JP5440268B2 - Surface coated cutting tool with excellent chipping resistance due to hard coating layer - Google Patents

Description

  The present invention provides a hard coating layer even when cutting of various materials such as steel and cast iron is performed under intermittent heavy cutting conditions in which intermittent and impactful high loads are repeatedly applied to the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance over a long period of use without causing chipping.

Conventionally, as shown in Patent Document 1, 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) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, all formed by chemical vapor deposition as the lower layer A Ti compound layer comprising one or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 3 to 20 μm ,
(B) As an upper layer, it has an average layer thickness of 2 to 20 μm, and an α-type crystal structure in the state of chemical vapor deposition,
Using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and each crystal plane of the crystal grain is The angle at which each of the normals intersects the normal of the substrate surface was measured, and from this measurement result, the (0001) plane and {10-10} plane, which are the constituent crystal planes of the crystal grains, were selected and further selected ( In the (0001) plane and {10-10} plane, the angles at which the normal lines of the (0001) plane and the normal lines of the {10-10} plane intersect each other at the interface between adjacent crystal grains (grain unit). When obtained, the angle at which the normals of the (0001) planes and the normals of the {10-10} planes intersect is 15 degrees or less, and the proportion of the crystal grain interface units is 45% or more of the total crystal grain interface units. Occupied grain interface Reforming the Al ₂ O ₃ layer showing a
A coated tool (hereinafter referred to as a conventional coated tool 1) formed by vapor-depositing a hard coating layer composed of (a) and (b) above is known, and a modified Al ₂ O ₃ layer of the hard coating layer is known. It is known that the hard coating layer exhibits excellent chipping resistance in high-speed cutting because it has excellent crystal grain interface strength.

Further, as shown in Patent Document 2, on the surface of the tool base,
(A) a Ti compound layer in which the lower layer 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 a state of chemical vapor deposition;
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angles formed by the normal lines of the (0001) plane and the (10-10) plane, which are crystal planes of the above, are measured. In this case, the crystal grains are corundum type in which constituent atoms composed of Al and oxygen are present at lattice points. Based on the measured tilt angle obtained as a result of the hexagonal close-packed crystal structure, each of the constituent atoms forms one constituent atom between the crystal grains at the interface between adjacent crystal grains. The distribution of shared lattice points (constituent atom shared lattice points) is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is the crystal structure of the corundum hexagonal close-packed crystal) Even number of 2 or more, but distribution frequency When the upper limit of N from the point is 28, the even number of 4, 8, 14, 24, and 26 does not exist.) When the existing constituent atom shared lattice point form is expressed as ΣN + 1, each ΣN + 1 is included in the entire ΣN + 1 In the constituent atom shared lattice point distribution graph showing the distribution ratio, Al ₂ shows a constituent atom shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio in the entire ΣN + 1 of Σ3 is 60 to 80%. O ₃ layer,
A coated tool (hereinafter referred to as a conventional coated tool 2) formed by vapor-depositing a hard coating layer composed of (a) and (b) is known, and has excellent resistance to high-speed intermittent cutting of steel or cast iron. It is known to exhibit chipping properties.

JP 2007-160497 A JP 2006-198735 A

  In recent years, the performance of cutting equipment has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and along with this, cutting tends to become more efficient. In the conventional coated tools 1 and 2, there is no problem when this is used for high-speed cutting and high-speed interrupted cutting of ordinary steel such as low alloy steel and carbon steel, and ordinary cast iron such as gray cast iron. When this is used for intermittent heavy cutting, the high-temperature strength and surface properties are not satisfactory, so chipping is applied to the cutting edge due to intermittent and impactful high loads that repeatedly act on the cutting edge. In addition, the wear resistance is lowered due to the occurrence of thermoplastic deformation and uneven wear, and these are the causes, and the service life is reached in a relatively short time.

  Therefore, the present inventors have studied the hard coating layer that exhibits excellent wear resistance over a long period of use while improving the chipping resistance from the above-mentioned viewpoints. Obtained knowledge.

