Method for preparing tungsten carbide powder by sol-gel method

Abstract

The invention discloses a method for preparing tungsten carbide powder by a sol-gel method, which comprises the following steps: standing, aging and treating an aqueous solution containing a carbon source, a tungsten source and a gelling agent to obtain precursor powder; and the precursor powder is subjected to a reduction reaction, a carbonization reaction and a carbon removal reaction in a protective atmosphere, and the tungsten carbide powder is obtained. According to the preparation method, a tungsten source and a carbon source are premixed by adopting a gel method, the polymerization degree of a tungsten gel molecular network is accurately controlled through a gelling process, semi-coke is uniformly distributed on the tungsten gel molecular network, a tightly-combined dry gel block is formed after drying is finished, and a material layer is high in heat transfer speed, does not collapse and is uniform in temperature distribution in a calcining process; the synthesis temperature and time of the tungsten carbide powder are obviously reduced; the carbon and tungsten elements in the precursor network are uniformly distributed, so that the raw material conversion efficiency is improved, the product yield is improved, the number of raw materials which do not participate in the reaction is reduced, the subsequent pickling purification pressure is reduced, and the purity of the obtained product is higher than 99.8%.

Description

Technical Field

[0001] The invention belongs to the technical field of metal smelting, in particular to a method for preparing tungsten carbide powder by a sol-gel process. Background Art

[0002] Tungsten carbide-based cemented carbide has high hardness, high toughness, high melting point, good wear resistance and chemical stability, and is widely used in drill bits, cutting tools, metal processing and wear-resistant parts. At present, the preparation of tungsten carbide-based cemented carbide mainly adopts the process of powder metallurgy, using tungsten carbide powder as raw material, and is prepared by molding and sintering. In the preparation of cemented carbide, the particle size and purity of tungsten carbide powder have a great influence on the structure and performance of cemented carbide.

[0003] The industrial synthesis method of tungsten carbide powder is a two-step carbon thermal reduction method, which is as follows: 1. Tungsten oxide or ammonium metatungstate is used as a tungsten source and is reduced to metallic tungsten in a hydrogen atmosphere; 2. After the metallic tungsten and carbon black are evenly mixed, a tungsten carbide block is prepared at high temperature, and then crushed into tungsten carbide powder by vacuum high-energy ball milling. This process adopts the method of solid-phase powder mixing. The tungsten source and carbon source are prone to collapse and segregation during the calcination process. The raw material conversion rate is low, the product yield is low, and unconverted free carbon or metallic tungsten impurities are introduced. It needs to be vacuum crushed into powder for testing, carbon matching and re-burning; during the calcination process, the solid-phase powder has slow heat transfer and uneven temperature distribution, resulting in high carbonization reaction temperature, long cycle, and high per-ton capacity consumption. Existing tungsten carbide enterprises use expensive tungsten sources such as ammonium metatungstate and tungsten oxide. The high production cost results in mediocre corporate benefits, which has always been a pain point in the tungsten carbide smelting industry.

[0004] Chinese Patent 202310083164.4, a tungsten carbide powder and its preparation method and application, uses tungsten trioxide as a tungsten source and carbon black as a carbon source, and obtains tungsten carbide powder by secondary calcination and vacuum crushing. The calcination temperature of this method is as high as 2400℃, the calcination time exceeds 7h, and the obtained block carbide needs to be mixed and ball-milled to obtain the product. The process is long, energy consumption is high, and the cost is high.

[0005] Chinese patent 202310448322.1, an ultra-coarse uniform tungsten carbide powder and its preparation method, using tungsten trioxide as tungsten source, carbon black as carbon source, synergistically doped with metal Na, and sequentially through hydrogen reduction, high-energy crushing, airflow classification, three-stage carbonization, and high-energy ball milling to obtain tungsten carbide powder. The calcination temperature of this method is as high as 2190℃, and the calcination time is more than 14h. The introduction of alkali metal Na is highly corrosive to the equipment, and high-energy ball milling is prone to introduce other impurities. The product contains a small amount of W2C, which greatly affects its wear resistance, and has high comprehensive energy consumption and high cost. Most of the existing patents and literature use ammonium metatungstate or tungsten oxide as tungsten source and carbon black as carbon source to obtain tungsten carbide through hydrogen reduction and carburization reaction. The metallic tungsten obtained by carbon black and hydrogen reduction needs high-energy inert atmosphere ball milling, and the calcined carbide block needs high-energy ball milling. The whole process is complicated and energy-intensive, resulting in high production costs. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of high energy consumption and high cost in the prior art, and to provide a method for preparing tungsten carbide powder by a sol-gel method. The method uses cheap sodium tungstate and blue carbon as raw materials, and has the characteristics of short process flow, low calcination temperature and low energy consumption.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for preparing tungsten carbide powder by a sol-gel method comprises the following steps: The aqueous solution containing the carbon source, the tungsten source and the gelling agent is allowed to stand for aging and treatment to obtain a precursor powder; The precursor powder is subjected to reduction reaction, carbonization reaction and decarbonization reaction in a protective atmosphere to obtain tungsten carbide powder.

