WO2014157688A1

WO2014157688A1 - Coated cutting tool and method for producing same

Info

Publication number: WO2014157688A1
Application number: PCT/JP2014/059331
Authority: WO
Inventors: 佳奈森下; 亮太郎府玻; 秀峰小関; 福永　有三; 久保田　和幸; 謙一井上
Original assignee: 日立ツール株式会社
Priority date: 2013-03-28
Filing date: 2014-03-28
Publication date: 2014-10-02
Also published as: JP5673904B1; JPWO2014157688A1

Abstract

The present invention provides a coated cutting tool that has: a substrate; an intermediate coating film comprising a carbide containing tungsten (W) and titanium (Ti) and having a film thickness of 1-10 nm; and a hard coating film comprising an AlTi-based nitride or carbonitride having a crystal structure that is a face-centered cubic lattice structure, and having an Al content (atom%) of at least 60% and a Ti content (atom%) of at least 20%. Of the hard coating film, in a strength profile according to a selected area diffraction pattern in a transmission electron microscope, when the peak strength caused by the AlN (010) plane of a hexagonal closest packing structure is Ih, and the total of the peak strength caused by the AlN (111) plane, the TiN (111) plane, the AlN (002) plane, the TiN (002) plane, the AlN (022) plane and the TiN (022) plane in the face-centered cubic lattice structure and the peak strength caused by the AlN (010) plane, the AlN (011) plane, and the AlN (110) plane in the hexagonal closest packing structure is Is, Ih×100/Is ≤ 20.

Description

Coated cutting tool and manufacturing method thereof

The present invention relates to a coated cutting tool suitable for application to, for example, cutting of steel, cast iron, heat-resistant alloy, and the like, and a manufacturing method thereof.

Conventionally, for the purpose of improving the durability of a cutting tool, a surface treatment for coating the surface of the tool with a hard film has been performed. Among hard coatings, a composite nitride coating of Al and Ti (hereinafter referred to as AlTiN) is widely applied because of its excellent wear resistance. Usually, AlTiN tends to have higher heat resistance when the Al content is high. However, it is known that when the Al content is too high, brittle hcp-structured AlN precipitates and the hardness decreases. For example, Patent Document 1 discloses that the hardness of AlTiN starts to decrease when the Al content ratio (atomic%) of metal (including metalloid) elements is 60% or more. When the content ratio (atomic%) is 70%, the hcp structure is confirmed as part of the crystal structure.

On the other hand, Patent Document 2 proposes a coating method of an AlTi nitride film in which the fcc structure is easily maintained even when the Al content is large. In Patent Document 2, a cathode in which a permanent magnet is disposed laterally or in front is used, and a magnetic field line that diverges forward or travels substantially in front of the target evaporation surface is formed, thereby forming a film forming gas in the vicinity of the object to be processed. It is disclosed that the plasma density is significantly higher than that of a conventional cathode. By covering with such a cathode, even if it is an AlTi-based nitride film in which the Al content (atomic%) of metal (including metalloid) elements exceeds 70%, the fcc structure is mainly used. Is disclosed.

JP-A-8-209333 JP 2003-71610 A

In recent years, the working environment of cutting tools has become more severe due to the high hardness and high speed machining of workpieces. For example, when machining a high hardness material such as tempered cold tool steel, in severe environments such as roughing, film peeling of the tool and progress of tool wear are likely to occur at an early stage. It was confirmed that satisfactory durability could not be obtained even when a coated cutting tool such as that disclosed in Patent Literature was applied.

The present invention has been made in view of the above circumstances. An object of this invention is to provide the coated cutting tool excellent in durability, and its manufacturing method.

The inventors of the present invention have used AlN having a hexagonal close-packed (hcp; hereinafter simply abbreviated as “hcp”) structure contained in the microstructure of a hard film made of an AlTi-based nitride or carbonitride. We found the optimal tissue morphology that was reduced. And, by providing a special intermediate film between the base material and the hard film, it was confirmed that the effect of the hard film was sufficiently exhibited, and excellent durability was exhibited even at high speed processing of high hardness materials. The present invention has been reached.

