Nanometer tungsten carbide and its preparation method

Abstract

This application belongs to the field of powder metallurgy technology, specifically a nano-tungsten carbide and its preparation method. The preparation method includes: mixing tungsten oxide and a carbon source, sieving, then sequentially adding a structural agent and performing pressing and centrifugal granulation to obtain spherical material; holding the spherical material at 400~600℃ for 20~40min in a nitrogen atmosphere, then sequentially performing reduction carburization and batch carbon addition to obtain carbide material; finally, passivating the carbide material and crushing it to obtain nano-tungsten carbide. This application uses a simple centrifugal granulation technique, which solves the problem of hollow material, strengthens the structural strength of the spherical material, and avoids the problem of poor consistency of tungsten carbide powder caused by the crushing of spherical material in subsequent processes; by introducing a structural agent to construct the internal macroscopic structure of the spherical material to form gas channels, the problem of gas generated during the reaction process being destroyed by the material structure is avoided, resulting in a significant improvement in the quality and production efficiency of nano-tungsten carbide powder.

Description

Technical Field

[0001] This application belongs to the field of powder metallurgy technology, specifically a nano-tungsten carbide and its preparation method. Background Technology

[0002] Nano-tungsten carbide powder is a novel functional material with high hardness, high thermal stability, and high wear resistance. It breaks the traditional limitation of cemented carbide where high hardness and high toughness cannot be simultaneously achieved, making nano-tungsten carbide powder a promising candidate for applications in tools, precision molds, drill bits, and other fields. Currently, the demand for nano-tungsten carbide powder in high-end cemented carbide products is increasing, making the development of technologies for the mass production of high-quality tungsten carbide powder a current research focus.

[0003] Traditional static push-boat and dynamic rotary preparation are the mainstream technologies for preparing nano-tungsten carbide powder, and both are widely used in actual production activities. To improve production efficiency, dynamic rotary preparation of nano-tungsten carbide powder is receiving increasing attention, with its main advantages lying in the process stages. Dynamic rotary technology can produce finer-grained tungsten powder and can continuously produce large quantities of powder. However, like traditional static push-boat, dynamic rotary technology still requires the tungsten powder to be mixed with carbon black before the preparation of tungsten carbide powder.

[0004] To address this, patent CN117963924B discloses an optimized method for preparing nano-tungsten carbide powder using dynamic rotation technology. This method offers certain advantages over traditional dynamic rotation technology. However, it requires mixing the materials before spray granulation to form spherical mixtures. This granulation process necessitates continuous stirring, which can cause stratification of various substances within the material. Carbon black tends to accumulate on the surface of the slurry, resulting in a higher carbon content in the subsequently prepared spherical particles, a significant factor limiting the quality of the tungsten carbide powder. Furthermore, the spherical particles prepared by spray granulation are, to some extent, hollow. During subsequent material transfer and dynamic reduction processes, these particles may break, leading to decreased powder flowability and poor consistency in the tungsten carbide powder. Additionally, the wide particle size distribution of the sprayed material during rotational reduction carbonization results in inconsistent time spent in the high-temperature zone, further affecting the overall powder consistency. To address these issues, the patent with publication number CN120024897B optimized the process and adopted a novel construction approach to control the particle size of the powder. However, this method is relatively complicated and faces challenges in large-scale application due to its difficult operation and narrow process adjustment window. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a nano-tungsten carbide and its preparation method. By constructing the macroscopic distribution structure of the material through a novel mixing process, the problem of poor particle size uniformity, long process flow, and high cost of tungsten carbide powder prepared by existing processes can be effectively solved, resulting in a significant improvement in both the quality and production efficiency of nano-tungsten carbide powder.

[0006] According to the first aspect of this application, a method for preparing nano-tungsten carbide powder is proposed, comprising the following steps: S1. Mix tungsten oxide and carbon source, and sieve to obtain a mixture; S2. Add a structural agent to the mixture and press it into strips, then centrifuge and granulate it to obtain spherical material; S3. In a nitrogen atmosphere, the spherical material is pretreated by holding it at 400~600℃ for 20~40 minutes to obtain the structural material; S4. The structural material is reduced and carbonized, and then carbonized in batches to obtain carbonized material; S5. Passivate the carbide material and crush it to obtain the nano-tungsten carbide.

