JP4888710B2 - Surface coated cutting tool with excellent chipping resistance due to hard coating layer - Google Patents

Description

  The present invention provides a hard coating even when cutting various materials such as steel and cast iron under high-speed heavy cutting conditions with high heat generation and intermittent and impactful loads on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping resistance.

Conventionally, a hard surface is formed on the surface of a base body (hereinafter collectively referred to as a tool base body) composed of a tungsten carbide (hereinafter referred to as WC) base cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) base cermet. As a coating layer,
(A) The lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO). And a Ti compound layer composed of one or more of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) The upper layer has a chemical vapor-deposited Al and Zr composite oxide structure, and the content ratio of the Zr component is 0.003 by atomic ratio (Zr / (Al + Zr)) in the total amount with the Al component. 0.05, and a composite oxide layer of Al and Zr (hereinafter referred to as “conventional (Al, Zr) ₂ O ₃ layer”) having a Σ3 distribution ratio of 60 to 80%,
It is well known that a coated tool formed by vapor deposition (hereinafter referred to as a conventional coated tool) is used for cutting various steels, cast irons and the like.

The conventional (Al, Zr) ₂ O ₃ layer is
For example, in a normal chemical vapor deposition system,
Reaction gas composition: by _{volume%, AlCl 3: 2.3~4%,} ZrCl 4: 0.02~0.13%, CO 2: 1~5%, HCl: 1.5~3%, H 2 S : 0.05~0.2%, H _2: remainder,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
On the surface of the Ti compound layer as the lower layer under the conditions
A composite oxide nucleus of Al and Zr satisfying the composition formula: (Al _1-Y Zr _Y ) ₂ O ₃ (wherein Y: 0.003 to 0.05 in atomic ratio) is formed, and subsequently, The hard coating is applied in a state in which the heating atmosphere is changed to a hydrogen atmosphere of pressure: 3 to 13 kPa and the composite oxide core thin film of Al and Zr is heated under the condition that the heating atmosphere temperature is raised to 1100 to 1200 ° C. As the upper layer of the layer,
Reaction gas composition: by _{volume%, AlCl 3: 2.3~4%,} ZrCl 4: 0.02~0.13%, CO 2: 3~8%, HCl: 1.5~3%, H 2 S : 0.05~0.2%, H _2: remainder,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
A composite oxide layer of Al and Zr satisfying the same compositional formula: (Al _{1 -Y} Zr _Y ) ₂ O ₃ (wherein the atomic ratio is Y: 0.003 to 0.05) It is also known to be obtained by doing.

Further, in the conventional coated tool, the TiCN layer of the Ti compound layer constituting the lower layer of the hard coating layer is formed as an organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus for the purpose of improving the strength of the layer itself. It is also known to form a vertically elongated crystal structure by chemical vapor deposition at a medium temperature range of 700 to 950 ° C. using a mixed gas containing benzene.
JP 2006-289557 A Japanese Patent Laid-Open No. 6-8010

In recent years, the performance of cutting equipment has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and along with this, cutting tends to be faster. For tools, there is no problem when this is used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron, but this is accompanied by high heat generation and high load on the cutting edge. When used for high-speed heavy cutting, since the grain boundary strength in the (Al, Zr) ₂ O ₃ layer constituting the upper layer of the hard coating layer is not sufficient, chipping is likely to occur due to cracks generated therefrom. Therefore, it is the present situation that the service life is reached in a relatively short time due to this.

