Surface-coated cutting tool

Abstract

A surface-coated cutting tool, the composition of the lower layer being (Al 1‑x Cr x )N (x is 0.20 to 0.60), the composition of the intermediate layer being (Al 1‑a‑b Cr a Si b )N (a is 0.20 to 0.60, b is 0.01 to 0.20), and having a repeated change in Si concentration with an average interval between the maximum value and the minimum value of 1 to 100 nm. When the average value of the maximum value of the Si concentration is set as Si max , 1.0 < Si max / b ≤ 2.0. When the average value of the minimum value of the Si concentration is set as Si min , 0.0 ≤ Si min / b < 1.0. The composition of the upper layer is (Ti 1‑α‑β Si α W β )N (α is 0.01 to 0.20, β is 0.01 to 0.10), and having a repeated change in W concentration with an average interval between the maximum value and the minimum value of 1 to 100 nm. When the average value of the maximum value of the W concentration is set as W max , 1.0 < W max / β ≤ 2.0. When the average value of the minimum value of the W concentration is set as W min , 0.0 ≤ W min / β < 1.0.

Description

Technical Field

[0001] The present invention relates to a surface-coated cutting tool (hereinafter, sometimes referred to as a coated tool).

[0002] This application claims priority based on Japanese Patent Application No. 2020-59802 filed on March 30, 2020. All the descriptions contained in the Japanese patent application are incorporated herein by reference. Background Art

[0003] In recent years, the performance of cutting devices has been significantly improved. On the other hand, there are strong demands for labor saving, energy saving, and cost reduction in cutting, and accordingly, cutting conditions have become more stringent.

[0004] As a coated tool, there is known a coated tool in which a hard coating layer composed of a composite nitride layer of Al and Cr is formed by arc ion plating on the surface of a tool substrate such as tungsten carbide (hereinafter, represented by WC) based cemented carbide.

[0005] Moreover, many proposals have been made to improve the cutting performance of coated tools.

[0006] For example, Patent Document 1 proposes a coated tool coated with a first coating layer and a second coating layer. The first coating layer is (Al a Cr 100-a-b Si b ) c N d (a and b are atomic percentages, c and d represent atomic ratios, 50 ≤ a ≤ 70, 0 ≤ b < 15, 0.85 ≤ c / d ≤ 1.25), and the second coating layer is (Ti 100-e Si e ) f N g (e is an atomic percentage, f and g represent atomic ratios, 1 ≤ e ≤ 20, 0.85 ≤ f / g ≤ 1.25). When the plane spacing (nm) of the (200) plane in the X-ray diffraction of the first coating layer and the second coating layer is set as d1 and d2 respectively, 0.965 ≤ d1 / d2 ≤ 0.990. This coated tool ensures a reduction in compressive stress and good adhesion in the thick coating layer, and improves wear resistance.

[0007] In addition, Patent Document 2 proposes a coated tool in which the coating layer is composed of a coating layer 1 coated on the tool substrate side and a coating layer 2 coated on the surface side. The composition of the coating layer 1 is (Al a Cr 1-a ) 1-x N x(0.50 ≤ a < 0.70, 0.48 ≤ x ≤ 0.52) means that when the half-value width of the 111 diffraction line in the X-ray diffraction of the coating layer 1 is set to W1 (degrees), 0.7 ≤ W1 ≤ 1.1. When the peak intensity of the 111 diffraction line is set to Ir, the peak intensity of the 200 diffraction line is set to Is, and the peak intensity of the 220 diffraction line is set to It, 0.3 ≤ Is / Ir < 1.0 and 0.3 ≤ It / Ir < 1. The composition of the coating layer 2 is composed of (Ti 1-b Si b ) 1-y N y (0.01 ≤ b ≤ 0.25 and 0.48 ≤ y ≤ 0.52) means that when the half-value width of the 111 diffraction line in the X-ray diffraction of the coating layer 2 is set to W2 (degrees), 0.6 ≤ W2 ≤ 1.1. When the peak intensity of the 111 diffraction line is set to Iu, the peak intensity of the 200 diffraction line is set to Iv, and the peak intensity of the 220 diffraction line is set to Iw, 0.3 ≤ Iv / Iu < 1 and 0.3 ≤ Iw / Iu < 1.0. Both the coating layer 1 and the coating layer 2 form a face-centered cubic structure. When the interplanar spacing (nm) of the 111 diffraction line in the X-ray diffraction is set to a1 and a2 respectively, 0.970 ≤ a1 / a2 ≤ 0.980. This coating tool can ensure the close contact strength between the tool substrate and the coating layer and has excellent wear resistance.

[0008] In addition, in Patent Document 3, a coating tool is proposed, in which the coating layer includes a multilayer film layer formed by alternately laminating two or more layers of a first coating layer and a second coating layer. The first coating layer is a nitride film composed of Al (100-x-y-z) Cr (x) V (y) B (z) (20 ≤ x ≤ 40, 2 ≤ y ≤ 15, 2 ≤ z ≤ 15), and the second coating layer is a nitride film composed of Ti (100-v-w) Cr (v) Si (w) (5 ≤ v ≤ 30, 5 ≤ w ≤ 30). The layer thickness of each layer of the first coating layer and the second coating layer is set to 1 - 20 nm. There is a mixed tissue part where the components of the first coating layer and the second coating layer are mixed. The area of this mixed tissue part is 5 - 80% of the cross-sectional area of the multilayer film layer. This coating tool shows excellent wear resistance in the cutting of high-hardness quenched steel.

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-93085

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-45650

[0011] Patent Document 3: Japanese Patent No. 5087427 Gazette Summary of the Invention

[0012] The present invention has been completed in view of the above circumstances and the above proposals, and its object is to obtain a coated tool that has excellent chipping resistance and defect resistance in the high-load cutting process where a high load acts on the cutting edge, and exhibits excellent wear resistance and fracture resistance during long-term use. Among them, the high-load cutting process is, for example, high-speed and high-feed deep-hole drilling of workpieces such as carbon steel, alloy steel, and stainless steel (for example, machining using a small-diameter drill or a small-diameter long drill).

[0013] The surface-coated cutting tool according to an embodiment of the present invention is as described below.

[0014] 1) It has a tool substrate and a coating layer on the surface of the tool substrate.

[0015] 2) The average layer thickness of the coating layer is 0.5 to 8.0 μm, and the coating layer sequentially has a lower layer, an intermediate layer, and an upper layer from the tool substrate side toward the tool surface.

[0016] 3) The lower layer with an average layer thickness of 0.1 to 4.0 μm is composed of layer A. When the average composition of layer A is represented by the composition formula: (Al 1-x Cr x )N, x is 0.20 to 0.60.

[0017] 4) The intermediate layer with an average layer thickness of 0.1 to 4.0 μm is composed of layer B. When the average composition of layer B is represented by the composition formula: (Al 1-a-b Cr a Si b )N, a is 0.20 to 0.60 and b is 0.01 to 0.20.

[0018] 5) The layer B has a repeated change in the Si concentration with an average interval between adjacent maximum and minimum values of 1 to 100 nm. When the average value of the maximum value of the Si concentration is set as Si max , 1.0 < Si max / b ≤ 2.0, and when the average value of the minimum value of the Si concentration is set as Si min , 0.0 ≤ Si min / b < 1.0.

[0019] 6) The upper layer with an average layer thickness of 0.1 to 4.0 μm is composed of layer C. When the average composition of layer C is represented by the composition formula: (Ti 1-α-β Si α W β)When N represents the average composition of the C layer, α is 0.01 to 0.20 and β is 0.01 to 0.10,

[0020] 7) The C layer has a repeated change in W concentration with an average interval between adjacent maxima and minima of 1 to 100 nm. When the average value of the maxima of the W concentration is set as W max 1.0 < W max / β ≤ 2.0, and when the average value of the minima of the W concentration is set as W min 0.0 ≤ W min / β < 1.0.

[0021] In addition, the surface-coated cutting tool according to the foregoing embodiment may also satisfy one or more of the following (1) to (3).

[0022] (1) The intermediate layer is a D layer, the D layer has an alternating laminated structure of the B layer and the A layer and its average layer thickness is 0.5 to 4.0 μm, and two or more of the B layers are included in the D layer.

[0023] (2) There is an intimate layer with an average layer thickness of 0.1 to 2.0 μm between the intermediate layer and the upper layer. The intimate layer is composed of an E layer. When the composition of the E layer is represented by the composition formula (Al 1-k-l-m-n Ti k Cr l Si m W n )N, k is 0.20 to 0.65, l is 0.10 to 0.35, m is greater than 0.00 and 0.15 or less, n is greater than 0.00 and 0.05 or less. The E layer has a repeated change in Si concentration with an average interval between adjacent maxima and minima of 1 to 100 nm. When the average value of the maxima of the Si concentration is set as Si max(E) 1.0 < Si max(E) / m ≤ 2.0, and when the average value of the minima of the Si concentration is set as Si min(E) 0.0 ≤ Si min(E) / b < 1.0.

[0024] (3) Grains having a rock-salt type cubic crystal structure are included in each layer constituting the coating layer. When the X-ray diffraction peaks obtained from the A layer and the B layer are summed up and obtained, the full width at half maximum of the peak of the 200 diffraction line is 0.2 to 1.0 degrees. When the peak intensity of the 200 diffraction line is set as I AB200 and the peak intensity of the 111 diffraction line is set as I AB111 0.5 < I AB200 / I AB111< 10.0, when the peak intensity of the 200 diffraction line of the C layer is set as I C200 and the peak intensity of the 111 diffraction line is set as I C111 0.5 < I C200 / I C111 < 10.0.

