Coated cutting tool

Abstract

The invention relates to a coated cutting tool (1) for metal machining, comprising a cemented carbide matrix (5) and a coating (6) comprising a metal nitride layer, present at the uppermost part of the cemented carbide matrix (5), wherein there are WC grains comprising an uppermost WC interface with the coating (6) and wherein there is a binding phase comprising an uppermost binding phase interface with the coating (6), the WC grains comprising an uppermost WC interface with the coating (6) having an uppermost region adjacent to the coating (6), the coating layer (6) comprises an uppermost region containing N on the basis of containing W and C and containing one or more of Ti, Cr, Zr, Nb, Mo and V, the uppermost region being 1.5 to 8 nm, the uppermost region of the WC grains adjacent to the coating layer (6) containing < 0.6 atom% of any rare gas element or a combination of rare gas elements.

Description

[0001] The invention relates to a coated cutting tool for metal machining, in which a cemented carbide substrate is provided with a coating comprising a metal nitride layer. Background Art

[0002] In metal machining operations, cutting tools such as blades are used. Cutting tools typically have at least one rake face and at least one flank face. The cutting edge is located where the rake and flank faces meet. Metal machining operations include, for example, turning, milling, and drilling. Examples of cutting tools are cutting blades, end mills, and drills.

[0003] In order to provide a long tool life, cutting tools should have a high tolerance to different types of wear. In order to increase the wear resistance of cutting tools, various types of wear-resistant coatings are known in the art. Metal nitride layers are commonly used in such wear-resistant coatings. In particular, metal nitrides deposited during physical vapor deposition processes. Examples of metal nitrides are nitrides of one or more of titanium, chromium and zirconium (sometimes in combination with aluminum and / or silicon). A single layer of metal nitride or a multilayer of alternating sublayers of different metal nitrides can be used.

[0004] Cemented carbide is commonly used as a substrate material in coated cutting tools as discussed above. Cemented carbide comprises a hard component of tungsten carbide grains in a binder phase. Although other elements such as iron and nickel can be used in the binder composition, the binder phase is typically made of cobalt. Additional hard component grains of metal carbides or carbonitrides may also be present in the cemented carbide.

[0005] The influence of the properties of the interface between the cemented carbide substrate and the metal nitride layer on metal cutting performance is complex. One aspect of the interface can be referred to as the adhesion between the metal nitride layer and the cemented carbide substrate. To provide high performance in cutting tools, the adhesion must be sufficiently high to prevent the coating from flaking during use. The adhesion of the metal nitride to the substrate can be influenced by, for example, the elemental composition of the metal nitride, the level of residual stress in the metal nitride layer and at the cemented carbide surface, the roughness of the substrate surface, and the general properties of the interface between the cemented carbide and the metal nitride layer.

[0006] Cutting tools used in metal machining are subject to different types of wear during use. Different metal machining operations affect coated cutting tools in different ways. For example, turning is a continuous metal machining operation, while milling is more intermittent in nature.

[0007] One type of wear that is highly significant in turning operations is flank wear, which occurs on the flank face of the cutting edge and is primarily a result of abrasive wear mechanisms. The flank face is subject to workpiece movement, and excessive flank wear will result in poor surface finish on the workpiece, inaccuracies during cutting, and increased friction during cutting.

[0008] During milling, thermal and mechanical loads vary over time. Thermal loads induce thermal tensions, which can lead to so-called thermal cracks (referred to herein as "comb cracks") in the coating. These can lead to fatigue of the cutting edge, resulting in chipping, where small fragments of the cutting edge break loose from the rest of the substrate. Consequently, common types of wear on coated cutting tools during milling are cracking and chipping. Therefore, high resistance to comb cracking is important for tool life, for example in milling operations. Furthermore, high edge line toughness is an important characteristic of cutting tools in milling operations.

[0009] The machining of 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, which leads to high temperatures during machining and causes wear. Furthermore, the strong work-hardening tendency of ISO-S materials creates the risk of built-up edge formation on cutting tools, which impacts workpiece quality, such as poor surface finish. Furthermore, problems can arise when machining titanium due to its high reactivity, especially at the high temperatures generated during machining. Smearing is often associated with the formation of built-up edge.

[0010] Furthermore, adhesive wear is a significant wear mechanism when machining ISO-M materials, such as stainless steel, particularly in milling operations. Adhesive wear, or the smearing effect, is characterized by the fact that during the cutting process of sticky materials such as stainless steel, workpiece material is smeared and adheres to the cutting edge, creating a layer of material that can form a so-called built-up edge. Spalling of the coating is a common problem associated with adhesive wear.

[0011] The characteristics of the interface between the cemented carbide substrate and the coating thereon may affect not only the spalling behavior as discussed above, but also other types of wear, such as flank wear.

[0012] There is a continuing need for wear resistant coated cutting tools with improved tool life.

[0013] Purpose of the Invention

[0014] It is an object of the present invention to provide a coated cutting tool for metal machining which has a long tool life in metal cutting operations. Summary of the Invention

[0015] A coated cutting tool for metal machining has been provided that exhibits at least high flank wear resistance and / or high chipping resistance in metal cutting operations in one or more of ISO-S and ISO-M workpiece materials. Preferably, the coated cutting tool also has high edge line toughness and / or exhibits high comb crack resistance in milling operations in one or more of 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 with a cutting edge therebetween, the coated cutting tool further comprising a cemented carbide substrate and a coating thereon, wherein the coating comprises a 0.2 to 15 μm thick layer of a metal nitride MeN, wherein 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 with Al and / or Si, the MeN being a monolithic layer or a multilayer of two or more sublayers having different elemental compositions, and the cemented carbide comprising WC in the form of WC grains within a binder phase.

[0017] - an uppermost portion of the cemented carbide substrate is present, wherein WC grains are present comprising an uppermost WC interface with the coating, and wherein a binder phase is present comprising an uppermost binder phase interface with the coating,

[0018] - the WC grains comprising the uppermost WC interface with the coating layer have an uppermost region adjacent to the coating layer, the uppermost region containing N and one or more of Ti, Cr, Zr, Nb, Mo, and V in addition to W and C;

[0019] The uppermost region 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,

[0020] - the uppermost region of the WC grains adjacent to the coating contains <0.6 atomic % of any noble gas element or combination of noble gas elements.

[0021] The rare gas elements herein refer to elements belonging to the group of Ne, Ar, Kr, and Xe.

[0022] The content of noble gas elements was determined by TEM-EDX.

[0023] The uppermost region of the WC grains adjacent the coating suitably contains ≤ 0.5 atomic %, preferably ≤ 0.4 atomic %, more preferably ≤ 0.3 atomic %, even more preferably ≤ 0.2 atomic %, most preferably ≤ 0.1 atomic % of any noble gas element or combination of noble gas elements, or does not contain any detectable amount of any noble gas element or combination of noble gas elements.

[0024] In one embodiment, the uppermost region of the WC grains adjacent the coating suitably comprises ≥ 0.1 atomic % and ≤ 0.6 atomic %, or ≥ 0.2 atomic % and ≤ 0.5 atomic % of any rare gas element or combination of rare gas elements.

[0025] Surprisingly, it has been found that providing an outermost region of WC grains at the surface of a cemented carbide substrate having a metal nitride coating thereon provides long tool life if the outermost region of the WC grains comprises one or more of Ti, Cr, Zr, Nb, Mo, and V, as well as N, and the outermost region has a very low content of any rare gas elements, such as Ar, which is typically used in PVD processes. It has been found that the presence of rare gas elements, if substantial, has a negative impact on the tool life of a coated cutting tool having one or more metal nitride layers deposited on the cemented carbide substrate.

[0026] The coated cutting tools disclosed herein exhibit at least excellent resistance to secondary notch wear, a type of localized flank wear, combined with excellent chipping resistance in finish turning operations on ISO S and drilling operations on ISO-S and ISO-M workpiece materials. Furthermore, they exhibit high edge line toughness and comb crack resistance in milling operations on ISO P, ISO-S, and ISO-M workpiece materials.

[0027] In one embodiment, the WC grains including the uppermost WC interface with the coating layer have an uppermost region adjacent to the coating layer, and the uppermost region contains N and one or more of Ti, Cr, Zr, and V in addition to W and C.

[0028] In one embodiment, the WC grains including the uppermost WC interface with the coating layer have an uppermost region adjacent to the coating layer, and the uppermost region contains N and one or more of Ti and Cr in addition to W and C.

