High-entropy metal ceramic tool material for hard steel machining and preparation method thereof

Abstract

The application provides a high-entropy metal ceramic cutter material for hardening steel processing and a preparation method thereof, and belongs to the technical field of metal ceramic cutters.The cutter material is composed of a metal ceramic phase of Ti, Ta, W, Nb, Zr and other elements, and a binder phase of Co and Ni;after Zr is added, the toughness of the cutter is significantly improved;by adjusting the proportion of each component, the composition of the high-entropy ceramic phase and the C / N ratio are balanced to balance various performances.The cutter material is sintered at 1490-1530 DEG C and under a pressure of 1.5-2.5 kPa in an argon atmosphere.The application solves the problems of insufficient toughness and high-temperature resistance of existing cutters by special proportioning design of raw materials, components and process formulations, and has the advantages of low cost, long service life and optimized processing performance.

Description

Technical Field

[0001] This invention belongs to the field of metal-ceramic cutting tool technology, and particularly relates to a high-entropy metal-ceramic cutting tool material for machining hardened steel and its preparation method. Background Technology

[0002] Turning instead of grinding technology refers to the use of superhard cutting tools to precisely turn high-hardness materials, directly achieving grinding-grade dimensional accuracy and surface finish, thus eliminating the need for subsequent grinding processes. With the rapid development of polycrystalline cubic boron nitride (PCBN) cutting tools, ceramic cutting tools, and coating technologies, turning instead of grinding has been applied to some extent in the machining of workpieces such as hardened steel and chilled cast iron, achieving dimensional tolerances of IT5 to IT6 and surface roughness of Ra 0.2–0.4 μm under stable operating conditions. For machining objects with high wear resistance and high hardness, the cutting tools must possess excellent wear resistance, sufficient high-temperature resistance, and maintain high red hardness in the high-temperature cutting zone. Currently, some superhard cutting tools on the market can already meet these requirements for machining conventional hardened materials, giving turning instead of grinding significant advantages in terms of efficiency, flexibility, and green manufacturing.

[0003] In many current machining applications, both the workpiece substrate must possess high wear resistance, and the cutting tool must withstand extreme thermo-mechanical coupling during continuous cutting. Current tool materials still cannot meet the demands for long-life, high-precision, and stable machining. Therefore, when dealing with high-performance parts requiring even higher hardness, extremely high wear resistance, and stringent machining accuracy, existing turning-instead-of-grinding technologies still face significant challenges. Summary of the Invention

[0004] In order to develop a tool material that can replace polycrystalline cubic boron nitride (PCBN) tools, reduce the production cost of cutting tools in existing technologies for machining hardened steel, solve a series of problems that ordinary cermets cannot meet the comprehensive performance requirements of hardened steel tools, extend tool life, and improve the comprehensive performance of the workpiece, this invention proposes a high-entropy cermet tool material for machining hardened steel and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a high-entropy cermet tool material for machining hardened steel. The machining conditions suitable for the tool material of this invention include hard cutting, including turning instead of grinding. The suitable workpieces include hardened steel and other high-hardness, difficult-to-machine materials. The tool material comprises a high-entropy ceramic phase, a binder phase, and an auxiliary sintering phase. The high-entropy ceramic phase has the general formula (Ti) a ,Ta b W c ,Nb d ,Zr e(C) x N y ), where a, b, c, d, and e are the atomic fractions of Ti, Ta, W, Nb, and Zr, respectively, satisfying a+b+c+d+e=1, and a, b, c, d, and e are all greater than 0; x and y are the atomic fractions of C and N, respectively, satisfying x+y=1; The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1 to 2:1; The auxiliary sintering phase is Mo2C and Cr3C2, and the mass fraction ratio of Mo2C to Cr3C2 is 2 to 4:1. By mass fraction, the binder phase content in the tool material is 12% to 19%, the auxiliary sintering phase content is 2% to 5%, and the balance is a high-entropy ceramic phase.

[0006] The present invention also provides a method for preparing the above-mentioned high-entropy cermet cutting tool material for machining hardened steel, comprising the following steps: (1) Weigh each raw material powder according to the set component ratio, wherein the raw material powder includes TiN, TaC, NbC, ZrC, Mo2C, Cr3C2, WC, Co and carbonyl Ni powder; (2) Using alcohol as the wet grinding medium, polypropylene glycol and polyethyleneamine are added as forming agent and dispersant, respectively, and wet grinding is carried out to obtain a mixture; (3) After the mixture is spray-dried, granulated and molded, it is placed in a pressure sintering furnace with rapid cooling function for degreasing treatment; (4) After degreasing, vacuum sintering and heat preservation are carried out; (5) After the heat preservation is completed, the material is rapidly cooled and then removed from the furnace to obtain the high-entropy metal ceramic tool material for processing hardened steel.

