A composite coating cutting tool, its preparation method and application

Abstract

The present invention relates to the technical field of coated cutting tools, and provides a composite coated cutting tool, a preparation method thereof and an application. The multi-layer composite coating not only has good high-temperature oxidation resistance and bonding strength, but also has good anti-adhesion. At the same time, the substrate also has high hot hardness, high toughness and high wear resistance. By exerting the mutual synergistic effect of the multi-layer composite coating and the substrate, the problems of severe oxidation wear, adhesive wear and chipping of the cutting tool during the machining of titanium alloy materials can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coated cutting tools, and particularly relates to a composite coated cutting tool, a preparation method thereof, and an application thereof. Background Art

[0002] Titanium alloys have the characteristics of low density, high strength, strong corrosion resistance, good heat resistance, good biocompatibility, etc., and can be used to manufacture aircraft beams, landing gears, ship components, seawater desalination equipment, compressor blades of aeroengines, casings, artificial joints, dental implants, etc. The processing difficulties of titanium alloys are mainly reflected in the following aspects: 1) The cutting temperature is high. Titanium alloys have poor thermal conductivity, and the heat generated during cutting is difficult to dissipate, resulting in an increase in the cutting temperature, which reduces the hardness of the tool material and exacerbates tool wear. 2) The tool wears quickly. Titanium alloys have a relatively high hardness and are prone to adhesion and diffusion phenomena with the tool material during cutting, thus accelerating tool wear and shortening the service life of the tool. 3) Severe work hardening occurs. During the cutting process of titanium alloys, work hardening is likely to occur on the surface layer, and the surface hardness after hardening can be increased by 1-2 times compared with the original hardness. This not only increases the difficulty of subsequent processing but also easily leads to tool chipping. 4) Large plastic deformation occurs. Titanium alloys have a relatively low elastic modulus and are prone to large elastic and plastic deformations under the action of cutting force, resulting in difficulties in controlling dimensional accuracy and possibly causing vibration, which affects the surface quality of machining. Therefore, the requirements for tool materials in titanium alloy cutting are high hardness and wear resistance, good heat resistance and thermal stability, good anti-adhesion property, 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, a hardness of about 2000 HV, can effectively improve the wear resistance and cutting performance of tools, reduce the friction coefficient between the tool and the titanium alloy, and is commonly used in the machining of titanium alloys 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 combines the characteristics of carbon and nitrogen. Its hardness is higher than that of TiN, reaching 2500 - 3200 HV, has better wear resistance and crater wear resistance, and can withstand higher cutting temperatures and greater cutting forces when cutting titanium alloys. However, the high-temperature oxidation resistance of TiCN is still relatively low. TiAlN (titanium aluminum nitride) coating can form a stable alumina protective film at high temperatures, can maintain good hardness and wear resistance at high temperatures of 900 - 1000 °C, is suitable for high-speed cutting of titanium alloys, and can significantly improve tool life and machining efficiency. However, TiAlN has insufficient anti-adhesion. AlTiN (aluminum titanium nitride) coating has a higher aluminum content than TiAlN coating, its hardness can reach above 3500 HV, and has extremely high wear resistance, heat resistance and chemical stability. When cutting titanium alloys, it can effectively resist high temperatures and chemical reactions, reduce tool wear and the generation of built-up edges, and is especially suitable for dry cutting or high-precision and high-efficiency machining of titanium alloys, but the anti-adhesion of AlTiN is still relatively poor. CrN (chromium nitride) coating has good corrosion resistance and anti-bonding properties, low chemical affinity with titanium alloys, can effectively prevent titanium alloy materials from adhering to the tool surface during cutting, reduce the formation of built-up edges and burrs, thereby improving the machining surface quality, and is commonly used in the machining of titanium alloys with higher requirements for machining surface quality, but its wear resistance is relatively poor. NbN coating has good anti-adhesion when cutting titanium alloys, but NbN coating usually has a higher hardness and larger residual stress, and the coating bonding strength is relatively low, and it is easy to peel off. TiB2 coating has a relatively smooth surface and a low friction coefficient, can reduce the friction between the tool and the workpiece, reduce cutting force and cutting heat, helps to improve the machining surface quality, reduce the generation of built-up edges, and make the cutting process more stable and smooth, but TiB2 coating has poor oxidation resistance. Summary of the Invention

