JP7754004B2 - cutting tools - Google Patents

Description

This disclosure relates to cutting tools.

Conventionally, in order to improve the performance of cutting tools, development has been underway for coatings that coat the surface of substrates made of cemented carbide, cubic boron nitride sintered body, etc. For example, Patent Document 1 discloses a cutting tool including, on the surface of the tool substrate, a composite nitride coating represented by the composition formula: (Ti1 _{-x- yAlxMy} ) _Nz (in this composition formula, M is at least one of Group 6 elements of _the periodic table, Y, Si, La, and Ce).

International Publication No. 2020/166466

In Patent Document 1, for example, a TiAlCeN film using cerium (Ce) as M has high hardness but tends to have reduced toughness. When this TiAlCeN film is used under machining conditions that place a heavy load on the cutting edge (for example, intermittent machining of steel), chipping of the cutting edge tends to occur, resulting in a reduced tool life.

Therefore, the present disclosure aims to provide a cutting tool with a long tool life.

The cutting tool of the present disclosure comprises:
1. A cutting tool comprising a substrate and a coating disposed on the substrate,
The cutting tool comprises:
Rake face,
a flank surface connected to the rake surface; and
a cutting edge formed by a boundary portion between the rake face and the flank face,
the coating comprises a TiAlCeN layer;
The TiAlCeN layer is
a first TiAlCeN layer located on the rake face or the flank face;
a second TiAlCeN layer located on the cutting edge;
The composition of the first TiAlCeN layer is Ti _x1 Al _y1 Ce _z1 N,
The composition of the second TiAlCeN layer is Ti _x2 Al _y2 Ce _z2 N,
where:
x1+y1+z1=1,
x2+y2+z2=1,
0.300<y1≦0.700,
0.300<y2≦0.700,
0.010<z1≦0.100,
0<z2≦0.090, and
The cutting tool has z1-z2≧0.010.

This disclosure makes it possible to provide cutting tools with long tool life.

FIG. 1 is a perspective view illustrating an example of a cutting tool according to an embodiment of the present disclosure. 2 is a cross-sectional view of the cutting tool of FIG. 1, taken along the line II-II in FIG. FIG. 3 is a cross-sectional perspective view showing the shaded portion of FIG. 1, showing region III. FIG. 4 is a partial view of the cross section shown in FIG. 2 in which the cutting edge has been honed. FIG. 5 is a cross-sectional perspective view showing the cutting edge of the cutting tool shown in FIG. 3 after honing. FIG. 6 is a partial view of the cross section shown in FIG. 2 in which a negative land is machined on the cutting edge. FIG. 7 is a cross-sectional perspective view of the cutting edge shown in FIG. 3 in which a negative land is formed on the cutting edge. FIG. 8 is a partial view of the cross section shown in FIG. 2 in which the cutting edge is subjected to honing and negative land machining. FIG. 9 is a cross-sectional perspective view of the cutting edge shown in FIG. 3, in which honing and negative land processing are performed on the cutting edge. FIG. 10 is a schematic cross-sectional view illustrating an example of a coating of a cutting tool according to an embodiment of the present disclosure. FIG. 11 is a diagram for explaining the cutting position of the cutting tool. FIG. 12 is a diagram for explaining the cutting position of the cutting tool. FIG. 13 is a diagram for explaining a method for setting the measurement field of view in measuring the composition of the TiAlCeN layer. FIG. 14 is a schematic cross-sectional view illustrating an example of a coating of a cutting tool according to an embodiment of the present disclosure. FIG. 15 is a diagram showing an example of the positional relationship between a target material, a substrate, and a shielding material in a chamber of a film forming apparatus. FIG. 16 is a diagram showing an example of the positional relationship between a target material, a substrate, and a shielding material in a chamber of a film forming apparatus.

Description of the embodiments of the present disclosure
First, embodiments of the present disclosure will be listed and described.
(1) The cutting tool of the present disclosure is
1. A cutting tool comprising a substrate and a coating disposed on the substrate,
The cutting tool comprises:
Rake face,
a flank surface connected to the rake surface; and
a cutting edge formed by a boundary portion between the rake face and the flank face,
the coating comprises a TiAlCeN layer;
The TiAlCeN layer is
a first TiAlCeN layer located on the rake face or the flank face;
a second TiAlCeN layer located on the cutting edge;
The composition of the first TiAlCeN layer is Ti _x1 Al _y1 Ce _z1 N,
The composition of the second TiAlCeN layer is Ti _x2 Al _y2 Ce _z2 N,
where:
x1+y1+z1=1,
x2+y2+z2=1,
0.300<y1≦0.700,
0.300<y2≦0.700,
0.010<z1≦0.100,
0<z2≦0.090, and
The cutting tool has z1-z2≧0.010.

This disclosure makes it possible to provide cutting tools with long tool life.

(2) In (1) above, the thickness of the TiAlCeN layer is preferably 0.5 μm or more and 15 μm or less. This further improves tool life.

(3) In the above (1) or (2), the coating further includes a first layer,
The first layer is
at least one element selected from the first group consisting of Group 4 elements, Group 5 elements, Group 6 elements, aluminum, and silicon of the periodic table; or
It is preferable that the first compound comprises at least one element selected from the first group and at least one element selected from the second group consisting of carbon, nitrogen, oxygen and boron.

This will further improve tool life.

(4) In (3) above, the first group preferably consists of titanium, chromium, aluminum, and silicon. This further improves tool life.

(5) In any of (1) to (4) above, the thickness of the coating is preferably 0.5 μm or more and 15 μm or less. This further improves tool life.

(6) In the above (3) or (4), it is preferable that the coating include a multilayer structure in which the TiAlCeN layers and the first layers are alternately stacked. This further improves tool life.

[Details of the embodiment of the present disclosure]
Specific examples of cutting tools according to the present disclosure will be described below with reference to the drawings. In the drawings, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

In this specification, the notation "A-B" means the upper and lower limits of a range (i.e., greater than or equal to A and less than or equal to B). If no unit is specified for A and only a unit is specified for B, the units for A and B are the same.

When compounds and the like are represented by chemical formulas in this specification, unless the atomic ratio is specifically limited, this includes any conventionally known atomic ratio and is not necessarily limited to the stoichiometric range. For example, when "TiCN" is written, the ratio of the numbers of atoms that make up TiCN includes any conventionally known atomic ratio.

In this disclosure, when one or more numerical values are recited as the lower limit and the upper limit of a numerical range, combinations of any one numerical value recited as the lower limit and any one numerical value recited as the upper limit are also considered to be disclosed. For example, if a1 or more, b1 or more, and c1 or more are recited as the lower limit and a2 or less, b2 or less, and c2 or less are recited as the upper limit, then a1 or more and a2 or less, a1 or more and b2 or less, a1 or more and c2 or less, b1 or more and a2 or less, b1 or more and b2 or less, b1 or more and c2 or less, c1 or more and a2 or less, c1 or more and b2 or less, and c1 or more and c2 or less are considered to be disclosed.

First, in order to obtain a cutting tool with a long tool life, the inventors investigated the damage patterns of conventional tools under machining conditions that place a heavy load on the cutting edge. Under these machining conditions, the cutting edge is subjected to impacts, which makes it prone to microchipping. Furthermore, thermal wear is likely to occur on the rake face, and mechanical wear is likely to occur on the flank face due to contact with chips.

From the above considerations, it can be inferred that for a cutting tool to have a long tool life, it is important for the cutting edge to have excellent fracture resistance and for the rake face or flank face to have excellent wear resistance. However, because fracture resistance and wear resistance are contradictory properties, it has been difficult to improve fracture resistance and wear resistance in the same coating.

After extensive research, the inventors have discovered that by varying the coating composition on the cutting edge and the rake face or flank of the cutting tool, they have achieved a balanced improvement in fracture resistance on the cutting edge and wear resistance on the rake face or flank, resulting in a cutting tool with a long tool life even under machining conditions that place a heavy load on the cutting edge. One embodiment of the present invention (hereinafter also referred to as "this embodiment") is described below, but this embodiment is not limited to this.

