Low-nitrogen high-purity tungsten carbide powder and preparation method thereof

Abstract

The invention discloses low-nitrogen high-purity tungsten carbide powder and a preparation method thereof. The Fsss granularity of the tungsten carbide powder is 0.8-30 microns, the WC content is larger than or equal to 99.99 wt%, and the N element content is smaller than or equal to 0.001 wt%. The preparation method comprises the following steps: mixing tungsten powder and carbon black, carbonizing, and crushing. By controlling the purity of the raw materials, avoiding nitrogen permeation in the preparation process and optimizing process conditions, high purity and low nitrogen content of the tungsten carbide powder are achieved, and the problem that the nitrogen content in the tungsten carbide copper alloy is too high can be solved.

Description

Technical Field

[0001] This invention belongs to the technical field of tungsten carbide powder materials, specifically relating to a low-nitrogen, high-purity tungsten carbide powder and its preparation method. Background Technology

[0002] Tungsten carbide copper powder metallurgy composite material is a pseudo-alloy composed of high-melting-point, high-hardness tungsten carbide and high-conductivity, high-thermal-conductivity copper. Due to its good resistance to arc erosion, resistance to welding, and high strength and hardness, it is widely used as electrical contact material, resistance welding, electrical discharge machining and plasma electrode material, electrothermal alloy and high-density alloy, special-purpose military material (such as rocket nozzles, aircraft throat liners, etc.), and heat sink substrate for electronic devices such as computer central processing systems, lead frames of large-scale integrated circuits and solid-state microwave tubes.

[0003] Low-nitrogen tungsten carbide copper alloy is a tungsten carbide copper composite material produced by strictly controlling the nitrogen content (typically much lower than that of ordinary tungsten carbide copper alloys). Its core characteristic is to reduce the adverse effects of nitride precipitation on material properties while retaining the high melting point and high hardness of tungsten carbide and the excellent electrical and thermal conductivity of copper. Typically, the nitrogen content needs to be controlled at an extremely low level, generally <0.0050 wt%, to avoid the formation of tungsten nitrides (such as WN, W₂N), thereby reducing brittle phases and microscopic defects within the material.

[0004] The national standard GB / T4295-2019, Tungsten Carbide Powder, requires that the main component (i.e., purity) of tungsten carbide be no less than 99.80%, but there is no explicit requirement for nitrogen content. The nitrogen content in commercially available conventional tungsten carbide powder is usually between 0.0120% and 0.0300%, which cannot meet the raw material quality requirements for low-nitrogen tungsten carbide copper alloys.

[0005] Chinese patent CN112317757A discloses a method for processing tungsten powder with a purity of 99.995~99.999% using a plasma torch to obtain ultra-high purity tungsten powder with a purity ≥99.9995%; Chinese patent CN120421520A discloses a submicron-level high-purity tungsten powder and its preparation method, which involves mixing ammonium paratungstate and ammonia to obtain a mixture, subjecting the mixture to ammonia dissolution treatment, filtering to obtain an ammonium tungstate solution, and then performing ion exchange using a strongly acidic cation exchange resin, resulting in a solution after exchange. A high-purity ammonium tungstate solution is obtained by chelating resin exchange, followed by vacuum spraying, freeze drying, and hydrogen reduction reaction to obtain submicron-sized high-purity tungsten powder. This effectively removes insoluble particles and metal cation impurities from the solution, resulting in a high-purity tungsten precursor solution. Chinese patent CN116081625A discloses a tungsten carbide powder and its preparation method and application. By preparing tungsten powder with uniform particle size distribution, a multi-stage temperature-controlled carbonization method is used for carbonization. After processing, tungsten carbide powder of different particle sizes can be obtained in one step.

