WO2011007848A1

WO2011007848A1 - Hard film-coated tool and manufacturing method for the same

Info

Publication number: WO2011007848A1
Application number: PCT/JP2010/062016
Authority: WO
Inventors: 有三福永; 和幸久保田; 正和伊坂; 仁志大沼; 正和塩野入
Original assignee: 日立ツール株式会社
Priority date: 2009-07-15
Filing date: 2010-07-15
Publication date: 2011-01-20
Also published as: JP5614405B2; JPWO2011007848A1

Abstract

A hard film-coated tool has a hard lower layer, a hard intermediate layer, and a hard upper layer, all formed on a substrate by a physical vapor deposition method. The upper layer has a composition represented by (Al_xCr_y)_cO_d and has an α crystal structure of which TC(006) is not less than 1.3. The intermediate layer has a gradient composition in which the oxygen concentration increases from the lower layer side toward the upper layer side and the nitrogen concentration decreases from the lower layer side toward the upper layer side. The average composition of the intermediate layer is represented by (Al_sCr_t)_a(N_vO_w)_b.

Description

Hard film coated tool and manufacturing method thereof

The present invention relates to a hard film-coated tool having a hard film formed by physical vapor deposition and having excellent adhesion and chipping resistance, and a method for producing the same.

Since the α-type (Al, Cr) ₂ O ₃ film has excellent heat resistance and oxidation resistance, it has been used as an upper layer of a hard film provided on a tool. The α-type (Al, Cr) ₂ O ₃ film can be formed by chemical vapor deposition and physical vapor deposition. In the case of chemical vapor deposition, an α-type (Al, Cr) ₂ O ₃ film with excellent adhesion can be obtained, but the film formation temperature is as high as about 1000 ° C. There is a problem that tensile stress remains in the chip and chipping is likely to occur.

On the other hand, in the physical vapor deposition method, the film forming temperature is as low as around 500 ° C., so that not only can the film be formed on various substrates, but also a compressive stress remains in the obtained film, so that a film having excellent fracture resistance can be obtained. . However, the α-type (Al, Cr) ₂ O ₃ film formed by physical vapor deposition is inferior in adhesion, and has a problem that chipping easily occurs due to falling off of crystal grains as well as easy peeling. Therefore, development of a technique for forming a hard film that hardly causes peeling or chipping by physical vapor deposition is required.

Japanese Patent No. 3323534 discloses a cutting tool in which a hard layer made of (Al, Cr) ₂ O ₃ crystals containing 10 to 50 atomic% of chromium is formed. In this document, a crystalline hard layer, which can be obtained only by a high temperature CVD method, was obtained at a film forming temperature of less than 1000 ° C. by a very simple measure of adding chromium to aluminum. However, this document does not disclose any combination of (Al, Cr) ₂ O ₃ hard layer and intermediate layer.

Japanese Patent Laid-Open No. 2008-168365 is a surface-coated cutting tool in which at least an aluminum oxide multilayer coating is formed on a substrate, wherein the aluminum oxide multilayer coating is a first layer containing aluminum oxide having an α-type crystal structure And a second layer containing aluminum oxide having a γ-type crystal structure, and a thickness of each of the first and second layers is 0.5 to 50 nm. Is disclosed. Table 1 of this document shows that an AlCrN layer having a thickness of 5.0 nm and an AlCrNO layer having a thickness of 4.0 nm are alternately stacked on a TiAlN layer formed on a substrate until the thickness becomes 1.5 μm. 2.0 nm thick γ- (Al, Si) ₂ O ₃ layer containing 7.5 atomic% Si and 3.5 nm thick α- (Al, Cr) ₂ O ₃ layer containing 2.4 atomic% Cr (Example 5). In this surface-coated cutting tool, the composition of the AlCrNO layer is unknown, and a γ- (Al, Si) ₂ O ₃ layer and an α- (Al, Cr) ₂ O ₃ layer coexist. From the film conditions, the α- (Al, Cr) ₂ O ₃ layer has a TC (006) of less than 1.3 and is judged to have low adhesion.

JP 2010-506049 is a PVD coating system for coating tools and the like, which includes at least one mixed oxide mixed crystal coating having a composition of (Me1 _1-x Me2 _x ) ₂ O ₃ , Me1 and Me2 is at least one element of Al, Cr, Fe, Li, Mg, Mn, Nb, Ti, Sb and V, respectively, and the mixed crystal film has a corundum structure in the coating system. A system is disclosed. This document states that it is also possible to produce a double oxide having a corundum type, dichromium trioxide type or hexagonal crystal structure. Further, FIGS. 1A to 1C of this document show the X-ray spectra of the (Al _1-x Cr _x ) ₂ O ₃ film when x = 0.75, 0.50, and 0.30, respectively. Regarding the transition from the generation of the intermediate film to the generation of the mixed oxide film of the double oxide, this document starts the introduction of oxygen gas 5 minutes after turning on the AlCr (50/50) target, and the oxygen gas flow rate is increased to 10%. It is stated that within 50 minutes, the scal is reduced from 50 sccm to 1000 sccm, and at the same time the TiAl (50/50) target is turned off and the nitrogen gas flow is returned to about 100 sccm.

However, as is clear from the X-ray spectra shown in FIG. 1A to FIG. 1C, the (Al _1-x Cr _x ) ₂ O ₃ film of the corundum type structure of JP 2010-506049 is oriented in the (202) plane. Yes. In addition, since this (Al _1-x Cr _x ) ₂ O ₃ film has an equivalent X-ray diffraction intensity ratio TC (006) of less than 1.3, the orientation to the (006) plane is insufficient. Therefore, even if a mixed crystal film made of (Al _0.5 Cr _0.5 ) ₂ O ₃ is formed on an intermediate film made of AlCrON, for example, as in experiment number 93 shown in Table 7, the intermediate film is mixed with the mixed crystal film. Adhesion is not enough.

Accordingly, an object of the present invention is a hard film-coated tool formed on a substrate by forming a hard film composed of a lower layer, an AlCr oxynitride intermediate layer and an AlCr oxide upper layer by a physical vapor deposition method. It is to provide a hard film coated tool having a significantly increased life by improving the adhesion of the upper layer and also improving the chipping resistance of the upper layer, and a method for producing the same.

The hard film coated tool of the present invention is a hard lower layer, an intermediate layer and an upper layer formed on a substrate by physical vapor deposition,
(a) the lower layer is at least one metal element selected from the group consisting of elements IVa, Va and VIa of the periodic table, Al and Si, and at least selected from the group consisting of N, C and B Containing a kind of non-metallic element,
(b) The upper layer has the general formula: (Al _x Cr _y ) _c O _d (where x and y are numbers representing the atomic ratio of Al and Cr, and c and d represent the atomic ratio of AlCr and O) And a composition represented by the following condition: x = 0.1 to 0.4, x + y = 1, c = 1.86 to 2.14, and d = 2.79 to 3.21) TC (006) has an α-type crystal structure of 1.3 or more,
(c) The intermediate layer is made of an oxynitride essentially containing Al and Cr as metal elements, and the oxygen concentration increases from the lower layer side to the upper layer side and the nitrogen concentration decreases from the lower layer side to the upper layer side. The average composition is a general formula: (Al _s Cr _t ) _a (N _v O _w ) _b (where s, t, v, and w are atomic ratios of Al, Cr, N, and O, respectively) A and b are numbers representing the atomic ratio of AlCr and NO, and the following conditions:
s = 0.1-0.4,
s + t = 1,
v = 0.1-0.8,
v + w = 1,
a = 0.3-0.5, and
a + b = 1 is satisfied. ).

