JP2022147773A - Surface-coated cutting tool - Google Patents

Abstract

To provide a surface-coated cutting tool having more improved defect resistance.SOLUTION: A coating layer of a surface-coated cutting tool has an average thickness in a range of 1.0 to 20.0 μm and has a layer of composite nitride or composite carbonitride of V and Al in which the average content ratio xavg of x is in a range of 0.76 to 0.95 and that ratio yavg of y is in the range of 0.000 to 0.015 when representing a composition by a composition formula: (V1-xAlx)(CyN1-y). The coating layer has crystal grains of composite nitride or composite carbonitride having an NaCl type face-centered cubic structure. In a frequency distribution in each partition of the inclination angle distribution partitioning every 0.25 degree, the inclination angles in the range of 0 to 45 degrees among those angles in which the normal direction of a {100} plane of the crystal grains forms to the normal direction of the surface of a tool base material, a highest frequency exists in any of partitions of 0 to 10 degrees. The sum of the frequency distributions of the 0-10 degrees partitions occupies 45% or more of the sum of the whole frequency of the inclination angle distribution.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool).

Conventionally, coated tools are known in which a coating layer is formed on the surface of a tool substrate such as a tungsten carbide (hereinafter referred to as WC)-based cemented carbide, and are known to exhibit excellent wear resistance. .
Various proposals have been made for improving the coating layer in order to improve the durability of the coated tool.

For example, in Patent Document 1, any of nitrides, carbonitrides, nitroxides and carbonitride oxides of (Al _1-x V _x ) (where x is 0.24 to 0.24 to 0.24 to 0.24) is formed on the surface of a tool substrate. 45) is described, and the coated tool is said to prevent chipping and chipping of the cutting edge and peeling of the coating layer, and to have good wettability.

JP 2005-271106 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a coated tool with improved chipping resistance.

A surface-coated cutting tool according to an embodiment of the present invention is
A tool base and a coating layer on the surface of the tool base,
1) The coating layer has an average layer thickness of 1.0 to 20.0 μm, and its composition is represented by the composition formula: (V _1-x Al _x )(C _y N _1-y ), It has a composite nitride layer or composite carbonitride layer of V and Al in which the average x content x _avg is 0.76 to 0.95 and the average y content y _avg is 0.000 to 0.015 ,
2) the composite nitride layer or composite carbonitride layer has crystal grains of a composite nitride or composite carbonitride having a NaCl-type face-centered cubic structure;
3) Among the inclination angles formed by the normal direction of the {100} plane of each of the crystal grains with respect to the normal direction of the surface of the tool base, the inclination angle within the range of 0 to 45 degrees is set every 0.25 degrees. In the frequency distribution in each segment of the tilt angle distribution divided into , the highest frequency exists in one of the segments of 0 to 10 degrees, and the sum of the frequency distributions of the segments of 0 to 10 degrees is the slope Occupy 45% or more of the sum of all frequencies of the angular distribution.

Furthermore, the surface-coated cutting tool according to the embodiment may satisfy one or more of the following items (1) to (7). However, (4) and (5) are not satisfied at the same time.

(1) The crystal grains are columnar crystals with an average crystal grain width of 0.1 to 2.0 μm and an average aspect ratio of 2.0 to 10.0, and have an equivalent crystal orientation represented by <001>. Along any one orientation, the content of Al in the grain has a repetitive change that takes a maximum value and a minimum value, and the difference between the average value of the maximum value and the minimum value of x Including those where Δx is 0.03 to 0.10.

(2) The crystal grains are columnar crystals having an average crystal grain width of 0.1 to 2.0 μm and an average aspect ratio of 2.0 to 10.0, and have an equivalent crystal orientation represented by <001>. Along any one orientation, the content of Al in the grain has a repetitive change that takes a maximum value and a minimum value, and the average interval of the repetitive change is 3 to 100 nm, and The change width x0 of x in the orthogonal plane is 0.01 or less.

(3) The lattice constant a of the crystal grain is 0.05a _VN +0.95a _AlN ≤ a ≤ 0.24a VN +0.05a VN +0.95a AlN ≤ a ≤ 0.24a VN +0.05a _VN +0.95a _AlN ≤ a ≤ 0.24a _VN +0. 76a Satisfy the _AlN relationship.

(4) The composite nitride or composite carbonitride layer is composed only of the crystal grains.

