Cemented carbide, method for producing cemented carbide and use of cemented carbide

Abstract

The application discloses a cemented carbide and a preparation method and application thereof. The cemented carbide comprises a hard phase, a metal binder phase and an eta phase. The eta phase is a carbide, and the equivalent particle diameter of the eta phase is 10 nm to 200 nm. The volume fraction of the eta phase is 1% to 8% based on the total volume of the cemented carbide. At least 70% of the eta phase particles are distributed in the interface region of the hard phase and the metal binder phase in a dispersed state based on the total volume of the eta phase. Thus, the cemented carbide provided by the application has good hardness and toughness.

Description

Technical Field

[0001] This application relates to the field of alloy technology, specifically to a cemented carbide, its preparation method, and its application. Background Technology

[0002] Cemented carbide typically consists of a hard phase and a metallic binder phase, and its properties are significantly influenced by carbon content, binder phase composition, and microstructure. Under conditions of low carbon content or localized carbon deficiency, the η phase is easily formed in cemented carbide. Traditionally, the η phase is generally considered a brittle and harmful phase resulting from decarburization. In conventional sintering processes, carbon deficiency-induced η phases often exhibit coarse (typically micrometer-sized), dendritic, or continuous network structures. This morphology of the η phase severely disrupts the continuity of the binder phase, becoming a stress concentration source, leading to a significant decrease in the fracture toughness of the cemented carbide and making it highly susceptible to tool chipping. Therefore, current technologies generally strive to avoid the formation of the η phase. However, by precisely controlling the formation path, size, and distribution of the η phase, allowing it to exist in a fine, dispersed form, the η phase can potentially be transformed into an effective "strengthening phase," significantly improving the high-temperature strength and resistance to plastic deformation of the alloy without significantly reducing toughness. However, the formation process of the η phase is uncontrollable. Therefore, how to refine the size of the η phase and achieve a uniform and dispersed distribution of the η phase, so as to balance the hardness and toughness of cemented carbide, has become an urgent technical problem to be solved.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of this application, a cemented carbide is provided, comprising a hard phase, a metallic binder phase, and an η phase; The η phase is a carbide, and the equivalent particle size of the η phase is 10 nm to 200 nm. Based on the total volume of the cemented carbide, the volume fraction of the η phase is 1% to 8%; Based on the total volume of the η phase, at least 70% of the η phase particles are distributed in a dispersed state at the interface region between the hard phase and the metal bonding phase.

[0005] Therefore, the cemented carbide provided in this application possesses both high hardness and toughness, with a hardness HV30 ≥ 1486 and a fracture toughness ≥ 14.2 MPa·m. 1 / 2 This achieves an excellent balance between hardness and toughness.

[0006] In some embodiments of this application, the cemented carbide satisfies at least one of the following conditions: (1) The hard phase includes WC; (2) The metal binder phase includes at least one of Co and Ni.

[0007] This is beneficial for further improving the hardness and toughness of cemented carbide.

[0008] In some embodiments of this application, the η phase includes M6C, M 12 At least one of C-type carbides; wherein the M element includes at least one of W, Co, and Ni. Therefore, M6C, M... 12 C-type carbides possess a dense crystalline structure and high intrinsic hardness, allowing them to be finely dispersed in the microstructure of cemented carbides. They achieve grain refinement and dispersion strengthening by pinning grain boundaries and hindering dislocation movement. At the same time, they exhibit good thermodynamic stability and strong microstructure adaptability, making it easy to control the carbon balance and microstructure of the alloy. This improves the hardness, wear resistance, and high-temperature stability of the alloy while reducing the continuous precipitation of brittle phases, thus giving cemented carbides good strength and toughness.

[0009] In some embodiments of this application, the shape of the η-phase particles includes quasi-spherical and / or ellipsoidal, and / or the aspect ratio of the η-phase particles is 1 to 2. This facilitates the uniform dispersion of the η-phase particles in the interface region, reduces stress concentration, and improves the toughness of the cemented carbide.

[0010] In some embodiments of this application, the cemented carbide satisfies at least one of the following conditions: (1) The coercivity of the hard alloy is 100 Oe to 250 Oe; (2) The average grain size of the hard phase particles is 0.6 μm to 2 μm; (3) The equivalent particle size of the η phase is 10nm~100nm; preferably, the equivalent particle size of the η phase is 38nm~72nm.

[0011] This is beneficial for further improving the hardness and toughness of cemented carbide.

[0012] In some embodiments of this application, the mass percentage of the metal binder phase is 8% to 15% based on the total mass of the cemented carbide, and / or the mass percentage of the n-phase is 2% to 10%. This is beneficial for further improving the hardness and toughness of the cemented carbide.

[0013] In some embodiments of this application, the cemented carbide further includes an additive component, which comprises at least one carbide of Ta, Nb, and Cr; based on the total mass of the cemented carbide, the mass percentage of the additive component is ≤3%. This facilitates the pinning of hard phase grain boundaries, suppresses abnormal coarsening of hard phase grains during sintering, and further improves the hardness and wear resistance of the cemented carbide. Simultaneously, the high melting point and good high-temperature stability of the aforementioned additive component enhance the high-temperature strength of the cemented carbide.

[0014] In a second aspect, this application proposes a method for preparing a cemented carbide, comprising: S1. The raw material powder and molding agent are mixed to obtain the first mixture; The raw material powder includes hard phase powder, metal binder phase powder, and n-phase carbide powder. The difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the powder of the hard phase in the raw material powder is 0.17% to 0.35%. S2. Press the first mixture into a compact to obtain a cemented carbide blank; S3. The cemented carbide blank is sintered to obtain the cemented carbide, wherein the sintering process includes: Under vacuum conditions, the temperature is raised to 1350℃~1375℃ for the first sintering. Under an inert atmosphere pressure of 40 mbar to 60 mbar, the temperature is increased to 1400°C to 1450°C at a rate of 1°C / min to 3°C / min for the second sintering. The cemented carbide is obtained by cooling it to room temperature at a rate of 20°C / min to 50°C / min under a pressure of 50 bar to 70 bar.

[0015] This application achieves a synergistic effect by introducing η-phase carbide powder into the raw material powder, controlling the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder, and using a specific sintering process. These three factors work together to construct a nanoscale η-phase interface dispersion-strengthened structure in the cemented carbide, thereby achieving a synergistic improvement in the hardness and toughness of the cemented carbide.

