JP5056808B2 - Hard coating tool - Google Patents

Description

  The present invention relates to a hard film-coated tool used for processing metal parts and the like. In particular, the present invention relates to a hard film-coated tool in which a hard film is coated on a tool surface that requires wear resistance and adhesion using physical vapor deposition (hereinafter referred to as PVD method).

  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 the orientation of the (111) 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 4 discloses a technique for controlling peak intensities on the (220) plane and the (111) plane. Patent Document 5 discloses a technique for adjusting the constituent ratio of a metal element and a gas component element constituting a hard coating. Patent Document 6 discloses a technique related to improvement in adhesion at a film interface by epitaxial growth.

JP 2003-136302 A JP 2003-145313 A JP 2006-281363 A JP 2003-71611 A JP-A-7-188901 JP 2001-181826 A

  However, in any of Patent Documents 1 to 6, the present invention is a hard film constituted by laminating a first hard film containing Al and a (TiB) N-based second hard film according to the present invention, The composition, X-ray orientation and microstructure of the hard film are appropriately selected and controlled to notably improve or improve the tool life and the like.

  Accordingly, the present invention provides a new high-performance hard film-coated tool that improves adhesion by reducing the compressive stress in a hard film that has been thickened, and has excellent wear resistance by increasing the hardness of the hard film surface. With the goal.

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 alloy in a film thickness of 5 to 30 μm. The second hard film is coated, and the outermost film is coated with the second hard film. The composition of the first hard coating is (Al _a Me _100-a ) _e N _f (where a is atomic%, e and f represent atomic ratios, respectively 35 ≦ a ≦ 65, and 0.85) ≦ e / f ≦ 1.25, Al is aluminum, Me is at least one element selected from groups 4a, 5a, and 6a, Si and B, and N is nitrogen. And
The composition of the second hard coating is (Ti _100-h B _h ) _m N _p (where h is atomic%, m and p represent atomic ratios, respectively, 0 <h ≦ 30, and 0.90) ≦ m / p ≦ 1.15, Ti is titanium, B is boron, and N is nitrogen.)
The crystal structures of the first hard film and the second hard film are face-centered cubic structures, respectively.
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, 1.5 ≦ Is in the X-ray diffraction of the first hard film. /Ir≦15.0 and 0.6 ≦ It / Ir ≦ 1.5, and in the X-ray diffraction of the second hard film, 0.2 ≦ Is / Ir ≦ 1.0 and 0.6 ≦ It /Is≦1.5,
In the X-ray diffraction of the first hard film and the second hard film, 1.00 ≦ d2 / d1 ≦ 1.03, where d1 and d2 are plane distances (nm) on the surface having the highest intensity, respectively. Yes,
The second hard film has a columnar structure, and the crystal grains of the columnar structure have a composition modulation structure having a composition difference in the B component.
According to the present invention, it is possible to provide a hard film-coated tool that has improved adhesion by reducing compressive stress in a hard film that has been increased in thickness, and that has excellent wear resistance due to increased hardness of the surface of the hard film.

In the hard film-coated tool of the present invention, a part of the nonmetallic component nitrogen (N) in the first hard coating is replaced with carbon (C) and / or oxygen (O), and the entire nonmetallic component is 100%. Assuming that the atomic% is carbon content and the oxygen content is x and the oxygen content is y, 0 <x ≦ 10, 0 <y ≦ 10, 0 <x + y ≦ 10, and the nitrogen content is (100 -Xy) is preferred.
Further, a part of the metal component titanium (Ti) in the second hard film is replaced with silicon (Si), the entire metal component is 100 atomic%, and the silicon content is k in atomic%. When 0 <k ≦ 20, the content of titanium is preferably (100−h−k). The hard film having a compressive stress preferably has a total film thickness of 10 μm to 30 μm.

  According to the present invention, it is possible to provide a hard film-coated tool having improved adhesion by reducing the compressive stress in a hard film having a thick film and having excellent wear resistance by increasing the hardness of the surface of the hard film.

  The hard film employed by the hard film-coated tool of the present invention has a first hard film and a second hard film.

<First hard coating>
The composition of the first hard coating is represented by (Al _a Me _100-a ) _e N _f .
In the composition formula, the ratio between Al and Me elements is indicated in atomic percent in parentheses, and the ratio between (AlMe) and N is indicated in atomic ratios outside the parentheses. When the value a representing the aluminum (Al) content is in the range of 35 ≦ a ≦ 65 atomic%, the heat resistance and wear resistance are excellent. If the a value exceeds 65 atomic%, the first film cross-sectional structure becomes finer, the compressive stress increases, and there is a disadvantage that the adhesion with the substrate deteriorates. When the a value is less than 35 atomic%, there is a disadvantage that the wear resistance is inferior.
The Me component collectively referred to as the element Me includes elements 4a, 5a, and 6a having an ionic radius of 0.041 to 0.1 nm, silicon (Si) having an ionic radius of 0.002 to 0.04 nm, It is preferable to coat as a nitride containing boron (B) or the like. This is because there is a difference between the ionic radius of the Me component, silicon or boron, and the ionic radius of the aluminum element, and stress acts on the crystal structure, which is convenient for increasing the hardness of the film. By selecting, for example, titanium (Ti) as the Me component, it is effective for increasing the hardness of the first hard coating. For example, when Me is silicon (Si) or boron (B), the content range for maintaining the solid solution is 1 to 20 atomic%, and excellent heat resistance and lubrication characteristics can be obtained. In addition, containing W, Nb or Cr as Me is effective in improving the heat resistance and hardness of the first hard coating.

  By setting the ratio e / f 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 extremely high adhesion Can be obtained. Further, when the e / f value is 0.85 to 1.25, the structure of the first hard film can be a columnar structure having high toughness, and excellent chipping and wear resistance can be obtained. When the e / f value is 0.85 or more, the crystal lattice strain of the first hard film can be reduced. However, when the e / f value is less than 0.85, the crystal lattice strain increases and the continuity of crystal lattice fringes is lost. The cross-sectional structure of the first hard coating becomes finer and the grain boundary defects increase. As a result, the compressive stress increases and the adhesion deteriorates. For example, in hard coatings for cutting tools, this grain boundary defect reduces the density of the hard coating, and the elements that make up the workpiece enter this grain boundary and cause inward diffusion into the hard coating. It significantly deteriorates the mechanical properties of the hard film, such as a decrease in film hardness, oxidation resistance, and fracture resistance. When the e / f value exceeds 1.25, the first hard film has a columnar structure, but it is easy to incorporate impurities into the crystal grain boundary. This impurity is a component remaining inside the apparatus that performs the coating process. As a result, the bonding strength between the crystal grains deteriorates, and the first hard film is easily broken by an external impact, or the elements constituting the workpiece enter the grain boundary and enter the hard film. Inward diffusion is caused, resulting in a decrease in the hardness of the hard coating and deterioration in mechanical properties such as oxidation resistance. By setting the first hard coating of the present invention in the range of 0.85 ≦ e / f ≦ 1.25, the compressive stress of the first hard coating is in the range of 1.5 to 5.0 GPa. Industrially, by setting the e / r value within the range of the present invention, it is possible to manage the first hard coating within a range where the compressive stress is not excessive while having the compressive stress.