[0007] Furthermore, in the raw material powder, the Fisher particle size of TiN, TaC, NbC, ZrC, Mo2C, Cr3C2 and Co powders is not greater than 1.5 μm, the Fisher particle size of carbonyl Ni powder is not greater than 2.5 μm, and the average particle size of WC powder with specific surface area is not greater than 0.3 μm.

[0008] Furthermore, the amount of polypropylene glycol added is 2.0% to 2.3% of the total mass of the raw material powder, and the amount of polyethyleneamine added is 0.05% to 0.10% of the total mass of the raw material powder.

[0009] Furthermore, the polypropylene glycol is PPG 4000, and the polyethyleneamine is PVAm 50000.

[0010] Furthermore, the vacuum sintering includes: holding at a sintering temperature of 1490℃~1530℃ for 20~30 minutes, then introducing inert gas to increase the pressure inside the furnace to 1.5kPa~2.5kPa, and continuing to hold at that temperature for 60~80 minutes.

[0011] Furthermore, prior to vacuum sintering, the process includes raising the furnace temperature to 1200℃~1350℃, introducing inert gas to bring the furnace pressure to 50Pa, and continuing to raise the temperature to a sintering temperature of 1490℃~1530℃. The inert gas is nitrogen and argon in a volume ratio of 2:1.

[0012] Furthermore, the rapid cooling involves cooling the furnace temperature to 1200°C within 1 hour, followed by further cooling to below 70°C before exiting the furnace.

[0013] Furthermore, the ball-to-material mass ratio in the wet milling is (4:1) to (5:1), and the wet milling time is 60 to 72 hours.

[0014] The principle of this invention is as follows: In the high-entropy cermet cutting tool material of this invention, the high-entropy hard phase (Ti,Ta,W,Nb,Zr)(C,N) introduces severe lattice distortion due to the differences in the atomic sizes of its multiple principal elements, strongly hindering dislocation slip and resulting in an intrinsic hardness far exceeding that of traditional single carbides. During sintering, the Co-Ni composite binder phase, through its interfacial compatibility with the high-entropy hard phase, enables the material to exhibit good fracture toughness while maintaining high hardness. When machining hardened steel, its high hardness and high toughness significantly prevent micro-chipping of the cutting edge and extend tool life.

[0015] During sintering, the Co-Ni composite binder phase effectively suppresses abnormal growth of hard phase grains through the dissolution-reprecipitation mechanism by rationally controlling the Co / Ni ratio. Combined with precise control of nitrogen / argon partial pressure for carbon-nitrogen balance in the segmented atmosphere sintering process, and the reduction of high-temperature dwell time through rapid cooling, this collectively promotes a fine and uniform microstructure. This is beneficial for sintering densification, improving the overall uniformity and reliability of the material. Atomic diffusion and dislocation recovery induced by frictional heat are significantly delayed, the Co-Ni binder phase is less prone to softening at high temperatures, and the high-entropy hard phase maintains structural stability.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects: The high-entropy cermet cutting tool material of this invention significantly improves hardness and red hardness compared to traditional cermet cutting tools. Traditional Co / Ni binder phases are inherently limited in hardness and easily soften at high temperatures, resulting in a rapid decrease in hardness, making them unsuitable for the near-thousand-degree Celsius temperatures at the tool tip during continuous high-speed cutting of hardened steel. In contrast, the high-entropy hard phase in this invention exhibits slow atomic diffusion at high temperatures, and the segmented atmosphere sintering process further optimizes the high-temperature stability of the hard phase through reasonable control of the C / N ratio, thus demonstrating excellent high-temperature resistance.

[0017] Compared to polycrystalline cubic boron nitride (PCBN) tools, the cutting tools of this invention have higher fracture toughness and anti-breakage ability. This is due to the synergistic toughening effect between the Co-Ni composite binder phase and the high-entropy hard phase, as well as the role of polypropylene glycol PPG 4000 and polyethyleneamine PVAm 50000 as forming agents and dispersants in the wet grinding process to ensure the uniformity of the mixture, thereby optimizing the cutting effect and service life of the tool.

