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

Abstract

The invention relates to a high-strength and high-toughness hard alloy material and a preparation method thereof, and belongs to the technical field of alloy material preparation, the hard alloy material specifically comprises the following raw materials by mass: 75-80 parts of WC, 5-8 parts of TiC, 10-12 parts of Co-Ni alloy, 0.5-1 part of rare earth oxide, 11-15 parts of an interface optimization material and 0.1-0.15 part of a graphene-carbon nanotube hybrid material; wherein the rare earth oxide is Y2O3; the interface optimization material is obtained by mixing high-entropy alloy, boride and carbonitride. A gradient interface is constructed by compounding the high-entropy alloy, the boride and the carbonitride, and the grain boundary pinning effect of the graphene-CNT hybrid material and the cryogenic-aging synergistic process are combined, so that the toughness contradiction of the traditional hard alloy is broken through, and an innovative solution is provided for high-end equipment manufacturing.

Description

Technical Field

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

[0002] As the "teeth" of modern industry, cemented carbides are widely used in fields such as cutting tools, mining machinery, aerospace, etc. The core of their performance lies in the synergistic effect between the hard phase and the binder phase. However, traditional cemented carbides face significant bottlenecks in strengthening and toughening: on the one hand, the coarsening of WC grains leads to an increase in crack sensitivity, and excessive addition of grain inhibitors such as VC, Cr 3 C 2 etc. Although it can refine the grains, it sacrifices toughness; on the other hand, the traditional binder phase Co is prone to softening at high temperatures, and is scarce in resources and high in cost, while the antioxidant and wettability of the alternative binder phases Ni or Fe are insufficient, resulting in weak interfacial bonding and limited service life.

[0003] In recent years, high-entropy alloys (HEAs) have been introduced into the field of cemented carbides due to their unique lattice distortion effect and "cocktail effect". Research shows that HEAs such as AlCoCrFeNi as the binder phase can refine WC grains to the sub-micron level, and at the same time enhance the interfacial bonding strength by forming strengthening phases such as Ni 3 Al, etc. However, the existing HEA system is single, and higher requirements are placed on the thermal stress buffering function achieved by the process during alloy preparation. Otherwise, it is easy to cause interfacial oxidation cracks and phase segregation problems.

[0004] In view of the above problems, it is urgent to develop a cemented carbide system with grain ultra-refinement, interfacial strengthening and toughening, and process controllability. Summary of the Invention

[0005] In order to solve the problems raised in the background art, 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, adopting the following technical scheme: A high-strength and high-toughness cemented carbide material, comprising the following raw materials in parts by mass: 75-80 parts of WC, 5-8 parts of TiC, 10-12 parts of Co-Ni alloy, 0.5-1 part of rare earth oxide, 11-15 parts of interface optimization material, and 0.1-0.15 part of graphene-carbon nanotube hybrid material; The interface optimization material is obtained by mixing a high-entropy alloy, a boride, and a carbonitride.

[0007] In the above technical solution, WC and TiC are used as hard phases in the alloy material. WC provides high hardness, and TiC enhances wear resistance and impact resistance; Co-Ni alloy is used as the toughening phase, and rare earth oxides inhibit abnormal growth of WC grains. Through Y 3+ occupying the grain boundary to reduce the interface energy, compounding with the graphene-carbon nanotube hybrid material components to further reduce grain coarsening during the sintering densification process, and inhibiting crack propagation by refining grains.

[0008] Further, the rare earth oxide is Y 2 O 3 .

[0009] Further, 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.

[0010] Further, the boride is at least one of FeB, CrB 2 , TiB 2 . Preferably, the boride is TiB 2 .

[0011] Further, the carbonitride is TiCN and / or C 3 N 4 .

[0012] Further, 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).

[0013] Further, the graphene-carbon nanotube hybrid material is prepared by the following steps: A1. Mix multi-walled carbon nanotubes with a sulfuric acid solution, perform ultrasonic mixing treatment 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; A2. Immerse the pretreated carbon nanotubes in a PdCl 2 solution, perform ultrasonic treatment for 5 - 10 min and then carry out electroless nickel plating for 20 - 30 min, then filter and wash and dry to obtain Ni-coated CNT; A3. Under the protection of an Ar / H 2 mixed gas, heat the Ni-coated CNT to 800 - 820 °C, keep it warm for 20 - 30 min, then introduce CH 4 and H 2 , keep it warm at 800 - 820 °C for 1 - 1.5 h, and then cool it to room temperature to obtain the graphene-carbon nanotube hybrid material.

