JP4718382B2 - Hard coating - Google Patents

Description

  The present invention relates to a hard film formed on the surface of a base material of a jig used for forging, press molding, extrusion molding, or the like, or a jig for plastic working such as a punching punch.

  In forming using various jigs for plastic working as described above, forming is performed at higher speed and higher surface pressure to improve productivity, and less lubricant is required from the viewpoint of environmental problems. Tend to be processed using. Under such circumstances, the surface of the mold substrate (high-speed steel, cold, hot mold steel, etc.) alone will be seriously damaged, so surface hardening treatment such as nitriding or the like may be applied to the surface. It is common to enhance the surface characteristics by coating.

Among these, for example, Patent Document 1 discloses that a surface coating method is applied to improve wear resistance by forming a VC-based film on the surface of a mold base material. Applicability is also disclosed. On the other hand, in Patent Document 2, nitrides, carbonitrides and carbonates of (Al _1-x V _x ) (where x = 0.24 to 0.45) are useful as hard coatings for cutting tools. It is shown that there is.
JP 2002-371352 A JP-A-2005-271106

Since the VC-based film as described above has low oxidation resistance and starts oxidation at around 400 to 500 ° C., the film deteriorates significantly in severe environments due to heat generated by friction with the workpiece during plastic processing. There is a problem. In addition, the Cr-based film is low in hardness, poor in lubricity (friction resistance at the interface between the workpiece and the film), and has high corrosion resistance, so reprocessing by film removal is difficult. In particular, when the film has poor lubricity, when it is applied to various plastic working jigs as described above, the frictional resistance at the contact surface is increased, and seizure to the jigs may occur. . On the other hand, a hard film made of nitride, carbonitride and carbonate of (Al _1-x V _x ) (where x = 0.24 to 0.45) has good oxidation resistance at high temperatures. The lubricity is still insufficient.

  The present invention has been made paying attention to the above-mentioned circumstances, and its purpose is not only excellent in wear resistance but also oxidation even under circumstances where high temperature heat generation is likely to occur due to frictional heat generation. An object of the present invention is to provide a hard film having an appropriate lubricity without causing deterioration of characteristics due to the above.

The hard coating of the present invention that has solved the above problems is a hard coating formed on the surface of a substrate, and two or more different types of films are laminated in one layer or two or more layers, respectively, Has a gist in that it is a film represented by the following formula (1).
(Al _1-abc V _a Si _b B _c ) (C _1-x N _x ) (1)
However, 0.27 ≦ a ≦ 0.9, 0 ≦ b + c ≦ 0.2, 0.1 ≦ x ≦ 1.0
[Subscripts in the formula indicate atomic ratios independent of each other]

  In the hard film of the present invention, when laminating mutually different films, two or more kinds of films in which the values of x in the formula (1) are different from each other are each one layer or two or more layers. What was comprised by laminating | stacking is illustrated.

In the hard film of the present invention as described above, it is preferable that the film represented by the following formula (2) and having a film thickness of 5 μm or more is formed as an underlayer on the substrate surface. It is done. In the film used as the underlayer, it is preferable that the element M constituting the film contains at least Cr and the atomic ratio of Cr in the element M is 0.3 or more.
M (C _1-y N _y ) (2)
However, 0 ≦ y ≦ 1.0
[M represents at least one element selected from Group 4A elements, Group 5A elements, Group 6A elements, Al, Si and B in the periodic table; y represents an atomic ratio]

As the hard film (hard film formed on the substrate surface) of the present invention, a film represented by the following formula (3) and a film represented by the following formula (4) are each laminated in one layer or two or more layers. The above object can be achieved even with a hard film having such a structure.
(Al _1-abc V _a Si _b B _c ) (C _1-x N _x ) (3)
However, 0.27 ≦ a ≦ 0.9, 0 ≦ b + c ≦ 0.2, 0.1 ≦ x ≦ 1.0
[Subscripts in the formula indicate atomic ratios independent of each other]
M (C _1-y N _y ) (4)
However, 0 ≦ y ≦ 1.0
[M represents at least one element selected from Group 4A elements, Group 5A elements, Group 6A elements, Al, Si and B in the periodic table; y represents an atomic ratio]

  Further, even when such a hard film configuration is employed, it is preferable that the film shown in (4) and having a film thickness of 5 μm or more is formed on the substrate surface as an underlayer. In the film used as the underlayer, it is preferable that the element M constituting the film contains at least Cr, and the atomic ratio of Cr in the element M is 0.3 or more.

