Cutting tool

Abstract

This cutting tool comprises a substrate and a film disposed on the substrate, wherein: the film includes a first layer; the first layer is composed of a plurality of hard particles; the hard particles are formed of titanium, silicon, carbon, and nitrogen; the hard particles have a cubic crystal structure; the first layer has a columnar structure; the average of the ratio NSi / (NTi+NSi) of the number NSi of silicon atoms to the total of the number NTi of titanium atoms and the number NSi of the silicon atoms in the first layer is 0.010-0.10; the hard particles have a lamellar structure in which the content of the silicon periodically changes; and, in a first graph which shows the results, obtained by performing line analysis using an energy dispersive X-ray spectrometer attached to a transmission electron microscope along the lamination direction of the lamellar structure in the hard particles, in a coordinate system in which an X axis is a distance from an arbitrary point P1 in the hard particles and a Y axis is the ratio NSi / (NTi+NSi), each cycle of the ratio NSi / (NTi+NSi) includes a first minimum value, a first maximum value, a second minimum value, a second maximum value, and a third minimum value along the positive direction of the X axis, and the average of the second minimum value is larger than the average of the first minimum value and the third minimum value.

Description

cutting tools

[0001] The present disclosure relates to cutting tools.

[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 the cutting tools (for example, see Patent Document 1).

[0003] International Publication No. 2022 / 230363

[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 0.010 or more and 0.10 or less, the hard particles have a lamellar structure in which the silicon content changes periodically, and the results obtained by performing line analysis of the hard particles along the lamellar structure stacking direction using an energy dispersive X-ray spectrometer attached to a transmission electron microscope are plotted as follows: the X axis represents the distance from an arbitrary point P1 in the hard particle, and the Y axis represents the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) in the first graph shown in the coordinate system where the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes, along the positive direction of the X-axis, a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum, and an average of the second minimums is greater than an average of the first minimum and the third minimum.

[0005] FIG. 1 is a schematic diagram showing an example of a cross section of the cutting tool according to the first embodiment. FIG. 2 is a schematic diagram showing another example of a cross section of the cutting tool according to the first embodiment. FIG. 3 is a schematic diagram showing another example of a cross section of the cutting tool according to the first embodiment. FIG. 4 is a schematic diagram showing another example of a cross section of the cutting tool according to the first embodiment. FIG. 5 is an example of a first graph obtained for the cutting tool according to the first embodiment. FIG. 6 is a schematic cross-sectional view of an example of a CVD apparatus used in a manufacturing method for a cutting tool according to the second embodiment. FIG. 7 is an enlarged view of region VII in FIG. 6. FIG. 8 is a cross-sectional view of nozzle 56 taken along line XVII-XVII in FIG. 7. FIG. 9 is a cross-sectional view of the nozzle used in Samples 1-3.

[0006] [Problem to be Solved by the Present Disclosure] Cutting tools having a high-hardness TiSiCN film have excellent wear resistance. However, when such cutting tools are used to perform intermittent cutting of chromium-molybdenum steel (SCM435), the tool life may be shortened due to damage to the coating. Therefore, there is a demand for cutting tools that can have a long tool life, especially when used for intermittent cutting of 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 interrupted cutting of chromium-molybdenum steel.

[0008] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a cutting tool that can have a long tool life, particularly when used for interrupted cutting of chromium-molybdenum steel.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. (1) A cutting tool of 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 NＳｉ Ratio of N Ｓｉ / (N Ｔｉ +N Ｓｉ ) is 0.010 or more and 0.10 or less, the hard particles have a lamellar structure in which the silicon content changes periodically, and the results obtained by performing line analysis of the hard particles along the lamellar structure stacking direction using an energy dispersive X-ray spectrometer attached to a transmission electron microscope are plotted as follows: the X axis represents the distance from an arbitrary point P1 in the hard particle, and the Y axis represents the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) in the first graph shown in the coordinate system where the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes, along the positive direction of the X-axis, a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum, and an average of the second minimums is greater than an average of the first minimum and the third minimum.

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

[0011] (2) In the above (1), the periodic width of the first graph in the direction along the X-axis may be 3 nm or more and 20 nm or less, which further improves the tool life.

[0012] (3) In the above (1) or (2), the difference between the average of the first maximum value and the second maximum value and the average of the second minimum value may be 0.005 or more and 0.040 or less, thereby further improving 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, and the second layer is 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 O３ The layer may include at least one selected from the group consisting of:

[0015] This further improves the tool life.