[0007] In the above technical solution, in step S2, a structural agent is added during the granulation process, and the traditional spray granulation is replaced with a simpler centrifugal granulation to prepare solid spherical materials, thereby strengthening the structural strength of the spherical materials. At the same time, the introduced structural agent can construct the macroscopic structure inside the spherical materials. In step S3, during low-temperature pretreatment, the structural agent will gradually undergo decomposition and gasification reactions at 400°C, thereby forming vacancies in the original positions. When there are enough vacancies, they can form gas channels. When the temperature is further increased to about 600°C, the structural agent will coke, which can further strengthen the internal structure of the spherical materials. Afterwards, the obtained structural materials are reduced and carbonized, then passivated after batch carbonization, and crushed to obtain high-quality nano-tungsten carbide powder.

[0008] Furthermore, in step S1, the tungsten oxide includes at least one of yellow tungsten, blue tungsten, purple tungsten, or brown tungsten; the carbon source includes carbon black or an organic carbon source; and the molar ratio of the tungsten oxide (calculated as WO3) to the carbon source (calculated as C) is 1:(2.7~3.2).

[0009] Furthermore, in step S1, the specific surface area of ​​the tungsten oxide is 4.0~8.0 m². 2 / g.

[0010] Furthermore, in step S2, the structural agent includes glucose and maltose, and the mass of the structural agent is 1% to 3% of the total mass of the tungsten oxide and the carbon source; the particle size of the spherical material is 2 to 5 mm, and the loose packing density is 2 to 4 g / cm³. 3 .

[0011] Furthermore, in step S2, the rotation speed of the centrifugal granulation is 20~60 rpm.

[0012] Furthermore, in step S4, the temperature of the reduction carbonization is 900~1100℃, and the time is 20~60min.

[0013] Furthermore, in step S4, the carbonized material contains WC and W2C.

[0014] Furthermore, in step S5, the passivation temperature is 1200~1500℃ and the time is 20~90min.

[0015] Furthermore, in step S5, the nano-tungsten carbide has a combined carbon content ≥6.01%, a free carbon content ≤0.15%, and a specific surface area of ​​3.5~5.0 m². 2 / g.

[0016] Furthermore, the particle size of the nano-tungsten carbide is 10~150nm.

[0017] Furthermore, in step S1, the mixing includes ball milling or plow milling.

[0018] Furthermore, step S1 also includes mixing tungsten oxide, a carbon source, and a binder, wherein the binder includes PEG (polyethylene glycol) or PVA (polyvinyl alcohol), and the mass of the binder is 1% to 3% of the total mass of the tungsten oxide and the carbon source; Introducing a binder makes the spherical material structure more compact, ensuring that the spherical material does not break during subsequent processes. Tungsten trioxide and carbon black are tightly bonded together, preventing the separation of tungsten oxide and carbon black, which is conducive to the chemical reaction and ensures the consistency of product quality.

[0019] Furthermore, step S4 also includes: reducing and carbonizing the structural material, then ball milling it for 30-60 minutes, and then adding carbon in batches to obtain carbonized material.

[0020] According to a second aspect of this application, this application proposes a nano-tungsten carbide, which is prepared by the above-described method for preparing nano-tungsten carbide.

[0021] This application proposes a nano-tungsten carbide and its preparation method, which produces the following beneficial effects: The simple centrifugal granulation technique solves the problem of hollow materials, strengthens the structural strength of spherical materials, and avoids the problem of poor consistency of tungsten carbide powder caused by the breakage of spherical materials in subsequent processes; by introducing a structural agent to construct the macroscopic structure inside the spherical material, gas channels are formed inside, avoiding the problem of gas generated during the reaction destroying the material structure, thus significantly improving the quality and production efficiency of nano-tungsten carbide powder. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a microstructure diagram of the surface of the spherical material prepared by centrifugal granulation in Example 1; Figure 2 This is a structural diagram of the spherical material prepared by spray granulation in Comparative Example 1; Figure 3 Microstructure diagram of the structural material prepared in Example 1; Figure 4 The image shows the microstructure of the nano-tungsten carbide prepared in Example 1 and Comparative Example 1.

