JP2011005569A - Surface-coated cutting tool with hard coating layer exerting excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool with a hard coating layer exerting excellent chipping resistance in high speed heavy cutting.SOLUTION: The surface-coated cutting tool has (a) a Ti compound layer as a lower layer, (b) an α type AlOlayer as an intermediate layer, and (c) a Y-containing α type AlOlayer, as an upper layer, having a crystal grain structure having a plane polygonal shape and a longitudinally long shape and containing Y, which are vapor-deposited at a surface of a tool base body. The intermediate layer and the upper layer are comprised of the α type AlOlayer with high (0001) plane orientation ratio and the Y-containing α type AlOlayer, respectively. Of the crystal grains in the upper layer, the inside of the crystal grains of ≥60% by an area ratio is divided by a crystal lattice interface comprising a constituent atom sharing lattice point form represented by at least one or more Σ3 s.

Description

  This invention is a high-speed intermittent cutting condition in which cutting of high hardness steel such as hardened material of alloy tool steel and bearing steel, for example, is accompanied by high heat generation and intermittent and impact load repeatedly acts on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance over a long period of use without causing chipping of the hard coating layer.

As shown in Patent Document 1, conventionally, a substrate composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet (hereinafter collectively referred to as a tool). On the surface of the substrate)
(A) a Ti compound layer in which the lower layer is composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, and has an overall average layer thickness of 3 to 20 μm,
(B) The upper layer has an average layer thickness of 1 to 15 μm and has an α-type crystal structure in the state of chemical vapor deposition, and within the measurement range of the surface polished surface using a field emission scanning electron microscope. Each crystal grain having an existing hexagonal crystal lattice is irradiated with an electron beam, and the (0001) plane and the (10-10) plane, which are crystal planes of the crystal grain, with respect to the normal line of the surface polished surface The inclination angle formed by the normal is measured. In this case, the crystal grains have a crystal structure of a corundum type hexagonal close-packed crystal in which constituent atoms composed of Al and oxygen are present at lattice points. Based on the tilt angle, the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated, Share constituent atoms between the constituent atomic shared lattice points There are N lattice points (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but when the upper limit of N is 28 in terms of distribution frequency, 4, 8, 14, 24 In the constituent atomic shared lattice distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 when the existing constituent atomic shared lattice point form is expressed by ΣN + 1, the highest peak is at Σ3. An α-type Al ₂ O ₃ layer (conventional α-type Al ₂ O ₃ layer) showing a constituent atom shared lattice point distribution graph in which the distribution ratio of the Σ3 to the entire ΣN + 1 is 60 to 80%,
A coated tool (referred to as a conventional coated tool 1) formed by vapor-depositing a hard coating layer composed of the above (a) and (b) is known, and this conventional coated tool 1 has an α-type Al ₂ O ₃ layer. Since it has excellent high-temperature strength, it is known to exhibit excellent chipping resistance in high-speed intermittent cutting.

Further, as shown in Patent Document 2, instead of the upper layer (b) of the conventional coated tool 1, an α-type (Al, Y) ₂ O ₃ layer (hereinafter referred to as a conventional AlYO layer) containing a small amount of Y (yttrium). (Hereinafter referred to as the conventional coated tool 2) is also known, and the conventional coated tool 2 prevents the falling of α-type Al ₂ O ₃ crystal grains and is capable of continuous cutting. It is known to show excellent cutting durability in processing.

JP 2006-198735 A JP 2004-1154 A

In recent years, the performance of cutting machines has been dramatically improved, while there is a strong demand for labor saving, energy saving, and cost reduction for cutting, and with this trend, cutting tends to become even faster and more efficient. The conventional coated tools 1 and 2 are not particularly problematic when used for high-speed cutting and high-speed intermittent cutting of general steel such as low alloy steel and carbon steel, and ordinary cast iron such as gray cast iron. However, when this is used for high-speed intermittent cutting of hardened steel such as alloy tool steel and bearing steel, the conventional α-type Al ₂ O ₃ layer and the conventional AlYO layer have high-temperature strength. In addition, since the surface properties are not satisfactory, chipping is likely to occur, and due to this, the service life is reached in a relatively short time.

  In view of the above, the present inventors, when used for high-speed intermittent cutting of high-hardness steel that involves high heat generation and intermittent and impact load acts repeatedly on the cutting edge, from the above viewpoint. In addition, as a result of earnest research to develop a coated tool that has excellent chipping resistance and exhibits excellent cutting performance over a long period of use, the following findings were obtained.

(A) The conventional α-type Al ₂ O ₃ layer in the conventional coated tool 1 is
For example, in a normal chemical vapor deposition system,
Reaction gas composition: by _{volume%, AlCl 3: 6~10%,} CO 2: 10~15%, HCl: 3~5%, H 2 S: 0.05~0.2%, H 2: remainder,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 3 to 5 kPa,
It can be formed under the conditions of
Similarly, using a normal chemical vapor deposition system,
Reaction gas composition:% by volume, AlCl ₃ : 3 to 10%, CO ₂ : 0.5 to 3%, C ₂ H ₄ : 0.01 to 0.3%, H ₂ : remaining,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 3 to 13 kPa,
Under these low temperature conditions, Al ₂ O ₃ nuclei are formed on the surface of the lower Ti compound layer. In this case, the Al ₂ O ₃ nuclei are Al ₂ O ₃ nuclei thin films having an average layer thickness of 20 to 200 nm. Subsequently, the reaction atmosphere is changed to a hydrogen atmosphere at a pressure of 3 to 13 kPa, and the reaction atmosphere temperature is raised to 1100 to 1200 ° C., and the Al ₂ O ₃ core thin film is heated. When an α-type Al ₂ O ₃ layer as a hard coating layer is formed under normal conditions, an α-type Al ₂ O ₃ layer (hereinafter referred to as “reform”) deposited on the heat-treated Al ₂ O ₃ core thin film is obtained. (Referred to as an α-type Al ₂ O ₃ layer), using a field emission scanning electron microscope, as shown in FIGS. Irradiate each individual crystal grain with an electron beam to obtain a normal to the polished surface In contrast, the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle in the range of 0 to 45 degrees out of the measurement inclination angles is 0.25. When it is divided into pitches of degrees and is represented by an inclination angle distribution graph obtained by summing up the frequencies existing in each division, as shown in FIG. 2, a sharp peak at a specific position of the inclination angle division According to the test results, when the reaction atmosphere pressure in the chemical vapor deposition apparatus is changed within the range of 5 to 8 kPa as described above, the position where the sharpest peak appears is 0 to 10 degrees of the inclination angle section. The total of the frequencies that vary within the range and within the range of 0 to 10 degrees occupies a ratio of 45% or more of the total degrees in the tilt angle frequency distribution graph (the (0001) plane orientation ratio is high). The resulting slope of Hot highest peak of the inclination angle segment within the range of 0 to 10 degrees in the frequency distribution graph is modified α type the Al ₂ O ₃ layer which appears, which is superior to conventional α type the Al ₂ O ₃ layer prior coated tool 1 is provided In addition to hardness and heat resistance, it has excellent high temperature strength.

