KR102719440B1 - Cutting tools with hard coating - Google Patents

Abstract

The present invention aims to provide a cutting tool having a hard film having excellent wear resistance and chipping resistance. To achieve the above objects, the cutting tool according to the present invention includes a hard base material and a first film formed on the hard base material and having a composition of Ti _(1-x) Si _x N (0.05<x≤0.30), wherein the first film can satisfy 0.5<F _Si /(F Si + R _Si )≤0.6, where the atomic Si content in a flank surface within 500 ㎛ from an edge center is F _Si and the atomic Si content in a rake surface within 500 _㎛ from the edge center is R _Si .

Description

CUTTING TOOLS WITH HARD COATING

The present invention relates to a hard film formed on a hard base material such as a superalloy, a cermet, a ceramic, or cubic boron nitride used in a cutting tool, and more particularly, to a hard film including a hard film composed of Ti _(1-x) Si _x N on the upper portion, and in which the Si content of the hard film is distributed differently depending on the portion.

In tools for processing high-hardness workpieces with a hardness of HRC 50 or higher, such as high-hardness steel, a technology of a hard film made of various ceramics on a hard base such as a cemented carbide, cermet, end mill, or drill is being adopted to improve cutting performance and extend tool life.

Among the hard films, the composite nitride film of Ti and Si in particular has excellent wear resistance and heat resistance, so that it can exhibit excellent durability in the cutting processing of high-hardness steels. However, in such Ti _(1-x) Si _x N hard films, when the Si content is high, the wear resistance is excellent but the chipping resistance is low, and conversely, when the Si content is low, the wear resistance is low and the chipping resistance is improved.

To solve the problem of these conflicting characteristics, conventional technologies have used a film composed of a composite that additionally composites Al, etc., in addition to Ti and Si. However, although this may improve chipping resistance compared to a Ti _(1-x) Si _x N layer, it has the problem of lower wear resistance compared to pure Ti _(1-x) Si _x N.

Japanese Patent Publication No. 6155940

The purpose of the present invention is to provide a cutting tool having a hard film having excellent wear resistance and chipping resistance.

To achieve the above purpose, a cutting tool according to the present invention includes a hard base material and a first film formed on the hard base material and having a composition of Ti _(1-x) Si _x N (0.05<x≤0.30), wherein the first film can satisfy 0.5<F _Si /(F Si + R _Si )≤0.6, where the atomic Si content in a flank surface within 500 ㎛ from an edge center is F _Si and the atomic Si content in a rake surface within 500 _㎛ from the edge center is R _Si .

In addition, when the content of Si on an atomic basis at a portion more than 2 mm away from the edge in the first film is referred to as C _Si , the relationship between the content of Si on an atomic basis at a flank surface within 500 μm from the edge center and F _Si can further satisfy 0.7≤F _Si /C _Si ≤0.9.

In addition, the cutting tool according to the present invention further includes a second film between the hard base material and the first film, and the second film has a composition of Al _(1-abc) Ti _a Cr _b Me _c N (Me is any one of B, Si, Zr, V, Mn, Nb, Mo, Ta, and W, and 0<(1-abc), 0.1≤a≤0.6, 0≤b≤0.5, 0≤c≤0.15), and may necessarily include at least one of Ti and Cr.

Additionally, in the cutting tool according to the present invention, the thickness of the first film may be in the range of 0.5 to 3 μm, and the thickness of the second film may be in the range of 1 to 6 μm.

In addition, in the cutting tool according to the present invention, a dispersed metal phase exists on the hard base material side of the second film, and the metal phase may have a metal element included in the composition of the second film of 60 atomic% or more.

According to the present invention, a cutting tool having a hard film formed that can satisfy the characteristics required for each part can be provided, thereby improving the wear resistance characteristics and service life of the cutting tool. In addition, a cutting tool having a hard film that is excellent in wear resistance and excellent in chipping resistance can be provided.

FIG. 1 is a schematic diagram illustrating a cutting tool having first and second films formed on a hard base material according to one embodiment of the present invention.
FIG. 2 is a scanning electron microscope image of a cross-section of a second film in one embodiment according to the present invention.

Hereinafter, in describing the present invention, if it is judged that a specific description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, when a part is said to 'include' a certain component, this does not mean that other components are excluded, but rather that other components can be included, unless specifically stated otherwise.

