JP2007167987A - Surface coated cermet-made cutting tool having hard coating layer exhibiting excellent chipping resistance in high-speed cutting material hard to cut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cermet-made cutting tool having a hard coating layer exhibiting excellent chipping resistance in high-speed cutting material hard to cut. <P>SOLUTION: In this surface coated cermet-made cutting tool, on the surface of a tool base, a hard coating layer is formed by vapor deposition. The hard coating layer includes: a lower layer, which is a Ti compound layer having an average layer thickness ranging from 3 to 20 μm; and an upper layer, which is a modified α type Al<SB>2</SB>O<SB>3</SB>layer having an average layer thickness ranging from 1.5 to 5.9 μm. The following α type Al<SB>2</SB>O<SB>3</SB>layer is interposed as a reinforcement layer between the lower layer and the upper layer. An inclination angle frequency distribution graph is created by measuring an angle of inclination made by a normal of (0001) face, which is a crystalline plane of a crystal grain using a field emission scanning electron microscope. The α type Al<SB>2</SB>O<SB>3</SB>layer has the highest peak in a section of inclination angle ranging from 75 to 90 degrees and shows an inclination angle frequency distribution graph in which the total frequency present in the range from 75 to 90 degrees occupies the ratio of 50% or more of the entire frequency. The layer also has an average layer thickness ranging from 0.1 to 1.9 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  This invention has a high viscosity, and has a high adhesion to the hard coating layer on the surface of the cutting tool during cutting. As a result, mild steel, stainless steel, and high manganese steel that have extremely high cutting resistance. This is a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance with a hard coating layer in high-speed cutting of difficult-to-cut materials, and exhibits excellent wear resistance over a long period of time. It is.

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) 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) The upper layer has an α-type crystal structure in the state of chemical vapor deposition, and using a field emission scanning electron microscope, as shown schematically in FIG. 2, is a polished surface parallel to the tool base surface. Each of the crystal grains having a hexagonal crystal lattice existing within the measurement range is irradiated with an electron beam, and the normal line of the (0001) plane that is the crystal plane of the crystal grain is relative to the normal line of the polished surface. Measure the inclination angle to be made, divide the measurement inclination angle within the range of 0-45 degrees out of the measurement inclination angle for each pitch of 0.25 degree, and totalize the frequency existing in each division In the inclination angle number distribution graph, as shown in FIG. 4, the highest peak exists in the inclination angle section in the range of 0 to 15 degrees, and the sum of the frequencies existing in the range of 0 to 15 degrees is as follows. , Accounting for 50% or more of the total frequency in the slope angle distribution graph It shows an inclination angle frequency distribution graph, and an aluminum oxide layer having an average layer thickness of 1.5～6Myuemu (hereinafter, referred to as modified α type the Al ₂ O ₃ layer),
A coated cermet tool formed by vapor-depositing a hard coating layer composed of the above (a) and (b) is known, and this coated cermet tool has the modified α-type Al ₂ O ₃ layer formed of α-type Al. ₂ O ₃ itself has excellent high-temperature hardness and heat resistance, as well as excellent high-temperature strength, so it is excellent even when used for high-speed cutting such as various general steels and ordinary cast iron. It is also known to exhibit excellent chipping resistance and excellent cutting performance over a long period of time.

In general, the modified α-type Al ₂ O ₃ layer constituting the hard coating layer of the above coated cermet tool uses a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 1~5%,} CO 2: 0.1~2%, HCl: 0.3~3%, H 2 S: 0.5~1%, Ar: 20~ 35%, H ₂ : remaining,
Reaction atmosphere temperature: 1050 to 1100 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
It is also known that vapor deposition is performed under the following conditions.
Furthermore, the Ti compound layer and the modified α-type Al ₂ O ₃ layer that also constitute the hard coating layer have a granular crystal structure, and the TiCN layer that constitutes the Ti compound layer is intended to improve the strength of the layer itself. In a normal chemical vapor deposition apparatus, a mixed gas containing organic carbonitride is used as a reaction gas, and it is formed by chemical vapor deposition at a medium temperature range of 700 to 950 ° C. so that it has a vertically grown crystal structure. It is also known to do.
JP-A-2005-205586 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, and along with this, cutting has been on the trend of higher speed. For 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 manganese steel, the difficult-to-cut material itself has a high viscosity, and the adhesiveness to the hard coating layer on the surface of the cutting tool during cutting is also high. Combined with a further increase due to high heat generated during high-speed cutting, the cutting resistance becomes extremely high, while the high-temperature strength of the modified α-type Al ₂ O ₃ layer constituting the hard coating layer can withstand this. This is not sufficient, and as a result, chipping (slight chipping) is likely to occur at the cutting edge, and this causes the service life to be reached in a relatively short time.