[0029] In one embodiment, the WC grains comprising an uppermost WC interface with the coating layer have an uppermost region adjacent to the coating layer, and the uppermost region further comprises N and Ti in addition to W and C.

[0030] The thickness of the MeN layer is suitably 0.5 to 10 μm, preferably 0.5 to 5 μm, most preferably 1 to 3 μm.

[0031] In one embodiment, the MeN layer is the innermost layer of the coating adjacent to the cemented carbide substrate.

[0032] In the MeN layer, Me is suitably 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.

[0033] The MeN layer is suitably any one of TiN, TiAlN, TiAlSiN, TiAlCrN, TiAlCrSiN, TiAlZrN, TiAlCrAlN, TiAlSiN, CrAlN or CrAlSiN.

[0034] In one embodiment, the MeN layer is a monolithic layer.

[0035] In one embodiment, the MeN layer is Ti 1-x Al x N, 0.35≤x≤0.67, or 0.45≤x≤0.65, or 0.55≤x≤0.62.

[0036] In one embodiment, the MeN layer is Ti 1-p Al p N, 0.68≤p≤0.95, or 0.70≤p≤0.90, or 0.75≤p≤0.85.

[0037] In one embodiment, the MeN layer is an alternating sublayer with different elemental compositions (Me1N, Me2N, ...Me n N, n is a number from 2 to 5, or from 2 to 4, or from 2 to 3). n Each is one or more of Me, wherein Me is one or more metals of Groups 4 to 6 of the Periodic Table, or a combination of one or more metals of Groups 4 to 6 of the Periodic Table and Al and / or Si. n N) are each 1 to 100 nm, or 2 to 50 nm, or 3 to 20 nm in average sublayer thickness.

[0038] In one embodiment, Me1, Me2, ...Me n Each is 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.

[0039] As embodiments in which MeN is a multilayer, there may be mentioned a multilayer of TiAlN and TiSiN sublayers, a multilayer of TiAlN, TiSiN and CrAlN sublayers, a multilayer of TiAlN and TiAlSiN sublayers, or a multilayer of TiAlN and AlCrN sublayers.

[0040] In one embodiment where MeN is a multilayer of TiAlN and TiSiN sublayers, an example of the multilayer is TiN. 1-y Al y The first sublayer of N (0.35≤y≤0.70) and as Ti 1-z Si z Another example is a multilayer of alternating sublayers of a second sublayer of N (0.12≤z≤0.25). 1-u Al u The first sublayer of N (0.35≤u<0.67) as Ti 1-v Si v The second sublayer of N (0.10≤v≤0.25) and as Ti 1-w Al w A multilayer of alternating sublayers of a third sublayer of N (0.70≤w≤0.90).

[0041] In one embodiment where MeN is a multilayer of TiAlN, TiSiN and CrAlN sublayers, an example of the multilayer is TiN. 1-a Al a The first sublayer of N (0.45≤a<0.67), as Cr 1-b Al b The second sublayer of N (0.60≤b≤0.80) and as Ti 1-c Si c A multilayer of alternating sublayers of a third sublayer of N (0.14≤c≤0.25).

[0042] In one embodiment where MeN is a multilayer of TiAlN and TiAlSiN sublayers, an example of the multilayer is Ti 1-d Al d The first sublayer of N (0.55<d≤0.70) and as Ti 1-e-f Al e Si f A multilayer of alternating sublayers of a second sublayer of N (0.20≤e≤0.50, 0.13≤f≤0.25).

[0043] In one embodiment where MeN is a multilayer of TiAlN and AlCrN sublayers, an example of the multilayer is Ti 1-g Al gThe first sublayer of N (where 0.63≤g≤0.95) and as Cr 1-h Al h A multilayer of alternating layers of a second sublayer of N (where 0.5≤h≤0.9).

[0044] A very thin innermost layer of metal nitride, having a composition different from MeN, adjacent to the cemented carbide substrate generally has no negative impact on the performance of the coated cutting tool. Thus, in one embodiment, there is an innermost layer of the coating of 2 to 10 nm, or 3 to 5 nm, thick, having an elemental composition different from MeN, being 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 in combination with Al and / or Si, adjacent to the cemented carbide substrate. Examples include TiN, CrN, ZrN, NbN, MoN, and VN. This innermost layer is directly followed by the MeN layer.

[0045] In another embodiment, there is an innermost layer of the coating having a thickness of 2 to 500 nm, or 3 to 200 nm, or 3 to 100 nm, which has an elemental composition 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 in combination with Al and / or Si, adjacent to the cemented carbide substrate. As examples, TiN, CrN, ZrN, NbN, MoN and VN may be mentioned. This innermost layer is suitably directly followed by the MeN layer.

[0046] The crystal structure of WC in the cemented carbide matrix is ​​a hexagonal crystal structure. The MeN layer in the present invention has a cubic NaCl structure, or a mixture of a hexagonal crystal structure and a cubic NaCl crystal structure.

[0047] The 2 to 500 nm, or 3 to 200 nm, or 3 to 100 nm thick innermost layer of the coating (the innermost layer has an elemental composition different from MeN, is a nitride of one or more of Ti, Cr, Zr, Nb, Mo and V, or is a nitride of one or more of Ti, Cr, Zr, Nb, Mo and V in combination with Al and / or Si, and is adjacent to the cemented carbide substrate) suitably has a cubic NaCl structure.

[0048] In the present invention, the uppermost region of the WC grains including the uppermost WC interface with the coating layer may completely have a cubic NaCl crystal structure. Alternatively, the uppermost region including the WC grains facing the uppermost WC boundary of the coating layer may include an inner portion, i.e., a portion furthest from the coating layer, having a hexagonal crystal structure, and an upper portion, i.e., a portion closest to the coating layer, having a cubic NaCl crystal structure.

[0049] Thus, in one embodiment, the crystal structure of the uppermost region of the WC grains including the uppermost WC interface with the coating is a cubic NaCl structure.

[0050] Furthermore, in one embodiment, at least an innermost quarter of the uppermost region of the WC grains comprising an uppermost WC interface with the coating has a hexagonal crystal structure, and at least an uppermost quarter of the uppermost region of the WC grains comprising an uppermost WC interface with the coating has a cubic NaCl structure.

[0051] Cubic and hexagonal crystal structures are suitably detected by TEM analysis.

[0052] In one embodiment, within the uppermost region of the WC grains including the uppermost WC interface with the coating, there is a discontinuous transition from lattice fringes in one direction continuous with the lattice fringes within the WC to lattice fringes in another direction continuous with the lattice fringes within the innermost portion of the coating as viewed along the coating, as seen in a STEM image prepared as described herein.

[0053] In one embodiment, within the uppermost region of the WC grains including the uppermost WC interface with the coating, the W content decreases from a first content at the lower interface of the uppermost region of the WC grains to a second content of W at the upper interface of the uppermost region of the WC grains. The decrease in W content may be substantially continuous or may be discontinuous, for example, in a stepwise manner.

[0054] The first content of W in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 40 to 70 atomic %, or 45 to 65 atomic %.

[0055] The second content of W in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 5 to 25 atomic %, or 8 to 20 atomic %.

[0056] In one embodiment, within the uppermost region of the WC grains including the uppermost WC interface with the coating, the C content decreases from a first content at the lower interface of the uppermost region of the WC grains to a second content of C at the upper interface of the uppermost region of the WC grains. The decrease in C content may be substantially continuous, or may be discontinuous, for example, in a stepwise manner.

[0057] The first content of C in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 20 to 60 atomic %, or 30 to 50 atomic %.

[0058] The second content of C in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 0 to 25 atomic %, or 2 to 20 atomic %.

[0059] In one embodiment, within the uppermost region of the WC grains including the uppermost WC interface with the coating, the N content increases from a first content at the lower interface of the uppermost region of the WC grains to a second content of N at the upper interface of the uppermost region of the WC grains. The increase in N content may be substantially continuous or may be discontinuous, for example, in a stepwise manner.

[0060] The first content of N in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 0 to 15 atomic %, or 1 to 10 atomic %.

[0061] The second content of N in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 30 to 55 atomic %, or 35 to 50 atomic %.

[0062] In one embodiment, within the uppermost region of the WC grains 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 a lower interface of the uppermost region of the WC grains to a second content of one or more of Ti, Cr, Zr, Nb, Mo, and V at an upper interface of the uppermost region of the WC grains. The increase in the content of one or more of Ti, Cr, Zr, Nb, Mo, and V may be substantially continuous, or may be discontinuous, for example, in a stepwise manner.

