JP2005279912A - Surface coated cermet-made cutting tool having hard coating layer exhibiting excellent chipping resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cermet-made cutting tool, the hard coating layer of which exhibits excellent chipping resistance. <P>SOLUTION: A hard coating layer composed of the following (a) and (b) is formed on the surface of a tool base forming a surface coated cermet-made cutting tool. (a) A lower layer is a Ti-compound layer formed of one or two or more layers selected from a TiC layer, a TiN layer, a TiCN layer, a TiCO layer and a TiCNO layer which are all formed by chemical vapor deposition and having the total average layer thickness ranging from 3 to 20 μm, and (b) an upper layer is a thermal transformation α type Al-Zr oxide layer having a κ-type or θ-type crystal structure in the chemical deposition formation state, in which the surface of the Al-base oxide layer satisfying a specified composition formula is subjected to the thermal transformation treatment in the state where a Ti oxide layer is formed with the average layer thickness ranging from 0.05 to 1.5 μm by chemical vapor deposition, thereby transforming the crystal structure of the Al-Zr oxide layer having the κ-type or θ-type crystal structure to the α type crystal structure, and the average layer thickness is 1 to 15 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance with a hard coating layer, particularly in high-speed intermittent cutting of steel or cast iron.

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) As a lower layer, a Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition, Ti compound layer comprising one or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 3 to 20 μm ,
(B) a vapor-deposited α-type aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer having an α-type crystal structure in the state of chemical vapor deposition and having an average layer thickness of 1 to 15 μm as an upper layer;
A coated cermet tool formed by forming a hard coating layer composed of (a) and (b) above is known, and this coated cermet tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is also known that

In general, the Ti compound layer and vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the above coated cermet tool have a granular crystal structure, and the TiCN layer constituting the Ti compound layer is For the purpose of improving its own strength, by performing chemical vapor deposition at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride such as CH ₃ CN as a reaction gas in a normal chemical vapor deposition apparatus. It is also known to form a vertically elongated crystal structure.
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. For coated cermet tools, there is no problem when this is used for continuous cutting and interrupted cutting under normal conditions such as steel and cast iron. The Ti compound layer, which is the lower layer of the hard coating layer, has high-temperature strength and excellent chipping resistance when used for high-speed intermittent cutting that is repeatedly subjected to mechanical thermal shock at a very short pitch. The vapor-deposited α-type Al ₂ O ₃ layer constituting the layer is excellent in high-temperature hardness and heat resistance, but is extremely brittle against mechanical thermal shock. Chipping (small chipping) is likely to occur, and as a result, the service life is reached in a relatively short time.

