Cermet and method for producing same, cutting tool

Abstract

The application relates to the field of cermet, in particular to cermet and a preparation method thereof and a cutting tool. The cermet comprises a hard phase and a binder phase, the first hard phase comprises first core-ring structure grains, the first core-ring structure grains comprise a first core and a first ring region surrounding at least part of the outer surface of the first core, and the material of the first core comprises Ti(C, N); the second hard phase comprises second core-ring structure grains, the second core-ring structure grains comprise a second core and a second ring region surrounding at least part of the outer surface of the second core, and the material of the second core comprises WC; wherein the aspect ratio of the first core-ring structure grains is 3-10; and the aspect ratio of the second core-ring structure grains is 2-6. The cermet effectively solves the problems of heat stress concentration and unstable sintering, and realizes the synchronization and significant improvement of toughness and thermal shock resistance.

Description

Technical Field

[0001] This application relates to the field of metal ceramics, and in particular to metal ceramics and their preparation methods, and cutting tools. Background Technology

[0002] Ceramic cermets, especially Ti(C,N)-based cermets, are widely used in machining applications due to their high hardness and good chemical stability. However, their inherently low toughness and poor thermal shock resistance limit their application in harsh conditions such as intermittent cutting.

[0003] Related technologies disclose methods for enhancing toughness by in-situ generation of Ti(C,N) whiskers. However, this approach still has significant drawbacks: First, the aspect ratio of Ti(C,N) whiskers is too high, making them prone to deformation, breakage, or overlap during sintering, making it difficult to obtain a stable and uniform microstructure; second, Ti(C,N) itself has a low thermal conductivity and a high coefficient of thermal expansion, resulting in poor thermal shock resistance of the material.

[0004] Therefore, there is an urgent need to develop a metal-ceramic material that can solve the above problems. Summary of the Invention

[0005] This application aims to at least partially address one of the technical problems in related technologies. To this end, this application proposes cermets and their preparation methods, as well as cutting tools. This application effectively solves the problems of thermal stress concentration and sintering instability by constructing a core-ring hard phase network of Ti(C,N) and WC.

[0006] A first aspect of this application provides a cermet. The cermet comprises a hard phase and a binder phase. The hard phase includes a first hard phase and a second hard phase. The first hard phase includes a first core-ring structure grain, each grain comprising a first core and a first ring region surrounding at least a portion of the outer surface of the first core. The first core is made of Ti(C,N). The second hard phase includes a second core-ring structure particle, each particle comprising a second core and a second ring region surrounding at least a portion of the outer surface of the second core. The second core is made of WC. The aspect ratio of the first core-ring structure grain is 3–10, and the aspect ratio of the second core-ring structure grain is 2–6. This application effectively solves the problem of thermal stress concentration caused by a single high aspect ratio Ti(C,N) whisker by constructing a "dual-core, dual-aspect-ratio" core-ring structure hard phase network comprising Ti(C,N) cores (aspect ratio 3–10) and WC cores (aspect ratio 2–6), significantly improving the uniformity of the microstructure.

[0007] According to an embodiment of this application, the hard phase further includes a third hard phase, which comprises acyclic TiCN grains.

[0008] According to embodiments of this application, the cermet further satisfies at least one of the following conditions: the material of the first ring region comprises a (Ti, W, Mo, M1)(C, N) solid solution, wherein M1 comprises at least one of Ta, Nb, V, Cr, and Zr; the material of the second ring region comprises a (Ti, W, Mo, M2)(C, N) solid solution, wherein M2 comprises at least one of Ta, Nb, V, Cr, and Zr; the binder phase comprises a high-entropy alloy, wherein the high-entropy alloy comprises at least one element selected from Co, Ni, Cu, Al, Fe, Cr, Mo, W, Ta, Nb, V, and Ti.

[0009] According to embodiments of this application, the cermet also satisfies at least one of the following conditions: the mass ratio of the hard phase to the binder phase is (80~85):(15~20); the quantity ratio of the first core-ring structure grains to the second core-ring structure grains is (1.8-2.2):1; the percentage of Cu atoms in the binder phase is 8%~12%, and the percentage of Al atoms is 18%~22%; the thickness of the ring region is 0.1μm~0.6μm; and the average grain size of the acyclic TiCN grains is 0.4μm~0.8μm.

[0010] According to embodiments of this application, the cermet satisfies at least one of the following conditions: fracture toughness K IC Not less than 10.5 MPa·m 1 / 2 The Rockwell hardness is not less than 91.0 HRA, and the transverse breaking strength is not less than 2500 MPa.

[0011] A second aspect of this application provides a method for preparing the aforementioned cermet, comprising: shear ball milling a first TiCN powder to obtain a precursor raw material, wherein the aspect ratio of the precursor raw material is 3-10; mixing the precursor raw material, a second TiCN powder, WC powder, a binder phase raw material, and an additive raw material, and then performing a second ball milling to obtain a mixture; subjecting the mixture to a molding process and a dewaxing process in sequence, and then sintering to obtain the cermet; wherein the additive raw material includes titanium ester organic compounds. This application obtains a slender strip structure by shear ball milling the first TiCN powder, and uses titanium ester organic compounds as additives to directionally induce WC powder to grow into plate-like grains with an aspect ratio of 2-6, achieving precise and independent control of the morphology of the two key hard phases, effectively improving the thermal shock resistance of the cermet, and obtaining a uniform and stable microstructure.

[0012] According to embodiments of this application, the method further satisfies at least one of the following conditions: the ester organic compound of titanium includes tetraisopropyl titanate; the ball-to-material ratio of the shear ball mill is (14-16):1, the revolution speed is 190 rpm-210 rpm, the rotation speed is 380 rpm-420 rpm, and the ball milling time is 2.5 h-3.5 h; the sintering is carried out in an inert atmosphere with a pressure of 3 mbar-6 mbar, the sintering temperature is 1480℃-1500℃, and the cooling atmosphere is an inert atmosphere of 3 MPa-7 MPa.

[0013] According to embodiments of this application, the method further satisfies at least one of the following conditions: the binder phase raw material includes powders of Co, Ni, Cu, and AlN; and the aluminum element in the binder phase is pre-alloyed and introduced in the form of AlN.

