JP2016137549A - Surface-coated cutting tool with hard coating layer exerting excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool with a hard coating layer having excellent hardness and toughness, and exerting excellent chipping resistance and defect resistance over a long term use.SOLUTION: The hard coating layer of a surface-coated cutting tool includes at least a composite nitride layer or composite carbonitride layer represented by a compositional formula: (TiAl)(CN). The average content ratio of Al, Xand that of C, Y(both Xand Yare atomic ratios) satisfy 0.60≤X≤0.95 and 0≤Y≤0.005. The crystal grain composing the composite nitride layer or composite carbonitride layer includes the crystal grain having a cubic crystal structure, and the prescribed periodic composition changes of Ti and Al comprising two short-period layers different in average Al content are formed in the crystal grain having the cubic crystal structure.SELECTED DRAWING: Figure 2

Description

  The present invention is a high-speed intermittent cutting process that involves high heat generation of alloy steel and the like, and an impact load is applied to the cutting edge, and the hard coating layer has excellent chipping resistance, so that it can be used for a long time. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance.

Conventionally, generally composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet or cubic boron nitride (hereinafter referred to as cBN) based ultra high pressure sintered body There is known a coated tool in which a Ti—Al-based composite nitride layer is formed by physical vapor deposition as a hard coating layer on the surface of a tool substrate (hereinafter collectively referred to as a tool substrate), These are known to exhibit excellent wear resistance.
However, the conventional coated tool formed with the Ti-Al composite nitride layer is relatively excellent in wear resistance, but it tends to cause abnormal wear such as chipping when used under high-speed intermittent cutting conditions. Accordingly, various proposals have been made for improving the hard coating layer.

For example, Patent Document 1 discloses a composite nitridation of Al and Ti that satisfies the composition formula (Al _x Ti _1-x ) N (wherein x is 0.40 to 0.65) on the tool base surface. When the crystal orientation analysis by EBSD is performed on the composite nitride layer made of a material layer, the area ratio of crystal grains having a crystal orientation <100> within the range of 0 to 15 degrees from the normal direction of the surface polished surface is 50. %, And when the angle between adjacent crystal grains is measured, the crystallographic arrangement in which the proportion of the small-angle grain boundaries (0 <θ ≦ 15 °) is 50% or more is made of Al and Ti. It is disclosed that by forming a hard coating layer made of a composite nitride layer by vapor deposition, the hard coating layer exhibits excellent fracture resistance even under high-speed intermittent cutting conditions.
However, since this coating tool forms a hard coating layer by physical vapor deposition, it is difficult to increase the Al content ratio x to 0.65 or more, and it is desired to further improve the cutting performance. .

From such a viewpoint, a technique for increasing the Al content ratio x to about 0.9 by forming a hard coating layer by a chemical vapor deposition method has also been proposed.
For example, Patent Document 2 discloses that the value of the Al content ratio x is 0.65 to 0.65 by performing chemical vapor deposition in a temperature range of 650 to 900 ° C. in a mixed reaction gas of TiCl ₄ , AlCl ₃ , and NH _3. Although it is described that a (Ti _1-x Al _x ) N layer of 0.95 can be formed by vapor deposition, in this document, an Al ₂ O ₃ layer is further formed on the (Ti _1-x Al _x ) N layer. Therefore, the value of the Al content ratio x is increased from 0.65 to 0.95 to form a (Ti _1-x Al _x ) N layer. It is not clear what kind of influence the cutting performance has.

Also, for example, in Patent Document 3, a TiCN layer and an Al ₂ O ₃ layer are used as an inner layer, and a cubic structure (Ti _1-x Al) including a cubic structure or a hexagonal structure is formed thereon by chemical vapor deposition. _x ) An N layer (wherein x is 0.65 to 0.90 in atomic ratio) is coated as an outer layer and a compressive stress of 100 to 1100 MPa is applied to the outer layer, whereby the heat resistance and fatigue strength of the coated tool are obtained. It has been proposed to improve.

JP 2009-56540 A Special table 2011-516722 gazette Special table 2011-513594 gazette

In recent years, there has been a strong demand for energy saving and energy saving in cutting, and along with this, cutting tends to be faster and more efficient, and the coated tool has even more chipping resistance, chipping resistance, Abnormal damage resistance such as peel resistance is required, and excellent wear resistance over long-term use is required.
However, in the coated tool described in Patent Document 1, a hard coating layer composed of a (Ti _1-x Al _x ) N layer is deposited by physical vapor deposition, and the Al content ratio x in the hard coating layer is determined. Since it is difficult to increase, for example, when subjected to high-speed intermittent cutting of alloy steel, there is a problem that it cannot be said that the wear resistance and chipping resistance are sufficient.
On the other hand, for the (Ti _1-x Al _x ) N layer deposited by the chemical vapor deposition method described in Patent Document 2, the Al content ratio x can be increased, and a cubic structure is formed. Therefore, although a hard coating layer having a predetermined hardness and excellent wear resistance can be obtained, there is a problem that the adhesion strength with the tool base is not sufficient and the toughness is inferior.
Furthermore, although the coated tool described in Patent Document 3 has a predetermined hardness and excellent wear resistance, it is inferior in toughness, so when it is used for high-speed intermittent cutting of alloy steel, etc. However, there is a problem that abnormal damage such as chipping, chipping and peeling is likely to occur, and it cannot be said that satisfactory cutting performance is exhibited.
Therefore, the present invention provides a coated tool that has excellent toughness and excellent chipping resistance and wear resistance over a long period of use even when subjected to high-speed intermittent cutting of alloy steel or the like. The purpose is to provide.

In view of the above, the present inventors have at least a composite nitride or composite carbonitride of Ti and Al (hereinafter referred to as “(Ti, Al) (C, N)” or “(Ti _1-x Al _x ) ( As a result of intensive research to improve the chipping resistance and wear resistance of a coated tool in which a hard coating layer containing a chemical layer including C _y N _1-y ) ”is formed by chemical vapor deposition. The following knowledge was obtained.

That is, the present inventors, constituting the hard layer _{(Ti 1-x Al x)} (C y N 1-y) was advanced focused intensive studies on the composition change of the _{layer, (Ti 1-x} Al _x ) When the periodic composition change of Ti and Al is formed in the crystal grains having the cubic crystal structure of the (C _y N _1-y ) layer, strain is generated in the crystal grains having the cubic crystal structure. As a result, the present inventors have found a novel finding that this strain contributes to the improvement of hardness and toughness, and as a result, the chipping resistance and fracture resistance of the hard coating layer can be improved.

Specifically, the hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and Al formed by chemical vapor deposition, and a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the average content ratio X _avg in the total amount of Ti and Al in Al and the average content ratio Y _avg in the total amount of C and N in C (where X _avg and Y _avg are either Also satisfy 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦ 0.005, respectively, and the crystal grains constituting the composite nitride or composite carbonitride layer are NaCl-type. There are those having a face-centered cubic structure, and in the crystal grains having the NaCl-type face-centered cubic structure along the normal direction of the surface of the tool base of the composite nitride or the composite carbonitride layer. _{formula: (Ti 1-x Al x} ) (C y N 1-y There is a periodic composition change of Ti and Al in the case of the crystal grains having the NaCl-type face-centered cubic structure in which the periodic composition change exists, and the composition change along the normal direction of the surface of the tool substrate. A crystal having a NaCl-type face-centered cubic structure, which is composed of a periodic layer having a period of 50 to 200 nm, and further comprising two short-period layers A and B having different average Al contents. Improves chipping resistance and chipping resistance by causing distortion in grains and improving hardness compared to conventional hard coating layers, and by improving crack growth suppression effect due to the presence of layers with different composition change periods The inventors have found that they exhibit excellent wear resistance over a long period of time.