It is preferable that the crystal lattice fringes of the intermediate layer and the crystal lattice fringes of the upper layer are at least partially continuous at the interface between them.

The equivalent X-ray diffraction intensity ratio TC (006) of the upper layer is preferably 1.8 or more.

The thickness (Tm) of the intermediate layer is 0.1 to 5 μm, the thickness (Tu) of the upper layer is 0.2 to 8 μm, and preferably satisfies the relationship of Tm ≦ Tu. The thickness of the lower layer is preferably 0.5 to 10 μm.

In the gradient composition of the intermediate layer, the average gradient of the oxygen concentration from the lower layer side to the upper layer side is preferably 10 to 600 atomic% / μm.

In the gradient composition of the intermediate layer, the average gradient of nitrogen concentration from the lower layer side to the upper layer side is preferably −650 to −10 atomic% / μm.

The method of the present invention for producing the hard film coated tool is as follows:
(1) While increasing the flow rate of oxygen gas supplied as a reaction gas from the start to the end of the formation of the intermediate layer, and decreasing the flow rate of nitrogen gas,
(2) The oxygen gas flow rate during the film formation of the upper layer is set to 100 to 600 sccm, and the oxygen partial pressure in the film formation atmosphere is controlled to 0.3 to 2 Pa.

In the above method, in order to prevent the formation of droplets, it is preferable to control the flow rate of oxygen gas during film formation of the upper layer to 300 to 500 cm2.

In the above method, it is preferable that the upper layer oxygen gas flow rate is reached at the end of the formation of the intermediate layer.

The hard film coated tool of the present invention formed by physical vapor deposition has an intermediate layer having a gradient composition between a lower layer having a (111) orientation and an upper layer having a (006) orientation. It is excellent in properties and is particularly suitable for intermittent cutting and the like. Further, according to the method of the present invention, by changing the flow rates of the oxygen gas and the nitrogen gas during film formation of the intermediate layer, and by controlling the flow rate of the oxygen gas during the upper layer film formation and the oxygen partial pressure in the film formation atmosphere, A hard film coated tool having the above characteristics can be manufactured stably.

It is the schematic which shows an example of the AIP apparatus which can be used for this invention. 4 is a graph showing changes in the flow rates of oxygen gas and nitrogen gas in the intermediate layer deposition step in Example 1. FIG. 2 is a graph showing an X-ray diffraction pattern of an upper layer of Example 1. FIG. 2 is a graph showing an oxygen concentration distribution and a nitrogen concentration distribution in an intermediate layer of Example 1. FIG. 2 is a transmission electron micrograph (magnified 2 million times) showing an interface region between an intermediate layer and an upper layer in the hard film-coated tool of Example 1. FIG. FIG. 5 (a) is a schematic diagram of the bag. 10 is a graph showing changes in the flow rates of oxygen gas and nitrogen gas in the intermediate layer deposition step in Example 9. FIG. 6 is a graph showing changes in the flow rates of oxygen gas and nitrogen gas in the intermediate layer deposition step in Comparative Example 1. 6 is a graph showing an oxygen concentration distribution and a nitrogen concentration distribution in an intermediate layer of Comparative Example 1. It is a graph which shows the relationship between TC (006) and the lifetime of the hard film coating tool of an Example and a comparative example.

[1] Hard coating tool
(A) Substrate As the substrate material for the hard coating coated tool of the present invention, cemented carbide, cubic boron nitride (CBN), high speed steel, tool steel, cermet, ceramics, etc. are suitable, especially cemented carbide. Is preferred.

(B) Lower layer The lower layer formed on the substrate by physical vapor deposition comprises at least one metal element selected from the group consisting of elements IVa, Va and VIa of the periodic table, Al and Si, and N, C and A hard film comprising at least one non-metallic element selected from the group consisting of B. As a nonmetallic element, it is preferable that N is essential. Specific examples of the lower layer composition include TiAlN, TiAlNbN, TiAlCrN, AlCrSiN, and CrSiBN. In order to improve the adhesion to the intermediate layer, it is preferable to contain Al or Cr. These lower layers have an fcc structure and are oriented in the (111) plane. The thickness of the lower layer is preferably 0.5 to 10 μm, more preferably 1 to 5 μm, and most preferably 2 to 4 μm.

(C) Middle layer
(1) Average composition The intermediate layer formed on the lower layer by a physical vapor deposition method is a hard film of oxynitride in which Al and Cr are essential as metal elements. The average composition of the intermediate layer is represented by the general formula: (Al _s Cr _t ) _a (N _v O _w ) _b (where s, t, v and w are numbers representing the atomic ratio of Al, Cr, N and O, respectively) A and b are numbers representing the atomic ratio of AlCr and NO, respectively
s = 0.1-0.4,
s + t = 1,
v = 0.1-0.8,
v + w = 1,
a = 0.3-0.5, and
a + b = 1
Satisfy the condition of ). As the average composition, the composition at the center in the thickness direction of the intermediate layer can be used. With this composition, the intermediate layer has an fcc structure oriented in the (111) plane like the lower layer, and has high adhesion to the lower layer.

The sum of the atomic ratio s of Al and the atomic ratio t of Cr (s + t) is 1. s is 0.1 to 0.4, preferably 0.15 to 0.38, and most preferably 0.2 to 0.3. t is 0.9 to 0.6, preferably 0.85 to 0.62, and most preferably 0.8 to 0.7. If s is less than 0.1, the Cr content in the intermediate layer is excessive, the hardness and mechanical strength of the intermediate layer are low, and the adhesion to the lower and upper layers is low. On the other hand, when s exceeds 0.4, the content of Al in the intermediate layer is excessive, and since it has a hexagonal crystal structure, the hardness and mechanical strength of the intermediate layer are also low, and the adhesion between the lower layer and the upper layer is low.

The total (v + w) of the atomic ratio v of nitrogen (N) and the atomic ratio w of oxygen (O) is 1. v is 0.1 to 0.8, preferably 0.2 to 0.7, and most preferably 0.3 to 0.6. w is 0.9 to 0.2, preferably 0.8 to 0.3, and most preferably 0.7 to 0.4. When v is 0.1 to 0.8, the fcc-structured AlCr oxynitride constituting the intermediate layer is oriented so that the (111) plane appears on the surface, and the crystal lattice fringes are at least partially different from the crystal lattice fringes of the upper AlCr oxide Therefore, the adhesion between the intermediate layer and the upper layer is high. When v is less than 0.1, the intermediate layer is not only brittle due to excess oxygen, but also has poor adhesion to the upper layer. On the other hand, if v is more than 0.8, the lattice constant of the intermediate layer is excessive, the consistency with the upper layer AlCr oxide is poor, and the adhesion with the upper layer is poor.

