Composite coated cutting tool and preparation method and application thereof

Abstract

The invention relates to the technical field of coated cutting tools, and provides a composite coated cutting tool and a preparation method and application thereof, a multi-layer composite coating not only has good high-temperature oxidation resistance and bonding strength, but also has good adhesion resistance, meanwhile, a base body also has high red hardness, high toughness and high wear resistance, and the service life of the composite coated cutting tool is prolonged. By exerting the mutual synergistic effect of the multi-layer composite coating and the base body, the problems of serious oxidative wear, bonding wear and tipping of the cutter during titanium alloy material machining can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coated tool technology, and in particular relates to a composite coated tool and a preparation method and application thereof. Background Art

[0002] Titanium alloys have the characteristics of low density, high strength, strong corrosion resistance, good heat resistance, and good biocompatibility. They can be used to manufacture aircraft beams, landing gear, ship parts, desalination equipment, aircraft engine compressor blades, casings, artificial joints, dental implants, etc. The difficulty of processing titanium alloys is mainly reflected in the following aspects: 1) The cutting temperature is high. The thermal conductivity of titanium alloys is poor. The heat generated during cutting is difficult to dissipate, which leads to an increase in cutting temperature, a decrease in the hardness of the tool material, and an increase in tool wear. 2) The tool wears quickly. The hardness of titanium alloys is relatively high, and it is easy to bond and diffuse with the tool material during the cutting process, thereby accelerating the wear of the tool and shortening the service life of the tool. 3) Severe work hardening. During the cutting process of titanium alloys, the surface layer is prone to work hardening. The hardened surface hardness can be 1-2 times higher than the original hardness. This not only increases the difficulty of subsequent processing, but also easily leads to tool chipping. 4) Large plastic deformation. Titanium alloy has a low elastic modulus, and is prone to large elastic and plastic deformation under the action of cutting force, which makes it difficult to control dimensional accuracy and may also cause vibration, affecting the quality of the processed surface. Therefore, the requirements for tool materials for titanium alloy cutting are high hardness and wear resistance, good heat resistance and thermal stability, good anti-adhesion, and sufficient strength and toughness.

[0003] Physical vapor deposition (PVD) coatings are widely used in the cutting of titanium alloys. TiN (titanium nitride) coating is one of the earliest and most commonly used PVD coatings. It has a golden appearance and a hardness of about 2000HV. It can effectively improve the wear resistance and cutting performance of the tool and reduce the friction coefficient between the tool and titanium alloy. It is often used in titanium alloy processing at general cutting speeds. However, TiN has insufficient oxidation resistance and wear resistance. TiCN (titanium carbonitride) coating is developed on the basis of TiN coating and has the characteristics of both carbon and nitrogen. Its hardness is higher than TiN, reaching 2500-3200HV, and it has better wear resistance and resistance to crater wear. It can withstand higher cutting temperatures and greater cutting forces when cutting titanium alloys. However, TiCN still has low resistance to high-temperature oxidation. TiAlN (titanium aluminum nitride) coating can form a stable aluminum oxide protective film at high temperatures, and can maintain good hardness and wear resistance at high temperatures of 900-1000℃. It is suitable for high-speed cutting of titanium alloys and can significantly improve tool life and processing efficiency. However, TiAlN has insufficient anti-adhesion. The aluminum content of AlTiN (aluminum titanium nitride) coating is higher than that of TiAlN coating, and its hardness can reach more than 3500HV. It has extremely high wear resistance, heat resistance and chemical stability. When cutting titanium alloy, it can effectively resist high temperature and chemical reaction, reduce tool wear and the generation of built-up edge, and is particularly suitable for dry cutting or high-precision and high-efficiency titanium alloy cutting, but AlTiN still has poor anti-adhesion. CrN (chromium nitride) coating has good corrosion resistance and anti-adhesion, and has low chemical affinity with titanium alloy. It can effectively prevent titanium alloy material from adhering to the tool surface during cutting, reduce the formation of built-up edge and burrs, and thus improve the quality of the machined surface. It is often used in titanium alloy cutting with high requirements for machining surface quality, but its wear resistance is poor. NbN coating has good anti-adhesion when cutting titanium alloy, but NbN coating usually has higher hardness and larger residual stress, and the coating bonding strength is low, and it is easy to peel off. TiB 2 The coating surface is relatively smooth and has a low friction coefficient, which can reduce the friction between the tool and the workpiece, reduce the cutting force and cutting heat, help improve the quality of the machined surface, reduce the generation of built-up edge, and make the cutting process smoother and smoother. However, TiB 2 The coating has poor oxidation resistance. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention aims to provide a composite coating tool and a preparation method and application thereof.

