cutting tools

Abstract

A cutting tool comprising a substrate and a coating disposed on the substrate, the coating including a first layer, the first layer comprising a plurality of hard particles, the hard particles comprising titanium, silicon, carbon, and nitrogen, the hard particles having a cubic crystal structure, the first layer having a columnar structure, and a number N of titanium atoms in the first layer. Ti and the number of silicon atoms, N Si The number of silicon atoms N Si Ratio of N Si / (N Ti +N Si ) is 0.01 or more and 0.10 or less, and in the first layer, the number of carbon atoms N C and the number of nitrogen atoms, N N The number of carbon atoms N C Ratio of N C / (N C +N N ) is 0.60 or more and 0.85 or less, the hard particles have a laminated structure in which first unit layers and second unit layers are alternately laminated, the first unit layers and the second unit layers each consist of the titanium, the silicon, the carbon, and the nitrogen, a ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the first unit layer is greater than a ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the second unit layer, and a ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the first unit layer is greater than a ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the second unit layer.

Description

[Technical Field]

[0001] The present disclosure relates to cutting tools. [Background technology]

[0002] Conventionally, cutting tools have been developed in which a TiSiCN film is formed on a substrate in order to improve the wear resistance of cutting tools (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 230363 Summary of the Invention

[0004] A cutting tool according to the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, the coating including a first layer, the first layer being composed of a plurality of hard particles, the hard particles being composed of titanium, silicon, carbon, and nitrogen, the hard particles having a cubic crystal structure, the first layer being a columnar structure, and the number of titanium atoms in the first layer being N Ti and the number of silicon atoms, N Si The number of silicon atoms N Si Ratio of N Si / (N Ti +N Si ) is 0.01 or more and 0.10 or less, and in the first layer, the number of carbon atoms N C and the number of nitrogen atoms, N N The number of carbon atoms N C Ratio of N C / (N C +N N) is 0.60 or more and 0.85 or less, the hard particles have a laminated structure in which first unit layers and second unit layers are alternately laminated, the first unit layers and the second unit layers each consist of the titanium, the silicon, the carbon, and the nitrogen, a ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the first unit layer is greater than a ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the second unit layer, and a ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the first unit layer is greater than a ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the second unit layer. [Brief explanation 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. [Figure 2] FIG. 2 is a schematic view showing another example of a cross section of the cutting tool according to the first embodiment. [Figure 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. [Figure 5] FIG. 5 is a schematic cross-sectional view of an example of a CVD apparatus used in the method for manufacturing a cutting tool according to the second embodiment. [Figure 6] FIG. 6 is an enlarged view of region VII in FIG. [Figure 7] FIG. 7 is a cross-sectional view of the nozzle 56 taken along line XVII-XVII in FIG. [Figure 8] FIG. 8 is a cross-sectional view of the nozzle used in Samples 1-6. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] Cutting tools with a high-hardness TiSiCN film have excellent wear resistance. However, when such cutting tools are used to continuously cut chromium-molybdenum steel (SCM415), the high affinity between silicon and iron can cause welding, potentially shortening the tool's life. For this reason, there is a demand for cutting tools that can maintain a long tool life, especially when used to continuously cut chromium-molybdenum steel.

[0007] Therefore, an object of the present disclosure is to provide a cutting tool that can have a long tool life, particularly when used for continuous machining of chromium-molybdenum 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 when used in continuous machining of chromium-molybdenum steel.

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. (1) A cutting tool according to the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, the coating including a first layer, the first layer being composed of a plurality of hard particles, the hard particles being composed of titanium, silicon, carbon, and nitrogen, the hard particles having a cubic crystal structure, the first layer being a columnar structure, and the number of titanium atoms in the first layer being N Ti and the number of silicon atoms, N Si The number of silicon atoms N Si Ratio of N Si / (N Ti +N Si ) is 0.01 or more and 0.10 or less, and in the first layer, the number of carbon atoms N C and the number of nitrogen atoms, N N The number of carbon atoms N C Ratio of N C / (N C +N N) is 0.60 or more and 0.85 or less, the hard particles have a laminated structure in which first unit layers and second unit layers are alternately laminated, the first unit layers and the second unit layers each consist of the titanium, the silicon, the carbon, and the nitrogen, a ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the first unit layer is greater than a ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the second unit layer, and a ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the first unit layer is greater than a ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the second unit layer.

[0010] According to the present disclosure, it is possible to provide a cutting tool that can have a long tool life, particularly when used in continuous machining of chromium-molybdenum steel.

[0011] (2) In the above (1), the average thickness of the first unit layer may be 2 nm or more and 15 nm or less, and the average thickness of the second unit layer may be 2 nm or more and 15 nm or less, thereby further improving the tool life.

[0012] (3) In the above (1) or (2), the average total thickness of the adjacent first unit layer and second unit layer may be 4 nm or more and 30 nm or less, which further improves the tool life.

[0013] (4) In any one of the above (1) to (3), the thickness of the first layer may be 1.0 μm or more and 15 μm or less, thereby further improving the tool life.

