JP2012152878A - Coating tool having superior wear resistance and slide resistance, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating tool having superior wear resistance and slide resistance, in a tool such as a cutting tool and a metal mold tool which are used in a severe use environment, and to provide manufacturing method of the same.SOLUTION: The coating tool is obtained by coating a hard membrane on the surface of a base material of the tool via an intermediate membrane, the hard membrane is an SiC membrane which is larger than Si in atom ratio, and includes a hexagonal crystal structure phase in organization, the intermediate membrane is a nitride or a carbon compound composed of AlxMy, (Here, x, y show the atom ratios, x+y=100, 40≤x≤95, and 5≤y≤60, and M is one or more kinds selected from Ti, Cr, V and Nb). The coating tool has a cubic crystal structure at the side of the base material, and a hexagonal crystal structure at the side of the hard membrane, and has superior wear resistance and slide resistance.

Description

  The present invention relates to a coated tool that is applied to, for example, a cutting tool and a die, which requires excellent wear resistance and sliding properties, and a manufacturing method thereof.

  Conventionally, surface treatment for coating various ceramic films on the surface of a substrate has been adopted for cutting tools and the like for the purpose of improving the durability thereof. Among various coating means, a coating process by a physical vapor deposition method capable of coating a multi-component hard film with high adhesion is increasing.

  In recent years, work materials have become harder and higher speed machining has been demanded, and the usage environment of cutting tools has become increasingly severe. Therefore, in order to cut a high hardness material at a high speed, development of a hard film having high hardness and high heat resistance is required. For example, as a multi-element hard film, a hard film made of a multi-element nitride containing Al and further containing Nb, Cr, Ti, Si or the like as shown in Patent Document 1 has been studied. However, in a severe usage environment of cutting tools in recent years, the wear resistance may not be sufficient.

  On the other hand, SiC is known as a ceramic material having high hardness and high heat resistance. SiC has a high hardness of 40 GPa or more in bulk ceramics, and is excellent in wear resistance and oxidation resistance. Therefore, application is advanced as a hard film for cutting tools.

As a study on application of SiC film to a tool, for example, in Patent Document 2, cluster ions are excited by using a SiC sintered body as a target by RF magnetron sputtering using a high-frequency current to form a SiC film on the surface of a substrate. A filming technique is disclosed. However, the SiC film of Patent Document 2 has a problem that it is amorphous, has low hardness, and has insufficient wear resistance.
Also, in Patent Document 3, an SiC film having excellent wear resistance coated with a crystalline SiC film having a cubic crystal structure phase by adjusting the processing atmosphere of a magnetron sputtering method using SiC targets having different composition ratios. Is disclosed.

Japanese Patent Laid-Open No. 2007-11981 JP 2007-90483 A JP 2009-293111 A

Compared to the amorphous SiC film, the film containing crystalline SiC of Patent Document 3 has high wear resistance, and does not generate cracks due to amorphous crystallization at high temperatures, and thus has high temperature characteristics. However, in recent years, the usage environment of cutting tools and molds has become severer year by year, and the pressure applied to the work surfaces of cutting tools and molds during molding is high, and the friction with the work material has also increased. Higher wear resistance and sliding properties are required for hard coatings coated on the surface. For this reason, the conventional SiC film may not be sufficient to further improve the life under the recent severe environment.
And it discovered that it was more effective to further improve the adhesion between the crystalline SiC film and the substrate.

  The present invention has been made in view of such circumstances, and a coated tool coated with a high adhesion strength so as not to peel off a SiC film having excellent wear resistance and sliding properties even in a severe use environment, and A manufacturing method thereof is provided.

  The inventors of the present invention particularly improve the wear resistance and the sliding property simultaneously by including a hexagonal crystal structure phase in the structure of the SiC film and at the same time including a large amount of carbon atoms in the film. I found it effective. And it discovered that adhesiveness and abrasion resistance were remarkably improved and the performance of the coated tool was improved by controlling the respective crystal structures on the substrate side and the hard film side of the intermediate film.

  That is, the present invention is a coated tool in which a hard film is coated on the surface of a base material of a tool via an intermediate film, and the hard film contains more C than Si in an atomic ratio and has a hexagonal crystal structure phase in the structure. The intermediate film is a nitride or carbonitride composed of AlxMy (where x and y indicate atomic ratios, x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, where M is one or more selected from Ti, Cr, V, and Nb), and the base material side has a cubic crystal structure, and the hard coating side has a hexagonal crystal structure. It is a coated tool with excellent characteristics.

  The intermediate film preferably has an increased content of Al from the substrate side toward the hard film side. Furthermore, it is preferable that the intermediate film contains one or more selected from Si, Y, and B in an atomic ratio of 20% or less. Furthermore, it is preferable that the intermediate film contains at least Si, and the Si content increases from the base material side toward the hard film side.

