JP6288606B2 - Surface coated cutting tool with excellent chipping resistance and wear resistance with hard coating layer - Google Patents

Description

  The present invention provides a surface in which a hard coating layer exhibits excellent chipping resistance and wear resistance over a long period of use even when various types of steel and cast iron are cut under high-speed cutting conditions with high heat generation. The present invention relates to a coated cutting tool (hereinafter referred to as a coated tool).

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) As a 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, carbon oxide (hereinafter referred to as TiCO) A Ti compound layer comprising one or more of a layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) As an upper layer, an aluminum oxide layer,
A coated tool formed by vapor-depositing a hard coating layer comprising the above (a) and (b) is well known.

In the conventional coated tool, various proposals have been made to improve the tool performance.
For example, as shown in Patent Document 1, in forming the aluminum oxide layer (b), a Zr-containing κ-Al ₂ O ₃ layer having excellent heat shielding properties and excellent mechanical and thermal shock resistance In addition, when the upper layer is formed by alternately laminating heat-transformed α-Al ₂ O ₃ layers having excellent high-temperature hardness and heat resistance, chipping resistance in heavy cutting work where a large load acts on the cutting edge It is known that the wear resistance is improved.

Japanese Patent No. 5029825

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 in cutting work, and cost reduction. In the conventional coated tool, there is no problem when this is used for continuous cutting under normal conditions such as steel and cast iron, but especially when this is used for high-speed cutting conditions with high heat generation, Al ₂ O ₃ of the κ-type crystal structure of the upper layer of the hard coating layer (hereinafter, κ-type crystal structure Al ₂ O _{3 is represented} by “κ-Al ₂ O ₃ ”, and α-type crystal structure of Al ₂ O 3 _{3 is represented} by “α-Al ₂ O ₃ ”). Residual stress is generated in the upper layer by the volume shrinkage accompanying the transformation from the κ-type crystal structure to the α-type crystal structure, and the progress of cracks is promoted. For this reason, chipping, chipping and peeling are particularly likely to occur at the cutting edge. Ri, as a result, at present, leading to a relatively short time service life.

  Therefore, the present inventors have conducted earnest research to improve the chipping resistance and wear resistance of the hard coating layer in high-speed cutting from the above viewpoint, and as a result, obtained the following knowledge. .

In order to alleviate the volume change associated with the κ → α transformation in the Al ₂ O ₃ layer constituting the hard coating layer of the coated tool, the present inventors used the κ-Al ₂ O ₃ layer as a base material. When α-Al ₂ O ₃ is dispersed and distributed in the substrate at a certain ratio, volume shrinkage due to the κ → α transformation can be reduced. Therefore, α-Al _{2 is} added to the κ-Al ₂ O _3- layer substrate. It has been found that the chipping resistance is improved by the layer structure in which O ₃ is dispersed.

Further, in the α-Al ₂ O ₃ in κ-Al ₂ O ₃ layer in the matrix of the hard coat layer to disperse distribution at a constant rate, in accordance with the upper layer thickness deposition proceeds becomes thicker, alpha-Al ₂ Since the O ₃ crystal grains tend to grow and become coarse, when the κ-Al ₂ O ₃ layer constituting the substrate of the hard coating layer reaches a predetermined thickness, the film formation is temporarily interrupted, and α-Al ₂ O ₃ After forming the dividing line that divides the growth of the crystal grains, the base κ-Al ₂ O ₃ layer is subsequently formed (in this case, the growth of the α-Al ₂ O ₃ crystal grains is also started). If the film formation of the κ-Al ₂ O ₃ layer and the split layer are alternately repeated, coarse α-Al ₂ O ₃ crystal grains are not formed in the hard coating layer. It has been found that the wear resistance of the hard coating layer is improved in addition to the improvement of chipping resistance.

Furthermore, the present inventors have, _κ-Al 2 _{O 3} layer green body is dispersed _α-Al 2 _{O 3} crystal grains, upon relaxing the volumetric shrinkage due to the kappa → alpha transformation, _α-Al 2 _{O 3} crystal grains When the (11-20) orientation degree of the α-Al ₂ O ₃ crystal grains dispersed in the κ-Al ₂ O ₃ layer substrate on the tool base side is increased, the α-Al ₂ O ₃ is increased at a high temperature. It has been found that the crystal grains undergo a large volume expansion in the layer thickness direction, which acts in a direction to cancel the volume shrinkage associated with the κ → α transformation.
However, (11-20) α-Al ₂ O ₃ crystal grains having a high degree of orientation have insufficient wear resistance, and therefore α- dispersed in the κ-Al ₂ O ₃ layer substrate on the hard coating layer surface side. The Al ₂ O ₃ crystal grains are desirably composed of α-Al ₂ O ₃ crystal grains having a high degree of orientation (10-14) having excellent wear resistance.
That is dispersed in _κ-Al 2 _{O 3} layer in the matrix of the hard layer _α-Al 2 _{O 3} crystal grains, a tool substrate side (11-20) of high degree of orientation _α-Al 2 _{O 3} crystal grains On the other hand, it is desirable that the hard coating layer surface side is composed of α-Al ₂ O ₃ crystal grains having a high degree of (10-14) orientation.
And it has been found that the hard coating layer has such a layer structure, so that it has not only excellent chipping resistance but also excellent wear resistance even under high-speed cutting conditions with high heat generation. It is.

