Coated cutting tool and cutting tool

Abstract

The coated cutting tool of the present invention has a substrate and a coating disposed on the substrate. The coating comprises crystals having a cubic crystal structure. The coating has a striped structure when observed in cross-section using a transmission electron microscope. The striped structure has two layers arranged alternately in the thickness direction. The two layers contain Si and at least one metal element. The content of the metal element in the two layers is different from that in the other layer. Each of the two layers comprises crystals having a cubic crystal structure. When the lattice constant of the cubic crystal structure contained in one of the two layers is taken as the first lattice constant, and the lattice constant of the cubic crystal structure contained in the other of the two layers is taken as the second lattice constant, the difference between the magnitude of the first lattice constant and the magnitude of the second lattice constant is greater than 0% and less than 0.1%.

Description

Technical Field

[0001] This invention relates to coated cutting tools and cutting tools. Background Technology

[0002] As cutting tools used in cutting processes such as turning and hobbing, coated tools are known to have coatings applied to the surface of substrates such as cemented carbide, cermet, and ceramic, thereby improving their wear resistance and other properties.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-146777 Summary of the Invention

[0006] One aspect of the coated cutting tool of the present invention has a substrate and a coating disposed on the substrate. The coating comprises crystals having a cubic crystal structure. The coating has a striped structure when viewed in cross-section using a transmission electron microscope. The striped structure has two layers arranged alternately in the thickness direction. The two layers contain Si and at least one metal element. The content of the metal element in the two layers is different from that in the other layer. Each of the two layers comprises crystals having a cubic crystal structure. When the lattice constant of the cubic crystal structure contained in one of the two layers is taken as the first lattice constant, and the lattice constant of the cubic crystal structure contained in the other of the two layers is taken as the second lattice constant, the difference between the magnitude of the first lattice constant and the magnitude of the second lattice constant is greater than 0% and less than 0.1%. Attached Figure Description

[0007] Figure 1 This is a perspective view showing an example of a coated cutting tool according to an embodiment.

[0008] Figure 2 This is a side sectional view showing an example of a coated cutting tool according to an embodiment.

[0009] Figure 3 This is a cross-sectional view showing an example of the coating in an embodiment.

[0010] Figure 4 yes Figure 3 An enlarged schematic diagram of section H is shown.

[0011] Figure 5 This is a schematic diagram used to illustrate the Al, Cr, and Si contents of the first and second layers.

[0012] Figure 6 This is a front view showing an example of a cutting tool used in an embodiment.

[0013] Figure 7This is a table showing the measurement results of the coating composition and lattice constant of samples No.1 to No.6. Detailed Implementation

[0014] Hereinafter, with reference to the accompanying drawings, a detailed description will be provided of the methods (hereinafter referred to as "embodiments") for implementing the coated cutting tools and cutting tools of the present invention. However, the coated cutting tools and cutting tools of the present invention are not limited to this embodiment. Furthermore, the various embodiments can be suitably combined without departing from the scope of the processing. In addition, in the following embodiments, the same reference numerals are used for the same parts, and repeated descriptions are omitted.

[0015] Furthermore, in the embodiments shown below, expressions such as "certain," "orthogonal," "perpendicular," or "parallel" are used, but these expressions do not need to be "certain," "orthogonal," "perpendicular," or "parallel" in a strict sense. That is, the above expressions allow for deviations in manufacturing precision, setting precision, etc.

[0016] There is room for further improvement in terms of thermal stability in the aforementioned prior art.

[0017] Coated Cutting Tools

[0018] Figure 1 This is a perspective view illustrating an example of a coated cutting tool according to an embodiment. Additionally, Figure 2 This is a side sectional view showing an example of the coated cutting tool 1 according to the embodiment. (e.g.) Figure 1 As shown, the coated cutting tool 1 of the embodiment has a blade body 2.

[0019] (Blade Body 2)

[0020] Blade body 2, for example, has an upper surface and a lower surface (with) Figure 1 The shape of the surfaces intersecting the Z-axis shown is a parallelogram-shaped hexahedron.

[0021] One corner of the blade body 2 functions as a cutting edge. The cutting edge has a first surface (e.g., an upper surface) and a second surface (e.g., a side surface) connected to the first surface. In this embodiment, the first surface functions as a "front face" to scrape away chips generated by cutting, and the second surface functions as a "back face." The cutting edge is located on at least a portion of the edge where the first and second surfaces intersect, and the coated tool 1 cuts the workpiece by bringing this cutting edge into contact with the workpiece.