[Embodiment 1: Cutting tool (1)]
According to one embodiment of the present disclosure, there is provided a cutting tool comprising:
1. A cutting tool comprising a substrate and a coating disposed on the substrate,
The cutting tool comprises:
Rake face,
a flank surface connected to the rake surface; and
a cutting edge formed by a boundary portion between the rake face and the flank face,
the coating comprises a TiAlCeN layer;
The TiAlCeN layer is
a first TiAlCeN layer located on the rake face or the flank face;
a second TiAlCeN layer located on the cutting edge;
The composition of the first TiAlCeN layer is Ti _x1 Al _y1 Ce _z1 N,
The composition of the second TiAlCeN layer is Ti _x2 Al _y2 Ce _z2 N,
where:
x1+y1+z1=1,
x2+y2+z2=1,
0.300<y1≦0.700,
0.300<y2≦0.700,
0.010<z1≦0.100,
0<z2≦0.090, and
The cutting tool has z1-z2≧0.010.

The cutting tool disclosed herein has a long tool life even under machining conditions that place a heavy load on the cutting edge. The reasons for this are believed to be as follows (i) to (iii).

(i) In the cutting tool of this embodiment, the composition of the first TiAlCeN layer located on the rake face or flank face is Ti _x1 Al _y1 Ce _z1 N, where x1 + y1 + z1 = 1, 0.300 < y1 ≦ 0.700, and 0.010 < z1 ≦ 0.100. That is, the first TiAlCeN layer contains more than 30 atomic % and not more than 70 atomic % of Al and more than 1.0 atomic % and not more than 10.0 atomic % of Ce, relative to the total number of titanium (Ti), aluminum (Al), and cerium (Ce) atoms. This allows the first TiAlCeN layer to have excellent heat resistance and wear resistance. Therefore, when the first TiAlCeN layer is located on the rake face, the excellent heat resistance of the first TiAlCeN layer suppresses plastic deformation of the substrate and oxidation of the coating, thereby suppressing thermal wear of the rake face. Also, when the first TiAlCeN layer is located on the flank face, the excellent wear resistance of the first TiAlCeN layer suppresses mechanical wear of the flank face and also suppresses the growth of thermal cracks.

(ii) In the cutting tool of this embodiment, the ratio z1 of the number of Ce atoms to the total number of Ti, Al, and Ce atoms in the first TiAlCeN layer and the ratio z2 of the number of Ce atoms to the total number of Ti, Al, and Ce atoms in the second TiAlCeN layer satisfy the relationship z1-z2≧0.010. Therefore, the second TiAlCeN layer has higher toughness than the first TiAlCeN layer. Therefore, the second TiAlCeN layer can suppress the occurrence of microchipping at the cutting edge. Furthermore, it can suppress the growth of thermal cracks that originate from the cutting edge.

(iii) As described above, the cutting tool of this embodiment has a well-balanced improvement in wear resistance on the rake face or flank face and fracture resistance on the cutting edge. Therefore, the cutting tool of the present disclosure can have a long tool life even under machining conditions that place a heavy load on the cutting edge.

<Cutting tool structure>
1, the cutting tool 1 of this embodiment has a surface including an upper surface, a lower surface, and four side surfaces, and has an overall rectangular prism shape that is slightly thin in the vertical direction. Furthermore, the cutting tool 1 has a through hole that penetrates the upper and lower surfaces, and at the boundary portions of the four side surfaces of the cutting tool 1, adjacent side surfaces are connected by arc surfaces.

In the cutting tool 1 of this embodiment, the top and bottom surfaces form the rake face 11, and the four side surfaces (and the arc surfaces connecting them) form the flank face 12. The boundary between the rake face 11 and the flank face 12 functions as the cutting edge 13. In other words, the surfaces of the cutting tool 1 of this embodiment (the top and bottom surfaces, the four side surfaces, the arc surfaces connecting these side surfaces, and the inner peripheral surface of the through hole) include the rake face 11, the flank face 12 connected to the rake face, and the cutting edge 13 consisting of the boundary between the rake face 11 and the flank face 12.

The boundary portion between the rake face 11 and the flank face 12, i.e., the cutting edge 13, refers to "the combined portion of the ridge line E that forms the boundary between the rake face 11 and the flank face 12 and the portions of the rake face 11 and the flank face 12 that are near the ridge line E." The "portions of the rake face 11 and the flank face 12 that are near the ridge line E" are determined by the shape of the cutting edge 13 of the cutting tool 1. Below, we will explain the cases where the cutting tool 1 is a tool with a sharp edge shape, a tool with a honed shape that has been honed, and a tool with a negative land shape that has been negative land.

Figures 2 and 3 show a cutting tool 1 with a sharp edge shape. In such a cutting tool 1 with a sharp edge shape, the "portion of the rake face 11 and flank face 12 near the ridge line E" is defined as the region where the distance (linear distance) D from the ridge line E is 50 μm or less (the region indicated by dotted hatching in Figure 3). Therefore, the cutting edge 13 of the cutting tool 1 with a sharp edge shape is the portion corresponding to the dotted hatched region in Figure 3.

Figures 4 and 5 show a honed-shaped cutting tool 1 that has been honed. In addition to the various parts of the cutting tool 1, Figures 4 and 5 also show an imaginary plane R including the rake face 11, an imaginary plane F including the flank face 12, an imaginary ridge line EE formed by the intersection of imaginary planes R and F, an imaginary boundary line ER defining the boundary between the rake face 11 and imaginary plane R, and an imaginary boundary line EF defining the boundary between the flank face 12 and imaginary plane F. Note that in the case of the honed-shaped cutting tool 1, the above-mentioned "ridge line E" should be read as "imaginary ridge line EE."

In such a honed-shaped cutting tool 1, the "portions of the rake face 11 and flank face 12 near the imaginary ridge line EE" are defined as the area between the imaginary boundary lines ER and EF (the area indicated by dotted hatching in Figure 5). Therefore, the cutting edge 13 of the honed-shaped cutting tool 1 corresponds to the area indicated by dotted hatching in Figure 5.

Figures 6 and 7 show a cutting tool 1 with a negative land shape that has been subjected to negative land machining. In addition to each part of the cutting tool 1, Figures 6 and 7 also show an imaginary plane R including the rake face 11, an imaginary plane F including the flank face 12, an imaginary ridge line EE formed by the intersection of imaginary planes R and F, an imaginary boundary line ER that marks the boundary between the rake face 11 and imaginary plane R, and an imaginary boundary line EF that marks the boundary between the flank face 12 and imaginary plane F. Note that even in the case of a cutting tool 1 with a negative land shape, the above-mentioned "ridge line E" should be read as "imaginary ridge line EE."

In a cutting tool 1 with a negative land shape like this, the "portion of the rake face 11 and flank face 12 near the imaginary ridge line EE" is defined as the area between the imaginary boundary lines ER and EF (the area indicated by dotted hatching in Figure 7). Therefore, the cutting edge 13 in a cutting tool 1 with a negative land shape is the portion corresponding to the area indicated by dotted hatching in Figure 7.

Figures 8 and 9 show a cutting tool 1 with a shape that combines honing and a negative land. In addition to each part of the cutting tool 1, Figures 8 and 9 also show an imaginary plane R including the rake face 11, an imaginary plane F including the flank face 12, an imaginary ridge line EE formed by the intersection of imaginary planes R and F, an imaginary boundary line ER that marks the boundary between the rake face 11 and imaginary plane R, and an imaginary boundary line EF that marks the boundary between the flank face 12 and imaginary plane F. Note that even in a cutting tool 1 with a negative land shape, the above-mentioned "ridge line E" is read as "imaginary ridge line EE." Note that imaginary plane R refers to the plane of the rake face 11 that is closest to the cutting edge 13.

In a cutting tool 1 having this shape, the "portion of the rake face 11 and flank face 12 near the imaginary ridge line EE" is defined as the area between the imaginary boundary lines ER and EF (the area indicated by dotted hatching in Figure 8). Therefore, the cutting edge 13 of the cutting tool 1 corresponds to the area indicated by dotted hatching in Figure 8.

Figure 1 shows cutting tool 1 as an indexable cutting tip for turning, but cutting tool 1 is not limited to this and examples include drills, end mills, indexable cutting tips for drills, indexable cutting tips for end mills, indexable cutting tips for milling, metal saws, gear cutting tools, reamers, taps, etc.

Furthermore, when the cutting tool 1 is an indexable cutting insert or the like, the cutting tool 1 may have or may not have a chip breaker, and the cutting edge 13 may have any of the following shapes: a sharp edge (the ridge where the rake face and flank intersect) (see Figures 1 to 3), a honed edge (a sharp edge with a radius added) (see Figures 4 and 5), a negative land (chamfered) (see Figures 6 and 7), or a combination of honed and negative land (see Figures 8 and 9).