[0063] The first content of one or more of Ti, Cr, Zr, Nb, Mo and V in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 0 to 10 atomic %, or 0 to 5 atomic %.

[0064] The second content of one or more of Ti, Cr, Zr, Nb, Mo and V in the uppermost region of the WC grains including the uppermost WC interface with the coating is suitably 15 to 40 atomic %, or 20 to 35 atomic %.

[0065] In one embodiment, the uppermost WC interface accounts for 75% to 100% of the total interface between the cemented carbide substrate and the coating as measured in a cross section of the cutting tool perpendicular to the surface plane of the cemented carbide substrate. Suitably, the uppermost WC interface accounts for 80% to 98%, or 85% to 98%, or 90% to 96% of the total interface between the cemented carbide substrate and the coating as measured in a cross section of the cutting tool perpendicular to the surface plane of the cemented carbide substrate.

[0066] In one embodiment, the binder phase has an uppermost region adjacent to the coating layer, wherein the uppermost region, in addition to containing a binder metal, further comprises N, W, and one or more of Ti, Cr, Zr, Nb, Mo, and V, and the uppermost region has a thickness of 1 to 5 nm, preferably 1.5 to 3 nm.

[0067] In one embodiment, the uppermost region of the binder phase adjacent to the coating further comprises C.

[0068] In one embodiment, the uppermost region of the binder phase adjacent to the coating comprises ≤ 1.5 atomic %, preferably ≤ 1 atomic %, of a noble gas element or a combination of noble gas elements.

[0069] In one embodiment, the uppermost region of the binder phase adjacent to the coating suitably comprises ≥0.1 atomic % and ≤1.5 atomic %, or ≥0.2 atomic % and ≤1 atomic % of any noble gas element or combination of noble gas elements.

[0070] The content of noble gas elements was determined by TEM-EDX.

[0071] The rare gas elements herein refer to elements belonging to the group of Ne, Ar, Kr, and Xe.

[0072] In one embodiment, within the uppermost region of the binder phase adjacent to the coating layer, the binder metal content decreases from a first content at a lower interface of the uppermost region of the binder phase to a second content at an upper interface adjacent to the coating layer. The decrease in binder metal content can be substantially continuous or can follow a discontinuous (e.g., step-wise) decrease to the second content.

[0073] The first content of binder metal in the uppermost region of the binder phase adjacent the coating is suitably 20 to 45 atomic %.

[0074] The second content of binder metal in the uppermost region of the binder phase adjacent the coating layer is suitably 0 to 10 atomic %.

[0075] In one embodiment, within the uppermost region of the binder phase adjacent to the coating layer, the nitrogen content increases from a first content at a lower interface of the uppermost region of the binder phase to a second content at an upper interface adjacent to the coating layer. The decrease in nitrogen content may be substantially continuous or may follow a discontinuous (e.g., step-wise) decrease to the second content.

[0076] The first content of N in the uppermost region of the binder phase adjacent the coating is suitably 10 to 30 atomic %.

[0077] The second content of N in the uppermost region of the binder phase adjacent the coating is suitably 25 to 50 atomic %.

[0078] In one embodiment, the W content is maximum in the uppermost region of the binder phase adjacent to the coating layer, i.e., the W content at the lower interface of the uppermost region of the binder phase and the W content at the upper interface adjacent to the coating layer are both lower than the W content at the maximum point.

[0079] The maximum content of W in the uppermost region of the binder phase adjacent to the coating is suitably 5 to 15 atomic %.

[0080] In one embodiment, within the uppermost region of the binder phase adjacent to the coating layer, the content of one or more of Ti, Cr, Zr, Nb, Mo, and V increases from a first content at a lower interface of the uppermost region of the binder phase to a second content at an upper interface adjacent to the coating layer. The increase in the content of one or more of Ti, Cr, Zr, Nb, Mo, and V may be substantially continuous or may follow a discontinuous (e.g., step-wise) decrease to the second content.

[0081] The first content of one or more of Ti, Cr, Zr, Nb, Mo and V in the uppermost region of the binder phase adjacent the coating is suitably 0 to 15 atomic %, or 3 to 10 atomic %.

[0082] The second content of one or more of Ti, Cr, Zr, Nb, Mo and V in the uppermost region of the binder phase adjacent the coating is suitably 10 to 30 atomic %, or 15 to 25 atomic %.

[0083] In one embodiment, the uppermost binder phase interface with the coating comprises 0% to 25%, or 2% to 20%, or 2% to 15%, or 4% to 10% of the total interface between the cemented carbide substrate and the coating as measured in a cross section of the cutting tool perpendicular to the surface plane of the cemented carbide substrate.

[0084] The substrate of the coated cutting tool is a cemented carbide containing WC in a binder phase of a metal binder.

[0085] Suitably, the cemented carbide comprises 70 to 95 wt% WC, or 80 to 94 wt% WC, or 85 to 93 wt% WC.

[0086] The metal binder may be any suitable binder metal for use in cemented carbide substrates. The metal binder is suitably Co, Ni or Fe or a combination thereof. In one embodiment, the metal binder is Co.

[0087] The binder metal content in the cemented carbide is suitably 5 to 18 wt %, or 6 to 14 wt %. In addition to WC and the binder metal, the 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, such as one or more carbides or carbonitrides of Ti, Ta, and Nb, also known as γ phase, in an amount of, for example, >0 wt % and ≤25 wt %, or 0.1 to 10 wt %. Additional components, such as Cr, may also be present in the cemented carbide substrate.

[0088] In one embodiment, the cemented carbide comprises 5 to 18 wt%, or 6 to 14 wt% binder metal, 0 to 15 wt% cubic carbides or carbonitrides of one or more elements from Groups 4 and 5, up to 3 wt% Cr, up to 300 wtppm of one or more metals selected from Ti, Ta, Nb, V, and Zr, and the balance WC.

[0089] The WC grain size is suitably 0.1 to 2 μm, or 0.2 to 1.5 μm, or 0.3 to 1 μm.

[0090] The WC grain size d is determined herein by the magnetic coercivity value. The relationship between the coercivity and grain size of WC is described, for example, in Roebuck et al., Measurement Good Practice No. 20, National Physical Laboratory, ISSN 1368-6550, November 1999, revised February 2009, Section 3.4.3, pages 19-20. For the purposes of this application, the WC grain size d is determined according to formula (8) on page 20 of the aforementioned document:

[0091] K = (c1+d1W Co ) + (c2+d2W Co ) / d. Rearranging gives:

[0092] d = (c2+d2W Co ) / (K-(c1+d1W Co )),in

[0093] d = WC grain size of the cemented carbide body, K = coercivity of the cemented carbide body in kA / m, measured in this context according to DIN IEC 60404-7, W Co = weight % of Co in the cemented carbide body, c1 = 1.44, c2 = 12.47, d1 = 0.04, d2 = -0.37.

[0094] Described coating cutting tool can be the cutting tool insert, drill or solid end mill that is used for metal machining.When described cutting tool is insert, it is suitably milling, drilling or turning insert.

[0095] The one or more layers of the coating are deposited in a PVD process. Any type of PVD process can be used, such as reactive sputtering, HIPIMS, ion plating or cathodic arc evaporation. Preferably, a cathodic arc evaporation process is used.

[0096] Thus, in one embodiment, the layer of the MeN layer, and in one embodiment the innermost layer of the coating of 2 to 500 nm, or 3 to 200 nm, or 3 to 100 nm thick, are cathodic arc deposited layers, the innermost layer having an elemental composition different from that of MeN, being 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 in combination with Al and / or Si, adjacent to the cemented carbide substrate.

[0097] method:

[0098] Preparation of TEM slices for analysis:

[0099] A scanning electron and focused ion beam microscope (SEM / FIB) (Helios NanoLab 650, FEI) was used to produce position-specific lamellae for transmission electron microscopy (TEM). During the preparation of the TEM samples, no noble gas ion bombardment should be used, since the noble gas content is a defining feature of the invention and the use of noble gases in sample preparation may affect subsequent measurements. Standard lift-off techniques were used with one or two low kV steps, i.e. 5 kV and in some cases 2 kV. TEM lamella thicknesses of less than 100 nm were targeted. The TEM lamellae were obtained by cutting a section comprising the uppermost part of the carbide substrate and the lowermost part of the coating in a direction perpendicular to the surface of the carbide substrate. The TEM lamellae were cut on the back face at a position of about 150 to 300 μm, preferably about 200 μm, from the surface plane of the rake face. In addition, there was a distance of at least 1 mm away from any other back face. See Figure 4 Schematic visualization of the position of the substrate. The TEM lamella contains the entire coating thickness of the sample and at least the uppermost 2 μm of the substrate.