[0025] According to the foregoing, in high-load cutting processes of carbon steel, alloy steel, stainless steel, etc. where high loads act on the cutting edge, excellent chipping resistance, defect resistance, and wear resistance are also exhibited. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a diagram schematically showing a longitudinal section of a coating layer of a surface-coated cutting tool according to an embodiment of the present invention.

[0027] Figure 2 is a diagram schematically showing a repeated change in Si concentration in a longitudinal section of a coating layer of a surface-coated cutting tool according to an embodiment of the present invention.

[0028] Figure 3 is a diagram schematically showing a longitudinal section of a coating layer of a surface-coated cutting tool according to another embodiment of the present invention.

[0029] Figure 4 is a diagram schematically showing a longitudinal section of a coating layer of a surface-coated cutting tool according to still another embodiment of the present invention.

[0030] Figure 5 is a schematic top view of an arc ion plating (AIP) apparatus used for forming a coating layer in an example.

[0031] Figure 6 is Figure 5 a schematic front view of the arc ion plating apparatus.

[0032] Figure 7 is a diagram showing the XRD analysis results of Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present inventors studied the coated tools proposed in Patent Documents 1 to 3 above. As a result, the following problems were recognized: Although no particular problems occur when these coated tools are used for cutting processes under normal conditions for steel or cast iron, when used under severe cutting conditions (high-load cutting processes) where high loads act on the cutting edge, chipping, defects, etc. are likely to occur, and sufficient wear resistance cannot be exhibited, and the service life is reached in a relatively short time. For example, when used as a drill bit (especially a small-diameter drill bit or a long small-diameter drill bit), the cutting force increases due to the generation of welding, chip jamming, etc., and sometimes the drill bit breaks, resulting in the end of the service life.

[0034] Specifically, the present inventors recognized the following problems: Although the hard coating layer formed by laminating a composite nitride layer of (Al, Cr, Si)N layer and (Ti, Si)N layer in the above Patent Document 1 has high hardness, excellent oxidation resistance and wear resistance, when it is provided for cutting processing in which continuous high loads act on the cutting edge such as high-speed high-feed deep-hole drill machining, the chipping resistance and the defect resistance are reduced.

[0035] In addition, the present inventors also recognized the following problem: When the coated tool proposed in the above Patent Document 2 is provided for cutting processing in which continuous high loads act on the cutting edge, the chipping resistance and the defect resistance are also reduced.

[0036] Furthermore, the present inventors recognized the following problem: Although the coated tool having a coating layer formed of an alternating laminated structure of (Al, Cr, V, B)N layer and (Ti, Cr, Si)N layer proposed in the above Patent Document 3 exhibits excellent wear resistance in cutting of high-hardness workpieces, when used under severe cutting conditions where high loads act on the cutting edge, generation of chipping and generation of defects cannot be avoided, and thus the tool life is shortened due to this.

[0037] Therefore, based on these recognitions, the present inventors repeatedly conducted in-depth research, and as a result, obtained the following insights (1) to (2).

[0038] (1) Although in the (Al, Cr, Si)N layer proposed in the above Patent Document 1, Al as a component constituting the layer has the effect of improving high-temperature hardness and heat resistance, Cr has the effect of improving high-temperature strength, and has the effect of improving high-temperature oxidation resistance in a state where Cr and Al coexist, and in addition, Si has the effect of improving heat resistance, but since the Si component increases the lattice distortion of the (Al, Cr, Si)N layer, when high loads act on the cutting edge, the (Al, Cr, Si)N layer does not have sufficient toughness to withstand high loads, and thus chipping and defects are likely to occur.

[0039] (2) In particular, when the coating layer is formed into a laminated structure of (Al, Cr, Si)N layer and other hard layers, in addition to the low toughness of the (Al, Cr, Si)N layer itself, a large distortion caused by lattice mismatch at the laminated interface with other hard layers is generated, and thus the toughness of the entire coating layer is further reduced, and generation of chipping and defects cannot be avoided.

[0040] Therefore, the present inventors have further studied the (Al, Cr, Si)N layer. As a result, by adjusting the composition content of this layer and the distribution state of the components, lattice distortion is less likely to occur, and other hard layers with good adhesion to both the tool substrate and the (Al, Cr, Si)N layer have been found.

[0041] That is, it has been found that by adopting a laminated structure of this layer, a composite nitride layer of Al and Cr (hereinafter sometimes referred to as (Al, Cr)N) and a composite nitride layer of Ti, Si and W (hereinafter sometimes referred to as (Ti, Si, W)N), while improving the adhesion strength required for the coating layer, high toughness of the entire coating layer is achieved, and even under cutting conditions with high loads, a coated tool with excellent chipping resistance, defect resistance, wear resistance and excellent fracture resistance can be obtained.

[0042] Hereinafter, the coated tool according to the embodiment of the present invention will be described in detail.

[0043] In addition, in this specification and the claims, when a numerical range is represented by "L to M" (both L and M are numerical values), the range includes the upper limit value (M) and the lower limit value (L), and the units of the upper limit value (M) and the lower limit value (L) are the same.

[0044] Ⅰ、 Figure 1 The embodiment shown

[0045] Figure 1 Schematically shows a longitudinal section of the coating layer of the surface-coated cutting tool according to an embodiment of the present invention (it is a section perpendicular to the surface when the minute unevenness on the surface of the tool substrate is ignored and treated as a flat surface in a blade or the like. Or, it is a section perpendicular to the axis in an axial tool such as a drill). Therefore, first, the Figure 1 The embodiment shown will be described.

[0046] 1. Coating layer

[0047] In Figure 1 In the embodiment shown, as the coating layer, from the tool substrate 1 side toward the tool surface, there are successively a lower layer 2, an intermediate layer 3 and an upper layer 4, which are respectively composed of a layer A 10, a layer B 11 and a layer C 12. Hereinafter, the description will be made in order.

[0048] The average layer thickness of the coating layer (that is, the total average layer thickness of the lower layer, the intermediate layer and the upper layer) is preferably 0.5 to 8.0 μm. The reason is that when it is less than 0.5 μm, the coating layer cannot exhibit excellent wear resistance during long-term use. On the other hand, when it is greater than 8.0 μm, abnormal damages such as chipping, defect and peeling are likely to occur in the upper layer.

[0049] The average layer thickness of the coating layer is more preferably 1.0 to 6.0 μm.

[0050] (1) Lower layer

[0051] The lower layer is composed of layer A of (Al, Cr)N layer with a specified composition. In this (Al, Cr)N layer, Al improves the high-temperature hardness and heat resistance of the lower layer, Cr improves the high-temperature strength and lubricity of the lower layer, and the coexistence of Al and Cr improves the oxidation resistance and wear resistance of the lower layer respectively.

[0052] When the average composition of layer A is represented by the compositional formula: (Al 1-x Cr x )N, it is preferred that the x is 0.20 to 0.60.

[0053] The reason is that when x is less than 0.20, the chipping resistance of the coating layer deteriorates due to the reduction of the high-temperature strength of the lower layer, and since grains with a hexagonal crystal structure appear due to the relatively increased Al content ratio, the hardness of the lower layer decreases and the wear resistance of the coating layer also decreases. On the other hand, when x is greater than 0.60, the lower layer cannot ensure sufficient high-temperature hardness and heat resistance due to the relatively decreased Al content ratio, and the wear resistance of the coating layer decreases.

[0054] A more preferred range of the x value is 0.25 to 0.50.

[0055] In addition, the average layer thickness of layer A as the lower layer is preferably 0.1 to 4.0 μm. The reason is as follows.

[0056] When the average layer thickness of layer A is less than 0.1 μm, sufficient adhesion force with the tool substrate cannot be ensured. On the other hand, when it is greater than 4.0 μm, the distortion in layer A becomes large, and abnormal damages such as chipping and peeling are likely to occur between layer A and the tool substrate, so that the function as an adhesion layer brought by layer A cannot be exerted. The average layer thickness is more preferably 0.1 to 2.0 μm.

[0057] In addition, according to an example of the manufacturing method described later, although it is manufactured to have a ratio of (Al, Cr) to N of 1:1, there are sometimes inevitable (unintentional) cases where it is not 1:1. The same situation exists for other composite nitrides described below.

[0058] (2) Intermediate layer

[0059] The intermediate layer is composed of layer B of (Al, Cr, Si)N with a specified composition. This (Al, Cr, Si)N, like (Al, Cr)N, Cr improves the high-temperature strength and lubricity of the intermediate layer, and also improves the chipping resistance. Moreover, the coexistence of Cr and Al improves the high-temperature oxidation resistance and wear resistance of the intermediate layer.

[0060] Furthermore, although Si has the effect of improving heat resistance and heat plastic deformation resistance, it also increases the lattice distortion of the intermediate layer, resulting in a decrease in the chipping resistance of the intermediate layer. Therefore, repeated changes in the concentration described below are given.

