Cutting Tools

Abstract

A cutting tool comprising a substrate and a coating disposed on the substrate, the coating including a first layer located on the substrate and a second layer located on the first layer, the first layer made of α-Al2O3 and the second layer made of TiCN, a thickness of the second layer is equal to or greater than 0.5 μm and less than 2.0 μm, and a residual stress X of the second layer is equal to or greater than -2.0 GPa and equal to or less than -0.5 GPa.

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, cutting tools including a substrate and a coating disposed on the substrate have been used in cutting processes (Patent Documents 1 to 6). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-037150 A [Patent Document 2] JP 2020-116645 A [Patent Document 3] International Publication No. 2009 / 112116 [Patent Document 4] International Publication No. 2022 / 244241 [Patent Document 5] International Publication No. 2022 / 244242 [Patent Document 6] International Publication No. 2022 / 244243 Summary of the Invention

[0004] The cutting tool of the present disclosure comprises: 1. A cutting tool comprising a substrate and a coating disposed on the substrate, The coating includes a first layer disposed on the substrate and a second layer disposed on the first layer; The first layer is α-Al 2 O 3 It consists of: the second layer is made of TiCN; The thickness of the second layer is equal to or greater than 0.5 μm and less than 2.0 μm, The second layer has a residual stress X of −2.0 GPa or more and −0.5 GPa or less. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a cutting tool according to the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional view illustrating another embodiment of the cutting tool of the present disclosure. [Diagram 3] FIG. 3 is a schematic cross-sectional view illustrating another embodiment of the cutting tool of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view of an example of a CVD (Chemical Vapor Deposition) apparatus used in manufacturing the cutting tool of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] [Problem that this disclosure aims to solve] In recent years, there has been an increasing demand for improved tool life, particularly in the interrupted turning of cast iron. Important factors for further improving tool life in the interrupted turning of cast iron include "wear resistance" and "chipping resistance." In addition, from the viewpoint of improving the cutting performance of a cutting tool in the interrupted turning of cast iron, a cutting tool is provided that includes a substrate and a coating disposed on the substrate, and the coating is an α-Al Cr-Al-Al-Fe-Ni-Ni-Zn-Al-Fe ... 2 O 3 layer and the α-Al 2 O 3 and a TiCN layer disposed on the α-Al layer. 2 O 3Since the TiCN layer is formed by the CVD method, the TiCN layer is formed by the CVD method. Here, the TiCN layer contributes to the "wear resistance" and "chipping resistance" of the coating. In particular, from the viewpoint of improving the "wear resistance", a cutting tool is used in which the thickness of the TiCN layer is 0.5 μm or more and less than 2.0 μm. However, in such a cutting tool, when a high compressive residual stress is to be imparted in order to impart better cutting performance, the TiCN layer is easily worn away due to the thin thickness of the TiCN layer, and it is sometimes difficult to provide both excellent "wear resistance" and excellent "chipping resistance". Therefore, it is required to extend the tool life, especially in the intermittent turning of cast iron, by providing both excellent "wear resistance" and excellent "chipping resistance".

[0007] Therefore, an object of the present disclosure is to provide a cutting tool having a long tool life, particularly in intermittent turning of cast iron.

[0008] [Effects of this disclosure] According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in interrupted turning of cast iron.

[0009] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. (1) The cutting tool of the present disclosure comprises: 1. A cutting tool comprising a substrate and a coating disposed on the substrate, the coating includes a first layer overlying the substrate and a second layer overlying the first layer; The first layer is α-Al 2 O 3 It consists of: the second layer is made of TiCN; The thickness of the second layer is equal to or greater than 0.5 μm and less than 2.0 μm, The second layer has a residual stress X of −2.0 GPa or more and −0.5 GPa or less.

[0010] According to the present disclosure, a cutting tool having a long tool life can be provided, particularly in interrupted turning of cast iron.

[0011] (2) In the above item (1), the first layer may have a thickness of 3.0 μm or more and 15.0 μm or less, thereby providing a cutting tool having a longer tool life, particularly in intermittent turning of cast iron.

[0012] (3) In the above (1) or (2), the orientation index TC(0 0 12) of the first layer may be 3.0 or more, thereby providing a cutting tool having a longer tool life, particularly in interrupted turning of cast iron.

[0013] (4) In any one of the above (1) to (3), the coating further includes a third layer located between the substrate and the first layer, the third layer is made of TiCN; The residual stress Y of the third layer may be −1.0 GPa or more and 1.0 GPa or less, thereby providing a cutting tool having a longer tool life, particularly in interrupted turning of cast iron.

[0014] [Details of the embodiment of the present disclosure] A specific example of a cutting tool according to an embodiment of the present disclosure (hereinafter also referred to as the "present embodiment") will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference symbols represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0015] In this specification, the expression "A to B" means the upper and lower limits of a range (i.e., A or more and B or less). When no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0016] In the present disclosure, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is intended to include any conventionally known atomic ratio, and should not necessarily be limited to only those within the stoichiometric range.