[0022] A through hole 5 is provided in the center of the blade body 2, extending vertically through the blade body 2. A bolt 75 for mounting the coated tool 1 on the tool holder 70 (described later) is inserted into the through hole 5. Figure 6 ).

[0023] like Figure 2 As shown, the blade body 2 has a substrate 10 and a coating 20.

[0024] (Matrix 10)

[0025] The matrix 10 is formed, for example, of a cemented carbide. The cemented carbide contains W (tungsten), specifically WC (tungsten carbide). Alternatively, the cemented carbide may also contain Ni (nickel) and Co (cobalt). Specifically, the matrix 10 is formed of a WC-based cemented carbide with WC-containing hard particles as the hard phase component and Co as the main component of the binder phase.

[0026] Alternatively, the matrix 10 can also be formed of cermet. Cermet, for example, contains Ti (titanium), specifically TiC (titanium carbide) or TiN (titanium nitride). Additionally, cermet can also contain Ni and Co.

[0027] Alternatively, the matrix 10 may also be formed from a cubic boron nitride sintered body containing cubic boron nitride (cBN) particles. The matrix 10 is not limited to cubic boron nitride (cBN) particles, but may also contain hexagonal boron nitride (hBN), rhombohedral boron nitride (rBN), wurtzite boron nitride (wBN), and other particles.

[0028] (Coating 20)

[0029] Coating 20, for example, is applied to the substrate 10 to improve its wear resistance, heat resistance, etc. Figure 2 In this example, coating 20 completely covers the substrate 10. Coating 20 may be located at least on the substrate 10. When coating 20 is located on the first surface (here, the upper surface) of the substrate 10, the first surface has high wear resistance and heat resistance. When coating 20 is located on the second surface (here, the side surface) of the substrate 10, the second surface has high wear resistance and heat resistance.

[0030] Here, refer to Figure 3 and Figure 4 The specific structure of coating 20 will be explained. Figure 3 This is a cross-sectional view showing an example of coating 20 in an embodiment. Additionally, Figure 4 It means Figure 3 An enlarged schematic diagram of section H is shown.

[0031] like Figure 3 As shown, coating 20 has a first coating 23 located above intermediate layer 22 and a second coating 24 located above first coating 23.

[0032] (First Coating 23)

[0033] The first coating 23 comprises: at least one element selected from the group consisting of Al, Group 5 elements, Group 6 elements and Group 4 elements excluding Ti; at least one element selected from the group consisting of C and N; Si and Cr.

[0034] Specifically, the first coating 23 contains Al, Cr, Si, and N. That is, the first coating 23 can be an AlCrSiN layer containing AlCrSiN nitrides as Al, Cr, and Si. Also, the expression "AlCrSiN" means that Al, Cr, Si, and N exist in any proportion, and does not mean that Al, Cr, Si, and N must exist in a 1:1:1:1 ratio.

[0035] When a first coating 23 containing the metal (e.g., Si) contained in the intermediate layer 22 is placed on top of the intermediate layer 22, the adhesion between the intermediate layer 22 and the coating 20 is high. As a result, the coating 20 is difficult to peel off from the intermediate layer 22, and therefore the coating 20 has high durability.

[0036] like Figure 4 As shown, the first coating 23 can exhibit a striped structure when observed in cross-section using a transmission electron microscope. Specifically, the first coating 23 has multiple first layers 23a and multiple second layers 23b. The first coating 23 has the first layers 23a and second layers 23b alternately stacked in the thickness direction. The first layer 23a is in contact with the intermediate layer 22, and the second layer 23b is formed on the first layer 23a.

[0037] The thicknesses of the first layer 23a and the second layer 23b can be less than 50 nm each. Because the first layer 23a and the second layer 23b are formed very thinly, the residual stress is small, making it difficult for peeling and cracking to occur, thus increasing the durability of the coating 20.

[0038] The first coating 23 may contain crystals with a cubic crystal structure. In this case, the first layer 23a and the second layer 23b may each contain crystals with a cubic crystal structure.

[0039] Layer 1 23a and layer 23b may contain Si and at least one metallic element, and the content of the metallic element may differ between layers 1 23a and 23b. Layer 1 23a and layer 23b may exhibit the same crystal orientation or different crystal orientations.

[0040] Figure 5 This is a schematic diagram used to illustrate the Al, Cr, and Si contents of the first layer 23a and the second layer 23b.

[0041] Layer 1 23a and layer 23b contain Al, Cr, Si, and N. Here, the Al content in layer 1 23a is defined as the first Al content, the Cr content in layer 1 23a as the first Cr content, and the Si content in layer 1 23a as the first Si content. Similarly, the Al content in layer 23b is defined as the second Al content, the Cr content in layer 23b as the second Cr content, and the Si content in layer 23b as the second Si content.