[0024] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] According to the first aspect of this application, a method for preparing nano-tungsten carbide powder is proposed, comprising the following steps: S1. Mix tungsten oxide, carbon source and binder, and sieve to obtain a mixture; Preferably, the tungsten oxide includes at least one of yellow tungsten, blue tungsten, purple tungsten, or brown tungsten; the carbon source includes carbon black or an organic carbon source; the molar ratio of tungsten oxide (WO3) to the carbon source (C) is 1:(2.7~3.2); and the specific surface area of ​​the tungsten oxide is 6~7 m². 2 / g. In some preferred embodiments of this application, tungsten oxide and carbon source are mixed by ball milling or plowing, and PEG or PVA can be introduced as a binder during mixing. The mass of the binder is 1.5% to 2% of the total mass of tungsten oxide and carbon source.

[0027] S2. Add a structural agent to the mixture and press it into strips, then centrifuge and granulate it to obtain spherical material; Preferably, the structural agent includes glucose and maltose, and the mass of the structural agent is 1% to 3% of the total mass of tungsten oxide and carbon source; the particle size of the spherical material is 2 to 5 mm, and the loose packing density is 2 to 3 g / cm³. 3 The rotation speed used during centrifugal granulation is 30~40 rpm.

[0028] S3. Pre-treat the spherical material in a nitrogen atmosphere by holding it at 400~600℃ for 20~40min to obtain the structural material; In some preferred embodiments of this application, spherical materials can be pre-treated in a tube furnace or a rotary kiln. Since the material can be dynamically tumbled in a rotary kiln and heated more evenly, a rotary kiln is preferred.

[0029] S4. Reduce and carbonize the structural material, then add carbon in batches to obtain carbonized material; In some preferred embodiments of this application, the structural material can be reduced and carbonized at 900-1100°C for 20-60 minutes, then ball-milled for 30-60 minutes, and finally batch carbonized to obtain carbonized material, the main components of which are WC and W2C. Specifically, batch carbonization involves first crushing the reduced and carbonized structural material and testing its carbon content, then adding a carbon source to a preset carbon content of 6.15%-6.20%.

[0030] S5. Passivate the carbide material and crush it to obtain nano-tungsten carbide; Preferably, in some preferred embodiments of this application, the carbide material can be passivated in a molybdenum wire furnace under a hydrogen atmosphere at a temperature of 1200~1500℃ for 20~90 minutes.

[0031] According to a second aspect of this application, a nano-tungsten carbide is provided, which is prepared by the above-described method for preparing nano-tungsten carbide; its combined carbon content is ≥6.01%, free carbon content is ≤0.15%, and specific surface area (BET) is 3.5~5.0 m². 2 / g, with a particle size in the range of 50~150nm.

[0032] The technical solution of this application will be further described below with reference to specific embodiments. In the following embodiments and comparative examples, the preset carbon content for batch carbon replenishment is 6.20%.

[0033] Example 1

[0034] A method for preparing nano-tungsten carbide powder includes the following steps: S1. Tungsten oxide and carbon black are ball-milled and mixed for 240 minutes. After mixing, the mixture is sieved and dried to obtain a mixture. The molar ratio of tungsten oxide (WO3) to carbon black (C) is 1:2.7. S2. Place the mixture in an extruder and press it into strips. During the pressing process, add glucose as a structural agent. The mass of glucose is 1.5% of the total mass of tungsten oxide and carbon black. After pressing, centrifuge and granulate to obtain spherical material. S3. In a nitrogen atmosphere, the spherical material is placed in a tube furnace and held at 600℃ for 20 minutes for pretreatment to obtain the structural material. S4. Place the structural material in a tube furnace and hold it at 950℃ for 40 minutes for reduction carbonization, then ball mill it for 30 minutes, and then add carbon in batches to obtain carbonized material. S5. Under a hydrogen atmosphere, the carbide material was placed in a molybdenum wire furnace and passivated at 1200℃ for 90 minutes. After crushing, nano-tungsten carbide was obtained, with a combined carbon content of 6.05%, a free carbon content of 0.12%, and a BET of 4.07 g / cm³. 3 .

