Cutting Tools

Abstract

A cutting tool comprising a substrate and a coating disposed on the substrate, the coating including a hard particle layer, the hard particle layer including a plurality of hard particles including titanium, silicon, carbon, and nitrogen, the hard particle layer including a first region and a second region, the first region being a region sandwiched between a first main surface of the hard particle layer on the substrate side and a virtual surface S1 at a distance of 0.5 μm from the first main surface to the hard particle layer side, the second region being a region sandwiched between a second main surface of the hard particle layer opposite to the first main surface and a virtual surface S2 at a distance of 0.5 μm from the second main surface to the hard particle layer side, and the first region having a composition of Ti (1-Xb) S Xb CN, and the composition of the second region is Ti (1-Xs) S Xs CN, and Xs and Xb are Xb-Xs≧0.01 and 0

Description

Technical Field

[0001] The present disclosure relates to a cutting tool.

Background Art

[0002] Conventionally, in order to improve the wear resistance of a cutting tool, a cutting tool having a TiSiCN film formed on a substrate has been developed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The cutting tool of the present disclosure is a cutting tool including a substrate and a film disposed on the substrate, the film includes a hard particle layer, the hard particle layer is composed of a plurality of hard particles made of titanium, silicon, carbon, and nitrogen, the hard particle layer includes a first region and a second region, the first region is a region sandwiched between a first main surface on the substrate side of the hard particle layer and a virtual surface S1 whose distance from the first main surface to the hard particle layer side is 0.5 μm, the second region is a region sandwiched between a second main surface on the side opposite to the first main surface of the hard particle layer and a virtual surface S2 whose distance from the second main surface to the hard particle layer side is 0.5 μm, the composition of the first region is Ti (1-Xb) Si Xb CN, the composition of the second region is Ti (1-Xs) Si Xs CN, the Xs and Xb satisfy the relationship of Xb - Xs ≧ 0.01 and 0 < Xs < Xb ≦ 0.10, the hard particles have a cubic crystal structure, In the hard particles, the concentration of silicon changes periodically along a first direction from the first main surface to the second main surface. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic view showing an example of a cross section of a cutting tool according to a first embodiment. [Diagram 2] FIG. 2 is a schematic view showing another example of a cross section of the cutting tool according to the first embodiment. [Diagram 3] FIG. 3 is a schematic view showing another example of a cross section of the cutting tool according to the first embodiment. [Figure 4] FIG. 4 is a schematic view showing another example of a cross section of the cutting tool according to the first embodiment. [Diagram 5] FIG. 5 is a schematic view showing another example of a cross section of the cutting tool according to the first embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view of an example of a CVD apparatus used in manufacturing the cutting tool according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] [Problem that this disclosure aims to solve] The cutting tool of Patent Document 1 has a hard TiSiCN film and is therefore excellent in wear resistance. However, when the cutting tool of Patent Document 1 is used to mill die steel, cracks may occur in the film, shortening the tool life. For this reason, there is a demand for a cutting tool that can have a long tool life, particularly in the milling of die steel.

[0007] Therefore, an object of the present disclosure is to provide a cutting tool that has a long tool life, particularly when used in milling of die steel.

[0008] [Effects of this disclosure] According to the present disclosure, it is possible to provide a cutting tool that can have a long tool life, particularly even when used for milling die steel.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. (1) The cutting tool of the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, wherein the coating includes a hard particle layer, the hard particle layer is composed of a plurality of hard particles made of titanium, silicon, carbon, and nitrogen, the hard particle layer includes a first region and a second region, the first region is a region sandwiched between a first main surface on the substrate side of the hard particle layer and a virtual surface S1 whose distance from the first main surface toward the hard particle layer side is 0.5 μm, the second region is a region sandwiched between a second main surface on the opposite side of the first main surface of the hard particle layer and a virtual surface S2 whose distance from the second main surface toward the hard particle layer side is 0.5 μm, the composition of the first region is Ti (1-Xb) Si Xb CN, the composition of the second region is Ti (1-Xs) Si Xs CN, wherein Xs and Xb satisfy the relationship of Xb - Xs ≧ 0.01 and 0 < Xs < Xb ≦ 0.10, the hard particles have a cubic crystal structure, and in the hard particles, the concentration of silicon periodically changes along a first direction from the first main surface toward the second main surface, which is a cutting tool.

[0010] According to the present disclosure, it is possible to provide a cutting tool that can have a long tool life, particularly even when used for milling die steel.

[0011] (2) In the above (1), the hard particle layer may have a columnar structure. This makes the hard particle layer resistant to stress in the shear direction and improves wear resistance. Furthermore, the hard particle layer has fewer grain boundaries in the direction perpendicular to the film thickness, which reduces the number of fracture origins and improves chipping resistance.

[0012] (3) In the above (1) or (2), the ratio L1 / T1 of the length L1 of the hard particles along the first direction to the thickness T1 of the hard particle layer may be 0.3 or more. This makes the hard particle layer resistant to stress in the shear direction and improves wear resistance. Furthermore, the hard particle layer has fewer grain boundaries in the direction perpendicular to the film thickness, so that the number of fracture origins is reduced and chipping resistance is improved.

[0013] (4) In any one of (1) to (3) above, the periodic width of the silicon concentration along the first direction in the hard particles may be 3 nm or more and 20 nm or less, which maintains strain in the hard particles, further suppresses crack growth in the coating, and further improves the chipping resistance of the cutting tool.

[0014] (5) In any one of the above (1) to (4), the hard particle layer may have an average thickness of 2 μm or more and 15 μm or less, thereby further improving the tool life.

[0015] (6) In any of (1) to (5) above, the coating includes a base layer provided between the substrate and the hard particle layer, The underlayer may include at least one selected from the group consisting of a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, and an Al2O3 layer.

[0016] By disposing a TiN layer, a TiC layer, a TiCN layer, or a TiBN layer as the underlayer, the adhesion between the substrate and the coating can be improved. Also, by using an Al2O3 layer as the underlayer, the oxidation resistance of the coating can be improved.

[0017] (7) In any of (1) to (6) above, The coating includes a surface layer provided on an outermost surface of the coating, The surface layer may be a TiN layer or an Al2O3 layer.

[0018] This improves the thermal cracking resistance and abrasion resistance of the coating.

[0019] [Details of the embodiment of the present disclosure] In this disclosure, an expression in the form "A to B" means the upper and lower limits of a range (i.e., A or more and B or less). When no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0020] In the present disclosure, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is intended to include any conventionally known atomic ratio, and should not necessarily be limited to only those within the stoichiometric range.

