JP4518259B2 - A surface-coated cermet cutting tool that exhibits excellent chipping resistance with a hard coating layer in high-speed intermittent cutting - Google Patents

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 first layer, a chemical vapor deposition formed titanium nitride (hereinafter referred to as TiN) layer and titanium carbonitride (hereinafter referred to as TiCN) layer, or a laminate of both layers, and A first adhesive bonding layer having an average layer thickness of 0.1 to 1 μm;
(B) The second layer is formed by chemical vapor deposition,
Composition formula: (Ti _1-X Zr _X ) CN (wherein X is 0.02 to 0.15 in atomic ratio),
A high-temperature strengthening layer comprising a composite carbonitride of Ti and Zr satisfying the following [hereinafter referred to as (Ti, Zr) CN] layer and having an average layer thickness of 2.5 to 15 μm;
(C) As the third layer, either a titanium carbonate (hereinafter referred to as TiCO) layer formed by chemical vapor deposition or a titanium carbonitride oxide (hereinafter referred to as TiCNO) layer, or a laminate of both layers is formed. And a second adhesive bonding layer having an average layer thickness of 0.1 to 1 μm,
(D) As a fourth layer, a high-temperature hard layer comprising an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer formed by chemical vapor deposition and having an average layer thickness of 1 to 15 μm,
A coated cermet tool formed by forming a hard coating layer composed of (a) to (d) 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
JP 2001-11632 A

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. When used for high-speed intermittent cutting in which mechanical impact is repeatedly applied at an extremely short pitch, the hard coating layer constituting this has high-temperature hardness and heat resistance due to the fourth Al ₂ O ₃ layer, The high temperature strength of the second layer of (Ti, Zr) CN due to the high temperature strengthening layer is insufficient, so that it cannot respond satisfactorily to the mechanical shock. As a result, the hard coating layer has Chi Since the ring (small chipping) tends to occur, at present, leading to a relatively short time service life.

In view of the above, the inventors of the present invention have (Ti, Zr) CN as a second high-temperature strengthening layer in order to improve the chipping resistance of the hard coating layer of the coated cermet tool. Layer, that is, excellent heat resistance due to the inclusion of the Zr component, relatively high high-temperature strength due to the inclusion of the Ti component, and as schematically shown in FIG. 1A, Ti, Zr, carbon, Focusing on the (Ti, Zr) CN layer having a NaCl-type cubic crystal structure in which constituent atoms composed of nitrogen and nitrogen are present (FIG. 1 (b) shows a state cut along the (011) plane), As a result of research,
(A) A (Ti, Zr) CN layer (hereinafter referred to as a conventional (Ti, Zr) CN layer) which is a second high-temperature strengthened layer (hereinafter referred to as a conventional high-temperature strengthened layer) constituting a hard coating layer of a conventional coated cermet tool For example, in a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, TiCl 4: 1~5%,} ZrCl 4: 0.1~1%, CH 3 CN: 0.6~5%, N 2: 25~45%, H 2: remainder,
Reaction atmosphere temperature: 750-980 ° C.
Reaction atmosphere pressure: 2.7 to 13.5 kPa,
It is formed by vapor deposition under the conditions (called normal conditions).
Reaction gas composition: by _{volume%, TiCl 4: 20~30%,} ZrCl 4: 0.5~4%, CH 3 CN: 5~10%, CH 4: 0.5~5%, N 2: 35~ 50%, H ₂ : remaining,
Reaction atmosphere temperature: 1000 to 1050 ° C.
Reaction atmosphere pressure: 6-20 kPa,
In other words, in the reaction gas composition, TiCl ₄ and CH ₃ CN are relatively high and CH ₄ gas is newly added to further increase the ambient temperature. When vapor deposition is performed under (reactive gas composition adjustment high temperature conditions), the (Ti, Zr) CN layer (hereinafter referred to as a modified (Ti, Zr) CN layer) formed under the resultant reaction gas composition adjustment high temperature conditions has a high temperature strength. Is further improved and has excellent mechanical impact resistance, the coated cermet tool in which the second layer of the hard coating layer is composed of the modified (Ti, Zr) CN layer is particularly suitable. The hard coating layer exhibits excellent chipping resistance even in high-speed intermittent cutting with severe mechanical impact, and exhibits excellent wear resistance over a long period of time.