[0014] According to embodiments of this application, the method further satisfies at least one of the following conditions: the first TiCN powder has a Fisher particle size of 2.5 μm to 3.5 μm; the second TiCN powder has a Fisher particle size of 0.2 μm to 0.6 μm; the WC powder has a Fisher particle size of 0.4 μm to 1.2 μm; the mass ratio of the precursor raw material, the second TiCN powder, the WC powder, and the binder phase raw material is (9~13):(38.5~63):(14~21):(15~20); the molar ratio of Co, Ni, Cu, and Al in the binder phase raw material is (3.5~4.5):(1.5~2.5):1:(1.5~2.5); and the mass ratio of the additive raw material to the mixture is 1:(2000~50).

[0015] A third aspect of this application provides a cutting tool comprising the aforementioned cermet, or a cermet prepared by the method described above. This cutting tool possesses all the features and advantages of the aforementioned cermet and preparation method, which will not be elaborated upon here. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the SEM topography of one embodiment of this application; Reference numerals: 100: First hard phase; 200: Second hard phase; 300: Third hard phase; 400: Binding phase. Detailed Implementation

[0017] The embodiments described below are exemplary and intended to explain the present application, and should not be construed as limiting the present application.

[0018] In a first aspect, this application provides a metal-ceramic material comprising a hard phase and a binder phase. The hard phase includes a first hard phase and a second hard phase. The first hard phase includes a first core-ring structure grain, which includes a first core and a first ring region surrounding at least a portion of the outer surface of the first core. The material of the first core includes Ti(C,N). The second hard phase includes a second core-ring structure particle, which includes a second core and a second ring region surrounding at least a portion of the outer surface of the second core. The material of the second core includes WC. The aspect ratio of the first core-ring structure grain is 3 to 10, and the aspect ratio of the second core-ring structure grain is 2 to 6.

[0019] This application effectively solves the problem of thermal stress concentration caused by a single high aspect ratio Ti(C,N) whiskers by constructing a "dual-core, dual-aspect-ratio" core-ring hard phase network containing Ti(C,N) cores (aspect ratio 3–10) and WC cores (aspect ratio 2–6). The WC cores, with their high thermal conductivity and low coefficient of thermal expansion, effectively disperse and buffer thermal stress, acting as a "heat sink" to rapidly disperse heat flow and coordinate volume changes in the matrix under thermal shock, thereby significantly suppressing the initiation and propagation of hot cracks. It also avoids the sintering instability problems caused by using excessively high aspect ratio (>10) grains, significantly improving the uniformity of the microstructure.

[0020] Ceramic cermets are heterogeneous composite materials composed of a ceramic hard phase and a metal or alloy binder phase. The ceramic phase typically accounts for 15% to 85% of the volume fraction. Common hard phases include high-melting-point, high-hardness ceramics such as WC, TiC, Ti(C,N), Al2O3, TiN, and ZrB2. The binder phase is mostly transition metals or their alloys such as Co, Ni, Fe, Cr, and Mo. They are prepared through processes such as powder metallurgy (mixing, pressing, sintering), thermal spraying, laser cladding, sol-gel, and self-propagating high-temperature synthesis. Ceramic cermets combine the high temperature resistance, high hardness, wear resistance, oxidation resistance, and chemical stability of ceramics with the high toughness, machinability, good thermal conductivity, and thermal shock resistance of metals, while having a lower density. Due to these superior comprehensive properties, cermets have been widely used in high-end fields such as aerospace, machining, energy industry, automotive manufacturing, electronics, defense, and medical devices.

[0021] Core-ring structure is a typical characteristic microstructure in cermets. It refers to the "core-shell" spatial arrangement formed by hard ceramic phase particles ("core", such as WC, TiC, etc.) being covered by a continuous or semi-continuous carbonitride solid solution ("ring", such as (Ti,W,Mo) (C,N) etc.). This structure is usually formed during sintering due to the diffusion of hard phases such as carbides from the interface and "dissolution-precipitation" in liquid phase sintering. It bears the functions of transferring loads and hindering crack propagation. It is the core microstructure feature that determines the comprehensive mechanical properties of cermets, such as hardness, toughness and wear resistance. The thickness, continuity and uniformity of the ring layer directly affect the performance of the material.

[0022] The aspect ratio (L / D) of a core-ring structure refers to the ratio of the length of the ceramic hard phase particles constituting the "core" to their equivalent diameter. It is a key geometric parameter characterizing the morphology of ceramic particles in a core-ring structure. This parameter directly determines the coating method and uniformity of the solid solution "ring" on the surface of the ceramic particles: when the aspect ratio is close to 1 (near spherical), the solid solution ring can uniformly wrap the ceramic core, the core-ring interface is well bonded, the material is more isotropic, and the hardness is high, but the improvement in toughness is limited; when the aspect ratio increases (such as columnar or plate-shaped particles, where L / D can reach 2 to 5 or even higher), the contact area between ceramic particles increases, which is conducive to building a continuous hard skeleton network. The bridging effect of slender hard phase grains along the long axis of the particles is enhanced, the pull-out energy consumption increases, and the crack propagation needs to bypass a longer hard path, thus significantly improving the fracture toughness and bending strength of the material. However, it also increases the difficulty of uniformly coating the hard phase. If the ring layer is not uniformly distributed, stress concentration points are easily formed at the ends of the particles, which reduces the performance. Therefore, in typical metal-ceramic systems, adjusting the aspect ratio of the raw material powder and optimizing the uniformity of the core-ring structure in conjunction with the sintering process is one of the core methods to achieve the best match between hardness and toughness. The reasonable selection of the aspect ratio usually requires a balance between toughness gain and interface integrity.

[0023] According to embodiments of this application, the hard phase further includes a third hard phase, which comprises acyclic TiCN grains. By introducing a third hard phase—acyclic TiCN grains, i.e., TiCN ceramic particles whose surfaces are not covered by a solid solution phase and are directly exposed—into the cermet, these grains are dispersed in the matrix as "pure hard points" within the core-ring structure system. Since the acyclic TiCN grains do not have a relatively soft ring phase on their surface, their ultra-high hardness is fully preserved and directly participates in the friction and wear process, significantly increasing the material's high wear resistance.