(5) The composite nitride or composite carbonitride layer has fine crystal grains having a hexagonal crystal structure, the area ratio of the fine crystal grains is 30% or less, and the average grain size is 0.01 to 0.30 μm.

(6) Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer between the tool substrate and the composite nitride layer or composite carbonitride layer of V and Al There is a lower layer consisting of one or more Ti compound layers and having a total average layer thickness of 0.1 to 20.0 μm.

(7) An upper layer containing at least an aluminum oxide layer is present on the composite nitride layer or the composite carbonitride layer with a total average layer thickness of 1.0 to 25.0 μm.

According to the above, it is possible to obtain a surface-coated cutting tool with improved chipping resistance.

It is a figure which showed typically the vertical cross section of the coating layer of the surface-coated cutting tool which concerns on embodiment of this invention. FIG. 3 is a diagram schematically showing changes in the Al content in crystal grains having a NaCl-type face-centered cubic structure with repeated changes in the Al content. It is a schematic diagram which shows the repetition change of the content rate of Al. 1 is a schematic perspective view of part of a gas supply pipe of an example of an apparatus for manufacturing a surface-coated cutting tool according to this embodiment; FIG. 5 is a schematic cross-sectional view of the gas supply pipe of FIG. 4; FIG. 5 is a schematic cross-sectional view showing a gas ejection port of the gas supply pipe of FIG. 4; FIG. FIG. 10 is a diagram showing the frequency distribution of the inclination angle formed by the normal direction of {100} planes of NaCl-type face-centered cubic structure crystal grains with respect to the normal direction of the surface of the tool substrate in Example 5;

The present inventors have studied a coated tool coated with a composite nitride layer or a composite carbonitride layer of V and Al (hereinafter sometimes referred to as a (VAl) (CN) layer), and found that V and Al It has been found that simply coating the composite nitride layer or composite carbonitride layer of No. 1 does not provide sufficient fracture resistance.

Therefore, as a result of repeated studies, the normal direction of the {100} plane of the (VAl) (CN) layer is oriented in a specific manner in a direction perpendicular to the surface of the tool substrate (normal direction of the surface of the tool substrate). It has been found that the chipping resistance is improved by doing so.

Below, the surface coated cutting tool which concerns on embodiment of this invention is demonstrated.
In the present specification and claims, when a numerical range is expressed as "L to M" (L and M are both numerical values), the range includes an upper limit (M) and a lower limit (L). , and the units of the upper limit (M) and the lower limit (L) are the same.

I. Coating Layer The coating layer (2) of this embodiment, as shown in FIG. 1, is present on the surface of the tool substrate (1) and comprises a (VAl)(CN) layer (3). Between the tool substrate (1) and the (VAl)(CN) layer (3) there may be a lower layer (4) and on the surface of the (VAl)(CN) layer an upper layer (5) may have
The (VAl) (CN) layer will be mainly described below.

1. (VAl)(CN) Layer (1) Average Layer Thickness The average layer thickness of the (VAl)(CN) layer is preferably 1.0 to 20.0 μm. The reason for this is that if the average layer thickness is less than 1.0 μm, the average layer thickness is too thin to ensure sufficient wear resistance over long-term use, while if the average layer thickness exceeds 20.0 μm, ( This is because the crystal grains of the VAl) (CN) layer tend to coarsen and chipping tends to occur.

(2) Composition The composition of the (VAl) (CN) layer is expressed by the composition formula: (V _1-x Al _x ) (C _y N _1-y ), the average content ratio x _avg of x is 0 .76 to 0.95, and the average content y _avg of y is preferably 0.000 to 0.015.

The reason is as follows. When x _avg is less than 0.76, the wear resistance of the (VAl)(CN) layer is not sufficient. This is because the Further, when y _avg is in the above range, the adhesion between the (VAl) (CN) layer and the tool substrate or the lower layer described later is improved, the impact during cutting is reduced, and the chipping resistance of the coating layer is improved. This is because the

The ratio of (V _1-x Al _x ) and (C _y N _1-y ) is not particularly limited, but when (V _1-x Al _x ) is 1, (C _y N _1-y ) is preferably 0.8 to 1.2. The reason for this is that if the ratio of (C _y N _1-y ) to (V _1-x Al _x ) is within the above range, the object of the present invention can be achieved more reliably.