[0061] The average thickness of the intermediate layer composed of the B layer is preferably 0.1 to 4.0 μm. The reason is that when the average thickness is less than 0.1 μm, the coating layer cannot fully exert wear resistance for a long time, and on the other hand, when it is greater than 4.0 μm, the coating layer is prone to abnormal damage such as chipping, defect, and peeling. In addition, the average thickness of the intermediate layer composed of the B layer is more preferably 0.1 to 2.0 μm.

[0062] In the composition formula: (Al 1-a-b Cr a Si b )When N represents the average composition of the B layer, a is preferably 0.20 to 0.60, and b is preferably 0.01 to 0.20.

[0063] The reasons are as follows.

[0064] When the value of a is less than 0.20, the high temperature strength of the B layer decreases, resulting in the deterioration of the chipping resistance of the coating layer, and due to the relative increase in the Al content, hexagonal crystal grains appear in the B layer, thereby reducing its hardness and the wear resistance of the coating layer. On the other hand, when the value of a is greater than 0.60, the B layer cannot ensure sufficient high temperature hardness and heat resistance due to the relative decrease in the Al content, and the wear resistance of the coating layer will decrease. The more preferred range of the value of a is 0.25 to 0.50.

[0065] When the value of b is less than 0.01, the effect of improving the heat resistance and heat plastic deformation resistance of the B layer will be reduced. On the other hand, when the value of b is greater than 0.20, the effect of improving the wear resistance will be reduced. The lattice distortion of the B layer will increase, which will reduce the toughness of the B layer itself. As a result, the chipping resistance and defect resistance of the coating layer under high-load cutting conditions will be reduced. The more preferred range of the b value is 0.01 to 0.15.

[0066] Here, in order to relax the lattice distortion of the B layer and suppress the reduction in the chipping resistance and defect resistance of the cladding layer, a structure having a repeated change in Si concentration is formed in the present embodiment.

[0067] That is, in order to more effectively reduce lattice distortion, regarding the Si concentration, it is preferable to have a repeated change in the Si concentration with an average value of the intervals between adjacent maximum and minimum values (i.e., the average interval in the direction perpendicular to the surface of the tool substrate (layer thickness direction: described in "III. Measurement Method" below)) of 1 to 100 nm. It is inferred that through this repeated change, the sharp change in Si content between layer A and layer B is suppressed, lattice distortion is more effectively reduced, and as a result, the adhesion between the two layers is improved, the generation of peeling of the coating layer, etc. is prevented, and the chipping resistance and defect resistance are improved.

[0068] Figure 2 is a diagram schematically showing an example of the repeated change in Si concentration by setting the vertical axis as the Si concentration [Si] and the horizontal axis as the position X in the direction perpendicular to the surface of the tool substrate. In Figure 2 the maximum value and the minimum value are respectively the same value, and the intervals between adjacent maximum and minimum values are also the same. As long as the repeated change in Si concentration as described in this specification and the claims means that the Si concentration changes in a manner of alternately taking maximum and minimum values, the maximum value and the minimum value can be respectively the same value or different values, and the interval D between adjacent maximum and minimum values can be the same or different.

[0069] Here, regarding the Si concentration, the average interval between adjacent maximum and minimum values is set to 1 to 100 nm. The reason is that when the average interval is less than 1 nm, the Si content changes sharply, so the lattice distortion locally increases and the chipping resistance of the coating layer decreases. On the other hand, when the average interval is greater than 100 nm, the Si content increases, that is, the region with large lattice distortion becomes wider, so chipping is likely to occur starting from this region and the chipping resistance of the coating layer decreases. A more preferable range for the average interval of the repeated change is 5 to 50 nm.

[0070] In addition, preferably, when the average value of the maximum value of the concentration of the Si component is set as Si max 1.0 < Si max / b ≤ 2.0. In addition, when the average value of the minimum value of the concentration of the Si component is set as Si min 0.0 ≤ Si min / b < 1.0. Here, b is the average composition b of Si in the composition formula of layer B.

[0071] As described above, the reason for defining the ratio Si max / b of the average value of the maximum value of the concentration of the Si component to b and the ratio Si min / b of the average value of the minimum value to b is that when Si max / b is greater than 1.0, and Si minWhen / b is less than 1.0, although a reduction in lattice distortion caused by repeated changes in Si concentration can be obtained, in the case of Si max When / b is greater than 2.0, the range of compositional change becomes larger, resulting in a sharp change in Si composition, and thus the chipping resistance of the coating layer will decrease.

[0072] Si max / b and Si min A more preferred range of / b is 1.2 < Si max / b ≤ 2.0, 0.0 ≤ Si min / b < 0.8.

[0073] Here, the average interval between the position of the maximum value of Si given in the B layer with repeated changes in Si concentration and the position of the adjacent minimum value is obtained by the following method: In the longitudinal section of the tool substrate of the B layer, the Si content ratio is measured in the direction perpendicular to the surface of the tool substrate (layer thickness direction: described in "III. Measurement Method" below), and known measurement noise removal is performed to make it graphical.

[0074] That is, as Figure 2 shown, a straight line m is drawn across the curve representing the repeated changes in Si concentration. This straight line m is drawn in such a way that the area of the region surrounded by the curve is equal on the upper and lower sides of the straight line m. Then, for each region where the straight line m crosses the curve representing the repeated changes in Si concentration, the maximum or minimum value of the Si composition concentration is obtained, and the interval between the two is measured. By taking the average of the measured values at multiple locations, the average interval of the repeated changes in Si concentration in the B layer is obtained.

[0075] In addition, by taking the average of the measured values of the maximum value of the Si composition concentration and the minimum value of the Si composition concentration obtained at multiple locations, the average value Si max of the maximum value of Si concentration and the average value Si min of the minimum value of Si concentration are calculated.

[0076] (3) Upper layer

[0077] The upper layer is composed of a C layer of (Ti, Si, W)N as a specified composition.

[0078] This upper layer has Ti as the main component. In addition to improving oxidation resistance and heat-resistant plastic deformation properties by containing Si components, it further improves high-temperature strength by containing W components, thereby improving the wear resistance of the coating layer.

[0079] The average layer thickness of the upper layer is preferably 0.1 to 4.0 μm. The reason for setting the average layer thickness within this range is that, for example, under high-load cutting conditions, the chipping resistance, defect resistance, and wear resistance of the coating layer can be further improved. A more preferred range for the average layer thickness is 0.1 to 2.0 μm.

[0080] When the average composition of the C layer is represented by the compositional formula: (Ti 1-α-β Si α W β )N, α is preferably 0.01 to 0.20, and β is preferably 0.01 to 0.10.

[0081] The reason for setting α within this range is that when it is less than 0.01, the improvement in the oxidation resistance and heat-resistant plastic deformation of the C layer is reduced. On the other hand, when α is greater than 0.20, the lattice distortion increases, and thus the C layer is prone to self-destruction under high-load cutting conditions.

[0082] In addition, the reason for setting β within this range is that when it is less than 0.01, the effect of increasing the strength at high temperatures brought about by the C layer is reduced. On the other hand, when β is greater than 0.10, the lattice distortion increases, and thus the chipping resistance of the C layer during high-load cutting is reduced.

[0083] Furthermore, the W concentration has a repeated variation with an average interval between adjacent maximum and minimum values of 1 to 100 nm. When the average value of the maximum value of the W concentration is set as W max it is preferably 1.0 < W max / β ≤ 2.0, and when the average value of the minimum value of the W concentration is set as W min it is preferably 0.0 ≤ W min / β < 1.0. Here, β is the average composition β of W in the compositional formula of the C layer.

[0084] Here, the reason for the preferred average interval between adjacent maximum and minimum values of 1 to 100 nm is that when the average interval is less than 1 nm, the W content changes sharply. Therefore, in the C layer, the lattice distortion locally increases, and the chipping resistance of the coating layer is reduced. On the other hand, when it is greater than 100 nm, the W content increases, that is, the region with large lattice distortion in the upper layer becomes wider. Therefore, chipping is likely to occur starting from this region, and the chipping resistance of the coating layer is reduced. A more preferred range for the average interval of the repeated variation is 5 to 50 nm.

[0085] In addition, the reason for setting the ratio of the average value of the maximum value of the W concentration to β, W max / β, and the ratio of the average value of the minimum value of the W concentration to β, W min / β, within the above ranges is that when W max / β is greater than 1.0, and W minWhen W / β is less than 1.0, although it is possible to reduce the lattice distortion of the C layer caused by the compositional repetition variation, in W max When W / β is greater than 2.0, the compositional variation range becomes larger, resulting in a sharp change in the W composition, and thus the chipping resistance of the coating layer will decrease. W max W / β and W min A more preferred range of W / β is 1.2 < W max / β ≤ 2.0, 0.0 ≤ W min / β < 0.8.

[0086] In addition, for the repetitive variation of the W concentration, its average interval, W max and W min are determined, which is the same as the repetitive variation of the Si concentration described with reference to Figure 2 That is, in Figure 2 , just replace Si with W.

[0087] (4) Grains of the rock-salt type cubic crystal structure (NaCl-type face-centered cubic structure)

[0088] The grains constituting the A layer, B layer, and C layer are preferably of the NaCl-type face-centered cubic structure. In addition, in these layers, there may be an inevitable (unintentional) amount of grains having a crystal structure other than the NaCl-type face-centered cubic structure in industrial production.

