JP7142098B2 - coated tools and cutting tools - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to coated tools used for cutting.

As a coated tool used for cutting such as turning and milling, for example, the coated tool described in Patent Document 1 is known. In the cutting tool described in Patent Document 1, a layer containing a compound of titanium (Ti) (titanium compound layer) and aluminum oxide (Al ₂ O ₃ ) are included on the surface of a substrate made of cemented carbide or the like. A coated tool is described which is provided with a coating layer with a layer (aluminum oxide layer). In the coated tool described in Patent Document 1, a plurality of pores are formed at the interface between the titanium compound layer and the aluminum oxide layer, and it is described that these pores provide an impact mitigation effect. .

In Patent Document 2, in a corresponding grain boundary distribution graph showing the ratio of corresponding grain boundaries composed of each constituent atom shared lattice point form to the total corresponding grain boundary length of Σ3 to Σ29 types in aluminum oxide crystals, Σ3 to Within the range of the Σ29 type, the Σ3 type has the highest peak, and the distribution ratio of the Σ3 type within the range of the Σ3 to Σ29 type is 70% or more, so that the grain boundary strength between the aluminum oxide crystals is increased. It is described that it exhibits excellent peeling resistance and chipping resistance in high-speed interrupted cutting.

As described in these patent documents, in coated tools, the impact resistance of the coating layer is increased.

JP 2015-182209 A JP 2016-005862 A

A coated tool of the present disclosure comprises a substrate having a first surface and a coating layer overlying at least the first surface of the substrate. The coating layer includes a first layer containing a titanium compound located on the first surface and a second layer containing a plurality of α-aluminum oxide crystals located on and in contact with the first layer. and In the cross section orthogonal to the first surface, the second layer has a grain boundary length that accounts for the sum of the lengths of the Σ3 to Σ29 grain boundaries in the grain boundaries of the α-aluminum oxide crystal, The Σ3 type has the longest grain boundary length. The coating layer has a plurality of pores arranged in a direction along a boundary between the first layer and the second layer in the first layer. An average width of the pores along the boundary is smaller than an average spacing between adjacent pores.

A cutting tool of the present disclosure is a rod-shaped holder extending from a first end toward a second end, and includes a holder having a pocket located on the side of the first end, and the above-described coated tool located in the pocket. have.

1 is a perspective view of a coated tool of the present disclosure; FIG. FIG. 2 is a sectional view of the AA section in the coated tool shown in FIG. 1; 3 is an enlarged view of the vicinity of the coating layer in the coated tool shown in FIG. 2; FIG. 4 is an enlarged view showing an example of a region B1 shown in FIG. 3; FIG. 4 is an enlarged view showing another example of region B1 shown in FIG. 3; FIG. 1 is a plan view of a cutting tool of the present disclosure; FIG. 7 is an enlarged view of a region B2 shown in FIG. 6; FIG.

Hereinafter, the coated tool 1 of the present disclosure will be described in detail with reference to the drawings. However, each drawing referred to below shows only the main members necessary for the explanation in a simplified manner for convenience of explanation. Accordingly, the coated tool may comprise any components not shown in the referenced figures. Also, the dimensions of the members in each drawing do not faithfully represent the actual dimensions of the constituent members, the dimensional ratios of the respective members, and the like.

<Coated tool>
As shown in FIGS. 1 and 2, the coated tool 1 of the present disclosure comprises a substrate 3 and a coating layer 5. As shown in FIG. The substrate 3 has a first surface 7 (upper surface in FIG. 2), a second surface 9 (side surface in FIG. 2) adjacent to the first surface 7, and at least one edge line where the first surface 7 and the second surface 9 intersect. It has a cutting edge 11 located in the part.

The substrate 3 in the example shown in FIG. 1 has a square plate shape, and the first surface 7 is a square. Therefore, the number of second surfaces 9 is four. At least part of the first surface 7 is a rake face area and at least part of the second surface 9 is a flank area. The shape of the substrate 3 is not limited to a rectangular plate shape, and the first surface 7 may be triangular, pentagonal, hexagonal, or circular, for example. Moreover, the base 3 is not limited to a plate shape, and may be columnar, for example.