<Second hard coating>
The composition of the second hard coating is represented by (Ti _100-h B _h ) _m N _p .
In the composition formula, the ratio between Ti and B is expressed in atomic% inside the parentheses, and the ratio between (TiB) and N is expressed by atomic ratio outside the parentheses. When the second hard film is a nitride having a face-centered cubic structure containing Ti and B, excellent welding resistance and crater wear resistance can be realized. The h value (atomic%) indicating the B content in the second hard film is 0 <h ≦ 30, and preferably 1 ≦ h ≦ 30. This range of h values is important for making the second hard coating a columnar structure. Moreover, when B element is contained, the wear resistance of the rake face of the tool is improved. In the initial stage of cutting, B is oxidized from the state where the tool edge is still at a low temperature to form a B-containing oxide. This B-containing oxide exhibits the effect of suppressing diffusion of the workpiece component into the second hard coating. However, when the h value exceeds 30 atomic%, the structure of the second hard coating becomes finer. In addition, boron nitride (BN) crystals appear and the hardness is lowered, and the compressive stress of the second hard film is increased, resulting in a drawback that adhesion is lowered. The effect appears even when the h value is about 1 atomic%.

  Moreover, by setting the ratio m / p value of the metal component and the nitrogen component of the second hard coating to 0.90 to 1.15, the compressive stress of the second hard coating can be in an optimum range, and high resistance Abrasion can be obtained. Further, when the m / p value is 0.90 to 1.15, the second hard film can be a columnar structure having high toughness, and excellent defectability 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 as a whole film and excellent in wear resistance can be obtained.

<Production conditions>
Below, the manufacturing conditions for obtaining the specific composition and structure | tissue of the hard film which this invention employ | adopts are demonstrated.
In the first hard coating (Al _a Me _100-a ) _e N _f , it is important to control the reaction pressure during film formation in order to make the range 0.85 ≦ e / f ≦ 1.25. It is. In order to obtain nitride, the reaction pressure of nitrogen is set to 2 Pa to 8 Pa. More preferably, it is good to set it as the range of 2.5Pa-5Pa. When the reaction pressure is less than 2 Pa, the kinetic energy of ions incident on the substrate cannot be suppressed, which appears as crystal lattice strain, the compressive stress cannot be suppressed, and the e / f value is less than 0.90. When film formation is performed under conditions exceeding 8 Pa, the plasma density is lowered, the kinetic energy of incident ions is significantly lowered, and the e / f value exceeds 1.15.

  As a condition for forming the first hard film, the pulsed bias voltage application is negatively and positively amplituded and strongly oriented in the (200) plane, which is high in suppressing the compressive stress of the first hard film. Adhesion can be realized. For this purpose, the bias voltage application can be realized by making the amplitude between a negative 30-100 V and a positive voltage 5-10 V.

In order to make the range of 0.90 ≦ m / p ≦ 1.15 in (Ti _100-h B _h ) _m N _p , which is the second hard film, it is important to control the reaction pressure during film formation. It is. In order to obtain a nitride, the reaction pressure of nitrogen is set to 0.5 Pa to 3.5 Pa. More preferably, it is good to set it as the range of 1.0 Pa-3.5 Pa. When the reaction pressure is less than 1.0 Pa, the kinetic energy of ions incident on the substrate cannot be suppressed, which appears as crystal lattice strain, and the compressive stress cannot be suppressed, and the m / p value is less than 0.90. . When film formation is performed under conditions exceeding 3.5 Pa, the plasma density decreases, the kinetic energy of the incident ions decreases significantly, and the m / p value exceeds 1.15.

  As a condition for forming the second hard film, the pulsed bias voltage application is negatively and positively amplituded and strongly oriented in the (111) plane, which is high in suppressing the compressive stress of the second hard film. Abrasion resistance can be realized. For this purpose, the bias voltage application can be realized by making the amplitude between negative 100 to 200V and positive voltage 5 to 10V.

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, the Is / Ir value of the first hard coating is 1.5 ≦ Is. In order to satisfy /Ir≦15.0, it is necessary to control the bias voltage, and it is preferable to apply the bias voltage in a pulsed manner. When the bias voltage is less than minus 30 V, the Is / Ir value tends to increase and the compressive stress is reduced, but the hardness of the first hard film is lowered and the wear resistance is deteriorated. Furthermore, since the kinetic energy of incident ions is significantly reduced, high adhesion cannot be obtained. When a film is formed by applying a negative bias voltage higher than minus 100 V, the kinetic energy of incident ions increases. That leads to an increase in compressive stress.
The compressive stress is also affected by the film thickness of the first hard coating. That is, the thicker the film, the more the compressive stress tends to increase. The first hard film having a face-centered cubic structure adopted by the present invention was strongly oriented in the (200) plane to form a thick film. However, when the thickness of the first hard coating is increased, the compressive stress is remarkably increased, and high adhesion to the substrate cannot be obtained even if the first hard coating is strongly oriented in the (200) plane. Therefore, it is necessary to adjust the kinetic energy when the element constituting the first hard film ionized in the plasma at the time of film formation reaches the substrate by applying a pulsed bias voltage. The control of the pulse frequency is particularly important when the bias voltage is pulsed. When the bias voltage is applied in a pulsed manner, the peak intensity of the (111) plane, (200) plane, and (220) plane can be changed, particularly by promoting crystal growth on the (200) plane. In addition, the compressive stress can be suppressed and the adhesion can be improved, and further excellent chipping properties and wear resistance can be obtained.
Since the first hard coating is a hard coating composed of a plurality of elements having different ionic radii, distortion occurs in the face-centered cubic structure. This is one of the causes of increased compressive stress. If the (111) plane, which is the top-filled atomic plane of the face-centered cubic structure, is strongly oriented, slip occurs due to an increase in compressive stress on the (111) plane, and as a result, the structure of the hard coating becomes finer. The fine structure causes an increase in grain boundaries, and oxidation is promoted by oxygen entering from the outside into the grain boundaries. In addition, when an impact is applied from the outside in cutting or the like, the grain boundary breakage easily occurs. The intergranular fracture is more likely to occur at the interface between the base material and the hard film, and as a result, the adhesiveness is lowered. When strongly oriented in the (200) plane, the number of grain boundaries can be reduced, and a coarse columnar structure can be obtained, so that when subjected to external impacts in cutting or the like, the durability in the shear direction is particularly excellent. Therefore, it is considered that the strength of the hard coating is increased, and the deficiency and adhesion are increased.