[0014] Furthermore, the graphene-carbon nanotube hybrid material is prepared by the following steps: 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 liquid is neutral to obtain pretreated carbon nanotubes; A2. Immerse the pretreated carbon nanotubes in a PdCl 2 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, ultrasonically treat for 5 - 10 min and then carry out electroless nickel plating. Use ammonia water to adjust the pH value of the electroplating solution to 8.5, with a current density of 2 A / dm 2 , an electroplating time of 20 - 30 min, then filter and wash with ethanol solution, and dry at 60 °C to obtain Ni-coated CNT; A3. Under the protection of Ar / H 2 mixed gas, heat the Ni-coated CNT to 800 - 820 °C at a rate of 10 °C / min, keep it for 20 - 30 min, then introduce CH 4 and H 2 , keep it at 800 - 820 °C for 1 - 1.5 h, and then cool it to room temperature at a rate of 5 - 10 °C / min to obtain the graphene-carbon nanotube hybrid material.

[0015] In the above reaction process, the graphene-carbon nanotube hybrid material is prepared by in-situ chemical vapor deposition method. Specifically, first wash the multi-walled carbon nanotubes and deposit Ni nanoparticles on their surface. The Ni nanoparticles thereon act as catalysts. Subsequently, by means of vapor-phase chemical deposition and Ni catalysis, methane pyrolyzes to generate carbon atoms that deposit on the surface of CNT, forming few-layer graphene deposited on the carbon nanotubes to obtain the graphene-carbon nanotube hybrid material.

[0016] Furthermore, in step A2, the electroplating solution uses water as a solvent and includes the following components: 0.1 mol / L NiSO 4 , 0.5 mol / L H 2 SO 4 , 0.2 mol / L sodium hypophosphite and 0.01 wt% thiourea.

[0017] Preferably, in step A3, in the Ar / H 2 mixed gas, the volume ratio of Ar to H 2 is 95:5, and the flow rate of the mixed gas is 40 - 50 sccm.

[0018] Furthermore, in step A3, the gas flow rate of CH 4 is 45 - 55 sccm, and the gas flow rate of H 2 is 15 - 25 sccm.

[0019] A preparation method of a high-strength and high-toughness cemented carbide material, comprising the following steps: S1. Raw material pre-alloying: Weigh the raw materials in formula portions and perform ball milling. After drying the milled product, pre-sinter it at 900 - 1000 °C for 1.5 - 2 h under the protection of an inert atmosphere to obtain a pre-sintered blank. S2. Cold isostatic pressing forming: Press the pre-sintered blank obtained in step S1, set the pressing pressure to 200 - 250 Mpa, and the pressure holding time to 5 - 7 min to obtain a formed blank. S3. Sintering and cryogenic treatment: Heat the formed blank obtained in step S2 to 600 - 650 °C at a heating rate of 5 - 10 °C / min under the protection of an inert atmosphere and then perform hot pressing sintering, with the pressing pressure set to 1 - 50 Mpa. Subsequently, continue to raise the temperature to 1400 - 1450 °C at a heating rate of 1 - 5 °C / min, set the pressure to 18 - 20 Mpa, and keep the temperature for 1 - 1.5 h to perform the second sintering treatment. Subsequently, transfer the system to a liquid nitrogen environment for treatment for 3 - 4 h and then naturally restore the temperature to room temperature for cryogenic treatment; raise the temperature of the system to 1600 - 1750 °C at a rate of 5 - 10 °C / min for vacuum sintering, and keep the temperature for 30 - 45 min to perform the third sintering treatment.

[0020] S4. Step-by-step aging treatment: Slowly cool the blank obtained in step S3 in the furnace to 600 - 620 °C and perform aging treatment for 1.5 - 2 h; then cool it to 300 - 320 °C at a rate of 10 - 20 °C / min in a vacuum environment and perform aging treatment for 1 - 1.5 h to obtain a high-strength and high-toughness cemented carbide material.

