Polycrystalline cubic boron nitride coated cutting tool as well as preparation method and application thereof

Abstract

The invention relates to a polycrystalline cubic boron nitride coated cutting tool and a preparation method and application thereof.The polycrystalline cubic boron nitride coated cutting tool comprises a PCBN base body and a first coating formed on the PCBN base body, the PCBN base body is at least provided with a polycrystalline layer, the polycrystalline layer comprises cubic boron nitride, a first binder and a second binder, and the first coating is formed on the PCBN base body. The second binder is selected from a mixture of one or more of aluminum, titanium, cobalt, nickel, tungsten, niobium, tantalum and zirconium, and the ratio of the average particle size of the cubic boron nitride to the average thickness of the first coating is 0.5-2.5. The thermal expansion coefficient of the PCBN polycrystalline layer is matched with the thermal expansion coefficient of the coating by regulating and controlling the formula of the PCBN substrate (the type and proportion of the binder) and the formula of the coating, and the thermal stress between interfaces during cutting is reduced; and by regulating and controlling the thickness of the cubic boron nitride and the coating, the deposition nucleation of the coating is compact, and the hardness of the coating is matched with that of a polycrystalline layer.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cutting tools, and relates to a polycrystalline cubic boron nitride coating tool and a preparation method and application thereof. BACKGROUND

[0002] The microstructure of cubic boron nitride (CBN) is that each boron atom and nitrogen atom are connected by a covalent bond to form a cubic crystal structure similar to diamond; the hardness thereof is only inferior to that of diamond, but the thermal stability and chemical stability thereof are much higher than those of diamond, and the chemical affinity of the cubic boron nitride to iron group elements (iron, cobalt and nickel) is very low, so the cubic boron nitride has a natural advantage in machining steel materials.

[0003] Polycrystalline cubic boron nitride (PCBN) is a polycrystalline composite material formed by sintering CBN particles and a proper amount of a binder (such as titanium, aluminum, cobalt, aluminum nitride and the like) under high temperature and high pressure, which not only inherits the excellent properties of CBN, maintains high hardness, high heat resistance and chemical inertness, but also avoids the problem of brittleness of a single crystal cleavage surface because the PCBN is composed of countless randomly oriented CBN grains, and the performance thereof is consistent in all directions.

[0004] PCBN coating tools are a kind of composite tools combining polycrystalline cubic boron nitride materials and advanced coating technologies, and exhibit significant advantages in the field of cutting machining, and are especially suitable for machining of high-hardness and difficult-to-machine materials. However, the surface energy of PCBN (especially high-CBN-content grades) is low, and the chemical activity thereof is poor, so it is difficult for traditional coating technologies to form a firm chemical bond between the coating and the PCBN, which leads to insufficient bonding force between the coating and the PCBN, and the coating will rapidly peel off under high temperature and high pressure in cutting, which not only causes the protection of the PCBN substrate to fail, but also the peeled hard fragments will intensify the tool wear like abrasives, resulting in early retirement of the tool; meanwhile, there is a difference in the thermal expansion coefficient between the coating material and the PCBN substrate, and the temperature of the tool edge area can reach several hundred degrees or even thousands of degrees in cutting, and is rapidly cooled after stopping cutting, so under the repeated thermal shock, a huge thermal stress will be generated at the interface, which causes microcracks in the coating, and the microcracks are continuously expanded, and finally the coating is peeled off in a large area. PCBN welded tools account for a large proportion in the market, and the PCBN tool bit is fixed to a hard alloy substrate by a welding process, and the melting point of the solder is limited, so if the deposition temperature of the coating is too high, the solder will be softened, and the PCBN tool bit will fall off from the tool shank, so it is necessary to prepare a high-performance coating at a relatively low deposition temperature, which greatly increases the technical difficulty.

