Surface coated cutting tools

Abstract

A coated tool in which: a mean thickness At of a lower layer A is 0.3 to 6.0 μm, a mean thickness Bt of an upper layer B is 0.1 to 3.0 μm, and 2.0≤At / Bt≤5.0; the lower layer A comprises alternately stacked layers of an A1α layer having a mean thickness αt and an A1β layer having a mean thickness βt, where 0.5 nm≤αt≤4.0 nm, 0.5 nm≤βt≤4.0 nm, and 0.7≤βt / αt≤1.3; the A1α layer composition is AlxTi1-xN (where an average value of x, xavg, is 0.35≤xavg≤0.55), the A1β layer composition is AlyTi1-yN (where an average value of y, yavg, is 0.60≤yavg≤0.80), and 1.2≤yavg / xavg; and the upper layer B composition is AlaTi1-a-bSibN (where an average value of a, aavg, and an average value of b, bavg, satisfy the relationships 0.35≤aavg≤0.60, and 0.00<bavg≤0.15).

Description

Technical Field

[0001] The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool). This application claims priority based on Japanese Patent Application No. 2022-45633, filed on March 22, 2022. All the descriptions in the Japanese patent application are incorporated herein by reference.

Background Art

[0002] Conventionally, as a coated tool, a coated layer is formed on a substrate such as a tungsten carbide (hereinafter represented by WC) - based cemented carbide. And, by adjusting the composition and layer structure of this coated layer, a proposal has been made to obtain a coated tool with further improved cutting performance.

[0003] For example, in Patent Document 1, two types of layers of Ti , , d , b , 1-y , 1-x , f , e , c ,

[0004] , a , y Al 1-x N and Ti y Al 1-y N (0 ≦ x < 0.5, 0.5 < y ≦ 1) are alternately repeated to form a laminate, and a coated tool having a coated layer with a stoichiometrically aluminum-rich overall composition of the laminate is described, and the coated tool is said to have excellent wear resistance and chipping resistance.

[0004] Also, for example, in Patent Document 2, the coated layer includes an alternating layer, the thickness of each alternating layer is 2 nm or more and 100 nm or less, and includes one or more first layers and second layers. The composition of the first layer is Ti a Al b Si c N (0.25 ≦ a ≦ 0.45, 0.55 ≦ b ≦ 0.75, 0 ≦ c ≦ 0.1, a + b + c = 1), and the composition of the second layer is Ti d Al e Si f N (0.35 ≦ d ≦ 0.55, 0.45 ≦ e ≦ 0.65, 0 ≦ f ≦ 0.1, d + e + f = 1), and 0.05 ≦ d - a ≦ 0.2 and 0.05 ≦ b - e ≦ 0.2. A coated tool is described, and the coated tool is said to have an improved tool life.

[0005] Furthermore, for example, Patent Document 3 describes a coated tool having a coating layer in which a nanobeam diffraction pattern is indexed to the crystalline structure of WC, the coating layer having an a-layer made of carbide containing W and Ti and a mutual laminated layer disposed on the a-layer, the a-layer having a film thickness of 1 nm to 10 nm, the mutual laminated layer being formed by alternating b-layers made of nitrides or carbonitrides of Al and Ti, in which the Al content (atomic %) is 50% to 70% relative to the total amount of metal elements, and c-layers made of nitrides or carbonitrides of Al and Ti, in which the Al content (atomic %) is 70% or more relative to the total amount of metal elements, the difference in Al content (atomic %) between the b-layers and the c-layers being 10% to 30%, and the coated tool is said to have excellent durability even when cutting stainless steel.

[0006] Additionally, for example, Patent Document 4 describes a coated tool in which the outermost layer of the coating layer is a coating film made of a hexagonal nitride or carbonitride containing, in atomic % of metal components only, 60% to 80% Al, 5% to 10% Si, and the remainder Ti, and the coated tool is said to have durability. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 7-97679 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-193004 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-110259 [Patent Document 4] Japanese Patent Application Publication No. 2017-185551 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances and proposals, and an object of the present invention is to provide a cutting tool that has excellent wear resistance even when used for high-speed cutting of not only steel and cast iron but also stainless steel and the like. Here, high-speed cutting refers to cutting in which the cutting speed is 30% or more faster than normal cutting. [Means for solving the problem]

[0009] The surface-coated cutting tool according to an embodiment of the present invention comprises: A substrate and a coating layer provided on the substrate, the coating layer has a lower layer A and an upper layer B on the lower layer A, the average thickness At of the lower layer A is 0.3 μm or more and 6.0 μm or less, the average thickness Bt of the upper layer B is 0.1 μm or more and 3.0 μm or less, and 2.0≦At / Bt≦5.0; The lower layer A has an alternating laminate of an A1α layer having an average thickness of αt and an A1β layer having an average thickness of βt, 0.5 nm≦αt≦4.0 nm, 0.5 nm≦βt≦4.0 nm, 0.7≦βt / αt≦1.3, The composition of the A1α layer is Al x Ti 1-x N(x is the average value of x avg However, 0.35≦x avg ≦0.55), The composition of the A1β layer is Al y Ti 1-y N(y is the average value of y avg However, 0.60≦y avg ≦0.80), 1.2≦y avg / x avg Satisfied, The composition of the upper layer B is Al a Ti 1-a-b Si b N(a) is the average value of a avg , b is the average value of b avg However, 0.35≦a avg ≦0.60, 0.00 avg ≦0.15).

