Coated cutting tools

Abstract

The present invention relates to a coated cutting tool (1) for metal machining, comprising a cemented carbide base body (5) and a coating (6) including a layer of metal nitride, wherein the uppermost part of the cemented carbide base body (5) has WC grains including the uppermost WC interface with the coating (6), and a binder phase including the uppermost binder phase interface with the coating (6), and the WC grains including the uppermost WC interface with the coating (6) have an uppermost zone adjacent to the coating (6) which includes W and C, as well as N and one or more of Ti, Cr, Zr, Nb, Mo, and V, the uppermost zone being 1.5 to 8 nm, and the uppermost zone of the WC grains adjacent to the coating (6) which includes any noble gas element or combination of noble gas elements in an amount of ≤0.6 at%.

Description

Technical Field

[0001] The present invention relates to a coated cutting tool for metal machining having a cemented carbide substrate with a coating containing a metal nitride layer.

[0002] Introduction In metal machining operations, cutting tools such as inserts are used. Cutting tools generally have at least one rake face and at least one flank face. A cutting edge exists at the portion where the rake face and the flank face meet. Metal machining operations include, for example, turning, milling, and drilling. Examples of cutting tools include cutting inserts, end mills, and drills.

[0003] In order to provide a long tool life, the cutting tool needs to have high resistance to various types of wear. To improve the wear resistance of cutting tools, various types of wear-resistant coatings are known in the art. Metal nitride layers are commonly used for such wear-resistant coatings. In particular, metal nitrides deposited in physical vapor deposition processes. Examples of metal nitrides include one or more nitrides of titanium, chromium, and zirconium, and in some cases combinations with aluminum and / or silicon. Single layers of metal nitrides or multilayers with alternating sublayers of different metal nitrides can be used.

[0004] Cemented carbide is commonly used as the substrate of coated cutting tools as described above. Cemented carbide contains a hard component of tungsten carbide grains in a binder phase. The binder phase is usually made of cobalt, but other elements such as iron and nickel may be used in the binder composition. Also, some cemented carbides may further contain hard component grains of metal carbides or carbonitrides.

[0005] The influence of the interface properties between the cemented carbide substrate and the metal nitride layer on metal cutting performance is complex. One aspect is the adhesion between the metal nitride layer and the cemented carbide substrate. To achieve high performance in cutting tools, sufficient adhesion is necessary to prevent the coating from peeling off during use. The adhesion of the metal nitride to the substrate may be affected by, for example, the elemental composition of the metal nitride, the residual stress level in the metal nitride layer and on the cemented carbide surface, the surface roughness of the substrate, and the general properties of the interface between the cemented carbide and the metal nitride layer.

[0006] Cutting tools used in metal machining undergo various types of wear during use. Coated cutting tools are affected in various ways by different metal machining operations. For example, turning is a continuous metal machining operation, while milling is actually an intermittent operation.

[0007] One of the most significant types of wear in lathe machining is flank wear, which occurs primarily on the flank surface of the cutting edge due to the abrasion wear mechanism. Because the flank surface is subjected to the movement of the workpiece, excessive flank wear can lead to a decrease in the surface quality of the workpiece, a reduction in the precision of the cutting process, and an increase in friction during the cutting process.

[0008] In milling operations, thermal and mechanical loads change over time. Thermal loads cause thermal tension, which can lead to so-called thermal cracks (referred to herein as "comb cracks") in the coating, while mechanical loads cause cutting edge fatigue, which can lead to chipping, or small fragments of the cutting edge detaching from the rest of the material. Therefore, the common wear types of coated cutting tools in milling operations are cracking and chipping. Thus, high resistance to comb cracks is important for tool life in milling operations, for example. Furthermore, high toughness of the cutting edge is an important characteristic of cutting tools in milling operations.

[0009] Machining ISO-S materials such as titanium and heat-resistant superalloys (HRSA) places special demands on cutting tools. ISO-S materials, for example, have poor thermal conductivity, generating high temperatures during machining and causing wear. Furthermore, their strong work-hardening tendency poses a risk of edge buildup on the cutting tool, affecting workpiece quality, including surface finish defects. Additionally, when machining titanium, problems stemming from its high reactivity can occur, particularly at the high temperatures generated during machining. Typically, smearing is involved in edge formation.

[0010] Furthermore, when machining ISO-M materials, i.e., stainless steel, especially in milling operations, adhesive wear is a significant wear mechanism. Adhesive wear (smearing) is characterized by the formation of a layer of material that can smear and adhere to the cutting edge of a workpiece during the cutting of sticky materials such as stainless steel, potentially forming a so-called built-up edge. Coating delamination is a common problem associated with adhesive wear.

[0011] The properties of the interface between the cemented carbide substrate and the coating on it can affect not only the peeling behavior described above, but also other types of wear, such as lateral wear.

[0012] There is still a need for wear-resistant coated cutting tools that improve tool life. [Overview of the project]

[0013] The objective of the present invention is to provide a coated cutting tool for metal machining that has a long tool life in metal cutting operations. [Brief explanation of the drawing]

[0014] [Figure 1] A schematic diagram is shown illustrating one embodiment of a cutting tool (1) having a rake face 2, a flank face 3, and a cutting edge 4. In this embodiment, the cutting tool 1 is a milling insert. [Figure 2]A schematic diagram is shown illustrating one embodiment of a cutting tool 1 having a rake face 2, a relief face 3, and a cutting edge 4. In this embodiment, the cutting tool 1 is a lathe insert. [Figure 3] This diagram shows a schematic cross-sectional view of one embodiment of a coated cutting tool of the present invention, having a cemented carbide base material 5 and a coating 6. [Figure 4] A schematic diagram of the flank surface 3 of the cutting tool 1 is shown, with the TEM analysis position indicated. [Figure 5a] The intensity curve from the ADF-STEM image of sample 1 (the present invention) is shown. This curve starts from the topmost WC grain and enters the coating. The boundary of the topmost zone defined here can be seen. [Figure 5b] This shows the EELS curve for sample 1 (the present invention) when the coating process begins from within the uppermost WC grains. [Figure 6a] The intensity curve from the ADF-STEM image of sample 2 (the present invention) is shown. This curve starts from the topmost WC grain and enters the coating. The boundary of the uppermost zone defined here can be seen. [Figure 6b] The EELS curve for sample 2 (invention) when the coating enters from within the uppermost WC grain is shown. [Figure 7] The intensity curve from the ADF-STEM image of sample 2 (the present invention) is shown. This curve starts from the distance within the uppermost binder phase below the interface with the coating and enters the coating. The boundary of the uppermost zone defined here can be seen. [Modes for carrying out the invention]

[0015] The present invention provides a coated cutting tool for metal machining that exhibits high lateral wear resistance and / or high peel resistance in metal cutting operations on at least one or more ISO-S and ISO-M workpiece materials. Preferably, the coated cutting tool has high cutting edge toughness and / or high comb-type crack resistance in milling operations on one or more ISO-P, ISO-S, and ISO-M workpiece materials.

[0016] The present invention relates to a coated cutting tool for metal machining, comprising a rake face and a flank face, and a cutting edge between them, further comprising a cemented carbide base body and a coating thereon, wherein the coating comprises a layer of metal nitride MeN with a thickness of 0.2 to 15 μm, where Me is one or more metals from groups 4 to 6 of the periodic table, or a combination of one or more metals from groups 4 to 6 of the periodic table and Al and / or Si, the MeN is a monolithic layer or a multilayer of two or more sublayers with different elemental compositions, and the cemented carbide contains WC in the form of WC grains in the binder phase. - At the top of the cemented carbide substrate body, there are WC grains including the uppermost WC interface with the coating, and a binder phase including the uppermost binder phase interface with the coating. - The WC grains, including the uppermost WC interface with the coating, have an uppermost zone adjacent to the coating that contains, in addition to W and C, N and one or more of Ti, Cr, Zr, Nb, Mo, and V. The uppermost zone is 1.5 to 8 nm, preferably 2 to 6 nm, more preferably 2 to 4 nm, and most preferably 2 to 3.5 nm. - The uppermost zone of the WC grains adjacent to the coating contains <0.6 at% of a noble gas element or combination of noble gas elements. Regarding cutting tools.

[0017] In this context, noble gas elements refer to elements belonging to the group of Ne, Ar, Kr, and Xe.

[0018] The content of noble gas elements is determined here by TEM-EDX.

[0019] The uppermost zone of the WC grains adjacent to the coating preferably contains any noble gas element or combination of noble gas elements in an amount of ≤0.5 at%, preferably ≤0.4 at%, more preferably ≤0.3 at%, even more preferably ≤0.2 at%, most preferably ≤0.1 at%, or does not contain any detectable amount.

