A high-strength and high-toughness cemented carbide material and its preparation method

Abstract

The present invention relates to a high-strength and high-toughness cemented carbide material and a preparation method thereof, belonging to the technical field of alloy material preparation. The cemented carbide material specifically comprises the following raw materials by weight: 75-80 parts of WC, 5-8 parts of TiC, 10-12 parts of Co-Ni alloy, 0.5-1 parts of rare earth oxide, 11-15 parts of interface optimization material, and 0.1-0.15 parts of graphene-carbon nanotube hybrid material; wherein the rare earth oxide is Y2O3; and the interface optimization material is obtained by mixing a high-entropy alloy, a boride, and a carbonitride. By compounding the high-entropy alloy, boride, and carbonitride to construct a gradient interface, combining the grain boundary pinning effect of the graphene-CNT hybrid material, and a deep cold-aging synergistic process, the material overcomes the strength-toughness contradiction of traditional cemented carbide and provides an innovative solution for high-end equipment manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy material preparation, and more particularly to a high-strength and high-toughness hard alloy material and a preparation method thereof. Background Art

[0002] As the "teeth" of modern industry, cemented carbide is widely used in cutting tools, mining machinery, aerospace, and other fields. The core of its performance lies in the synergistic effect of the hard phase and the binder phase. However, traditional cemented carbide faces significant bottlenecks in strengthening and toughening: on the one hand, WC grain coarsening leads to increased crack sensitivity, while excessive addition of grain inhibitors such as VC and Cr3C2, while refining the grains, sacrifices toughness. On the other hand, the traditional binder phase Co easily softens at high temperatures, is scarce in resources, and is costly. Alternative binder phases Ni or Fe lack oxidation resistance and wettability, resulting in weak interfacial bonding and limited service life.

[0003] In recent years, high-entropy alloys (HEAs) have been introduced into the cemented carbide field due to their unique lattice distortion and "cocktail effect." Research has shown that HEAs, such as AlCoCrFeNi, can refine WC grains to submicron levels as a binder phase while enhancing interfacial bonding strength through the formation of reinforcing phases such as Ni3Al. However, existing HEA systems are limited, and their application in alloy preparation requires a more robust thermal stress buffering process, which can easily lead to interfacial oxidation cracking and phase segregation.

[0004] To address the above problems, there is an urgent need to develop a cemented carbide system that combines ultrafine grains, interface toughening and process controllability. Summary of the Invention

[0005] In order to solve the problems raised in the background technology, the present invention provides a high-strength and high-toughness cemented carbide material and a preparation method thereof.

[0006] The present invention provides a high-strength and high-toughness cemented carbide material and a preparation method thereof, which adopts the following technical solutions:

[0007] A high-strength and high-toughness cemented carbide material, comprising the following raw materials in parts by weight:

[0008] 75-80 parts of WC, 5-8 parts of TiC, 10-12 parts of Co-Ni alloy, 0.5-1 parts of rare earth oxide, 11-15 parts of interface optimization material and 0.1-0.15 parts of graphene-carbon nanotube hybrid material;

[0009] The interface optimization material is obtained by mixing high entropy alloy, boride and carbonitride.

[0010] In the above technical solution, WC and TiC are used as hard phases in the alloy material, WC provides high hardness, TiC enhances wear resistance and impact resistance; Co-Ni alloy is used as tough phase, rare earth oxides inhibit abnormal growth of WC grains, and Y 3+ Occupying grain boundaries reduces interfacial energy, and compounding carbon nanotube hybrid material components further reduces grain coarsening during sintering densification, inhibiting crack propagation by refining grains.

[0011] Furthermore, the rare earth oxide is Y2O3.

[0012] Furthermore, the high entropy alloy in the interface optimization material is at least one of AlCoCrFeNi, AlCoCrFeNi, and MoTaVW. Preferably, the high entropy alloy in the interface optimization material is AlCoCrFeNi.

[0013] Furthermore, the boride is at least one of FeB, CrB2, and TiB2. Preferably, the boride is TiB2.

[0014] Furthermore, the carbonitride is TiCN and / or C3N4.

[0015] Furthermore, the interface optimization material is obtained by mixing high entropy alloy, boride and carbonitride in a mass ratio of (8-10):(2-3):(1-2).

