JP2011194518A - Surface-coated cutting tool for milling work superior in wear resistance and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool having a hard coating layer exhibiting superior chipping resistance and wear resistance in high speed and high-feed milling cutting, and to provide a method of manufacturing the surface-coated cutting tool.SOLUTION: In the surface-coated cutting tool, a Ti compound layer or a (Ti, Al)N layer is formed on a tool base body surface as a lower layer. On the lower layer, an adhesion layer composed of YSZ with (001) plane orientation, an intermediate layer having a crystal structure being a corundum structure and composed of (Cr, Al)Oor CrOwith (0001) plane orientation, and an upper layer having a crystal structure being the corundum structure and composed of α-AlOwith (0001) plane orientation formed by a MOCVD method are formed by a Dynamic Aurora PLD method, respectively.

Description

  The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance with a hard coating layer in high-speed and high-feed milling processing of steel, cast iron, and the like, and a method for manufacturing the same.

  In conventional coated tools, the hard coating layer is usually formed by PVD methods such as CVD, arc ion plating, magnetron sputtering, unbalanced magnetron sputtering, etc. A film forming method has attracted attention.

As a coated tool using the PLD method, a substrate made of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet (hereinafter collectively referred to as a tool substrate) On the surface of the
(A) Titanium carbide (hereinafter referred to as TiC) layer, nitride (hereinafter referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, titanium and aluminum formed by chemical vapor deposition or physical vapor deposition A lower layer made of a titanium compound layer made of one or more of the composite nitride (hereinafter referred to as (TiAl) N) layers and having an overall average layer thickness of 0.3 to 3 μm is formed. And
(B) The lower layer surface is formed by a so-called PLD method (Pulsed Laser Deposition) in which a target made of yttrium-stabilized zirconia (hereinafter referred to as YSZ) is irradiated with a magnetic field (001). ) Having a plane orientation and forming an adhesion layer composed of a yttrium-stabilized zirconia (hereinafter referred to as YSZ) layer having a layer thickness of 0.02 to 0.2 μm;
(C) Using a target made of chromium oxide or a mixture of chromium oxide and α-alumina on the adhesion layer, a layer thickness of 0.02 to 0.2 μm is obtained in the same manner as in the above (b). Chromium and aluminum oxide having (0001) plane orientation and a chromium content (Cr / (Cr + Al)) in the total amount with aluminum of 0.2 to 1 (however, atomic ratio) Forming a solid solution [hereinafter referred to as (Cr, Al) ₂ O ₃ ] layer, or an intermediate layer made of a chromium oxide layer;
(D) The content ratio of chromium in the total amount with aluminum in the same manner as in (c) above, using a target made of α-alumina or a mixture of chromium oxide and α-alumina on the intermediate layer. A chromium-aluminum oxide solid solution [hereinafter referred to as (Cr, Al) ₂ O ₃ ] layer having a hexagonal crystal structure in which (Cr / (Cr + Al)) is 0.15 or less (however, atomic ratio); Or the coating tool formed by forming the hard coating layer comprised by forming the upper layer which consists of (alpha)-alumina layers is known (refer patent document 1 hereafter).

  FIG. 1 shows an outline of an apparatus used in the above-described PLD method. According to this PLD method, a target is irradiated with an excimer laser, and a magnetic field is applied and adjusted by an electromagnet disposed between the target and the substrate. Then, plumes (electrons, ions, neutral atoms and molecules, aggregates of polyatomic molecules, clusters, etc.) involved in film formation can be used while maintaining a high electron temperature and kinetic energy. It is known that a variety of targets can be used in addition to control of the crystal structure and characteristics of the film, and there is little deviation between the target and the film composition, and contamination can be reduced.

For example, using the apparatus shown in FIG. 1 after forming the lower layer made of the Ti compound layer by chemical vapor deposition or physical vapor deposition,
Target: Yttrium stabilized zirconia (YSZ)
Oxygen partial pressure in vacuum: 1 × 10 ^{−2 to} 10 Pa
Tool substrate temperature: 500-850 ° C.
Magnetic field strength: An adhesion layer is formed under a condition of 2000 Ga or less,
Then, using the same device as above on the adhesion layer,
Target: Cr ₂ O ₃ or a mixture of Cr ₂ O ₃ and α-Al ₂ O ₃ Oxygen partial pressure in vacuum: 1 × 10 ^{−2 to} 10 Pa
Tool substrate temperature: 500-850 ° C.
Magnetic field strength: An intermediate layer is formed under the condition of 2000 Ga or less,
Then, using the same device as above on the intermediate layer,
Target: α-Al ₂ O ₃ or a mixture of Cr ₂ O ₃ and α-Al ₂ O ₃ Oxygen partial pressure in vacuum: 1 × 10 ^{−2 to} 10 Pa
Tool substrate temperature: 500-850 ° C.
Magnetic field strength: It is known to be produced by forming an upper layer under the condition of 2000 Ga or less.