In view of the above, the present inventors have conducted research to improve the chipping resistance of the vapor-deposited α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the above coated cermet tool. result,
On the surface of the tool base, after forming the Ti compound layer under normal conditions as a lower layer with a normal chemical vapor deposition apparatus, it has a κ-type or θ-type crystal structure under the same normal conditions, and ,
Composition _{formula: (Al 1-X Zr X} ) 2 O 3,
In this case, an Al—Zr oxide [hereinafter referred to as (Al, Zr) ₂ O _3] in which the X value is in an atomic ratio and satisfies 0.003 to 0.05 as measured by an electron beam microanalyzer (EPMA). The layer is formed by vapor deposition,
Then, on the surface of the (Al, Zr) ₂ O ₃ layer, using the same chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, TiCl 4: 0.2~3%,} CO 2: 0.2~10%, Ar: 5~50%, H 2: remainder,
Reaction atmosphere temperature: 900-1020 ° C.
Reaction atmosphere pressure: 7-30 kPa,
Time: 25-100 minutes
In the condition of
Composition formula: TiO _Y ,
The Ti oxide layer measured by an Auger spectroscopic analyzer and satisfying a Y value of 1.2 to 1.9 in terms of atomic ratio to Ti is an average layer thickness of 0.05 to 1.5 μm. Forming,
In this state, heat transformation treatment, preferably pressure: 7-50 kPa in an Ar atmosphere, temperature: 1000-1200 ° C. under conditions of holding for 10 to 120 minutes,
When to transform the (Al, Zr) ₂ O ₃ layer of the κ-type or θ-type crystal structure (Al, Zr) ₂ O ₃ layer of α-type crystal structure, the transformation before (Al, Zr) ₂ O _By the action of the Ti oxide layer formed on the surface of the _three layers, the transformation from the κ-type or θ-type crystal structure to the α-type crystal structure occurs simultaneously on the entire surface, and the progress of the heating transformation is remarkably accelerated. As a result, cracks generated during transformation are in a very fine and uniformly distributed state, and the high temperature of the (Al, Zr) ₂ O ₃ layer itself due to the action of Zr as a constituent component. Since the strength is remarkably improved, the heat-transformed α-type (Al, Zr) ₂ O ₃ layer formed as a result has a uniform structure in which transformation cracks are made fine throughout the layer. Have high strength and are extremely resistant to mechanical thermal shock Becomes solid ones, now includes the excellent chipping resistance, therefore, the upper layer of the hard coating layer the heat transformation α-type (Al, Zr) ₂ O ₃ layer, the lower layer is the Ti compound layer (this The Ti compound layer is not subject to any change in the heat transformation treatment under the above conditions), and the coated cermet tool is particularly suitable for high-speed intermittent cutting with intense mechanical and thermal shock. The transformation α-type (Al, Zr) ₂ O ₃ layer has excellent high-temperature hardness and heat resistance equivalent to those of the α-type Al ₂ O ₃ layer. Since the chipping property is exhibited, the occurrence of chipping in the hard coating layer is remarkably suppressed in combination with the coexistence of the Ti compound layer having excellent high-temperature strength so that excellent wear resistance is exhibited over a long period of time. To become a,

(B) About the above-mentioned conventional vapor deposition α-type Al ₂ O ₃ layer and the above-mentioned heat-transformed α-type (Al, Zr) ₂ O ₃ layer of (a),
Using a field emission scanning electron microscope, as shown in the schematic explanatory diagrams in FIGS. 1A and 1B, an electron beam is individually applied to each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface. Irradiation is performed to measure the inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain with respect to the normal line of the surface-polished surface. When the measured inclination angle within the range is divided for each pitch of 0.25 degrees and the inclination angle number distribution graph is created by summing up the frequencies existing in each division, the conventional vapor deposition α-type Al ₂ As illustrated in FIG. 3, the O ₃ layer exhibits an unbiased inclination angle number distribution graph in the range of the measured inclination angle of the (0001) plane within the range of 0 to 45 degrees, whereas the heating transformation α-type (Al, Zr) ₂ O ₃ layer, as illustrated in FIG. 2, the specific position of the tilt angle segment Sharp highest peak appears, the sharp highest peak, the composition formula of the Ti oxide layer: appearing in the tilt angle sections of the graph the horizontal axis by changing the Y value at the TiO _Y position changes that.

(C) According to the test results, when the Y value in the composition formula: TiO _Y of the Ti oxide layer is 1.2 to 1.9 in terms of the atomic ratio to Ti as described above, the sharpest peak is inclined. Inclination angle number distribution that appears in the range of 0 to 10 degrees of the angular section and the total of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle distribution graph In the resulting slope angle distribution graph, the ratio of the slope angle number in the range of 0 to 10 degrees occupies 45% or more, and the slope angle section is in the range of 0 to 10 degrees. The coated cermet tool formed by vapor deposition in the state of coexisting with the lower Ti compound layer, with the heat-transformed α-type (Al, Zr) ₂ O ₃ layer in which the highest peak appears as the upper layer of the hard coating layer, Compared to coated cermet tools, Fast intermittent cutting without chipping occurs cutting edge in, to become to exert more excellent wear resistance.
The research results shown in (a) to (c) above were obtained.