  The amount of C in the hard coating is preferably 70% or less in terms of atomic ratio. Furthermore, the structure of the hard film preferably contains an amorphous hexagonal crystal structure phase, and in the electron diffraction using a transmission electron microscope, the hexagonal crystal plane of (101) or (002) has the maximum strength. It is preferable to show.

Further, the above-described coated tool of the present invention is a manufacturing method in which a hard film is coated on the surface of a base material of the tool via an intermediate film by physical vapor deposition, for example, and the intermediate film is made of AlxMy ( However, x + y = 100, 40 ≦ x ≦ 95, 5 ≦ y ≦ 60, M is one or more selected from Ti, Cr, V, and Nb) using a plurality of targets having different compositions,
Nitride or carbonitride composed of AlxMy (where x and y are atomic ratios, x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, M is Ti, Cr, V, Nb The base material side forms a cubic crystal structure, and the hard film side forms a hexagonal crystal structure,
The hard coating can be coated by using a SiC composite target containing a C phase of more than 0 and less than 25% by volume, and by sputtering with an average power applied to the SiC composite target of 2 kW or more. .

In the coating of the intermediate film, the Al content increases from the base material side toward the hard film side by increasing the power applied to the target having a high Al content among the multiple targets. It is preferable to coat so as to.
The coating of the intermediate film satisfies the relationship of AlxMy (where x + y = 100, 40 ≦ x ≦ 95, 5 ≦ y ≦ 60, M is one or more selected from Ti, Cr, V, and Nb), and Si It is preferable to use one or more targets containing 20% or less of one or more selected from Y, B in atomic ratio. Furthermore, in the coating of the intermediate film, at least one target containing Si is used, and by increasing the power applied to the target containing Si, Si is directed from the substrate side toward the hard film side. It is preferable to coat so that the content of is increased. The C phase of the SiC composite target is preferably 2% or more by volume ratio.

  Since the coated tool provided by the present invention is coated with a SiC film having excellent wear resistance and sliding properties in a state having high adhesion, it can exhibit excellent durability. Therefore, it can be applied to a cutting tool or a tool used in a mold used in a severe use environment.

FIG. 3 is a limited-field diffraction image of sample No. 2 with a beam diameter of 680 nm measured by a transmission electron microscope, and is a view showing an example of a coated tool of the present invention. It is a cross-sectional photograph of the sample number 2 by a transmission electron microscope, and is a figure which shows an example of the coating tool of this invention. It is a micro part electron beam diffraction image of the sample diameter 2 of the beam diameter of 3 nm by a transmission electron microscope, and is a figure which shows an example of the coating tool of this invention.

  The inventors of the present invention are particularly effective in improving the wear resistance and the sliding property simultaneously by including a hexagonal crystal structure phase in the structure of the SiC film and simultaneously including a large amount of carbon atoms in the film. I found out. Further, the present inventors have found that in order to further improve the performance as a coated tool, an intermediate film for improving adhesion is provided, specifically, an intermediate film having a controlled crystal structure is provided between the base material and the hard film. Hereinafter, the configuration requirements of the present invention will be described.

First, the hard film of the present invention will be described in detail.
In the present invention, since the structure of the SiC film contains a tough and hard hexagonal crystal structure phase, the hardness is remarkably increased, and can reach, for example, 40 GPa or more.
In addition, by including a hexagonal crystal structure phase in the SiC structure and adding a large amount of carbon atoms with excellent lubrication performance to the hard coating, the wear of the entire hard coating has a high hardness of 40 GPa or more. Since the coefficient can be reduced, it is possible to improve the wear resistance and the sliding characteristics together.
When the C content in the SiC film is excessively increased, the wear resistance is lowered. Therefore, the C content is preferably 70% or less in terms of atomic ratio.