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

[0005] According to the first aspect of the present invention, the present invention provides the following technical solutions:

[0006] A composite coating tool, comprising:

[0007] A substrate and a multi-layer composite coating deposited on the substrate;

[0008] The multi-layer composite coating comprises a bottom layer WN, a first sub-layer TaWN, a second sub-layer AlTaWN, a third sub-layer AlTaN and an outermost layer TaN; the substrate is a WC-based cemented carbide.

[0009] As a preferred embodiment of the composite coating tool according to the present invention, wherein: the fracture toughness K of the substrate IC ≥18.5 MPa·m 1 / 2 and the hardness is 1250 - 1350 HV.

[0010] As a preferred embodiment of the composite coating tool according to the present invention, wherein: the substrate comprises 9.5 - 10.5 wt.% of Co, 1 - 5 wt.% of TaC and 0.5 - 2.5 wt.% of Ru, and the balance is WC; wherein, the average grain size of WC is 1.0 - 1.4 μm.

[0011] As a preferred embodiment of the composite coating tool according to the present invention, wherein: the thickness of the bottom layer WN is 0.1 - 0.2 μm, the thickness of the first sub-layer TaWN is 0.1 - 0.3 μm, the thickness of the second sub-layer AlTaWN is 0.3 - 1.0 μm, the thickness of the third sub-layer 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.

[0012] As a preferred embodiment of the composite coating tool according to the present invention, wherein: the atomic ratio of metal elements Ta and W in the first sub-layer TaWN is (35 - 50):(50 - 65), and the atomic ratio of metal elements to non-metal elements is 0.9 ≤ (Ta + W) / N ≤ 1.1.

[0013] As a preferred embodiment of the composite coating tool according to the present invention, wherein: the atomic ratio of metal elements Al, Ta and W in the second sub-layer 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.

[0014] As a preferred embodiment of the composite coating tool according to the present invention, wherein: the atomic ratio of metal elements Al and Ta in the third sub-layer 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.

[0015] As a preferred embodiment of the composite coating tool according to the present invention, wherein: the multi-layer composite coating is prepared by physical vapor deposition method, preferably, by high power pulsed magnetron sputtering method.

[0016] According to the second aspect of the present invention, the present invention provides the following technical solution:

[0017] A preparation method of the above composite coating tool, comprising the following steps:

[0018] S1. Deposit a bottom layer of WN on the substrate, and its process parameters are: heating temperature is 600 - 650 °C, vacuum degree of the 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 ratio is 10 - 90%, and negative bias voltage is 60 - 100 V;

[0019] S2. Deposit a first sub - coating TaWN on the bottom layer of WN, and its process parameters are: heating temperature is 600 - 650 °C, vacuum degree of the vacuum chamber is 0.2 - 0.6 Pa, Ar flow rate is 200 - 400 sccm, N2 flow rate is 180 - 300 sccm, Ta target power is 6.0 - 12 kW, W target power is 6.0 - 12 kW, pulse frequency is 2000 - 6000 Hz, pulse width is 10 - 200 μs, duty ratio is 10 - 90%, and negative bias voltage is 60 - 80 V;

[0020] S3. Deposit a second sub - coating AlTaWN on the first sub - coating TaWN, and its process parameters are: heating temperature is 600 - 650 °C, vacuum degree of the vacuum chamber is 0.2 - 0.6 Pa, Ar flow rate is 200 - 400 sccm, N2 flow rate is 180 - 300 sccm, Al target power is 1 - 4 kW, Ta target power is 6 - 12 kW, W target power is 6 - 12 kW, pulse frequency is 2000 - 6000 Hz, pulse width is 10 - 200 μs, duty ratio is 10 - 90%, and negative bias voltage is 60 - 80 V;

