Preparation method of Nd2O3 and CeO2 co-doped WC-8Co cemented carbide and sealing element

Abstract

The application relates to the technical field of tungsten-based hard alloys, and discloses a preparation method of Nd2O3 and CeO2 co-doped WC-8Co hard alloy, which comprises the following steps: step 1, Nd2O3 / CeO2-W doped powder is prepared by using a wet chemical method, and the preparation specific process is as follows: rare earth oxide nitrate and APT weighed are respectively dissolved in deionized water, and a magnetic stirrer is continuously and violently stirred to mix, so that the rare earth elements and the APT are fully reacted and mixed; then, a vacuum air oven is used for drying to obtain a precursor powder; after the precursor powder is ground in a jade mortar, the powder is first kept at 480 DEG C to 520 DEG C in a nitrogen gas pipe furnace for 2h to 3h, and the powder is changed into a mixed oxide containing rare earth oxide Nd2O3 / CeO2 and tungsten oxide. The preparation method of the Nd2O3 and CeO2 co-doped WC-8Co hard alloy has the advantages that the prepared Nd2O3 and CeO2 co-doped WC-8Co hard alloy has high friction and wear resistance and long service life, and the method provides a new idea for the research of WC-based hard alloys co-doped with multiple additives.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of tungsten-based hard alloys, in particular to a preparation method of an Nd2O3 and CeO2 co-doped WC-8Co hard alloy and a sealing element. BACKGROUND

[0002] The tungsten-based hard alloy for sealing elements refers to a metal-based composite material prepared by preparing a composite powder according to a certain proportion of WC (a carbide of refractory metal W) and Co, Ni and Fe (metallic binders) and then performing a powder sintering process. The tungsten-based hard alloy has high hardness and toughness, corrosion resistance and heat resistance, and can still maintain high hardness during high-temperature working, and is widely applied to the preparation of high-performance mechanical seals and mine alloys. The mechanical properties of the tungsten-based alloy are positively correlated with the grain size of the tungsten carbide, and the grain size of the tungsten carbide is positively correlated with the powder particle size of the tungsten carbide before sintering. The tungsten carbide is obtained by high-temperature carbonization of tungsten powder, and the particle size of the tungsten carbide is positively correlated with the particle size of the tungsten powder. Therefore, the preparation process of the tungsten powder body needs to be researched for high-performance hard alloy materials.

[0003] The rare earth modified hard alloy refers to an alloy prepared by adding a small amount of trace rare earth elements (Nd, Y, La and Ce) to the raw material WC and Co powder body and then performing powder sintering. Research shows that the addition of the rare earth elements can inhibit the growth of WC grains, absorb oxygen elements to purify the grain boundaries, reduce the porosity, and improve the solubility and wettability of the WC grains in the Co binder phase. In the WC-8Co hard alloy, the trace doping of the rare earth oxides Nd2O3, CeO2, Y2O3 and La2O3 can not only inhibit the grain growth, but also play a synergistic toughening role. The second phase in the Nd2O3, CeO2, Y2O3 and La2O3 modified hard alloy prepared based on the wet chemical method realizes molecular-level mixing with the WC grains, so that the alloy performance is significantly improved. However, the research on the performance and microstructure of the two-phase or even multi-phase co-doped hard alloy is relatively less, and therefore the Nd2O3 / CeO2 modified hard alloy is prepared by using the wet chemical method in the application, so as to study the influence of the two-phase doping on the alloy performance and microstructure. At the same time, the WC-8Co-Nd2O3-CeO2 block hard alloy is prepared by using the SPS sintering, the discharge plasma generated instantaneously makes each particle in the sintered body generate uniform self-heating and activates the particle surface, the rapid heating and cooling rate and short holding time can inhibit the growth of the particles in the hard alloy, and finally the large-size block hard alloy with excellent friction and wear resistance is obtained.

[0004] The application adopts chemical doping and spark plasma sintering (SPS) to prepare WC-8Co-Nd2O3-CeO2 cemented carbide material, studies the influence of co-doping of Nd2O3 and CeO2 on the performance of WC-8Co cemented carbide, prepares WC-8Co-Nd2O3-CeO2 alloys with different doping contents of Nd2O3 and CeO2, finally uses the developed WC-8Co-Nd2O3-CeO2 cemented carbide to manufacture mechanical seal rings, carries out water wear resistance experiments, and compares the anti-friction and wear resistance of the seal rings made of two materials. The research result provides a new idea for the research of WC-based cemented carbide with co-doping of multiple additives. SUMMARY

[0005] To solve the technical problems in the background art, the application provides a preparation method of Nd2O3 and CeO2 co-doped WC-8Co cemented carbide and a seal.