The structure of the hard film is preferable because the amorphous structure contains a hexagonal crystal structure phase, which causes distortion in the hard film and increases the compressive residual stress, thereby further improving the hardness of the hard film.
In order to confirm whether the structure of the hard film contains a hexagonal crystal structure phase, electron diffraction using a transmission electron microscope is preferable. In X-ray diffraction using an X-ray diffractometer, when many amorphous or fine crystals of 1 to 2 nm or less are included, the diffraction peak intensity is weak, so the structure of the hexagonal crystal is in the structure of the hard film. It may be difficult to confirm whether or not it is included.
Further, those having a (101) or (002) hexagonal crystal plane exhibiting the maximum strength by electron beam diffraction using a transmission electron microscope have high crystallinity, high hardness, and excellent wear resistance.
In the present invention, the structure of the hard coating is amorphous is a structure in which a clear periodic structure is not confirmed and a crystal diffraction pattern of electron diffraction is not confirmed in observation of the hard coating with a transmission electron microscope. That means. Similarly, the case where the hard coating is composed of a texture of fine crystal particles of 1 to 2 nm or less in which the hard film does not have a periodic structure and is difficult to generate a diffraction pattern is also included in the amorphous state in the present invention.
In order to uniformly apply the residual compressive stress to the entire hard coating, it is preferable that the hexagonal crystal structure phase is finely dispersed in the hard coating. For example, by setting the average crystal grain size of hexagonal crystals to 20 nm or less, the dispersion becomes uniform and the residual compressive stress can be uniformly applied, which is effective in improving the wear resistance and is preferable. The crystal grain size tends to increase slightly as the amount of C in the hard coating increases.

The hard film of the present invention may contain oxygen and other impurities inevitably contained. And the structure of the hard film of the present invention includes a hexagonal crystal structure phase and has a film structure containing a large amount of carbon atoms, thereby exhibiting excellent wear resistance and sliding properties. Therefore, even if other elements are added to the SiC film of the present invention, the effect of the present invention can be exhibited without loss by having the structure of the hard film of the present invention. However, if the addition amount of other elements is more than 10% in terms of atomic ratio, the wear resistance is remarkably lowered. More preferably, it is 5% or less, More preferably, it is 1% or less.
In addition, if necessary, a functional film such as nitride, carbide, oxide, boride, sulfide, or metal may be coated on the outermost layer.

Next, the intermediate film of the present invention will be described in detail.
The intermediate film is provided in order to further improve the adhesion of the hard film, but if the heat resistance and wear resistance of the intermediate film itself are low, the characteristics of the entire film tend to be lowered. Therefore, the composition of the intermediate film is a nitride or carbonitride composed of AlxMy (where x and y indicate atomic ratios, x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, M Is one or more selected from Ti, Cr, V, and Nb).
In the intermediate film of the present invention, addition of Al is essential, and by setting the Al content to 40 ≦ x ≦ 95, the wear resistance and heat resistance of the entire film can be improved. If it is less than this, the heat resistance tends to decrease. If it is more than this, the wear resistance tends to decrease.
By setting the amount of one or more selected from Ti, Cr, V, and Nb to be 5 ≦ y ≦ 60, the wear resistance of the entire coating can be improved. If it is less than this, the wear resistance tends to be lowered. When it is more than this, the heat resistance tends to decrease.

In the present invention, the intermediate film is controlled within the above composition range, and the hard film side has a hexagonal crystal structure similar to that of the hard film in order to further improve the adhesion, and the substrate side has crystallinity. It has been found that by using a cubic crystal structure with high hardness and high hardness, it is possible to achieve higher adhesion to the hard film without reducing the wear resistance.
The crystal structure of the intermediate film can be specified from the crystal plane showing the maximum intensity of electron beam diffraction by a transmission electron microscope, as in the case of the hard film.
In the present invention, the crystal structure of the intermediate film on the base material side means that the cubic crystal structure shows the maximum strength by electron beam diffraction with a transmission electron microscope. The term “hexagonal crystal structure on the hard film side of the intermediate film” means that the hexagonal crystal structure shows the maximum strength by electron beam diffraction using a transmission electron microscope.

The intermediate film tends to have a hexagonal crystal structure when the Al content is large, and the intermediate film has a gradient composition that increases the Al content from the substrate side toward the hard film side. It is preferable because the crystal structure tends to be gently inclined from cubic to hexagonal and adhesion strength is improved.
Further, the intermediate film preferably contains at least one selected from Si, Y, and B at 20 atomic% or less, so that the crystal grain size is further refined and the hardness and oxidation resistance are improved. If the amount added is larger than this, the toughness of the film tends to decrease, and it becomes difficult to control the crystal structure.
Further, when the intermediate film contains Si, it tends to be a hexagonal crystal structure even if the Al content is small. Therefore, by adopting a gradient composition that increases the Si content from the base material side toward the hard film side, the crystal structure of the intermediate film tends to be gradually inclined from cubic to hexagonal, and the adhesion strength is improved. preferable. When the content of Si increases, it tends to be amorphous when the content of Al is large.

Hereinafter, the production method of the present invention will be described.
In the SiC film formation by the conventional sputtering method, since the electrical resistance of the SiC target is high, when the power applied to the target is increased, abnormal discharge (arcing) occurs on the target surface, and the discharge becomes unstable. There was a problem. Therefore, in order to coat the SiC film under stable film formation conditions, it is necessary to coat the film with low film formation energy while suppressing the power applied to the target. It was difficult to obtain a SiC film containing a crystal structure phase of crystals. In addition, since the power applied to the target is low, there is a problem that the film formation rate is low and the productivity is low.

