JP2011093085A - Hard film-coated tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool coated with a hard film, having an excellent wear resistance, while reducing a compressive stress and ensuring an adhesiveness in a hard film of two or more thick layers. <P>SOLUTION: In the tool with a hard film, in which a base body of cemented carbide is coated with the hard film having a compressive stress in a film thickness of 3-20 μm, a first hard film and a second hard film are coated thereon. The first hard film is (Al<SB>a</SB>Cr<SB>1-a-b</SB>Si<SB>b</SB>)<SB>c</SB>N<SB>d</SB>, wherein a and b are atom%, c and d are atomic ratios, and 50≤a≤70; 0≤b≤15; and 0.85≤c/d≤1.25. The second hard film is (Ti<SB>1-e</SB>Si<SB>e</SB>)<SB>f</SB>N<SB>g</SB>, wherein e is atom%, f and g are atomic ratios, and 1≤e≤20; and 0.85≤f/g≤1.25. The following expression: 0.965≤d1/d2≤0.990 is satisfied, wherein d1 and d2 are the interlayer spacings (nm) of (200) planes in the X-ray diffraction of the first hard film and second hard film, respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a cutting tool used for metal part processing or the like, and uses a physical vapor deposition method (hereinafter referred to as a PVD method) on a tool surface that requires improved wear resistance and fracture resistance. The present invention relates to a hard film coated tool coated with

  Patent Documents 1 and 2 disclose the orientation of the (200) plane and the half-value width of the diffraction peak in X-ray diffraction of a hard film coated by the PVD method. Patent Document 3 discloses a technique for controlling peak intensity on the (220) plane and the (111) plane. Patent Document 4 discloses a technique for adjusting the constituent ratio of a metal element and a gas component element constituting a hard coating. Patent Document 5 discloses a technique for improving the adhesion at the film interface by epitaxial growth. Patent Documents 6 and 7 disclose a technique related to an (AlCr) N-based film, and Patent Document 8 discloses a technique related to an (AlCrSi) N-based film. Patent Document 9 discloses a technique of using a lower layer (TiAl) N coating for improving the adhesion of a (TiSi) N-based coating. Patent Document 10 discloses a technique of laminating in order to improve the wear resistance of a hard film containing Si. Patent Document 11 discloses a technique related to thickening a film by the PVD method. Patent Document 12 discloses a technique for improving oxidation resistance by laminating a (TiSi) (BN) hard coating and an (AlCr) N hard coating. Patent Document 13 discloses a technique for forming an (AlCr) N film as a hard film having better wear resistance than an (Al, Ti) (N, C) -based film. However, Patent Documents 12 and 13 do not describe the orientation in X-ray diffraction.

JP 2003-136302 A JP 2003-145313 A JP 2003-71611 A JP-A-7-188901 JP 2001-181826 A JP-A-6-322517 Japanese Patent Laid-Open No. 10-25566 Japanese Patent Laying-Open No. 2005-126736 JP 2000-218407 A JP 2006-137882 A JP 2008-75178 A JP 2002-331408 A JP 2006-144128 A

  However, in the hard coatings described in Patent Documents 1 to 8, the height of the tool under the recent severe cutting conditions of further improving the wear resistance while ensuring the reduction of the compressive stress and the adhesion in the thick hard coating. It cannot meet the demand for performance. Further, the (TiAl) N coating described in Patent Document 9 has a problem that the high-temperature strength is insufficient in a high-speed cutting environment. In the laminated hard film described in Patent Document 10, the thickness of each layer is very thin as 0.5 nm or more and less than 20 nm, and the stress of the laminated part becomes excessive, so the film thickness of the entire film should be increased. I can't. The film thickening technique by the PVD method described in Patent Document 11 is limited to the disclosure of only a thick film thickening technique in a single layer of a hard film, and there is no description of a thick film having two or more layers. In the laminated hard film described in Patent Document 12, adhesion strength and oxidation resistance are improved by a combination of a (TiSi) (NB) hard film and an AlCrN hard film that impart welding resistance. However, all are disclosed only for a film thickness of about 3 μm, and no study has been made on reducing the residual compressive stress when the hard film is thickened. In the hard coating described in Patent Document 13, the composite nitride of (Al1-yCry) having a film thickness of 0.1 to 20 μm has a high temperature oxidation resistance and a coating within a range of 0 <y ≦ 0.3. Although the hardness has been improved, no study has been made on reducing the residual compressive stress when the hard coating is thickened. Therefore, the problem to be solved by the present invention is to provide a hard film-coated tool that is superior in wear resistance as compared with the prior art while ensuring reduction in compressive stress and adhesion in a hard film having two or more layers that are thickened. Is to provide.

The hard film coated tool of the present invention is a hard film coated tool in which a hard film having a compressive stress is coated on a substrate with a cemented carbide in a film thickness of 3 to 20 μm. The first hard coating and the second hard coating are alternately coated with at least one layer, and have at least one first hard coating between the second hard coating and the substrate, The first hard coating is represented by (Al _a Cr _1-ab Si _b ) _c N _d , where a and b are atomic%, c and d represent an atomic ratio, and 50 ≦ a ≦ 70. 0 ≦ b <15 and 0.85 ≦ c / d ≦ 1.25, and the second hard coating is represented by (Ti _1-e Si _e ) _f N _g , where e is atomic% F and g represent an atomic ratio, 1 ≦ e ≦ 20 and 0.85 ≦ f / g ≦ 1.25, and the first hard The crystal structure of the film and the second hard film is a face-centered cubic structure. In the X-ray diffraction of the first hard film, the peak intensity of the (111) plane is Ir, the peak intensity of the (200) plane is Is and When the peak intensity of the (220) plane is It, 0.5 ≦ Is / Ir ≦ 10.0 and 0.6 ≦ It / Ir ≦ 1.5, and the first hard coating and the second When the interplanar spacing (nm) of the (200) plane in the X-ray diffraction of the hard coating is d1 and d2, respectively, 0.965 ≦ d1 / d2 ≦ 0.990, and the second hard coating is a columnar crystal. It has a structure, and the crystal grains of the columnar crystal structure have a composition modulation structure having a composition difference in Si component. By adopting the above-described configuration, it is possible to provide a hard film-coated tool having excellent wear resistance while ensuring a reduction in compressive stress and adhesion in a thick hard film. That is, by setting the d1 / d2 value in the range of 0.965 ≦ d1 / d2 ≦ 0.990, it is excellent even if the first hard coating and the second hard coating are a combination of a Ti-based coating and a Cr-based coating. Adhesion can be secured. For that purpose, it is necessary to set the range of 0.965 ≦ d1 / d2 ≦ 0.990 while securing a residual compressive stress of 2 to 6 GPa in the first hard coating and the second hard coating.

