Surface-coated cutting tools

Abstract

A surface-coated cutting tool having a laminate layer comprising a first layer and a second layer of a cubic structure with an average thickness of 0.5 to 8 μm, wherein a layer on each of a substrate side and a front surface side is the first layer. The first layer has an average thickness of 0.1 to 2 μm and comprises (Al1-x Crx)Ｎ, where x = 0.20 to 0.60. The second layer has an average thickness of 0.1 to 2 μm, comprises (Al1-a-bCraSib)N, where a = 0.20 to 0.60, b = 0.01 to 0.20, and has an Si content varying repeatedly with an average interval between a maximum value and a minimum value being 1 to 100 nm, an average maximum value Simax satisfying 1.0 < Simax / b ≤ 2.0, an average minimum value Simin satisfying 0.0 ≤ Simin / b < 1.0, and a half width of a diffraction peak of a 111 diffraction line being 0.1 to 1.0 degree. When a diffraction peak intensity of the diffraction line is I111 and a diffraction peak intensity of a 200 diffraction line is I200, then I111 / I200 is greater than 1 and less than 5.

Description

[Technical Field]

[0001] The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool). This application claims priority to Japanese Patent Application No. 2020-212386, filed on December 22, 2020. The entire contents of this Japanese patent application are incorporated herein by reference. [Background technology]

[0002] In order to improve the lifespan of conventional cutting tools, there are coated tools in which a coating layer is formed on the surface of a substrate such as a tungsten carbide (hereinafter referred to as WC)-based cemented carbide, and these coated tools have improved wear resistance. In order to further improve the cutting performance of coated tools, various proposals have been made regarding the composition and structure of the coating layer.

[0003] For example, Patent Document 1 describes a coated tool in which (AlCrSi)(NOBC) is used as a coating layer, the half-width of the 111 or 200 diffraction peak is set to 0.5 to 2.0 degrees, and more oxygen is present at the crystal grain interfaces than inside the crystal grains in the coating layer, and the coated tool is said to have improved wear resistance.

[0004] Furthermore, for example, Patent Document 2 describes a coated tool in which the coating layer is an alternating laminate coating layer of a first layer of (AlCrSi)N and a second layer of (TiSi)N, and in which, when the peak intensity of the 111 diffraction ray of the first layer is Ir, the peak intensity of the 200 diffraction ray is Is, and the peak intensity of the 220 diffraction ray of the first layer is It, Is / Ir=1 to 10 and It / Ir=0.6 to 1.5, and when the interplanar spacing of the 200 diffraction ray of the first layer and the second layer is d1 and d2, respectively, the relationship is 0.965≦d1 / d2≦0.990, and the second layer has a columnar crystal structure and the Si content changes repeatedly; the coated tool is said to have excellent wear resistance.

[0005] Furthermore, for example, Patent Document 3 describes a coated tool having a first coating layer of (AlCr)N and a second coating layer of (TiSi)N with an average thickness of 4 to 10 μm, wherein the first layer has a half width W1 of the 111 diffraction line of 0.7 to 1.1 degrees, and where Ir is the peak intensity of the 111 diffraction line, Is is the peak intensity of the 200 diffraction line, and It is the peak intensity of the 220 diffraction line, the following relationships are satisfied: 0.3≦Is / Ir≦1.0, 0.3≦It / Ir<1; and the second layer has a half width W2 of the 111 diffraction line of 0.6 to 1.1 degrees, and where Iu is the peak intensity of the 111 diffraction line, Iv is the peak intensity of the 200 diffraction line, and Iw is the peak intensity of the 220 diffraction line, the following relationships are satisfied: 0.3≦Iv / Iu<1, 0.3≦Iw / Iu<1; and the coated tool is said to have excellent wear resistance.

[0006] Additionally, for example, Patent Document 4 describes a coated tool in which first layers of (AlCr)N and second layers of (TiSi)N are alternately laminated as a coating layer, the first layers and the second layers each have a thickness of 1 to 20 nm, and a mixed structure portion having a structure in which the components of the first layer and the components of the second layer are mixed accounts for 5 to 80% of the cross-sectional area of ​​the entire coating layer, and the coated tool is said to have excellent wear resistance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-126736 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-93085 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-45650 [Patent Document 4] Patent No. 5087427 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances and proposals, and has an object to provide a surface-coated cutting tool having excellent wear resistance and chipping resistance. [Means for solving the problem]

[0009] The surface-coated cutting tool according to an embodiment of the present invention comprises: 1) A substrate and a coating layer on the surface of the substrate, 2) The coating layer has an average thickness of 0.5 μm or more and 8.0 μm or less, and has a laminate layer in which one or more first layers and one or more second layers are alternately laminated, 3) the layer of the laminate closest to the substrate and the layer closest to the surface are both the first layer, 4) The first layer has an average thickness of 0.1 μm or more and 2.0 μm or less, and (Al 1-x Cr x )N (0.20≦x≦0.60), 5) The second layer has an average thickness of 0.1 μm or more and 2.0 μm or less, and (Al 1-a-b Cr a Si b )N (0.20≦a≦0.60, 0.01≦b≦0.20), in a direction perpendicular to the surface of the substrate The Si content repeatedly changes so that the average distance between adjacent maximum and minimum values ​​is 1 nm or more and 100 nm or less, and the average value Si max But 1.0 <Si max / b≦2.0, and the average value Si of the minimum values ​​of the Si content min However, 0.0≦Si min / b<1.0, 6) Both the first layer and the second layer have crystal grains with an NaCl-type face-centered cubic structure, 7) When the X-ray diffraction peaks of the first layer and the second layer are summarized, the half-width of the diffraction peak of the 111 diffraction ray is 0.1 degree or more and 1.0 degree or less, and the diffraction peak intensity of the 111 diffraction ray is I 111 , the diffraction peak intensity of the 200 diffraction line is I 200 When I 111 / I 200 is greater than 1.0 and less than 5.0.

[0010] Furthermore, the surface-coated cutting tool according to the embodiment has one or more of the following (1) or (2), or (2 and (3), or (1) to ( 3 ) may satisfy all of the items.

[0011] (1) The first layer of the laminate layer closest to the surface of the tool is replaced with a layer having an average composition of (Al 1-y Cr y )N(0.20≦y≦0.60), and the average thickness thereof is 0.3 μm or more and 4.0 μm or less, and the third layer has an average thickness greater than that of the other first layers of the laminate layer.

[0012] (2) The first layer or the third layer of the laminated layer, which is closest to the surface of the tool, has an average thickness of 0.1 μm or more and 4.0 μm or less, and its average composition is (Ti 1-α-β Si α W β )N(0.01≦α≦0.20, 0.01≦β≦0.10), The W content has repeated changes in which the average distance between adjacent maximum and minimum values ​​is 1 nm or more and 100 nm or less, and the average value W of the maximum values ​​of the W content max is 1.0 <W max / β≦2.0, and the average value W of the minimum value of the W content min is 0.0≦W min Having a surface layer with β<1.0.