[0005] Chinese invention patent CN111910172A discloses a composite coated PCBN cutting tool and its preparation method. The cutting tool includes a PCBN tool substrate and a composite coating coated on the PCBN tool substrate. The composite coating includes an inner A coating and an outer B coating. The A coating includes at least Al prepared by low-pressure chemical vapor deposition. x Ti 1-x C y N 1-y Coating B, comprising at least a Ti layer prepared by physical vapor deposition. 1-a-b Al a Me b N-coating. While this application improves tool life to some extent, it still has some technical shortcomings: improving the bonding performance between PCBN and the coating solely from the coating end leaves room for further improvement in the bonding effect. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide a polycrystalline cubic boron nitride coated cutting tool.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a polycrystalline cubic boron nitride coated cutting tool, comprising a PCBN substrate and a first coating formed on the PCBN substrate, wherein the PCBN substrate has at least a polycrystalline layer, the polycrystalline layer comprising cubic boron nitride, a first binder and a second binder, the second binder being a mixture selected from one or more of aluminum, titanium, cobalt, nickel, tungsten, niobium, tantalum and zirconium, and the ratio of the average particle size of the cubic boron nitride to the average thickness of the first coating being 0.5 to 2.5.

[0008] Optimally, the first binder is a mixture selected from one or more of titanium carbide, titanium nitride, titanium carbide nitride, carbon nitride, niobium nitride, silicon nitride, aluminum oxide, yttrium oxide, and silicon; Optimally, the volume content of cubic boron nitride in the polycrystalline layer is 40-95%, and the D50 is 1.0-2.0 micrometers.

[0009] Ideally, the hardness of the polycrystalline layer is ≥29 GPa, and the hardness of the first coating layer is ≥28 GPa.

[0010] Ideally, the surface roughness Ra of the polycrystalline layer is ≤0.8μm.

[0011] Optimally, the material of the first coating is CrAlN, AlTiN, TiN, AlTiSiYN, TiCN, AlTiSiN, or AlTiVN; optimally, the material of the first coating is Al. a Ti 1-a N, where 0.3≤a≤0.7.

[0012] Optimally, a second coating is also formed on the inner surface of the first coating, the second coating being a mixture of one or more components selected from titanium, chromium and zirconium, and the thickness of the second coating being 50~100 nm.

[0013] Optimally, the PCBN substrate further includes a substrate layer, the polycrystalline layer being formed between the substrate layer and the first coating layer, the substrate layer being a hard alloy layer with a thickness ≥ 0.5 times the thickness of the polycrystalline layer.

[0014] Another object of the present invention is to provide a method for preparing a polycrystalline cubic boron nitride coated cutting tool, comprising the following steps: (S1) The cubic boron nitride, the first adhesive and the second adhesive are mixed in proportion, loaded into a metal cup and compacted, and PCBN sintered body is synthesized under the conditions of temperature 1200℃~1600℃ and pressure 5~8Gpa. (S2) The first coating is deposited on the PCBN sintered body using PVD process at a deposition temperature of 400~600℃ and a deposition bias voltage of -40~-150V.

[0015] Optimally, the feature is that: in step (S2), before deposition, the PCBN sintered body is ground and cut into a PCBN substrate having at least a polycrystalline layer, and then the first coating is deposited on the PCBN substrate; Optimally, in step (S2), the PCBN sintered body is further subjected to heat treatment before deposition, wherein the heat treatment is performed by heating to 600-900°C at a rate of 2-20°C / min, holding at the temperature for 1-10 hours, and then cooling to room temperature in the furnace; Optimally, in step (S2), before depositing the first coating, a second coating is deposited on the PCBN substrate using a PVD process.

[0016] Another object of the present invention is to provide an application of polycrystalline cubic boron nitride coated cutting tools for directly preparing finished cutting tools, or for use in conjunction with cemented carbide cutting tool bodies to prepare finished cutting tools.

[0017] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art: The polycrystalline cubic boron nitride coated cutting tool of the present invention, by adjusting the PCBN substrate (type and proportion of binder) and coating ratio (such as coating component proportion), makes the thermal expansion coefficients of the PCBN substrate (including polycrystalline layer) and the coating match, reducing the thermal stress between the interfaces during cutting; at the same time, by adjusting the CBN particle size and coating thickness, the coating deposition nucleation is dense, and the hardness of the coating and the polycrystalline layer are matched, achieving a good bond between the PCBN substrate and the coating. It not only takes into account the ultra-high hardness and high thermal stability of the PCBN substrate, but also further improves its wear resistance, chemical stability and lubricity through coating technology, which greatly improves the machining efficiency, tool life and machining quality of the cutting tool.

