Surface-coated cutting tool

Abstract

A surface-coated cutting tool wherein a coating layer has an A layer with an average thickness of 0.3-6.0 μm, the A layer is a layered structure in which an Aα layer, an Aβ layer, and an Aγ layer, which each have an average thickness of 1.0-8.0 nm, are layered in order, the Aα layer includes a compound having the composition (AlxCr1–x)N (where the average value xavg of x satisfies 0.25≤xavg≤0.55), the Aβ layer includes a compound having the composition (AlyTi1–y)N (where the average value yavg of y satisfies 0.60≤yavg≤0.80), and the Aγ layer includes a compound having the composition (AlzTi1–z–mMim)N (where M1 is one or more elements among B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, and W, the average value zavg of z satisfies 0.35≤zavg≤0.55, and the average value mavg of m satisfies 0.01≤mavg≤0.20).

Description

surface coated cutting tools

[0001] The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool). This application claims priority to Japanese Patent Application No. 2024-172839, filed on 1 October 2024. All provisions contained in said Japanese application are incorporated herein by reference.

[0002] Conventionally, coated tools have been known in which a coating layer is formed on a substrate such as a tungsten carbide (hereinafter referred to as WC)-based cemented carbide. Furthermore, proposals have been made to obtain coated tools with even better cutting performance by adjusting the composition and layer structure of this coating layer.

[0003] For example, Patent Document 1 contains Ti ｘ Al １－ｘ N and Ti ｙ Al １－ｙ A coated tool is described in which two types of compounds N (0 ≤ x < 0.5, 0.5 < y ≤ 1) are alternately layered, and the overall composition of the laminate has a coating layer that is richer in aluminum than stoichiometrically. This coated tool is said to have excellent wear resistance and fracture resistance.

[0004] Furthermore, for example, Patent Document 2 describes a coated tool having a coating layer in which layers A containing MeN (where Me is one or more selected from the group consisting of Ti, Nb, Hf, V, Ta, Zr, Cr, and Al), B containing (Ti, Al)N, and C containing (Ti, Si)N are laminated in the order A / B / A / C / A / B / A / C..., and the coating layer is said to have excellent wear resistance.

[0005] Japanese Patent Publication No. 7-97679, European Patent Application Publication No. 2098611

[0006] This invention has been made in view of the above circumstances and proposals, and aims to provide a cutting tool that has excellent wear resistance not only when used for cutting steel and cast iron, but also when used for cutting various types of stainless steel, superalloys, and other materials.

[0007] The surface-coated cutting tool according to an embodiment of the present invention has a substrate and a coating layer. The coating layer includes an A layer having an average thickness At of 0.3 μm or more and 6.0 μm or less. The A layer has a laminated structure including an Aα layer with an average thickness of αt, an Aβ layer with an average thickness of βt, and an Aγ layer with an average thickness of γt. The αt, the βt, and the γt are all 1.0 nm or more and 8.0 nm or less. The Aα layer includes a compound having a composition of (Al ｘ Cr １－ｘ )N (the average value x of x ａｖｇ satisfies 0.25 ≦ x ａｖｇ ≦ 0.55). The Aβ layer includes a compound having a composition of (Al ｙ Ti １－ｙ )N (the average value y of y ａｖｇ satisfies 0.60 ≦ y ａｖｇ ≦ 0.80). The Aγ layer includes a compound having a composition of (Al ｚ Ti １－ｚ－ｍ M1 ｍ )N (M1 is one or two elements selected from the group of B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, W. The average value z of z ａｖｇ satisfies 0.35 ≦ z ａｖｇ ≦ 0.55, and the average value m of m ａｖｇ satisfies 0.01 ≦ m ａｖｇ [[ID=_30]]≦ 0.20).

[0008] The surface-coated cutting tool according to the embodiment may satisfy the following item (1).

[0009] (1) It further includes a B layer having an average thickness Bt of 0.1 μm or more and 3.0 μm or less on the A layer; the B layer has a laminated structure including a Bα layer with an average thickness of αt', a Bβ layer with an average thickness of βt', and a Bγ layer with an average thickness of γt'. The αt', the βt', and the γt' are all 1.0 nm or more and 8.0 nm or less. The Bα layer includes a compound having a composition of (Al ａ Cr １－ａ )N (the average value a of a ａｖｇ satisfies 0.22 ≦ a ａｖｇ ≦ 0.52). The Bβ layer includes a compound having a composition of (Al ｂ Ti １－ｂ) N (mean value of b b ａｖｇ 0.57 ≤ b ａｖｇ The compound comprises a compound having a composition that satisfies ≤0.77, and the Bγ layer is (Al ｃ Ti １－ｃ－ｎ M2 ｎ )N(M2 is one or two of the elements B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, W, and the average value of c ａｖｇ 0.32 ≤ c ａｖｇ The condition ≤ 0.52 is satisfied, and the mean value of n is n ａｖｇ 0.01 ≤ n ａｖｇ It contains a compound having a composition that satisfies ≤0.20, and the difference x ａｖｇ -a ａｖｇ , y ａｖｇ -b ａｖｇ , z ａｖｇ -c ａｖｇ Both values ​​are between 0.03 and 0.20.

