JP4822120B2 - Surface-coated cutting tool whose hard coating layer exhibits excellent chipping resistance in high-speed heavy cutting - Google Patents

Description

  The present invention provides a hard coating even when various materials such as steel and cast iron are machined under high feed, high cutting and high cutting speed conditions with high heat generation and high load on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping 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 upper layer having an average layer thickness of 1 to 15 μm, and an aluminum oxide (hereinafter referred to as α-type Al ₂ O ₃ ) layer having an α-type crystal structure in a state of chemical vapor deposition;
A coated tool formed by vapor-depositing the hard coating layer constituted by (a) and (b) above is known, and this coated tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. This is also well known.

  Further, in the above-mentioned coated tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and the TiCN layer constituting the Ti compound layer as the lower layer is used for the purpose of improving the strength of the layer itself. In a normal chemical vapor deposition apparatus, a gas mixture containing organic carbonitride is used as a reaction gas, and it is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. so as to have a vertically grown crystal structure. It is also known.

Furthermore, the α-type Al ₂ O ₃ layer constituting the hard coating layer of the above coated tool is a crystal grain having a crystal structure of a corundum type hexagonal close-packed crystal in which constituent atoms composed of Al and oxygen are present at lattice points. It is also known to be composed.
Japanese Unexamined Patent Publication No. 6-31503 Japanese Patent Laid-Open No. 6-8010

In recent years, the performance of cutting equipment has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and along with this, cutting tends to be faster. For tools, there is no problem when this is used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron, but this is accompanied by high heat generation and high load on the cutting edge. high feed, when used to perform fast heavy cutting conditions of a high cut, because the high temperature strength of the α type the Al ₂ O ₃ layer constituting the hard coating layer is not sufficient, the hard coating layer chipping As a result, the service life is reached in a relatively short time.

In view of the above, the present inventors have focused on the coated tool in which the α-type Al ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and in particular, has improved the high-temperature strength of the hard coating layer. As a result of research conducted,
(A) The α-type Al ₂ O ₃ layer as the upper layer constituting the hard coating layer of the conventional coated tool has excellent high-temperature hardness and heat resistance, and this layer can be used, for example, in an ordinary chemical vapor deposition apparatus. And
Reaction gas composition: volume%, AlCl ₃ : 2 to 4%, CO ₂ : 3 to 8%, HCl: 1.5 to 3%, H ₂ S: 0.05 to 0.2%, H ₂ : remaining ,
Reaction atmosphere temperature: 950-1100 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
Are deposited on a Ti compound layer (the lower layer of a conventional coated tool) under the above conditions (referred to as normal conditions). Such a Ti compound layer (lower layer) and an α-type Al ₂ O ₃ layer (upper layer) As described above, the hard coating layer made of is not provided with high-temperature strength and chipping resistance that can be sufficiently satisfied in high-speed heavy cutting.

(B) Therefore, the vapor deposition conditions are changed. First, on a Ti compound layer (lower layer), with a normal chemical vapor deposition apparatus,
Reaction gas composition (volume%); TiCl ₄ : 2 to 4%, AlCl ₃ : 0.1 to 0.5%, ZrCl ₄ : 0.1 to 0.5%, CH ₄ : 2.5 to ₄ %, CO ₂ : 0.02 to 0.05%, N ₂ : 15 to 20%, H ₂ : remaining,
Reaction atmosphere temperature: 980-1020 ° C.
Reaction atmosphere pressure: 5 to 8 kPa,
In the condition of
Composition formula: (Ti _1-XY Al _X Zr _Y ) C _α N _β O _γ (where X: 0.003 to 0.1, Y: 0.003 to 0.1, and α : 0.3 to 0.6, β: 0.3 to 0.6, γ: 0.05 to 0.3, and a composite of Ti, Al, and Zr satisfying α + β + γ = 1) When the carbonitride oxide layer is formed as an intermediate layer with an average layer thickness of 0.2 to 2 μm,
The Ti, Al, and Zr composite carbonitride oxide layer (hereinafter referred to as “(Ti, Al, Zr) CNO intermediate layer”) has a predetermined high-temperature strength and is in close contact with the lower layer (Ti compound layer). The layer should have excellent properties and bonding strength.

