WO2014034923A1

WO2014034923A1 - Coated cutting tool

Info

Publication number: WO2014034923A1
Application number: PCT/JP2013/073475
Authority: WO
Inventors: 正和菊池; 翔太浅利
Original assignee: 株式会社タンガロイ
Priority date: 2012-08-31
Filing date: 2013-09-02
Publication date: 2014-03-06
Also published as: JP6264391B2; JPWO2014034923A1; JP2016155221A

Abstract

The purpose of the present invention is to provide a coated cutting tool with a long machining length and a long tool life and for which the area of removed coated layer is small even when machining under heavy machining conditions. The present invention is a coated cutting tool comprising a base material and a coating layer formed on a base material surface, and the coating layer comprises a top layer on the surface side and a bottom-most layer on the base material side. The bottom-most layer is configured as (Al_aTi_bM_c)N [provided that M represents at least one element selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, B, and Si; a represents the atomic ratio of elemental Al with respect to the total of elemental Al, elemental Ti, and elemental M; b represents the atomic ratio of elemental Ti with respect to the total of elemental Al, elemental Ti, and elemental M; c represents the atomic ratio of elemental M with respect to the total of elemental Al, elemental Ti, and elemental M; and a, b, and c satisfy 0.30≤a≤0.70, 0.30≤b≤0.70, 0≤c≤0.20, and a+b+c=1], and the mean particle diameter of the (Al_aTi_bM_c)N particle comprising the bottom-most layer is no more than 400 nm.

Description

Coated cutting tool

The present invention relates to a coated cutting tool.

Coated cutting tools in which a coating layer such as a TiN layer or TiAlN layer is coated on the surface of a substrate made of cemented carbide, cermet, cBN, etc. are excellent in mechanical strength and heat resistance, so steel, cast iron, stainless steel, heat resistance Used for cutting alloys.

As a prior art of the coated cutting tool, Ti and Al are formed on the surface of a substrate made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet through an adhesive physical vapor deposition coating layer made of titanium nitride having a specific thickness. There is a surface-covered cermet cutting tool formed by forming a wear-resistant physical vapor deposition coating layer made of a composite nitride and having a specific thickness (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 4-201002

In recent years, the efficiency of machining is remarkable, and cutting is performed at a higher cutting speed and greater cutting and feeding than before. Under such heavy cutting conditions where the tool edge temperature is high, the work material is likely to be welded to the surface of the coated cutting tool. In the prior art such as Patent Document 1, the chemical affinity between the base material and the coating layer is improved by coating TiN on the surface of the base material, and coating TiAlN on the surface, thereby increasing the adhesion strength between the base material and the coating layer. By improving, the peel resistance of the coating layer was improved. However, when an excessive load is applied to the interface between the substrate and the coating layer, there is a problem that the coating layer is largely peeled off, the working distance of the coated cutting tool is shortened, and the tool life is insufficient.

The present invention has been made to solve the above problems, and provides a coated cutting tool having a small peeling area of the coating layer, a long working distance and a long tool life even when cutting is performed under heavy cutting conditions. Objective.

The inventors have conducted research for the purpose of improving the peel resistance of the coating layer, and by optimizing the composition and particle size of the lowermost layer of the coating layer, the peeling area of the coating layer is minimized and the coating layer is coated. It has been found that the working distance of the cutting tool can be increased, and the present invention has been completed.

That is, the gist of the present invention is as follows.

(1) It consists of a substrate and a coating layer formed on the surface of the substrate. The coating layer is composed of an upper layer on the surface side and a lowermost layer on the substrate side, and the lowermost layer is (Al _a Ti _b _Mc ) N [Wherein M represents at least one element selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, B, and Si, and a represents Al element, Ti element, and M B represents the atomic ratio of Ti element to the sum of Al, Ti and M elements, and c represents the atom of M element to the sum of Al, Ti and M elements. The ratios a, b, and c satisfy 0.30 ≦ a ≦ 0.70, 0.30 ≦ b ≦ 0.70, 0 ≦ c ≦ 0.20, and a + b + c = 1. The coated cutting tool in which the average particle diameter of (Al _a Ti _b M _c ) N particles constituting the lowermost layer is 400 nm or less.

(2) a, b, and c satisfy the following conditions: 0.50 ≦ a ≦ 0.70, 0.30 ≦ b ≦ 0.50, 0 ≦ c ≦ 0.20, and a + b + c = 1 tool.

(3) The coated cutting tool according to (1) or (2), wherein the average particle diameter of (Al _a Ti _b M _c ) N particles constituting the lowermost layer is 10 to 400 nm.

(4) The coated cutting tool according to any one of (1) to (3), wherein the average layer thickness of the lowermost layer is 0.1 to 1 μm.

(5) The upper layer is made of at least one metal element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, Al, and Si; and at least of these metal elements (1) to (1) are monolayer or multilayer structures comprising at least one selected from the group consisting of one compound and at least one nonmetallic element selected from carbon, nitrogen, oxygen and boron. The coated cutting tool according to any one of 4).

(6) The coated cutting tool according to any one of (1) to (5), wherein the average layer thickness of the entire upper layer is 0.2 to 10 μm.

