JP4822119B2 - 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) 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} Cr _Q ) ₂ O ₃ (however, in terms of atomic ratio, Q: 0.01 to 0.1),
A composite oxide of Al and Cr (hereinafter referred to as α-type (Al, Cr) ₂ O ₃ ) layer satisfying the following conditions:
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.

Further, the α type (Al, Cr) ₂ O ₃ layer constituting the hard coating layer of the above coated tool is a corundum type hexagonal close-packed crystal in which constituent atoms consisting of Al, Cr, and oxygen are present at lattice points. The crystal structure, that is, the atomic arrangement of the unit cell of α-type (Al, Cr) ₂ O ₃ is schematically shown in FIG. 1 ((a) is a perspective view and (b) is a plan view of cross sections 1 to 9). It is also known that it is composed of crystal grains having a crystal structure.
JP 52-66508 A 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. When used in high feed, high cutting, high speed heavy cutting conditions, the hard coating layer is not sufficient because the α-type (Al, Cr) ₂ O ₃ layer constituting the hard coating layer does not have sufficient high-temperature strength. The layer is prone to chipping, and as a result, the service life is reached in a relatively short time.

In view of the above, the present inventors pay attention to the coated tool in which the α-type (Al, Cr) ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and particularly the α-type (Al , Cr) As a result of research to improve the high-temperature strength of the ₂ O ₃ layer,
(A) The α-type (Al, Cr) ₂ O ₃ layer as the upper layer constituting the hard coating layer of the conventional coated tool has excellent high-temperature hardness, high-temperature strength, and heat resistance. For example, in a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 2.3~4%,} CrCl 3: 0.04~0.26%, CO 2: 6~8%, HCl: 1.5~3%, H 2 S : 0.05-0.2%, H2: remaining,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
Under the above conditions (referred to as normal conditions), vapor deposition is formed on the Ti compound layer (the lower layer of the conventional coated tool).
But this
Reaction gas composition:% by volume, AlCl ₃ : 6 to 10%, CrCl ₃ : 0.1 to 0.65%, CO ₂ : 10 to 15%, HCl: 3 to 5%, H ₂ S: 0.05 ~ 0.2%, H2: remaining,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 3 to 5 kPa,
In other words, in the reaction gas composition, the content ratio of AlCl ₃ , CrCl ₃ , CO ₂ , and HCl is relatively high and the atmospheric pressure is relatively low (reaction) When vapor deposition is performed on the Ti compound layer (the lower layer of the conventional coated tool) under the high gas component content adjustment low pressure condition), α-type (Al, Cr) ₂ O ₃ formed under the reaction gas component high content adjustment low pressure condition as a result. Layer (hereinafter referred to as “modified α-type (Al, Cr) ₂ O ₃ layer”) is an α-type (Al, Cr) ₂ O ₃ layer (hereinafter referred to as “upper layer”) of the hard coating layer of the conventional coated tool. Compared to “conventional α-type (Al, Cr) ₂ O ₃ layer”), the high-temperature strength is much better.

(B) About the conventional α-type (Al, Cr) ₂ O ₃ layer and the modified α-type (Al, Cr) ₂ O ₃ layer of (a),
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 Has a crystal structure of a corundum type hexagonal close-packed crystal in which constituent atoms composed of Al, Cr, and oxygen are present at lattice points as described above, and are adjacent to each other based on the measured tilt angle. Each of the constituent atoms is one constituent atom between the crystal grains The distribution of shared lattice points (constituent atom shared lattice points) is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points (where N is the crystal structure of the corundum hexagonal close-packed crystal) 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). When the constituent atomic shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 is created (in this case, from the above result, the constituent atomic shared lattice point forms of Σ5, Σ9, Σ15, Σ25, and Σ27) The conventional α-type (Al, Cr) ₂ O ₃ layer shows a constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less as illustrated in FIG. In contrast, the modified α As shown in FIG. 4, the type (Al, Cr) ₂ O ₃ layer shows a constituent atom shared lattice point distribution graph having a high distribution ratio of Σ3 of 60 to 80%, and this high distribution ratio of Σ3. Not only changes depending on the content ratio of AlCl ₃ , CrCl ₃ , CO ₂ and HCl constituting the reaction gas, and the atmospheric reaction pressure, but also includes a Ti compound layer (lower layer) and a modified α-type (Al, It also changes by interposing an intermediate layer (described later) between the Cr) ₂ O ₃ layer.
In the modified α-type (Al, Cr) ₂ O ₃ layer and the conventional α-type (Al, Cr) ₂ O ₃ layer, among the constituent atomic shared lattice point forms at the interface between adjacent crystal grains The unit forms of Σ3, Σ7, and Σ11 are illustrated in schematic diagrams as shown in FIGS.

