A high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool, its preparation method and application

Abstract

This invention belongs to the field of ceramic materials technology, and discloses a high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool, its preparation method, and its application. This high-entropy carbonitride ceramic composite cutting tool includes a high-entropy carbonitride ceramic (Ti) as the cutting tip. 0.25 Zr 0.25 Nb 0.25 Ta 0.25 C x N 1‑x The ceramic composite tool, consisting of a particle size distribution of 0.5 ≤ x ≤ 0.9 and a WC-Co cemented carbide shank, is produced by first mixing TiC, ZrC, NbC, TaC, TiN, ZrN, NbN, and TaN, and then sintering the mixture in an argon atmosphere at 1600–1800 °C to obtain a high-entropy carbonitride ceramic. Next, CuSnTi brazing filler metal is coated between the high-entropy carbonitride ceramic and the WC-Co cemented carbide, and the mixture is then welded at 880–930 °C. This high-entropy carbonitride ceramic composite tool can be used for continuous cutting of high-hardness materials such as gray cast iron and ductile iron.

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials technology, and more specifically, relates to a high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool, its preparation method and application. Background Technology

[0002] High-entropy ceramics are a novel materials design theory that has emerged in recent years and are currently a hot topic in materials research. The concept originated from high-entropy alloys. High-entropy ceramics are generally multi-component single-phase solid solutions composed of four or more cations in equal or near-equal amounts. Due to their unique "high-entropy effect," high-entropy ceramics exhibit higher strength, hardness, excellent wear resistance, excellent high-temperature strength, good structural stability, and good corrosion resistance and oxidation resistance compared to their constituent single-phase components. The increased number of components significantly expands the combinatorial space for exploring and discovering new materials. In high-entropy ceramics, the increased configurational entropy of the ceramic system due to the increased components leads to a decrease in its Gibbs free energy, making the ceramic system more stable and exhibiting excellent stability. Furthermore, because various atoms are randomly distributed in the crystal lattice, the environment and occupancy of each atom are different, resulting in more lattice distortions and defects within the crystal, making slip difficult and improving performance.

[0003] High-entropy ceramics, with their high hardness and wear resistance, hold promise as cutting tools for high-speed, long-life cutting of materials with high hardness, high cutting temperatures, and a tendency to bond, such as gray cast iron and ductile iron. However, the complex manufacturing process and high cost of high-entropy ceramics, coupled with their relatively low toughness and strength, make them difficult to directly fabricate into cutting tools. Therefore, there is an urgent need to design and develop a suitable method for their application in cutting tools. Summary of the Invention

[0004] To address the shortcomings and drawbacks of the existing technology, the primary objective of this invention is to provide a high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool, which is composed of (Ti) 0.25 Zr 0.25 Nb 0.25 Ta 0.25 C x N 1-x The tool is made of high-entropy carbonitride ceramic (0.5≤x≤0.9) and WC-Co cemented carbide. The high-entropy carbonitride ceramic has good hardness, excellent friction and wear properties and physicochemical stability. As the cutting part of the welded tool, it has good cutting performance. The WC-Co cemented carbide tool holder has high strength, which makes the tool have good resistance to chipping and breakage.

[0005] Another object of the present invention is to provide a method for preparing the aforementioned high-entropy carbonitride ceramic composite cutting tool with high hardness and high strength. This method involves welding high-entropy carbonitride ceramic together with WC-Co cemented carbide to prepare a high-entropy ceramic cutting tool with high hardness and high strength.