  When the pulse frequency is 5 to 25 kHz, the It / Ir value is 0.6 ≦ It / Ir ≦ 1.5, and the compressive stress of the first hard film at this time is in an optimum range of 2.0 to 6.0 GPa. Can be. When the pulse frequency is lower than 5 kHz, the It / Ir value exceeds 1.5. If it exceeds 25 kHz, the kinetic energy when ions reach the substrate cannot be adjusted, and the It / Ir value becomes less than 0.6.

  If the bias voltage applied when forming the second hard film is pulsed in the same manner as the conditions for forming the first hard film, the kinetic energy of boron (B) ions reaching the substrate can be adjusted. Incorporated into the crystal lattice of titanium nitride (typically referred to as TiN), the second hard coating has a single crystallized structure containing B.

  On the other hand, when the second hard film is formed by applying a DC bias voltage, B is replaced by a lattice of TiN face-centered cubic structure, cubic boron nitride (c-BN), hexagonal crystal In many cases, the second hard film contains boron nitride (h-BN), amorphous BN, or the like. Since ions of B in the plasma are lighter elements than Ti and the like, it is considered that the ions reach the substrate with high kinetic energy and various unstable bonds are generated. When only the h-BN is included in the second hard coating, it is expected that the lubrication characteristics are improved and the rake face wear can be suppressed, but it is difficult to contain h-BN alone. Since it comes to coexist with compounds having other crystal structures such as c-BN, the compressive stress increases. In particular, when a large amount of c-BN is contained, although it is possible to increase the hardness of the second hard coating, it is not preferable because the compressive stress increases and the adhesion deteriorates. Furthermore, crystal grain boundaries increase and the structure of the hard coating becomes finer. As a result, oxidation resistance and shear strength deteriorate.

  Next, among the constituent features of the present invention, the (200) plane peak intensity condition important in the first hard coating will be described. In the present invention, when the first hard film having a face-centered cubic structure is evaluated by X-ray diffraction, it is a great feature that it is most strongly oriented in the (200) plane. Due to this feature, in the present invention, the first hard film has high adhesion, and the durability against cutting force from the shear direction in cutting is excellent.

  Generally speaking, the hard coating is destroyed (hereinafter referred to as a crack) in response to an external impact caused by cutting. The crack propagates through the grain boundary of the structure in the hard film in the direction perpendicular to the base, reaches the base, and causes cracks and wear. Therefore, when the orientation to the (200) plane in the first hard film in contact with the base becomes strong, the compressive stress is reduced and the adhesion of the first hard film is increased. However, when the orientation to the (111) plane becomes stronger, the first hard film becomes harder, but the adhesion deterioration due to the increase of the compressive stress and the oxidation resistance and mechanical strength due to the refinement of the structure decrease. Inconvenience occurs.

  Like the present invention, by strongly orienting the first hard film in the (200) plane, the propagation of cracks generated in the direction perpendicular to the substrate is reduced, and the wear resistance is increased. In particular, since the compressive stress can be reduced, high adhesion can be obtained. Therefore, in the present invention, in the X-ray diffraction of the first hard film, 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, The Is / Ir value of one hard coating is defined as 1.5 ≦ Is / Ir ≦ 15.0, and the It / Ir value is defined as 0.6 ≦ It / Ir ≦ 1.5. If the first hard film is 1.5 ≦ Is / Ir ≦ 15.0, excellent adhesion can be realized, and if 0.6 ≦ It / Ir ≦ 1.5, the range of appropriate compressive stress is achieved. Can be obtained. Therefore, the first hard film having high mechanical strength can be obtained while the thick film has high adhesion. However, when the Is / Ir value is less than 1.5 and the It / Ir value is less than 0.6, the cross-sectional structure of the first hard coating is remarkably refined and the compressive stress increases. For this reason, the wear resistance in a use environment with a small load is excellent, but when the load increases, the film peels easily. In particular, when the It / Ir value is less than 0.6, the internal defects of the first hard coating increase. When the It / Ir value is less than 0.6, it is difficult to control the compressive stress of the first hard film even if the Is / Ir value is 1.5 ≦ Is / Ir ≦ 15.0. It becomes. At this time, the compressive stress of the first hard film is about 6.5 GPa, and the adhesion between the substrate and the first hard film is remarkably deteriorated. Therefore, it is defined as 0.6 ≦ It / Ir ≦ 1.5. When the Is / Ir value is larger than 15.0 and the It / Ir value is larger than 1.5, the compressive stress is reduced and the adhesion to the substrate is increased. However, on the other hand, the hardness is significantly reduced and the wear resistance is poor. In addition, the bonding strength at the grain boundaries in the cross-sectional structure of the hard coating is reduced, and the fracture resistance is deteriorated.

  Next, among the constituent features of the present invention, the (111) plane peak intensity condition important in the second hard coating will be described. A major feature of the present invention is that when the first hard film having a face-centered cubic structure is X-ray diffracted, the second hard film is most strongly oriented in the (111) plane. Due to this feature, in the tool of the present invention, the second hard film has excellent wear resistance, and particularly crater wear is excellent.