[0021] In the present disclosure, when one or more numerical values ​​are described as the lower limit and the upper limit of a numerical range, the combination of any one numerical value described as the lower limit and any one numerical value described as the upper limit is also disclosed. For example, when a1 or more, b1 or more, and c1 or more are described as the lower limit, and a2 or less, b2 or less, and c2 or less are described as the upper limit, a1 or more and a2 or less, a1 or more and b2 or less, a1 or more and c2 or less, b1 or more and a2 or less, b1 or more and b2 or less, b1 or more and c2 or less, c1 or more and a2 or less, c1 or more and b2 or less, and c1 or more and c2 or less are disclosed.

[0022] In order to develop a cutting tool that can have a long tool life even when milling die steel, the inventors performed milling of die steel using a conventional cutting tool and observed the fracture morphology of the coating.

[0023] It was confirmed that when die steel was milled using the cutting tool of Patent Document 1, film cracks occurred on the tool surface, which caused the film to break. Milling of die steel is a process in which wear of the flank and thermal cracks on the rake face are prominent. Thermal cracks occur when the tool surface side is repeatedly heated by contact with the workpiece and cooled during idling. In particular, when the toughness of the tool surface side is low, the occurrence of cracks becomes prominent. The TiSiCN film of the cutting tool of Patent Document 1 is highly hard and therefore has excellent wear resistance, but the toughness of the film is insufficient for milling of die steel. For this reason, it is presumed that film cracks occur on the tool surface in Patent Document 1.

[0024] As a result of intensive research based on the above findings, the present inventors have obtained a cutting tool that has a long tool life even when used in milling of die steel. Specific examples of the cutting tool of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference symbols represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed to clarify and simplify the drawings, and do not necessarily represent actual dimensional relationships.

[0025] [Embodiment 1: Cutting tool] A cutting tool according to an embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") will be described with reference to Figs. 1 to 5. The cutting tool 1 of the present embodiment has: A cutting tool comprising a substrate 10 and a coating 15 disposed on the substrate 10, The coating 15 includes a hard particle layer 11, The hard particle layer 11 is made of a plurality of hard particles made of titanium, silicon, carbon and nitrogen, The hard particle layer 11 includes a first region A1 and a second region A2, The first region A1 is a region sandwiched between a first main surface Q1 of the hard particle layer 11 on the substrate 10 side and a virtual surface S1 that is 0.5 μm away from the first main surface Q1 toward the hard particle layer 11 side. The second region A2 is a region sandwiched between the second main surface Q2 of the hard particle layer 11 opposite to the first main surface Q1 and a virtual surface S2 whose distance from the second main surface Q2 to the hard particle layer 11 side is 0.5 μm. The composition of the first region A1 is Ti (1-Xb) Si Xb CN, and The composition of the second region A2 is Ti (1-Xs) Si Xs CN, and Xs and Xb satisfy the relationships of Xb - Xs ≥ 0.01 and 0 < Xs < Xb ≤ 0.10. The hard particles have a cubic crystal structure. In the hard particles, along the first direction from the first main surface to the second main surface, the concentration of silicon changes periodically, and it is the cutting tool 1.

[0026] The cutting tool of this embodiment can have a long tool life especially when used for milling die steel. Although the reason for this is not clear, it is speculated to be as follows (i) to (iii).

[0027] (i) In the cutting tool of this embodiment, the coating includes a hard particle layer composed of a plurality of hard particles made of titanium, silicon, carbon, and nitrogen. The hard particle layer has high hardness. Therefore, the cutting tool having the hard particle layer is excellent in wear resistance. Therefore, the cutting tool can have a long tool life.

[0028] (ii) In the cutting tool of this embodiment, the hard particle layer includes a first region on the base material side and a second region on the surface side. The silicon content of the second region is smaller than the silicon content of the first region, and the second region is more excellent in toughness than the first region. For this reason, even when the cutting tool having the hard particle layer is used for milling die steel, the generation of cracks on the surface side of the hard particle layer is suppressed. Therefore, the cutting tool can have a long tool life.

[0029] (iii) In the hard particles of the cutting tool of this embodiment, the concentration of silicon changes periodically along the first direction from the first main surface to the second main surface of the hard particle layer. As a result, even if distortion occurs in the hard particles and cracks occur on the surface of the coating due to cutting, the progression of the cracks to the base material is effectively suppressed. In addition, the hardness of the hard particles and the hard particle layer is increased, improving the wear resistance of the cutting tool. Therefore, the cutting tool can have a long tool life.

[0030] <Cutting tools> As shown in FIG. 1, the cutting tool 1 of this embodiment includes a substrate 10 and a coating 15 disposed on the substrate 10. FIG. 1 shows a case where the coating 15 is composed only of a hard particle layer 11. The coating 15 preferably covers at least a part of the substrate that is involved in cutting, and more preferably covers the entire substrate. The part of the substrate that is involved in cutting means a region on the substrate surface that is within 500 μm from the cutting edge. Even if a part of the substrate is not covered with this coating or the coating has a partially different configuration, this does not deviate from the scope of the present disclosure.

[0031] <Types of cutting tools> The cutting tool of the present disclosure may be, for example, a drill, an end mill (e.g., a ball end mill), an indexable cutting insert for a drill, an indexable cutting insert for an end mill, an indexable cutting insert for milling, an indexable cutting insert for turning, a metal saw, a gear cutting tool, a reamer, a tap, and the like.

[0032] <Base material> The substrate 10 includes a rake face and a flank face, and any of the substrates known in the art can be used. For example, the substrate is preferably any of cemented carbide (e.g., WC-based cemented carbide containing tungsten carbide and cobalt, which can contain carbonitrides of Ti, Ta, Nb, etc.), cermet (mainly composed of TiC, TiN, TiCN, etc.), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride sintered body, and diamond sintered body.

[0033] The substrate may be made of a cemented carbide containing tungsten carbide and cobalt, and the content of cobalt in the cemented carbide may be 5% by mass or more and 11% by mass or less. This provides an excellent balance between hardness and strength at high temperatures, and has excellent characteristics as a substrate for cutting tools for the above-mentioned applications. When a WC-based cemented carbide is used as the substrate, the substrate may contain free carbon and abnormal layers called η phase or ε phase in its structure.

[0034] Furthermore, the substrate may have a modified surface. For example, in the case of a cemented carbide, a de-β layer may be formed on the surface, and in the case of a cermet, a surface-hardened layer may be formed. The substrate can exhibit the desired effect even if the surface is modified.

[0035] When the cutting tool is an indexable cutting insert, the substrate may or may not have a chip breaker. The shape of the cutting edge ridge can be any of a sharp edge (ridge where the rake face and the flank intersect), a honing (sharp edge with an arc), a negative land (chamfered), or a combination of a honing and a negative land.