[0013] (3) Between the first layer or the third layer of the laminate layer closest to the surface of the tool and the surface layer, the average thickness is 0.1 μm or more and 2.0 μm or less, and the average composition is (Al 1-k-l-m-n Ti k Cr l Si m W n )N(0.20≦k≦0.65, 0.10≦l≦0.35, 0.00< m ≦0.15, 0.00 <n≦0.05)であり、 The Si content has repeated changes such that the average distance between adjacent maximum and minimum values ​​is 1 nm or more and 100 nm or less, and the average value of the maximum values ​​of the Si content is expressed as Sim max But 1.0 <Sim max / m≦2.0, and the average value Sim of the minimum value of the Si content min However, 0.0≦Sim min / m<1.0. [Effects of the Invention]

[0014] The surface-coated cutting tool has excellent wear resistance and chipping resistance. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram schematically showing a vertical cross section of a coating layer of a surface-coated cutting tool according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram schematically illustrating a portion of an example of repeated changes in Si content in a longitudinal section of a coating layer of a surface-coated cutting tool according to one embodiment of the present invention. [Figure 3] FIG. 4 is a diagram schematically showing a vertical cross section of a coating layer of a surface-coated cutting tool according to another embodiment of the present invention. [Figure 4] 10 shows the results of X-ray diffraction measurement of the coating layer of Example 4. [Figure 5] 10 shows the results of X-ray diffraction measurement of the coating layer of Example 14. [Figure 6] FIG. 2 is a schematic plan view of an arc ion plating apparatus used to form a coating layer in Examples A and B. [Figure 7] FIG. 7 is a schematic front view of the arc ion plating apparatus of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present inventors have investigated a composite nitride layer of Al, Cr, and Si (hereinafter, sometimes referred to as (AlCrSi)N). As a result, they have found that Al improves high-temperature hardness and heat resistance, Cr improves high-temperature strength, and the coexistence of Al and Cr also improves high-temperature oxidation resistance. Furthermore, although Si improves heat resistance, the inclusion of Si increases lattice strain in the (AlCrSi)N layer, so that when a high load is applied, the layer does not have enough toughness to withstand the load, and is prone to chipping and fracture.

[0017] The present inventors have also found that simply laminating the coating layer by laminating an (AlCrSi)N layer with another known coating layer (for example, a composite nitride layer of Ti and Si) results in a further decrease in the toughness of the coating layer as a whole due to strain caused by lattice constant mismatch at the lamination interface with this other hard phase, in addition to the low toughness of the (AlCrSi)N layer itself, making it difficult to avoid chipping and fracture.

[0018] Therefore, the inventors have conducted further studies and found that by setting the composition of the (AlCrSi)N layer within a predetermined range, forming a laminated structure with another coating layer that has good adhesion to both the substrate and the (AlCrSi)N layer, i.e., a composite nitride of Al and Cr (hereinafter, sometimes referred to as (AlCr)N), and by having the (AlCrSi)N layer have a predetermined XRD pattern, Furthermore, in addition to this laminated structure and XRD pattern, a composite nitride layer of Ti, Si and W (hereinafter sometimes referred to as (TiSiW)N) was laminated, and the Si content was repeatedly changed. In addition, by selectively stacking a composite nitride of Al, Ti, Cr, Si, and W (hereinafter, sometimes referred to as (AlTiCrSiW)N) and repeatedly changing the W content, The inventors have obtained a novel finding that by improving the adhesion of the coating layer to the substrate and between the individual laminations, and by increasing the toughness of the entire coating layer, it is possible to obtain a coated tool that exhibits excellent wear resistance over a long period of time and is suppressed from chipping and fracture, even under severe cutting conditions in which continuous and intermittent cutting processes act in combination (hereinafter sometimes referred to as high-load cutting conditions).

[0019] Hereinafter, a coated tool according to an embodiment of the present invention will be described in detail. In this embodiment, the films are formed so that no layers other than the first to fifth layers exist; however, when changing the layer to be formed (changing the film formation to another adjacent layer), fluctuations in pressure within the film formation apparatus inevitably occur, and layers containing unintended oxygen or carbon with compositions different from those of the adjacent layers may be formed between the adjacent layers. In this specification and claims, when a numerical range is expressed as "L to M" (where L and M are both numerical values), the range includes an upper limit (M) and a lower limit (L), and when a unit is stated only for the upper limit (M), the upper limit (M) and the lower limit (L) have the same unit.

[0020] I. The embodiment shown in FIG. FIG. 1 is a diagram showing a surface-coated cutting tool according to one embodiment of the present invention. Vertical section First, the embodiment shown in FIG. The longitudinal section refers to a section perpendicular to the surface of the substrate, ignoring minute irregularities on the surface of the substrate.

[0021] 1.Coating layer In this embodiment, as is clear from Fig. 1, the coating layer has a first layer (2) on a substrate (1), and a laminate layer in which the first layer (2) and the second layer (3) are alternately laminated. As will be described later, a third layer (4) may be provided on the outermost surface side (tool surface side) of the coated tool (i.e., the first layer may be provided instead of the third layer). Fig. 1 shows an embodiment in which the third layer (4) is provided instead of the first layer (2) on the tool surface side.

[0022] (1) First layer In the (AlCr)N layer, which is the first layer constituting the laminated layer of the coating layer, Al improves high-temperature hardness and heat resistance, while Cr improves high-temperature strength. In addition, the coexistence of Cr and Al improves high-temperature oxidation resistance.

[0023] The average composition of the first layer, which is (AlCr)N, is Formula: (Al 1-x Cr x )N When expressed as x, the x value, which indicates the Cr content, is preferably 0.20 or more and 0.60 or less. The reason for this is that if the x value is less than 0.20, the high-temperature strength decreases, resulting in a deterioration in chipping resistance, and the increase in the relative Al content causes the appearance of crystal grains with a hexagonal crystal structure, resulting in a decrease in hardness and wear resistance. On the other hand, if the x value exceeds 0.60, the decrease in the relative Al content makes it impossible to ensure sufficient high-temperature hardness and heat resistance, resulting in a decrease in wear resistance. A more preferable range for the x value is 0.25 or more and 0.50 or less.

[0024] According to an example of the manufacturing method described below, the ratio of (AlCr) to N is manufactured to be 1:1, but inevitably (unintentionally) there may be some composite nitrides that do not have a ratio of 1:1. This also applies to other composite nitrides described below.

[0025] (2)Second layer In the (AlCrSi)N layer, which is the second layer that constitutes the laminate layer together with the first layer, Cr improves the high-temperature strength and chipping resistance of the coating layer, just like the first layer. In addition, when coexisting with Al, Cr contributes to improving high-temperature oxidation resistance and wear resistance. In addition, Si, a constituent component of the second layer, has the effect of improving heat resistance and thermal plastic deformation resistance, but at the same time, it increases the lattice strain of the second layer, resulting in a decrease in the chipping resistance of the second layer, which causes repeated changes in the content as described below.

[0026] The average composition of the second layer, which is (AlCrSi)N, is Formula: (Al 1-a-b Cr a Si b )N When expressed as a, the a-value, which indicates the Cr content, is preferably 0.20 or more and 0.60 or less. The reason is that if the a-value is less than 0.20, the high-temperature strength decreases, resulting in a deterioration of chipping resistance, and the increase in the relative Al content causes the appearance of crystal grains with a hexagonal crystal structure, resulting in a decrease in hardness and wear resistance. On the other hand, if the a-value exceeds 0.60, the decrease in the relative Al content makes it impossible to ensure sufficient high-temperature hardness and heat resistance, resulting in a decrease in wear resistance. A more preferable range for the a-value is 0.25 or more and 0.50 or less.