In view of the above, the present inventors pay attention to the coated tool in which the above-described conventional (Al, Zr) ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and particularly in high-speed heavy cutting. As a result of research to further improve the chipping resistance of the hard coating layer,
(A) The conventional (Al, Zr) ₂ O ₃ layer as the upper layer constituting the hard coating layer of the conventional coated tool has excellent high-temperature hardness and predetermined high-temperature strength. Since the grain boundary strength of the crystal grains made of the product is not sufficient, it does not show satisfactory chipping resistance in high-speed heavy cutting, but the usual chemicals are formed on the Ti compound layer which is the lower layer of the vapor-deposited hard coating layer. In vapor deposition equipment,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
ZrCl _4: 0.2~0.5%,
CO _2: 4~8%,
HCl: 3-5%,
H ₂ S: 0.25~0.6%,
Ar: 5 to 50%
H ₂ : Remaining
(B) Reaction atmosphere temperature; 980-1100 ° C.
(C) Reaction atmosphere pressure; 5-10 kPa,
When an upper layer made of a composite oxide layer of Al and Zr (hereinafter referred to as “modified (Al, Zr) ₂ O ₃ layer”) having an average layer thickness of 2 to 15 μm is formed under the conditions of The upper layer formed under the conditions satisfies X = 0.0001 to 0.002 when the content ratio of the Zr component in the total amount with the Al component in the layer is X (however, the atomic ratio). Furthermore, using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam to form a crystal grain composed of a hexagonal crystal lattice. The angle at which each normal line of the crystal plane intersects the normal line of the surface-polished surface is measured, and from this measurement result, the (0001) plane and the {10-10} plane that are the crystal planes of the crystal grains are selected, and Selected (0001) plane and {10-10 When the angles at which the normals of the (0001) planes and the normals of the {10-10} planes intersect each other at the interface between adjacent crystal grains (grain interface unit) are obtained, A crystal grain interface unit (hereinafter referred to as a small-angle grain interface) in which the normals of the planes and the normal lines of the {10-10} planes intersect each other occupies a ratio of 35% or more of the total crystal grain interface units. The crystal grain interface arrangement is shown (hereinafter, such a crystal grain interface arrangement is referred to as a crystal grain interface arrangement with a small-angle grain interface ratio of 35% or more).

(B) Since the upper layer composed of the modified (Al, Zr) ₂ O ₃ layer formed by vapor deposition under the chemical vapor deposition condition of (a) above has an increased grain boundary strength of each crystal grain, In addition to the excellent high-temperature hardness of the conventional (Al, Zr) ₂ O ₃ layer, the coating tool provided with this as the upper layer of the hard coating layer has a further excellent high-temperature strength. Even in cutting under severe conditions such as high-speed heavy cutting with high heat generation and high load, the hard coating layer has improved chipping resistance compared to conventional coated tools, and it has also been superior over a long period of time. Demonstrate wear resistance.
The research results shown in (a) and (b) have been obtained.

This invention was made based on the above research results,
“On the surface of the tool base made of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) The lower layer is one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer having an overall average layer thickness of 3 to 20 μm. A Ti compound layer comprising:
(B) The upper layer has an average layer thickness of 2 to 15 μm, is composed of a chemical vapor deposited Al and Zr composite oxide layer, and uses a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. The angle at which each normal of the constituent crystal planes of the crystal grains composed of hexagonal crystal lattices intersects the normal of the polished surface is irradiated with an electron beam to each crystal grain existing within the measurement range of the polished surface. From this measurement result, the (0001) plane and the {10-10} plane which are the constituent crystal planes of the crystal grains are selected, and the selected (0001) plane and {10-10} plane are adjacent to each other. When the angles at which the normals of the (0001) planes and the normals of the {10-10} planes intersect each other at the interface between crystal grains (grain interface unit) are calculated, And the {10-10} plane Grain interface arrangement in which the crystal grain interface unit (small angle grain interface) where the angle between the lines intersects 15 degrees or less accounts for 35% or more of the total grain interface unit (grain interface arrangement with a small angle grain interface ratio of 35% or more) In addition, the content ratio of the Zr component in the composite oxide layer of Al and Zr is an atomic ratio (Zr / (Al + Zr)) in the total amount with the Al component and is 0.0001 to 0.002. A complex oxide layer of Zr,
A surface-coated cutting tool (coated tool) which is formed by vapor-depositing the hard coating layer composed of (a) and (b) and exhibits excellent chipping resistance. "
It has the characteristics.