[0036] <Coating> <Coating composition> The coating of the present embodiment includes a hard particle layer. The coating of the present embodiment may include other layers as long as it includes a hard particle layer.

[0037] For example, as shown in the cutting tool 1 of FIG. 2, the coating 15 can include, in addition to the hard particle layer 11, an underlayer 12 disposed between the substrate 10 and the hard particle layer 11.

[0038] As shown in the cutting tool 1 of FIG. 3, the coating 15 may include, in addition to the hard particle layer 11 and the underlayer 12 , a surface layer 13 disposed on the hard particle layer 11 .

[0039] As shown in the cutting tool 1 of FIG. 4 , the coating 15 may include, in addition to the hard particle layer 11, the underlayer 12, and the surface layer 13, an intermediate layer 14 disposed between the underlayer 12 and the hard particle layer 11.

[0040] The hard particle layer, underlayer, intermediate layer and surface layer will be described in detail later.

[0041] <Coating thickness> The thickness of the coating in this embodiment may be 2 μm or more and 30 μm or less. Here, the thickness of the coating means the thickness of the entire coating. When the thickness of the entire coating is 3 μm or more, it can have excellent wear resistance. On the other hand, when the thickness of the entire coating is 30 μm or less, it can suppress the occurrence of peeling or destruction of the coating when a large stress is applied between the coating and the substrate during cutting. The lower limit of the thickness of the entire coating may be 2 μm or more, 5 μm or more, 8 μm or more, or 10 μm or more from the viewpoint of improving wear resistance. The upper limit of the thickness of the entire coating may be 30 μm or less, 25 μm or less, or 20 μm or less from the viewpoint of suppressing the occurrence of peeling or destruction of the coating. The thickness of the entire coating may be 5 μm or more and 25 μm or less, or 8 μm or more and 20 μm or less.

[0042] In the present disclosure, the thickness of the coating is measured by the following procedure. A cutting tool is cut out in a cross section parallel to the normal direction of the surface to obtain a measurement sample with an exposed cross section of the coating. The measurement sample is observed with a scanning transmission electron microscope (STEM) to measure the thickness of the coating. The measurement sample is a thin sample processed using an ion slicer or the like. An example of a scanning transmission electron microscope is JEM-2100F (trademark) manufactured by JEOL Ltd. The measurement conditions are an acceleration voltage of 200 kV and a current of 0.3 nA.

[0043] In the present disclosure, the term "thickness" refers to the average thickness. Specifically, the observation magnification of the measurement sample is set to 10,000 times, and a rectangular measurement field of view is set in the electron microscope image with a length of 100 μm parallel to the surface of the cutting tool and a length including the entire thickness of the coating. The thickness width is measured at 10 points in the field of view, and the average value is taken as the "thickness". The thickness (average thickness) of each layer described below is also measured and calculated in the same manner.

[0044] As long as measurements are taken of the same sample, there is almost no variation in the measurement results even if the measurement field of view is changed and measurements are taken multiple times, and it has been confirmed that setting the measurement field of view arbitrarily is not arbitrary.

[0045] <Hard particle layer> <Composition of hard particle layer> The hard particle layer of the present embodiment is composed of a plurality of hard particles composed of titanium, silicon, carbon, and nitrogen. The hard particle layer can also be expressed as a TiSiCN layer composed of hard particles composed of TiSiCN. The TiSiCN layer has high hardness. Therefore, a cutting tool having a TiSiCN layer is excellent in wear resistance. As long as the effects of the present disclosure are not impaired, the hard particle layer can contain impurity elements together with titanium, silicon, carbon, and nitrogen. Examples of the impurity elements include chlorine, cobalt, tungsten, and oxygen. The content of the impurity elements in the hard particle layer can be, for example, 0.5 atomic% or less. The content of the impurity elements in the hard particle layer is measured by TEM (Transmission Electron Microscop e) accompanied by EDX (Energy Dispersive X-ray Spectroscopy) (TEM-EDX).

[0046] As shown in FIG. 5, the hard particle layer 11 includes a first region A1 and a second region A2. The first region A1 is a region sandwiched between the first main surface Q1 on the base material 10 side of the hard particle layer 11 and a virtual surface S1 whose distance from the first main surface Q1 to the hard particle layer 11 side is 0.5 μm. The second region A2 is a region sandwiched between the second main surface Q2 on the side opposite to the first main surface Q1 of the hard particle layer 11 and a virtual surface S2 whose distance from the second main surface Q2 to the hard particle layer side is 0.5 μm.

[0047] The composition of the first region is Ti (1-Xb) Si Xb CN, and the composition of the second region is Ti (1-Xs) Si Xs CN. Here, Xs and Xb satisfy the relationships of Xb - Xs ≧ 0.01 and 0 < Xs < Xb ≦ 0.10.

[0048] The lower limit of Xb-Xs is 0.01 or more, and may be 0.02 or more, 0.03 or more, or 0.04 or more. The upper limit of Xb-Xs may be 0.09 or less, 0.08 or less, or 0.07 or less. Xb-Xs may be 0.01 or more and 0.09 or less, 0.02 or more and 0.08 or less, 0.03 or more and 0.07 or less, or 0.04 or more and 0.07 or less.

[0049] The lower limit of Xs may be 0.01 or more, 0.02 or more, or 0.03 or more. The upper limit of Xs may be 0.09 or less, 0.08 or less, or 0.07 or less. Xs may be 0.01 or more and 0.09 or less, 0.02 or more and 0.08 or less, or 0.03 or more and 0.07 or less.

[0050] The lower limit of Xb may be 0.02 or more, 0.03 or more, or 0.04 or more. The upper limit of Xb may be 0.10 or less, 0.09 or less, or 0.08 or less. Xb may be 0.02 or more and 0.10 or less, 0.03 or more and 0.09 or less, or 0.04 or more and 0.08 or less.

[0051] In the present disclosure, the composition of the first region is Ti (1-Xb) S Xb CN and the composition of the second region Ti (1-Xs) S Xs CN is measured by the following procedure.

[0052] (A1) The cutting tool is cut out with a diamond wire along the normal line of the cutting tool surface to expose the cross section of the hard particle layer. The exposed cross section is subjected to focused ion beam processing (hereinafter also referred to as "FIB processing") to make the cross section mirror-finished.