[0017] [Embodiment 1: Cutting tool] A cutting tool according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 3. FIG. One embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") is A cutting tool 10 comprising a substrate 1 and a coating 2 disposed on the substrate 1, The coating 2 includes a first layer 3 located on the substrate 1 and a second layer 4 located on the first layer 3, The first layer 3 is made of α-Al 2 O 3 It consists of: The second layer 4 is made of TiCN, The thickness of the second layer 4 is equal to or greater than 0.5 μm and less than 2.0 μm. The residual stress X of the second layer 4 is not less than −2.0 GPa and not more than −0.5 GPa.

[0018] According to the present disclosure, it is possible to provide a cutting tool 10 having a long tool life, particularly in interrupted turning of cast iron. The reason for this is presumably as follows.

[0019] (a) The thickness of the second layer 4 is equal to or greater than 0.5 μm and less than 2.0 μm. This can improve the “wear resistance” of the cutting tool 10.

[0020] (b) As described above, the "wear resistance" of the cutting tool 10 can be improved by making the thickness of the second layer 4 0.5 μm or more and less than 2.0 μm. However, when attempting to impart high compressive residual stress to further improve the cutting performance of the cutting tool 10 by simply making the thickness of the second layer 4 0.5 μm or more and less than 2.0 μm, the second layer 4 may be easily worn away due to its thin thickness. Therefore, even in the intermittent turning of cast iron in particular, it may be difficult to provide a cutting tool 10 having a long tool life with both excellent "wear resistance" and excellent "chipping resistance."

[0021] (c) In the cutting tool 10 according to this embodiment, the residual stress X of the second layer 4 is −2.0 GPa or more and −0.5 GPa or less. 2 O 3 Since excellent compressive residual stress can be imparted to the surface side of the coating through the layer made of (that is, the first layer), the "chipping resistance" of the cutting tool 10 can be improved.

[0022] ≪Cutting tools≫ As shown in FIGS. 1 to 3, a cutting tool 10 according to an embodiment of the present 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 part of the substrate 1 is not covered with the coating 2 or the configuration of the coating 2 is partially different, this does not depart from the scope of this embodiment. When a part of the substrate 1 is not covered with the coating 2, the coating 2 may be disposed so as to cover at least the surface of the part of the substrate 1 involved in cutting. In this specification, the part of the substrate 1 involved in cutting means, depending on the size and shape of the substrate 1, a region of the substrate 1 surrounded by the cutting edge ridge and a virtual surface whose distance from the cutting edge ridge to the substrate 1 along the perpendicular to the tangent to the cutting edge ridge is, for example, 5 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm.

[0023] The cutting tool 10 of this embodiment can be suitably used as cutting tools 10 such as drills, end mills, indexable cutting tips for drills, indexable cutting tips for end mills, indexable cutting tips for milling, indexable cutting tips for turning, metal saws, gear cutting tools, reamers, taps, etc.

[0024] ≪Base material≫ Any of the conventionally known substrates 1 can be used as the substrate 1. For example, the substrate 1 is preferably any of the following: cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide containing carbonitrides of Ti, Ta, Nb, etc.), cermet (mainly composed of TiC (titanium carbide), TiN (titanium nitride), TiCN (titanium carbonitride), etc.), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride sintered body, and diamond sintered body.

[0025] It is particularly preferable to select a WC-based cemented carbide or a cermet (particularly a TiCN-based cermet) from among these various substrates 1. These substrates 1 have an excellent balance between hardness and strength, particularly at high temperatures, and therefore, when used as the substrate 1 of a cutting tool 10, they can contribute to extending the life of the cutting tool 10.

[0026] ≪Coating≫ The coating 2 includes a first layer 3 located on the substrate 1 and a second layer 4 located on the first layer 3. The coating 2 improves various properties of the cutting tool 10, such as wear resistance and chipping resistance, by covering the substrate 1, and has the effect of extending the life of the cutting tool 10. The effect of the present disclosure can be achieved by the second layer being present in a part or the entire area of ​​the part involved in cutting. The coating 2 may be composed of a first layer 3 located on the substrate 1 and a second layer 4 located on the first layer 3. The coating 2 may further include a third layer 5 located between the substrate 1 and the first layer 3. The coating 2 may be composed of a first layer 3 located on the substrate 1, a second layer 4 located on the first layer 3, and a third layer 5 located between the substrate 1 and the first layer 3. The coating 2 may further include a fourth layer 6 located on the second layer 4. The coating 2 may be composed of a first layer 3 located on the substrate 1, a second layer 4 located on the first layer 3, and a fourth layer 6 located on the second layer 4. The coating 2 may be composed of the first layer 3 located on the substrate 1, the second layer 4 located on the first layer 3, a third layer 5 located between the substrate 1 and the first layer 3, and a fourth layer 6 located on the second layer 4. The coating 2 may include "other layers" described below in addition to the first layer 3, the second layer 4, and the third layer 5, as long as the effects of the present disclosure are not impaired.