[0100] TEM analysis:

[0101] TEM data, including scanning TEM (STEM) images, EDS and electron energy loss spectroscopy (EELS) images, were collected on a Titan G2 or Themis aberration-corrected (image and probe) TEM operating at 300 kV. EDX data were collected on a SuperX detector, and EELS data were collected on a Gatan Quantum ERS system. STEM images were collected on Gatan ADF, Gatan HAADF (only for Titan G2), and FEI HAADF detectors at a camera length of 29.5 mm. For Titan G2, the beam convergence angle was 21.4 mrad, and for Themis, the beam convergence angle was 21.0 mrad. The beam current used for image acquisition was approximately 100 pA, and the beam current used for spectral imaging was 350-600 pA.

[0102] For Titan G2, STEM image and spectral image analysis were performed on GMS version 3.53, and for Themis, STEM image and spectral image analysis were performed on GMS version 3.60.4437.0. EDX quantification was performed on data extracted from spectral images on Bruker Esprit version 1.9.4.

[0103] EELS characterization details:

[0104] EELS spectral images of C operated in STEM mode s Images and probes were collected on a Titan G2 or Themis 60-300 high-substrate TEM with a spot size of 9 for the Titan G2 and 6 for the Themis at 300 kV using a Gatan GIF Quantum ERS spectrometer with a nominal camera length of 29.5 mm and a C2 50 μm aperture corresponding to a convergence semi-angle of 21.3 mrad. Dual EELS spectral images (low-loss EELS data and high-loss EELS data) were collected using Gatan Digital Micrograph 64-bit software version 2.32.888.0 for the Titan G2 and Gatan Digital Micrograph 64-bit software version 3.32.2403.0 for the Themis. Simultaneously, all three / four detectors were used, and in addition to the EDX data collected with the Super-X EDX detector, image data were collected using a FEI high-angle annular dark field (HAADF) detector, a Gatan annular dark field (ADF) detector, and a Gatan HAADF detector (for Titan G2 only). For acquisition and quantification, a convergence half-angle of 21.3 mrad was used, and for the Titan G2, a collection half-angle of 37.8 mrad and for the Themis, a collection half-angle of 35.0 mrad (5 mm GIF entrance aperture) was used. For dual EELS acquisition, an energy dispersion of 1 eV was used per channel. The region with the sharpest interface between the substrate and the coating was located and characterized.

[0105] For EELS quantification, Gatan GMS 3 Digital Micrograph Software version 3.53.4031.2 was used for the Titan G2, and Gatan GMS 3 Digital Micrograph Software version 3.60.4437.0 was used for the Themis. Spectral images and Gatan ADF STEM images were used to calculate EELS curves and extract intensity distributions, respectively. In quantification, under Prefs, in Global Info and Global Tags, the leading edge buffer was set to 7.0 eV, SI Bkgd average nearest neighbor was set to 2, disable model electron energy loss near edge structure (ELNES) was set to FALSE, Do bkgd averaging was set to TRUE, exclude ELNES was set to TRUE, include ELNES integration was set to FALSE, model ELNES was set to TRUE, smooth stitch model ELNES was set to TRUE, trailing edge delay was set to 50 eV, and support model ELNES was set to TRUE. The ELNES width was set to 40 eV, and N ELNES iterations was set to 10.

[0106] In the Elemental Quantification window for maps, Disable model ELNES' for 2D SI maps is not checked.

[0107] It is important to correct for multiple scattering using low-loss data containing the zero-loss peak, acquired simultaneously with the core-loss data containing the edge. For quantification, the chemical shifts, ELNES, and signal windows are carefully selected so that the simulated ELNES and cross-section curves follow the measured spectral intensities as closely as possible. This is checked for all elements and spectral images for each sample and adjusted if necessary. Examples of the values ​​used are given below.

[0108] The thickness of the TEM sample in the analyzed area is approximately between 0.7 and 1.3 t / λ.

[0109] Below are examples of parameter settings for quantifying different elements in EELS spectral images. The exact combination of settings to be used depends on the TEM instrument used to retrieve the EELS curve and the elemental composition of the sample.

[0110] For CK signal extraction, the edge energy was set to 283 eV, the background model was set to Power Law, the fitting range was 259.9 to 364.9 eV, the signal sum width was set to 39.1 eV (excluding ELNES), the ELNES width of the model ELNES was set to 42 eV, where N iter 50, and the hydrogen-like cross section model had a chemical shift of 0 eV and included multiple scattering.

[0111] For NK signal extraction, the edge energy was set to 401 eV, overlapping CK was not considered, the background model was set to Power Law, the fitting range was 350.9 to 583.9 eV, the signal sum width was set to 182.3 eV, the ELNES width of the model ELNES was set to 46.0 eV with N iter 50, and the hydrogen-like cross section model had a chemical shift of -10.0 eV and included multiple scattering.

[0112] For Ti-L signal extraction, the edge energy was set to 455 eV, overlapping NK was considered, the background model was set to Power Law, the fitting range was 350.9 to 583.9 eV, the signal sum width was set to 128.5 eV, the ELNES width of the model ELNES was set to 43.4 eV, where N iter 50, and the hydrogen-like (with white lines) cross-section model had a chemical shift of -8.0 eV, including multiple scattering.

[0113] For Zr-M signal extraction, the edge energy was set to 180 eV, overlap was not considered, the background model was set to Power Law, the fitting range was 166.0 to 240.0 eV, the signal sum width was set to 20.0 eV (excluding ELNES), the ELNES width of the model ELNES was set to 40.0 eV with a N iter of 50, and the Hartree Slater cross section model had a chemical shift of +4.0 eV, including multiple scattering.

[0114] For VL signal extraction, the edge energy was set to 512 eV, overlap Ti-L was selected, the background model was set to Power Law, the fitting range was 333.0 to 555.0 eV, the signal sum width was set to 22.1 eV (excluding ELNES), the ELNES width of the model ELNES was set to 20.0 eV with N iter 50, and the hydrogen-like (white line) cross section model had a chemical shift of -7.0 eV, including multiple scattering.

[0115] For Co-L signal extraction, the edge energy was set to 778 eV, overlapping VL or Ti-L was not considered, the background model was set to Power Law, the fitting range was 624.9 to 1051.9 eV, the signal sum width was set to 233.3 eV, the ELNES width of the model ELNES was set to 40.0 eV with N iter 50, and the hydrogen-like cross section model had a chemical shift of 0.0 eV and included multiple scattering.

[0116] 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 Power Law, the fitting range was 1253.9 to 1693.9 eV, the signal sum width was set to 94.3 eV (excluding ELNES), the ELNES width of the model ELNES was set to 40.0 eV, where N iter 50, and the hydrogen-like cross section model had a chemical shift of -6.0 eV, including multiple scattering.

[0117] For WM signal extraction, the edge energy was set to 1809 eV, overlapping Al-K was not considered, the background model was set to Power Law, the fitting range was 1652.9 to 2081.9 eV, the signal sum width was set to 222.7 eV (excluding ELNES), the ELNES width of the model ELNES was set to 50.0 eV with N iter 50, and the Hartree-Slater cross section model had a chemical shift of -3.0 eV, including multiple scattering.

[0118] These examples of parameter settings show the values ​​of the chemical shift and the approximate range of variation of the ELNES and signal windows so that the simulated ELNES and cross-section curves follow the measured spectral intensities as well as possible.

[0119] Elemental quantitative mapping was calculated based on the example settings described above. Using a subset of the mapped area with the most clearly defined interface, elemental distributions were extracted perpendicular to the coating-substrate interface. A width of 50 pixels was used for this distribution extraction. For the acquisition of dual EELS spectra and STEM images, step sizes of approximately 1.5 Å and 3 Å were used.

[0120] Thickness of the uppermost region of the WC grain including the uppermost WC interface with the coating:

[0121] The thickness of the uppermost region of the WC grains including the uppermost WC interface with the coating is defined herein as follows: An annular dark field scanning transmission electron microscopy (ADF-STEM) image is obtained when the zone axis of the WC grains is aligned parallel to the beam of the TEM and a bright region is observed in the uppermost region of the WC grains including the uppermost WC interface with the coating.

