JP4529578B2 - Surface coated cermet cutting tool whose hard coating layer exhibits excellent chipping resistance in high speed heavy cutting - Google Patents

Description

In the present invention, particularly in a state in which an aluminum oxide layer (hereinafter referred to as an Al ₂ O ₃ layer) that is a constituent layer of a hard coating layer is thickened, various kinds of cutting work such as steel and cast iron can be performed at high speed. Even under heavy cutting conditions such as high cutting and high feed with high mechanical impact, the hard coating layer exhibits excellent chipping resistance, and therefore, no chipping (small chipping) occurs, and long-term The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent wear resistance.

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 consisting of one or two or more layers of carbonitride oxide (hereinafter referred to as TiCNO) layers and having an overall average layer thickness of 3 to 20 μm,
(B) An aluminum oxide layer having an average layer thickness of 1 to 12 μm and having an α-type crystal structure in a state of chemical vapor deposition (hereinafter referred to as vapor deposition α-type Al) ₂ O ₃ layer)
There is known a coated cermet tool formed by vapor-depositing a hard coating layer composed of (a) and (b) above, and this coated cermet tool can be used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is well known to be used.

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, it is formed by chemical vapor deposition in a medium temperature range of 700 to 950 ° C using a mixed gas containing organic carbonitrides as a reaction gas in a normal chemical vapor deposition apparatus, and vertically grown. It is also known to have a 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 remarkably improved. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work. Accordingly, the vapor deposited α-type Al ₂ O ₃ layer has a maximum thickness of 20 μm. Although it is necessary to increase the thickness of the film and the cutting process is further accelerated, there is a tendency to strongly demand cutting work under heavy cutting conditions such as high cutting and high feed, but in the conventional coated cermet tool described above, There is no problem when this is used for continuous cutting and interrupted cutting under normal conditions such as steel and cast iron, but especially when this is used under high speed heavy cutting conditions, vapor deposition that constitutes a hard coating layer. Since the high-temperature hardness and high-temperature strength of the α-type Al ₂ O ₃ layer are insufficient, wear progresses rapidly and chipping easily occurs, and the thick film of the vapor-deposited α-type Al ₂ O ₃ layer Chipping is one step higher Since the more likely to occur, at present, leading to a relatively short time service life.

In view of the above, the present inventors paid attention to a coated cermet tool in which the vapor-deposited α-type Al ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and particularly the vapor-deposited α-type Al ₂ O 3. As a result of research to improve chipping resistance of _three layers,
(A) The vapor-deposited α-type Al ₂ O ₃ layer as a hard coating layer of the above-described conventional coated cermet tool is generally used in 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: 950-1100 ° C.
Reaction atmosphere pressure: 6-13 kPa,
1 (a), (b) and FIG. 1 using the field emission scanning electron microscope for the deposited α-type Al ₂ O ₃ layer formed under the normal conditions. 2 (a) and (b), as schematically shown in the drawing, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the tool substrate surface is irradiated with an electron beam, 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. Of the measured inclination angles, 45 to 90 degrees and 0 to 45 degrees, respectively. When the measured inclination angle within the range is divided for each pitch of 0.25 degrees, and an inclination angle number distribution graph is created by summing up the frequencies existing in each division, FIG. 5 (measurement inclination angle: 45 to 45) is created. 90 degrees) and FIG. 6 (measurement tilt angle: 0 to 45 degrees), The distribution of the measured inclination angle of the (0001) plane is an unbiased inclination angle number distribution graph regardless of the range of 45 to 90 degrees and 0 to 45 degrees.

(B) On the other hand, the vapor-deposited α-type Al ₂ O ₃ layer was similarly used with a normal chemical vapor deposition device,
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,
As shown in FIG. 1, the deposited α-type Al ₂ O ₃ layer formed as a result is formed using a field emission scanning electron microscope as shown in FIG. As shown in (a) and (b), each crystal grain having a hexagonal crystal lattice that is also present in the measurement range of the polished surface parallel to the tool base surface is irradiated with an electron beam, 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, and the measurement inclination angle within the range of 45 to 90 degrees out of the measurement inclination angles is set to 0. 3. When divided into 25-degree pitches and represented by an inclination angle number distribution graph obtained by summing up the frequencies existing in each area, as shown in FIG. The highest peak appears and the test results show that When the reaction atmosphere pressure is changed within the range of 20 to 30 kPa as described above, the position at which the sharpest peak appears changes within the range of 75 to 85 degrees of the inclination angle section, and the 75 to 85 degrees The total of the frequencies existing in the range occupies a ratio of 45 to 65% of the entire frequency in the inclination angle distribution graph, and the inclination angle in the range of 75 to 85 degrees in the inclination angle distribution graph as a result. The vapor-deposited α-type Al ₂ O ₃ layer in which the highest peak of the section appears has a relatively high high-temperature hardness as compared with the vapor-deposited α-type Al ₂ O ₃ layer formed under normal conditions.

