High-strength and high-toughness hard alloy material as well as preparation method and application thereof

Abstract

The invention discloses a high-strength and high-toughness hard alloy material and a preparation method and application thereof.The hard alloy material is composed of a WC hard phase, a CoNiCrCu binding phase and trace rare earth Sm, the content of the CoNiCrCu binding phase ranges from 5.5 wt% to 5.9 wt%, and the content of the rare earth Sm ranges from 0.1 wt% to 0.5 wt%; wC grains are of a bicrystal structure, that is, 0.1-0.5 [mu] m superfine WC grains are distributed among the large WC grains; the binding phase is basically of an FCC structure, and a coherent interface exists between the hard phase and the binding phase. The preparation method comprises the following steps: preparation of a precursor solution, spray drying, two-step reduction, ball milling and mixing, drying and granulation, compression molding, and degreasing and sintering. According to the hard alloy material for the down-the-hole drill, prepared through the method, the hardness ranges from 90.2 HRA to 91 HRA, the bending strength ranges from 3000 MPa to 3500 MPa, and the fracture toughness ranges from 13.8 MPa.m < 1 / 2 > to 15.3 MPa.m < 1 / 2 >.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of powder metallurgy, and particularly relates to a high-strength and high-toughness cemented carbide material and a preparation method and application thereof. BACKGROUND

[0002] Cemented carbide is generally composed of high-hardness carbide phase and ductile metal binder phase, and has comprehensive performances such as high hardness, high strength, excellent wear resistance and red hardness, and is thus widely used in the field of mine exploitation. As a key component in mine drilling and mining equipment, the service performance of the hard metal ball tooth of a down-the-hole drill directly affects the tunneling efficiency and construction safety. When the high-wind down-the-hole drill hard metal tooth drills in hard and strong abrasive rock layers, the ball tooth not only faces severe friction with hard rock, but also needs to withstand repeated high impact fatigue stress and shear load, which puts higher requirements on the friction and wear resistance and impact resistance of the hard metal ball tooth. Therefore, the hard metal ball tooth must have high hardness, wear resistance and high strength and toughness to prevent the ball tooth from cracking, fatigue damage or wear failure.

[0003] However, hardness and toughness are a pair of contradictions in the production of cemented carbide, and both cannot be considered at the same time. In order to make the hard metal ball tooth have high wear resistance, the grain is usually refined, but the binder phase free path thickness is reduced due to the grain refinement, which leads to the reduction of the toughness of the alloy. Although the toughness of the hard metal ball tooth can be improved by increasing the Co content or increasing the grain size, the hardness is also easily reduced, resulting in insufficient wear resistance. SUMMARY

[0004] In view of the problems of insufficient wear resistance, bending strength and fracture toughness of the cemented carbide material in the prior art, a first object of the present application is to provide a high-strength and high-toughness cemented carbide material. The cemented carbide material provided by the present application uses Ni, Cr and Cu to replace part of Co to form a multi-main-element CoNiCrCu binder phase, which forms a coherent interface on the surface layer of the WC grain, realizes grain boundary strengthening, and adds trace nanometer rare earth oxide particles to the multi-main-element binder phase. These particles can improve the wear resistance of the binder phase. At the same time, in view of the performance defects of single grain structure, a bicrystal cemented carbide with coarse and fine grains is prepared through raw material design and process control. This bicrystal structure not only meets the requirements of hardness and wear resistance, but also has high toughness and meets the requirements of impact resistance, which has important research significance and broad engineering application prospect.

[0005] A second object of the present application is to provide a preparation method of a high-strength and high-toughness cemented carbide material. The preparation method of the present application is simple and controllable, and is suitable for industrial production.

[0006] A third object of the present application is to provide an application of a high-strength and high-toughness cemented carbide material.

[0007] To achieve the above object, the present application adopts the following technical solutions:

[0008] The present application provides a high-strength and high-toughness hard alloy material, which comprises the following components in percentage by mass: Co: 2-3%, Ni: 2-3%, Cr: 0.2-1%, Cu: 0.2-1%, Sm: 0.1-1%, coarse WC: 80-92%, and fine WC: 3-15%; wherein the average particle size of the coarse WC is 2.0-4.0 μm, and the average particle size of the fine WC is 0.1-0.5 μm.