[0010] The aforementioned surface-coated cutting tool exhibits excellent wear resistance not only when used to cut steel and cast iron, but also when used to cut stainless steel and superalloys.

[0011] This is a schematic longitudinal cross-sectional view of the coating layer in a surface-coated cutting tool according to one embodiment of the present invention. This is a schematic longitudinal cross-sectional view of the coating layer in a surface-coated cutting tool according to another embodiment of the present invention. This is an example of an explanatory diagram for measuring the thickness of layers Aα, Aβ, and Aγ. This is another example of an explanatory diagram for measuring the thickness of layers Aα, Aβ, and Aγ.

[0012] The inventors diligently studied coating layers in order to obtain cutting tools that have excellent wear resistance when used for cutting stainless steel and other materials, while ensuring wear resistance performance in cutting steel and cast iron. As a result, they obtained the following findings (1) to (4).

[0013] (1) When layers containing AlTiN compounds with a high Al content and layers containing AlCrN compounds are alternately laminated, with both having an average thickness on the order of nanometers, the decrease in hardness of the layer containing AlTiN compounds with a high Al content that occurs during machining is suppressed, improving the wear resistance and fracture resistance of the coating layer, and exhibiting excellent performance in the machining of steel and cast iron.

[0014] (2) However, this alternating lamination does not always have sufficient oxidation resistance, making it difficult to suppress boundary damage that occurs during the cutting of various stainless steels and superalloys.

[0015] (3) Therefore, in the alternating lamination of layers composed of the aforementioned AlTiN compound and layers composed of AlCrN compound, by further adding a layer containing a TiAlM1N compound (where M1 is one or two elements selected from the group consisting of B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, and W) which has a small difference in lattice constant from the compounds in the two layers and an average thickness on the order of nanometers, a three-layer alternating lamination structure can be obtained, thereby suppressing the decrease in hardness and improving oxidation resistance. As a result, a coating layer can be obtained that has excellent cutting performance not only when used for cutting steel and cast iron but also when used for cutting stainless steel and superalloys.

[0016] (4) Furthermore, by providing a layered structure on top of the alternating layered structure of (3) that has the same configuration as (3) but with a different atomic ratio of each compound, a coating layer can be obtained that has even better cutting performance when used to cut not only steel and cast iron but also stainless steel and superalloys.

[0017] The following describes in more detail the covering tool according to an embodiment of the present invention. In this specification and the claims, when a numerical range is expressed using "L to M", it is synonymous with "greater than or equal to L and less than or equal to M", and the range includes the numerical values ​​of the upper limit (M) and the lower limit (L). Furthermore, when a unit is specified only for the upper limit (M), the upper limit (M) and the lower limit (L) have the same unit.

[0018] I. The First Embodiment The first embodiment will be described below.

[0019] 1. Coating Layer The layer structure of the coating layer of the coating tool according to the first embodiment of the present invention is schematically shown in Figure 1, and the coating layer (2) includes a plurality of A layers (3) on a base layer (4) provided on a substrate (1). In Figure 1, each A layer (3) is a laminate of thin layers having an average thickness on the order of nanometers, i.e., a laminate of three types of layers: Aα layer (6), Aβ layer (7), and Aγ layer (8). In Figure 1, Aα layer (6), Aβ layer (7), and Aγ layer (8) are also laminated on the white areas of the A layer (3). A surface layer (5) is provided on top of the A layers. Note that the base layer (4) and the surface layer (5) are optional layers and are not essential.

[0020] (1) Average thickness of layer A In this embodiment, the average thickness of layer A (the average thickness of the total laminated layers Aα, Aβ, and Aγ) is preferably 0.3 μm or more and 6.0 μm or less, and more preferably 0.4 μm or more and 5.0 μm or less. The reason is that when the average thickness is within this range, it is possible to achieve excellent wear resistance without insufficient fracture resistance during cutting.

