High-toughness cermets and cutting tools

Abstract

A high-toughness cermet and a method for producing the same are provided. [Solution] A high-toughness cermet is (1) primarily composed of titanium carbide, nitride, carbonitride, or any composition thereof, and (2) a carbide, nitride, carbonitride, or any composition thereof of at least one metal element selected from Groups IVB, VB, and VIB of the periodic table excluding titanium, and when (1) and (2) are different, the high-toughness cermet comprises a hard phase which is a nitride, a binder phase which is at least two transition metals, cobalt, nickel, and iron, and a metal reinforcer which is at least two of tantalum, niobium, manganese, ruthenium, rhenium, yttrium, and cerium, and at least one of tantalum, niobium, and manganese, and which is finely and uniformly dispersed throughout the microstructure of the cermet, and the hard phase contains dispersion-strengthened hard phase precipitates which are precipitated by reaction of some of the metal elements of the metal reinforcer with carbon.

Description

[Technical Field]

[0001] The present disclosure belongs to the technical field of cermets, and more particularly to high-toughness cermets and their Cutting tool including a substrate made of high-toughness cermet Regarding. [Background technology]

[0002] Ti(C,N)-based cermets are an upgraded alternative to cemented carbide materials. Their higher wear resistance, lower friction coefficient with metals, superior high-temperature performance, and oxidation resistance make them well-suited for continuous, dry cutting at high speeds, high precision, and higher feed rates, significantly improving cutting efficiency and service life. Ti(C,N)-based cermets are manufactured by powder metallurgy to combine soft transition metals (Ni, Co) with ceramic matrix phases such as TiC, TiN, and Ti(C,N) and secondary carbides (e.g., Mo2C, WC, TaC, etc.). These composites offer high hardness and wear resistance, and their material properties effectively fill the gaps in cutting cemented carbide and oxide ceramic materials, resulting in excellent surface finishes and making them widely used in high-speed, precision cutting applications. With the current demand for constantly improving machining efficiency, cermets are operated under high-temperature and high-speed cutting conditions, which highlights the poor chipping resistance of ceramics, making them prone to sudden chipping, shortening tool life, and affecting the surface finish of the workpiece. In order to obtain desirable properties such as yield strength, red hardness, plastic deformation resistance, and wear resistance, cermet processing currently used in steel material machining is based on scientific theories such as solid solution strengthening, dispersion strengthening, and grain boundary strengthening of materials. The ingredients are There is still room for improvement. Summary of the Invention [Problem to be solved by the invention]

[0003] In order to solve the problems existing in the prior art, the present invention provides a high-toughness cermet and its A cutting tool including a substrate made of such a high-toughness cermet. The main purpose is to propose [Means for solving the problem]

[0004] a hard phase, a binder phase, and tantalum and at least one element selected from the group consisting of niobium, manganese, ruthenium, rhenium, yttrium, and cerium, added as a metal strengthener; the hard phase includes titanium carbonitride, tungsten, tantalum, and niobium carbides, molybdenum carbide, and at least one of molybdenum carbide and niobium carbide; The binder phase is composed of cobalt and nickel. A high-toughness cermet characterized by:

[0005] Preferably, the binder phase accounts for 10 to 24 wt % of the total amount of the cermet, and the hard phase accounts for 76 to 90 wt % of the total amount of the cermet.

[0006] Preferably, the grain size of the hard phase is 0.5 to 5.0 μm, more preferably 0.8 to 2.0 μm.

[0007] Preferably, the metal strengthening agent comprises at least one of tantalum, niobium, and manganese, with tantalum accounting for 0.35 to 6.0 wt% of the total cermet, niobium for 0.2 to 2.0 wt% of the total cermet, and manganese for 0.3 to 4.0 wt% of the total cermet.

[0008] Preferably, the metal strengthening agent comprises at least one of tantalum, niobium, and manganese, with tantalum accounting for 0.4 to 2.4 wt% of the total cermet, niobium accounting for 0.3 to 0.8 wt% of the total cermet, and manganese accounting for 0.5 to 2.0 wt% of the total cermet.

[0009] Preferably, the mass ratio of tantalum to niobium added to the binder phase is (1-4):1, preferably 2:1.