[0027] The b-value is preferably 0.01 or more and 0.20 or less. This is because, if the b-value is less than 0.01, the improvement in heat resistance and thermal plastic deformation resistance in the second layer is small, while if it exceeds 0.20, the improvement in wear resistance tends to decrease, and at the same time, the lattice strain in the second layer increases, increasing the lattice mismatch between the first and second layers, resulting in a decrease in chipping resistance, especially under high-load cutting conditions. A more preferable range for the b-value is 0.01 or more and 0.15 or less.

[0028] Furthermore, to more reliably reduce lattice strain, it is preferable that the average value of the interval between adjacent maximum and minimum values ​​of the Si content, i.e., the average interval in the direction perpendicular to the surface of the substrate (thickness direction, as defined below), be cyclically changed so that it is 1 nm or more and 100 nm or less. In other words, this cyclic change suppresses abrupt changes in the Si content between the first and second layers, more reliably reducing lattice strain, which is presumed to result in improved adhesion between the two layers, prevent peeling of the coating layer, and improve chipping resistance and defect resistance.

[0029] The reason why the average spacing between adjacent maximum and minimum values ​​of the Si content is set to 1 nm or more and 100 nm or less is that if the average spacing is less than 1 nm, the Si content will change abruptly, causing localized large lattice strain and reducing chipping resistance, while if the average spacing is more than 100 nm, the area with high Si content, i.e., large lattice strain, will become wider, making chipping more likely to occur from that area and reducing chipping resistance. A more preferable range for the average spacing of repeated changes is 5 nm or more and 50 nm or less.

[0030] Fig. 2 is a diagram schematically illustrating a portion of an example of repeated changes in the Si content. In Fig. 2, the maximum and minimum values ​​are the same, and the intervals between adjacent maximum and minimum values ​​are also the same. However, the repeated changes in the Si content referred to in this specification and claims only need to refer to changes in the Si content that alternate between maximum and minimum values, and the maximum and minimum values ​​may or may not be the same, and the intervals between adjacent maximum and minimum values ​​may or may not be the same.

[0031] In addition, the average value of the maximum Si content is max When this is done, it becomes 1.0 <Si max / b≦2.0, and the average value of the minimum Si content is Si min When 0.0≦Si min It is preferable that / b<1.0, where b is the average Si content b in the formula of the second layer.

[0032] Ratio of the average value of the maximum Si content to bSi max / b and the ratio of the average value of the minimum value to b, Si min The reason for setting / b as above is that Si max / b is greater than 1.0 and Si min If / b is less than 1.0, the lattice strain can be reduced by repeatedly changing the Si content. max If / b exceeds 2.0, the range of change in the composition becomes large, causing a sudden change in the Si content and resulting in a decrease in chipping resistance. Simax / b, Si min A more preferable range for / b is 1.2 <Si max / b≦2.0, 0.0≦Si min / b<0.8.

[0033] Here, the average distance between the position giving the maximum value of Si and the adjacent position giving the minimum value in the second layer having a repeated change in Si content can be determined by measuring the Si content in the thickness direction of the second layer, removing measurement noise as known in the art, and plotting the result on a graph.

[0034] That is, as shown in Figure 2, a line m is drawn across the curve showing the cyclic change in Si content (in Figure 2, line m indicates the length across two maximum values ​​and two minimum values, but the length of line m is not limited to this and may be any length that allows the average values ​​of the maximum values ​​and minimum values ​​and the average interval to be determined with high accuracy). This line m is drawn so that the areas of the regions enclosed by the curve are equal above and below line m. Then, for each region where line m crosses the curve showing the cyclic change in Si content, the maximum or minimum value of the Si content is determined, the interval between the two values ​​is measured, and the average interval of the cyclic change in Si content in the second layer is determined by averaging the measured values ​​at multiple locations.

[0035] In addition, the average value of the maximum Si content Si max and the average value of the minimum Si content Si min is calculated by averaging the measured values ​​of the maximum and minimum values ​​of the Si content obtained at multiple locations.

[0036] (3) Laminate layer The laminate layer is formed by alternately laminating first layers and second layers. The average thickness of the first layer and the second layer is preferably 0.1 μm or more and 2.0 μm or less, respectively. This average thickness range alleviates the lattice mismatch between the first layer and the second layer, improving the chipping resistance and wear resistance of the coating layer. As will be described later, the first layer, which is the layer closest to the surface of the coated tool, may be replaced with a third layer. Replacing it with a third layer may more reliably achieve the aforementioned objectives.

[0037] Furthermore, it is preferable to form a laminate layer having an average thickness of 0.5 μm to 8.0 μm by alternately laminating the first and second layers. This is because if the average thickness of the laminate layer is less than 0.5 μm, the laminate layer will not exhibit sufficient wear resistance over a long period of time, while if the average thickness exceeds 8.0 μm, abnormal damage such as chipping, fracture, and peeling will be more likely to occur. A more preferable range for this average thickness is 1.0 μm to 7.0 μm. The preferred range of the average thickness of this laminate layer (average thickness of the entire laminate layer) is the same as when the laminate layer has only the first and second layers, even when the laminate layer has the third to fifth layers described below.

[0038] It is preferable that the layer of the laminate layer closest to the substrate and the layer closest to the surface of the coated tool are both Layer 1. The reason for this is that by forming the Layer 1 on the layer closest to the substrate, the adhesive strength between the substrate and the laminate layer can be ensured, and by forming the Layer 1 on the layer closest to the surface of the coated tool, the laminate layer can ensure chipping resistance during high-load cutting.

[0039] Here, there are no particular restrictions on the number of layers of the first and second layers, as long as the first layer is the layer of the laminate closest to the substrate and the layer closest to the surface of the coated tool, the average thickness of each of the first and second layers is 0.1 μm or more and 2.0 μm or less, and the total thickness of the laminate is 0.5 μm or more and 8.0 μm or less. However, it is more preferable that there are 3 to 6 layers of each, for example, 5 first layers and 4 second layers.

[0040] The first layer of the laminate layer closest to the surface of the coated tool may be replaced by the third layer (or may not be the third layer). The third layer has an average composition represented by the formula: (Al 1-y Cr y )N, the atomic ratio y is 0.20 or more and 0.60 or less (y may or may not be the same as x), the average thickness is 0.3 μm or more and 4.0 μm or less, and the average thickness is greater than the average thickness of the other first layers of the laminate layer.

[0041] The reason for this is believed to be that the third layer, which is made of (AlCr)N and has relatively less lattice distortion than the second layer, is thicker than the first layer and is located closest to the surface of the coated tool. By providing this layer on the surface of the laminated layer, the impact absorption during high-load cutting is further improved. If the average thickness of the (AlCr)N layer closest to the surface of the coated tool is less than 0.3 μm, the chipping resistance is not sufficiently improved. On the other hand, if it exceeds 4.0 μm, the proportion of the (AlCr)N layer in the hard coating layer becomes too large, resulting in a decrease in wear resistance. The y value of the third layer is more preferably in the range of 0.25 to 0.50. Furthermore, the average thickness is more preferably in the range of 0.5 μm to 2.0 μm.