[0021] (2) Structure of Layer A Layer A is a laminate of nanometer-order Aα, Aβ, and Aγ layers. The average thicknesses αt, βt, and γt of the Aα, Aβ, and Aγ layers are preferably 1.0 nm to 8.0 nm, and more preferably 1.0 nm to 5.0 nm. The reason is that satisfying these average thickness relationships suppresses grain refinement of the compounds in the Aα, Aβ, and Aγ layers that constitute Layer A, preventing a decrease in the hardness of Layer A and ensuring that both excellent wear resistance and fracture resistance are reliably achieved.

[0022] (4) Number of layers of Aα, Aβ, and Aγ There are no particular restrictions on the number of layers of Aα, Aβ, and Aγ (the total number of layers of Aα, Aβ, and Aγ), but 55 to 1196 is preferred, and 145 to 1023 is even more preferred. The reason is that when the number of layers is within this range, the refinement of the crystal grains of the compounds in each layer constituting the A layer is suppressed, there is no decrease in the hardness of the A layer, and both excellent wear resistance and excellent fracture resistance can be reliably achieved.

[0023] Furthermore, the Aα, Aβ, and Aγ layers can be stacked in the order of Aα layer on top of Aβ layer, Aγ layer on top of Aβ layer, and Aα layer on top of Aγ layer, as long as any of the Aα, Aβ, or Aγ layers can be the starting layer of the stacking process, which is the layer in contact with the substrate (or the layer in contact with the underlayment layer if there is an underlayment layer described later), or the ending layer of the stacking process, which is the layer that becomes the tool surface (or the layer in contact with the surface layer if there is an underlayment layer).

[0024] (5) Composition of the compounds in the Aα, Aβ, and Aγ layers The A layer is composed of the Aα, Aβ, and Aγ layers. The compounds that make up the Aα layer are (Al ｘ Cr １－ｘ ) N (mean value of x x ａｖｇ However, 0.25 ≤ x ａｖｇ (Satisfying ≤0.55) The compounds constituting the Aβ layer are (Al ｙ Ti １－ｙ )N(mean value of y y ａｖｇ However, 0.60 ≤ y ａｖｇ (Satisfying ≤0.80) The compounds constituting the Aγ layer are (Al ｚ Ti １－ｚ－ｍ M1 ｍ )N(M1 is one or two elements selected from the group consisting of B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, W, and the average value of z is z ａｖｇ However, 0.35 ≤ z ａｖｇ The condition ≤ 0.55 is satisfied, and the average value of m is m ａｖｇ However, 0.01 ≤ m ａｖｇ It is preferable to have a composition that satisfies ≤ 0.20.

[0025] When the composition of the compounds contained in each of the Aα, Aβ, and Aγ layers falls within this range, the refinement of the crystal grains in each layer constituting the A layer is suppressed, preventing a decrease in the hardness of the A layer, and ensuring that excellent wear resistance, fracture resistance, and improved oxidation resistance are reliably achieved. Average value x ａｖｇ , y ａｖｇ , z ａｖｇ , m ａｖｇ The more preferable range for each is 0.35 ≤ x ａｖｇ ≤ 0.55, 0.65 ≤ y ａｖｇ ≤ 0.78, 0.40 ≤ z ａｖｇ ≤0.55, 0.01 ≤mａｖｇ The value is ≤ 0.10.

[0026] Furthermore, according to one example of the manufacturing method described later, the ratio of (AlCr), the compound constituting the Aα layer, to N, the ratio of (AlTi), the compound constituting the Aβ layer, to N, and the ratio of (AiTiM1), the compound constituting the Aγ layer, to N are each manufactured to be 1:1. However, there may be cases where the ratio is not unintentionally 1:1.

[0027] (6) Other coating layers: Although the aforementioned objective (solving the problem to be solved) can be sufficiently achieved with layer A alone, a surface layer and / or a base layer may be provided in addition to these layers to give the coating tool more desirable properties.

[0028] (6-1) Surface layer A surface layer may be optionally provided on the tool surface side of layer A. An example of the surface layer is a layer made of one or more Ti nitrides or Al nitrides, not limited to stoichiometric compositions, with an average thickness of 0.1 to 1.5 μm. When this Ti nitride layer is provided, the Ti nitride itself has a golden hue, so for example, the usage state of the coated tool can be determined by the change in hue. The average thickness of the Ti nitride layer for this determination can be, for example, 0.1 to 1.0 μm.

[0029] (6-2) Underlayer An underlayer may be provided between the substrate and layer A. The underlayer may consist of one or more layers of Ti carbides, nitrides, or carbonitrides with a thickness of 0.1 to 1.5 μm, or one or more layers of TiAl carbides, nitrides, or carbonitrides. The composition of these carbides, nitrides, and carbonitrides is not limited to stoichiometric compositions. Providing an underlayer improves the adhesion between the substrate and layer A, further enhancing chipping resistance.

