A method for preparing cemented carbide rods by adding cobalt carbonate

Abstract

This invention relates to the field of cemented carbide technology, specifically to a method for preparing cemented carbide rods by adding cobalt carbonate. The method provided in this application involves mixing cobalt carbonate raw material with ball milling media, performing wet ball milling, sieving, and drying for later use; adding a portion of cobalt carbonate to the raw material, with the mass ratio of cobalt carbonate to (cobalt + cobalt carbonate) being 1-4.3%; adding the prepared raw material to ball milling media and performing wet ball milling to prepare a mixed slurry; drying: drying the mixed slurry to obtain a mixture, and pressing the mixture into a cemented carbide billet; sintering the billet under low pressure and cooling it in a furnace to obtain cemented carbide rods. This method, by adding CoCO3 powder to replace part of the Co powder in the feed, can prepare cemented carbide without pores and with excellent performance. This process can reduce costs, promote green metallurgy, and reduce carbon emissions during the metallurgical process.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, and more specifically to a method for preparing cemented carbide rods by adding cobalt carbonate. Background Technology

[0002] Cemented carbide is produced by high-temperature sintering of a hard phase (WC) and a binder phase (Co) using powder metallurgy. It possesses high hardness, high toughness, high elastic modulus, and high wear resistance, and is widely used in machining, aerospace, mining, and transportation. In industrial production, the binder phase cobalt is primarily obtained by reducing cobalt powder with cobalt oxalate or cobalt oxide using hydrogen. With increasing global emphasis on carbon emission control, low-carbon metallurgy is gaining importance, making it crucial to reduce energy consumption throughout the cemented carbide production process. Therefore, researching the raw materials and preparation methods for cemented carbide rods is essential to providing a method that reduces energy consumption and production costs while simultaneously yielding cemented carbide with superior performance. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing cemented carbide rods by adding cobalt carbonate. This method involves adding CoCO3 powder to replace part of the Co powder in the feed, which can produce cemented carbide without pores and with excellent performance. This process can reduce costs, promote green metallurgy, and reduce carbon emissions in the metallurgical process.

[0004] To achieve the above objectives, the present invention provides a method for preparing cemented carbide rods by adding cobalt carbonate, comprising the following steps:

[0005] S1. Cobalt carbonate pre-ball milling: After mixing cobalt carbonate raw material with ball milling media, wet ball milling is performed, followed by sieving and drying for later use.

[0006] S2. Raw material preparation: The raw materials for preparing cemented carbide rods include the following components in parts by weight: 80-94 parts tungsten carbide powder, 0.1-1.8 parts pre-ball-milled cobalt carbonate powder, 6-15 parts cobalt powder, 0.1-0.8 parts chromium carbide powder, and 1-5 parts polyethylene glycol; and the mass ratio of cobalt carbonate to (cobalt + cobalt carbonate) is 1-4.3%.

[0007] S3. Preparation of mixed slurry: The raw materials prepared according to the raw material ratio in S2 are added to the ball milling media and wet ball milled to prepare a mixed slurry.

[0008] S4. Drying: The mixed slurry prepared in S3 is dried to obtain WC-Co-CoCO3-Cr2C3-C mixture, and the mixture is pressed into a cemented carbide billet.

[0009] S5. The billet prepared in S4 is sintered under low pressure and then cooled in the furnace to obtain cemented carbide rods.

[0010] The cemented carbide rods provided by this invention are prepared using tungsten carbide powder, cobalt powder, and chromium carbide powder, with the addition of cobalt carbonate powder. A suitable raw material composition is used, and the ratio of cobalt carbonate to (cobalt + cobalt carbonate) is controlled. The cemented carbide rods are obtained through grinding, drying, billet preparation, and low-pressure sintering. By controlling the process conditions, a pore-free cemented carbide can be obtained. Cobalt carbonate undergoes in-situ decomposition to produce cobalt. The cobalt produced in situ has a high surface energy, which can effectively increase the activation energy of alloy sintering, resulting in cemented carbide rods with higher toughness. The overall reaction formula for the in-situ decomposition of cobalt carbonate to produce cobalt is: CoCO3 + 2C → Co + 3CO↑.

