JP2008000882A - Surface coated cermet cutting tool having hard coating layer exhibiting excellent chipping resistance and abrasion resistance in high-speed cutting of material hard to cut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated cermet tool having a hard coating layer exhibiting excellent chipping resistance and abrasion resistance in high-speed cutting of a material hard to cut. <P>SOLUTION: In the coated cermet tool comprising the hard coating layer consisting of a lower layer of a Ti compound layer and an upper layer of an αtype Al<SB>2</SB>O<SB>3</SB>layer, a reformed WC layer is intervened between a tool base and the lower layer. A field emission type scanning electron microscope and an electron back-scattered diffraction image device are used to radiate an electronic beam to each crystal grain having a hexagonal crystal grid existing in a measurement range of a surface polished face, so that the angle of the normal line of each crystal face of the crystal grain to the normal line of the surface-polished face where they cross each other is measured. Based on the result of such a measurement, faces (0001) and ä10-10} are selected. Furthermore, in the selected faces (0001) and ä10-10}, a reformed αtype Al<SB>2</SB>O<SB>3</SB>layer showing a crystal grain interface array where a crystal grain interface unit in which the angle of the normal lines of the faces (0001) in the interface (crystal grain interface unit) between respective adjacent crystal grains and the normal lines of the faces ä10-10} where they cross each other is 15° or less occupies 45% or more of the total is obtained to compose the upper layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

In the present invention, an aluminum oxide layer (hereinafter referred to as Al ₂ O ₃ ) layer constituting the upper layer of the hard coating layer has excellent high temperature strength (crystal grain interface strength), and also constitutes a hard coating layer. Since the tungsten carbide (hereinafter referred to as WC) layer suppresses the high temperature hardness reduction of the hard coating layer, the tungsten carbide layer has a particularly high viscosity and also has an adhesiveness to the hard coating layer on the cutting tool surface during cutting. As a result, the cutting resistance is extremely high, and this tendency becomes even more pronounced in high-speed cutting with high heat generation, which is harder in high-speed cutting of difficult-to-cut materials such as mild steel, stainless steel, and high-manganese steel. The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance and wear resistance over a long period of time.

Conventionally, in general, on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a WC-based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet,
(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). A Ti compound layer having a total average layer thickness of 3 to 20 μm, including one or two or more of a layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) Al ₂ O ₃ layer (hereinafter, referred to as α-type Al ₂ O ₃ layer) having an α-type crystal structure in the state of chemical vapor deposition and an average layer thickness of 2 to 20 μm. ,
A coated cermet tool formed by chemical vapor deposition of the hard coating layer composed of (a) and (b) above is known, and this coated cermet tool can be used for cutting various general steels and ordinary cast irons, for example. It is well known that it is used.

Further, in the above-described coated cermet tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and further, the TiCN layer constituting the Ti compound layer as the lower layer is intended to improve the strength of the layer itself. In a normal chemical vapor deposition apparatus, a gas mixture containing organic carbonitrides is used as a reaction gas, and it is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. so that it has a vertically grown crystal structure. It is also known to do.
Japanese Unexamined Patent Publication No. 6-31503 Japanese Patent Laid-Open No. 6-8010

In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. In coated cermet tools, there is no problem when used for high-speed cutting of general steel such as low alloy steel and carbon steel, and ordinary cast iron such as gray cast iron. When used for high-speed cutting of difficult-to-cut materials such as high-manganese steel, the difficult-to-cut material itself has a high viscosity and has high adhesion to the hard coating layer on the surface of the cutting tool during cutting. The trend, combined with a further increase due to the high heat generated during high-speed cutting, has extremely high cutting resistance, while the high-temperature strength of the α-type Al ₂ O ₃ layer that constitutes the hard coating layer can withstand this. As a result, chipping (slight chipping) is likely to occur in the hard coating layer, and at the same time, a significant temperature rise of the hard coating layer due to high heat generation is unavoidable. At present, the service life is reached.

