A high-toughness cemented carbide and its preparation method

Abstract

This invention discloses a high-toughness cemented carbide and its preparation method, belonging to the technical field of cemented carbide materials. The method includes: firstly, ball milling and mixing tantalum carbide powder with a liquid medium to prepare a tantalum carbide dispersion slurry; then, wet milling tungsten carbide powder (5-30% by weight of tungsten carbide powder) and cobalt powder in a liquid medium to prepare a tungsten carbide-cobalt mixed slurry; mixing the tungsten carbide-cobalt mixed slurry with the tantalum carbide dispersion slurry to obtain a mixed slurry; then adding the remaining tungsten carbide powder and a forming agent to the mixed slurry and continuing ball milling; after ball milling, drying, granulation, molding, and sintering to obtain the high-toughness cemented carbide. This invention can effectively disperse tantalum carbide, thereby reducing the agglomeration of tantalum carbide in the cemented carbide, preventing tantalum carbide agglomeration sites from becoming fracture sources, significantly enhancing the fracture toughness while maintaining the high hardness of the cemented carbide, and the process is simple, easy to implement, and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide materials technology, and in particular to a high-toughness cemented carbide and its preparation method. Background Technology

[0002] Hard alloys are composite materials prepared using powder metallurgy with refractory metal carbides as the matrix and iron group elements as the binder phase. They possess characteristics such as high hardness, high red hardness, and high strength. In hard alloys with tungsten carbide (WC) as the matrix, the grain size of WC often affects a series of performance indicators such as hardness, toughness, and bending strength. To enhance the hardness of hard alloys, adding carbides such as tantalum carbide (TaC) or TiC to refine the grains is a very common method. Currently, the most suitable way to add TaC for industrial production is to directly add TaC solid particles. The typical particle size range of the added TaC particles is <1μm, with common specifications being 0.5-0.8μm. The problem with this method is that TaC particles are difficult to disperse uniformly in the mixture. Undispersed micron-sized TaC hard clusters become local stress concentration points, which crack before other parts under load or thermal shock, becoming crack initiation points and significantly reducing the fracture toughness of the alloy.

[0003] To address the aforementioned issue of uneven TaC dispersion, existing technologies have attempted to employ a wet ball milling process to mix TaC with other powders, aiming to achieve initial dispersion using a liquid medium and the ball milling action. However, this process often requires extended ball milling time or increased ball milling intensity to achieve TaC dispersion, inevitably leading to excessive fragmentation and refinement of the WC matrix. While excessive refinement of WC grains can improve alloy hardness, it severely impairs fracture toughness; furthermore, during prolonged mixing, TaC particles tend to undergo reverse milling or re-agglomeration, which conventional ball milling cannot completely deagglomerate and stably disperse. In addition, existing technologies have also employed (W,Ta)C binary solid solutions to replace pure TaC powder. For example, Chinese patent CN103667843A discloses improving TaC dispersibility by pre-forming a solid solution. However, this approach alters the form and mechanism of action of TaC, requires specialized solid solution raw materials, resulting in higher costs and a relatively complex preparation process.

[0004] Therefore, how to improve the dispersion uniformity of TaC in cemented carbide without sacrificing the appropriate coarsening of WC grains to obtain high toughness, without changing the TaC addition morphology, without increasing raw material costs, and only by improving the process route, remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention aims to solve the technical problems of uneven dispersion and easy agglomeration of tantalum carbide in cemented carbide in existing technologies, and provides a high-toughness cemented carbide and its preparation method. The method employs a staged preparation process. First, tantalum carbide is dispersed separately to prepare a slurry. Then, a portion of tungsten carbide and cobalt powder are used to pre-prepare a tungsten carbide-cobalt slurry. Subsequently, the slurries are mixed, and the remaining tungsten carbide and a forming agent are added later, ultimately yielding a high-toughness cemented carbide. Through this process, tantalum carbide achieves uniform dispersion in the cemented carbide matrix, significantly improving the fracture toughness of the alloy while maintaining high hardness.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a method for preparing a high-toughness cemented carbide, comprising the following steps: Step 1: After ball milling and mixing tantalum carbide powder with liquid medium, dispersion treatment is carried out to prepare tantalum carbide dispersion slurry; Step 2: Wet mill tungsten carbide powder (5-30% of the total weight of tungsten carbide powder) with an appropriate amount of cobalt powder in a liquid medium to prepare a tungsten carbide-cobalt mixed slurry; mix the tungsten carbide-cobalt mixed slurry with the tantalum carbide dispersion slurry obtained in Step 1 to obtain a mixed slurry; add the remaining tungsten carbide powder and forming agent to the mixed slurry and continue ball milling; Step 3: After ball milling, the material is dried, granulated, shaped, and sintered to obtain the high-toughness cemented carbide.