Below, the constituent layer of the hard coating layer of the coated tool of this invention is demonstrated in detail.
(A) Lower layer (Ti compound layer)
Ti compound layer composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer exists as a lower layer of the hard coating layer, In addition to contributing to improving the high temperature strength of the hard coating layer due to its excellent high temperature strength, it firmly adheres to both the tool base and the modified (Al, Zr) ₂ O ₃ layer, and thus the tool of the hard coating layer It has the effect of improving the bonding strength to the substrate. However, if the average layer thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, if the average layer thickness exceeds 20 μm, it is particularly high speed with high heat generation. Intermittent cutting tends to cause thermoplastic deformation, which causes uneven wear, so the average layer thickness was determined to be 3 to 20 μm.

(B) Upper layer (modified (Al, Zr) ₂ O ₃ layer)
The Al component, which is a component of the chemical vapor deposited Al and Zr composite oxide layer, improves the high-temperature hardness and grain boundary strength of the layer, and the Zr component contains a trace amount (total amount of Al in the layer). Zr / (Al + Zr) is contained in a ratio of 0.0001 to 0.002 (however, atomic ratio)), so that the high temperature strength of the upper layer (modified (Al, Zr) ₂ O ₃ layer) is increased. Although it contributes to improvement, when the content ratio of the Zr component is less than 0.0001, the above effect cannot be expected. On the other hand, when the content ratio of the Zr component exceeds 0.002, the content of Al and Zr Since ZrO ₂ particles are precipitated in the composite oxide layer and the grain boundary strength of the composite oxide of Al and Zr is lowered, the content ratio of the Zr component in the total amount with the Al component (Zr / (Al + Zr) ratio) Value) was defined as 0.0001 to 0.002 (however, atomic ratio)) .

In order to form a modified (Al, Zr) ₂ O ₃ layer by chemical vapor deposition in which the value of the ratio of Zr / (Al + Zr) is 0.0001 to 0.002 (however, the atomic ratio), the reaction during vapor deposition It is necessary to adjust each chemical vapor deposition condition of gas composition, reaction atmosphere temperature, and reaction atmosphere pressure as follows.
That is,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
ZrCl _4: 0.2~0.5%,
CO _2: 4~8%,
HCl: 3-5%,
H ₂ S: 0.25~0.6%,
Ar: 5 to 50%
H ₂ : Remaining
(B) Reaction atmosphere temperature; 980-1100 ° C.
(C) Reaction atmosphere pressure; 5-10 kPa,
When a deposited layer having an average layer thickness of 2 to 15 μm is formed under the above conditions, a modified (Al, Zr) ₂ O in which the value of the ratio of Zr / (Al + Zr) is 0.0001 to 0.002 in atomic ratio _Three layers can be formed.

The modified (Al, Zr) ₂ O ₃ layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. The angle at which each normal line of the constituent crystal plane of the crystal grain composed of hexagonal crystal lattice intersects the normal line of the surface polished surface is measured (FIG. 1), and from this measurement result, it is the constituent crystal plane of the crystal grain. The (0001) plane and the {10-10} plane are selected, and in the selected (0001) plane and {10-10} plane, the (0001) plane at the interface between adjacent crystal grains (crystal grain interface unit), respectively. The angle at which the normals of the {0001} plane and the normals of the {10-10} plane intersect is 15 degrees. Grain boundary below (Fig. 2) Since the unit indicates the grain boundaries sequences account for more than 35% of the total grain surface unit (angle grain surface ratio of 35% or more grain boundaries sequence), formed by chemical vapor deposition of the Al ₂ O ₃ layer In this case, a small amount (0.2 to 0.5%) of ZrCl ₄ is added to the reaction gas, and Ar is relatively deposited at a reaction atmosphere temperature of 980 to 1100 ° C. The interface ratio increases, the grain boundary strength of the crystal grains composed of hexagonal crystal lattices in the composite oxide phase of Al and Zr is strengthened, and as a result, under severe cutting conditions such as high speed heavy cutting. However, the generation of cracks in the modified (Al, Zr) ₂ O ₃ layer constituting the upper layer of the hard coating layer is suppressed, and even if cracks occur, the growth and propagation of cracks is prevented. Prevented and hard coating layer Improvement of chipping resistance can be improved.
However, if the thickness of the upper layer is less than 2 μm, the excellent characteristics of the upper layer cannot be fully exhibited, while if the thickness of the upper layer exceeds 15 μm, chipping tends to occur. The average layer thickness of the upper layer was set to 2 to 15 μm.