[0006] While the aforementioned solutions involve the purification of tungsten powder and the preparation of tungsten carbide, none provide a method for controlling low nitrogen content. Chinese patent CN114951676A discloses a method for preparing high-purity WO3 using high-purity APT as raw material, followed by gas-crush pretreatment and a segmented calcination process, and then preparing high-purity tungsten powder through high-temperature hydrogen reduction. The nitrogen content in the tungsten powder can reach as low as 10 ppm. However, this patent only addresses the control of low nitrogen content in tungsten powder. Compared to tungsten powder, the preparation process of tungsten carbide powder also includes a carbonization step, increasing the pathway for nitrogen penetration. Therefore, this method is not suitable for controlling low nitrogen content in tungsten carbide powder. Summary of the Invention

[0007] The purpose of this invention is to provide a low-nitrogen, high-purity tungsten carbide powder and its preparation method, so as to solve at least one aspect of the problems and defects mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A low-nitrogen, high-purity tungsten carbide powder, wherein the tungsten carbide powder has an Fsss particle size of 0.8~30μm, wherein the WC content is ≥99.99wt% and the N element content is ≤0.001wt%.

[0009] As a further embodiment of the present invention, the tungsten carbide powder contains ≥99.991wt% tungsten carbide.

[0010] As a further embodiment of the present invention, the nitrogen content in the tungsten carbide powder is ≤0.0009wt%.

[0011] As a further embodiment of the present invention, the C element content in the tungsten carbide powder is 5.5~6.2wt%, preferably 5.9~6.16wt%.

[0012] As a further embodiment of the present invention, the sulfur content in the tungsten carbide powder is ≤0.0005wt%, preferably ≤0.0002wt%.

[0013] As a further embodiment of the present invention, the K content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0014] As a further embodiment of the present invention, the Na content in the tungsten carbide powder is ≤0.0005wt%, preferably ≤0.0001wt%.

[0015] As a further embodiment of the present invention, the P element content in the tungsten carbide powder is ≤0.0005wt%, preferably ≤0.0003wt%.

[0016] As a further embodiment of the present invention, the Fe content in the tungsten carbide powder is ≤0.01wt%, preferably ≤0.0015wt%.

[0017] As a further embodiment of the present invention, the Al content in the tungsten carbide powder is ≤0.0005wt%, preferably ≤0.0001wt%.

[0018] As a further embodiment of the present invention, the Si content in the tungsten carbide powder is ≤0.0005wt%, preferably ≤0.0004wt%.

[0019] As a further embodiment of the present invention, the Mn content in the tungsten carbide powder is ≤0.001wt%, preferably ≤0.0005wt%.

[0020] As a further embodiment of the present invention, the Mg content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0021] As a further embodiment of the present invention, the Ni content in the tungsten carbide powder is ≤0.001wt%, preferably ≤0.0008wt%.

[0022] As a further embodiment of the present invention, the Pb content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0023] As a further embodiment of the present invention, the Bi element content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0024] As a further embodiment of the present invention, the Sn element content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0025] As a further embodiment of the present invention, the Sb content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0026] As a further embodiment of the present invention, the Co content in the tungsten carbide powder is ≤0.003wt%, preferably ≤0.001wt%.

[0027] As a further embodiment of the present invention, the As content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.001wt%.

[0028] As a further embodiment of the present invention, the Ca content in the tungsten carbide powder is ≤0.001wt%, preferably ≤0.0006wt%.

[0029] As a further embodiment of the present invention, the Mo content in the tungsten carbide powder is ≤0.0005wt%, preferably ≤0.0005wt%.

[0030] As a further embodiment of the present invention, the Cr content in the tungsten carbide powder is ≤0.001wt%, preferably ≤0.0008wt%.

[0031] As a further embodiment of the present invention, the V element content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0032] As a further embodiment of the present invention, the Cu content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0033] As a further embodiment of the present invention, the Cd content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0034] As a further embodiment of the present invention, the Ti element content in the tungsten carbide powder is ≤0.0003wt%, preferably ≤0.0001wt%.