[0010] Preferably, the proportion of manganese participating in the binder phase in the metal reinforcement is ≦50 wt%, preferably ≦33.3 wt%.

[0011] Preferably, in the same scanning electron microscope photograph, the hard phase comprises a first hard phase and a second hard phase, wherein the first hard phase mainly appears as a phase with a black core and a gray outer periphery structure and a phase with a black gray structure, and the first hard phase is mainly composed of titanium carbide, titanium nitride, and titanium carbonitride, the second hard phase mainly appears as a phase with a light color core and a gray outer periphery structure, the binder phase mainly exhibits a phase with a medium brightness structure, and there are a large number of micro-nano precipitated phases precipitated in a dot shape at the interface between the binder phase and the hard phase.

[0012] S1 prepares the metal reinforcement material; (1) A mixture mainly consisting of titanium carbide, nitride, carbonitride, or any composition thereof, and (2) a mixture mainly consisting of at least one metal element selected from Groups IVB, VB, and VIB of the periodic table excluding titanium, consisting of a carbide, nitride, carbonitride, or any composition thereof, and when (1) and (2) are different, a hard phase powder which is a nitride and a binder phase powder which is at least two transition metals selected from cobalt, nickel, and iron are prepared, and then the hard phase powder, binder phase powder, metal reinforcement material, solvent, and binder powder in step S1 are mixed, and the mixture is again ball-milled, followed by spray preparation to obtain a mix (S2); S3 press-molding the mix to obtain a green compact; and (S4) placing the powder compact into a sintering furnace, heating it to a temperature for removing the binder in a predetermined sintering process, removing the binder, and then sintering in a micro-pressure atmosphere, during which some metal particles of the metal reinforcement react with carbon to form fine dispersion-strengthened hard phase precipitates dispersed in the hard phase, and other metal particles of the metal reinforcement dissolve in the binder phase to form a solid-solution-strengthened binder phase, thereby finally obtaining a high-toughness cermet.

[0013] Preferably, in step S1, the metal strengthening raw material comprises metal powder, oxide, complex, salt, or any composition thereof of at least two metal elements selected from the group consisting of tantalum, niobium, manganese, ruthenium, rhenium, yttrium, and cerium.

[0014] Preferably, in step S1, the metal reinforcement raw material is mixed with a molding agent and a solvent, pulverized in a ball mill, dried, and then subjected to hydrogen reduction treatment to obtain ultrafine metal particles as the metal reinforcement, and the particle size of the metal reinforcement is 100 to 500 nm.

[0015] Preferably, in step S1, the hydrogen reduction temperature is 400 to 800°C.

[0016] Preferably, in steps S1 and S2, the molding agent is at least one selected from paraffin having a melting point of 48 to 56°C and PEG1000 to PEG20000, and the solvent is at least one selected from absolute ethanol and deionized water.

[0017] Preferably, in step S2, the amount of metal strengthening agent added is 0.5 to 5 wt % of the total amount of the cermet, and more preferably 1.2 to 3.6%.

[0018] Preferably, in step S4, the atmosphere in the sintering furnace during the molding agent removal process is a hydrogen atmosphere or a vacuum atmosphere; In step S1, when the metal reinforcement raw material is subjected to hydrogen reduction treatment, the atmosphere in the sintering furnace during the molding agent removal process is a vacuum atmosphere; In step S1, when the metal reinforcement raw material is directly used, the atmosphere in the sintering furnace during the binder removal process is a hydrogen atmosphere.

[0019] Preferably, in step S4, the micropressure atmosphere sintering is performed by, specifically, raising the temperature to temperature A, introducing x mbar of process gas, and then raising the temperature to temperature B in a nitrogen atmosphere at a heating rate of 2 to 10°C / min, followed by vacuum sintering, maintaining the temperature at temperature B for 0.5 to 3 hours, then cooling to 1200°C in a process gas partial pressure atmosphere of y mbar, and finally high-pressure cooling in an argon atmosphere, where temperature A is 1000 to 1400°C, temperature B is 1400 to 1600°C, x is 0.5 to 60, y is 10 to 100, and the process gas is at least one selected from nitrogen, argon, and helium.

