JP5660457B2 - Hard film coated mold - Google Patents

Description

The present invention is configured by coating a lower layer of an AlCr oxynitride of a hard film and an upper layer of an AlCr oxide on a mold base by a physical vapor deposition method, the upper layer is smooth, and the lower layer and the upper layer The present invention relates to a new and high-performance hard film coated mold excellent in adhesiveness, heat resistance and sliding characteristics .

  Coatings such as CrN and TiN have been used for sliding members and molds, but diamond-like carbon (DLC) has become widespread in recent years. This is because it is easy to obtain a smooth surface and is excellent in frictional properties, so that it is useful as a coating on a sliding member or the like. However, since it is difficult to improve the sliding properties with iron-based materials with carbon-based coatings, and there are limitations on the application fields, research and development of coating coatings with excellent sliding properties to replace such CrN and TiN have been conducted. Has been done.

Patent Document 1 discloses a workpiece in which a hard layer substantially made of (Al, Cr) ₂ O ₃ crystal having a chromium content of more than 5 atomic% is formed. In this document, a crystalline hard layer having the above-mentioned composition that can be obtained only by a high-temperature CVD method has been obtained at a film forming temperature of less than 1000 ° C. by a very simple measure of adding chromium to aluminum.

Patent Document 2 discloses a multi-layer coating system in which a (Al _0.5 Cr _0.5 ) ₂ O ₃ coating having a corundum type structure is coated on an AlCrON hard coating (Nos. 93 and 95 in Table 6). See).

  Patent Document 3 discloses a technique related to a coating mold in which a hard coating of AlCr oxynitride is coated.

  Patent Document 4 discloses a technology related to a die casting coating die coated with an AlCr oxide.

Japanese Patent No. 3323534 Special table 2010-506049 gazette Japanese Patent No. 4471580 JP 2010-58135 A

  According to the study of the present inventor, the AlCr oxide film of Patent Document 1 by physical vapor deposition has an equivalent X-ray diffraction intensity ratio TC (110) of less than 1.3. It was found that film peeling occurred. That is, the AlCr oxide crystal grains constituting the AlCr oxide film of Patent Document 1 are liable to fall off, and there is a problem that seizure and galling are likely to occur in mold applications.

In paragraph 61 of Patent Document 2, the introduction of oxygen starts 5 minutes after turning on the AlCr (50/50) target. The oxygen is set to 50 sccm to 1000 sccm within 10 minutes. At the same time, the TiAl (50/50) target is turned off and nitrogen (N ₂ ) is returned to about 100 sccm. ” Further, Table 7 discloses specific oxygen (O ₂ ) gas flow rate and nitrogen (N ₂ ) gas flow rate during film formation.
However, according to the tracing experiment (Comparative Example 9 described later) by the present inventor, it was difficult to form the AlCr oxynitride layer (hard layer) according to the present invention.

  As for the usage status of molds, usage methods that take environmental loads into consideration are also being promoted, and there are attempts to reduce the use of mold release materials and to eliminate the use itself. Therefore, the occurrence of damage or peeling of the film due to seizure, galling or the like is also a problem. Therefore, a film used for a mold is required to have excellent adhesion, seizure resistance, and galling resistance in addition to wear resistance.

  Patent Document 3 discloses only an AlCr oxynitride film containing Al and Cr as essential constituent elements, and an AlCr oxide film having a TC (110) of 1.3 or more is further coated thereon by so-called epitaxial growth. It was n’t.

  Patent Document 4 discloses that a laminated structure of Cr oxide and AlCr oxide can easily form an oxide having a corundum structure and improve wear resistance and seizure resistance. . That is, the upper layer of AlCr oxide is not coated by so-called epitaxial growth on the lower layer of AlCr oxynitride.

The present invention aims to solve the above-mentioned conventional problems, and is a new and high-performance hard coating having a smooth upper layer surface, excellent wear resistance, a low friction coefficient, excellent sliding characteristics, and excellent adhesion. A coated mold is provided .

The hard coating coated mold of the present invention is a hard coating formed on a substrate by physical vapor deposition,
The hard coating has a lower layer and an upper layer formed on the lower layer,
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 are numbers representing the atomic ratio of AlCr and O) X = 0.1 to 0.6, x + y = 1, c = 1.86 to 2.14, and d = 2.79 to 3.21) and an α-type crystal structure, and an equivalent X-ray diffraction intensity ratio TC (110) is made of oxide with 1.3 or more,
The lower layer is made of an oxynitride essentially containing Al and Cr as metal elements, and 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. And the average composition is represented by the general formula: (Al _s Cr _t ) _a (N _v O _w ) _b (where s and t are numbers representing the atomic ratio of Al and Cr, and v and w are N and O A and b are numbers representing the atomic ratio of AlCr and NO, and the following conditions:
s = 0.1-0.6,
s + t = 1,
v = 0.1-0.8,
v + w = 1,
a = 0.35-0.6,
And a + b = 1. )
The lower layer crystal lattice fringe and the upper layer crystal lattice fringe are at least partially continuous at the interface between them .
The hard film-coated mold of the present invention having such characteristics has higher performance than the conventional one.

The upper layer than the size Ikoto preferably equivalent X-ray diffraction intensity ratio TC (110) is equivalent X-ray diffraction intensity ratio TC (104). Furthermore, the upper layer has a surface roughness Ra is preferably der Rukoto below 0.2 [mu] m.

Thick (Tl) is 0.1~4μm of the lower layer, the thickness of the upper layer (Tu) in 0.2～8Myuemu, preferably satisfy the relationship Tl ≦ Tu.

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

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

The upper layer of AlCr oxide by physical vapor deposition was epitaxially grown on the lower layer of AlCr oxynitride by physical vapor deposition, and the crystal orientation of the upper AlCr oxide crystal grains: TC (110) was controlled to be 1.3 or higher. Thus, it is possible to provide a hard film-coated mold with significantly higher performance than the conventional AlCr oxide film-coated mold by physical vapor deposition.

It is the schematic which shows an example of the AIP apparatus which can be used for this invention. 6 is a graph showing changes in flow rates of oxygen gas, nitrogen gas, and Ar gas in the lower layer and upper layer film forming steps 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 a lower layer of Example 1. FIG. 2 is a schematic diagram showing an interface region between a lower layer and an upper layer in the hard film-coated mold of Example 1. FIG. 2 is a scanning electron micrograph showing the upper layer surface of Example 1. FIG. 6 is a scanning electron micrograph showing the upper layer surface of Comparative Example 6. 10 is a graph showing changes in flow rates of oxygen gas, nitrogen gas, and Ar gas in the lower layer and upper layer film forming steps in Example 6. FIG. 14 is a graph showing changes in flow rates of oxygen gas, nitrogen gas, and Ar gas in the lower layer and upper layer film forming steps in Example 12. 10 is a graph showing an oxygen concentration distribution and a nitrogen concentration distribution in a lower layer of Example 12. In the lower layer and the upper layer of the film forming process that put in Comparative Example 7 is a graph showing a change in flow rate of the oxygen gas and nitrogen gas. 10 is a graph showing an oxygen concentration distribution and a nitrogen concentration distribution in a lower layer of Comparative Example 7. 10 is a graph showing changes in flow rates of oxygen gas and nitrogen gas in the lower layer and upper layer film forming steps in Comparative Example 9. It is a graph which shows the relationship between TC (110) of the hard film coating metal mold | die of an Example and a comparative example, and a metal mold | die lifetime. It is a schematic diagram which shows one Example of the hard film coating metal mold | die of this invention used for the measurement of a metal mold | die lifetime.