  The inventors have intensively studied methods for improving the conductivity of the target. And by using SiC composite target containing a specific amount of C phase, which is made by hot pressing by mixing C powder with SiC powder to increase conductivity, the electrical conductivity of the target surface is significantly improved. It has been found that high power can be supplied.

  As described above, in the present invention, the SiC composite target is a SiC target containing a specific amount of C phase. If an SiC composite target containing a large amount of C phase is used, the SiC film, which is a hard film, may contain more C than necessary and wear resistance may deteriorate. Therefore, in order to obtain a preferable hard film, the C phase in the target is set to 25% or less by volume ratio. In order to improve the electric conductivity of the target surface, the C phase in the target is preferably 2% or more by volume.

In order to more efficiently include a hexagonal crystal structure phase with high crystallinity in the structure of the SiC film, the average power applied to the SiC composite target is set to 2 kW or more. More preferably, it is 3 kW or more. When the average power applied to the target is less than 2 kW, the film formation energy is low, the amorphous structure tends to be formed, and it becomes difficult to incorporate a hexagonal crystal structure phase in the SiC structure. Further, productivity is not preferable because the film formation rate is low.
In order to stabilize the load and power supply of the apparatus, the average power applied to the target is preferably 10 kW or less.

In covering the intermediate film, a specific crystal structure is formed on the substrate side and the hard film. For example, it is made of AlxMy (where x and y are atomic ratios, x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, and M is selected from Ti, Cr, V, and Nb. A plurality of targets having different compositions on the substrate side and the hard coating side. Then, by selecting nitrogen or a hydrocarbon gas as a reaction gas and controlling the film formation atmosphere, a nitride or carbonitride composed of AlxMy (where x and y indicate an atomic ratio, x + y = 100, and 40 ≦ x ≦ 95 and 5 ≦ y ≦ 60, where M is one or more selected from Ti, Cr, V, and Nb), and the substrate side has a cubic crystal structure, and the hard coating side has a hexagonal crystal. The structure can be controlled.
The intermediate film of the present invention tends to have a hexagonal crystal structure when the Al content increases, and a target of 40 ≦ x ≦ 65 is used on the substrate side, and 65 <x ≦ 95 is used on the hard film side. It is preferable to control the crystal structure.
Furthermore, among the plurality of targets, if the power applied to the target having a large Al content is increased and the gradient composition is such that the Al content increases from the base material side toward the hard coating side, the intermediate coating film It is preferable that the crystal structure tends to be gradually inclined from a cubic crystal to a hexagonal crystal structure, and adhesion is improved.

AlxMy (where x and y are atomic ratios, x + y = 100, 40 ≦ x ≦ 95, 5 ≦ y ≦ 60, and M is one selected from Ti, Cr, V, and Nb) In addition, by using one or more targets satisfying the above relationship) and containing one or more selected from Si, Y, and B in an atomic ratio of 20% or less, the crystal grain size of the intermediate coating is refined, and the hardness And oxidation resistance is improved.
By using one or more targets containing at least Si, a hexagonal crystal structure is easily obtained even if the Al content is small. Therefore, by increasing the electric power applied to the Si-containing target and making the gradient composition in which the Si content increases from the base material side toward the hard film side, the intermediate film is made from cubic to hexagonal. This is preferable because it tends to be gently inclined toward the crystal structure and the adhesion is improved.

  The crystal structure of the intermediate film can also be controlled by a negative bias voltage applied to the substrate among the film forming conditions. That is, when the negative bias voltage increases, a cubic crystal structure tends to be formed, and when the negative pressure bias voltage decreases, a hexagonal crystal structure tends to be formed.

The sputtering method for coating the hard coating of the present invention uses a glow discharge generated by applying a bias voltage to a base material, using the target as a cathode, and applying electric power to the target, and target components by ions colliding with the target. This is a film formation method utilizing a sputtering phenomenon that blows off the film.
For example, in addition to DC (direct current) sputtering method, RF (radio frequency) sputtering method, non-equilibrium magnetron sputtering method, sputtering using a pulse power supply, etc., HIPIMS (High Power Impulse Magnet Sputtering) and HPPPMS (High Power Pulse Magnetron Sputtering). The film can also be formed by a high-power pulse magnetron sputtering method in which the ionization rate of the target component represented by) is high.
Film formation by the high-power pulse magnetron method is preferable because the crystallinity of the SiC film is improved and the hardness is further increased.
The intermediate coating of the present invention is not limited to sputtering, and physical vapor deposition such as arc ion plating or ion plating can be applied. In any case, the crystal structure of the intermediate film can be controlled by using a plurality of targets depending on the coating method.