(C) Next, on the (Ti, Al, Zr) CNO intermediate layer, with a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 2.3~4%,} ZrCl 4: 0.02~0.13%, CO 2: 3~8%, HCl: 1.5~3%, H 2 S : 0.05~0.2%, H _2: remainder,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
In the condition of
Composition _{formula: (Al 1-Q Zr Q} ) 2 O 3, ( provided that an atomic ratio, Q: 0.003 to 0.05) and satisfying, and the composite of Al and Zr in an average layer thickness 1~15μm When an oxide (hereinafter referred to as (Al, Zr) ₂ O ₃ ) layer is formed as an upper layer, this (Al, Zr) ₂ O ₃ layer deposited on the (Ti, Al, Zr) CNO intermediate layer is formed. Is a layer having an α-type crystal structure in the state of chemical vapor deposition and having a further improved high-temperature strength as compared with the α-type Al ₂ O ₃ layer. In addition, (Ti, Al, Zr) CNO It must be a layer with excellent adhesion and bonding strength with the intermediate layer.

(D) The (Al, Zr) ₂ O ₃ layer deposited on the (Ti, Al, Zr) CNO intermediate layer is the same corundum hexagonal close-packed crystal as the α-type Al ₂ O ₃ layer. The structure, that is, the atomic arrangement of the unit cell is schematically shown in FIG. 1 ((a) is a perspective view, (b) is a plan view of cross sections 1 to 9), and lattice points are formed from Al, Zr, and oxygen. And composed of crystal grains having a corundum hexagonal close-packed crystal structure in which each of the constituent atoms is present.

(E) α-type Al ₂ O ₃ layer (hereinafter referred to as “conventional α-type Al ₂ O ₃ layer”) constituting the upper layer of the hard coating layer of the conventional coated tool, and the (Ti, Al, Zr) CNO intermediate (Al, Zr) ₂ O ₃ layer (hereinafter referred to as “modified α-type (Al, Zr) ₂ O ₃ layer”) formed by vapor deposition on the layer,
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams in FIGS. 2A and 2B, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, The tilt angle formed by the normal lines of the (0001) plane and the (10-10) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the surface polished surface [the tilt angle of the crystal plane is shown in FIG. (B) shows the case where the inclination angle is 45 degrees, all the inclination angles of the individual crystal grains including these angles are measured. In this case, the crystal grains As described above, the conventional α-type Al ₂ O ₃ layer has Al and oxygen at lattice points, and the modified α-type (Al, Zr) ₂ O ₃ layer has constituent atoms composed of Al, Zr, and oxygen. The corundum type hexagonal close-packed crystal structure that exists, based on the measured tilt angle A distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at an interface between adjacent crystal grains is calculated, and the constituent atomic shared lattice points are calculated. There are N lattice points that do not share constituent atoms in between (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but when the upper limit of N is 28 in terms of distribution frequency, 4 , 8, 14, 24, and 26 (there is no even number)) Create a constituent atomic shared lattice distribution graph that shows the distribution of existing constituent atomic shared lattice points as ΣN + 1 and shows the distribution ratio of each ΣN + 1 to the entire ΣN + 1 In this case (in this case, from the above results, there are no constituent atom shared lattice point forms of Σ5, Σ9, Σ15, Σ25, and Σ27), the conventional α-type Al ₂ O ₃ layer is illustrated in FIG. As you can see, Σ3 In contrast to a relatively low constituent atom shared lattice point distribution graph with a distribution ratio of 30% or less, the modified α-type (Al, Zr) ₂ O ₃ layer has Σ3 as illustrated in FIG. An extremely high constituent atomic shared lattice point distribution graph with a distribution ratio of 50 to 80% is shown.