[0016] In some embodiments of this application, the method for preparing the cemented carbide satisfies at least one of the following conditions: (1) The average grain size of the η-phase carbide powder is 0.1 μm to 0.3 μm; (2) The average grain size of the hard phase powder is 0.6 μm to 5 μm; (3) Based on the total mass of the raw material powder, the mass percentage of the carbide powder of the η phase is 2% to 10%.

[0017] This is beneficial for further improving the strength and toughness of cemented carbide.

[0018] The third aspect of this application provides the application of the cemented carbide provided in the first aspect of this application or the cemented carbide prepared by the method provided in the second aspect of this application in cutting tools, mining tools, or wear-resistant parts. Because the cemented carbide provided in the first aspect of this application or the cemented carbide prepared by the method provided in the second aspect of this application possesses both good hardness and toughness, the cemented carbide of this application is suitable for manufacturing cutting tools, mining tools, and various wear-resistant parts with stringent strength and toughness requirements, and can significantly improve the service life and reliability of tools.

[0019] This application has at least the following beneficial effects: (1) This application proposes a cemented carbide in which the η phase particles are nanoscale in size and at least 70% of the η phase particles are dispersed in the interface region between the hard phase and the metal binder phase. On the one hand, the nano η phase itself has high hardness, and its dispersed distribution effectively hinders dislocation movement, thereby suppressing the crack propagation of the cemented carbide, making the hardness HV30 of the cemented carbide ≥1486; on the other hand, the η phase is nanoscale, which reduces the severe interruption of the continuity of the metal binder phase. At the same time, its dispersed distribution in the interface region between the hard phase and the metal binder phase can effectively pin grain boundaries and suppress the abnormal growth of hard phase particles, and can also enhance the metal binder phase through the nano-dispersion strengthening mechanism, making the fracture toughness of the cemented carbide ≥14.2MPa·m. 1 / 2 Thus, the cemented carbide provided in this application achieves an excellent balance between hardness and toughness.

[0020] (2) This application proposes a method for preparing cemented carbide. By introducing η-phase carbide powder into the raw material powder, controlling the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder, and combining a specific sintering process, the three factors work synergistically to construct a nanoscale η-phase interface dispersion-strengthened structure in the cemented carbide, thereby achieving a synergistic improvement in the hardness and toughness of the cemented carbide. The cemented carbide prepared by the method provided in this application has a stable microstructure and strong process controllability. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is an optical metallographic microscope image of the cemented carbide of Embodiment 1 of this application at a magnification of 150x. Figure 2 This is a schematic diagram of the cemented carbide used in this application.

[0022] Figure labeling: Hard phase: 1; Metal bonded phase: 2; η phase: 3. Detailed Implementation

[0023] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0024] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0025] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0026] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0027] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] In the description of this application, 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 technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.

[0029] In the description of this application, "multiple" means two or more.

[0030] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0032] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0033] In a first aspect of this application, a cemented carbide is provided, comprising a hard phase, a metallic binder phase, and an η phase; The η phase is a carbide, and the equivalent particle size of the η phase is 10 nm to 200 nm. Based on the total volume of the cemented carbide, the volume fraction of the η phase is 1% to 8%; Based on the total volume of the η phase, at least 70% of the η phase particles are distributed in a dispersed state at the interface region between the hard phase and the metal bonding phase.

[0034] In this application, the η-phase particles in the cemented carbide are nanoscale in size, and at least 70% of the η-phase particles are dispersed in the interface region between the hard phase and the metal binder phase. On the one hand, the nanoscale η-phase itself has high hardness, and its dispersed distribution effectively hinders dislocation movement, thereby suppressing crack propagation in the cemented carbide, resulting in a hardness HV30 ≥ 1486. ​​On the other hand, the nanoscale size of the η-phase reduces severe disruption to the continuity of the metal binder phase. Simultaneously, its dispersed distribution in the interface region between the hard phase and the metal binder phase effectively pins grain boundaries, inhibits abnormal growth of hard phase particles, and strengthens the metal binder phase through a nano-dispersion strengthening mechanism, resulting in a fracture toughness of ≥ 14.2 MPa·m in the cemented carbide. 1 / 2 Thus, the cemented carbide provided in this application achieves an excellent balance between hardness and toughness.

[0035] As an example, the equivalent particle size of the η phase can be 10nm, 20nm, 30nm, 38nm, 40nm, 50nm, 60nm, 70nm, 72nm, 80nm, 90nm, 100nm, 120nm, 150nm, 180nm, 200nm, or a range of any two of these values.

[0036] As an example, based on the total volume of the cemented carbide, the volume fraction of the η phase can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or a range of any two of these values.

[0037] As an example, based on the total volume of the η phase, the volume percentage of η phase particles dispersed in the interface region between the hard phase and the metal binder phase can be 70%, 75%, 80%, 85%, 90%, 95%, 100%, or any two of these values.

[0038] In this application, "equivalent particle size of η phase" refers to the volume average particle size of η phase particles, which is obtained by observing the microstructure of cemented carbide using an optical metallographic microscope (LOM) and measuring 100 η phase particles using image analysis software.

[0039] Figure 1 This is an optical metallurgical microscope image of one embodiment of this application. The black particles represent the n-phase. Figure 1 It can be seen that the η phase particles are dispersed in the interface region between the hard phase and the metal binder phase.

[0040] In this application, "the interface region between the hard phase and the metal binder phase" refers to the phase interface and adjacent region between the hard phase particles and the metal binder phase, a region with a thickness of 0.05 μm to 5 μm extending towards the metal binder phase side with the surface of the hard phase particles as a reference.

[0041] Figure 2 This is a schematic diagram of the cemented carbide of this application, in which the black particles are the η phase, which is uniformly dispersed in the interface region between the cemented phase and the metal binder phase.

[0042] In this application, the volume fraction of η-phase particles in cemented carbide and the proportion of η-phase particles dispersed in the phase interface region are determined by the following methods: Metallographic samples were prepared by polishing and etching the samples. The microstructure was observed by scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS) to identify the η phase, hard phase, metal binder phase and interface region; Ten fields of view were selected, and image analysis software was used to identify and count the η-phase particles. Under random cross-sectional conditions, the area fraction of the two-dimensional cross-section is approximated to the volume fraction of the three-dimensional cross-section. The proportion of the η phase area to the total area is statistically analyzed, and the average value is taken as the volume fraction of the η phase in the cemented carbide.