[0122] An intensity distribution graph corresponding to the bright area is obtained, wherein the x-axis has a scale showing distance in nm and the y-axis has a scale showing intensity. Within the bright area of ​​the uppermost area in the WC grain, there is a maximum intensity in the intensity distribution. A half-maximum peak intensity value is calculated as calculated from the baseline intensity level on one side of the beginning of the intensity distribution along the x-axis, and its corresponding position on the x-axis is considered to be the innermost boundary of the uppermost area of ​​the WC grain. Correspondingly, a half-maximum peak intensity value is calculated as calculated from the baseline intensity level on one side of the end of the intensity distribution along the x-axis, and its corresponding position on the x-axis is considered to be the outermost boundary of the uppermost area of ​​the WC grain. The difference between the two positions obtained on the x-axis is defined as the thickness of the uppermost area of ​​the WC grain adjacent to the coating. See further Figure 5a or 6a for visualization.

[0123] Thickness of the uppermost region of the binder phase adjacent to the coating:

[0124] The thickness of the uppermost region of the binder phase adjacent to the coating is defined as follows. An annular dark field scanning transmission electron microscopy (ADF-STEM) image was obtained when the zone axis of the binder metal was aligned parallel to the beam of the TEM and a bright region was observed in the uppermost region of the binder phase adjacent to the coating, the WC grains comprising the uppermost WC interface with the coating.

[0125] An intensity distribution graph corresponding to the bright area is obtained, wherein the x-axis has a scale showing distance in nm and the y-axis has a scale showing intensity. Within the bright area of ​​the uppermost area in the bonding phase, there is a maximum intensity in the intensity distribution. The half-maximum peak intensity value is calculated as calculated from the baseline intensity level on one side of the beginning of the intensity distribution along the x-axis, and its corresponding position on the x-axis is considered to be the innermost boundary of the uppermost area of ​​the bonding phase adjacent to the coating. Correspondingly, the half-maximum peak intensity value is calculated as calculated from the baseline intensity level on one side of the end of the intensity distribution along the x-axis, and its corresponding position on the x-axis is considered to be the outermost boundary of the uppermost area of ​​the bonding phase adjacent to the coating. The difference between the two positions obtained on the x-axis is defined as the thickness of the uppermost area of ​​the bonding phase adjacent to the coating. See further Figure 7 Used for visualization.

[0126] Determination of rare gas content:

[0127] The noble gas (e.g., Ar) content is determined by analyzing the integrated EDX signal from a rectangular area within the uppermost region of the WC grain on the spectral image. The noble gas determination is performed by selecting a rectangular area within the uppermost region of the WC grain or binder phase in the STEM image. The height of the rectangular area is selected to be 1.5 to 3 nm, and it is placed in the middle of the uppermost region of the WC grain adjacent to the coating or in the middle of the uppermost region of the binder phase adjacent to the coating. The length of the rectangular area is selected to be at least 10 nm, for example, 20 to 30 nm. In the determination, at least three different uppermost WC grains or at least three different uppermost binder phase positions of the cemented carbide substrate should be used.

[0128] In the measurements performed in this paper, the pixel time was 20 ms and the number of passes was between 30 and 60 for long exposure mapping with drift correction.

[0129] There is a certain, but very small, amount of a rare gas element (e.g., Ar) in the uppermost region of the WC grains or binder phase, so that if its visible peak is seen in the retrieved spectrum, then if the rectangular region defined above is moved to pure WC or the coating, the rare gas peak in the spectrum should generally disappear when comparing the spectra in WC and the coating.

[0130] Method for determining the occupancy of the uppermost WC interface and the uppermost binder phase interface with the coating:

[0131] The blade was ground in steps using a 1μm diamond-oil slurry on a paper sheet placed on a hard disk, followed by polishing until the final step. This method resulted in very low interfacial roundness and virtually no preferential etching of binder metals such as Co. Measurements were taken at the substrate-coating interface on a cross-section of the blade. The combination of grinding and polishing removed approximately 1.4mm of the blade's full width.

[0132] The measurement was taken at 10,000X magnification, resulting in a total image width of approximately 11.4 μm (high-resolution micrograph 3072 × 2304 pixels to allow for further zooming if necessary). The area with binder metal contact with the upper coating was measured and summed together. The % coverage of WC (total image width) relative to the binder phase (summed length) was then calculated.

[0133] The measurement is performed on the flank face of the insert at approximately 200 μm from the edge line. The value is obtained by averaging the measurements from at least three different positions on the image. In the measurement, a length of at least 10 μm should be used per image. BRIEF DESCRIPTION OF THE DRAWINGS

[0134] Figure 1A schematic diagram of one embodiment of a cutting tool (1) is shown having a rake face 2 and a flank face 3 and a cutting edge 4. In this embodiment, the cutting tool 1 is a milling insert.

[0135] Figure 2 A schematic diagram of an embodiment of a cutting tool 1 is shown having a rake face 2 and a flank face 3 and a cutting edge 4. In this embodiment, the cutting tool 1 is a turning insert.

[0136] Figure 3 A schematic diagram of a cross section of one embodiment of a coated cutting tool according to the invention is shown, which has a cemented carbide substrate 5 and a coating 6 .

[0137] Figure 4 A schematic diagram of the flank face 3 of a cutting tool 1 is shown, wherein the location for TEM analysis is indicated.

[0138] Figure 5a The intensity curve of the ADF-STEM image from sample 1 (invention) is shown. The curve starts within the uppermost WC grain and enters the coating. The limit of the uppermost region as defined herein is seen.

[0139] Figure 5b Shown is the EELS curve for Sample 1 (Invention) when starting from within the uppermost WC grain and entering the coating.

[0140] Figure 6a The intensity curve of the ADF-STEM image from sample 2 (invention) is shown. The curve starts within the uppermost WC grain and enters the coating. The limit of the uppermost region as defined herein is seen.

[0141] Figure 6b Shown is the EELS curve for Sample 2 (Invention) when starting from within the uppermost WC grain and entering the coating.

[0142] Figure 7 The intensity curve of the ADF-STEM image from Sample 2 (Invention) is shown. The curve starts at a distance within the uppermost binder phase below the interface with the coating and enters the coating. The limit of the uppermost region as defined herein is seen. Example

[0143] Example 1:

[0144] Sintered carbide cutting tool insert blanks with geometries of SNMA 120408 (flat insert for analysis), CNMG 120804-MM and SM (turning inserts), and R390-11T308M-PM (milling inserts) were provided and placed in a PVD chamber.

[0145] For the CNMG120804-SM insert, the cemented carbide composition is 7 wt% Co, 0.7 wt% Cr, 0.01 wt% Ta, and 0.014 atomic % Ti, with the remainder being WC. For the SNMA120804-MM insert and the R390-11T308M-PM insert, the cemented carbide composition is 10 wt% Co, 0.4 wt% Cr, and the remainder being WC.

[0146] As defined herein, for the cemented carbide containing 7 wt% Co, the WC grain size is 0.4 μm, and for the cemented carbide containing 10 wt% Co, the WC grain size is 0.5 μm.

[0147] The cemented carbide blank was coated by cathodic arc evaporation in a PVD vacuum chamber containing six arc flanges, each flange containing several cathode evaporators.

[0148] A target (source) of Ti40Al60 was installed in the evaporator in 3 or 4 flanges of an intermittent coater having 4 or 6 movable flanges, respectively. The Ti target (source) was installed in 1 flange. The target was circular and planar, 100 mm in diameter, and available on the open market. A suitable arc source to be used in the present invention is an arc source called a superfine cathode (SFC) from Kobelco, Kobe Steel Ltd., which was used for the treatment and deposition of the coating herein, except for comparative sample 9. The SFC cathode is discussed in Yamamoto et al., "Cutting Performance of Low Stress Thick TiAlN PVDCoatings during Machining of Compacted Graphite Cast Iron (CGI)", Coatings 2018, 8, 38; doi:10.3390 / coatings8010038.

[0149] The PVD chamber comprises a circular rotatable base table, and uncoated cutting tool insert blanks are mounted on pins located at the circumference of the base table, the uncoated cutting tool insert blanks each having a hole, as shown in the schematic. Figure 1 and 2 The diameter of the platform is 0.82 m. The distance between the circumference of the platform and the target is about 27 cm.