[0021] During the above preparation process, through various forming and sintering treatments, the high-entropy alloy hinders the movement of dislocations through the lattice distortion effect, and at the same time, the precipitated strengthening phases such as Ni 3 Al, etc. improve the interface bonding strength; borides and carbonitrides are used as gradient strengthening layers to form a gradient interface, reduce the concentration of thermal stress, improve the interface bonding strength, and inhibit interface oxidation and crack initiation.

[0022] Cryogenic treatment can induce the dispersion precipitation of η-phase (Co 6 W 6 C) inside the WC hard phase, and at the same time promote the precipitation of phases with a body-centered cubic structure such as α-Fe in the high-entropy alloy to form a multi-scale strengthening network. Aging treatment optimizes the size of the precipitated phases and avoids strength loss caused by coarsening. Low-temperature aging stabilizes the interface structure and inhibits the performance degradation during long-term service. Through the synergy between cryogenic treatment and aging treatment, the strength, toughness, and wear resistance are further improved and optimized simultaneously.

[0023] Further, in step S1, the specific parameters of the ball milling treatment are as follows: the ball-to-material ratio is 4-5:1, the ball milling speed is 300-400 rpm, and the ball milling time is 20-30 h.

[0024] Further, in step S3, the pressure of the hot press sintering is 40-50 Mpa.

[0025] In summary, the present invention has the following beneficial effects: 1. In the technical solution of the present invention, a high-entropy alloy, a boride, and a carbonitride are compounded as an interface optimization material. The lattice distortion effect of the high-entropy alloy is used to hinder the movement of dislocations, and Ni 3 Al and other strengthening phases beneficial to interface bonding will be formed in the sintering process. The boride can form a gradient strengthening layer with WC at the interface to further strengthen the interface bonding. Combined with the carbonitride to form a continuous transition layer at high temperature, relieve the concentration of thermal stress, and reduce the generation of interface oxidation cracks. The three can well improve the interface bonding quality and thus improve the mechanical properties such as wear resistance and strength of the alloy under reasonable compounding.

[0026] 2. In the technical solution of the present invention, by preparing a graphene-carbon nanotube hybrid material, the performance of the alloy is optimized. The tubular structure of CNT is embedded in the WC grain boundary, combined with the two-dimensional plane of graphene to form a three-dimensional barrier network, and the WC grain coarsening is inhibited by grain boundary pinning. Compared with commercially available hybrid materials, the prepared product does not need to go through multiple steps such as pickling and etching to deal with the problem of subsequent metal catalyst impurities. The Ni coating is completely fused with the Co-Ni alloy during subsequent sintering. While saving costs, the metal Ni catalyst can also accelerate the heat mass transfer during the sintering process of the hybrid material, which is beneficial to improving the performance of the prepared alloy product.

[0027] 3. In the technical solution of the present invention, cryogenic treatment is set in the middle of the gradient heat treatment process, and aging treatment is finally set. Through one-time sintering, the grain boundary slip in the initial 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 realizes full densification. Subsequently, after cryogenic treatment, the third sintering is carried out. Cryogenic treatment promotes the diffusion of interface elements, promotes the precipitation of nano-scale Co 3 W 3 C phase in WC and α-Fe phase in the high-entropy alloy, promotes the formation of a "hard phase + tough phase" gradient structure, simultaneously inhibits carbide segregation, the uniformity of interface element distribution, improves the strength and toughness of the alloy material, and then the third sintering is carried out to strengthen the alloy network. Finally, step-by-step aging is carried out to suppress the coarsening of the phase to reduce the hardness fluctuation and improve the long-term service stability. Specific embodiments

[0028] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0029] The materials used in the embodiments and comparative examples of the present invention are all chemically pure. Among them, the Co-Ni alloy used has an average particle size of 100 μm, an impurity content of 0.01%, and a nickel content of 10%. The outer diameter of the carbon nanotubes used is 30-50 nm, and the purity is 98%.

[0030] High-entropy alloy AlCoCrFeNi: The particle size is 15-53 μm, provided by Beijing Yijin New Materials Technology Co., Ltd.

