Preparation method of coarse-grain WC-Co-X hard alloy based on addition of ultrafine powder
阅读说明：本技术 基于添加超细粉末的粗晶WC-Co-X硬质合金的制备方法 (Preparation method of coarse-grain WC-Co-X hard alloy based on addition of ultrafine powder ) 是由 王义盛 于淞百 赵小鹏 徐文礼 张建峰 闵凡路 于 2021-09-16 设计创作，主要内容包括：本发明公开了一种基于添加超细粉末的粗晶WC-Co-X硬质合金的制备方法,包括以下步骤：步骤一,采用化学共沉淀-氢气还原工艺将添加剂X颗粒包覆在超细WC粉末或超细WC/Y粉末表面,得到超细X@WC或X@(WC/Y)粉末；步骤二,将超细X@WC或X@(WC/Y)粉末、超粗WC粉末和钴Co粉末采用球磨工艺进行混料,过滤并真空干燥得到WC/Co/(X@WC)或WC/Co/[X@(WC/Y)]粗晶复合粉末；步骤三,在步骤二得到的粗晶复合粉末中加入成型剂、造粒、压制并烧结得到粗晶WC-Co-X硬质合金或粗晶WC-Co-X-Y硬质合金。本发明的获得的硬质合金的密度、硬度和横向断裂强度优异。(The invention discloses a preparation method of a coarse-grain WC-Co-X hard alloy based on addition of ultrafine powder, which comprises the following steps: coating additive X particles on the surface of superfine WC powder or superfine WC/Y powder by adopting a chemical coprecipitation-hydrogen reduction process to obtain superfine X @ WC or X @ (WC/Y) powder; step two, mixing superfine X @ WC or X @ (WC/Y) powder, super-coarse WC powder and cobalt Co powder by adopting a ball milling process, filtering and drying in vacuum to obtain WC/Co/(X @ WC) or WC/Co/[ X @ (WC/Y) ] macrocrystalline composite powder; and step three, adding a forming agent into the coarse-grain composite powder obtained in the step two, granulating, pressing and sintering to obtain coarse-grain WC-Co-X hard alloy or coarse-grain WC-Co-X-Y hard alloy. The obtained cemented carbide of the present invention is excellent in density, hardness and transverse rupture strength.)
1. The preparation method of the coarse-grain WC-Co-X hard alloy based on adding the ultrafine powder is characterized by comprising the following steps of: the method comprises the following steps:
coating additive X particles on the surface of superfine WC powder or superfine WC/Y powder by adopting a chemical coprecipitation-hydrogen reduction process to obtain superfine X @ WC or X @ (WC/Y) powder with the particle size of 0.5-1 mu m;
step two, mixing superfine X @ WC or X @ (WC/Y) powder, super-coarse WC powder and cobalt Co powder by adopting a ball milling process, filtering and drying in vacuum to obtain WC/Co/(X @ WC) or WC/Co/[ X @ (WC/Y) ] macrocrystalline composite powder;
and step three, adding a forming agent into the coarse-grain composite powder obtained in the step two, granulating, pressing and sintering to obtain coarse-grain WC-Co-X hard alloy or coarse-grain WC-Co-X-Y hard alloy.
2. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: the grain size of the superfine WC powder or the superfine WC/Y powder is 0.4-0.6 mu m; x is nano-scale metal Co, Ni, Mg or Mn; y is carbide Cr3C2And VC or TaC, wherein the particle size is 0.2-0.3 mu m.
3. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: the preparation method of the superfine WC/Y powder comprises the following steps: the high-temperature carbonization powder is obtained by high-temperature carbonization of mixed powder of W and Y, wherein the mass ratio of Y is 4-10 wt.%, and the carbonization temperature is 1500-1600 ℃.
4. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: the chemical coprecipitation-hydrogen reduction process comprises the following steps: and carrying out chemical coprecipitation to obtain an oxide or a compound of X, reducing the oxide or the compound of X into a coating of X by hydrogen, uniformly distributing the coating on the surface of the superfine WC powder or the superfine WC/Y powder, wherein the reduction temperature of the hydrogen is 400-600 ℃, and the heat preservation time is 1-3 h.
5. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: the particle size of the ultra-coarse WC powder is 15-30 mu m, and the particle size of the cobalt Co powder is 1-2 mu m.
6. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: the ball milling process comprises the steps that the ball-material ratio is 3-4: 1, and the ball milling time is 15-24 hours.
7. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: in the coarse-grain composite powder, the content of ultra-coarse WC powder is 69-82 wt.%, the content of cobalt is 8-11 wt.%, the content of superfine X @ WC or X @ (WC/Y) powder is 10-20 wt.%, the content of X is 0-3 wt.%, and the content of Y is 0-1.0 wt.%.
8. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: in the third step, the forming agent is paraffin, the content of the paraffin is 2-3 wt.%, a low-pressure furnace is adopted for sintering, the sintering temperature is 1350-1450 ℃, the heat preservation time is 1-2 h, and the pressure is 1-5 MPa.
9. The method for preparing a macrocrystalline WC-Co-X cemented carbide based on the addition of ultrafine powders according to claim 1, characterized in that: the grain size of the coarse grain WC-Co-X hard alloy or the coarse grain WC-Co-X-Y hard alloy is more than 2 mu m, and the density is more than 14.5g/cm3(ii) a The hardness is more than 86 HRA; the transverse rupture strength is more than 2100 MPa.
Technical Field
The invention relates to a preparation method of a coarse-grain WC-Co-X hard alloy based on addition of ultrafine powder, belonging to the technical field of hard alloys.
Background
The macrocrystalline WC-Co hard alloy is a hard material with WC average grain size of 2-5 mu m and high hardness and high toughness, is known as an industrial tooth, and is widely applied to the fields of geological and mining tools, tunnel excavation cutters and the like. In the preparation process of the existing coarse-grain WC-Co hard alloy, the uneven distribution of a small amount of added components is easily caused by a flexible mechanical mixing mode, and the novel uniform mixing process of chemical methods such as chemical plating, chemical coprecipitation and the like is difficult to apply in large scale due to the complex process and high cost of the novel uniform mixing process. Therefore, the invention adopts a chemical method to coat the surface of the superfine WC particles with the additive which is beneficial to improving the alloy performance, and the composite powder is used as the additive to prepare the high-performance coarse-grain WC-Co hard alloy.
Disclosure of Invention
The invention aims to solve the technical problem that the invention provides a method for preparing a coarse-grain WC-Co-X hard alloy based on adding superfine powder, which adopts a chemical method to coat the surface of superfine WC particles with an additive beneficial to improving the alloy performance, and uses the composite powder as the additive to prepare the coarse-grain WC-Co-X hard alloy or the coarse-grain WC-Co-X-Y hard alloy with multiple components of WC and Co and the additive and multiple enhanced performance.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the preparation method of the coarse-grain WC-Co-X hard alloy based on the addition of the ultrafine powder comprises the following steps:
coating additive X particles on the surface of superfine WC powder or superfine WC/Y powder by adopting a chemical coprecipitation-hydrogen reduction process to obtain superfine X @ WC or X @ (WC/Y) powder with the particle size of 0.5-1 mu m;
step two, mixing superfine X @ WC or X @ (WC/Y) powder, super-coarse WC powder and cobalt Co powder by adopting a ball milling process, filtering and drying in vacuum to obtain WC/Co/(X @ WC) or WC/Co/[ X @ (WC/Y) ] macrocrystalline composite powder;
and step three, adding a forming agent into the coarse-grain composite powder obtained in the step two, granulating, pressing and sintering to obtain coarse-grain WC-Co-X hard alloy or coarse-grain WC-Co-X-Y hard alloy.
The grain size of the superfine WC powder or the superfine WC/Y powder is 0.4-0.6 mu m; x is nano-scale metal Co, Ni, Mg or Mn; y is carbide Cr3C2And VC or TaC, wherein the particle size is 0.2-0.3 mu m.
The preparation method of the superfine WC/Y powder comprises the following steps: the high-temperature carbonization powder is obtained by high-temperature carbonization of mixed powder of W and Y, wherein the mass ratio of Y is 4-10 wt.%, and the carbonization temperature is 1500-1600 ℃.
The chemical coprecipitation-hydrogen reduction process comprises the following steps: and carrying out chemical coprecipitation to obtain an oxide or a compound of X, reducing the oxide or the compound of X into a coating of X by hydrogen, uniformly distributing the coating on the surface of the superfine WC powder or the superfine WC/Y powder, wherein the reduction temperature of the hydrogen is 400-600 ℃, and the heat preservation time is 1-3 h.