[0014] (5) In any one of the above (1) to (4), the coating includes a second layer disposed between the substrate and the first layer, The second layer 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.

[0015] This further improves the tool life.

[0016] (6) In any of the above (1) to (5), the coating may include a third layer disposed on the surface side of the first coating, and the third layer may include at least one layer 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.

[0017] This makes it easier to identify the used portion of the cutting tool after cutting, and further improves the sliding properties of the coating.

[0018] (7) In any of the above (1) to (6), x1 may be 0.01 or more and 0.11 or less, and y1 may be 0.60 or more and 0.85 or less. This improves the hardness, oxidation resistance, and sliding properties of the first layer in a balanced manner.

[0019] (8) In the above (7), the difference between x1 and x2 may be 0.01 or more and 0.07 or less, and the difference between y1 and y2 may be 0.01 or more and 0.10 or less. This improves the hardness, oxidation resistance, and sliding properties of the first layer in a balanced manner.

[0020] [Details of the embodiments of the present disclosure] 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 numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0021] In the present disclosure, the notation in the form "A to B" means greater than or equal to A and less than or equal to B, and when no unit is specified for A and only a unit is specified for B, the unit of A and the unit of B are the same.

[0022] 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.

[0023] In this disclosure, when one or more numerical values ​​are listed as the lower limit and upper limit of a numerical range, the combination of any one numerical value listed in the lower limit and any one numerical value listed in the upper limit is also disclosed.

[0024] In this disclosure, "comprises," "includes," "has," and variations thereof are open-ended terms. Open-ended terms may or may not include additional elements in addition to the required elements. The term "consisting of" is closed-ended. However, even a configuration expressed in closed terms may include additional elements that are normally incidental impurities or unrelated to the subject technology.

[0025] [Embodiment 1: Cutting tool] A cutting tool according to one embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") will be described with reference to Figures 1 to 4. The cutting tool 1 of the present embodiment is a cutting tool 1 including a substrate 10 and a coating 15 disposed on the substrate 10, the coating 15 including a first layer 11, the first layer 11 being made of a plurality of hard particles, the hard particles being made of titanium, silicon, carbon, and nitrogen, the hard particles having a cubic crystal structure, the first layer 11 having a columnar structure, and the number of titanium atoms N in the first layer 11 being 0. Ti and the number of silicon atoms, N Si The number of silicon atoms, N, Si Ratio of N Si / (N Ti +N Si ) is 0.01 or more and 0.10 or less, and in the first layer 11, the number of carbon atoms N C and the number of nitrogen atoms, N N The number of carbon atoms, N, C Ratio of N C / (N C +N N) is 0.60 or more and 0.85 or less, the hard particles have a layered structure in which first unit layers and second unit layers are alternately stacked, each of the first unit layers and the second unit layers is made of titanium, silicon, carbon and nitrogen, the ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the first unit layer is greater than the ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the second unit layer, and the ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the first unit layer is greater than the ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the second unit layer.

[0026] The cutting tool of this embodiment has a long tool life, especially when used for continuous machining of chromium-molybdenum steel. The reason for this is not clear, but is presumed to be as follows.

[0027] (i) In the cutting tool of this embodiment, the coating includes a first layer made of a plurality of hard particles. The hard particles are made of titanium, silicon, carbon, and nitrogen and have a cubic crystal structure, so that the first layer has high hardness. Therefore, the cutting tool has excellent wear resistance.

[0028] (ii) In the first layer of the cutting tool of this embodiment, the ratio N C / (N C +N N The average carbon content is between 0.60 and 0.85, which improves the sliding properties of the first layer and prevents the workpiece from welding to the cutting tool during cutting.

[0029] (iii) The hard particles of the cutting tool of this embodiment have a layered structure in which first unit layers and second unit layers are alternately stacked. The composition and crystal lattice are discontinuous at the interface between the first unit layers and the second unit layers. Therefore, even if cracks occur during cutting, the propagation of the cracks at the interface can be suppressed.

[0030] (iv) The ratio x1 of the first unit layer of the hard particles of the cutting tool of this embodiment is greater than the ratio x2 of the second unit layer, and the ratio y1 of the first unit layer is greater than the ratio y2 of the second unit layer. The first unit layer has a relatively higher silicon and carbon content than the second unit layer. The first unit layer has a high silicon content, which gives it excellent hardness and oxidation resistance. On the other hand, silicon has a high affinity with iron in the workpiece, and layers containing silicon are generally prone to welding. In this embodiment, the high carbon content of the first unit layer improves the sliding properties of the first unit layer, and the occurrence of welding is suppressed for the entire coating.

[0031] <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 illustrates a case in which the coating 15 is composed only of a first layer 11. The coating 15 may cover at least a portion of the substrate that is involved in cutting, or may cover the entire surface of the substrate. The portion of the substrate that is involved in cutting refers to an area on the substrate surface that is within 500 μm of the cutting edge ridge. As long as the effects of the present disclosure are not impaired, it does not depart from the scope of the present disclosure even if a portion of the substrate is not coated with a coating or the coating configuration is partially different.

[0032] <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, etc.