[0006] The application adopts the following technical scheme: a preparation method of Nd2O3 and CeO2 co-doped WC-8Co cemented carbide, comprising the following steps:

[0007] Step 1: a wet chemical method is used to prepare Nd2O3 / CeO2-W doped powder, and the specific process flow is as follows: firstly, the required W is converted into the mass of ammonium paratungstate H42N10O42W12·xH2O (APT), and Nd2O3 and CeO2 are converted into the mass of neodymium nitrate and cerium nitrate respectively; the weighed rare earth oxide nitrate and APT are dissolved with deionized water, and a magnetic stirrer is used to continuously and vigorously stir the mixture to ensure that the rare earth elements and APT are fully mixed; then the precursor powder is obtained by drying in a vacuum air oven;

[0008] After the precursor powder is ground in a marquis mortar, it is first heated at 480-520 DEG C for 2-3 hours in a nitrogen gas pipe furnace, and the powder becomes a mixed oxide containing rare earth oxide Nd2O3 / CeO2 and tungsten oxide. Then it is reduced in a high vacuum pipe sintering furnace, and finally cooled to room temperature under hydrogen protection to obtain W-Nd2O3-CeO2 composite powder. In the experiment, in order to control the content of Nd2O3-CeO2 in W cemented carbide, the mass ratio of APT to neodymium nitrate and cerium nitrate is 3250:83 on the basis of stoichiometric calculation of W-Nd2O3-CeO2 powder preparation;

[0009] Step 2, the W-Nd2O3-CeO2 powder is carbonized by high temperature carbonization process, and the specific process flow is as follows: first, the W-Nd2O3-CeO2 powder, nano graphite powder and planetary ball mill are mixed for 6-8 hours to prepare W-Nd2O3-CeO2-C composite powder; then the carbonization is carried out by putting the W-Nd2O3-CeO2-C composite powder into a tube furnace, heating to a set temperature, and keeping for 2-3 hours under vacuum condition to obtain WC-Nd2O3-CeO2 powder. The phase detection XRD of the powder before and after carbonization is shown in the accompanying drawings. After carbonization, the W peak disappears completely, and only the WC peak is detected in the XRD spectrum, indicating that the W-Nd2O3-CeO2 powder is completely carbonized after heating to 1800°C for 2 hours. Figure 1

[0010] Step 3, the WC-Nd2O3-CeO2 powder and Co powder are mixed by planetary ball mill;

[0011] Step 4, WC-8Co-0.45Nd2O3-0.5CeO2 cemented carbide small samples are prepared by SPS process, and the densification of the alloy is realized at different temperatures.

[0012] Preferably, in step 1, the stirring and mixing is carried out for 12-15 hours, and the drying is carried out in an oven at a temperature of 75-85°C for 3-4 hours.

[0013] Preferably, in step 1, the reducing H2 is high-purity hydrogen (purity = 99.999%), the reducing temperature is 600-700°C, the heating rate is 10-15°C / min, and the time is 4-6 hours.

[0014] Preferably, in step 2, the W-Nd2O3-CeO2-C composite powder is put into a tube furnace, and heated to 1800-2000°C at a rate of 10-15°C / min, and kept for 2-3 hours under vacuum condition.

[0015] Preferably, in step 3, the ball milling process parameters are ball-to-material ratio of 4-6:1-3, rotation speed of 350-500 rpm, and ball milling time of 48-60 hours, and the ball milling is carried out using a cemented carbide milling jar and milling balls.

[0016] Preferably, the mass fraction of Co and Nd2O3-CeO2 in the C-Co-Nd2O3-CeO2 composite powder is set to 0.5-0.8 wt.%.

[0017] Preferably, in step 4, the SPS process parameters are: 50-70 MPa, heating rate of 60-80°C / min, sintering temperature of 1300-1400°C, holding time of 10-20 min, and finally the sintering temperature is cooled to room temperature.​

[0018] The application further provides a sealing element prepared from the WC-8Co-Nd2O3-CeO2 cemented carbide prepared by the preparation method.

