JP2005126736A - Hard film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard film and a hard film-coated tool excellent in high temperature oxidation resistance and extremely excellent in the adhesion with a base body in spite of having the high hardness. <P>SOLUTION: The hard film coated with an arc-discharge ion-plating method is composed of at least one layer, represented by (Al<SB>x</SB>Cr<SB>1-x-y</SB>Si<SB>y</SB>)(N<SB>1-α-β-γ</SB>B<SB>α</SB>C<SB>β</SB>O<SB>γ</SB>), wherein x, y, α, β and γ are respectively atomic ratio meeting 0.45<x<0.85, 0<y<0.35, 0≤α<0.15, 0≤β<0.65, 0.003<γ<0.2 and 0<α+β+γ<1.0. Further, this hard film has a rock salt structural type crystal structure in an X-ray diffraction measurement and a half-width of 2θ at a diffraction peak corresponding to a (111) face or a (200) face, is 0.5-2.0° and oxygen in this hard film exists more in the crystal grain boundaries than the inner part of the crystal grains. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hard coating that covers the surface of a cutting tool, a hard coating that covers the surface of a wear-resistant member that requires high hardness such as a die, a bearing, a die, or a roll, or a heat-resistant member such as an internal combustion engine component. The present invention relates to a hard film that covers the surface.

  The techniques shown in Patent Documents 1 to 4 are disclosed as AlCr-based coatings as hard coating materials having excellent high-temperature oxidation resistance. Patent Document 1 discloses an example of an amorphous film having high hardness in an AlCr hard film selected from AlCr and one of C, N, and O as a metal component. However, the hardness of this amorphous film is at most about 21 GPa in Knoop hardness, so that it cannot be expected to have a wear resistance effect, and the adhesion is not sufficient. The hard coatings disclosed in Patent Document 2 and Patent Document 3 are nitrides of AlCr and have high-temperature oxidation resistance of about 1000 ° C., but the oxidation resistance characteristics of 1000 ° C. or higher have been studied. In addition, the hardness is about 21 GPa in terms of Vickers hardness, and the improvement for increasing the hardness is not sufficient and the wear resistance is poor. Patent Document 4 proposes a wear-resistant film-coated tool in which a TiSi-based film and two or more nitride, carbonitride, nitride oxide, and boron nitride layers mainly composed of Cr and Al are laminated. However, there is a problem in adhesion.

Japanese Patent No. 3027502 Japanese Patent No. 3039381 Japanese Patent Laid-Open No. 2002-160129 Japanese Patent Laid-Open No. 2002-331408

  An object of the present invention is to provide a hard film and a hard film-coated tool that are excellent in high-temperature oxidation resistance and have high hardness and extremely excellent adhesion to a substrate.

The present invention is a hard film coated by an arc discharge ion plating method, and the hard film is (Al _x Cr _1-xy Si _y ) (N _1-α-β-γ B _α C _β O _γ ) where x, y, α, β, and γ represent atomic ratios, respectively, 0.45 <x <0.85, 0 ≦ y <0.35, 0.50 ≦ x + y <1.0, 0 ≦ It consists of at least one layer represented by α <0.15, 0 ≦ β <0.65, 0.003 <γ <0.2, 0 <α + β + γ <1.0. It has a crystal structure, the half width of 2θ of the diffraction peak of either the (111) plane or the (200) plane is 0.5 degree or more and 2.0 degree or less, and oxygen in the hard film is It is a hard film characterized by being present more at the crystal grain interface than inside the crystal grain. By adopting the above configuration, the high temperature oxidation resistance is greatly improved, and at the same time, the substrate adhesion is excellent and the (AlCr) N-based film can be remarkably increased in hardness, resulting in excellent wear resistance. The hard film of the present invention to be exhibited was completed.

  The hard coating of the present invention has a binding energy of at least Al, Cr and / or Si and oxygen in the range of 525 eV to 535 eV in X-ray photoelectron spectroscopy, and a depth within 500 nm from the outermost surface in the film thickness direction. The oxygen concentration is maximum in the region. Further, the hard coating of the present invention has a rock salt structure type (111) plane measured by X-ray diffraction with a diffraction intensity of I (111) and a (200) plane of I (200). 3 <I (200) / I (111) <12, and the elastic recovery rate E obtained by hardness measurement by nanoindentation is 28% ≦ E ≦ 40%.