[0043] In this application, the proportion of η-phase particles in a dispersed state at the phase interface region between the hard phase and the metallic binder phase was determined using the following method: The samples were observed using the backscattered electron (BSE) mode of a field emission scanning electron microscope. More than 20 fields of view were randomly selected across the sample cross-section for image acquisition.

[0044] Image analysis software was used to perform threshold segmentation on BSE images, and EDS component analysis was combined to determine the η-phase region. The equivalent circle diameter (ECD) of the η-connected regions was used as the evaluation index. When ECD ≤ 1 μm, it was defined as a dispersed η-phase, and when ECD > 1 μm, it was defined as an aggregated η-phase.

[0045] The dispersion rate of phase η, which is the proportion of phase η distributed in a diffuse state in the phase interface region, is calculated according to the following formula: D = Ad / At × 100% Where D is the dispersion rate of the η phase, Ad is the total area of ​​the dispersed η phase, and At is the total area of ​​all η phases. The D value is used as the volume percentage of η phase particles that are dispersed in the interface region between the hard phase and the metallic binder phase.

[0046] In some embodiments of this application, the hard phase includes WC. This is advantageous for further improving the hardness of the cemented carbide.

[0047] In some embodiments of this application, the metallic binder phase includes at least one of Co and Ni. This is advantageous for further improving the toughness and hardness of the cemented carbide.

[0048] In some embodiments of this application, the η phase includes M6C, M 12 At least one of C-type carbides; wherein the M element includes at least one of W, Co, and Ni. Therefore, the above-mentioned M6C, M... 12 C-type carbides possess a dense crystalline structure and high intrinsic hardness, allowing them to be finely dispersed in the microstructure of cemented carbides. They achieve grain refinement and dispersion strengthening by pinning grain boundaries and hindering dislocation movement. At the same time, they exhibit good thermodynamic stability and strong microstructure adaptability, making it easy to control the carbon balance and microstructure of the alloy. This improves the hardness, wear resistance, and high-temperature stability of the alloy while reducing the continuous precipitation of brittle phases, thus giving cemented carbides good strength and toughness.

[0049] As an example, the η phase can be Co. 12 W 12 C, Co6W6C, etc.

[0050] In some embodiments of this application, the shape of the η-phase particles includes quasi-spherical and / or ellipsoidal shapes. In this application, quasi-spherical refers to a particle shape that is close to a sphere and has no sharp edges; ellipsoidal refers to an ellipsoidal particle shape with an aspect ratio of 1 to 3. The quasi-spherical and / or ellipsoidal shape of the η-phase particles is beneficial for the uniform dispersion of the η-phase particles in the interface region, reducing stress concentration and improving the toughness of the cemented carbide.

[0051] In some embodiments of this application, the aspect ratio of the η-phase particles is between 1 and 2. For example, the aspect ratio of the η-phase particles can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, or a range of any two values ​​therein. An aspect ratio of 1 to 2 for the η-phase particles indicates that the particles are quasi-spherical or nearly ellipsoidal, with good dispersion, which is beneficial for improving the hardness and toughness of cemented carbide.

[0052] In this application, the aspect ratio of the η-phase particles refers to the ratio of the longest axis dimension to the shortest axis dimension of the η-phase particles. The longest axis dimension is the maximum straight-line distance of the particle in the plane projection, and the shortest axis dimension is the minimum straight-line distance of the particle perpendicular to the longest axis direction. The aspect ratio was measured by observing and counting 100 η-phase particles using a scanning electron microscope (SEM).

[0053] In some embodiments of this application, the coercivity of the cemented carbide is 100 Oe to 250 Oe. For example, the coercivity of the cemented carbide can be 100 Oe, 115 Oe, 130 Oe, 145 Oe, 160 Oe, 175 Oe, 190 Oe, 205 Oe, 220 Oe, 235 Oe, 250 Oe, or a range consisting of any two of these values. Having the coercivity of the cemented carbide within the above range is beneficial for the cemented carbide to possess both high hardness, good toughness, and structural stability.

[0054] In this application, the coercivity was measured in accordance with GB / T3848-2017 "Method for Determination of Coercivity (Magnetic) Force of Hard Alloy", that is, by using the DC magnetic saturation-demagnetization method.

[0055] In some embodiments of this application, the average grain size of the hard phase particles is 0.6 μm to 2 μm. For example, the average grain size of the hard phase particles can be 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, or a range consisting of any two of these values. An average grain size of the hard phase particles within the above range is beneficial for further improving the hardness and toughness of the cemented carbide.

[0056] In this application, the average grain size of the hard phase particles is determined according to GB / T3488.2-2025 using the scribing method: the microstructure is observed by metallographic microscope, 5 fields of view are randomly selected, and lines are randomly cribing in multiple directions within the fields of view for a total of 10 times. The number of hard phase particles intercepted by the cribing is counted, and the average grain size is calculated as: average grain size = total length of all cribing lines / total number of grains cut by the lines.

[0057] In some embodiments of this application, the equivalent particle size of the η phase is 10 nm to 100 nm; preferably, the equivalent particle size of the η phase is 38 nm to 72 nm. This is beneficial for further improving the hardness and toughness of the cemented carbide.

[0058] In some embodiments of this application, the mass percentage of the metal binder phase is 8% to 15% based on the total mass of the cemented carbide. For example, the mass percentage of the metal binder phase can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or a range consisting of any two of these values. When the mass percentage of the metal binder phase is within the above range, it can fully encapsulate the hard phase particles, which is beneficial for the densification of the cemented carbide and further improves its strength, toughness, and impact resistance.

[0059] In some embodiments of this application, the mass percentage of the η phase is 2% to 10% based on the total mass of the cemented carbide. For example, the mass percentage of the η phase can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range consisting of any two of these values. With the mass percentage of the η phase within the above range, an appropriate amount of η phase is dispersed in the interface region between the hard phase and the metal binder phase, which can play a role in second-phase strengthening and microstructure refinement, significantly improving the hardness of the cemented carbide. Simultaneously, the η phase within the above range can pin the grain boundaries of the hard phase, suppressing abnormal coarsening of the hard phase grains during sintering, making the grain size of the hard phase uniform and controllable, and resulting in good microstructural stability. Furthermore, it also helps to suppress the formation of a continuous brittle network of the η phase. Therefore, the hardness and toughness of the cemented carbide are further improved.