(7) Consists of a base material and a coating layer formed on the surface of the base material. The coating layer is composed of an upper layer on the surface side and a lowermost layer on the base material side, and the lowermost layer is (Al _d Cr _e L _f ) N. [However, L represents at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Y, B, and Si, and d represents an Al element, a Cr element, and L Represents the atomic ratio of the Al element to the sum of the elements, e represents the atomic ratio of the Cr element to the sum of the Al element, Cr element and L element, and f represents the atom of the L element relative to the sum of the Al element, Cr element and L element. D, e, and f satisfy the following conditions: 0.20 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.80, 0 ≦ f ≦ 0.20, and d + e + f = 1. A coated cutting tool in which the average particle diameter of (Al _d Cr _e L _f ) N particles constituting the lowermost layer is 400 nm or less.

(8) d, e, and f satisfy the following conditions: 0.40 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.60, 0 ≦ f ≦ 0.20, d + e + f = 1 Coated cutting tool.

(9) d, e, and f satisfy 0.40 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.60, 0 ≦ f ≦ 0.20, d ≧ e, and d + e + f = 1 (7 ) Or the coated cutting tool according to (8).

(10) either coated cutting tool constituting the lowermost layer average particle diameter of the _{_{_{(Al d Cr e L f)}}} N particles is 10 ~ 400nm (7) ~ ( 9).

(11) The coated cutting tool according to any one of (7) to (10), wherein the average layer thickness of the lowermost layer is 0.1 to 1 μm.

(12) The upper layer is a metal composed of at least one metal element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, Al, and Si; and at least of these metal elements A single-layer or multi-layer structure comprising at least one selected from the group consisting of one compound and at least one nonmetallic element selected from carbon, nitrogen, oxygen and boron (7) to (7) The coated cutting tool according to any one of 11).

(13) The coated cutting tool according to any one of (7) to (12), wherein an average layer thickness of the entire upper layer is 0.2 to 10 μm.

The coated cutting tool of the present invention has the effect that the coating layer is difficult to peel off even in cutting under heavy cutting conditions, and the machining distance is long and the tool life is long.

It is a conceptual diagram of the cross-sectional structure | tissue of the coated cutting tool with which the average particle diameter of the particle | grains which comprise the lowest layer is large. It is a conceptual diagram of the cross-sectional structure | tissue of the coating cutting tool with which the average particle diameter of the particle | grains which comprise the lowest layer is small.

The coated cutting tool of the present invention comprises a substrate and a coating layer formed on the surface of the substrate. The base material is not particularly limited as long as it is used as a base material for a coated cutting tool. For example, cemented carbide, cermet, ceramics, cubic boron nitride sintered body, diamond sintered body, high speed steel, etc. It can be used as the substrate. Among them, it is more preferable that the base material is a cemented carbide because the coated cutting tool of the present invention is excellent in wear resistance and fracture resistance.

The coating layer includes an upper layer on the surface side of the coated cutting tool and a lowermost layer on the substrate side. In one aspect of the present invention, the composition of the particles constituting the lowermost layer is (Al _a Ti _b M _c ) N [where M is Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y Represents at least one element selected from the group consisting of B, Si, a represents the atomic ratio of Al element to the sum of Al element, Ti element and M element, and b represents Al element, Ti element and M element Represents the atomic ratio of the Ti element to the sum of the elements, c represents the atomic ratio of the M element to the sum of the Al element, the Ti element, and the M element, and a, b, and c are 0.30 ≦ a ≦ 0.70, 0 30 ≦ b ≦ 0.70, 0 ≦ c ≦ 0.20, and a + b + c = 1 are satisfied. ].

When a is less than 0.30, the average particle diameter of (Al _a Ti _b M _c ) N particles constituting the lowermost layer becomes large, and the effect of minimizing the peeled area of the coating layer becomes small. On the other hand, when a exceeds 0.70, the amount of Ti element is relatively reduced, the chemical affinity of the coating layer with the base material is significantly reduced, and the lowermost layer includes a crystal structure other than cubic. For this reason, the adhesion strength between the base material and the lowermost layer is lowered, and as a result, large peeling of the coating layer is likely to occur.

When b is less than 0.30, the amount of Al element is relatively increased, and the adhesion strength between the base material and the lowermost layer is lowered. On the other hand, when b exceeds 0.70, the amount of Al element is relatively reduced, so that the average particle diameter of (Al _a Ti _b _Mc ) N particles constituting the lowermost layer becomes large, and the peel resistance decreases. .

The lowermost layer contains at least one element M selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, B and Si in addition to Al and Ti elements. However, if c is in the range of 0 or more and 0.20 or less, the average particle diameter of the (Al _a Ti _b M _c ) N particles constituting the lowermost layer becomes small, and the peel resistance of the coating layer is reduced. improves. On the other hand, when c exceeds 0.20, the adhesion strength between the base material and the lowermost layer is remarkably lowered, and the cutting performance of the coated cutting tool is lowered.

From the above, 0.30 ≦ a ≦ 0.70, 0.30 ≦ b ≦ 0.70, 0 ≦ c ≦ 0.20, and a + b + c = 1. Among them, when a is 0.50 or more and b is 0.50 or less, the average particle diameter of (Al _a Ti _b _Mc ) N particles constituting the lowermost layer tends to be small, and the peel resistance of the coating layer is improved. Since there is a tendency to improve, it is more preferable that 0.50 ≦ a ≦ 0.70, 0.30 ≦ b ≦ 0.50, 0 ≦ c ≦ 0.20, and a + b + c = 1. Among these, 0.60 ≦ a ≦ 0.70, 0.30 ≦ b ≦ 0.40, 0 ≦ c ≦ 0.10, and a + b + c = 1 are more preferable.