  In order to improve lubricity and wear resistance, the hard film-coated tool of the present invention is a nonmetallic component N element in the first hard film, a part of which is one of C element and O element or Substituting with two kinds of elements, when the whole non-metallic component is 100 atomic%, the content of C element is x and the content of O element is y in atomic%, 0 <x ≦ 10, 0 <y ≦ 10 and 0 <x + y ≦ 10, and the content of N element is preferably 100−xy. In addition, when taking a multilayer structure, when the film thickness of the first hard film is T1 (μm) and the film thickness of the second hard film is T2 (μm), the adhesiveness is increased due to an increase in residual compressive stress of each layer. Since it deteriorates and delamination easily occurs, it is preferable to satisfy 0.1 ≦ T1 <5.0 and 0.1 ≦ T2 <4.0 in order to avoid this. In order to improve the adhesion between the hard coating and the substrate, the Ti layer or one selected from nitrides, carbides and carbonitrides containing Ti as the main component between the cemented carbide substrate and the first hard coating. Or it has an adhesion improvement layer comprised from 2 or more types, and it is preferable that the film thickness of this adhesion improvement layer is 1 micrometer or less.

  An object of the present invention is to provide a hard film-coated tool that is superior in wear resistance as compared with the prior art while ensuring reduction in compressive stress and adhesion in a thick hard film.

  The first hard film in the hard film-coated tool of the present invention is a nitride film containing Al and Cr as main metal components and is excellent in heat resistance. The first hard coating exhibits excellent heat resistance and wear resistance when the a value representing the Al content is in the range of 50 ≦ a ≦ 70 in atomic percent. On the other hand, when the a value exceeds 70 atomic%, a> 0.70, particularly a ≧ 0.75, it is easy to generate AlN having a hexagonal close-packed structure (hereinafter referred to as hcp structure). Not only the adhesion strength deteriorates, but also the hardness decreases. Also, when the Cr content is higher than the Al content, the residual compressive stress increases and the adhesion strength decreases. Further, when a small amount of Si is contained, oxidation resistance and film hardness are improved. The b value representing the Si content is atomic percent and is less than 15%. The reason is that when the content is 15 atomic% or more, the columnar crystal structure is damaged and the compressive stress is remarkably increased, so that the film is liable to self-destruct, and the abrasion resistance is remarkably deteriorated due to peeling and abnormal wear. is there. The case where the Si content is 0 atomic% is also included in the present invention. In the following description, when “%” is simply described, it means atomic%.

  By setting the ratio c / d value between the metal component and the non-metal component of the first hard coating to 0.85 to 1.25, the compressive stress of the hard coating can be adjusted to an optimum range, and high adhesion is achieved. Can be obtained. Moreover, the structure of the hard film can be a columnar crystal structure having high toughness, and excellent chipping resistance and wear resistance can be obtained. When the c / d value is less than 0.85, the crystal lattice strain becomes large, the residual compressive stress is increased, and the adhesiveness is deteriorated. When the c / d value exceeds 1.25, the hard film has a columnar crystal structure, but impurities are easily taken into the grain boundary portion of the crystal, so that the bonding strength between the crystal grains is deteriorated, and the hard film is exposed from the outside. Easily destroyed by impact. By controlling the composition of the hard coating used in the present invention in the range of 0.85 ≦ c / d ≦ 1.25, the residual compressive stress of the coating is in the range of 1.5 to 5.0 GPa. From the viewpoint of industrial productivity, it is possible to determine the c / d value and manage the residual compressive stress of the hard coating.

  When the second hard film is a nitride having a face-centered cubic structure containing Ti and Si, excellent oxidation resistance and wear resistance can be realized. The e value (atomic%) indicating the Si content in the second hard coating is 1 ≦ e ≦ 20. This is important for making the second hard coating a columnar crystal structure. Further, when Si element is contained, not only the oxidation resistance of the film itself is improved, but also a very dense complex oxide containing Si is formed at the initial stage of cutting, and this complex oxide serves as an oxidation protective film. Because of this, it exhibits the effect of suppressing the oxidation inside the hard coating. However, if the e value exceeds 20%, the structure of the film becomes finer and the adhesion strength is significantly reduced. The e value is effective even if it is about 1%, but if it is less than 1%, it becomes difficult to perform quality control because detection with a general-purpose analytical facility becomes difficult. Therefore, it was set to 1% or more that can be detected by the analyzer.

  Further, by controlling the ratio f / g ratio of the metal component and the non-metal component of the second hard coating to 0.85 to 1.25, the compressive stress of the coating can be adjusted to an optimum range, and high adhesion Can be obtained. In addition, when the hard film structure is a columnar crystal structure having high toughness, excellent fracture resistance and wear resistance can be obtained. When both the first hard film and the second hard film have a face-centered cubic structure, a hard film having high hardness can be obtained. Further, by controlling the film structure to a columnar crystal structure, excellent fracture resistance and wear resistance can be obtained.

  In order to control the first hard film in the range of 0.85 ≦ c / d ≦ 1.25, it is important to control the reaction pressure during film formation. In order to obtain nitride, the reaction pressure of nitrogen gas is set to 3 Pa to 8 Pa. More preferably, it is controlled in the range of 3.5 Pa to 7 Pa. When the reaction pressure is less than 3 Pa, the c / d value is 1.25 or more. On the other hand, when the film is formed under a condition exceeding 8 Pa, the c / d value is less than 0.85.

  As a condition for forming the first hard coating, it is necessary to perform control by amplifying the pulsed bias voltage amplitude to be negative and positive. Here, making the bias voltage application negative and positive is called bipolar bias. On the other hand, making the bias voltage amplitude to be a negative value is called unipolar bias. By compressing the first hard film strongly in the (200) plane, the compressive stress of the hard film can be controlled. When the orientation to the (111) plane is increased, the compressive stress is increased and the adhesion of the hard coating is decreased. As a result, the chipping resistance and wear resistance are lowered, resulting in inconvenience. In order to control within the range of excellent wear resistance and appropriate residual compressive stress, the Is / Ir value is set to 0.5 ≦ Is / Ir ≦ 10.0, and the It / Ir value is set to 0.6 ≦ It / It must be controlled within the range of Ir ≦ 1.5. This is because excellent wear resistance can be realized by setting 0.5 ≦ Is / Ir ≦ 10.0. Moreover, it is because it can control to the range of an appropriate residual compressive stress by setting it as 0.6 <= It / Ir <= 1.5. However, when the Is / Ir value exceeds 10.0, the compressive stress is reduced, but the hardness of the hard coating is lowered and the wear resistance is deteriorated. On the other hand, when the Is / Ir value is less than 0.5, the peak of the (111) plane appears greatly and the hardness of the film is improved, but the residual compressive stress becomes too high and the film self-destructs. Moreover, if the It / Ir value is less than 0.6, the internal defects of the hard coating increase, and if the It / Ir value exceeds 1.5, crack fracture in the direction substantially perpendicular from the coating surface to the substrate tends to occur. Become. As a result, the chipping resistance and wear resistance cannot be improved.