[0020] In one embodiment, the uppermost zone of the WC grains adjacent to the coating preferably contains 0.1 at% to 0.6 at% or 0.2 at% to 0.5 at% of a noble gas element or a combination of noble gas elements.

[0021] It has been surprisingly found that by providing an outermost zone of WC grains on the surface of a cemented carbide substrate body having a metal nitride coating on top, a long tool life is provided if the outermost zone of the WC grains contains one or more of Ti, Cr, Zr, Nb, Mo, and V, along with N, and the content of noble gas elements such as Ar, which are commonly used in PVD processes, is very low in the outermost zone. It has been found that the substantial presence of noble gas elements adversely affects the tool life of coated cutting tools with one or more metal nitride layers deposited on a cemented carbide substrate body.

[0022] The coated cutting tools disclosed herein exhibit excellent peel resistance and at least excellent resistance to secondary notch wear, a type of localized flank wear, in finishing turning operations on ISO S workpieces and drilling operations on ISO-S and ISO-M workpieces. They also exhibit high cutting edge toughness and resistance to comb-type cracking in milling operations on ISO P, ISO-S, and ISO-M workpieces.

[0023] In one embodiment, the WC grains, including the uppermost WC interface with the coating, have an uppermost zone adjacent to the coating that includes N and one or more of Ti, Cr, Zr, and V, in addition to W and C.

[0024] In one embodiment, the WC grains, including the uppermost WC interface with the coating, have an uppermost zone adjacent to the coating that includes N and one or more of Ti and Cr, in addition to W and C.

[0025] In one embodiment, the WC grains, including the uppermost WC interface with the coating, have an uppermost zone adjacent to the coating that includes N and Ti in addition to W and C.

[0026] The MeN layer preferably has a thickness of 0.5 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 1 to 3 μm.

[0027] In one embodiment, the MeN layer is the innermost layer of the coating adjacent to the cemented carbide substrate.

[0028] In the MeN layer, Me is preferably one or more of Ti, Cr, and Zr, or a combination of one or more of Ti, Cr, and Zr with Al and / or Si.

[0029] The MeN layer is preferably one of the following: TiN, TiAlN, TiAlSiN, TiAlCrN, TiAlCrSiN, TiAlZrN, TiAlCrAlN, TiAlSiN, CrAlN, or CrAlSiN.

[0030] In one embodiment, the MeN layer is a monolithic layer.

[0031] In one embodiment, the MeN layer is Ti 1-x Al x N is such that 0.35 ≤ x ≤ 0.67, or 0.45 ≤ x ≤ 0.65, or 0.55 ≤ x ≤ 0.62.

[0032] In one embodiment, the MeN layer is Ti 1-p Al p N is such that 0.68 ≤ p ≤ 0.95, or 0.70 ≤ p ≤ 0.90, or 0.75 ≤ p ≤ 0.85.

[0033] In one embodiment, the MeN layer consists of sublayers with alternating different elemental compositions (Me1N, Me2N, ...Me n N is a multilayer structure where n is a number between 2 and 5, or between 2 and 4, or between 2 and 3. Me1, Me2, ...Me n Each of these is one or more metals from groups 4 to 6 of the periodic table, or a combination of one or more metals from groups 4 to 6 of the periodic table with Al and / or Si. The alternating sublayers are Me1N, Me2N, ...Men The average sublayer thickness of (N) is 1 to 100 nm, or 2 to 50 nm, or 3 to 20 nm, respectively.

[0034] In one embodiment, Me1, Me2,... Me n is one or more of Ti, Cr, and Zr, or a combination of one or more of Ti, Cr, and Zr and Al and / or Si.

[0035] Examples of embodiments where MeN is a multilayer include a multilayer of sublayers of TiAlN and TiSiN, a multilayer of sublayers of TiAlN, TiSiN, and CrAlN, a multilayer of sublayers of TiAlN and TiAlSiN, or a multilayer of sublayers of TiAlN and AlCrN.

[0036] In an embodiment where MeN is a multilayer of sublayers of TiAlN and TiSiN, an example of the multilayer is a multilayer of sublayers in which a first sublayer of Ti 1-y Al y N (0.35 ≤ y ≤ 0.70) and a second sublayer of Ti 1-z Si z N (0.12 ≤ z ≤ 0.25) alternate with each other. As another example, there is a multilayer of sublayers in which a first sublayer of Ti 1-u Al ... u N (0.35 ≤ u < 0.67), a second sublayer of Ti 1-v Si v N (0.10 ≤ v ≤ 0.25), and a third sublayer of Ti 1-w Al w N (0.70 ≤ w ≤ 0.90) alternate with each other.

[0037] In an embodiment where MeN is a multilayer of sublayers of TiAlN, TiSiN, and CrAlN, an example of the multilayer is a first sublayer of Ti 1-a Al a N (0.45 ≤ a < 0.67), a second sublayer of Cr 1-b Al b N (0.60 ≤ b ≤ 0.80), and a third sublayer of Ti 1-c Si cThis is a multilayer structure with alternating sublayers, including a third sublayer of type N (0.14 ≤ c ≤ 0.25).

[0038] In embodiments where MeN is a multilayer with TiAlN and TiAlSiN sublayers, an example of the multilayer is Ti 1-d Al d The first sublayer is N (0.55 ≤ d ≤ 0.70), and Ti 1-e-f Al e Si f This is a multilayer structure with alternating sublayers: a second sublayer N (0.20 ≤ e ≤ 0.50, 0.13 ≤ f ≤ 0.25) and another sublayer.

[0039] In embodiments in which MeN is a multilayer with TiAlN and AlCrN sublayers, an example of the multilayer is Ti 1-g AI g The first sublayer is N (0.63 ≤ g ≤ 0.95), and Cr 1-h Al h This is a multilayer structure consisting of alternating layers, with a second sublayer of type N (0.5 ≤ h ≤ 0.9).

[0040] A very thin innermost layer of metal nitride with a different composition from MeN, adjacent to the cemented carbide substrate, generally does not adversely affect the performance of the coated cutting tool. Therefore, in one embodiment, adjacent to the cemented carbide substrate, there is an innermost layer of coating with a thickness of 2-10 nm or 3-5 nm, having a different elemental composition from MeN, which is a nitride of one or more of Ti, Cr, Zr, Nb, Mo, and V, or a nitride of one or more of Ti, Cr, Zr, Nb, Mo, and V combined with Al and / or Si. Examples include TiN, CrN, ZrN, NbN, MoN, and VN. A MeN layer directly follows this innermost layer.

[0041] In another embodiment, there is an innermost layer of coating with a thickness of 2-500 nm, 3-200 nm, or 3-100 nm, which has a different elemental composition from MeN and is a nitride of one or more of Ti, Cr, Zr, Nb, Mo, and V, or a nitride of one or more of Ti, Cr, Zr, Nb, Mo, and V combined with Al and / or Si, and is adjacent to the cemented carbide substrate body. Examples include TiN, CrN, ZrN, NbN, MoN, and VN. Preferably, a MeN layer follows directly from this innermost layer.

[0042] The crystalline structure of WC in the cemented carbide substrate is a hexagonal structure. The MeN layer in this invention is a cubic NaCl structure, or a mixed structure of a hexagonal structure and a cubic NaCl structure.

[0043] The elemental composition is different from MeN, and is a nitride of one or more of Ti, Cr, Zr, Nb, Mo, and V, or a nitride of one or more of Ti, Cr, Zr, Nb, Mo, and V combined with Al and / or Si. The innermost layer of the coating adjacent to the cemented carbide substrate, with a thickness of 2 to 500 nm, 3 to 200 nm, or 3 to 100 nm, preferably has a cubic NaCl structure.

[0044] In the present invention, the uppermost zone of a WC grain, including the uppermost WC interface with the coating, may have a completely cubic NaCl structure. Alternatively, the uppermost zone of a WC grain, including the uppermost WC boundary facing the coating, may include an inner portion with a hexagonal structure, i.e., the portion furthest from the coating, and an upper portion with a cubic NaCl structure, i.e., the portion closest to the coating.

[0045] Therefore, in one embodiment, the crystal structure of the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is a cubic NaCl structure.

[0046] Furthermore, in one embodiment, at least the innermost quarter of the uppermost zone of the WC grain, including the uppermost WC interface with the coating, has a hexagonal structure, and at least the uppermost quarter of the uppermost zone of the WC grain, including the uppermost WC interface with the coating, has a cubic NaCl structure.

[0047] The cubic and hexagonal crystal structures have been appropriately detected by TEM analysis.