[0021] S4. Deposit a third sub - coating AlTaN on the second sub - coating AlTaWN, and its process parameters are: heating temperature is 600 - 650 °C, vacuum degree of the vacuum chamber is 0.2 - 0.6 Pa, Ar flow rate is 200 - 400 sccm, N2 flow rate is 180 - 300 sccm, Al target power is 1 - 4 kW, Ta target power is 6 - 12 kW, pulse frequency is 2000 - 6000 Hz, pulse width is 10 - 200 μs, duty ratio is 10 - 90%, and negative bias voltage is 60 - 80 V;

[0022] S5. Deposit the outermost TaN on the third sub-coating AlTaN, and its process parameters are as follows: the heating temperature is 600 - 650 °C, the vacuum degree of the vacuum chamber is 0.2 - 0.6 Pa, the Ar flow rate is 200 - 400 sccm, the N2 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 voltage is 40 - 60 V.

[0023] According to the third aspect of the present invention, the present invention provides the following technical solutions:

[0024] An application of the above composite coating tool in the cutting process of titanium alloy.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention provides a composite coating tool, its preparation method and application. The multi-layer composite coating not only has good high-temperature oxidation resistance and bonding strength, but also has good anti-adhesion. At the same time, the substrate also has high hot hardness, high toughness and high wear resistance. By exerting the mutual synergistic effect of the multi-layer composite coating and the substrate, the problems of serious oxidation wear, adhesive wear and chipping of the tool during the machining of titanium alloy materials can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0028] Figure 1 It is a schematic cross-sectional view of the coating of the present invention.

[0029] The attached 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.

[0030] The realization, functional characteristics and advantages of the object of the present invention will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The technical solutions in the embodiments will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] As Figure 1 shown, the present invention provides a composite coated cutting tool, comprising:

[0033] a substrate 100 and a multi-layer composite coating 200 deposited on the substrate 100;

[0034] The multi-layer composite coating 200 includes a bottom layer 201, a first sub-layer 202, a second sub-layer 203, a third sub-layer 204 and an outermost layer 205; the bottom layer 201 is WN, the first sub-layer 202 is TaWN, the second sub-layer 203 is AlTaWN, the third sub-layer 204 is AlTaN and the outermost layer 205 is TaN; the substrate 100 is a WC-based cemented carbide. The composite coated cutting tool of the present invention has the following characteristics:

[0035] (1) During high-temperature cutting, there is good bonding strength between the substrate and the coating and between the coatings of the present invention. Specifically, the W element in the bottom layer WN can diffuse with the W and Ta elements in the substrate to improve the bonding strength between the substrate and the bottom layer WN; the Ta and W elements in the first sub-layer TaWN can diffuse with the W element in the bottom layer WN to improve the bonding strength between the bottom layer WN and the first sub-layer TaWN; the Al, Ta, and W in the second sub-layer AlTaWN can diffuse with the Ta and W elements in the first sub-layer TaWN to improve the bonding strength between the first sub-layer TaWN and the second sub-layer AlTaWN; the Al and Ta elements in the third sub-layer AlTaN can diffuse with the Al, Ta, and W elements in the second sub-layer AlTaWN to improve the bonding strength between the third sub-layer AlTaN and the second sub-layer AlTaWN; the Ta element in the outermost layer TaN can diffuse with the Al and Ta elements in the third sub-layer AlTaN to improve the bonding strength between the outermost layer TaN and the third sub-layer AlTaN.

[0036] (2) In the present invention, the W element in the multi-layer composite coating can reduce the coating friction coefficient, the Ta element can ensure that the coating has high hardness at high temperature, and the Al element can form a dense alumina protective film at high temperature, making the coating have high oxidation resistance.

[0037] (3) In the present invention, the multi-layer composite coating does not contain Ti element, avoiding interdiffusion with Ti during high-temperature cutting of titanium alloy and causing adhesive wear.

[0038] (4) In the present invention, adding 1-5 wt.% TaC to the cemented carbide substrate can form a solid solution of tungsten carbide and tantalum carbide, improving the hot hardness of the coated tool. When the TaC content is less than 1 wt.%, the content of the solid solution of tungsten carbide and tantalum carbide is low, and the solid solution strengthening effect is poor, unable to effectively improve the hot hardness of the coated tool. When the TaC is too high (such as greater than 5 wt.%), it will reduce the toughness of the cemented carbide coated tool and increase the production cost.

