Preparation method for nano-tungsten carbide

Abstract

Provided is a preparation method for nano-tungsten carbide, comprising the following steps: pressing a tungsten oxide to obtain a tungsten oxide pressed blank; performing flame vaporization on the tungsten oxide pressed blank, and cooling and collecting the obtained tungsten oxide vapor to obtain nano-tungsten oxide particles; reducing the nano-tungsten oxide particles to obtain a nano-tungsten powder; and mixing the nano-tungsten powder with carbon, and carbonizing the obtained mixed powder to obtain nano-tungsten carbide. The provided preparation process is simple and convenient, yields high-quality nano-tungsten oxide and nano-tungsten carbide, and is suitable for industrial production.

Description

A preparation method of nano-tungsten carbide

[0001] This application claims priority to a Chinese patent application filed with the Patent Office of China on August 8, 2023, with application number CN202310986313.8 and invention name “A Method for Preparing Nano-Tungsten Carbide”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The invention belongs to the technical field of nanomaterials, and particularly relates to a method for preparing nano tungsten carbide. Background Art

[0003] Tungsten carbide is a key raw material for the production of cemented carbide, and its crystal size is a crucial factor influencing the performance of cemented carbide materials. When tungsten carbide crystals are nanoscale, ultrafine particles can significantly improve the hardness, flexural strength, and toughness of the resulting cemented carbide. Therefore, the preparation of nano-tungsten carbide is a key step in the preparation of high-performance cemented carbide.

[0004] Currently, the main methods for preparing nano-tungsten carbide are ammonium paratungstate decomposition and carbonization and mechanical alloying. The ammonium paratungstate decomposition and carbonization method utilizes a rotary kiln, which is prone to ring formation, slow decomposition, and complex. The mechanical alloying method, on the other hand, involves milling tungsten powder and carbon black in a high-energy ball mill to produce nano-sized tungsten carbide. While this method is simple, it requires lengthy milling times, consumes high energy, and can easily lead to high impurity levels, making it difficult to obtain high-quality tungsten carbide.

[0005] Therefore, there is an urgent need for a preparation method that is simple in process, low in cost and can produce high-quality nano-tungsten carbide.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to provide a method for preparing nano-tungsten carbide. The method provided by the present invention has simple process, low cost, and can obtain high-quality nano-tungsten carbide.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing nano-tungsten carbide, comprising the following steps:

[0010] Compressing the tungsten oxide to obtain a tungsten oxide compact;

[0011] flame gasifying the tungsten oxide compact, cooling and collecting the obtained tungsten oxide vapor to obtain nano tungsten oxide particles;

[0012] reducing the nano-tungsten oxide particles to obtain nano-tungsten powder;

[0013] The nano-tungsten powder and carbon are mixed, and the obtained mixed powder is carbonized to obtain the nano-tungsten carbide.

[0014] Preferably, the tungsten oxide includes one or more of yellow tungsten, blue tungsten, purple tungsten and brown tungsten.

[0015] Preferably, the pressing pressure is 180-240 MPa, and the holding time is 2-6 minutes.

[0016] Preferably, the temperature of the flame gasification is 1800-3000°C.

[0017] Preferably, the flame used in the flame gasification is formed by burning combustible gas;

[0018] The combustible gas includes one or more of acetylene, ethanol, methane, ammonia and hydrogen.

[0019] Preferably, the volume ratio of combustible gas to oxygen during combustion is 1:2 or 2:5.

[0020] Preferably, the cooling and collecting temperature is 0-10° C., and the time is 0.5-1.0 h.

[0021] Preferably, the cooling and collecting process includes: using a guide gas to introduce the obtained tungsten oxide vapor into a condensation collection device.

[0022] Preferably, the flow rate of the guide gas is 10 to 15 liters per minute.

[0023] Preferably, the specific surface area of ​​the nano-tungsten carbide is 4.01 to 4.37 m 2 / g.

[0024] Preferably, the reduction temperature is 600-700° C., and the holding time is 45-60 minutes.