[0048] In one embodiment, within the uppermost zone of the WC grains, including the uppermost WC interface with the coating, a discontinuous transition exists in the STEM image, as viewed in the direction toward the coating, from unidirectional lattice patterns continuous with the lattice patterns in the WC to other-directional lattice patterns continuous with the lattice patterns in the innermost part of the coating. The STEM image is created as described herein.

[0049] In one embodiment, within the uppermost zone of a WC grain, including the uppermost WC interface with the coating, the W content decreases from a first content at the lower interface of the uppermost zone of the WC grain to a second content of W at the upper interface of the uppermost zone of the WC grain. The decrease in W content may be substantially continuous or discontinuous, for example, stepwise.

[0050] The first W content in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 40-70 at% or 45-65 at%.

[0051] The second W content in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 5-25 at%, or 8-20 at%.

[0052] In one embodiment, within the uppermost zone of a WC grain, including the uppermost WC interface with the coating, the C content decreases from a first content at the lower interface of the uppermost zone of the WC grain to a second content of C at the upper interface of the uppermost zone of the WC grain. The decrease in C content may be substantially continuous or discontinuous, for example, stepwise.

[0053] The primary content of C in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 20-60 at% or 30-50 at%.

[0054] The second content of C in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 0 to 25 at%, or 2 to 20 at%.

[0055] In one embodiment, within the uppermost zone of a WC grain, including the uppermost WC interface with the coating, the N content increases from a first content at the lower interface of the uppermost zone of the WC grain to a second N content at the upper interface of the uppermost zone of the WC grain. The increase in N content may be substantially continuous or discontinuous, for example, stepwise.

[0056] The primary content of N in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 0 to 15 at%, or 1 to 10 at%.

[0057] The second N content in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 30-55 at% or 35-50 at%.

[0058] In one embodiment, within the uppermost zone of a WC grain, including the uppermost WC interface with the coating, the content of one or more of Ti, Cr, Zr, Nb, Mo, and V increases from a first content at the lower interface of the uppermost zone of the WC grain to a second content of one or more of Ti, Cr, Zr, Nb, Mo, and V at the upper interface of the uppermost zone of the WC grain. The increase in the content of one or more of Ti, Cr, Zr, Nb, Mo, and V may be substantially continuous or discontinuous, for example, stepwise.

[0059] The content of one or more of the first elements, Ti, Cr, Zr, Nb, Mo, and V, in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 0 to 10 at%, or 0 to 5 at%.

[0060] The content of one or more of the second elements, Ti, Cr, Zr, Nb, Mo, and V, in the uppermost zone of the WC grains, including the uppermost WC interface with the coating, is preferably 15-40 at% or 20-35 at%.

[0061] In one embodiment, the uppermost WC interface, measured by cross-sectional cutting with a cutting tool perpendicular to the surface plane of the cemented carbide substrate body, accounts for 75-100% of the total interface between the cemented carbide substrate body and the coating, preferably 80-98%, 85-98%, or 90-96% of the total interface between the cemented carbide substrate body and the coating, measured by cross-sectional cutting with a cutting tool perpendicular to the surface plane of the cemented carbide substrate body.

[0062] In one embodiment, the binder phase has an uppermost zone adjacent to a coating that includes, in addition to the binder metal, N, W, and one or more of Ti, Cr, Zr, Nb, Mo, and V, and the uppermost zone has a thickness of 1 to 5 nm, preferably 1.5 to 3 nm.

[0063] In one embodiment, the uppermost zone of the binder phase adjacent to the coating further includes C.

[0064] In one embodiment, the uppermost zone of the binder phase adjacent to the coating contains ≤1.5 at%, preferably ≤1 at%, of a noble gas element or combination of noble gas elements.

[0065] In one embodiment, the uppermost zone of the binder phase adjacent to the coating preferably contains 0.1 at% to 1.5 at% or 0.2 at% to 1 at% of a noble gas element or combination of noble gas elements.

[0066] The content of noble gas elements is determined here by TEM-EDX.

[0067] In this context, noble gas elements refer to elements belonging to the group of Ne, Ar, Kr, and Xe.

[0068] In one embodiment, within the uppermost zone of the binder phase adjacent to the coating, the binder metal content decreases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating. The decrease in binder metal content may be substantially continuous or discontinuous, for example, stepwise, to the second content.

[0069] The first content of the binder metal in the uppermost zone of the binder phase adjacent to the coating is preferably 20-45 at%.

[0070] The second content of the binder metal in the uppermost zone of the binder phase adjacent to the coating is preferably 0 to 10 at%.

[0071] In one embodiment, within the uppermost zone of the binder phase adjacent to the coating, the N content increases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating. The decrease in N content may be substantially continuous or discontinuous, for example, stepwise, to the second content.

[0072] The primary content of N in the uppermost zone of the binder phase adjacent to the coating is preferably 10 to 30 at%.

[0073] The second N content in the uppermost zone of the binder phase adjacent to the coating is preferably 25-50 at%.

[0074] In one embodiment, the W content is highest in the uppermost zone of the binder phase adjacent to the coating. That is, both the W content at the lower interface of the uppermost zone of the binder phase and the W content at the upper interface adjacent to the coating are lower than the W content at the maximum value.

[0075] The maximum W content in the uppermost zone of the binder phase adjacent to the coating is preferably 5 to 15 at%.

[0076] In one embodiment, within the uppermost zone of the binder phase adjacent to the coating, the content of one or more of Ti, Cr, Zr, Nb, Mo, and V increases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating. The increase in the content of one or more of Ti, Cr, Zr, Nb, Mo, and V may be substantially continuous or may decrease discontinuously, for example, stepwise, to the second content.

[0077] The first content of one or more of Ti, Cr, Zr, Nb, Mo, and V in the uppermost zone of the binder phase adjacent to the coating is preferably 0 to 15 at%, or 3 to 10 at%.

[0078] The content of one or more of the second elements Ti, Cr, Zr, Nb, Mo, and V in the uppermost zone of the binder phase adjacent to the coating is preferably 10-30 at% or 15-25 at%.

[0079] In one embodiment, the uppermost binder phase interface with the coating is measured by cross-sectional cutting of a cutting tool perpendicular to the surface plane of the cemented carbide substrate body and accounts for 0-25%, 2-20%, 2-15%, or 4-10% of the total interface between the cemented carbide substrate body and the coating.

[0080] The base material of the coated cutting tool is a cemented carbide containing WC in the binder phase of a metal binder.

[0081] Preferably, the cemented carbide contains 70-95 wt% WC, or 80-94 wt% WC, or 85-93 wt% WC.

[0082] The metal binder can be any suitable binder metal used for the cemented carbide substrate. Preferably, the metal binder is Co, Ni, or Fe, or a combination thereof. In one embodiment, the metal binder is Co.

[0083] The binder metal content in cemented carbide is appropriately 5-18 wt%, or 6-14 wt%. In addition to WC and the binder metal, cemented carbide may also contain additional components commonly used in the art, such as cubic carbides or carbonitrides of one or more elements from groups 4 and 5 of the periodic table, for example, carbides or carbonitrides of one or more of Ti, Ta, and Nb, also known as the gamma phase, in amounts such as greater than 0 wt% and less than or equal to 25 wt%, or 0.1-10 wt%. The cemented carbide substrate may also contain further components such as Cr.

[0084] In one embodiment, the cemented carbide comprises 5 to 18 wt% or 6 to 14 wt% of a binder metal, 0 to 15 wt% of cubic carbides or carbonitrides of one or more elements from Groups 4 and 5, up to 3 wt% of Cr, up to 300 ppm by weight of one or a metal from Ti, Ta, Nb, V, and Zr, and the remainder being WC.

[0085] The WC particle size is preferably 0.1 to 2 μm, or 0.2 to 1.5 μm, or 0.3 to 1 μm.

[0086] In this specification, the particle size d of WC is determined from the value of its magnetic coercivity. The relationship between the particle size and coercivity of WC is described, for example, in Roebuck et al., Measurement Good Practice No. 20, National Physical Laboratory, ISSN 13686550, November 1999, revised February 2009, Section 3.4.3, p. 1920. In this application, the particle size d of WC is given by equation (8) on page 20 of the above-mentioned document: K=(c1+d1W Co )+(c2+d2W Co It is determined by ) / d. Rearranging, we get the following equation: d=(c²+d²W) Co ) / (K-(c1+d1W Co ))(In the formula, d = grain size of WC of the cemented carbide body, K = coercivity of the cemented carbide body (kA / m) measured in this specification according to DIN IEC standard 60404-7, W Co =Co (weight %) in the cemented carbide body, c1=1.44, c2=12.47, d1=0.04, and d2=-0.37).

[0087] Coated cutting tools are cutting tool inserts, drills, or solid end mills for metal machining. When the cutting tool is an insert, it is preferably a milling cutter, drill, or turning insert.

