JP2008213059A - Hard coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart excellent performance of carbide, etc. by making a carbide phase exist in a nitride phase of a hard coating containing Si, and improving brittleness and lubricity of a nitride coating without sacrificing a characteristic having excellent wear resistance in high hardness. <P>SOLUTION: This hard coating has 2 to 50% of Si and 50 to 98% of a M component in atomic%. The M component has one kind or more selected among Ti, Cr, Zr, Nb, W, Mo and V. In the hard coating, the carbide phase exists in the nitride phase. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in the performance of a nitride film in which a carbide phase is present in the nitride phase.

  Hard coatings using nitrides and carbides are disclosed in Patent Documents 1 to 3.

JP 2004-34186 A JP 2000-308906 A JP 2001-293601 A

  The object of the present invention is to improve the brittleness and lubricity of the nitride film without sacrificing the characteristics of high hardness and excellent wear resistance by making the carbide phase present in the nitride phase of the hard film containing Si. To do.

  In the present invention, the hard coating is atomic%, Si is 2 to 50%, M component is 50 to 98%, and M component is selected from Ti, Cr, Zr, Nb, W, Mo, and V. The hard film has one or more types and is characterized in that a carbide phase is present in the nitride phase. By adopting the above configuration, the carbide phase is present in the nitride phase of the hard film containing Si, and the brittleness and lubrication of the nitride film are not sacrificed without sacrificing the characteristics of high hardness and excellent wear resistance. Can improve sex.

  The present invention improves the brittleness and lubricity of a nitride film without sacrificing the characteristics of high hardness and excellent wear resistance by having a carbide phase present in the nitride phase of a hard film containing Si. I was able to.

The present invention is a hard coating with improved brittleness and lubricity without sacrificing the high hardness and excellent wear resistance of the Si-containing coating. For example, investigations were made on hard coatings that can extend tool life. As a result of careful observation of the cutting phenomenon, the factors governing the tool life are microchipping of the hard coating due to the brittle properties of the Si-containing hard coating and the strong adhesion of the work material component to the Si-containing hard coating. It turned out to be an adhesion phenomenon. Thus, rather than improving the wear resistance by increasing the hardness of the Si-containing coating, a means for solving the adhesion phenomenon was examined. It was thought that the above-mentioned problems could be solved by relieving the residual compressive stress of the Si-containing hard film and simultaneously improving the lubricity.
The relaxation mechanism of the residual compressive stress in the hard coating of the present invention is obtained by the presence of a carbide phase in a nitride phase composed of one or more selected from Si and M components. Thereby, although the hardness tends to decrease somewhat, the residual compressive stress is greatly reduced, and the chipping resistance can be remarkably improved while the hardness is high. For example, in a cutting tool, the lubricity is affected by the affinity with iron-based work materials, adhesion resistance, and sliding characteristics. It is obtained by reducing the affinity with the iron-based work material and having a self-lubricating action. As the existence form of the nitride phase and the carbide phase, each phase exists in a granular form, and the carbide phase may exist at the grain boundary of the nitride phase.
The hard coating of the present invention has a low hardness and poor wear resistance when the Si content is atomic% and less than 2%. On the other hand, when it exceeds 50%, the volume ratio of amorphous increases, and the film hardness decreases remarkably. Accordingly, the Si content is 2 to 50%, more preferably 10 to 25%, from the balance of film hardness and lubricity. Further, the M component is 50 to 98%, but the M component needs to contain one or more selected from Ti, Cr, Zr, Nb, W, Mo, and V. When these are contained, the hardness of the Si-containing hard coating is increased and the wear resistance is excellent. In particular, when the metal component contains one or more selected from Ti and Cr in the range of 75 to 90%, the hardness is high and the lubricity is excellent. Further, when Zr, Nb, W, Mo, V is included, it is preferable to add at least one selected from Ti and Cr because the hardness and lubricity are improved. The addition amount is optimally 1 to 20%.
In the hard coating of the present invention, it is important that a carbide phase is present in the nitride phase. The nitride phase improves the hardness of the film and is effective for wear resistance. The presence of the carbide phase is effective for improving the lubricity. As a result, the contradictory properties of high hardness and lubricity can be improved at the same time, and the brittleness and lubrication properties of the Si-containing coating can be improved at the same time. In the present invention, improvement of lubricity is particularly important. The nitride film has a tendency that the lubrication characteristic decreases as the hardness of the film increases. This is considered to be due to a decrease in self-lubricating characteristics. However, according to the present invention, the presence of a carbide phase in the nitride phase of Si and M components can simultaneously improve the contradictory properties of high hardness and lubricity. This is because the presence of the carbide phase in the Si-containing nitride phase exhibits self-lubricating properties at the grain boundaries in addition to the refinement of Si-containing nitride particles. By doing so, high hardness and lubricity could be improved at the same time.