[0025] Preferably, the reducing atmosphere comprises hydrogen, carbon monoxide or methane.

[0026] Preferably, the carbon is carbon black.

[0027] Preferably, the mass percentage of carbon in the mixed powder is 5.9-6.2%.

[0028] Preferably, the carbonization temperature is 700-1200° C., and the holding time is 45-90 minutes.

[0029] Preferably, the carbonization is carried out in a hydrogen atmosphere.

[0030] Preferably, the specific surface area of ​​the nano-tungsten carbide is 4.01 to 4.37 m 2 / g.

[0031] The present invention provides a method for preparing nano-tungsten carbide, comprising the following steps: pressing tungsten oxide to obtain a tungsten oxide compact; flame gasifying the tungsten oxide compact, cooling and collecting the resulting tungsten oxide vapor to obtain nano-tungsten oxide particles; reducing the nano-tungsten oxide particles to obtain nano-tungsten powder; mixing the nano-tungsten powder with carbon, and carbonizing the resulting mixed powder to obtain the nano-tungsten carbide. The preparation process provided by the present invention is simple, low-cost, and can produce high-quality nano-tungsten oxide and nano-tungsten carbide, making it suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a SEM image of nano-tungsten oxide obtained in Example 1;

[0033] FIG2 is a SEM image of nano-tungsten oxide obtained in Comparative Example 1;

[0034] FIG3 is a SEM image of the nano-tungsten carbide obtained in Example 1;

[0035] FIG4 is a SEM image of the nano-tungsten carbide obtained in Comparative Example 1. DETAILED DESCRIPTION

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

[0037] Compressing the tungsten oxide to obtain a tungsten oxide compact;

[0038] flame gasifying the tungsten oxide compact, cooling and collecting the obtained tungsten oxide vapor to obtain nano tungsten oxide particles;

[0039] reducing the nano-tungsten oxide particles to obtain nano-tungsten powder;

[0040] The nano-tungsten powder and carbon are mixed, and the obtained mixed powder is carbonized to obtain the nano-tungsten carbide.

[0041] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0042] The present invention compresses tungsten oxide to obtain a tungsten oxide compact.

[0043] In the present invention, the tungsten oxide preferably includes one or more of yellow tungsten, blue tungsten, purple tungsten and brown tungsten.

[0044] In the present invention, the pressing pressure is preferably 180-240 MPa, more preferably 190-230 MPa, more preferably 200-210 MPa; the holding time is preferably 2-6 min, more preferably 4-5 min. In the present invention, the size of the cylindrical mold used for pressing is preferably In a specific embodiment of the present invention, the size of the cylindrical mold is specifically or In the present invention, the pressing is preferably performed in an isostatic press.

[0045] After obtaining the tungsten oxide compact, the present invention performs flame gasification on the tungsten oxide compact, cools and collects the obtained tungsten oxide vapor, and obtains nano tungsten oxide particles.

[0046] In the present invention, the temperature of the flame gasification is preferably 1800-3000°C, more preferably 2000-2800°C, and even more preferably 2300-2500°C. In the present invention, the flame used in the flame gasification is formed by the combustion of a combustible gas; the combustible gas preferably includes one or more of acetylene, ethanol, methane, ammonia, and hydrogen. During the combustion, the volume ratio of the combustible gas to oxygen is preferably 1:2 or 2:5. In the present invention, the flow rate of the combustible gas is preferably 3-5 liters / minute.

[0047] In the present invention, the cooling and collection temperature is preferably 0-10°C, more preferably 1-8°C, and even more preferably 3-6°C; the duration is preferably 0.5-1.0 h, more preferably 0.6-0.9 h, and even more preferably 0.7-0.8 h. In the present invention, the cooling and collection process preferably includes: introducing the obtained tungsten oxide vapor into a condensation collection device using a guide gas; the substrate of the condensation collection device is preferably an aluminum alloy substrate; and the flow rate of the guide gas is preferably 10-15 liters / minute. In the present invention, the guide gas is preferably a protective gas, and even more preferably nitrogen.