(B) Further, the modified α-type Al ₂ O ₃ layer formed by vapor deposition under the conditions as described in (a) above is used as an intermediate layer, and an upper layer is formed thereon with an α-type crystal structure in the state of chemical vapor deposition. When a hard coating layer is formed by further vapor-depositing a Y-containing aluminum oxide layer, a lower layer made of a Ti compound layer, an intermediate layer made of a modified α-type Al ₂ O ₃ layer, and a Y-containing layer are formed on the tool base surface. The coated tool formed by vapor-depositing the upper layer made of an aluminum oxide layer as a hard coating layer is accompanied by high heat generation, and even under high-speed heavy cutting conditions in which a high cutting depth and high load act on the cutting blade, It has been found that excellent chipping resistance is exhibited by having excellent high-temperature strength and surface properties.

(C) The Y-containing aluminum oxide layer is formed on the modified α-type Al ₂ O ₃ layer, which is an intermediate layer, for example,
First, as the first step,
(B) Reaction gas composition (volume%):
AlCl ₃ : 1 to 5%,
YCl ₃ : 0.05 to 0.1%,
CO ₂ : 2-6%,
HCl: 1-5%,
H ₂ S: 0.25~0.75%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 1020 to 1050 ° C.,
(C) Reaction atmosphere pressure; 3-5 kPa,
After performing the first stage deposition for 1 hour under the conditions of
Next, as the second stage,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
YCl ₃ : 0.4 to 1.0%,
CO _2: 4~8%,
HCl: 3-5%,
H ₂ S: 0.25~0.6%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 920 to 1000 ° C.,
(C) Reaction atmosphere pressure; 6 to 10 kPa,
By carrying out vapor deposition under the conditions, the Y layer has a mean layer thickness of 1 to 15 μm, and the content ratio of the Y component in the total amount with the Al component is 0.0005 to 0.01 (however, the atomic ratio). A satisfactory Y-containing aluminum oxide layer (hereinafter referred to as a modified AlYO layer) having an α-type crystal structure can be formed in the state of chemical vapor deposition.

(D) Then, when the microstructure of the modified AlYO layer is observed with a field emission scanning electron microscope, as shown in FIG. 3 (a), large grains are observed when viewed in a plane perpendicular to the layer thickness direction. As shown in FIG. 3B, when viewed in a plane parallel to the layer thickness direction, the layer surface is almost flat and long in the layer thickness direction. It has a textured structure composed of crystal grains having a shape (hereinafter, referred to as “long flat plate polygonal shape”).
In the vapor deposition formation of the modified AlYO layer, more limited vapor deposition conditions (for example, H ₂ S in the reaction gas in the first stage is 0.50 to 0.75 vol%, and the reaction atmosphere temperature is 1020 to 1030 ° C. And, further, conditions in which YCl ₃ in the reaction gas in the second stage is 0.6 to 0.8% by volume, H ₂ S is 0.25 to 0.4% by volume, and the reaction atmosphere temperature is 960 to 980 ° C. 3), as shown in FIG. 3C, when viewed in a plane perpendicular to the layer thickness direction, it has a flat hexagonal shape with a large grain size and is parallel to the layer thickness direction. When viewed in-plane, as shown in FIG. 3B, the layer surface is substantially flat, and crystal grains having a long shape in the layer thickness direction are in-plane perpendicular to the layer thickness direction. In this case, a tissue structure occupying an area ratio of 35% or more of the whole is formed.

(E) Further, as in the case of the modified α-type Al ₂ O ₃ layer, a hexagonal crystal existing in the measurement range of the surface polished surface of the modified AlYO layer using a field emission scanning electron microscope. By irradiating each crystal grain having a lattice with an electron beam, an inclination angle formed by a normal line of the (0001) plane which is a crystal plane of the crystal grain is measured with respect to a normal line of the surface polished surface, and the measurement Among the inclination angles, the measurement inclination angle within the range of 0 to 45 degrees is divided for each pitch of 0.25 degrees, and an inclination angle number distribution graph is created by counting the frequencies existing in each division. However, a sharp maximum peak appears at a specific position in the tilt angle section, and the total frequency existing in the range of the tilt angle section 0 to 10 degrees accounts for 60% or more of the entire frequency in the tilt angle frequency distribution graph. That is, modified AlY with a high (0001) plane orientation ratio An O layer is formed, and this modified AlYO layer has a higher (0001) plane orientation ratio and a higher high-temperature strength than the conventional AlYO layer of a conventional coated tool.

(F) Further, the modified AlYO layer is irradiated with an electron beam to each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Measure the angle at which each normal of the crystal lattice plane composed of crystal crystal lattice intersects the normal of the substrate surface,
From this measurement result, the crystal orientation relationship between adjacent crystal lattices is calculated, and each of the constituent atoms constituting the crystal lattice interface shares one constituent atom between the crystal lattices (constituent atom shared lattice point). ) And the number of lattice points that do not share constituent atoms between the constituent atomic shared lattice points (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but the distribution frequency) In the case where the upper limit of N is 28 from this point, even numbers of 4, 8, 14, 24 and 26 do not exist)
As shown in FIG. 4, the inside of the above-mentioned crystal grains having an area ratio of 60% or more among the flat polygonal long crystal grains constituting the modified AlYO layer observed with a field emission scanning electron microscope. Indicates a structure separated by at least one crystal lattice interface (hereinafter referred to as Σ3 corresponding interface) having a configuration of shared atomic lattice points represented by Σ3.