(A) The modified Al ₂ O ₃ layer in the conventional coated tool 1 is obtained by increasing the small-angle grain boundary ratio to 45% or more (Patent Document 1), and the Al ₂ O ₃ layer in the conventional coated tool 2 is By increasing the Σ3 ratio to 60% or more (Patent Document 2), the grain boundary strength is improved and chipping resistance is improved, but intermittent and impactful high loads are applied to the cutting edge. When used under severe cutting conditions such as intermittent heavy cutting that repeatedly acts, the Al ₂ O ₃ layer does not have a sufficiently satisfactory high-temperature strength. It could not be said that the effect was sufficient.

(B) Therefore, in the present invention, the modified α-type Al ₂ O ₃ layer formed by vapor deposition under the conditions of the above-mentioned conventional coated tool 1 is used as an intermediate layer, and as an upper layer on the α layer in the state of chemical vapor deposition. A B-containing aluminum oxide layer having a type crystal structure was further formed by vapor deposition to form a hard coating layer. On the surface of the tool base, a lower layer composed of a Ti compound layer and an intermediate composed of a modified α-type Al ₂ O ₃ layer The coated tool formed by vapor-depositing the upper layer consisting of the layer and the B-containing aluminum oxide layer as a hard coating layer is even better under intermittent heavy cutting conditions in which intermittent and impactful high loads act repeatedly on the cutting edge. It has been found that since it has high temperature strength and surface properties, it exhibits excellent chipping resistance and wear resistance.

(C) The B-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 : 6 to 10%,
BCl ₄ : 0 to 0.01%,
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,
After performing the first stage deposition for about 30 minutes under the conditions of
Next, as the second stage,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
BCl ₄ : 0.02 to 0.2%,
CO _2: 4~8%,
HCl: 3-5%,
H ₂ S: 0.25~0.6%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 960-1010 ° C.,
(C) Reaction atmosphere pressure; 6 to 10 kPa,
When the deposition is performed under the conditions, an average layer thickness of 1 to 15 μm, and the content ratio of B component in the total amount of Al component and oxygen component (B / (Al + B + oxygen)) is 0.001. It is possible to form a B-containing aluminum oxide layer (hereinafter referred to as a modified AlBO layer) having an .alpha.-type crystal structure in a state where the chemical vapor deposition is satisfied.

(D) Then, when the microstructure of the modified AlBO layer is observed with a field emission scanning electron microscope, as shown in FIG. 1 (a), large grains are observed when viewed in a plane perpendicular to the layer thickness direction. As shown in FIG. 1B, 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”).
Further, in the vapor deposition formation of the modified AlBO layer, more limited vapor deposition conditions (for example, 0.45 to 0.6% by volume of H ₂ S in the reaction gas in the first stage and a reaction atmosphere temperature of 980 to 1000 ° C. And BCl ₄ in the reaction gas in the second stage is 0.1 to 0.2% by volume, H ₂ S is 0.25 to 0.4% by volume, and the reaction atmosphere temperature is 960 to 980 ° C. 1), as shown in FIG. 1C, 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. 1B, 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, the modified AlBO 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. 2, at least one of the above-mentioned crystal grains having an area ratio of 60% or more among the flat plate-shaped long crystal grains constituting the modified AlBO layer is represented by Σ3. It shows a structure divided by a crystal lattice interface (hereinafter, referred to as a Σ3-corresponding interface) having a configuration of the constituent atomic shared lattice points.
Further, for the modified AlBO layer, an electron beam is individually applied to each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Irradiation is performed to measure the angle at which each normal line of each crystal plane of the crystal grain intersects the normal line of the substrate surface. From this measurement result, the (0001) plane and {10-10] which are the constituent crystal planes of the crystal grain } Planes, and in the selected (0001) plane and {10-10} plane, the normal lines of the (0001) plane at the interface between adjacent crystal grains (grain interface unit) and {10-10 } The angle at which the normals of the plane intersect is obtained, and the crystal grain interface unit in which the angle between the normals of the (0001) plane and the normals of the {10-10} plane intersects is 15 degrees or less. Occupy When the ratio (hereinafter referred to as the ratio of crystal grain interface units having an intersection angle of 15 degrees or less) was calculated, the angle at which the normal lines of the (0001) planes intersect with the normal lines of the {10-10} plane was 15 degrees or less. It has been observed that the crystal grain interface units exhibit a crystal grain interface arrangement that is a proportion of 35% or more of the total crystal grain interface units.