[0005] According to the first aspect of the present invention, the present invention provides the following technical solution: A composite coating tool, comprising: A substrate and a multi-layer composite coating deposited on the substrate; The multilayer composite coating comprises a bottom layer of WN, a first sub-coating of TaWN, a second sub-coating of AlTaWN, a third sub-coating of AlTaN and an outermost layer of TaN; and the substrate is a WC-based cemented carbide.

[0006] As a preferred embodiment of the composite coating tool described in the present invention, the fracture toughness K IC ≥18.5MPa·m 1 / 2 , hardness is 1250-1350HV.

[0007] As a preferred embodiment of the composite coated tool described in the present invention, the matrix contains 9.5-10.5 wt.% Co, 1-5 wt.% TaC and 0.5-2.5 wt.% Ru, and the balance is WC; wherein the average grain size of WC is 1.0-1.4 μm.

[0008] As a preferred embodiment of a composite coating tool described in the present invention, the thickness of the bottom layer WN is 0.1-0.2 μm, the thickness of the first sub-coating TaWN is 0.1-0.3 μm, the thickness of the second sub-coating AlTaWN is 0.3-1.0 μm, the thickness of the third sub-coating AlTaN is 1.5-2.0 μm, the thickness of the outermost layer TaN is 0.5-1.5 μm, and the total thickness of the multi-layer composite coating is 2.5-5.0 μm.

[0009] As a preferred embodiment of a composite coating tool described in the present invention, the atomic ratio of metal elements Ta and W in the first sub-coating TaWN is (35-50): (50-65), and the atomic ratio of metal elements and non-metal elements is 0.9≤(Ta+W) / N≤1.1.

[0010] As a preferred embodiment of a composite coated tool described in the present invention, the atomic ratio of metal elements Al, Ta and W in the second sub-coating AlTaWN is (20-30): (15-40): (30-65), and the atomic ratio of metal elements and non-metal elements is 0.9≤(Al+Ta+W) / N≤1.1.

[0011] As a preferred embodiment of a composite coating tool described in the present invention, the atomic ratio of metal elements Al and Ta in the third sub-coating AlTaN is (50-65): (35-50), and the atomic ratio of metal elements and non-metal elements is 0.9≤(Al+Ta) / N≤1.1.

[0012] As a preferred solution of the composite coating tool described in the present invention, the multi-layer composite coating is prepared by a physical vapor deposition method, preferably, by a high-power pulsed magnetron sputtering method.