On the other hand, in the conventional coated tool in which the upper layer of the hard coating layer is a conventional (Al, Zr) ₂ O ₃ layer, the surface of the upper layer is measured using a field emission scanning electron microscope and an electron backscatter diffraction image device. Irradiate each crystal grain within the measurement range of the polished surface with an electron beam, and measure the angle at which each normal of the constituent crystal planes of the crystal grains composed of hexagonal crystal lattices intersects the normal of the surface polished surface Then, from this measurement result, the (0001) plane and the {10-10} plane, which are the constituent crystal planes of the crystal grains, are selected, and further, the adjacent crystals on the selected (0001) plane and {10-10} plane, respectively. When the angle at which the normals of the (0001) planes and the normals of the {10-10} planes intersect each other at the grain interface (grain interface unit) is determined, the small-angle grain interface ratio is only less than 35%. for, grain boundary strength of the crystal grains in the composite oxide layer of l and Zr is weak, as a result, the severe cutting conditions of high-speed intermittent cutting work, the upper layer (conventional (Al, Zr) ₂ O ₃ layer) to crack Since it is easy to generate and the growth and propagation of the generated crack cannot be suppressed, the chipping resistance of the hard coating layer of the conventional coated tool is inferior.

As described above, the coated tool according to the present invention includes a field emission scanning electron microscope and an electron backside of the modified composite oxide layer of Al and Zr (modified (Al, Zr) ₂ O ₃ layer) constituting the upper layer. Using a scattering diffraction image apparatus, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the respective normals of the constituent crystal planes of the crystal grains comprising the hexagonal crystal lattice are (FIG. 1), and from this measurement result, the (0001) plane and the {10-10} plane which are the constituent crystal planes of the crystal grains are selected, and the selected (0001) plane and In the {10-10} plane, when the angles at which the normal lines of the (0001) plane and the normal lines of the {10-10} plane intersect each other at the interface between adjacent crystal grains (grain interface unit) are obtained. , The method of the (0001) plane Grain interface arrangement (small-angle grain interface) in which the crystal grain interface units having an angle of 15 ° or less (FIG. 2) intersecting each other and the normal lines of the {10-10} plane account for a proportion of 35% or more of the total crystal grain interface units In addition to the excellent high-temperature hardness of the conventional (Al, Zr) ₂ O ₃ layer of the conventional coated tool, it shows a much higher high-temperature strength, lubricity, and heat resistance. Even when various steels and cast irons are used under high-speed heavy cutting conditions where high heat generation and high load are applied, the hard coating layer exhibits excellent chipping resistance and further increases the service life. Life extension is possible.

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

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 2 to 4 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By processing, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG 160412 were produced.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to f made of TiCN-based cermet having standard / CNMG 160412 chip shapes were formed.