[0053] (A2) In the cross section processed by FIB, a line analysis is performed along the thickness direction of the coating by EDX (SEM-EDX) attached to an SEM (Scanning Electron Microscopy) to measure the composition. The beam diameter of the line analysis is 0.9 nm or less, the scan interval is 50 nm, and the acceleration voltage is 15 kV. As a result of the line analysis, a region A composed of titanium, silicon, carbon, and nitrogen is identified, except for impurity elements chlorine, tungsten, cobalt, and oxygen. In the above cross section, the region A is identified at three points that do not overlap each other and are spaced apart from each other by 1 μm or more. In the above cross section, the line connecting the positions of the three regions A closest to the substrate corresponds to the first main surface Q1 on the substrate side of the hard particle layer. In the above cross section, the line connecting the positions of the three regions A farthest from the substrate corresponds to the second main surface Q2 opposite to the first main surface Q1 of the hard particle layer. In the above cross section, the region sandwiched between the first principal surface Q1 and the second principal surface Q2 corresponds to the hard particle layer 11.

[0054] (A3) Identifying a first region and a second region in the hard particle layer in the cross section processed by FIB. The first region A1 is a region sandwiched between a first main surface Q1 of the hard particle layer 11 on the substrate 10 side and a virtual surface S1 that is 0.5 μm away from the first main surface Q1 to the hard particle layer 11 side. The second region A2 is a region sandwiched between a second main surface Q2 of the hard particle layer 11 on the opposite side to the first main surface Q1 and a virtual surface S2 that is 0.5 μm away from the second main surface Q2 to the hard particle 11 layer side.

[0055] (A4) In the first region A1, rectangular analysis is performed by SEM-EDX to identify the composition of the first region A1. The rectangular analysis is performed on three non-overlapping rectangular measurement regions of 0.5 μm × 2 μm set in the first region A1. In the present disclosure, the average of the compositions of the three measurement regions is determined to be the composition Ti of the first region A1. (1-Xb) S Xb This corresponds to CN. By the above procedure, Xb can be obtained.

[0056] In the second region A2, rectangular analysis is performed by SEM-EDX to identify the composition of the second region A2. The rectangular analysis is carried out on three non-overlapping rectangular measurement regions of 0.5 μm × 2 μm set within the second region A2. In the present disclosure, the average of the compositions of the three measurement regions corresponds to the composition Ti (1-Xs) Si Xs CN. By the above procedure, Xs can be obtained.

[0057] As long as the measurement is performed on the same sample, it has been confirmed that there is almost no variation in the measurement results even if the cutting position of the cutting tool or the measurement region is changed and the measurement is performed multiple times.

[0058] The hard particle layer of the present embodiment may include a third region sandwiched between the first region and the second region. As long as the effects of the present disclosure are not impaired, the composition of the third region is not particularly limited. The composition of the third region can be a composition that can maintain the continuity of the structure of the hard particle layer. The third region composition Ti (1-Xm) Si Xm CN, if Xs × 0.9 < Xm < Xb × 1.1, it has been confirmed that the effects of the present disclosure are not impaired. The composition of the third region is measured by the same method as the measurement method of the composition of the first region described above.

[0059] ≪Crystal Structure of Hard Particles≫ In the present embodiment, the hard particles have a cubic crystal structure. When the hard particles have a cubic crystal structure, excellent wear resistance and high toughness can be achieved simultaneously. The fact that the hard particles have a cubic crystal structure can be confirmed by pattern analysis of electron beam diffraction with a limited view.

[0060] ≪Change in Silicon Concentration in Hard Particles≫ In the hard particles of the present embodiment, the concentration of silicon changes periodically along the first direction from the first main surface to the second main surface of the hard particle layer. In the hard particles, the fact that the concentration of silicon changes periodically along the first direction from the first main surface to the second main surface of the hard particle layer is confirmed by the following procedure.

[0061] (B1) The cutting tool is cut out with a diamond wire along the normal line of the cutting tool surface to expose the cross section of the hard particle layer. The exposed cross section is subjected to focused ion beam processing (hereinafter also referred to as "FIB processing") to make the cross section mirror-finished.

[0062] (B2) The FIB-machined cross section is observed using a bright-field scanning electron microscope (BF-SEM) to identify a single hard particle. Next, a BE-STEM image of the identified single hard particle is obtained.

[0063] (B3) In the above BF-STEM image, the measurement area (size: 100 nm × 100 nm) is set so as to include an area where 10 or more layers of each of the white layers and the black layers are stacked. The black layers are areas with a high silicon content, and the white layers are areas with a low silicon content.

[0064] (B4) In the measurement area in the BF-STEM image, the stacking direction of the layer shown in white (hereinafter also referred to as the "white layer") and the layer shown in black (hereinafter also referred to as the "black layer") is identified. Specifically, the electron beam diffraction pattern of the selected visual field area is superimposed on the stacking orientation of the white layer and the black layer, and the stacking orientation is identified from the orientation indicated by the diffraction spot.

[0065] (B5) In the measurement area in the BF-STEM image, line analysis is performed along the stacking direction using STEM-attached EDX (Energy Dispersive X-ray Spectroscopy) to measure the composition. The beam diameter of the line analysis is 0.5 nm or less, the scan interval is 0.5 nm, and the length of the line analysis is 50 nm.

[0066] (B6) The results of the line analysis are shown with the X-axis representing the distance from the measurement start point and the Y-axis representing the number of titanium atoms A. Ti and the number of silicon atoms, A Si The number of silicon atoms, A, relative to the total Si Percentage of {A Si / (A Ti +A SiA graph is created in a coordinate system where {A )}×100 in the measurement area. Si / (A Ti +A Si )}×100 (hereinafter, also referred to as "average") is calculated. As the distance from the measurement start point increases, the average value of {A Si / (A Ti +A Si When regions in which the silicon concentration is large and regions in which the silicon concentration is small alternately exist, it is confirmed that the silicon concentration in the hard particles changes periodically along a first direction from the first main surface to the second main surface of the hard particle layer.

[0067] As long as measurements are performed on the same sample, it has been confirmed that there is almost no variation in the measurement results even if the hard particles specified in (B2) above are changed and measurements are performed multiple times.

[0068] <Periodic width of silicon concentration in hard particles> In the hard particles of this embodiment, the periodic width of the silicon concentration along the first direction from the first main surface to the second main surface of the hard particle layer may be 3 nm or more and 20 nm or less. This maintains the strain in the hard particles, further suppresses the growth of cracks in the coating, and further improves the chipping resistance of the cutting tool. The periodic width of the silicon concentration may be 3 nm or more and 15 nm or less, or 5 nm or more and 10 nm or less.

[0069] In the present disclosure, the method for measuring the periodic width of silicon concentration is as follows. A measurement area is set in the same manner as in (B1) to (B3) above. A Fourier transform is performed on the measurement area to obtain a Fourier transform image. In the Fourier transform image, the periodicity in the measurement area appears as spots. The periodic width is calculated by calculating the reciprocal of the distance between the spots and the center of the image showing the maximum intensity in the Fourier transform image.