[0033] <Base material> In this embodiment, the substrate can be a conventionally known material. For example, the substrate can be made of cemented carbide (for example, a 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, or diamond sintered body.

[0034] The substrate is made of a cemented carbide containing tungsten carbide and cobalt, and the cobalt content in the cemented carbide may be 5% by mass or more and 11% by mass or less. This provides an excellent balance of hardness and strength at high temperatures, and has excellent properties as a substrate for cutting tools for the above-mentioned applications. When a WC-based cemented carbide is used as the substrate, its structure may contain free carbon and abnormal phases called η phase or ε phase.

[0035] The surface of the substrate may be modified. 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. Even if the surface of the substrate is modified, the desired effect can be achieved.

[0036] 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 (the ridge where the rake face and the flank intersect), a honed edge (a sharp edge with a radius), a negative land (a chamfered edge), or a combination of a honed edge and a negative land.

[0037] <Coating> <Coating composition> In this embodiment, the coating includes a first layer. The coating of this embodiment may include other layers as long as it includes the first layer.

[0038] As shown in FIG. 2, the coating 15 of the cutting tool 1 may include a second layer 12 disposed between the substrate 10 and the first layer 11 .

[0039] As shown in FIG. 3, the coating 15 of the cutting tool 1 may include a third layer 13 disposed on the surface side of the coating 15 of the first layer 11 .

[0040] The first, second and third layers will be described in detail below.

[0041] <Coating thickness> In this embodiment, the thickness of the coating may be 1 μm or more and 30 μm or less. Here, the thickness of the coating refers to the thickness of the entire coating. When the thickness of the entire coating is 1 μm or more, excellent wear resistance can be obtained. On the other hand, when the thickness of the entire coating is 30 μm or less, peeling or breakage of the coating can be suppressed when a large stress is applied between the coating and the substrate during cutting. The thickness of the entire coating may be 3 μm or more and 25 μm or less, or 5 μm or more and 20 μm or less.

[0042] In the present disclosure, the thickness of a coating is measured by the following procedure: A cutting tool is cut into a cross section parallel to the normal direction of the surface to obtain a measurement sample with the cross section of the coating exposed. 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 section sample processed using an ion slicer or the like. An example of a scanning transmission electron microscope is the 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] The measurement sample was observed at a magnification of 10,000x, and a rectangular measurement field of view was set in the electron microscope image, with a length parallel to the cutting tool surface of 100 μm and a length equal to or greater than the entire thickness of the coating. The thickness of the coating was measured at 10 points within the field of view, and the average value was taken as the "coating thickness." The thickness (average thickness) of each layer described below was also measured and calculated in the same manner.

[0044] As long as measurements are made on the same sample, it has been confirmed that there is almost no variation in the measurement results even if the selected location of the measurement field is changed arbitrarily and measurements are performed multiple times.

[0045] <First layer> <Composition of the first layer> In this embodiment, the first layer is made of a plurality of hard particles, and the hard particles are made of titanium, silicon, carbon, and nitrogen. In the first layer of this embodiment, the number of titanium atoms N Ti and the number of silicon atoms, N Si The number of silicon atoms, N, Si Ratio of N Si / (N Ti +N Si The average of N is between 0.01 and 0.10. Si / (N Ti +N Si When the average of N is 0.01 or more, the hardness and oxidation resistance of the first layer are improved. Si / (N Ti +N Si When the average of ) is 0.10 or less, the first layer can have good welding resistance.

[0046] N Si / (N Ti +N Si ) may be 0.02 or more and 0.09 or less, or 0.02 or more and 0.07 or less, or 0.02 or more and 0.05 or less.

[0047] In the first layer of this embodiment, the number of carbon atoms N C and the number of nitrogen atoms, N N The number of carbon atoms, N, C Ratio of N C / (N C +N N ) is between 0.60 and 0.85. C / (N C +N N When the average of N is 0.60 or more, the sliding properties of the first layer are improved. C / (N C +NN When the average of ) is 0.85 or less, the first layer can have good chipping resistance.

[0048] N C / (N C +N N ) may be 0.65 or greater and 0.85 or less, 0.70 or greater and 0.85 or less, or 0.75 or greater and 0.85 or less.

[0049] In the present disclosure, N in the first layer Si / (N Ti +N Si ) and N C / (N C +N N The average of is measured by the following procedure.

[0050] (A1) The cutting tool is cut with a diamond wire along the normal to the surface of the cutting tool to expose the cross section of the first layer. The exposed cross section is then subjected to focused ion beam processing (hereinafter also referred to as "FIB processing") to make the cross section mirror-finished.

[0051] (A2) A rectangular analysis is performed on the cross section of the first layer using an energy dispersive X-ray spectroscope (EDX) (TEM-EDX) attached to a transmission electron microscope (TEM) to identify the composition of the first layer. The rectangular analysis is performed on three non-overlapping rectangular measurement areas of 0.5 μm × 2 μm set in the cross section of the first layer. In each of the three measurement areas, N Si / (N Ti +N Si ) and N C / (N C +N N ) is calculated from the three measurement areas. Si / (N Ti +N Si ) and N C / (N C +N N) is calculated. The average is calculated based on the N Si / (N Ti +N Si ) and N C / (N C +N N ) corresponds to the average.