[1] Hard coating coated mold (A) substrate As a substrate material for the hard coating coated mold of the present invention, cemented carbide, cubic boron nitride (CBN), high speed steel, mold steel, cermet, ceramics, etc. Cemented carbide is particularly preferable.

(B) Lower layer (1) Average composition The lower layer formed on a base body 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 lower layer is represented by the general formula: (Al _s Cr _t ) _a (N _v O _w ) _b (where s and t are numbers representing the atomic ratio of Al and Cr, and v and w are N and O A number representing the atomic ratio, a and b are numbers representing the atomic ratio of AlCr and NO, respectively,
s = 0.1-0.6,
s + t = 1,
v = 0.1-0.8,
v + w = 1,
a = 0.35-0.6,
And a + b = 1. ).
As the average composition, the composition at the center in the thickness direction of the lower layer can be used. With this composition, the lower layer has an fcc structure oriented in the (111) plane and has high adhesion to the upper layer.

  The sum (s + t) of the atomic ratio s of Al and the atomic ratio t of Cr is 1. s is 0.1 to 0.6, preferably 0.15 to 0.58, and most preferably 0.2 to 0.5. t is 0.9 to 0.4, preferably 0.85 to 0.42, and most preferably 0.8 to 0.5. When s is less than 0.1, the content of Cr in the lower layer is excessive, the hardness and mechanical strength of the lower layer are low, and the adhesion between the substrate and the upper layer is low. On the other hand, when s exceeds 0.6, the content of Al in the lower layer is excessive, and since it has a hexagonal crystal structure, the hardness and mechanical strength of the lower layer are also low, and the adhesion between the substrate and the upper layer is low.

  The sum (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 lower layer is oriented so that the (111) plane appears on the surface, and the crystal lattice pattern of the upper layer is the crystal lattice pattern of the AlCr oxide. Therefore, the adhesion between the lower layer and the upper layer is high. When v is less than 0.1, the lower layer is not only brittle due to excess oxygen, but also has poor adhesion to the upper layer. On the other hand, when v is more than 0.8, the lattice constant of the lower 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 0.35 to 0.6, preferably 0.38 to 0.57, and most preferably 0.4 to 0.55. b is 0.65 to 0.4, preferably 0.62 to 0.43, and most preferably 0.6 to 0.45. When a is less than 0.35, the metal component (Al, Cr) in the lower layer is too small, and the hardness is insufficient. When a is more than 0.6, there are too many metal components, a lower layer with a uniform balance between the metal component and the nonmetal component cannot be obtained, and the mechanical strength is inferior.

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

  As shown in FIG. 4, the oxygen concentration and nitrogen concentration in the lower layer preferably change substantially linearly. In this case, since the lattice constant of the lower 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 lower 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 substrate side to the upper layer side. If the nitrogen concentration is reduced, a sudden change in residual stress is suppressed, and delamination is suppressed.

  In the gradient composition of the lower layer, the average gradient of the 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. In particular, 60 to 150 atomic% / μm is most preferable. Since the average gradient of oxygen concentration becomes smaller as the lower layer becomes thicker, if the average gradient of oxygen concentration is less than 10 atomic% / μm, the lower layer becomes too thick, and the chipping resistance of the hard coating is reduced. If the average gradient of the oxygen concentration is more than 600 atomic% / μm, the oxygen concentration change is abrupt, and the meaning of providing the lower layer of the 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 substrate 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 lower layer will be too thick, and the chipping resistance of the hard coating will be lowered. Further, when the absolute value of the average gradient of nitrogen concentration is more than 650 atomic% / μm, the nitrogen concentration change is abrupt and the meaning of providing the lower layer of the 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 substrate and the upper layer, the lower layer thickness (Tl) is preferably 0.1 to 4 μm, more preferably 0.2 to 3.5 μm, 0.3-3 μm is most preferable, and 0.4-2.5 μm is particularly preferable.

(C) Upper layer (1) Composition The upper layer formed on a lower layer by a physical vapor deposition method is a hard film | membrane of the oxide which essentially requires Al and Cr as a metal element. The composition of 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 are numbers representing the atomic ratio of AlCr and O) And x = 0.1 to 0.6, 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 0.6, preferably 0.15 to 0.6, and more preferably 0.2 to 0.6. y is 0.9 to 0.4, preferably 0.85 to 0.4, and more preferably 0.8 to 0.4. The upper layer has an α-type crystal structure with x of 0.1 to 0.6. When x is less than 0.1, Cr is excessive, and the hardness and mechanical strength of the upper layer are low and the adhesion to the lower layer is inferior, and the heat resistance is also inferior because Cr ₂ O ₃ is excessive. When x exceeds 0.6, 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 are formed as droplets in the upper layer or on the surface. Present, the layer density decreases, and the adhesion and chipping resistance deteriorate.

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 centered on 2 and 3, specifically, c is 1.86 to 2.14, preferably 1.9 to 2.1, more preferably Is 1.93 to 2.06, most preferably 1.94 to 2.06. 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
In the case where the upper layer of the oxide has a crystal form other than α-type such as γ-type, κ-type, or δ-type, it transforms into α-type at a high temperature and shrinks that cannot be practically used. 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, when the upper layer of the oxide has a crystal form other than the α type, it is peeled off or chipped from the lower layer. In contrast, the hard film-coated mold of the present invention has an upper layer of a smooth surface having an α-type crystal structure, and has excellent adhesion resistance and fracture resistance, as well as excellent adhesion to the lower layer. .

  Since the AlCr oxide formed by the physical vapor deposition method has a lower density than the AlCr oxide formed by the chemical vapor deposition method, the adhesion was inferior. 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 lower layer having a cubic (fcc) structure (110) The upper layer of the AlCr oxide is formed by forming an upper layer of the AlCr oxide oriented in the (110) plane on the lower layer of the AlCr oxynitride oriented in the (b) (111) plane. Epitaxial growth was performed on the AlCr oxynitride lower layer. Since there are many portions epitaxially grown from the lower layer in the upper layer, the upper layer has high adhesion to the lower layer, and the mold life is prolonged.

The degree of orientation of the (110) plane of the upper layer, which is an AlCr oxide , is evaluated by the equivalent X-ray diffraction intensity ratio TC (110) of α-type AlCr oxide crystal grains. Similarly the upper layer of the (104) plane orientation degree of a AlCr oxide is more evaluated α type AlCr oxide grains equivalent X-ray diffraction intensity ratio TC (104). The main crystal planes of α-type AlCr oxide crystal grains in the upper layer are (012) plane, (104) plane, (110) plane , (113) plane, (202) plane, (024) plane and (116) plane. Therefore, the equivalent X-ray diffraction intensity ratios TC (110) and TC (104) representing the ratio of the (110) plane and the (104) plane with respect to all crystal planes are expressed by the following equations.
TC (110) = [I (110) / I ₀ (110)] / Σ [I (hkl) / 8I ₀ (hkl)]
TC (104) = [I (104) / I ₀ (104)] / Σ [I (hkl) / 8I ₀ (hkl) ]
( However, (hkl) is (012), (104), (110) , (113) , (202), (024) and (116).)

I (hkl) is an actually measured X-ray diffraction intensity from the (hkl) plane of the upper layer, and I ₀ (hkl) is a standard X-ray diffraction intensity of α-type chromium oxide described in ASTM file number 382479. I ₀ (hkl) represents the X-ray diffraction intensity from the (hkl) plane of the isotropically oriented α-type chromium oxide powder particles. TC (110) indicates the relative intensity of the actually measured X-ray diffraction peak. The larger the TC (110), the stronger the X-ray diffraction peak intensity from the (110) plane. This indicates that the (110) plane is oriented parallel to the film thickness direction.

