Coated cutting tool

Abstract

This invention relates to a coated cutting tool, comprising a substrate body and a coating, wherein the substrate is a cemented carbide, and the coating comprises: a first metal nitride layer comprising microcrystals with a NaCl structure and microcrystals with grain boundary phases between the NaCl structure microcrystals; and / or a first metal nitride layer comprising microcrystals with a NaCl structure including different domain types having different elemental compositions, and wherein a 10 to 500 nm thick Al layer is present beneath the first metal nitride layer. 1‑v‑y‑ z M v Si y X z N layer, 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, M is one or more metallic elements from groups 4, 5, and 6 of the periodic table, X is one or more of C, B, and O, Al 1‑v‑y‑ z M v Si y X z The N-layer has a wurtzite crystal structure.

Description

[0001] This invention relates to a coated cutting tool comprising a cemented carbide substrate and a wear-resistant coating deposited on the substrate. The invention also relates to a method for manufacturing the coated cutting tool. Background Technology

[0002] Cutting tools for metal cutting typically consist of a base material made of cemented carbide with a wear-resistant coating deposited on it. The cemented carbide contains a hard component of tungsten carbide (WC) within a metallic binder phase, typically cobalt.

[0003] The wear-resistant coating is a metal nitride deposited using a commonly used PVD (physical vapor deposition) process. Metal nitride coatings can be a single layer or multiple layers with different elemental compositions. Examples of metal nitrides include (Ti,Al)N, (Al,Cr)N, (Ti,Al,Cr)N, and (Ti,Al,Si)N. The most commonly used metal nitride is (Ti,Al)N.

[0004] The general shape and specific geometry of cutting tools depend on the intended metal cutting operation. Examples of cutting tools include milling inserts, turning inserts, drills, and end mills.

[0005] Different wear processes on a cutting tool eventually degrade its performance, necessitating replacement. Therefore, when manufacturing coated cutting tools for metal cutting, the primary objective is to ensure the tool can be used for as long as possible; that is, the tool life should be as long as possible.

[0006] In addition to the coating itself exhibiting wear resistance during metal cutting operations, good adhesion between the substrate and the wear-resistant coating is crucial. The primary consequence of poor adhesion is coating flaking, which leads to increased tool wear and reduced tool life. Poor adhesion also typically limits the usable coating thickness. This is particularly relevant for PVD coatings, which often exhibit compressive stress in freshly deposited coatings. The thicker the coating, the higher the adhesion required to prevent flaking.

[0007] When depositing metal nitride layers via PVD processes, the temperature during the process is typically maintained at a moderate level. Freshly deposited metal nitrides generally exhibit good adhesion to cemented carbide substrates. Heat treatment of certain deposited metal nitride layers can improve mechanical properties, particularly the toughness of the layer. Heat treatment can result in the introduction of thin grain boundary phases with a hexagonal crystalline structure between cubic crystallites within the cubic metal nitride layer. This can improve the toughness of the metal nitride layer. Furthermore, for some metal nitrides, heat treatment can lead to the separation of different phases, for example, through Spinodal decomposition, which may also improve toughness.

[0008] Spinora decomposition is a mechanism that allows a single phase to separate into two domains without nucleation. The resulting two domains have the same crystal structure but different elemental compositions. Spinora decomposition can occur when a metastable phase is exposed to elevated temperatures. Many aluminum nitrides containing NaCl microcrystals are known to undergo Spinora decomposition upon heating. This Spinora decomposition results in the formation of two domains with different elemental compositions.

[0009] However, during relatively long heat treatments at high temperatures, such as those described above for improving the mechanical properties of the metal nitride layer, there is a risk that binder metal (typically cobalt) diffuses from the cemented carbide substrate into the deposited metal nitride. This can negatively impact the adhesion between the substrate and the metal nitride layer, resulting in a shortened tool life for coated cutting tools.

[0010] Purpose of the invention

[0011] One object of the present invention is to provide a coated cutting tool exhibiting significant interdiffusion resistance of the binder metal between the cemented carbide substrate and the coating. Another object of the present invention is to provide a coated cutting tool having a cemented carbide substrate and a coating comprising a metal nitride layer, exhibiting good adhesion to the substrate even after harsh heat treatment. Coated cutting tools generally also preferably exhibit high wear resistance, showing high flank wear resistance in metal machining operations such as milling, turning, and drilling. Finally, an object of the present invention is to provide a method for manufacturing a coated cutting tool. Summary of the Invention

[0012] This invention relates to a coated cutting tool, comprising a substrate body and a coating, wherein the substrate is a cemented carbide and the coating comprises a first metal nitride layer of 0.2 to 25 µm thickness, consisting of one or more metal elements from groups 4, 5, and 6 of the periodic table and Al, or one or more metal elements from groups 4, 5, and 6 of the periodic table and Al and Si, wherein the first metal nitride layer comprises...

[0013] (i) Microcrystals of NaCl structure and microcrystals of grain boundary phase between microcrystals of NaCl structure, the microcrystals of grain boundary phase having wurtzite crystal structure, the area fraction of wurtzite crystal structure in the first metal nitride layer (7) being greater than 0.5% but less than 10% as measured in 2D cross-sectional images of SEM or TEM. and / or (ii) Microcrystals containing different domain types of NaCl structure, with different elemental compositions among the domain types. The different elemental compositions of the domain types result in repeating peaks in the intensity line distribution analysis of the 2D cross-sectional images of the microcrystals by SEM or TEM. There is a peak spacing between two consecutive peaks, and the average peak spacing is 5 to 30 nm according to the intensity line distribution analysis of the microcrystals. Furthermore, it contains an Al layer 10 to 500 nm thick located beneath the first metal nitride layer. 1-v-y-z M v Si y X z N layers, 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, where Al 1-v-y-z M v Si y X z The distance between the N layer and the substrate surface is 0 to 500 nm, M is one or more metallic elements from groups 4, 5, and 6 of the periodic table, X is one or more of C, B, and O, and Al 1-v-y-z M v Si y X z The N-layer has a wurtzite crystal structure.

[0014] The present invention also relates to a method for manufacturing a coated cutting tool, the method comprising the following steps: - Provides a cemented carbide substrate body - Install the substrate body in the PVD chamber. - A coated cutting tool is formed by depositing a coating onto a substrate using a PVD method. The coating comprises: an Al layer with a thickness of 10 to 500 nm. 1-v-y-z M v Si y X z N layer, 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, Al 1-v-y-z M v Si y X z The N-layer has a wurtzite crystal structure; and a first metal nitride layer of 0.2 to 25 µm thickness consisting of one or more metals from Groups 4, 5, and 6 of the periodic table, and Al, or one or more metals from Groups 4, 5, and 6 of the periodic table, and Al and Si. 1-v-y-z M v Si y X z The N layer is located below the first metal nitride layer, where Al 1-v-y-z M v Si y X zThe distance between the N layer and the substrate surface is 0 to 500 nm. - Heat-treat the coated cutting tool at 700 to 1000°C for 10 to 300 minutes in an anti-oxidation atmosphere or in a vacuum.

[0015] The coated cutting tool is suitably heat-treated at 800 to 950°C, preferably 825 to 900°C. This temperature is adjusted to provide a sufficient level of improved mechanical properties, such as toughness, within the first metal nitride layer, while minimizing the diffusion of the binder metal into the layer. Higher temperatures result in greater diffusion of the binder metal.

[0016] The coated cutting tool is suitable for heat treatment for a period of 30 to 150 minutes, preferably 45 to 100 minutes.

[0017] The atmosphere for preventing oxidation is preferably an inert gas atmosphere, such as one or more of Ar, Xe or Kr.

[0018] The PVD method used can be any known PVD method, such as cathodic arc deposition, ion plating, reactive sputtering, or HIPIMS.

[0019] In one embodiment, the present invention relates to a coated cutting tool comprising a substrate body and a coating, the substrate being a cemented carbide and the coating comprising a first metal nitride layer of 0.2 to 25 µm thickness containing one or more metal elements from groups 4, 5, and 6 of the periodic table and Al, or one or more metal elements from groups 4, 5, and 6 of the periodic table and Al and Si, the first metal nitride layer comprising microcrystals of NaCl structure and microcrystals of grain boundary phase between the microcrystals of NaCl structure, the microcrystals of the grain boundary phase having a wurtzite crystal structure, the area fraction of the wurtzite crystal structure in the first metal nitride layer (7) being greater than 0.5% but less than 10% as measured by 2D cross-sectional images of SEM or TEM, and wherein a 10 to 500 nm thick layer of Al is present below the first metal nitride layer. 1-v-y-z M v Si y X z N layers, 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, where Al 1-v-y-z M v Si y X z The distance between the N layer and the substrate surface is 0 to 500 nm, M is one or more metallic elements from groups 4, 5, and 6 of the periodic table, X is one or more of C, B, and O, and Al 1-v-y- z Mv Si y X z The N-layer has a wurtzite crystal structure.