The substrate 3 contains, for example, cobalt and nickel as binding phases, and also contains hard phases made of WC, nitrides, and carbonitrides. The average grain size of these hard phases is preferably 3 μm or less, more preferably 1 μm or less, from the viewpoint of increasing hardness.

The covering layer 5 is located on at least the first side 7 of the substrate 3 . The coating layer 5 may be positioned only on the first surface 7 or may be positioned on a surface other than the first surface 7 of the substrate 3 . A covering layer 5 is located on the second side 9 in addition to the first side 7 . The coating layer 5 is provided to improve properties such as wear resistance and chipping resistance of the coated tool 1 during cutting.

The substrate 3 may have a through hole 23 passing through the first surface 7 and a surface located on the opposite side of the first surface 7 . The through hole 23 can be used to insert a fixing member for fixing the coated tool 1 to the holder. Fixing members include, for example, screws and clamping members.

Although the size of the substrate 3 is not particularly limited, for example, the length of one side of the first surface 7 is set to approximately 3 to 20 mm. Moreover, the height from the first surface 7 to the surface located on the opposite side of the first surface 7 is set to about 5 to 20 mm.

The covering layer 5 has a first layer 13 and a second layer 15, as shown in FIG. A first layer 13 is located on the first surface 7 and contains a titanium compound. The second layer 15 is located on and in contact with the first layer 13 and contains a plurality of α-aluminum oxide crystals (Al ₂ O ₃ ).

Titanium compounds contained in the first layer 13 include, for example, carbides, nitrides, oxides, carbonitrides, carbonates, and carbonitrides of titanium. The first layer 13 may be configured to contain only one of the above compounds, or may be configured to contain more than one of the above compounds.

Further, the first layer 13 may have a single-layer structure, or may have a structure in which a plurality of layers are laminated, as long as it contains a titanium compound. For example, the first layer 13 may have a structure in which a titanium nitride layer 17 and a titanium carbonitride layer 19 are laminated. When the first layer 13 has the titanium nitride layer 17, the adhesion between the substrate 3 and the first layer 13 is even higher. Titanium nitride layer 17 and titanium carbonitride layer 19 are mainly composed of titanium nitride and titanium carbonitride, respectively, and may contain other components. In addition, the above-mentioned "main component" means a component having the largest mass % value compared to other components.

The coating layer 5 may be composed only of the first layer 13 and the second layer 15, or may have layers other than these layers. For example, another layer may be present between the substrate 3 and the first layer 13 and another layer may be present above the second layer 15 .

Alternatively, the titanium carbonitride layer 19 may have a structure in which a plurality of regions having different compositions are laminated. For example, the titanium carbonitride layer 19 may have a structure in which a so-called MT (moderate temperature)-first region 19a and a so-called HT (high temperature)-second region 19b are laminated.

When the first layer 13 has the first region 19a and the second region 19b, the first layer 13 may further have an intermediate region 19c between the first region 19a and the second region 19b. Note that the boundaries between the above layers and regions can be specified by observing, for example, SEM photographs or transmission electron microscope (TEM) photographs. The identification can be performed by the ratio of elements constituting each layer, and the difference in crystal size and orientation.

The crystal structure of the aluminum oxide contained in the second layer 15 can be evaluated by, for example, performing X-ray diffraction (XRD: X-Ray Diffraction) analysis and observing the distribution of peak values.

The content ratio of the titanium compound in the first layer 13 and the content ratio of aluminum oxide in the second layer 15 are not limited to specific values. One example is a configuration in which the first layer 13 contains a titanium compound as a main component and the second layer 15 contains aluminum oxide as a main component. Incidentally, the above-mentioned "main component" means a component having the largest mass % value compared to other components, as described above.

The first layer 13 may contain components other than the titanium compound, and the second layer 15 may contain components other than aluminum oxide. For example, when the first layer 13 contains aluminum oxide or the second layer 15 contains a titanium compound, the bondability between the first layer 13 and the second layer 15 is improved.