(C) As described above, the modified α-type (Al, Cr) ₂ O ₃ layer is further improved in addition to the excellent high temperature hardness and heat resistance of the conventional α-type (Al, Cr) ₂ O ₃ layer. Because it has excellent high-temperature strength, even a coated tool in which a modified α-type (Al, Cr) ₂ O ₃ layer is directly deposited on a Ti compound layer can be used under normal conditions such as steel and cast iron. There is no special problem when it is used for cutting. However, when such a coated tool is used for cutting under severe conditions such as high-speed heavy cutting with high heat generation and high load, the upper layer (modified α type ( Since the adhesion of the Al, Cr) ₂ O ₃ layer) is not sufficient, peeling between the lower layer and the upper layer of the hard coating layer is particularly likely to occur.
However, between the lower layer and the upper layer, for example, in a normal chemical vapor deposition apparatus, the reaction gas composition (volume%); TiCl ₄ : 2 to 4%, AlCl ₃ : 0.1 to 0.5%, CrCl _{3 : 0.1~0.5%, CH 4: 2.5~4} %, CO 2: 0.02~0.05%, N 2: 15~20%, H 2: remainder,
Reaction atmosphere temperature: 980-1020 ° C.
Reaction atmosphere pressure: 5 to 8 kPa,
The composition formula: (Ti _1-XY Al _X Cr _Y ) C _α N _β O _γ , (X: 0.003 to 0.1, Y: 0.01 to 0.1 In addition, Ti and Al satisfying α: 0.3 to 0.6, β: 0.3 to 0.6, γ: 0.05 to 0.3, and α + β + γ = 1) And Cr composite oxynitride layer (hereinafter referred to as (Ti, Al, Cr) CNO intermediate layer) as an intermediate layer by chemical vapor deposition,
(Ti, Al, Cr) CNO intermediate layer intervenes to greatly increase the adhesion strength and bonding strength between the lower layer (Ti compound layer) and the upper layer (modified α-type (Al, Cr) ₂ O ₃ layer) And the occurrence of delamination between the lower layer and the upper layer is prevented.

(D) The (Ti, Al, Cr) CNO intermediate layer increases the adhesion strength and bonding strength between the upper layer and the lower layer, and as a result, the occurrence of delamination between the lower layer and the upper layer is prevented, In addition to this, the (Ti, Al, Cr) CNO intermediate layer has an upper layer (modified α-type (Al, Cr) formed by vapor deposition thereon. ) ₂ O ₃ layer) to increase the distribution ratio of Σ3, so that the upper layer (modified α-type (Al, Cr) ₂ O ₃ layer) with a (Ti, Al, Cr) CNO intermediate layer interposed ), The upper limit value of the distribution ratio of Σ3 is increased to 90% (when there is no intermediate layer, the upper limit value of the distribution ratio of Σ3 is 80%). Therefore, a hard coating layer is formed by a laminated structure of a Ti compound layer (lower layer), a (Ti, Al, Cr) CNO intermediate layer (intermediate layer) and a modified α-type (Al, Cr) ₂ O ₃ layer (upper layer). The constructed coated tool is combined with excellent high-temperature strength provided by the Ti compound layer (lower layer), excellent adhesion strength provided by the (Ti, Al, Cr) CNO intermediate layer (intermediate layer), and joint strength. Even when used for cutting under severe conditions such as high-speed heavy cutting with high heat generation and high load, the conventional α-type (Al, Cr) ₂ O ₃ layer is formed as the upper layer without an intermediate layer. Compared to the conventional coated tools, the hard coating layer exhibits excellent chipping resistance and also exhibits excellent wear resistance over a long period of time.
The research results shown in (a) to (d) 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,
_{Formula: (Ti 1-X-Y} Al X Cr Y) C α N β O γ, ( where, X: 0.003 to 0.1, Y: is 0.01 to 0.1, also, alpha : 0.3 to 0.6, β: 0.3 to 0.6, γ: 0.05 to 0.3, and α + β + γ = 1)
A composite oxycarbonitride layer of Ti, Al, and Cr that satisfies
(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} Cr _Q ) ₂ O ₃ (however, in terms of atomic ratio, Q: 0.01 to 0.1),
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 the (10-10) plane, which are crystal planes of the crystal grains, is measured. In this case, the crystal grains are composed of Al, Cr, 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 having the highest peak in Σ3 and the distribution ratio in the entire ΣN + 1 of the Σ3 is 60 to 90% A composite oxide layer of Al and Cr showing a shared lattice point distribution graph,
The hard coating layer formed by vapor deposition of the hard coating layer composed of the above (a) to (c) is characterized by a surface-coated cutting tool that exhibits excellent chipping resistance in high-speed heavy cutting. .