(F) The upper layer composed of the modified AlBO layer formed by vapor deposition under the first and second chemical vapor deposition conditions (hereinafter referred to as the present invention conditions) of (d) above has a crystal plane on the surface, Since it has the same orientation as a crystal plane (for example, (0001)) in a plane perpendicular to the layer thickness direction, the layer surface is almost flat (when viewed in a plane parallel to the layer thickness direction). In addition, it exhibits excellent chipping resistance due to its surface properties, and furthermore, the presence of the Σ3 corresponding interface inside the plate-shaped polygonal long crystal grains enhances the intra-grain strength, so that the conventional (for example, (Disclosed in Patent Document 2) Compared to the aluminum oxide layer, it has excellent high-temperature hardness, high-temperature strength and chipping resistance.

Therefore, a modified α-type Al ₂ O ₃ layer having excellent crystal grain interface strength is provided as an intermediate layer as a hard coating layer, and a modified AlBO layer having excellent high-temperature hardness, high-temperature strength, and surface properties is further provided. The coated tool of the present invention provided as the upper layer has higher high-temperature hardness, heat resistance, and high-temperature strength than conventional coated tools, and as a result, is intermittent and impactful to the cutting edge. Even in intermittent heavy cutting where high loads act repeatedly, excellent wear resistance is exhibited over a long period of time without causing chipping, chipping or peeling.
The research results (a) to (f) have been obtained.

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) a modified aluminum oxide layer having an average layer thickness of 1 to 5 μm and having an α-type crystal structure in the state of chemical vapor deposition;
(C) a B-containing aluminum oxide layer having an average layer thickness of 1 to 15 μm and having an α-type crystal structure in the state of chemical vapor deposition;
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 a hexagonal crystal lattice formed by using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus to irradiate each crystal grain existing within the measurement range of the surface polished surface with an electron beam. The angle at which each normal line of each crystal plane of the crystal grain has a normal line on the substrate surface is measured, and from this measurement result, the (0001) plane and {10-10} which are the constituent crystal planes of the crystal grain In addition, in the selected (0001) plane and {10-10} plane, the normal lines of the (0001) plane at the interface between adjacent crystal grains (grain interface unit) and {10-10} When the angle at which the surface normals intersect is determined, the crystal grain interface unit in which the angle between the normals of the (0001) surface and the normals of the {10-10} surface intersects each other is 15 degrees or less. Over 45% of interface units A modified aluminum oxide layer showing a crystal grain interface sequences occupying,
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 B-containing aluminum oxide layer having a structure composed of crystal grains having a vertically long shape,
Further, the upper layer has a hexagonal crystal lattice by irradiating individual crystal grains existing within the measurement range of the surface polished surface with a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Measure the angle at which each normal of each crystal plane of the crystal grain intersects the normal of the substrate surface, and from this measurement result, calculate the crystal orientation relationship between adjacent crystal lattices, and configure 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) the existing constituent atoms When representing the lattice points form in .SIGMA.N + 1,
Among the crystal grains constituting the upper layer, the interior of the crystal grains having an area ratio of 60% or more is divided by at least one crystal lattice interface composed of a constituent atomic shared lattice point represented by Σ3. B-containing aluminum oxide layer
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 upper layer of (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. The angle at which each normal line of each crystal face of the crystal grain having a crystal lattice intersects the normal line on the substrate surface is measured, and from this measurement result, the (0001) face and {10 -10} planes are selected, and in the selected (0001) planes and {10-10} planes, the normals of the (0001) planes at the interfaces between adjacent crystal grains (grain interface units) and {10 When the angle at which the normals of the −10} plane intersect is determined, the crystal grain interface unit in which the angle between the normals of the (0001) plane and the normals of the {10−10} plane intersects 15 degrees or less. 35% or more of all grain interface units The surface-coated cutting tool according to the above (1) or (2), which is a B-containing aluminum oxide layer showing a crystal grain interface arrangement that occupies the above proportion. "
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. In addition to contributing to improving the high-temperature strength of the hard coating layer due to its excellent high-temperature strength, it firmly adheres to both the tool substrate and the modified α-type Al ₂ O ₃ layer, so that the hard coating layer adheres to the tool substrate. However, if the total average layer thickness is less than 3 μm, the above-mentioned effect cannot be fully exerted. On the other hand, if the total average layer thickness exceeds 20 μm, it is particularly intermittent / impact. High load repeatedly In connection heavy cutting conditions easily cause thermal plastic deformation, which is because the cause of the uneven 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, in the crystal grain interface arrangement, the angle between the normal lines of the (0001) planes and the normal lines of the {10-10} planes at the interface between adjacent crystal grains (crystal grain interface unit) is 15 degrees. When the following crystal grain interface units occupy a ratio of 45% or more of the total crystal grain interface units, the crystal grain interface strength is further improved, and the excellent high-temperature hardness of α-type Al ₂ O ₃ itself and In addition to heat resistance, it has even higher temperature strength.
Therefore, when the ratio of the crystal grain interface units whose normals cross each other is less than 15 degrees is less than 45%, the desired excellent crystal grain interface strength cannot be ensured.
If the average layer thickness is less than 1 μm, the hard coating layer cannot be sufficiently provided with the above characteristics. On the other hand, if the average layer thickness exceeds 5 μm, chipping is caused by intermittent and impactful high loads. Therefore, the average layer thickness was determined to be 1 to 5 μm.

