A cutting tool material containing gradient high-entropy cemented carbide and its preparation method

Abstract

This invention relates to a cutting tool material containing a gradient high-entropy cemented carbide and its preparation method, belonging to the field of cemented carbide material technology. The cutting tool material has a symmetrical five-layer structure, consisting of a surface layer, a transition layer, a core layer, another transition layer, and a surface layer. The surface layer comprises 93.8–96.9 parts by mass of high-entropy carbide, 2.9–6 parts by mass of high-entropy alloy, and 0.1–0.2 parts by mass of graphene. The transition layer comprises 30–45 parts by mass of high-entropy carbide, 5–10 parts by mass of high-entropy alloy, and 45–65 parts by mass of WC hard phase. The core layer comprises 10–15 parts by mass of high-entropy alloy and 85–90 parts by mass of WC hard phase. This invention reduces the resource consumption of W and Co; it improves heat resistance by correlating the high configurational entropy mechanism for reduced thermal conductivity with the anisotropic thermal conductivity of multilayer graphene; and it achieves a high-hardness, high-strength, and high-toughness gradient high-entropy cemented carbide cutting tool material through a rational arrangement of the mechanical properties of different layers.

Description

Technical Field

[0001] This invention belongs to the field of cemented carbide materials technology, specifically relating to a cutting tool material containing gradient high-entropy cemented carbide and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Carbide cutting tools are the leading tools used in digital manufacturing. However, the "macro-homogeneous" structure, contradictory mechanical properties (difficulty in balancing hardness and toughness, wear resistance and strength), and insufficient high-temperature performance of traditional WC-Co carbide cutting tools make them unsuitable for high-speed cutting processes under multi-scale, non-uniform thermo-mechanical-chemical multi-field coupling and interaction.

[0004] Furthermore, W and Co are expensive, and their prices continue to rise. Developing new WC-replacement hard phases and Co-replacement binder phases is one of the fundamental prerequisites for achieving sustainable development of high-performance cemented carbide tools and providing them with high-quality, high-efficiency, and green cutting capabilities. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the purpose of this invention is to provide a cutting tool material containing gradient high-entropy cemented carbide and a preparation method thereof, wherein the obtained cutting tool material has high heat resistance, high hardness, and high strength and toughness.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] Firstly, a tool material containing gradient high-entropy cemented carbide has a symmetrical five-layer structure, consisting of a surface layer, a transition layer, a core layer, a transition layer, and a surface layer, in sequence.

[0008] The surface layer comprises, by mass, 93.8–96.9 parts of high-entropy carbide, 2.9–6 parts of high-entropy alloy, and 0.1–0.2 parts of graphene;

[0009] The transition layer comprises, by mass, 30-45 parts of high-entropy carbide, 5-10 parts of high-entropy alloy, and 45-65 parts of WC hard phase;

[0010] The core layer comprises 10-15 parts by mass of high-entropy alloy and 85-90 parts by mass of WC hard phase;

[0011] Optionally, the high-entropy carbide includes any five of the following in equimolar ratio: TaC, NbC, TiC, HfC, ZrC, WC, ZrC, and VC.

[0012] The high-entropy alloy includes any five of the following in equimolar ratios: Fe, Co, Ni, Cr, Mn, and Al.

[0013] Secondly, the preparation method of the aforementioned tool material containing gradient high-entropy cemented carbide includes the following steps:

[0014] 1) Weigh five kinds of carbide powders according to equimolar ratio, dry grind them to prepare a high-entropy carbide suspension, disperse them in a water bath, wet grind them, dry and sieve them to obtain high-entropy carbide powder.

[0015] 2) Weigh five metal powders in equal molar ratio, dry grind them to prepare a high-entropy alloy suspension, wet grind them, dry and sieve them to obtain high-entropy alloy powder;

[0016] 3) Graphene is added to a dispersing solvent and a dispersant to form a suspension, which is then dispersed by heating in a water bath to obtain a graphene suspension;

[0017] 4) The surface material is composed of 93.8-96.9 parts by mass of high-entropy carbide, 2.9-6 parts by mass of high-entropy alloy, and 0.1-0.2 parts by mass of graphene; the transition layer is composed of 30-45 parts by mass of high-entropy carbide, 5-10 parts by mass of high-entropy alloy, and 45-65 parts by mass of WC hard phase; and the core layer is composed of 10-15 parts by mass of high-entropy alloy and 85-90 parts by mass of WC hard phase. The materials of each layer are prepared into mixed powder suspensions according to the proportions, ball-milled, dried, and sieved to obtain well-dispersed gradient layer powders.