The coating layer 5 has pores 21 inside the first layer 13, as shown in FIG. Specifically, in a cross section perpendicular to the first surface 7 of the substrate 3, the coating layer 5 is aligned with the first layer 13 in a direction along the boundary 16 between the first layer 13 and the second layer 15. It has a plurality of holes 21 .

In the cross section perpendicular to the first surface 7, the average value of the width w1 of the holes 21 in the direction parallel to the first surface 7 is the distance between the adjacent holes 21, that is, the width w2 of the first portion X. Smaller than average. The coated tool 1 that satisfies such a configuration can obtain high impact resistance in the holes 21 while suppressing a decrease in the strength of the first portion X.

Therefore, it is possible to obtain the effect of mitigating the impact by the holes 21 while suppressing deterioration of the bondability between the first layer 13 and the second layer 15 .

In addition, when evaluating the average value of the width w1 of the holes 21 in the direction parallel to the first surface 7, it is necessary to evaluate the width w1 of all the holes 21 existing in the cross section perpendicular to the first surface 7. Instead, the average value of the width w1 of about 5 to 10 holes 21 positioned side by side in the cross section may be used for evaluation. For example, a 10 μm square area including the boundary 16 between the first layer 13 and the second layer 15 is extracted from the cross section orthogonal to the first surface 7, and the width w1 of the void 21 in this area is measured. Also, the average value of the width w2 of the first portion X may be evaluated by the average value of the intervals of about 5 to 10 holes 21 positioned side by side in the cross section. In addition, in this disclosure, other average values may be defined. Each of these values should be an average value of about 5 to 10 values.

The vacancies 21 need only exist in the first layer 13 . For example, not only the structure located in the first layer 13 as shown in FIG. 4 but also the structure located in each of the first layer 13 and the second layer 15 as shown in FIG. may

Note that the fact that the holes 21 are positioned along the boundary 16 between the first layer 13 and the second layer 15 means that the distance between the plurality of holes 21 and the boundary 16 between the first layer 13 and the second layer 15 is , means that it falls within ±20% of the average value.

From the viewpoint of heat resistance and durability of the coated tool 1 , titanium carbonitride may be contained as the titanium compound contained in the first layer 13 . With such a configuration, the durability of the coated tool 1 is further enhanced when the plurality of pores 21 are located within the first layer 13 .

This is because, although titanium carbonitride has higher hardness than α-aluminum oxide, it has lower impact resistance. This is because the impact resistance of the holes 21 can be enhanced, and the durability of the coated tool 1 can be further enhanced.

Although the size of the holes 21 is not particularly limited, it can be set to 20 to 200 nm, for example. When the size of the holes 21 is 20 nm or more, the impact mitigation effect of the holes 21 can be enhanced. Moreover, when the size of the holes 21 is 200 nm or less, the strength of the first layer 13 can be easily maintained. The size of the hole 21 means the maximum value of the width w1 in the cross section of the hole 21 perpendicular to the first surface 7. As shown in FIG.

The shape of the holes 21 is not particularly limited, but in the cross section orthogonal to the first surface 7, the height h1 in the direction orthogonal to the first surface 7 is parallel to the first surface 7. When the width w1 in the direction is large, in other words, the average value of the width w1 of the holes 21 in the direction parallel to the first surface 7 is the height h1 of the holes 21 in the direction orthogonal to the first surface 7. When it is larger than the average value, the impact resistance can be further improved while suppressing the ratio of the voids 21 . This is for the following reasons.

A cutting load is likely to be applied to the coating layer 5 in a direction orthogonal to the first surface 7 when cutting a work material to manufacture a machined product. At this time, if the hole 21 has a shape in which the width w1 in the direction parallel to the first surface 7 is larger than the height h1 in the direction orthogonal to the first surface 7, the hole 21 is made larger than necessary. Therefore, the cutting load can be absorbed over a wide range of the holes 21. Therefore, the impact resistance can be further improved while suppressing the ratio of the holes 21 . The height h1 of the holes 21 in the direction orthogonal to the first surface 7 is the maximum value of the height h1 of the holes 21 in the direction orthogonal to the first surface 7 .

