed; otherwise, composite particles will form, reducing the quality of the nano-tungsten carbide. In this invention, the mixture after reduction and carbonization is quenched, separated, and passivated to fully remove residual carbon nanotubes, ensuring the quality of the prepared nano-tungsten carbide.

[0032] In summary, the present invention employs a method for preparing nano-tungsten carbide, which can effectively solve the problems of uneven particle size distribution and small specific surface area of ​​tungsten carbide powder prepared by traditional processes. Ultimately, it achieves the technical effect of controllable particle size of nano-tungsten carbide powder, and the prepared nano-tungsten carbide has complete crystal structure, complete carbonization, and low free carbon content. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation of nano-tungsten carbide in an embodiment of the present invention;

[0034] Figure 2 SEM image of the nano-tungsten carbide prepared in Example 1;

[0035] Figure 3 The image shows a comparison of the particle size distribution of the nano-tungsten carbide prepared in Example 2 and Comparative Example 1. Detailed Implementation

[0036] This invention provides a method for preparing nano-tungsten carbide, comprising the following steps:

[0037] The gaseous tungsten oxide obtained by vaporizing tungsten oxide is passed into an organic solvent to obtain a dispersion of nano-tungsten oxide.

[0038] The dispersion of nano-tungsten oxide is mixed with a building agent and then dried. The nano-tungsten oxide enters the interior of the carbon nanotubes to obtain a building material. The building agent includes carbon nanotubes.

[0039] The building material is reduced and carbonized to obtain the nano-tungsten carbide.

[0040] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.

[0041] In this invention, gaseous tungsten oxide, after being vaporized, is passed into an organic solvent to obtain a dispersion of nano-tungsten oxide.

[0042] In this invention, the vaporization temperature is preferably 850°C.

[0043] In this invention, the gaseous tungsten oxide is preferably introduced into an organic solvent under the influence of argon gas; the organic solvent preferably includes ethanol.

[0044] In this invention, the introduction is preferably carried out under stirring conditions, and the stirring time is preferably 30 to 90 minutes. In specific embodiments of this invention, the stirring time can be 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, or 90 minutes.

[0045] The nano-tungsten oxide obtained by sublimation has high activity.

[0046] After obtaining a dispersion of nano-tungsten oxide, the present invention mixes the dispersion of nano-tungsten oxide with a building agent and then dries it, so that the nano-tungsten oxide enters the interior of the carbon nanotubes to obtain a building material.

[0047] In this invention, the mass ratio of nano-tungsten oxide to carbon nanotubes is preferably 5 to 15:1. In specific embodiments of this invention, the mass ratio of nano-tungsten oxide to carbon nanotubes can be 5:1, 8:1, 10:1, 12:1 or 15:1.

[0048] In this invention, the building agent is preferably a slurry or a solid with a porous structure.

[0049] When the building agent is a slurry, the slurry preferably includes carbon black, phenolic resin, carbon nanotubes, and ethanol; the mass ratio of carbon nanotubes to carbon black is preferably 3 to 9:1. In specific embodiments of the present invention, the mass ratio of carbon nanotubes to carbon black can be 3:1, 4:1, 5:1, 5:1, 7:1, 8:1, or 9:1; the mass ratio of carbon nanotubes to phenolic resin is preferably 2 to 10:1. In specific embodiments of the present invention, the mass ratio of carbon nanotubes to phenolic resin can be 2:1, 3:1, 4:1, 5:1, 5:1, 7:1, 8:1, 9:1, or 10:1; the mass ratio of carbon nanotubes to ethanol is preferably 1:2 to 5. In specific embodiments of the present invention, the mass ratio of carbon nanotubes to ethanol can be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, or 5:1.

[0050] When the building agent is preferably a solid with a porous structure, the preparation method of the building agent preferably includes the following steps:

[0051] The building agent is obtained by mixing carbon black, phenolic resin and carbon nanotubes, pressing and sintering them.

[0052] In this invention, the molding pressure is preferably 180~200MPa. In specific embodiments of this invention, the molding pressure can be 180MPa, 190MPa, or 200MPa. The sintering temperature is preferably 800~900℃, and the sintering time is preferably 25~45min. In specific embodiments of this invention, the sintering temperature can be 800℃, 820℃, 850℃, 880℃, or 900℃, and the sintering time can be 25min, 30min, 35min, 40min, or 45min.