[0031] Example 1 A high-strength and high-toughness cemented carbide material, comprising the following raw materials in parts by mass: 75 parts of WC, 5 parts of TiC, 10 parts of Co-Ni alloy, 0.5 part of rare earth oxide, 11 parts of interface optimization material, and 0.1 part of graphene-carbon nanotube hybrid material; Among them, the rare earth oxide is Y 2 O 3 ; 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 TiB 2 , and the carbonitride is TiCN; The graphene-carbon nanotube hybrid material is prepared by the following steps: A1. Mix multi-walled carbon nanotubes with a 6 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g:10 mL, perform ultrasonic mixing treatment, set the ultrasonic power to 200 W, and the ultrasonic time to 20 min. Then filter and wash the precipitate with deionized water until the pH value of the washing liquid is neutral to obtain pretreated carbon nanotubes; A2. Immerse the pretreated carbon nanotubes in a PdCl 2 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, perform electroless nickel plating. Use ammonia water to adjust the pH value of the electroplating solution to 8.5, the current density to 2 A / dm 2 , and the electroplating time to 20 min. Then filter and wash with ethanol / water (1:1), and dry at 60 °C for 15 min to obtain Ni-coated CNT; the electroplating solution used is water-based and includes the following components: 0.1 mol / L NiSO 4 , 0.5 mol / L H2 SO 4 、 0.2 mol / L sodium hypophosphite and 0.01 wt% thiourea; A3. Heat the Ni-coated CNTs to 800 °C at a rate of 10 °C / min under the protection of an Ar / H 2 mixed gas, keep the temperature for 20 min, and then introduce CH 4 and H 2 . Keep the temperature at 80 °C for 1 h, and then cool to room temperature at a rate of 5 °C / min to obtain a graphene-carbon nanotube hybrid material; the volume ratio of Ar and H 2 is 95:5, and the flow rate of the mixed gas is 40 sccm; the gas flow rate of CH 4 is 45 sccm, and the gas flow rate of H 2 is 15 sccm.

[0032] The preparation method of the high-strength and high-toughness cemented carbide material includes the following steps: S1. Raw material pre-alloying: Weigh the raw materials in formula portions and perform ball milling. After drying the milled product, pre-sinter it at 1000 °C for 2 h under argon protection to obtain a pre-sintered blank. S2. Cold isostatic pressing: Press the pre-sintered blank obtained in step S1, set the pressing pressure to 200 Mpa, and keep the pressure for 5 min to obtain a formed blank. S3. Sintering and cryogenic treatment: Heat the formed blank obtained in step S2 to 600 °C at a heating rate of 5 °C / min under the protection of an inert atmosphere and then perform hot pressing sintering, with the pressing pressure set to 20 Mpa; Subsequently, continue to increase the temperature to 1400 °C at a heating rate of 5 °C / min, set the pressure to 20 Mpa, and keep the temperature for 1 h to perform the second sintering treatment; Subsequently, transfer the system to a liquid nitrogen environment for treatment for 4 h, and then increase the temperature to room temperature at a rate of 5 °C / min to perform cryogenic treatment; increase the temperature of the system to 1600 °C at a rate of 10 °C / min and perform vacuum sintering, and keep the temperature for 30 min to perform the third sintering treatment.

[0033] S4. Step-by-step aging treatment: Cool the blank obtained in step S3 to 600 °C in the furnace naturally and perform aging treatment for 1.5 h; then cool to 300 °C at a rate of 20 °C / min in a vacuum environment and perform aging treatment for 1 h to obtain a high-strength and high-toughness cemented carbide material.

