Medium-grained tungsten carbide powder, its preparation method and use

Abstract

The application belongs to the technical field of metallurgy, and particularly relates to medium-granularity tungsten carbide powder and a preparation method and application thereof. The preparation method comprises the following steps: S1, obtaining nano tungsten oxide, and performing ball milling on the nano tungsten oxide and pure water to obtain tungsten oxide slurry; S2, performing spray drying on the tungsten oxide slurry to obtain tungsten oxide particles; S3, performing first hydrogen reduction, second hydrogen reduction and third hydrogen reduction on the tungsten oxide particles to obtain tungsten powder; and S4, performing sieving and carbon mixing on the tungsten powder to obtain a tungsten-carbon mixture, and performing carbonization, crushing and sieving on the tungsten-carbon mixture to obtain medium-granularity tungsten carbide powder. The application adopts nano tungsten oxide as raw material, and prepares medium-granularity tungsten carbide powder with a Feishigranularity of 5.0-6.0 mu m, a combined carbon content of 6.11-6.12 wt%, and an oxygen content of less than or equal to 0.02 wt% under the condition of 1300-1450 DEG C, which is 400-550 DEG C lower than the traditional carbonization temperature.

Description

Technical Field

[0001] This application relates to the field of metallurgical technology, specifically to a medium-particle tungsten carbide powder, its preparation method, and its application. Background Technology

[0002] Tungsten carbide, known as the "teeth of industry" due to its extremely high hardness and wear resistance, is widely used as a core raw material in the field of cemented carbide (such as CNC cutting tools and tunnel boring machine drill teeth), which can significantly improve tool life. Its applications are expanding from traditional machinery and mining to high-end fields such as aerospace and electronic information.

[0003] Medium-particle tungsten carbide powder is a core raw material for manufacturing cemented carbide, primarily used in the production of tools requiring both good wear resistance and toughness. Typical applications include conventional cutting tools (such as indexable inserts and drill bits), wear-resistant parts (such as molds, rolls, and sandblasting nozzles), and rock drilling teeth and bits used in mining and oil and gas exploration. Currently, the traditional solid-phase carbide method is widely used in industry, which involves mixing tungsten powder with carbon black and carrying out the carbide reaction at a high temperature of 1500-2200℃ under hydrogen protection. In particular, the carbide temperature required to prepare medium-particle tungsten carbide with a Fisher particle size ≥5.0µm is at least 1800℃.

[0004] Traditional methods for preparing medium-particle tungsten carbide powder often suffer from high reaction temperatures and significant graphite product loss. Therefore, it is crucial to develop a medium-particle tungsten carbide powder with high combined carbon and low oxygen content at a lower carbonization temperature. To address the technical challenges of high reaction temperatures and significant graphite product loss in traditional medium-particle tungsten carbide powder preparation processes, and to develop a medium-particle tungsten carbide powder with high combined carbon and low oxygen content at a lower carbonization temperature, a method for preparing medium-particle tungsten carbide powder and its applications are urgently needed. Summary of the Invention

[0005] To solve the above-mentioned technical problems, this application provides a method for preparing medium-particle tungsten carbide powder, comprising the following steps: S1, obtaining nano-tungsten oxide, and ball milling the nano-tungsten oxide with pure water to obtain tungsten oxide slurry, wherein the Fisher particle size of the nano-tungsten oxide is 0.2-0.4µm, and the specific surface area of ​​the nano-tungsten oxide is 8-12m². 2 / g; S2, spray-dry the tungsten oxide slurry to obtain tungsten oxide particles; S3, subject the tungsten oxide particles to first hydrogen reduction, second hydrogen reduction, and third hydrogen reduction to obtain tungsten powder; S4, sieve the tungsten powder, add carbon to obtain a tungsten-carbon mixture, and then carbonize, crush, and sieve the tungsten-carbon mixture to obtain medium-particle tungsten carbide powder.

[0006] In a preferred embodiment of the method for preparing medium-particle tungsten carbide powder as described in this application, in step S1, the solid-liquid ratio of the nano-tungsten oxide and the pure water is (1-2.5):1.