As shown in FIG. 2, the cutting tool 1 includes a substrate 2 and a coating 3 disposed on the substrate 2. The coating 3 may be disposed on a portion of the surface of the substrate 2, or may be disposed on the entire surface of the substrate 2. When the coating 3 is disposed on a portion of the surface of the substrate 2, the portion of the surface of the substrate 2 includes the entire area within a distance (straight-line distance) D of 200 μm from the ridge line E or the virtual ridge line EE. As long as the effects of the present disclosure are achieved, partial variations in the configuration of the coating 3 do not depart from the scope of this embodiment.

<Base material>
As shown in Figures 2 and 3, the substrate 2 of this embodiment has a rake face 2a and a flank 2b. The boundary between the rake face 2a and the flank 2b forms a cutting edge 2c. The "boundary between the rake face 2a and the flank 2b" refers to the "combination of the ridgeline forming the boundary between the rake face 2a and the flank 2b and the portions of the rake face 2a and the flank 2b that are near the ridgeline," similar to the above-mentioned "boundary between the rake face 11 and the flank 12." The "portion near the ridgeline of the rake face 2a and the flank 2b" is defined as described above depending on whether the shape of the cutting edge 13 of the cutting tool 1 is a sharp edge shape, a honed shape, or a negative land shape.

Any conventionally known substrate of this type can be used as the substrate 2. Examples include cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, and cemented carbide containing carbonitrides of Ti, Ta, Nb, etc.), cermets (based on TiC, TiN, TiCN, etc.), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride sintered body, and diamond sintered body. Of these various substrates, WC-based cemented carbide and cermets (especially TiCN-based cermets) are particularly preferred. This is because these substrates offer an excellent balance of hardness and strength, especially at high temperatures, and have excellent properties as substrates for cutting tools.

<Coating>
The coating 3 of the first embodiment has a TiAlCeN layer. The coating 3 of the present embodiment may or may not include other layers, so long as it has a TiAlCeN layer. Examples of other layers include a first layer. As shown in FIG. 10 , the first layer 31 can be provided between the substrate 2 and the TiAlCeN layer 30. In this case, the first layer 31 corresponds to the underlayer 32. The first layer 31 can be provided on the outermost surface of the coating 3. In this case, the first layer 31 corresponds to the surface layer 33. The coating can include one or both of the underlayer 32 and the surface layer 33. Details of the first layer will be described later.

The layer structure of the coating 3 does not need to be uniform across the entire coating 20; the layer structure may vary in parts.

The thickness of the coating 3 is preferably 0.5 μm or more and 15 μm or less. If the coating thickness is less than 0.5 μm, the tool life tends to be insufficient. If the coating thickness is more than 15 μm, stress is generated within the coating during machining, making it more susceptible to peeling or breakage. The coating thickness is more preferably 1.0 μm or more and 12.0 μm or less, and even more preferably 3.0 μm or more and 7.0 μm or less. The method for measuring the coating thickness will be described later.

<TiAlCeN layer>
The TiAlCeN layer of this embodiment has a first TiAlCeN layer located on the rake face 11 or the flank 12, and a second TiAlCeN layer located on the cutting edge 13. That is, one TiAlCeN layer has a region made of the first TiAlCeN layer and a region made of the second TiAlCeN layer.

≪Composition≫
The composition of the first TiAlCeN layer is Ti _x1 Al _y1 Ce _z1 N, and the composition of the second TiAlCeN layer is Ti _x2 Al _y2 Ce _z2 N, where x1, y1, z1, x2, y2, and z2 satisfy the following (1) to (7).
(1) x1+y1+z1=1
(2) x2+y2+z2=1
(3) 0.300<y1≦0.700
(4) 0.300<y2≦0.700
(5) 0.010<z1≦0.100
(6) 0<z2≦0.090
(7) z1-z2≧0.010

From the viewpoint of improving the heat resistance of the first TiAlCeN layer, the lower limit of y1 is greater than 0.300, preferably greater than or equal to 0.310, preferably greater than or equal to 0.320, preferably greater than or equal to 0.350, and more preferably greater than or equal to 0.400. From the viewpoint of improving the hardness of the first TiAlCeN layer, the upper limit of y1 is less than or equal to 0.700, preferably less than or equal to 0.650, preferably less than or equal to 0.630, and more preferably less than or equal to 0.600. From the viewpoint of improving the hardness of the first TiAlCeN layer, y1 is greater than 0.300 and less than or equal to 0.700, preferably greater than or equal to 0.350 and less than or equal to 0.650, and even more preferably greater than or equal to 0.400 and less than or equal to 0.600.

From the viewpoint of improving the wear resistance of the first TiAlCeN layer, the lower limit of z1 is greater than 0.010, preferably greater than or equal to 0.011, preferably greater than or equal to 0.015, and more preferably greater than or equal to 0.020. From the viewpoint of improving the chipping resistance of the first TiAlCeN layer, the upper limit of z1 is less than or equal to 0.100, preferably less than or equal to 0.080, preferably less than or equal to 0.065, preferably less than or equal to 0.060, preferably less than or equal to 0.050, and more preferably less than or equal to 0.030. The above z1 is greater than 0.010 and less than or equal to 0.100, preferably greater than or equal to 0.015 and less than or equal to 0.050, and more preferably greater than or equal to 0.020 and less than or equal to 0.030.

From the viewpoint of improving the heat resistance of the second TiAlCeN layer, the lower limit of y2 is greater than 0.300, preferably greater than or equal to 0.350, and more preferably greater than or equal to 0.400. From the viewpoint of improving the hardness of the second TiAlCeN layer, the upper limit of y2 is less than or equal to 0.700, preferably less than or equal to 0.650, and more preferably less than or equal to 0.600. From the viewpoint of improving the hardness of the second TiAlCeN layer, y2 is greater than 0.300 and less than or equal to 0.700, preferably greater than or equal to 0.350 and less than or equal to 0.650, and even more preferably greater than or equal to 0.400 and less than or equal to 0.600.

From the viewpoint of improving the wear resistance of the second TiAlCeN layer, the lower limit of z2 is greater than 0 and is preferably greater than or equal to 0.001, preferably greater than or equal to 0.002, preferably greater than or equal to 0.005, and more preferably greater than or equal to 0.010. From the viewpoint of improving the chipping resistance of the second TiAlCeN layer, the upper limit of z2 is less than or equal to 0.090, preferably less than or equal to 0.060, preferably less than or equal to 0.040, and more preferably less than or equal to 0.020. z2 is greater than 0 and less than or equal to 0.090, preferably greater than or equal to 0.005 and less than or equal to 0.040, and even more preferably greater than or equal to 0.010 and less than or equal to 0.020.

From the viewpoint of improving the wear resistance and chipping resistance of the TiAlCeN layer in a well-balanced manner, the lower limit of z1-z2 is 0.010 or more, preferably 0.013 or more, preferably 0.015 or more, and preferably 0.020 or more. From the viewpoint of improving the peeling resistance of the TiAlCeN layer, the upper limit of z1-z2 is preferably 0.099 or less, preferably 0.090 or less, preferably 0.050 or less, preferably 0.030 or less, and preferably 0.025 or less. z1-z2 is preferably 0.010 or more and 0.090 or less, more preferably 0.013 or more and 0.050 or less, and even more preferably 0.015 or more and 0.030 or less.

The above x1 can be calculated as x1 = 1 - y1 - z1. The above x2 can be calculated as x2 = 1 - y2 - z2.

The above x1, y1, z1, x2, y2, and z2 can be determined by measuring the composition of each region of the TiAlCeN layer (cutting edge region, rake face region, and flank face region) using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer (SEM-EDS). Specific measurement methods are described below.

(A1) A measurement sample is obtained by cutting the cutting tool 1 so that a cross section along the thickness direction of the coating 3 is exposed. The cutting position is determined as follows, taking into account the actual usage conditions of the cutting tool.

Figures 11 and 12 are diagrams illustrating the cutting position of a cutting tool. When cutting tool 1 is used to cut a workpiece with cutting edge 13 in a corner portion (a portion with an apex angle that forms an arc), as shown in Figure 11, cutting is performed along a line that includes line L1 that bisects the corner portion and exposes a cross section that runs along the thickness direction of coating 3. On the other hand, when cutting tool 1 is used to cut a workpiece with cutting edge 13 in a straight portion (a portion that forms a straight line), cutting is performed along a line that includes line L2 that is perpendicular to the cutting edge of the straight portion and exposes a cross section that runs along the thickness direction of coating 3, as shown in Figure 12. If necessary, the exposed cut surface is polished to make it smooth.