[0048] In the present invention, the specific surface area of ​​the nano-tungsten oxide particles is preferably 16.12 to 19.05 m 2 / g.

[0049] After obtaining the nano-tungsten oxide particles, the present invention reduces the nano-tungsten oxide particles to obtain nano-tungsten powder.

[0050] In the present invention, the reduction temperature is preferably 600-700°C, more preferably 620-680°C, and more preferably 650-670°C; the holding time is preferably 45-60 minutes, more preferably 50-50 minutes. In the present invention, the reducing atmosphere preferably includes hydrogen, carbon monoxide, or methane.

[0051] After obtaining the nano tungsten powder, the present invention mixes the nano tungsten powder with carbon, and carbonizes the obtained mixed powder to obtain the nano tungsten carbide.

[0052] In the present invention, the carbon is preferably carbon black. In the present invention, the mass percentage of carbon in the mixed powder is preferably 5.9-6.2%, more preferably 6.0-6.1%. In the present invention, the mixing is preferably performed under stirring conditions, and the stirring time is preferably 0.5-8 hours. In the present invention, the mixing is preferably performed in a V-type mixer, a double-cone mixer, a three-dimensional mixer, or a ball mill mixer.

[0053] In the present invention, the carbonization temperature is preferably 700-1200°C, more preferably 800-1100°C, and more preferably 900-1000°C; the holding time is preferably 45-90 minutes, more preferably 50-80 minutes, and more preferably 60-70 minutes. In the present invention, the carbonization is preferably carried out in a hydrogen atmosphere. In the present invention, the carbonization is preferably carried out in a carbonization furnace.

[0054] In the present invention, the specific surface area of ​​the nano-tungsten carbide is preferably 4.01 to 4.37 m 2 / g.

[0055] In order to further illustrate the present invention, a method for preparing nano-tungsten carbide provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] Load the blue tungsten into the The cylindrical mold is pressed by an isostatic press at a pressure of 180 MPa and a holding time of 6 minutes to obtain a tungsten oxide compact;

[0058] The tungsten oxide pressed embryo was placed in a hydrogen-oxygen flame at 1800°C (where the volume ratio of hydrogen to oxygen was 1:2 and the flow rate of hydrogen was 3 liters / minute) to instantly vaporize the tungsten oxide to obtain tungsten oxide vapor. The obtained tungsten oxide vapor was introduced into a condensation collection device using nitrogen (flow rate of 11 liters / minute). The temperature of the condensation collection device was 0°C and the collection time was 0.5 hours. After the tungsten oxide homogeneously nucleated and grew, the tungsten oxide vapor was condensed to obtain nano-tungsten oxide particles. The specific surface area of ​​the obtained nano-tungsten oxide particles was 19.05 m 2 / g;

[0059] The obtained nano-tungsten oxide particles were reduced in a hydrogen reduction furnace at a temperature of 650°C for 1 hour to obtain nano-tungsten powder with complete and uniform grains.

[0060] 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 6.12%. The mixed powder was carbonized in a carbonization furnace at a temperature of 1050°C and a holding time of 70 minutes to obtain nano-tungsten carbide with complete and uniform grains and a specific surface area of ​​4.01m 2 / g.

[0061] Example 2

[0062] Place the yellow tungsten into a The cylindrical mold is pressed by an isostatic press at a pressure of 200 MPa and a holding time of 5 minutes to obtain a tungsten oxide compact;

[0063] The tungsten oxide pressed embryo was fed into an acetylene-oxygen flame at 2500°C (the volume ratio of acetylene to oxygen was 2:5, and the flow rate of acetylene was 3 L / min) to instantly vaporize the tungsten oxide to obtain tungsten oxide vapor. The obtained tungsten oxide vapor was introduced into a condensation collection device using nitrogen (flow rate was 15 L / min), wherein the temperature of the condensation collection device was 5°C and the receiving time was 1 hour. After the tungsten oxide homogeneously nucleated and grew, the tungsten oxide vapor was condensed to form nano-tungsten oxide particles. The specific surface area of ​​the obtained nano-tungsten oxide particles was 16.76 m 2 / g;

[0064] The obtained nano-tungsten oxide particles were reduced in a carbon monoxide reduction furnace at a temperature of 650°C for 45 minutes to obtain nano-tungsten powder with complete and uniform grains.