[0008] A further improvement of the present invention is that the tungsten source is sodium tungstate and the carbon source is blue carbon.

[0009] A further improvement of the present invention is that the purity of sodium tungstate is 60% to 80%, and the particle size of sodium tungstate is 60 mesh to 300 mesh; The semi-coke is semi-coke produced by pyrolysis in vertical furnace, conveyor bed, belt furnace or rotary kiln, with a particle size of 1μm~400μm and a fixed carbon content grade in the range of FC-1~FC-7.

[0010] A further improvement of the present invention is that the mass ratio of the carbon source, the tungsten source and water is (0.06-0.23):(0.33-0.55):1.

[0011] A further improvement of the present invention is that the gelling agent is an aqueous solution of ammonium salt and acid, and the total mass concentration of the ammonium salt and the acid in the gelling agent is 5% to 35%.

[0012] A further improvement of the present invention is that the ammonium salt is one of ammonium nitrate, ammonium chloride and ammonium sulfate, the acid is one of nitric acid, hydrochloric acid and sulfuric acid, the molar ratio of the ammonium salt to the acid is 1:1, and the mass ratio of the amount of the gelling agent to the aqueous solution is (0.2~1):1. A further improvement of the present invention is that the aging time is 4h~18h.

[0013] A further improvement of the present invention is that the atmosphere of the reduction reaction is Ar gas or N2, the temperature of the reduction reaction is 600°C~850°C, and the time of the reduction reaction is 1-2h.

[0014] A further improvement of the present invention is that the atmosphere of the carbonization reaction is Ar or N2, the temperature of the carbonization reaction is 1050°C~1400°C, and the time of the carbonization reaction is 2-4h.

[0015] A further improvement of the present invention is that the atmosphere of the decarbonization reaction is an Ar / H2 mixed gas or an N2 / H2 mixed gas, wherein the volume fraction of H2 in the mixed gas is 0.5% to 15%, and the decarbonization reaction time is 0.5h to 1h.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts the gel method to pre-mix the tungsten source and the carbon source, and accurately controls the degree of polymerization of the tungsten gel molecular network through the gelation process, so that the blue carbon is evenly distributed on the tungsten gel link network, and a tightly bound dry gel block is formed after drying. During the calcination process, the material layer has fast heat transfer, no collapse, and uniform temperature distribution, which significantly reduces the synthesis temperature and time of tungsten carbide powder; the uniform distribution of carbon tungsten elements in the precursor network improves the raw material conversion efficiency, the product yield is high, and the amount of raw materials not participating in the reaction is reduced, and the subsequent acid washing and purification pressure is reduced. The purity of the obtained product is higher than 99.8%, which meets the national standard tungsten carbide powder technical indicators. The raw materials used in the present invention are industrial sodium tungstate and industrial blue carbon. The product is cheap and easy to obtain due to its high impurity content. The core function of the gelling agent is not only to form tungsten gel, but also to remove the raw material impurities for the first time, reduce the corrosion pressure of alkali metals on the calcining furnace, and extend the service life of the equipment. The present invention adopts the gel method, so that the subsequent carbonization reaction temperature is low, and there is no need to add high-energy crushing equipment, which can significantly reduce the equipment investment cost and energy consumption cost. The product has a high yield, with a tungsten atom conversion rate of over 99.5%, which complies with the "Standard Conditions for Tungsten Industry". The product has high purity and meets the national standard requirements for tungsten carbide powder. The raw material cost is 9.7% lower than the traditional carbon thermal reduction method, and the product does not require high-energy ball milling to obtain the required particle size powder, which has good economic benefits.