<Preparation of sample for characteristic evaluation>
For mechanical property evaluation, a high-speed steel SKH51 specified in JIS was prepared, and this was tempered at 180 to 580 ° C. by tempering at 540 to 580 ° C. after tempering at 1180 ° C. in a vacuum and quenching with nitrogen gas cooling A thing was used. As the dimensions of the substrate, a cylindrical shape having a thickness of 5 mm and a diameter of 20 mm was used.
The surface of the cylindrical base material is polished with # 1000 and # 1500 polishing paper, and then subjected to electrolytic polishing. Finally, an aero lapping process (Aero Lap YT-300 manufactured by Yamashita Towers Co., Ltd.) is used. The surface roughness was adjusted to 0.02 μm Ra and 0.2 μm Rz. Then, it was degreased by ultrasonic cleaning in a hydrocarbon solvent.

  As a film forming means, a sputtering method was employed, and an apparatus equipped with four sputter evaporation sources (evaporation source numbers 1 to 4) capable of continuously forming an intermediate film and a hard film in the same chamber was used. Among them, SiC targets for hard coatings were installed in two machines, and alloy targets for intermediate coatings were installed in two machines.

The target will be described.
For the formation of the hard coating, an SiC composite target containing SiC powder and C powder as raw materials, molded by hot pressing, and containing a specific amount of C phase was used. Moreover, the normal SiC target which does not contain C phase was also prepared.

The SiC95-C5 target was prepared by mixing SiC powder and C powder in a volume ratio of 95: 5. The produced target had an oxygen content of 871 ppm.
A SiC90-C10 target was prepared by mixing SiC powder and C powder in a volume ratio of 90:10. The produced target had an oxygen content of 638 ppm.
The SiC80-C20 target was prepared by mixing SiC powder and C powder at a volume ratio of 80:20. The produced target had an oxygen content of 426 ppm.
The SiC target was a normal SiC target containing no C phase, and the oxygen amount was 612 ppm.
An alloy target was used for forming the intermediate film. The size of each target was 500 mm × 88 mm and the thickness was 10 mm. Table 1 shows the targets used.

The film forming process will be described.
The bias power source is connected to the base material and independently applies a negative bias voltage to the base material. The substrate rotates at two revolutions per minute and revolves through a fixing jig and a sample holder. The distance between the substrate and the target surface was 50 mm. The introduced gas was N ₂ , Ar, and Kr, and was introduced from the gas supply port.

First, heating was performed for 90 minutes with the substrate temperature at 500 ° C. by the heater in the film forming apparatus, and after the pressure in the vacuum vessel (chamber) reached 4 × 10 ⁻³ Pa, Ar gas was removed. It introduced in the vacuum vessel and the pressure in a furnace was 0.2 Pa. Then, a DC bias voltage of −200 V was applied to the substrate. The substrate was cleaned with Ar ions for 10 minutes.

The pressure in the container is evacuated to 1 × 10 ⁻³ Pa, the temperature of the base material is kept constant at 450 ° C., and N is adjusted so that the pressure in the container becomes 600 mPas under a constant flow rate of 500 ml of Ar gas. _Two gases were introduced. Then, an intermediate film was formed by setting the bias voltage to −120 V and the anode voltage to −110 V.

  In Sample Nos. 1 to 12, 14, 15, 17, and 18, the film forming conditions were adjusted so that the intermediate film was an inclined structure layer. First, an average power of 6 kW was applied to evaporation source number 1 to form a film for 5000 seconds (approximately 0.5 μm). Thereafter, the average power of 2 kW is applied to the evaporation source number 2 and at the same time, the average power of the evaporation source number 2 is increased to 6 kW at a rate of 0.5 W / second, and the average power of the evaporation source number 1 is increased from 6 kW to 2 kW. Decreasing at a rate of 0.5 W / second, the step of the inclined structure layer was performed for about 7500 seconds to form an approximately 1 μm inclined film. Thereafter, the power supply of the evaporation source number 1 was stopped, and the evaporation source number 2 was formed for 5000 seconds (approximately 0.5 μm).

  Sample No. 13 was a sample without the above gradient structure layer by the following procedure. That is, after film formation with evaporation source number 1 was performed for 10000 seconds (approximately 1 μm), power supply to evaporation source number 1 was stopped and film formation with evaporation source number 2 was performed for 10,000 seconds (approximately 1 μm). Was deposited.

Thereafter, the pressure in the container is evacuated to 1 × 10 ⁻³ Pa, the temperature of the substrate is kept constant at 450 ° C., and the pressure in the container becomes 580 mPa under a constant flow rate of 500 ml of Ar gas. Was introduced with Kr gas. And the bias voltage was set to -120V, the anode voltage was set to -110V, and the hard film was formed. In Sample No. 16, a hard film was formed without forming an intermediate film.