In the present invention, TC (110) is Ru der 1.3 or more. TC (110) is preferably 1.4 to 3.6, more preferably 1.5 to 3.6, and still more preferably 1.8 to 3.6. The large TC (110) means that the AlCr oxide crystal grains are strongly oriented in the (110) plane (parallel to the substrate surface), that is, the AlCr oxide crystal grains are preferential in the [110] direction. It has grown to become vertically long fine crystal grains. The upper layer made of the AlCr oxide crystal grains grown in this way has a high density and is excellent in the adhesion resistance, fracture resistance and adhesion to the lower layer of the AlCr oxide crystal grains. Since such upper surface irregularities of AlCr oxide crystal grains grown is suppressed smaller than conventional average surface roughness Ra of the upper layer is preferably Ri Do and 0.2μm or less. When TC (110) is 1.8 or more, fine crystal grains grow longer in length, so that the adhesion and the AlCr oxide crystal grain drop-off suppressing effect are very high. However, when TC (110) exceeds 3.6, the mold life tends to be shortened.

In the present invention , the upper layer further satisfies the relationship of TC (110)> TC (104). When TC (110) > TC (104), the effect of suppressing the drop-out of the upper crystal grains becomes more remarkable.

  The smoothing mechanism of the upper crystal grains is considered as follows. In general, in the AlCr oxide hard film formed by physical vapor deposition, the surface of the AlCr oxide crystal grains has large irregularities, but in the present invention, the AlCr oxide crystal grains grow perpendicular to the substrate (c-axis direction). Instead of growing in parallel, the unevenness of the AlCr oxide crystal grain surface is remarkably reduced. The present invention utilizes this principle. That is, in the hard coating coated mold of the present invention, the (110) plane of the α-type AlCr oxide crystal grains grows in the [110] direction parallel to the substrate (c plane). The surface of the crystal grain is very smooth, and the smoothing effect suppresses dropping of the AlCr oxide crystal grain. The (104) plane and (116) plane are inclined by 38.3 ° and 42.3 ° with respect to the c-axis, respectively, and the smoothing effect is smaller than that of the (110) plane.

(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 higher performance, the film thickness ratio (Tu / Tl ) between the upper layer and the lower 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 / Tl ) is less than 1 or more than 100, the adhesion between the lower layer and the upper layer is low.

(4) Surface roughness (Ra)
The surface roughness (Ra) of the upper layer uses a diamond stylus with a radius of curvature of 5 μm, and the surface roughness measuring instrument (trade name: Surfcorder SE-30D, manufactured by Kosaka Laboratory Ltd.) The surface roughness (Ra) is measured along the five line segments (5 mm in length) and averaged.

(5) Surface area ratio of droplets (%)
The area occupied by the droplets on the upper layer surface is an arbitrary five field of view of 50 μm × 50 μm in the scanning electron microscope (SEM) photograph of the upper layer surface taken under the conditions of an acceleration voltage of 15 kV and a magnification of 3,000 times. Is image-processed, and the surface occupation area ratio of the droplet (a granular material having high luminance on the SEM photograph) is obtained and averaged.

(D) Analysis of epitaxial growth at the interface between the lower layer and the upper layer An area including the interface between the lower layer and the upper layer is arbitrarily measured in a size of 100 nm × 100 nm at a magnification of 2 million times or 4 million times with a transmission electron microscope (TEM). FIG. 5 shows a schematic diagram of a typical interface obtained by observing 10 fields of view. As is apparent from FIG. 5, the lower layer crystal lattice stripe and the upper layer crystal lattice stripe are continuous in at least a part of the interface region between the lower layer and the upper layer in the mold of the present invention, and epitaxial growth was observed.
According to the study by the present inventors, the advantageous effects of the present invention are exhibited when 10% or more, preferably 30% or more, particularly preferably 50% or more of the interface shown in FIG. I found out.

[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, or the like is suitable. FIG. 1 shows an example of an AIP apparatus 1 that can be used in the present invention. The AIP apparatus 1 includes a rotatable base holder 11, lower layer forming sources (targets) 12 and 13 and shutters 22 and 23 thereof, and an upper layer forming unit in a decompression vessel 30 having a reaction gas supply pipe 16. Source (targets) 14 and 15 and shutters 24 and 25 thereof, and a bias power source 17 for applying a bias voltage to the substrate outside the decompression vessel 30. If the upper metal component is the same as the lower layer, the sources 14 and 15 and their shutters 24 and 25 may be omitted.

[3] Manufacturing Method (A) Formation of Lower Layer After the substrate is cleaned, the shutters 22 and 23 of the sources 12 and 13 are opened. The film forming temperature of the lower layer is preferably 550 to 700 ° C, more preferably 570 to 680 ° C, and most preferably 585 to 650 ° C. If the film forming temperature is less than 550 ° C., the residual stress of the lower layer is increased and the adhesion is lowered. On the other hand, if the film forming temperature exceeds 700 ° C., the residual stress is greatly reduced, and the hardness and mechanical strength of the film are reduced. In particular, as shown in Example 1 described later, when the lower layer film formation temperature and the upper layer film formation temperature are the same, the film formation process from the lower layer film formation process to the upper layer can be performed continuously without requiring temperature adjustment. So it is practical.

(1) Film formation atmosphere A mixed gas (reaction gas) of nitrogen gas and oxygen gas is used for the film formation atmosphere of the lower layer. The mixed gas may contain Ar gas. In this case, the ratio of Ar gas is preferably 70% by volume or less of the mixed gas, and more preferably 50% by volume or less. The pressure of the film forming atmosphere is 0.3 to 7 Pa, preferably 0.3 to 4 Pa, more preferably 0.3 to 3 Pa, and most preferably 0.5 to 2 Pa. When the film forming atmosphere pressure is outside the above range, it is difficult to form a lower layer.

(2) Change in flow rate of reaction gas Oxygen gas supplied during film formation of the lower layer in order to give the lower 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 The flow rate of nitrogen gas is gradually increased and 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 lower layer deposition. Point T ₁ indicates the time when the lower layer is formed, and point T ₂ indicates the time when the lower layer is completed.

In FIG. 2, the flow rate change pattern of nitrogen gas is represented by points B, C, and D, and the flow rate change pattern of oxygen gas is represented by points E, F, G, and H. In order to suppress oxidation in the first half of the lower layer deposition step, the oxygen gas flow rate at the start of deposition E is preferably 100 sccm or less, more preferably 50 sccm or less, and most preferably 10 sccm or less. It has been found that in order to obtain epitaxial growth from the lower layer to the upper layer, the oxygen gas flow rate at the film formation end point F needs to be 600 sccm or less. When the oxygen gas flow rate is over 600 sccm, a lot of droplets are generated, and a hard film excellent in adhesion and smoothness cannot be obtained. Further, the upper layer is formed too early, and epitaxial growth from the lower layer to the upper layer cannot be obtained. The oxygen gas flow rate at the film formation end point F is preferably 600 sccm or less, and more preferably 200 to 500 sccm. The upper layer may be formed after the lower layer is formed, but it is preferable to start the upper layer simultaneously with the practical upper and lower layers. Flow rate of the oxygen gas lower deposition end point is preferably reaches the flow rate of the oxygen gas in the upper layer of the film formation, both may not completely match. And the flow rate of the oxygen gas in the lower layer of the film-forming end point, the difference is preferably within 300sccm with the flow rate of the oxygen gas in the upper layer of the film formation, more preferably within 50 sccm, within most preferably 10 sccm.