[0016] (6) In any one of the above (1) to (5), the coating includes a third layer disposed on the outermost surface of the coating, and the third layer is a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, or an Al ２ O ３ It may be a layer.

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

[0018] [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.

[0019] In the present disclosure, the notation in the form of "A to B" means A or more and B or less, and 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 listed as the lower limit and the upper limit of a numerical range, the combination of any one numerical value listed as the lower limit and any one numerical value listed as the upper limit is also considered to be disclosed.

[0022] 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.

[0023] [Embodiment 1: Cutting Tool] A cutting tool according to one embodiment of the present disclosure (hereinafter also referred to as "this embodiment") will be described with reference to Figures 1 to 4. The cutting tool 1 of this embodiment is a cutting tool 1 including a substrate 10 and a coating disposed on the substrate 10, wherein the coating 15 includes a first layer 11, the first layer 11 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 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 The hard particles have a lamellar structure in which the silicon content changes periodically, and the results obtained by performing line analysis of the hard particles along the lamellar structure stacking direction using an energy dispersive X-ray spectrometer attached to a transmission electron microscope are plotted as follows: the X axis represents the distance from an arbitrary point P1 in the hard particle; the Y axis represents the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ), the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes, along the positive direction of the X-axis, a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum, and the average of the second minimums is greater than the average of the first minimum and the third minimum.

[0024] The cutting tool of this embodiment has a long tool life, especially when used for interrupted cutting of chromium-molybdenum steel. The reason for this is not clear, but is presumed to be as follows.

[0025] (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.

[0026] (ii) The hard particles of the cutting tool of this embodiment have a lamellar structure in which the silicon content changes periodically, which causes lattice distortion due to the change in silicon content within the hard particles, and even if cracks occur during cutting, the propagation of the cracks in the lamellar structure is suppressed.

[0027] (iii) In the first graph of the hard particles of the cutting tool of this embodiment, the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum along the positive direction of the X-axis, and the average of the second minimum is greater than the average of the first minimum and the third minimum. Ｓｉ / (N Ｔｉ +N Ｓｉ ) is the first minimum value and the third minimum value at which the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ The lattice strain due to the difference between the first maximum value and the second maximum value, which are relatively large, is moderately alleviated, and the propagation of cracks in the direction perpendicular to the lamellar structure stacking direction is suppressed. Therefore, the cutting tool has excellent fracture resistance.

[0028] <Cutting Tool> 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 portion of the substrate involved in cutting, or may cover the entire surface of the substrate. The portion of the substrate 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 has a partially different configuration.

[0029] <Type of Cutting Tool> 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, or the like.

[0030] <Substrate> In this embodiment, the substrate can be a conventionally known one.For example, the material of the substrate can be cemented carbide (for example, WC-based cemented carbide containing tungsten carbide and cobalt, the cemented carbide 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.

[0031] 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.

[0032] The surface of the substrate may be modified. For example, in the case of cemented carbide, a de-β layer may be formed on the surface, and in the case of cermet, a surface-hardened layer may be formed. Even if the surface of the substrate is modified, the desired effect can be achieved.

[0033] 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.

[0034] <Coating> <Configuration of Coating> 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.

[0035] 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 .

[0036] As shown in FIG. 3 , the coating 15 of the cutting tool 1 may include a third layer 13 disposed on the outermost surface of the coating 15 .

[0037] The first, second and third layers will be described in detail below.

[0038] <Coating Thickness> In this embodiment, the coating thickness may be 1 μm or more and 30 μm or less. Here, the coating thickness refers to the thickness of the entire coating. When the coating thickness is 1 μm or more, excellent wear resistance can be obtained. On the other hand, when the coating thickness 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 coating thickness may be 5 μm or more and 25 μm or less, or 8 μm or more and 20 μm or less.

[0039] In the present disclosure, the thickness of the 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.

[0040] The measurement sample was observed at a magnification of 10,000 times, 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.

[0041] 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.

[0042] <First Layer> <Composition of 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 0.010 or more and 0.10 or less. Ｓｉ / (N Ｔｉ +N Ｓｉ When the average of N is 0.010 or more, the wear resistance is improved. Ｓｉ / (N Ｔｉ +N Ｓｉ When the average of the ratios (R) and (C) is 0.10 or less, good welding resistance can be obtained.