[0017] Furthermore, the purity of the raw materials used in the present invention has little effect on the purity and particle size of the product. The particle size and purity of the tungsten carbide powder can be directionally regulated by the temperature and time of the reduction reaction, carbonization reaction and decarbonization reaction. As the reaction temperature and time increase, the purity and particle size of the tungsten carbide powder slowly increase. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the drawings required for describing the specific implementation or the prior art will be briefly introduced below. Obviously, the drawings described below are only one implementation of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work. Figure 1 The XRD pattern of tungsten carbide prepared in Example 3 of the present invention; Figure 2 This is a particle size distribution diagram of the finished tungsten carbide powder prepared in Example 3 of the present invention; Figure 3 The present invention is a flow chart of a method for preparing tungsten carbide powder by a sol-gel method. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0020] See also Figure 3 The present invention discloses a method for preparing tungsten carbide powder by sol-gel method, which uses blue carbon as carbon source and sodium tungstate as tungsten source; prepares carbon and tungsten uniformly mixed sol by titration of gelling agent, washes and dries the precursor in turn, and prepares tungsten carbide powder with a particle size of 1 μm to 100 μm in a calcining furnace in one step, and the powder purity is ≥99.8%. The specific steps are as follows: (1) Sodium tungstate is used as the tungsten source and blue carbon is used as the carbon source. The tungsten source and the carbon source are prepared into a precursor aqueous solution. The precursor aqueous solution is titrated into the gelling agent at a certain speed, accompanied by vigorous stirring, and allowed to stand for aging. The precursor powder is then filtered, pickled, washed with water and dried in sequence to obtain the precursor powder.

[0021] Among them, the purity of sodium tungstate is 60%~80%, and the particle size of sodium tungstate powder is 60 mesh~300 mesh. The types of semi-coke are vertical furnace pyrolysis semi-coke, conveyor bed pyrolysis semi-coke, belt furnace pyrolysis or rotary kiln pyrolysis semi-coke, the particle size specification is between 1μm~400μm, and the fixed carbon content level is in the range of FC-1~FC-7. The mass ratio of carbon source, tungsten source and water in the precursor aqueous solution is (0.06~0.23): (0.33~0.55): 1. The gelling agent is an aqueous solution of ammonium salt and acid, the ammonium salt is one of ammonium nitrate, ammonium chloride and ammonium sulfate, the acid is one of nitric acid, hydrochloric acid and sulfuric acid, the molar ratio of one of ammonium nitrate, ammonium chloride and ammonium sulfate to one of nitric acid, hydrochloric acid and sulfuric acid is 1:1, the total mass concentration of ammonium salt and acid in the gelling agent is 5%~35%, the mass ratio of the amount of gelling agent to the precursor aqueous solution is (0.2~1):1, and the aging time is 4h~18h. The pickling process uses dilute nitric acid or dilute hydrochloric acid with a mass fraction of 1%~5%, and the number of pickling and water washing is 1~3 times and 2~5 times respectively. Drying uses infrared drying, blast drying, vacuum freeze drying or microwave drying.

[0022] (2) The precursor powder is placed in a calcining furnace and subjected to a one-step reduction reaction, a carbonization reaction and a decarbonization reaction in a protective atmosphere to obtain a high-purity tungsten carbide powder with a particle size range of 1 μm-100 μm.

[0023] Among them, the reduction reaction, the atmosphere is Ar gas or N2, the reduction reaction temperature is 600℃~850℃, and the reduction reaction time is 1-2h; Carbonization reaction, the atmosphere is Ar or N2, the temperature of the carbonization reaction is 1050℃~1400℃, and the time of the carbonization reaction is 2-4h; For the decarbonization reaction, the atmosphere is an Ar / H2 mixed gas or a N2 / H2 mixed gas, wherein the volume fraction of H2 in the mixed gas is 0.5% to 15%, the temperature of the decarbonization reaction is 650-800°C, and the time of the decarbonization reaction is 0.5h to 1h.

[0024] The following are specific embodiments.