(H) As described above, the upper layer composed of the modified AlYO layer has an increased (0001) plane orientation ratio, and the crystal plane of the surface is a crystal plane in a plane perpendicular to the layer thickness direction of the layer (for example, , (0001)), the layer surface is formed in a substantially flat plate shape (when viewed in a plane parallel to the layer thickness direction), and has excellent chipping resistance due to its surface properties. In addition, the presence of the Σ3-compatible interface inside the long, flat plate-shaped crystal grains increases the strength within the crystal grains, so that the high-temperature hardness and high-temperature strength are superior to those of conventional AlYO layers. With excellent chipping resistance.

(I) Therefore, as the hard coating layer, a modified α-type Al ₂ O ₃ layer having a high (0001) plane orientation ratio and excellent high-temperature strength is provided as an intermediate layer, and further excellent high-temperature hardness and high-temperature strength. The coated tool of the present invention, which has a modified AlYO layer having surface properties as an upper layer, has better high-temperature hardness, heat resistance, and high-temperature strength than the conventional coated tools 1 and 2, and as a result. As a result, even when used for high-speed intermittent cutting with high heat generation and intermittent and impact load acting repeatedly on the cutting edge, it exhibits excellent chipping resistance over a long period of use. is there.

This invention has been made based on the above findings,
“(1) On the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) the lower layer is formed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, all formed by chemical vapor deposition; And a Ti compound layer having a total average layer thickness of 3 to 20 μm,
(B) the intermediate layer has an average layer thickness of 1 to 5 μm, and an aluminum oxide layer having an α-type crystal structure in the state of chemical vapor deposition;
(C) The upper layer has an average layer thickness of 2 to 15 μm, and a Y-containing aluminum oxide layer having an α-type crystal structure in a chemical vapor deposited state;
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) to (c) is formed by vapor deposition,
The intermediate layer (b) is irradiated with an electron beam on each crystal grain having a hexagonal crystal lattice existing in the measurement range of the surface polished surface of the tool base using a field emission scanning electron microscope, The inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain is measured with respect to the normal line of the surface polished surface, and the measurement is in the range of 0 to 45 degrees of the measurement inclination angle. When the tilt angle is divided into pitches of 0.25 degrees and the frequency distribution in each section is aggregated, the slope angle distribution graph within the range of 0 to 10 degrees is the highest. An inclination angle number distribution graph in which the total of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph, with the presence of a peak,
The upper layer of (c) has a flat plate shape in a plane perpendicular to the layer thickness direction and a layer thickness direction in a plane parallel to the layer thickness direction when the structure is observed with a field emission scanning electron microscope. It is a Y-containing aluminum oxide layer having a structure composed of crystal grains having a vertically long shape,
Further, with respect to the upper layer of (c), an electron beam is irradiated to each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface of the tool base using a field emission scanning electron microscope. The inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain is measured with respect to the normal line of the surface polished surface, and is within the range of 0 to 45 degrees of the measured inclination angle. When a certain tilt angle is divided into pitches of 0.25 degrees, and the tilt angle distribution graph is formed by summing up the frequencies existing in each section, the tilt angle sections within the range of 0 to 10 degrees An inclination angle number distribution graph in which the highest peak is present and the total frequency within the range of 0 to 10 degrees occupies a ratio of 60% or more of the entire frequency in the inclination angle distribution graph,
Further, the upper layer of the above (c) is irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus, thereby obtaining a hexagonal crystal. Measures the angle at which each normal of the crystal lattice plane consisting of crystal lattices intersects the normal of the substrate surface, and calculates the crystal orientation relationship between adjacent crystal lattices from this measurement result, and configures the crystal lattice interface The distribution of lattice points (constituent atom shared lattice points) in which each atom shares one constituent atom between the crystal lattices is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points are calculated. (However, N is an even number of 2 or more due to the crystal structure of the corundum hexagonal close-packed crystal. However, when the upper limit of N is 28 from the point of distribution frequency, even numbers of 4, 8, 14, 24 and 26 exist. Without) sharing existing constituent atoms When the child dot form is represented by ΣN + 1, the crystal grains having an area ratio of 60% or more among the crystal grains constituting the upper layer of the above (c) are represented by at least one Σ3 It is a Y-containing aluminum oxide layer that is divided by a crystal lattice interface composed of atomic shared lattice points.
A surface-coated cutting tool characterized by that.
(2) When the upper layer of (c) is observed with a field emission scanning electron microscope, a flat hexagonal shape in a plane perpendicular to the layer thickness direction and a layer thickness in a plane parallel to the layer thickness direction The surface-coated cutting tool according to (1), wherein the crystal grains having a long shape in the direction occupy an area ratio of 35% or more of the whole in a plane perpendicular to the layer thickness direction.
(3) The surface-coated cutting tool according to any one of (1) and (2), wherein the upper layer of (c) has a surface roughness (Ra) in a range of 0.05 to 0.3 μm. "
It has the characteristics.

Below, the constituent layer of the hard coating layer of the coated tool of this invention is demonstrated in detail.
(A) Ti compound layer (lower layer)
Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, carbonate (hereinafter referred to as TiCO) layer and carbonitriding The Ti compound layer consisting of one or more of the material layers (hereinafter referred to as TiCNO) is basically present as a lower layer of the modified α-type Al ₂ O ₃ layer, which is an intermediate layer. Contributes to improving the high-temperature strength of the hard coating layer due to its excellent toughness and wear resistance, and firmly adheres to both the tool base and the modified α-type Al ₂ O ₃ layer, so that the tool of the hard coating layer Although it has the effect of contributing to the improvement in adhesion to the substrate, if the total average layer thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exerted, while if the total average layer thickness exceeds 20 μm, the heat is particularly high. Intermittent load acts under occurrence Easily cause chipping in a high-speed intermittent cutting conditions, which since it will cause abnormal wear, defining a total average layer thickness thereof and 3 to 20 [mu] m.