  The hard film of the present invention contains oxygen, and by controlling the presence of the oxygen, the hard film and the hard film coating have excellent high-temperature oxidation resistance, high hardness, and extremely excellent adhesion to the substrate. The tool could be provided. By covering the tool with the hard coating of the present invention, it is possible to greatly improve the wear resistance, and it has become possible to greatly reduce the manufacturing cost in various industrial fields.

  When the compressive stress remaining in the hard coating increases, the coating can be made harder, while the adhesion to the substrate tends to deteriorate. Therefore, in order to obtain a high-hardness film having excellent adhesion to the substrate, it is necessary to reduce the compressive stress remaining in the film. Here, there is a technical contradiction regarding compatibility between high hardness and adhesiveness, and the conventional film has been increased in hardness while sacrificing a certain degree of adhesiveness with the substrate. The present invention, as a result of intensive studies on the effect of high hardness on the adhesion to the substrate, while using an AlCr-based film and excellent in high-temperature oxidation resistance, results in the oxygen being crystal particles in an AlCr-based film containing oxygen. By controlling the crystal grain interface to be larger than the inside, the residual compressive stress can be remarkably reduced while maintaining high hardness. At the same time, regarding the high-temperature oxidation resistance, the fact that oxygen exists at a high concentration at the crystal grain interface can suppress the grain boundary diffusion of oxygen from the outside and find out the fact that it can be greatly improved. Completed.

The hard film of the present invention is particularly excellent in adhesion to the substrate by coating by the arc ion plating method, and a hard film having a dense and high hardness can be obtained. The composition of the metal element constituting the hard coating of the present invention is such that (Al _x Cr _1-xy Si _y ), x is 0.45 <x <0.85, 0 ≦ y <0.35, 0. It is necessary to satisfy 50 ≦ x + y <1.0. When the value of x is 0.45 or less, the effect of improving the film hardness and the high temperature oxidation resistance is not sufficient, and when the value of x is 0.85 or more and the value of y is 0.35 or more, the residual compressive stress is excessive. And peeling occurs after coating. Furthermore, a hexagonal crystal structure is confirmed, and the strength sharply decreases. The composition of the non-metallic component constituting the hard coating of the present invention is (N _1-α-β-γ B _α C _β O _γ ) 0 ≦ α <0.15, 0 ≦ β <0.65, 0. It is necessary to satisfy 003 <γ <0.2 and 0 <α + β + γ <1.0. Addition of boron has an effect of reducing the welding resistance to the workpiece and the friction coefficient in a high temperature environment. When α was 0.15 or more, embrittlement of the film was confirmed, and the adhesion decreased. A preferable upper limit value of α is 0.08. The addition of carbon increases the hardness of the hard coating, is effective in reducing the coefficient of friction at room temperature, and an effect of improving wear resistance was observed. When β was 0.65 or more, embrittlement of the film was confirmed. A preferable upper limit of β is 0.35. γ needs to be larger than 0.003 and smaller than 0.2. When γ is 0.2 or more, the film hardness is remarkably lowered and the wear resistance is poor. Moreover, the effect of this invention is not acquired as it is 0.003 or less. A preferable value of γ is 0.005 or more and 0.15 or less. The ratio of N, B, C, O of nonmetallic elements to Al, Cr, Si of metallic elements is stoichiometrically more (N, B, C, O) / (Al, Cr, Si)> 1. preferable. The hard coating of the present invention has a rock salt structure type crystal structure measured by X-ray diffraction, and the 2θ half-value width of the diffraction peak of either the (111) plane or the (200) plane is 0. It is 5 degrees or more and 2.0 degrees or less. When the half-value width of 2θ of the diffraction peak on any surface is 0.5 ° or more and 2.0 ° or less, the hardness of the film is particularly high and the wear resistance is excellent. It is extremely effective that the oxygen present in the hard coating of the present invention is present more at the crystal grain interface than inside the crystal grain. In this case, remarkable improvement is made with respect to adhesion to the substrate or breakage and peeling from the inside of the film while being particularly high in hardness. That is, the action of the present invention has the effect of reducing the residual compressive stress of the entire film and improving the peel resistance. By adopting the above configuration, it is possible to obtain a film having high hardness and excellent adhesion to the substrate, and at the same time, with respect to high temperature oxidation resistance, oxygen entering from the outside through the crystal grain boundary This also has the effect of suppressing the diffusion of the metal and improves the high temperature oxidation resistance. In order to control the presence state of oxygen, which is a feature of the coating of the present invention, it is necessary to include optimum coating conditions and further to contain oxygen to a certain level or more in the hard coating.