[0030] (6-3) Layers that may occur unintentionally In this embodiment, the film is formed so that no layers other than the A layer (Aα layer, Aβ layer, Aγ layer), the surface layer, and the underlayer (compounds other than those constituting these layers) are present. However, when changing the layer to be formed, changes in pressure and temperature within the film deposition apparatus inevitably occur, and unintended layers (compounds) different from these layers (compounds) may be formed. Even if these unintended layers (compounds) are present, the aforementioned problems are resolved.

[0031] 2. Substrate (1) Material The substrate used in this embodiment can be any of the conventionally known substrate materials, as long as it does not hinder the achievement of the above-mentioned objectives. For example, it is preferable to use any of the following: cemented carbide (WC-based cemented carbide, including those containing Co in addition to WC, and further containing carbonitrides such as Ti, Ta, and Nb), cermet (mainly composed of TiC, TiN, TiCN, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cBN sintered body, or diamond sintered body.

[0032] (2) The shape of the base material is not particularly restricted as long as it is a shape that can be used as a cutting tool, and examples include the shape of an insert and the shape of a drill.

[0033] II. Second Embodiment A second embodiment will be described. Matters that overlap with the description of the first embodiment will be omitted.

[0034] 1. Coating Layer The layer structure of the coating layer of the coating tool according to the second embodiment of the present invention is schematically shown in Figure 2, and the coating layer (2) has a plurality of A layers (3) on a substrate (1) and an underlayer. In Figure 2, each A layer (3) is a laminate of thin layers having an average thickness on the order of nanometers, i.e., a laminate of Aα layers (6), Aβ layers (7), and Aγ layers (8). Note that in Figure 2, Aα layers (6), Aβ layers (7), and Aγ layers (8) are also laminated in the white areas of the lower layer A (3). A plurality of B layers (9) are provided on top of the A layers. Each B layer (9) is a laminate of thin layers having an average thickness on the order of nanometers, i.e., a laminate of Bα layers (10), Bβ layers (11), and Bγ layers (12). Note that in Figure 2, Bα layers (10), Bβ layers (11), and Bγ layers (12) are also laminated in the white areas of the B layers (9). A surface layer (5) is provided on top of layer B (9). Note that the base layer (4) and the surface layer (5) are optional layers and are not required.

[0035] (1) The average thickness and composition of layer A, the number of layers Aα, Aβ, and Aγ, and their composition are the same as in the first embodiment. Furthermore, as long as the layers Aα, Aβ, and Aγ are stacked in the order of Aβ layer on top of Aα layer, Aγ layer on top of Aβ layer, and Aα layer on top of Aγ layer, any of the Aα, Aβ, and Aγ layers may be the starting layer of the stack that is in contact with the substrate (or the layer in contact with the underlayment if there is an underlayment described later), or it may be the ending layer of the stack that is in contact with layer B.

[0036] (2) Average thickness of layer B In this embodiment, the average thickness of each layer B is preferably 0.1 μm or more and 3.0 μm or less. It is even more preferably 0.2 μm or more and 2.5 μm or less. The reason is that when the average thickness is within this range, it is possible to achieve excellent wear resistance without insufficient fracture resistance during cutting.

[0037] (3) Composition of the B layer Each B layer is a stack of nanometer-order Bα, Bβ, and Bγ layers. The average thicknesses of the Bα, Bβ, and Bγ layers, αt', βt', and γt', respectively, are preferably 1.0 nm or more and 8.0 nm or less. It is even more preferable that the average thicknesses of αt', βt', and γt' are each 1.0 nm or more and 5.0 nm or less. The reason for this is that satisfying these average thickness relationships suppresses grain refinement of the compounds in the Bα, Bβ, and Bγ layers constituting the B layer, preventing a decrease in the hardness of the B layer and ensuring that both excellent wear resistance and excellent fracture resistance are reliably achieved.

[0038] (4) Number of layers of Bα, Bβ, and Bγ There are no particular restrictions on the number of layers of Bα, Bβ, and Bγ (total number of layers of Bα, Bβ, and Bγ), but 21 to 580 is more preferable, and 55 to 269 is even more preferable. The reason is that if it is less than 21, it may not be possible to sufficiently prevent crack propagation that occurs during cutting, which can reduce fracture resistance, and if it exceeds 580, the number of repetitions increases, which can cause the crystal grains of the compound in the lower layer B to become finer and reduce wear resistance.