The method for coating the hard coating of the present invention is preferably a coating method by sputtering on the substrate. The sputtering method is difficult to separate the compound in the target into a metal component and a non-metal component, and is easily controlled so that these two or more compounds are stably present in the film. Therefore, in the hard coating of the present invention, most of the compounds in the target exist as nitrides and carbides even in the coating. Carbon is mostly present as a carbide, and is preferably a film in which slightly free carbon is present. If the power value applied to the sputtering evaporation source is too high, the compound in the target may dissociate into a metal component and a non-metallic component, and if it is too low, the metal in the target is preferentially sputtered and the compound is coated. May not be detected within. Therefore, the power value is preferably 2 to 6 kW per sputtering evaporation source. In order to satisfy the configuration of the present invention, it is effective to use a combined addition of Ar and Kr as a sputtering gas by appropriately selecting a bias voltage at the time of coating, a substrate temperature, and a method for introducing a reactive gas. By the sputtering method, it is possible to easily impart lubricity while increasing the hardness of the hard coating. Moreover, when the compound exists in the target, these compounds can be uniformly contained in the film, and it does not become a laminated film having a different composition, and even when a shear stress in a parallel direction acts on the film, it has high strength. Excellent wear resistance.
In order for the carbide phase to be present in the nitride phase, which is an important configuration of the present invention, it is effective to contain nitride and carbide in addition to the metal as a target. The target is preferably used by embedding or sticking a nitride, a carbide lump or the like on a metal target by a division method or an embedding method.
The coating method of the present invention can be used in combination with a plasma chemical vapor deposition method, an arc ion plating (hereinafter referred to as AIP) method, and a filter system AIP method in addition to the sputtering method. In the sputtering method, a DC power source, a high frequency power source, or a pulse power source can be used as a sputtering power source. As the bias power source, a DC power source, a high frequency power source, or a pulse power source can be used. The plasma chemical vapor deposition method is a method of adding a constituent element of a hard coating as a gas and ionizing it in plasma. In this method, a high frequency power source or a pulse power source is used as a bias power source as means for promoting ionization. preferable. By disposing the holocathode electrode in the vicinity of the substrate for ionizing the gas, ionization of the introduced gas is promoted, and the crystal grain size of the film can be controlled relatively easily. In the filter type AIP method, the angle formed between the surface of the metal target installed in the arc evaporation source and the surface of the substrate in the case of a flat substrate is preferably 40 ° or more and 90 ° or less. The distance induced by the magnetic field and the bias power source is preferably as long as possible. In addition, it is effective for reducing the macro particles to make the magnetic field strength as strong as possible, which is convenient for forming the hard coating of the present invention. However, in a single method based on the normal AIP method, the target constituent element component evaporates instantaneously and is coated on the substrate, so that it is difficult for two or more kinds of compounds to be present in the film. Therefore, it cannot necessarily be constituted so that two or more kinds of compounds exist in the film. This is considered because the compound added in the target is easily dissociated into a metal component and a non-metal component once. In order for these two or more compounds to be present in the film, a film formation method different from the conventional film formation method is required.