[0088] One or more layers of the coating are deposited by a PVD process. Any type of PVD process can be used, such as reactive sputtering, HIPIMS, ion plating, or cathode arc deposition. Preferably, a cathode arc deposition process is used.

[0089] Therefore, in one embodiment, both the MeN layer and the innermost layer of the coating, which is 2-500 nm thick, or 3-200 nm thick, or 3-100 nm thick, has a different elemental composition from MeN, and is composed of one or more nitrides from Ti, Cr, Zr, Nb, Mo, and V, or nitrides combining one or more from Ti, Cr, Zr, Nb, Mo, and V with Al and / or Si, and is adjacent to the cemented carbide substrate, are cathode arc deposition layers.

[0090] method: Preparation of TEM lamellae for analysis: Scanning electron microscopes and focused ion beam microscopes (SEM / FIB) (Helios NanoLab 650, FEI) were used to produce site-specific thin lamellae for transmission electron microscopy (TEM). Rare gas content is a defining feature of this invention, and because the use of rare gases in sample preparation can affect subsequent measurements, rare gas ion bombardment should not be used during TEM sample preparation. Standard lift-out techniques were employed, involving one or two low-kV steps of 5kV, and in some cases 2kV. The goal was to make the TEM lamellae thinner than 100nm. TEM lamellae were obtained by cutting the portion including the top of the cemented carbide substrate and the bottom of the coating in a direction perpendicular to the surface of the substrate. The TEM lamellae were cut at a flank located approximately 150–300 μm, preferably approximately 200 μm, from the surface of the rake face, and at least 1 mm away from any other flank faces. See schematic diagram of the location in Figure 4. The TEM lamellae included the total coating thickness of the sample and at least 2 μm of the top layer of the substrate.

[0091] TEM analysis: TEM data, including scanning TEM (STEM) images, EDS, and electron energy loss spectroscopy (EELS) images, were acquired using either a Titan G2 or a Themis aberration-corrected (image and probe) TEM operated at 300 kV. EDX data were acquired with a SuperX detector, and EELS data with a Gatan Quantum ERS system. STEM images were acquired with a camera length of 29.5 mm using Gatan ADF, Gatan HAADF (Titan G2 only), and FEI HAADF detectors. The beam focusing angles were 21.4 mrad for Titan G2 and 21.0 mrad for Themis. The beam current for image acquisition was approximately 100 pA, and the beam current for spectral imaging was 350–600 pA.

[0092] STEM and spectral image analysis was performed using GMS version 3.53 on Titan G2 and GMS version 3.60.4437.0 on Themis. EDX quantification was performed on data extracted from spectral images using Bruker Esprit version 1.9.4.

[0093] Details of EELS characterization: EELS spectral images are obtained using a Gatan GIF Quantum ERS spectrometer with a nominal camera length of 29.5 mm, a C2 50 μm aperture corresponding to a focusing half-angle of 21.3 mrad, and a current of approximately 0.35 nA to 0.4 nA, with a spot size of 9 on Titan G2 and a spot size of 6 on Themis, operated in 300 kV STEM mode. s Image and probe correction were performed using a Titan G2 or Themis 60-300 High Base TEM. For dual EELS spectral imaging, i.e., low-loss and high-loss EELS data, version 2.32.888.0 of the Gatan Digital Micrograph 64-bit software was used with the Titan G2, and version 3.32.2403.0 was used with the Themis. Simultaneously, image data was acquired using the FEI high-angle annular dark-field (HAADF) detector, the Gatan annular dark-field (ADF) detector, and the Gatan HAADF detector (Titan G2 only), and EDX data was acquired using the Super-X EDX detector, which uses all three / four detectors. For acquisition and quantification, a convergence half-angle of 21.3 mrad and a focusing half-angle of 37.8 mrad were used with the Titan G2, and a focusing half-angle of 35.0 mrad was used with the Themis (5 mm GIF aperture). For dual EELS acquisition, an energy dispersion of 1 eV per channel was used. The sharpest point at the interface between the substrate and the coating was identified, and its properties were evaluated.

[0094] For EELS quantification, Gatan GMS 3 Digital Micrograph software (version 3.53.4031.2 for Titan G2, version 3.60.4437.0 for Themis) was used. Spectrum images were used to calculate the EELS curve, and Gatan ADF STEM images were used to extract the intensity profile. In Prefs, under Global Info and Global Tags, the Pre-edge buffer was set to 7.0 eV, the SI background mean nearest neighbor was set to 2, the model was disabled, the Electron Energy Loss Near-Edge Structure (ELNES) was set to FALSE, the background mean was set to TRUE, and ELNES was set to TRUE and excluded. ELNES integral was set to FALSE, Model ELNES was set to TRUE, Splice model ELNES was smoothly set to TRUE, the post-edge delay was set to 50 eV, and Support model ELNES was set to TRUE. The ELNES width was set to 40eV, and the N ELNES iterations were set to 10.

[0095] In the Elemental Quantification window for the map, uncheck the box to disable Model ELNES for 2D SI maps.

[0096] It is important to correct for multiple scatterings using low-loss data, including zero-loss peaks, acquired simultaneously with core-loss data, which includes edge-loss data. During quantification, care was taken to select the chemical shift, ELNES, and signal window so that the modeled ELNES and cross-section curves followed the measured spectral intensities as closely as possible. This was checked and adjusted as necessary for all-element and spectral images of each sample. See below for examples of values ​​used.

[0097] The thickness of the TEM specimens in the analytical region was between approximately 0.7 t / lambda and 1.3 t / lambda.

[0098] Examples of parameter settings used to quantify different elements in EELS spectral images are disclosed below. The exact combination of settings used will depend not only on the elemental composition of the specimen but also on the TEM instrument used to acquire the EELS curve.

[0099] For CK signal extraction, the edge energy was set to 283 eV, the background model to a power law, the fit range to 259.9 to 364.9 eV, the total signal width to 39.1 eV (excluding ELNES), the ELNES width of the model ELNES to 42 eV, N iter 50, the hydrogen cross-section model to a chemical shift of 0 eV, and to include multiple scattering.

[0100] For NK signal extraction, the edge energy was set to 401 eV, overlapping CK was not considered, the background model was set to a power law, the fit range to 350.9 to 583.9 eV, the total signal width to 182.3 eV, the ELNES width of the ELNES model to 46.0 eV, N iter 50, and the hydrogen cross-section model to a chemical shift of -10.0 eV, including multiple scattering.

[0101] For Ti-L signal extraction, the edge energy was set to 455 eV, overlapping NK was not considered, the background model was set to a power law, the fit range to 350.9 to 583.9 eV, the total signal width to 128.5 eV, the ELNES width of the ELNES model to 43.4 eV, N iter 50, and the hydrogen (white line) cross-section model was set to a chemical shift of -8.0 eV, including multiple scattering.

[0102] For Zr-M signal extraction, the following settings were used: edge energy of 180 eV, overlap not considered, background model set to power law, fit range of 166.0 to 240.0 eV, total signal width of 20.0 eV (excluding ELNES), ELNES width of model ELNES of 40.0 eV, Niter 50, Hartree-Slater cross-section model with chemical shift +4.0 eV, including multiple scattering.

[0103] For VL signal extraction, the edge energy was set to 512 eV, overlapping Ti-L was selected, the background model was set to a power law, the fit range to 333.0 to 555.0 eV, the total signal width to 22.1 eV (excluding ELNES), the ELNES width of the model ELNES to 20.0 eV, N iter 50, and the hydrogen (white line) cross-sectional area model was set to chemical shift -7.0 eV, including multiple scattering.

[0104] For Co-L signal extraction, the edge energy was set to 778 eV, overlapping VL and Ti-L were not considered, the background model was set to a power law, the fit range to 624.9 to 1051.9 eV, the total signal width to 233.3 eV, the ELNES width of the model ELNES to 40.0 eV, N iter 50, and the hydrogen cross-section model to have a chemical shift of 0.0 eV and include multiple scattering.

[0105] For Al-K signal extraction, the edge energy was set to 1559 eV, overlapping Co-L was not considered, the background model was set to a power law, the fit range to 1253.9 to 1693.9 eV, the total signal width to 94.3 eV (excluding ELNES), the ELNES width of the model ELNES to 40.0 eV, Niter 50, and the hydrogen cross-section model to a chemical shift of -6.0 eV, including multiple scattering.

[0106] For WM signal extraction, the edge energy was set to 1809 eV, overlapping Al-K was not considered, the background model was set to a power law, the fit range to 1652.9 to 2081.9 eV, the total signal width to 222.7 eV (excluding ELNES), the ELNES width of the model ELNES to 50.0 eV, Niter 50, and the Hartree-Slater cross-section model to have a chemical shift of -3.0 eV and include multiple scattering.

