Surface-coated cutting tools

Abstract

A coating tool has a lower layer A with an average thickness At of 0.3–6.0 μm and an upper layer B with an average thickness Bt of 0.1–3.0 μm, where 2.0 ≤ At / Bt ≤ 5.0. The lower layer A is an alternating stack of Alα layers with an average thickness αt and Alβ layers with an average 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 Alα layer is composed of Al... x Ti 1‑x N(x average x) avg For 0.35≤x avg ≤0.55), the composition of the Alβ layer is Al y Ti 1‑y N(y average value y) avg 0.60≤y avg ≤0.80), 1.2≤y avg / x avg The upper layer B is composed of Al a Ti 1‑a‑b Si b N(a average a) avg The average value of b avg For 0.35≤a avg ≤0.60, 0.00<b avg ≤0.15).

Description

Technical Field

[0001] This invention relates to surface-coated cutting tools (hereinafter, sometimes referred to as coating tools). This application claims priority to Japanese Patent Application No. 2022-45633, filed March 22, 2022. The entire contents of that Japanese patent application are incorporated herein by reference. Background Technology

[0002] Coating tools have long been known as having a coating layer formed on a substrate such as tungsten carbide (hereinafter referred to as WC)-based cemented carbide.

[0003] Furthermore, a scheme was proposed to obtain a coated tool with further improved cutting performance by adjusting the composition and layer structure of the coating layer.

[0004] For example, Patent Document 1 describes a coating tool that has the function of coating Ti x Al 1-x N and Ti y Al 1- y The two layers N (0≤x<0.5, 0.5<y≤1) are alternately repeated to form a laminate, and the overall composition of the laminate is stoichiometrically an aluminum-rich coating. This coated tool has excellent wear resistance and damage resistance.

[0005] Additionally, for example, Patent Document 2 describes a coating tool whose coating layer includes alternating layers, each with a thickness of 2 nm or more and 100 nm or less, comprising one or more first layers and one or more second layers, wherein the first layer is composed of 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), the second layer is composed of 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), 0.05≤da≤0.2 and 0.05≤be≤0.2, the tool life of the coated tool is improved.

[0006] Furthermore, for example, Patent Document 3 describes a coating tool with a coating layer whose nanobeam diffraction pattern is indexed as a WC crystal structure. The coating layer has an a layer composed of carbides containing W and Ti and interlayers disposed on the a layer. The thickness of the a layer is 1 nm or more and 10 nm or less. The interlayers are formed by alternating b and c layers. The b layer is composed of Al and Ti nitrides or carbonitrides with an Al content ratio (atomic %) relative to the total amount of metal elements of 50% or more and 70% or less. The c layer is composed of Al and Ti nitrides or carbonitrides with an Al content ratio (atomic %) relative to the total amount of metal elements of 70% or more. The difference in Al content ratio (atomic %) between the b layer and the c layer is 10% or more and 30% or less. This coating tool also exhibits excellent durability in the cutting of stainless steel.

[0007] Furthermore, for example, Patent Document 4 describes a coating tool in which the outermost layer of the coating layer is a film composed of hexagonal nitride or carbonitride, wherein the hexagonal nitride or carbonitride is composed of Al of 60% or more and 80% or less and Si of 5% or more and 10% or less in terms of atomic percentage of metal composition, and the remainder is composed of Ti. This coating tool has durability.

[0008] Patent Document 1: Japanese Patent Publication No. Hei 7-97679

[0009] Patent Document 2: Japanese Patent Publication No. 2017-193004

[0010] Patent Document 3: Japanese Patent Publication No. 2015-110259

[0011] Patent Document 4: Japanese Patent Publication No. 2017-185551 Summary of the Invention

[0012] The present invention was made in view of the above circumstances and the above solution, and its object is to provide a cutting tool that has excellent wear resistance not only for high-speed cutting of steel or cast iron, but also for high-speed cutting of stainless steel and the like.

[0013] Here, high-speed cutting refers to cutting processes with a cutting speed that is more than 30% faster than that of ordinary cutting processes.

[0014] Regarding the surface-coated cutting tools involved in the embodiments of the present invention.

[0015] It has a matrix and a coating layer disposed on the matrix.

[0016] The coating layer has a lower layer A and an upper layer B on the lower layer A.

[0017] The lower layer A has an average thickness At of 0.3 μm or more and 6.0 μm or less, and the upper layer B has an average thickness Bt of 0.1 μm or more and 3.0 μm or less, where 2.0 ≤ At / Bt ≤ 5.0.

[0018] The lower layer A has alternating layers of A1α with an average thickness of αt and A1β with an average thickness of βt.

[0019] 0.5nm≤αt≤4.0nm, 0.5nm≤βt≤4.0nm, 0.7≤βt / αt≤1.3,

[0020] The Alα layer is composed of Al x Ti 1-x N(x average x) avg For 0.35≤x avg ≤0.55),

[0021] The Alβ layer is composed of Al y Ti 1-y N(y average value y) avg 0.60≤y avg ≤0.80),

[0022] Satisfying 1.2≤y avg / x avg ,

[0023] The upper layer B is composed of Al a Ti 1-a-b Si b N(a average a) avg The average value of b avg 0.35≤a avg ≤0.60, 0.00<b avg ≤0.15).