[0035] Example 2

[0036] A method for preparing nano-tungsten carbide powder includes the following steps: S1. Tungsten oxide and carbon black are ball-milled and mixed for 240 minutes. After mixing, the mixture is sieved and dried to obtain a mixture. The molar ratio of tungsten oxide (WO3) to carbon black (C) is 1:3.2. S2. Place the mixture in an extruder and press it into strips. During the pressing process, add maltose as a structural agent. The mass of maltose is 1.5% of the total mass of tungsten oxide and carbon black. After pressing, centrifuge and granulate to obtain spherical material. S3. In a nitrogen atmosphere, the spherical material is placed in a tube furnace and held at 400°C for 40 minutes for pretreatment to obtain the structural material. S4. Place the structural material in a tube furnace and hold it at 1000℃ for 40 minutes for reduction carbonization. Then, ball mill it for 30 minutes and then add carbon in batches to obtain carbonized material. S5. Under a hydrogen atmosphere, the carbide material was placed in a molybdenum wire furnace and passivated at 1300℃ for 40 minutes. After crushing, nano-tungsten carbide was obtained, with a combined carbon content of 6.01%, a free carbon content of 0.14%, and a BET of 4.19 g / cm³. 3 .

[0037] Example 3

[0038] A method for preparing nano-tungsten carbide powder includes the following steps: S1. Tungsten oxide and carbon black are ball-milled and mixed for 240 minutes. After mixing, the mixture is sieved and dried to obtain a mixture. The molar ratio of tungsten oxide (WO3) to carbon black (C) is 1:3.2. S2. Place the mixture in an extruder and press it into strips. During the pressing process, add glucose as a structural agent. The mass of glucose is 1.5% of the total mass of tungsten oxide and carbon black. After pressing, centrifuge and granulate to obtain spherical material. S3. In a nitrogen atmosphere, the spherical material is placed in a tube furnace and held at 500°C for 30 minutes for pretreatment to obtain the structural material. S4. Place the structural material in a tube furnace and hold it at 900℃ for 60 minutes for reduction carbonization, then ball mill it for 30 minutes, and then add carbon in batches to obtain carbonized material. S5. Under a hydrogen atmosphere, the carbide material was placed in a molybdenum wire furnace and passivated at 1400℃ for 30 minutes. After crushing, nano-tungsten carbide was obtained, with a combined carbon content of 6.03%, a free carbon content of 0.14%, and a BET of 4.89 g / cm³. 3 .

[0039] Example 4

[0040] A method for preparing nano-tungsten carbide powder includes the following steps: S1. Tungsten oxide and carbon black are mixed with a plow for 300 minutes. After mixing, the mixture is sieved and dried to obtain a mixture. The molar ratio of tungsten oxide (WO3) to carbon black (C) is 1:3.0. S2. Place the mixture in an extruder and press it into strips. During the pressing process, add maltose as a structural agent. The mass of maltose is 2% of the total mass of tungsten oxide and carbon black. After pressing, centrifuge and granulate to obtain spherical material. S3. In a nitrogen atmosphere, the spherical material is placed in a rotary kiln and held at 600°C for 40 minutes for pretreatment to obtain the structural material; S4. Place the structural material in a tube furnace and hold it at 950℃ for 40 minutes for reduction carbonization, then ball mill it for 30 minutes, and then add carbon in batches to obtain carbonized material. S5. Under a hydrogen atmosphere, the carbide material was placed in a molybdenum wire furnace and passivated at 1400℃ for 30 minutes. After crushing, nano-tungsten carbide was obtained, with a combined carbon content of 6.04%, a free carbon content of 0.10%, and a BET of 3.79 g / cm³. 3 .