Specifically, the ratio of the average value of the width w1 of the holes 21 in the direction orthogonal to the first surface 7 to the average value of the height h1 of the holes 21 in the direction parallel to the first surface 7 is 1. When it is 2 or more, the cutting load is easily absorbed in a wide range of the holes 21 . Further, when the above ratio is 2 or less, the amount of deformation of the holes 21 in the direction orthogonal to the first surface 7 is likely to be secured, so that the holes 21 are likely to stably absorb the cutting load. Moreover, the shape of the holes 21 in the cross section may be substantially circular.

When the maximum height of the boundary between the first surface 7 and the second surface 9 in the cross section orthogonal to the first surface 7 is Rz, the height h1 of the holes 21 in the direction orthogonal to the first surface 7 is When the average value is smaller than Rz, deterioration of the durability of the coating layer 5 can be easily suppressed.

The deformation of the first portion X and the plurality of holes 21 located between adjacent holes 21 in the first layer 13 provides the coated tool 1 of the present disclosure with high impact resistance. Here, when the average value of the width of the holes 21 in the direction orthogonal to the first surface 7 is smaller than Rz, the imaginary line connecting the adjacent holes 21 bends more than the width of the holes 21. shown in a zigzag shape.

When the phantom line is shown in the above shape, even if a crack occurs in one of the first portions X, the first portion X located next to the cracked first portion X Cracks do not propagate easily. Therefore, the durability of the coating layer 5 is less likely to deteriorate.

Further, in the cross section perpendicular to the first surface 7, the average value of the distance d1 from the hole 21 to the boundary 16 between the first layer 13 and the second layer 15 is larger than the average value of the width w2 of the first portion X. Even in this case, the durability of the coating layer 5 is less likely to deteriorate. The distance d1 from the hole 21 to the boundary 16 between the first layer 13 and the second layer 15 is the minimum distance from the hole 21 to the boundary 16 .

This is because, in the above case, a sufficient distance from the holes 21 to the boundary 16 between the first layer 13 and the second layer 15 can be secured as compared with the first portion X. This is because even if a crack occurs in one layer, the crack hardly reaches the boundary 16 between the first layer 13 and the second layer 15 . Since the cracks described above do not easily reach the boundary 16 between the first layer 13 and the second layer 15, the bondability between the first layer 13 and the second layer 15 is unlikely to deteriorate.

The pores 21 are located in the first layer 13 and are located away from the boundary between the first layer 13 and the second layer 15 . Here, in the cross section perpendicular to the first surface 7, the average value of the distance d1 from the holes 21 to the boundary 16 between the first layer 13 and the second layer 15 is the number of holes in the direction perpendicular to the first surface 7 21, the bondability between the first layer 13 and the second layer 15 is less likely to decrease while the impact resistance of the coating layer 5 is increased.

This is because the distance from the hole 21 to the boundary 16 between the first layer 13 and the second layer 15 can be sufficiently secured compared to the size of the hole 21, so that the hole 21 deforms to absorb the cutting load. Even in this case, the boundary 16 between the first layer 13 and the second layer 15 is not deformed, or the amount of deformation is sufficiently small. Since the boundary 16 between the first layer 13 and the second layer 15 is less likely to be greatly deformed, the bondability between the first layer 13 and the second layer 15 is less likely to deteriorate.

A second layer 15 located on the first layer 13 contains a plurality of α-aluminum oxide crystals. The thickness of the second layer is preferably 2 to 20 μm, for example.

The second layer 15 of the coated tool 1 of the present disclosure, in a cross-section perpendicular to the first surface 7 of the substrate 3, was measured using a field emission scanning electron microscope and an electron backscatter diffraction device to measure crystal When individual grains are irradiated with an electron beam and the corresponding grain boundaries are measured from the grain boundaries of α-aluminum oxide crystals, The Σ3 type has the longest grain boundary length. The second layer 15 having such a structure has excellent peeling resistance and chipping resistance. The cross section of the substrate 3 should be observed as a polished surface.