[0070] As long as measurements are performed on the same sample, it has been confirmed that there is almost no variation in the measurement results even if the measurement is performed multiple times while changing the measurement location.

[0071] <Structure of hard particle layer> The hard particle layer of the present embodiment may have a columnar structure. This makes the hard particle layer resistant to stress in the shear direction and improves wear resistance. Furthermore, the hard particle layer has fewer grain boundaries in the direction perpendicular to the film thickness, which reduces the number of fracture origins and improves chipping resistance.

[0072] In the present disclosure, the hard particle layer having a columnar structure means that the percentage (N1 / N)×100 of the number N1 of first hard particles having an aspect ratio of 3 or more to the number N of all hard particles constituting the hard particle layer is 50% or more. Specifically, whether the hard particle layer has a columnar structure can be confirmed by the following procedure.

[0073] (C1) The cutting tool is cut out with a diamond wire along the normal line of the cutting tool surface to expose the cross section of the hard particle layer. The exposed cross section is subjected to focused ion beam processing (hereinafter also referred to as "FIB processing") to make the cross section mirror-finished.

[0074] (C2) EBSD analysis is performed on the FIB-processed cross section under the following measurement conditions using a field emission scanning electron microscope (FE-SEM) (product name: "SUPRA35VP", manufactured by Carl Zeiss) equipped with an electron backscatter diffraction device (EBSD device). The regions where EBSD analysis is performed (hereinafter also referred to as analysis regions) are three mutually non-overlapping rectangular regions provided in the hard particle layer. The size of the analysis region is a rectangle with a length of 20 μm or more in a direction parallel to the substrate. The length of the analysis region in the thickness direction of the coating can be appropriately set depending on the thickness of the hard particle layer. The length of the analysis region in the thickness direction of the coating is set to be, for example, 90% or more of the thickness of the hard particle layer. (Measurement conditions) Accelerating voltage: 15kV Current value: 1.8nA Irradiation current: 60μm (with HC) Exp:Long 0.03s Binning: 8×8 WD: 15mm Tilt: 70° Step size: 0.02μm BKD :Background Subtraction, Dynamic Background Subtraction, Normalize Intensity histogram Magnification: 20,000x Grain boundary definition: 15° or more

[0075] (C3) For data collected by EBSD analysis, a cleanup process is performed by recognizing only data that satisfy CI>0.1 using the CI Dilation method (single Interation) and Grain CI Standardization. The CI value is calculated using the Voting method. Specifically, it is calculated as CI=(V1-V2) / Videal (V1, 2:1, second solution, Videal: ideal solution).

[0076] (C4) The above EBSD analysis results were analyzed using commercially available software (product name: "OIM7.1", manufactured by TSL Solutions Co., Ltd.) to obtain an IPF map (Inverse Pole Graph) of the above analysis area. F ig u In creating the IPF map, a grain boundary is defined as a boundary where the misorientation angle between adjacent measurement points is 15° or more. The IPF map shows the shape of each grain and the orientation of each grain, with each grain being color-coded.

[0077] (C5) The above software ("O IM7.1") is used to measure the aspect ratio of each of all hard particles in the IPF map of each analysis region. The aspect ratio of a hard particle is the ratio b / a of the long axis a to the short axis b of the hard particle. In the present disclosure, the long axis a is the maximum diameter across the hard particle observed in the cross section, and the short axis b is the maximum diameter of the hard particle along a direction perpendicular to the long axis a. In the present disclosure, the hard particles in the IPF map of the analysis region include both hard particles all of which exist in the IPF map of the analysis region, and hard particles at least a part of which exist in the IPF map of the analysis region.

[0078] (C6) Calculate the percentage (n1 / n)×100 of the number n1 of first hard particles having an aspect ratio of 3 or more to the number n of all hard particles in the IPF map of each analysis region. In the present disclosure, the average of the percentages (n1 / n)×100 in the IPF maps of the three analysis regions corresponds to the percentage (N1 / N)×100 of the number N1 of first hard particles having an aspect ratio of 3 or more to the number N of all hard particles constituting the hard particle layer. When the percentage (N1 / N)×100 is 50% or more, it is confirmed that the hard particle layer has a columnar structure.

[0079] As long as measurements are performed on the same sample, it has been confirmed that there is almost no variation in the measurement results even if the cutting position of the cutting tool or the measurement area is changed and measurements are performed multiple times.

[0080] In the hard particle layer of this embodiment, the lower limit of the percentage (N1 / N)×100 may be 60% or more, 70% or more, 80% or more, or 90% or more. The upper limit of the percentage (N1 / N)×100 may be, for example, 100% or less. The percentage (N1 / N)×100 may be 60% or more and 100% or less, 70% or more and 100% or less, 80% or more and 100% or less, or 90% or more and 100% or less.

[0081] In this embodiment, the ratio L / T of the length L of the hard particles along the first direction to the thickness T of the hard particle layer may be 0.3 or more. This makes the hard particle layer resistant to stress in the shear direction, improving wear resistance. Furthermore, the hard particle layer has fewer grain boundaries in the direction perpendicular to the film thickness, reducing the number of fracture starting points and improving chipping resistance.

[0082] In this embodiment, the lower limit of the ratio L / T may be 0.4 or more, 0.5 or more, or 0.6 or more, from the viewpoint of improving the wear resistance and the chipping resistance. The upper limit of the ratio L / T may be 1.0 or less, or 0.9 or less. T is , it may be 0.3 or more and 1.0 or less, 0.4 or more and 1.0 or less, 0.5 or more and 0.9 or less, or 0.6 or more and 0.9 or less.

[0083] In the present disclosure, the thickness T of the hard particle layer and the length L of the hard particles along the first direction are measured by the following procedure. (D1) Create an IPF map of the analysis area using the same procedures as (C1) to (C4) in the method for confirming that the hard particle layer has a columnar structure. In this procedure, the analysis area in (C1) is a rectangular area with three non-overlapping locations, each with a length of 100 μm parallel to the cutting tool surface and a length including the entire thickness of the coating.

[0084] (D2) Software ("O IM 7.1"), the thickness width is measured at 10 points along a first direction from the first main surface to the second main surface of the hard particle layer in the IPF map of each analysis region, and the average value t is calculated. Here, the first direction is perpendicular to the first main surface of the hard particle layer. In the present disclosure, the average of the average values ​​t of the three analysis regions corresponds to the thickness T of the hard particle layer.