[0018] 5) The layered pressing method is used to press five layers of gradient material into shape, and a liquid phase + solid phase two-step discharge plasma sintering process is used to obtain tool material containing gradient high-entropy cemented carbide.

[0019] Optionally, all five carbide powders are submicron-sized powders, including any five of TaC, NbC, TiC, HfC, ZrC, WC, ZrC, and VC in equimolar ratios;

[0020] All five metal powders are submicron-sized powders, including any five of Fe, Co, Ni, Cr, Mn, and Al in equimolar ratios.

[0021] Optionally, in step 1), the dry grinding time is 2 hours, with 5 minutes of grinding followed by a 2-minute break; after dry grinding, anhydrous ethanol is added as the dispersion solvent and polyethylene glycol as the dispersion medium to prepare a high-entropy carbide suspension; the suspension is then ultrasonically dispersed in a 100°C water bath for 1 hour, followed by wet grinding for 24 hours, and then dried in a vacuum drying oven. After sieving, well-dispersed high-entropy carbide powder is obtained.

[0022] Optionally, in step 2), the dry grinding time is 2 hours, with 5 minutes of grinding followed by a 2-minute break; after dry grinding, anhydrous ethanol is added as the dispersion solvent and polyethylene glycol as the dispersion medium to prepare a high-entropy alloy suspension; the suspension is then ultrasonically dispersed in a 100°C water bath for 1 hour, followed by wet grinding for 24 hours, and then dried in a vacuum drying oven. After sieving, well-dispersed high-entropy alloy powder is obtained.

[0023] Optionally, in step 3), the dispersing solvent is anhydrous ethanol; the dispersant is a compound dispersant of polyethylene glycol and polyvinylpyrrolidone in a ratio of 1:1, and the amount of compound dispersant added is 80% of the mass of graphene; the dispersant is ultrasonically dispersed in a water bath at 100°C for 60 min.

[0024] Optionally, in step 4), WC powder, high-entropy carbide powder, high-entropy alloy powder and / or graphene suspension are mixed and ultrasonically dispersed in a water bath for 30 minutes to obtain a mixed powder suspension.

[0025] Alternatively, the high-entropy alloy is added to a dispersing solvent (anhydrous ethanol) and a dispersant (polyethylene glycol) to form a suspension. The suspension is then ultrasonically dispersed in a water bath for 30 minutes to obtain a high-entropy alloy suspension. High-entropy carbides are then added, and the suspension is ultrasonically dispersed in a water bath for another 30 minutes. Finally, WC powder is added, and the suspension is ultrasonically dispersed in a water bath for another 30 minutes to obtain a mixed powder suspension.

[0026] In a mixed powder suspension, grinding balls are added at a certain ball-to-powder ratio, and the mixture is ball-milled for 30 hours. Then, it is dried in a vacuum drying oven and sieved to obtain well-dispersed powders of various gradient layers.

[0027] Optionally, in step 5), the weight of each gradient layer powder is calculated based on the mold size and gradient layer thickness. The 5-layer gradient powder is pressed into shape using a layered pressing method. A two-step discharge plasma sintering process of liquid phase + solid phase is adopted: the vacuum degree is maintained below 10 Pa, the temperature is increased to 1400-1550℃ at 150℃ / min, held for 1-5 min, then cooled to 1300-1350℃ at 150℃ / min, held for 1-6 h, and then cooled with the furnace.

[0028] During the heating and cooling processes, the pressure is maintained at 20 MPa from room temperature to 1200℃, and at 45 MPa from 1200 to 1550℃.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. This invention introduces high-entropy carbides as a hard phase to replace WC and high-entropy alloys as a binder phase to replace Co, thereby reducing the resource consumption of W and Co.