[0020] In one embodiment, the present invention relates to a coated cutting tool comprising a substrate body and a coating, wherein the substrate is a cemented carbide and the coating comprises a first metal nitride layer of 0.2 to 25 µm thickness containing one or more metal elements from groups 4, 5, and 6 of the periodic table and Al, or one or more metal elements from groups 4, 5, and 6 of the periodic table and Al and Si, wherein the first metal nitride layer comprises microcrystals comprising NaCl structures of different domain types having different elemental compositions from each other, the different elemental compositions of the domain types causing repetitive peaks in the intensity line distribution analysis of the 2D cross-sectional images of the microcrystals by SEM or TEM, with a peak spacing between two consecutive peaks, and the average peak spacing is 5 to 30 nm according to the intensity line distribution analysis of the microcrystals, and wherein there is an Al layer of 10 to 500 nm thickness located below the first metal nitride layer. 1-v-y-z M v Si y X z N layers, 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, where Al 1-v-y-z M v Si y X z The distance between the N layer and the substrate surface is 0 to 500 nm, M is one or more metallic elements from groups 4, 5, and 6 of the periodic table, X is one or more of C, B, and O, and Al 1-v-y-z M v Si y X z The N-layer has a wurtzite crystal structure.

[0021] In one embodiment, the present invention relates to a coated cutting tool comprising a substrate body and a coating, wherein the substrate is a cemented carbide and the coating comprises a first metal nitride layer of 0.2 to 25 µm thickness consisting of one or more metal elements from groups 4, 5, and 6 of the periodic table and Al, or one or more metal elements from groups 4, 5, and 6 of the periodic table and Al and Si, wherein the first metal nitride layer comprises

[0022] (i) Microcrystals of NaCl structure and microcrystals of grain boundary phase between microcrystals of NaCl structure, the microcrystals of grain boundary phase having wurtzite crystal structure, the area fraction of wurtzite crystal structure in the first metal nitride layer (7) being greater than 0.5% but less than 10% as measured in 2D cross-sectional images of SEM or TEM. and (ii) The NaCl-structured crystallites contain different domain types with distinct elemental compositions. These different domain compositions result in repetitive peaks in the intensity line distribution analysis of the 2D cross-sectional images of the crystallites using SEM or TEM. There is a peak spacing between two consecutive peaks, and based on the intensity line distribution analysis of the crystallites, the average peak spacing ranges from 5 to 30 nm. Furthermore, it contains an Al layer 10 to 500 nm thick located beneath the first metal nitride layer. 1-v-y-z M v Si y X z N layers, 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, where Al 1-v-y-z M v Si y X z The distance between the N layer and the substrate surface is 0 to 500 nm, M is one or more metallic elements from groups 4, 5, and 6 of the periodic table, X is one or more of C, B, and O, and Al 1-v-y-z M v Si y X z The N-layer has a wurtzite crystal structure.

[0023] This paper discloses two independent features related to the microstructure of the first metal nitride layer. The first microstructure feature involves the presence of wurtzite-structured grain boundary phases between NaCl-structured crystallites. The second microstructure feature involves the presence of NaCl-structured crystallites containing different domain types with distinct elemental compositions. Only one of these microstructure features may be present in the first metal nitride layer. Alternatively, both microstructure features may be present. The elemental composition of the first metal nitride plays a decisive role in this. Both microstructure features contribute to improvements in the mechanical properties of the first metal nitride layer, such as increased toughness.

[0024] Al 1-v-y-z M v Si y X z The N-layer has a wurtzite crystal structure, which in this paper refers to Al. 1-v-y-z M v Si y X z The N-layer contains little or no cubic structure, or any other crystal structure. This is defined in this paper as follows: in TEM analysis, or a combination of SEM and TEM analysis, in a 2D cross-sectional image, Al... 1-v-y-z M v Si y X zThe area fraction of microcrystals with a wurtzite structure in the N-layer is at least 90%, preferably at least 95%.

[0025] Surprisingly, Al with a wurtzite structure was discovered. 1-v-y-z M v Si y X z The thin N-layer acts as an effective barrier layer to prevent the binder metal from diffusing upwards from the cemented carbide substrate into the metal nitride coating. This binder metal diffusion can occur during prolonged heating of the coated cutting tool. This enables the provision of metal nitride-coated cemented carbides where the metal nitride exhibits high toughness, while the coating exhibits excellent adhesion to the substrate. Even w-Al 1-v-y- z M v Si y X z The N layer is very thin, w-Al 1-v-y-z M v Si y X z N also has the effect of preventing the diffusion of metal in the binder.

[0026] Suitablely, Al 1-v-y-z M v Si y X z The thickness of the N layer is 20 to 300 nm, or 30 to 150 nm, or 40 to 75 nm.

[0027] Suitablely, Al 1-v-y-z M v Si y X z The distance between the N layer and the surface of the substrate is 0 to 200 nm, preferably 0 to 100 nm, and most preferably 0 to 50 nm.

[0028] In one implementation, Al 1-v-y-z M v Si y X z The N layer is located directly beneath the first metal nitride layer.

[0029] In a preferred embodiment, Al 1-v-y-z M v Si y X z The N layer is located on the surface of the substrate bulk. However, if a thin layer of, for example, cubic metal nitride (i.e., without a wurtzite structure) is placed on the surface of the substrate bulk and Al... 1-v-y-z M v Si y X zThis invention also applies between N layers. Therefore, Al 1-v-y-z M v Si y X z The N layer is defined in this paper as being located below the first metal nitride layer, wherein Al 1-v-y-z M v Si y X z The distance between the N layer and the substrate surface is 0 to 500 nm, preferably 0 to 200 nm, more preferably 0 to 100 nm, and most preferably 0 to 50 nm.

[0030] Therefore, in one embodiment, there exists Al located on the surface of the substrate body. 1-v-y-z M v Si y X z The cubic second metal nitride layer beneath the N layer is at most 500 nm thick, or at most 200 nm thick, or at most 100 nm thick, or at most 50 nm thick. This cubic second metal nitride is suitably a metal nitride of one or more metals from Groups 4, 5, and 6 of the periodic table, optionally combined with Al and / or Si.

[0031] A "cubic" metal nitride layer in this paper refers to a metal nitride layer with a large amount of cubic structure, i.e., a metal nitride layer containing little or no hexagonal structure or any other crystal structure. This is defined in this paper as follows: in TEM analysis, or a combination of SEM and TEM analysis, the area fraction of cubic microcrystals in a 2D cross-sectional image of the "cubic" metal nitride layer is at least 90%.

[0032] Therefore, for example, during heat treatment, a certain amount of hexagonal structure (wurtzite structure) may form in some metal nitrides, mainly existing as a grain boundary phase. Thus, even if a small amount of hexagonal structure is present as defined herein, the metal nitride layer is still defined as a cubic metal nitride layer.

[0033] In a preferred embodiment, Al 1-v-y-z M v Si y X z The N layer is located on the surface of the substrate and directly beneath the first metal nitride layer. This refers to Al. 1-v-y-z M v Si y X z The distance between the N layer and the surface of the substrate is 0 nm.

[0034] In Al 1-v-y-z M v Si y Xz In the N layer, it is suitable for 0 < v ≤ 0.70, or 0.05 ≤ v ≤ 0.70, or 0.10 ≤ v ≤ 0.70.

[0035] In Al 1-v-y-z M v Si y X z In the N layer, it is suitable for 0 ≤ y ≤ 0.15, or 0 ≤ y ≤ 0.10.

[0036] In Al 1-v-y-z M v Si y X z In the N layer, it is suitable for 0 ≤ z ≤ 0.05, preferably 0 ≤ z ≤ 0.02.

[0037] In one embodiment, in Al 1-v-y-z M v Si y X z In the N layer, 0 < v ≤ 0.70, 0 ≤ y ≤ 0.15, 0 ≤ z ≤ 0.05.

[0038] In Al 1-v-y-z M v Si y X z In the N layer, a small amount of inert gases such as Ne, Ar, Kr, and Xe may additionally be present because inert gases may be used in the PVD deposition process. Suitably, the amount of inert gas present may be at most about 5 atomic %, or at most about 3 atomic %, or at most 1 atomic % of the whole (Al 1-v-y- z M v Si y X z N + inert gas).