[0085] (D3) Software ("O IM7.1"), the length along the first direction is measured for each of all hard particles in the IPF map of each analysis region, and the average value L1 is calculated. In this disclosure, the hard particles in the IPF map of the analysis region are defined as hard particles that are all present in the IPF map of the analysis region, and hard particles that are at least partially present in the IPF map of the analysis region. IPF Map In the present disclosure, the average of the average values ​​L1 of the three analyzed regions corresponds to the length L of the hard particle along the first direction.

[0086] As long as measurements are performed on the same sample, it has been confirmed that there is almost no variation in the measurement results even if the cutting position of the cutting tool or the measurement area is changed and measurements are performed multiple times.

[0087] <Thickness of hard particle layer> The thickness of the hard particle layer in this embodiment may be 2 μm or more and 15 μm or less. When the thickness of the hard particle layer is 2 μm or more, it can have excellent wear resistance. On the other hand, when the thickness of the hard particle layer is 15 μm or less, it can suppress the occurrence of peeling or destruction of the coating when a large stress is applied between the coating and the substrate during cutting. The lower limit of the thickness of the hard particle layer may be 4 μm or more, 6 μm or more, or 8 μm or more from the viewpoint of improving wear resistance. The upper limit of the thickness of the hard particle layer may be 15 μm or less, or 10 μm or less from the viewpoint of suppressing the occurrence of peeling or destruction of the coating. The thickness of the hard particle layer may be 4 μm or more and 15 μm or less, or 6 μm or more and 10 μm or less.

[0088] <Underlayer> The coating of the first embodiment may include an underlayer provided between the substrate and the hard particle layer. The underlayer may include at least one selected from the group consisting of a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, and an Al2O3 layer.

[0089] By disposing a TiN layer, a TiC layer, a TiCN layer, or a TiBN layer directly on the substrate as the underlayer, the adhesion between the substrate and the coating can be improved. By using an Al2O3 layer as the underlayer, the oxidation resistance of the coating can be improved. The underlayer may have an average thickness of 0.1 μm or more and 20 μm or less. This allows the coating to have excellent wear resistance and chipping resistance.

[0090] <Surface layer> The coating of the first embodiment may include a surface layer provided on the outermost surface of the coating. The surface layer may be a TiN layer or an Al2O3 layer. The TiN layer has a clear color (golden color), so when used as the surface layer, it has an advantage that it is easy to identify the corners of the cutting tip after cutting (identify the used part). By using an Al2O3 layer as the surface layer, the oxidation resistance of the coating can be improved.

[0091] The surface layer may have an average thickness of 0.5 μm or more and 10 μm or less, which improves adhesion between the surface layer and an adjacent layer.

[0092] <Middle Class> The coating of the first embodiment may include an intermediate layer disposed between the underlayer and the hard particle layer. When the underlayer is a TiN layer, the intermediate layer is preferably a TiCN layer. The TiCN layer has excellent wear resistance, so that the coating can have more suitable wear resistance. The average thickness of the intermediate layer may be 1 μm or more and 20 μm or less.

[0093] [Embodiment 2: Manufacturing method of cutting tool] A description will be given of an example of a manufacturing method for the cutting tool according to embodiment 1. The manufacturing method for the cutting tool according to embodiment 1 can include a first step of preparing a substrate, and a second step of forming a coating on the substrate to obtain the cutting tool.

[0094] <1st process> In the first step, a substrate is prepared. Details of the substrate are described in the first embodiment, and therefore the description will not be repeated.

[0095] <Second process> Next, in the second step, a coating is formed on the substrate to obtain a cutting tool. The coating is formed, for example, by using a CVD apparatus shown in FIG. 6. A plurality of substrate setting jigs 52 holding substrates 10 can be installed in the CVD apparatus 50, which are covered by a reaction vessel 53 made of heat-resistant alloy steel. A temperature control device 54 is disposed around the reaction vessel 53, and the temperature control device 54 can control the temperature inside the reaction vessel 53.

[0096] A nozzle 56 having three inlets 55, 57 (the other inlet is not shown) is disposed in the CVD apparatus 50. The nozzle 56 is disposed so as to penetrate the area in which the substrate setting jig 52 is disposed. A plurality of injection holes (a first injection hole 61, a second injection hole 62, and a third injection hole (not shown)) are formed in a portion of the nozzle 56 near the substrate setting jig 52.

[0097] 6, the gases introduced into nozzle 56 from inlets 55, 57, and another inlet (not shown) are not mixed in nozzle 56 either, and are introduced into reaction vessel 53 via different injection holes. Nozzle 56 can rotate about its axis. An exhaust pipe 59 is provided in CVD apparatus 50, and exhaust gas can be discharged to the outside from exhaust port 60 of exhaust pipe 59. Fixtures and the like in reaction vessel 53 are usually made of graphite.

[0098] When the coating includes at least one of an undercoat layer, an intermediate layer, and a surface layer, these layers can be formed by a conventionally known method.

[0099] As raw material gases, TiCl4, SiCl4, and CH3CN are used. TiCl4 is ejected from a plurality of first ejection holes provided in the nozzle, SiCl4 is ejected from a plurality of second ejection holes provided in the nozzle, and CH3CN is ejected from a plurality of third ejection holes provided in the nozzle. Specifically, TiCl4 is introduced into the nozzle 56 from the inlet 55 of the nozzle and ejected from the plurality of first ejection holes 61. SiCl4 is introduced into the nozzle 56 from the inlet 57 of the nozzle and ejected from the plurality of second ejection holes 62. CH3CN is introduced into the nozzle 56 from an inlet (not shown) of the nozzle and ejected from a plurality of third ejection holes (not shown). As the carrier gas, H2 gas, N2 gas, Ar gas, etc. can be used. In the present disclosure, the gas containing the raw material gas and the carrier gas is referred to as the reaction gas.

[0100] When forming the hard particle layer, the following conditions (i) and (ii) are adopted. (i) The percentage (V1 / V)×100 of the volume flow rate V1 of CH3CN with respect to the total volume flow rate V of the entire reaction gas is changed. For example, during the period from the start to the end of the formation of the hard particle layer, the percentage (V1 / V)×100 is gradually decreased.

[0101] (ii) The percentage (V Ti+Si / V Si )×100 of the flow rate V Si of SiCl4 with respect to the total flow rate V Ti+Si of TiCl4 and SiCl4 is changed. For example, during the period from the start to the end of the formation of the hard particle layer, the percentage (V Si / V Ti+Si )×100 is decreased.