[0052] As long as measurements are made on the same sample, it has been confirmed that there is almost no variation in the measurement results even if the selected location of the measurement field is changed arbitrarily and measurements are made multiple times.

[0053] <First Layer Organization> In this embodiment, the first layer has a columnar structure. This makes the first layer resistant to shear stress and improves wear resistance. Furthermore, the first layer has fewer grain boundaries in the direction perpendicular to the film thickness, which reduces fracture origins and improves chipping resistance.

[0054] In the present disclosure, the first 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 first layer is 60% or more. Specifically, the columnar structure of the first layer can be confirmed by the following procedure.

[0055] (B1) The cutting tool is cut with a diamond wire along the normal to the surface of the cutting tool to expose the cross section of the first layer. The exposed cross section is then subjected to FIB processing to create a mirror-finished cross section.

[0056] (B2) The FIB-processed cross section is subjected to EBSD analysis 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 (EBSD) device. The regions where EBSD analysis is performed (hereinafter also referred to as analysis regions) are three non-overlapping rectangular regions provided within the first layer. The size of the analysis regions is a rectangle with a length of 20 μm or more in the direction parallel to the substrate. The length of the analysis regions in the thickness direction of the coating can be set appropriately depending on the thickness of the first layer. The length of the analysis regions in the thickness direction of the coating is set, for example, to be 90% or more of the thickness of the first layer. (Measurement conditions) Accelerating voltage: 15 kV Current value: 1.8nA Irradiation current: 60 μm (with HC) Exp:Long 0.03s Binning: 8×8 WD: 15mm Tilt: 70° Step size: 0.02 μm BKD :Background Subtraction, Dynamic Background Subtraction, Normalize Intensity Histogram Magnification: 20,000x Grain boundary definition: 15° or more

[0057] (B3) For data collected by EBSD analysis, a cleanup process is performed by using the CI Dilation method (single Interaction) and Grain CI Standardization to identify only data that satisfy CI > 0.1. 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).

[0058] (B4) The EBSD analysis results were analyzed using commercially available software (product name: "OIM7.1", manufactured by TSL Solutions Co., Ltd.), and an IPF map (Inverse Pole Graph) of the analysis area was obtained. F An IPF map (inverse pole figure orientation map) is created. In creating the IPF map, a grain boundary is defined as a misorientation angle of 15° or more between adjacent measurement points. The IPF map shows the shape of each grain and the orientation of each grain, using different colors.

[0059] (B5) The above software ("O IM 7.1") 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 diameter a to the short diameter b of the hard particle. In the present disclosure, the long diameter a is the maximum diameter across of the hard particle observed in the cross section, and the short diameter b is the maximum diameter of the hard particle along a direction perpendicular to the long diameter a. In the present disclosure, hard particles in the IPF map of the analysis region include both hard particles whose entirety exists in the IPF map of the analysis region and hard particles whose at least a portion exists in the IPF map of the analysis region.

[0060] (B6) Calculate the percentage (n1 / n) × 100 of the number n1 of first hard particles with an aspect ratio of 3 or more relative 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 three analysis regions corresponds to the percentage (N1 / N) × 100 of the number N1 of first hard particles with an aspect ratio of 3 or more relative to the number N of all hard particles constituting the first layer. If the percentage (N1 / N) × 100 is 60% or more, it is confirmed that the first layer has a columnar structure.

[0061] As long as measurements are made on the same sample, it has been confirmed that there is almost no variation in the measurement results even if measurements are made multiple times by changing the cutting tool cut-out position or measurement area.

[0062] <Hard particles> <Hard particle composition> In this embodiment, the hard particles are composed of titanium, silicon, carbon, and nitrogen. The hard particles may contain inevitable impurity elements in addition to titanium, silicon, carbon, and nitrogen, as long as the effects of the present disclosure are not impaired. The hard particles may be composed of titanium, silicon, carbon, nitrogen, and inevitable impurity elements. Examples of inevitable impurity elements include chlorine, cobalt, tungsten, and oxygen. The content of inevitable impurity elements in the hard particles may be, for example, 0.5 atomic % or less. The content of inevitable impurity elements in the hard particles is measured by TEM-EDX.

[0063] <Crystal structure of hard particles> In this embodiment, the hard particles have a cubic crystal structure. When the hard particles have a cubic crystal structure, the first layer can have both excellent wear resistance and high toughness. The fact that the hard particles have a cubic crystal structure can be confirmed by pattern analysis of selected area electron diffraction.

[0064] <Composition of the first unit layer and the second unit layer> In this embodiment, the hard particles have a layered structure in which first unit layers and second unit layers are alternately stacked. Each of the first unit layers and the second unit layers is composed of titanium, silicon, carbon, and nitrogen. As long as the effects of the present disclosure are not impaired, each of the first unit layers and the second unit layers may contain inevitable impurity elements in addition to titanium, silicon, carbon, and nitrogen. Each of the first unit layers and the second unit layers may be composed of titanium, silicon, carbon, nitrogen, and inevitable impurity elements. Examples of inevitable impurity elements include chlorine, cobalt, tungsten, and oxygen. The content of the inevitable impurity elements in each of the first unit layers and the second unit layers may be, for example, 0.5 atomic % or less. The content of the inevitable impurity elements in each of the first unit layers and the second unit layers is measured by TEM-EDX.