  In order to realize these, it is preferable to control the bias voltage as described below as a condition for forming the first hard film. For example, applying the bias voltage in a pulsed manner. When the bias voltage is applied in a pulsed manner, the peak intensity on the (111) plane, the (200) plane, and the (220) plane can be changed. In particular, by suppressing crystal growth on the (111) plane, compressive stress can be suppressed and adhesion can be enhanced. Specifically, it is preferable to control the negative bias voltage value in the range of −20 to −120 (V) and the positive bias voltage in the range of 5 to 10 (V). At this time, the pulse waveform is preferably rectangular. The pulse frequency for pulsing the bias voltage is preferably controlled in the range of 5 to 35 kHz. Further, the ratio of the application time of the positive baice value and the negative bias value at the time of applying the pulse bias is preferably 1: 1, but it may be appropriately adjusted depending on the film forming apparatus and the film composition.

  If the negative bias voltage is larger than −20 (V) on the positive side, the Is / Ir value exceeds 10. When the negative bias voltage is smaller than −120 (V) on the negative side, the Is / Ir value becomes less than 0.5. If the positive bias voltage exceeds 10 (V), the It / Ir value exceeds 1.5. If the positive bias voltage is less than 5 (V), the It / Ir value is less than 0.6.

  It is preferable to control the negative bias voltage to -20 to -80 (V) and the positive bias voltage to 5 to 10 (V) by pulsing the bias voltage applied when forming the second hard film. Thus, the kinetic energy of Si ions reaching the substrate can be kept low. Therefore, it is taken into the crystal lattice of TiN, and the hard film has a columnar crystal structure containing Si. Here, the columnar crystal structure is a structure of a crystal grown in a vertically long shape extending in the film thickness direction. In this case, when the negative bias voltage is larger than 20 (V) on the positive side, the compressive stress is reduced, but the hardness of the hard coating is lowered and the wear resistance tends to be deteriorated. When the negative bias voltage is smaller than −80 (V) on the negative side, the hardness of the film is improved, but the residual compressive stress becomes too high and the film self-destructs.

  In addition, when a film is formed using a target having a different Si content while applying a pulsed bias voltage, the composition of the crystal grains of the columnar crystal structure has a compositional difference in the Si component with respect to the crystal grain growth direction. It preferably has a structure. This is because the mechanical strength of the film is increased by having a compositional modulation structure of the Si component and controlling the residual compressive stress. In this case, the difference in composition of the Si component is preferably 10% at the maximum. More preferably, it is good to control in the range of 0.1% or more and 7% or less.

  For the hard coating used in the present invention, it is important that the d1 / d2 value is 0.965 ≦ d1 / d2 ≦ 0.990. From the present invention, the adhesion between the first hard film and the second hard film is remarkably improved, and the wear resistance is excellent. In the present invention, improvement in adhesion between the films is important for improving wear resistance. In order to improve the adhesion between the films, it is necessary to reduce the crystal lattice strain between the films. In order to reduce this distortion, it is necessary to reduce the misfit by reducing the difference in the (200) plane spacing between the coatings. Thereby, high adhesiveness is obtained. Therefore, the d1 / d2 value is controlled in the range of 0.965 ≦ d1 / d2 ≦ 0.990. As a result, a hard coating excellent in wear resistance and chipping resistance can be obtained without impairing adhesion to the substrate. Specifically, as a condition for forming the first hard film and the second hard film, the pulsed bias voltage is applied with negative and positive amplitudes, and the pulse frequency is set to 5 to 35 kHz. It is preferable to control within the range.

  If the d1 / d2 value is less than 0.965, the consistency in the atomic arrangement at the interface between the first hard film and the second hard film is low, which causes the film to peel at the interface. It is difficult to make the d1 / d2 value larger than 0.990 because of the composition of the first hard film and the second hard film specified in the present invention. By setting the above conditions, it is possible to control the residual compressive stress and the like of the first hard film and the second hard film to an appropriate range, and to form films of different composition systems with good consistency.

  The residual compressive stress of the second hard coating has a correlation with the Iv / Iu value and the Iw / Iu value. Since the second hard film tends to have a high residual compressive stress, deterioration of the adhesion strength with the first hard film must be avoided. Therefore, in order to ensure the adhesion strength of the first and second hard coatings, it is preferable to control the Iv / Iu value and the Iw / Iu value. In addition, it is preferable to maintain the second hard coating at a high hardness while matching the crystal orientation of the second hard coating with the crystal orientation of the first hard coating to ensure adhesion strength. At this time, it is preferable that the strongest peak surface of the second hard coating is the (200) surface as in the first hard coating. Therefore, by setting 1.0 ≦ Iv / Iu ≦ 10.0 and 1.0 ≦ Iw / Iu ≦ 1.5, a high hardness hard coating having high adhesion strength between the first and second hard coatings Can be formed.

  On the other hand, in the case of Iv / Iu <1.0 and Iw / Iu <1.0, the second hard film is strongly oriented in the (111) plane, so that the crystal structure is refined and the second hard film The film has a high hardness, but the residual compressive stress is too high. In addition, when Iv / Iu> 10.0 or Iw / Iu> 1.5, the crystal structure becomes a large columnar shape, and cracks easily propagate along the crystal grain boundary, so that chipping during cutting is performed. It tends to occur. The control of the Iv / Iu value and the Iw / Iu value largely depends on the bias voltage value at the time of film formation and the bias voltage application method. That is, it is possible to control the Iv / Iu value and the Iw / Iu value by applying the bias voltage intermittently (pulsed).

  It is preferable to control the negative bias voltage to -20 to -80 (V) and the positive bias voltage to 5 to 10 (V) by pulsing the bias voltage applied when forming the second hard film. Thus, the kinetic energy of Si ions reaching the substrate can be kept low. Therefore, it is taken into the crystal lattice of TiN, and the hard film has a columnar crystal structure containing Si. Here, the columnar crystal structure is a structure of a crystal grown in a vertically long shape extending in the film thickness direction. In this case, if the negative bias voltage is larger than −20 (V) on the positive side, the (200) plane shows a stronger orientation, and Iv / Iu> 10.0 and Iw / Iu> 1.5, and the residual Although the compressive stress is reduced, the hardness of the second hard coating is lowered, and the wear resistance tends to deteriorate. When the negative bias voltage is smaller than −80 (V) on the negative side, strong orientation is exhibited on the (111) plane, and Iv / Iu <1.0 and Iw / Iu <1.0. Although the hardness of the film is improved, the residual compressive stress becomes too high and self-destruction of the film occurs.