The atomic ratio a of AlCr corresponds to (s + t) / [(s + t) + (v + w)], and the atomic ratio b of NO corresponds to (v + w) / [(s + t) + (v + w)]. a + b is 1. a is 0.3 to 0.5, preferably 0.38 to 0.47, and most preferably 0.4 to 0.45. b is 0.7 to 0.5, preferably 0.62 to 0.53, and most preferably 0.6 to 0.55. When a is less than 0.3, the metal component (Al, Cr) in the intermediate layer is too small and the hardness is insufficient. When a is more than 0.5, there are too many metal components, an intermediate layer having a uniform balance between the metal component and the non-metal component cannot be obtained, and the mechanical strength is inferior.

(2) Gradient composition The lower layer, the upper layer and the intermediate layer have different residual stresses, and if there is a large stress difference between the lower layer and the intermediate layer and between the intermediate layer and the upper layer, delamination may occur. In contrast, the intermediate layer has a gradient composition in which the oxygen concentration increases from the lower layer side to the upper layer side and the nitrogen concentration decreases from the lower layer side to the upper layer side, thereby suppressing a rapid change in residual stress and delamination. It was found that can be suppressed.

As shown in FIG. 4, it is preferable that the oxygen concentration and nitrogen concentration in the intermediate layer change substantially linearly. In this case, since the lattice constant of the intermediate layer changes linearly, sudden changes in residual stress and delamination are further suppressed. Of course, even if the oxygen concentration and nitrogen concentration in the intermediate layer do not change linearly from the lower layer side to the upper layer side (for example, even if there is a region that changes intermittently), the oxygen concentration increases from the lower layer side to the upper layer side. At the same time, if the nitrogen concentration is reduced, a sudden change in residual stress is suppressed, and delamination is suppressed.

In the gradient composition of the intermediate layer, the average gradient of oxygen concentration depends on the film thickness, but is generally 10 to 600 atomic% / μm, preferably 20 to 300 atomic% / μm, more preferably 30 to 200 atomic% / μm. 60 to 150 atomic% / μm is particularly preferable. Since the average gradient of the oxygen concentration becomes smaller as the intermediate layer becomes thicker, if the average gradient of the oxygen concentration is less than 10 atomic% / μm, the intermediate layer becomes too thick, and the chipping resistance of the hard coating is deteriorated. If the average gradient of the oxygen concentration exceeds 600 atomic% / μm, the oxygen concentration changes rapidly, and the meaning of providing an intermediate layer having a gradient composition is lost.

The average gradient of nitrogen concentration is preferably −650 to −10 atomic% / μm, more preferably −330 to −22 atomic% / μm, most preferably −220 to −33 atomic% / μm, and −160 to −70 atoms. % / Μm is particularly preferred. The symbol “−” in the average gradient of nitrogen concentration means that the nitrogen concentration decreases from the lower layer side to the upper layer side. If the absolute value of the average gradient of the nitrogen concentration is less than 10 atomic% / μm, the intermediate layer is too thick, and the chipping resistance of the hard coating is deteriorated. If the absolute value of the average gradient of nitrogen concentration is more than 650 atomic% / μm, the nitrogen concentration changes rapidly, and the meaning of providing an intermediate layer having a gradient composition is lost. The oxygen concentration and the nitrogen concentration can be measured by electron energy loss spectroscopy (EELS) in a local region using a transmission electron microscope (TEM).

(3) Thickness In order to have high impact resistance as well as high adhesion to the lower layer and upper layer, the film thickness (Tm) of the intermediate layer is preferably 0.1-5 μm, more preferably 0.2-3 μm, most preferably 0.3-2 μm Preferably, 0.3 to 1 μm is particularly preferable.

(D) Upper layer
(1) Composition The upper layer formed on the intermediate layer by physical vapor deposition is a hard oxide film that essentially contains Al and Cr as metal elements. The composition of the upper layer is represented by the general formula: (Al _x Cr _y ) _c O _d (where x and y are numbers representing the atomic ratio of Al and Cr, and c and d are numbers representing the atomic ratio of AlCr and O. And x = 0.1 to 0.4, x + y = 1, c = 1.86 to 2.14, and d = 2.79 to 3.21. The sum (x + y) of the atomic ratio x of Al and the atomic ratio y of Cr is 1. x is 0.1 to 0.4, preferably 0.15 to 0.38, and most preferably 0.2 to 0.35. y is 0.9 to 0.6, preferably 0.85 to 0.62, and most preferably 0.8 to 0.65. The upper layer has an α-type crystal structure with x of 0.1 to 0.4. When x is less than 0.1, Cr is excessive, and not only the hardness and mechanical strength of the upper layer are low and the adhesion to the intermediate layer is poor, but also the heat resistance is poor because Cr ₂ O ₃ is excessive. When x exceeds 0.4, the low melting point Al becomes excessive, and the number of atoms that are not normally ionized during film formation increases.Therefore, unreacted metals and abnormally reacted products exist as droplets in the upper layer or on the surface. The layer density is lowered, and the adhesion and chipping resistance are deteriorated.

The upper layer has a basic composition of (AlCr) ₂ O ₃ which is a stoichiometric value, but the composition formed by physical vapor deposition does not necessarily have a stoichiometric value. Therefore, c and d are values within a range where 2 and 3 are discontinued. Specifically, c is 1.86 to 2.14, preferably 1.9 to 2.1, more preferably 1.93 to 2.06. Preferably it is 1.94 to 2.06. Further, d is 2.79 to 3.21, preferably 2.85 to 3.15, more preferably 2.90 to 3.10, and most preferably 2.91 to 3.09.

(2) Crystal structure Since the cutting edge of a hard-coated tool is exposed to cutting heat of 800 ° C or higher, the oxide upper layer must have excellent heat resistance. However, when the oxide upper layer is in a crystal form other than α-type such as γ-type, κ-type, or δ-type, it transforms into α-type and contracts at a high temperature. Further, since compressive stress remains in the hard film formed by physical vapor deposition, the influence of shrinkage due to transformation of the crystal form is great. Therefore, the oxide upper layer is peeled off or chipped from the intermediate layer. However, since the upper layer of the present invention has an α-type crystal structure, it is excellent in adhesion to the intermediate layer, and a hard film coated tool excellent in peeling resistance and chipping resistance can be obtained.

Since AlCr oxide formed by physical vapor deposition has a lower density than AlCr oxide formed by chemical vapor deposition, it has poor adhesion. In order to solve this problem, in the present invention, (a) the crystal structure of the AlCr oxide upper layer has good consistency with the (111) plane of the crystal grains in the AlCrNO intermediate layer having a cubic (fcc) structure (006) AlCr oxide by forming a (006) -oriented AlCr oxide upper layer on the (Cr) (111) -oriented AlCr oxynitride intermediate layer, The upper layer was epitaxially grown on the AlCr oxynitride interlayer. Since there are many portions epitaxially grown from the intermediate layer in the upper layer, the upper layer has high adhesion to the intermediate layer, and the tool life is prolonged.