The present invention has been made based on the above research results, and on the surface of a tool base composed of a WC-based cemented carbide or TiCN-based cermet,
(A) The lower layer is composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer formed by chemical vapor deposition, and has a total average layer thickness of 3 to 20 μm. A Ti compound layer having
(B) the upper layer has a κ-type or θ-type crystal structure in the state of chemical vapor deposition, and
Composition _{formula: (Al 1-X Zr X} ) 2 O 3,
In the surface of the (Al, Zr) ₂ O ₃ layer, which is measured by an electron beam microanalyzer (EPMA) and the X value satisfies the atomic ratio of 0.003 to 0.05,
Composition formula: TiO _Y ,
The Ti oxide layer measured by an Auger spectroscopic analyzer and satisfying a Y value of 1.2 to 1.9 in terms of atomic ratio to Ti is an average layer thickness of 0.05 to 1.5 μm. In a state where chemical vapor deposition is formed, heat transformation treatment is performed to transform the crystal structure of the (Al, Zr) ₂ O ₃ layer having the κ-type or θ-type crystal structure into an α-type crystal structure,
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. The heating transformation α-type (Al, Zr) ₂ having a mean angle thickness of 1 to 15 μm, and showing a tilt angle frequency distribution graph in which the total frequency to be obtained accounts for 45% or more of the total frequency in the tilt angle frequency distribution graph O ₃ layer,
The hard coating layer formed by the hard coating layer configured as described above in (a) and (b) is characterized by a coated cermet tool that exhibits excellent chipping resistance.

Next, the reason why the constituent layers of the hard coating layer of the coated cermet tool of the present invention are numerically limited as described above will be described below.
(A) The average layer thickness of the lower layer (Ti compound layer) The Ti compound layer itself has excellent high-temperature strength, and the presence of the Ti compound layer makes the hard coating layer have high-temperature strength. The heat-transformed α-type (Al, Zr) ₂ O ₃ layer, which is the upper layer, adheres firmly to any of the layers, thus contributing to improving the adhesion of the hard coating layer to the tool substrate, but the total average layer thickness However, if the total average layer thickness exceeds 20 μm, thermoplastic deformation tends to occur particularly during high-speed intermittent cutting with high heat generation. Since it causes wear, the total average layer thickness is set to 3 to 20 μm.

(B) Ti oxide layer composition (Y value) and average layer thickness As described above, the Ti oxide layer is a vaporized κ-type or θ-type (Al, Zr) ₂ O ₃ layer heat-transformed α-type (Al, Zr). ) Heat transformation to the ₂ O ₃ layer is generated simultaneously on the entire surface, and cracks generated during the heat transformation are refined and uniformed. In addition, the heat transformation is promoted, and the crystal grain growth is achieved by shortening the processing time. Furthermore, the Ti oxide layer has a composition formula: TiO _{Y with} a Y value of 1.2 to 1.9 in terms of atomic ratio to Ti as described above. Correspondingly, the highest peak of the measured inclination angle appears in the inclination angle section range of 0 to 10 degrees in the inclination angle number distribution graph, and the frequency existing in the inclination angle section of 0 to 10 degrees The total ratio is 45% or more of the whole frequency in the slope angle distribution graph. That has the effect of showing the inclination angle frequency distribution graph, therefore, in the Y value is less than 1.2, the heating transformation α-type (Al, Zr) of 0 degrees inclination angle frequency distribution graph of the ₂ O ₃ layer The height of the peak appearing in the range is insufficient, that is, the total ratio of the frequencies existing in the range of 0 to 10 degrees is less than 45% of the total frequencies in the inclination angle frequency distribution graph. As described above, the heat-transformed α-type (Al, Zr) ₂ O ₃ layer cannot secure a desired excellent high-temperature strength, and as a result, a desired improvement effect in chipping resistance cannot be obtained. When the value exceeds 1.9, the slope angle section where the highest peak appears is out of the range of 0 to 10 degrees, and in this case as well, the heat transformation α-type (Al, Zr) ₂ O ₃ layer is excellent in the desired manner. Because high temperature strength cannot be secured, The Y value was defined as 1.2 to 1.9 in atomic ratio to Ti.
Further, in this case, when the average thickness of the Ti oxide layer is less than 0.05 μm, the above-mentioned action cannot be sufficiently exerted, while an average layer thickness of 1.5 μm is sufficient for the action, and more Therefore, the average layer thickness was determined to be 0.05 to 1.5 μm μm.

