JP2020152983A - Coating cutting tool and method of manufacturing the same - Google Patents

Abstract

To provide a coating cutting tool with high performance that exhibits superior heat resistance and lubricity, and a method of manufacturing the same.SOLUTION: The present invention relates to a coating cutting tool that is a coating cutting tool which has a hard coating formed on a base material, where the hard coating has a composition represented by (AlxCr1-x-y-zByRuz)N1-p-qOpCq (where x, 1-x-y-z, y, z, 1-p-q, and p and q are respectively numbers satisfying 0.35≤x≤0.75, 0.01≤y≤0.1, 0.005≤z≤0.05, 0.002≤p≤0.010, and 0≤q≤0.03), and an X-ray diffraction pattern has a single structure fcc.SELECTED DRAWING: Figure 3

Description

The present invention relates to a coated cutting tool exhibiting excellent heat resistance and lubricity, and a method for manufacturing the same.

For example, the following conventional techniques have been proposed regarding the stability (heat resistance) of a hard film of a coated cutting tool against frictional oxidation.

Patent No. 5419393 (Patent Document _{1), (Al a Mg b Cr c} Me d B e AX m Si k) α (N u C v O w) β [ wherein, (a + b + c + d + e + m + k) = α, (u + v + w ) = Β, (α + β) = 100 and 40 ≦ α ≦ 60, and Me is at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W. , AX are H, Li, Na, K, Rb, Cs, Fr, Be, Ca, Sr, Ba, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu , Ag, Au, Zn, Cd, Hg, Sc, Y, La, Ac and at least one element selected from the group consisting of lanthanoid elements, 0.004 ≦ m <60, 0.4 ≦ a. ≦ 58, 0.04 ≦ b ≦ 12, 18 ≦ c ≦ 42, 4 ≦ d ≦ 54, and k are 24 at the maximum. ] Is disclosed, which includes at least one first hard layer having a composition represented by.

Patent No. 5450400 (Patent Document _{2), (Al x Ti y Ru z} Me v) (N a C 1-a) ( although, Me is Si, B, W, Mo, Cr, Ta, Nb, V , Hf and Zr are at least one element selected from the group, and x, y, z, v and a are 0.45 ≦ x ≦ 0.75 and 0.2 ≦ y ≦ 0.55, respectively. It has a composition of 0.001 ≦ z ≦ 0.1, 0 ≦ v ≦ 0.2, 0.9 ≦ (x + y + z + v) ≦ 1.1 and 0.8 ≦ a ≦ 1.0). The hard material coating is disclosed.

Japanese Patent Application Laid-Open No. 2005-330039 (Patent Document 3) describes that the composition formula: (Al _1-x Cr _x ) (N _{1- y By} ) _{z on} the surface of the base material is 0.35 ≦ x ≦ 0.65. , 0.03 ≦ y ≦ 0.3 and 0.8 ≦ z ≦ 1.2 are disclosed as wear-resistant coating members coated with a hard film.

Japanese Patent No. 5419393 Japanese Patent No. 5450400 Japanese Unexamined Patent Publication No. 2005-330039

The first hard layer of Patent Document 1 is an AlMgCrMeBAX _m SiNCO layer containing a predetermined amount of Mg and Si as essential elements, which is different from the composition of the hard film used in the present invention. The hard coatings of Patent Documents 2 and 3 are also different from the composition of the hard coating used in the present invention. Therefore, there is room for improvement in order to withstand the harsh recent cutting conditions such as high feed machining and high-speed cutting, and to sufficiently satisfy the severe problem required for cutting tools such as long life.

Therefore, an object of the present invention is to provide a new and high-performance coated cutting tool having excellent heat resistance and lubricity as compared with a conventional cutting tool coated with (AlCrB) N hard film, and a method for manufacturing the same. ..

Coated cutting tool of the present invention is made by forming a hard film on a substrate, wherein the hard film except for unavoidable impurities, the general _{formula: (Al x Cr 1-x} -y-z B y Ru z) N _{1-p-q Op} C _q (where x, 1-x-y-z, y, z, 1-p-q, p and q are atomic ratios of 0.35 ≤ x ≤ 0. 75, 0.01 ≦ y ≦ 0.1, 0.005 ≦ z ≦ 0.05, 0.002 ≦ p ≦ 0.010, and 0 ≦ q ≦ 0.03). It has a composition and is characterized in that the X-ray diffraction pattern has a single structure of fcc.

In the coating cutting tool of the present invention, the peak intensity ratio (BN) / (BO) of the BN bond and the BO bond specified by the X-ray photoelectron spectroscopy of the hard film is 0. It is preferably 4 to 1.0.

The method for manufacturing a coated cutting tool of the present invention is an AlCrBRu sintered alloy having an oxygen content of 2000 to 4000 μg / g as an arc discharge type evaporation source (target) when the coated cutting tool is manufactured by the arc ion plating method. Alternatively, an AlCrBRuC sintered alloy is used to form the hard film on the substrate maintained at a temperature of 400 to 550 ° C. in a nitrogen gas atmosphere having a total pressure of 2.7 to 3.3 Pa. To do.

In the method for manufacturing a coated cutting tool of the present invention, it is preferable to apply a bias voltage of −160 to −100 V to the substrate.

In the method for producing a coated cutting tool of the present invention, the composition of the metal element and the semi-metal element of the target is the general formula: Al _α Cr _{1-α-β-γ-δ} B _β Ru _γ , except for unavoidable impurities. C _δ (However, α, 1-α-β-γ-δ, β, γ and δ are atomic ratios of 0.4 ≦ α ≦ 0.75, 0.04 ≦ β ≦ 0.16, 0. It is a number that satisfies 005 ≦ γ ≦ 0.05 and 0 ≦ δ ≦ 0.035).

The coated cutting tool of the present invention has an excellent heat resistance as compared with a conventional cutting tool coated with (AlCrB) N hard film because the hard film has a specific composition and a single structure in which the X-ray diffraction pattern is fcc. It exhibits properties and lubricity, and has a long life. Therefore, it is extremely useful as a cutting tool for inserts, end mills, drills, and the like.