The above-mentioned corresponding grain boundaries can be measured with an apparatus that combines a field emission scanning electron microscope (FE-SEM) with an electron beam backscattering diffractometer (EBSD). For the FE-SEM, for example, JSM-7100F manufactured by JEOL Ltd. may be used.

In the coated tool 1 of the present disclosure, corresponding grain boundaries include Σ3 type, Σ7 type, Σ11 type, Σ17 type, Σ19 type, Σ21 type, Σ23 type, and Σ29 type.

In the coated tool 1 of the present disclosure, the ratio of the Σ3 type grain boundary length to the total length of the Σ3 to Σ29 type grain boundaries may be 60% or more. With such a configuration, it has even better impact resistance.

Since the coated tool 1 of the present disclosure includes the first layer 13 and the second layer 15 having excellent impact resistance, it exhibits even better impact resistance.

<Cutting tool>
Next, the cutting tool 101 of the present disclosure will be described with reference to the drawings.

The cutting tool 101 of the present disclosure, as shown in FIGS. 6 and 7, is a rod-shaped body extending from a first end (top in FIG. 6) toward a second end (bottom in FIG. 6). It comprises a holder 105 with a pocket 103 located on the side and the above-described coated tool 1 located in the pocket 103 . In the cutting tool 101 of the present disclosure, the coated tool 1 is attached so that the portion of the ridgeline that is used as the cutting edge protrudes from the tip of the holder 105 .

The pocket 103 is a portion to which the covered tool 1 is mounted, and has a seating surface parallel to the lower surface of the holder 105 and a restraining side surface inclined with respect to the seating surface. Also, the pocket 103 is open on the first end side of the holder 105 .

A coated tool 1 is positioned in the pocket 103 . At this time, the lower surface of the covered tool 1 may be in direct contact with the pocket 103 , or a sheet may be sandwiched between the covered tool 1 and the pocket 103 .

The coated tool 1 is mounted so that the portion of the ridge used as the cutting edge protrudes outward from the holder 105 . The coated tool 1 is attached to the holder 105 by screws 107 . That is, by inserting a screw 107 into the through hole 23 of the coated tool 1, inserting the tip of the screw 107 into a screw hole (not shown) formed in the pocket 103, and screwing the threaded portions together, the coated tool can be obtained. 1 is attached to the holder 105 .

Steel, cast iron, or the like can be used as the holder 105 . In particular, among these members, it is preferable to use steel with high toughness.

The examples shown in FIGS. 6 and 7 illustrate cutting tools used for so-called lathe turning. Turning includes, for example, inner diameter machining, outer diameter machining, and grooving. The cutting tools are not limited to those used for turning. For example, the coated tool 1 of the above embodiment may be used as a cutting tool used for milling.

<Manufacturing method>
Next, an example of a method for manufacturing a coated tool according to the present disclosure will be described.

First, metal powder, carbon powder, etc. are added and mixed as appropriate to an inorganic powder selected from carbides, nitrides, carbonitrides, oxides, etc. that can form a hard alloy that will be the base 3 by firing, to obtain a mixed powder. to make. Next, this mixed powder is molded into a predetermined tool shape using a known molding method to produce a compact. Examples of molding methods include press molding, cast molding, extrusion molding, and cold isostatic press molding. The substrate 3 is produced by firing the above compact in vacuum or in a non-oxidizing atmosphere. Incidentally, the surface of the substrate 3 may be subjected to polishing and honing as required.

Incidentally, the surface of the substrate 3 may be subjected to polishing and honing as required.

Next, a coating layer 5 is formed on the surface of the substrate 3 by a chemical vapor deposition (CVD) method.

First, the layer 17 (base layer) containing titanium nitride in the first layer 13 is formed. Hydrogen (H ₂ ) gas is mixed with 0.5 to 10% by volume of titanium tetrachloride gas and 10 to 60% by volume of nitrogen gas to prepare a first mixed gas used as a reaction gas. A first mixed gas is introduced into the chamber at a gas partial pressure of 10 to 20 kPa, and a layer 17 containing titanium nitride is formed in a temperature range of 830 to 870.degree.

