A preparation method for improving impact toughness of a cemented carbide and the cemented carbide

Abstract

The application belongs to the technical field of hard alloy and particularly relates to a preparation method for improving impact toughness of hard alloy and the hard alloy, and comprises the following steps: S1, obtaining tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and obtaining tungsten carbide blocks by high-temperature carbonization of the tungsten powder; S2, obtaining tungsten carbide powder by airflow crushing and airflow grading of the tungsten carbide blocks; S3, obtaining first slurry by first wet grinding of the spherical cobalt powder, adding the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry to obtain second slurry by second wet grinding; and S4, obtaining the hard alloy by drying, pressing and sintering of the second slurry; the application adopts the high-temperature carbonization process, promotes complete development of the tungsten carbide, adopts the airflow crushing and airflow grading to effectively improve the uniformity of the tungsten carbide powder, adopts the spherical cobalt powder and pre-mixes and disperses the cobalt powder first to promote uniform distribution of the cobalt phase in the hard alloy sintering process, and thus effectively improves the impact resistance of the low-cobalt hard alloy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hard alloy, and particularly relates to a preparation method for improving impact toughness of hard alloy and hard alloy. BACKGROUND

[0002] In the key application fields of tungsten carbide cobalt hard alloy (such as mine rock drilling bits, oil drilling tools, impact cutting tools, stamping dies and wear-resistant parts bearing dynamic load), impact toughness plays a decisive role. It directly determines the ability of the material to resist fracture and collapse under sudden and non-uniform impact load. Insufficient impact toughness can easily cause brittle fracture, edge collapse or overall fragmentation of the tool during service (such as when the drill bit encounters hard rock or the cutter cuts intermittently), not only causing catastrophic failure of the tool or part, significantly shortening the service life, increasing the frequency of downtime and cost, but also more likely to cause safety accidents.

[0003] The main problem existing at present is that the inherent high hardness and high wear resistance of hard alloy often restrict each other (the "hardness-toughness contradiction"); increasing the content of cobalt (Co) binder phase can improve the toughness, but at the expense of hardness and wear resistance; internal micro defects of the material (such as pores, impurities, abnormal WC grain growth, uneven Co phase distribution) can significantly become crack sources, reducing the actual toughness; optimizing toughness helps to balance the comprehensive performance of the material, giving the material better fatigue resistance and damage resistance under the premise of maintaining sufficient hardness and wear resistance, which has strategic significance for the goal of modern manufacturing to pursue high efficiency, high precision and high reliability. Therefore, a technology is needed to improve the impact toughness of WC-Co hard alloy, which can effectively control the morphology of tungsten carbide grains without increasing the Co content of the hard alloy, prevent abnormal grain growth, and simultaneously improve the impact resistance of the hard alloy. SUMMARY

[0004] To solve the above technical problems, the application provides a preparation method for improving impact toughness of hard alloy, comprising the following steps: S1, obtaining tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and carbonizing the tungsten powder at high temperature to obtain tungsten carbide blocks; S2, performing airflow crushing and airflow classification on the tungsten carbide blocks to obtain tungsten carbide powder; S3, performing first wet grinding on the spherical cobalt powder to obtain first slurry, and adding the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry to perform second wet grinding to obtain second slurry; S4, drying, pressing and sintering the second slurry to obtain hard alloy.

[0005] As a preferred scheme of the preparation method for improving impact toughness of cemented carbide provided by the application, in the step S1, the Fisher particle size of the tungsten powder is 3.2-3.4 µm, the temperature of the high-temperature carbonization is 1850-2000 ℃, and the time of the high-temperature carbonization is 120-180 min.

[0006] As a preferred scheme of the preparation method for improving impact toughness of cemented carbide provided by the application, in the step S2, the gas pressure of the air flow breaking is 8-10 mbar, and the rotating speed of the classification wheel of the air flow breaking is 1000-1600 r / min.