The structure of _{(Ti 1-x Al x)} (C y N 1-y) layer, such as described above, for example, formed by the following chemical vapor deposition of periodically changing the reaction gas composition in the tool substrate surface can do.
The chemical vapor deposition reactor to be used includes a gas group A composed of NH ₃ and H ₂ and a gas group B composed of TiCl ₄ , Al (CH ₃ ) ₃ , AlCl ₃ , N ₂ , and H _2, respectively. The gas group A and the gas group B are supplied into the reactor from, for example, a constant cycle time interval so that the gas flows for a time shorter than the cycle. In the gas supply of the group A and the gas group B, a phase difference of a time shorter than the gas supply time is generated, and the reaction gas composition on the surface of the tool base is set to (i) gas group A, (b) gas group A and The mixed gas of gas group B and (c) gas group B can be changed with time. Incidentally, in the present invention, it is not necessary to introduce a long exhaust process intended for strict gas replacement. Therefore, as the gas supply method, for example, the gas supply port is rotated, the tool base is rotated, or the tool base is reciprocated to change the reaction gas composition on the tool base surface. This can be realized by changing the mixture gas in time, (b) the mixed gas of the gas group A and the gas group B, and (c) the mixed gas mainly of the gas group B.
For example, NH ₃ : 2.0 to 3.0%, H ₂ : 65 to 75 as the gas group A on the surface of the tool base, the reaction gas composition (volume% with respect to the total of the gas group A and the gas group B). %, Gas group B as AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, Al (CH ₃ ) ₃ : 0 to 0.5%, N ₂ : 0.0 ˜12.0%, H ₂ : remaining, reaction atmosphere pressure: 4.5 to 5.0 kPa, reaction atmosphere temperature: 700 to 900 ° C., supply cycle 10 to 30 seconds, gas supply time per cycle 0.5 to A phase difference of 0.40 to 0.60 seconds between the supply of the gas group A and the supply of the gas group B is set to 1.5 seconds, and a predetermined target layer thickness (Ti ₁₋ it is possible to form a _{x Al x) (C y N} 1-y) layer.

  As described above, by supplying the gas group A and the gas group B so as to have a difference in the time required to reach the tool base surface, a local compositional difference between Ti and Al is formed in the crystal grains, and as a result, In particular, even when used for high-speed intermittent cutting of alloy steel, etc., where the chipping resistance and fracture resistance are improved and the cutting edge is subjected to intermittent and impact loads, the hard coating layer can be used over a long period of time. It has been found that excellent cutting performance can be exhibited.

The present invention has been made based on the above findings,
“(1) Surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base made of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultra-high pressure sintered body In
(A) The hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm formed by a chemical vapor deposition method, and has a composition formula: (Ti _1-x Al _x ) When expressed by (C _y N _1-y ), the average content ratio X _avg and the composite nitride or composite carbonitride layer in the total amount of Ti and Al of Al in the composite nitride or composite carbonitride layer The average content ratio Y _avg (where X _avg and Y _avg are atomic ratios) in the total amount of C and N in C are 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦, respectively. 0.005 is satisfied,
(B) The composite nitride or composite carbonitride layer includes at least a composite nitride or composite carbonitride phase having a NaCl-type face-centered cubic structure,
(C) A periodic composition change of Ti and Al in the crystal grains having the NaCl type face-centered cubic structure along the normal direction of the surface of the tool base of the composite nitride or composite carbonitride layer. The crystal grains having the NaCl-type face-centered cubic structure in which the periodic composition change exists have a long-period layer in which the composition change period along the normal direction of the tool base surface is 50 to 200 nm Further, the long period layer is composed of two short period layers A layer and B layer having different average Al contents, and the period in the A layer and the B layer is 3 to 20 nm. Differences Δx ₁ and Δx ₂ between the average of the maximum value and the average of the minimum value of the Al content x in the B layer are 0.02 <Δx ₁ <0.1 and 0.02 <Δx ₂ <0.1, respectively. To a long-period layer composed of A layer and B layer Takes the difference [Delta] x ₃ average mean and minimum value of the maximum value of the Al content x is 0.05 <met [Delta] x ₃ <0.25, and wherein the [Delta] x _3> is (Δx ₁ + Δx ₂₎ A surface-coated cutting tool.
(2) For the composite nitride or composite carbonitride layer, using an electron beam backscatter diffractometer, individual crystal grains having a NaCl-type face-centered cubic structure in the composite nitride or composite carbonitride layer are used. When the crystal orientation is analyzed from the longitudinal section direction of the Ti and Al composite nitride or composite carbonitride layer, the normal line of the {100} plane which is the crystal plane of the crystal grain with respect to the normal direction of the tool base surface Measures the tilt angle formed by, and divides the tilt angle within the range of 0 to 45 degrees with respect to the normal direction among the tilt angles by pitch of 0.25 degrees, and counts the frequencies existing in each section When the inclination angle number distribution is obtained, the highest peak exists in the inclination angle section within the range of 0 to 12 degrees, and the highest peak exists in the inclination angle section within the range of 0 to 12 degrees. The total number of frequencies existing within the range of 0-12 degrees is The surface-coated cutting tool according to (1), which exhibits a ratio of 35% or more of the entire frequency in the inclination angle distribution.
(3) In a crystal grain having a NaCl-type face-centered cubic structure in which a periodic composition change of Ti and Al in the composite nitride or composite carbonitride layer exists, a periodic composition change of Ti and Al occurs. Two short-period layers A and B layers that exist along one of the equivalent crystal orientations represented by <001> of the crystal grains, and whose period along the orientation is different in average Al content The period of the long-period layer composed of the A layer and the B layer is 50 to 200 nm, and the combination of the Ti and Al of the short-period layer A layer and the B layer Al in a plane orthogonal to the orientation thereof. The surface-coated cutting tool according to (1) or (2), wherein changes in the content ratio average Xo _A and Xo _{B in} the amount are each 0.01 or less.
(4) For the composite nitride or composite carbonitride layer, the lattice constant a of the crystal grains having a NaCl type face centered cubic structure is obtained from X-ray diffraction, and the crystal grains having the NaCl type face centered cubic structure are obtained. The lattice constant a satisfies the relationship of 0.05a _TiN + 0.95a _AlN ≦ a ≦ 0.4a _TiN + 0.6a _AlN with respect to the lattice constant a _TiN of cubic _TiN and the lattice constant a _AlN of cubic AlN. The surface-coated cutting tool according to any one of (1) to (3).
(5) When the composite nitride or composite carbonitride layer is observed from the longitudinal cross-sectional direction of the layer, individual crystal grains having a NaCl-type face-centered cubic structure in the composite nitride or composite carbonitride layer There are fine crystal grains having a hexagonal crystal structure at the grain boundary portion of the columnar structure, and the area ratio of the fine crystal grains is 30 area% or less, and the average grain size R of the fine crystal grains is 0. The surface-coated cutting tool according to any one of (1) to (4), wherein the surface-coated cutting tool is 01 to 0.3 μm.
(6) Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer between the tool base and the composite nitride or composite carbonitride layer of Ti and Al The surface according to any one of (1) to (5), wherein there is a lower layer having a total average layer thickness of 0.1 to 20 μm. Coated cutting tool.
(7) The upper layer including an aluminum oxide layer having an average layer thickness of at least 1 to 25 μm exists above the composite nitride or composite carbonitride layer. (1) to (6) The surface coating cutting tool in any one.
(8) The composite nitride or the composite carbonitride layer is formed by a chemical vapor deposition method containing at least trimethylaluminum as a reactive gas component. (1) to (7) The surface coating cutting tool in any one. "
It has the characteristics.

