JP2013052478A - Tool coated with hard film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool coated with a hard film, which is obtained by forming a CrAlN/BN nanocomposite film on a tool base material with high adhesion strength and in which excellent coating performance that the CrAlN/BN nanocomposite film has can be suitably exhibited.SOLUTION: Since the hard film 20 is composed of at least four layers formed by alternately laminating I layers 22 each composed of a nitride or a carbonitride of AlTiCrand II layers 26 each composed of the CrAlN/BN nano composite film so that one of the I layers is formed on the surface of the tool base material 12, high adhesion strength can be obtained. Since the thickness T2 of the I layer 22 and the thickness T3 of the II layer 26 are within a range of 1-50 nm and the total thickness Ttotal is within a range of 0.1-20 μm, the excellent coating performance that the CrAlN/BN nanocomposite film of the II layer 26 has can be suitably exhibited. Since each of the thicknesses T2, T3 has an extremely thin nanolayer structure of 1-50 nm, adhesiveness is further improved and a film hardness of ≥40 GPa can be obtained.

Description

  The present invention relates to a hard-coated tool, and more particularly to a hard-coated tool excellent in high heat resistance, chemical stability at high temperatures, wear resistance, welding resistance, and the like.

  2. Description of the Related Art Hard coating coated tools in which the surface of a tool base material such as high speed tool steel or cemented carbide is coated with a hard coating are widely known. The tool described in Patent Document 1 is an example, and it has been proposed to provide TiBN as a hard coating.

JP 2004-1215 A

  By the way, in recent years, from the viewpoint of environmental protection, it has been switched from wet cutting to dry cutting, but the burden on the tool becomes large, and the cutting edge temperature becomes several hundred degrees Celsius or more especially in high-speed cutting. However, a sufficient tool life cannot always be obtained, and there is a demand for a hard-coated tool that is more excellent in heat resistance, chemical stability at high temperatures, wear resistance, welding resistance, and the like.

  On the other hand, the applicant of the present application described in Japanese Patent Application No. 2010-056087 filed earlier is a composite film (CrAlN / BN nanocomposite film) in which a nitride phase and a BN phase of CrAlN are mixed three-dimensionally as a hard film. Proposed to use. This CrAlN / BN nanocomposite coating has a nanocomposite structure that surrounds CrAlN microcrystals with an amorphous BN phase, which not only prevents dislocation generation and migration, but also prevents intergranular slippage. An ultra-high hardness having a plastic hardness of about 35 GPa or more can be obtained. In addition to the extremely high heat resistance and characteristics such as better welding resistance than chemical stability, it has unique characteristics such as self-curing property that the plastic hardness is higher than that immediately after film formation by heating in air. Also have. However, when such a CrAlN / BN nanocomposite coating is directly provided on the surface of a tool base material such as high-speed tool steel or cemented carbide, there is a problem that the expected performance cannot always be obtained due to poor adhesion. there were.

  The present invention has been made in the background of the above circumstances. The object of the present invention is that the CrAlN / BN nanocomposite coating is provided on the tool base material with high adhesion strength, and the CrAlN / BN nanocomposite coating has. An object is to appropriately obtain excellent heat resistance, chemical stability at high temperature, wear resistance, welding resistance, and the like.

In order to achieve this object, the first invention provides a hard coating tool whose surface is coated with a hard coating, in which (a) Al _a Ti _b Cr _c [where a, b, c are atomic ratios, respectively] 0.3 ≦ a ≦ 0.7, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.7, and a + b + c = 1], or an I layer comprising (b) CrAlN II layer which is a composite film in which a nitride phase and a BN phase are three-dimensionally mixed, and (c) the I layer is provided on the surface of the tool base material, and the I layer and the While the hard coating is formed by alternately laminating four or more II layers, (d) the layer thickness of the I layer provided on the surface of the tool base material is in the range of 10 nm to 500 nm, and others The thickness of each of the I layer and the II layer is in the range of 1 nm to 50 nm, and the total film thickness of the entire coating is 0.1 μm. Characterized in that it is in the range of 20 [mu] m.

The second invention is a hard film coated tool whose surface is coated with a hard film. (A) Al _a Ti _b Cr _c [where a, b, c are atomic ratios, 0.3 ≦ a ≦ 0 0.7, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.7, and a + b + c = 1], an I layer composed of nitride or carbonitride, and (b) a nitride phase composed of CrAlN and a BN phase; And (c) the I layer is provided on the surface of the tool base material, and the II layer is the outermost layer. While the hard film is formed by alternately laminating four or more I layers and II layers, (d) the layer thickness of the I layer provided on the surface of the tool base material is within a range of 10 nm to 500 nm. The layer thickness of the II layer excluding the other I layer and the outermost layer is within the range of 1 nm to 50 nm, The thickness is being in the range of 0.1Myuemu～20myuemu.

  According to a third invention, in the hard film coated tool of the first or second invention, at least one of the I layers provided on the surface of the tool base material is formed by an arc ion plating method. Features.

  According to a fourth invention, in the hard film-coated tool according to any one of the first to third inventions, the II layer is formed by a sputtering method.

  5th invention WHEREIN: In the hard film coating tool in any one of 1st invention-4th invention, the content rate of the said BN phase in the said II layer is in the range of 8 vol (volume)%-28 vol%. Features.

  A sixth invention is the hard coating tool according to any one of the first to fifth inventions, wherein the BN phase content continuously increases or decreases between the I layer and the II layer. A layer is provided.