The hard coating of the present invention has a carbide phase in the nitride phase, X-ray photoelectron spectroscopic analysis of the coating cross section, and the abundance ratio (%) calculated from the area ratio by peak fitting is from 50 for the nitride phase. 99% and the carbide phase is preferably 1 to 50%. In this case, particularly excellent high hardness and lubricity can be obtained. If the nitride phase is less than 50% and the carbide phase exceeds 50%, the hardness tends to decrease and the wear resistance tends to decrease. At the same time, the adhesion strength also decreases. Even if the carbide phase is 1%, the effect of improving lubricity is exhibited.
The carbide phase is preferably a carbide selected from Si, Ti, Cr, Zr, Nb, W, V. This carbide phase provides a hard film with high hardness and excellent wear resistance and lubricity. In particular, when the carbide is Si carbide, nitride particles mainly composed of Si are refined, and a hard film having high hardness and excellent lubrication characteristics can be obtained. There are cases of having a crystal structure of these carbides and cases of having an amorphous structure.
The coated cutting tool coated with the hard coating of the present invention is preferable because the durability of the tool is remarkably improved. By coating the cutting tool with the hard coating of the present invention, the tool life is remarkably increased, which is preferable. Examples of the cutting tool include an end mill, a drill, a reamer, a tap, a broach, a hob, a cutter, a micro drill, a router, a milling insert, and a turning insert. The base material of the cutting tool is preferably a cemented carbide or cermet having a Co content of 3 to 12% by weight, high-speed steel, or a cubic boron nitride sintered body. The hard coating of the present invention has excellent adhesion strength when combined with these base materials, and is effective in extending the life of the cutting tool. When the Co content of the cemented carbide is less than 3% by weight, sudden chipping or chipping of the cutting edge may occur. On the other hand, when the Co content exceeds 12% by weight, the coating effect is small.

  The area ratio of the macro particles present on the surface of the hard coating of the present invention is preferably 5% or less. The presence of macro particles reduces adhesion resistance. Among physical vapor deposition methods, it is effective and effective for improving the adhesion resistance to reduce the abundance ratio of macro particles to 1% or less by sputtering. Moreover, the area ratio of the macroparticle which exists in the membrane | film | coat surface can be reduced by removing mechanically the macroparticle adhering to the membrane | film | coat surface after a coating process. Here, the macro particles are attached particles having a convex shape with respect to the surface of the coating and having a size of several hundred nm to several μm, and the core is mainly composed of a metal component. The area ratio of the macro particles is calculated by photographing the vicinity of the flank of the chisel edge of the ball end mill at a magnification of 3k to 10k with a scanning electron microscope, quantifying the area of the convex macro particles by image analysis processing, and calculating the area ratio. did. In order to further draw out the characteristics of the hard coating of the present invention, the main component is a nitride containing two or more metal components selected from Al, Cr, Ti, Si, Nb, and W between the base material and the hard coating. It is preferable to coat the intermediate layer. The intermediate layer has high adhesion strength with the hard film, and the peel resistance is improved. As a result, the wear resistance effect can be exhibited. The crystal structure of the intermediate layer is preferably a face-centered cubic structure, and is preferably strongly oriented in the (111) or (200) plane. More preferably, the intensity ratio I (200) / I (111) is 0.6 to 5. Suitable intermediate layer components are AlCr-based nitride, AlCrSi-based nitride, and AlCrNbSi-based nitride. When a certain amount or more of Al is added to the hard coating of the present invention, the abundance ratio of hexagonal crystals tends to increase, and as a result, the amount of Si added is limited. Therefore, when Al is included, 10% or less, or Al It is preferable not to contain. The crystal structure of the hard coating of the present invention is mainly a cubic crystal structure and may contain an amorphous phase. I (200) / I (111), which is the intensity ratio obtained by dividing the X-ray diffraction intensity of (200) by the X-ray diffraction intensity of (111) is 2 To 8 is optimal, and has high hardness and high toughness and excellent lubricity. The hard film of the present invention has a carbide phase in the nitride phase, but in addition, the atomic ratio of the non-metal component of the nitride is less than 50%, and from boron, carbon, oxygen, and sulfur. It may contain selected components. In particular, the inclusion of one or more selected from boron, carbon, oxygen, and sulfur is preferable from the balance of wear resistance and lubricity. The hard coating of the present invention preferably contains less than 5 atomic% of Ar and / or Kr. By containing Ar and / or Kr, the bombardment effect at the time of coating is improved, the coating surface becomes smoother, and the adhesion resistance can be further improved, which is preferable. The presence of Ar and / or Kr at the grain boundaries reduces the residual compressive stress and reduces chipping. When the content of Ar and / or Kr is more than 5 atomic%, the film hardness is significantly lowered and the wear resistance is lowered. Furthermore, it escapes out of the film in a high temperature environment, promotes oxygen diffusion, and decreases oxidation resistance. Ar and / or Kr has a preferable content of 0.01 to 0.8 atomic%. The presence and quantification of Ar and / or Kr can be analyzed by electron probe microanalyzer analysis and Auger electron spectroscopy analysis.