[0042] (4) NaCl-type face-centered cubic crystal grains The crystal grains constituting the first, second, and third layers preferably have an NaCl-type face-centered cubic structure, although these layers may contain an unavoidable (unintentional) amount of crystal grains having a crystal structure other than the NaCl-type face-centered cubic structure.

[0043] (5) XRD pattern When the X-ray diffraction peaks of the first layer, the second layer, and the third layer are summarized, the half-width of the diffraction peak of the 111 diffraction ray is 0.1 degrees or more and 1.0 degrees or less, and the diffraction peak intensity of the 111 diffraction ray is I 111 , the diffraction peak intensity of the 200 diffraction line is I 200 When I 111 / I 200is preferably more than 1.0 and less than 5.0. More preferably, the half width of the diffraction peak of the 111 diffraction line is 0.1 degrees or more and 0.5 degrees or less, and I 111 / I 200 is greater than 1.1 and less than 4.0.

[0044] The half width is within the above range, and I 111 / I 200 When the FWHM is within the above range, the laminate layer exhibits excellent chipping resistance and wear resistance. Although the reason for this is unclear, it is presumed that by setting the FWHM within the above range, the crystallinity of the laminate layer is improved and the difference in lattice constants of the crystals constituting the first, second, and third layers is reduced, thereby reducing strain due to lattice mismatch at the stacking interfaces of the first, second, and third layers, thereby improving wear resistance and chipping resistance. Furthermore, it is presumed that the peak intensity ratio is further improved by the preferential presence of the (111) plane, which is the close-packed plane of the NaCl-type face-centered cubic structure.

[0045] Here, "to summarize the X-ray diffraction peaks of the first and second layers" refers to X-ray diffraction peaks obtained by measuring the X-ray diffraction peaks of the first and second layers in an overlapping state rather than individually when performing X-ray diffraction on the first and second layers. Also, "to summarize the X-ray diffraction peaks of the first, second, and third layers" refers to X-ray diffraction peaks obtained by measuring the X-ray diffraction peaks of the first, second, and third layers in an overlapping state rather than individually when performing X-ray diffraction on the first, second, and third layers.

[0046] 2.Base (1)Material The substrate material may be any of the conventionally known substrate materials as long as it does not impede the achievement of the object of the present invention. For example, cemented carbide (WC-based cemented carbide, WC, Co, and carbonitrides of Ti, Ta, Nb, etc.), cermet (mainly composed of TiC, TiN, TiCN, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cBN sintered body, or diamond sintered body is preferable.

[0047] (2) Shape The shape of the substrate is not particularly limited as long as it is a shape that can be used as a cutting tool, and examples thereof include the shape of an insert and the shape of a drill.

[0048] 3. Manufacturing method The manufacturing method of this embodiment can be, for example, a film formation method using the following PVD method.

[0049] An arc discharge is generated between the Al-Cr alloy target and the anode electrode to form a first layer with a predetermined average thickness. Then, simultaneously with this arc discharge, a predetermined film formation condition (rotation of the rotary table) is applied between the Al-Cr-Si alloy and the anode electrode. speed The second layer having a repeatedly changed Si content is deposited by generating an arc discharge under the conditions (controlling the nitrogen pressure, bias voltage, and temperature in the PVD deposition apparatus at the time of arc discharge generation).

[0050] After depositing the second layer having a predetermined average thickness, the arc discharge between the Al-Cr-Si alloy and the anode electrode is stopped, and only the arc discharge between the Al-Cr alloy target and the anode electrode is continued to deposit the first layer having a predetermined average thickness. This process is then repeated to form a laminate layer having a predetermined number of first and second layers. A third layer may also be formed. When forming (AlCr)N layers with different average compositions for the first and third layers, an Al-Cr alloy target for forming the third layer is used for film formation, in addition to the Al-Cr alloy target for forming the first layer.

[0051] Here, by controlling the alloy composition of the targets used to form the first, second, and third layers and the film formation conditions to predetermined values, the predetermined X-ray diffraction pattern of this embodiment can be obtained.

[0052] The second layer can also be formed by a single arc discharge between the Al-Cr-Si alloy target and the anode electrode by adjusting the film formation conditions without generating a discharge between the Al-Cr alloy target and the anode electrode. However, in terms of controlling the repeated change in Si content and the X-ray diffraction pattern, the method of depositing a film using an Al-Cr alloy target is superior to the method of depositing a film using only an Al-Cr-Si alloy target.

[0053] II. The embodiment shown in FIG. 3 Fig. 3 is a schematic longitudinal cross-sectional view of a surface-coated cutting tool according to another embodiment of the present invention. Next, the embodiment shown in Fig. 3 will be described. Note that portions that overlap with the embodiment shown in Fig. 1 will not be described in detail.

[0054] 1.Coating layer (1) Laminate layer and its constituent layers This embodiment has a laminate layer having the same first layer (2), second layer (3), and optionally a third layer (4) as the embodiment shown in Fig. 1, and also has an optional surface layer (fourth layer) (5) on the tool surface side of the laminate layer, and further has an optional intermediate layer (fifth layer) (6) between the surface layer (5) and the third layer (4). Fig. 3 shows an embodiment having the optional third, fourth, and fifth layers. Here, "selectively having Layer A" means that it may or may not have Layer A. For example, the third layer may be the first layer (2) instead of (4).

[0055] (2) Surface layer In this embodiment, the laminate further includes a surface layer (fourth layer) having a predetermined composition and structure of a composite nitride of Ti, Si, and W (hereinafter, sometimes represented as (TiSiW)N) on the surface side of the first layer or the third layer, which is the layer closest to the tool surface. This surface layer is mainly composed of Ti and contains Si, which further improves the oxidation resistance and thermoplastic deformation resistance of the coating layer, and contains W, which further improves the high-temperature strength and wear resistance of the coating layer.

[0056] The average thickness of this surface layer is preferably 0.1 μm or more and 4.0 μm or less. The reason for setting the average thickness within this range is, for example, to further improve the chipping resistance, fracture resistance, and wear resistance of the coating layer under high-load cutting conditions. A more preferred range for this average thickness is 0.1 μm or more and 2.0 μm or less.

[0057] Here, the average composition of this surface layer (fourth layer) is: Formula: (Ti 1-α-β Si α W β )N, it is preferable that 0.01≦α≦0.20 and 0.01≦β≦0.10.

[0058] The reason for specifying this range for α is that if it is less than 0.01, the improvement in the oxidation resistance and thermoplastic deformation resistance of the surface layer is small, while if α exceeds 0.20, lattice strain increases, making the surface layer more susceptible to self-destruction under high-load cutting conditions. The reason for setting β within this range is that if it is less than 0.01, the effect of the surface layer in improving strength at high temperatures is small, while if β exceeds 0.10, lattice distortion increases, reducing the chipping resistance of the surface layer during high-load cutting.