[0009] The hard alloy material provided by the present application uses Ni, Cr and Cu to replace part of Co to jointly build a stable multi-main-element binder phase. Among them, Ni can reduce the cost, effectively stabilize the FCC structure of the binder phase, and improve the wettability and interface matching of WC and the binder phase, thereby improving the toughness and interface bonding force of the material; Cr can form a Cr-rich interface layer in the alloy, enhance the WC / binder phase interface bonding strength, and inhibit the excessive growth of WC grains, thereby ensuring the uniformity and corrosion resistance of the structure; the introduction of Cu can reduce the liquid phase sintering temperature, promote the densification of the alloy, and improve the plasticity and toughness and the strength-toughness matching ability. Therefore, the synergistic effect of Ni, Cr and Cu is crucial for building a stable multi-main-element binder phase. In addition, the rare earth element Sm is introduced into the alloy system, which can be stably enriched at the interface between WC and the binder phase, effectively inhibit the FCC→HCP martensitic phase transition in the binder phase, and obtain a stable FCC structure without rapid cooling. At the same time, the Sm element has multiple functions such as grain boundary purification, grain refinement and second phase regulation, effectively improving the problems of insufficient sintering activity and uneven structure of WC powder, thereby further improving the density, strength-toughness and wear resistance of the alloy. For the performance defects of single grain structure, the present application introduces coarse and fine WC in the hard alloy material, the fine-grained WC endows the material with excellent hardness and strength, can effectively inhibit the dislocation movement and crack propagation, and significantly improve the wear resistance; the coarse-grained WC has higher crack propagation energy, which helps to relieve stress concentration and inhibit rapid crack propagation, thereby enhancing the fracture toughness. The synergistic effect of multi-scale WC grains in the bicrystal structure causes the crack to deflect, branch and passivate during propagation, significantly improves the crack propagation resistance, delays failure, and improves the toughness and fatigue life of the material. Under the synergistic effect of the above components, the hard alloy material of the present application realizes the synergistic improvement of hardness, strength and toughness.

[0010] Preferably, the cemented carbide material is composed of Co: 2.4-2.5%, Ni: 2.4-2.5%, Cr: 0.4-0.5%, Cu: 0.3-0.4%, Sm: 0.1-0.5%, coarse WC: 84-89%, fine WC: 5-10% by mass.

[0011] Preferably, the cemented carbide material is composed of WC hard phase, CoNiCrCu binder phase and Sm, wherein the Sm is enriched at the interface between the WC hard phase and the CoNiCrCu binder phase, there is a coherent interface between the WC hard phase and the CoNiCrCu binder phase, the CoNiCrCu binder phase is of face-centered cubic (FCC) structure, and the WC hard phase is of twin distribution.

[0012] Preferably, the cemented carbide material has a hardness of 90-91 HRA, a bending strength of 3000-3500 MPa, and a fracture toughness of 13-14 MPa·m 1 / 2 .

[0013] The application also provides a preparation method of the cemented carbide material with high strength and high toughness, which comprises the following steps: preparing CoNiCu-Sm2O3 composite powder by chemical synthesis, obtaining cemented carbide raw powder by mixing CoNiCu-Sm2O3 composite powder, tungsten carbide powder A, tungsten carbide powder B and chromium powder according to a designed proportion, obtaining mixed particles by wet ball milling and drying the cemented carbide raw powder in sequence, obtaining a compact by pressing the mixed particles, obtaining the cemented carbide material by degreasing and sintering the compact.