[0042] In this case, the first Al content can be greater than the second Al content, the first Cr content can be less than the second Cr content, and the first Si content can be greater than the second Si content.

[0043] The coated cutting tool 1 with the first coating 23 having this structure has high hardness and excellent resistance to chipping.

[0044] In addition, the total of Al, Cr and Si accounts for more than 98 atomic% of the metallic elements contained in the first coating 23.

[0045] The coated cutting tool 1 with the first coating 23 having this structure has higher hardness and better resistance to chipping.

[0046] Furthermore, the proportion of Al in the metal elements of the first coating 23 can be 38 atomic% or more and 55 atomic% or less. The proportion of Cr in the metal elements of the first coating 23 can be 33 atomic% or more and 48 atomic% or less. The proportion of Si in the metal elements of the first coating 23 can be 4 atomic% or more and 15 atomic% or less.

[0047] The coated cutting tool 1 with the first coating 23 having this structure has improved oxidation resistance and excellent wear resistance.

[0048] In addition, the difference between the first Al content and the second Al content can be more than 1 atomic% and less than 9 atomic%.

[0049] The coated cutting tool 1 with the first coating 23 having this structure can maintain high oxidation resistance and high hardness, and can also alleviate the stress inside the coating and has excellent wear resistance.

[0050] The coated cutting tool 1 with the first coating 23 having this structure has particularly high hardness.

[0051] In addition, the difference between the first Cr content and the second Cr content can be more than 1 atomic% and less than 12 atomic%.

[0052] The coated cutting tool 1 with the first coating 23 having this structure has better wear resistance.

[0053] The coated cutting tool 1 with the first coating 23 having this structure has particularly excellent resistance to chipping.

[0054] In addition, the difference between the first Si content and the second Si content can be more than 0.5 atomic% and less than 5 atomic%.

[0055] The coated cutting tool 1 with the first coating 23 having this structure has particularly high hardness.

[0056] In addition, the thickness of the first layer 23a and the second layer 23b can be greater than 1 nm and less than 20 nm.

[0057] The coated cutting tool 1 with the first coating 23 having this structure has excellent hardness and chipping resistance.

[0058] The first coating can be formed, for example, by physical vapor deposition. Examples of physical vapor deposition methods include ion plating and sputtering. As an example, when the first coating is formed by ion plating, the coating can be formed by the following method.

[0059] First, as an example, prepare metal targets of Cr, Si and Al, or composite alloy targets, or sintered targets.

[0060] Secondly, the target, which serves as the metal source, is evaporated and ionized through methods such as arc discharge or glow discharge. The ionized metal reacts with nitrogen (N2) gas from a nitrogen source, and the vapor phase is deposited on the surface of the substrate. Through these steps, an AlCrSiN layer can be formed.

[0061] In the above steps, the temperature of the substrate can be 500-600℃, the pressure can be 1.0-6.0Pa, and a DC bias voltage of -50 to -200V can be applied to the substrate to make the arc discharge current 100-200A.

[0062] The composition of the first coating can be adjusted by independently controlling the voltage and current values ​​applied during arc discharge and glow discharge to each of the aluminum metal target, chromium metal target, aluminum-silicon composite alloy target, and chromium-silicon composite alloy target. Furthermore, the composition of the first coating can also be adjusted by controlling the coating time and atmospheric pressure. In one embodiment, the ionization amount of the target metal can be varied by changing the voltage and current values ​​during arc discharge and glow discharge. Additionally, the ionization amount of the target metal can be periodically varied by periodically changing the current value during arc discharge and glow discharge for each target. By periodically changing the current value during arc discharge and glow discharge of the target at intervals of 0.01 to 0.5 minutes, the ionization amount of the target metal can be periodically varied. This allows a structure in which the content ratio of each metal element varies periodically along the thickness direction of the coating.

[0063] When performing the above steps, the composition of Al, Si and Cr is changed by reducing the amount of Al and Si and increasing the amount of Cr. Then, the composition of Al, Si and Cr is changed by increasing the amount of Al and Si and decreasing the amount of Cr. In this way, a first coating 23 having a first layer and a second layer can be produced.

[0064] (Second coating 24)

[0065] The second coating 24 can contain Ti, Si, and N. That is, the second coating 24 can be a nitride layer (TiSiN layer) containing Ti and Si. Also, the description of "TiSiN layer" means that Ti, Si, and N exist in any proportion, and does not mean that Ti, Si, and N must exist in a 1:1:1 ratio.