That is, this invention is a coated cutting tool which coat | covered the hard film | membrane on the surface of the base material (cutting tool). Specifically, a base material, an intermediate film disposed on the base material and made of carbide containing tungsten (W) and titanium (Ti) and having a thickness of 1 nm or more and 10 nm or less, and on the intermediate film The crystal structure arranged and specified by X-ray diffraction is a face-centered cubic lattice (fcc; hereinafter simply abbreviated as “fcc”) structure, and is based on the total amount of metal (including metalloid) elements A hard film made of an AlTi-based nitride or carbonitride having an Al content ratio (atomic%) of 60% or more and a Ti content ratio (atomic%) of 20% or more,
The hard coating is a coated cutting tool that satisfies a relationship of “Ih × 100 / Is ≦ 20” in an intensity profile obtained from a limited field diffraction pattern of a transmission electron microscope. Preferably, “Ih × 100 / Is ≦ 15”.
Ih = peak intensity due to AlN (010) plane of hcp structure Is = fcc structure of AlN (111) plane, TiN (111) plane, AlN (002) plane, TiN (002) plane, AlN (022) plane And the peak intensity due to the TiN (022) plane and the peak intensity due to the AlN (010) plane, the AlN (011) plane, and the AlN (110) plane of the hcp structure The hard coating has an Al content ratio (atomic%) of 62% to 70% and a Ti content ratio (atomic%) of 25% or more with respect to the total amount of metal (including metalloid) elements. In addition, it is preferable that the total content ratio (atomic%) of Al and Ti is 90% or more with respect to the total amount of metal (including metalloid) elements.

Furthermore, the film thickness of the intermediate film is preferably 1 nm or more and less than 6 nm. Furthermore, it is preferable that the half width of the (200) plane of the fcc structure specified by X-ray diffraction is 1.8 ° or less.
Moreover, it is preferable that in the intensity | strength profile calculated | required from the restriction | limiting field-of-view diffraction pattern of the film | membrane cross section by a transmission electron microscope, the hard film shows the peak intensity | strength resulting from the same crystal plane on the base material side and the surface side. In the intensity profile obtained from the limited field diffraction pattern, the peak intensity attributed to the same crystal plane is more preferably the peak intensity attributed to the AlN (002) plane and TiN (002) plane of the fcc structure.
Furthermore, the hard coating preferably contains tungsten (W), and the content ratio (atomic%) of W is 1% or more and 10% or less with respect to the total amount of metal (including metalloid) elements. preferable. Further, the W content (atomic%) is preferably 2% or more and 6% or less.
The film thickness of the hard coating is preferably 1 μm or more and 5 μm or less.
The cutting tool serving as the substrate is preferably a radius end mill or a square end mill.

Moreover, the coated cutting tool of this invention is suitably manufactured with the manufacturing method of the coated cutting tool of this invention shown below. In particular,
The surface of the base material is subjected to metal bombardment to form an intermediate film having a thickness of 1 nm to 10 nm made of carbide containing tungsten (W) and titanium (Ti) on the surface of the base material; Using a cathode having a magnetic flux density of 18 mT or more, applying a bias voltage of −200 V or more and −70 V or less to the base material, and with respect to the total amount of metal (including metalloid) elements on the intermediate film, Forms a hard coating made of AlTi nitride or carbonitride with aluminum (Al) content (atomic%) of 60% or more and titanium (Ti) content (atomic%) of 20% or more And a method of manufacturing a coated cutting tool.
Furthermore, it is preferable that the hard film is formed at a substrate temperature of 450 ° C. or higher and 580 ° C. or lower. Furthermore, the heating temperature of the base material before the metal bombardment treatment is preferably 500 ° C. or less.
Furthermore, it is preferable that the hard film further contains tungsten (W). Further, the hard coating preferably has a tungsten (W) content ratio (atomic%) of 1% or more and 10 or less% with respect to the total amount of metal (including metalloid) elements. Furthermore, it is preferable that the content ratio (atomic%) of the tungsten (W) is 2% or more and 6% or less.
Furthermore, it is preferable that the manufacturing method of the said coated tool is applied to a radius end mill or a square end mill.

