Cutting tool

Abstract

A cutting tool provided with a base material and a coating film provided on the base material, wherein the coating film includes a hard particle layer composed of a plurality of hard particles including titanium, silicon, carbon, and nitrogen, in the hard particles, the concentration of the silicon periodically changes along a first direction set within the hard particles, and the orientation of the hard particle layer is (220) orientation.

Description

Technical Field

[0001] This disclosure relates to cutting tools. This application claims priority based on Japanese Patent Application No. 2021-078024, filed on April 30, 2021. The entire contents of that Japanese patent application are incorporated herein by reference. Background Technology

[0002] In the past, in order to improve the wear resistance of cutting tools, cutting tools with TiSiCN films formed on the substrate were developed.

[0003] Patent document 1 discloses a nanocomposite coating comprising TiC fabricated by thermal CVD. x N 1-x Nanocrystalline layers and amorphous SiC x N y The second phase.

[0004] Non-patent document 1 discloses a TiSiCN coating, which is composed of a nanocomposite structure formed by PVD.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2015-505902

[0008] Non-patent literature

[0009] Non-patent document 1: Shinya Imamura et al., "Properties and cutting performance of AlTiCrN / TiSiCN bilayer coatings deposited by cathodic-arc ion plating", Surface and Coatings Technology, 202, (2007), 820-825 Summary of the Invention

[0010] The cutting tool disclosed herein includes a substrate and a coating disposed on said substrate.

[0011] The coating comprises a rigid granular layer.

[0012] The hard particle layer is composed of multiple hard particles containing titanium, silicon, carbon, and nitrogen.

[0013] In the hard particles, the concentration of silicon varies periodically along a first direction defined within the hard particles.

[0014] The orientation of the hard particle layer is (220). Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing an example of a cross-section of the cutting tool according to Embodiment 1.

[0016] Figure 2 This is a schematic diagram showing another example of a cross-section of the cutting tool involved in Embodiment 1.

[0017] Figure 3 This is a schematic diagram showing another example of a cross-section of the cutting tool involved in Embodiment 1.

[0018] Figure 4 This is a schematic diagram showing another example of a cross-section of the cutting tool involved in Embodiment 1.

[0019] Figure 5 This is a diagram illustrating an example of a bright-field scanning transmission electron microscope (BF-STEM) image (magnification: 100,000x) of a cross-section of the hard phase granular layer of the cutting tool according to Embodiment 1.

[0020] Figure 6 This is a diagram illustrating an example of a bright-field scanning transmission electron microscope (BF-STEM) image (magnification: 2 millionx) of a cross-section of the hard phase granular layer of the cutting tool according to Embodiment 1.

[0021] Figure 7 This is an example of a graph showing the results of a line analysis of the hard particles of the cutting tool according to Embodiment 1.

[0022] Figure 8 This is a schematic cross-sectional view of an example of a CVD apparatus used in the manufacture of the cutting tool according to Embodiment 2. Detailed Implementation

[0023] [The problem this disclosure aims to solve]

[0024] In recent years, the demand for reducing manufacturing costs has been increasing, requiring cutting tools with longer tool life.

[0025] Therefore, the purpose of this disclosure is to provide a cutting tool with a long tool life.

[0026] [The Effects of This Disclosure]

[0027] According to this disclosure, it is possible to provide a cutting tool with a long tool life.

[0028] [Description of embodiments of this disclosure]

[0029] The embodiments of this disclosure are first described by listing them.

[0030] (1) The cutting tool of this disclosure has a substrate and a coating disposed on the substrate.

[0031] The coating comprises a rigid granular layer.

[0032] The hard particle layer is composed of multiple hard particles containing titanium, silicon, carbon, and nitrogen.

[0033] In the hard particles, the concentration of silicon varies periodically along a first direction defined within the hard particles.

[0034] The orientation of the hard particle layer is (220).

[0035] According to this disclosure, the cutting tool can have a long tool life.

[0036] (2) Preferably, in the hard particles, the number of silicon atoms A Si Relative to the number of atoms A of the titanium Ti With the number of atoms A of the silicon Si The total percentage {A} Si / (A Si +A Ti The average of )}×100 is above 1% and below 20%.

[0037] As a result, the tool life of cutting tools is further improved.

[0038] (3) Preferably, the average period width of the silicon concentration is 3 nm or more and 50 nm or less. As a result, the tool life of the cutting tool is further improved.

[0039] (4) Preferably, the thickness of the hard particle layer is more than 1 μm and less than 20 μm. As a result, the tool life of the cutting tool is further improved.

[0040] (5) Preferably, the substrate is made of a hard alloy comprising tungsten carbide and cobalt.

[0041] The cobalt content in the cemented carbide is more than 6% by mass and less than 11% by mass.

[0042] As a result, the tool life of cutting tools is further improved.

[0043] (6) Preferably, in the hard particles, the number of silicon atoms A Si Relative to the number of atoms A of the titanium TiWith the number of atoms A of the silicon Si The total percentage {A} Si / (A Si +A Ti The difference between the maximum and minimum values ​​of )}×100 is more than 1% and less than 38%.

[0044] As a result, the hardness and toughness of the membrane in the hard particle layer are improved.

[0045] (7) Preferably, the coating comprises a base layer disposed directly above the substrate.

[0046] The substrate layer is composed of at least one selected from the group consisting of TiN layer, TiC layer, TiCN layer, TiBN layer and Al2O3 layer.

[0047] By placing TiN, TiC, TiCN, and TiBN layers directly above the substrate as a base layer, the adhesion between the substrate and the coating can be improved. Furthermore, using an Al2O3 layer as a base layer can enhance the oxidation resistance of the coating.

[0048] (8) Preferably, the coating comprises the outermost layer disposed on the outermost surface side of the coating.

[0049] The outermost layer is composed of a layer containing more than 90% by mass of titanium carbides, titanium nitrides, or titanium borides, or an Al2O3 layer.

[0050] As the outermost layer, using a layer containing more than 90% by mass of titanium carbides, titanium nitrides, or titanium borides offers the advantage of easy corner identification (identification of used areas) of the cutting tool after cutting. Using an Al2O3 layer as the outermost layer improves the coating's oxidation resistance.

[0051] [Details of the embodiments disclosed herein]

[0052] Hereinafter, specific examples of the cutting tools of this disclosure will be described with reference to the accompanying drawings. In the drawings of this disclosure, the same reference numerals denote the same or equivalent parts. In addition, dimensional relationships such as length, width, thickness, and depth have been appropriately modified for the clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0053] In this specification, expressions such as "A~B" refer to the upper and lower limits of a range (i.e., above A and below B). If no unit is recorded in A but only in B, the unit of A is the same as the unit of B.

[0054] In this specification, when compounds are represented by chemical formulas, all conventionally known atomic ratios are included unless otherwise specified, and are not necessarily limited to atomic ratios within the stoichiometric range. For example, when referred to as "TiSiCN", the ratio of the number of atoms constituting TiSiCN includes all conventionally known atomic ratios.

[0055] [Implementation Method 1: Cutting Tool]

[0056] One embodiment of this disclosure (hereinafter also referred to as "this embodiment") includes a cutting tool comprising a substrate and a coating disposed on the substrate, wherein,

[0057] The coating contains a hard particle layer.