[0039] (5) In the present invention, adding 0.5-2.5 wt.% of Ru to the cemented carbide substrate can enhance the stability of the cobalt phase at high temperatures, inhibit the oxidation and thermal decomposition of the cobalt phase, reduce the degradation of the properties of the cemented carbide caused by the change of the cobalt phase, and enable the alloy to maintain good performance under working conditions such as high-temperature cutting. Ru helps to promote the uniform distribution of the cobalt phase in the cemented carbide, enabling the cobalt phase to better play the role of bonding, binding 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 lower than 0.5 wt.%, it is difficult to inhibit the oxidation and thermal decomposition of the cobalt phase at high temperatures, resulting in the degradation of the properties of the cemented carbide. When the Ru content is relatively high (such as greater than 2.5 wt.%), the production cost is high, and it will also reduce the wettability of the cobalt phase in the cemented carbide to WC, thereby reducing the strength of the cemented carbide tool.

[0040] (6) In the present invention, the fracture toughness K of the substrate IC ≥ 18.5 MPa·m 1 / 2 and the hardness is 1250-1350 HV, ensuring that the composite coated tool has both high strength and high toughness.

[0041] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0042] In the following embodiments, the composite coated cutting 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 cutting tool substrate with a specific shape is prepared through subsequent grinding. Secondly, before preparing the coating, the cutting tool substrate needs to be subjected to edge treatment, surface treatment and ultrasonic cleaning to achieve good edge and surface quality. Then, before formally coating, the surface of the cutting 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 cutting tools, target materials with different compositions are used as coating sources, and physical vapor deposition method, especially high power pulsed magnetron sputtering method, is used to deposit a multi-layer composite coating on the cutting tool substrate. Specifically, in step S1, a bottom layer of WN is deposited on the surface of the cutting tool substrate, in step S2, a first sub-layer of TaWN is deposited on the bottom layer of WN, in step S3, a second sub-layer of AlTaWN is deposited on the surface of the first sub-layer of TaWN, in step S4, a third sub-layer of AlTaN is deposited on the surface of the second sub-layer of AlTaWN, and in step S5, the outermost layer of TaN is deposited on the surface of the third sub-layer of AlTaN.

[0043] For the following control cutting tools, the cutting tool substrates are also pre-treated in the same way first, and then the coating is deposited by physical vapor deposition method.

[0044] Example 1

[0045] A composite coated cutting tool, the cutting tool model is RPHT120408E-MM3 cemented 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, the first sub-layer is 0.2μm thick Ta 0.40 W 0.60 N, the second sub-layer is 0.5μm thick Al 0.25 Ta 0.25 W 0.50 N, the third sub-layer is 1.8μm thick Al 0.60 Ta 0.40 N, and the outermost layer is 1.0μm thick TaN. The Co content in the cemented carbide substrate is 10 wt.%, the Ru content is 1.2 wt.%, the addition amount of TaC is 2wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 20 MPa.m 1 / 2 , and the hardness of the substrate is HV1300.

[0046] Control cutting tool 1-1

[0047] The reference tool 1-1 is a cemented carbide milling insert with the same shape and the same coating as in Example 1. The substrate is prepared by powder metallurgy method. The Co content in the substrate is 10 wt.%, the Ru content is 1.2 wt.%, the addition amount of TaC is 0.5 wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 20 MPa·m 1 / 2 , and the hardness of the substrate is HV1240.

[0048] Reference tool 1-2

[0049] The reference tool 1-2 is a cemented carbide milling insert with the same shape and the same coating as in Example 1. The substrate is prepared by powder metallurgy method. The Co content in the substrate is 10 wt.%, the Ru content is 1.2 wt.%, the addition amount of TaC is 6.5 wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 17 MPa·m 1 / 2 , and the hardness of the substrate is HV1380.