[0043] NＳｉ / (N Ｔｉ +N Ｓｉ The average of (a) may be 0.02 or more and 0.09 or less, 0.02 or more and 0.07 or less, or 0.02 or more and 0.05 or less.

[0044] In the present disclosure, N in the first layer Ｓｉ / (N Ｔｉ +N Ｓｉ The average of the saturation and saturation values ​​is determined by the following procedure.

[0045] (A1) The cutting tool is cut out 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 subjected to focused ion beam processing (hereinafter also referred to as "FIB processing") to make the cross section mirror-finished.

[0046] (A2) A rectangular analysis is performed on the cross section of the first layer using an energy dispersive X-ray spectrometer (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 ) is calculated from the N of the three measurement areas. Ｓｉ / (N Ｔｉ +N Ｓｉ ) is calculated. The average is calculated based on the N Ｓｉ / (N Ｔｉ +N Ｓｉ ) corresponds to the average.

[0047] 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.

[0048] <<Structure of First Layer>> In this embodiment, the first layer has a columnar structure. This makes the first layer resistant to stress in the shear direction 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.

[0049] 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.

[0050] (B1) The cutting tool is cut out with a diamond wire along the normal to the surface of the cutting tool to expose a cross section of the first layer. The exposed cross section is subjected to FIB processing to make the cross section mirror-finished.

[0051] (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: 1.8 nA Probe current: 60 μm (with HC) Exp: Long 0.03 s Binning: 8 × 8 WD: 15 mm 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

[0052] (B3) 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 interpolation) 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).

[0053] (B4) The EBSD analysis results are analyzed using commercially available software (product name: "OIM7.1" manufactured by TSL Solutions Co., Ltd.), and an IPF map (Inverse Pole Tigre map) of the analysis region is created. 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 crystal grain, and the orientation of each crystal grain is indicated by a different color.

[0054] (B5) Using the above software ("OMI7.1"), the aspect ratio is measured for 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 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 is present in the IPF map of the analysis region and hard particles whose at least a portion is present in the IPF map of the analysis region.

[0055] (B6) Calculate the percentage (n1 / n) × 100 of the number n1 of first hard particles having 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 having 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.

[0056] 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.

[0057] <Hard Particles> <Composition of Hard Particles> 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 can be, for example, 0.5 atomic % or less. The content of inevitable impurity elements in the hard particles is measured by TEM-EDX.

[0058] <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 achieve 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.

[0059] First Graph: In this embodiment, the hard particles have a lamellar structure in which the silicon content changes periodically. The results obtained by performing line analysis of the hard particles along the lamellar structure stacking direction using an energy dispersive X-ray spectrometer (TEM-EDX) attached to a transmission electron microscope are shown in the graph, where the X axis represents the distance from an arbitrary point P1 in the hard particle and the Y axis represents the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ), the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ Each of the periods of the graph includes a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum along the positive direction of the X-axis, and the average of the second minimum is greater than the average of the first minimum and the third minimum. The first minimum, the first maximum, the second minimum, the second maximum, and the third minimum are each in a ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ The first graph is obtained by the following procedure.

[0060] (C1) The cutting tool is cut out with a diamond wire along the normal to the surface of the cutting tool to expose a cross section of the first layer. The exposed cross section is subjected to FIB processing to make the cross section mirror-finished.

[0061] (C2) The FIB-processed cross section is observed using a bright-field scanning electron microscope (BF-SEM) to identify one hard particle, and then a BF-STEM image of the identified hard particle is obtained.

[0062] (C3) In the 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 white layers (hereinafter also referred to as "white layers") and 10 or more layers of black layers (hereinafter also referred to as "black layers") are stacked. The white layers are areas with a low silicon content. The black layers are areas with a high silicon content.

[0063] (C4) The stacking direction of the white layer and the black layer is identified within the measurement region in the BF-STEM image. Specifically, the electron beam diffraction pattern of the selected visual field region is superimposed on the stacking orientation of the white layer and the black layer, and the stacking direction is identified from the orientation indicated by the diffraction spots. This stacking direction corresponds to the stacking direction of the lamellar structure.

[0064] (C5) In the measurement area in the BF-STEM image, line analysis is performed by TEM-EDX along the lamellar structure stacking direction 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.