[0019] Compared with the prior art, the application has the beneficial effects that:

[0020] The preparation method of the Nd2O3 and CeO2 co-doped WC-8Co cemented carbide has the advantages that the Nd2O3 and CeO2 co-doped WC-8Co cemented carbide prepared by the method has strong anti-friction wear resistance and long service life, and provides a new idea for the research of WC-based cemented carbide co-doped with multiple additives. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is an XRD pattern of the W-Nd2O3-CeO2 powder after carbonization in Embodiment 1 of the application. DETAILED DESCRIPTION

[0022] Hereinafter, the application will be further described in combination with the drawings and specific embodiments, and it should be noted that the following described embodiments or technical features can be combined in any manner to form new embodiments without conflict.

[0023] Embodiment 1:

[0024] In this embodiment, the Nd2O3 / CeO2-W powder is prepared by a wet chemical method, and the specific process flow of the preparation is as follows:

[0025] First, the required W is converted into the mass of ammonium paratungstate H42N10O42W12·xH2O (APT), and Nd2O3 and CeO2 are converted into the mass of neodymium nitrate and cerium nitrate, respectively. The weighed rare earth oxide nitrate and APT are dissolved with deionized water, and the magnetic stirrer is continuously stirred vigorously for 12 h to ensure that the rare earth elements and APT are fully mixed. Then, the precursor powder is dried in a vacuum air oven at 75℃ for 3 h. After the precursor powder is ground in a marquise mortar, it is first heated at 480℃ for 2 h in a nitrogen-tube furnace, and the powder becomes a mixed oxide containing rare earth oxide Nd2O3 / CeO2 and tungsten oxide. Then, it is placed in a high-vacuum tube sintering furnace for reduction. The reduction H2 is high-purity hydrogen (purity = 99.999%), the reduction temperature is 600℃, the heating rate is 10℃ / min, the time is 4 h, and finally it is cooled to room temperature under hydrogen protection to obtain W-Nd2O3-CeO2 composite powder. In the experiment, in order to control the content of Nd2O3-CeO2 in the W cemented carbide, the mass ratio of APT to neodymium nitrate and cerium nitrate is 3250:83 on the basis of the stoichiometric calculation of the preparation of W-Nd2O3-CeO2 powder.

[0026] The W-Nd2O3-CeO2 powder is carbonized by a high-temperature carbonization process, and the specific process flow is as follows: first, the W-Nd2O3-CeO2 powder, nano graphite powder and 6h are mixed by a planetary ball mill to prepare W-Nd2O3-CeO2-C composite powder; then the carbonization is put into a tube furnace, and the temperature is raised to 1800℃ at a rate of 10℃ / min, and the temperature is kept for 2h under vacuum condition. The phase detection XRD of the powder before and after carbonization is shown in the attached Figure 1 The W peak completely disappears after carbonization, and only WC peak is detected in the XRD spectrum, indicating that the W-Nd2O3-CeO2 powder is completely carbonized after heating to 1800℃ for 2h;

[0027] The preparation process of WC-Co-Nd2O3-CeO2 composite powder adopts ball milling, and WC-Nd2O3-CeO2 powder and Co powder are mixed by a planetary ball mill. The ball milling process parameters are ball-to-material ratio of 4:1, rotation speed of 350rpm, ball milling time of 48h, and hard alloy ball mill tank and ball mill ball are used for ball milling. The mass fraction of Co and Nd2O3-CeO2 in WC-Co-Nd2O3-CeO2 composite powder is set to 0.5wt.% respectively;

[0028] The WC-8Co-0.5Nd2O3-0.5CeO2 hard alloy sample is prepared by SPS process, and the densification of the alloy is realized at different temperatures. The SPS process parameters are: 50MPa, heating rate 60℃ / min, sintering temperature 1300℃, holding time 10min, and finally the sintering temperature is cooled to room temperature with the furnace.