[0102] By adopting the above conditions (i) and (ii), the composition of the first region and the second region of the hard particle layer can be changed. In the composition Ti (1-Xb) Si Xb CN of the first region and the composition Ti (1-Xs) Si Xs CN of the second region, it can be adjusted so that Xs and Xb satisfy the relationship of Xb - Xs ≧ 0.01 and 0 < Xs < Xb ≦ 0.10.

[0103] When forming the hard particle layer, reducing the substrate temperature is also effective for adjusting the composition Ti in the first region (1-Xb) Si Xb CN and the composition Ti in the second region (1-Xs) Si Xs CN so that Xs and Xb satisfy the relationship Xb - Xs ≧ 0.01 and 0 < Xs < Xb ≦ 0.10. In particular, for the composition Ti in the first region (1-Xb) Si Xb CN and the composition Ti in the second region (1-Xs) Si Xs CN, to make Xs 0.07 or more and Xb 0.09 or more, it is effective to reduce the substrate temperature when forming the hard particle layer.

[0104] When forming the hard particle layer, film formation is performed while rotating the nozzle. As a result, in the hard particles, the concentration of silicon changes periodically along the growth direction of the hard particle layer.

[0105] In this step, the substrate temperature in the reaction vessel is 800°C to 900°C, and the pressure in the reaction vessel is 50 hPa to 300 hPa. The thickness of the hard particle layer can be controlled by adjusting the flow rate of the raw material gas and the film formation time. The periodic width of the silicon concentration in the hard particles can be controlled by adjusting the rotation speed of the nozzle and the film formation time.

[0106] During the formation of the hard particle layer, the total gas flow rate of the reaction gas can be, for example, 70 L / min to 90 L / min. Here, the "total gas flow rate" indicates the total volume flow rate introduced into the CVD furnace per unit time, assuming the gas at standard conditions (0°C, 1 atm) is an ideal gas.

[0107] (Other steps) Next, the substrate 10 with the film formed is cooled. The cooling rate does not exceed, for example, 5°C / min, and the cooling rate becomes slower as the temperature of the substrate 10 decreases.

[0108] In addition to the above steps, a heat treatment step such as annealing, and a surface treatment step such as surface grinding and shot blasting may be carried out.

[0109] The cutting tool of the first embodiment can be obtained by the above-described manufacturing method. EXAMPLES

[0110] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0111] <Preparation of the substrate> A substrate made of cemented carbide was prepared as the substrate. The composition of the substrate was Co: 10 mass%, NbC: 0.1 mass%, TaC: 2 mass%, and the remainder was WC. The shape of the substrate was SEET13TAGSN-G (a cutting insert with replaceable cutting edge manufactured by Sumitomo Electric Hardmetal Corporation).

[0112] <Coating formation> A coating was formed on the surface of the substrate by the CVD method. The composition of the coating and the average thickness of each layer for each sample are shown in Tables 1, 2, and 3. A column marked with "-" in the tables indicates that no layer is present.

[0113] [Table 1]

[0114] [Table 2]

[0115] [Table 3]

[0116] The underlayer (TiN layer), intermediate layer (TiCN layer) and surface layer (Al2O3 layer) shown in Table 1 are layers formed by a conventionally known CVD method.

[0117] The hard particle layer of each sample shown in Table 1 is formed using the CVD apparatus shown in Fig. 6. The nozzle of the CVD apparatus is provided with a first injection hole, a second injection hole, and a third injection hole. For each sample, the nozzle rotation speed, substrate temperature, and pressure during the formation of the hard particle layer are as shown in Tables 4, 5, and 6.

[0118] [Table 4]

[0119] [Table 5]

[0120] [Table 6]

[0121] In Samples 1 to 39, the percentage (V1 / V)×100 of the volumetric flow rate V1 of CH3CN relative to the volumetric flow rate V of the entire reaction gas was gradually decreased from the start to the end of the formation of the hard particle layer. The changes in the percentage (V1 / V)×100 are shown in Tables 4, 5, and 6. For example, in Sample 1, the percentage (V1 / V)×100 was gradually decreased from 0.5% to 0.4%.

[0122] In Samples 101 to 109, the percentage (V1 / V)×100 was kept constant during the formation of the hard particle layer. The percentage (V1 / V)×100 is as shown in Tables 4, 5, and 6. For example, in Sample 101, the percentage (V1 / V)×100 was kept at 0.4%.

[0123] For samples 1 to 39, the total flow rate of TiCl4 and SiCl4 V Ti+Si Flow rate of SiCl4 V Si Percentage of (V Si / V Ti+Si ) × 100. Percentage (V Si / VTi+Si )×100 is as shown in Tables 4, 5 and 6. For example, in sample 1, the percentage (V Si / V Ti+Si ) × 100 from 25% to 20%.

[0124] In Samples 101 to 109, during the formation of the hard particle layer, the percentage (V Si / V Ti+Si ) × 100 was kept constant. Si / V Ti+Si )×100 is as shown in Tables 4, 5 and 6. For example, in sample 101, the percentage (V Si / V Ti+Si ) × 100 was maintained at 20%.

[0125] In Sample 17 and Samples 29 to 39, the substrate temperature was decreased during the formation of the hard particle layer. The change in substrate temperature is as shown in Tables 5 and 6. For example, in Sample 17, the substrate temperature was decreased from 870° C. to 850° C. In the other samples, the substrate temperature was kept constant during the formation of the hard particle layer.

[0126] Thereafter, the substrate was cooled to obtain a cutting tool for each sample.

[0127] <Structure of hard particle layer> When the hard particle layer of each sample cutting tool was observed with a bright-field scanning electron microscope (BF-SEM), it was confirmed that the hard particle layer was composed of a plurality of hard particles.

[0128] <Composition of hard particle layer> For each sample cutting tool, the composition of the first region of the hard particle layer was Ti (1-Xb) S Xb CN and the composition of the second region Ti (1-Xs) S Xs CN was measured by SEM-EDX. The specific measurement method is as described in embodiment 1. Based on the results obtained, Xb, Xs and Xb-Xs are shown in Tables 7, 8 and 9.

[0129] <Crystal structure of hard particles> The crystal structure of the hard particles in the hard particle layer of each sample cutting tool was confirmed by pattern analysis of electron beam diffraction using a selected area. The results are shown in Tables 7, 8, and 9. In the tables, "cubic" indicates that the hard particles have a cubic structure. In the tables, "cubic + amorphous" indicates that the hard particles contain a cubic structure and amorphous.

[0130] <Changes in silicon concentration in hard particles> In the hard particles of each sample cutting tool, the change in silicon concentration along the first direction from the first main surface to the second main surface of the hard particle layer was confirmed. It was confirmed that in the hard particles of all samples, the silicon concentration changed periodically along the first direction from the first main surface to the second main surface of the hard particle layer.

