Cutting tool
By forming a specially designed α-Al2O3 coating on the cutting tool, the problems of insufficient wear resistance and chipping resistance in turning are solved, and the tool life is significantly improved.
Patent Information
- Application Number
- CN202480049832.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-08
- Publication Date
- 2026-03-03
AI Technical Summary
Existing cutting tools struggle to combine excellent wear resistance and chipping resistance in turning operations, resulting in insufficient tool life.
An α-Al2O3 coating with a thickness of more than 2 μm and less than 15 μm is formed on the substrate of the cutting tool. The grain boundaries of the coating are designed with specific cross angles and bend point distributions to ensure that the grain boundary ratio and surface roughness are within a specific range, so as to improve wear resistance and crack resistance.
It improves the tool life of cutting tools in turning, especially in suppressing grain coarsening and thermal crack propagation.
Smart Images
Figure CN121605016A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to cutting tools. Background Technology
[0002] Conventionally, cutting tools have a substrate and a coating disposed on the substrate, the coating comprising a first layer composed of α-Al2O3, and the cutting tool is used for cutting operations (Patent Document 1, Non-Patent Document 1).
[0003] Existing technical documents Patent documents Patent document 1: International Publication No. 2015 / 113866.
[0004] Non-patent literature Non-patent literature 1: S. Ruppi et al., “Influence of Process Conditions on the Growth and Texture of CVD Alpha-Alumina” Coatings 2020, 10, 158. Summary of the Invention
[0005] The cutting tool disclosed herein includes a substrate and a coating disposed on the substrate, wherein, The coating consists of a first layer. The first layer is composed of α-Al₂O₃. The thickness of the first layer is greater than 2 μm and less than 15 μm. In a cross-section along the normal to the interface between the substrate and the coating, the first layer includes a plurality of grain boundaries connecting the interface of the first layer near the substrate to the surface of the first layer or the interface of the first layer near the surface of the coating, wherein at least one grain boundary, i.e., the first grain boundary, has a plurality of straight portions and three or more bends connecting two adjacent straight portions. In this first grain boundary, the intersection angle A1 at the nearest bend point to the interface of the first layer near the substrate and the second nearest intersection angle A2 are both greater than 90° and less than 150°. In the first grain boundary, the intersection angle A4 at the nearest bend point to the interface of the first layer or the interface of the first layer near the coating film, and the second nearest intersection angle A3, are both greater than 120° and less than 180°. In this first grain boundary, the average X1 of the crossing angles A1 and A2 and the average X2 of the crossing angles A3 and A4 satisfy the relationship of Equation 1. The ratio N2 of the number of first grain boundaries to the number of grain boundaries N1, N2 / N1, is greater than 0.2. X2-X1≥10° Equation 1. Attached Figure Description
[0006] Figure 1 This is a schematic cross-sectional view illustrating one manner of the cutting tool of this disclosure.
[0007] Figure 2 yes Figure 1 Enlarged view in region II.
[0008] Figure 3 This is a schematic cross-sectional view of an example of a CVD (Chemical Vapor Deposition) apparatus used to manufacture the cutting tools disclosed herein. Detailed Implementation
[0009] [The problem this disclosure aims to solve] In recent years, the demand for improved tool life has been increasing, especially in turning operations, where further improvements in tool life are required. Key factors for improving tool life in turning operations include "wear resistance" and "chipping resistance." Furthermore, from the perspective of improving "chipping resistance," cutting tools are used that have a substrate and a coating disposed on the substrate. The coating includes a first layer composed of α-Al₂O₃ with a thickness of 2 μm or more and 15 μm or less. In a cross-section along the normal to the interface between the substrate and the coating, the first layer contains multiple grain boundaries connecting the interface of the first layer near the substrate to the surface of the first layer or the interface of the first layer near the surface of the coating. At least one of these grain boundaries, the first grain boundary, has multiple straight portions and three or more bends connecting two adjacent straight portions. However, in such cutting tools, due to the coarsening of particles in the region near the surface of the coating of the first layer, it is sometimes difficult to impart excellent "wear resistance." Therefore, it is required to endow cutting tools with excellent "wear resistance" and excellent "fracture resistance" to achieve superior tool life.
[0010] Therefore, the purpose of this disclosure is to provide a cutting tool that has excellent tool life, especially in turning operations.
[0011] [The Effects of This Disclosure] According to this disclosure, it is possible to provide cutting tools that have excellent tool life, especially in turning operations.
[0012] [Description of embodiments of this disclosure] First, embodiments of this disclosure will be described.
[0013] (1) The cutting tool of this disclosure comprises a substrate and a coating disposed on the substrate, wherein, The coating comprises a first layer. The first layer is composed of α-Al₂O₃. The thickness of the first layer is greater than 2 μm and less than 15 μm. In a cross-section along the normal to the interface between the substrate and the coating, the first layer includes a plurality of grain boundaries connecting the interface of the first layer near the substrate to the surface of the first layer or the interface of the first layer near the surface of the coating, wherein at least one grain boundary, i.e., the first grain boundary, has a plurality of straight portions and three or more bends connecting two adjacent straight portions. In the first grain boundary, the cross angle A1 at the nearest bend point to the interface of the first layer near the substrate and the second nearest cross angle A2 are both greater than 90° and less than 150°. In the first grain boundary, the intersection angle A4 at the nearest bend point to the surface of the first layer or the interface of the first layer near the surface of the coating, and the second nearest intersection angle A3, are both greater than 120° and less than 180°. In the first grain boundary, the average X1 of the crossing angles A1 and A2 and the average X2 of the crossing angles A3 and A4 satisfy the relationship of Equation 1. The ratio N2 / N1, representing the number of the first grain boundaries N2 relative to the number of grain boundaries N1, is 0.2 or more. X2-X1≥10° Equation 1.
[0014] According to this disclosure, it is possible to provide cutting tools that have excellent tool life, especially in turning operations.
[0015] (2) Alternatively, in (1) above, the average distance D1 between two adjacent bending points along the normal of the interface between the substrate and the coating at the first grain boundary is 0.05 μm or more and 4 μm or less. This provides a cutting tool with superior tool life, especially in turning operations.
[0016] (3) Alternatively, in (1) or (2) above, the thickness of the first layer is less than 8 μm, and the surface roughness Ra of the surface of the first layer, or the interface of the first layer located near the surface of the coating, is 0.03 μm or more and 0.2 μm or less. This provides a cutting tool with superior tool life, especially in turning operations.