A cutting tool according to the present invention comprises a hard base material and a first film having a composition of Ti _(1-x) Si _x N (0.05<x≤0.30) formed on the hard base material, wherein the first film can satisfy 0.5<F _Si /(F _Si +R _Si )≤0.6, where the atomic Si content in a flank surface within 500 ㎛ from an edge center is F _Si and the atomic Si content in a rake surface within 500 ㎛ from the edge center is R _Si .

In order to improve the wear resistance and life of cutting tools, a hard film formed on a hard substrate has not only wear resistance but also chipping resistance as important required characteristics. This is because if the chipping resistance decreases, the life of the cutting tool will eventually decrease. In the present invention, the Ti _(1-x) Si _x N layer formed as an upper film has conflicting characteristics of wear resistance and chipping resistance depending on the Si content, and many attempts have been made to achieve harmony at an appropriate content.

However, these wear resistance and chipping resistance may be more important characteristics depending on the part of the cutting tool. Wear resistance is more important on the flank surface of the cutting tool, whereas heat resistance and chipping resistance are more important on the rake surface. Therefore, if the Si content is adjusted to the required characteristics of the flank surface, the wear resistance is excellent, but the heat resistance and chipping resistance on the rake surface are poor, which adversely affects the life of the tool. Conversely, if the Si content is adjusted to the rake surface, where heat resistance and chipping resistance are important, the wear resistance on the flank surface is poor, which reduces the cutting performance of the tool and also worsens the life of the tool.

In order to solve these problems, the present invention makes it possible to satisfy the different characteristics required for each part of the cutting tool by making the Si contents of the flank face and the rake face different from each other, thereby increasing the cutting performance and life of the tool. To this end, the composition ratio of Si in the first film is in the range of 0.05<x≤0.30, which can achieve a certain degree of harmony between wear resistance and chipping resistance, and at the same time, the Si content of the flank face, where wear resistance is more important, is made higher than the Si content of the rake face, where chipping resistance is more important, so that the different characteristics required for each part of the cutting tool can be satisfied together. On the other hand, if the difference in the Si content between the flank face and the rake face is too large, the balance between wear resistance and chipping resistance will be broken, which may have a negative effect on the life of the cutting tool. Therefore, when the atomic% of Si in the flank face is F _Si and the atomic% of Si in the rake face is R _Si , it is preferable that 0.5＜F _Si /(F _Si + R _Si )≤0.6 is satisfied.

The ranges in which the flank and rake faces have different Si compositions are within 500 μm from the center of the cutting edge. This is because this area is likely to come into contact with the workpiece in actual machining and is a part that requires particularly fine control of characteristics.

Meanwhile, it is also necessary to control the Si content between the part near the center of the first film and the part far from the center of the cutting edge. The near part is particularly important for chipping resistance due to friction with the cutting material. Therefore, it is desirable to have a lower Si content than that far from the cutting edge.

To this end, in the present invention, when the content of Si on an atomic basis at a portion more than 2 mm away from the edge in the first film is referred to as C _Si , the relationship between the content of Si on an atomic basis at a flank surface within 500 μm from the edge center and F _Si can further satisfy 0.7≤F _Si /C _Si ≤0.9.

If the content of F _Si is smaller than the above ratio, the wear resistance in the area near the cutting edge is too low, and if it is larger than the above ratio, there is no improvement in chipping resistance, so the above range is preferable, and more preferably, it is in the range of 0.7 to 0.8.

In addition, the cutting tool provided in the present invention further includes a second film between the hard base material and the first film, and the second film has a composition of Al _(1-abc) Ti _a Cr _b Me _c N (Me is any one of B, Si, Zr, V, Mn, Nb, Mo, Ta, and W, and (1-abc)>0, 1≤a≤0.6, 0≤b≤0.5, 0≤c≤0.15), and necessarily includes at least one of Ti and Cr.

A nitride thin film containing Al and Ti or Cr is known to have excellent wear resistance as well as heat resistance and chipping resistance. By arranging a second film of this composition between a hard base material and a first film of Ti _(1-x) Si _x N composition having excellent wear resistance, the chipping resistance of the first film, which has excellent wear resistance but relatively poor chipping resistance, can be supplemented.