[0016] Furthermore, the graphene-carbon nanotube hybrid material is prepared by the following steps:

[0017] A1. Mixing multi-walled carbon nanotubes with a sulfuric acid solution, ultrasonically mixing for 20-30 minutes, then filtering and washing the precipitate with deionized water until the pH value of the washing solution is neutral to obtain pretreated carbon nanotubes;

[0018] A2, immersing the pretreated carbon nanotubes in a PdCl2 solution, ultrasonically treating for 5-10 minutes, and then electrolessly plating nickel for 20-30 minutes, followed by filtering, washing, and drying to obtain Ni-coated CNTs;

[0019] A3. Heat the Ni-coated CNT to 800-820°C under the protection of Ar / H2 mixed gas, keep warm for 20-30 minutes, then introduce CH4 and H2, keep warm at 800-820°C for 1-1.5 hours, and then cool to room temperature to obtain a graphene-carbon nanotube hybrid material.

[0020] Furthermore, the graphene-carbon nanotube hybrid material is prepared by the following steps:

[0021] A1. Mix multi-walled carbon nanotubes with 6 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g:10 mL, ultrasonically mix for 20-30 min, then filter and wash the precipitate with deionized water until the pH value of the washing solution is neutral to obtain pretreated carbon nanotubes;

[0022] A2: Immerse the pretreated carbon nanotubes in a PdCl2 solution with a pH value of 5 and a concentration of 0.1 mol / L at a solid-liquid ratio of 1 g:10 mL. Ultrasonic treatment is performed for 5-10 min before chemical nickel plating. Ammonia water is used to adjust the pH value of the plating solution to 8.5. The current density is 2 A / dm 2 , the electroplating time is 20-30 min, followed by filtration and washing with ethanol solution, and drying at 60 ° C to obtain Ni-coated CNT;

[0023] A3. Under the protection of Ar / H2 mixed gas, heat the Ni-coated CNT to 800-820℃ at 10℃ / min, keep it warm for 20-30min, then introduce CH4 and H2, keep it warm at 800-820℃ for 1-1.5h, and then cool it to room temperature at 5-10℃ / min to obtain graphene-carbon nanotube hybrid material.

[0024] In the above reaction process, the graphene-carbon nanotube hybrid material is prepared by in-situ chemical vapor deposition. Specifically, the multi-walled carbon nanotubes are first washed and then Ni nanoparticles are deposited on their surface. The Ni nanoparticles on the multi-walled carbon nanotubes act as a catalyst. Subsequently, methane is cracked by vapor phase chemical deposition and Ni catalysis to generate carbon atoms that are deposited on the CNT surface to form few-layer graphene. Graphene is then deposited on the carbon nanotubes to obtain a graphene-carbon nanotube hybrid material.

[0025] Furthermore, in step A2, the electroplating solution uses water as a solvent and includes the following components: 0.1 mol / L NiSO4, 0.5 mol / L H2SO4, 0.2 mol / L sodium hypophosphite and 0.01 wt% thiourea.

[0026] Preferably, in step A3, the volume ratio of Ar to H2 in the Ar / H2 mixed gas is 95:5, and the flow rate of the mixed gas is 40-50 sccm.

[0027] Furthermore, in step A3, the gas flow rate of CH4 is 45-55 sccm, and the gas flow rate of H2 is 15-25 sccm.

[0028] A method for preparing a high-strength and high-toughness cemented carbide material comprises the following steps:

[0029] S1. Pre-alloying of raw materials: Weigh the raw materials in the formula and perform ball milling. After drying the ball milled product, pre-sinter it at 900-1000°C for 1.5-2h under inert atmosphere to obtain a pre-sintered green body;

[0030] S2, cold isostatic pressing: the pre-sintered green body obtained in step S1 is pressed at a pressure of 200-250 MPa and a holding time of 5-7 min to obtain a formed green body;

[0031] S3, sintering cryogenic treatment:

[0032] The formed green body obtained in step S2 is heated to 600-650°C at a heating rate of 5-10°C / min under an inert atmosphere and then hot-pressed and sintered. The pressing pressure is set to 1-50 MPa.

[0033] Then continue to increase the temperature to 1400-1450℃ at a heating rate of 1-5℃ / min, set the pressure to 18-20Mpa, and keep warm for 1-1.5h to carry out the second step of sintering treatment;

[0034] The system is then transferred to a liquid nitrogen environment for 3-4 hours and then naturally restored to room temperature for cryogenic treatment; the system temperature is further increased at 5-10°C / min to 1600-1750°C for vacuum sintering, and kept at this temperature for 30-45 minutes for the third sintering step.