For the N element of the non-metallic component in the first hard coating, a part thereof is replaced with one or two elements of the C element and the O element, and the content of the C element in atomic% is set to the x value and the O element. When the y content is defined as y value, it is preferable that 0 <x ≦ 10, 0 <y ≦ 10, and 0 <x + y ≦ 10. As a result, a hard coating having high hardness, excellent oxidation resistance, adhesion and lubrication can be obtained. When the first hard film contains either or both of the C element and the O element, it is preferable to use a hydrocarbon-based gas or an oxygen-containing gas. When film formation is performed by introducing a gas, the total pressure combined with the N ₂ gas is preferably in the range of 3 to 8 Pa. Alternatively, the target evaporation source can contain an appropriate amount of either or both of the C element and the O element.

  By setting the film thickness of the entire hard coating to 3 μm or more, excellent wear resistance can be obtained. However, when the film thickness exceeds 20 μm, the hard coating film has high compressive stress and deteriorates the adhesion with the substrate. If it is less than 3 μm, the wear resistance is greatly reduced. Moreover, it is preferable that the film thickness of a 1st hard film is thicker than a 2nd hard film, and it is more preferable that the total film thickness of a 2nd hard film is 50% or less with respect to the film thickness of the whole hard film.

  The hard film-coated tool of the present invention has a multilayer structure of a first hard film and a second hard film. Here, the multilayer structure is preferably a film structure having three or more layers. It is preferable that the T1 value (μm) is 0.1 ≦ T1 <5.0 and the T2 value (μm) is 0.1 ≦ T2 <4.0. This is because the wear resistance of the first hard coating is not sufficiently exhibited when T1 <0.1. In the case of T1 ≧ 5.0, the residual compressive stress becomes excessive, the adhesion strength at the interface between the substrate and the hard film and the interface between the first hard film and the second hard film is lowered, and peeling is likely to occur. More preferably, 1 ≦ T1 ≦ 4. In addition, since a 2nd hard film contains Si, it exists in the tendency for a residual compressive stress to become high. In the case of T2 ≧ 4.0, self-destruction of the film occurs at the edge portion of the cutting edge of the tool. Moreover, in order to give desired abrasion resistance to a 2nd hard film, it is preferable that it is 0.1 micrometer or more. More preferably, 0.3 ≦ T1 ≦ 2. Abrasion resistance improves because a 2nd hard film is an uppermost layer.

  In the hard film coated tool of the present invention, a Ti layer or a Ti-based nitride, carbide and carbonitride are selected for the purpose of improving adhesion between the cemented carbide substrate and the first hard film. It is preferable that the adhesion improving layer has one or more adhesion improving layers, and the film thickness of the adhesion improving layer is preferably 1 μm or less.

  The composition of the hard film used in the present invention can be measured using, for example, a JXA8500F type EPMA analyzer manufactured by JEOL Ltd. In the vertical section of the hard coating or the inclined section polished by tilting the film cross section at an angle of 17 degrees, the hard coating is performed from a position not affected by the substrate, the acceleration voltage is 10 (kV), the irradiation current is 1.0 μA, and the probe diameter. Can be set to about 10 μm. When measuring from the surface of the hard coating, the probe diameter is preferably set to about 50 μm. Moreover, when C element and O element are contained, if it is less than 2%, detection by analysis becomes difficult. The film thickness of the hard coating can be measured from a vertical break using, for example, an S-4200 type electrolytic radiation scanning electron microscope manufactured by Hitachi, Ltd.

  The measurement of the peak intensity ratio of the (111), (200) and (220) planes in the X-ray diffraction of the hard coating is performed using, for example, a 2θ-θ scanning method using a RU-200BH type X-ray diffractometer manufactured by Rigaku Corporation. Can be measured. The range of 2θ (degrees) was 10 to 145 degrees, the X-ray source used was a CuKα1 line having a λ value of 0.15405 nm, and background noise was removed by software built in the apparatus. As a result of the measurement, the detected 2θ peak position substantially coincided with the X-ray diffraction pattern (JCPDS file number 38-1420) of TiN whose crystal structure is a face-centered cubic structure. And the intensity of the (220) peak was measured. For the peak intensity, the maximum value of the peak top on each index plane was taken as the peak intensity, and the peak intensity ratio was determined using this. Furthermore, the numerical value of the peak position which shows the said (200) plane was applied to the surface space | interval. Similarly, the peak intensity was measured in the case of a hard film based on CrN.

  The residual compressive stress in the hard coating used in the present invention was calculated by the curvature measurement method shown below. That is, when a test piece obtained by processing a substrate having a known Young's modulus and Poisson's ratio into a predetermined shape and the surface is coated with a hard film, the test is covered by residual compressive stress generated in the hard film. The piece bends and deforms. The amount of deflection deformation was obtained, and the residual compressive stress σ value of the entire hard coating was calculated using the following equation (1).

(Equation 1)
σ = (E · D ² · δ) / (3 · l ² · (1−νs) · d)

  Here, the Es value (GPa) is the Young's modulus of the substrate used for the test piece, the D value (mm) is the thickness of the test piece, the δ value (μm) is the amount of deflection of the test piece before and after coating, and the l value ( mm) is the length from the end surface in the longitudinal direction of the test piece where the deflection is caused by the coating to the maximum deflection, νs value is the Poisson's ratio of the substrate used for the test piece, and d (μm) is the test piece surface. The film thickness of the hard coating. In addition, as a material for forming the test piece, a cemented carbide material is suitable with little variation in measured numerical values. The shape of the test piece is preferably a strip shape, and 8 mm width, 25 mm length, and 0.5 to 1.5 mm thickness were used. With this test piece shape, there is little variation in measured numerical values. The upper and lower surfaces having a large area of the test piece are mirror-polished so that the parallelism is ± 0.1 mm, and then heat-treated in a vacuum of 600 to 1000 ° C. The distortion was removed. If the strain is not removed to some extent as described above, the resulting residual compressive stress value varies. After measuring the deflection deformation amount of one mirror-finished surface having a large test piece area before coating, the surface was coated, and the deflection amount of the obtained coated test piece was measured again. Measure the amount of deflection before and after coating, the length from the end surface in the length direction of the test piece where the deflection occurred due to coating, to the maximum deflection, and the film thickness of the coated hard coating, and substitute that value into Equation 1. Thus, the residual compressive stress σ value of the entire hard coating was calculated. Even if the composition of the hard coating, the film forming conditions change, or the composition has a modulation structure, the value of the residual compressive stress can be calculated by this measurement method.