[0011] Furthermore, the raw materials for preparing the cemented carbide rod in S2 include the following components in parts by weight: 88-91 parts of tungsten carbide powder, 0.1-0.5 parts of pre-ball-milled cobalt carbonate powder, 8-10 parts of cobalt powder, 0.5-0.7 parts of chromium carbide powder, and 1-3 parts of polyethylene glycol; and the mass ratio of cobalt carbonate to (cobalt + cobalt carbonate) is 1-4.3%.

[0012] Further, in S1, the milling medium is ethanol, and the mass-to-volume ratio (kg / ml) of the milling medium to the cobalt carbonate is 1:(100-500).

[0013] Preferably, the mass-to-volume ratio (kg / ml) of the ball milling media to the cobalt carbonate is 1:(300-500).

[0014] Preferably, the mass-to-volume ratio (kg / ml) of the ball milling media to the cobalt carbonate is 1:400.

[0015] Furthermore, in S1, the ball-to-material ratio used in the wet ball milling is (5-15):1, and the ball milling time is 45-55 hours;

[0016] Preferably, the ball-to-material ratio used in the wet ball milling is (10-12):1, and the milling time is 49-51 hours.

[0017] Furthermore, in S2, the average particle size of the pre-ball-milled cobalt carbonate is 0.85–0.95 μm.

[0018] Further, in S2, the tungsten carbide powder has an average particle size of 0.7-0.8 μm and a carbon content of 6.0-6.3%; the cobalt powder has an average particle size of 0.8-0.9 μm; and the chromium carbide powder has an average particle size of 0.75-0.85 μm.

[0019] Further, the milling medium is ethanol, and the mass-to-volume ratio (kg / ml) of the milling medium to the cobalt carbonate is 1:(100-500).

[0020] Preferably, the mass-to-volume ratio (kg / ml) of the ball milling media to the cobalt carbonate is 1:(300-500).

[0021] Preferably, the mass-to-volume ratio (kg / ml) of the ball milling media to the cobalt carbonate is 1:400.

[0022] Furthermore, in S3, the ball-to-material ratio used in the wet ball milling is (1-5):1, and the ball milling time is 25-40 hours;

[0023] Preferably, the ball-to-material ratio used in the wet ball milling is (2-4):1, and the milling time is 30-35 hours.

[0024] Furthermore, in S4, drying involves vacuum drying the mixture at 75–85°C.

[0025] Furthermore, the compression molding method in S4 involves adding the mixture into a mold and using a pressure of 150–200 MPa for compression molding.

[0026] Furthermore, in S5, the low-pressure sintering method is as follows: the cemented carbide billet is placed in a low-pressure sintering furnace, first heated to 450-650℃ at a heating rate of 3-7℃ / min and held for 2.5-3.5h, then evacuated to a pressure less than 5Pa, then heated to 1240-1260℃ at a heating rate of 8-12℃ / min and held for 1-2h, then heated to 1400-1420℃ at a heating rate of 3-7℃ / min and held for 0.5-1.5h, and under the condition of maintaining a constant temperature, Ar gas is introduced until the pressure reaches 8-12MPa and held for 0.5-1.5h.

[0027] This application employs the aforementioned low-pressure sintering process. First, by rapidly heating to 450–650°C and holding at that temperature, the forming agent is decomposed into a gaseous state and discharged, while cobalt carbonate decomposes into cobalt oxide. Then, the temperature is raised to 1240–1260°C and held, which promotes solid-phase diffusion between powder particles. Simultaneously, the cobalt oxide undergoes a carbothermic reaction to generate ultrafine Co in situ. The temperature is then raised to 1400–1420°C for liquid-phase sintering. Finally, under pressure, residual porosity is eliminated, and the alloy densification is enhanced.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. This invention proposes a novel method to promote low-carbon metallurgy of cemented carbide by adding a small amount of CoCO3 powder during the preparation process. Then, a pore-free cemented carbide is obtained by low-pressure sintering. After ball milling, cobalt carbonate particles can be produced. The cobalt generated in situ has a high surface energy, which can effectively improve the activation energy of alloy sintering. The prepared cemented carbide rod has higher toughness and excellent comprehensive performance.