[0034] Example 2 A high-strength and high-toughness cemented carbide material, including the following raw materials in parts by mass: 78 parts of WC, 7 parts of TiC, 11 parts of Co-Ni alloy, 0.8 part of rare earth oxide, 13 parts of interface optimization material, and 0.13 part of graphene-carbon nanotube hybrid material; Among them, the rare earth oxide is Y 2 O 3 ; 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 TiB 2 , and the carbonitride is TiCN; The graphene-carbon nanotube hybrid material is prepared by the following steps: A1. Mix multi-walled carbon nanotubes with 6 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g:10 mL, perform ultrasonic mixing treatment, set the ultrasonic power to 200 W, and the ultrasonic time to 30 min. Then filter and wash the precipitate with deionized water until the pH value of the washing liquid is neutral to obtain pretreated carbon nanotubes; A2. Immerse the pretreated carbon nanotubes at a solid-liquid ratio of 1 g:10 mL in a PdCl 2 solution with a pH value of 5 and a concentration of 0.1 mol / L. After ultrasonic treatment for 10 min, perform electroless nickel plating. Use ammonia water to adjust the pH value of the electroplating solution to 8.5, the current density to 2 A / dm 2 , and the electroplating time to 30 min. Then filter and wash with ethanol / water (1:1), and dry at 60°C for 15 min to obtain Ni-coated CNT; the electroplating solution uses water as a solvent and includes the following components: 0.1 mol / L NiSO 4 , 0.5 mol / L H 2 SO 4 , 0.2 mol / L sodium hypophosphite, and 0.01 wt% thiourea; A3. Under the protection of an Ar / H 2 mixed gas, heat the Ni-coated CNT to 800°C at a rate of 10°C / min, hold for 30 min, then introduce CH 4 and H 2 , hold at 810°C for 1.5 h, and then cool to room temperature at a rate of 10°C / min to obtain the graphene-carbon nanotube hybrid material; the volume ratio of Ar to H 2 is 95:5, and the flow rate of the mixed gas is 50 sccm; the gas flow rate of CH 4 is 50 sccm, and the gas flow rate of H 2 is 20 sccm.

[0035] The preparation method of the high-strength and high-toughness cemented carbide material includes the following steps: S1. Raw material pre-alloying: Weigh the raw materials in the formulated amounts and conduct ball milling. After drying the milled product, pre-sinter it at 1000 °C for 2 h under argon protection to obtain a pre-sintered green body. S2. Cold isostatic pressing: Press the pre-sintered green body obtained in step S1, set the pressing pressure to 230 Mpa, and the pressure holding time to 5 min to obtain a formed green body. S3. Sintering and cryogenic treatment: Heat press sinter the formed green body obtained in step S2 under inert atmosphere protection at a heating rate of 10 °C / min to 600 °C, and set the pressing pressure to 30 Mpa. Subsequently, continue to raise the temperature to 1400 °C at a heating rate of 5 °C / min, set the pressure to 20 Mpa, and hold for 1.5 h to conduct the second sintering treatment. Subsequently, transfer the system to a liquid nitrogen environment for 4 h, then raise the temperature to room temperature at a rate of 5 °C / min for cryogenic treatment; continue to raise the temperature of the system to 1700 °C at a rate of 10 °C / min for vacuum sintering, and hold for 40 min to conduct the third sintering treatment.

[0036] S4. Step-by-step aging treatment: Let the green body obtained in step S3 cool naturally in the furnace to 610 °C and conduct aging treatment for 2 h; then cool it to 310 °C at a rate of 20 °C / min in a vacuum environment and conduct aging treatment for 1.5 h to obtain a high-strength and high-toughness cemented carbide material.

[0037] Example 3 A high-strength and high-toughness cemented carbide material, comprising the following raw materials in parts by mass: 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 part of graphene-carbon nanotube hybrid material; Among them, the rare earth oxide is Y 2 O 3 ; 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 CrB 2 , and the carbonitride is C 3 N 4 ; The graphene-carbon nanotube hybrid material is prepared by the following steps: A1. Mix multi-walled carbon nanotubes with 6 mol / L sulfuric acid solution according to a solid-liquid ratio of 1 g:10 mL, conduct ultrasonic mixing treatment, set the ultrasonic power to 200 W, and the ultrasonic time to 30 min. Then filter and wash the precipitate with deionized water until the pH value of the washing liquid is neutral to obtain pretreated carbon nanotubes. A2. Immerse the pretreated carbon nanotubes in a PdCl solution with a solid-liquid ratio of 1 g:10 mL, a pH value of 5, and a concentration of 0.1 mol / L. After ultrasonic treatment for 5 min, electroless nickel plating is carried out. Use ammonia water to adjust the pH value of the electroplating solution to 8.5, with a current density of 2 A / dm 2 , an electroplating time of 20 min, then filter and wash with ethanol / water (1:1), and dry at 60 °C for 15 minutes to obtain Ni-coated CNT. The electroplating solution used has water as the solvent and includes the following components: 0.1 mol / L NiSO 2 , 0.5 mol / L H 4 SO 2 , 0.2 mol / L sodium hypophosphite, and 0.01 wt% thiourea; 4 A3. Under the protection of an Ar / H 2 mixed gas, heat the Ni-coated CNT to 800 °C at a rate of 10 °C / min, hold for 30 min, then introduce CH 4 and H 2 , hold at 820 °C for 1.5 h, and then cool to room temperature at a rate of 10 °C / min to obtain the graphene-carbon nanotube hybrid material; the volume ratio of Ar and H 2 is 95:5, and the flow rate of the mixed gas is 50 sccm; the gas flow rate of CH 4 is 55 sccm, and the gas flow rate of H 2 is 25 sccm.