[0150] The blade is mounted such that a relief surface of the blade will substantially face the cathode evaporator during rotation in the PVD chamber during a sample preparation process.

[0151] During the deposition of the coating, the cutting tool insert blank was subjected to a triple rotation in the PVD chamber. The table rotation speed was 5 rpm.

[0152] The chamber was evacuated to a high vacuum (less than 10 -2 Pa) and is heated to about 350-450° C. by a heater located inside the chamber.

[0153] The cemented carbide blank is processed as follows:

[0154] First, all cemented carbide blanks underwent an Ar ion etching step. The purpose of this Ar etching was to remove any loose WC fragments that might be present on the substrate surface. It also removed any binder phase present on the uppermost WC grains facing the surface after ER blasting. During this etching step, the substrate was thoroughly cleaned to remove such defects. In the following sample preparation, a substrate bias level of -200 V and an Ar pressure of approximately 0.7 Pa were used, resulting in an average bias current of approximately 15 to 17 A for the stage used.

[0155] Five separate runs were performed using different process conditions. Since two different substrates were used, the samples are designated 1a, 1b, 2a, 2b, etc. Within the same sample, for example 1a, all the different insert geometries were included.

[0156] For sample "a", the composition of the cemented carbide was 7 wt% Co, 0.7 wt% Cr, 0.01 wt% Ta, and 0.014 atomic% Ti, with the remainder being WC.

[0157] For sample "b", the composition of the cemented carbide was 10 wt% Co, 0.4 wt% Cr, and the remainder WC.

[0158] The first step of Ar ion etching was performed in 8 separate runs. A DC bias voltage of -200 V was used at an Ar pressure of 0.7 Pa. The etching time was 55 min. Table 1 shows the samples.

[0159]

[0160] Then, in five times (sample 1, 2, 3, 5 and 6) in the described independent operation, carried out Ti ion treatment step.In this step, the arc current of 150A is applied on the Ti target in the described PVD chamber, and in different operations, different bias voltage levels are applied on the described cutting tool blank, as shown in Table 2.In comparative sample 3, compared with the bias voltage level used for the sample in the present invention, use lower bias voltage level (-100V).Therefore, comparative sample 4 is not carried out any Ti ion treatment step at all.Then, in comparative samples 5 and 6, compared with the bias voltage level used for the sample in the present invention, use much higher bias voltage level (respectively-1000V and-600V).The other information of Ar gas pressure and treatment time is shown in Table 2.

[0161]

[0162] In all runs of samples 1 to 6, Ti was deposited 0.40 Al 0.60 N layers.

[0163] The Ti 0.40 Al 0.60 The N layer was deposited by cathodic arc evaporation using a mounted Ti40Al60 target in a N2-containing gas. 0.40 Al 0.60 In the N layer, the substrate bias voltage was -70 V DC (relative to the chamber wall), the total pressure (N2) was 4 Pa, and the arc current was 150 A per cathode.

[0164] Ti with a thickness of about 2 μm 0.40 Al 0.60 An N layer was deposited on the insert (measured on the flank face at 200 μm from the edge line). This resulted in 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).

[0165] For Sample 1, there is a short period of several seconds in which the Ti target is still on while the bias voltage has been reduced to the level of the nitride step, resulting in a net deposition of Ti, while the N2 gas is gradually increased to the required pressure. The Ti target is then turned off and the Ti-Al target is ignited. This sequence results in a thin (3-6 nm) TiN layer being deposited directly on top of the cemented carbide substrate before the deposition of the TiAlN layer begins. Sample 2 was made using an altered cycle in which the corresponding transition sequence did not produce any innermost thin TiN layer when proceeding from Ti ion treatment to TiAlN deposition.

[0166] A Zr ion treatment step was performed in one of the individual runs (Sample 7) shown in Table 1. In this step, an arc current of 170 A was applied to the Zr target in the PVD chamber, and different bias voltage levels were applied to the cutting tool blank in different runs, as shown in Table 3. Additional information on Ar gas pressure, Ar flow rate, and treatment time is shown in Table 3.

[0167]

[0168] Then in the run of sample 7, Ti was deposited 0.40 Al 0.60 N layers.

[0169] The Ti 0.40 Al 0.60 The N layer was deposited by cathodic arc evaporation using a mounted Ti40Al60 target in a N2-containing gas. 0.40 Al 0.60 In the N layer, the substrate bias voltage was -70 V DC (relative to the chamber wall), the total pressure (N2) was 4 Pa, and the arc current was 150 A per cathode.

[0170] Ti with a thickness of about 2 μm 0.40 Al 0.60 An N layer was deposited on the insert (measured on the flank face at 200 μm from the edge line). This formed the final sample 7 (7a, 7b) (invention).

[0171] A V ion treatment step was performed in one of the individual runs (Sample 8) shown in Table 1. In this step, an arc current of 170 A was applied to the V target in the PVD chamber, and different bias voltage levels were applied to the cutting tool blank in different runs, as shown in Table 4. Additional information on Ar gas pressure, Ar flow rate, and treatment time is shown in Table 4.

[0172]

[0173] In run 8 of sample, Ti was deposited 0.40 Al 0.60 N layers.

[0174] The Ti 0.40 Al 0.60 The N layer was deposited by cathodic arc evaporation using a mounted Ti40Al60 target in a N2-containing gas. 0.40 Al 0.60In the N layer, the substrate bias voltage was -70 V DC (relative to the chamber wall), the total pressure (N2) was 4 Pa, and the arc current was 150 A per cathode.

[0175] Ti with a thickness of about 2 μm 0.40 Al 0.60 An N layer was deposited on the insert (measured on the flank face at 200 μm from the edge line). This formed the final sample 8 (8a, 8b) (invention).

[0176] Finally, the process and setup for making sample 2 (invention) were repeated, but instead of using the superfine cathode (SFC) from Kobe Steel, a so-called fine cathode (FC) from Kobe Steel was used. The resulting sample is referred to as sample 9.

[0177] Sintered cemented carbide cutting tool insert blanks of the same geometry, and the same cemented carbide substrate as used to make Sample 2 were used in the process.

[0178] First, all cemented carbide blanks underwent an Ar ion etching step. The purpose of this Ar etching was to remove any loose WC fragments that might be present on the substrate surface. It also removed any binder phase present on the uppermost WC grains facing the surface after ER blasting. During this etching step, the substrate was thoroughly cleaned to remove such defects. In the following sample preparation, a substrate bias level of -200 V and an Ar pressure of approximately 0.7 Pa were used, resulting in an average bias current of approximately 15 to 17 A for the stage used.

[0179] The first step of Ar ion etching was performed. The parameters used are shown in Table 5.

[0180]

[0181] Then, the Ti ion treatment step was performed. The parameters used are shown in Table 6.

[0182]

[0183] Then, Ti was deposited 0.40 Al 0.60 N layer. The Ti 0.40 Al 0.60 The N layer was deposited in the same manner and under the same conditions as used to make Sample 2. A Ti layer with a thickness of about 2 μm was deposited. 0.40 Al 0.60 An N layer was deposited on the insert (measured on the flank face at 200 μm from the edge line). This formed the final sample 9 (9a, 9b) (comparison).

[0184] Example 2 (TEM analysis):

[0185] The samples were subjected to TEM analysis following the procedure described herein in the "Methods" section.

[0186] STEM images were acquired as described herein, and the interface region between the cemented carbide substrate and the coating was investigated.

[0187] For the samples within the present invention, the thickness of the uppermost region of the WC grains, including the uppermost WC interface with the coating, and the uppermost region of the binder phase adjacent to the coating were determined. The procedure described in the "Methods" section was followed. See the results in Table 7.

[0188] The Ar content in the defined uppermost region (of the WC grains and binder phase) of the sample was determined. The procedure as described herein in the "Methods" section was followed. See results in Table 7.

[0189] The contents of elements in the studied area from the cemented carbide substrate to the coating were obtained by EELS.The procedure as described herein in the "Methods" section was followed.

[0190] Figure 5a Intensity profiles from an ADF-STEM image of the uppermost WC grain and lower portion of the coating from Sample 1 (Invention) are shown. The limits of the uppermost region are as defined herein.

[0191] Figure 5b Shown is the EELS curve for Sample 1 (Invention) when going from within the WC grains into the coating.

[0192] Figure 6a Intensity profiles from an ADF-STEM image of the uppermost WC grain and lower portion of the coating from Sample 2 (Invention) are shown. The limits of the uppermost region are as defined herein.