In another aspect of the present invention, the composition of particles constituting the lowermost layer of the coated tool in the coated cutting tool of the present invention is (Al _d Cr _e L _f ) N [where L is Ti, Zr, Hf, V Represents at least one element selected from the group consisting of Nb, Ta, Mo, W, Y, B and Si, d represents the atomic ratio of the Al element to the sum of the Al element, Cr element and L element; e represents the atomic ratio of the Cr element to the sum of the Al element, Cr element, and L element, f represents the atomic ratio of the L element to the sum of the Al element, Cr element, and L element, and d, e, and f are 0 20 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.80, 0 ≦ f ≦ 0.20, d + e + f = 1 are satisfied. ].

When d is less than 0.20, the average particle diameter of the (Al _d Cr _e L _f ) N particles constituting the lowermost layer becomes large, and the peel resistance of the coating layer is lowered. On the other hand, if d exceeds 0.75, the lowermost layer includes a crystal structure other than cubic crystals, so that the adhesion strength between the base material and the lowermost layer decreases.

When e is less than 0.25, the amount of Al element is relatively increased, and the adhesion strength between the base material and the lowermost layer is lowered. On the other hand, when e exceeds 0.80, the Al element is relatively reduced, the average particle diameter of the (Al _d Cr _e L _f ) N particles constituting the lowermost layer is increased, and the peel resistance of the coating layer is lowered. To do.

The lowermost layer contains at least one element L selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Y, B and Si in addition to Al and Cr elements. If f is in the range of 0 or more and 0.20 or less, the average particle diameter of the (Al _d Cr _e L _f ) N particles constituting the lowermost layer becomes small, and the peel resistance of the coating layer is reduced. improves. On the other hand, when f exceeds 0.20, the adhesion strength between the base material and the lowermost layer is remarkably lowered, and the cutting performance of the coated cutting tool is lowered.

From the above, 0.20 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.80, 0 ≦ f ≦ 0.20, and d + e + f = 1. Among them, when d is 0.40 or more and e is 0.60 or less, the average particle diameter of (Al _d Cr _e L _f ) N particles constituting the lowermost layer tends to be small, and the peel resistance of the coating layer is reduced. Since there is a tendency to improve, it is more preferable that 0.40 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.60, 0 ≦ f ≦ 0.20, d + e + f = 1. Among them, d ≧ e, and 0.40 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.50, 0 ≦ f ≦ 0.20, and d + e + f = 1 constitute the lowermost layer (Al _d The average particle diameter of the Cr _e L _f ) N particles is small, and the peel resistance of the coating layer is improved, which is more preferable.

The composition of the lowermost layer in the coating layer of the coated cutting tool of the present invention is an energy dispersion attached to an electron microscope such as a scanning electron microscope (SEM), a field emission scanning electron microscope (FE-SEM), or a transmission electron microscope (TEM). It can be measured using a type X-ray analyzer (EDS), a wavelength dispersive X-ray analyzer (WDS), or the like.

The average particle size of particles ((Al _a Ti _b M _c ) N or (Al _d Cr _e L _f ) N particles, hereinafter also referred to as “lowermost layer constituting particles”) constituting the lowermost layer is 400 nm or less. By this, the peeling area of a coating layer is minimized, the processing distance of the coated cutting tool of this invention becomes long, and the effect that a tool life becomes long is acquired. The reason is considered as follows.

When the work material is welded to the surface of the coating layer during the cutting process, it is considered that the cutting resistance increases at the welded portion, and cracks are generated from that portion. When the crack reaches the interface between the coating layer and the substrate, it is considered that the coating layer peels off.

FIG. 1 is a conceptual diagram of a cross-sectional structure of a coated cutting tool in which the average particle diameter of the lowest layer constituent particles is large. The tool includes a base material 1 and a coating layer 2, and the coating layer 2 includes a lowermost layer 3 and an upper layer 4. When cutting is performed under heavy cutting conditions, for example, the work material is welded to a portion indicated by reference numeral 5, and a crack 7 is generated from the portion, and peeling occurs when this reaches the interface between the coating layer 2 and the substrate 1. Is considered to occur. And since the average particle diameter of the constituent particles of the lowermost layer 3 is large in the coated cutting tool of FIG.

On the other hand, FIG. 2 is a conceptual diagram of a cross-sectional structure of a coated cutting tool in which the average particle diameter of the lowest layer constituent particles is small. The tool includes a base material 8 and a coating layer 9, and the coating layer 9 includes a lowermost layer 10 and an upper layer 11. In this coated cutting tool, since the average particle diameter of the particles constituting the lowermost layer 10 is small, the work material is welded to the portion indicated by reference numeral 12, and cracks 14 are generated from the welded material. Even if the interface is reached, the part 13 to be peeled is considered to be small.

Therefore, in the coated cutting tool of the present invention, the average particle size of the lowermost layer constituting particles is set to 400 nm or less. Since the adhesion strength between the base material and the lowermost layer tends to decrease when the average particle size of the lowermost layer constituting particles is less than 10 nm, the average particle size of the lowermost layer constituting particles is preferably 10 to 400 nm. From the viewpoint of reducing the peeled area of the coating layer, the average particle size of the lowermost layer constituting particles is particularly preferably 20 to 100 nm.

In the present invention, the average particle diameter of the lowermost layer constituting particles is measured by the surface texture of the lowermost layer obtained by removing the upper layer of the coated cutting tool. Examples of the method for removing the upper layer include a method of grinding with a diamond grindstone and then polishing with diamond paste or colloidal silica, ion milling, and the like. The surface structure of the lowermost layer that appears after removing the upper layer is observed with a field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), electron backscatter diffraction (EBSD), etc. The average particle size of the particles can be measured.