The second film may have, in addition to Al, Ti, and Cr, any one metal element selected from B, Si, Zr, V, Mn, Nb, Mo, Ta, and W. By controlling these metal elements, the wear resistance, chipping resistance, heat resistance, etc. of the second film can be significantly improved.

In the second film, a, b, and c determine the composition ratio of the metal elements Al, Ti, Cr, and Me. When the composition of Al is high, the wear resistance, oxidation resistance, and lubrication are better, but when the Al content is too high, there is a problem of increased chipping, so it is preferable that the contents of Ti and Cr be 0≤a≤0.6 and 0≤b≤0.5.

Other elements can improve the chipping resistance, heat resistance, wear resistance, etc. of the second film by adding Zr, B, etc., but if the content is high, it can act as a cause of increased residual stress due to an increase in the amorphous phase. Therefore, it is preferable that the content of Me, an other element, be 0 to 0.15.

The thickness of the first film described in the present invention may be in the range of 0.5 to 3 μm, and the thickness of the second film may be in the range of 1 to 6 μm.

The first film, which is formed on the upper layer and has a large function of providing wear resistance, is difficult to provide sufficient wear resistance when it is less than 0.5 ㎛, and there is a concern that internal stress may increase when it exceeds 3 ㎛.

Meanwhile, it is difficult for the second film to sufficiently supplement wear resistance when it is less than 1㎛, and when it exceeds 6㎛, the internal stress increases, which may actually increase chipping.

In addition, in the present invention, a dispersed metal phase exists on the hard base material side of the second film, and the metal phase may have a metal element content of 60 atomic% or more in the composition of the lower film.

In forming the second film, the bonding strength between the second film and the hard base material can be improved by forming a metal phase dispersed in an island shape on the contact surface with the hard base material. The dispersed metal phase can be a metal phase in which a metal element included in the composition of the second film is 60 atomic% or more.

These metal phases can strengthen the bonding strength between the second film and the hard base material by providing an anchoring effect to the second film, and consequently strengthen the bonding strength of the entire hard film including the first film and the second film to the base material.

A schematic diagram of a cutting tool according to the present invention is shown in Fig. 1. A second film (30) is formed on a hard base material (10), and a first film (20) is formed thereon. In the first film (20), the Si content (F _si ) in the flank surface portion (21) within a range of 500 μm from the cutting edge center (24) and the Si content (R _si ) in the rake surface portion (22) are different from each other, so that they are in the range of 0.5＜F _Si /(F _Si +R _Si )≤0.6.

In addition, the ratio of the Si content (F _Si ) in the flank surface portion (21) close to the cutting edge to the Si content (C _Si ) in the portion (23) far from the cutting edge, F _Si /C _Si , is in the range of 0.7 to 0.9.

Meanwhile, in the second film, a metal phase (31) dispersed on the hard base material side can be formed.

Hereinafter, in order to explain the present invention more specifically, preferred embodiments according to the present invention will be described in more detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein.

[Example]

In an embodiment of the present invention, a hard film composed of a second film and a first film was formed as shown in Fig. 1 by using two types of surface treatments (ion bombardment) and an arc ion plating method, which is a physical vapor deposition (PVD) method, on the surface of a base material made of a superalloy.

Specifically, the targets used for coating were arc targets of Ti, Cr, TiAl, AlCr, and TiSiN, and the base materials were subjected to wet microblasting and washed with ultrapure water, and then dried, and mounted along the circumference at a predetermined distance in the radial direction from the central axis of the rotary table in the coating furnace, and the initial vacuum pressure in the coating furnace was reduced to 8.5×10 ^-5 Torr or less.

After heating the temperature to 400 to 600°C, the base material was rotated on the rotary table in an Ar gas atmosphere by applying a bias voltage of -400 to -200 V under an Ar gas atmosphere for 30 to 90 minutes to perform Ar ion bombardment. Thereafter, a bias voltage of -1000 to -600 V was applied, and an arc current of 70 to 150 A was supplied to the arc target (one of Ti and Cr) to perform metal (including semi-metal) ion bombardment for 1 to 20 minutes. The metal ion bombardment may be performed before performing the Ar ion bombardment. The gas pressure for coating was maintained at 50 mTorr or less, preferably 40 mTorr or less, to form the second film as the lower layer and the first film as the upper layer.