[0017] (4) Alternatively, in (1) or (2) above, the thickness of the first layer is 8 μm or more. In the surface of the first layer, or in the interface of the first layer located near the surface of the coating, the surface roughness Ra is 0.05 μm or more and 0.2 μm or less. This allows for the provision of cutting tools with superior tool life, particularly in turning operations.
[0018] (5) Alternatively, in any of (1) to (4) above, the orientation index TC (0 012) of the first layer is greater than 4.5. Thus, it is possible to provide a cutting tool with superior tool life, especially in turning.
[0019] [Details of the embodiments disclosed herein] Hereinafter, with reference to the accompanying drawings, a specific example of a cutting tool according to one embodiment of the present disclosure (hereinafter also referred to as "this embodiment") will be described. 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.
[0020] In this disclosure, expressions in the form of "A~B" refer to the upper and lower limits of a range (i.e., above A and below B). When there is no unit recorded in A but only in B, the unit of A is the same as the unit of B.
[0021] In this disclosure, when compounds are represented by chemical formulas, all previously known atomic ratios are included without specifically limiting the atomic ratios, and are not necessarily limited to atomic ratios within the stoichiometric range.
[0022] [Implementation Method 1: Cutting Tool] use Figure 1 as well as Figure 2 The cutting tool involved in one embodiment of the present disclosure will be described. Figure 1 This is a schematic cross-sectional view illustrating one manner of the cutting tool of this disclosure. Figure 2 yes Figure 1 An enlarged view of region II.
[0023] One embodiment of this disclosure (hereinafter also referred to as "this embodiment") is a cutting tool 10 comprising a substrate 1 and a coating 2 disposed on the substrate 1, wherein, The coating 2 comprises a first layer 3. The first layer 3 is composed of α-Al2O3. The thickness of the first layer 3 is greater than 2μm and less than 15μm. In a cross-section along the normal to the interface between the substrate 1 and the coating 2, the first layer 3 includes a plurality of grain boundaries GB connecting the interface I1 of the first layer 3 near the substrate 1 to the surface S1 of the first layer 3 or the interface of the first layer 3 near the surface of the coating 2. At least one of the grain boundaries GB, namely the first grain boundary GB1, has a plurality of straight portions and three or more bends connecting two adjacent straight portions. In the first grain boundary GB1, the intersection angle A1 at the nearest bend point to the interface I1 of the first layer 3 near the substrate 1 and the second nearest intersection angle A2 are both 90° and less than 150°. In the first grain boundary GB1, the intersection angle A4 and the second nearest intersection angle A3 at the bend point closest to the surface S1 of the first layer 3 or the interface of the first layer 3 near the surface of the coating 2 are both greater than 120° and less than 180°. In the first grain boundary GB1, the average X1 of the cross angles A1 and A2 and the average X2 of the cross angles A3 and A4 satisfy the relationship of Equation 1. The ratio N2 of the number of first grain boundaries GB1 to the number of grain boundaries GB is greater than 0.2. X2-X1≥10° Equation 1.
[0024] According to this disclosure, a cutting tool 10 can be provided that has excellent tool life, especially in turning operations. The reason for this is speculated as follows.
[0025] In the cutting tool 10 of this embodiment, in a cross-section along the normal of the interface between the substrate 1 and the coating 2, the first layer 3 includes a plurality of grain boundaries GB connecting the interface I1 of the first layer 3 near the substrate 1 and the surface S1 of the first layer 3 or the interface of the first layer 3 near the surface of the coating 2. At least one grain boundary GB, namely the first grain boundary GB1, has a plurality of straight portions and three or more bending points connecting two adjacent straight portions. In the first grain boundary GB1, the intersection angle A1 at the bending point closest to the interface I1 of the first layer 3 near the substrate 1 and the second closest intersection angle A 2 are respectively 90° or more and 150° or less. In this first grain boundary GB1, the intersection angle A4 and the second nearest intersection angle A3 at the interface of the first layer 3 near the surface S1 or the surface of the first layer 3 near the coating 2 are respectively 120° or more and less than 180°. In this first grain boundary GB1, the average X1 of the intersection angles A1 and A2 and the average X2 of the intersection angles A3 and A4 satisfy the relationship of Equation 1 above. The ratio N2 of the number of first grain boundaries GB1 to the number of grain boundaries GB N1, N2 / N1, is 0.2 or more. Therefore, in the first layer 3, since the coarsening of particles is easily suppressed, especially during turning, the shedding of particles is easily suppressed, resulting in improved wear resistance of the first layer 3. In addition, in the region of the first layer 3 near the substrate 1, thermal crack propagation is easily suppressed, resulting in improved chipping resistance of the first layer 3. Therefore, in the first layer 3, both wear resistance and chipping resistance can be improved, thus providing a cutting tool 10 with excellent tool life, especially in turning.
[0026] Cutting Tools like Figure 1 as well as Figure 2 As shown, a cutting tool 10 according to one embodiment of this disclosure includes a substrate 1 and a coating 2 disposed on the substrate 1. The coating 2 preferably covers the entire surface of the substrate 1, but even if a portion of the substrate 1 is not covered by the coating 2, or if the composition of the coating 2 is partially different, it does not depart from the scope of this embodiment. When a portion of the substrate 1 is not covered by the coating 2, it is preferable that the coating 2 is disposed such that it covers at least the surface of the substrate 1 involved in cutting. In this specification, although the portion of the substrate 1 involved in cutting also depends on the size and shape of the substrate 1, in this context, it refers to the area surrounded by an imaginary surface whose distance from its cutting edge ridge and the perpendicular line from the cutting edge ridge to the substrate 1 side along the tangent of the cutting edge ridge is, for example, any one of 5 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm.
[0027] The cutting tool 10 of this embodiment can be used as a drill bit, end mill, indexable cutting insert for drill bit, indexable cutting insert for end mill, indexable cutting insert for milling, indexable cutting insert for turning, metalworking saw, gear cutting tool, reamer, tap, and other cutting tools 10.
[0028] Substrate As the substrate 1, any substrate conventionally known as such substrate 1 can be used. For example, cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide with further additions of carbonitrides such as Ti, Ta, Nb, etc.), cermet (cermet with TiC, TiN, TiCN, etc. as the main components), high-speed steel, ceramic (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, alumina, etc.), cubic boron nitride sintered body or diamond sintered body.
