CN101285134A - A kind of preparation method of WC-Co cemented carbide - Google Patents

Abstract

The invention provides a preparation method of WC-Co cemented carbide, which adopts a method of carbonization and sintering integration, and the steps are (1) using a dielectric barrier discharge plasma-assisted high-energy ball mill to process W , C, Co raw materials and carbon replenishment are ball milled to obtain W, C, Co mixed powder; (2) press the W, C, Co mixed powder to obtain a green body; (3) put the green body into WC-Co cemented carbide was prepared by sintering in a heat source environment. The raw materials of W, C and Co are proportioned according to WC-XCo, and the value range of X is 3≤X≤20. The invention can shorten the production cycle of the cemented carbide preparation process, simplify the process, reduce energy consumption and reduce the chance of introducing impurities.

Description

A kind of preparation method of WC-Co cemented carbide

technical field

The invention relates to the field of WC-Co hard alloy, in particular to a preparation method of WC-Co hard alloy.

Background technique

WC-Co cemented carbide is the earliest developed cemented carbide and is currently the most widely used cemented carbide. The traditional WC-Co cemented carbide preparation process includes the following steps: first carbonize tungsten powder to prepare tungsten carbide; then mix tungsten carbide and cobalt powder and then wet grind; then add forming agent to the slurry obtained by wet grinding; Then it is dried and granulated; then it is pressed into shape; finally it is loaded into a furnace for degreasing and sintering. These steps are relatively complicated, which often bring disadvantages such as long production cycle, cumbersome process, increased chance of introducing impurities, and high energy consumption. With the attention paid to energy consumption and efficiency in modern society, it is of great value to develop new high-efficiency and low-energy consumption WC-Co cemented carbide production processes.

In recent years, plasma technology has been widely used in aerospace, chemical industry, machinery, materials, electronics and many other fields. Dielectric barrier discharge plasma is a kind of plasma technology. Dielectric barrier discharge plasma can occur under normal pressure. It has extremely high electron density and electron energy. This is not only because it is a pure heat source, but also because it It has a large number of high-energy particles produced by strong ionization effects and becomes an activation source. The introduction of dielectric barrier discharge in ball milling can not only refine the powder, but also improve the activity of the powder. Therefore, it is expected to simplify the production process of cemented carbide by using the composite powder processed by dielectric barrier discharge plasma assisted ball milling as raw material.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings and deficiencies of the above-mentioned prior art, and provide a method for preparing WC-Co cemented carbide, which adopts a carbonization and sintering integration method, which can improve the long production cycle in the cemented carbide preparation process , The process is cumbersome, the energy consumption is high, and the chance of introducing impurities is increased due to the cumbersome process.

The purpose of the present invention is achieved through the following technical solutions: a preparation method of WC-Co cemented carbide, which adopts the method of carbonization and sintering integration, specifically comprising the following steps:

(1) Using a dielectric barrier discharge plasma-assisted high-energy ball mill to mill W, C, Co raw materials and carbon supplements by using a dielectric barrier discharge plasma-assisted high-energy ball mill to obtain W, C, and Co mixed powder;

(2) Compressing the mixed powder of W, C and Co to obtain a green body;

(3) Putting the green body into a heat source environment and sintering to prepare WC-Co cemented carbide.

In order to better realize the present invention, the W, C, and Co raw materials described in step (1) are proportioned according to WC-XCo, wherein the value range of X is 3≤X≤20, and the carbon supplement and the C raw material The mass ratio is 4% to 10%.

The dielectric barrier discharge plasma-assisted high-energy ball mill includes a base, a grinding ball, a spring, a motor, an elastic coupling, an exciting block, a frame, a ball mill tank, a vacuum valve, a front cover plate, a cemented carbide tank lining, The outer tank of the ball mill tank, the rear cover plate, the electrode rod and the plasma power supply. The ball mill tank is installed on the frame, and the inside of the ball mill tank is placed with grinding balls. The vibrating block and the driving motor are installed on the base, and are respectively connected to the frame and the exciting block through elastic joints. The plasma power supply is connected to any bolt and electrode rod of the front cover respectively. The inner lining of the cemented alloy tank is WC-XCo cemented carbide, and the value range of X is correspondingly 3≤X≤20.

