JP6791809B2 - Surface coating cutting tool - Google Patents

Description

The present invention relates to a surface coated cutting tool comprising a substrate and a coating formed on the substrate.

In recent years, there has been a demand for cutting tools that exhibit excellent tool life under various cutting conditions. As the required performance of the tool material, it is more important to improve the wear resistance and the fracture resistance, which are directly related to the tool life. Therefore, in order to improve these characteristics, a coating cutting tool in which a plurality of coatings made of materials having different lattice constants are laminated on the surface of a base material is used.

According to Japanese Patent Application Laid-Open No. 08-134629 (Patent Document 1), excellent wear resistance is obtained by forming the surface of a composite high-hardness material for tools into a laminated structure including two or more compound layers composed of fine particles. A composite high hardness material for tools showing the above is disclosed.

In Japanese Patent Application Laid-Open No. 2010-207917 (Patent Document 2), a hard coating layer of a surface coating cutting tool is alternately laminated with a thin layer B and a thin layer C via the thin layer A, and the thin layer A is formed by (Patent Document 2). Either the Ti, Al) N layer or the (Ti, Al, Si) N layer, the thin layer B, the (Cr, Al) N layer or the (Cr, Al, Si) N layer, or the thin layer. A surface coating cutting tool exhibiting excellent chipping resistance by forming C as a (Ti, Si) N layer is disclosed.

In Japanese Patent Application Laid-Open No. 2008-186371 (Patent Document 3), a coating film of a surface coating cutting tool is laminated with layers A and B via a layer C, and the layer A is subjected to the chemical formula Al _a Ti _b M. The first composite represented by _c (0.4 <a <0.75, 0 ≦ b <0.6, 0 <c <0.3, a + b + c = 1, M represents at least one specific element). The metal nitride, carbonitride, nitrogen oxide or carbonitride oxide is used, and the B layer is a second composite metal represented by the chemical formula Ti _{d S e} (0 <e <0.3, d + e = 1). A surface coating cutting tool capable of achieving a long life by using carbonitride and using TiN as the C layer is disclosed.

Japanese Unexamined Patent Publication No. 08-134629 JP-A-2010-207917 Japanese Unexamined Patent Publication No. 2008-183761

However, in the techniques of Patent Documents 1 to 3, the difference in lattice constant of each layer is small, and the fracture resistance is insufficient in high-speed, high-efficiency machining with a high heat load.

Therefore, an object of the present invention is to provide a surface-coated cutting tool that exhibits excellent fracture resistance in high-speed, high-efficiency machining with a high heat load.

The surface coating cutting tool according to one aspect of the present invention is
A surface-coated cutting tool comprising a base material and a coating formed on the base material.
The coating includes a laminated structure in which A layer, B layer, C layer and D layer are repeatedly laminated in this order.
Each of the A layer, the B layer, the C layer and the D layer is a group 4 element (Ti, Zr, Hf, etc.), a group 5 element (V, Nb, Ta, etc.) and a group 6 element in the periodic table. It is a nitride of at least two or more elements selected from the group consisting of (Cr, Mo, W, etc.), Al, Si, B and Y.
Lattice constant _{L A} of the A layer, the lattice constant _{L B} of the B layer, the lattice constant _{L D} lattice constant _{L C} and the D layer of the layer C, the following formula (I) and related formula (II) The filling,
_{L A} <L B <L _C Formula (I)
_{L A} <L D <L _C formula (II)
In the laminated structure, the difference in lattice constant between adjacent layers is 0.0500 Å or more and 0.1000 Å or less.
The lattice constant _{L A,} the lattice constant _{L B,} the maximum value of the difference between the two lattice constants chosen from among the lattice constant _{L C,} and the lattice constant _{L D} is less 0.1500Å least 0.1100A,
Each of the A layer, the B layer, the C layer and the D layer has a cubic crystal structure.
It is a surface coating cutting tool.

According to the above, it is possible to provide a surface coating cutting tool exhibiting excellent fracture resistance in high-speed, high-efficiency machining with a high heat load.

It is a figure explaining the structural example of the surface coating cutting tool which concerns on Embodiment 1 of this invention. It is another figure explaining the structural example of the surface covering cutting tool which concerns on Embodiment 1 of this invention. It is a figure explaining the structural example of the surface coating cutting tool which concerns on Embodiment 2 of this invention.

[Explanation of Embodiments of the Present Invention]
First, embodiments of the present invention will be listed and described.