  The hard coating of the present invention has a structure in which an AlV-based film represented by a predetermined formula is laminated, so that it has not only excellent wear resistance but also high temperature heat generation due to frictional heat generation. It is possible to realize a hard film having moderate lubricity without causing deterioration of properties due to oxidation, and such a hard film can be used for metal working for forging, press molding, extrusion molding, and plastic processing such as punching punch. It is extremely useful as a tool formed on the surface of a base material for a tool.

The present inventors have studied from various angles in order to realize a hard film excellent in both high temperature resistance (oxidation resistance) and lubricity. As a result, if the film is represented by the following formula (1) and two or more kinds of films different from each other are laminated in one layer or two or more layers to form a laminated type film, the above object is achieved. The present invention was completed by finding out that it was accomplished brilliantly. “Two or more different films” means that the composition or film forming conditions are changed to change characteristics such as film hardness, film structure [crystal orientation and properties (columnar, microcrystal)], etc. Means different. The film formation conditions are, for example, a bias voltage applied to the substrate during film formation, temperature, gas pressure during film formation, or the like.
(Al _1-abc V _a Si _b B _c ) (C _1-x N _x ) (1)
However, 0.27 ≦ a ≦ 0.9, 0 ≦ b + c ≦ 0.2, 0.1 ≦ x ≦ 1.0
[Subscripts in the formula indicate atomic ratios independent of each other]

In the hard film of the present invention, each layer constituting the hard film has a composition represented by the above formula (1) (hereinafter, sometimes referred to as “AlV-based film”). The effect of V in such an AlV-based film is that a low-melting point oxide such as V ₂ O ₅ is formed in a high-temperature oxidation environment, and this low-melting point oxide is soft, so friction at the interface between the workpiece and the film The purpose is to increase the lubricity by reducing the resistance. However, V alone is very easy to oxidize and becomes insufficient in terms of oxidation resistance. Therefore, Al is added to obtain an AlV-based film as described above, and by adjusting the amount of Al added, The oxidation resistance can be controlled, and characteristics according to the processing conditions can be imparted.

  Therefore, the characteristics of the AlV-based film depend on the Al amount (or V amount), and if the Al amount increases, the oxidation resistance becomes higher and it can be used at a high temperature. Becomes lower. Therefore, the lower limit of the atomic ratio of V in the film needs to be 0.27 (that is, the subscript a is 0.27 or more). Further, when the Al amount is reduced, the oxidation resistance of the film is lowered, and the oxidative deterioration of the film becomes remarkable. Therefore, the upper limit of the atomic ratio of the V amount in the film is 0.9 (ie, a ≦ 0.9). There is a need to. A preferable range of the V amount is 0.4 to 0.7 (0.4 ≦ a ≦ 0.7) in terms of atomic ratio, and more preferably 0.5 to 0.6 (0.5 ≦ a ≦ 0. 6).

  C exhibits the effect of imparting lubricity to the film, but as the amount of C increases (that is, the value of the subscript x in the above formula (1) decreases), an unstable Al compound is formed. Therefore, it is a guideline that the C amount is approximately the same as the V addition amount, and the upper limit is set to 0.9 (that is, x ≧ 0.1). A preferable upper limit of the amount of C is 0.7 in terms of atomic ratio (that is, x ≧ 0.3), and more preferably 0.5 or less (that is, x ≧ 0.5). When C is not added (that is, when the value of x is 1 and the film is a nitride), the lubricity of the film is slightly lowered and the frictional resistance is increased, but it can be used without any problem depending on the application.

  The hard film of the present invention is a film of the above-described formula (1), which is a laminated film obtained by laminating two or more different films in one layer or two or more layers. By adopting, it is possible to exhibit more outstanding characteristics in each characteristic (wear resistance, oxidation resistance and lubricity) as compared with the case of a single layer. In other words, a film with low hardness exhibits excellent lubricity with a low friction coefficient, but a film with low wear resistance and a film with high hardness has excellent wear resistance but low lubricity. By laminating, it was possible to exhibit excellent wear resistance and lubricity.

