Ultrafine grain hard alloy mixture as well as preparation method and application thereof

Abstract

The invention discloses an ultra-fine grain hard alloy mixture and a preparation method and application thereof, and belongs to the technical field of hard alloy manufacturing. The ultra-fine grain hard alloy mixture is prepared from the following raw materials in parts by weight: 87 to 93.1 parts of WC, 6 to 12 parts of Co, 0.55 to 0.85 part of Cr3C2 and 0.25 to 0.35 part of VC, the preparation method specifically comprises the following steps: (1) weighing the raw materials; and (2) adding a forming agent, grinding, drying, sieving, carrying out compression molding, and sintering. According to the prepared ultra-fine grain WC-Co hard alloy, the components are evenly mixed, particle contact and reaction are more sufficient in the sintering process, abnormal growth of WC grains in the alloy can be effectively avoided, meanwhile, the phenomenon of coarse clamping is avoided, and the performance of the alloy is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide manufacturing technology, and more specifically to an ultrafine-grained cemented carbide mixture, its preparation method, and its application. Background Technology

[0002] Ultrafine-grained tungsten carbide-cobalt (WC-Co) cemented carbide, due to its ultra-high hardness, strength, and wear resistance, is used to manufacture micro-drills for processing integrated circuit boards, medical dental drills, precision molds, and cutting tools for difficult-to-machine materials, making it one of the best candidate materials for high-speed, precision machining. Ultrafine-grained WC-Co cemented carbide typically uses ultrafine WC powder as raw material. Due to the small size effect of ultrafine powder, WC powder is not easily and uniformly mixed with Co powder during ball milling. Furthermore, the high surface activity and strong sintering driving force of ultrafine powder lead to easy growth and coarsening of WC grains during sintering. To suppress grain growth, grain growth inhibitors are usually added during mixture preparation. However, these grain growth inhibitors also face the problem of mixing uniformity during ball milling. Therefore, obtaining a mixed powder with appropriate particle size, uniform composition, and excellent forming and sintering properties is a technical challenge in the preparation of ultrafine-grained WC-Co cemented carbide.

[0003] Currently, the industrial preparation of cemented carbide mixtures mainly employs wet grinding, which uses alcohol or hexane as the grinding medium. Powdered components such as WC, Co, and grain inhibitors are fed into a grinding mill, where they are ground and mixed using grinding media. The grinding media can be spherical (typically 4–10 mm in diameter), or cylindrical or polyhedral shapes of similar size. Cylindrical or other shaped grinding media have low grinding efficiency and produce large-particle-size mixtures, generally used for preparing coarse-grained or ultra-coarse-grained cemented carbides requiring low grinding efficiency. Spherical grinding media offer high grinding efficiency and uniform mixing, and are widely used for preparing ultrafine-grained WC-Co cemented carbide mixtures. However, the traditional wet grinding process for preparing ultrafine-grained WC-Co mixtures requires a long grinding time to achieve uniform mixing, leading to high grinding kinetic energy, severe powder processing strain, poor formability, and high sintering activity. This causes abnormal growth of WC grains during sintering, resulting in severe alloy inclusions and reduced alloy performance.

[0004] Patent CN102202817B discloses a ball milling process for a cemented carbide mixture, characterized by employing a stirred ball milling process to improve grinding efficiency. In this process, the diameter of the cemented carbide balls is 4–6 mm, the rotation speed of the stirring arm is 100–135 rpm, and the ball milling time is 6–8 hours. Although stirred ball milling can improve grinding efficiency, due to the limitations of the movement of the grinding balls and the internal structure of the grinding cylinder, some areas of the mixture may not be sufficiently ground, resulting in uneven grinding of the mixture.

[0005] Patent CN103537702B discloses a method for preparing high-flexural-strength nano-WC-Co alloy powder. This method involves batching the powder under vacuum conditions and wet milling it under argon protection to prevent oxidation and improve the uniformity and dispersibility of the powder composition. Simultaneously, nano-rare earth oxides are added to inhibit grain growth in the WC-Co cemented carbide. While this method can prevent powder oxidation, it fails to address the high sintering activity of the mixture caused by milling, leading to abnormal grain growth during sintering; furthermore, the uniformity of the added nano-rare earth oxides is difficult to guarantee.