  A seventh invention is the hard coating coated tool according to any one of the first to sixth inventions, wherein the I layer provided on the surface of the tool base material is formed by an arc ion plating method, and the other I layers The II layer is formed by sputtering.

  The eighth invention is the hard coating coated tool according to any one of the first to sixth inventions, wherein all the I layers including those provided on the surface of the tool base material are formed by an arc ion plating method. In addition, all the II layers are formed by a sputtering method.

According to the hard coat coated tool of the first invention, the I layer made of Al _a Ti _b Cr _c nitride or carbonitride is provided on the surface of the tool base material, and the I layer and the CrAlN nitride phase Since the hard film is composed of four or more layers, which are composed of a composite film (CrAlN / BN nanocomposite film) in which the BN phase and BN phase are mixed three-dimensionally, the hard film has high adhesion strength. Can be provided on the tool base material. In particular, since the layer thickness of the I layer provided on the surface of the tool base material is in the range of 10 nm to 500 nm, it is possible to appropriately improve the adhesion strength while ensuring a predetermined film hardness.

  Further, the layer thicknesses of the other I layer and II layer excluding the I layer on the surface of the tool base material are all in the range of 1 nm to 50 nm, and the total film thickness of the entire coating is in the range of 0.1 μm to 20 μm. Therefore, the excellent heat resistance, chemical stability at high temperature, wear resistance, welding resistance, etc., possessed by the CrAlN / BN nanocomposite coating constituting the II layer can be obtained appropriately. In addition, the tool life at high loads such as dry machining and high-efficiency machining is improved, and the surface roughness is improved by suppressing welding. In particular, since the layer thicknesses of the alternately stacked I layer and II layer have an extremely thin nanolayer structure in the range of 1 nm to 50 nm, their adhesion is further improved and the thickness exceeds about 40 GPa or more. High hardness of the coating can be obtained, and durability such as wear resistance is further improved.

  The hard coat coated tool of the second invention is constructed in the same manner as the first invention except that the outermost layer of the hard coat is composed of the II layer and the layer thickness of the outermost layer is not particularly specified. Therefore, substantially the same effect as the first invention can be obtained. In addition, the outermost layer of the hard coating is composed of the II layer, and since the outermost layer II can be formed with a thickness exceeding 50 nm, the CrAlN / BN constituting the II layer Performances such as excellent heat resistance, chemical stability at high temperatures, wear resistance, and welding resistance of the nanocomposite film can be obtained more appropriately.

  In the third invention, since at least the I layer provided on the surface of the tool base material is formed by the arc ion plating method, higher adhesion strength can be obtained. That is, since the ionization rate of the arc ion plating method is higher than that of the sputtering method, the I layer can be provided with a uniform film quality on the cutting edge of a three-dimensional tool and the film can be formed with high adhesion strength. It is.

  In the fourth invention, since the II layer is formed by a sputtering method, it is possible to appropriately provide a CrAlN / BN nanocomposite film constituting the II layer, heat resistance and chemical stability at high temperature. Performances such as wear resistance and welding resistance can be appropriately obtained.

  In the fifth invention, since the content of the BN phase in the II layer is in the range of 8 vol% to 28 vol%, the heat resistance and high temperature of the CrAlN / BN nanocomposite coating constituting the II layer are high. Performances such as chemical stability, wear resistance, and welding resistance can be appropriately obtained.

  In the sixth invention, since the transition layer in which the content of the BN phase continuously increases or decreases is provided between the I layer and the II layer, the adhesion between the I layer and the II layer is further enhanced. As a result, the adhesion strength of the hard coating is further improved.

  In the seventh invention, the I layer provided on the surface of the tool base material is formed by the arc ion plating method, and the other I and II layers are all formed by the sputtering method. A film can be easily provided.

  In the eighth invention, all of the I layers including those provided on the surface of the tool base material are formed by the arc ion plating method, and all the II layers are formed by the sputtering method. The presence of the I layer formed by the Ting method improves the adhesion of each layer and further improves the adhesion strength of the hard coating. Even when the I layer and the II layer are alternately formed by the arc ion plating method and the sputtering method as described above, for example, by using a composite film forming apparatus including both an arc ion plating evaporation source and a sputtering evaporation source. A film can be easily formed.

1A and 1B are views showing a ball end mill according to an embodiment of the present invention, in which FIG. It is an expanded sectional view of the surface vicinity of the provided blade part. It is a top view explaining schematic structure of the composite film-forming apparatus provided with both the arc ion plating evaporation source and sputtering evaporation source which can form the hard film of FIG. 1 suitably. It is a figure which shows some other examples of the laminated structure of a hard film, All are sectional drawings corresponding to FIG.1 (c). It is a figure which shows the result of having investigated the relationship between the plastic hardness Hpl of the CrAlN / BN nanocomposite film in various gas atmospheres, and the heat processing temperature Ta. It is a figure which shows the result of having investigated the relationship between the effective Young's modulus E ^* of the CrAlN / BN nanocomposite film in various gas atmospheres, and the heat processing temperature Ta. It is the figure which compared and showed the result of the elemental analysis by GDS before and after heat processing about a CrAlN / BN nanocomposite film. It is a figure which shows the result of having investigated the relationship between the content rate of the BN phase, and plastic hardness Hpl about a CrAlN / BN nanocomposite film. It is a figure which shows the result of having investigated the change rate of the plastic hardness with respect to heat processing temperature Ta about several types of film from which the content rate of the BN phase differs about a CrAlN / BN nanocomposite film. It is a figure which shows the result of having investigated the film hardness about the multiple types of sample (test product) containing this invention product. It is a figure explaining the test conditions at the time of performing a durability test using sample No1, No2, No5, and No12 of FIG. It is a figure which shows the test result which performed the durability test according to the test conditions of FIG. It is a figure which shows the test conditions and test result of the scratch test performed using three types of test products of sample No2, No9, and No10 of FIG.