(B) About the conventional (Ti, Zr) CN layer and the modified (Ti, Zr) CN layer of (a), which constitute the second layer of the hard coating layer of the conventional coated cermet tool,
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams of FIGS. 2A and 2B, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the electron back Using a scattering diffraction image apparatus, the method of the (001) plane and the (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the surface-polished surface in a predetermined region at an interval of 0.1 μm / step The tilt angle formed by the line (in FIG. 2a, when the tilt angle of the (001) plane is 0 degree and the tilt angle of the (011) plane is 45 degrees, the (001) plane of FIG. The inclination angle is 45 degrees, and the inclination angle of the (011) plane is 0 degree. All inclination angles of the crystal grains including these angles are measured. In this case, the crystal grains are , NaC as lattice points of the Ti, Zr, carbon, and the constituent atoms consisting of nitrogen present, respectively It has a crystal structure of the type cubic sharing based on the measurement inclination angle result obtained, at the interface of the crystal grains adjacent to each other, one of constituent atoms respectively between the crystal grains mutually the constituent atoms The distribution of lattice points (constituent atom shared lattice points) to be calculated is calculated , and the number of lattice points that do not share constituent atoms existing between the constituent atom shared lattice points: N (in this case, N is a NaCl-type cubic crystal) The distribution ratio of each constituent atom shared lattice point form (unit form) represented by ΣN + 1 determined for each structure is an even number of 2 or more, but N: 28 is the upper limit from the point of distribution frequency) , Σ3 to Σ29, the distribution ratio of each unit form as a percentage of the total distribution ratio of the whole unit form of Σ3 to Σ29, when creating a constituent atom shared lattice point distribution graph , any (Ti, Zr) CN layer is also the best for Σ3 In the conventional (Ti, Zr) CN layer, as shown in FIG. 4, the distribution ratio of Σ3 is 30% or less. On the other hand, the modified (Ti, Zr) CN layer, as illustrated in FIG. 3, shows a very high constituent atom sharing lattice distribution graph in which the distribution ratio of Σ3 is 60 to 80%. The ratio varies depending on the content of TiCl ₄ and CH ₃ CN constituting the reaction gas, CH ₄ , and the atmospheric reaction temperature.