[0018] The high-entropy hard phase used in this invention has a very low chemical affinity for ferrous metals, making it less likely to react with steel. Furthermore, the high-entropy hard phase diffuses slowly at high temperatures, thus exhibiting excellent high-temperature resistance. The tool material of this invention can be produced using conventional powder metallurgy processes (ball milling, die forming, pressure sintering), offering strong equipment compatibility, simplifying the production process, and reducing production costs. Simultaneously, the rapid cooling function reduces the furnace temperature from the sintering temperature to 1200℃ within one hour, effectively suppressing grain coarsening and ensuring the stability and consistency of material properties. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the cutting blade structure prepared by compression molding process in Example 1. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] The mainstream technical approach for existing high-entropy cermet cutting tools is to use high-entropy alloys as the binder phase (such as FeCoNiCrMn, AlCoCrFeNi, etc.). This invention, however, creatively employs a traditional Co-Ni composite binder phase combined with a high-entropy carbonitride hard phase, which is the most fundamental difference from existing technologies. Existing technologies generally believe that high-entropy alloys should be used as the binder phase to achieve performance breakthroughs. This invention, on the contrary, uses a traditional Co-Ni binder phase combined with a high-entropy hard phase. The core logic of this design is that the high-entropy hard phase itself already possesses lattice distortion strengthening and high-temperature stability, eliminating the need for a high-entropy alloy binder phase; furthermore, the traditional Co-Ni binder phase and the high-entropy hard phase have better interfacial wettability and thermal expansion matching, and precise control of the Co / Ni ratio can further optimize the interfacial bonding state. Specifically: This invention provides a high-entropy cermet tool material for machining hardened steel. The tool material is suitable for machining conditions including hard cutting such as turning instead of grinding. The suitable workpieces include hardened steel and other high-hardness, difficult-to-machine materials. The tool material contains a high-entropy ceramic phase, a binder phase, and an auxiliary sintering phase. High-entropy ceramic phases have the general formula (Ti a ,Ta b W c ,Nb d ,Zr e (C) x N y ), where a, b, c, d, and e are the atomic fractions of Ti, Ta, W, Nb, and Zr, respectively, satisfying a+b+c+d+e=1, and a, b, c, d, and e are all greater than 0; x and y are the atomic fractions of C and N, respectively, satisfying x+y=1; The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1–2:1. (Although Co and Ni are both iron group elements, Co has better wettability with high-entropy carbonitride hard phases than Ni, while Ni has better toughness than Co. A Co / Ni ratio of 1–2 ensures good wettability while also taking into account the toughness of the binder phase itself, achieving an optimal balance between interfacial bonding strength and overall toughness. Deviating from this ratio will lead to weakened interfacial bonding and a sharp decrease in fracture toughness.) The auxiliary sintering phases are Mo2C and Cr3C2, and the mass fraction ratio of Mo2C to Cr3C2 is 2 to 4:1. By mass fraction, the binder phase content in the tool material is 12%–19%, the auxiliary sintering phase content is 2%–5%, and the balance is a high-entropy ceramic phase.

[0026] This invention also provides a method for preparing the above-mentioned high-entropy cermet tool material for machining hardened steel, comprising the following steps: (1) Weigh each raw material powder according to the set component ratio. The raw material powder includes TiN, TaC, NbC, ZrC, Mo2C, Cr3C2, WC, Co and carbonyl Ni powder; (2) Using alcohol as the wet grinding medium, polypropylene glycol and polyethyleneamine are added as forming agent and dispersant, respectively, and wet grinding is carried out to obtain a mixture; (3) After the mixture is spray-dried, granulated and molded, it is placed in a pressure sintering furnace with rapid cooling function for degreasing treatment; (4) After degreasing, vacuum sintering and heat preservation are carried out; (5) After the heat preservation is completed, the material is rapidly cooled and then removed from the furnace to obtain high-entropy metal ceramic cutting tool material for hardened steel machining.