The qualitative analysis of the compound present in the hard coating of the present invention and the measurement of the abundance ratio can be performed by X-ray photoelectron spectroscopy. The abundance ratio of nitride and carbide was calculated from the area area ratio by Si2p peak fitting from a chart obtained by X-ray photoelectron spectroscopy. For the X-ray photoelectron spectroscopic analysis, an X-ray photoelectron spectroscopic analyzer (manufactured by PHI, Quantum 2000 type) was used. For example, the following measurement conditions are preferable. AlKα was used as the X-ray source, and the analysis area was analyzed inside a circle having a diameter of 0.1 mm. Before the analysis, the analysis area is sufficiently ultrasonically cleaned with acetone, and in addition, in order to remove contaminants attached to the surface of the coating in the analysis section, a wider area than the analysis area is etched using an Ar ion gun for 10 minutes. The spectrum in the analysis region was measured. At this time, the etching rate by Ar ion gun is 6.5 nm / min in terms of SiO 2, and peak separation is performed by the peak fitting method. The qualitative characteristics of each peak are the values described in Physical Electronics, Handbook of X-ray Photoelectron Spectroscopy. It is preferable to use it. The peak value of the compound may vary slightly depending on the state of chemical bonding in the film. For quantitative analysis of the composition of the entire film, an electron probe microanalyzer (JXA-8900R manufactured by JEOL Ltd., hereinafter referred to as EPMA) is used to measure an acceleration voltage of 15 kV, a sample current of 0.2 μA, and a counting time of 10 seconds. Was carried out five times, and the average value was taken.
The measurement of the film hardness in the hard film of the present invention used a nanoindentation apparatus. The coated specimen was tilted 5 degrees and mirror-polished to select a region where the film thickness reached a maximum of about 2 μm within the exposed surface of the hard film. Ten points were measured under the measurement conditions of an indentation load of 49 mN, a maximum load holding time of 1 second, and a removal speed after loading of 0.49 mN / second, and the average value was obtained. The film hardness in this measuring method is easily influenced by the fine shape of the indenter, the temperature and humidity at the time of measurement, and the surface state of the sample, and the obtained numerical values do not necessarily match the Vickers hardness. Therefore, single crystal Si was measured at the same time, and the film hardness of the single crystal Si at that time was 15 GPa. Relative comparison can be made based on this measurement result. The hardness of the hard coating of the present invention is preferably 35 to 65 GPa. If it is less than 35 GPa, the wear resistance tends to be reduced, and if it exceeds 65 GPa, the adhesion strength with the substrate tends to be poor. A more preferable film hardness is 40 to 65 GPa. Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to the following Example, It can change suitably by the field of use.