[0010] ​ The surface-coated cutting tool according to the above embodiment may satisfy the following requirements.

[0011] The lower layer A is a lower layer A1 on the substrate side and a lower layer A2 on the upper layer B side, the average thickness A1t of the lower layer A1 and the average thickness A2t of the lower layer A2 satisfy the following conditions: 0.1 μm≦A1t≦4.5 μm, 0.2 μm≦A2t≦4.0 μm, and 0.5≦A1t / A2t≦3.0; the lower layer A1 is the alternating laminate of the A1α layer and the A1β layer, The lower layer A2 is an alternating laminate of A2γ layers having an average thickness γt and A2δ layers having an average thickness δt, 1.5 nm≦γt≦8.0 nm, 1.5 nm≦δt≦8.0 nm, 0.7≦δt / γt≦1.3, 1.0<(γt+δt) / (αt+βt)≦6.0, The composition of the A2γ layer is Al z Ti 1-z N(z is the average value of z avg However, 0.30≦z avg ≦0.50), The composition of the A2δ layer is Al w Ti 1-w N(w is the average value of w avg However, 0.55≦w avg ≦0.75), 1.2≦w avg / z avg Satisfied, And 0.02≦(x avg -z avg )≦0.30, 0.02≦(y avg -w avg )≦0.30. [Effects of the Invention]

[0012] The surface-coated cutting tool exhibits excellent wear resistance when used for high-speed cutting of not only steel and cast iron but also stainless steel. [Brief explanation of the drawings]

[0013] [Figure 1]1 is a schematic diagram showing an example of a vertical cross section of a coating layer in a surface-coated cutting tool according to an embodiment of the present invention. [Figure 2] 10 is a schematic diagram showing an example of a vertical cross section of a coating layer in a surface-coated cutting tool according to another embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present inventors have conducted extensive research into coating layers in order to obtain a cutting tool that has excellent wear resistance even when used for high-speed cutting of stainless steel, etc., while still ensuring performance in cutting steel and cast iron. As a result, the present inventors have obtained the following findings (1) to (3).

[0015] (1) When a coating layer is formed by stacking an AlTiN layer with a high Al content and an AlTiN layer with a low Al content, each with an average thickness of 0.5 to 4.0 nm, the decomposition of AlTiN (presumably AlTiN decomposes into TiN and AlN) during cutting increases the hardness, resulting in a coated tool with excellent wear resistance for cutting steel and cast iron. However, if oxidation wear occurs in this coating layer, the tool may not be able to fully demonstrate its performance. In other words, if only AlTiN layers with different Al contents are stacked, oxidation damage can reduce wear resistance.

[0016] (2) Therefore, we considered providing a TiSiN layer on top of this AlTiN laminate to suppress the aforementioned oxidation wear in the coating layer. However, this TiSiN layer has low oxidation resistance, so boundary damage develops when, for example, cutting stainless steel. Furthermore, the lattice constant of the TiSiN layer is significantly different from that of the AlTiN layer, resulting in poor compatibility at the interface between the two layers.

[0017] (3) On the other hand, even if a TiAlSiN laminate with a different Si content is used instead of the AlTiN laminate, the decomposition of TiAlSiN (it is assumed that TiAlSiN decomposes into TiN, AlN, and Si3N4) is difficult to occur in the TiAlSiN laminate, and the improvement in wear resistance is small, so the wear resistance decreases.

[0018] As a result of further investigation, the present inventors have found that the above object can be achieved by providing a layer in which two AlTiN layers with different Al contents, each having an average thickness of 0.5 to 4.0 nm, are alternately stacked, and an AlTiN layer containing Si, i.e., an AlTiSiN layer, is provided on top of the layer.

[0019] Furthermore, it was also found that the above-mentioned object can be achieved more reliably by configuring the lower layers as a lower layer A1 on the substrate side and a lower layer A2 above it, the lower layer A1 being a layer formed by alternately laminating AlTiN layers having two different Al contents and the aforementioned average thickness, and the lower layer A2 being a layer formed by alternately laminating AlTiN layers having two different Al contents and an average thickness of 1.5 to 8.0 nm, and the Al content of the two AlTiN layers in the lower layer A1 being greater than the Al content of the two AlTiN layers in the lower layer A2.

[0020] The coated tool according to the embodiment of the present invention will be described in more detail below. In this specification and claims, when a numerical range is expressed using "L to M," this is synonymous with "at least L and at most M," and the range includes the numerical values ​​of the upper limit (M) and the lower limit (L). Furthermore, when a unit is stated only for the upper limit (M), the upper limit (M) and the lower limit (L) have the same unit.