In order to facilitate (a) nitride, while the nitrogen gas flow rate in the lower layer film formation start time T ₁ than 400 sccm, the flow rate of nitrogen gas in the film forming step the first half of 50sccm over more time than the oxygen gas flow rate 1 It has been found that it is necessary to increase the flow rate of oxygen gas to 600 sccm or less and decrease the flow rate of nitrogen gas during the period from the start to the end of (b) lower layer deposition. Nitrogen gas flow rate in the deposition starting point T ₁ of the lower layer is less than 400 sccm, the nitrogen gas flow rate in the first half of the film-forming step is not more than 50sccm than the oxygen gas flow rate, it becomes insufficient nitride, a desired lower layer obtained I can't. In addition, when the flow rate of oxygen gas supplied from the start to the end of the lower layer deposition exceeds 600 sccm, the generation of droplets becomes significant. Further, nitriding becomes insufficient when the nitrogen gas flow rate in the first half of the film forming process is 50 sccm or more higher than the oxygen gas flow rate for less than 1 minute. This time is preferably 2 to 120 minutes, more preferably 5 to 100 minutes. If it exceeds 120 minutes, the industrial productivity is greatly reduced. Further, unless the flow rate of nitrogen gas supplied from the start to the end of the lower layer film formation is decreased, a gradient of the nitrogen concentration cannot be imparted to the lower layer.

Since the oxygen concentration distribution in the lower layer has a positive gradient (increases from the lower layer side to the upper layer side), the oxygen gas flow rate change between the points E and 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 1 to 200 sccm / min, more preferably 3 to 100 sccm / min, further preferably 4 to 50 sccm / min. -40 sccm / min is most preferable, and 4-30 sccm / min is particularly preferable. The oxygen gas flow rate is ideally increased linearly, but may be increased stepwise. When the average gradient of the oxygen gas flow rate is less than 1 sccm / min, oxidation is insufficient, and when it exceeds 200 sccm / min, epitaxial growth cannot be obtained.

The nitrogen gas flow rate at the lower layer deposition start point B is 400 sccm or more, preferably 500 to 1500 sccm, and more preferably 600 to 1200 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 lower layer deposition end point C need not be completely 0 sccm, preferably 400 sccm or less, more preferably 100 sccm or less, Most preferred is 50 sccm or less. Since the nitrogen concentration distribution in the lower layer has a negative gradient (decreases from the lower layer side to the upper layer side), the change in the flow rate of nitrogen gas has a negative gradient in the period from point B to point C (T _{1 to} T ₂ ). . The average gradient of the nitrogen gas flow rate during the period (T _{1 to} T ₂ ) is preferably −200 sccm / min to −1 sccm / min, more preferably −100 sccm / min to −3 sccm / min, and −50 sccm / min to −5 sccm / min. Min is more preferred, -40 sccm / min to -5 sccm / min is most preferred, and -30 sccm / min to -5 sccm / min is particularly preferred. Ideally, the nitrogen gas flow rate decreases linearly, but it may decrease stepwise. If the average gradient of the nitrogen gas flow rate is less than -200 sccm / min, the nitrogen concentration gradient in the lower layer is too steep, and if it exceeds -1 sccm / min, a sufficient gradient composition cannot be obtained.

In FIG. 2, the lower layer deposition time (T _{1 to} T ₂ ) is 30 minutes, but is not limited. In order to sufficiently form the AlCr oxynitride lower layer, and from the viewpoint of industrial productivity, the film formation time (T _{1 to} T ₂ ) is preferably 5 to 180 minutes, and more preferably 10 to 60 minutes.

(3) Bias voltage The bias voltage applied to the substrate during film formation of the lower layer is preferably -150V to -10V. If it is less than −150 V, the residual stress is too large, and if it exceeds −10 V, the lower layer is not attached to the lower layer. When the energy of ions incident on the substrate is, for example, −50 V to −20 V and the ion energy incident on the substrate is lowered, a smooth lower layer is obtained. When the pulse bias voltage is used, the frequency is preferably 10 to 80 kHz in order to increase the adhesion of the lower 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 10V is sufficient.

(4) Arc current Since the lower layer contains low melting point Al, droplets are likely to be generated by rapid evaporation or abnormal ionization. In order to suppress this, it is preferable to keep the film-forming arc current (current applied to the arc evaporation source), which is a discharge current, in a low range of 100 to 150 A, and more preferably 100 to 140 A. If the arc current is less than 100 A, stable discharge is not maintained, and if it exceeds 150 A, a smooth lower layer cannot be obtained due to rapid evaporation of Al.

(B) Formation of upper layer After forming the lower layer, the shutters 25 and 26 of the upper layer forming sources 15 and 16 are opened to form the upper layer. When the upper layer metal component is the same as that of the lower layer, the lower layer source 14 may be used as it is .

(1) Film formation temperature The upper layer film formation temperature is preferably 590 to 700 ° C, more preferably 590 to 680 ° C, and still more preferably 595 to 650 ° C. If the film forming temperature is less than 590 ° C or more than 700 ° C, it is difficult to make TC (110) 1.3 or more .

(2) Film formation atmosphere Oxygen gas is used as a reaction gas for upper layer film formation. In order to prevent the droplets from reaching the substrate, the oxygen partial pressure in the film formation atmosphere needs to be 0.5 to 5 Pa, preferably 1 to 3 Pa. When the oxygen partial pressure is less than 0.5 Pa or more than 5 Pa, a TC (110) 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 of the film formation atmosphere, and more preferably 30% by volume or less. As shown in Table 18 described later, when 10 to 40% by volume of the film formation atmosphere is replaced with Ar gas, the effect of suppressing droplets can be sufficiently obtained.

(3) Oxygen gas flow rate The oxygen gas flow rate during upper layer deposition generally needs to be 100 to 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 lower layer cannot be obtained. The oxygen gas flow rate during upper layer deposition is preferably 200 to 500 sccm, more preferably 150 to 450 sccm, and most preferably 200 to 400 sccm. In FIG. 2, the time between the upper layer deposition start point G and the upper layer deposition end point H is 80 minutes, but is not limited. In order to sufficiently oxidize and from the viewpoint of industrial productivity, the film formation time of the upper layer is preferably 20 to 150 minutes, more preferably 40 to 100 minutes.

(4) Bias voltage The bias voltage applied to the substrate at the time of forming the upper layer is preferably −35V to −10V, more preferably −30V to −10V. 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 (110) dominant, and TC (110) 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 Al having a low melting point, droplets are likely to be generated due to rapid evaporation or abnormal ionization of Al. In order to suppress this, it is preferable to keep the film-forming arc current (current applied to the arc evaporation source), which is a discharge current, in a low range of 100 to 150 A, and more preferably 100 to 140 A. If the arc current is less than 100 A, film formation is impossible. Further, if it exceeds 150 A, rapid evaporation of Al is promoted, so that a smooth upper layer cannot be formed. By setting the arc current value within the specific range, welding resistance is ensured by AlCr oxide grains that are smooth, have few droplets, and are preferentially oriented in the (110) plane [TC (110) is 1.3 or more]. An upper layer having excellent properties and fracture resistance can be obtained.

  The above film forming conditions promote the generation of α-type Al oxide rather than the formation of α-type Cr oxide. It is a melted solid solution. The AlCr oxide crystal grains having the α-type crystal structure are preferentially oriented in the (110) plane, and the equivalent X-ray diffraction intensity ratio TC (110) is significantly increased.

Reducing the falling grains of the upper layer, in order to further improve adhesion, an upper brush may be smoothed by buffing or blasting. 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 non-metal element selected from C, N, B and O A hard protective film that requires the above may be formed.