[0050] The above three comparison tools are subjected to a milling comparison test according to the following cutting conditions. The machining material is Ti6Al4V, and the cutting parameters are: 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 is that the flank wear of the tool exceeds 0.3 mm, or the tool has chipping or breakage.

[0051] After the tool of Example 1 is cut for 30 minutes, the wear amount reaches 0.29 mm, and it fails due to normal wear; after the reference tool 1-1 is cut for 25 minutes, the wear amount reaches 0.31 mm; after the reference tool 1-2 is cut for 20 minutes, the cutting edge chips and cannot continue cutting. Under this condition, the tool life of Example 1 is increased by 20% compared with the reference tool 1-1 and increased by 50% compared with the reference tool 1-2.

[0052] Example 2

[0053] A composite coating tool, the tool model is RPHT120408E-MM3 cemented carbide milling insert, and the coating is prepared by the above method. In the multi-layer composite coating, the bottom layer is 0.1 μm thick WN, the first sub-coating is 0.2 μm 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 0.50N, the outermost layer is 1.0 μm thick TaN. The Co content in the cemented carbide substrate is 10.5 wt.%, the Ru content is 1.5 wt.%, the addition amount of TaC is 1 wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 22 MPa·m 1 / 2 , and the hardness of the substrate is HV1330.

[0054] Control tool 2-1

[0055] Control tool 2-1 is a cemented carbide milling insert with the same shape and the same coating as that in Example 2. The substrate is prepared by powder metallurgy method. The Co content in the substrate is 10.5 wt.%, the Ru content is 0.1 wt.%, the addition amount of TaC is 1 wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 16.5 MPa·m 1 / 2 , and the hardness of the substrate is HV1230.

[0056] Control tool 2-2

[0057] Control tool 2-2 is a cemented carbide milling insert with the same shape and the same coating as that in Example 1. The substrate is prepared by powder metallurgy method. The Co content in the substrate is 10.5 wt.%, the Ru content is 3.0 wt.%, the addition amount of TaC is 1 wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 18 MPa·m 1 / 2 , and the hardness of the substrate is HV1370.

[0058] The above three comparison tools are subjected to milling comparison tests according to the following cutting conditions. The machining material is Ti6Al4V, and the cutting parameters are: 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 is that the flank wear of the tool exceeds 0.3 mm, or the tool has chipping or breakage.

[0059] After the tool of this Example 2 is cut for 40 minutes, the wear amount reaches 0.28 mm, and it fails due to normal wear; after the control tool 2-1 is cut for 15 minutes, the wear amount reaches 0.32 mm; after the control tool 2-2 is cut for 30 minutes, the cutting edge chips and cannot continue cutting. Under this condition, the life of the tool of this Example 2 is increased by 167% compared with the control tool 2-1 and increased by 33% compared with the control tool 2-2.

[0060] Example 3

[0061] A composite-coated cutting tool, with the tool model being RPHT120408E-MM3 carbide milling inserts, and the coating is obtained by the above method. In the multi-layer composite coating, the bottom layer is 0.2 μm thick WN, the first sub-layer is 0.3 μm thick Ta 0.40 W 0.60 N, the second sub-layer is 1.0 μm thick Al 0.25 Ta 0.25 W 0.50 N, the third sub-layer is 2.0 μm thick Al 0.60 Ta 0.40 N, and the outermost layer is 0.5 μm thick TaN. The Co content in the carbide substrate is 10 wt.%, the Ru content is 1.2 wt.%, the addition amount of TaC is 2 wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 20 MPa·m 1 / 2 , and the hardness of the substrate is HV1300.

[0062] Control tool 3-1

[0063] Control tool 3-1 is a carbide milling insert with the same shape and the same substrate composition as in Example 3, and the coating is a single-layer Al 0.67 Ti 0.33 N coating with a total thickness of 4.0 μm.

[0064] Control tool 3-2

[0065] Control tool 3-2 is a carbide milling insert with the same shape and the same substrate composition as in Example 3, and the coating is a single-layer TiB2 coating prepared by the conventional high-power pulsed magnetron sputtering technology with a total thickness of 4.0 μm.