  When a hard film is formed on the substrate of the hard film-coated tool, a film forming method in which compressive stress is applied by applying a pulsed bias voltage is preferable. Specifically, an ion plating method such as an arc ion plating (hereinafter referred to as AIP) method or a sputtering method is preferable. If appropriate film forming conditions are applied, a composite apparatus in which each method is installed in one facility may be used. The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

  The surface of the test piece, the ball end mill and the throw-away insert capable of measuring the residual compressive stress was coated with the hard film according to the present invention to prepare the example 1 of the present invention. Here, as the ball end mill, a two-blade ball end mill having a diameter of 10 mm made of a WC-Co fine grain cemented carbide sintered body was used. As a throwaway insert, a general-purpose TNGG160404 shape was used, and a WC-Co cemented carbide sintered body was used as a base, and HRA90.5 corresponding to P20 type in the JIS standard was used.

  Invention Example 1 uses an AIP apparatus to form a (AlCr) N film having a composition of only metal components of Al: 70% and Cr: 30% as a first hard film on the substrate with a thickness of 4 μm. The film was formed. After that, as the second hard film, a (TiSi) N film of Ti: 80% and Si: 20% with a composition of only the metal component was formed to a thickness of 3 μm so that the total thickness was 7 μm. . The film formation temperature was 550 ° C., the reaction pressure was 3.5 Pa, and the initial (AlCr) N film was formed to a thickness of 1 μm with a DC bias voltage of DC 100 (V), and then a pulsed bias voltage was applied. The pulse frequency was 25 kHz, the negative bias voltage was set to -100 (V), and the positive bias voltage was set to 10 (V). After forming the (AlCr) N film of the first hard film, the (TiSi) N film of the second hard film is pulsed under the same conditions as the (AlCr) N film, and the negative bias voltage is set to −50 (V). The film was formed with a positive bias voltage set to 10 (V). The positive / negative time ratio at the time of pulse application was unified to 1: 1. As the evaporation source, various alloy targets are selected and used to form nitrides, carbonitrides, oxynitrides or oxycarbonitrides alone, or hydrocarbon gases such as nitrogen, oxygen and acetylene, or Then, they were mixed and introduced during film formation to form a film. Inventive Examples 2 to 9, 19 to 23, and 32 having different composition of hard coating, film thickness, X-ray diffraction peak intensity, interplanar spacing ratio, residual compressive stress and coating structure, with the film forming conditions of Inventive Example 1 as standard. To 43, Comparative 10 to 18, 24 to 30, and Conventional Example 31 were produced.

  Tables 1 to 3 show the measurement results of the hard coating conditions, the coating composition, the film thickness, the X-ray diffraction peak intensity ratio, the surface spacing ratio, and the residual compressive stress in each test piece. Table 4 shows the results of the observation of the structure of the film cross section with a transmission electron microscope (hereinafter referred to as TEM). It is confirmed that the second hard coatings in the examples of the present invention all have a columnar crystal structure, and the crystal grains of the columnar crystal structure have a composition modulation structure having a compositional difference in the Si component with respect to the crystal grain growth direction. did.

  Next, a cutting test was carried out using a two-blade ball end mill having a diameter of 10 mm made of a fine cemented carbide and a cemented carbide throw-away insert formed simultaneously with the test piece. In the evaluation by the ball end mill, the cutting test 1 was performed under the conditions of the following cutting test 1, and the superiority or inferiority of wear resistance, fracture resistance, and adhesion in a hard film having residual compressive stress was confirmed. In the evaluation method, in the observation of the cutting edge performed every time a certain distance was machined, when a defect including minute chipping of 10 μm or more occurred, when there was no defect, the VBmax value of the flank wear width reached 0.1 mm. The time was regarded as the tool life, and the performance was evaluated by the cutting time (minutes) at this time.

  In addition, a throw-away insert for turning is attached to a cutting edge replaceable bite, and a cutting test 2 is performed under the conditions of the following cutting test 2 to obtain superior or inferior wear resistance, fracture resistance, and adhesion in a hard film having residual compressive stress. It was confirmed. In the evaluation method, in the observation of the cutting edge performed every time a certain distance was machined, when a defect including minute chipping of 10 μm or more occurred, when there was no defect, the VBmax value of the flank wear width reached 0.3 mm. The time was regarded as the tool life, and the performance was evaluated by the cutting time (minutes) at this time. The damage state of the cutting edge during cutting was appropriately observed.

(Cutting test 1)
Tool: 2-flute ball end mill diameter 10mm
Work material: Martensitic stainless steel, HRC52
Cutting depth: 1.5mm in the axial direction x 0.1mm in the radial direction
Spindle speed: 12000 revolutions per minute Cutting speed: 377 m / min Table feed: 4 m / min Cutting oil: External mist supply

(Cutting test 2)
Tool: Throw-away insert for turning (TNGG160404 shape)
Cutting method: Longitudinal continuous cutting Workpiece shape: Round bar material with a diameter of 160 mm and a length of 600 mm: S53C, HB260, tempered material axial depth of cut: 2.0 mm
Cutting speed: 213 m / min Feed per rotation: 0.5 mm / rotating cutting oil: None

  Table 4 shows the evaluation results of the ball end mill, the insert cutting test 1, and the cutting test 2. First, Examples 1 to 9 and 19 to 23 of the present invention will be described. From Table 4, the results of the evaluation of Example 1 of the present invention were excellent in wear resistance, and stable processing could be carried out without causing peeling or chipping. Comparing Invention Example 2 and Invention Example 3, both satisfied the performance of the present invention, but Invention Example 1 was superior in cutting performance. The reason is that Example 1 of the present invention has the highest residual compressive stress and excellent wear resistance. In Example 4 of the present invention, the a value, which is the Al content of the first hard film, is 50% of the lower limit, and in Example 5, the e value, which is the Si content of the second hard film, is less than 5%. Although the cutting performance was inferior to that of Example 1 of the present invention, the performance of the example of the present invention was satisfied. This is because the residual compressive stress is reduced because the a and e values are near the boundary of the specified range. Invention Example 6 and Invention Example 7 contain Si in the first hard film, and the hardness of the first hard film was increased by the inclusion of Si. Hardness is obtained from measurement by the nanoindentation method. The film hardness of the first hard film of Invention Example 1 was 30.1 GPa, Invention Example 6 was 32.0 GPa, and Invention Example 7 was 35.2 GPa. Compared with Example 1 of the present invention, the cutting performance is equivalent, but since Si contained in Examples 6 and 7 of the present invention has very excellent oxidation resistance, a more advantageous effect can be expected in the region of high-temperature cutting. In Invention Example 8, since the film thickness of the first hard film was 6 μm, the residual compressive stress in the first hard film was larger than that in Invention Example 1, and the adhesion was inferior. In Example 9 of the present invention, since the film thickness of the second hard film was 4.1 μm, the residual compressive stress in the second hard film was increased, the film was liable to self-destruct, and the cutting stability was inferior.