  From this point of view, it is necessary to make at least two kinds of each film constituting the multi-layered hard film. However, the effect is saturated by forming too many kinds of films. It is good to use up to about 3 types. The thickness of each layer is preferably at least 2 nm or more, more preferably 5 nm or more because there is no difference in characteristics from a uniform film (single layer film) if it is less than 2 nm. However, if the thickness of each layer becomes too large, the effect of stacking becomes small, so the upper limit is preferably about 100 nm. Further, the total film thickness of such a laminated film needs to be at least about 3000 nm, more preferably 5000 nm, considering long-term durability due to wear. Moreover, since it will become easy to peel by residual stress etc. when the whole film thickness exceeds 10,000 nm (10 micrometers), it is preferable that it is below this.

  By the way, as described above, two or more kinds of films different from each other means that characteristics such as film hardness and film structure are different due to different compositions, but “compositions are different from each other”. In the above formula (1), the amount of V (ie, the value of a) is made different from each other, or the amount of C (ie, the value of x) is made different from each other to make the composition different. is there. Among these, increasing the amount of C improves lubricity, and decreasing the amount of C improves hardness and wear resistance. Therefore, the amount of C (that is, the value of x) is made different from each other. Therefore, it is preferable because both lubricity and wear resistance can be achieved. However, each layer constituting the hard coating is within the range of the composition represented by the above formula (1).

  In the hard coating of the present invention, it is also useful to add Si and / or B to the coating constituting each layer [that is, when b + c is not 0 in the above general formula (1)]. When Si or B is added, the crystal grains of the AlN-based film can be refined and the hardness is further improved. The details of the grain refinement effect due to the addition of Si and B are not clear, but the growth of crystal grains is suppressed by the formation of Si-N bonds and BN bonds at the grain boundaries. it is conceivable that. The addition amount of Si or B [(b + c) in the above formula (1)] is preferably 0.01 or more in terms of atomic ratio, and more preferably 0.05 or more. However, if the addition amount of Si or B is excessive, the crystal structure of the AlV-based film is transitioned from a high hardness cubic type to a hexagonal type and softened, so b + c is 0.2 or less. It is necessary to set it to 0.10 or less.

When the above hard coating (laminated hard coating) was formed on the surface of an iron-based substrate (cold tool steel, hot tool steel, high-speed tool steel, etc.), it was deposited on the surface of the substrate. Damage such as film peeling may occur under the influence of non-uniform mechanical properties existing on the substrate surface due to carbides and the like. From the viewpoint of avoiding such inconvenience, it is preferable to form a film represented by the following formula (2) as a base layer (that is, an intermediate layer between a hard film and a base material) on the substrate surface.
M (C _1-y N _y ) (2)
However, 0 ≦ y ≦ 1.0
[M represents at least one element selected from Group 4A elements, Group 5A elements, Group 6A elements, Al, Si and B in the periodic table; y represents an atomic ratio]

  In the above formula (2), M is a periodic table group 4A element, group 5A element, group 6A element (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, etc.), Al, Si and B At least one element selected from the group consisting of Ti (CN), TiAl (CN), TiCrAl (CN), and V (CN). TiSi (CN), AlCr (CN), and the like.

  The film used as the underlayer is effective in suppressing the influence of non-uniform mechanical properties existing on the substrate surface. Is preferably 5 μm or more, and more preferably 7 μm or more. The upper limit of the film thickness is not particularly limited, but if it exceeds 50 μm, the effect tends to be saturated.

  The film used as the underlayer includes at least Cr as the element M constituting the film of the film represented by the above formula (2), and the atomic ratio of Cr in the element M is 0.3 or more. Some are preferred (carbides, nitrides, carbonitrides). In particular, carbides, nitrides, and carbonitrides containing Cr in an atomic ratio of 0.3 or more have excellent adhesion to iron-based substrates. That is, in a film in which the atomic ratio of Cr is less than 0.3, the adhesion with the iron-based substrate is lowered, the film is too hard and the residual stress is increased, and the film thickness is 5 μm or more. Film formation becomes difficult.

  Of those having an atomic ratio of Cr of 0.3 or more in the element M, for example, CrN is a substance that is inherently excellent in corrosion resistance, so that it is difficult to remove the film by a wet method. When such a situation is expected, film removal can be easily performed by further adding an element such as Al or W to a film containing Cr in an atomic ratio of 0.3 or more. In order to exert such an effect, the amount of the element M (Al or W) added is preferably 0.05 or more, more preferably 0.1 or more in terms of atomic ratio.

