JP2008044050A - Surface-coated cutting tool having hard coating layer exhibiting excellent chipping resistance in high-speed heavy duty cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool having a hard coating layer exhibiting excellent chipping resistance in high-speed heavy duty cutting. <P>SOLUTION: The surface of a tool substrate composed of WC base carbide alloy or TiCN base cermet is provided with Ti compound layer as a lower layer (a), a compound carbonitride oxide layer of Ti, Al, Cr, and Zr satisfying a specified composition formula as an intermediate layer (b), and a composite oxide layer of Al, Cr, and Zr as an upper layer (c), which has α-type crystal structure in a chemical vapor deposition state, and satisfies a specificed composition formula. The upper layer composed of the compound oxide layer of Al, Cr, and Zr shows a specific constituent atom sharing lattice point distribution graph obtained by irradiating individual crystal particles having a hexagonal crystal lattice existing in a measuring range of a surface-polished plane with electron beams, measuring a tilt angle formed by the normal lines of face (0001) and face (10-10) as a crystal plane of the crystal particles with respect to the normal line of the surface-polished plane. <P>COPYRIGHT: (C)2008,JPO&INPIT

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, to α-type the Al ₂ O ₃ layer constituting the hard coating layer high-temperature strength is not sufficient, the hard coating layer chipping As a result, the service life is reached in a relatively short time.

The present inventors have, from the viewpoint as described above, focuses on coated tool α type the Al ₂ O ₃ layer described above constituting the upper layer of the hard coating layer, in particular of the α-type the Al ₂ O ₃ layer As a result of research to improve high temperature strength,
(A) The α-type Al ₂ O ₃ layer as an upper layer constituting a hard coating layer of a conventional coated tool has excellent high-temperature hardness and heat resistance, and this layer is, for example, a normal chemical vapor deposition apparatus. At
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%, CrCl ₃ : 0.05 to 0.5%, ZrCl ₄ : 0.05 to 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,
In condition, composition _{formula: (Ti 1-X-Y} -Z Al X Cr Y Zr Z) C α N β O γ, ( where, X: 0.003~0.1, Y: 0.003~0 .1, Z: 0.003-0.1, α: 0.3-0.6, β: 0.3-0.6, γ: 0.05-0.3, and When a composite carbonitride oxide layer of Ti, Al, Cr, and Zr that satisfies α + β + γ = 1) is formed by chemical vapor deposition as an intermediate layer,
The composite oxycarbonitride layer of Ti, Al, Cr, and Zr (hereinafter referred to as “(Ti, Al, Cr, Zr) CNO intermediate layer”) has a predetermined high-temperature strength and a lower layer (Ti compound layer). ) And excellent adhesion and bonding strength.

(C) Next, on the (Ti, Al, Cr, Zr) CNO intermediate layer, with a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 2.3~4%,} CrCl 3: 0.02~0.21%, 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: 1000 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
In the condition of
Composition formula: (Al _{1 -Q—R} Cr _Q Zr _R ) ₂ O ₃ (wherein, in terms of atomic ratio, Q: 0.005 to 0.07, R: 0.003 to 0.05), When an Al, Cr, and Zr composite oxide (hereinafter, referred to as (Al, Cr, Zr) ₂ O ₃ ) layer having an average layer thickness of 1 to 15 μm is deposited as an upper layer, this (Al _{1-Q— The R} Cr _Q Zr _R ) ₂ O ₃ layer has an α-type crystal structure in the state of chemical vapor deposition, and is compared with the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the conventional coated tool. In addition, the high-temperature strength is a layer that is remarkably improved, and in addition, the layer is also excellent in adhesion and bonding strength with the (Ti, Al, Cr, Zr) CNO intermediate layer.

(D) The (Al, Cr, Zr) ₂ O ₃ layer deposited on the (Ti, Al, Cr, Zr) CNO intermediate layer is the same corundum hexagonal outermost layer as the α-type Al ₂ O ₃ layer. The crystal structure of the dense crystal, 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 a cross section 1 to 9). , Zr, and oxygen, which are composed of crystal grains having a crystal structure of a corundum type hexagonal close-packed crystal each having a constituent atom.