JP 2009-72838 A

  In recent years, the performance of cutting equipment has been remarkable, while on the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and with this, cutting tends to be performed under severer conditions. In the above-mentioned conventional coated tool, there is no problem when it is used for cutting under normal conditions such as steel and cast iron, but especially when this is used for high-speed high-feed milling with severe cutting conditions. If the interlayer adhesion strength of the hard coating layer is inadequate, defects or delamination may occur, and if the wear resistance of the hard coating layer is insufficient, wear damage will increase. Even in this case, there was a problem that the service life was reached in a relatively short time.

In the method of forming the (Cr, Al) ₂ O ₃ layer or α-alumina layer having the same orientation as the intermediate layer in the upper layer using the PLD method described above, the crystal orientation degree of the upper layer is not good. Therefore, it has been desired to improve the peeling resistance and the wear resistance by further improving the degree of crystal orientation. Furthermore, although the PLD method is suitable for surface treatment of a fine area, it is not suitable for uniformly coating a large-area tool base or a tool base having a complicated shape.

  Therefore, the technical problem to be solved by the present invention, that is, the object of the present invention is to exhibit excellent chipping resistance and peeling resistance even when used for high-speed high-feed milling with severe cutting conditions. It is another object of the present invention to provide a surface-coated cutting tool that realizes excellent wear resistance, and that can be applied to a tool substrate having a large area and a complicated shape, and a manufacturing method thereof.

In view of the above, the present inventors have conducted intensive research to increase the adhesion strength between the layers constituting the hard coating layer and to improve the wear resistance of the hard coating layer. The following knowledge was acquired about the layer structure of a layer, and the formation method of a hard coating layer.
(A) For example, in a layer structure of a hard coating layer of a conventional coated tool, a Ti compound layer such as a TiC layer formed by chemical vapor deposition, a TiN layer, a TiCN layer, or a (Ti, Al) N layer formed by physical vapor deposition By forming a (Cr, Al) ₂ O ₃ layer on the upper surface of the substrate, and further forming an Al ₂ O ₃ layer thereon, the high temperature hardness and heat resistance of the Al ₂ O ₃ layer are utilized to make it hard Although it is conceivable to improve the wear resistance of the coating layer, the hard coating layer having such a layer structure has an inadequate interlayer adhesion strength, and therefore, delamination, chipping and chipping cannot be avoided.

(B) However, when a hard coating layer is formed by the PLD method, the interlayer adhesion strength of each layer formed can be improved, and the crystallinity and crystal structure of each layer constituting the hard coating layer can be improved. By controlling, it is possible to improve the high-temperature strength of the hard coating layer as a whole, and it is possible to form a crystal structure and a crystalline layer suitable for cutting conditions, so that the chipping resistance and the wear resistance are improved. Can also be planned.
That is, according to the PLD method, for example, in a vacuum atmosphere in which the temperature of the tool base is maintained at 500 to 850 ° C. and the oxygen partial pressure is set to 1 × 10 ^{−2 to} 10 Pa, a magnetic field of 2000 Ga or less is applied. By irradiating the target with a laser, preferably an excimer laser, a hard coating layer having desired characteristics can be formed.

(C) In the case of the coated tool of the present invention, first, a lower layer made of a Ti compound is formed on the surface of the tool base in a reactor by chemical vapor deposition (hereinafter referred to as CVD) and / or physical vapor deposition (hereinafter referred to as PVD). Form.
Next, the target is a sintered body of yttrium-stabilized zirconia (hereinafter referred to as YSZ), and the YSZ target is irradiated with a laser under the conditions of the temperature condition, atmospheric condition, and magnetic field condition of (b), An adhesion layer made of a YSZ layer having (001) plane orientation is formed on the lower layer formed by the CVD method and / or the PVD method.
Next, a target made of chromium oxide (hereinafter referred to as Cr ₂ O ₃ ), or Cr ₂ O ₃ and α-alumina, under the same conditions of temperature, atmosphere, and magnetic field as in (b) above. A target made of a mixture (hereinafter referred to as α-Al ₂ O ₃ ) is irradiated with laser, and a Cr ₂ O ₃ layer having a (0001) plane orientation with a crystal structure of a corundum structure or (Cr, Al) _An intermediate layer composed of ₂ O ₃ layers is formed.
The laser to be used is preferably an excimer laser in that the wavelength is short and a part of the target can be sputtered as accurately as necessary.
(D) Thereafter, the temperature of the tool substrate is maintained at 850 to 1050 ° C. using metal organic chemical vapor deposition (hereinafter referred to as MOCVD method), and argon (Ar ) And / or hydrogen (H ₂ ) as a carrier gas to supply trimethylaluminum (Al (CH ₃ ) ₃ ) and oxygen (O ₂ ) and / or carbon dioxide (CO ₂ ), so that the crystal structure is changed from the corundum structure. An upper layer made of an α-Al ₂ O ₃ layer having a (0001) plane orientation is formed.
As described above, after forming the lower layer on the substrate by the normal CVD method and PVD method, after forming the adhesion layer and intermediate layer having a predetermined plane orientation by the PLD method, the upper layer is formed by the MOCVD method. By forming, a hard coating layer with an improved degree of orientation of the upper layer can be formed.