The degree of orientation of the (006) plane of the AlCr oxide upper layer is evaluated by the equivalent X-ray diffraction intensity ratio TC (006). The main crystal planes of the AlCr oxide crystal grains in the upper layer are (012) plane, (104) plane, (110) plane, (006) plane, (113) plane, (202) plane, (024) plane and ( 116) plane, the equivalent X-ray diffraction intensity ratio TC (006) representing the ratio of the (006) plane to all crystal planes is expressed by the following equation.
TC (006) = [I (006) / I ₀ (006)] / Σ [I (hkl) / 8I ₀ (hkl)]
(However, (hkl) is (012), (104), (110), (006), (113), (202), (024) and (116)).

I (hkl) is the measured X-ray diffraction intensity from the (hkl) plane of the upper layer, and I ₀ (hkl) is the standard X-ray diffraction intensity of α-type chromium oxide described in ASTM file number 381479. I ₀ (hkl) represents the X-ray diffraction intensity from the (hkl) plane of the isotropically oriented α-type chromium oxide powder particles. TC (006) indicates the relative intensity of the actually measured X-ray diffraction peak. The larger the TC (006), the stronger the X-ray diffraction peak intensity from the (006) plane. This indicates that the (006) plane is oriented perpendicular to the film thickness direction.

TC (006) is 1.3 or more, preferably 1.5 to 3, more preferably 1.8 to 2.5, and most preferably 2 to 2.3. The large TC (006) means that the AlCr oxide crystal grains are strongly oriented in the (006) plane (perpendicular to the substrate surface), that is, the AlCr oxide crystal grains are preferential in the [006] direction. It has grown to become vertically long fine crystal grains. The α-type (006) plane is perpendicular to the c-axis of the crystal lattice of the AlCr oxide. As a result, the lattice stripes on the (006) plane of the upper layer are continuously connected to the lattice stripes on the (111) plane of the intermediate layer and grow vertically. The upper layer made of AlCr oxide crystal grains grown in this way has a high density and excellent chipping resistance. When TC (006) is 1.8 or more, fine crystal grains are grown more vertically, so that adhesion and chipping resistance are very high. However, when TC (006) exceeds 2.5, the tool life tends to be shortened.

(3) Thickness In order to effectively exhibit the characteristics of the upper layer, the film thickness (Tu) of the upper layer is preferably 0.2 to 8 μm, more preferably 0.2 to 5 μm, most preferably 0.3 to 3 μm, and particularly preferably 0.3 to 2 μm. preferable. For high performance, the film thickness ratio (Tu / Tm) between the upper layer and the intermediate layer is preferably 1 or more, more preferably 1 to 100, most preferably 2 to 50, and particularly preferably 3 to 10. When the film thickness ratio (Tu / Tm) is less than 1 or more than 100, the adhesion between the intermediate layer and the upper layer is low.

[2] Film forming apparatus As a film forming apparatus for physical vapor deposition, an arc ion plating (AIP) apparatus, a filter-type arc ion plating apparatus, a sputtering apparatus, and the like are suitable. FIG. 1 shows an example of an AIP device 1 that can be used in the present invention. The AIP apparatus 1 includes a substrate holder 11, a lower layer forming source (target) 12 and its shutter 22, an intermediate layer forming source (target) 13 and its shutter 23, and an upper layer forming source (target). 14 and 15 and their

shutters

24 and 25, a reaction gas supply pipe 16, and a bias power source 17 for applying a bias voltage to the substrate. If the upper metal component is the same as that of the intermediate layer, the

sources

14 and 15 and their

shutters

24 and 25 may be omitted.

[3] Manufacturing method
(A) Formation of Lower Layer After cleaning the substrate, the shutter 22 of the source 12 is opened, and a lower layer is formed on the substrate at a temperature of 450 to 600 ° C. When the lower layer deposition temperature is less than 450 ° C., the adhesion is low, and when it exceeds 600 ° C., the heating effect is saturated.

The film formation atmosphere depends on the composition of the lower layer. When the lower layer is a nitride, a nitrogen atmosphere is used, and when the lower layer is a carbonitride, a mixed atmosphere of a hydrocarbon (acetylene, methane, etc.) gas and nitrogen gas is used. The flow rate of the atmospheric gas supplied during film formation is preferably 400-1500 ～ sccm. If it is less than 400 sccm, the formation of nitrides or carbonitrides is insufficient, and even if it exceeds 1500 cmsccm, the effect of the atmospheric gas is saturated. FIG. 2 shows an example of the flow rate of nitrogen gas supplied as a reaction gas. Point A indicates the time when the lower layer is formed, and point B indicates the time when the lower layer is completed.

The DC bias voltage applied to the substrate during the formation of the lower layer is preferably -400 V to -10 V. If the DC bias voltage is less than -400V, the residual stress is too large and the lower layer may peel off. If it exceeds -10V, no lower layer is formed. In the case of a pulse bias voltage, the frequency is preferably in the range of 0.1 to 300 kHz. If the frequency is less than 0.1 kHz, the lower layer is not formed, and if it exceeds 300 kHz, the effect of applying the pulse bias voltage is saturated.

(B) Formation of Intermediate Layer Shutter 22 of lower layer forming source 12 is closed and shutter 23 of intermediate layer forming source 13 is opened. The film forming temperature of the intermediate layer is preferably 450 to 580 ° C, more preferably 470 to 570 ° C. When the film forming temperature is less than 450 ° C., the residual stress of the intermediate layer is increased and the adhesion is lowered. When the film forming temperature exceeds 580 ° C., the residual stress is greatly reduced, and the hardness and mechanical strength of the film are reduced.

(1) Film formation atmosphere A mixed gas (reaction gas) of nitrogen gas and oxygen gas is used for the film formation atmosphere of the intermediate layer. The mixed gas may contain Ar gas. In this case, the proportion of Ar gas is preferably 70% by volume or less, more preferably 50% by volume or less of the mixed gas. The pressure in the film forming atmosphere is preferably 0.3 to 3 Pa, more preferably 0.5 to 2 Pa. When the film formation atmosphere pressure is outside the above range, it is difficult to form the intermediate layer.

(2) Reactant gas flow rate change In order to give the intermediate layer a gradient composition in which the oxygen concentration increases from the lower layer side to the upper layer side and the nitrogen concentration decreases from the lower layer side to the upper layer side, it is supplied during film formation of the intermediate layer While gradually increasing the flow rate of oxygen gas, the flow rate of nitrogen gas is gradually decreased. FIG. 2 shows an example of changes in the flow rates of oxygen gas and nitrogen gas for forming the intermediate layer. Point T ₁ indicates the time when the intermediate layer is formed, and point T ₂ indicates the time when the intermediate layer is completed.