[0066] Control tool 3-3

[0067] Control tool 3-3 is a carbide milling insert with the same shape and the same substrate composition as in Example 3, and the coating is a composite coating (substrate + 3 μm Al 0.67 Ti 0.33 N + 1 μm NbN) coating prepared by the conventional high-power pulsed magnetron sputtering technology with a total thickness of 4.0 μm.

[0068] The above four comparison tools are subjected to a milling comparison test according to the following cutting conditions. The machining material is Ti6Al4V, and the cutting parameters are: 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 is that the flank wear of the tool exceeds 0.3 mm, or the tool has chipping or breakage.

[0069] After the tool in Example 3 was cut for 35 minutes, the wear amount reached 0.30 mm, showing normal failure wear. After the control tool 3-1 was cut for 25 minutes, the wear amount reached 0.32 mm, with serious adhesive wear. After the control tool 3-2 was cut for 28 minutes, the cutting edge chipped after adhesive wear and could no longer be cut. After the control tool 3-3 was cut for 30 minutes, the cutting edge chipped after adhesive wear and could no longer be cut. Under this condition, the life of the tool in Example 3 was increased by 40% compared with the control tool 3-1, 25% compared with the control tool 3-2, and 17% compared with the control tool 3-3.

[0070] Example 4

[0071] A composite coating tool, with the tool model being RPHT120408E-MM3 cemented carbide milling insert, and the coating was prepared by the above method. In the multi-layer composite coating, the bottom layer is 0.2 μm thick WN, the first sub-layer is 0.3 μm thick Ta 0.50 W 0.50 N, the second sub-layer is 1.0 μm thick Al 0.30 Ta 0.40 W 0.30 N, the third sub-layer is 2.0 μm thick Al 0.65 Ta 0.35 N, and the outermost layer is 0.5 μm thick TaN. The Co content in the cemented carbide substrate is 10 wt.%, the Ru content is 1.2 wt.%, the TaC addition amount is 2 wt.%, and the rest is WC. The fracture toughness K IC of the substrate is 20 MPa·m 1 / 2 , and the hardness of the substrate is HV1300.

[0072] Control tool 4-1

[0073] Control tool 4-1 is a cemented carbide milling insert with the same shape and the same substrate composition as in Example 4. The difference in the coating from that in Example 4 is that there is no bottom layer WN, and the total thickness is 3.8 μm.

[0074] Control tool 4-2

[0075] Control tool 4-2 is a cemented carbide milling insert with the same shape and the same substrate composition as in Example 4. The difference in the coating from that in Example 4 is that there is no first sub-layer TaWN, and the total thickness is 3.7 μm.

[0076] Control tool 4-3

[0077] Control tool 3 is a cemented carbide milling insert with the same shape and the same substrate composition as in Example 4. The difference in the coating from that in Example 4 is that there is no second sub-layer AlTaWN, and the total thickness is 3.0 μm.

[0078] Control tool 4-4

[0079] The control tool 4-4 is a cemented carbide milling insert having the same shape and the same substrate composition as in Example 4. The difference in the coating from that of Example 4 is that there is no third sub-coating AlTaN, and the total thickness is 2.0 μm.

[0080] The above five kinds of comparison tools are subjected to a milling comparison test according to the following cutting conditions. The machining material is Ti6Al4V, and the cutting parameters are: 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 is that the flank wear of the tool exceeds 0.3 mm, or the tool has chipping or breakage.

[0081] After the tool of Example 4 was cut for 33 minutes, the wear amount reached 0.29 mm, and it failed due to normal wear; after the control tool 4-1 was cut for 20 minutes, the edge coating peeled off to the substrate surface, and the wear amount reached 0.30 mm; after the control tool 4-2 was cut for 26 minutes, the coating between the edges peeled off in layers, and the wear amount reached 0.33 mm. After the control tool 4-3 was cut for 24 minutes, the coating between the edges peeled off in layers, and the wear amount reached 0.31 mm. After the control tool 4-4 was cut for 22 minutes, the coating between the edges peeled off in layers, and the wear amount reached 0.29 mm. Under this condition, the life of the tool of Example 4 is increased by 65% compared with the control tool 4-1, by 27% compared with the control tool 4-2, by 38% compared with the control tool 4-3, and by 50% compared with the control tool 4-4.