[0058] This hard particle layer is composed of multiple hard particles containing titanium, silicon, carbon, and nitrogen.

[0059] Within this hard particle, the concentration of silicon varies periodically along a first direction defined within the hard particle.

[0060] The orientation of the hard granular layer is (220) orientation.

[0061] The cutting tool of this embodiment can have a long tool life. The reason for this is presumably as described in (i) to (iii) below.

[0062] (i) In the cutting tool of this embodiment, the coating comprises a hard particle layer consisting of multiple hard particles comprising titanium, silicon, carbon, and nitrogen. The hard particles comprising titanium, silicon, carbon, and nitrogen have high hardness. Therefore, the hard particle layer consisting of these hard particles has high hardness and excellent wear resistance.

[0063] (ii) In the hard particles of the cutting tool of this embodiment, the concentration of silicon varies periodically along a first direction set within the hard particles. This generates strain within the hard particles, increasing the hardness of the hard particles and the hard particle layer, thereby improving the wear resistance of the cutting tool. Furthermore, due to the compositional change within the hard particles, crack propagation is suppressed, improving the cutting tool's resistance to chipping.

[0064] (iii) In the cutting tool of this embodiment, the orientation of the hard particle layer is (220). When the orientation of the hard particle layer is (220), the elastic recovery rate of the hard particle layer is improved. The cutting tool containing this hard particle layer exhibits excellent wear resistance, especially in the cutting of cast iron. This is a new insight discovered by the inventors of the present invention.

[0065] <Components of Cutting Tools>

[0066] like Figure 1As shown, the cutting tool 1 of this embodiment includes a substrate 10 and a coating 14 disposed on the substrate 10. Figure 1 In this process, the coating 14 consists only of a hard particle layer 11. Preferably, the coating 14 covers at least a portion of the cutting portion of the substrate, and more preferably, it covers the entire surface of the substrate. The cutting portion of the substrate refers to the area on the substrate surface within 500 μm of the blade tip edge. Even if a portion of the substrate is not covered by the coating or the composition of the coating is locally different, it does not depart from the scope of this disclosure.

[0067] Based on the rigid granular layer, the coating can also include other layers. For example, such as... Figure 2 As shown in the cutting tool 21, the coating 24 may also include a base layer 12 disposed between the substrate 10 and the hard particle layer 11, based on the hard particle layer 11.

[0068] like Figure 3 As shown in the cutting tool 31, the coating 34 may also include an outermost layer 13 disposed on the hard particle layer 11, based on the hard particle layer 11 and the base layer 12.

[0069] like Figure 4 As shown in the cutting tool 41, the coating 45 may include a hard particle layer 11, a base layer 12 consisting of a two-layer structure of a first base layer 12A and a second base layer 12B, and an outermost layer 13.

[0070] Types of cutting tools

[0071] The cutting tools disclosed herein may be, for example, drill bits, end mills (e.g., ball end mills), indexable cutting inserts for drill bits, indexable cutting inserts for end mills, indexable cutting inserts for milling, indexable cutting inserts for turning, metalworking saws, gear cutting tools, reamers, taps, etc.

[0072] <Substrate>

[0073] The substrate 10 includes a rake face and a flank face. Any conventionally known substrate can be used as such a substrate. For example, it is preferably a cemented carbide (e.g., a WC-based cemented carbide containing tungsten carbide and cobalt, which may contain carbonitrides such as Ti, Ta, and Nb), a cermet (with TiC, TiN, TiCN, etc. as the main components), a high-speed steel, a ceramic (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, alumina, etc.), a cubic boron nitride sintered body, or a diamond sintered body.

[0074] Among these various substrates, a substrate composed of a cemented carbide containing tungsten carbide and cobalt is preferred, wherein the cobalt content in the cemented carbide is 6% by mass or more and 11% by mass or less. This results in an excellent balance between hardness and strength at high temperatures, giving the substrate excellent properties for cutting tools used in the aforementioned applications. When using a WC-based cemented carbide as the substrate, its microstructure may include free carbon and an anomalous layer referred to as the η phase or ε phase.

[0075] Furthermore, the surface of the substrate can be modified. For example, in the case of cemented carbide, a de-β layer can be formed on its surface, and in the case of cermet, a surface-hardened layer can be formed. The substrate exhibits the desired effect even after its surface has been modified.

[0076] When the cutting tool is an indexable cutting insert, the substrate may or may not have a chip breaker. The shape of the tool tip edge can be any of the following: a sharp edge (the edge where the rake face and flank face intersect), honing (giving the sharp edge a rounded corner), a negative cutting edge (beveling), or a combination of honing and a negative cutting edge.

[0077] <Composition of the coating>

[0078] The coating in this embodiment includes a hard particle layer. Since the coating includes a hard particle layer, the coating in this embodiment may also include other layers. Examples of other layers include, for instance, a base layer and an outermost layer. Details of the hard particle layer, base layer, and outermost layer will be described later.

[0079] In this embodiment, the overall thickness of the coating is preferably 1 μm or more and 30 μm or less. When the overall thickness of the coating is 1 μm or more, it can exhibit excellent abrasion resistance. On the other hand, when the overall thickness of the coating is 30 μm or less, it can suppress the peeling or damage of the coating when large stress is applied between the coating and the substrate during intermittent processing.

[0080] The thickness of the aforementioned coating is measured, for example, by observing a cross-sectional sample parallel to the normal direction of the substrate surface using a scanning transmission electron microscope (STEM). This cross-sectional sample is a thin sheet sample processed using an ion slicer or similar device. An example of a scanning transmission electron microscope is the JEM-2100F (trademark) manufactured by Nippon Electron Ltd. The measurement conditions are set to an accelerating voltage of 200 kV and a current of 0.3 nA.

[0081] When "thickness" is mentioned in this specification, it refers to the average thickness. Specifically, the magnification of the cross-sectional sample is set to 1000x, and a rectangular measurement field of view (100 μm parallel to the substrate surface) × (the distance including the entire thickness of the coating) is set in the electron microscope image. The thickness amplitude at ten locations within this field of view is measured, and the average value is taken as the "thickness". The thickness (average thickness) of each layer described below is also measured and calculated in the same way.

[0082] It was confirmed that as long as the measurement is performed on the same sample, even if the measurement field of view is changed and the measurement is performed multiple times, the measurement results will have almost no deviation. Even if the measurement field of view is set arbitrarily, the results will not change arbitrarily.

[0083] <Hard granular layer>

[0084] The hard particle layer is composed of multiple hard particles comprising titanium (Ti), silicon (Si), carbon (C), and nitrogen (N). Examples of such hard particles include TiSiCN particles composed of titanium, silicon, carbon, and nitrogen. In addition to titanium, silicon, carbon, and nitrogen, the TiSiCN particles may contain unavoidable impurities, as long as they do not affect the effects of this disclosure. Unavoidable impurities include, for example, amorphous phases and intermetallic compounds (e.g., TiSi2, Co2Si, etc.), which do not depart from the scope of this disclosure as long as they contribute to the effects of this disclosure.

[0085] (Hard particles)

[0086] In the aforementioned hard particles, the silicon concentration varies periodically along a first direction defined within the hard particles. In this specification, the first direction is defined as the direction determined by the methods described below (A1) to (A4).