Next, each of the tool bases A to F and the tool bases a to f was charged into a normal chemical vapor deposition apparatus. First, Table 3 (l-TiCN in Table 3 is disclosed in JP-A-6-8010). The combinations shown in Table 5 under the conditions shown in Table 5 are the conditions for forming the TiCN layer having the vertically grown crystal structure described, and the other conditions for forming the normal granular crystal structure. And Ti compound layer was vapor-deposited as a lower layer of a hard coating layer with target layer thickness.
Next, according to the deposition conditions shown in Table 4, the coated tool of the present invention is formed by vapor-depositing the target layer thickness modified (Al, Zr) ₂ O ₃ layer shown in Table 5 as the upper layer of the hard coating layer. 1 to 13 were produced.

For comparison purposes, a comparative coating tool is formed by forming a conventional (Al, Zr) ₂ O ₃ layer with the target layer thickness shown in Table 6 under the conditions shown in Table 4 as the upper layer of the hard coating layer. 1 to 13 were produced.

Subsequently, the modified (Al, Zr) ₂ O ₃ layer and the conventional (Al, Zr) ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present invention coated tools 1 to 13 and comparative coated tools 1 to 13 described above. Was examined using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus.
That is, for the modified (Al, Zr) ₂ O ₃ layer of the present invention coated tools 1 to 13 and the conventional (Al, Zr) ₂ O ₃ layer of the comparative coated tools 1 to 13, the respective surfaces are first polished. In the state of the surface, set in a lens barrel of a field emission scanning electron microscope, and apply an electron beam with an acceleration voltage of 15 kV to the surface polishing surface at an incident angle of 70 degrees with an irradiation current of 1 nA. The crystal grains having a hexagonal crystal lattice existing within the measurement range of the surface are irradiated with an electron beam, and an electron backscatter diffraction image apparatus is used to divide the 30 × 50 μm region at an interval of 0.1 μm / step. The angle at which each normal line of each crystal grain intersects the normal line of the surface-polished surface is measured, and from this measurement result, the (0001) plane and {10-10} plane which are the constituent crystal planes of the crystal grain Select and then select In the (0001) plane and {10-10} plane, the angles at which the normal lines of the (0001) plane and the normal lines of the {10-10} plane intersect each other at the interface (grain interface unit) between adjacent crystal grains. The ratio of the crystal grain interface units of 15 degrees or less to the total crystal grain interface units (referred to as the small angle grain interface ratio) was calculated and shown in Tables 5 and 6, respectively.
In addition, the modified (Al, Zr) ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present coated tool 1 to 13 and the conventional (Al) constituting the upper layer of the hard coating layer of the comparative coated tool 1 to 13 , Zr) ₂ O ₃ layer was examined with a transmission electron microscope, and it was confirmed that Zr was segregated at the grain boundaries.

As shown in Tables 5 and 6, respectively, the small-angle grain interface ratio of the modified (Al, Zr) ₂ O ₃ layer of the present invention coated tool is 35% or more, whereas in the comparative coated tool, The small-angle grain interface ratio was less than 35%.

  Further, when the thicknesses of the constituent layers of the hard coating layers of the present coated tools 1 to 13 and the comparative coated tools 1 to 13 were measured using a scanning electron microscope (longitudinal cross section measurement), both of them were the target layer thickness. The substantially same average layer thickness (average value of 5-point measurement) was shown.

Next, for the various coated tools of the present invention coated tools 1-13 and comparative coated tools 1-13, all are screwed to the tip of the tool steel tool with a fixing jig,
[Cutting conditions A]
Work material: JIS / S20C round bar,
Cutting speed: 450 m / min,
Cutting depth: 2.8 mm,
Feed: 0.9 mm / rev,
Cutting time: 5 minutes,
Dry high-speed high-feed cutting test of carbon steel under the conditions (normal cutting speed and feed are 250 m / min, 0.3 mm / rev),
[Cutting conditions B]
Work material: JIS / SCM420 round bar,
Cutting speed: 380 m / min,
Cutting depth: 4.8 mm,
Feed: 0.4 mm / rev,
Cutting time: 5 minutes,
Dry high-speed high-cut cutting test of chrome molybdenum steel under the conditions of (normal cutting speed and cutting is 250 m / min, 2 mm),
[Cutting conditions C]
Work material: JIS / FC300 lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 550 m / min,
Cutting depth: 5.5 mm,
Feed: 0.5 mm / rev,
Cutting time: 5 minutes,
Wet high-speed high-cut cutting test of cast iron under normal conditions (normal cutting speed and cutting is 250 m / min, 2.5 mm)
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 7.