[0027] More specifically, the preparation method of high-entropy cermet tool material for machining hardened steel in this embodiment of the invention includes the following steps: (1) Weigh each raw material powder according to the set component ratio. The raw material powder includes TiN, TaC, NbC, ZrC, Mo2C, Cr3C2, WC, Co and carbonyl Ni powder. The Fisher particle size of TiN, TaC, NbC, ZrC, Mo2C, Cr3C2 and Co powders is not greater than 1.5μm, the Fisher particle size of carbonyl Ni powder is not greater than 2.5μm, and the average particle size of WC powder is not greater than 0.3μm (the nitrogen content of TiN must reach its theoretical nitrogen content, and the selection criteria for various carbides are that they must all meet the saturated carbon control requirements, that is, the total carbon content must all reach its theoretical carbon content). (2) Using alcohol as the wet grinding medium, PPG 4000 (2.0% to 2.3% of the total mass of the raw material powder) and PVAm 50000 (0.05% to 0.10% of the total mass of the raw material powder) were added as forming agent and dispersant, respectively, and wet grinding was carried out to obtain a mixture. The wet grinding was carried out using cemented carbide grinding balls with a ball-to-material mass ratio of (4:1) to (5:1) and a wet grinding time of 60 to 72 hours. (3) The mixture is spray-dried and granulated (120-150℃ in the granulation tower, 32-38s residence time for spraying wet material, and control the flowability to 45-55 s / 50g). Then, the cutting blade is prepared by molding process (stroke ratio 44-50, pressing force 39.2-49N). Then, it is placed in a pressure sintering furnace with rapid cooling function for degreasing treatment (800℃ for 2H) to remove the forming agent and dispersant. (4) After degreasing, raise the furnace temperature to 1200℃~1350℃, and introduce high-purity nitrogen and high-purity argon in a 2:1 ratio to make the pressure inside the sintering furnace reach 50Pa. This pressure is maintained until the temperature inside the sintering furnace reaches the sintering temperature of 1490~1530℃. Then, hold the furnace at the sintering temperature of 1490℃~1530℃ for 20~30 minutes, and then introduce high-purity argon to raise the pressure inside the furnace to 1.5kPa~2.5kPa, and continue to hold the furnace at the temperature for 60~80 minutes. (5) After the heat preservation is completed, the rapid cooling function of the sintering furnace is called to cool the furnace temperature to 1200°C within 1 hour, and then the furnace is cooled to a furnace exit temperature of less than 70°C to obtain high entropy metal ceramic tool material for hardened steel processing.

[0028] All raw materials used in the embodiments of the present invention were purchased commercially, and the purity of the high-purity nitrogen and high-purity argon used was ≥99.9%.

[0029] The technical solution of the present invention will be further illustrated by the following embodiments.

[0030] Example 1 In this embodiment, the binder phase content of the tool material is 14% by mass fraction, the auxiliary sintering phase content is 4.5%, and the balance is a high-entropy ceramic phase with an alloy composition of 81.5 wt.% (Ti). 0.3 Ta 0.2 W 0.25 Nb 0.15 Zr 0.1 (C) 0.7 N 0.3 )-9wt.%Co-5wt.%Ni-3.5wt.%Mo2C-1.0wt.%Cr3C2, that is: The high-entropy ceramic phase is (Ti 0.3 Ta 0.2 W 0.25 Nb 0.15 Zr 0.1 (C) 0.7 N 0.3 ); The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1.8:1; The auxiliary sintering phases are Mo2C and Cr3C2, with a mass fraction ratio of Mo2C to Cr3C2 of 3.5:1; The method for preparing the cutting tool material in this embodiment includes the following steps: (1) Weigh each raw material powder according to the set component ratio. The raw material powder includes TiN, TaC, NbC, ZrC, Mo2C, Cr3C2, WC, Co and carbonyl Ni powder. The Fisher particle size of TiN, TaC, NbC, ZrC, Mo2C, Cr3C2 and Co powders is not greater than 1.5 μm, the Fisher particle size of carbonyl Ni powder is not greater than 2.5 μm, and the average particle size of WC powder with specific surface area is not greater than 0.3 μm. (2) A tilting ball mill was used with alcohol as the wet grinding medium. PPG 4000 (2.0% of the total mass of the raw material powder) and PVAm 50000 (0.10% of the total mass of the raw material powder) were added as forming agent and dispersant, respectively. The mixture was wet-milled to obtain a mixture. Carbide grinding balls were used for wet milling, with a ball-to-material mass ratio of 4:1 and a wet milling time of 60 hours. (3) Spray dry the mixture into granules (150℃ in the granulation tower, spray residence time of wet material for 36s, control the flowability to 45-55 s / 50g, the same below), and then use a molding process (stroke ratio 48, control the pressing force to 39.2-49N, the same below) to prepare cutting blades (see schematic diagram of blade structure). Figure 1 (The same below), and then placed in a pressure sintering furnace with rapid cooling function for degreasing treatment (holding at 800℃ for 2H, the same below) to remove the forming agent and dispersant; (4) After degreasing, the furnace temperature is raised to 1320℃, and high-purity nitrogen and high-purity argon are introduced in a 2:1 ratio to make the pressure inside the sintering furnace reach 50Pa. This pressure is maintained until the temperature inside the sintering furnace reaches the sintering temperature of 1500℃. Then, after holding at the sintering temperature of 1500℃ for 20 minutes, high-purity argon is introduced to raise the pressure inside the furnace to 2kPa, and the temperature is held for another 70 minutes. (5) After the heat preservation is completed, the rapid cooling function of the sintering furnace is called to cool the furnace temperature to 1200°C within 1 hour, and then the furnace is cooled to a furnace exit temperature of less than 70°C to obtain high entropy metal ceramic tool material for hardened steel processing.