Specifically, the surface texture of the lowermost layer obtained by removing the upper layer is observed. The diameter of a circle having an area equal to the area of the lowest layer constituting particle is defined as the particle diameter of the particle, and the particle diameter of each particle in a fixed visual field (measurement range) is obtained. Then, a particle size distribution diagram including a vertical axis indicating the area ratio of all the particles included in each of the sections is created. Next, the central value of the 5 nm interval division (for example, the central value of the 5-10 nm division is 7.5 nm) and the area ratio of all the particles included in the division are multiplied. The area ratio is an area ratio occupied by all particles (for example, all particles having a particle diameter of 5 to 10 nm) included in a certain division in the entire measurement range (for example, 2 μm × 2 μm). The sum of all values obtained by multiplying the center value of the 5-nm interval division and the area ratio of all the particles contained in the division is defined as the average particle size of the lowest layer constituent particles.

In addition, as a measuring device for the surface texture of the lowermost layer, EBSD is preferable because the grain boundary of particles becomes clear. The EBSD is preferably set so that a boundary having a step size of 0.01 μm, a measurement range of 2 μm × 2 μm, and an orientation difference of 5 ° or more is regarded as a grain boundary.

The lowermost layer of the coating layer in the coated cutting tool of the present invention composed of the specific particles described above is excellent in peeling resistance. Therefore, the peeling resistance of the coating layer is improved, the working distance of the coated cutting tool of the present invention can be increased, and the tool life can be extended.

The average layer thickness of the lowermost layer is preferably 0.1 to 1 μm. When the average layer thickness of the lowermost layer is less than 0.1 μm, the effect of improving the peel resistance tends to be reduced. On the other hand, when the average layer thickness of the lowermost layer exceeds 1 μm, This is because the adhesion strength tends to decrease. The average layer thickness of the lowest layer can be measured using an optical microscope, a scanning electron microscope (SEM), a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), or the like.

Next, the upper layer constituting the coating layer of the coated cutting tool of the present invention will be described. The upper layer is not particularly limited as long as it is used as having a function required for a coated cutting tool such as wear resistance, fracture resistance, or welding resistance. Among them, the upper layer is made of at least one metal element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, Al and Si; A single-layer or multi-layer structure comprising at least one selected from the group consisting of at least one compound selected from the group consisting of at least one non-metallic element selected from carbon, nitrogen, oxygen and boron. This is more preferable because the wear resistance of the coated cutting tool is improved. Note that the composition of the upper layer is different from the composition of the lowermost layer.

Among them, it is more preferable that the upper layer is a multilayer structure because the wear resistance of the coated cutting tool is suitably improved. As a specific mode in the case where the upper layer is a multilayer structure, a mode in which layers made of the above metals or compounds are laminated with an average layer thickness of 2 nm to 10 μm can be mentioned. It is also preferable that the two or more layers having different compositions include one or more laminated structures in which the average layer thickness of each layer is periodically laminated with a thickness of 2 nm to 500 nm. Here, periodically laminating means that the layers are laminated with a certain periodicity, for example, two or more layers having different compositions are alternately laminated.

In the present invention, the composition of the upper layer and the average layer thickness of each layer when the upper layer is a multilayer structure can be measured by the same method as that for the lowermost layer.

The average layer thickness of the entire upper layer in the coated cutting tool of the present invention described above is preferably 0.2 to 10 μm. This is because if the average layer thickness of the entire upper layer is less than 0.2 μm, the effect of improving the wear resistance of the coated cutting tool may be small, and if it exceeds 10 μm, the coating layer may easily peel from the substrate. It is. The average layer thickness of the entire upper layer of the present invention can be measured by the same method as that for the lowermost layer.

The coated cutting tool of the present invention can be produced by a conventional physical vapor deposition method, and can be produced, for example, by the following method.

In the reaction vessel of the arc ion plating apparatus, a metal evaporation source having the composition of the coating layer (lowermost layer, upper layer) is installed. The prepared substrate is placed in a reaction vessel of an arc ion plating apparatus. Preferably, the base material is subjected to ion bombardment treatment before forming the lowermost layer.

After the ion bombardment treatment, the inside of the reaction vessel is evacuated to 1 × 10 ⁻² Pa or less, and a reaction gas such as N ₂ as a lowermost raw material is introduced into the reaction vessel, and the atmosphere in the reaction vessel is changed. A reactive gas such as N _{2 is used} as a raw material for the lowermost layer. Then, the pressure in the reaction vessel is set to 0.5 to 5.0 Pa, and the base material is heated by a furnace heater so that the temperature of the base material is higher than 750 ° C.

Subsequently, under the conditions that the bias voltage applied to the substrate is −10 to −150 V, the magnetic flux density at the center of the metal evaporation source as the lowermost layer raw material is 13 mT to 17 mT, and the arc current is 80 to 150 A. A lowermost layer may be formed on the surface of the material. By setting the temperature of the base material to over 750 ° C. and setting the magnetic flux density at the center of the metal evaporation source to 13 mT to 17 mT, the average particle size of the lowermost layer can be reduced.

In addition, since the maximum temperature of a general arc ion plating apparatus is 1000 ° C., the temperature of the base material when the lowermost layer is formed is preferably over 750 ° C. and 1000 ° C. or less, and is 800 ° C. or more and 950 ° C. or less. And more preferred. After forming the lowermost layer on the base material in this way and further forming an upper layer, the coated cutting tool of the present invention can be obtained.