Hereinafter, the reason why the constituent layers of the hard coating layer of the coated tool of the present invention are limited as described above will be described.
(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, it firmly adheres to both the tool substrate and the (Ti, Al, Cr) CNO intermediate layer, and thus 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 fully exerted. On the other hand, if the average layer thickness exceeds 20 μm, particularly high heat generation occurs. In high speed heavy cutting, it becomes easy to cause thermoplastic deformation, which causes uneven wear. Therefore, the average layer thickness is set to 3 to 20 μm.

(B) Intermediate layer ((Ti, Al, Cr) CNO layer)
The (Ti, Al, Cr) CNO intermediate layer has strong adhesion to both the lower layer (Ti compound layer) and the upper layer (modified α-type (Al, Cr) ₂ O ₃ layer). Since the bonding strength is also high, by interposing this (Ti, Al, Cr) CNO intermediate layer, a layer having excellent high-temperature strength as the whole hard coating layer is formed, but (Ti, Al, Cr) CNO By forming the modified α-type (Al, Cr) ₂ O ₃ layer on top of the intermediate layer, the modified α-type (Al, Cr) ₂ O ₃ layer is formed directly on the lower layer without providing the intermediate layer. compared with the case where the vapor deposited, modified α-type (Al, Cr) distribution ratio of Σ3 in ₂ O ₃ layer is further enhanced, the reforming α-type (Al, Cr) ₂ O ₃ layer, a more further excellent It has high temperature strength.
(Ti, Al, Cr) When the X value indicating the content ratio (atomic ratio) of the Al component as a constituent component in the CNO intermediate layer is less than 0.003, or Y indicating the content ratio (atomic ratio) of the Cr component When the value is less than 0.01, the adhesion and bonding strength with the modified α-type (Al, Cr) ₂ O ₃ layer, which is the upper layer, are reduced, while the X value exceeds 0.1. In this case, when the Y value exceeds 0.1, the adhesion and bonding strength with the Ti compound layer, which is the lower layer, are lowered. Therefore, excellent adhesion and bonding strength with both the upper layer and the lower layer are obtained. From the viewpoint of ensuring, the X value indicating the content ratio of the Al component in the (Ti, Al, Cr) CNO intermediate layer is 0.003 to 0.1, and the Y value indicating the Cr content ratio is 0.01 to The range was set to 0.1.
Similarly, an α value indicating the content ratio (atomic ratio) of C, which is a constituent component in the (Ti, Al, Cr) CNO intermediate layer, a β value indicating the content ratio (atomic ratio) of N, and an O content ratio (atom Γ value indicating the ratio) is also determined from the viewpoint of adhesion and bonding strength with the Ti compound layer as the lower layer or the modified α-type (Al, Cr) 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.
In addition, regarding the thickness of the (Ti, Al, Cr) CNO intermediate layer, if the layer thickness is less than 0.2 μm, the layer thickness is too thin and it cannot be expected to ensure adhesion and bonding strength. If the thickness exceeds 2 μm, the wear resistance of the hard coating layer as a whole tends to decrease. Therefore, the thickness of the (Ti, Al, Cr) CNO intermediate layer is set in the range of 0.2 to 2 μm. It was.

