Coated cutting tools

Abstract

To provide a coated cutting tool long in tool life improved in defect resistance and abrasion resistance.SOLUTION: The coated cutting tool comprises: a base material; and a coating layer formed on the surface of the base material. The coating layer includes a lower layer and an upper layer in this order from the base material side toward the surface of the coating layer. The lower layer includes one, two, or more Ti compound layers each composed of a Ti compound of Ti and at least one element selected from the group consisting of C, N, O, and B. The upper layer includes an α-type Al2O3 layer made of α-type Al2O3. The average thickness of the lower layer is 3.0 μm-15.0 μm, and the average thickness of the upper layer is 3.0 μm-15.0 μm. In the upper layer, when a range up to 1 μm from the interface of the lower layer side to the interface of the surface side of the coating layer is a lower side upper layer, and a range of the surface side of the coating layer from the lower side upper layer is an upper side upper layer, an orientation difference in the lower side upper layer satisfies a specific condition, and an orientation difference in the upper side upper layer satisfies a specific condition.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coated cutting tool.

Background Art

[0002] Conventionally, it is well known that a coated cutting tool formed by vapor-depositing a coating layer with a total film thickness of 3 to 20 μm on the surface of a substrate made of cemented carbide by chemical vapor deposition is used for cutting steel, cast iron, etc. As the above coating layer, for example, a coating layer composed of one single layer or two or more layers selected from the group consisting of carbides, nitrides, carbonitrides, carbonates, and carbonitrates of Ti and aluminum oxide (Al2O3) is known.

[0003] For example, in Patent Document 1, there is a cutting tool including a substrate and a coating film that coats the substrate. The coating film includes an α-alumina layer provided on the substrate. The α-alumina layer includes crystal grains of α-alumina. The α-alumina layer includes a lower part and an upper part. When the α-alumina layer is cut by a plane including the normal line of the second interface and the crystal orientation of each crystal grain of α-alumina is specified by electron backscatter diffraction image analysis using a field emission scanning electron microscope, and a color map is created based on this, in the color map, in the upper part, the area ratio of crystal grains of α-alumina whose normal direction of the (006) plane is within ±15° with respect to the normal direction of the second interface is 50% or more, and in the lower part, the area ratio of crystal grains of α-alumina whose normal direction of the (110) plane is within ±15° with respect to the normal direction of the second interface is 50% or more, and a cutting tool having a thickness of the α-alumina layer of 3 μm or more and 20 μm or less has been proposed.

[0004] In Patent Document 2, there is proposed a coated object having a coated object composed of at least one refractory single layer or multiple layers including a dense fine-grained layer of α-Al2O3 characterized by a controlled microstructure and phase composition having a crystal plane grown in the (012) direction.

[0005] Patent Document 3 proposes a cutting insert having an α-Al2O3 layer formed on a (Ti,Al)(C,O,N) bonded phase in which the aluminum content increases toward the outermost layer, wherein the nucleation process of α-Al2O3 includes an aluminization process and an oxidation process, the α-Al2O3 layer has a thickness in the range of 1 to 20 μm and contains columnar grains, the length / width ratio of the alumina grains is 2 to 12, and in measurements using XRD, a (012) growth texture and diffraction peaks of (104), (110), (113), and (116) are measured. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2020 / 170571 [Patent Document 2] Japanese Patent Application Publication No. 06-316758 [Patent Document 3] Japanese Patent Publication No. 2003-340610 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, machining processes have increasingly involved higher speeds, higher feed rates, and deeper cuts. Furthermore, the increased strength of workpiece materials necessitates improved chipping and wear resistance of tools compared to conventional methods. In particular, cast iron has become stronger in recent years to achieve thinner walls, and machining processes that place heavy loads on coated cutting tools, such as high-speed cutting of cast iron, are becoming more common. Under such harsh cutting conditions, conventional coated cutting tools, such as those described in Patent Documents 1-3, may suffer from chipping or wear due to insufficient mechanical strength and / or peel resistance of the alumina layer.

[0008] This invention has been made in view of the above circumstances, and aims to provide a coated cutting tool with improved fracture resistance and wear resistance, resulting in a longer tool life. [Means for solving the problem]

[0009] The inventors conducted extensive research on extending the tool life of coated cutting tools and discovered that by configuring coated cutting tools in a specific way, it is possible to improve their fracture resistance and wear resistance, thereby extending the tool life of coated cutting tools. This led to the completion of the present invention.

[0010] In other words, the gist of this invention is as follows: [1] A coated cutting tool comprising a base material and a coating layer formed on the surface of the base material, The coating layer includes a lower layer and an upper layer in this order, from the substrate side toward the surface of the coating layer. The lower layer comprises one or more Ti compound layers, each consisting of a Ti compound made of Ti and at least one element selected from the group consisting of C, N, O, and B, and the upper layer comprises an α-type Al2O3 layer made of α-type Al2O3. The average thickness of the lower layer is 3.0 μm or more and 15.0 μm or less. The average thickness of the upper layer is 3.0 μm or more and 15.0 μm or less. In the upper layer, if the area from the interface on the lower layer side (however, if there are irregularities on the interface, the position closest to the surface of the coating layer) to the interface on the surface side of the coating layer is defined as the lower upper layer, and the area closer to the surface of the coating layer than the lower upper layer is defined as the upper upper layer, In the aforementioned lower upper layer, the following condition expressed by formula (1) is satisfied, 40 ≤ RSA1 ≤ 80 (1) (In formula (1), RSA1 is the ratio (in area %) of the cross-sectional area of ​​particles in the lower upper layer in a direction perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (110) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100 area %). In the upper upper layer, the following conditions are met, as shown in equation (2): 50 ≤ RSB2 ≤ 90 (2) (In formula (2), RSB2 is the ratio (in area %) of the cross-sectional area of ​​particles in the upper upper layer in a direction perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (012) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100 area %). Coated cutting tools. [2] In the aforementioned lower upper layer, the following conditions are met, as expressed by equation (3): 0 <RSB1≦20 (3) (In formula (3), RSB1 is the ratio (in area %) of the cross-sectional area of ​​particles in the lower upper layer in a direction perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (012) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100 area %). [1] The coated cutting tool described above. [3] In the upper upper layer, the following conditions are met, as shown in equation (4): 0 ≤ RSA2 ≤ 10 (4) (In formula (4), RSA2 is the ratio (in area %) of the cross-sectional area of ​​particles in the upper upper layer in a direction perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (110) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100 area %). A coated cutting tool as described in [1] or [2]. [4] In the upper layer, the average particle size of the particles in a direction parallel to the surface of the substrate at a position 0.5 μm from the interface on the lower layer side toward the surface of the coating layer is defined as the first average particle size. In the upper layer, if the average particle size of the particles in a direction parallel to the surface of the substrate at a position 1.0 μm from the interface opposite to the substrate toward the interface on the substrate side is defined as the second average particle size, The ratio of the second average particle size to the first average particle size is 1.0 or more and 2.0 or less. The coated cutting tool according to any one of [1] to [3]. [5] The first average particle size is 0.3 μm or more and 0.5 μm or less, The coated cutting tool according to [4]. [6] The second average particle size is 0.3 μm or more and 1.0 μm or less, The coated cutting tool according to [4] or [5]. [7] The average thickness of the coating layer is 6.0 μm or more and 30.0 μm or less, The coated cutting tool according to any one of [1] to [6]. [Advantages of the Invention]