[0065] In this embodiment, the ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the first unit layer is greater than the ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the second unit layer, and the ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the first unit layer is greater than the ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the second unit layer.

[0066] Whether x1 is greater than x2 and y1 is greater than y2 can be confirmed by the following procedure. (C1) The cutting tool is cut with a diamond wire along the normal to the surface of the cutting tool to expose the cross section of the first layer. The exposed cross section is then subjected to FIB processing to create a mirror finish.

[0067] (C2) The FIB-processed cross section is observed using a bright-field scanning electron microscope (BF-SEM) to obtain a BF-STEM image.

[0068] (C3) In the BF-STEM image, 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") are identified. The black layer is a region with a high silicon content and corresponds to the first unit layer. The white layer is a region with a low silicon content and corresponds to the second unit layer.

[0069] (C4) Five first unit layers are arbitrarily selected, and elemental analysis is performed on each first unit layer to identify the composition, and x1 and y1 of each first unit layer are obtained. The composition of each first unit layer is Ti (1-x1) Si x1 C y1 N (1-y1) Five second unit layers are arbitrarily selected, and elemental analysis is performed on each second unit layer to identify the composition, and x2 and y2 of each second unit layer are obtained. The composition of each second unit layer is Ti (1-x2) Si x2 C y2 N (1-y2) The conditions for elemental analysis are as follows: Spot diameter: 7cm Aperture size: 30 μm Current value: 35pA Accelerating voltage: 200 kV

[0070] When the number of each of the first unit layers and the second unit layers is four or less, elemental analysis is performed on all unit layers to determine the composition of each unit layer, thereby obtaining x1, x2, y1, and y2.

[0071] In the present disclosure, if the average of x1 measured in the first unit layer is greater than the average of x2 measured in the second unit layer, it is determined that the ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the first unit layer is greater than the ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the second unit layer.

[0072] In the present disclosure, if the average of the measured y1 of the first unit layer is greater than the average of the measured y2 of the second unit layer, it is determined that the ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the first unit layer is greater than the ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the second unit layer.

[0073] In the above (C3), when the white layers and the black layers are alternately laminated, the hard particles are determined to have a laminated structure in which the first unit layers and the second unit layers are alternately laminated.

[0074] As long as measurements are made on the same sample, it has been confirmed that there is almost no variation in the measurement results even when measurements are made multiple times with different hard particles specified in (C2) above.

[0075] x1 may be 0.01 or more and 0.11 or less, 0.02 or more and 0.08 or less, or 0.02 or more and 0.06 or less, and y1 may be 0.60 or more and 0.85 or less, 0.65 or more and 0.85 or less, or 0.70 or more and 0.85 or less.

[0076] The difference between x1 and x2 (x1-x2) may be 0.01 or more and 0.07 or less, 0.02 or more and 0.06 or less, or 0.02 or more and 0.05 or less, where the difference between x1 and x2 (x1-x2) is the difference between the average of x1 in the first unit layer and the average of x2 in the second unit layer.

[0077] The difference between y1 and y2 (y1-y2) may be 0.01 or more and 0.10 or less, 0.01 or more and 0.08 or less, or 0.02 or more and 0.08 or less. Here, the difference between y1 and y2 (y1-y2) is the difference between the average of y1 in the first unit layer and the average of y2 in the second unit layer.

[0078] The above ranges of x1, x2, y1, y2, x1-x2, and y1-y2 can be arbitrarily combined.

[0079] The first unit layer is Ti (1-x1) Si x1 C y1 N (1-y1) The second unit layer is a Ti (1-x2) Si x2 C y2 N (1-y2) It can be expressed as a sheaf, where x1 and x2 satisfy x1>x2, and y1 and y2 satisfy y1>y2.

[0080] <Average thickness of first unit layer and average thickness of second unit layer> In this embodiment, the average thickness of the first unit layer may be 2 nm or more and 15 nm or less, and the average thickness of the second unit layer may be 2 nm or more and 15 nm or less. This improves the effect of suppressing crack propagation at the interface between the first unit layer and the second unit layer. The average thickness of the first unit layer may be 3 nm or more and 10 nm or less, or 3 nm or more and 8 nm or less. The average thickness of the second unit layer may be 3 nm or more and 10 nm or less, or 3 nm or more and 8 nm or less.

[0081] <<Average total thickness of adjacent first and second unit layers>> The total thickness of adjacent first and second unit layers may be 4 nm to 30 nm, 6 nm to 20 nm, or 6 nm to 12 nm. Adjacent first and second unit layers refer to one first unit layer and one second unit layer adjacent to each other. The total thickness of adjacent first and second unit layers corresponds to the average total thickness of five pairs of adjacent first and second unit layers.