[0193] Figure 6b Shown is the EELS curve for sample 2 (invention) when going from within the WC grains into the coating.

[0194] Figure 7 Shown are the intensity profiles of the ADF-STEM images of the uppermost portion of the binder phase and the lower portion of the coating from Sample 2 (Invention). The limits of the uppermost region are as defined herein.

[0195] In Table 7, which presents results from some TEM measurements, under the sample number there is a note of which metal was used in the metal ion treatment and the bias voltage used.

[0196]

[0197] In Sample 3 (Comparative), which was subjected to metal ion treatment at -100 V, there was no uppermost region in the WC containing W, C, N, and Ti, and the binder phase containing W, C, N, and Ti, respectively. Instead, there was a metallic Ti layer of approximately 40 nm thick as the innermost layer adjacent to the substrate surface.

[0198] For sample 4 (comparison), in which no metal ion treatment was performed, there was a very thin (<1 nm) uppermost region in the WC with a gradient of W, C, N, and Ti as seen from the EELS data, but no bright region was seen in the ADF-STEM image, so it was not possible to measure any thickness according to the method defined in this article.

[0199] For Sample 5 (comparative) subjected to metal ion treatment at a bias voltage of -1000 V, the Ar content in the uppermost region of the WC grains adjacent to the coating layer and the Ar content in the uppermost region of the binder phase adjacent to the coating layer were higher than those in the samples according to the present invention.

[0200] In addition, for Sample 6 (comparative) subjected to metal ion treatment at a bias voltage of -600 V, the Ar content in the uppermost region adjacent to the coating in the WC grains and the Ar content in the uppermost region adjacent to the coating in the binder phase were much higher than those in these uppermost regions in the samples within the present invention.

[0201] For sample 9, there is no uppermost region in the WC containing W, C, N and Ti and the binder phase containing W, C, N and Ti, respectively. Instead, there is a metallic Ti layer of about 50 nm thick as the innermost layer adjacent to the substrate surface.

[0202] From the EELS data of Sample 1 (Invention) and Sample 2 (Invention), it was concluded that the uppermost region of the WC grains, including the uppermost WC interface with the coating, contained the elements W, C, Ti, and N.

[0203] The W content decreases from a first content at the lower interface of the uppermost region of the WC grain to a second content of W at the upper interface of the uppermost region of the WC grain. The first content of W in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 57 atomic % / 55 atomic % (Sample 1 / Sample 2). The second content of W in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 11 atomic % / 12 atomic % (Sample 1 / Sample 2).

[0204] The C content decreases from a first content at the lower interface of the uppermost region of the WC grain to a second content of C at the upper interface of the uppermost region of the WC grain. The first content of C in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 37 atomic % / 41 atomic % (Sample 1 / Sample 2). The second content of C in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 6 atomic % / 10 atomic % (Sample 1 / Sample 2).

[0205] The N content increases from a first content at the lower interface of the uppermost region of the WC grain to a second content of N at the upper interface of the uppermost region of the WC grain. The first content of N in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 2 atomic % / 1 atomic % (Sample 1 / Sample 2). The second content of N in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 47 atomic % / 42 atomic % (Sample 1 / Sample 2).

[0206] The Ti content increases from a first content at the lower interface of the uppermost region of the WC grain to a second content of Ti at the upper interface of the uppermost region of the WC grain. The first content of Ti in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 0 atomic % / 0 atomic % (Sample 1 / Sample 2). The second content of Ti in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 30 atomic % / 24 atomic % (Sample 1 / Sample 2).

[0207] Furthermore, it was concluded from the EELS data of Sample 2 (Invention) that the uppermost region of the binder phase adjacent to the coating contained the elements Co, W, Ti, and N.

[0208] Furthermore, the EELS data for Sample 2 (Invention) showed that the Co content decreased from a first content at the lower interface of the uppermost region of the binder phase to a second content at the upper interface adjacent to the coating. The first content of Co in the uppermost region of the binder phase adjacent to the coating was approximately 33 atomic %. The second content of Co in the uppermost region of the binder phase adjacent to the coating was approximately 5 atomic %.

[0209] Furthermore, the EELS data for Sample 2 (Invention) revealed that the N content increased from a first content at the lower interface of the uppermost region of the binder phase to a second content at the upper interface adjacent to the coating layer. The first N content within the uppermost region of the binder phase adjacent to the coating layer was approximately 20 atomic %. The second N content within the uppermost region of the binder phase adjacent to the coating layer was approximately 40 atomic %.

[0210] In addition, it was concluded from the EELS data of Sample 2 (Invention) that the W content showed a maximum, that is, the W content at the lower interface of the uppermost region of the binder phase and the W content at the upper interface adjacent to the coating were both lower than the W content at the maximum.

[0211] The maximum W content in the uppermost region of the binder phase adjacent to the coating layer is about 10 atomic %.

[0212] Furthermore, the EELS data for Sample 2 (Invention) showed that the Ti content increased from a first content at the lower interface of the uppermost region of the binder phase to a second content at the upper interface adjacent to the coating layer. The first Ti content in the uppermost region of the binder phase adjacent to the coating layer was approximately 8 atomic %, and the second Ti content in the uppermost region of the binder phase adjacent to the coating layer was approximately 20 atomic %.

[0213] It was concluded from the EELS data of Sample 7 (Invention) and Sample 8 (Invention) that the uppermost region of the WC grains containing the uppermost WC interface with the coating contained the elements W, C, Ti, and N and W, C, Ti, and N, respectively.

[0214] The W content decreases from a first content at the lower interface of the uppermost region of the WC grain to a second content of W at the upper interface of the uppermost region of the WC grain. The first content of W in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 53 atomic % / 44 atomic % (Sample 7 / Sample 8). The second content of W in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 16 atomic % / 16 atomic % (Sample 7 / Sample 8).

[0215] The C content decreases from a first content at the lower interface of the uppermost region of the WC grain to a second content of C at the upper interface of the uppermost region of the WC grain. The first content of C in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 38 atomic % / 38 atomic % (Sample 7 / Sample 8). The second content of C in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 16 atomic % / 12 atomic % (Sample 7 / Sample 8).

[0216] The N content increases from a first content at the lower interface of the uppermost region of the WC grain to a second content of N at the upper interface of the uppermost region of the WC grain. The first content of N in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 1 atomic % / 8 atomic % (Sample 7 / Sample 8). The second content of N in the uppermost region of the WC grain, including the uppermost WC interface with the coating, is approximately 46 atomic % / 41 atomic % (Sample 7 / Sample 8).

[0217] Furthermore, it was concluded from the EELS data of Sample 7 (Invention) that the uppermost region of the binder phase adjacent to the coating contained the elements Co, W, Zr, and N.

[0218] Furthermore, it was concluded from the EELS data of Sample 8 (Invention) that the uppermost region of the binder phase adjacent to the coating contained the elements Co, W, V, and N.

[0219] Furthermore, it was concluded from the EELS data of Sample 7 (Invention) that the content of Co decreased from a first content at the lower interface of the uppermost region of the binder phase to a second content at the upper interface adjacent to the coating layer.

[0220] Furthermore, it was concluded from the EELS data of Sample 7 (Invention) that the N content increased from a first content at the lower interface of the uppermost region of the binder phase to a second content at the upper interface adjacent to the coating layer.

[0221] Furthermore, it was concluded from the EELS data of Sample 8 (Invention) that the content of Co decreased from a first content at the lower interface of the uppermost region of the binder phase to a second content at the upper interface adjacent to the coating layer.

[0222] Furthermore, it was concluded from the EELS data of Sample 8 (Invention) that the N content increased from a first content at the lower interface of the uppermost region of the binder phase to a second content at the upper interface adjacent to the coating layer.

[0223] EELS data further confirmed that Sample 1 (Invention) had an innermost TiN layer of approximately 4 nm thickness before the TiAlN layer.

[0224] The occupancy of the uppermost WC interface to the total interface between the cemented carbide substrate and the coating, as well as the occupancy of the uppermost binder phase interface with the coating, was determined. The procedure described herein in the "Methods" section was followed. Table 8 shows the results.

[0225]

[0226] Example 3:

[0227] Cutting tests were performed to determine the properties of the prepared samples.