[0107] These examples of parameter settings show the approximate range of variation in chemical shift, ELNES, and signal window values ​​such that the modeled ELNES and cross-sectional curves track the measured spectral intensities as closely as possible.

[0108] Elemental quantification maps were calculated based on the exemplary setup described above. Elemental profiles were extracted perpendicular to the coating-substrate interface, using a subset of the mapping region where the interface was most clearly defined. A width of 50 pixels was used for profile extraction. Step lengths of approximately 1.5 Å and 3 Å were used to acquire DualEELS spectral and STEM images.

[0109] Thickness of the top zone of the WC grain, including the top WC interface with the coating: The thickness of the uppermost zone of a WC grain, including the uppermost WC interface with the coating, is defined herein as follows. Annular dark-field scanning transmission electron microscope (ADF-STEM) images are obtained when the zone axis of the WC grain is aligned parallel to the TEM beam and a bright zone is observed in the uppermost zone of the WC grain, including the uppermost WC interface with the coating.

[0110] The intensity profile diagram corresponding to this bright zone is obtained with the x-axis representing distance in nanometers and the y-axis representing intensity. The maximum intensity of the intensity profile is located within the bright zone of the top zone of the WC grain. The half-value of the maximum peak intensity is calculated from the baseline intensity level at the starting end of the intensity profile along the x-axis, and the corresponding position on the x-axis is considered the innermost boundary of the top zone of the WC grain. Correspondingly, the half-value of the maximum peak intensity is calculated from the baseline intensity level at the ending end of the intensity profile along the x-axis, and the corresponding position on the x-axis is considered the outermost boundary of the top zone of the WC grain. The difference between the two obtained positions on the x-axis is defined as the thickness of the top zone of the WC grain adjacent to the coating. See Figure 5a or Figure 6a for visualization.

[0111] Thickness of the uppermost zone of the binder phase adjacent to the coating: The thickness of the topmost zone of the binder phase adjacent to the coating is defined herein as follows: Annular dark-field scanning transmission electron microscope (ADF-STEM) images are obtained when the zone axis of the binder metal is positioned parallel to the TEM beam and a bright zone is observed in the topmost zone of the binder phase adjacent to the coating. WC grains containing the topmost WC interface with the coating.

[0112] The intensity profile diagram corresponding to this bright zone is obtained with the x-axis representing distance in nanometers and the y-axis representing intensity. The maximum intensity of the intensity profile is located within the bright zone of the topmost zone of the binder phase. The half-value of the maximum peak intensity is calculated from the baseline intensity level at the starting end of the intensity profile along the x-axis, and the corresponding position on the x-axis is considered to be the innermost boundary of the topmost zone of the binder phase adjacent to the coating. Correspondingly, the half-value of the maximum peak intensity is calculated from the baseline intensity level at the ending end of the intensity profile along the x-axis, and the corresponding position on the x-axis is considered to be the outermost boundary of the topmost zone of the binder phase adjacent to the coating. The difference between the two obtained positions on the x-axis is defined as the thickness of the topmost zone of the binder phase adjacent to the coating. See Figure 7 for visualization.

[0113] Determination of noble gas content: The content of noble gases, such as Ar, is determined by analyzing the integrated EDX signal from a rectangular region on the spectral image within the uppermost zone of the WC grain. The determination of noble gases was performed by selecting a rectangular region or binder phase within the uppermost zone of the WC grain or binder phase in the STEM image. The height of the rectangular region was selected to be 1.5–3 nm and positioned in the center of the uppermost zone of the WC grain adjacent to the coating, or the uppermost zone of the binder phase adjacent to the coating. The length of the rectangular region was selected to be at least 10 nm, e.g., 20–30 nm. At least three different uppermost WC grains or uppermost binder phase positions on the cemented carbide substrate are required for the determination.

[0114] In the measurements performed here, the pixel time of the drift-corrected long-exposure map was 20ms, and the number of passes was between 30 and 60.

[0115] If a noble gas element, such as Ar, is present in a constant but very small amount in the uppermost zone or binder phase of a WC grain, and its visible peak is observed in the searched spectrum, then if the rectangular region defined above is moved into pure WC or the coating, the noble gas peak in the spectrum should normally disappear when comparing the spectra of the WC and the coating.

[0116] A method for determining the occupancy ratio of the uppermost WC interface with the coating and the uppermost binder phase interface: The insert was ground and then polished step-by-step using a 1 μm diamond oil slurry on a piece of paper placed on a hard disk, up to the final stage. This method results in very little interface rounding and virtually no preferential etching of binder metals such as Co. The substrate coating interface was measured on the cross-section of the insert. The combination of grinding and polishing removes approximately 1.4 mm of the total width of the insert.

[0117] Measurements were performed at 10,000x magnification, and the total image width was approximately 11.4 μm (high-resolution microscope image 3072 × 2304 pixels, further magnification possible if needed). The areas where the binder metal was in contact with the upper coating were measured and totaled. Subsequently, the coating ratio of the binder phase (total length) relative to WC (total image width) was calculated.

[0118] Measurements were taken at a position approximately 200 μm away from the edge line on the relief side of the insert. The stated values ​​were obtained from the average of measurements taken from images at at least three different positions. A length of at least 10 μm was used per image during the measurement. [Examples]

[0119] Example 1: Sintered cemented carbide cutting tool blanks in the shapes of SNMA120408 (analytical flat insert), CNMG120804-MM and SM (turning inserts), and R390-11T308M-PM (milling insert) were prepared and placed inside a PVD chamber.

[0120] The cemented carbide alloy composition of the CNMG120804-SM insert was 7 wt% Co, 0.7 wt% Cr, 0.01 wt% Ta, 0.014 at% Ti, with the remainder being WC. The cemented carbide alloy composition of the SNMA120804-MM insert and the R390-11T308M-PM insert was 10 wt% Co, 0.4 wt% Cr, with the remainder being WC.

[0121] The WC grain size defined here was 0.4 μm for cemented carbide containing 7 wt% Co, and 0.5 μm for cemented carbide containing 10 wt% Co.

[0122] The cemented carbide blanks were coated by cathode arc deposition in a PVD vacuum chamber containing six arc flanges (each flange containing multiple cathode evaporators).

[0123] Ti40Al60 targets (sources) were mounted on evaporators with three or four flanges of a batch coater equipped with four or six active flanges, respectively. Ti targets (sources) were mounted on one flange. The targets were commercially available circular and flat types with a diameter of 100 mm. The arc source suitable for use in this invention is a Super Fine Cathode (SFC) manufactured by Kobelco (Kobe Steel, Ltd.), which was used in this specification for coating treatment and deposition, except for comparative sample 9. For more information on SFC cathodes, see Yamamoto et al., "Cutting Performance of Low Stress Thick TiAlN PVD Coatings during Machining of Compacted Graphite Cast Iron (CGI)", Coatings 2018, 8, 38; doi:10.3390 / coatings8010038.

[0124] The PVD chamber included a circular, rotatable substrate table, and uncoated cutting tool insert blanks (each having holes like the inserts shown in schematic Figures 1 and 2) were mounted on pins positioned around the circumference of the substrate table. The diameter of the table was 0.82 m. The distance between the circumference of the substrate table and the target was approximately 27 cm.

[0125] The insert was mounted so that its relief surface substantially faced the cathode evaporator as it rotated within the PVD chamber during the sample preparation process.

[0126] The cutting tool insert blank was rotated three times in the PVD chamber during coating deposition. The table rotation speed was 5 rpm.

[0127] Chamber in high vacuum (10 -2 The chamber was evacuated to a pressure of less than Pa and heated to approximately 350-450°C by a heater located inside the chamber.

[0128] The cemented carbide blanks were subjected to the following treatments.

[0129] First, all cemented carbide blanks were subjected to an Ar ion etching process. The purpose of Ar etching is to remove any non-adhered WC fragments that may be present on the substrate surface and to remove any binder phases present in the topmost WC grains facing the surface after ER blasting. In this etching process, the substrate is thoroughly cleaned of such defects. For the following sample preparation, a substrate bias level of -200V and an Ar pressure of approximately 0.7Pa were used, and the average bias current of the substrate table used was approximately 15-17A.

[0130] The experiment was conducted five times with varying processing conditions. Since two different substrates were used, the samples are labeled as 1a, 1b, 2a, 2b, etc. A single sample, such as 1a, contains all the different insert shapes.

[0131] For sample a, the cemented carbide composition was 7 wt% Co, 0.7 wt% Cr, 0.01 wt% Ta, 0.014 at% Ti, with the remainder being WC.