(3) NaCl-type face-centered cubic structure The (VAl) (CN) layer preferably contains crystal grains having a NaCl-type face-centered cubic structure. That is, the area occupied by the crystal grains of the NaCl-type face-centered cubic structure in the longitudinal section (the section perpendicular to the surface of the tool substrate when treated as a flat surface, ignoring minute irregularities on the surface of the tool substrate) The ratio may be 60% or more, more preferably 80% or more, and all crystal grains (area ratio of 100%) may be NaCl-type face-centered cubic structures.

(4) Tilt distribution in the normal direction of the {100} plane The (VAl) (CN) layer has a NaCl-type face-centered cubic structure using electron backscatter analysis (EBSD: Electron Backscatter Diffraction). for grains,
[1] Measure the angle of inclination formed by the normal direction of the {100} plane of the crystal grain (the direction represented by (7) in FIG. 2) with respect to the normal direction of the surface of the tool substrate,
[2] of the tilt angles, dividing the tilt angles within the range of 0 to 45 degrees by 0.25 degrees;
[3] When calculating the tilt angle frequency distribution by aggregating the frequencies present in each section,
In the obtained tilt angle frequency distribution, there is a highest peak (maximum value of frequency) in any of the divisions in the range of 0 to 10 degrees, and the sum of the frequencies in the range of 0 to 10 degrees is 0 It is preferable that it exists at a rate of 45% or more with respect to the sum of frequencies existing in the range of to 45 degrees.
This ratio is more preferably 50% or more, and even more preferably 55% or more.
By having such an inclination angle number distribution, wear resistance is improved while toughness is maintained, and an increase in cutting resistance is suppressed by suppressing progress of wear, so chipping resistance of the coating layer is reliably improved.

In determining the distribution of the number of tilt angles, in the case of ideal random orientation, the number of tilt angles is a constant value regardless of the tilt angle formed by the normal direction of a certain crystal plane with respect to the normal direction of the surface of the tool substrate. We standardize as follows.

Here, the surface of the tool base means the average line of interface roughness between the tool base and the coating layer in the observed image of the longitudinal section. That is, when the tool substrate has a flat surface like an insert, elemental mapping using energy dispersive X-ray spectroscopy (EDS) is performed on the longitudinal section, and the obtained By performing known image processing on the elemental map, the interface between the coating layer (if there is a lower layer described later, the lower layer is used instead of the coating layer) and the tool substrate is defined, and the thus obtained coating layer and An average line is arithmetically determined for the roughness curve of the interface with the tool substrate, and this is taken as the surface of the tool substrate. The direction perpendicular to the average line is defined as the direction perpendicular to the tool substrate (layer thickness direction).

Also, even if the tool base has a curved surface like a drill, if the diameter of the tool is sufficiently large relative to the thickness of the coating layer, the interface between the coating layer and the tool base in the measurement area is Since it is substantially flat, the surface of the tool base can be determined by a similar method. That is, for example, in the case of a drill, elemental mapping using EDS is performed on a vertical cross section of the coating layer perpendicular to the axial direction, and the obtained elemental map is subjected to known image processing. The interface of the tool substrate is determined, and the mean line is arithmetically determined for the roughness curve of the interface between the coating layer and the tool substrate thus obtained, and this is used as the surface of the tool substrate. The direction perpendicular to the average line is defined as the direction perpendicular to the tool substrate (layer thickness direction).

(5) Average grain width and aspect ratio The crystal grains having a NaCl-type face-centered cubic structure in the (VAl) (CN) layer have an average crystal grain width of 0.1 to 2.0 μm and an average aspect ratio of 2.0 to 2.0 μm. Columnar crystals of 10.0 are more preferable.

The reason for this is that when the average grain width is smaller than 0.1 μm, the grain boundary increases, resulting in a decrease in plastic deformation resistance and a decrease in oxidation resistance, which easily leads to abnormal damage. This is because if the grain size is larger than 0.00 μm, the presence of coarsely grown grains tends to lower the toughness.

In addition, when the average aspect ratio of granular crystals is less than 2.0, the interfaces (grain boundaries) tend to act as fracture initiation points against the shear stress generated on the surface of the coating layer during cutting, resulting in chipping. If the average aspect ratio exceeds 10.0, fine chipping occurs on the cutting edge during cutting, and when adjacent columnar structures are chipped, the resistance to shear stress generated on the surface of the coating layer tends to decrease. This is because when the columnar structure breaks, the damage progresses at once, resulting in large chipping.

