Coarse-grained cemented carbide and preparation method thereof

Abstract

The present invention belongs to the technical field of powder metallurgy, and specifically relates to a coarse-grained cemented carbide and a preparation method thereof. By forming a brittle tungsten-cobalt compound, the tungsten-cobalt compound is uniformly distributed during ball milling, and then a cobalt phase is formed through in-situ reduction and carbonization, thereby achieving a coarse-grained cemented carbide with a uniform distribution of the cobalt phase. At the same time, the use of the brittle tungsten-cobalt compound can achieve a uniform mixing state in a relatively short time, thereby ensuring the particle size of the coarse-grained WC and obtaining a uniform distribution of the cobalt phase. The average grain size of the WC in the prepared coarse-grained cemented carbide is 7.0 to 9.0 μm, the hardness value is ≥1170 HV10, and the bending strength is ≥2380 MPa.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a coarse-grained cemented carbide and a preparation method thereof. Background Art

[0002] Cemented carbide is a composite material produced by powder metallurgy, consisting of a refractory metal compound as the hard phase and a transition metal with good wettability as the binder phase. It is the most important material product produced by powder metallurgy. Refractory metal compounds are typically carbides such as WC, TiC, TaC, NbC, VC, Cr2C3, and MoC, with WC being the most widely used. The binder metals of cemented carbide are primarily Co, Ni, and Fe, with Co being the most widely used. During the preparation of cemented carbide, cobalt is difficult to mill uniformly, resulting in uneven distribution of the binder phase Co in ultra-coarse cemented carbide. Increasing the milling time further refines the WC grains, reducing the grain size of the cemented carbide. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a coarse-grained cemented carbide and a preparation method thereof.

[0004] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0005] A method for preparing coarse-grained cemented carbide, wherein the average grain size of WC in the coarse-grained cemented carbide is 7.0 to 9.0 μm, comprises the following steps:

[0006] S1. Cobalt oxide, tungsten oxide and carbon black are ball-milled in a mass ratio of (35-40): (45-55): (8-15) to obtain a cobalt-containing mixture;

[0007] S2. The cobalt-containing mixture is sintered to obtain a sintered material;

[0008] S3. The sintered material was ball-milled and sieved to obtain a tungsten-cobalt compound;

[0009] S4. According to the mass percentage of cemented carbide, ultra-coarse WC powder, tungsten-cobalt compound, and carbon black are weighed and mixed, and then 1.5 to 2.2% of paraffin wax is added to the ultra-coarse WC powder, tungsten-cobalt compound, and carbon black by mass, and the ball-to-material ratio is (6 to 12): 1, the ball mill speed is 250 to 500 r / min, the ball milling time is 2 to 6 h, dried, and sieved to obtain a mixture;

[0010] S5. Pressing and sintering the mixture to obtain a coarse-grained cemented carbide with uniformly distributed WC and Co phases.

[0011] As a preferred embodiment of the method for preparing coarse-grained cemented carbide according to the present invention, in step S1, cemented carbide balls are used as grinding balls, the ball milling time is 24 to 48 hours, the ball-to-material ratio is (6 to 12):1, and the ball milling speed is 250 to 500 r / min.

[0012] As a preferred embodiment of the method for preparing coarse-grained cemented carbide according to the present invention, in step S1, the cobalt oxide is at least one of Co2O3 and Co3O4.

[0013] As a preferred embodiment of the method for preparing a coarse-grained cemented carbide according to the present invention, in step S1, the tungsten oxide is yellow tungsten (WO3), blue tungsten (WO 2.9 ), purple tungsten (WO 2.72 ) at least one of.

[0014] As a preferred embodiment of the method for preparing coarse-grained cemented carbide according to the present invention, in step S2, the sintering process is as follows: heating to 1100°C at a rate of 10°C / min, keeping the temperature for 90 to 150 minutes, and then cooling with the furnace.