[0131] <Periodic width of silicon concentration in hard particles> In the hard particles of each sample cutting tool, the periodic width of the silicon concentration along the first direction from the first main surface to the second main surface of the hard particle layer was measured. The specific measurement method is as described in embodiment 1. The results are shown in "Si concentration periodic width" in Tables 7, 8, and 9.

[0132] <Structure of hard particle layer> In the hard particle layer of each sample cutting tool, the percentage (N1 / N)×100 of the number N1 of first hard particles having an aspect ratio of 3 or more to the number N of all hard particles constituting the hard particle layer was measured. The specific measurement method is as described in embodiment 1. The results are shown in Tables 7, 8, and 9.

[0133] When the percentage (N1 / N)×100 of each sample is 50% or more, the hard particle layer is determined to have a columnar structure.

[0134] <l t> For each sample cutting tool, the ratio L / T of the length L of the hard particles along the first direction to the thickness T of the hard particle layer was measured. The specific measurement method is as described in embodiment 1. The results are shown in Tables 7, 8, and 9.

[0135] [Table 7]

[0136] [Table 8]

[0137] [Table 9]

[0138] <Cutting test 1> Cutting was performed under the following cutting conditions using cutting tools of Samples 1 to 15 and Samples 101 to 103, and the cutting length until the flank wear amount reached 0.2 mm was measured. The longer the cutting length, the longer the tool life. The results are shown in Table 10.

[0139] <Cutting conditions> Work material: SKD11 Machining surface size: 100mm x 80mm Cutter: WGC4160R (Sumitomo Electric Hardmetal) Insert: SEET13TAGSN-G Cutting speed Vc:100m / min Feed per tooth fz: 0.2mm / t Cutting depth ap: 1.0mm Cutting fluid: Yes (WET)

[0140] [Table 10]

[0141] <Evaluation> The cutting tools of Samples 1 to 15 correspond to Examples. The cutting tools of Samples 101 to 103 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 1 to 15 have a longer tool life than the cutting tools of Samples 101 to 103 when used in milling of die steel.

[0142] <Cutting test 2> Cutting was performed under the following cutting conditions using cutting tools of Samples 16 to 27 and Samples 104 to 106, and the cutting length until the flank wear amount reached 0.2 mm was measured. The longer the cutting length, the longer the tool life. The results are shown in Table 11.

[0143] <Cutting conditions> Work material: SKD11 Machining surface size: 100mm x 80mm Cutter: WGC4160R (Sumitomo Electric Hardmetal) Insert: SEET13TAGSN-G Cutting speed Vc:130m / min Feed per tooth fz: 0.2mm / t Cutting depth ap: 1.0mm Cutting fluid: Yes (WET)

[0144] [Table 11]

[0145] <Evaluation> The cutting tools of Samples 16 to 27 correspond to Examples. The cutting tools of Samples 104 to 106 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 16 to 27 have a longer tool life than the cutting tools of Samples 104 to 106 when used in milling of die steel.

[0146] <Cutting test 3> Cutting was performed under the following cutting conditions using cutting tools of Samples 28 to 39 and Samples 107 to 109, and the cutting length until the flank wear amount reached 0.2 mm was measured. The longer the cutting length, the longer the tool life. The results are shown in Table 12.

[0147] <Cutting conditions> Work material: SKD11 Machining surface size: 100mm x 80mm Cutter: WGC4160R (Sumitomo Electric Hardmetal) Insert: SEET13TAGSN-G Cutting speed Vc:150m / min Feed per tooth fz: 0.2mm / t Cutting depth ap: 1.0mm Cutting fluid: Yes (WET)

[0148] [Table 12]

[0149] <Evaluation> The cutting tools of Samples 28 to 39 correspond to Examples. The cutting tools of Samples 107 to 109 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 28 to 39 have a longer tool life than the cutting tools of Samples 107 to 109 when used in milling of die steel.

[0150] Although the embodiments and examples of the present disclosure have been described above, it is intended from the outset that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the embodiments and examples described above, and is intended to include the meaning equivalent to the claims and all modifications within the scope. [Explanation of symbols]

[0151] 1 cutting tool, 10 substrate, 11 hard particle layer, 12 undercoat layer, 13 surface layer, 14 intermediate layer, 15 coating, 50 CVD apparatus, 52 substrate setting jig, 53 reaction vessel, 54 temperature control device, 55, 57 inlet, 56 nozzle, 59 exhaust pipe, 60 exhaust port, 61 first injection hole, 62 second injection hole, A1 first region, A2 second region, S1, S2 virtual surfaces.< / l>

Claims

1. A cutting tool comprising a base material and a coating disposed on the base material, The coating includes a hard particle layer, The hard particle layer is composed of a plurality of hard particles made of titanium, silicon, carbon, and nitrogen, The hard particle layer includes a first region and a second region, The first region is a region sandwiched between the first main surface on the base material side of the hard particle layer and a virtual surface S1 whose distance from the first main surface to the hard particle layer side is 0.5 μm, The second region is a region sandwiched between the second main surface on the side opposite to the first main surface of the hard particle layer and a virtual surface S2 whose distance from the second main surface to the hard particle layer side is 0.5 μm, The composition of the first region is Ti （１－Ｘｂ） Si Ｘｂ CN, The composition of the second region is Ti （１－Ｘｓ） Si Ｘｓ CN, The Xs and Xb satisfy the relationships of Xb - Xs ≧ 0.01 and 0 < Xs < Xb ≦ 0.10, The hard particles have a cubic crystal structure, In the hard particles, a cutting tool in which the concentration of silicon varies periodically along a first direction from the first main surface to the second main surface.

2. The cutting tool according to claim 1, wherein the hard particle layer has a columnar structure.

3. The cutting tool according to claim 2, wherein a ratio L1 / T1 of the length L1 of the hard particles along the first direction to the thickness T1 of the hard particle layer is 0.3 or more.

4. The cutting tool according to claim 1 or claim 2, wherein a period width of the concentration of silicon along the first direction in the hard particles is 3 nm or more and 20 nm or less.

5. The cutting tool according to claim 1 or claim 2, wherein an average thickness of the hard particle layer is 2 μm or more and 15 μm or less. Claim 6 The coating includes an underlayer provided between the base material and the hard particle layer, The underlayer includes at least one selected from the group consisting of a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, and an Al ２ O ３ layer, and the cutting tool according to claim 1 or claim 2. Claim 7 The coating includes a surface layer provided on the outermost surface of the coating, The surface layer is a TiN layer or an Al ２ O ３ layer, and the cutting tool according to claim 1 or claim 2.

Images