[0066] Therefore, for example, a low coefficient of friction in the second coating 24 can improve the anti-adhesion properties of the coated tool 1. Additionally, for example, a high hardness in the second coating 24 can improve the wear resistance of the coated tool 1. Furthermore, for example, a high oxidation initiation temperature in the second coating 24 can improve the oxidation resistance of the coated tool 1.

[0067] The second coating 24 can exhibit a striped structure when observed in cross-section using a transmission electron microscope. Specifically, the second coating 24 can have two or more layers arranged in the thickness direction. For example, the second coating 24 can have a third and a fourth layer alternately arranged in the thickness direction. Furthermore, the second coating 24 can contain crystals with a cubic crystal structure. In this case, each layer constituting the striped structure of the second coating 24 can each contain crystals with a cubic crystal structure.

[0068] The striped structure of the second coating 24 may contain Si and at least one metal element in each layer, and the content of the metal element may vary in each layer.

[0069] In the second coating 24, the contents of Ti (hereinafter referred to as "Ti content"), Si (hereinafter referred to as "Si content"), and N (hereinafter referred to as "N content") can be repeatedly increased or decreased along the thickness direction of the second coating 24. Furthermore, among the metallic elements contained in the second coating 24, the combined content of Ti and Si can be 98 atomic% or more.

[0070] The coated cutting tool 1 with the second coating 24 having this configuration has high toughness and excellent impact resistance. Specifically, the coated cutting tool 1 with the second coating 24 having this configuration has excellent resistance to chipping and burring.

[0071] Furthermore, the second coating 24 may have a portion where the increase / decrease cycle of Ti content differs from that of Si content. Here, the increase / decrease cycle, for example, is the distance along the thickness direction of the second coating 24 from the position where the Ti content (or Si content) is at its maximum (or minimum) to the next position where it is at its maximum (or minimum).

[0072] The coated cutting tool 1 with the second coating 24 having this structure maintains high hardness and improves toughness, exhibiting excellent impact resistance.

[0073] The increase / decrease cycles of Ti content, Si content, and N content can be greater than 1 nm and less than 15 nm.

[0074] The coated tool 1 with the second coating 24 having this structure has its residual stress inside the coating mitigated, the coating's adhesion improved, and its impact resistance enhanced.

[0075] The proportion of Ti in the metal elements of the second coating 24 is more than 80 atomic% and less than 95 atomic%, and the proportion of Si in the metal elements of the second coating 24 can be more than 5 atomic% and less than 20 atomic%.

[0076] The coated tool 1 with the second coating 24 having this structure maintains high hardness and the adhesion of the coating is also improved. In addition, the coating has excellent toughness and exhibits high impact resistance.

[0077] The proportion of Ti in the metallic elements of the second coating 24 can be above 82 atomic% and below 90 atomic%.

[0078] The coated cutting tool 1 with the second coating 24 having this structure has further improved toughness and exhibits high impact resistance.

[0079] The second coating 24 can be formed by physical vapor deposition, just like the first coating 23. As an example, the second coating, which is made of TiSiN and has a striped structure, can be fabricated in an ion plating process using a titanium metal target and a titanium-silicon composite alloy target, by independently controlling the voltage and current values ​​applied to each target during arc discharge and glow discharge.

[0080] In coating 20 having a first coating 23 and a second coating 24, the lattice constant of the cubic crystal structure (hereinafter referred to as "cubic crystal") contained in one of the two layers (the third and fourth layers) of the striped structure of the second coating 24 is taken as the first lattice constant. Furthermore, the lattice constant of the cubic crystal contained in the other layer (the third and fourth layers) of the striped structure of the second coating 24 is taken as the second lattice constant. Also, when the cubic crystal is formed across two layers, the portion of the lattice constant located in one layer is taken as the first lattice constant, and the portion located in the other layer is taken as the second lattice constant.

[0081] In this case, the difference between the magnitude of the first lattice constant and the magnitude of the second lattice constant in the coated tool 1 and coating 20 of the embodiment can be greater than 0% and less than 0.1%.

[0082] Traditionally, coatings consisting of two alternating layers have a large difference between the lattice constant a1 of the a-axis of crystals in one layer and the lattice constant a2 of crystals in the other layer. Therefore, large strain exists at the interface between the two layers, resulting in low thermal stability, low wear resistance during cutting, and low thermal shock resistance. In contrast, in the coating 20 of this embodiment, the difference between the lattice constant a1 of the a-axis of cubic crystals in one layer and the lattice constant a2 of cubic crystals in the other layer is small. Therefore, in the coating 20 of this embodiment, the strain at the interface between the two layers is small. Thus, compared to existing products, the coating 20 of this embodiment exhibits higher thermal stability, higher stability during cutting (i.e., higher wear resistance and thermal shock resistance).