The surface coating cutting tool according to one aspect of the present invention is
(1) A surface-coated cutting tool including a base material and a coating film formed on the base material.
The coating includes a laminated structure in which A layer, B layer, C layer and D layer are repeatedly laminated in this order.
Each of the A layer, the B layer, the C layer and the D layer is selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Al, Si, B and Y in the periodic table. It is a nitride of more than a species of element,
Lattice constant _{L A} of the A layer, the lattice constant _{L B} of the B layer, the lattice constant _{L D} lattice constant _{L C} and the D layer of the layer C, the following formula (I) and related formula (II) The filling,
_{L A} <L B <L _C Formula (I)
_{L A} <L D <L _C formula (II)
In the laminated structure, the difference in lattice constant between adjacent layers is 0.0500 Å or more and 0.1000 Å or less.
The lattice constant _{L A,} the lattice constant _{L B,} the maximum value of the difference between the two lattice constants chosen from among the lattice constant _{L C,} and the lattice constant _{L D} is 0.1500Å more 0.1100A,
Each of the A layer, the B layer, the C layer and the D layer has a cubic crystal structure.
It is a surface coating cutting tool.

The surface-coated cutting tool is excellent in high-speed, high-efficiency machining with a high heat load because the difference in lattice constant between adjacent layers is 0.0500 Å or more and 0.1000 Å or less in the laminated structure contained in the coating. It is possible to show fracture resistance. The reason for this is not clear, but if the lattice constant difference between adjacent layers is 0.0500 Å or more, both strains at the time of lattice matching are sufficient, so that the fracture resistance is improved and the lattice constant difference is 0.1000 Å. It is presumed that the following is because the crystal lattice shows continuity at the interface and the adhesion between adjacent layers is improved.

Surface-coated cutting tool, wherein the lattice constant _{L A,} the lattice constant _{L B,} the maximum value of the difference between the two lattice constants chosen from among the lattice constant _{L C,} and the lattice constant _{L D} is more than 0.1100Å 0. When it is 1500 Å or less, it is possible to exhibit excellent fracture resistance in high-speed, high-efficiency machining with a high heat load. This is because when the maximum value of the lattice constant difference is 0.1100 Å or more, the lattice strain inside the laminated structure is sufficient and the fracture resistance is improved, and when the lattice constant difference is 0.1500 Å or less, each layer. It is presumed that this is because the cubic crystal structure at the interface of the above surface has good crystallinity and therefore the fracture resistance is improved.

(2) In the laminated structure, it is preferable that the layers containing Si are not adjacent to each other. According to this, the surface coating cutting tool can exhibit excellent fracture resistance. Since the crystallinity of the layer containing Si tends to decrease and the structure tends to be miniaturized, if the layers containing Si are adjacent to each other, the continuity of the lattice cannot be maintained and the fracture resistance may decrease. ..

(3) It is preferable that the A layer, the B layer, the C layer and the D layer each have a layer thickness of 1 nm or more and 110 nm or less. If the layer thickness is less than 1 nm, the laminated structure is almost eliminated due to the diffusion of elements between the layers, a mixed layer is formed, and the fracture resistance may be lowered. On the other hand, if the layer thickness exceeds 110 nm, a region having a small lattice strain is formed in the laminated structure, and the fracture resistance may be lowered.

(4) The B layer and the D layer preferably have the same composition. According to this, the fracture resistance is improved. The reason for this is not clear, but it is presumed that the overall strain balance of the laminated structure is improved.

(5) The laminated structure preferably has a total thickness of 0.5 μm or more and 10.0 μm or less. If the thickness is less than 0.5 μm, the wear resistance and the fracture resistance may decrease. On the other hand, if it exceeds 10.0 μm, an abnormal defect may occur.

(6) The coating film further comprises Group 4 elements (Ti, Zr, Hf, etc.), Group 5 elements (V, Nb, Ta, etc.), Group 6 elements (Cr, Mo, W, etc.), Al, and Al. One layer containing at least one element selected from the group consisting of Si, or a compound having the at least one element and at least one element selected from the group consisting of C, N, O and B. It is preferable to provide more than one layer. When such a compound layer exists between the base material and the laminated structure, the adhesion between the base material and the coating film is improved. Further, when such a compound layer is present on the surface side of the laminated structure, the wear resistance, adhesion resistance and fracture resistance of the surface-coated cutting tool are further improved.

(7) The base material preferably contains at least one selected from the group consisting of cemented carbide, cermet, cubic boron nitride sintered body, high-speed steel, ceramics and diamond sintered body. According to this, the surface coating cutting tool is extremely used as, for example, a drill, an end mill, a cutting tip with a replaceable cutting edge for milling or turning, a metal saw, a gear cutting tool, a reamer, a tap, or a tip for pin milling of a crank shaft. It can be used usefully.