[0014] The preparation method of the present application first prepares CoNiCu-Sm2O3 by chemical synthesis, compared with the traditional method of directly mixing single element powder, the method can realize the uniform dispersion of each component on the microscale, obtain alloy powder with small particle size and narrow distribution, effectively solve the problem of uneven distribution of trace Cu and trace rare earth elements in the traditional method, and avoid the performance degradation of the alloy caused by composition segregation. It should be emphasized that in this system, the rare earth element does not necessarily exist in the metallic state, and the rare earth oxide itself can play a role in grain boundary purification, refinement and phase stabilization at the WC / binder phase interface, thereby realizing the strengthening effect. The present application selects Sm2O3 as the rare earth source, on the one hand because of its good thermal stability and dispersibility, it can be more stably embedded in the interface, on the other hand it can also avoid the risk of powder agglomeration and inclusion caused by complex reduction process, so it shows better process adaptability and comprehensive effect among many rare earth oxides. As for the adding method of Cr, it is different from Co, Ni and Cu. If introduced in the form of oxides such as Cr2O3, due to its high reduction temperature, it is difficult to completely convert, and high temperature may cause powder agglomeration and form oxide inclusions, reducing the density of the structure and the interface bonding strength. Therefore, the present application adopts metal Cr powder directly added to ensure the effective solid solution of Cr in the binder phase and the interface effect, and avoid the adverse effects of powder agglomeration.

[0015] In the preferred scheme, the process for preparing CoNiCu-Sm2O3 composite powder by chemical synthesis is as follows: adding cobalt source, nickel source, copper source and samarium source into water to obtain a mixed precursor solution, spray drying the mixed precursor solution to obtain an oxide mixed powder, and then reducing the oxide mixed powder in a hydrogen atmosphere in two steps to obtain the CoNiCu-Sm2O3 composite powder. In the first step of reduction, the temperature is controlled at 400-500 DEG C and the time is 60-180 min. In the second step of reduction, the temperature is controlled at 700-800 DEG C and the time is 60-180 min.

[0016] In the present application, chemical synthesis is adopted, first, each soluble raw material is added into deionized water, and fully stirred to form a uniform mixed precursor solution, then spray drying technology is used to rapidly pyrolyze the precursor solution to prepare an oxide mixed powder with uniform morphology, and finally CoNiCu-Sm2O3 composite powder is prepared by two-step reduction. In the first step of reduction, the organic residues and volatile components in the oxide precursor are decomposed, and the oxides with low valence and easy reduction (copper oxide) are preferentially reduced, so as to avoid powder agglomeration or particle breakage caused by gas concentrated release at high temperature; the second step of reduction is used to completely reduce the difficult-to-reduce components (such as CoO, part of NiO). Through step-by-step reduction, not only the uniformity and dispersity of the powder are ensured, but also the problems of agglomeration and segregation caused by one-time high-temperature reduction are effectively avoided.

[0017] Further preferably, the cobalt source is selected from cobalt nitrate (Co(NO3)2), the nickel source is selected from nickel nitrate (Ni(NO3)2), the copper source is selected from copper nitrate (Cu(NO3)2), and the samarium source is selected from samarium sulfate (Sm2(SO4)3).

[0018] Preferably, the average particle size of the tungsten carbide powder A is 2.0-4.0 μm, and the average particle size of the tungsten carbide powder B is 0.1-0.5 μm.

[0019] Preferably, the average particle size of the chromium powder is 1.0-2.0 μm.

[0020] Preferably, the wet ball milling process is as follows: the cemented carbide raw material powder is added into a molding agent for wet ball milling, the ball milling medium is alcohol, the rotation speed of the wet ball milling is 100-300 r / min, and the wet ball milling time is 24-72 h.

[0021] Further preferably, the molding agent is added in an amount of 1.8-2.5% of the mass of the cemented carbide raw material powder, and the molding agent is selected from polyethylene glycol (PEG) or paraffin.

[0022] Further preferably, the liquid-solid volume-mass ratio of the alcohol to the cemented carbide raw material powder is 200-300 mL / kg.

[0023] Preferably, the dry granulation process is as follows: the wet milling slurry obtained by wet ball milling is subjected to drying treatment, and the powder after drying is sieved through a screen mesh to obtain the mixed particles. The mixed particles obtained after sieving have uniform particle size.

[0024] Further preferably, the drying temperature is 60-90 ℃, and the drying time is 5-20 h.

[0025] In actual operation, a high-energy planetary ball mill is used for ball milling, and a vacuum drying box is used for drying treatment.

[0026] Preferably, the press forming is selected from one of cold isostatic pressing, unidirectional pressing, and bidirectional pressing, and the pressure of the press forming is 20-100 MPa.

[0027] Preferably, the debinding is performed in a hydrogen atmosphere, and the debinding temperature is 250-500 ℃.