  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 of the examples and comparative examples, the thickness of each layer was determined by measuring and averaging the 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 lower layer in the film thickness direction was defined as the average composition of the lower layer.

Example 1
(1) Formation of lower layer Cemented carbide substrate for cutting mold (CNMG120408) and cemented carbide substrate for measurement of physical properties (SNGA120408 and SNMN120408) comprising 6% by mass of Co, 94% by mass of WC and inevitable impurities Was set in a holder 12 in a large AIP apparatus 1 having the basic structure shown in FIG. The substrate is heated with a heater at the same time as evacuation, using an AlCr target (Al: 50 atomic%, Cr: 50 atomic%), film forming temperature: 600 ° C., bias voltage: −20 V, pulse bias frequency: 20 kHz, and AlCr As shown in FIG. 2, the current applied to the target is 120 A. As shown in FIG. 2, the flow rate of nitrogen gas is gradually decreased from 700 sccm to 200 sccm in 30 minutes (substantially linearly), and the flow rate of oxygen gas is increased in 30 minutes Gradually (substantially linearly) from 0 sccm to 500 sccm, the average composition of (Al _0.48 Cr _0.52 ) _0.45 (N _0.44 O _0.56 ) _0.55 (atomic ratio) A hard oxynitride lower layer having a thickness of 0.5 μm was formed. Atmospheric pressure from the start of film formation time T ₁ of the lower layer to the deposition end point T ₂ are controlled to 3 Pa.

(2) Formation of upper layer Using an upper layer AlCr target (Al: 25 atomic%, Cr: 75 atomic%) continuously from the formation of the lower layer, film forming temperature: 600 ° C., bias voltage: −20 V, pulse frequency : 20 kHz and the current applied to the AlCr target: 120 A, the flow rate of oxygen gas: 300 sccm, the flow rate of Ar gas: 100 sccm for 80 minutes, thereby maintaining (Al _0.26 Cr _0.74 ) ₂ O ₃ ( A hard oxide upper layer having a basic composition (atomic ratio) and having a thickness of 1.5 μm was formed. The partial pressure of oxygen gas at the time of forming the upper layer was 2.0 Pa.

(3) Analysis of the crystal structure of the upper layer To identify the crystal structure of the upper layer of the hard coating coated mold obtained, an X-ray diffractometer (RU-200BH) manufactured by Rigaku Corporation was used under the following conditions. X-ray diffraction measurement was performed.
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: 20-60 °

FIG. 3 shows the X-ray diffraction pattern of the upper layer surface. From FIG. 3, an α-type diffraction peak was observed. In the X-ray diffraction pattern of the upper layer shown in FIG. 3, α-type (012), (104), (110), (113), (024) and (116) peaks are observed. However, (202) face did not appear. In addition, α-type aluminum oxide and α-type chromium oxide have large standard X-ray diffraction intensity Io of (124) plane and (030) plane, but (110) plane and (002) plane of WC in a cemented carbide substrate. The distance between the surfaces is close and overlaps with the peaks of the (124) plane and (030) plane of α-type aluminum chrome oxide (AlCr) ₂ O ₃ , so the orientation is quantitatively determined using the (116) plane. evaluated.

  The inter-surface distance d, standard X-ray diffraction intensity Io, and 2θ described in ASTM file number 100173 of α-type aluminum oxide are shown in Table 1, and the inter-surface distance described in ASTM file number 381479 of α-type chromium oxide Table 2 shows the distance d, the standard X-ray diffraction intensity Io, and 2θ. Table 3 shows the inter-plane distance d, the X-ray diffraction intensities 1 and 2θ obtained from the X-ray diffraction pattern of Example 1. It can be seen that the inter-plane distance d obtained from the X-ray diffraction pattern of Example 1 (FIG. 3) is closer to α-type chromium oxide than to α-type aluminum oxide. Therefore, the standard X-ray diffraction intensity Io of α-type chromium oxide was used to determine the equivalent X-ray diffraction intensity ratio.

Using the following equivalent X-ray diffraction intensity ratios TC (110) and TC (104), the degree of orientation of the upper (110) plane and (104) plane was quantified .
T C (110) = [I (110) / I ₀ (110) / Σ [I (hkl) / 8I ₀ (hkl)]
TC (104) = [I (104) / I ₀ (104)] / Σ [I (hkl) / 8I ₀ (hkl) ]
( However, (hkl) is (012), (104), (110) , ( 113), (202), (024) and (116), and I ₀ (hkl) is the standard X of α-type chromium oxide) (Line diffraction intensity.)

(4) Composition analysis Using an electron probe microanalyzer (EPMA, JXA-8500F manufactured by JEOL Ltd.), under the conditions of an acceleration voltage of 10 kV, an irradiation current of 1.0 uA, and a probe diameter of 0.01 μm, the thickness direction of the lower layer The composition at the center was measured and taken as the average composition. When the thickness of the lower layer was 1 μm or more, the probe diameter was set to 0.5 × 2 μm. The average composition of the lower layer was 21.9 atomic% Al, 23.4 atomic% Cr, 23.8 atomic% N, and 30.9 atomic% O. The composition of the upper layer was 10.2 atomic% Al, 29.6 atomic% Cr and 60.2 atomic% O. As a result of X-ray diffraction, it was found that the upper layer had an α-type crystal structure.

(5) Measurement of oxygen concentration gradient and nitrogen concentration gradient in the lower 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 lower layer and the lower layer, and the lower layer The concentration distribution of oxygen and nitrogen in the thickness direction region including the interface with the upper layer was measured. The measurement results are shown in FIG. In FIG. 4, the scale on the vertical axis represents the total of the oxygen concentration and the nitrogen concentration as 100 atomic%. The horizontal axis represents the thickness from the interface between the substrate and the lower layer (0 μm). In the figure, ▲ indicates the nitrogen concentration, and ◯ indicates the oxygen concentration. 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 concentration of oxygen concentration and nitrogen concentration is expressed by rounding off the average gradient obtained from the measured value plot by the least square method.

(6) Analysis of epitaxial growth As a result of observing a region including the interface between the lower layer and the upper layer with a transmission electron microscope (TEM) at a magnification of 4 million times, at least a part of the interface region between the lower layer and the upper layer (100 nm × 100 nm in size) The lower layer crystal lattice fringe and the upper layer crystal lattice fringe were continuous for 30% of the interface region in any 10 fields of view, and epitaxial growth was observed.

(7) Measurement of surface roughness Ra Using a diamond stylus with a radius of curvature of 5 μm, a surface roughness measuring instrument (trade name: Surfcorder SE-30D, manufactured by Kosaka Laboratory Co., Ltd.) can be The surface roughness (Ra) was measured along five line segments (5 mm in length) and averaged.

(8) Measurement of surface area ratio (%) of droplet FIG. 6 is a scanning electron microscope (SEM) photograph of the upper surface taken at an acceleration voltage of 15 kV. An arbitrary area of 50 μm × 50 μm of this SEM photograph was subjected to image processing, and the surface occupation area ratio of the droplet (a granular material having high brightness on the SEM photograph) was determined. This calculation was performed on five SEM photographs (field of view), and the obtained surface occupation area ratio was averaged to obtain the surface occupation area ratio (%) of the droplet in the upper layer of the hard film-coated mold of Example 1. .
FIG. 7 is an SEM photograph of Comparative Example 6 to be described later, taken in the same manner as FIG.