It is a front view which shows an example of the arc ion plating apparatus which can be used for forming a hard film in the coating cutting tool of this invention. 6 is a scanning electron microscope (SEM) photograph (magnification 25,000 times) showing a cross section of the coated cutting tool of Example 1. It is a graph which shows the X-ray photoelectron spectroscopic spectrum which shows the bonding state of B at the center position of the cross section of the hard film of Example 1. FIG. It is a graph which shows the X-ray diffraction pattern of the hard film of Example 1. It is a photograph which shows the crystal structure analyzed from the nanobeam diffraction pattern of the hard film of Example 1. It is a perspective view which shows an example of the insert base material which comprises the coating cutting tool of this invention. It is the schematic which shows an example of the cutting edge exchange type rotary tool which attached the insert.

Embodiments of the present invention will be described in detail below, but the present invention is not limited thereto, and is appropriately modified or improved based on ordinary knowledge of those skilled in the art without departing from the technical idea of the present invention. May be added. Further, the description of one embodiment can be applied as it is to other embodiments unless otherwise specified.

[1] coated cutting tool of the coated cutting tool this embodiment, on the substrate, with the exception of unavoidable impurities, the general _{formula: (Al x Cr 1-x} -y-z B y Ru z) N 1-p _-q O _p C _q (however, x, 1-x-y -z, y, z, 1-p-q, p and q are each an atomic ratio, 0.35 ≦ x ≦ 0.75,0. A hard film having a composition represented by (01 ≦ y ≦ 0.1, 0.005 ≦ z ≦ 0.05, 0.002 ≦ p ≦ 0.010, and 0 ≦ p ≦ 0.03). Have. The X-ray diffraction pattern of the hard film has a single structure of fcc. In the hard film, the peak intensity ratio (BN) / (BO) of the BN bond and the BO bond specified by the X-ray photoelectron spectroscopy is 0.4 to 1.0. Is preferable. The hard film of the present embodiment can be formed by an arc ion plating (AI) method.

(A) Base material The base material needs to be a material that is highly heat resistant and to which a physical vapor deposition method can be applied. Examples of the material of the base material include cemented carbide, cermet, high-speed steel, tool steel, and ceramics such as cubic boron nitride (cBN). From the viewpoint of strength, hardness, abrasion resistance, toughness, thermal stability and the like, a cemented carbide base material or a ceramic base material is preferable. The cemented carbide is composed of tungsten carbide particles and a bonded phase of an alloy mainly composed of Co or Co. The content of the bound phase is preferably 1 to 13.5% by mass, more preferably 3 to 13% by mass. If the content of the bonded phase is less than 1% by mass, the toughness is insufficient, and if the content of the bonded phase exceeds 13.5% by mass, the hardness (wear resistance) is insufficient. The hard film of the present embodiment can be formed on any of the unprocessed surface, the polished surface, and the edge-treated surface of the base material after sintering.

(B) Modified layer of cemented carbide base material When the base material is a cemented carbide, the surface of the base material is irradiated with ions generated from a TiB alloy target described later (hereinafter, also referred to as ion bombard) to obtain an average thickness. It is preferable to form a modified layer having an fcc structure of 1 to 10 nm. The average thickness of the modified layer is measured by the measuring method described in Japanese Patent No. 5967329. Tungsten carbide, which is the main component of cemented carbide, has an hcp structure, but the modified layer has the same fcc structure as the hard film. The portion of the crystal lattice fringes at the boundary (interface) between the cemented carbide base material and the modified layer is preferably 30% or more, more preferably 50% or more, and particularly preferably 70% or more. The cemented carbide base material and the hard film are firmly adhered to each other through the modified layer.

Since the modified layer has an fcc structure and is formed in a high-density thin layer, it is unlikely to be a starting point of fracture. If the average thickness of the modified layer is less than 1 nm, the effect of improving the adhesion of the hard film to the substrate cannot be sufficiently obtained, and if it exceeds 10 nm, the adhesion deteriorates. The average thickness of the modified layer is more preferably 2 to 9 nm.

(C) Hard film (1) Composition The hard film of the present embodiment formed on the substrate by the AI method contains Al, Cr, B, Ru, N and O as essential elements. The composition of the hard film, with the exception of unavoidable impurities, the general _{formula: (Al x Cr 1-x} -y-z B y Ru z) N 1-p-q O p C q ( however, x, 1- xyz, y, z, 1-p-q, p and q are atomic ratios of 0.35 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1 and 0.005 ≦ z, respectively. It is a number that satisfies ≦ 0.05, 0.002 ≦ p ≦ 0.010, and 0 ≦ q ≦ 0.03).

In the hard film of the present embodiment, the range of the atomic ratio x of Al is 0.35 to 0.75. If x is less than 0.35, the Al content of the hard film is too small, so that the oxidation resistance is impaired and the heat resistance is deteriorated. On the other hand, when x exceeds 0.75, a soft hcp structure is formed in the hard film and the wear resistance is impaired. The lower limit of x is preferably 0.4, and the upper limit of x is preferably 0.74.

In the hard film of the present embodiment, the range of the atomic ratio 1-xyz of Cr is 0.635 to 0.10. If 1-x-y-z is less than 0.10, the Al content of the hard film becomes excessive, so that a soft hcp structure is formed in the hard film and the wear resistance is impaired. On the other hand, if 1-x-yz exceeds 0.635, the Al content of the hard film becomes too small, so that the oxidation resistance is impaired and the heat resistance is deteriorated. The lower limit of 1-x-y-z is preferably 0.17, and the upper limit of 1-x-y-z is preferably 0.58.

In the hard film of the present embodiment, the atomic ratio y of B is in the range of 0.01 to 0.1. If y is less than 0.01, the addition effect cannot be obtained and the lubricity is impaired. On the other hand, when y exceeds 0.1, it becomes embrittlement and cannot retain the single structure of fcc. The lower limit of y is preferably 0.02, and the upper limit of y is preferably 0.09.

In the hard film of the present embodiment, the range of the atomic ratio z of Ru is 0.005 to 0.05. If z is less than 0.005, the addition effect cannot be obtained and the heat resistance is impaired. On the other hand, when y exceeds 0.05, the hard film becomes embrittlement. The lower limit of y is preferably 0.01, and the upper limit of y is preferably 0.04.