[0087] (A1) A diamond wire is used to cut along the normal of the rake face of the substrate using a cutting tool, exposing the cross-section of the hard granular layer. At this point, a thin section sample, processed using an ion slicer or similar equipment, is prepared as the test sample.

[0088] (A2) The processed thin-film sample was observed at 100,000x magnification using a bright-field scanning transmission electron microscope (BF-STEM) to identify a hard particle. Figure 5 This is a schematic diagram illustrating an example of a BF-STEM image (magnification: 100,000x) of the hard particle layer of this embodiment. Next, a BF-STEM image was obtained by observing a single hard particle at 2,000,000x magnification. Figure 6 It is a schematic representation Figure 5 An example of a BF-STEM image (observation magnification: 2 millionx) of a hard particle identified in the study.

[0089] (A3) In the above BF-STEM image (observation magnification: 2 million times), identify the region (hereinafter, also referred to as the "stacked region") where the black layer (hereinafter, also referred to as the "first unit layer") and the gray layer (hereinafter, also referred to as the "second unit layer") are stacked alternately and approximately parallel. The black first unit layer is the region with a high silicon content, and the gray second unit layer is the region with a low silicon content.

[0090] (A4) Within the aforementioned defined stacked region, determine the stacking orientation of the first unit layer (shown in black) and the second unit layer (shown in gray). Specifically, the electron diffraction pattern limiting the field of view is aligned with the stacking orientation of the first and second unit layers, and the orientation indicated by the diffraction spot is used to determine the stacking orientation. Figure 6 In the diagram, the stacking direction of the first and second unit layers is indicated by an arrow pointing from circle S to circle E. In this specification, this stacking direction is defined as the first direction.

[0091] As described above, in this specification, the first direction can also be defined as the direction along the stacking direction within the hard particles.

[0092] In the hard particle layer of this embodiment, the line along the first direction intersects the interface between the substrate and the coating at a predetermined angle of 45° or more and 90° or less.

[0093] In this specification, the situation in which the concentration of silicon in the hard particles changes periodically along a first direction set within the hard particles is confirmed by the following method.

[0094] (B1) In the above BF-STEM image (observation magnification: 2 millionx), line analysis was performed along the first direction using EDX (Energy Dispersive X-ray Spectroscopy) with an attached STEM to determine the atomic number basis of titanium content A. Ti And the content A based on the atomic number of silicon Si The measurements were performed. The beam diameter for line analysis was set to less than 0.5 nm, the scanning interval to 0.5 nm, and the line analysis length to 50 nm.

[0095] (B2) Obtain a graph showing the results of the line analysis on a coordinate system, in which the X-axis is set as the distance (nm) from the starting point of the line analysis along the first direction, and the Y-axis is set as the number of silicon atoms A. Si Relative to the number of atoms A of silicon Si With the number of atoms A of titanium Ti The total percentage ({A) Si / (A Si +A Ti ()}×100)(%). This chart represents the number of silicon atoms A as the distance (X-axis) along the first direction from the starting point of the line analysis increases. Si Relative to the number of atoms A of silicon Si With the number of atoms A of titanium Ti The total percentage change (Y-axis).

[0096] Figure 7 Indicates to Figure 6 An example of a graph obtained by line analysis of the arrows from circle S to circle E in a BF-STEM image.

[0097] (B3) Draw the diagram above to represent {A} Si / (A Si +A Ti The line L1 is the average of )}×100. Figure 7 In the middle, {A Si / (A Si +A Ti The average of 100 is e1. This average e1 is represented by line L1.

[0098] (B4) In the above chart, in {A Si / (A Si +A Ti The region whose value of )}×100 is greater than line L1 (hereinafter also referred to as "region 1A") and {A Si / (A Si +A Ti When a region whose value of )}×100 is smaller than line L1 (hereinafter also referred to as "region 1B") exists alternately and continuously along the first direction, it is determined that the concentration of silicon in the hard particle changes periodically along the first direction set within the hard particle. Here, {A Si / (A Si +A Ti The region that has the same average value as 100 is region 1A.

[0099] exist Figure 7 In this context, region 1A, for example, is the region along the first direction from the starting point of the line analysis where the distance is greater than or equal to c1 and less than c2, greater than or equal to c3 and less than c4, greater than or equal to c5 and less than c6, greater than or equal to c7 and less than c8, greater than or equal to c9 and less than c10, and greater than or equal to c11 and less than c12 (distances greater than c13 are omitted). Figure 7In the example, region 1B is the region along the first direction from the starting point of the line analysis that is more than c2 and less than c3, more than c4 and less than c5, more than c6 and less than c7, more than c8 and less than c9, more than c10 and less than c11, and more than c12 and less than c13.

[0100] Preferably, in each of the first A regions, as the distance from the starting point of the line analysis increases from the point closest to it, {A} Si / (A Si +A Ti The value of )}×100 increases from the average to the maximum value in the first A region, and then decreases back to the average.

[0101] The increase mentioned above in region 1A is not limited to monotonically increasing; it can also exist midway through the increase, with {A}. Si / (A Si +A Ti The decrease is within 50% of the difference between the average value of {A}×100 and the maximum value in region 1A. Furthermore, the decrease in region 1A is not limited to a monotonically decreasing trend; it can also occur midway through the decrease. Si / (A Si +A Ti The increase is within 50% of the difference between the average value of )}×100 and the maximum value in the first A region.

[0102] Preferably, in each of the 1B regions, as the distance from the starting point of the line analysis increases from the point closest to it, {A} Si / (A Si +A Ti The value of )}×100 decreases from the average to the minimum value in this 1B region, and then increases back to the average.

[0103] The decrease mentioned above in region 1B is not limited to monotonically decreasing; it can also exist midway through the decrease, with {A}. Si / (A Si +A Ti The increase is within 50% of the difference between the average value of )}×100 and the minimum value in region 1B. Furthermore, the increase in region 1B is not limited to monotonically increasing; it can also occur midway through the increase. Si / (A Si +A Ti The decrease of the average value of )}×100 within 50% of the difference between the minimum value in the 1B region.

[0104] For example, in Figure 7 In the first region A, located at a distance of c1 or more and c2 or less from the starting point of the line analysis along the first direction, {A} at point P1Si / (A Si +A Ti The value a1 of )}×100 is the maximum value within the first A region. Within this first A region, as the distance from the starting point of the line analysis along the first direction increases from c1 to c2, {A Si / (A Si +A Ti The value of )}×100 increases from the average value e1 to the maximum value a1, and then decreases from the maximum value a1 back to the average value e1. Figure 7 In the first region B, where the distance from the starting point of the line analysis along the first direction exceeds c2 but is less than c3, {A} at point B1... Si / (A Si +A Ti The value b1 of )}×100 is the minimum value within the first region B. Within this first region B, as the distance from the starting point of the line analysis along the first direction increases from c2 to c3, {A Si / (A Si +A Ti The value of )}×100 decreases from the average value e1 to the minimum value b1, and then increases from the minimum value b1 back to the average value e1.

[0105] By using the above method, as long as it is confirmed that the concentration of silicon in the hard particles changes periodically along a first direction set within the hard particles, the effects of this disclosure can be demonstrated.