The present inventors have, from the viewpoint as described above, focusing on the conventional coated cermet tool α type the Al ₂ O ₃ layer described above constituting the upper layer of the hard coating layer, in particular α-type the Al ₂ O ₃ layer As a result of research to improve chipping resistance of
(A) The α-type Al ₂ O ₃ layer (hereinafter referred to as a conventional α-type Al ₂ O ₃ layer) as a hard coating layer of the above-described conventional coated cermet tool is generally obtained by using a normal chemical vapor deposition apparatus.
Reaction gas composition: volume%, AlCl ₃ : 2 to 4%, CO ₂ : 4 to 8%, HCl: 1 to 3%, H ₂ S: 0.05 to 0.2%, H ₂ : remaining,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
The α-type Al ₂ O ₃ layer is formed by the same ordinary chemical vapor deposition apparatus, for example,
Reaction gas composition:% by volume, AlCl ₃ : 6 to 10%, CO ₂ : 4 to 8%, HCl: 3 to 5%, H ₂ S: 0.25 to 0.6%, H ₂ : remaining,
Reaction atmosphere temperature: 920 to 1000 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
When the α-type Al ₂ O ₃ layer (hereinafter referred to as a modified α-type Al ₂ O ₃ layer) formed as a result of vapor deposition under the following conditions, the α-type Al ₂ O ₃ layer itself has excellent high-temperature hardness. In addition to heat resistance, it should have a higher temperature strength than the conventional α-type Al ₂ O ₃ layer.

(B) Regarding the conventional α-type Al ₂ O ₃ layer and the modified α-type Al ₂ O ₃ layer, FIG. 1 shows a hexagonal crystal lattice of crystal grains constituting the α-type Al ₂ O ₃ layer, As shown schematically in schematic perspective view of the relationship of the surface polished surface of the α-type Al ₂ O ₃ layer, it exists within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Each crystal grain having a hexagonal crystal lattice is irradiated with an electron beam, and the angle at which each normal line of each crystal plane of the crystal grain intersects the normal line of the surface polished surface is measured. The (0001) plane and the {10-10} plane, which are the constituent crystal planes of the grains, are selected, and, in the selected (0001) plane and {10-10} plane, the interfaces between adjacent grains (crystal grain interfaces) Normals of (0001) planes in units) and {10 If determined angle of intersection of the normal line among the 10} plane, the reforming α type the Al ₂ O ₃ layer is the angle of intersection of the normal line between the normal to each other and {10-10} plane of the (0001) plane 15 In contrast, the conventional α-type Al ₂ O ₃ layer has a method of (0001) plane, whereas a crystal grain interface unit having a degree less than or equal to the degree shows a crystal grain interface arrangement that accounts for 45% or more of the total crystal grain interface unit. The crystal grain interface unit whose angle between the lines and the normal of the {10-10} planes is 15 degrees or less indicates 25% or less of the total crystal grain interface unit, and this result shows that the conventional α-type Al ₂ O ₃ layer The modified α-type Al ₂ O ₃ layer has a crystal grain interface strength superior to that of the modified α-type Al ₂ O ₃ layer. The high temperature strength of the material should be significantly improved.

(C) Generally, the WC layer as a constituent layer of the hard coating layer of the coated cermet tool is a normal chemical vapor deposition apparatus.
Reaction gas composition: volume%, WF ₆ : 0.5 to 5%, C ₆ H ₆ : 0.5 to 10%, H ₂ : 10 to 35%, Ar: remaining,
Reaction atmosphere temperature: 500 to 900 ° C.
Reaction atmosphere pressure: 5 to 15 kPa,
The WC layer is formed by the same chemical vapor deposition apparatus, for example,
Reaction gas composition:% by volume, WF ₆ : 0.04 to 0.4%, CH ₃ CN: 0.06 to 0.6%, NH ₃ : 0.1 to 1%, H ₂ : 40 to 80% , Ar: rest,
Reaction atmosphere temperature: 980-1100 ° C.,
Reaction atmosphere pressure: 5 to 30 kPa,
As a result, the formed WC layer (hereinafter referred to as a modified WC layer) has excellent adhesion, and even in a high temperature environment when the hard coating layer is formed, There is a property that the constituent components cannot diffuse and penetrate. Therefore, when this component is present as a base intervening layer between the tool base and the lower layer of the hard coating layer, both the tool base and the lower layer are firmly adhered to each other. In addition, a component that exhibits extremely high activity in a high-temperature environment at the time of forming a hard coating layer, that is, a component such as Co or Ni that is a binder phase forming component of the tool base, and further a component such as Cr and V into the hard coating layer. Diffusion penetration is prevented, and the hard coating layer retains its inherent characteristics, that is, excellent high-temperature hardness, and as a result, has excellent wear resistance during cutting. That would like to demonstrate to the foot.