[0007] Preferably, the mass ratio of tantalum carbide powder, tungsten carbide powder, and cobalt powder is (1-3):1000:(58-62).

[0008] Preferably, the liquid medium is 96-98 vol% alcohol.

[0009] Preferably, in step 1, the tantalum carbide powder and the liquid medium are mixed at a solid-liquid ratio of (1-3):(20-40) g / mL.

[0010] Preferably, in step 1, the ball mill rotation speed is 250-350 r / min, the time is 8-12 h, and the ball-to-material ratio is (3-5):1.

[0011] Preferably, the dispersion treatment is ultrasonic dispersion, and the ultrasonic dispersion frequency is 50-70Hz, and the time is 20-40min.

[0012] In further detail regarding the present invention, step 1 involves independently and intensively pre-treating tantalum carbide, using the mechanical force of ball milling to refine its original particles. During the ball milling process, the milling time is controlled to avoid reverse milling, and alcohol is introduced as a liquid medium to prevent the adhesion between fine particles. Subsequently, ultrasonic dispersion treatment is used to break up the agglomerates that have reformed due to the increased surface energy of the refined particles, thereby obtaining a highly dispersed tantalum carbide slurry at the source, which is beneficial for the uniform dispersion of tantalum carbide in cemented carbide in the subsequent process.

[0013] Preferably, in step 2, the solid-liquid ratio of the tungsten carbide powder to the liquid medium is 1000:(150-250)g / mL.

[0014] Preferably, in step 2, the wet grinding is a drum ball mill with a ball-to-material ratio of (5-7):1, a rotation speed of 60-80 r / min, and a wet grinding time of 8-12 h.

[0015] Preferably, in step 2, the mixing is ball milling, and the mixing time is 0.5-5 hours.

[0016] Preferably, in step 2, the molding agent includes paraffin wax and oleic acid, the amount of paraffin wax added is 2-3% of the total weight of tungsten carbide powder, and the mass-volume ratio of paraffin wax to oleic acid is (10-12):1g / mL.

[0017] Preferably, in step 2, the ball milling time is 32-37 hours.

[0018] Further explanation of the present invention: In step 2, a portion of tungsten carbide (accounting for 5-30% of the total weight of tungsten carbide powder) and cobalt powder are pre-wet-milled to form a tungsten carbide-cobalt mixed slurry, which constitutes a liquid dispersion carrier rich in a binder phase. By mixing the tungsten carbide-cobalt mixed slurry with the tantalum carbide dispersion slurry obtained in step 1, the pre-dispersed tantalum carbide particles can be effectively captured by the carrier slurry and achieve secondary uniform distribution. Then, the remaining tungsten carbide powder and a forming agent are added to the mixed slurry, and ball milling continues. This stepwise addition of tungsten carbide powder design avoids the tungsten carbide powder, which constitutes the majority, from participating in a prolonged high-energy ball milling process, thereby effectively protecting its grains from excessive refinement and contributing to the final alloy maintaining excellent toughness while achieving a uniform microstructure.

[0019] Preferably, in step 3, the sintering method is liquid phase sintering, the sintering temperature is 1400-1450℃, and the sintering holding time is 1-3h.

[0020] Preferably, the grinding media in the ball mill is a cemented carbide ball.

[0021] The present invention also provides a high-toughness cemented carbide, which is prepared by the above-described preparation method.

[0022] Preferably, the high-toughness cemented carbide has a Vickers hardness HV10 ≥ 1510 and a fracture toughness ≥ 13.8 MPa·m. 1 / 2 .