In Fig. 2, the oxygen gas flow rate change pattern is represented by points E, F, and G. In order to suppress oxidation in the first half of the film formation process of the intermediate layer, the oxygen gas flow rate at the film formation start point E is preferably 100 sccm or less, more preferably 50 sccm or less, most preferably 10 sccm or less. It has been found that in order to obtain epitaxial growth from the intermediate layer to the upper layer, the oxygen gas flow rate at the time F of film formation needs to be 600 sccm or less. When the oxygen gas flow rate exceeds 600 sccm, many droplets are generated, and a hard film with excellent adhesion and smoothness cannot be obtained, and the upper layer is formed too early, resulting in epitaxial growth from the intermediate layer to the upper layer. Absent. The oxygen gas flow rate at the end of film formation F is preferably 600 sccm or less, and more preferably 300 to 500 sccm. Since the upper layer film formation starts simultaneously with the completion of the intermediate layer film formation, it is preferable that the oxygen gas flow rate at the end of the intermediate layer film formation reaches the oxygen gas flow rate for the upper layer film formation. It doesn't have to match. The difference between the oxygen gas flow rate at the end of forming the intermediate layer and the oxygen gas flow rate for forming the upper layer is preferably within 50 sccm, more preferably within 10 sccm.

Since the oxygen concentration distribution in the intermediate layer has a positive gradient (increases from the lower layer side to the upper layer side), the change in the flow rate of oxygen gas from point E to point F has a positive gradient. The average gradient of the oxygen gas flow rate during the period from point E to point F (T ₁ to T ₂ ) is preferably 20 to 400 sccm / min, more preferably 40 to 300 sccm / min, and most preferably 60 to 200 sccm / min. 80 to 150 sccm / min is particularly preferable. The oxygen gas flow rate is ideally increased linearly, but may be increased stepwise. If the average gradient of the oxygen gas flow is less than 20 sccm / min, the oxidation is insufficient, and if it exceeds 400 sccm / min, epitaxial growth cannot be obtained.

The nitrogen gas flow rate at the time point B at which the intermediate layer is formed is preferably 400-1500 sccm. The nitrogen gas flow rate at the upper layer deposition start point D is 0 sccm, but the nitrogen gas flow rate at the intermediate layer deposition end point C need not be completely 0 sccm, preferably 400 sccm or less, and 100 sccm The following is more preferable, and 50 sccm or less is most preferable. Since the nitrogen concentration distribution in the intermediate layer has a negative slope (decreases from the lower layer side to the upper layer side), the flow rate of nitrogen gas has a negative slope during the period from point B to point C (T ₁ to T ₂ ). Have. The nitrogen gas flow rate during the period (T ₁ to T ₂ ) has an average gradient of preferably −900 sccm / min to −30 sccm / min, more preferably −500 sccm / min to −60 sccm / min, and −300 sccm / min. Minutes to -80 sccm / min are most preferred, with -200 sccm / min to -100 sccm / min being particularly preferred. Ideally, the nitrogen gas flow rate decreases linearly, but it may decrease stepwise. If the average gradient of the nitrogen gas flow is less than −900 sccm / min, the nitrogen concentration gradient in the intermediate layer is too steep, and if it exceeds −30 sccm / min, a sufficient gradient composition cannot be obtained.

In FIG. 2, the film formation period (T ₁ to T ₂ ) of the intermediate layer is 5 minutes, but is not particularly limited. In order to sufficiently form the AlCr oxynitride intermediate layer, the film formation period (T ₁ to T ₂ ) is generally preferably 1 to 30 minutes, and more preferably 3 to 10 minutes.

(3) Bias voltage The bias voltage applied to the substrate during the formation of the intermediate layer is preferably -100 V to -50 V. If it is less than -100 V, the residual stress is too large, and if it exceeds -50 V, no intermediate layer is attached to the lower layer. When the energy of ions incident on the substrate is lowered to, for example, −90 V to −60 V, a smooth intermediate layer can be obtained. When a pulse bias voltage is used, the frequency is preferably 10 to 80 kHz in order to increase the adhesion of the intermediate layer. The pulse bias voltage is preferably a bipolar pulse in which the bias voltage has positive and negative amplitudes. A positive bias value between 5 and 10 V is sufficient.

(4) Arc current Since the intermediate layer contains low melting point Al, droplets are likely to be generated by rapid evaporation and abnormal ionization. In order to suppress this, it is preferable to keep the film-forming arc current as a discharge current in a low range of 100 to 150 A. If the arc current is less than 100 A, stable discharge cannot be maintained, and if it exceeds 150 A, a smooth intermediate layer cannot be obtained due to rapid evaporation of Al.

(C) Formation of the upper layer After the formation of the intermediate layer, the

shutters

24 and 25 of the upper

layer forming sources

14 and 15 are opened to form the upper layer. When the upper layer metal component is the same as that of the intermediate layer, the intermediate layer source 13 may be used as it is.

(1) Film formation temperature The film formation temperature of the upper layer is preferably 450 to 580 ° C, more preferably 470 to 570 ° C. If the film forming temperature is less than 450 ° C., the upper layer becomes amorphous, and if it exceeds 580 ° C., it is difficult to make TC (006) 1.3 or more.

(2) Film formation atmosphere Oxygen gas is used as a reaction gas for film formation on the upper layer. In order to prevent the droplets from reaching the substrate, the oxygen partial pressure in the film formation atmosphere is preferably 0.3 to 2 Pa, more preferably 0.4 to 1.8 Pa, most preferably 0.5 to 1.6 Pa, and particularly preferably 0.8 to 1.4 Pa. preferable. When the oxygen partial pressure is less than 0.3 Pa or more than 2 Pa, TC (006) of 1.3 or more cannot be obtained. When the film formation atmosphere contains Ar gas, the content of Ar gas is preferably 50% by volume or less, and more preferably 30% by volume or less of the film formation atmosphere.

(3) Oxygen gas flow rate The oxygen gas flow rate during upper layer deposition generally needs to be 100-600 sccm. If the oxygen gas flow rate is less than 100 sccm, the upper layer cannot be sufficiently formed, and if it exceeds 600 sccm, the upper layer is not densified, and epitaxial growth from the intermediate layer cannot be obtained. The oxygen gas flow rate during upper layer deposition is preferably 200 to 500 sccm, more preferably 250 to 500 sccm, and most preferably 300 to 450 sccm. In FIG. 2, the time between the upper layer deposition start point F and the upper layer deposition end point G is, for example, 60 minutes, but is not particularly limited. In order to sufficiently oxidize, the film formation time of the upper layer is preferably 30 to 100 minutes, more preferably 40 to 80 minutes.

(4) Bias voltage The bias voltage applied to the substrate during the upper layer deposition is preferably -100 V to -50 V, more preferably -90 V to -60 V. The generation of the upper layer is promoted by the bias voltage in this range, the crystal orientation of the α-type oxide layer becomes (006) dominant, and TC (006) becomes high. In addition, when using a pulse bias voltage, a bipolar pulse having a bias voltage with positive and negative amplitudes is preferable. The positive bias is preferably between 5 and 10V. The frequency of the pulse bias is preferably 10 to 80 kHz.