The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper layer is deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The lower layer has a total average layer thickness of 3 to 20 μm composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer. Consisting of a Ti compound layer,
(B) The upper layer has an average layer thickness of 2 to 15 μm, and has an alternately stacked structure in which three or more aluminum oxide layers are alternately stacked via a dividing layer,
(C) The alternately laminated aluminum oxide layers have an average layer thickness of 0.5 to 4 μm per layer, and Al ₂ O having an α-type crystal structure in an Al ₂ O ₃ substrate having a κ-type crystal structure. Having a structure in which a dispersed phase composed of _three crystal grains is dispersed and distributed;
(D) The average area ratio of the dispersed phase in the Al ₂ O ₃ substrate of the κ-type crystal structure measured in the longitudinal section of the aluminum oxide layer of the alternately laminated structure is 20 to 60 area%,
(E) The dispersion phase in the aluminum oxide layer from the surface side of the aluminum oxide layer having the alternately laminated structure to at least the first layer is measured using a field emission scanning electron microscope, and the measurement range of the polished surface parallel to the tool substrate surface The crystal grains having a hexagonal crystal lattice existing therein are irradiated with an electron beam, and the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, with respect to the normal line of the polished surface Of the measured tilt angles, and the measured tilt angles within the range of 0 to 45 degrees are divided into pitches of 0.25 degrees, and the tilt angles obtained by counting the frequencies existing in each section In the number distribution graph, the highest peak exists in the inclination angle section within the range of 30 to 45 degrees, and the total of the frequencies existing within the range of 30 to 45 degrees is 50 of the entire degrees in the inclination angle number distribution graph. % Or more Indicates the inclination angle frequency distribution graph occupied,
(F) The surface-coated cutting tool, wherein the dividing layer is composed of any one of a Ti carbide layer, a nitride layer, and a carbonitride layer having an average layer thickness of 0.1 to 1.5 μm per layer.
(2) In the surface-coated cutting tool according to (1),
Dispersed phase in the aluminum oxide layer from the substrate side of the aluminum oxide layer to at least a first layer of the alternate laminated structure, using a field emission scanning electron microscope, within the measuring range of the surface and parallel to the polishing surface of the tool substrate Irradiate each individual crystal grain having a hexagonal crystal lattice with an electron beam, and measure the inclination angle formed by the normal of the (0001) plane, which is the crystal plane of the crystal grain, with respect to the normal of the polished surface And, among the measured tilt angles, the measured tilt angles within a range of 45 to 90 degrees are divided into pitches of 0.25 degrees, and the tilt angle number distribution is obtained by counting the frequencies existing in each section. In the graph, the highest peak exists in the inclination angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees is 50% of the entire degrees in the inclination angle number distribution graph. Above The surface-coated cutting tool according to, characterized in that shows the inclination angle frequency distribution graph occupying (1). "
It has the characteristics.

Below, the hard coating layer of the coated tool of this invention is demonstrated in detail.
In FIG. 1, the longitudinal cross-sectional schematic diagram of the hard coating layer of this invention coated tool is shown.
FIG. 2 is a schematic diagram showing a middle stage of film formation before a separation layer is vapor-deposited on the lower layer vapor-deposited on the tool base surface and an aluminum oxide layer is vapor-deposited.

Lower layer:
As shown in FIG. 1, the lower Ti compound layer includes Ti carbide (TiC) layer, nitride (TiN) layer, carbonitride (TiCN) layer, carbonate (TiCO) layer and carbonitride oxide ( It is composed of one or more of (TiCNO) layers.
The Ti compound layer exists as the lower layer of the upper layer composed of an alternating layered structure, and contributes to improving the high temperature strength of the hard coating layer by its excellent high temperature strength, and is strong to both the tool base and the upper layer. It has an effect of improving the adhesion of the hard coating layer to the tool substrate, but if the average layer thickness is less than 3 μm, the above-mentioned effect cannot be fully exhibited, while the average layer thickness is 20 μm. If it exceeds, especially high-speed cutting accompanied by generation of high heat is likely to cause thermoplastic deformation, which causes uneven wear, so the average layer thickness was determined to be 3 to 20 μm.