[0018] This invention further enhances the tight bond between the coating and the PCBN polycrystalline layer by controlling the surface state of the polycrystalline layer and introducing a second coating. The coating is less likely to peel off during cutting, which not only takes into account the ultra-high hardness and high thermal stability of the PCBN substrate, but also further improves its wear resistance, chemical stability and lubricity through coating technology, thereby further improving the performance of the cutting tool. Attached Figure Description

[0019] Figure 1 This is a diagram showing the wear on the flank face of the cutting tool in Example 1; Figure 2 This is a diagram showing the wear on the flank face of the cutting tool in Example 2; Figure 3 This is a diagram showing the wear on the flank face of the tool in Comparative Example 1. Figure 4 This is a diagram showing the wear on the flank face of the tool in Comparative Example 2; Figure 5 This is a comparison diagram of the tool's flank wear. Figure 6 This is a schematic diagram illustrating an application of the polycrystalline cubic boron nitride coated cutting tool of the present invention; Among them, 1 is a polycrystalline cubic boron nitride coated cutting tool; 11 is a PCBN substrate; 111 is a polycrystalline layer; 112 is a substrate layer; 12 is a first coating; 13 is a second coating; and 2 is a cemented carbide cutting tool body. Detailed Implementation

[0020] The polycrystalline cubic boron nitride coated cutting tool 1 of the present invention, such as Figure 6As shown, it includes a PCBN substrate 11 and a first coating 12 formed on the PCBN substrate 11 (the formation method includes, but is not limited to, deposition processes, such as PVD). The PCBN substrate 11 has at least a polycrystalline layer 111, which includes cubic boron nitride, a first binder, and a second binder. The second binder is a mixture selected from one or more of aluminum, titanium, cobalt, nickel, tungsten, niobium, tantalum, and zirconium. The ratio of the average particle size of the cubic boron nitride to the average thickness of the first coating 12 is 0.5 to 2.5 (the ratio can be any value within this range, such as 0.5, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5, etc.). By adjusting the PCBN substrate 11 (type and proportion of binder) and coating ratio (such as coating component proportion), the thermal expansion coefficients of the PCBN substrate 11 (including polycrystalline layer 111) and the coating are matched, reducing thermal stress between the interfaces during cutting. At the same time, by adjusting the CBN particle size and coating thickness, the coating deposition nucleation is made dense, and the hardness of the coating and polycrystalline layer 111 are matched, achieving a good bond between the PCBN substrate 11 and the coating. This not only takes into account the ultra-high hardness and high thermal stability of the PCBN substrate 11, but also further improves its wear resistance, chemical stability and lubricity through coating technology, greatly improving the machining efficiency, tool life and machining quality of the tool.

[0021] The first binder is a mixture selected from one or more of titanium carbide, titanium nitride, titanium carbide nitride, carbon nitride, niobium nitride, silicon nitride, aluminum oxide, yttrium oxide, and silicon. The volume content of cubic boron nitride in the polycrystalline layer 111 is 40-95% (the volume content of cubic boron nitride can be any value within the aforementioned range, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, etc., the same below; preferably 60-80%), and D50 is 1.0-2.0 micrometers; the remainder is the volume percentage of the binder, which can be the sum of the volume percentages of the first and second binders, or other binders (such as a third binder or / and a fourth binder, etc.) can be added as needed. In one embodiment of the present invention, the volume ratio of cubic boron nitride to binder (including a first binder and a second binder) is 56:44. For example, the first binder can be TiN and TiCN, and the second binder can be Al and W, with a volume ratio of TiN:TiCN:Al:W = 7:7:3:4. The surface roughness Ra of the polycrystalline layer 111 is ≤0.8μm. The hardness of the polycrystalline layer 111 is ≥29Gpa, and the hardness of the first coating 12 is ≥28Gpa. The material of the first coating 12 is CrAlN, AlTiN, TiN, AlTiSiYN, TiCN, AlTiSiN, or AlTiVN; preferably Al. a Ti 1-aN, where 0.3 ≤ a ≤ 0.7. The thickness of the polycrystalline layer 111 is 0.7~0.9 mm. As mentioned above, the ratio of the average particle size of cubic boron nitride to the average thickness of the first coating 12 is 0.5~2.5. Under the premise of meeting this ratio requirement, the average particle size of cubic boron nitride is preferably 1.5~5 μm, which can further ensure that the generated coating is smooth, has few surface defects, and is not easy to peel off.