[0065] (C6) The results of the line analysis are shown as follows: the X axis represents the distance from an arbitrary point P1 in the hard particle, and the Y axis represents the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) to create a first graph.

[0066] In the first graph, if maximum and minimum values ​​alternate with an increase in distance from point P1, the hard particles are determined to have a lamellar structure in which the silicon content changes periodically.

[0067] 5 is an example of a first graph obtained in this embodiment. In the first graph of FIG. 5, the X axis represents the distance from an arbitrary point P1 in the hard particle, and the Y axis represents the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ 5, the first graph obtained in this embodiment shows the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) are relatively smallest among the minimum values ​​a1 to a8, and among the minimum values ​​a1 to a8, the intervals d1 to d7 between adjacent minimum values ​​are each smaller than the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) corresponds to one period.

[0068] Ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum along the positive direction of the X-axis. Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes, along the positive direction of the X-axis, a minimum value a1, a maximum value b1, a minimum value c1, a maximum value b2, and a minimum value a2. The minimum value a1 corresponds to the first minimum value, the maximum value b1 corresponds to the first maximum value, the minimum value c1 corresponds to the second minimum value, the maximum value b2 corresponds to the second maximum value, and the minimum value a2 corresponds to the third minimum value. Note that the minimum value a2 corresponds to the third minimum value in one period d1, and to the first minimum value in one period d2.

[0069] In the present disclosure, the average of the second minimum value and the average of the first minimum value and the third minimum value are calculated by identifying any five adjacent periods in the first graph and based on the second minimum value, the first minimum value, and the third minimum value included in the five periods.

[0070] The average of the first maximum value and the second maximum value may be 0.010 or more and 0.120 or less, 0.020 or more and 0.110 or less, or 0.030 or more and 0.100 or less.

[0071] The average of the second minimum values ​​may be 0.008 or more and 0.100 or less, 0.010 or more and 0.090 or less, or 0.020 or more and 0.080 or less.

[0072] The average of the first minimum value and the third minimum value may be 0.003 or more and 0.090 or less, 0.005 or more and 0.080 or less, or 0.010 or more and 0.070 or less.

[0073] The difference between the average of the first maximum and the second maximum and the average of the second minimum may be 0.005 to 0.040, 0.010 to 0.040, or 0.010 to 0.025, which makes it easier to obtain the effect of relaxing lattice strain due to the presence of the second minimum.

[0074] The difference between the average of the first minimum and third minimum and the average of the first maximum and second maximum may be 0.007 to 0.050, 0.010 to 0.050, or 0.010 to 0.030, which makes it easier to obtain the effect of suppressing crack growth due to lattice distortion caused by changes in silicon content.

[0075] The above-mentioned average of the first maximum and second maximum values, the average of the second minimum values, the average of the first minimum values ​​and the third minimum values, the difference between the average of the first maximum and second maximum values ​​and the average of the second minimum values, and the difference between the average of the first minimum values ​​and the third minimum values ​​and the average of the first maximum values ​​and the second maximum values ​​can be any combination of the above ranges.

[0076] In the hard particle, the region near the first minimum and the third minimum is a layer with the relatively lowest silicon content (hereinafter also referred to as a "low-silicon layer"), the region near the first maximum and the second maximum is a layer with the relatively highest silicon content (hereinafter also referred to as a "high-silicon layer"), and the region near the second minimum can be expressed as a medium-silicon layer having a silicon concentration between the high-silicon layer and the low-silicon layer. That is, one period of the lamellar structure of the hard particle can be expressed as including, along the stacking direction of the lamellar structure, a low-silicon layer, a high-silicon layer, a medium-silicon layer, a high-silicon layer, and a low-silicon layer.

[0077] In this embodiment, the periodic width along the X-axis of the first graph may be 3 nm to 20 nm. This makes it easier to maintain lattice strain within the hard particles, further suppresses crack propagation in the coating, and further improves the chipping resistance of the cutting tool. The periodic width of the silicon concentration may be 3 nm to 15 nm, or 5 nm to 10 nm.

[0078] In the present disclosure, the period width corresponds to the average of the period widths of any five adjacent periods in the first graph.

[0079] As long as measurements are made on the same sample, it has been confirmed that there is almost no variation in the measurement results for each of the above items even when measurements are made multiple times while changing the hard particles specified in (C2) above.