The upper layer can be manufactured, for example, by the following method. After forming the lowermost layer, the bias voltage applied to the base material is −10 to −150 V, the base material temperature is 600 ° C., the magnetic flux density at the center of the metal evaporation source as the upper layer raw material is 5 mT to 15 mT, and the arc The upper layer is preferably formed under the condition that the current is 80 to 150 A.

When the upper layer is a multilayer structure, a bias voltage of −10 to −150 V is applied to the substrate, the temperature of the substrate is 600 ° C., the magnetic flux density at the center of the metal evaporation source is 5 mT to 15 mT, Each layer can be formed on the lowermost surface by evaporating a metal evaporation source corresponding to the metal component by arc discharge.

When two or more kinds of metal evaporation sources placed at separate positions are simultaneously evaporated by arc discharge, and a rotary table on which a substrate is fixed is rotated to form a layer constituting a multilayer structure, a reaction vessel The layer thickness of each layer constituting the multilayer structure can be controlled by adjusting the number of revolutions of the turntable to which the substrate is fixed. When two or more types of metal evaporation sources are alternately evaporated by arc discharge to form a layer constituting a multilayer structure, the multilayer structure is configured by adjusting the arc discharge time of each metal evaporation source. The layer thickness of each layer can be controlled.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, the composition and average layer thickness of each coating layer in the coated cutting tools of the invention and comparative products manufactured below were measured, and the average particle size of the lowest layer constituent particles was measured as follows.

<Composition of each layer>
The cross section of the coated cutting tool sample facing the metal evaporation source was mirror-polished with diamond paste in the reaction vessel of the arc ion plating apparatus used for the manufacture of the inventive and comparative coated cutting tools. From the cross section of the obtained sample, the composition of each layer of the coating layer was measured using a scanning electron microscope S-6600 manufactured by Hitachi High-Technologies Corporation and an EDS attached to a transmission electron microscope.

<Average thickness of each layer>
For the average layer thickness of each layer of the coating layer in the sample (when the upper layer is a multilayer structure, the average layer thickness of each layer constituting it), using an optical microscope, scanning electron microscope S-6600 and transmission electron microscope, The cross section of the sample on the side facing the evaporation source was mirror-polished with diamond paste, the cross section of the obtained sample was measured at five locations, and the average value was obtained.

<Average particle size of the lowest layer constituent particles>
The average particle size of the lowermost layer constituting particles of the coated cutting tool samples of the invention and the comparative product was measured as follows. The upper layer formed on the surface of the lowermost layer was removed by ion milling. Using the EBSD device manufactured by TSL Solutions Co., Ltd., the step size is set to 0.01 μm, the measurement range is set to 2 μm × 2 μm, and the boundary where the orientation difference is 5 ° or more is used for the surface of the lowermost layer that appears after removing the upper layer The average particle diameter of the lowermost layer constituting particles was determined from the image of the surface texture of the lowermost layer as the boundary.

Specifically, from the image of the surface texture of the lowermost layer with the boundary having an orientation difference of 5 ° or more as the grain boundary, the diameter of a circle having an area equal to the area of the constituent particles of the lowermost layer is used as the particle diameter of the particle. The particle size distribution chart was created by determining the particle size of each particle in the measurement range and including a horizontal axis indicating the particle size divided at intervals of 5 nm and a vertical axis indicating the area ratio of all particles included in the interval of 5 nm intervals. .

Next, the center value of the particle size classification was multiplied by the area ratio of all the particles included in the classification. Then, all the values obtained by multiplying the median value of the particle size classification and the area ratio of all the particles contained in the classification were summed, and the obtained value was defined as the average particle size of the lowermost layer constituting particles.

[Manufacture of coated cutting tools]
As a base material, an ISO standard SEEN1204 insert-shaped cemented carbide equivalent to K20 was prepared.

For inventive products 1 to 20, a metal evaporation source having the composition of the coating layers (lowermost layer and uppermost layer) shown in Table 1 was installed in the reaction vessel of the arc ion plating apparatus. Subsequently, the base material is attached to a sample holder in the reaction vessel of the arc ion plating apparatus, the pressure in the reaction vessel is set to a vacuum of 1 × 10 ⁻² Pa or less, and the temperature of the base material is 500 ° C. with a furnace heater. Heated until.

After the temperature of the substrate reached 500 ° C., Ar gas was introduced until the pressure in the reaction vessel reached 5 Pa, the atmosphere in the reaction vessel was set to Ar atmosphere, and the pressure in the reaction vessel was set to 5 Pa. Then, Ar ion bombardment treatment was performed under ion bombardment conditions in which a bias voltage of −1000 V was applied to the substrate.

After Ar ion bombardment treatment, the pressure in the reaction vessel is reduced to a vacuum of 1 × 10 ⁻² Pa or less, the Ar gas is discharged, and N ₂ gas, which is the lowermost raw material, is introduced into the reaction vessel. The inside atmosphere was a nitrogen atmosphere. Subsequently, the pressure in the reaction vessel was set to 3 Pa, and the base material was heated with an in-furnace heater to set the temperature of the base material to 800 ° C. The composition shown in Table 1 on the surface of the base material under the coating conditions in which the bias voltage applied to the base material is −50 V, the magnetic flux density at the center of the metal evaporation source as the lowermost raw material is 15 mT, and the arc current is 150 A. The bottom layer of was formed.