The dielectric barrier discharge plasma-assisted high-energy ball milling method described in step (1) comprises the following steps:

(1.1) Install the front cover and electrode rod of the ball mill, and connect the front cover and electrode rod to the positive and negative stages of the plasma power supply respectively, wherein the electrode rod is connected to the positive pole of the plasma power supply, and the front cover is connected to The negative pole of the plasma power supply;

(1.2) Put grinding balls and W, C, Co raw materials and carbon supplement in the ball milling tank, after the electrode rod and grinding balls are all in contact with W, C, Co raw materials, cover the rear cover of the ball milling tank;

(1.3) Vacuumize the airtight ball milling tank through the vacuum valve, and then pass the discharge gas medium through the vacuum valve until the pressure in the ball milling tank is 0.01 to 0.30 MPa;

(1.4) Turn on the plasma power supply, adjust the discharge parameters according to the discharge gas medium and its pressure, the plasma power supply voltage is 3-30KV, the discharge frequency corresponds to the power supply voltage, realize dielectric barrier discharge, and start the drive motor to drive the vibration block , so that the frame and the ball mill jar fixed on the frame vibrate at the same time, thereby changing the relative position of the electrode rod and the ball in the ball mill jar, and performing dielectric barrier discharge plasma-assisted high-energy ball milling.

In the dielectric barrier discharge plasma-assisted high-energy ball milling method described above, the total volume of the balls accounts for 70-75% of the volume of the ball mill tank, wherein balls with a diameter of 20-22mm account for 10-15% of the total number of balls, and balls with a diameter of 15-18mm The grinding balls account for 75-80% of the total grinding balls, and the grinding balls with a diameter of 10mm account for 10% of the total grinding balls; the loose volume of the W, C, and Co powders accounts for 30%-130% of the gaps between the grinding balls.

The ball-to-powder ratio of ball milling is 10:1-200:1.

The discharge gas medium is argon, nitrogen, ammonia or methane.

The excitation block adopts a double amplitude of 5 mm to 10 mm, a motor speed of 930 to 1400 r/min, and a ball milling time of 1 to 9 hours.

The press forming method described in step (2) is press forming, and the unit press force is 50MPa˜1000MPa.

The temperature of the heat source environment described in step (3) is 1320-1480°C; the atmosphere environment of the heat source environment is vacuum, argon or nitrogen, and the atmosphere pressure is 1Pa-10MPa; the sintering method is vacuum sintering or vacuum sintering combined with hot pressing Sintering (vacuum sintering for pressure less than 0.1MPa).

Compared with the traditional technology, the present invention has the following advantages and characteristics:

(1) The implementation process is simple, the production cycle is short, and the chance of introducing impurities is small. The technology of directly pressing the ball-milled powder into a green body replaces the process of adding forming agents to granulate, dry, and press into a green body in the traditional process. This technology greatly simplifies the preparation process of cemented carbide and shortens the production cycle. , reducing the chance of impurity introduction in the traditional process.

(2) Low energy consumption. The technology of carbonizing and sintering the integrated technology of directly pressing the mixed powder of W, C and Co to replace the technology of first carbonizing W powder in the traditional process, and then making the mixed powder of WC and Co to make the green body sintered and formed. The present invention only has one heating process from room temperature to high temperature, while the traditional technology needs to undergo one heating process from room temperature to high temperature during W powder carbonization and green body sintering, thus greatly reducing energy consumption.

Description of drawings

Fig. 1 is the structural representation of the dielectric barrier discharge plasma-assisted high-energy ball mill that the present invention adopts;

Fig. 2 is a cross-sectional view of the dielectric barrier discharge plasma-assisted high-energy ball mill shown in Fig. 1;

Fig. 3 is the process flow sheet of the preparation method of WC-Co cemented carbide of the present invention;

Fig. 4 is the XRD spectrogram of the WC-Co (taking X=10, vacuum sintering as example) cemented carbide prepared by the preparation method of WC-Co cemented carbide of the present invention;

Fig. 5 is the SEM image of the WC-Co (taking X=10, vacuum sintering as an example) cemented carbide prepared by the preparation method of the WC-Co cemented carbide of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto.

Example 1

WC-10Co cemented carbide is prepared by the preparation method of this WC-Co cemented carbide, as shown in Figures 1 and 2, a dielectric barrier discharge plasma-assisted high-energy ball mill is used, which includes a base 1, a grinding ball 2, a spring 3, and a motor 4. Elastic coupling 5, excitation block 6, frame 7, ball mill tank 8, vacuum valve 8-1, front cover plate 8-2, hard alloy tank lining 8-3, ball mill tank outer tank 8- 4. Rear cover plate 8-5, electrode rod 9, plasma power supply 10. The ball mill pot 8 is installed on the frame 7, and the grinding ball 2 is placed inside it. The frame 7 is installed on the base 1 through the spring 3, and an exciting block 6 is arranged on the outside thereof, and the drive motor 4 is installed on the base 1, and through The elastic coupling 5 is connected with the frame 7 and the vibration-exciting block 6 respectively. The plasma power source 10 is connected to any one of the bolts 8-6 and the electrode rod 9 of the front cover plate 8-2 respectively.