[0029] Among these various substrates 1, WC-based cemented carbide and cermet (especially TiCN-based cermet) are particularly preferred. These substrates 1 have an excellent balance between hardness and strength at high temperatures, and therefore, when used as substrates 1 for cutting tools 10, they can contribute to the long service life of the cutting tool 10.
[0030] Covering The coating 2 includes a first layer 3. The coating 2 may consist solely of the first layer 3, or, without impairing the effects of this disclosure, the coating 2 may include layers other than the first layer 3 (hereinafter referred to as "other layers"). The thickness of the coating 2 may be 7 μm or more and 25 μm or less, or 10 μm or more and 15 μm or less. If the thickness of the coating 2 is less than 7 μm, the lifespan of the cutting tool 10 tends to be shortened due to the excessive thinness of the coating 2. On the other hand, if the thickness of the coating 2 is greater than 25 μm, the coating 2 is prone to cracking in the early stages of cutting, which also tends to shorten the lifespan of the cutting tool 10.
[0031] The thickness of the coating 2 can be determined by observing a cross-section of the coating 2 along the normal direction of its surface using a scanning electron microscope (SEM). Specifically, the magnification of the cross-sectional sample is set to 5,000 to 10,000 times, and the observation area is set to 100 to 500 μm. 2 The thickness of any three locations is measured in any field of view, and the average (arithmetic mean) is taken as the "thickness". The same applies to the thickness of each layer described later, unless otherwise specified.
[0032] The First Layer <Composition of the First Layer> The first layer 3 is composed of α-Al₂O₃. "Composed of α-Al₂O₃" can mean composed solely of α-Al₂O₃; however, without impairing the effects of this disclosure, it may also contain unavoidable impurities in addition to α-Al₂O₃. Examples of such unavoidable impurities include chlorine atoms (Cl) and sulfur atoms (S). The total content of unavoidable impurities in the first layer 3 can be, for example, 0% by mass or more and 0.10% by mass or less, or 0.01% by mass or more and 0.05% by mass or less. Furthermore, in this disclosure, the α-Al₂O₃ in the first layer 3 can be considered to exist as particles. The grain boundary GB, as described later, refers to the interface between a particle and its adjacent particles.
[0033] The composition of the first layer 3 as α-Al2O3 was determined by X-ray diffraction (XRD) and energy-dispersive X-ray diffraction (EDX). The unavoidable impurity content in the first layer 3 was determined by secondary ion mass analysis (SIMS). Furthermore, it was confirmed that as long as the measurement was performed in the same cutting tool 10, the measurement results were unbiased even if the measurement site was arbitrarily selected.
[0034] <Thickness of the first layer> The thickness of the first layer 3 is greater than 2 μm and less than 15 μm. The thickness of the first layer 3 can be greater than 3 μm and less than 14 μm, greater than 4 μm and less than 13 μm, or greater than 5 μm and less than 12 μm.
[0035] <Surface roughness Ra> The thickness of the first layer 3 is less than 8 μm. The surface roughness Ra of the surface S1 of the first layer 3, or the interface of the first layer 3 near the surface of the coating 2, can be 0.03 μm or more and 0.2 μm or less. This suppresses localized damage during surface treatment of the coating 2 and facilitates the uniform application of residual stress, thus providing superior tool life for the cutting tool 10, especially in turning operations. When the thickness of the first layer 3 is less than 8 μm, the surface roughness Ra can be 0.03 μm or more and 0.15 μm or less, or 0.03 μm or more and 0.1 μm or less.
[0036] The thickness of the first layer 3 is 8 μm or more. The surface roughness Ra of the surface S1 of the first layer 3, or the interface of the first layer 3 near the surface of the coating 2, can be 0.05 μm or more and 0.2 μm or less. This suppresses localized damage during surface treatment of the coating 2 and facilitates the uniform application of residual stress, thus providing superior tool life for the cutting tool 10, especially in turning operations. When the thickness of the first layer 3 is 8 μm or more, the surface roughness Ra can be 0.05 μm or more and 0.18 μm or less, or 0.06 μm or more and 0.15 μm or less.
[0037] The surface roughness Ra is measured according to JIS B0601:2001 in a cross-section along the blade tip R, which is normal to the interface between the substrate 1 and the coating 2. More specifically, firstly, an image is captured using SEM at 1000x magnification in the cross-section along the blade tip R, which is normal to the interface between the substrate 1 and the coating 2, thereby obtaining an image of the surface S1 of the first layer 3 or the surface of the first layer 3 located on the surface side of the coating 2. Next, in this image, any one of the 10μm × 10μm rectangular viewing fields is determined at 10000x magnification. In this viewing field, "the surface S1 of the first layer 3 or the surface of the first layer 3 located on the surface side of the coating 2" passes through any pair of opposite sides. Next, using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ), the contour information of the interface was extracted for the observation field, thereby determining the "arithmetic mean roughness" of the "surface S1 of the first layer 3, or the surface of the first layer 3 located on the surface side of the coating 2" in the observation field. Then, for any four other observation fields in the above image, the "arithmetic mean roughness" of the "surface S1 of the first layer 3, or the surface of the first layer 3 located on the surface side of the coating 2" was determined. Next, the surface roughness Ra was determined by calculating the average (arithmetic mean) of the "arithmetic mean roughness" of the "surface S1 of the first layer 3, or the surface of the first layer 3 located on the surface side of the coating 2" in a total of five observation fields. Furthermore, it was confirmed that as long as the same first layer 3 is measured, the measurement results are unbiased even if the measurement location is arbitrarily selected.
[0038] <Crystal boundary> In a cross-section along the normal to the interface between the substrate 1 and the coating 2, the first layer 3 includes a plurality of grain boundaries GB connecting the interface I1 of the first layer 3 near the substrate 1 to the surface S1 of the first layer 3 or the interface of the first layer 3 near the surface of the coating 2. At least one of the grain boundaries GB, namely the first grain boundary GB1, has a plurality of straight portions and three or more bends connecting two adjacent straight portions. This improves the "crack resistance" of the first layer 3.