[0021] I. First Embodiment A coated tool according to a first embodiment will be described below.

[0022] 1.Coating layer An example of the layer structure of the coating layer of the coated tool according to the first embodiment of the present invention is shown in Figure 1. The coating layer (2) has a lower layer A (3) on a substrate (1), and an upper layer B (4) on top of this lower layer A (3). In Figure 1, the lower layer A (3) is preferably a laminate of thin layers each having an average thickness of 0.5 to 4.0 nm, i.e., an alternating laminate of A1α layers (7) and A1β layers (8). In Figure 1, the A1α layers (7) and A1β layers (8) are also alternately laminated in the white portion of the lower layer A (3). In addition to these layers, the coating layer may have other layers, which will be described later.

[0023] (1) The sum of the average thickness of the lower layer A and the average thickness of the upper layer B In this embodiment, the sum of the average thickness of the lower layer A and the average thickness of the upper layer B is preferably 0.4 μm or more and 9.0 μm or less. This is because if it is less than 0.4 μm, excellent wear resistance cannot be exhibited over long periods of use, while if it exceeds 9.0 μm, the crystal grains tend to become coarse, making it difficult to achieve improved chipping resistance. This average thickness is more preferably 0.8 μm or more and 6.0 μm or less.

[0024] (2) Average thickness of each of the lower layer A and the upper layer B It is preferable that the average thickness At of the lower layer A is 0.3 μm or more and 6.0 μm or less, and the average thickness Bt of the upper layer B is 0.1 μm or more and 3.0 μm or less, and that 2.0≦At / Bt≦5.0. The reason for this is that when the average thickness At of the lower layer A and the average thickness Bt of the upper layer B are in this range, oxidation damage to the coating layer during cutting is suppressed, and the decomposition of TiAlN in the lower layer A into TiN and AlN enables improved wear resistance. The average thickness At of the lower layer A is more preferably 0.6 μm or more and 4.0 μm or less, and the average thickness Bt of the upper layer B is more preferably 0.2 μm or more and 2.0 μm or less, and more preferably 2.3≦At / Bt≦3.5.

[0025] Furthermore, by making the average thickness Bt of the upper layer B thinner than the average thickness At of the lower layer A, the lower layer A undergoes decomposition of AlTiN (AlTiN decomposes into TiN and AlN) during cutting, increasing the hardness and improving the wear resistance of the coating layer.

[0026] (3) Composition of Lower Layer A The lower layer A is an alternating laminate of A1α layers and A1β layers. The average thicknesses of the A1α layers and A1β layers, αt and βt, respectively, satisfy the following relationship: 0.5nm≦αt≦4.0nm, 0.5nm≦βt≦4.0nm, 0.7≦βt / αt≦1.3 It is more preferable that the following conditions are satisfied: 0.8 nm≦αt≦3.5 nm, 0.8 nm≦βt≦3.5 nm, and 0.8≦βt / αt≦1.2. The reason is that the above-mentioned object can be achieved if the relationship between these average thicknesses is satisfied.

[0027] (3-1) Number of layers of A1α and A1β If the number of stacked A1α layers is m and the number of stacked A1β layers is n, then |mn|≦1, and although there are no particular restrictions on m+n, it is preferably 50 to 2001. This is because if it is less than 50, the propagation of cracks that occur during cutting cannot be sufficiently prevented, which may reduce chipping resistance, and if it exceeds 2001, the number of repetitions increases, which may cause the crystal grains of the lower layer A to become finer, reducing wear resistance. It is more preferable that m+n be 100 to 1001.

[0028] The A1α layer and the A1β layer may be alternately laminated, and the layer on the substrate side and the layer on the tool surface side may be either one.

[0029] (3-2) A1α layer and A 1β Layer Composition The A1α layer and A 1β The composition of the layer is The A1α layer is Al x Ti 1-x N(x is the average value of x avg However, 0.35≦x avg ≦0.55), The A1β layer is Al y Ti 1-y N(y is the average value of y avg is 0.60≦y avg ≦0.80), 1.2≦y avg / x avg It is preferable to satisfy the following.

[0030] A1α layer, A 1βWhen the layer composition is in this range, the wear resistance is improved. The reason for this is presumably because AlTiN decomposes into TiN and AlN during cutting.

[0031] In addition, according to an example of the manufacturing method described later, the AlTiN constituting the lower layer is manufactured so that the ratio of (AlTi) to N is 1:1, but inevitably (unintentionally) there may be some in which the ratio is not 1:1. This also applies to the other nitrides described below.

[0032] (4) Composition of upper layer B The upper layer B is Al a Ti 1-a-b Si b N(a) is the average value of a avg , b is the average value of b avg However, 0.35≦a avg ≦0.60, 0.00 avg ≦0.15). If the composition of the upper layer B is within the above range, the oxidation resistance and wear resistance can be improved, but if it is outside this range, the oxidation resistance and wear resistance will decrease. This is presumably due to the precipitation of an AlN phase with a hexagonal crystal structure.