[0053] After sintering, a porous structure is formed.

[0054] In this invention, when the building agent is a slurry, the mixing is preferably carried out under stirring conditions, and the mixing time is preferably 60-120 min. In specific embodiments of this invention, the mixing time can be 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min.

[0055] In this invention, when the building agent is a solid with a porous structure, the mixing is preferably carried out under ultrasonic conditions, and the mixing time is preferably 30 to 120 minutes. In specific embodiments of this invention, the mixing time can be 30 minutes, 50 minutes, 80 minutes, 100 minutes, or 120 minutes.

[0056] After obtaining the building material, the present invention performs reduction carbonization on the building material to obtain the nano-tungsten carbide.

[0057] In this invention, the reductive carbonization is preferably carried out in a mixture of carbon monoxide and hydrogen or in the presence of carbon monoxide.

[0058] In this invention, when the building agent is a slurry, the reduction carbonization is preferably carried out in a rotary reduction furnace;

[0059] In this invention, the rotary reduction furnace preferably includes, from the furnace head to the furnace tail, a first temperature zone, a second temperature zone, a third temperature zone, a fourth temperature zone, a fifth temperature zone, and a sixth temperature zone; the temperature of the first temperature zone is preferably 850~880℃; the temperature of the second temperature zone is preferably 880~910℃; the temperature of the third temperature zone is preferably 910~930℃; the temperature of the fourth temperature zone is preferably 930~950℃; the temperature of the fifth temperature zone is preferably 980~1000℃; and the temperature of the sixth temperature zone is preferably 980~1080℃; the rotation speed of the material in the rotary reduction furnace is preferably 3~6 r / min; in the specific implementation of this invention... In the embodiment, the temperature of the first temperature zone can be 850℃, 860℃, 870℃ or 880℃; the temperature of the second temperature zone can be 880℃, 890℃, 900℃ or 910℃; the temperature of the third temperature zone can be 910℃, 920℃ or 930℃; the temperature of the fourth temperature zone can be 930℃, 940℃ or 950℃; the temperature of the fifth temperature zone can be 980℃, 990℃ or 1000℃; the temperature of the sixth temperature zone can be 980℃, 1000℃ or 1080℃; and the rotation speed of the material in the rotary reduction furnace can be 3r / min, 4r / min, 5r / min or 6r / min.

[0060] In this invention, the holding time for reduction carbonization is preferably 30 to 60 minutes. In specific embodiments of this invention, the holding time for reduction carbonization can be 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

[0061] In this invention, when the building agent is a solid with a porous structure, the reduction carbonization is preferably carried out in a tube furnace;

[0062] The preferred temperature for reduction carbonization is 800~1000℃, and the preferred holding time is 60~90min. In specific embodiments of the present invention, the temperature for reduction carbonization can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 950℃ or 1000℃, and the holding time can be 60min, 70min, 80min or 90min.

[0063] In this invention, after the reduction carbonization, it preferably further includes:

[0064] The product obtained by reduction and carbonization is quenched, separated and dried to obtain tungsten carbide preform;

[0065] The tungsten carbide preform is passivated and pulverized to obtain the nano-tungsten carbide.

[0066] In this invention, the quenching agent used for quenching preferably includes ethanol, water or liquid nitrogen, the quenching is preferably carried out under stirring conditions, and the quenching time is preferably 60~120 min. In specific embodiments of this invention, the quenching time can be 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min.

[0067] In this invention, the passivation is preferably carried out in a hydrogen atmosphere; the passivation temperature is preferably 1100~1200℃, and the passivation time is preferably 20~90min. In specific embodiments of this invention, the passivation temperature can be 1100℃, 1120℃, 1140℃, 1160℃, 1180℃ or 1200℃, and the time can be 20min, 30min, 40min, 50min, 60min, 70min, 80min or 90min.

[0068] The present invention also provides nano-tungsten carbide prepared by the preparation method described in the above technical solution.

[0069] Figure 1 The flowchart for preparing nano-tungsten carbide in an embodiment of the present invention is as follows:

[0070] Tungsten oxide is vaporized and sublimated to obtain nano-tungsten oxide; the nano-tungsten oxide is batched and assembled to obtain a building material; the building material is reduced and carbonized to obtain a mixture; the mixture is quenched and passivated to obtain nano-tungsten carbide.