(D) Therefore, the modified WC layer is provided as a base intervening layer between the tool base and the lower layer of the hard coating layer, and in addition to excellent high temperature hardness and heat resistance, further improved high temperature strength is achieved. The coated cermet tool formed by depositing the modified α-type Al ₂ O ₃ layer having the upper layer of the hard coating layer on the surface of the tool base together with the lower Ti compound layer is the modified WC layer. In addition to further strengthening the adhesion between the tool base and the hard coating layer, and in combination with preventing diffusion and penetration of the constituent components of the tool base into the hard coating layer, in particular, the cutting resistance is reduced. Even in the high-speed cutting of the above-mentioned difficult-to-cut material, the hard coating layer does not generate chipping and exhibits excellent wear resistance over a long period of time.
The research results (a) to (d) have been obtained.

This invention was made based on the above research results, and on the surface of the tool base,
(A) a Ti compound layer in which the lower layer is composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, and has a total average layer thickness of 3 to 20 μm,
(B) an α-type Al ₂ O ₃ layer whose upper layer has an average layer thickness of 2 to 20 μm;
In the coated cermet tool formed by chemical vapor deposition of the hard coating layer constituted by (a) and (b) above,
(1) A modified WC layer having an average layer thickness of 0.1 to 2 μm as a base intervening layer between the tool base and the lower layer;
With chemical vapor deposition,
(2) The α-type Al ₂ O ₃ layer as the upper layer has an α-type crystal structure in the same chemical vapor deposited state, and is surface polished using a field emission scanning electron microscope and an electron backscatter diffraction image device. Irradiate each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface with an electron beam, and measure the angle at which each normal line of each crystal plane of the crystal grain intersects the normal line 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 between the normals of the (0001) planes and the normals of the {10-10} planes at the interface (grain interface unit) between grains is determined, the normals of the (0001) planes and { Normals of 10-10} planes A modified α-type Al ₂ O ₃ layer showing a crystal grain interface arrangement in which the crystal grain interface units having an angle of 15 degrees or less occupy a ratio of 45% or more of the total crystal grain interface units;
It is characterized by a coated cermet tool that exhibits excellent chipping resistance and wear resistance with a hard coating layer particularly in high-speed cutting of difficult-to-cut materials.

The reason why the numerical values of the constituent layers of the hard coating layer of the coated cermet tool of the present invention are limited as described above will be described below.
(A) Modified WC layer (underlying intervening layer)
As described above, the modified WC layer is tightly bonded to the tool base and the lower Ti compound layer to contribute to improving the adhesion of the hard coating layer to the tool base. It has the effect of preventing the diffusion and penetration of a high binder phase component into the hard coating layer so that the high temperature hardness inherent in the hard coating layer is not impaired, but the average layer thickness is 0 When the thickness is less than 1 μm, the above-mentioned effect cannot be exhibited sufficiently, while an average layer thickness up to 2 μm is sufficient for the above-mentioned action, so the average layer thickness is set to 0.1 to 2 μm.