[0041] Example 5

[0042] A method for preparing nano-tungsten carbide powder includes the following steps: S1. Tungsten oxide and carbon black are mixed with a plow for 300 minutes. After mixing, the mixture is sieved and dried to obtain a mixture. The molar ratio of tungsten oxide (WO3) to carbon black (C) is 1:3.2. S2. Place the mixture in an extruder and press it into strips. During the pressing process, add glucose as a structural agent. The mass of glucose is 2% of the total mass of tungsten oxide and carbon black. After pressing, centrifuge and granulate to obtain spherical material. S3. In a nitrogen atmosphere, the spherical material is placed in a rotary kiln and held at 400°C for 20 minutes for pretreatment to obtain the structural material. S4. Place the structural material in a tube furnace and hold it at 900℃ for 20 minutes for reduction carbonization, then ball mill it for 30 minutes, and then add carbon in batches to obtain carbonized material. S5. Under a hydrogen atmosphere, the carbide material was placed in a molybdenum wire furnace and passivated at 1300℃ for 20 minutes. After crushing, nano-tungsten carbide was obtained, with a combined carbon content of 6.02%, a free carbon content of 0.15%, and a BET of 4.16 g / cm³. 3 .

[0043] Example 6

[0044] A method for preparing nano-tungsten carbide powder includes the following steps: S1. Tungsten oxide and carbon black are mixed with a plow for 300 minutes. After mixing, the mixture is sieved and dried to obtain a mixture. The molar ratio of tungsten oxide (WO3) to carbon black (C) is 1:3.2. S2. Place the mixture in an extruder and press it into strips. During the pressing process, add glucose as a structural agent. The mass of glucose is 2% of the total mass of tungsten oxide and carbon black. After pressing, centrifuge and granulate to obtain spherical material. S3. In a nitrogen atmosphere, the spherical material is placed in a rotary kiln and held at 600°C for 40 minutes for pretreatment to obtain the structural material; S4. The structural material is placed in a tube furnace and held at 1100℃ for 30 minutes for reduction carbonization. Then it is ball-milled and crushed for 30 minutes. Finally, it is batch carbonized to obtain carbonized material. S5. Under a hydrogen atmosphere, the carbide material was placed in a molybdenum wire furnace and passivated at 1500℃ for 20 minutes. After crushing, nano-tungsten carbide was obtained, with a combined carbon content of 6.09%, a free carbon content of 0.11%, and a BET of 4.06 g / cm³. 3 .

[0045] Comparative Example 1 A method for preparing nano-tungsten carbide powder includes the following steps: S1. 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. S2. The WO3 agglomerates obtained in step 1 are crushed using an air jet mill for 45 minutes at a flow rate of 180 m³ / min. 3 / h, gas pressure is 0.05MPa, crushed WO3 and high-purity carbon black are mixed by vertical plowing to obtain WO3 and carbon black mixture; S3. Using spray granulation technology and room temperature instant drying technology, the mixture in step S2 is spray granulated to obtain spherical material; S4. 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 time from feeding to discharging is 40 minutes, and a pre-carbonized material with a chemical composition of W+WC+W2C is obtained. S5. The pre-carburized material from step 4 is passivated in a reducing gas environment using a molybdenum wire furnace. After passivation, nano-tungsten carbide with complete and uniformly distributed grains is obtained. The passivation temperature is 1450℃, and the passivation time is 20 min. The final nano-tungsten carbide has a combined carbon content of 5.98%, a free carbon content of 0.16%, and a specific surface area of ​​3.98 m². 2 / g.

[0046] Comparative Example 2 A method for preparing nano-tungsten carbide powder includes the following steps: S1. Place the tungsten oxide into a cylindrical mold with a diameter of 100 mm and a height of 1000 mm, and press it into shape using an isostatic press at a pressure of 200 MPa for 5 minutes to obtain a tungsten oxide compact. S2. 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; S3. The obtained nano-tungsten oxide particles are 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. S4. The obtained nano-tungsten powder and carbon black are placed in a mixer and stirred for 6 hours to obtain a mixed powder, wherein the mass percentage of carbon black is 6.115%. The mixed powder is 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, a combined carbon content of 5.86%, a free carbon content of 0.13%, and a specific surface area of ​​4.14 m². 2 / g.

[0047] Comparative Example 3 The only difference between this comparative example and Example 1 is that in step S2, spherical material is obtained by spray granulation; the final obtained nano-tungsten carbide has a combined carbon content of 6.03%, a free carbon content of 0.22%, and a specific surface area of ​​3.88 m². 2 / g.