Upper layer:
As shown in FIG. 1, the upper layer has an alternate stacked structure in which aluminum oxide layers are alternately stacked via a dividing layer.
By forming the dividing layer, the α-Al ₂ O ₃ crystal grains dispersed and distributed in the aluminum oxide layer are prevented from growing and coarsening as the film formation progresses and the upper layer thickness increases.
If the average thickness of the upper layer is less than 2 μm, sufficient wear resistance cannot be exhibited over a long period of use. On the other hand, if it exceeds 15 μm, abnormal damage such as chipping, chipping or peeling tends to occur. Therefore, the average layer thickness of the upper layer was set to 2 to 15 μm.

Split fault:
As shown in FIG. 1, the dividing line is a layer that is formed between the lower layer and the upper layer, further divides the upper aluminum oxide layer, and configures the upper layer as an alternately laminated structure.
The dividing layer is composed of any one of a Ti carbide layer, a nitride layer, and a carbonitride layer having a layer thickness of 0.1 to 1.5 μm.
Before the aluminum oxide layer is vapor-deposited on the lower layer formed on the surface of the tool base by the chemical vapor deposition apparatus, the split layer is formed by interposition, and further, the aluminum oxide layer is divided by the split layer to thereby form aluminum oxide. An upper layer having an alternately laminated structure of layers and dividing layers is formed.
By dividing the aluminum oxide layer with a dividing layer, it is possible to prevent the α-Al ₂ O ₃ crystal grains in the aluminum oxide layer from becoming coarse, so that the high hardness of the upper layer can be maintained, and the surface An upper layer having excellent smoothness can be formed.
If the layer thickness of the dividing layer is less than 0.1 μm per layer, the dividing effect for suppressing the growth coarsening of α-Al ₂ O ₃ crystal grains is small, while the layer thickness of the dividing layer is 1.5 μm per layer. Since the wear resistance of the upper layer tends to be lower than the upper limit, the layer thickness of the dividing layer is determined to be 0.1 to 1.5 μm per layer.

Formation of a split fault:
The Ti carbide layer, nitride layer, and carbonitride layer in the split layer may be formed according to a conventionally known vapor deposition method.
Furthermore, after film formation of the dividing line, for example,
With normal chemical vapor deposition equipment,
Reaction gas (volume%):
TiCl _4: 0.5~1.5%,
CO ₂ : 3 to 10%,
Ar: 25-35%
H ₂ : Remaining
Reaction atmosphere temperature: 880-980 ° C.,
Reaction atmosphere pressure: 4 to 70 kPa,
Reaction time: 1-30 min
Under the conditions, Ti oxide formation processing is performed on the surface of the dividing layer.
By forming an aluminum oxide layer on the surface of the split layer subjected to the Ti oxide formation treatment, κ-Al ₂ O ₃ crystal grains are used as a base material, and α-Al ₂ O ₃ crystal grains are dispersed in the base material. As a result, an aluminum oxide layer having a distributed structure can be formed.

As shown in FIG. 2, when the Ti oxide formation process is performed on the surface of the dividing layer, a Ti oxide represented by the composition formula: TiO _X is formed on the surface of the dividing layer. Since it is selectively formed at the grain boundary of the layer, it affects the growth and content ratio of the α-Al ₂ O ₃ crystal grains in the aluminum oxide layer based on the κ-Al ₂ O ₃ crystal grains.
That is, when forming an aluminum oxide layer on the surface of the dividing layer, on the Ti oxide formed on the surface of the dividing layer (more precisely, Ti oxide selectively formed on the grain boundary of the intermediate layer). Since α-Al ₂ O ₃ crystal grains grow preferentially, while κ-Al ₂ O ₃ crystal grains preferentially grow in other regions, the structure of the aluminum oxide layer is as follows: By using κ-Al ₂ O ₃ crystal grains as a base, an aluminum oxide layer having a structure in which α-Al ₂ O ₃ crystal grains are dispersed and distributed as a dispersed phase in the base can be formed.
If the outermost surface layer of the lower layer is formed of any one of a Ti carbide layer, a nitride layer, and a carbonitride layer during vapor deposition of the first aluminum oxide layer on the substrate side, this is Since it corresponds to a dividing line, it is not necessary to form a dividing line on the lower layer again, but it is necessary to perform a Ti oxide formation process on this.

Upper aluminum oxide layer:
An aluminum oxide layer constituting an alternating stack of upper layers has a structure in which dispersed phases composed of α-Al ₂ O ₃ crystal grains are dispersed and distributed in a base composed of κ-Al ₂ O ₃ crystal grains.
And with such a structure, volume shrinkage due to κ → α transformation of the upper layer in high-speed cutting conditions with high heat generation such as steel and cast iron can be reduced, and the occurrence of residual stress in the upper layer is suppressed. Can do. As a result, the progress of cracks in the upper layer can be suppressed, and the chipping resistance of the cutting edge is improved.
The aluminum oxide layer constituting the alternating lamination of the upper layers needs to have an average layer thickness of 0.5 to 4 μm per layer.
When the layer thickness per layer of the aluminum oxide layers constituting the alternating lamination is less than 0.5 μm, satisfactory wear resistance cannot be exhibited over a long period of use, while the layer thickness per layer exceeds 4 μm. In this case, since the dispersed phase composed of α-Al ₂ O ₃ crystal grains dispersed and distributed in the substrate composed of κ-Al ₂ O ₃ crystal grains grows coarsely, the surface roughness of the upper layer increases, and chipping resistance The layer thickness per layer needs to be 0.5 to 4 μm because the properties and wear resistance tend to decrease.