  Like the present invention, crater wear is particularly excellent by orienting the second hard coating strongly on the (111) plane. This is a hard film adopted by the present invention, and the second hard film having a face-centered cubic structure which is the outermost surface is strongly oriented to (111) which is the most filled surface of the atom, in particular, the cutting force in the shear direction. On the other hand, by generating the slip, it is possible to suppress the crack propagation in the direction perpendicular to the substrate. As a result, wear resistance is excellent. Therefore, in the present invention, in the X-ray diffraction of the second hard film, 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, 2 The Is / Ir value of the hard coating is defined as 0.2 ≦ Is / Ir ≦ 1.0, and the It / Is value is defined as 0.6 ≦ It / Is ≦ 1.5. Excellent abrasion resistance can be realized when 0.2 ≦ Is / Ir ≦ 1.0 in the second hard film, and an appropriate compression stress range is obtained when 0.6 ≦ It / Is ≦ 1.5. Can be obtained, the mechanical strength of the hard coating is increased, and excellent chipping properties can be obtained. Therefore, it is possible to obtain a second hard film in which the thickened film has excellent wear resistance and fracture resistance. However, when the Is / Ir value is less than 0.2 and the It / Is value is less than 0.6, the second hard film is highly hardened, but the cross-sectional structure is remarkably refined and the compressive stress is increased. For this reason, the wear resistance in a use environment with a small load is excellent, but when the load increases, the film peels easily. In particular, when the It / Is value is less than 0.6, the internal defects of the second hard coating increase. When the It / Is value is less than 0.6, the compressive stress of the second hard film can be controlled even if the Is / Ir value is 0.2 ≦ Is / Ir ≦ 1.0. It becomes difficult. At this time, the compressive stress of the entire second hard film becomes about 7 GPa, which causes a significant deterioration in the adhesion between the base and the first hard film. Therefore, it is defined as 0.6 ≦ It / Is ≦ 1.5. When the Is / Ir value is larger than 1.0 and the It / Is value is larger than 1.5, the compressive stress is reduced and the adhesion to the substrate is increased. However, on the other hand, the hardness is significantly reduced and the wear resistance is poor. In addition, the bonding strength at the grain boundaries in the cross-sectional structure of the hard coating is reduced, and the fracture resistance is deteriorated. When a hard film having a crystal grain boundary with reduced bonding strength is used for a cutting tool, oxygen enters the crystal grain boundary, the oxidation of the hard film is promoted, and the wear resistance is remarkably deteriorated. In addition, the workpiece tends to diffuse and the mechanical properties of the hard coating are significantly degraded.

  When the pulse frequency is 5 to 25 kHz, the It / Is value is 0.6 ≦ It / Is ≦ 1.5. At this time, the compressive stress of the second hard film alone is 2.0 to 3.0 GPa. The compressive stress of the entire hard coating adopted by can be adjusted to an optimum range of 3.0 to 6.0 GPa. When the pulse frequency is lower than 5 kHz, the It / Is value exceeds 1.5. If it exceeds 25 kHz, the kinetic energy when ions reach the substrate cannot be adjusted, so the It / Is value is less than 0.6.

  In the hard coating according to the present invention, in the X-ray diffraction of the first hard coating and the second hard coating, the surface interval (nm) of the (200) plane of the first hard coating is d1, and the second hard coating When the distance (nm) between the (111) planes is d2, the d2 / d1 value is set to 1.00 ≦ d2 / d1 ≦ 1.03, so that the first hard film and the second hard film Adhesion is enhanced, and the second hard coating having high hardness is excellent in wear resistance, particularly crater wear. In order to improve the adhesion between the hard films, it is necessary to reduce the crystal lattice strain. In order to reduce this distortion, high adhesion can be obtained by reducing the difference in the interplanar spacing between the most strongly oriented surfaces of the first and second hard coatings to reduce the interface misfit. Therefore, by defining the d2 / d1 value in the range of 1.00 ≦ d2 / d1 ≦ 1.03, a hard coating having high adhesion and excellent wear resistance can be obtained. When the d2 / d1 value is less than 1.00, the strain at the interface between the first and second hard films increases, which increases the compressive stress of the entire hard film. As a result, the adhesion with the substrate is also deteriorated. If it exceeds 1.03, the strain at the interface between the first and second hard coatings increases, which increases the compressive stress of the entire hard coating. As a result, the adhesion with the substrate is also deteriorated. As an example of the film forming condition, the method of setting the range of 1.00 ≦ d2 / d1 ≦ 1.03 is to use the pulse frequency in the pulse bias application, which is the film forming condition, in the range of 2 kHz to 35 kHz, and to use the bipolar bias. Adopt and set the positive bias value from 5V to 30V.

  Regarding the hard film according to the present invention, the second hard film has a columnar structure, and the crystal grains are continuously grown in the boundary region between the crystal grains without forming an interface with respect to the crystal grain growth direction. . Here, the columnar structure is a vertically grown crystal structure extending in the film thickness direction. The second hard film is a polycrystalline material, but has a form similar to the growth of a single crystal material when grasped in units of crystal grains. As a feature of the present invention, the crystal grains of the columnar structure have a composition modulation structure having a composition difference in the B component with respect to the crystal grain growth direction. At this time, it is preferable that crystal lattice fringes are continuous at the composition modulation boundary in the composition modulation structure. The second hard film has a B component composition modulation structure, and the mechanical strength is increased by controlling the compressive stress. For example, a B layer enriched layer forms a relatively soft layer. If this soft layer is present between other relatively hard layers, it is considered that a buffering effect is exhibited, and the compressive stress is relieved as a whole of the second hard film. Furthermore, the 2nd hard film | membrane which has lubricity can be obtained with the lubrication characteristic of B component. Further, by containing the B component, the thermal conductivity is increased, and a hard film particularly excellent in crater wear can be obtained. However, the preferable composition difference of the B component at this time is 10 atomic% at the maximum. More preferably, it is in the range of 0.1 atomic% or more and 7 atomic% or less.

  The composition modulation structure of the B component can be realized by performing film formation while applying a pulse bias using targets having different B contents. The second hard coating according to the present invention can be realized by applying a high bias voltage by a pulse bias. Therefore, in particular, in the second hard coating, since B having an ion radius smaller than that of Ti is contained in the crystal lattice of the face-centered cubic structure TiN, it is necessary to control the kinetic energy of ions by applying a pulse bias. This is because it becomes difficult to contain B in the second hard film when a high DC bias voltage is applied. By applying a pulse bias, a portion where the B content in the columnar structure has a composition difference becomes a composition-modulated structure, and crystal lattice fringes continuously grow between the layers. The composition modulation structure in which the crystal lattice fringes between the layers are continuously grown has an acceleration voltage of 20 kV using, for example, a JEM-2010F type field emission transmission electron microscope (hereinafter referred to as TEM) manufactured by JEOL Ltd. This can be confirmed by observing the columnar structure under conditions.

  By setting the film thickness of the entire hard coating to 5 μm or more, excellent wear resistance can be obtained. On the other hand, if it exceeds 30 μm, the hard coating film has a high compressive stress and deteriorates the adhesion to the substrate, so that it is preferably 30 μm or less. Further, the film thickness of the first hard film is thicker than that of the second hard film, and more preferably, the film thickness of the second hard film is 50% or less with respect to the film thickness of the entire hard film. More preferably, when the hard film has a film thickness of 10 μm to 30 μm, excellent wear resistance can be obtained.