(C) Zr content and average layer thickness of upper layer [heat-transformed α-type (Al, Zr) ₂ O ₃ layer] The heat-transformed α-type (Al, Zr) ₂ O ₃ layer is composed of the constituent Al Excellent high temperature hardness and heat resistance due to the action, and high temperature strength due to the action of the same Zr, it will exhibit excellent wear resistance and chipping resistance, but the Zr content ratio (X value), If the atomic ratio (hereinafter the same) is less than 0.003 in the total amount with Al, a sufficient high-temperature strength improvement effect cannot be secured, while if the Zr content exceeds 0.05, Since the hexagonal crystal lattice is disturbed and it becomes difficult to satisfactorily transform from the κ-type or θ-type crystal structure to the α-type crystal structure in the heat transformation treatment, the content ratio of Zr (X value) Was determined to be 0.003 to 0.05.
If the average thickness of the heat-transformed α-type (Al, Zr) ₂ O ₃ layer is less than 1 μm, the hard coating layer cannot exhibit sufficient wear resistance, while the average layer thickness exceeds 15 μm. When the thickness is too thick, chipping is likely to occur. Therefore, the average layer thickness is set to 1 to 15 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 necessary, but the average layer thickness in this case may be 0.1 to 1 μm, This is because 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 with an average layer thickness of up to 1 μm.

The coated cermet tool of the present invention has an excellent heat-transformed α-type (Al, Zr) ₂ O ₃ layer that constitutes the upper layer of the hard coating layer even in high-speed intermittent cutting such as steel and cast iron with extremely high mechanical and thermal shock. Since it exhibits high temperature hardness and heat resistance, and excellent chipping resistance, the hard coating layer exhibits excellent wear resistance without occurrence of chipping.

  Next, the coated cermet 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 1 to 3 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 performing the processing, tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were manufactured.

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 a standard / CNMG12041 chip shape were formed.

Next, a normal chemical vapor deposition apparatus was used on the surfaces of the tool bases A to F and the tool bases a to f, and Table 3 (l-TiCN in Table 3 is described in JP-A-6-80.050). As the lower layer of the hard coating layer, the conditions for forming a TiCN layer having a vertically grown crystal structure are shown. Ti compound layers are vapor-deposited in the combinations shown in Table 5 and with the target layer thickness, and then (Al, Zr) ₂ O ₃ having a crystal structure of κ-type or θ-type under the same conditions shown in Table ₃ The layers are also formed by vapor deposition in the combinations shown in Table 5 and with the target layer thickness, and then a Ti oxide layer is formed on the surface of the vapor-deposited κ-type or θ-type (Al, Zr) ₂ O ₃ layer. Vapor deposition was carried out with the combinations shown in Table 5 under the conditions shown in In this state, this was subjected to a heat transformation treatment in a 30 kPa Ar atmosphere at a temperature of 1100 ° C. for a predetermined time within a range of 20 to 100 minutes, and the deposited κ-type or θ-type crystal structure ( Al, Zr) formation (Al of ₂ O ₃ layer a α-type crystal structure, Zr) ₂ O ₃ layer by transformation becomes heated transformation α type (Al, Zr) ₂ O ₃ layer as the upper layer of the hard coating layer By doing this, this invention coated cermet tool 1-13 was manufactured, respectively.

  In the production of the cermet tools 1 to 13 according to the present invention, a separate test piece is prepared, and the test piece is loaded into the chemical vapor deposition apparatus, and a Ti oxide layer is formed on the surface of the test piece. At that time, it was taken out from the apparatus, and the composition (Y value) and layer thickness of the Ti oxide layer were measured (longitudinal section measurement) using an Auger spectroscopic analyzer and a scanning electron microscope. As a result, all showed the composition and average layer thickness (average value of 5-point measurement) substantially the same as the target composition and target layer thickness.