Ratio of dispersed phase in the aluminum oxide layer constituting the upper layer:
The vertical vertical section of the aluminum oxide layer was observed with a scanning electron microscope (SEM) equipped with a backscattering electron diffractometer (EBSD), and image analysis of the obtained crystal orientation mapping image revealed that κ-Al ₂ When the area ratio of the dispersed phase composed of α-Al ₂ O ₃ crystal grains in the O ₃ substrate is measured and the area ratio of the dispersed phase is less than 20% by area, the volume shrinkage accompanying the κ → α transformation On the other hand, if the area ratio exceeds 60 area%, the heat shielding effect by the κ-Al ₂ O ₃ substrate is insufficient, and therefore the κ-Al ₂ O ₃ substrate is occupied. The area ratio of the dispersed phase is 20 to 60 area%.

Crystal orientation of the dispersed phase:
Dispersion distribution of the dispersed phase composed of α-Al ₂ O ₃ crystal grains in the κ-Al ₂ O ₃ substrate alleviates the volume change due to the κ → α transformation, but the dispersed phase is α-Al _2. The characteristics of the upper layer are greatly affected by the plane orientation of the O ₃ crystal grains.
That is, α-Al ₂ O ₃ crystal grains have a larger coefficient of thermal expansion in the parallel direction (c-axis direction) than in the direction perpendicular to the normal direction of the (0001) plane (a-axis direction). . Therefore, if the (11-20) orientation degree of the α-Al ₂ O ₃ crystal grains in the dispersed phase is increased, the α-Al ₂ O ₃ crystal grains are subjected to large volume expansion in the layer thickness direction at a high temperature, thereby forming a substrate. It acts in a direction to cancel the volume shrinkage accompanying the κ → α transformation of the κ-Al ₂ O ₃ crystal grains.
However, (11-20) α-Al ₂ O ₃ crystal grains having a high degree of orientation have insufficient wear resistance compared to α-Al ₂ O ₃ crystal grains having a high degree of (10-14) orientation. .
Therefore, in order to satisfy both chipping resistance and wear resistance in high-speed cutting conditions with high heat generation such as steel and cast iron, as shown in FIG. For the aluminum oxide layer positioned from the substrate side to at least the first layer, the dispersed phase composed of (11-20) highly oriented α-Al ₂ O ₃ crystal grains is dispersed and distributed, while the alternate stacked structure is formed. For the aluminum oxide layer located from the surface side to at least the first layer of the constituent aluminum oxide layers, a dispersed phase composed of α-Al ₂ O ₃ crystal grains having a high degree of orientation (10-14) is dispersed and distributed. It is desirable.

Measurement of crystal orientation in the dispersed phase:
The crystal orientation of the dispersed phase can be performed as follows.
That is, in order to measure the degree of orientation of the (11-20) plane of the dispersed phase in the aluminum oxide layer located from the substrate side to at least the first layer, a field emission scanning electron microscope is used. The crystal grains having a hexagonal crystal lattice existing in the measurement range of the polished surface parallel to the electron beam are irradiated with an electron beam, and are the crystal planes of the crystal grains with respect to the normal line of the polished surface (0001) The inclination angle formed by the normal of the surface is measured, and among the measurement inclination angles, the measurement inclination angles within the range of 45 to 90 degrees are divided for each pitch of 0.25 degrees and exist in each division. In the inclination angle frequency distribution graph obtained by counting the frequencies, the sum of the frequencies existing in the range of 75 to 90 degrees is obtained, and the ratio of the total frequency to the entire frequency in the inclination angle frequency distribution graph is calculated. By (11-20) plane Mukodo can be obtained.
In the inclination angle number distribution graph obtained above, the highest peak of frequency exists in the inclination angle section within the range of 75 to 90 degrees, and the frequency ratio existing in the inclination angle section of 75 to 90 degrees is 50% or more. In this case, the (11-20) plane orientation degree of the dispersed phase in the aluminum oxide layer located from the substrate side to at least the first layer is high, and on the substrate side, the volume change associated with the κ → α transformation is alleviated. Is sufficiently performed and chipping resistance is improved. In the inclination angle number distribution graph, the highest peak of the frequency exists in the inclination angle section within the range of 75 to 90 degrees, and the inclination angle section It is desirable that the frequency ratio existing in is 50% or more.