[0022] In one embodiment of the present invention, cubic boron nitride is preferably composed of four different micro-powders of different coarseness (<1.0μm, 1.0~1.5μm, 1.5~3.0μm, >3μm), and the volume ratio of <1.0μm:1.0~1.5μm:1.5~3.0μm:3μm is 2:3:2.5:2.5. This provides extremely high wear resistance and thermal conductivity, while making the structure of the polycrystalline layer 111 more compact, thereby improving the strength and toughness of the material and preventing crack propagation.

[0023] A second coating 13 is also formed on the inner surface of the first coating 12. The second coating 13 is a mixture selected from one or more of titanium, chromium, and zirconium, and its thickness is 50-100 nm. Thus, by further controlling the surface state and formulation of the polycrystalline layer 111 and introducing the second coating 13, the tight bond between the coating and the PCBN polycrystalline layer 111 is further improved, making the coating less prone to peeling during cutting. The purpose of adding the second coating 13 is to further improve the adhesion between the coating and the substrate. This is because adding a thin layer of the second coating 13 can improve the conductivity of the substrate, allowing it to become an effective "electrode" during the subsequent deposition of the first coating 12 in the coating furnace chamber, thereby stably bearing the negative bias voltage. This negative bias voltage will form a strong electric field on the substrate surface, which strongly attracts and accelerates positive ions in the plasma through Coulomb force, causing them to bombard the substrate surface with high energy. Simultaneously, it covers surface defects, forming a fresh, clean, and flat surface, unifying the surface energy, and ensuring that the subsequent coating can be deposited on the entire substrate surface with a uniform nucleation rate and growth rate, thereby obtaining a coating with consistent thickness and performance.

[0024] The PCBN substrate 11 also includes a substrate layer 112, and a polycrystalline layer 111 is formed between the substrate layer 112 and the first coating layer 12. The substrate layer 112 is a hard alloy layer, and its thickness is ≥ 0.5 times the thickness of the polycrystalline layer 111 (the thickness of the substrate layer 112 can be adjusted according to actual needs, such as being set to 1.4 mm; it can be made of different materials according to actual needs, such as having a cobalt content of 10% and a WC grain size of 0.8~1.2 μm).

[0025] The preparation method of the above-mentioned polycrystalline cubic boron nitride coated tool 1 includes the following steps: (S1) Cubic boron nitride, a first adhesive and a second adhesive are mixed in proportion, loaded into a metal cup and compacted, and a PCBN sintered body (i.e., polycrystalline layer 111) is synthesized under the conditions of temperature 1200℃~1600℃ and pressure 5~8Gpa; (S2) A first coating 12 is deposited on the PCBN sintered body using PVD process at a deposition temperature of 400~600℃ and a deposition bias voltage of -40~-150V.

[0026] In step (S2), before deposition, the PCBN sintered body is ground and cut into a PCBN substrate 11 having at least a polycrystalline layer 111, and then a first coating 12 is deposited on the PCBN substrate 11. In step (S2), the PCBN sintered body is also subjected to heat treatment before deposition. The heat treatment involves heating to 600-900°C at a rate of 2-20°C / min, holding at that temperature for 1-10 hours, and then cooling to room temperature in the furnace. (In one embodiment of the invention, after removing the surface metal scale, the sintered body is placed in a vacuum furnace for heat treatment: heated to 870°C at a rate of 6°C / min, held at that temperature for 6 hours, and then cooled to room temperature in the furnace. In another embodiment of the invention, it is preferable to heat treat the finely ground sintered body in a vacuum furnace: heated to 600°C at a rate of 10°C / min, then heated to 900°C at a rate of 3°C / min, held at that temperature for 8 hours, and then cooled to room temperature in the furnace.) In step (S2), before depositing the first coating 12, a second coating 13 is deposited on the PCBN substrate 11 using a PVD process. In step (S1), a hard alloy is placed in a metal cup to give the PCBN substrate 11 a substrate layer 112.