(5) Arc current Since the upper layer contains low melting point Al, droplets are likely to be generated due to rapid evaporation of Al and abnormal ionization. In order to suppress this, it is preferable to set the film-forming arc current as a discharge current as low as 100 to 150 A. If the arc current is less than 100 A, film formation is impossible. On the other hand, if it exceeds 150 A, rapid evaporation of Al is promoted, so that a smooth upper layer cannot be formed. By reducing the arc current value, an upper layer excellent in chipping resistance and chipping resistance can be obtained, which is oriented on a smooth (006) plane with few droplets [TC (006) is 1.3 or more].

The above film formation conditions promote the generation of α-type Al oxide rather than the formation of α-type Cr oxide, so the α-type crystal structure AlCr oxide constituting the upper layer is solidified with Cr in the α-type Al oxide. It is a melted solid solution. The AlCr-based oxide crystal grains having an α-type crystal structure are preferentially oriented in the (006) plane, the equivalent X-ray diffraction intensity ratio TC (006) is remarkably increased, and an upper layer having high smoothness can be obtained.

[4] Blade edge treatment The upper layer may be smoothed with a brush, buff, blast or the like in order to reduce the dropout of crystal grains in the upper layer and further enhance the adhesion. Further, on the upper layer, at least one metal element selected from the group consisting of periodic table IVa, Va, VIa group, Al and Si, and at least one nonmetallic element selected from C, N and O; You may form the hard protective film which makes this essential.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In each example and comparative example, the thickness of each layer was determined by measuring and averaging film thicknesses at arbitrary five locations in a 20,000-fold cross-sectional photograph of a scanning electron microscope (SEM). The composition at the center of the intermediate layer in the film thickness direction was defined as the average composition of the intermediate layer.

Example 1
(1) Formation of the lower layer A cemented carbide substrate (SNGA120408) for cutting tools containing 6.0% by mass of Co and 0.5% by mass of TaC and the balance WC and inevitable impurities is shown in FIG. A hard lower layer with a thickness of 3.0 μm having a composition (atomic ratio) of (Ti _0.5 Al _0.5 ) N on a substrate at 550 ° C. using a TiAl target and 1200 sccm of N ₂ gas. Formed.

(2) Formation of intermediate layer Using an AlCr target, with a film forming temperature of 550 ° C, a bias voltage of -60 V, and a pulse bias frequency of 20 kHz, the flow rate of N ₂ gas is 5 minutes as shown in Fig. 2. Gradually lower (substantially linearly) from 1200 sccm to 300 sccm, and gradually increase the O ₂ gas flow rate from 10 sccm to 500 sccm (substantially linearly) in 5 minutes (Al _0.27 Cr A hard oxynitride intermediate layer having a thickness of 0.5 μm and an average composition of _0.73 ) _0.38 (O _0.5 N _0.5 ) _0.62 (atomic ratio) was formed. The atmospheric pressure (oxygen partial pressure) at the time point B when the intermediate layer was formed was 3.0 Pa.

(3) Formation of the upper layer Using an AlCr target continuously from the formation of the intermediate layer, the flow rate of O ₂ gas was set to 500 sccm under the conditions of film formation temperature 550 ° C, bias voltage -60 V, and pulse frequency 20 kHz. The hard oxide upper layer having a composition of (Al _0.27 Cr _0.73 ) _1.9 O _3.1 (atomic ratio) and having a thickness of 2.0 μm was formed for about 1 hour. The atmospheric pressure (oxygen partial pressure) at the time of forming the upper layer was 1.2 Pa.

(4) Analysis of the crystal structure of the upper layer To identify the crystal structure of the upper layer of the hard-coated tool obtained, an X-ray diffractometer (RU-200BH) manufactured by Rigaku Corporation was used under the following conditions. Line diffraction measurement was performed. The X-ray diffraction pattern of the upper layer is shown in FIG.
X-ray source: CuKα1 ray (wavelength λ: 0.15405 nm)
Tube voltage: 120 kV
Tube current: 40 mA
X-ray incident angle: 5 °
X-ray entrance slit: 0.4 mm
2θ: 20 to 70 °.

In the X-ray diffraction pattern of the upper layer shown in FIG. 3, the peaks of the (012) plane, (104) plane, (110) plane, (006) plane, (113) plane, (024) plane and (116) plane are shown. There was no peak on the (202) plane. Since the (012) plane has one peak, it can be seen that the α-type aluminum oxide peak and the α-type chromium oxide peak are not separated. Table 1 shows the measured distance d between the upper surfaces obtained from the X-ray diffraction pattern of FIG. Tables 2 and 3 show the inter-plane distance d and standard X-ray diffraction intensities I ₀ and 2θ of α-type aluminum oxide (ASTM file number 100173) and α-type chromium oxide (ASTM file number 381479), respectively. From the measured value of the inter-surface distance d, it can be seen that the composition of the upper layer is closer to α-type chromium oxide than α-type aluminum oxide.

Using the following equivalent X-ray diffraction intensity ratio TC (006), the degree of orientation of the upper (006) plane was quantified.
TC (006) = [I (006) / I ₀ (006)] / Σ [I (hkl) / 8I ₀ (hkl)]
(However, (hkl) is (012), (104), (110), (006), (113), (202), (024) and (116), and I ₀ (hkl) is α-type oxidation) This is the standard X-ray diffraction intensity of chromium.) As a result, the TC (006) of the upper layer of Example 1 was 2.08.

(5) Composition analysis Using an electron probe microanalyzer (EPMA, JXA-8500F manufactured by JEOL Ltd.), in the thickness direction of the intermediate layer under the conditions of acceleration voltage 10 kV, irradiation current 1.0 uA and probe diameter 0.01 μm The composition at the center was measured and taken as the average composition. The average composition of the intermediate layer was 10.4 atomic percent Al, 27.9 atomic percent Cr, 31.9 atomic percent N and 29.8 atomic percent O. The composition of the upper layer was 10.1 atomic% Al, 27.9 atomic% Cr and 62.0 atomic% O. As a result of X-ray diffraction, it was found that the upper layer had an α-type crystal structure.

(6) Measurement of oxygen concentration gradient and nitrogen concentration gradient in the intermediate layer Using an electron energy loss spectrometer (EELS, ENFINA1000 manufactured by Gatan) with an electron beam diameter of 0.1 nm, the interface between the intermediate layer and the lower layer and the intermediate layer The concentration distribution of oxygen and nitrogen in the thickness direction region including the interface between the layer and the upper layer was measured. The measurement results are shown in FIG. The oxygen concentration increased substantially linearly from the lower layer side to the upper layer side, and the nitrogen concentration decreased substantially linearly from the lower layer side to the upper layer side. The average gradient was determined from the plots of oxygen concentration and nitrogen concentration by the method of least squares.

(7) Analysis of epitaxial growth The region including the interface between the intermediate layer and the upper layer was observed with a transmission electron microscope (TEM). A TEM photograph (2 million times) is shown in FIG. 5 (a), and a schematic diagram of the TEM photograph is shown in FIG. 5 (b). As is clear from FIG. 5 (a), in at least a part of the interface region between the intermediate layer and the upper layer, the crystal lattice stripes in the intermediate layer and the crystal lattice stripes in the upper layer are continuous, and epitaxial growth was observed.