[0083] Furthermore, coating 20 contains Si in both the first coating 23 and the second coating 24. This reduces residual stress between layers, thereby further improving thermal stability.

[0084] Furthermore, coating 20 has a first coating 23 containing Al and Cr. As a result, the oxidation resistance and lubricity of coating 20 can be improved.

[0085] In addition, coating 20 has a second coating 24 containing Ti. This improves the resistance to chipping.

[0086] Here, an example is given where coating 20 has both a first coating 23 and a second coating 24, but coating 20 may have at least one of the first coating 23 and the second coating 24.

[0087] For example, coating 20 may be a structure having only the first coating 23 among the first coating 23 and the second coating 24. In this case, the difference between the lattice constant a1 of the cubic crystallization contained in one of the two layers (first layer 23a and second layer 23b) of the first coating 23 and the lattice constant a2 of the cubic crystallization contained in the other layer may be greater than 0% and less than 0.1%.

[0088] Alternatively, coating 20 can also be a structure having only the second coating 24, which is one of the first coating 23 and the second coating 24. In this case, the difference between the lattice constant a1 of the cubic crystal along the a-axis in one of the two layers (the third and fourth layers) of the second coating 24 and the lattice constant a2 of the cubic crystal in the other layer can be greater than 0% and less than 0.1%. The third and fourth layers can exhibit the same crystal orientation or different crystal orientations.

[0089] (Middle layer 22)

[0090] An intermediate layer 22 may be provided between the substrate 10 and the coating 20. Specifically, the intermediate layer 22 is in contact with the upper surface of the substrate 10 on one side (the lower surface in this case) and with the lower surface of the coating 20 (the first coating 23) on the other side (the upper surface in this case).

[0091] The interlayer 22 has a higher bonding strength with the substrate 10 than with the coating 20. Examples of metallic elements possessing this property include Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si, Y, and Ti. The interlayer 22 contains at least one of the aforementioned metallic elements. For example, the interlayer 22 may contain Ti. Furthermore, while Si is a half-metal element, in this specification, half-metal elements are also included among metallic elements.

[0092] When the intermediate layer 22 contains Ti, the Ti content in the intermediate layer 22 can be 1.5 atomic% or more. For example, the Ti content in the intermediate layer 22 can also be 2.0 atomic% or more.

[0093] The intermediate layer 22 may also contain components other than the aforementioned metallic elements (Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si, Y, Ti). However, from the viewpoint of bonding with the substrate 10, the intermediate layer 22 may contain at least 95 atomic% of the aforementioned metallic elements in total. More preferably, the intermediate layer 22 may contain at least 98 atomic% of the aforementioned metallic elements in total. Furthermore, the proportion of metallic components in the intermediate layer 22 can be specified, for example, by analysis using an EDS (energy-dispersive X-ray spectroscopy) instrument attached to a STEM (scanning transmission electron microscope).

[0094] Thus, in the coated cutting tool 1 of this embodiment, by providing an intermediate layer 22 between the substrate 10 and the coating 20, which has a higher wettability with the substrate 10 than with the coating 20, the adhesion between the substrate 10 and the coating 20 can be improved. Furthermore, because the adhesion between the intermediate layer 22 and the coating 20 is also high, it is difficult for the coating 20 to peel off from the intermediate layer 22.

[0095] Furthermore, the thickness of the intermediate layer 22 can be, for example, greater than 0.1 nm and less than 20.0 nm.

[0096] <Cutting Tools>

[0097] Next, refer to Figure 6 The structure of the cutting tool having the above-mentioned coated tool 1 will be described. Figure 6 This is a front view showing an example of a cutting tool used in an embodiment.

[0098] like Figure 6 As shown, the cutting tool 100 of the embodiment has a coated tool 1 and a tool holder 70 for fixing the coated tool 1.

[0099] The handle 70 is from the first end ( Figure 6 The upper end of the middle) faces the second end ( Figure 6 A rod-shaped member extending from the lower end of the blade. The handle 70 is made of, for example, steel or cast iron. Among these components, high-toughness steel is particularly preferred.

[0100] The tool holder 70 has a groove 73 at its first end. The groove 73 is the part for mounting the coated tool 1, and has a support surface that intersects the rotation direction of the workpiece and a limiting side that is inclined relative to the support surface. On the support surface, there is a threaded hole for tightening the bolt 75, which will be described later.