[0024] The surface coating cutting tool described in the foregoing embodiments can also satisfy the following requirements.

[0025] The lower layer A consists of the lower layer A1 on the substrate side and the lower layer A2 on the upper layer B side.

[0026] The average thickness A1t of the lower layer A1 and the average thickness A2t of the lower layer A2 are 0.1μm≤A1t≤4.5μm, 0.2μm≤A2t≤4.0μm, and 0.5≤A1t / A2t≤3.0, respectively.

[0027] The lower layer A1 is an alternating stack of the A1α layer and the A1β layer.

[0028] The lower layer A2 is an alternating stack of A2γ layers with an average thickness of γt and A2δ layers with an average thickness of δt.

[0029] 1.5nm≤γt≤8.0nm, 1.5nm≤δt≤8.0nm, 0.7≤δt / γt≤1.3,

[0030] 1.0<(γt+δt) / (αt+βt)≤6.0,

[0031] The composition of the A2γ layer is Al z Ti 1-z N(z average z) avg For 0.30≤z avg ≤0.50),

[0032] The A2δ layer is composed of Al w Ti 1-w N(w average w) avg For 0.55≤w avg ≤0.75),

[0033] Satisfying 1.2≤w avg / z avg ,

[0034] And 0.02≤(x) avg -z avg )≤0.30、0.02≤(y avg -w avg )≤0.30.

[0035] The surface-coated cutting tool is not only used for high-speed cutting of steel or cast iron, but also exhibits excellent wear resistance for high-speed cutting of stainless steel. Attached Figure Description

[0036] Figure 1 This is an example of a schematic diagram of a longitudinal section of the coating layer in a surface-coated cutting tool according to an embodiment of the present invention.

[0037] Figure 2 This is an example of a schematic diagram of a longitudinal section of the coating layer in a surface-coated cutting tool according to another embodiment of the present invention. Detailed Implementation

[0038] In order to obtain a cutting tool that exhibits excellent wear resistance in high-speed cutting of stainless steel and other materials while maintaining performance in machining of guaranteed steel or cast iron, the inventors conducted in-depth research on the coating layer. The results yielded the following insights (1) to (3).

[0039] (1) If an AlTiN layer with high Al content and low Al content, with an average thickness of 0.5–4.0 nm, is used as a coating layer, the hardness increases due to the decomposition of AlTiN during machining (presumably AlTiN decomposes into TiN and AlN), resulting in a coated tool with excellent wear resistance for cutting steel or cast iron. However, its performance is sometimes not fully realized when oxidative wear occurs. That is, AlTiN stacks with only different Al contents sometimes experience reduced wear resistance due to oxidative damage.

[0040] (2) Therefore, a TiSiN layer was placed on top of the AlTiN stack to suppress the aforementioned oxidative wear of the coating layer. However, due to the low oxidation resistance of the TiSiN layer, damage caused by boundary damage can occur, for example, during the machining of stainless steel. Furthermore, the lattice constants of the TiSiN layer and the AlTiN layer differ significantly, and the integration at the interface between the two layers is poor.

[0041] (3) On the other hand, even if the above-mentioned AlTiN stack is replaced to form a TiAlSiN stack with different Si content, the wear resistance will be reduced because it is difficult for TiAlSiN to decompose in the TiAlSiN stack (it is presumed that TiAlSiN decomposes into TiN, AlN and Si3N4) and the improvement in wear resistance is small.

[0042] Therefore, the inventors further discovered that if a layer consisting of alternating layers of AlTiN with two Al contents having an average thickness of 0.5 to 4.0 nm and an upper AlTiN layer containing Si, namely an AlTiSiN layer, is provided, the aforementioned objective can be achieved.

[0043] Furthermore, it was found that if the lower layer is set as a lower layer A1 on the substrate side and a lower layer A2 on its upper side, with the lower layer A1 being a layer formed by alternating layers of AlTiN layers with two Al contents of the aforementioned average thickness, and the lower layer A2 being a layer formed by alternating layers of AlTiN layers with two Al contents of the same average thickness of 1.5 to 8.0 nm, and with 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, the aforementioned objective can be achieved more reliably.

[0044] The coating tool according to embodiments of the present invention will now be described in more detail. Furthermore, in this specification and claims, when "L to M" is used to represent a numerical range, it has the same meaning as "above L and below M," and the range includes the values ​​of the upper limit value M and the lower limit value L. Additionally, when only the unit of the upper limit value M is described, the units of the upper limit value M and the lower limit value L are the same.

[0045] I. First Implementation Method

[0046] The coating tool according to the first embodiment will now be described.