Here, a method for calculating the average grain width and the average aspect ratio will be described.
First, the grain boundaries are determined in a 50 μm observation field (longitudinal section) in the direction parallel to the tool substrate of the coating layer. As a method for determining the crystal grain boundary, the inside of the observation field plane is analyzed two-dimensionally at intervals of 0.01 μm using an electron beam backscatter diffraction apparatus, and the crystal lattice of the NaCl type face-centered cubic structure in the observation field plane Find a measurement point with If there is an orientation difference of 5 degrees or more between adjacent measurement points (hereinafter referred to as pixels) among the measurement points having the crystal lattice of the NaCl-type face-centered cubic structure, or if the adjacent pixels are NaCl-type face-centered If the crystal lattice does not have a cubic structure, the boundaries between the pixels are defined as grain boundaries.

A region surrounded by grain boundaries is defined as one crystal grain. However, a single pixel that has an orientation difference of 5 degrees or more with respect to all adjacent pixels is not treated as a crystal grain, but a crystal grain in which two or more pixels are connected is treated as a crystal grain. In this manner, grain boundary determination is performed to specify crystal grains.

Next, for a certain crystal grain i, the maximum length H _i in the direction perpendicular to the surface of the tool substrate (layer thickness direction), the grain width W _i that is the maximum length in the direction parallel to the surface of the tool substrate, and the area S _{Find i} . The aspect ratio A _i of the crystal grain i is calculated as A _i =H _i /W _i . In this way, the grain widths W ₁ to W _n (n ≥ 20) of at least 20 or more (i = 1 to 20 or more) crystal grains in the observation field are averaged by weighted area according to [Equation 1]. is the average grain width W of Similarly, the aspect ratios A ₁ to A _n (n≧20) of the crystal grains are obtained, and the average aspect ratio A of the crystal grains is obtained by taking an area-weighted average according to [Equation 2].

(6) Repetitive change in Al content [1] Maximum value and minimum value As schematically shown in FIG. , along one orientation (10) of the equivalent crystal orientations represented by <001>, with respect to the Al content (that is, also the V content), a region with a relatively high Al content It is more preferable to have a repeating change in which the maximum value is repeated at (8) and the minimum value is repeated at the region (9) where the Al content is relatively low.

Here, the content ratio of Al (that is, the content ratio of V) means, for example, the change schematically shown in FIG. In FIG. 3, each of the maximum and minimum values is the same value, and the intervals between adjacent maximum and minimum values are also the same. , the Al content ratio may alternate between maximum and minimum values, and the maximum and minimum values may or may not be the same value, and adjacent maximum and minimum values The value intervals may or may not be the same.

The difference between the average value of the maximum value and the average value of the minimum value in the Al content ratio is the difference in x (Δx) in the above-mentioned composition formula: (V _1-x Al _x ) (C _y N _1-y ) , 0.03 to 0.10. As a result, proper strain is generated in the crystal grains having the NaCl-type face-centered cubic structure, and the hardness of the coating layer is reliably improved.

That is, when Δx is less than 0.03, the aforementioned strain is small and the coating layer may not have sufficient hardness. increases, and the hardness of the coating layer may decrease.

[2] Repetition Interval It is more preferable that the average value of the repetition interval between the maximum value and the minimum value is 3 to 100 nm. The reason for this is that if the thickness is less than 3 nm, the toughness of the coating layer may decrease, while if it exceeds 100 nm, improvement in hardness of the coating layer may not be expected.

The interval between the repetition of the maximum value and the minimum value is obtained by line analysis along one of the equivalent crystal orientations represented by <001> of the crystal grain, measuring the Al content, and graphing it. It is obtained by Note that a known noise removal method (for example, moving average method) is used for graphing and analyzing.

That is, as shown in FIG. 3, a straight line m is drawn across a curve showing repeated changes in the Al content. This straight line m is drawn so that the area of the region surrounded by the curve is equal above and below the straight line m. Then, the maximum value or the minimum value of the Al content ratio is obtained for each region where the straight line m intersects the curve showing the repeated change in the Al content ratio, the interval between the two is measured, and the measured values at multiple points are calculated. By averaging, the average interval of repeated changes in the content of Al in (VAl) (CN) is obtained.