[0101] The coated cutting tool 1 is located in the slot 73 of the tool holder 70 and is mounted on the tool holder 70 by a bolt 75. That is, the bolt 75 is inserted into the through hole 5 of the coated cutting tool 1, and the front end of the bolt 75 is inserted into the threaded hole formed in the support surface of the slot 73, so that the threads are tightened. Thus, the coated cutting tool 1 is mounted on the tool holder 70 with the cutting edge protruding outward from the tool holder 70.

[0102] In this embodiment, a cutting tool for so-called turning is exemplified. Examples of turning include, for instance, internal diameter machining, external diameter machining, and grooving. However, the cutting tool is not limited to turning. For example, a coated tool 1 can also be used for hobbing. Examples of cutting tools for hobbing include, for instance, end mills such as face mills, front end mills, side end mills, and grooving end mills, as well as end mills such as single-flute end mills, multi-flute end mills, tapered end mills, and ball end mills.

[0103] Example

[0104] The following describes specific embodiments of the present invention. However, the present invention is not limited to the embodiments shown below.

[0105] Samples No. 1 to No. 6 were prepared with coatings on a substrate composed of WC-based cemented carbide, where WC particles were the hard phase and Co was the main binder phase. The coatings of Samples No. 1 to No. 6 all exhibited a striped structure when observed in cross-section using a transmission electron microscope. Among Samples No. 1 to No. 6, Samples No. 1 to No. 3 correspond to embodiments of the present invention, while Samples No. 4, No. 5, and No. 6 correspond to comparative examples.

[0106] The substrate is composed of WC, the intermediate layer is composed of a Ti-containing layer, the first coating is composed of an AlCrSiN layer, and the second coating is composed of a TiSiN layer. The coated cutting tool is used as sample No. 1. Sample No. 1 corresponds to the embodiment of the present invention.

[0107] In 1×10 -3 The substrate was heated under reduced pressure (Pa) to a surface temperature of 550°C. Then, argon gas was introduced as the atmosphere gas, maintaining the pressure at 3.0 Pa. Next, argon bombardment was performed for 11 minutes with a bias voltage of -400 V. The pressure was then reduced to 0.1 Pa, and an arc current of 150 A was applied to the Ti metal evaporation source for 0.3 minutes, forming a Ti-containing layer on the substrate surface. The argon bombardment and Ti-containing layer formation processes were repeated a total of three times, resulting in a Ti-containing intermediate layer with a thickness of 8 nm. However, in the second and third argon bombardment processes, the bias voltage was set to -200 V.

[0108] <Treatment conditions for argon bombardment>

[0109] (1) Bias voltage: -400V

[0110] (2) Pressure: 3 Pa

[0111] (3) Processing time: 11 minutes

[0112] <Film formation conditions containing Ti layer>

[0113] (1) Arc current: 150A

[0114] (2) Bias voltage: -400V

[0115] (3) Pressure: 0.1a

[0116] (4) Processing time: 0.3 minutes

[0117] <Argon bombardment conditions after the second time>

[0118] (1) Bias voltage: -200V

[0119] (2) Pressure: 3 Pa

[0120] (3) Processing time: 1 minute

[0121] The Ti-containing layer may also contain other metallic elements introduced by diffusion. The Ti-containing layer can contain 50–98 atomic percent of metallic elements other than Ti.

[0122] Next, the first coating is formed. An atmospheric gas and N2 gas (as a nitrogen source) are introduced into the chamber containing the substrate, maintaining the internal pressure of the chamber at 3 Pa. Then, for Al metal, Cr metal, and Al... 52 Si 48 An alloy evaporation source was subjected to a bias voltage of -130V, and arc currents of 135–150A, 120–150A, and 110–120A were applied repeatedly over a period of 0.04 minutes, at intervals of 15 minutes, to form a first coating (Al) with an average thickness of 1.8 μm. 50 Cr 43 Si7)N / (Al 48 Cr 45 Si7)N layer.

[0123] Next, a second coating is formed. For Ti metal and Ti... 52 Si 48 A bias voltage of -100V was applied to the alloy evaporation source, and arc currents of 100–200A and 100–200A were applied repeatedly at a period of 0.04 minutes over 10 minutes to form a second coating (Ti) with an average thickness of 1.2 μm. 91 Si9)N / (Ti 89 Si 11 )N layers.

[0124] Samples No. 2 to No. 6 were prepared by changing the metal or alloy evaporation source based on the preparation method of sample No. 1.

[0125] For each sample No.1 to No.6, the lattice constant of the cubic crystal contained in the coating was measured.

[0126] The lattice constant was measured using electron beam diffraction or fast Fourier transform of TEM images by a transmission electron microscope JEM-ARM200F.

[0127] In addition, the measurement conditions are as follows.