[0047] 1. Coating layer

[0048] The layer structure of the coating layer of the coating tool according to the first embodiment of the present invention is as follows: Figure 1 As illustrated in the schematic example, the covering layer 2 has a lower layer A (3) on the substrate 1, and an upper layer B (4) is located above the lower layer A (3). Figure 1 In the middle, the lower layer A(3) is preferably a stack of thin layers with an average thickness of 0.5 to 4.0 nm, i.e., an alternating stack of Alα layer 7 and Alβ layer 8. Furthermore, in Figure 1 In the middle, the white base part of the lower layer A(3) is also alternately layered with A1α layer 7 and A1β layer 8.

[0049] In addition, the covering layer may have other layers, which will be described later, on top of these layers.

[0050] (1) The sum of the average thickness of the lower layer A and the average thickness of the upper layer B

[0051] 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 the thickness is less than 0.4 μm, excellent wear resistance cannot be achieved during long-term use; on the other hand, if the thickness is greater than 9.0 μm, the grains tend to coarsen, and the improvement in chipping resistance cannot be obtained. More preferably, the average thickness is 0.8 μm or more and 6.0 μm or less.

[0052] (2) The average thickness of the lower layer A and the upper layer B respectively

[0053] Preferably, 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 2.0 ≤ At / Bt ≤ 5.0. The reason for this is that if the average thickness At of the lower layer A and the average thickness Bt of the upper layer B are within these ranges, oxidation damage to the coating layer during cutting can be suppressed, and the decomposition of TiAlN in the lower layer A into TiN and AlN can improve wear resistance.

[0054] More preferably, the average thickness At of the lower layer A is 0.6 μm or more and 4.0 μm or less, and the average thickness Bt of the upper layer B is 0.2 μm or more and 2.0 μm or less. Furthermore, more preferably, 2.3 ≤ At / Bt ≤ 3.5.

[0055] In addition, 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 AlTiN decomposition during machining (AlTiN decomposes into TiN and AlN), resulting in increased hardness and improved wear resistance of the coating layer.

[0056] (3) Composition of the lower layer A

[0057] The lower layer A is an alternating stack of A1α and A1β layers. Furthermore, it is preferable that the average thicknesses αt and βt of the A1α and A1β layers respectively satisfy the following relationships: 0.5nm ≤ αt ≤ 4.0nm, 0.5nm ≤ βt ≤ 4.0nm, and 0.7 ≤ βt / αt ≤ 1.3. More preferably, they satisfy 0.8nm ≤ αt ≤ 3.5nm, 0.8nm ≤ βt ≤ 3.5nm, and 0.8 ≤ βt / αt ≤ 1.2.

[0058] The reason is that if these average thickness relationships are satisfied, the aforementioned objectives can be achieved.

[0059] (3-1) Number of stacked layers A1α and A1β

[0060] If the number of Alα layers is set to m and the number of Alβ layers is set to n, then |mn| ≤ 1. There is no particular restriction on m+n, but it is preferably 50 to 2001. The reason is that if it is less than 50, it cannot adequately prevent the propagation of cracks generated during machining, so the wear resistance may sometimes decrease. If it is greater than 2001, the number of repetitions increases, resulting in grain micronization of the lower Al layer, which may sometimes lead to a decrease in wear resistance. m+n is more preferably 100 to 1001.

[0061] In addition, the A1α layer and the A1β layer can be stacked alternately, and the layers on the substrate side and the tool surface side can be any number of layers.

[0062] (3-2) Composition of Alα and Alβ layers

[0063] The preferred compositions of the lower A1α and A1β layers are as follows:

[0064] The A1α layer is Al x Ti 1- xN(the average value of x) avg For 0.35≤x avg ≤0.55),

[0065] The A1β layer is Al y Ti 1-y N(y average value y) avg 0.60≤y avg ≤0.80),

[0066] Satisfying 1.2≤y avg / x avg .

[0067] If the composition of the Alα and Alβ layers falls within this range, the wear resistance will improve. This is presumably because AlTiN decomposes into TiN and AlN during machining.

[0068] Furthermore, regarding the AlTiN constituting the lower layer, according to one example of the manufacturing method described later, it is manufactured with a (AlTi) to N ratio of 1:1, but sometimes, unavoidably (unintentionally), the ratio is not 1:1. The same applies to other nitrides described below.

[0069] (4) Composition of the upper layer B

[0070] The preferred upper layer B is Al. a Ti 1-a-b Si b N(a average a) avg The average value of b avg 0.35≤a avg ≤0.60, 0.00<b avg ≤0.15).

[0071] If the composition of the upper layer B is within the above range, it can improve oxidation resistance and wear resistance; however, if it is outside this range, it leads to a decrease in oxidation resistance and wear resistance. The reason for this is presumably due to the precipitation of a hexagonal AlN phase.

[0072] (5) Other layers

[0073] (5-1) Layers that can be intentionally formed into films

[0074] Examples of layers that can be intentionally formed into films include the outermost layer and the base layer, as described below.

[0075] (5-1-1) Outermost layer

[0076] The outermost layer can be selectively set on the upper layer B.