[0023] The present invention has the following beneficial effects: 1. Compared with existing technologies, this invention provides a method for preparing high-toughness cemented carbide. First, tantalum carbide is subjected to independent ball milling and ultrasonic dispersion treatment to obtain a tantalum carbide dispersion slurry, allowing it to enter the subsequent mixing process in a highly deagglomerated state. This eliminates the potential for tantalum carbide to become a crack initiation due to primary agglomeration, providing a fundamental guarantee for improving the fracture toughness of the alloy. Then, a carrier slurry is prepared in advance using a portion of tungsten carbide powder and cobalt powder, which is then mixed with the tantalum carbide dispersion slurry. This slurry-to-slurry mixing method provides a better dispersion medium and environment for the fine tantalum carbide particles, enabling them to be uniformly fixed in the tungsten carbide and cobalt mixture. This achieves uniform distribution of tantalum carbide at the microscale, further improving the dispersibility and uniformity of tantalum carbide in the cemented carbide.

[0024] 2. Compared to existing technologies, this invention controls the proportion of tungsten carbide powder involved in the initial carrier slurry preparation and adopts a stepwise addition strategy for the remaining tungsten carbide powder. This ensures that tantalum carbide is sufficiently dispersed as a carrier while avoiding excessive grain refinement caused by prolonged ball milling of all tungsten carbide powder. The method provided by this invention cleverly balances the improvement of additive dispersibility with the maintenance of matrix grain integrity, resulting in a cemented carbide with high hardness and significantly improved fracture toughness. This invention's method has low raw material costs, a simple process, requires no special equipment, and is suitable for large-scale industrial production. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 The image shows the metallographic structure of the high-toughness cemented carbide obtained in Example 1 of this invention. Figure 2 The image shows the metallographic structure of the high-toughness cemented carbide obtained in Example 2 of this invention. Figure 3 This is a metallographic image of the high-toughness cemented carbide obtained in Example 3 of the present invention; Figure 4 The image shows the metallographic structure of the high-toughness cemented carbide obtained in Comparative Example 1 of this invention. Figure 5 The image shows the metallographic structure of the high-toughness cemented carbide obtained in Comparative Example 2 of this invention. Figure 6 The image shows the metallographic structure of the high-toughness cemented carbide obtained in Comparative Example 3 of this invention. Figure 7 The image shows the metallographic structure of the high-toughness cemented carbide obtained in Comparative Example 4 of this invention. Figure 8 The image shows the metallographic structure of the high-toughness cemented carbide obtained in Comparative Example 5 of this invention. Figure 9 This is a metallographic image of the high-toughness cemented carbide obtained in Comparative Example 6 of the present invention.

[0027] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.

[0029] This invention provides a method for preparing a high-toughness cemented carbide, comprising the following steps: Step 1: After ball milling and mixing tantalum carbide powder with liquid medium, dispersion treatment is carried out to prepare tantalum carbide dispersion slurry; Step 2: Wet mill tungsten carbide powder (5-30% of the total weight of tungsten carbide powder) with an appropriate amount of cobalt powder in a liquid medium to prepare a tungsten carbide-cobalt mixed slurry; mix the tungsten carbide-cobalt mixed slurry with the tantalum carbide dispersion slurry obtained in Step 1 to obtain a mixed slurry; add the remaining tungsten carbide powder and forming agent to the mixed slurry and continue ball milling; Step 3: After ball milling, the material is dried, granulated, shaped, and sintered to obtain the high-toughness cemented carbide.

[0030] Preferably, the mass ratio of tantalum carbide powder, tungsten carbide powder, and cobalt powder is (1-3):1000:(58-62).

[0031] Specifically, the mass ratio of tantalum carbide powder, tungsten carbide powder, and cobalt powder can be any one of 1:1000:60, 1.5:1000:60, 2:1000:60, 2.5:1000:60, 3:1000:60, or a range between two of them.

[0032] Preferably, the liquid medium is 96-98 vol% alcohol.

[0033] Preferably, in step 1, the tantalum carbide powder and the liquid medium are mixed at a solid-liquid ratio of (1-3):(20-40) g / mL.