[0039] Furthermore, the Bα, Bβ, and Bγ layers can be stacked in the following order: Bα layer on top of Bβ layer, Bγ layer on top of Bβ layer, and Bα layer on top of Bγ layer. In this case, any of the Bα, Bβ, or Bγ layers may be the starting layer of the stacking process that is in contact with layer A, or it may be the ending layer of the stacking process that is on the surface of the tool (or, if there is a surface layer described later, the layer in contact with the surface layer).

[0040] (5) The composition of compounds contained in each of the Bα, Bβ, and Bγ layers: The lower layer is composed of the Bα, Bβ, and Bγ layers. The compounds constituting the Bα layer are (Al ａ Cr １－ａ ) N (average value of a a ａｖｇ However, 0.22 ≤ a ａｖｇ (Satisfying ≤0.52), the compounds constituting the Bβ layer are (Al ｂ Ti １－ｂ )N(Average value of B b ａｖｇ However, 0.57 ≤ b ａｖｇ (Satisfying ≤0.77), the compounds constituting the Bγ layer are (Alｃ Ti １－ｃ－ｎ M2 ｎ ), N (M2 is one or two elements selected from the group consisting of B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, W, and the average value c of c ａｖｇ is such that 0.32 ≤ c ａｖｇ ≤ 0.52, and the average value n of n ａｖｇ is such that 0.01 ≤ n ａｖｇ ≤ 0.20), and has a composition represented by, and the differences x ａｖｇ -a ａｖｇ , y ａｖｇ -b ａｖｇ , z ａｖｇ -c ａｖｇ are each preferably 0.03 or more and 0.20 or less.

[0041] The more preferable ranges of the average values a ａｖｇ , b ａｖｇ , c ａｖｇ , n ａｖｇ are respectively 0.32 ≤ a ａｖｇ ≤ 0.52, 0.62 ≤ y ａｖｇ ≤ 0.75, 0.35 ≤ c ａｖｇ ≤ 0.52, 0.01 ≤ n ａｖｇ ≤ 0.10, and the differences x ａｖｇ -a ａｖｇ , y ａｖｇ -b ａｖｇ , z ａｖｇ -c ａｖｇ are each 0.03 or more, and the upper limit values are each more preferably 0.09 or less. When the compositions of the compounds constituting each of the Bα layer, Bβ layer, and Bγ layer are within this range, the above object can be surely achieved. Note that M1 and M2 may be the same or different.

[0042] According to an example of the manufacturing method described later, the ratios of (AlCr) to N, (AlTi) to N, and (AlTiM2) to N, which are the compounds constituting the Bα layer, Bβ layer, and Bγ layer, respectively, are each manufactured to be 1:1, but there may be cases where they do not become 1:1 unintentionally.

[0043] (6) Other layers are the same as in the first embodiment, and for layers that may occur unintentionally, the term "layers other than layer A (layer Aα, layer Aβ, layer Aγ), the surface layer and the underlayer (compounds other than the compounds that constitute these layers)" is read as "layers other than layer A (layer Aα, layer Aβ, layer Aγ), layer B (layer Bα, layer Bβ, layer Bγ), the surface layer and the underlayer (compounds other than the compounds that constitute these layers)."

[0044] 2. The substrate is the same as the substrate according to the first embodiment.

[0045] III. Measurement Method (1) Average Thickness of Layer A, Layer B, Underlayer and Surface Layer The average thickness of the lower layer A, upper layer B, and other layers constituting the coating layer can be measured using a High-Angle Annular Dark Field Scanning Transmission Electron Microscope (HAADF-STEM) and an Energy Dispersive X-ray Spectrometer (EDS) attached to the STEM. Specifically, first, a longitudinal section of a thin film of approximately 30-100 nm thickness is prepared using a focused ion beam (FIB) processing machine, with the observation plane perpendicular to the substrate surface. This can be determined by observing the longitudinal section of the coated tool (for inserts, the section perpendicular to the surface of the substrate, ignoring minute irregularities on the substrate surface and considering it as a flat surface; for shaft tools such as drills, the section perpendicular to the shaft). This observation (analysis using EDS and HAADF-STEM) is performed at five or more locations parallel to the substrate surface at intervals of 3 μm, and the results are arithmetic mean.

[0046] Here, the surface of the substrate is determined by observing this longitudinal section, identifying the interface between the substrate and layer A (or the underlying layer if one exists) through elemental mapping, and then arithmetically calculating the average straight line from the resulting interface roughness curve.

[0047] 2. Average thickness of layers Aα, Aβ, Aγ, Bα, Bβ, and Bγ Since these layers have an average thickness on the order of nanometers, it is preferable to measure the average thickness using HAADF-STEM.