[0029] Example 2:

[0030] This example uses a wet chemical method to prepare Nd2O3 / CeO2-W powder, and the specific preparation process is as follows:

[0031] Firstly, according to the mass of the required W converted into ammonium paratungstate H42N10O42W12xH2O (APT), Nd2O3 and CeO2 are converted into the mass of neodymium nitrate and cerium nitrate respectively. The weighed rare earth oxide nitrate and APT are dissolved with deionized water respectively, and the mixture is continuously stirred vigorously by a magnetic stirrer for 12 h to ensure that the rare earth elements and APT are fully reacted and mixed. Then the precursor powder is dried in a vacuum air oven at 75℃ for 3 h. After the precursor powder is ground in a marquise mortar, it is first heated in a nitrogen-tube furnace at 480℃ for 2 h, and the powder becomes a mixed oxide containing rare earth oxide Nd2O3 / CeO2 and tungsten oxide. Then it is placed in a high-vacuum tube sintering furnace for reduction. The reducing H2 is high-purity hydrogen (purity = 99.999%), the reduction temperature is 600℃, the heating rate is 10℃ / min, the time is 4 h, and finally it is cooled to room temperature under hydrogen protection to obtain a W-Nd2O3-CeO2 composite powder. In order to control the content of Nd2O3-CeO2 in the W hard alloy, the mass ratio of APT to neodymium nitrate and cerium nitrate is 3250:83 on the basis of stoichiometric calculation of the preparation of W-Nd2O3-CeO2 powder in the experiment;

[0032] The W-Nd2O3-CeO2 powder is carbonized by high-temperature carbonization process. The specific process flow is as follows: firstly, the W-Nd2O3-CeO2 powder and nano-graphite powder are mixed by a planetary ball mill for 6 h to prepare W-Nd2O3-CeO2-C composite powder; then the W-Nd2O3-CeO2-C composite powder is placed in a tube furnace and heated to 1800℃ at a rate of 10℃ / min under vacuum for 2 h. The phase detection XRD of the powder before and after carbonization is shown in FIG. 2. After carbonization, the W peak disappears completely, and only the WC peak is detected in the XRD spectrum, indicating that the W-Nd2O3-CeO2 powder is completely carbonized after heating to 1800℃ for 2 h; Figure 1

[0033] The preparation process of WC-Co-Nd2O3-CeO2 composite powder adopts ball milling. WC-Nd2O3-CeO2 powder and Co powder are mixed by a planetary ball mill. The ball milling process parameters are ball-to-material ratio of 4:1, rotation speed of 350 rpm, and ball milling time of 48 h. Hard alloy ball milling tank and ball milling balls are used to ball mill WC-Co-Nd2O3-CeO2 composite powder. The mass fraction of Co and Nd2O3-CeO2 in the WC-Co-Nd2O3-CeO2 composite powder is set to 0.6wt.% respectively;

[0034] ​SPS process was used to prepare WC-8Co-0.6Nd2O3-0.6CeO2 cemented carbide small samples, and the densification of the alloy was realized at different temperatures. The SPS process parameters are: 50 MPa, heating rate 60 ℃ / min, sintering temperature set to 1350 ℃, holding time 10 min, and finally the sintering temperature is cooled to room temperature with the furnace.

[0035] Example 3:

[0036] This embodiment uses a wet chemical method to prepare Nd2O3 / CeO2-doped W powder, and the specific process flow of the preparation is as follows:

[0037] First, according to the mass of the required W converted into ammonium paratungstate H42N10O42W12·xH2O (APT), the mass of Nd2O3 and CeO2 is converted into neodymium nitrate and cerium nitrate respectively. The weighed rare earth oxide nitrate and APT are dissolved with deionized water respectively, and the magnetic stirrer is continuously stirred vigorously for 12 h to ensure that the rare earth elements and APT are fully mixed. Then, the precursor powder is obtained by drying in a vacuum air oven at 75℃ for 3h. After grinding the precursor powder in a agate mortar, first in a nitrogen atmosphere tube furnace at 480℃ for 2h, the powder becomes a mixed oxide containing rare earth oxide Nd2O3 / CeO2 and tungsten oxide. Then put it into a high vacuum tube sintering furnace for reduction. The reducing H2 is high-purity hydrogen (purity = 99.999%), the reduction temperature is 600℃, the heating rate is 10℃ / min, the time is 4h, and finally it is cooled to room temperature under hydrogen protection, to obtain W-Nd2O3-CeO2 composite powder. In order to control the content of Nd2O3-CeO2 in W cemented carbide, the mass ratio of APT to neodymium nitrate and cerium nitrate is 3250:83 based on the stoichiometric calculation of W-Nd2O3-CeO2 powder preparation in the experiment;