[0082] <First layer thickness> The thickness of the first layer in this embodiment may be 1.0 μm or more and 15 μm or less. When the thickness of the first layer is 1.0 μm or more, excellent wear resistance can be obtained. On the other hand, when the thickness of the first layer is 15 μm or less, peeling or breakage of the coating can be suppressed when a large stress is applied between the coating and the substrate during cutting. The thickness of the first layer may be 4 μm or more and 15 μm or less, or 6 μm or more and 10 μm or less.

[0083] <Second layer> The coating of this embodiment may include a second layer disposed between the substrate and the first layer, and the second layer may include at least one layer 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.

[0084] By placing a TiN layer, TiC layer, TiCN layer, TiBN layer, or TiCNO layer directly on the substrate as the second layer, the adhesion between the substrate and the coating can be improved. By using an Al2O3 layer as the second layer, the oxidation resistance of the coating can be improved. The average thickness of the second layer may be 0.1 μm or more and 20 μm or less. This allows the coating to have excellent wear resistance and chipping resistance.

[0085] <Third layer> The coating of embodiment 1 may include a third layer disposed on the surface side of the first layer. The third layer 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. Because the TiN layer has a clear color (golden), when disposed on the outermost surface of the coating as the third layer, it has the advantage of making it easy to identify the used portion of the cutting tool after cutting. Using a TiC layer, a TiCN layer, a TiBN layer, or a TiCNO layer as the third layer can improve the sliding properties of the coating. Using an Al2O3 layer as the third layer can enhance the oxidation resistance of the coating.

[0086] The average thickness of the third layer may be 0.5 μm or more and 10 μm or less, which improves the adhesion between the third layer and the adjacent layer.

[0087] [Embodiment 2: Method for manufacturing a cutting tool] A description will be given of an example of a method for manufacturing the cutting tool according to embodiment 1. The method for manufacturing 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.

[0088] <First step> In the first step, a substrate is prepared. Details of the substrate are described in the first embodiment, and therefore, the description thereof will not be repeated.

[0089] <Second process> Next, in the second step, a coating is formed on the substrate to obtain a cutting tool. The coating is formed using, for example, a CVD apparatus shown in FIG. 5. A plurality of substrate setting jigs 52 holding substrates 10 can be placed inside the CVD apparatus 50, and these are covered by a reaction vessel 53 made of heat-resistant alloy steel. In addition, a temperature control device 54 is arranged around the reaction vessel 53, and this temperature control device 54 can control the temperature inside the reaction vessel 53.

[0090] A nozzle 56 having three gas flow paths (a first gas flow path 55, a second gas flow path 57, and the other gas flow path not shown) through which source gases pass 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 are formed in the nozzle 56 in the vicinity of the substrate setting jig 52 to inject the gas that has passed through the gas flow paths.

[0091] Fig. 7 is a cross-sectional view of the nozzle 56 taken along line XVII-XVII in Fig. 6. As shown in Fig. 7, the nozzle 56 is provided with a first gas flow passage 55, a second gas flow passage 57, and a third gas flow passage 58. SiCl4 gas and C2H4 gas pass through the first gas flow passage 55, TiCl4 gas passes through the second gas flow passage 57, and CH3CN gas passes through the third gas flow passage 58.

[0092] The first gas flow passage 55 communicates with the first injection holes 55a. The gas that has passed through the first gas flow passage 55 is injected from the first injection holes 55a towards the substrate. The second gas flow passage 57 communicates with the second injection holes 57a. The gas that has passed through the second gas flow passage 57 is injected from the second injection holes 57a towards the substrate. The third gas flow passage 58 communicates with the third injection holes 58a. The gas that has passed through the third gas flow passage 58 is injected from the third injection holes 58a towards the substrate.

[0093] The carrier gas may be H2 gas, N2 gas, Ar gas, or the like. The carrier gas is injected from each of the first injection hole, the second injection hole, and the third injection hole. In this disclosure, a gas containing the raw material gas and the carrier gas is referred to as a reaction gas.

[0094] The nozzle is rotated during the formation of the first layer. This causes gases with high SiCl4 and C2H4 concentrations and gases with high TiCl4 concentrations to alternately adsorb onto the substrate, allowing the hard particles contained in the first layer to have a layered structure in which first and second unit layers are alternately stacked. The ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and silicon atoms in the first unit layer is greater than the ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and silicon atoms in the second unit layer, and the ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and nitrogen atoms in the first unit layer is greater than the ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and nitrogen atoms in the second unit layer.

[0095] In this process, the substrate temperature in the reaction vessel is 800°C to 900°C, and the pressure in the reaction vessel is 50 hPa to 200 hPa. The thickness of the first layer can be controlled by adjusting the flow rate of the source gas and the deposition time. The average thickness of each of the first unit layer and the second unit layer can be controlled by adjusting the rotation speed of the nozzle and the deposition time.

[0096] During the formation of the first layer, the total flow rate of the reactive gas is set to 90 L / min to 150 L / min. Here, the "total gas flow rate" refers to the total volumetric flow rate introduced into the CVD furnace per unit time, assuming that the gas is an ideal gas under standard conditions (0°C, 1 atmosphere).