  The present invention will be described in detail below.

Average layer thickness of the composite nitride or composite carbonitride layer constituting the hard coating layer:
In FIG. 1, the cross-sectional schematic diagram of the composite nitride or composite carbonitride layer of Ti and Al which comprises the hard coating layer of this invention is shown.
The hard coating layer of the present invention comprises at least a composite nitride or composite carbonitride layer of Ti and Al represented by a chemical vapor deposition composition formula: (Ti _1-x Al _x ) (C _y N _1-y ). Including. This composite nitride or composite carbonitride layer has high hardness and excellent wear resistance, but the effect is particularly remarkable when the average layer thickness is 1 to 20 μm. The reason is that if the average layer thickness is less than 1 μm, the layer thickness is so thin that sufficient wear resistance over a long period of use cannot be ensured. On the other hand, if the average layer thickness exceeds 20 μm, Ti and Crystal grains of the Al composite nitride or composite carbonitride layer are likely to be coarsened, and chipping is likely to occur. Therefore, the average layer thickness was set to 1 to 20 μm.

Composition of composite nitride or composite carbonitride layer constituting hard coating layer:
The composite nitride or composite carbonitride layer constituting the hard coating layer of the present invention has an average content ratio X _avg in the total amount of Ti and Al in Al and an average content ratio Y in the total amount of C and N in C Control is performed so that _avg (where X _avg and Y _avg are atomic ratios) satisfy 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦ 0.005, respectively.
The reason is that when the average content ratio X _avg of Al is less than 0.60, the composite nitride or composite carbonitride layer of Ti and Al is inferior in oxidation resistance, so that it is used for high-speed intermittent cutting of alloy steel and the like. In such a case, the wear resistance is not sufficient. On the other hand, when the average content ratio X _{avg of} Al exceeds 0.95, the precipitation amount of hexagonal crystals inferior in hardness increases and the hardness decreases, so that the wear resistance decreases. Therefore, the average content ratio X _avg of Al was determined as 0.60 ≦ X _avg ≦ 0.95.
Further, when the average content ratio Y _avg of the C component contained in the composite nitride or the composite carbonitride layer is a minute amount in the range of 0 ≦ Y _avg ≦ 0.005, the composite nitride or the composite carbonitride layer The adhesion with the tool base or the lower layer is improved, and the lubrication improves the impact during cutting. As a result, the chipping resistance and chipping resistance of the composite nitride or composite carbonitride layer are reduced. improves. On the other hand, when the average content ratio Y _{avg of the} component C is out of the range of 0 ≦ Y _avg ≦ 0.005, the toughness of the composite nitride or composite carbonitride layer is lowered, so that the chipping resistance and chipping resistance are reversed. Since it falls, it is not preferable. Therefore, the average content ratio Y _avg of C was determined as 0 ≦ Y _avg ≦ 0.005. However, the content ratio of C excludes the inevitable content ratio of C that is included without intentionally using a gas containing C as a gas raw material. Specifically, the content ratio (atomic ratio) of the C component contained in the composite nitride or composite carbonitride layer when the supply amount of Al (CH ₃ ) ₃ is 0 is determined as the inevitable C content ratio. , The inevitable C content is subtracted from the C component content (atomic ratio) contained in the composite nitride or composite carbonitride layer obtained when Al (CH ₃ ) ₃ is intentionally supplied. The value was determined as Y _avg .

Further, there is a periodic composition change of Ti and Al in the crystal grains having the NaCl-type face-centered cubic structure along the normal direction of the surface of the tool base of the composite nitride or composite carbonitride layer. In the crystal grains having the cubic structure in which a periodic composition change exists, as shown in FIG. 2, the composition change period of Ti and Al is 50 to 50 along the normal direction of the tool base surface. The long-period layer is 200 nm, and the long-period layer is composed of two short-period layers A and B having different average Al contents, and the period of each of the A and B layers is 3 to 20 nm. The differences Δx ₁ and Δx ₂ between the average of the maximum value and the average of the minimum value of the Al content x in the A layer and the B layer are 0.02 <Δx ₁ <0.1, 0.02 <Δx It met ₂ <0.1, Al in periodic layer The difference [Delta] x ₃ average mean and minimum value of the maximum value of Yuryou x is 0.05 satisfies the <[Delta] x ₃ <0.25, and, [Delta] x _3> and (Δx ₁ + Δx _2).
Here, if the period of the short-period layer is less than 3 nm, the toughness is lowered, and improvement in fracture resistance cannot be expected. On the other hand, when the period exceeds 20 nm, the crack progress suppressing effect due to the presence of different composition change periodic layers is reduced, and chipping resistance is lowered. In addition, for a long-period layer composed of two short-period layers, if the period is less than 50 nm, the effect of improving toughness by forming different composition-change period layers is small. On the other hand, if the period exceeds 200 nm, the progress of cracks cannot be suppressed, and the fracture resistance and peel resistance are reduced.
Therefore, the composition change period of Ti and Al is 3 to 20 nm for the short period layer along the normal direction of the surface of the tool base, and 50 to 200 nm for the long period layer composed of the two short period layers. .

In addition, if the difference Δx ₁ , Δx ₂ between the average of the maximum value and the average value of x in each of the A layer and the B layer constituting the short period layer is 0.02 or less, the difference in composition is small, so The suppression effect is reduced and chipping resistance is reduced. On the other hand, if Δx ₁ and Δx ₂ are 0.1 or more, the distortion of crystal grains becomes too large with respect to the thickness of the layer, lattice defects increase, and hardness decreases.
Further, if the difference Δx ₃ between the average of the maximum value and the minimum value of x in the long-period layer is 0.05 or less, the distortion of the crystal grains is small and a sufficient hardness improvement effect cannot be expected, whereas Δx ₃ Is greater than or equal to 0.25, the lattice strain of the crystal grains becomes too large and the number of lattice defects increases, so that the hardness decreases, and if Δx ₃ > (Δx ₁ + Δx ₂ ) does not hold, the short Since the periodic layer is not divided into two layers of the A layer and the B layer, the effect of suppressing crack propagation is small.
Accordingly, the short-period layer is composed of two layers of the A layer and the B layer, and the difference between the average maximum value and the average minimum value Δx ₁ and Δx ₂ of each of the A layer and the B layer is 0.02 <Δx ₁ <0.1, 0.02 <Δx ₂ <0.1, and the average of the local maximum value and the average of the local minimum values in the periodic layer composed of the A layer and the B layer of the short periodic layer The difference Δx ₃ satisfies 0.05 <Δx ₃ <0.25, and Δx ₃ > (Δx ₁ + Δx ₂ ).