(8) Measurement of tool life After performing a cutting test on a hard-coated tool under the following conditions, observe the cutting edge of the tool with an optical microscope with a magnification of 100 times, and wait for the upper layer of the cutting edge to peel or chip. The tool life was determined. The peeling of the upper layer was judged by surface analysis with EPMA.
Work material: FC250 (square)
Cutting method: Intermittent turning Tool shape: SNGA120408
Cutting speed: 300 m / min Feed: 0.25 mm / rev
Cut depth: 1.0 mm
Cutting fluid: None (dry machining)

Examples 2-7
In order to investigate the effect of the content of Al and Cr in the upper layer, a hard film coated tool was prepared in the same manner as in Example 1 except that an AlCr target having a different composition was used for the upper layer, and the same measurement as in Example 1 was performed. Went.

Examples 8-13
In order to investigate the influence of the N and O contents in the intermediate layer, a hard film coated tool was prepared in the same manner as in Example 1 except that the flow rates of N ₂ gas and O ₂ gas were changed. Measurements were made. FIG. 6 shows changes in the flow rates of oxygen gas and nitrogen gas during intermediate layer deposition in Example 9. As is apparent from FIG. 6, in order to obtain an oxygen gas flow rate gradient of 90 sccm / min, the oxygen gas flow rate is set to 50 sccm at the intermediate layer deposition start time E, and is set to 500 sccm at the intermediate layer deposition end time F. In order to obtain a nitrogen gas flow rate gradient of −90 sccm / min, the nitrogen gas flow rate was set to 500 sccm at the intermediate layer deposition start point B and 50 sccm at the intermediate layer deposition end point C. Table 4 shows the gas flow rates of Examples 8 to 13.

Examples 14-19
In order to investigate the influence of the content of Al and Cr in the intermediate layer, a hard film coated tool was prepared in the same manner as in Example 1 except that the composition of the AlCr target used for film formation of the intermediate layer was changed. The same measurement was performed.

Examples 20-42
Hard film coating in the same manner as in Example 1 except that the composition of the AlCr target for forming the intermediate layer was changed to change the composition of the intermediate layer (Al _s Cr _t ) _a (N _v O _w ) _b . A tool was prepared and the same measurement as in Example 1 was performed.

Example 22
The oxygen gas flow rate and the nitrogen gas flow rate at the start of the intermediate layer deposition are set to 0 sccm and 1000 sccm, respectively, the oxygen gas flow rate and the nitrogen gas flow at the end of the intermediate layer deposition are set to 500 sccm and 200 sccm, respectively, and the bias voltage is − A hard film-coated tool was produced in the same manner as in Example 1 with 100 V and an intermediate layer deposition time of 10 minutes, and the same measurement as in Example 1 was performed. The thickness of the intermediate layer in the obtained hard film-coated tool was 1.0 μm.

Comparative Example 1
As shown in FIG. 7, a hard film coated tool was prepared in the same manner as in Example 1 except that the oxygen gas flow rate and the nitrogen gas flow rate were kept constant at 500 sccm in the intermediate layer deposition step, respectively. Measurements were made. The concentration distribution of oxygen and nitrogen in the thickness direction region including the interface between the intermediate layer and the lower layer and the interface between the intermediate layer and the upper layer was measured by the EELS method. The measurement results are shown in FIG. The oxygen concentration was substantially the same from the lower layer side to the upper layer side.

Comparative Example 2
On the same substrate as Example 1, a Ti (CN) lower layer, Ti (NO) intermediate layer and α-type Al ₂ O ₃ layer were formed by chemical vapor deposition to produce a hard film-coated tool. The same measurement was performed.

Table 5 shows the film formation method of each example and comparative example, the type and thickness of the lower layer and the intermediate layer, and whether or not O is continuously increased. Table 6 shows the composition of the intermediate layer. Table 7 shows the conditions and gradient composition, Table 8 shows the composition of the upper layer, Table 9 shows the film formation method, type, thickness, crystal structure and equivalent X-ray diffraction intensity ratio TC (006), and tool life of the upper layer. Shown in However, in Table 9, the above composition is abbreviated as (AlCr) ₂ O ₃ .

Table 7 (continued)

Examples 23-28, Comparative Examples 3 and 4
A hard film coated tool was produced in the same manner as in Example 1 except that the upper layer deposition temperature was changed as shown in Table 10, and the upper layer crystal structure, TC (006), and tool life were measured. The measurement results are shown in Table 10 together with the film formation temperature.

Examples 29-33, Comparative Examples 5 and 6
A hard film coated tool was prepared in the same manner as in Example 1 except that the bias voltage at the time of forming the upper layer was changed as shown in Table 11, and the crystal structure of the upper layer, TC (006), and the tool life were measured. The measurement results are shown in Table 11 together with the bias voltage.

Examples 34-36, Comparative Examples 7 and 8
A hard film-coated tool was prepared in the same manner as in Example 1 except that the atmospheric pressure (partial pressure of oxygen gas) at the time of forming the upper layer was changed as shown in Table 12, and the upper layer crystal structure and TC (006), and Tool life was measured. The measurement results are shown in Table 12 together with the atmospheric pressure.

Examples 37-40, Comparative Examples 9 and 10
A hard film coated tool was prepared in the same manner as in Example 1 except that the flow rate of the oxygen gas for forming the upper layer was changed as shown in Table 13, and the upper layer crystal structure and TC (006) were measured. . The measurement results are shown in Table 13 together with the flow rate of oxygen gas. As is apparent from Table 13, a large TC (006) and a long tool life were obtained when the flow rate of oxygen gas was in the range of 300 to 500 sccm. In particular, since the tool life was long when the flow rate of oxygen gas was in the range of 300 to 400 sccm, the surface roughness of the upper layer was measured to investigate the cause. For the measurement of surface roughness, use a roughness measuring instrument (Surfcoder SE-30D) manufactured by Kosaka Laboratories with a diamond stylus with a radius of curvature of 5 μm, and measure any five locations in the upper layer. Averaged. As a result, in Examples 39 and 40 where the flow rate of oxygen gas was 300 sccm and 400 sccm, the average surface roughness Ra of the upper layer was 0.4 μm, and in Example 1 where the flow rate of oxygen gas was 500 sccm, the average of the upper layer The surface roughness Ra was 0.5 μm. Since the main cause of the surface roughness of the upper layer is droplets, it has been found that the generation of droplets is small when the flow rate of oxygen gas is in the range of 300 to 500 sccm, particularly in the range of 300 to 400 sccm.