[0132] For sample b, the cemented carbide composition was 10 wt% Co, 0.4 wt% Cr, and the remainder was WC.

[0133] The first step of Ar ion etching was performed in eight separate processes. A DC bias voltage of -200V and an Ar pressure of 0.7Pa were used. The etching time was 55 minutes. The samples are shown in Table 1. TIFF2026509406000002.tif132170

[0134] Subsequently, the Ti ion treatment process was carried out in five separate steps (for samples 1, 2, 3, 5, and 6). In this process, an arc current of 150A was applied to one or more Ti targets in the PVD chamber, and different bias voltage levels were applied to the cutting tool blanks for different treatments, as shown in Table 2. For comparative sample 3, a lower bias voltage level (-100V) was used than that used for the samples in the present invention. Comparative sample 4 thus did not undergo the Ti ion treatment process at all. Subsequently, for comparative samples 5 and 6, much higher bias voltage levels (-1000V and -600V, respectively) were used than those used for the samples in the present invention. For details on Ar gas pressure and treatment time, please refer to Table 2. TIFF2026509406000003.tif103170

[0135] In all samples 1-6, Ti 0.40 Al 0.60 A layer of N was deposited.

[0136] Ti 0.40 Al 0.60 The N layer was deposited by cathode arc deposition in a gas containing N2, using a Ti40Al60-equipped target. 0.40 Al 0.60When depositing the N layer, the substrate bias voltage was -70VDC (relative to the chamber wall), the total pressure (N2) was 4Pa, and the arc current of each cathode was 150A.

[0137] Ti with a thickness of 2 μm 0.40 Al 0.60 The N layer was deposited on the insert (measured at a 200 μm flank from the edge line). This formed the final samples 1 (1a, 1b) (invention), 2 (2a, 2b) (invention), 3 (3a, 3b) (comparison), 4 (4a, 4b) (comparison), 5 (5a, 5b) (comparison), and 6 (6a, 6b) (comparison).

[0138] In Sample 1, the bias was reduced to the level of the nitriding process, causing net Ti deposition, and there was a short period of a few seconds during which one or more Ti targets remained on while the N2 gas rose to the desired pressure. Then, one or more Ti targets were turned off and the Ti-Al targets were ignited. This sequence resulted in the direct deposition of a thin (3-6 nm) layer of TiN on the cemented carbide substrate before the deposition of the TiAlN layer began. Sample 2 was prepared with a modified cycle, and in the corresponding transition sequence from Ti ion treatment to TiAlN deposition, the innermost TiN thin layer was not formed.

[0139] In one of the separate treatments shown in Table 1a (Sample 7), a Zr ion treatment step was performed. In this step, an arc current of 170 A was applied to one or more Zr targets in the PVD chamber, and different bias voltage levels were applied to the cutting tool blank in the different treatments, as shown in Table 3. Ar gas pressure, Ar diffusion For details on processing times, please refer to Table 3. TIFF2026509406000004.tif30170

[0140] In the processing of sample 7, Ti 0.40 Al 0.60 A layer of N was deposited.

[0141] Ti 0.40 Al0.60 The N layer was deposited by cathode arc deposition in a gas containing N2, using a Ti40Al60-equipped target. 0.40 Al 0.60 When depositing the N layer, the substrate bias voltage was -70VDC (relative to the chamber wall), the total pressure (N2) was 4Pa, and the arc current of each cathode was 150A.

[0142] Ti with a thickness of 2 μm 0.40 Al 0.60 The N layer was deposited on the insert (measured at a 200 μm flank from the edge line). This formed the final sample 7(7a, 7b) (the present invention).

[0143] In one of the separate treatments shown in Table 1a (Sample 8), a V-ion treatment step was performed. In this step, an arc current of 170 A was applied to one or more V targets in the PVD chamber, and different bias voltage levels were applied to the cutting tool blank in the different treatments, as shown in Table 4. For details on Ar gas pressure, Ar flow, and treatment time, please refer to Table 4. TIFF2026509406000005.tif30170

[0144] In the processing of sample 8, 0.40 Al 0.60 A layer of N was deposited.

[0145] Ti 0.40 Al 0.60 The N layer was deposited by cathode arc deposition in a gas containing N2, using a Ti40Al60-equipped target. 0.40 Al 0.60 When depositing the N layer, the substrate bias voltage was -70VDC (relative to the chamber wall), the total pressure (N2) was 4Pa, and the arc current of each cathode was 150A.

[0146] Ti with a thickness of 2 μm 0.40 Al 0.60The N layer was deposited on the insert (measured at a 200 μm flank from the edge line). This formed the final sample 8(8a, 8b) (the present invention).

[0147] Finally, the manufacturing process and settings for Sample 2 (the present invention) were repeated, but instead of using Kobelco's (Kobe Steel) Super Fine Cathode (SFC), Kobelco's (Kobe Steel) so-called Fine Cathode (FC) was used. The resulting sample is referred to as Sample 9.

[0148] In this process, a sintered cemented carbide cutting tool insert blank of the same shape as the one used in the production of sample 2, and the same cemented carbide substrate were used.

[0149] First, all cemented carbide blanks were subjected to an Ar ion etching process. The purpose of Ar etching is to remove any loose WC fragments that may be present on the substrate surface and any binder phase present in the topmost WC grains facing the surface after ER blasting. In this etching process, the substrate is thoroughly cleaned from such defects. For the following sample preparation, a substrate bias level of -200V and an Ar pressure of approximately 0.7Pa were used, and the average bias current of the substrate table used was approximately 15-17A.

[0150] The first step of Ar ion etching was performed. The parameters used are shown in Table 5. TIFF2026509406000006.tif35170

[0151] Subsequently, a Ti ion treatment process was carried out. The parameters used are shown in Table 6. TIFF2026509406000007.tif30170

[0152] After that, 0.40 Al 0.60 A layer of N was deposited. 0.40 Al 0.60 The N layer was deposited using the same method and conditions as those used for the preparation of sample 2. The Ti layer was 2 μm thick. 0.40 Al 0.60The N layer was deposited on the insert (measured with a 200 μm flank from the edge line). This formed the final sample 9 (9a, 9b) (comparison).

[0153] Example 2 (TEM analysis): TEM analysis was performed on the samples. The procedure described in the "Methods" section of this specification was followed.

[0154] As described herein, STEM images were obtained to examine the interface between the cemented carbide substrate and the coating.

[0155] For one or more samples within the present invention, the thickness of the uppermost zone of the WC grains, including the uppermost WC interface with the coating, and the thickness of the uppermost zone of the binder phase adjacent to the coating were measured. The procedure described in the "Methods" section of this specification was followed. The results are shown in Table 7.

[0156] The Ar content of the defined uppermost zone (WC grains and binder phase) of the sample was measured. The procedure described in the "Methods" section of this specification was followed. The results are shown in Table 7.

[0157] EELS was used to determine the elemental content within the investigated area, from the cemented carbide substrate to the coating. The procedure described in the "Methods" section of this specification was followed.

[0158] Figure 5a shows the intensity curves from ADF-STEM images of the uppermost WC grains and the area below the coating of sample 1 (the present invention). The boundary of the uppermost zone is as defined here.

[0159] Figure 5b shows the EELS curve of sample 1 (the present invention) when the coating enters from within the WC grain.

[0160] Figure 6a shows the intensity curves from ADF-STEM images of the uppermost WC grains and the area below the coating of sample 2 (the present invention). The boundary of the uppermost zone is as defined here.

[0161] Figure 6b shows the EELS curve of sample 2 (the present invention) when the coating enters from within the WC grain.

[0162] Figure 7 shows intensity curves from ADF-STEM images of the uppermost part of the binder phase and the lower part of the coating of sample 2 (the present invention). The boundary of the uppermost zone is as defined here.

[0163] Table 7, which shows the results of several TEM measurements, indicates the metal used for metal ion treatment and the bias voltage used below the sample number. TIFF2026509406000008.tif180170

[0164] In sample 3 (comparative example) treated with metal ions at -100V, no top layer zone was observed in the binder phases containing WC, W, C, N, and Ti, or in the binder phases containing W, C, N, and Ti, respectively. Instead, a metallic Ti layer approximately 40 nm thick was present as the innermost layer adjacent to the substrate surface.

[0165] In sample 4 (comparative example), which was not treated with metal ions, a very thin (<1 nm) uppermost zone of WC with gradients of W, C, N, and Ti was observed from the EELS data. However, no bright zone was observed in the ADF-STEM image, so the thickness could not be measured according to the method defined herein.