[0015] As a preferred embodiment of the method for preparing coarse-grained cemented carbide described in the present invention, in step S2, nitrogen is introduced for 5 minutes before the sintering process, and then the temperature is raised to 300°C at a rate of 15-20°C / min and kept warm for 30 minutes; ensuring that the material temperature is uniform before reduction occurs; and converting the nitrogen into hydrogen after the heat preservation.

[0016] As a preferred embodiment of the method for preparing coarse-grained cemented carbide according to the present invention, in step S3, the ball-to-material ratio of ball milling is (6-12):1, the ball milling speed is 250-500 r / min, and the ball milling time is 6-12 h.

[0017] As a preferred embodiment of the method for preparing coarse-grained cemented carbide according to the present invention, in step S3, a sieve with a mesh size of 140 to 200 is used for screening.

[0018] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0019] A coarse-grained cemented carbide is prepared by adopting the above preparation method.

[0020] As a preferred embodiment of the coarse-grained cemented carbide of the present invention, the hardness of the coarse-grained cemented carbide is ≥1170HV10, and the bending strength is ≥2380MPa.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention provides a coarse-grained cemented carbide and a preparation method thereof. By forming a brittle tungsten-cobalt compound, the tungsten-cobalt compound is uniformly distributed during ball milling, and then a cobalt phase is formed through in-situ reduction and carbonization, thereby achieving a coarse-grained cemented carbide with a uniform distribution of the cobalt phase. At the same time, the use of the brittle tungsten-cobalt compound can achieve a uniform mixing state in a relatively short time, thereby ensuring the particle size of the coarse-grained WC and achieving a uniform distribution of the cobalt phase. The average grain size of the WC in the prepared coarse-grained cemented carbide is 7.0 to 9.0 μm, the hardness value is ≥1170 HV10, and the bending strength is ≥2380 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0024] Figure 1 This is a picture of the coarse-grained cemented carbide prepared in Example 1 of the present invention;

[0025] Figure 2 This is a picture of the cemented carbide prepared in Comparative Example 1 of the present invention;

[0026] Figure 3 This is a picture of the cemented carbide prepared in Comparative Example 2 of the present invention;

[0027] Figure 4 This is a picture of the cemented carbide prepared in Comparative Example 4 of the present invention;

[0028] Figure 5 This is a picture of the cemented carbide prepared in Comparative Example 6 of the present invention. DETAILED DESCRIPTION

[0029] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0031] A method for preparing coarse-grained cemented carbide, wherein the average grain size of WC in the coarse-grained cemented carbide is 7.0 to 9.0 μm, comprises the following steps:

[0032] S1. Cobalt oxide, tungsten oxide and carbon black are ball-milled in a mass ratio of (35-40): (45-55): (8-15) to obtain a cobalt-containing mixture;

[0033] S2. The cobalt-containing mixture is sintered to obtain a sintered material;

[0034] S3. The sintered material was ball-milled and sieved to obtain a tungsten-cobalt compound;

[0035] S4. According to the mass percentage of cemented carbide, ultra-coarse WC powder, tungsten-cobalt compound, and carbon black are weighed and mixed, and then 1.5 to 2.2% of paraffin wax is added to the ultra-coarse WC powder, tungsten-cobalt compound, and carbon black by mass, and the ball-to-material ratio is (6 to 12): 1, the ball mill speed is 250 to 500 r / min, the ball milling time is 2 to 6 h, dried, and sieved to obtain a mixture;

[0036] S5. Pressing and sintering the mixture to obtain a coarse-grained cemented carbide with uniformly distributed WC and Co phases.

[0037] Preferably, in step S1, the grinding balls are cemented carbide balls, the ball milling time is 24 to 48 hours, the ball-to-material ratio is (6 to 12):1, and the ball milling speed is 250 to 500 r / min. Specifically, the ball milling time can be, for example, but not limited to, any one of 24 hours, 30 hours, 36 hours, 42 hours, and 48 hours, or a range between any two of them; the ball-to-material ratio can be, for example, but not limited to, any one of 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, and 12:1, or a range between any two of them; and the ball milling speed can be, for example, but not limited to, any one of 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, and 500 r / min, or a range between any two of them.