[0039] What is important in the present invention is that the Al 1-v-y-z M v Si y X z N layer has a wurtzite crystal structure. More than one metal element M can be selected from the range of metal elements disclosed herein, as long as the formed Al 1-v-y-z M v Si y X z N layer has a wurtzite crystal structure.

[0040] In Al 1-v-y-z M v Si y X z In the N layer, M is suitably one or more metal elements in Groups 4, 5, and 6 of the Periodic Table.

[0041] In Al 1-v-y-z M v Si y X z in the N layer, M is suitably one or more of Ti, Zr, Hf, V, Nb, Ta, Cr, preferably one or more of Ti, Zr and Cr.

[0042] Generally, a relatively high Al content is required in Al 1-v-y-z M v Si y X z N to form a wurtzite crystal structure. However, different metals M have different promoting effects on the formation of the wurtzite crystal structure. For example, compared with Ti, Zr promotes the formation of wurtzite at a lower Al content. The general formula Al 1-v-y-z M v Si y X z the following specific embodiments within N reflect this.

[0043] In one embodiment, Al 1-v-y-z M v Si y X z the N layer is Al 1-a-z Ti a X z N, 0 < a ≤ 0.30, 0 ≤ z ≤ 0.10, X is one or more of C, B and O. Suitable is 0.05 ≤ a ≤ 0.27, or 0.05 ≤ a ≤ 0.22. Suitable is 0 ≤ z ≤ 0.05, preferably 0 ≤ z ≤ 0.02.

[0044] In one embodiment, Al 1-v-y-z M v Si y X z the N layer is Al 1-b-z Zr b X z N, 0 < b ≤ 0.70, 0 ≤ z ≤ 0.10, X is one or more of C, B and O. Suitable is 0.05 ≤ b ≤ 0.70, or 0.05 ≤ b ≤ 0.65. Suitable is 0 ≤ z ≤ 0.05, preferably 0 ≤ z ≤ 0.02.

[0045] In one embodiment, Al 1-v-y-z M v Si y X z the N layer is Al 1-c-d-z Ti c Zr d X zN, 0 < c + d ≤ 0.70, 0 ≤ z ≤ 0.10, X is one or more of C, B, and O. Suitable for 0.05 ≤ c + d ≤ 0.70. Suitable for 0.05 ≤ c ≤ 0.45, or 0.10 ≤ c ≤ 0.40. Suitable for 0.05 ≤ d ≤ 0.40, or 0.10 ≤ d ≤ 0.35. Suitable for 0 ≤ z ≤ 0.05, preferably 0 ≤ z ≤ 0.02.

[0046] In one embodiment, Al 1-v-y-z M v Si y X z The N layer is Al 1-e-z Cr e X z N, 0 < e ≤ 0.25, 0 ≤ z ≤ 0.10, X is one or more of C, B, and O. Suitable for 0.05 ≤ e ≤ 0.20. Suitable for 0 ≤ z ≤ 0.05, preferably 0 ≤ z ≤ 0.02.

[0047] In one embodiment, Al 1-v-y-z M v Si y X z The N layer is Al 1-f-g-z Ti f Si g X z N, 0 < f ≤ 0.50, 0 < g ≤ 0.20, 0 ≤ z ≤ 0.10, X is one or more of C, B, and O. Suitable for 0.05 ≤ f ≤ 0.40. Suitable for 0.05 ≤ g ≤ 0.15. Suitable for 0 ≤ z ≤ 0.05, preferably 0 ≤ z ≤ 0.02.

[0048] There is an embodiment in which the first metal nitride layer contains microcrystals of a grain boundary phase between microcrystals of the NaCl structure, and the grain boundary phase has a wurtzite crystal structure. It is considered that the presence of the grain boundary phase between the microcrystals of the NaCl structure in the first metal nitride layer makes it more difficult for cracks to propagate along the grain boundaries of the microcrystals of the NaCl structure. This means that the toughness of the first metal nitride layer is improved.

[0049] The grain boundary phase does not need to be present in all the grain boundaries between the microcrystals of the NaCl structure. The grain boundary phase seen in the 2D cross-sectional images of SEM or TEM is separated grains or fragments between the microcrystals of the NaCl structure.

[0050] Suitably, the average thickness of the grain boundary phase is in the range of at most 30 nm, preferably at most 15 nm. The grain boundary phase is easily seen in the 2D cross-sectional images of SEM or TEM. The average thickness of the grain boundary phase can be determined by image analysis.

[0051] The area fraction of wurtzite crystal structure in the first metal nitride layer, as measured in 2D cross-sectional images by SEM or TEM, is preferably greater than 1% but less than 8%, and more preferably greater than 1.5% but less than 6%.

[0052] The following implementation is available, wherein the NaCl structured microcrystals contain different domain types, the domain types have different elemental compositions, the different elemental compositions of the domain types cause repeated peaks in the intensity line distribution analysis of the 2D cross-sectional images of the microcrystals by SEM or TEM, there is a peak spacing between the two consecutive peaks, and according to the intensity line distribution analysis of the microcrystals, the average peak spacing is 5 to 30 nm, preferably 10 to 22 nm.

[0053] In 2D cross-sectional images of NaCl-structured microcrystals using SEM or TEM, domains with different elemental compositions will appear as domains of varying sizes. See an example. Figure 9 The image shows a 2D cross-sectional SEM image of the first metal nitride layer according to an embodiment of the present invention. A granular substructure is visible, comprising two domain groups with different brightness levels, which originates from the different elemental compositions of the domains.

[0054] The term "first metal nitride layer" as used herein includes both an embodiment where the middle layer is a single layer and another embodiment where the middle layer is a multilayer with alternating sublayers. When more than one metal element is present in the first metal nitride layer, a multilayer embodiment exists. A multilayer with alternating sublayers can be a multilayer composed of different sublayers of one or more elements, each with a thickness of 1 to 200 nm, 1 to 100 nm, or 1 to 50 nm.

[0055] When the first metal nitride layer is multilayered, the elemental composition characteristics of the first metal nitride layer as defined in this paper are considered in terms of the overall average elemental composition of the entire multilayer.

[0056] In one embodiment, the fracture toughness of the first metal nitride layer is 4.5 to 7.5 MPa. m 0.5 or 5.0 to 7.0 MPa m 0.5 or 5.5 to 6.5 MPa m 0.5 .

[0057] In one embodiment, the first metal nitride is suitably one or more of Ti, Cr, Zr, Ta, Nb and V, and a metal nitride of Al, or one or more of Ti, Cr, Zr, Ta, Nb and V, and a metal nitride of Al and Si.

[0058] In one embodiment, the first metal nitride is suitably a metal nitride of one or more of Ti, Cr, and Zr and Al, or a metal nitride of one or more of Ti, Cr, and Zr and Al and Si.

[0059] In one embodiment, the first metal nitride layer belongs to (Ti,Al)N, (Ti,Al,Si)N, (Ti,Al,Cr)N, (Ti,Al,Cr,Si)N, and (Cr,Al)N.

[0060] In one embodiment, the content of Al in the first metal nitride is 20 - 70 atomic % of all metal elements, preferably 30 - 65 atomic %.

[0061] In one embodiment, the first metal nitride layer belongs to (Ti,Al)N, (Ti,Al,Si)N, (Ti,Al,Cr)N, and (Ti,Al,Cr,Si)N.

[0062] In one embodiment, the first metal nitride layer is Ti 1-h-i Al h Me i N layer, 0.30 ≤ h ≤ 0.75, or 0.40 ≤ h ≤ 0.70, and 0 < i ≤ 0.10, or 0 < i ≤ 0.05, where Me belongs to one or more metal elements in Groups 4, 5, and 6 of the Periodic Table of the Elements and Si. In one embodiment, Me is one or more of V, Cr, Zr, Ta, Nb, and Si.

[0063] In one embodiment, the first metal nitride layer is a (Ti,Al)N layer.

[0064] In one embodiment, the first metal nitride layer is Ti 1-j Al j N layer, 0.30 ≤ j ≤ 0.75, or 0.40 ≤ j ≤ 0.70.

[0065] The first metal nitride is suitably a cubic metal nitride as defined herein.

[0066] The thickness of the first metal nitride layer is suitably 0.5 to 15 µm, preferably 1 to 10 µm, most preferably 3 to 10 µm.

[0067] The first metal nitride layer is suitably deposited by a PVD method.

[0068] The cubic second metal nitride layer is suitably deposited by a PVD method.