[0035] The preparation method of low-nitrogen high-purity tungsten carbide powder as described in any of the above methods includes mixing tungsten powder with carbon black, carbonizing the mixture, and then crushing it to obtain the low-nitrogen high-purity tungsten carbide powder.

[0036] As a further embodiment of the present invention, an inert gas is used for protection during the preparation process.

[0037] As a further embodiment of the present invention, the inert gas includes at least one of helium and argon, preferably argon.

[0038] As a further embodiment of the present invention, the Fsss particle size of the tungsten powder is 0.8~30μm.

[0039] As a further embodiment of the present invention, the carbon black has a purity of ≥99.95%, preferably ≥99.98%.

[0040] As a further embodiment of the present invention, the tungsten powder is obtained by reducing tungsten oxide.

[0041] As a further embodiment of the present invention, the purity of the tungsten oxide is ≥99.97%, preferably ≥99.99%.

[0042] As a further aspect of the present invention, a compression molding process is also included.

[0043] As a further embodiment of the present invention, the container wall is cooled by circulating cooling water during the crushing process.

[0044] As a further embodiment of the present invention, the preparation method includes the following steps: S1. Tungsten oxide is reduced with hydrogen to obtain tungsten powder; S2. Mix the tungsten powder with carbon black, so that the carbon black fully coats the surface of the tungsten powder particles to obtain a mixture; S3. The mixture is pressed into shape and then carbonized to obtain block tungsten carbide; S4. The blocky tungsten carbide is ball-milled to obtain the low-nitrogen, high-purity tungsten carbide powder.

[0045] As a further embodiment of the present invention, steps S1 to S4 are all performed under argon protection.

[0046] As a further embodiment of the present invention, the reduction temperature in step S1 is 650~1000℃.

[0047] As a further embodiment of the present invention, the reduction time in step S1 is 4~7 hours.

[0048] As a further embodiment of the present invention, the loading amount in step S1 is 0.8~4.0Kg / boat.

[0049] As a further embodiment of the present invention, the hydrogen flow rate in step S1 is 10~50m³. 3 / h.

[0050] As a further embodiment of the present invention, the mesh size of the sieve in step S1 is 140~325 mesh.

[0051] As a further embodiment of the present invention, the purity of hydrogen in step S1 is ≥99.99%.

[0052] As a further embodiment of the present invention, the Fsss particle size of the tungsten powder in step S1 is 0.8~30μm.

[0053] As a further embodiment of the present invention, step S1 uses a fully automatic fifteen-tube reduction furnace for reduction.

[0054] As a further embodiment of the present invention, argon gas is introduced in step S1 for closed purification to prevent contact with air.

[0055] As a further embodiment of the present invention, the purity of tungsten oxide in step S1 is ≥99.99%.

[0056] As a further embodiment of the present invention, step S1 uses a five-zone temperature-controlled furnace for heating and reduction.

[0057] As a further embodiment of the present invention, the carbon black in step S2 is metallurgical grade high-purity carbon black.

[0058] As a further embodiment of the present invention, the amount of carbon black added in step S2 is determined according to the total carbon content requirement in the tungsten carbide powder. For example, if the total carbon content is required to be 6.13%, then 61.3 kg of carbon black is added to one ton of tungsten powder.

[0059] As a further embodiment of the present invention, the argon flow rate in step S2 is 3~8m³ / h. 3 / h.

[0060] As a further embodiment of the present invention, the mixing time in step S2 is 3-5 hours.

[0061] As a further embodiment of the present invention, in step S2, cooling water is passed through the mixer wall for cooling and passivation.

[0062] As a further embodiment of the present invention, the cooling time in step S2 is 5-6 hours.

[0063] As a further embodiment of the present invention, in step S3, pressing the mixture of tungsten powder and carbon black into shape can expel the gas adsorbed between the powder particles, effectively preventing the formation of tungsten nitride. Pressing can be performed using conventional molds, and the pressed shape can be a cube or cylinder, etc.