[0011] According to the present invention, it is possible to provide a coated cutting tool with a long tool life that has improved chipping resistance and wear resistance. [Brief Description of the Drawings]

[0012] [Figure 1] It is a schematic diagram showing an example of the coated cutting tool of the present invention. [Embodiments for Carrying Out the Invention]

[0013] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail, but the present invention is not limited to the following present embodiment. The present invention can be variously modified without departing from the gist thereof. In the drawings, the same reference numerals are assigned to the same elements, and redundant explanations are omitted. In addition, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0014] [Coated Cutting Tool] The coated cutting tool of this embodiment comprises a base material and a coating layer formed on the surface of the base material, wherein the coating layer includes a lower layer and an upper layer in that order, from the base material side toward the surface of the coating layer, the lower layer includes one or more Ti compound layers made of Ti and at least one element selected from the group consisting of C, N, O and B, the upper layer includes an α-type Al2O3 layer made of α-type Al2O3, the average thickness of the lower layer is 3.0 μm or more and 15.0 μm or less, the average thickness of the upper layer is 3.0 μm or more and 15.0 μm or less, in the upper layer, the range from the interface on the lower layer side (however, if there are irregularities on the interface, the position closest to the surface of the coating layer) toward the interface on the surface side of the coating layer is defined as the lower upper layer, and the range on the surface side of the coating layer than the lower upper layer is defined as the upper upper layer, the lower upper layer satisfies the condition represented by the following formula (1), and the upper upper layer satisfies the condition represented by the following formula (2). 40 ≤ RSA1 ≤ 80 (1) (In formula (1), RSA1 is the ratio (in area %) of the cross-sectional area of ​​particles in the lower upper layer in a direction perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (110) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100 area %). 50 ≤ RSB2 ≤ 90 (2) (In formula (2), RSB2 is the ratio (in area %) of the cross-sectional area of ​​particles in the upper upper layer perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (012) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100 area %).

[0015] The factors that contribute to the improved chipping resistance and wear resistance of such coated cutting tools, resulting in longer tool life, are not fully understood, but are presumed to be as follows. However, the factors are not limited to those listed below. If the average thickness of the lower layer having the above composition is 3.0 μm or more, it exhibits excellent abrasion resistance and resistance to plastic deformation. If it is 15.0 μm or less, peeling of the coating layer is suppressed, resulting in excellent chipping resistance and fracture resistance. Furthermore, if the average thickness of the upper layer having the above composition is 3.0 μm or more, crater wear is suppressed, resulting in excellent abrasion resistance and resistance to plastic deformation. If it is 15.0 μm or less, the adhesion between the lower and upper layers is improved, resulting in excellent chipping resistance and fracture resistance. In the aforementioned lower upper layer, if RSA1 accounts for 40% or more of the area, adhesion to the lower layer is improved, thereby improving chipping resistance and fracture resistance. Furthermore, if RSA1 accounts for 80% or less of the area, the formation of the lower upper layer becomes easier. Moreover, in the aforementioned upper upper layer, if RSB2 accounts for 50% or more of the area, mechanical strength is improved, thereby improving fracture resistance. Furthermore, if RSB2 accounts for 90% or less of the area, the formation of the upper upper layer becomes easier. The combined effects described above result in a coated cutting tool of this embodiment that offers improved fracture resistance and wear resistance, leading to a longer tool life.

[0016] Figure 1 is a schematic cross-sectional view partially showing an example of a coated cutting tool according to this embodiment. The coated cutting tool 5 has a base material 1 and a coating layer 4 formed on the surface of the base material 1. In the coating layer 4, a lower layer 2 and an upper layer 3 are stacked upwards in this order from the base material 1 side. The upper layer 3 includes a lower upper layer 3a in the range from the lower layer 2 side toward the surface of the coating layer 4 up to 1 μm, and includes an upper upper layer 3b in the range toward the surface of the coating layer 4 beyond the lower upper layer 3a.

[0017] The base material in this embodiment is not particularly limited as long as it can be used as a base material for a coated cutting tool. Examples of such base materials include cemented carbide, cermet, ceramics, cubic boron nitride sintered body, diamond sintered body, and high-speed steel. Among these, the base material is preferably one of cemented carbide, cermet, ceramics, or cubic boron nitride sintered body, and more preferably cemented carbide. Using such a base material tends to result in coated cutting tools with excellent fracture resistance and wear resistance.

[0018] The coating layer of this embodiment is formed on the surface of the substrate and includes, in order from the substrate side toward the surface of the coating layer, a lower layer and an upper layer, and may also include an outer layer if necessary. The average thickness of the entire coating layer is not particularly limited, but is preferably between 6.0 μm and 30.0 μm. When the average thickness of the entire coating layer is 6.0 μm or more, it tends to have excellent abrasion resistance and resistance to plastic deformation, and when it is 30.0 μm or less, the adhesion of the coating layer improves, and it tends to have excellent chipping resistance and resistance to fracture. From a similar viewpoint, the average thickness of the entire coating layer is more preferably between 7.6 μm and 29.7 μm, and even more preferably between 11.3 μm and 19.4 μm.