(C) Furthermore, the vapor-deposited α-type Al ₂ O ₃ layer was similarly used with 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,
If the reaction gas composition is adjusted to the reaction gas composition different from the reaction gas composition of the above normal conditions (the temperature and pressure of the reaction atmosphere are the same as the above normal conditions), this result is obtained. The formed deposited α-type Al ₂ O ₃ layer is also within the measurement range of the polished surface parallel to the tool base surface, as shown in FIGS. 2A and 2B, using a field emission scanning electron microscope. Irradiate each individual crystal grain having a hexagonal crystal lattice with an electron beam, and measure the inclination angle formed by the normal of the (0001) plane, which is the crystal plane of the crystal grain, with respect to the normal of the polished surface In addition, the measured inclination angle within the range of 0 to 45 degrees out of the measured inclination angles is divided into pitches of 0.25 degrees, and the inclination angle number distribution is obtained by counting the frequencies existing in each section. When represented in the graph, as illustrated in FIG. A sharp maximum peak appears at a specific position of the minute. According to the test results, when the reaction atmosphere pressure in the chemical vapor deposition apparatus is changed within the range of 6 to 10 kPa as described above, the position where the sharp maximum peak appears is It changes within the range of 5 to 15 degrees of the inclination angle section, and the total of the frequencies existing in the range of 5 to 15 degrees occupies a ratio of 45 to 65% of the total degrees in the inclination angle frequency distribution graph. to be, the results of the inclination angle frequency distribution 5-15 ° inclination highest peak appears depositing α-type the Al ₂ O ₃ layer sections in the range of the graph, deposited α-type Al ₂ O normal conditions forming the Compared to _three layers, it has relatively high temperature strength.

(D) Therefore, the vapor-deposited α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer whose lower layer is made of a Ti compound layer, is 35 to 65% of the average layer thickness of the entire Al ₂ O ₃ layer. The upper and lower layers consist of a lower layer and the remaining upper layer. When measuring the polished surface parallel to the surface of the tool substrate, the upper layer has the highest peak in the inclination angle range of 75 to 85 degrees. In addition, an inclination angle frequency distribution graph in which the total frequency within the range of 75 to 85 degrees occupies a ratio of 45 to 65% of the entire frequency in the inclination angle frequency distribution graph is shown. The highest peak exists in the inclination angle section within the range of -15 degrees, and the total of the frequencies existing within the range of 5-15 degrees represents a ratio of 45-65% of the total degrees in the inclination angle distribution graph. Deposition α showing a graph of the distribution of the number of tilt angles Coated cermet tool formed by composed of Al ₂ O ₃ layer is thicker since the deposition α type the Al ₂ O ₃ layer is provided with a relative excellent high-temperature hardness and high-temperature strength, especially 20μm in maximum layer thickness In this state, even if cutting is performed under high-speed heavy cutting conditions, the upper layer of the hard coating layer has a distribution of measured inclination angles on the (0001) plane within the range of 0 to 45 degrees and 45 to 90 degrees. Compared to conventional coated cermet tools composed of vapor-deposited α-type Al ₂ O ₃ layers showing an unbiased inclination angle number distribution graph, the hard coating layer has superior wear resistance over the long term without chipping. To come out.
The research results shown in (a) to (d) above were 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 an overall average layer thickness of 3 to 20 μm,
(B) a vapor-deposited α-type Al ₂ O ₃ layer whose upper layer has an average layer thickness of 4 to 20 μm;
In the coated cermet tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
The above-mentioned deposited α-type Al ₂ O ₃ layer has an upper and lower two-layer structure comprising a lower layer of 35 to 65% and a remaining upper layer in a ratio to the average layer thickness of the entire Al ₂ O ₃ layer. Using a scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the tool substrate surface is irradiated with an electron beam, and the normal to the polished surface is The inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured. Among the measured inclination angles, the upper layer is in the range of 45 to 90 degrees, and the lower layer is in the range of 0 to 45 degrees. When the measured tilt angle is divided into pitches of 0.25 degrees and the frequency existing in each section is tabulated, it is represented by a tilt angle number distribution graph.
(A) The upper layer of the vapor-deposited α-type Al ₂ O ₃ layer has the highest peak in the tilt angle section within the range of 75 to 85 degrees, and the total of the frequencies existing in the range of 75 to 85 degrees. Shows an inclination angle number distribution graph occupying a proportion of 45 to 65% of the entire frequency in the inclination angle number distribution graph,
(B) The lower layer of the deposited α-type Al ₂ O ₃ layer has the highest peak in the tilt angle section within the range of 5 to 15 degrees, and the sum of the frequencies existing within the range of 5 to 15 degrees. Is an inclination angle number distribution graph occupying a proportion of 45 to 65% of the entire frequency in the inclination angle number distribution graph,
The hard coating layer is characterized by a coated cermet tool that exhibits excellent chipping resistance in high-speed heavy cutting.