[0033] (5) Other layers (5-1) Layers that may be intentionally formed Layers that may be intentionally formed include the outermost layer and underlayer described below.

[0034] (5-1-1) Outermost layer An outermost layer may be selectively provided on the upper layer B. The outermost layer may be, for example, a TiN layer (the atomic ratio of Ti to N in the TiN layer is not limited to stoichiometric). When this TiN layer is provided, the TiN layer itself has a golden color tone, and therefore, for example, it can be used as an identification layer to distinguish whether the coated tool is unused or used based on a change in color tone. The average thickness of this TiN layer as an identification layer may be, for example, 0.1 to 1.0 μm. ​

[0035] (5-1-2) Base layer An underlayer may be optionally provided between the lower layer A and the substrate. Examples of the underlayer include Ti compound layers such as TiC, TiN, TiCN, and TiCNO, and AlTiN layers, and the average thickness thereof is 0.1 to 2.0 μm. When the average thickness is within this range, the adhesion between the lower layer A and the substrate may be further improved.

[0036] (5-2) Layers that are formed unintentionally (layers that may occur unavoidably) In this embodiment, the layers are deposited so that no layers other than the base layer, lower layer A (A1α layer and A1β layer), upper layer B, and outermost layer are present, i.e., these layers are in contact with each other. However, when changing the type of layer to be deposited, unintended changes in pressure or temperature within the deposition apparatus may occur, resulting in the formation of an unintended layer different from these layers.

[0037] 2 .Substrate (1)Material The substrate used in this embodiment can be any conventionally known substrate material as long as it does not hinder the achievement of the above-mentioned object. For example, it is preferably any of WC-based cemented carbide (including WC, Co, and carbides or carbonitrides of Ti, Ta, Nb, etc.), cermet (mainly composed of TiC, TiN, TiCN, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide), cBN sintered body, and diamond sintered body.

[0038] (2) Shape The shape of the substrate is not particularly limited as long as it is a shape that can be used as a cutting tool, and examples thereof include the shape of an insert and the shape of a drill.

[0039] II. Second Embodiment The second embodiment will be described below, and the description of the same parts as those of the first embodiment will be omitted.

[0040] 1.Coating layer An example of the layer structure of the coating layer of the coated tool according to the second embodiment is shown in FIG. 2. The coating layer (2) has a lower layer A (3) on the substrate (1), and an upper layer B (4) on top of the lower layer A (3). The lower layer A (3) is composed of a lower layer A1 (5) and a lower layer A2 (6). In FIG. 2, the lower layer A1 (5) is the same as in the first embodiment, and the lower layer A2 (6) is preferably composed of alternating thin layers having an average thickness of 1.5 to 8.0 nm. That is, the lower layer A1 (5) is preferably composed of alternating A1α layers (7) and A1β layers (8), and the lower layer A2 (6) is preferably composed of alternating A2γ layers (9) and A2δ layers (10). In addition, in Figure 2, the white areas of the lower layer A1 (5) and the lower layer A2 (6) also have A1α layers (7) and A1β layers (8), and A2γ layers (9) and A2δ layers (10) alternately laminated, respectively. In addition to these layers, the coating layer may also have other layers, which will be described later, in the same manner as in the first embodiment.

[0041] (1) The sum of the average thickness of the lower layer A and the average thickness of the upper layer B In the second embodiment, the sum of the average thickness of the lower layer A and the average thickness of the upper layer B is preferably in the same thickness range as in the first embodiment (and the more preferred thickness range is also the same).

[0042] (2) The average thickness of the lower layer A and the upper layer B In the second embodiment, the average thickness of each of the lower layer A and the upper layer B is preferably in the same thickness range as in the first embodiment (the more preferred thickness range is also the same).

[0043] (3) Composition of Lower Layer A In the second embodiment, the lower layer A includes lower layer A1 and lower layer A2. The average thickness A1t of lower layer A1 and the average thickness A2t of lower layer A2 are preferably 0.1 μm≦A1t≦4.5 μm, 0.2 μm≦A2t≦4.0 μm, and 0.5≦A1t / A2t≦3.0. When this relationship is satisfied, the above-mentioned object is achieved. The lower layer A1 and the lower layer A2 will be described in detail below.

[0044] (3-1) Lower layer A1 The lower layer A1 is made up of the same Alα layer and A as the lower layer A of the first embodiment. 1β It is preferable that the average thickness, the relational expression for the average thickness, and the composition, the relational expression for the composition described in the first embodiment are satisfied.

[0045] (3-2) Lower layer A2 The lower layer A2 is an alternating laminate of A2γ layers and A2δ layers. The average thicknesses γt and δt of the A2γ layers and A2δ layers, respectively, satisfy the following relationship: 1.5nm≦γt≦8.0nm, 1.5nm≦δt≦8.0nm, 0.7≦δt / γt≦1.3 and the A1α layer and A 1β For each average thickness of the layer, 1.0<(γt+δt) / (αt+βt)≦6.0 It is preferable to satisfy the following. The reason is that the above-mentioned object is achieved when this relational expression is satisfied. It is more preferable that (γt+δt) / (αt+βt) satisfies 1.2≦(γt+δt) / (αt+βt)≦3.0.