(C) Modified AlBO layer (upper layer)
In the upper layer composed of the modified AlBO 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 trace amount (Al and oxygen The B component containing 0.001 to 0.01 (provided that the atomic ratio) of B / (Al + B + oxygen) is a proportion of the total amount of the improved and improves the crystal grain interface strength of the modified AlBO layer, Although it contributes to the improvement of the high temperature strength, if the content ratio of the B component is less than 0.001, not only the ratio of dividing the crystal grains in the upper layer at the Σ3 crystal lattice interface will be 60% or more, but also the small angle grain boundary ratio On the other hand, when the content ratio of the B component exceeds 0.01, a compound such as B oxide or B acid chloride is formed in the layer, so that Σ3 The ratio of splitting at the crystal lattice interface does not exceed 60%, and Since the grain boundary ratio is also less than 35%, the content ratio of the B component in the total amount of the Al component and oxygen (the value of the ratio of B / (Al + B + oxygen)) is 0.001 to 0.01 (however, an atom Ratio).

The modified AlBO layer can be deposited 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.
That is, first,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
BCl ₄ : 0 to 0.01%,
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,
After performing the first stage deposition for about 30 minutes under the conditions of
next,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
BCl ₄ : 0.02 to 0.2%,
CO _2: 4~8%,
HCl: 3-5%,
H ₂ S: 0.25~0.6%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 960 to 1010 ° 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 ratio value of B / (Al + B + oxygen) is 0.001 to 0.01 in atomic ratio. A modified AlBO layer can be formed.

  When the microstructure of the modified AlBO layer is observed with a field emission scanning electron microscope, as shown in FIG. 1A, the crystal grain size is large when viewed in a plane perpendicular to the layer thickness direction. As shown in FIG. 1B, 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 plate-shaped long crystal grains) is formed, and chipping resistance is further improved.

In the deposition of the modified AlBO layer, more limited conditions (for example, H ₂ S in the reaction gas in the first stage is 0.45 to 0.6% by volume, the reaction atmosphere temperature is 980 to 1000 ° C., Furthermore, the BCl ₄ in the reaction gas in the second stage is 0.1 to 0.2% 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. 1 (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. 1B, the layer surface is substantially flat as shown in FIG. 1 (b), 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 AlBO layer was 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, and from the hexagonal crystal lattice. Measuring the angle at which each normal of the crystal lattice plane intersects 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. 2, at least one of the above-described flat plate polygons (including flat hexagonal) long crystal grains constituting the modified AlBO layer has an area ratio of 60% or more. It turns out that it is divided by the above Σ3 interface.
Further, the presence of the above-mentioned Σ3-corresponding interface inside the long polygonal crystal grains (including flat hexagonal) of the modified AlBO layer improves the strength within the grains, and as a result As described above, the generation of cracks in the modified AlBO layer during intermittent heavy cutting is suppressed, and even if cracks occur, the growth and propagation of cracks is hindered, and chipping resistance, chipping resistance, The peelability is improved.