After the lowermost layer was formed, the atmosphere in the reaction vessel was changed to a nitrogen atmosphere, the pressure in the reaction vessel was set to 3 Pa, and the substrate was heated with a furnace heater to set the temperature of the substrate to 600 ° C. Under the coating conditions where the bias voltage applied to the substrate is −50 V, the magnetic flux density at the center of the metal evaporation source that is the raw material of the upper layer is 15 mT, and the arc current is 150 A, the surface layer has the composition shown in Table 1. An upper layer was formed. The resulting inventive coated cutting tool was then cooled and removed from the reaction vessel.

For Invention Products 21 and 22, a metal evaporation source having the composition of the coating layers (lowermost layer and uppermost layer) shown in Table 1 was installed in the reaction vessel of the arc ion plating apparatus. Subsequently, the base material was attached to a sample holder in the reaction vessel of the arc ion plating apparatus, and Ar ion bombardment treatment was performed under the same conditions as invented products 1 to 20.

After forming the lowermost layer, the atmosphere in the reaction vessel is continuously changed to a mixed gas atmosphere in which the partial pressure ratio of N ₂ gas and CH ₄ gas is N ₂ : CH ₄ = 1: 1. The pressure was set to 2.7 Pa, and the temperature of the substrate was set to 600 ° C. by heating the substrate with a furnace heater. Under the coating conditions where the bias voltage applied to the substrate is −50 V, the magnetic flux density at the center of the metal evaporation source that is the raw material of the upper layer is 15 mT, and the arc current is 150 A, the surface layer has the composition shown in Table 1. An upper layer was formed. The resulting inventive coated cutting tool was then cooled and removed from the reaction vessel.

For Invention Products 23 to 30, a metal evaporation source having the composition of the coating layer (lowermost layer, uppermost layer) shown in Table 2 was installed in the reaction vessel of the arc ion plating apparatus. Subsequently, the base material was attached to a sample holder in the reaction vessel of the arc ion plating apparatus, and Ar ion bombardment treatment was performed under the same conditions as invented products 1 to 20.

After Ar ion bombardment treatment, the pressure in the reaction vessel is reduced to a vacuum of 1 × 10 ⁻² Pa or less, the Ar gas is discharged, and N ₂ gas, which is the lowermost raw material, is introduced into the reaction vessel. The atmosphere inside was a nitrogen atmosphere, and the pressure in the reaction vessel was 3 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 800 degreeC. The composition shown in Table 2 on the surface of the base material under the coating conditions in which the bias voltage applied to the base material is −50 V, the magnetic flux density at the center of the metal evaporation source as the lowermost raw material is 15 mT, and the arc current is 150 A. The bottom layer of was formed.

After the lowermost layer was formed, the atmosphere in the reaction vessel was changed to a nitrogen atmosphere, the pressure in the reaction vessel was set to 3 Pa, and the substrate was heated with a furnace heater to set the temperature of the substrate to 600 ° C. Then, each metal evaporation source is alternately arced under a coating condition in which the bias voltage applied to the substrate is −50 V, the magnetic flux density at the center of each metal evaporation source serving as the upper layer material is 15 mT, and the arc current is 150 A. Evaporated by discharge. As a result, an upper layer having an alternately laminated structure composed of A layers and B layers having different compositions shown in Table 2 was formed. At this time, the arc discharge times of the A layer and the B layer were adjusted to control the average layer thickness of the A layer and the average layer thickness of the B layer to be 100 nm, respectively. After forming the upper layer of this alternating laminate structure, the resulting inventive coated cutting tool was cooled and removed from the reaction vessel.

For comparative products 1 to 3, and 6, a metal evaporation source having the composition of the coating layers (lowermost layer and uppermost layer) shown in Table 3 was installed in the reaction vessel of the arc ion plating apparatus. Subsequently, the base material was attached to a sample holder in the reaction vessel of the arc ion plating apparatus, and Ar ion bombardment treatment was performed under the same conditions as invented products 1 to 20.

After the Ar ion bombardment treatment, the pressure in the reaction vessel is reduced to a vacuum of 1 × 10 ⁻² Pa or less, and N ₂ gas as the lowermost raw material is introduced into the reaction vessel, and the atmosphere in the reaction vessel is changed. A nitrogen atmosphere was set, and the pressure in the reaction vessel was 3 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 750 degreeC. The composition shown in Table 3 on the surface of the base material under the coating conditions in which the bias voltage applied to the base material is −50 V, the magnetic flux density at the center of the metal evaporation source that is the lowermost raw material is 15 mT, and the arc current is 150 A. The bottom layer of was formed.

After the lowermost layer was formed, the atmosphere in the reaction vessel was changed to a nitrogen atmosphere, the pressure in the reaction vessel was set to 3 Pa, and the substrate was heated with a furnace heater to set the temperature of the substrate to 600 ° C. Under the coating conditions where the bias voltage applied to the substrate is -50 V, the magnetic flux density at the center of the metal evaporation source as the upper layer raw material is 15 mT, and the arc current is 150 A, the composition shown in Table 3 is formed on the surface of the lowermost layer. An upper layer was formed. The resulting coated coated cutting tool was cooled and removed from the reaction vessel.

For Comparative Product 4, a metal evaporation source having the composition of the coating layers (lowermost layer and upper layer) shown in Table 3 was installed in the reaction vessel of the arc ion plating apparatus, and the base material was reacted by the arc ion plating apparatus. The sample was attached to the sample holder in the container, and Ar ion bombardment treatment was performed under the same conditions as invented products 1-20.