(B1) Observe the above cut surface at 5000x magnification using SEM-EDS, and set three rectangular measurement fields of view, each measuring 15 μm or more in the thickness direction of the coating and 15 μm or more in the direction perpendicular to the thickness direction, so as to include the first TiAlCeN layer located on the rake face or flank face. The thickness direction of the measurement field is set so as to include the entire thickness of the first TiAlCeN layer.

When the measurement field is set to include the first TiAlCeN layer located on the rake face, the measurement field is set so that the first TiAlCeN layer is located on the rake face at a distance of 100 μm or more and 200 μm or less from the ridge line E or the virtual ridge line EE. When the measurement field is set to include the first TiAlCeN layer located on the flank face, the measurement field is set so that the first TiAlCeN layer is located on the flank face at a distance of 100 μm or more and 200 μm or less from the ridge line E or the virtual ridge line EE.

As shown in Figure 13, the three measurement fields are set so that the sides of each measurement field in the thickness direction (the direction indicated by arrow T in Figure 13) are in contact with each other, and so that the measurement fields are continuous. The measurement fields may partially overlap (the overlapping areas are indicated by diagonal lines in Figure 13). In this case, the measurement fields are set so that the length of the overlapping parts of the sides in the direction perpendicular to the thickness direction of each measurement field (the direction indicated by arrow H in Figure 13) is 2 μm or less.

(C1) Identify the region of the first TiAlCeN layer in each of the three measurement fields. Specifically, perform elemental mapping using SEM-EDS for each measurement field to identify the layer containing Ti, Al, and Ce. The identified layer corresponds to the first TiAlCeN layer.

(D1) For each of the three measurement fields, the composition ratios of Al, Ti, and Ce in the first TiAlCeN layer are analyzed, and the Ti ratio x1, Al ratio y1, and Ce ratio z1 relative to the total number of Al, Ti, and Ce atoms are calculated. The average value of x1 in the three measurement fields corresponds to x1 in the composition Ti _x1 Al _y1 Ce _z1 N of the first TiAlCeN layer of this embodiment. The average value of y1 in the three measurement fields corresponds to y1 in the composition Ti _x1 Al _y1 Ce _z1 N of the first TiAlCeN layer of this embodiment. The average value of z1 in the three measurement fields corresponds to z1 in the composition Ti _x1 Al _y1 Ce _z1 N of the first TiAlCeN layer of this embodiment.

The x2, y2, and z2 in the composition Ti _x2 Al _y2 Ce _z2 N of the second TiAlCeN layer located on the cutting edge are measured in the same manner as the x1, y1, and z1 described above, except that the position of the measurement field is set to include the second TiAlCeN layer located on the cutting edge. The measurement field is set so that the second TiAlCeN layer included in the measurement field is the second TiAlCeN layer located on the cutting edge at a distance of 50 μm or less from the ridge line E or the virtual ridge line EE.

The above-mentioned SEM-EDS analysis can be performed using, for example, a scanning electron microscope (S-3400N type, manufactured by Hitachi High-Technologies Corporation) under the following conditions.
Acceleration voltage: 15 kV
Process time: 5
Spectral range: 0 to 20 keV
Number of channels: 1K
Number of frames: 150
X-ray take-off angle: 30°.

It has been confirmed that as long as measurements are taken using the same cutting tool, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

In the composition of the first TiAlCeN layer of this embodiment, Ti _x1 Al _y1 Ce _z1 N, the ratio A _N1 /A _M1 of the number of N atoms A _N1 to the total A _M1 of the number of Ti, Al, and Ce atoms is necessarily in the range of 0.8 to 1.2. In the composition of the second TiAlCeN layer of this embodiment, Ti _x2 Al _y2 Ce _z2 N, the ratio A _N2 /A _M2 of the number of N atoms A _N2 to the total A _M2 of the number of Ti, Al, and Ce atoms is necessarily in the range of 0.8 to 1.2.

The ratios A _N1 /A _M1 and A _N2 /A _M2 can be measured by Rutherford backscattering (RBS) method. It has been confirmed that the effects of the present disclosure are not impaired as long as the ratios A _N1 /A _M1 and A _N2 /A _M2 are within the above-mentioned ranges.

<Thickness>
In this embodiment, the thickness of the TiAlCeN layer is preferably 0.5 μm or more and 15 μm or less. If the thickness of the TiAlCeN layer is less than 0.5 μm, it is difficult to obtain the effect of improving the wear resistance and chipping resistance of the TiAlCeN layer, and the tool life tends to be insufficient. If the thickness of the TiAlCeN layer exceeds 15 μm, stress is generated in the TiAlCeN layer during processing, making it more likely to peel or break. The thickness of the TiAlCeN layer is more preferably 1 μm or more and 12 μm or less, and even more preferably 3 μm or more and 7 μm or less. The thickness of the TiAlCeN layer is measured as follows.

(A2) Using the same method as described in (A1) of the method for measuring the composition of the first TiAlCeN layer, cut the cutting tool so that a cross section along the thickness direction of the coating is exposed, and obtain a measurement sample.

(B2) The cross section is observed at 1500x magnification using a scanning electron microscope (Model S-3400N, manufactured by Hitachi High-Technologies Corporation), and the thickness of the TiAlCeN layer is measured at three random locations on each of the rake face and flank face along the normal direction to the substrate surface. The arithmetic average of these measurements corresponds to the "TiAlCeN layer thickness." The SEM measurement conditions are the same as those described in (D1) of the first method for measuring the composition of the TiAlCeN layer.

It has been confirmed that as long as measurements are taken using the same cutting tool, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

In this embodiment, the thickness of the coating and the thickness of the first layer are also measured using the same procedure as above. It has been confirmed that, as long as these thicknesses are measured using the same cutting tool, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

<Crystal structure>
In this embodiment, the TiAlCeN layer preferably has a cubic crystal structure. This allows the TiAlCeN layer to have high hardness and excellent wear resistance. Here, "the TiAlCeN layer has a cubic crystal structure" means that, when an X-ray diffraction spectrum of the TiAlCeN layer is measured, peaks derived from the cubic crystal structure are observed, and peaks derived from crystal structures other than the cubic crystal structure (e.g., a wurtzite crystal structure) are not observed (i.e., below the detection limit). Such an X-ray diffraction spectrum is measured as follows.

A flat portion of the tool's flank is cut out and fixed in a holder to prepare a sample, which is then polished as necessary to smooth the surface to be measured. If another layer is formed on the TiAlCeN layer, that layer is removed by polishing or other means, and the surface of the TiAlCeN layer is then smoothed. Next, an X-ray diffractometer (XRD) is used to perform X-ray diffraction on the TiAlCeN layer, and an X-ray diffraction spectrum is obtained.

The above-mentioned X-ray diffraction can be measured, for example, using an X-ray diffractometer (SmartLab (registered trademark), manufactured by Rigaku Corporation) under the following conditions.
Diffraction method: θ-2θ method X-ray source: Cu-Kα ray (1.541862 Å)
Detector: D/Tex Ultra 250
Tube voltage: 45 kV
Tube current: 200mA
Scan speed: 20°/min Scan range: 15 to 85°
Slit: 2.0 mm.

≪First layer≫
The coating 3 of this embodiment further includes a first layer, which preferably comprises at least one element selected from a first group consisting of Group 4, Group 5, and Group 6 elements, aluminum, and silicon in the periodic table, or a first compound comprising at least one element selected from Group 1 and at least one element selected from Group 2 consisting of carbon, nitrogen, oxygen, and boron. Elements in Group 4 of the periodic table include titanium (Ti), zirconium (Zr), and hafnium (Hf). Elements in Group 5 of the periodic table include vanadium (V), niobium (Nb), and tantalum (Ta). Elements in Group 6 of the periodic table include chromium (Cr), molybdenum (Mo), and tungsten (W).

The first group preferably consists of titanium, chromium, aluminum, and silicon. That is, the first layer preferably consists of at least one element selected from the group consisting of titanium, chromium, aluminum, and silicon, or a first compound consisting of at least one element selected from the group consisting of titanium, chromium, aluminum, and silicon and at least one element selected from the second group consisting of carbon, nitrogen, oxygen, and boron. This further improves tool life.