In the ball milling tank 8, stainless steel is selected as the matrix material as the outer tank 8-4 of the ball milling tank, and the hard alloy tank lining 8-3 is WC-10Co hard alloy.

As shown in Figure 3, the preparation method of WC-Co cemented carbide is used to prepare WC-10Co cemented carbide, which adopts the method of carbonization and sintering integration, which specifically includes the following steps:

(1) Carry out ball milling to W, C, Co raw material and supplementary carbon by plasma-assisted high-energy ball mill adopting dielectric barrier discharge plasma-assisted high-energy ball milling method, obtain W, C, Co mixed powder, wherein, described W, C, Co Each raw material is proportioned according to WC-10Co, and the mass ratio of the carbon supplement to the C raw material is 7.5%;

Wherein, as shown in Figures 1 and 2, the steps of the dielectric barrier discharge plasma-assisted high-energy ball milling method are:

(1.1) Install the front cover and electrode rod of the ball mill, and connect the front cover and electrode rod to the positive and negative stages of the plasma power supply respectively, wherein the electrode rod is connected to the positive pole of the plasma power supply, and the front cover is connected to The negative pole of the plasma power supply;

(1.2) Put grinding balls and W, C, Co raw materials and carbon supplement in the ball milling tank, after the electrode rod and grinding balls are all in contact with W, C, Co raw materials, cover the rear cover of the ball milling tank;

(1.3) Vacuumize the airtight ball milling jar through a vacuum valve, then feed the discharge gas medium through the vacuum valve until the pressure in the ball milling jar is 0.12MPa;

(1.4) Turn on the plasma power supply, adjust the discharge parameters according to the discharge gas medium and its pressure, the plasma power supply voltage is 28KV, the discharge frequency corresponds to the power supply voltage, which is 60KHz, realizes dielectric barrier discharge, and starts the drive motor to drive the excitation block, so that the frame and the ball mill pot fixed on the frame vibrate at the same time, thereby changing the relative position of the electrode rod and the ball in the ball mill pot, and performing dielectric barrier discharge plasma-assisted high-energy ball milling.

In the dielectric barrier discharge plasma-assisted high-energy ball milling method described above, the total volume of the balls accounts for 70-75% of the volume of the ball mill tank, wherein balls with a diameter of 20-22mm account for 10-15% of the total number of balls, and balls with a diameter of 15-18mm The grinding balls account for 75-80% of the total grinding balls, and the grinding balls with a diameter of 10mm account for 10% of the total grinding balls; the loose volume of the W, C, and Co powders accounts for 30%-130% of the gaps between the grinding balls; The ball-to-powder ratio is 80:1; the discharge gas medium is argon, nitrogen, ammonia or methane; the excitation block adopts a double amplitude of 5 mm to 10 mm, and the motor speed is 930 to 1400 r/min; the ball milling time is 3 hours.

(2) The W, C, and Co mixed powders are put into a mould, pressed into a mold, the unit pressure is 250MPa, the holding time is 3min, and then the mold is demoulded to obtain a green body;

(3) Putting the green body into a heat source environment and sintering to prepare WC-Co cemented carbide.

(3) Using the method of vacuum sintering combined with hot-pressing sintering, the green body prepared in step (2) was heated to 1340°C at a rate of 10°C/min under the condition of 1Pa and kept for 15min, and then heated at a rate of 2.5bar/min Fill it with argon gas at a speed of 5MPa, keep it warm for 35 minutes, and then cool it to room temperature to prepare WC-10Co cemented carbide.

The prepared WC-10Co cemented carbide has a Rockwell hardness HRA of 90.2 and a flexural strength (TRS) of 3471MPa.

Example 2

The WC-10Co cemented carbide was prepared by the preparation method of this WC-Co cemented carbide, and its step (1) was basically the same as that of Example 1, except that the ball-to-powder ratio was 16:1, and the ball milling time was 6h;

Step (2) is identical with embodiment 1;

Step (3): Using the method of vacuum sintering, the green body prepared in step (2) was heated to 1380°C at a rate of 10°C/min under the condition of 1Pa and kept for 60min, and then cooled to room temperature to obtain WC- 10Co cemented carbide.

The prepared WC-10Co cemented carbide has a Rockwell hardness HRA of 90.4 and a flexural strength (TRS) of 2305MPa. Its XRD spectrum is shown in Figure 4, and its SEM picture is shown in Figure 5.