From the results shown in Tables 5 to 7, according to the present invention coated tools 1 to 13, the upper layer of the hard coating layer is formed by vapor deposition as a modified (Al, Zr) ₂ O ₃ layer composed of a composite oxide of Al and Zr. In addition, the modified (Al, Zr) ₂ O ₃ layer has a crystal grain interface arrangement of crystal grains composed of hexagonal crystal lattices with a small-angle grain interface ratio of 35% or more. The high temperature of the Ti compound layer that forms the lower layer of the hard coating layer even in high-speed heavy cutting of steel or cast iron with high-temperature hardness and grain boundary strength, high heat generation, and high load on the cutting edge In addition to strength and high bonding strength, the excellent high temperature hardness and high temperature strength of the modified (Al, Zr) ₂ O ₃ layer significantly improve the chipping resistance of the hard coating layer and provide excellent tool properties over a long period of time. In contrast to the upper layer of the hard coating layer and Te in the conventional (Al, Zr) Comparative ₂ O ₃ layer is deposited formed coated tools 1 to 13, in severe cutting conditions of high speed heavy cutting, particularly the grain boundary strength and high temperature strength of the hard coating layer is insufficient Therefore, it is clear that chipping occurs in the hard coating layer, and the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention has an excellent hard coating layer not only for cutting under normal conditions such as various types of steel and cast iron, but also for high-speed heavy cutting with high heat generation and high load. It exhibits excellent chipping resistance and exhibits excellent cutting performance over a long period of time, so that it can sufficiently satisfy cutting equipment performance, labor saving and energy saving, and cost reduction. It is.

The relationship between the normal of the surface polished surface, the normal of the (0001) plane of the crystal grains composed of hexagonal crystal lattices in the modified (Al, Zr) ₂ O ₃ layer, and the normal of the {10-10} plane is shown. It is a schematic explanatory drawing. It indicates that the angle between the normal lines C and C ′ of the (0001) plane and the normal lines a and a ′ of the {10-10} plane is 15 degrees or less at the interface between adjacent crystal grains. It is a schematic explanatory drawing.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) The lower layer is one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer having an overall average layer thickness of 3 to 20 μm. A Ti compound layer comprising:
(B) The upper layer has an average layer thickness of 2 to 15 μm, is composed of a chemical vapor deposited Al and Zr composite oxide layer, and uses a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. The angle at which each normal of the constituent crystal planes of the crystal grains composed of hexagonal crystal lattices intersects the normal of the polished surface is irradiated with an electron beam to each crystal grain existing within the measurement range of the polished surface. From this measurement result, the (0001) plane and the {10-10} plane which are the constituent crystal planes of the crystal grains are selected, and the selected (0001) plane and {10-10} plane are adjacent to each other. When the angles at which the normals of the (0001) planes and the normals of the {10-10} planes intersect each other at the interface between crystal grains (grain interface unit) are calculated, And the {10-10} plane The crystal grain interface unit in which the crystal grain interface unit whose line crossing angle is 15 degrees or less accounts for 35% or more of the total crystal grain interface unit is shown, and the inclusion of the Zr component in the composite oxide layer of Al and Zr A composite oxide layer of Al and Zr having an atomic ratio (Zr / (Al + Zr)) in a total amount of the Al component and 0.0001 to 0.002.
A surface-coated cutting tool that exhibits excellent chipping resistance with a hard coating layer formed by vapor-depositing the hard coating layer constituted by (a) and (b).

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