(Example 1)
The hard film of the present invention was coated by the following method. A 2-flute ball end mill made of ultrafine cemented carbide with a Co content of 8% by weight as a base material, and SNMN432 made of ultrafine cemented carbide with an Co content of 8% by weight for evaluating the characteristics of a hard coating. A test piece having a shape was prepared. Degreasing and cleaning were sufficiently performed, and a ball end mill and a test piece were placed on a jig in the container of the sputtering apparatus. The jig revolves at 1 revolution / minute. The substrate is heated and evacuated so that the temperature of the substrate becomes 500 ° C., and then Ar and Kr are introduced into the container and discharged between the cathode electrode and the anode electrode provided in the container. Ionization was performed. At the same time, a pulsed bias voltage was applied to the substrate. The pulsed bias voltage was set such that the negative bias voltage was 500 V and 90%, the positive bias voltage was 20 V and 10%, and the cycle was 20 kHz. The ionized Ar and Kr collide with the substrate, and the substrate is cleaned and activated. Thereafter, Ar, Kr, and N2 were introduced into the container at a flow rate ratio of 3: 2: 1, and the overall pressure was set to 0.1 Pa and the negative bias voltage was set to 100V. Four sputtering evaporation sources, number 1 to number 4, are arranged in the container and each has a non-equilibrium magnetic field. The hard coating of the present invention was coated with a film thickness of 2 μm by supplying 4 kW of power to the two sputtering evaporation sources numbered 3 and 4 respectively. Thereafter, the substrate was removed from the vacuum container at a substrate temperature of 200 ° C. or lower. The target used is a rectangle having a length of 500 mm and a width of 100 mm, and has fixing holes at the four corners and the center, and is fixed to the sputtering evaporation source. The area of the discharge region is approximately 25000 mm 2, but no sputter discharge occurs at the four corners and the center. Therefore, the discharge region on the target surface was divided into three regions to four regions, and the material to be used by embedding in each region and the area ratio were determined.
In Examples 1 to 17, 21, 24, 27 to 34, the area ratio of the region 1 to the region 3 was 90%, the region 2 was 7%, and the region 3 was 3%. The area ratio of the region 3 was 3% in all the examples. In order to evaluate the influence of the Si content, Invention Examples 18 to 20, 22, 23 and Comparative Examples 35 and 36 having different Si contents were prepared. In order to change the area ratio of Si contained in the composite target, the area ratio of the region 2 was changed. Inventive Example 18 is 0.5%, Inventive Example 19 is 1%, Inventive Example 20 is 3%, Inventive Example 22 is 15%, Inventive Example 23 is 30%, and Comparative Example 35 contains Si. None, Comparative Example 36 was 51%. In order to evaluate the influence of the Al content on the tool life, Ti in region 1, Si in region 2, B4C in region 3, and Al in region 4 are uniformly embedded at a predetermined area ratio. 25 and 26 and Comparative Examples 37 and 38 were prepared. In order to change the area ratio of Al, the area ratio of the region 4 was changed. Inventive Example 25 was 3%, Inventive Example 26 was 3%, Comparative Example 37 was 10%, and Comparative Example 38 was 15%. Here, the area ratio of the region 2 containing Si was 7%. In order to investigate the influence of the intermediate layer, Examples 27 to 34 of the present invention coated the film of Example 1 of the present invention on the upper layer side of the intermediate layer. Among the sputtering evaporation sources arranged in four in the vacuum vessel, intermediate layer coating targets were placed on the remaining two numbers 1 and 2, respectively, and 8 kW of power was supplied to form a 1 μm intermediate layer. The shapes of numbers 1 and 2 are the same as the shapes of numbers 3 and 4. Regions 5 to 7 were set as targets 1 and 2 for the intermediate layer coating target. Inventive Examples 27 to 30 have the area 5 as 70% and the Area 6 as 30%, and the Inventive Examples 31 to 34 as the area ratio of 65% for the area 5, 30% for the area 6, and 5% for the area 7. used. Using the test piece obtained by the above method, the film composition was analyzed by EPMA. Table 1 shows the target material of the sputtering evaporation source and the coating composition.