[0006] Patent CN117684036A discloses an ultrafine-grained cemented carbide and its preparation method. The optimized ball milling process results in a cemented carbide with uniform WC grain distribution, reducing coarse grain aggregation and inclusions. The ball milling is performed in stages. The first stage lasts 1–5 hours, involving pre-mixing 15–25% WC powder (by weight) with Cr3C2 powder, VC powder, 1 / 5 volume of alcohol, and a surfactant. The second stage involves ball milling the powder from the first stage with Co powder and the remaining WC powder, adding the remaining alcohol and a forming agent. This second stage lasts 23–40 hours. Patent CN113201677A discloses a production process for ultrafine-grained cemented carbide using subfine tungsten carbide. This process employs multiple ball milling, multiple stops, a high ball-to-material ratio, and special-temperature sintering to process WC powder (subfine tungsten carbide) with a particle size of 0.4–0.6 μm into ultrafine-grained cemented carbide. The total wet milling time is 48–150 hours, with a 4–5 hour rest period after each ball milling before the next ball milling, and the number of ball milling cycles is 3–5. Although the above two methods use segmented wet milling to ensure the uniformity of the mixture, they use cemented carbide balls for grinding, and the grinding time and grinding kinetic energy are long, which makes it easy for the grains to grow abnormally during the sintering process.

[0007] Patent CN102994792A discloses a method for preparing high-strength, high-hardness nanocrystalline tungsten-cobalt cemented carbide. It uses sub-fine WC powder as raw material and prepares the mixture through a combination of intensified grinding and wet milling. The intensified grinding uses the chemical reagent Tween 80 to improve grinding efficiency, and the grinding media is a mixture of acetone and n-hexane. Cemented carbide balls are used for grinding for 24–48 hours at a ball-to-powder ratio of 3.25:1; wet milling is performed using cemented carbide balls for 24 hours at a ball-to-powder ratio of 5:1. While this method can save costs, the high grinding kinetic energy and long duration of the intensified crushing of sub-fine WC powder with cemented carbide balls for 24–48 hours and the 24-hour wet milling of the mixed powder result in high sintering activity in the mixture, leading to WC grain growth and inclusions during sintering. Furthermore, the uniformity of the mixture is mainly achieved through 24 hours of wet milling with cemented carbide balls, but the mixing efficiency of cemented carbide balls is relatively poor, and 24 hours of wet milling is insufficient to guarantee uniformity.

[0008] Patent CN109457163B discloses a rare-earth element-free ultrafine-grained cemented carbide material and its preparation method. This method involves spray drying the ball-milled powder to obtain a granulated mixture with a stable carbon / oxygen ratio, low impurity content, uniform spherical particle size, good flowability, and stable flow rate. However, this method fails to address the problem of high kinetic energy during grinding and high sintering activity in the mixture.

[0009] Patent CN103890204A discloses a non-contact mixer that uses resonant acoustic waves to mix powders, maintaining the particle size, particle size distribution, and morphology of WC particles for the preparation of high-strength and high-toughness cemented carbides. While this method achieves good mixing results, it does not break up the original agglomerated WC powder, leading to the formation of coarse grains during sintering.

[0010] Patent CN118621174A discloses a high-performance ultrafine cemented carbide and its preparation method. This method first prepares ultrafine WC powder containing inhibitors through liquid-liquid doping, then prepares a rhenium-boron ternary boride binder through reduction and mixing, and finally mixes the ultrafine WC powder and the cobalt-rhenium-boron ternary boride and ball-mills the mixture to obtain a composite material. The ball-to-powder ratio for preparing the composite material is 10:1, and the ball-milling time is 12 hours. Although this method can solve the problem of inhibitor dispersion uniformity, using cemented carbide balls for 12 hours makes it difficult to guarantee the uniformity of the mixture between the ultrafine WC powder and the cobalt-rhenium-boron ternary boride binder.