In view of the above, the present inventors focused on the coated cermet tool in which the modified α-type Al ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and in particular, the modified α-type Al As a result of research to improve chipping resistance of ₂ O ₃ layer,
Between the Ti compound layer (lower layer) and the modified α-type Al ₂ O ₃ layer (upper layer) constituting the hard coating layer of the above conventional coated cermet tool, using a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 1~5%,} CO 2: 3~7%, HCl: 0.3~3%, H 2 S: 0.02~0.4%, H 2: remainder ,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 20-30 kPa,
When an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer is formed with an average layer thickness of 0.1 to 1.9 μm under the conditions of the above, the resulting Al ₂ O ₃ layer has the same α-type crystal structure. Using a field emission scanning electron microscope, as shown in FIGS. 1 (a) and 1 (b), it has a hexagonal crystal lattice that is also present in the measurement range of the polished surface parallel to the tool substrate surface. Each crystal grain is irradiated with an electron beam, an inclination angle formed by a normal line of the (0001) plane that is a crystal plane of the crystal grain is measured with respect to the normal line of the polished surface, When the measured inclination angle in the range of 45 to 90 degrees is divided into pitches of 0.25 degrees and the frequency existing in each of the divisions is represented by an inclination angle number distribution graph, FIG. As shown in Fig. 4, a sharp peak appears at a specific position in the tilt angle section, and According to the results, when the reaction atmosphere pressure in the chemical vapor deposition apparatus is changed within the range of 20 to 30 kPa as described above, the position where the sharpest peak appears changes within the range of 75 to 90 degrees of the inclination angle section. In addition, the sum of the frequencies existing within the range of 75 to 90 degrees occupies a ratio of 50% or more of the entire frequencies in the inclination angle distribution graph, and 75 to 75 in the inclination angle distribution graph as a result. An Al ₂ O ₃ layer (hereinafter referred to as a reinforced α-type Al ₂ O ₃ layer) in which the highest peak of the tilt angle section appears in the range of 90 degrees is referred to as the above-mentioned modified α-type Al ₂ O ₃ layer (upper layer). be between Ti compound layer (lower layer), the modified α type the Al ₂ O ₃ layer were sufficiently reinforced, the reforming α-type Al ₂ O even at high cutting with high cutting resistance above hard-to-cut materials Suppresses chipping in ₃ layers As a result, the coated cermet tool exhibits excellent wear resistance over a long period of time.
The research result was 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) The upper layer is irradiated with an electron beam to each crystal grain having a hexagonal crystal lattice existing in a measurement range of a polished surface parallel to the tool substrate surface using a field emission scanning electron microscope, The inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain is measured with respect to the normal line of the polished surface, and the measurement inclination is in the range of 0 to 45 degrees among the measurement inclination angles. In the inclination angle distribution graph obtained by dividing the angle for each pitch of 0.25 degrees and counting the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 15 degrees. In addition, an inclination angle number distribution graph in which the sum of the frequencies existing in the range of 0 to 15 degrees occupies a ratio of 50% or more of the entire degrees in the inclination angle number distribution graph is shown, and 1.5 to 5.9 μm. A modified α-type Al ₂ O ₃ layer having an average layer thickness of
In the coated cermet tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
Using a field emission scanning electron microscope as a reinforcing layer between the Ti compound layer as the lower layer and the modified α-type Al ₂ O ₃ layer as the upper layer, a polished surface parallel to the tool base surface is used. Each crystal grain having a hexagonal crystal lattice existing in the measurement range is irradiated with an electron beam, and the normal line of the (0001) plane that is the crystal plane of the crystal grain is formed with respect to the normal line of the polished surface. The inclination angle is measured, and among the measurement inclination angles, the measurement inclination angles within a range of 45 to 90 degrees are divided for each pitch of 0.25 degrees, and the frequencies existing in each division are totaled. In the tilt angle distribution graph,
The highest peak exists in the inclination angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees represents a ratio of 50% or more of the entire degrees in the inclination angle frequency distribution graph. Reinforced α-type Al ₂ O ₃ layer showing an inclination angle number distribution graph and having an average layer thickness of 0.1 to 1.9 μm,
It is characterized by a coated cermet tool that exhibits excellent chipping resistance in a high-speed cutting process of difficult-to-cut materials with a hard coating layer.