The hard coating of the present invention has a binding energy of at least Al, Cr and / or Si and oxygen in the range of 525 eV to 535 eV in X-ray photoelectron spectroscopy. In this case, in particular, the film is densified, and the film has high hardness and excellent peel resistance. When the oxygen concentration becomes maximum in the depth region within 500 nm in the film thickness direction from the outermost surface of the hard coating of the present invention, the oxygen diffusion suppression effect is excellent and the high-temperature oxidation resistance is remarkably improved. It is also effective for reducing friction. When the oxygen maximum concentration layer is provided at a position exceeding 500 nm, the wear resistance is lowered. When the value of I (200) / I (111) measured by X-ray diffraction of the hard coating of the present invention is 0.3 or less, the crystallinity of the coating is poor, the characteristics become unstable, and abnormal wear is induced. On the other hand, when the value of I (200) / I (111) is 12 or more, the film hardness tends to decrease and the wear resistance deteriorates. The hard coating is required to determine the contact depth and the maximum displacement at the maximum load by the hardness measurement method using nanoindentation (WC Oliver, GM Pharr: J. Mater. Res. Vol.7, No.6, June 1992, 1564). -1583). Using this number,
E = 100-{(contact depth) / (maximum displacement at maximum load)}
When the elastic recovery rate E is defined by the following formula, the hard film of the present invention satisfies 28% ≦ E ≦ 40%. By being in this range, the balance between wear resistance and adhesion is optimal. A more preferable value of E is 30% to 35%. These can be optimized by the coating conditions.

  Immediately above the coating of the present invention, an element selected from at least one or more of Ti, Cr, Al, and Si, and one or two of N, C, O, and B as non-metallic elements When coated with at least one of a hard film composed of the elements selected from the above, or a hard carbon film or boron nitride, it is particularly excellent in adhesion to the film of the present invention and significantly complements the wear resistance. Is possible. When the hard coating of the present invention is coated on one type selected from the group consisting of drills, taps, reamers, end mills, gear cutting tools, broaches, interchangeable inserts and dies, the effect of the present coating is remarkable. In particular, a hard film coated tool having a great effect of improving wear resistance can be obtained. When the hard coating of the present invention is coated on a high-speed steel roughing end mill, the effect of improving adhesiveness, peel resistance, film hardness, etc., is significantly improved, and the wear resistance is greatly improved. An excellent hard film coated tool can be obtained. For the tool coated with the hard coating of the present invention, by smoothing the convex portion of the coating on the outermost surface by mechanical treatment, it is effective for chip dischargeability and chipping suppression of cutting edges in cutting, It is possible to improve the cutting life. Hereinafter, based on an Example, this invention is demonstrated concretely.