(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 above (Ti, Al, Cr, Zr) (Al, Cr, Zr) ₂ O ₃ layer (hereinafter referred to as “modified α-type (Al, Cr, Zr) ₂ O ₃ layer”) formed by vapor deposition on the CNO intermediate 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 polished surface [FIG. 2 (a) shows the tilt angle of the crystal plane. (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 includes Al and oxygen at lattice points, and the modified α-type (Al, Cr, Zr) ₂ O ₃ layer includes Al, Cr, Zr, and oxygen. It has a corundum type hexagonal close-packed crystal structure in which each constituent atom exists, and the resulting measured gradient Based on the above, the 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 the interface between adjacent crystal grains is calculated, There are N lattice points that do not share constituent atoms between 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, but the upper limit of N is 28 in terms of distribution frequency) In this case, there is no even number of 4, 8, 14, 24, and 26). The existing constituent atomic shared lattice point form is represented by ΣN + 1, and the constituent atomic shared lattice points indicating the distribution ratio of each ΣN + 1 in the entire ΣN + 1 When a distribution graph is created (in this case, from the above result, 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 Whereas exhibit relatively low atom sharing lattice point distribution graph distribution ratio of 30% or less of [sum] 3, the reforming α-type _{(Al, Cr, Zr) 2} O 3 layer, in FIG. 4 As illustrated, a very high constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 50 to 80% is shown.

(F) When forming the modified α-type (Al, Cr, Zr) ₂ O ₃ layer, the Cr content in the layer is 0.5-7 atomic%, and the Zr content is 0.3-5 atomic%. In addition, by setting the average layer thickness to 1 to 15 μm, the distribution ratio of Σ3 in the constituent atomic shared lattice distribution graph becomes as high as 50 to 80%. As a result, the layer has the desired excellent high-temperature strength. Therefore, if any of the Cr content ratio, the Zr content ratio, and the average layer thickness in the layer is out of the above range, the distribution ratio of Σ3 in the constituent atom sharing lattice distribution graph is 50%. The desired high-temperature strength improvement effect cannot be obtained.
In the modified α-type (Al, Cr, Zr) ₂ O ₃ layer and the conventional α-type Al ₂ O ₃ layer, Σ3 among the constituent atomic shared lattice point forms at the interface between adjacent crystal grains, When unit forms of Σ7 and Σ11 are illustrated by schematic diagrams, they are as shown in FIGS.

(G) As described above, the modified α-type (Al, Cr, Zr) ₂ O ₃ layer was further improved in addition to the excellent high-temperature hardness and heat resistance of the conventional α-type Al ₂ O ₃ layer. Further, the (Ti, Al, Cr, Zr) CNO intermediate layer has a high temperature strength. The lower layer is made of a Ti compound layer and the upper layer is made of a modified α-type (Al, Cr, Zr) ₂ O ₃ layer. The Ti compound layer (lower layer), the (Ti, Al, Cr, Zr) CNO intermediate layer, and the modified α-type (Al, Cr, Zr) ₂ have excellent adhesion and bonding strength. The hard coating layer consisting of a layer structure called the O ₃ layer (upper layer) is further improved in its high-temperature strength as a whole, and as a result, cutting under severe conditions such as high-speed heavy cutting with high heat generation and high load. when used in the processing may not have the intermediate layer and conventional α-type Al ₂ O ₃ The compared with the conventional coated tool was formed as an upper layer, 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,
_{Formula: (Ti 1-X-Y} -Z Al X Cr Y Zr Z) C α N β O γ, ( where, X: 0.003~0.1, Y: 0.003~0.1 , Z : 0.003 to 0.1, 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, Cr and Zr 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-R} Cr Q Zr R) 2 O 3, ( provided that an atomic ratio, Q: 0.005~0.07, R: 0.003~0.05 ),
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 have Al, Cr, Zr, and oxygen at lattice points. Each of the constituent atoms has a crystal structure of a corundum type hexagonal close-packed crystal in which each of the constituent atoms is composed of The distribution of lattice points that share one constituent atom between crystal grains (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 Crystal structure of corundum hexagonal close-packed crystals 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 this case, in the constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1, the highest peak exists in Σ3, and the distribution ratio of the Σ3 in the entire ΣN + 1 is 50 to 80%. A composite oxide layer of Al, Cr, and Zr showing a constituent atomic 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, it firmly adheres to both the tool base and the (Ti, Al, Cr, Zr) CNO intermediate layer, and thus the hard coating layer Although it has the effect of improving the adhesion to the tool substrate, 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. Thus, high-speed heavy cutting is likely to cause thermoplastic deformation, which causes uneven wear, so the average layer thickness was determined to be 3 to 20 μm.