[0048] The following explanation concerns the measurement of the average thickness of layers Aα, Aβ, and Aγ, and the average composition of the compounds constituting these layers. However, if layers Aα, Aβ, and Aγ are replaced with layers Bα, Bβ, and Bγ, respectively, the explanation will then describe the measurement of the average thickness of layers Bα, Bβ, and Bγ, and the average composition of the compounds constituting these layers.

[0049] The average thickness and average composition were measured by line analysis using an EDS attached to the TEM in a HAADF-STEM image (observation magnification: 2 million times), from the surface of the coating layer in the thickness direction (direction perpendicular to the surface of the substrate), covering a length that includes at least 10, preferably 50, of these layers (a length in which at least 10, preferably 50, maximum values ​​of parameter i, described later, can be observed), and the content of aluminum based on the number of atoms A was determined. Ａｌ And the content of titanium based on the number of atoms A Ｃｒ The content A of the additive element M (M is referred to as M1 in the Aγ layer and M2 in the Bγ layer) based on the number of atoms. Ｍ Measure.

[0050] Aluminium content based on atomic number A Ａｌ Chromium content based on the number of atoms A Ｃｒ , and the content A of the additive element M based on the number of atoms Ｍ Based on this, we plot the curves of the line analysis based on the following equation, and define the local maximums of each curve as points Pi, Qi, and Mi. Point Pi: ({A Ａｌ / (A Ａｌ +A Ｃｒ +A Ｍ )}×100)(%) Point Qi:({A Ｃｒ / (A Ａｌ +A Ｃｒ +A Ｍ )}×100)(%) Point Mi: ({A Ｍ / (A Ａｌ +A Ｃｒ +A Ｍ )} × 100) (%) The lower limit of parameter i is 1, and the upper limit is at least 10, preferably 50. Also, from the starting point of the line analysis to the first point P １Points Q and M between them are ignored. The explanation using Figures 3 and 4 applies regardless of whether the starting layer for layer A is layer Aα, layer Aβ, or layer Aγ, and regardless of whether the starting layer for layer B is layer Bα, layer Bβ, or layer Bγ.

[0051] Next, as shown in Figure 3, let PQi be the midpoint between adjacent Pi and Qi, QMi be the midpoint between adjacent Qi and Mi, and MMi be the midpoint between adjacent Mi and Pi+1. Let the distance from PQi to QMi be the thickness of the Aβ layer (κi), the distance from QMi to MPi be the thickness of the Aγ layer (λi), and the distance from MPi to PQi+1 be the thickness of the Aα layer (μi). We then determine these thicknesses κi, λi, and μi at a predetermined number of points, and average them to determine the average thickness of the Aβ layer, the average thickness of the Aγ layer, and the average thickness of the Aα layer, respectively.

[0052] Furthermore, since the explanation of each intermediate position based on Figure 3 does not apply to stacking orders different from the stacking order shown in Figure 3, as shown in Figure 4, the intermediate position between adjacent Pi and Mi is defined as PMi, the intermediate position between adjacent Mi and Qi is defined as MQi, and the intermediate position between adjacent Qi and Pi+1 is defined as QPi. The distance from PMi to MQi is defined as the thickness of the Aγ layer (ρi), the distance from MQi to QPi is defined as the thickness of the Aβ layer (σi), and the distance from Qpi to PMi+1 is defined as the thickness of the Aα layer (τi). These thicknesses ρi, σi, and τi are determined at a predetermined number of points, and these are averaged to determine the average thickness of the Aγ layer, the average thickness of the Aβ layer, and the average thickness of the Aγ layer, respectively. In addition, the average composition of the compounds contained in the Aα, Aβ, and Aγ layers can be determined by EDS surface analysis (surface analysis width shall be 20 times or more the thickness) within the average thickness of the Aα, Aβ, and Aγ layers obtained by these processes.

[0053] IV. Manufacturing Method The coating layer of the coating tool of this embodiment can be manufactured, for example, using a Cathodic Arc Evaporation (CAE) type PVD apparatus (hereinafter simply referred to as a PVD apparatus). Furthermore, the coating can be formed by using targets with compositions corresponding to the compositions of the Aα, Aβ, and Aγ layers for the A layer deposition, and targets with compositions corresponding to the compositions of the Bα, Bβ, and Bγ layers for the B layer deposition.

[0054] For example, the deposition conditions for layers Aα, Aβ, and Aγ, and layers Bα, Bβ, and Bγ are: Cathode current: 50 to 300 A, Bias voltage: -20 to -300 V, Atmosphere gas: N ２ The ambient pressure is 0.5 to 9.0 Pa, the ambient temperature is 250 to 650°C, and the rotation speed of the rotary table is 0.7 to 3.0 rpm.