Sample numbers 1 to 17 used SiC composite targets containing a certain amount of C phase.
Electric power of 3 kW was applied to evaporation source number 3 to start discharging. After 500 seconds, an output of 3 kW was applied to the evaporation source number 4 to start discharging, and an approximately 2 μm SiC film was formed at the evaporation source numbers 3 and 4.

Sample No. 18 used a normal SiC target containing no C phase. In this case, when the electric resistance of the target surface was high and the electric power applied to the target was set to be larger than 1 kW, abnormal discharge occurred on the target surface and film formation could not be performed. Therefore, the power applied to the target was set to 1 kW.
Each coated sample was taken out from the container after being cooled to 200 ° C. or less, and the film characteristics were evaluated.

<Film composition>
The coating composition was analyzed using an electron probe microanalyzer (EPMA; JXA-8900R manufactured by JEOL Ltd.). The analysis was carried out after mirror polishing of the film cross section in which the test piece was tilted 5 degrees with respect to the outermost surface of the film. The analysis value was measured five times with an acceleration voltage of 15 kV, a sample current of 0.2 μA, and a counting time of 10 seconds, and the average value was obtained. Table 2 shows the analysis results of the coating composition. Numerical values indicate atomic ratios.

  It is considered that oxygen qualitatively determined by quantitative analysis was mixed into the target or unavoidably mixed with other factors. In the film formed with the SiC composite target, C / Si was 1.38 to 1.73, and each contained a large amount of C. In film formation using a normal SiC target, a little Si was contained relative to C. The intermediate film had almost the same composition as the alloy target.

<Crystal structure and crystal grain size>
In order to measure the crystal structure of the intermediate coating and the hard coating, the cross section of the coating was observed using a transmission electron microscope (TEM). First, a sample was cut and bonded onto a dummy substrate using an epoxy resin, and then cut, Mo reinforcing ring bonding, polishing, dimple ring, and Ar ion milling were performed to prepare a cross-sectional TEM sample. Carbon vapor deposition was performed before the measurement. The equipment was a JEM-2010F type field emission transmission electron microscope manufactured by JEOL Ltd., and the acceleration voltage was 200 kV. The limited field diffraction image had a camera length of 50 cm and a limited field area of 680 nm in beam diameter. The minute portion where the lattice image was observed was subjected to minute portion electron beam diffraction (with a beam diameter of 3 nm or less), and the crystal structure of the film was identified from the electron beam diffraction pattern that appeared most strongly. The average crystal grain size was measured from the observed lattice image. Table 3 shows the measurement results.

FIG. 1 shows a limited field diffraction image of a hard film of Sample No. 2 having a beam diameter of 680 nm by a transmission electron microscope. A crystal diffraction pattern corresponding to the hexagonal crystal plane of (002) or (101), (110), (112) or (200) is confirmed. Among them, it is confirmed that the (002) or (101) hexagonal crystal diffraction pattern is brightest and shows the strongest intensity.
Similarly, Sample Nos. 1 and 3 to 17 formed with the SiC composite target containing the C phase showed the strongest intensity in the (002) or (101) hexagonal crystal diffraction pattern.
In sample number 18 using a normal SiC target, the crystal diffraction pattern was not confirmed, and the sample was amorphous.

FIG. 2 is an example of a cross-sectional photograph of the hard film of Sample No. 2 using a transmission electron microscope. It is confirmed that both a clear lattice image and a portion without a periodic structure exist. The major axis of the observed lattice image was approximately 10 nm or less. On the other hand, it is presumed that a portion where a clear periodic structure is not confirmed is mixed with amorphous or very fine crystal particles.
In sample numbers 1 and 3-17, both a clear lattice image and a periodic structure were not observed.
Sample No. 18 was not confirmed to have a clear lattice image, and was confirmed to be amorphous SiC from a limited field diffraction image.

FIG. 3 shows microscopic electron beam diffraction inside the particle in which the lattice image of the hard film of sample number 2 was confirmed. Spots are most clearly observed on the (002) hexagonal crystal plane. Also from this result, it is confirmed that the structure of the SiC film of the present invention contains SiC having a hexagonal crystal structure phase.
Similarly, in Sample Nos. 1 and 3 to 17, in the portion of the lattice image, the clearest spot was confirmed on the (002) hexagonal crystal plane.