[0106] ({A Si / (A Si +A Ti )}×100)

[0107] In the hard particles of this embodiment, the number of silicon atoms A Si Relative to the number of atoms A of titanium Ti With the number of atoms A of silicon Si The total percentage {A} Si / (A Si +A Ti The average of )}×100 is preferably 1% or more and 20% or less.

[0108] As a result, the wear resistance and chipping resistance of cutting tools are further improved, and the tool life is further extended.

[0109] From the perspective of improving membrane hardness and toughness, the above {A} Si / (A Si +A Ti The content of 1% to 10% is more preferably 1% to 10%, and even more preferably 1% to 5%.

[0110] In this specification, the above-mentioned {A} in hard particles Si / (A Si +A Ti The average of )}×100 refers to the area {A} in the hard particles that underwent line analysis. Si / (A Si +A Ti The average of the values ​​of )}×100.

[0111] From the perspective of improving membrane hardness and toughness, {A} in hard particles Si / (A Si +A Ti The maximum value of {A}×100 is preferably 1.5% or more and 40% or less, more preferably 1.5% or more and 20% or less, and even more preferably 1.5% or more and 10% or less. In this specification, "{A} in hard particles" Si / (A Si +A Ti The maximum value of {A}×100 is calculated using the following method. First, in each of the 1A regions present in the area where line analysis was performed in the hard particles, the value of {A} within that 1A region is calculated. Si / (A Si +A Ti The maximum value of {A}×100 was determined. The average of the maximum values ​​present in region 1A within the area where line analysis was performed corresponds to "{A} in hard particles". Si / (A Si +A Ti The maximum value of )}×100.

[0112] From the perspective of improving membrane hardness and toughness, {A} in hard particles Si / (A Si +A Ti The minimum value of {A}×100 is more preferably 0% or more and 1.0% or less, and even more preferably 0% or more and 0.5% or less. In this specification, "{A} in hard particles" Si / (A Si +A Ti The minimum value of {A}×100 is calculated using the following method. First, in each of the 1B regions present in the area where line analysis was performed in the hard particles, the value of {A} in each of the 1B regions is calculated. Si / (A Si +A Ti The minimum value of )}×100 was determined. The average of the minimum values ​​in region 1B, which existed in the region where line analysis was performed, corresponds to "{A in hard particles". Si / (A Si +A TiThe minimum value of )}×100.

[0113] From the perspective of improving membrane hardness and toughness, {A Si / (A Si +A Ti The difference between the maximum and minimum values ​​of )}×100 is preferably 1% or more and 38% or less, more preferably 1% or more and 20% or less, and even more preferably 1% or more and 8% or less.

[0114] It was confirmed that as long as the measurement was performed on the same sample, even if the measurement site for the linear analysis in the hard particles was changed and the measurement was performed multiple times, the measurement results were almost without deviation, and the results would not change arbitrarily even if the measurement site was set arbitrarily.

[0115] (Average period width of silicon concentration)

[0116] In the hard particles of this embodiment, the silicon concentration varies periodically along a first direction defined within the hard particles. The average period width of the silicon concentration along this first direction is preferably 3 nm or more and 50 nm or less. This improves wear resistance and chip resistance, and increases tool life. From the viewpoint of improving chip resistance, the lower limit of the period width of the silicon concentration is preferably 3 nm or more, more preferably 4 nm or more, and even more preferably 5 nm or more. From the viewpoint of improving wear resistance, the upper limit of the period width of the silicon concentration is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. The period width of the silicon concentration is more preferably 4 nm or more and 30 nm or less, and even more preferably 5 nm or more and 10 nm or less.

[0117] In this specification, the method for determining the period width of the silicon concentration is as follows. A stacked region is defined using the same method as described in (A1) to (A3). A Fourier transform is performed on the stacked region to obtain a Fourier transform image. In this Fourier transform image, the periodicity within the stacked region is represented by points. The period width is calculated by taking the reciprocal of the distance between these points and the center of the image representing the maximum intensity in the Fourier transform image.

[0118] It was confirmed that as long as the measurement is performed on the same sample, even if the measurement site is changed multiple times within the stacked area of ​​hard particles, the measurement results will have almost no deviation. Even if the measurement site is set arbitrarily, the results will not change arbitrarily.

[0119] The period width obtained by the Fourier transform described above corresponds to {A} existing in the adjacent 1A-th region. Si / (A Si +A Ti )}×100 is the distance along the first direction between the positions of the maximum value. {A} exists within the adjacent 1A region.Si / (A Si +A Ti The distance along the first direction between the positions where the maximum value is )}×100 is in Figure 7 The distances d1, d2, d3, d4, d5, d6 are equivalent to the distances between P1 and P2, P2 and P3, P3 and P4, P4 and P5, P5 and P6, and P6 and P7, respectively.

[0120] (Particle size of hard particles)

[0121] The particle size of the hard particles in this embodiment is preferably 10 nm or more and 1000 nm or less. This results in excellent resistance to chipping. More preferably, the particle size of the hard particles is 10 nm or more and 700 nm or less, and even more preferably 10 nm or more and 500 nm or less.

[0122] The method for determining the particle size is as follows. The substrate and the coating formed on the substrate are processed using FIB (fiber optic) to allow a cross-section to be seen. This cross-section is then observed using FE-SEM (field emission scanning electron microscopy). At this point, by observing the reflected electron image, portions with the same crystal orientation are observed at the same contrast, and these portions with the same contrast are considered as a single hard particle.

[0123] Next, for the image thus obtained, a straight line of arbitrary length (preferably equivalent to 400 μm) parallel to the substrate surface is drawn at any location in the hard particle layer. Then, the number of hard particles contained in the straight line is measured, and the value obtained by dividing the length of the straight line by the number of hard particles is taken as the particle size of the hard particles.

[0124] (Orientation of the hard particle layer)

[0125] In this embodiment, the orientation of the hard particle layer is (220) orientation. In this specification, "the orientation of the hard particle layer is (220) orientation" means that, in the orientation index TC(hkl) defined by the following formula (1), the orientation index TC(220) of the (220) facet in the hard particle layer is greater than the orientation index of other crystal orientation faces. Here, other crystal orientation faces refer to the (111) facet, (200) facet, (311) facet, (331) facet, (420) facet, (422) facet, and (511) facet.

[0126] [Number 1]

[0127]

[0128] In equation (1), I(hkl) and I(h x k yl z ) represent the measured diffraction intensity of the (hkl) plane and the measured (h) plane, respectively. x k y l z The diffraction intensity of the plane, I0(hkl) and I0(h) x k y l z The numbers represent the average powder diffraction intensities of TiC (card number: 32-1383) and TiN (card number: 38-1420) on the (hkl) plane based on the JCPDS (Joint Committee on Powder Diffraction Standards) database, respectively, and the values ​​based on the JCPDS database (hkl). x k y l z The average values ​​of the powder diffraction intensities of TiC and TiN on the surface, (hkl) and (h x k y l z ) represent any one of the eight faces: (111), (200), (220), (311), (331), (420), (422), and (511).

[0129] From the viewpoint of improving elastic recovery rate and, in particular, improving wear resistance in cast iron cutting, the orientation index TC(220) of the hard particle layer in this embodiment is preferably 3.5 or more, more preferably 5 or more, and even more preferably 6 or more. There is no upper limit to the value of the orientation index TC(220), but since eight reflective surfaces are used in the calculation, a value of 8 or less is acceptable. The value of the orientation index TC(220) is preferably 3.5 or more and 8 or less, more preferably 5 or more and 8 or less, and even more preferably 6 or more and 8 or less.