ADVANTAGE OF THE INVENTION According to this invention, the coated cutting tool excellent in durability and its manufacturing method are provided.
That is, according to the present invention, in addition to high-speed machining of a high-hardness material, excellent durability is exhibited also in cutting of high-carbon steel, Ni-base superalloy, and the like.

FIG. 1 is a cross-sectional observation photograph of a hard film with a transmission electron microscope (the circumferential portion in the figure is an electron beam irradiation position when a limited field diffraction pattern is photographed). FIG. 2 is a diagram showing a limited field diffraction pattern when an electron beam is irradiated within the lower circumference of FIG. FIG. 3 is a diagram showing an intensity profile of the limited field diffraction pattern shown in FIG. FIG. 4 is a cross-sectional observation photograph of the sample tool of Example 1 of the present invention using a transmission electron microscope. FIG. 5 is a diagram showing a nanobeam diffraction pattern at a point indicated by an arrow 1 in FIG. FIG. 6 is a diagram showing an EDS spectrum analysis result at a point indicated by an arrow 1 in FIG. FIG. 7 is a diagram showing a nanobeam diffraction pattern at a point indicated by an arrow 2 in FIG. FIG. 8 is a diagram showing an EDS spectrum analysis result at a point indicated by an arrow 2 in FIG. FIG. 9 is a diagram showing an EDS spectrum analysis result at a point indicated by an arrow 3 in FIG. FIG. 10 is an observation photograph of the cutting edge of the sample tool of Examples 1 to 5 of the present invention after cutting 25 m with an electron microscope. FIG. 11 is an observation photograph of the tool edge of the sample tools of Examples 6 to 8 of the present invention after 25 m cutting with an electron microscope. FIG. 12 is an observation photograph of the tool edge of the sample tools of Comparative Examples 1 to 6 after 25 m cutting with an electron microscope. FIG. 13 is an observation photograph of the tool edge of the sample tools of Comparative Examples 7 to 10 after 25 m cutting with an electron microscope. FIG. 14 is an observation photograph of the tool cutting edge of the sample tools of Invention Examples 20 to 23 and Comparative Example 20 after 4 m cutting with an electron microscope.

The inventors of the present invention can analyze only the peak intensity of the fcc structure (face-centered cubic lattice structure) in X-ray diffraction, even if it is a nitride or carbonitride containing Al and Ti, and is analyzed with a transmission electron microscope. It was confirmed that the microstructure contained AlN having an hcp structure. And it turned out that a favorable characteristic as a hard film is acquired by reducing AlN of the hcp structure (hexagonal close-packed structure) contained in a microstructure.
Furthermore, it has been found that the durability of the coated cutting tool can be improved by providing an intermediate film having a specific composition and film thickness between the substrate and the hard film.
Hereinafter, the coated cutting tool of the present invention and the manufacturing method thereof will be described in detail.

First, the hard film of the present invention will be described.
The hard film is a nitride or carbonitride which is a film type having excellent heat resistance and wear resistance. More preferred is nitride.
Al is an element that imparts heat resistance to the hard coating. By containing the most Al content (atomic%) among metal (including metalloid) elements, it exhibits excellent heat resistance and is coated. The durability of the cutting tool is improved. In order to impart excellent heat resistance to the hard coating, the Al content (atomic%) of the metal (including metalloid) elements is set to 60% or more. A more preferable Al content ratio (atomic%) is 62% or more, and further 65% or more with respect to the total amount of metal (including metalloid) elements.
In order to impart high durability to the coated cutting tool, the Al content ratio (atomic%) is preferably 75% or less with respect to the total amount of metal (including metalloid) elements. A more preferable Al content ratio (atomic%) is 70% or less with respect to the total amount of metal (including metalloid) elements.