[0059] Furthermore, the W content has a repeated change in which the average distance between adjacent maximum and minimum values ​​is 1 nm or more and 100 nm or less, and the average value of the maximum values ​​of the W content is W max When set to 1.0 <W max / β≦2.0, and the average value of the minimum W content is W min When 0.0≦Wmin It is preferable that / β<1.0, where β is the average composition β of W in the formula of the surface layer (fourth layer).

[0060] The reason why the average spacing between adjacent maximum and minimum values ​​is preferably 1 nm or more and 100 nm or less is that if the average spacing is less than 1 nm, the W content will change abruptly, causing localized large lattice strain in the surface layer and reducing the chipping resistance of the coating layer, while if it exceeds 100 nm, the area with a high W content, i.e., large lattice strain in the surface layer, will become wider, making chipping more likely to occur from that area and reducing the chipping resistance of the coating layer.The average spacing of repeated changes is more preferably 5 nm or more and 50 nm or less.

[0061] In addition, the ratio of the average value of the maximum W content to β, W max / β and the ratio of the average value of the minimum value to β W min The reason for setting / β in the above range is that W max / β is greater than 1.0, and W min If / β is less than 1.0, the lattice strain in the surface layer can be reduced by repeatedly changing the composition. max If / β exceeds 2.0, the range of change in the composition becomes large, and a sudden change in the W content occurs, which reduces the chipping resistance of the surface layer. max / β and W min / β is 1.2 <W max / β≦2.0, 0.0≦W min / β<0.8 is more preferred.

[0062] Regarding the repeated change in W content, the average interval, W max and W min The determination of is similar to the repeated change of the Si content explained based on Fig. 2. That is, Si in Fig. 2 is replaced with W.

[0063] (3) Middle class In this embodiment, an intermediate layer (fifth layer) having a predetermined composition and structure of a composite nitride of Al, Cr, Ti, Si, and W (hereinafter, may be represented by (AlCrTiSiW)N) may be further provided between the first layer on the surface side of the coating tool layer of the laminate layer or between the third layer and the surface layer (fourth layer). In this embodiment, the presence of the intermediate layer is optional and not essential. That is, the intermediate layer may or may not be present. When this intermediate layer is present, the chipping resistance, defect resistance, and wear resistance of the coating layer are further improved.

[0064] The average thickness of this intermediate layer is preferably 0.1 μm or more and 2.0 μm or less. The reason for setting the average thickness within this range is that if the average thickness is less than 0.1 μm, the effect of improving the adhesion to the surface layer, the first layer, and the third layer cannot be sufficiently obtained. On the other hand, if it exceeds 2.0 μm, the lattice strain in the intermediate layer becomes large, and conversely, the adhesion to each adjacent layer decreases. For this average thickness, a more preferable range is 0.1 μm or more and 1.0 μm or less.

[0065] Here, the average composition of this intermediate layer is Formula: (Al 1-k-l-m-n Ti k Cr l Si m W n )N, when expressed, it is preferably 0.20 ≦ k ≦ 0.65, 0.10 ≦ l ≦ 0.35, 0.00 < m ≦ 0.15, 0.00 < n ≦ 0.05.

[0066] Next, the reason for defining this composition range will be explained. Al, which is a component constituting the intermediate layer, improves the high-temperature hardness and heat resistance of the intermediate layer. Ti improves the high-temperature hardness and high-temperature strength. Cr improves the high-temperature strength and lubricity of the intermediate layer. Si improves the oxidation resistance and thermoplastic deformation resistance of the intermediate layer. Furthermore, by containing W, the high-temperature strength of the intermediate layer is further improved, and the wear resistance is improved.

[0067] If the Ti content is less than 0.20, the intermediate layer will not have sufficient high-temperature hardness and strength, and the Al content will be relatively high, which will lead to the formation of hexagonal crystals in the intermediate layer and reduce the adhesion between the first layer, the third layer, and the surface layer. On the other hand, if the Ti content exceeds 0.65, the contents of other components will be relatively low, which will prevent the intermediate layer from having sufficient wear resistance. A more preferable range for the Ti content is 0.20 or more and 0.50 or less.

[0068] If the Cr content is less than 0.10, the intermediate layer will not have sufficient high-temperature strength and lubricity, while if it exceeds 0.35, the contents of other components will be relatively low, making it impossible to obtain sufficient wear resistance in the intermediate layer. A more preferable range for the Cr content is 0.10 or more and 0.25 or less.

[0069] If the Si content is 0.00 (no Si is contained), the intermediate layer will not have sufficient oxidation resistance and plastic deformation resistance, and will not have sufficient affinity with the first and third layers, resulting in reduced adhesion. On the other hand, if the Si content exceeds 0.15, lattice distortion within the intermediate layer will increase, reducing adhesion with the first, third, and surface layers. A more preferred range for the Si content is 0.03 to 0.15.

[0070] If the W content is 0.00 (no W is contained), the high-temperature strength of the intermediate layer is insufficient, while if it exceeds 0.05, the lattice strain in the intermediate layer increases, resulting in a decrease in adhesion to the surface layer. A more preferred range for the W content is 0.01 or more and 0.05 or less.

[0071] In addition, it is preferable that the intermediate layer has a repeated change in the Si content such that the interval between the adjacent maximum and minimum values ​​is 1 nm or more and 100 nm or less. max When this is done, it becomes 1.0. <Sim max / m≦2.0, and the average value of the minimum values ​​of the Si content is Sim min When this is the case, 0.0≦Sim min It is preferable that / m<1.0.

[0072] The reason why the average spacing between adjacent maximum and minimum values ​​is preferably 1 nm or more and 100 nm or less is as follows: If the average spacing is less than 1 nm, the Si content changes abruptly, making the coating layer more susceptible to chipping and preventing a sufficient improvement in adhesion between the surface layer and the first and third layers; on the other hand, if the spacing exceeds 100 nm, the region with a high Si content, i.e., large lattice distortion, becomes wider, making chipping more likely to occur from that region, preventing a sufficient improvement in adhesion. The range of the average spacing of repeated changes is more preferably 5 nm or more and 50 nm or less.

[0073] In addition, the ratio of the average value of the maximum Si content to m, Sim max / m and the ratio of the average value of the minimum value to m Sim min The reason for setting / m in the above range is that Sim max / m exceeds 1.0, Sim min If / m is less than 1.0, the Si content will change repeatedly, but max If / m exceeds 2.0, the change in the Si content becomes large, and the sudden change in the Si content causes a decrease in the chipping resistance of the coating layer.

[0074] The crystal structure of the crystal grains constituting the fourth and fifth layers is preferably an NaCl-type face-centered cubic structure. However, as with the first, second, and third layers, these layers may contain an unavoidable (unintentional) amount of crystal grains having a crystal structure other than the NaCl-type face-centered cubic structure.

[0075] In the embodiment shown in FIG. 3, a third layer and an intermediate layer (fifth layer) are shown, but this embodiment is not limited to this, and the third layer and / or the intermediate layer (fifth layer) may not be present.

[0076] 2.Base The material and shape of the substrate are the same as those described in the embodiment shown in FIG.

[0077] 3. Manufacturing method The first, second and third layers are the same as those described in the embodiment shown in FIG.