[0035] S4, step-by-step aging treatment: the green body obtained in step S3 is naturally cooled to 600-620°C in the furnace and aged for 1.5-2 hours; then cooled to 300-320°C at a rate of 10-20°C / min in a vacuum environment and aged for 1-1.5 hours to obtain a high-strength and high-toughness cemented carbide material.

[0036] During the above preparation process, various forming and sintering treatments are used to enable the high-entropy alloy to hinder dislocation movement through the lattice distortion effect, while the precipitated strengthening phases such as Ni3Al enhance the interface bonding strength; borides and carbonitrides act as gradient strengthening layers to form a gradient interface, reduce thermal stress concentration, enhance interface bonding strength, and inhibit interface oxidation and crack initiation.

[0037] Cryogenic treatment induces the dispersed precipitation of η phase (Co6W6C) within the WC hard phase, while simultaneously promoting the precipitation of body-centered cubic phases such as α-Fe in the high-entropy alloy, forming a multiscale strengthening network. Aging treatment optimizes the size of the precipitated phases, preventing strength loss due to coarsening. Low-temperature aging stabilizes the interfacial structure, inhibiting performance degradation over long-term service. The synergistic effects of cryogenic and aging treatments further enhance the simultaneous optimization of strength, toughness, and wear resistance.

[0038] Furthermore, in step S1, the specific parameters of the ball milling treatment are: ball-to-material ratio of 4-5:1, ball milling speed of 300-400 rm, and ball milling time of 20-30 h.

[0039] Furthermore, in step S3, the pressure of hot pressing sintering is 40-50 MPa.

[0040] In summary, the present invention has the following beneficial effects:

[0041] 1. In the technical solution of the present invention, a combination of high-entropy alloy, boride, and carbonitride is used as the interface optimization material. The lattice distortion effect of the high-entropy alloy is used to hinder dislocation motion. During the sintering process, Ni3Al and other reinforcing phases are formed, which are beneficial to interface bonding. The boride can form a gradient strengthening layer at the interface with WC, further strengthening the interface bonding. When combined with the carbonitride, it forms a continuous transition layer at high temperatures, alleviating thermal stress concentration and reducing the formation of interfacial oxidation cracks. When the three are properly combined, they can greatly improve the interface bonding quality and thus enhance the alloy's mechanical properties such as wear resistance and strength.

[0042] 2. In the technical solution of the present invention, the performance of the alloy is optimized by preparing a graphene-carbon nanotube hybrid material. The tubular structure of the CNTs is embedded in the WC grain boundaries. Combined with the two-dimensional surface of the graphene, it forms a three-dimensional barrier network, which inhibits WC grain coarsening through grain boundary pinning. Compared with commercially available hybrid materials, the resulting product does not require multiple steps such as pickling and etching to deal with the problem of subsequent metal catalyst impurities. The Ni coating is completely integrated with the Co-Ni alloy during the subsequent sintering process. While saving costs, the metallic Ni catalyst also accelerates heat and mass transfer of the hybrid material during the sintering process, which helps improve the performance of the resulting alloy product.

[0043] 3. In the technical solution of the present invention, a cryogenic treatment is provided in the middle of the gradient heat treatment process, and an aging treatment is provided at the end. Through the first sintering, the grain boundary sliding in the early stage of densification is promoted, the porosity is reduced, and the hybrid material is pre-sintered to avoid cracking caused by thermal stress. The secondary sintering eliminates the residual pores and achieves full densification. Subsequently, the cryogenic treatment is followed by a third sintering. The cryogenic treatment promotes the diffusion of interface elements, promotes the precipitation of the nano-scale Co3W3C phase inside the WC and the α-Fe phase in the high entropy alloy, and promotes the formation of a "hard phase + tough phase" gradient structure. At the same time, it inhibits carbide segregation and uniformity of interface element distribution, improves the strength and toughness of the alloy material, and then performs a third sintering to strengthen the alloy network. Finally, the step-by-step aging is performed to suppress the coarsening of the phase to reduce the fluctuation of hardness and improve long-term service stability. DETAILED DESCRIPTION

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0045] The materials used in the examples and comparative examples were all chemically pure. The Co-Ni alloy used had an average particle size of 100 μm, an impurity content of 0.01%, and a nickel content of 10%. The carbon nanotubes used had an outer diameter of 30-50 nm and a purity of 98%.