(E) In the film formation by the PLD method of (c), an adhesion layer made of YSZ having (001) plane orientation and Cr ₂ O ₃ having (0001) plane orientation between the lower layer and the upper layer. Layer or an intermediate layer composed of (Cr, Al) ₂ O ₃ layer improves adhesion strength between the layers and also increases the degree of plane orientation of the upper layer. Strength and wear resistance are greatly improved.

(F) In addition, in forming the intermediate layer composed of the Cr ₂ O ₃ layer or the (Cr, Al) ₂ O ₃ layer by the PLD method of (c), a mixture of α-Al ₂ O ₃ and Cr ₂ O ₃ Al contained in the intermediate layer by adjusting film formation conditions such as the mixing ratio of α-Al ₂ O ₃ and Cr ₂ O ₃ of the body target, laser irradiation conditions (irradiation amount, irradiation time), applied magnetic field conditions, etc. Content ratio of Cr and Cr and the degree of orientation of the intermediate layer can be changed. As a result, the degree of orientation of the α-Al ₂ O ₃ layer formed by the MOCVD method as the upper layer can be controlled. The upper layer can be provided with a predetermined excellent chipping resistance and wear resistance.
For example, when the film forming conditions are adjusted so that the Cr content ratio (Cr / (Al + Cr)) in the intermediate layer is 0.2 to 1, the upper layer has α-Al ₂ O having (0001) plane orientation. _Three layers are preferentially formed.
In addition, since the Cr content ratio (Cr / (Al + Cr)) = 1 in the intermediate layer means that the intermediate layer is composed of a Cr ₂ O ₃ layer, in this case, the laser to the Cr ₂ O ₃ target It means that irradiation is performed.
The intermediate layer does not need to be formed as a single layer. For example, even if the intermediate layer is formed as a multilayer structure of a Cr ₂ O ₃ layer and a (Cr, Al) ₂ O ₃ layer, the object of the present invention is achieved. There is no loss.

(G) In the above (c) and (e), a YSZ layer having (001) orientation was formed as an adhesion layer, but the YSZ layer itself does not have (001) orientation and has a predetermined high-temperature strength. In addition, even if the YSZ layer does not have (001) orientation, a certain degree of (0001) plane orientation can be obtained in the intermediate layer and the upper layer. When strength and wear resistance are not required, for example, when cutting under severe conditions is not performed, the YSZ layer does not have (001) orientation and is hard-coated. Since the entire layer has a certain degree of interlayer adhesion strength and wear resistance, instead of the YSZ layer having (001) plane orientation, a YSZ layer having no (001) plane orientation is used as the adhesion layer. It is also possible to provide it.

This invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
The hard coating layer is
(A) As a lower layer, one of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, and a composite nitride layer of titanium and aluminum having a total layer thickness of 0.3 to 5 μm or A titanium compound layer composed of two or more layers,
(B) as an adhesion layer, an yttrium-stabilized zirconia layer having a layer thickness of 0.02 to 0.2 μm,
(C) The intermediate layer has a total layer thickness of 0.02 to 0.5 μm, and the crystal structure is a corundum structure, has (0001) plane orientation, and occupies the total amount with aluminum. An oxide solid solution layer of chromium and aluminum having a chromium content (Cr / (Cr + Al)) of 0.2 to 1 (however, atomic ratio), or an oxide layer of chromium,
(D) As an upper layer, the layer has a thickness of 0.3 to 3.0 μm, and the crystal structure is a corundum structure, has (0001) plane orientation, and is formed by MOCVD. Alumina layer,
A surface-coated cutting tool comprising the lower layer, the adhesion layer, the intermediate layer, and the upper layer of (a) to (d).
(2) The surface-coated cutting tool according to (1), wherein the adhesion layer is an yttrium-stabilized zirconia layer having (001) plane orientation.
(3) Method for producing a surface-coated cutting tool in which a hard coating layer comprising a lower layer, an adhesion layer, an intermediate layer, and an upper layer is formed on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet In the hard coating layer,
(A) From one or more of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, and a titanium and aluminum composite nitride layer by chemical vapor deposition or physical vapor deposition in a reactor. Forming a lower layer by depositing a titanium compound layer to be a total layer thickness of 0.3 to 5 μm;
(B) Next, a laser is applied to a target made of yttrium-stabilized zirconia in a vacuum atmosphere in which the temperature of the tool base is maintained at 500 to 850 ° C. and the oxygen partial pressure in the atmosphere is 1 × 10 ^{−2 to} 10 Pa. Irradiating to form an adhesion layer made of an yttrium-stabilized zirconia layer having a thickness of 0.02 to 0.2 μm on the surface of the lower layer;
(C) Next, a target composed of chromium oxide or a mixture of chromium oxide and α-alumina is irradiated with a laser under the same conditions as in (b) above, and 0.02 to 0.0. The crystal structure with a layer thickness of 5 μm consists of a corundum structure, has (0001) plane orientation, and the chromium content (Cr / (Cr + Al)) in the total amount with aluminum is 0.2 to 1 (however, A step of forming an intermediate layer composed of an oxide solid solution layer of chromium and aluminum having an atomic ratio) or an oxide layer of chromium;
(D) then, while maintaining the temperature of the tool substrate to from 850 to 1050 ° C., to maintain the pressure in the reactor to 50～10,000Pa, argon (Ar) and / or hydrogen _{(H 2)} carrier gas By supplying trimethylaluminum (Al (CH ₃ ) ₃ ) and oxygen (O ₂ ) and / or carbon dioxide (CO ₂ ) as the intermediate layer surface having a layer thickness of 0.3 to 3.0 μm. And a step of forming an upper layer made of an α-alumina layer having a corundum crystal structure by an MOCVD method.
(4) The method for manufacturing a surface-coated cutting tool according to (3), wherein the heating of the tool base in the step (d) is a heating by a cold wall method. "
It has the characteristics.