For comparison purposes, as shown in Table 6, an evaporated α-type Al ₂ O ₃ layer having the target layer thickness shown in Table 6 is also formed as the upper layer of the hard coating layer under the same conditions as shown in Table 3. In addition, conventionally coated cermet tools 1 to 13 were produced under the same conditions except that the formation of the Ti oxide layer and the heat transformation treatment under the above conditions were not performed.

Next, the field-emission type scanning electrons of the heat-transformed α-type (Al, Zr) ₂ O ₃ layer and the vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the above-described coated cermet tool of the present invention and the conventional coated cermet tool Each pole plot graph was created using a microscope.
That is, the pole plot graph shows a mirror of a field emission scanning electron microscope in a state where the surfaces of the heat-transformed α-type (Al, Zr) ₂ O ₃ layer and the deposited α-type Al ₂ O ₃ layer are polished surfaces. Each crystal grain having a hexagonal crystal lattice existing in the measurement range of the surface polished surface is set in a cylinder, and an electron beam with an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees with an irradiation current of 1 nA. The surface of the crystal grain is the crystal plane of the surface polished surface with respect to the normal of the surface polished surface at an interval of 0.1 μm / step using an electron backscatter diffraction image apparatus (0001) ) The inclination angle formed by the normal of the surface is measured, and based on the measurement result, the measurement inclination angle within the range of 0 to 45 degrees is classified for each 0.25 degree pitch among the measurement inclination angles. And count the frequencies that exist in each category Ri was created.

In the inclination angle number distribution graphs of the various heat-transformed α-type (Al, Zr) ₂ O ₃ layers and vapor-deposited α-type Al ₂ O ₃ layers obtained as a result, the inclination angle segments in which the (0001) plane shows the highest peak, Tables 5 and 6 show the ratios of the number of inclination angles existing in the inclination angle section in the range of 0 to 10 degrees to the number of inclination angles in the entire inclination angle number distribution graph, respectively.

In the above-described various inclination angle number distribution graphs, as shown in Tables 5 and 6, each of the heat-transformed α-type (Al, Zr) ₂ O ₃ layers of the coated cermet tool of the present invention is measured on the (0001) plane. An inclination in which the highest peak appears in the inclination angle section where the inclination angle distribution is in the range of 0 to 10 degrees, and the ratio of the number of inclination angles existing in the inclination angle section in the range of 0 to 10 degrees is 45% or more. Whereas the angle distribution graph is shown, the vapor deposition α-Al ₂ O ₃ layers of the conventional coated cermet tools are all unbiased within the range of the measured inclination angle of the (0001) plane within the range of 0 to 45 degrees. The inclination angle number distribution graph in which the highest peak does not exist and the ratio of the inclination angle number existing in the inclination angle section within the range of 0 to 10 degrees is also 23% or less is shown.
2 is a graph showing the distribution of the number of inclination angles of the heat-transformed α-type (Al, Zr) ₂ O ₃ layer of the coated cermet tool 2 of the present invention, and FIG. 3 is the vapor-deposited α-type Al ₂ O ₃ of the conventional coated cermet tool 10. The graph of the distribution of the number of inclination angles of the layers is shown respectively.

Further, for the above-described coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analysis device (layer When the longitudinal cross section was observed), the former consisted of a Ti compound layer having substantially the same composition as the target composition and a heat-transformed α-type (Al, Zr) ₂ O ₃ layer, and the surface portion was subjected to heat transformation treatment. The presence of a Ti oxide layer formed by evaporation was also confirmed. On the other hand, it was confirmed that both of the latter consisted of a Ti compound having substantially the same composition as the target composition and a deposited α-type Al ₂ O ₃ layer. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated cermet tools was measured using a scanning electron microscope (same longitudinal section measurement), the average layer thickness (substantially the same as the target layer thickness) Average value of 5-point measurement) was shown.