Fig. 9 shows the relationship between the TC (006) and the life of the hard-coated tools in the examples and comparative examples. In the figure, black circles (●) are examples, and white triangles (Δ) are comparative examples. The lifetimes of the hard film-coated tools of Examples 1 to 61 were all 4 minutes or longer, which was about twice as long as that of Comparative Examples 1 to 14. This is because the upper layer that is strongly oriented in the (006) plane is formed of fine AlCr oxide crystal grains, has little dropout of crystal grains, has high adhesion, and is excellent in chipping resistance. . When TC (006) was 1.8 to 2.5, a very long tool life was obtained. In particular, in the range of TC (006) from 2 to 2.3, the life of most tools was more than 10 minutes.

Examples 41-46, Comparative Examples 11 and 12
A hard film-coated tool was prepared in the same manner as in Example 1 except that the thickness of the intermediate layer and the upper layer were changed by changing the film formation time of the intermediate layer or the upper layer, and the upper layer crystal structure and TC (006 ) And tool life. The results are shown in Table 14. Although the composition of the upper layer is abbreviated as (AlCr) ₂ O ₃ , it is strictly (Al _0.27 Cr _0.73 ) _1.9 O _3.1 .

The hard film-coated tools of Examples 41 to 46, each having an intermediate layer thickness (Tm) of 0.1 to 5 μm and an upper layer thickness (Tu) of 0.3 to 6 μm, had a long life. However, the hard film coated tool of Example 46 in which Tm> Tu had a shorter life than the hard film coated tools of Examples 41 to 45 satisfying Tm ≦ Tu. The hard film coated tool of Comparative Example 11 had a short life due to wear because the upper layer was as thin as 0.02 μm. In the hard film-coated tool of Comparative Example 12, the intermediate layer was as thin as 0.04 μm, so peeling occurred between the intermediate layer and the upper layer, and the life was short.

Examples 47-57
A hard film-coated tool was produced in the same manner as in Example 1 except that the target and reaction gas used for forming the lower layer were changed as shown in Table 15. The flow rate of the reaction gas used for forming the lower layer was in the range of 100-1500 sccm. In Examples 52-57, the flow rate of acetylene gas was 100 sccm, and the flow rate of nitrogen gas was 500 sccm. The life of each hard film coated tool and the TC (006) of the upper layer were measured in the same manner as in Example 1. The results are shown in Table 15. All of the hard film coated tools of Examples 47 to 57 had a sufficiently longer life than the hard film coated tool of the comparative example, even if the type of the lower layer was changed.

Examples 58-62, Comparative Examples 13 and 14
A hard film-coated tool was produced in the same manner as in Example 1 except that the film formation time of the lower layer was changed to change the film thickness of the lower layer, and the TC (006) and tool life of the upper layer were measured. The results are shown in Table 16. Table 16 shows that the tool life is long when the thickness of the lower layer is 0.5 to 10 μm.

Claims

A hard coating tool in which a hard lower layer, an intermediate layer, and an upper layer are formed on a substrate by physical vapor deposition,
(a) the lower layer is at least one metal element selected from the group consisting of elements IVa, Va and VIa of the periodic table, Al and Si, and at least selected from the group consisting of N, C and B Containing a kind of non-metallic element,
(b) The upper layer has the general formula: (Al x Cr y ) c O d (where x and y are numbers representing the atomic ratio of Al and Cr, and c and d represent the atomic ratio of AlCr and O) And a composition represented by the following condition: x = 0.1 to 0.4, x + y = 1, c = 1.86 to 2.14, and d = 2.79 to 3.21) TC (006) has an α-type crystal structure of 1.3 or more,
(c) The intermediate layer is made of an oxynitride essentially containing Al and Cr as metal elements, and the oxygen concentration increases from the lower layer side to the upper layer side and the nitrogen concentration decreases from the lower layer side to the upper layer side. The average composition is a general formula: (Al s Cr t ) a (N v O w ) b (where s, t, v, and w are atomic ratios of Al, Cr, N, and O, respectively) A and b are numbers representing the atomic ratio of AlCr and NO, and the following conditions:
s = 0.1-0.4,
s + t = 1,
v = 0.1-0.8,
v + w = 1,
a = 0.3-0.5, and
a + b = 1 is satisfied. The hard-coated tool characterized by the above-mentioned.
2. The hard film coated tool according to claim 1, wherein the crystal lattice fringes of the intermediate layer and the crystal lattice fringes of the upper layer are at least partially continuous at the interface between them.
3. The hard film coated tool according to claim 1, wherein the thickness (Tm) of the intermediate layer is 0.1 to 5 μm, the thickness (Tu) of the upper layer is 0.2 to 8 μm, and Tm ≦ Tu. Hard film coated tool characterized by satisfying
4. The hard film-coated tool according to claim 1, wherein the lower layer has a thickness of 0.5 to 10 μm.
5. The hard film coated tool according to claim 1, wherein an average gradient of oxygen concentration in the gradient composition of the intermediate layer from the lower layer side to the upper layer side is 10 to 600 atomic% / μm. Hard film coated tool characterized by
6. The hard film coated tool according to claim 1, wherein an average gradient of nitrogen concentration in the gradient composition of the intermediate layer from the lower layer side to the upper layer side is −650 to −10 atomic% / μm. A hard-coated tool characterized by being.
A hard-coated tool having a hard lower layer, an intermediate layer and an upper layer formed by physical vapor deposition on a substrate, wherein: (a) the lower layer is an element of groups IVa, Va and VIa of the periodic table, Al and Si At least one metal element selected from the group consisting of and at least one non-metal element selected from the group consisting of N, C and B, and (b) the upper layer has the general formula: (Al x Cr y ) c O d (where x and y are numbers representing the atomic ratio of Al and Cr, c and d are numbers representing the atomic ratio of AlCr and O, and x = 0.1 to 0.4, x + y = 1 C = 1.86-2.14, and d = 2.79-3.21), and an α-type crystal structure having an equivalent X-ray diffraction intensity ratio TC (006) of 1.3 or more. And (c) the intermediate layer is made of an oxynitride essentially containing Al and Cr as metal elements, and the oxygen concentration increases from the lower layer side to the upper layer side. Nitrogen concentration has a gradient composition that decreases toward the upper side from the lower side, the average composition formula to: (Al s Cr t) a (N v O w) b ( However, s, t, v and w is a number representing the atomic ratio of Al, Cr, N and O, a and b are numbers representing the atomic ratio of AlCr and NO, s = 0.1 to 0.4, s + t = 1, v = 0.1 to 0.8 V + w = 1, a = 0.3 to 0.5, and a + b = 1.)
(1) While increasing the flow rate of oxygen gas supplied as a reaction gas from the start to the end of the formation of the intermediate layer to 600 sccm or less, decrease the flow rate of nitrogen gas,
(2) The method is characterized in that the flow rate of oxygen gas during the formation of the upper layer is set to 100 to 600 sccm, and the oxygen partial pressure in the film formation atmosphere is controlled to 0.3 to 2 Pa.
8. The method for producing a hard film-coated tool according to claim 7, wherein a flow rate of oxygen gas during the upper layer film formation is controlled to 300 to 500 sccm.
9. The method for manufacturing a hard film-coated tool according to claim 7, wherein the upper layer oxygen gas flow rate is reached at the end of film formation of the intermediate layer.