[0006] Another object of the present invention is to provide the application of the aforementioned high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool. This tool can be used for high-speed cutting of gray cast iron and ductile cast iron.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool, wherein the high-entropy carbonitride ceramic composite cutting tool comprises a high-entropy carbonitride ceramic (Ti) as the cutting tip. 0.25 Zr 0.25 Nb 0.25 Ta 0.25 C x N 1-x The ceramic composite tool is composed of a 0.5≤x≤0.9 and a WC-Co cemented carbide shank. It is prepared by first mixing TiC, ZrC, NbC, TaC, TiN, ZrN, NbN, and TaN, and then sintering the mixture in an argon atmosphere at 1600–1800℃ using discharge plasma sintering to obtain a high-entropy carbonitride ceramic. Next, CuSnTi brazing filler metal is coated between the high-entropy carbonitride ceramic and the WC-Co cemented carbide, and the mixture is brazed in a vacuum environment at 880–930℃ under a pressure of 200–300 N.

[0009] Preferably, the ceramic cutting tool has a Vickers hardness of 23–27 GPa and a fracture toughness of 4.0–6.0 MPa·m. 1 / 2 Its flexural strength is 1200-1500 MPa.

[0010] Preferably, the TiC, ZrC, NbC, TaC, TiN, ZrN, NbN, and TaN powders have a particle size of 0.8–4 μm and a purity greater than 99%.

[0011] Preferably, the solder is CuSnTi brazing filler metal with a thickness of 0.05 to 0.13 mm, and the welding method is brazing. The brazing process is carried out in a vacuum environment to prevent oxidation, and a pressure of 200 to 300 N is applied to ensure that a high-quality weld is formed on the connection surface.

[0012] Preferably, the heating rate of the spark plasma sintering is 50–150 °C / min; the sintering time is 10–20 min; the heating rate of the brazing furnace is 50–200 °C / min; and the sintering time is 0.5–1 h.

[0013] The preparation method of the high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool includes the following specific steps:

[0014] S1. Using anhydrous ethanol as solvent and tungsten carbide as ball milling medium, micron-sized TiC, ZrC, NbC, TaC, TiN, ZrN, NbN and TaN powders were ball-milled and then dried to obtain mixed powder;

[0015] S2. The mixed powder is loaded into a graphite mold, and under an argon atmosphere, it is pressurized at 30-50 MPa and subjected to spark plasma sintering at 1600-1800℃ to obtain high-entropy carbonitride ceramics.

[0016] S3. Coat the high-entropy carbonitride ceramic and WC-Co cemented carbide with CuSnTi brazing filler metal, dry at 80-100℃ for 1-2 hours, then put it into a mold, apply a pressure of 200-300N under vacuum, and braze at 880-930℃ to obtain a high-entropy ceramic composite tool.

[0017] The application of the high-hardness, high-strength, high-entropy carbonitride ceramic composite cutting tool in high-speed cutting of gray cast iron or ductile iron.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The high-entropy carbonitride ceramic composite tool of the present invention is composed of (Ti) 0.25 Zr 0.25 Nb 0.25 Ta 0.25 C x N 1-x The tool is made of high-entropy carbonitride ceramic (0.5≤x≤0.9) and WC-Co cemented carbide. The high-entropy carbonitride ceramic has good hardness, excellent friction and wear properties and physicochemical stability. As the cutting part of the welded tool, it has good cutting performance. The WC-Co cemented carbide tool holder has high strength, which makes the tool have good resistance to chipping and breakage.

[0020] 2. This invention introduces a key technology in the fabrication of high-entropy carbonitride ceramic composite cutting tools: high-quality welding of high-entropy carbonitride ceramics to WC-Co cemented carbide is achieved using CuSnTi solder in a vacuum environment. This step not only ensures the purity of the welding process but also maintains the inherent properties of the high-entropy ceramic while forming a tight bond with the cemented carbide, providing a solid foundation for the tool's durability and performance. Welding in a vacuum environment helps avoid the influence of oxidation and other contaminants on the weld joint, thus ensuring a purer and more reliable tool fabrication process. This is particularly crucial for materials like high-entropy carbonitride ceramics, which have high environmental requirements, effectively improving the overall quality and stability of the cutting tool.