  Below, the hard coating layer of the coated tool of this invention and the manufacturing method of a coated tool are demonstrated in detail.

(1) Lower layer (Ti compound layer)
The lower layer made of the Ti compound layer formed by the ordinary CVD method, PVD method, etc. allows the hard coating layer to maintain the high temperature strength by its excellent high temperature strength, as well as both the tool base and the YSZ layer. It has an effect of firmly adhering, and thus contributing to an improvement in the adhesion of the hard coating layer to the tool substrate. However, when the total average layer thickness is less than 0.3 μm, the above-mentioned effect cannot be exhibited sufficiently, When the total layer thickness exceeds 5 μm, thermal fatigue is likely to occur particularly in high-speed cutting such as high-speed milling with high heat generation, and this causes thermal cracks. It was set to 5 μm.

(2) Adhesion layer (YSZ layer)
The yttrium-stabilized zirconia (YSZ) layer having (001) plane orientation constituting the adhesion layer is maintained at a temperature of 500 to 850 ° C. in the atmosphere of the tool base provided with the lower layer by the PLD method. It can be formed by irradiating the target with a laser in a vacuum atmosphere with an oxygen partial pressure of 1 × 10 ^{−2 to} 10 Pa and applying a magnetic field of 2000 Ga or less, but both the lower layer and the intermediate layer are strong. In order to improve the high temperature strength of the hard coating layer with adhesion, chipping is prevented from occurring in the hard coating layer in high-speed cutting.
In addition, since the YSZ layer has (001) plane orientation, the (0001) plane orientation degree of the intermediate layer formed thereon is increased, and as a result, the (0001) plane orientation of the upper layer is increased. Therefore, the wear resistance of the hard coating layer is further improved in high-speed cutting under severe conditions such as high-speed milling.
However, if the layer thickness of the YSZ layer is less than 0.02 μm, the effect of improving the interlayer bonding strength is small, and if the layer thickness exceeds 0.2 μm, the YSZ crystal tends to grow, and as a result, the YSZ layer Since the strength decreases, the thickness of the YSZ layer as the adhesion layer is determined to be 0.02 to 0.2 μm.
As already described, even when the YSZ layer does not have (001) plane orientation, the hard coating layer has predetermined chipping resistance and wear resistance, so that it is as chipping resistant as high-speed milling. It is also possible to provide a YSZ layer having no (001) plane orientation as an adhesion layer under mild cutting conditions that do not require wear resistance.

(3) Intermediate layer When an intermediate layer is formed on the YSZ layer by the PLD method, an intermediate layer corresponding to the type of target used for film formation is formed, but the chromium content in the total amount with aluminum ( When (Cr, Al) ₂ O ₃ layer having Cr / (Cr + Al)) of 0.2 to 1 (however, atomic ratio) was formed as an intermediate layer, or Cr ₂ O ₃ layer was formed as an intermediate layer In each case, an intermediate layer having (0001) plane orientation is formed, and the intermediate layer has (0001) plane orientation so that (0001) of the upper layer formed thereon is formed. The degree of surface orientation is further increased, and excellent wear resistance is provided.
As the target for forming the intermediate layer, it is possible to use a mixture of _Cr 2 _{O 3} or _Cr 2 _{O 3} and _α-Al 2 _{O 3,} for example, _Cr 2 _{O 3} and _α-Al 2 _{O 3} The target of the tool base provided with the vapor deposition layer is maintained at 500 to 850 ° C., and the oxygen partial pressure in the atmosphere is 1 × 10 ^{−2 to} 10 Pa in a vacuum atmosphere. Is irradiated with a laser, and a film is formed in a state where a magnetic field of 2000 Ga or less is applied, so that it has (0001) plane orientation and the content ratio of chromium in the total amount with aluminum (Cr / (Cr + Al) ) Is 0.2 or more (however, the atomic ratio), and a (Cr, Al) ₂ O ₃ layer can be formed as an intermediate layer.
When this (Cr, Al) ₂ O ₃ layer is provided as an intermediate layer, when the α-Al ₂ O ₃ layer is formed as the upper layer by MOCVD, the (0001) plane is oriented with a high degree of orientation. The α-Al ₂ O ₃ layer is formed, and the upper layer exhibits excellent wear resistance even under severe cutting conditions such as high-speed high-feed milling.
In the intermediate layer forming target, the chromium content ratio (Cr / (Cr + Al)) is 1, that is, a Cr ₂ O ₃ target is used. Even when an oriented Cr ₂ O ₃ intermediate layer is formed and an upper layer is further formed thereon, the α-Al ₂ oriented in the (0001) plane is also formed on the Cr ₂ O ₃ intermediate layer. An upper layer composed of an O ₃ layer and excellent in wear resistance is formed.
If the thickness of the intermediate layer is less than 0.02 μm, the interlayer strength of each layer cannot be improved and the high-temperature strength of the hard coating layer as a whole cannot be improved, and the degree of orientation of the upper layer formed thereon can be increased. On the other hand, if the layer thickness exceeds 0.5 μm, the crystal grains in the intermediate layer easily grow, and as a result, the α-Al ₂ O ₃ layer in the upper layer also grows and is hard-coated. In order to easily cause chipping in the layer, the thickness of the intermediate layer was determined to be 0.02 to 0.5 μm.