[0078] (1) Surface layer (4th layer) The surface layer can be formed by, for example, the following PVD method. That is, arc discharge is simultaneously generated between two Ti-Si-W alloy targets with different compositions and an anode electrode, and the film formation conditions are adjusted to form a film with a repeatedly changed W content. Furthermore, as with the second layer, by generating a single arc using a single Ti—Si—W alloy target and adjusting the film formation conditions, it is possible to form a layer with a repeatedly changing W content.

[0079] (2) Middle class (5th class) The intermediate layer can be formed by, for example, the following PVD method. That is, the films can be formed by simultaneously generating arc discharges between an Al-Cr-Si alloy target and a Ti-Si-W alloy target and an anode electrode under predetermined film formation conditions.

[0080] The target combination is not limited to a combination of an Al-Cr-Si alloy target and a Ti-Si-W alloy target, and may be a combination of an Al-Cr alloy target and a Ti-Si-W alloy target, or a combination of three or more types, such as an Al-Cr-Si alloy target, an Al-Cr alloy target and a Ti-Si-W alloy target, as long as it provides the desired structure of the intermediate layer.

[0081] III. Measurement Method 1. Measurement of average composition, interface and average thickness of each layer The content of the components constituting each layer is determined by measuring the longitudinal cross section using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS), and averaging the measured values.

[0082] Here, the substrate surface refers to the reference line of the interface roughness between the substrate and the coating layer in the cross-sectional observation image. That is, when the substrate has a flat surface like an insert, elemental mapping is performed using EDS on the longitudinal cross section, and the interface between the first layer and the substrate is determined by performing known image processing on the obtained elemental map. The average line is arithmetically calculated for the roughness curve of the interface between the first layer and the substrate, and this is defined as the substrate surface. The direction perpendicular to this average line is defined as the direction perpendicular to the substrate (thickness direction of the coating layer). Even when the substrate has a curved surface like a drill, if the tool diameter is sufficiently large compared to the thickness of the coating layer, the interface between the coating layer and the substrate in the measurement area will be approximately flat, and the substrate surface can be determined using a similar method. That is, for example, in the case of a drill, elemental mapping is performed using EDS on the longitudinal cross section of the coating layer in a cross section perpendicular to the axial direction, and the interface between the coating layer and the substrate is determined by performing known image processing on the obtained elemental map. The average line is arithmetically calculated for the roughness curve of the interface between the coating layer and the substrate, and this is defined as the substrate surface. The direction perpendicular to this average line is defined as the direction perpendicular to the surface of the substrate (thickness direction of the coating layer).

[0083] The measurement area in the longitudinal section is set to include the entire thickness area of ​​the coating layer. Considering the thickness of the coating layer and the accuracy of thickness measurement, it is preferable to observe and measure multiple fields of view (e.g., three fields of view) with a field of view of about 10 μm × 10 μm.

[0084] Furthermore, since the second layer, surface layer (fourth layer), and intermediate layer (fifth layer) have repeated changes in Si content or W content, the Si content or W content in each layer is measured in multiple analysis lines (for example, five lines) along the direction perpendicular to the surface of the substrate (thickness direction of the coating layer), the Si content and W content are detected, and the position where each is 1 atomic % (i.e., the position where b = 0.01 or β = 0.01) is defined as the interface with the adjacent layer, and the thickness is calculated for each of the multiple lines, and the calculated thicknesses are averaged to determine the average thickness. Since there is only one third layer, the thicknesses measured in the multiple analysis lines for this layer are averaged to determine the average thickness. The average content of elements constituting each layer is calculated by averaging the results of line analysis in each layer.

[0085] 2. Confirmation of crystal grains with NaCl-type face-centered cubic structure The crystal structures of the first, second, third, surface (fourth) and intermediate (fifth) layers were identified by electron diffraction using a transmission electron microscope (TEM), and were confirmed to be NaCl-type face-centered cubic structures. [Example]

[0086] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0087] Example A Examples corresponding to the embodiment of a coated tool having a coating layer including a laminate layer having a first layer, a second layer, and a third layer as shown in FIG. 1 (including an example in which there is no third layer and the first layer is the outermost layer of the laminate layer) will be described.

[0088] A drill substrate was prepared as the substrate. Specifically, Co powder, VC powder, TaC powder, NbC powder, Cr3C2 powder, and WC powder, all with average particle sizes of 0.5 to 5 μm, were prepared as raw material powders and blended as shown in Table 1. Wax was added and the mixture was wet mixed in a ball mill for 72 hours, dried under reduced pressure, and then press-molded at a pressure of 100 MPa. These green compacts were sintered and then formed into sintered round bars for forming substrates with a diameter of 6 mm. Next, drill substrates 1 to 3 made of WC-based cemented carbide were produced by grinding. Each drill substrate had a groove-forming portion with dimensions of 6 mm in diameter and 48 mm in length and a two-flute shape with a helix angle of 30 degrees.

[0089] [Table 1]

[0090] Next, film formation was carried out as follows. The drill bases 1 to 3 were subjected to the following treatments (1) to (5) in order using the arc ion plating apparatus shown in FIGS.

[0091] (1) Drill substrates 1 to 3 were ultrasonically cleaned in acetone and, in a dried state, mounted along their outer peripheries at positions radially spaced a predetermined distance from the central axis on a rotary table in an arc ion plating device.

[0092] (2) Evacuate the inside of the device and -2 While maintaining a vacuum of 0.2 Pa or less, the inside of the apparatus was heated to 500°C using a heater, and then the pressure was set to 0.2 Pa in an Ar gas atmosphere. A DC bias voltage of -200 V was applied to the drill substrate rotating on the rotating table, and the surface of the drill substrate was bombarded with argon ions for 20 minutes.

[0093] (3) To create a nitrogen atmosphere as shown in Table 2, nitrogen gas was introduced into the apparatus as a reactive gas and maintained at a predetermined temperature. The rotary table was controlled to rotate at a predetermined speed. A predetermined DC bias voltage was applied to the drill base rotating on the rotary table. A predetermined current was also applied between the Al-Cr alloy target and the anode electrode to generate an arc discharge, and a first layer having a predetermined average thickness was deposited.

[0094] (4) As shown in Table 2, a predetermined current was passed between the Al-Cr alloy target and the anode electrode to generate an arc discharge, and simultaneously a predetermined current was passed between the Al-Cr-Si alloy target and the anode electrode to generate an arc discharge, thereby forming a second layer of a predetermined average thickness on the surface of the first layer formed as described above, in which the Si content was repeatedly changed by simultaneous film formation from two types of alloy targets.

[0095] (5) The steps (3) and (4) were repeated to stack a predetermined number of first and second layers, and in certain examples, a third layer was formed on the tool surface side, thereby obtaining Examples 1 to 6 shown in Table 4. Here, Examples 3 and 5 did not have a third layer formed.

[0096] When the composition of the third layer was different from that of the first layer, the target designated by component number 9 in FIGS. 6 and 7 was used as the Al—Cr alloy target for depositing the third layer.

[0097] In the film formation steps (1) to (5), by adjusting the arc current value, the partial pressure of nitrogen gas as a reactive gas, the bias voltage, the film formation temperature, and the like among the film formation conditions for the first, second, and third layers, the half width of the 111 diffraction line of the crystal grains of the NaCl type face-centered cubic structure of the laminate layer formed simultaneously from the Al-Cr alloy target and the Al-Cr-Si alloy target, I 111 / I 200 The values ​​were controlled to be predetermined values, and the values ​​are shown in Table 4.