[0038] Preferably, in step S1, the cobalt oxide is at least one of Co2O3 and Co3O4; the tungsten oxide is yellow tungsten (WO3), blue tungsten (WO 2.9 ), purple tungsten (WO 2.72 ) at least one of.

[0039] Preferably, in step S2, the sintering process is: heating to 1100°C at 10°C / min, keeping the temperature for 90 to 150 minutes, and then cooling with the furnace.

[0040] Preferably, in step S2, before the sintering process, nitrogen is introduced for 5 minutes, and then the temperature is raised to 300°C at a rate of 15-20°C / min and kept warm for 30 minutes; ensuring that the material temperature is uniform before reduction occurs; and converting the nitrogen into hydrogen after keeping warm.

[0041] Preferably, in step S3, the ball-to-material ratio of ball milling is (6-12):1, the ball milling speed is 250-500 r / min, and the ball milling time is 6-12 h. Specifically, the ball-to-material ratio of ball milling can be, for example, but not limited to, any one of 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, and 12:1, or a range between any two thereof; the ball milling speed can be, for example, but not limited to, any one of 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, and 500 r / min, or a range between any two thereof; and the ball milling time can be, for example, but not limited to, any one of 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, and 12 h, or a range between any two thereof.

[0042] Preferably, in step S3, a sieve with a mesh size of 140 to 200 is used for screening.

[0043] Preferably, in step S3, the amount of paraffin added can be, for example but not limited to, any one of 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2% of the sum of the mass of ultra-coarse WC powder, tungsten-cobalt compound, and carbon black, or a range between any two of them; the ball-to-material ratio can be, for example but not limited to, any one of 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, or a range between any two of them; the ball milling speed can be, for example but not limited to, any one of 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, or a range between any two of them; the ball milling time can be, for example but not limited to, any one of 2 h, 3 h, 4 h, 5 h, 6 h, or a range between any two of them.

[0044] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0045] A coarse-grained cemented carbide is prepared by the above preparation method; the hardness value of the coarse-grained cemented carbide is ≥1170HV10, and the bending strength is ≥2380MPa.

[0046] The technical solution of the present invention is further described below with reference to specific embodiments.

[0047] Example 1

[0048] A method for preparing coarse-grained cemented carbide comprises the following steps:

[0049] S1. Co3O4, WO3 and carbon black were ball-milled in a mass ratio of 38:50:12 using carbide balls for 24 h at a ball-to-material ratio of 6:1 at a milling speed of 350 r / min to obtain a cobalt-containing mixture.

[0050] S2. The cobalt-containing mixture was sintered in a molybdenum wire furnace by introducing nitrogen for 5 minutes, then heating to 300°C at a rate of 15°C / min, then holding at 300°C for 30 minutes. The nitrogen was then converted to hydrogen, and the temperature was further increased at a rate of 10°C / min to 1100°C, held for 120 minutes, and then cooled in the furnace to obtain a sintered material.

[0051] S3. The sintered material was ball milled, the ball-to-material ratio was 9:1, the ball mill speed was 350r / min, the ball milling time was 9h, and sieved through 140 mesh to obtain a tungsten-cobalt compound;

[0052] S4. According to the mass percentage of WC-10Co cemented carbide, ultra-coarse WC powder, tungsten-cobalt compound, and carbon black were weighed and mixed. Then, paraffin wax accounting for 1.8% of the total mass of ultra-coarse WC powder, tungsten-cobalt compound, and carbon black was added for ball milling. The ball-to-material ratio was 6:1, the ball milling speed was 350 r / min, the ball milling time was 4 h, and the mixture was dried and sieved to obtain a mixture.

[0053] S5. The mixture is pressed and sintered to obtain a coarse-grained cemented carbide, such as Figure 1 As shown, the WC phase and Co phase of the alloy are evenly distributed, the average grain size of WC is 8.1μm, its hardness value is 1364HV10, and its bending strength is 2579MPa.

