JP7389948B2 - A surface-coated cutting tool with a hard coating layer that exhibits excellent chipping resistance. - Google Patents

Description

The present invention is a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance over a long period of use because the hard coating layer has excellent chipping resistance even when used for high-speed interrupted cutting of cast iron, etc. ).

Conventionally, there are coated tools in which a Ti-Al-based composite carbonitride layer is formed as a hard coating layer on the surface of a tool base made of tungsten carbide (hereinafter referred to as WC)-based cemented carbide. It is known to exhibit excellent wear resistance.
However, although the conventional coated tool coated with a Ti-Al based composite carbonitride layer has relatively excellent wear resistance, it can cause abnormal wear such as chipping when used under high-speed interrupted cutting conditions. Because of its ease of use, various proposals have been made for improving the hard coating layer.

For example, Patent Document 1 discloses a tool coated with a titanium aluminum nitride film, in which a tool base is provided with a coating layer consisting of one layer or multiple layers, and at least one layer of the coating layer is a titanium aluminum nitride film containing at least titanium, aluminum, and nitrogen. A tool coated with a titanium aluminum nitride film is described, wherein the titanium aluminum nitride film has a cubic crystal structure, has tensile residual stress, and has a chlorine content of 0.01 to 2% by mass. There is.

For example, Patent Document 2 describes a multilayer structure in which a first unit layer made of Ti _1-x Al _x N and a second unit layer made of Ti _1-y Al _y N are alternately laminated as a plurality of layers. The first unit layer has an FCC type crystal structure, and 0<x<0.65, and the second unit layer has an HCP type crystal structure, and 0.65≦y<1. A coated tool is described that has a coating, and each of the first unit layer and the second unit layer has a thickness of 3 nm or more and 30 nm or less.

Further, for example, Patent Document 3 discloses that the crystal grains include a plurality of crystal grains and an amorphous phase between the crystal grains, and each of the crystal grains is a Ti _1-x Al _x N layer having an fcc structure. It has a structure in which Ti _1-y Al _y N layers having an hcp structure are alternately stacked, and 0≦x<1, 0<y≦1, (y-x)≧0.1. satisfying the relationship, the amorphous phase includes a carbide, nitride, or carbonitride of at least one of Ti and Al, and the thickness per layer of the adjacent Ti _1-x Al _x N layers and the Ti _{1 -y} Al _y A coated tool having a hard coating having a total thickness of 1 nm or more and 50 nm or less, including the thickness per layer, is described.

In addition, for example, Patent Document 4 discloses a lower layer consisting of a titanium aluminum nitride film mainly having an FCC structure with a thickness of 2 to 15 μm, and an upper layer consisting of an aluminum nitride film having an HCP structure with a thickness of 0.2 to 10 μm. The upper layer has a columnar crystal structure, the columnar crystals have an average cross-sectional diameter of 0.05 to 0.6 μm, and the upper layer has an X-ray diffraction peak value of the (100) plane. The upper layer is composed of a hard coating in which the ratio of the X-ray diffraction peak value Ia (002) of the (002) plane to the Ia (100) satisfies the relationship Ia (002)/Ia (100)≧6, and the upper layer is the lower layer. A coated tool is described which is characterized by epitaxial growth thereon.

Japanese Patent Application Publication No. 2001-341008 Japanese Patent Application Publication No. 2015-124407 Unexamined Japanese Patent Publication No. 2016-3369 International Publication 2018/008554

However, when the coated tools described in Patent Documents 1 to 4 are used for high-speed interrupted cutting of cast iron, etc., abnormal damage such as thermal cracks occurs in the coating on the rake face of the coated tool, and this is the starting point. Chipping is likely to occur, and it cannot be said that satisfactory cutting performance is exhibited.

Therefore, an object of the present invention is to provide a coated tool that exhibits excellent cutting performance over a long period of use because the hard coating layer has excellent chipping resistance even when used for high-speed interrupted cutting of cast iron and the like. shall be.

The present inventor has developed a composite nitride layer or a composite layer containing Al and Me (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) as a hard coating layer. We conducted a thorough study on the occurrence of chipping caused by abnormal damage such as thermal cracks in the carbonitride layer (hereinafter, this composite nitride layer or composite carbonitride layer is also referred to as the AlMeCN layer), and found that it has good wear resistance. A composite nitride layer or composite carbonitride layer containing Al and Ti with a NaCl-type face-centered cubic structure (sometimes referred to as cubic structure) (hereinafter, this composite nitride layer or composite carbonitride layer will be referred to as an AlTiCN layer). An AlMeCN layer with a predetermined thickness close to the tool base (the layer on the tool base side) has a wurtzite hexagonal crystal structure (hexagonal crystal structure) with good lubricity and excellent heat crack resistance. It is said that chipping resistance can be improved in high-speed interrupted cutting of cast iron etc. by providing at least one laminated layer of a predetermined thickness on the side closer to the tool surface (the layer on the tool surface side). I gained new knowledge.