[Details of Embodiments of the present invention]
A specific example of the surface-coated cutting tool according to the embodiment of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

<Embodiment 1>
(Surface coating cutting tool)
As shown in FIGS. 1 and 2, the surface-coated cutting tools 10 and 11 include a base material 1 and a coating film 5 formed on the base material 1, and the coating film 5 includes layers A 2 and B. A laminated structure 8 in which layers 3, C layers 4 and D layers 9 are repeatedly laminated in this order is included.

The surface-coated cutting tool of the present embodiment is extremely used as, for example, a drill, an end mill, a cutting tip with a replaceable cutting edge for milling or turning, a metal saw, a gear cutting tool, a reamer, a tap, or a tip for pin milling of a crank shaft. It can be used usefully.

(Base material)
As the base material 1, a conventionally known base material known as a base material for a cutting tool can be used without particular limitation. For example, cemented carbide (for example, WC-based cemented carbide, WC, as well as those containing Co or further added with carbonitrides such as Ti, Ta, Nb), cermet (TiC, TiN, TiCN, etc.), cermet, etc. (Main component), cubic boron nitride sintered body, high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and mixtures thereof, etc.), diamond sintered body Etc. can be mentioned as an example of such a base material.

When a cemented carbide is used as the base material, the effect of the present invention is exhibited even if such a cemented carbide contains an abnormal phase called a free carbon or an η phase in the structure. The base material used in the present invention may have a modified surface. For example, in the case of cemented carbide, a deβ layer may be formed on the surface thereof, or in the case of cermet, a surface hardened layer may be formed, and even if the surface is modified in this way, the present invention The effect is shown.

(Coating)
The coating film 5 includes any aspect of covering the entire surface of the substrate, a mode in which the coating film is not partially formed, and a mode in which a part of the coating film is partially laminated differently.

The coating film 5 includes a laminated structure 8 in which A layer 2, B layer 3, C layer 4 and D layer 9 are repeatedly laminated in this order. If the A layer, the B layer, the C layer and the D layer are repeatedly laminated in this order in the laminated structure, any of the A layer, the B layer, the C layer and the D layer is arranged on the side in contact with the base material. It doesn't matter. That is, in the coating film, the A layer, the B layer, the C layer and the D layer may be repeatedly laminated in this order from the base material side. Further, in the coating film, the A layer, the B layer, the C layer and the D layer may be repeatedly laminated in this order from the surface side opposite to the substrate.

For example, as shown in FIG. 1, the A layer 2 is arranged in contact with the base material 1, and the B layer 3, the C layer 4 and the D layer 9 are arranged in this order on the A layer 2, and the D layer is arranged. Further, A layer 2, B layer 3, C layer 4 and D layer 9 may be further arranged on the layer 9 in this order (form (a)). Further, as shown in FIG. 2, the D layer 9 is arranged in contact with the base material 1, and the C layer 4, the B layer 3 and the A layer 2 are arranged in this order on the D layer 9, and the A layer is arranged. Layer D 9, C layer 4, B layer 3 and A layer 2 may be further arranged on the layer 2 in this order (form (b)). Further, although not shown in the figure, each layer may be arranged as in the following forms (c) to (h).

Form (c): A layer is arranged in contact with a base material, and a D layer, a C layer, a B layer and an A layer are arranged in this order on the A layer.

Form (d): A form in which a B layer is arranged in contact with a base material, and a C layer, a D layer, an A layer, a B layer, a C layer, and a D layer are arranged in this order on the B layer.

Form (e): A form in which a B layer is arranged in contact with a base material, and an A layer, a D layer, a C layer, a B layer, and an A layer are arranged in this order on the B layer.

Form (f): A form in which the C layer is arranged in contact with the base material 1, and the D layer, the A layer, the B layer, the C layer and the D layer are arranged in this order on the C layer.

Form (g): A form in which the C layer is arranged in contact with the base material 1, and the B layer, the A layer, the D layer, the C layer, the B layer and the A layer are arranged in this order on the C layer.

Form (h): A form in which a D layer is arranged in contact with a base material 1, and an A layer, a B layer, a C layer, and a D layer are arranged in this order on the D layer.

The laminated structure may have a form including two or more unit layers including one layer each of A layer, B layer, C layer and D layer. Further, one unit layer may be combined with one or more of the A layer, the B layer, the C layer and the D layer.

The surface layer on the opposite side to the base material of the laminated structure may be any of A layer, B layer, C layer, and D layer.

Each of the A layer 2, the B layer 3, the C layer 4 and the D layer 9 is selected from the group consisting of group 4 elements, group 5 elements, group 6 elements, Al, Si, B and Y of the periodic table at least 2. It is a nitride of elements above the species. Specifically, AlCrN, AlCrSiN, AlCrHfN, CrSiN, CrAlN, CrTiN, TiAlN, TiSiN, TiTaN, TiWN, TiNbN, TiZrN, TiBN, TimoN, TiHfN, TiAlYN, AlCrYN and the like can be used.