[0046] (3- 3 ) Composition of the A2γ and A2δ layers The composition of the A2γ layer is Al z Ti 1-z N(z is the average value of z avg However, 0.30≦z avg ≦0.50), The composition of the A2δ layer is Al w Ti 1-w N(w is the average value of w avg However, 0.55≦w avg ≦0.75), 1.2≦w avg / z avg It is preferable to satisfy the following. In addition, the A1α layer and A 1βThe composition of the layer and the A2γ and A2δ layers are 0.02≦(x avg -z avg )≦0.30, 0.02≦(y avg -w avg )≦0.30 It is preferable to satisfy the following.

[0047] A1α layer, A 1β When the composition of the A1 layer and the A2γ and A2δ layers are within this range, wear resistance is improved. The reason for this is that when the composition of these layers is within this range, a lower layer A with a higher Al content can be formed, and it is presumed that AlTiN decomposes into TiN and AlN during cutting. However, when the composition is outside this range, the difference in Al content between the lower layer A1 and the lower layer A2 becomes small, and this decomposition becomes insufficient. As a result, strain reduction by the lower layer A1 is insufficient, and the AlN phase with a hexagonal structure precipitates, which reduces the wear resistance of the coating layer.

[0048] (4) Average thickness and number of layers of the A1α layer, A1β layer, A2γ layer, and A2δ layer The average thicknesses of the A1α and A1β layers constituting the lower layers A1 and A2, respectively, are preferably 0.5 to 4.0 nm, and the average thicknesses of the A2γ and A2δ layers are preferably 1.5 to 8.0 nm. The number of stacked A1α layers (p) and the number of stacked A1β layers (q) in the lower layer A1, the number of stacked A2γ layers (r) and the number of stacked A2δ layers (s) in the lower layer A2, are |pq|≦1 and |rs|≦1, respectively. Although there are no particular restrictions on p + q and r + s, it is preferable that p + q be 50 to 901 and r + s be 20 to 551. The reason for this is that if p + q is less than 50 and r + s is less than 20, crack propagation during cutting cannot be sufficiently prevented, which may reduce chipping resistance. On the other hand, if p + q is more than 901 and r + s is more than 551, the increased number of cycles may result in finer grains in the lower layer A, which may reduce wear resistance. It is more preferable that p+q is 100 to 451 and r+s is 50 to 180.

[0049] The A1α layer and the A1β layer, and the A2γ layer and the A2δ layer may be alternately laminated, and the layer on the substrate side and the layer on the tool surface side may be either one.

[0050] 2 .Top layer The upper layer is the same as that described in the first embodiment.

[0051] 3 Other layers The outermost layer and the underlayer are the same as those described in the first embodiment. With regard to layers that are formed unintentionally (layers that may occur unavoidably), this is the same as reading lower layer A (A1α layer and A1β layer) as lower layer A1 (A1α layer and A1β layer) and lower layer A2 (A2γ layer and A2δ layer).

[0052] 4 .Substrate The material and shape of the substrate may be the same as those in the first embodiment.

[0053] III. Measurement Method 1. Average composition and thickness of the lower layer A, upper layer B, and other layers The average thickness of the lower layer A, lower layer A1, lower layer A2, upper layer B, and other layers that make up the coating layer can be determined by observing a longitudinal cross section (a cross section perpendicular to the surface of the insert, assuming that the substrate surface is treated as a flat surface, ignoring minute irregularities on the surface; for axial tools such as drills, a cross section perpendicular to the axis) using an energy dispersive X-ray spectrometer (EDS) attached to a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The average content of each component in each layer was determined by performing five TEM-EDS line analyses in the thickness direction.

[0054] Here, the surface of the substrate is determined by observing this cross section, determining the interface between the substrate and the lower layer A (or lower layer A1) by element mapping, and arithmetically determining the average straight line of the roughness curve of the interface thus obtained, which is taken as the surface of the substrate.

[0055] 2. Average thickness of the A1α layer, A1β layer, A2γ layer, and A2δ layer A line scan is performed in the thickness direction of the coating layer over a length that includes at least 10 layers, preferably 50 or more, of these layers, and the averages of the maximum and minimum intensities of adjacent Ti EDS spectra are calculated. The position on the line segment where the line scan gives the average of the calculated adjacent maximum and minimum intensities is determined. The distance between the positions that include one maximum and give the adjacent average value, and the distance between the positions that include one minimum and give the adjacent average value, are the thicknesses of each layer, and these are averaged to obtain the average thickness.

[0056] IV. Manufacturing method The coating layers of the coated tools of the first and second embodiments can be manufactured using, for example, an AIP (arc ion plating) device. The target is an AIP (arc ion plating) device having a composition corresponding to the composition of the lower layer A, the lower layer A1, and the lower layer A2. l The film can be formed by using a Ti target as a target for forming the upper layer B and an AlTiSi target having a composition corresponding to the composition of the upper layer B.