The present invention is based on this knowledge,
(1) A surface-coated cutting tool in which a hard coating layer is provided on the surface of the tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
A surface-coated cutting tool characterized in that xα and xβ satisfy |xβ−xα|≦0.04.
(2) The α layer contains a trace amount of Cl, and the content ratio zα of Cl in the total amount of C, N, and Cl (where zα is the atomic ratio) satisfies 0.0015≦zα≦0.0100. The surface-coated cutting tool according to ( 1 ), characterized in that:
(3) The β layer contains a trace amount of Cl, and the content ratio zβ of Cl in the total amount of C, N, and Cl (where zβ is an atomic ratio) satisfies 0.0001≦zβ≦0.0020. The surface-coated cutting tool according to (1) or (2), characterized in that:
(4) The rake face of the surface-coated cutting tool has the hard coating layer including the laminated structure of the α layer and the β layer, and the flank face has the hard coating layer including the β layer. The surface-coated cutting tool according to any one of (1) to ( 3 ).
(5) A surface-coated cutting tool in which a hard coating layer is provided on the surface of the tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
The α layer contains a trace amount of Cl, and the content ratio zα of Cl in the total amount of C, N, and Cl (where zα is the atomic ratio) satisfies 0.0015≦zα≦0.0100. surface-coated cutting tools.
(6) A surface-coated cutting tool in which a hard coating layer is provided on the surface of the tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
The β layer contains a trace amount of Cl, and the content ratio zβ of Cl in the total amount of C, N, and Cl (where zβ is an atomic ratio) satisfies 0.0001≦zβ≦0.0020. surface-coated cutting tools.
(7) A surface-coated cutting tool in which a hard coating layer is provided on the surface of the tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
A surface-coated cutting tool characterized in that the rake face of the surface-coated cutting tool has the hard coating layer including the laminated structure of the α layer and the β layer, and the flank face has the hard coating layer including the β layer. tool.
(8) The β layer contains a trace amount of Cl, and the content ratio zβ of Cl in the total amount of C, N, and Cl (where zβ is the atomic ratio) satisfies 0.0001≦zβ≦0.0020. The surface-coated cutting tool according to ( 5 ), characterized in that:
(9) The surface-coated cutting tool has the hard coating layer including the laminated structure of the α layer and the β layer on the rake face, and the hard coating layer including the β layer on the flank face. The surface-coated cutting tool according to any one of (5), (6), and (8) .
(10) In the case where xα and xβ are |xβ−xα|>0.04, a composite nitride or composite of Al and Ti mainly containing a cubic structure between the α layer and the β layer There is an AlTiCN layer δ containing at least carbonitride crystal grains,
(a) The AlTiCNδ layer has a region divided into two equal parts in the layer thickness direction.
When the composition of the region on the tool base side is expressed by the composition formula: (Al _xδL Ti _(1-xδL) ) (C _yδL N _(1-yδL) ), the average content ratio of Al to the total amount of Ti and Al xδL and the average content ratio yδL of C in the total amount of C and N (however, xδL and yδL are both atomic ratios),
Further, when the composition of the region on the tool surface side of the region bisected in the layer thickness direction is expressed by the composition formula: (Al _xδH Ti _(1-xδH) ) (C _yδH N _(1-yδH) ), The average content ratio xδH of Al in the total amount of Ti and Al, and the average content ratio yδH of C in the total amount of C and N (however, xδH and yδH are both atomic ratios),
xα≦xδH<xδL<xβ or xβ<xδL<xδH≦xα, and
satisfies 0.0000≦yδH≦0.0150 and 0.0000≦yδL≦0.0150,
(b) The TiAlCN layer δ satisfies 0.1 μm≦Lδ≦1.0 μm, where Lδ is the average layer thickness.
(11) The surface-coated cutting tool according to any one of ( 5 ) to ( 9 ), characterized in that the α layer has a hexagonal crystal structure when analyzed from a longitudinal section perpendicular to the surface of the tool base. Contains crystal grains of 70 area% or more and 95 area% or less,
The β layer contains 90 area % or more of crystal grains having a cubic crystal structure when analyzed from a longitudinal section perpendicular to the surface of the tool base.
The surface-coated cutting tool according to any one of items 1 to 10 , characterized in that: ”
It is.

The surface-coated cutting tool according to the present invention has an AlMeCN layer (α layer) mainly containing a hexagonal structure with low hardness on the tool surface side, and an AlTiCN layer (β layer) mainly containing a cubic structure with excellent hardness on the tool surface side. By providing at least one layer in which the It prevents damage to the surface and has a long service life even when cutting cast iron at high speed.