[3] A plane perpendicular to the direction of repetitive change Further, a plane perpendicular to the direction of repetitive change in the maximum and minimum values of the Al content ratio (a plane whose normal is the direction of repetitive change. In FIG. 2, In the plane whose normal is the direction of number (10), the variation width of x in the composition formula: (V _1-x Al _x ) (C _y N _1-y ) (that is, the maximum and minimum values Difference) x0 is more preferably 0.01 or less.
When this x0 is within this range, the hardness and fracture resistance of the coating layer are more reliably improved.

(7) Lattice constant of crystal grains having a NaCl-type face-centered cubic structure (VAl) (CN) layer was subjected to an X-ray diffraction test using an X-ray diffractometer using a Cu-Kα ray as a radiation source. When the _lattice constant a of the crystal grain of the face-centered cubic structure of 1200) with respect to the lattice constant _aAlN : 4.0450 Å, it is more preferable to satisfy the relationship of 0.05a _VN +0.95a _AlN = 4.050 ≤ a ≤ 0.24a _VN + 0.76a _AlN = 4.068 . When this relationship is satisfied, the (VAl)(CN) layer has better impact resistance in addition to better wear resistance by exhibiting higher hardness.

(8) Fine crystal grains having a hexagonal structure When the (VAl) (CN) layer is observed in a longitudinal section, each of the crystal grains having a NaCl-type face-centered cubic structure is a columnar crystal, and the grain boundary portion Fine crystal grains having a hexagonal crystal structure may be present in an area ratio of 30% or less.

If fine crystal grains having a hexagonal crystal structure are present in this area ratio of 30% or less, the sliding at the grain boundaries of the crystal grains having a NaCl-type face-centered cubic structure is suppressed, and the toughness of the coating layer is reliably improved. . However, when the area ratio exceeds 30%, the number of crystal grains having a NaCl-type face-centered cubic structure decreases, and the hardness of the coating layer may decrease.

Further, the average grain size of fine crystal grains having a hexagonal crystal structure is more preferably 0.01 to 0.30 μm. The reason for this is that if the average grain size is less than 0.01 μm, the suppression of grain boundary sliding described above may be insufficient, while if it exceeds 0.30 μm, strain in the coating layer increases. This is because the hardness of the coating layer may decrease.

Here, the average grain size is the diameter of a circle corresponding to the area of microcrystalline grains.

2. Lower layer The coating layer including the (VAl) (CN) layer of the present embodiment satisfactorily achieves the above object by itself. When a lower layer consisting of one or more Ti compound layers and having a total average layer thickness of 0.1 to 20.0 μm is provided, combined with the effect of this layer, the coated tool As a result, more excellent characteristics are exhibited. However, when providing a lower layer composed of one or more Ti compound layers selected from Ti carbide layer, nitride layer, carbonate layer and carbonitride layer, the total average layer thickness of the lower layer is 0. If it is less than 0.1 μm, the function of the lower layer is not sufficiently exhibited, while if it exceeds 20.0 μm, the crystal grains tend to coarsen and chipping tends to occur.

3. Upper layer In addition, when the coating layer including the (VAl) (CN) layer of the present embodiment is provided with an upper layer having a total average layer thickness of 1.0 to 25.0 μm including the aluminum oxide layer, the coated tool can be It is preferable because excellent properties are further exhibited. Here, when the total average layer thickness is less than 1.0 μm, the function of the upper layer is not sufficiently exhibited, while when it exceeds 25.0 μm, chipping tends to occur.

II. Tool Substrate (1) Material Any material can be used as long as it is a conventionally known material for tool substrates, as long as it does not hinder the achievement of the object of the present invention. For example, cemented carbide (WC-based cemented carbide, containing Co in addition to WC, and further containing carbonitrides such as Ti, Ta, Nb, etc.), cermet (TiC, TiN, TiCN, etc. as a main component), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), or cBN sintered body.

(2) Shape The shape of the tool base is not particularly limited as long as it is a shape used as a cutting tool, examples of which include the shape of an insert and the shape of a drill.

III. Manufacturing Method The manufacturing method of the (VAl)(CN) layer of the present embodiment includes, for example, gas group A consisting of NH ₃ gas and H ₂ gas and gas group B consisting of VCl ₄ , AlCl ₃ , N ₂ and H ₂ . can be performed by a CVD method.

Here, the gas group A and the gas group B are separated and supplied to immediately before the object to be deposited in the space in the reaction vessel of the thermal CVD apparatus. Allow group B to mix and react. This is effective for uniformly supplying gas species having high reactivity with each other over the film forming region to uniformly form a film. Detailed technical content is disclosed, for example, in Japanese Patent No. 6511798.