The second film was formed using TiAl, AlCr, and TiSi targets under the conditions of a bias voltage of -100 to -30 V, an arc current of 100 to 150 A, and a pressure of 20 to 40 mtorr using _N2 as a reaction gas.

The above first film was formed using a TiSi target by applying a pulsed bias voltage of -150 to -50 V and also using a duty cycle of 50 to 90% and a frequency in the range of 20 to 40 kHz.

The examples and comparative examples of the present invention were manufactured under the above conditions, and basic information on the conditions and thickness of the corresponding hard film is shown in Table 1 below. The coating conditions may vary depending on the equipment characteristics and conditions.

division Second layer First layer Target 1
(Composition ratio) Target 2
(Composition ratio) thickness
(um) Target
(Composition ratio) bias thickness
(um) Frequency
(kHz) Duty cycle
(%) voltage
(V) Example 1 TiAl
(50:50) - 3.2 TiSi
(80:20) 30 80 -70 1.5 Example 2 TiAl(50:50) - 3.5 TiSi
(85:15) 30 75 -100 1.2 Example 3 TiAl(50:50) - 4.0 TiSi
(90:10) 30 70 -120 0.8 Example 4 TiAl(50:50) AlCr
(70:30) 3.5 TiSi
(75:25) 30 80 -50 1.8 Example 5 TiAl(50:50) AlCr
(70:30) 3.6 TiSi
(80:20) 30 80 -70 1.6 Example 6 TiAl(50:50) AlCr
(70:30) 3.8 TiSi
(85:15) 25 70 -100 1.1 Example 7 AlCr(70:30) - 3.0 TiSi
(75:25) 30 70 -90 1.4 Example 8 AlCr(70:30) - 2.9 TiSi
(80:20) 25 65 -120 1.5 Example 9 AlCr(70:30) TiSi
(90:10) 2.5 TiSi
(90:10) 20 60 -150 1.2 Example 10 AlCr(70:30) TiSi
(90:10) 2.8 TiSi
(90:10) 25 65 -130 1.5 Comparative Example 1 TiAl(50:50) - 3.3 TiSi
(80:20) - - -70 1.2 Comparative Example 2 TiAl(50:50) - 3.6 TiSi
(85:15) - - -100 1.0 Comparative Example 3 TiAl(50:50) - 3.9 TiSi
(90:10) - - -120 0.7 Comparative Example 4 TiAl(50:50) AlCr
(70:30) 3.5 TiSi
(75:25) - - -50 1.6 Comparative Example 5 TiAl(50:50) AlCr
(70:30) 3.8 TiSi
(80:20) - - -70 1.6 Comparative Example 6 TiAl(50:50) AlCr
(70:30) 3.6 TiSi
(85:15) - - -100 1.0 Comparative Example 7 AlCr(70:30) - 3.0 TiSi
(75:25) - - -90 1.2 Comparative Example 8 AlCr(70:30) - 3.0 TiSi
(80:20) - - -120 1.4 Comparative Example 9 AlCr(70:30) TiSi
(90:10) 2.6 TiSi
(90:10) - - -150 1.0 Comparative Example 10 AlCr(70:30) TiSi
(90:10) 2.8 TiSi
(90:10) - - -130 1.3

The Si content by part was measured for the samples made according to the conditions of Table 1. The cross-sections of the hard films of the examples and comparative examples according to Table 1 were analyzed with a SEM (Scanning Electron Microscope) at a magnification of 15,000 times, and the compositions were analyzed with an EDS (Energy Dispersive Spectrometer). The results when the Si content on an atomic basis in the flank plane within 500 μm is F _Si , the Si content on an atomic basis in the rake plane within 500 μm from the edge center is R _Si , and the Si content other than 2 mm from the edge center is C _Si are shown in Table 2 below. (The Si content at this time is the content excluding non-metals.)