Example 3

The WC-10Co hard alloy is prepared by the preparation method of this WC-Co hard alloy, and the steps (1) and (2) are exactly the same as in Example 1; the step (3) is exactly the same as in Example 2.

The prepared WC-10Co cemented carbide has a Rockwell hardness HRA of 90.1 and a flexural strength (TRS) of 1520MPa.

Example 4

The WC-3Co hard alloy is prepared by the preparation method of this WC-Co hard alloy, and the step (1) is basically the same as that of Example 1, except that the inner lining of the hard alloy tank is WC-3Co hard alloy. Alloy; W, C, and Co are proportioned according to WC-3Co, and 4% carbon is added; the ball powder ratio is 100:1, and the ball milling time is 9h; the plasma power supply voltage is 30KV, and the pressure inside the ball mill tank is 0.01MPa;

Step (2): Put the ball-milled powder into a mold, press to form, the unit pressure is 1000MPa, the holding time is 2min, and then the mold is demoulded to obtain a green body;

Step (3): Using the method of vacuum sintering, the green body prepared in step (2) is heated to 1480°C at a rate of 10°C/min under the condition of 0.02Mpa argon gas and kept for 60min, then cooled to room temperature to produce Get WC-3Co cemented carbide.

Example 5

The WC-6Co hard alloy is prepared by the preparation method of this WC-Co hard alloy, and the step (1) is basically the same as that of Example 1, except that the inner lining of the hard alloy tank is WC-6Co hard alloy. Alloy; W, C, and Co are proportioned according to WC-6Co, and 6% carbon is added; the ball powder ratio is 150:1, and the ball milling time is 2h; the plasma power supply voltage is 22KV, and the pressure inside the ball mill tank is 0.18MPa;

Step (2): Put the ball-milled powder into a mold, press to form, the unit pressure is 750MPa, the holding time is 90s, and then demoulding to obtain a green body;

Step (3): Using the method of vacuum sintering combined with hot pressing sintering, heat the green body prepared in step (2) to 1440°C at a rate of 10°C/min under the condition of 1Pa and keep it warm for 15min, and then heat it at 3bar/min The speed is filled with nitrogen to 8MPa, and the heat preservation is continued for 45min, and then cooled to room temperature to obtain WC-6Co cemented carbide.

Example 6

WC-13Co hard alloy is prepared by adopting the preparation method of this WC-Co hard alloy. Alloy; W, C, and Co are formulated according to WC-13Co, and 8% carbon is added; the ball powder ratio is 200:1, and the ball milling time is 1h; the plasma power supply voltage is 3KV, and the pressure inside the ball mill tank is 0.30MPa;

Step (2): Put the ball-milled powder into a mold, press to form, the unit pressure is 500MPa, the holding time is 2min, and then the mold is demoulded to obtain a green body;

Step (3): Using the method of vacuum sintering combined with hot-pressing sintering, heat the green body prepared in step (2) to 1400°C at a rate of 10°C/min under the condition of 1Pa and keep it warm for 15min, and then heat it at 5bar/min The speed is filled with argon to 10MPa, and the heat preservation is continued for 45 minutes, and then cooled to room temperature to obtain WC-13Co cemented carbide.

Example 7

The WC-17Co hard alloy is prepared by the preparation method of this WC-Co hard alloy, and the step (1) is basically the same as that of Example 1, except that the inner lining of the hard alloy tank is WC-17Co hard alloy. Alloy; W, C, and Co are proportioned according to WC-17Co, and 9.5% carbon is added; the ball powder ratio is 50:1, and the ball milling time is 4.5h; the plasma power supply voltage is 8KV, and the pressure inside the ball mill tank is 0.28MPa;

Step (2): Put the ball-milled powder into a mold, press to form, the unit pressure is 100MPa, the holding time is 150s, and then demolded to obtain a green body;

Step (3): Using the method of vacuum sintering, the green body prepared in step (2) was heated to 1320°C at a rate of 10°C/min under the condition of 1Pa and kept for 90min, then cooled to room temperature to obtain WC- 17Co cemented carbide.

Example 8

WC-20Co hard alloy is prepared by adopting the preparation method of this WC-Co hard alloy. Alloy; W, C, and Co are formulated according to WC-20Co, and 10% carbon is added; the ball powder ratio is 10:1, and the ball milling time is 7h; the plasma power supply voltage is 15KV, and the pressure inside the ball mill tank is 0.25MPa;

Step (2): Put the ball-milled powder into a mold, press to form, the unit pressure is 50MPa, the holding time is 4min, and then demoulding to obtain a green body;

Step (3): Using the method of vacuum sintering, the green body prepared in step (2) is heated to 1340°C at a rate of 10°C/min under the condition of 0.01Mpa nitrogen gas and kept for 60min, and then cooled to room temperature to obtain WC-20Co cemented carbide.