(B) Modified α-type Al ₂ O ₃ layer (intermediate layer)
As described above, the modified α-type Al ₂ O ₃ layer constituting the intermediate layer is
Using normal chemical vapor deposition equipment,
Reaction gas composition:% by volume, AlCl ₃ : 3 to 10%, CO ₂ : 0.5 to 3%, C ₂ H ₄ : 0.01 to 0.3%, H ₂ : remaining,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 3 to 13 kPa,
Under these low temperature conditions, Al ₂ O ₃ nuclei are formed on the surface of the lower Ti compound layer. In this case, the Al ₂ O ₃ nuclei are Al ₂ O ₃ nuclei thin films having an average layer thickness of 20 to 200 nm. Subsequently, the reaction atmosphere is changed to a hydrogen atmosphere at a pressure of 3 to 13 kPa, and the reaction atmosphere temperature is raised to 1100 to 1200 ° C., and the Al ₂ O ₃ core thin film is heated. The α-type Al ₂ O ₃ layer as a hard coating layer can be formed under normal conditions, and the α-type Al ₂ O ₃ layer can be deposited on the heat-treated Al ₂ O ₃ core thin film.
Then, with respect to the modified α-type Al ₂ O ₃ layer chemically vapor-deposited on the lower layer, measurement of the surface polished surface is performed using a field emission scanning electron microscope, as shown in FIGS. Each crystal grain having a hexagonal crystal lattice existing in the range is irradiated with an electron beam, and the normal line of the (0001) plane which is the crystal plane of the crystal grain is formed with respect to the normal line of the surface polished surface. The inclination angle is measured, and among the measurement inclination angles, the measurement inclination angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees, and the frequencies existing in each division are totaled. When represented by the inclination angle number distribution graph, as illustrated in FIG. 2, a sharp maximum peak appears in the range of the inclination angle section 0 to 10 degrees.
And the highest peak position of the measured inclination angle in the inclination angle number distribution graph of the modified α-type Al ₂ O ₃ layer is changed by performing a heat treatment after forming an Al ₂ O ₃ nucleus (thin film) having a predetermined layer thickness. At the same time, an inclination angle number distribution graph is shown in which the total number of frequencies existing in the inclination angle range of 0 to 10 degrees occupies a ratio of 45% or more of the entire frequency in the inclination angle distribution graph ((0001 Therefore, even if the layer thickness of the Al ₂ O ₃ nucleus (thin film) is smaller or larger, the highest peak of the measured tilt angle is obtained. The position deviates from the range of 0 to 10 degrees, and correspondingly, the ratio of the frequencies existing in the range of 0 to 10 degrees in the inclination angle frequency distribution graph is less than 45% of the entire frequencies. , Excellent high It is not possible to ensure the strength.
The modified α-type Al ₂ O ₃ layer has excellent high-temperature strength and heat resistance in addition to the excellent high-temperature hardness and heat resistance of the conventional α-type Al ₂ O ₃ layer of the conventional coated tool. By configuring the Al ₂ O ₃ layer as an intermediate layer having a high (0001) plane orientation ratio, the (0001) plane orientation ratio of the modified AlYO layer deposited on the Al ₂ O ₃ layer can be increased. As a result, it is possible to improve the surface properties of the upper layer made of the modified AlYO layer and improve the high temperature strength.
However, it is impossible to allowed to sufficiently equipped with the properties possessed by the modified α-type Al ₂ O ₃ layer to the hard coating layer has an average layer thickness of the intermediate layer made of the reformed α-type the Al ₂ O ₃ layer is less than 1μm On the other hand, if the average layer thickness exceeds 5 μm, chipping that causes abnormal wear is likely to occur due to high heat generated during cutting and intermittent impact load on the cutting edge, and wear is accelerated. Therefore, the average layer thickness was determined to be 1 to 5 μm.

(C) Modified AlYO layer (upper layer)
In the upper layer composed of the modified AlYO layer chemically vapor-deposited on the intermediate layer, the constituent Al component improves the high-temperature hardness and heat resistance of the layer, and a small amount (with Al) The Y component containing Y / (Al + Y) in the proportion of the total amount of 0.0005 to 0.01 (wherein the atomic ratio) improves the crystal grain interface strength of the modified AlYO layer, Although it contributes to the improvement, if the content ratio of the Y component is less than 0.0005, the above-described effect cannot be expected. On the other hand, if the content ratio of the Y component exceeds 0.01, _{Since the} grain interface strength decreases due to precipitation of ₂ O ₃ particles, the content ratio of the Y component in the total amount with the Al component (value of the ratio of Y / (Al + Y)) is 0.0005 to 0.01 ( However, the atomic ratio is desirable.

The modified AlYO layer can be formed by vapor deposition by adjusting the chemical vapor deposition conditions of the reaction gas composition, the reaction atmosphere temperature, and the reaction atmosphere pressure during the vapor deposition, for example, as follows.
First of all,
(B) Reaction gas composition (volume%):
AlCl ₃ : 1 to 5%,
YCl ₃ : 0.05 to 0.1%,
CO ₂ : 2-6%,
HCl: 1-5%,
H ₂ S: 0.25~0.75%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 1020 to 1050 ° C.,
(C) Reaction atmosphere pressure; 3-5 kPa,
After performing the first stage deposition for about 1 hour under the conditions of
next,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
YCl ₃ : 0.4 to 1.0%,
CO _2: 4~8%,
HCl: 3-5%,
H ₂ S: 0.25~0.6%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 920 to 1000 ° C.,
(C) Reaction atmosphere pressure; 6 to 10 kPa,
When the vapor deposition layer having an average layer thickness of 1 to 15 μm is formed by performing the second stage vapor deposition under the conditions, the value of the ratio Y / (Al + Y) is 0.0005 to 0.01 in atomic ratio. A modified AlYO layer can be formed.

  When the microstructure of the modified AlYO layer is observed with a field emission scanning electron microscope, the crystal grain size is large when viewed in a plane perpendicular to the layer thickness direction as shown in FIG. As shown in FIG. 3B, the surface of the layer is substantially flat when viewed in a plane parallel to the layer thickness direction, as shown in FIG. A texture structure composed of crystal grains having a long shape (flat polygonal long crystal grains) is formed.