[0048] Comparative Example 4 The only difference between this comparative example and Example 1 is that step S3 is omitted; the spherical material is directly placed in a tube furnace and held at 950°C for 40 minutes for reduction carbonization, followed by ball milling for 30 minutes, and then batch carbonization is performed to obtain the carbonized material. The final obtained nano-tungsten carbide has a combined carbon content of 5.86%, a free carbon content of 0.26%, and a specific surface area of ​​3.59 m². 2 / g.

[0049] Results Analysis Figure 1 This image shows the microstructure of the spherical material surface after centrifugal granulation. The image reveals that the tungsten trioxide and carbon black particles are tightly bonded together, solving the problem of hollow and broken particles in spray-granulated materials, ensuring the reaction proceeds, and improving product consistency. The loose bulk density of the spray-granulated spherical material is 1.4~1.8 g / cm³. 3 The loose density of the spherical material in this application can reach 2.0~4.0 g / cm³. 3 .

[0050] Figure 2 The diagram shows the structure of the spherical material prepared by spray granulation in the comparative example. It can be seen from the figure that there are a large number of hollow structures, which will lead to breakage in the subsequent process. After breakage, tungsten trioxide and carbon black will separate, resulting in poor reaction effect. On the one hand, the reaction efficiency is reduced, and on the other hand, it is easy to have carbon-deficient phase and high free carbon.

[0051] Figure 3 The image shows the microstructure of the structural material prepared for the example. As can be seen from the image, by performing low-temperature pretreatment on the spherical material, a structural material with a large number of gas passages was obtained. These gas passages can improve the internal stress of the spherical material during the subsequent reaction process, thereby avoiding the breakage of the spherical material due to the generation of a large amount of gas, which would affect the reaction.

[0052] Figure 4 The figures show the microstructure of the products in the embodiments and comparative examples. It can be seen from the figures that the products prepared in the embodiments of this application have a uniform particle size distribution and significantly better consistency than those in the comparative examples. In the comparative examples, due to a series of problems pointed out in this application, the consistency of the products is poor, and obvious sintered blocks can also be observed.

[0053] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for preparing nano-tungsten carbide, characterized in that, Includes the following steps: S1. Mix tungsten oxide and carbon source, and sieve to obtain a mixture; S2. Add a structural agent to the mixture and press it into strips, then centrifuge and granulate it to obtain spherical material; S3. In a nitrogen atmosphere, the spherical material is pretreated by holding it at 400~600℃ for 20~40 minutes to obtain the structural material; S4. The structural material is reduced and carbonized, and then carbonized in batches to obtain carbonized material; S5. Passivate the carbide material and crush it to obtain the nano-tungsten carbide.

2. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S1, the tungsten oxide includes at least one of yellow tungsten, blue tungsten, purple tungsten, or brown tungsten; the carbon source includes carbon black or an organic carbon source; and the molar ratio of the tungsten oxide (calculated as WO3) to the carbon source (calculated as C) is 1:(2.7~3.2).

3. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S1, the specific surface area of ​​the tungsten oxide is 4.0~8.0 m². 2 / g.

4. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S2, the structural agent includes glucose and maltose, and the mass of the structural agent is 1% to 3% of the total mass of the tungsten oxide and the carbon source; the particle size of the spherical material is 2 to 5 mm.

5. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S2, the rotation speed of the centrifugal granulation is 20~60 rpm.

6. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S4, the temperature for reduction carbonization is 900~1100℃ and the time is 20~60min.

7. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S4, the carbonized material contains WC and W2C.

8. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S5, the passivation temperature is 1200~1500℃ and the time is 20~90min.

9. The method for preparing nano-tungsten carbide according to claim 1, characterized in that, In step S5, the nano-tungsten carbide has a combined carbon content ≥6.01%, a free carbon content ≤0.15%, and a specific surface area of ​​3.5~5.0 m². 2 / g.

10. A nano-tungsten carbide, characterized in that, It was prepared using the method for preparing nano-tungsten carbide according to any one of claims 1 to 9.

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