[0011] The aforementioned patents provide new ideas and methods for preparing ultrafine-grained cemented carbide mixtures, but in practical applications, factors such as cost, operational complexity, safety, and final product performance need to be considered, making them unsuitable for industrial production. Furthermore, the methods described above struggle to address the issues of uniform dispersion of ultrafine WC, Co, and inhibitors during the preparation of ultrafine cemented carbides, as well as the abnormal growth of WC grains during sintering.

[0012] Therefore, how to develop a new process for preparing ultrafine-grained WC-Co cemented carbide mixtures to obtain mixture powders with appropriate particle size, uniform composition, and excellent forming and sintering properties is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0013] In view of this, the purpose of the present invention is to provide an ultrafine-grained cemented carbide mixture, its preparation method and application, so as to overcome the shortcomings of the prior art.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] An ultrafine-grained cemented carbide mixture comprises the following raw materials in parts by weight: 87-93.1 parts WC, 6-12 parts Co, 0.55-0.85 parts Cr3C2 and 0.25-0.35 parts VC.

[0016] Furthermore, the aforementioned ultrafine-grained cemented carbide mixture comprises the following raw materials in parts by weight: 93.1 parts WC, 6 parts Co, 0.55 parts Cr3C2, and 0.35 parts VC.

[0017] Furthermore, the aforementioned ultrafine-grained cemented carbide mixture comprises the following raw materials in parts by weight: 90.9 parts WC, 8 parts Co, 0.75 parts Cr3C2, and 0.35 parts VC.

[0018] Furthermore, the aforementioned ultrafine-grained cemented carbide mixture comprises the following raw materials in parts by weight: 89.9 parts WC, 9 parts Co, 0.85 parts Cr3C2, and 0.25 parts VC.

[0019] Furthermore, the aforementioned ultrafine-grained cemented carbide mixture comprises the following raw materials in parts by weight: 87 parts WC, 12 parts Co, 275 parts Cr3C, and 0.25 parts VC.

[0020] Furthermore, the powder particle size FSSS of WC is 0.4 μm; the powder particle size FSSS of Co is 1.0 μm.

[0021] A method for preparing an ultrafine-grained cemented carbide mixture specifically includes the following steps:

[0022] (1) Weigh each raw material according to the above-mentioned parts by weight of ultrafine-grained cemented carbide mixture;

[0023] (2) Add a molding agent, grind, dry and sieve, press and shape, and sinter to obtain an ultrafine crystal hard alloy mixture.

[0024] Furthermore, in step (2) above, the molding agent is paraffin wax, with a content of 2.0wt% to 3.0wt%, preferably 2.5wt%.

[0025] Furthermore, in step (2) above, the grinding process uses a diameter of D (3-6 mm) × L (10-20 mm) and a density of 6.5 g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods and D 6-10mm cemented carbide balls are used together as grinding media; the weight ratio of cermet rods to cemented carbide balls is (1-2):1; the weight ratio of grinding media to raw material powder is (4-8):1.

[0026] Furthermore, in step (2) above, the grinding process uses a diameter of 3mm*L20mm and a density of 6.5g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods and D 6mm cemented carbide balls are used together as grinding media; the weight ratio of cermet rods to cemented carbide balls is 1:1; the weight ratio of grinding media to raw material powder is 6:1.

[0027] The further beneficial effects of the above-mentioned method are that the present invention uses a combination of cermet rods and cemented carbide balls as grinding media, which not only helps to reduce the impact kinetic energy during grinding and obtain highly dispersed ultrafine powder, thus achieving efficient mixing of materials, but also reduces the processing strain and lattice distortion of the powder, reduces subgrain defects, maintains the complete morphology of WC grains, and improves the quality of the mixture, thereby obtaining high-performance ultrafine-grained WC-Co cemented carbide.