As for the modified AlYO layer, as in the case of the modified α-type Al ₂ O ₃ layer constituting the intermediate layer, the inclination angle formed by the normal of the (0001) plane with respect to the normal of the surface polished surface is When an inclination angle distribution graph is created by measuring, a peak exists in the range of 0 to 10 degrees of the inclination angle section, and the total of the frequencies in the range of 0 to 10 degrees is the entire frequency in the inclination angle distribution graph. An inclination angle number distribution graph occupying a ratio of 60% or more of is shown, and it can be seen that the (0001) plane orientation ratio of the modified AlYO layer constituting the upper layer is high.
That is, the modified AlYO layer is formed such that the (0001) plane orientation ratio of the modified α-type Al ₂ O ₃ layer, which is an intermediate layer, is 45% or more. Therefore, the modified AlYO layer is also (0001). It is formed as a layer having a high plane orientation ratio (the (0001) plane orientation ratio is 60% or more).
And when the upper layer is viewed in a plane parallel to the layer thickness direction, the layer surface is formed in a substantially flat plate shape and exhibits excellent surface properties, and as a result, compared to the conventional AlYO layer, Excellent chipping resistance.

Further, in the deposition of the modified AlYO layer, more limited conditions (for example, H ₂ S in the reaction gas in the first stage is 0.50 to 0.75 vol%, the reaction atmosphere temperature is 1020 to 1030 ° C., Further, in the second stage, YCl ₃ in the reaction gas is 0.6 to 0.8% by volume, H ₂ S is 0.25 to 0.4% by volume, and the reaction atmosphere temperature is 960 to 980 ° C. When vapor deposition is performed, as shown in FIG. 3 (c), when viewed in a plane perpendicular to the layer thickness direction, it is a flat hexagonal shape with a large grain size and in a plane parallel to the layer thickness direction. As shown in FIG. 3B, the layer surface is substantially flat, as shown in FIG. 3B, and the crystal grains having a long shape in the layer thickness direction are entirely within a plane perpendicular to the layer thickness direction. A tissue structure occupying an area ratio of 35% or more is formed.

Further, the modified AlYO layer was irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus, and a hexagonal crystal lattice Measure the angle at which each normal of the crystal lattice plane consisting of intersects with the normal of the surface polished surface,
From this measurement result, the crystal orientation relationship between adjacent crystal lattices is calculated, and each of the constituent atoms constituting the crystal lattice interface shares one constituent atom between the crystal lattices (constituent atom shared lattice point). ) And the number of lattice points that do not share constituent atoms between the constituent atomic shared lattice points (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but the distribution frequency) When the upper limit of N is 28 from this point, the even number of 4, 8, 14, 24 and 26 does not exist.)
As shown in FIG. 4, among the flat polygonal long crystal grains constituting the modified AlYO layer observed with a field emission scanning electron microscope, the above flat plate polygons (including flat hexagons) are formed. It can be seen that among the long crystal grains, the interior of the crystal grains having an area ratio of 60% or more is divided by at least one Σ3-compatible interface.
Further, the presence of the above-mentioned Σ3-corresponding interface inside the long polygonal crystal grains (including flat hexagonal) of the modified AlYO layer improves the strength within the grains, and as a result As a result, cracks are prevented from occurring in the modified AlYO layer during high-speed heavy cutting with high loads, and even if cracks occur, crack growth and propagation are hindered, and chipping resistance In addition, chipping resistance and peeling resistance can be improved.

Therefore, a modified AlYO layer having a high (0001) plane orientation ratio and a flat surface property, and having a Σ3-compatible interface inside a long plate crystal polygon (including a flat hexagon) The upper layer of the present invention is accompanied by high heat generation, and does not cause chipping, chipping, peeling, etc. even in high-speed intermittent cutting where an intermittent load is applied to the cutting edge, and uneven wear No chipping or the like occurs, and excellent chipping resistance and wear resistance are exhibited over a long period of time.
However, if the thickness of the upper layer composed of the modified AlYO layer is less than 2 μm, the excellent characteristics of the upper layer cannot be fully exhibited, while if the thickness of the upper layer exceeds 15 μm, uneven wear is not achieved. The average layer thickness of the upper layer is determined to be 2 to 15 μm because the chipping that causes it is likely to occur.

For reference, a conventional AlYO layer (described in the above-mentioned Patent Document 2) is obtained by using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus, and the structure structure of the upper layer crystal grains and the configuration of constituent atomic shared lattice points. As a result of the examination, the structure of the crystal grains has a pyramid-like unevenness as shown in FIGS. 5 (a) and 5 (b), and has a structure composed of polygonal long crystal grains. Therefore, the wear resistance was insufficient as compared with the modified AlYO layer.
In addition, regarding the configuration of the constituent atomic shared lattice points of the crystal grains, the area ratio of the crystal grains in which the Σ3-corresponding interface exists within the concave and convex polygonal long crystal grains constituting the conventional AlYO layer is as low as 40% or less. However, it cannot be said that the strength within the crystal grains has been improved.
Therefore, the conventional coated tool 2 in which the upper layer of the hard coating layer is composed of the conventional AlYO layer is accompanied by high heat generation, and chipping and chipping in high-speed intermittent cutting processing in which intermittent impact is repeatedly applied to the cutting edge. The occurrence of peeling or the like cannot be prevented, and uneven wear or the like also occurs, resulting in poor tool performance.

Further, in the coated tool of the present invention, after the modified AlYO layer of the upper layer is formed, the surface is subjected to polishing treatment with a grindstone or polishing treatment with wet blasting, etc., and the surface roughness of the modified AlYO layer Can be further adjusted. For example, by adjusting the surface roughness of the modified AlYO layer to Ra 0.05 to 0.3 μm, it is possible to suppress the occurrence of welding to the surface-coated tool during cutting.
In addition, surface roughness Ra as used in the field of this invention means the value of arithmetic mean roughness Ra prescribed | regulated by JISB0601 (1994), and the measuring method is not specifically limited.

As described above, the coated tool according to the present invention has a modified α-type Al ₂ O ₃ layer having a high (0001) plane orientation ratio and excellent high-temperature hardness and heat resistance as well as excellent high-temperature strength as an intermediate layer. In addition, by increasing the (0001) plane orientation ratio of the modified AlYO layer constituting the upper layer, it is possible to obtain a flat plate polygon (including a flat hexagonal) vertically long crystal grains having surface flatness. Furthermore, by forming an interface corresponding to Σ3 inside the above crystal grain and strengthening the strength within the crystal grain, it consists of long and narrow polygonal crystal grains. Compared to conventional AlYO layers with few interfaces, it has superior surface properties and high-temperature strength. As a result, it generates high heat, and even in high-speed intermittent cutting with intermittent impact on the cutting edge. Excellent chip resistance with hard coating layer Ing property, fracture resistance, and exhibits excellent abrasion resistance and peel resistance, it is possible to further extend the life of the service life.