[0013] According to the second aspect of the present invention, the present invention provides the following technical solution: A method for preparing the composite coating tool comprises the following steps: S1. Deposit the bottom WN on the substrate. The process parameters are: heating temperature 600-650 °C, vacuum degree of the vacuum chamber 0.2-0.6 Pa, Ar flow rate 200-400 sccm, N 2 The flow rate is 180-300 sccm, the target power is 6-12 kW, the pulse frequency is 2000-6000 Hz, the pulse width is 10-200 μs, the duty cycle is 10-90%, and the negative bias voltage is 60-100 V; S2. Deposit the first sub-coating TaWN on the bottom WN, and the process parameters are: heating temperature 600-650 °C, vacuum degree of vacuum chamber 0.2-0.6 Pa, Ar flow rate 200-400 sccm, N 2 The flow rate is 180-300 sccm, the Ta target power is 6.0-12 kW, the W target power is 6.0-12 kW, the pulse frequency is 2000-6000 Hz, the pulse width is 10-200 μs, the duty cycle is 10-90%, and the negative bias voltage is 60-80 V; S3, depositing a second sub-coating AlTaWN on the first sub-coating TaWN, the process parameters of which are: heating temperature of 600-650 °C, vacuum degree of the vacuum chamber of 0.2-0.6 Pa, Ar flow rate of 200-400 sccm, N 2 The flow rate is 180-300 sccm, the Al target power is 1-4 kW, the Ta target power is 6-12 kW, the W target power is 6-12 kW, the pulse frequency is 2000-6000 Hz, the pulse width is 10-200 μs, the duty cycle is 10-90%, and the negative bias voltage is 60-80 V; S4, depositing a third sub-coating AlTaN on the second sub-coating AlTaWN, the process parameters of which are: heating temperature of 600-650 °C, vacuum degree of the vacuum chamber of 0.2-0.6 Pa, Ar flow rate of 200-400 sccm, N 2 The flow rate is 180-300sccm, the Al target power is 1-4 kW, the Ta target power is 6-12 kW, the pulse frequency is 2000-6000 Hz, the pulse width is 10-200μs, the duty cycle is 10-90%, and the negative bias is 60-80 V; S5. Depositing the outermost TaN layer on the third sub-coating AlTaN, the process parameters are: heating temperature of 600-650°C, vacuum degree of the vacuum chamber of 0.2-0.6 Pa, Ar flow rate of 200-400 sccm, N2 The flow rate is 180-300 sccm, the Ta target power is 6-12 kW, the pulse frequency is 2000-6000 Hz, the pulse width is 10-200 μs, the duty cycle is 10-90%, and the negative bias is 40-60 V.

[0014] According to the third aspect of the present invention, the present invention provides the following technical solution: An application of the composite coating tool in cutting titanium alloy.

[0015] The beneficial effects of the present invention are as follows: The present invention provides a composite coating tool and a preparation method and application thereof. The multi-layer composite coating not only has good high-temperature oxidation resistance and bonding strength, but also has good anti-stickiness. At the same time, the substrate also has high red hardness, high toughness and high wear resistance. By giving full play to the synergistic effect of the multi-layer composite coating and the substrate, the problems of severe oxidation wear, bonding wear and chipping of the tool during titanium alloy material processing can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0017] Figure 1 It is a schematic cross-sectional view of the coating of the present invention.

[0018] The reference numerals are as follows: 100 - substrate; 200 - multi-layer composite coating; 201 - bottom layer; 202 - first sub-coating; 203 - second sub-coating; 204 - third sub-coating; 205 - outermost layer.

[0019] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] like Figure 1 As shown, the present invention provides a composite coating tool, comprising: A substrate 100 and a multi-layer composite coating 200 deposited on the substrate 100; The multilayer composite coating 200 comprises a bottom layer 201, a first sub-coating 202, a second sub-coating 203, a third sub-coating 204 and an outermost layer 205; the bottom layer 201 is WN, the first sub-coating 202 is TaWN, the second sub-coating 203 is AlTaWN, the third sub-coating 204 is AlTaN and the outermost layer 205 is TaN; the substrate 100 is a WC-based cemented carbide. The composite coating tool of the present invention has the following characteristics: (1) During high-temperature cutting, the substrate and coating of the present invention and the coatings have good bonding strength. Specifically, the W element in the bottom layer WN can diffuse with the W and Ta elements in the substrate, thereby improving the bonding strength between the substrate and the bottom layer WN; the Ta and W elements in the first sub-coating TaWN can diffuse with the W element in the bottom layer WN, thereby improving the bonding strength between the bottom layer WN and the first sub-coating TaWN; the Al, Ta, and W in the second sub-coating AlTaWN can diffuse with the Ta and W elements in the first sub-coating TaWN, thereby improving the bonding strength between the first sub-coating TaWN and the second sub-coating AlTaWN; the Al and Ta elements in the third sub-coating AlTaN can diffuse with the Al, Ta, and W elements in the second sub-coating AlTaWN, thereby improving the bonding strength between the third sub-coating AlTaN and the second sub-coating AlTaWN; the Ta element in the outermost layer TaN can diffuse with the Al and Ta elements in the third sub-coating AlTaN, thereby improving the bonding strength between the outermost layer TaN and the third sub-coating AlTaN.