[0071] The following detailed description of the nano-tungsten carbide and its preparation method provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0072] The preparation method of building agent A in the embodiment is as follows:

[0073] Mix 100g carbon nanotubes, 20g carbon black, 20g phenolic resin (BR2123F from Henan Borun New Materials Co., Ltd.) and 500mL ethanol to obtain building agent A.

[0074] The preparation method of the building agent B in the embodiment is as follows:

[0075] 100g of carbon nanotubes, 20g of carbon black and 20g of phenolic resin (BR2123F from Henan Borun New Materials Co., Ltd.) were mixed and molded under a pressure of 200MPa to obtain the precursor.

[0076] The precursor was sintered at 900°C for 30 minutes to obtain building agent B.

[0077] Preparation Method 1

[0078] 1. 1000g of tungsten oxide was vaporized and sublimated at 850℃. The sublimated tungsten oxide was then passed into 2000mL of ethanol and stirred for 30~90min to obtain a nano tungsten oxide dispersion.

[0079] 2. Add building agent A to the dispersion in step 1 and stir to mix for 60-120 minutes. After stirring, dry to obtain the building material.

[0080] 3. The material described in step 2 is fed into a rotary kiln for reduction and carbonization. The temperatures of the six temperature zones from the furnace head to the furnace tail are 880℃, 910℃, 930℃, 930℃, 990℃ and 990℃, respectively. The rotation speed of the material is 5r / min and the time is 30~60min. After the heat preservation is completed, the mixture is obtained.

[0081] 4. Quench the mixture from step 3 in liquid nitrogen, stir, and then centrifuge for 60-120 minutes. After filtration and drying, obtain the tungsten carbide preform.

[0082] 5. Using a molybdenum wire furnace, the tungsten carbide preform from step 4 is passivated under a hydrogen atmosphere. After crushing, nano-tungsten carbide is obtained. The passivation temperature is 1100~1200℃, and the passivation time is 20min~90min. The BET of the nano-tungsten carbide is 4.0~4.5 μm. 2 / g.

[0083] Preparation Method 2

[0084] 1. 1000g of tungsten oxide was vaporized and sublimated at 850℃. The sublimated tungsten oxide was then passed into 2000mL of ethanol and stirred for 30~90min to obtain a nano tungsten oxide dispersion.

[0085] 2. Add building agent B to the dispersion in step 1 and sonicate for 30-120 minutes. After sonication, dry to obtain the building material.

[0086] 3. The coating material described in step 2 is fed into a tube furnace for reduction and carbonization at a temperature of 800~1000℃ for 90 minutes. After the heat treatment is completed, a mixture is obtained.

[0087] 4. Quench the mixture from step 3 in liquid nitrogen, stir, and then centrifuge for 60-120 minutes. After filtration and drying, obtain the tungsten carbide preform.

[0088] 5. Using a molybdenum wire furnace, the tungsten carbide preform from step 4 is passivated under a hydrogen atmosphere. After crushing, nano-tungsten carbide is obtained. The passivation temperature is 1100~1200℃, and the passivation time is 20~90 min. The BET of the nano-tungsten carbide is 4.0~4.5 μm. 2 / g.

[0089] Preparation parameters of Examples 1-5 and BET of nano-tungsten carbide

[0090]

[0091] Comparative Example 1

[0092] 1. Ammonium metatungstate was placed in an alumina crucible and calcined in a muffle furnace at a temperature of 750℃ for 6 hours to obtain WO3 agglomerates.

[0093] 2. The WO3 agglomerates obtained in step 1 were crushed using an air jet mill for 45 minutes at a flow rate of 180 m³ / min. 3 At a gas pressure of 0.05 MPa, crushed WO3 (particle size <0.5μm) and high-purity carbon black (purity 99.95%, carbon black mass is 6.2% of WO3 mass) are mixed by a vertical plow to obtain a mixture of WO3 and carbon black.

[0094] 3. After mixing WO3 and carbon black with solvent, spray granulation and room temperature drying are performed. The WO3 and carbon black slurry in step 2 is spray granulated to obtain spherical mixture.