[0130] The orientation index TC(220) is determined by X-ray diffraction measurement under the following conditions. Specifically, X-ray diffraction measurement is performed at any point in the hard particle layer (device: SmartLab manufactured by Rigaku Co., Ltd. (registered trademark)), and the orientation index of the (220) plane calculated based on the above formula (1) is taken as the orientation index TC(220) in the hard particle layer. When selecting the above "any point", points that are obviously outliers are excluded.

[0131] Conditions for X-ray Diffraction Measurement

[0132] X-ray output: 45kV, 200mA

[0133] X-ray source, wavelength: CuKα

[0134] Detector: D / teX Ultra 250

[0135] Scan axis: 2θ / θ

[0136] Long side limit slit width: 2.0mm

[0137] Scan mode: CONTINUOUS (continuous)

[0138] Scanning speed: 20° / min

[0139] It was confirmed that as long as the measurement is performed on the same sample, even if the measurement site in the hard particle layer is changed and the measurement is performed multiple times, the measurement results will have almost no deviation. Even if the measurement site is set arbitrarily, the results will not change arbitrarily.

[0140] <Other Layers>

[0141] As mentioned above, the coating can include layers other than the rigid particle layer. For example... Figures 2-4 As shown, other layers include the base layer 12 and the outermost layer 13, etc.

[0142] (Basal layer)

[0143] A base layer is disposed between the substrate and the hard particle layer. Examples of base layers include TiN, TiC, TiCN, TiBN, and Al2O3 layers. By placing a TiN, TiC, TiCN, or TiBN layer directly above the substrate as a base layer, the adhesion between the substrate and the coating can be improved. Furthermore, using an Al2O3 layer as a base layer can improve the oxidation resistance of the coating. The average thickness of the base layer is preferably 0.1 μm or more and 20 μm or less. Therefore, the coating exhibits excellent wear resistance and damage resistance.

[0144] The basal layer can consist of a single layer. Additionally, as... Figure 4 As shown, the substrate 12 may have a two-layer structure consisting of a first substrate 12A disposed on the substrate side and a second substrate 12B disposed on the opposite side of the substrate. When the substrate has a two-layer structure, a combination of a TiN layer and a TiCN layer is preferred. Since the TiCN layer has excellent wear resistance, appropriate wear resistance can be imparted through coating. The average thickness of the first substrate layer is preferably 0.1 μm or more and 20 μm or less, more preferably 0.1 μm or more and 19 μm or less. The average thickness of the second substrate layer is preferably 1 μm or more and 20 μm or less, more preferably 1 μm or more and 19.9 μm or less.

[0145] (outermost layer)

[0146] The outermost layer is the layer disposed on the outermost surface of the coating. However, there are cases where the outermost layer is not formed at the blade edge. When no other layers are formed on the hard particle layer, the outermost layer is disposed directly above the hard particle layer. As the outermost layer, it is preferable to have any one of Ti (titanium) carbides, nitrides, and borides as the main component. In addition, using an Al2O3 layer as the outermost layer can improve the oxidation resistance of the coating.

[0147] "Main component of any one of Ti carbides, nitrides and borides" means containing 90% by mass or more of any one of Ti carbides, nitrides and borides. Furthermore, it preferably consists of any one of Ti carbides, nitrides and borides, excluding unavoidable impurities.

[0148] Of any of the carbides, nitrides, and borides of Ti, the outermost layer is particularly preferred to be composed primarily of Ti nitrides (i.e., compounds represented by TiN). TiN has the clearest color among these compounds (appearing golden), thus offering the advantage of easy identification of the corners of the cutting tool after use (identification of used areas). Preferably, the outermost layer is composed of a TiN layer.

[0149] The average thickness of the outermost layer is preferably 0.05 μm or more and 1 μm or less. This improves the adhesion between the outermost layer and the adjacent layers.

[0150] <Implementation Method 2: Method for Manufacturing Cutting Tools>

[0151] use Figure 8 An example of a method for manufacturing the cutting tool according to this embodiment will be described. Figure 8 This is a schematic cross-sectional view of an example of a CVD apparatus used in the manufacture of the cutting tool in this embodiment.

[0152] (Preparation of substrate)

[0153] Prepare the substrate. Details regarding the substrate have been described above and will not be repeated here.

[0154] (Formation of the coating)

[0155] Next, using, for example Figure 8 The CVD apparatus shown forms a coating on the aforementioned substrate. Within the CVD apparatus 50, multiple substrate mounting fixtures 52 for holding the substrate 10 are provided, and these fixtures are covered by a reaction vessel 53 made of heat-resistant alloy steel. Furthermore, a temperature control device 54 is arranged around the reaction vessel 53, allowing for temperature control within the reaction vessel 53.

[0156] The CVD apparatus 50 is equipped with an inlet pipe 56 having two inlet ports 55 and 57. The inlet pipe 56 is configured to pass through the area where the substrate mounting fixture 52 is mounted, and multiple through holes are formed in the portion near the substrate mounting fixture 52. In the inlet pipe 56, the gases introduced into the pipe from the inlet ports 55 and 57 do not mix within the pipe 56, but are instead introduced into the reaction vessel 53 separately through different through holes. The inlet pipe 56 is rotatable around its axis. Additionally, the CVD apparatus 50 is equipped with an exhaust pipe 59, from which exhaust gases can be discharged to the outside through the exhaust port 60. Furthermore, the fixtures and the like within the reaction vessel 53 are typically made of graphite.

[0157] In cases where the coating comprises a base layer and / or an outermost layer, these layers can be formed using methods known in the past.

[0158] The hard particulate layer can be formed using the CVD apparatus described above by the following method. Specifically, a first feed gas containing Ti and Si is introduced into the inlet tube 56 through inlet 55, and a second feed gas containing C and N is introduced into the inlet tube 56 through inlet 57. The first feed gas may, for example, contain TiCl4 gas and SiCl4 gas. The second feed gas may, for example, contain CH3CN gas. Furthermore, the first and second feed gases may each contain a carrier gas (H2 gas, N2 gas, or Ar gas, etc.). Hereinafter, the total amount of the first and second feed gases in the reaction vessel will be referred to as the reaction gas.

[0159] Multiple through holes are provided on the upper side of the inlet pipe 56. The first raw material gas (or the first mixed gas composed of the first raw material gas and the carrier gas) and the second raw material gas (or the second mixed gas composed of the second raw material gas and the carrier gas) are injected into the reaction vessel 53 through different through holes. At this time, as shown by the rotating arrow in the figure, the inlet pipe 56 rotates around its axis. Therefore, the first raw material gas (or the first mixed gas) and the second raw material gas (or the second mixed gas) are sprayed onto the surface of the substrate 10, which is provided on the substrate mounting fixture 52, as a uniformly mixed gas.

[0160] In the formation of the hard particulate layer, the total gas flow rate of the reaction gas can be set to, for example, 10 to 80 L / min. Here, "total gas flow rate" means the total volumetric flow rate introduced into the CVD furnace per unit time, taking the gas under standard conditions (0°C, 1 atmosphere) as an ideal gas.