[0024] According to an embodiment of this application, the material of the first ring region includes a (Ti, W, Mo, M1)(C, N) solid solution, wherein M1 includes at least one of Ta, Nb, V, Cr, and Zr; the material of the second ring region includes a (Ti, W, Mo, M2)(C, N) solid solution, wherein M2 includes at least one of Ta, Nb, V, Cr, and Zr. The first ring region and the second ring region have the same composition and structure, and their composition generally originates from the dissolution and precipitation process of carbide / carbonitride phases such as TiCN and WC during the liquid phase sintering stage. Multiple metallic elements, including W, Mo, Ta, Nb, V, Cr, and Zr, simultaneously dissolve into the Ti(C,N) lattice to form a substitutional solid solution. Due to the difference in atomic radii between each element and Ti, severe lattice distortion occurs, resulting in a strong solid solution strengthening effect, which significantly improves the hardness and wear resistance of the ring region. Secondly, the synergistic solid solution of multiple elements effectively reduces the difference in lattice constants between the ring region and the core region, enhancing the coherence of the core-ring interface, making the bonding tighter, and the ring layer coating more uniform and complete. This significantly improves the wettability between Ti(C,N) and metallic binder phases such as Ni and Co. The introduction of high-melting-point elements such as Ta and Nb significantly improves the high-temperature stability and oxidation resistance of the solid solution, enabling the material to maintain red hardness under harsh conditions such as high-temperature cutting. Meanwhile, elements such as V, Cr, and Zr help suppress the abnormal growth of hard phase grains during sintering, resulting in a finer and more uniform microstructure.

[0025] (Ti, W, Mo, M)(C, N) is a general chemical formula for a multi-component carbonitride solid solution. The first bracket (Ti, W, Mo, M) represents a metal cation sublattice, where four metal elements—Ti, W, Mo, and M (at least one of Ta, Nb, V, Cr, and Zr)—compete to occupy the same type of metal sites in the Ti(C,N) structure. Ti is the matrix element, while W, Mo, and M act as alloying additives, partially replacing Ti sites through substitution, forming a multi-component substitution solid solution with a metal sublattice. The second bracket (C, N) represents carbon and nitrogen, two non-metallic elements, competing to occupy the same type of anion sites in the structure, forming a CN mixed interstitial solid solution with arbitrary proportions. Overall, this formula describes a composite solid solution based on Ti(C,N), where metal sites are substituted by W / Mo / M multi-element substitution, and non-metallic sites are filled with a mixture of C and N.

[0026] According to embodiments of this application, the binder phase comprises a high-entropy alloy, which includes at least one element selected from Co, Ni, Cu, Al, Fe, Cr, Mo, W, Ta, Nb, V, and Ti. Using a high-entropy alloy of the aforementioned elements in the binder phase enables multi-objective synergistic optimization of hardness, toughness, and high-temperature stability, thereby improving the overall service performance of the cermet.

[0027] According to an embodiment of this application, the mass ratio of the hard phase to the binder phase is (80~85):(15~20), specifically 80:15, 81:16, 82:17, 83:18, 85:20 or any two of them. Within the above range, the continuous hard skeleton formed by the hard phase is guaranteed to provide extremely high hardness and excellent wear resistance, while the binder phase is sufficient to form a uniform and complete metal ring layer on the surface of the hard phase particles, ensuring strong bonding and efficient load transfer at the core-ring interface.

[0028] According to an embodiment of this application, the ratio of the number of the first core ring structure grains to the number of the second core ring structure grains is (1.8~2.2):1, specifically it can be 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1 or any two of them. Within the above ratio range, the second core ring and the first core ring can form a precisely matched "hard-tough" dual-core complementary system, achieving a balance between ultra-high hardness and high fracture toughness, while ensuring that the two types of core ring grains grow uniformly and competitively during sintering, resulting in a fine and dense structure.

[0029] The ratio of the number of the first core-ring structure grains to the number of the second core-ring structure grains is tested by the following method: in the secondary electron imaging mode of a field emission scanning electron microscope, a clear image is acquired in any field of view at a magnification of 3000x, the number of the first core-ring structure grains and the number of the second core-ring structure grains are counted respectively, and the ratio of the two is calculated.

[0030] According to an embodiment of this application, the thickness of the annular region is 0.1 μm to 0.6 μm, specifically 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm or any two of them. Within this thickness range, a good balance can be achieved between strengthening and toughening and avoiding interfacial brittle failure. At the same time, this thickness range is within the stable window of conventional liquid phase sintering process, which is beneficial to ensuring the uniformity and yield of the preparation.

[0031] According to embodiments of this application, the percentage of Cu atoms in the binder phase is 8% to 12%, specifically 8%, 9%, 10%, 11%, 12%, or any two of these ranges. These ranges can significantly improve the wettability of the binder phase to the hard phase.

[0032] According to embodiments of this application, the percentage of Al atoms in the binder phase is 18% to 22%, specifically 18%, 19%, 20%, 21%, 22%, or any combination thereof. Within this range, the high-temperature strength and red hardness of the cermet can be significantly improved.

[0033] According to the embodiments of this application, the average grain size of the acyclic TiCN grains is 0.4μm to 0.8μm, specifically 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm or any two of them. Within the above range, the abrasive wear resistance and adhesive wear resistance of the cermet can be significantly improved.

[0034] Acyclic TiCN grains are crystalline regions separated by grain boundaries in a continuous polycrystalline structure. They belong to the internal microstructure, and their average grain size can be determined according to GB / T 3488.3-2021.

[0035] According to embodiments of this application, the fracture toughness K of the metal-ceramic IC Not less than 10.5 MPa·m 1 / 2 This performance indicator shows that cermets possess excellent thermal shock resistance and a sufficiently high Kc. IC It can effectively inhibit crack initiation, is less prone to hot cracking due to thermal fatigue, and significantly extends the service life of metal ceramics.

[0036] According to the embodiments of this application, the metal has a Rockwell hardness of not less than 91.0 HRA. This performance index indicates that the surface of the metal ceramic has a very strong ability to resist local plastic indentation deformation. Under abrasive wear conditions, the hard phase particles are not easily scratched, cut or plowed off by abrasive particles, and the wear rate is extremely low.

[0037] According to the embodiments of this application, the transverse fracture strength of the metal ceramic is not less than 2500 MPa. This performance index indicates that the metal ceramic has extremely high bending load capacity when subjected to transverse loads, and is not prone to macroscopic fracture or plastic collapse under extreme working conditions, thus ensuring the structural integrity and safety of the metal ceramic.

[0038] A second aspect of this application provides a method for preparing the above-mentioned metal ceramic, comprising: S10: The first TiCN powder is shear-milled to obtain a precursor material with an aspect ratio of 3 to 10. Shear-milling the first TiCN powder can produce slender strip-shaped grains while minimizing lattice damage, thus preserving the high hardness and crystal integrity of the first TiCN powder to the maximum extent, which can serve as preferential nucleation and growth points in the subsequent sintering process.