[0097] When the coating includes at least one of the second layer, intermediate layer, and third layer, these layers can be formed by a conventionally known method.

[0098] (Other processes) The substrate on which the coating is formed is then cooled, for example, at a cooling rate not exceeding 5°C / min, and the cooling rate slows as the temperature of the substrate decreases.

[0099] In addition to the above steps, a heat treatment step such as annealing, and a surface treatment step such as surface grinding or shot blasting may be carried out.

[0100] The cutting tool of the first embodiment can be obtained by the above-described manufacturing method. [Example]

[0101] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0102] <Preparing the substrate> A substrate made of cemented carbide was prepared as the substrate. The composition of the substrate was 6 mass % Co, 1.5 mass % NbC, and the remainder was WC. The shape of the substrate was CNMG120408N-GU.

[0103] <Coating formation> A coating was formed on the surface of the substrate by CVD. The composition of the coating and the thickness of each layer for each sample are shown in Table 1. A "-" in Table 1 indicates that the corresponding layer does not exist. The first layer is composed of multiple hard particles, which consist of titanium, silicon, carbon, and nitrogen. The second and third layers shown in Table 1 are layers formed by conventional CVD methods.

[0104] [Table 1]

[0105] The first layer of each sample was formed using the CVD apparatus shown in Figure 5. For samples marked with "A" in the "Type" column of "Nozzle" in Table 2, the nozzle 56 shown in Figure 7 was used. SiCl4 gas and C2H4 gas passed through the first gas flow path 55 of the nozzle 56, TiCl4 gas passed through the second gas flow path 57, and CH3CN gas passed through the third gas flow path 58.

[0106] For samples with "B" in the "Type" column of "Nozzle" in Table 2, the nozzle 56 shown in Figure 8 was used. SiCl4 gas passed through the first gas flow path 55 of the nozzle 56, TiCl4 gas and C2H4 gas passed through the second gas flow path 57, and CH3CN gas passed through the third gas flow path 58.

[0107] The gas that has passed through the first gas flow passage 55 is injected toward the substrate from the first injection holes 55a. The gas that has passed through the second gas flow passage 57 is injected toward the substrate from the second injection holes 57a. The gas that has passed through the third gas flow passage 58 is injected toward the substrate from the third injection holes 58a.

[0108] For each sample, the percentage (V1 / V) of the volumetric flow rate V1 of SiCl4 relative to the volumetric flow rate V of the entire reaction gas during the formation of the first layer, the percentage (V2 / V) of the volumetric flow rate V2 of C2H4 relative to V, the nozzle rotation speed, the substrate temperature, and the pressure are shown in Table 2.

[0109] [Table 2]

[0110] The substrate was then cooled to obtain a cutting tool for each sample.

[0111] <First layer configuration> When the cross section of the first layer of each sample cutting tool was observed using a bright-field scanning electron microscope (BF-SEM), it was confirmed that the first layer was composed of multiple hard particles. Furthermore, the hard particles of the samples marked "Yes" in the "Layered Structure" column of Table 3 were confirmed to have a layered structure in which first unit layers and second unit layers were alternately stacked. The hard particles of the samples marked "No" in the "Layered Structure" column of Table 3 did not have a layered structure. The hard particles of each sample cutting tool consisted of titanium, silicon, carbon, and nitrogen.

[0112] <Crystal structure of hard particles> The crystalline structure of the hard particles in the first layer of each cutting tool sample was confirmed by selected area electron diffraction pattern analysis. The results are shown in Table 3. In Table 3, "cubic" indicates that the hard particles have a cubic structure. In Table 3, "amorphous" indicates that the hard particles have an amorphous structure.

[0113] <First layer organization> In the first layer of each sample cutting tool, the percentage (N1 / N) × 100 of the number N1 of first hard particles with an aspect ratio of 3 or more relative to the number N of all hard particles constituting the first layer was measured. The specific measurement method is as described in embodiment 1. If the value of the percentage (N1 / N) × 100 is 60% or more, the first layer is determined to have a columnar structure, and if the value of the percentage (N1 / N) × 100 is less than 60%, the first layer is determined to be composed of granular crystals. The results are shown in Table 3.

[0114] <Composition of the first layer> In each sample cutting tool, the number of titanium atoms in the first layer, N Ti and the number of silicon atoms, N Si The number of silicon atoms, N, Si Ratio of N Si / (N Ti +N Si ) and the number of carbon atoms N C and the number of nitrogen atoms, N N The number of carbon atoms, N, C Ratio of N C / (N C +N N ) was measured by TEM-EDX. The specific measurement method is as described in embodiment 1. The results are shown in Table 1.

[0115] <Composition of the first unit layer and the second unit layer> For each sample of hard particles of cutting tools, five layers of the first unit layer and five layers of the second unit layer were arbitrarily selected, and the composition of each unit layer was specified. The composition of the first unit layer was Ti (1-x1) Si x1 C y1 N (1-y1) , and the composition of the second unit layer Ti (1-x2) Si x2 C y2 N (1-y2) The x1, x2, y1, and y2 in the above formula were obtained. The specific confirmation method is as described in embodiment 1. The results are shown in Table 4. Sample 1-5 does not have a laminated structure, so it is marked with "-".

