A method for producing vanadium carbide

Abstract

The application discloses a preparation method of vanadium carbide, which comprises the following steps: uniformly mixing vanadium-containing raw materials and carbonaceous powder, then adding a binder, ball milling for 1-3 hours to obtain a mixture; pressing and forming the mixture to obtain a green body; performing high-temperature solid-phase reaction on the green body under vacuum, inert or reducing gas conditions; and cooling the green body to room temperature under vacuum, inert or reducing gas conditions to obtain the vanadium carbide. The vanadium-containing raw materials and the carbonaceous powder are firstly mixed, then the binder is added, and the ball mill is used for the second mixing, so that the vanadium-containing raw materials and the carbonaceous powder are more uniformly mixed. The material is compacted before calcination, the contact area of the vanadium-containing raw materials and the carbonaceous powder is effectively increased, the diffusion distance between the particles of the two reactants is reduced, the reaction is promoted, the yield and the purity of the obtained product are high, the process is simple, the energy consumption is low, and the method is suitable for large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy, and more specifically, this invention relates to a method for preparing vanadium carbide. Background Technology

[0002] Vanadium carbide (VC) possesses a variety of properties, including high chemical resistance, high hardness, high melting point, and good electrothermal properties, making it widely used in steel metallurgy, cemented carbide, electronic products, catalysts, and high-temperature coating materials. Literature reports that the thermodynamic stability of various carbide inhibitors determines their inhibitory effect, with the order of inhibitory effect being: VC > Mo₂C > Cr₃C₂ > NbC > TaC > TiC > ZrC. The addition of VC can also act as a hard phase, significantly improving the hardness and lifespan of cemented carbides, while reducing their saturation magnetization, remanence, coercivity, magnetic energy product, permeability, and Curie temperature, thus producing non-magnetic alloys. In the preparation of cemented carbides, VC is an effective additive for inhibiting WC grain growth. During the sintering of WC-Co cemented carbides, the presence of VC reduces the solubility of WC in the Co binder phase, inhibiting WC grain growth through a dissolution-precipitation process.

[0003] Currently, vanadium carbide is mainly synthesized by reducing vanadium pentoxide or vanadium trioxide with coke. Chinese patent CN108002383A uses vanadium pentoxide and polyethylene powder as raw materials, and involves mixing, granulation, crushing, and drying, followed by two calcinations under vacuum. The first calcination temperature is 830–980℃, while vanadium pentoxide volatilizes significantly above 700℃, resulting in low product yield and insufficient purity. Furthermore, the first calcination requires cooling, followed by a second calcination at 1200–1380℃, leading to high energy consumption. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0005] To achieve these objectives and other advantages of the present invention, a method for preparing vanadium carbide is provided, comprising the following steps:

[0006] Step 1: Mix the vanadium-containing raw materials and carbonaceous powder evenly, then add the binder and ball mill to obtain the mixture.

[0007] Step 2: Press the mixture obtained in Step 1 into a compact shape;

[0008] Step 3: The compact is subjected to a high-temperature solid-state reaction under vacuum, inert or reducing gas conditions. After the reaction is completed, it is cooled to room temperature under vacuum, inert or reducing gas conditions to obtain vanadium carbide.

[0009] Preferably, in step one, the vanadium-containing raw material is at least one of vanadium pentoxide, vanadium trioxide, and metallic vanadium powder; the carbonaceous powder is at least one of graphite, carbon black, activated carbon, and organic carbon; and the molar ratio of V in the vanadium-containing raw material to C in the carbonaceous powder is 1:2 to 5.

[0010] Preferably, in step one, the mixing of vanadium-containing raw materials and carbonaceous powder is carried out in a dual-motion mixer, planetary mixer, three-dimensional mixer, or V-type mixer.

[0011] Preferably, in step one, the binder is at least one of carboxypropyl cellulose, ethyl cellulose, and polyvinylpyrrolidone; the amount of binder added is 1 to 3% of the total mass of the vanadium-containing raw material and carbonaceous powder.

[0012] Preferably, in step one, the specific conditions for ball milling are as follows: the ball milling time is 1 to 3 hours, the ball milling medium is at least one of methanol, anhydrous ethanol, isopropanol, and propylene glycol, the liquid-to-solid ratio is 3 to 5:1, the grinding balls are tungsten carbide balls or zirconium oxide balls, and the ball-to-material ratio is 5 to 15:1.

[0013] Preferably, in step two, the pressure parameter for pressing is 10–50 MPa.

[0014] Preferably, in step three, the vacuum level is 6–8 × 10⁻⁶. -3 Pa; the inert gas is one or a combination of argon and helium; the reducing gas is one or a combination of carbon monoxide and hydrogen.

[0015] Preferably, in step three, the specific method for the high-temperature solid-phase reaction is as follows: first, raise the temperature to 500-700℃ and hold for 2-5 hours, then raise the temperature to 1100-1500℃ and hold for 2-6 hours.