(9) Measurement of mold life FIG. 15 shows a schematic diagram of the hard coating coated mold of the present invention used for measurement of the mold life. In FIG. 15, a punching punch 8 is obtained by coating a base made of the above-mentioned cemented carbide with the film of Example 1 or the like. Reference numeral 2 denotes a punching member on which the punch 8 is mounted. Reference numeral 3 denotes a pair of guides 3 and 3 provided to enable the punching member 2 to be moved with high accuracy at a predetermined speed in the vertical V direction. Reference numeral 5 denotes an upper mold, which has a hollow portion 5a (hole diameter: 0.15 mm) in the center, and is configured such that the tip portion 8a of the punch 8 can be inserted through the hollow portion 5a. Reference numeral 6 denotes a lower mold, which has a hollow portion 6a (hole diameter: 0.15 mm) in the center, and is configured such that the tip portion 8a of the punch 8 can be inserted through the hollow portion 6a. A punching process is performed with a punch 8 in a state in which a stainless steel thin plate 2 (made of SUS304, thickness 0.2 mm) to be used for the punching process is sandwiched between the upper mold 5 and the lower mold 6. The thin plate 2 is moved by a predetermined length in the direction perpendicular to the paper surface of FIG. 15 for each shot of punching, and punching is performed in a fixed state. In this way, the punching process was continuously performed, and the number of shots in which the punch 8 was broken or deformed and could not be punched was counted to obtain a “punch punch life”. The punching position of the thin plate 2 is selected so that the processing distortion of the punched portion does not affect the next punching portion, so that the thin plate 2 is continuously continuous in the direction perpendicular to the paper surface of FIG. The formed one was used.

Example 2
In order to investigate the influence of the content of Al and Cr in the upper layer, a hard coating was applied in the same manner as in Example 1 except that an AlCr target (Al: 40 atomic%, Cr: 60 atomic%) was used for the upper film formation. A mold was produced.

Example 3
In order to investigate the influence of the Al and Cr contents in the upper layer, a hard coating was applied in the same manner as in Example 1 except that an AlCr target (Al: 60 atomic%, Cr: 40 atomic%) was used for the upper film formation. A mold was produced.

Example 4
After forming the lower layer in the same manner as in Example 1, the same AlCr target as in Example 1 was used, and the film formation temperature: 600 ° C., bias voltage: −20 V, pulse bias frequency: 20 kHz, and AlCr target Applied current: 120 A, oxygen gas 225 sccm and Ar gas 75 sccm, oxygen gas partial pressure 1.5 Pa, (Al _0.25 Cr _0.75 ) ₂ O ₃ (atomic ratio) basic composition The upper layer was formed to a thickness of 1.5 μm .

Example 5
After forming the lower layer in the same manner as in Example 1, the same AlCr target as in Example 1 is used, and the film forming temperature is 600 ° C., the bias voltage is −20 V, the pulse bias frequency is 20 kHz, and the AlCr target is applied. Current: 120 sccm of oxygen gas and 40 sccm of Ar gas under the condition of 120 A, and a basic composition of (Al _0.24 C _0.76 ) ₂ O ₃ (atomic ratio) with an oxygen gas partial pressure of 1.0 Pa. The upper layer was formed to a thickness of 15 μm.

Example 6
In order to investigate the influence of the contents of N and O in the lower layer, a hard film-coated mold was produced in the same manner as in Example 1 except that the flow rates of nitrogen gas and oxygen gas were changed as shown in FIG. As is apparent from FIG. 8, in order to obtain an oxygen gas flow rate gradient of 6.7 sccm / min, the oxygen gas flow rate is set to 0 sccm at the lower layer deposition start time E, 200 sccm at the lower layer deposition end time F, and −6 In order to obtain a nitrogen gas flow rate gradient of 0.7 sccm / min, the nitrogen gas flow rate was set to 700 sccm at the lower layer deposition start point B and 500 sccm at the lower layer deposition end point C. The atmospheric pressure for forming the lower layer was 3 Pa.

Example 7
In order to investigate the influence of the N and O contents in the lower layer, the oxygen gas flow rate is set to 0 sccm at the lower layer deposition start time E, 650 sccm at the lower layer deposition end time F, and the nitrogen gas flow rate is set to the lower layer deposition start time B. A hard film-coated mold was prepared in the same manner as in Example 6 except that 700 sccm was used and that 10 sccm was set at the end C of the lower layer formation. The atmospheric pressure for forming the lower layer was 3 Pa.

  Table 4 shows the gas flow rate during lower layer deposition in Examples 6 and 7.

Examples 8 and 9
In order to investigate the influence of the content of Al and Cr in the lower layer, the composition of the AlCr target used for the lower layer film formation was Al ₁₀ Cr ₉₀ (atomic ratio) in Example 8, and Al ₆₀ Cr ₄₀ (atomic in Example 9). A hard film-coated mold was prepared in the same manner as in Example 1 except that the ratio was changed, and the same measurement as in Example 1 was performed.

Example 10
The same AlCr target as in Example 1 was used for the lower layer formed on the substrate in the same manner as in Example 1, film forming temperature: 600 ° C., bias voltage: −20 V, pulse bias frequency: 20 kHz, and AlCr target. Applied current: Ar flow of Ar gas at a constant amount (800 sccm) for 30 minutes under the condition of 120 A, and the nitrogen gas flow rate is gradually decreased from 700 sccm at the start of lower layer deposition to 200 sccm in 30 minutes, and the oxygen gas flow rate is lowered to the lower layer. Gradually increase from 0 sccm at the start of film formation to 500 sccm in 30 minutes, and (Al _0.53 Cr _0.47 ) _0.35 (N _0.43 O _0.57 ) _0.65 (atomic ratio) at an atmospheric pressure of 7 Pa The lower layer which has a composition represented by this was formed in the thickness of 0.5 micrometer. Thereafter, an upper layer having a basic composition of (Al _0.25 Cr _0.75 ) ₂ O ₃ (atomic ratio) was formed to a thickness of 1.5 μm in the same manner as in Example 1.

Example 11
The same AlCr target as in Example 1 was used for the lower layer formed on the substrate in the same manner as in Example 1, film forming temperature: 600 ° C., bias voltage: −20 V, pulse bias frequency: 20 kHz, and AlCr target. Applied current: 120 A, the flow rate of nitrogen gas is gradually decreased from 400 sccm at the start of lower layer deposition to 100 sccm in 30 minutes, and the flow rate of oxygen gas is gradually increased from 0 sccm at the start of lower layer deposition to 200 sccm in 30 minutes. The lower layer having a composition represented by (Al _0.50 Cr _0.50 ) _0.60 (N _0.47 O _0.53 ) _0.40 (atomic ratio) at an atmospheric pressure of 2.0 Pa is reduced to 0. A thickness of 5 μm was formed. Thereafter, an upper layer having a basic composition of (Al _0.25 Cr _0.75 ) ₂ O ₃ (atomic ratio) was formed to a thickness of 1.5 μm in the same manner as in Example 1.

Example 12
A lower layer was formed in the same manner as in Example 1 except that the supply pattern of the oxygen gas flow rate and the nitrogen gas flow rate was changed as shown in FIG. The nitrogen gas flow rate was 1000 sccm at the film formation start time B ₂ and 500 sccm at the point C ₁ , and the average gradient of the nitrogen gas flow rate between the points B ₂ and C ₁ was −8.3 sccm / min. Between the point _{C 1} of the point _{C 2} to nitrogen gas flow rate constant (500 sccm). The oxygen gas flow rate was 0 sccm at the film formation start time E, 500 sccm at the film formation end time F, and the average gradient was 4.2 sccm / min. Further, at point F, the oxygen gas flow rate was reduced from 500 sccm to 300 sccm. The atmospheric pressure for forming the lower layer was 4 Pa. FIG. 10 shows oxygen and nitrogen concentration distributions measured by EELS in the same manner as in Example 1. Before the time point T ₂ (corresponding to the points C ₂ and F) in FIG. 9, the oxygen concentration is in a region substantially above the middle of the lower layer as shown in FIG. 10 even though the oxygen gas flow rate is lower than the nitrogen gas flow rate. Is higher than the nitrogen concentration. On the obtained lower layer, an upper layer having a basic composition of (Al _0.25 Cr _0.75 ) ₂ O ₃ (atomic ratio) was formed to a thickness of 1.8 μm in the same manner as in Example 1.