Examples of the first compound include TiAlN, TiAlSiCN, TiAlSiON, TiAlSiN, TiCrSiN, TiAlCrSiN, AlCrN, AlCrO, AlCrSiN, TiZrN, TiAlMoN, TiAlNbN, TiSiN, AlCrTaN, AlTiVN, TiB ₂ , TiCrHfN, CrSiWN, TiAlCN, TiSiCN, AlZrON, AlCrCN, AlHfN, CrSiBON, CrAlBN, TiAlWN, AlCrMoCN, TiAlBN, TiAlCrSiBCNO, ZrN, ZrB ₂ , ZrCN, CrSiBN, and AlCrBN.

The first layer can be provided between the substrate and the TiAlCeN layer. In this case, the first layer corresponds to an underlayer. The underlayer can improve adhesion between the substrate and the coating, and also improve the abrasion resistance of the coating. When the first layer is an underlayer, it is preferably made of TiAlN, TiN, or AlCrN. In this case, the thickness of the first layer is preferably 0.2 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less.

The first layer can be provided on the outermost surface of the coating. In this case, the first layer corresponds to a surface layer. The surface layer can improve the thermal crack resistance and wear resistance of the coating. When the first layer is a surface layer, it is preferably made of TiCN, TiAlBN, TiAlSiN, or TiN. In this case, the thickness of the first layer is preferably 0.2 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less.

[Embodiment 2: Cutting tool (2)]
A cutting tool according to an embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") can have the same configuration as Embodiment 1, except that it includes a multilayer structure in which TiAlCeN layers and first layers are alternately stacked. Therefore, the multilayer structure will be described below.

≪Multilayer structure≫
14, the coating 3 of this embodiment preferably includes a multilayer structure in which TiAlCeN layers 30 and first layers 31 are alternately stacked. This structure can suppress the propagation of cracks from the surface of the coating that occur during use of a cutting tool near the interface between the TiAlCeN layer and the first layer, thereby improving the tool life of the cutting tool.

The multilayer structure may include a first multilayer structure in which first TiAlCeN layers and the first layer are alternately stacked, and a second multilayer structure in which second TiAlCeN layers and the first layer are alternately stacked. The first multilayer structure is located on the flank or rake face, and the second multilayer structure is located on the cutting edge.

The number of TiAlCeN layers and first layers is not particularly limited, as long as the multilayer structure includes at least one TiAlCeN layer and at least one first layer. The number of layers refers to the total number of TiAlCeN layers and first layers included in the multilayer structure. The number of layers is preferably 10 to 5,000, more preferably 200 to 5,000, more preferably 400 to 2,000, and even more preferably 500 to 1,000. In the multilayer structure, the layer closest to the substrate may be either the TiAlCeN layer or the first layer. In addition, in the multilayer structure, the layer farthest from the substrate may be either the TiAlCeN layer or the first layer. Here, the TiAlCeN layer refers to the first TiAlCeN layer or the second TiAlCeN layer.

The thickness of the multilayer structure is preferably 0.5 μm or more and 15 μm or less, and more preferably 1 μm or more and 12 μm or less. The thickness of the multilayer structure is measured using the method for measuring the thickness of the TiAlCeN layer described in embodiment 1, but with the multilayer structure as the measurement target.

It has been confirmed that as long as measurements are taken using the same cutting tool, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

In the above multilayer structure, the TiAlCeN layer and the first layer each preferably have a thickness of 2 nm or more and 50 nm or less. By alternately repeating such thin layers, crack propagation can be suppressed, and delamination can also be suppressed. If the thickness of each of the TiAlCeN layer and the first layer is less than 2 nm, the effect of suppressing crack propagation may be reduced. Furthermore, if the thickness of each of the TiAlCeN layer and the first layer exceeds 50 nm, the effect of suppressing delamination may be reduced.

In the above multilayer structure, the thickness of each of the TiAlCeN layer and the first layer is preferably 2 nm or more and 50 nm or less, more preferably 4 nm or more and 40 nm or less, and even more preferably 5 nm or more and 30 nm or less.

The thickness of each of the TiAlCeN layers and the first layer in the above multilayer structure was measured as follows:

(A3) Using the same method as described in (A1) of the method for measuring the composition of the first TiAlCeN layer above, cut the cutting tool so that a cross section along the thickness direction of the coating is exposed, and obtain a measurement sample.

(B3) The above cross section is observed at approximately 1,000,000 magnification using a scanning electron microscope (S-3400N, manufactured by Hitachi High-Technologies Corporation). The thickness of one TiAlCeN layer is measured at three locations. The arithmetic mean value of the thicknesses at the three locations is calculated, and this arithmetic mean value is defined as the thickness of the TiAlCeN layer. The thickness of one first layer is measured at three locations. The arithmetic mean value of the thicknesses at the three locations is calculated, and this arithmetic mean value is defined as the thickness of the first layer.

For each of the three different TiAlCeN layers, measure the thickness of the TiAlCeN layer using the procedure described above. Calculate the arithmetic mean value of the thicknesses of the three TiAlCeN layers. This arithmetic mean value is used as the thickness of the TiAlCeN layer in the multilayer structure. For each of the three different first layers, measure the thickness of the first layer using the procedure described above. Calculate the arithmetic mean value of the thicknesses of the three first layers. This arithmetic mean value is used as the thickness of the first layer in the multilayer structure.

It has been confirmed that as long as measurements are taken using the same cutting tool, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

The composition of the TiAlCeN layer in the multilayer structure is measured using the following procedure. Three measurement fields are set using the same method as steps (A1) to (D1) in the method for measuring the composition (x1, y1, z1, x2, y2, z2) of the TiAlCeN layer described in embodiment 1.

In each measurement field, five layers of the first TiAlCeN layer and five layers of the second TiAlCeN layer are randomly selected and measured, and the average composition of the five layers of each of the first TiAlCeN layer and the second TiAlCeN layer is determined.

The average composition of the five first TiAlCeN layers is taken as the composition of the first TiAlCeN layer in the measurement field. The average composition of the first TiAlCeN layers in the three measurement fields is taken as the composition of the first TiAlCeN layer in the multilayer structure of this embodiment.

The average composition of the five second TiAlCeN layers is taken as the composition of the second TiAlCeN layer in the measurement field. The average composition of the second TiAlCeN layers in the three measurement fields is taken as the composition of the second TiAlCeN layer in the multilayer structure of this embodiment.

It has been confirmed that as long as measurements are taken using the same cutting tool, there is no variation in the measurement results even if the measurement location is selected arbitrarily.

[Embodiment 3: Method for manufacturing a cutting tool]
In embodiment 3, a method for manufacturing the cutting tool of embodiment 1 or embodiment 2 is described. The manufacturing method can include a step of preparing a substrate and a step of forming a coating on the substrate. Details of each step are described below.

<Process of preparing substrate>
In the step of preparing a substrate, a substrate 2 is prepared. The substrate 2 may be the substrate described in the first embodiment.

For example, when using a cemented carbide as the substrate, a commercially available substrate may be used, or it may be manufactured using a general powder metallurgy method. When manufacturing using a general powder metallurgy method, for example, WC powder and Co powder are mixed using a ball mill or the like to obtain a mixed powder. The mixed powder is then dried and molded into a desired shape to obtain a green body. The green body is then sintered to obtain a WC-Co cemented carbide (sintered body). The sintered body is then subjected to a desired cutting edge processing such as honing to produce a substrate made of a WC-Co cemented carbide. Substrates other than those mentioned above can also be prepared as long as they are conventionally known as this type of substrate.

<<Coating Forming Process>>
In the coating forming step, the coating 3 is formed on the substrate 2. In this embodiment, the coating 3 can be formed by a physical vapor deposition (PVD) method. Specific examples of the PVD method include an arc ion plating (AIP) method, a balanced magnetron sputtering (BMS) method, and an unbalanced magnetron sputtering (UBMS) method. In this embodiment, it is preferable to use arc ion plating.