[0030] 2. This invention provides a method for directly preparing cemented carbide rods by adding a small amount of pre-ball-milled CoCO3. This method adds a small amount of CoCO3 during the ball milling stage, and combined with an optimized cemented carbide rod preparation process, it can reduce costs and improve the performance of cemented carbide. This method is beneficial for reducing production costs, reducing energy consumption in the entire cemented carbide production process, and is conducive to large-scale industrial use. Attached Figure Description

[0031] Figure 1 Micrograph of the cemented carbide rod sample prepared in Example 1;

[0032] Figure 2 Micrograph of the cemented carbide rod sample prepared in Example 2;

[0033] Figure 3 Micrograph of the cemented carbide rod sample prepared in Example 3;

[0034] Figure 4 Micrograph of the cemented carbide rod sample prepared for Comparative Example 1;

[0035] Figure 5 Micrograph of the cemented carbide rod sample prepared for Comparative Example 2;

[0036] Figure 6 Micrograph of the cemented carbide rod sample prepared for Comparative Example 3. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Unless otherwise specified, all methods described herein are conventional methods, and all raw materials described herein are available from publicly available commercial sources.

[0039] Example 1

[0040] (1) Pre-ball milling of cobalt carbonate: After mixing cobalt carbonate raw material with anhydrous ethanol, wet ball milling is performed, followed by sieving and vacuum drying at 80℃ for later use. The relevant ball milling process and parameters are shown in Table 1 below:

[0041] Table 1

[0042]

[0043] (2) Raw material preparation: The raw materials for preparing cemented carbide rods shall be prepared according to the following mass percentages. The raw material composition of the mixture is shown in Table 2 below:

[0044] Table 2

[0045]

[0046] In Table 2, the average particle size of the WC powder used was 0.76 µm, and the carbon content was 6.15%; the average particle size of the CoCO3 powder was 0.91 µm; the average particle size of the Co powder was 0.85 µm; the average particle size of the Cr3C2 powder was 0.82 µm, and the mass ratio of CoCO3 / (Co+CoCO3) was 1.56%.

[0047] (3) Preparation of mixed slurry: According to the above raw materials, anhydrous ethanol is added and wet ball milling is performed to obtain mixed slurry. The ball milling process and parameters are shown in Table 3 below:

[0048] Table 3

[0049]

[0050] (4) Drying and molding: The mixed slurry is vacuum dried at 80°C to obtain WC-Co-CoCO3-Cr3C2 mixture, which is then molded into bar blanks by pressing at 180MPa.

[0051] (5) Low-pressure sintering: The cemented carbide rod blanks obtained by molding are subjected to low-pressure sintering. The method of low-pressure sintering is as follows: First, the temperature is raised to 550℃ at a heating rate of 5℃ / min and held for 3 hours. Vacuum is then drawn. When the pressure inside the furnace is less than 5Pa, the temperature is raised to 1250℃ at a rate of 10℃ / min and held for 1.5 hours. Then, the temperature is raised to 1420℃ at a rate of 5℃ / min and held for 1 hour. Then, Ar gas is introduced to 10MPa and held for 1 hour while maintaining the sintering temperature of 1420℃. After completing the low-pressure sintering treatment, the furnace is cooled. After being taken out of the furnace, cemented carbide rods are obtained. The porosity of the sample is A02B00C00. The microstructure of the obtained cemented carbide rods is shown in the figure. Figure 1 As shown in Table 4, the physical properties of the obtained cemented carbide rods are as follows:

[0052] Table 4

[0053]

[0054] Example 2

[0055] (1) Pre-ball milling of cobalt carbonate: After mixing cobalt carbonate raw material with anhydrous ethanol, wet ball milling is performed, followed by sieving and vacuum drying at 80℃ for later use. The relevant ball milling process and parameters are shown in Table 5 below:

[0056] Table 5

[0057]

[0058] (2) Raw material preparation: The raw materials for preparing cemented carbide rods shall be prepared according to the following mass percentages. The raw material composition of the mixture is shown in Table 6 below:

[0059] Table 6

[0060]

[0061] In Table 6, the average particle size of the WC powder used was 0.76 µm, and the carbon content was 6.15%; the average particle size of the CoCO3 powder was 0.91 µm; the average particle size of the Co powder was 0.85 µm; and the average particle size of the Cr3C2 powder was 0.82 µm. The mass ratio of CoCO3 to (Co+CoCO3) was 4.17%.