[0089] (5) XRD pattern

[0090] In addition, for the layer summarizing the A layer and B layer, the full width at half maximum of the peak of the 200 diffraction line obtained by X-ray diffraction of the grains of the rock-salt type cubic crystal structure constituting each layer is 0.2 to 1.0 degrees. When the peak intensity of the 200 diffraction line is set as I AB200 , and the peak intensity of the 111 diffraction line is set as I AB111 , 0.5 < I AB200 / I AB111 < 10.0. In addition, when the peak intensity of the 200 diffraction line of the C layer obtained by X-ray diffraction of the C layer is set as I C200 , and the peak intensity of the 111 diffraction line is set as I C111 , it is more preferably 0.5 < I C200 / I C111 < 10.0.

[0091] A further preferred range is 0.5 < I AB200 / I AB111 < 5.0, 0.5 < I C200 / I C111 < 5.0.

[0092] The reason is uncertain, but consider the following.

[0093] It is speculated that if the intensity I of the X-ray diffraction peak AB200 has a full width at half maximum of less than 0.2 degrees, then due to the coarsening of the crystal grains, cracks are likely to propagate through the grain boundaries, resulting in a decrease in chipping resistance. On the other hand, if it is greater than 1.0 degree, then due to the refinement of the crystal, sufficient crystallinity cannot be maintained, resulting in a decrease in wear resistance. In addition, it is speculated that by setting the full width at half maximum within the above range, the difference in lattice constants of the crystals constituting the A layer and the B layer becomes smaller, and the distortion caused by the lattice mismatch at the stacking interface between the A layer and the B layer decreases, so the chipping resistance is improved.

[0094] It is speculated that if I AB200 / I AB111 is 0.5 or less, then due to the strong orientation of the (111) plane as the closest-packed plane, the chipping resistance decreases. On the other hand, if it is 10.0 or more, then due to the extremely strong orientation of the (200) plane, the wear resistance decreases.

[0095] Moreover, it is speculated that if I C200 / I C111 is 0.5 or less, then due to the strong orientation of the (111) plane as the closest-packed plane, the chipping resistance decreases. On the other hand, if it is 10.0 or more, then due to the extremely strong orientation of the (200) plane, the wear resistance decreases.

[0096] Here, the so-called summing up the X-ray diffraction peaks of the A layer and the B layer means that when performing X-ray diffraction on the A layer and the B layer, the X-ray diffraction peaks are obtained by measuring in a state where the A layer and the B layer are stacked, rather than in the state of a single A layer or a single B layer.

[0097] 2. Tool substrate

[0098] (1) Material

[0099] If the material is a material of a conventionally well-known tool substrate, any material can be used as long as it does not prevent the achievement of the above object. If an example is given, it is preferably any one of cemented carbide (WC-based cemented carbide, an alloy of a substance obtained by adding carbonitrides such as Ti, Ta, Nb, etc. in addition to WC, Co, etc.), cermet (ceramics mainly composed of TiC, TiN, TiCN, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, alumina, etc.), cBN sintered body or diamond sintered body.

[0100] (2) Shape

[0101] The shape of the tool substrate is not particularly limited as long as it is a shape used as a cutting tool, and examples thereof can be the shape of a cutting insert, the shape of a drill bit.

[0102] 3. Manufacturing Method

[0103] Regarding the manufacturing method of the present embodiment, for example, a film forming method using the PVD method can be shown as follows.

[0104] (1) Lower Layer

[0105] For example, use Figure 5 and Figure 6 The arc ion plating (AIP) apparatus shown, and in a nitrogen atmosphere, the tool substrate 26 is mounted on the rotating table 25, an arc discharge is generated between the Al-Cr alloy target 23 and the anode electrode 20, and a lower layer composed of layer A with a specified average layer thickness is formed on the surface of the rotating tool substrate.

[0106] (2) Intermediate Layer

[0107] For example, by simultaneously evaporating from the Al-Cr-Si alloy target 22 and the Al-Cr alloy target 23 onto the tool substrate 26 having a lower layer formed on its surface on the rotating table 25 in the above-mentioned arc ion plating apparatus, it is possible to form a repeated change in the Si concentration in layer B constituting the intermediate layer.

[0108] Here, even in the case of using only the Al-Cr-Si alloy target as a single target, by appropriately setting film forming conditions such as the rotation period of the rotating table, the nitrogen pressure, the bias voltage, and the temperature inside the apparatus during arc discharge, a repeated change in the Si concentration can be formed, and thus the coating layer of the present embodiment can also be formed.

[0109] Since the repeated change in the Si concentration formed using a single target is formed by the element distribution inside the apparatus during film formation, for example, when the nitrogen pressure is increased, the difference in the mean free path of each element becomes larger, and it is easy to form a repeated change in the Si concentration. However, when the temperature of the tool substrate increases due to an increase in the bias voltage or the temperature inside the apparatus, since atomic diffusion easily occurs in the coating layer, it is difficult to form a repeated change in the Si concentration. In addition, in the case of using a single target, there are limitations in controlling the characteristics of the coating layer such as the repeated change in the Si concentration and crystallinity.

[0110] Therefore, by simultaneously evaporating from the Al-Cr-Si alloy target and the Al-Cr alloy target, it is possible to actively form a repeated change in the Si concentration while easily controlling characteristics such as crystallinity, and more reliably form the coating layer of the present embodiment.

[0111] In addition, by adjusting, for example, the arc current, the bias voltage, the reaction gas pressure, and the film forming temperature in the arc ion plating conditions for forming layer A and layer B, it is possible to control the I AB200 / I AB111 value within a specified range.

[0112] (3) Upper layer

[0113] For example, by pre-setting two Ti-Si-W alloy targets 21 with different compositions and simultaneously vapor-depositing on a rotating table 25 in the aforementioned arc ion plating apparatus on a tool substrate 26 having a lower layer and an intermediate layer formed on its surface, it is possible to form a repeated change in the W concentration in the C layer. Of course, as described in the formation of the repeated change in the Si concentration in the B layer, it is also possible to use only a Ti-Si-W alloy target with the same composition and form a repeated change in the W concentration by adjusting the film-forming conditions.

[0114] In addition, by adjusting, for example, the arc current, bias voltage, reaction gas pressure, and film-forming temperature in the arc ion plating conditions for forming the C layer, it is possible to control the I C200 / I C111 value within a specified range.

[0115] II、 Figure 3 The embodiment shown

[0116] Figure 3 Schematically shows a longitudinal section of the coating layer of a surface-coated cutting tool according to another embodiment of the present invention. Then, Figure 3 The embodiment shown will be described.

[0117] In addition, parts that are repetitive in the description of the embodiment shown Figure 1 will not be described in detail.

[0118] 1. Coating layer

[0119] In Figure 3 the embodiment shown, as the coating layer, from the tool substrate 1 side toward the tool surface, there are successively a lower layer 2, an intermediate layer 3', and an upper layer 4. The fact that the lower layer 2 is composed of the A layer 10 and the upper layer 4 is composed of the C layer 12 is the same as Figure 1 the embodiment shown. In this embodiment, the intermediate layer 3' is composed of the D layer 13 which is an alternating laminated structure of the A layer 10 and the B layer 11. In addition, the number of laminations of the A layer 10 and the B layer 11 is not limited to Figure 3 the number of laminations shown.

[0120] (1) Intermediate layer

[0121] In this embodiment, the intermediate layer is composed of a D layer which is an alternating stacked structure of an A layer and a B layer. The average layer thickness of the D layer is preferably 0.5 to 4.0 μm. The reason is that when the average layer thickness is less than 0.5, the coating layer cannot fully exert wear resistance for a long time. On the other hand, when it is greater than 4.0 μm, the coating layer is prone to abnormal damage such as chipping, defect, and peeling. In addition, in the D layer, the average layer thickness of the A layer and the B layer are preferably 0.1 to 1.5 μm, respectively.

[0122] More preferably, both the layer closest to the tool base body side (closest to the lower layer side) and the layer closest to the tool surface side (closest to the upper layer side) of the D layer are B layers.

[0123] The reason is that by providing layer B as the layer closest to the tool substrate, the bonding strength between the lower layer (layer A) and the middle layer (layer D) can be further ensured, and by forming layer B as the layer closest to the tool surface, the bonding strength with layer C as the upper layer can be improved, thereby further ensuring the chipping resistance of the coating layer during high-load cutting.

[0124] (2) Number of layers

[0125] Regarding the number of layers of A and B in layer D, there is no particular restriction if the average layer thicknesses of layer A and layer B in layer D are 0.1 to 1.5 μm respectively, and the thickness of the intermediate layer is 0.5 to 4.0 μm. It is more preferably 2 to 5 layers respectively, for example, two layers of layer A and three layers of layer B.

[0126] (3) Crystal grains and XRD patterns of rock salt cubic crystal structure

[0127] The crystal grains and XRD patterns of the rock salt cubic structure are similar to those in Figure 1 The same is true as described in the description of the illustrated embodiment.

[0128] 2. Tool base

[0129] The material and shape of the tool base Figure 1 The same is true as described in the description of the illustrated embodiment.

[0130] 3. Manufacturing method

[0131] Only the method for producing the D layer constituting the intermediate layer will be described.