  Further, for the modified AlBO layer, an electron beam is individually applied to each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Irradiation is performed to measure the angle at which each normal line of each crystal plane of the crystal grain intersects the normal line of the substrate surface. From this measurement result, the (0001) plane and {10-10] which are the constituent crystal planes of the crystal grain } Planes, and in the selected (0001) plane and {10-10} plane, the normal lines of the (0001) plane at the interface between adjacent crystal grains (grain interface unit) and {10-10 } The angle at which the normals of the plane intersect is obtained, and the crystal grain interface unit in which the angle between the normals of the (0001) plane and the normals of the {10-10} plane intersects is 15 degrees or less. Occupy When the ratio (hereinafter referred to as the ratio of crystal grain interface units having an intersection angle of 15 degrees or less) was calculated, the angle at which the normal lines of the (0001) planes intersect with the normal lines of the {10-10} plane was 15 degrees or less. It has been observed that the crystal grain interface unit exhibits a crystal grain interface arrangement that is a ratio of 35% or more of the total crystal grain interface unit, and this crystal grain interface arrangement improves the crystal grain interface strength. It is done.

Therefore, the upper layer of the present invention comprising a modified AlBO layer having a Σ3 interface inside the flat polygonal (including flat hexagonal) long crystal grains and having a surface flat surface property is Excellent wear resistance over a long period of time without any chipping, chipping or peeling even in intermittent heavy cutting of various steels and cast iron, where intermittent and impactful high loads act repeatedly on the blade To demonstrate.
However, if the thickness of the upper layer composed of the modified AlBO layer is less than 1 μm, the superior 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 causative thermoplastic deformation is likely to occur and chipping is also likely to occur. Therefore, the average layer thickness of the upper layer is set to 1 to 15 μm.

As described above, the coated tool of the present invention uses the modified α-type Al ₂ O ₃ layer having excellent high-temperature strength in addition to excellent high-temperature hardness and heat resistance as an intermediate layer and constitutes an upper layer. The modified AlBO layer has a textured structure composed of long and flat crystal grains (including flat hexagons) with surface flatness, and further, a Σ3-compatible interface is formed inside the crystal grains, By strengthening the intra-grain strength, it has both excellent high temperature strength and excellent wear resistance. As a result, various types of steel and cast iron can be subjected to intermittent and shocking high loads on the cutting edge. Even when machined under intermittent heavy cutting conditions, the hard coating layer exhibits excellent chipping resistance, chipping resistance, peeling resistance and excellent wear resistance, further extending the service life Can be realized.

(A) is a plate polygonal crystal grain obtained by observing the upper layer made of the modified AlBO layer of the coated tool 1 of the present invention with a field emission scanning electron microscope in a plane perpendicular to the layer thickness direction. It is a schematic diagram which shows a structure | tissue structure, (b) is a layer surface obtained by observation with the field emission type | mold scanning electron microscope in the plane parallel to a layer thickness direction similarly, and the layer thickness direction is substantially flat. It is a schematic diagram which shows the crystal grain structure which has a long shape, and (c) shows the electric field in the plane perpendicular to the layer thickness direction of the upper layer made of the modified AlBO layer of the coated tool 11 of the present invention. It is a schematic diagram showing a flat hexagonal crystal grain structure obtained by observation with an emission type scanning electron microscope. It is a grain boundary analysis diagram in a plane perpendicular to the layer thickness direction, measured using a field emission scanning electron microscope and an electron backscatter diffraction image device for the upper layer composed of the modified AlBO layer of the coated tool 1 of the present invention, A solid line shows a flat-plate polygonal crystal grain boundary observed with a field emission scanning electron microscope, and a broken line shows a Σ3 corresponding interface measured by an electron backscatter diffraction image apparatus.