[0057] The above description includes the following additional features. (Appendix 1) A surface-coated cutting tool having a substrate and a coating layer provided on the substrate, the coating layer has a lower layer A and an upper layer B on the lower layer A, the average thickness At of the lower layer A is 0.3 μm or more and 6.0 μm or less, the average thickness Bt of the upper layer B is 0.1 μm or more and 3.0 μm or less, and 2.0≦At / Bt≦5.0; The lower layer A has an alternating laminate of an A1α layer having an average thickness of αt and an A1β layer having an average thickness of βt, 0.5 nm≦αt≦4.0 nm, 0.5 nm≦βt≦4.0 nm, 0.7≦βt / αt≦1.3, The composition of the A1α layer is Al x Ti 1-x N(x is the average value of x avg However, 0.35≦x avg ≦0.55), The composition of the A1β layer is Al y Ti 1-y N(y is the average value of y avg However, 0.60≦y avg ≦0.80), 1.2≦y avg / x avg Satisfied, The composition of the upper layer B is Al a Ti 1-a-b Si b N(a) is the average value of a avg , b is the average value of b avg However, 0.35≦a avg ≦0.60, 0.00 avg ≦0.15) A surface-coated cutting tool characterized by: (Appendix 2) The lower layer A is a lower layer A1 on the substrate side and a lower layer A2 on the upper layer B side, the average thickness A1t of the lower layer A1 and the average thickness A2t of the lower layer A2 satisfy the following conditions: 0.1 μm≦A1t≦4.5 μm, 0.2 μm≦A2t≦4.0 μm, and 0.5≦A1t / A2t≦3.0; the lower layer A1 is the alternating laminate of the A1α layer and the A1β layer, The lower layer A2 is an alternating laminate of A2γ layers having an average thickness γt and A2δ layers having an average thickness δt, 1.5 nm≦γt≦8.0 nm, 1.5 nm≦δt≦8.0 nm, 0.7≦δt / γt≦1.3, 1.0<(γt+δt) / (αt+βt)≦6.0, The composition of the A2γ layer is Al z Ti 1-z N(z is the average value of z avg However, 0.30≦z avg ≦0.50),​ The composition of the A2δ layer is Al w Ti 1-w N(w is the average value of w avg However, 0.55≦w avg ≦0.75), 1.2≦w avg / z avg Satisfied, And 0.02≦(x avg -z avg )≦0.30, 0.02≦(y avg -w avg )≦0.30 2. The surface-coated cutting tool according to claim 1, (Appendix 3) 3. The surface-coated cutting tool according to claim 1 or 2, further comprising an outermost layer on the upper layer B. (Appendix 4) 4. The surface-coated cutting tool according to any one of claims 1 to 3, further comprising a foundation layer between the lower layer A and the substrate. [Example]

[0058] Next, an example will be described. Here, as an example of the coated tool of the present invention, a coated tool having a substrate made of a WC-based cemented carbide and having an insert shape will be described. However, any of the above-mentioned materials can be used for the substrate, and as mentioned above, the same applies to shapes such as drills and end mills.

[0059] First, Co powder, TiC powder, VC powder, TaC powder, NbC powder, Cr3C2 powder, and WC powder were prepared as raw material powders. These raw material powders were blended in the proportions shown in Table 1, and wax was added. The mixture was wet mixed in a ball mill for 72 hours, dried under reduced pressure, and then pressed under a pressure of 100 MPa. These green compacts were sintered at 1400°C for 1 hour in a vacuum atmosphere of 6 Pa, and then machined to the specified dimensions to produce WC-based cemented carbide substrates 1 to 3 with the insert shape of ANSI standard SEEN42AFTN1.

[0060] Next, the substrates 1 to 3 were ultrasonically cleaned in acetone and dried. Then, to form a coating layer using an AIP device, the substrates 1 to 3 were attached along the outer periphery at a predetermined radial distance from the central axis on a rotary table in the device. In addition, a target of a predetermined composition was placed as a cathode electrode (evaporation source).

[0061] Next, the inside of the AIP device was evacuated and maintained at a vacuum of 0.1 Pa or less. The inside of the device was then heated to 600°C using a heater. After that, a DC bias voltage of -1000 V was applied to the substrate rotating on the rotating table, and a current of 100 A was passed between the cathode and anode electrodes to bombard the surface of the substrate.

[0062] <Example corresponding to the first embodiment> The AIP apparatus was filled with a nitrogen atmosphere as a reactive gas with a partial pressure of 2.6 to 7.5 Pa as shown in Table 2, and the furnace temperature was maintained at the same temperature as shown in Table 2. A DC voltage of -40 to -125 V as shown in Table 2 was applied to the substrate rotating on the rotating table, and a current of 125 to 210 A was passed between the AlTi alloy electrode for forming the lower layer A (A1α layer, A1β layer) and the anode electrode to generate an arc discharge, thereby forming A1α layer and A1β layer of the specified thickness.