[0098] The results of X-ray diffraction measurement for Example 4 are shown in Figure 4. X-ray diffraction was performed using Cu-Kα radiation using the 2θ / θ focusing method under the following conditions: a measurement range (2θ) of 30 to 80 degrees, a scan step of 0.015 degrees, and a measurement time per step of 0.23 seconds / step. In Figure 4, the 111 diffraction line representing the first, second, and third layers can be observed around 38 degrees, and the 200 diffraction line representing the first, second, and third layers can be observed around 44 degrees. The peaks around 36 degrees and 48 degrees are due to hexagonal WC. The measurement conditions for the X-ray diffraction measurement for Example 4 are merely exemplary, and other measurement conditions may be used as long as the 111 diffraction line and 200 diffraction line can be observed.

[0099] For comparison, a laminate layer including a first layer and a second layer was formed on drill substrates 1 to 3 under the conditions shown in Table 3, as in Examples 1 to 6, and a third layer was formed in specific comparative examples, thereby producing comparative coated tools (referred to as "Comparative Examples") 1 to 6 shown in Table 5. Here, the third layer was not formed in Comparative Examples 3 and 6.

[0100] Repeated changes in the average thickness, average composition, and Si content of each layer in the examples and comparative examples (Si max , Si min The average distance between adjacent maximum and minimum values ​​was determined by the method described above. It was also confirmed by the method described above that the first to third layers contained crystal grains with an NaCl-type face-centered cubic structure. In all of the Examples and Comparative Examples, no diffraction lines indicating a crystal structure other than the NaCl-type face-centered cubic structure were observed, and no crystal grains having a crystal structure other than the NaCl-type face-centered cubic structure were present in excess of an unavoidable amount.

[0101] The second layer in Comparative Example 2 was formed using a single Al-Cr-Si alloy target. The absolute values ​​of the equipment temperature and bias voltage were higher than those in the Example, and the N2 gas pressure was lower. This created an environment in which repeated changes in the Si content were less likely to occur, and a repeated structure of Si composition was not formed in the second layer. In other words, the Si content along the thickness direction of the second layer was nearly uniform, and no repeated changes in the content were formed (see Table 5). In this respect, the layer structure of the second layer differs from that of the Example tool.

[0102] [Table 2]

[0103] [Table 3]

[0104] [Table 4]

[0105] [Table 5]

[0106] Next, the following cutting test 1 was carried out on Examples 1 to 6 and Comparative Examples 1 to 6 to evaluate the properties as coated tools.

[0107] Cutting test 1 Test content: Wet drilling and cutting test Drill shape: 6mm diameter, two-flute carbide drill Workpiece - Shape: Carbon steel S50C plate material Cutting speed: 110 m / min. Feed: 0.25 mm / rev Hole depth: 25 mm (blind hole drilling)

[0108] The evaluation of this cutting test 1 was as follows, and the results are shown in Table 6. In other words, drilling until the flank wear width of the cutting edge reaches 0.3 mm, or until the cutting edge reaches the end of its life due to chipping, fracture, or breakage. Number of times The cutting edge wear was measured and the cutting edge wear state was observed. Machining was continued up to 4000 holes, and for those that had not reached the end of their life at this time, the flank wear width was measured after 4000 holes had been machined.

[0109] [Table 6]

[0110] In the above-mentioned cutting test 1 (wet drilling test), the cutting edge is in continuous contact with the workpiece during the machining of each hole, and when the next hole is drilled after one hole is finished, the cutting edge temporarily loses contact with the workpiece. Therefore, this can be said to be a high-load cutting process that includes continuous machining and intermittent machining. The results in Table 6 show that the tools of the examples have less wear, a longer life, and improved wear resistance and chipping resistance in high-load cutting compared to the tools of the comparative examples. In this example, the substrate is shaped like a drill, but the above-mentioned effects can be obtained regardless of the substrate shape as long as the cutting edge of the tool is subjected to the same type of load. For example, even if an insert-shaped substrate is used, it can be said that similar improvements in cutting performance can be achieved in high-load cutting, including continuous and intermittent cutting, such as machining of round bars with holes or grooves.

[0111] Example B Examples corresponding to an embodiment of a coated tool having a coating layer having a laminate layer including a first layer, a second layer, a third layer, a surface layer (fourth layer), and an intermediate layer (fifth layer) as shown in FIG. 3 will be described (including examples in which the third layer and / or the fifth layer is absent).

[0112] The same substrate as in Example A (shown in Table 1) was prepared, and the film formation conditions for the first to third layers were the same as in Example A and were as shown in Table 2. After the first to third layers were formed, an intermediate layer (fifth layer) was selectively formed as described below, and then a surface layer (fourth layer) was formed, thereby obtaining Examples 11 to 24 shown in Tables 11 and 12. Here, in Examples 17 to 24, only the first and second layers, or only the first, second and third layers, are embodiments of the present invention.

[0113] The intermediate layer (fifth layer) was formed under the deposition conditions shown in Table 7 by passing a predetermined current between an Al-Cr-Si alloy target shown in Table 7 and an anode electrode to generate an arc discharge, and simultaneously passing a predetermined current from a Ti-Si-W alloy target shown in Table 7 between an anode electrode to generate an arc discharge. This intermediate layer (fifth layer) showed repeated changes in Si content. In Examples 23 and 24, no intermediate layer was formed, and a surface layer (fourth layer) was formed directly on the first or third layer.

[0114] The surface layer (fourth layer) was formed by simultaneously generating an arc discharge between one or two Ti-Si-W alloy targets having different compositions shown in Table 8 and an anode electrode under the film formation conditions shown in Table 8. The surface layer (fourth layer) had a W content that repeatedly changed.

[0115] In the deposition of each of the layers, the half width of the 111 diffraction line and the I 111 / I 200 was controlled to a predetermined value, and the value is shown in Table 11.

[0116] On the other hand, for comparison, the first to third layers (including the first layer being the most superficial layer of the laminate layer, not the third layer) were formed on the drill substrates 1 to 3 under the deposition conditions shown in Table 3 in the same manner as in Comparative Examples 1 to 6. Further, coating layers having a surface layer (fourth layer) and an intermediate layer (fifth layer) were formed under the conditions shown in Tables 9 and 10, respectively, to obtain the results shown in Tables 13 and 14 for Comparative Example 1. 2 ~16 were produced.

[0117] The results of X-ray diffraction measurement for Example 14 are shown in Figure 5. In addition to the diffraction lines described in Figure 4, the 111 diffraction line of the surface layer (fourth layer) was observed between 36 and 37 degrees, and the 200 diffraction line of the same layer was observed between 42 and 43 degrees.

[0118] The average thickness, average composition, repeated changes in Si content, and repeated changes in W content of each layer were determined by the methods described above, as explained in Example A. It was also confirmed by the methods described above that the first to fifth layers contained crystal grains with an NaCl-type face-centered cubic structure.