[0028] Furthermore, in step (2) above, the grinding medium is hexane with a content of 300-450 mL / kg, preferably 400 mL / kg.

[0029] Furthermore, in step (2) above, the grinding speed is 70-80 r / min, preferably 72 r / min; the grinding time is 20-40 h, preferably 30 h.

[0030] Furthermore, in step (2) above, the sintering equipment is a low-pressure sintering furnace with a temperature of 1425℃ and a pressure of 5MPa.

[0031] The present invention also claims the use of the above-described ultrafine-grained cemented carbide mixture or the ultrafine-grained cemented carbide mixture prepared by the above-described preparation method in the preparation of micro drills for integrated circuit boards, medical dental drills, precision molds, and cutting tools for difficult-to-machine materials.

[0032] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The present invention uses a grinding media composed of a metal ceramic rod and a cemented carbide ball, which is conducive to achieving uniform mixing of materials, effectively reducing processing strain and lattice distortion during the grinding process, and maintaining the integrity and morphology of WC grains, further improving the crushing efficiency of materials and obtaining more highly dispersed ultrafine powder.

[0034] 2. The present invention uses a grinding media composed of a metal ceramic rod and a cemented carbide ball, which significantly shortens the grinding time of the material and helps to reduce production costs.

[0035] 3. The present invention uses a grinding media composed of a metal ceramic rod and a cemented carbide ball, which reduces the strain during powder processing and improves the formability of the mixture.

[0036] 4. The ultrafine-grained WC-Co cemented carbide prepared by this invention has a uniformly mixed composition, and the particles have more contact and reaction during the sintering process. This can effectively prevent abnormal growth of WC grains in the alloy, solve the problem of inclusion, and effectively improve the performance of the alloy.

[0037] 5. The production process of this invention is simple, efficient, and highly operable, making it suitable for industrial mass production. Attached Figure Description

[0038] Figure 1 The image shown is a metallographic photograph of the ultrafine-grained WC-6.0%Co cemented carbide from Example 1, magnified 1500 times. The microstructure is uniform and has few coarse grains.

[0039] Figure 2 The metallographic photograph of the ultrafine-grained WC-6.0%Co cemented carbide in Comparative Example 1-1, magnified 1500 times, shows the presence of a small amount of coarse grains.

[0040] Figure 3 The metallographic images of the ultrafine-grained WC-6.0%Co cemented carbide in Comparative Examples 1-2, magnified 1500 times, show a large number of coarse grains. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] The ultrafine-grained cemented carbide mixture comprises the following raw materials by weight: WC 93.1g, Co 6g, Cr3C2 0.55g and VC 0.35g;

[0044] Among them, the powder particle size FSSS of WC is 0.4 μm, and the powder particle size FSSS of Co is 1.0 μm;

[0045] The preparation method of the above-mentioned ultrafine-grained cemented carbide mixture specifically includes the following steps:

[0046] (1) Weigh each raw material according to the weight of the above-mentioned ultrafine crystal hard alloy mixture to obtain raw material powder;

[0047] (2) Add 1.5 kg of raw material powder into a 3 L ball mill, then add 37.5 g of paraffin and 600 mL of hexane for grinding, using a diameter of 3 mm * L of 20 mm and a density of 6.5 g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods and D 6mm cemented carbide balls were used together as grinding media. The weight ratio of the cermet rods to the cemented carbide balls was 1:1, and the weight ratio of the grinding media to the raw material powder was 6:1. The rotation speed was 72 r / min. After grinding for 30 hours, the mixture was dried and sieved to obtain the mixture.

[0048] (3) Press the mixture into a cemented carbide billet with a diameter of 4mm and an in diameter of 50mm;

[0049] (4) A low-pressure sintering furnace is used to sinter at 1425℃ and 5MPa to obtain WC-6.0%Co ultrafine-grained cemented carbide mixture.