Further, in order to measure the degree of orientation of the (10-14) plane of the dispersed phase in the aluminum oxide layer located from the surface side to at least the first layer, a field emission scanning electron microscope was used to measure the surface of the tool substrate. The crystal grains having a hexagonal crystal lattice existing in the measurement range of the polished surface parallel to the electron beam are irradiated with an electron beam, and are the crystal planes of the crystal grains with respect to the normal line of the polished surface (0001) The tilt angle formed by the normal of the surface is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees and exist in each section. In the inclination angle frequency distribution graph obtained by counting the frequencies, the total of the frequencies existing in the range of 30 to 45 degrees is obtained, and the ratio of the total frequency to the total frequency in the inclination angle frequency distribution graph is calculated. By (10-14) plane arrangement Degree can be obtained.
In the inclination angle number distribution graph obtained above, the highest peak of frequency exists in the inclination angle section within the range of 30 to 45 degrees, and the frequency ratio existing in the inclination angle section of 30 to 45 degrees is 50% or more. In this case, the (10-14) plane orientation degree of the dispersed phase in the aluminum oxide layer located from the surface side to at least the first layer is high, and high hardness is ensured on the surface side of the upper layer and wear resistance. Since the improvement is intended, in the inclination angle distribution graph, the highest peak of the frequency exists in the inclination angle section within the range of 30 to 45 degrees, and the frequency ratio existing in the inclination angle section is 50% or more. It is desirable that

Formation of the upper layer:
For the upper layer, first, a dividing layer having a predetermined layer thickness is formed on the surface of the lower layer, an aluminum oxide layer having a predetermined layer thickness is formed thereon, and the forming of the dividing layer and the forming of the aluminum oxide layer are alternately performed. To the target number of layers and the target average layer thickness.
The method of forming the dividing layer is as described above, but the aluminum oxide layer can be formed as follows.

<< Filming of an aluminum oxide layer located from the substrate side to at least the first layer >>
For example, with a normal chemical vapor deposition device,
Reaction gas (volume%):
AlCl ₃ : 1 to 5%,
CO _2: 3~7%,
HCl: 0.3-3%,
H ₂ S: 0.02~0.4%,
H ₂ : Remaining
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 20-30 kPa,
By vapor deposition under the conditions, an aluminum oxide layer having a base of κ-Al ₂ O ₃ crystal grains located from the substrate side to at least the first layer is formed. At the same time, in the inclination angle number distribution graph, Α-Al ₂ O ₃ crystal grains ((11-20) in which the highest peak of power exists in the tilt angle section in the range of 75 to 90 degrees and the power ratio in the tilt angle section is 50% or more. The dispersed phase consisting of (a) α-Al ₂ O ₃ crystal grains having a high degree of plane orientation is dispersed and distributed in the κ-Al ₂ O ₃ crystal grain base.

<< Formation of an aluminum oxide layer located from the surface side to at least the first layer >>
For example, with a normal chemical vapor deposition device,
Reaction gas (volume%):
AlCl ₃ : 3 to 10%,
CO _2: 0.5~3%,
HCl: 0.3-3%,
SF ₆ : 0.01 to 0.2%,
C ₂ H _4: 0.01~0.3%,
H ₂ : Remaining
Reaction atmosphere temperature: 950 to 1000 ° C.
Reaction atmosphere pressure: 20-30 kPa,
By vapor deposition under the conditions, an aluminum oxide layer based on κ-Al ₂ O ₃ crystal grains located from the surface side to at least the first layer is formed, and at the same time, in the inclination angle number distribution graph, Α-Al ₂ O ₃ crystal grains ((10-14) in which the highest peak of frequency exists in the inclination angle section within the range of 30 to 45 degrees and the frequency ratio existing in the inclination angle section is 50% or more. The dispersed phase consisting of (a) α-Al ₂ O ₃ crystal grains having a high degree of plane orientation is dispersed and distributed in the κ-Al ₂ O ₃ crystal grain base.

In the coated tool of the present invention, the upper layer of the hard coating layer is configured as an alternately laminated structure of an aluminum oxide layer and a split layer, and a dispersed phase composed of α-Al ₂ O ₃ crystal grains is dispersed and distributed in the aluminum oxide layer. In addition, by specifying the crystal orientation degree of the dispersed phase, the volume change associated with the κ → α transformation is relaxed, the growth coarsening of α-Al ₂ O ₃ crystal grains is prevented, and the surface side Since the aluminum oxide layer has particularly high hardness, it has excellent chipping resistance and wear resistance even when cutting various types of steel and cast iron under high-speed cutting conditions with high heat generation. It exhibits excellent cutting performance and enables further extension of the service life.

The longitudinal cross-sectional schematic diagram of the hard coating layer of this invention coated tool is shown. The schematic diagram of the middle stage of the film-forming which vapor-deposited the dividing layer on the lower layer vapor-deposited on the tool base surface is shown. An example of the inclination angle number distribution graph measured and created about the 1st layer from the tool base | substrate side of the aluminum oxide layer of this invention coated tool is shown. An example of the inclination angle number distribution graph measured and created about the 1st layer from the surface side of the aluminum oxide layer of this invention coated tool is shown. An example of the inclination angle number distribution graph created about the aluminum oxide layer of the comparative example covering tool is shown.