(C) Upper layer (modified α-type (Al, Cr) ₂ O ₃ layer)
In the above modified α-type (Al, Cr) ₂ O ₃ layer, Al which is a constituent component thereof improves the high-temperature hardness and heat resistance of the layer, and the Cr component further coexists with the Al component. Although it has the effect | action which improves heat resistance further, if the Q value which shows the content rate of Cr is less than 0.01 by atomic ratio, the desired improvement effect cannot be ensured for the said effect | action, On the other hand, the Q value is 0. When the ratio exceeds 1, the high temperature strength tends to decrease, so the Q value is set to 0.01 to 0.1.
In addition, the distribution ratio of Σ3 in the constituent atomic shared lattice point distribution graph of the modified α-type (Al, Cr) ₂ O ₃ layer is the modified α-type (Al) on the (Ti, Al, Cr) CNO intermediate layer. , Cr) ₂ O ₃ layer is formed by chemical vapor deposition, the content ratio of AlCl ₃ , CrCl ₃ , CO ₂ and HCl constituting the reaction gas, and the atmospheric reaction pressure are adjusted to 60 to 90%. However, in this case, if the distribution ratio of Σ3 is less than 60%, it is not possible to expect an excellent effect of improving high-temperature strength so that chipping does not occur in the hard coating layer in high-speed heavy cutting processing. The higher the ratio, the better. However, since it is difficult to increase the distribution ratio of Σ3 beyond 90% in terms of layer formation, the distribution ratio of Σ3 was determined to be 60 to 90%.
Furthermore, the modified α-type (Al, Cr) ₂ O ₃ layer has a further excellent high-temperature strength in addition to the excellent high-temperature hardness and heat resistance of the conventional α-type (Al, Cr) ₂ O ₃ layer itself. However, if the average layer thickness is less than 1 μm, the above-mentioned properties of the modified α-type (Al, Cr) ₂ O ₃ layer cannot be sufficiently provided in the hard coating layer, When the average layer thickness exceeds 15 μm, thermoplastic deformation that causes uneven wear tends to occur, and wear accelerates. Therefore, the average layer thickness is set to 1 to 15 μm.

  In addition, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone may be vapor-deposited as 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 the present invention has a structure in which a hard coating layer has a (Ti, Al, Cr) CNO intermediate layer interposed between a lower layer and an upper layer (modified α-type (Al, Cr) ₂ O ₃ layer). (Ti, Al, Cr) CNO even when it is used to cut various types of steel and cast iron 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 the modified α-type (Al, Cr) ₂ O ₃ layer is tangled by the conventional (Al, Cr) ₂ O ₃ itself. In addition to the high-temperature hardness and 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 4 under the conditions shown in Table 4 below are the conditions for forming the TiCN layer having the vertically elongated crystal structure described, and other conditions for forming the normal granular crystal structure. And a Ti compound layer with a target layer thickness as a lower layer of the hard coating layer, and then, (Ti, Al, Cr) CNO intermediate layers (a) to (e) under the conditions shown in Table 3 Any one of these is deposited and formed as an intermediate layer of the hard coating layer with the combination and target layer thickness shown in Table 4, and the modified α-type (Al, Cr) ₂ O ₃ layer (under the conditions shown in Table 3) Same as any one of a) to (e) The coated tools 1 to 13 of the present invention were produced by vapor deposition as the upper layer of the hard coating layer with the combinations shown in Table 4 and the target layer thickness.

For comparison purposes, as shown in Table 5, as the upper layer of the hard coating layer, among the conventional α-type (Al, Cr) ₂ O ₃ layers (a) to (e) under the conditions shown in Table 3 Conventionally coated tools 1 to 13 each of which was directly formed on the lower layer (Ti compound layer) were produced.

Subsequently, the modified α type (Al, Cr) ₂ O ₃ layer and the conventional α type (Al, Cr) 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 ₂ O ₃ layers using a field emission scanning electron microscope.
That is, the constituent atom sharing lattice point distribution graph is a state where the surface of the modified α-type (Al, Cr) ₂ O ₃ layer and the conventional α-type (Al, Cr) ₂ O ₃ layer is a polished surface. A crystal which is set in a lens barrel of a field emission scanning electron microscope and exists in the measurement range of the surface polished surface with an electron beam having an acceleration voltage of 15 kV at an incident angle of 70 degrees and an irradiation current of 1 nA on the polished surface. Irradiate each grain, and use an electron backscatter diffraction imaging apparatus, and a region of 30 × 50 μm at a spacing of 0.1 μm / step is the crystal plane of the crystal grain with respect to the normal of the surface polished surface The inclination angles formed by the normals of the (0001) plane and the (10-10) plane are measured, and based on the measurement inclination angles obtained as a result, each of the constituent atoms is formed at the interface between adjacent crystal grains. Lattice points (structures that share one constituent atom between the crystal grains) The distribution of atomic shared lattice points is calculated, and N 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 in the crystal structure of the corundum hexagonal close-packed crystal) However, when 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 atomic shared lattice point form is expressed by ΣN + 1, It was created by determining the distribution ratio of ΣN + 1 in the entire ΣN + 1.

In the graph of constituent atomic shared lattice points of the various modified α-type (Al, Cr) ₂ O ₃ layers and conventional α-type (Al, Cr) ₂ O ₃ layers obtained as a result, the entire ΣN + 1 (from the above results) The distribution ratios of Σ3 in the total distribution ratios of Σ3, Σ7, Σ11, Σ13, Σ17, Σ19, Σ21, Σ23, and Σ29) are shown in Tables 4 and 5, respectively.