[0039] In the first grain boundary GB1, the cross angle A1 at the nearest bend point to the interface I1 of the first layer 3 near the substrate 1 and the second nearest cross angle A2 are both 90° or more and 150° or less. In the first grain boundary GB1, the cross angle A4 at the nearest bend point to the interface of the first layer 3 near the surface S1 or the surface of the first layer 3 near the coating 2 and the second nearest cross angle A3 are both 120° or more and less than 180°. In the first grain boundary GB1, the average X1 of cross angles A1 and A2 and the average X2 of cross angles A3 and A4 satisfy the relationship of Equation 1.
[0040] X2-X1≥10° Formula 1 The upper limit for both cross angle A4 and cross angle A3 can be below 175° or below 170°.
[0041] The ratio N2 / N1, representing the number of first grain boundaries GB1, relative to the number of grain boundaries GB, is 0.2 or higher. This imparts excellent wear resistance and excellent fracture resistance to the first layer 3. The upper limit of the ratio N2 / N1 can be 1.0 or lower, or 0.7 or lower. The ratio N2 / N1 can be 0.3 or higher and 1.0 or lower, 0.4 or higher and 1.0 or lower, or 0.5 or higher and 1.0 or lower.
[0042] The ratio N2 / N1 can be determined by the following method.
[0043] (a1) For the cross section of the first layer 3 along the normal direction of the interface between the coating 2 and the substrate 1, electron beam backscatter diffraction image analysis is performed using a field emission scanning microscope, thereby producing a color image based on the crystal orientation of each particle (grain).
[0044] (b1) Based on the color image created in (a1), set the grain boundary GB of any particle (crystal particle) to white, and output the other parts as black, thereby obtaining the first image.
[0045] (c1) Starting from the left end of the image, observe the pixels in each column of the first image in sequence, and determine the part that first changes from black to white as "any grain boundary GB that connects the interface I1 of the first layer near the substrate and the surface S1 of the first layer or the interface of the first layer near the coating".
[0046] (d1) For each column of pixels of the grain boundary GB in the first image determined in (c1), the angle of the grain boundary GB in each pixel is obtained by fitting a rectangular region of size 15×15 pixels (i.e., 0.3μm×0.3μm) centered on that pixel in a first-order manner.
[0047] (e1) For any pixel in the grain boundary GB, if the angle calculated in (d1) is the largest or smallest among the pixels of the grain boundary GB in the column 0.4 μm above and below the column centered on that pixel, then that pixel is defined as a straight section. The location of the straight section near the substrate in the first layer connecting the straight section and the adjacent straight sections along the grain boundary is defined as the bending point, and the value obtained by subtracting the absolute value of the difference between the angles of each straight section calculated in (d1) from 180° is defined as the intersection angle at the bending point.
[0048] (f1) When there are multiple straight sections and three or more bends connecting two adjacent straight sections in the grain boundary GB determined in (c1), the intersection angles A1 and A2 closest to the bend point at the interface I1 closest to the substrate of the first layer are determined sequentially from the substrate side. Additionally, the intersection angles A4 and A3 closest to the bend point at the interface S1 or the surface of the first layer closest to the coating are determined sequentially from the interface side of the first layer.
[0049] (g1) Divide the sum of the cross angles A1 and A2 determined in (f1) by 2 to calculate the average X1. Also, divide the sum of the cross angles A3 and A4 determined in (f1) by 2 to calculate the average X2.
[0050] (h1) For “any other at least 17 grain boundaries GB that connect the interface I1 of the first layer near the substrate and the surface S1 of the first layer or the interface of the first layer near the coating surface”, by performing (f1) to (g1), the cross angle A1, cross angle A2, cross angle A3, cross angle A4, average X1 and average X2 are determined for each of the other at least 17 grain boundaries GB.
[0051] (i1) Among a total of 18 or more grain boundaries GB, the cross angles A1 and A2 are 90° or more and 150° or less, and the cross angles A4 and A3 are 120° or more and less than 180°. The number of grain boundaries GB (i.e., the first grain boundary GB1) whose average X1 and average X2 satisfy the relationship of Equation 1 is divided by the number of grain boundaries GB (i.e., 18 or more), thereby determining the "ratio N2 / N1 of the number of first grain boundaries GB1 N2 relative to the number of grain boundaries GB N1".
[0052] Furthermore, it was confirmed that as long as the same first layer 3 is measured, the measurement results will not be biased even if the measurement site is arbitrarily selected.
[0053] <The average distance D1 between two adjacent bending points along the normal to the interface between the substrate and the coating> In the first grain boundary GB1, the average distance D1 between two adjacent bending points along the normal to the interface between the substrate 1 and the coating 2 can be 0.05 μm or more and 4 μm or less. This easily improves the bending strength of the coating 2, thus providing superior tool life for the cutting tool 10, especially in turning operations. The average distance D1 can be 0.06 μm or more and 3 μm or less, 0.07 μm or more and 2 μm or less, or 0.08 μm or more and 1 μm or less.
[0054] The average distance D1 mentioned above can be determined using the following method.
[0055] (a2) By using the same method as described in (a1) to (g1) above, the cross angle A1, cross angle A2, average X1 and average X2 in the grain boundary GB are determined, thereby determining an arbitrary first grain boundary GB1.
[0056] (b2) In the first grain boundary GB1 determined in (a2), the absolute value of the difference between the columns of two adjacent straight sections along the grain boundary for all bending points is calculated (in other words, the absolute value of the difference of the distance [μm] from the end of the first layer near the substrate as 0 μm is taken from that position along the normal direction of the interface between the coating 2 and the substrate 1), and the average (arithmetic mean) of the absolute values of the difference is obtained, thereby determining the average distance of the two adjacent bending points along the normal direction of the interface between the substrate and the coating.
[0057] (c2) Using the same method as described in (a2) to (b2) above, for any other four first grain boundaries GB, the average distance between two adjacent bending points along the normal to the interface between the substrate and the coating is determined. The average distance D1 can be determined by dividing the sum of the average distances between two adjacent bending points along the normal to the interface between the substrate and the coating for each of the five first grain boundaries GB1 by 5.
[0058] Furthermore, it was confirmed that as long as the same first layer 3 is measured, the measurement results will not be biased even if the measurement site is arbitrarily selected.