The film forming apparatus described in the publication has gas supply pipes shown in FIGS. 4 to 6, and the structure thereof will be explained.
As shown in FIGS. 4 and 5, a gas supply pipe (11), which is a cylindrical pipe that rotates about its center (13) at a predetermined rotational speed, is separated by a partition member (12) extending along its axial direction. , the inside of which is divided into two halves, and has a gas group A distribution section (14) and a gas group B distribution section (15).

As shown in FIG. 4, the gas supply pipe (11) has a gas group A jet port (16) and a gas group B jet port (17) that constitute a jet port pair (20) positioned at approximately the same height. A plurality of them are provided along the height direction.

The gas group A ejection port (16) and the gas group B ejection port (17) shown in FIG. 5 belong to the same ejection port pair (20). The angle between (18) and the center (19) of the opening end on the outer peripheral side of the gas group B ejection port (17) is α.

Further, as shown in FIG. 6, the relative angle around the axis between the source gas group A jet ports 16 in two jet port pairs (20) adjacent in the height direction (axial direction) is β1, and the height direction (axis direction) is β1. β2 of the relative angle around the axis between the source gas group B ejection ports 17 in the two ejection port pairs (20) adjacent to each other in the direction ). The relative angles around the axis of the gas group A ejection port (16) and the gas group B ejection port (17) adjacent to each other in the height direction (axial direction) are γ1 and γ2, respectively.

IV. Measurement Method (1) Average Layer Thickness After determining the surface of the tool substrate as described above, measurements are taken on a plurality of analytical lines (eg, 5 lines) along a direction perpendicular to the surface of the tool substrate. The average layer thickness of the (VAl) (CN) layer is defined as the boundary with the adjacent layer when Al atoms appear and the content ratio is 1 atomic %, the layer thickness is obtained for each analysis line, and the average is calculated. average layer thickness.

(2) Composition The composition of the (VAl) (CN) layer is obtained as follows.
For the average Al content x _avg , an electron beam microanalyzer (EPMA: Electron Probe Micro Analyser) is used to irradiate an electron beam from the sample surface side on a sample whose surface has been polished, and analysis of the obtained characteristic X-rays. The average Al content x _avg is obtained from the 10-point average of the results.

The average C content y _avg was determined by secondary ion mass spectroscopy (SIMS). An ion beam is irradiated in a range of 70 μm×70 μm from the sample surface side, and the concentration in the depth direction is measured for the components emitted by the sputtering action.

(3) Crystal grains having a NaCl-type face-centered cubic structure By electron beam diffraction using a transmission electron microscope (TEM), the crystal structure of the (VAl) (CN) layer was identified and confirmed to be a NaCl-type face-centered cubic structure. Check and find the area ratio.

(4) Tilt angle number distribution For the tilt angle number distribution of the (VAl) and (CN) layers, a field-emission scanning electron microscope (FE-SEM) was observed with the vertical cross section as a polished surface. and an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees on the polished surface with an irradiation current of 1 nA, and a NaCl-type face-centered cubic structure existing within the measurement range of the cross-sectional polished surface. The crystal grains are individually irradiated.

Using the EBSD method, 0.01 μm/step of the coating layer within a measurement range of 50 μm in length in the horizontal direction to the surface of the tool substrate and to the distance of the layer thickness along the cross section in the direction perpendicular to the surface of the tool substrate. In the interval, the inclination formed by the normal of the {100} plane, which is the crystal plane of the (VAl) (CN) layer, with respect to the normal of the surface of the tool substrate (the direction perpendicular to the surface of the tool substrate in the polishing surface) Measure angles.

Then, based on the measurement results, the measured tilt angles within the range of 0 to 45 degrees are divided into intervals of 0.25 degrees, and the frequencies present in each division are counted. By doing so, the existence of a frequency peak existing within the range of 0 to 10 degrees (maximum frequency) is confirmed, and the ratio of frequencies existing within the range of 0 to 10 degrees is obtained.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples. That is, an insert cutting tool using a WC-based cemented carbide as the tool base is given as an example, but the material of the tool base may be the one described above, and the shape thereof may be the shape of a drill or the like as described above.

1. Manufacture of Tool Substrate As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, each having an average particle size of 1 to 3 μm, were prepared. Further, wax was added and mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, and then press-molded into a compact having a predetermined shape at a pressure of 98 MPa.