  As the hard film of the present invention, a film represented by the formula (3) [substantially the same as the film represented by the formula (1)] and a film represented by the formula (4) [substantially the above It is also useful that the same as the film represented by the formula (2) is a structure in which one layer or two or more layers are laminated. Even with such a laminated hard film, lubricity or oxidation resistance can be selectively imparted according to the use conditions, and as a result, a longer life can be realized compared to a single-layer hard film. Become. In the laminated hard film having such a structure, the film represented by the formula (4) basically has a composition to be applied as an underlayer, but priority is given to heat resistance (oxidation resistance) at high temperatures. In the case of a target, a TiAl (CN) film or TiCr (CN) film containing 0.4 or more Al in atomic ratio to the element M, or TiAlSi containing 0.03 or more Si in atomic ratio to the element M A (CN) film or a TiSi (CN) film is preferred. In the case where priority is given to lubricity, carbides, nitrides, and carbonitrides containing one or more of V, W, and Mo in an atomic ratio with respect to the element M of 0.2 or more are preferable.

  Even in the case of forming a hard film having such a structure, the thickness of each layer is preferably 2 nm or more, more preferably 5 nm or more from the viewpoint of making a difference in characteristics from a uniform film (single layer film). It is good to do. Even in the case of constituting such a hard film, it is preferable that the film represented by the formula (4) is formed on the substrate surface as an underlayer (that is, an intermediate layer between the hard film and the base material). . The preferable range of the entire film thickness is the same as described above.

  The various hard coatings of the present invention can be produced by known methods such as physical vapor deposition (PVD method) and chemical vapor deposition (CVD). From the viewpoint of film adhesion, it is preferable to manufacture using the PVD method. Specific examples include sputtering, vacuum deposition, and ion plating. Preferably, a gas phase coating method [sputtering or ion plating (particularly, arc ion plating)] is employed. Is recommended.

  FIG. 1 is a schematic explanatory view showing a configuration example of an arc ion plating apparatus (AIP apparatus) for producing a hard coating of the present invention. In the apparatus shown in FIG. 1, a turntable 2 is disposed in a vacuum chamber 1, and four turntables 3 are attached to the turntable 2 symmetrically. An object (base material) 5 to be processed is attached to each turntable 3. Around the turntable 2, a plurality (four in FIG. 1) of arc evaporation sources 6a, 6b, 6c, 6d (cathode side) and heaters 7a, 7b, 7c, 7d are arranged. Further, arc power sources 8a, 8b, 8c, and 8d for evaporating each of the arc evaporation sources 6a, 6b, 6c, and 6d are disposed. The inside of the vacuum chamber 1 is configured to be evacuated by a vacuum pump P, and various film forming gases are introduced from the mass flow controllers 9a, 9b, 9c, and 9d.

  And each arc evaporation source 6a, 6b, 6c, 6d uses the target of various compositions, These are made into film-forming gas (N source containing gas, C source containing gas and N source containing gas, or these as inert gas) If the turntable 2 and the turntable 3 are rotated while evaporating in the liquid etc. diluted in the above, a hard film can be formed on the surface of the object 5 to be processed. In the figure, reference numeral 10 denotes a bias power source provided for applying a negative voltage (bias voltage) to the substrate 5.

  Moreover, in order to make a hard film into a laminated type, it can be realized by (1) using a plurality of different arc evaporation sources 6a, 6b, 6c, 6d, but (2) a negative voltage applied to the object 5 ( This can also be realized by periodically changing (bias voltage) or (3) changing the atmospheric gas. In particular, in order to stack two or more kinds of films having different values of x in the formula (1), the ratio of the C source-containing gas in the atmospheric gas is periodically changed.

  In order to control the period of the laminated hard coating (repetition period of lamination) and the thickness of each layer, in the above (1), the rotation speed of the rotary table and rotary table and the input power of each evaporation source (proportional to the evaporation amount) (2) can be realized by applying the bias voltage, (3) by introducing the atmospheric gas, and the like.