[0059] <Orientation index TC (0 0 12) of the first layer> The orientation index TC (0 0 12) of the first layer 3 can be greater than 4.5. This further enhances the strength of the particles in the first layer 3 (in other words, the α-Al2O3 particles (crystal particles)), thereby further improving the wear resistance of the first layer 3. As a result, it imparts superior tool life to the cutting tool 10, especially in turning operations. The orientation index TC (0 0 12) of the first layer 3 can be greater than 4.5 and less than 8.0, greater than 5.0 and less than 7.9, greater than 6.0 and less than 7.9, or greater than 6.0 and less than 7.7.
[0060] Furthermore, in this specification, “the orientation index TC (0 0 12) of the first layer 3” refers to the orientation index TC (0 0 12) of the (0 0 12) face in the first layer 3, which is defined by the orientation index TC (hkl) in Equation 2 below.
[0061] [Number 1]
[0062] In Equation 2, I(hkl) represents the X-ray diffraction intensity of the (hkl) reflecting surface, and I0(hkl) represents the standard intensity based on the ICDD PDF card number 00-010-0173. Additionally, n in Equation 2 represents the reflection number used in the calculation, which is 8 in this embodiment. The (hkl) surfaces used for reflection are (012), (104), (110), (0 0 12), (113), (214), (116), and (300).
[0063] ICDD (registered trademark) is short for International Centre for Diffraction Data. PDF (registered trademark) is short for Powder Diffraction File.
[0064] Furthermore, the orientation index TC (0 0 12) of the first layer 3 in this embodiment can be represented by the following formula 3.
[0065] [Number 2]
[0066] Therefore, "the orientation index TC(0 0 12) of the first layer 3 is greater than 4.5" means that the value obtained by substituting TC(0 0 12) into the above equation 2 is greater than 4.5.
[0067] The determination of TC(hkl) as described above can be performed using an X-ray diffraction apparatus. TC(hkl) can be measured, for example, using a SmartLab (registered trademark) manufactured by Rigaku Co., Ltd. (scanning speed: 21.7° / min, step size: 0.01°, scan range: 15~140°) under the following conditions. Furthermore, in this embodiment, the result of the TC(hkl) determination using an X-ray diffraction apparatus is referred to as the "XRD result".
[0068] (condition) Characteristic X-rays: Cu-Kα Tube voltage: 45kV Tube current: 200mA Filter: Multilayer mirror Optical system: lumped method X-ray diffraction method: θ-2θ method When using an X-ray diffraction apparatus, X-rays are irradiated onto the rake face of the cutting tool. Typically, the rake face has irregularities, while the flank face is flat; therefore, to eliminate interference, it is preferable to irradiate the flank face with X-rays. In particular, X-rays are irradiated onto a portion of the flank face extending from the tool tip edge to approximately 2-4 mm. This improves the reproducibility of the results. Furthermore, in this embodiment, the orientation index TC(hkl) of the first layer 3 on the flank face of the substrate is the same as the TC(hkl) value of the first layer 3 on the rake face of the substrate.
[0069] Furthermore, it was confirmed that the same results could be obtained by arbitrarily selecting multiple measurement sites in the same sample and performing the above measurements on each site.
[0070] Other Layers Other layers may include, for example, a base layer (not shown), an intermediate layer (not shown), and a surface layer (not shown). The base layer is the layer in contact with the substrate 1. The surface layer is the layer located on the surface of the coating 2. The intermediate layer is the layer disposed between the base layer and the first layer 3, or between the first layer 3 and the surface layer.
[0071] <Basal layer> The substrate layer can also be composed of TiN or TiCN. "Composed of TiN or TiCN" means it can consist solely of TiN or TiCN, or it can contain unavoidable impurities in addition to TiN or TiCN. Examples of unavoidable impurities include chlorine (Cl), oxygen (O), cobalt (Co), tungsten (W), nickel (Ni), and boron (B). The total content of unavoidable impurities in the substrate layer can be, for example, 0% by mass or more and 1.0% by mass or less, or 0.3% by mass or more and 0.6% by mass or less.
[0072] The composition of the substrate layer as TiN or TiCN was determined using X-ray diffraction (XRD) and energy-dispersive X-ray diffraction (EDX). The unavoidable impurity content in the substrate layer was determined using secondary ion mass analysis (SIMS). Furthermore, it was confirmed that as long as the same substrate layer was measured, the results were unbiased even if the measurement site was arbitrarily selected.
[0073] The thickness of the substrate can be greater than 0.1 μm and less than 2.0 μm, greater than 0.5 μm and less than 1.5 μm, or greater than 0.8 μm and less than 1.3 μm.
[0074] <Intermediate Layer> The intermediate layer can be composed of TiCN. "Composed of TiCN" means it can consist solely of TiCN, or it can contain unavoidable impurities in addition to TiCN. Examples of unavoidable impurities include chlorine (Cl), oxygen (O), cobalt (Co), tungsten (W), nickel (Ni), and boron (B). The total content of unavoidable impurities in the intermediate layer can be, for example, 0% by mass or more and 1.0% by mass or less, or 0.3% by mass or more and 0.6% by mass or less.
[0075] The composition of the intermediate layer as TiCN was determined using X-ray diffraction (XRD) and energy-dispersive X-ray diffraction (EDX). The unavoidable impurity content in the intermediate layer was determined using secondary ion mass analysis (SIMS). Furthermore, it was confirmed that as long as the same intermediate layer was measured, the results were unbiased even if the measurement site was arbitrarily selected.
[0076] The thickness of the intermediate layer can be greater than 2.0 μm and less than 10 μm, or greater than 4.0 μm and less than 8.0 μm.
[0077] <Surface Layer> The surface layer can be composed of TiN. "Composed of TiN" means it can consist solely of TiN, or it can contain unavoidable impurities in addition to TiN. Examples of unavoidable impurities include chlorine (Cl), oxygen (O), cobalt (Co), tungsten (W), nickel (Ni), and boron (B). The total content of unavoidable impurities in the surface layer can be, for example, 0% by mass or more and 1.0% by mass or less, or 0.1% by mass or more and 0.4% by mass or less.
[0078] The TiN composition of the surface layer was determined using X-ray diffraction (XRD) and energy-dispersive X-ray diffraction (EDX). The unavoidable impurity content in the surface layer was determined using secondary ion mass analysis (SIMS). Furthermore, it was confirmed that as long as the same surface layer was measured, the results were unbiased even if the measurement site was arbitrarily selected.
[0079] The thickness of the surface layer can be greater than 0.5 μm and less than 3.0 μm, or greater than 1.0 μm and less than 2.5 μm.