  Next, using the obtained test piece, qualitative analysis of the compound by X-ray photoelectron spectroscopic analysis, abundance ratio measurement, film hardness, and macroparticle area ratio measurement by a scanning electron microscope were performed. As a result of qualitative analysis, it was confirmed that nitrides and carbides were present in Invention Examples 1 to 34 and Comparative Examples 35 to 38. The compound abundance ratio calculated from the area area ratio by Si2p peak fitting by X-ray photoelectron spectroscopic analysis is represented by N (70) for nitride and C (30) for carbide in the case of the present invention example 1, for example. The evaluation results are shown in Table 2.

  On the other hand, as a comparative example, a Ti80Si20B alloy target was used, nitrogen and acetylene were introduced, and a comparative example 39 in which a (Ti85Si15) (BCN) film was coated by 2 μm was prepared by the AIP method. Using Ti, TiSi compound, and B4C powder as raw materials, a target was prepared by hot pressing, and Comparative Example 40 was formed by coating 2 μm of a (Ti85Si15) (BCN) film by AIP method. A target was prepared by hot pressing using Ti, SiC, and B powders as a raw material, and Comparative Example 41 was formed by coating the (Ti85Si15) (BCN) film with a thickness of 2 μm by the AIP method. While discharging the Ti85Si15 target by the AIP method, the B4C target is discharged by the sputtering method, and TiSiN and BCN are laminated with a period of several to several tens of nanomails, and a film having an average composition of (Ti85Si15) (BCN) is covered by 2 μm. Comparative Example 42 was prepared. A comparative example 43 in which Ti80Si20 and TiB2 were sputtered using a hot press target, nitrogen and acetylene were introduced, and a (Ti85Si15) (BCN) film was coated with 2 μm was prepared. These evaluation results are shown in Table 3.

  From Tables 2 and 3, it was confirmed from the results of X-ray photoelectron spectroscopy that nitrides and carbides were present in the coatings of Invention Examples 1 to 34 and Comparative Examples 35 to 38. In Comparative Examples 39 to 43, the presence of any material other than nitride and boride was not confirmed in the film. Therefore, even if a target containing carbide is produced by a normal AIP method, a hard film in which a compound is present in the film is not obtained, and the adhesion resistance is not improved.

  The results of measuring Example 2 of the present invention by X-ray photoelectron spectroscopy are shown in FIGS. FIG. 1 shows a wide spectrum. FIG. 2 shows a C1s narrow spectrum, confirming the presence of carbides. A peak corresponding to free carbon was also observed. FIG. 3 shows the N1s narrow spectrum, confirming the presence of nitride. FIG. 4 shows the Si2p narrow spectrum. From FIG. 4, it was confirmed that Example 2 of the present invention had two types of peaks, carbide and nitride, and at least SiN and SiC were present in the film. From this, it is thought that the example 2 of this invention has the carbide phase in the nitride phase. On the other hand, when it is present as Si (CN), it is considered that it is composed of only one kind of peak, and this time, this was not the case. From FIG. 4, the abundance ratio of the nitride phase and the carbide phase of Example 2 of the present invention was calculated from the area area ratio by Si2p peak fitting. As a result, it was confirmed that nitride was present at a ratio of approximately 80% and carbide at a ratio of approximately 20%. From FIG. 4, the presence of Kr in the film could also be confirmed. FIG. 5 shows the X-ray diffraction results of Example 2 of the present invention. A nitride-only compound having a cubic B1 structure is qualitatively analyzed, and the carbide may exist as an amorphous phase or may not be detected due to peak overlap.