[0028] Preferably, the sintering is performed in a protective atmosphere, the sintering temperature is 1350-1480 ℃, the sintering time is 60-120 min, and the sintering pressure is controlled to be 5-10 MPa.

[0029] Further preferably, the protective atmosphere is an argon atmosphere.

[0030] By low-pressure sintering densification in an argon atmosphere, the cemented carbide material is obtained after cooling to room temperature.

[0031] The application also provides a use of the high-strength and high-toughness cemented carbide material.

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] The application adopts a chemical synthesis method to prepare mixed powder CoNiCu-Sm2O3 of a binder phase and rare earth oxides. Compared with a traditional direct mixing method of elemental powders, the method can realize uniform dispersion of components at a microscale, obtain alloy powder with small particle size and narrow distribution, effectively solve the problems of uneven distribution and easy segregation of trace Cu and trace rare earth elements in the traditional method, and thus avoid performance degradation of the alloy caused by component segregation. Meanwhile, the process is mild and controllable, has good batch stability and industrial amplification potential, and provides an efficient and feasible technical path for integration of the binder phase and rare earth elements in high-performance cemented carbide.

[0034] The application designs and matches WC with specific particle sizes and specific proportions to construct a stable bicrystal structure. Fine-grained WC endows the material with excellent hardness and strength, can effectively inhibit dislocation movement and crack propagation, and significantly improve wear resistance. Coarse-grained WC has higher crack propagation energy, which helps to relieve stress concentration and inhibit rapid crack propagation, thereby enhancing fracture toughness. The synergistic effect of multi-scale WC grains in the bicrystal structure causes crack deflection, branching and passivation during propagation, significantly improves crack propagation resistance, delays failure, and improves the toughness and fatigue life of the material. The structure realizes the coordination and unity of high strength, high toughness and high hardness.

[0035] The application adopts CoNiCrCu multi-main element alloy to replace the traditional Co single metal as the binder phase. The multi-main element binder phase forms a stable face-centered cubic (FCC) structure, significantly improves the strength and toughness matching ability of the material. At the same time, a stable coherent interface structure is formed between the WC and the multi-main element binder phase interface, significantly enhancing the interface bonding strength, thereby constructing a multi-main element binder phase cemented carbide with high strength, high toughness and structural stability. The material effectively relieves the defects of insufficient toughness and easy brittle fracture of the traditional WC-Co alloy in high impact and high wear service environment, and improves the use reliability of the down-the-hole drill bit in complex rock layers.

[0036] In addition, the present application introduces rare earth element Sm in the alloy system, which can be enriched at the interface of WC and binder phase, effectively inhibits the martensitic phase transition of FCC→HCP in the binder phase, and can obtain stable FCC structure without rapid cooling. At the same time, Sm element has multiple functions such as grain boundary purification, grain refinement and second phase regulation, effectively improves the problems of insufficient sintering activity and uneven organization of WC powder, so as to further improve the density, strength and toughness of the alloy.

[0037] The present application realizes the synergistic improvement of hardness, strength and toughness by scientifically and reasonably designing the composition of multi-main element binder phase, double crystal structure, rare earth additive and optimizing the chemical synthesis process, and the hardness of the obtained hard alloy material is 90-91 HRA, the bending strength is 3000-3500 MPa, and the fracture toughness is 13-14 MPa·m 1 / 2 . BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] Figure 1 is the microstructure diagram of the hard alloy material for a roof drill in Example 1.

[0040] Figure 2 is the microstructure diagram of the hard alloy material for a roof drill in Example 2. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0042] Example 1

[0043] In an alternative embodiment, the present embodiment provides a hard alloy material for a roof drill, which is composed of the following alloy components in weight percentage: Co: 2.5%, Ni: 2.4%, Cr: 0.5%, Cu: 0.4%, Sm: 0.2%, medium-grained WC: 89%, and ultra-fine WC: 5%. The average particle sizes of the two kinds of WC powder are 3.5 μm and 0.2 μm respectively, and the average particle size of the Cr powder is 1.0 μm.