[0054] Example 2

[0055] The difference from Example 1 is that

[0056] In step S1, Co3O4, WO3 and carbon black are ball-milled and mixed in a mass ratio of 35:55:10.

[0057] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 7.9 μm, the hardness is 1245 HV10, and the bending strength is 2654 MPa.

[0058] Example 3

[0059] The difference from Example 1 is that

[0060] In step S1, Co3O4, WO3 and carbon black are ball-milled and mixed in a mass ratio of 40:45:15.

[0061] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 7.7 μm, the hardness is 1425 HV10, and the bending strength is 2435 MPa.

[0062] Example 4

[0063] The difference from Example 1 is that

[0064] In step S1, Co2O3, WO3 and carbon black are ball-milled and mixed in a mass ratio of 38:50:12.

[0065] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.0 μm, the hardness is 1320 HV10, and the bending strength is 2489 MPa.

[0066] Example 5

[0067] The difference from Example 1 is that

[0068] In step S1, Co3O4, WO 2.9 The mixture was ball-milled with carbon black in a mass ratio of 38:50:12.

[0069] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.2 μm, the hardness is 1421 HV10, and the bending strength is 2528 MPa.

[0070] Example 6

[0071] The difference from Example 1 is that

[0072] In step S1, the ball milling time is 24 h, the ball-to-material ratio is 6:1, and the ball milling speed is 250 r / min.

[0073] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.4 μm, the hardness is 1253 HV10, and the bending strength is 2470 MPa.

[0074] Example 7

[0075] The difference from Example 1 is that

[0076] In step S1, the ball milling time is 48 h, the ball-to-material ratio is 12:1, and the ball milling speed is 500 r / min.

[0077] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.1 μm, the hardness is 1230 HV10, and the bending strength is 2490 MPa.

[0078] Example 8

[0079] The difference from Example 1 is that

[0080] In step S2, the temperature is further increased at a rate of 10°C / min to 1100°C and kept at this temperature for 90 minutes.

[0081] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.0 μm, the hardness is 1260 HV10, and the bending strength is 2432 MPa.

[0082] Example 9

[0083] The difference from Example 1 is that

[0084] In step S2, the temperature is further increased at a rate of 10°C / min to 1100°C and kept at this temperature for 150 minutes.

[0085] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.2 μm, the hardness is 1322 HV10, and the bending strength is 2380 MPa.

[0086] Example 10

[0087] The difference from Example 1 is that

[0088] In step S3, the ball-to-material ratio is 6:1, the ball milling speed is 250 r / min, and the ball milling time is 6 h.

[0089] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 7.5 μm, the hardness is 1190 HV10, and the bending strength is 2572 MPa.

[0090] Example 11

[0091] The difference from Example 1 is that

[0092] In step S3, the ball-to-material ratio is 12:1, the ball milling speed is 500 r / min, and the ball milling time is 12 h.

[0093] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 7.6 μm, the hardness value is 1486 HV10, and the bending strength is 2393 MPa.

[0094] Example 12

[0095] The difference from Example 1 is that

[0096] In step S4, paraffin wax accounting for 1.5% of the total mass of the super coarse WC powder, the tungsten-cobalt compound, and the carbon black is added for ball milling.

[0097] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.0 μm, the hardness is 1318 HV10, and the bending strength is 2554 MPa.

[0098] Example 13

[0099] The difference from Example 1 is that

[0100] In step S4, paraffin wax accounting for 2.2% of the total mass of the super coarse WC powder, the tungsten-cobalt compound, and the carbon black is added for ball milling.

[0101] The WC phase and the Co phase of the prepared alloy are uniformly distributed, the average grain size of WC is 8.0 μm, the hardness value is 1364 HV10, and the bending strength is 2520 MPa.

[0102] Example 14

[0103] The difference from Example 1 is that

[0104] In step S4, the ball-to-material ratio is 6:1, the ball milling speed is 250 r / min, and the ball milling time is 2 h.