[0007] As a preferred scheme of the preparation method for improving impact toughness of cemented carbide provided by the application, in the step S2, the classification frequency of the air flow classification is 44-50 Hz.

[0008] As a preferred scheme of the preparation method for improving impact toughness of cemented carbide provided by the application, the step S3 further comprises: adding a dispersing agent in the process of the first wet grinding, the particle size of the spherical cobalt powder is 0.5-1.0 µm, the time of the first wet grinding is 2-4 h, and the dispersing agent comprises alcohol.

[0009] As a preferred scheme of the preparation method for improving impact toughness of cemented carbide provided by the application, in the step S3, the mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is (91.5-94.8):(5-8):(0.2-0.5).

[0010] As a preferred scheme of the preparation method for improving impact toughness of cemented carbide provided by the application, the step S3 further comprises: adding a dispersing agent and a forming agent in the process of the first wet grinding, the time of the second wet grinding is 35-40 h, the dispersing agent comprises alcohol, and the forming agent comprises paraffin.

[0011] As a preferred scheme of the preparation method for improving impact toughness of cemented carbide provided by the application, in the step S4, the temperature of the sintering is 1430-1480 ℃, the time of the sintering is 40-100 min, the pressure of the sintering is 70-120 bar, and the sintering is carried out in a hydrogen atmosphere.

[0012] The application further provides a cemented carbide prepared by the above preparation method for improving impact toughness of cemented carbide.

[0013] As a preferred scheme of the cemented carbide provided by the application, the impact toughness of the cemented carbide is greater than or equal to 7.5 J / cm 3 .

[0014] The beneficial effects of the application are as follows:

[0015] The application provides a preparation method for improving impact toughness of a hard alloy and the hard alloy, through a high-temperature carbonization process, grain boundaries between particles are effectively reduced, and tungsten carbide is promoted to develop completely, airflow crushing and airflow classification can effectively improve uniformity of tungsten carbide powder and can effectively avoid abnormal growth of tungsten carbide grains in a sintering process of the hard alloy, spherical cobalt powder is used and the cobalt powder is pre-mixed and dispersed, cobalt phases are promoted to be uniformly distributed in the sintering process of the hard alloy, and through the above process, impact resistance of the low-cobalt hard alloy can be effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0017] Figure 1 A metallographic picture of the hard alloy prepared in Example 1 in the present application;

[0018] Figure 2 A metallographic picture of the hard alloy prepared in Comparative Example 1 in the present application;

[0019] Figure 3 A metallographic picture of the hard alloy prepared in Comparative Example 2 in the present application;

[0020] Figure 4 A metallographic picture of the hard alloy prepared in Comparative Example 4 in the present application.

[0021] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] The application provides a preparation method for improving impact toughness of a hard alloy, comprising the following steps:

[0024] S1, tungsten powder, spherical cobalt powder and tantalum-niobium solid solution are obtained, and the tungsten powder is high-temperature carbonized to obtain tungsten carbide blocks;

[0025] The tungsten powder has a Fisher particle size of 3.2-3.4 µm, the high-temperature carbonization is performed at a temperature of 1850-2000 ℃ for 120-180 min;

[0026] S2, air flow crushing and air flow classification of the tungsten carbide block to obtain tungsten carbide powder;

[0027] The air flow crushing is performed at a gas pressure of 8-10 mbar, and the air flow classification is performed at a classification wheel rotation speed of 1000-1600 r / min and a classification frequency of 44-50 Hz;

[0028] S3, first wet grinding of the spherical cobalt powder to obtain a first slurry, and second wet grinding of the tungsten carbide powder, the tantalum-niobium solid solution and the first slurry to obtain a second slurry;

[0029] The spherical cobalt powder has a particle size of 0.5-1.0 µm, the first wet grinding is performed for 2-4 h, the second wet grinding is performed for 35-40 h, and the mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is (91.5-94.8):(5-8):(0.2-0.5);