[0044] The preparation method of the hard alloy material for a rock drill comprises the following steps:

[0045] Step S1, preparation of a precursor solution: cobalt nitrate (Co(NO3)2), nickel nitrate (Ni(NO3)2), copper nitrate (Cu(NO3)2) and samarium sulfate (Sm2(SO4)3) are dissolved in deionized water at a predetermined ratio, and fully stirred to form a uniform mixed precursor solution.

[0046] Step S2, spray drying: the precursor solution is rapidly pyrolyzed by using a spray drying technique to obtain an oxide mixed powder with uniform morphology.

[0047] Step S3, two-step reduction: first, a first reduction treatment is performed at 450°C in a hydrogen atmosphere for 120 min; then, a second reduction is performed at 750°C in a hydrogen environment for 120 min, and finally a CoNiCu-Sm2O3 composite powder with uniform composition is obtained.

[0048] Step S4, ball milling mixing: tungsten carbide powder, chromium powder and CoNiCu-Sm2O3 powder of two particle sizes are mixed according to a predetermined mass percentage, and after adding an appropriate amount of a forming agent, wet ball milling is performed to ensure that the components are fully mixed, and a uniform wet abrasive slurry is obtained; the forming agent is PEG, and the addition amount of PEG is 2% of the weight of the hard alloy powder; the wet milling process parameters are: the ball milling medium is alcohol, the liquid-solid ratio of alcohol to raw materials is 235 mL / kg, the ball milling speed is 150 r / min, and the ball milling time is 36 h.

[0049] Step S5, drying and granulation: the obtained wet abrasive slurry is placed in a vacuum drying box for drying treatment, and the dried powder is sieved to obtain an alloy powder with uniform particle size; the drying temperature is 60°C, and the drying time is 20 h.

[0050] Step S6, pressing forming: the sieved powder is pressed and formed to obtain a semi-finished blank with the expected morphology and initial density; the pressing mode is unidirectional pressing, and the pressing pressure is 50 MPa.

[0051] Step S7, debinding and sintering: the semi-finished product is subjected to debinding treatment in a hydrogen atmosphere, the debinding treatment temperature is 450°C, the debinding treatment time is 600 min, and then the sintering process is completed in an argon atmosphere, and finally a hard alloy finished product with dense structure and excellent performance is obtained; the argon pressure is 6 MPa, the sintering temperature is 1450°C, and the holding time is 90 min.

[0052] The performance test results of the hard alloy material for a rock drill of the embodiment are shown in Table 1; the scanning electron microscope photos are as follows: Figure 1as shown.

[0053] Embodiment 2

[0054] In yet another optional embodiment, the present embodiment provides a cemented carbide material for rock drill, which is composed of the following alloy components in weight percentage: Co: 2.4%, Ni: 2.4%, Cr: 0.4%, Cu: 0.3%, Sm: 0.3%, medium-grained WC: 86.2%, and ultra-fine WC: 8%. The average particle size of the two kinds of WC powder is 3.5 μm and 0.2 μm, and the average particle size of the Cr powder is 1.0 μm.

[0055] The preparation method of the cemented carbide material for rock drill described above comprises the following steps:

[0056] Step S1, preparation of precursor solution: dissolve cobalt nitrate (Co(NO3)2), nickel nitrate (Ni(NO3)2), copper nitrate (Cu(NO3)2), and samarium sulfate (Sm2(SO4)3) in deionized water in a predetermined ratio, and fully stir to form a uniform mixed precursor solution.

[0057] Step S2, spray drying: use spray drying technology to rapidly pyrolyze the precursor solution to obtain oxide mixed powder with uniform morphology.

[0058] Step S3, two-step reduction: first, perform the first reduction treatment at 500°C in a hydrogen atmosphere for 150 min; then, perform the second reduction in a hydrogen environment at 760°C for 150 min, to finally obtain CoNiCu-Sm2O3 composite powder with uniform composition.

[0059] Step S4, ball milling mixing: mix the two kinds of tungsten carbide powder, chromium powder, and CoNiCu-Sm2O3 powder in a predetermined mass percentage, add an appropriate amount of forming agent, and then perform wet ball milling to ensure that the components are fully mixed, and obtain a uniform wet abrasive slurry; the forming agent is PEG, and the addition amount of PEG is 2% of the weight of the cemented carbide powder; the wet milling process parameters are: the ball milling medium is alcohol, the liquid-solid ratio of alcohol to raw materials is 220 mL / kg, the ball milling speed is 180 r / min, and the ball milling time is 48 h.