[0228] Explanation of terms used:

[0229] The following expressions / terms are commonly used in metal cutting but are explained in the table below:

[0230] Vc (m / min): cutting speed, in meters per minute

[0231] fz (mm / tooth): feed rate in millimeters / tooth (in milling)

[0232] fn (mm / rev): feed rate / rev (in turning)

[0233] z (number): number of teeth on the tool

[0234] a e (mm): Radial cutting depth, in millimeters

[0235] a p (mm): Axial cutting depth, in millimeters

[0236] Final stage machining (LSM):

[0237] Longitudinal turning

[0238] Workpiece material: Aged Inconel 718, hardness 428HB, D = 180, L = 600mm,

[0239] Bracket: C5-DCLNL-35060-12, KAPR1 = 95°

[0240] V c = 30m / min (60m / min)

[0241] f n = 0.11mm / revolution

[0242] a p = 0.2mm

[0243] With external cutting fluid

[0244] The tool life criterion is a maximum flank wear (notch) VB of 0.2 mm on the secondary cutting edge.

[0245] Peel resistance:

[0246] The evaluation was carried out by turning tests in austenitic steel. In order to induce adhesive wear and peeling of the coating, the cutting depth a p Varies between 4 to 0 mm and 0 to 4 mm (in one run during radial facing). The inserts were evaluated by SEM analysis, where the spalling area was quantified by image processing with respect to the extent of white areas (WC exposed after coating spalling).

[0247] Operation: facing (turning)

[0248] Workpiece material: Austenitic stainless steel bar Sanmac 316L, L = 200mm, D = 100mm, about 215 HB

[0249] Bracket: C5-DCLNL-35060-12, KAPR1 = 95°

[0250] Blade type: CNMG 120408-MM

[0251] Cutting depth a p = 4 to 0 mm, 0 to 4 mm

[0252] Cutting speed V c = 100m / min or 140m / min

[0253] Feed rate f z = 0.36mm / revolution

[0254] Cooling: Yes, external

[0255] Edge Line Toughness (ELT):

[0256] Operation: 12mm deep entry into the material. The tool body moves 12mm laterally between each entry.

[0257] Workpiece material: Unhardened Dievar, P3.0.Z.AN, 617×207×100mm

[0258] Tool holder: R390-032C5-11M, Dc = 32mm, cantilever: 95mm

[0259] Blade: R390-11T308M-PM

[0260] z = 1

[0261] V c = 215m / min

[0262] f z = 0.15mm

[0263] a e = 12mm

[0264] a p = 3.0

[0265] Cutting length = 12mm

[0266] No cutting fluid

[0267] The cut-off criterion is a chipping of at least 0.5 mm at the edge line. The tool life is expressed as the number of cutting entries required to achieve these criteria.

[0268] Comb crack resistance (TTT):

[0269] Operation: Shoulder milling

[0270] Tool holder: R390-025B25-11L, Dc = 25mm, cantilever 150mm

[0271] Workpiece material: Toolox 33 (tool steel, P2.5.Z.HT), L = 600mm, I = 200mm, h = 100mm,

[0272] Blade type: R390-11T308M-PM

[0273] Cutting speed V c = 275m / min

[0274] Feed rate f z = 0.2mm / revolution

[0275] z = 1

[0276] Upward milling, zero degree exit

[0277] Cutting depth a p = 3mm

[0278] Radial engagement a e = 12.5mm

[0279] With external cutting fluid

[0280] The criterion for the end of tool life is that the maximum chipping height VB>0.3mm.

[0281] Each pass is 200mm

[0282] In the tables presenting the results from the different tests, under the sample number there is a note which metal was used in the metal ion treatment and the bias voltage used.

[0283] Final stage machining (LSM):

[0284] Tables 9 to 13 show five different test runs performed at different times and with different rod diameters and / or workpiece batches, which in some way influence the tool life in minutes. Comparative sample 4, which was produced with the same coating as the other samples but without any metal ion treatment step, can be considered a reference sample, making it easier to compare the different test runs with each other.

[0285]

[0286]

[0287]

[0288]

[0289]

[0290] It was concluded that the samples within the present invention performed very well in the above-mentioned LSM test. The best results were obtained with the Ti ion treatment at -200 V, and good results were also obtained with the Zr ion treatment at -200 V and the V ion treatment at -200 V. These results were much higher than those of the comparative samples in which no metal ion treatment was used at all or in which the metal ion treatment was performed at too high a bias voltage or too low a bias voltage.

[0291] Therefore, it was concluded that the bias voltage used during the metal ion treatment step is important. The samples within the present invention were processed using -200 V. Comparative samples 3, 5, and 6 were processed using -100 V, -600 V, and -1000 V, respectively, and all gave very poor results in the LSM cutting test.

[0292] The choice of cathode type is also important. When the same conditions (i.e., -200 V bias voltage) were used in the Ti processing step, instead of using a super fine cathode (SFC) from Kobelco, a so-called fine cathode (FC) from Kobelco (Sample 9) was used, there was a net deposition of a 50 nm metallic Ti layer and very poor results in the LSM cutting test.

[0293] Turning operations of ISO-M workpiece materials, chipping resistance:

[0294] Tables 14 to 16 show three different test runs performed at different times and with different batches of workpieces, which to some extent influence the absolute spalling area.

[0295]

[0296]

[0297] Milling operations, Edge Line Toughness (ELT) and Comb Toughness (TTT):

[0298] Tables 16 to 18 show three different test runs performed at different times and with different workpiece batches, which to some extent influence the absolute tool life.

[0299]

[0300]

[0301]

[0302] Table 19 shows the results of two different test runs performed at different times, which affects the absolute tool life to some extent.

[0303]

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) therebetween, the coated cutting tool (1) further comprising a cemented carbide substrate (5) and a coating (6) thereon, wherein the coating (6) comprises a 0.2 to 15 μm thick layer of a metal nitride MeN, wherein Me is one or more metals from Groups 4 to 6 of the Periodic Table of Elements, or a combination of one or more metals from Groups 4 to 6 of the Periodic Table of Elements and Al and / or Si, the MeN being a single layer or a multilayer of two or more sublayers having different elemental compositions, the cemented carbide comprising WC in the form of WC grains within a binder phase, - an uppermost portion of the cemented carbide substrate (5) is present, wherein WC grains are present including an uppermost WC interface with the coating (6), and wherein a binder phase is present including an uppermost binder phase interface with the coating (6), - the WC grains comprising the uppermost WC interface with the coating (6) have an uppermost region adjacent to the coating (6), the uppermost region containing N and one or more of Ti, Cr, Zr, Nb, Mo and V in addition to W and C, the uppermost region being 1.5 to 8 nm, preferably 2 to 6 nm, and most preferably 2 to 4 nm, - the uppermost region of the WC grains adjacent to the coating (6) comprises ≤ 0.6 atomic %, suitably ≤ 0.5 atomic %, preferably ≤ 0.4 atomic %, more preferably ≤ 0.3 atomic % of any rare gas element or combination of rare gas elements.

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 with Al and / or Si.

3. The coated cutting tool (1) according to any one of claims 1 to 2, wherein: The MeN layer is the innermost layer of the coating (6) adjacent to the cemented carbide substrate (5), and the MeN is an alternating sublayer with different elemental compositions (Me1N, Me2N, ... n N, n is a number from 2 to 5, or from 2 to 4, or from 2 to 3), multiple layers of Me1, Me2, ...Me n Each is one or more kinds of Me, wherein Me is one or more kinds of metals of Groups 4 to 6 in the periodic table, or a combination of one or more kinds of metals of Groups 4 to 6 in the periodic table and Al and / or Si.

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

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

6. The coated cutting tool (1) according to any one of claims 4 to 5, wherein: The first content of C in the uppermost region of the WC grains including the uppermost WC interface with the coating (6) is 20 to 60 atomic %, and the second content of C in the uppermost region of the WC grains including the uppermost WC interface with the coating (6) is 0 to 25 atomic %.

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

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

9. The 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 substrate (5) and the coating (6), as measured in a cross section of the cutting tool (1) perpendicular to the surface plane of the cemented carbide substrate (5).

10. The coated cutting tool (1) according to any one of claims 1 to 9, wherein: As measured in a cross section of the cutting tool perpendicular to the surface plane of the cemented carbide substrate (5), 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).

11. The coated cutting tool (1) according to any one of claims 1 to 10, wherein the binding phase has an uppermost region adjacent to the coating (6), and the uppermost region contains N, W and one or more of Ti, Cr, Zr, Nb, Mo and V on the basis of containing a binder metal, and the uppermost region has a thickness of 1 to 5 nm.

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

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

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

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