(C) The modified (Ti, Zr) CN layer is higher than the conventional (Ti, Zr) CN layer in addition to the high temperature strength and heat resistance of the (Ti, Zr) CN itself. Since it has high-temperature strength, the coated cermet tool formed by vapor deposition as a high-temperature reinforcing layer (hereinafter also referred to as a modified high-temperature reinforcing layer) constituting the second layer of the hard coating layer is the fourth high-temperature hard layer. Combined with the excellent high-temperature hardness and heat resistance of the Al ₂ O ₃ layer that constitutes, particularly, the cutting edge is subjected to repeated mechanical impacts at a very short pitch, for example, cutting speeds of 420 m / min and 440 m The conventional (Ti, Zr) is also used for high- speed intermittent cutting of / min (described in the examples) and when the intermittent cutting is performed under heavy cutting conditions such as high cutting and high feed. ) Evaporate CN layer That in comparison with the conventional coated cermet tool, it becomes to exhibit chipping resistance of the hard coating layer is more excellent.
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) First adhesion formed by chemical vapor deposition, either TiN layer or TiCN layer, or a laminate of both layers, and having an average layer thickness of 0.1 to 1 μm. The bonding layer (b) is formed by chemical vapor deposition as the second layer,
Composition formula: (Ti _1-X Zr _X ) CN (wherein X is 0.02 to 0.15 in atomic ratio),
A high-temperature strengthening layer comprising a (Ti, Zr) CN layer satisfying the following conditions and having an average layer thickness of 2.5 to 15 μm:
(C) as a third layer, a second adhesion bonding layer comprising either a TiCO layer and a TiCNO layer formed by chemical vapor deposition, or a laminate of both layers, and having an average layer thickness of 0.1 to 1 μm;
(D) As the fourth layer, a high-temperature hard layer comprising an Al ₂ O ₃ layer formed by chemical vapor deposition and having an average layer thickness of 1 to 15 μm,
In the coated cermet tool formed with the hard coating layer composed of (a) to (d) above,
The high-temperature strengthening layer, which is the second layer of the hard coating layers, is also formed by chemical vapor deposition, and has the composition formula: (Ti _1-X Zr _X ) CN (wherein X is 0.02 to 0.00 in terms of atomic ratio). 15), and further having an average layer thickness of 2.5 to 15 μm,
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and an electron backscatter diffraction image apparatus is used to set a predetermined region at an interval of 0.1 μm / step. The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, is measured with respect to the normal line of the surface-polished surface. It has a NaCl-type cubic crystal structure in which constituent atoms composed of Ti, Zr, carbon, and nitrogen exist, respectively, and based on the measured tilt angle obtained as a result, at the interface between crystal grains adjacent to each other, A lattice in which each constituent atom calculates a distribution of lattice points (constituent atom shared lattice points) that share one constituent atom among the crystal grains and does not share constituent atoms that exist between the constituent atom shared lattice points Number of points: N (in this case N is an even number of 2 or more due to the crystal structure of the NaCl type cubic crystal, but the constituent atomic shared lattice point form (unit form) represented by ΣN + 1 defined for each distribution frequency (N: 28 is the upper limit) In the constituent atomic shared lattice distribution graph showing the distribution ratio of each unit form of Σ3 to Σ29 as a ratio of the total distribution ratio of the whole unit form of Σ3 to Σ29, Σ3 is calculated. A modified (Ti, Zr) CN layer showing a constituent atom shared lattice point distribution graph in which the highest peak exists and the distribution ratio of Σ3 accounts for 60 to 80% of the total distribution ratio of the whole unit form ;
It is characterized by a coated cermet tool that exhibits excellent chipping resistance with a hard coating layer in high-speed intermittent cutting.

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) First adhesion bonding layer The TiN layer and the TiCN layer constituting the first adhesion bonding layer are firmly bonded to both the tool base and the modified (Ti, Zr) CN layer as the second layer, Therefore, although it has the effect | action which contributes to the tight bondability improvement with respect to the tool base | substrate of a hard coating layer, if the average layer thickness is less than 0.1 micrometer, desired outstanding close bondability cannot be ensured, but close contact bondability Can be sufficiently secured with an average layer thickness of 1 μm, the average layer thickness was determined to be 0.1 to 1 μm.

(B) Modified high-temperature strengthened layer The distribution ratio of Σ3 in the constituent atomic shared lattice distribution graph of the modified (Ti, Zr) CN layer constituting the modified high-temperature strengthened layer that is the second layer of the hard coating layer is as described above. As shown in FIG. _4, the TiCl ₄ and CH ₃ CN constituting the reaction gas, the content of CH ₄ and the atmospheric reaction temperature can be adjusted to 60 to 80%. In this case, the distribution ratio of Σ3 is 60%. If the ratio is less than 1, it is not possible to ensure the excellent high-temperature strength improvement effect that does not cause chipping in the hard coating layer in the high-speed intermittent cutting process. Therefore, the higher the distribution ratio of Σ3, the better, but the distribution ratio of Σ3 Since it is difficult to form a layer exceeding 80%, the distribution ratio of Σ3 is set to 60 to 80%. As described above, the modified (Ti, Zr) CN layer has a further superior high-temperature strength in addition to the high-temperature strength and heat resistance of (Ti, Zr) CN itself as described above. If the average layer thickness is less than 2.5 μm, the desired excellent high-temperature strength improvement effect cannot be sufficiently provided to the hard coating layer. On the other hand, if the average layer thickness exceeds 15 μm, the thermoplasticity causes uneven wear. Since deformation tends to occur and wear accelerates, the average layer thickness is set to 2.5 to 15 μm.
Further, as described above, the Zr component in the modified (Ti, Zr) CN layer has an effect of improving heat resistance and suppressing softening in a high-temperature atmosphere during cutting. If the value is an atomic ratio occupying the total amount of Ti and less than 0.02, the desired heat resistance improvement effect cannot be obtained. On the other hand, if the X value exceeds 0.15, the high temperature strength tends to decrease. Therefore, the X value indicating the content ratio of Zr was determined to be 0.02 to 0.15.