(Example 1)
An arc discharge ion plating apparatus was used for coating the hard coating of the present invention. The configuration includes a decompression vessel, an arc discharge evaporation source insulated from the decompression vessel, and a substrate holder. A target that is a metal component of the hard coating is installed, and a predetermined current is supplied to the arc discharge evaporation source to perform arc discharge on the target, the metal target component is evaporated and ionized, and between the vacuum vessel and the substrate holder. The substrate was coated with a negative bias voltage applied to the substrate. The substrate was degreased and cleaned and placed in a vacuum container. The substrate temperature was heated to 500 ° C. by a heating heater installed in the decompression vessel, and the substrate was heated and degassed by holding it for 30 minutes. Ar was introduced into the vacuum vessel, Ar element was ionized with a hot filament, and the substrate was cleaned with a bias voltage applied to the substrate. For the addition of carbon, oxygen, and boron into the hard coating, the reaction gases N ₂ gas, CH ₄ gas, C ₂ H ₂ gas, Ar gas, O ₂ gas, CO gas, and B ₃ N ₃ H ₆ gas are used. The gas from which one or more of the desired films can be obtained or a combination thereof was selected and introduced into the vacuum vessel. The method of adding oxygen into the hard coating can be performed by using an oxygen-containing gas, but can also be performed by using a metal target containing oxygen. As the metal target, various alloy targets prepared by a powder method were used. An alloy target of Al0.7Cr0.3 having an oxygen content of 3200 ppm in the metal target was installed, N ₂ gas was introduced as a reaction gas into the vacuum vessel, and the total pressure was 7.5 Pa. As the bias voltage, a negative bias voltage of −120 V, a positive bias voltage of +10 V, a frequency of 20 kHz, an amplitude of 80% on the negative side, and a pulse bias voltage of 20% on the positive side are used to start arc discharge, A coating treatment was performed. As the substrate, a test piece made of ultrafine particle cemented carbide having a Co content of 7% by weight and having a mirror-finished SNMN432 shape was used. The coating temperature was 450 ° C. and the film thickness was about 3.5 μm. The film obtained at this time was subjected to composition analysis using an electron beam probe microanalyzer. The analysis conditions were for an area of 50 μmφ, the acceleration voltage was 15 kV, the sample current of the metal component was 0.5 μA, and the sample current of the non-metal component was 0.1 μA. As a result of the analysis, as shown in Table 1, the composition of the hard film of Example 1 of the present invention was (Al _0.65 Cr _0.35 ) (N _0.96 O _0.03 C _0.01 ). The film forming conditions of the comparative example and the conventional example are the same as those of the example of the present invention unless otherwise specified except that the bias voltage application method is a constant negative bias voltage application.

  Using the test piece having the shape of SNMN432 mirror-finished to confirm the presence of oxygen in the obtained hard film, the JEM-2010F type field emission transmission electron microscope manufactured by JEOL Ltd. was used to measure the structure of the film cross section at high magnification. Observed at. As the observation condition, the acceleration voltage was set to 200 kV. Further, the oxygen content in the crystal grains and the oxygen content in the crystal grain boundaries were analyzed by an electron beam energy loss spectrometer of MODEL 766 manufactured by Gatan. In the electron beam energy loss spectroscopy, the analysis region was set to 1 nmφ. FIG. 1 shows the result of observing the structure of the film cross section of Example 1 of the present invention using a field emission transmission electron microscope. From FIG. 1, the crystal grains 1 and 2 shown in the region 1 and the region 2 are recognized, and the crystal grain boundaries are also clearly recognized. FIG. 2 shows the result of analyzing the 1 nmφ region of the crystal grain 2 in FIG. 1 by electron beam energy loss spectroscopy. FIG. 3 shows the result of analyzing the 1 nmφ region of the arrow portion, which is the grain boundary between the crystal grain 1 and the crystal grain 2 in FIG. 1, by electron beam energy loss spectroscopy. From FIG. 3, the presence of oxygen was clearly confirmed at the crystal grain boundary. 2 and 3, it is clear that oxygen in the hard film is contained more at the crystal grain interface at the arrow portion than inside the crystal grain corresponding to the periphery of the crystal grain 2 in FIG. In order to control the presence state of oxygen in the hard film containing oxygen so as to be larger at the crystal grain interface than inside the crystal grain, it is necessary to optimize the coating conditions. It is also effective to use a metal target containing oxygen. The reaction gas pressure for the coating conditions is preferably 2 Pa to 15 Pa. When using a metal target containing oxygen, the oxygen content in the metal target is preferably 2000 ppm or more. For example, when the oxygen content in the metal target was 1800 ppm, no difference in oxygen concentration was observed between the crystal grains and the grain interface. The oxygen intensity ratio P between the crystal grains and the grain interface is a value obtained by dividing the oxygen intensity at the crystal grain interface by the oxygen intensity inside the crystal grain in the electron beam energy loss spectroscopic analysis. Is greater than 1 and greater than or equal to 4.