[0019] [Lower layer] The lower layer of this embodiment includes one or more Ti compound layers, each consisting of a Ti compound of Ti and at least one element selected from the group consisting of C, N, O, and B. By providing the above lower layer between the substrate and the upper layer containing the α-type Al2O3 layer, the adhesion and wear resistance of the coated cutting tool are improved.

[0020] Examples of Ti compound layers include a TiC layer made of TiC (hereinafter also simply referred to as the "TiC layer"), a TiN layer made of TiN (hereinafter also simply referred to as the "TiN layer"), a TiCN layer made of TiCN (hereinafter also simply referred to as the "TiCN layer"), a TiCO layer made of TiCO (hereinafter also simply referred to as the "TiCO layer"), a TiCNO layer made of TiCNO (hereinafter also simply referred to as the "TiCNO layer"), a TiON layer made of TiON (hereinafter also simply referred to as the "TiON layer"), and a TiB2 layer made of TiB2 (hereinafter also simply referred to as the "TiB2 layer"). From the viewpoint of achieving the effects of the present invention more effectively and reliably, it is preferable that the lower Ti compound layer includes a TiN layer, a TiCN phase, a TiCO layer, and / or a TiCNO layer.

[0021] The lower layer may consist of one layer or multiple layers (for example, two or three layers). From the viewpoint of achieving the effects of the present invention more effectively and reliably, it is preferable that the lower layer be composed of multiple layers, more preferably two or more layers, even more preferably three or more layers, and still more preferably three layers. When the lower layer consists of three layers, a TiC layer or TiN layer may be provided as the first layer on the surface of the substrate, a TiCN layer may be provided as the second layer on the surface of the first layer, and a TiCNO layer or TiCO layer may be provided as the third layer on the surface of the second layer. Among these, it is preferable that the lower layer has a TiN layer as the first layer on the surface of the substrate, a TiCN layer as the second layer on the surface of the first layer, and a TiCNO layer or TiCO layer as the third layer on the surface of the second layer.

[0022] The average thickness of the lower layer in this embodiment is 3.0 μm or more and 15.0 μm or less. When the average thickness of the lower layer is 3.0 μm or more, it exhibits excellent abrasion resistance and resistance to plastic deformation, and when it is 15.0 μm or less, peeling of the coating layer is suppressed, and it exhibits excellent chipping resistance and fracture resistance. From a similar viewpoint, the average thickness of the lower layer is preferably 3.7 μm or more and 14.7 μm or less, and more preferably 4.2 μm or more and 13.7 μm or less.

[0023] When the lower layer is formed of the first to third layers as described above, the average thickness of the first layer formed on the surface of the substrate is preferably 0.1 μm or more and 1.2 μm or less, from the viewpoint of further improving chipping resistance and / or abrasion resistance. From the same viewpoint, the average thickness of the first layer is more preferably 0.1 μm or more and 0.6 μm or less, and even more preferably 0.1 μm or more and 0.3 μm or less.

[0024] When the lower layer is formed of the first to third layers as described above, the average thickness of the second layer formed on the surface of the first layer is preferably 3.0 μm or more and 15.0 μm or less, from the viewpoint of further improving chipping resistance and / or wear resistance. From the same viewpoint, the average thickness of the second layer is more preferably 3.5 μm or more and 13.5 μm or less, and even more preferably 5.8 μm or more and 13.0 μm or less.

[0025] When the lower layer is formed of the first to third layers as described above, the average thickness of the third layer formed on the surface of the second layer is preferably 0.1 μm or more and 3.0 μm or less from the viewpoint of further improving chipping resistance and / or wear resistance. From the same viewpoint, the average thickness of the third layer is more preferably 0.3 μm or more and 2.0 μm or less, and even more preferably 0.5 μm or more and 1.0 μm or less.

[0026] The Ti compound layer is a layer made of a Ti compound of Ti and at least one element selected from the group consisting of C, N, O, and B, but it may also contain trace amounts of elements other than those mentioned above, as long as the effects of the lower layer are achieved.

[0027] [Top layer] The upper layer of this embodiment includes an α-type Al2O3 layer (hereinafter also simply referred to as the "α-type Al2O3 layer") made of α-type Al2O3. Furthermore, the upper layer of this embodiment includes a lower upper layer that occupies a range from the interface with the lower layer (however, if there are irregularities at the interface, the position closest to the surface of the coating layer) toward the interface on the surface side of the coating layer to 1 μm, and an upper upper layer that occupies a range closer to the surface of the coating layer than the lower upper layer.

[0028] The average thickness of the upper layer in this embodiment is 3.0 μm or more and 15.0 μm or less. When the average thickness of the upper layer is 3.0 μm or more, crater wear is suppressed, resulting in excellent wear resistance and resistance to plastic deformation. When it is 15.0 μm or less, the adhesion between the lower layer and the upper layer is improved, resulting in excellent chipping resistance and resistance to fracture. From a similar viewpoint, the average thickness of the upper layer is preferably 3.2 μm or more and 14.8 μm or less, and more preferably 4.0 μm or more and 12.0 μm or less.

[0029] In the upper layer, if the average particle size in the direction parallel to the surface of the substrate at a position 0.5 μm from the interface on the lower layer side toward the surface of the coating layer is defined as the first average particle size, and in the upper layer, if the average particle size in the direction parallel to the surface of the substrate at a position 1.0 μm from the interface on the opposite side of the substrate toward the interface on the substrate side is defined as the second average particle size, then it is preferable that the ratio of the second average particle size to the first average particle size is 1.0 or more and 2.0 or less. When the ratio of average particle sizes is 1.0 or higher, the formation of the upper layer tends to be easier. When the ratio of average particle sizes is 2.0 or lower, cracks caused by the difference in particle size between the lower upper layer and the upper upper layer tend to be suppressed from occurring inside the upper layer. As a result, the adhesion between the lower upper layer and the upper upper layer is improved, resulting in excellent chipping resistance and fracture resistance. From a similar viewpoint, the ratio of the second average particle size to the first average particle size is more preferably 1.2 or higher and 1.8 or lower, and even more preferably 1.3 or higher and 1.7 or lower.