(B) Ti compound layer (lower layer)
The Ti compound layer basically exists as a lower layer of the modified α-type Al ₂ O ₃ layer, which is the upper layer, and contributes to improving the high temperature strength of the hard coating layer by its excellent high temperature strength. It adheres firmly to both the modified WC layer and the modified α-type Al ₂ O ₃ layer, thus contributing to improving the adhesion of the hard coating layer to the tool substrate, but the total average layer thickness is 3 μm. If the total thickness is less than 20 μm, thermoplastic deformation is likely to occur particularly in high-speed cutting of difficult-to-cut materials with high heat generation. Since it causes uneven wear, the total average layer thickness was determined to be 3 to 20 μm.

(C) Modified α-type Al ₂ O ₃ layer (upper layer)
As described above, in the crystal grain interface arrangement, the angle between the normal lines of the (0001) planes and the normal lines of the {10-10} planes at the interface between adjacent crystal grains (crystal grain interface unit) is 15 degrees. It has been clarified based on many test results that when the following crystal grain interface units occupy a ratio of 45% or more of the total crystal grain interface units, the crystal grain interface strength is further improved. Therefore, when the upper limit of the angle at which each normal intersects is, for example, 16 degrees, or when the proportion of the crystal grain interface unit where the angle between each normal intersects is 15 degrees or less is less than 45% The desired excellent grain interface strength cannot be ensured, and when the above conditions are satisfied, the modified α-type Al ₂ O ₃ layer has the excellent high-temperature hardness of the α-type Al ₂ O ₃ itself and In addition to heat resistance, It comes to have a high temperature strength.
Also, if the average layer thickness is less than 2 μm, the above properties cannot be sufficiently provided in the hard coating layer. On the other hand, if the average layer thickness exceeds 20 μm, chipping particularly in high-speed cutting of difficult-to-cut materials. Therefore, the average layer thickness was determined to be 2 to 20 μm.

  In addition, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone may be vapor-deposited as the outermost surface layer of the hard coating layer as necessary, but the average layer thickness in this case is It may be 0.1 to 1 μm, and if the thickness is less than 0.1 μm, a sufficient discrimination effect cannot be obtained, while the discrimination effect by the TiN layer is sufficient for an average layer thickness of up to 1 μm.

In the coated cermet tool of the present invention, the modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is excellent in addition to the excellent high-temperature hardness and heat resistance of the α-type Al ₂ O ₃ itself. The high-temperature strength and the modified WC layer as the underlying intervening layer contributes to improving the adhesion between the tool substrate and the lower layer of the hard coating layer, and the components of the tool substrate, particularly the bonding, when forming the hard coating layer It prevents the diffusion and penetration of the phase-forming component into the hard coating layer, and thus exhibits the function of maintaining the inherent properties of the hard coating layer itself. Combined with this, even in high-speed cutting of difficult-to-cut materials with particularly high cutting resistance, the hard coating layer has excellent chipping resistance and excellent wear resistance, enabling further extension of the service life. is there.

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

As raw material powders, WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, and Co powder each having an average particle diameter of 1 to 3 μm are prepared. The raw material powder is blended in the blending composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge is subjected to a honing process of R: 0.07 mm. Thus, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were manufactured.

Further, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, blend these raw material powders into the composition shown in Table 2, wet mix with a ball mill for 24 hours, dry, and press-mold into a green compact at 98 MPa pressure The green compact is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.07 mm. Tool bases a to f made of TiCN-based cermet having a chip shape conforming to ISO standards / CNMG 120212 were formed.

Then, each of these tool bases A to F and tool bases a to f is charged into a normal chemical vapor deposition apparatus,
(A) First, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in JP-A-6-8010, and the other conditions are ordinary granularity. The modified WC layer and the Ti compound layer having the target layer thicknesses shown in Table 4 are vapor-deposited as the base intervening layer and the lower layer of the hard coating layer under the conditions shown in Table 4). ,
(B) Next, the reaction gas composition: volume%, AlCl ₃ : a predetermined amount within the range of 6 to 10%, CO ₂ : 6%, HCl: 4%, H ₂ S: 0.25 to 0.6 Predetermined amount% within range, H ₂ : remaining,
Reaction atmosphere temperature: 960 ° C.
Reaction atmosphere pressure: 8 kPa,
The coated cermet tools 1 to 13 of the present invention were manufactured by vapor-depositing a modified α-type Al ₂ O ₃ layer as the upper layer, with the target layer thickness shown in Table 4 under the same conditions.