[0031] 2. This invention introduces multilayer graphene as a lubricating and heat-insulating phase on the surface. It correlates the high configurational entropy mechanism that reduces thermal conductivity with the anisotropic thermal conductivity of multilayer graphene, effectively reducing the surface thermal conductivity and making the surface heat-resistant and insulating. As a cutting tool rake face, it effectively prevents cutting heat from being transferred to the tool body, resulting in high overall heat resistance for the tool material.

[0032] 3. In this invention, the content of high-entropy carbides decreases from the surface to the core, while the content of WC increases from the surface to the core. That is, high-entropy carbides gradually replace the traditional WC hard phase from the core to the surface, achieving a high-hardness configuration on the tool surface. The content of high-entropy alloy increases from the surface to the core, achieving a high-toughness configuration in the tool core. By combining the high hardness of high-entropy carbides with the high toughness of high-entropy alloys, and rationally arranging the mechanical properties of different layers, a high-heat-resistant, high-hardness, and high-strength-toughness gradient high-entropy cemented carbide tool material is obtained.

[0033] 4. This invention employs a two-step discharge plasma sintering process consisting of liquid phase and solid phase, providing a technology for the industrial production of high-heat-resistant, high-hardness, high-strength-toughness gradient high-entropy cemented carbide tool materials. Detailed Implementation

[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] This invention provides a tool material containing a gradient high-entropy cemented carbide, comprising five symmetrical layers from top to bottom: a surface layer, a transition layer, a core layer, another transition layer, and a surface layer.

[0037] The surface layer comprises, by mass, 93.8–96.9 parts of high-entropy carbide, 2.9–6 parts of high-entropy alloy, and 0.1–0.2 parts of graphene;

[0038] The transition layer comprises 30-45 parts by mass of high-entropy carbide, 5-10 parts by mass of high-entropy alloy, and 45-65 parts by mass of WC hard phase;

[0039] The core layer comprises 10-15 parts by mass of high-entropy alloy and 85-90 parts by mass of WC hard phase;

[0040] High-entropy carbides include any five of the following in equimolar ratio: TaC, NbC, TiC, HfC, ZrC, WC, ZrC, and VC.

[0041] High-entropy alloys include any five of the following in equimolar ratios: Fe, Co, Ni, Cr, Mn, and Al.

[0042] The reason for retaining a certain amount of WC hard phase is that if it is completely replaced with high-entropy carbides, the material has good hardness and toughness, but insufficient bending strength. Retaining a portion of WC hard phase in the core layer and transition layer allows the material to have both high hardness and high toughness, as well as excellent bending strength.

[0043] High-entropy carbides, acting as a hard phase to replace WC, and high-entropy alloys, acting as a binder phase to replace Co, reduce the resource consumption of W and Co. Simultaneously, the mechanism of high configurational entropy reducing thermal conductivity is designed in conjunction with the anisotropic thermal conductivity of multilayer graphene, effectively reducing surface thermal conductivity and preventing a large amount of cutting heat from transferring into the core layer. The high-entropy alloy, as a binder phase, exhibits stable high-temperature properties, which also contributes to improving the high-temperature resistance of tool materials.

[0044] The present invention also provides a method for preparing the above-mentioned tool material containing gradient high-entropy cemented carbide, comprising the following steps:

[0045] 1) Weigh five carbide powders according to equimolar ratio, first dry grind for 2 hours (grind for 5 minutes, stop for 2 minutes), then add anhydrous ethanol as the dispersion solvent and polyethylene glycol as the dispersion medium to prepare a high-entropy carbide suspension, heat in a water bath at 100℃ and ultrasonically disperse for 1 hour; after wet grinding for 24 hours, dry in a vacuum drying oven and sieve to obtain well dispersed high-entropy carbide powder;

[0046] 2) Weigh five metal powders according to equimolar ratio, first dry grind for 2 hours (grind for 5 minutes, stop for 2 minutes), then add anhydrous ethanol as dispersion solvent and polyethylene glycol as dispersion medium to prepare a high entropy alloy suspension, heat in a water bath at 100℃ and ultrasonically disperse for 1 hour; after wet grinding for 24 hours, dry in a vacuum drying oven and sieve to obtain well dispersed high entropy alloy powder;

[0047] 3) Graphene was added to anhydrous ethanol as a dispersion solvent, and 80% of the graphene mass of a compound dispersant (polyethylene glycol: polyvinylpyrrolidone = 1:1) was added to prepare a suspension. The suspension was then ultrasonically dispersed in a water bath at 100°C for 60 minutes to obtain a graphene suspension.