[0039] According to an embodiment of this application, the shearing ball mill is carried out in a drum ball mill, where shearing ball milling combines the effects of shearing and impact. In the drum ball mill, the relative sliding between the grinding balls and the material generates strong shearing force, achieving planar layer-by-layer pulverization.

[0040] According to an embodiment of this application, the ball-to-powder ratio of the shearing ball mill is (14-16):1, specifically 14:1, 15:1, 16:1 or any two of them. Within the above range, it is ensured that each TiCN powder particle can be effectively captured by the milling balls and subjected to directional shearing and peeling force, maximizing the preservation of the integrity and high hardness of the first TiCN powder crystals, while the powder has good flowability and high uniformity, providing a precursor with uniform morphology for subsequent sintering.

[0041] According to an embodiment of this application, the revolution speed of the shearing ball mill is 190 rpm to 210 rpm, specifically 190 rpm, 195 rpm, 200 rpm, 205 rpm, 210 rpm or any two of them. Within the above range, the grinding balls slide down the tank wall and are thrown up again under the balance of gravity and centrifugal force, maintaining the maximum relative sliding speed with the first TiCN powder, generating the strongest macroscopic shear rate, so that the first TiCN powder particles are oriented and peeled into thin strips along the cleavage plane during repeated shearing and sliding.

[0042] According to an embodiment of this application, the rotation speed of the shearing ball mill is 380 rpm to 420 rpm, specifically 380 rpm, 385 rpm, 390 rpm, 395 rpm, 400 rpm, 405 rpm, 410 rpm, 415 rpm, 420 rpm or any two of them. Within the above range, the collision energy between the grinding balls can be controlled below the threshold that does not damage the elongated strip shape, ensuring that the formed elongated strip is not broken.

[0043] According to an embodiment of this application, the ball milling time of the shearing ball mill is 2.5h to 3.5h, specifically 2.5h, 3h, 3.5h or any two of them. Within the above ball milling time range, it is possible to ensure that the first TiCN powder has high activity, which is conducive to sintering and densification, without reducing hardness due to excessive damage.

[0044] According to the embodiments of this application, the aspect ratio of the precursor raw material is 3 to 10, specifically 3, 4, 5, 6, 7, 8, 9, 10 or any two of them. Within this range, the precursor raw material can have both high packing density and sufficient contact area during sintering, which is conducive to the uniform penetration of liquid phase between particles and the directional dissolution-diffusion of solute atoms, and helps to improve the uniformity of the structure.

[0045] According to an embodiment of this application, the Fisher particle size of the first TiCN powder is 2.5 μm to 3.5 μm, specifically 2.5 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.5 μm or any two of them. Within the above particle size range, the shear stress applied by the grinding ball is concentrated in a local area on the surface of the first TiCN powder, resulting in directional peeling rather than overall pulverization, and the first TiCN powder is transformed into a thin strip.

[0046] S20: The precursor raw material, second TiCN powder, WC powder, binder phase raw material, and additive raw material are mixed and then subjected to a second ball milling to obtain a mixture. This step ensures that the powders and raw materials are fully mixed, eliminates particle size and component segregation, and ensures uniform distribution.

[0047] According to an embodiment of this application, the Fisher particle size of the second TiCN powder is 0.2μm to 0.6μm, specifically 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm or any two of them. Within the above range, high strength at the interface of the core-ring structure can be guaranteed, ensuring efficient load transfer between the first core-ring structure and the bonding phase, and effectively deflecting cracks and bridging crack propagation.

[0048] According to an embodiment of this application, the Fisher particle size of the WC powder is 0.4μm to 1.2μm, specifically it can be 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm or any two of them. Within the above range, the powder achieves the densest packing of large powder particles to support the skeleton and small powder particles to fill the gaps, thereby reducing porosity.

[0049] The Fisher particle size of the first TiCN powder, the second TiCN powder, and the WC powder was tested according to GB / T 3249-2009. The steady-flow air permeation method was used. Under constant airflow velocity and pressure, the external specific surface area of ​​the powder was calculated by measuring the pressure drop when dry air permeated through the compacted powder layer, and then converted into Fisher particle size. The measurement range was 0.5 μm to 50 μm. For the test, 10 g of dried powder sample was taken. First, one sample was compacted and measured sequentially at porosity intervals of 0.005 to 0.05, starting from a higher porosity, until it could not be compacted further. The average porosity corresponding to the two closest adjacent particle size values ​​was taken as the optimal porosity. Then, another sample was taken and subjected to a pressure of 222 N at this optimal porosity for formal measurement. The Fisher particle size was read from the U-tube manometer reading and then read through a particle size reading plate.

[0050] According to an embodiment of this application, the mass ratio of the precursor raw material, the second TiCN powder, the WC powder, and the binder phase raw material is (9~13):(38.5~63):(14~21):(15~20), specifically 9:38.5:14:15, 10:48:16:16, 11:50:18:19, 12:55:20:20, 13:63:21:20, or any two of these ranges. Within the above range, the binder phase is sufficient to fill the pores and achieve good bonding. Under synergistic effect, the material can form a complete core-ring structure after sintering, thereby simultaneously improving transverse fracture toughness and bending strength.

[0051] According to an embodiment of this application, the molar ratio of Co, Ni, Cu, and Al in the binder phase raw material is (3.5-4.5): (1.5-2.5): 1: (1.5-2.5), specifically it can be 3.5:1.5:1:1.5, 4:2:1:2, 4.5:2.5:1:2.5 or any two of them. Within the above range, the binder phase has high wettability, high density, high strength and oxidation resistance.

[0052] According to an embodiment of this application, the mass ratio of the additive raw material to the mixture is 1:(2000-50), specifically it can be 1:2000, 1:1500, 1:1000, 1:500, 1:100, 1:50 or any two of them. Within the above range, it can suppress grain coarsening, maintain a uniform fine-grained structure, and at the same time not impair the strength and toughness of the binder phase.

[0053] According to an embodiment of this application, the binder phase raw material includes powders of Co, Ni, Cu, and AlN, with Co having the highest proportion, providing core binding force for WC powder and ensuring that the WC skeleton is fully wetted and coated. Cu provides a sintering liquid phase, enhancing the solid solution strengthening effect of carbonitrides.