The range of a is 0.4 to 0, where 1 is the sum of the total atomic ratios a of the metal components Al, Cr and Ru and the metalloid component B and the total b of the atomic ratios of nitrogen, oxygen and carbon. 6 (the range of b is 0.6 to 0.4). That is, the composition of the hard film of the present embodiment, with the exception of unavoidable impurities, the general _{formula: (Al x Cr 1-x} -y-z B y Ru z) a (N 1-p-q O p C q ) _B [However, x, 1-x-y-z, y, z, 1-p-q, p, q, a and b are atomic ratios of 0.35 ≦ x ≦ 0.75, 0. 01 ≦ y ≦ 0.1, 0.005 ≦ z ≦ 0.05, 0.002 ≦ p ≦ 0.010, 0 ≦ q ≦ 0.03, 0.4 ≦ a ≦ 0.6 and a + b = 1. It is a number to satisfy. ] Is represented.
If a is less than 0.4, impurities are likely to be incorporated into the grain boundaries of the hard film of the present embodiment. Impurities are derived from the internal residue of the film forming apparatus. In such a case, the strength of the hard film of the present embodiment is lowered, and the film is easily broken by an external impact. On the other hand, when a exceeds 0.6, the ratio of the metal component AlCrRu and the semimetal component B becomes excessive, the crystal strain of the hard film of the present embodiment becomes large, and the adhesion to the base material decreases. The hard film is easily peeled off. The lower limit of a is preferably 0.40, and the upper limit of a is preferably 0.60.

The range of the atomic ratio 1-p-q of nitrogen (N), which is a non-metal component contained in the hard film of the present embodiment, is 0.998 to 0.960. If 1-p-q is less than 0.960, the wear resistance is lowered, and if it exceeds 0.998, the contents of O and C are too small and the lubricity is lowered. The lower limit of 1-p-q is preferably 0.961, more preferably 0.962. The upper limit of 1-p-q is preferably 0.997, more preferably 0.996. The N content can be analyzed in combination with EPMA and TEM-EDS described later.

The range of the atomic ratio p of oxygen (O), which is a non-metallic component contained in the hard film of the present embodiment, is 0.002 to 0.010. When p is less than 0.002, the oxygen content is too low and the lubricity is lowered, and when p is more than 0.010, the oxygen content is too high and the wear resistance is lowered. The lower limit of p is preferably 0.003, more preferably 0.004. The upper limit of p is preferably 0.009, more preferably 0.008. The O content can be analyzed in combination with EPMA and TEM-EDS described later.

The range of the atomic ratio q of the non-metallic component carbon (C) contained in the hard film of the present embodiment is 0.03 or less. If q is more than 0.03, the wear resistance is lowered. In order to improve the wear resistance, q is preferably 0.01 to 0.03. The C content can be analyzed by EPMA described later.

(2) Film thickness The thickness of the hard film of the present embodiment is preferably 0.5 to 8 μm, more preferably 1 to 5 μm. With a film thickness in this range, peeling of the hard film of the present embodiment from the base material is suppressed, and excellent heat resistance, lubricity, and abrasion resistance are exhibited. If the thickness is less than 0.5 μm, the coating effect of the hard film cannot be sufficiently obtained, and if the thickness exceeds 8 μm, the residual stress becomes excessive and the hard film is easily peeled from the substrate. Here, the "thickness" of the non-flat hard film means the "arithmetic mean thickness".

(3) Crystal structure The X-ray diffraction pattern of the hard film of the present embodiment has a single structure of fcc. In X-ray diffraction, even if a minute phase other than fcc is present, it does not appear in the X-ray diffraction pattern. According to electron diffraction by a transmission electron microscope (TEM) capable of detecting the minute phase of the hard film, the hard film has fcc as a main structure and another structure (hcp or the like) as a substructure. You may. From the viewpoint of practicality, the electron diffraction pattern preferably has fcc as a main structure and hcp as a substructure, and more preferably has a single structure of fcc.

(4) Peak intensity ratio (BN) / (BO)
In the hard film of the present embodiment, the peak intensity ratio (BN) / (BO) of the BN bond and the BO bond identified by X-ray photoelectron spectroscopy is 0.4 to 1. It is preferably 0, and more preferably 0.5 to 0.9. When the peak intensity ratio (BN) / (BO) satisfies the above range, a long-life hard film having both wear resistance and lubricity can be obtained. If the peak intensity ratio is less than 0.4, the BN bond is relatively lowered, so that the wear resistance is lowered. On the other hand, when the peak intensity ratio exceeds 1.0, the BO bond is relatively lowered, so that the lubricity is lowered.

(5) Mechanism The coated cutting tool of the present embodiment has significantly better heat resistance and lubricity than the conventional cutting tool coated with (AlCrB) N hard film, and the mechanism for extending the life is not sufficiently clear. However, it can be considered as follows.
As illustrated in Conventional Example 1 described later, the conventional (AlCrB) N-coated cutting tool has not been able to sufficiently meet the recent demands for long life and high performance. As a result of diligent studies on extending the life and improving the performance of the (AlCrB) N hard film, the present inventor
(A) An AlCrBRu sintered alloy or an AlCrBRuC sintered alloy having an oxygen content of 2000 to 4000 μg / g is used as the target for the hard film of the present embodiment, and (b) the entire nitrogen gas atmosphere at the time of film formation. By setting the pressure to 2.7 to 3.3 Pa,
(C) It was discovered that the film-formed hard film of the present embodiment has a single structure of fcc, and the O content (atomic ratio) can be adjusted to 0.002 to 0.010.
(D) Further, in the hard film, the BN bond and the BO bond coexist in the bond state specified by the X-ray photoelectron spectroscopy, and the peak intensity ratio between the BN bond and the BO bond. It was discovered that (BN) / (BO) can be adjusted to 0.4 to 1.0.
(E) It was found that the coated cutting tool formed by forming the hard film of the present embodiment on the base material exhibited remarkably excellent heat resistance and lubricity, and had a long life and high performance.