[0048] 4) The surface material is composed of 93.8-96.9 parts by mass of high-entropy carbide, 2.9-6 parts by mass of high-entropy alloy, and 0.1-0.2 parts by mass of graphene; the transition layer is composed of 30-45 parts by mass of high-entropy carbide, 5-10 parts by mass of high-entropy alloy, and 45-65 parts by mass of WC hard phase; and the core layer is composed of 10-15 parts by mass of high-entropy alloy and 85-90 parts by mass of WC hard phase.

[0049] WC powder, high-entropy carbide powder, high-entropy alloy powder and / or graphene suspension are mixed and ultrasonically dispersed in a water bath at 100°C for 30 min to obtain a mixed powder suspension.

[0050] Alternatively, anhydrous ethanol is added to the high-entropy alloy as a dispersion solvent, polyethylene glycol is added as a dispersant, and the mixture is ultrasonically dispersed in a water bath at 100°C for 30 minutes to obtain a high-entropy alloy suspension; then high-entropy carbide is added, and the mixture is ultrasonically dispersed in a water bath at 100°C for 30 minutes; then WC powder is added, and the mixture is ultrasonically dispersed in a water bath at 100°C for 30 minutes to obtain a mixed powder suspension.

[0051] According to the proportion of each gradient layer material, a mixed powder suspension of each gradient layer material was obtained. Grinding balls were added in a certain proportion, and the mixture was ball-milled for 30 hours, then dried and sieved to obtain well dispersed powders of each gradient layer.

[0052] 5) Calculate the powder weight of each gradient layer based on the mold size and gradient layer thickness of the tool material. Use a layered pressing method to load the material and press the five gradient powder materials into shape. Use a liquid phase + solid phase two-step discharge plasma sintering process: maintain the vacuum degree below 10 Pa, heat to 1400-1550℃ at 150℃ / min, hold for 1-5 min; cool to 1300-1350℃ at 150℃ / min, hold for 1-6 h; then cool with the furnace.

[0053] During the heating and cooling processes, the pressure is maintained at 20 MPa from room temperature to 1200℃, and at 45 MPa from 1200 to 1550℃, to obtain a tool material containing gradient high-entropy cemented carbide.

[0054] In the two-step discharge plasma sintering process of liquid phase + solid phase: the first step is short-time liquid phase sintering, which initially forms single-phase high-entropy alloy and single-phase high-entropy carbide. The high-entropy alloy generates a liquid phase, which forms good wetting of high-entropy carbide and WC, and achieves rapid improvement in the density of the tool material; the second step is long-time low-temperature solid phase sintering, in which the high-entropy alloy and high-entropy carbide components undergo further diffusion and homogenization based on the concentration difference, thereby improving the density of the tool material without grain growth.

[0055] Preferably, all five carbide powders are submicron-sized powders, including any five of TaC, NbC, TiC, HfC, ZrC, WC, ZrC, and VC in equimolar ratios;

[0056] All five metal powders are submicron-sized powders, including any five of Fe, Co, Ni, Cr, Mn, and Al in equimolar ratios;

[0057] Choosing submicron-sized powders can reduce the grain size of sintered products, which helps to densify high-entropy carbides and high-entropy alloys and form single-phase solid solutions, thereby improving the mechanical properties of tool materials.

[0058] Example 1

[0059] 1) Using five types of carbide ceramic powders (0.4 μm HfC, ZrC, TaC, NbC, and TiC) as raw materials, they were prepared in equimolar ratios. First, dry milling was performed for 2 hours (milling for 5 minutes, stopping for 2 minutes). Then, anhydrous ethanol was added as the dispersion solvent and polyethylene glycol as the dispersion medium to prepare a high-entropy carbide suspension. The suspension was ultrasonically dispersed in a water bath at 100°C for 1 hour, followed by wet milling for 24 hours. Finally, the suspension was dried in a vacuum drying oven and sieved to obtain well-dispersed high-entropy carbide powder.