[0077] As the outermost layer, a TiN layer may be provided, for example (the atomic ratio of Ti to N in the TiN layer is not limited to stoichiometry). With this TiN layer present, since the TiN layer itself has a golden hue, it can be used, for example, as a recognition layer to determine whether the coating tool has been used or not based on hue changes. Furthermore, the average thickness of the TiN layer serving as the recognition layer can be, for example, 0.1 to 1.0 μm.

[0078] (5-1-2) Basal layer

[0079] A base layer can be selectively disposed between the lower layer A and the substrate.

[0080] Examples of substrate layers include TiC layers, TiN layers, TiCN layers, TiCNO layers, Ti compound layers, and AlTiN layers, with an average thickness of 0.1–2.0 μm. If the average thickness is within this range, the adhesion between the lower layer A and the substrate may be further improved.

[0081] (5-2) Unintentionally formed film layers (layers that may inevitably form)

[0082] In this embodiment, film formation is performed without a base layer, lower layer A (A1α layer and A1β layer), upper layer B, and any layer other than the outermost layer; that is, film formation is performed with these layers in contact with each other. However, when the types of layers to be formed are changed, unintentional changes in pressure and temperature within the membrane apparatus may occur, sometimes resulting in unintentional formation of layers different from these layers.

[0083] 2. Matrix

[0084] (1) Material

[0085] If the substrate used in this embodiment is a material of a conventionally known substrate, any material can be used as long as it does not hinder the achievement of the aforementioned objective. For example, WC-based cemented carbide (which includes Co in addition to WC, and further includes alloys made by adding carbides or carbonitrides such as Ti, Ta, and Nb), cermet (ceramics with TiC, TiN, TiCN, etc. as the main components), ceramic (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, alumina), cBN sintered body, or diamond sintered body are preferred.

[0086] (2) Shape

[0087] There are no particular restrictions on the shape of the substrate as long as it is used as a cutting tool; examples include the shape of a cutting blade and the shape of a drill bit.

[0088] II. Second Implementation Method

[0089] The second embodiment will be described. Descriptions that overlap with those of the first embodiment will be omitted.

[0090] 1. Coating layer

[0091] The layer structure of the coating layer of the coating tool involved in the second embodiment is as follows: Figure 2 As illustrated in the schematic example, the covering layer 2 has a lower layer A (3) on the substrate 1, and an upper layer B (4) is located above the lower layer A (3). In the lower layer A (3), lower layers A1 (5) and A2 (6) are stacked. Figure 2 In the preferred embodiment, the lower layer A1(5) is the same as in the first embodiment, and the lower layer A2(6) is an alternating stack of thin layers with an average thickness of 1.5 to 8.0 nm, that is, the lower layer A1(5) is an alternating stack of A1α layer 7 and A1β layer 8, and the lower layer A2(6) is an alternating stack of A2γ layer 9 and A2δ layer 10. Furthermore, in Figure 2 In the middle, the white base parts of the lower layer A1(5) and the lower layer A2(6) are also alternately stacked with A1α layer 7 and A1β layer 8, A2γ layer 9 and A2δ layer 10 respectively.

[0092] In addition, similar to the first embodiment, the covering layer may have other layers besides these layers, as described later.

[0093] (1) The sum of the average thickness of the lower layer A and the average thickness of the upper layer B

[0094] 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 the same thickness range as in the first embodiment (more preferably the same thickness range as in the first embodiment).

[0095] (2) The average thickness of the lower layer A and the upper layer B respectively

[0096] In the second embodiment, the average thickness of the lower layer A and the upper layer B is preferably the same as that in the first embodiment (more preferably the same thickness range).

[0097] (3) Composition of the lower layer A

[0098] In the second embodiment, the lower layer A comprises lower layer A1 and lower layer A2. Preferably, the average thickness A1t of lower layer A1 and the average thickness A2t of lower layer A2 are 0.1μm≤A1t≤4.5μm, 0.2μm≤A2t≤4.0μm, and 0.5≤A1t / A2t≤3.0. When this relationship is satisfied, the aforementioned objective is achieved.

[0099] The lower layers A1 and A2 will be described in detail below.

[0100] (3-1) Lower layer A1

[0101] Preferably, the lower layer A1 is an alternating stack of A1α and A1β layers, the same as the lower layer A in the first embodiment, satisfying the relationship between average thickness and average thickness described in the description of the first embodiment, and further satisfying the relationship between composition and composition.

[0102] (3-2) Lower layer A2

[0103] The lower layer A2 is an alternating stack of A2γ and A2δ layers. Preferably, the average thicknesses γt and δt of the A2γ and A2δ layers satisfy the following relationships: 1.5nm≤γt≤8.0nm, 1.5nm≤δt≤8.0nm, 0.7≤δt / γt≤1.3, and relative to the average thicknesses of the A1α and A1β layers constituting the lower layer A1, 1.0<(γt+δt) / (αt+βt)≤6.0.