division F _Si
(at.%) R _Si
(at.%) C _Si
(at.%) F _Si /(F _Si +R _Si ) F _Si /C _Si Example 1 16.0 14.8 19.4 0.519 0.82 Example 2 11.7 11.1 15.1 0.513 0.77 Example 3 7.6 6.9 10.3 0.524 0.74 Example 4 21.3 21.0 24.9 0.503 0.86 Example 5 16.2 14.4 19.8 0.529 0.82 Example 6 11.7 9.8 15.0 0.544 0.78 Example 7 20.0 17.5 25.1 0.533 0.80 Example 8 15.0 13.6 20.7 0.524 0.72 Example 9 7.2 5.4 10.5 0.571 0.69 Example 10 7.6 6.2 10.3 0.551 0.74 Comparative Example 1 15.0 15.3 20.8 0.495 0.72 Comparative Example 2 10.4 10.0 15.1 0.509 0.69 Comparative Example 3 6.7 6.0 10.4 0.528 0.64 Comparative Example 4 20.8 20.8 24.3 0.499 0.85 Comparative Example 5 15.4 16.0 19.7 0.490 0.78 Comparative Example 6 10.4 10.2 15.3 0.504 0.68 Comparative Example 7 18.0 18.4 25.0 0.495 0.72 Comparative Example 8 13.4 13.1 19.9 0.506 0.67 Comparative Example 9 6.0 5.7 10.2 0.513 0.59 Comparative Example 10 6.2 6.3 10.3 0.496 0.60

In the case of the example, the analysis results using EDS confirmed that the Si content of the first film satisfied 0.5＜F _Si /(F _Si +R _Si )≤0.6 and 0.7≤F _Si /C _Si ≤0.9, and the wear resistance and chipping resistance of the hard film formed in this way were evaluated under the following conditions.

(1) 2-blade ball end mill machining

Workpiece material: Heat treated SKD11 (diameter: 300mm*200mm*100mm)

Workpiece hardness: HRC60~63

Sample Model Number: PBE2080-100

RPM: 5570 rpm

Cutting feed: 0.12 mm/tooth

Cutting depth (axial): 0.4mm

Cutting depth (radial): 0.5mm

Cutting oil: Unused

(2) 2-blade ball end mill machining

Workpiece material: Heat treated SKD61 (diameter: 300mm*200mm*100mm)

Workpiece hardness: HRC50~55

Sample Model Number: PBE2100-100

RPM: 6685 rpm

Cutting feed: 0.14 mm/tooth

Cutting depth (axial): 0.6mm

Cutting depth (radial): 0.6mm

Cutting oil: Unused

The processing results evaluated under the two conditions described above are shown in Table 3 below.

division Heat treatment SKD11 processing results Heat treatment SKD61 processing results Processing length
(mm) Wear type Processing length
(mm) Wear type Example 1 102 Wear/chipping 550 Wear/chipping Example 2 102 Wear/chipping 560 Wear/chipping Example 3 96 Wear/chipping 590 Wear/chipping Example 4 96 Wear/chipping 530 Wear/chipping Example 5 120 Wear/chipping 580 Wear/chipping Example 6 114 Wear/chipping 590 Wear/chipping Example 7 84 Wear/chipping 550 Wear/chipping Example 8 90 Wear/chipping 580 Wear/chipping Example 9 96 Wear/chipping 600 Wear/chipping Example 10 90 Wear/chipping 620 Wear/chipping Comparative Example 1 42 Chipping/Brokenness 430 Wear/chipping Comparative Example 2 30 Chipping/Brokenness 450 Wear/chipping Comparative Example 3 30 Chipping/Brokenness 500 Wear/chipping Comparative Example 4 42 Chipping/Brokenness 580 Wear/chipping Comparative Example 5 60 Chipping/Brokenness 480 Wear/chipping Comparative Example 6 54 Chipping/Brokenness 380 Wear/chipping Comparative Example 7 36 Chipping/Brokenness 450 Wear/chipping Comparative Example 8 30 Chipping/Brokenness 400 Wear/chipping Comparative Example 9 24 Chipping/Brokenness 300 Wear/chipping Comparative Example 10 42 Chipping/Brokenness 350 Wear/chipping

As shown in the cutting performance evaluation results above, Examples 1 to 10 showed better tool life than Comparative Examples 1 to 10. In particular, as the SKD11 machining length increased significantly, the SKD61 machining length also showed improved results. Through this, it was confirmed that the tool life was improved by supplementing the wear resistance and chipping resistance through the difference in Si content between the flank surface and the rake surface.