It is a schematic diagram which shows the hard coating layer when the layer which laminated|stacked an alpha layer and a beta layer is one layer. It is a schematic diagram of another embodiment of the hard coating layer of the surface-coated cutting tool according to the present invention, which has a δ layer between the α layer and the β layer.

Hereinafter, the coated tool of the present invention will be explained in more detail. In the present specification and claims, when a numerical range is expressed using "~", the range includes the upper and lower numerical limits.

Tool Base Any base material that is conventionally known as this type of tool base can be used as long as it does not interfere with achieving the object of the present invention. Examples include cemented carbide (WC-based cemented carbide, WC, and other materials containing Co, or containing carbonitrides such as Ti, Ta, and Nb), cermets (TiC, TiN , TiCN, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cBN sintered body, or diamond sintered body. Among these various base materials, it is particularly preferable to select WC-based cemented carbide, cermet (TiCN-based cermet), and cBN sintered body. The reason for this is that these materials have an excellent balance between hardness and strength at high temperatures and are excellent as tool bases for surface-coated cutting tools.

Structure of hard coating layer (overall structure)
As shown in FIG. 1, the coated tool according to the present invention has a hexagonal structure of Al and Me (where Me is one or more selected from Si, Zr, V, Cr, Nb, Hf, and Mn). The α layer (also referred to as α layer) of an AlMeCN layer containing at least crystal grains of a composite nitride or composite carbonitride of (element) is placed on the tool surface side, and a composite nitride or composite carbonitride of Al and Ti having a cubic structure is placed on the tool surface side. The tool has a hard coating layer including at least one layer in which a β layer (also referred to as β layer) of an AlTiCN layer containing at least crystal grains of a substance is laminated on the tool base side. The reason why the hard coating layer has such a structure is that the α layer, which has good lubricity and excellent heat cracking resistance, is placed on the tool surface side, and the β layer, which has good wear resistance, is placed on the tool base side. By doing so, it is possible to maintain wear resistance on the flank face, prevent thermal cracks from occurring on the rake face, and furthermore prevent damage from the rake face to the flank face, making it suitable for high-speed interrupted cutting of cast iron, etc. This is because excellent cutting performance can be exhibited over a long period of time.

Further, the hard coating layer may contain other layers as long as it has at least one layer in which the α layer and the β layer are laminated. As other layers, for example, in addition to the δ layer of AlTiCN, which will be described later, between the α layer and the β layer, a base layer that improves the adhesion between this laminated layer and the tool base is preferable. Furthermore, an upper layer provided on the laminated layer may be included as long as it does not promote wear and tear, such as chipping together with the laminated layer.
The base layer includes at least one of a Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitoxide layer, and the upper layer includes a Ti carbonitoxide layer and a Ti carbonitoxide layer. Examples include at least one layer of aluminum. The compositions of these layers are not necessarily limited to only the stoichiometric range, but include all conventionally known atomic ratios.

The average layer thickness of the entire hard coating layer, including the base layer and the upper layer, is preferably in the range of 1.5 to 25.0 μm, regardless of the presence or absence of the δ layer described below. The reason for this range is that if the thickness is less than 1.5 μm, the properties of the hard coating layer brought about by the characteristics of the α layer and β layer cannot be fully exhibited, while if it exceeds 25.0 μm, the chipping resistance will deteriorate. It will drop.
In addition, in the claims and this specification, the average layer thickness refers to the average thickness measured at the rake face.
Each layer will be explained in detail below.

1. α layer:
Although the α layer has low hardness, it has good lubricity and excellent heat cracking resistance, as shown below.

(1) Average layer thickness The average layer thickness Lα of the α layer is preferably 0.5 to 5.0 μm. The reason for this range is that if the average layer thickness is less than 0.5 μm, the hard coating layer will wear out early even on the rake face, and the effect of improving heat cracking resistance will not be exhibited. This is because the crystal grains in the α layer become larger and the chipping resistance of the α layer decreases.
Note that when there is a plurality of laminated layers of α layers and β layers, the thickness of each α layer may be the same or different as long as it falls within the above range.

(2) Crystal structure The α layer contains crystal grains of a composite nitride or carbonitride of Al and Me having a hexagonal crystal structure.
Here, when the α layer has a hexagonal crystal structure, it is preferable that the α layer has crystal grains with a hexagonal crystal structure in an area of 60% or more in the longitudinal section (cross section perpendicular to the tool base), and a non-woven material that provides lubricity to the hard coating layer. It may also contain a crystalline layer. When this area ratio is satisfied, the property that the α layer has good heat cracking resistance can be more reliably exhibited. Further, it is more preferable that crystal grains having a hexagonal crystal structure are contained in a range of 70 area % or more and 95 area % or less.