The particle size of the ultra-coarse WC powder is 15-30 mu m, and the particle size of the cobalt Co powder is 1-2 mu m.
The ball milling process comprises the steps that the ball-material ratio is 3-4: 1, the ball milling time is 15-24 h, and the rotating speed of the ball mill is 60 rad/min.
In the coarse-grain composite powder, the content of ultra-coarse WC powder is 69-82 wt.%, the content of cobalt is 8-11 wt.%, the content of superfine X @ WC or X @ (WC/Y) powder is 10-20 wt.%, the content of X is 0-3 wt.%, and the content of Y is 0-1.0 wt.%.
In the third step, the forming agent is paraffin, the content of the paraffin is 2-3 wt.%, a low-pressure furnace is adopted for sintering, the sintering temperature is 1350-1450 ℃, the heat preservation time is 1-2 h, and the pressure is 1-5 MPa.
The grain size of the coarse grain WC-Co-X hard alloy or the coarse grain WC-Co-X-Y hard alloy is more than 2 mu m, and the density is more than 14.5g/cm3(ii) a The hardness is more than 86 HRA; the transverse rupture strength is more than 2100 MPa.
According to the invention, the nanometer WC powder is filled in gaps of the coarse WC particles, so that the liquid phase can be uniformly diffused and distributed in the initial formation stage and the WC particles are wrapped to form a uniformly distributed framework structure; meanwhile, in the dissolution-precipitation stage of sintering, the fine WC particles have higher surface energy and are preferentially dissolved in a liquid phase, and the further growth of the coarse WC grains is promoted to form complete and high-performance WC grains.
The synthesis principle is as follows: the invention prepares superfine X @ WC or X @ WC (WC/Y) powder by a chemical coprecipitation-hydrogen reduction process, wherein X in the powder can uniformly form a coating layer on the surface of WC or WC/Y; the powder is added into coarse WC and Co powder as an additive, and the uniformly mixed superfine composite powder can be uniformly distributed among coarse WC particles and fully filled into gaps among the coarse WC particles. On one hand, the superfine composite powder can effectively increase the density of a sintered blank body, and the superfine X @ WC or X @ (WC/Y) powder promotes the growth of WC grains by a dissolution-precipitation mechanism in the sintering process; on the other hand, the additionally added X and Y can be uniformly distributed among coarse WC crystal grains, so that the distribution of binder phase particles is more uniform, a uniform framework structure is formed during sintering, and the reinforcing effect of the X and Y on the crystal grains, the binder phase and the interface is fully exerted. Therefore, under the dual action of the superfine composite powder, the high-performance coarse-grain WC-Co-X hard alloy or the coarse-grain WC-Co-X-Y hard alloy is prepared.
According to the invention, the nanometer WC powder is filled in gaps of the coarse WC particles, so that the liquid phase can be uniformly diffused and distributed in the initial formation stage and the WC particles are wrapped to form a uniformly distributed framework structure; meanwhile, in the dissolution-precipitation stage of liquid phase sintering, the fine WC particles have higher surface energy and are preferentially dissolved in the liquid phase, and the further growth of the coarse WC grains is promoted to form complete and high-performance WC grains.
Compared with the prior art, the invention has the following remarkable advantages: the coarse grain WC-Co-X hard alloy or the coarse grain WC-Co-X-Y hard alloy with the grain size larger than 2 mu m is prepared by sintering superfine composite powder by a multiple strengthening mechanism, and the density, the hardness and the transverse breaking strength of the coarse grain WC-Co-X-Y hard alloy are excellent.
Drawings
Fig. 1 is a graph of the coating effect of the present invention, fig. 1 (a) and (b) are the shapes of the nano metal layer obtained in step 2 of examples 1 and 2, respectively, coated on the surface of WC grains, in fig. 1 (a), Co is mainly coated on the surface of WC in the form of a metal layer, and the part is spherical; in fig. 1 (b), Ni is mainly coated on the WC surface as spherical particles;
FIG. 2 is a metallographic representation of the morphology of alloys prepared according to the invention, (a) - (d) for examples 1-4, (e) and (f) for comparative example 1 and comparative example 2, respectively, the arrows indicate cobalt agglomeration.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting.