[0132] For example, by Figure 5 and Figure 6On the rotating table 25 in the aforementioned arc ion plating apparatus shown, on a tool substrate 26 having a lower layer formed on its surface, simultaneous evaporation is performed from an Al—Cr—Si alloy target 22 and an Al—Cr alloy target 23, whereby a repeated change in the concentration of Si component is formed in the B layer that constitutes the intermediate layer of the alternately laminated structure. Next, by performing evaporation from the Al—Cr alloy target 23, an A layer having a prescribed layer thickness is formed. By repeating such steps, it is possible to form the D layer that constitutes the intermediate layer formed of an alternately laminated structure of the B layer and the A layer, and at the same time, a repeated change in Si concentration is formed in the B layer.

[0133] III、 Figure 4 The embodiment shown

[0134] Figure 4 Schematically shows a longitudinal cross section of a coating layer of a surface-coated cutting tool according to still another embodiment of the present invention. Then, for Figure 4 The embodiment shown is described.

[0135] In addition, parts that are repetitive with the description of Figure 1 and Figure 3 the embodiment shown are not described in detail.

[0136] 1. Coating layer

[0137] As Figure 4 shown, in addition to the lower layer 2, the intermediate layer 3', and the upper layer 4, the coating layer further has an adhesion layer 5 between the intermediate layer 3' and the upper layer 4. In addition, the number of laminated layers that constitute the intermediate layer 3' is not limited to the number of laminated layers shown in the figure.

[0138] (1) Adhesion layer

[0139] In the present embodiment, the adhesion layer is constituted by an E layer between the intermediate layer (D layer) and the upper layer (C layer). This E layer is provided, for example, to improve the adhesion between the D layer and the C layer when there is a difference between the value b of the Si content ratio of the B layer that constitutes the D layer and the value α of the Si content ratio of the C layer.

[0140] The average layer thickness of the E layer is preferably 0.1 to 2.0 μm. The reason is that when the average layer thickness of the E layer is less than 0.1 μm, the above-described adhesion cannot be sufficiently improved, while when it is greater than 2.0 μm, the lattice distortion in the E layer becomes large, and thus the above-described adhesion is reduced.

[0141] In the compositional formula: (Al 1-k-l-m-n Ti k Cr l Si m W n)When N represents the composition of the average composition of the E layer, it is preferable that k is 0.20 to 0.65, l is 0.10 to 0.35, m is greater than 0.00 and 0.15 or less, and n is greater than 0.00 and 0.05 or less.

[0142] The reason for determining the average composition is as described below.

[0143] Regarding Ti, which has the effect of improving the high-temperature hardness and high-temperature strength of the E layer, when the content ratio is less than 0.20, the high-temperature strength cannot be obtained sufficiently, and since the Al content ratio becomes high, grains having a hexagonal crystal structure are formed in the E layer, suppressing the effect of improving the adhesion of the E layer. On the other hand, when it is greater than 0.65, the content ratio of other components becomes small, and sufficient wear resistance of the coating layer cannot be obtained.

[0144] Regarding Cr, which has the effect of improving the high-temperature strength and lubricity of the E layer, when the content ratio is less than 0.10, the lubricity cannot be obtained sufficiently. On the other hand, when it is greater than 0.35, the content ratio of other components becomes small, and sufficient wear resistance of the coating layer cannot be obtained.

[0145] Regarding Si, which has the effect of improving the oxidation resistance and heat-resistant plastic deformation property of the E layer, when it is not contained (0.00 or less), the oxidation resistance of the E layer cannot be obtained, and the adhesion with the B layer and the C layer cannot be obtained sufficiently, so the adhesion with these layers is reduced. On the other hand, when the content ratio is greater than 0.15, the lattice distortion in the E layer becomes large, and thus the adhesion is reduced.

[0146] Regarding W, which has the effect of improving the high-temperature strength and wear resistance of the E layer, when it is not contained (0.00 or less), the high-temperature strength of the E layer is not sufficient, and the adhesion with the C layer cannot be obtained sufficiently, so the adhesion with the C layer is reduced. On the other hand, when the content ratio is greater than 0.05, the lattice distortion in the E layer becomes large, and thus the adhesion is reduced.

[0147] In addition, it is preferable that there is a repeated change in the Si concentration having an interval between a maximum value and a minimum value adjacent to each other in the adhesion layer of 1 to 100 nm. When the average value of the maximum values of the Si concentration is set as Si max(E) 1.0 < Si max(E) / m ≤ 2.0, and when the average value of the minimum values of the Si concentration is set as Si min(E) 0.0 ≤ Si min(E) / m < 1.0.

[0148] Here, the repeated change in the Si concentration is the same as the case described in Figure 2 is the same.

[0149] Here, the reason why the average interval between adjacent maximum and minimum values is preferably 1 to 100 nm is that when the average interval is less than 1 nm, the Si composition changes sharply, so the coating layer is likely to produce chipping, and the effect of improving the bonding strength between the C layer and the D layer cannot be fully obtained in the E layer. On the other hand, when it is greater than 100 nm, the Si content increases, that is, the region with large lattice distortion becomes wider, so chipping is likely to occur starting from this region, and the bonding strength cannot be fully improved. The more preferable range of the average interval of the repeated change is 5 to 50 nm.

[0150] In addition, the reason for setting the ratio of the average value of the maximum value of the Si concentration to m, Si max(E) / m and the ratio of the average value of the minimum value of the Si concentration to m, Si min(E) / m within the aforementioned range is that although repeated changes in the Si max(E) / m greater than 1.0 and Si min(E) / m less than 1.0 result in repeated changes in the Si concentration, when the Si max(E) / m is greater than 2.0, the change in the composition becomes large, resulting in a sharp change in the Si composition, and thus the chipping resistance decreases.

[0151] (3) Grains of rock-salt type cubic crystal structure

[0152] In the E layer constituting the bonding layer, the crystal structure of the grains is also preferably the face-centered cubic structure of the NaCl type. In addition, similar to the A layer, B layer, and D layer, in these layers, there may be an inevitable (unintentional) amount of grains having a crystal structure other than the face-centered cubic structure of the NaCl type.

[0153] (4) XRD pattern

[0154] It is the same as described in the description of the embodiment shown in Figure 1 .

[0155] 2. Tool substrate

[0156] The material and shape of the tool substrate are the same as described in the description of the embodiment shown in Figure 1 .

[0157] 3. Manufacturing method

[0158] Only the manufacturing method of the E layer constituting the bonding layer will be described.

[0159] For example, by using Figure 5 and Figure 6On the rotating table 25 in the aforementioned arc ion plating apparatus shown, on a tool substrate 26 having a lower layer and an intermediate layer formed on its surface, simultaneous evaporation is performed from an Al-Cr-Si alloy target 22 and a Ti-Si-W alloy target 21, whereby an E layer as an adhesion layer can be evaporated and formed. In this case, repeated variations in the concentration of the Si component are formed in the E layer.

[0160] In addition, in Figure 4 the embodiment shown, the intermediate layer uses a D layer which is an alternating laminated structure of an A layer and a B layer, and the intermediate layer may also be composed only of the B layer.

[0161] III. Measurement Method

[0162] 1. Measurement of average composition, interfaces of each layer, and average layer thickness of each layer

[0163] By performing cross-section measurement using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS), the longitudinal section is measured and averaged, thereby obtaining the concentration of the components constituting each layer.

[0164] In the claims and the description of this specification, the surface of the tool substrate refers to the reference line of the interface roughness between the tool substrate and the coating layer in the observation image of the longitudinal section. That is, when the tool substrate has a planar surface such as a blade, by performing element mapping using EDS in the longitudinal section, performing known image processing on the obtained element mapping, the interface between the lower layer and the tool substrate is determined. For the roughness curve of the interface between the lower layer and the tool substrate thus obtained, the average line is obtained arithmetically and used as the surface of the tool substrate. And the direction perpendicular to this average line is set as the direction perpendicular to the tool substrate (layer thickness direction).

[0165] In addition, in the case where the tool substrate has a curved surface such as a drill bit, if the tool diameter is large enough relative to the layer thickness of the coating layer, the interface between the coating layer and the tool substrate in the measurement region is substantially planar. Therefore, the surface of the tool substrate can also be determined by the same method. That is, for example, in the case of a drill bit, elemental mapping using EDS is performed in the longitudinal section of the coating layer in a cross section perpendicular to the axial direction. By performing known image processing on the obtained elemental mapping, the interface between the lower layer (layer A) and the tool substrate is determined. For the roughness curve of the interface between the lower layer (layer A) and the tool substrate thus obtained, the average line is obtained arithmetically and used as the surface of the tool substrate. And the direction perpendicular to this average line is set as the direction perpendicular to the tool substrate (layer thickness direction).

[0166] In addition, the measurement region in the longitudinal section is set to include all thickness regions of the coating layer. In view of the total layer thickness of the coating layer, the measurement accuracy of the layer thickness, etc., it is preferable to perform observation and measurement of multiple fields of view (for example, three fields of view) in a field of view of about 10 μm × 10 μm.

[0167] In addition, since there are repeated changes in the Si concentration or W concentration in the B layer, C layer, and E layer, the Si concentration or W concentration in each layer is measured along the direction perpendicular to the surface of the tool substrate (layer thickness direction) by multiple analysis lines (for example, five lines). The positions where the Si concentration and W concentration appear and are each 1 atomic% (that is, the positions where b = 0.01 or β = 0.01) are determined as the interfaces with the adjacent layers. The layer thicknesses are obtained separately for multiple lines, and the average value of the obtained layer thicknesses is set as the average layer thickness. Since there is only one layer for the C layer and E layer, the average value of the layer thicknesses measured for this layer by multiple analysis lines is set as the average layer thickness.