[0046] High-entropy alloy AlCoCrFeNi: particle size 15-53 μm, provided by Beijing Yijin New Materials Technology Co., Ltd.

[0047] Example 1

[0048] A high-strength and high-toughness cemented carbide material, comprising the following raw materials in parts by weight:

[0049] 75 parts of WC, 5 parts of TiC, 10 parts of Co-Ni alloy, 0.5 parts of rare earth oxide, 11 parts of interface optimization material and 0.1 parts of graphene-carbon nanotube hybrid material;

[0050] Wherein, the rare earth oxide is Y2O3;

[0051] The interface optimization material is obtained by mixing a high entropy alloy, a boride, and a carbonitride in a mass ratio of 8:2:1; the high entropy alloy is AlCoCrFeNi, the boride is TiB2, and the carbonitride is TiCN;

[0052] The graphene-carbon nanotube hybrid material is prepared by the following steps:

[0053] A1. Mix multi-walled carbon nanotubes with 6 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g:10 mL, and perform ultrasonic mixing treatment at an ultrasonic power of 200 W and a sonication time of 20 min. Then, filter and wash the precipitate with deionized water until the pH value of the washing solution is neutral to obtain pretreated carbon nanotubes.

[0054] A2: The pretreated carbon nanotubes were immersed in a PdCl2 solution with a pH value of 5 and a concentration of 0.1 mol / L at a solid-liquid ratio of 1 g:10 mL. After ultrasonic treatment for 5 min, chemical nickel plating was performed. The pH value of the plating solution was adjusted to 8.5 with ammonia water and the current density was 2 A / dm 2 The electroplating time was 20 min, followed by filtration and washing with ethanol / water (1:1), and drying at 60 ° C for 15 min to obtain Ni-coated CNTs; the electroplating solution used was water as a solvent and included the following components: 0.1 mol / L NiSO4, 0.5 mol / L H2SO4, 0.2 mol / L sodium hypophosphite and 0.01 wt% thiourea;

[0055] A3. Under the protection of Ar / H2 mixed gas, the Ni-coated CNT was heated to 800°C at a rate of 10°C / min, kept at this temperature for 20 minutes, and then CH4 and H2 were introduced. The mixture was kept at 80°C for 1 hour, and then cooled to room temperature at a rate of 5°C / min to obtain a graphene-carbon nanotube hybrid material; the volume ratio of Ar and H2 was 95:5, the mixed gas flow rate was 40 sccm; the gas flow rate of CH4 was 45 sccm, and the gas flow rate of H2 was 15 sccm.

[0056] The preparation method of the high-strength and high-toughness cemented carbide material comprises the following steps:

[0057] S1. Pre-alloying of raw materials: Weigh the raw materials in the formula and perform ball milling. After drying the ball milled product, pre-sinter it at 1000°C for 2 hours under argon protection to obtain a pre-sintered green body;

[0058] S2, cold isostatic pressing: the pre-sintered green body obtained in step S1 is pressed at a pressure of 200 MPa and a holding time of 5 min to obtain a formed green body;

[0059] S3, sintering cryogenic treatment:

[0060] The formed green body obtained in step S2 was heated to 600°C at a heating rate of 5°C / min under an inert atmosphere and then hot-pressed and sintered. The pressing pressure was set to 20 MPa.

[0061] Then, the temperature was raised to 1400°C at a heating rate of 5°C / min, the pressure was set to 20 MPa, and the temperature was kept at that temperature for 1 hour to carry out the second sintering process;

[0062] The system was then transferred to a liquid nitrogen environment for 4 hours and then the temperature was raised to room temperature at a rate of 5°C / min for cryogenic treatment. The temperature of the system was further raised to 1600°C at a rate of 10°C / min for vacuum sintering and kept at this temperature for 30 minutes for the third sintering treatment.

[0063] S4, step-by-step aging treatment: the green body obtained in step S3 is naturally cooled to 600°C in the furnace and aged for 1.5 hours; then cooled to 300°C at a rate of 20°C / min in a vacuum environment and aged for 1 hour to obtain a high-strength and high-toughness cemented carbide material.