That is, it was found that the heat resistance of the hard film of the present embodiment is improved mainly by containing a specific amount of Ru and O. Further, it was found that the BO-bonded portion mainly shared excellent lubricity, and the BN-bonded portion mainly shared excellent wear resistance.

[2] Film forming apparatus An AI apparatus can be used for forming the hard film of the present embodiment. If necessary, when forming a laminated hard film including the hard film of the present embodiment, another physical vapor deposition device (sputtering device or the like) can be used in addition to the AI device. As shown in FIG. 1, for example, the AI device is attached to the decompression container 5, the arc discharge type evaporation sources 13 and 27 attached to the decompression container 5 via the insulator 14, and the arc discharge type evaporation sources 13 and 27, respectively. The attached targets 10 and 18, the arc discharge power supplies 11 and 12 connected to the arc discharge type evaporation sources 13 and 27, and the rotatable column 6 penetrating to the inside of the decompression vessel 5 via the bearing portion 4. A holder 8 supported by a support column 6 for holding the base material 7, a drive unit 1 for rotating the support column 6, and a bias power supply 3 for applying a bias voltage to the base material 7 are provided. The decompression container 5 is provided with a gas introduction unit 2 and an exhaust port 17. The arc ignition mechanisms 16 and 16 are attached to the pressure reducing container 5 via the arc ignition mechanism bearing portions 15 and 15. A filament type electrode 20 is attached to the decompression vessel 5 via insulators 19 and 19 for ionization of the gas (argon gas, nitrogen gas, etc.) introduced into the decompression vessel 5. A shielding plate 23 is provided in the decompression container 5 via a shielding plate bearing portion 21 between the target 10 and the base material 7. The shielding plate 23 is moved, for example, in the vertical or horizontal direction by the shielding plate driving unit 22, and after the shielding plate 23 is made absent between the target 10 and the base material 7, the hard film of the present embodiment is formed. Will be done.

(A) Target of hard film of the present embodiment (1) Composition of sintered alloy As the target for forming the hard film of the present embodiment, for example, Al powder and CrBRu alloy powder or CrBRuC alloy powder having a predetermined composition are used. It is obtained by blending and mixing so as to have the composition of the following AlCrBRu sintered body alloy or AlCrBRuC sintered body alloy, molding the obtained mixed powder, and sintering the obtained molded body. The oxygen content of the target can be adjusted by appropriately selecting the particle size of, for example, Al powder and CrBRu alloy powder or CrBRuC alloy powder.

The composition of the AlCrBRu sintered alloy or the AlCrBRuC sintered alloy, except for unavoidable impurities, is the general formula: Al _α Cr _{1-α-β-γ-δ} B _β Ru _γ C _δ (where α, 1- α-β-γ-δ, β, γ and δ are atomic ratios of 0.4 ≦ α ≦ 0.75, 0.04 ≦ β ≦ 0.16, 0.005 ≦ γ ≦ 0.05 and 0, respectively. It is preferable to have a composition represented by (a number satisfying ≦ δ ≦ 0.035). By setting α, β, γ and δ within the above specific ranges, a target suitable for forming the hard film of the present embodiment can be produced.

In the above sintered alloy, the range of the atomic ratio α of Al is preferably 0.4 to 0.75. If α is less than 0.4, the Al content of the hard film of the present embodiment is too small, so that the oxidation resistance is impaired. On the other hand, when α exceeds 0.75, a soft hcp structure is formed in the hard film and wear resistance is impaired. The lower limit of α is more preferably 0.45, and the upper limit of α is even more preferably 0.72.

The range of the atomic ratio 1-α-β-γ-δ of Cr in the sintered alloy is preferably 0.555 to 0.005. If 1-α-β-γ-δ is less than 0.005, the effect of adding Cr cannot be obtained. On the other hand, if 1-α-β-γ-δ exceeds 0.555, the Al content becomes too small and the oxidation resistance is impaired. The lower limit of 1-α-β-γ-δ is more preferably 0.10, and the upper limit of 1-α-β-γ-δ is even more preferably 0.50.

The range of the atomic ratio β of B of the sintered alloy is preferably 0.04 to 0.16. If β is less than 0.04, the effect of adding B cannot be obtained. On the other hand, if β exceeds 0.16, the hard film does not have a single fcc structure. The lower limit of β is more preferably 0.05, and the upper limit of β is even more preferably 0.15.

(2) Oxygen content of the sintered alloy The oxygen content of the sintered alloy is 2000 to 4000 μg / g. When the oxygen content is less than 2000 μg / g and more than 4000 μg / g, the oxygen content (p) of the hard film of the present embodiment is less than 0.002 and more than 0.010. Further, it does not satisfy the specific range of the peak intensity ratio (BN) / (BO) specified by the X-ray photoelectron spectroscopy. The lower limit of the oxygen content of the sintered alloy is preferably 2050 μg / g, and more preferably 2100 μg / g. On the other hand, the upper limit of the oxygen content of the sintered alloy is preferably 3900 μg / g, and more preferably 3800 μg / g.

(B) TiB alloy target for forming a modified layer The TiB alloy target for forming a modified layer has a general formula: Ti _f B _1-f (where f is an atomic ratio of Ti, except for unavoidable impurities. It is preferable to have a composition represented by (satisfying 0.5 ≦ f ≦ 0.9). If f is less than 0.5, a modified layer having an fcc structure cannot be obtained, and if f is more than 0.9, a decarburized layer is formed and a modified layer having an fcc structure cannot be obtained. The lower limit of f is more preferably 0.7, and the upper limit of f is even more preferably 0.88.

(C) Arc discharge type evaporation source and arc discharge type power supply As shown in FIG. 1, the arc discharge type evaporation sources 13 and 27 are a TiB alloy target 10 for forming a modified layer and a hard film of the present embodiment, respectively. The target 18 for forming is provided. For example, a direct current arc current is applied to the target 10 and a pulse arc current is applied to the target 18 from the arc discharge power supplies 11 and 12, respectively. Although not shown, the vicinity of the base material 7 for forming the hard film of the present embodiment is provided with magnetic field generating means (a structure having an electromagnet and / or a permanent magnet and a yoke) in the arc discharge type evaporation sources 13 and 27. It is preferable to form a magnetic field distribution having a void magnetic flux density of several tens of G (for example, 10 to 50 G).