In the present specification, when a compound is represented by a chemical formula as described above, if the atomic ratio is not particularly limited, it shall include all conventionally known atomic ratios, and is not necessarily limited to those in the stoichiometric range. .. For example, when simply writing "AlCrN", the atomic ratio of "Al", "Cr" and "N" is not limited to 25:25:50, and when writing "CrN", "Cr" and "N" are also used. The atomic ratio of "" is not limited to the case of 50:50, and any conventionally known atomic ratio is included.

The composition of the compounds constituting each layer can be confirmed by TEM-EDX (energy dispersive X-ray spectroscopy). In TEM-EDX, for example, the following conditions can be preferably used.

<Measuring equipment>
Measuring equipment: VG, HB501
EDX: KEVEX Super8000 Quantitative Total System Energy Dispersive X-ray Analyzer (Si <Li> Semiconductor Detector, UTW Type)
EELS: VG, ELS-80 spectrometer (energy resolution: 0.56 eV)
<Measurement conditions>
Acceleration voltage: 100kV
Sample absorption current: 10 ^-9 A
Counting time: 50 to 100 seconds Analytical probe diameter: 1 nmφ

In the laminated structure 8, it is preferable that the layers containing Si are not adjacent to each other. According to this, the surface coating cutting tool can exhibit excellent fracture resistance. Since the crystallinity of the layer containing Si tends to decrease and the structure tends to be miniaturized, if the layers containing Si are adjacent to each other, the continuity of the lattice cannot be maintained and the fracture resistance may decrease. ..

The B layer and the D layer preferably have the same composition. According to this, the fracture resistance is improved. The reason for this is not clear, but it is presumed that the overall strain balance of the laminated structure is improved.

Lattice constant _L A of the A layer 2, the lattice constant _L B of the B layer 3, the lattice constant _{L D} lattice constant _{L C} and D layer 9 of C layer 4 has the following formula (I) and related formula (II) Meet.

_{L A} <L B <L _C Formula (I)
_{L A} <L D <L _C formula (II)

Lattice constant _{L A,} the lattice constant _{L B,} the lattice constant _{L C} and a lattice constant _{L D} satisfies the relationship of formula (I) and (II), and the difference in lattice constant between adjacent layers is more 0.0500A 0 When it is .1000 Å or less, the difference in lattice constant between adjacent layers can be reduced in the laminated structure 8, so that adjacent layers can exhibit high adhesion to each other.

Moreover, filled lattice constant _{L A,} the lattice constant _{L B,} the relationship between the lattice constant _{L C} and a lattice constant _{L D} is the formula (I) and (II), and a lattice constant _{L A,} the lattice constant _{L B,} the lattice constant L _C and the maximum value of the difference between the two lattice constants selected from the lattice constant L _D by not more than 0.1500Å least 0.1100A, since it increases the difference in lattice constant between the layers not adjacent, stacked structure As a whole, it is possible to obtain excellent fracture resistance.

In the laminated structure 8, the difference in lattice constant between adjacent layers is 0.0500 Å or more and 0.1000 Å or less. A difference in lattice constant between adjacent layers, the difference between the lattice constant L _B of the lattice constant of the layer A 2 L _A and B layer 3, the lattice constant L _C of the lattice constant of the B layer 3 L _B and C layer 4 difference, the difference between the lattice constant L _D lattice constant L _C and D layer 9 of C layer 4, and, means the difference between the lattice constant L _D and a layer 2 lattice constant L _a of the D layer 9. This makes it possible for the surface-coated cutting tool to exhibit excellent fracture resistance in high-speed, high-efficiency machining with a high heat load. The reason for this is not clear, but if the lattice constant difference between adjacent layers is 0.0500 Å or more, both strains at the time of lattice matching are sufficient, so that the fracture resistance is improved and the lattice constant difference is 0.1000 Å. It is presumed that the following is because the crystal lattice shows continuity at the interface between adjacent layers and the adhesion between adjacent layers is improved. The difference in lattice constant between adjacent layers is preferably 0.0550 Å or more and 0.0900 Å or less, and more preferably 0.0600 Å or more and 0.0700 Å or less.

Here, it can be confirmed by a transmission electron microscope (TEM) that the crystal lattice shows continuity at the interface between adjacent layers. Specifically, it can be determined that the crystal lattice shows continuity when the lattices of each layer are connected at the interface between the layers. In this TEM analysis, for example, the following conditions can be preferably used.