[0025] Example 1 A method for preparing tungsten carbide powder by a sol-gel method comprises the following steps: (1) Sodium tungstate is used as the tungsten source, wherein the purity of sodium tungstate is 80%, and the particle size of sodium tungstate is 80-90 mesh; vertical furnace pyrolysis blue carbon is used as the carbon source, the blue carbon particle size specification is 100μm, and the fixed carbon content grade is FC-3 (86%-88%); sodium tungstate and blue carbon are mixed and dissolved in water and stirred thoroughly to obtain a precursor aqueous solution, wherein the mass ratio of blue carbon: sodium tungstate: water is 0.1:0.35:1. The precursor aqueous solution is slowly titrated into the gelling agent and allowed to stand for aging; wherein the gelling agent is an aqueous solution prepared by hydrochloric acid and ammonium nitrate, the molar ratio of hydrochloric acid to ammonium nitrate is 1:1, the total mass concentration of ammonium nitrate and hydrochloric acid in the gelling agent is 10%, the mass ratio of the gelling agent to the precursor solution is 0.3:1, and the aging time is 12h. The precursor powder is obtained by positive pressure filtration, acid washing, water washing and air drying. The acid washing is performed twice with hydrochloric acid having a mass concentration of 3.5%, and the pure water is used for washing twice.

[0026] (2) The precursor is placed in a calcination furnace. The calcination process is divided into three stages: 1. Reduction stage: reduction at 800°C for 1 hour under Ar atmosphere to obtain metallic tungsten; 2. Calcination stage: carbonization at 1200°C for 2 hours under Ar atmosphere to obtain tungsten carbide; 3. Decarbonization stage: decarbonization at 800°C for 1 hour under Ar / H2 mixed atmosphere (hydrogen gas volume fraction is 5%) to obtain refined tungsten carbide, wherein the average particle size of tungsten carbide powder is 12.51μm, XRD shows no impurity crystals, and the purity is 99.83%.

[0027] Example 2 A method for preparing tungsten carbide powder by a sol-gel method comprises the following steps: (1) Sodium tungstate is used as the tungsten source, wherein the purity of sodium tungstate is 60% and the particle size of sodium tungstate is 180-200 mesh; belt furnace pyrolysis semi-coke is used as the carbon source, the semi-coke particle size specification is 200μm, and the fixed carbon content grade is FC-6 (80%-82%); sodium tungstate and semi-coke are mixed and dissolved in water and stirred thoroughly to obtain a precursor aqueous solution, wherein the mass ratio of semi-coke: sodium tungstate: water is 0.15:0.4:1. The precursor aqueous solution is slowly titrated into the gelling agent and allowed to stand for aging; wherein the gelling agent is an aqueous solution prepared by sulfuric acid and ammonium sulfate, the molar ratio of sulfuric acid to ammonium sulfate is 1:1, the total mass concentration of sulfuric acid and ammonium sulfate in the gelling agent is 22%, the mass ratio of the gelling agent to the precursor solution is 0.2:1, and the aging time is 8h. The precursor powder is obtained by negative pressure filtration, acid washing, water washing and infrared drying. The acid washing is performed once with 5% nitric acid and the pure water is used for three times.

[0028] (2) The precursor is placed in a calcination furnace. The calcination process is divided into three stages: 1. Reduction stage: reduction at 650°C for 1 hour under Ar atmosphere to obtain metallic tungsten; 2. Calcination stage: carbonization at 1400°C for 2 hours under Ar atmosphere to obtain tungsten carbide; 3. Decarbonization stage: decarbonization at 800°C for 1 hour under Ar / H2 mixed atmosphere (hydrogen gas volume fraction is 5%) to obtain refined tungsten carbide, wherein the average particle size of tungsten carbide powder is 16.91μm, XRD shows no impurity crystals, and the purity is 99.91%.

[0029] Example 3 A method for preparing tungsten carbide powder by a sol-gel method comprises the following steps: (1) Sodium tungstate is used as the tungsten source, wherein the purity of sodium tungstate is 70% and the particle size of sodium tungstate is 100-120 mesh; rotary kiln pyrolysis blue coke is used as the carbon source, the blue coke particle size specification is 300μm, and the fixed carbon content grade is FC-4 (84%-86%); sodium tungstate and blue coke are mixed and dissolved in water and stirred thoroughly to obtain a precursor aqueous solution, wherein the mass ratio of blue coke: sodium tungstate: water is 0.12:0.45:1. The precursor aqueous solution is slowly titrated into the gelling agent and allowed to stand for aging; wherein the gelling agent is an aqueous solution prepared by hydrochloric acid and ammonium nitrate, the molar ratio of hydrochloric acid to ammonium nitrate is 1:1, the total mass concentration of hydrochloric acid and ammonium nitrate in the gelling agent is 12%, the mass ratio of the gelling agent to the precursor solution is 0.35:1, and the aging time is 10h. The precursor powder was obtained by positive pressure filtration, acid washing, water washing and freeze drying. 2.5% hydrochloric acid was used for one acid washing and pure water was used for three water washings.