[0054] According to embodiments of this application, the aluminum element in the binder phase is pre-alloyed and introduced in the form of AlN. The introduction of AlN instead of metallic Al results in high chemical stability, no oxidation or deactivation during ball milling and storage, and superior dispersion uniformity.

[0055] AlN is a covalent compound with high chemical stability. It does not oxidize or deactivate during ball milling and storage, ensuring complete Al retention. However, it is also hard and brittle, easily crumbling during ball milling. Its mixing uniformity with WC powder, precursor materials, and second TiCN powder is far superior to that of metallic Al. During sintering, AlN gradually decomposes in the Cu liquid phase, releasing Al at the atomic level and diffusing into the Co-Ni-Cu binder phase. Simultaneously, the N atoms released from AlN decomposition dissolve into the TiCN lattice to form a Ti(C,N) solid solution, further enhancing the carbonitride solid solution strengthening and oxidation resistance.

[0056] According to an embodiment of this application, the mixing is carried out in a drum ball mill with a ball-to-material ratio of (2.5 to 3.5):1, specifically 2.5:1, 3:1, 3.5:1 or any two of them. The ball-to-material ratio within the above range is sufficient to fully pulverize AlN and drive it to uniformly pre-coat the surface of the hard phase, while protecting the hard phase from decarburization, thus laying a uniform microstructure foundation for the gradient wetting system during sintering.

[0057] According to an embodiment of this application, the mixing uses alcohol as a medium. Alcohol has low surface tension and excellent wettability. Alcohol is much less polar than water, which can significantly inhibit the cold welding agglomeration of Co, Ni, and Cu metal powders during ball milling. In addition, alcohol evaporates quickly, leaving no residue after drying and not introducing impurities.

[0058] According to an embodiment of this application, the liquid-to-solid ratio of the mixture is 350 ml / kg to 450 ml / kg, specifically 350 ml / kg, 360 ml / kg, 370 ml / kg, 380 ml / kg, 390 ml / kg, 400 ml / kg, 410 ml / kg, 420 ml / kg, 430 ml / kg, 440 ml / kg, 450 ml / kg or any two of these ranges. Within this range, the alcohol adequately lubricates the contact surface between the grinding balls and the mixture, ensuring efficient transmission of shear force and obtaining a mixture with suitable viscosity.

[0059] According to an embodiment of this application, the mixing speed is 45 rpm to 55 rpm, specifically 45 rpm, 46 rpm, 47 rpm, 48 rpm, 49 rpm, 50 rpm, 51 rpm, 52 rpm, 53 rpm, 54 rpm, 55 rpm or any two of them. The grinding balls inside the drum are in the optimal drop-rolling state, and the grinding balls fully collide with the mixed powder to obtain a mixture with a suitable viscosity.

[0060] According to an embodiment of this application, the mixing time is 3.5h to 4.5h, specifically 3.5h, 4h, 4.5h or any two of them. Within the above range, the mixture can be fully broken down to obtain a mixture with suitable viscosity.

[0061] According to embodiments of this application, the additive raw material includes titanium ester organic compounds. Titanium ester organic compounds can decompose during sintering, and their decomposition products selectively adsorb onto the (0001) facet of WC powder grains, inhibiting their excessively rapid growth along that direction, thereby directionally inducing their growth into plate-like grains with an aspect ratio of 2 to 6.

[0062] According to an embodiment of this application, the ester organic compound of titanium includes tetraisopropyl titanate, which can decompose during sintering. Its decomposition products can selectively adsorb onto the (0001) face of WC grains, inhibiting their excessive growth along that direction, thereby directionally inducing their growth into plate-shaped grains with an aspect ratio of 2 to 6.

[0063] S30: The mixture is subjected to molding and dewaxing processes in sequence, followed by sintering to obtain a metal ceramic. Shearing and ball milling yield a uniform mixture. Molding ensures a uniform, dense, and defect-free green body. Dewaxing ensures complete evaporation of the alcohol medium, leaving no residual carbon and zero binder residue, thus avoiding sintering porosity sources. After sintering, a high-performance metal ceramic with a core-ring structure is obtained.

[0064] The forming process involves applying pressure to a mold through processes such as pressing the uniformly mixed powder obtained by ball milling, causing the powder particles to rearrange, fill, and solidify into a green body with a specific geometry and sufficient green strength. Its purpose is to give the mixed green body precise external dimensions, while the pressure makes the hard phase and binder phase powders come into close contact, providing sufficient green strength to meet the requirements of subsequent dewaxing and sintering, thus laying the foundation for high-density, high-performance metal ceramics.

[0065] Dewaxing is a heat treatment process in which a green body containing wax-based binder is slowly heated to above the melting point of the binder under controlled heating rate. This process melts, volatilizes, and completely removes the waxy organic matter from the green body. Its purpose is to completely remove the molded material, avoid residual carbon, and prevent the formation of pores during sintering. At the same time, because the alcohol medium itself evaporates completely without leaving any liquid residue, the green body shrinks evenly during dewaxing without cracking or deformation. Finally, a clean green body without organic residue is obtained, ensuring that it is not affected by carbon during sintering.

[0066] According to embodiments of this application, the binder phase is a high-entropy alloy binder phase, which is a solid solution alloy formed by mixing five or more main metallic elements (such as Co, Cr, Fe, Ni, Al, Mo, Cu, etc.) in equimolar or near-equimolar ratios. The high-entropy effect reduces the Gibbs free energy of the system, inhibits the formation of intermetallic compounds, and promotes the stable existence of a single solid solution phase. Simultaneously, the difference in atomic radii among the components leads to severe lattice distortion, resulting in strong solid solution strengthening, accompanied by a hysteresis diffusion effect that effectively suppresses grain coarsening and interfacial reactions in the hard phase. This binder phase integrates the wetting properties of each component through a "cocktail effect," exhibiting excellent wetting and filling capabilities for hard phases such as WC and Ti(C,N). Replacing the traditional Co / Ni binder phase, it significantly improves the material's hardness, fracture toughness, high-temperature oxidation resistance, and corrosion resistance while lowering the sintering temperature and refining the grain structure, making it a key binder phase for achieving the goals of this application.

[0067] According to an embodiment of this application, the sintering is carried out in an inert atmosphere with a pressure of 3 mbar to 6 mbar. Specifically, the pressure can be 3 mbar, 4 mbar, 5 mbar, 6 mbar or any two of them. This pressure range is low vacuum sintering, which allows the N2 and other gases generated by AlN decomposition to escape smoothly and suppresses the evaporation loss of Co, Ni and Cu binder phases.