[0168] 2. Confirmation of grains having a face-centered cubic structure of the NaCl type

[0169] The crystal structures of the A layer, B layer, C layer, and E layer are identified by electron beam diffraction of a transmission electron microscope (TEM), and it is confirmed that these crystal structures are face-centered cubic structures of the NaCl type.

[0170] Examples

[0171] Hereinafter, examples will be listed to illustrate the present invention, but the present invention is not limited to the examples.

[0172] <Example A>

[0173] An example corresponding to an embodiment of a coated tool having a coating layer as shown Figure 1 is described, where the coating layer has a lower layer (layer A), an intermediate layer (layer B), and an upper layer (layer C).

[0174] A drill bit substrate was prepared as a tool substrate.

[0175] 1. Fabrication of the drill bit substrate:

[0176] As raw material powders, Co powder, VC powder, TaC powder, NbC powder, Cr3C2 powder, and WC powder, each having an average particle size of 0.5 - 5 μm, were prepared. These raw material powders were compounded according to the compounding composition shown in Table 1, and wax was further added. They were wet-mixed using a ball mill for 72 hours, and after drying under reduced pressure, they were compacted at a pressure of 100 MPa.

[0177] After sintering these green compacts, a round bar sintered body with a diameter of 3 mm for forming the tool substrate was formed, and further, WC-based cemented carbide drill bit substrates 1 - 3 having a double-edge shape with a diameter × length dimension of 2 mm × 45 mm for the groove forming part and a helix angle of 30 degrees were manufactured by grinding.

[0178] [Table 1]

[0179]

[0180] (Note) "-" indicates not contained.

[0181] Film forming process:

[0182] When forming a film on the above-mentioned drill bit substrates 1 - 3 using the Figure 5 and Figure 6 shown arc ion plating apparatus, the following treatments (a) - (e) are carried out.

[0183] Regarding the Figure 5 and Figure 6 shown arc ion plating apparatus, in addition to the aforementioned rotary table 25, targets 21, 22, 23, it also has an anode electrode 20, a heater 24, a reaction gas inlet 27, an exhaust port 28, an arc power supply 29, a bias power supply 30, etc.

[0184] (a) In a state where the drill bit substrates 1 - 3 are ultrasonically cleaned in acetone and dried, they are mounted along the outer peripheral part at a position radially away from the central axis of the rotary table inside the arc ion plating apparatus by a specified distance.

[0185] (b) While evacuating the inside of the apparatus and maintaining a vacuum of 10 -2 Pa or less, after heating the inside of the apparatus to 500 °C using a heater, an Ar gas atmosphere of 0.2 Pa is set, and a DC bias voltage of -200 V is applied to the tool substrate rotating on the rotary table, thereby bombarding the surface of the drill bit substrate with argon ions for 20 minutes.

[0186] (c) Introduce nitrogen gas into the device as a reaction gas to form a specified N2 atmosphere within the range of 2.0 to 8.0 Pa shown in Table 2, and also maintain the temperature inside the device shown in Table 2. Additionally, control the rotation speed of the turntable shown in Table 2 in the same manner. Apply a specified DC bias voltage within the range of -30 to -60 V shown in Table 2 to the drill bit substrate rotating on the turntable, and cause a specified current within the range of 100 to 150 A shown in Table 2 to flow between the Al-Cr alloy target and the anode electrode to generate arc discharge, thereby depositing and forming a lower layer composed of layer A with a specified layer thickness.

[0187] (d) By adjusting the DC bias voltage applied to the drill bit substrate to a specified value within the range of -25 to -60 V shown in the deposition condition column of layer B in Table 2, and causing a specified current within the range of 100 to 150 A shown in Table 2 to flow between the Al-Cr alloy target and the anode electrode to generate arc discharge, while also causing a specified current within the range of 150 to 180 A shown in Table 2 to flow between the Al-Cr-Si alloy target and the anode electrode to generate arc discharge, thereby depositing and forming an intermediate layer on the surface of the previously formed lower layer (layer A). This intermediate layer is composed of layer B with a specified layer thickness formed by co-deposition with a repetitive change in Si concentration.

[0188] (e) Introduce nitrogen gas into the device as a reaction gas to form a specified reaction atmosphere within the range of 2.0 to 8.0 Pa shown in Table 3, and also maintain the temperature inside the device shown in Table 3. Additionally, control the rotation speed of the turntable shown in Table 3 in the same manner. Apply a specified DC bias voltage within the range of -25 to -70 V shown in Table 3 to the drill bit substrate rotating on the turntable, and cause a specified current within the range of 100 to 180 A shown in Table 3 to flow between the Ti-Si-W alloy target and the anode electrode to generate arc discharge, thereby depositing and forming an upper layer. This upper layer is composed of layer C with a specified layer thickness formed with a repetitive change in W concentration.

[0189] As shown in Table 3, for Examples 1 to 5 and Example 7, layer C is formed with a repetitive change in W concentration through the co-deposition of two Ti-Si-W alloy targets. For Example 6, layer C is formed with a repetitive change in W concentration through the deposition of one Ti-Si-W alloy target and the control of film-forming parameters.

[0190] Through the aforementioned processes (a) to (e), Examples 1 to 7 with a coating layer were fabricated. This coating layer is composed of the lower layer (layer A) and the intermediate layer (layer B) shown in Table 6 and the upper layer (layer C) shown in Table 7.

[0191] In the vapor deposition film-forming process of the above (a) to (d), particularly by adjusting the arc current value, the nitrogen partial pressure as the reaction gas, the bias voltage, the film-forming temperature, etc. in the vapor deposition conditions of the A layer and the B layer, the half-peak full width of the grains of the rock salt-type cubic crystal structure of the intermediate layer generated by the simultaneous vapor deposition of the Al-Cr alloy target and the Al-Cr-Si alloy target, and the value of I AB200 / I AB111 are controlled. AB200 of the AB200 / AB111 value.

[0192] For comparison, in the same manner as in Example 1, under Conditions 11 to 16 shown in Tables 4 and 5, a coating layer composed of a lower layer (A layer), an intermediate layer (B layer), and an upper layer (C layer) was vapor-deposited on the drill bit substrates 1 to 3, thereby producing Comparative Examples 1 to 6 shown in Tables 8 and 9.

[0193] In addition, since it is formed by a single Al-Cr-Si alloy target, the intermediate layer in Comparative Examples 1 to 5 did not form a repeated change in Si concentration as shown in Table 8, and the Si content in the layer thickness direction of the B layer was substantially uniform.

[0194] That is, Comparative Examples 1 to 5 are different from the layer structure of the intermediate layer (B layer) of the example in this regard. In addition, regarding the C layer in Comparative Example 1 and Comparative Example 6, the W content in the layer thickness direction of the C layer was also substantially uniform, and no repeated change in W concentration was formed. The C layer of Comparative Example 1 and Comparative Example 6 was formed by vapor deposition using a single Ti-Si-W alloy target material in the same manner as the C layer of Example 6. However, compared with the example, since the absolute values of the device temperature and the bias voltage are large and the N2 gas pressure is small, it becomes an environment in which it is difficult to form a repeated change in W concentration, and thus no repeated change in W concentration was formed.

[0195] Regarding the above-prepared Examples 1 to 6 and Comparative Examples 1 to 6, by using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS), the composition of the A layer and the B layer and the layer thickness of each layer were measured at multiple positions in the longitudinal section of the coating layer, and the average composition and the average layer thickness of each layer were calculated by taking the average value.

[0196] In addition, the B layer was measured in the layer thickness direction using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS) to obtain a composition distribution curve in the layer thickness direction.

[0197] For the Si component of the obtained composition distribution curve, smoothing processing using moving average was performed to remove noise, and the average value Si max of the maximum value of the Si component concentration at the maximum Si component-containing point and the average value Si of the minimum value of the Si component concentration at the minimum Si component-containing point were obtained. max 、the average value of the minimum value of the Si component concentration at the minimum Si-containing point of the Si componentmin Moreover, measure the interval between the maximum Si content point and the minimum Si content point of adjacent Si. Conduct this measurement at multiple locations, and obtain the average interval between the maximum and minimum Si content points as the average value.

[0198] In addition, for the C layer, in the same manner, obtain the average value W of the maximum value of the concentration of the W component at the maximum W content point max , the average value W of the minimum value of the concentration of the W component at the minimum W content point min , and measure the interval between the maximum W content point and the minimum W content point of adjacent W. Conduct this measurement at multiple locations, and obtain the average interval between the maximum and minimum W content points as the average value.

[0199] In addition, perform X-ray diffraction on the entire A layer and B layer in a direction perpendicular to the surface of the tool substrate, measure the full width at half maximum of the aggregated X-ray diffraction peak from the (200) plane (the X-ray diffraction peak where the A layer and B layer overlap), and from the intensity I of the aggregated X-ray diffraction peak (the X-ray diffraction peak where the A layer and B layer overlap) AB200 、I AB111 value, calculate the I AB200 / I AB111 value.

[0200] In addition, perform X-ray diffraction on the C layer, measure the X-ray diffraction peak intensity I C200 of the 200 diffraction line, the X-ray diffraction peak intensity I C111 of the 111 diffraction line, and calculate the I C200 / I C111 value.