Example 1:
the preparation method of the coarse-grain WC-Co-X hard alloy based on the addition of the ultrafine powder comprises the following steps:
(1) 50g of ultrafine WC powder with the particle size of 0.5 mu m is uniformly coated with nano-sized Co on the surface by adopting a chemical coprecipitation-hydrogen reduction method, 22.5g of cobalt chloride is adopted as cobalt salt, 14g of ammonium oxalate is adopted as a reducing agent, the reduction temperature is 500 ℃, and the reduction is carried out for 2 hours, so that 55.6g of ultrafine Co @ WC powder (the Co content is 10wt.%) is finally obtained, as shown in a figure 1 (a). Repeating the above operation to obtain a proper amount of pre-added powder (namely superfine Co @ WC powder); as can be seen from fig. 1 (a), in the morphology of the ultrafine Co @ WC powder of this embodiment, the nano metal layer (i.e., nano-sized Co) is coated on the surface of the ultrafine WC grains to form a coating layer, and in fig. 1 (a), the nano Co is mainly coated on the surface of the WC in the form of a metal layer, and the part is spherical.
(2) Then, 375g of ultra-coarse WC powder with the particle size of 15 mu m, 83g of ultra-fine Co @ WC powder (the mass of nano Co accounts for 10wt.% of the ultra-fine Co @ WC powder) and 42g of cobalt Co powder with the particle size of 1 mu m are subjected to ball milling in a roller ball mill, anhydrous alcohol is used as a wet milling medium, the content of the anhydrous alcohol is 300mL/kg, alloy balls with the diameter of 6mm are used as the ball milling medium, and the ball-to-material ratio is 3: 1; after ball milling for 18h, 500g of a mixture was obtained (16.6 wt.% of the total powder for ultrafine WC powder, 8.4wt.% of Co by mass, 75wt.% of the total powder for ultrafine WC powder, and 1.6wt.% of nano Co by mass).
(3) Finally, 12g of paraffin is added into the mixture to be mixed evenly, granulation is carried out, and the mixture is filtered through a 80-mesh screen and pressed into a blank under the pressure of 20 MPa; sintering the blank in a low-pressure furnace at 1420 ℃, keeping the temperature for 1h and the pressure for 2MPa to obtain WC-8.4Co- (1.6 Co)nano) The metallographic morphology of the cemented carbide is shown in fig. 2 (a). As can be seen from FIG. 2(a), WC-8.4Co- (1.6 Co)nano) In the metallographic morphology of the cemented carbide, cobalt phases were distributed uniformly without an obvious cobalt pool, indicating that the cemented carbide prepared in this example had a uniform structure.
Example 2:
the preparation method of the coarse-grain WC-Co-X hard alloy based on the addition of the ultrafine powder comprises the following steps:
(1) 50g of the pretreated superfine WC powder is uniformly coated with nano-sized Ni on the surface by adopting a chemical coprecipitation-hydrogen reduction method, 22.3g of nickel chloride is used as a nickel salt, 14g of ammonium oxalate is used as a reducing agent, the reduction temperature is 500 ℃, and the superfine Ni @ WC powder with the content of 55.6gNi being 10wt.% is finally obtained by reducing for 2 hours, as shown in a figure 1 (b). Repeating the above operation to obtain proper amount of pre-added powder; as shown in fig. 1 (b), in the morphology of the ultrafine Ni @ WC powder of this embodiment, the nano metal layer (i.e., nano-sized Ni) is coated on the surface of the ultrafine WC grains to form a coating layer, and in fig. 1 (b), the nano Ni is mainly coated on the surface of the WC in spherical particles.
(2) Then, 375g of WC powder with the granularity of 15 mu m and 83gNi @ WC powder (the mass of Ni accounts for 10wt.% of the Ni @ WC powder) and 42g of Co powder with the granularity of 1 mu m are subjected to ball milling in a roller ball mill, absolute alcohol is used as a wet milling medium, the content of the absolute alcohol is 300mL/kg, alloy balls with the diameter of 6mm are used as the ball milling medium, and the ball-to-material ratio is 3: 1; after ball milling for 18h, 500g of a mixture (15 wt.% of ultrafine WC powder, 8.4wt.% of Co, 75wt.% of ultrafine WC powder, and 1.6wt.% of Ni) is obtained;
(3) finally, 12g of paraffin is added into the mixture to be mixed evenly, granulation is carried out, and the mixture is filtered through a 80-mesh screen and pressed into a blank under the pressure of 20 MPa; and sintering the blank in a low-pressure furnace at 1420 ℃, the heat preservation time is 1h, and the pressure is 2MPa to obtain the WC-8.4Co-1.6Ni hard alloy, wherein the metallographic morphology of the alloy is shown in a figure 2 (b). As can be seen from fig. 2(b), in the metallographic morphology of the WC-8.4Co-1.6Ni cemented carbide, the cobalt phase is distributed uniformly, and there is no distinct cobalt pool, which indicates that the cemented carbide prepared in this example has a uniform structure.