  INDUSTRIAL APPLICABILITY The present invention is suitably applied to hard coatings provided on the surfaces of various processing tools such as end mills, taps, and rotary cutting tools such as drills, non-rotating cutting tools such as cutting tools, and rolling tools. . Suitable tool base materials for hard coating coated tools include cemented carbide, high speed tool steel, tool steel, die steel, cermet, ceramics, polycrystalline diamond (PCD), single crystal diamond, polycrystalline CBN, and single crystal CBN. However, other tool materials can be employed.

As a means for forming the hard coating, a PVD method (physical vapor deposition method) such as an arc ion plating method, a sputtering method, or a PLD (Puls LASER Deposition) method is preferably used. For Al _a Ti _b Cr _c and CrAl alloys constituting the hard coating, for example, a metal target having the same composition may be prepared, and for the BN phase constituting the II layer, for example, B such as a BN sintered body is contained. What is necessary is just to prepare the target to do. About supply of C (carbon), any method of reaction gas (hydrocarbon gas etc.) or a solid target (C target, C containing target) may be sufficient. N (nitrogen) can be added by supplying the reaction gas.

  The hard-coated tool of the present invention is suitably used when used under high-temperature processing conditions such as dry cutting at high speeds and high loads, and excellent durability (tool life) can be obtained. Of course, it is also possible to use it under the processing conditions where welding resistance, wear resistance and heat resistance are not so required, for example, in cutting using a cutting fluid.

The nitride or carbonitride of Al _a Ti _b Cr _c constituting the I layer contains at least Al in an atomic ratio of 0.3 to 0.7, and one of Ti and Cr is 0, It does not need to contain. That is, not only AlTiCr but also CrAl or TiAl can be employed. Further, it may be _a carbonitride containing both C and N (Al _a Ti _b Cr _c CN) or a nitride containing only N (Al _a Ti _b Cr _c N). The Al and Cr contribute to the improvement of adhesion with the CrAlN / BN nanocomposite coating having a CrAlN nitride phase, and Ti contributes to the strength enhancement of the coating.

  The CrAlN / BN nanocomposite coating that constitutes the II layer, that is, a composite film in which a nitride phase composed of CrAlN and a BN phase are three-dimensionally mixed, is a nanostructure in which an amorphous BN phase surrounds a CrAlN microcrystal. Since it has a composite structure and not only prevents dislocation generation and movement, but also does not easily cause grain boundary sliding, an ultra-high hardness with a plastic hardness of about 35 GPa or more can be obtained. In addition to the extremely high heat resistance and characteristics such as better welding resistance than chemical stability, it has unique characteristics such as self-curing property that the plastic hardness is higher than that immediately after film formation by heating in air. Also have.

  The CrAlN / BN nanocomposite film includes a case where oxygen or other impurity element metal is contained. In particular, oxygen is usually contained in the target material or the like in an amount of less than 1 mass%, and is also contained in the gas remaining in the vacuum film forming apparatus. In addition to Cr and Al, transition metal elements such as Mo, W, Ti, and Zr, Si, and the like may be included as impurities.

The ratio of the atomic ratio of Cr to Al in CrAlN constituting the CrAlN / BN nanocomposite coating is desirably in the range of about 3: 7 to 7: 3. Assuming that the ratio of the atomic ratio of Cr and Al is 5: 5, instead of Cr, Cr and V, Mo, Nb, Ta, etc. (on the oxide generation free energy diagram of B) It is presumed that the same self-curing property can be obtained even when a material having a ratio of atomic ratio such as Cr> V is used. That is, CrAlN is preferably Cr _d Al _e N (where d and e are atomic ratios of 0.3 ≦ d ≦ 0.7, 0.3 ≦ e ≦ 0.7, d + e = 1), and Also included is an embodiment in which the metal Me on the oxide formation free energy diagram of B, such as V, Mo, Nb, and Ta, is contained instead of Cr at a ratio smaller than 1/2 of the atomic ratio d of Cr.

  In the CrAlN / BN nanocomposite coating, the plastic hardness decreases when the BN phase content exceeds 28 vol%, and the plastic hardness decreases by heat treatment when the content is less than 8 vol%. The vol% range is appropriate.

  The total film thickness of the hard coating is in the range of 0.1 μm to 20 μm, but if it is less than 0.1 μm, sufficient performance as a hard coating cannot be obtained, and if it exceeds 20 μm, the cutting edge of the cutting tool is rounded, etc. As a result, the tool performance may be impaired. This total film thickness is a film thickness from the surface of the tool base material to the outermost surface of the hard coating, and when the transition layer is provided between the I layer and the II layer, the total film thickness includes the transition layer.