[0068] According to the embodiments of this application, the sintering temperature is 1480℃~1500℃, specifically 1480℃, 1490℃, 1500℃ or any two of them. Within the above temperature range, AlN fully decomposes and releases active Al, simultaneously driving Co to wet WC powder, Ni to wet the first TiCN powder and the second TiCN powder, and Cu to fully melt and flow to fill the residual pores, taking into account both wetting integrity and microstructure fineness, to obtain a high-density metal ceramic.

[0069] According to the embodiments of this application, the cooling atmosphere is an inert atmosphere of 3MPa to 7MPa, specifically 3MPa, 4MPa, 5MPa, 6MPa, 7MPa or any two of them. Within this pressure range, the high-pressure inert atmosphere can effectively suppress the evaporation loss of Co, Ni and Cu binder phases in the high-temperature range, reduce thermal stress, balance composition preservation and economy, and is conducive to obtaining high-performance metal ceramics with stable composition.

[0070] According to the embodiments of this application, the inert atmosphere includes at least one of argon and helium. This step does not specifically limit the type and volume fraction of the inert atmosphere, as long as it provides a chemically stable protective environment for the sintering process and the cooling process after sintering, preventing oxidation, pollution and side reactions. The specific choice can be made flexibly according to the actual situation.

[0071] An inert atmosphere isolates oxygen throughout the sintering and cooling process, preventing decarburization of WC powder, oxidation of the first TiCN powder and the second TiCN powder, and oxidation and deactivation of the Co, Ni, and Cu binder phases. This ensures that the active Al atoms generated by AlN decomposition are not oxidized and consumed, while allowing gases such as N2 released by AlN decomposition to escape smoothly from the green body, avoiding the formation of closed pores. This helps maintain the compositional stability of the cermet and reduces the occurrence of side reactions.

[0072] According to embodiments of this application, the metal-ceramic reference prepared by the above method... Figure 1As shown, scanning electron microscopy (SEM) observations revealed that the cermet exhibits a multiphase gradient distribution structure: the first hard phase 100 consists of Ti(C,N) grains with a "black core-gray ring" characteristic, where the black core is a Ti(C,N) nucleus and the gray ring is a (Ti, W, Mo, M1)(C, N) solid solution; the second hard phase 200 consists of WC grains with a "bright core-gray ring" characteristic, where the bright white core is a WC nucleus and the gray ring is a (Ti, W, Mo, M2)(C, N) solid solution; the third hard phase 300 consists of spherical TiCN grains without encapsulating rings, uniformly dispersed in the matrix; the grains of each hard phase are connected and filled by a binder phase 400, forming a dense core-ring structure.

[0073] In a third aspect, this application provides a cutting tool comprising the aforementioned cermet, or a cermet prepared by the method described above. This cutting tool possesses all the advantages and features of the aforementioned cermet and preparation method, which will not be elaborated upon here.

[0074] This application has at least the following beneficial effects: 1. Achieved a significant synergistic improvement in toughness and thermal shock resistance: This invention effectively solves the problem of thermal stress concentration caused by a single high aspect ratio Ti(C,N) whisker by constructing a "dual-core, dual-aspect-ratio" core-ring hard phase network containing a Ti(C,N) core (aspect ratio 3-10) and a WC core (aspect ratio 2-6). The WC core has high thermal conductivity (~110 W / (m·K)) and a low coefficient of thermal expansion (~4.5×10⁻⁶). -6 ( / ℃), which can effectively disperse and buffer thermal stress, becoming a "heat sink" for rapidly dispersing heat flow, coordinating the volume change of the matrix under thermal shock, and thus significantly inhibiting the initiation and propagation of thermal cracks.

[0075] 2. A stable microstructure with excellent interfaces was obtained: This invention avoids the sintering instability caused by using excessively high aspect ratios (>10) grains by controlling the aspect ratio of Ti(C,N) core grains to 3-10 and the aspect ratio of WC core grains to 2-6, thus significantly improving the uniformity of the microstructure. Simultaneously, the binder phases with specific compositions (Cu 8-12 at%) and Al 18-22 at%) exhibit excellent wettability and interfacial bonding strength for both the Ti(C,N)-based and WC-based hard phases. A strong and tough metallurgical interface is formed between the three hard phases and the binder phase, ensuring effective load transfer and overall material strength and toughness.

[0076] 3. A controllable and effective preparation method is provided: This invention achieves precise and independent control of the morphology of two key hard phases through a combination of "high-energy ball milling to prepare the precursor" and "addition of titanium ester organics". The precursor raw material prepared by high-energy ball milling is rich in defects and strain, which can serve as the preferred nucleation and growth point for Ti(C,N) core grains (second hard phase) during subsequent sintering. The titanium ester organics (preferably tetraisopropyl titanate) decompose during sintering, and their decomposition products are selectively adsorbed on the (0001) surface of WC grains, inhibiting their excessively rapid growth along this direction, thereby directionally inducing their growth into plate-shaped grains with an aspect ratio of 2 to 6 (third hard phase).

[0077] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0078] The embodiments of this application are described in detail below: Example 1 (1) Preparation of precursor: TiCN powder with a Fisher particle size of 2.98 μm was ball-milled for 3 hours in a QM-QX8L planetary ball mill at a ball-to-material ratio of 15:1, a revolution speed of 200 rpm and a rotation speed of 400 rpm to obtain precursor raw materials.

[0079] (2) Mixing: The mixture was prepared according to the following weight percentages: 10% precursor raw material, 56% TiCN powder with a Fisher particle size of 0.55 μm, 15% WC powder with a Fisher particle size of 0.78 μm, 15% binder phase raw material B (binder phase raw material B is prepared from elemental powders of Co, Ni, Cu and AlN in a molar ratio of Co:Ni:Cu:Al:Cr = 4:2:1:2:1), 3% TaC powder (Fischer particle size of 1.38 μm), 0.5% Mo2C powder (Fischer particle size of 1.78 μm), and 0.5% tetraisopropyl titanate. 4% paraffin molding agent was added based on the total mass of the mixture. The above mixture was placed in a drum ball mill and wet-milled for 4 hours at a ball-to-material ratio of 3:1, a liquid-to-solid ratio of 400 ml / kg alcohol, and a rotation speed of 50 rpm. After drying, the mixture was obtained.