It is a schematic diagram illustrating a measurement range of the inclination angle in the case of measuring the (0001) plane crystal grains of the α-type the Al ₂ O ₃ layer constituting the hard coating layer. It is an inclination angle number distribution graph of the (0001) plane of the modified α-type Al ₂ O ₃ layer constituting the intermediate layer of the hard coating layer of the coated tool 1 of the present invention. (A) is a flat plate polygonal shape obtained by observation with a field emission scanning electron microscope in a plane perpendicular to the layer thickness direction of the upper layer composed of the modified AlYO layer of the coated tools 1 to 9 of the present invention. It is a schematic diagram which shows a crystal grain structure | tissue structure, (b) is a layer surface obtained by observation with a field emission type | mold scanning electron microscope in the plane parallel to a layer thickness direction similarly, and a layer is substantially flat. It is a schematic diagram which shows the crystal grain structure which has a long shape in the thickness direction, (c) is a surface perpendicular to the layer thickness direction of the upper layer made of the modified AlYO layer of the present coated tool 10-15 1 is a schematic diagram showing a flat hexagonal crystal grain structure obtained by observation with a field emission scanning electron microscope. In the grain boundary analysis figure in the surface perpendicular to the layer thickness direction, measured using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus, for the upper layer composed of the modified AlYO layer of the coated tools 1 to 9 of the present invention. Yes, a solid line indicates a flat-plate polygonal crystal grain boundary observed with a field emission scanning electron microscope, and a broken line indicates a Σ3-corresponding interface in the crystal grain measured by an electron backscatter diffraction image apparatus. (A) is a polygonal crystal grain structure obtained by observation with a field emission scanning electron microscope in a plane perpendicular to the layer thickness direction of the upper layer made of the conventional AlYO layer of the comparative coated tools 1 to 15. It is a schematic diagram which shows a structure, (b) has a pyramid-shaped unevenness | corrugation in the layer surface similarly obtained by observation with the field emission type | mold scanning electron microscope in the surface parallel to a layer thickness direction, It is a schematic diagram which shows the crystal grain structure structure which has a long shape in the thickness direction.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 2 to 4 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By processing, tool bases A to E made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG120408MA were produced.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to e made of TiCN base cermet having a standard / CNMG120408MA chip shape were formed.

Then, each of these tool bases A to E and tool bases a to e is charged into a normal chemical vapor deposition apparatus,
(A) First, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in JP-A-6-8010, and the other conditions are ordinary granularity. Under the conditions shown in Table 7), the Ti compound layer having the target layer thickness shown in Table 7 is deposited as the lower layer of the hard coating layer.
(B) Next, under the conditions shown in Table 4, the modified α-type Al ₂ O ₃ layer having the target layer thickness shown in Table 8 is formed by vapor deposition as an intermediate layer of the hard coating layer.
(C) Next, according to the vapor deposition conditions shown in Table 5, the coated tools 1 to 15 of the present invention are formed by vapor-depositing the modified AlYO layer having the target layer thickness shown in Table 8 as the upper layer of the hard coating layer. Each was manufactured.

In addition, for comparison purposes, the lower layer of the hard coating layer is formed under the conditions shown in Table 3, and the upper layer is formed under the conditions shown in Table 6 (corresponding to the conventional AlYO layer deposition conditions disclosed in Patent Document 2). ) To produce comparative coated tools 1 to 10 (corresponding to conventional coated tool 2) provided with a hard coating layer composed of a Ti compound layer having a target layer thickness shown in Table 9 and a conventional AlYO layer, respectively. .
The tool base type, the lower layer type, and the lower layer thickness of the comparative coated tools 1 to 10 are the same as those of the inventive coated tools 1 to 10, respectively.

Further, for reference, the lower layer of the hard coating layer is formed under the conditions shown in Table 3, and the α-type Al ₂ O ₃ layer is formed under the conditions shown in Table 6 (the conventional α-type disclosed in Patent Document 1). by forming at Al ₂ corresponds to the deposition conditions of the O ₃ layer), reference coated tool having a hard coating layer comprising a target layer Ti compound layer having a thickness in the conventional α-type Al ₂ O ₃ layer as shown in Table 9 11-15 (equivalent to the conventional coated tool 1) were manufactured, respectively.
The tool base type, the lower layer type, and the lower layer thickness of the reference coated tools 11 to 15 are the same as those of the coated tools 11 to 15 of the present invention, respectively.

Further, the surface of some modified AlYO layers of the coated tool of the present invention and the conventional AlYO layers of some of the comparative coated tools are wetted with Al ₂ O ₃ particles having a projection pressure of 0.15 MPa and 200 mesh. A post-treatment consisting of a blast treatment was applied. Note that the post-processing may be a polishing process using an elastic grindstone.
Tables 8 and 9 show the modified AlYO layer of the present invention coated tool subjected to post-treatment (indicated by * in Table 8), the conventional AlYO layer of the comparative coated tool (in Table 9, The value of the surface roughness (Ra (μm)) of those marked with * is shown.
(For reference, the Ra values for the inventive coated tool and comparative coated tool that have not been post-processed are also shown in Tables 8 and 9.)

Subsequently, the modified α-type Al ₂ O ₃ layer constituting the intermediate layer of the hard coating layer of the present invention coated tools 1 to 15, the modified AlYO layer constituting the upper layer, and the comparative coated tools 1 to 10 With respect to the conventional AlYO layer and the conventional α-type Al ₂ O ₃ layers of the reference coating tools 11 to 15, gradient angle distribution graphs were respectively prepared using a field emission scanning electron microscope.
That is, the gradient angle number distribution graph shows the field emission with the respective surfaces of the present invention coated tools 1 to 15, the comparative coated tools 1 to 10, and the reference coated tools 11 to 15 being polished surfaces. A hexagon that is set in a lens barrel of a scanning electron microscope and exists in the measurement range of each surface polished surface with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees and an irradiation current of 1 nA on the polished surface Each crystal grain having a crystal lattice is irradiated, and an electron backscatter diffraction image apparatus is used, and the crystal grain is 30 × 50 μm at a spacing of 0.1 μm / step with respect to the normal of the polished surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and based on this measurement result, the measured tilt angle within the range of 0 to 45 degrees of the measured tilt angle is 0.25. As well as dividing each pitch By aggregating the frequencies present in each segment was created inclination angle frequency distribution graph.
As an example of the inclination angle number distribution graph, the inclination angle number distribution graph of the (0001) plane prepared for the modified α-type Al ₂ O ₃ layer constituting the intermediate layer of the hard coating layer of the coated tool 1 of the present invention is shown in FIG. Indicates.
The “surface” in the present invention includes not only a surface parallel to the substrate surface but also a surface inclined with respect to the substrate surface, for example, a cut surface of a layer.