As mentioned above, the present invention can be better realized. The above-mentioned embodiment is only a preferred embodiment of the present invention, and is not used to limit the scope of the present invention; Covered by the scope of protection required by the claims of the present invention.

Claims (10)

1, a kind of preparation method of WC-Co Wimet, it adopts the incorporate method of carburizing sintering, it is characterized in that may further comprise the steps:

(1) adopts dielectric barrier discharge plasma auxiliary high-energy ball milling method that W, C, Co raw material and benefit carbon are carried out ball milling by dielectric barrier discharge plasma auxiliary high-energy ball mill, obtain W, C, Co mixed powder;

(2) with described W, C, Co mixed powder press forming, obtain green compact;

(3) described green compact are put into thermal source environment sintering and prepared the WC-Co Wimet.

2, according to the preparation method of the described a kind of WC-Co Wimet of claim 1, it is characterized in that: the described W of step (1), each raw material of C, Co carry out proportioning according to WC-XCo, wherein, the span of X is 3≤X≤20, and the mass ratio of described benefit carbon and C raw material is 4%～10%.

3, preparation method according to the described a kind of WC-Co Wimet of claim 2, it is characterized in that: described dielectric barrier discharge plasma auxiliary high-energy ball mill, comprise base, abrading-ball, spring, motor, the elasticity shaft coupling, the exciting piece, frame, ball grinder, vacuum valve, front shroud, Wimet jar liner, outer jar of ball grinder, back shroud, electrode bar and plasma electrical source, described ball grinder is installed on the frame, the inside of ball grinder is placed with abrading-ball, frame is installed on the base by spring, its arranged outside has the exciting piece, drive-motor is installed on the base, and by the elasticity shaft coupling respectively with frame, the exciting piece connects, described plasma electrical source links to each other with any one bolt and the electrode bar of front shroud respectively, described Wimet jar liner is the WC-XCo Wimet, and the span of described X should be 3≤X≤20 mutually.

4, according to the preparation method of the described a kind of WC-Co Wimet of claim 2, it is characterized in that: the described dielectric barrier discharge plasma auxiliary high-energy of step (1) ball milling method may further comprise the steps:

(1.1) install the front shroud and the electrode bar of ball grinder, and front shroud is linked to each other with the positive and negative two-stage of plasma electrical source respectively with electrode bar, wherein, electrode bar connects the positive pole of plasma electrical source, and front shroud connects the negative pole of plasma electrical source;

(1.2) in ball grinder, pack into abrading-ball and W, C, Co raw material and mend carbon, when electrode bar and abrading-ball all with after W, C, Co raw material contact, build the back shroud of ball grinder;

(1.3) by vacuum valve airtight ball grinder is vacuumized, feed the discharge gas medium by vacuum valve again, the pressure in this ball grinder is 0.01～0.30MPa;

(1.4) connect plasma electrical source, regulate discharge parameter according to discharge gas medium and pressure thereof, plasma electrical source voltage is 3～30KV, discharge frequency is corresponding with voltage of supply, realize dielectric barrier discharge, and start drive-motor and drive the exciting piece, make frame and the ball grinder that is fixed on the frame vibrates simultaneously, thereby change the relative position of abrading-ball in electrode bar and the ball grinder, carry out dielectric barrier discharge plasma auxiliary high-energy ball milling.

5, according to the preparation method of the described a kind of WC-Co Wimet of claim 4, it is characterized in that: the ball powder ratio of ball milling is 10: 1～200: 1; The ball milling time is 1～9h.

6, according to the preparation method of the described a kind of WC-Co Wimet of claim 4, it is characterized in that: described discharge gas medium is argon gas, nitrogen, ammonia or methane.

7, according to the preparation method of the described a kind of WC-Co Wimet of claim 1, it is characterized in that: the mode of the press forming described in the step (2) is a die forming, and the unit pressing force is 50MPa～1000MPa.

8, according to the preparation method of the described a kind of WC-Co Wimet of claim 1, it is characterized in that: the temperature of the thermal source environment described in the step (3) is 1320～1480 ℃.

9, according to the preparation method of the described a kind of WC-Co Wimet of claim 1, it is characterized in that: the atmosphere of thermal source environment is vacuum, argon gas or nitrogen, and atmosphere pressures is 1Pa～10MPa.

10, according to the preparation method of the described a kind of WC-Co Wimet of claim 1, it is characterized in that: the agglomerating mode is that vacuum sintering or vacuum sintering are in conjunction with hot pressed sintering.

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