[0060] Step S5, drying and granulation: place the obtained wet abrasive slurry in a vacuum drying box for drying treatment, screen the dried powder through a screen to obtain alloy powder with uniform particle size; the drying temperature is 60°C, and the drying time is 18 h.

[0061] Step S6, press forming: perform press forming on the screened powder to obtain a semi-finished blank with the expected morphology and initial density; the press forming method is unidirectional pressing, and the pressing pressure is 60 MPa.

[0062] Step S7, debinding sintering: the semi-finished product is subjected to debinding treatment in a hydrogen atmosphere, the temperature of the debinding treatment is 450 ℃, the time of the debinding treatment is 550 min, and then the sintering process is completed in an argon atmosphere, finally a hard alloy finished product with dense structure and excellent performance is obtained; the argon pressure is 6 MPa, the sintering temperature is 1450 ℃, and the holding time is 90 min.

[0063] The performance test results of the hard alloy material for rock drill of the embodiment are shown in Table 1; the scanning electron microscope photos are as shown in Figure 2

[0064] Embodiment 3

[0065] In another optional embodiment, the embodiment provides a hard alloy material for rock drill, which is composed of the following alloy components in percentage by weight: Co: 2.5%, Ni: 2.5%, Cr: 0.4%, Cu: 0.3%, Sm: 0.4%, medium-grained WC: 87.9%, and ultra-fine WC: 6%. The average particle diameter of the two kinds of WC powder is 3.5 μm and 0.2 μm, and the average particle diameter of the Cr powder is 1.0 μm.

[0066] The preparation method of the hard alloy material for rock drill, comprising the following steps:

[0067] Step S1, preparation of precursor solution: dissolve cobalt nitrate (Co(NO3)2), nickel nitrate (Ni(NO3)2), copper nitrate (Cu(NO3)2), and samarium sulfate (Sm2(SO4)3) in deionized water according to the preset ratio, and fully stir to form a uniform mixed precursor solution.

[0068] Step S2, spray drying: use spray drying technology to rapidly pyrolyze the precursor solution to obtain oxide mixed powder with uniform morphology.

[0069] Step S3, two-step reduction: first, perform the first reduction treatment in a hydrogen atmosphere at 450 ℃ for 160 min; then, perform the second reduction in a hydrogen environment at 800 ℃ for 160 min, finally obtain CoNiCu-Sm2O3 composite powder with uniform composition.

[0070] Step S4, ball milling mixing: mix the two kinds of tungsten carbide powder, chromium powder, and CoNiCu-Sm2O3 powder according to the predetermined mass percentage, add an appropriate amount of forming agent, and then perform wet ball milling to ensure that the components are fully mixed, and obtain a uniform wet abrasive slurry; the wet milling process parameters are: the ball milling medium is alcohol, the liquid-solid ratio of alcohol to raw materials is 210 mL / kg, the ball milling speed is 160 r / min, and the ball milling time is 40 h.

[0071] ​Step S5, dry granulation: the obtained wet milling slurry is placed in a vacuum drying oven for drying treatment, and the dried powder is sieved through a screen to obtain alloy powder with uniform particle size; the drying temperature is 70°C, and the drying time is 10h.

[0072] Step S6, compression molding: the sieved powder is subjected to compression molding to obtain a semi-finished product blank with a desired morphology and initial density; the compression molding method is unidirectional compression, and the compression pressure is 55 MPa.

[0073] Step S7, debinding and sintering: the semi-finished product is subjected to debinding treatment in a hydrogen atmosphere, the debinding treatment temperature is 460°C, the debinding treatment time is 600 min, and then sintering is completed in an argon atmosphere to obtain a hard alloy finished product with a dense structure and excellent performance; the argon pressure is 6 MPa, the sintering temperature is 1430°C, and the holding time is 90 min.

[0074] Comparative Example 1

[0075] The present comparative example provides a hard alloy material for a down-the-hole drill, which is composed of the following alloy components by weight percentage: Co: 6%, medium particle WC: 94%. The average particle size of the WC powder is 3.5 μm, and the average particle size of the Co powder is 1.5 μm.