[0030] S4, drying, pressing and sintering of the second slurry to obtain the cemented carbide;

[0031] The sintering is performed at a temperature of 1430-1480 ℃ for 40-100 min under a pressure of 70-120 bar in a hydrogen atmosphere;

[0032] Specifically, the sintering is performed at a temperature of any one of 1430 ℃, 1440 ℃, 1450 ℃, 1460 ℃, 1470 ℃ and 1480 ℃ or within a range between any two of them, for a time of any one of 40 min, 50 min, 60 min, 70 min, 80 min, 90 min and 100 min or within a range between any two of them, and under a pressure of any one of 70 bar, 80 bar, 90 bar, 100 bar, 110 bar and 120 bar or within a range between any two of them.

[0033] The technical solutions of the present application are further described below in combination with specific embodiments.

[0034] Embodiment 1

[0035] A preparation method for improving the impact toughness of cemented carbide, the specific preparation method comprising the following steps:

[0036] Step S1: Obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and perform high-temperature carbonization on the tungsten powder to obtain tungsten carbide blocks, wherein the tungsten powder has a Fisher particle size of 3.2 µm, the high-temperature carbonization is performed at a temperature of 1950 °C for 180 min;

[0037] Step S2: Perform airflow crushing and airflow classification on the tungsten carbide blocks to obtain tungsten carbide powder, wherein the airflow crushing is performed at a gas pressure of 10 mbar, the airflow crushing is performed at a classification wheel rotating speed of 1400 r / min, and the airflow classification is performed at a classification frequency of 50 Hz;

[0038] Step S3: Add the spherical cobalt powder into a ball mill, add alcohol to perform first wet milling to obtain first slurry, add the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry, and add paraffin and alcohol to perform second wet milling to obtain second slurry, wherein the spherical cobalt powder has a particle size of 0.8 µm, the first wet milling is performed for 3 h, the mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 91.5:8:0.5, and the second wet milling is performed for 40 h;

[0039] Step S4: Perform drying, pressing and sintering on the second slurry to obtain the cemented carbide, wherein the sintering is performed at a temperature of 1440 °C for 100 min under a pressure of 120 bar in a hydrogen atmosphere.

[0040] Please refer to Figure 1 , Figure 1 The metallographic picture of the cemented carbide prepared in Example 1 shows that the cemented carbide prepared in Example 1 has a uniform structure without abnormal long and large particles, the tungsten carbide grains are complete, and the impact toughness is 8.11 J / cm 3 .

[0041] Example 2

[0042] A preparation method for improving the impact toughness of cemented carbide, and the steps of the specific preparation method are as follows:

[0043] Step S1: Obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and perform high-temperature carbonization on the tungsten powder to obtain tungsten carbide blocks, wherein the tungsten powder has a Fisher particle size of 3.2 µm, the high-temperature carbonization is performed at a temperature of 2000 °C for 120 min;

[0044] Step S2: Perform airflow crushing and airflow classification on the tungsten carbide blocks to obtain tungsten carbide powder, wherein the airflow crushing is performed at a gas pressure of 10 mbar, the airflow crushing is performed at a classification wheel rotating speed of 1000 r / min, and the airflow classification is performed at a classification frequency of 44 Hz;

[0045] Step S3: add the spherical cobalt powder into the ball mill, then add alcohol to perform first wet milling to obtain a first slurry, add the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry, then add paraffin and alcohol to perform second wet milling to obtain a second slurry, wherein: the particle size of the spherical cobalt powder is 1.0 µm, the first wet milling time is 2 h. The mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 94.8:5:0.2, and the second wet milling time is 35 h;

[0046] Step S4: dry, press and sinter the second slurry to obtain the cemented carbide, wherein: the sintering temperature is 1430 ℃, the sintering time is 100 min, the sintering pressure is 120 bar, and the sintering is performed in a hydrogen atmosphere.