[0065] 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 carbonized in a carbonization furnace at a temperature of 900 ° C and a holding time of 90 minutes to obtain nano-tungsten carbide with complete and uniform grains and a specific surface area of ​​4.14 m 2 / g.

[0066] Example 3

[0067] Load brown tungsten into The cylindrical mold is pressed by an isostatic press at a pressure of 240 MPa and a holding time of 2 minutes to obtain a tungsten oxide compact;

[0068] The tungsten oxide pressed embryo was placed in a 3000°C hydrogen-oxygen flame (where the volume ratio of hydrogen to oxygen was 1:2 and the flow rate of hydrogen was 3 L / min) to instantly vaporize the tungsten oxide to obtain tungsten oxide vapor. The obtained tungsten oxide vapor was introduced into a condensation collection device using nitrogen (flow rate was 13 L / min). The temperature of the condensation collection device was 10°C and the receiving time was 1 hour. After the tungsten oxide homogeneously nucleated and grew, the tungsten oxide vapor was condensed to obtain nano-tungsten oxide particles. The specific surface area of ​​the obtained nano-tungsten oxide particles was 16.12 m 2 / g;

[0069] The obtained nano-tungsten oxide particles were reduced in a hydrogen reduction furnace at a temperature of 630°C for 50 minutes to obtain nano-tungsten powder with complete and uniform grains.

[0070] 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 6.12%. The mixed powder was carbonized in a carbonization furnace at a temperature of 1000°C and a holding time of 80 minutes to obtain nano-tungsten carbide with complete and uniform grains and a specific surface area of ​​4.37m 2 / g.

[0071] Comparative Example 1

[0072] 1.6 g of ammonium tungstate was fully mixed with 10 mL of 1.5 mol / L sulfuric acid and 25 mL of 0.5 mol / L ammonium sulfate. The mixture was added to a reactor and reacted at 150 °C for 6 h. The obtained product was repeatedly washed and placed in a muffle furnace and calcined at 600 °C for 6 h to obtain a specific surface area of ​​13.1 m 2 / g of nano tungsten trioxide;

[0073] Nano tungsten trioxide was reduced to obtain nano tungsten powder, which was then added to carbon black and mixed with carbon in a mixer (wherein the mass percentage of carbon black was 6.12%). The stirring time was 6 hours, and the obtained mixed powder was carbonized in a carbonization furnace at a temperature of 1000°C and a holding time of 80 minutes to obtain nano tungsten carbide with a specific surface area of ​​3.2 m 2 / g.

[0074] Comparative Example 2

[0075] 1.6 g of ammonium tungstate was fully mixed with 10 mL of 1.5 mol / L sulfuric acid and 25 mL of 0.5 mol / L ammonium sulfate. The mixture was added to a reactor and reacted at 200 °C for 6 h. The obtained product was repeatedly washed and placed in a muffle furnace and calcined at 650 °C for 6 h to obtain a specific surface area of ​​15.3 m 2 / g of nano tungsten trioxide;

[0076] Nano-tungsten trioxide was reduced to obtain nano-tungsten powder, which was then added to carbon black and mixed with carbon in a mixer (wherein the mass percentage of carbon black was 6.12%). The stirring time was 6 hours, and the obtained mixed powder was carbonized in a carbonization furnace at a temperature of 900°C and a holding time of 90 minutes to obtain nano-tungsten carbide with a specific surface area of ​​3.8 m 2 / g.