[0069] Al 1-v-y-z Mv Si y X z The N-layer is suitable for deposition via PVD.

[0070] In one embodiment, the Al of the coated cutting tool 1-v-y-z M v Si y X z The N layer is located on the surface of the substrate body and directly below the first metal nitride layer, Al 1-v-y-z M v Si y X z Layer N is Al 1-a-z Ti a X z N and X are one or more of C, B and O, 0.05≤a≤0.22, 0≤z≤0.02, the first metal nitride layer is a (Ti,Al)N layer, and the thickness of the first metal nitride layer is 0.5 to 15 µm.

[0071] In one embodiment, the thickness of the entire coating on the coated cutting tool is suitably from 0.5 to 26 µm, preferably from 2 to 16 µm, and most preferably from 4 to 11 µm. The ideal thickness depends on, for example, the metal cutting application.

[0072] The substrate is a cemented carbide comprising WC and a binder metal. The binder metal is preferably Co. The substrate is preferably a WC-Co based cemented carbide containing 5 to 15% by weight Co. The substrate may optionally also contain cubic carbides or carbonitrides commonly known in the art.

[0073] In one implementation, from Al 1-v-y-z M v Si y X z Between a distance of 0.2 µm from the interface between the N layer and the first metal nitride layer and a distance of 1.2 µm from the interface; or, if the thickness of the first metal nitride layer is less than 1.2 µm, the content of binder metal (preferably Co) in the first metal nitride layer from the distance of 0.2 µm to the uppermost surface of the first metal nitride layer is ≤0.2 atomic%, suitable ≤0.1 atomic%, preferably ≤0.05 atomic%, and most preferably ≤0.02 atomic%.

[0074] The cutting tool is preferably an indexable cutting insert, such as a milling insert, a turning insert, or a drilling insert. Alternatively, the cutting tool is preferably a drill or an end mill.

[0075] A cutting tool suitably includes a rake face and a flank face, with a cutting edge in between.

[0076] method

[0077] Elemental composition: The relationships between metal elements in any nitride layers disclosed herein can be determined by combining energy-dispersive X-ray (EDX) analysis with SEM or TEM.

[0078] wurtzite area fraction in the first metal nitride layer: The content of wurtzite crystals within the first metal nitride layer is determined by the area fraction in a 2D cross-sectional image obtained from SEM or TEM. For an area fraction less than 1%, TEM is preferred. The area of ​​the SEM or TEM image is suitably 2 to 4 µm. 2 In this invention, images of approximately 2 µm × 1.5 µm were used for measurement. Image analysis software was suitably used. In this invention, software called "Gwyddion" was used, which is a standard open-source software for analyzing scanning probe microscopy images. When using an Everhart Thornley detector, wurtzite structures are visible as a darker phase in the image. Standard image analysis was performed. This included background leveling to obtain more uniform contrast. The image was then segmented into two pixel intervals based on a grayscale threshold. One interval was for the wurtzite precipitates (the darker portion in the grayscale image), and the other interval was for all other portions. The pixel size in the image depends on the resolution and magnification of the input image. Acquisition parameters need to be selected to adequately resolve nanoscale precipitates. The ratio of the pixel area of ​​the precipitate interval to the total pixel area of ​​the image was then determined to obtain the wurtzite area fraction.

[0079] Average peak spacing in intensity line distribution analysis of NaCl structured microcrystals in the first metal nitride layer: To obtain a measure of the degree of grain transformation (i.e. decomposition into independent domains with different chemical compositions) within the NaCl structure microcrystals in the first nitride layer, the characteristic length of the obtained chemical fluctuations was analyzed.

[0080] As the basis of this analysis, planar cross-sectional images of at least five different crystallites were acquired using a scanning electron microscope (SEM). A transmission electron microscope (TEM) can also be used. Acquisition conditions, magnification, and image resolution were selected to ensure that any chemical fluctuations in the range of at least five nanometers could be resolved. Before any image analysis, all micrographs were cropped to include only the internal domains of a single crystallite. For each image, a virtual array containing at least four parallel and equidistant lines was constructed and superimposed on the image, with a minimum distance of 20 nm between adjacent lines. For each superimposed line, the corresponding gray-scale intensity line distribution was extracted from the image. For each intensity distribution, the local gray-scale maximum corresponding to one of the domains was identified, i.e., the location of all intensity peaks. The length of each line was chosen to contain at least 15 peaks. The average spacing between adjacent peaks across all intensity distributions was calculated as a measure of the characteristic chemical fluctuation distance.

[0081] After obtaining the average peak spacing of the first linear array, the above steps are repeated for another N linear arrays, each rotating relative to the previous linear array by a fixed angular increment. An angular increment is chosen to capture a total angular range of 180° across ≥30 linear arrays with equal angular increments. This is to obtain the average value for all possible planar directions. The average peak spacing specified in this paper always refers to the average peak spacing across all directions and images.

[0082] Therefore, in the 2D cross-sectional images of the microcrystals by SEM or TEM, the average peak spacing is determined by the distribution of at least 30 intensity lines within the microcrystal, and images from at least five microcrystals are used in the measurement.

[0083] Fracture toughness: To quantify the fracture toughness of the studied coating, a micropillar splitting technique developed by Sebastiani et al. [1, 2, and 4] was employed. In this test method, a sharp indenter tip is positioned at the center of the top surface of a micrometer-sized micropillar of the sample material. The micropillar applies a load to the indenter, with the force continuously increasing until the micropillar fractures, i.e., splits. The critical stress intensity factor at which cracks initiate from the indenter contact point is defined as the splitting fracture toughness. The critical splitting force can be obtained through the following formula. Export: K c = (E / H) P / R 3 / 2 (1) in R represents the proportionality coefficient, which depends on the elastoplastic properties of the tested material (the ratio of Young's modulus E to hardness H), while R represents the radius of the micropillar. The above formula is based on the analytical model of a semi-elliptical surface crack and has been verified by finite element modeling of the bonded zone (CZ-FEM) [2].

[0084] These micropillars were micromachined from the coating of interest using focused ion beam (FIB) milling. A single milling strategy was employed, using a concentric ring pattern with progressively decreasing diameter to minimize the taper of the micropillars. Thus, the FIB probe current was progressively reduced from 15 nA (initial roughing) to a final polishing current of 300 pA. All tested micropillars had a diameter of 7 μm and an aspect ratio of approximately 1.3 (the height-to-diameter ratio is >1 according to the requirements of the micropillar splitting technique [2]). Before any FIB milling, the surface of the sample to be structured was carefully polished using a colloidal silica suspension with a particle size of 40 nm (Struers OPS 0.04 μm). This step was used to remove any roughness present on the surface of the deposited coating. The top layer of coating no larger than 100 nm was removed by this process.

[0085] After this surface treatment, the micropillars are always located at a distance of about 120 μm from the cutting edge, close to the "tip radius" of the substrate.

[0086] The micropillars were loaded using a Fischer Picodenter HM500 nanoindenter (Helmut Fischer GmbH, Sindelfingen, Germany) with a diamond indenter with a three-sided pyramidal angular shape (normal surface angle of 35.26°). The experiment was conducted in a load-controlled manner with a constant loading rate of 1 mN / s. At least 12 tests were performed for each coating and sample condition, taking into account the inherent bias of fracture experiments (20 tests in most cases). The experiment verified that the accuracy of the sample stage and tip positioning was within 10% of the radius of the micropillar used to avoid the bias of the measurement results [3]. In order to calculate the fracture toughness according to Equation (1), coating-specific values ​​were derived from data published by Ghidelli et al. in reference [4]. Coefficient. Measurements can be performed by examining the cross-section of a coated tool or by carefully removing the top layer via mechanical polishing or focused ion beam processing.

[0087] [1] M. Sebastiani, K.E. Johanns, E.G. Herbert, F. Carassiti, G.M.Pharr, A novel Pillar indentation splitting test for measuring fracturetoughness of thin ceramic coatings, Philos. Mag. 95 (2015) 1928–1944.https: / / doi.org / 10.1080 / 14786435.2014.913110.

[0088] [2] M. Sebastiani, K.E. Johanns, E.G. Herbert, G.M. Pharr,Measurement of fracture toughness by nanoindentation methods: Recent advancesand future challenges, Curr. Opin. Solid State Mater. Sci. 19 (2015) 324–333.https: / / doi.org / 10.1016 / j.cossms.2015.04.003.

[0089] [3] C.M. Lauener, L. Petho, M. Chen, Y. Xiao, J. Michler, J.M.Wheeler, Fracture of Silicon: Influence of rate, positioning accuracy, FIBmachining, and elevated temperatures on toughness measured by pillarindentation splitting, Mater. Des. 142 (2018) 340–349. https: / / doi.org / 10.1016 / j.matdes.2018.01.015.