[0080] <<Thickness of First Layer>> The thickness of the first layer of 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.

[0081] <Second Layer> The coating of this embodiment may include a second layer disposed between the substrate and the first layer. The second layer may be a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, or an Al ２ O ３ The layer may include at least one selected from the group consisting of:

[0082] By disposing a TiN layer, a TiC layer, a TiCN layer, a TiBN layer or a TiCNO layer directly on the substrate as the second layer, it is possible to improve the adhesion between the substrate and the coating. ２ O ３ The use of the second layer can improve the oxidation resistance of the coating. 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.

[0083] <Third Layer> The coating of the first embodiment may include a third layer disposed on the outermost surface of the coating. The third layer may be a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, or an Al ２ O ３ The TiN layer has a clear color (golden), so when used as the third layer, it has the advantage of making it easy to identify the used portion of the cutting tool after cutting. By using a TiC layer, a TiCN layer, a TiBN layer, or a TiCNO layer as the third layer, the sliding properties of the coating can be improved. When an Al layer is used as the third layer, ２ O ３ By using the layer, the oxidation resistance of the coating can be improved.

[0084] 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.

[0085] [Embodiment 2: Manufacturing method of cutting tool] A description will be given of an example of a manufacturing method of the cutting tool according to embodiment 1. The manufacturing method of 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.

[0086] <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.

[0087] <Second Step> 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. 6. A plurality of substrate setting jigs 52 holding the substrates 10 can be installed 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.

[0088] 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, for injecting the gas that has passed through the gas flow paths.

[0089] 8 is a cross-sectional view of the nozzle 56 taken along line XVII-XVII in FIG. 7. As shown in FIG. 8, 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. The first gas flow passage 55 is a passage for discharging SiCl ４ The gas passes through the second gas flow passage 57. ４ The gas passes through the third gas flow passage 58. ３ CN gas passes through.

[0090] The first gas flow passage 55 communicates with two first injection holes 55 a and one second injection hole 55 b. The gas that has passed through the first gas flow passage 55 is injected toward the substrate from the first injection holes 55 a and the second injection holes 55 b. The diameter of the first injection holes 55 a is larger than the diameter of the second injection holes 55 b.

[0091] The second gas flow passage 57 communicates with the third injection hole 57a. The gas that has passed through the second gas flow passage 57 is injected from the third injection hole 57a toward the substrate. The third gas flow passage 58 communicates with the fourth injection hole 58a. The gas that has passed through the third gas flow passage 58 is injected from the fourth injection hole 58a toward the substrate.

[0092] As a carrier gas, H ２ Gas, N ２ A gas, Ar gas, or the like may be used. The carrier gas is injected from each of the first injection hole, the second injection hole, the third injection hole, and the fourth injection hole. In the present disclosure, a gas containing a raw material gas and a carrier gas is referred to as a reaction gas.

[0093] When forming the first layer, the nozzle is rotated while the film is formed. ４The first injection hole 55a and the second injection hole 55b through which the gas is injected have different hole diameters. Therefore, the hard particles contained in the first layer can have a lamellar structure in which the silicon content changes periodically. Furthermore, in the first graph obtained for the hard particles, the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes, along the positive direction of the X-axis, a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum, and the average of the second minimums is greater than the average of the first minimum and the third minimum.

[0094] 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 140 hPa. The thickness of the first layer can be controlled by adjusting the flow rate of the source gas and the deposition time. The periodic width in the direction along the X-axis of the first graph can be controlled by adjusting the rotation speed of the nozzle and the deposition time.

[0095] During the formation of the first layer, the total flow rate of the reaction 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).

[0096] 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.

[0097] (Other Steps) Next, the substrate on which the coating has been formed is cooled. The cooling rate does not exceed, for example, 5°C / min, and the cooling rate slows as the temperature of the substrate decreases.

[0098] 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.

[0099] The cutting tool of the first embodiment can be obtained by the above-described manufacturing method.

[0100] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0101] <Preparation of 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.

[0102] <Formation of Coating> 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 Tables 1 and 2. A "-" in the table indicates that no layer is present. The first layer is composed of a plurality of hard particles, and the hard particles are composed of titanium, silicon, carbon, and nitrogen. The second and third layers are layers formed by conventionally known CVD methods.