[0080] [Implementation Method 2: Method for Manufacturing a Cutting Tool] use Figure 3 The manufacturing method of the cutting tool according to this embodiment will be described. Figure 3 This is a schematic cross-sectional view of an example of a CVD apparatus used to manufacture the cutting tools of this disclosure.
[0081] The method for manufacturing the cutting tool in this embodiment is the same as the method for manufacturing the cutting tool described in Embodiment 1. It includes a first step of preparing a substrate 1 and a second step of forming a coating on the substrate 1. The second step includes a 2a step of forming a first layer by CVD. The details of each step are described below.
[0082] The First Process In the first step, substrate 1 is prepared. Substrate 1 may be the substrate 1 described in Embodiment 1.
[0083] For example, when using cemented carbide as the substrate 1, commercially available substrate 1 can be used, or it can be manufactured using a conventional powder metallurgy method. In the case of manufacturing using a conventional powder metallurgy method, for example, WC powder and Co powder are mixed using a ball mill to obtain a mixed powder. After drying the mixed powder, it is shaped into a predetermined shape to obtain a molded body. Further, by sintering the molded body, a WC-Co based cemented carbide (sintered body) is obtained. Then, by performing predetermined tool tip machining such as honing on the sintered body, a substrate 1 made of WC-Co based cemented carbide can be manufactured. Even substrate 1 other than those described above, as long as it is a conventionally known substrate 1, can be prepared.
[0084] Second Process In the second process, a coating is formed on the substrate 1 to obtain the cutting tool. The coating is formed, for example, using... Figure 2 The CVD apparatus 50 shown is used for this process. The CVD apparatus 50 includes multiple substrate setting fixtures 52 for holding the substrate 1 and a heat-resistant alloy reaction vessel 53 covering the substrate setting fixtures 52. A temperature control device 54 for controlling the temperature inside the reaction vessel 53 is provided around the reaction vessel 53. A gas inlet pipe with a gas inlet is provided in the reaction vessel 53. The gas inlet pipe extends vertically within the internal space of the reaction vessel 53 where the substrate setting fixtures 52 are located and is configured to rotate about this vertical direction. Multiple ejection holes (through holes) are provided for ejecting gas into the reaction vessel 53. Using this CVD apparatus 50, a first layer constituting the above-described coating can be formed as follows.
[0085] The second step includes step 2a, which forms the first layer by CVD. If the coating includes the "other layers" described in Embodiment 1, the second step may further include a step for forming those "other layers." These "other layers" can be formed using conventionally known methods.
[0086] <Process 2a: Process for forming the first layer using CVD> In step 2a, a first layer is formed by CVD. More specifically, firstly, substrate 1 is placed in substrate setting fixture 52, and while controlling the temperature and pressure inside reaction vessel 53 within a predetermined range, the raw material gas for the first layer is introduced into reaction vessel 53 through a gas inlet pipe. Thus, a first layer is formed on substrate 1.
[0087] The CVD apparatus 50 is equipped with a nozzle 56 having two inlet ports 55 and 57. The nozzle 56 is arranged to pass through the area where the substrate setting fixture 52 is arranged. A plurality of injection holes (first injection hole 61, second injection hole 62, third injection hole (not shown) and fourth injection hole (not shown)) are formed in the portion of the nozzle 56 near the substrate setting fixture 52.
[0088] The gases introduced into the nozzle 56 from the inlet 55 and inlet 57 do not mix within the nozzle 56, but are instead introduced into the reaction vessel 53 through different injection holes. The nozzle 56 can rotate about this axis. Furthermore, 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. Additionally, the fixtures and other components within the reaction vessel 53 are typically made of graphite.
[0089] The raw material gas is a mixture of AlCl3, HCl, CO2, H2S, and H2.
[0090] First, in order to form the region of the first layer near the substrate, (001) film formation and (110) film formation are alternately and repeatedly performed under the following conditions (step I). In step I, the film formation time for (001) film formation is set to 5 to 180 minutes, and the rotation speed of the (001) film formation nozzle is set to 0.5 to 4 rpm. Additionally, in step I, the film formation time for (110) film formation is set to 5 to 180 minutes, and the rotation speed of the (110) film formation nozzle is set to 0.5 to 6 rpm. Next, in order to form the region of the first layer near the coated surface, (001) film formation and (110) film formation are alternately and repeatedly performed under the following conditions (step II). In step II, the film formation time for (001) film formation is set to 4 to 90 minutes, and the rotation speed of the (001) film formation nozzle is set to 0.2 to 2 rpm. In addition, in step II, the film-forming time of (110) is set to 4 to 90 minutes, and the rotation speed of the (110) film-forming nozzle is set to 0.4 to 4 rpm. The rotation speed of the (001) film-forming nozzle in step I is at least 0.1 rpm faster than the rotation speed of the (001) film-forming nozzle in step II. In other words, "(rotation speed of the (001) film-forming nozzle in step I) - (rotation speed of the (001) film-forming nozzle in step II)" is at least 0.1 rpm. The rotation speed of the (001) film-forming nozzle in step I can be at least 0.5 rpm faster than the rotation speed of the (001) film-forming nozzle in step II, or at least 1 rpm faster. The rotation speed of the (110) film-forming nozzle in step I is at least 0.1 rpm faster than the rotation speed of the (110) film-forming nozzle in step II. In other words, the rotational speed of the nozzle for film formation in step I (110) - the rotational speed of the nozzle for film formation in step II (110) is 0.1 rpm or more. The rotational speed of the nozzle for film formation in step I (110) can be 0.5 rpm or more faster than the rotational speed of the nozzle for film formation in step II (110), or it can be 1 rpm or more faster. The total number of times the film formation is performed in step I (001) and step II (001) is 2 or more, and the total number of times the film formation is performed in step I (110) and step II (110) is 2 or more. As a result, a first grain boundary having multiple straight sections and three or more bending points connecting two adjacent straight sections can be formed. Furthermore, the film formation in step I (001) is performed by injecting a mixed gas from the first injection hole 61 and the second injection hole 62, and the film formation in step II (110) is performed by injecting a mixed gas from the third injection hole (not shown) and the fourth injection hole (not shown). In each of steps I and II, film formation can begin at (001) or at (110).