(4) Upper layer The temperature of the tool base provided with the intermediate layer is maintained at 850 to 1050 ° C., the pressure in the reactor is maintained at 50 to 10,000 Pa, and argon (Ar) and / or hydrogen (H ₂ ). And 0.1 to 5.0 and 1.0 to 60 in terms of volume% of trimethylaluminum (Al (CH ₃ ) ₃ ) and oxygen (O ₂ ) and / or carbon dioxide (CO ₂ ), respectively, as a carrier gas The tool base is introduced into the reactor, and the tool base is heated by a cold wall method, for example, by holding the metal stage holding the tool base by induction heating with a high frequency electric field of 0 to 230 V, 13.5 kHz, 0 to 20 A. As a result, an α-Al ₂ O ₃ layer oriented in the (0001) plane is formed.
The formation of the α-Al ₂ O ₃ layer is none other than the formation by the MOCVD method, but the reactive gas is heated only in the vicinity of the substrate by the cold wall method on the intermediate layer having (0001) plane orientation. Is formed, an α-Al ₂ O ₃ layer with a high degree of (0001) orientation is formed as the upper layer, and the upper layer made of this α-Al ₂ O ₃ layer Has excellent high temperature hardness.
In addition, the upper layer formed of the α-Al ₂ O ₃ layer having (0001) plane orientation formed by MOCVD is excellent in adhesion and adhesion strength with the intermediate layer. It has excellent high temperature strength.
Therefore, the coated tool of the present invention in which an α-Al ₂ O ₃ layer having (0001) plane orientation formed by MOCVD is deposited as an upper layer is accompanied by high heat generation and is called high-speed high-feed milling Even when used under severe cutting conditions, it exhibits excellent wear resistance as well as excellent chipping resistance, and tool characteristics are remarkably improved.
However, if the thickness of the upper layer is less than 0.3 μm, excellent tool characteristics cannot be fully exerted. On the other hand, if the layer thickness exceeds 3.0 μm, chipping and chipping are likely to occur at the cutting edge. Therefore, the layer thickness of the upper layer was determined to be 0.3 to 3.0 μm.

(5) Film forming conditions by PLD method and MOCVD method In the present invention, a TiC layer, a TiN layer, a TiCN layer, and (Ti, Al) are first formed on the surface of the tool base by the conventionally known CVD method and PVD method. After depositing a titanium compound layer consisting of one or more of the N layers to a total layer thickness of 0.3 to 5 μm to form a lower layer, an adhesion layer and an intermediate layer are formed by a PLD method. Form a film.
Compared with the conventional PLD method in which a magnetic field is generated using a permanent magnet, the PLD method can increase the substrate temperature, can freely control the strength of the magnetic field, and can further apply a magnetic field applied to the target or the substrate. The crystal structure and characteristics of film formation can be freely controlled by adjusting the thickness of the film, but the present invention takes advantage of these advantages of the PLD method and at the same time forms a film on a tool substrate (substrate). By specifying the type of layer, intermediate layer, and film formation conditions, and combining with the formation of the upper layer by MOCVD, the unique problems of chipping resistance and wear resistance required for hard coating layers of coated tools It is a solution.
That is, when forming the adhesion layer and the intermediate layer by irradiating the target with a laser in forming the adhesion layer and the intermediate layer by the PLD method, the temperature of the tool base is increased in order to increase the film formation rate and the crystal orientation. Must be maintained at 500 to 850 ° C., and in order to control the oxygen amount of each layer and oxide within an appropriate range, the atmospheric conditions are set to a vacuum atmosphere with an O ₂ partial pressure of 1 × 10 ^{−2 to} 10 Pa. Furthermore, in order to control the crystal orientation, crystal structure, and crystal grain growth of each layer, it is necessary to adjust the applied magnetic field within a range of 2000 G or less.
Further, in order to increase the deposition rate and crystal orientation in forming the upper layer by the MOCVD method, the temperature of the tool base is maintained at 850 to 1050 ° C., and the pressure in the reactor is set to 50 to 10,000 Pa. And trimethylaluminum (Al (CH ₃ ) ₃ ), oxygen (O ₂ ) and / or carbon dioxide (CO ₂ ) in a volume percentage of 0 using argon (Ar) and / or hydrogen (H ₂ ) as a carrier gas. Feed into the reactor under conditions of 1-5.0 and 1.0-60.
Then, after forming a lower layer on the tool base by a normal CVD method or PVD method, a YSZ layer having (001) plane orientation as an adhesion layer by the PLD method under the temperature condition, atmospheric condition and magnetic field condition Then, a target made of Cr ₂ O ₃ or a mixture of Cr ₂ O ₃ and α-Al ₂ O ₃ is irradiated with a laser, and the crystal structure has a corundum structure and (0001) plane orientation is improved. An intermediate layer made of (Cr, Al) ₂ O ₃ layer or Cr ₂ O ₃ layer is formed, and then α-Al ₂ O having a (0001) plane orientation with a crystal structure of a corundum structure by MOCVD. _An upper layer composed of _three layers is formed. Each layer thus formed has a strong adhesion strength, and also includes a target type, a laser irradiation condition, a magnetic field application condition, By adjusting the gas composition at the time of forming the upper layer by MOCVD method, the film composition, crystal structure and crystal orientation of each layer can be controlled. As a result, excellent chipping resistance and excellent wear resistance Can be formed.
Therefore, the coated tool manufactured by the method as described above exhibits excellent chipping resistance and excellent wear resistance over a long period of time even in cutting under severe conditions such as high-speed milling with high heat generation.