[0161] During the formation of the hard granular layer, the ratio of TiCl4 gas to CH3CN gas in the reaction gas remains constant. The proportion of TiCl4 gas in the reaction gas can be set, for example, to 0.35–1.30% by volume. The proportion of CH3CN gas in the reaction gas can be set, for example, to 0.5–0.7% by volume.

[0162] By adjusting the amount of SiCl4 gas introduced, the proportion of SiCl4 gas in the reaction gas is periodically varied. Specifically, with the length of one cycle of the SiCl4 gas introduction rate set to t (seconds) and the range of the SiCl4 gas proportion in the reaction gas set to r1 (volume%) to r2 (volume%), the amount of SiCl4 gas introduced is adjusted so that from the start of film formation to the midpoint of one cycle (t / 2 (seconds)), the proportion of SiCl4 gas gradually increases from r1 (volume%) to r2 (volume%), and then from the midpoint (t / 2 (seconds)) to the final moment of one cycle (t (seconds)), the proportion of SiCl4 gas gradually decreases from r2 (volume%) to r1 (volume%). This is considered one cycle, and the cycle is repeated until the hard particle layer reaches the desired thickness. The proportion of the carrier gas (e.g., H2 gas) in the reaction gas is varied in a manner that keeps the total gas flow rate constant, based on the change in the SiCl4 gas proportion. By adjusting the length t (seconds) of one cycle, the cycle width (nm) of silicon concentration in the hard particles can be controlled. By adjusting the minimum value r1 and maximum value r2 of the proportion of SiCl4 gas in the reaction gas, the concentration of A in the hard particles can be controlled. Si / (A Si +A Ti The value of ) is controlled.

[0163] In this process, the temperature of the substrate 10 is preferably in the range of 900–950°C, and the pressure inside the reaction vessel 53 is preferably 0.1–13.0 kPa. By setting the substrate temperature during film formation to the above range, the orientation of the hard particle layer becomes (220) orientation. The substrate temperature during film formation is higher than the substrate temperature used in the conventional TiSiCN layer formation process (e.g., 800–850°C). The thickness of the hard particle layer can be controlled by adjusting the flow rate of the raw material gas and the film formation time.

[0164] Next, the substrate 10 with the coating is cooled. The cooling rate is, for example, no more than 5°C / min, and the cooling rate slows down as the temperature of the substrate 10 decreases.

[0165] In addition to the above-mentioned processes, heat treatment processes such as annealing, surface grinding, and shot peening can also be performed.

[0166] The cutting tool of Embodiment 1 can be obtained by the manufacturing method described above.

[0167] [Postscript 1]

[0168] In the cutting tool disclosed herein, the orientation index TC(220) of the hard particle layer is preferably 3.5 or more and 8 or less, more preferably 5 or more and 8 or less, and even more preferably 6 or more and 8 or less.

[0169] Example

[0170] This embodiment will be described in more detail through examples. However, this embodiment is not limited to these examples.

[0171] <Preparation of Substrate>

[0172] Prepare the substrates K, L, and M listed in Table 1 below. Specifically, first, uniformly mix the raw material powders consisting of the proportions (mass%) listed in Table 1 to obtain a mixed powder. "Balance" in Table 1 indicates the remaining portion of WC in the proportions (mass%). Next, press the mixed powder into the shape of CNMG120408 (an indexable cutting insert manufactured by Sumitomo Electric Industries, Ltd.), and sinter it at 1300–1500°C for 1–2 hours to obtain cemented carbide substrates K, L, and M. The substrate shape of substrates K, L, and M is CNMG120408.

[0173] Table 1

[0174]

[0175] <Formation of the coating>

[0176] For the substrate K, substrate L, or substrate M obtained above, a coating is formed on its surface. Specifically, using Figure 8 The CVD apparatus shown depicts a substrate placed in a substrate fixture, where a thermal CVD method is performed to form a coating on the substrate. The composition of the coatings for each sample is shown in Table 2.

[0177] Table Z

[0178]

[0179] In Table 2, the base layer is the layer in direct contact with the surface of the substrate, the hard particle layer is the layer formed directly above the base layer, and the outermost layer is the layer formed directly above the hard particle layer and exposed to the outside. Furthermore, the compounds listed in the base layer and outermost layer columns of Table 2 are the compounds constituting the base layer and outermost layer of Table 2, respectively. The values ​​in parentheses to the right of the compound indicate the layer thickness. Additionally, if two compounds are listed in one column of Table 2 (e.g., "TiN(0.5)-TiCN(3.0)"), it means that the compound on the left ("TiN(0.5)") constitutes the layer located closer to the substrate, and the compound on the right ("TiCN(3.0)") constitutes the layer located farther from the substrate. The values ​​in parentheses indicate the thickness of each layer. The a-p and w-z listings for the hard particle layers in Table 2 represent layers formed under the formation conditions a-p and w-z of Table 4. The values ​​in parentheses indicate the layer thickness. Additionally, the column marked with "-" in Table 2 indicates that the layer does not exist.

[0180] For example, in the cutting tool of sample 1 in Table 2, a base layer is formed by sequentially stacking a TiN layer with a thickness of 0.5 μm and a TiCN layer with a thickness of 3.0 μm directly above the surface of the substrate K. A hard particle layer with a thickness of 5.1 μm is formed directly above this base layer under formation condition a described later, and the overall thickness of the coating is 8.6 μm. In sample 1, no outermost layer is formed directly above the hard particle layer.

[0181] The base layer and outermost layer shown in Table 2 are formed using conventional CVD methods, and their formation conditions are shown in Table 3. For example, the formation conditions of the TiN layer as the base layer are shown in the "TiN (Base Layer)" row of Table 3. The TiN (Base Layer) described in Table 3 refers to the formation of the layer by placing a substrate in the reaction vessel of a CVD apparatus (pressure 6.7 kPa), heating the substrate to a temperature of 915°C, and injecting a mixture of 2.0 vol% TiCl4 gas, 39.7 vol% N2 gas, and the balance (58.3 vol%) H2 gas into the reaction vessel at a flow rate of 63.8 L / min. Furthermore, the thickness of each layer is controlled by the injection time of each reaction gas.

[0182] Table 3

[0183]

[0184] The hard granular layer shown in Table 2 is formed under any of the formation conditions a to p and w to z shown in Table 4.

[0185] (Formation conditions a to p and z)

[0186] In formation conditions a to p and z, firstly, the pressure inside the reaction vessel of the CVD apparatus is set to the pressure listed in the "Pressure inside the reaction vessel (kPa)" column of Table 4, and the substrate temperature is set to the temperature listed in the "Substrate temperature (°C)" column of Table 4. For example, under formation condition a, the pressure inside the reaction vessel of the CVD apparatus is set to 9.0 kPa, and the substrate temperature is set to 920°C.

[0187] Next, a reaction gas containing the components listed in the "Reaction Gas Composition" column of Table 4 is introduced into the reaction vessel to form a hard particulate layer (TiSiCN layer) on the substrate. The total gas flow rate of the reaction gas is as shown in the "Total Gas Flow Rate (L / min)" column of Table 4. "Total Gas Flow Rate" represents the total volumetric flow rate introduced into the CVD furnace per unit time, taking the gas under standard conditions (0°C, 1 atmosphere) as an ideal gas.