[0060] 2) Using five metal powders (0.5μm Fe, Co, Ni, Cr, and Al) as raw materials, they were prepared in equimolar ratios. First, dry grinding was carried out for 2 hours (grinding for 5 minutes, stopping for 2 minutes). Then, anhydrous ethanol was added as the dispersion solvent and polyethylene glycol as the dispersion medium to prepare a high-entropy alloy suspension. The suspension was ultrasonically dispersed in a water bath at 100℃ for 1 hour, followed by wet grinding for 24 hours. Finally, the suspension was dried in a vacuum drying oven and sieved to obtain well-dispersed high-entropy alloy powder.

[0061] 3) Graphene dispersion was carried out using anhydrous ethanol as the dispersion solvent. 80% of the relative mass of graphene was added to prepare a suspension, which was then ultrasonically dispersed in a water bath at 100°C for 60 minutes.

[0062] 4) Using high-entropy carbide powder, high-entropy alloy powder, 0.4μm tungsten carbide (WC) powder and graphene suspension as raw materials, the surface layer is formulated with 94.9 parts of high-entropy carbide powder, 5 parts of high-entropy alloy powder and 0.1 parts of graphene by mass; the transition layer is formulated with 45 parts of WC powder, 45 parts of high-entropy carbide powder and 10 parts of 10 high-entropy alloy powder by mass; and the core layer is formulated with 85 parts of WC powder and 15 parts of high-entropy alloy powder by mass.

[0063] After mixing the materials of each gradient layer, the mixture is ball-milled and then ultrasonically dispersed in a water bath at 100°C for 30 minutes to obtain a powder suspension of each gradient layer. Grinding balls are added at a certain ball-to-material ratio, and the mixture is ball-milled for 30 hours. The mixture is then dried in a vacuum drying oven and sieved to obtain well-dispersed powders of each gradient layer.

[0064] 5) A two-step discharge plasma sintering process of liquid phase + solid phase is adopted: the vacuum degree is maintained below 10 Pa, the temperature is increased to 1500℃ at 150℃ / min, held for 3 min, then cooled to 1325℃ at 150℃ / min and held for 1 h, and then cooled with the furnace; the pressure is maintained at 20 MPa from room temperature to 1200℃, and at 45 MPa from 1200-1500℃ to obtain tool material A.

[0065] Example 2

[0066] The difference from Example 1 is that in step 1), five carbide ceramic powders of 0.4μm WC, ZrC, TaC, NbC and TiC are used as raw materials to obtain well dispersed high-entropy carbide powder.

[0067] In step 2), five metal powders of 0.5μm Fe, Co, Cr, Mn and Al are used as raw materials to obtain well-dispersed high-entropy alloy powder.

[0068] In step 4), high-entropy carbide powder, high-entropy alloy powder, 0.4μm tungsten carbide (WC) powder, and graphene suspension are used as raw materials. The surface layer is formulated with 93.9 parts of high-entropy carbide powder, 6 parts of high-entropy alloy powder, and 0.1 parts of graphene by mass; the transition layer is formulated with 50.5 parts of WC powder, 40.5 parts of high-entropy carbide powder, and 9 parts of high-entropy alloy powder by mass; and the core layer is formulated with 88 parts of WC powder and 12 parts of high-entropy alloy powder by mass, so as to obtain well dispersed gradient layer powders.

[0069] In step 5), the temperature is increased to 1525℃ at 150℃ / min, held for 3 min, then cooled to 1355℃ at 150℃ / min and held for 1 h, and then cooled with the furnace to obtain tool material B.

[0070] Example 3

[0071] The difference from Example 1 is that in step 1), five carbide ceramic powders of 0.4μm VC, ZrC, TaC, NbC and TiC are used as raw materials to obtain well dispersed high-entropy carbide powder.

[0072] In step 2), five metal powders of 0.5μm Fe, Co, Cr, Mn and Al are used as raw materials to obtain well-dispersed high-entropy alloy powder.