[0022] (2) In the present invention, the W element in the multilayer composite coating can reduce the friction coefficient of the coating, the Ta element can ensure that the coating has high hardness at high temperatures, and the Al element can form a dense aluminum oxide protective film at high temperatures, so that the coating has high oxidation resistance.

[0023] (3) In the present invention, the multilayer composite coating does not contain the Ti element, thereby avoiding mutual diffusion with Ti during high-temperature cutting of titanium alloy, thereby preventing adhesion wear.

[0024] (4) In the present invention, 1-5 wt.% TaC is added to the cemented carbide matrix to form a solid solution of tungsten carbide and tantalum carbide, thereby improving the high temperature red hardness of the coated tool. When the TaC content is less than 1 wt.%, the solid solution content of tungsten carbide and tantalum carbide is low, the solid solution strengthening effect is poor, and the high temperature red hardness of the coated tool cannot be effectively improved. When the TaC content is too high (such as greater than 5 wt.%), the toughness of the cemented carbide coated tool will be reduced, and the production cost will be increased.

[0025] (5) In the present invention, adding 0.5-2.5 wt.% Ru to the cemented carbide matrix can enhance the stability of the cobalt phase at high temperature, inhibit the oxidation and thermal decomposition of the cobalt phase, reduce the degradation of the cemented carbide performance caused by the change of the cobalt phase, and enable the alloy to maintain good performance under high-temperature cutting and other working conditions. Ru helps to promote the uniform distribution of the cobalt phase in the cemented carbide, so that the cobalt phase can better play a bonding role and bind the hard phase particles such as tungsten carbide more tightly together, thereby improving the overall strength and toughness of the cemented carbide. When the Ru content is less than 0.5 wt.%, it is difficult to inhibit the oxidation and thermal decomposition of the cobalt phase at high temperature, resulting in a degradation of the cemented carbide performance. When the Ru content is higher (such as greater than 2.5 wt.%), the production cost is higher, and the wettability of the cobalt phase in the cemented carbide to WC is reduced, thereby reducing the strength of the cemented carbide tool.

[0026] (6) In the present invention, the fracture toughness K of the matrix IC ≥18.5 MPa·m 1 / 2 , hardness is 1250-1350HV, ensuring that the composite coated tool has both high strength and high toughness.

[0027] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0028] In the following embodiments, the composite coating tool provided by the present invention is prepared by the following method: first, a cemented carbide blank is made according to the existing powder metallurgy method, and a tool substrate of a specific shape is prepared through a subsequent grinding process. Secondly, before preparing the coating, the tool substrate is subjected to edge treatment, surface treatment and ultrasonic cleaning to achieve good edge and surface quality. Then, before formally coating, the surface of the tool substrate is bombarded with argon ions to further improve the bonding between the coating and the substrate. Finally, according to the requirements of various tools, targets of different compositions are used as coating sources, and a physical vapor deposition method, in particular, a high-power pulsed magnetron sputtering method is used to deposit a multilayer composite coating on the tool substrate, specifically, step S1 is to deposit a bottom layer WN on the surface of the tool substrate, step S2 is to deposit a first sub-coating TaWN on the bottom layer WN, step S3 is to deposit a second sub-coating AlTaWN on the surface of the first sub-coating TaWN, step S4 is to deposit a third sub-coating AlTaN on the surface of the second sub-coating AlTaWN, and step S5 is to deposit the outermost layer TaN on the surface of the third sub-coating AlTaN.