The nitrogen element of the non-metallic component in the first hard coating is partially substituted with carbon and oxygen, and when the carbon content is x value and the oxygen content is y value in atomic%, 0 <x ≦ Preferably, the ranges are 10, 0 <y ≦ 10, and 0 <x + y ≦ 10. Thereby, the 1st hard film which has high hardness, the outstanding oxidation-resistant characteristic, adhesiveness, and a lubrication characteristic is obtained. When carbon and oxygen are contained in the specific amounts, in order to avoid deterioration of mechanical strength, the sum of the x value and the y value is 10 atomic% or less, so that excellent welding resistance and slidability are achieved. Have. More preferably, when carbon is contained singly, the content is 2 atomic% to 10 atomic%. However, when the x value and the y value exceed 10 atomic%, the crystal structure becomes finer and defects at the grain boundaries increase. As a result, even if the lubrication characteristics of the first hard coating are improved, the compressive stress increases, and thus a defect that adhesion and fracture resistance are lowered appears. When carbon and oxygen are contained in the first hard film, it is preferable to use a hydrocarbon-based gas or an oxygen-containing gas. When film formation is performed by introducing gas, the total pressure combined with nitrogen gas is preferably in the range of 2 to 8 Pa. When carbon is added to form a film by introducing a gas, it is easier to control using nitrogen (N ₂ ) and methane (CH ₄ ) or ethylene (C ₂ H ₆ ). In the case of introducing a hydrocarbon gas, up to about 20% by volume with respect to the nitrogen flow rate is a range in which film formation can be performed stably. In the case of introducing oxygen gas, it is preferable to perform film formation by introducing nitrogen gas and oxygen gas, or nitrogen gas, oxygen gas, and argon. Alternatively, the target evaporation source can be contained as a compound containing carbon and oxygen.

  Regarding the Ti element of the metal component in the second hard coating, a part thereof is substituted with Si element, and when the whole metal component is 1, when the content of Si element is k in atomic%, 0 <k ≦ By setting it to 20, the wear resistance is improved. In order to make the second hard coating have a columnar structure, the k value is preferably 20 atomic% or less. When Si is contained, the second hard coating having excellent wear resistance in crater wear on the rake face of the cutting tool can be obtained, for example, by forming a single crystal of TiN as a solid solution. On the other hand, if the k value exceeds 20 atomic%, the structure becomes finer, the compressive stress increases, and the disadvantage of decreasing the adhesion appears. In addition, the second hard coating includes various structures in the form of TiN crystalline, SiN composition crystalline, or amorphous. As a result, crystal grain boundaries increase, crystal lattice distortion occurs, and compressive stress increases.

  The composition of the hard coating employed by the present invention can be measured, for example, using a JXA8500F type EPMA analyzer manufactured by JEOL. Specifically, in the vertical cross section of the hard film or the inclined cross section obtained by inclining the film cross section at an angle of 17 degrees, the hard film is applied from a position not affected by the substrate, the acceleration voltage is 10 kV, the irradiation current is 1.0 μA, the probe diameter. The composition can be specified by setting the thickness to about 5 μm. When measuring from the surface of the hard coating, the probe diameter is preferably set to about 50 μm. Further, when carbon or oxygen is contained, if it is less than 2 atomic%, detection by analysis becomes difficult. The film thickness of the hard coating can be measured, for example, by observing the fracture surface in the vertical direction at a magnification of 25,000 times, for example, using an S-4200 type electrolytic emission 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 first and second hard coatings is performed using, for example, a RU-200BH type X-ray diffractometer manufactured by Rigaku Corporation. It can be measured by the 2θ-θ scanning method. In the embodiment of the present invention, the range of 2θ (degrees) is 10 to 145 degrees, the X-ray source is CuKα1 line having a λ value of 0.15405 nm, and background noise is 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 of each index surface was taken as the peak intensity, and the peak intensity ratio was determined using the maximum value. Furthermore, the numerical value of the peak position which shows the said (111) and (200) plane was applied to the surface space | interval. Further, the peak intensity was measured in the same manner for the first hard coating based on CrN.

  The compressive stress in the hard film according to the present invention can be calculated by the following curvature measurement method. 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 is coated on the surface, the coated test piece is caused by the compressive stress generated in the hard film. Deforms and deforms. The amount of deflection deformation is obtained, and the numerical value 1 is used to calculate the compressive stress σ value of the entire hard coating. In Examples and the like described later, numerical values calculated by this method are described.

  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 part, νs value is the Poisson's ratio of the substrate used for the test piece, and d (μm) is coated on the surface of the test piece. It is 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. For example, when a shape having a width of 8 mm, a length of 25 mm, and a thickness of 0.5 to 1.5 mm is used, variation in measured numerical values is small. 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., and particularly the surface portion of the material used for the test piece. It is important to remove the distortion. Unless this strain is removed to some extent, the resulting compressive stress values will vary. After measuring the deflection deformation amount of one mirror-finished surface having a large test piece area before coating, the surface is coated, and the deflection amount of the obtained coated test piece is measured again. Measure the amount of deflection before and after coating, the length from the end face in the length direction of the test piece where the deflection occurred to the maximum deflection, and the film thickness of the coated hard coating. For example, it is possible to calculate the value of the compressive stress even if the composition of the hard film and the film forming conditions are changed or the composition has a modulation structure.

  When the hard coating tool is made of tungsten carbide base cemented carbide, high speed tool steel, cermet or the like as the substrate, the balance between wear resistance and toughness is further optimized. However, when high-speed tool steel is used as the substrate, it is preferable to coat by physical vapor deposition in the range of 500 to 550 ° C. in consideration of its heat treatment characteristics. When the film is formed at such a relatively low temperature, the bias voltage to be applied and the reaction pressure at the time of film formation are appropriately optimized. As a film forming method, a film forming method in which a pulsed bias voltage can be applied and compressive stress is applied is preferable. An ion plating method such as an arc ion plating (hereinafter referred to as AIP) method or a sputtering method is preferred. If appropriate manufacturing conditions are applied, a composite apparatus in which each method is installed in one facility may be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by it. Unless otherwise stated, when (%) is described with respect to the composition, it means (atomic%).

As a test piece capable of measuring compressive stress, a hard coating according to the present invention was coated on the surface of a cemented carbide substrate in the shape of a turning insert, and the sample of Invention Example 1 was produced. The sample of Invention Example 1 uses an AIP apparatus, and the composition of only the metal component is atomic%, and the film thickness is 6 μm using a (TiAl) N film of Ti: 50% and Al: 50% as the first hard film. The film was formed as follows. Thereafter, a (TiB) N film having a composition of only metal components of Ti: 90% and B: 10% was formed as a second hard film with a film thickness of 6 μm so that the total film thickness was 12 μm. It is. The deposition temperature is 550 ° C., the reaction pressure is 3.5 Pa, and the (TiAl) N film, which is the first hard film, is formed by forming a 1 μm film with a bias voltage of DC 50V and then applying a pulsed bias voltage. . The pulse frequency was set to 10 kHz, and the positive bias voltage was set to 5V. After forming the (TiAl) N film, the (TiB) N film as the second hard film was also formed under substantially the same conditions as (TiAl) N, and the film was formed with only the bias voltage set to 150V.
Samples of Invention Examples 2 to 48 and Comparative Examples 49 to 65 in which the film thickness, composition, X-ray diffraction peak intensity, and compressive stress of the hard coating were changed using the film formation conditions of Invention Example 1 as a standard were also prepared. . The evaporation source is selected from various alloy targets according to Invention Examples 1 to 48 and Comparative Examples 49 to 55, and is used as a nitride, carbonitride, oxynitride, and oxycarbonitride. A hydrocarbon-based gas such as nitrogen, oxygen, and methane was used alone or mixed and introduced during film formation.