<TEM analysis conditions>
Measuring equipment: Made by Hitachi, Product name: H-9000UHR
Acceleration voltage: 300kV
Magnification: 200,000-8 million times

In the laminated structure 8, the lattice constant _{L A,} the lattice constant _{L B,} the maximum value of the difference between the two lattice constants selected from the lattice constant _{L C} and a lattice constant _{L D} is less than 0.1500Å least 0.1100A. The maximum value of the difference in lattice constant, the lattice constant L _A, the lattice constant L _B, among the lattice constant L _C and a lattice constant L _D, means the difference between the minimum value of the maximum value and the lattice constants. This makes it possible for the surface-coated cutting tool to exhibit excellent fracture resistance in high-speed, high-efficiency machining with a high heat load. This is because when the maximum value of the lattice constant difference is 0.1100 Å or more, the lattice strain inside the laminated structure is sufficient and the fracture resistance is improved, and when the lattice constant difference is 0.1500 Å or less, each layer. It is presumed that this is because the cubic crystal structure at the interface of the above surface has good crystallinity and therefore the fracture resistance is improved. The maximum value of the difference in lattice constant is preferably 0.1200 Å or more and 0.1350 Å or less.

Here, the "lattice constant" uses any of the following values.
(1) When the material of each layer is described on the JCPDS card (JCPDS: Joint Committee on Powerfraction Standards), the value of the lattice constant described.
(2) When the material of each layer is a composite of the materials described on the JCPDS card, the lattice constant was calculated using the lattice constant described on the JCPDS card of each material and the composition ratio of the composite. value. For example, the lattice constant L _TiCrN of Ti _A Cr _1- AN (0 <A <1) is described in the JCPDS card as the lattice constant L _TiN (4.23 Å) of _TiN described in the JCPDS card. Using the lattice constant L _CrN (4.16 Å) of _CrN , it is obtained as follows.
L _TiCrN = L _TiN · A + L _CrN (1-A) = (L _TiN −L _CrN ) × A + L _CrN = (4.239-4.136) × A + 4.136 [Å]
(3) If the lattice constant cannot be calculated from (2) above, each layer is formed on a substrate (K10 cemented carbide (JIS)) under the following conditions by the arc ion plating method, and X A value obtained by calculating the lattice constant from the peak angle of the θ / 2θ method of the line analysis method (XRD). In the arc ion plating method, N ₂ gas is introduced so that the pressure in the chamber becomes 4.0 Pa, the substrate temperature is 600 ° C., the arc current is 150 A, the bias voltage is -15 V, and the film thickness is 2.0 μm. The film is formed until it becomes. After film formation, the film is heated in a high temperature XRD at 650 ° C. in vacuum until the peak position stabilizes, and then the peak angle is measured after the peak position stabilizes.

It is preferable that the A layer, the B layer, the C layer and the D layer each have a layer thickness of 1 nm or more and 110 nm or less. If the layer thickness is less than 1 nm, the laminated structure is almost eliminated due to the diffusion of elements between the layers, a mixed layer is formed, and the fracture resistance may be lowered. On the other hand, if the layer thickness exceeds 110 nm, a region having a small lattice strain is formed in the laminated structure, and the fracture resistance may be lowered. The layer thickness of each of the A layer, B layer, C layer and D layer is preferably 1 nm or more and 50 nm or less, more preferably 3 nm or more and 20 nm or less, and further preferably 6 nm or more and 12 nm or less.

The laminated structure preferably has a total thickness of 0.5 μm or more and 10.0 μm or less. If the total thickness of the laminated structure is less than 0.5 μm, the wear resistance and the fracture resistance may decrease. On the other hand, if it exceeds 10.0 μm, an abnormal defect may occur. The total thickness of the entire laminated structure is more preferably 1.0 μm or more and 6.0 μm or less, and further preferably 1.5 μm or more and 4.0 μm or less.

Here, the "layer thickness of each layer" or the "overall thickness of the laminated structure" is obtained as follows. First, a measurement sample including a cross section parallel to the normal direction of the surface of the base material is prepared. Next, the cross section is observed with a scanning transmission electron microscope (STEM), and the magnification is adjusted so that the observed image includes the entire area in the thickness direction of the coating film. Then, the thickness is measured at 5 points or more, and the average value is taken as the thickness. In STEM, for example, the following conditions can be preferably used.

<STEM analysis conditions>
Measuring equipment: Made by Hitachi, Product name: HD-2700
Acceleration voltage: 200kV
Magnification: 200,000-8 million times

The number of layers A, B, C, and D in the laminated structure is naturally determined when the total thickness of the laminated structure and the thickness of each of these layers are determined, but 6 or more layers are used. Preferably, 10 or more layers are more preferable.