As a result, the modified α-type Al ₂ O ₃ layer, the modified AlYO layer of the inventive coated tool, the conventional AlYO layer of the comparative coated tools 1 to 10, and the conventional α-type Al ₂ of the reference coated tools 11 to 15 are obtained. In the inclination angle number distribution graph of the O ₃ layer, as shown in Table 8 and Table 9, respectively, the modified α-type Al ₂ O ₃ layer and the modified AlYO layer of the coated tool of the present invention are measured in the (0001) plane. While the angle distribution shows an inclination angle number distribution graph in which the highest peak appears in each inclination angle range within the range of 0 to 10 degrees, the conventional AlYO layer of the comparative coating tools 1 to 10 and the reference coating tools 11 to 11 Fifteen conventional α-type Al ₂ O ₃ layers show an inclination angle number distribution graph in which the distribution of measured inclination angles on the (0001) plane is unbiased within the range of 0 to 45 degrees and there is no highest peak. It was.
Tables 8 and 9 show the ratio of the frequency existing in the tilt angle section within the range of 0 to 10 degrees to the entire tilt angle number distribution graph.

Next, with respect to the modified AlYO layer constituting the upper layer of the inventive coated tools 1 to 15 and the conventional AlYO layer of the comparative coated tools 1 to 10, using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Then, the grain structure and the constituent atomic shared lattice point morphology were investigated.
That is, first, the modified AlYO layer of the present invention-coated tools 1 to 15 and the conventional AlYO layer of the comparative coating tools 1 to 10 were observed using a field emission scanning electron microscope. 15, a large-grained crystal grain structure of a flat plate polygon (including a flat hexagon) and a long shape typically shown in FIGS. 3A and 3B was observed (note that 3A is a schematic diagram of the structure of the coated tools 1 to 9 of the present invention viewed in a plane perpendicular to the layer thickness direction, and FIG. 3C is a diagram viewed in a plane perpendicular to the layer thickness direction. The structure structure schematic diagram which consists of a crystal grain of a flat hexagonal shape and long shape of a large grain size of the present invention coated tools 10-15).
On the other hand, in the comparative coated tools 1 to 10, a polygonal and long crystal grain structure was observed as representatively shown in FIGS. 5 (a) and 5 (b). The diameter was smaller than that of the present invention, and as is clear from FIG. 5B, pyramidal irregularities were formed on the surface of the layer (note that FIGS. 5A and 5B). ) Is a schematic diagram of the structure of comparative coated tools 1 to 15).

Next, with respect to the modified AlYO layer of the present invention coated tools 1 to 15 and the conventional AlYO layer of the comparative coated tools 1 to 10, the crystal grains having a Σ3-compatible interface exist inside the crystal grains constituting the respective layers. The area ratio was measured.
First, the modified AlYO layers of the above-described coated tools 1 to 15 of the present invention are set in a lens barrel of a field emission scanning electron microscope in a state where the surface is a polished surface, and the surface polished surface is set to 70 degrees. Electron backscattering is performed by irradiating an electron beam with an electron beam with an acceleration voltage of 15 kV at an incident angle with an irradiation current of 1 nA on each crystal grain having a hexagonal crystal lattice existing within the measurement range of each surface polished surface. Using a diffractive image apparatus, a 30 × 50 μm region is measured at an interval of 0.1 μm / step, and the angle at which each normal line of each crystal lattice plane of the crystal grain intersects the normal line on the substrate surface is measured. From the crystal orientation relationship between adjacent crystal lattices, the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms constituting the crystal lattice interface shares one constituent atom between the crystal lattices is calculated. Calculate the previous N lattice points that do not share constituent atoms between constituent atomic shared lattice points (however, N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but the upper limit of N is 28 in terms of distribution frequency) In this case, the even number of 4, 8, 14, 24 and 26 does not exist.) When the constituent atomic shared lattice point form which is present is represented by ΣN + 1, all the crystal grains existing within the measurement range of the modified AlYO layer Among these, the area ratio of the crystal grains in which at least one Σ3-corresponding interface exists inside the crystal grains was determined, and the value is shown in Table 8 as the Σ3-compatible interface ratio (%).
Next, with respect to the conventional AlYO layers of the comparative coated tools 1 to 10, among the whole crystal grains existing within the measurement range of the conventional AlYO layer, by the same method as in the coated tool of the present invention, The area ratio of crystal grains in which at least one Σ3-compatible interface exists was determined, and the value is shown in Table 9 as the Σ3-compatible interface ratio (%).

  As shown in Tables 8 and 9, in the modified AlYO layers of the coated tools 1 to 15 of the present invention, the area ratio of the crystal grains in which at least one Σ3 corresponding interface exists in the crystal grains is 60% or more. On the other hand, in the conventional AlYO layers of the comparative coated tools 1 to 10, the area ratio of the crystal grains in which at least one Σ3 corresponding interface exists in the crystal grains is 40% or less, and the inside of the crystal grains It can be seen that the rate at which Σ3 corresponding interfaces exist is very small.

In addition, the modified AlYO layer of the present coated tool 1-15 and the conventional AlYO layer of the comparative coated tool 1-10 are present in a plane perpendicular to the layer thickness direction using a field emission scanning electron microscope. The area ratio of flat hexagonal crystal grains with a grain size was determined. These values are shown in Tables 8 and 9.
In addition, the crystal grains of the “large hexagonal flat hexagonal shape” mentioned here are:
“The diameter of particles existing in a plane perpendicular to the layer thickness direction observed by a field emission scanning electron microscope is measured, the average value of 10 particles is 3 to 8 μm, and the vertex angle is 100 to 140 °. It is a polygonal shape with six apex angles. "
It is defined as

  Next, the thickness of each constituent layer of the hard coating layer of the present coated tool 1-15, comparative coated tool 1-10, and reference coated tool 11-15 was measured using a scanning electron microscope (longitudinal section measurement). However, in any case, the average layer thickness (average value of five-point measurement) substantially the same as the target layer thickness was shown.