  For each sample prepared as described above, the hard coating composition is shown in Table 1, the hard coating formation conditions are shown in Table 2, and the measured values of compressive stress and the evaluation results of the coated insert cutting test are shown in Table 3. Each one is shown. As a result of observation of the film cross-section by TEM, all of the second hard films in Invention Examples 1 to 48 have a columnar structure, and the crystal grains of this columnar structure have a compositional difference in the B component with respect to the crystal grain growth direction. It was confirmed to have a structure.

  The produced turning insert was attached to a blade-type replaceable cutting tool, and a turning test was performed under the following conditions to confirm superiority or inferiority of wear resistance, fracture resistance, and adhesion. The insert used for the cutting evaluation uses a general-purpose CNMG120408 shape, using cemented carbide as a base, and HRA91 corresponding to M20 type in the JIS standard. In turning, a special insert with a chip breaker and a rake angle of 1 degree was used. In the evaluation method, the abrasion generated on the flank and rake face of the hard film-coated insert generated at a cutting distance of 5 m was observed with an optical microscope at a magnification of 50 times. Further, the cutting is continued, and when there is a defect including minute chipping of 10 μm or more, or when there is no defect, the time when the VBmax value of the flank wear width reaches 0.3 mm is defined as the tool life. Performance was evaluated by distance (m). The damage state of the cutting edge during cutting was appropriately observed.

(Cutting test conditions)
Cutting method: Continuous cutting in the longitudinal direction Work material shape: Round bar material with a diameter of 160 mm and a length of 600 mm Work material: S53C, HB260, tempered material Axial depth of cut: 2.0 mm
Cutting speed: 300 m / min Feed rate per rotation: 0.4 mm / rotation Cutting oil: None

Invention Examples 1 to 5 and Comparative Examples 49 and 50 were prepared in order to see the influence of the film thickness of the hard coating. The film thickness was adjusted by the coating time. The film thickness ratio of the first hard film and the second hard film was the same as 1: 1, and only the entire film thickness was changed. The compressive stress tended to increase as the thickness of the hard coating increased. Those having a total film thickness of 5 μm or more shown in Invention Examples 1 to 5 were excellent in wear resistance such as flank wear and crater wear. In any of the samples, there was no occurrence of welding of the workpiece component to the cutting edge in the initial 5 m of cutting. It is considered that having the second hard film specified in the present invention has a great effect on crater wear and welding resistance.
In Example 1 of the present invention, the total film thickness was 10 μm, the compressive stress value was 1.4 GPa, and the tool life was 18 m. As a result of confirming the damaged state of the cutting edge when the cutting distance is 5 m, the flank wear amount is 0.068 mm, which is superior to the thin film thickness examples 4 and 5 of the present invention and further compared to the comparative example 40. It was much better. When the damaged state of the cutting edge was confirmed during cutting, the hard coating was not dropped, peeled off, chipped, or the like in the vicinity of the cutting edge, and normal wear was exhibited. The example of the present invention in which film formation was performed by applying a pulsed bias voltage had a long tool life and excellent results.

The total film thickness of Comparative Example 49 was 40 μm, the compressive stress was 7.1 GPa, and the tool life was inferior to Invention Examples 1-5.
In Comparative Example 39, fine film breakage was observed at the edge of the blade edge before cutting. When the damage state of the edge part of the cutting edge during the cutting was confirmed, the film breakage expanded to a width of 9 μm, and the breakage part led to a defect. This is because the compressive stress is increased by increasing the total film thickness to 40 μm.
The total film thickness of Comparative Example 50 was 4 μm and had a low compressive stress of 1.3 GPa. However, the tool life was short due to inferior abrasive wear.

  Invention Examples 6 and 7 were prepared in order to observe the influence of the film thickness ratio of the first hard film and the second hard film. As shown in Inventive Example 6, the tool life was superior to Inventive Example 1 by increasing the thickness of the first hard coating. This was considered to be because progress of flank wear was suppressed. However, in Invention Examples 6 and 7, the second hard film was as thin as 1 μm and 3 μm, respectively, and crater wear occurred during cutting. The blade edge strength was lost due to the progress of crater wear, leading to defects. In order to confirm reproducibility, cutting evaluation was also performed for a film having a total film thickness of 12 μm and a second hard film coated to 0.3 μm, but the progress of flank wear was suppressed, but crater wear was the main component. Progressed to life.

Invention Examples 8 to 20 and Comparative Examples 51 and 52 were prepared in order to observe the influence of the composition of the first hard coating. It was produced by changing the composition of the target material for coating.
Invention Example 10, which has the best tool life, contained 10% tungsten (W), and was about 1.3 times better than Invention Example 1. When the cutting edge state was confirmed when the cutting distance was 5 m, chipping was not confirmed at the cutting edge part, and the flank wear was 0.029 mm. There was almost no welding of the workpiece at the cutting site, and the life was reached only by the progress of normal wear. It is considered that the reason why the flank wear is excellent is that the hardness is increased by containing W. The hardness of the first hard coating in Invention Example 1 was 28 GPa, and Invention Example 10 was 32 GPa. Furthermore, since the oxidation resistance has increased, it is considered that the progress of flank wear was suppressed. In particular, when the oxidation resistance is increased, damage at the tool boundary where the cutting heat is highest tends to be reduced. Further, the reason why welding did not occur is that boron (B) was contained in the second hard film of the outermost film and the lubrication characteristics were excellent.
Invention Example 12 contains 10% of niobium (Nb), and Invention Examples 13 and 14 contain chromium (Cr) and silicon (Si), so that the mechanical properties of the first hard coating are enhanced, and Invention Example 1 Excellent compared to
As shown in Invention Example 15, the tool life was excellent even when B was contained in the first hard coating. Welding was also suppressed at the portion of the first hard film exposed after the second hard film was worn. Even when B was contained in the first hard film, a remarkable effect was obtained with respect to welding and crater wear.
In Invention Examples 8 to 20, since the first hard film is a nitride of an element selected from Al, Group 4a, 5a, and 6a elements, Si, and B, heat resistance and hardness are remarkably improved.