[0080] (3) Sintering: The mixture is made into a compact and placed in a sintering furnace. After vacuum dewaxing, it is sintered at 1490℃ in an argon atmosphere of 5 mbar. Then it is cooled to room temperature under an argon pressure of 5 MPa to obtain a metal ceramic sample.

[0081] Example 2 Prepared according to the method of Example 1, with the following differences: the amount of precursor raw material is 12%, the amount of second TiCN powder is 43.5%, the amount of WC powder is 20%, the amount of binder raw material is 15%, the amount of Mo2C powder is 0.5%, NbC powder (Fairwood particle size of 1.22 μm) is used to replace TaC at an amount of 8%, and the amount of tetraisopropyl titanate is 1%.

[0082] Example 3 Prepared according to the method of Example 1, with the following differences: the amount of precursor raw material is 12%, the amount of second TiCN powder is 38.5%, the amount of WC powder is 20%, the binder phase raw material is prepared according to the molar ratio of Co:Ni:Cu:Al:Mo = 4.5:1.5:1:1.5:1, the amount is 20%, Mo2C powder is 0.5%, TaNbC powder (Fairwood particle size is 1.33 μm) is used instead of TaC, the amount is 8%, and the amount of tetraisopropyl titanate is adjusted to 1%.

[0083] Example 4 Prepared according to the method of Example 1, with the following differences: the amount of precursor raw material is 12%, the amount of second TiCN powder is 43.5%, the amount of WC powder is 20%, the amount of binder phase raw material is prepared according to the molar ratio of Co:Ni:Cu:Al = 4.5:1.5:1.5:1 (without adding Cr or Mo) is 20%, Mo2C powder is 0.5%, VC powder (Fairwood particle size is 1.42 μm) is used instead of TaC powder, the amount is 1%, Cr3C2 powder (Fairwood particle size is 1.25 μm) is 2%, and the amount of tetraisopropyl titanate is adjusted to 1%.

[0084] Comparative Example 1 Prepared according to the method of Example 1, the difference being that: a traditional Co / Ni binder phase (Co:Ni=1:1) was used instead of the binder phase in Example 1, no precursor raw materials were added, and tetraisopropyl titanate was not added. The ingredients were: 66.5% TiCN powder, 15% WC powder, 15% Co / Ni binder phase, 3% TaC, and 0.5% Mo2C. 4% paraffin molding agent was then added based on the total mass of the ingredients.

[0085] Comparative Example 2 Prepared according to the method of Comparative Example 1, the difference being: the amount of second TiCN powder is 56.5%, the amount of WC powder is 20%, the amount of Co / Ni binder phase is 15%, the amount of NbC is 8%, and the amount of Mo2C is 0.5%.

[0086] Comparative Example 3 Prepared according to the method of Comparative Example 1, the difference being: the amount of second TiCN powder is 51.5%, the amount of WC powder is 20%, the amount of Co / Ni binder phase is 20%, the amount of TaNbC is 8%, and the amount of Mo2C is 0.5%.

[0087] Comparative Example 4 Prepared according to the method of Comparative Example 1, the difference being: the amount of second TiCN powder is 56.5%, the amount of WC powder is 20%, the amount of Co / Ni binder phase is 20%, the amount of VC is 1%, the amount of Cr3C2 is 2%, and the amount of Mo2C is 0.5%.

[0088] Test methods (1) Hardness test: The hardness of the sample was determined by Rockwell hardness tester under HRA scale according to GB / T 230.1-2018 standard. A 120° diamond cone indenter (tip radius 0.2mm) was used to press into the sample surface under two loads: initial test force 98N (held for 1s) and total test force 588.4N (held for 4s). After the main test force was removed, the residual indentation depth was read under the initial test force and the HRA value was calculated. Five test points were taken on a flat and smooth surface ≥2.5mm from the edge of each sample. The center distance between adjacent indentations was ≥2.5mm. After independent measurement at each point, outliers were removed. The arithmetic mean of the valid data was taken as the HRA hardness value of the sample. The test environment temperature was controlled at 25℃. The instrument was calibrated with a standard hardness block before the test. The test could only be carried out if the deviation and repeatability were within the allowable range.

[0089] (2) Fracture toughness test: The transverse fracture toughness K was determined by indentation method (IM) according to GB / T 23806-2025. IC The test was conducted on a Vickers hardness tester. A 10 kgf load was applied for 15 seconds and then unloaded. The half-crack length c (μm) from the center of the indentation to the crack tip and the half-length a (μm) of the indentation diagonal were then measured under an optical microscope. c / a was required to meet the Palmqvist crack criterion. K IC Calculated according to the Anstis formula:

[0090] Where K IC Fracture toughness, in MPa·m 1 / 2 E represents the elastic modulus in GPa, H represents the Vickers hardness in GPa, P represents the indentation load in N, and c represents the half-crack length in μm. At least 5 effective indentations should be made for each sample group. After removing outliers, the arithmetic mean should be taken as the final K. IC result.

[0091] (3) Thermal shock resistance test: First, a pre-made crack was pressed into the polished surface of the sample (Ra≤0.5μm) on a Vickers hardness tester with a load of 10 kgf. The initial crack half length L0 was measured under a scanning electron microscope (the average value of four cracks was taken, and the measurement accuracy was ±1μm). Then, the sample was placed in a programmable temperature controlled muffle furnace and heated to 250℃±5℃ at a heating rate of ≤5℃ / min. The sample was held for 10 min to make the internal and external temperatures uniform. After being removed, the sample was quickly quenched into deionized water at 25℃ within 2 s. The water temperature fluctuation was controlled within ±2℃, and the sample was kept in the water for no more than 5 minutes. After s, remove and wipe off the surface moisture. This is one thermal shock cycle. Repeat 15 times. After 15 cycles, measure the final crack half length L and calculate the crack extension rate as (L-L0) / L0×100%. At least 3 parallel specimens are tested for each sample. The average value is taken as the thermal shock resistance index of the material. The lower the crack extension rate, the stronger the material's ability to resist thermal shock crack propagation and the better its thermal shock resistance.