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) 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, and allows the hard coating layer to have high-temperature strength by its excellent high-temperature strength. And the reinforcing α-type Al ₂ O ₃ layer firmly adhere to each other, and thus have an effect of improving the adhesion of the hard coating layer to the tool substrate. However, when the total average layer thickness is less than 3 μm, On the other hand, if the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation particularly in high-speed cutting with high heat generation, which causes uneven wear. The total average layer thickness was determined to be 3-20 μm.

(B) modified α type the Al ₂ O ₃ layer (upper layer)
The maximum peak position of the measured inclination angle in the inclination angle number distribution graph of the modified α-type Al ₂ O ₃ layer is changed by changing the reaction atmosphere pressure in the chemical vapor deposition apparatus. When the reaction atmosphere pressure is 6 to 10 kpa, the highest peak appears in the inclination angle section in the range of 0 to 15 degrees, and the total of the frequencies existing in the range of 0 to 15 degrees is the inclination angle. An inclination angle number distribution graph occupying a ratio of 50% or more of the entire frequency in the number distribution graph is shown. Therefore, even if the reaction atmosphere pressure is out of the range, it is out of the range. However, the highest peak of the measurement inclination angle does not appear within the range of 0 to 15 degrees, and in such a case, the desired excellent high-temperature strength cannot be provided.
The modified α-type Al ₂ O ₃ layer also has high-temperature strength in addition to the excellent high-temperature hardness and heat resistance of the α-type Al ₂ O ₃ itself, but the average layer thickness is 1 If the thickness is less than 5 μm, the above properties cannot be sufficiently provided in the hard coating layer, and if the average layer thickness exceeds 5.9 μm, chipping is likely to occur in high-speed cutting of difficult-to-cut materials. Therefore, the average layer thickness was determined to be 1.5 to 5.9 μm.

(C) Reinforced α-type Al ₂ O ₃ layer (reinforcing layer)
As described above, the highest peak position of the measured inclination angle in the inclination angle number distribution graph of the reinforced α-type Al ₂ O ₃ layer changes by changing the reaction atmosphere pressure in the chemical vapor deposition apparatus, but according to the test results, When the reaction atmosphere pressure in the above deposition conditions is 20 to 30 kPa, the maximum peak appears in the tilt angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees is The inclination angle number distribution graph occupies a ratio of 50% or more of the entire frequency in the inclination angle number distribution graph. Therefore, even if the reaction atmosphere pressure is out of the range, it is high. Even if it deviates, the maximum peak of the measured inclination angle does not appear within the range of 75 to 90 degrees, and in this case, the desired excellent reinforcing action cannot be exhibited. It is a thing.
Further, if the average layer thickness is less than 0.1 μm, the reinforcing action on the modified α-type Al ₂ O ₃ layer is insufficient, while if the average layer thickness exceeds 1.9 μm, the difficult-to-cut material Since high-speed cutting tends to cause chipping, the average layer thickness is set to 0.1 to 1.9 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 interposed between the modified α-type Al ₂ O ₃ layer and the Ti compound layer to reinforce α Since the type Al ₂ O ₃ layer is sufficiently reinforced, the hard coating layer has excellent wear resistance without causing chipping even in high-speed cutting of difficult-to-cut materials with high cutting resistance, further extending the service life Is possible.