  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 6), the Ti compound layer having the target layer thickness shown in Table 6 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 6 is vapor-deposited 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 AlBO layer having the target layer thickness shown in Table 6 as the upper layer of the hard coating layer. Each was manufactured.

Further, for comparison purposes, in the above-described coated tools 1 to 10 of the present invention, the modified AlBO layer as the upper layer was not formed by vapor deposition, but the hard coating layer was formed as the lower layer and the intermediate layer (modified α-type Al ₂ O ₃ layer). The comparative coated tools 1 to 10 (corresponding to the conventional coated tool described in Patent Document 1) shown in Table 7 are produced.

Further, for reference, in the above-described coated tools 11 to 15 of the present invention, the comparative coated tool shown in Table 7 in which the Al ₂ O ₃ layer disclosed in Patent Document 2 is formed by vapor deposition as the upper layer of the hard coated layer. 11 to 15 (corresponding to the conventional coated tool described in Patent Document 2) were produced.

Next, the modified α-type Al ₂ O ₃ layer of the hard coating layer of the present invention-coated tools 1 to 15 and comparative coated tools 1 to 10 using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. The grain interface arrangement was investigated.
That is, the modified α-type Al ₂ O ₃ layer is first set in a lens barrel of a field emission scanning electron microscope in a state where each surface is a polished surface, and an incident angle of 70 degrees to the surface polished surface. An electron backscatter diffraction image apparatus is used to irradiate an electron beam with an acceleration voltage of 15 kV 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. , The angle at which each normal of each crystal plane of the crystal grain intersects the normal of the substrate surface is measured in a 30 × 50 μm region at an interval of 0.1 μm / step. The (0001) plane and {10-10} plane which are crystal planes are selected, and further, in the selected (0001) plane and {10-10} plane, at the interface between adjacent crystal grains (crystal grain interface unit), respectively. (0 The angle at which the normal lines of the (001) plane and the normal lines of the {10-10} plane intersect is obtained, and the angle at which the normal lines of the (0001) plane and the normal lines of the {10-10} plane intersect is 15 degrees. The ratio of the following crystal grain interface units to the total crystal grain interface units (hereinafter referred to as the ratio of crystal grain interface units having an intersection angle of 15 degrees or less) was calculated.
Here, the “surface” 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.
In any of the inventive coated tools 1 to 15 and the comparative coated tools 1 to 10, the modified α-type Al ₂ O ₃ layer is a crystal in which the ratio of crystal grain interface units with an intersection angle of 15 degrees or less is 45% or more. It was confirmed to show a grain interface arrangement.

Next, a field emission scanning electron microscope is used for the modified AlBO layer constituting the upper layer of the hard coating layer of the above-described inventive coated tools 1 to 15 and the Al ₂ O ₃ layer of the hard coating layer of the comparative coated tools 11 to 15. Using an electron backscatter diffraction image apparatus, the grain structure and the constituent atomic shared lattice point morphology were investigated.
That is, first, the modified AlBO layer of the above-described coated tools 1 to 15 and the Al ₂ O ₃ layer of the comparative coated tools 11 to 15 were observed using a field emission scanning electron microscope. 1 to 15 and the comparative coated tools 11 to 15 have a large particle size of a flat plate polygon (including a flat hexagon) and a long and long shape typically shown in FIGS. 1 (a) and 1 (b). (Note that FIG. 1A is a schematic diagram of the structure of the coated tool 1 of the present invention viewed in a plane perpendicular to the layer thickness direction, and FIG. The structure structure schematic diagram which consists of a crystal grain of the flat hexagonal shape and long shape large grain size of this invention coated tool 11 seen in the surface perpendicular | vertical to a layer thickness direction).