[0128] Accelerating voltage: 200kV

[0129] In addition, using coated double-edged carbide ball end mills (model: 2KMBL0200-0800-S4) from samples No. 1 to No. 6, proceed under the following conditions.

[0130] <Cutting Test Conditions>

[0131] (1) Cutting method: slot machining

[0132] (2) Workpiece material: SKD11H

[0133] (3) Rotation speed: 16900 min －1

[0134] (4) Table feed: 1320mm / min

[0135] (5) Depth of cut (ap×ae): 0.08mm×0.2mm

[0136] (6) Cutting condition: wet

[0137] (7) Coolant: oil mist

[0138] (8) Evaluation method: The judgment is based on the number of impacts that lead to collapse.

[0139] Figure 7 This is a table showing the coating composition, lattice constant measurement results, and cutting test results for samples No.1 to No.6. Here, Figure 7 The lattice constant difference (nm) shown is represented by |L1-L2| when the first lattice constant is L1 and the second lattice constant is L2. Furthermore, the lattice constant difference (%) is represented by |L1-L2| / {(L1+L2) / 2}.

[0140] The coating of sample No. 1 has a first coating and a second coating. The first coating has a first layer and a second layer alternately arranged in the thickness direction. The second coating has a third layer and a fourth layer alternately arranged in the thickness direction. The first and second layers contain Al, Cr, Si, and N. The proportions of Al, Cr, and Si in the first layer are 50 atomic%, 43 atomic%, and 7 atomic%, respectively; the proportions of Al, Cr, and Si in the second layer are 48 atomic%, 46 atomic%, and 6 atomic%, respectively. Additionally, the third and fourth layers contain Ti and Si. The proportions of Ti and Si in the third layer are 91 atomic% and 9 atomic%, respectively; the proportions of Ti and Si in the fourth layer are 89 atomic% and 11 atomic%, respectively.

[0141] The coating of sample No. 2 consists only of coating 1 and coating 2. Coating 1 has layers 1 and 2 alternately arranged in the thickness direction, and layers 1 and 2 contain Al, Cr, Si, and N. The proportions of Al, Cr, and Si in the metal elements of layer 1 are 50 atomic%, 43 atomic%, and 7 atomic%, respectively; the proportions of Al, Cr, and Si in the metal elements of layer 2 are 48 atomic%, 46 atomic%, and 6 atomic%, respectively.

[0142] The coating of sample No. 3 has a second coating, which is one of a first coating and a second coating. The second coating has a third layer and a fourth layer alternately arranged in the thickness direction, and the third layer and the fourth layer contain Ti, Si and N. The proportions of Ti and Si in the metal elements of the third layer are 91 atomic% and 9 atomic%, respectively, and the proportions of Ti and Si in the metal elements of the fourth layer are 89 atomic% and 11 atomic%, respectively.

[0143] The coating of sample No. 4 has two layers (referred to as "layer 5" and "layer 6") arranged alternately in the thickness direction. Layer 5 contains Al, Cr, and N, and layer 6 contains Al, Ti, and N. The proportions of Al and Cr in the metal elements of layer 5 are 50 atomic% and 50 atomic%, respectively, and the proportions of Al and Ti in the metal elements of layer 6 are 60 atomic% and 40 atomic%, respectively.

[0144] The coating of sample No. 5 has two layers (referred to as "layer 7" and "layer 8") arranged alternately in the thickness direction. Layer 7 contains Ti, Al, and N, and layer 8 contains Al, Cr, and N. The proportions of Ti and Al in the metal elements of layer 7 are 70 atomic% and 30 atomic%, respectively, and the proportions of Al and Cr in the metal elements of layer 8 are 50 atomic% and 50 atomic%, respectively.

[0145] The coating of sample No. 6 has two layers (referred to as "layer 7" and "layer 8") arranged alternately in the thickness direction. Layer 7 contains Al, Cr, and N, and layer 8 contains Al, Cr, Si, and N. The proportions of Ti and Al in the metal elements of layer 7 are 50 atomic% and 50 atomic%, respectively, and the proportions of Al, Cr, and Si in the metal elements of layer 8 are 48 atomic%, 46 atomic%, and 6 atomic%, respectively.