[0007] As a preferred embodiment of the method for preparing medium-particle tungsten carbide powder according to this application, in step S1, the ball-to-material ratio of the ball mill is (2-4):1, and the ball milling time is 1-3 hours.

[0008] As a preferred embodiment of the method for preparing medium-sized tungsten carbide powder according to this application, in step S2, the spray drying is carried out in a spray dryer, the outlet temperature of the spray dryer is 100-110℃, the feed rate of the spray dryer is 70-100Hz, and the spray rotation speed of the spray dryer is 20-40Hz.

[0009] In a preferred embodiment of the method for preparing medium-particle tungsten carbide powder as described in this application, in step S3, the temperature of the first hydrogen reduction is 650-700℃, the temperature of the second hydrogen reduction is 750-800℃, and the temperature of the third hydrogen reduction is 850-900℃; the time for the first hydrogen reduction is 40-60 min, the time for the second hydrogen reduction is 40-60 min, and the time for the third hydrogen reduction is 40-60 min; the hydrogen flow rate for the first hydrogen reduction is 400-600 L / h, the hydrogen flow rate for the second hydrogen reduction is 400-600 L / h, and the hydrogen flow rate for the third hydrogen reduction is 400-600 L / h; the loading amount of the first hydrogen reduction is 80-120 g / boat, the loading amount of the second hydrogen reduction is 80-120 g / boat, and the loading amount of the third hydrogen reduction is 80-120 g / boat.

[0010] In a preferred embodiment of the method for preparing medium-particle tungsten carbide powder as described in this application, in step S4, the total carbon content of the tungsten-carbon mixture is 6.16-6.18 wt%.

[0011] In a preferred embodiment of the method for preparing medium-particle tungsten carbide powder as described in this application, in step S4, the carbonization temperature is 1300-1450℃ and the carbonization time is 100-150min.

[0012] This application also provides a medium-particle tungsten carbide powder, which is prepared using the above-described method for preparing medium-particle tungsten carbide powder.

[0013] As a preferred embodiment of the medium-particle tungsten carbide powder described in this application, the medium-particle tungsten carbide powder has a Fisher particle size of 5.0-6.0µm, a carbon content of 6.11-6.12wt%, and an oxygen content of ≤0.02wt%.

[0014] This application also provides an application of the above-mentioned medium-particle tungsten carbide powder in cemented carbide.

[0015] The beneficial effects of this application are as follows:

[0016] This application provides a medium-particle tungsten carbide powder, its preparation method, and its application. The research in this application found that due to the low loose packing density of nano-tungsten oxide, the amount of material packed in the boat is small, resulting in low yield in the reduction process. After low-intensity ball milling and spray granulation, the gap between each tungsten oxide particle is maintained and the loose packing density of nano-tungsten oxide is significantly improved, thereby improving the reduction efficiency.

[0017] This study also found that a small ball-to-particle ratio, a small solid-liquid ratio, and a short ball milling time result in incomplete dispersion, making it impossible to obtain a uniform slurry. After spray drying, there are many hollow ions or poor ion sphericity, resulting in low bulk density. A high ball-to-material ratio, high solid-liquid ratio, and long ball milling time result in high impurity content, which is detrimental to the subsequent performance improvement of the product. Low outlet temperature and high feed rate in a spray dryer lead to incomplete drying and high moisture content; high outlet temperature and slow feed rate result in low efficiency and high energy consumption. Too slow a spray speed results in low efficiency, while too fast a speed results in small particles and low bulk density. High activity in nano-tungsten oxide, combined with high reduction temperature and long reduction time, easily leads to sintering and growth, forming sintering necks and excessive particle agglomeration. Low reduction temperature and short time result in incomplete reduction and high oxygen content. High hydrogen flow rate and small boat load result in small tungsten powder particles; low hydrogen flow rate and large boat load result in large tungsten powder particles and incomplete reduction. Low carbonization temperature and short carbonization time result in incomplete carbonization and small tungsten carbide particles; high carbonization temperature and long carbonization time result in many solid-phase sintering necks and difficulty in particle dispersion.