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

  As raw material powders, the powders shown in Table 1 each having an average particle diameter of 1 to 3 μm were prepared. These raw material powders were blended into the blending composition shown in Table 1, and further wax was added in acetone. After ball mill mixing for a period of time and drying under reduced pressure, the green compact was press-molded into a green compact of a predetermined shape at a pressure of 98 MPa, and this green compact was held at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. WC-based cemented carbide tool substrate A having an insert shape defined in ISO / CNMG120408 by performing a sintering process under vacuum conditions and performing a honing process of R: 0.07 mm on the cutting edge after sintering. Each E was produced.

  In addition, as the raw material powder, the powders shown in Table 2 each having an average particle diameter of 0.5 to 2 μm were prepared, and these raw material powders were blended into the blending composition shown in Table 2 and wetted by a ball mill for 24 hours. After mixing and drying, the green compact was press-molded into a green compact at a pressure of 98 MPa, and the green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour and after sintering. Then, the tool bases a to e made of TiCN-based cermet having an ISO standard / CNMG120408 insert shape were produced by performing a honing process of R: 0.07 mm on the cutting edge portion.

Next, each of these tool bases A to E and tool bases a to e was charged into a normal chemical vapor deposition apparatus, and Table 3 (l-TiCN in Table 3 is described in JP-A-6-8010). The target layer thicknesses shown in Table 6 under the conditions shown in Table 6 are the conditions for forming a TiCN layer having a vertically grown crystal structure. The Ti compound layer was deposited as a lower layer of the hard coating layer.
Next, a split layer having a target layer thickness is formed by vapor deposition under the conditions shown in Table 3, and Ti oxide is formed on the surface of the split layer under any one of the type symbols a1 to a4 shown in Table 4. A forming process was applied.
Next, an upper aluminum oxide layer is formed by vapor deposition under the conditions of either type symbol A or B shown in Table 5, and a separation layer is formed by vapor deposition under the conditions shown in Table 3 and Table 4. By alternately depositing layers and dividing layers, an upper layer having an alternate laminated structure having a target layer thickness shown in Table 7 is formed by vapor deposition. As a hard coating layer, lower layers shown in Table 6 and Table 7 are formed. Present invention coated tools 1 to 5 and reference example coated tools 6 to 10 each having a dividing line and an aluminum oxide layer shown were manufactured.
That is, α-Al ₂ O ₃ crystal grains, which are dispersed phases in the aluminum oxide layers of the inventive coated tools 1 to 5 and the reference example coated tools 6 to 10, are dispersed from the first layer on the substrate side of the aluminum oxide layer. The same crystal orientation is provided up to the outermost layer, but the coated tools 1 to 5 of the present invention are the conditions of the type symbol B shown in Table 5, and the reference coated tools 6 to 10 are: Under the condition of the type symbol A shown in Table 5, the aluminum oxide layer of each upper layer is formed by vapor deposition .

Further, in order to examine the influence of the orientation of α-Al ₂ O ₃ crystal grains, which are dispersed phases distributed and distributed in the aluminum oxide layer, α-Al having a high degree of orientation (11-20) on the substrate side of the aluminum oxide layer. ₂ O ₃ to form a crystal grain, on the other hand, had a surface of the aluminum oxide layer present invention coated tool 11 to 20 forming the (10-14) high orientation degree _alpha-Al 2 _{O 3} crystal grains produced respectively.
That is, in the manufacturing process of the present invention coated tools 1 to 10, under the conditions shown in Table 3, after forming a partial layer consisting of an intermediate layer having a target layer thickness and a Ti oxide thin layer, the substrate side is An aluminum oxide layer is formed under the conditions of A shown in Table 5 to form α-Al ₂ O ₃ crystal grains having a high degree of (11-20) orientation, while on the surface side, B shown in Table 5 is formed. By forming an aluminum oxide layer under the conditions and forming α-Al ₂ O ₃ crystal grains having a high degree of (10-14) orientation, the hard coating layer is shown in the lower layer shown in Table 6 and in Table 8. The coated tools 11 to 20 of the present invention each having a split layer and an aluminum oxide layer were manufactured.

For comparison, each of the tool bases A, B, and C and the tool bases a, b, and c is charged into a normal chemical vapor deposition apparatus, and the target layer shown in Table 6 is used under the conditions shown in Table 3. A thick Ti compound layer was deposited as a lower layer of the hard coating layer.
Next, a normal κ-Al ₂ O ₃ layer is deposited at a predetermined target layer thickness under the condition of the type symbol C shown in Table 5, and the normal α is added under the condition of the type symbol D shown in Table 5. -Al ₂ O ₃ layer is formed by vapor deposition with a predetermined target layer thickness, and this is alternately repeated to form an aluminum oxide having an alternating laminated structure of κ-Al ₂ O ₃ layers and α-Al ₂ O ₃ layers The layers were formed so as to have a target layer thickness, and comparative example-coated tools 1 to 6 each having a lower layer shown in Table 5 and an aluminum oxide layer shown in Table 9 were produced.