(C) Second adhesion bonding layer The TiCO layer and the TiCNO layer constituting the second adhesion bonding layer are either a modified (Ti, Zr) CN layer that is a _second layer or an Al ₂ O ₃ layer that is a high-temperature hard layer. In addition, it has an effect of improving the tight bondability of the hard coating layer to the tool substrate, and if the average layer thickness is less than 0.1 μm, the desired excellent close bondability is ensured. On the other hand, since the tight adhesion can be sufficiently secured with an average layer thickness of 1 μm, the average layer thickness was determined to be 0.1 to 1 μm.

(D) High-temperature hard layer The Al ₂ O ₃ layer constituting the high-temperature hard layer has excellent high-temperature hardness and heat resistance, and contributes to improving the wear resistance of the hard coating layer, but the average layer thickness is less than 1 μm. In this case, the hard coating layer cannot exhibit sufficient wear resistance. On the other hand, if the average layer thickness exceeds 15 μm, chipping is likely to occur. It was determined to be 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 is a modified (Ti, Zr) CN layer (modified high-temperature strengthened layer) that is the second 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. However, it has excellent high-temperature strength and exhibits excellent chipping resistance, and thus exhibits excellent wear resistance over a long period of time without occurrence of chipping in the hard coating layer.

  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 defined in ISO · CNMG12041 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 is used on the surfaces of the tool bases A to F and the tool bases a to f, and first, a first adhesive bonding layer made of either a TiN layer or a TiCN layer, or a laminate of both. Are formed under the conditions shown in Table 3 with the target layer thickness shown in Table 5, and then the modified (Ti, Zr) CN layer (modified high-temperature strengthened layer) is formed under the conditions shown in Table 4. Then, a second adhesion bonding layer composed of one or both of a TiCO layer and a TiCNO layer is formed under the conditions shown in Table 3, and the target layer thickness shown in Table 5 is formed. Then, the coated cermet tools 1 to 13 of the present invention are formed by vapor-depositing the Al ₂ O ₃ layer (high-temperature hard layer) with the target layer thickness shown in Table 5 under the same conditions as shown in Table 3. Each was manufactured.

For comparison purposes, as shown in Table 6, a conventional hard coating layer (Ti, Zr) in which the second layer of the hard coating layer is formed by vapor deposition under the conditions shown in Table 4 and with the target layer thicknesses shown in Table 6. Conventionally coated cermet tools 1 to 13 are manufactured by vapor-depositing a first adhesive bonding layer, a second adhesive bonding layer, and an Al ₂ O ₃ layer (high-temperature hard layer) under the same conditions except for the CN layer. did.