After that, this green compact is vacuum sintered under the condition of holding for 1 hour at a predetermined temperature in the range of 1370 to 1470° C. in a vacuum of 5 Pa, and after sintering, the insert shape of Mitsubishi Materials Corporation LOGU1207040PNER-M is made. Tool substrates A to C each made of WC-based cemented carbide were produced.

2. Film formation A (VAl) (CN) layer was formed on the surfaces of tool substrates A to C using a CVD apparatus to obtain Examples 1 to 10 shown in Tables 5 and 6. The film formation conditions were as shown in Table 2, and were generally as follows.

Reaction gas composition (content ratio of gas components is volume %, with the total of gas group A and gas group B being 100 volume %):
Gas Group A NH ₃ : 3.5-4.0%, H ₂ : 55-60%
Gas group B: AlCl ₃ : 0.6 to 0.9%, VCl ₄ : 0.2 to 0.3%,
Al(CH ₃ ) ₃ : 0.0 to 0.5%, N ₂ : 0.0 to 12.0%,
H ₂ : Residual reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-850°C

Here, gas group A and gas group B were respectively supplied as source gas A and source gas B of the CVD apparatus described in Japanese Patent No. 6,511,798. The rotation speed of the gas supply pipe and the ejection hole angle of the gas supply pipe were as follows.
Rotation speed of gas supply pipe: 5 to 20 rpm
Jet hole angle of gas supply pipe:
α: 180°
β1 and β2: 155°
γ1 and γ2: 25°

For Examples 4 to 10, the lower layer and/or the upper layer shown in Table 4 were formed under the conditions shown in Table 3.

For comparison, a (VAl) (CN) layer was formed on the surfaces of the tool substrates A to C under the film formation conditions shown in Table 2, and Comparative Examples 1 to 10 shown in Tables 5 and 6 were obtained.
In the comparative example process, the raw material gas was not separated into two systems and was supplied from one gas supply pipe into the reaction vessel of the thermal CVD apparatus. Therefore, a gas supply pipe was used in which there was no distinction between the gas group A ejection port (16) and the gas group B ejection port (17) and the ejection port pair (20) did not exist.
For Comparative Examples 4 to 10, the lower layer and/or the upper layer shown in Table 4 were formed under the conditions shown in Table 3.

For Examples 1 to 10 and Comparative Examples 1 to 10, the average Al content x _avg and the average C content y _avg were calculated using the method described above. In addition, in each tilt angle number distribution formed by the normal of the {100} plane with respect to the normal direction of the surface of the tool base, confirm whether the maximum number of tilt angles exists in the division within 0 to 10 degrees. At the same time, the ratio of the angles of tilt existing within the range of 0 to 10 degrees was obtained. Furthermore, the presence or absence of repeated changes in the Al content ratio along the equivalent orientation represented by <001> of the Al composition change, the difference between the average of the maximum value and the average of the minimum values of the Al content ratio, and the repetition of the average Measurements were also made on the spacing and further on the change in the Al content in the plane perpendicular to the orientation.

In addition, the proportion of crystal grains having a NaCl-type face-centered cubic structure, the lattice constants of TiN and AlN having a NaCl-type face-centered cubic structure, and the grain boundaries of columnar crystals having a NaCl-type face-centered cubic structure The area ratio of crystal grains with fine grain sizes was measured.
In addition, the average layer thickness was obtained by observing the longitudinal section of each constituent layer using a scanning electron microscope (magnification of 5000 times), measuring the layer thickness at five points within the observation field, and averaging them. .

These results are summarized in Tables 5 and 6. 7 shows the frequency distribution of the tilt angles formed by the normal direction of the {100} planes of the crystal grains of the NaCl-type face-centered cubic structure with respect to the normal direction of the surface of the tool substrate in Example 5. As shown in FIG.

Subsequently, in each of Examples 1 to 10 and Comparative Examples 1 to 10, a wet face milling test of alloy steel SCM440 was performed in a state where the tip of a tool steel cutter with a cutter diameter of 32 mm was clamped with a fixture. Then, the flank wear width of the cutting edge was measured.

Cutting test: Wet face milling Work material: JIS SCM440 width Cutting speed: 200 m/min
Notch ap: 6.0mm
Notch ae: 20mm
Feed amount per blade: 0.1 mm/blade cutting time: 80 minutes

Table 7 shows the results of the cutting test. In Comparative Examples 1 to 10, since the end of life was reached due to chipping of the cutting edge, the time until the end of life is shown.