[0034] Specifically, the tantalum carbide powder and the liquid medium can be mixed in any one of the following solid-liquid ratios or a range between two: 1:20 g / mL, 1:30 g / mL, 1:35 g / mL, 1:40 g / mL, 1.5:20 g / mL, 1.5:30 g / mL, 1.5:35 g / mL, 1.5:40 g / mL, 2:20 g / mL, 2:30 g / mL, 2:35 g / mL, 2:40 g / mL, 2.5:20 g / mL, 2.5:30 g / mL, 2.5:35 g / mL, 2.5:40 g / mL, 3:20 g / mL, 3:30 g / mL, 3:35 g / mL, 3:40 g / mL.

[0035] Preferably, in step 1, the ball mill rotation speed is 250-350 r / min, the time is 8-12 h, and the ball-to-material ratio is (3-5):1.

[0036] Specifically, the rotational speed of the ball mill can be any one of 250 r / min, 300 r / min, 350 r / min or a range between two of them; the time can be any one of 8 h, 9 h, 10 h, 11 h, 12 h or a range between two of them; and the ball-to-material ratio can be any one of 3:1, 4:1, 5:1 or a range between two of them.

[0037] Preferably, the dispersion treatment is ultrasonic dispersion, and the ultrasonic dispersion frequency is 50-70Hz, and the time is 20-40min.

[0038] Specifically, the frequency of the ultrasonic dispersion can be any one of 50Hz, 60Hz, 70Hz or a range between two of them; the time can be any one of 8h, 9h, 10h, 11h, 12h or a range between two of them.

[0039] Preferably, in step 2, the solid-liquid ratio of the tungsten carbide powder to the liquid medium is 1000:(150-250)g / mL.

[0040] Specifically, the solid-liquid ratio of the tungsten carbide powder to the liquid medium can be any one of 1000:150 g / mL, 1000:175 g / mL, 1000:200 g / mL, 1000:225 g / mL, or 1000:250 g / mL, or a range between two of them.

[0041] Preferably, in step 2, the wet grinding is a drum ball mill with a ball-to-material ratio of (5-7):1, a rotation speed of 60-80 r / min, and a wet grinding time of 8-12 h.

[0042] Specifically, the ball-to-material ratio can be any one of 5:1, 6:1, 7:1, or a range between two of them; the rotational speed can be any one of 60 r / min, 70 r / min, 80 r / min, or a range between two of them; and the wet milling time can be any one of 8 h, 9 h, 10 h, 11 h, 12 h, or a range between two of them.

[0043] Preferably, in step 2, the mixing is ball milling, and the mixing time is 0.5-5 hours.

[0044] Specifically, the mixing time can be any one of 0.5h, 1h, 2h, 3h, 4h, 5h, or a range between two of them.

[0045] Preferably, in step 2, the molding agent includes paraffin wax and oleic acid, the amount of paraffin wax added is 2-3% of the total weight of tungsten carbide powder, and the mass-volume ratio of paraffin wax to oleic acid is (10-12):1g / mL.

[0046] Specifically, the amount of paraffin added can be any one of 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3% of the total weight of tungsten carbide powder, or a range between two of these; the mass-to-volume ratio of paraffin to oleic acid can be any one of 10:1 g / mL, 11:1 g / mL, or 12:1 g / mL, or a range between two of these.

[0047] Preferably, in step 2, the ball milling time is 32-37 hours.

[0048] Specifically, the ball milling time can be any one of 32h, 33h, 34h, 35h, 36h, or 37h, or a range between two of them.

[0049] Preferably, in step 3, the sintering method is liquid phase sintering, the sintering temperature is 1400-1450℃, and the sintering holding time is 1-3h.

[0050] Specifically, the sintering temperature can be any one of 1400℃, 1430℃, 1450℃ or a range between two of them; the sintering holding time can be any one of 1h, 1.5h, 2h, 2.5h, 3h or a range between two of them.

[0051] Preferably, the grinding media in the ball mill is a cemented carbide ball.

[0052] The present invention also provides a high-toughness cemented carbide, which is prepared by the above-described preparation method.