[0073] In step 4), high-entropy carbide powder, high-entropy alloy powder, 0.4μm tungsten carbide (WC) powder, and graphene suspension are used as raw materials. The surface layer is formulated with 94.85 parts of high-entropy carbide powder, 5 parts of high-entropy alloy powder, and 0.15 parts of graphene by mass; the transition layer is formulated with 45 parts of WC powder, 45 parts of high-entropy carbide powder, and 10 parts of high-entropy alloy powder by mass; and the core layer is formulated with 85 parts of WC powder and 15 parts of high-entropy alloy powder by mass, thus obtaining well-dispersed gradient layer powders.

[0074] In step 5), the temperature is increased to 1500℃ at 150℃ / min, held for 5 min, then cooled to 1300℃ at 150℃ / min and held for 2 h, and then cooled with the furnace to obtain tool material C.

[0075] Example 4

[0076] The difference from Example 1 is that in step 1), five kinds of carbide ceramic powders, namely 0.4μm HfC, ZrC, TaC, TiC and VC, are used as raw materials to obtain well dispersed high-entropy carbide powder.

[0077] In step 2), five metal powders of 0.5μm Fe, Co, Ni, Mn and Al are used as raw materials to obtain well-dispersed high-entropy alloy powder.

[0078] In step 4), high-entropy carbide powder, high-entropy alloy powder, 0.4μm tungsten carbide (WC) powder, and graphene suspension are used as raw materials. The surface layer is formulated with 96.9 parts of high-entropy carbide powder, 2.9 parts of high-entropy alloy powder, and 0.2 parts of graphene by mass; the transition layer is formulated with 65 parts of WC powder, 30 parts of high-entropy carbide powder, and 5 parts of high-entropy alloy powder by mass; and the core layer is formulated with 90 parts of WC powder and 10 parts of high-entropy alloy powder by mass, thus obtaining well-dispersed gradient layers of powder.

[0079] In step 5), the temperature is increased to 1475℃ at 150℃ / min, held for 5 min, then cooled to 1300℃ at 150℃ / min and held for 2 h, and then cooled with the furnace to obtain tool material D.

[0080] Comparative Example

[0081] 1) Instead of using high-entropy carbide powder and high-entropy alloy powder, only 0.4μm WC powder and 0.5μm Co powder are used as raw materials; WC powder and Co powder are ultrasonically dispersed to obtain WC suspension and Co suspension respectively.

[0082] 2) The surface layer is formulated with 95 parts WC powder and 5 parts Co powder by mass ratio, the transition layer with 90 parts WC powder and 10 parts Co powder by mass ratio, and the core layer with 85 parts WC powder and 15 parts Co powder by mass ratio.

[0083] Based on the proportions of the powders in each gradient layer, the two suspensions were mixed under ultrasonic and mechanical stirring conditions, and then ultrasonically dispersed in a 100℃ water bath for 30 minutes to obtain the powder suspensions for each gradient layer. Grinding balls were added at a certain ball-to-powder ratio, and the mixture was ball-milled for 30 hours. Then, the mixture was dried in a vacuum drying oven and sieved to obtain the well-dispersed powders for each gradient layer.

[0084] 3) A two-step discharge plasma sintering process of liquid phase + solid phase is adopted: the vacuum degree is maintained below 10 Pa, the temperature is increased to 1500℃ at 150℃ / min, held for 5 min, then cooled to 1300℃ at 150℃ / min and held for 2 h, and then cooled with the furnace; the pressure is maintained at 20 MPa from room temperature to 1200℃, and at 45 MPa from 1200-1500℃ to obtain tool material E.

[0085] The performance of the cutting tool materials obtained in each embodiment was tested, and the results are as follows:

[0086] Tool material A has the following mechanical properties: bending strength 1631 MPa, Vickers hardness HV. 30 2326.5 kgf / mm 2 Fracture toughness 12.7 MPa·m 1 / 2 The thermal conductivity of each layer is as follows: surface layer 12 W / (m•K), transition layer 29 W / (m•K), core layer 62 W / (m•K).