[0166] In sample 5 (comparative example), which underwent metal ion treatment with a bias voltage of -1000V, the Ar content in the uppermost zone of the WC grains adjacent to the coating and the uppermost zone of the binder phase adjacent to the coating was higher than the Ar content in these uppermost zones in the sample within the present invention.

[0167] In sample 6 (comparative example), which underwent metal ion treatment with a bias voltage of -600V, the Ar content in the uppermost zone of the WC grains adjacent to the coating and the uppermost zone of the binder phase adjacent to the coating was much higher than the Ar content in these uppermost zones in the sample according to the present invention.

[0168] In sample 9, no top layer zone was observed in the binder phases containing WC, W, C, N, and Ti, or in the binder phases containing W, C, N, and Ti, respectively. Instead, a metallic Ti layer approximately 50 nm thick was present as the innermost layer adjacent to the substrate surface.

[0169] From the EELS data of Sample 1 (the present invention) and Sample 2 (the present invention), it was concluded that the uppermost zone of the WC grains, including the uppermost WC interface with the coating, contains the elements W, C, Ti, and N.

[0170] The W content decreases from a first content at the lower interface of the uppermost zone of the WC grain to a second content at the upper interface of the uppermost zone of the WC grain. The first W content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 57 at% / 55 at% (Sample 1 / Sample 2). The second W content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 11 at% / 12 at% (Sample 1 / Sample 2).

[0171] The C content decreases from a first content at the lower interface of the uppermost zone of the WC grain to a second content at the upper interface of the uppermost zone of the WC grain. The first C content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 37 at% / 41 at% (Sample 1 / Sample 2). The second C content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 6 at% / 10 at% (Sample 1 / Sample 2).

[0172] The N content increases from a first content at the lower interface of the uppermost zone of the WC grain to a second content at the upper interface of the uppermost zone of the WC grain. The first N content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 2 at% / 1 at% (Sample 1 / Sample 2). The second N content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 47 at% / 42 at% (Sample 1 / Sample 2).

[0173] The Ti content increases from a first Ti content at the lower interface of the uppermost zone of the WC grain to a second Ti content at the upper interface of the uppermost zone of the WC grain. The first Ti content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 0 at% / 0 at% (Sample 1 / Sample 2). The second Ti content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 30 at% / 24 at% (Sample 1 / Sample 2).

[0174] From the EELS data of sample 2 (the present invention), it was concluded that the uppermost zone of the binder phase adjacent to the coating contains the elements Co, W, Ti, and N.

[0175] Furthermore, from the EELS data of sample 2 (the present invention), it was concluded that the Co content decreases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating. The first Co content in the uppermost zone of the binder phase adjacent to the coating is approximately 33 at%. The second Co content in the uppermost zone of the binder phase adjacent to the coating is approximately 5 at%.

[0176] Furthermore, from the EELS data of sample 2 (the present invention), it was concluded that the N content increases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating. The first N content in the uppermost zone of the binder phase adjacent to the coating is approximately 20 at%. The second N content in the uppermost zone of the binder phase adjacent to the coating is approximately 40 at%.

[0177] Furthermore, EELS data from sample 2 (the present invention) showed the maximum W content, and it was concluded that both the W content at the lower interface of the uppermost zone of the binder phase and the W content at the upper interface adjacent to the coating were lower than the W content at the maximum value.

[0178] The maximum W content in the uppermost zone of the binder phase adjacent to the coating is approximately 10 at%.

[0179] Furthermore, from the EELS data of Sample 2 (the present invention), it was concluded that the Ti content increases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating. The first Ti content in the uppermost zone of the binder phase adjacent to the coating is approximately 8 at%. The second Ti content in the uppermost zone of the binder phase adjacent to the coating is approximately 20 at%.

[0180] From the EELS data of sample 7 (invention) and sample 8 (invention), it was concluded that the uppermost zone of the WC grains, including the uppermost WC interface with the coating, contains W, C, Zr, and N, and W, C, V, and N, respectively.

[0181] The W content decreases from a first content at the lower interface of the uppermost zone of the WC grain to a second content at the upper interface of the uppermost zone of the WC grain. The first W content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 53 at% / 44 at% (Sample 7 / Sample 8). The second W content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 16 at% / 16 at% (Sample 7 / Sample 8).

[0182] The C content decreases from a first content at the lower interface of the uppermost zone of the WC grain to a second content at the upper interface of the uppermost zone of the WC grain. The first C content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 38 at% / 38 at% (Sample 7 / Sample 8). The second C content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 16 at% / 12 at% (Sample 7 / Sample 8).

[0183] The N content increases from a first content at the lower interface of the uppermost zone of the WC grain to a second content at the upper interface of the uppermost zone of the WC grain. The first N content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 1 at% / 8 at% (Sample 7 / Sample 8). The second N content in the uppermost zone of the WC grain, including the uppermost WC interface with the coating, is approximately 46 at% / 41 at% (Sample 7 / Sample 8).

[0184] From the EELS data of sample 7 (the present invention), it was concluded that the uppermost zone of the binder phase adjacent to the coating contains the elements Co, W, Zr, and N.

[0185] From the EELS data of sample 8 (the present invention), it was concluded that the uppermost zone of the binder phase adjacent to the coating contains the elements Co, W, V, and N.

[0186] Furthermore, from the EELS data of sample 7 (the present invention), it was concluded that the Co content decreases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating.

[0187] Furthermore, from the EELS data of sample 7 (the present invention), it was concluded that the N content increases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating.

[0188] Furthermore, from the EELS data of sample 8 (the present invention), it was concluded that the Co content decreases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating.

[0189] Furthermore, from the EELS data of sample 8 (the present invention), it was concluded that the N content increases from a first content at the lower interface of the uppermost zone of the binder phase to a second content at the upper interface adjacent to the coating.

[0190] EELS data further confirmed that sample 1 (the present invention) has an innermost TiN layer with a thickness of approximately 4 nm in front of the TiAlN layer.

[0191] The occupancy rate of the uppermost WC interface and the occupancy rate of the uppermost binder phase interface with the coating were measured. The procedure described in the "Methods" section of this specification was followed. The results are shown in Table 8. TIFF2026509406000009.tif30170

[0192] Example 3: A cutting test was conducted to determine the performance of the prepared samples.

[0193] Explanation of terms used: The following terms and phrases are commonly used in metal cutting, and are explained in the table below. TIFF2026509406000010.tif32170

[0194] Last Stage Machining (LSM): Vertical lathe Work material: Inconel 718 aging treatment, hardness 428HB, D=180, L=600mm, Holder: C5-DCLNL-35060-12, KAPR1=95° V c =30m / min(60m / min) f n = 0.11 mm / rotation a p = 0.2 mm Use external cutting fluid

[0195] The tool life criterion is the maximum flank wear (notch) of the secondary cutting edge when VB is 0.2 mm.

[0196] Peeling resistance: The evaluation was performed using a turner test on austenitic steel. The depth of cut a was set to induce adhesive wear and coating delamination. pThe depth was varied between 4-0 mm and 0-4 mm (during a single processing pass in radial facing). The inserts were evaluated by SEM analysis, and the degree of white areas (where the WC was exposed after the coating had peeled off) was quantified by image processing.

[0197] Operation: Facing (lathe) Workpiece material: Austenitic stainless steel bar Sanmac 316L, L=200mm, D=100mm, approx. 215HB Holder: C5-DCLNL-35060-12, KAPR1=95° Insert type: CNMG 120408-MM depth of cut a p =4~0, 0~4mm Cutting speed V c = 100m / min or 140m / min Feed rate f z = 0.36 mm / rotation Cooling: Yes, external

[0198] Edge line toughness (ELT): Operation: Create an opening 12 mm deep in the material. The cutter body moves 12 mm laterally between each opening. Processing material: Deaver unhardened, P3.0.Z.AN, 617*207*100mm Tool holder: R390-032C5-11M, Dc=32mm, Overhang: 95mm Insert: R390-11T308M-PM z=1 V c =215m / min f z = 0.15 mm a e = 12mm a p =3.0 Cutting length = 12mm No cutting fluid was used.

[0199] The cutoff criterion is at least 0.5 mm of chipping of the edge line. Tool life is indicated by the number of cuts required to achieve these criteria.

[0200] Comb-type crack resistance (TTT): Operation: Shoulder milling Tool holder: R390-025B25-11L, Dc=25 mm, overhang 150 mm Work material: Toolox 33 (tool steel, P2.5.Z.HT), L=600mm, I=200mm, h=100mm, Insert type: R390-11T308M-PM Cutting speed V c =275m / min Feed rate f z = 0.2 mm / rotation z=1 Up milling, zero exit angle Cutting depth a p =3mm Radial engagement a e = 12.5 mm Use external cutting fluid The criterion for tool life termination is a maximum chip height VB > 0.3 mm. Each pass is 200mm long.