In Comparative Example 51, the Al content of the first hard coating was 75%, and the welding phenomenon and the abrasive wear of the tool flank progressed from the beginning of cutting. In the observation of the structure of the first hard film cross section, the structure was refined. For this reason, compressive stress increases and adhesion deterioration can be considered. Further, the hardness of the first hard film was 20 GPa, and the decrease in hardness caused early progress of wear.
As a result of performing X-ray diffraction on Comparative Example 41, a hexagonal structure peak appeared in addition to the face-centered cubic structure peak. As a result of the investigation, it was confirmed that the peak was attributed to the AlN compound. Thereby, it is considered that the wear resistance is remarkably deteriorated. In Comparative Example 42, the same phenomenon was confirmed.

Invention Examples 21 to 24 and Comparative Examples 53 and 54 were prepared in order to see the influence of the composition of the second hard film. It was produced by changing the composition of the target material for coating. In inventive examples 21 and 22, the B content of the second hard coating was 1% and 25%, respectively. Inventive Example 23 had a Si content of 20%, and Inventive Example 24 contained B and Si. When the structures of the cross sections of these second hard coatings were observed, it was confirmed that all of them were columnar structures.
On the other hand, regarding the comparative example 53 in which the B content of the second hard film is 40% and the comparative example 54 in which the Si content is 30%, the cross-sectional structure of the second hard film is observed, and both are fine structures. It was confirmed. When the B and Si contents were increased, peeling of the hard coating and crater wear occurred from the beginning of cutting. The difference in the film structure resulted in superiority or inferior cutting performance. In particular, in Comparative Example 44 in which the Si content was 30%, many deposits were observed on the surface of the second hard film from the middle of cutting.

Invention Examples 25 and 26 and Comparative Examples 55 and 56 were prepared in order to observe the influence of oxygen and carbon contained in the first hard film. Oxygen and hydrocarbon gas were used as part of the reaction gas. For Invention Example 26 and Comparative Example 56 containing oxygen, nitrogen, argon (Ar), and oxygen were simultaneously introduced during film formation. In all cases, the total pressure was 3.5 Pa, and in the case of Invention Example 26, the gas was introduced at a gas flow rate ratio of 88% by volume of nitrogen, 10% by volume of argon, and 2% by volume of oxygen. In this case, when a large amount of oxygen was introduced, the arc discharge generated during film formation became unstable. Therefore, the inert gas Ar was introduced to adjust the total pressure. Although discharge is possible without using Ar gas, Ar gas was introduced for further stabilization. In Comparative Example 56, in order to increase the oxygen content, the amount of nitrogen was reduced and the amounts of Ar gas and oxygen gas were increased.
The tool life of Inventive Examples 25 and 26 was about 1.2 times better than Inventive Example 1 that did not contain oxygen and carbon elements. Moreover, the damage state of the blade edge at the time of the cutting distance of 5 m tended to be less welded and flank wear than the first example of the present invention. Furthermore, the occurrence of crater wear on the rake face was reduced. Since crater wear occurs due to a chemical reaction accompanying an increase in cutting temperature, the inclusion of oxygen and carbon increases the lubrication characteristics and reduces the friction coefficient. As a result, it is considered that the cutting temperature at which the chips scrape the rake face is suppressed, and wear is reduced.

  In Comparative Examples 55 and 56, since the x value and y value of the first hard film were 10% or more, peeling of the hard film and occurrence of crater wear were confirmed from the beginning of cutting, and the structure observation of the cross section of the first hard film was similarly performed. As a result, it was miniaturized. For Invention Example 1 containing no carbon, Invention Example 25 having a carbon content of 7%, and Comparative Example 55 having a carbon content of 15%, a sample of only the first hard film was prepared and the coefficient of friction was measured. The coefficient of friction was measured by a ball-on-disk method, and a SUJ2 φ6 mm ball was slid on a coated cemented carbide disc and measured without lubrication in the atmosphere. The wear resistance and welding resistance of the hard film at a measurement temperature of 600 ° C. were investigated. The friction coefficient of Invention Example 1 was 0.8, Invention Example 25 was 0.5, and Comparative Example 55 was 0.8. Even if the first hard coating contains a large amount of carbon, it is confirmed that damage such as flank wear, crater wear, and welding of the workpiece to the tool edge occurs from the beginning of cutting if the microstructure of the cross section of the coating becomes finer. It was. The same tendency was observed when oxygen was contained.

  Invention Examples 27 to 32 and Comparative Examples 57 and 58 were prepared in order to observe the influence of the reaction pressure on the composition during film formation. In particular, the influence of the e / f value and m / p value on the compressive stress was investigated. At this time, the reaction pressure was changed and set in the range of 0.2 Pa to 13.5 Pa. In the present invention examples 1 and 27 to 32 in which the film was formed at a reaction pressure of 2.2 to 9.1 Pa, the reaction pressure at the time of forming the first hard film was higher than that of the first example of the present invention. Excellent tool life. Inventive Example 29, which is also on the low pressure side as compared with Inventive Example 1, has a far superior tool life as compared with Comparative Examples 57 and 58, but extremely small chipping occurred at the beginning of cutting. It was. In particular, Invention Example 27 having an e / f value of 1.16 was the most excellent, and unstable elements such as chipping of the first hard coating did not occur. In Comparative Example 57 in which the film was formed at the lowest reaction pressure of 1.6 Pa, the compressive stress was 6.9 GPa, the e / f value was 0.82, and the tool life was 8 m. This was a short life of about 60% compared to Example 1 of the present invention. The lower the nitrogen pressure, the greater the compressive stress and the lower the e / f value. This reason is considered to be because the compressive stress of the first hard coating is high. When the compressive stress exceeded 6.0 GPa, it was confirmed that the first hard coating was broken at the edge of the blade edge in the damage state of the insert blade edge during cutting. In order to confirm reproducibility, as a result of performing cutting evaluation of several degrees using a new corner of the insert of Comparative Example 57, the tool life varied from 2 m to 0.2 m and was not stable.

  When the reaction pressure of Comparative Example 58 was 13.5 Pa, the m / p value was 1.28, the compressive stress at that time exceeded 7 GPa, and film peeling occurred at the beginning of cutting, leading to early chipping. Since the damage state of the cutting edge at the cutting distance of 5 m could not be observed, the damage at the initial cutting distance of 1 m was confirmed using a new corner, and as a result, the film from the substrate and the first hard coating interface at the edge of the cutting edge A large amount of welding occurred at the site where peeling and the first hard coating were removed. In addition, large wear on the flank and crater wear occurred. This was thought to be due to a decrease in the hardness of the first hard coating. The e / f value is 1.32 and the m / p value is 1.28. Although the cross-sectional structure of the first hard film has a columnar structure, many defects occur in the first and second hard films, and the adhesion Inferior in wear and wear resistance. The reason for this is considered to be that the kinetic energy when ions are incident on the substrate is lowered by performing the reaction pressure at 13.5 Pa.