[0104] The reason is that if this relation is satisfied, the aforementioned objective is achieved. More preferably, (γt+δt) / (αt+βt) is 1.2≤(γt+δt) / (αt+βt)≤3.0.

[0105] (3-3) Composition of A2γ layer and A2δ layer

[0106] The preferred composition of the A2γ layer is Al z Ti 1-z N(z average z) avg For 0.30≤z avg ≤0.50),

[0107] The A2δ layer is composed of Al w Ti 1-w N(w average w) avg For 0.55≤w avg ≤0.75),

[0108] Satisfying 1.2≤w avg / z avg .

[0109] Furthermore, the preferred compositions of the A1α and A1β layers and the A2γ and A2δ layers satisfy 0.02 ≤ (x avg -z avg )≤0.30、0.02≤(y avg -w avg )≤0.30.

[0110] If the compositions of the Al1α, Al1β, Al2γ, and Al2δ layers are within this range, the wear resistance will be improved. The reasoning is presumably that if the compositions of these layers are within this range, a lower layer A with a higher Al content can be formed. During machining, AlTiN decomposes into TiN and AlN. However, when the composition deviates from this range, the difference in Al content between the lower layers A1 and A2 becomes smaller. This decomposition is insufficient, and the strain reduction in the lower layer A1 is inadequate, leading to the precipitation of a hexagonal AlN phase, thus reducing the wear resistance of the coating layer.

[0111] (4) Average thickness and number of layers of A1α, A1β, A2γ and A2δ

[0112] Preferably, the average thickness of the A1α and A1β layers constituting the lower layers A1 and A2, respectively, is 0.5–4.0 nm, and the average thickness of the A2γ and A2δ layers is 1.5–8.0 nm. The number of stacks p of the A1α layer and q of the A1β layer in the lower layer A1, and the number of stacks r of the A2γ layer and s of the A2δ layer in the lower layer A2, are |pq|≤1 and |rs|≤1. There are no particular restrictions on p+q and r+s, but p+q is preferably 50–901 and r+s is preferably 20–551. The reason is that if p+q is less than 50 and r+s is less than 20, the propagation of cracks generated during machining cannot be sufficiently prevented, thus sometimes reducing wear resistance. On the other hand, if p+q is greater than 901 and r+s is greater than 551, the number of repetitions increases, resulting in grain micronization of the lower layer A, which sometimes leads to reduced wear resistance. More preferably, p+q is 100–451 and r+s is 50–180.

[0113] In addition, the A1α and A1β layers, and the A2γ and A2δ layers can be stacked alternately, and the layers on the substrate side and the tool surface side can be any number of layers.

[0114] 2. Upper layer

[0115] The description of the upper layer is the same as that of the first embodiment.

[0116] 3. Other layers

[0117] The description of the outermost layer and the base layer is the same as that of the first embodiment.

[0118] Regarding layers that are not intentionally formed (layers that may inevitably be formed), it is the same as the case where the lower layer A (A1α layer and A1β layer) is replaced by the lower layer A1 (A1α layer and A1β layer) and the lower layer A2 (A2γ layer and A2δ layer).

[0119] 4. Matrix

[0120] The material and shape of the substrate can be the same as those in the first embodiment.

[0121] III. Measurement Method

[0122] 1. Average composition and average thickness of lower layer A, upper layer B, and other layers.

[0123] The average thickness of the lower layers A, A1, A2, upper layer B, and other layers constituting the coating can be determined by observing longitudinal sections (perpendicular to the surface when the substrate surface is treated as a flat surface, neglecting minor irregularities, in the case of cutting tools; perpendicular to the axis in the case of shaft-type tools such as drill bits) using an energy-dispersive X-ray spectrometer (EDS) attached to a scanning electron microscope (SEM) or transmission electron microscope (TEM). The average content ratio of each component in each layer is determined by analyzing five TEM-EDS lines along the thickness direction.

[0124] Here, regarding the surface of the substrate, observe its longitudinal section, determine the interface between the substrate and the lower layer A (or lower layer A1) through element mapping, and calculate the average straight line of the roughness curve of the interface obtained in this way using an arithmetic method, and use it as the surface of the substrate.

[0125] 2. Average thickness of A1α layer, A1β layer, A2γ layer and A2δ layer

[0126] In the thickness direction of the coating layers, a line scan is performed over a length containing at least 10 layers, preferably more than 50 layers, to calculate the average of the maximum and minimum intensity values ​​of the EDS spectra of adjacent Ti layers. Positions on the line segment where the line scan was performed are identified, where the calculated average of the maximum and minimum intensity values ​​of adjacent layers is given. Furthermore, the distances between positions containing a maximum and an adjacent average value, and the distances between positions containing a minimum and an adjacent average value, are taken as the thickness of each layer. Averaging these distances yields the average thickness.

[0127] IV. Manufacturing Method

[0128] The coating layer of the coating tool in the first and second embodiments can be manufactured, for example, using an AIP (arc ion plating) apparatus. Furthermore, film deposition can be performed using an AlTi target with a composition corresponding to the compositions of the lower layers A, A1, and A2, respectively, and an AlTiSi target with a composition corresponding to the composition of the upper layer B, as the film deposition target.