[0090] [4] M. Ghidelli, M. Sebastiani, KE Johanns, GM Pharr, Effects ofindenter angle on micro‐scale fracture toughness measurement by pillarsplitting, J. Am. Ceram. Soc. 100 (2017) 5731–5738. https: / / doi.org / 10.1111 / jace.15093.

[0091] Thickness and adhesion were tested by grinding the calotte cap: The layer thickness was determined by grinding with a spherical cap. A dome-shaped groove was ground using a 30 mm diameter steel ball, and the ring diameter was further measured to calculate the layer thickness. Layer thickness was measured on the rake face of the cutting tool at a distance of 2000 µm from the tool tip, and on the flank face at the center. A spherical cap was ground into the coating and substrate materials by rotating a 30 mm steel ball wetted with a drop of 1 µm water-based single-crystal diamond suspension (Buehler MetaDi blue) at 400 rpm via a drive shaft. The grinding process was stopped when the diameter of the spherical cap in the substrate material reached approximately 300 μm. The appearance of the coating after grinding with the spherical cap was also evaluated. The amount of peeling at the spherical cap grinding point was assessed. The degree of peeling reflects the adhesion between the coating and the substrate.

[0092] Qualitative elemental mapping and quantitative linear distribution of elements, low-kV EDX analysis

[0093] To quantify the interdiffusion of elements between the substrate and the coating, EDX measurements were performed on cross-sectional specimens of the sample. The sample blade was cut in half edge-to-center and embedded in graphite-filled thermosetting resin. The resulting microslices were ground and polished with a diamond suspension with progressively smaller particle sizes (down to 1 µm), followed by a chemical mechanical polishing step using an alkaline colloidal silica suspension (Struers OPS) with an average particle size of 40 nm.

[0094] EDX measurements were performed on a ZeissSupra 40P FEG-SEM using an Oxford Instruments Ultim Max 170 SDD detector. A low electron beam accelerating voltage of 5 kV was used to maximize spatial resolution and reliably separate the coating and substrate portions. The aperture size was chosen to be 60 µm. Measurements were performed at a working distance of 8 mm, and the EDX processing time was set to 3. The channel resolution was set to a maximum of 5 eV.

[0095] Data were acquired at a distance of 120 µm from the cutting edge. Each analysis was set to perform EDX mapping within a field of view of 7.6 µm by 5.3 µm, with a scan resolution of 1024 by 768 points. Each measurement lasted 65 minutes. Continuous drift correction was performed during the measurement using digital image correlation. Attached Figure Description

[0096] Figure 1 A schematic diagram showing one embodiment of a cutting tool as an indexable insert is provided.

[0097] Figure 2 A schematic cross-sectional view of one embodiment of the coated cutting tool of the present invention is shown, illustrating the substrate and the coating.

[0098] Figure 3 The image shows the ball cap of the comparative coated cutting tool, sample 12 (HT850℃) (comparative), after grinding.

[0099] Figure 4 An image showing the grinding of the ball cap cover of sample 3 (HT850°C) (invention), an embodiment of the coated cutting tool of the present invention, is presented.

[0100] Figure 5 An elemental mapping image is shown for comparison of coated cutting tools. Sample 12 (HT850℃) (Comparison).

[0101] Figure 6 An elemental mapping image showing one embodiment of the coated cutting tool of the present invention. Sample 3 (HT850°C) (Invention).

[0102] Figure 7 The linear distribution of elements is shown for comparative coated cutting tools. Sample 12 (HT850℃) (Comparative).

[0103] Figure 8 The linear distribution of elements is shown for one embodiment of the coated cutting tool of the present invention. Sample 3 (HT850°C) (Invention).

[0104] Figure 9 A 2D cross-sectional SEM image of the first metal nitride layer is shown in one embodiment of the present invention. Sample 13 (HT950°C) (Invention).

[0105] Figure 10 This image shows a 2D cross-sectional SEM image of a NaCl-structured microcrystal within a first metal nitride layer according to one embodiment of the present invention. Sample 13 (HT950°C) (Invention).

[0106] Figure 11The intensity line distribution on a SEM2D cross-sectional image of NaCl-structured microcrystals in the first metal nitride layer is shown in one embodiment of the present invention. Sample 13 (HT950℃) (Invention).

[0107] Figure 12 A STEM image showing a cross-section of one embodiment of the coated cutting tool of the present invention, showing the innermost part of the substrate and the coating. Detailed Implementation

[0108] Figure 1 A schematic diagram of one embodiment of a cutting tool (1) having a rake face (2), a flank face (3), and a cutting edge (4) is shown. In this embodiment, the cutting tool (1) is an indexable insert.

[0109] Figure 2 A schematic cross-sectional view of one embodiment of the coated cutting tool (1) of the present invention, having a substrate body (5) and a coating (6). The coating (6) comprises an innermost thin metal nitride layer (8) having a wurtzite structure and a first metal nitride layer (7).

[0110] Figure 9 A 2D cross-sectional SEM image of the first metal nitride layer (7) in one embodiment of the present invention is shown. Grain boundary phase (10) is visible.

[0111] Figure 10 A 2D cross-sectional SEM image of a NaCl-structured microcrystal within a first metal nitride layer (7) according to one embodiment of the present invention is shown. Within the NaCl-structured microcrystal, two domains of different depths, a first domain (11) and a second domain (12), are visible. This represents domains with different elemental compositions.

[0112] Figure 12 A STEM image of a cross section of one embodiment of the coated cutting tool (1) of the present invention, having a substrate body (5), an innermost wurtzite-structured thin metal nitride layer (8), and a first cubic metal nitride layer (7).

[0113] Example

[0114] Example 1: Preparation of "Samples 1-3 (freshly deposited)" and "Samples 4-5 (freshly deposited)"

[0115] As a substrate, a cutting tool body (referred to as a "blank") is used, which is an insert (milling insert) with a geometry of SPHT120408, and a flat insert for coating analysis.

[0116] For the SPHT120408 geometry, the cutting tool body is made of a cemented carbide with the following composition: 90.6 wt% WC, 1.4 wt% (Ta, Nb)C, and 8 wt% Co as a binder phase. The average WC grain size dWC is 0.8 µm.

[0117] For analytical planar inserts, the cutting tool body is made of a cemented carbide with the following composition: 94 wt% WC and 6 wt% Co as a binder phase.

[0118] Prior to deposition, the substrate is pretreated by ultrasonic cleaning in an aqueous medium.

[0119] The PVD reactor was evacuated to 8×10 -5 The substrate is pretreated at 550°C using millibars. The pretreatment includes an Ar ion etching process.

[0120] The coating equipment for depositing coatings according to the present invention is the Hauzer HTC1000 (IHI Hauzer TechnoCoating BV, Netherlands).

[0121] Deposition of the innermost (Ti,Al)N barrier layer: Samples were fabricated, each possessing a distinct innermost (Ti,Al)N thin barrier layer. The deposited barrier layers are Ti... 0.05 Al 0.95 N, Ti 0.10 Al 0.90 N, Ti 0.20 Al 0.80 N, Ti 0.27 Al 0.73 N and Ti 0.33 Al 0.67The N, metal elemental relationship is based on the target composition. As measured by EDX, the Al content immediately after deposition decreases by approximately 5 atomic percent. See Table 1 for details. During deposition, cathodic arc evaporation was used. Circular arc-PVD (CARC+) technology with a constant magnetic field configuration was applied during deposition in a Hauzer HTC1000 instrument. For different samples, TiAl targets were used: "Ti5Al95" (Ti:Al=5:95), "Ti10Al90" (Ti:Al=10:90), "Ti20Al80" (Ti:Al=20:80), "Ti27Al73" (Ti:Al=27:73), and "Ti33Al67" (Ti:Al=33:67). The target diameter was 100 mm. The reactive gas used for nitride deposition was N2. Deposition was carried out under the following conditions: an arc current of approximately 80 A at the target, a bias voltage of -35 V, and an N2 pressure of 10 Pa. The temperature during deposition was approximately 600 °C. A stage rotation speed of 5 rpm was used. The thickness of each deposited thin (Ti,Al)N barrier layer was approximately 50 nm.