[0020] A cutting tool including a substrate made of the cermet or a cermet manufactured by the manufacturing method. [Effects of the Invention]

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention The alloy comprises a hard phase, a binder phase, and at least one element selected from the group consisting of tantalum, niobium, manganese, ruthenium, rhenium, yttrium, and cerium added as a metal strengthening agent, wherein the hard phase includes titanium carbonitride, tungsten, tantalum, and niobium carbides, molybdenum carbide, and at least one of molybdenum carbide and niobium carbide, and the binder phase is made of cobalt and nickel. High toughness cermet characterized by To The present invention improves the overall performance of cermets, including hardness, toughness, high-temperature stability, and wear resistance, by using dispersion strengthening of the hard phase and solid-solution strengthening of the binder phase.

[0023] (1) Regarding the improvement of hardness and wear resistance, the hard phase is formed by introducing carbide, nitride, carbonitride, or a combination thereof of at least one metallic element selected from Groups IVB, VB, and VIB of the periodic table, primarily titanium, and by combining this with dispersion-strengthened hard phase precipitates formed by the reaction of the metal strengthener with carbon, the hardness and wear resistance of the material are significantly improved.

[0024] (2) Strengthening of the binder phase: At least two of the transition metals cobalt, nickel, and iron are used as the matrix for the binder phase, and these metals have good plasticity and toughness. In addition, some of the metal elements in the metal strengthener dissolve in the binder phase to form a solid-solution strengthened binder phase, further improving the strength and toughness of the binder phase.

[0025] (3) Regarding the improvement of high-temperature stability, the fine and uniform distribution of metal reinforcement in the cermet effectively suppresses grain growth and phase transformation at high temperatures, thereby enhancing the thermal stability and creep resistance of the material.

[0026] (4) Regarding the improvement of overall performance, the two-phase strengthening design, i.e., dispersion strengthening of the hard phase and solid solution strengthening of the binder phase, improves the overall performance of the cermet, such as hardness, toughness, high-temperature stability, and wear resistance. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is an electron microscope photograph of the internal structure of the cermet according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] This invention proposes a high-strength and toughness cermet and its manufacturing method, which is designed based on solid solution strengthening of the binder phase, and improves material hardness and high-temperature performance through dispersed precipitation and carburization of mildly supersaturated strengthening metals.

[0029] Ta has excellent high-temperature corrosion resistance and a large atomic radius, 15% to 18% larger than that of Ni, Co, and Fe. The addition of Co and Ni binder phase solid solutions further increases the lattice constant, increasing the resistance to dislocation motion in the elastic stress field formed. Ta can also reduce the stacking fault energy of the gamma solid solution. Research has shown that the strong oxidation properties of tantalum inhibit the shish-kebab creep of the gamma phase. The alloys with tantalum added have better high-temperature strength than the control, and their creep rate is reduced by nearly half, significantly improving the instantaneous tensile strength and creep performance of the gamma solid solution.

[0030] Nb is one of the commonly used solid solution strengthening elements. Its atomic radius is larger than that of W and Mo, and 15-18% larger than that of Ni, Co, and Fe atoms. The increase in the lattice constant of Nb is more significant than that of W and Mo, so Nb's solid solution strengthening effect is greater. Nb significantly reduces the stacking fault energy of the γ matrix, thereby significantly reducing the creep rate and improving creep performance. Nb is also a carbide-forming element and acts as a grain growth inhibitor, capable of refining the structure while dispersing phases, significantly improving the alloy's thermal hardness, thermal shock resistance, hot pressure resistance, and oxidation resistance.

[0031] The refractory metal Re has an atomic radius 10% larger than that of Ni and its chemical properties are similar to those of manganese and technetium. It enters the binder phase, dissolves, causes lattice distortion, generates an elastic stress field, inhibits dislocation movement, and increases the strength of Re-containing alloys.

[0032] Ru strengthens the alloy by expanding the lattice of the alloy and generating a long-range stress field. Ru dissolves mainly in the γ phase, giving the alloy a large negative mismatch, which extends the durability life of the alloy at high temperatures and low stresses.