(F) When forming the modified α-type (Al, Zr) ₂ O ₃ layer, the Zr content in the layer is set to 0.3 to 5 atomic%, and the average layer thickness is set to 1 to 15 μm. , The distribution ratio of Σ3 in the constituent atomic shared lattice distribution graph is as high as 50 to 80%, and as a result, the layer has the desired excellent high-temperature strength, and therefore the Zr content in the layer If either the ratio or the average layer thickness is out of the above range, the distribution ratio of Σ3 in the constituent atom shared lattice point distribution graph becomes less than 50%, and the desired high-temperature strength improvement effect cannot be obtained.
In the modified α-type (Al, Zr) ₂ O ₃ layer and the conventional α-type Al ₂ O ₃ layer, Σ3, Σ7 of the constituent atomic shared lattice point forms at the interface between adjacent crystal grains, When the unit form of Σ11 and Σ11 are illustrated by schematic diagrams, it is as shown in FIGS.

(G) As described above, the modified α-type (Al, Zr) ₂ O ₃ layer is superior in high-temperature hardness and heat resistance provided by the conventional α-type Al ₂ O ₃ layer, and further improved in high-temperature strength. Furthermore, the (Ti, Al, Zr) CNO intermediate layer has excellent adhesion with both the lower layer made of a Ti compound layer and the upper layer made of a modified α-type (Al, Zr) ₂ O ₃ layer. Layer structure of Ti compound layer (lower layer), (Ti, Al, Zr) CNO intermediate layer and modified α-type (Al, Zr) ₂ O ₃ layer (upper layer) As a result, the high-temperature strength of the hard coating layer can be further improved, and as a result, even when it is used for cutting under severe conditions such as high-speed heavy cutting with high heat generation and high load, the intermediate layer the not and conventional target to form a conventional α type the Al ₂ O ₃ layer as an upper layer have Compared to the tool, and exhibits chipping resistance of the hard coating layer is more excellent, also to exhibit wear resistance with excellent long-term.
The research results shown in (a) to (g) 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 one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer having an overall average layer thickness of 3 to 20 μm. A Ti compound layer comprising:
(B) the intermediate layer has an average layer thickness of 0.2-2 μm,
Composition formula: (Ti _1-XY Al _X Zr _Y ) C _α N _β O _γ (where X: 0.003 to 0.1, Y: 0.003 to 0.1, and α : 0.3 to 0.6, β: 0.3 to 0.6, γ: 0.05 to 0.3, and α + β + γ = 1)
A composite oxynitride layer of Ti, Al, and Zr that satisfies the following conditions:
(C) the upper layer has an average layer thickness of 1 to 15 μm, and an α-type crystal structure in the state of chemical vapor deposition;
Composition _{formula: (Al 1-Q Zr Q} ) 2 O 3, ( provided that an atomic ratio, Q: 0.003 to 0.05),
And using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the normal to the surface polished surface is Then, the inclination angle formed by the normal lines of the (0001) plane and (10-10) plane, which are crystal planes of the crystal grains, is measured. In this case, the crystal grains are composed of Al, Zr, and oxygen at lattice points. Each of the constituent atoms has a crystal structure of a corundum hexagonal close-packed crystal structure in which each constituent atom exists, and based on the measured tilt angle obtained as a result, at the interface between adjacent crystal grains. The distribution of lattice points (constituent atom shared lattice points) that share one constituent atom between them is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is a corundum type) 2 or more due to the hexagonal close-packed crystal structure Even if the upper limit of N is 28 from the point of distribution frequency, the even number of 4, 8, 14, 24, and 26 does not exist). In the constituent atom sharing lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1, the constituent atom in which the highest peak exists in Σ3 and the distribution ratio in the entire ΣN + 1 of the Σ3 is 50 to 80% A composite oxide layer of Al and Zr showing a shared lattice distribution graph;
Characterized by a coated tool (surface coated cutting tool) in which the hard coated layer composed of the above (a) to (c) is formed by vapor deposition and the hard coated layer exhibits excellent chipping resistance in high-speed heavy cutting. It is what you have.