The coated tool of the present invention has a lower layer composed of a Ti compound layer as a layer constituting a hard coating layer, an adhesion layer composed of a YSZ layer having (001) plane orientation, and a (0001) plane oriented crystal structure composed of a corundum structure. (Cr, Al) ₂ O ₃ layer having a property, an intermediate layer comprising a Cr ₂ O ₃ layer, and an upper layer comprising an α-Al ₂ O ₃ layer having a (0001) plane orientation and a crystal structure comprising a corundum structure Formed, the adhesion strength between the layers is increased by such a layer structure, the hard coating layer has an excellent high temperature strength as a whole, and in particular, the upper layer has (0001) plane orientation by MOCVD. Since the upper layer is provided with excellent wear resistance by being composed of the enhanced α-Al ₂ O ₃ layer, the coated tool of the present invention is, for example, a high-speed high-feed mill such as steel or cast iron. In ring processing, it exhibits excellent chipping resistance and excellent wear resistance, exhibits excellent tool characteristics over a long period of time, and prolongs tool life.
The method for manufacturing a coated tool according to the present invention uses a PLD method for a tool substrate on which a predetermined lower layer is previously formed by a CVD method or a PVD method, and further, a target type, composition, and film formation. A desired adhesion layer and an intermediate layer can be formed by selecting conditions and the like, and a desired crystal structure is formed on the intermediate layer having the (0001) plane orientation thus formed by MOCVD. Since an upper layer having crystal orientation can be formed, a coated tool excellent in chipping resistance and wear resistance can be easily and reliably manufactured.

It is outline | summary explanatory drawing of the apparatus used for PLD method.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

As raw material powders, WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, and Co powder each having an average particle diameter of 1 to 3 μm are prepared. The raw material powder is blended in the blending composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge is subjected to a honing process of R: 0.06 mm. Thus, tool bases A to F made of a WC-based cemented carbide having an insert shape defined as SPMN120308 in the ISO standard were manufactured.

Further, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, blend these raw material powders into the composition shown in Table 2, wet mix with a ball mill for 24 hours, dry, and press-mold into a green compact at 98 MPa pressure The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.06 mm. Then, tool bases a to f made of TiCN-based cermet having an insert shape specified as SPMN120308 in the ISO standard were formed.

Next, each of the tool bases A to F and the tool bases a to f is charged into a normal chemical vapor deposition apparatus or arc ion plating apparatus,
(A) First, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in JP-A-6-8010, and the other conditions are ordinary granularity. The Ti compound layer having the target layer thickness shown in Tables 5 and 6 was vapor-deposited as the lower layer of the hard coating layer under the conditions shown in FIG.
Then, the tool base on which the lower layer is formed is charged into a PLD apparatus,
(B) First, the YSZ target is irradiated with an excimer laser under the film formation conditions shown in Table 4, and the (001) orientation of the target layer thickness shown in Tables 5 and 6 is formed on the lower layer of the tool base. Forming an adhesive layer (YSZ layer) having
(C) Next, excimer laser was irradiated to various targets under the same conditions as shown in Table 4, and the target layer thicknesses shown in Tables 5 and 6 and the (0001) plane were formed on the adhesion layer. Forming an intermediate layer ((Cr, Al) ₂ O ₃ layer, Cr ₂ O ₃ layer) having orientation;
(D) Thereafter, the target layer thicknesses shown in Tables 5 and 6 are formed on the intermediate layer having (0001) plane orientation by high-frequency induction heating for various gas compositions under the conditions shown in Table 4 In addition, the coated tools 1 to 16 of the present invention were manufactured by forming an upper layer (α-Al ₂ O ₃ layer) having (0001) plane orientation.