[0031] Example 2 In this embodiment, the binder phase content of the tool material is 19% by mass fraction, the auxiliary sintering phase content is 4.5%, and the balance is a high-entropy ceramic phase with an alloy composition of 76.5 wt.% (Ti). 0.2 Ta 0.2 W 0.25 Nb 0.15 Zr 0.2 (C) 0.8 N 0.2 -12wt.%Co-7wt.%Ni-3wt.%Mo2C-1.5wt.%Cr3C2, that is: The high-entropy ceramic phase is (Ti 0.2 Ta 0.2 W 0.25 Nb 0.15 Zr 0.2 (C) 0.8 N 0.2 ); The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1.7:1; The auxiliary sintering phases are Mo2C and Cr3C2, with a mass fraction ratio of Mo2C to Cr3C2 of 2:1. The method for preparing the cutting tool material in this embodiment includes the following steps: (1) Weigh each raw material powder according to the set component ratio. The raw material powder includes TiN, TaC, NbC, ZrC, Mo2C, Cr3C2, WC, Co and carbonyl Ni powder. The Fisher particle size of TiN, TaC, NbC, ZrC, Mo2C, Cr3C2 and Co powders is not greater than 1.5 μm, the Fisher particle size of carbonyl Ni powder is not greater than 2.5 μm, and the average particle size of WC powder with specific surface area is not greater than 0.3 μm. (2) A tilting ball mill was used with alcohol as the wet grinding medium. PPG 4000 (2.3% of the total mass of the raw material powder) and PVAm 50000 (0.05% of the total mass of the raw material powder) were added as forming agent and dispersant, respectively. The mixture was wet-milled to obtain a mixture. Hard alloy grinding balls were used for wet milling. The ball-to-material mass ratio was 5:1 and the wet milling time was 66 hours. (3) The mixture is spray-dried and granulated, and then the cutting blade is prepared by molding process. Then it is placed in a pressure sintering furnace with rapid cooling function for degreasing treatment to remove the forming agent and dispersant; (4) After degreasing, the furnace temperature is raised to 1250℃, and high-purity nitrogen and high-purity argon are introduced in a 2:1 ratio to make the pressure inside the sintering furnace reach 50Pa. This pressure is maintained until the temperature inside the sintering furnace reaches the sintering temperature of 1525℃. Then, after holding at the sintering temperature of 1525℃ for 30 minutes, high-purity argon is introduced to raise the pressure inside the furnace to 1.5kPa, and the temperature is held for another 80 minutes. (5) After the heat preservation is completed, the rapid cooling function of the sintering furnace is called to cool the furnace temperature to 1200°C within 1 hour, and then the furnace is cooled to a furnace exit temperature of less than 70°C to obtain high entropy metal ceramic tool material for hardened steel processing.