[0055] Next, embodiments corresponding to the first and second embodiments will be described. Here, as an embodiment, we will describe an application to a coated tool with an insert shape using a WC-based cemented carbide as the base material. The base material can be made of the material described above. The shape may also be a drill or an end mill, as described above.

[0056] 1. Process common to the first and second embodiments First, as raw material powders, Co powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ３ C ２ Powder and WC powder were prepared, and these raw material powders were blended according to the formulation shown in Table 1. Wax was then added and wet-mixed in a ball mill for 72 hours, dried under reduced pressure, and then press-molded at a pressure of 100 MPa. These compacted bodies were sintered at 1400°C for 1 hour under a vacuum atmosphere of 6 Pa, and processed to the predetermined dimensions to produce substrates 1 to 3 made of WC-based cemented carbide with an insert shape conforming to the ANSI standard SEEN42AFTN1.

[0057] Next, substrates 1 to 3 were ultrasonically cleaned in acetone and dried. Then, in order to form a coating layer using a PVD apparatus, they were mounted along the outer circumference at a predetermined radial distance from the central axis on a rotating table within the apparatus. A target of a predetermined composition was also placed as the cathode electrode (evaporation source).

[0058] Next, the PVD apparatus was evacuated and maintained at a vacuum of 0.3 Pa or less. The apparatus was then heated to 600°C with a heater, and a DC bias voltage of -1000V was applied to the substrate rotating on a rotary table. A current of 100A was then passed between the cathode electrode and the anode electrode to bombard the substrate surface.

[0059] 2. Processing in the First Embodiment A nitrogen atmosphere with the partial pressure shown in Table 2 and the furnace temperature were maintained as the reaction gas in the PVD apparatus. Then, a DC bias voltage shown in Table 2 was applied to the substrate rotating on the rotary table, and an arc discharge was generated by passing a current between the alloy electrode for forming the lower layer A (Aα layer, Aβ layer, Aγ layer) and the anode electrode to form the Aα, Aβ, and Aγ layers of predetermined thickness.

[0060] The deposition of layers Aα, Aβ, and Aγ was repeated a predetermined number of times to obtain a predetermined number of layers of the lower layer A, and Examples 1 to 9 shown in Table 8 were prepared. In some examples, the underlayer and / or surface layer shown in Table 4 was deposited using the deposition conditions shown in Table 3.

[0061] 3. Processing in the Second Embodiment The PVD apparatus was maintained with a nitrogen atmosphere at the partial pressure shown in Table 5 and at the furnace temperature as the reaction gas. A DC voltage shown in Table 5 was applied to the substrate rotating on the rotary table, and an arc discharge was generated by passing a current between the alloy electrode for forming the lower layer A (Aα layer, Aβ layer, Aγ layer) and the anode electrode to form the Aα, Aβ, and Aγ layers of a predetermined thickness. This was repeated a predetermined number of times to deposit a predetermined number of lower layers A.

[0062] Next, the furnace temperature was maintained in a nitrogen atmosphere with the partial pressure shown in Table 5. Then, the DC voltage shown in Table 5 was applied to the substrate, and an arc discharge was generated between the alloy electrode for forming the B layer (Bα layer, Bβ layer, Bγ layer) and the anode electrode to form the Bα, Bβ, and Bγ layers of predetermined thickness.

[0063] The deposition of the Bα, Bβ, and Bγ layers was repeated a predetermined number of times to form a predetermined number of lower layers A. This produced the coated tools (hereinafter referred to as "Examples") 11 to 19 shown in Table 9. In some examples, the underlayer and / or surface layer shown in Table 4 was deposited using the deposition conditions shown in Table 3.

[0064] 4. To compare the processing of the comparative examples, the coating layers of the comparative examples were deposited onto substrates 1 to 3 using the same PVD apparatus as in the examples, under the conditions shown in Tables 7 to 9, to produce the comparative example coating tools (hereinafter referred to as "comparative examples") 1 to 9 and 11 to 19 shown in Tables 10 to 13. In the comparative examples, the lower layer and / or surface layer were formed in the same manner as in the examples.

[0065] The average thickness and average composition of the coating layer were measured using the method described above.

[0066]

[0067]

[0068]

[0069] In Table 3, "-" indicates that there is no matching entry.

[0070]

[0071] In Table 4, "-" indicates that there is no matching entry.

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] Next, cutting tests 1 and 2 were performed for Examples 1 to 9, 11 to 19 and Comparative Examples 1 to 9, 11 to 19 under the following cutting conditions. One SEEN42AFTN1 insert was mounted in an SE445R0506E holder, and these cutting tests were performed.