  Inventive Examples 19 to 23 are the results of evaluating the influence of film forming conditions. Inventive Example 19 is the result of making the pulse frequency of the first hard film smaller than Inventive Example 1, and Inventive Example 20 is the result of making the pulse frequency of the second hard film smaller than Inventive Example 1. From Table 3, Invention Example 19 and Invention Example 20 have lower residual compressive stress than that of Invention Example 1, but have a high d1 / d2 value. Therefore, stable processing is possible, which is equivalent to Invention Example 1. Cutting performance was shown.

  In the inventive example 21, the negative bias voltage of the first hard film is lower than that of the inventive example 1, and in the inventive example 22, the negative bias voltage of the second hard film is lower than that of the inventive example 1. Since it was low, the residual compressive stress became low, and although the performance of this invention was shown, the cutting performance differed. In Invention Example 23, since the negative bias voltage of the second hard film was higher than that of Invention Example 1, the residual compressive stress was increased, and the columnar crystal structure became fine.

Examples 32 to 37 of the present invention will be described. Invention Examples 32 and 35 are obtained by introducing acetylene gas into nitrogen gas when forming the first hard coating. Inventive Examples 33 and 36 are oxygen gas, and Inventive Examples 34 and 37 are CO ₂ introduced. At this time, the total pressure combined with nitrogen gas was 3.5 Pa. It produced for the purpose of verifying the effect when N element of the non-metallic component of the first hard coating was partially substituted with C element and O element.

  As shown in Table 3, when the N element of the nonmetallic component of the first hard coating is substituted with the C element and the O element within a range of 10% or less in both atomic%, as in Invention Examples 32, 33, and 34 Tool life could be improved by improving oxidation resistance and lubrication characteristics.

  In Invention Example 38, the composition of only the metal component of the first hard coating is atomic%, Al: 66%, Cr: 34% (AlCr) N film, the composition of the second hard coating only of the metal component is Ti : (TiSi) N film of 85% and Si: 15%. The film thickness of the first hard film is 3.4 μm, the film thickness of the second hard film is 3.0 μm, and the first and second hard films of this film thickness are repeated three times as one cycle, and the total Films were formed to have 6 layers. Other film forming conditions were the same as those of Example 1 of the present invention. According to these film forming conditions, it was found that the residual compressive stress can be suppressed to 6 GPa or less even with a film thickness of 19.2 μm, and in particular, the cutting test 2 shows excellent wear resistance over a long period of time.

  Inventive Example 39 was subjected to metal bombardment prior to the formation of the first hard coating, and after forming the ultrathin TiC layer as an adhesion improving layer on the surface layer of the cemented carbide, the same conditions as in Inventive Example 1 The film was formed.

  Inventive Example 40, after forming a very thin TiN layer as an adhesion improving layer before forming the first hard coating, the film was formed under the same conditions as in Inventive Example 1. By coating the adhesion improving layer between the substrate of the cemented carbide and the first hard coating, the coating is less likely to peel off, stable wear progresses over a long period of time, and the tool has a long life. It was.

  In the inventive examples 41 to 43, the negative bias voltage of the first hard film was made higher than that of the inventive example 1. In this case, the higher the negative bias voltage, the greater the residual compressive stress of the hard coating, and the Is / Ir value tended to decrease from 3.38 to 1.27. From any of the cutting test results, the tool life was longer than that of the comparative example and the conventional example, and the cutting performance of the present invention was satisfied.

  Next, a comparative example will be considered. First, in Comparative Example 10, the composition of only the metal component of the first hard film is atomic%, Al: 82%, Cr: 18% (AlCr) N film, the second hard film is the composition of only the metal component, A (TiSi) N film of Ti: 83% and Si: 17% was formed under the same conditions as Example 1 of the present invention. It produced for the purpose of verifying the upper limit of the Al content in the coating composition of the first hard coating. Since the first hard film has a higher Al content than the examples of the present invention, the film structure of the first hard film became amorphous. As a result, the residual compressive stress increased, the adhesion strength decreased, and peeling occurred.

  In Comparative Example 11, the composition of only the metal component of the first hard coating is atomic%, Al: 45%, Cr: 55% (AlCr) N film, and the composition of the second hard coating only of the metal component is Ti: A (TiSi) N film of 82% Si: 18% was formed under the same conditions as Example 1 of the present invention. It produced for the purpose of verifying the lower limit of the Al content in the film composition of the first hard film. The first hard film had a lower Al content than that of the example of the present invention, and the proportion of Cr was increased, and the residual compression stress was higher than the appropriate range.

  In Comparative Example 12, the composition of only the metal component of the first hard coating is atomic%, Al: 65%, Cr: 35% (AlCr) N film, and the composition of the second hard coating only of the metal component is Ti: A 100% (Ti) N film was formed under the same conditions as in Example 1 of the present invention. It was produced for the purpose of verifying the lower limit of the Si content in the coating composition of the first hard coating. The second hard film did not contain Si, the film hardness of the second hard film was extremely low and the wear resistance was inferior, and the life was reached early.

  In Comparative Example 13, the composition of only the metal component of the first hard coating is atomic%, Al: 66%, Cr: 34% (AlCr) N film, and the composition of the second hard coating only of the metal component is Ti: A (TiSi) N film of 60% Si: 40% was formed under the same conditions as in Example 1 of the present invention. It produced for the purpose of verifying the upper limit of Si content in the film composition of the second hard film. The second hard film had a higher Si content than the examples of the present invention, and the film structure became amorphous. Due to the increased residual compressive stress, self-destruction of the hard coating occurred, leading to early tool life.

  In Comparative Example 14, the composition of only the metal component of the first hard film is atomic%, Al: 69%, Cr: 31% (AlCr) N film, and the composition of the second hard film only of the metal component is Ti: The 86% Si: 14% (TiSi) N film, the nitrogen pressure of the first hard film was 8.6 Pa, and the other conditions were the same as in Example 1 of the present invention. It produced for the purpose of verifying the lower limit of the c / d value of the first hard coating. When the c / d value of the first hard film was smaller than that of the example of the present invention, a large amount of gas components were taken into the first hard film and the bonds between the gas components increased, so that the crystal structure was amorphous. In this case, since the crystal structure was amorphous, the first hard film was difficult to grow epitaxially from the base material, the adhesion strength was reduced, and it was peeled off during the cutting process.