Ti is an important element in that it imparts wear resistance to the hard coating and has a fcc structure crystal structure with excellent durability as a coated cutting tool. When the Ti content decreases, the wear resistance of the hard coating decreases, and the hcp structure AlN increases as the peak intensity of the hcp structure is confirmed by X-ray diffraction. In order to provide wear resistance and an fcc crystal structure, in addition to defining the Al content, the Ti content (atomic%) is set to the total amount of metal (including metalloid) elements. 20% or more. Furthermore, the Ti content ratio (atomic%) is more preferably 25% or more.
In the present invention, the nitride or carbonitride containing Al and Ti has a total content ratio (atomic%) of Al and Ti of metal (including metalloid) from the viewpoint of heat resistance and wear resistance. It is preferable to set it as 90% or more with respect to the total amount of an element.

In the present invention, the crystal structure specified by X-ray diffraction is an fcc structure, for example, when measured using a commercially available X-ray diffractometer (RINT2500V-PSRC / MDG manufactured by Rigaku Corporation). It means that the peak intensity due to the hcp structure is not confirmed.

In the present invention, in order to quantify the AlN content of the hcp structure contained in the microstructure of the hard film, an intensity profile obtained from a limited field diffraction pattern of a transmission electron microscope (hereinafter referred to as TEM) was used. . The measurement method will be described below. In order to unify the measurement conditions, the acceleration voltage: 120 V, the limited visual field region: φ750 nm, the camera length: 100 cm, the incident electron quantity: 5.0 pA / cm ² (on the fluorescent plate), the substrate side and the surface side of each sample The limited field diffraction pattern was obtained.

In FIG. 1, the cross-sectional TEM observation photograph (40,000 times) of a hard film is shown. FIG. 2 is a limited field diffraction pattern of the lower circle part of FIG. Then, the intensity of the limited field diffraction pattern of FIG. 3 was obtained by converting the luminance of the limited field diffraction pattern of FIG. In FIG. 3, the horizontal axis represents the distance (radius r) from the center of the (000) plane spot, and the vertical axis represents the integrated intensity (arbitrary unit) for one circle around each radius r.
In FIG. 3, an arrow 1 is a peak due to the AlN (010) plane of the hcp structure, and is the maximum intensity of AlN of the hcp structure. Arrow 2 is a peak due to the AlN (011) plane of the hcp structure, the AlN (111) plane of the fcc structure, and the TiN (111) plane. Arrow 3 is a peak due to the AlN (002) plane and TiN (002) plane of the fcc structure. The arrow 4 is a peak due to the AlN (110) plane of the hcp structure. An arrow 5 is a peak due to the AlN (022) plane and TiN (022) plane of the fcc structure.

The inventors of the present invention have made a ratio (%) between the sum of peak intensities (Is) indicated by arrows 1 to 5 in FIG. 3 and the peak intensity (Ih) attributed to the AlN (010) plane, which is the maximum intensity of the hcp structure. It has been found that by calculating Ih × 100 / Is), AlN having an hcp structure contained in the hard coating can be quantitatively evaluated.
Therefore, in the present invention, the peak intensity due to the AlN (010) plane of the hcp structure is Ih, and the AlN (111) plane, TiN (111) plane, AlN (002) plane, TiN (002) plane of the fcc structure, The sum of the peak intensity attributed to the AlN (022) plane and the TiN (022) plane and the peak intensity attributed to the AlN (010) plane, (011) plane, and (110) plane of the hcp structure is defined as Is. In this case, it is assumed that the relationship “Ih × 100 / Is ≦ 20” is satisfied. When this relationship was satisfied, it was confirmed that the hcp-structured AlN contained in the hard film was small and the durability of the coated cutting tool was excellent. Among them, more preferably, the case where the relationship of “Ih × 100 / Is ≦ 15” is satisfied, and still more preferably, the case where the relationship of “Ih × 100 / Is ≦ 13” is satisfied. In order to eliminate the error due to the setting method, the background value was evaluated without removing it.
In the fcc structure, the (002) plane and the (200) plane are equivalent, and the (022) plane and the (220) plane are equivalent. In the TEM analysis of the present invention, the (111) plane, (002) plane, and (022) plane are shown as representative of the equivalent crystal plane of the fcc structure.