[0122] The results show that for Ti 0.05 Al 0.95 N, Ti 0.10 Al 0.90 N and Ti 0.20 Al 0.80 A thin N-layer barrier layer is present, exhibiting a completely wurtzite structure. For Ti... 0.27 Al 0.73 The sample with the N-barrier layer exhibits a mixture of wurtzite and cubic structures, and the area fraction of wurtzite crystallites in the 2D cross-sectional image of this layer is estimated to be much less than 90%. For samples with Ti... 0.33 Al 0.67 The N-barrier layer samples exhibit a pure cubic structure, meaning they do not contain wurtzite. All the Ti-Al relationships in the aforementioned (Ti,Al)N-barrier layers are based on the target composition used in the deposition. EDX can be used to determine the actual Ti-Al relationship in the (Ti,Al)N layer, which may differ slightly from the relationship in the target used.

[0123] Deposition of (Ti,Al)N layers: Then, for each of the five different samples, a (Ti,Al)N layer, referred to herein as the "first metal nitride layer," was deposited. During deposition, cathodic arc evaporation was used. Circular arc-PVD (CARC+) technology using a constant magnetic field configuration was applied during deposition in a Hauzer HTC1000 instrument.

[0124] For the deposition of (Ti,Al)N layers, a TiAl target "Ti50Al50" (Ti:Al = 50:50) was used. The target diameter was 100 mm. The reactive gas for nitride deposition was N2. Deposition was carried out under the following conditions: an arc current of approximately 150 A at the target, a bias voltage of -35 V, and a total pressure of 10 Pa in a pure N2 atmosphere. The temperature during deposition was approximately 600 °C. A stage rotation speed of 3 rpm was used.

[0125] If a target with a specific composition is mentioned in this article, it refers to the fact that, due to the layout of the PVD reactor used, four targets with the same composition are arranged vertically in a row, so that uniform deposition is achieved throughout the height of the reactor.

[0126] The thickness of the deposited (Ti,Al)N layer was approximately 7 µm, and the average value was measured and calculated on the cutting edges (at the start of the cutting edge radius) on both the rake and flank faces.

[0127] The deposited (Ti,Al)N layer is a cubic (Ti,Al)N layer.

[0128] The prepared samples were labeled as "Sample 1 (freshly deposited)", "Sample 2 (freshly deposited)", "Sample 3 (freshly deposited)", "Sample 4 (freshly deposited)" and "Sample 5 (freshly deposited)".

[0129] Table 1. The relationship of metal elements in the target composition Metal elemental relationships from EDX data

[0130] Example 2: Manufacturing of "Sample 6 (freshly deposited)"

[0131] The same base material and the same cutting tool body as in Example 1 are used.

[0132] Deposition of the innermost TiN barrier layer: A sample was prepared having an innermost TiN thin layer. The same substrate material and the same cutting tool body combination as in Example 1 were used.

[0133] In the deposition, cathodic arc evaporation was used. Circular arc-PVD (CARC+) technology with a constant magnetic field configuration was applied during deposition using a Hauzer HTC1000 instrument. A Ti-target with a diameter of 100 mm was used for the sample. N2 was used as the reactive gas for nitride deposition. Deposition was performed under the following conditions: an arc current of approximately 80 A at the target, a bias voltage of -35 V, and an N2 pressure of 10 Pa. The temperature during deposition was approximately 600 °C. A stage rotation speed of 5 rpm was used. The thickness of the deposited thin TiN layer was approximately 50 nm.

[0134] The thin TiN layer has a completely cubic structure.

[0135] Deposition of (Ti,Al)N layers: The same process equipment and process parameters as in Example 1 were used for the deposition of the (Ti,Al)N layer. The thickness of the deposited (Ti,Al)N layer was approximately 7 µm, and the average value was measured and calculated on the cutting edges (at the start of the fillet radius) on both the rake and flank faces. The deposited (Ti,Al)N layer was a cubic (Ti,Al)N layer.

[0136] The prepared sample was labeled "Sample 6 (freshly deposited)".

[0137] Example 3: Fabrication of "Sample 7 (freshly deposited)" and "Sample 8 (freshly deposited)"

[0138] The same base material and the same cutting tool body as in Example 1 are used.

[0139] Deposition of the innermost (Cr,Al)N barrier layer: Samples were prepared, each with a distinct innermost (Cr,Al)N thin barrier layer. The deposited barrier layers are Cr... 0.10 Al 0.90 N and Cr 0.30 Al 0.70 The N, metallic elemental relationship is based on the target composition. The Al content will decrease by several atomic percent immediately after deposition. The same substrate material and the same cutting tool body combination as in Example 1 are used.

[0140] In the deposition, cathodic arc evaporation was used. Circular arc-PVD (CARC+) technology with a constant magnetic field configuration was applied during deposition using a Hauzer HTC1000 instrument. For different samples, CrAl targets "Cr10Al90" (Cr:Al=10:90) and "Cr30Al70" (Cr:Al=30:70) were used, respectively. The target diameter was 100 mm. The reactive gas for nitride deposition was N2. Deposition was carried out under the following conditions: an arc current of approximately 80 A at the target, a bias voltage of -35 V, and an N2 pressure of 10 Pa. The temperature during deposition was approximately 600 °C. A stage rotation speed of 5 rpm was used. The thickness of each deposited thin (Cr,Al)N barrier layer was approximately 50 nm.

[0141] The results showed that Cr 0.10 Al 0.90 The N-thick barrier layer has a completely wurtzite structure. It contains Cr. 0.30 Al 0.70 The N-barrier layer samples have a cubic structure, and wurtzite structures cannot be detected.

[0142] Deposition of (Ti,Al)N layers: The same process equipment and process parameters as in Example 1 were used for the deposition of the (Ti,Al)N layer. The thickness of the deposited (Ti,Al)N layer was approximately 7 µm, and the average value was measured and calculated on the cutting edges (at the start of the fillet radius) on both the rake and flank faces. The deposited (Ti,Al)N layer was a cubic (Ti,Al)N layer.

[0143] The prepared samples were labeled "Sample 7 (freshly deposited)" and "Sample 8 (freshly deposited)".

[0144] Table 2. Relationship of metal elements in the target

[0145] Example 4: Fabrication of "Sample 9 (freshly deposited)" and "Sample 10 (freshly deposited)"

[0146] The same base material and the same cutting tool body as in Example 1 are used.

[0147] Deposition of the innermost (Ti,Al,Si)N barrier layer: Samples were fabricated, each possessing a distinct innermost (Ti, Al, Si)N thin barrier layer. The deposited barrier layers are Ti... 0.35 Al 0.60 Si 0.05 N and Ti 0.35 Al 0.55 Si 0.10The N, metal elemental relationship is based on the target composition. The Al content immediately after deposition will decrease by several atomic percent. The same substrate material and the same cutting tool body combination as in Example 1 were used. Cathodic arc evaporation was used during deposition. Circular arc-PVD (CARC+) technology with a constant magnetic field configuration was applied during deposition in a Hauzer HTC1000 instrument. For different samples, TiAlSi targets "Ti35Al60Si5" (Ti:Al:Si=35:60:5) and "Ti35Al55Si10" (Ti:Al:Si=35:55:10) were used respectively. The target diameter was 100 mm. The reactive gas for nitride deposition was N2. Deposition was performed under the following conditions: arc current at the target of approximately 80 A, bias voltage of -35 V, and N2 pressure of 10 Pa. The temperature during deposition was approximately 600 °C. A stage speed of 5 rpm was used. The thickness of each deposited thin (Ti,Al,Si) N barrier layer was approximately 50 nm.

[0148] The results show that Ti 0.35 Al 0.60 Si 0.05 N-barrier layer and Ti 0.35 Al 0.55 Si 0.10 The N-barrier layers all have a complete wurtzite structure.

[0149] Deposition of (Ti,Al)N layers: The same process equipment and process parameters as in Example 1 were used for the deposition of the (Ti,Al)N layer. The thickness of the deposited (Ti,Al)N layer was approximately 7 µm, and the average value was measured and calculated on the cutting edges (at the start of the fillet radius) on both the rake and flank faces. The deposited (Ti,Al)N layer was a cubic (Ti,Al)N layer.

[0150] The prepared samples were labeled "Sample 9 (freshly deposited)" and "Sample 10 (freshly deposited)".

[0151] Table 3. Relationship of metal elements in the target

[0152] Example 5: Preparation of "Sample 11 (freshly deposited)"

[0153] The same base material and the same cutting tool body as in Example 1 are used.