[0053] Preferably, the high-toughness cemented carbide has a Vickers hardness HV10 ≥ 1510 and a fracture toughness ≥ 13.8 MPa·m. 1 / 2 .

[0054] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0055] Example 1 A method for preparing a high-toughness cemented carbide includes the following steps: Step 1: Add 1.5g of tantalum carbide powder and 30mL of 97vol% alcohol to a planetary ball mill and ball mill for 10h at a speed of 300r / min to prepare an alcohol slurry containing tantalum carbide. The grinding balls are cemented carbide balls with a ball-to-powder ratio of 4:1. Place the alcohol slurry containing tantalum carbide in an ultrasonic vibrator and ultrasonically disperse it for 30min at 25℃ and an ultrasonic frequency of 60Hz to obtain a tantalum carbide dispersion slurry. Step 2: Mix 100g of tungsten carbide powder, 60g of cobalt powder, and 225mL of 97vol% alcohol and ball mill at 300r / min for 10h to obtain a tungsten carbide-cobalt mixed slurry. The grinding balls are cemented carbide balls with a ball-to-material ratio of 6:1. Then, add the tantalum carbide dispersion slurry obtained in Step 1 to the tungsten carbide-cobalt mixed slurry and continue mixing and ball milling for 1h to obtain a mixed slurry. Then, add 900g of tungsten carbide powder, 22g of paraffin wax, and 2mL of oleic acid to the mixed slurry and continue mixing and ball milling for 35h. Step 3: After ball milling, dry at 120℃ for 2 hours, then granulate and pass through a 30-mesh sieve to obtain mixed material particles. Press the mixed material particles into green blanks required for metallographic analysis, hardness testing and fracture toughness testing. Place the green blanks in a sintering furnace and perform liquid phase sintering at 1430℃ for 2 hours. Then cool with the furnace to room temperature to obtain the high-toughness cemented carbide.

[0056] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this embodiment. The test results showed that the Vickers hardness (HV10) of the high-toughness cemented carbide was 1510, and the fracture toughness was 13.94 MPa·m. 1 / 2 The metallographic image of this high-toughness cemented carbide is as follows: Figure 1 As shown, by Figure 1 It can be seen that tantalum carbide is uniformly distributed in the alloy matrix, with no obvious agglomeration.

[0057] Example 2 A method for preparing a high-toughness cemented carbide includes the following steps: Step 1: Add 2g of tantalum carbide powder and 35mL of 97vol% alcohol to a planetary ball mill and ball mill for 11h at a speed of 300r / min to prepare an alcohol slurry containing tantalum carbide. The grinding balls are cemented carbide balls with a ball-to-powder ratio of 4:1. Place the alcohol slurry containing tantalum carbide in an ultrasonic vibrator and ultrasonically disperse it for 30min at 25℃ and an ultrasonic frequency of 60Hz to obtain a tantalum carbide dispersion slurry. Step 2: Mix 150g of tungsten carbide powder, 60g of cobalt powder, and 200mL of 97vol% alcohol and ball mill at 300r / min for 11h to obtain a tungsten carbide-cobalt mixed slurry. The grinding balls are cemented carbide balls with a ball-to-material ratio of 6:1. Then, add the tantalum carbide dispersion slurry obtained in Step 1 to the tungsten carbide-cobalt mixed slurry and continue mixing and ball milling for 3h to obtain a mixed slurry. Then, add 850g of tungsten carbide powder, 22g of paraffin wax, and 2mL of oleic acid to the mixed slurry and continue mixing and ball milling for 34h. Step 3: After ball milling, dry at 120℃ for 2 hours, then granulate and pass through a 30-mesh sieve to obtain mixed material particles. Press the mixed material particles into green blanks required for metallographic analysis, hardness testing and fracture toughness testing. Place the green blanks in a sintering furnace and perform liquid phase sintering at 1430℃ for 2 hours. Then cool with the furnace to room temperature to obtain the high-toughness cemented carbide.