[0201] In the table showing different test results, the metal used for metal ion treatment and the bias voltage used are indicated below the sample number.

[0202] Last Stage Machining (LSM): Tables 9 to 13 show five different test runs performed with different time intervals, different bar diameters, and / or workpiece batches, which have some effect on tool life (in minutes). Comparative sample 4 has the same coating as the other samples but was prepared without the metal ion treatment process, and can be considered a reference sample to facilitate comparison of the different test runs with each other. TIFF2026509406000011.tif68170TIFF2026509406000012.tif59170TIFF2026509406 000013.tif98170TIFF2026509406000014.tif68170TIFF2026509406000015.tif54170

[0203] In the above LSM tests, it can be concluded that the samples of the present invention showed very good results. Ti ion treatment at -200V showed the best results, but Zr ion treatment at -200V and V ion treatment at -200V also showed significantly better results than the comparative samples that were not treated with any metal ions, or the comparative samples that were treated with metal ions at bias voltages that were too high or too low.

[0204] Therefore, it can be concluded that the bias voltage used during the metal ion treatment process is important. The sample of the present invention was treated using -200V. Comparative samples 3, 5, and 6 were treated with -100V, -600V, and -1000V, respectively, but all showed very poor results in the LSM cutting test.

[0205] The choice of cathode type is also important. When the same conditions (i.e., bias voltage -200V) were used in the Ti processing step, but a so-called fine cathode (FC) manufactured by Kobelco (Kobe Steel) was used instead of a superfine cathode (SFC) manufactured by Kobelco (Sample 9), a net 50nm metallic Ti layer was deposited, resulting in very poor results in the LSM cutting test.

[0206] Turning operation and peel resistance of ISO-M workpiece materials: Tables 14 to 16 show three different test runs performed at different times and with different workpiece batches, which have some influence on the absolute delamination area. TIFF2026509406000016.tif62170TIFF2026509406000017.tif83170

[0207] Milling operation, edge line toughness (ELT), and comb crack resistance (TTT): Tables 16 to 18 show three different test runs performed at different times and with different workpiece batches, which have some effect on absolute tool life. TIFF2026509406000018.tif62170TIFF2026509406000019.tif62170TIFF2026509406000020.tif83170

[0208] Table 19 shows the results of two different test runs conducted at different times, which have some effect on absolute tool life. TIFF2026509406000021.tif48170

Claims

1. A coated cutting tool (1) for metal machining, comprising a rake face (2) and a flank face (3) and a cutting edge (4) between them, wherein the coated cutting tool (1) further comprises a cemented carbide base body (5) and a coating (6) thereon, the coating (6) comprising a layer of metal nitride MeN with a thickness of 0.2 to 15 μm, where Me is one or more metals from groups 4 to 6 of the periodic table, or a combination of one or more metals from groups 4 to 6 of the periodic table and Al and / or Si, the MeN is a monolithic layer or a multilayer of two or more sublayers with different elemental compositions, and the cemented carbide contains WC in the form of WC grains within the binder phase. - At the top of the cemented carbide base material body (5), there are WC grains including the uppermost WC interface with the coating (6), and there is a binder phase including the uppermost binder phase interface with the coating (6). - The WC grains, including the uppermost WC interface with the coating (6), have an uppermost zone adjacent to the coating (6) that contains, in addition to W and C, N and one or more of Ti, Cr, Zr, Nb, Mo, and V, and the uppermost zone is 1.5 to 8 nm, preferably 2 to 6 nm, more preferably 2 to 4 nm. - The uppermost zone of the WC grains adjacent to the coating (6) contains any noble gas element or combination of noble gas elements in an amount of ≤0.6 at%, preferably ≤0.5 at%, more preferably ≤0.4 at%, and more preferably ≤0.3 at%, A coated cutting tool (1).

2. The coated cutting tool (1) according to claim 1, wherein in the MeN layer, Me is one or more of Ti, Cr, and Zr, or a combination of one or more of Ti, Cr, and Zr and Al and / or Si.

3. The MeN layer is the innermost layer of the coating (6) adjacent to the cemented carbide substrate body (5), and the MeN is a sublayer (MeN) with alternating different elemental compositions. １ N, Me ２ N, . . . Me ｎ A coated cutting tool (1) according to claim 1 or 2, wherein N is a multilayer (where n is a number from 2 to 5, or 2 to 4, or 2 to 3). Me １ Me ２ , . . . Me ｎ Each of these is either one or more metals from groups 4 through 6 of the periodic table, or a combination of one or more metals from groups 4 through 6 of the periodic table with Al and / or Si.

4. A coated cutting tool (1), - Within the uppermost zone of the WC grain, including the uppermost WC interface with the coating (6), the W content decreases from the first content at the lower interface of the uppermost zone of the WC grain to the second content of W at the upper interface of the uppermost zone of the WC grain. - Within the uppermost zone of the WC grain, including the uppermost WC interface with the coating (6), the C content decreases from the first content at the lower interface of the uppermost zone of the WC grain to the second content of C at the upper interface of the uppermost zone of the WC grain. - Within the uppermost zone of the WC grain, including the uppermost WC interface with the coating (6), the N content increases from the first content at the lower interface of the uppermost zone of the WC grain to the second content of N at the upper interface of the uppermost zone of the WC grain. - Within the uppermost zone of the WC grains, including the uppermost WC interface with the coating (6), the content of one or more of Ti, Cr, Zr, Nb, Mo, and V increases from a first content at the lower interface of the uppermost zone of the WC grains to a second content of one or more of Ti, Cr, Zr, Nb, Mo, and V at the upper interface of the uppermost zone of the WC grains. A coated cutting tool (1) according to any one of claims 1 to 3.

5. The coated cutting tool (1) according to claim 4, wherein the first W content in the uppermost zone of the WC grains, including the uppermost WC interface with the coating (6), is 40 to 70 at%, and the second W content in the uppermost zone of the WC grains, including the uppermost WC interface with the coating (6), is 5 to 25 at%.

6. The coated cutting tool (1) according to claim 4 or 5, wherein the first carbon content in the uppermost zone of the WC grains, including the uppermost WC interface with the coating (6), is 20 to 60 at%, and the second carbon content in the uppermost zone of the WC grains, including the uppermost WC interface with the coating (6), is 0 to 25 at%.

7. A coated cutting tool (1) according to any one of claims 4 to 6, wherein the first content of N in the uppermost zone of the WC grains including the uppermost WC interface with the coating (6) is 0 to 15 at%, and the second content of N in the uppermost zone of the WC grains including the uppermost WC interface with the coating (6) is 30 to 55 at%.

8. A coated cutting tool (1) according to any one of claims 4 to 7, wherein the content of one or more of Ti, Cr, Zr, Nb, Mo, and V in the uppermost zone of the WC grains including the uppermost WC interface with the coating (6) is 0 to 10 at%, and the content of one or more of Ti, Cr, Zr, Nb, Mo, and V in the uppermost zone of the WC grains including the uppermost WC interface with the coating (6) is 15 to 40 at%,

9. A coated cutting tool (1) according to any one of claims 1 to 8, wherein the uppermost WC interface with the coating (6) accounts for 75 to 100%, or 80 to 98%, of the total interface between the cemented carbide base material (5) and the coating (6), as measured by cross-sectional cutting of the cutting tool (1) perpendicular to the surface plane of the cemented carbide base material (5).

10. A coated cutting tool (1) according to any one of claims 1 to 9, wherein the uppermost binder phase interface with the coating (6) accounts for 0 to 20% or 2 to 15% of the total interface between the cemented carbide substrate (5) and the coating (6), as measured by cross-sectional cutting of a cutting tool perpendicular to the surface plane of the cemented carbide substrate (5).

11. A coated cutting tool (1) according to any one of claims 1 to 10, wherein the binder phase has an uppermost zone adjacent to a coating (6) comprising, in addition to a binder metal, N, W, and one or more of Ti, Cr, Zr, Nb, Mo, and V, and the uppermost zone has a thickness of 1 to 5 nm.

12. The coated cutting tool (1) according to claim 11, wherein the uppermost zone of the binder phase adjacent to the coating (6) contains ≤1.5 at% of a noble gas element or combination of noble gas elements.

13. A coated cutting tool (1) according to any one of claims 1 to 12, wherein the cemented carbide contains 70 to 95 wt% WC.

14. A coated cutting tool (1) according to any one of claims 1 to 13, wherein the binder metal is Co and the binder metal content in the cemented carbide is 5 to 18 wt%.

15. A coated cutting tool (1) according to any one of claims 1 to 14, which is a cutting tool insert, drill, or solid end mill for metal machining.

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