[0076] The preparation method of the above-mentioned hard alloy material for a down-the-hole drill comprises the following steps:

[0077] Step S1, ball milling: the tungsten carbide powder and cobalt powder are prepared according to the predetermined mass percentage, and then wet ball milling is performed after adding an appropriate amount of forming agent to ensure that the components are fully mixed to obtain a uniform wet milling slurry; the wet milling process parameters are as follows: the ball milling medium is alcohol, the liquid-solid ratio of alcohol to raw materials is 210 mL / kg, the ball milling speed is 160 r / min, and the ball milling time is 40 h.

[0078] Step S2, dry granulation: the obtained wet milling slurry is placed in a vacuum drying oven for drying treatment, and the dried powder is sieved through a screen to obtain alloy powder with uniform particle size; the drying temperature is 70°C, and the drying time is 10h.

[0079] Step S3, compression molding: the sieved powder is subjected to compression molding to obtain a semi-finished product blank with a desired morphology and initial density; the compression molding method is unidirectional compression, and the compression pressure is 55 MPa.

[0080] Step S4, debinding sintering: the semi-finished product is subjected to debinding treatment in a hydrogen atmosphere, the debinding treatment temperature is 460 DEG C, the debinding treatment time is 600 min, and then the sintering process is completed in an argon atmosphere, finally a hard alloy finished product with dense structure and excellent performance is obtained; the argon pressure is 6 MPa, the sintering temperature is 1430 DEG C, and the holding time is 90 min.

[0081] Comparative Example 2

[0082] The present comparative example provides a hard alloy material for rock drill, which is composed of the following alloy components by weight percentage: Co: 2.8%, Ni: 2.5%, Cr: 0.4%, Cu: 0.3%, medium-grained WC: 94%. The average particle size of the WC powder is 3.5 μm, the average particle size of the Co powder is 1.5 μm, the average particle size of the Ni powder is 2.0 μm, the average particle size of the Cr powder is 1.0 μm, and the average particle size of the Cu powder is 1.5 μm.

[0083] The preparation method of the above-mentioned hard alloy material for rock drill comprises the following steps:

[0084] Step S1, ball milling mixing: the tungsten carbide powder, cobalt powder, nickel powder, chromium powder and copper powder are proportioned according to the predetermined mass percentage, and then wet ball milling is carried out after adding an appropriate amount of forming agent to ensure that the components are fully mixed to obtain a uniform wet milling slurry; the wet milling process parameters are as follows: the ball milling medium is alcohol, the liquid-solid ratio of alcohol to raw materials is 210 mL / kg, the ball milling speed is 160 r / min, and the ball milling time is 40 h.

[0085] Step S2, drying and granulation: the obtained wet milling slurry is placed in a vacuum drying box for drying treatment, and the dried powder is sieved through a screen to obtain alloy powder with uniform particle size; the drying temperature is 70 DEG C, and the drying time is 10 h.

[0086] Step S3, pressing forming: the sieved powder is subjected to pressing forming to obtain a semi-finished product blank with the expected morphology and initial density; the pressing method is unidirectional pressing, and the pressing pressure is 55 MPa.

[0087] Step S4, debinding sintering: the semi-finished product is subjected to debinding treatment in a hydrogen atmosphere, the debinding treatment temperature is 460 DEG C, the debinding treatment time is 600 min, and then the sintering process is completed in an argon atmosphere, finally a hard alloy finished product with dense structure and excellent performance is obtained; the argon pressure is 6 MPa, the sintering temperature is 1430 DEG C, and the holding time is 90 min.

[0088] The performance test results of the hard alloy material for rock drill of the present example and comparative examples are shown in Table 1.

[0089]

[0090] Each of the embodiments in the specification is described in a relevant manner, and the same or similar parts between the embodiments can be referred to each other. Each of the embodiments focuses on the difference from other embodiments. In particular, for the system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the method embodiments.

[0091] The above only describes the preferred embodiments of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-strength high-toughness cemented carbide material, characterized in that: The hard alloy material is composed of Co: 2-3%, Ni: 2-3%, Cr: 0.2-1%, Cu: 0.2-1%, Sm: 0.1-1%, coarse WC: 80-92%, fine WC: 3-15% by mass percentage.