  The I layer except the I layer on the surface of the tool base material and all the II layers, or the II layer excluding the outermost layer have a nanolayer structure in which the layers are alternately stacked with a layer thickness of 1 nm to 50 nm. However, both layer thicknesses may be substantially the same (equal) or different from each other. For example, film formation can be performed such that the layer thickness ratio of the I layer and the II layer is 1: 1, 1: 2, 1: 3, 3: 1, 2: 1, etc. by changing the use output and quantity of the target. . Further, by changing the target output, it is possible to form a film so that the thickness of each layer increases or decreases from the lowermost layer to the outermost layer. If the layer thickness exceeds 50 nm, the effect of improving the film hardness cannot be obtained sufficiently, and if it is less than 1 nm, the performance of each film cannot be obtained properly and the film thickness is difficult to control, so the range is from 1 nm to 50 nm. The inside is appropriate. These I layer and II layer are alternately laminated at least 4 layers or more, but it is desirable to provide 10 layers or more or 50 layers or more.

  The thickness of the outermost layer composed of the II layer in the second invention is not limited to the range of 1 nm to 50 nm so as to obtain a predetermined film performance, and is determined independently from the other layers. However, in order not to impair the effect of improving the film hardness by the nanolayer structure, for example, it is preferably in the range of 1 nm to 200 nm, or in the range of about 1 nm to 100 nm. In the second invention, the outermost layer is composed of the II layer. However, since the I layer and the II layer are both extremely thin when implementing the first invention, either the I layer or the II layer may be the outermost layer. .

  When the thickness of the I layer provided on the surface of the tool base material exceeds 500 nm, the film hardness decreases, and when the thickness is less than 10 nm, the effect of improving the adhesion strength cannot be sufficiently obtained. Is appropriate.

  In the sixth invention, a transition layer in which the content of the BN phase continuously increases or decreases is provided between the I layer and the II layer, but a mixed layer in which only the I phase and the II phase are mixed is provided. It can also be provided. Between the I layer and the II layer, a mixed layer is formed simply by switching between the I layer and the II layer. However, by forming both layers simultaneously for a predetermined time, a predetermined thickness is obtained. It is also possible to provide a mixed layer. The transition layer gradually increases the BN phase at the transition portion from the I layer to the II layer, and gradually decreases the BN phase at the transition portion from the II layer to the I layer. Such a transition layer can be formed by continuously changing the output of the B-containing target. The thickness of the transition layer is set as appropriate. For example, it is desirable that the thickness of the transition layer is equal to or thinner than the thinner one of the upper and lower I layers and II layers.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are views for explaining a ball end mill 10 which is an example of a hard film coated tool to which the present invention is applied. FIG. 1A is a front view seen from a direction perpendicular to the axis, and FIG. It is the enlarged bottom view seen from the figure of a) of the figure, and the tool base material 12 comprised with the cemented carbide is provided with the blade part 14 integrally with the shank continuously. The blade portion 14 is provided with a pair of outer peripheral blades 16 and a ball blade 18 symmetrically with respect to the axis as cutting edges, and the surface of the blade portion 14 is coated with a hard coating 20. By being driven to rotate around the axis, cutting is performed by the outer peripheral edge 16 and the ball edge 18. The hatched portions in FIGS. 1A and 1B represent the hard coating 20, and FIG. 1C is a cross-sectional view of the vicinity of the surface of the blade portion 14 coated with the hard coating 20.

As is clear from FIG. 1 (c), the hard coating 20 has a laminated structure in which four or more I layers 22 and II layers 26 are alternately laminated, and in this embodiment, has a multilayer structure in which 50 or more layers are laminated. . The I layer 22 is Al _a Ti _b Cr _c [where a, b, c are atomic ratios, 0.3 ≦ a ≦ 0.7, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.7, respectively. , And a + b + c = 1], and the I layer 22 is provided on the surface of the tool base 12. The II layer 26 is a CrAlN / BN nanocomposite film that is a composite film in which a nitride phase and a BN phase composed of CrAlN are three-dimensionally mixed. CrAlN is Cr _d Al _e N [where d and e are atoms The ratio is 0.3 ≦ d ≦ 0.7, 0.3 ≦ e ≦ 0.7, d + e = 1]. In this embodiment, the outermost layer of the hard coating 20 is composed of the II layer 26. Yes. The I layer 22 and the II layer 26 are alternately stacked so as to be in contact with each other, and a mixed layer in which both components are mixed is formed at a boundary portion between them.

  The layer thickness T1 of the lowermost I layer 22 provided on the surface of the tool base 12 is appropriately determined within a range of 10 nm to 500 nm, the layer thickness T2 of the other I layer 22, and all the II layers. Each of the layer thicknesses T3 of 26 is appropriately determined within a range of 1 nm to 50 nm. Further, the layer thicknesses T2 and T3 are substantially equal to each other, and the total film thickness Ttotal of the entire hard coating 20 is in the range of 0.1 μm to 20 μm.

  Such a hard coating 20 can be formed by using, for example, a composite film forming apparatus 40 having both an arc ion plating evaporation source and a sputtering evaporation source schematically shown in FIG. The composite film forming apparatus 40 provided with both the arc ion plating evaporation source and the sputtering evaporation source is provided with both the arc ion plating evaporation source 42 and the sputtering evaporation source 44, and is disposed in a common chamber 46. The workpiece 48 can be coated by both arc ion plating and sputtering. The workpiece 48 is the tool base material 12 in a state before being coated with the hard coating 20, and is placed on the three first rotary tables 50 and rotated, and is revolved in the chamber 46 by the second rotary table 52. The arc ion plating evaporation source 42 and the sputtering evaporation source 44 are passed through. In FIG. 2, a total of four arc ion plating evaporation sources 42 and sputtering evaporation sources 44 are arranged around the chamber 46 at intervals of 90 °, but these evaporation sources 42 and 44 are arranged one by one. It may be provided.