<Hardness measurement of hard coating>
The hardness of the hard coating was measured using an Elionix nanoindentation device. In order to measure the hardness of the film, the specimen was tilted by 5 degrees, and after mirror polishing, a region where the maximum indentation depth was less than about 1/10 of the layer thickness within the polished surface of the film was selected. At this time, there was no influence of the base material even at about 1/5. 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 measurement method is easily influenced by the fine shape of the indenter, the temperature, humidity at the time of measurement, and the surface condition of the sample, and the obtained numerical values do not necessarily match the Vickers hardness. Therefore, single crystal Si as a standard sample was measured. The film hardness of the single crystal Si at that time is 12 GPa, and a relative comparison can be made based on this measurement result. Table 3 shows the measurement results.

<Friction coefficient measurement>
In order to measure the friction coefficient of the SiC film against the Fe-based material, a ball-on-disk wear test was performed under the following conditions, and the average friction coefficient was measured. Table 3 shows the measurement results.
Ball: Φ6 mirror finish, Material: SUJ2 (60HRC)
Base material: φ20 mirror finish, various coatings Turning radius: 3mm
Rotation speed: 10cm / s
Load: 2N
Sliding distance: 100m
Sliding environment: Room temperature, no lubrication

<Cutting test>
For durability evaluation with a cutting tool, made of ultrafine particle cemented carbide (WC-Co-VC-Cr, WC average particle size: 0.4 μm, Co content: 6% by weight, VC content: 0.2% by weight , Cr content 0.6 wt%) using a two-blade ball end mill base material with a radius of 0.5 mm, film formation was performed under the same conditions as described above. 1 to 18 coated tools were produced.

In addition, a single film of TiAlN film generally used in the market was prepared by the following procedure, and the characteristics with the SiC film were compared.
For coating of TiAlN, an arc ion plating apparatus (manufactured by Kobe Steel: AIP-S40) was used as a film forming apparatus. First, the substrate temperature is set to 500 ° C., and heating is performed for 60 minutes with a heater in the film forming apparatus. After the pressure in the vacuum container (chamber) reaches 4 × 10 ⁻³ Pa, Ar gas Was introduced into the vacuum vessel, and the pressure in the furnace was set to 2 Pa. Then, a DC bias voltage of −200 V was applied to the substrate, and the substrate was cleaned with Ar ions for 10 minutes. Thereafter, the pressure in the container was evacuated to 1 × 10 ⁻³ Pa, the temperature of the substrate was kept constant at 500 ° C., and N ₂ gas was introduced so that the pressure in the container was 2 Pa. Then, the bias voltage was set to −40 V, 150 A power was supplied to the arc evaporation source, and a TiAlN single film having a thickness of about 4 μm was formed.

The coated ball end mills of sample numbers 1 to 19 were evaluated for durability under the following evaluation conditions. The evaluation results are shown in Table 3.
[Cutting conditions]
Work material: Martensitic stainless steel (HRC52)
Tool rotation speed: 150,000 rotations / minute Table feed rate: 4500 m / minute Cutting depth: 0.05 mm in the axial direction, 0.2 mm pick feed
Machining method: 90 degree gradient surface machining (maximum axial depth of cut: 0.25 mm)
Coolant: Dry type Life judgment: Cutting length until maximum wear width reaches 0.1mm, rounded down to less than 10m

  The SiC films of Sample Nos. 1 to 17 formed with the SiC composite target have a hexagonal crystal structure phase, and have a higher hardness than Sample No. 18 which was amorphous SiC formed with an ordinary SiC target. there were.

  Sample Nos. 1 to 17 of the present invention example formed with a SiC composite target had a lower friction coefficient than Sample No. 18 formed with a normal SiC target. This is because a lot of C atoms having excellent lubricating performance are contained in the film.

Sample Nos. 1 to 13 which are examples of the present invention use different targets on the base film side and the hard film side of the intermediate film, and have a cubic crystal structure phase on the base material side and a hexagonal crystal structure on the hard film side. It was a structure containing a phase.
The intermediate film of Sample No. 14 was amorphous on the hard film side with a large content of Al and Si.
The intermediate film of Sample No. 15 used the same Al60Cr37Si3 target on the substrate side and the hard film side, and the entire intermediate film had a cubic crystal structure.
The intermediate film of Sample No. 17 used the same Al80V20 target on the base material side and the hard film side, and the entire intermediate film had a hexagonal crystal structure.