[0146] like Figure 7As shown, the lattice constant difference (%) of sample No. 1 is 0.010%, and the lattice constant difference (nm) is 0.00004nm. Sample No. 2 has a lattice constant difference (%) of 0.016%, and the lattice constant difference (nm) is 0.00027nm. Sample No. 3 has a lattice constant difference (%) of 0.010%, and the lattice constant difference (nm) is 0.00004nm. Sample No. 4 has a lattice constant difference (%) of 0.210%, and the lattice constant difference (nm) is 0.00352nm. Sample No. 5 has a lattice constant difference (%) of 0.500%, and the lattice constant difference (nm) is 0.00841nm. Sample No. 6 has a lattice constant difference (%) of 0.022%, and the lattice constant difference (nm) is 0.00036nm. Thus, the lattice constant differences of samples No. 1 to No. 3, corresponding to embodiments of the present invention, are smaller than those of samples No. 4 and No. 5, corresponding to comparative examples. Furthermore, sample No. 6 does not contain Si in at least one layer of each layer in its striped structure. Therefore, the coated cutting tool of the present invention exhibits high thermal stability. Also, sample No. 1 has a first coating and a second coating, but... Figure 7 The result shown is the difference between the magnitude of the first lattice constant and the magnitude of the second lattice constant in the second coating.

[0147] In addition, such as Figure 7 As shown, the number of impacts leading to breakage in the cutting test was 127,000 for sample No. 1, 122,000 for sample No. 2, 123,000 for sample No. 3, 33,000 for sample No. 4, 30,000 for sample No. 5, and 50,000 for sample No. 6.

[0148] Thus, compared with the comparative examples No. 4, No. 5, and No. 6, samples No. 1 to No. 3 in the embodiments of the present invention had more impact cycles leading to breakage. This result indicates that the coated cutting tool of the present invention exhibits high wear resistance and thermal shock resistance during cutting.

[0149] As described above, the coated cutting tool (coated cutting tool 1, for example) has a substrate (substrate 10, for example) and a coating (coating 20, for example) situated on the substrate. The coating contains crystals with a cubic crystal structure. The coating exhibits a striped structure in cross-sectional observation using a transmission electron microscope. The striped structure comprises two layers alternately arranged in the thickness direction. The two layers contain Si and at least one metallic element. The content of the metallic element in the two layers is different from that in the other layer. Each of the two layers contains crystals with a cubic crystal structure. When the lattice constant of the cubic crystal structure contained in one of the two layers is taken as the first lattice constant, and the lattice constant of the cubic crystal structure contained in the other of the two layers is taken as the second lattice constant, the difference between the magnitude of the first lattice constant and the magnitude of the second lattice constant is greater than 0% and less than 0.1%.

[0150] Therefore, the coated cutting tool according to the embodiment can improve thermal stability.

[0151] besides, Figure 1 The shape of the coating tool 1 shown is only an example and is not intended to limit the shape of the coating tool of the present invention. The coating tool of the present invention may, for example, have a rotating shaft and a rod-shaped body extending from a first end toward a second end, a cutting edge located at the first end of the body, and a groove extending spirally from the cutting edge toward the second end of the body.

[0152] Further effects and variations can be readily derived by those skilled in the art. Therefore, the invention is presented in a broader manner, not limited to the specific details and representative embodiments expressed and described above. Thus, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0153] Symbol Explanation

[0154] 1 Coated cutting tools

[0155] 2. Blade body

[0156] 5 Through holes

[0157] 10 Matrix

[0158] 20 Coatings

[0159] 22 Intermediate Layer

[0160] 23 First Coating

[0161] 24 Second Coating

[0162] 70 Knife Handle

[0163] 73 Card Slots

[0164] 75 bolts

[0165] 100 Cutting Tools

Claims

1. A coated cutting tool having a substrate and a coating disposed on the substrate, The coating comprises crystals with a cubic crystal structure. The coating exhibits a striped structure when observed in cross-section using a transmission electron microscope. This striped structure has two layers that are alternately arranged in the thickness direction. The two layers contain Si and at least one metallic element, the amounts of which differ, and each layer contains crystals with the cubic crystal structure described above. The lattice constant of the crystal with the cubic crystal structure contained in one of the two layers is taken as the first lattice constant. When the lattice constant of the crystal with the cubic crystal structure contained in the other of the two layers is taken as the second lattice constant, The difference between the magnitude of the first lattice constant and the magnitude of the second lattice constant is greater than 0% and less than 0.1%. The coating has a first coating on the substrate and a second coating on the first coating. The first coating and the second coating, when observed in cross-section using a transmission electron microscope, each exhibit a striped structure. The striped structure of the first coating has a first layer and a second layer alternately arranged in the thickness direction. The striped structure of the second coating has a third and a fourth layer alternately arranged in the thickness direction. The first layer and the second layer contain Al, Cr, Si, and N. The third and fourth layers contain Ti, Si, and N.

2. A cutting tool, comprising: A rod-shaped knife handle with a groove at the end; The coated cutting tool of claim 1 is located within the slot.

Images