[0018] This application uses nano-tungsten oxide as raw material, which, through low-intensity wet milling and spray granulation, maintains the interparticle spacing of tungsten oxide while significantly increasing the loose packing density of nano-tungsten oxide. This effectively solves the problem of low boat loading and low yield during reduction due to the low loose packing density of nano-tungsten oxide. After reduction, the spherical nano-tungsten oxide particles have tight contact between particles, sintering necks, and still maintain high activity. The solid-state sintering effect is significant during carbonization. Medium-sized tungsten carbide powder with a Fisher particle size of 5.0-6.0µm, a combined carbon content of 6.11-6.12wt%, and an oxygen content ≤0.02wt% can be prepared at 1300-1450℃. This is 400-550℃ lower than the traditional carbonization temperature of 1750-1900℃, significantly reducing the carbonization temperature. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is an electron microscope image of the medium-particle tungsten carbide powder prepared in Example 4;

[0021] Figure 2 The image shows the metallographic structure of the cemented carbide prepared in Example 4.

[0022] Figure 3 The image shows an electron microscope image of the medium-particle tungsten carbide powder prepared in Comparative Example 1.

[0023] Figure 4 The image shows the metallographic diagram of the cemented carbide prepared in Comparative Example 1.

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

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

[0026] This application provides a method for preparing medium-sized tungsten carbide powder, comprising the following steps: S1, obtaining nano-tungsten oxide, and ball milling the nano-tungsten oxide with pure water to obtain tungsten oxide slurry, wherein the Fisher particle size of the nano-tungsten oxide is 0.2-0.4µm, and the specific surface area of ​​the nano-tungsten oxide is 8-12m². 2 / g;

[0027] The solid-liquid ratio of the nano-tungsten oxide to the pure water is (1-2.5):1; the ball-to-material ratio of the ball mill is (2-4):1; and the ball milling time is 1-3 hours.

[0028] Specifically, the solid-liquid ratio of the nano-tungsten oxide to the pure water is any one of 1:1, 1.5:1, 2:1, 2.5:1, or any combination thereof; the ball-to-material ratio of the ball mill is any one of 2:1, 2.5:1, 3:1, 3.5:1, 4:1, or any combination thereof; and the ball milling time is any one of 1h, 1.5h, 2h, 2.5h, 3h, or any combination thereof.

[0029] S2. Spray dry the tungsten oxide slurry to obtain tungsten oxide particles;

[0030] The spray drying is carried out in a spray dryer, the outlet temperature of which is 100-110℃, the feed rate of which is 70-100Hz, and the spray rotation speed of which is 20-40Hz.

[0031] S3. The tungsten oxide particles are subjected to a first hydrogen reduction, a second hydrogen reduction, and a third hydrogen reduction to obtain tungsten powder;

[0032] The temperature for the first hydrogen reduction is 650-700℃, the temperature for the second hydrogen reduction is 750-800℃, and the temperature for the third hydrogen reduction is 850-900℃; the time for the first hydrogen reduction is 40-60 min, the time for the second hydrogen reduction is 40-60 min, and the time for the third hydrogen reduction is 40-60 min; the hydrogen flow rate for the first hydrogen reduction is 400-600 L / h, the hydrogen flow rate for the second hydrogen reduction is 400-600 L / h, and the hydrogen flow rate for the third hydrogen reduction is 400-600 L / h; the loading amount of the first hydrogen reduction on the boat is 80-120 g / boat, the loading amount of the second hydrogen reduction on the boat is 80-120 g / boat, and the loading amount of the third hydrogen reduction on the boat is 80-120 g / boat.

[0033] Specifically, the temperature for the first hydrogen reduction is within the range of any one or any two of 650℃, 660℃, 670℃, 680℃, 690℃, and 700℃; the temperature for the second hydrogen reduction is within the range of any one or any two of 750℃, 760℃, 770℃, 780℃, 790℃, and 800℃; and the temperature for the third hydrogen reduction is within the range of any one or any two of 850℃, 860℃, 870℃, 880℃, 890℃, and 900℃.