Subsequently, the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer constituting the hard coating layer of the above-described coated cermet tool of the present invention and the conventional coated cermet tool are examined using a field emission scanning electron microscope. Each component atom shared lattice distribution graph was created.
That is, the constituent atomic shared lattice point distribution graph shows a mirror of a field emission scanning electron microscope in a state where the surfaces of the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer are polished surfaces. An electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polished surface with an irradiation current of 1 nA to each crystal grain existing within the measurement range of the surface polished surface. Using a backscatter diffraction image apparatus, a (001) plane and a (011) plane that are crystal planes of the crystal grains with respect to the normal line of the surface-polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step. The inclination angle formed by the normal of the surface is measured, and based on the measurement inclination angle obtained as a result, each of the constituent atoms is one constituent atom between the crystal grains at the interface between adjacent crystal grains. Shared lattice points (constituent atom shared lattice points Calculates the distribution, the number of lattice points not sharing the constituent atom exist between the constituent atom covalent lattice point: N (in this case, N represents but an even number on more than one crystal structure of NaCl type cubic, Each distribution ratio of the constituent atom shared lattice point form (unit form) represented by ΣN + 1 determined for each distribution frequency (with N: 28 as the upper limit) is calculated, and each unit form of Σ3 to Σ29 is calculated. The distribution ratio was created by calculating the ratio of the total unit ratio of the above Σ3 to Σ29 .

  In the constituent atomic shared lattice distribution graphs of the various modified (Ti, Zr) CN layers and conventional (Ti, Zr) CN layers obtained as a result, the entire ΣN + 1 (N is all even numbers in the range of 2 to 28). Table 7 shows the distribution ratio of Σ3.

In the above-mentioned various constituent atomic share lattice point distribution graphs, as shown in Table 7, all of the modified (Ti, Zr) CN layers of the coated cermet tool of the present invention have a distribution ratio of 60 to 80% of Σ3. In contrast to a certain constituent atomic shared lattice distribution graph, the conventional (Ti, Zr) CN layer of the conventional coated cermet tool shows a constituent atomic shared lattice distribution graph in which the distribution ratio of Σ3 is 30% or less. It was a thing.
FIG. 3 is a graph showing the distribution of constituent atomic lattice points of the modified (Ti, Zr) CN layer of the coated cermet tool 1 of the present invention, and FIG. 4 is a graph of the conventional (Ti, Zr) CN layer of the conventional coated cermet tool 1. The constituent atom shared lattice point distribution graphs are respectively shown.

  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 section was observed), it was confirmed that both the former and the latter had substantially the same composition as the target composition. 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) The 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 / SS330 lengthwise equidistant 4 round bars with flutes,
Cutting speed: 440 m / min,
Incision: 1.5mm,
Feed: 0.25mm / rev,
Cutting time: 10 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 220 m / min) of mild steel under the above conditions (cutting condition A),
Work material: JIS / SUS303 lengthwise equidistant four round grooved round bars,
Cutting speed: 420 m / min,
Cutting depth: 1.3 mm,
Feed: 0.20mm / rev,
Cutting time: 10 minutes,
Dry high-speed intermittent cutting test of stainless steel under the above conditions (cutting condition B) (normal cutting speed is 200 m / min),
Work material: JIS / S10C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 420 m / min,
Cutting depth: 2.0 mm
Feed: 0.28mm / rev,
Cutting time: 10 minutes,
The dry high-speed intermittent cutting test (normal cutting speed is 220 m / min) of carbon steel under the above conditions (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 7.

  From the results shown in Tables 5 to 7, all of the coated cermet tools 1 to 13 of the present invention are constituent atomic shared lattice point distribution graphs in which the second layer configuration of the hard coating layer is 60 to 80% of Σ3 distribution ratio. The modified (Ti, Zr) CN layer has excellent high-temperature strength even in high-speed intermittent cutting of various steels, which are composed of the modified (Ti, Zr) CN layer shown and have extremely high mechanical impact. Since it exhibits chipping resistance, the occurrence of chipping in the hard coating layer is remarkably suppressed and excellent wear resistance is exhibited, whereas the second layer of the hard coating layer has a Σ3 distribution ratio of 30% or less. In the conventional coated cermet tools 1 to 13 composed of the conventional (Ti, Zr) CN layer showing the constituent atomic shared lattice point distribution graph, the mechanical impact resistance of the hard coating layer is insufficient with high-speed intermittent cutting. To be hard It is clear that chipping occurs in the covering layer and the service life is reached in a relatively short time.