2. The high strength and toughness cemented carbide material according to claim 1, characterized in that: The hard alloy material is composed of WC hard phase, CoNiCrCu binder phase and Sm, wherein the Sm is enriched at the interface of the WC hard phase and the CoNiCrCu binder phase, a coherent interface exists between the WC hard phase and the CoNiCrCu binder phase, and the CoNiCrCu binder phase is of FCC structure; and the WC hard phase presents a twin distribution.

3. The high-strength and high-toughness cemented carbide material according to claim 1 or 2, characterized in that: The hardness of the cemented carbide material is 90-91 HRA, the bending strength is 3000-3500 MPa, and the fracture toughness is 13-14 MPa·m 1 / 2 .

4. The method of producing a high-strength and high-toughness cemented carbide material according to any one of claims 1 to 3, characterized in that: First, CoNiCu-Sm2O3 composite powder is prepared by a chemical synthesis method, hard alloy raw material powder is obtained by mixing CoNiCu-Sm2O3 composite powder, tungsten carbide powder A, tungsten carbide powder B and chromium powder according to a designed proportion, and then the hard alloy raw material powder is sequentially subjected to wet ball milling, drying and granulation to obtain mixed particles, the mixed particles are pressed to form a green compact, the green compact is subjected to debinding and sintering to obtain the hard alloy material.

5. The method according to claim 4, wherein the high strength and toughness cemented carbide material is prepared by the following steps: The process for preparing the CoNiCu-Sm2O3 composite powder by the chemical synthesis method comprises the following steps: adding a cobalt source, a nickel source, a copper source and a samarium source into water to obtain a mixed precursor solution, performing spray drying on the mixed precursor solution to obtain an oxide mixed powder, and then performing two-step reduction on the oxide mixed powder in a hydrogen atmosphere, wherein the temperature is controlled to be 400-500 DEG C and the time is controlled to be 60-180 min in the first step, and the temperature is controlled to be 700-800 DEG C and the time is controlled to be 60-180 min in the second step. ​ The cobalt source is selected from cobalt nitrate, the nickel source is selected from nickel nitrate, the copper source is selected from copper nitrate, and the samarium source is selected from samarium sulfate.

6. The method according to claim 4, wherein the high strength and toughness cemented carbide material is prepared by the following steps: The average particle size of the tungsten carbide powder A is 2.0-4.0 μm, and the average particle size of the tungsten carbide powder B is 0.1-0.5 μm. ​ The average particle size of the chromium powder is 1.0-2.0 μm.

7. The method according to claim 4, wherein the high strength and toughness cemented carbide material is prepared by the following steps: The process for the wet ball milling comprises the following steps: adding the hard alloy raw material powder into a forming agent to perform wet ball milling, the ball milling medium is alcohol, the rotation speed of the wet ball milling is 100-300 r / min, and the time of the wet ball milling is 24-72 h. ​ The adding amount of the forming agent is 1.8-2.5% of the mass of the hard alloy raw material powder, and the forming agent is selected from polyethylene glycol or paraffin wax. The liquid-solid volume-mass ratio of the alcohol to the hard alloy raw material powder is 200-300 mL / kg.

8. The method according to claim 4, wherein the high strength and toughness cemented carbide material is prepared by the following steps: The process for the drying and granulation comprises the following steps: performing drying treatment on the wet milling slurry obtained by the wet ball milling, and then performing screen separation on the powder after drying to obtain the mixed particles. ​ The temperature for the drying is 60-90 DEG C, and the time for the drying is 5-20 h. The pressure for the pressing forming is 20-100 MPa.

9. The method according to claim 4, wherein the high strength and toughness cemented carbide material is prepared by the following steps: The debinding is performed in a hydrogen atmosphere, and the temperature for the debinding is 250-500 DEG C. ​ The sintering is carried out under a protective atmosphere, the sintering temperature is 1350-1480 DEG C, the sintering time is 60-120 min, and the control pressure is 5-10 MPa during sintering.

10. Use of a high-strength, high-toughness cemented carbide material according to any one of claims 1-3, characterised in that: The cemented carbide material is used for down-the-hole drilling.

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