[0034] S4. The tungsten powder is sieved and carbonized to obtain a tungsten-carbon mixture. The tungsten-carbon mixture is then carbonized, crushed, and sieved to obtain medium-particle tungsten carbide powder.

[0035] The total carbon content of the tungsten-carbon mixture is 6.16-6.18 wt%; the carbonization temperature is 1300-1450℃; and the carbonization time is 100-150 min.

[0036] Specifically, the carbonization temperature is any one or any two of the following: 1300℃, 1310℃, 1320℃, 1330℃, 1340℃, 1350℃, 1360℃, 1370℃, 1380℃, 1390℃, 1400℃, 1410℃, 1420℃, 1430℃, 1440℃, and 1450℃; and the carbonization time is any one or any two of the following: 100min, 110min, 120min, 130min, 140min, and 150min.

[0037] This application also provides a medium-particle tungsten carbide powder, which is prepared by the above-described method for preparing medium-particle tungsten carbide powder; the medium-particle tungsten carbide powder has a Fisher particle size of 5.0-6.0µm, a carbon content of 6.11-6.12wt%, and an oxygen content of ≤0.02wt%.

[0038] This application also provides an application of the above-mentioned medium-particle tungsten carbide powder in cemented carbide.

[0039] The technical solution of this application will be further described below with reference to specific embodiments.

[0040] Example 1

[0041] A medium-particle tungsten carbide powder and its preparation method, comprising:

[0042] S1. Obtain nano-tungsten oxide: Ball mill nano-tungsten oxide and pure water to obtain tungsten oxide slurry, wherein the Fisher particle size of the nano-tungsten oxide is 0.2µm and the specific surface area of ​​the nano-tungsten oxide is 8m². 2 / g;

[0043] The solid-liquid ratio of nano-tungsten oxide to pure water is 1:1; the ball-to-material ratio in the ball mill is 2:1, and the milling time is 3 hours.

[0044] S2. Spray dry the tungsten oxide slurry to obtain tungsten oxide particles;

[0045] Spray drying is carried out in a spray dryer with an outlet temperature of 100℃, a feed rate of 70Hz, and a spray speed of 20Hz.

[0046] S3. Tungsten oxide particles are subjected to a first hydrogen reduction, a second hydrogen reduction, and a third hydrogen reduction to obtain tungsten powder;

[0047] The temperature for the first hydrogen reduction is 650℃, the temperature for the second hydrogen reduction is 750℃, and the temperature for the third hydrogen reduction is 850℃; the time for the first hydrogen reduction is 40 min, the time for the second hydrogen reduction is 40 min, and the time for the third hydrogen reduction is 40 min; the hydrogen flow rate for the first hydrogen reduction is 400 L / h, the hydrogen flow rate for the second hydrogen reduction is 400 L / h, and the hydrogen flow rate for the third hydrogen reduction is 400 L / h; the loading amount of the first hydrogen reduction is 80 g / boat, the loading amount of the second hydrogen reduction is 80 g / boat, and the loading amount of the third hydrogen reduction is 80 g / boat.

[0048] S4. After sieving and adding carbon to the tungsten powder, a tungsten-carbon mixture is obtained. The tungsten-carbon mixture is then carbonized, crushed, and sieved to obtain medium-particle tungsten carbide powder.

[0049] The total carbon content of the tungsten-carbon mixture was 6.18 wt%; the carbonization temperature was 1300℃ and the carbonization time was 100 min.

[0050] The medium-particle tungsten carbide powder prepared in Example 1 was tested, and the results showed that the Fisher particle size of the medium-particle tungsten carbide powder was 5.0 µm, the content of compound carbon in the medium-particle tungsten carbide powder was 6.11 wt%, and the oxygen content in the medium-particle tungsten carbide powder was 0.02 wt%.

[0051] Example 2

[0052] A medium-particle tungsten carbide powder and its preparation method, comprising:

[0053] S1. Obtain nano-tungsten oxide: Ball mill nano-tungsten oxide and pure water to obtain tungsten oxide slurry, wherein the Fisher particle size of the nano-tungsten oxide is 0.3µm and the specific surface area of ​​the nano-tungsten oxide is 10m². 2 / g;

[0054] The solid-liquid ratio of nano-tungsten oxide to pure water was 2.5:1; the ball-to-material ratio in the ball mill was 4:1, and the milling time was 1 hour.