In the intensity profile obtained from the limited field diffraction pattern of the transmission electron microscope, it is preferable that the peak intensity due to the same crystal plane on the substrate side and the surface side shows the maximum intensity of the hard film in the present invention. In addition to controlling “Ih × 100 / Is” to be constant, the entire hard film is continuous and uniform by making the crystal face showing the maximum strength the same on the substrate side and the surface side of the hard film. And the durability of the coated cutting tool is improved. In particular, the peak strength due to the AlN (002) surface and TiN (002) surface of the fcc structure is maximized on the base material side and the surface side of the hard coating, which is preferable because durability tends to be improved. .

If the hard coating becomes too thin, the excellent durability may not be fully exhibited. In addition, when the hard film becomes too thick, film peeling may occur. For the thickness of the hard coating, an appropriate value may be selected from a range of 0.5 μm to 10 μm, for example. The thickness of the hard film is more preferably 1 μm or more. Furthermore, the thickness of the hard coating is more preferably 2 μm or more. Further, the thickness of the hard film is more preferably 5 μm or less.

Next, the intermediate film will be described.
As described above, in order to maximize the effect of the hard coating using AlTi nitride or carbonitride with reduced hcp-structured AlN contained in the microstructure, It is important to provide a special intermediate film between the film. The present inventors have intensively studied, and by providing an intermediate film made of carbide containing W and Ti on the base material, not only the adhesion between the base material and the hard film is improved, but also included in the hard film. It was confirmed that the AlN having a hcp structure was reduced and the durability of the coated cutting tool was improved.

If the intermediate film immediately above the base material is a carbide containing W, it is considered that the affinity with the cemented carbide, which is the base material, becomes strong and the adhesiveness is excellent. In addition, when Ti is included in the intermediate film, since the carbide of Ti has an fcc structure, the hard film immediately above the intermediate film grows starting from the carbide of Ti, so that the AlN having an hcp structure included in the hard film. Is considered to be reduced.
Moreover, even if the film thickness of the intermediate film is too thin or too thick, it is not preferable for improving the adhesion to the substrate. Therefore, the film thickness of the intermediate film is in the range of 1 nm to 10 nm. The lower limit of the thickness of the intermediate film is preferably 2 nm or more, and more preferably 3 nm or more. Further, the upper limit of the film thickness of the intermediate film is preferably less than 6 nm.

The intermediate film may contain a film component and a base material component in addition to W and Ti. The intermediate film can contain Co on the base material side and Al or N on the hard film side, but the effect of the present invention is exhibited by using carbide containing W and Ti. The presence of the intermediate film can be confirmed by cross-sectional observation by transmission electron microscope observation, composition analysis, and nanobeam diffraction pattern.

If the structure of the hard coating becomes too fine, crater wear tends to increase. The refinement of the structure of the hard coating is reflected in the half width (unit: °; full width at half maximum). Therefore, when the value of the half width increases, the film structure tends to become fine, and when the value of the half width decreases, the film structure tends to become coarse. In order to improve the crater wear resistance of the hard coating in the present invention, it is preferable that the half width of the (200) plane of the fcc structure specified by X-ray diffraction is 1.8 ° or less. When the half width value is larger than 1.8 °, the film structure becomes too fine, and the crater wear resistance may decrease.