[0103]

[0104]

[0105] The first layer of each sample was formed using the CVD apparatus shown in Figure 6. For samples with "A" in the "Type" column of "Nozzle" in Tables 3 and 4, a nozzle 56 shown in Figure 8 was used. The nozzle 56 is provided with a first gas flow path 55, a second gas flow path 57, and a third gas flow path 58. The first gas flow path 55 was filled with SiCl ４ The gas passes through the second gas flow passage 57. ４ The gas passes through the third gas flow passage 58. ３ CN gas passes through.

[0106] The first gas flow path 55 communicates with two first injection holes 55a and one second injection hole 55b. The gas that passes through the first gas flow path 55 is injected toward the substrate from the first injection holes 55a and the second injection holes 55b. The diameters φ of the first injection holes 55a and the second injection holes 55b are shown in Tables 3 and 4.

[0107] The second gas flow passage 57 communicates with the third injection hole 57a. The gas that has passed through the second gas flow passage 57 is injected from the third injection hole 57a toward the substrate. The third gas flow passage 58 communicates with the fourth injection hole 58a. The gas that has passed through the third gas flow passage 58 is injected from the fourth injection hole 58a toward the substrate.

[0108] For the samples in Tables 3 and 4 where "B" is listed in the "Type" column of "Nozzle," a nozzle 56 shown in FIG. 9 was used. The nozzle 56 is provided with a first gas flow path 55, a second gas flow path 57, and a third gas flow path 58. The first gas flow path 55 was used to fill the SiCl ４ The gas passes through the second gas flow passage 57. ４ The gas passes through the third gas flow passage 58. ３ CN gas passes through.

[0109] The first gas flow passage 55 communicates with one second injection hole 55b. The gas that has passed through the first gas flow passage 55 is injected toward the substrate from the second injection hole 55b. The second gas flow passage 57 communicates with a third injection hole 57a. The gas that has passed through the second gas flow passage 57 is injected toward the substrate from the third injection hole 57a. The third gas flow passage 58 communicates with a fourth injection hole 58a, and the gas that has passed through the third gas flow passage 58 is injected toward the substrate from the fourth injection hole 58a.

[0110] For each sample, the ratio of the volume flow rate V of the entire reaction gas to the volume flow rate of SiCl ４ The percentage of the volume flow rate V1 (V1 / V) x 100, the nozzle rotation speed, the substrate temperature and the pressure are shown in Tables 3 and 4.

[0111] The substrate was then cooled to obtain a cutting tool for each sample.

[0112]

[0113]

[0114] <Configuration of First Layer> When the first layer of each sample cutting tool was observed with a bright field scanning electron microscope (BF-SEM), it was confirmed that the first layer was made up of a plurality of hard particles.

[0115] <Crystalline 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 Tables 5 and 6. In the tables, "cubic" indicates that the hard particles have a cubic structure. In the tables, "cubic + amorphous" indicates that the hard particles have a cubic structure containing amorphous material.

[0116] <Structure of First Layer> In the first layer of each cutting tool sample, the percentage (N1 / N) × 100 of the number N1 of first hard particles having 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 Tables 5 and 6.

[0117] <Composition of First Layer> In each sample cutting tool, the number of titanium atoms N 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 ) was measured by TEM-EDX. The specific measurement method is as described in Embodiment 1. The results are shown in Tables 1 and 2.

[0118] <Presence or Absence of Lamellar Structure> The hard particles of each sample cutting tool were composed of titanium, silicon, carbon, and nitrogen. The hard particles of each sample cutting tool were checked for the presence or absence of a lamellar structure in which the silicon content periodically changes. The specific checking method was as described in embodiment 1. The results are shown in Tables 5 and 6.

[0119] <First Graph> Line analysis was performed using TEM-EDX on the hard particles of the cutting tools of each sample to obtain the first graph. Tables 5 and 6 show the "average of the first and third minimum values," "average of the second minimum value," "average of the first and second maximum values," and the "period width" along the X-axis of the first graph for each sample. Note that in Samples 1-2 and 2-2, only one maximum value (first maximum value) was present between the two minimum values ​​(within one period) with the lowest silicon content, and neither a second minimum value nor a second maximum value was present. Therefore, the "average of the first and second maximum values" column in the table shows the average silicon content of the first maximum values.

[0120]

[0121]

[0122] <Cutting test> Using the cutting tool of each sample, cutting was performed under the cutting conditions described in Cutting Test 1 or Cutting Test 2 below, and the cutting time until the flank damage width reached 0.3 mm was measured. A longer cutting time indicates a longer tool life. The results are shown in Tables 7 and 8.