[0082] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A composite coating tool, characterized in that, Comprising: A substrate and a multi-layer composite coating deposited on the substrate; The multi-layer composite coating includes a bottom layer WN, a first sub-layer TaWN, a second sub-layer AlTaWN, a third sub-layer AlTaN, and an outermost layer TaN; the substrate is a WC-based cemented carbide; In the first sub-layer TaWN, the atomic ratio of metal elements Ta and W is (35-50):(50-65), and the atomic ratio of metal elements to non-metal elements is 0.9 ≤ (Ta+W) / N ≤ 1.

1.

2. The composite coating tool according to claim 1, wherein Fracture toughness K of the substrate IC ≥18.5 MPa·m 1 / 2 and the hardness is 1250 - 1350 HV.

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

4. The composite coated cutting tool according to claim 1, wherein The thickness of the bottom layer WN is 0.1-0.2 μm, the thickness of the first sub-layer TaWN is 0.1-0.3 μm, the thickness of the second sub-layer AlTaWN is 0.3-1.0 μm, the thickness of the third sub-layer 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.

5. The composite coating tool according to claim 1, characterized in that, In the second sub-layer AlTaWN, the atomic ratio of metal elements Al, Ta, and W 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.

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

1.

7. The composite coating tool according to claim 1, characterized in that, The multi-layer composite coating is prepared by physical vapor deposition.

8. A method for preparing a composite coated cutting tool according to any one of claims 1-7, characterized in that, Including the following steps: S1. Deposit the bottom layer WN on the substrate, and its process parameters are: heating temperature is 600-650 °C, the vacuum degree of the vacuum chamber is 0.2-0.6 Pa, the Ar flow rate is 200-400 sccm, the N2 flow rate is 180-300 sccm, 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 60-100 V; S2. Deposit the first sub-layer TaWN on the bottom layer WN, and its process parameters are: heating temperature is 600-650 °C, the vacuum degree of the vacuum chamber is 0.2-0.6 Pa, the Ar flow rate is 200-400 sccm, the N2 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. Deposit a second sub-coating AlTaWN on the first sub-coating TaWN, and its process parameters are: heating temperature is 600 - 650 °C, vacuum degree of the vacuum chamber is 0.2 - 0.6 Pa, Ar flow rate is 200 - 400 sccm, N2 flow rate is 180 - 300 sccm, Al target power is 1 - 4 kW, Ta target power is 6 - 12 kW, W target power is 6 - 12 kW, pulse frequency is 2000 - 6000 Hz, pulse width is 10 - 200 μs, duty cycle is 10 - 90%, negative bias voltage is 60 - 80 V; S4. Deposit a third sub-coating AlTaN on the second sub-coating AlTaWN, and its process parameters are: heating temperature is 600 - 650 °C, vacuum degree of the vacuum chamber is 0.2 - 0.6 Pa, Ar flow rate is 200 - 400 sccm, N2 flow rate is 180 - 300 sccm, Al target power is 1 - 4 kW, Ta target power is 6 - 12 kW, pulse frequency is 2000 - 6000 Hz, pulse width is 10 - 200 μs, duty cycle is 10 - 90%, negative bias voltage is 60 - 80 V; S5. Deposit the outermost TaN on the third sub-coating AlTaN, and its process parameters are: heating temperature is 600 - 650 °C, vacuum degree of the vacuum chamber is 0.2 - 0.6 Pa, Ar flow rate is 200 - 400 sccm, N2 flow rate is 180 - 300 sccm, Ta target power is 6 - 12 kW, pulse frequency is 2000 - 6000 Hz, pulse width is 10 - 200 μs, duty cycle is 10 - 90%, negative bias voltage is 40 - 60 V.

9. Application of the composite coating tool according to any one of claims 1 - 7 in the cutting process of titanium alloy.

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