{100} which is an individual crystal grain plane having a cubic structure in a Ti / Al composite nitride or composite carbonitride layer ((Ti _1-x Al _x ) (C _y N _1-y ) layer) Inclination angle number distribution on the surface:
Regarding the (Ti _1-x Al _x ) (C _y N _1-y ) layer of the present invention, the crystal orientation of individual crystal grains having a cubic structure using an electron beam backscattering diffractometer, and the longitudinal sectional direction thereof When analyzing from the above, the inclination angle formed by the normal of the {100} plane, which is the crystal plane of the crystal grain, with respect to the normal of the tool base surface (the direction perpendicular to the tool base surface on the cross-section polished surface) (FIG. 3A) , (B)) is measured, and among the tilt angles, the tilt angles within the range of 0 to 45 degrees with respect to the normal direction are divided into pitches of 0.25 degrees and exist in each section. When the frequencies to be counted are aggregated, the highest peak is present in the inclination angle section within the range of 0 to 12 degrees, and the total of the frequencies existing within the range of 0 to 12 degrees is the total of the frequencies in the inclination angle distribution. In the case of showing an inclination angle number distribution form having a ratio of 35% or more, the T The hard coating layer made of a composite nitride or composite carbonitride layer of Al and Al has a high hardness while maintaining a cubic structure, and further, the hard coating layer and the substrate have the inclination angle number distribution form as described above. Therefore, it is desirable that the crystal grains having the cubic structure of the present invention have the inclination angle number distribution form as described above.
FIG. 5 is a graph showing an example of the inclination angle number distribution obtained by measuring the crystal grains having a cubic structure according to an embodiment of the present invention by the above method.

As shown in FIG. 4, when the periodic composition change of Ti and Al is present along one of the equivalent crystal orientations represented by <001> of the cubic crystal grains, the crystal grains It is preferable that lattice defects due to the strain of the material hardly occur, and toughness and chipping resistance are improved. However, if the period of a long-period layer composed of two short-period layers A and B having different average Al contents is less than 50 nm, the toughness decreases. On the other hand, if it exceeds 200 nm, the effect of improving the hardness cannot be expected. Therefore, a length composed of two short-period layers A and B having different average Al contents present along one of the equivalent crystal orientations represented by <001> of the cubic crystal grains. The period of the periodic layer is preferably 50 to 200 nm.
Further, the composition of Ti and Al does not substantially change in the plane orthogonal to the orientation in which the periodic composition change of Ti and Al exists, and the short-period layer A and B in the orthogonal plane are not changed. The change in the content ratio average Xo in the total amount of Ti and Al in the Al layer is 0.01 or less.

Lattice constant a of cubic crystal grains in the composite carbonitride layer:
The composite carbonitride layer was subjected to an X-ray diffraction test using an X-ray diffractometer and Cu-Kα rays as a radiation source, and the lattice constant a of the cubic crystal grains was obtained. The lattice constant a is 0.000 for the lattice constant a _{TiN of the} cubic TiN (JCPDS00-038-1420): 4.24173 and the lattice constant a _{AlN of the} cubic AlN (JCPDS00-046-1200): 4.045. 05a _TiN + 0.95a _AlN ≦ a ≦ 0.4a _TiN + 0.6a When satisfying the relationship of _AlN , it exhibits higher hardness and high thermal conductivity, in addition to excellent wear resistance, Excellent thermal shock resistance. Using an X-ray diffractometer, X-ray diffraction was performed under conditions of a measurement range of 13 ° ≦ 2θ ≦ 130 °, a measurement width of 0.02 °, and a measurement time of 0.5 seconds / step. The peaks and crystal planes belonging to the composite nitride layer or composite carbonitride layer of Ti, Al, and Me having a cubic structure are identified, and for each peak, the wavelength and peak of the Cu-Kα line used The interplanar spacing of the crystal planes was calculated from the angle, and the average value of the lattice constants calculated from the interplanar spacing values was defined as the lattice constant a.

Fine hexagonal crystals present at cubic grain boundaries in a composite nitride or composite carbonitride layer of Ti and Al ((Ti _1-x Al _x ) (C _y N _1-y ) layer):
In the hard coating layer (Ti _1-x Al _x ) (C _y N _1-y ) layer of the present invention, hexagonal crystal grains can be contained in the cubic grain boundaries of the columnar structure. The presence of fine hexagonal crystals with excellent toughness at the cubic grain boundaries in the columnar structure reduces friction at the grain boundaries and improves toughness. At this time, if the area ratio of the fine crystal grains having a hexagonal structure exceeds 30 area%, the hardness is relatively lowered, and the average grain size R of the fine crystal grains having a hexagonal structure is less than 0.01 μm. If it is, the effect of improving toughness is not seen, and if it exceeds 0.3 μm, the hardness decreases and the wear resistance is impaired, so the average particle size R is preferably 0.01 to 0.3 μm. .
Incidentally, the hexagonal structure fine grains existing in the grain boundary referred to in the present invention can be identified by analyzing the electron diffraction pattern using a transmission electron microscope, and the hexagonal structure fine grains. The average particle diameter of the crystal grains can be obtained by measuring the particle diameters of the particles existing within the measurement range of 1 μm × 1 μm including the grain boundaries and calculating the average value thereof.

Lower layer and upper layer:
The composite nitride or composite carbonitride layer of the present invention alone has a sufficient effect, but one of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer. An upper layer comprising a layer or two or more Ti compound layers and having a lower layer having a total average layer thickness of 0.1 to 20 μm and / or an aluminum oxide layer having an average layer thickness of 1 to 25 μm In the case where layers are provided, it is possible to create better characteristics in combination with the effects of these layers. When providing a lower layer made of one or two or more Ti compound layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, the total average layer of the lower layer If the thickness is less than 0.1 μm, the effect of the lower layer is not sufficiently achieved. On the other hand, if it exceeds 20 μm, the crystal grains are likely to be coarsened and chipping is likely to occur. Further, if the total average layer thickness of the upper layer including the aluminum oxide layer is less than 1 μm, the effect of the upper layer is not sufficiently achieved. On the other hand, if it exceeds 25 μm, the crystal grains are likely to be coarsened and chipping is likely to occur. .

The hard coating layer including the composite nitride or composite carbonitride layer of Ti and Al of the present invention can be formed by a chemical vapor deposition method containing at least trimethylaluminum as a reaction gas component.
In FIG. 1, the schematic diagram of the cross section of the composite nitride or composite carbonitride layer of Ti and Al which comprises the hard coating layer of this invention is shown.

The present invention provides a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base, wherein the hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and Al formed by chemical vapor deposition. Including, when represented by the composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the average content ratio X _avg in the total amount of Ti and Al in Al and the total amount of C and N in C The average content ratio Y _avg (where X _avg and Y _avg are both atomic ratios) satisfy 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦ 0.005, respectively, and complex nitriding In the crystal grains constituting the product or the composite carbonitride layer, there are those having a NaCl-type face-centered cubic structure, and along the normal direction of the surface of the tool base of the composite nitride or the composite carbonitride layer. And having the NaCl type face centered cubic structure In Akiratsubu composition _{formula: (Ti 1-x Al x} ) (C y N 1-y) periodic composition variation of Ti and Al are present in the period of the change in composition is 50 to 200 nm, further The periodic layer is composed of two short-period layers A and B layers having different average Al contents, thereby causing distortion in crystal grains having a NaCl type face-centered cubic structure. Hardness is improved and toughness is improved while maintaining high wear resistance.
As a result, the chipping resistance and fracture resistance are improved, and the hard coating layer can be used for long-term use even when used for high-speed intermittent cutting of alloy steel and the like where intermittent and impact loads are applied to the cutting edge. It shows excellent cutting performance.