[0087] Tool material B has the following mechanical properties: bending strength 1682 MPa, Vickers hardness HV. 30 2391.4 kgf / mm 2 Fracture toughness 13.0 MPa·m 1 / 2 The thermal conductivity of each layer is as follows: surface layer 10.6 W / (m•K), transition layer 22.1 W / (m•K), core layer 41.4 W / (m•K).

[0088] Tool material C has the following mechanical properties: bending strength 1593 MPa, Vickers hardness HV. 30 2263.4 kgf / mm 2 Fracture toughness 11.7 MPa·m 1 / 2 The thermal conductivity of each layer is as follows: surface layer 7.7 W / (m•K), transition layer 23.9 W / (m•K), core layer 40.1 W / (m•K).

[0089] The tool material D has the following mechanical properties: bending strength 1559 MPa, Vickers hardness HV. 30 2371.1 kgf / mm 2 Fracture toughness 12.3 MPa·m 1 / 2The thermal conductivity of each layer is as follows: surface layer 11 W / (m•K), transition layer 33 W / (m•K), core layer 65 W / (m•K).

[0090] Tool material E has the following mechanical properties: bending strength 1439 MPa, Vickers hardness HV. 30 1625.3 kgf / mm 2 Fracture toughness 10.1 MPa·m 1 / 2 The thermal conductivity of each layer is as follows: surface layer 90.2 W / (m•K), transition layer 89.3 W / (m•K), core layer 90.7 W / (m•K).

[0091] It can be seen that the mechanical properties and heat resistance of the tool material E obtained in the comparative example are significantly lower than those of tool materials A, B, C and D obtained in Examples 1, 2, 3 and 4, and it is impossible to achieve the coupling coexistence of high hardness, high toughness and high heat resistance.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cutting tool material comprising a gradient high-entropy cemented carbide, characterized in that, The five-layer structure is symmetrical, and sequentially comprises a surface layer, a transition layer, a core layer, a transition layer and a surface layer; The surface layer is composed of high-entropy carbide 93.8-96.9 parts by mass, high-entropy alloy 2.9-6 parts by mass and graphene 0.1-0.2 parts by mass; the transition layer is composed of high-entropy carbide 30-45 parts by mass, high-entropy alloy 5-10 parts by mass and WC hard phase 45-65 parts by mass; and the core layer is composed of high-entropy alloy 10-15 parts by mass and WC hard phase 85-90 parts by mass.

2. The cemented carbide comprising a gradient high-entropy material according to claim 1, wherein, The high-entropy carbide comprises any five of TaC, NbC, TiC, HfC, WC, ZrC and VC in equal molar ratio. The high-entropy alloy comprises any five of Fe, Co, Ni, Cr, Mn and Al in equal molar ratio.

3. A method of producing a cutting tool material containing a gradient high-entropy cemented carbide according to any one of claims 1-2, characterized in that, The method comprises the steps of: 1) five kinds of carbide powders are weighed in equal molar ratio, dry grinding to prepare a high-entropy carbide suspension, water bath dispersion, wet grinding, drying and sieving to obtain high-entropy carbide powder; 2) five kinds of metal powders are weighed in equal molar ratio, dry grinding to prepare a high-entropy alloy suspension, wet grinding, drying and sieving to obtain high-entropy alloy powder; 3) graphene is added to a dispersion solvent and a dispersant to prepare a suspension, heated and dispersed in a water bath to obtain a graphene suspension; 4) the surface layer material is composed of high-entropy carbide 93.8-96.9 parts by mass, high-entropy alloy 2.9-6 parts by mass and graphene 0.1-0.2 parts by mass, the transition layer is composed of high-entropy carbide 30-45 parts by mass, high-entropy alloy 5-10 parts by mass and WC hard phase 45-65 parts by mass, and the core layer is composed of high-entropy alloy 10-15 parts by mass and WC hard phase 85-90 parts by mass; each layer of material is proportionally configured into a mixed powder suspension, ball milled, dried and sieved to obtain well-dispersed powder of each gradient layer; 5) a layered laying method is used to load and press the five layers of gradient material into a shape, and a liquid phase + solid phase two-step spark plasma sintering process is used to obtain a tool material containing gradient high-entropy hard alloy.