[0058] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this embodiment. The test results showed that the Vickers hardness HV10 of the high-toughness cemented carbide was 1517, and the fracture toughness was 13.87 MPa·m. 1 / 2 The metallographic results of this high-toughness cemented carbide are as follows: Figure 2 As shown, by Figure 2 It can be seen that tantalum carbide is uniformly distributed in the alloy matrix, with no obvious agglomeration.

[0059] Example 3 A method for preparing a high-toughness cemented carbide includes the following steps: Step 1: Add 2g of tantalum carbide powder and 20mL of 97vol% alcohol to a planetary ball mill and ball mill for 8h at 300r / min to prepare an alcohol slurry containing tantalum carbide. The grinding balls are cemented carbide balls with a ball-to-powder ratio of 4:1. Place the alcohol slurry containing tantalum carbide in an ultrasonic vibrator and ultrasonically disperse it for 30min at 25℃ and 60Hz to obtain a tantalum carbide dispersion slurry. Step 2: Mix 250g of tungsten carbide powder, 60g of cobalt powder, and 250mL of 97vol% alcohol and ball mill at 300r / min for 8 hours to obtain a tungsten carbide-cobalt mixed slurry. The grinding balls are cemented carbide balls with a ball-to-material ratio of 6:1. Then, add the tantalum carbide dispersion slurry obtained in Step 1 to the tungsten carbide-cobalt mixed slurry and continue mixing and ball milling for 2.5 hours to obtain a mixed slurry. Then, add 750g of tungsten carbide powder, 22g of paraffin wax, and 2mL of oleic acid to the mixed slurry and continue mixing and ball milling for 37 hours. Step 3: After ball milling, dry at 120℃ for 2 hours, then granulate and pass through a 30-mesh sieve to obtain mixed material particles. Press the mixed material particles into green blanks required for metallographic analysis, hardness testing and fracture toughness testing. Place the green blanks in a sintering furnace and perform liquid phase sintering at 1430℃ for 2 hours. Then cool with the furnace to room temperature to obtain the high-toughness cemented carbide.

[0060] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this embodiment. The test results showed that the Vickers hardness HV10 of the high-toughness cemented carbide was 1520, and the fracture toughness was 13.81 MPa·m. 1 / 2 The metallographic results of this high-toughness cemented carbide are as follows: Figure 3 As shown, by Figure 3 It can be seen that tantalum carbide is uniformly distributed in the alloy matrix, with no obvious agglomeration.

[0061] Comparative Example 1 A method for preparing a high-toughness cemented carbide includes the following steps: Step 1: Add 1.5g of tantalum carbide powder and 30mL of 97vol% alcohol to a planetary ball mill and ball mill for 10h at a speed of 300r / min to prepare an alcohol slurry containing tantalum carbide. The grinding balls are cemented carbide balls with a ball-to-material ratio of 4:1. Step 2: Mix 100g of tungsten carbide powder, 60g of cobalt powder, and 225mL of 97vol% alcohol and ball mill at 300r / min for 10 hours to obtain a tungsten carbide-cobalt mixed slurry. The grinding balls are cemented carbide balls with a ball-to-material ratio of 6:1. Then, add the alcohol slurry containing tantalum carbide obtained in Step 1 to the tungsten carbide-cobalt mixed slurry and continue mixing and ball milling for 1 hour to obtain a mixed slurry. Then, add 900g of tungsten carbide powder, 22g of paraffin wax, and 2mL of oleic acid to the mixed slurry and continue mixing and ball milling for 35 hours. Step 3: After ball milling, dry at 120℃ for 2 hours, then granulate and pass through a 30-mesh sieve to obtain mixed material particles. Press the mixed material particles into green blanks required for metallographic analysis, hardness testing and fracture toughness testing. Place the green blanks in a sintering furnace and perform liquid phase sintering at 1430℃ for 2 hours. Then cool with the furnace to room temperature to obtain the high-toughness cemented carbide.

[0062] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this comparative example. The test results showed that the Vickers hardness HV10 of this high-toughness cemented carbide was 1485, and the fracture toughness was 11.81 MPa·m. 1 / 2 Metallographic results are as follows Figure 4 As shown, by Figure 4 It can be seen that tantalum carbide is unevenly distributed in the alloy matrix, and there is obvious agglomeration.