Below, the constituent layer of the hard coating layer of the coated tool of this invention is demonstrated in detail.
(A) Lower layer (Ti compound layer)
Ti compound layer composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer exists as a lower layer of the hard coating layer, In addition to contributing to improving the high temperature strength of the hard coating layer due to its excellent high temperature strength, the tool base and the (Ti, Al, Zr) CNO intermediate layer are firmly adhered to each other, so that the tool substrate of the hard coating layer However, if the average layer thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, if the average layer thickness exceeds 20 μm, the high-speed weight accompanied by the generation of high heat is particularly high. The cutting easily causes thermoplastic deformation, which causes uneven wear, so the average layer thickness was determined to be 3 to 20 μm.

(B) Intermediate layer ((Ti, Al, Zr) CNO layer)
The (Ti, Al, Zr) CNO intermediate layer has strong adhesion to both the lower layer (Ti compound layer) and the upper layer (modified α-type (Al, Zr) ₂ O ₃ layer), and the Since the bonding strength is also high, by interposing this (Ti, Al, Zr) CNO intermediate layer, a layer having excellent high-temperature strength as the whole hard coating layer is formed, but the (Ti, Al, Zr) CNO intermediate layer is formed. When the X value indicating the content ratio (atomic ratio) of the Al component as a constituent component in the layer is less than 0.003, or when the Y value indicating the content ratio (atomic ratio) of the Zr component is less than 0.003 Decreases the adhesion and bonding strength with the modified α-type (Al, Zr) ₂ O ₃ layer, which is the upper layer, while the X value exceeds 0.1 or the Y value is 0.1. If it exceeds 1, adhesion with the Ti compound layer as the lower layer, bonding strength Therefore, the X value indicating the content ratio of the Al component in the (Ti, Al, Zr) CNO intermediate layer is set to 0.003 from the viewpoint of ensuring excellent adhesion and bonding strength with both the upper layer and the lower layer. Further, the Y value indicating the content ratio of Zr was set in the range of 0.003 to 0.1.
Similarly, the α value indicating the content ratio (atomic ratio) of C, which is a constituent component in the (Ti, Al, Zr) CNO intermediate layer, the β value indicating the content ratio (atomic ratio) of N, and the O content ratio (atom The γ value indicating the ratio) is predetermined from the viewpoint of adhesion and bonding strength with the Ti compound layer as the lower layer or the modified α-type (Al, Zr) ₂ O ₃ layer as the upper layer. The numerical range was determined. That is, when the α value and β value are less than 0.3, the adhesion and bonding strength with the Ti compound layer as the lower layer are lowered, while when the α value and β value exceed 0.6, Since the content ratio of O is relatively reduced, the adhesion and bonding strength with the modified α-type (Al, Cr) ₂ O ₃ layer, which is the upper layer, are reduced, and the γ value is less than 0.05. In this case, the adhesion with the upper layer and the bonding strength are reduced. On the other hand, when the γ value exceeds 0.3, the adhesion with the lower layer and the bonding strength are reduced. The β value and γ value were set to numerical ranges of 0.3 to 0.6, 0.3 to 0.6, and 0.05 to 0.3, respectively.
Furthermore, if the (Ti, Al, Zr) CNO intermediate layer has a layer thickness of less than 0.2 μm, it cannot be expected to ensure adhesion and bonding strength because the layer thickness is too thin, whereas it exceeds 2 μm. Since the wear resistance of the entire hard coating layer tends to decrease, the layer thickness of the (Ti, Al, Zr) CNO intermediate layer is set in the range of 0.2 to 2 μm.