(3) Nanoindentation indentation hardness It is preferable that the nanoindentation indentation hardness Hα of the α layer is 15 GPa≦Hα≦28 GPa. The reason for choosing this range is that if it is less than 15 GPa, the wear resistance of the rake face will be insufficient and it will wear out early, and the heat cracking resistance will not be improved. On the other hand, if it exceeds 28 GPa, the lubricity will decrease and This is because the abrasion resistance increases and the heat cracking resistance decreases.
Note that the nanoindentation indentation hardness described in the claims and this specification was measured based on the provisions of ISO 14577.

(4) Composition When the composition of the α layer is expressed by the composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} ), the average content ratio of Al to the total amount of Me and Al and the average content ratio yα of C in the total amount of C and N (however, xα and yα are both atomic ratios) is 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150, respectively. It is preferable to satisfy the following.

The reason why the average content ratio of Al is set in this range is that if it is less than 0.70, the hexagonal crystal structure will not be stably formed and the heat cracking resistance will decrease, while if it exceeds 0.95, the rake surface will deteriorate. This is because the abrasion resistance of the material is insufficient and it wears out early, so that the effect of improving heat cracking resistance is not exhibited.
Furthermore, if the average content ratio of C is within this range, heat cracking resistance will be improved by improving lubricity, but if it deviates from this range, the hardness will decrease and the wear resistance of the rake face will be insufficient. This is because it wears out early and the effect of improving heat cracking resistance cannot be exhibited.

2. β layer:
The β layer is a layer with excellent hardness and is as follows.

(1) Average layer thickness The average layer thickness Lβ of the β layer is preferably 1.0 to 20.0 μm. The reason for this range is that if the average layer thickness is less than 1.0 μm, the layer thickness is too thin to ensure sufficient wear resistance over long-term use, while on the other hand, if the average layer thickness exceeds 20.0 μm This is because the crystal grains of the β layer tend to become coarser and chipping occurs more easily.
Note that when there is a plurality of laminated layers of α layers and β layers, the thickness of each β layer may be the same or different as long as it falls within the above range.

(2) Crystal Structure The β layer contains crystal grains of a composite nitride or carbonitride of Al and Ti having a NaCl-type face-centered cubic structure (cubic crystal structure).
Here, when the β layer has a cubic structure, it is preferable that the vertical section has crystal grains with a cubic crystal structure in an area of 70% or more.If this area ratio is satisfied, the β layer has good hardness and wear resistance. The characteristics of excellent properties can be more reliably exhibited. Further, it is more preferable that crystal grains having a cubic crystal structure are contained in an area of 90% or more.

(3) Nanoindentation indentation hardness It is preferable that the nanoindentation indentation hardness Hβ of the β layer is 30GPa≦Hβ≦45GPa. The reason for this range is that if it is less than 30 GPa, the wear resistance of the flank surface will be insufficient and its life will reach the end of its life prematurely, whereas if it exceeds 45 GPa, the toughness of the film will decrease and chipping will easily occur. be.

(4) Composition When the composition of the β layer is expressed by the composition formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _{1 - yβ} ), the average content ratio of Al to the total amount of Ti and Al xβ and the average content ratio yβ of C in the total amount of C and N (however, xβ and yβ are both atomic ratios) is 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150, respectively. It is preferable to satisfy the following.

The reason why the average content ratio of Al is set in this range is that if it is less than 0.65, the AlTiCN layer will be inferior in hardness and will not have sufficient wear resistance, whereas if it exceeds 0.95, the Ti content will be insufficient. This is because the ratio decreases and crystal grains with a hexagonal crystal structure are more likely to be contained, leading to a decrease in wear resistance.
The reason why the average C content is set within this range is that heat cracking resistance is improved by improving lubricity, but if it deviates from this range, hardness decreases and the wear resistance of the flank surface is impaired. This is because the tool wears out quickly even if it is insufficient, and the tool life ends quickly.

3. Difference in average Al content ratio between α layer and β layer:
The average content ratio xα of Al in the total amount of Me and Al in the α layer and the average content ratio xβ of Al in the total amount of Ti and Al in the β layer should satisfy |xβ−xα|≦0.04. is preferred.
The reason is that in order to ensure adhesion between the α layer and the β layer, it is desirable that the difference between xβ and xα be small, and if the absolute value of the difference is within this range, adhesion can be more reliably ensured. This is because it can be done.

3. δ layer:
In the case of |xβ−xα|>0.04, in order to improve the adhesion between the α layer and the β layer, AlTiCN having a NaCl type face-centered cubic structure (cubic crystal structure) is used between both layers. It is more preferable that it has a δ layer.

(1) Composition When the δ layer is divided into two equal parts in the layer thickness direction,
When _the composition of _the region on the tool base side is expressed _by the composition formula _: (Al And the average content ratio yδL of C in the total amount of C and N (however, xδL and yδL are both atomic ratios) is
When _the composition _{of the} region on the tool surface side is expressed _by the composition formula: (Al And the average content ratio yδH of C in the total amount of C and N (however, xδH and yδH are both atomic ratios) is
It is preferable that xα≦xδH<xδL<xβ or xβ<xδL<xδH≦xα, and 0.0000≦yδH≦0.0150 and 0.0000≦yδL≦0.0150, respectively. .