[0027] In one embodiment of the present invention, step (S1) employs a segmented heating method, with the first stage heating to 1200°C and the second stage heating to 1420°C, while maintaining a constant pressure of 5.4 GPa. In another embodiment of the present invention, step (S1) employs a segmented pressurization method, with the first stage pressurizing to 4.6 GPa and holding for 15 seconds, and the second stage pressurizing to 5.6 GPa, while simultaneously raising the temperature to 1480°C. In another embodiment of the present invention, the synthesized PCBN sintered body preferably undergoes end-face grinding and centerless grinding to remove the surface metal scale, followed by fine grinding with a ceramic grinding wheel for 12 hours to achieve a surface roughness Ra of 0.2 μm.

[0028] The present invention also provides an application of the above-mentioned polycrystalline cubic boron nitride coated cutting tool 1, which is used to prepare a finished cutting tool in conjunction with a cemented carbide cutting tool body 2; specifically, the above-mentioned PCBN substrate 11 is welded to a specific cemented carbide cutting tool body 2 by vacuum welding, and the finished PCBN cutting tool (i.e., finished cutting tool) is made by peripheral grinding, edge treatment and other processes.

[0029] In one embodiment of the present invention, the aforementioned PCBN substrate 11 is cleaned and dried and then placed in a coating furnace. The temperature of the furnace is raised to 560°C and argon gas is introduced to perform ion etching treatment on the tool surface for 40 minutes. Then, a pure titanium coating of about 50 nm is deposited on the tool (deposition temperature is 480°C, deposition bias voltage is -100V), followed by the deposition of an AlTiN coating of about 2.8 μm (deposition temperature is 520°C, deposition bias voltage is -70V), thus producing a finished PCBN tool.

[0030] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings. Example 1

[0031] This embodiment provides a polycrystalline cubic boron nitride coated cutting tool, its preparation method, and its application, as detailed below: (S1) Mix 80% (volume content, the same below) of cubic boron nitride (average particle size of cubic boron nitride is 5μm), 13% of titanium carbide nitride (first binder) and 7% of aluminum (second binder), and pack them together with cemented carbide (to form a substrate layer) into a metal cup, compact them, and sinter them at 1520℃ and 5.1GPa to form a PCBN sintered body; (S2) The PCBN sintered body is ground and cut to form a PCBN substrate (isosceles triangle with a vertex angle of 83° and two sides of 3.5 mm. The PCBN substrate has a substrate layer and a polycrystalline layer). In order to simplify the subsequent preparation of finished tools, the PCBN substrate is first welded to the C-type cemented carbide tool body by vacuum welding, and the CNGA120408 finished tool is made by peripheral grinding and other processes. (S3) Then the finished CNGA120408 blade is placed in a coating furnace to deposit an AlTiN coating of about 2.5 μm thickness (deposition temperature 520℃, deposition bias -70V, Al: 63%).

[0032] The cubic boron nitride coated tool prepared in this embodiment was subjected to cutting tests. The workpiece material was ductile iron QT600-3. Under the condition of a cutting stroke of 9000m, the maximum wear on the flank face of the tool in this embodiment was 110μm (e.g., Figure 1 (As shown). Example 2

[0033] This embodiment provides a polycrystalline cubic boron nitride coated cutting tool, its preparation method, and its application. The difference between this embodiment and Embodiment 1 is that in step (S1), 60% (volume content, the same below) of cubic boron nitride (average particle size of cubic boron nitride is 1.5 μm), 29% titanium carbide nitride (first binder), 9% aluminum (second binder), and 2% tungsten (second binder) are mixed evenly, while the other steps are the same.

[0034] The cubic boron nitride coated tool prepared in this embodiment was subjected to cutting tests. The workpiece material was ductile iron QT600-3. Under the condition of a cutting stroke of 9000m, the maximum wear on the flank face of the tool in this embodiment was 90μm (e.g., Figure 2 (As shown).

[0035] Comparative Example 1 This embodiment provides a polycrystalline cubic boron nitride coated cutting tool, its preparation method and application, which is basically the same as that in Example 1, except that: in step (S1), the average particle size of cubic boron nitride is 8μm.

[0036] The cubic boron nitride coated tool prepared in this embodiment was subjected to cutting tests. The workpiece material was ductile iron QT600-3. Under the condition of a cutting stroke of 6750m, the maximum wear on the flank face of the tool in this embodiment was 310μm (e.g., Figure 3 (As shown).

[0037] Comparative Example 2 This example provides a method for preparing a cutting tool, which is basically the same as that in Example 1, except that step (S3) is not performed.