[0047] The cemented carbide prepared in Example 2 has a uniform microstructure, no abnormal long and large particles, complete tungsten carbide grain development, and an impact toughness of 7.52 J / cm 3 .

[0048] Example 3

[0049] A preparation method for improving the impact toughness of cemented carbide, the specific preparation method comprising the following steps:

[0050] Step S1: obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and carbonize the tungsten powder at high temperature to obtain tungsten carbide blocks, wherein: the Fisher particle size of the tungsten powder is 3.3 µm, the high-temperature carbonization temperature is 1900 ℃, and the high-temperature carbonization time is 150 min;

[0051] Step S2: perform airflow breaking and airflow classification on the tungsten carbide blocks to obtain tungsten carbide powder, wherein: the airflow breaking gas pressure is 9 mbar, the airflow breaking classification wheel rotating speed is 1400 r / min, and the airflow classification classification frequency is 47 Hz;

[0052] Step S3: add the spherical cobalt powder into the ball mill, then add alcohol to perform first wet milling to obtain a first slurry, add the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry, then add paraffin and alcohol to perform second wet milling to obtain a second slurry, wherein: the particle size of the spherical cobalt powder is 0.8 µm, the first wet milling time is 3 h. The mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 93.7:6:0.3, and the second wet milling time is 38 h;

[0053] Step S4: dry, press and sinter the second slurry to obtain the cemented carbide, wherein: the sintering temperature is 1460 ℃, the sintering time is 70 min, the sintering pressure is 90 bar, and the sintering is performed in a hydrogen atmosphere.

[0054] The cemented carbide prepared in Example 3 has a uniform microstructure, no abnormal long and large particles, complete tungsten carbide grain development, and an impact toughness of 7.91 J / cm3 .

[0055] Example 4

[0056] A preparation method for improving the impact toughness of cemented carbide, the specific steps of the preparation method are as follows:

[0057] Step S1: Obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and high-temperature carbonize the tungsten powder to obtain tungsten carbide blocks, wherein: the Fisher particle size of the tungsten powder is 3.4 µm, the high-temperature carbonization temperature is 1850 ℃, and the high-temperature carbonization time is 180 min;

[0058] Step S2: Airflow crush and airflow classify the tungsten carbide blocks to obtain tungsten carbide powder, wherein: the airflow crushing gas pressure is 8 mbar, the airflow crushing classification wheel rotation speed is 1600 r / min, and the airflow classification classification frequency is 50 Hz;

[0059] Step S3: Add the spherical cobalt powder into a ball mill, then add alcohol for first wet grinding to obtain a first slurry, add the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry, and then add paraffin and alcohol for second wet grinding to obtain a second slurry, wherein: the particle size of the spherical cobalt powder is 0.6 µm, the first wet grinding time is 4 h, the mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 91.8:8:0.2, and the second wet grinding time is 37 h;

[0060] Step S4: Dry, press and sinter the second slurry to obtain cemented carbide, wherein: the sintering temperature is 1480 ℃, the sintering time is 40 min, the sintering pressure is 70 bar, and the sintering is carried out in a hydrogen atmosphere.

[0061] The cemented carbide prepared in Example 4 has uniform microstructure, no abnormal long and large particles, complete tungsten carbide grain development, and impact toughness of 7.74 J / cm 3 .

[0062] Comparative Example 1

[0063] A preparation method for improving the impact toughness of cemented carbide, the specific steps of the preparation method are as follows:

[0064] Step S1: Obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and high-temperature carbonize the tungsten powder to obtain tungsten carbide blocks, wherein: the Fisher particle size of the tungsten powder is 3.2 µm, the high-temperature carbonization temperature is 1750 ℃, and the high-temperature carbonization time is 180 min;

[0065] Step S2: Airflow crush and airflow classify the tungsten carbide blocks to obtain tungsten carbide powder, wherein: the airflow crushing gas pressure is 10 mbar, the airflow crushing classification wheel rotation speed is 1400 r / min, and the airflow classification classification frequency is 50 Hz;