[0038] The preparation method of the high-strength and high-toughness cemented carbide material includes the following steps: S1. Raw material pre-alloying: Weigh the raw materials in formula portions and carry out ball milling. After drying the ball-milled product, pre-sinter at 1000 °C for 2 h under argon protection to obtain a pre-sintered blank; S2. Cold isostatic pressing: Press the pre-sintered blank obtained in step S1, set the pressing pressure to 250 Mpa, and the pressure holding time to 5 min to obtain a formed blank; S3. Sintering and cryogenic treatment: Heat the formed blank obtained in step S2 to 600 °C at a heating rate of 10 °C / min under the protection of an inert atmosphere and then carry out hot pressing sintering, with the pressing pressure set to 40 Mpa; Subsequently, continue to increase the temperature to 1400 °C at a heating rate of 5 °C / min, set the pressure to 20 Mpa, and hold for 1.5 h to carry out the second sintering treatment; Subsequently, transfer the system to a liquid nitrogen environment for treatment for 4 h, then increase the temperature to room temperature at a rate of 5 °C / min for cryogenic treatment; continue to increase the temperature of the system to 1750 °C at a rate of 10 °C / min for vacuum sintering, and hold for 45 min to carry out the third sintering treatment.​

[0039] S4. Step-by-step aging treatment: The green body obtained in step S3 is naturally cooled in the furnace to 620 °C and aged for 2 h; then it is cooled to 320 °C at a rate of 20 °C / min in a vacuum environment and aged for 1.5 h, thus obtaining a high-strength and high-toughness cemented carbide material.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that the interface optimization material in this comparative example is obtained by mixing a high-entropy alloy and a boride in a mass ratio of 8:3.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that the interface optimization material in this comparative example is obtained by mixing a boride and a carbonitride in a mass ratio of 7:4.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that WC is used instead of the graphene-carbon nanotube hybrid material in this comparative example. Specifically, a high-strength and high-toughness cemented carbide material comprises the following raw materials in parts by mass: 75.1 parts of WC, 5 parts of TiC, 10 parts of Co-Ni alloy, 0.5 part of rare earth oxide, and 11 parts of interface optimization material.

[0043] Comparative Example 4 The difference between this comparative example and Example 1 is 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 in parts by mass: 75 parts of WC, 5 parts of TiC, 10 parts of Co-Ni alloy, 0.5 part of rare earth oxide, 10 parts of interface optimization material, and 1.1 parts of graphene-carbon nanotube hybrid material.

[0044] Comparative Example 5 The difference between this comparative example and Example 1 is that in step S3, cryogenic treatment is carried out after hot press sintering, the second sintering treatment, and the third sintering treatment. Specifically, the specific steps of the sintering cryogenic treatment in this comparative example are as follows: The formed green body is heated to 600 °C at a heating rate of 5 °C / min under the protection of an inert atmosphere and then hot press sintered, and the pressing pressure is set to 20 Mpa; Subsequently, the temperature is continuously increased to 1400 °C at a heating rate of 5 °C / min, the pressure is set to 20 Mpa, and it is kept warm for 1 h to carry out the second sintering treatment; The system is continuously heated to 1600 °C at 10 °C / min for vacuum sintering, and it is kept warm for 30 min to carry out the third sintering treatment; Subsequently, the system is transferred to a liquid nitrogen environment and treated for 4 h, and then the temperature is increased to room temperature at a rate of 5 °C / min to carry out cryogenic treatment.