[0033] The electron shell configuration of rare earth elements is different from that of conventional elements, which gives rare earth elements high binding energy and strong coordination ability, filling crystal vacancies and reducing the number of crystal defects, thereby playing an important role in stabilizing and improving the crystal structure.

[0034] Preferably, as shown in FIG. 1, in the same scanning electron microscope photograph, the hard phase includes a first hard phase 1 and a second hard phase 2, wherein the first hard phase 1 mainly appears as a phase with a black core and a gray outer periphery structure and a phase with a black gray structure, and the first hard phase 1 is mainly composed of titanium carbide, titanium nitride, and titanium carbonitride, the second hard phase 2 mainly appears as a phase with a light color core and a gray outer periphery structure, the solid-solution strengthened binder phase 3 mainly exhibits a phase with a medium brightness structure, and there are a large number of micro-nano precipitated phases 4 precipitated in a dot shape at the interface between the solid-solution strengthened binder phase 3 and the hard phase.

[0035] Example 1 S1, in which tantalum and niobium oxides are mixed in a mass ratio of 2:1, converted into equivalent amounts, and PEG2000 is added. The mixture is ball-milled in absolute alcohol for 20 hours, spray-dried, and then reduced and sintered in a pusher-type continuous firing furnace at 700°C in a hydrogen atmosphere to obtain ultrafine metal particles as a metal reinforcing agent; The raw materials selected were metal reinforcement, cobalt / nickel binder powder, titanium-containing cubic carbonitride powder, molybdenum carbide powder, tungsten, tantalum, and niobium carbide powder, and tungsten carbide. The mass percentage of each raw material was 1.5 wt% for the metal reinforcement, 15 wt% for the cobalt / nickel binder powder, 50 wt% for the titanium-containing cubic carbonitride powder, 15 wt% for the tungsten, tantalum, and niobium solid solution carbide, and 2 wt% for the molybdenum carbide powder. t% and the remainder is tungsten carbide, the sum of the mass percentages of each raw material is 100wt%, the powder particle size is <1.8μm, and the metal reinforcement agent, cobalt / nickel binder phase powder, titanium-containing cubic carbonitride powder, tungsten, tantalum, niobium solid solution carbide, molybdenum carbide powder, tungsten carbide and molding agent are ball milled using paraffin (content 2.0wt%) as molding agent and absolute ethanol as solvent, and then dried to obtain a mixed powder; S2 S3 press-molding the mix to obtain a green compact; S4, heating the powder compact to the binder removal temperature in a vacuum atmosphere, removing the binder, heating the powder compact from which the binder has been removed to 1150°C in a vacuum atmosphere, introducing 50 mbar nitrogen gas, and then sintering the powder compact by heating to 1450°C in a nitrogen atmosphere at a heating rate of 6°C / min, followed by vacuum sintering and maintaining the temperature at 1450°C for 1.5 hours, then cooling to 1200°C in an argon atmosphere at 30 mbar, and finally cooling to room temperature under high pressure in an argon atmosphere to obtain a cermet.

[0036] Example 2 S1 selects oxides of tantalum and niobium as metal strengthening agents in a mass ratio of tantalum and niobium of 2:1, converted into equivalent amounts; The raw materials selected were tantalum and niobium oxides, which were converted into equivalent amounts at a mass ratio of tantalum and niobium of 2:1, cobalt / nickel binder phase powder, titanium-containing cubic carbonitride powder, molybdenum carbide powder, tungsten, tantalum, and niobium solid solution carbide, and tungsten carbide. The mass percentages of each raw material were as follows: the total of tantalum and niobium in the tantalum and niobium oxide powder (mass ratio of tantalum and niobium of 2:1) was 1.5 wt%, the cobalt / nickel binder phase powder was 15 wt%, and the titanium-containing cubic carbonitride powder was 50 wt%. S2, in which the ultrafine metal powder, cobalt / nickel binder phase powder, titanium-containing cubic carbonitride powder, tungsten, tantalum, niobium solid solution carbides, molybdenum carbide powder, tungsten carbide and a binder are ball milled using paraffin (content 2.0 wt%) as a binder and absolute ethanol as a solvent, and then dried to obtain a mixed powder; S3 press-molding the mix to obtain a green compact; S4, heating the powder compact in a hydrogen gas atmosphere to a binder removal temperature of 700°C, removing the binder, heating the powder compact from which the binder has been removed to 1150°C under vacuum atmosphere conditions, introducing nitrogen gas at 50 mbar, and then sintering the powder compact by heating to 1450°C in a nitrogen atmosphere at a heating rate of 6°C / min, followed by vacuum sintering and maintaining the temperature at 1450°C for 1.5 hours, followed by cooling to 1200°C in an argon atmosphere at 30 mbar, and finally cooling to room temperature under high pressure in an argon atmosphere to obtain a cermet.