  In Comparative Example 15, the composition of only the metal component of the first hard film is atomic%, Al: 66%, Cr: 34% (AlCr) N film, and the composition of the second hard film only of the metal component is Ti: The 82% Si: 18% (TiSi) N film, the nitrogen pressure of the first hard film was 2.8 Pa, and the other conditions were the same as in Example 1 of the present invention. It produced for the purpose of verifying the upper limit of the c / d value of the first hard coating. When the first hard film has a larger c / d value than the example of the present invention, a large amount of metal components are taken into the first hard film, and the bond between the metal components is increased. A fine columnar structure was formed. In this case, since a large number of crystal grain boundaries exist, a lot of micro chipping occurs, which leads to tool chipping, which is considered to have shortened the tool life.

  In Comparative Example 16, the composition of only the metal component of the first hard coating is atomic%, Al: 69%, Cr: 31% (AlCr) N film, and the composition of the second hard coating only of the metal component is Ti: The 81% Si: 19% (TiSi) N film and the second hard film nitrogen pressure were 2.6 Pa, and the other conditions were the same as in Example 1 of the present invention. It was prepared for the purpose of verifying the upper limit of the f / g value of the second hard coating. When the second hard film has an f / g value larger than that of the example of the present invention, it exhibits an amorphous structure.

  In Comparative Example 17, the composition of only the metal component of the first hard coating is atomic%, Al: 65%, Cr: (AlCr) N film of 35%, and the composition of the second hard coating only of the metal component is Ti: The 86% Si: 14% (TiSi) N film, the nitrogen pressure of the first hard film was set to 8.3 Pa, and the other conditions were the same as in Example 1 of the present invention. It produced for the purpose of verifying the lower limit of the f / g value of the second hard coating. The second hard coating exhibits a columnar crystal structure when the f / g value is smaller than that of the example of the present invention, but the cutting test 1 showed a defect during the cutting.

  In Comparative Example 18, the composition of only the metal component of the first hard film is atomic%, Al: 58%, Cr: 24%, Si: 18% (AlCrSi) N film, and the second hard film is composed of only the metal component. A (TiSi) N film having a composition of Ti: 88% and Si: 12% was formed under the same conditions as in Example 1 of the present invention. It produced for the purpose of verifying the upper limit of the Si content effect and Si content in the 1st hard coat. The hardness of the first hard film was improved to 42.1 GPa, but the film structure became amorphous. As a result, the residual compressive stress was increased, the adhesion was deteriorated, and the hard coating was peeled off, resulting in an early tool life.

  In Comparative Example 24, the composition of only the metal component of the first hard film is atomic%, Al: 65%, Cr: 35% (AlCr) N film, and the composition of the second hard film only of the metal component is Ti: 81 %, Si: 19% (TiSi) N film, film formation conditions for the first hard film were negative bias voltage of −200 (V), and other conditions were formed under the same conditions as in Example 1 of the present invention. Is. The pulse frequency was 25 kHz, the film formation conditions for the second hard film were a negative bias voltage of −50 (V), a pulse frequency of 25 kHz, and a positive bias voltage of 10 (V). It produced for the purpose of verifying the upper limit of the negative bias voltage at the time of film-forming in a 1st hard film. When the first hard film was formed with a negative bias voltage value of −200 (V), the Is / Ir value was less than 0.5, and the residual compressive stress of the first hard film was increased. Therefore, the adhesiveness was lowered, and the tool life was reached early due to initial peeling or the like.

  In Comparative Example 25, the composition of only the metal component of the first hard film is atomic%, Al: 66%, Cr: 34% (AlCr) N film, and the composition of the second hard film only of the metal component is Ti: 83. %, Si: 17% (TiSi) N film, film formation conditions for the first hard film were negative bias voltage of −10 (V), and other conditions were formed under the same conditions as in Example 1 of the present invention. Is. The pulse frequency was 25 kHz, the film formation conditions for the second hard film were a negative bias voltage of −50 (V), a pulse frequency of 25 kHz, and a positive bias voltage of 10 (V). It produced for the purpose of verifying the lower limit of the film-forming bias voltage in a 1st hard film. When the first hard film was formed with a negative bias voltage value of −10 (V), the Is / Ir value exceeded 10.0, and the hardness of the first hard film was lowered. As a result, the wear resistance deteriorated and the tool life was reached early.

  In Comparative Example 26, the composition of only the metal component of the first hard film is atomic%, Al: 68%, Cr: 32% (AlCr) N film, and the composition of the second hard film only of the metal component is Ti: 82. %, Si: An 18% (TiSi) N film and the second hard film were formed under the same conditions as in Example 1 of the present invention except that the negative bias voltage was −10 (V) and the other conditions were the same. Is. The pulse frequency was 25 kHz, and the film forming conditions for the first hard film were a negative bias voltage of −100 (V), a pulse frequency of 25 kHz, and a positive bias voltage of 10 (V). It was produced for the purpose of verifying the lower limit of the film forming bias voltage in the second hard film. When the second hard film was formed with a negative bias voltage value of −10 (V), the film hardness was lowered and the wear resistance was deteriorated. Therefore, the tool had a short life.

  In Comparative Example 27, the composition of only the metal component of the first hard coating is atomic%, Al: 69%, Cr: 31% (AlCr) N film, and the composition of the second hard coating only of the metal component is Ti: 83. %, Si: 17% (TiSi) N film, and the second hard film were formed under the same conditions as in Example 1 of the present invention except that the negative bias voltage was −100 (V) and the other conditions were the same. Is. The pulse frequency was 25 kHz, and the film forming conditions for the first hard film were a negative bias voltage of −100 (V), a pulse frequency of 25 kHz, and a positive bias voltage of 10 (V). It produced for the purpose of verifying the upper limit of the film-forming bias voltage in a 2nd hard film. When the second hard film was formed with a negative bias voltage of −100 (V), the structure of the second hard film became amorphous and the film hardness improved, but the residual compressive stress increased. Therefore, delamination with the first hard film and self-destruction of the film occurred, leading to an early tool life.