[0050] Example 2

[0051] The ultrafine-grained cemented carbide mixture comprises the following raw materials by weight: WC 90.9g, Co 8g, Cr3C2 0.75g and VC 0.35g;

[0052] Among them, the powder particle size FSSS of WC is 0.4 μm, and the powder particle size FSSS of Co is 1.0 μm;

[0053] The preparation method of the above-mentioned ultrafine-grained cemented carbide mixture specifically includes the following steps:

[0054] (1) Weigh each raw material according to the weight of the above-mentioned ultrafine crystal hard alloy mixture to obtain raw material powder;

[0055] (2) Add 1.5 kg of raw material powder into a 3 L ball mill, then add 37.5 g of paraffin and 600 mL of hexane for grinding, using a diameter of 3 mm * L of 20 mm and a density of 6.5 g / cm³. 3Lightweight Ti(C,N)-WC-Ni cermet rods and D 6mm cemented carbide balls were used together as grinding media. The weight ratio of the cermet rods to the cemented carbide balls was 1:1, and the weight ratio of the grinding media to the raw material powder was 6:1. The rotation speed was 72 r / min. After grinding for 30 hours, the mixture was dried and sieved to obtain the mixture.

[0056] (3) Press the mixture into a cemented carbide billet with a diameter of 4mm and an in diameter of 50mm;

[0057] (4) A low-pressure sintering furnace is used to sinter at 1425℃ and 5MPa to obtain WC-8%Co ultrafine-grained cemented carbide mixture.

[0058] Example 3

[0059] The ultrafine-grained cemented carbide mixture comprises the following raw materials by weight: WC 89.9g, Co 9g, Cr3C2 0.85g and VC 0.25g;

[0060] Among them, the powder particle size FSSS of WC is 0.4 μm, and the powder particle size FSSS of Co is 1.0 μm;

[0061] The preparation method of the above-mentioned ultrafine-grained cemented carbide mixture specifically includes the following steps:

[0062] (1) Weigh each raw material according to the weight of the above-mentioned ultrafine crystal hard alloy mixture to obtain raw material powder;

[0063] (2) Add 1.5 kg of raw material powder into a 3 L ball mill, then add 37.5 g of paraffin and 600 mL of hexane for grinding, using a diameter of 3 mm * L of 20 mm and a density of 6.5 g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods and D 6mm cemented carbide balls were used together as grinding media. The weight ratio of the cermet rods to the cemented carbide balls was 1:1, and the weight ratio of the grinding media to the raw material powder was 6:1. The rotation speed was 72 r / min. After grinding for 30 hours, the mixture was dried and sieved to obtain the mixture.

[0064] (3) Press the mixture into a cemented carbide billet with a diameter of 4mm and an in diameter of 50mm;

[0065] (4) A low-pressure sintering furnace is used to sinter at 1425℃ and 5MPa to obtain WC-9%Co ultrafine-grained cemented carbide mixture.

[0066] Example 4

[0067] The ultrafine-grained cemented carbide mixture comprises the following raw materials by weight: WC 87g, Co 12g, Cr3C2 75g and VC 0.25g;

[0068] Among them, the powder particle size FSSS of WC is 0.4 μm, and the powder particle size FSSS of Co is 1.0 μm;

[0069] The preparation method of the above-mentioned ultrafine-grained cemented carbide mixture specifically includes the following steps:

[0070] (1) Weigh each raw material according to the weight of the above-mentioned ultrafine crystal hard alloy mixture to obtain raw material powder;

[0071] (2) Add 1.5 kg of raw material powder into a 3 L ball mill, then add 37.5 g of paraffin and 600 mL of hexane for grinding, using a diameter of 3 mm * L of 20 mm and a density of 6.5 g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods and D 6mm cemented carbide balls were used together as grinding media. The weight ratio of the cermet rods to the cemented carbide balls was 1:1, and the weight ratio of the grinding media to the raw material powder was 6:1. The rotation speed was 72 r / min. After grinding for 30 hours, the mixture was dried and sieved to obtain the mixture.

[0072] (3) Press the mixture into a cemented carbide billet with a diameter of 4mm and an in diameter of 50mm;

[0073] (4) A low-pressure sintering furnace is used to sinter at 1425℃ and 5MPa to obtain WC-12%Co ultrafine-grained cemented carbide mixture.