The reason why the composition of the δ layer is defined in this way is that by bringing xβ in the β layer closer to xδL in the δ layer, the adhesion between the β layer and the δ layer can be further improved. By bringing the xδH of the δ layer closer to the α layer, the adhesion with the α layer can also be improved, and the adhesion between the α layer and β layer can be improved through the δ layer, thereby increasing chipping resistance. It is.

(2) Average layer thickness of the δ layer The average layer thickness of the δ layer is 0.1 to 1.0 μm. The reason for this range is that if it is less than 0.1 μm, the average layer thickness of the δ layer will be too thin, and there will be a region of the β layer that is not sufficiently covered by the δ layer. If this is exceeded, the crystal grains in the δ layer will become coarse, and the initial nucleation of the crystal grains in the α layer will not be sufficient and the nucleation density will not be high, which is expected to improve the adhesion between the α and β layers. This is because it cannot be done.

4. Amount of chlorine contained in α layer and β layer The α layer and β layer may contain Cl as an impurity.
When the α layer contains Cl, it is preferable that the content ratio zα of Cl in the total amount of C, N, and Cl (where zα is an atomic ratio) satisfies 0.0015≦zα≦0.0010. The reason for this is that if it is less than 0.0015, the lubricity is insufficient and heat cracking resistance is reduced, while if it exceeds 0.0010, the hardness is reduced and the wear resistance of the rake face is insufficient and it wears out early. This is because the effect of improving heat cracking resistance cannot be exhibited.

When the β layer contains Cl, the content ratio zβ of Cl in the total amount of C, N, and Cl (where z is the atomic ratio) preferably satisfies 0.0001≦zβ≦0.0020. The reason for this is that if it is less than 0.0001, the lubricity is insufficient and wear resistance decreases, while if it exceeds 0.0020, the hardness decreases and the wear resistance of the flank surface is insufficient and it wears out early. This is because the product ends up reaching the end of its lifespan early.

5. A hard coating layer with a laminated structure including an α layer and a β layer on the rake face, and a hard coating layer including a β layer on the flank surface:
It is preferable that the rake face is provided with a hard coating layer having a laminated structure including an α layer and a β layer, and the flank surface is provided with a hard coating layer that does not contain an α layer but includes a β layer. Although an α layer may be provided on the flank surface, it is better not to have an α layer with low wear resistance on the surface of the flank surface that rubs most against the workpiece, since the underlying β layer is This prevents the tool from falling off, further improving tool life.

6. Measurement of the average layer thickness, composition, and crystal structure (area ratio) of the α layer, β layer, and δ layer First, the hard coating layer was polished using a focused ion beam system (FIB) and a cross section polisher (CP). Polisher) etc. to create a polished longitudinal section, and in this longitudinal section, the vertical direction (layer thickness direction) is the layer thickness of the hard coating layer, and the horizontal direction is a 100 μm square parallel to the tool base as the measurement area. Using an electron backscatter analyzer (EBSD), the measurement area was irradiated with an electron beam at an incident angle of 70 degrees and an acceleration voltage of 15 kV at an irradiation current of 1 nA at intervals of 0.01 μm. By analyzing the crystal structure of individual crystal grains based on the electron beam backscatter diffraction image obtained, boundaries between regions with different crystal structures are defined.

Furthermore, the α layer, β layer, Differentiate the δ layer. When a δ layer is included between the α layer and the β layer, a gradient change or a step change in the average content ratio of Al is observed (the boundary between the α layer and the δ layer is also determined by the presence or absence of Ti or the Me component). can be differentiated). Note that when the δ layer is not included between the α layer and the β layer, the boundary between the regions having different crystal structures becomes the boundary between the α layer and the β layer.

In analysis using an electron beam backscatter analyzer (EBSD), grain boundaries are defined as locations where there is an orientation difference of 5 degrees or more between adjacent measurement points (pixels). However, a single pixel that has an orientation difference of 5 degrees or more from all adjacent pixels is not treated as a crystal grain, and a pixel that is connected to two or more pixels is treated as a crystal grain. By determining each crystal grain and identifying its crystal structure in this manner, the area ratio of crystal grains having a hexagonal crystal structure or a cubic crystal structure in the layer thickness direction is determined.

Once the boundaries of each layer are defined, the average layer thickness can be determined between the defined boundary areas of each layer, and the average content ratio of Al in the α layer, β layer, and δ layer (xα, xβ, xδL, xδH ) can be determined by averaging the analysis results obtained by irradiating an electron beam using the Auger electron spectroscopy (AES) and analyzing multiple lines (for example, 5 or more lines) in the layer thickness direction. can.