[0064] As a further embodiment of the present invention, step S3 uses a boat-shaped vessel to place the pressed mixture in the boat-shaped vessel for carbonization.

[0065] As a further embodiment of the present invention, the vessel is made of high-purity graphite.

[0066] As a further embodiment of the present invention, the carbonization temperature in step S3 is 1400~2000℃.

[0067] As a further embodiment of the present invention, the carbonization time in step S3 is 2 to 6 hours.

[0068] As a further embodiment of the present invention, the cooling time in step S3 is 5-6 hours.

[0069] As a further embodiment of the present invention, carbonization is carried out in a fully automatic carbonization furnace in step S3.

[0070] As a further embodiment of the present invention, the mass ratio of balls in step S4 is 1:(1~2).

[0071] As a further embodiment of the present invention, the crushing time in step S4 is 1 to 4 hours.

[0072] As a further embodiment of the present invention, the cooling time in step S4 is 5-6 hours.

[0073] As a further embodiment of the present invention, the mesh size of the sieve in step S4 is 140~325 mesh.

[0074] As a further embodiment of the present invention, a ball mill is used in step S4, the ball mill being lined with a tungsten-cobalt hard alloy.

[0075] As a further embodiment of the present invention, the cobalt content in the tungsten-cobalt cemented carbide is 3~8wt%.

[0076] As a further embodiment of the present invention, the tungsten-cobalt cemented carbide is a YG grade alloy, which has high hardness and high wear resistance, and is preferably a tungsten-cobalt YG8 grade alloy.

[0077] As a further embodiment of the present invention, argon gas is used for protection during the ball milling and crushing process in step S4.

[0078] As a further embodiment of the present invention, the ball mill wall is cooled and passivated by circulating cooling water.

[0079] This invention uses high-purity tungsten oxide as raw material and obtains tungsten carbide powder through an industrial production process of tungsten oxide-hydrogen reduction-tungsten powder-carbon mixing-loading-carbonization-unloading-ball milling. By innovating process parameters and optimizing equipment, the nitrogen content in tungsten carbide powder is significantly reduced, thereby improving the overall performance of tungsten carbide powder.

[0080] The present invention has at least the following technical effects: Using high-purity oxides and high-purity carbon black as raw materials, the purity of tungsten carbide powder is guaranteed from the source. Inert argon gas is used as the protective purification gas during the preparation process, and the entire process is sealed to prevent nitrogen infiltration from contact with air during production. A pressing and molding carbonization method is used when mixing tungsten and carbon black. This method removes adsorbed gases from the material and reduces the contact area between the material and the graphite boat, ensuring material purity. Simultaneously, the conditions and parameters of each step are optimized to achieve high purity and low nitrogen content of tungsten carbide powder under overall process control. The prepared tungsten carbide powder has a purity of over 99.99% and a nitrogen content of less than 0.0010 wt%, solving the problem of high nitrogen content in tungsten carbide copper alloys. This allows the material to retain the high melting point and high hardness of tungsten carbide and the excellent electrical and thermal conductivity of copper, while avoiding the formation of tungsten nitrides (such as WN and W₂N), reducing brittle phases and microscopic defects within the material, and meeting the performance requirements of low-nitrogen tungsten carbide copper alloy products. Attached Figure Description

[0081] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0082] Figure 1 This is a flowchart illustrating the preparation process of low-nitrogen, high-purity tungsten carbide powder in an embodiment of the present invention. Detailed Implementation

[0083] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments.

[0084] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0085] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0086] In the following embodiments: The purity of high-purity tungsten oxide is 99.99%; The carbon black is metallurgical grade high-purity carbon black with a purity of 99.98%. The purity of high-purity hydrogen is 99.99%.

[0087] The overall preparation process of low-nitrogen, high-purity tungsten carbide powder of this invention is as follows: Figure 1 As shown, tungsten oxide raw material is reduced with hydrogen and sieved to obtain tungsten powder; then it is mixed with carbon, carbonized, ball-milled, sieved, and inspected to obtain finished tungsten carbide powder.