[0021] 3. The high-entropy carbonitride ceramic composite cutting tool of this invention not only improves the overall performance of the tool but also broadens its application range. Its superior performance in cutting gray cast iron or ductile cast iron brings great convenience to industrial production and machining, efficiently meeting the machining needs of various materials, thereby improving production efficiency and reducing costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the high-entropy carbonitride ceramic composite ceramic cutting tool of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0024] Example 1

[0025] 1. Preparation

[0026] (1) Using anhydrous ethanol as solvent and tungsten carbide as the ball milling medium, TiC (purity 99.5 wt.%, particle size 1 μm), ZrC (purity 99.5 wt.%, particle size 1 μm), NbC (purity 99.5 wt.%, particle size 1 μm), TaC (purity 99 wt.%, particle size 1 μm), TiN (purity 99.5 wt.%, particle size 1 μm), ZrN (purity 99.5 wt.%, particle size 1 μm), NbN (purity 99.5 wt.%, particle size 1 μm) and TaN (purity 99.5 wt.%, particle size 1 μm) with a molar ratio of 9:9:9:9:1:1:1:1 were mixed and ball-milled at 200 r / min for 3 h. After drying and sieving, a mixed powder was obtained.

[0027] (2) The mixed powder was loaded into a graphite mold and placed in a spark plasma (SPS) sintering furnace. Under an argon atmosphere, the axial pressure was increased to 30 MPa, and the temperature was raised to 1600 °C at a rate of 100 °C / min and held for 10 min. After that, the furnace was allowed to cool naturally to room temperature to obtain a blocky high-entropy carbonitride ceramic with the chemical formula (Ti 0.25 Zr 0.25 Nb 0.25 Ta 0.25 C 0.9 N 0.1 .

[0028] (3) Apply 0.1 mm of CuSnTi solder between the high-entropy carbonitride ceramic and the WC-Co cemented carbide. After drying for 1 h, place it in a brazing furnace. Under vacuum, apply 200 N pressure and heat to 880 °C at 100 °C / min. Hold for 30 min. Then cool naturally to room temperature to obtain the high-entropy carbonitride ceramic composite tool.

[0029] 2. Performance Testing: The high-entropy carbonitride ceramic composite tool has a Vickers hardness of 25 GPa and a fracture toughness of 5.8 MPa·m. 1 / 2 The bending strength is 1262 MPa, and the cutting life of this high-entropy carbonitride ceramic composite tool when used to cut ductile iron is 1633 s.

[0030] Figure 1 This is a schematic diagram of the high-entropy carbonitride ceramic composite tool of the present invention. From... Figure 1 As can be seen from the above, the high-entropy carbonitride ceramic composite tool is made by welding a high-entropy carbonitride ceramic as the tool tip and a WC-Co cemented carbide tool holder with CuSnTi brazing filler metal.

[0031] Example 2

[0032] The difference from Example 1 is that the axial pressure of the discharge plasma sintering in step (2) is 50 MPa.

[0033] The high-entropy carbonitride ceramic composite tool obtained in this embodiment has a Vickers hardness of 27 GPa and a fracture toughness of 4.2 MPa·m. 1 / 2 Its bending strength is 1463MPa and its cutting life is 1643s.

[0034] Example 3

[0035] The difference from Example 1 is that the heat preservation time in step (2) is 20 minutes.

[0036] The high-entropy carbonitride ceramic composite tool obtained in this embodiment has a Vickers hardness of 26.2 GPa and a fracture toughness of 5.2 MPa·m. 1 / 2Its bending strength is 1330MPa and its cutting life is 1595s.

[0037] Example 4

[0038] The difference from Example 1 is that the sintering temperature in step (2) is 930°C.

[0039] The high-entropy carbonitride ceramic composite tool obtained in this embodiment has a Vickers hardness of 26.8 GPa and a fracture toughness of 4.3 MPa·m. 1 / 2 The cutting life is 1621s.

[0040] Example 5

[0041] The difference from Example 1 is that the heat preservation time in step (3) is 1 hour.