[0091] <(001) Conditions for film formation> AlCl3: 0.005~0.02% by volume HCl: 0.01~0.05% (volume %) CO2: 1.5~6.0% by volume H2S: 0.3~1.0% by volume H2: Balance Temperature: 950~1050℃ Pressure: 50~200 hPa Flow rate: 15~60L / minute <(110) Conditions for film formation> AlCl3: 0.01~0.04% by volume HCl: 0.01~0.05% (volume %) CO2: 2.5~10% by volume H2S: 0.02~0.08% by volume H2: Balance Temperature: 950~1050℃ Pressure: 50~150 hPa Flow rate: 20~40L / minute There is no particular limitation on the number of times (001) and (110) film formation are performed. The thickness of the first layer can be adjusted by appropriately adjusting the number of times (001) and (110) film formation are performed.
[0092] <Other processes> The second process, in addition to the above processes, may also include surface treatment processes such as surface grinding and sandblasting.
[0093] Features of the Manufacturing Method of the Cutting Tool of this Embodiment In the manufacturing method of the cutting tool in this embodiment, in step 2a, film formation (001) with a film formation time of 4 to 180 minutes and a nozzle rotation speed of 0.5 to 4 rpm and film formation (110) with a film formation time of 4 to 180 minutes and a nozzle rotation speed of 0.5 to 6 rpm are alternately performed (step I). Then, film formation (001) with a film formation time of 4 to 90 minutes and a nozzle rotation speed of 0.2 to 2 rpm and film formation (110) with a film formation time of 4 to 90 minutes and a nozzle rotation speed of 0.4 to 4 rpm are alternately performed (step II). Film formation (001) is performed by injecting a mixed gas from the first injection hole and the second injection hole, and film formation (110) is performed by injecting a mixed gas from the third injection hole and the fourth injection hole. The rotational speed of the nozzle for film formation (001) in step I is at least 0.1 rpm faster than the rotational speed of the nozzle for film formation (001) in step II, and the rotational speed of the nozzle for film formation (110) in step I is at least 0.1 rpm faster than the rotational speed of the nozzle for film formation (110) in step II. The total number of film formations (001) in step I and (001) in step II is at least 2, and the total number of film formations (110) in step I and (110) in step II is at least 2. As a result, in the region of the first layer near the substrate, the cross angle at the grain boundaries can be suppressed to be relatively small, and in the region of the first layer near the surface of the coating, the cross angle at the grain boundaries can be relatively large. Therefore, the cross angles A1, A2, A3, and A4, the average X1 of cross angle A1 and A2, and the average X2 of cross angles A3 and A4 can be adjusted to desired ranges, and the ratio N2 / N1 of the number of first grain boundaries N2 to the number of grain boundaries N1 can be adjusted to desired ranges. The inventors of this invention, through in-depth research, discovered that the cutting tool of this disclosure can be realized by employing such a manufacturing method.
[0094] Example The present embodiment will be further described in detail through the examples. However, the present embodiment is not limited to these examples.
[0095] Making Cutting Tools The cutting tools involved in making specimens 1-19 and specimens 101-104 are prepared as follows.
[0096] The First Process As a base material, a turning insert with the following composition is prepared (shape: manufactured by Sumitomo Electric Carbide Co., Ltd., CNMG120408N-GZ).
[0097] (Composition of the substrate) Co content: 6.0% by mass TaC content: 1.5% by mass WC content: Balance Second Process A first layer is formed on the surface of the substrate by performing CVD (step 2a). First, for samples 1-19, 101, 102, and 104, film formation with the film formation time as described in Table 1 and the nozzle rotation speed as described in Table 1 (001) and film formation with the film formation time as described in Table 1 and the nozzle rotation speed as described in Table 1 (110) are performed alternately as described in the "Number of Repetitions [times]" column of Table 1 (step I). Next, for samples 1-19, 101, 102, and 104, film formation with the film formation time as described in Table 2 and the nozzle rotation speed as described in Table 2 (001) and film formation with the film formation time as described in Table 2 and the nozzle rotation speed as described in Table 2 (110) are performed alternately as described in the "Number of Repetitions [times]" column of Table 2 (step II). Furthermore, for sample 103, one film formation (step I) was performed with the film formation time as described in Table 1 and the nozzle rotation speed as described in Table 1. For sample 103, step II was not performed. In addition, for samples 1 to 19 and samples 101 to 103, the number of spray holes in the (001) film formation was "two", and the number of spray holes in the (110) film formation was "two". In addition, for sample 104, the number of spray holes in the (001) film formation was "one", and the number of spray holes in the (110) film formation was "one". In addition, in steps I and II, film formation started from (001) respectively. In addition, "(rotation speed of the nozzle for (001) film formation in step I) - (rotation speed of the nozzle for (001) film formation in step II)" and "(rotation speed of the nozzle for (110) film formation in step I) - (rotation speed of the nozzle for (110) film formation in step II)" are respectively described in Table 3. Regarding film formation (001) and film formation (110), the conditions other than film formation time and nozzle rotation speed are described below.
[0098] <(001) Conditions for film formation> AlCl3: 0.01% by volume HCl: 0.025% (v / v) CO2: 3.20% by volume H2S: 0.64% by volume H2: Balance Temperature: 1000℃ Pressure: 100 hPa Flow rate: 35L / minute <(110) Conditions for film formation> AlCl3: 0.02% by volume HCl: 0.025% (v / v) CO2: 5.00% by volume H2S: 0.04% by volume H2: Balance Temperature: 1000℃ Pressure: 100 hPa Flow rate: 30L / minute Next, the surface of the first layer is sandblasted under the following conditions.
[0099] (condition) Types of media: ceramic Average particle size of the medium: 50 μm Medium concentration: 100g / min Projection angle: 75° Projection distance: 35mm Projection pressure: as described in Table 3 Time: 10 seconds Cutting tool rotation speed: 60 rpm Based on the above, the cutting tools involved in samples 1-19 and 101-104 were produced.
[0100] [Table 1]
[0101] [Table 2]
[0102] [Table 3]
[0103] [Table 4]
[0104] Evaluation of Cutting Tool Characteristics <Composition of the First Layer> For each cutting tool involved in the test specimens, the composition of the first layer was determined using the method described in Embodiment 1. The results were recorded in the "Composition" column of the "First Layer" section of Table 4. Furthermore, if a component name is recorded in the "Composition" column of the "First Layer" section of Table 4, it means that the first layer is composed of the component represented by that component name.