  As described above, the coated cermet tool of the present invention has a hard coating layer not only for continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, but also for high-speed interrupted cutting that particularly requires high high-temperature strength. Because it shows excellent chipping resistance and exhibits excellent cutting performance over a long period of time, it can sufficiently satisfy the high performance of cutting equipment, labor saving and energy saving of cutting processing, and further cost reduction. Is.

It is a schematic view showing the crystal structure of NaCl type elevational cubic crystal constituting the second layer of the hard coating layer (Ti, Zr) CN layer has. It is a schematic explanatory drawing which shows the measurement aspect of the inclination angle of the (001) plane of a crystal grain and the (011) plane in the (Ti, Zr) CN layer which comprises the 2nd layer of a hard coating layer. 4 is a constituent atomic shared lattice point distribution graph of a modified (Ti, Zr) CN layer constituting the second layer of the hard coating layer of the coated cermet tool 1 of the present invention. 4 is a constituent atomic shared lattice point distribution graph of a conventional (Ti, Zr) CN layer constituting the second layer of the hard coating layer of the conventional coated cermet tool 1.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) As the first layer, a first adhesion having an average layer thickness of 0.1 to 1 μm, which is composed of any one of a titanium nitride layer and a titanium carbonitride layer formed by chemical vapor deposition, or a laminate of both layers. Bonding layer,
(B) The second layer is formed by chemical vapor deposition,
Composition formula: (Ti _1-X Zr _X ) CN (wherein X is 0.02 to 0.15 in atomic ratio),
A high-temperature strengthened layer comprising a composite carbonitride layer of Ti and Zr that satisfies the following conditions and having an average layer thickness of 2.5 to 15 μm;
(C) As the third layer, the first layer is composed of either a titanium carbonate layer formed by chemical vapor deposition or a titanium carbonitride oxide layer, or a laminate of both layers, and has an average layer thickness of 0.1 to 1 μm. 2 adhesive bonding layers,
(D) As the fourth layer, a high-temperature hard layer comprising an aluminum oxide layer formed by chemical vapor deposition and having an average layer thickness of 1 to 15 μm,
In the surface-coated cermet cutting tool formed by forming the hard coating layer composed of (a) to (d) above,
The high-temperature strengthening layer, which is the second layer of the hard coating layers, is also formed by chemical vapor deposition, and has the composition formula: (Ti _1-X Zr _X ) CN (wherein X is 0.02 to 0.00 in terms of atomic ratio). 15), and further having an average layer thickness of 2.5 to 15 μm,
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and an electron backscatter diffraction image apparatus is used to set a predetermined region at an interval of 0.1 μm / step. , The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the surface-polished surface is measured. It has a NaCl-type cubic crystal structure in which constituent atoms composed of Zr, carbon, and nitrogen are present, and the constituent atoms are formed at the interface between adjacent crystal grains based on the measured tilt angle. Calculate the distribution of lattice points that share one constituent atom between the crystal grains (constituent atom shared lattice points), and lattice points that do not share constituent atoms that exist between the constituent atom shared lattice points. Number: N (in this case N is an even number of 2 or more due to the crystal structure of the NaCl type cubic crystal, but the constituent atomic shared lattice point form (unit form) represented by ΣN + 1 defined for each distribution frequency (N: 28 is the upper limit) In the constituent atomic shared lattice distribution graph showing the distribution ratio of each unit form of Σ3 to Σ29 as a ratio of the total distribution ratio of the whole unit form of Σ3 to Σ29, Σ3 is calculated. A titanium carbonitride layer showing a constituent atomic shared lattice distribution graph in which the highest peak exists and the distribution ratio of Σ3 accounts for 60 to 80% of the total distribution ratio of the whole unit form ;
A surface-coated cermet cutting tool that exhibits excellent chipping resistance with a high hard coating layer in high-speed intermittent cutting.

Images