[0029] The following control tools also first undergo the same pretreatment on the tool substrate, and then the coating is deposited using the physical vapor deposition method.

[0030] Example 1 A composite coating tool, the tool model is RPHT120408E-MM3 carbide milling insert, and the coating is prepared by the above method. In the multi-layer composite coating, the bottom layer is 0.1μm thick WN, and the first sub-coating is 0.2μm thick Ta 0.40 W 0.60 N, the second sub-coating is 0.5 μm thick Al 0.25 Ta 0.25 W 0.50 N, the third sub-coating is 1.8 μm thick Al 0.60 Ta 0.40 N, the outermost layer is 1.0μm thick TaN. The Co content in the cemented carbide matrix is ​​10 wt.%, the Ru content is 1.2 wt.%, the TaC addition is 2wt.%, and the rest is WC. The fracture toughness of the matrix is ​​K IC 20 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1300.

[0031] Comparison tool 1-1 The control tool 1-1 is a cemented carbide milling insert having the same shape and the same coating as that of Example 1. The matrix is ​​prepared by powder metallurgy. The Co content in the matrix is ​​10 wt.%, the Ru content is 1.2 wt.%, the TaC addition amount is 0.5 wt.%, and the rest is WC. The fracture toughness K IC 20 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1240.

[0032] Comparison tool 1-2 The control tool 1-2 is a cemented carbide milling insert with the same shape and the same coating as Example 1. The substrate is prepared by powder metallurgy. The Co content in the substrate is 10 wt.%, the Ru content is 1.2 wt.%, the TaC addition amount is 6.5 wt.%, and the rest is WC. The fracture toughness K IC 17 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1380.

[0033] The three types of comparative tools were subjected to milling comparison tests under the following cutting conditions. The machining material was Ti6Al4V, and the cutting parameters were: cutting speed Vc=75 m / min, cutting depth ap=1.2 mm, feed per revolution f=0.4 mm / r, cutting width ae=20 mm, and water cooling. The product life standard was that the tool back face wear exceeded 0.3 mm, or the tool chipped or broke.

[0034] After cutting for 30 minutes, the tool of Example 1 had a wear amount of 0.29 mm, which was normal failure wear; after cutting for 25 minutes, the control tool 1-1 had a wear amount of 0.31 mm; after cutting for 20 minutes, the control tool 1-2 had a chipped edge and could not continue cutting. Under these conditions, the tool life of Example 1 was increased by 20% compared with the control tool 1-1 and by 50% compared with the control tool 1-2.

[0035] Example 2 A composite coating tool, the tool model is RPHT120408E-MM3 carbide milling insert, and the coating is prepared by the above method. In the multi-layer composite coating, the bottom layer is 0.1μm thick WN, and the first sub-coating is 0.2μm thick Ta 0.35 W 0.65 N, the second sub-coating is 0.5 μm thick Al 0.20 Ta 0.15 W 0.65 N, the third sub-coating is 1.8 μm thick Al 0.50 Ta 0.50 N, the outermost layer is 1.0μm thick TaN. The Co content in the cemented carbide matrix is ​​10.5 wt.%, the Ru content is 1.5 wt.%, the TaC addition is 1wt.%, and the rest is WC. The fracture toughness of the matrix is ​​K IC 22 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1330.

[0036] Comparison tool 2-1 The control tool 2-1 is a cemented carbide milling insert with the same shape and the same coating as Example 2. The matrix is ​​prepared by powder metallurgy. The Co content in the matrix is ​​10.5 wt.%, the Ru content is 0.1 wt.%, the TaC addition amount is 1 wt.%, and the rest is WC. The fracture toughness K IC 16.5 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1230.