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 vapor-deposited α-type Al ₂ O ₃ layer, and allows the hard coating layer to have high temperature strength by its excellent high temperature strength, It adheres firmly to any of the vapor-deposited α-type Al ₂ O ₃ layers, and thus has the effect of contributing to the improvement of the adhesion of the hard coating layer to the tool substrate. On the other hand, if the average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation especially in high-speed cutting with high heat generation, which causes uneven wear. Was determined to be 3 to 20 μm.

(B) Evaporated α-type Al ₂ O ₃ layer (upper layer)
As described above, the highest peak position of the measured inclination angle in the inclination angle number distribution graph of the upper layer and the lower layer of the vapor deposition α-type Al ₂ O ₃ layer is changed by changing the reaction atmosphere pressure in the chemical vapor deposition apparatus. However, according to the test results, when the reaction atmosphere pressure is 20 to 30 kpa in the upper layer and 6 to 10 kPa in the lower layer, the highest peak is 75 to 85 degrees in the upper layer and 5 in the lower layer. The sum of the frequencies appearing in the inclination angle section within the range of -15 degrees and existing within the range of 75-85 degrees and 5-15 degrees is 45 to 45 of the entire frequency in the inclination angle frequency distribution graph in any case. An inclination angle number distribution graph occupying a ratio of 65% is shown. Therefore, even if the reaction atmosphere pressure deviates from the lower range, the However, the maximum peak position of the measured inclination angle is out of the range of 75 to 85 degrees and 5 to 15 degrees, respectively. In such a case, the desired excellent high temperature hardness and high temperature strength are provided. It is something that cannot be done.
In addition, the deposited α-type Al ₂ O ₃ layer has excellent high temperature hardness and high temperature strength due to the superior high temperature hardness of the upper layer and the superior high temperature strength of the lower layer. If the Al ₂ O ₃ layer accounts for less than 35% of the average layer thickness, the high-temperature strength rapidly decreases and chipping tends to occur. On the other hand, if the thickness exceeds 65%, the high-temperature hardness Since the wear progresses and the wear progresses, the thickness of the lower layer is determined to be 35 to 65% as a proportion of the average layer thickness of the entire Al ₂ O ₃ layer, and the rest is occupied by the upper layer. An upper and lower two-layer structure was adopted.
Furthermore, if the average layer thickness of the vapor-deposited α-type Al ₂ O ₃ layer is less than 4 μm, the excellent characteristics of this layer cannot be exhibited sufficiently, while if the average layer thickness exceeds 20 μm and becomes too thick. Since the chipping (small chipping) is likely to occur in the cutting edge part, the overall average layer thickness is determined to be 4 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.

The coated cermet tool of the present invention is a state in which the thickness of the vapor-deposited α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is increased, and various types of steel and cast iron can be cut at high speed. Even when performed under heavy cutting conditions such as high cutting and high feed with high mechanical impact, the deposited α-type Al ₂ O ₃ layer has excellent high-temperature hardness and high-temperature strength. It exhibits excellent wear resistance without occurrence of chipping, and can further extend the service life.

  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.

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.

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: 0.75%, Ar: 26.5%, H ₂ :remaining,
Reaction atmosphere temperature: 1020 ° C.
Reaction atmosphere pressure: a predetermined pressure within a range of 6 to 10 kPa,
The lower layer of the deposition α-type Al ₂ O ₃ layer, which is the upper layer, is formed by vapor deposition with the target layer thickness shown in Tables 4 and 5 under the reaction gas composition adjustment conditions of
(C) Furthermore, the reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 5%, HCl: 2%, H ₂ S: 0.15%, H ₂ : the rest,
Reaction atmosphere temperature: 850 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 20-30 kPa,
The coated cermet tools 1 to 13 of the present invention are manufactured by vapor-depositing the upper layer of the vapor-deposited α-type Al ₂ O ₃ layer, which is also the upper layer, with the target layer thicknesses shown in Tables 4 and 5 under the low temperature and high pressure conditions did.