For comparison purposes, the conventional α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer,
Reaction gas composition: volume%, AlCl ₃ : predetermined amount in the range of 2-4%, CO ₂ : 6%, HCl: 2%, H ₂ S: in the range of 0.05-0.2% Quantitative, H ₂ : remaining,
Reaction atmosphere temperature: 1030 ° C.
Reaction atmosphere pressure: 8 kPa,
The conventional coated cermet tools 1 to 13 are formed under the same conditions except that the target layer thickness as shown in Table 5 is formed and the modified WC layer that is the base intervening layer is not formed. Manufactured.

Subsequently, the modified α-type Al ₂ O ₃ layer and the conventional α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the above-described coated cermet tool 1-13 of the present invention and the conventional coated cermet tool 1-13, Using a field emission scanning electron microscope, the grain boundary arrangement was investigated.
State, that is, the conventional α-type the Al ₂ O ₃ layer of the modified α type the Al ₂ O ₃ layer and the conventional coated cermet tools 1-13 of the invention as described above coated cermet tools 1 to 13, in which the respective surface and the polishing surface The measurement range of each surface polished surface 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 surface polished surface with an irradiation current of 1 nA. Each crystal grain having a hexagonal crystal lattice existing therein is irradiated, and using an electron backscatter diffraction image apparatus, a region of 30 × 50 μm is formed at an interval of 0.1 μm / step on each crystal plane of the crystal grain. The angle at which each normal intersects the normal of the surface-polished surface was measured. From this measurement result, the (0001) plane and the {10-10} plane, which are the constituent crystal planes of the crystal grains, were selected and further selected. (0001 In the plane and the {10-10} plane, the angles at which the normal lines of the (0001) plane and the normal lines of the {10-10} plane intersect each other at the interface between adjacent crystal grains (grain interface unit) are obtained, The ratio of the crystal grain interface units having an angle between the normals of the (0001) planes and the normal lines of the {10-10} planes of 15 degrees or less to the total grain interface units (hereinafter referred to as an intersection angle of 15 degrees or less) (Referred to as the ratio of crystal grain interface units) and are shown in Tables 4 and 5, respectively.

As shown in Tables 4 and 5, each of the modified α-type Al ₂ O ₃ layers of the coated cermet tools 1 to 13 of the present invention is a crystal having a crystal grain interface unit ratio of 45% or more with an intersection angle of 15 degrees or less. Whereas the conventional α-type Al ₂ O ₃ layer of the conventional coated cermet tools 1 to 13 shows a grain interface arrangement, the ratio of the crystal grain interface units with a crossing angle of 15 degrees or less is 25% or less. The sequence was shown.

  Moreover, when the thickness of the constituent layer of the hard coating layer of the present coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13 obtained as a result was measured using a scanning electron microscope (longitudinal section measurement). , Each showed an average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness.

Next, for the various coated cermet tools of the present invention coated cermet tool 1-13 and the conventional coated cermet tool 1-13, all of them are screwed with a fixing jig to the tip of the tool steel tool,
Work material: JIS / SUS430 round bar,
Cutting speed: 275 m / min. ,
Incision: 2.5mm,
Feed: 0.1 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous high-speed cutting test (normal cutting speed 150 m / min.) Of stainless steel under the following conditions (referred to as cutting conditions A),
Work material: JIS / S15C lengthwise equal length 4 vertical grooved round bars,
Cutting speed: 310 m / min. ,
Cutting depth: 2mm,
Feed: 0.2 mm / rev. ,
Cutting time: 10 minutes,
Dry interrupted high-speed cutting test (normal cutting speed is 200 m / min.) Of mild steel under the following conditions (referred to as cutting conditions B),
Work material: JIS / SMn443 round bar,
Cutting speed: 300 m / min. ,
Cutting depth: 2mm,
Feed: 0.1 mm / rev. ,
Cutting time: 10 minutes,
A dry continuous high-speed cutting test (normal cutting speed is 180 m / min.) Of high manganese steel under the above conditions (referred to as cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 6.