[0095] 4. The spherical mixture from step 3 is reduced and carbonized in a rotary reduction furnace with six temperature zones under inert gas protection. The temperatures of the six temperature zones from the furnace head to the furnace tail are 880℃, 910℃, 930℃, 930℃, 990℃ and 990℃ respectively. The rotation speed of the material is 5 r / min and the time from feeding to discharging is 40 min, resulting in a pre-carbonized material with a chemical composition of W+WC+W2C.

[0096] 5. The pre-carburized material from step 4 was passivated in a hydrogen gas environment using a molybdenum wire furnace. Passivation yielded nano-tungsten carbide with complete and uniformly distributed grains. The passivation temperature was 1450℃, and the passivation time was 20 minutes. The final nano-tungsten carbide powder had a specific surface area of ​​3.98 m². 2 / g.

[0097] Comparative Example 2

[0098] 1. WO3 is loaded into a cylindrical mold with dimensions of φ20*100 mm and pressed into shape using an isostatic press at a pressure of 200MPa and a holding time of 5min to obtain tungsten oxide blank;

[0099] 2. The tungsten oxide preform is fed into an oxyacetylene flame at 2500℃ (where the volume ratio of acetylene to oxygen is 2:5, and the acetylene flow rate is 3 L / min), causing the tungsten oxide to vaporize instantaneously, yielding tungsten oxide vapor. Nitrogen gas (flow rate 9 L / min) is used to introduce the obtained tungsten oxide vapor into a condensation and collection device, where the temperature of the condensation and collection device is 5℃, and the collection time is 1 hour. After homogeneous nucleation and growth of tungsten oxide, the tungsten oxide vapor is condensed to obtain nano-tungsten oxide particles, resulting in nano-tungsten oxide particles with a specific surface area of ​​16.76 m². 2 / g;

[0100] 3. The obtained nano-tungsten oxide particles were reduced in a carbon monoxide reduction furnace at a temperature of 650℃ for 45 minutes to obtain nano-tungsten powder with complete and uniform grain distribution.

[0101] 4. The obtained nano-tungsten powder and carbon black were placed in a mixer and stirred for 6 hours to obtain a mixed powder, in which the mass percentage of carbon black was 6.115%. The mixed powder was then carbonized in a carbonization furnace at a temperature of 900℃ for 90 minutes to obtain nano-tungsten carbide with complete and uniform grain distribution and a specific surface area of ​​4.14 m². 2 / g.

[0102] Comparative Example 3

[0103] 1. Modification of carbon nanotubes: 10g of carbon nanotubes were placed in 100mL of concentrated nitric acid with a mass concentration of 68% and ultrasonically dispersed at 80℃ for 30min. Then, the mixture was refluxed at 90℃ for 1~5h. After cooling to room temperature, the mixture was diluted with deionized water and filtered until neutral. The powder was then placed in a vacuum drying oven and dried at 90℃ for 5h to obtain modified carbon nanotubes.

[0104] 2. Weigh out 3% of the modified carbon nanotubes (ammonium paratungstate solution by mass) and mix with the ammonium paratungstate solution. Add citric acid monohydrate and polyethylene glycol reagent (both dissolved in 1% of the mixed solution volume). Stir thoroughly, then add formic acid dropwise until the pH of the solution reaches 3. Place the solution in a constant temperature stirrer and stir for 40 hours at 70℃ and 30 r / min to form a sol. Place the sol in a vacuum drying oven at 200℃ for 10 hours to prepare a gel. Grind the gel into powder and pass it through a 300-mesh sieve.

[0105] 3. The ground and sieved gel was placed in a reduction furnace. Flowing hydrogen with a purity of 99.99% was used as the reducing carrier gas. The hydrogen flow rate was 280 mL / min. After reduction at 700℃ for 5 h, the furnace was cooled to prepare a carbon nanotube / tungsten nanopowder composite powder material with a carbon nanotube volume content of 12%.

[0106] 4. The carbon nanotube / tungsten nanopowder composite powder material was ground and crushed. After crushing, it was centrifuged, dried, and then passivated using a molybdenum wire furnace at 1000℃ for 50 minutes to obtain tungsten nanopowder with a BET of 4.0 g / cm³. 3 .