Next, with respect to the modified AlBO layer of the above-described inventive coated tools 1 to 15 and the Al ₂ O ₃ layer of the comparative coated tools 11 to 15, crystals having a Σ3-compatible interface inside the crystal grains constituting the respective layers. The area ratio of the grains was measured.
First, the modified AlBO layers of the above-mentioned coated tools 1 to 15 of the present invention were set in a lens barrel of a field emission scanning electron microscope with the surface thereof being a polished surface, 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 represented is represented by ΣN + 1, all crystal grains existing within the measurement range of the modified AlBO 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 values are shown in Table 6.
Next, with respect to the Al ₂ O ₃ layers of the comparative coated tools 11 to 15, the same method as in the case of the coated tool of the present invention, among all the crystal grains existing in the measurement range of the Al ₂ O ₃ layer, Table 7 shows the area ratio of crystal grains in which at least one Σ3-corresponding interface is present inside the grains.

As shown in Tables 6 and 7, the area of crystal grains in which the Σ3-compatible interface exists in both the modified AlBO layer of the present coated tools 1-15 and the Al ₂ O ₃ layer of the comparative coated tools 11-15. It can be seen that the ratio is 60% or more.

Further, the modified AlBO layer of the present coated tools 11 to 15 and the Al ₂ O ₃ layer of the comparative coated tools 11 to 15 are present in a plane perpendicular to the layer thickness direction using a field emission scanning electron microscope. The area ratio of large hexagonal crystal grains having a large particle diameter was determined. These values are shown in Tables 6 and 7.
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

Furthermore, the same method as that measured for the intermediate layer (modified α-type Al ₂ O ₃ layer) of the modified AlBO layer of the coated tools 11 to 15 of the present invention and the Al ₂ O ₃ layer of the comparative coated tools 11 to 15. Then, the angles at which the normal lines of the (0001) plane and the normal lines of the {10-10} plane intersect each other at the interface between adjacent crystal grains (grain interface unit) are obtained, and the normal line of the (0001) plane is obtained. The ratio of the crystal grain interface unit whose angle between the normal lines of each other and the {10-10} planes is 15 degrees or less to the total crystal grain interface unit (hereinafter referred to as the ratio of the crystal grain interface unit whose crossing angle is 15 degrees or less) Was calculated.
These values are shown in Tables 6 and 7.

  Although the thickness of each constituent layer of the hard coating layer of the present invention coated tool 1-15, comparative coated tool 1-10, and comparative coated tool 11-15 was measured using a scanning electron microscope (longitudinal section measurement), In any case, the average layer thickness (average value of 5-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 comparative coated tools 11-15, all are screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / S30C lengthwise equal length 4 round bar with round groove,
Cutting speed: 220 m / min. ,
Cutting depth: 4.0 mm,
Feed: 0.6 mm / rev. ,
Cutting time: 10 minutes,
Of carbon steel under the following conditions (referred to as cutting condition A) (normal cutting speed, feed amount and cutting amount are 200 m / min., 0.4 mm / rev., 3 mm, respectively),
Work material: JIS / SNCM439 round direction bar with 4 equal intervals in the length direction,
Cutting speed: 220 m / min. ,
Cutting depth: 3 mm,
Feed: 0.35 mm / rev. ,
Cutting time: 5 minutes,
Dry-intermittent heavy cutting test of nickel chromium molybdenum alloy steel under the following conditions (referred to as cutting condition B) (normal cutting speed, feed amount and cutting amount are 200 m / min, 0.3 mm / rev., 2 mm, respectively) ,
Work material: JIS / FCD450 lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 200 m / min. ,
Incision: 2 mm,
Feed: 0.45 mm / rev. ,
Cutting time: 5 minutes,
Wet intermittent heavy cutting test of ductile cast iron under the following conditions (referred to as cutting condition C) (normal cutting speed, feed amount and cutting amount are 120 m / min., 0.25 mm / rev., 2 mm, respectively),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 8.