The target for forming the hard film of the present embodiment contains Al in which droplets are likely to occur. Droplets cause disruption of the growth of polycrystalline grains in the hard film and serve as a starting point for fracture. Therefore, by energizing the target (evaporation source) of the sintered alloy with a DC arc current of 150 to 250 A, excessive generation of droplets can be suppressed.

(D) Bias power supply As shown in FIG. 1, a DC voltage or a pulse bias voltage is applied to the base material 7 from the bias power supply 3.

[3] Film formation conditions The hard film of the present embodiment can be formed by the AI method using the target of the sintered alloy. The conditions for forming the hard film of the present embodiment will be described in detail below for each process.

(A) Base material cleaning step After setting the base material 7 on the holder 8 of the AI device shown in FIG. 1, the inside of the decompression container 5 is 1 to 5 × 10 ^-2 Pa (for example, 1.5 × 10 ^-2). While holding in Pa), the base material 7 is heated to a temperature of 250 to 650 ° C. by a heater (not shown). Although shown as a cylinder in FIG. 1, the base material 7 can take various shapes such as a solid type end mill or an insert. Then, argon gas is introduced into the decompression vessel 5 to create an argon gas atmosphere of 0.5 to 10 Pa (for example, 2 Pa). In this state, a DC bias voltage or a pulse bias voltage of −250 to −150 V is applied to the base material 7 by the bias power supply 3, and the surface of the base material 7 is bombarded with argon ions to clean it.

If the substrate temperature is less than 250 ° C., there is no etching effect due to argon ions, and if the substrate temperature exceeds 650 ° C., it becomes difficult to adjust the substrate temperature. The base material temperature is measured by a thermocouple embedded in the base material (the same applies to the subsequent steps). If the pressure of the argon gas in the decompression vessel 5 is out of the range of 0.5 to 10 Pa, the bombard treatment with argon ions becomes unstable. If the DC bias voltage or pulse bias voltage is less than -250V, arcing occurs on the base material, and if it exceeds -150V, the cleaning effect by etching the bombard cannot be sufficiently obtained.

(B) Reforming layer forming step The ion bombard on the WC-based cemented carbide base material 7 using the TiB alloy target for reforming layer forming has an argon gas atmosphere with a flow rate of 30 to 150 sccm after cleaning the base material 7. A modified layer is formed on the surface of the base material 7. An arc current (direct current) of 50 to 100 A is applied from the arc discharge power supply 11 to the surface of the TiB alloy target 10 attached to the arc discharge type evaporation source 13. The base material 7 is heated to a temperature of 450 to 750 ° C., and a DC bias voltage of −1000 to −600 V is applied from the bias power supply 3 to the base material 7. The base material 7 is irradiated with Ti ions and B ions by such an ion bombard.

If the temperature of the base material 7 is outside the range of 450 to 750 ° C., the modified layer having an fcc structure is not formed, or the decarburized layer is formed on the surface of the base material 7, and the performance of the cutting tool is significantly deteriorated. If the flow rate of argon gas in the vacuum vessel 5 is less than 30 sccm, the energy of Ti ions and the like incident on the base material 7 is too strong, a decarburized layer is formed on the surface of the base material 7, and the adhesion of the hard film of the present embodiment is formed. To spoil. On the other hand, when the flow rate of argon gas exceeds 150 sccm, the energy of Ti ions and the like is weakened, and the reformed layer is not formed.

If the arc current is less than 50 A, the arc discharge becomes unstable, and if it exceeds 100 A, a large number of droplets are formed on the surface of the base material 7 and the adhesion is impaired. If the DC bias voltage is less than −1000 V, the energy of Ti ions or the like is too strong and a decarburized layer is formed on the surface of the base material 7, and if it exceeds −600 V, a modified layer is not formed on the surface of the base material.

(C) Formation step of the hard film of the present embodiment The hard film of the present embodiment is formed on the base material 7 or, when the modified layer is formed, on the modified layer. At this time, nitrogen gas is used to apply an arc current from the arc discharge power supply 12 to the surface of the target 18 attached to the arc discharge type evaporation source 27. At the same time, a DC bias voltage or a unipolar pulse bias voltage is applied from the bias power supply 3 to the base material 7 controlled to the following temperature.

(1) Base material temperature The base material temperature at the time of forming the hard film is set to 400 to 550 ° C. If the substrate temperature is less than 400 ° C., the hard film does not crystallize sufficiently, so that it does not have excellent heat resistance, lubricity and abrasion resistance. In addition, the increase in residual stress causes peeling of the film. On the other hand, when the substrate temperature exceeds 550 ° C., the refinement of the crystal grains of the hard film is promoted, and the heat resistance, lubricity or abrasion resistance is impaired. The substrate temperature is preferably 480 to 540 ° C.

(2) Pressure of nitrogen gas Nitrogen gas having a pressure (total pressure) of 2.7 to 3.3 Pa is used as the film forming gas for forming the hard film of the present embodiment. If the pressure of the nitrogen gas is less than 2.7 Pa, the nitriding of the hard film (formation of BN bond) becomes insufficient, the oxygen content of the hard film becomes excessive, and heterogeneous phases such as non-nitrided AlCrB alloy are generated. appear. On the other hand, when the pressure of the nitrogen gas exceeds 3.3 Pa, the oxygen content of the hard film becomes excessive. Further, the peak intensity of the BN bond becomes larger than the peak intensity of the BO bond. The lower limit of the pressure of the nitrogen gas is preferably 2.8 Pa, more preferably 2.9 Pa. The upper limit of the pressure of the nitrogen gas is preferably 3.2 Pa, more preferably 3.1 Pa.