[0119] In the surface layer (fourth layer) in Example 20 and Comparative Example 14, the W content along the thickness direction of the surface layer (fourth layer) was almost equal, and no repeated change in the W content was formed. Example 20 The surface layer (fourth layer) of Comparative Example 14 was formed using a single type of Ti-Si-W alloy target, similar to the surface layers (fourth layer) of Examples 11, 12, 14, and 16. However, compared to these Examples, the absolute values ​​of the equipment temperature and bias voltage were larger, and the N2 gas pressure was smaller, creating an environment in which repeated changes in the W content were less likely to occur, and no repeated changes in the W content were observed.

[0120] [Table 7]

[0121] [Table 8]

[0122] [Table 9]

[0123] [Table 10]

[0124] [Table 11]

[0125] [Table 12]

[0126] [Table 13]

[0127] [Table 14]

[0128] Next, Examples 11 to 24 and Comparative Example 1 2 Cutting test 1 was carried out on the coated tools 1 to 16 under the same conditions as in Example A, and the properties as coated tools were evaluated. The results are shown in Table 15.

[0129] [Table 15]

[0130] The results in Table 15 show that when comparing Examples 2 to 6 and Examples 12 to 16, which have only Layers 1 to 3 formed under the same conditions, the wear resistance and chipping resistance during heavy-load cutting are further improved by combining Layers 1 to 3 with Layers 4 and 5. Furthermore, when comparing Example 1 with Example 11, the flank wear volume of Example 11 is smaller, even though the average thickness of the coating layer in Example 1 is larger (thicker) than in Example 11. This suggests that the wear resistance is improved by combining Layers 4 and 5.

[0131] Next, Examples 11 to 16 and Comparative Example 1 2 Cutting test 2 similar to that in Example A was carried out on samples 1 to 16 to evaluate their properties as coated tools. The results are shown in Table 16.

[0132] Cutting test 2 Test content: Wet drilling and cutting test Drill shape: 6mm diameter, two-flute carbide drill Workpiece - Shape: Carbon steel S50C plate material Cutting speed: 125 m / min. Feed: 0.25 mm / rev Hole depth: 30 mm (through hole drilling)

[0133] [Table 16]

[0134] Cutting Test 2 (wet drilling test) was a high-load cutting test similar to Cutting Test 1 of Example A, but because it involved through-hole drilling at a faster cutting speed and with a greater number of impacts, it could be said to be a cutting test with even higher loads than Cutting Test 1 of Example A. The results in Table 16 show that the tool of Example B has a lower wear amount and a longer life than the comparative tool, and exhibits high wear resistance and chipping resistance even under cutting loads higher than Cutting Test 1 of Example A. Like Example A, Example B uses a drill substrate. However, similar effects can be obtained regardless of the substrate shape as long as the cutting edge is subjected to the same type of load. For example, even when an insert is used as the substrate, it can be said that similar effects can be obtained in high-load cutting, including continuous and intermittent cutting, such as drilling a round bar with a hole or a round bar with a groove.

[0135] The above-disclosed embodiments are merely illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not by the above-disclosed embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0136] 1 Base 2 1st layer 3 2nd layer 4 3rd layer 5 Surface layer (4th layer) 6. Middle layer (5th layer) 7 Laminate Layer 8 Anode electrode 9. Ti-Si-W alloy target for forming the fourth layer (or Al-Cr alloy target for forming the third layer) 10 Ti-Si-W alloy target for forming the fourth layer 11 Al-Cr-Si alloy target for depositing the second and fifth layers 12 Ar-Cr alloy target for first layer deposition 13 Heater 14 Rotating table 15 Base 16 Reaction gas inlet 17 Exhaust gas outlet 18 Arc Power Supply 19 Bias power supply

Claims

1. A surface-coated cutting tool having a substrate and a coating layer on a surface of the substrate, 1) The coating layer has an average thickness of 0.5 μm or more and 8.0 μm or less, and has a laminate layer in which one or more first layers and one or more second layers are alternately laminated, 2) the layer of the laminate closest to the substrate and the layer closest to the surface of the tool are both the first layer; 3) The first layer has an average thickness of 0.1 μm or more and 2.0 μm or less, and (Al １－ｘ Cr ｘ )N (0.20≦x≦0.60), 4) The second layer has an average thickness of 0.1 μm or more and 2.0 μm or less, and (Al １－ａ－ｂ Cr ａ Si ｂ )N (0.20≦a≦0.60, 0.01≦b≦0.20), and the Si content repeatedly changes such that the average distance between the maximum and minimum values ​​adjacent to each other in the direction perpendicular to the surface of the substrate is 1 nm or more and 100 nm or less, and the average value of the maximum values ​​of the Si content is ｍａｘ However, 1.0<Si ｍａｘ / b≦2.0, and the average value Si of the minimum values ​​of the Si content ｍｉｎ However, 0.0≦Si ｍｉｎ / b<1.0, 5) The first layer and the second layer both have crystal grains with an NaCl-type face-centered cubic structure, 6) When the X-ray diffraction peaks of the first layer and the second layer are summarized, the half-width of the diffraction peak of the 111 diffraction ray is 0.1 degree or more and 1.0 degree or less, and the diffraction peak intensity of the diffraction ray is I １１１ , the diffraction peak intensity of the 200 diffraction line is I ２００ When I １１１ / I ２００ is greater than 1.0 and less than 5.0; A surface-coated cutting tool characterized by:

2. The first layer of the laminate layer closest to the surface of the tool is replaced with a layer having an average composition of (Al １－ｙ Cr ｙ 2. The surface-coated cutting tool according to claim 1, wherein the third layer has an average thickness of 0.3 μm or more and 4.0 μm or less, and is larger in average thickness than the first layer other than the first layer of the laminate layer.

3. The laminate layer has an average thickness of 0.1 μm or more and 4.0 μm or less on the tool surface side of the first layer or the third layer closest to the tool surface side, and the average composition is (Ti １－α－β Si α W β ) N (0.01≦α≦0.20, 0.01≦β≦0.10), The W content has repeated changes such that the average distance between adjacent maximum and minimum values ​​is 1 nm or more and 100 nm or less, and the average value W of the maximum values ​​of the W content ｍａｘ is 1.0<W ｍａｘ / β≦2.0, and the average value W of the minimum value of the W content ｍｉｎ is 0.0≦W ｍｉｎ 3. The surface-coated cutting tool according to claim 1, wherein the surface layer has a β / β<1.

0.

4. Between the first layer or the third layer of the laminate layer that is closest to the surface of the tool and the surface layer, the average thickness is 0.1 μm or more and 2.0 μm or less, and the average composition is (Al １－ｋ－ｌ－ｍ－ｎ Ti ｋ Cr ｌ Si ｍ W ｎ ) N (0.20≦k≦0.65, 0.10≦l≦0.35, 0.00<m≦0.15, 0.00<n≦0.05); The Si content has repeated changes such that the average distance between adjacent maximum and minimum values ​​is 1 nm or more and 100 nm or less, and the average value Sim of the maximum values ​​of the Si content ｍａｘ However, 1.0<Sim ｍａｘ / m≦2.0, and the average value of the minimum values ​​of the Si content is ｍｉｎ However, 0.0≦Sim ｍｉｎ 4. The surface-coated cutting tool according to claim 3, further comprising an intermediate layer in which / m<1.0.

Images