Each of the A layer, the B layer, the C layer and the D layer has a cubic crystal structure. The crystal structure can be analyzed by a TEM (transmission electron microscope) diffraction pattern. When the material of each layer has a cubic crystal structure, a surface-coated cutting tool having excellent hardness, heat resistance, oxidation resistance, and chemical stability can be obtained.

(Production method)
In order to form (deposit) the laminated structure on the surface of the substrate, it is preferable that the film forming process is capable of forming a compound having a cubic crystal structure. Specifically, it is preferable to use a physical vapor deposition method.

As the physical vapor deposition method, a sputtering method, an ion plating method and the like are known, and any of such conventionally known physical vapor deposition methods can be adopted. Above all, it is preferable to adopt the cathode arc ion plating method in which the ion ratio of the raw material element is high. By adopting the cathode arc ion plating method, it is possible to perform metal or gas ion bombardment treatment on the surface of the base material before forming the film, which dramatically improves the adhesion of the film. Can be done.

As the conditions of the cathode arc ion plating method, conventionally known conditions can be adopted without particular limitation.

<Embodiment 2>
(Surface coating cutting tool)
As shown in FIG. 3, the surface-coated cutting tool 12 may have an intermediate layer 6 between the base material 1 and the laminated structure 8. Further, as shown in FIG. 3, the surface-coated cutting tool 12 may have a surface layer 7 on the surface opposite to the substrate of the laminated structure 8. Further, although not shown in the drawing, the surface coating cutting tool may have an intermediate layer between the laminated structure and the surface layer. As described above, the coating film 5 can include the intermediate layer 6, the surface layer 7, and the laminated structure 8.

The intermediate layer 6 and the surface layer 7 are composed of at least one element selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Al and Si in the periodic table, or at least one element. It preferably contains a compound having at least one element selected from the group consisting of C, N, O and B. When the intermediate layer contains the compound, the adhesion strength between the base material and the laminated structure or the laminated structure and the surface layer is improved, and peeling of both can be suppressed. When the surface layer contains the compound, the wear resistance of the surface coating cutting tool is improved. The intermediate layer and the surface layer may each be composed of one layer, or each may be composed of two or more layers.

As the compound, for example, TiWCN, TiNbN, CrWCN, TiCN, AlN, TiAlSiN, TiWCNO, TiAlBN and the like can be used.

The intermediate layer and the surface layer may be composed of a single layer, or may have a multi-layer structure in which different compounds are laminated.

The layer thickness of the intermediate layer is preferably 1 nm or more and 500 nm or less from the viewpoint of adhesion and productivity. The thickness of the surface layer is preferably 0.1 μm or more and 5 μm or less from the viewpoint of wear resistance and adhesiveness.

The present embodiment will be described in more detail with reference to Examples. However, these embodiments do not limit the present embodiment. The layer thickness of each layer or the thickness of the entire laminated structure in the examples is measured by observing the cross section of each layer or the entire laminated structure using a TEM (transmission electron microscope), and the composition of the compounds constituting each layer. Was confirmed by TEM-EDX (energy dispersive X-ray spectroscopy). The crystal structure and lattice continuity were analyzed by TEM (transmission electron microscope) diffraction pattern and lattice image. As described above, the lattice constant of each layer is (1) the value of the lattice constant described on the JCPDS card, (2) the value calculated from the lattice constant described on the JCPDS card, or (3) from the desired material. The layer was formed under predetermined conditions, and the lattice constant was calculated from the peak angle of the θ / 2θ method of the X-ray analysis method (XRD). For the lattice constant difference, 4 significant figures (4 digits after the decimal point) were used.

<Manufacturing of surface coating cutting tools>
In this example, a surface-coated cutting tool was prepared as follows, and a turning test and a milling test were performed to evaluate the performance.

(Samples 1-38, 43-46)
As a base material for a surface-coated cutting tool, a cutting tip with a replaceable cutting edge for turning, which is made of K20 cemented carbide (JIS) and has a shape of CNMG120408 (JIS), was prepared for the turning test. For the milling test, a milling cutting edge exchangeable cutting tip having a material of P20 cemented carbide (JIS) and a shape of SEET13T3AGSN (JIS) was prepared.

Next, a film was formed on the substrate. Specific formation conditions are shown below by taking Sample 1 shown in Table 1 as an example.

As target materials, an alloy in which Al is 80 atomic% and Cr is 20 atomic% (target for forming the A layer) and an alloy in which Ti is 45 atomic% and Al is 55 atomic% (for forming the B layer). (Target), an alloy containing 95 atomic% of Ti and 5 atomic% of Si (target for forming the C layer), and an alloy containing 50 atomic% of Ti and 50 atomic% of Al (for forming the D layer). Target) was prepared. In addition, although all target materials contain a small amount of unavoidable impurities, the notation excludes them.