In order to confirm the oxygen binding state of the hard film, X-ray photoelectron spectroscopic analysis was performed using a test piece coated with the film of Example 1 of the present invention using a PHI 1600S type X-ray photoelectron spectrometer. The X-ray source was set to 400 W using MgKα, and the analysis region was inside a circle of 0.4 mmφ. The surface of the sample before analysis was thoroughly degreased and cleaned. The spectrum was measured in an X-ray photoelectron spectroscopy analyzer held in a vacuum. An Ar ion gun was placed at a position inclined by 50 degrees with respect to the sample surface, a 10 mm ² region was sputtered with Ar ions for 24 minutes, and the spectrum of the sample outermost surface was measured. The sample surface was etched with Ar ions at intervals of 24 minutes, and the spectrum was measured. This cycle was repeated and continued until the total time was 120 minutes. The photoelectron detector was arranged at a position inclined by 35 degrees with respect to the sample surface, and the X-ray generator was arranged so that X-rays were incident from a position of 90 degrees with respect to the sample surface. The etching rate by Ar ion etching was 1.5 nm / min in terms of SiO ₂ . FIG. 4 shows the spectrum after performing an Ar ion etch for 120 minutes. From FIG. 4, it was confirmed that oxygen was present in the film of Example 1 of the present invention. FIG. 5 shows the result of elemental analysis in the film thickness direction in X-ray photoelectron spectroscopy. From FIG. 5, it was confirmed that about 6% of oxygen was present in the film of Example 1 of the present invention in terms of atomic percentage of only nonmetallic elements. FIG. 6 shows the spectrum corresponding to O1S measured at intervals of 24 minutes, displayed by time. The rear side of FIG. 6 is the spectrum of the outermost surface of the sample, and the spectrum at the analysis position deeper in the film thickness direction is shown on the front side. From FIG. 6, it was confirmed that in Example 1 of the present invention, the binding energy of metal and oxygen was in the range of 525 eV to 535 eV, and these were binding energy of Al, Cr and / or Si and oxygen. In addition, on the sample surface side, the bond between carbon and oxygen is mainly, and the bond between metal and oxygen is mainly inside the film. Table 1 shows the presence / absence of the binding energy between the metal and oxygen and the confirmed bonding state in the range of 525 eV to 535 eV of each coating.

(Example 2)
A microindentation hardness tester was used to measure the indentation hardness by the nanoindentation method. As the indenter, a triangular pyramid indenter made of diamond with an angle of 115 ° was used. The maximum load was 49 mN, the load load step was 4.9 mN / sec, and the holding time at the maximum load was 1 second. Using a mirror-finished test piece, the test piece was tilted by 5 degrees, and 10 points were measured at positions where the film thickness was 2 to 3 μm. Table 1 shows the average value when the hardness of each film was measured. The elastic recovery rate E was calculated from the load displacement curve obtained in the indentation hardness measurement. Table 1 shows the results of measuring E of each film.

(Example 3)
As an evaluation of the high temperature oxidation resistance of the hard coating, each coating shown in Table 1 was coated on the test piece, held in an oxidizing atmosphere of 1100 ° C. in the atmosphere for 9 hours, and the thickness of the oxide layer was measured. The thicker the oxide layer, the stronger the inward diffusion of oxygen, indicating poorer oxidation resistance. The thickness of the oxide layer of each film is also shown in Table 1.

Example 4
In order to evaluate the adhesion of the hard coating, each test piece shown in Table 1 was coated on the test piece, and the hardness was measured from the surface of the hard coating with a Rockwell hardness meter at 1470 N. evaluated. A film that peels off means poor adhesion. The presence or absence of peeling of each film is also shown in Table 1.

(Example 5)
X-ray diffraction was performed to evaluate the crystallinity of the hard coating. The X-ray incident angle was set to 5 degrees. From the obtained profile, I (200) of each film when the strength of the strongest surface index and the (111) plane of the rock salt structure type crystal structure is I (111) and the strength of the (200) plane is I (200). ) / I (111) and the value obtained by measuring the 2θ half width of the strongest surface index of either the (111) plane or the 200) plane are shown in Table 1.