[0060] In some embodiments of this application, the cemented carbide further includes an additive component, which comprises at least one carbide of Ta, Nb, and Cr; based on the total mass of the cemented carbide, the mass percentage content of the additive component is ≤3%. For example, the mass percentage content of the additive component can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or a range of any two of these values. The inclusion of the above-mentioned additive component in the cemented carbide facilitates the pinning of hard phase grain boundaries, suppresses abnormal coarsening of hard phase grains during sintering, and further improves the hardness and wear resistance of the cemented carbide. Simultaneously, the high melting point and good high-temperature stability of the above-mentioned additive component can enhance the high-temperature strength of the cemented carbide.

[0061] As an example, the additive components include at least one of TaC, NbC, and Cr3C2.

[0062] In some embodiments of this application, the mass percentage of the hard phase is 72% to 90% based on the total mass of the cemented carbide. For example, the mass percentage of the hard phase can be 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, or a range of any two of these values. This is beneficial for further improving the hardness and toughness of the cemented carbide.

[0063] In a second aspect, this application proposes a method for preparing cemented carbide. This method involves introducing η-phase carbide powder into the raw material powder, controlling the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder, and employing a specific sintering process. These three factors work synergistically to construct a nanoscale η-phase interfacial dispersion-strengthened structure in the cemented carbide, thereby achieving a synergistic improvement in the hardness and toughness of the cemented carbide. The cemented carbide prepared by the method provided in this application exhibits a stable microstructure and strong process controllability. Specifically, by introducing η-phase carbide powder into the raw material powder, it is beneficial to achieve precise control over the size of the nanoscale η-phase. Simultaneously, by controlling the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the cemented carbide powder in the raw material powder to be 0.17%-0.35%, a stable carbon potential is provided for maintaining the nanoscale η-phase. Furthermore, by combining a two-stage process of low-temperature vacuum sintering (first sintering) and high-temperature pressure sintering (second sintering), and by controlling the heating rate of the second sintering, the nucleation and growth kinetics of the η-phase are precisely controlled, allowing it to disperse at the interface at a nanoscale size. Finally, rapid cooling under pressure freezes the target microstructure, inhibiting its coarsening. Specifically, this method includes: S1. The raw material powder and molding agent are mixed to obtain the first mixture.

[0064] This application does not impose any particular restrictions on molding agents, as long as they can achieve the purpose of this application. For example, molding agents may include at least one of paraffin wax and polyethylene glycol (PEG).

[0065] This application does not have any particular limitation on the above mixing process, as long as it can achieve the purpose of this application. For example, the raw material powder and the molding agent are ball-milled and dispersed for 30h~90h, and then spray-granulated to obtain the first mixture.

[0066] In some embodiments of this application, the raw material powder includes powder of a hard phase, powder of a metal binder phase, and n-phase carbide powder.

[0067] In some embodiments of this application, the average grain size of the η-phase carbide powder is 0.1 μm to 0.3 μm. For example, the average grain size of the η-phase carbide powder can be 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, or a range consisting of any two of these values. By controlling the average grain size of the η-phase carbide powder within the above range, it is beneficial to stably form a nanoscale η-phase after the raw material powder is sintered. This facilitates its uniform dispersion in the interface region between the hard phase and the metal binder phase, achieving grain boundary pinning and dislocation hindering strengthening, thereby further improving the strength and toughness of the cemented carbide.

[0068] In some embodiments of this application, the η-phase carbide powder includes M6C, M... 12 At least one of C-type carbides; wherein the M element includes at least one of W, Co, and Ni. For example, η-phase carbide powder may include Co. 12 W 12 C, Co6W6C, etc.

[0069] This application does not impose any particular limitation on the preparation method of the η-phase carbide powder, as long as it achieves the purpose of this application. For example, the preparation method of the η-phase carbide powder can be: according to Co6W6C or Co... 12 W 12 Weigh out Co powder, W powder and carbon black according to the stoichiometric ratio of C, put the raw materials into a planetary ball mill for mixing, heat to 1000℃-1200℃ under N2 atmosphere protection, hold for 1h-2h, cool and then crush the powder by airflow to obtain η phase carbide powder with an average grain size of 0.1μm~0.3μm.

[0070] In some embodiments of this application, the average grain size of the hard phase powder is 0.6 μm to 5 μm. For example, the average grain size of the hard phase powder can be 0.6 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or a range consisting of any two of these values. By controlling the hard phase powder within the above range, abnormal grain coarsening of the hard phase during sintering can be suppressed, balancing the density, microstructure uniformity, and hardness and toughness of the cemented carbide, thereby further improving the strength and toughness of the cemented carbide.

[0071] In this application, the average grain size of the η-phase carbide powder and the hard phase powder is determined by the following method: the powder sample is dispersed in anhydrous ethanol by ultrasonic dispersion using a laser particle size analyzer, the particle size distribution is detected by the laser particle size analyzer, and the volume-weighted average particle size is calculated to obtain the average grain size of the powder.

[0072] In some embodiments of this application, the mass percentage of the η-phase carbide powder is 2% to 10% based on the total mass of the raw material powder. The mass percentage of the η-phase carbide powder can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range consisting of any two of these values. Having the mass percentage of the η-phase carbide powder within the above range is beneficial for improving the hardness and toughness of the cemented carbide.

[0073] In some embodiments of this application, the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.17%-0.35%; as an example, the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder can be 0.17%, 0.18%, 0.19%, 0.2%, 0.22%, 0.25%, 0.27%, 0.29%, 0.3%, 0.32%, 0.35wt%, or a range consisting of any two of these values.