After the Ar ion bombardment treatment, the pressure in the reaction vessel is reduced to a vacuum of 1 × 10 ⁻² Pa or less, and N ₂ gas as the lowermost raw material is introduced into the reaction vessel, and the atmosphere in the reaction vessel is changed. A nitrogen atmosphere was set, and the pressure in the reaction vessel was 3 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 750 degreeC. The composition shown in Table 3 on the surface of the base material under the coating conditions in which the bias voltage applied to the base material is −50 V, the magnetic flux density at the center of the metal evaporation source as the lowermost layer raw material is 5 mT, and the arc current is 150 A. The bottom layer of was formed.

After the lowermost layer was formed, the atmosphere in the reaction vessel was changed to a nitrogen atmosphere, the pressure in the reaction vessel was set to 3 Pa, and the substrate was heated with a furnace heater to set the temperature of the substrate to 600 ° C. Under the coating conditions where the bias voltage applied to the substrate is -50 V, the magnetic flux density at the center of the metal evaporation source as the upper layer raw material is 15 mT, and the arc current is 150 A, the composition shown in Table 3 is formed on the surface of the lowermost layer. An upper layer was formed. Then, the coated cutting tool of the comparative product 4 obtained was cooled and taken out from the reaction vessel.

For Comparative Product 5, a metal evaporation source having the composition of the coating layer (lowermost layer, uppermost layer) shown in Table 3 was installed in the reaction vessel of the arc ion plating apparatus. Subsequently, the base material was attached to a sample holder in the reaction vessel of the arc ion plating apparatus, and Ar ion bombardment treatment was performed under the same conditions as invented products 1 to 20.

After Ar ion bombardment treatment, the inside of the reaction vessel is evacuated to 1 × 10 ⁻² Pa or less, and N ₂ gas as a lowermost raw material is introduced into the reaction vessel, so that the atmosphere in the reaction vessel is a nitrogen atmosphere And the pressure in the reaction vessel was 3 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 500 degreeC. The composition shown in Table 3 on the surface of the base material under the coating conditions in which the bias voltage applied to the base material is −50 V, the magnetic flux density at the center of the metal evaporation source that is the lowermost raw material is 15 mT, and the arc current is 150 A. The bottom layer of was formed.

After forming the lowermost layer, the atmosphere in the reaction vessel was continuously changed to a nitrogen atmosphere, and the pressure in the reaction vessel was set to 3 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 600 degreeC. Under the coating conditions where the bias voltage applied to the substrate is -50 V, the magnetic flux density at the center of the metal evaporation source as the upper layer raw material is 15 mT, and the arc current is 150 A, the composition shown in Table 3 is formed on the surface of the lowermost layer. An upper layer was formed. The resulting coated cutting tool of Comparative Product 5 was cooled and removed from the reaction vessel.

For Comparative Product 7, a metal evaporation source having the composition of the coating layer (lowermost layer, uppermost layer) shown in Table 3 was installed in the reaction vessel of the arc ion plating apparatus. Subsequently, the base material was attached to a sample holder in the reaction vessel of the arc ion plating apparatus, and Ar ion bombardment treatment was performed under the same conditions as invented products 1 to 20.

After Ar ion bombardment treatment, the pressure in the reaction vessel is reduced to a vacuum of 1 × 10 ⁻² Pa or less, the Ar gas is discharged, and N ₂ gas, which is the lowermost raw material, is introduced into the reaction vessel. The atmosphere inside was a nitrogen atmosphere, and the pressure in the reaction vessel was 3 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 750 degreeC. The composition shown in Table 3 on the surface of the base material under the coating conditions in which the bias voltage applied to the base material is −50 V, the magnetic flux density at the center of the metal evaporation source that is the lowermost raw material is 15 mT, and the arc current is 150 A. The bottom layer of was formed.

After forming the lowermost layer, the atmosphere in the reaction vessel is continuously changed to a mixed gas atmosphere in which the partial pressure ratio of N ₂ gas and CH ₄ gas is N ₂ : CH ₄ = 1: 1. The pressure was 2.7 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 600 degreeC. Under the coating conditions where the bias voltage applied to the substrate is -50 V, the magnetic flux density at the center of the metal evaporation source as the upper layer raw material is 15 mT, and the arc current is 150 A, the composition shown in Table 3 is formed on the surface of the lowermost layer. An upper layer was formed. Then, the coated cutting tool of the comparative product 7 obtained was cooled and taken out from the reaction vessel.

For Comparative Products 8 and 9, a metal evaporation source having the composition of the coating layer (lowermost layer, uppermost layer) shown in Table 3 was installed in the reaction vessel of the arc ion plating apparatus. Subsequently, the base material was attached to a sample holder in the reaction vessel of the arc ion plating apparatus, and Ar ion bombardment treatment was performed under the same conditions as invented products 1 to 20.

After forming the lowermost layer, the atmosphere in the reaction vessel was continuously changed to a nitrogen atmosphere, and the pressure in the reaction vessel was set to 3 Pa. Then, the base material was heated with the furnace heater and the temperature of the base material was 600 degreeC. A bias voltage applied to the substrate is set to −50 V, a magnetic flux density at the center of each metal evaporation source as an upper layer material is set to 15 mT, and an arc current is set to 150 A. Evaporated. Thus, an upper layer having an alternately laminated structure composed of A layers and B layers having different compositions shown in Table 3 was formed. At this time, the arc discharge times of the A layer and the B layer were adjusted to control the average layer thickness of the A layer and the average layer thickness of the B layer to be 100 nm, respectively. After forming the upper layer of the alternately laminated structure, the obtained comparative coated cutting tool was cooled and taken out from the reaction vessel.

[Cutting test]
The obtained invention and comparative coated cutting tool samples were attached to the following cutter, and the cutting test was performed under the following conditions.