[0063] Comparative Example 2 A method for preparing a high-toughness cemented carbide differs from Example 1 only in step 2, which is as follows: 60g of cobalt powder and 225mL of 97vol% alcohol were mixed and ball-milled at 300r / min for 10h to obtain a cobalt-containing slurry. The grinding balls were cemented carbide balls with a ball-to-material ratio of 6:1. Then, tantalum carbide dispersion slurry obtained in step 1 was added to the cobalt-containing slurry, and the mixture was ball-milled for another 1h to obtain a mixed slurry. Then, 1000g of tungsten carbide powder, 22g of paraffin wax and 2mL of oleic acid were added to the mixed slurry, and the mixture was ball-milled for another 35h.

[0064] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this comparative example. The test results showed that the Vickers hardness (HV10) of this high-toughness cemented carbide was 1476, and the fracture toughness was 11.45 MPa·m. 1 / 2 Metallographic results are as follows Figure 5 As shown in the figure, tantalum carbide is unevenly distributed in the alloy matrix, and there is obvious agglomeration.

[0065] Comparative Example 3 A method for preparing a high-toughness cemented carbide differs from Example 1 only in that 1.5g of tantalum carbide powder in step 1 is replaced with 5g of tantalum carbide powder.

[0066] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this comparative example. The test results showed that the Vickers hardness (HV10) of this high-toughness cemented carbide was 1483, and the fracture toughness was 11.32 MPa·m. 1 / 2Metallographic results are as follows Figure 6 As shown in the figure, tantalum carbide is unevenly distributed in the alloy matrix, and there is obvious agglomeration.

[0067] Comparative Example 4 A method for preparing a high-toughness cemented carbide differs from Example 1 only in step 1, which is as follows: 1.5g of tantalum carbide powder was mixed with 30mL of 97vol% alcohol to prepare an alcohol slurry containing tantalum carbide; the alcohol slurry containing tantalum carbide was placed in an ultrasonic vibrator and ultrasonically dispersed for 30min at 25℃ and an ultrasonic frequency of 60Hz to obtain a tantalum carbide dispersion slurry.

[0068] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this comparative example. The test results showed that the Vickers hardness (HV10) of this high-toughness cemented carbide was 1487, and the fracture toughness was 11.62 MPa·m. 1 / 2 Metallographic results are as follows Figure 7 As shown, by Figure 7 It can be seen that tantalum carbide is uniformly distributed in the alloy matrix, and there is some agglomeration.

[0069] Comparative Example 5 A method for preparing a high-toughness cemented carbide differs from Example 1 only in step 2, which is as follows: 400g of tungsten carbide powder, 60g of cobalt powder, and 225mL of alcohol were mixed and ball-milled at 300r / min for 10 h to obtain a tungsten carbide-cobalt mixed slurry. The grinding balls were cemented carbide balls with a ball-to-material ratio of 6:1. Then, tantalum carbide dispersion slurry obtained in step 1 was added to the tungsten carbide-cobalt mixed slurry, and the mixture was ball-milled for another 1 h to obtain a mixed slurry. Then, 600g of tungsten carbide powder, 22g of paraffin wax, and 2mL of oleic acid were added to the mixed slurry, and the mixture was ball-milled for another 35 h.

[0070] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this comparative example. The test results showed that the Vickers hardness HV10 of this high-toughness cemented carbide was 1524, and the fracture toughness was 10.87 MPa·m. 1 / 2 Metallographic results are as follows Figure 8 As shown, by Figure 8 It can be seen that the number of small tungsten carbide particles has increased, while tantalum carbide shows no obvious agglomeration.

[0071] Comparative Example 6 A method for preparing a high-toughness cemented carbide differs from Example 1 only in that the ball milling for 10 hours in step 1 is replaced with ball milling for 20 hours.

[0072] Metallographic analysis, hardness testing, and fracture toughness testing were performed on the high-toughness cemented carbide prepared in this comparative example. The test results showed that the Vickers hardness (HV10) of this high-toughness cemented carbide was 1492, and the fracture toughness was 11.94 MPa·m. 1 / 2 Metallographic results are as follows Figure 9 As shown, by Figure 9 It can be seen that tantalum carbide is evenly distributed in the alloy matrix without obvious agglomeration, but the particle size of tantalum carbide becomes coarser.