[0074] In this application, "substoichiometric carbon content of cemented carbide" refers to the theoretical carbon content required when all the metallic elements in the raw material powder that form the hard phase in the cemented carbide are stoichiometrically converted into the hard phase. For example, if the hard phase of the cemented carbide is WC, then the theoretical carbon content required for all the WC powder and W powder in the raw material powder to be converted into WC (i.e., the molar ratio of W to C is 1:1) is calculated. For example, the substoichiometric carbon content of WC cemented carbide is calculated using the following formula: C 理论 =W 总 ×(M C / M WC ); where C 理论 W represents the substoichiometric carbon content of the cemented carbide. 总 M is the total mass fraction of WC powder and W powder in the raw material powder; C M is the relative atomic mass of carbon, with a value of 12.01; WC This represents the relative molecular mass of tungsten carbide, with a value of 195.85.

[0075] As an example, in the raw material powder for preparing WC cemented carbide, the mass percentage of WC powder in the raw material powder is Y, and the actual carbon content in the WC powder is N. Then, the "total mass fraction of carbon in the hard phase powder in the raw material powder" is Y×N.

[0076] The difference between the substoichiometric carbon content of cemented carbide and the total mass fraction of carbon in the hard phase powder of the raw material powder is 0.17%~0.35%. This means the total mass fraction of carbon in the hard phase powder is lower than the substoichiometric carbon content of the cemented carbide, indicating that the raw material powder system is generally carbon-deficient. This difference can be adjusted by controlling the mass percentages of WC powder and W powder in the raw material powder. Increasing the mass percentage of W powder will increase the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder. Alternatively, the difference can be increased by adjusting the actual carbon content in the WC powder raw material. Decreasing the actual carbon content in the WC powder raw material will also increase the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder. As an example, the actual carbon content of WC powder raw material is 6.06%, which differs from the theoretical carbon content of WC powder by 0.07%. In order to achieve the difference between the substoichiometric carbon content of cemented carbide and the total mass fraction of carbon in the raw material powder of the hard phase powder, it can be further controlled by adjusting the content of W powder in the raw material.

[0077] S2. Press the first mixture into a shape to obtain a cemented carbide blank.

[0078] This application does not impose any particular restrictions on the conditions for compression molding, as long as the purpose of this application can be achieved. For example, the applied pressure is 100MPa~200MPa.

[0079] S3. The cemented carbide is prepared by sintering the cemented carbide blank.

[0080] In some embodiments, the sintering process includes: Under vacuum conditions, the temperature is raised to 1350℃~1375℃ for the first sintering; under an inert atmosphere pressure of 40mbar~60mbar, the temperature is raised to 1400℃~1450℃ at a rate of 1℃ / min~3℃ / min for the second sintering; under a pressure of 50bar~70bar, the temperature is cooled to room temperature at a rate of 20℃ / min~50℃ / min to obtain the cemented carbide.

[0081] As an example, the temperature for the first sintering can be 1350℃, 1355℃, 1360℃, 1365℃, 1370℃, 1375℃, or a range of any two of these values.

[0082] As an example, the pressure during the second sintering can be 40 mbar, 44 mbar, 48 mbar, 50 mbar, 52 mbar, 56 mbar, 60 mbar, or a range of any two of these values.

[0083] As an example, the heating rate during the second sintering can be 1℃ / min, 1.2℃ / min, 1.5℃ / min, 1.8℃ / min, 2℃ / min, 2.2℃ / min, 2.5℃ / min, 2.8℃ / min, 3℃ / min, or a range of any two of these values.

[0084] As an example, the temperature for the second sintering can be 1400℃, 1410℃, 1420℃, 1430℃, 1440℃, 1450℃, or a range of any two of these values.

[0085] As an example, after the second calcination, the temperature cooling rate can be 20℃ / min, 25℃ / min, 30℃ / min, 35℃ / min, 40℃ / min, 45℃ / min, 50℃ / min, or a range of any two of these values.

[0086] As an example, after the second calcination, the cooling pressure can be 50 bar, 55 bar, 60 bar, 65 bar, 70 bar, or a range of any two of these values.

[0087] This application does not impose any particular limitation on the heating rate of the first sintering, as long as the purpose of this application can be achieved. For example, the heating rate of the first sintering can be 2℃ / min to 5℃ / min. This application does not impose any particular limitation on the holding time of the first sintering, as long as the purpose of this application can be achieved. For example, the holding time of the first sintering can be 10min to 20min.

[0088] This application does not impose any particular limitation on the holding time of the second sintering, as long as the purpose of this application can be achieved. For example, the holding time of the second sintering can be 20 min to 90 min.

[0089] In some embodiments of this application, step S3, prior to the first sintering, includes a vacuum removal of the forming agent: under vacuum conditions, the temperature is increased to 280°C to 300°C at a rate of 1°C / min to 1.2°C / min, and held for 50 to 70 minutes. This treatment helps to remove the forming agent from the cemented carbide blank, reducing problems such as residual carbon, porosity, and structural defects.

[0090] A third aspect of this application provides the application of the cemented carbide provided in the first aspect of this application or the cemented carbide prepared by the method provided in the second aspect of this application in cutting tools, mining tools, or wear-resistant parts. Because the cemented carbide provided in the first aspect of this application or the cemented carbide prepared by the method provided in the second aspect of this application possesses both good hardness and toughness, the cemented carbide of this application is suitable for manufacturing cutting tools, mining tools, and various wear-resistant parts with stringent strength and toughness requirements, significantly improving tool life and reliability.

[0091] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0092] The following specific embodiments illustrate the solution of this application. It should be noted that these 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 this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0093] Example 1 S0. Preparation of η-phase carbide powder: Weigh Co powder, W powder and industrial carbon black according to the stoichiometric ratio of Co6W6C; mix the above raw materials in a planetary ball mill; sinter at 1200℃ for 2 hours under N2 atmosphere protection; then crush the sintered powder by airflow to obtain η-phase carbide powder with an average grain size of 0.15μm.

[0094] S1. Weigh out WC powder (actual carbon content 6.06%) with an average grain size of 3.0 μm, Co powder, η-phase carbide powder (Co6W6C) with an average grain size of 0.15 μm prepared in S0, Cr3C2 powder, NbC powder, and W powder according to the mass percentage of each component in Table 1 to obtain raw material powder. Then, add paraffin and alcohol and ball mill and mix for 48 h. After ball milling and mixing, perform spray granulation treatment to obtain the first mixture. Among them, according to the above formula, the difference between the substoichiometric carbon content of cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.22%, that is, the carbon deficiency of the raw material powder is 0.22%. Specifically, according to the ingredients in Table 1, the substoichiometric carbon content of the cemented carbide is: (81.8% + 2.6%) × (12.01 / 195.85) = 5.18%; the total mass fraction of carbon in the WC powder in the raw material powder is: 81.8% × 6.06% = 4.96%, that is, the difference between the two is 0.22%.