[0088] Example 1 A method for preparing low-nitrogen, high-purity tungsten carbide powder includes the following steps: (1) High-purity tungsten oxide raw material is fed into a fully automatic fifteen-tube reduction furnace and high-purity hydrogen is introduced for reduction. The hydrogen flow rate is 42 m³ / s. 3 The furnace operates at a rate of 1.2 kg / boat, using a five-zone temperature-controlled furnace for heating and reduction. The temperatures of each zone are set sequentially to 650℃, 750℃, 850℃, 900℃, and 950℃. The reduction time is 5 hours. After the reduction is complete, the tungsten powder is removed from the furnace, poured into the charging hopper under argon protection, and passed through a 200-mesh sieve to obtain tungsten powder with a particle size of 1.5 μm. (2) The obtained tungsten powder and carbon black were mixed for 5 hours. After mixing, the mixer wall was cooled and passivated by cooling water for 6 hours. Argon gas was introduced throughout the mixing and cooling process at a flow rate of 5 m³ / h. 3 / h; (3) The uniformly mixed tungsten powder and carbon black mixture is placed in a sealed argon-filled press to press into shape. The pressing pressure is 130KN and the holding time is 2min. After loading the boat, it is pushed into a fully automatic carbonization furnace for carbonization. The carbonization temperature is set to 1500℃ and the carbonization time is 2h. After carbonization, the boat is pushed into the cooling zone of the carbonization furnace. Cooling water is circulated in the furnace tube of the cooling zone for 5h to obtain block tungsten carbide. (4) The obtained blocky tungsten carbide is subjected to ball milling, crushing and sieving. The ball mill is lined with a high-hardness and high-wear-resistant tungsten-cobalt YG8 alloy. The ball mill body is made of tungsten-cobalt YG8 alloy and has three sizes: Ф6, 10 and 15 mm. It is filled with 5 m³ of argon gas. 3 The ball mill is protected at a ratio of 1:1 to 1, and the crushing time is 4 hours. After the crushing is completed, the ball mill wall is cooled and passivated by cooling water for 6 hours. The powder is then passed through a 180-mesh sieve to obtain tungsten carbide powder.

[0089] Example 2 A method for preparing low-nitrogen, high-purity tungsten carbide powder includes the following steps: (1) High-purity tungsten oxide raw material is fed into a fully automatic fifteen-tube reduction furnace and high-purity hydrogen is introduced for reduction. The hydrogen flow rate is 30 m³ / h. 3 The furnace operates at a rate of 2.5 kg / boat, using a five-zone temperature-controlled furnace for heating and reduction. The temperatures of each zone are set sequentially to 750℃, 850℃, 900℃, 950℃, and 980℃. The reduction time is 6 hours. After the reduction is complete, the tungsten powder is removed from the furnace, poured into the charging hopper under argon protection, and passed through a 260-mesh sieve to obtain tungsten powder with a particle size of 3.5 μm. (2) The obtained tungsten powder and carbon black were mixed for 4 hours. After mixing, the mixer wall was cooled and passivated by passing cooling water for 5 hours. Argon gas was introduced throughout the mixing and cooling process at a flow rate of 5 m³ / h. 3 / h; (3) The mixture of tungsten powder and carbon black is placed in a sealed argon-filled press and pressed into shape. The pressing pressure is 130KN and the holding time is 2min. After loading the boat, it is pushed into a fully automatic carbonization furnace for carbonization. The carbonization temperature is set to 1700℃ and the carbonization time is 4h. After carbonization, the boat is pushed into the cooling zone of the carbonization furnace. Cooling water is circulated in the furnace tube of the cooling zone and the cooling time is 6h to obtain block tungsten carbide. (4) The obtained blocky tungsten carbide is subjected to ball milling, crushing and sieving. The ball mill is lined with a high-hardness and high-wear-resistant tungsten-cobalt YG8 alloy. The ball mill body is made of tungsten-cobalt YG8 alloy and has three sizes: Ф6, 10 and 15 mm. It is filled with 5 m³ of argon gas. 3 The ball mill is protected at a ratio of 1:1.5, and the crushing time is 3 hours. After the crushing is completed, the ball mill wall is cooled and passivated by cooling water for 5 hours. The powder is then passed through a 260-mesh sieve to obtain tungsten carbide powder.