[0105] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 8.5 μm, the hardness is 1275 HV10, and the bending strength is 2697 MPa.

[0106] Example 15

[0107] The difference from Example 1 is that

[0108] In step S4, the ball-to-material ratio is 12:1, the ball milling speed is 500 r / min, and the ball milling time is 6 h.

[0109] The WC phase and the Co phase of the prepared alloy are evenly distributed, the average grain size of WC is 7.3 μm, the hardness value is 1468 HV10, and the bending strength is 2551 MPa.

[0110] Comparative Example 1

[0111] A method for preparing cemented carbide, comprising:

[0112] Taking WC-10Co cemented carbide as the target product, ultra-coarse WC powder, Co powder, W powder or carbon black are weighed according to mass percentage, and the amount of paraffin added is 1.8% of the total mass of the ultra-coarse WC powder, Co powder, W powder or carbon black. The weighed ultra-coarse WC powder, Co powder, W powder or carbon black, and paraffin are added to a ball mill and ball milled using a wet milling process at a ball mill speed of 250 r / min for 2 hours. After the ball milling is completed, the ball milled product is dried, sieved, pressed and sintered to prepare a cemented carbide such as Figure 2 As shown, the WC phase and Co phase of the alloy are unevenly distributed, the average WC grain size is 8.3μm, the hardness value is 1090HV10, and the bending strength is 2248MPa.

[0113] Comparative Example 2

[0114] A method for preparing cemented carbide, comprising:

[0115] Taking WC-10Co cemented carbide as the target product, ultra-coarse WC powder, Co powder, W powder or carbon black are weighed according to mass percentage, and the amount of paraffin added is 1.8% of the total mass of the ultra-coarse WC powder, Co powder, W powder or carbon black. The weighed ultra-coarse WC powder, Co powder, W powder or carbon black, and paraffin are added to a ball mill and wet milled at a speed of 500 r / min for 6 hours. After the ball milling is completed, the ball milled product is dried, sieved, pressed and sintered to prepare a cemented carbide such as Figure 3 As shown, the WC phase and Co phase of the alloy are unevenly distributed, the average WC grain size is 4.4μm, the hardness value is 1280HV10, and the bending strength is 2285MPa.

[0116] Comparative Example 3

[0117] A method for preparing cemented carbide, comprising:

[0118] Taking WC-10Co cemented carbide as the target product, ultra-coarse WC powder, Co powder, W powder, or carbon black were weighed by mass percentage, and paraffin wax was added in an amount of 1.8% of the total mass of the ultra-coarse WC powder, Co powder, W powder, or carbon black. The weighed ultra-coarse WC powder, Co powder, W powder, or carbon black, and paraffin wax were added to a ball mill and wet-milled at a speed of 350 r / min for 4 hours. After the milling, the resulting ball-milled product was dried, sieved, pressed, and sintered to produce a cemented carbide. The alloy had a non-uniform distribution of WC and Co phases, an average WC grain size of 4.6 μm, a hardness of 1220 HV10, and a flexural strength of 2281 MPa.

[0119] Comparative Example 4

[0120] The difference from Example 1 is that

[0121] In step S1, Co3O4, WO3 and carbon black are ball-milled and mixed in a mass ratio of 34:56:7.

[0122] The alloys prepared are Figure 4 As shown, the alloy has decarburized phase, WC phase and Co phase are unevenly distributed, the average WC grain size is 4.9μm, its hardness value is 1390HV10, and its bending strength is 1585MPa.

[0123] Comparative Example 5

[0124] The difference from Example 1 is that

[0125] In step S1, Co3O4, WO3 and carbon black are ball-milled and mixed in a mass ratio of 35:45:20.

[0126] The prepared alloy showed decarburized phase, uneven distribution of WC phase and Co phase, average WC grain size of 4.7 μm, hardness of 960 HV10, and bending strength of 1638 MPa.