(C) Upper layer (modified α-type (Al, Zr) ₂ O ₃ layer)
Al, which is a constituent component of the modified α-type (Al, Zr) ₂ O ₃ layer, improves the high-temperature hardness and heat resistance of the layer, and the Zr component has a distribution of Σ3 in the constituent atom sharing lattice distribution graph. The ratio is increased to 50% or more and has an effect of improving the high-temperature strength of the layer. In this case, when the Q value indicating the content ratio of Zr is less than 0.003 in atomic ratio, a desired improvement effect is ensured for the above-described action. On the other hand, if the Q value exceeds 0.05, the distribution ratio of Σ3 in the constituent atomic shared lattice distribution graph becomes less than 50%, and it becomes difficult to ensure the desired high-temperature strength. The Q value was determined to be 0.003 to 0.05.
Further, the distribution ratio of Σ3 in the constituent atomic shared lattice point distribution graph of the modified α-type (Al, Zr) ₂ O ₃ layer is the content ratio of AlCl ₃ , ZrCl ₄ , CO ₂ and HCl constituting the reaction gas. Further, it can be adjusted by the atmospheric reaction pressure, and the higher the distribution ratio of Σ3, the more desirable, but it is difficult to increase the distribution ratio of Σ3 beyond 80% in terms of layer formation. The distribution ratio of Σ3 was set in the range of 50 to 80%.
In any case, the modified α-type (Al, Zr) ₂ O ₃ layer having a Σ3 distribution ratio of 50 to 80% in the constituent atom sharing lattice distribution graph has the conventional α-type Al ₂ O ₃ layer itself. In addition to excellent high-temperature hardness and heat resistance, it has even higher high-temperature strength, so that even under severe cutting conditions such as high-speed heavy cutting, it is possible to sufficiently prevent chipping on the hard coating layer. If the average thickness of the α-type (Al, Zr) ₂ O ₃ layer is less than 1 μm, the hard coating layer cannot be provided with the above-mentioned properties sufficiently, while the average layer thickness exceeds 15 μm. Then, since thermoplastic deformation that causes uneven wear is likely to occur and wear is accelerated, the average layer thickness is determined to be 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 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 tool of this invention has a structure in which the hard coating layer has a (Ti, Al, Zr) CNO intermediate layer interposed between the lower layer and the upper layer (modified α-type (Al, Zr) ₂ O ₃ layer). (Ti, Al, Zr) CNO even when used for cutting various steels and cast irons under high-speed heavy cutting conditions with high heat generation and high load. The presence of the intermediate layer not only ensures the interlayer adhesion and bonding strength of the hard coating layer, but also the modified α-type (Al, Zr) ₂ O ₃ layer has the excellent high-temperature hardness of the conventional Al ₂ O ₃ itself. In addition to heat resistance, it has excellent high-temperature strength, thereby exhibiting excellent chipping resistance and further extending the service life.

  Next, the coated 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 2 to 4 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 processing, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG 160412 were produced.

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 standard / CNMG 160412 chip shapes were formed.

Next, each of the tool bases A to F and the tool bases a to f was charged into a normal chemical vapor deposition apparatus. First, Table 3 (l-TiCN in Table 3 is disclosed in JP-A-6-8010). The combinations shown in Table 5 under the conditions shown in Table 5 are the conditions for forming the TiCN layer having the vertically grown crystal structure described, and the other conditions for forming the normal granular crystal structure. And a Ti compound layer with a target layer thickness deposited as a lower layer of the hard coating layer, and then a (Ti, Al, Zr) CNO intermediate layer [shown as an intermediate layer in Table 4] under the conditions shown in Table 4 (a ) To (e) are vapor-deposited as intermediate layers of the hard coating layer with the combinations and target layer thicknesses also shown in Table 5, and further shown in Table 5 under the conditions shown in Table 4 Modified α type with combination and target layer thickness The coated tools 1 to 13 of the present invention were produced by vapor-depositing (Al), (Zr) ₂ O ₃ layers [shown as modified layers in Table 4] (A) to (E) as upper layers of the hard coating layer, respectively. .

For comparison purposes, as shown in Table 6, the conventional α-type Al ₂ O ₃ layer is formed as the upper layer of the hard coating layer with the target layer thickness shown in Table 6 under the conditions shown in Table 3. Thus, the conventional coated tools 1 to 13 were produced respectively.