Further, for comparison, each of the tool bases D and E and the tool bases d and e is charged into a normal chemical vapor deposition apparatus, and Ti having the target layer thickness shown in Table 6 under the conditions shown in Table 3 is used. The compound layer was deposited as a lower layer of the hard coating layer.
Next, a normal α-Al ₂ O ₃ single-layer aluminum oxide layer was formed to a target layer thickness under the condition of the type symbol D shown in Table 5, and the lower layer shown in Table 5 and Table 9 were formed. Comparative example-coated tools 7 to 10 each having an aluminum oxide layer shown in FIG.

About the said invention coated tools 1-5 , 11-20 , and reference example coated tools 6-10 , as a disperse phase in the aluminum oxide layer of an upper layer using a field emission type scanning electron microscope and an electron backscattering diffraction image apparatus together determine the area ratio of the present _α-Al 2 _{O 3} crystal grains were measured _α-Al 2 _{O 3} crystal grains (11-20) plane or (10-14) plane orientation degree.
That is, the area ratio of α-Al ₂ O ₃ crystal grains was measured as follows.
The vertical vertical section of the aluminum oxide layer was observed with a scanning electron microscope (SEM) equipped with a backscattering electron diffractometer (EBSD), and image analysis of the obtained crystal orientation mapping image revealed that κ-Al ₂ The area ratio of the dispersed phase consisting of α-Al ₂ O ₃ crystal grains in the O ₃ substrate was measured.

  The (11-20) plane orientation degree was set in a lens barrel of a field emission scanning electron microscope with the aluminum oxide layer cross section from the substrate side to the predetermined number of layers as a polished surface, and the tool substrate. Each of the crystal grains having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the surface is irradiated 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, Using an electron backscatter diffraction image apparatus, the normal of the (0001) plane, which is the crystal plane of the crystal grain, is defined with respect to the normal of the polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step. Measure the tilt angle, and divide the measured tilt angles within the range of 45 to 90 degrees for each pitch of 0.25 degrees, and totalize the frequencies existing in each section. Create a slope angle distribution graph that will be the highest peak In addition to obtaining the existing inclination angle section, the degree of (11-20) plane orientation is obtained by obtaining the ratio of the total frequency existing in the range of 75 to 90 degrees to the entire frequency in the inclination angle frequency distribution graph. It was.

  The (10-14) plane orientation degree was set in the barrel of a field emission scanning electron microscope with the aluminum oxide layer cross section from the surface side to the predetermined number of layers as a polished surface, and the tool substrate Each of the crystal grains having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the surface is irradiated 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, Using an electron backscatter diffraction image apparatus, the normal of the (0001) plane, which is the crystal plane of the crystal grain, is defined with respect to the normal of the polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step. Measure the inclination angle to be made, divide the measurement inclination angle within the range of 0-45 degrees out of the measurement inclination angle for each pitch of 0.25 degree, and totalize the frequency existing in each division Create a slope angle number distribution graph that (10-14) The degree of orientation of the plane is obtained by obtaining the ratio of the existing inclination angle and obtaining the ratio of the total frequency existing in the range of 30 to 45 degrees to the whole frequency in the inclination angle frequency distribution graph. It was.

In addition, for the comparative coated tools 1 to 10, the inclination angle number distribution graph was prepared in the same manner as described above, and the (11-20) plane orientation degree and (10-14) plane orientation degree were measured.
Tables 7 to 9 show these results.
FIGS. 3 to 5 show examples of measured and created inclination angle number distribution graphs. The coated tool of the present invention in FIG. 3 has a (11-20) orientation degree of the dispersed phase in the aluminum oxide on the substrate side. It can be seen that the inventive coated tool of FIG. 4 has a high degree of (10-14) orientation of the dispersed phase in the aluminum oxide on the surface side.
On the other hand, it can be seen that the comparative coated tool shown in FIG. 5 (the dispersed phase does not exist in the aluminum oxide layer) does not show special orientation.

Further, the thicknesses of the constituent layers of the hard coating layers of the inventive coated tools 1 to 5 , 11 to 20, the reference example coated tools 6 to 10 and the comparative example coated tools 1 to 6 are measured using a scanning electron microscope. As a result of (longitudinal section measurement), all showed an average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness.
Tables 7 to 9 show the above results.