[0129] The above description includes the following features.

[0130] (Postscript 1)

[0131] A surface-coated cutting tool has a substrate and a coating layer disposed on the substrate, characterized in that,

[0132] The coating layer has a lower layer A and an upper layer B on the lower layer A.

[0133] The lower layer A has an average thickness At of 0.3 μm or more and 6.0 μm or less, and the upper layer B has an average thickness Bt of 0.1 μm or more and 3.0 μm or less, where 2.0 ≤ At / Bt ≤ 5.0.

[0134] The lower layer A has alternating layers of A1α with an average thickness of αt and A1β with an average thickness of βt.

[0135] 0.5nm≤αt≤4.0nm, 0.5nm≤βt≤4.0nm, 0.7≤βt / αt≤1.3,

[0136] The Alα layer is composed of Al x Ti 1-x N(x average x) avg For 0.35≤x avg ≤0.55),

[0137] The Alβ layer is composed of Al y Ti 1-y N(y average value y) avg 0.60≤y avg ≤0.80),

[0138] Satisfying 1.2≤y avg / x avg ,

[0139] The upper layer B is composed of Al a Ti 1-a-b Si b N(a average a) avg The average value of b avg 0.35≤a avg ≤0.60, 0.00<b avg ≤0.15).

[0140] (Postscript 2)

[0141] The surface-coated cutting tool according to Appendix 1 is characterized in that,

[0142] The lower layer A consists of the lower layer A1 on the substrate side and the lower layer A2 on the upper layer B side.

[0143] The average thickness A1t of the lower layer A1 and the average thickness A2t of the lower layer A2 are 0.1μm≤A1t≤4.5μm, 0.2μm≤A2t≤4.0μm, and 0.5≤A1t / A2t≤3.0.

[0144] The lower layer A1 is an alternating stack of the A1α layer and the A1β layer.

[0145] The lower layer A2 is an alternating stack of A2γ layers with an average thickness of γt and A2δ layers with an average thickness of δt.

[0146] 1.5nm≤γt≤8.0nm, 1.5nm≤δt≤8.0nm, 0.7≤δt / γt≤1.3,

[0147] 1.0<(γt+δt) / (αt+βt)≤6.0,

[0148] The composition of the A2γ layer is Al z Ti 1-z N(z average z) avg For 0.30≤z avg ≤0.50),

[0149] The A2δ layer is composed of Al w Ti 1-w N(w average w) avg For 0.55≤w avg ≤0.75),

[0150] Satisfying 1.2≤w avg / z avg ,

[0151] And 0.02≤(x) avg -z avg )≤0.30、0.02≤(y avg -w avg )≤0.30.

[0152] (Note 3)

[0153] The surface-coated cutting tool according to Appendix 1 or 2 is characterized in that it has an outermost layer on the upper layer B.

[0154] (Postscript 4)

[0155] The surface-coated cutting tool according to any one of Appendices 1 to 3 is characterized in that a base layer is provided between the lower layer A and the substrate.

[0156] Example

[0157] Next, the embodiments will be described.

[0158] Here, as an embodiment of the coating tool of the present invention, a coating tool with a WC-based cemented carbide substrate and a blade shape is described, but the substrate can be any of the aforementioned materials. In addition, as described above, the shape can also be that of a drill bit, end mill, etc.

[0159] First, as raw material powders, Co powder, TiC powder, VC powder, TaC powder, NbC powder, Cr3C2 powder, and WC powder were prepared. These raw material powders were mixed according to the proportions shown in Table 1. Wax was further added, and the mixture was wet-mixed in a ball mill for 72 hours. After vacuum drying, the mixture was pressed into shape under a pressure of 100 MPa. The pressed compacts were sintered under a vacuum atmosphere of 6 Pa and held at 1400°C for 1 hour to produce WC-based cemented carbide substrates 1 to 3 with the blade shape of ANSI standard SEEN42AFTN1.

[0160] Next, substrates 1 to 3 are ultrasonically cleaned in acetone and then dried. Furthermore, in order to form a coating layer using an AIP apparatus, substrates 1 to 3 are mounted along their outer periphery at a predetermined distance from the central axis of the rotating stage within the apparatus, in the radial direction. Additionally, a target with a predetermined composition is configured as the cathode electrode (evaporation source).

[0161] Next, while venting the AIP device and maintaining a vacuum of less than 0.1 Pa, the device is heated to 600°C using a heater. Then, a DC bias voltage of -1000V is applied to the substrate rotating on the rotary table, and a current of 100A flows between the cathode and anode electrodes to bombard the surface of the substrate.