Next, in the state where each of the various coated cermet tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13 are as follows.
Work material: JIS · SCM420 lengthwise equal four round grooved round bars,
Cutting speed: 450 m / min,
Incision: 1.5mm,
Feed: 0.3mm / rev,
Cutting time: 5 minutes
Dry high-speed intermittent cutting test of alloy steel under the conditions (normal cutting speed is 200 m / min),
Work material: JIS · S25C lengthwise equidistantly 4 vertical grooved round bars,
Cutting speed: 450 m / min,
Incision: 1.5mm,
Feed: 0.35mm / rev,
Cutting time: 5 minutes
Dry high-speed intermittent cutting test of carbon steel under the conditions (normal cutting speed is 250 m / min),
Work material: JIS / FC250 lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 500 m / min,
Incision: 1.5mm,
Feed: 0.3mm / rev,
Cutting time: 5 minutes
The dry high speed intermittent cutting test (normal cutting speed is 250 m / min) was performed on cast iron under the above conditions, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 7.

From the results shown in Tables 5 to 7, in the coated cermet tools 1 to 13 of the present invention, the upper layer of the hard coating layer is an inclination angle section within the range where the inclination angle of the (0001) plane is 0 to 10 degrees. Heat transformation α-type (Al, Zr) ₂ O ₃ layer showing the highest peak and showing an inclination angle number distribution graph in which the total ratio of the frequencies existing in the inclination angle range of 0 to 10 degrees occupies 45% or more The heat-transformed α-type (Al, Zr) ₂ O ₃ layer has excellent chipping resistance even in high-speed intermittent cutting of steel and cast iron with extremely high mechanical thermal shock and high heat generation. As a result, the occurrence of chipping at the cutting edge is remarkably suppressed and excellent wear resistance is exhibited, whereas the upper layer of the hard coating layer has a distribution of measured inclination angles on the (0001) plane of 0 to 45. Slope that is unbiased within the range of degrees and does not have the highest peak In the conventional coated cermet tools 1 to 13, which is composed of vapor-deposited α-Al ₂ O ₃ layer shows a frequency distribution graph, both the deposition α-Al ₂ O ₃ layer is the severe mechanical and thermal shock at high speed interrupted cutting It is obvious that chipping occurs at the cutting edge and the service life is reached in a relatively short time.

  As described above, the coated cermet tool of the present invention has excellent chipping resistance not only in continuous cutting and intermittent cutting under normal conditions such as various steels and cast iron, but also in high-speed intermittent cutting which is particularly severe cutting conditions. Since it exhibits excellent cutting performance over a long period of time, 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.

Is a schematic explanatory view showing the measurement range of the various heating transformation α-type (Al, Zr) crystal grains (0001) in ₂ O ₃ layer and deposition α type the Al ₂ O ₃ layer surface inclination angle of which constitutes the hard coating layer . It is an inclination angle number distribution graph of the (0001) plane of the heat transformation α type (Al, Zr) ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool 2 of the present invention. It is the inclination angle number distribution graph of the (0001) plane of the vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the conventional coated cermet tool 10.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) As a lower layer, each consists of one or two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer formed by chemical vapor deposition, And a Ti compound layer having a total average layer thickness of 3 to 20 μm,
(B) the upper layer has a κ-type or θ-type crystal structure in the state of chemical vapor deposition, and
Composition _{formula: (Al 1-X Zr X} ) 2 O 3,
In the surface of the Al—Zr oxide layer having an X value satisfying 0.003 to 0.05 in atomic ratio, as measured by an electron beam microanalyzer (EPMA),
Composition formula: TiO _Y ,
The Ti oxide layer measured by an Auger spectroscopic analyzer and satisfying a Y value of 1.2 to 1.9 in terms of atomic ratio to Ti is an average layer thickness of 0.05 to 1.5 μm. In the state where chemical vapor deposition is formed, a heat transformation treatment is performed to transform the crystal structure of the Al-Zr oxide layer having the κ-type or θ-type crystal structure into an α-type crystal structure,
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. The heat-transformed α-type Al—Zr oxide layer showing a tilt angle frequency distribution graph in which the total frequency to be applied accounts for 45% or more of the total frequency in the tilt angle frequency distribution graph and having an average layer thickness of 1 to 15 μm ,
A surface-coated cermet cutting tool having excellent chipping resistance due to the hard coating layer formed by the hard coating layer constituted of (a) and (b) above.

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