[0188] The proportions of TiCl4, CH3CN, and N2 gases in the reaction gases remained constant throughout the formation of the hard particle layer. The proportion of SiCl4 gas in the reaction gases varied within the range (volume %) shown in the "Range" column, with each cycle defined as the time (seconds) in the "Cycle" column of Table 4. Specifically, the amount of SiCl4 gas introduced was adjusted as follows: the proportion of SiCl4 gas at the start of film formation was set to the minimum value shown in the "Range" column. From the start of film formation until the midpoint of the time (seconds) shown in the "Cycle" column of Table 4 ((1 / 2) cycle (seconds)), the proportion of SiCl4 gas gradually increased to the maximum value shown in the "Range" column. Then, from the midpoint ((1 / 2) cycle (seconds)) to the final moment of a cycle (one cycle (seconds)), the proportion of SiCl4 gas gradually decreased to the minimum value shown in the "Range" column. This was repeated as one cycle until the hard particle layer reached the desired thickness. The proportion of H2 gas varies with the proportion of SiCl4 gas while keeping the total gas flow rate constant.

[0189] For example, under formation condition a, the total gas flow rate of the reactants is 60.0 L / min. The proportions of TiCl4 gas, CH3CN gas, and N2 gas in the reactants are 0.70 vol%, 0.60 vol%, and 8.90 vol%, respectively, and these proportions remain constant during the formation of the hard particle layer. The proportion of SiCl4 gas in the reactants varies from 0.1 to 1.7 vol% in a 7-second cycle. More specifically, the amount of SiCl4 gas introduced is adjusted as follows: the proportion of SiCl4 gas at the start of film formation is set to 0.1 vol%, and from the start of film formation until 3.5 seconds later, the proportion of SiCl4 gas gradually increases from 0.1 vol% to 1.7 vol%. Then, from 3.5 seconds later until 7 seconds later, the proportion of SiCl4 gas gradually decreases from 1.7 vol% to 0.1 vol%. This is repeated as one cycle until the thickness of the hard particle layer reaches the thickness listed in the "Hard Particle Layer" column of Table 2. The volume percentage of H2 gas varies with the proportion of SiCl4 gas while keeping the total gas flow rate constant. Under formation condition a, the average proportion of SiCl4 gas in the reaction gases is 0.90% by volume.

[0190] The substrate was then cooled at a rate of 5°C / minute.

[0191] (Condition w)

[0192] The formation conditions w are the same as those for the conventional TiCN layer formation. Specifically, firstly, the pressure inside the reaction vessel of the CVD apparatus is set to 9.0 kPa, and the substrate temperature is set to 920°C.

[0193] Next, a reaction gas containing the components listed in the "Reaction Gas Composition (volume %)" column of Table 4 (TiCl4: 2.00 vol%, CH3CN: 0.60 vol%, H2 gas: balance) was introduced into the reaction vessel to form a TiCN layer (hard particle layer) on the substrate. The composition of the reaction gas remained constant during film formation. The total gas flow rate of the reaction gas was 60.0 L / min. The substrate was then cooled at a rate of 5 °C / min.

[0194] (Condition x)

[0195] The formation condition x is the condition for forming a hard particulate layer (TiSiCN layer) using the PVD method disclosed in Patent Document 1.

[0196] (Condition y)

[0197] The formation condition y is the condition for forming a hard particulate layer (TiSiCN layer) using the CVD method disclosed in Patent Document 2.

[0198] Based on the above, cutting tools for specimens 1 to 27 (equivalent to examples) and specimens 1-1 to 1-5 (equivalent to comparative examples) were obtained.

[0199] Table 4

[0200]

[0201] <Characteristics of Hard Granular Layers>

[0202] (Composition of the hard granular layer)

[0203] It was confirmed that the hard particle layer obtained by forming conditions a to p and forming condition z consists of multiple hard particles made of TiSiCN, and the silicon concentration varies periodically along a first direction set within the hard particles. The specific confirmation method is described in Embodiment 1, and therefore will not be repeated.

[0204] The hard granular (TiCN) layer obtained by forming condition w was observed using bright field scanning transmission electron microscopy (BF-STEM). The results showed that the tissue was homogeneous and no periodic changes were identified.

[0205] The hard particle layer obtained under formation conditions x and y was observed using bright-field scanning transmission electron microscopy (BF-STEM), and the nanocomposite structure was confirmed. The hard particle layer was (200) oriented.

[0206] ({A Si / (A Si +A Ti )}×100)

[0207] Among the hard particles obtained under various formation conditions, for {A Si / (A Si +A Ti The maximum, minimum, and average values ​​of {A} × 100 were measured. The specific measurement method is as described in Implementation Method 1, and therefore will not be repeated. The results are shown in Table 5 under “Maximum {A}”. Si / (A Si +A Ti )}×100(%)", "Min{A Si / (A Si +A Ti ")}×100(%)" and "Average {A Si / (A Si +A Ti In the column “)}×100(%)”, the “-” mark indicates that no measurement was performed.

[0208] (Period width of silicon concentration)

[0209] In the hard particles obtained under various formation conditions, the average period width of the silicon concentration in a first direction set within the hard particles was measured. The specific measurement method is as described in Embodiment 1, and therefore will not be repeated. The results are shown in the "Average Period Width (nm)" column of Table 5. In addition, the "-" mark indicates that no measurement was performed.

[0210] (orientation)

[0211] The orientation of the hard particle layers obtained under each formation condition was measured. The specific method for measuring the orientation of the hard particle layers is described in Embodiment 1, and therefore will not be repeated. In each hard particle layer, the orientation face with the largest orientation index TC(hkl) is shown in the "Orientation Face" column of Table 5, and the orientation index TC(hkl) of that orientation face is shown in the "Orientation Index TC(hkl) of Orientation Face" column.

[0212] Among the hard particle layers obtained by forming conditions a to p and forming condition w, the orientation index TC(220) of the (220) plane is the largest. Therefore, the orientation of the hard particle layers obtained by forming conditions a to p and forming condition w is the (220) orientation. For example, the orientation index TC(220) of the hard particle layer obtained by forming condition a is 4.3.

[0213] In the hard particle layer obtained by forming conditions x to z, the orientation index TC(200) of the (200) plane is the largest. Therefore, the orientation of the hard particle layer obtained by forming conditions x to z is the (200) orientation.

[0214] Table 5

[0215]

[0216] <Cutting Experiment 1>

[0217] Using cutting tools from specimens 1 to 27 and specimens 1-1 to 1-5, continuous cutting of cast iron (FCD450) was performed under the following cutting conditions, and the cutting time until the flank wear (Vb) reached 0.3 mm was measured. A longer cutting time indicates better wear resistance and a longer tool life. Furthermore, the final damage morphology of the tool tip was observed. In the final damage morphology, "normal wear" refers to a damage morphology consisting only of wear without chipping, defects, etc. (having a smooth wear surface), indicating excellent resistance to defects. The results are shown in Table 6.