In the AIP method, an arc discharge is generated using a target material as a cathode. This evaporates and ionizes the target material. The ions are then deposited on the surface of a substrate 2 to which a negative bias voltage is applied. The AIP method excels in the ionization rate of the target material. The specific film formation method is as follows:

A target material and substrate are placed in the chamber of the film-forming device. The substrate is held in a rotatable substrate holder. Depending on the composition of the coating to be formed, alloy targets with varying particle sizes of Ti, Al, Ce, etc., or multiple targets with different compositions can be used. The composition of the coating can also be changed by adjusting the reaction gas pressure and/or the rotation speed of the substrate holder.

Then, the surface of the substrate 2 is cleaned by ion bombardment treatment using Ar ions. Conventional known conditions can be used for the ion bombardment treatment.

If the coating includes a first layer as an underlayer, the first layer is formed on the surface of the substrate 2. For example, a TiAlN layer, TiN layer, or AlCrN layer is formed on the surface of the substrate 2. Conventional methods can be used to form the first layer.

Next, after placing the shielding material 50 in the chamber of the film formation device, nitrogen gas is introduced into the chamber, and a TiAlCeN layer is formed on the substrate 2 while the substrate holder holding the substrate 2 is rotated. At this time, the positional relationship between the target material, substrate, and shielding material is adjusted. This positional relationship is explained using Figures 15 and 16.

In Figure 15, the substrate 2 is positioned so that its flank 12 faces the target material 51. Furthermore, the shielding material 50 is positioned so that it faces the rake face 11 of the substrate 2.

By positioning the target material 51, substrate 2, and shielding material 50 in the above-described positional relationship, the presence of the shielding material 50 makes it more difficult for a film to be formed on the rake face 11 and cutting edge 13 than on the flank face 12. Furthermore, because Ce ions have a large ionic radius, they are easily trapped by the shielding material 50. Therefore, the amount of Ce that reaches the rake face 11 and cutting edge 13 is less than the amount of Ce that reaches the flank face 12. As a result, the Ce content (atomic %) in the TiAlCeN layer formed on the rake face 11 and cutting edge 13 is lower than the Ce content (atomic %) in the TiAlCeN layer formed on the flank face 12.

By forming a TiAlCeN layer with the positional relationship of the target material, substrate, and shielding material shown in Figure 15, the TiAlCeN layer can have different compositions on the flank 12 and the cutting edge 13. Furthermore, by using appropriate targets and formation conditions and positioning the shielding material in the above-mentioned relationship, the ratio z1 of Ce to the total number of Ti, Al, and Ce atoms in the TiAlCeN layer located on the flank 12 can be made 0.010 or more greater than the ratio z2 of Ce to the total number of Ti, Al, and Ce atoms in the TiAlCeN layer located on the cutting edge 13.

In Figure 16, the substrate 2 is positioned so that its rake face 11 faces the target material 51. Furthermore, the shielding material 50 is positioned so that it faces the flank face 12 of the substrate 2.

By positioning the target material 51, substrate 2, and shielding material 50 in the above-described positional relationship, the presence of the shielding material 50 makes it more difficult for a film to be formed on the flank 12 and cutting edge 13 than on the rake face 11. Furthermore, because Ce ions have a large ionic radius, they are easily trapped by the shielding material 50. Therefore, the amount of Ce that reaches the flank 12 and cutting edge 13 is less than the amount of Ce that reaches the rake face 11. As a result, the Ce content (atomic %) in the TiAlCeN layer formed on the flank 12 and cutting edge 13 is lower than the Ce content (atomic %) in the TiAlCeN layer formed on the rake face 11.

By forming a TiAlCeN layer with the positional relationship of the target material, substrate, and shielding material shown in Figure 16, the TiAlCeN layer can have different compositions on the rake face 11 and the cutting edge 13. Furthermore, by adopting appropriate targets and formation conditions and positioning the shielding material in the above-described relationship, the ratio z1 of Ce to the total number of Ti, Al, and Ce atoms in the TiAlCeN layer located on the rake face 11 can be made 0.010 or more greater than the ratio z2 of Ce to the total number of Ti, Al, and Ce atoms in the TiAlCeN layer located on the cutting edge 13.

A stainless steel plate can be used as the shielding material 50. The distance between the substrate 2 and the shielding material 50 can be, for example, 1 mm or more and 6 mm or less.

The conditions for forming the TiAlCeN layer can be as follows.
Base material temperature: 450-600℃
Bias voltage: -30 to -100V
Arc current: 100 to 200 A
Reaction gas pressure: 3 to 6 Pa

A multilayer structure in which TiAlCeN layers and first layers are alternately stacked can be formed by placing a target for depositing the TiAlCeN layer and a target for depositing the first layer in a chamber and setting the rotation frequency of the rotating holder to, for example, 2 to 5 rpm.

Next, if the coating includes a first layer as a surface layer, the first layer is formed on the surface of the TiAlCeN layer. For example, a TiCN layer, TiAlBN layer, TiAlSiN layer, or TiN layer is formed on the surface of the TiAlCeN layer. Conventional methods can be used to form the first layer.

As a result of the above, a cutting tool 1 can be manufactured that includes a substrate 2 and a coating 3 provided on the substrate 2.

[Appendix 1]
1. A cutting tool comprising a substrate and a coating disposed on the substrate,
The cutting tool comprises:
Rake face,
a flank surface connected to the rake surface; and
a cutting edge formed by a boundary portion between the rake face and the flank face,
the coating comprises a TiAlCeN layer;
The TiAlCeN layer is
a first TiAlCeN layer located on the rake face or the flank face;
a second TiAlCeN layer located on the cutting edge;
The composition of the first TiAlCeN layer is Ti _x1 Al _y1 Ce _z1 ,
The composition of the second TiAlCeN layer is Ti _x2 Al _y2 Ce _z2 ,
where:
x1+y1+z1=1,
x2+y2+z2=1,
0.300<y1≦0.700,
0.300<y2≦0.700,
0.010<z1≦0.100,
0<z2≦0.090, and
A cutting tool, wherein z1-z2≧0.010.

[Appendix 2]
2. The cutting tool of claim 1, wherein the TiAlCeN layer has a thickness of 0.5 μm or more and 15 μm or less.

[Appendix 3]
the coating further comprises a first layer;
The first layer is
at least one element selected from the first group consisting of Group 4 elements, Group 5 elements, Group 6 elements, aluminum, and silicon of the periodic table; or
3. The cutting tool according to claim 1 or 2, comprising a first compound comprising at least one element selected from the first group and at least one element selected from a second group consisting of carbon, nitrogen, oxygen, and boron.

[Appendix 4]
4. The cutting tool of claim 3, wherein the first group consists of titanium, chromium, aluminum, and silicon.

[Appendix 5]
5. The cutting tool according to claim 1, wherein the coating has a thickness of 0.5 μm or more and 15 μm or less.

[Appendix 6]
5. The cutting tool of claim 3 or 4, wherein the coating includes a multilayer structure in which the TiAlCeN layers and the first layers are alternately stacked.

This embodiment will be explained in more detail using examples. However, these examples do not limit the present embodiment.

[Example 1]
<Cutting tool manufacturing>
Cutting tools were produced and their tool lives were evaluated as follows.
<Process of preparing substrate>
As a substrate, a turning tip made of P20 cemented carbide (model number: CNMG120408N (manufactured by Sumitomo Electric Hardmetal Corp.)) described in JIS B 4053: 2013 was prepared. The substrate was placed on a substrate holder of an arc ion plating device.

<<Coating Forming Process>>
As target materials, sintered alloys were prepared having the compositions shown in the "TiAlCeN layer" and "first layer" columns of "target material composition" in Table 1. For example, for sample 5, a sintered alloy having an atomic ratio of "Ti:Al:Ce=0.55:0.35:0.10" was prepared as the target material for forming the TiAlCeN layer (hereinafter also referred to as the "TiAlCeN layer target"), and a sintered alloy having an atomic ratio of "Ti:Al:B=0.50:0.45:0.05" was prepared as the target material for forming the first layer (hereinafter also referred to as the "first layer target").

The above target material was placed in the arc evaporation source of an arc ion plating device. When two types of target materials were used, they were placed in different arc evaporation sources. Next, the chamber of the device was evacuated to a vacuum of 0.5 Pa or less and the substrate was heated to 450°C. Ar gas was then introduced into the chamber to create an Ar atmosphere of 2.5 Pa. In this state, a bias voltage of -800 V was applied to the substrate, and ion bombardment treatment using Ar gas was performed to clean the surface of the substrate.