[0105] <Thickness of the first layer> For each sample and the cutting tool involved, the thickness of the first layer was determined using the method described in Embodiment 1. The results were recorded in the "Thickness [μm]" column of the "First Layer" section of Table 4.
[0106] <Ratio N2 / N1> For each sample and the cutting tool involved, the number of grain boundaries N1, the number of first grain boundaries N2, and the ratio N2 / N1 were determined by the method described in Embodiment 1. The results were recorded in the "N1 [pieces]", "N2 [pieces]", and "N2 / N1" columns of Table 4, respectively.
[0107] <The average distance D1 between two adjacent bending points along the normal to the interface between the substrate and the coating> For each sample and the cutting tool involved, the average distance D1 between two adjacent bending points along the normal to the interface between the substrate and the coating was determined at the first grain boundary using the method described in Embodiment 1. The results were recorded in the "D1 [μm]" column of Table 4.
[0108] <Surface roughness Ra of the surface of the first layer or the interface of the first layer located on the side of the coated surface> The surface roughness Ra is determined on the surface of the first layer, or on the interface of the first layer located on the surface side of the coating, using the method described in Embodiment 1. The results are recorded in the "Ra [μm]" column of Table 4.
[0109] <Orientation index TC (0 0 12) of the first layer> For each sample, the orientation index TC (0 0 12) of the first layer was determined using the method described in Embodiment 1. The results were recorded in the "TC (0012)" column of the "First Layer" column in Table 4.
[0110] Cutting Test 1 Using the cutting tools involved in each test specimen, cutting was performed under the following cutting conditions. The time from the start of cutting to when the flank wear (Vb) exceeded 0.2 mm, and the shorter of the time from the start of cutting to when chipping occurred, were measured. The results were recorded in the "Time [minutes]" column of "Cutting Test 1" in Table 4.
[0111] (Cutting conditions) Material to be cut: FCD700 round bar (diameter: 300mm, length: 1000mm) Machining method: Outer diameter contour machining Processing speed V: 200m / min Feed rate f: 0.3 mm / rev Cutting depth (ap): 1.5mm Cutting fluid: None The cutting conditions described above are equivalent to those for turning.
[0112] Cutting Test 2 Using the cutting tools involved in each test specimen, cutting was performed under the following cutting conditions. The time from the start of cutting to the occurrence of defects was measured and recorded as the cutting time. However, if no defects occurred after 5 minutes, the cutting time was set to 5 minutes. The results were recorded in the "Time [minutes]" column of "Cutting Test 2" in Table 4.
[0113] (Cutting conditions) Material to be cut: FCD450-4 sheet metal (diameter: 300mm, length: 1000mm, groove width 20mm × depth 100mm × 4 sheets × diagonal (90°)) Machining method: Outer diameter contour machining Processing speed V: 150m / min Feed rate f: 0.3 mm / rev Cutting depth (ap): 1.5mm Cutting fluid: Available The cutting conditions described above are equivalent to those for turning.
[0114] A cutting time of more than 3.0 minutes in cutting test 1 and more than 2.5 minutes in cutting test 2 indicates that the cutting tool has excellent tool life.
[0115] The cutting tools involved in specimens 1-19 correspond to the examples. The cutting tools involved in specimens 101-104 correspond to the comparative examples. According to the results of cutting test 1 and cutting test 2 in Table 4, the cutting tools involved in specimens 1-19 have excellent tool life compared with the cutting tools involved in specimens 101-104.
[0116] As can be seen from the above, the cutting tools involved in samples 1 to 19 have excellent tool life.
[0117] 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.
[0118] 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.
[0119] Explanation of reference numerals in the attached figures 1: Substrate; 2: Coating; 3: First layer; 10: Cutting tool; 50: CVD apparatus; 52: Substrate setting fixture; 53: Reaction vessel; 54: Temperature control device; 55, 57: Inlet; 56: Nozzle; 59: Exhaust pipe; 60: Exhaust port; 61: First injection hole; 62: Second injection hole; GB: Grain boundary; GB1: First grain boundary; S1: Surface; I1: Interface.
Claims
1. A cutting tool comprising a substrate and a coating disposed on the substrate, wherein, The coating comprises a first layer. The first layer is composed of α-Al₂O₃. The thickness of the first layer is greater than 2 μm and less than 15 μm. In a cross-section along the normal to the interface between the substrate and the coating, the first layer includes a plurality of grain boundaries connecting the interface of the first layer near the substrate to the surface of the first layer or the interface of the first layer near the surface of the coating, wherein at least one grain boundary, i.e., the first grain boundary, has a plurality of straight portions and three or more bends connecting two adjacent straight portions. In the first grain boundary, the cross angle A1 at the nearest bend point to the interface of the first layer near the substrate and the second nearest cross angle A2 are both greater than 90° and less than 150°. In the first grain boundary, the intersection angle A4 at the nearest bend point to the surface of the first layer or the interface of the first layer near the surface of the coating, and the second nearest intersection angle A3, are both greater than 120° and less than 180°. In the first grain boundary, the average X1 of the crossing angles A1 and A2 and the average X2 of the crossing angles A3 and A4 satisfy the relationship of Equation 1. The ratio N2 / N1, representing the number of the first grain boundaries N2 relative to the number of grain boundaries N1, is 0.2 or more. X2-X1≥10° Equation 1.
2. The cutting tool according to claim 1, wherein, In the first grain boundary, the average distance D1 between two adjacent bending points along the normal of the interface between the substrate and the coating is greater than 0.05 μm and less than 4 μm.
3. The cutting tool according to claim 1 or 2, wherein, The thickness of the first layer is less than 8 μm. In the surface of the first layer, or in the interface of the first layer located near the surface of the coating, the surface roughness Ra is 0.03 μm or more and 0.2 μm or less.
4. The cutting tool according to claim 1 or 2, wherein, The thickness of the first layer is 8 μm or more. In the surface of the first layer, or in the interface of the first layer located near the surface of the coating, the surface roughness Ra is 0.05 μm or more and 0.2 μm or less.
5. The cutting tool according to any one of claims 1 to 4, wherein, The orientation index TC (0 0 12) of the first layer is greater than 4.5.
Citation Information
Patent Citations
Alumina coated cutting tool with zigzag alumina grain boundaries
WO2015113866A1