[0038] The cutting tool prepared in this example was subjected to a cutting test. The workpiece material was ductile iron QT600-3. Under the condition of a cutting stroke of 9000m, the maximum wear on the flank face of the tool in this example was 541μm (e.g., Figure 4 (As shown).

[0039] Comparative Example 3 This example provides a method for preparing a cutting tool, which is basically the same as that in Example 2, except that step (S3) is not performed.

[0040] The cutting tool prepared in this example was subjected to a cutting test. The workpiece material was ductile iron QT600-3. Under the condition of a cutting stroke of 9000m, the maximum wear on the flank face of the tool in this example was 281μm (e.g., Figure 5 (As shown).

[0041] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A polycrystalline cubic boron nitride coated cutting tool, comprising a PCBN substrate and a first coating formed on the PCBN substrate, characterized in that: The PCBN substrate has at least a polycrystalline layer, which comprises cubic boron nitride, a first binder, and a second binder. The second binder is a mixture selected from one or more of aluminum, titanium, cobalt, nickel, tungsten, niobium, tantalum, and zirconium. The ratio of the average particle size of the cubic boron nitride to the average thickness of the first coating is 0.5 to 2.

5.

2. The polycrystalline cubic boron nitride coated cutting tool according to claim 1, characterized in that: The first binder is a mixture selected from one or more of titanium carbide, titanium nitride, titanium carbide nitride, carbon nitride, niobium nitride, silicon nitride, aluminum oxide, yttrium oxide, and silicon; Ideally, the volume content of cubic boron nitride in the polycrystalline layer is 40-95%, and the D50 is 1.0-2.0 micrometers.

3. The polycrystalline cubic boron nitride coated cutting tool according to claim 1, characterized in that: The hardness of the polycrystalline layer is ≥29 GPa, and the hardness of the first coating layer is ≥28 GPa.

4. The polycrystalline cubic boron nitride coated cutting tool according to claim 1, characterized in that: The surface roughness Ra of the polycrystalline layer is ≤0.8μm.

5. The polycrystalline cubic boron nitride coated cutting tool according to claim 1, characterized in that: The material of the first coating is CrAlN, AlTiN, TiN, AlTiSiYN, TiCN, AlTiSiN or AlTiVN; Ideally, the material of the first coating is Al. a Ti 1-a N, where 0.3≤a≤0.

7.

6. The polycrystalline cubic boron nitride coated cutting tool according to claim 1, characterized in that: A second coating is also formed on the inner surface of the first coating. The second coating is a mixture of one or more of titanium, chromium and zirconium, and the thickness of the second coating is 50~100 nm.

7. The polycrystalline cubic boron nitride coated cutting tool according to claim 1, characterized in that: The PCBN substrate further includes a substrate layer, and the polycrystalline layer is formed between the substrate layer and the first coating layer. The substrate layer is a hard alloy layer with a thickness ≥ 0.5 times the thickness of the polycrystalline layer.

8. The method for preparing the polycrystalline cubic boron nitride coated cutting tool according to any one of claims 1 to 7, characterized in that, Includes the following steps: (S1) The cubic boron nitride, the first adhesive and the second adhesive are mixed in proportion, loaded into a metal cup and compacted, and PCBN sintered body is synthesized under the conditions of temperature 1200℃~1600℃ and pressure 5~8Gpa. (S2) The first coating is deposited on the PCBN sintered body using PVD process at a deposition temperature of 400~600℃ and a deposition bias voltage of -40~-150V.

9. The method for preparing the polycrystalline cubic boron nitride coated cutting tool according to claim 8, characterized in that: In step (S2), the PCBN sintered body is ground and cut into a PCBN substrate with at least a polycrystalline layer before deposition, and then the first coating is deposited on the PCBN substrate. Optimally, in step (S2), the PCBN sintered body is further subjected to heat treatment before deposition. The heat treatment involves heating to 600-900°C at a rate of 2-20°C / min, holding at that temperature for 1-10 hours, and then cooling to room temperature in the furnace. Ideally, in step (S2), before depositing the first coating, a second coating is also deposited on the PCBN substrate using a PVD process.

10. The application of the polycrystalline cubic boron nitride coated cutting tool according to any one of claims 1 to 7, characterized in that: Used to directly manufacture finished knives, or used in conjunction with cemented carbide knife bodies to manufacture finished knives.

Images