[0095] Table 1

[0096] S2. Press the first mixture obtained in step S1 into a cemented carbide compact under a pressure of 200 MPa. S3. The above-mentioned cemented carbide blank is sintered, and the sintering process includes: Vacuum dewaxing stage: Under vacuum conditions, the temperature is increased to 290℃ at a rate of 1.1℃ / min and held for 60min; First sintering stage (low-temperature vacuum sintering): Under vacuum conditions, the temperature is increased to 1365℃ at a rate of 3℃ / min and held for 15min. The second sintering stage (high temperature and pressure sintering): Under a pressure of 50 mbar N2, the temperature is increased to 1420℃ at a rate of 2℃ / min and held for 45 min. Pressurized cooling stage: Under N2 pressure of 60 bar, the cemented carbide is cooled to room temperature at a rate of 30 °C / min to obtain cemented carbide.

[0097] Example 2 S0. Preparation of η-phase carbide powder: Weigh Co powder, W powder and industrial carbon black according to the stoichiometric ratio of Co6W6C; mix the above raw materials in a planetary ball mill; sinter at 1150℃ for 1.5h under N2 atmosphere protection; then crush the sintered powder by airflow to obtain η-phase carbide powder with an average grain size of 0.1μm.

[0098] S1. Weigh out the following powders according to the mass percentage of each component in Table 2: WC powder (actual carbon content 6.06%) with an average grain size of 1.0 μm, Co powder, Ni powder, η-phase carbide powder (Co6W6C) with an average grain size of 0.1 μm prepared from S0, Cr3C2 powder, NbC powder, and W powder. This yields the raw material powder. Paraffin wax and alcohol are then added, and the mixture is ball-milled for 52 hours. After ball milling, the mixture is spray-granulated to obtain the first mixture. According to the above formulation, the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.33%, meaning the carbon deficiency in the raw material powder is 0.33%.

[0099] Table 2

[0100] S2. Press the first mixture obtained in step S1 into a cemented carbide compact under a pressure of 150 MPa. S3. The above-mentioned cemented carbide blank is sintered, and the sintering process includes: Vacuum dewaxing stage: Under vacuum conditions, the temperature is increased to 300℃ at a rate of 1℃ / min and held for 50min; First vacuum sintering stage: Under vacuum conditions, the temperature is increased to 1370℃ at a rate of 4℃ / min and held for 12min; Second pressure sintering stage: Under N2 pressure of 45 mbar, the temperature is increased to 1430℃ at a rate of 2℃ / min and held for 55 min; Pressurized cooling stage: Under N2 pressure of 55 bar, the cemented carbide was cooled to room temperature at a rate of 20 °C / min to obtain cemented carbide.

[0101] Example 3 S0. Preparation of η-phase carbide powder: Weigh Co powder, W powder and industrial carbon black according to the stoichiometric ratio of Co6W6C; mix the above raw materials in a planetary ball mill; sinter at 1100℃ for 1 hour under N2 atmosphere protection; then crush the sintered powder by airflow to obtain η-phase carbide powder with an average grain size of 0.3μm.

[0102] S1. Weigh out WC powder (actual carbon content 6.06%) with an average grain size of 5.0 μm, Co powder, η-phase carbide powder (Co6W6C) with an average grain size of 0.3 μm prepared in S0, Cr3C2 powder, NbC powder, and W powder according to the mass percentage of each component in Table 3 to obtain raw material powder. Then add paraffin and alcohol and ball mill for 40 h. After ball milling, granulate to obtain the first mixture. According to the above formula, the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.19%, that is, the carbon deficiency of the raw material powder is 0.19%.

[0103] Table 3

[0104] S2. Press the first mixture obtained in step S1 into a cemented carbide blank under a pressure of 100 MPa. S3. The above-mentioned cemented carbide blank is sintered, and the sintering process includes: Vacuum dewaxing stage: Under vacuum conditions, the temperature is increased to 285℃ at a rate of 1.2℃ / min and held for 70min; First vacuum sintering stage: Under vacuum conditions, the temperature is increased to 1355℃ at a rate of 2.5℃ / min and held for 18min; Second pressure sintering stage: Under N2 pressure of 60 mbar, the temperature is increased to 1440℃ at a rate of 1.5℃ / min and held for 60 min; Pressurized cooling stage: Under N2 pressure of 70 bar, the cemented carbide was cooled to room temperature at a rate of 25 °C / min to obtain the cemented carbide.

[0105] Example 4 S0. Preparation of η-phase carbide powder: Weigh Co powder, W powder and industrial carbon black according to the stoichiometric ratio of Co6W6C; mix the above raw materials in a planetary ball mill; sinter at 1200℃ for 2 hours under N2 atmosphere protection; then crush the sintered powder by airflow to obtain η-phase carbide powder with an average grain size of 0.1μm.

[0106] S1. Weigh out WC powder (actual carbon content 6.06%) with an average grain size of 0.6 μm, Co powder, η-phase carbide powder (Co6W6C) with an average grain size of 0.1 μm prepared in S0, Cr3C2 powder, NbC powder, and W powder according to the mass percentage of each component in Table 4 to obtain raw material powder. Then add paraffin and alcohol and ball mill for 90 h. After ball milling, perform spray granulation to obtain the first mixture. According to the above formula, the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.26%, that is, the carbon deficiency of the raw material powder is 0.26%.

[0107] Table 4

[0108] S2. Press the first mixture obtained in step S1 into a cemented carbide compact under a pressure of 200 MPa. S3. The above-mentioned cemented carbide blank is sintered, and the sintering process includes: Vacuum dewaxing stage: Under vacuum conditions, the temperature is increased to 290℃ at a rate of 1.1℃ / min and held for 60min; First vacuum sintering stage: Under vacuum conditions, the temperature is increased to 1365℃ at a rate of 3℃ / min and held for 15min; Second pressure sintering stage: Under N2 pressure of 50 mbar, the temperature is increased to 1420℃ at a rate of 2℃ / min and held for 45min; Pressurized cooling stage: Under N2 pressure of 60 bar, the cemented carbide is cooled to room temperature at a rate of 30 °C / min to obtain cemented carbide.