From the results shown in Tables 6 to 8, all of the coated tools 1 to 15 of the present invention have crystal grain interface units in which the modified α-type Al ₂ O ₃ layer, which is an intermediate layer of the hard coating layer, has an intersection angle of 15 degrees or less. The crystal grain interface arrangement with a ratio of 45% or more shows excellent crystal grain interface strength and excellent high-temperature strength, and the modified AlBO layer constituting the upper layer has a long plate polygon (flat hexagonal shape). It has a crystal grain structure and a high area ratio of crystal grains that have at least one Σ3-compatible interface inside the crystal grains, resulting in a much higher surface flatness and a much higher temperature. Combined with strength, or, in addition, the modified AlBO layer has better crystal grain interface strength, and as a result, under intermittent heavy cutting conditions in which intermittent and impactful high loads act repeatedly on the cutting edge. Cutting various steel and cast iron Even if exhibits chipping resistance of the hard coating layer is more excellent, shows excellent wear resistance for a long period of use, and makes it possible to further extend the life of the service life.
On the other hand, in any of the comparative coated tools 1 to 15 in which the modified AlBO layer is not formed as the upper layer of the hard coating layer, the service life can be reached in a relatively short time due to the occurrence of chipping and accelerated wear. it is obvious.

  As described above, the coated tool of the present invention is not only for cutting under normal conditions such as various types of steel and cast iron, but also for intermittent heavy cutting in which intermittent and impactful high loads act repeatedly on the cutting edge. However, it exhibits excellent wear resistance without chipping, and exhibits excellent cutting performance over a long period of time. It is possible to cope with the conversion sufficiently 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) a modified aluminum oxide layer having an average layer thickness of 1 to 5 μm and having an α-type crystal structure in the state of chemical vapor deposition;
(C) a B-containing aluminum oxide layer having an average layer thickness of 1 to 15 μm and having an α-type crystal structure in the state of chemical vapor deposition;
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 a hexagonal crystal lattice formed by using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus to irradiate each crystal grain existing within the measurement range of the surface polished surface with an electron beam. The angle at which each normal line of each crystal plane of the crystal grain has a normal line on the substrate surface is measured, and from this measurement result, the (0001) plane and {10-10} which are the constituent crystal planes of the crystal grain In addition, in the selected (0001) plane and {10-10} plane, the normal lines of the (0001) plane at the interface between adjacent crystal grains (grain interface unit) and {10-10} When the angle at which the surface normals intersect is determined, the crystal grain interface unit in which the angle between the normals of the (0001) surface and the normals of the {10-10} surface intersects each other is 15 degrees or less. Over 45% of interface units A modified aluminum oxide layer showing a crystal grain interface sequences occupying,
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 B-containing aluminum oxide layer having a structure composed of crystal grains having a vertically long shape,
Further, the upper layer has a hexagonal crystal lattice by irradiating individual crystal grains existing within the measurement range of the surface polished surface with a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Measure the angle at which each normal of each crystal plane of the crystal grain intersects the normal of the substrate surface, and from this measurement result, calculate the crystal orientation relationship between adjacent crystal lattices, and configure 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) the existing constituent atoms When representing the lattice points form in .SIGMA.N + 1,
Among the crystal grains constituting the upper layer, the interior of the crystal grains having an area ratio of 60% or more is divided by at least one crystal lattice interface composed of a constituent atomic shared lattice point represented by Σ3. B-containing aluminum oxide layer
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 upper layer of (c) uses a field emission scanning electron microscope and an electron backscatter diffraction image apparatus to irradiate each crystal grain existing within the measurement range of the surface polished surface with an electron beam, thereby forming a hexagonal crystal lattice. The angle at which each normal line of each crystal plane of the crystal grain has a normal line on the substrate surface is measured, and from this measurement result, the (0001) plane and {10-10} which are the constituent crystal planes of the crystal grain In addition, in the selected (0001) plane and {10-10} plane, the normal lines of the (0001) plane at the interface between adjacent crystal grains (grain interface unit) and {10-10} When the angle at which the surface normals intersect is determined, the crystal grain interface unit in which the angle between the normals of the (0001) surface and the normals of the {10-10} surface intersects each other is 15 degrees or less. Over 35% of interface units The surface-coated cutting tool according to claim 1 or 2 which is a B-containing aluminum oxide layer showing a crystal grain interface sequences occupying.

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