  A ball-on-disk wear test was performed using Example 1 of the present invention and Comparative Example 39. The test was carried out using a tribometer manufactured by CSM, coated with the SNMN432-shaped fine cemented carbide alloy as a disk and coated with the coating of Example 1 and Comparative Example 39, and used as a ball and made of SUJ2 having a diameter of 6 mm. did. The test conditions were a radius of rotation of 1.5 mm, a rotation speed of 3 cm per second, a load of 2 N, a sliding distance of 30 m, a test temperature of 25 ° C., a test humidity of 59%, and the atmosphere. Observation photographs after the test are shown in FIGS. FIG. 6 shows an optical micrograph of the disc wear scar of Example 1 of the present invention and FIG. 7 of Comparative Example 39. FIG. 8 shows the results of iron element mapping analysis by SEM-EDX of the disk wear scar of Example 1 of the present invention and FIG. 9 of Comparative Example 41. FIG. 10 shows an optical micrograph of the ball wear scar of Example 1 of the present invention and FIG. 11 of Comparative Example 39. From FIG. 6 to FIG. 11, the hard coating surface of Example 1 of the present invention showed almost no adhesion of iron and showed excellent adhesion resistance. On the other hand, in Comparative Example 39, iron adhesion was intense. Further, the wear volume of the ball, that is, the amount of SUJ2 attached to the hard coating surface or lost due to wear is 13.0 mm3 in Comparative Example 41, 4.3 mm3 in Invention Example 1, and Example 1 in the present invention is Affinity for iron was lower. On the other hand, the wear depth of the disk coated with the hard film was 0.9 μm in the present invention example 1 compared with 1.5 μm in the comparative example 39, and the present invention example 1 was also excellent in wear resistance. From this result, it was confirmed that the hard coating of the present invention showed excellent adhesion resistance and wear resistance to iron-based materials.

(Example 2)
The tool life was evaluated by the following method using a ball end mill coated with the hard coating of the present invention. The tool life evaluation results reached a cutting length where the flank wear width reached 0.1 mm, or extremely unstable machining conditions such as sparks, abnormal noise, flaking of the machined surface, and burning. The cutting length was defined as the cutting life. Moreover, the cutting life of less than 10 m was rounded down. The evaluation results of the tool life are also shown in Tables 2 and 3.
(Tool evaluation conditions)
Tool: 2-flute ball end mill, diameter 10 mm
Cutting method: Ultra-high speed bottom finish machining Material: HPM38, Hitachi Metals, Hardness, HRC52
Cutting: axial direction, 0.4mm, pick feed, 0.2mm
Spindle speed: 10kmin- ¹
Table feed: 4m / min
Cutting oil: None, dry cutting

  The tool life of Inventive Examples 1 to 17 and Comparative Examples 39 to 43 were compared. The tool life of Comparative Examples 39 to 43 is 300 to 380 m while that of Inventive Examples 1 to 17 is 580 to 830 m, and the Inventive Examples 1 to 17 are 1.5 to 2.1 times longer tools. The tool life was shown, and a much longer tool life was obtained. In the wear states of Examples 1 to 17 of the present invention, the adhesion of the workpiece was remarkably small, and the tool life was reached by uniform wear. In the present inventions 1 to 17, since the adhesion of the workpiece is remarkably reduced, there is no burr of the workpiece, the finished surface is glossy, and the finished quality of the workpiece is also marked. Improved. The lubrication characteristics have been greatly improved, the adhesion of the work material has been suppressed, chipping of the cutting edge has been reduced, and the tool life has been greatly improved. Machining accuracy in finishing has also improved, and it has become extremely effective in improving productivity and reducing costs. On the other hand, in the wear state of Comparative Examples 39 to 43, the adhesion of the workpiece to the coating surface was remarkable, and the tool life was reached due to chipping of the cutting edge and abnormal wear. Comparative Examples 39 to 43 had poor adhesion resistance, and a large amount of iron adhered to the tool cutting edge. As a result, the wear progressed faster due to abnormal wear, and the tool life was short. Moreover, since the (TiAl) N film | membrane used for evaluation reached the tool life at 300 m, it has confirmed that the effect of this invention was especially remarkable.