[0027] The thickness of the coating 2 may be 3.5 μm or more and 30.0 μm or less. If the thickness of the coating 2 is less than 3.5 μm, the coating 2 is too thin, and the life of the cutting tool 10 tends to be shortened. On the other hand, if the thickness of the coating 2 exceeds 30.0 μm, chipping of the coating 2 is likely to occur in the early stage of cutting, and the life of the cutting tool 10 tends to be shortened. The thickness of the coating 3 can be measured by observing the cross section of the coating 2 using a scanning electron microscope (SEM). Specifically, the observation 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 width is measured at three arbitrary points in one visual field, and the average value is taken as the "thickness." The same applies to the thickness of each layer described below unless otherwise specified.

[0028] <1st layer> <Composition of the first layer> The first layer 3 is α-Al 2 O 3 (In other words, α-alumina). 2 O 3 "consisting of" refers to α-Al as long as the effect of the present disclosure is shown. 2 O 3 In addition to the above, the first layer 3 may contain unavoidable impurities. Examples of the unavoidable impurities include chlorine atoms (Cl). The total content of the unavoidable impurities in the first layer 3 may be more than 0 mass% or less than 3 mass%.

[0029] The first layer 3 is α-Al 2 O 3 The fact that the first layer 3 is made up of is measured by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The content of inevitable impurities in the first layer 3 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that, as long as the measurements are performed using the same cutting tool 10, there is no variation in the measurement results even if the measurement points are arbitrarily selected.

[0030] <First layer structure> The thickness of the first layer 3 may be 3.0 μm or more and 15.0 μm or less. This allows the cutting tool 10 to have both better wear resistance and better chipping resistance, so that it is possible to provide a cutting tool 10 having a longer tool life, especially in intermittent turning of cast iron. The thickness of the first layer 3 may be 3.2 μm or more and 13.1 μm or less, or 3.5 μm or more and 10.2 μm or less.

[0031] <First layer orientation index TC(0 0 12)> The orientation index TC(0.012) of the first layer 3 may be 3.0 or more. This makes it possible to achieve both better wear resistance and better chipping resistance, and therefore it is possible to provide a cutting tool 10 having a longer tool life, particularly in intermittent turning of cast iron. The orientation index TC(0.012) of the first layer 3 may be 3.0 or more and 8.0 or less, 3.1 or more and 7.7 or less, or 3.2 or more and 7.4 or less.

[0032] In this specification, "the orientation index TC(0 0 12) of the first layer 3" means the orientation index TC(0 0 12) of the (0 0 12) plane in the first layer 3, among the orientation index TC(hkl) defined by the following formula 1.

[0033]

number

[0034] In formula 1, I(hkl) represents the X-ray diffraction intensity of the (hkl) reflection plane, and I 0 (hkl) indicates the standard intensity according to ICDD PDF card number 00-010-0173. In addition, n in formula 1 indicates the number of reflections used in the calculation, which is 8 in this embodiment. The (hkl) planes used for reflection are (012), (104), (110), (0 0 12), (113), (024), (116), and (300).

[0035] ICDD (registered trademark) is the abbreviation for International Centre for Diffraction Data, and PDF (registered trademark) is the abbreviation for Powder Diffraction File.

[0036] The orientation index TC (0 0 12) of the first layer 3 in this embodiment can be expressed by the following formula 2.

[0037]

number

[0038] Therefore, "the orientation index TC(0 0 12) of the first layer 3 is 3.0 or more" means that the value obtained by the above formula 2 obtained by substituting TC(0 0 12) into the above formula 1 is 3.0 or more.

[0039] The above-mentioned measurement of TC(hkl) is possible by analysis using an X-ray diffraction apparatus. TC(hkl) can be measured, for example, using Rigaku Corporation's SmartLab (registered trademark) (scan speed: 21.7° / min, step: 0.01°, scan range: 15-140°) under the following conditions. In this embodiment, the measurement result of TC(hkl) using an X-ray diffraction apparatus is referred to as "XRD result". (conditions) Characteristic X-ray: Cu-Kα Tube voltage: 45kV Tube current: 200mA Filter: Multi-layer mirror Optics: Concentration method X-ray diffraction method: θ-2θ method When using an X-ray diffraction device, X-rays are irradiated onto the rake face of a cutting tool. Usually, the rake face has irregularities, whereas the flank face is flat. Therefore, it is preferable to irradiate the flank face with X-rays in order to eliminate disturbance factors. In particular, X-rays are irradiated onto a portion of the flank face that extends within a range of about 2 to 4 mm from the cutting edge ridge. This increases the reproducibility of the results. In this embodiment, the value of the orientation index TC(hkl) of the first layer 3 on the flank face of the substrate is the same as the value of TC(hkl) of the first layer 3 on the rake face of the substrate. In this embodiment, it was confirmed that similar results could be obtained even if multiple measurement points were arbitrarily selected from the same sample and the above measurement was performed for each measurement point.

[0040] The orientation index TC (0 0 12) of the first layer 3 is determined by the H 2 By appropriately adjusting the S content [vol %], it is possible to make it fall within a desired range.

[0041] <2nd layer> <Composition of the second layer> The second layer 4 is made of TiCN. Here, "made of TiCN" means that in addition to TiCN, inevitable impurities can be contained, as long as the effect of the present disclosure is exhibited. Examples of the inevitable impurities include chlorine atoms (Cl). The total content of inevitable impurities in the second layer 4 may be more than 0 mass% or less than 3 mass%.