The arc ion plating evaporation source 42 is for forming the I layer 22 by an arc ion plating method, and includes an Al _a Ti _b Cr _c metal target 54. The sputtering evaporation source 44 is for forming the II layer 26 by a sputtering method, and includes a Cr _d Al _e metal target 56 and a B-containing target 58 such as a BN sintered body target. Further, N (nitrogen) of nitride or carbonitride can be added by supplying a reaction gas (nitrogen gas), and a reaction gas (hydrocarbon gas, etc.) of C (carbon) of carbonitride. Alternatively, it can be added by any method of a solid target (C target, C-containing target). Argon gas is used as the sputtering gas, and a predetermined bias voltage is applied to the work 48 from a bias power source.

In this embodiment, all the I layers 22 are formed by the arc ion plating method using the arc ion plating evaporation source 42, and all the II layers 26 are formed by the sputtering method using the sputtering evaporation source 44. Is done. However, the I layer 22 can also be formed by sputtering using the sputtering evaporation source 44 by disposing the Al _a Ti _b Cr _c metal target 54 also in the sputtering evaporation source 44. For example, the lowermost I layer 22 provided in contact with the surface of the tool base material 12 is formed by an arc ion plating method using an arc ion plating evaporation source 42 so as to obtain excellent adhesion, The upper I layer 22 may be formed by sputtering using a sputtering evaporation source 44. The I layer 22 is a nitride or carbonitride of Al _a Ti _b Cr _c and contains the same component (Al or Cr) as the nitride phase of Cr _d Al _e constituting the II layer 26. The affinity with the II layer 26 is high, and sufficient adhesion can be secured even when formed by a sputtering method. When the Al _a Ti _b Cr _{c of} the I layer 22 is the same component as the Cr _d Al _e of the II layer 26, that is, when the atomic ratio a = e, c = d and b = 0, the common metal target 56 is formed. The I layer 22 can be formed by using this.

  The hard coating 20 of this embodiment is laminated so that the I layer 22 and the II layer 26 are in contact with each other. However, like the hard coating 30 shown in FIG. Transition layers 24, 28 may be provided between the layer 26. The transition layers 24 and 28 are the same CrAlN / BN nanocomposite coating as the II layer 26, and the content of the BN phase is continuously changed, and the first transition is laminated on the I layer 22. In the layer 24, the content of the BN phase is continuously increased from 0 vol%, and the content is the same as that of the II layer 26 in the surface portion that is a boundary with the II layer 26. In the second transition layer 28 laminated on the II layer 26, the content of the BN phase is continuously reduced from the same content as that of the II layer 26, and at the surface portion that is the boundary with the I layer 22 0 vol%. Such transition layers 24 and 28 can be formed by the sputtering method using the sputtering evaporation source 44 similarly to the II layer 26, and change the output of the B-containing target 58 such as a BN sintered body target. Can be formed. The thicknesses of these transition layers 24 and 28 are substantially the same as or smaller than those of the I layer 22 and the II layer 26. In this embodiment, the layer thicknesses T2 and T3 of the I layer 22 and the II layer 26 are substantially the same. The thickness is the same. The total thickness Ttotal of the hard coating 30 including the transition layers 24 and 28 is in the range of 0.1 μm to 20 μm, similar to the hard coating 20.

  3B is a case where the first transition layer 24 is provided only between the lowermost I layer 22 and the II layer 26 thereon. Further, the hard coating 34 shown in FIG. 3C is different from the hard coating 20 in that the thickness T4 of the II layer 26 constituting the outermost layer is different from that of the hard coating 20 so that a predetermined coating performance can be obtained. When the thickness is larger than the layer thickness T3 of the II layer 26, the thickness is appropriately determined within the range of 1 nm to 200 nm. In any of the hard coatings 32 and 34, the total total film thickness Ttotal is in the range of 0.1 μm to 20 μm. In addition, regarding the hard films 30 and 32, a mixed layer may be provided instead of the transition layers 24 and 28. The thickness of the mixed layer may be the same as the layer thicknesses T2 and T3 of the I layer 22 and the II layer 26, but may be thinner.

Next, the results of examining the film performance of the CrAlN / BN nanocomposite film constituting the II layer 26 will be described. Here, a sample was used in which a CrAlN / BN nanocomposite coating was directly provided with a target film thickness of 3.5 μm on a high-speed steel substrate by a sputtering method at a heating temperature of 350 ° C. The Cr and Al atomic ratios d and _e of the Cr _d Al _e N phase of the CrAlN / BN nanocomposite coating are both 0.5, and the BN phase content is the output of the B-containing target 58 such as a BN sintered body target. It can change suitably by changing. The content of the BN phase can be measured using, for example, a wavelength dispersion type EPMA (Electron Probe MicroAnalyser).

  FIG. 4 is for evaluating self-curing property and heat resistance (oxidation resistance) of a CrAlN / BN nanocomposite film having a BN phase content of 18 vol%, and has a plastic hardness Hpl of various atmospheres (atmospheres). , Nitrogen, argon) is a graph showing how the heat treatment temperature Ta changed under different conditions, and after heating at each temperature for 1 hour, the plastic hardness Hpl was measured at room temperature. For the plastic hardness Hpl, use an ultra micro indenter, select the maximum load so that the penetration depth of the indenter into the film is approximately 1/10 or less of the film thickness, and select the indenter from the tangent line of the unloading curve. A known Oliver method was used to calculate the plastic hardness Hpl by obtaining the penetration depth and converting it to the contact area. As is apparent from FIG. 4, in the case of nitrogen and argon, the plastic hardness Hpl immediately after film formation is substantially maintained up to a heating temperature of 800 ° C., whereas in the case of air, the plastic hardness Hpl is about 40 GPa immediately after film formation. The plastic hardness Hpl that has been present increases rapidly at 600 ° C., exceeds 50 GPa at 700 ° C. and 800 ° C., and decreases to less than 20 GPa at 900 ° C. at once. This shows that the CrAlN / BN nanocomposite coating has almost no self-curing property in a non-oxidizing atmosphere, but exhibits a self-curing property in an oxidizing atmosphere.