From the results shown in Tables 4 to 6, the coated cermet tools 1 to 13 of the present invention all have crystal grain interface units in which the modified α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer, has an intersection angle of 15 degrees or less. As a result, the modified α-type Al ₂ O ₃ layer has not only excellent high-temperature hardness and heat resistance, but also excellent crystal grain interface strength, that is, excellent high-temperature. Further, the modified WC layer provided as a base intervening layer contributes to improving the adhesion between the tool substrate and the lower layer of the hard coating layer, and is a component of the tool substrate, particularly a binder phase forming component. In combination with the excellent high-temperature strength of the lower Ti compound layer, it prevents diffusion and penetration into the hard coating layer and thus maintains the excellent high-temperature hardness of the hard coating layer itself. , Especially for difficult-to-cut materials with extremely high cutting resistance Speed without occurrence of chipping at the cutting, good against indicate wear resistance, the conventional α-type which is the upper layer of the hard layer the Al ₂ O ₃ layer of grain interface array crossing angle of 15 degrees or less of the crystal grains in The ratio of the interface unit is 25% or less. As a result, the conventional α-type Al ₂ O ₃ layer does not have a sufficiently satisfying high-temperature strength, and the binder phase forming component in the tool base diffuses into the hard coating layer. In the conventional coated cermet tools 1 to 13 that cannot be satisfactorily prevented, it is clear that chipping occurs in the hard coating layer by high-speed cutting of difficult-to-cut materials, and the service life is reached in a relatively short time. is there.

  As described above, the coated cermet tool of the present invention has a high viscosity in addition to high-speed cutting such as various steels and cast irons, and has a high viscosity with respect to the hard coating layer on the surface of the cutting tool at the time of cutting. Even with high-speed cutting of difficult-to-cut materials such as mild steel, stainless steel, and high-manganese steel, which have high adhesiveness, resulting in extremely high cutting resistance, it shows excellent wear resistance without chipping. Since it exhibits excellent cutting performance, 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.

a hexagonal crystal lattice with crystal grains constituting the α-type the Al ₂ O ₃ layer, the surface polishing plane relationship of the α-type Al ₂ O ₃ layer which is the schematic perspective view schematically showing.

Claims (1)

On the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) The lower layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer, and a total average of 3 to 20 μm A Ti compound layer having a layer thickness,
(B) an aluminum oxide layer in which the upper layer has an α-type crystal structure in the state of chemical vapor deposition and has an average layer thickness of 2 to 20 μm;
In the surface-coated cermet cutting tool formed by chemical vapor deposition of the hard coating layer composed of (a) and (b) above,
(1) A modified tungsten carbide layer having an average layer thickness of 0.1 to 2 μm as a base intervening layer between the tool base and the lower layer,
With chemical vapor deposition,
(2) The aluminum oxide layer as the upper layer has an α-type crystal structure in the same chemical vapor deposition state, and a surface polished surface measurement range using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. The crystal grains having a hexagonal crystal lattice existing therein are irradiated with an electron beam, and the angle at which each normal line of each crystal plane of the crystal grains intersects the normal line of the surface polished surface is measured. From the results, the (0001) plane and the {10-10} plane, which are the constituent crystal planes of the crystal grains, are selected, and in the selected (0001) plane and {10-10} plane, the interfaces between adjacent crystal grains are respectively selected. When the angle between the normals of the (0001) planes and the normals of the {10-10} planes in (crystal grain interface unit) is determined, the normals of the (0001) planes and {10-10} Surface normal Reforming the aluminum oxide layer angle indicating the crystal grain interface array which occupies 15 degrees or less grain boundaries units the percentage of 45% or more of the total grain surface unit of intersection of Judges,
A surface-coated cermet cutting tool whose hard coating layer exhibits excellent chipping resistance and wear resistance in high-speed cutting of difficult-to-cut materials.

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