It is the film | membrane structure schematic diagram which represented typically the cross section of the composite nitride or composite carbonitride layer of Ti and Al which comprises the hard coating layer of this invention. A short period layer (period: 3 to 20 nm) composed of two layers of an A layer and a B layer in crystal grains of a composite nitride layer or composite carbonitride layer of Ti and Al constituting the hard coating layer of the present invention And a schematic diagram of a periodic composition change composed of a long-period layer (period: 50 to 200 nm). When the inclination angle formed by the normal of the {100} plane, which is the crystal plane of the crystal grain, with respect to the normal of the tool base surface (the direction perpendicular to the tool base surface on the cross-section polished surface) is (a) 0 degree (b) It is the schematic diagram which showed the case of 45 degree | times. In the cross section of the composite nitride layer or composite carbonitride layer of Ti and Al constituting the hard coating layer of the present invention, a crystal grain having a cubic structure in which a periodic composition change of Ti and Al exists, Ti and A periodic composition change of Al exists along one of the equivalent crystal orientations represented by <001> of the cubic crystal grains, and the composition of Ti and Al in a plane orthogonal to the orientation. It is a schematic diagram schematically showing that the change is small. It is a graph which shows an example of the inclination angle number distribution calculated | required about the crystal grain which has a cubic structure in the cross section of the composite nitride layer or composite carbonitride layer of Ti and Al which comprises the hard coating layer of this invention.

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

As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared, and these raw material powders are blended as shown in Table 1. Blended into the composition, added with wax, mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, pressed into a compact of a predetermined shape at a pressure of 98 MPa, and the compact was 1370 in a vacuum of 5 Pa. Vacuum sintered at a predetermined temperature within a range of ˜1470 ° C. for 1 hour, and after sintering, manufacture tool bases A to C made of WC-base cemented carbide with ISO standard SEEN1203AFSN insert shape, respectively. did.

In addition, as raw material powders, all TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, WC powder, Co powder having an average particle diameter of 0.5 to 2 μm. And Ni powder are prepared, 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 then pressed into a compact at a pressure of 98 MPa. The body was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base D made of TiCN-based cermet having an ISO standard SEEN1203AFSN insert shape was produced.

Next, a chemical vapor deposition apparatus is used on the surfaces of these tool bases A to D,
Formation conditions A to J shown in Table 4, that is, a gas group A composed of NH ₃ and H ₂ , a gas group B composed of TiCl ₄ , Al (CH ₃ ) ₃ , AlCl ₃ , N ₂ , H ₂ , and each method of supplying gas, the reaction gas composition (volume% to the total of the combined gas group a and gas group B), _NH 3 as a gas group _{a: 2.0~3.0%, H 2:} 65~75 %, Gas group B as AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, Al (CH ₃ ) ₃ : 0 to 0.5%, N ₂ : 0.0 ˜12.0%, H ₂ : remaining, reaction atmosphere pressure: 4.5 to 5.0 kPa, reaction atmosphere temperature: 700 to 900 ° C., supply cycle 10 to 30 seconds, gas supply time per cycle 0.5 to 1.5 seconds, phase difference between supply of gas group A and supply of gas group B 0.40 to 0.60 seconds And, a predetermined time, by thermal CVD method, to produce a present invention coated tool 15 by depositing _{(Ti 1-x Al x)} (C y N 1-y) layer shown in Table 6 .
In addition, about this invention coated tools 6-13, the lower layer and upper layer which were shown in Table 5 were formed on the formation conditions shown in Table 3.

  When the Ti and Al composite nitride or composite carbonitride layer constituting the hard coating layer of the inventive coated tool 1-15 is observed over a plurality of fields using a transmission electron microscope, a cubic structure is obtained. The area ratio in which the hexagonal structure fine crystal grains are present in the grain boundary portion of the columnar structure comprising the crystal grains is 30 area% or less, and the average grain size R of the hexagonal crystal grains is 0.01 It was confirmed to be ~ 0.3 μm. In addition, the identification of the fine-grained hexagonal crystal which exists in the grain boundary as used in the field of this invention was identified by analyzing an electron beam diffraction pattern using a transmission electron microscope. The average particle size of the fine hexagonal crystals was determined by measuring the particle size of particles present in the measurement range of 1 μm × 1 μm including the grain boundaries and calculating the total area of the fine hexagonal crystals. For the grain size, a circumscribed circle was created for the grains identified as hexagonal crystals, the radius of the circumscribed circle was determined, and the average value was taken as the grain size.

Further, for the purpose of comparison, the coated tools 1 to 4 of the present invention are formed on the surfaces of the tool bases A to D with the target layer thickness (μm) shown in Table 7 under the conditions of the comparative film forming process shown in Tables 3 and 4. 15, comparative coating tools 1 to 15 were manufactured by vapor-depositing a hard coating layer including at least a composite nitride or composite carbonitride layer of Ti and Al. At this time, by forming a hard coating layer so that the reaction gas composition on the surface of the tool base does not change with time during the film forming process of the (Ti _1-x Al _x ) (C _y N _1-y ) layer. Comparative coated tools 1-15 were produced.
In addition, similarly to this invention coated tool 6-13, about the comparison coated tool 6-13, the lower layer and upper layer which were shown in Table 5 were formed on the formation conditions shown in Table 3.

The cross sections in the direction perpendicular to the tool base of each constituent layer of the inventive coated tools 1 to 15 and comparative coated tools 1 to 15 were measured using a scanning electron microscope (magnification 5000 times), and 5 points within the observation field of view. When the average layer thickness was measured and averaged to determine the average layer thickness, the average layer thickness was substantially the same as the target layer thickness shown in Tables 6 and 7.
In addition, regarding the average Al content ratio X _avg of the composite nitride or the composite carbonitride layer, an electron beam was sampled in a sample whose surface was polished using an electron beam microanalyzer (EPMA, Electron-Probe-Micro-Analyzer). Irradiation was performed from the surface side, and an average Al content ratio X _avg of Al was obtained from an average of 10 points of the analysis result of the obtained characteristic X-rays. About average C content rate _Yavg, it calculated | required by secondary ion mass spectrometry (SIMS, Secondary-Ion-Mass-Spectroscopy). The ion beam was irradiated in the range of 70 μm × 70 μm from the sample surface side, and the concentration in the depth direction was measured for the components emitted by the sputtering action. The average C content ratio Y _avg indicates the average value in the depth direction of the composite nitride or composite carbonitride layer of Ti and Al. However, the content ratio of C excludes the inevitable content ratio of C that is included without intentionally using a gas containing C as a gas raw material. Specifically, the content ratio (atomic ratio) of the C component contained in the composite nitride or composite carbonitride layer when the supply amount of Al (CH ₃ ) ₃ is 0 is determined as the inevitable C content ratio. , The inevitable C content is subtracted from the C component content (atomic ratio) contained in the composite nitride or composite carbonitride layer obtained when Al (CH ₃ ) ₃ is intentionally supplied. The value was determined as Y _avg .

In addition, regarding the inclination angle number distribution of the hard coating layer, the cross section in the direction perpendicular to the tool base surface of the hard coating layer made of a composite nitride or composite carbonitride layer of cubic Ti and Al was used as the polished surface. In the state, it is set in a lens barrel of a field emission scanning electron microscope, and an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polished surface within the measurement range of the sectional polished surface with an irradiation current of 1 nA. Irradiate each individual crystal grain having a cubic crystal lattice, and use an electron backscatter diffraction imaging apparatus to measure the film thickness along the cross section in a direction perpendicular to the tool substrate surface and a length of 100 μm in the horizontal direction from the tool substrate surface. With respect to the normal surface of the substrate surface (direction perpendicular to the substrate surface in the cross-section polished surface) at an interval of 0.01 μm / step with respect to the hard coating layer within the measurement range of the following distance, Normal of some {100} plane Are measured, and based on the measurement results, the measured inclination angles within the range of 0 to 45 degrees are classified for each 0.25 degree pitch among the measured inclination angles. By counting the frequencies existing in the range, the presence or absence of a frequency peak existing in the range of 0 to 12 degrees was confirmed, and the ratio of the frequencies existing in the range of 0 to 12 degrees was determined. The results are also shown in Tables 6 and 7.