Further, the average C content ratio (yα, yβ, yδL, yδH) of the α layer, β layer, and δ layer can be determined for each layer by secondary ion mass spectrometry (SIMS). That is, the content ratio in the depth direction is measured by alternately repeating surface analysis using an ion beam and etching using a sputtered ion beam. Specifically, in each layer, measurements were taken at a length of at least 0.05 μm at a pitch of 0.01 μm or less in the layer thickness direction from the point where the penetration was 0.05 μm or more, and the average value was determined. The average value calculated by checking each layer is determined as the average content ratio of C in each layer.

7. Production method:
The hard coating layer of the present invention is, for example, a base layer of a tool base or at least one of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitoxide layer on the tool base. For example, this can be obtained by supplying two reactive gases consisting of gas group A and gas group B having the following compositions with a predetermined phase difference.

As an example of the gas composition of the reaction gas, % is volume % (the sum of gas group A and gas group B is the total),
(1) Reactive gas for α layer formation Gas group A: NH ₃ : 4.0 to 10.0%, H ₂ : 40 to 50%,
_N2 : 3.0-5.0%, Ar: 1.0-5.0%
Gas group B: AlCl ₃ : 0.60 to 1.00%,
MeCl _x (chloride of Me): 0.10-0.20%
C ₂ H ₄ : 0.00 to 1.50%, N ₂ : 0.0 to 12.0%,
HCl: 0.00 to 0.10%, H ₂ :Remaining MeCl _x may satisfy the above percentage for each Me component.
Reaction atmosphere pressure: 4.5-5.0kPa
Reaction atmosphere temperature: 750-900℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Supply phase difference between gas group A and gas group B: 0.10 to 0.20 seconds

(2) Reactive gas for β layer formation Gas group A: NH ₃ : 2.0-3.0%, H ₂ : 30-40%, N ₂ : 6.0-10.0%
Gas group B: AlCl ₃ : 0.60 to 1.00%, TiCl ₄ : 0.07 to 0.40%,
C ₂ H ₄ : 0.00 to 1.50%, N ₂ : 0.0 to 12.0%, H ₂ : remainder Reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-850℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Supply phase difference between gas group A and gas group B: 0.10 to 0.20 seconds

(3) Reactive gas for forming δ layer Gas group A: NH ₃ : 2.8 to 7.4%, N ₂ : 3.6 to 8.5%,
Ar: 0.0~2.4%, _H2 : 33~48%
Gas group B: AlCl ₃ : 0.60 to 0.74%, TiCl ₄ : 0.10 to 0.32%,
C ₂ H ₄ : 0.00 to 1.50%, N ₂ : 0.0 to 12.0%, H ₂ : remainder Reaction atmosphere pressure: 4.6 to 5.0 kPa
Reaction atmosphere temperature: 740-875℃
Supply cycle: 2.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.22 seconds Supply phase difference between gas group A and gas group B: 0.10 to 0.15 seconds Gas The composition is changed linearly (gradient) during the δ layer deposition period, or in a stepwise manner between the first half and the second half of the deposition period.

Next, examples will be described.
Here, as a specific example of the coated tool of the present invention, a tool applied to an insert cutting tool using WC-based cemented carbide as the tool base will be described. The same applies when used in a drill or an end mill.

WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, and Co powder, all of which have an average particle size of 1 to 3 μm, were prepared as raw material powders, and these raw material powders were The composition shown in Table 1 was blended, further wax was added, and the mixture was ball-milled in acetone for 24 hours. After drying under reduced pressure, it was press-molded into a powder compact of a predetermined shape at a pressure of 98 MPa. A tool base made of WC-based cemented carbide that is vacuum sintered in a vacuum of 5 Pa and maintained at a predetermined temperature within the range of 1370 to 1470°C for 1 hour, and after sintering, has an insert shape of ISO standard SEEN1203AFSN. Tool bases A to C and tool bases D to F made of WC-based cemented carbide and having an insert shape of ISO standard CNMG120408 were manufactured, respectively.

Next, each layer was formed by CVD on the surfaces of these tool bases A to F using a CVD apparatus to obtain coated tools 1 to 10 of the present invention shown in Tables 7 and 8.
The film forming conditions are as described in Tables 2 and 3, and are generally as follows. The percentage of gas composition is volume percentage (the sum of gas group A and gas group B is the total).