[0042] The fact that the second layer 4 is made of TiCN is measured by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The content of inevitable impurities in the second layer 4 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that, as long as the measurements are performed using the same cutting tool 10, there is no variation in the measurement results even if the measurement points are arbitrarily selected.

[0043] <Second layer structure> The thickness of the second layer 4 is 0.5 μm or more and less than 2.0 μm, which can improve the "wear resistance" of the cutting tool 10. The thickness of the second layer 4 may be 0.6 μm or more and 1.8 μm or less, or may be 0.7 μm or more and 1.7 μm or less.

[0044] <Residual stress in the second layer> The residual stress X of the second layer 4 is -2.0 GPa or more and -0.5 GPa or less. This can improve the "chipping resistance" of the cutting tool 10. The residual stress X of the second layer 4 may be -1.9 GPa or more and -0.6 GPa or less, or may be -1.8 GPa or more and -0.9 GPa or less.

[0045] "Residual stress" is a type of internal stress (intrinsic strain) present in a layer. Residual stress is broadly divided into compressive residual stress and tensile residual stress. Compressive residual stress refers to residual stress expressed as a "-" (negative) numerical value (in this specification, the unit is "GPa"). For example, "compressive residual stress of 10 GPa" can be understood as a residual stress of -10 GPa. Therefore, the concept of a large compressive residual stress indicates that the absolute value of the above numerical value is large, and the concept of a small compressive residual stress indicates that the absolute value of the above numerical value is small. Tensile residual stress refers to residual stress expressed as a "+" (plus) numerical value (in this specification, the unit is "GPa"). For example, "tensile residual stress of 10 GPa" can be understood as a residual stress of 10 GPa. Therefore, the concept of a large tensile residual stress indicates that the above numerical value is large, and the concept of a small tensile residual stress indicates that the above numerical value is small.

[0046] The residual stress X of the second layer 4 can be determined by measuring the second layer 4 with an X-ray residual stress device using the sin2ψ method (see pages 54-66 of "X-Ray Stress Measurement Method" (published by Yokendo Co., Ltd. in 1981 by the Japan Society for Materials Science)). The temperature during the measurement is room temperature (20°C). It has also been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected, as long as the measurement is performed using the same cutting tool 10.

[0047] <3rd layer> <Composition of the third layer> The third layer 5 is made of TiCN. Here, "made of TiCN" means that in addition to TiCN, inevitable impurities can be contained as long as the effect of the present disclosure is exhibited. Examples of the inevitable impurities include chlorine atoms (Cl). The total content of inevitable impurities in the third layer 5 may be more than 0 mass% or less than 3 mass%.

[0048] It is determined by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) that the third layer 5 is made of TiCN. The content of inevitable impurities in the third layer 5 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that, as long as the measurements are performed using the same cutting tool 10, there is no variation in the measurement results even if the measurement points are arbitrarily selected.

[0049] <Structure of the third layer> The thickness of the third layer 5 may be 2 μm or more and 12 μm or less. This allows both superior chipping resistance and superior wear resistance to be achieved, and therefore a cutting tool having a longer tool life can be provided, particularly in intermittent turning of cast iron. The thickness of the third layer 5 may be 4 μm or more and 10 μm or less, or 5 μm or more and 7 μm or less.

[0050] <Residual stress in the third layer> The residual stress Y of the third layer 5 may be -1.0 GPa or more and 1.0 GPa or less. This can impart better wear resistance and better chipping resistance to the cutting tool 10, and therefore a cutting tool having a longer tool life can be provided, particularly in intermittent turning of cast iron. The residual stress Y of the third layer 5 may be -1.0 GPa or more and 0.5 GPa or less, or -1.0 GPa or more and 0.1 GPa or less.

[0051] The residual stress Y in the third layer 5 can be determined by a method similar to the method for measuring the residual stress X in the second layer 4, except that the measurement is performed on the third layer 5. It has been confirmed that, as long as the measurement is performed using the same cutting tool 10, there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0052] <4th layer> <Composition of the 4th layer> The fourth layer 6 is made of TiN. Here, "made of TiN" means that in addition to TiN, inevitable impurities can be contained as long as the effect of the present disclosure is exhibited. Examples of the inevitable impurities include chlorine atoms (Cl). The total content of inevitable impurities in the fourth layer 6 may be more than 0 mass% or less than 3 mass%.

[0053] The fact that the fourth layer 6 is made of TiN is measured by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The content of inevitable impurities in the fourth layer 6 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that, as long as the measurements are performed using the same cutting tool 10, there is no variation in the measurement results even if the measurement points are arbitrarily selected.

[0054] <Fourth layer structure> The thickness of the fourth layer 6 may be 0.1 μm or more and 0.5 μm or less. This allows both superior chipping resistance and superior wear resistance to be achieved, and therefore a cutting tool having a longer tool life can be provided, particularly in the intermittent turning of cast iron. The thickness of the fourth layer 6 may be 0.2 μm or more and 0.4 μm or less.