Example 3
The preparation method of the coarse-grain WC-Co-X hard alloy based on the addition of the ultrafine powder comprises the following steps:
(1) 50g of superfine Co/Y powder with the particle size of 0.6 mu m is uniformly coated with Co with a nanometer size on the surface by adopting a chemical coprecipitation-hydrogen reduction method, 22.5g of cobalt chloride is adopted as cobalt salt, 14g of ammonium oxalate is adopted as a reducing agent, the reduction temperature is 400 ℃, reduction is carried out for 1h, finally 55.6g of superfine Co @ WC/Y powder (the Co content is 10wt.%) is obtained, and the operation is repeated to obtain a proper amount of pre-added powder (namely the superfine Co @ WC/Y powder with the particle size of 0.8 mu m).
The preparation method of the superfine WC/Y powder comprises the following steps: the powder is obtained by high-temperature carbonization of mixed powder of W and Y, wherein the carbonization temperature is 1600 ℃, and the mass ratio of Y is 4 wt.%. Y in this example is Cr, and Cr is obtained by carbonization3C2。
(2) Then, ball milling 400g of ultra-coarse WC powder with the particle size of 15 [ mu ] m, 55.6g of ultra-fine Co @ WC/Y powder (the mass of nano Co accounts for 10 wt% of the ultra-fine Co @ WC/Y powder, the mass of WC/Y accounts for 90 wt% of the ultra-fine Co @ WC/Y powder, the mass of Y accounts for 4 wt% of WC/Y) and 44.4g of cobalt Co powder with the particle size of 1 [ mu ] m in a roller ball mill, taking absolute alcohol as a wet milling medium, wherein the content of the absolute alcohol is 300mL/kg, alloy balls with the diameter of 6mm are selected as the ball milling medium, and the ball-to-material ratio is 3: 1; after ball milling for 18h, 500g of a mixture was obtained (9.6 wt.% of the total powder for ultrafine WC powder, 8.8wt.% of Co by mass, 80wt.% of the total powder for ultrafine WC powder, 1.2wt.% of the total powder for nano Co, and 0.4wt.% of the total powder for Y).
(3) Finally, 12g of paraffin is added into the mixture, mixed evenly and manufacturedGranulating, sieving with 80 mesh sieve, and pressing under 20MPa to obtain blank; sintering the blank in a low-pressure furnace at 1350 ℃, keeping the temperature for 1h and the pressure for 5MPa to obtain WC-10Co-0.4Cr3C2The metallographic morphology of the cemented carbide is shown in FIG. 2 (c). As can be seen, WC-10Co-0.4Cr3C2In the metallographic morphology of the cemented carbide, cobalt phases were distributed uniformly without an obvious cobalt pool, indicating that the cemented carbide prepared in this example had a uniform structure.
Example 4
The preparation method of the coarse-grain WC-Co-X hard alloy based on the addition of the ultrafine powder comprises the following steps:
(1) 50g of superfine WC/Y powder with the granularity of 1 mu m is uniformly coated with nano-sized Co on the surface by adopting a chemical coprecipitation-hydrogen reduction method, 22.5g of cobalt chloride is adopted as cobalt salt, 14g of ammonium oxalate is adopted as a reducing agent, the reduction temperature is 600 ℃, reduction is carried out for 3 hours, 55.6g of superfine Co @ WC/Y powder (the Co content is 10wt.%) is finally obtained, and the operation is repeated to obtain a proper amount of pre-added powder (namely the superfine Co @ WC/Y powder).
The preparation method of the superfine WC/Y powder comprises the following steps: the powder is obtained by high-temperature carbonization of mixed powder of W and Y, wherein the carbonization temperature is 1500 ℃, and the mass proportion of Y is 10 wt.%. In this example, Y is Ta, and TaC is obtained after carbonization.