(3) Flow rate of nitrogen gas The flow rate of nitrogen gas is preferably 750 to 900 sccm. When the flow rate of nitrogen gas is less than 750 sccm and more than 900 sccm, it becomes difficult to adjust the pressure (total pressure) of the nitrogen gas to 2.7 to 3.3 Pa. The lower limit of the flow rate of nitrogen gas is more preferably 770 sccm, and the upper limit of the flow rate of nitrogen gas is further preferably 880 sccm.

(4) Bias voltage applied to the base material A DC bias voltage or a unipolar pulse bias voltage is applied to the base material in order to form the hard film of the present embodiment. The DC bias voltage is preferably −160 to −100 V. If the DC bias voltage is less than −160 V, the B content of the hard film of the present embodiment will be significantly reduced. On the other hand, when the DC bias voltage exceeds -100V, the hard film has a short life. A more preferred range of DC bias voltage is -150 to -110V.

In the case of the unipolar pulse bias voltage, the negative bias voltage (negative peak value excluding the steep rising portion from zero to the negative side) is preferably −160 to −100 V. By setting the negative bias voltage in this range, the hard film of the present embodiment has a long life. A more preferred range of negative bias voltage is -150 to -110V. The frequency of the unipolar pulse bias voltage is preferably 20 to 50 kHz, more preferably 30 to 40 kHz.

(5) Arc current In order to suppress droplets when forming the hard film of the present embodiment, an arc current (direct current) is applied to the hard film forming target (the sintered alloy target) 18. preferable. The arc current is preferably 150 to 250 A. If the arc current is less than 150 A, the arc discharge becomes unstable and it becomes difficult to form the hard film. On the other hand, when the arc current exceeds 250 A, the droplets increase remarkably and the wear resistance deteriorates. It is more preferable that the arc current is 160 to 240 A.

The present invention will be described in more detail with reference to the following examples, but the present invention is of course not limited thereto. In the following examples and comparative examples, the composition of the target metal element and the metalloid element is a measured value by the fluorescent X-ray method unless otherwise specified, and the oxygen content is measured by the carrier gas hot extraction method. It is a measured value. Further, in the examples, the insert is used as the base material of the hard film of the present embodiment, but of course, the present invention is not limited to them, and can be applied to cutting tools (end mills, drills, etc.) other than the insert. is there.

Example 1
(1) Cleaning of base material Finishing milling insert base material made of WC-based cemented carbide containing 8.0% by mass of Co and having a composition of WC and unavoidable impurities in the balance (Mitsubishi Hitachi Tool shown in FIG. 6) ZDFG300-SC manufactured by Mitsubishi Hitachi Tool Co., Ltd.) and insert base material for measuring physical properties (SNMN120408 manufactured by Mitsubishi Hitachi Tool Co., Ltd.) are set on the holder 8 of the AI device shown in FIG. (Not shown) was heated to 550 ° C. After that, argon gas is introduced at a flow rate of 500 sccm (1 atm and cc / min at 25 ° C.) to adjust the pressure in the decompression vessel 5 to 2.0 Pa, and each of the base materials (hereinafter, also referred to as base material 7). ) Was applied with a DC bias voltage of −200 V, and the base material 7 was cleaned by etching argon ions with a bombard.

(2) Formation of Modified Layer Using TiB Alloy Target Argon using a target 10 having a composition represented by Ti _0.8 B _0.2 (atomic ratio) while maintaining the substrate temperature at 550 ° C. The gas flow rate was 70 sccm. A DC voltage of −800 V is applied to the base material 7 by the bias power supply 3, and a DC arc current of 75 A from the arc discharge power supply 11 is passed through the surface of the target 10, and the surface of the base material 7 is modified to have an average thickness of 4 nm. A layer was formed.

(3) Formation of hard film of the present embodiment Al _0.65 Cr _0.22 B _0.10 Ru _0.03 (atomic ratio) of metal element and semi-metal element composition, and oxygen content of 2200 μg / g Using the target 18 made of AlCrBRu sintered alloy, the temperature of the base material 7 was set to 450 ° C., the total pressure of the nitrogen gas in the decompression vessel 5 having a nitrogen gas atmosphere was set to 3.0 Pa, and the nitrogen gas was used. The flow rate of the above was adjusted to 800 sccm.

A DC voltage of −120 V was applied to the base material 7 by the bias power supply 3, and a DC arc current of 200 A was passed from the arc discharge power supply 12 to the target 18, and (Al _0.62 Cr _0. A coated cutting tool (milling insert) having a composition of ₃₂ B _0.03 Ru _0.03 ) N _0.996 O _0.004 (atomic ratio) and forming a hard film having a thickness of 3 μm was produced. The film composition is such that the center position of the hard film in the thickness direction is measured by an electron probe microanalyzer (EPMA, JXA-8500F manufactured by JEOL Ltd.) with an acceleration voltage of 10 kV, an irradiation current of 0.05 A, and a beam diameter of 0.5 μm. It was measured under the conditions of. The measurement conditions of EPMA are the same in other examples. Further, the analysis values of N and O contained in the hard film are the energy dispersive X-ray spectroscope (EDS, NORAN) mounted on the transmission electron microscope (JEM-2100 manufactured by JEOL Ltd.) together with the EPMA analysis value. It was determined in consideration of the TEM-EDS analysis value using a UTW type Si (Li) semiconductor detector, beam diameter: about 1 μm).

FIG. 2 is a scanning electron microscope (SEM) photograph (magnification: 25,000 times) showing the cross-sectional structure of the milling insert. In FIG. 2, 31 indicates a WC-based cemented carbide base material, and 32 indicates a (AlCrBRu) NO hard film having a columnar crystal structure. Since FIG. 2 has a low magnification, the modified layer cannot be seen.

(4) Bonding state of B of (AlCrBRu) NO hard film Using an X-ray photoelectron spectrometer (PHI-5000 VersaprobeII manufactured by PHI), the (AlCrBRu) NO hard film having the above cross-sectional structure is formed in the thickness direction from the surface by argon ions. After etching to a depth of 1/2 (surface side), AlK _α rays (1486.7 eV, 25 kV, monochrome) are irradiated in a range of 100 μm in diameter, and X-ray photoelectron spectroscopy of FIG. 3 showing the bonding state of B is shown. A spectrum was obtained. In FIG. 3, the horizontal axis is the binding energy (eV) and the vertical axis is c / s (counts per second). FIG. 3 shows the detected B1s spectrum and the BO bond and the BN bond obtained by performing peak separation from the B1s spectrum. From FIG. 3, a peak of BN bond was observed at 191 eV and a peak of BO bond was observed at 193 eV, and the peak intensity ratio (BN) / (of these BN bond and BO bond was observed. BO) was 0.7.