[0055] S2. Spray dry the tungsten oxide slurry to obtain tungsten oxide particles;

[0056] Spray drying is carried out in a spray dryer with an outlet temperature of 110℃, a feed rate of 100Hz, and a spray speed of 40Hz.

[0057] S3. Tungsten oxide particles are subjected to a first hydrogen reduction, a second hydrogen reduction, and a third hydrogen reduction to obtain tungsten powder;

[0058] The temperature for the first hydrogen reduction is 700℃, the temperature for the second hydrogen reduction is 800℃, and the temperature for the third hydrogen reduction is 900℃; the time for the first hydrogen reduction is 60 min, the time for the second hydrogen reduction is 60 min, and the time for the third hydrogen reduction is 60 min; the hydrogen flow rate for the first hydrogen reduction is 600 L / h, the hydrogen flow rate for the second hydrogen reduction is 600 L / h, and the hydrogen flow rate for the third hydrogen reduction is 600 L / h; the loading amount of the first, second, and third hydrogen reductions is 120 g / boat.

[0059] S4. After sieving and adding carbon to the tungsten powder, a tungsten-carbon mixture is obtained. The tungsten-carbon mixture is then carbonized, crushed, and sieved to obtain medium-particle tungsten carbide powder.

[0060] The total carbon content of the tungsten-carbon mixture was 6.16 wt%; the carbonization temperature was 1450℃ and the carbonization time was 150 min.

[0061] The medium-particle tungsten carbide powder prepared in Example 2 was tested, and the results showed that the Fisher particle size of the medium-particle tungsten carbide powder was 5.5 µm, the content of compound carbon in the medium-particle tungsten carbide powder was 6.12 wt%, and the oxygen content in the medium-particle tungsten carbide powder was 0.01 wt%.

[0062] Example 3

[0063] A medium-particle tungsten carbide powder and its preparation method, comprising:

[0064] S1. Obtain nano-tungsten oxide: Ball mill nano-tungsten oxide and pure water to obtain tungsten oxide slurry, wherein the Fisher particle size of the nano-tungsten oxide is 0.4µm and the specific surface area of ​​the nano-tungsten oxide is 12m². 2 / g;

[0065] The solid-liquid ratio of nano-tungsten oxide to pure water was 1.5:1; the ball-to-material ratio in the ball mill was 3:1, and the milling time was 2 hours.

[0066] S2. Spray dry the tungsten oxide slurry to obtain tungsten oxide particles;

[0067] Spray drying is carried out in a spray dryer with an outlet temperature of 105℃, a feed rate of 85Hz, and a spray speed of 30Hz.

[0068] S3. Tungsten oxide particles are subjected to a first hydrogen reduction, a second hydrogen reduction, and a third hydrogen reduction to obtain tungsten powder;

[0069] The temperature for the first hydrogen reduction is 680℃, the temperature for the second hydrogen reduction is 780℃, and the temperature for the third hydrogen reduction is 880℃; the time for the first hydrogen reduction is 50 min, the time for the second hydrogen reduction is 50 min, and the time for the third hydrogen reduction is 50 min; the hydrogen flow rate for the first hydrogen reduction is 500 L / h, the hydrogen flow rate for the second hydrogen reduction is 500 L / h, and the hydrogen flow rate for the third hydrogen reduction is 500 L / h; the amount of hydrogen in the boat for the first hydrogen reduction is 100 g / boat, the amount of hydrogen in the boat for the second hydrogen reduction is 100 g / boat, and the amount of hydrogen in the boat for the third hydrogen reduction is 100 g / boat.

[0070] S4. After sieving and adding carbon to the tungsten powder, a tungsten-carbon mixture is obtained. The tungsten-carbon mixture is then carbonized, crushed, and sieved to obtain medium-particle tungsten carbide powder.

[0071] The total carbon content of the tungsten-carbon mixture was 6.17 wt%; the carbonization temperature was 1380℃ and the carbonization time was 130 min.