In addition, a transmission electron microscope was used to observe a minute region of the composite nitride or composite carbonitride layer under the condition of an acceleration voltage of 200 kV, and from the cross-sectional side using energy dispersive X-ray spectroscopy (EDS). By performing surface analysis, periodic compositional changes of Ti and Al in the composition formula: (Ti _1-x Al _x ) (C _y N _1-y ) exist in the crystal grains having the cubic structure. It was confirmed.
Further, for the crystal grains having the cubic structure in which the periodic composition change exists, the microscopic region is observed using the transmission electron microscope, and the cross section side using the energy dispersive X-ray spectroscopy (EDS) is used. From the surface analysis, the period of Ti and Al composition change was obtained, and the period of Ti and Al composition change was confirmed to be composed of two layers of short-period layer A layer and B layer having a shorter period. . Further, the difference between the average value of the local maximum value of x and the average value of the local minimum value Δx ₁ and Δx ₂ in each of the A layer and the B layer are obtained, and The average difference Δx ₃ between the average and the minimum value was also determined.
The specific measurement method is as follows.
For the crystal grains, the magnification is set so that the composition change of about 10 cycles from the density of the composition falls within the measurement range based on the result of the surface analysis, and then by EDS along the normal direction of the tool base surface. The line analysis is performed in the range of 5 periods, and the difference between the average values of the maximum and minimum values of the periodic composition change of Ti and Al is calculated as the composition change of the long period layer composed of two short period layers. It was determined as the difference Δx ₃ of the maximum value and the minimum value. In addition, the layer having the composition period exists on the maximum value side of the composition change of the long-period layer composed of two short-period layers, and the layer having the composition period exists on the minimum value side of the composition change of the long-period layer. The layer was defined as layer B, and the maximum value and the minimum value of the composition change of layer A and layer B were calculated in the range where the line analysis was performed, and the differences were determined as Δx ₁ and Δx ₂ , respectively. The results are also shown in Tables 6 and 7.

Further, by performing electron beam diffraction on the crystal grains, a periodic composition change of Ti and Al exists along one of the equivalent crystal orientations represented by <001> of the cubic crystal grains. For a sample that was confirmed to be a long-period layer composed of two short-period layers A and B with different average Al contents, the period along that direction was along that direction. Line analysis by EDS is performed in the range of 5 periods of the long period layer, and the average interval of the 5 periods of the maximum value is obtained as the period of periodic composition change of Ti and Al in the long period layer, and is orthogonal to the direction. A line analysis is performed along the direction, and the difference between the maximum value and the minimum value of the Al content ratio average X _OA and X _OB in the total amount of Ti and Al in the short period layer A and B layers is the composition of Ti and Al. Sought as a change.
The results are also shown in Tables 6 and 7.

Further, the cubic crystal grains were subjected to X-ray diffraction using Cu-Kα rays as a radiation source, and the lattice constant a of the cubic crystal grains was measured.
The results are also shown in Tables 6 and 7.

Next, the present coated tools 1 to 15 and comparative coated tools 1 to 15 are described below in a state where all the various coated tools are clamped to the tool steel cutter tip portion with a cutter diameter of 125 mm by a fixing jig. The dry high-speed face milling, which is a kind of high-speed interrupted cutting of alloy steel, and a center-cut cutting test were performed, and the flank wear width of the cutting blade was measured.
The results are shown in Table 8.

Tool substrate: Tungsten carbide-based cemented carbide, titanium carbonitride-based cermet,
Cutting test: Dry high-speed face milling, center cutting,
Work material: JIS / SCM440 block material with a width of 100 mm and a length of 400 mm,
Rotational speed: 994 min ⁻¹
Cutting speed: 390 m / min,
Cutting depth: 1.2 mm,
Single-blade feed rate: 0.1 mm / tooth,
Cutting time: 8 minutes,
(Normal cutting speed is 220 m / min),

As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared. Blended in the composition shown in Table 9, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, pressed into a green compact of a predetermined shape at a pressure of 98 MPa. In a 5 Pa vacuum, vacuum sintering is performed at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge is subjected to honing processing with an R of 0.07 mm. Tool bases α to γ made of a WC-base cemented carbide having an insert shape of CNMG12041 were manufactured.

  In addition, as raw material powder, TiCN (mass ratio TiC / TiN = 50/50) powder, NbC powder, WC powder, Co powder, and Ni powder all having an average particle diameter of 0.5 to 2 μm are prepared, These raw material powders were blended into the composition shown in Table 10, wet mixed for 24 hours with a ball mill, dried, and then pressed into a green compact at a pressure of 98 MPa. Sintered in an atmosphere at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge part is subjected to a honing process of R: 0.09 mm so that the TiCN base has an insert shape of ISO standard / CNMG120212 A cermet tool substrate δ was formed.

Next, on the surfaces of these tool bases α to γ and tool base δ, using a normal chemical vapor deposition apparatus, formation conditions A to J shown in Table 4, that is, a gas group A composed of NH ₃ and H ₂ , , TiCl ₄ , Al (CH ₃ ) ₃ , AlCl ₃ , N ₂ , H ₂ , and a method for supplying each gas, the reactive gas composition (capacity relative to the total of gas group A and gas group B) the%), _NH 3 as a gas group _{a: 2.0~3.0%, H 2:} 65~75%, AlCl 3 as gas group _{B: 0.6~0.9%, TiCl 4:} 0.2 _{~0.3%, Al (CH 3)} 3: 0~0.5%, N 2: 0.0~12.0%, H 2: remainder, reaction atmosphere pressure: 4.5～5.0KPa, reaction Atmospheric temperature: 700 to 900 ° C., supply cycle 10 to 30 seconds, gas supply per cycle During 0.5-1.5 seconds, as the phase difference 0.40 to 0.60 seconds of the feed supply and gas group B of the gas group A, a predetermined time, by thermal CVD method, shown in Table 12 (Ti the present invention coated tool 16-30 were prepared by by depositing _{1-x Al x) (C} y N 1-y) layer.
In addition, about this invention coated tools 19-28, the lower layer and upper layer which were shown in Table 11 were formed on the formation conditions shown in Table 3.

For comparison purposes, the present invention is also applied to the surfaces of the tool bases α to γ and the tool base δ by using an ordinary chemical vapor deposition apparatus under the conditions shown in Tables 3 and 4 and the target layer thicknesses shown in Table 13. Comparative coating tools 16 to 30 shown in Table 13 were produced by vapor-depositing a hard coating layer in the same manner as the coating tool.
In addition, similarly to this invention coating tool 19-28, about the comparison coating tool 19-28, the lower layer and upper layer which were shown in Table 11 were formed on the formation conditions shown in Table 3.