(B) Intermediate layer ((Ti, Al, Cr, Zr) CNO layer)
The (Ti, Al, Cr, Zr) CNO intermediate layer has strong adhesion to both the lower layer (Ti compound layer) and the upper layer (modified α-type (Al, Cr, Zr) ₂ O ₃ layer). In addition, since the bonding strength is also high, by interposing this (Ti, Al, Cr, Zr) CNO intermediate layer, a layer having excellent high-temperature strength as a whole hard coating layer is formed. , Al, Cr, Zr) X value indicating the content ratio (atomic ratio) of the Al component which is a constituent component in the CNO intermediate layer, Y value indicating the content ratio (atomic ratio) of the Cr component, and the content ratio (atom) of the Zr component When the Z value indicating the ratio is less than 0.003, the adhesion and bonding strength with the modified α-type (Al, Cr, Zr) ₂ O ₃ layer, which is the upper layer, are reduced. When the value, Y value, and Z value each exceed 0.1, the lower layer Ti Since the adhesion and bonding strength with the compound layer are lowered, from the viewpoint of ensuring excellent adhesion and bonding strength with both the upper layer and the lower layer, in the (Ti, Al, Cr, Zr) CNO intermediate layer The X value indicating the content ratio of the Al component, the Y value indicating the content ratio of Cr, and the Z value indicating the content ratio of Zr were set in the range of 0.003 to 0.1.
In addition, α value indicating the content ratio (atomic ratio) of C, which is a constituent component in the (Ti, Al, Cr, Zr) CNO intermediate layer, β value indicating the content ratio (atomic ratio) of N, and O content ratio Regarding the γ value indicating (atomic ratio), from the viewpoint of adhesion and bonding strength with the Ti compound layer as the lower layer or the modified α-type (Al, Cr, Zr) ₂ O ₃ layer as the upper layer. , Each was set to a predetermined numerical range. 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 layer thickness of the (Ti, Al, Cr, Zr) CNO intermediate layer is less than 0.2 μm, the layer thickness is too thin, so that it is not possible to expect adhesion and bonding strength, while 2 μm If it exceeds, the wear resistance of the hard coating layer as a whole tends to decrease, so the thickness of the (Ti, Al, Cr, Zr) CNO intermediate layer is set in the range of 0.2 to 2 μm. .