5, using a CrAlN / BN nanocomposite coating content of 18 vol% of the same BN phase and 4, the effective Young's modulus E ^* various atmosphere (air, nitrogen, argon) difference in heat treatment temperature Ta under It is a graph which shows how it changed by. The effective Young's modulus E ^* is E / (1-n ² ), and since the Poisson's ratio (n) of the film is unknown, the value obtained by dividing the Young's modulus E by (1-n ² ) was used. From the results shown in FIG. 5, in the case of nitrogen and argon, the effective Young's modulus E ^* immediately after film formation is substantially maintained up to 800 ° C., whereas in the atmosphere, the effective Young's modulus was about 350 GPa immediately after film formation. It can be seen that the rate E ^* rises sharply at the boundary of 600 ° C., reaches about 480 GPa at 700 ° C., about 440 GPa at 800 ° C., and decreases to about 260 GPa at 900 ° C. at once.

FIG. 6 shows the results of elemental analysis by GDS (Glow Discharge Spectrometer) for the CrAlN / BN nanocomposite coating with a BN phase content of 18 vol% as described above before and after heat treatment. It is the figure shown by comparing with. The sample after the heat treatment is a sample heated in the atmosphere at a heat treatment temperature Ta = 800 ° C. for 1 hour and then returned to room temperature. As is apparent from FIG. 6, oxygen (O) increases in the surface layer portion of 0.2 μm or less after the heat treatment as compared with before the heat treatment. Therefore, considering FIGS. 4 and 5 together, it is considered that the film hardness (plastic hardness Hpl) and the effective Young's modulus E ^* are improved by oxidizing the surface layer to some extent.

  FIG. 7 is a diagram showing the results of examining the relationship between the BN phase content and the plastic hardness Hpl of the CrAlN / BN nanocomposite coating. In this case, the plastic hardness Hpl is a value after the heat treatment, and when the content of the BN phase exceeds 28 vol%, it decreases to 30 GPa or less, so 28 vol% or less is desirable. FIG. 8 is a graph showing the results of examining the rate of change in plastic hardness with respect to the heat treatment temperature Ta for a plurality of types of coatings having different BN phase contents for a CrAlN / BN nanocomposite coating, immediately after film formation ( It is obtained by setting the plastic hardness Hpl before heat treatment to 100%. In any case, the heat treatment by heating in the atmosphere shows that when the BN phase content is 0 vol%, the plastic hardness Hpl decreases monotonously, whereas when it contains the BN phase, it tends to be maintained or slightly increased. . Although illustration is omitted, when the BN phase content is 7 vol%, the increasing tendency of the plastic hardness Hpl is small, and when it is 8 vol% or more, the plastic hardness Hpl increases remarkably. From these results shown in FIGS. 7 and 8, the content of the BN phase is preferably in the range of 8 vol% to 28 vol%.

  On the other hand, FIG. 9 shows the present invention provided with a hard coating 20 in which 50 layers or more are alternately laminated so that the I layer 22 and the II layer 26 (T2 = T3) are in contact with each other as in the ball end mill 10 of FIG. It is the figure which showed the result of having investigated the film hardness (plastic hardness Hpl) about several types of test goods containing these hard film coating tools with the film structure of each test goods. In FIG. 9, comparative samples No. 5 to No. 7 are hard coatings having a laminated structure, but the layer thicknesses T2 and T3 of the I layer 22 and the II layer 26 exceed 50 nm. Sample No8 as a comparative product is different from the product of the present invention in that the layer thickness T1 of the lowermost I layer 22 on the surface of the tool base material 12 exceeds 500 nm. Sample No9 has a layer thickness T1 of 10 nm. This is different from the product of the present invention. Sample No. 10 is a single-layer hard coating consisting only of the II layer 26 made of a CrAlN / BN nanocomposite coating. Sample No. 11 differs from the present invention in that the I layer 22 does not contain Al. The conventional samples No. 12 and No. 13 are different from the product of the present invention in that none of the samples No. 12 and No. 13 includes the II layer 26 made of a CrAlN / BN nanocomposite coating. The “total film thickness” is the total film thickness Ttotal from the surface of the tool base material 12 to the coating surface, and the “layer thickness of the I layer immediately above the base material” is the layer thickness T1. “Number of layers” is the number of I layers 22 and II layers 26. When both the I layer 22 and the II layer 26 are provided, the II layer 26 is the outermost layer when the number is even, and the I layer 22 is the highest when the number is odd. It becomes the surface layer. The “film hardness” is the plastic hardness Hpl, which is a value at the time of film formation, and was measured using the ultra-micro indenter. The layer thicknesses T2 and T3 of the I layer 22 and the II layer 26 are obtained by subtracting the “layer thickness of the I layer immediately above the base material” from the “total film thickness” and dividing by (“number of layers” −1). Is required.