[0055] <Other layers> Examples of the other layers include an underlayer (not shown), an intermediate layer (not shown), and a surface layer (not shown). The underlayer is a layer disposed between the substrate 1 and the third layer 5 when the third layer is present, and is a layer disposed between the substrate 1 and the first layer 3 when the third layer is not present. The surface layer is a layer located on the surface of the coating 2. The intermediate layer is a layer disposed between the third layer 5 and the first layer 3, between the first layer 3 and the second layer 4, or between the second layer 4 and the fourth layer 6. The intermediate layer is a thin adhesive layer such as TiCNO. Therefore, the intermediate layer does not affect the stress distribution.

[0056] [Embodiment 2: Manufacturing method of cutting tool] The method for manufacturing the cutting tool of this embodiment will be described with reference to Fig. 4. Fig. 4 is a schematic cross-sectional view of an example of a CVD apparatus used in manufacturing the cutting tool of this embodiment.

[0057] A method for manufacturing a cutting tool according to the present embodiment is the method for manufacturing the cutting tool according to the first embodiment, A first step of preparing a substrate; A second step of forming a coating on the substrate; and a third step of subjecting the coating to a blast treatment to obtain a cutting tool. The second step includes, in this order, a step 2A of forming a first layer by a CVD method and a step 2B of forming a second layer by a CVD method. The second step may further include a step 2C of forming a third layer by a CVD method before the step 2A. The second step may further include a step 2D of forming a fourth layer by a CVD method after the step 2B. Details of each step are described below.

[0058] ≪1st process≫ In the first step, a substrate is prepared. The substrate described in the first embodiment can be used.

[0059] For example, when a cemented carbide is used as the substrate, a commercially available substrate may be used, or the substrate may be manufactured by a general powder metallurgy method. When the substrate is manufactured by a general powder metallurgy method, for example, WC powder and Co powder are mixed by a ball mill or the like to obtain a mixed powder. The mixed powder is dried and then molded into a predetermined shape to obtain a molded body. The molded body is further sintered to obtain a WC-Co-based cemented carbide (sintered body). Next, the sintered body is subjected to a predetermined cutting edge processing such as honing, thereby manufacturing a substrate made of a WC-Co-based cemented carbide. Substrates other than those mentioned above can also be prepared as long as they are conventionally known as substrates of this type.

[0060] ≪Second process≫ In the second step, a coating is formed on the substrate to obtain a cutting tool. The coating is formed, for example, by using a CVD apparatus shown in FIG. 4. The CVD apparatus 30 includes a plurality of substrate setting jigs 31 for holding the substrate 1, and a reaction vessel 32 made of heat-resistant alloy steel that covers the substrate setting jigs 31. A temperature control device 33 for controlling the temperature inside the reaction vessel 32 is provided around the reaction vessel 32. The reaction vessel 32 is provided with a gas introduction pipe 35 having a gas introduction port 34. The gas introduction pipe 35 is arranged to extend vertically in the internal space of the reaction vessel 32 in which the substrate setting jigs 31 are arranged, and is arranged to be rotatable about the vertical axis, and is provided with a plurality of ejection holes (through holes 36) for ejecting gas into the reaction vessel 32. Using this CVD apparatus 30, the third layer, first layer, second layer, and fourth layer that constitute the coating can be formed as follows.

[0061] When the coating film includes the "other layer" described in embodiment 1, the "other layer" can be formed by a conventionally known method.

[0062] <2C process: process of forming the third layer by CVD method> In step 2C, the first layer is formed by the CVD method. More specifically, the substrate 1 is first placed in a substrate setting jig 31, and a source gas for the first layer is introduced into the reaction vessel 32 from a gas introduction pipe 35 while controlling the temperature and pressure in the reaction vessel 32 within a predetermined range. As a result, a third layer is formed on the substrate 1.

[0063] The source gas for the third layer is TiCl 4 , C.H. 3 C.N., C.O., N. 2 , HCl, and H 2 A mixture of the above gases is used.

[0064] TiCl in gas mixtures 4 The content of CH in the mixed gas may be 8.0% by volume or more and 9.0% by volume or less. 3The content of CN in the mixed gas may be 0.2% by volume or more and 1.0% by volume or less. The content of CO in the mixed gas may be 1.3% by volume or more and 2.0% by volume or less. 2 The content of HCl in the mixed gas may be 8.0 volume % or more and 12.0 volume % or less. The content of HCl in the mixed gas may be 1.0 volume % or more and 3.0 volume % or less.

[0065] The temperature inside the reaction vessel 32 may be controlled to be 800° C. or higher and 850° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 100 hPa or higher and 120 hPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0066] In the above-mentioned manufacturing method, the state of the third layer can be changed by controlling each condition of the CVD method. For example, the thickness of the third layer can be controlled by adjusting the film formation time.

[0067] <Step 2A: Step of forming the first layer by CVD method> In the 2A step, the first layer is formed by the CVD method. More specifically, when the 2D step is performed, the first cutting tool precursor on which the third layer is formed on the substrate is placed in the substrate setting jig 31, and the raw material gas for the first layer is introduced from the gas introduction pipe 35 into the reaction vessel 32 while controlling the temperature and pressure in the reaction vessel 32 to a predetermined range. This forms the first layer on the third layer. Alternatively, when the 2D step is not performed, the substrate 1 is placed in the substrate setting jig 31, and the raw material gas for the first layer is introduced from the gas introduction pipe 35 into the reaction vessel 32 while controlling the temperature and pressure in the reaction vessel 32 to a predetermined range. This forms the first layer on the substrate.