[0074] Comparative Example 1-1

[0075] The only difference from Example 1 is that it uses D 3mm*L 20mm, density 6.5g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods were used as grinding media for grinding.

[0076] Comparative Examples 1-2

[0077] The only difference from Example 1 is that a D 6mm cemented carbide ball is used as the grinding medium for grinding.

[0078] Comparative Example 2-1

[0079] The only difference from Example 2 is that it uses D 3mm*L 20mm, density 6.5g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods were used as grinding media for grinding.

[0080] Comparative Example 2-2

[0081] The only difference from Example 2 is that a D 6mm cemented carbide ball is used as the grinding medium for grinding.

[0082] Comparative Example 3-1

[0083] The only difference from Example 3 is that it uses D 3mm*L 20mm and density 6.5g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods were used as grinding media for grinding.

[0084] Comparative Example 3-2

[0085] The only difference from Example 3 is that a D 6mm cemented carbide ball is used as the grinding medium for grinding.

[0086] Comparative Example 4-1

[0087] The only difference from Example 4 is that it uses D 3mm*L 20mm, density 6.5g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods were used as grinding media for grinding.

[0088] Comparative Example 4-2

[0089] The only difference from Example 4 is that a D 6mm cemented carbide ball is used as the grinding medium for grinding.

[0090] Performance testing

[0091] The ultrafine-grained cemented carbide mixtures prepared in the examples and comparative examples were tested for their magnetic force, hardness, and inclusion properties, and their microstructure was observed. The results are shown in Table 1 and... Figure 1-3 As shown.

[0092] Table 1. Performance of the ultrafine-grained cemented carbide mixtures in the examples and comparative examples.

[0093] Sample alloy Magnetic force (kA / m) Hardness (HV30) Thick Example 1 44.0±0.2 2100±10 1-0-0-0 Comparative Example 1-1 43.1±1.0 2080±30 1-2-0-0 Comparative Examples 1-2 42.0±0.9 2050±30 3-1-1-0 Example 2 36.0±0.4 1950±10 1-0-0-0 Comparative Example 2-1 34.5±1.0 1930±30 2-1-0-0 Comparative Example 2-2 33.0±1.2 1910±30 3-1-0-1 Example 3 34.2±0.4 1930±10 1-0-0-0 Comparative Example 3-1 32.4±0.9 1910±30 4-1-0-0 Comparative Example 3-2 32.0±1.3 1900±30 3-1-3-1 Example 4 28.0±0.3 1770±10 1-0-0-0 Comparative Example 4-1 27.5±1.0 1750±30 3-1-0-1 Comparative Example 4-2 26.8±1.0 1730±30 4-1-2-1

[0094] Note: Evaluation method for coarse grains: Mark 4-1-2-1 indicates that: for metallographic specimens, when observed at 1500x magnification in 10 fields of view, the total number of coarse grains of 1.5-3.0μm in the worst field of view is 4; when observed at 1500x magnification in 5 fields of view, the total number of coarse grains of 3.0-6.0μm in the worst field of view is 1; when observed at 200x magnification on the entire polished surface of the specimen, the total number of coarse grains of 6.0-10.0μm is 2, and the total number of coarse grains ≥10μm is 1.

[0095] As shown in Table 1, the alloy samples from Examples 1-4 exhibit higher magnetic strength and hardness, as well as better control over inclusions. The alloy samples from Comparative Examples 1-1, 2-1, 3-1, and 4-1 show slightly lower magnetic strength and hardness than their corresponding Examples 1-4, and their magnetic strength and hardness fluctuate significantly. This indicates that only alloys with a diameter of 3mm*L20mm and a density of 6.5g / cm³ were used. 3The grinding efficiency of using lightweight Ti(C,N)-WC-Ni cermet rods as grinding media is low, resulting in large particle sizes in the prepared mixture powder and unstable alloy properties. The magnetic properties and hardness of the alloys in Comparative Examples 1-2, 2-2, 3-2, and 4-2 are significantly lower than those in their corresponding Examples 1-4, and they exhibit obvious coarse grain phenomena and poor control of inclusions. The presence of obvious inclusions in the alloys indicates that using only 6mm D cemented carbide balls as grinding media failed to achieve the ideal dispersion state of the mixture, significantly reducing the alloy's performance.