[0201] In addition, for X-ray diffraction, use an X-ray diffractometer that uses a Cu tube target.

[0202] Figure 7 Indicates the X-ray diffraction results (vertical axis is X-ray intensity, horizontal axis is angle) measured for the entire A layer and B layer of Example 6. According to Figure 7 The full width at half maximum of the aggregated I of the hard coating layer composed of the A layer and B layer calculated from the results is 0.5 degrees, and the value of the ratio of I AB200 to I AB200 is I AB111 / I AB200 / I AB111 is 1.7.

[0203] In addition, the I C200 / I C111 of the hard coating layer composed of the C layer is 0.9.

[0204] Tables 6 and 7 show the full width at half maximum of I AB200 and IAB200 / I AB111 、I C200 / I C111 The values of I for Comparative Example Tools 1 to 6 are shown in Tables 8 and 9. AB200 The full width at half maximum of I, AB200 / I AB111 、I C200 / I C111 and the values of I.

[0205] [Table 2]

[0206]

[0207] [Table 3]

[0208]

[0209] (Note) "-" indicates not used.

[0210] [Table 4]

[0211]

[0212] [Table 5]

[0213]

[0214] (Note) "-" indicates not used.

[0215] [Table 6]

[0216]

[0217] (Note) There are repeated changes in the Si concentration in the intermediate layer (Layer B).

[0218] [Table 7]

[0219]

[0220] [Table 8]

[0221]

[0222] (Note) "-" in the intermediate layer indicates no repeated change in the Si concentration.

[0223] [Table 9]

[0224]

[0225] (Note) "-" indicates no repeated change in the W concentration.

[0226] Next, wet high-speed and high-feed open-hole cutting tests of SCM440 were carried out on Examples 1 to 7 and Comparative Examples 1 to 6 under the following conditions (the normal cutting speed and feed rate were 50 m / min. and 0.06 mm / rev, respectively) (using water-soluble cutting oil).

[0227] Workpiece - planar dimension: Plate of alloy steel SCM440

[0228] Cutting speed: 70 m / min.

[0229] Feed rate: 0.08 mm / rev

[0230] Hole depth: 40 mm

[0231] Measure the number of open-hole machining until the flank wear width of the front cutting edge surface reaches 0.3 mm, or until chipping, defect generation, or breakage occurs at the tip, or until the life is reached due to breakage, and observe the wear state of the tip. The machining was carried out up to 1000 holes of open-hole machining, and for the cases where the life was not reached, the flank wear width at the time of 1000-hole machining was measured.

[0232] Table 10 shows the measurement results.

[0233] [Table 10]

[0234]

[0235] (Note) ※ indicates the number of open-hole machining until the life is reached due to chipping, defect, or breakage.

[0236] According to the results in Table 10, in Examples 1 to 7, the average value of the flank wear width was about 0.13 mm, and no chipping, defect, or breakage was confirmed. In contrast, in Comparative Examples 1 to 6, the flank wear progressed, and there were also cases where the life was reached due to chipping, defect, or breakage in a short time.

[0237] <Example B>

[0238] An example corresponding to an embodiment of a coated tool having a coating layer as shown in Figure 3 will be described, where the coating layer has a lower layer (A layer), an intermediate layer (D layer), and an upper layer (C layer).

[0239] The WC-based cemented carbide drill substrates 1 to 3 manufactured in Example A were loaded into Figure 5 and Figure 6 the arc ion plating apparatus shown, and the lower layer (A layer) was formed under the conditions shown in Table 2 in the same manner as the film-forming steps (a) to (c) of Example A.

[0240] Next, under the following conditions (f) to (h), a middle layer (layer D having an alternating laminated structure of layer B and layer A) is formed.

[0241] (f) In the same manner as in step (d) of Example A, a layer B with a specified average layer thickness having a repeated change in Si concentration is formed. Then, the deposition of the Al-Cr-Si alloy target is stopped, and a specified current within the range of 100 - 150 Å shown in Table 2 is passed between the Al-Cr alloy target and the anode electrode to generate arc discharge, thereby forming layer A with a specified average layer thickness.

[0242] (g) By repeatedly performing the above step (f), a middle layer composed of layer D with a specified average layer thickness is formed. In addition, the middle layer is formed such that its surface (the layer closest to the tool surface side) is layer B.

[0243] (h) On the surface of the middle layer composed of layer D formed by the above step (g), in the same manner as in the film deposition step (e) of Example A, an upper layer of layer C with a specified layer thickness is formed by evaporation under the conditions shown in Table 3.

[0244] In the above steps, Examples 11 - 17 with a hard coating layer were fabricated. The hard coating layer has a lower layer (layer A) shown in Table 11, a middle layer (layer D composed of an alternating laminated structure of layer B and layer A), and an upper layer (layer C) shown in Table 12.

[0245] Regarding the fabricated Examples 11 - 17, the average composition and average layer thickness of each layer were calculated in the same manner as in Example A.

[0246] In addition, by measuring along the layer thickness direction using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an energy dispersive X-ray spectroscopy (EDS), the interval between the maximum Si content point and the minimum Si content point of adjacent Si in layer D was measured, and the average value Si max and the average value Si min were calculated, and the average interval between the maximum Si content point and the minimum Si content point of adjacent Si was obtained.

[0247] Furthermore, for layer C, the average value W max and the average value W min were calculated, and the average interval between the maximum W content point and the minimum W content point of adjacent W was obtained.

[0248] X-ray diffraction was performed on the lower layer and the middle layer, and the full width at half maximum of the X-ray diffraction peak (the X-ray diffraction peak where layer A and layer B overlap) of the 200 diffraction line was measured. And based on the intensity I of the summarized X-ray diffraction peak (the X-ray diffraction peak where layer A and layer B overlap)AB200 , I AB111 Calculate the value of I AB200 / I AB111 value.

[0249] Perform X-ray diffraction on the C layer and measure the X-ray diffraction peak intensity I of the 200 diffraction line C200 and the X-ray diffraction peak intensity I of the 111 diffraction line C111 , calculate I C200 / I C111 value.

[0250] Table 11 and Table 12 show the various values obtained above.

[0251] [Table 11]

[0252]

[0253] (Note) The intermediate layer (D layer) is an alternating laminated structure of the A layer and the B layer, and there are repeated changes in the Si concentration in the B layer.

[0254] [Table 12]

[0255]

[0256] Next, perform wet high-speed high-feed hole cutting tests on SCM440 under the following conditions for Examples 11 to 17 (the normal cutting speed and feed rate are 50 m / min. and 0.06 mm / rev respectively) (using water-soluble cutting oil).

[0257] Workpiece - Plane size: Steel plate of alloy steel SCM440

[0258] Cutting speed: 80 m / min.

[0259] Feed rate: 0.09 mm / rev

[0260] Hole depth: 40 mm

[0261] Measure the number of hole openings until the flank wear width of the front cutting edge surface reaches 0.3 mm, or until chipping or breakage of the tool tip occurs or the tool reaches its life due to breakage, and observe the wear state of the tool tip. The machining is carried out until 1000 holes are opened, and for the cases where the life is not reached, measure the flank wear width during the machining of 1000 holes.

[0262] Table 13 shows the test results.

[0263] [Table 13]

[0264]

[0265] [Example C]

[0266] An embodiment corresponding to an embodiment of a coating tool having a coating layer as shown in Figure 4 will be described, where the coating layer has a lower layer (layer A), an intermediate layer (layer D), an intimate layer (layer E), and an upper layer (layer C).

[0267] The WC-based cemented carbide drill bit substrates 1 to 3 produced in Example A were loaded into Figure 5 and Figure 6 the arc ion plating apparatus shown. Similar to the case of Example B, the lower layer (layer A) was formed under the conditions shown in Table 2. In addition, the intermediate layer (layer D) shown in the film forming steps (f) and (g) of Example B was formed.

[0268] Then, the film forming step of (i) was performed.

[0269] (i) Starting from the middle of the film formation of the B layer on the outermost surface of the intermediate layer (layer D), the film formation of the Al-Cr alloy target was stopped. At the same time, under the conditions shown in Table 3, the co-evaporation of layer C was started. By temporarily continuing the co-evaporation of layer B and layer C, an intimate layer (layer E) was formed.

[0270] Then, the evaporation of layer B was stopped. Under the conditions shown in Table 3, by only continuing the evaporation of layer C, an upper layer composed of layer C with a specified layer thickness was formed by evaporation.

[0271] Through the above-mentioned process, Examples 21 to 27 shown in Table 14 having a hard coating layer were produced. The hard coating layer was composed of the lower layer (layer A) shown in Table 11, an intermediate layer (layer D composed of an alternating laminated structure of layer B and layer A), an intimate layer (layer E), and an upper layer (layer C).

[0272] In addition, in the intimate layer (layer E), a composition modulation structure of Si was formed.

[0273] Regarding Examples 21 to 27 produced above, in the same manner as in Examples A and B, the average composition of each layer and the average layer thickness of one layer were calculated.

[0274] In addition, in the same manner as in Examples A and B, for layer E and layer C, the average interval between the maximum Si content point and the minimum Si content point of Si, Si max(E) Si min(E) the average interval between the maximum W content point and the minimum W content point of W, W max W min were obtained.

[0275] In addition, in the same manner as in Examples A and B, the full width at half maximum of the aggregated X-ray diffraction peaks of the 111 diffraction line and the 200 diffraction line were measured for the entire A layer and B layer, and the I AB200 / I AB111 value was calculated.