(Samples 1 to 3, Samples 7 to 10, Samples 12 to 15)
Next, a shielding material was placed in the chamber. The positional relationship between the target material, substrate, and shielding material was as shown in Fig. 16. That is, the substrate 2 was placed so that its rake face 11 faced the target material 51. The shielding material 50 was placed so that it faced the flank face 12 of the substrate 2. The distance between the shielding material 50 and the substrate 2 was 3 mm.

Next, nitrogen gas was introduced into the chamber to create a reaction atmosphere of 3.5 Pa. In this state, an arc current was discharged on the surface of the TiAlCeN layer target, a bias voltage was applied to the substrate, and a TiAlCeN layer was formed on the substrate while rotating the substrate holder, thereby obtaining a cutting tool. The conditions for forming the TiAlCeN layer were as follows:
Base material temperature: 550℃
Bias voltage: -50V
Arc current: 160A
Reaction gas pressure: 3.5 Pa

(Sample 1-1, Sample 1-6, Sample 1-7)
Using the target for the TiAlCeN layer of each sample, a TiAlCeN layer was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure) as those of Sample 1, except that no shielding material was installed, to obtain a cutting tool.

(Sample 4)
Using the target for the TiAlCeN layer of Sample 4, a TiAlCeN layer was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure, presence of a shielding material, distance between the shielding material and the substrate) as those of Sample 1. Next, using the target for the first layer, nitrogen gas and methane gas were introduced from the gas inlet, and a first layer (TiCN layer) was formed as a surface layer on the TiAlCeN layer while rotating the substrate holder, thereby obtaining a cutting tool.

(Sample 5)
Using the target for the TiAlCeN layer of Sample 5, a TiAlCeN layer was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reactive gas composition, reactive gas pressure, presence of a shielding material, distance between the shielding material and the substrate) as those of Sample 1. Next, using the target for the first layer, nitrogen gas was introduced from the gas inlet, and a first layer (TiAlBN layer) was formed as a surface layer on the TiAlCeN layer while rotating the substrate holder, thereby obtaining a cutting tool.

(Sample 11)
Nitrogen gas was introduced into the chamber to create an atmosphere of 3.5 Pa. In this state, an arc current was discharged on the surface of the first layer target, a bias voltage was applied to the substrate side, and a first layer (TiAlN layer) was formed as an underlayer on the surface of the substrate while the substrate holder was rotated.

Next, using the target for the TiAlCeN layer of sample 11, a TiAlCeN layer was formed on the substrate under the same formation conditions as sample 1 (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure, presence of shielding material, distance between shielding material and substrate), to obtain a cutting tool.

(Sample 6)
The target for the TiAlCeN layer and the target for the first layer of sample 6 were arranged adjacent to each other in the chamber. That is, the target for the TiAlCeN layer and the target for the first layer were arranged so that, when the substrate holder rotated, the positional relationship between the target for the TiAlCeN layer and the substrate 2 was the same as the positional relationship between the target for the first layer and the substrate 2.

Next, a shielding material was placed inside the chamber. The positional relationship between the target material, substrate, and shielding material was as shown in Figure 16.

Next, while the substrate holder was rotating at 5 rpm, TiAlCeN layers and AlCrN layers were alternately formed on the substrate under the same formation conditions as Sample 1 (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure, distance between the shielding material and the substrate), forming a coating with a multilayer structure and obtaining a cutting tool.

(Sample 1-2, Sample 1-3)
A TiAlCeN layer was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure) as those for Sample 1, except that a target for the TiAlCeN layer of each sample was used and the distance between the shielding material and the substrate was set to 0.5 mm, thereby obtaining a cutting tool.

(Samples 1-4)
Using the target for the TiAlCeN layer and the target for the first layer of Sample 1-4, a coating having a multilayer structure was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure, distance between the shielding material and the substrate) as those of Sample 6, except that no shielding material was provided, and a cutting tool was obtained.

<Evaluation>
<Coating composition>
For the TiAlCeN layers of the cutting tools of each sample obtained, the composition of the first TiAlCeN layer located on the rake face, Ti _x1 Al _y1 Ce _z1 N, and the composition of the second TiAlCeN layer located on the cutting edge, Ti _x2 Al _y2 Ce _z2 N, were measured. Specific measurement methods are as shown in Embodiments 1 and 2. The results are shown in Table 2 in the "x1,""y1," and "z1" columns for "First TiAlCeN Layer (Rake Face)" and the "x2,""y2," and "z2" columns for "Second TiAlCeN Layer." Furthermore, the value of "z1 - z2" is also shown in Table 2. It was confirmed that x1 + y1 + z1 = 1 and x2 + y2 + z2 = 1 for all samples. Furthermore, in all the samples, it was confirmed that the ratio A _N1 /A _M1 of the number of N atoms A _N1 to the total A _M1 of the number of Ti, Al, and Ce atoms in _the composition Ti _x1 Al _y1 Ce z1 N of the first TiAlCeN layer, and the ratio A _N2 /A _M2 of the number of N atoms A _N2 to the total A _M2 of the number of Ti, Al, and Ce atoms in the composition Ti _x2 Al _y2 Ce _z2 N of the second TiAlCeN layer were in the range of 0.8 to 1.2.

The thickness of the TiAlCeN layer, first layer, and total coating thickness of each cutting tool sample was measured. Specific measurement methods are as described in Embodiments 1 and 2. The results are shown in the "TiAlCeN layer," "First layer (base layer)," "First layer (surface layer)," and "Total coating thickness" columns under "Thickness (μm)" in Table 2. The description "Multilayer structure (6.0 μm) TiAlCeN layer (6 nm)/AlCrN layer (6 nm)" for Sample 6 and Samples 1-4 indicates that the coating includes a multilayer structure in which 6 nm-thick TiAlCeN layers and 6 nm-thick AlCrN layers are alternately stacked, and that the total thickness of the multilayer structure is 6.0 μm.

The crystalline structure of the TiAlCeN layer of each cutting tool sample was measured. It was confirmed that the TiAlCeN layer in all samples had a cubic crystalline structure.

<Cutting test>
A cutting test was performed using each sample cutting tool under the following conditions, and the cutting time (minutes) was measured until the crater wear width reached 0.5 mm or until chipping of the cutting edge occurred. The longer the cutting time, the longer the tool life of the cutting tool was determined to be. The results are shown in the "Cutting Test" column in Table 2.

(Cutting conditions)
Work material: SCM435 round bar Cutting speed Vc: 250m/min
Feed rate fz: 0.2 mm/rev
Cutting depth ap: 1.5 mm
Wet cutting The above cutting conditions place a heavy load on the cutting edge, which makes it easy for thermal wear to occur on the rake face.

<Consideration>
The cutting tools of Samples 1 to 15 correspond to Examples. The cutting tools of Samples 1-1 to 1-7 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 1 to 15 (Examples) had longer tool life than the cutting tools of Samples 1-1 to 1-7 (Comparative Examples).

Samples 1-2 and 1-3 used a shielding material when forming the TiAlCeN layer, but "z1 - z2" was less than 0.010 (0.008), making them comparative examples. This is presumably because the amount of Ce contained in the target composition was small, resulting in a small absolute amount reaching the substrate. Additionally, the distance between the shielding material and the substrate was set to 0.5 mm, which meant that the influence of the shielding material extended to the rake face, making it difficult to detect a difference in the amount of Ce between the rake face and flank face.

[Example 2]
<Cutting tool manufacturing>
Cutting tools were produced and their tool lives were evaluated as follows.
<Process of preparing substrate>
As a substrate, a cutting tip for milling made of P20 cemented carbide (model number: SEET13T3AGSN (manufactured by Sumitomo Electric Hardmetal Corp.)) described in JIS B 4053: 2013 was prepared. The substrate was placed on a substrate holder of an arc ion plating device.

≪Coating process≫

A sintered alloy having the composition shown in the "TiAlCeN layer" and "First layer" columns under "Target material composition" in Table 3 was prepared as the target material.

The above target material was placed in the arc evaporation source of an arc ion plating device. Next, the chamber of the device was evacuated to a vacuum of 0.5 Pa or less, and the substrate temperature was heated to 450°C. Ar gas was then introduced into the chamber to create an Ar atmosphere of 2.5 Pa. In this state, a bias voltage of -800 V was applied to the substrate, and ion bombardment treatment using Ar gas was performed, cleaning the surface of the substrate.