For comparison purposes, the adhesion layer, the intermediate layer, and the upper layer shown in JP-A-2009-72838 (same as Patent Document 1) were formed by the PLD method, and comparative coated tools 1 to 8 were produced.
That is, each of the tool bases A to F and the tool bases a to f is charged into a normal chemical vapor deposition apparatus or arc ion plating apparatus,
(A) First, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in JP-A-6-8010, and the other conditions are ordinary granularity. The Ti compound layer having the target layer thickness shown in Tables 7 and 8 was vapor-deposited as a lower layer of the hard coating layer under the conditions shown in FIG.
Then, the tool base on which the lower layer is formed is charged into a PLD apparatus,
(B) First, the YSZ target is irradiated with an excimer laser under the film formation conditions shown in Table 4, and the (001) orientation of the target layer thickness shown in Tables 7 and 8 is formed on the lower layer of the tool base. Forming an adhesive layer (YSZ layer) having
(C) Next, excimer laser was irradiated to various targets under the same conditions as shown in Table 4, and the target layer thicknesses shown in Tables 7 and 8 and (0001) planes were formed on the adhesion layers. Forming an intermediate layer ((Cr, Al) ₂ O ₃ layer, Cr ₂ O ₃ layer) having orientation;
(D) Thereafter, various targets are irradiated with excimer laser under the same conditions as shown in Table 4, and the target layer thicknesses shown in Tables 7 and 8 are formed on the intermediate layer having (0001) plane orientation. Comparative coating tools 1 to 16 were manufactured by forming an upper layer (α-Al ₂ O ₃ layer, (Cr, Al) ₂ O ₃ ) having (0001) plane orientation.

Next, for the inventive coated tools 1-16 and comparative coated tools 1-16, the constituent layers of these hard coating layers were observed using an Auger spectroscopic analyzer (observed longitudinal section of the layers). It was confirmed that they had substantially the same composition, and the thicknesses of the constituent layers of the hard coating layers of these coated tools were measured using a scanning electron microscope (same longitudinal section measurement). The average layer thickness (average value of 5-point measurement) substantially the same as the layer thickness was shown.
Moreover, about the adhesion layer, intermediate | middle layer, upper layer which comprises the hard coating layer of this invention coating tool 1-16, and the upper layer of the hard coating layer of the comparative coating tool 1-16, the crystal structure is identified by X-ray diffraction. At the same time, the degree of crystal orientation was evaluated.
The results are shown in Tables 5-8.

Here, the orientation of the adhesion layer YSZ was defined as the (001) orientation when the diffraction peak of the (002) plane was the strongest peak in the range of 2θ of 20 to 80 °.
The orientation of the Cr ₂ O ₃ , (Cr, Al) ₂ O ₃ , and Al ₂ O ₃ layers is (0001) orientation when the value of TC (006) calculated by the following formula is 2 or more. It was.
TC (hkl) = I (hkl) / I ₀ (hkl) × [1 / n × ΣI (hkl) / I ₀ (hkl)]
Measured value of diffraction intensity of I (hkl) = (hkl) plane I ₀ (hkl) = standard intensity of (hkl) plane by ASTM n = number of diffraction planes used for calculation (7)
Diffraction surfaces used: (012), (104), (110), (006), (113), (024), (116)

Next, high-speed high-feed milling with a single blade was performed on the present coated tools 1 to 16 and comparative coated tools 1 to 16 under the following cutting conditions A to C.
[Cutting conditions A]
Work material: Block material of JIS / SS400,
Cutting speed: 500 m / min,
Cutting depth: 1.5 mm,
Cutting width: 30 mm (center cut)
Single blade feed rate: 0.25 mm / tooth,
Cutting time: 10 minutes,
Dry high-speed cutting test of mild steel under normal conditions (normal cutting speed is 280 m / min).
[Cutting conditions B]
Work material: Block material of JIS / S45C,
Cutting speed: 480 m / min,
Cutting depth: 1.5 mm,
Cutting width: 2.0 mm (down cut)
Single blade feed rate: 0.22 mm / tooth,
Cutting time: 5 minutes,
Dry high-speed cutting test of carbon steel under the conditions (normal cutting speed is 200 m / min).
[Cutting conditions C]
Work material: JIS / FC300 block,
Cutting speed: 500 m / min,
Cutting depth: 2.0 mm,
Cutting width: 30 mm (center cut)
Single blade feed rate: 0.25 mm / tooth,
Cutting time: 10 minutes,
Wet high-speed cutting test of normal cast iron under the conditions (normal cutting speed is 250 m / min).
And the flank wear width of the cutting edge in each said cutting test was measured, and this measurement result was shown in Table 9.