[0096] Depend on Figure 1-3 It can be seen that the alloy of Example 1 has a uniform microstructure and few coarse grains. The alloy of Comparative Example 1-1 has a small amount of coarse grains. The alloy of Comparative Example 1-2 has a large amount of coarse grains.

[0097] Through comparison of experimental data, it was found that the preparation process of the ultrafine-grained WC-Co cemented carbide mixture provided by the present invention can effectively avoid abnormal growth of WC grains in the alloy, solve the problem of inclusion, and effectively improve the performance of the alloy; at the same time, the production process is simple, efficient, and highly operable, and is suitable for industrial mass production.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fine-grained cemented carbide mixture, characterized in that, The raw materials include the following parts by weight: WC 87-93.1 parts, Co 6-12 parts, Cr3C2 0.55-0.85 parts and VC 0.25-0.35 parts.

2. The ultrafine-grained cemented carbide mixture according to claim 1, characterized in that, The raw materials include the following parts by weight: 93.1 parts WC, 6 parts Co, 0.55 parts Cr3C2 and 0.35 parts VC.

3. The ultrafine-grained cemented carbide mixture according to claim 1, characterized in that, The raw materials include the following parts by weight: 90.9 parts WC, 8 parts Co, 0.75 parts Cr3C2 and 0.35 parts VC.

4. The ultrafine-grained cemented carbide mixture according to claim 1, characterized in that, The raw materials include the following parts by weight: 89.9 parts WC, 9 parts Co, 0.85 parts Cr3C2 and 0.25 parts VC.

5. The ultrafine-grained cemented carbide mixture according to claim 1, characterized in that, The raw materials include the following parts by weight: 87 parts WC, 12 parts Co, 275 parts Cr3C and 0.25 parts VC.

6. The ultrafine-grained cemented carbide mixture according to any one of claims 1 to 5, characterized in that, The powder particle size FSSS of WC is 0.4 μm; the powder particle size FSSS of Co is 1.0 μm.

7. A method for preparing an ultrafine-grained cemented carbide mixture, characterized in that, Specifically, the following steps are included: (1) Weigh each raw material according to the weight proportions of the ultrafine-grained cemented carbide mixture according to any one of claims 1 to 6; (2) Add a molding agent, grind, dry and sieve, press and shape, and sinter to obtain the ultrafine crystal hard alloy mixture.

8. The method for preparing an ultrafine-grained cemented carbide mixture according to claim 7, characterized in that, In step (2), the molding agent is paraffin wax, with a content of 2.0 wt% to 3.0 wt%.

9. The method for preparing an ultrafine-grained cemented carbide mixture according to claim 7, characterized in that, In step (2), the grinding process uses a diameter of D (3-6 mm) × L (10-20 mm) and a density of 6.5 g / cm³. 3 Lightweight Ti(C,N)-WC-Ni cermet rods and D 6-10mm cemented carbide balls are used together as grinding media; the weight ratio of the cermet rods to the cemented carbide balls is (1-2):1; the weight ratio of the grinding media to the raw material powder is (4-8):

1. The grinding medium is hexane, with a content of 300-450 mL / kg; The grinding speed is 70-80 r / min, and the time is 20-40 h; The sintering equipment is a low-pressure sintering furnace with a temperature of 1425℃ and a pressure of 5MPa.

10. The application of an ultrafine-grained cemented carbide mixture as described in any one of claims 1 to 6 or an ultrafine-grained cemented carbide mixture prepared by any one of claims 7 to 9 in the preparation of micro drills, medical dental drills, precision molds, and cutting tools for machining integrated circuit boards.

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