[0042] The high-entropy carbonitride ceramic composite tool obtained in this embodiment has a Vickers hardness of 26.5 GPa and a fracture toughness of 4.8 MPa·m. 1 / 2 Its bending strength is 1382 MPa and its cutting life is 1574 s.

[0043] Example 6

[0044] The difference from Example 1 is that the molar ratio in step (1) is 1:1:1:1:1:1:1:1, and the chemical formula of the high-entropy carbonitride ceramic obtained is (Ti 0.25 Zr 0.25 Nb 0.25 Ta 0.25 C 0.5 N 0.5 .

[0045] The high-entropy carbonitride ceramic composite tool obtained in this embodiment has a Vickers hardness of 23.4 GPa and a fracture toughness of 5.8 MPa·m. 1 / 2 Its bending strength is 1283MPa and its cutting life is 1584s.

[0046] In summary, the high-entropy carbonitride ceramic composite cutting tool obtained by this invention has a Vickers hardness of 23–27 GPa and a fracture toughness of 4–6 MPa·m. 1 / 2 The bending strength is 1200-1500 MPa, and the cutting life is 1550 s or more, preferably 1550-1650 s.

[0047] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool, characterized in that, The high-entropy carbonitride ceramic composite cutting tool includes a high-entropy carbonitride ceramic (Ti) as the cutting tip. 0.25 Zr 0.25 Nb 0.25 Ta 0.25 C x N 1-x The ceramic composite tool is made by first mixing TiC, ZrC, NbC, TaC, TiN, ZrN, NbN and TaN, and then sintering them in an argon atmosphere at 1600-1800℃ to obtain a high-entropy carbonitride ceramic; then coating the high-entropy carbonitride ceramic and the WC-Co cemented carbide with CuSnTi brazing filler metal, and then brazing them in a vacuum environment at 880-930℃ under a pressure of 200-300N.

2. The high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool according to claim 1, characterized in that, The particle sizes of TiC, ZrC, NbC, TaC, TiN, ZrN, NbN, and TaN are all 0.8–4 μm, and the purity is greater than 99%.

3. The high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool according to claim 1, characterized in that, The ceramic composite cutting tool has a Vickers hardness of 23–27 GPa and a fracture toughness of 4–6 MPa·m. 1 / 2 Its flexural strength is 1200-1500 MPa.

4. The high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool according to claim 1, characterized in that, The heating rate of the discharge plasma sintering is 50–150 °C / min; the sintering time is 10–20 min; the heating rate of the brazing is 50–200 °C / min; and the brazing time is 0.5–1 h.

5. The high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool according to claim 1, characterized in that, The thickness of the CuSnTi solder is 0.05–0.13 mm.

6. The method for preparing a high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool according to any one of claims 1 to 5, characterized in that, The specific steps include the following: S1. Using anhydrous ethanol as solvent and tungsten carbide as ball milling medium, TiC, ZrC, NbC, TaC, TiN, ZrN, NbN and TaN powders were ball-milled and then dried to obtain mixed powder; S2. The mixed powder is loaded into a graphite mold, and under an argon atmosphere, it is pressurized at 30-50 MPa and subjected to spark plasma sintering at 1600-1800℃ to obtain high-entropy carbonitride ceramics. S3. Coat the high-entropy carbonitride ceramic and WC-Co cemented carbide with CuSnTi brazing filler metal, dry at 80-100℃ for 1-2 hours, then put it into a mold, apply a pressure of 200-300N under vacuum, and braze at 880-930℃ to obtain a high-entropy ceramic composite tool.

7. The method for preparing a high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool according to claim 6, characterized in that, The drying time in step S3 is 1 to 2 hours.

8. The application of the high-hardness and high-strength high-entropy carbonitride ceramic composite cutting tool according to any one of claims 1 to 5 in high-speed cutting of gray cast iron or ductile cast iron.

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