Comparative Example 1
Using an AlCr target (Al: 4 atomic%, Cr: 96 atomic%), s = 0.04 and t = 0.96 in the general formula: (Al _s Cr _t ) _a (N _v O _w ) _b A hard film coated mold was produced in the same manner as in Example 1 except that a certain lower layer was formed.

Comparative Example 2
Using an AlCr target (Al: 70 atomic%, Cr: 30 atomic%), s = 0.70 and t = 0.30 in the general formula: (Al _s Cr _t ) _a (N _v O _w ) _b A hard film coated mold was produced in the same manner as in Example 1 except that a certain lower layer was formed.

Comparative Example 3
A hard film-coated mold was prepared in the same manner as in Example 10 except that the Ar gas flow rate was kept constant (1000 sccm) and the atmospheric pressure was set to 8 Pa in the lower layer deposition step.

Comparative Example 4
The nitrogen gas flow rate is gradually decreased from 200 sccm at the start of lower layer deposition to 50 sccm in 30 minutes, and the oxygen gas flow rate is gradually increased from 0 sccm at the start of lower layer deposition to 100 sccm in 30 minutes to lower the atmospheric pressure of the lower layer deposition. A hard coating mold was produced in the same manner as in Example 11 except that the pressure was changed to 1.0 Pa.

Comparative Example 5
Implemented except that the flow rate of nitrogen gas is constant (0 sccm) and the oxygen gas flow rate is gradually increased from 0 sccm at the start of film formation to 700 sccm in 30 minutes in the lower layer deposition process. In the same manner as in Example 1, a hard film-coated mold was produced.

Comparative Example 6
Implemented except that the flow rate of oxygen gas was kept constant (0 sccm) in the lower layer deposition process, and the nitrogen gas flow rate was gradually decreased from 900 sccm at the start of deposition to 700 sccm over 30 minutes (substantially linearly). In the same manner as in Example 1, a hard film-coated mold was produced.

Comparative Example 7
A small AIP apparatus 1 having the basic structure shown in FIG. 1 is used except that the flow rates of oxygen gas and nitrogen gas are constant (500 sccm) and the pressure is 4 Pa in the lower layer film forming step as shown in FIG. In the same manner as in Example 1, a hard film-coated mold was produced, and the same measurement as in Example 1 was performed. The concentration distribution of oxygen and nitrogen in the thickness direction of the region including the interface between the lower layer and the lower layer and the interface between the lower layer and the upper layer was measured by the EELS method. The results are shown in FIG. As is clear from FIG. 12, the oxygen concentration in the lower layer was substantially the same from the lower layer side to the upper layer side. From this, it can be seen that under the lower layer deposition conditions of Comparative Example 7, the gradients of oxygen concentration and nitrogen concentration are not formed.

Comparative Example 8
As a trace experiment of JP 2010-506049, a hard coating was applied in the same manner as in Comparative Example 7 except that the flow rates of oxygen gas and nitrogen gas were respectively constant (1000 sccm) and the pressure was 8 Pa in the lower layer film forming step. A mold was produced. As a result of performing the same measurement as in Example 1 on this mold, no gradient of oxygen concentration and nitrogen concentration in the lower layer was observed.

Comparative Example 9
Using the small AIP apparatus 1 having the basic structure shown in FIG. 1, as a trace experiment of the lower layer film forming conditions (nitrogen gas and oxygen gas supply pattern) described in paragraph 61 of JP-T-2010-506049, FIG. As shown in FIG. 4, the nitrogen gas flow rate was kept constant (100 sccm), the oxygen gas flow rate was increased almost linearly from 50 sccm at the start of film formation to 1000 sccm, and the film formation atmosphere pressure was increased to 4 Pa in 10 minutes. In the same manner as in Example 1, a hard film-coated mold was produced. As a result of performing the same measurement as that of Example 1 on this mold, almost no nitriding occurred because the nitrogen gas flow rate was too low, and no gradient of oxygen concentration and nitrogen concentration in the lower layer was observed.

Comparative Example 10
By forming a Ti (CN) lower layer, a Ti (NO) lower layer and an α-type Al ₂ O ₃ layer on the same substrate as in Example 1 by chemical vapor deposition, a hard film-coated mold was prepared. The same measurement was performed.
The schematic view of FIG. 5 shows the result of observing the region including the interface between the lower layer and the upper layer with a transmission electron microscope (TEM) at a magnification of 2 million times or 4 million times. As is clear from FIG. 5, at least part of the interface region between the lower layer and the upper layer, the lower layer crystal lattice fringe and the upper layer crystal lattice fringe were continuous, and epitaxial growth was observed. It was observed that the lower layer crystal lattice fringe and the upper layer crystal lattice fringe were continuous in a region corresponding to at least 20% of the predetermined length along the interface in five typical visual fields of this TEM observation.
Lower and upper film formation method of each of Examples and Comparative Examples, the type and thickness, as well as continuous variation of O and N of the presence or absence of (continuous increase and continuous decrease of N O) are shown in Table 5 . It shows the underlying composition in Table 6. It shows the film formation conditions and the graded composition of the lower layer in Table 7. It shows the deposition conditions and composition of the upper layer shown in Table 8. Of the upper layer thickness shows the crystal structure, the equivalent X-ray diffraction intensity ratio TC (110), TC (104 ), Table roughness Ra and the droplet surface area share ratio, as well as the mold life in Table 9.

Examples 13-16, Comparative Example 11
A hard film-coated mold was prepared 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 (110), and mold life were measured. The measurement results are shown in Table 10 together with the film formation temperature .

Examples 17-19, Comparative Examples 12 and 13
Except for changing the bias voltage at the time of forming the upper layer as shown in Table 11, a hard coating coated mold was prepared in the same manner as in Example 1, and the upper layer crystal structure, TC (110), and mold life were increased. It was measured. The measurement results are shown in Table 11 together with the bias voltage.

Examples 20 and 21, Comparative Examples 14 and 15
A hard coating coated mold was prepared in the same manner as in Example 1 except that the 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, TC (110), and mold Lifespan was measured. The measurement results are shown in Table 12 together with the atmospheric pressure.

Examples 22-23
A hard coating coated mold 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, TC (110), and mold life were obtained. Was measured. The measurement results are shown in Table 13 together with the flow rate of oxygen gas. As apparent from Table 13, a TC (110) of 1.3 or more and a long mold life were obtained when the flow rate of oxygen gas was in the range of 100 to 500 sccm. In particular, since the mold life was long when the flow rate of oxygen gas was in the range of 200 to 400 sccm, the surface roughness of the upper layer was measured in the same manner as in Example 1 in order to investigate the cause. As a result, in Examples 1, 23, and 24 where the flow rate of oxygen gas is 200 sccm, 300 sccm, and 400 sccm, the average surface roughness Ra of the upper layer is 0.079 μm and 0.082 μm, and the flow rate of oxygen gas is 500 sccm. 25, the average surface roughness Ra of the upper layer was 0.145 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 150 to 450 sccm, particularly in the range of 200 to 400 sccm.