[0030] [Lower upper layer] The lower upper layer of this embodiment includes an α-type Al2O3 layer made of α-type Al2O3, occupying a range from the interface on the lower layer side (however, if there are irregularities at the interface, the position closest to the surface of the coating layer) toward the interface on the surface side of the coating layer to 1 μm, and satisfying the conditions expressed by formula (1). In formula (1), RSA1 is the ratio (unit: area%) of the cross-sectional area of ​​particles whose orientation difference, which is the angle between the normal to the surface of the substrate and the normal to the (110) plane of the particles in the α-type Al2O3 layer, is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section of the lower upper layer in a direction perpendicular to the surface of the substrate is taken as 100 area%. 40 ≤ RSA1 ≤ 80 (1)

[0031] In the lower upper layer, if the RSA1 content is 40% or more, adhesion to the lower layer is improved, resulting in improved chipping resistance and fracture resistance. Furthermore, if the RSA1 content is 80% or less, the formation of the lower upper layer becomes easier. From a similar viewpoint, it is preferable that the RSA1 content is 42% to 79% and more preferably 50% to 72%.

[0032] It is preferable that the lower upper layer of this embodiment satisfies the conditions represented by the following formula (3). When RSB1 is greater than 0 area%, the formation of the lower upper layer tends to be easier, and when RSB1 is 20 area% or less, the adhesion between the lower layer and the upper layer improves, and chipping resistance and fracture resistance tend to improve. From a similar viewpoint, it is more preferable that RSB1 is greater than 0 area% and 16 area% or less, and even more preferable that it is greater than 0 area% and 15 area% or less. 0 <RSB1≦20 (3) In formula (3), RSB1 is the ratio (in area %) of the cross-sectional area of ​​particles in the lower upper layer in a direction perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (012) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100%.

[0033] In this embodiment, the first average particle size is the average particle size in the upper layer, in a direction parallel to the surface of the substrate, at a position 0.5 μm from the interface on the lower layer side toward the surface of the coating layer. The first average particle size is preferably 0.3 μm or more and 0.5 μm or less. When the first average particle size is 0.3 μm or more, it tends to be easier to control the orientation in the lower upper layer. Also, when the first average particle size is 0.5 μm or less, the peeling area when the upper layer peels off can be reduced, and the region that becomes the starting point of fracture becomes smaller, so the fracture resistance tends to improve. From a similar viewpoint, it is more preferable that the first average particle size is 0.3 μm or more and 0.4 μm or less.

[0034] The lower upper layer contains an α-type Al2O3 layer made of α-type Al2O3, but it may also contain components other than α-type Al2O3 as long as it achieves the effects of the present invention.

[0035] [Upper upper layer] The upper upper layer occupies a portion of the upper layer that is closer to the surface of the coating layer than the lower upper layer, and satisfies the conditions expressed by the following formula (2). In formula (2), RSB2 is the ratio (unit: area%) of the cross-sectional area of ​​particles in the upper upper layer in a direction perpendicular to the surface of the substrate, where the orientation difference between the normal to the surface of the substrate and the normal to the (012) plane of the particles in the α-type Al2O3 layer is 0 degrees or more and 20 degrees or less, when the total area of ​​the entire cross-section is 100 area%. 50 ≤ RSB2 ≤ 90 (2)

[0036] In the upper upper layer, if the RSB2 is 50 area % or more, the mechanical strength is improved, and thus the fracture resistance is improved. Also, if the RSB2 is 90 area % or less, the formation of the upper upper layer becomes easier. From a similar viewpoint, it is preferable that the RSB2 is 52 area % or more and 88 area % or less, and more preferable that it is 58 area % or more and 82 area % or less.

[0037] It is preferable that the upper layer of this embodiment satisfies the conditions represented by the following formula (4). When the RSA2 content in the upper layer is 10 area% or less, the mechanical strength improves, which tends to improve fracture resistance. From a similar viewpoint, it is more preferable that the RSA2 content is 0 area% to 8 area%, and even more preferable that it is 0 area% to 6 area%. 0 ≤ RSA2 ≤ 10 (4) In formula (4), RSA2 is the percentage of the cross-sectional area (unit: area%) of particles whose orientation difference, which is the angle between the normal to the surface of the substrate and the normal to the (110) plane of the particles in the α-type Al2O3 layer, is between 0 degrees and 20 degrees, when the total area of ​​the entire cross-section in the upper layer perpendicular to the surface of the substrate is taken as 100 area%.

[0038] In this embodiment, the second average particle size is the average particle size of particles in the upper layer in a direction parallel to the surface of the substrate, at a position 1.0 μm from the interface opposite to the substrate toward the interface on the substrate side. The second average particle size is preferably 0.3 μm or more and 1.0 μm or less. When the second average particle size is 0.3 μm or more, the generation and propagation of cracks originating from the grain boundaries of the particles in the α-type Al2O3 layer are suppressed, so the amount of workpiece components that enter the interface between the upper layer and the lower layer through cracks is reduced. As a result, the adhesion between the upper layer and the lower layer is improved, and chipping resistance tends to improve. Furthermore, when the second average particle size is 1.0 μm or less, the peeling area when the upper layer peels off can be reduced, and the region that becomes the starting point of fracture is reduced, so chipping resistance tends to improve. From a similar viewpoint, the second average particle size is more preferably 0.4 μm or more and 0.9 μm or less, and even more preferably 0.5 μm or more and 0.8 μm or less.

[0039] The upper layer contains an α-type Al2O3 layer, but it may also contain components other than α-type Al2O3, as long as it achieves the effects of the present invention.