[0064] Example 2

[0065] A high-strength and high-toughness cemented carbide material, comprising the following raw materials in parts by weight:

[0066] 78 parts of WC, 7 parts of TiC, 11 parts of Co-Ni alloy, 0.8 parts of rare earth oxide, 13 parts of interface optimization material and 0.13 parts of graphene-carbon nanotube hybrid material;

[0067] Wherein, the rare earth oxide is Y2O3;

[0068] The interface optimization material is obtained by mixing a high entropy alloy, a boride, and a carbonitride in a mass ratio of 9:3:2; the high entropy alloy is AlCoCrFeNi, the boride is TiB2, and the carbonitride is TiCN;

[0069] The graphene-carbon nanotube hybrid material is prepared by the following steps:

[0070] A1. Mix multi-walled carbon nanotubes with 6 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g:10 mL, and perform ultrasonic mixing treatment at an ultrasonic power of 200 W and a sonication time of 30 min. Then, filter and wash the precipitate with deionized water until the pH value of the washing solution is neutral to obtain pretreated carbon nanotubes.

[0071] A2: The pretreated carbon nanotubes were immersed in a PdCl2 solution with a pH value of 5 and a concentration of 0.1 mol / L at a solid-liquid ratio of 1 g:10 mL. After ultrasonic treatment for 10 min, chemical nickel plating was performed. The pH value of the plating solution was adjusted to 8.5 with ammonia water and the current density was 2 A / dm 2 The electroplating time was 30 min, followed by filtration and washing with ethanol / water (1:1), and drying at 60 ° C for 15 min to obtain Ni-coated CNTs; the electroplating solution used was water as a solvent and included the following components: 0.1 mol / L NiSO4, 0.5 mol / L H2SO4, 0.2 mol / L sodium hypophosphite and 0.01 wt% thiourea;

[0072] A3. Under the protection of Ar / H2 mixed gas, the Ni-coated CNT was heated to 800°C at a rate of 10°C / min, kept at this temperature for 30 minutes, and then CH4 and H2 were introduced. The mixture was kept at 810°C for 1.5 hours and then cooled to room temperature at a rate of 10°C / min to obtain a graphene-carbon nanotube hybrid material; the volume ratio of Ar and H2 was 95:5, the mixed gas flow rate was 50 sccm; the gas flow rate of CH4 was 50 sccm, and the gas flow rate of H2 was 20 sccm.

[0073] The preparation method of the high-strength and high-toughness cemented carbide material comprises the following steps:

[0074] S1. Pre-alloying of raw materials: Weigh the raw materials in the formula and perform ball milling. After drying the ball milled product, pre-sinter it at 1000°C for 2 hours under argon protection to obtain a pre-sintered green body;

[0075] S2, cold isostatic pressing: the pre-sintered green body obtained in step S1 is pressed at a pressure of 230 MPa and a holding time of 5 min to obtain a formed green body;

[0076] S3, sintering cryogenic treatment:

[0077] The formed green body obtained in step S2 was heated to 600°C at a heating rate of 10°C / min under an inert atmosphere and then hot-pressed and sintered. The pressing pressure was set to 30 MPa.

[0078] Then, the temperature was raised to 1400°C at a heating rate of 5°C / min, the pressure was set to 20 MPa, and the temperature was kept at this temperature for 1.5 hours to carry out the second sintering process.

[0079] The system was then transferred to a liquid nitrogen environment for treatment for 4 hours, and then the temperature was raised to room temperature at a rate of 5°C / min for cryogenic treatment; the temperature of the system was further raised to 1700°C at a rate of 10°C / min for vacuum sintering, and kept at this temperature for 40 minutes for the third sintering treatment.

[0080] S4. Stepwise aging treatment: The green body obtained in step S3 is naturally cooled to 610°C in the furnace and aged for 2 hours; then cooled to 310°C at a rate of 20°C / min in a vacuum environment and aged for 1.5 hours to obtain a high-strength and high-toughness cemented carbide material.