Moreover, the cross section of each component layer of this invention coating tool 16-30 and comparative coating tool 16-30 is measured using a scanning electron microscope (5000 times magnification), and the layer thickness of five points in an observation visual field is measured. When the average layer thickness was obtained by averaging, all showed the same average layer thickness as the target layer thickness shown in Table 12 and Table 13.
Moreover, about the hard coating layer of the said invention coating tool 16-30 and the comparison coating tool 16-28, using the method similar to the method shown in Example 1, average Al content rate _Xavg , average C content rate Y _avg , (Ti _1-x Al _x ) (C _y N _1-y ) layer having a cubic structure {100} plane normal to the tool base surface normal angle distribution Confirmation of the peak and the frequency ratio existing in the range of 0 to 10 degrees were measured.
The results are shown in Table 12 and Table 13.

Periodic composition distribution of Ti and Al exists in the cubic crystal grains of Ti and Al composite nitride or composite carbonitride constituting the hard coating layer of the inventive coated tool 16-30. Was confirmed by surface analysis using energy dispersive X-ray spectroscopy (EDS) using a transmission electron microscope (magnification: 200,000 times), and the difference Δx between the average of the maximum value of x and the average of the minimum value was obtained. .
Further, for the crystal grains having the cubic structure in which the periodic composition change exists, the microscopic region is observed using the transmission electron microscope, and the cross section side using the energy dispersive X-ray spectroscopy (EDS) is used. From the surface analysis, the period of Ti and Al composition change was obtained, and the period of Ti and Al composition change was confirmed to be composed of two layers of short-period layer A layer and B layer having a shorter period. . Further, the difference between the average of the local maximum value and the average of the local minimum value Δx ₁ and Δx ₂ in each of the A layer and the B layer is obtained, and the x in the periodic layer composed of the A layer and the B layer of the short periodic layer is obtained. The difference Δx ₃ between the average of the local maximum and the average of the local minimum was also determined.
Further, by performing electron beam diffraction on the crystal grains, a periodic composition change of Ti and Al exists along one of the equivalent crystal orientations represented by <001> of the cubic crystal grains. For a sample that was confirmed to be a long-period layer composed of two short-period layers A and B with different average Al contents, the period along that direction was along that direction. Line analysis by EDS is performed in the range of 5 periods of the long period layer, and the average interval of the 5 periods of the maximum value is obtained as the period of periodic composition change of Ti and Al in the long period layer, and is orthogonal to the direction. A line analysis is performed along the direction, and the difference between the maximum value and the minimum value of the Al content ratio average X _OA and X _OB in the total amount of Ti and Al in the short period layer A and B layers is the composition of Ti and Al. Sought as a change.
Further, the cubic crystal grains were subjected to X-ray diffraction using Cu-Kα rays as a radiation source, and the lattice constant a of the cubic crystal grains was measured.

In addition, with respect to the composite nitride or composite carbonitride layer, a columnar structure composed of individual crystal grains having a cubic structure using an electron beam backscattering diffractometer is used as a composite nitride or composite carbonitride of Ti and Al. Analysis was performed from the longitudinal cross-sectional direction of the layer, and the crystal structure, average particle diameter R, and area ratio of the fine crystal grains present in the grain boundary portion were measured.
These results are shown in Table 12 and Table 13.

Next, in the state where each of the various coated tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated tools 16 to 30 and comparative coated tools 16 to 30 are shown below. A dry high-speed intermittent cutting test for carbon steel and a wet high-speed intermittent cutting test for cast iron were performed, and the flank wear width of the cutting edge was measured for both.
Cutting condition 1:
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 390 m / min,
Cutting depth: 1.0 mm,
Feed: 0.2 mm / rev,
Cutting time: 5 minutes,
(Normal cutting speed is 220 m / min),
Cutting condition 2:
Work material: JIS / FCD700 lengthwise equal length 4 round bar with round groove,
Cutting speed: 325 m / min,
Cutting depth: 1.2 mm,
Feed: 0.2 mm / rev,
Cutting time: 5 minutes,
(Normal cutting speed is 200 m / min),
Table 14 shows the results of the cutting test.

As the raw material powder, cBN powder, TiN powder, TiCN powder, TiC powder, Al powder, and Al ₂ O ₃ powder each having an average particle diameter in the range of 0.5 to 4 μm were prepared. The mixture is blended in the composition shown in FIG. 1, wet mixed with a ball mill for 80 hours, dried, and then pressed into a green compact having a diameter of 50 mm × thickness: 1.5 mm under a pressure of 120 MPa. The green compact is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature within a range of 900 to 1300 ° C. for 60 minutes to obtain a presintered body for a cutting edge piece. In addition, Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm, superposed on a WC-based cemented carbide support piece with a normal super-high pressure Insert into the sintering machine, normal conditions A certain pressure: 4 GPa, temperature: 1200 ° C. to 1400 ° C. within a predetermined temperature, holding time: 0.8 hour sintering, and after sintering, the upper and lower surfaces are polished with a diamond grindstone, and wire discharge It is divided into predetermined dimensions by a processing apparatus, and further Co: 5 mass%, TaC: 5 mass%, WC: remaining composition and shape of JIS standard CNGA12041 (thickness: 4.76 mm × inscribed circle diameter: 12. The brazing part (corner part) of the WC-based cemented carbide insert body having a 7 mm 80 ° rhombus) has a composition consisting of Zr: 37.5%, Cu: 25%, Ti: the rest in mass%. After brazing using a brazing material of Ti-Zr-Cu alloy and having a predetermined dimension, the cutting edge is subjected to honing with a width of 0.13 mm and an angle of 25 °, followed by finishing polishing. ISO regulations CNGA120412 tool substrate b having the insert shape, were manufactured, respectively b.

Next, at least (Ti _1-x Al _x ) under the conditions shown in Tables 3 and 4 by the same method as in Example 1, using a normal chemical vapor deposition apparatus on the surface of these tool substrates A and B. The present coated tools 31 to 40 shown in Table 17 were manufactured by vapor-depositing a hard coating layer including a (C _y N _1-y ) layer with a target layer thickness.
In addition, about this invention coated tools 34-38, the lower layer and upper layer as shown in Table 16 were formed on the formation conditions shown in Table 3.

For comparison purposes, a normal chemical vapor deposition apparatus is used on the surfaces of the tool bases i and b, and at least (Ti _1-x Al _x ) (C _y N ₁ ) under the conditions shown in Tables 3 and 4. _-Y ) The comparative coating tools 31-40 shown in Table 18 were manufactured by vapor-depositing the hard coating layer containing a layer with target layer thickness.
In addition, similarly to this invention covering tool 34-38, about the comparison covering tool 34-38, the lower layer and upper layer as shown in Table 16 were formed on the formation conditions shown in Table 3.

  Moreover, the cross section of each component layer of this invention coated tool 31-40 and comparative coated tool 31-40 is measured using a scanning electron microscope (5000 times magnification), and the layer thickness of five points in an observation visual field is measured. When the average layer thickness was obtained by averaging, all showed the average layer thickness substantially the same as the target layer thickness shown in Table 17 and Table 18.

Moreover, about the hard coating layer of the said invention coating tool 31-40 and the comparative coating tool 31-38, using the method similar to the method shown in Example 1, average Al content rate _Xavg , average C content rate Y _avg , (Ti _1-x Al _x ) (C _y N _1-y ) layer having a cubic structure {100} plane normal to the tool base surface normal angle distribution The frequency ratio which exists in the range of 0 to 10 degree | times was confirmed while the peak in was confirmed.
Further, by using a method similar to the method shown in Example 1, the difference Δx between the average of the maximum value and the average of the minimum value in the periodic composition change of Ti and Al existing in the cubic crystal grains, Further, the period of the long-period layer of Ti and Al existing along one of the equivalent crystal orientations represented by Δx ₁ , Δx ₂ , Δx ₃ , <001> in the short-period layer and the long-period layer. Period and short period layer in average composition change, average X _OA between layer A and layer B, difference between maximum value and minimum value of X _OB , lattice constant a of cubic crystal grains, and individual crystal grains having cubic structure The crystal structure, average particle diameter R, and area ratio of the fine crystal grains present in the grain boundary portion of the columnar structure were measured.
The results are shown in Table 17 and Table 18.