[0040] [External layer] The coating layer of this embodiment may include an outer layer on the interface opposite to the substrate of the upper layer (i.e., the surface of the upper layer). The outer layer is preferably a layer of a compound consisting of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si, and Y, and at least one element selected from the group consisting of C, N, O, and B (preferably C and / or N), as this tends to have excellent wear resistance. From a similar viewpoint, the outer layer is more preferably a layer of a compound consisting of at least one element selected from the group consisting of Ti, Nb, Cr, Al, and Si, and at least one element selected from the group consisting of C, N, O, and B (preferably C and / or N), even more preferably a layer of a compound consisting of at least one element selected from the group consisting of Ti, Cr, Al, and Si, and N, and particularly preferably a TiN layer made of TiN.

[0041] The average thickness of the outer layer is not particularly limited and may be, for example, 0.1 μm or more and 5.0 μm or less. From the viewpoint of achieving the effects of the present invention more effectively and reliably, the average thickness of the outer layer is preferably 0.15 μm or more and 3.0 μm or less, and more preferably 0.2 μm or more and 2.0 μm or less.

[0042] [Measurement methods for RSA and RSB] In this embodiment, as a method for measuring RSA and RSB, for example, the cross-section to be measured can be observed with an electrolytic emission scanning electron microscope (FE-SEM), and the cross-sectional area of ​​particles with a specific orientation difference can be measured using an electron backscattering imaging device (EBSD) attached to the FE-SEM. RSA1 and RSA2, and RSB1 and RSB2, may also be calculated by measuring the orientation difference and determining the cross-sectional area of ​​the particles in the same manner, except that the measurement range differs between the crystal plane and the coating layer. More specifically, they can be determined, for example, by the method described in the examples below.

[0043] [Method for forming a coating layer] The method for forming the coating layer in the coated cutting tool of this embodiment is not particularly limited, but examples include the following methods. However, the method for forming each layer is not limited thereto.

[0044] For example, the lower Ti compound layer is formed by the following method. A Ti compound layer consisting of a Ti nitride layer can be formed by chemical vapor deposition using a raw material composition of TiCl4: 5.0-10.0 mol%, N2: 20-60 mol%, and H2: the remainder, at a temperature of 850-950°C and a pressure of 300-400 hPa.

[0045] A Ti compound layer consisting of a Ti carbide layer can be formed by chemical vapor deposition using a raw material composition of TiCl4: 1.5-3.5 mol%, CH4: 3.5-5.5 mol%, and H2: the remainder, at a temperature of 950-1050°C and a pressure of 70-80 hPa.

[0046] A Ti compound layer consisting of a Ti carbonitride layer can be formed by chemical vapor deposition using a raw material composition of TiCl4: 5.0-7.0 mol%, CH3CN: 0.5-1.5 mol%, and H2: the remainder, at a temperature of 800-900°C and a pressure of 60-80 hPa.

[0047] A Ti compound layer consisting of a Ti carbonitroxide layer can be formed by chemical vapor deposition using a raw material composition of TiCl4: 3.0-4.0 mol%, CO: 0.5-1.0 mol%, N2: 30-40 mol%, and H2: the remainder, at a temperature of 950-1050°C and a pressure of 50-150 hPa.

[0048] A Ti compound layer consisting of a Ti carbon oxide layer can be formed by chemical vapor deposition using a raw material composition of TiCl4: 1.0-2.0 mol%, CO: 2.0-3.0 mol%, and H2: the remainder, at a temperature of 950-1050°C and a pressure of 50-150 hPa.

[0049] The lower upper layer of the α-type Al2O3 layer is formed, for example, by the following method. First, a lower layer consisting of one or more Ti compound layers is formed on the surface of the substrate. Next, the surface of the layer furthest from the substrate (the non-substrate layer) is oxidized. After that, an α-type Al2O3 layer is formed on the surface of the layer furthest from the substrate.

[0050] More specifically, oxidation of the surface of the layer furthest from the substrate is carried out under the following conditions: the raw material composition is CO: 0-2.0 mol%, CO2: 0.3-1.0 mol%, H2: the remainder, the temperature is 950-1050°C, and the pressure is 50-60 hPa (oxidation step 1). The oxidation treatment time is preferably 1-10 minutes.

[0051] Subsequently, the formation of the α-type Al2O3 layer in the lower upper layer is carried out by chemical vapor deposition under the following conditions: the raw material composition is AlCl3: 1.0-2.5 mol%, CO2: 1.0-2.5 mol%, HCl: 2.0-3.0 mol%, H2S: 0.05-0.10 mol%, H2: remainder, the temperature is 950-1000°C, and the pressure is 60-80 hPa (film formation step 1). In this case, the processing time for film formation step 1 is preferably 15-120 minutes, and the CO2 / H2S range may be, for example, 10-50 or 10-48.

[0052] To keep RSA1 (area %) within a predetermined range, the proportions of AlCl3, CO2, and H2S in the raw material composition can be controlled in the film formation process 1. Specifically, by increasing the proportion of CO2 or decreasing the proportion of H2S in the raw material composition of the film formation process 1, the proportion (area %) of particles with an orientation difference A within a predetermined range can be increased, and RSA1 tends to increase.

[0053] To keep RSB1 (area %) within a predetermined range, the proportion of AlCl3 in the raw material composition during the film formation process 1 can be controlled. Specifically, by reducing the proportion of AlCl3 in the raw material composition during the film formation process 1, the proportion (area %) of particles with orientation difference B within a predetermined range can be reduced, and RSB1 tends to decrease.

[0054] To keep the first average particle size within a predetermined range, the temperature in the film deposition process 1 can be controlled, or the proportion of each component in the raw material composition can be controlled. Specifically, increasing the temperature in the film deposition process 1, controlling the process to increase RSA1, or controlling the process to decrease RSB1 tends to increase the first average particle size, and increasing the temperature in the film deposition process 1 increases the first average particle size more effectively.

[0055] After the lower upper layer is formed, an α-type Al2O3 layer of the upper upper layer is formed on its surface. For example, it can be formed by the following method.

[0056] The formation of the α-type Al2O3 layer in the upper layer is carried out by chemical vapor deposition (film formation step 2) under the following conditions: the raw material composition is AlCl3: 2.0-5.0 mol%, CO2: 2.0-4.0 mol%, HCl: 2.0-3.0 mol%, H2S: 0.1-0.3 mol%, and H2: the remainder, at a temperature of 950-1000°C and a pressure of 60-80 hPa. In this case, the CO2 / H2S range may be, for example, 6.7-40 or 10-26.7.