[0038] The W-Nd2O3-CeO2 powder is carbonized by high-temperature carbonization process, and the specific process flow is as follows: first, the W-Nd2O3-CeO2 powder and nano graphite powder are mixed by planetary ball mill for 6h to prepare W-Nd2O3-CeO2-C composite powder; then the carbonized W-Nd2O3-CeO2-C composite powder is put into a tube furnace, and the temperature is raised to 1800℃ at a rate of 10℃ / min, and the temperature is kept for 2h under vacuum condition. The phase detection XRD of the powder before and after carbonization is shown in FIG. 1. Figure 1 After carbonization, the W peak completely disappears, and only the WC peak is detected in the XRD spectrum, indicating that the W-Nd2O3-CeO2 powder is completely carbonized after heating to 1800℃ for 2h;

[0039] The WC-Co-Nd2O3-CeO2 composite powder is prepared by ball milling. WC-Nd2O3-CeO2 powder and Co powder are mixed by a planetary ball mill. The ball milling process parameters are a ball-to-material ratio of 4:1, a rotation speed of 350 rpm, and a ball milling time of 48 h. Hard alloy milling jars and milling balls are used for ball milling. The mass fractions of Co and Nd2O3-CeO2 in the WC-Co-Nd2O3-CeO2 composite powder are set to 0.8 wt.%, respectively.

[0040] The WC-8Co-0.8Nd2O3-0.8CeO2 cemented carbide sample is prepared by the SPS process to realize densification of the alloy at different temperatures. The SPS process parameters are: 50 MPa, a heating rate of 60 ℃ / min, a sintering temperature of 1400 ℃, a holding time of 10 min, and finally the sintering temperature is cooled to room temperature with the furnace.

[0041] Comparative Example

[0042] The WC powder and the Co powder are directly mixed by a planetary ball mill. The ball milling process parameters are a ball-to-material ratio of 4:1, a rotation speed of 350 rpm, and a ball milling time of 48 h. Hard alloy milling jars and milling balls are used for ball milling of Co in the WC-Co composite powder. The WC-8Co cemented carbide sample is prepared by the SPS process to realize densification of the alloy at different temperatures. The SPS process parameters are: 50 MPa, a heating rate of 60 ℃ / min, a sintering temperature of 1400 ℃, a holding time of 10 min, and finally the sintering temperature is cooled to room temperature with the furnace.

[0043] The friction and wear properties of the WC-8Co-Nd2O3-CeO2 cemented carbide are analyzed and tested by using an SFT-2M ball-on-disc friction tester. The counter grinding ball used is a Si3N4 ball with a diameter of 4 mm. The WC-8Co-Nd2O3-CeO2 cemented carbide sample in the example is subjected to ball-on-disc reciprocating friction and wear performance testing in water. The test conditions are: a friction time of 800 min, a normal load of 700 N, a reciprocating speed of 500 rpm, and a reciprocating length of 10 mm. After the test, the surface area of the wear scar is obtained using a step tester, and the wear rate of the WC-8Co-Nd2O3-CeO2 cemented carbide sample is calculated. The friction coefficient is obtained by using the SFT-2M ball-on-disc friction tester. Table 1 shows the average sliding friction coefficient and the wear rate of the WC-8Co-Nd2O3-CeO2 cemented carbide samples in Examples 1, 2, and 3.

[0044]

[0045] From the above data, it can be seen that the WC-8Co-Nd2O3-CeO2 cemented carbide sample of the application has excellent low friction coefficient and low friction wear rate. The WC-8Co-Nd2O3-CeO2 cemented carbide sample of the example is subjected to ball-disk reciprocating friction and wear performance test in water environment, and the wear resistance of the WC-8Co-Nd2O3-CeO2 cemented carbide sample of the application is improved by 2 orders of magnitude compared with WC-8Co. The friction coefficient of the WC-8Co-Nd2O3-CeO2 cemented carbide sample in water environment is about 0.04. Compared with the friction coefficient of WC-8Co in water, the friction coefficient and wear rate of the WC-8Co-Nd2O3-CeO2 cemented carbide sample in water are smaller, which indicates that doping Nd2O3 and CeO2 in WC-8Co can significantly improve the friction and wear performance of the cemented carbide sample.