The substrate was mounted on a cathode arc ion plating sputtering apparatus. The surface of the base material was cleaned for 15 minutes by introducing Ar gas into the chamber, maintaining the pressure in the chamber at 3.0 Pa, and gradually increasing the bias voltage to −1000 V. After that, Ar gas was exhausted. As a result, Ar ions cleaned the surface of the base material to remove strong stains and oxide film.

Next, layer A is formed on the base material. That is, N ₂ gas was introduced so that the pressure in the chamber was 5.0 Pa, the base material temperature was set to 500 ° C., and the base material bias voltage was set to 65 V. The target for forming the A layer was ionized by arc discharge and reacted with N ₂ gas to form the A layer having a layer thickness of 24 nm composed of cubic Al _0.8 Cr _0.2 N so as to be in contact with the base material. ..

Subsequently, the B layer is formed on the A layer. That is, N ₂ gas was introduced so that the pressure in the chamber was 5.0 Pa, the base material temperature was set to 500 ° C., and the base material bias voltage was set to 65 V. The target for forming the B layer was ionized by an arc discharge and reacted with N ₂ gas, whereby the B layer having a layer thickness of 20 nm composed of cubic Ti _0.45 Al _0.55 N was laminated on the A layer.

Subsequently, a C layer is formed on the B layer. That is, N ₂ gas was introduced so that the pressure in the chamber was 5.0 Pa, the base material temperature was set to 500 ° C., and the base material bias voltage was set to 65 V. By ionizing the C layer forming target by arc discharge and reacting with N ₂ gas, a C layer having a layer thickness of 22 nm composed of cubic Ti _0.95 Si _0.05 N was laminated on the B layer.

Subsequently, a D layer is formed on the C layer. That is, N ₂ gas was introduced so that the pressure in the chamber was 5.0 Pa, the base material temperature was set to 500 ° C., and the base material bias voltage was set to 65 V. The target for forming the D layer was ionized by an arc discharge and reacted with N ₂ gas, whereby a D layer having a layer thickness of 21 nm composed of cubic Ti _0.50 Al _0.50 N was laminated on the C layer.

Next, the A layer, the B layer, the C layer and the D layer were repeatedly laminated on the D layer in this order in the same manner as described above. As a result, a surface-coated cutting tool in which a coating having a laminated structure having an overall layer thickness of 3.0 μm was formed on the base material was obtained.

Samples 2-38, 43-46 are the same as Sample 1 except that the target material and sputtering conditions are appropriately changed so that the A layer, the B layer and the C layer have the composition and layer thickness shown in Table 1, respectively. It was prepared by the method of. That is, the base material is mounted on a cathode arc ion plating sputtering device, N ₂ gas is introduced so that the pressure in the chamber becomes 1.6 Pa to 5.0 Pa, and the base material temperature is 430 ° C. to 620 ° C. The substrate bias voltage was set to 15V to 150V. A target having a desired composition was ionized by arc discharge and reacted with N ₂ gas to prepare A layer, B layer, C layer and D layer, respectively, having desired thicknesses. The stacking order of the A layer, the B layer, the C layer and the D layer on the base material is described in the column of "Layering order on the base material" in Table 1. For example, in sample 2, a D layer is formed on a base material, a C layer, a B layer, and an A layer are laminated in this order on the D layer, and then the D layer, the C layer, and the like are further laminated on the A layer. The B layer and the A layer were repeatedly laminated in this order.

(Samples 39 to 42)
A substrate similar to that of Sample 1 was prepared. Next, the intermediate layer, the laminated structure and the surface layer were laminated in this order on the base material to form a coating film. As for the method of forming the intermediate layer, the laminated structure and the surface layer, the sample was obtained by appropriately changing the target material and the sputtering conditions so that the intermediate layer, the laminated structure and the surface layer had the composition and the layer thickness shown in Table 1, respectively. It was prepared in the same manner as in 1.

The surface layer of sample 42 has a super-multilayer structure, which was prepared under conventionally known conditions. That is, using a target having a target composition (composition shown in Table 1), N ₂ gas is introduced so that the pressure in the chamber becomes 2.6 Pa, the substrate temperature is 550 ° C, and the substrate bias voltage is 40 V. By repeating the operation of forming a TiAlSiN layer at 15 nm and the operation of forming a TiNbN layer at 10 nm with a substrate temperature of 550 ° C and a substrate bias voltage of 40 V, an ultra-multilayer structure having an overall thickness of 1.0 μm is formed. Was produced.

<Performance evaluation>
The fracture resistance of each of the surface-coated cutting tools of Samples 1 to 46 prepared above was evaluated by performing a turning test and a milling test under high-speed, high-efficiency machining conditions with a high heat load. The specific conditions of the turning test and the milling test are as follows.