[0066] Step S3: add the spherical cobalt powder into the ball mill, then add alcohol to perform first wet milling to obtain a first slurry, add the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry, then add paraffin and alcohol to perform second wet milling to obtain a second slurry, wherein: the particle size of the spherical cobalt powder is 0.8 µm, the first wet milling time is 3 h. The mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 91.5:8:0.5, and the second wet milling time is 40 h;

[0067] Step S4: dry, press and sinter the second slurry to obtain the cemented carbide, wherein: the sintering temperature is 1440℃, the sintering time is 100 min, the sintering pressure is 120 bar, and the sintering is performed in a hydrogen atmosphere.

[0068] Please refer to Figure 2 , Figure 2 The metallographic picture of the cemented carbide prepared in Comparative Example 1 in the present application can be seen that the cemented carbide prepared in Comparative Example 1 has uniform structure, no abnormal long particles, complete tungsten carbide grain development, and impact toughness of 6.51 J / cm 3 .

[0069] Comparative Example 2

[0070] A preparation method for improving the impact toughness of cemented carbide, the specific preparation method steps are as follows:

[0071] Step S1: obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and carbonize the tungsten powder at high temperature to obtain tungsten carbide blocks, wherein: the Fisher particle size of the tungsten powder is 3.2 µm, the high-temperature carbonization temperature is 1950℃, and the high-temperature carbonization time is 180 min;

[0072] Step S2: ball mill the tungsten carbide blocks to pass through a 200-mesh sieve to obtain tungsten carbide powder, wherein: the ball-to-material ratio of the ball milling is 6:1, and the ball milling time is 60 min;

[0073] Step S3: add the spherical cobalt powder into the ball mill, then add alcohol to perform first wet milling to obtain a first slurry, add the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry, then add paraffin and alcohol to perform second wet milling to obtain a second slurry, wherein: the particle size of the spherical cobalt powder is 0.8 µm, the first wet milling time is 3 h. The mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 91.5:8:0.5, and the second wet milling time is 40 h;

[0074] Step S4: dry, press and sinter the second slurry to obtain the cemented carbide, wherein: the sintering temperature is 1440℃, the sintering time is 100 min, the sintering pressure is 120 bar, and the sintering is performed in a hydrogen atmosphere.

[0075] Please refer to Figure 3, Figure 3 The metallographic picture of the hard alloy prepared in Comparative Example 2 of the present application can be seen that the hard alloy prepared in Comparative Example 2 has abnormal long particles, the tungsten carbide grain has poor integrity, and the impact toughness is 5.84 J / cm 3 .

[0076] Comparative Example 3

[0077] A preparation method for improving the impact toughness of the hard alloy, and the specific preparation method steps are as follows:

[0078] Step S1: obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and high-temperature carbonize the tungsten powder to obtain a tungsten carbide block, wherein the tungsten powder has a Fisher particle size of 3.2 µm, the high-temperature carbonization temperature is 1950℃, and the high-temperature carbonization time is 180 min;

[0079] Step S2: air flow crush and air flow classify the tungsten carbide block to obtain tungsten carbide powder, wherein the air flow crushing gas pressure is 10 mbar, the air flow crushing classification wheel rotation speed is 1400 r / min, and the air flow classification classification frequency is 50 Hz;

[0080] Step S3: add the tungsten carbide powder, the spherical cobalt powder and the tantalum-niobium solid solution into a ball mill, and then add paraffin and alcohol for wet milling to obtain a mixed slurry, wherein the particle size of the spherical cobalt powder is 0.8 µm, the mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 91.5:8:0.5, and the wet milling time is 43 h;

[0081] Step S4: dry, press and sinter the mixed slurry to obtain a hard alloy, wherein the sintering temperature is 1440℃, the sintering time is 100 min, the sintering pressure is 120 bar, and the sintering is carried out in a hydrogen atmosphere.