[0016] Preferably, the process further includes: placing the pressed blank obtained in step two into a graphite crucible of a plasma arc furnace, first introducing argon gas to purge the air, then introducing a mixture of argon gas and carbon monoxide, turning on the plasma arc to heat up and react for 2-4 hours to obtain vanadium carbide.

[0017] Preferably, the plasma arc furnace has a voltage of 30–100V, a current of 200–500A, and a temperature of 600–1500℃; the partial pressure of argon gas is 0.1–0.5MPa, and the partial pressure of carbon monoxide gas is 1–5MPa.

[0018] Preferably, in step one, a vacuum acoustic resonance mixer is used to mix the vanadium-containing raw material and the carbonaceous powder.

[0019] Preferably, the frequency of the vacuum acoustic resonance is 40-60Hz, the acceleration is 50-80g, and the vacuum degree is 50-150Pa.

[0020] The present invention provides at least the following beneficial effects: First, a vanadium-containing raw material and carbonaceous powder are mixed once, then a binder is added, and a second mixing is performed using a ball mill, resulting in a more uniform mixture of the vanadium-containing raw material and carbonaceous powder. Before calcination, the material is compacted, effectively increasing the contact area between the vanadium-containing raw material and the carbonaceous powder, reducing the diffusion distance between the two reactant particles, promoting the reaction, and resulting in a high yield and high purity of vanadium carbide. The calcination process requires no cooling, has low energy consumption, and is simple, making it suitable for large-scale applications. Furthermore, the present invention uses vacuum acoustic resonance to mix the vanadium-containing raw material and carbonaceous powder, resulting in higher mixing efficiency and more uniform mixing, further promoting the reaction and improving the purity of the vanadium carbide. The present invention utilizes a plasma arc furnace for heating, resulting in higher heating efficiency, shorter calcination time, lower energy consumption, and a more complete reaction between the vanadium-containing raw material and the carbonaceous powder, leading to higher purity vanadium carbide.

[0021] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0023] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0024] Example 1

[0025] A method for preparing vanadium carbide includes the following steps:

[0026] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a double-motion mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1. The grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0027] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0028] Step 3: Place the pressed billet into a high-temperature vacuum furnace, at a vacuum degree of 6.7 × 10⁻⁶. -3 Under the conditions of Pa, the temperature was first raised to 650℃ and held for 4 hours, then raised to 1100℃ and held for 2 hours, and then cooled to room temperature under vacuum to obtain vanadium carbide with a purity of 99.29%.

[0029] Example 2

[0030] A method for preparing vanadium carbide includes the following steps:

[0031] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a double-motion mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1. The grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0032] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0033] Step 3: Place the pressed billet into a high-temperature vacuum furnace, at a vacuum degree of 6.7 × 10⁻⁶. -3 Under the conditions of Pa, the temperature was first raised to 650℃ and held for 4 hours, then raised to 1250℃ and held for 4 hours, and then cooled to room temperature under vacuum to obtain vanadium carbide with a purity of 98.41%.

[0034] Example 3

[0035] A method for preparing vanadium carbide includes the following steps:

[0036] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a double-motion mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1. The grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0037] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0038] Step 3: Place the pressed billet into a high-temperature vacuum furnace, at a vacuum degree of 6.7 × 10⁻⁶. -3 Under the conditions of Pa, the temperature was first raised to 650℃ and held for 4 hours, then raised to 1300℃ and held for 6 hours, and then cooled to room temperature under vacuum to obtain vanadium carbide with a purity of 99.72%.

[0039] Example 4

[0040] A method for preparing vanadium carbide includes the following steps:

[0041] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a double-motion mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1. The grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0042] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0043] Step 3: Place the pressed billet into a high-temperature vacuum furnace. In a carbon monoxide atmosphere, first heat it to 650°C and hold it for 4 hours, then heat it to 1100°C and hold it for 2 hours. Cool it to room temperature in a carbon monoxide atmosphere to obtain vanadium carbide with a purity of 99.43%.

[0044] Example 5

[0045] A method for preparing vanadium carbide includes the following steps:

[0046] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a double-motion mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1. The grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0047] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0048] Step 3: Place the pressed billet into a high-temperature vacuum furnace. In an argon atmosphere, first heat it to 650°C and hold it for 4 hours, then heat it to 1100°C and hold it for 2 hours. Cool it to room temperature in an argon atmosphere to obtain vanadium carbide with a purity of 99.35%.

[0049] Example 6

[0050] A method for preparing vanadium carbide includes the following steps:

[0051] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a double-motion mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1. The grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0052] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0053] Step 3: Place the pressed billet into the graphite crucible of the plasma arc furnace. First, argon gas is introduced to purge the air, then argon gas and carbon monoxide are introduced. The partial pressure of argon gas is 0.3 MPa, and the partial pressure of carbon monoxide gas is 3 MPa. Set the voltage of the plasma arc furnace to 30V and the current to 250A. Turn on the plasma arc and heat to 650℃, hold for 2 hours. Then set the voltage of the plasma arc furnace to 50V and the current to 300A, heat to 1100℃, hold for 1 hour, and cool to room temperature under the atmosphere of argon and carbon monoxide to obtain vanadium carbide with a purity of 99.89%.