[0072] The medium-sized tungsten carbide powder prepared in Example 3 was tested, and the results showed that the Fisher particle size of the medium-sized tungsten carbide powder was 6.0 µm, the content of compound carbon in the medium-sized tungsten carbide powder was 6.11 wt%, and the oxygen content in the medium-sized tungsten carbide powder was 0.01 wt%.

[0073] Example 4

[0074] A medium-particle tungsten carbide powder, its preparation method, and its applications include:

[0075] S1. Obtain nano-tungsten oxide: Ball mill nano-tungsten oxide and pure water to obtain tungsten oxide slurry, wherein the Fisher particle size of the nano-tungsten oxide is 0.2µm and the specific surface area of ​​the nano-tungsten oxide is 10m². 2 / g;

[0076] The solid-liquid ratio of nano-tungsten oxide to pure water is 1:1; the ball-to-material ratio in the ball mill is 2:1, and the milling time is 2 hours.

[0077] S2. Spray dry the tungsten oxide slurry to obtain tungsten oxide particles;

[0078] Spray drying is carried out in a spray dryer with an outlet temperature of 100℃, a feed rate of 70Hz, and a spray speed of 40Hz.

[0079] S3. Tungsten oxide particles are subjected to a first hydrogen reduction, a second hydrogen reduction, and a third hydrogen reduction to obtain tungsten powder;

[0080] The temperature for the first hydrogen reduction is 680℃, the temperature for the second hydrogen reduction is 780℃, and the temperature for the third hydrogen reduction is 880℃; the time for the first hydrogen reduction is 50 min, the time for the second hydrogen reduction is 50 min, and the time for the third hydrogen reduction is 50 min; the hydrogen flow rate for the first hydrogen reduction is 500 L / h, the hydrogen flow rate for the second hydrogen reduction is 500 L / h, and the hydrogen flow rate for the third hydrogen reduction is 500 L / h; the loading amount of the first hydrogen reduction is 110 g / boat, the loading amount of the second hydrogen reduction is 110 g / boat, and the loading amount of the third hydrogen reduction is 110 g / boat.

[0081] S4. After sieving and adding carbon to the tungsten powder, a tungsten-carbon mixture is obtained. The tungsten-carbon mixture is then carbonized, crushed, and sieved to obtain medium-particle tungsten carbide powder.

[0082] The total carbon content of the tungsten-carbon mixture was 6.17 wt%; the carbonization temperature was 1450℃ and the carbonization time was 150 min.

[0083] Please see Figure 1 , Figure 1 The image shows an electron microscope image of the medium-particle tungsten carbide powder prepared in Example 4. The medium-particle tungsten carbide powder prepared in Example 4 was tested, and the results showed that the Fisher particle size of the medium-particle tungsten carbide powder was 5.7 µm, the content of compound carbon in the medium-particle tungsten carbide powder was 6.12 wt%, and the oxygen content in the medium-particle tungsten carbide powder was 0.01 wt%.

[0084] Using the medium-particle tungsten carbide powder prepared in Example 4 as raw material, cobalt powder, paraffin wax, alcohol, and grain inhibitor were added in proportion for wet milling, spray drying, and pressing. The mixture was then sintered at 1430°C for 1 hour in a hydrogen atmosphere. For testing of the prepared cemented carbide, please refer to [link to relevant documentation]. Figure 2 , Figure 2 The image shows the metallographic structure of the cemented carbide prepared in Example 4. The cemented carbide exhibits a bicrystalline structure, a hardness HV10 of 1510, and a fracture toughness of 13.1 MPa·m. 1 / 2 .

[0085] Comparative Example 1

[0086] The difference between this comparative example and Example 4 is that micron-sized tungsten oxide is used instead of nano-sized tungsten oxide in step S1, while the other steps are the same as in Example 4.