[0032] Example 3 In this embodiment, the binder phase content of the tool material is 15% by mass fraction, the auxiliary sintering phase content is 5.0%, and the balance is a high-entropy ceramic phase with an alloy composition of 80 wt.% (Ti). 0.3 Ta 0.15 W 0.25 Nb 0.15 Zr 0.15 (C) 0.7 N 0.3 )-9wt.%Co-6wt.%Ni-3.5wt.%Mo2C-1.5wt.%Cr3C2, that is: The high-entropy ceramic phase is (Ti 0.3 Ta 0.15 W 0.25 Nb 0.15 Zr 0.15 (C) 0.7 N 0.3 ); The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1.5:1; The auxiliary sintering phases are Mo2C and Cr3C2, with a mass fraction ratio of Mo2C to Cr3C2 of 2.3:1; The method for preparing the cutting tool material in this embodiment includes the following steps: (1) Weigh each raw material powder according to the set component ratio. The raw material powder includes TiN, TaC, NbC, ZrC, Mo2C, Cr3C2, WC, Co and carbonyl Ni powder. The Fisher particle size of TiN, TaC, NbC, ZrC, Mo2C, Cr3C2 and Co powders is not greater than 1.5 μm, the Fisher particle size of carbonyl Ni powder is not greater than 2.5 μm, and the average particle size of WC powder with specific surface area is not greater than 0.3 μm. (2) A tilting ball mill was used with alcohol as the wet grinding medium. PPG 4000 (2.2% of the total mass of the raw material powder) and PVAm 50000 (0.08% of the total mass of the raw material powder) were added as forming agent and dispersant, respectively. The mixture was wet-milled to obtain a mixture. Carbide grinding balls were used for wet milling, with a ball-to-material mass ratio of 4:1 and a wet milling time of 72 hours. (3) The mixture is spray-dried and granulated, and then the cutting blade is prepared by molding process. Then it is placed in a pressure sintering furnace with rapid cooling function for degreasing treatment to remove the forming agent and dispersant; (4) After degreasing, the furnace temperature is raised to 1350℃, and high-purity nitrogen and high-purity argon are introduced in a 2:1 ratio to make the pressure inside the sintering furnace reach 50Pa. This pressure is maintained until the temperature inside the sintering furnace reaches the sintering temperature of 1500℃. Then, after holding at the sintering temperature of 1500℃ for 20 minutes, high-purity argon is introduced to raise the pressure inside the furnace to 2.5kPa, and the temperature is held for another 60 minutes. (5) After the heat preservation is completed, the rapid cooling function of the sintering furnace is called to cool the furnace temperature to 1200°C within 1 hour, and then the furnace is cooled to a furnace exit temperature of less than 70°C to obtain high entropy metal ceramic tool material for hardened steel processing.

[0033] Comparative Example 1 By mass fraction, the binder phase content of the tool material in this comparative example is 14%, the auxiliary sintering phase content is 4%, and the balance is a high-entropy ceramic phase, with an alloy composition of 82 wt.% (Ti). 0.3 Ta 0.3 W 0.25 Nb 0.15 (C) 0.8 N 0.2 -7wt.% Co-7wt.% Ni-3.0wt.% Mo2C -1.0wt.% Cr3C2, that is: The high-entropy ceramic phase is (Ti 0.3 Ta 0.3 W 0.25 Nb 0.15 (C) 0.8 N 0.2 ); The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1:1; The auxiliary sintering phases are Mo2C and Cr3C2, with a mass fraction ratio of Mo2C to Cr3C2 of 3:1. Weigh each raw material powder according to the set component ratio. The preparation method of the tool material in this comparative example is the same as that in Example 1.

[0034] Comparative Example 2 By mass fraction, the binder phase content of the tool material in this comparative example is 14%, the auxiliary sintering phase content is 5.0%, and the balance is a high-entropy ceramic phase, with an alloy composition of 81 wt.% (Ti). 0.3 Ta 0.2 W 0.20 Nb 0.15 Zr 0.15 (C) 0.7 N 0.3 -5wt.% Co-9wt.% Ni-3.5wt.% Mo2C -1.5wt.% Cr3C2, that is: The high-entropy ceramic phase is (Ti 0.3 Ta 0.2 W 0.20 Nb 0.15 Zr 0.15 (C) 0.7 N 0.3 ); The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of approximately 0.56:1; The auxiliary sintering phases are Mo2C and Cr3C2, with a mass fraction ratio of Mo2C to Cr3C2 of approximately 2.3:1; Weigh each raw material powder according to the set component ratio. The preparation method of the tool material in this comparative example is the same as that in Example 1.

[0035] Comparative Example 3 By mass fraction, the binder phase content of the tool material in this comparative example is 14%, the auxiliary sintering phase content is 4.0%, and the balance is a high-entropy ceramic phase, with an alloy composition of 81 wt.% (Ti). 0.3 Ta 0.2 W 0.20 Nb 0.15 Zr 0.15 (C) 0.7 N 0.3 )-9wt.%Co-5wt.%Ni-1.5wt.%Mo2C-2.5wt.%Cr3C2, that is: The high-entropy ceramic phase is (Ti 0.3 Ta 0.2 W 0.20 Nb 0.15Zr 0.15 (C) 0.7 N 0.3 ); The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1.8:1; The auxiliary sintering phases are Mo2C and Cr3C2, with a mass fraction ratio of Mo2C to Cr3C2 of 0.6:1; Weigh each raw material powder according to the set component ratio. The preparation method of the tool material in this comparative example is the same as that in Example 1.

[0036] Comparative Example 4 Same as Example 1, except that the amount of PPG 4000 added is 1.0% of the total mass of the raw material powder, and the amount of PVAm 50000 added is 0.15% of the total mass of the raw material powder. The rest of the steps are the same as in Example 1.