For the purpose of comparison, the formation of a vapor-deposited α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer,
Reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 5%, HCl: 2%, H ₂ S: 0.15%, H ₂ : remaining,
Reaction atmosphere temperature: 1020 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 6 to 13 kPa,
The conventional coated cermet tools 1 to 13 were produced under the same conditions as those of the present invention coated cermet tools 1 to 13 except that the target layer thicknesses shown in Tables 6 and 7 were used.

Next, for the vapor deposition 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, using a field emission scanning electron microscope, Each inclination angle number distribution graph was created.
That is, the inclination angle number distribution graph shows that the upper and lower layers of the vapor-deposited α-type Al ₂ O ₃ layers of the coated cermet tools 1 to 13 of the present invention are respectively polished surfaces parallel to the tool base surface. In this state, each polishing 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 polishing surface with an irradiation current of 1 nA. Irradiate each crystal grain having a hexagonal crystal lattice existing in the range, and use an electron backscatter diffraction image apparatus to make a region of 30 × 50 μm normal to the polished surface at an interval of 0.1 μm / step. On the other hand, the inclination angle formed by the normal line of the (0001) plane which is the crystal plane of the crystal grain is measured, and based on the measurement result, the upper layer of the measurement inclination angle is 45 to 90 degrees, About the lower layer Was created by dividing the measured inclination angle in the range of 0 to 45 degrees into pitches of 0.25 degrees and counting the frequencies existing in each section.
In addition, for the deposited α-type Al ₂ O ₃ layers of the conventional coated cermet tools 1 to 13, an arbitrary polished surface parallel to the tool base surface is observed under the same conditions, and an inclination angle number distribution graph is displayed under the same conditions. Created.

In the inclination angle frequency distribution graph of the results obtained various deposition α type the Al ₂ O ₃ layer of, as shown in Tables 4-7, the present invention coated cermet tools 1 to 13 deposited α-type the Al ₂ O ₃ layer of In the upper layer and lower layer, the distribution of the measured inclination angle of the (0001) plane is such that the highest peak appears in the inclination angle section within the range of 75 to 85 degrees in the upper layer and 5 to 15 degrees in the lower layer, respectively. In contrast to the number distribution graph, the deposited α-type Al ₂ O ₃ layer of the conventional coated cermet tools 1 to 13 has a distribution of measured inclination angles on the (0001) plane in the range of 45 to 90 degrees and 0 to 45 degrees. The inclination angle number distribution graph in which the highest peak does not exist is shown.
Tables 4 to 7 show the total inclinations present in the inclination angle sections in the range of 75 to 85 degrees and 5 to 15 degrees, respectively, in the inclination angle number distribution graphs of the various deposited α-type Al ₂ O ₃ layers. The ratio of the number of angles to the entire inclination angle number distribution graph is shown.
3 is an inclination angle number distribution graph of the upper layer of the deposited α-type Al ₂ O ₃ layer of the coated cermet tool 1 of the present invention, FIG. 4 is an inclination angle number distribution graph of the lower layer, and FIGS. the inclination angle frequency distribution graph, respectively showing the inclination angle segment of 45 to 90 degrees and 0 to 45 degrees of the coated cermet tools 1 deposition α type the Al ₂ O ₃ layer.

  Moreover, when the thickness of the constituent layer of the hard coating layer of the present invention 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 · SCM430 lengthwise equidistant 4 round bars with vertical grooves,
Cutting speed: 330 m / min. ,
Cutting depth: 1.0 mm,
Feed: 0.5 mm / rev. ,
Cutting time: 5 minutes
Dry interrupted high-speed high-feed cutting test of alloy steel under the following conditions (referred to as cutting condition A) (normal cutting speed and feed are 200 m / min. And 0.3 mm / rev.),
Work material: JIS / FC250 round bar,
Cutting speed: 400 m / min. ,
Cutting depth: 3.0 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 minutes
A dry continuous high-speed, high-cut cutting test of cast iron under the conditions (cutting condition B) (normal cutting speed and cutting is 300 m / min. And 1.5 mm),
Work material: JIS / S30C round bar,
Cutting speed: 350 m / min. ,
Incision: 2.5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes
The dry continuous high-speed, high-cut cutting test (normal cutting speed and cutting is 250 m / min. And 1.5 mm) of carbon steel under the above conditions (referred to as cutting condition C). The wear width was measured. The measurement results are shown in Table 8.