  As is clear from FIG. 9, all of the products of the present invention (samples No. 1 to No. 4) had an ultra-high hardness of 40 GPa or more. On the other hand, the film hardness of the comparative products (samples Nos. 5 to 7) in which the layer thicknesses T2 and T3 of the I layer 22 and the II layer 26 exceed 50 nm are 34 to 36 GPa, which is 5 GPa or more lower than the products of the present invention. The film thickness of the comparative product (sample No. 8) having the “layer thickness of the I layer immediately above the base material”, that is, the layer thickness T1 of 800 nm is 38 GPa, which is lower than the product of the present invention. The comparative product (sample No. 9) having a layer thickness T1 of 5 nm has a coating hardness of 43 GPa, and a coating hardness comparable to that of the present invention product is obtained. However, as is apparent from the scratch test of FIG. Cannot be obtained. Other comparative products and conventional products (sample Nos. 10 to 13) all have a coating hardness of less than 40 GPa, which is lower than the product of the present invention.

  FIG. 10 is a diagram illustrating test conditions when a durability test is performed using two test products (samples No. 1, No. 2, No. 5, and No. 12) of FIG. 9, and FIG. 11 shows the test results. FIG. (A) in FIG. 10 shows the test conditions. The tool used is a cemented carbide alloy base tool 12 with a two-blade, R = 0.5 mm ball end mill, and the work material is JIS standard SKD61 (40HRC) [alloy. Tool steel], cutting speed is 126 m / min, feed rate is 0.016 mm per tooth, cutting method is pocket machining, axial cutting depth ap = 0.05 mm, pick feed pf = 0.1 mm, cutting fluid is air blow The cutting time until the flank wear width of the ball blade 18 reached 0.05 mm was examined. The pocket size at the time of pocket processing is as shown in FIG. 10 (b), and a spiral feed of pick feed pf = 0.1 mm is applied to a square processed portion having a vertical width of 17.6 mm and a horizontal width of 17.6 mm. In addition, a cutting process is performed along with a taper angle of 3 ° and a final processing depth of 1 mm is dug down.

  As is apparent from the test results in FIG. 11, the products of the present invention (samples No. 1 and No. 2) can be cut for 200 minutes or more, and are more durable than the conventional product (sample No. 12) of about 60 minutes. (Abrasion resistance) is greatly improved. In addition, the comparative product (sample No. 5) in which the layer thicknesses T2 and T3 of the I layer 22 and the II layer 26 exceed 50 nm is about 150 minutes, and the inventive product having a nanolayer structure of 50 nm or less is superior in durability by 40% or more. Sex is obtained.

  FIG. 12 shows a scratch test on the adhesion strength of the hard coating, using a total of three types of test products of the present invention (sample No. 2) and comparative products (sample No. 9 and No. 10) among the test products of FIG. It is a figure explaining a result. In this scratch test, when the diamond cone is pressed against the specimen and scratched, the pressing load (N) is increased to detect acoustic emission (AE) that occurs when the coating breaks or peels off. The load when the detection signal suddenly rose was measured as the adhesive force. As shown in (a), the test conditions are a continuous load type in which the pressing load is continuously increased at a load speed of 400 N / min and a scratch speed of 10 mm / min. (B) in FIG. 12 shows the test results. The adhesive strength of the product of the present invention (sample No. 2) was 98 N, while the comparative product (sample No. 9) having a layer thickness T1 of 5 nm was 79 N. It is about 20N lower than Further, the comparative product (sample No. 10) in which the II layer 26 is directly provided on the surface of the tool base material 12 is 10 N, and the adhesion is extremely poor.

As is clear from the above test results, according to the present invention samples No. 1 to No. 4 including the ball end mill 10 of the above example, it is composed of a nitride or carbonitride of Al _a Ti _b Cr _c. The I layer 22 is provided on the surface of the tool base material 12, and the I layer 22 and the II layer 26 composed of a composite film (CrAlN / BN nanocomposite coating) in which CrAlN and the BN phase are three-dimensionally mixed are alternately arranged. Since four or more layers are laminated to form the hard coating 20 or the like, the hard coating 20 or the like can be provided on the tool base material 12 with high adhesion strength. In particular, since the layer thickness T1 of the I layer 22 provided on the surface of the tool base material 12 is in the range of 10 nm to 500 nm, it is possible to appropriately improve the adhesion strength while ensuring a predetermined film hardness.

  Further, the layer thicknesses T2 and T3 of the other I layer 22 and the II layer 26 excluding the I layer 22 on the surface of the tool base material 12 are all in the range of 1 nm to 50 nm, and the total film thickness Ttotal of the entire film is Since it is within the range of 0.1 μm to 20 μm, the CrAlN / BN nanocomposite coating constituting the II layer 26 has excellent heat resistance, high temperature chemical stability, wear resistance, welding resistance, etc. Performance can be appropriately obtained, the tool life at high loads such as dry machining and high-efficiency machining is improved, and the surface roughness is improved by suppressing welding. In particular, since the layer thicknesses T2 and T3 of the alternately stacked I layer 22 and II layer 26 form an extremely thin nanolayer structure in the range of 1 nm to 50 nm, their adhesion is further improved. An extremely high coating hardness of about 40 GPa or more can be obtained, and durability such as wear resistance is further improved.