[0154] Deposition of the innermost (Zr,Ti,Al)N barrier layer: Samples were fabricated, each possessing a distinct innermost (Zr, Ti, Al)N thin barrier layer. The deposited barrier layer is Zr.0.31 Ti 0.34 Al 0.35 The N, metal elemental relationship was measured by EDX. The Al content in the freshly deposited layer was approximately 5 atomic percent lower than the Al content in the target used. The same substrate material and the same cutting tool body combination as in Example 1 were used. Cathodic arc evaporation was used during deposition. Circular arc-PVD (CARC+) technology with a constant magnetic field configuration was applied during deposition in a Hauzer HTC1000 equipment. A ZrTiAl target "Zr40Ti20Al40" (Zr:Ti:Al = 40:20:40) was used. The target diameter was 100 mm. The reactive gas for nitride deposition was N2. Deposition was performed under the following conditions: an arc current of approximately 80 A at the target, a bias voltage of -35 V, and an N2 pressure of 10 Pa. The temperature during deposition was approximately 600 °C. A stage speed of 5 rpm was used. The thickness of the deposited thin (Zr,Ti,Al) N barrier layer was approximately 50 nm.

[0155] The results show that Zr 0.31 Ti 0.34 Al 0.35 The N-barrier layer has a completely wurtzite structure.

[0156] Deposition of (Ti,Al)N layers: The same process equipment and process parameters as in Example 1 were used for the deposition of the (Ti,Al)N layer. The thickness of the deposited (Ti,Al)N layer was approximately 7 µm, and the average value was measured and calculated on the cutting edges (at the start of the fillet radius) on both the rake and flank faces. The deposited (Ti,Al)N layer was a cubic (Ti,Al)N layer.

[0157] The prepared sample was labeled "Sample 11 (freshly deposited)".

[0158] Example 6: Preparation of "Sample 12 (freshly deposited)"

[0159] The same substrate material, cutting tool body, and process as in Example 1 are used, except that no innermost wurtzite-(Ti,Al)N, wurtzite-(Cr,Al)N, wurtzite-(Ti,Al,Si)N, or wurtzite-(Ti,Zr,Al)N thin layer is deposited.

[0160] The thickness of the deposited (Ti,Al)N layer was approximately 7 µm, and the average value was calculated by measuring the cutting edges (at the start of the fillet radius) on both the rake and flank faces. The deposited (Ti,Al)N layer was a cubic (Ti,Al)N layer.

[0161] The prepared sample was labeled "Sample 12 (freshly deposited)".

[0162] All samples 1-12 are shown in Table 4.

[0163] Table 4. Relationship of metal elements in the target When available, metal elemental relationships from EDX data

[0164] Example 7: Preparation of "Sample 13 (freshly deposited)"

[0165] The same base material and the same cutting tool body as in Example 1 are used.

[0166] Deposition of the innermost (Ti,Al)N barrier layer: Using the same process conditions and equipment as in Example 1, the innermost Ti was deposited using a TiAl-target "Ti20Al80" (Ti:Al=20:80) 0.25 Al 0.75 Thin N-barrier layer. The thickness of the deposited thin (Ti,Al)N barrier layer is approximately 50 nm.

[0167] Deposition of (Ti,Al)N layers: Next, a layer different from the (Ti,Al)N layer deposited in the previous example is deposited, which is referred to herein as the "first metal nitride layer". High-power pulsed magnetron sputtering (HIPIMS) was used for deposition. The coating equipment used was an Oerlikon Balzers Ingenia S3p coating system, employing a disk-shaped powder metallurgy composite target with a nominal diameter of 150 mm.

[0168] The PVD reactor was evacuated to 8×10 -5 The substrate is pretreated at 550°C using millibars. The pretreatment includes an Ar ion etching process.

[0169] For the deposition of (Ti,Al)N layers, a TiAl target "Ti40Al60" (Ti:Al = 40:60) was used. The reactive gas for nitride deposition was N2. Deposition was carried out under the following conditions: DC bias of -40 V, total pressure of 0.61 Pa (0.43 Pa Ar + 0.18 Pa N2). The temperature during deposition was approximately 430 °C. Other process parameters were: pulse duration 7.56 ms, duty cycle 15.1%, and pulse power 9 kW.

[0170] By vertically arranging three identical targets in a row, uniform deposition is achieved throughout the height of the reactor.

[0171] The thickness of the deposited (Ti,Al)N layer was approximately 7 µm, and the average value was measured and calculated on the cutting edges (at the start of the cutting edge radius) on both the rake and flank faces.

[0172] The deposited (Ti,Al)N layer is a cubic (Ti,Al)N layer.

[0173] The deposited blade is designated as "Sample 13 (freshly deposited)".

[0174] Example 10 - Heat Treatment

[0175] All the coated cutting tool samples were subjected to heat treatment. This heat treatment was carried out on samples 1-12 at 850°C for 1 hour, wherein the coated cutting tools were surrounded in an Ar protective atmosphere at a pressure of 1 bar.

[0176] First, linearly raise the temperature to 850°C over approximately 45 minutes. Then, maintain the temperature constant for 1 hour. After that, turn off the oven and allow it to cool for approximately 1 to 2 hours.

[0177] For the coated cutting tool of Sample 13, heat treatment was performed at 800°C, 850°C, 900°C, 950°C, and 1000°C for 1 hour, wherein the coated cutting tool was surrounded in an Ar protective atmosphere at a pressure of 1 bar. First, the temperature was linearly increased to the target temperature over approximately 45 minutes. Then, the temperature was held constant for 1 hour. The oven was then closed, and the tool was cooled for approximately 1 to 2 hours. This provides samples after different heat treatments.

[0178] In other respects, sample 3 was also heat-treated at the different temperatures mentioned above in the same manner as sample 13, providing samples that underwent different heat treatments.

[0179] Therefore, heat-treated samples were prepared according to Table 5, wherein the cutting tools of samples 1-13 (freshly deposited) were heat-treated: Table 5. Several samples were prepared, each obtained by heat treatment at a specific temperature specified for the corresponding chromatographic column. The heat-treated samples are shown in Table 6.

[0180] Table 6. Relationship of metal elements in the target When available, metal elemental relationships from EDX data

[0181] Example 11 - Analysis

[0182] To compare samples and evaluate the effects of different (Ti,Al)N barrier layers, a ball cap abrasion test was performed. The amount of peeling was determined visually. A scale from 1 to 6 was used to rate peeling, where 1 indicates a perfect ball cap with no visible peeling, and 6 indicates severe peeling.

[0183] Table 7. The relationship of metal elements in the target composition Metal elemental relationships from EDX data The conclusions from the ball cap grinding test are that samples 1-3, 7, and 9-11 in Table 6, after heat treatment with barrier layers of different types of wurtzite crystal structures, showed good or very good performance in preventing Co diffusion into the (Ti,Al)N layer. Samples 2-3 and 9-11, after heat treatment, showed the best performance. Figure 3 The image shown is of the ball cap cover of sample 12 (HT850℃) (comparative) after grinding, which is rated as level 6 and has severe peeling. Figure 4 The image shown is of the ball cap cover of sample 3 (HT850℃) (invention) after grinding, which is rated as grade 2 and has slight peeling.

[0184] Furthermore, the effect of the (Ti,Al)N barrier layer by performing low-kV EDX analysis was evaluated by comparing the heat-treated sample 3 (HT850℃) (invention) and sample 12 (HT850℃) (comparison).

[0185] Therefore, qualitative elemental mapping was performed on the samples to detect any Co diffusion into the cubic (Ti,Al)N layer after heat treatment. The image shows that sample 12 (HT850℃) (comparative) exhibits significant Co diffusion into the (Ti,Al)N layer. See also Figure 5 This sample does not have any of the internal barrier layers of the present invention. Cobalt (9) is seen extending from the substrate (5) into the (Ti,Al)N layer (7). On the other hand, in samples within the scope of the present invention, no cobalt is seen diffusing into the (Ti,Al)N layer. Figure 6 An elemental mapping image of sample 3 (HT850℃) (invention) is shown.

[0186] Elemental linear distributions were also performed on Sample 3 (HT850℃) (Invention) and Sample 12 (HT850℃) (Comparative). The distributions show that Sample 12 (HT850℃) (Comparative) exhibits a clear signal from cobalt within the cubic (Ti,Al)N layer up to approximately 1 µm. See also Figure 7.on the other hand, Figure 8 The line distribution of elements in sample 3 (HT850℃) (invention) is shown, and it can be seen that no cobalt diffuses into the (Ti,Al)N layer.

[0187] The average Co content within the cubic (Ti,Al)N layer was determined for Sample 3 (HT850℃) (Invention) and Sample 12 (HT850℃) (Comparative) at a distance of 0.2 to 1.2 µm from the substrate-to-coating interface.