  As the base material for forming the hard film of the present invention, the above-mentioned cold tool steel, hot tool steel, and high speed tool steel (for example, SKH51, SKD11, SKD61, etc.) can be cited as representative examples. It can also be applied to hard alloys and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

[Example 1]
A target made of various alloys or metals is arranged on the cathode of the apparatus (AIP apparatus) shown in FIG. 1, and a superalloy chip and a sliding test disk (as a processing object 5) on a rotating rotating disk 2 ( SKD11 manufactured: φ55 mm × 5 mm thickness, single-sided mirror polishing) was attached, and the chamber 1 was evacuated. Thereafter, the temperature of the object 5 is heated to 500 ° C. by the heaters 7a to 7d disposed in the chamber 1, and nitrogen gas (N ₂ —CH ₄ mixed gas in the case of a C-containing film) is introduced. The pressure in the chamber 1 was set to 2.66 Pa, arc discharge was started, and various laminated hard coatings (A layer and B layer shown in Table 1 below) were laminated on the surface of the base material (object 5). Hard film) to a thickness of about 5 μm (5000 nm). At this time, the means for forming the laminated hard film was controlled by any one of (1) to (3) described above.

  About the obtained hard film, the metal component composition in the film was measured by EPMA, and the crystal structure and Vickers hardness (load: 0.25 N, holding time: 15 seconds) of the film were investigated. Moreover, the high temperature sliding characteristic of the film was evaluated under the following conditions.

[Evaluation conditions for high-temperature sliding properties of film]
Test method: Vane on disk Disc: Disc coated with various films obtained as described above Vane: SKD11 Tip radius 10R Hardness HRC52
Vertical load: 400N
Sliding speed: 0.1 m / s
Atmospheric temperature: 500 ° C
Sliding distance: 500m
Evaluation items: Friction coefficient, wear amount of disk and vane

  In addition, the wear amount of the vane is an average value (mg) of weight reduction due to wear of the two vanes, and the wear amount on the disk side is the frictional cross section (thickness direction cross section) of the sliding mark formed on the disk. Four points were measured in the direction perpendicular to each other, and the wear volume was obtained by multiplying the peripheral length of the sliding trace.

  These results are collectively shown in Table 1 below. Sample No. No. 3, the A layer has a bias voltage of 20 V and the crystal structure is hexagonal, the B layer has a bias voltage of 80 V and the crystal structure has a cubic structure, In the sample No. 4, the A layer has a bias voltage of 80V and the crystal structure is cubic, and the B layer has a bias voltage of 20V and the crystal structure is hexagonal. In both cases (A layer and B layer), the bias voltage is 80 V and the crystal structure is cubic.

  As is clear from these results, those satisfying the requirements defined in the present invention (Sample Nos. 3-8, 10-26) all have high hardness, a small friction coefficient, and a small amount of wear. I understand that.

[Example 2]
A target made of various alloys or metals is arranged on the cathode of the apparatus (AIP apparatus) shown in FIG. 1, and a superalloy chip and a sliding test disk (as a processing object 5) on a rotating rotating disk 2 ( SKD11: φ55 mm × 5 mm thickness, single-sided mirror polishing) was attached, and the chamber 1 was evacuated. Thereafter, the temperature of the object 5 is heated to 500 ° C. with a heater (not shown) arranged in the chamber 1 and nitrogen gas (N ₂ —CH ₄ mixed gas in the case of a C-containing film) is introduced. Then, the partial pressure in the chamber was set to 2.66 Pa, arc discharge was started, and a Cr-containing underlayer as shown in Table 2 below was formed on the surface of the base material (processed object 5). The hard film (Sample Nos. 3 to 23 shown in Table 1) was formed.

  For the obtained hard coating, the metal component composition was measured in the same manner as in Example 1, and the crystal structure and Vickers hardness (load: 0.25 N, holding time: 15 seconds) of the film were investigated. Moreover, the high temperature sliding characteristic and film | membrane adhesiveness (adhesion with a base material) of a film | membrane were evaluated on condition of the following.