[0162] <Examples corresponding to the first embodiment>

[0163] The reaction gas in the AIP device is set as a nitrogen atmosphere with a partial pressure of 2.6 to 7.5 Pa as shown in Table 2, and the furnace temperature is maintained as shown in Table 2. Then, a DC bias voltage of -40 to -125 V as shown in Table 2 is applied to the substrate rotating on the aforementioned rotating table, and a current of 125 to 210 A is flowed between the AlTi alloy electrode used to form the lower layer A (Alα layer, Alβ layer) and the anode electrode to generate an arc discharge, forming Alα layer and Alβ layer of a specified thickness.

[0164] Then, the number of layers in the lower layer A is determined by repeating the film formation of the A1α layer and the A1β layer a specified number of times.

[0165] Next, under a nitrogen atmosphere with a partial pressure of 0.4 to 0.6 Pa as shown in Table 2, a DC bias voltage of -40 to -120 V as shown in Table 2 is applied to the substrate, and a current of 120 to 220 A is flowed between the AlTiSi alloy used to form the upper layer B and the anode electrode to generate an arc discharge, thereby forming a film of the upper layer B with a specified thickness, and obtaining the coating tool of the embodiments (hereinafter referred to as Embodiments) 1 to 9.

[0166] <Examples corresponding to the second implementation>

[0167] The reaction gas in the AIP device is set as a nitrogen atmosphere with a partial pressure of 1.0 to 8.2 Pa as shown in Table 4, and the furnace temperature is maintained as shown in Table 4. Then, a DC bias voltage of -30 to -120 V as shown in Table 2 is applied to the substrate rotating on the aforementioned rotating table, and a current of 100 to 230 A is flowed between the AlTi alloy electrode used to form the lower Al (Alα layer, Alβ layer) and the anode electrode to generate an arc discharge, forming Alα layer and Alβ layer of a specified thickness.

[0168] Then, the number of layers of the lower layer A1 is determined by repeating the film formation of the A1α layer and the A1β layer a specified number of times.

[0169] Next, under a nitrogen atmosphere with a partial pressure of 3.2 to 7.5 Pa as shown in Table 4, a DC bias voltage of -60 to -135 V is applied, and a current of 115 to 250 A flows between the AlTi alloy electrode used to form the lower layer A2 (A2γ layer, A2δ layer) and the anode electrode to generate an arc discharge, thereby forming the A2γ layer and A2δ layer of a specified thickness.

[0170] Then, the number of layers in the lower layer A2 is determined by repeating the film formation of the A2γ layer and the A2δ layer a specified number of times.

[0171] Next, under a nitrogen atmosphere with a partial pressure of 2.5 to 7.7 Pa as shown in Table 4, a DC bias 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 flowed between the AlTiSi alloy used to form the upper layer B and the anode electrode to generate an arc discharge, thereby forming an upper layer B of a specified thickness, resulting in Examples 11 to 19.

[0172] Furthermore, in several embodiments corresponding to the first and second embodiments, a nitrogen atmosphere with a partial pressure of 0.5 to 9.0 Pa is used as the reaction gas in the AIP device, and the furnace temperature is maintained at 300 to 600°C. Then, a DC bias voltage of -20 to -500 V is applied to the substrate rotating on the aforementioned rotating stage, and a current of 50 to 250 A flows between the Ti electrode used to form the outermost layer and the anode electrode to generate an arc discharge, thereby forming a TiN layer of a specified thickness (the film formation conditions for the outermost layer are shown in Table 6). These embodiments are shown in Tables 7 and 8.

[0173] On the other hand, for comparison purposes, for the substrates 1 to 3 described above, the same film-forming apparatus as described above was used to vapor deposit the coating layer corresponding to the first embodiment according to the conditions shown in Table 3, and the coating layer corresponding to the second embodiment was vapor deposited according to the conditions shown in Table 5. The coating tools (hereinafter referred to as "comparative examples") 1 to 9 and 11 to 19 of the comparative examples shown in Tables 7 and 8 were made.

[0174] In addition, in several comparative examples corresponding to the first and second embodiments, the outermost layer, namely the TiN layer, was formed in the same manner as in the embodiments.

[0175] Regarding the average thickness and average composition of the coating layer, 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) in a field of view with a width of 10 μm in a direction parallel to the surface of the substrate of Examples 1-9, 11-19 and Comparative Examples 1-9, 11-19, which is set to include the entire thickness region of the coating layer.

[0176] Specifically, regarding the average thickness of the lower layer A and the upper layer B, the longitudinal section used as the observation profile was magnified 5000 times to determine the film thickness at five points, and the average thickness was calculated. Furthermore, when the average thickness of the lower layer A and the upper layer B is less than 1 μm, the longitudinal section used as the observation profile was magnified 10000 times to determine the film thickness at five points, and the average thickness was calculated. Additionally, the average thickness of each layer constituting the alternating layers and the average content of each component in each layer were determined using the above method.

[0177] [Table 1]

[0178]

[0179]

[0180]

[0181]

[0182]

[0183] [Table 6]

[0184]

[0185]

[0186]

[0187] Next, cutting tests 1 to 3 were conducted on Examples 1 to 9, 11 to 19 and Comparative Examples 1 to 9, 11 to 19 under the following cutting conditions.