[0063] Then, the deposition of the A1α layer and the A1β layer was repeated a predetermined number of times to obtain a predetermined number of laminated lower layers A.

[0064] Next, in a nitrogen atmosphere with a partial pressure of 0.4 to 0.6 Pa shown in Table 2, a DC voltage of −40 to −120 V shown in Table 2 was applied to the substrate. l An arc discharge was generated by passing a current of 120 to 220 A between the TiSi alloy and the anode electrode to form an upper layer B of a predetermined thickness, thereby obtaining coated tools of examples (hereinafter referred to as Examples) 1 to 9.

[0065] <Example corresponding to the second embodiment> The AIP apparatus contained a nitrogen atmosphere as the reactive gas with a partial pressure of 1.0 to 8.2 Pa as shown in Table 4, and the furnace temperature was maintained at the same temperature as shown in Table 4. A DC voltage of -30 to -120 V as shown in Table 2 was applied to the substrate rotating on the rotating table, and a current of 100 to 230 A was passed between the AlTi alloy electrode for forming the lower layer A1 (A1α layer, A1β layer) and the anode electrode to generate an arc discharge, thereby forming A1α layer and A1β layer of the specified thickness.

[0066] Then, the deposition of the A1α layer and the A1β layer was repeated a predetermined number of times to obtain a predetermined number of layers of the lower layer A1.

[0067] Next, in a nitrogen atmosphere with a partial pressure of 3.2 to 7.5 Pa as shown in Table 4, a DC voltage of -60 to -135 V was applied, and a current of 115 to 250 A was passed between the AlTi alloy electrode for forming the lower layer A2 (A2γ layer, A2δ layer) and the anode electrode to generate an arc discharge, thereby forming A2γ layer and A2δ layer of the specified thickness.

[0068] Then, the deposition of the A2γ layer and the A2δ layer was repeated a predetermined number of times to obtain a predetermined number of laminated lower layers A2.

[0069] Next, in a nitrogen atmosphere with a partial pressure of 2.5 to 7.7 Pa as shown in Table 4, a DC voltage of -45 to -180 V as shown in Table 2 was applied to the substrate, and a current of 125 to 200 A was passed between the AlTiSi alloy for forming the upper layer B and the anode electrode to generate an arc discharge, thereby forming an upper layer B of a predetermined thickness, thereby obtaining Examples 11 to 19.

[0070] Furthermore, in some examples corresponding to the first and second embodiments, a nitrogen atmosphere with a partial pressure of 0.5 to 9.0 Pa was used as the reactive gas in the AIP apparatus, and the temperature inside the furnace was maintained at 300 to 600°C. A DC voltage of -20 to -500 V was applied to the substrate rotating on the turntable, and a current of 50 to 250 A was passed between the Ti electrode for forming the outermost layer and the anode electrode to generate an arc discharge, thereby forming a TiN layer as the outermost layer with a predetermined thickness (the film formation conditions for the outermost layer are shown in Table 6). These examples are shown in Tables 7 and 8.

[0071] On the other hand, for comparison, using the same film-forming apparatus as above, coating layers were vapor-deposited on the substrates 1 to 3 under the conditions shown in Table 3 for the comparative examples corresponding to the first embodiment, and under the conditions shown in Table 5 for the comparative examples corresponding to the second embodiment, to produce coated tools 1 to 9 and 11 to 19 of the comparative examples shown in Tables 7 and 8 (hereinafter referred to as "comparative examples"). In some comparative examples corresponding to the first and second embodiments, a TiN layer was formed as the outermost layer, similar to the examples.

[0072] The average thickness and average composition of the coating layer were determined by cross-sectional observation using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an energy dispersive X-ray spectrometer (EDS) for longitudinal sections of the coating layer perpendicular to the surface of the substrate of Examples 1 to 9, 11 to 19 and Comparative Examples 1 to 9, 11 to 19 prepared above, with a field of view set to include the entire thickness region of the coating layer and with a width of 10 μm parallel to the surface of the substrate.

[0073] Specifically, the average thickness of the lower layer A and the upper layer B was calculated by magnifying the longitudinal cross section (observation cross section) 5,000 times and determining the film thickness at five points. When the average thickness of the lower layer A and the upper layer B was 1 μm or less, the longitudinal cross section (observation cross section) was magnified 10,000 times and determining the film thickness at five points to calculate the average thickness. The average thickness of each layer constituting the alternating laminate and the average content of each component in each layer were measured using the methods described above.

[0074] [Table 1]

[0075] [Table 2]

[0076] [Table 3]

[0077] In Table 3, "-" indicates that there is no applicable item.

[0078] [Table 4]

[0079] [Table 5]

[0080] [Table 6]

[0081] [Table 7]

[0082] In Table 7, "-" indicates that there is no applicable item.

[0083] [Table 8]

[0084] In Table 8, "-" indicates that there is no applicable item.

[0085] Next, cutting tests 1 to 3 were carried out on Examples 1 to 9, 11 to 19 and Comparative Examples 1 to 9, 11 to 19 under the following cutting conditions.