From the results shown in Tables 5 to 9, all of the coated tools 1 to 16 of the present invention have an adhesion layer having (001) plane orientation and an intermediate having (0001) plane orientation between the lower layer and the upper layer. In addition, since the upper layer is formed of an α-Al ₂ O ₃ layer having high (0001) plane orientation, the adhesion strength between the hard coating layers is large, and the hard coating layer The high-temperature strength as a whole is also high, so that it shows excellent chipping resistance in high-speed high-feed milling, and the adhesion layer has (001) plane orientation. As a result, the intermediate layer and the upper layer are (0001) Since it has a crystal structure with a high degree of plane orientation, it exhibits excellent wear resistance even in high-speed high-feed milling.
Moreover, the manufacturing method of this invention coated tool 1-16 forms the lower layer of a hard coating layer by normal CVD method or PVD method, and then the adhesion layer of a hard coating layer and PLD method under predetermined conditions An intermediate layer is formed, and then the upper layer of the hard coating layer is formed by MOCVD under a predetermined condition. The type and composition of the target are selected, and a laser is applied to the target under the predetermined condition. Irradiation can form an upper layer with a further enhanced crystal orientation by MOCVD after forming an adhesion layer and an intermediate layer with a predetermined crystal structure with an enhanced crystal orientation. A coated tool having tool characteristics required under severe cutting conditions such as milling can be reliably produced by a simple method.

On the other hand, in the comparative coating tools 1 to 16 in which the upper layer of the hard coating layer is formed by the PLD method similarly to the adhesion layer and the intermediate layer, the (0001) plane of the (Al ₂ O ₃ layer) of the upper layer Since the degree of orientation is low, the adhesion strength between each layer of the hard coating layer is not sufficient, and the wear resistance of the entire hard coating layer is also insufficient, causing delamination, chipping and chipping during high-speed high-feed milling. As a result, the service life was reached in a relatively short time.

  As described above, the coated tool of the present invention and the manufacturing method thereof have excellent wear resistance without occurrence of chipping even under severe cutting conditions such as high-speed high-feed milling of various work materials such as steel and cast iron. Since it exhibits excellent cutting performance over a long period of time, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting work, and the cost reduction.

Claims (4)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
The hard coating layer is
(A) As a lower layer, one of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, and a composite nitride layer of titanium and aluminum having a total layer thickness of 0.3 to 5 μm or A titanium compound layer composed of two or more layers,
(B) as an adhesion layer, an yttrium-stabilized zirconia layer having a layer thickness of 0.02 to 0.2 μm,
(C) The intermediate layer has a total layer thickness of 0.02 to 0.5 μm, and the crystal structure is a corundum structure, has (0001) plane orientation, and occupies the total amount with aluminum. An oxide solid solution layer of chromium and aluminum having a chromium content (Cr / (Cr + Al)) of 0.2 to 1 (however, atomic ratio), or an oxide layer of chromium,
(D) As an upper layer, the layer has a thickness of 0.3 to 3.0 μm, and the crystal structure is a corundum structure, has (0001) plane orientation, and is formed by MOCVD. Alumina layer,
A surface-coated cutting tool comprising the lower layer, the adhesion layer, the intermediate layer, and the upper layer of (a) to (d).   The surface-coated cutting tool according to claim 1, wherein the adhesion layer is an yttrium-stabilized zirconia layer having (001) plane orientation. In the method of manufacturing a surface-coated cutting tool in which a hard coating layer composed of a lower layer, an adhesion layer, an intermediate layer, and an upper layer is formed on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet, Hard coating layer
(A) From one or more of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, and a titanium and aluminum composite nitride layer by chemical vapor deposition or physical vapor deposition in a reactor. Forming a lower layer by depositing a titanium compound layer to be a total layer thickness of 0.3 to 5 μm;
(B) Next, a laser is applied to a target made of yttrium-stabilized zirconia in a vacuum atmosphere in which the temperature of the tool base is maintained at 500 to 850 ° C. and the oxygen partial pressure in the atmosphere is 1 × 10 ^{−2 to} 10 Pa. Irradiating to form an adhesion layer made of an yttrium-stabilized zirconia layer having a thickness of 0.02 to 0.2 μm on the surface of the lower layer;
(C) Next, a target composed of chromium oxide or a mixture of chromium oxide and α-alumina is irradiated with a laser under the same conditions as in (b) above, and 0.05 to 0. The crystal structure is a corundum structure with a layer thickness of 5 μm, has (0001) plane orientation, and the chromium content (Cr / (Cr + Al)) in the total amount with aluminum is 0.2 to 1 (however, A step of forming an intermediate layer composed of an oxide solid solution layer of chromium and aluminum having an atomic ratio) or an oxide layer of chromium;
(D) then, while maintaining the temperature of the tool substrate to from 850 to 1050 ° C., to maintain the pressure in the reactor to 50～10,000Pa, argon (Ar) and / or hydrogen _{(H 2)} carrier gas By supplying trimethylaluminum (Al (CH ₃ ) ₃ ) and oxygen (O ₂ ) and / or carbon dioxide (CO ₂ ) as the intermediate layer surface having a layer thickness of 0.3 to 3.0 μm. And a step of forming an upper layer made of an α-alumina layer having a corundum crystal structure by an MOCVD method.   The method of manufacturing a surface-coated cutting tool according to claim 3, wherein the heating of the tool base in the step (d) is a heating by a cold wall method.

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