  Invention Examples 33 to 40 and Comparative Examples 59 and 60 were prepared in order to observe the influence of the Is / Ir value. At the time of film formation, the pulse frequency of the pulse bias was kept constant at 10 kHz, and the bias voltage value was changed and set in the range of 20 to 300V. In Invention Example 1 and Invention Examples 33 to 40, the Is / Ir value was within the specified range of the present invention, the compressive stress was 4 GPa or less, and the tool life was excellent. Further, when the bias voltage was changed, the Is / Ir value was changed, and the compressive stress was changed accordingly. In Comparative Examples 59 and 60, the compressive stress exceeded 8 GPa, and peeling of the hard film was observed from the beginning of cutting. When the compressive stress was increased, the tool life was inferior.

  Invention Examples 41 to 46 and Comparative Examples 61 to 63 were prepared in order to see the effect of the It / Ir value of the first hard coating on the compressive stress. At this time, the positive bias value of the pulse bias voltage was changed from 5 to 40V. When the positive bias voltage increases, the orientation strength toward the (200) plane tends to be relatively strong, and the Is / Ir values of Invention Examples 1, 41 to 46 and Comparative Examples 61 to 63 are 2.44. It changed to ˜4.46. In Invention Example 1 and Invention Examples 34 to 36, the It / Ir value was within the specified range of the present invention, the compressive stress was relatively low, and a satisfactory tool life was obtained. On the other hand, in Comparative Examples 61 to 63, the positive bias voltage exceeded 20 V, the It / Ir value of the first hard coating was less than 0.6, and the first hard coating was peeled off when the blade edge was observed at a cutting distance of 5 m. Many were observed. Since the compressive stress increased and exceeded 6 GPa, not only peeling from the interface between the substrate and the first hard coating but also many shell-like fractures were observed, which resulted in a decrease in tool life. In order to improve the adhesion at the interface between the first hard film and the second hard film, the positive bias voltage value in the pulse bias voltage is controlled to be low, and the orientation strength of the (111) plane of the first hard film is lowered. This is very important. This is because application of a bias voltage having only a negative value is insufficient for suppressing defects caused by micro arcing during film formation.

Invention Examples 47 and 48 and Comparative Examples 64 and 65 were prepared in order to observe the influence of the (200) plane and (111) plane spacing on the X-ray diffraction of the first hard coating and the second hard coating, respectively. . The surface spacing was adjusted by changing the pulse frequency of the pulse bias voltage in the range of 1 to 40 kHz.
Examples 47 and 48 of the present invention are cases where the pulse frequency is 30 kHz and 2 kHz, respectively, but the d2 / d1 value is 1.01 to 1.02, and the compressive stress of the entire hard coating is reduced, and the first hard coating is reduced. And excellent adhesion of the second hard film, and a satisfactory tool life was obtained.
On the other hand, in Comparative Example 64 in which film formation was performed at a pulse frequency of 1 kHz, the d2 / d1 value was 1.07, and the adhesion deteriorated due to the gap between the first hard film and the second hard film. In Comparative Example 65, more peeling was observed at the interface between the first hard film and the second hard film than at the initial stage of cutting than between the base and the hard film. This was the cause of the short tool life. The reason for this is that since the film was formed at 40 kHz, the d2 / d1 value was 0.99, the compressive stress of the entire hard film increased to 6.9 GPa, and in addition to the adhesion to the substrate, the first hard film and the first hard film This is because the adhesiveness deteriorated due to misfit of the spacing between the two hard coatings.
It was also confirmed that the It / Ir value of the first hard coating also changed with the change of the pulse frequency. The relationship between the pulse frequency and the compressive stress is considered to be correlated, and the compressive stress tends to increase as the pulse frequency increases. This is considered to be due to the fact that the DC bias voltage is applied as the pulse frequency increases.

  The hard film-coated tool of the present invention can be applied to, for example, general tools for metal processing that require wear resistance.

Claims (4)

In a hard film coating tool in which a hard film having a compressive stress is coated on a substrate with a thickness of 5 to 30 μm, the hard film is coated with the first hard film and the second hard film from the surface of the substrate. The outer film is coated with the second hard film,
The composition of the first hard coating is (Al _a Me _100-a ) _e N _f (where a is atomic%, e and f represent atomic ratios, respectively 35 ≦ a ≦ 65, and 0.85) ≦ e / f ≦ 1.25, Al is aluminum, Me is at least one element selected from groups 4a, 5a, and 6a, Si and B, and N is nitrogen. And
The composition of the second hard coating is (Ti _100-h B _h ) _m N _p (where h is atomic%, m and p represent atomic ratios, respectively, 0 <h ≦ 30, and 0.90) ≦ m / p ≦ 1.15, Ti is titanium, B is boron, and N is nitrogen.)
The crystal structures of the first hard film and the second hard film are face-centered cubic structures, respectively.
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, 1.5 ≦ Is in the X-ray diffraction of the first hard film. /Ir≦15.0 and 0.6 ≦ It / Ir ≦ 1.5, and in the X-ray diffraction of the second hard film, 0.2 ≦ Is / Ir ≦ 1.0 and 0.6 ≦ It /Is≦1.5,
In the X-ray diffraction of the first hard coating and the second hard coating, the surface spacing (nm) of the (200) plane of the first hard coating is d1, and the (111) plane spacing of the second hard coating ( nm) is d2, and 1.00 ≦ d2 / d1 ≦ 1.03,
The hard film-coated tool, wherein the second hard film has a columnar structure, and the crystal grains of the columnar structure have a composition modulation structure having a composition difference in the B component.   2. The hard film-coated tool according to claim 1, wherein a part of nitrogen in the first hard film is replaced with carbon and / or oxygen, the whole nonmetallic component is 100 atomic%, and the carbon content is atomic%. Where x is the oxygen content and y is the oxygen content, 0 <x ≦ 10, 0 <y ≦ 10, 0 <x + y ≦ 10, and the nitrogen content is (100−xy), Hard film coated tool.   The hard film-coated tool according to claim 1 or 2, wherein a part of the titanium in the second hard film is replaced with silicon, the entire metal component is 100 atomic%, and the silicon content is atomic%. A hard film-coated tool, wherein 0 <k ≦ 20 and the content of titanium is (100−h−k), where k is k.   4. The hard film-coated tool according to claim 1, wherein the hard film having a compressive stress has a total film thickness of 10 to 30 [mu] m.