[0109] Example 5 S0. Preparation of η-phase carbide powder: Weigh Co powder, W powder and industrial carbon black according to the stoichiometric ratio of Co6W6C; mix the above raw materials in a planetary ball mill; sinter at 1200℃ for 2 hours under N2 atmosphere protection; then crush the sintered powder by airflow to obtain η-phase carbide powder with an average grain size of 0.3μm.

[0110] S1. Weigh out WC powder (actual carbon content 6.06%) with an average grain size of 5.0 μm, Co powder, η-phase carbide powder (Co6W6C) with an average grain size of 0.3 μm prepared in S0, Cr3C2 powder, NbC powder, and W powder according to the mass percentage of each component in Table 5 to obtain raw material powder. Then add paraffin and alcohol and ball mill and mix for 30 h. After ball milling and mixing, perform spray granulation treatment to obtain the first mixture. Among them, according to the above formula, the difference between the substoichiometric carbon content of cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.21%, that is, the carbon deficiency of the raw material powder is 0.21%.

[0111] Table 5

[0112] S2. Press the first mixture obtained in step S1 into a cemented carbide compact under a pressure of 200 MPa. S3. The above-mentioned cemented carbide blank is sintered, and the sintering process includes: Vacuum dewaxing stage: Under vacuum conditions, the temperature is increased to 290℃ at a rate of 1.1℃ / min and held for 60min; First vacuum sintering stage: Under vacuum conditions, the temperature is increased to 1365℃ at a rate of 3℃ / min and held for 15min; Second pressure sintering stage: Under N2 pressure of 50 mbar, the temperature is increased to 1420℃ at a rate of 2℃ / min and held for 45min; Pressurized cooling stage: Under N2 pressure of 60 bar, the cemented carbide is cooled to room temperature at a rate of 30 °C / min to obtain cemented carbide.

[0113] Example 6 S0. Preparation of η-phase carbide powder: Weigh Co powder, W powder and industrial carbon black according to the stoichiometric ratio of Co6W6C; mix the above raw materials in a planetary ball mill; sinter at 1200℃ for 2 hours under N2 atmosphere protection; then crush the sintered powder by airflow to obtain η-phase carbide powder with an average grain size of 0.3μm.

[0114] S1. Weigh out WC powder (actual carbon content 6.06%) with an average grain size of 3.0 μm, Co powder, η-phase carbide powder (Co6W6C) with an average grain size of 0.3 μm prepared in S0, Cr3C2 powder, NbC powder, and W powder according to the mass percentage of each component in Table 6 to obtain raw material powder. Then add paraffin and alcohol and ball mill and mix for 48 h. After ball milling and mixing, perform spray granulation treatment to obtain the first mixture. Among them, according to the above formula, the difference between the substoichiometric carbon content of cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.2%, that is, the carbon deficiency of the raw material powder is 0.2%.

[0115] Table 6

[0116] S2. Press the first mixture obtained in step S1 into a cemented carbide compact under a pressure of 200 MPa. S3. The above-mentioned cemented carbide blank is sintered, and the sintering process includes: Vacuum dewaxing stage: Under vacuum conditions, the temperature is increased to 290℃ at a rate of 1.1℃ / min and held for 60min; First vacuum sintering stage: Under vacuum conditions, the temperature is increased to 1365℃ at a rate of 3℃ / min and held for 15min; Second pressure sintering stage: Under N2 pressure of 50 mbar, the temperature is increased to 1420℃ at a rate of 2℃ / min and held for 45min; Pressurized cooling stage: Under N2 pressure of 60 bar, the cemented carbide is cooled to room temperature at a rate of 30 °C / min to obtain cemented carbide.

[0117] Example 7 S0. Preparation of η-phase carbide powder: Weigh Co powder, W powder and industrial carbon black according to the stoichiometric ratio of Co6W6C; mix the above raw materials in a planetary ball mill; sinter at 1200℃ for 2 hours under N2 atmosphere protection; then crush the sintered powder by airflow to obtain η-phase carbide powder with an average grain size of 0.15μm.

[0118] S1. Weigh out WC powder (actual carbon content 6.06%) with an average grain size of 3.0 μm, Co powder, η-phase carbide powder (Co6W6C) with an average grain size of 0.15 μm prepared in S0, Cr3C2 powder, NbC powder, and W powder according to the mass percentage of each component in Table 7 to obtain raw material powder. Then, add paraffin and alcohol and ball mill and mix for 48 h. After ball milling and mixing, perform spray granulation treatment to obtain the first mixture. Among them, according to the above formula, the difference between the substoichiometric carbon content of cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.31%, that is, the carbon deficiency of the raw material powder is 0.31%.

[0119] Table 7

[0120] S2. Press the first mixture obtained in step S1 into a cemented carbide compact under a pressure of 200 MPa. S3. The above-mentioned cemented carbide blank is sintered, and the sintering process includes: Vacuum dewaxing stage: Under vacuum conditions, the temperature is increased to 290℃ at a rate of 1.1℃ / min and held for 60min; First vacuum sintering stage: Under vacuum conditions, the temperature is increased to 1365℃ at a rate of 3℃ / min and held for 15min; Second pressure sintering stage: Under N2 pressure of 50 mbar, the temperature is increased to 1420℃ at a rate of 2℃ / min and held for 45min; Pressurized cooling stage: Under N2 pressure of 60 bar, the cemented carbide is cooled to room temperature at a rate of 30 °C / min to obtain cemented carbide.

[0121] Example 8 Except for replacing the η-phase carbide powder in the raw material powder with η-phase carbide powder (Co6W6C) with an average grain size of 0.5 μm, the rest is the same as in Example 1.

[0122] Comparative Example 1 Except for not adding η-phase carbide powder to the raw material powder and adjusting the mass percentage of W powder so that the difference between the theoretical substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is kept at 0.22%, the rest is the same as in Example 1.

[0123] Comparative Example 2 Except for adjusting the mass percentage of W powder in the raw material powder so that the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.05%, the rest is the same as in Example 1.

[0124] Comparative Example 3 Except for adjusting the mass percentage of W powder in the raw material powder so that the difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the hard phase powder in the raw material powder is 0.4%, the rest is the same as in Example 1.