[0081] Example 3

[0082] A high-strength and high-toughness cemented carbide material, comprising the following raw materials in parts by weight:

[0083] 80 parts of WC, 8 parts of TiC, 12 parts of Co-Ni alloy, 1 part of rare earth oxide, 15 parts of interface optimization material and 0.15 parts of graphene-carbon nanotube hybrid material;

[0084] Wherein, the rare earth oxide is Y2O3;

[0085] The interface optimization material is obtained by mixing a high entropy alloy, a boride, and a carbonitride in a mass ratio of 10:3:2; the high entropy alloy is AlCoCrFeNi, the boride is CrB2, and the carbonitride is C3N4;

[0086] The graphene-carbon nanotube hybrid material is prepared by the following steps:

[0087] A1. Mix multi-walled carbon nanotubes with 6 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g:10 mL, and perform ultrasonic mixing treatment at an ultrasonic power of 200 W and a sonication time of 30 min. Then, filter and wash the precipitate with deionized water until the pH value of the washing solution is neutral to obtain pretreated carbon nanotubes.

[0088] A2: The pretreated carbon nanotubes were immersed in a PdCl2 solution with a pH value of 5 and a concentration of 0.1 mol / L at a solid-liquid ratio of 1 g:10 mL. After ultrasonic treatment for 5 min, chemical nickel plating was performed. The pH value of the plating solution was adjusted to 8.5 with ammonia water and the current density was 2 A / dm 2 The electroplating time was 20 min, followed by filtration and washing with ethanol / water (1:1), and drying at 60 ° C for 15 min to obtain Ni-coated CNTs; the electroplating solution used was water as a solvent and included the following components: 0.1 mol / L NiSO4, 0.5 mol / L H2SO4, 0.2 mol / L sodium hypophosphite and 0.01 wt% thiourea;

[0089] A3. Under the protection of Ar / H2 mixed gas, the Ni-coated CNT was heated to 800°C at a rate of 10°C / min, kept at this temperature for 30 minutes, and then CH4 and H2 were introduced. The mixture was kept at 820°C for 1.5 hours and then cooled to room temperature at a rate of 10°C / min to obtain a graphene-carbon nanotube hybrid material; the volume ratio of Ar and H2 was 95:5, the mixed gas flow rate was 50 sccm; the gas flow rate of CH4 was 55 sccm, and the gas flow rate of H2 was 25 sccm.

[0090] The method for preparing the high-strength and high-toughness cemented carbide material comprises the following steps:

[0091] S1. Pre-alloying of raw materials: Weigh the raw materials in the formula and perform ball milling. After drying the ball milled product, pre-sinter it at 1000°C for 2 hours under argon protection to obtain a pre-sintered green body;

[0092] S2, cold isostatic pressing: the pre-sintered green body obtained in step S1 is pressed at a pressure of 250 MPa and a holding time of 5 min to obtain a formed green body;

[0093] S3, sintering cryogenic treatment:

[0094] The formed green body obtained in step S2 was heated to 600°C at a heating rate of 10°C / min under an inert atmosphere and then hot-pressed and sintered. The pressing pressure was set to 40 MPa.

[0095] Then, the temperature was raised to 1400°C at a heating rate of 5°C / min, the pressure was set to 20 MPa, and the temperature was kept at this temperature for 1.5 hours to carry out the second sintering process.

[0096] The system was then transferred to a liquid nitrogen environment for treatment for 4 hours, and then the temperature was raised to room temperature at a rate of 5°C / min for cryogenic treatment; the temperature of the system was further raised to 1750°C at a rate of 10°C / min for vacuum sintering, and kept at this temperature for 45 minutes for the third sintering treatment.

[0097] S4. Stepwise aging treatment: The green body obtained in step S3 is naturally cooled to 620°C in the furnace and aged for 2 hours; then cooled to 320°C at a rate of 20°C / min in a vacuum environment and aged for 1.5 hours to obtain a high-strength and high-toughness cemented carbide material.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 1 is that the interface optimization material of this comparative example is obtained by mixing a high entropy alloy and a boride in a mass ratio of 8:3.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 1 is that the interface optimization material of this comparative example is obtained by mixing boride and carbonitride in a mass ratio of 7:4.

[0102] Comparative Example 3

[0103] This comparative example differs from Example 1 in that WC is used instead of the graphene-carbon nanotube hybrid material. Specifically, a high-strength and high-toughness cemented carbide material comprises the following raw materials by weight: 75.1 parts WC, 5 parts TiC, 10 parts Co-Ni alloy, 0.5 parts rare earth oxide, and 11 parts interface optimization material.