(C) Upper layer (modified α-type (Al, Cr, Zr) ₂ O ₃ layer)
In the modified α-type (Al, Cr, Zr) ₂ O ₃ layer, the constituent Al component improves the high-temperature hardness and heat resistance of the layer, and the Cr component further increases the heat resistance in coexistence with the Al component. In addition, both the Cr component and the Zr component have the effect of increasing the distribution ratio of Σ3 in the constituent atom shared lattice distribution graph, and the modified α-type (Al, Cr, Zr) ₂ O ₃ layer Co-existence of Cr component and Zr component increases the distribution ratio of Σ3 in the modified α-type (Al, Cr, Zr) ₂ O ₃ layer to 50 to 80%, and thereby the modified α The high temperature strength of the mold (Al, Cr, Zr) ₂ O ₃ layer is greatly improved. In this case, the Q value indicating the Cr content ratio is less than 0.005 by atomic ratio, and the Zr content ratio is also indicated. If the R value is less than 0.003 in atomic ratio, a desired improvement effect can be obtained for the above action. On the other hand, when the Q value exceeds 0.07 and the R value exceeds 0.05, the distribution ratio of Σ3 in the constituent atom shared lattice point distribution graph is less than 50%. As a result, it becomes difficult to ensure the desired high-temperature strength. Therefore, the Q value was set to 0.005 to 0.07, and the R value was set to 0.003 to 0.05.
Further, the distribution ratio of Σ3 in the constituent atomic shared lattice point distribution graph of the above modified α-type (Al, Cr, Zr) ₂ O ₃ layer is AlCl ₃ , CrCl ₃ , ZrCl ₄ , CO ₂ constituting the reaction gas. It can be adjusted by the content ratio of HCl and HCl, and also by the atmospheric reaction pressure, and the higher the distribution ratio of Σ3, the better, but it is difficult to increase the distribution ratio of Σ3 beyond 80% in terms of layer formation Therefore, the distribution ratio of Σ3 is set in the range of 50 to 80%.
In any case, the modified α-type (Al, Cr, Zr) ₂ O ₃ layer in which the distribution ratio of Σ3 in the constituent atom sharing lattice distribution graph is 50 to 80% is 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 even under severe cutting conditions such as high-speed heavy cutting, it can sufficiently prevent chipping on the hard coating layer, If the average thickness of the modified α-type (Al, Cr, Zr) ₂ O ₃ layer is less than 1 μm, the hard coating layer cannot be provided with the above-mentioned properties sufficiently, but the average layer thickness thereof When the 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.

In the coated tool of the present invention, the hard coating layer has a (Ti, Al, Cr, Zr) CNO intermediate layer interposed between the lower layer and the upper layer (modified α-type (Al, Cr, Zr) ₂ O ₃ layer). Even when it is used for cutting various steels and cast irons under high-speed heavy cutting conditions with high heat generation and high load, (Ti, Al , Cr, Zr) CNO intermediate layer ensures the interlayer adhesion and bonding strength of the hard coating layer, and the modified α-type (Al, Cr, Zr) ₂ O ₃ layer is a conventional Al ₂ O ₃ layer itself. In addition to the excellent 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 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 formed as a lower layer of the hard coating layer, and then (Ti, Al, Cr, Zr) CNO intermediate layer under the conditions shown in Table 4 Any one of (a) to (e) is formed by vapor deposition as an intermediate layer of the hard coating layer with the combination and target layer thickness also shown in Table 5, and under the conditions shown in Table 4, Combinations and goals shown in 5 Reforming α type with a thickness (Al, Cr, _Zr) present invention by 2 _{O 3} layer [Table 4 in this invention the top layer] of the (a) ~ (e) depositing formed as an upper layer of the hard coating layer Coated tools 1 to 13 were produced, 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, Cr, Zr) ₂ O ₃ layer and the conventional α-type Al ₂ O 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 _three layers using a field emission scanning electron microscope.
That is, the constituent atomic share lattice point distribution graph shows field emission in a state where the surfaces of the modified α-type (Al, Cr, Zr) ₂ O ₃ layer and the conventional α-type Al ₂ O ₃ layer are polished surfaces. Set in a lens barrel of a scanning electron microscope, and each crystal grain existing in the measurement range of the surface polished surface is irradiated with an electron beam having an acceleration voltage of 15 kV at an incident angle of 70 degrees on the polished surface with an irradiation current of 1 nA. The surface of the crystal grain is the crystal plane of the surface polished surface with respect to the normal of the surface polished surface at an interval of 0.1 μm / step using an electron backscatter diffraction image apparatus (0001) ) Plane and (10-10) plane normal angle are measured, and based on the measured tilt angle obtained as a result, each of the constituent atoms is crystallized at the interface between adjacent crystal grains. Lattice points that share one constituent atom between grains (constituent element The distribution of (shared lattice points) is calculated, and there are 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). When 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 existing constituent atom shared lattice point form is expressed as ΣN + 1, each ΣN + 1 Was calculated by calculating the distribution ratio of ΣN + 1.