[0045] The alloy materials prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention were made into samples with a specification of 10*10*50 mm.

[0046] Hardness: The hardness was tested using a microhardness tester (Leica HMV-2T). Before the hardness test of each sample, it was placed at room temperature (25 °C) for 24 h, the load was 200 g, the holding time was 10 s, and the average value was taken by testing 5 points.

[0047] Flexural strength test: Referring to the method in ISO 3327, the flexural strength of the product was tested by a three-point bending test, with the span set at 30 mm and the loading rate at 0.5 mm / min.

[0048] Fracture toughness test: Referring to the method described in GB∕T 21143-2014, the fracture toughness of the product was tested, and the indentation load was set at 500 N.

[0049] Impact toughness test: Using a 200 J pendulum energy, the ratio of the impact work to the cross-sectional area of the specimen was calculated to obtain the impact toughness value.

[0050] The specific performance test results are shown in Table 1 below: Table 1

[0051] Judging from the test results, the products prepared in Example 2 showed the best performance in terms of hardness, flexural strength, etc. Compared with the comparative examples, the three examples had improvements in terms of hardness and toughness. Specifically, in Examples 1-3, through the reasonable ratio of high-entropy alloy, boride and carbonitride, the strength and toughness were synergistically improved, while in Comparative Examples 1-2, the performance decreased due to the imbalance of the ratio of boride or carbonitride. In Comparative Example 3 (the group without hybrid), the strength decreased by 15% due to the coarsening of WC grains, and in the group of Comparative Example 4, adding a relatively large amount of hybrid also led to a decrease in the alloy performance, especially in terms of hardness. In Comparative Example 5, the cryogenic treatment was delayed, and the residual stress could not be fully released, resulting in a decrease in both fracture toughness and impact toughness.

[0052] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0053] The above content is only an example and illustration of the present invention. Those skilled in the art to which the present technology pertains may make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A high-strength and high-toughness cemented carbide material, characterized in that: Including 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; The interface optimization material is obtained by mixing a high entropy alloy, a boride and a carbonitride.

2. A 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, AlCoCrFeNi, and MoTaVW.

3. The high-strength and high-toughness cemented carbide material according to claim 1, characterized in that: 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).

4. 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.

5. The high-strength and high-toughness cemented carbide material according to claim 1, characterized in that: 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 min, and then chemically plating nickel for 20-30 min, followed by filtering, washing and drying to obtain Ni-plated CNTs; A3. Heat the Ni-coated CNT to 800-820°C under the protection of Ar / H2 mixed gas, keep the temperature for 20-30 minutes, then introduce CH4 and H2, keep the temperature at 800-820°C for 1-1.5 hours, and then cool to room temperature to obtain a graphene-carbon nanotube hybrid material.

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

7. The high-strength and high-toughness cemented carbide material according to claim 5, 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.

8. A method for preparing a high-strength and high-toughness cemented carbide material as claimed in any one of claims 1 to 7, 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 the ball milled product is dried, it is pre-sintered at 900-1000° C. for 1.5-2h under the protection of an inert atmosphere to obtain a pre-sintered green body; S2, cold isostatic pressing: the pre-sintered green body obtained in step S1 is pressed, the pressing pressure is set to 200-250 MPa, and the holding time is 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, with the pressing pressure set to 1-50Mpa; Then, the temperature is further increased to 1400-1450°C at a heating rate of 1-5°C / min, the pressure is set to 18-20Mpa, and the temperature is kept for 1-1.5h to carry out the second step of sintering treatment; Then, the system is 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 the temperature is kept for 30-45 minutes for the third step of sintering treatment; 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 treatment is performed 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 1-1.5h to obtain a high-strength and high-toughness cemented carbide material.

9. The method for preparing a high-strength and high-toughness cemented carbide material according to claim 8, characterized in that: In step S1, the specific parameters of the ball milling treatment are: ball-to-material ratio is 4-5:1, ball milling speed is 300-400 rpm, and ball milling time is 20-30 h.

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

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