[0188] Table 8. Within a distance of 0.2 to 1.2 µm from the substrate-to-coating interface The results from the qualitative elemental mapping and the results from the elemental quantitative line distribution are in excellent agreement with the results of the ball cap grinding test performed on the same sample.

[0189] The analysis results of the fracture toughness of the first metal nitride layer (cubic (Ti,Al)N) in the samples within the scope of this invention are shown in Table 9.

[0190] Table 9.

[0191] Therefore, compared with the freshly deposited (Ti,Al)N layer, the cubic (Ti,Al)N layers deposited in samples 3 and 13 showed a significant improvement in fracture toughness after heat treatment, at least at higher temperatures.

[0192] Because the other samples within the scope of this invention, namely Sample 1 (HT850℃) (Invention), Sample 2 (HT850℃) (Invention), Sample 7 (HT850℃) (Invention), Sample 9 (HT850℃) (Invention), Sample 10 (HT850℃) (Invention), and Sample 11 (HT850℃) (Invention), each, like Sample 3 (HT850℃) (Invention), have the same Ti in their first metal nitride layer. 0.50 Al 0.50 The N-layer designation suggests that all these samples have the same fracture toughness.

[0193] For all samples, the cubic (Ti,Al)N layer contains microcrystals with NaCl structure and microcrystals of grain boundary phase between NaCl structure microcrystals.

[0194] For all samples, the cubic (Ti,Al)N layer contained microcrystals of NaCl structure with different domain types (different elemental compositions).

[0195] Table 10 shows the correlation analysis results of grain boundary phases and different domains in NaCl microcrystals within the cubic (Ti,Al)N layer of the samples within the scope of this invention.

[0196] Table 10.

[0197] Five SEM images were used in the determination of the area fraction of wurtzite, or TEM images were used for the determination of the lowest area fraction.

[0198] To determine the average peak spacing, five microcrystals were analyzed, with 120 intensity lines distributed for each grain in the determination.

[0199] Example 12 - Cutting Test

[0200] Cutting tests were performed to determine the performance of the samples of the present invention.

[0201] Explanation of the terms used: The following expressions / terms are commonly used in metal cutting, but the table below still provides explanations: Vc (m / min): Cutting speed, in meters per minute. fz (mm / tooth): Feed rate, in millimeters per tooth (in milling). fn (mm / revolution) is the feed rate per revolution (during turning). z: (Number) The number of teeth in the cutting tool a e (mm): Radial depth of cut, in millimeters a p (mm): Axial cutting depth, in millimeters. In the milling test, "Sample 3 (HT850℃) (Invention)" and "Sample 12 (HT850℃) (Comparative)" were tested with SPHT120408 milling inserts, and the flank wear was measured. The cutting conditions are summarized in Table 11. The workpiece material used was ISO-P steel, 42CrMo4.

[0202] Cutting conditions: Table 11.

[0203] The wear values ​​(average on the cutting edge) for a cutting length of 8000 mm are shown in Table 12.

[0204] Table 12.

Claims

1. A coated cutting tool (1), said coated cutting tool (1) comprising a substrate body (5) and a coating (6), The substrate is a cemented carbide, and The coating (6) comprises a first metal nitride layer (7) of one or more metal elements from groups 4, 5, and 6 of the periodic table and Al, with a thickness of 0.2 to 25 µm, or of one or more metal elements from groups 4, 5, and 6 of the periodic table and Al and Si. The first metal nitride layer (7) comprises: (i) Microcrystals of the NaCl structure and microcrystals of the grain boundary phase between the microcrystals of the NaCl structure, wherein the microcrystals of the grain boundary phase have a wurtzite crystal structure, and the area fraction of the wurtzite crystal structure in the first metal nitride layer (7) is greater than 0.5% but less than 10%, as measured in 2D cross-sectional images of SEM or TEM. and / or (ii) Microcrystals containing NaCl structures of different domain types, wherein the domain types have different elemental compositions from one another, and the different elemental compositions of the domain types cause repeating peaks in the intensity line distribution analysis of the 2D cross-sectional images of the microcrystals by SEM or TEM, with a peak spacing between the two consecutive peaks, and the average peak spacing is 5 to 30 nm according to the intensity line distribution analysis of the microcrystals. Its features There is an Al layer with a thickness of 10 to 500 nm located below the first metal nitride layer (7). 1-v-y-z M v Si y X z N layers (8), where 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, wherein Al 1-v-y-z M v Si y X z The distance between the N layer (8) and the surface of the substrate body (5) is 0 to 500 nm, M is one or more metallic elements from groups 4, 5 and 6 of the periodic table, X is one or more of C, B and O, and the Al 1-v-y-z M v Si y X z The N layer (8) has a wurtzite crystal structure.

2. The coated cutting tool (1) according to claim 1, wherein the Al 1-v-y-z M v Si y X z The thickness of the N layer (8) is 20 to 300 nm.

3. The coated cutting tool (1) according to any one of claims 1-2, wherein the Al 1-v-y-z M v Si y X z The distance between the N layer (8) and the surface of the substrate body (5) is 0 to 200 nm.

4. The coated cutting tool (1) according to any one of claims 1-3, wherein the Al 1-v-y-z M v Si y X z The N layer (8) is located on the surface of the substrate body (5) and directly below the first metal nitride layer (7).

5. The coated cutting tool (1) according to any one of claims 1-4, wherein in the Al 1-v-y-z M v Si y X z In layer N(8), 0 <v≤0.70,0≤y≤0.15,0≤z≤0.05。 6. The coated cutting tool (1) according to any one of claims 1-5, wherein, In the Al 1-v-y-z M v Si y X z In the N layer (8), M is one or more of Ti, Zr, Hf, V, Nb, Ta and Cr.

7. The coated cutting tool (1) according to any one of claims 1-6, wherein the fracture toughness of the first metal nitride layer (7) is 4.5 to 7.5 MPa. m 0.5 .

8. The coated cutting tool (1) according to any one of claims 1-7, wherein the first metal nitride layer (7) is a metal nitride of one or more of Ti, Cr, Zr, Ta, Nb and V and Al, or a metal nitride of one or more of Ti, Cr, Zr, Ta, Nb and V and Al and Si.

9. The coated cutting tool (1) according to any one of claims 1-8, wherein the substrate is a cemented carbide comprising WC and a binder metal, from the Al 1-v-y-z M v Si y X z Between a distance of 0.2 µm from the interface between the N layer (8) and the first metal nitride layer (7) and a distance of 1.2 µm from the interface, or, if the thickness of the first metal nitride layer (7) is less than 1.2 µm, the content of binder metal in the first metal nitride layer (7) is ≤0.2 atoms from the distance of 0.2 µm to the uppermost surface of the first metal nitride layer (7).

10. The coated cutting tool (1) according to any one of claims 1-9, wherein the substrate body (5) is a WC-Co based cemented carbide containing 5 to 15% by weight Co.

11. The coated cutting tool (1) according to any one of claims 1-10, wherein the cutting tool (1) is a milling cutting insert, a turning cutting insert, a drilling cutting insert, a drill bit, or an end mill.

12. A method for manufacturing a coated cutting tool (1), the method comprising the following steps: - Provides a cemented carbide substrate body (5) - The substrate body (5) is installed in the PVD chamber. - A coating (6) is deposited on the substrate body (5) by a PVD method to form a coated cutting tool (1). The coating (6) comprises: an Al layer with a thickness of 10 to 500 nm. 1-v-y-z M v Si y X z N layers (8), where 0≤v≤0.75, 0≤y≤0.20, 0≤z≤0.10, the Al 1-v-y-z M v Si y X z The N layer has a wurtzite crystal structure; and a first metal nitride layer of 0.2 to 25 µm thickness consisting of one or more metals from Groups 4, 5, and 6 of the periodic table, and Al, or one or more metals from Groups 4, 5, and 6 of the periodic table, and Al and Si (7). The Al 1-v-y-z M v Si y X z The N layer (8) is located below the first metal nitride layer (7), wherein the Al 1-v-y- z M v Si y X z The distance between the N layer (8) and the surface of the substrate body (5) is 0 to 500 nm. - The coated cutting tool (1) is heat-treated at 700 to 1000°C in an atmosphere that prevents oxidation, or in a vacuum, for a period of 10 to 300 minutes.

13. The method of manufacturing a coated cutting tool (1) according to claim 12, wherein the coated cutting tool (1) is heat-treated at 800 to 950°C.

14. The method of manufacturing a coated cutting tool (1) according to any one of claims 12-13, wherein the coated cutting tool (1) is heat-treated for a period of 30 to 150 minutes.

Images