Subsequently, the modified α-type (Al, Zr) ₂ O ₃ layer and the conventional α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present invention-coated tools 1 to 13 and the conventional coated tools 1 to 13 described above. Constituent atom shared lattice point distribution graphs were prepared for each of the above using a field emission scanning electron microscope.
That is, the constituent atomic shared lattice point distribution graph shows the field emission scanning in a state where the surface of the modified α-type (Al, Zr) ₂ O ₃ layer and the conventional α-type Al ₂ O ₃ layer is the polished surface. Set in a lens barrel of an electron microscope, and irradiate an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees on the polished surface with an irradiation current of 1 nA to each crystal grain existing in the measurement range of the surface polished surface. Then, using an electron backscatter diffraction image apparatus, a region of 30 × 50 μm at a spacing of 0.1 μm / step is a (0001) plane which is the crystal plane of the crystal grain with respect to the normal line of the polished surface And the tilt angle formed by the normal of the (10-10) plane, and based on the measured tilt angle obtained as a result, each of the constituent atoms is interlinked with the crystal grain at the interface between adjacent crystal grains. Lattice points that share one constituent atom between them (constituent atom sharing The number of lattice points that do not share constituent atoms between the constituent atomic shared lattice points (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal) (If the upper limit of N is 28 from the point of distribution frequency, there is no even number of 4, 8, 14, 24, and 26) When the existing constituent atom shared lattice point form is expressed as ΣN + 1, each ΣN + 1 is It was created by calculating the distribution ratio in the entire ΣN + 1.

In the graph of constituent atomic shared lattice distributions of various modified α-type (Al, Zr) ₂ O ₃ layers and conventional α-type Al ₂ O ₃ layers obtained as a result, the entire ΣN + 1 (from the above results, Σ3, Σ7, The distribution ratios of Σ3 in the total distribution ratios of Σ11, Σ13, Σ17, Σ19, Σ21, Σ23, and Σ29) are shown in Tables 5 and 6, respectively.

In each of the above-mentioned various constituent atomic share lattice point distribution graphs, as shown in Tables 5 and 6, respectively, the modified α-type (Al, Zr) ₂ O ₃ layer of the coated tool of the present invention has a distribution ratio occupied by Σ3. Shows a constituent atomic shared lattice distribution graph in which the ratio is 50 to 80%, whereas the conventional α-type Al ₂ O ₃ layer of the conventional coated tool has a constituent atomic shared lattice with a Σ3 distribution ratio of 30% or less. A point distribution graph was shown.
FIG. 4 is a graph showing the distribution of constituent atomic shared lattice points of the modified α-type (Al, Zr) ₂ O ₃ layer of the coated tool 10 of the present invention, and FIG. 5 shows the conventional α-type Al ₂ O ₃ of the conventional coated tool 4. The constituent atom shared lattice point distribution graphs of the layers are respectively shown.

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

Next, for the various coated tools of the present invention coated tools 1 to 13 and the conventional coated tools 1 to 13, all of them are screwed to the tip of the tool steel tool with a fixing jig,
[Cutting conditions A]
Work material: JIS / S20C round bar,
Cutting speed: 450 m / min,
Incision: 2.7 mm,
Feed: 0.8 mm / rev,
Cutting time: 10 minutes,
Carbon steel dry high-speed high-feed cutting test under normal conditions (normal cutting speed and feed are 250 m / min and 0.3 mm / rev, respectively)
[Cutting conditions B]
Work material: JIS / SCM420 round bar,
Cutting speed: 400 m / min,
Cutting depth: 4.8 mm,
Feed: 0.3 mm / rev,
Cutting time: 5 minutes,
Dry high-speed high-cut cutting test of alloy steel under the following conditions (normal cutting speed and cutting are 250 m / min and 2 mm, respectively)
[Cutting conditions C]
Work material: JIS / FC300 round bar,
Cutting speed: 530 m / min,
Cutting depth: 5.5 mm,
Feed: 0.40 mm / rev,
Cutting time: 5 minutes,
Wet high-speed high-cut cutting test of cast iron under normal conditions (normal cutting speed and cutting are 250 m / min and 2.5 mm, respectively)
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 7.