In each of the above-mentioned various constituent atomic share lattice point distribution graphs, as shown in Tables 4 and 5, each of the modified α-type (Al, Cr) ₂ O ₃ layer of the coated tool of the present invention has a distribution ratio occupied by Σ3. Shows a distribution graph of constituent atomic shared lattice points with 60 to 90%, whereas the conventional α-type (Al, Cr) ₂ O ₃ layer of the conventional coated tool has a Σ3 distribution ratio of 30% or less. The constituent atomic shared lattice point distribution graph was shown.
4 is a graph showing the distribution of constituent atomic shared lattice points of the modified α-type (Al, Cr) ₂ O ₃ layer of the coated tool 7 of the present invention, and FIG. 5 is a graph showing the conventional α-type (Al, Cr) of the conventional coated tool 7. ) Each of the constituent atomic shared lattice point distribution graphs of the ₂ O ₃ layer is 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 / S25C round bar,
Cutting speed: 440 m / min,
Cutting depth: 2.5 mm,
Feed: 0.7 mm / rev,
Cutting time: 8 minutes,
Dry continuous high-speed high-feed cutting test of carbon steel under the conditions (normal cutting speed and feed are 250 m / min and 0.3 mm / rev, respectively)
[Cutting conditions B]
Work material: JIS / SCr420H round bar,
Cutting speed: 420 m / min,
Cutting depth: 5.0 mm,
Feed: 0.35 mm / rev,
Cutting time: 5 minutes,
Dry continuous high-speed high-cut cutting test of alloy steel under the conditions (normal cutting speed and cutting are 250 m / min and 2 mm, respectively)
[Cutting conditions C]
Work material: JIS / FC250 round bar,
Cutting speed: 550 m / min,
Cutting depth: 6.0 mm,
Feed: 0.4 mm / rev,
Cutting time: 5 minutes,
Wet continuous high-speed high-cut cutting test of cast iron under the conditions of (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 6.

From the results shown in Tables 4 to 6, in the present coated tools 1 to 13, (Ti, Al, Cr) 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, Cr) ₂ O ₃ layer showing a constituent atomic shared lattice distribution graph of 60 to 90% is formed as an upper layer by vapor deposition, high heat generation occurs and the load on the cutting blade Even in high-speed heavy cutting of steel and cast iron with a very large thickness, the modified α-type (Al, Cr) ₂ O ₃ layer has its own properties along with the high adhesion and bonding strength of the (Ti, Al, Cr) 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 The conventional α-type (Al, Cr) ₂ O ₃ layer showing a constituent atomic shared lattice distribution graph in which the distribution ratio of Σ3 is 30% or less directly on the lower layer (Ti compound layer), while exhibiting wear. In the conventional coated tools 1 to 13 each having a hard coating layer formed by vapor deposition, chipping occurs in the hard coating layer because the interlaminar bonding strength and high temperature strength of the hard coating layer are insufficient in high-speed heavy cutting. It is clear that the service life is reached in a relatively 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.

It is a schematic diagram showing the atomic arrangement of the unit cell of the corundum type hexagonal close-packed crystal constituting the α-type (Al, Cr) ₂ O ₃ layer, (a) is a perspective view, (b) is a cross section of 1-9 It is a top view. α-type (Al, Cr) is a schematic explanatory view showing the measurement mode of the crystal grains (0001) plane and (10-10) plane inclination angle of the 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 atomic shared lattice point distribution graph of the modified α-type (Al, Cr) ₂ O ₃ layer of the coated tool 7 of the present invention. 4 is a constituent atomic shared lattice point distribution graph of a conventional α-type (Al, Cr) ₂ O ₃ layer of a conventional coated tool 7.

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,
_{Formula: (Ti 1-X-Y} Al X Cr Y) C α N β O γ, ( where, X: 0.003 to 0.1, Y: is 0.01 to 0.1, also, alpha : 0.3 to 0.6, β: 0.3 to 0.6, γ: 0.05 to 0.3, and α + β + γ = 1)
A composite oxycarbonitride layer of Ti, Al, and Cr that satisfies
(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} Cr _Q ) ₂ O ₃ (however, in terms of atomic ratio, Q: 0.01 to 0.1),
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 the (10-10) plane, which are crystal planes of the crystal grains, is measured. In this case, the crystal grains are composed of Al, Cr, 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 having the highest peak in Σ3 and the distribution ratio in the entire ΣN + 1 of the Σ3 is 60 to 90% A composite oxide layer of Al and Cr showing a shared lattice point 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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