[0037] Example 3 S1 is a mixture of tantalum oxide and ammonium rhenate in a ratio of tantalum oxide and ammonium rhenate converted into equivalent amounts with a mass ratio of tantalum and rhenium of 1:1, PEG2000 is added, the mixture is ball milled in absolute alcohol for 20 hours, spray dried, and then reduced and sintered at 700°C in a hydrogen atmosphere in a pusher-type continuous firing furnace to obtain ultrafine metal particles as a metal reinforcement agent; The raw materials selected were a metal reinforcement, a cobalt / nickel binder phase powder, a titanium-containing cubic carbonitride powder, a molybdenum carbide powder, and tungsten, tantalum, and niobium carbide powders. The mass percentages of each raw material were 2 wt% for the metal reinforcement, 15 wt% for the cobalt / nickel binder phase powder, 55 wt% for the titanium-containing cubic carbonitride powder, 10 wt% for the tungsten, tantalum, and niobium solid solution carbides, and 1.8 wt% for the molybdenum carbide powder. S2, in which the remaining mass percentage of each raw material is 100 wt%, the powder particle size is less than 1.8 μm, the metal reinforcement material, the cobalt / nickel binder powder, the titanium-containing cubic carbonitride powder, the tungsten, tantalum, niobium solid solution carbide, the molybdenum carbide powder, the tungsten carbide and the molding agent are ball-milled using paraffin (content 2.0 wt%) as the molding agent and absolute ethanol as the solvent, and then dried to obtain a mixed powder;

[0038] S3 press-molding the mix to obtain a green compact; S4, heating the powder compact to the binder removal temperature in a vacuum atmosphere, removing the binder, heating the powder compact from which the binder has been removed to 1150°C in a vacuum atmosphere, introducing nitrogen gas at 50 mbar, and then sintering the powder compact by heating to 1450°C in a nitrogen atmosphere at a heating rate of 6°C / min, followed by vacuum sintering and maintaining the temperature at 1450°C for 1.5 hours, then cooling to 1200°C in an argon atmosphere at 30 mbar, and finally cooling to room temperature under high pressure in an argon atmosphere to obtain a cermet.

[0039] Example 4 S1 is a mixture of tantalum oxide, yttrium oxide, and manganese carbonate in a mass ratio of 1:1:1, where the tantalum, yttrium, and manganese are converted into equivalent amounts of tantalum oxide, yttrium oxide, and manganese carbonate, and PEG2000 is added. The mixture is ball-milled in absolute alcohol for 20 hours, spray-dried, and then reduced and sintered at 700°C in a hydrogen atmosphere in a pusher-type continuous firing furnace to obtain ultrafine metal particles as a metal reinforcing agent. The raw materials selected were a metal reinforcement, a cobalt / nickel binder phase powder, a titanium-containing cubic carbonitride powder, a molybdenum carbide powder, and tungsten, tantalum, and niobium carbide powders. The mass percentages of each raw material were 1.5 wt% for the metal reinforcement, 15 wt% for the cobalt / nickel binder phase powder, 52.5 wt% for the titanium-containing cubic carbonitride powder, 10 wt% for the tungsten, tantalum, and niobium solid solution carbides, and 2 wt% for the molybdenum carbide powder. S2, in which the metal reinforcement agent, cobalt / nickel binder powder, titanium-containing cubic carbonitride powder, tungsten, tantalum, niobium solid solution carbide, molybdenum carbide powder, tungsten carbide, and a binder are ball-milled using paraffin (content 2.0 wt%) as a binder and absolute ethanol as a solvent, and the remainder is tungsten carbide, the total mass percentage of each raw material is 100 wt%, and the powder particle size is less than 1.8 μm. S3, in which the metal reinforcement agent, cobalt / nickel binder powder, titanium-containing cubic carbonitride powder, tungsten, tantalum, niobium solid solution carbide, molybdenum carbide powder, tungsten carbide, and a binder are ball-milled using paraffin (content 2.0 wt%) as a binder and absolute ethanol as a solvent, and the mixture is dried to obtain a mixed powder; S3 press-molding the mix to obtain a green compact; S4. A method for producing a high-toughness cermet, comprising: heating the powder compact in a vacuum atmosphere to the binder removal temperature; removing the binder; heating the powder compact from which the binder has been removed in a vacuum atmosphere to 1150°C; introducing nitrogen gas at 50 mbar; sintering the powder compact by heating it to 1450°C in a nitrogen atmosphere at a heating rate of 6°C / min; subsequently, transferring to vacuum sintering; maintaining the temperature at 1450°C for 1.5 hours; subsequently cooling to 1200°C in an argon atmosphere at 30 mbar; and finally, high-pressure cooling to room temperature in an argon atmosphere to obtain a cermet.