[0037] Comparative Example 5 Same as Example 1, except that in step (4), after degreasing, the furnace temperature is raised to 1320°C, and high-purity nitrogen and high-purity argon are introduced in a 1:1 ratio to make the pressure inside the sintering furnace reach 50Pa. The remaining steps are consistent with Example 1.

[0038] Comparative Example 6 Same as Example 1, except that in step (4), after degreasing, the furnace temperature is raised to 1320°C, and high-purity nitrogen and high-purity argon in a 2:1 ratio are introduced to make the pressure inside the sintering furnace reach 50Pa. This pressure is maintained until the temperature inside the sintering furnace reaches the sintering temperature of 1500°C. Then, after holding at the sintering temperature of 1500°C for 10 minutes, high-purity argon is introduced to raise the pressure inside the furnace to 2kPa, and the holding time is continued for 90 minutes. The remaining steps are consistent with Example 1.

[0039] Performance testing The material being processed is water-quenched wear-resistant steel with the following composition: 1.260% Mn, 1.154% Cr, 0.296% C, 0.249% Ni, 0.115% Si, 0.002% Al, 0.021% Cu, 0.019% P, 0.004% Ca, 0.003% Co, 0.016% Ti, 0.015% Mo, 0.051% S, with the balance being Fe.

[0040] The machine tool used for turning water-quenched wear-resistant steel is a KIWA Triple 21. The machining method is hard turning of a single workpiece. The cutting parameters are as follows: cutting speed Vc = 150 m / min, feed rate fn = 0.08 mm / rev, depth of cut ap = 0.2 mm. For each batch of test inserts, 6 inserts are randomly selected for testing. The average life of the inserts is compared by the number of workpieces machined before the insert chipps.

[0041] The reference objects are commercial metal-ceramic cutting tools and commercial PCBN superhard cutting tools produced by well-known domestic enterprises.

[0042] The test results of fracture toughness and number of processed workpieces for each embodiment and comparative example are shown in Table 1.

[0043] Table 1 As can be seen from Table 1, the fracture toughness and the number of workpieces that can be machined from water-quenched wear-resistant steel in Examples 1 to 3 of the present invention are significantly better than those of commercial cermet tools and commercial PCBN superhard tools. This indicates that the present invention, through the synergistic design of high-entropy ceramic phase and Co-Ni composite binder phase, significantly improves fracture toughness while maintaining a machining life comparable to PCBN, and effectively suppresses chipping failure. Further comparison of the comparative examples reveals that: Comparative Example 1, without Zr, exhibits a fracture toughness of 4.70 and a number of workpieces of 25.5, indicating that the introduction of Zr significantly improves the fracture toughness of the material through lattice distortion; Comparative Example 2, with a Co / Ni mass fraction ratio deviating from the range of 1–2, shows a sharp decrease in fracture toughness to 4.29 and a number of workpieces of only 22.5, demonstrating that an imbalance in the binder phase ratio weakens the interfacial bonding force; Comparative Example 3, with a Mo2C / Cr3C2 mass fraction ratio deviating from the range of 2–4, has a fracture toughness of 4.33 and a number of workpieces of 27, indicating that an imbalance in the auxiliary sintering phase ratio affects the wettability of the liquid phase sintering and the carbon-nitrogen balance; the forming agent PPG 4000 and the dispersant PVAm... Comparative Example 4, where the addition amount of 50,000 deviated from the appropriate range (the addition amount of polypropylene glycol was 2.0% to 2.3% of the total mass of the raw material powder, and the addition amount of polyethyleneamine was 0.05% to 0.10% of the total mass of the raw material powder), showed a fracture toughness of 4.46 and the number of workpieces processed by all the blades was less than 20, reflecting that uneven dispersion of the wet grinding mixture can introduce internal defects. Comparative Example 5, where the N2 / Ar ratio was changed from 2:1 to 1:1 during segmented atmosphere sintering, showed a fracture toughness of 4.22 and some blades chipped when processing less than 20 workpieces, proving that the 2:1 N2 / Ar ratio accurately controlled the nitrogen partial pressure during sintering and maintained the carbon-nitrogen stoichiometry of the high-entropy ceramic phase (C,N). Comparative Example 6, where the sintering holding time deviated from the optimal range, showed a fracture toughness of 4.95 and only 23 workpieces processed, indicating that both excessively long and short holding times are not conducive to the balance between densification and grain size.