Next, the first region 19a in the first layer 13 is formed. Hydrogen gas is mixed with 0.5 to 10% by volume of titanium tetrachloride gas, 5 to 60% by volume of nitrogen gas, and 0.1 to 3% by volume of acetonitrile gas to prepare a second mixed gas. do. A second mixed gas is introduced into the chamber at a gas partial pressure of 6 to 12 kPa, and a first region 19a containing MT-titanium carbonitride is formed in a temperature range of 830 to 870.degree.

Next, the intermediate region 19c is deposited. Hydrogen gas, 3% to 30% by volume titanium tetrachloride gas, 3% to 15% by volume methane gas, 5% to 10% by volume nitrogen gas, and 0.5% to 5% by volume is mixed with carbon dioxide (CO ₂ ) gas to prepare a third mixed gas. A third mixed gas is introduced into the chamber at a gas partial pressure of 6 to 12 kPa, and an intermediate region 19c having a thickness of about 50 to 300 nm is formed in a temperature range of 900 to 1050.degree. Pores 21 are formed in this intermediate region 19c because the third mixed gas contains carbon dioxide gas. Under the above conditions, in the cross section orthogonal to the first surface 7, the average width w1 of the holes 21 in the direction parallel to the first surface 7 is larger than the average spacing w2 between the adjacent holes 21. A small coated tool 1 can be produced.

At this time, since the thickness of the intermediate region 19c is as thin as about 50 to 300 nm, the holes 21 formed in the intermediate region 19c are aligned in the direction along the boundary 16 between the first layer 13 and the second layer 15. It is possible to position.

Next, the second region 19b in the first layer 13 is formed. 1 to 4% by volume of titanium tetrachloride gas, 5 to 20% by volume of nitrogen gas, 0.1 to 10% by volume of methane gas, and 0% to 10% by volume of carbon dioxide gas are added to hydrogen gas. By mixing, a fourth mixed gas is produced. A fourth mixed gas is introduced into the chamber at a gas partial pressure of 5 to 45 kPa to form a second region 19b containing HT-titanium carbonitride with a thickness of about 0.3 to 3 μm in a temperature range of 950 to 1050°C. film.

Next, the second layer 15 is deposited. The deposition temperature is set to 1020° C. to 1050° C., the gas pressure is set to 3 kPa to 5 kPa, and the reaction gas composition is hydrogen gas and 1.5% to 10% by volume of aluminum trichloride (AlCl ₃ ) gas. 5% to 5% by volume of hydrogen chloride (HCl) gas, 5% to 15% by volume of carbon dioxide gas, and 0.05% to 1.25% by volume of hydrogen sulfide (H ₂ S) gas are mixed to prepare a fifth mixed gas. A fifth mixed gas is introduced into the chamber to deposit the second layer 15 .

Using such deposition conditions, the second layer 15 having the configuration of the present disclosure can be deposited. In particular, the composition of the fifth mixed gas is hydrogen gas, 1.5% by volume to 2.5% by volume of aluminum trichloride (AlCl ₃ ) gas, and 1.5% by volume to 2.5% by volume of hydrogen chloride. (HCl) gas, 5% to 10% by volume of carbon dioxide gas, and 0.75% to 1.25% by volume of hydrogen sulfide (H ₂ S) gas are mixed to form the second layer 15. The ratio of the Σ3 type grain boundary length to the total length of the Σ3 to Σ29 type grain boundaries at the grain boundaries of α-aluminum oxide crystals can be 60% or more.

After that, if necessary, the portion where the cutting edge 11 is located on the surface of the deposited coating layer 5 is polished. When such a polishing process is performed, welding of the work material to the cutting edge 11 is easily suppressed, so that the coated tool 1 further has excellent chipping resistance.