[0054] This embodiment utilizes a plasma arc furnace for heating, with the plasma arc as the heat source, resulting in higher heating efficiency, effectively shortening the calcination time, and allowing for a more complete reaction between vanadium pentoxide and graphite, leading to higher purity vanadium carbide.

[0055] Example 7

[0056] A method for preparing vanadium carbide includes the following steps:

[0057] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a vacuum acoustic resonance mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The vacuum acoustic resonance mixing frequency is 45Hz, the acceleration is 70g, and the vacuum degree is 100Pa. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1, and the grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0058] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0059] Step 3: Place the pressed blank into a high-temperature vacuum furnace, at a vacuum degree of 6.7 × 10⁻⁶. -3 Under the conditions of Pa, the temperature was first raised to 650℃ and held for 4 hours, then raised to 1100℃ and held for 2 hours, and then cooled to room temperature under vacuum to obtain vanadium carbide with a purity of 99.78%.

[0060] This embodiment utilizes vacuum acoustic resonance to mix vanadium-containing raw materials and carbonaceous powder more uniformly, further promoting the reaction of materials. Compared with Example 1, the vanadium carbide obtained has higher purity.

[0061] Example 8

[0062] A method for preparing vanadium carbide includes the following steps:

[0063] Step 1: Add 182g of vanadium pentoxide and 60g of graphite powder to a vacuum acoustic resonance mixer and mix evenly. Then add 3g of polyvinylpyrrolidone and ball mill for 2 hours to obtain a mixture. The vacuum acoustic resonance mixing frequency is 45Hz, the acceleration is 70g, and the vacuum degree is 100Pa. The ball milling medium is anhydrous ethanol with a liquid-to-solid ratio of 4:1, and the grinding balls are tungsten carbide balls with a ball-to-material ratio of 10:1.

[0064] Step 2: Press the mixture obtained in Step 1 into a compact with a pressure parameter of 15 MPa.

[0065] Step 3: Place the pressed billet into the graphite crucible of the plasma arc furnace. First, argon gas is introduced for venting, then argon gas and carbon monoxide are introduced, with the partial pressure of argon gas being 0.3 MPa and the partial pressure of carbon monoxide gas being 3 MPa. Set the voltage of the plasma arc furnace to 30V and the current to 250A. Turn on the plasma arc and heat to 650℃, hold for 2 hours, then set the voltage of the plasma arc furnace to 50V and the current to 300A, heat to 1100℃, hold for 1 hour, and cool to room temperature under the atmosphere of argon and carbon monoxide to obtain vanadium carbide with a purity of 99.93%.

[0066] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for preparing vanadium carbide, characterized in that, Includes the following steps: Step 1: Use a vacuum acoustic resonance mixer to mix vanadium-containing raw materials and carbonaceous powder evenly, then add a binder and ball mill to obtain a mixture; wherein, the binder is polyvinylpyrrolidone; the frequency of the vacuum acoustic resonance is 40~60Hz, the acceleration is 50~80g, and the vacuum degree is 50~150Pa; the vanadium-containing raw material is vanadium pentoxide; the specific conditions for ball milling are: ball milling time is 1~3h, the ball milling medium is at least one of methanol, anhydrous ethanol, isopropanol, and propylene glycol, the liquid-to-solid ratio is 3~5:1, the grinding balls are tungsten carbide balls or zirconium oxide balls, and the ball-to-material ratio is 5~15:1; Step 2: Press the mixture obtained in Step 1 into a compact shape; Step 3: Place the pressed billet obtained in Step 2 into a graphite crucible in a plasma arc furnace. First, argon gas is introduced to purge the air, then argon gas and carbon monoxide are introduced, with the partial pressure of argon gas being 0.3 MPa and the partial pressure of carbon monoxide gas being 3 MPa. Set the voltage of the plasma arc furnace to 30V and the current to 250A. Turn on the plasma arc and heat to 650℃, hold for 2 hours, then set the voltage of the plasma arc furnace to 50V and the current to 300A, heat to 1100℃, hold for 1 hour, and cool to room temperature under an atmosphere of argon and carbon monoxide to obtain vanadium carbide.

2. The method for preparing vanadium carbide as described in claim 1, characterized in that, In step one, the carbonaceous powder is at least one of graphite, carbon black, activated carbon, and organic carbon; the molar ratio of V in the vanadium-containing raw material to C in the carbonaceous powder is 1:2~5.

3. The method for preparing vanadium carbide as described in claim 1, characterized in that, In step one, the amount of binder added is 1 to 3% of the total mass of the vanadium-containing raw material and carbonaceous powder.

4. The method for preparing vanadium carbide as described in claim 1, characterized in that, In step two, the pressure parameter for pressing is 10~50MPa.