[0040] Comparative Example 1 The difference from Example 1 is that step S1 was not performed, and a cermet material was produced using Co powder and Ni powder in a mass ratio of 1:1 as a composite powder of the binder phase, with the same mass fraction of each component element being added as their carbides.

[0041] For the cermet materials obtained in each example and comparative example, the sample material was split in half using a Discotom-100 metallography cutter, then shrink fitted with phenolic resin using a Citpress-20 semi-automatic shrink fitting device, and then placed in an AbraPol-20 automatic microprocessor-controlled vertical polishing machine to prepare specimens. After polishing to 80, 220, 500, 1200, and 4000 grits, the Vickers hardness (HV) and fracture toughness (Kic) of the specimens were measured using an FLC50V-ARS9000 fully automatic micro Vickers hardness tester, and the results are shown in the table below.

[0042] [Table 1]

[0043] The cermet materials obtained in each example and comparative example were cut and shaped to form tool blanks. The tool blades were rounded using a nylon brush containing SiC. PVD / CVD coatings were then formed on the surface of the tool blanks to obtain coated cermet tools.

[0044] Comparative test data and test results under different cutting conditions for the coated cermet tools of each Example and Comparative Example are as follows:

[0045] A 40CrNi2Mo steel bar was turned longitudinally to compare the wear resistance of the above-mentioned tools. The tool life standard is the machining time when flank wear is 0.3 mm. See the following table for cutting conditions.

[0046] [Table 2]

[0047] See the table below for detailed test results. [Table 3]

[0048] The test results show that the wear resistance and cutting edge toughness of the embodiment of the present invention are significantly improved compared to the comparative example when machining steel under continuous cutting conditions, which proves that the tool of the embodiment of the present invention can effectively improve the room temperature toughness and high temperature thermal vibration resistance of the material. [Explanation of symbols]

[0049] 1...First hard phase, 2...Second hard phase, 3...Solid solution strengthened binder phase, 4...Micro-nano precipitated phase

Claims

1. a hard phase, a binder phase, and tantalum and at least one element selected from the group consisting of niobium, manganese, ruthenium, rhenium, yttrium, and cerium added as a metal strengthener; the hard phase includes titanium carbonitride, tungsten, tantalum, and niobium carbides, molybdenum carbide, and at least one of molybdenum carbide and niobium carbide; A high-strength and tough cermet, characterized in that the binder phase comprises cobalt and nickel.

2. 2. The high-strength and toughness cermet according to claim 1, wherein the binder phase accounts for 10 to 24 wt % of the total amount of the cermet, and the hard phase accounts for 76 to 90 wt % of the total amount of the cermet.

3. 2. The high-strength and toughness cermet according to claim 1, wherein the grain size of the hard phase is 0.5 to 5.0 μm.

4. A cutting tool comprising a substrate made of the high-toughness cermet according to any one of claims 1 to 3.

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