From the results shown in Tables 4 to 8, the coated cermet tools 1 to 13 of the present invention are the upper layer and lower layer of the upper and lower two-layer structure of the vapor-deposited α-type Al ₂ O ₃ layer that is the upper layer of the hard coating layer. In each of the inclination angle distribution graphs of the (0001) plane, the highest layer shows the highest peak in the inclination angle range of 75 to 85 degrees and the lower layer in the range of 5 to 15 degrees. Since it has strength, the cutting process of steel and cast iron is performed at high speed and with high mechanical impact in the state where the thickness of the deposited α-type Al ₂ O ₃ layer is increased. Even when performed under high speed heavy cutting conditions, chipping does not occur and excellent wear resistance is exhibited, whereas the entire upper layer of the hard coating layer has a measured inclination angle distribution of (0001) plane of 45 to 90 degrees. And a tilt that is unbiased within the range of 0 to 45 degrees and does not have the highest peak In the conventional coated cermet tools 1 to 13, which is composed of vapor-deposited α-type the Al ₂ O ₃ layer showing the angle frequency distribution graph, both in high-temperature hardness and high-temperature strength insufficient cause the deposition α type the Al ₂ O ₃ layer, It is clear that under high speed heavy cutting conditions, chipping occurs in the hard coating layer and the service life is reached in a relatively short time.

  As described above, the coated cermet tool of the present invention has excellent wear resistance without occurrence of chipping even in continuous cutting and interrupted cutting under normal conditions such as various steels and cast irons, especially in high-speed heavy cutting. 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 diagram illustrating a measurement range of the inclination angle in the case of measuring the crystal grains (0001) plane in the upper layer of vapor-deposited α-type the Al ₂ O ₃ layer constituting the hard coating layer. It is a schematic diagram illustrating a measurement range of the inclination angle in the case of measuring the crystal grains (0001) plane in the lower layer of the deposited α-type the Al ₂ O ₃ layer constituting the hard coating layer. It is an inclination angle number distribution graph of the (0001) plane of the upper layer of the vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool 1 of the present invention. It is an inclination angle number distribution graph of the (0001) plane of the lower layer of the vapor deposition α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool 1 of the present invention. The inclination angle frequency distribution graph showing the tilt angle sections of 45 to 90 degrees prior coated cermet deposited α-type constituting the hard layer of the tool 1 Al ₂ O ₃ layer (0001) plane. The inclination angle frequency distribution graph showing the tilt angle sections of 0 to 45 degrees of conventional coated cermet deposited α-type constituting the hard layer of the tool 1 Al ₂ O ₃ layer (0001) plane.

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 has an overall average of 3 to 20 μm. A Ti compound layer having a layer thickness,
(B) an aluminum oxide layer whose upper layer has an α-type crystal structure in the state of chemical vapor deposition and has an average layer thickness of 4 to 20 μm;
In the surface-coated cermet cutting tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
The aluminum oxide layer has an upper and lower two-layer structure composed of a lower layer of 35 to 65% and a remaining upper layer in a ratio of the average thickness of the entire aluminum oxide layer, and further using a field emission scanning electron microscope, A crystal grain having a hexagonal crystal lattice existing within a measurement range of a polished surface parallel to the tool substrate surface is irradiated with an electron beam, and the crystal plane of the crystal grain is normal to the polished surface. The inclination angle formed by the normal of the (0001) plane is measured, and the measurement inclination angle is within the range of 45 to 90 degrees for the upper layer and 0 to 45 degrees for the lower layer. When it is divided into pitches of 0.25 degrees and represented by an inclination angle number distribution graph obtained by counting the frequencies existing in each section,
(A) In the upper layer of the aluminum oxide layer, the highest peak exists in the inclination angle section in the range of 75 to 85 degrees, and the total of the frequencies existing in the range of 75 to 85 degrees is the inclination angle number. The inclination angle frequency distribution graph which occupies the ratio of 45 to 65% of the whole frequency in a distribution graph is shown,
(B) In the lower layer of the aluminum oxide layer, the highest peak exists in the inclination angle section in the range of 5 to 15 degrees, and the total of the frequencies existing in the range of 5 to 15 degrees is the inclination angle number. Showing an inclination angle frequency distribution graph occupying a proportion of 45 to 65% of the total frequency in the distribution graph;
A surface-coated cermet cutting tool that features a hard coating layer that exhibits excellent chipping resistance in high-speed heavy cutting.

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