[0077] Performance Testing

[0078] Test Example 1

[0079] The nano-tungsten oxide obtained in Example 1 and Comparative Example 1 was examined by scanning electron microscopy, and the obtained SEM images are shown in Figures 1 and 2, wherein Figure 1 is Example 1 and Figure 2 is Comparative Example 1;

[0080] As can be seen from Figures 1 and 2, the nano-tungsten oxide prepared in Experimental Example 1 has good dispersibility, while the nano-tungsten oxide prepared in Comparative Example 1 has obvious agglomeration.

[0081] Test Example 2

[0082] The nano-tungsten carbide obtained in Example 1 and Comparative Example 1 was examined by scanning electron microscopy, and the obtained SEM images are shown in Figures 3 and 4, wherein Figure 3 is Example 1 and Figure 4 is Comparative Example 1;

[0083] As can be seen from Figures 3 and 4, the nano-tungsten carbide prepared in Experimental Example 1 has better uniformity, while the nano-tungsten carbide prepared in Comparative Example 1 has poorer uniformity.

[0084] Test Example 3

[0085] The content of impurities in the nano-tungsten carbide obtained in Example 1 was tested, and the test results are shown in Table 1;

[0086] Table 1 Impurity content of nano-tungsten carbide obtained in Example 1

[0087] It can be seen from Table 1 that the quality of the nano-tungsten carbide prepared in Example 1 has reached a relatively good level.

[0088] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing nano tungsten carbide, characterized in that: The following steps are involved: The tungsten oxide is pressed to obtain a tungsten oxide compact; The tungsten oxide compact is flame gasified, and the obtained tungsten oxide vapor is cooled and collected to obtain nano tungsten oxide particles; reducing the nano tungsten oxide particles to obtain nano tungsten powder; The nano tungsten powder and carbon are mixed, and the obtained mixed powder is carbonized to obtain the nano tungsten carbide.

2. The preparation method according to claim 1, characterized in that: The tungsten oxide includes one or more of yellow tungsten, blue tungsten, purple tungsten and brown tungsten.

3. The preparation method according to claim 1 or 2, characterized in that: The pressing pressure is 180-240 MPa, and the holding time is 2-6 min.

4. The preparation method according to claim 1, characterized in that: The temperature of the flame gasification is 1800-3000°C.

5. The preparation method according to claim 4, characterized in that: The flame used in the flame gasification is formed by burning combustible gas; The combustible gas includes one or more of acetylene, ethanol, methane, ammonia and hydrogen.

6. The preparation method according to claim 5, characterized in that: During the combustion, the volume ratio of the combustible gas to oxygen is 1:2 or 2:

5.

7. The preparation method according to claim 1, characterized in that: The cooling and collecting process is performed at a temperature of 0 to 10° C. and for a time of 0.5 to 1.0 h.

8. The preparation method according to claim 1, characterized in that: The cooling and collecting process includes: using a guide gas to introduce the obtained tungsten oxide vapor into a condensation collection device.

9. The preparation method according to claim 8, characterized in that: The flow rate of the guide gas is 10 to 15 liters per minute.

10. The preparation method according to claim 1, characterized in that: The specific surface area of ​​the nano tungsten oxide particles is 16.12-19.05 m 2 / g.

11. The preparation method according to claim 1, characterized in that: The reduction temperature is 600-700° C., and the insulation time is 45-60 minutes.

12. The preparation method according to claim 11, characterized in that: The reducing atmosphere includes hydrogen, carbon monoxide or methane.

13. The preparation method according to claim 1, characterized in that: The carbon is carbon black.

14. The preparation method according to claim 13, characterized in that: The mass percentage of carbon in the mixed powder is 5.9-6.2%.

15. The preparation method according to claim 1 or 14, characterized in that: The carbonization temperature is 700-1200° C., and the heat preservation time is 45-90 minutes.

16. The preparation method according to claim 15, characterized in that: The carbonization is performed in a hydrogen atmosphere.

17. The preparation method according to claim 1, characterized in that: The specific surface area of ​​the nano tungsten carbide is 4.01 to 4.37 m 2 / g.

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