[0218] <Cutting Conditions>

[0219] Workpiece to be machined: External circumference cutting of FCD450 round bar

[0220] Circular speed: 150m / min

[0221] Feed rate: 0.15 mm / rev

[0222] Cut depth: 1.0mm

[0223] Cutting fluid: None

[0224] Table 6

[0225]

[0226] (Evaluation 1)

[0227] It was confirmed that samples 1 to 27 (Examples) exhibited superior wear resistance and longer tool life during continuous cutting of cast iron compared to samples 1-1 to 1-5 (Comparative Examples). Furthermore, it was confirmed that the final wear mode of samples 1 to 27 was normal wear, maintaining the same excellent resistance to chipping as the conventional hard granular layers (samples 1-1 to 1-5).

[0228] <Cutting Experiment 2>

[0229] Using cutting tools from specimens 1 to 27 and specimens 1-1 to 1-5, intermittent cutting of cast iron (FC250) was performed under the following cutting conditions. The number of impacts until the cutting tool broke was measured to evaluate the tool's resistance to chipping. Here, chipping refers to defects larger than 300 μm. The more impacts until chipping, the better the resistance to chipping. The results are shown in Table 7. Furthermore, in Table 7, "no chipping" indicates that cutting was performed up to 3000 impacts without chipping.

[0230] <Cutting Conditions>

[0231] Workpiece to be cut: FC250 sheet metal outer periphery cutting

[0232] Circular speed: 300m / min

[0233] Feed rate: 0.2 mm / rev

[0234] Cut depth: 1.5mm

[0235] Cutting fluid: None

[0236] Table 7

[0237]

[0238] (Evaluation 2)

[0239] It was confirmed that samples 1-27 (Examples) exhibited superior resistance to chipping and longer tool life in intermittent cutting of cast iron compared to samples 1-1 to 1-5 (Comparative Examples).

[0240] The embodiments and examples of this disclosure have been described above, but it is also intended from the outset that the above-described embodiments and examples may be appropriately combined or modified.

[0241] The embodiments and examples disclosed herein should be considered exemplary in all respects, and not restrictive. The scope of the invention is defined not by the foregoing embodiments and examples, but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0242] Explanation of reference numerals in the attached figures

[0243] 1, 21, 31, 41: Cutting tools; 10: Substrate; 11: Hard particle layer; 12, 12A, 12B: Base layer; 13: Outermost layer; 14, 24, 34, 45: Coating; 50: CVD device; 52: Substrate mounting fixture; 53: Reaction vessel; 54: Temperature control device; 55, 57: Inlet; 56: Inlet pipe; 59: Exhaust pipe; 60: Exhaust port.

Claims

1. A cutting tool comprising a substrate and a coating film provided on the substrate, wherein the coating film comprises a hard particle layer, the hard particle layer is composed of a plurality of hard particles comprising titanium, silicon, carbon, and nitrogen, in the hard particles, a concentration of the silicon periodically changes along a first direction set within the hard particles, an orientation of the hard particle layer is (220) orientation, the first direction is a direction along a stacking direction of a first unit layer and a second unit layer within the hard particles, the first unit layer is a region in which a content of silicon is high, and the second unit layer is a region in which a content of silicon is low, the orientation of the hard particle layer being (220) orientation means that, in an orientation index TC(hkl) defined by the following formula (1), an orientation index TC(220) of a (220) plane in the hard particle layer is larger than orientation indices of a (111) plane, a (200) plane, a (311) plane, a (331) plane, a (420) plane, a (422) plane, and a (511) plane, In the formula (1), I(hkl) and I(h x k y l z ) represent the measured diffraction intensity of the (hkl) plane and the measured diffraction intensity of the (h x k y l z ) plane, respectively, I0(hkl) and I0(h x k y l z ) represent the average of the powder diffraction intensity of TiC (card number: 32-1383) and TiN (card number: 38-1420) of the (hkl) plane based on the JCPDS (Joint Committee on Powder Diffraction Standards) database and the average of the powder diffraction intensity of TiC and TiN of the (h x k y l z ) plane based on the JCPDS database, respectively, and (hkl) and (h x k y l z ) represent any one of the (111) plane, the (200) plane, the (220) plane, the (311) plane, the (331) plane, the (420) plane, the (422) plane, and the (511) plane.

2. The cutting tool of claim 1, wherein, In the hard particles, the atomic number A of the silicon Si The atomic number A of the titanium Ti The atomic number A of the silicon Si The atomic number A of the titanium Si The atomic number A of the silicon Si The atomic number A of the titanium Ti is 1% or more and 20% or less.

3. The cutting tool of claim 2, wherein, The {A Si / (A Si +A Ti ) x 100 is 1% or more and 10% or less on average.

4. The cutting tool according to any one of claims 1 to 3, wherein, an average period width of the concentration of the silicon is 3 nm or more and 50 nm or less.

5. The cutting tool according to any one of claims 1 to 3, wherein, an average period width of the concentration of the silicon is 4 nm or more and 30 nm or less.

6. The cutting tool of any one of claims 1 to 3, wherein, a thickness of the hard particle layer is 1 μm or more and 20 μm or less.

7. The cutting tool according to any one of claims 1 to 3, wherein, the substrate is composed of a cemented carbide comprising tungsten carbide and cobalt, a content of the cobalt in the cemented carbide is 6 mass% or more and 11 mass% or less.

8. The cutting tool according to any one of claims 1 to 3, wherein, In the hard particles, the atomic number A of the silicon Si The atomic number A of the titanium Ti The atomic number A of the silicon Si The atomic number A of the titanium Si The atomic number A of the silicon Si The atomic number A of the titanium Ti The difference between the maximum value and the minimum value of the percentage {A / (A+A+A)}x100 of the sum of the atomic number A of the silicon 9. The cutting tool of any one of claims 1 to 3, wherein, a value of the orientation index TC(220) of the hard particle layer is 3.5 or more and 8 or less.

10. The cutting tool according to any one of claims 1 to 3, wherein the coating film comprises a base layer provided directly above the substrate, the base layer is composed of at least one selected from the group consisting of a TiN layer, a TiC layer, a TiCN layer, a TiBN layer, and an Al2O3 layer.

11. The cutting tool according to any one of claims 1 to 3, wherein the coating film comprises an outermost layer provided at a most surface side in the coating film, the outermost layer is composed of a layer comprising a carbide of titanium, a nitride of titanium, or a boride of titanium at 90 mass% or more, or an Al2O3 layer.

12. The cutting tool according to any one of claims 1 to 3, wherein a thickness of the coating film is 1 μm or more and 30 μm or less.

13. The cutting tool according to any one of claims 1 to 3, wherein In the hard particles, the atomic number A of the silicon Si The atomic number A of the titanium Ti The atomic number A of the silicon Si The atomic number A of the titanium Si The atomic number A of the silicon Si The atomic number A of the titanium Ti The maximum value of the percentage {A / (A + A)} x 100 of the sum of the atomic number A of the silicon and the atomic number A of the titanium is 1.5% or more and 40% or less.

14. The cutting tool according to any one of claims 1 to 3, wherein In the hard particles, the atomic number A of the silicon Si The atomic number A of the titanium Ti The atomic number A of the silicon Si The atomic number A of the titanium Si The atomic number A of the silicon Si The atomic number A of the titanium Ti The minimum value of the percentage {A / (A + A)} x 100 of the sum of the atomic number A of the silicon and the atomic number A of the titanium is 0% or more and 1.0% or less.

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