[0062] (3) Preparation of mixed slurry: According to the above raw materials, anhydrous ethanol is added and wet ball milling is performed to obtain mixed slurry. The ball milling process and parameters are shown in Table 7 below:

[0063] Table 7

[0064]

[0065] (4) Drying and molding: The mixed slurry is vacuum dried at 80°C to obtain WC-Co-CoCO3-Cr3C2 mixture, which is then molded into bar blanks by pressing at 180MPa.

[0066] (5) Low-pressure sintering: The cemented carbide rod blank obtained by molding is placed in a low-pressure sintering furnace. First, the temperature is raised to 550℃ at a heating rate of 5℃ / min and held for 3 hours. Then, a vacuum is drawn. When the pressure inside the furnace is less than 5Pa, the temperature is raised to 1250℃ at a rate of 10℃ / min and held for 1.5 hours. Then, the temperature is raised to 1420℃ at a rate of 5℃ / min and held for 1 hour. Then, Ar gas is introduced to 10MPa while maintaining the sintering temperature of 1420℃ and held for 1 hour. After the low-pressure sintering treatment is completed, the furnace is cooled. After being taken out of the furnace, cemented carbide rods are obtained. The porosity of the sample is A02B00C00. The microstructure of the obtained cemented carbide rods is shown in the figure. Figure 1As shown in Table 8, the physical properties of the obtained cemented carbide rods are as follows:

[0067] Table 8

[0068]

[0069] Example 3

[0070] (1) Pre-ball milling of cobalt carbonate: After mixing cobalt carbonate raw material with anhydrous ethanol, wet ball milling is performed, followed by sieving and vacuum drying at 80℃ for later use. The relevant ball milling process and parameters are shown in Table 9 below:

[0071] Table 9

[0072]

[0073] (2) Raw material preparation: The raw materials for preparing cemented carbide rods shall be prepared according to the following mass percentages. The raw material composition of the mixture is shown in Table 10 below:

[0074] Table 10

[0075]

[0076] The WC powder used had an average particle size of 0.76 µm and a carbon content of 6.15%; the CoCO3 powder had an average particle size of 0.91 µm; the Co powder had an average particle size of 0.85 µm; and the Cr3C2 powder had an average particle size of 0.82 µm. The mass ratio of CoCO3 to (Co + CoCO3) was 3.27%.

[0077] (3) Preparation of mixed slurry: According to the above raw materials, add anhydrous ethanol and perform wet ball milling to obtain mixed slurry. The ball milling process and parameters are shown in Table 11 below:

[0078] Table 11

[0079]

[0080] (4) Drying and molding: The mixed slurry is vacuum dried at 80°C to obtain WC-Co-CoCO3-Cr3C2 mixture, which is then molded into bar blanks by pressing at 180MPa.

[0081] (5) Low-pressure sintering: The cemented carbide rod blank obtained by molding is placed in a low-pressure sintering furnace. First, the temperature is raised to 550℃ at a heating rate of 5℃ / min and held for 3 hours. Then, a vacuum is drawn. When the pressure inside the furnace is less than 5Pa, the temperature is raised to 1250℃ at a rate of 10℃ / min and held for 1.5 hours. Then, the temperature is raised to 1420℃ at a rate of 5℃ / min and held for 1 hour. Then, Ar gas is introduced to 10MPa while maintaining the sintering temperature of 1420℃ and held for 1 hour. After the low-pressure sintering treatment is completed, the furnace is cooled. After being taken out of the furnace, cemented carbide rods are obtained. The porosity of the sample is A02B00C00. The microstructure of the obtained cemented carbide rods is shown in the figure. Figure 1 As shown in Table 12, the physical properties of the obtained cemented carbide rods are as follows:

[0082] Table 12

[0083]

[0084] Comparative Example 1

[0085] (1) Pre-ball milling of cobalt carbonate: After mixing cobalt carbonate raw material with anhydrous ethanol, wet ball milling is performed, followed by sieving and vacuum drying at 80℃ for later use. The relevant ball milling process and parameters are shown in Table 13 below:

[0086] Table 13

[0087]

[0088] (2) Raw material preparation: The raw materials for preparing cemented carbide rods shall be prepared according to the following mass percentages. The raw material composition of the mixture is shown in Table 14 below:

[0089] Table 14

[0090]

[0091] The WC powder used had an average particle size of 0.76 µm and a carbon content of 6.15%; the CoCO3 powder had an average particle size of 0.91 µm; the Co powder had an average particle size of 0.85 µm; and the Cr3C2 powder had an average particle size of 0.82 µm. The mass ratio of CoCO3 to (Co + CoCO3) was 7.14%.

[0092] (3) Preparation of mixed slurry: According to the above raw materials, add anhydrous ethanol and perform wet ball milling to obtain mixed slurry. The ball milling process and parameters are shown in Table 15 below:

[0093] Table 15

[0094]

[0095] (4) Drying and molding: The mixed slurry is vacuum dried at 80°C to obtain WC-Co-CoCO3-Cr3C2 mixture, which is then molded into bar blanks by pressing at 180MPa.

[0096] (5) Low-pressure sintering: The cemented carbide rod blank obtained by molding is placed in a low-pressure sintering furnace. First, the temperature is raised to 550℃ at a heating rate of 5℃ / min and held for 3 hours. Then, a vacuum is drawn. When the pressure inside the furnace is less than 5Pa, the temperature is raised to 1250℃ at a rate of 10℃ / min and held for 1.5 hours. Then, the temperature is raised to 1420℃ at a rate of 5℃ / min and held for 1 hour. Then, Ar gas is introduced to 10MPa while maintaining the sintering temperature of 1420℃ and held for 1 hour. After completing the low-pressure sintering treatment, the furnace is cooled. After being taken out of the furnace, cemented carbide rods are obtained. The porosity of the sample is A04B02C00. The microstructure of the obtained cemented carbide rods is shown in the figure. Figure 4 As shown in Table 16, the physical properties of the obtained cemented carbide rods are as follows:

[0097] Table 16

[0098]

[0099] Comparative Example 2

[0100] (1) Pre-ball milling of cobalt carbonate: After mixing cobalt carbonate raw material with anhydrous ethanol, wet ball milling is performed, followed by sieving and vacuum drying at 80°C for later use. The relevant ball milling process and parameters are shown in Table 17 below:

[0101] Table 17

[0102]

[0103] (2) Raw material preparation: The raw materials for preparing cemented carbide rods shall be prepared according to the following mass percentages. The raw material composition of the mixture is shown in Table 18 below:

[0104] Table 18

[0105]

[0106] The WC powder used had an average particle size of 0.76 µm and a carbon content of 6.15%; the CoCO3 powder had an average particle size of 0.91 µm; the Co powder had an average particle size of 0.85 µm; and the Cr3C2 powder had an average particle size of 0.82 µm. The mass ratio of CoCO3 to (Co + CoCO3) was 13.63%.

[0107] (3) Preparation of mixed slurry: According to the above raw materials, add anhydrous ethanol and perform wet ball milling to obtain mixed slurry. The ball milling process and parameters are shown in Table 19 below:

[0108] Table 19

[0109]

[0110] (4) Drying and molding: The mixed slurry is vacuum dried at 80°C to obtain WC-Co-CoCO3-Cr3C2 mixture, which is then molded into bar blanks by pressing at 180MPa.

[0111] (5) Low-pressure sintering: The cemented carbide rod blank obtained by molding is placed in a low-pressure sintering furnace. First, the temperature is raised to 550℃ at a heating rate of 5℃ / min and held for 3 hours. Then, a vacuum is drawn. When the pressure inside the furnace is less than 5Pa, the temperature is raised to 1250℃ at a rate of 10℃ / min and held for 1.5 hours. Then, the temperature is raised to 1420℃ at a rate of 5℃ / min and held for 1 hour. Then, Ar gas is introduced to 10MPa while maintaining the sintering temperature of 1420℃ and held for 1 hour. After completing the low-pressure sintering treatment, the furnace is cooled. After being taken out of the furnace, cemented carbide rods are obtained. The porosity of the sample is A06B04C00. The microstructure of the obtained cemented carbide rods is shown in the figure. Figure 1 As shown in Table 20, the physical properties of the obtained cemented carbide rods are as follows:

[0112] Table 20

[0113]

[0114] Comparative Example 3

[0115] (1) Preparation of raw materials: The raw materials for preparing cemented carbide rods shall be prepared according to the following mass percentages. The raw material composition of the mixture is shown in Table 21 below:

[0116] Table 21

[0117]

[0118] In Table 21, the WC powder used has an average particle size of 0.76 µm and a carbon content of 6.15%; the Co powder has an average particle size of 0.85 µm; and the Cr3C2 powder has an average particle size of 0.82 µm.

[0119] (3) Preparation of mixed slurry: According to the above raw materials, anhydrous ethanol is added and wet ball milling is performed to obtain mixed slurry. The ball milling process and parameters are shown in Table 22 below:

[0120] Table 22

[0121]

[0122] (4) Drying and molding: The mixed slurry is vacuum dried at 80°C to obtain WC-Co-Cr3C2 mixture, which is then molded into bar blanks by pressing at 180MPa.

[0123] (5) Low-pressure sintering: The cemented carbide rod blank obtained by molding is placed in a low-pressure sintering furnace. First, the temperature is raised to 550℃ at a heating rate of 5℃ / min and held for 3 hours. Then, a vacuum is drawn. When the pressure inside the furnace is less than 5Pa, the temperature is raised to 1250℃ at a rate of 10℃ / min and held for 1.5 hours. Then, the temperature is raised to 1420℃ at a rate of 5℃ / min and held for 1 hour. Then, Ar gas is introduced to 10MPa while maintaining the sintering temperature of 1420℃ and held for 1 hour. After the low-pressure sintering treatment is completed, the furnace is cooled. After being taken out of the furnace, cemented carbide rods are obtained. The porosity of the sample is A02B00C00. The microstructure of the obtained cemented carbide rods is shown in the figure. Figure 6 As shown in Table 23, the physical properties of the obtained cemented carbide rods are as follows:

[0124] Table 23

[0125]

[0126] As can be seen from Examples 1-3 and Comparative Examples 1-2, the embodiments of this application, by adding a portion of cobalt carbonate to the mixture to replace cobalt and controlling the mass ratio of CoCO3 / (Co+CoCO3) to be 1-4.3%, and then molding and low-pressure sintering the prepared mixture, produce a cemented carbide with no pores, high density, and significantly improved bending strength. Comparative Examples 1-2, with their higher amounts of added cobalt carbonate, produced cemented carbide rods with obvious pores, indicating that strict control of the CoCO3 / (Co+CoCO3) ratio is necessary in preparing the cemented carbide materials described in the embodiments of this application.

[0127] Based on Examples 1-3 and Comparative Example 3, it can be seen that Comparative Example 3 did not use cobalt carbonate, and the prepared cemented carbide was free of pores and had high density. Examples 1-3 used cobalt carbonate, which was cheaper, to replace part of the cobalt, and the fracture toughness of the prepared cemented carbide rods was improved compared with Comparative Example 3, and the overall performance was better than that of Comparative Example 3.

[0128] The above-mentioned test methods for cemented carbide properties are as follows: metallographic and microstructure analysis are conducted in accordance with the provisions of GB / T 3488.1-2014; Rockwell hardness is conducted in accordance with the provisions of GB / T 3849.1-2015; density is conducted in accordance with GB / T 3850-2015; coercivity is conducted in accordance with the provisions of GB / T 3848-2017; fracture toughness is conducted in accordance with the provisions of GB / T 33819-2017; and bending strength is conducted in accordance with the provisions of GB / T 3851-2015.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them; although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this application or equivalent substitutions can be made to some technical features, all of which should be covered within the scope of the technical solutions claimed in this application.