Sample Nos. 1 to 13 which are examples of the present invention have excellent adhesion because the hard film is a crystalline SiC film, the base material side of the intermediate film is a cubic crystal structure, and the hard film side is a hexagonal crystal structure. The tool life was further improved as compared with Sample Nos. 14 to 17 in which the intermediate film was different from the present invention.
Sample Nos. 1 to 13 of the present invention examples are excellent in sliding characteristics because of the large C content in the SiC film, and in particular, the welded material on the cutting edge surface is reduced and the cutting resistance is low. Moreover, it is presumed that it has excellent durability because of its high hardness and excellent heat resistance. Sample Nos. 1 to 13 of the present invention all showed cutting performance superior to Sample No. 18 which is a TiAlN film.
Among the hard coatings of the present invention example, from the comparison of sample numbers 1 to 3 where the intermediate coating is the same, the Si content in the SiC coating is large, and the hard coatings of sample numbers 1 and 2 having higher hardness are superior in cutting performance. showed that.
From comparison of Sample Nos. 2 and 13, the tool performance was better when the intermediate coating had the composition gradient layer.
In addition, the cutting performance tended to be superior when the crystal grain size of the intermediate coating on the hard coating side was approximately the same as the crystal grain size of the hard coating.
Sample No. 18 in which the hard coating was amorphous was considered to have insufficient sliding characteristics due to rapid progress of wear and strong adhesion of the mating material, and abnormal wear occurred.

  The present invention describes a coated tool used in applications requiring excellent wear resistance and sliding characteristics, such as a cutting tool or a die, and a method for manufacturing the same. In view of the excellent wear resistance and sliding characteristics, excellent durability can be exhibited even when applied to a member such as an automobile part.

Claims (12)

  A coated tool in which a hard film is coated on the surface of a base material of the tool via an intermediate film, and the hard film is a SiC film containing more C than Si in an atomic ratio and containing a hexagonal crystal structure phase in the structure. The intermediate film is a nitride or carbonitride composed of AlxMy (where x and y indicate atomic ratios, x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, where M is At least one selected from Ti, Cr, V, and Nb), the base material side has a cubic crystal structure, and the hard film side has a hexagonal crystal structure. Excellent coating tool.   2. The coated tool having excellent wear resistance and sliding properties according to claim 1, wherein the intermediate film has an Al content increasing from the substrate side toward the hard film side.   3. The coated tool having excellent wear resistance and sliding characteristics according to claim 1, wherein the intermediate film contains at least one selected from Si, Y, and B in an atomic ratio of 20% or less.   4. The coated tool having excellent wear resistance and sliding properties according to claim 3, wherein the intermediate film contains at least Si, and the Si content increases from the base material side toward the hard film side.   The coated tool excellent in wear resistance and sliding characteristics according to any one of claims 1 to 4, wherein the hard coating has a C content of 70% or less in terms of atomic ratio.   The coated tool excellent in wear resistance and sliding characteristics according to any one of claims 1 to 5, wherein the structure of the hard film is amorphous and contains a hexagonal crystal structure phase.   7. The structure of the hard film according to claim 1, wherein a hexagonal crystal plane of (101) or (002) shows a maximum strength in electron beam diffraction by a transmission electron microscope. A coated tool with excellent wear resistance and sliding properties. A manufacturing method in which a hard film is coated on a substrate surface of a tool via an intermediate film by a physical vapor deposition method, and the intermediate film is made of AlxMy (where x and y indicate atomic ratios, and x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, M is one or more selected from Ti, Cr, V, and Nb) using a plurality of targets having different compositions,
Nitride or carbonitride composed of AlxMy (where x and y are atomic ratios, x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, M is Ti, Cr, V, Nb 1 or more selected from the above), the base material side is formed in a cubic crystal structure, and the hard film side is formed in a hexagonal crystal structure,
The hard coating is characterized by using a SiC composite target containing a C phase of more than 0 and less than 25% by volume, and sputtering with an average power applied to the SiC composite target of 2 kW or more. Method of coated tools with excellent workability and sliding properties.   In the coating of the intermediate film, the Al content increases from the base material side toward the hard film side by increasing the power applied to the target having a high Al content among the multiple targets. The method for producing a coated tool having excellent wear resistance and sliding properties according to claim 8, wherein the coated tool is coated as described above.   In the coating of the intermediate film, AlxMy (where x and y indicate atomic ratios, x + y = 100, 40 ≦ x ≦ 95, and 5 ≦ y ≦ 60, and M is selected from Ti, Cr, V, and Nb. 1 or more), and further comprising at least one target containing 20% or less by atomic ratio of one or more selected from Si, Y, and B. A method for producing a coated tool having excellent wear resistance and sliding properties as described.   In the coating of the intermediate film, at least one target containing Si is used, and by increasing the power applied to the target containing Si, the content of Si from the substrate side toward the hard film side The method for manufacturing a coated tool having excellent wear resistance and sliding properties according to claim 10, wherein the coating is performed so that the resistance increases.   The method for producing a coated tool having excellent wear resistance and sliding properties according to any one of claims 8 to 11, wherein the C phase of the SiC composite target is 2% or more by volume ratio.