[0188] Cutting Test 1

[0189] Cutting conditions:

[0190] Workpiece: A block of material (made of SUS304 stainless steel) with a width of 60mm and a length of 200mm.

[0191] Cutting speed: 160 m / min.

[0192] Depth of cut: 1.5mm

[0193] Feed rate: 0.10 mm / tooth.

[0194] Cut to a cutting length of 2.0 m, measure the wear width on the flank face, and observe the wear condition of the tool tip. Since the wear width on the flank face also includes the wear width caused by oxidation damage and boundary damage, it is also possible to evaluate whether oxidation damage and boundary damage have been suppressed.

[0195] The results of the cutting tests are shown in Tables 9 and 10.

[0196] Cutting Test 2

[0197] Cutting conditions:

[0198] Workpiece: Block material, 60mm wide x 200mm long (FC■450).

[0199] Cutting speed: 180 m / min.

[0200] Cutting depth: 1.2mm.

[0201] Feed rate: 0.10 mm / tooth.

[0202] Cut to a cutting length of 10.0m, measure the wear width of the flank face, and observe the wear condition of the tool tip.

[0203] The results of the cutting tests are shown in Tables 11 and 12.

[0204] Cutting test 3

[0205] Cutting conditions:

[0206] Workpiece: Block material, 60mm wide x 200mm long (made of SNCM435)

[0207] Cutting speed: 200 m / min.

[0208] Depth of cut: 1.2mm

[0209] Feed rate: 0.10 mm / tooth.

[0210] Cut to a cutting length of 10.0m, measure the wear width of the flank face, and observe the wear condition of the tool tip.

[0211] The results of the cutting tests are shown in Tables 13 and 14.

[0212] [Table 9]

[0213]

[0214] In Table 9, “※” indicates the service life is reached before the maximum cutting length is reached, and the time (in seconds) for the service life to be reached is indicated.

[0215] [Table 10]

[0216]

[0217] [Table 11]

[0218]

[0219] [Table 12]

[0220]

[0221] [Table 13]

[0222]

[0223] [Table 14]

[0224]

[0225] According to the results in Tables 9 to 14, no abnormal damage such as chipping or peeling occurred in Examples 1 to 9 and 11 to 19, and the wear resistance and chipping resistance were excellent.

[0226] In contrast, it is clear that Comparative Examples 1-9 and 11-19 reach their lifespan in a short time due to chipping or the progression of flank wear.

[0227] The embodiments disclosed above are merely exemplary in all respects and are not restrictive. The scope of the invention is defined by the claims, not by the foregoing embodiments, and is intended to include all modifications in the same sense and scope as the claims.

[0228] Explanation of reference numerals in the attached figures

[0229] 1. Matrix

[0230] 2. Coating layer

[0231] 3 Lower layer A

[0232] 4. Upper layer B

[0233] 5 Lower layer A1

[0234] 6. Lower layer A2

[0235] 7 A1α layer

[0236] 8 A1β layers

[0237] 9 A2γ layer

[0238] 10 A2δ layer

Claims

1. A surface-coated cutting tool, comprising a substrate and a coating layer disposed thereon, characterized in that, 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 ≥0.3μm and ≤6.0μm, and the average thickness Bt of the upper layer B is ≥0.1μm and ≤3.0μm, where 2.0≤At / Bt≤5.

0. The lower layer A has alternating layers of A1α layers with an average thickness αt and A1β layers with an average thickness βt. 0.5nm≤αt≤4.0nm, 0.5nm≤βt≤4.0nm, 0.7≤βt / αt≤1.3, The Alα layer is composed of Al x Ti 1-x N, Where, the average value of x is x avg For 0.35≤x avg ≤0.55, The Alβ layer is composed of Al y Ti 1-y N, where the average value of y is y avg 0.60≤y avg ≤0.80, Satisfying 1.2≤y avg / x avg , The upper layer B is composed of Al a Ti 1-a-b Si b N, where the average value of a is a avg The average value of b avg 0.35≤a avg ≤0.60, 0.00<b avg ≤0.

15.

2. The surface-coated cutting tool according to claim 1, characterized in that, The lower layer A consists of the lower layer A1 on the substrate side and the 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 are 0.1μm≤A1t≤4.5μm, 0.2μm≤A2t≤4.0μm, and 0.5≤A1t / A2t≤3.

0. The lower layer A1 is an alternating stack of the A1α layer and the A1β layer. The lower layer A2 is an alternating stack of A2γ layers with an average thickness of γt and A2δ layers with an average thickness of δt. 1.5nm≤γt≤8.0nm, 1.5nm≤δt≤8.0nm, 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, where the average value of z is z avg For 0.30≤z avg ≤0.50, The A2δ layer is composed of Al w Ti 1-w N, where the average value of w is w avg For 0.55≤w avg ≤0.75, Satisfying 1.2≤w avg / z avg , And 0.02≤(x) avg -z avg )≤0.30、0.02≤(y avg -w avg )≤0.30.

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