(5) X-ray diffraction pattern of (AlCrBRu) NO hard film An X-ray diffractometer (EMPYREAN manufactured by PANalytical) is used to observe the crystal structure of the (AlCrBRu) NO hard film on the insert substrate for measuring physical properties. Then, the surface of the hard film was irradiated with CuKα1 line (wavelength λ: 0.15405 nm) under the following conditions to obtain an X-ray diffraction pattern (FIG. 4).
Tube voltage: 45kV
Tube current: 40mA
Incident angle ω: fixed at 3 ° 2θ: 20-90 °

In FIG. 4, the (111) plane, the (200) plane, the (220) plane, the (311) plane, and the (222) plane are all X-ray diffraction peaks having an fcc structure. Therefore, it can be seen that the (AlCrBRu) NO hard film of this example has a single structure of fcc. In FIG. 4, the X-ray diffraction peak not indexed is the X-ray diffraction peak of the WC-based cemented carbide substrate.

(6) Microstructure of (AlCrBRu) NO hard film 200 kV by transmission electron microscope (JEM-2100) at the center position in the thickness direction of the cross section of the (AlCrB) NO hard film formed on the insert substrate for measuring physical properties. Nanobeam diffraction was performed under the conditions of the accelerating voltage and the camera length of 50 cm. The obtained diffraction image is shown in FIG. In FIG. 5, since the diffraction patterns of the → 1 (111) plane, the → 2 (200) plane, and the → 3 (220) plane of the fcc structure were observed, the (AlCrBRu) NO of the present embodiment was observed. It was found that the hard film had a single structure with an electron diffraction pattern of fcc.

(7) Measurement of tool life As shown in FIGS. 6 and 7, the milling insert (hereinafter, also referred to as an insert) 30 is a tool body 36 of a rotary tool with a replaceable cutting edge (ABPF30S32L150 manufactured by Mitsubishi Hitachi Tool Co., Ltd.) 40. It was attached to the tip 38 using a set screw 37. The blade diameter of the blade tip exchange type rotary tool 40 was set to 30 mm. Cutting is performed under the following milling conditions using a rotary tool 40 with a replaceable cutting edge, and the flank surface of the insert 30 sampled every unit time is observed with an optical microscope (magnification: 100 times), and the wear width of the flank surface is observed. Alternatively, the machining time when the chipping width becomes 0.2 mm or more is determined as the tool life.

Cutting conditions Processing method: Continuous rolling processing Work material: 120 mm x 250 mm S50C square lumber (HB220)
Insert used: ZDFG300-SC (for milling)
Cutting tool: ABPF30S32L150
Cutting speed: 380 m / min Feed amount per blade: 0.3 mm / blade Axial depth of cut: 0.3 mm
Radial depth of cut: 0.1 mm
Cutting fluid: None (dry processing)

In this example, the composition of the sintered alloy target used is shown in Table 1, the formation conditions of the hard film are shown in Table 2, the composition of the hard film is shown in Table 3, and the X-ray diffraction and X-ray diffraction of the hard film and Table 4 shows the measurement results of the crystal structure by electron diffraction, the peak intensity ratio (BN) / (BO), and the tool life.

Examples 2-9
Milling inserts were prepared in the same manner as in Example 1 except that the sintered alloy targets of each example shown in Table 1 were used and the conditions for forming a hard film of each example shown in Table 2 were used. In Examples 2 and 3, the Al and Cr contents of the sintered alloy target were changed as compared with Example 1. In Examples 4 and 5, the B content was changed with respect to Example 1. In Examples 6 and 9, the total pressure of nitrogen gas was changed as compared with Example 1. In Example 7, the bias voltage was changed with respect to Example 5. In Example 8, the oxygen content of the sintered alloy target was changed as compared with Example 1. The composition of the sintered alloy target of each example is shown in Table 1, the formation conditions of the hard film of each example are shown in Table 2, the composition of the hard film of each example is shown in Table 3, and each of the above. Table 4 shows the measurement results of the crystal structure by X-ray diffraction and electron diffraction of the hard film of the example, the peak intensity ratio (BN) / (BO), and the tool life of each of the above examples.

Comparative Example 1
A milling insert was produced in the same manner as in Example 1 except that the total pressure of the nitrogen gas atmosphere in the decompression vessel 5 at the time of forming the hard film was adjusted to 2 Pa and the flow rate of the nitrogen gas was adjusted to 700 sccm.

Comparative Example 2
A milling insert was produced in the same manner as in Example 1 except that the total pressure of the nitrogen gas atmosphere in the decompression vessel 5 at the time of forming the hard film was adjusted to 3.5 Pa and the flow rate of the nitrogen gas was adjusted to 900 sccm.

Comparative Example 3
A milling insert was produced in the same manner as in Example 1 except that a sintered alloy target (Table 1) having an excessively low oxygen content (470 μg / g) was used.

Comparative Example 4
A milling insert was produced in the same manner as in Example 1 except that a sintered alloy target (Table 1) having an excessive oxygen content (5450 μg / g) was used.

Conventional example 1
<Trace experiment of film formation conditions of the second layer of sample No. 4 in Table 1 of Patent Document 3 (Japanese Unexamined Patent Publication No. 2005-330039)>
Nitrogen gas flow rate during film formation of (AlCrB) N hard film using AlCrB alloy target (Table 1): 200 sccm, total nitrogen gas pressure: 1 Pa, arc current: 200 A, and substrate bias voltage: -50 V ( A milling insert coated with a (AlCrB) N hard film was produced in the same manner as in Example 1 except for Table 2).