4. The method of producing a tool material containing a gradient high-entropy cemented carbide according to claim 3, characterized in that, In step 1), the five kinds of carbide powders are submicron powders; in step 2), the five kinds of metal powders are submicron powders.

5. The method of producing a tool material containing a gradient high-entropy cemented carbide according to claim 4, characterized in that, The powder particle size of the five kinds of carbide powders is 0.4 μm.

6. The method of claim 4, wherein the tool material comprising gradient high-entropy cemented carbide is prepared by the steps of: preparing a powder mixture comprising a plurality of powders of different compositions; and sintering the powder mixture. The powder particle size of the five kinds of metal powders is 0.5 μm.

7. The method of producing a tool material containing gradient high-entropy cemented carbide according to claim 3, characterized in that, In step 1), the dry grinding time is 2 h, grinding for 5 min and stopping for 2 min; after dry grinding, anhydrous ethanol is added as a dispersion solvent, and polyethylene glycol is added as a dispersion medium to prepare a high-entropy carbide suspension; the suspension is heated and ultrasonically dispersed in a 100℃ water bath for 1 h, then wet ground for 24 h, dried in a vacuum drying box, and sieved to obtain well-dispersed high-entropy carbide powder.

8. The method of producing a tool material containing gradient high-entropy cemented carbide according to claim 3, characterized in that, In step 2), the dry grinding time is 2 h, grinding for 5 min and stopping for 2 min; after dry grinding, anhydrous ethanol is added as a dispersion solvent, and polyethylene glycol is added as a dispersion medium to prepare a high-entropy alloy suspension; the suspension is heated and ultrasonically dispersed in a 100℃ water bath for 1 h, then wet ground for 24 h, dried in a vacuum drying box, and sieved to obtain well-dispersed high-entropy alloy powder.

9. The method of claim 3, wherein the tool material comprising gradient high-entropy cemented carbide is prepared by the steps of: preparing a powder mixture comprising a plurality of powders of different compositions; and sintering the powder mixture to form the tool material comprising gradient high-entropy cemented carbide. In step 3), the dispersion solvent is anhydrous ethanol; the dispersant is a complex dispersant of polyethylene glycol: polyvinylpyrrolidone = 1:1, and the complex dispersant is added in an amount of 80% of the mass of the graphene; and the graphene is ultrasonically dispersed in a water bath at 100 ℃ for 60 min.

10. The method of claim 3, wherein the tool material comprising gradient high-entropy cemented carbide is prepared by the steps of: preparing a powder mixture comprising a plurality of powders of different compositions; and sintering the powder mixture to form the tool material comprising gradient high-entropy cemented carbide. In step 4), each layer of material is respectively proportioned into a mixed powder suspension, and each gradient layer powder suspension is obtained by ultrasonically dispersing at 100 ℃ for 30 min. In step 5), the mill balls are added in a certain ball-to-material ratio, the balls are milled for 30 h, then dried in a vacuum drying box, and sieved to obtain each gradient layer powder with good dispersion.

11. The method of claim 3, wherein the tool material comprising gradient high-entropy cemented carbide is prepared by the steps of: preparing a powder mixture comprising a plurality of powders of different compositions; and sintering the powder mixture to form the tool material comprising gradient high-entropy cemented carbide. In step 5), the weight of each gradient layer powder is calculated according to the size of the mold and the thickness of the gradient layer, the powder is loaded by a layered pressing method, and the 5-layer gradient powder is pressed into a shape; a liquid phase + solid phase two-step spark plasma sintering process is adopted: the vacuum degree is kept below 10 Pa, the temperature is raised to 1400-1550 ℃ at a rate of 150 ℃ / min, kept for 1-5 min, then cooled to 1300-1350 ℃ at a rate of 150 ℃ / min, kept for 1-6 h, and then cooled with the furnace.

12. The method of claim 9, wherein the tool material comprising gradient high-entropy cemented carbide is prepared by the steps of: preparing a powder mixture comprising a plurality of powders of different compositions; and sintering the powder mixture to form the tool material comprising gradient high-entropy cemented carbide. During the heating and cooling processes, the pressure is kept at 20 MPa during room temperature to 1200 ℃, and the pressure is kept at 45 MPa during 1200-1550 ℃.