[0068] The source gas for the first layer was AlCl 3 , CO 2 , H 2 S, and H 2 A mixture of the above gases is used.

[0069] AlCl in gas mixtures 3The content of CO in the mixed gas may be 2.0% by volume or more and 2.5% by volume or less. 2 The content of H in the mixed gas may be 2.5% by volume or more and 3.5% by volume or less. 2 The content of S may be 0.5% by volume or more and 1.0% by volume or less.

[0070] The temperature inside the reaction vessel 32 may be controlled to be 980° C. or higher and 1015° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 60 hPa or higher and 75 hPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0071] In the above-mentioned manufacturing method, the state of the first layer can be changed by controlling each condition of the CVD method. For example, the thickness of the first layer can be controlled by adjusting the film formation time.

[0072] <Step 2B: Step of forming the second layer by CVD method> In step 2B, the second layer is formed by a CVD method. More specifically, the second cutting tool precursor having the first layer formed on the substrate is placed in a substrate setting jig 31, and a raw material gas for the second layer is introduced into the reaction vessel 32 from a gas introduction pipe 35 while controlling the temperature and pressure in the reaction vessel 32 within a predetermined range. This forms the second layer on the first layer.

[0073] The source gas for the second layer was TiCl 4 , C.H. 3 C.N., C.O., N. 2 , HCl, and H 2 A mixture of the above gases is used.

[0074] TiCl in gas mixtures 4 The content of CH in the mixed gas may be 8.0% by volume or more and 9.0% by volume or less. 3 The content of CN in the mixed gas may be 0.2% by volume or more and 0.8% by volume or less. The content of CO in the mixed gas may be 1.3% by volume or more and 2.0% by volume or less. 2The content of HCl in the mixed gas may be 8.0 volume % or more and 12.0 volume % or less. The content of HCl in the mixed gas may be 0.5 volume % or more and 2.0 volume % or less.

[0075] The temperature inside the reaction vessel 32 is controlled to be 850° C. or more and 950° C. or less, and the pressure inside the reaction vessel 32 is controlled to be 100 hPa or more and 110 hPa or less. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0076] In the above-mentioned manufacturing method, the state of the second layer can be changed by controlling each condition of the CVD method. For example, the thickness of the second layer can be controlled by adjusting the film formation time.

[0077] <2nd D process: Process of forming the 4th layer by CVD method> In the 2D step, the fourth layer is formed by a CVD method. More specifically, first, the third cutting tool precursor having the second layer formed on the first layer is placed in a substrate setting jig 31, and a source gas for the fourth layer is introduced into the reaction vessel 32 from a gas introduction pipe 35 while controlling the temperature and pressure in the reaction vessel 32 within a predetermined range. This forms the fourth layer on the second layer.

[0078] The source gas for the fourth layer is TiCl 4 , N 2 , HCl, and H 2 A mixture of the above gases is used.

[0079] TiCl in gas mixtures 4 The content of N in the mixed gas may be 3% by volume or more and 7% by volume or less. 2 The content of HCl in the mixed gas may be 20% by volume or more and 30% by volume or less. The content of HCl in the mixed gas may be 5% by volume or more and 10% by volume or less.

[0080] The temperature inside the reaction vessel 32 may be controlled to be 800° C. or higher and 1000° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 100 hPa or higher and 110 hPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0081] In the above-mentioned manufacturing method, the state of the fourth layer can be changed by controlling each condition of the CVD method. For example, the thickness of the fourth layer can be controlled by adjusting the film formation time.

[0082] <Third process: A process of obtaining a cutting tool by blasting the coating> In the third step, the coating is subjected to a blasting treatment to obtain a cutting tool. Here, "blasting" refers to a process in which a large number of small spheres (media) of steel or non-ferrous metal (e.g., ceramics) are collided (projected) at high speed onto the surface of the coating, such as the rake face, to change various properties of the surface, such as residual stress.

[0083] The types of media include, for example, ceramics, zirconia, alumina, and the like.

[0084] The average particle size of the media is greater than 15 μm and equal to or less than 30 μm.

[0085] The density of the projected media is between 100 g / min and 350 g / min.

[0086] The distance between the projection unit that projects the media and the surface of the coating (hereinafter also referred to as "projection distance") is 20 mm or more and less than 30 mm.

[0087] The projection angle of the media is 45° to the surface of the coating.

[0088] The pressure applied to the medium when projecting (hereinafter also referred to as "projection pressure") is 0.10 MPa or more and 0.50 MPa or less.

[0089] The blast processing time is from 20 seconds to 50 seconds.

[0090] The above-mentioned conditions for the blasting process can be appropriately adjusted in accordance with the configuration of the coating.

[0091] <Other processes> In the manufacturing method according to this embodiment, in addition to the steps described above, additional steps may be appropriately performed as long as the effects of this embodiment are not impaired.