[0276] In addition, the I C200 / I C111 value was calculated for the C layer.

[0277] Table 14 shows various values.

[0278]

[0279] Next, under the same cutting conditions as in Example B, wet high-speed high-feed open-hole cutting tests were conducted on Examples 21 to 27. The number of open-hole machining operations was measured until the flank wear width of the flank face up to the tip cutting edge reached 0.3 mm or until the life was reached due to chipping, defect generation, or drill breakage of the tip, and the wear state of the tip was observed. The machining was carried out up to 1000 open-hole machining operations, and for cases where the life was not reached, the flank wear width during 1000-hole machining was measured.

[0280] Table 15 shows the test results.

[0281] [Table 15]

[0282]

[0283] Based on the results of Tables 13 and 15, in Examples 11 to 17 and 21 to 27, the average values of the flank wear width were small, approximately 0.12 mm and approximately 0.11 mm, respectively, the wear resistance was excellent, the generation of chipping and defects was suppressed, and furthermore, drill breakage did not occur.

[0284] In particular, it was found that Examples 21 to 27 had more excellent wear resistance compared to Examples 11 to 17.

[0285] In addition, the cutting test results of the comparative examples were not shown for the cutting tests corresponding to Tables 13 and 15. However, since this cutting test was more stringent than the cutting test in Table 10, even if the cutting test for the comparative examples was not actually conducted, the wear of the flank face of the comparative examples would progress, resulting in a short life, which was obvious from the results of Table 10.

[0286] From these results, it was found that the examples exhibited excellent chipping resistance, defect resistance, and wear resistance in high-load cutting of workpieces such as carbon steel, alloy steel, and stainless steel, and drill breakage of the drill tool did not occur.

[0287] The foregoing disclosed embodiments are illustrative in all respects and not restrictive. The scope of the present invention is represented by the claims, rather than by the foregoing embodiments, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0288] Description of Reference Numerals

[0289] 1 Tool substrate

[0290] 2 Lower layer

[0291] 3 Intermediate layer

[0292] 3' Intermediate layer (alternate laminated structure)

[0293] 4 Upper layer

[0294] 5 Close contact layer

[0295] 10 A layer ((Al, Cr)N layer)

[0296] 11 B layer ((Al, Cr, Si)N layer)

[0297] 12 C layer ((Ti, Si, W)N layer)

[0298] 13 D layer (alternate laminated structure of A layer and B layer)

[0299] 14 E layer ((Al, Ti, Cr, Si, W)N layer)

[0300] 20 Anode electrode

[0301] 21 Ti - Si - W alloy target (cathode electrode)

[0302] 22 Al - Cr - Si alloy target (cathode electrode)

[0303] 23 Al - Cr alloy target (cathode electrode)

[0304] 24 Heater

[0305] 25 Rotary table

[0306] 26 Tool substrate (showing overall shape)

[0307] 27 Reaction gas inlet

[0308] 28 Exhaust port

[0309] 29 Arc power supply

[0310] 30 Bias power supply

[0311] 31 Peak of h - WC

[0312] 111 diffraction peak of layer 32 C

[0313] 33 Summarize the 111 diffraction peaks of layer A and layer B

[0314] 34 200 diffraction peak of layer C

[0315] 35 Summarize the 200 diffraction peaks of layer A and layer B

Claims

1. A surface-coated cutting tool having a tool substrate and a coating layer on the surface of the tool substrate, characterized in that, 1) The average layer thickness of the coating layer is 0.5 to 8.0 μm, and the coating layer successively has a lower layer, an intermediate layer, and an upper layer from the tool substrate side toward the tool surface, 2) The lower layer having an average layer thickness of 0.1 to 4.0 μm is composed of a layer A having a composition formula: (Al 1-x Cr x )N represents the average composition of the A layer, and x is 0.20 to 0.60, 3) The intermediate layer with an average layer thickness of 0.1 to 4.0 μm is composed of layer B. When the average composition of layer B is represented by the compositional formula: (Al 1-a-b Cr a Si b )N, a is 0.20 to 0.60, and b is 0.01 to 0.

20. 4) The B layer has a repeated change in Si concentration with an average interval between adjacent maximum and minimum values of 1 to 100 nm, When setting the average value of the maximum value of the Si concentration to Si max 1.0 < Si max / b ≤ 2.0, Further, when the average value of the minimum value of the Si concentration is set to Si min 0.0 ≤ Si min / b < 1.0 5) The upper layer with an average layer thickness of 0.1 to 4.0 μm is composed of a C layer. When the average composition of the C layer is represented by the compositional formula: (Ti 1-α-β Si α W β )N, α is 0.01 to 0.20 and β is 0.01 to 0.

10. 6) The C layer has a repeated change in W concentration with an average interval between adjacent maximum and minimum values of 1 to 100 nm, When setting the average value of the maximum value of the W concentration to W max 1.0 < W max / β ≤ 2.0, Also, when the average value of the minimum value of the W concentration is set to W min , 0.0 ≤ W min / β < 1.

0.

2. A surface-coated cutting tool having a tool substrate and a coating layer on the surface of the tool substrate, characterized in that, 1) The average layer thickness of the coating layer is 0.5 to 8.0 μm, and the coating layer successively has a lower layer, an intermediate layer, and an upper layer from the tool substrate side toward the tool surface, 2) The lower layer with an average layer thickness of 0.1 to 4.0 μm is composed of layer A. When the average composition of layer A is represented by the compositional formula: (Al 1-x Cr x )N, x is 0.20 to 0.60, 3) The intermediate layer is a D layer with an average layer thickness of 0.5 to 4.0 μm. The D layer is an alternating laminated structure of a B layer and the A layer. Two or more of the B layers are included in the D layer. When the average composition of the B layer is represented by the compositional formula: (Al 1-a-b Cr a Si b )N, a is 0.20 to 0.60 and b is 0.01 to 0.

20. 4) The B layer has a repeated change in Si concentration with an average interval between adjacent maximum and minimum values of 1 to 100 nm, When setting the average value of the maximum value of the Si concentration to Si max 1.0 < Si max / b ≤ 2.0, Further, when the average value of the minimum value of the Si concentration is set to Si min 0.0 ≤ Si min / b < 1.0 5) The upper layer with an average layer thickness of 0.1 to 4.0 μm is composed of a C layer. When the average composition of the C layer is represented by the compositional formula: (Ti 1-α-β Si α W β )N, α is 0.01 to 0.20 and β is 0.01 to 0.

10. 6) The C layer has a repeated change in W concentration with an average interval between adjacent maximum and minimum values of 1 to 100 nm, When setting the average value of the maximum value of the W concentration to W max 1.0 < W max / β ≤ 2.0, Further, when the average value of the minimum value of the W concentration is set to W min 0.0 ≤ W min / β < 1.

0.

3. The surface-coated cutting tool according to claim 1, characterized in that, There is an intimate layer with an average layer thickness of 0.1 to 2.0 μm between the intermediate layer and the upper layer. The intimate layer is composed of an E layer. When the composition of the E layer is represented by the composition formula: (Al 1-k-l-m-n Ti k Cr l Si m W n )N, k is 0.20 to 0.65, l is 0.10 to 0.35, m is greater than 0.00 and 0.15 or less, and n is greater than 0.00 and 0.05 or less. The E layer has a repeated change in Si concentration with an average interval between adjacent maximum and minimum values of 1 to 100 nm, When setting the average value of the maximum value of the Si concentration to Si max(E) , 1.0 < Si max(E) / m ≤ 2.0, Further, when the average value of the minimum value of the Si concentration is set to Si min(E) 0.0 ≤ Si min(E) / b < 1.0 4. The surface-coated cutting tool according to claim 2, characterized in that, There is an intimate layer with an average layer thickness of 0.1 to 2.0 μm between the intermediate layer and the upper layer. The intimate layer is composed of an E layer. When the composition of the E layer is represented by the compositional formula: (Al 1-k-l-m-n Ti k Cr l Si m W n )N, k is 0.20 to 0.65, l is 0.10 to 0.35, m is greater than 0.00 and 0.15 or less, and n is greater than 0.00 and 0.05 or less. The E layer has a repeated change in Si concentration with an average interval between adjacent maximum and minimum values of 1 to 100 nm, When setting the average value of the maximum value of the Si concentration as Si max(E) 1.0 < Si max(E) / m ≤ 2.0, Further, when the average value of the minimum value of the Si concentration is set to Si min(E) 0.0 ≤ Si min(E) / b < 1.

0.

5. The surface-coated cutting tool according to any one of claims 1 to 4, characterized in that, Each layer constituting the coating layer contains grains having a rock-salt type cubic crystal structure, When summing up the X-ray diffraction peaks obtained from the A layer and the B layer respectively and calculating the full width at half maximum of the peak of the 200 diffraction line, the full width at half maximum of the peak of the 200 diffraction line is 0.2 to 1.0 degrees. When setting the peak intensity of the 200 diffraction line as I AB200 and setting the peak intensity of the 111 diffraction line as I AB111 at this time, 0.5 < I AB200 / I AB111 < 10.0, When setting the peak intensity of the 200 diffraction line of the C layer to I C200 and setting the peak intensity of the 111 diffraction line to I C111 , 0.5 < I C200 / I C111 < 10.0.

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