[0104] Comparative Example 4

[0105] This comparative example differs from Example 1 in that the proportion of the graphene-carbon nanotube hybrid material is increased in this comparative example. Specifically, a high-strength and high-toughness cemented carbide material comprises the following raw materials by weight: 75 parts WC, 5 parts TiC, 10 parts Co-Ni alloy, 0.5 parts rare earth oxide, 10 parts interface optimization material, and 1.1 parts graphene-carbon nanotube hybrid material.

[0106] Comparative Example 5

[0107] The difference between this comparative example and Example 1 is that in step S3, cryogenic treatment is performed after hot pressing sintering, the second sintering treatment, and the third sintering treatment. Specifically, the specific steps of sintering cryogenic treatment in this comparative example are:

[0108] The formed green body was heated to 600°C at a heating rate of 5°C / min under inert atmosphere and then hot-pressed and sintered. The pressing pressure was set to 20 MPa.

[0109] Then, the temperature was raised to 1400°C at a heating rate of 5°C / min, the pressure was set to 20 MPa, and the temperature was kept at that temperature for 1 hour to carry out the second sintering process;

[0110] The system temperature was further increased at 10°C / min to 1600°C for vacuum sintering and kept at this temperature for 30 minutes for the third sintering process;

[0111] The system was then transferred to a liquid nitrogen environment for 4 h and then the temperature was raised to room temperature at a rate of 5°C / min for cryogenic treatment.

[0112] The alloy materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-5 were made into samples with a specification of 10*10*50 mm.

[0113] Hardness: A microhardness tester (Leica HMV-2T) was used to test the hardness of the samples. Each sample was placed at room temperature (25°C) for 24 hours before the hardness test. The load was 200 g, the holding time was 10 seconds, and the average value of 5 test points was taken.

[0114] Bending strength test: Referring to the method in ISO 3327, the flexural strength of the product was tested using a three-point bending test with a span of 30 mm and a loading rate of 0.5 mm / min.

[0115] Fracture toughness test: The fracture toughness of the product was tested according to the method described in GB∕T 21143-2014, and the indentation load was set to 500N.

[0116] Impact toughness test: Using a 200J pendulum energy, calculate the ratio of impact energy to the cross-sectional area of the specimen to obtain the impact toughness value.

[0117] The specific performance test results are shown in Table 1:

[0118] Table 1

[0119]

[0120] From the test results, the product obtained in Example 2 showed the best properties such as hardness and flexural strength. The three embodiments were improved in hardness and toughness compared to the comparative examples. Specifically, in Examples 1-3, the reasonable ratio of high entropy alloy, boride and carbonitride was used to synergistically improve strength and toughness, while the performance of Comparative Example 1-2 was reduced due to the imbalance of boride or carbonitride ratio. Comparative Example 3 (the group without hybrids) showed a 15% decrease in strength due to coarsening of WC grains, while in the group of Comparative Example 4, adding a higher content of hybrids also led to a decrease in alloy performance, especially in hardness. Comparative Example 5 was cryogenically treated later, and the residual stress was not fully released, and both fracture toughness and impact toughness decreased.