[0125] Comparative Example 4 Except for step S3, where the heating rate for the second sintering is adjusted to 5°C / min, the rest is the same as in Example 1.

[0126] Comparative Example 5 Except for step S3, where the cooling rate is adjusted to 10°C / min after the second sintering holding is completed, the rest is the same as in Example 1.

[0127] The microstructure and performance of the cemented carbides prepared in the above embodiments and comparative examples were characterized and tested, and the results are shown in Table 8.

[0128] Test of hardness HV30 of cemented carbide: Select a flat block sample, polish it, and use a Vickers hardness tester to perform an indentation test with a load of 30 kgf. The Vickers hardness value is calculated by measuring the length of the diagonal of the indentation and dividing the test force by the indentation area. For details, please refer to GB / T7997-2014 "Test Method for Vickers Hardness of Cemented Carbide".

[0129] Test of fracture toughness of cemented carbide: Select a flat block sample, polish it, use a Vickers hardness tester, select a load of 30 kgf for indentation test, measure the length of the indentation extension, and calculate the fracture toughness value by formula. For details, please refer to GB / T33819-2017 "Cemented Carbide Bacolod Toughness Test".

[0130] Table 8

[0131] Note: In Table 8, the volume fraction of the η phase in cemented carbide is represented as V1; the dispersion rate of the η phase is represented as D, which is the volume percentage of η phase particles that are dispersed in the interface region between the cemented phase and the metal binder phase; " / " indicates that the relevant substance or parameter does not exist.

[0132] As shown in Table 8, the equivalent particle size of the η phase in the cemented carbide prepared in Examples 1 to 8 of this application is 10 nm to 200 nm, the volume fraction of the η phase is 1% to 8%, the dispersion rate of the η phase is greater than 70%, and the hardness HV30 of the cemented carbide is ≥1486 and the fracture toughness is ≥14.2 MPa·m. 1 / 2This demonstrates that the cemented carbide provided in this application possesses both good hardness and fracture toughness. In contrast, the cemented carbide prepared in Comparative Example 1 has an equivalent particle size of the η phase that is outside the range of this application; the cemented carbide in Comparative Example 2 does not contain the η phase; the cemented carbide in Comparative Example 3 has a volume fraction of the η phase greater than 8%; the cemented carbides in Comparative Examples 4 and 5 have equivalent particle sizes of the η phase that are outside the range of this application; the dispersion rate of the η phase in the cemented carbides of Comparative Examples 1 to 5 is all less than 70%; the hardness HV30 of the cemented carbides of Comparative Examples 1 to 5 is all ≤1380; and the fracture toughness is all ≤13.8 MPa·m. 1 / 2 This indicates that the hardness and fracture toughness of the cemented carbide prepared in the comparative example are both poor.

[0133] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A cemented carbide, characterized in that, Includes hard phase, metallic binder phase and η phase; The η phase is a carbide, and the equivalent particle size of the η phase is 10 nm to 200 nm. Based on the total volume of the cemented carbide, the volume fraction of the η phase is 1% to 8%; Based on the total volume of the η phase, at least 70% of the η phase particles are distributed in a dispersed state at the interface region between the hard phase and the metal bonding phase.

2. The cemented carbide according to claim 1, characterized in that, The cemented carbide satisfies at least one of the following conditions: (1) The hard phase includes WC; (2) The metal binder phase includes at least one of Co and Ni.

3. The cemented carbide according to claim 1, characterized in that, The η phase includes M6C and M 12 At least one of the C-type carbides; wherein the M element includes at least one of W, Co, and Ni.

4. The cemented carbide according to any one of claims 1 to 3, characterized in that, The shape of the η-phase particles includes quasi-spherical and / or ellipsoidal, and / or the aspect ratio of the η-phase particles is 1 to 2.

5. The cemented carbide according to any one of claims 1 to 3, characterized in that, The cemented carbide satisfies at least one of the following conditions: (1) The coercivity of the hard alloy is 100 Oe to 250 Oe; (2) The average grain size of the hard phase particles is 0.6 μm to 2 μm; (3) The equivalent particle size of the η phase is 10nm~100nm.

6. The cemented carbide according to any one of claims 1 to 3, characterized in that, The equivalent particle size of the η phase is 38 nm to 72 nm.

7. The cemented carbide according to any one of claims 1 to 3, characterized in that, Based on the total mass of the cemented carbide, the mass percentage of the metal binder phase is 8% to 15%, and / or the mass percentage of the n phase is 2% to 10%.

8. The cemented carbide according to any one of claims 1 to 3, characterized in that, The cemented carbide further includes an additive component, which includes at least one of Ta, Nb, and Cr carbides; the mass percentage of the additive component is ≤3% based on the total mass of the cemented carbide.

9. A method for preparing a cemented carbide as described in any one of claims 1 to 8, characterized in that, include: S1. The raw material powder and molding agent are mixed to obtain the first mixture; The raw material powder includes hard phase powder, metal binder phase powder, and n-phase carbide powder. The difference between the substoichiometric carbon content of the cemented carbide and the total mass fraction of carbon in the powder of the hard phase in the raw material powder is 0.17% to 0.35%. S2. Press the first mixture into a compact to obtain a cemented carbide blank; S3. The cemented carbide blank is sintered to obtain the cemented carbide, wherein the sintering process includes: Under vacuum conditions, the temperature is raised to 1350℃~1375℃ for the first sintering. Under an inert atmosphere pressure of 40 mbar to 60 mbar, the temperature is increased to 1400°C to 1450°C at a rate of 1°C / min to 3°C / min for the second sintering. The cemented carbide is obtained by cooling it to room temperature at a rate of 20°C / min to 50°C / min under a pressure of 50 bar to 70 bar.

10. The method according to claim 9, characterized in that, At least one of the following conditions must be met: (1) The average grain size of the η-phase carbide powder is 0.1 μm to 0.3 μm; (2) The average grain size of the hard phase powder is 0.6 μm to 5 μm; (3) Based on the total mass of the raw material powder, the mass percentage of the carbide powder of the η phase is 2% to 10%.

11. The use of the cemented carbide according to any one of claims 1 to 8 or the cemented carbide prepared by the method according to any one of claims 9 to 10 in cutting tools, mining tools or wear-resistant parts.

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