[0037] Comparison tool 2-2 The control tool 2-2 is a cemented carbide milling insert with the same shape and the same coating as Example 1. The matrix is ​​prepared by powder metallurgy. The Co content in the matrix is ​​10.5 wt.%, the Ru content is 3.0 wt.%, the TaC addition amount is 1 wt.%, and the rest is WC. The fracture toughness K IC 18 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1370.

[0038] The three types of comparative tools were subjected to milling comparison tests under the following cutting conditions. The machining material was Ti6Al4V, and the cutting parameters were: cutting speed Vc=75 m / min, cutting depth ap=1.2 mm, feed per revolution f=0.4 mm / r, cutting width ae=20 mm, and water cooling. The product life standard was that the tool back face wear exceeded 0.3 mm, or the tool chipped or broke.

[0039] After 40 minutes of cutting, the wear of the tool of Example 2 reached 0.28 mm, which was normal failure wear; after 15 minutes of cutting, the wear of the control tool 2-1 reached 0.32 mm; after 30 minutes of cutting, the cutting edge of the control tool 2-2 was broken and could not continue cutting. Under this condition, the life of the tool of Example 2 was increased by 167% compared with the control tool 2-1 and by 33% compared with the control tool 2-2.

[0040] Example 3 A composite coating tool, the tool model is RPHT120408E-MM3 carbide milling insert, and the coating is prepared by the above method. In the multi-layer composite coating, the bottom layer is 0.2μm thick WN, and the first sub-coating is 0.3μm thick Ta 0.40 W 0.60 N, the second sub-coating is 1.0 μm thick Al 0.25 Ta 0.25 W 0.50 N, the third sub-coating is 2.0 μm thick Al 0.60 Ta 0.40 N, the outermost layer is 0.5 μm thick TaN. The Co content in the cemented carbide matrix is ​​10 wt.%, the Ru content is 1.2 wt.%, the TaC addition is 2wt.%, and the rest is WC. The fracture toughness of the matrix is ​​K IC 20 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1300.

[0041] Comparison tool 3-1 The control tool 3-1 is a cemented carbide milling insert with the same shape and the same matrix composition as that of Example 3, and the coating is a single layer of Al prepared by conventional physical vapor deposition. 0.67 Ti 0.33 N coating, total thickness 4.0μm.

[0042] Comparison tool 3-2 The control tool 3-2 is a cemented carbide milling insert with the same shape and matrix composition as Example 3, and the coating is a single layer of TiB prepared by conventional high-power pulsed magnetron sputtering technology. 2 Coating, total thickness 4.0μm.

[0043] Comparison tool 3-3 The control tool 3-3 is a cemented carbide milling insert with the same shape and the same matrix composition as Example 3, and the coating is a composite coating (matrix + 3μm Al 0.67 Ti 0.33 N+1μm NbN) coating with a total thickness of 4.0μm.

[0044] The above four comparison tools were subjected to milling comparison test under the following cutting conditions. The machining material was Ti6Al4V, and the cutting parameters were: cutting speed Vc=75 m / min, cutting depth ap=1.2 mm, feed per revolution f=0.4 mm / r, cutting width ae=20 mm, and water cooling. The product life standard was that the tool back face wear exceeded 0.3 mm, or the tool chipped or broke.

[0045] After cutting for 35 minutes, the tool of Example 3 had a wear amount of 0.30 mm, which was normal failure wear; after cutting for 25 minutes, the control tool 3-1 had a wear amount of 0.32 mm, which was severe adhesive wear; after cutting for 28 minutes, the control tool 3-2 had a chipping edge due to adhesive wear, and could not continue cutting; after cutting for 30 minutes, the control tool 3-3 had a chipping edge due to adhesive wear, and could not continue cutting. Under these conditions, the life of the tool of Example 3 was increased by 40% compared with the control tool 3-1, by 25% compared with the control tool 3-2, and by 17% compared with the control tool 3-3.