[0090] Example 3 A method for preparing low-nitrogen, high-purity tungsten carbide powder includes the following steps: (1) High-purity tungsten oxide raw material is fed into a fully automatic fifteen-tube reduction furnace and high-purity hydrogen is introduced for reduction. The hydrogen flow rate is 12 m³ / s. 3 The furnace was heated and reduced at a rate of 4 kg / boat per hour using a five-zone temperature-controlled furnace. The temperatures of each zone were set to 900℃, 950℃, 980℃, 1000℃ and 1000℃ respectively. The reduction time was 8 hours. After the reduction was completed, the tungsten powder was discharged from the furnace, poured into the charging hopper under argon protection, and passed through a 140-mesh sieve to obtain tungsten powder with a particle size of 20.2 μm. (2) The obtained tungsten powder and carbon black were mixed for 3 hours. After mixing, the mixer wall was cooled and passivated by cooling water for 5 hours. Argon gas was introduced throughout the mixing and cooling process at a flow rate of 5 m³ / h. 3 / h; (3) The uniformly mixed tungsten powder and carbon black mixture is placed in a sealed argon-filled press to press into shape. The pressing pressure is 130KN and the holding time is 2min. After loading the boat, it is pushed into a fully automatic carbonization furnace for carbonization. The carbonization temperature is set to 2000℃ and the carbonization time is 6h. After carbonization, the boat is pushed into the cooling zone of the carbonization furnace. Cooling water is circulated in the furnace tube of the cooling zone for 6h to obtain block tungsten carbide. (4) The obtained blocky tungsten carbide is subjected to ball milling, crushing and sieving. The ball mill is lined with a high-hardness and high-wear-resistant tungsten-cobalt YG8 alloy. The ball mill body is made of tungsten-cobalt YG8 alloy and has three sizes: Ф6, 10 and 15 mm. It is filled with 5 m³ of argon gas. 3 The ball mill is protected at a ratio of 1:2, and the crushing time is 1 hour. After the crushing is completed, the ball mill wall is cooled and passivated by cooling water for 5 hours. The powder is then passed through a 140-mesh sieve to obtain tungsten carbide powder.

[0091] Comparative Example 1 A method for preparing low-nitrogen, high-purity tungsten carbide powder includes the following steps: (1) High-purity tungsten oxide raw material is fed into a fully automatic fifteen-tube reduction furnace and high-purity hydrogen is introduced for reduction. The hydrogen flow rate is 38 m³ / h. 3 / h, with a boat loading of 1.8Kg / boat, a five-band temperature-controlled furnace was used for heating and reduction, with the temperatures of each band set to 750℃, 850℃, 880℃, 930℃ and 980℃ respectively, and the reduction time was 5h. The tungsten powder was sieved through a 200-mesh screen and the particle size of the obtained tungsten powder was 2.1μm. (2) The obtained tungsten powder and carbon black are mixed for 5 hours. After the mixing is completed, the mixer wall is cooled and passivated by cooling water for 2 hours. (3) Place the uniformly mixed tungsten powder and carbon black mixture in a graphite boat, and push the boat into the fully automatic carbonization furnace for carbonization. The carbonization temperature is set to 1700℃ and the carbonization time is 2h. After carbonization, push the boat into the cooling zone of the carbonization furnace. Cooling water is circulated in the furnace tubes of the cooling zone for 5h. (4) The obtained tungsten carbide is subjected to ball milling and sieving. The ball mill is lined with a high-hardness and high-wear-resistant tungsten-cobalt YG8 alloy. The ball mill body is made of tungsten-cobalt YG8 alloy and has three sizes: Ф6, 10, and 15 mm. The inner wall of the ball mill is not circulated with cooling water. The ball-to-material mass ratio is 1:1. The crushing time is 4 hours. The ball is sieved through 180 mesh to obtain tungsten carbide powder.