Next, for the above-described inventive coated tools 1 to 5 , 11 to 20, reference example coated tools 6 to 10 and comparative example coated tools 1 to 10 , all are screwed with a fixing jig at the tip of the tool steel tool. In the stopped state,
Work material: JIS / SCM440 round bar,
Cutting speed: 420 m / min,
Incision: 1.5mm,
Feed: 0.3mm / rev,
Cutting time: 5 minutes
The dry high-speed cutting test of the alloy steel under the above conditions (referred to as cutting condition A) was performed, the flank wear width of the cutting edge was measured, and the damage form of the cutting edge was observed.
Table 10 shows the results.

From Tables 6 to 9, the present invention coated tools 1 to 5 and the reference example coated tools 6 to 10 are formed from α-Al ₂ O ₃ crystal grains on the κ-Al ₂ O ₃ crystal base material of the upper layer of the hard coating layer. The dispersed phase to be distributed shows excellent wear resistance although fine chipping is observed in the coated tools 1 to 5 of the present invention, and chipping occurs in the reference coated tools 6 to 10. Excellent wear resistance.
Further, the present invention coated tool 11-20, the base side of the _κ-Al 2 _{O 3} grain matrix of the upper layer of the hard layer, from (11-20) is higher orientation degree _α-Al 2 _{O 3} crystal grains The dispersed phase is dispersed and distributed, and the κ-Al ₂ O ₃ crystal base material on the surface side of the upper layer of the hard coating layer is made of α-Al ₂ O ₃ crystal grains having a high degree of orientation (10-14). When the dispersed phase is dispersed and distributed, chipping resistance and wear resistance are further improved.

In contrast, in Comparative Example coated tools 1 to 6, the wear occurs involving chipping, In Comparative coated tool 7 to 10, the abrasion occurs with the deformation of the cutting edge, is clear that the lead in a short time in the life is there.

As described above, the coated tool of the present invention exhibits excellent chipping resistance not only in continuous cutting and intermittent cutting under normal conditions such as various steels and cast irons, but also in high-speed cutting with high heat generation. Since it exhibits excellent wear resistance over a long period of time, it can satisfactorily respond to higher performance of the cutting device, labor saving and energy saving of the cutting work, and lower cost.

Claims (2)

In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper layer is vapor-deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The lower layer has a total average layer thickness of 3 to 20 μm composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer. Consisting of a Ti compound layer,
(B) The upper layer has an average layer thickness of 2 to 15 μm, and has an alternately stacked structure in which three or more aluminum oxide layers are alternately stacked via a dividing layer,
(C) The alternately laminated aluminum oxide layers have an average layer thickness of 0.5 to 4 μm per layer, and Al ₂ O having an α-type crystal structure in an Al ₂ O ₃ substrate having a κ-type crystal structure. Having a structure in which a dispersed phase composed of _three crystal grains is dispersed and distributed;
(D) The average area ratio of the dispersed phase in the Al ₂ O ₃ substrate of the κ-type crystal structure measured in the longitudinal section of the aluminum oxide layer of the alternately laminated structure is 20 to 60 area%,
(E) The dispersion phase in the aluminum oxide layer from the surface side of the aluminum oxide layer having the alternately laminated structure to at least the first layer is measured using a field emission scanning electron microscope, and the measurement range of the polished surface parallel to the tool substrate surface The crystal grains having a hexagonal crystal lattice existing therein are irradiated with an electron beam, and the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, with respect to the normal line of the polished surface Of the measured tilt angles, and the measured tilt angles within the range of 0 to 45 degrees are divided into pitches of 0.25 degrees, and the tilt angles obtained by counting the frequencies existing in each section In the number distribution graph, the highest peak exists in the inclination angle section within the range of 30 to 45 degrees, and the total of the frequencies existing within the range of 30 to 45 degrees is 50 of the entire degrees in the inclination angle number distribution graph. % Or more Indicates the inclination angle frequency distribution graph occupied,
(F) The surface-coated cutting tool, wherein the dividing layer is composed of any one of a Ti carbide layer, a nitride layer, and a carbonitride layer having an average layer thickness of 0.1 to 1.5 μm per layer. . The surface-coated cutting tool according to claim 1,
Dispersed phase in the aluminum oxide layer from the substrate side of the aluminum oxide layer to at least a first layer of the alternate laminated structure, using a field emission scanning electron microscope, within the measuring range of the surface and parallel to the polishing surface of the tool substrate Irradiate each individual crystal grain having a hexagonal crystal lattice with an electron beam, and measure the inclination angle formed by the normal of the (0001) plane, which is the crystal plane of the crystal grain, with respect to the normal of the polished surface And, among the measured tilt angles, the measured tilt angles within a range of 45 to 90 degrees are divided into pitches of 0.25 degrees, and the tilt angle number distribution is obtained by counting the frequencies existing in each section. In the graph, the highest peak exists in the inclination angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees is 50% of the entire degrees in the inclination angle number distribution graph. Above The surface-coated cutting tool according to claim 1, characterized in that shows the inclination angle frequency distribution graph occupy.