[0086] Cutting test 1 Cutting conditions: Workpiece: 60mm wide x 200mm long block material (SUS304) Cutting speed: 160 m / min. Cutout: 1.5 mm Feed: 0.10 mm / tooth. The cutting length was 2.0 m, the flank wear width was measured, and the cutting edge wear state was observed. Since the flank wear width includes the wear width due to oxidation damage and boundary damage, it can also be evaluated whether oxidation damage and boundary damage were suppressed. The results of the cutting tests are shown in Tables 9 and 10.

[0087] Cutting test 2 Cutting conditions: Workpiece: 60mm wide x 200mm long block material (made of FC■450) Cutting speed: 180 m / min. Cutout: 1.2 mm Feed: 0.10 mm / tooth. The cutting was continued up to a cutting length of 10.0 m, the flank wear width was measured, and the state of wear on the cutting edge was observed. The results of the cutting tests are shown in Tables 11 and 12.

[0088] Cutting test 3 Cutting conditions: Workpiece: 60mm wide x 200mm long block material (made of SNCM435) Cutting speed: 200 m / min. Cutout: 1.2 mm Feed: 0.10 mm / tooth. The cutting was continued up to a cutting length of 10.0 m, the flank wear width was measured, and the state of wear on the cutting edge was observed. The results of the cutting tests are shown in Tables 13 and 14.

[0089] [Table 9]

[0090] In Table 9, "*" indicates the time (seconds) until the end of the service life, since the service life was reached before the maximum cutting length was reached.

[0091] [Table 10]

[0092] [Table 11]

[0093] [Table 12]

[0094] [Table 13]

[0095] [Table 14]

[0096] The results in Tables 9 to 14 show that in all of Examples 1 to 9 and 11 to 19, no abnormal damage such as chipping or peeling occurred, and both the wear resistance and chipping resistance were excellent. In contrast to this, it is clear that Comparative Examples 1 to 9 and 11 to 19 reached the end of their life in a short period of time due to the occurrence of chipping or the progression of flank wear.

[0097] The above-disclosed embodiments are merely illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not by the above-disclosed embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0098] 1 Base 2 Covering layer 3 Lower layer A 4 Upper layer B 5 Lower Layer A1 6 Lower layer A2 7 A1α layer 8 A1β layer 9 A2γ layer 10 A2δ layer

Claims

1. A surface-coated cutting tool having a substrate and a coating layer provided on the substrate, the coating layer has a lower layer A and an upper layer B on the lower layer A, the average thickness At of the lower layer A is 0.3 μm or more and 6.0 μm or less, the average thickness Bt of the upper layer B is 0.1 μm or more and 3.0 μm or less, and 2.0≦At / Bt≦5.0; The lower layer A has an alternating laminate of an A1α layer having an average thickness αt and an A1β layer having an average thickness βt, 0.5 nm≦αt≦4.0 nm, 0.5 nm≦βt≦4.0 nm, 0.7≦βt / αt≦1.3, The composition of the A1α layer is Al ｘ Ti １－ｘ N (the average value of x) ａｖｇ However, 0.35≦x ａｖｇ ≦0.55), The composition of the A1β layer is Al ｙ Ti １－ｙ N (the average value of y ａｖｇ However, 0.60≦y ａｖｇ ≦0.80), 1.2≦y ａｖｇ / x ａｖｇ Satisfied, The composition of the upper layer B is Al ａ Ti １－ａ－ｂ Si ｂ N (the average value of a) ａｖｇ , b, which is the average value of b ａｖｇ However, 0.35≦a ａｖｇ ≦0.60, 0.00<b ａｖｇ ≦0.15) A surface-coated cutting tool characterized by:

2. The lower layer A is a lower layer A1 on the substrate side and a lower layer A2 on the upper layer B side, the average thickness A1t of the lower layer A1 and the average thickness A2t of the lower layer A2 satisfy the following conditions: 0.1 μm≦A1t≦4.5 μm, 0.2 μm≦A2t≦4.0 μm, and 0.5≦A1t / A2t≦3.0; the lower layer A1 is the alternating laminate of the A1α layer and the A1β layer, The lower layer A2 is an alternating laminate of A2γ layers having an average thickness γt and A2δ layers having an average thickness δt, 1.5 nm≦γt≦8.0 nm, 1.5 nm≦δt≦8.0 nm, 0.7≦δt / γt≦1.3, 1.0<(γt+δt) / (αt+βt)≦6.0, The composition of the A2γ layer is Al ｚ Ti １－ｚ N (the average value of z) ａｖｇ However, 0.30≦z ａｖｇ ≦0.50), The composition of the A2δ layer is Al ｗ Ti １－ｗ N (the average value of w ａｖｇ However, 0.55≦w ａｖｇ ≦0.75), 1.2≦w ａｖｇ / z ａｖｇ Satisfied, And 0.02≦(x ａｖｇ -z ａｖｇ )≦0.30, 0.02≦(y ａｖｇ -w ａｖｇ )≦0.30 2. The surface-coated cutting tool according to claim 1.

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