(1) Reactive gas for α layer formation Gas group A: NH ₃ : 4.0 to 10.0%, H ₂ : 40 to 50%, N ₂ : 3.0 to 5.0%,
Ar: 1.0-5.0%
Gas group B: AlCl ₃ : 0.60 to 1.00%,
MeCl _x (chloride of Me): 0.10-0.20%
C ₂ H ₄ : 0.00 to 1.50%, N ₂ : 0.0 to 12.0%,
HCl: 0.00 to 0.10%, H ₂ :Remaining MeCl _x may satisfy the above percentage for each Me component.
Reaction atmosphere pressure: 4.5-5.0kPa
Reaction atmosphere temperature: 750-900℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Supply phase difference between gas group A and gas group B: 0.10 to 0.20 seconds

(2) Reactive gas for β layer formation Gas group A: NH ₃ : 2.0-3.0%, H ₂ : 30-40%, N ₂ : 6.0-10.0%
Gas group B: AlCl ₃ : 0.60 to 1.00%, TiCl ₄ : 0.07 to 0.40%,
C ₂ H ₄ : 0.00 to 1.50%, N ₂ : 0.0 to 12.0%, H ₂ : remainder Reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-850℃
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Supply phase difference between gas group A and gas group B: 0.10 to 0.20 seconds

(3) Reactive gas for forming δ layer Gas group A: NH ₃ : 2.8 to 7.4%, N ₂ : 3.6 to 8.5%,
Ar: 0.0~2.4%, _H2 : 33~48%
Gas group B: AlCl ₃ : 0.60 to 0.74%, TiCl ₄ : 0.10 to 0.32%,
C ₂ H ₄ : 0.00 to 1.50%, N ₂ : 0.0 to 12.0%, H ₂ : remainder Reaction atmosphere pressure: 4.6 to 5.0 kPa
Reaction atmosphere temperature: 740-875℃
Supply cycle: 2.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.22 seconds Supply phase difference between gas group A and gas group B: 0.10 to 0.15 seconds Gas The composition is changed linearly (gradiently) during the δ layer deposition period or in a stepwise manner between the first half and the second half of the deposition period.

Further, in coated tools 6, 7, 9, and 11 of the present invention, the δ layer shown in Table 8 was formed under the film forming conditions shown in Table 6.
For coated tools 1 to 6 of the present invention, the base layer and upper layer shown in Table 5 were formed under the film forming conditions shown in Table 4.

For comparison purposes, comparative coated tools 1 to 10 shown in Table 7 were manufactured by forming films on the surfaces of tool bases A to C using a CVD apparatus under the conditions shown in Tables 2 and 3. Further, in Comparative coated tools 5 and 7, the δ layer shown in Table 8 was formed under the film forming conditions shown in Table 6.
For comparison coated tools 1 to 6, the base layer and upper layer shown in Table 5 were formed under the film forming conditions shown in Table 4.

Coated tools 1 to 20 of the present invention and comparative coated tools 1 to 10 were tested by the method described above to determine the composition of each layer, the average layer thickness, the area ratio of crystal grains with a cubic structure and a hexagonal structure, and the face-centered cubic structure of the NaCl type. The area ratio of crystal grains was determined, and the results are shown in Tables 7 and 8.

Next, regarding the coated tools 1 to 20 of the present invention and comparative coated tools 1 to 10, the following cutting test 1 (coated tools 1 to 10 of the present invention, comparative coated tools 1 to 10) and cutting test 2 (coated tools of the present invention) were conducted. 11 to 20 and comparative coated tools 1 to 10), and the results are shown in Tables 9 and 10, respectively.

1. Cutting test 1: Dry high speed face milling, center cut cutting Cutter diameter: 125mm
Work material: JIS FCD800 width 100mm, length 400mm block material Rotation speed: 764rev/min
Cutting speed: 300m/min
Cut: 2.0mm
Single blade feed amount: 0.1mm/rev
Cutting time: 8 minutes (normal cutting speed is 200m/min)

2. Cutting test 2: Dry high-speed interrupted cutting Work material: JIS FCD800 Round bar with 8 vertical grooves equally spaced in the length direction Cutting speed: 300 m/min
Cut: 2.0mm
Feed: 0.1mm/rev
Cutting time: 5 minutes (normal cutting speed is 200m/min)

From the results shown in Tables 9 and 10, coated tools 1 to 20 of the present invention all have hard coating layers with excellent chipping resistance, so they are suitable for high-speed interrupted cutting of cast iron, etc. No thermal cracking or chipping occurs, and it exhibits excellent wear resistance over a long period of time. On the other hand, Comparative coated tools 1 to 10, which do not satisfy at least one of the requirements specified for coated tools of the present invention, cause chipping when used for high-speed interrupted cutting of cast iron, etc. It has reached the end of its useful life.

As mentioned above, the coated tool of the present invention can be used as a coated tool for high-speed interrupted cutting of materials other than cast iron, and also exhibits excellent wear resistance over a long period of time, so it can improve the high performance of cutting equipment. It is possible to fully satisfy the demands for reduction in labor and energy consumption of cutting processes, as well as cost reductions.