[0044] In summary, the design of each component in this invention (Zr addition, Co / Ni ratio, Mo2C / Cr3C2 ratio) and the process parameters (forming agent / dispersant ratio, N2 / Ar atmosphere ratio, sintering holding time) have a strict synergistic matching relationship. Deviation of any element will lead to a significant decrease in fracture toughness and cutting life. This proves that the technical solution of this invention, as a whole, achieves a synergistic technical effect of high toughness and long cutting life. Moreover, the results of each embodiment are highly consistent, demonstrating good process robustness and repeatability.

[0045] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-entropy cermet tool material for machining hardened steel, characterized in that, The cutting tool material comprises a high-entropy ceramic phase, a binder phase, and an auxiliary sintering phase; The high-entropy ceramic phase has the general formula (Ti) a ,Ta b W c ,Nb d ,Zr e (C) x N y ), where a, b, c, d, and e are the atomic fractions of Ti, Ta, W, Nb, and Zr, respectively, satisfying a+b+c+d+e=1, and a, b, c, d, and e are all greater than 0; x and y are the atomic fractions of C and N, respectively, satisfying x+y=1; The binder phase is a composite binder phase of Co and Ni, with a mass fraction ratio of Co to Ni of 1 to 2:1; The auxiliary sintering phase is Mo2C and Cr3C2, and the mass fraction ratio of Mo2C to Cr3C2 is 2 to 4:

1. By mass fraction, the binder phase content in the tool material is 12% to 19%, the auxiliary sintering phase content is 2% to 5%, and the balance is a high-entropy ceramic phase.

2. A method for preparing the high-entropy cermet tool material for machining hardened steel as described in claim 1, characterized in that, Includes the following steps: (1) Weigh each raw material powder according to the set component ratio, wherein the raw material powder includes TiN, TaC, NbC, ZrC, Mo2C, Cr3C2, WC, Co and carbonyl Ni powder; (2) Using alcohol as the wet grinding medium, polypropylene glycol and polyethyleneamine are added as forming agent and dispersant, respectively, and wet grinding is carried out to obtain a mixture; (3) After the mixture is spray-dried, granulated and molded, it is placed in a pressure sintering furnace with rapid cooling function for degreasing treatment; (4) After degreasing, vacuum sintering and heat preservation are carried out; (5) After the heat preservation is completed, the material is rapidly cooled and then removed from the furnace to obtain the high-entropy metal ceramic tool material for processing hardened steel.

3. The method for preparing the high-entropy cermet tool material for machining hardened steel according to claim 2, characterized in that, The raw material powders have a Fisher particle size of no more than 1.5 μm for TiN, TaC, NbC, ZrC, Mo2C, Cr3C2 and Co powders, a Fisher particle size of no more than 2.5 μm for carbonyl Ni powder, and an average particle size of no more than 0.3 μm for WC powder.

4. The method for preparing the high-entropy cermet tool material for machining hardened steel according to claim 2, characterized in that, The amount of polypropylene glycol added is 2.0% to 2.3% of the total mass of the raw material powder, and the amount of polyethyleneamine added is 0.05% to 0.10% of the total mass of the raw material powder.

5. The method for preparing the high-entropy cermet tool material for machining hardened steel according to claim 2, characterized in that, The vacuum sintering process includes: holding the furnace at a sintering temperature of 1490℃~1530℃ for 20~30 minutes, then introducing inert gas to increase the pressure inside the furnace to 1.5kPa~2.5kPa, and continuing to hold the furnace at this temperature for 60~80 minutes.

6. The method for preparing the high-entropy cermet cutting tool material for machining hardened steel according to claim 5, characterized in that, Before vacuum sintering, the process includes raising the furnace temperature to 1200℃~1350℃, introducing inert gas to make the furnace pressure reach 50Pa, and continuing to raise the temperature to a sintering temperature of 1490℃~1530℃.

7. The method for preparing the high-entropy cermet tool material for machining hardened steel according to claim 6, characterized in that, The inert gas is nitrogen and argon in a volume ratio of 2:

1.

8. The method for preparing the high-entropy cermet cutting tool material for machining hardened steel according to claim 2, characterized in that, The rapid cooling process involves cooling the furnace temperature to 1200°C within 1 hour, followed by further cooling to below 70°C before exiting the furnace.

9. The method for preparing the high-entropy cermet cutting tool material for machining hardened steel according to claim 2, characterized in that, The ball-to-material mass ratio for wet milling is (4:1) to (5:1), and the wet milling time is 60 to 72 hours.

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