[0046] Example 4 A composite coating tool, the tool model is RPHT120408E-MM3 carbide milling insert, and the coating is prepared by the above method. In the multi-layer composite coating, the bottom layer is 0.2μm thick WN, and the first sub-coating is 0.3μm thick Ta 0.50 W 0.50 N, the second sub-coating is 1.0 μm thick Al 0.30 Ta 0.40 W 0.30 N, the third sub-coating is 2.0 μm thick Al 0.65 Ta 0.35 N, the outermost layer is 0.5 μm thick TaN. The Co content in the cemented carbide matrix is ​​10 wt.%, the Ru content is 1.2 wt.%, the TaC addition is 2wt.%, and the rest is WC. The fracture toughness of the matrix is ​​K IC 20 MPa.m 1 / 2 , the hardness of the matrix is ​​HV1300.

[0047] Comparison tool 4-1 The control tool 4-1 is a cemented carbide milling insert having the same shape and the same matrix composition as that of Example 4. The coating differs from that of Example 4 in that there is no bottom layer WN and the total thickness is 3.8 μm.

[0048] Comparison tool 4-2 The control tool 4-2 is a cemented carbide milling insert having the same shape and the same matrix composition as that of Example 4. The coating differs from that of Example 4 in that there is no first sub-coating TaWN and the total thickness is 3.7 μm.

[0049] Comparison tool 4-3 The control tool 3 is a cemented carbide milling insert having the same shape and the same matrix composition as that of the embodiment 4. The coating is different from that of the embodiment 4 in that there is no second sub-coating AlTaWN and the total thickness is 3.0 μm.

[0050] Comparison tool 4-4 The control tool 4-4 is a cemented carbide milling insert having the same shape and the same matrix composition as that of Example 4. The coating is different from that of Example 4 in that there is no third sub-coating AlTaN and the total thickness is 2.0 μm.

[0051] The five comparison tools were subjected to milling comparison tests under the following cutting conditions. The machining material was Ti6Al4V, and the cutting parameters were: cutting speed Vc=75 m / min, cutting depth ap=1.2 mm, feed per revolution f=0.4 mm / r, cutting width ae=20 mm, and water cooling. The product life standard was that the tool back face wear exceeded 0.3 mm, or the tool chipped or broke.

[0052] After cutting for 33 minutes, the tool of Example 4 had a wear amount of 0.29 mm, which was normal failure wear; after cutting for 20 minutes, the edge coating of the control tool 4-1 peeled off to the substrate surface, and the wear amount reached 0.30 mm; after cutting for 26 minutes, the edge coatings of the control tool 4-2 peeled off in layers, and the wear amount reached 0.33 mm. After cutting for 24 minutes, the edge coatings of the control tool 4-3 peeled off in layers, and the wear amount reached 0.31 mm. After cutting for 22 minutes, the edge coatings of the control tool 4-4 peeled off in layers, and the wear amount reached 0.29 mm. Under these conditions, the life of the tool of Example 4 is increased by 65% ​​compared with the control tool 4-1, 27% compared with the control tool 4-2, 38% compared with the control tool 4-3, and 50% compared with the control tool 4-4.

[0053] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A composite coated tool, characterized in that: include: A substrate and a multi-layer composite coating deposited on the substrate; The multilayer composite coating comprises a bottom layer of WN, a first sub-coating of TaWN, a second sub-coating of AlTaWN, a third sub-coating of AlTaN and an outermost layer of TaN; and the substrate is a WC-based cemented carbide.

2. The composite coated tool according to claim 1, characterized in that: Fracture toughness K of matrix IC ≥18.5MPa·m 1 / 2 , hardness is 1250-1350HV.

3. The composite coating tool according to claim 1, characterized in that: The matrix contains 9.5-10.5 wt.% Co, 1-5 wt.% TaC and 0.5-2.5 wt.% Ru, and the balance is WC; wherein the average grain size of WC is 1.0-1.4 μm.