[0082] The hard alloy prepared in Comparative Example 3 has uniform microstructure, relatively poor cobalt phase distribution, no abnormal long particles, and general tungsten carbide grain integrity, and the impact toughness is 6.26 J / cm 3 .

[0083] Comparative Example 4

[0084] A preparation method for improving the impact toughness of the hard alloy, and the specific preparation method steps are as follows:

[0085] Step S1: obtain tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and high-temperature carbonize the tungsten powder to obtain a tungsten carbide block, wherein the tungsten powder has a Fisher particle size of 3.2 µm, the high-temperature carbonization temperature is 1950℃, and the high-temperature carbonization time is 180 min;

[0086] Step S2: the tungsten carbide block is subjected to airflow breaking and is passed through a 325 mesh screen to obtain tungsten carbide powder, wherein: the gas pressure of the airflow breaking is 10 mbar, and the rotational speed of the classification wheel of the airflow breaking is 1400 r / min;

[0087] Step S3: spherical cobalt powder is added to a ball mill, and alcohol is added to perform first wet grinding to obtain a first slurry, and the tungsten carbide powder and the tantalum-niobium solid solution are added to the first slurry, and paraffin and alcohol are added to perform second wet grinding to obtain a second slurry, wherein: the particle size of the spherical cobalt powder is 0.8 µm, the first wet grinding time is 3 h, the mass ratio of the tungsten carbide, the spherical cobalt powder and the tantalum-niobium solid solution is 91.5:8:0.5, and the second wet grinding time is 40 h;

[0088] Step S4: the second slurry is dried, pressed and sintered to obtain the cemented carbide, wherein: the sintering temperature is 1440 ℃, the sintering time is 100 min, the sintering pressure is 120 bar, and the sintering is performed in a hydrogen atmosphere.

[0089] Please refer to Figure 4 , Figure 4 The metallographic picture of the cemented carbide prepared in Comparative Example 4 in the present application can be seen to show that the cemented carbide prepared in Comparative Example 4 has abnormal long and large particles, the tungsten carbide grains are completely developed, and the impact toughness is 5.98 J / cm 3 .

[0090] From the above examples and comparative examples, it can be seen that: Example 4 combined with Comparative Example 1 shows that the lower the carbonization temperature, the less hardness of the prepared tungsten carbide powder, and the tungsten carbide powder is easily broken in the wet grinding process to produce more fine particles, thereby resulting in more fine particles in the alloy sintering process, poor uniformity of the structure, and easy to cause abnormal growth and aggregation of tungsten carbide grains in the sintering process, thereby reducing the impact toughness; Example 4 combined with Comparative Example 2 shows that the tungsten carbide prepared by high-temperature process is seriously sintered, and the breaking effect of the ball milling process is not good. The use of airflow breaking can improve the uniformity of the powder while opening the agglomerated pseudo-particles, thereby reducing the number of fine particles produced in the wet grinding process, reducing the dissolution and precipitation amount of tungsten carbide in the sintering process, and avoiding the abnormal growth of tungsten carbide grains; Example 4 combined with Comparative Example 3 shows that the use of spherical cobalt powder and pre-mixing and dispersing of the cobalt powder can effectively improve the uniform dispersion of the cobalt powder and the full mixing with the tungsten carbide, thereby improving the uniform distribution of the cobalt phase in the sintering process and improving the impact resistance of the low-cobalt cemented carbide; Example 4 combined with Comparative Example 4 shows that the classification of the tungsten carbide particles after airflow breaking can effectively remove the fine powder produced in the airflow breaking, thereby improving the uniformity of the powder and effectively avoiding the abnormal growth of tungsten carbide grains in the sintering process of the cemented carbide; it can be seen from the above examples and comparative examples that the preparation method for improving the impact toughness of the cemented carbide can effectively improve the impact resistance of the low-cobalt cemented carbide without changing the cobalt content of the cemented carbide, and the impact toughness can reach 7.5 J / cm 3 .