  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 was blended in the blending composition shown in Table 1, and then added with wax, mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then 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 the raw material powder, both (in mass ratio, TiC / TiN = 50/50 ) TiCN having an average particle diameter of 0.5~2μm powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC 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. Under the conditions shown in Table 4 and 5), the Ti compound layer having the target layer thickness shown in Tables 4 and 5 is deposited as the lower layer of the hard coating layer.
(B) Next, reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 5%, HCl: 2%, H ₂ S: 0.15%, H ₂ : remaining,
Reaction atmosphere temperature: 850 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 20-30 kPa,
A reinforced α-type Al ₂ O ₃ layer is formed by vapor deposition at the target layer thickness shown in Tables 4 and 5 under the conditions of
(C) Furthermore, the reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 1.5%, HCl: 2%, H ₂ S: 0.75%, Ar: 26.5%, H ₂ : Remaining
Reaction atmosphere temperature: 1070 ° C.
Reaction atmosphere pressure: a predetermined pressure within a range of 6 to 10 kPa,
The coated cermet tools 1 to 13 of the present invention were manufactured by depositing a modified α-type Al ₂ O ₃ layer as an upper layer, with the target layer thicknesses shown in Tables 4 and 5 under the same conditions.

For comparison purposes, as shown in Tables 6 and 7, a reinforced α-type Al ₂ is provided between the modified α-type Al ₂ O ₃ layer that is the upper layer of the hard coating layer and the Ti compound layer that is the lower layer. Conventionally coated cermet tools 1 to 13 were manufactured under the same conditions except that the O ₃ layer was not formed.

Subsequently, the modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present invention coated cermet tool 1-13 and the conventional coated cermet tool 1-13, and the present invention coated cermet tool 1-1 With respect to the 13 reinforced α-type Al ₂ O ₃ layers, inclination angle number distribution graphs were respectively prepared using a field emission scanning electron microscope.
That is, the inclination angle number distribution graph shows the modified α-type Al ₂ O ₃ layer of the present invention coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13 and the reinforcement of the present coated cermet tools 1 to 13. The α-type Al ₂ O ₃ layer is set in a lens barrel of a field emission scanning electron microscope with each surface parallel to the surface of the tool base being a polished surface, and incident on the polished surface at an incident angle of 70 degrees. An electron backscatter diffraction image apparatus is used to irradiate an electron beam having an acceleration voltage of 15 kV with an irradiation current of 1 nA on each crystal grain having a hexagonal crystal lattice existing within the measurement range of each polished surface, The inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line of the polished surface at an interval of 0.1 μm / step in a region of × 50 μm. Based on before Among the measurement inclination angle, the 0-45 degrees for reforming α type the Al ₂ O ₃ layer, the measurement inclination angle is in the range of 45 to 90 degrees for the reinforcement α type the Al ₂ O ₃ layer 0.25 This was created by dividing the pitch for each degree and counting the frequencies existing in each division.

In the gradient angle distribution graphs of the various modified α-type Al ₂ O ₃ layers and reinforced α-type Al ₂ O ₃ layers obtained as a result, as shown in Tables 4 to 7, the coated cermet tools 1 to 1 of the present invention are used. 13 and the modified α-type Al ₂ O ₃ layer of the conventional coated cermet tools 1 to 13, the distribution of the measured inclination angle of the (0001) plane shows the highest peak in the inclination angle section within the range of 0 to 15 degrees, respectively. An inclination angle number distribution graph is shown. On the other hand, in the reinforcing α-type Al ₂ O ₃ layer of the coated cermet tools 1 to 13 of the present invention, an inclination angle number distribution graph in which the highest peak appears in the inclination angle section within the range of 75 to 90 degrees. Was shown.
Tables 4 to 7 show ranges of 0 to 15 degrees and 75 to 90 degrees in the inclination angle number distribution graphs of the various modified α-type Al ₂ O ₃ layers and reinforced α-type Al ₂ O ₃ layers, respectively. The ratio of the total number of tilt angles existing in the tilt angle section to the entire tilt angle distribution graph is shown.
3 is an inclination angle number distribution graph of the reinforced α-type Al ₂ O ₃ layer of the coated cermet tool 4 of the present invention, and FIG. 4 is an inclination angle number distribution graph of the modified α-type Al ₂ O ₃ layer.

  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 / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 350 m / min. ,
Cutting depth: 1mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 minutes
Dry intermittent 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 / SS400 lengthwise equidistant 4 round bars with flutes,
Cutting speed: 400 m / min. ,
Cutting depth: 1mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 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 / SCMnH1 round bar,
Cutting speed: 450 m / min. ,
Incision: 1.5mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes
The dry continuous high-speed cutting test (normal cutting speed is 250 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 8.