[0123] <Cutting test 1: Samples 1 to 15, Samples 1-1 to 1-3> Workpiece: SCM435 grooved round bar; Holder: DCLNR2525M12; Insert: CNMG120408N-GU; Cutting speed Vc: 200 m / min; Feed f: 0.3 mm / rev; Depth of cut ap: 1.5 mm; Cutting fluid: Yes (wet)

[0124]

[0125] <Cutting test 2: Samples 21 to 35, Samples 2-1 to 2-3> Workpiece: SCM435 grooved round bar; Holder: DCLNR2525M12; Insert: CNMG120408N-GU; Cutting speed Vc: 400 m / min; Feed f: 0.15 mm / rev; Depth of cut ap: 1.5 mm; Cutting fluid: Yes (WET)

[0126]

[0127] <Considerations based on cutting condition 1> The cutting tools of Samples 1 to 15 correspond to Examples, and the cutting tools of Samples 1-1 to 1-3 correspond to Comparative Examples. The results of Cutting Test 1 confirmed that the cutting tools of the Examples had longer tool life than the cutting tools of the Comparative Examples, particularly in the intermittent cutting of chromium-molybdenum steel, which is relatively prone to welding at low speeds.

[0128] For sample 1-2, there was no second minimum value within one cycle in graph 1. For this reason, it is presumed that the effect of alleviating lattice strain due to the difference between the first and third minimum values ​​and the first maximum value was difficult to obtain, and cracks were likely to propagate in a direction perpendicular to the lamellar structure stacking direction, resulting in a shortened tool life.

[0129] <Considerations based on cutting condition 2> The cutting tools of Samples 21 to 35 correspond to Examples, and the cutting tools of Samples 2-1 to 2-3 correspond to Comparative Examples. The results of Cutting Test 2 confirmed that the cutting tools of the Examples had longer tool life than the cutting tools of the Comparative Examples, particularly in the intermittent cutting of chromium-molybdenum steel, which is susceptible to wear at high speeds.

[0130] For sample 2-2, there was no second minimum value within one cycle in graph 1. For this reason, it is presumed that the effect of alleviating lattice strain due to the difference between the first and third minimum values ​​and the first maximum value was difficult to obtain, and cracks were likely to propagate in a direction perpendicular to the lamellar structure stacking direction, resulting in a shortened tool life.

[0131] 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.

[0132] 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, 55b Second injection hole, 56 Nozzle, 57 Second gas flow path, 57a Third injection hole, 58 Third gas flow path, 58a Fourth injection hole, 59 Exhaust pipe, 60 Exhaust port.

Claims

1. A cutting tool comprising a substrate and a coating disposed on the substrate, wherein the coating includes a first layer, wherein the first layer is 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, and the first layer has a columnar structure, and wherein the number of titanium atoms in the first layer is 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 0.010 or more and 0.10 or less, the hard particles have a lamellar structure in which the silicon content changes periodically, and the results obtained by performing line analysis of the hard particles along the lamellar structure stacking direction using an energy dispersive X-ray spectrometer attached to a transmission electron microscope are plotted as follows: the X axis represents the distance from an arbitrary point P1 in the hard particle, and the Y axis represents the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ In the first graph shown in a coordinate system where the ratio N Ｓｉ / (N Ｔｉ +N Ｓｉ ) includes, along the positive direction of the X-axis, a first minimum, a first maximum, a second minimum, a second maximum, and a third minimum, and an average of the second minimums is greater than an average of the first minimum and the third minimum.

2. The cutting tool according to claim 1, wherein the periodic width of the first graph in the direction along the X-axis is 3 nm or more and 20 nm or less.

3. A cutting tool according to claim 1 or 2, wherein the difference between the average of the first maximum value and the second maximum value and the average of the second minimum value is 0.005 or more and 0.040 or less.

4. A cutting tool according to any one of claims 1 to 3, 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, and the second layer is 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 The cutting tool according to claim 1 , comprising at least one selected from the group consisting of layers.

6. The coating includes a third layer disposed on the outermost surface of the coating, and the third layer is a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, a TiCNO layer, or an Al ２ O ３ 6. The cutting tool of claim 1, wherein the cutting tool is a layer.

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