In addition, said manufacturing method is an example of the method of manufacturing the coated tool 1. FIG. Therefore, it cannot be overemphasized that the covered tool 1 is not limited to what was produced by said manufacturing method. For example, a separate third layer may be deposited on the second layer 15 .

In the cross section perpendicular to the first surface 7, the average value of the width w1 of the holes 21 in the direction parallel to the first surface 7 is the average value of the height h1 of the holes 21 in the direction perpendicular to the first surface 7. In order to manufacture a coated tool 1 larger than the value, it is preferable to adjust the time when forming the intermediate region 19c so that the intermediate region 19c has a thickness of about 50 to 150 nm.

In a cross section orthogonal to the first surface 7, the average value of the distance d1 from the pores 21 to the boundary 16 is larger than the average value of the height h1 of the pores 21 in the direction orthogonal to the first surface 7. 1, the time is adjusted when the intermediate region 19c is formed, and after the film is formed to a thickness of about 50 to 150 nm, the second region 19b in the first layer 13 is formed to a thickness of about 0.5 to 3 μm. It is preferable to form a film with a thickness of

In order to manufacture the coated tool 1 in which the average value of the distance d1 from the hole 21 to the boundary 16 in the cross section orthogonal to the first plane is larger than the average value of the interval w2 between the adjacent holes 21, the first layer It is preferable to form the film so that the second region 19 b in 13 is thicker than the average value of the interval w2 between the adjacent holes 21 .

DESCRIPTION OF SYMBOLS 1... Covered tool 3... Base|substrate 5... Coating layer 7... 1st surface 9... 2nd surface 11... Cutting edge 13... 1st layer 15... 2nd Layer 16 ... Boundary (boundary between the first layer and the second layer)
DESCRIPTION OF SYMBOLS 17... Titanium nitride layer 19... Titanium carbonitride layer 19a... 1st area|region 19b... 2nd area|region 19c... Intermediate area 21... Hole 23... Through hole 101... Cutting tool 103... Pocket 105... Holder 107... Fixing screw

Claims (7)

a substrate having a first surface;
a coating layer overlying at least the first surface of the substrate, comprising:
The coating layer includes a first layer containing a titanium compound located on the first surface and a second layer containing a plurality of α-aluminum oxide crystals located on and in contact with the first layer. and
In the cross section orthogonal to the first surface, the second layer has a grain boundary length that accounts for the sum of the lengths of the Σ3 to Σ29 grain boundaries in the grain boundaries of the α-aluminum oxide crystal, The grain boundary length of the Σ3 type is the maximum,
The first layer includes a first region containing MT-titanium carbonitride, a second region located farther from the substrate than the first region and containing HT-titanium carbonitride, and the first region. and an intermediate region having a thickness of 50 to 300 nm located between and the second region,
The coating layer has, in the intermediate region , a plurality of holes arranged side by side in a direction along the boundary between the first layer and the second layer, and the width of the holes in the direction along the boundary is A coated tool, the average value of which is smaller than the average value of the distances between the adjacent pores. 2. The coated tool according to claim 1, wherein the ratio of the Σ3-type grain boundary length to the total length of the Σ3-Σ29-type grain boundaries is 60% or more. The coated tool according to claim 1 or 2, wherein titanium carbonitride is contained as said titanium compound contained in said first layer. In the cross section orthogonal to the first surface, the average width of the pores in the direction parallel to the first surface is greater than the average height of the pores in the direction orthogonal to the first surface. The coated tool according to any one of claims 1 to 3, which is also large. 2. An average value of distances from the pores to the boundary in a cross section orthogonal to the first surface is larger than an average value of heights of the pores in a direction orthogonal to the first surface. 4. The coated tool according to any one of 1 to 4. 3. In a cross section orthogonal to the first plane, an average value of distances from the holes to the boundary is larger than an average value of distances between adjacent holes in a direction parallel to the first plane. A coated tool according to any one of 1 to 5. a rod-shaped holder extending from a first end toward a second end and having a pocket located on the side of the first end;
A cutting tool comprising a coated tool according to any one of claims 1 to 6 located within said pocket.

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