  From Table 1, it was confirmed that in each of Invention Examples 1 to 12, the oxygen concentration at the crystal grain interface was higher than the oxygen content inside the crystal grain. As a result, the inventive examples were higher in hardness than Comparative Examples 13 to 15 and Conventional Examples 16 and 17, and in addition, no peeling was observed in the adhesion evaluation, indicating good adhesion. Inventive Example 1 to Inventive Example 12 were within the numerical specification of the present invention with respect to the 2θ half width of the plane index indicating the strongest intensity in X-ray diffraction, while Comparative Example 14 was 0. 3 degrees and Comparative Example 15 were 2.1 degrees, which was outside the numerical values of the present invention. For this reason, Comparative Examples 14 and 15 showed low hardness, and the effect of improving adhesion was not confirmed. Also in the evaluation regarding the high temperature oxidation resistance, it was confirmed that Examples 1 to 12 of the present invention were excellent in that the progress of oxidation was slow. Invention Example 8 shows a case where oxygen bonds are not clearly confirmed in the range of 525 eV to 535 eV, but the hardness is higher when oxygen bonds are observed in the range of 525 eV to 535 eV. Invention Example 9 shows a case where the numerical value of I (200) / I (111) by X-ray diffraction is 15, but 0.3 <I (200) / I (111) which is the specified range of the present invention. <12 showed higher hardness. Example 10 of the present invention shows a case where the value of E, which is the elastic recovery rate in the hardness measurement method by nanoindentation, is 27, but the example of 28 ≦ E ≦ 40, which is the specified range of the present invention, is more Since it has high hardness and satisfactory adhesion, it indicates that the characteristics are excellent. Invention Example 11 is an example of the invention coated so that the oxygen concentration is maximized within 500 nm from the surface of the film, which resulted in excellent high-temperature oxidation resistance. Example 12 of the present invention shows an example of a mixed crystal that has a rock salt structure type crystal structure in X-ray diffraction, and a part of which is a hexagonal crystal considered to be AlN, but is composed only of a rock salt structure type. Showed higher hardness. Comparative Example 13 is an example where the reaction gas pressure during coating is 0.3 Pa. The concentration difference between the oxygen content inside the crystal grains in the hard coating and the oxygen content at the crystal grain interface was not confirmed, and no increase in hardness and improvement in adhesion were observed.

(Example 6)
In order to evaluate the wear resistance of the cutting tool, cutting was evaluated by coating a high-speed steel outer diameter 12 mm, four blades, and a luffing end mill. The evaluation was the cutting length until the average flank wear width reached 0.25 mm, or the cutting length when the tool was broken. Table 1 shows the cutting length of the tool coated with each coating. Cutting conditions are shown below.
(Cutting conditions)
Cutting method: rough side surface Work material: SCM440 (HRC31)
Cutting: radial cutting, Rd, 6 mm, axial cutting, Ad, 12 mm
Cutting speed: 70 m / min
Feed: 0.07mm / blade Cutting oil: None (dry type by air blow)

  As can be seen from Table 1, Examples 1 to 12 of the present invention have a longer cutting life and superior wear resistance than Comparative Examples 13 to 15 and Conventional Examples 16 and 17. Inventive Example 3 and Inventive Example 4 are examples of an AlCrSiNO film, and the cutting life was particularly long and the wear resistance was excellent. Furthermore, Example 7 of the present invention is an AlCrNOB coating, but by adding B, the wear was excellent. Example 8 of the present invention is a case where an oxygen bond is not clearly confirmed in the range of 525 eV to 535 eV, and when the oxygen bond is recognized in the other range of 525 eV to 535 eV, the hardness is higher and the cutting length is longer. Excellent wear resistance. Invention Example 9 is a case where the value of I (200) / I (111) is 15, and the cutting life is longer and the wear resistance is superior when the value is within the other specified range of the present invention. Invention Example 10 is a case where the E value is 27, and the cutting length is longer and the wear resistance is superior in the range specified in the present invention. Invention Example 11 is a case where the oxygen concentration was coated within 500 nm from the surface of the coating, and the cutting life was the longest. Invention Example 12 shows an example of a mixed crystal in which a hexagonal crystal considered to be AlN is confirmed in addition to a rock salt structure type crystal structure in X-ray diffraction. The configuration of the rock salt structure type alone has a longer cutting life and better wear resistance. Comparative Example 13 is a case where the reaction gas pressure at the time of coating is 0.3 Pa, and the difference in concentration of oxygen content between the inside of the crystal grain and the crystal grain interface was not confirmed, so that the hardness was increased and the adhesion was improved. Therefore, the wear resistance was not improved and the life was short. Comparative Example 14 and Comparative Example 15 are cases where the half width of 2θ is 0.3 degree and 2.1 degree, respectively, and there is no effect of improving hardness and adhesion, so the wear resistance is not improved and the life is short. Met.