<Cutting test conditions>
Work material: FCD600,
Cutting speed: 150 m / min,
Feed: 0.2mm / tooth,
Cutting depth: 2.0mm
Cutting width: 46 mm
Coolant: Not used (dry processing)
Machining distance: (1) 0.8 m, (2) 2.0 m, (3) Machining distance until tool life,
Judgment of tool life: The tool life is determined when the maximum flank wear width reaches 0.2 mm.
Cutter: A cutter with an effective diameter of 80 mm.

In order to evaluate the peel resistance of the coating layer, the coating layer was peeled off for (1) a sample cut to a working distance of 0.8 m and (2) a sample cut to a working distance of 2.0 m. The area where the material was exposed was measured. Specifically, after the cutting test, the work material welded to the sample surface is removed with aqua regia, the sample surface is observed with SEM, and the substrate is exposed from the SEM composition image using image analysis software. The measured area (mm ² ) was measured. The areas (mm ² ) where the substrate was exposed are shown in Tables 4 and 5. Further, (3) Tables 4 and 5 show the processing distances of the samples processed until reaching the tool life.

As shown in Tables 4 and 5, it can be seen that the inventive product has a smaller exposed area of the base material than the comparative product at both processing distances of 0.8 m and 2.0 m, and the coating layer is excellent in peel resistance. Moreover, the processing distance until the tool life of the invention product is longer than that of the comparative product. This indicates that the tool life of the inventive product is longer than that of the comparative product.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Covering layer 3 Bottom layer 4 Upper layer 5 Part where work material is welded 6 Part where coating layer peels 7 Crack 8 Base material 9 Covering layer 10 Bottom layer 11 Upper layer 12 Part where work material is welded 13 Covering layer The part that peels

Claims

It consists of a substrate and a coating layer formed on the surface of the substrate, and the coating layer consists of an upper layer on the surface side and a lowermost layer on the substrate side,
The lowest layer is (Al a Ti b M c ) N [wherein M is at least one element selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, B and Si. A represents the atomic ratio of the Al element to the sum of the Al element, Ti element and M element, b represents the atomic ratio of the Ti element to the sum of the Al element, Ti element and M element, and c represents the Al element and It represents the atomic ratio of M element to the total of Ti element and M element, and a, b and c are 0.30 ≦ a ≦ 0.70, 0.30 ≦ b ≦ 0.70, 0 ≦ c ≦ 0.20. A + b + c = 1 is satisfied. ],
A coated cutting tool in which the average particle diameter of (Al a Ti b M c ) N particles constituting the lowermost layer is 400 nm or less.
The coated cutting tool according to claim 1, wherein a, b, and c satisfy 0.50 ≦ a ≦ 0.70, 0.30 ≦ b ≦ 0.50, 0 ≦ c ≦ 0.20, and a + b + c = 1. .
The coated cutting tool according to claim 1 or 2, wherein the average particle diameter of (Al a Ti b M c ) N particles constituting the lowermost layer is 10 to 400 nm.
The coated cutting tool according to any one of claims 1 to 3, wherein an average layer thickness of the lowermost layer is 0.1 to 1 µm.
The upper layer is a metal composed of at least one metal element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, Al and Si; and at least one of these metal elements The single-layer or multi-layer structure comprising at least one selected from the group consisting of compounds consisting of at least one non-metallic element selected from carbon, nitrogen, oxygen and boron. The coated cutting tool according to Item 1.
The coated cutting tool according to any one of claims 1 to 5, wherein an average layer thickness of the entire upper layer is 0.2 to 10 µm.
It consists of a substrate and a coating layer formed on the surface of the substrate, and the coating layer consists of an upper layer on the surface side and a lowermost layer on the substrate side,
The lowermost layer is (Al d Cr e L f ) N [wherein L is at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Y, B and Si. D represents the atomic ratio of the Al element to the sum of the Al element, Cr element and L element, e represents the atomic ratio of the Cr element to the sum of the Al element, Cr element and L element, and f represents the Al element and This represents the atomic ratio of the L element to the total of the Cr element and the L element, and d, e, and f are 0.20 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.80, and 0 ≦ f ≦ 0.20. , D + e + f = 1 is satisfied. ],
A coated cutting tool in which the average particle diameter of (Al d Cr e L f ) N particles constituting the lowermost layer is 400 nm or less.
The coated cutting tool according to claim 7, wherein d, e, and f satisfy 0.40 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.60, 0 ≦ f ≦ 0.20, and d + e + f = 1. .
The d, e, and f satisfy the following conditions: 0.40 ≦ d ≦ 0.75, 0.25 ≦ e ≦ 0.60, 0 ≦ f ≦ 0.20, d ≧ e, d + e + f = 1. Coated cutting tool described in 1.
The coated cutting tool according to any one of claims 7 to 9, wherein an average particle diameter of (Al d Cr e L f ) N particles constituting the lowermost layer is 10 to 400 nm.
The coated cutting tool according to any one of claims 7 to 10, wherein an average layer thickness of the lowermost layer is 0.1 to 1 µm.
The upper layer is a metal composed of at least one metal element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, Al and Si; and at least one of these metal elements 12. A single-layer or multi-layer structure comprising at least one selected from the group consisting of compounds consisting of at least one non-metallic element selected from carbon, nitrogen, oxygen and boron. The coated cutting tool according to Item 1.
The coated cutting tool according to any one of claims 7 to 12, wherein an average layer thickness of the entire upper layer is 0.2 to 10 µm.