  In Comparative Example 28, the composition of only the metal component of the first hard film is atomic%, Al: 65%, Cr: 35% (AlCr) N film, and the composition of the second hard film only of the metal component is Ti: 87. %, Si: 13% (TiSi) N film, the positive bias voltage when the bias voltage is pulsed is 2 (V), and other conditions are formed under the same conditions as in Example 1 of the present invention. is there. The film formation conditions for the first hard film are -100 (V) for a negative bias voltage and a pulse frequency of 25 kHz, and the film formation conditions for the second hard film are for a negative bias voltage of -50 (V) and a pulse frequency. The frequency was 25 kHz. It was fabricated for the purpose of verifying the lower limit of the positive voltage when the bias voltage was pulsed. When the film was formed with a positive voltage of 2 (V), the It / Ir value was less than 0.6, and as a result of an increase in internal defects of the film, defects occurred early and the tool life was reached.

  In Comparative Example 29, the composition of only the metal component of the first hard film is atomic%, Al: 63%, Cr: 37% (AlCr) N film, and the composition of the second hard film only of the metal component is Ti: 83. %, Si: (TiSi) N film of 17%, the positive bias voltage when the bias voltage is pulsed is 13 (V), and other conditions are formed under the same conditions as in Example 1 of the present invention. is there. The film formation conditions for the first hard film are -100 (V) for a negative bias voltage and a pulse frequency of 25 kHz, and the film formation conditions for the second hard film are for a negative bias voltage of -50 (V) and a pulse frequency. The frequency was 25 kHz. It was fabricated for the purpose of verifying the upper limit of the positive voltage when the bias voltage was pulsed. When the film was formed with a positive voltage of 13 (V), the It / Ir value exceeded 1.5, cracking was likely to occur, the effect of improvement was small, and the tool life from Conventional Example 31 was long. The difference could not be confirmed.

In Comparative Example 30, the composition of only the metal component of the first hard coating is atomic%, Al: 68%, Cr: 32% (AlCr) N film, the composition of the second hard coating only of the metal component is Ti: 85 %, Si: 15% (TiSi) N film, positive bias voltage when pulsing the bias voltage is 0 (V), and other conditions are the same as those of Example 1 of the present invention. is there. The film formation conditions for the first hard film are -100 (V) for a negative bias voltage and a pulse frequency of 25 kHz, and the film formation conditions for the second hard film are for a negative bias voltage of -50 (V) and a pulse frequency. The frequency was 25 kHz. It was fabricated for the purpose of verifying the effect of the application method during pulsing. When the positive voltage at the time of pulsing the bias voltage was set to 0 (V) and the film was formed with the unipolar bias, the It / Ir value was less than 0.6 as in Comparative Example 28. As a result of the increase in the internal defects of the film, defects occurred early and the lifetime was reached. Unipolar bias could not improve the wear resistance.

  In Conventional Example 31, the composition of only the metal component of the first hard coating is atomic%, Al: 66%, Cr: (AlCr) N film of 34%, and the composition of the second hard coating only of the metal component is Ti: 91. %, Si: 9% (TiSi) N film, the first hard film and the second hard film are not used for pulse bias but only DC DC bias is used, and other conditions are the same as those of Example 1 of the present invention. Was formed into a film. The film forming conditions for the first hard film were a negative bias voltage of −100 (V), and the film forming conditions for the second hard film were a negative bias voltage of −50 (V). It was produced for the purpose of verifying the effect of using the pulse bias in the present invention. When a film is formed using only a direct current DC bias, the residual compressive stress is very high, self-destruction and delamination occur, and the life is reached early.

  The hard film-coated tool of the present invention is further optimized in the balance between wear resistance and toughness even when a high-speed tool steel base, cermet, or the like is employed in addition to the tungsten carbide base cemented carbide as the base. However, when high-speed tool steel is used as the substrate, it is preferable to coat in the range of 400 to 450 ° C. in consideration of its heat treatment characteristics. When forming a film at such a relatively low temperature, it is necessary to appropriately optimize the bias voltage to be applied and the reaction pressure at the time of film formation.

Claims (5)

In a hard film coated tool in which a hard film having a compressive stress is coated on a substrate with a cemented carbide alloy in a film thickness of 3 to 20 μm, the hard film is coated with a first hard film and a second hard film in order from the substrate side, The first hard coating and the second hard coating are alternately coated with at least one layer, and the first hard coating is represented by (Al _a Cr _1-ab Si _b ) _c N _d , provided that a and b is atomic%, c and d represent atomic ratios, 50 ≦ a ≦ 70, 0 ≦ b <15 and 0.85 ≦ c / d ≦ 1.25, and the second hard coating is (Ti _1-e Si _e ) _f N _g where e is atomic%, f and g represent atomic ratios, 1 ≦ e ≦ 20 and 0.85 ≦ f / g ≦ 1.25 The crystal structures of the first hard film and the second hard film are both face-centered cubic structures, and X of the first hard film In the diffraction, 1.0 ≦ Is / Ir ≦ 10.0 and 0. 0 when the peak intensity of the (111) plane is Ir, the peak intensity of the (200) plane is Is, and the peak intensity of the (220) plane is It. 6 ≦ It / Ir ≦ 1.5, and when the distance (nm) between the (200) planes in the X-ray diffraction of the first hard coating and the second hard coating is d1 and d2, respectively. 0.965 ≦ d1 / d2 ≦ 0.990, the second hard film has a columnar crystal structure, and the crystal grains of the columnar crystal structure have a composition modulation structure having a compositional difference in the Si component. Hard film coated tool.   2. The hard coating tool according to claim 1, wherein the X-ray diffraction of the second hard coating has a (111) plane peak intensity as Iu, a (200) plane peak intensity as Iv and a (220) plane peak intensity. A hard film coated tool characterized by 1.0 ≦ Iv / Iu ≦ 10.0 and 1.0 ≦ Iw / Iu ≦ 1.5 when Iw.   The hard film-coated tool according to claim 1, wherein a part of the N element in the first hard film is replaced with one or two elements of C element and O element, and the entire nonmetallic component is replaced. 100 atomic%, where C is the content of C and x is the content of C element and y is the content of O element, 0 <x ≦ 10, 0 <y ≦ 10 and 0 <x + y ≦ 10. Content is 100-xy, The hard film coating tool characterized by the above-mentioned.   4. The hard film-coated tool according to claim 1, wherein when the film thickness of the first hard film is T1 (μm) and the film thickness of the second hard film is T2 (μm), 0. A hard film-coated tool, wherein 1 ≦ T1 <5.0 and 0.1 ≦ T2 <4.0, and the second hard film is the uppermost layer.   5. The hard film-coated tool according to claim 1, wherein a Ti layer or a Ti-based nitride, carbide and carbonitride is provided between the cemented carbide substrate and the first hard film. A hard-coated tool having an adhesion improving layer composed of one or more selected, wherein the adhesion improving layer has a thickness of 1 μm or less.