In addition, in the case of the present invention, a metal phase as in Fig. 2 can be confirmed by a surface treatment process (ion bombardment ) prior to coating, and the conditions of examples and comparative examples for this are shown in Table 4 below.

division Ion Bombardment Second layer First layer Ar metal Target
(Composition ratio) thickness
(um) Target
(Composition ratio) bias thickness
(um) hour
(min) Target hour
(min) Frequency
(kHz) Duty
Cycle
(%) voltage
(V) Example 11 60 Ti 15 TiAl
(50:50) 3.2 TiSi
(80:20) 30 80 -70 1.2 Example 12 60 Cr 10 AlCr(70:30) 3.0 TiSi
(80:20) 30 80 -70 1.3 Comparative Example 11 - - - TiAl(50:50) 3.1 TiSi
(80:20) 30 80 -70 1.2 Comparative Example 12 60 - - TiAl(50:50) 3.2 TiSi
(80:20) 30 80 -70 1.1 Comparative Example 13 60 - - AlCr(70:30) 3.0 TiSi
(80:20) 30 80 -70 1.2

The cross-sections of the hard films of the examples and comparative examples of the present invention were analyzed at a magnification of 15,000 times using SEM to confirm the presence or absence of metal structure, and the results of the EDS composition analysis are shown in Table 5 below.

division Presence or absence of metal structure EDS composition analysis results of metal structure [at.%] Ti Al Cr Co W N Example 11 There is 82.36 5.40 - 5.10 5.47 1.67 Example 12 There is - 13.65 72.68 5.13 5.78 2.76 Comparative Example 11 doesn't exist - - - - - - Comparative Example 12 doesn't exist - - - - - - Comparative Example 13 doesn't exist - - - - - -

In the case of the above-described embodiment of the present invention, it was confirmed as a result of EDS analysis that there was a metal structure having a value containing 60 at% or more of the arc target element used in the metal ion bombardment, and the peeling resistance of the hard film formed in this manner was evaluated under the following conditions.

(3) 2-blade ball end mill machining

Workpiece material: STAVAX (diameter: 300mm*200mm*100mm)

Hardness of workpiece: HRC48~50

Sample Model Number: PBE2100-100

RPM: 4775 rpm

Cutting feed: 0.15 mm/tooth

Cutting depth (axial): 0.6mm

Cutting depth (radial): 0.6mm

Cutting oil: Use

The processing results evaluated under the conditions described above are shown in Table 6 below.

division STAVAX processing results Processing length
(mm) Wear type Example 11 600 normal wear Example 12 680 normal wear Comparative Example 11 320 Film tearing/wear/damage Comparative Example 12 520 Lakeside film tearing/wear/damage Comparative Example 13 550 Lakeside film tearing/wear/damage

As shown in the cutting performance evaluation results above, Examples 11 to 12 showed better tool life than Comparative Examples 11 to 13. In particular, the tearing phenomenon of the rake surface was reduced, and the tool life ended due to normal wear. Through this, it can be confirmed that the peeling resistance was improved through surface treatment before coating.

Claims (5)

Hard substrate; and
A first film having a composition of Ti _(1-x) Si _x N (0.05<x≤0.30) formed on the above hard base material,
A cutting tool, wherein the first film satisfies 0.5＜F _Si /(F Si +R _Si )≤0.6, where the atomic Si content in the flank surface within 500 ㎛ from the edge center is F _Si and the atomic Si content in the rake surface within 500 ㎛ from the edge center is R _Si , _and is formed through an arc ion plating method. In the first paragraph
A cutting tool, wherein when the content of Si on an atomic basis at a portion located 2 mm or more away from the edge in the first film is C _Si , the relationship between the content of Si on an atomic basis at a flank surface within 500 ㎛ from the edge center and F _Si further satisfies 0.7≤F _Si /C _Si ≤0.9. In paragraph 1,
Further comprising a second film between the hard base material and the first film,
A cutting tool wherein the second film has a composition of Al _(1-abc) Ti _a Cr _b Me _c N (Me is any one of B, Si, Zr, V, Mn, Nb, Mo, Ta, and W, and 0<(1-abc), 0.1≤a≤0.6, 0≤b≤0.5, 0≤c≤0.15), and necessarily contains at least one of Ti and Cr. In the third paragraph,
A cutting tool, wherein the thickness of the first film is in the range of 0.5 to 3 μm, and the thickness of the second film is in the range of 1 to 6 μm. In the third paragraph,
A cutting tool, wherein a dispersed metal phase exists on the hard base material side of the second film, and the metal phase contains 60 atomic% or more of a metal element included in the composition of the second film.

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