4. The composite coated tool according to claim 1, characterized in that: The thickness of the bottom layer WN is 0.1-0.2μm, the thickness of the first sub-coating TaWN is 0.1-0.3μm, the thickness of the second sub-coating AlTaWN is 0.3-1.0μm, the thickness of the third sub-coating AlTaN is 1.5-2.0μm, the thickness of the outermost layer TaN is 0.5-1.5μm, and the total thickness of the multi-layer composite coating is 2.5-5.0μm.

5. The composite coated tool according to claim 1, characterized in that: The atomic ratio of metal elements Ta and W in the first sub-coating TaWN is (35-50):(50-65), and the atomic ratio of metal elements and non-metal elements is 0.9≤(Ta+W) / N≤1.

1.

6. The composite coated tool according to claim 1, characterized in that: The atomic ratio of metal elements Al, Ta and W in the second sub-coating AlTaWN is (20-30):(15-40):(30-65), and the atomic ratio of metal elements to non-metal elements is 0.9≤(Al+Ta+W) / N≤1.

1.

7. The composite coated tool according to claim 1, characterized in that: The atomic ratio of metal elements Al and Ta in the third sub-coating AlTaN is (50-65):(35-50), and the atomic ratio of metal elements to non-metal elements is 0.9≤(Al+Ta) / N≤1.

1.

8. The composite coated tool according to claim 1, characterized in that: The multilayer composite coating is prepared by physical vapor deposition method.

9. A method for preparing a composite coated tool according to any one of claims 1 to 8, characterized in that: The steps include: S1. Deposit the bottom layer WN on the substrate, and the process parameters are: heating temperature is 600-650 °C, vacuum degree of vacuum chamber is 0.2-0.6 Pa, Ar flow rate is 200-400 sccm, N2 flow rate is 180-300 sccm, W target power is 6-12 kW, pulse frequency is 2000-6000 Hz, pulse width is 10-200 μs, duty cycle is 10-90%, and negative bias voltage is 60-100 V; S2. Depositing the first sub-coating TaWN on the bottom WN, the process parameters are: heating temperature of 600-650 °C, vacuum degree of vacuum chamber of 0.2-0.6 Pa, Ar flow rate of 200-400 sccm, N2 flow rate of 180-300 sccm, Ta target power of 6.0-12 kW, W target power of 6.0-12 kW, pulse frequency of 2000-6000 Hz, pulse width of 10-200 μs, duty cycle of 10-90%, negative bias of 60-80 V; S3, depositing a second sub-coating AlTaWN on the first sub-coating TaWN, with the following process parameters: heating temperature of 600-650°C, vacuum degree of vacuum chamber of 0.2-0.6 Pa, Ar flow rate of 200-400 sccm, N2 flow rate of 180-300 sccm, Al target power of 1-4 kW, Ta target power of 6-12 kW, W target power of 6-12 kW, pulse frequency of 2000-6000 Hz, pulse width of 10-200 μs, duty cycle of 10-90%, negative bias of 60-80 V; S4, depositing a third sub-coating AlTaN on the second sub-coating AlTaWN, with the following process parameters: heating temperature of 600-650°C, vacuum degree of vacuum chamber of 0.2-0.6 Pa, Ar flow rate of 200-400 sccm, N2 flow rate of 180-300 sccm, Al target power of 1-4 kW, Ta target power of 6-12 kW, pulse frequency of 2000-6000 Hz, pulse width of 10-200 μs, duty cycle of 10-90%, and negative bias of 60-80 V; S5. Deposit the outermost layer of TaN on the third sub-coating AlTaN, with the following process parameters: heating temperature of 600-650 °C, vacuum degree of vacuum chamber of 0.2-0.6 Pa, Ar flow rate of 200-400 sccm, N2 flow rate of 180-300 sccm, Ta target power of 6-12 kW, pulse frequency of 2000-6000 Hz, pulse width of 10-200 μs, duty cycle of 10-90%, and negative bias of 40-60 V.

10. Use of the composite coating tool according to any one of claims 1 to 8 in cutting of titanium alloy.

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