As is clear from the results shown in Table 7, none of the examples had chipping at the cutting edge, improved chipping resistance, and exhibited excellent cutting performance over a long period of time.
On the other hand, in Comparative Examples 1 to 10, chipping of the cutting edge occurred and the service life was reached in a short time.

1 Tool substrate 2 Coating layer 3 (VAl) (CN) layer 4 Lower layer 5 Upper layer 6 (VAl) (CN) layer NaCl type Crystal grains having a face-centered cubic structure 7 (VAl) (CN) layer NaCl type Equivalent crystal represented by <001> Direction 11 Gas supply pipe 12 Partition member 13 Center of gas supply pipe 14 Gas group A circulation part 15 Gas group B circulation part 16 Gas group A ejection port 17 Gas group B ejection port 18 Gas group A ejection port at the outer peripheral side opening end Center 19 Center 20 of the opening end on the outer peripheral side of gas group B ejection port Pair α Angle β1 Angle β2 Angle γ1 Angle γ2 Angle

Claims (8)

A surface-coated cutting tool having a tool substrate and a coating layer on the surface of the tool substrate,
1) The coating layer has an average layer thickness of 1.0 to 20.0 μm, and its composition is represented by the composition formula: (V _1-x Al _x )(C _y N _1-y ), It has a composite nitride layer or composite carbonitride layer of V and Al in which the average x content x _avg is 0.76 to 0.95 and the average y content y _avg is 0.000 to 0.015 ,
2) the composite nitride layer or composite carbonitride layer has crystal grains of a composite nitride or composite carbonitride having a NaCl-type face-centered cubic structure;
3) Among the inclination angles formed by the normal direction of the {100} plane of each of the crystal grains with respect to the normal direction of the surface of the tool base, the inclination angle within the range of 0 to 45 degrees is set every 0.25 degrees. In the frequency distribution in each segment of the tilt angle distribution divided into , the highest frequency exists in one of the segments of 0 to 10 degrees, and the sum of the frequency distributions of the segments of 0 to 10 degrees is the slope accounting for 45% or more of the sum of all frequencies of the angular distribution;
A surface-coated cutting tool characterized by: The crystal grains are columnar crystals having an average crystal grain width of 0.1 to 2.0 μm and an average aspect ratio of 2.0 to 10.0. Along one orientation, the Al content ratio in the grain has a repetitive change that takes a maximum value and a minimum value, and the difference Δx between the average value of the maximum value and the minimum value of x is 0 A surface coated cutting tool according to claim 1, comprising .03 to 0.10. The crystal grains are columnar crystals having an average crystal grain width of 0.1 to 2.0 μm and an average aspect ratio of 2.0 to 10.0. A plane perpendicular to the orientation, which has a repetitive change in which the Al content ratio in the grain takes a maximum value and a minimum value along one orientation, and the average interval of the repetitive change is 3 to 100 nm. 3. The surface-coated cutting tool according to claim 1, wherein the change width x0 of said x within is 0.01 or less. The lattice constant a of the crystal grain is 0.05a _VN + 0.95a _AlN ≤ a ≤ 0.24a _VN + 0.76a _AlN with respect to the lattice constant a _VN of cubic VN and the lattice constant a _AlN of cubic AlN. The surface-coated cutting tool according to any one of claims 1 to 3, which satisfies the relationship of The surface-coated cutting tool according to any one of claims 1 to 4, wherein the composite nitride or composite carbonitride layer consists only of the crystal grains. The composite nitride or composite carbonitride layer has fine crystal grains having a hexagonal crystal structure, the area ratio of the fine crystal grains is 30% or less, and the average grain size is 0.01. The surface-coated cutting tool according to any one of claims 1 to 4, characterized in that the thickness is up to 0.30 µm. one of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer between the tool base and the composite nitride layer or composite carbonitride layer of V and Al The surface coated cutting according to any one of claims 1 to 6, characterized in that there is a lower layer consisting of a layer or two or more Ti compound layers and having a total average layer thickness of 0.1 to 20.0 μm. tool. An upper layer containing at least an aluminum oxide layer exists on the composite nitride layer or the composite carbonitride layer with a total average layer thickness of 1.0 to 25.0 μm. A surface-coated cutting tool according to any one of the above.

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