Examples 26-29
A hard film-coated mold was prepared in the same manner as in Example 1 except that the lower layer thickness and the upper layer thickness were changed by changing the lower layer or upper layer deposition time, and the upper layer crystal structure and TC (110 ) As well as the mold life. The results are shown in Table 14.

  Each of the hard coating coated molds of Examples 26 to 29 having a lower layer thickness (Tl) of 0.2 to 3.0 μm and an upper layer thickness (Tu) of 0.3 to 6 μm had a long life. From this, it can be seen that Tl is preferably 0.1 to 4 μm, and Tu is preferably 0.2 to 8 μm. In addition, TC (110) of Examples 28 and 29 are 2.55 and 3.58, which are remarkably high. Although this mechanism is not necessarily clear, in the range of the upper layer thickness of 4 to 6 μm, TC (110) tended to increase significantly as the upper layer thickness increased.

Examples 30 and 31, Comparative Examples 16 and 17
Except for changing the arc current at the time of forming the upper layer as shown in Table 15, a hard coating coated mold was prepared in the same manner as in Example 1, and the crystal structure of the upper layer, TC (110), and mold life were increased. It was measured. The measurement results are shown in Table 15 together with the arc current. From Table 15, it can be seen that high performance is obtained when the arc current during film formation of the upper layer is 100 to 150A.

Examples 32-34
As shown in Table 16, when the upper layer deposition atmosphere is composed of oxygen gas and Ar gas (Examples 33 and 34), and when the upper layer deposition atmosphere is composed only of oxygen gas (Example 32). In the same manner as in Example 1 except for the substitution ratio of Ar gas to oxygen gas, a hard film-coated mold was prepared, and the upper layer crystal structure, TC (110), and mold life were measured. The measurement results are shown in Table 16 together with the Ar gas substitution ratio.
From Table 16, it can be seen that in Examples 33 and 34 in which 10 to 40% by volume of the oxygen gas in the upper layer film formation atmosphere is replaced with Ar gas, the generation of droplets is remarkably suppressed. In addition, it can be seen that the generation of droplets is less in the case of Example 32 where the upper layer film formation atmosphere is composed of only oxygen gas (however, inevitable impurities are allowed) as compared with the comparative example.

  FIG. 14 shows the relationship between the TC (110) of the hard film coated molds of Examples 1 to 34 and Comparative Examples 10, 12, 13, 15, and 17 and the lifetime. In FIG. 14, ● represents an example, and ▲ represents a comparative example. The lifetimes of the hard coating coated molds of Examples 1 to 34 are all over 5000 times, and in particular, Examples 1, 2, 6 to 9, 11, 14, 17, and TC (110) of 1.5 or more. 18, 20, 23, 24, 28, 29, 30, 33, 34 had a mold life of 18000 times or more. In Example 26, since the lower layer was as thin as 0.2 μm, the mold life was less than 17000 times even when TC (110) was 1.5 or more.

  In contrast, the mold life of the comparative example was short. The mold of the present invention has such a long life because the upper layer strongly oriented in the (110) plane is formed of fine AlCr oxide crystal grains, and the crystal grains are less dropped and have high adhesion. This is considered to be because of excellent chipping resistance. When TC (110) was 1.5 to 3.58, a very long mold life was obtained.

In the above embodiment, the case where the lower layer and the upper layer are coated directly on the substrate is described, but the present invention is not limited to this.
Although the practicality is considered to be slightly lower than in the above examples, it is also preferable to interpose another hard layer formed by physical vapor deposition between the substrate and the lower layer in the present invention. By interposing this another hard layer, the hard coating coated mold of the present invention can have a longer life. This other intervening layer was selected from the group consisting of 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 B, for example. It is a hard film composed of at least one nonmetallic element. As a nonmetallic element, it is preferable that N is essential. Specific examples of another hard layer formed by physical vapor deposition between the substrate and the lower layer include TiAlN, TiAlNbN, TiSiN, TiAlCrN, TiAlWN, AlCrSiN, CrSiBN, TiAlCN, TiSiCN, and AlCrSiCN. In order to improve the adhesion with the lower layer, it is preferable to contain Al or Cr. Between these substrates and the lower layer, another hard layer formed by physical vapor deposition has an fcc structure, preferably oriented in the (111) plane. The thickness of another hard layer formed by physical vapor deposition between the substrate and the lower layer is preferably 0.5 to 10 μm, more preferably 0.5 to 6 μm, and most preferably 1 to 5 μm.

  Although the case where the lower layer and the upper layer according to the present invention are coated only on the surface of the punch 1 is described in the hard coating coated mold 10 of the present invention in FIG. 15, it is not particularly limited. For example, the surface of the cavities 5a and 6a of the upper mold 5 and the lower mold 6 in FIG. 15 may be coated with the lower layer and the upper layer according to the present invention. Furthermore, the lower layer and the upper layer according to the present invention may be coated only on the surfaces of the cavities 5a and 6a of the upper mold 5 and the lower mold 6 in FIG.

Industrial application fields

  Examples of industrial fields to which the hard coating coated mold of the present invention can be applied include metal working molds represented by forging molds, powder metallurgy molding molds, casting molds, plastic molding molds, etc. And can be widely applied to broadly defined molds. The hard film coated mold of the present invention has a significantly improved mold life compared to the conventional one, and is extremely useful in industry.

8 Punch 2 Punching member 3 Guide pin 5 Upper mold 5a Upper mold hollow 6 Lower mold 6a Lower mold hollow 10 Mold

Claims (6)

A hard film coating mold in which a hard film is formed on a substrate by physical vapor deposition,
The hard coating has a lower layer and an upper layer formed on the lower layer,
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 are numbers representing the atomic ratio of AlCr and O) X = 0.1 to 0.6, x + y = 1, c = 1.86 to 2.14, and d = 2.79 to 3.21) and an α-type crystal structure, and an equivalent X-ray diffraction intensity ratio TC (110) is made of oxide with 1.3 or more,
The lower layer is made of an oxynitride essentially containing Al and Cr as metal elements, and 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. And the average composition is represented by the general formula: (Al _s Cr _t ) _a (N _v O _w ) _b (where s and t are numbers representing the atomic ratio of Al and Cr, and v and w are N and O A and b are numbers representing the atomic ratio of AlCr and NO, and the following conditions:
s = 0.1-0.6,
s + t = 1,
v = 0.1-0.8,
v + w = 1,
a = 0.35-0.6,
And a + b = 1. )
The hard film-coated mold, wherein the lower layer crystal lattice fringes and the upper layer crystal lattice fringes are at least partially continuous at the interface between them.   2. The hard film coated mold according to claim 1, wherein the upper layer has an equivalent X-ray diffraction intensity ratio TC (110) larger than an equivalent X-ray diffraction intensity ratio TC (104).   3. The hard film-coated mold according to claim 1, wherein the upper layer has a surface roughness Ra of 0.2 μm or less. In hard-coated mold according to claim 1, the thickness of the lower layer (Tl) is 0.1～4Myuemu, the thickness of the upper layer (Tu) is 0.2~8μm, Tl ≦ Hard film coated mold characterized by satisfying the relationship of Tu.   5. The hard coating mold according to claim 1, wherein an average gradient of oxygen concentration in the gradient composition of the lower layer from the lower layer side to the upper layer side is 10 to 600 atomic% / μm. Hard film coated mold characterized by   6. The hard film coated mold according to claim 1, wherein an average gradient of nitrogen concentration in the gradient composition of the lower layer from the lower layer side to the upper layer side is −650 to −10 atomic% / μm. A hard film-coated mold characterized by being.