(Example 7)
In order to further improve the cutting performance of the coating of the present invention, a cutting test was performed using a tool further coated with the coating on the coating of the present invention. The tool used was the same tool as in Example 6, coated with the coating of the present invention, and further coated with about 1 μm of the coating on top of it. Cutting conditions and evaluation criteria were the same as in Example 6. Table 2 shows the coating composition of each tool and the maximum tool life.

  Invention Example 18 to Invention Example 23 show examples in which the film shown in the upper layer column of Table 2 was coated on the film of Invention Example 5. It is clear that the cutting length is longer than the coating 5 of the present invention and the wear resistance is excellent. Invention Example 24 shows an example in which the film shown in the immediately upper layer column of Table 2 was coated directly on Invention Example 7. Invention Example 24 has a longer cutting life than the Invention Example 7 and is excellent in wear resistance. Invention Example 25 to Invention Example 31 show examples in which the film shown in the upper layer column of Table 2 is coated on the film 3 of the present invention. Inventive Example 25 has a longer cutting length and excellent wear resistance than Inventive Example 3. In Invention Example 32 to Invention Example 34, the convex portions on the surface of the immediately upper layer film of Invention Examples 26, 27, and 31 are smoothed by mechanical treatment. This treatment resulted in a tool life of up to 1.2 times. Comparative example 35 and comparative example 36 show examples in the case where a TiZrN film and a VZrN film are coated on the upper layer. The adhesion with the coating of the present invention was poor, and the wear resistance of the coating of the present invention could not be further improved. From these, the element selected from at least one or more of Ti, Cr, Al, and Si, and the nonmetallic element, one of N, C, O, and B, immediately above the coating of the present invention. Alternatively, it is preferable to cover at least one layer of a hard film composed of an element selected from two or more kinds, a hard carbon film, or boron nitride in order to extend the tool life.

FIG. 1 shows a cross-sectional observation result of the coating of the present invention using a field emission transmission electron microscope. FIG. 2 shows the result of analyzing the region of the crystal grain 2 in FIG. 1 by electron beam energy loss spectroscopy. FIG. 3 shows the result of analyzing the particle boundary indicated by the arrow in FIG. 1 by electron beam energy loss spectroscopy. FIG. 4 shows the spectrum results by X-ray photoelectron spectroscopy. FIG. 5 shows the results of elemental analysis in the film thickness direction by X-ray photoelectron spectroscopy. FIG. 6 shows the hourly display of the O1S spectral region by X-ray photoelectron spectroscopy.

Claims (6)

It is a hard film coated by an arc discharge ion plating method, and the hard film is (Al _x Cr _1-xy Si _y ) (N _1-α-β-γ B _α C _β O _γ ), x, y, α, β, and γ each represent an atomic ratio, and 0.45 <x <0.85, 0 ≦ y <0.35, 0.50 ≦ x + y <1.0, and 0 ≦ α <0. 15, 0 ≦ β <0.65, 0.003 <γ <0.2, 0 <α + β + γ <1.0, and has a rock salt structure type crystal structure in X-ray diffraction measurement. The half-width of 2θ of the diffraction peak of either the (111) plane or the (200) plane is 0.5 degrees or more and 2.0 degrees or less, and oxygen in the hard film is from inside the crystal grains. A hard film characterized by the presence of a large amount at the crystal grain interface. 2. The hard film according to claim 1, wherein the hard film has a binding energy of at least Al, Cr and / or Si and oxygen in the range of 525 eV to 535 eV in X-ray photoelectron spectroscopy. 3. The hard film according to claim 1, wherein the oxygen concentration is maximum in a depth region within 500 nm in the film thickness direction from the outermost surface of the hard film. The hard film according to any one of claims 1 to 3, wherein the diffraction intensity of the (111) plane of the rock salt structure type measured by X-ray diffraction of the hard film is the diffraction of the I (111) and (200) planes. A hard film characterized by 0.3 <I (200) / I (111) <12 when the strength is I (200). 5. The hard film according to claim 1, wherein the hard film has an elastic recovery rate E determined by hardness measurement by nanoindentation of 28% ≦ E ≦ 40%. 6. The hard film according to claim 1, wherein a convex portion on the surface of the hard film is smoothed by a mechanical treatment.