[0092] The average particle size and composition analysis of the tungsten carbide powder obtained in Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0093] Table 1

[0094] Note: The content of WC principal component is obtained by subtracting the sum of the measured values ​​of the impurity component contents listed in the table from 100%.

[0095] The results showed that the tungsten carbide powder prepared by the methods in Examples 1-3 all had a tungsten carbide content exceeding 99.99 wt% and a nitrogen content below 0.001 wt%, while the tungsten carbide powder obtained in Comparative Example 1 had a nitrogen content of 0.0120 wt% and a tungsten carbide content below 99.99 wt%. This indicates that the preparation method of the present invention can significantly reduce the content of impurities such as nitrogen in tungsten carbide powder and improve the purity of the finished tungsten carbide powder.

[0096] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 60-90, in this specification it means specifically listing values ​​such as 61-89, 62-88, ..., 61-71, and 80-81. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0097] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A low nitrogen high purity tungsten carbide powder, characterized by, The Fsss particle size of the tungsten carbide powder is 0.8-30 μm, the WC content is ≥99.99 wt%, and the N element content is ≤0.001 wt%.

2. The tungsten carbide powder of claim 1, wherein, At least one of the following characteristics is satisfied: (1) the C element content is 5.5-6.2 wt%; (2) the S element content is ≤0.0005 wt%; (3) the K element content is ≤0.0003 wt%; (4) the Na element content is ≤0.0005 wt%; (5) the P element content is ≤0.0005 wt%; (6) the Fe element content is ≤0.01 wt%; (7) the Al element content is ≤0.0005 wt%; (8) the Si element content is ≤0.0005 wt%; (9) the Mn element content is ≤0.001 wt%; (10) the Mg element content is ≤0.0003 wt%; (11) the Ni element content is ≤0.001 wt%; (12) the Pb element content is ≤0.0003 wt%; (13) the Bi element content is ≤0.0003 wt%; (14) the Sn element content is ≤0.0003 wt%; (15) the Sb element content is ≤0.0003 wt%; (16) the Co element content is ≤0.003 wt%; (17) the As element content is ≤0.0003 wt%; (18) the Ca element content is ≤0.001 wt%; (19) the Mo element content is ≤0.0005 wt%; (20) the Cr element content is ≤0.001 wt%; (21) the V element content is ≤0.0003 wt%; (22) the Cu element content is ≤0.0003 wt%; (23) the Cd element content is ≤0.0003 wt%; (24) the Ti element content is ≤0.0003 wt%.

3. The method of claim 1 or 2, wherein the low-nitrogen high-purity tungsten carbide powder is prepared by the steps of: The low-nitrogen high-purity tungsten carbide powder is obtained by mixing tungsten powder with carbon black, carbonizing, and then crushing. ​ 4. The production method according to claim 3, characterized by, Inert gas is used for protection during the preparation process.

5. The preparation method according to claim 4, characterized in that, The inert gas is argon.

6. The preparation method according to claim 3, characterized in that, The purity of the carbon black is ≥99.95%.

7. The preparation method according to claim 3, characterized in that, The tungsten powder is obtained by reduction of tungsten oxide.

8. The preparation method according to claim 7, characterized in that, The purity of the tungsten oxide is ≥99.97%.

9. The preparation method according to claim 3, characterized in that, The process also includes a pressing forming process.

10. The method of claim 3, wherein, The container wall is cooled by cooling water during the crushing process.

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