Claims (11)

A surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
A surface-coated cutting tool characterized in that xα and xβ satisfy |xβ−xα|≦0.04. The α layer contains a trace amount of Cl, and the content ratio zα of Cl in the total amount of C, N, and Cl (where zα is the atomic ratio) satisfies 0.0015≦zα≦0.0100. The surface-coated cutting tool according to claim 1 . The β layer contains a trace amount of Cl, and the content ratio zβ of Cl in the total amount of C, N, and Cl (where zβ is an atomic ratio) satisfies 0.0001≦zβ≦0.0020. The surface-coated cutting tool according to claim 1 or 2 . Claim 1 characterized in that the rake face of the surface-coated cutting tool has the hard coating layer including the laminated structure of the α layer and the β layer, and the flank face has the hard coating layer including the β layer. 4. The surface-coated cutting tool according to any one of 3 to 3 . A surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
The α layer contains a trace amount of Cl, and the content ratio zα of Cl in the total amount of C, N, and Cl (where zα is the atomic ratio) satisfies 0.0015≦zα≦0.0100. surface-coated cutting tools. A surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
The β layer contains a trace amount of Cl, and the content ratio zβ of Cl in the total amount of C, N, and Cl (where zβ is an atomic ratio) satisfies 0.0001≦zβ≦0.0020. surface-coated cutting tools. A surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base,
(a) the hard coating layer has an average layer thickness of 1.5 to 25.0 μm;
Al and Me, which mainly contain a hexagonal crystal structure with an average layer thickness of 0.5 to 5.0 μm (where Me is one or more elements selected from Si, Zr, V, Cr, Nb, Hf, and Mn) ) an α layer containing a composite nitride layer or a composite carbonitride layer,
A β layer containing a composite nitride layer or a composite carbonitride layer of Al and Ti mainly containing a cubic crystal structure with an average layer thickness of 1.0 to 20.0 μm,
A structure having at least one layer stacked with the α layer on the tool surface side and the β layer on the tool base side,
(b) The α layer has a composition of
Composition formula: (Al _xα Me _{1 -xα} ) (C _yα N _{1 - yα} )
When expressed by satisfies 0.70≦xα≦0.95 and 0.0000≦yα≦0.0150,
(c) The composition of the β layer is
Compositional formula: (Al _xβ Ti _{1 -xβ} ) (C _yβ N _1-yβ )
When expressed by satisfies 0.65≦xβ≦0.95 and 0.0000≦yβ≦0.0150,
(d) The α layer has a nanoindentation indentation hardness Hα of 15 GPa≦Hα≦28 GPa,
(e) The β layer has a nanoindentation indentation hardness Hβ of 30GPa≦Hβ≦45GPa,
A surface-coated cutting tool characterized in that the rake face of the surface-coated cutting tool has the hard coating layer including the laminated structure of the α layer and the β layer, and the flank face has the hard coating layer including the β layer. tool. The β layer contains a trace amount of Cl, and the content ratio zβ of Cl in the total amount of C, N, and Cl (where zβ is an atomic ratio) satisfies 0.0001≦zβ≦0.0020. The surface-coated cutting tool according to claim 5 . Claim 5 characterized in that the rake face of the surface-coated cutting tool has the hard coating layer including the laminated structure of the α layer and the β layer, and the flank face has the hard coating layer including the β layer. The surface-coated cutting tool according to any one of , 6 and 8 . A composite nitride or composite carbonitride of Al and Ti that mainly contains a cubic structure between the α layer and the β layer, when the xα and the xβ are |xβ−xα|>0.04. There is an AlTiCN layer δ containing at least crystal grains of
(a) The AlTiCNδ layer has a region divided into two equal parts in the layer thickness direction.
When the composition of the region on the tool base side is expressed by the composition formula: (Al _xδL Ti _(1-xδL) ) (C _yδL N _(1-yδL) ), the average content ratio of Al to the total amount of Ti and Al xδL and the average content ratio yδL of C in the total amount of C and N (however, xδL and yδL are both atomic ratios),
Further, when the composition of the region on the tool surface side of the region bisected in the layer thickness direction is expressed by the composition formula: (Al _xδH Ti _(1-xδH) ) (C _yδH N _(1-yδH) ), The average content ratio xδH of Al in the total amount of Ti and Al, and the average content ratio yδH of C in the total amount of C and N (however, xδH and yδH are both atomic ratios),
xα≦xδH<xδL<xβ or xβ<xδL<xδH≦xα, and
satisfies 0.0000≦yδH≦0.0150 and 0.0000≦yδL≦0.0150,
(b) The TiAlCN layer δ satisfies 0.1 μm≦Lδ≦1.0 μm, where Lδ is the average layer thickness.
The surface-coated cutting tool according to any one of claims 5 to 9, characterized in that: When analyzed from a longitudinal section perpendicular to the surface of the tool base, the α layer contains 70 area % or more and 95 area % or less of crystal grains having a hexagonal crystal structure,
The β layer contains 90 area % or more of crystal grains having a cubic crystal structure when analyzed from a longitudinal section perpendicular to the surface of the tool base.
The surface-coated cutting tool according to any one of claims 1 to 10 .