[0046] The WC-8Co cemented carbide sample doped with Nd2O3 and CeO2 has extremely low friction coefficient, long service life and high reliability, and will have great significance for improving the lubrication state of the sealed friction end face moving parts, solving the bottleneck problem restricting the reliability and service life of the sealed lubrication technology, and developing long service life sealing parts.

[0047] The above embodiments are only preferred embodiments of the application, and cannot be used to limit the protection scope of the application. Any non-essential changes and substitutions made by those skilled in the art on the basis of the application shall fall within the protection scope of the application.

Claims

1. A method for producing an Nd203 and CeO2 co-doped WC-8Co cemented carbide, characterized by, Comprising the following steps: Step 1, using wet chemical method to prepare doped Nd2O3 / CeO2-W powder, the preparation process is as follows: the weighed rare earth nitrate and APT are dissolved in deionized water respectively, and the mixture is continuously stirred by a magnetic stirrer to ensure that the rare earth elements and APT are fully mixed; then the precursor powder is obtained by drying in a vacuum air oven; After the precursor powder is ground in a garnet mortar, it is first heated at 480-520°C for 2-3h in a nitrogen-tube furnace, and then reduced in a high-vacuum tube sintering furnace, and finally cooled to room temperature under hydrogen protection to obtain W-Nd2O3-CeO2 composite powder; Step 2, carbonizing the above W-Nd2O3-CeO2 powder by high-temperature carbonization process, the specific process is as follows: first, using nano-graphite powder as carbonizing agent, mixing W-Nd2O3-CeO2 powder and nano-graphite powder for 6-8h by planetary ball mill to prepare W-Nd2O3-CeO2-C composite powder; carbonization is to put the W-Nd2O3-CeO2-C composite powder into a tube furnace, heat to the set temperature, and keep it at temperature for 2-3h under vacuum condition to obtain WC-Nd2O3-CeO2 powder; Step 3, the preparation process of WC-Co-Nd2O3-CeO2 composite powder adopts ball milling, and WC-Nd2O3-CeO2 powder and Co powder are mixed by planetary ball mill; Step 4, using SPS process to prepare WC-8Co-0.5Nd2O3-0.5CeO2 or WC-8Co-0.6Nd2O3-0.6CeO2 or WC-8Co-0.8Nd2O3-0.8CeO2 hard alloy small samples, and the densification of the alloy is realized at different temperatures.

2. The method for preparing a Nd₂O₃ and CeO₂ co-doped WC-8Co cemented carbide as described in claim 1, characterized in that, In step 1, the mixture is stirred for 12-15h, and then dried in an oven at a temperature of 75-85°C for 3-4h.

3. The method for preparing a Nd₂O₃ and CeO₂ co-doped WC-8Co cemented carbide as described in claim 1, characterized in that, In step 1, the reducing H2 is high-purity hydrogen with a purity of 99.999%, the reducing temperature is 600-700°C, the heating rate is 10-15°C / min, and the time is 4-6h.

4. The method for preparing a Nd₂O₃ and CeO₂ co-doped WC-8Co cemented carbide as described in claim 1, characterized in that, In step 2, the W-Nd2O3-CeO2-C composite powder is placed in a tube furnace, and heated to 1800-2000°C at a rate of 10-15°C / min, and kept at temperature for 2-3h under vacuum condition.

5. The method for preparing a Nd₂O₃ and CeO₂ co-doped WC-8Co cemented carbide as described in claim 1, characterized in that, In step 3, the ball milling process parameters are ball-to-material ratio of 4-6:1-3, rotation speed of 350-500 rpm, and ball milling time of 48-60h, and hard alloy ball milling jar and ball are used for ball milling.

6. The method for preparing a Nd₂O₃ and CeO₂ co-doped WC-8Co cemented carbide as described in claim 1, characterized in that, In step 4, the SPS process parameters are: 50-70MPa, heating rate of 60-80°C / min, sintering temperature of 1300-1400°C, holding time of 10-20min, and finally the sintering temperature is cooled to room temperature.

7. A seal made of a WC-8Co-Nd2O3-CeO2 cemented carbide produced by the method according to any one of claims 1-6.

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