In the graph of constituent atomic shared lattice distributions of various modified α-type (Al, Cr, 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, The distribution ratios of Σ3 in the total distribution ratios of Σ7, 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, Cr, Zr) ₂ O ₃ layer of the coated tool of the present invention occupies Σ3. In contrast to the constituent atomic shared lattice point distribution graph with a distribution ratio of 50 to 80%, the conventional α-type Al ₂ O ₃ layer of the conventional coated tool has a constituent ratio with a Σ3 distribution ratio of 30% or less. The shared grid 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, Zr) ₂ O ₃ layer of the coated tool 8 of the present invention, and FIG. 5 is the conventional α-type Al ₂ of the conventional coated tool 6. The constituent atomic shared lattice point distribution graphs of the O ₃ layer 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, with respect to 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 with a fixing jig to the tip of the tool steel tool,
[Cutting conditions A]
Work material: JIS / S30C round bar,
Cutting speed: 430 m / min,
Cutting depth: 2.6 mm,
Feed: 0.6 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 / SNCM415 round bar,
Cutting speed: 320 m / min,
Cutting depth: 4.5 mm,
Feed: 0.30 mm / rev,
Cutting time: 5 minutes,
Dry 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 / FC200 round bar,
Cutting speed: 560 m / min,
Cutting depth: 5.7 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 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, according to the present invention coated tools 1 to 13, (Ti, Al, Cr, Zr) CNO intermediate layer is formed by vapor deposition as the intermediate layer of the hard coating layer, and through this, Σ3 Since the modified α-type (Al, Cr, Zr) ₂ O ₃ layer showing a constituent atomic shared lattice point distribution graph with a distribution ratio of 50 to 80% is formed by vapor deposition as an upper layer, it involves high heat generation, and Even in high-speed heavy cutting of steel or cast iron, which has an extremely heavy load on the cutting edge, the modified α-type (Al, Cr, Zr) has high adhesion and bonding strength of the (Ti, Al, Cr, Zr) CNO intermediate layer. ) In addition to the excellent high-temperature hardness and heat resistance of the ₂ O ₃ layer, it has excellent high-temperature strength, so it exhibits excellent chipping resistance. Is significantly suppressed, A conventional α-type Al 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 excellent wear resistance over a long period of time In the conventional coated tools 1 to 13 having the hard coating layer formed by vapor deposition, since the interlaminar bonding strength and the high temperature strength of the hard coating layer are insufficient in high speed heavy cutting, the hard coating layer is not chipped. It is clear that it occurs and reaches the service life 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.

The schematic diagram showing the atomic arrangement of the unit cell of the corundum type hexagonal close-packed crystal constituting the α-type (Al, Cr, Zr) ₂ O ₃ layer, (a) is a perspective view, (b) is a cross-section 1 FIG. α-type (Al, Cr, Zr) 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 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, Cr, Zr) ₂ O ₃ layer of the present coated tool 8. 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 6.

Claims (1)

On the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base 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} -Z Al X Cr Y Zr Z) C α N β O γ, ( where, X: 0.003~0.1, Y: 0.003~0.1 , Z : 0.003 to 0.1, 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, Cr and Zr 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-R} Cr Q Zr R) 2 O 3, ( provided that an atomic ratio, Q: 0.005~0.07, R: 0.003~0.05 ),
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 have Al, Cr, Zr, and oxygen at lattice points. Each of the constituent atoms has a crystal structure of a corundum type hexagonal close-packed crystal in which each of the constituent atoms is composed of The distribution of lattice points that share one constituent atom between crystal grains (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 Crystal structure of corundum hexagonal close-packed crystals 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 this case, in the constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1, the highest peak exists in Σ3, and the distribution ratio of the Σ3 in the entire ΣN + 1 is 50 to 80%. A composite oxide layer of Al, Cr, and Zr showing a constituent atomic 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.

Images