[0092] The test results are shown in the table below: Table 1

[0093] Table 2

[0094] Results analysis: (1) Hardness: The HRA hardness of Examples 1-4 of this application is 91.6-92.2, while that of Comparative Examples 1-4 is 91.9-92.3. The two are comparable, indicating that this application does not differ significantly from the prior art in maintaining high hardness. The technical problem to be solved by this application is not simply to maximize hardness. As is well known, hardness and toughness are a pair of contradictory properties, and improving toughness often comes at the cost of hardness. The purpose of this application is to effectively improve the toughness and thermal shock resistance of the material without excessively sacrificing hardness (i.e., maintaining a high hardness level). Therefore, the technical effect of this application is reflected in the comprehensive balance and optimization of hardness and toughness, rather than the improvement of a single hardness index. Accordingly, the hardness value of the examples does not need to be higher than that of the comparative examples. As long as the hardness is maintained at a high level and the toughness and thermal shock resistance are significantly improved compared with the comparative examples, the realization of the technical effect of this application can be confirmed.

[0095] (2) Fracture toughness: K in Examples 1-4 of this application IC The values ​​reached 10.5–10.9 MPa·m¹ / ², which is much higher than the 7.9–9.1 MPa·m¹ / ² of Comparative Examples 1–4. This indicates that the present application significantly improved the fracture toughness of the material by constructing a core-ring hard phase network with a "dual core and dual aspect ratio".

[0096] (3) Regarding thermal shock resistance: The crack elongation rate of Examples 1-4 of this application after 15 cycles of water quenching and thermal shock at 250℃ was only 38.4% to 42.1%, while that of Comparative Examples 1-4 was as high as 60.4% to 87.3%. In particular, Comparative Example 4, although it had the highest hardness (92.3 HRA), had the worst toughness (7.9 MPa·m¹ / ²) and the worst thermal shock resistance (crack elongation rate of 87.3%), which fully demonstrates the contradiction between improved toughness and decreased thermal shock resistance in traditional technologies. However, the examples of this application significantly improved both toughness and thermal shock resistance, achieving a synergistic improvement in both.

[0097] (4) Comparative analysis: Comparative examples 1-4 did not adopt the core features of this application (dual-core hard phase, binder phase, titanium ester induced process). Although they could maintain high hardness, their toughness and thermal shock resistance were far inferior to the embodiments of this application.

[0098] In summary, this application successfully provides a metal-ceramic material that combines high hardness, high toughness, and excellent thermal shock resistance. Its preparation method is stable and controllable, and has significant industrial application value.

[0099] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0100] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above 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 one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0101] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A metal-ceramic compound, characterized in that, It includes a hard phase and a binder phase, wherein the hard phase includes a first hard phase and a second hard phase; The first hard phase includes a first core-ring structure grain, the first core-ring structure grain includes a first core and a first ring region surrounding at least a portion of the outer surface of the first core, the material of the first core includes Ti(C,N); The second hard phase includes a second core-ring structure particle, the second core-ring structure particle includes a second core and a second ring region surrounding at least a portion of the outer surface of the second core, the material of the second core includes WC; The aspect ratio of the first core-ring structure grain is 3 to 10; the aspect ratio of the second core-ring structure grain is 2 to 6.

2. The metal ceramic according to claim 1, characterized in that, The hard phase further includes a third hard phase, which comprises acyclic TiCN grains.

3. The metal ceramic according to claim 1, characterized in that, It also meets at least one of the following conditions: The material of the first ring region includes a (Ti, W, Mo, M1)(C, N) solid solution, wherein M1 includes at least one of Ta, Nb, V, Cr, and Zr; The material of the second ring region includes a (Ti, W, Mo, M2)(C, N) solid solution, wherein M2 includes at least one of Ta, Nb, V, Cr, and Zr; The binder phase comprises a high-entropy alloy, which includes at least one element selected from Co, Ni, Cu, Al, Fe, Cr, Mo, W, Ta, Nb, V, and Ti.

4. The metal ceramic according to claim 2, characterized in that, It also meets at least one of the following conditions: The mass ratio of the hard phase to the binder phase is (80~85):(15~20); The ratio of the number of the first core-ring structure grains to the number of the second core-ring structure grains is (1.8-2.2):1; The binder phase contains 8%–12% Cu atoms and 18%–22% Al atoms. The thickness of the annular region is 0.1 μm to 0.6 μm; The average grain size of the acyclic TiCN grains is 0.4 μm to 0.8 μm.

5. The metal ceramic according to claim 1, characterized in that, At least one of the following conditions must be met: fracture toughness K IC Not less than 10.5 MPa·m 1 / 2 , Rockwell hardness not less than 91.0 HRA The transverse fracture strength is not less than 2500 MPa.

6. A method for preparing a cermet as described in any one of claims 1-5, characterized in that, include: The first TiCN powder is shear-milled to obtain a precursor raw material, wherein the aspect ratio of the precursor raw material is 3 to 10. The precursor raw material, the second TiCN powder, the WC powder, the binder phase raw material, and the additive raw material are mixed and then subjected to a second ball milling to obtain a mixture. The mixture is subjected to molding and dewaxing processes in sequence, followed by sintering to obtain a metal ceramic. The additive raw materials include titanium ester organic compounds.

7. The method according to claim 6, characterized in that, It also meets at least one of the following conditions: The ester organic compounds of titanium include tetraisopropyl titanate; The ball-to-material ratio of the shear ball mill is (14-16):1, the revolution speed is 190 rpm-210 rpm, the rotation speed is 380 rpm-420 rpm, and the ball milling time is 2.5h-3.5h. The sintering is carried out in an inert atmosphere with a pressure of 3 mbar to 6 mbar, a sintering temperature of 1480℃ to 1500℃, and a cooling atmosphere of 3 MPa to 7 MPa.

8. The method according to claim 6, characterized in that, It also meets at least one of the following conditions: The binder phase raw materials include powders of Co, Ni, Cu, and AlN; The aluminum element in the binder phase is introduced in the form of AlN through pre-alloying.

9. The method according to claim 6, characterized in that, It also meets at least one of the following conditions: The first TiCN powder has a Fisher particle size of 2.5 μm to 3.5 μm; The second TiCN powder has a Fisher particle size of 0.2 μm to 0.6 μm; The WC powder has a Fisher particle size of 0.4 μm to 1.2 μm; The mass ratio of the precursor raw material, the second TiCN powder, the WC powder, and the binder phase raw material is (9~13):(38.5~63):(14~21):(15~20); The molar ratio of Co, Ni, Cu, and Al in the binder phase raw material is (3.5–4.5): (1.5–2.5): 1: (1.5–2.5); The mass ratio of the additive raw material to the mixture is 1:(2000-50).

10. A cutting tool, characterized in that, The metal ceramics include those described in any one of claims 1 to 5, or those prepared by the method described in any one of claims 6 to 9.

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