[0087] For the analysis of the medium-particle tungsten carbide powder prepared in Comparative Example 1, please refer to [link / reference needed]. Figure 3 , Figure 3 The image shows an electron microscope image of the medium-sized tungsten carbide powder prepared in Comparative Example 1. The results show that there are abnormally large particles. The Fisher particle size of the medium-sized tungsten carbide powder is 5.8 µm, the content of compound carbon in the medium-sized tungsten carbide powder is 6.07 wt%, and the oxygen content in the medium-sized tungsten carbide powder is 0.03 wt%.

[0088] Using the medium-particle tungsten carbide powder prepared in Comparative Example 1 as raw material, cobalt powder, paraffin wax, alcohol, and grain inhibitor were added in proportion for wet milling, spray drying, and pressing. The mixture was then sintered at 1430℃ for 1 hour in a hydrogen atmosphere. For the testing of the prepared cemented carbide, please refer to [link to relevant documentation]. Figure 4 , Figure 4 The image shows the metallographic diagram of the cemented carbide prepared in Comparative Example 1. The cemented carbide contains abnormally large particles, has a hardness HV10 of 1501, and a fracture toughness of 11.48 MPa·m. 1 / 2 .

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 4 is that steps S1 and S2 are omitted, and the nano-tungsten oxide is directly subjected to the first hydrogen reduction, the second hydrogen reduction, and the third hydrogen reduction. All other steps are the same as in Example 4.

[0091] The medium-sized tungsten carbide powder prepared in Comparative Example 2 was tested. The results showed that the Fisher particle size of the medium-sized tungsten carbide powder was 1.54 µm, the content of compound carbon in the medium-sized tungsten carbide powder was 6.06 wt%, and the oxygen content in the medium-sized tungsten carbide powder was 0.07 wt%.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 4 is that the carbonization temperature in step S4 is 1250°C, while the other steps are the same as in Example 4.

[0094] The medium-sized tungsten carbide powder prepared in Comparative Example 3 was tested. The results showed that the Fisher particle size of the medium-sized tungsten carbide powder was 3.5 µm, the content of compound carbon in the medium-sized tungsten carbide powder was 6.08 wt%, and the oxygen content in the medium-sized tungsten carbide powder was 0.03 wt%.

[0095] Comparative Example 4

[0096] The difference between this comparative example and Example 4 is that the carbonization temperature in step S4 is 1500°C, while the other steps are the same as in Example 4.

[0097] The medium-particle tungsten carbide powder prepared in Comparative Example 4 was tested. The results showed that the Fisher particle size of the medium-particle tungsten carbide powder was 6.0 µm, the content of compound carbon in the medium-particle tungsten carbide powder was 6.08 wt%, and the oxygen content in the medium-particle tungsten carbide powder was 0.04 wt%.

[0098] Comparative Example 5

[0099] The difference between this comparative example and Example 4 is that in step S3, segmented hydrogen reduction is not performed, but a single-stage hydrogen reduction is used. The hydrogen reduction temperature is 780°C and the time is 150 min. All other steps are the same as in Example 4.

[0100] The medium-particle tungsten carbide powder prepared in Comparative Example 5 was tested. The results showed that the Fisher particle size of the medium-particle tungsten carbide powder was 3.1 µm, the content of compound carbon in the medium-particle tungsten carbide powder was 6.11 wt%, and the oxygen content in the medium-particle tungsten carbide powder was 0.05 wt%.