(Turning test)
Work Material: Inconel 718 Round Bar Cutting Speed: 75m / min Cutting: 2.0mm
Feed: 0.25 mm / rev
DRY / WET: WET

The evaluation was performed by measuring the time until a defect occurs in the surface coating cutting tool as the cutting time. The results are shown in Table 2. A long cutting time indicates excellent fracture resistance.

Samples 1 to 42 have excellent resistance, with the difference in lattice constant between adjacent layers being 0.0500 Å or more and 0.1000 Å or less, and the maximum value of the difference in lattice constant being 0.1100 Å or more and 0.1500 Å or less. It showed deficiency. In sample 43, the difference in lattice constant between adjacent layers was out of the range of 0.0500 Å or more and 0.1000 Å or less, and the fracture resistance was inferior. In Samples 44 to 46, at least one of the differences in lattice constant between adjacent layers is outside the range of 0.0500 Å or more and 0.1000 Å or less, and the maximum value of the difference in lattice constant is 0.1100 Å or more and 0.1500 Å or less. It was out of the following range and had poor fracture resistance.

(Milling test)
Work material: SCM435
Cutting speed: 270 m / min Cutting: 1.5 mm
Feed: 0.2mm / rev
DRY / WET: DRY

The evaluation was carried out by measuring the time until the amount of wear on the flank of the surface-coated cutting tool reaches 0.2 mm or the time until a defect occurs as the cutting time. The results are shown in Table 3. A long cutting time indicates excellent fracture resistance.

Samples 1 to 42 have excellent resistance, with the difference in lattice constant between adjacent layers being 0.0500 Å or more and 0.1000 Å or less, and the maximum value of the difference in lattice constant being 0.1100 Å or more and 0.1500 Å or less. It showed deficiency. In sample 43, the difference in lattice constant between adjacent layers was out of the range of 0.0500 Å or more and 0.1000 Å or less, and the fracture resistance was inferior. In Samples 44 to 46, at least one of the differences in lattice constant between adjacent layers is outside the range of 0.0500 Å or more and 0.1000 Å or less, and the maximum value of the difference in lattice constant is 0.1100 Å or more and 0.1500 Å or less. It was out of the following range and had poor fracture resistance.

The embodiments and examples disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims rather than the above-described embodiment, and is intended to include meaning equivalent to the scope of claims and all modifications within the scope.

1 base material, 2 A layer, 3 B layer, 4 C layer, 5 coating, 6 intermediate layer, 7 surface layer, 8 laminated structure, 9 D layer, 10, 11, 12 surface coating cutting tool

Claims (7)

A surface-coated cutting tool comprising a base material and a coating formed on the base material.
The coating includes a laminated structure in which A layer, B layer, C layer and D layer are repeatedly laminated in this order.
Each of the A layer, the B layer, the C layer and the D layer is selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Al, Si, B and Y in the periodic table. It is a nitride of more than a species of element,
Lattice constant _{L A} of the A layer, the lattice constant _{L B} of the B layer, the lattice constant _{L D} lattice constant _{L C} and the D layer of the layer C, the following formula (I) and related formula (II) The filling,
_{L A} <L B <L _C Formula (I)
_{L A} <L D <L _C formula (II)
In the laminated structure, the difference in lattice constant between adjacent layers is 0.0500 Å or more and 0.1000 Å or less.
The lattice constant _{L A,} the lattice constant _{L B,} the maximum value of the difference between the two lattice constants chosen from among the lattice constant _{L C,} and the lattice constant _{L D} is less 0.1500Å least 0.1100A,
Each of the A layer, the B layer, the C layer and the D layer has a cubic crystal structure.
Surface coating cutting tool. The surface coating cutting tool according to claim 1, wherein the layers containing Si are not adjacent to each other in the laminated structure. The surface-coated cutting tool according to claim 1 or 2, wherein each of the A layer, the B layer, the C layer, and the D layer has a layer thickness of 1 nm or more and 110 nm or less. The surface-coated cutting tool according to any one of claims 1 to 3, wherein the B layer and the D layer have the same composition. The surface-coated cutting tool according to any one of claims 1 to 4, wherein the laminated structure has a total thickness of 0.5 μm or more and 10.0 μm or less. The film is further formed by at least one element selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Al and Si in the periodic table, or at least one element and C, N, The surface coating cutting tool according to any one of claims 1 to 5, further comprising one or more layers containing a compound having at least one element selected from the group consisting of O and B. The base material comprises at least one selected from the group consisting of cemented carbide, cermet, cubic boron nitride sintered body, high-speed steel, ceramics and diamond sintered body, claims 1 to 6. The surface coating cutting tool according to any one of the above items.

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