From the results shown in Tables 4 to 8, each of the coated cermet tools 1 to 13 of the present invention is between the Ti compound layer that is the lower layer of the hard coating layer and the modified α-type Al ₂ O ₃ layer that is the upper layer. The intervening reinforced α-type Al ₂ O ₃ layer shows the highest peak in the inclination angle section within the range of 75 to 90 degrees in the inclination angle number distribution graph of the (0001) plane, and this action makes the modified α type Since the Al ₂ O ₃ layer is sufficiently reinforced, it exhibits excellent wear resistance without occurrence of chipping even in high-speed cutting of difficult-to-cut materials with extremely high cutting resistance, whereas the reinforcing α In the conventional coated cermet tools 1 to 13 having no interstitial formation of a type Al ₂ O ₃ layer, all of them are hard coated in high-speed cutting of difficult-to-cut materials due to insufficient strength of the modified α-type Al ₂ O ₃ layer. It is clear that chipping occurs in the layer and the service life is reached in a relatively short time. It is how.

  As described above, the coated cermet tool of the present invention has high viscosity in addition to high-speed cutting such as various types of steel and cast iron, and particularly has a high viscosity and adheres to the hard coating layer on the surface of the cutting tool during cutting. Even in high-speed cutting of difficult-to-cut materials such as mild steel, stainless steel, and high manganese steel, which has extremely high cutting resistance, it exhibits 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 cutting, and the cost reduction.

Is a schematic diagram illustrating a measurement range of the inclination angle in the case of measuring the crystal grains (0001) plane in the reinforcement α type the Al ₂ O ₃ layer constituting the hard layer of the present invention coated cermet tool. It is a schematic explanatory drawing which shows the measurement range of the inclination angle in the case of measuring the (0001) plane of the crystal grain in the modified α-type Al ₂ O ₃ layer constituting the hard coating layer. The inclination angle frequency distribution graph showing the tilt angle sections of 45 to 90 degrees to the present invention coated cermet reinforced α type constituting the hard layer of the tool 4 Al ₂ O ₃ layer. The inclination angle frequency distribution graph showing the tilt angle sections of 0 to 45 degrees of the modified α type the Al ₂ O ₃ layer constituting the hard layer of the present invention coated cermet tool 4.

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 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) A hexagonal crystal lattice in which the upper layer has an α-type crystal structure in the state of chemical vapor deposition and exists within a measurement range of a polished surface parallel to the tool substrate surface using a field emission scanning electron microscope And measuring the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, with respect to the normal line of the polished surface. In the inclination angle number distribution graph formed by dividing the measured inclination angles in the range of 0 to 45 degrees for each pitch of 0.25 degrees and totaling the frequencies existing in each section, 0 to 15 An inclination angle in which the highest peak exists in the inclination angle section within the range of degrees, and the total of the frequencies existing within the range of 0 to 15 degrees accounts for 50% or more of the entire degrees in the inclination angle frequency distribution graph A number distribution graph is shown and a 1.5 to 5.9 μm flat A modified α-type aluminum oxide layer having a uniform thickness;
In the surface-coated cermet cutting tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
A field emission scanning electron microscope having an α-type crystal structure in the same chemical vapor deposition state as a reinforcing layer between the Ti compound layer as the lower layer and the modified α-type aluminum oxide layer as the upper layer. And irradiating each crystal grain having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the tool substrate surface with respect to the normal line of the polished surface. The inclination angle formed by the normal line of the (0001) plane which is a crystal plane is measured, and among the measurement inclination angles, the measurement inclination angles within the range of 45 to 90 degrees are divided for each pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by counting the frequencies existing in each section,
The highest peak exists in the inclination angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees represents a ratio of 50% or more of the entire degrees in the inclination angle frequency distribution graph. An α-type aluminum oxide layer showing an inclination angle number distribution graph and having an average layer thickness of 0.1 to 1.9 μm;
A surface-coated cermet cutting tool that exhibits excellent chipping resistance in high-speed cutting of difficult-to-cut materials characterized by the inclusion of

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