[0107] Comparative Example 4

[0108] 1. Using tungsten powder with an average particle size of 100 nm as raw material, alcohol-soluble phenolic resin is dissolved in anhydrous ethanol to prepare an ethanol solution of phenolic resin with a concentration of 0.5 g / mL. 300 mL of the above phenolic resin ethanol solution is added to each kg of nano-W powder, and the mixture is treated in an ultrasonic dispersion device for 3 h with stirring. Then, the slurry is heated to 100 °C to evaporate the anhydrous ethanol, resulting in a mixture of phenolic resin-coated nano-W particles.

[0109] 2. Carbonizing the mixture in a vacuum furnace at 950℃ for 60 minutes with a vacuum degree of 200Pa yields nano-WC powder with an average particle size of 118nm and a carbon content of 8.72%.

[0110] 3. The high-carbon-content nano-WC powder obtained by vacuum carbonization was heat-treated in a tube furnace under H2 atmosphere at a temperature of 950℃ for 60 min at an H2 flow rate of 2.0 L / min. The resulting nano-WC powder had a BET of 3.5 m. 2 / g, with a carbon content of 6.15%.

[0111] Figure 2 The image shows a SEM image of the nano-tungsten carbide prepared in Example 1.

[0112] Depend on Figure 2 It can be seen that the nano-tungsten carbide prepared by the present invention has high quality: the nano-tungsten carbide powder has complete crystal form, sufficient carbonization, low free carbon, and concentrated particle size distribution.

[0113] Figure 3 The image shows a comparison of the particle size distribution of the nano-tungsten carbide prepared in Example 2 and Comparative Example 1.

[0114] Depend on Figure 3It is evident that the nano-tungsten carbide particles prepared by the construction method of this invention have a more concentrated particle size distribution, while existing methods produce nano-tungsten carbide powders with a wider particle size distribution. In industrial-scale mass production, this method can effectively improve the quality of the prepared nano-tungsten carbide powder, exhibiting controllable particle size and eliminating the need for batch processing to meet usage requirements, thus shortening the process flow and generating greater economic benefits. Furthermore, the final nano-tungsten carbide powder product exhibits complete crystal structure, full carbonization, and low free carbon content.

[0115] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing nano-tungsten carbide, characterized in that, Includes the following steps: The gaseous tungsten oxide obtained by vaporizing tungsten oxide is passed into an organic solvent to obtain a dispersion of nano-tungsten oxide. The dispersion of nano-tungsten oxide is mixed with a building agent and then dried. The nano-tungsten oxide enters the interior of the carbon nanotubes to obtain the building material. The building agent is a slurry or a solid with a porous structure; The slurry includes carbon black, phenolic resin, carbon nanotubes, and ethanol; The mass ratio of carbon nanotubes to carbon black is 3~9:1; The mass ratio of carbon nanotubes to phenolic resin is 2~10:1; The preparation method of the building agent when it is a solid with a porous structure includes the following steps: The building agent is obtained by mixing carbon black, phenolic resin and carbon nanotubes, pressing and sintering them together. The mass ratio of the nano-tungsten oxide to the carbon nanotubes in the building agent is 5~15:1; The building material is reduced and carbonized to obtain the nano-tungsten carbide.

2. The preparation method according to claim 1, characterized in that, The reduction carbonization is carried out in a rotary reduction furnace; The reduction carbonization temperature is 800~1000℃, and the holding time is 30~60min.

3. The preparation method according to claim 1, characterized in that, The reduction carbonization is carried out in a tube furnace; The reduction carbonization temperature is 800~1000℃, and the holding time is 60~90min.

4. The preparation method according to claim 1, characterized in that, After reduction and carbonization, it also includes: The product obtained by reduction and carbonization is quenched, separated and dried to obtain tungsten carbide preform; The tungsten carbide preform is passivated and pulverized to obtain the nano-tungsten carbide.

5. The preparation method according to claim 4, characterized in that, The quenching agent used for quenching includes ethanol, water, or liquid nitrogen; The quenching is carried out under stirring conditions, and the quenching time is 60~120 minutes.

6. The preparation method according to claim 4, characterized in that, The passivation is carried out in a hydrogen atmosphere; the passivation temperature is 1100~1200℃ and the time is 20~90min.

7. The nano-tungsten carbide prepared by the preparation method according to any one of claims 1 to 6.

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