[0092] <Features of the manufacturing method of the cutting tool according to this embodiment> The above manufacturing method in, 1. A cutting tool comprising a substrate and a coating disposed on the substrate, the coating including a first layer located on the substrate and a second layer located on the first layer, the first layer being α-Al 2 O 3 a cutting tool can be manufactured in which the second layer is made of TiCN, the thickness of the second layer is 0.5 μm or more and less than 2.0 μm, and the residual stress X of the second layer is −2.0 GPa or more and −0.5 GPa or less. The reason for this is presumably as follows.

[0093] The manufacturing method for a cutting tool of this embodiment is particularly characterized in that the second step includes steps 2A and 2B, and in step 2B, the film formation time is adjusted so that the thickness of the second layer is 0.5 μm or more and less than 2.0 μm, and in step 2B, the temperature in the reaction vessel 32 is controlled to be 850° C. or more and 950° C. or less, and the pressure in the reaction vessel 32 is controlled to be 100 hPa or more and 110 hPa or less, and in step 3, the average particle size of the media is more than 15 μm and 30 μm or less, the concentration of the projected media is 100 g / min or more and 350 g / min or less, the projection distance is 20 mm or more and less than 30 mm, the projection angle of the media is 45° with respect to the surface of the coating, the projection pressure is 0.10 MPa or more and 0.50 MPa or less, and the blast processing time is 20 seconds or more and 50 seconds or less. This makes it possible to suppress wear of the second layer caused by the blasting treatment and to effectively impart compressive residual stress to the second layer. This was newly discovered by the present inventors as a result of extensive investigations. EXAMPLES

[0094] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0095] <Cutting tool manufacturing> Cutting tools according to Samples 1 to 22 and 101 to 107 were produced in the following manner.

[0096] <1st process> As the substrate, a cemented carbide indexable cutting tip (shape: SEET13T3AGSN-G, manufactured by Sumitomo Electric Hardmetal Corp.) having a composition consisting of Co (6 mass%) and WC (balance) (but containing unavoidable impurities) was prepared.

[0097] <Second process> For each of Samples 19 to 22, 106, and 107, a third layer was formed on the substrate by CVD under the following conditions so that the composition of the third layer was as shown in Tables 5 and 6 (Step 2C). The deposition time was appropriately adjusted so that the third layer had a thickness as shown in Tables 5 and 6. (Conditions for 2C process) TiCl in gas mixtures 4 Content: 8.0-9.0% by volume CH in gas mixtures 3 CN content: 0.2-1.0% by volume CO content in mixed gas: 1.3-2.0% by volume N in gas mixtures 2 Content: 8.0-12.0% by volume HCl content in mixed gas: 1.0-3.0% by volume H in gas mixtures 2 Content: Remaining ·Temperature: 800~850℃ Pressure: 100~120hPa

[0098] Next, for each of Samples 19 to 22, Sample 106, and Sample 107, a first layer was formed on the third layer by CVD under the following conditions so that the composition of the first layer was as shown in Tables 3 and 4 (Step 2A). Also, for each of Samples 1 to 18 and Samples 101 to 105, a first layer was formed on the substrate by CVD under the following conditions so that the composition of the first layer was as shown in Tables 5 and 6 (Step 2A). The deposition time was appropriately adjusted so that the first layer had a thickness as shown in Tables 5 and 6. The H in the mixed gas was adjusted so that the orientation index TC (0 0 12) of the first layer had a value as shown in Tables 5 and 6. 2 The S content was appropriately adjusted within the following range. (Conditions for Step 2A) AlCl in gas mixtures 3 Content: 2.0-2.5% by volume CO in gas mixtures 2 Content: 2.5-3.5% by volume H in gas mixtures 2 S content: 0.5 to 1.0 volume% H in gas mixtures 2 Content: Remaining ·Temperature: 980~1015℃ Pressure: 60~75hPa

[0099] Next, for each of Samples 1 to 22, Samples 102 to 104, Sample 106, and Sample 107, a second layer was formed on the first layer by CVD under the following conditions so that the composition of the second layer was as shown in Tables 5 and 6 (Step 2B). The deposition time was appropriately adjusted so that the third layer had a thickness as shown in Tables 5 and 6. (Conditions for Step 2B) TiCl in gas mixtures 4 Content: 8.0-9.0% by volume CH in gas mixtures 3 CN content: 0.2-0.8% by volume CO content in mixed gas: 1.3-2.0% by volume N in gas mixtures 2 Content: 8.0-12.0% by volume HCl content in mixed gas: 0.5-2.0% by volume H in gas mixtures 2 Content: Remaining Temperature: as specified in Tables 1 and 2 Pressure: as specified in Tables 1 and 2

[0100] For sample 105, a second layer was formed on the first layer by a CVD method under the following conditions (step 2B) so that the composition of the second layer was as shown in Table 6. The deposition time was appropriately adjusted so that the second layer had a thickness as shown in Table 6. (Conditions for Step 2B) AlCl in gas mixtures 3 Content: 6.0% by volume NH in gas mixtures 3 Content: 1.5% by volume H in gas mixtures 2 Content: Remaining Temperature: As shown in Table 2 Pressure: as shown in Table 2

[0101] It should be noted that for sample 101, step 2B was not performed.