(Sample 101, Sample 102, Samples 105 to 108, Samples 110 to 112, Sample 2-2, Sample 2-3)
Next, a shielding material was placed in the chamber. The positional relationship between the target material, substrate, and shielding material was as shown in Fig. 15. That is, the substrate 2 was placed so that its flank 12 faced the target material 51. The shielding material 50 was placed so that it faced the rake face 11 of the substrate 2. The distance between the shielding material 50 and the substrate 2 was 4 mm.

Next, nitrogen gas was introduced into the chamber to create a reaction atmosphere of 3.5 Pa. In this state, an arc current was discharged on the surface of the TiAlCeN layer target, a bias voltage was applied to the substrate, and a TiAlCeN layer was formed on the substrate while rotating the substrate holder, thereby obtaining a cutting tool. The conditions for forming the TiAlCeN layer were as follows:
Base material temperature: 500℃
Bias voltage: -100V
Arc current: 190A
Reaction gas pressure: 3.5 Pa

(Sample 2-4, Sample 2-5)
Using the target for the TiAlCeN layer of each sample, a TiAlCeN layer was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure) as those of Sample 101, except that no shielding material was installed, to obtain a cutting tool.

(Sample 103)
Using the target for the TiAlCeN layer of sample 103, a TiAlCeN layer was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure, distance between the shielding material and the substrate) as those of sample 1. Next, using the target for the first layer, nitrogen gas was introduced from the gas inlet, and a first layer (TiAlSiN layer) was formed as a surface layer on the TiAlCeN layer while rotating the substrate holder, thereby obtaining a cutting tool.

(Sample 109)
Nitrogen gas was introduced into the chamber to create an atmosphere of 3.5 Pa. In this state, an arc current was discharged on the surface of the first layer target, a bias voltage was applied to the substrate side, and a first layer (TiN layer) was formed as an underlayer on the surface of the substrate while the substrate holder was rotated.

Next, using the target for the TiAlCeN layer of sample 109, a TiAlCeN layer was formed on the substrate under the same formation conditions as sample 101 (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure, distance between the shielding material and the substrate), to obtain a cutting tool.

(Sample 104)
The target for the TiAlCeN layer of sample 104 and the target for the first layer were arranged adjacent to each other in the chamber. That is, the target for the TiAlCeN layer and the target for the first layer were arranged so that, when the substrate holder was rotated, the positional relationship between the target for the TiAlCeN layer and the substrate 2 was the same as the positional relationship between the target for the first layer and the substrate 2.

Next, a shielding material was placed inside the chamber. The positional relationship between the target material, substrate, and shielding material was as shown in Figure 15.

Next, while the substrate holder was rotating at 5 rpm, TiAlCeN layers and AlCrN layers were alternately laminated on the substrate under the same formation conditions as Sample 1 (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure, distance between the shielding material and the substrate), forming a coating with a multilayer structure and obtaining a cutting tool.

(Sample 2-1)
A multilayer coating was formed on the substrate under the same formation conditions (substrate temperature, bias voltage, arc current, reaction gas composition, reaction gas pressure) as those for Sample 104, except that no shielding material was installed, to obtain a cutting tool.

<Evaluation>
<Coating composition>
For the TiAlCeN layers of the obtained cutting tools of each sample, the composition of the first TiAlCeN layer located on the flank face, Ti _x1 Al _y1 Ce _z1 N, and the composition of the second TiAlCeN layer located on the cutting edge, Ti _x2 Al _y2 Ce _z2 N, were measured. Specific measurement methods are as shown in Embodiments 1 and 2. The results are shown in Table 4 in the "x1,""y1," and "z1" columns for "First TiAlCeN Layer" and the "x2,""y2," and "z2" columns for "Second TiAlCeN Layer." Furthermore, the value of "z1 - z2" is also shown in Table 4. It was confirmed that x1 + y1 + z1 = 1 and x2 + y2 + z2 = 1 for all samples. Furthermore, in all the samples, it was confirmed that the ratio A _N1 /A _M1 of the number of N atoms A _N1 to the total A _M1 of the number of Ti, Al, and Ce atoms in _the composition Ti _x1 Al _y1 Ce z1 N of the first TiAlCeN layer, and the ratio A _N2 /A _M2 of the number of N atoms A _N2 to the total A _M2 of the number of Ti, Al, and Ce atoms in the composition Ti _x2 Al _y2 Ce _z2 N of the second TiAlCeN layer were in the range of 0.8 to 1.2.

The thickness of the TiAlCeN layer, first layer, and total coating thickness of each cutting tool sample was measured. Specific measurement methods are as described in Embodiments 1 and 2. The results are shown in Table 4 under "Thickness (μm)" in the "TiAlCeN layer," "First layer (base layer)," "Second layer (surface layer)," and "Total coating thickness" columns. The description "Multilayer structure (5.0 μm) TiAlCeN layer (6 nm)/AlCrN layer (7 nm)" for Sample 104 and Sample 2-1 indicates that the coating includes a multilayer structure in which 6 nm-thick TiAlCeN layers and 7 nm-thick AlCrN layers are alternately stacked, and that the total thickness of the multilayer structure is 5.0 μm.

The crystalline structure of the TiAlCeN layer of each cutting tool sample was measured. It was confirmed that the TiAlCeN layer in all samples had a cubic crystalline structure.

<Cutting test>
A cutting test was performed using each sample cutting tool under the following conditions, and the cutting distance (m) was measured until the wear width on the flank side reached 200 μm or the thermal crack reached 200 μm. The longer the cutting distance, the longer the tool life of the cutting tool was determined to be. The results are shown in the "Cutting Test" column in Table 4.

(Cutting conditions)
Workpiece: SCM435H block material Cutting speed Vc: 350 m/min
Feed rate fz: 0.2 mm/rev
Cutting depth ap: 2.0 mm
Dry cutting The above cutting conditions place a heavy load on the cutting edge, which makes it easy for mechanical wear and thermal cracks to occur on the flank.

<Consideration>
The cutting tools of Samples 101 to 112 correspond to Examples. The cutting tools of Samples 2-1 to 2-5 correspond to Comparative Examples. It was confirmed that the cutting tools of Samples 101 to 112 (Examples) had longer tool life than the cutting tools of Samples 2-1 to 2-5 (Comparative Examples).

Although the embodiments and examples of the present disclosure have been described above, it is originally intended that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways.
The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the above-described embodiments and examples, and it is intended to include any modifications within the scope of the claims that are equivalent to the claims.

REFERENCE SIGNS LIST 1 Cutting tool 2 Base material 2a Rake face 2b Flank face 2c Cutting edge 3 Coating 11 Rake face 12 Flank face 13 Cutting edge 30 TiAlCeN layer 31 First layer 32 Underlayer 33 Surface layer 50 Shielding material 51 Target material 52 Chamber

Claims (6)

1. A cutting tool comprising a substrate and a coating disposed on the substrate,
The cutting tool comprises:
Rake face,
a flank surface connected to the rake surface; and
a cutting edge formed by a boundary portion between the rake face and the flank face,
the coating comprises a TiAlCeN layer;
The TiAlCeN layer is
a first TiAlCeN layer located on the rake face or the flank face;
a second TiAlCeN layer located on the cutting edge;
The composition of the first TiAlCeN layer is Ti _x1 Al _y1 Ce _z1 N,
The composition of the second TiAlCeN layer is Ti _x2 Al _y2 Ce _z2 N,
where:
x1+y1+z1=1,
x2+y2+z2=1,
0.300<y1≦0.700,
0.300<y2≦0.700,
0.010<z1≦0.100,
0<z2≦0.090, and
A cutting tool, wherein z1-z2≧0.010. The cutting tool described in claim 1, wherein the thickness of the TiAlCeN layer is 0.5 μm or more and 15 μm or less. the coating further comprises a first layer;
The first layer is
at least one element selected from the first group consisting of Group 4 elements, Group 5 elements, Group 6 elements, aluminum, and silicon of the periodic table; or
3. The cutting tool according to claim 1, comprising a first compound comprising at least one element selected from the first group and at least one element selected from a second group consisting of carbon, nitrogen, oxygen, and boron. The cutting tool of claim 3, wherein the first group consists of titanium, chromium, aluminum, and silicon. A cutting tool according to claim 1 or claim 2, wherein the coating has a thickness of 0.5 μm or more and 15 μm or less. The cutting tool described in claim 3, wherein the coating includes a multilayer structure in which the TiAlCeN layers and the first layers are alternately stacked.