[0030] (2) The precursor is placed in a calcining furnace. The calcination process is divided into three stages: 1. Reduction stage: reduction at 850°C for 1.5 hours under Ar atmosphere to obtain metallic tungsten; 2. Calcination stage: carbonization at 1050°C for 2.5 hours under Ar atmosphere to obtain tungsten carbide; 3. Decarbonization stage: decarbonization at 800°C for 0.5 hours under Ar / H2 mixed atmosphere (hydrogen gas volume fraction is 0.5%) to obtain refined tungsten carbide, wherein the average particle size of tungsten carbide powder is 14.33μm, XRD shows no impurity crystals, and the purity is 99.88%.

[0031] See also Figure 1 It can be seen that the characteristic peaks and five-finger peak spectrum of the synthesized tungsten carbide powder of the present invention at 31.5°, 35.6°, 48.3°, 64.0°, 65.8°, 73.1°, 75.5°77.1° and 84.1° are consistent with those in the standard card PDF#10-1315 (001) (100) (101) (110) (002) (111) (200) (102) (201), which is a pure tungsten carbide crystal phase with no impurities and no impurity peaks of free carbon and ditungsten carbide.

[0032] See also Figure 2 It can be seen that the particle size D10 of the synthesized tungsten carbide powder of the present invention is 2.46 μm, D50 is 14.33 μm, and D90 is 47.10 μm, and the particle size classification can be directly carried out by the pneumatic classification equipment.

[0033] Example 4 A method for preparing tungsten carbide powder by a sol-gel method comprises the following steps: (1) Sodium tungstate is used as the tungsten source, wherein the purity of sodium tungstate is 65% and the particle size of sodium tungstate is 60-100 mesh; conveyor bed pyrolysis blue carbon is used as the carbon source, the blue carbon particle size specification is 1-20μm, and the fixed carbon content grade is FC-1 (90%); sodium tungstate and blue carbon are mixed and dissolved in water and stirred thoroughly to obtain a precursor aqueous solution, wherein the mass ratio of blue carbon: sodium tungstate: water is 0.06:0.33:1. The precursor aqueous solution is slowly titrated into the gelling agent and allowed to stand for aging; wherein the gelling agent is an aqueous solution prepared by hydrochloric acid and ammonium nitrate, the molar ratio of hydrochloric acid to ammonium nitrate is 1:1, the total mass concentration of hydrochloric acid and ammonium nitrate in the gelling agent is 5%, the mass ratio of the gelling agent to the precursor solution is 1:1, and the aging time is 4h. The precursor powder is obtained by positive pressure filtration, acid washing, water washing and freeze drying. The acid washing is performed once with 1% hydrochloric acid and the pure water is used for three times.

[0034] (2) Place the precursor in a calcining furnace. The calcination process is divided into three stages: 1. Reduction stage: reduction at 600°C for 2 hours in a N2 atmosphere to obtain metallic tungsten; 2. Calcination stage: carbonization at 1300°C for 3 hours in a N2 atmosphere to obtain tungsten carbide; 3. Decarbonization stage: decarbonization at 650°C for 1 hour in an Ar / H2 mixed atmosphere (hydrogen gas volume fraction is 15%) to obtain refined tungsten carbide.

[0035] Example 5 A method for preparing tungsten carbide powder by a sol-gel method comprises the following steps: (1) Sodium tungstate is used as tungsten source, wherein the purity of sodium tungstate is 25% and the particle size of sodium tungstate is 370-400 mesh; conveyor bed pyrolysis blue carbon is used as carbon source, the blue carbon particle size specification is 400μm, and the fixed carbon content grade is FC-7 (78%-80%); sodium tungstate and blue carbon are mixed and dissolved in water and stirred thoroughly to obtain a precursor aqueous solution, wherein the mass ratio of blue carbon: sodium tungstate: water is 0.23:0.35:1. The precursor aqueous solution is slowly titrated into the gelling agent and allowed to stand for aging; wherein the gelling agent is an aqueous solution prepared by hydrochloric acid and ammonium nitrate, the molar ratio of hydrochloric acid to ammonium nitrate is 1:1, the total mass concentration of hydrochloric acid and ammonium nitrate in the gelling agent is 35%, the mass ratio of the gelling agent to the precursor solution is 0.7:1, and the aging time is 18h. The precursor powder is obtained by positive pressure filtration, acid washing, water washing and freeze drying. The acid washing is performed once with 2% hydrochloric acid and the pure water is used for three times.