Example 10
A milling insert coated with a (AlCrBRu) NO hard film was produced in the same manner as in Example 1 except that a modified layer using a TiB alloy target was not formed on the surface of the WC-based cemented carbide base material. The composition of the sintered alloy target used is shown in Table 1, the film formation conditions of the hard film used are shown in Table 2, the composition of the obtained hard film is shown in Table 3, and the X-ray diffraction of the hard film is shown. Table 4 shows the measurement results of the crystal structure by electron diffraction, the peak intensity ratio (BN) / (BO), and the tool life.

Examples 11-13
A milling insert coated with the (AlCrBRu) NOC hard film of each example was produced in the same manner as in Example 1 except that the sintered alloy target of each example shown in Table 1 was used. The composition of the sintered alloy target of each example is shown in Table 1, the formation conditions of the hard film of each example are shown in Table 2, the composition of the hard film of each example is shown in Table 3, and each of the above. Table 4 shows the measurement results of the crystal structure by X-ray diffraction and electron diffraction of the example hard film, the peak intensity ratio (BN) / (BO), and the tool life.

From Table 3, the oxygen content (p) of each of the hard films of Examples 1 to 13 was in the range of 0.002 to 0.010. Further, from Table 4, in each of the hard coatings of Examples 1, 2 and 8, the peak intensity ratio (BN / BO) of the BN bond to the BO bond was 0. It was in the range of 4 to 1.0. The p of the hard film of Example 1 was 0.004, and the peak intensity ratio (BN / BO) was 0.7. The life of the replaceable cutting edge rotary tool equipped with the milling insert of Example 1 was 420 minutes, which was a long life. Further, from Tables 3 and 4, the life of each of the blade tip exchange type rotary tools of Examples 11 to 13 in which the (AlCrBRu) NOC film having a predetermined composition was formed was 425 to 430 minutes, which was the longest life. The p of the hard film of Example 11 was 0.003, and the peak intensity ratio (BN / BO) was 0.6. On the other hand, the life of the cutting edge replaceable rotary tool equipped with the milling insert of Example 10 in which the modified layer by the TiB alloy target was not formed was 320 minutes, and Examples 1 to 9 in which the modified layer was formed were formed. It had a shorter life than each of the 11 to 13 cutting edge replaceable rotary tools. However, the life of the replaceable cutting edge rotary tool of Example 10 was longer than that of each of the comparative examples and the replaceable cutting edge rotary tool of Conventional Example 1.

As described above, from Tables 3 and 4, each of the blade tip exchange type rotary tools of Comparative Examples 1 to 4 and Conventional Example 1 had a short life. From Tables 3 and 4, the main reason for this is that the hard film of Comparative Example 1 had a p of 0.012 and a peak intensity ratio (BN / BO) of 0.3, which is good. It is judged that this is because the heat resistance, lubricity and abrasion resistance were not obtained. In the hard film of Comparative Example 2, p was 0.001 and the peak intensity ratio (BN / BO) was 2.1, so that good heat resistance, lubricity and abrasion resistance were obtained. It is judged that this was because it was not done. It is judged that good heat resistance, lubricity and abrasion resistance could not be obtained in the hard films of Comparative Examples 3 and 4 because p was 0.001 and 0.016, respectively, which were outside the present invention. .. In the (AlCrB) N hard film of Conventional Example 1, p was 0.013 because the flow rate and pressure of nitrogen gas were low. Moreover, since the (AlCrB) N hard film of Conventional Example 1 has a composition in which Ru is not added, it is judged that good heat resistance, lubricity and abrasion resistance cannot be obtained.

1: Drive part 2: Gas introduction part 3: Bias power supply 4: Bearing part 5: Decompression container 6: Lower holder (support)
7: Base material 8: Upper holder 10, 18: Cathodic substance (target)
11, 12: Power supply for arc discharge 13, 27: Arc discharge type evaporation source 14: Insulator for fixing arc discharge type evaporation source 15: Arc ignition mechanism bearing 16: Arc ignition mechanism 17: Exhaust port 19: Insulation for fixing electrodes Object 20: Electrode 21: Shielding plate bearing part 22: Shielding plate driving part 23: Shielding plate 30: Insert for milling (insert base material)
31: WC-based cemented carbide base material 32: Hard film 35: Insert rake face 36: Tool body 37: Insert set screw 38: Tool body tip 40: Cutting edge replaceable rotary tool

Claims (5)

A coating cutting tool in which a hard film is formed on a base material.
The hard coating _{(Al x Cr 1-x-} y-z B y Ru z) N 1-p-q O p C q ( however, x, 1-x-y -z, y, z, 1-p −Q, p and q are atomic ratios of 0.35 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.005 ≦ z ≦ 0.05, 0.002 ≦ p ≦ 0. A coating cutting tool having a composition represented by 010 and 0 ≦ q ≦ 0.03) and an X-ray diffraction pattern having a single structure of fcc. In the coating cutting tool according to claim 1, the peak intensity ratio (BN) / (BO) of the BN bond and the BO bond specified by the X-ray photoelectron spectroscopy of the hard film. A coated cutting tool, characterized in that the value is 0.4 to 1.0. A method of manufacturing the coated cutting tool according to claim 1 or 2 by the arc ion plating method.
An AlCrBRu sintered alloy or an AlCrBRuC sintered alloy having an oxygen content of 2000 to 4000 μg / g is used as an arc discharge type evaporation source (target) in a nitrogen gas atmosphere having a total pressure of 2.7 to 3.3 Pa. A method for manufacturing a coated cutting tool, which comprises forming the hard film on the base material maintained at a temperature of 400 to 550 ° C. The method for manufacturing a coated cutting tool according to claim 3, wherein a bias voltage of −160 to −100 V is applied to the base material. In the method for manufacturing a coated cutting tool according to claim 3 or 4, the composition of the target metal element and semi-metal element is Al _α Cr _{1-α-β-γ-δ} B _β Ru _γ C _δ (however, α). , 1-α-β-γ-δ, β, γ and δ are atomic ratios of 0.4 ≦ α ≦ 0.75, 0.04 ≦ β ≦ 0.16, 0.005 ≦ γ ≦ 0. A method for manufacturing a coated cutting tool, which is represented by 05 and 0 ≦ δ ≦ 0.035.).