[0057] To keep RSA2 (area %) within a predetermined range, the proportion of each component in the raw material composition in film formation step 1 or in film formation step 2 should be controlled. Specifically, controlling the ratio so that RSA1 is small or controlling the ratio so that RSB2 is large tends to reduce RSA2.

[0058] To keep RSB2 (area %) within a predetermined range, the proportions of AlCl3, CO2, and H2S in the raw material composition during the film formation process 2 should be controlled. Specifically, by increasing the proportion of CO2, decreasing the proportion of H2S, or increasing the proportion of AlCl3 in the raw material composition during the film formation process 2, the proportion of particles (area %) with an orientation difference B within a predetermined range can be increased, and RSB2 tends to increase.

[0059] To keep the second average particle size within a predetermined range, the temperature in the film formation process 2 can be controlled, or the proportion of each component in the raw material composition can be controlled. Specifically, increasing the temperature in the film formation process 2, controlling the process to increase RSA2, or controlling the process to decrease RSB2 tends to increase the second average particle size, and increasing the temperature in the film formation process 2 tends to increase the second average particle size more effectively.

[0060] An outer layer consisting of a TiN layer and / or a TiCN layer may be formed on the surface of the upper layer, if necessary. The outer layer can be formed, for example, by the following method.

[0061] The TiN layer, which serves as the outer layer, can be formed by chemical vapor deposition using a raw material composition of TiCl4: 5.0-10.0 mol%, N2: 20-60 mol%, and H2: the remainder, at a temperature of 950-1050°C and a pressure of 300-400 hPa.

[0062] The TiCN layer, which serves as the outer layer, can be formed by chemical vapor deposition using a raw material composition of TiCl4: 4.0-8.0 mol%, CH3CN: 0.5-2.0 mol%, N2: 0-10.0 mol%, and H2: the remainder, at a temperature of 950-1050°C and a pressure of 60-80 hPa.

[0063] The thickness of each layer in the coating of the coated cutting tool of this embodiment can be measured by observing the cross-sectional structure of the coated cutting tool using an optical microscope, scanning electron microscope (SEM), or FE-SEM. The average thickness of each layer in the coated cutting tool of this embodiment can be determined by measuring the thickness of each layer at three or more locations near a point 50 μm from the cutting edge towards the center of the rake face of the coated cutting tool, and calculating the arithmetic mean. The composition of each layer can be measured from the cross-sectional structure of the coated cutting tool of this embodiment using an energy-dispersive X-ray spectrometer (EDS) or a wavelength-dispersive X-ray spectrometer (WDS).

[0064] The coated cutting tools of this embodiment are thought to have the effect of extending tool life compared to conventional tools, at least due to their superior fracture resistance and wear resistance (however, the factors that can extend tool life are not limited to those mentioned above). Specifically, examples of coated cutting tools of this embodiment include replaceable cutting inserts for milling or turning, drills, and end mills. [Examples]

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0066] [Inventions 1-26 and Comparative Products 1-11] As the base material, a cemented carbide alloy with a composition of 93.7%WC-6.0%Co-0.3%Cr3C2 (by mass%) was prepared, machined into an insert shape from CNMG120408. After round honing of the cutting edge ridge of this base material using a SiC brush, the surface of the base material was cleaned.

[0067] After cleaning the surface of the substrate, a coating layer was formed by chemical vapor deposition. First, the substrate was placed in the thermal chemical vapor deposition apparatus, and under the raw material composition, temperature, and pressure conditions shown in Table 1, a first layer with the composition shown in Tables 6 and 7 was formed on the surface of the substrate to the average thickness shown in Tables 6 and 7. Next, under the raw material composition, temperature, and pressure conditions shown in Table 1, a second layer, as shown in Tables 6 and 7, was formed on the surface of the first layer to the average thickness shown in Tables 6 and 7. Then, under the raw material composition, temperature, and pressure conditions shown in Table 1, a third layer, as shown in Tables 6 and 7, was formed on the surface of the second layer to the average thickness shown in Tables 6 and 7. This formed a lower layer consisting of three layers. Subsequently, the surface of the third layer was subjected to an oxidation treatment for 5 minutes under the conditions of CO2:0.5 mol%, H2:99.5 mol%, temperature 1000°C, and pressure 55 hPa.

[0068] Next, the lower upper layer of the α-type Al2O3 layer was formed on the surface of the oxidized third layer under the raw material composition, temperature, and pressure conditions shown in Tables 2 and 3, with the deposition time adjusted to achieve an average thickness of 1 μm. Then, the upper upper layer of the α-type Al2O3 layer was formed on the surface of the lower upper layer under the raw material composition, temperature, and pressure conditions shown in Tables 4 and 5, with the deposition time adjusted to achieve an average thickness of the entire upper layer as shown in Tables 6 and 7.

[0069] Furthermore, for all inventions and comparative products except for invention 18, an outer layer having the composition described in Tables 6 and 7 was formed on the surface of the upper layer under the raw material composition, temperature, and pressure conditions shown in Table 1, so as to have the average thickness described in Tables 6 and 7. Thus, coated cutting tools, inventions 1-26 and comparative inventions 1-11, were obtained.

[0070] The thickness of each layer in the sample was determined as follows: Using FE-SEM, the thickness was measured at three points in the cross-section near a position 50 μm from the cutting edge of the coated cutting tool toward the center of the rake face, and the arithmetic mean of these measurements was calculated as the average thickness. The composition of each layer in the obtained sample was measured using EDS in the cross-section near a position 50 μm from the cutting edge of the coated cutting tool toward the center of the rake face. The measurement results are shown in Tables 6 and 7.