(2) Then, ball milling 400g of ultra-coarse WC powder with the particle size of 15 [ mu ] m, 55.6g of ultra-fine Co @ WC/Y powder (the mass of nano Co accounts for 10 wt% of the ultra-fine Co @ WC/Y powder, the mass of WC/Y accounts for 90 wt% of the ultra-fine Co @ WC/Y powder, the mass of Y accounts for 10 wt% of WC/Y) and 44.4g of cobalt Co powder with the particle size of 1 [ mu ] m in a roller ball mill, taking absolute alcohol as a wet milling medium, wherein the content of the absolute alcohol is 300mL/kg, alloy balls with the diameter of 6mm are selected as the ball milling medium, and the ball-to-material ratio is 3: 1; after ball milling for 18h, 500g of a mixture was obtained (9.0 wt.% of the total powder for ultrafine WC powder, 8.8wt.% of Co by mass, 80wt.% of the total powder for ultrafine WC powder, 1.2wt.% of the total powder for nano Co, 1.0wt.% of the total powder for Y).
(3) Finally, 10g of paraffin is added into the mixture to be mixed evenly, granulation is carried out, and the mixture is filtered through a 80-mesh screen and pressed into a blank under the pressure of 20 MPa; and (3) sintering the blank in a low-pressure furnace at 1450 ℃, the heat preservation time is 1.5h, and the pressure is 1MPa to obtain the WC-10Co-1.0TaC hard alloy, wherein the metallographic morphology of the alloy is shown in a figure 2 (d). As can be seen from the figure, in the metallographic morphology of the WC-10Co-1.0TaC hard alloy, the cobalt phase is uniformly distributed, and no obvious cobalt pool is present, which indicates that the hard alloy prepared by the embodiment has a uniform structure.
Comparative example 1
The differences between this comparative example and example 1 are: and (3) directly adopting the ball milling process in the step (3) to prepare WC-10Co, wherein the superfine WC powder prepared in the step (1) is not added, and the metallographic morphology of the prepared alloy is shown in a figure 2 (e).
Comparative example 2
The differences between this comparative example and example 1 are: and (3) preparing WC-10Co by adopting the ball milling process in the step (3), wherein 15wt.% of the superfine WC powder prepared in the step (1) is added, and the metallographic morphology of the prepared alloy is shown in a figure 2 (f).
The results of the performance tests performed on examples 1 to 4 and comparative examples 1 to 2 are shown in table 1, and it can be seen from the table that the average grain size of examples 1 to 4 is greater than 2 μm, and the density, hardness and transverse rupture strength are all improved. In example 1, macrocrystalline WC-8.4Co- (1.6 Co) prepared by adding ultrafine Co @ WC powder was compared to comparative example 1nano) Partial crystal grains of the hard alloy are refined to form the hard alloy with a double-crystal structure, the density is higher, the hardness is improved by 1.1HRA, and the strength is improved by 285 MPa; compared with the cemented carbide of comparative example 2 (the cemented carbide with only the ultrafine WC powder added), the performance of the macrocrystalline cemented carbide of example 1 is also greatly improved. In example 2, compared with comparative example 1, the hardness of the macrocrystalline WC-8.4Co-1.6Ni hard alloy is improved by 0.5HRA, and the strength is improved by 455 MPa; compared with the comparative example 2, the hardness of the coarse-grain WC-8.4Co-1.6Ni hard alloy is improved by 0.5HRA, and the strength is improved by 246 MPa. In example 3, coarse-grained WC-10Co-0.4Cr, compared to comparative example 13C2The hardness of the hard alloy is improved by 1.3HRA, and the strength is improved by 311 MPa; compared with the comparative example 2, the hardness of the coarse-grain WC-8.4Co-1.6Ni hard alloy is improved by 1.3HRA, and the strength is improved by 102 MPa. In example 4, compared to comparative example1, the hardness of the coarse-grain WC-10Co-0.4TaC hard alloy is improved by 0.6HRA, and the strength is improved by 561 MPa; compared with the comparative example 2, the hardness of the coarse-grain WC-10Co-0.4TaC hard alloy is improved by 0.6HRA, and the strength is improved by 352 MPa. In addition, as shown in fig. 2, the cobalt phases in examples 1 to 4 are uniformly distributed, and the alloy prepared in the comparative example has a large number of cobalt pools formed by the aggregation of the cobalt phases, which indicates that the cemented carbide prepared by the present invention has a uniform structure.
TABLE 1 Performance test results for examples 1-4 and comparative examples 1-2
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.