[0121] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0122] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A high-strength and high-toughness cemented carbide material, characterized in that: It is composed of the following raw materials in parts by weight: 75-80 parts of WC, 5-8 parts of TiC, 10-12 parts of Co-Ni alloy, 0.5-1 parts of rare earth oxide, 11-15 parts of interface optimization material and 0.1-0.15 parts of graphene-carbon nanotube hybrid material; The preparation method thereof comprises the following steps: S1. Pre-alloying of raw materials: Weigh the raw materials in the formula and perform ball milling. After drying the ball milled product, pre-sinter it at 900-1000°C for 1.5-2h under inert atmosphere to obtain a pre-sintered green body; S2, cold isostatic pressing: the pre-sintered green body obtained in step S1 is pressed at a pressure of 200-250 MPa and a holding time of 5-7 min to obtain a formed green body; S3, sintering cryogenic treatment: The formed green body obtained in step S2 is heated to 600-650°C at a heating rate of 5-10°C / min under an inert atmosphere and then hot-pressed and sintered. The pressing pressure is set to 1-50 MPa. Then, the temperature is raised to 1400-1450°C at a heating rate of 1-5°C / min, the pressure is set to 18-20 MPa, and the temperature is kept at this temperature for 1-1.5 hours to carry out the second sintering process; The system is then transferred to a liquid nitrogen environment for 3-4 hours and then naturally restored to room temperature for cryogenic treatment; the system temperature is further increased at 5-10°C / min to 1600-1750°C for vacuum sintering, and kept at this temperature for 30-45 minutes for the third sintering step; S4, step-by-step aging treatment: the green body obtained in step S3 is naturally cooled to 600-620°C in the furnace, and aged for 1.5-2 hours; then cooled to 300-320°C at a rate of 10-20°C / min in a vacuum environment, and aged for 1-1.5 hours to obtain a high-strength and high-toughness cemented carbide material; The interface optimization material is obtained by mixing a high entropy alloy, a boride, and a carbonitride in a mass ratio of (8-10):(2-3):(1-2); The graphene-carbon nanotube hybrid material is prepared by the following steps: A1. Mixing multi-walled carbon nanotubes with a sulfuric acid solution, ultrasonically mixing for 20-30 minutes, then filtering and washing the precipitate with deionized water until the pH value of the washing solution is neutral to obtain pretreated carbon nanotubes; A2, immersing the pretreated carbon nanotubes in a PdCl2 solution, ultrasonically treating for 5-10 minutes, and then electrolessly plating nickel for 20-30 minutes, followed by filtering, washing, and drying to obtain Ni-coated CNTs; A3. Heat the Ni-coated CNT to 800-820°C under the protection of Ar / H2 mixed gas, keep warm for 20-30 minutes, then introduce CH4 and H2, keep warm at 800-820°C for 1-1.5 hours, and then cool to room temperature to obtain a graphene-carbon nanotube hybrid material.

2. The high-strength and high-toughness cemented carbide material according to claim 1, characterized in that: The high entropy alloy in the interface optimization material is at least one of AlCoCrFeNi and MoTaVW.

3. The high-strength and high-toughness cemented carbide material according to claim 1, characterized in that: The boride is at least one of FeB, CrB2, and TiB2, and the carbonitride is TiCN and / or C3N4.

4. The high-strength and high-toughness cemented carbide material according to claim 1, characterized in that: In step A3, the volume ratio of Ar to H2 in the Ar / H2 mixed gas is 95:5, and the flow rate of the mixed gas is 40-50 sccm.

5. The high-strength and high-toughness cemented carbide material according to claim 1, characterized in that: In step A3, the gas flow rate of CH4 is 45-55 sccm, and the gas flow rate of H2 is 15-25 sccm.

6. A method for preparing a high-strength and high-toughness cemented carbide material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Pre-alloying of raw materials: Weigh the raw materials in the formula and perform ball milling. After drying the ball milled product, pre-sinter it at 900-1000°C for 1.5-2h under inert atmosphere to obtain a pre-sintered green body; S2, cold isostatic pressing: the pre-sintered green body obtained in step S1 is pressed at a pressure of 200-250 MPa and a holding time of 5-7 min to obtain a formed green body; S3, sintering cryogenic treatment: The formed green body obtained in step S2 is heated to 600-650°C at a heating rate of 5-10°C / min under an inert atmosphere and then hot-pressed and sintered. The pressing pressure is set to 1-50 MPa. Then, the temperature is raised to 1400-1450°C at a heating rate of 1-5°C / min, the pressure is set to 18-20 MPa, and the temperature is kept at this temperature for 1-1.5 hours to carry out the second sintering process; The system is then transferred to a liquid nitrogen environment for 3-4 hours and then naturally restored to room temperature for cryogenic treatment; the system temperature is further increased at 5-10°C / min to 1600-1750°C for vacuum sintering, and kept at this temperature for 30-45 minutes for the third sintering step; S4, step-by-step aging treatment: the green body obtained in step S3 is naturally cooled to 600-620°C in the furnace and aging treated for 1.5-2h; Then, the material is cooled to 300-320°C at a rate of 10-20°C / min in a vacuum environment and subjected to aging treatment for 1-1.5 hours to obtain a high-strength and high-toughness cemented carbide material.

7. The method for preparing a high-strength and high-toughness cemented carbide material according to claim 6, characterized in that: In step S1, the specific parameters of the ball milling treatment are: a ball-to-material ratio of 4-5:1, a ball milling speed of 300-400 rpm, and a ball milling time of 20-30 h.

8. The method for preparing a high-strength and high-toughness cemented carbide material according to claim 6, characterized in that: In step S3, the pressure of hot pressing sintering is 40-50 MPa.

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