[0071] [Table 1]

[0072] [Table 2]

[0073] [Table 3]

[0074] [Table 4]

[0075] [Table 5]

[0076] [Table 6]

[0077] [Table 7]

[0078] [Measurement and calculation of RSA1, RSA2, RSB1, and RSB2] For RSA1, RSA2, RSB1, and RSB2, the following measurement cross-sections were observed using an electrolytic emission scanning electron microscope (FE-SEM) under the conditions described below. The cross-sectional areas of particles with an orientation difference between 0 and 20 degrees, and the sum of the cross-sectional areas of particles with an orientation difference between 0 and 90 degrees, were measured using the electron backscatter analysis imaging device (EBSD) attached to the FE-SEM, according to the "(Method for measuring the cross-sectional area of ​​particles with a specific orientation difference)" described later. Note that the sum of the cross-sectional areas of particles with an orientation difference between 0 and 90 degrees is equal to the sum of the total area of ​​the cross-sections, and represents 100 area %. RSA1, RSA2, RSB1, and RSB2 were defined as the percentage of the cross-sectional area of ​​particles with an orientation difference between 0 and 20 degrees relative to the total cross-sectional area of ​​particles with an orientation difference between 0 and 90 degrees relative to 100% of the total cross-sectional area of ​​particles with an orientation difference between 0 and 90 degrees relative to RSA1, RSB2, RSB1, and RSB2, respectively. The measurement results are shown in Tables 8 and 9. (conditions) • Method for machining the measurement cross-section RSA1, RSA2, RSB1, and RSB2: Coated cutting tools were polished using diamond paste to obtain a cross-sectional microstructure perpendicular to the surface of the substrate. Then, finish polishing was performed using colloidal silica to obtain a mirror-polished surface of the cross-sectional microstructure. • Measurement cross-section RSA1 and RSB1: The cross-section of the upper layer perpendicular to the surface of the substrate, from the interface on the lower layer side (however, if there are irregularities at the interface, the position closest to the surface of the coating layer) toward the interface on the surface side of the coating layer, up to 1 μm. RSA2 and RSB2: The portion of the upper layer cross-section perpendicular to the surface of the substrate, on the surface side of the coating layer compared to the lower upper layer. ·Direction difference RSA1 and RSA2: Orientation difference A (angle between the normal to the surface of the substrate and the normal to the (110) plane of the particles in the α-type Al2O3 layer (unit: degrees)) RSB1 and RSB2: Orientation difference B (angle between the normal to the surface of the substrate and the normal to the (012) plane of the particles in the α-type Al2O3 layer (unit: degrees))

[0079] (Method for measuring the cross-sectional area of ​​particles with a specific orientation difference) The sample was set in the FE-SEM. The sample was irradiated with an electron beam at an incidence angle of 70 degrees, with an acceleration voltage of 15 kV and an irradiation current of 1.0 nA. The orientation difference and cross-sectional area of ​​each particle were measured in a measurement range of 30 μm × 50 μm with an EBSD setting of a step size of 0.05 μm. The cross-sectional area of ​​the particles in the upper layer within the measurement range was defined as the sum of the pixels corresponding to that cross-sectional area. That is, the sum of the cross-sectional areas of particles in each layer within the range of 0 degrees to 20 degrees and within the range of 0 degrees to 90 degrees, based on orientation difference A or orientation difference B, was calculated by totaling the pixels occupied by the particle cross-sections corresponding to each range and converting them to area.

[0080] [Table 8]

[0081] [Table 9]

[0082] [First average particle size and second average particle size] For the obtained inventions 1-26 and comparative products 1-11, the average particle size of the α-type Al2O3 particles constituting the lower upper layer and upper upper layer was measured using an EBSD attached to the FE-SEM. Specifically, a coated cutting tool was polished using diamond paste to obtain a cross-sectional structure parallel to the surface of the substrate. Then, finish polishing was performed using colloidal silica to obtain a mirror-polished surface of the cross-sectional structure. The sample with the cross-sectional structure was set in the FE-SEM, and the sample was irradiated with an electron beam at an incident angle of 70 degrees with an acceleration voltage of 15 kV and an irradiation current of 1.0 nA. Measurements were performed in a measurement range of 30 μm × 50 μm with an EBSD setting of a step size of 0.05 μm. Using EBSD, the average particle size 1 (first average particle size) of the particles in the cross-sectional microstructure of the upper layer of the coated cutting tool was measured in a direction parallel to the surface of the substrate at a position 0.5 μm from the interface between the lower and upper layers toward the surface of the coating layer, and the average particle size 2 (second average particle size) of the particles in a direction parallel to the surface of the substrate at a position 1.0 μm from the interface opposite to the substrate toward the interface on the substrate side in the upper layer. More specifically, first, if there was an orientation difference of 5 degrees or more between adjacent measurement points, that point was defined as a grain boundary. The region enclosed by the grain boundary was defined as a single crystal grain. Then, the first and second average grain sizes were determined. At each of the above locations, a straight line was drawn parallel to the surface of the substrate. Next, the number of crystal grains contained within the range of each straight line was determined. The values ​​obtained by dividing the length of the straight line by the number of crystal grains were defined as the first and second average grain sizes. In this case, the length of the straight line was set to 20 μm. The obtained results for the first and second average grain sizes are shown in Tables 10 and 11.

[0083] [Table 10]

[0084] [Table 11]

[0085] The obtained samples were used to perform the following cutting tests and evaluations.

[0086] [Cutting Test 1] • Insert: CNMG120408 (ISO standard) • Base material composition: 93.7%WC-6.0%Co-0.3%Cr3C2 (by mass %) • Workpiece material: FCD600, • Workpiece shape: Cylindrical shape with a diameter of 120 mm and a length of 400 mm (four grooves evenly spaced on the outer circumference of the cylinder) ·Cutting speed: 150m / min, • Cutting depth: 2.0 mm, Feed rate: 0.35mm / rev, • Coolant: Use • Evaluation criteria: Tool life was defined as the point at which the sample fractured, and the number of impacts at which fracture occurred was measured. The better the fracture resistance, the longer the tool life (more impacts) in this cutting test.

[0087] [Cutting Test 2] • Insert: CNMG120408 (ISO standard) • Base material composition: 93.7%WC-6.0%Co-0.3%Cr3C2 (by mass %) • Workpiece material: FC200, • Workpiece shape: Disc shape with a diameter of 180 mm and a thickness of 23 mm (with a 70 mm diameter hole in the center of the disc) ·Cutting speed: 700m / min, • Cutting depth: 2.0 mm, Feed rate: 0.30mm / rev, • Coolant: Use • Evaluation item: Tool life was defined as the machining time (minutes) until the flank wear width reached 0.3 mm. The better the wear resistance and resistance to plastic deformation, the longer the tool life (machining time) in this cutting test.