[0116] <Average thickness of first unit layer and average thickness of second unit layer> For each sample of hard particles of the cutting tool, the average thickness d1 of the first unit layer and the average thickness d2 of the second unit layer were measured. The specific measurement method was as described in embodiment 1. The results are shown in Table 4. Based on the obtained results, the average total thickness of adjacent first unit layers and second unit layers was calculated. The results are shown in the "d1 + d2" column of Table 4.

[0117] [Table 3]

[0118] [Table 4]

[0119] <Cutting test> Cutting was performed using the cutting tools of each sample under the following cutting conditions, and the cutting time until the flank wear amount reached 0.3 mm was measured. The longer the cutting time, the longer the tool life. The results are shown in Table 5.

[0120] <Cutting conditions> Work material: SCM415 round bar material Holder: DCLNR2525M12 Insert: CNMG120408N-GU Cutting speed Vc:300m / min Feed: 0.3 mm / rev Cutting depth ap: 1.5 mm Cutting fluid: Yes (WET)

[0121] [Table 5]

[0122] <Consideration> The cutting tools of Samples 1 to 17 correspond to Examples, and the cutting tools of Samples 1-1 to 1-6 correspond to Comparative Examples. It was confirmed that the cutting tools of the Examples had a longer tool life than the cutting tools of the Comparative Examples. The cutting tools of the Examples had excellent hardness and oxidation resistance, and the sliding properties of the first unit layer were improved, so that the occurrence of welding was suppressed and wear caused by welding was also suppressed.

[0123] Although the embodiments and examples of the present disclosure have been described above, it is intended from the beginning 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 limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments and examples, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0124] 1 cutting tool, 10 substrate, 11 first layer, 12 second layer, 13 third layer, 15 coating, 50 CVD apparatus, 52 substrate setting jig, 53 reaction vessel, 54 temperature control device, 55 first gas flow path, 55a first injection hole, 56 nozzle, 57 second gas flow path, 57a second injection hole, 58 third gas flow path, 58a third injection hole, 59 exhaust pipe, 60 exhaust port.

Claims

1. A cutting tool comprising a base material and a coating disposed on the base material, The coating includes a first layer, The aforementioned first layer consists of a plurality of hard particles, The hard particles consist of titanium, silicon, carbon, and nitrogen. The hard particles have a cubic crystal structure, The aforementioned first layer is a columnar structure, In the above layer, the number of titanium atoms N Ｔｉ and the number of silicon atoms N Ｓｉ The number of silicon atoms N relative to the total Ｓｉ Ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ The average of ) is between 0.01 and 0.

10. In the first layer, the number of carbon atoms N Ｃ and the number of nitrogen atoms N Ｎ The ratio N of the number of carbon atoms N Ｃ to the total of Ｃ N / (N Ｃ + N Ｎ ) has an average of 0.≥ 60 and ≤ 0.85, The hard particles have a laminated structure in which a first unit layer and a second unit layer are alternately stacked. Each of the first and second unit layers consists of titanium, silicon, carbon, and nitrogen. The ratio x1 of the number of silicon atoms to the sum of the number of titanium atoms and silicon atoms in the first unit layer is greater than the ratio x2 of the number of silicon atoms to the sum of the number of titanium atoms and silicon atoms in the second unit layer. A cutting tool wherein the ratio y1 of the number of carbon atoms to the sum of the number of carbon atoms and nitrogen atoms in the first unit layer is greater than the ratio y2 of the number of carbon atoms to the sum of the number of carbon atoms and nitrogen atoms in the second unit layer.

2. The average thickness of the first unit layer is 2 nm or more and 15 nm or less. The cutting tool according to claim 1, wherein the average thickness of the second unit layer is 2 nm or more and 15 nm or less.

3. The cutting tool according to claim 1 or claim 2, wherein the average thickness of the sum of adjacent first unit layers and second unit layers is 4 nm or more and 30 nm or less.

4. The cutting tool according to claim 1 or claim 2, wherein the thickness of the first layer is 1.0 μm or more and 15 μm or less.

5. The coating includes a second layer disposed between the substrate and the first layer. The second layer consists of a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, and an Al layer. ２ O ３ A cutting tool according to claim 1 or claim 2, comprising at least one selected from the group consisting of layers.

6. The coating includes a third layer disposed on the surface side of the first layer of the coating, The third layer consists of a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, and an Al layer. ２ O ３ A cutting tool according to claim 1 or claim 2, which is a layer.

7. The aforementioned x1 is 0.01 or more and 0.11 or less. The cutting tool according to claim 1 or claim 2, wherein y1 is 0.60 or more and 0.85 or less.

8. The difference between x1 and x2 is 0.01 or more and 0.07 or less. The cutting tool according to claim 1 or claim 2, wherein the difference between y1 and y2 is 0.01 or more and 0.10 or less.

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