Claims

1. A method for preparing cemented carbide rods by adding cobalt carbonate, characterized in that, Includes the following steps: S1. Cobalt carbonate pre-ball milling: After mixing cobalt carbonate raw material with ball milling media, wet ball milling is performed, followed by sieving and drying for later use; S2. Raw material preparation: The raw materials for preparing cemented carbide rods include the following components in parts by weight: 80-94 parts tungsten carbide powder, 0.1-1.8 parts pre-ball-milled cobalt carbonate powder, 6-15 parts cobalt powder, 0.1-0.8 parts chromium carbide powder, and 1-5 parts polyethylene glycol; and the mass ratio of cobalt carbonate to (cobalt + cobalt carbonate) is 1-4.3%. S3. Preparation of mixed slurry: The raw materials prepared according to the raw material ratio in S2 are added to the ball milling media and wet ball milled to prepare a mixed slurry. S4. Drying: The mixed slurry prepared in S3 is dried to obtain WC-Co-CoCO3-Cr2C3-C mixture, and the mixture is pressed into a cemented carbide billet. S5. The billet prepared in S4 is sintered under low pressure and then cooled in the furnace to obtain cemented carbide rods.

2. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1, characterized in that, In S1, the ball milling medium is ethanol, and the mass-to-volume ratio of the ball milling medium to the cobalt carbonate is 1:(100-500), with the unit of mass-to-volume ratio being kg / ml.

3. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 2, characterized in that, In S1, the mass-to-volume ratio of the ball milling media to the cobalt carbonate is 1:(300-500), and the unit of the mass-to-volume ratio is kg / ml.

4. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 2, characterized in that, In S1, the mass-to-volume ratio of the ball milling media to the cobalt carbonate is 1:400, and the unit of the mass-to-volume ratio is kg / ml.

5. A method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1 or 2, characterized in that, In S1, the ball-to-material ratio used in the wet ball milling is (5-15):1, and the ball milling time is 45-55 hours.

6. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 5, characterized in that, In S1, the ball-to-material ratio used in the wet ball milling is (10-12):1, and the milling time is 49-51 hours.

7. A method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1 or 2, characterized in that, In S2, the average particle size of the pre-ball-milled cobalt carbonate powder is 0.85–0.95 μm.

8. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1, characterized in that, In S2, the tungsten carbide powder has an average particle size of 0.7–0.8 μm and a carbon content of 6.0–6.3%; the cobalt powder has an average particle size of 0.8–0.9 μm; and the chromium carbide powder has an average particle size of 0.75–0.85 μm.

9. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1, characterized in that, In S3, the milling medium is ethanol, and the mass-to-volume ratio of the milling medium to the cobalt carbonate is 1:(100-500), with the unit of mass-to-volume ratio being kg / ml.

10. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 9, characterized in that, In S3, the mass-to-volume ratio of the ball milling media to the cobalt carbonate is 1:(300-500), and the unit of the mass-to-volume ratio is kg / ml.

11. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 9, characterized in that, In S3, the mass-to-volume ratio of the ball milling media to the cobalt carbonate is 1:400, and the unit of the mass-to-volume ratio is kg / ml.

12. In the method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1, in S3, the ball-to-material ratio used in the wet ball milling is (1-5):1, and the ball milling time is 25-40h.

13. In the method for preparing cemented carbide rods by adding cobalt carbonate according to claim 12, in S3, the ball-to-material ratio used in the wet ball milling is (2-4):1, and the ball milling time is 30-35h.

14. In the method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1, in step S4, drying is performed by vacuum drying the mixture at 75-85°C.

15. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1, wherein in S4, the molding method is to add the mixture into a mold and mold it under a pressure of 150-200 MPa.

16. The method for preparing cemented carbide rods by adding cobalt carbonate according to claim 1, wherein in S5, the low-pressure sintering method is as follows: the cemented carbide billet is placed in a low-pressure sintering furnace, first heated to 450-650℃ at a heating rate of 3-7℃ / min and held for 2.5-3.5h, then evacuated to a pressure less than 5Pa, then heated to 1240-1260℃ at a heating rate of 8-12℃ / min and held for 1-2h, then heated to 1400-1420℃ at a heating rate of 3-7℃ / min and held for 0.5-1.5h, and under the condition of maintaining a constant temperature, Ar gas is introduced until the pressure reaches 8-12MPa and held for 0.5-1.5h.

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