The influence of Si content was compared. Samples differing only in the Si content from Invention Examples 18 to 23, Comparative Example 35, and Comparative Example 36 were produced. Inventive Examples 18 to 23 had a tool life of 540 to 640 m, and a long tool life was obtained. In particular, the tool life of a cutting tool coated with a film having an Si content of 8 to 27 atomic% in terms of the atomic ratio of the metal element was long, and the Si content was more preferable. In Comparative Example 35, Si was not contained, but the hardness was low and the tool life was not improved. Comparative Example 36 is a case where the Ti content is 49 atomic% and the Si content is 51 atomic%. Not only the hardness is low, but also in the evaluation of the adhesion resistance by a tribometer, iron adhesion is Since the adhesion resistance was severely reduced, the improvement of the tool life could not be confirmed. Based on the above results, the coated cutting tool of the present invention has the brittleness and affinity with iron-based work materials and adhesion without sacrificing the high hardness and excellent wear resistance of the Si-containing coating. It was possible to improve lubricity such as sliding characteristics. And it became possible to improve the durability of the tool remarkably and showed a long tool life stably. Furthermore, it was confirmed that the processing accuracy in finishing processing was improved and it was extremely effective for improving productivity and reducing costs.
Next, tool life was compared for the effect of Al content. Samples having different Al contents were prepared and compared in Invention Examples 24 to 26 and Comparative Examples 37 and 38. As the Al content increased, the decrease in hardness and the adhesion resistance by the tribometer also decreased the adhesion resistance due to the increase in the Al content, and the tool life also decreased. In particular, in Comparative Examples 37 and 38 in which the Al content was 10% and 15% in terms of the atomic ratio of the metal element, improvement in tool life could not be confirmed. As the Al content increased, the crystal structure of the film became hexagonal, or a mixture of hexagonal and cubic crystals, which was a major factor. By adding Al, the hardness tends to decrease, but the oxidation resistance is improved. Therefore, when the Si content is 15% in terms of the atomic ratio of the metal element, the allowable content of Al is that of the metal element. The atomic ratio is less than 10 atomic%. When the Si content is more than 15% in terms of the atomic ratio of the metal element, the allowable content of Al decreases. Accordingly, the Al content of the hard coating of the present invention is preferably less than 10 atomic% in terms of the atomic ratio of the metal element.
The tool life of Examples 27 to 34 of the present invention when using an intermediate layer which is a preferred form of the present invention was evaluated. By using the intermediate layer, the tool life was further improved by 1.3 to 1.8 times compared to Example 1 of the present invention. This is because the hard coating of the present invention contains a large amount of Si, and the reactivity between this Si and Co in the cemented carbide substrate is high, and the crystal grain size is relatively small, so it has a columnar structure. By using the intermediate layer, Co diffusion suppression from the base material and adhesion were improved, and the tool life was improved. In particular, an intermediate layer mainly composed of nitrides of Al and Cr is optimal. A long tool life was obtained by adding Si, Nb, Y to the nitrides of Al and Cr.

FIG. 1 shows the results of X-ray photoelectron spectroscopy analysis of Example 2 of the present invention. FIG. 2 shows the results of X-ray photoelectron spectroscopy analysis of Example 2 of the present invention. FIG. 3 shows the result of X-ray photoelectron spectroscopy analysis of Example 2 of the present invention. FIG. 4 shows the result of X-ray photoelectron spectroscopy analysis of Example 2 of the present invention. FIG. 5 shows the X-ray diffraction results of Example 2 of the present invention. FIG. 6 shows an optical micrograph of the disc wear scar of Example 1 of the present invention. FIG. 7 shows an optical micrograph of the disc wear scar of Comparative Example 39. FIG. 8 shows the SEM-EDX analysis result of the disk wear scar of Example 1 of the present invention. FIG. 9 shows the SEM-EDX analysis result of the disc wear scar of Comparative Example 39. FIG. 10 shows an optical micrograph of the wear scar on the ball of Example 1 of the present invention. FIG. 11 shows an optical micrograph of the wear scar on the ball of Comparative Example 39.

Claims (1)

The hard coating is atomic%, Si is 2 to 50%, M component is 50 to 98%, where M component is at least one selected from Ti, Cr, Zr, Nb, W, Mo, V. The hard film is characterized in that a carbide phase exists in the nitride phase.