[0102] As described above, for each of Samples 1 to 22 and Samples 101 to 107, a coating was formed on the substrate.

[0103] <3rd process> The surface of the coating was subjected to a blasting treatment under the conditions shown in Tables 3 and 4.

[0104] By the above procedure, cutting tools according to Samples 1 to 22 and 101 to 107 were produced.

[0105] [Table 1]

[0106] [Table 2]

[0107] [Table 3]

[0108] [Table 4]

[0109] [Table 5]

[0110] [Table 6]

[0111] <Cutting tool characteristic evaluation> <Composition of the first layer> The composition of the first layer of each sample cutting tool was determined by the method described in embodiment 1. The results are shown in the "Composition" column of the "First Layer" column in Tables 5 and 6. In the "Composition" column of the "First Layer" column in Tables 5 and 6, "α-Al 2 O 3 ", the first layer is α-Al 2 O 3 This means that it consists of:

[0112] <First layer orientation index TC(0 0 12)> For the cutting tools according to each sample, the orientation index TC(0 0 12) of the first layer was determined by the method described in embodiment 1. The results are shown in the "TC(0 0 12)" column of the "First Layer" column in Tables 5 and 6.

[0113] <Composition of the second layer> The composition of the second layer of each sample cutting tool was determined by the method described in embodiment 1. The results are shown in the "Composition" column of the "Second Layer" column in Tables 5 and 6. When "TiCN" is written in the "Composition" column of the "Second Layer" column in Tables 5 and 6, it means that the second layer is made of TiCN.

[0114] <Residual stress X of the second layer> For each sample cutting tool, the residual stress X of the second layer was determined by the method described in embodiment 1. The results are shown in the "X [GPa]" column of Tables 5 and 6.

[0115] <Composition of the third layer> For each sample cutting tool, the composition of the third layer was determined by the method described in embodiment 1. The results are shown in the "Composition" column of the "Third Layer" column in Tables 5 and 6. When "TiCN" is written in the "Composition" column of the "Third Layer" column in Tables 5 and 6, it means that the third layer is made of TiCN.

[0116] <Residual stress Y of the third layer> For each sample cutting tool, the residual stress Y of the third layer was determined by the method described in embodiment 1. The results are shown in the "Y [GPa]" column of Tables 5 and 6.

[0117] <Coating thickness> The thickness of the coating of each sample cutting tool was determined by the method described in embodiment 1. The results are shown in the "Thickness [μm]" column of the "Coating" column in Tables 5 and 6.

[0118] <Cutting test> Cutting tests were performed using the cutting tools of each sample under the following cutting conditions. The time when the damage progressed due to a combination of wear and chipping and the maximum flank wear amount Vbmax [mm] of the ridge line portion of the cutting tool exceeded 0.3 mm was measured as the tool life. The results are shown in the "Tool life [min]" column of Tables 5 and 6. (Cutting conditions) Work material: FCD450 (grooved round bar) Processing: Grooved round bar external diameter turning Cutting speed: 250m / min Feed rate: 0.2mm / rev Cutting fluid: Water-soluble cutting oil The above cutting conditions correspond to those for interrupted turning of cast iron.

[0119] The cutting tools of Samples 1 to 22 correspond to Examples. The cutting tools of Samples 101 to 107 correspond to Comparative Examples. From the results in Tables 5 and 6, it was found that the cutting tools of Samples 1 to 22 have a longer tool life than the cutting tools of Samples 101 to 107, even in the intermittent turning of cast iron.

[0120] From the above, it was found that the cutting tools of Samples 1 to 22 had a long tool life even in the intermittent turning of cast iron.

[0121] Although the embodiments and examples of the present disclosure have been described above, it is intended from the outset that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways.

[0122] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the embodiments and examples described above, and is intended to include the meaning equivalent to the claims and all modifications within the scope. [Explanation of symbols]

[0123] REFERENCE SIGNS LIST 1 substrate, 2 coating, 3 first layer, 4 second layer, 5 third layer, 6 fourth layer, 10 cutting tool, 30 CVD apparatus, 31 substrate setting jig, 32 reaction vessel, 33 temperature control apparatus, 34 gas inlet, 35 gas inlet pipe, 36 through hole.

Claims

1. 1. A cutting tool comprising a substrate and a coating disposed on the substrate, the coating includes a first layer disposed on the substrate and a second layer disposed on the first layer; The first layer is α-Al ２ O ３ It consists of the second layer is made of TiCN; the thickness of the second layer is 0.5 μm or more and less than 2.0 μm; The second layer has a residual stress X of −2.0 GPa or more and −0.5 GPa or less.

2. The cutting tool according to claim 1 , wherein the first layer has a thickness of 3.0 μm or more and 15.0 μm or less.

3. The cutting tool according to claim 1 or 2, wherein the orientation index TC(0 0 12) of the first layer is 3.0 or more.

4. the coating further includes a third layer positioned between the substrate and the first layer; the third layer is made of TiCN, 3. The cutting tool according to claim 1, wherein the residual stress Y of the third layer is −1.0 GPa or more and 1.0 GPa or less.

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