[0101] As can be seen from the above examples and comparative examples: Example 4, combined with Comparative Example 1, shows that under the light ball milling process, micron-sized tungsten oxide cannot effectively break down and disperse dense tungsten oxide particles, resulting in coarse particles. This leads to incomplete carbonization of tungsten carbide, low combined carbon, abnormally large particles, and high oxygen content. The resulting cemented carbide also exhibits abnormally large particles and reduced fracture toughness. However, using nano-tungsten oxide can effectively avoid these problems. Example 4, combined with Comparative Example 2, shows that after reduction, the ungranulated nano-tungsten oxide powder is fine, has high surface activity, is prone to agglomeration, and lacks sintering necks between particles. The relatively poor solid-phase sintering during subsequent carbonization results in small tungsten carbide particles and high oxygen content. Furthermore, the easy agglomeration of ultrafine tungsten powder makes it difficult to mix evenly with carbon black, leading to low combined carbon in tungsten carbide. Example 4, in conjunction with Comparative Example 3, demonstrates that a suitable carbonization temperature is required to ensure that the prepared tungsten carbide particle size reaches the target value, and that carbonization is complete with high combined carbon content. If the temperature is too low, the solid-state sintering effect is relatively weak, and the particles cannot effectively sinter and grow, resulting in small particle size, incomplete carbonization, and low combined carbon content. Example 4, in conjunction with Comparative Example 4, demonstrates that if the carbonization temperature is too high, excessive sintering and growth between particles can easily occur, resulting in abnormally large particles, incomplete carbonization, and low combined carbon content. Example 4, in conjunction with Comparative Example 5, demonstrates that the tungsten powder prepared by one-step reduction is coarser, has lower activity, and higher oxygen content; the prepared tungsten carbide particles are small and have higher oxygen content. Examples 1-4, together with Comparative Examples 1-5, show that using nano-tungsten oxide as raw material, wet milling through light ball milling and spray granulation can effectively improve the bulk density of nano-tungsten oxide, increase production efficiency, and control the reduction and carbonization temperature. This allows for the preparation of medium-sized tungsten carbide with the same particle size, high degree of carbonization, and low oxygen content at a significantly lower carbonization temperature compared to traditional medium-particle tungsten carbide.

[0102] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for preparing medium-particle tungsten carbide powder, characterized in that, Includes the following steps: S1. Obtain nano-tungsten oxide by ball milling the nano-tungsten oxide with pure water to obtain a tungsten oxide slurry, wherein the Fisher particle size of the nano-tungsten oxide is 0.2-0.4µm and the specific surface area of ​​the nano-tungsten oxide is 8-12m². 2 / g; S2. Spray dry the tungsten oxide slurry to obtain tungsten oxide particles; S3. The tungsten oxide particles are subjected to a first hydrogen reduction, a second hydrogen reduction, and a third hydrogen reduction to obtain tungsten powder; S4. The tungsten powder is sieved and carbonized to obtain a tungsten-carbon mixture. The tungsten-carbon mixture is then carbonized, crushed, and sieved to obtain medium-particle tungsten carbide powder. In step S1, the solid-liquid ratio of the nano-tungsten oxide to the pure water is (1-2.5):1; the ball-to-material ratio of the ball milling is (2-4):1; and the ball milling time is 1-3 hours. In step S2, the spray drying is carried out in a spray dryer with an outlet temperature of 100-110℃, a feed rate of 70-100Hz, and a spray rotation speed of 20-40Hz. In step S3, the temperature of the first hydrogen reduction is 650-700℃, the temperature of the second hydrogen reduction is 750-800℃, and the temperature of the third hydrogen reduction is 850-900℃; the time for the first hydrogen reduction is 40-60 min, the time for the second hydrogen reduction is 40-60 min, and the time for the third hydrogen reduction is 40-60 min; the hydrogen flow rate for the first hydrogen reduction is 400-600 L / h, the hydrogen flow rate for the second hydrogen reduction is 400-600 L / h, and the hydrogen flow rate for the third hydrogen reduction is 400-600 L / h; the loading amount of the first hydrogen reduction boat is 80-120 g / boat, the loading amount of the second hydrogen reduction boat is 80-120 g / boat, and the loading amount of the third hydrogen reduction boat is 80-120 g / boat. In step S4, the carbonization temperature is 1300-1450℃ and the carbonization time is 100-150min; The medium-particle tungsten carbide powder has a Fisher particle size of 5.0-6.0µm, a carbon content of 6.11-6.12wt%, and an oxygen content of ≤0.02wt%.

2. The method for preparing medium-particle tungsten carbide powder according to claim 1, characterized in that, In step S4, the total carbon content of the tungsten-carbon mixture is 6.16-6.18 wt%.

3. A medium-particle tungsten carbide powder, characterized in that, It is prepared by the method for preparing medium-particle tungsten carbide powder according to any one of claims 1-2.

4. The application of the medium-particle tungsten carbide powder as described in claim 3 in cemented carbide.

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