[0091] The application provides a preparation method for improving the impact toughness of a cemented carbide and the cemented carbide. The high-temperature carbonization process is used to effectively reduce the grain boundaries between particles, promote the development of tungsten carbide, the airflow breaking and airflow classification can effectively improve the uniformity of the tungsten carbide powder and effectively avoid the abnormal growth of tungsten carbide grains in the sintering process of the cemented carbide, the spherical cobalt powder is used and the cobalt powder is pre-mixed and dispersed to promote the uniform distribution of the cobalt phase in the sintering process of the cemented carbide, and the above processes can effectively improve the impact resistance of the low-cobalt cemented carbide.

[0092] The above only describes the preferred embodiments of the application, and does not limit the patent scope of the application, and any equivalent structural transformation or direct / indirect application in other related technical fields made by using the content of the application description is included in the patent protection scope of the application.

Claims

1. A production method for improving impact toughness of a cemented carbide, characterized by, The method comprises the following steps: S1, obtaining tungsten powder, spherical cobalt powder and tantalum-niobium solid solution, and performing high-temperature carbonization on the tungsten powder to obtain tungsten carbide blocks, wherein the temperature of the high-temperature carbonization is 1850-2000 ℃, and the time of the high-temperature carbonization is 120-180 min; S2, performing airflow crushing and airflow classification on the tungsten carbide blocks to obtain tungsten carbide powder; S3, performing first wet grinding on the spherical cobalt powder to obtain first slurry, and adding the tungsten carbide powder and the tantalum-niobium solid solution into the first slurry to perform second wet grinding to obtain second slurry; S4, performing drying, pressing and sintering on the second slurry to obtain the cemented carbide.

2. The production method for improving impact toughness of cemented carbide according to claim 1, characterized in that, In the step S1, the Fisher particle size of the tungsten powder is 3.2-3.4 µm.

3. The method of claim 1, wherein the cemented carbide has a binder phase of Co, Fe, Ni, or a mixture thereof. In the step S2, the gas pressure of the airflow crushing is 8-10 mbar, and the rotating speed of the classification wheel of the airflow crushing is 1000-1600 r / min.

4. The method of claim 1, wherein the cemented carbide has a toughness of at least 15 MPaVm. In the step S2, the classification frequency of the airflow classification is 44-50 Hz.

5. The method of claim 1, wherein the cemented carbide has a toughness of at least 15 MPaVm. In the step S3, a dispersing agent is added during the first wet grinding, the particle size of the spherical cobalt powder is 0.5-1.0 µm, the time of the first wet grinding is 2-4 h, and the dispersing agent comprises alcohol.

6. The method of claim 1, wherein the cemented carbide has a toughness of at least 15 MPaVm. In the step S3, the mass ratio of the tungsten carbide powder, the spherical cobalt powder and the tantalum-niobium solid solution is (91.5-94.8):(5-8):(0.2-0.5).

7. The method of claim 1, wherein the cemented carbide has a toughness of at least 15 MPaVm. In the step S3, a dispersing agent and a forming agent are added during the first wet grinding, the time of the second wet grinding is 35-40 h, the dispersing agent comprises alcohol, and the forming agent comprises paraffin.

8. The method of claim 1, wherein the cemented carbide has a toughness of at least 15 MPaVm. In the step S4, the temperature of the sintering is 1430-1480 ℃, the time of the sintering is 40-100 min, the pressure of the sintering is 70-120 bar, and the sintering is performed in a hydrogen atmosphere.

9. A cemented carbide, characterized in that, The cemented carbide is prepared by the method for improving the impact toughness of the cemented carbide according to any one of claims 1-8.

10. A cemented carbide according to claim 9, characterised in that, The impact toughness of the cemented carbide is greater than or equal to 7.5 J / cm 3 .

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