Next, carburization shown below about this invention covering tool 31-40 and comparative covering tool 31-40 in the state where all the various covering tools were screwed to the front-end | tip part of a tool steel cutting tool with a fixing jig. A dry high-speed intermittent cutting test was performed on the quenched alloy steel, and the flank wear width of the cutting edge was measured.
Tool substrate: Cubic boron nitride-based ultra-high pressure sintered body,
Cutting test: Dry high-speed intermittent cutting of carburized and quenched alloy steel,
Work material: JIS · SCr420 (Hardness: HRC62) lengthwise equidistant four round bars with vertical grooves,
Cutting speed: 260 m / min,
Cutting depth: 0.1 mm,
Feed: 0.1 mm / rev,
Cutting time: 4 minutes
Table 19 shows the results of the cutting test.

  From the results shown in Table 8, Table 14 and Table 19, the coated tool of the present invention is within the cubic crystal grains constituting the composite nitride or composite carbonitride layer of Al and Ti constituting the hard coating layer. The presence of Ti and Al composition changes improves the toughness while maintaining high wear resistance due to the distortion of the crystal grains. Moreover, even when used for high-speed intermittent cutting where intermittent and impactful high loads act on the cutting edge, it has excellent chipping resistance and chipping resistance, resulting in excellent wear resistance over a long period of use. It is clear that it will work.

  On the other hand, for the comparative coated tool in which the composition change of Ti and Al does not exist in the cubic crystal grains constituting the composite nitride of Al and Ti or the composite carbonitride layer constituting the hard coating layer When used for high-speed intermittent cutting with high heat generation and intermittent / impact high loads acting on the cutting edge, it is clear that the life is shortened in a short time due to occurrence of chipping, chipping and the like.

  As described above, the coated tool of the present invention can be used not only for high-speed intermittent cutting of alloy steel but also as a coated tool for various work materials, and has excellent chipping resistance over a long period of use. Since it exhibits wear resistance, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting work, and the cost reduction.

Claims (8)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of any of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body,
(A) The hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm formed by a chemical vapor deposition method, and has a composition formula: (Ti _1-x Al _x ) When expressed by (C _y N _1-y ), the average content ratio X _avg and the composite nitride or composite carbonitride layer in the total amount of Ti and Al of Al in the composite nitride or composite carbonitride layer The average content ratio Y _avg (where X _avg and Y _avg are atomic ratios) in the total amount of C and N in C are 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦, respectively. 0.005 is satisfied,
(B) The composite nitride or composite carbonitride layer includes at least a composite nitride or composite carbonitride phase having a NaCl-type face-centered cubic structure,
(C) A periodic composition change of Ti and Al in the crystal grains having the NaCl type face-centered cubic structure along the normal direction of the surface of the tool base of the composite nitride or composite carbonitride layer. The crystal grains having the NaCl-type face-centered cubic structure in which the periodic composition change exists have a long-period layer in which the composition change period along the normal direction of the tool base surface is 50 to 200 nm Further, the long period layer is composed of two short period layers A layer and B layer having different average Al contents, and the period in the A layer and the B layer is 3 to 20 nm. Differences Δx ₁ and Δx ₂ between the average of the maximum value and the average of the minimum value of the Al content x in the B layer are 0.02 <Δx ₁ <0.1 and 0.02 <Δx ₂ <0.1, respectively. To a long-period layer composed of A layer and B layer Takes the difference [Delta] x ₃ average mean and minimum value of the maximum value of the Al content x is 0.05 <met [Delta] x ₃ <0.25, and wherein the [Delta] x _3> is (Δx ₁ + Δx ₂₎ A surface-coated cutting tool.   With respect to the composite nitride or composite carbonitride layer, the crystal orientation of individual crystal grains having a NaCl-type face-centered cubic structure in the composite nitride or composite carbonitride layer is determined using an electron beam backscattering diffraction apparatus. , When analyzed from the longitudinal cross-sectional direction of the composite nitride or composite carbonitride layer of Ti and Al, the inclination formed by the normal of the {100} plane, which is the crystal plane of the crystal grain, with respect to the normal direction of the tool base surface The angle is measured, and the inclination angle within the range of 0 to 45 degrees with respect to the normal direction is divided into pitches of 0.25 degrees, and the frequencies existing in each division are totaled to obtain the inclination angle. When the number distribution is obtained, the highest peak exists in the inclination angle section in the range of 0 to 12 degrees, the highest peak exists in the inclination angle section in the range of 0 to 10 degrees, and the 0 to 12 degrees. The sum of the frequencies present in the range of degrees is the slope The surface-coated cutting tool according to claim 1, characterized in that indicating the proportion of more than 35% of the total power in the frequency distribution. In the crystal grains having the NaCl-type face-centered cubic structure in which the periodic composition change of Ti and Al in the composite nitride or composite carbonitride layer exists, the periodic composition change of Ti and Al is the crystal grain. Exists along one of the equivalent crystal orientations represented by <001>, and the period along that orientation is composed of two short-period layers A and B having different average Al contents. The period of the long period layer composed of the A layer and the B layer is 50 to 200 nm, and occupies the total amount of Ti and Al of the Al of the short period layer A layer and the B layer in a plane orthogonal to the orientation. The surface-coated cutting tool according to claim 1 or 2, wherein the changes in the content average Xo _A and Xo _B are each 0.01 or less. With respect to the composite nitride or composite carbonitride layer, the lattice constant a of the crystal grains having the NaCl type face centered cubic structure is obtained from X-ray diffraction, and the lattice constant a of the crystal grains having the NaCl type face centered cubic structure is obtained. Satisfies the relationship of 0.05a _TiN + 0.95a _AlN ≦ a ≦ 0.4a _TiN + 0.6a _AlN with respect to the lattice constant a _TiN of cubic _TiN and the lattice constant a _AlN of cubic AlN. The surface-coated cutting tool according to any one of claims 1 to 3.   When the composite nitride or the composite carbonitride layer is observed from the longitudinal cross-sectional direction of the layer, a columnar shape composed of individual crystal grains having a NaCl-type face-centered cubic structure in the composite nitride or the composite carbonitride layer. There are fine crystal grains having a hexagonal crystal structure in the grain boundary portion of the structure, the area ratio of the fine crystal grains is 30 area% or less, and the average grain size R of the fine crystal grains is 0.01 to 0 5. The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool is 3 μm.   One layer of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer between the tool base and the composite nitride or composite carbonitride layer of Ti and Al The surface-coated cutting according to any one of claims 1 to 5, wherein there is a lower layer comprising a Ti compound layer composed of two or more layers and having a total average layer thickness of 0.1 to 20 µm. tool.   7. The upper layer including an aluminum oxide layer having an average layer thickness of at least 1 to 25 μm exists above the composite nitride or composite carbonitride layer. Surface coated cutting tool.   The composite nitride or composite carbonitride layer is formed by a chemical vapor deposition method containing at least trimethylaluminum as a reaction gas component, according to any one of claims 1 to 7. Surface coated cutting tool.