From the results shown in Tables 5 to 7, in the present coated tools 1 to 13, (Ti, Al, Zr) CNO intermediate layer is formed by vapor deposition as the intermediate layer of the hard coating layer, and through this, the distribution ratio of Σ3 Since the modified α-type (Al, Zr) ₂ O ₃ layer showing the constituent atomic shared lattice distribution graph of 50 to 80% is formed by vapor deposition as an upper layer, high heat generation occurs and the load on the cutting edge Even in high-speed heavy cutting of steel and cast iron with extremely large thickness, the modified α-type (Al, Zr) ₂ O ₃ layer has its own properties along with the high adhesion and bonding strength of the (Ti, Al, Zr) CNO intermediate layer. In addition to the excellent high-temperature hardness and heat resistance that it has, it has excellent high-temperature strength and exhibits excellent chipping resistance. Resistance A conventional α-type Al ₂ O ₃ layer showing a constituent atomic shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less is directly deposited on the lower layer (Ti compound layer) while exhibiting wear properties. In the conventional coated tools 1 to 13 provided with the hard coating layer, since the interlaminar bonding strength and the high temperature strength of the hard coating layer are insufficient in high-speed heavy cutting, chipping occurs in the hard coating layer. It is clear that the service life is reached in a short time.

  As described above, the coated tool of the present invention has an excellent hard coating layer not only for cutting under normal conditions such as various types of steel and cast iron, but also for high-speed heavy cutting that requires particularly high high-temperature strength. Because it shows 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 there.

FIG. 2 is a schematic diagram showing an atomic arrangement of a unit cell of a corundum type hexagonal close-packed crystal constituting an α-type (Al, Zr) ₂ O ₃ layer, where (a) is a perspective view and (b) is a cross section of 1-9. It is a top view. α-type (Al, Zr) is a schematic explanatory view showing the measurement mode of the inclination angle of the crystal grains (0001) plane and (10-10) plane in ₂ O ₃ layer and α-type the Al ₂ O ₃ layer. FIG. 4 is a schematic diagram showing unit forms of constituent atomic shared lattice points at the interface between adjacent crystal grains, where (a) shows Σ3, (b) shows Σ7 (c) and Σ11 unit forms. . It is a constituent atom shared lattice point distribution graph of the modified α-type (Al, Zr) ₂ O ₃ layer of the coated tool 10 of the present invention. 6 is a constituent atomic shared lattice point distribution graph of a conventional α-type Al ₂ O ₃ layer of a conventional coated tool 4.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) The lower layer is one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer having an overall average layer thickness of 3 to 20 μm. A Ti compound layer comprising:
(B) the intermediate layer has an average layer thickness of 0.2-2 μm,
Composition formula: (Ti _1-XY Al _X Zr _Y ) C _α N _β O _γ (where X: 0.003 to 0.1, Y: 0.003 to 0.1, and α : 0.3 to 0.6, β: 0.3 to 0.6, γ: 0.05 to 0.3, and α + β + γ = 1)
A composite oxynitride layer of Ti, Al, and Zr that satisfies the following conditions:
(C) the upper layer has an average layer thickness of 1 to 15 μm, and an α-type crystal structure in the state of chemical vapor deposition;
Composition _{formula: (Al 1-Q Zr Q} ) 2 O 3, ( provided that an atomic ratio, Q: 0.003 to 0.05),
And using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the normal to the surface polished surface is Then, the inclination angle formed by the normal lines of the (0001) plane and (10-10) plane, which are crystal planes of the crystal grains, is measured. In this case, the crystal grains are composed of Al, Zr, and oxygen at lattice points. Each of the constituent atoms has a crystal structure of a corundum hexagonal close-packed crystal structure in which each constituent atom exists, and based on the measured tilt angle obtained as a result, at the interface between adjacent crystal grains. The distribution of lattice points (constituent atom shared lattice points) that share one constituent atom between them is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is a corundum type) 2 or more due to the hexagonal close-packed crystal structure Even if the upper limit of N is 28 from the point of distribution frequency, the even number of 4, 8, 14, 24, and 26 does not exist). In the constituent atom sharing lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1, the constituent atom in which the highest peak exists in Σ3 and the distribution ratio in the entire ΣN + 1 of the Σ3 is 50 to 80% A composite oxide layer of Al and Zr showing a shared lattice distribution graph;
A surface-coated cutting tool in which a hard coating layer composed of the above (a) to (c) is formed by vapor deposition, and the hard coating layer exhibits excellent chipping resistance in high-speed heavy cutting.

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