[0073] In summary, this invention provides a high-toughness cemented carbide and its preparation method. First, tantalum carbide powder is subjected to independent high-energy ball milling and ultrasonic dispersion treatment to prepare a highly deagglomerated tantalum carbide dispersion slurry at the source, effectively eliminating the potential for tantalum carbide agglomeration to become a crack initiation point. Subsequently, a carrier slurry is pre-prepared using a portion of tungsten carbide powder and cobalt powder, and then mixed with the aforementioned tantalum carbide dispersion slurry. This slurry-to-slurry mixing method provides an excellent dispersion environment for the tantalum carbide particles, achieving their uniform distribution at the microscale. Simultaneously, the method provided by this invention controls the proportion of tungsten carbide powder involved in the preparation of the carrier slurry and adds the remaining tungsten carbide powder stepwise, ensuring sufficient dispersion of tantalum carbide while avoiding excessive refinement of the tungsten carbide grains in the matrix. The process design of this invention is ingenious, coordinating the balance between improving additive dispersibility and maintaining the integrity of the matrix grains, thereby enabling the cemented carbide prepared by this method to maintain high hardness while significantly improving its fracture toughness. The method of this invention uses readily available raw materials, has a clear process route, requires no special equipment, and has good prospects for industrial application.

[0074] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for producing a high toughness cemented carbide, characterized in that, The method comprises the following steps: Step 1, dispersing the mixture of the tantalum carbide powder and the liquid medium after ball milling to prepare a tantalum carbide dispersion slurry; Step 2, wet milling 5-30% of the total weight of the tungsten carbide powder and an appropriate amount of cobalt powder in a liquid medium to prepare a tungsten carbide-cobalt mixed slurry; mixing the tungsten carbide-cobalt mixed slurry with the tantalum carbide dispersion slurry obtained in step 1 to obtain a mixed slurry; adding the remaining tungsten carbide powder and a forming agent to the mixed slurry and continuing ball milling; Step 3, drying, granulating, forming and sintering after ball milling to obtain the high-toughness cemented carbide.

2. The production method according to claim 1, characterized by, The mass ratio of the tantalum carbide powder, the tungsten carbide powder and the cobalt powder is (1-3):1000:(58-62); the tantalum carbide powder is mixed with the liquid medium at a solid-liquid ratio of (1-3):(20-40) g / mL.

3. The preparation method according to claim 1, characterized in that, In step 1, the rotation speed of the ball milling is 250-350 r / min, the time is 8-12 h, and the ball-to-material ratio is (3-5):

1.

4. The method of claim 1, wherein, The dispersing treatment is ultrasonic dispersion, and the frequency of the ultrasonic dispersion is 50-70 Hz, and the time is 20-40 min.

5. The preparation method according to claim 1, characterized in that, In step 2, the solid-liquid ratio of the tungsten carbide powder and the liquid medium is 1000:(150-250) g / mL; the wet milling is drum ball milling, the ball-to-material ratio is (5-7):1, the rotation speed is 60-80 r / min, and the wet milling time is 8-12 h; the mixing is ball milling mixing, and the mixing time is 0.5-5 h.

6. The method of claim 1, wherein, In step 2, the forming agent comprises paraffin and oleic acid, the addition amount of the paraffin is 2-3% of the total weight of the tungsten carbide powder, and the mass-volume ratio of the paraffin and the oleic acid is (10-12):1 g / mL.

7. The preparation method according to claim 1, characterized in that, In step 2, the time of the continued ball milling is 32-37 h.

8. The method of claim 1, wherein, In step 3, the sintering is liquid phase sintering, the sintering temperature is 1400-1450℃, and the sintering holding time is 1-3 h.

9. A high toughness cemented carbide, characterized in that, The high-toughness cemented carbide is prepared by the method of any one of claims 1-8.

10. A cemented carbide according to claim 9, c h a r a c t e r i z e d in that The high toughness hard alloy has a Vickers hardness HV10≥1510 and a fracture toughness≥13.8 MPa·m 1 / 2 .

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