[Evaluation conditions for high-temperature sliding properties of film]
Test method: Vane on disk Disc: Disc coated with various films obtained as described above Vane: SKD11 Tip radius 10R Hardness HRC52
Vertical load: 500N
Sliding speed: 0.1 m / s
Atmospheric temperature: 400 ° C
Sliding distance: 1000m
Evaluation items: Friction coefficient, wear amount of disk and vane

[Coating adhesion evaluation conditions]
Test method: Scratch test Indenter: Diamond tip radius: 200 μm R
Load: Max 200N
Load increase speed: 100 N / min Scratch speed: 10 mm / min Evaluation item: Vertical load (N) of the film isolation point that can be confirmed with an optical microscope (200 times)
The higher the value, the better the adhesion of the film.

These results are collectively shown in Table 2 below. In Table 2, the sample No. in Table 1 is shown for comparison. 1 and 2 (no base layer), hard coating with VC (Sample No. 27), hard coating with (Al _0.6 V _0.4 ) N film (Sample No. 49, 50) The evaluation results were also shown.

  As is apparent from the results, those satisfying the requirements defined in the present invention (Sample Nos. 29 to 46) all have high hardness, a small coefficient of friction, and a small amount of wear. It can be seen that the adhesion to the substrate is also good (the film peeling point vertical load is large).

It is a schematic explanatory drawing which shows the structural example of the arc ion plating apparatus (AIP apparatus) for manufacturing the hard film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Turntable 3 Turntable 5 To-be-processed object (base material)
6a, 6b, 6c, 6d Arc evaporation source 7a, 7b, 7c, 7d Heater 8a, 8b, 8c, 8d Arc power source 9a, 9b, 9c, 9d Mass flow controller 10 Bias power source

Claims (12)

A hard film formed on the surface of a base material, and two or more kinds of films different from each other are laminated in one layer or two or more layers, and the film constituting each layer is a film represented by the following formula (1) A hard film formed on the surface of a base material of a jig for plastic working , characterized in that
(Al _1-abc V _a Si _b B _c ) (C _1-x N _x ) (1)
However, 0.27 ≦ a ≦ 0.9, 0 ≦ b + c ≦ 0.2, 0.1 ≦ x ≦ 1.0
[Subscripts in the formula indicate atomic ratios independent of each other] The hard film according to claim 1, wherein two or more different films are laminated in two or more layers. 3. The hard coating according to claim 1, wherein the thickness of each of the films is 2 to 100 nm, and the total thickness of the films is 3000 to 10,000 nm. The hard film according to any one of claims 1 to 3, wherein the two or more kinds of films different from each other have different compositions. The mutually different two or more kinds of film, the (1) hard skin membrane according to any of claims 1-4 the value of x is the even that different from each other in type. It is represented by the following equation (2), and the thickness is 5μm or more films, to claim 1-5 in which is formed as a base layer between the hard film and the substrate surface Hard coating as described.
M (C _1-y N _y ) (2)
However, 0 ≦ y ≦ 1.0
[M represents at least one element selected from Group 4A elements, Group 5A elements, Group 6A elements, Al, Si and B in the periodic table; y represents an atomic ratio] The hard coating according to claim 6 , wherein the M contains at least Cr and an atomic ratio of Cr in the element M is 0.3 or more. It is a hard film formed on the surface of the substrate, and the film represented by the following formula (3) and the film represented by the following formula (4) are each laminated in one layer or two or more layers. Hard coating formed on the base material surface of a jig for plastic working characterized by
(Al _1-abc V _a Si _b B _c ) (C _1-x N _x ) (3)
However, 0.27 ≦ a ≦ 0.9, 0 ≦ b + c ≦ 0.2, 0.1 ≦ x ≦ 1.0
[Subscripts in the formula indicate atomic ratios independent of each other]
M (C _1-y N _y ) (4)
However, 0 ≦ y ≦ 1.0
[M represents at least one element selected from Group 4A elements, Group 5A elements, Group 6A elements, Al, Si and B in the periodic table; y represents an atomic ratio] The hard film according to claim 8, wherein the film represented by the formula (3) and the film represented by the formula (4) are laminated in two or more layers. The hard film according to claim 8 or 9, wherein the film thickness of each film is 2 to 100 nm, and the total film thickness of each film is 3000 to 10000 nm. Wherein (4) represented by formula, and the thickness is 5μm or more films, in any one of claims 8 to 10 and is formed as a base layer between the hard film and the substrate surface Hard coating as described. The hard coating according to claim 11 , wherein at least Cr is contained as M in the underlayer, and an atomic ratio of Cr in the element M is 0.3 or more.

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