  Like the hard coating 34 shown in FIG. 2 (c), the outermost layer is composed of the II layer 26, and the layer thickness T4 of the outermost layer is set to other II so that a predetermined coating performance can be obtained. In the case where the layer 26 is thicker than the layer thickness T3 and has a predetermined thickness in the range of 1 nm to 200 nm, in addition to obtaining the same effect as the hard coating 20, the outermost layer II layer 26 is configured. Performances such as excellent heat resistance, chemical stability at high temperature, wear resistance, and welding resistance of the CrAlN / BN nanocomposite coating that is available can be obtained more appropriately.

  Further, if the lowest I layer 22 provided on at least the surface of the tool base material 12 is formed by the arc ion plating method, higher adhesion strength can be obtained. In other words, since the ionization rate of the arc ion plating method is higher than that of the sputtering method, the I layer 22 can be provided with a uniform film quality on the cutting edge of a three-dimensional tool and the film can be formed with high adhesion strength. It can be done.

  Further, since the II layer 26 is formed by a sputtering method, a CrAlN / BN nanocomposite film constituting the II layer 26 can be appropriately provided, and heat resistance and chemical stability at high temperatures. Performances such as wear resistance and welding resistance can be appropriately obtained.

  Further, if the content of the BN phase in the II layer 26 is in the range of 8 vol% to 28 vol%, the heat resistance and high-temperature chemistry of the CrAlN / BN nanocomposite coating that constitutes the II layer 26 Performances such as mechanical stability, wear resistance, and welding resistance are appropriately obtained, and durability is further improved.

  Further, like the hard coatings 30 and 32 shown in FIGS. 3A and 3B, the transition layer 24 in which the BN phase content continuously increases or decreases between the I layer 22 and the II layer 26. , 28 is provided, the adhesion between the I layer 22 and the II layer 26 is further enhanced, and the adhesion strength is further improved.

  Further, when the I layer 22 provided on the surface of the tool base material 12 is formed by an arc ion plating method, and the other I layer 22 and II layer 26 are all formed by a sputtering method, a multilayer structure is formed. The hard coating 20 etc. can be provided simply.

  Further, when all the I layers 22 including the lowermost I layer 22 provided on the surface of the tool base material 12 are formed by the arc ion plating method, and all the II layers 26 are formed by the sputtering method. In the presence of the I layer 22 formed by the arc ion plating method, the adhesion of each layer is improved, and the adhesion strength of the hard coating 20 and the like is further improved. Thus, even when the I layer 22 and the II layer 26 are alternately formed by the arc ion plating method and the sputtering method, the composite film forming apparatus 40 including both the arc ion plating evaporation source and the sputtering evaporation source is used. Can be easily formed.

  As mentioned above, although the Example of this invention was described in detail based on drawing, these are one embodiment to the last, and this invention is implemented in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. be able to.

  10: Ball end mill (hard coating coated tool) 12: Tool base material 20, 30, 32, 34: Hard coating 22: I layer 24: First transition layer 26: II layer 28: Second transition layer Ttotal: Total film thickness T1: Layer thickness of the I layer immediately above the base material T2: Layer thickness of the I layer other than just above the base material T3: Layer thickness of the II layer T4: Layer thickness of the outermost layer II

Claims (8)

In hard coating coated tools whose surface is coated with a hard coating,
Al _a Ti _b Cr _c [where a, b, c are atomic ratios, 0.3 ≦ a ≦ 0.7, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.7, and a + b + c = 1, respectively. An I layer comprising a nitride or carbonitride of
II layer, which is a composite film in which a nitride phase composed of CrAlN and a BN phase are three-dimensionally mixed,
While the I layer is provided on the surface of the tool base material, the I layer and the II layer are alternately laminated to form the hard coating,
The layer thickness of the I layer provided on the surface of the tool base material is in the range of 10 nm to 500 nm, and the layer thicknesses of the other I layer and II layer are both in the range of 1 nm to 50 nm. The hard coating tool characterized by having a total film thickness in the range of 0.1 μm to 20 μm. In hard coating coated tools whose surface is coated with a hard coating,
Al _a Ti _b Cr _c [where a, b, c are atomic ratios, 0.3 ≦ a ≦ 0.7, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.7, and a + b + c = 1, respectively. An I layer comprising a nitride or carbonitride of
II layer, which is a composite film in which a nitride phase composed of CrAlN and a BN phase are three-dimensionally mixed,
The hard coating is configured by alternately laminating four or more layers of the I layer and the II layer so that the I layer is provided on the surface of the tool base material and the II layer is the outermost layer. While being
The thickness of the I layer provided on the surface of the tool base material is in the range of 10 nm to 500 nm, and the thickness of the II layer excluding the other I layer and the outermost layer is in the range of 1 nm to 50 nm. The hard film-coated tool, wherein the total film thickness of the entire film is in the range of 0.1 μm to 20 μm. The hard coating coated tool according to claim 1 or 2, wherein at least one of the I layers provided on the surface of the tool base material is formed by an arc ion plating method. The hard coating tool according to any one of claims 1 to 3, wherein the II layer is formed by a sputtering method. The hard film-coated tool according to any one of claims 1 to 4, wherein the content of the BN phase in the II layer is in the range of 8 vol% to 28 vol%. The transition layer in which the content of the BN phase continuously increases or decreases is provided between the I layer and the II layer. The hard coating tool described. The I layer provided on the surface of the tool base material is formed by an arc ion plating method, and the other I layer and the II layer are all formed by a sputtering method. The hard film coating tool according to any one of 1 to 6. The I layer including all those provided on the surface of the tool base material is formed by an arc ion plating method, and the II layer is formed by a sputtering method. The hard film coating tool according to any one of 1 to 6.

Images