Next, for the above-described inventive coated tools 1-15, comparative coated tools 1-10, and reference coated tools 11-15, all are screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SUJ2 (HRC62) lengthwise equidistant four round grooved round bars,
Cutting speed: 250 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed intermittent cutting test of bearing steel under the conditions (cutting condition A) (normal cutting speed is 200 m / min.),
Work material: JIS · SKD11 (HRC58) lengthwise equidistant four round grooved round bars,
Cutting speed: 300 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed intermittent cutting test of alloy tool steel under the conditions (cutting condition B) (normal cutting speed is 200 m / min.),
Work material: JIS · SK3 (HRC61) lengthwise equidistant four round grooved round bars,
Cutting speed: 250 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 150 m / min.) Of carbon tool steel under the following conditions (referred to as cutting conditions C),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 10.

From the results shown in Tables 8 to 10, the present coated tools 1 to 15 have a high ratio in which the (0001) plane orientation ratio of the modified α-type Al ₂ O ₃ layer which is an intermediate layer of the hard coating layer is 45% or more. In addition to having excellent high-temperature strength, the modified AlYO layer constituting the upper layer has a textured structure of flat polygonal (flat hexagonal) and long crystal grains (0001) The plane orientation ratio shows a high ratio of 60% or more, and the area ratio of the crystal grains in which at least one Σ3-compatible interface exists in the crystal grains is as high as 60% or more, or further As a result, the modified AlYO layer has excellent high-temperature strength and in-grain strength, and has improved surface flatness. As a result of having combined, with high heat generation, and In high-speed intermittent cutting where impact loads are intermittently applied to the blade, the hard coating layer exhibits even better chipping resistance, shows excellent cutting performance over a long period of use, and further improves the service life Life extension is possible.
On the other hand, the comparative coating tools 1 to 10 in which the hard coating layer is composed of a Ti compound layer and a conventional AlYO layer, and the reference coating tools 11 to 11 in which the hard coating layer is composed of a Ti compound layer and a conventional α-type Al ₂ O ₃ layer. In No. 15, it is apparent that the service life is reached in a relatively short time due to the occurrence of chipping, acceleration of wear, and the like.

  As described above, the coated tool according to the present invention is not only for cutting under normal conditions such as various steels and cast iron, but also for high-speed intermittent operation in which high heat generation is generated and an impact load is intermittently applied to the cutting blade. Even in the cutting process, the occurrence of chipping can be suppressed, and excellent cutting performance can be demonstrated over a long period of time. It can respond satisfactorily.

Claims (3)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) the lower layer is formed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, all formed by chemical vapor deposition; And a Ti compound layer having a total average layer thickness of 3 to 20 μm,
(B) the intermediate layer has an average layer thickness of 1 to 5 μm, and an aluminum oxide layer having an α-type crystal structure in the state of chemical vapor deposition;
(C) The upper layer has an average layer thickness of 2 to 15 μm, and a Y-containing aluminum oxide layer having an α-type crystal structure in a chemical vapor deposited state;
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) to (c) is formed by vapor deposition,
The intermediate layer (b) is irradiated with an electron beam on each crystal grain having a hexagonal crystal lattice existing in the measurement range of the surface polished surface of the tool base using a field emission scanning electron microscope, The inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain is measured with respect to the normal line of the surface polished surface, and the measurement is in the range of 0 to 45 degrees of the measurement inclination angle. When the tilt angle is divided into pitches of 0.25 degrees and the frequency distribution in each section is aggregated, the slope angle distribution graph within the range of 0 to 10 degrees is the highest. An inclination angle number distribution graph in which the total of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph, with the presence of a peak,
The upper layer of (c) has a flat plate shape in a plane perpendicular to the layer thickness direction and a layer thickness direction in a plane parallel to the layer thickness direction when the structure is observed with a field emission scanning electron microscope. It is a Y-containing aluminum oxide layer having a structure composed of crystal grains having a vertically long shape,
Further, with respect to the upper layer of (c), an electron beam is irradiated to each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface of the tool base using a field emission scanning electron microscope. The inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain is measured with respect to the normal line of the surface polished surface, and is within the range of 0 to 45 degrees of the measured inclination angle. When a certain tilt angle is divided into pitches of 0.25 degrees, and the tilt angle distribution graph is formed by summing up the frequencies existing in each section, the tilt angle sections within the range of 0 to 10 degrees An inclination angle number distribution graph in which the highest peak is present and the total frequency within the range of 0 to 10 degrees occupies a ratio of 60% or more of the entire frequency in the inclination angle distribution graph,
Further, the upper layer of the above (c) is irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus, thereby obtaining a hexagonal crystal. Measures the angle at which each normal of the crystal lattice plane consisting of crystal lattices intersects the normal of the substrate surface, and calculates the crystal orientation relationship between adjacent crystal lattices from this measurement result, and configures the crystal lattice interface The distribution of lattice points (constituent atom shared lattice points) in which each atom shares one constituent atom between the crystal lattices is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points are calculated. (However, N is an even number of 2 or more due to the crystal structure of the corundum hexagonal close-packed crystal. However, when the upper limit of N is 28 from the point of distribution frequency, even numbers of 4, 8, 14, 24 and 26 exist. Without) sharing existing constituent atoms When the child dot form is represented by ΣN + 1, the crystal grains having an area ratio of 60% or more among the crystal grains constituting the upper layer of the above (c) are represented by at least one Σ3 It is a Y-containing aluminum oxide layer that is divided by a crystal lattice interface composed of atomic shared lattice points.
A surface-coated cutting tool characterized by that.   When the upper layer of (c) was observed with a field emission scanning electron microscope, it was flat hexagonal in a plane perpendicular to the layer thickness direction, and in the layer thickness direction in a plane parallel to the layer thickness direction. The surface-coated cutting tool according to claim 1, wherein the crystal grains having a long shape occupy an area ratio of 35% or more of the whole in a plane perpendicular to the layer thickness direction.   The surface-coated cutting tool according to claim 1, wherein the upper layer of (c) has a surface roughness (Ra) in a range of 0.05 to 0.3 μm.

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