[0036] (2) Place the precursor in a calcining furnace. The calcination process is divided into three stages: 1. Reduction stage: reduction at 700°C for 1.5 hours under N2 atmosphere to obtain metallic tungsten; 2. Calcination stage: carbonization at 1000°C for 4 hours under N2 atmosphere to obtain tungsten carbide; 3. Decarbonization stage: decarbonization at 700°C for 0.7 hours under Ar / H2 mixed atmosphere (hydrogen gas volume fraction is 10%) to obtain refined tungsten carbide.

[0037] The purity, particle size and crystal phase of the tungsten carbide powder prepared in Examples 1-3 are shown in Table 1.

[0038] Table 1 Purity, particle size and crystal phase of tungsten carbide products obtained during the implementation of the present invention

[0039] It can be seen from Table 1 that the tungsten carbide prepared by the present invention has high purity and a particle size of 12.51-16.91 μm.

[0040] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A method for preparing tungsten carbide powder by a sol-gel method, characterized in that: The following steps are involved: The aqueous solution containing the carbon source, the tungsten source and the gelling agent is allowed to stand for aging and treatment to obtain a precursor powder; The precursor powder is subjected to reduction reaction, carbonization reaction and decarbonization reaction in a protective atmosphere to obtain tungsten carbide powder.

2. The method for preparing tungsten carbide powder by sol-gel method according to claim 1, characterized in that: The tungsten source is sodium tungstate, and the carbon source is blue carbon.

3. The method for preparing tungsten carbide powder by sol-gel method according to claim 2, characterized in that: The purity of sodium tungstate is 60%~80%, and the particle size of sodium tungstate is 60 mesh~300 mesh; The semi-coke is semi-coke produced by pyrolysis in vertical furnace, conveyor bed, belt furnace or rotary kiln, with a particle size of 1μm~400μm and a fixed carbon content grade in the range of FC-1~FC-7.

4. The method for preparing tungsten carbide powder by sol-gel method according to claim 1, characterized in that: The mass ratio of carbon source, tungsten source and water is (0.06~0.23):(0.33~0.55):

1.

5. The method for preparing tungsten carbide powder by sol-gel method according to claim 1, characterized in that: The gelling agent is an aqueous solution of ammonium salt and acid, and the total mass concentration of the ammonium salt and the acid in the gelling agent is 5% to 35%.

6. The method for preparing tungsten carbide powder by sol-gel method according to claim 5, characterized in that: The ammonium salt is one of ammonium nitrate, ammonium chloride and ammonium sulfate, the acid is one of nitric acid, hydrochloric acid and sulfuric acid, the molar ratio of the ammonium salt to the acid is 1:1, and the mass ratio of the amount of the gelling agent to the aqueous solution is (0.2~1):

1.

7. The method for preparing tungsten carbide powder by sol-gel method according to claim 5, characterized in that: The aging time is 4h~18h.

8. The method for preparing tungsten carbide powder by sol-gel method according to claim 1, characterized in that: The atmosphere of the reduction reaction is Ar gas or N2, the temperature of the reduction reaction is 600°C~850°C, and the time of the reduction reaction is 1-2h.

9. The method for preparing tungsten carbide powder by sol-gel method according to claim 1, characterized in that: The atmosphere of the carbonization reaction is Ar or N2, the temperature of the carbonization reaction is 1050°C~1400°C, and the time of the carbonization reaction is 2-4h.

10. The method for preparing tungsten carbide powder by sol-gel method according to claim 1, characterized in that: The atmosphere of the decarbonization reaction is an Ar / H2 mixed gas or a N2 / H2 mixed gas, wherein the volume fraction of H2 in the mixed gas is 0.5%~15%, and the decarbonization reaction time is 0.5h~1h.

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