[0088] The results of the evaluations obtained are shown in Tables 12 and 13. For cutting test 1, the number of impacts was evaluated as "A" for 15,000 or more, "B" for 10,000 or more but less than 15,000, and "C" for less than 10,000. For cutting test 2, the processing time was evaluated as "A" for 25 minutes or more, "B" for 20 minutes or more but less than 25 minutes, and "C" for less than 20 minutes.

[0089] [Table 12]

[0090] [Table 13]

[0091] As shown in Tables 12 and 13, the invention received a rating of B or higher in both Cutting Test 1 and Cutting Test 2. From these results, it was found that an invention comprising a coated cutting tool, a base material, and a coating layer formed on the surface of the base material, wherein the coating layer includes a lower layer and an upper layer in that order from the base material side toward the surface of the coating layer, the lower layer includes one or more Ti compound layers made of Ti and at least one element selected from the group consisting of C, N, O, and B, the upper layer includes an α-type Al2O3 layer made of α-type Al2O3, the average thickness of the lower layer is 3.0 μm or more and 15.0 μm or less, the average thickness of the upper layer is 3.0 μm or more and 15.0 μm or less, and in the upper layer, the range from the interface on the lower layer side toward the interface on the surface side of the coating layer is defined as the lower upper layer, and the range on the surface side of the coating layer is defined as the upper upper layer, and the lower upper layer satisfies the condition represented by formula (1), and the upper upper layer satisfies the condition represented by formula (2), has excellent fracture resistance and wear resistance and a long tool life. [Industrial applicability]

[0092] The coated cutting tool of the present invention has excellent fracture resistance and wear resistance, which extends tool life compared to conventional tools, and therefore has high potential for industrial application. [Explanation of Symbols]

[0093] 1...Base material, 2...Lower layer, 3...Upper layer, 3a...Lower upper layer, 3b...Upper upper layer, 4...Coating layer, 5...Coated cutting tool.

Claims

1. A coated cutting tool comprising a base material and a coating layer formed on the surface of the base material, The coating layer includes a lower layer and an upper layer in this order, from the substrate side toward the surface of the coating layer. The lower layer comprises one or more Ti compound layers, each consisting of a Ti compound of Ti and at least one element selected from the group consisting of C, N, O, and B, and the upper layer comprises α-type Al 2 O 3 α-type Al consisting of 2 O 3 Including layers, The average thickness of the lower layer is 3.0 μm or more and 15.0 μm or less. The average thickness of the upper layer is 3.0 μm or more and 15.0 μm or less. In the upper layer, if the area from the interface on the lower layer side (however, if there are irregularities on the interface, the position closest to the surface of the coating layer) to the interface on the surface side of the coating layer is defined as the lower upper layer, and the area closer to the surface of the coating layer than the lower upper layer is defined as the upper upper layer, In the aforementioned lower upper layer, the following condition expressed by formula (1) is satisfied, 40 ≤ RSA1 ≤ 80 (1) (In formula (1), RSA1 is the normal to the surface of the substrate and α-type Al when the total area of ​​the entire cross-section of the lower upper layer in a direction perpendicular to the surface of the substrate is 100 area %.) 2 O 3 This is the percentage (in area %) of the cross-sectional area of ​​particles in a layer whose orientation difference—the angle between the normal to the (110) plane of the particle and the layer's particles—is between 0 degrees and 20 degrees. In the upper layer mentioned above, the following condition expressed by formula (2) is satisfied, 50 ≤ RSB2 ≤ 90 (2) (In formula (2), RSB2 is the normal to the surface of the substrate and α-type Al when the total area of ​​the entire cross-section of the upper upper layer in a direction perpendicular to the surface of the substrate is 100 area %. 2 O 3 This is the percentage (in area %) of the cross-sectional area of ​​particles in the layer whose orientation difference—the angle between the normal to the (012) plane of the particle—is between 0 degrees and 20 degrees. In the upper layer, the average particle size of the particles in a direction parallel to the surface of the substrate at a position of 0.5 μm from the interface on the lower layer side toward the surface of the coating layer is defined as the first average particle size. In the upper layer, if the average particle size of the particles in a direction parallel to the surface of the substrate at a position 1.0 μm from the interface opposite to the substrate toward the interface on the substrate side is defined as the second average particle size, The ratio of the second average particle size to the first average particle size is 1.0 or more and 2.0 or less. Coated cutting tools.

2. In the aforementioned lower upper layer, the following conditions are met, as expressed by formula (3): 0 < RSB1 ≤ 20 (3) (In Formula (3), RSB1 is, in the cross-section of the lower upper layer in the direction perpendicular to the surface of the base material, when the total area of the entire cross-section is 100 area%, the normal line of the surface of the base material and α-type Al 2 O 3 It is the ratio (unit: area%) of the cross-sectional area of particles whose azimuthal difference formed by the normal line of the (012) plane of the particles of the layer is 0 degrees or more and 20 degrees or less.) The coated cutting tool according to claim 1.

3. In the upper upper layer, the following conditions are met, as shown in equation (4): 0 ≤ RSA² ≤ 10 (4) (In formula (4), RSA2 is the normal to the surface of the substrate and α-type Al when the total area of ​​the entire cross-section of the upper layer in a direction perpendicular to the surface of the substrate is 100 area %. 2 O 3 This is the percentage (in area %) of the cross-sectional area of ​​particles in a layer whose orientation difference—the angle between the normal to the (110) plane of the particle and the layer's particles—is between 0 degrees and 20 degrees. A coated cutting tool according to claim 1 or 2.

4. The first average particle size is 0.3 μm or more and 0.5 μm or less. The coated cutting tool according to claim 1.

5. The second average particle size is 0.3 μm or more and 1.0 μm or less. The coated cutting tool according to claim 1.

6. The average thickness of the coating layer is 6.0 μm or more and 30.0 μm or less. A coated cutting tool according to claim 1 or 2.

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