[0127] Comparative Example 6

[0128] The difference from Example 1 is that

[0129] In step S4, the ball-to-material ratio is 4:1, the ball milling speed is 220 r / min, and the ball milling time is 2 h.

[0130] The alloys prepared are Figure 5 As shown, the WC phase and Co phase of the alloy are severely unevenly distributed, the average WC grain size is 6.6μm, the hardness value is 1150HV10, and the bending strength is 2164MPa.

[0131] The present invention forms a brittle tungsten-cobalt compound so that the tungsten-cobalt compound is evenly distributed during the ball milling process, and then forms a cobalt phase through in-situ reduction and carbonization, thereby achieving a coarse-grained cemented carbide with a uniform distribution of the cobalt phase. At the same time, the use of the brittle tungsten-cobalt compound can achieve a uniform mixing state in a relatively short time, thereby ensuring the particle size of the coarse-grained WC and obtaining a uniform distribution of the cobalt phase. The average grain size of the WC in the prepared coarse-grained cemented carbide is 7.0 to 9.0 μm, the hardness value is ≥1170 HV10, and the bending strength is ≥2380 MPa.

[0132] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing coarse-grained cemented carbide, characterized in that: The steps include: S1. Cobalt oxide, tungsten oxide, and carbon black are ball-milled in a mass ratio of (35-40):(45-55):(8-15) to obtain a cobalt-containing mixture; S2. The cobalt-containing mixture is sintered to obtain a sintered material; S3. The sintered material was ball-milled and sieved to obtain a tungsten-cobalt compound; S4. Weigh the ultra-coarse WC powder, tungsten-cobalt compound, and carbon black according to the mass percentage of cemented carbide, then add paraffin wax accounting for 1.5-2.2% of the sum of the mass of ultra-coarse WC powder, tungsten-cobalt compound, and carbon black for ball milling. The ball-to-material ratio is (6-12):1, the ball mill speed is 250-500 r / min, the ball milling time is 2-6 h, and the mixture is dried and sieved to obtain a mixture; S5. The mixture is pressed and sintered to obtain a coarse-grained cemented carbide in which WC phase and Co phase are uniformly distributed, wherein the average grain size of WC in the coarse-grained cemented carbide is 7.0-9.0 μm, the hardness value is ≥1170 HV10, and the bending strength is ≥2380 MPa.

2. The method for preparing coarse-grained cemented carbide according to claim 1, characterized in that: In step S1, the grinding balls are cemented carbide balls, the ball milling time is 24-48 hours, the ball-to-material ratio is (6-12):1, and the ball milling speed is 250-500 r / min.

3. The method for preparing coarse-grained cemented carbide according to claim 1, characterized in that: In step S1, the cobalt oxide is at least one of Co2O3 and Co3O4.

4. The method for preparing coarse-grained cemented carbide according to claim 1, characterized in that: In step S1, the tungsten oxide is at least one of yellow tungsten, blue tungsten, and purple tungsten.

5. The method for preparing coarse-grained cemented carbide according to claim 1, characterized in that: In step S2, the sintering process is as follows: heating to 1100° C. at a rate of 10° C. / min, keeping the temperature for 90 to 150 minutes, and then cooling with the furnace.

6. The method for preparing coarse-grained cemented carbide according to claim 1, characterized in that: In step S2, before the sintering process, nitrogen is introduced for 5 minutes, and then the temperature is raised to 300°C at a rate of 15-20°C / min and kept at this temperature for 30 minutes; after the heat preservation, the nitrogen is converted into hydrogen.

7. The method for preparing coarse-grained cemented carbide according to claim 1, characterized in that: In step S3, the ball-to-material ratio of the ball milling is (6-12):1, the ball milling speed is 250-500 r / min, and the ball milling time is 6-12 h.

8. The method for preparing coarse-grained cemented carbide according to claim 1, characterized in that: In step S3, a 140-200 mesh sieve is used for sieving.

9. A coarse-grained cemented carbide, characterized in that: The preparation method is described in any one of claims 1 to 8.

Images