[0082] Cutting Test 1: Workpiece: Block material (SCM440) with a width of 110 mm and a length of 200 mm. Cutting speed: 180 m / min. Depth of cut: 1.8 mm. Feed rate: 0.14 mm / tooth. Cutting was performed up to a cutting length of 5.0 m, and the wear width of the flank surface was measured to observe the wear condition of the cutting edge. The results are shown in Tables 14-15.

[0083] Cutting Test 2: Workpiece: Block material with a width of 60 mm and a length of 200 mm (Ni-19Cr-19Fe-3Mo-0.9Ti-0.5Al-5.1(Nb+Ta)) Cutting speed: 60 m / min. Depth of cut: 1.8 mm Feed rate: 0.07 mm / tooth. Cutting was performed up to a cutting length of 2.5 m, and the wear width of the flank surface was measured. The results of observing the wear state of the cutting edge are shown in Tables 16-17.

[0084]

[0085]

[0086]

[0087]

[0088] In Tables 14-17, the "*" in the flank wear width column indicates that the tool reached its service life before reaching the cutting length specified for each cutting test, and therefore the time at which the service life was reached, i.e., the cutting life time (seconds), is indicated.

[0089] According to the results in Tables 14-17, Examples 1-9 and 11-19 all showed no abnormal damage such as chipping or peeling, demonstrating excellent wear resistance and chipping resistance. In contrast, Comparative Examples 1-9 and 11-19 clearly reached the end of their lifespan in a short time due to the occurrence of chipping or the progression of flank wear.

[0090] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described herein, and all modifications within the scope of the claims are intended to be included in the meaning of equivalents and within the scope of the claims.

[0091] 1 Base 2 Covering layer 3 A layer 4 Base layer 5 Surface layer 6 Aα layer 7 Aβ layer 8 Aγ layer 9 B layer 10 Bα layer 11 Bβ layer 12 Bγ layer

Claims

1. A surface-coated cutting tool including a substrate and a coating layer, wherein the coating layer includes an A layer having an average thickness At of 0.3 μm or more and 6.0 μm or less, and the A layer has a laminated structure including an Aα layer having an average thickness of αt, an Aβ layer having an average thickness of βt, and an Aγ layer having an average thickness of γt, and αt, βt, and γt are all 1.0 nm or more and 8.0 nm or less. The Aα layer contains a compound having a composition of (Al ｘ Cr １－ｘ )N (the average value x of x ａｖｇ satisfies 0.25 ≤ xavg ≤ 0.55). The Aβ layer contains a compound having a composition of (Al ｙ Ti １－ｙ )N (the average value y of y ａｖｇ satisfies 0.60 ≤ y ａｖｇ ≤ 0.80). The Aγ layer contains a compound having a composition of (Al ｚ Ti １－ｚ－ｍ M1 ｍ )N (M1 is one or two elements selected from the group consisting of B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, and W, the average value z of z ａｖｇ satisfies 0.35 ≤ z ａｖｇ ≤ 0.55, and the average value m of m ａｖｇ satisfies 0.01 ≤ m ａｖｇ ≤ 0.20). A surface-coated cutting tool characterized by the above.

2. The A layer further comprises a B layer having an average thickness Bt of 0.1 μm to 3.0 μm, wherein the B layer has a laminated structure comprising, in order, a Bα layer with an average thickness αt', a Bβ layer with an average thickness βt', and a Bγ layer with an average thickness γt', where αt', βt', and γt' are all between 1.0 nm and 8.0 nm, and the Bα layer is made of (Al ａ Cr １－ａ ) N (average value of a a ａｖｇ 0.22 ≤ a ａｖｇ The compound comprises a compound having a composition that satisfies ≤0.52, and the Bβ layer is (Al ｂ Ti １－ｂ ) N (mean value of b b ａｖｇ 0.57 ≤ b ａｖｇ The compound comprises a compound having a composition that satisfies ≤0.77, and the Bγ layer is (Al ｃ Ti １－ｃ－ｎ M2 ｎ )N(M2 is one or two elements selected from the group consisting of B, Si, V, Zr, Nb, Mo, La, Ce, Hf, Ta, and W, and the average value of c is c ａｖｇ 0.32 ≤ c ａｖｇ The condition ≤ 0.52 is satisfied, and the mean value of n is n ａｖｇ 0.01 ≤ n ａｖｇ It contains a compound having a composition that satisfies ≤ 0.20, and the difference x ａｖｇ -a ａｖｇ , y ａｖｇ -b ａｖｇ , z ａｖｇ -c ａｖｇ The surface-coated cutting tool according to claim 1, characterized in that all of these values ​​are 0.03 or more and 0.20 or less.

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