The hard coating in the present invention is one or more selected from the group consisting of metal elements of Group 4a (excluding Ti), Group 5a, Group 6a (excluding Cr), Si and B of the periodic table. The element can be contained in a content ratio (atomic%) of metal (including metalloid) elements of 0% or more and 15% or less. These elements are generally elements added to the hard coating, and do not reduce the durability of the coated cutting tool of the present invention as long as the content ratio is not excessive.
Further, according to the study by the present inventors, it has been confirmed that depending on the work material and the processing conditions, the hard coating may further contain the above-described elements, thereby exhibiting superior durability. This is presumably because AlTi-based nitrides or carbonitrides contain other metal (semi-metal) elements to improve heat resistance and toughness. However, if the content of the additive element is too large, the wear resistance and heat resistance of the hard coating tend to be lowered. Therefore, even when added, the content ratio (atomic%) of metal (including metalloid) elements is preferably less than 15%.

The hard film in the present invention contains W (tungsten), so that the compressive residual stress of the film can be reduced while maintaining high hardness. According to the study by the present inventors, when the hard coating contains W, superior durability is easily exhibited not only in high-hardness materials but also in cutting of high-carbon steel and Ni-base superalloys. . In order to achieve better durability for a wide range of work materials, the hard coating has a W content (atomic%) of 1% relative to the total amount of metal (including metalloid) elements. It is more preferably 10% or less and more preferably 2% or more and 6% or less.

The composition of the hard film after coating may be different from the target composition. The composition of the hard film in the present invention can be confirmed, for example, by using a wavelength dispersion type electron probe microanalysis (WDS-EPMA).

In the present invention, another layer may be coated on the hard film made of an AlTi-based nitride or carbonitride in order to exhibit the effects of the present invention. Therefore, in the present invention, the film structure having the intermediate film made of carbide containing W and Ti and the hard film made of AlTi nitride or carbonitride is made of AlTi nitride or carbonitride. In addition to the hard film being the outermost surface of the tool, another layer may be coated. In this case, another hard film made of nitride or carbonitride having excellent heat resistance and wear resistance is coated on the hard film made of AlTi nitride or carbonitride as a protective film. Preferably it is. More preferably, the protective film is a layer made of nitride.

Next, the coating method of the hard film of this invention is demonstrated.
The inventors of the present invention have confirmed that the magnetic field of the cathode used for coating the hard film affects the amount of AlN of the hcp structure contained in the microstructure of the AlTi nitride or carbonitride. Then, for example, by arranging permanent magnets on the outer periphery and back surface of the target, and covering the hard film with a cathode having a magnetic flux density of 18 mT or more near the center of the target, the AlN having an hcp structure contained in the microstructure It was confirmed that the amount decreased and the durability of the coated cutting tool improved. More preferably, the magnetic flux density near the center of the target is 20 mT or more.
However, if the negative bias voltage applied to the base material during the coating of the hard film is larger than −70 V (positive side with respect to −70 V), the amount of AlN in the hcp structure tends to increase. Therefore, the negative bias voltage applied to the base material during the coating of the hard film is preferably in the range of −200 V to −70 V, more preferably in the range of −150 V to −100 V.

When forming a hard film, the film structure tends to be coarse when the film formation temperature is low. However, if the film forming temperature of the hard film becomes too low, the compressive residual stress of the film becomes too high and the film tends to be self-destructed. Therefore, it is preferable that the hard film is formed at a substrate temperature of 450 ° C. or higher. On the other hand, when the film formation temperature of the hard film increases, the film structure tends to become finer. However, if the film formation temperature of the hard film becomes too high, the residual stress applied to the hard film is lowered, the hard film is softened, and the wear resistance is likely to be lowered. Therefore, it is preferable to form the hard film at a substrate temperature of 580 ° C. or lower.
However, even if the film forming temperature of the hard film is controlled within a preferable range, if the heating temperature of the base material before the bombarding process is high, the peak due to the different crystal planes on the base side and the surface side of the hard film Intensity may indicate maximum intensity. For this reason, the heating temperature of the base material before the bombardment treatment is preferably 500 ° C. or less. Moreover, it is preferable to coat | cover a hard film | membrane by adjusting the nitrogen gas flow rate introduce | transduced in a furnace at the time of coating | coated of a hard film | membrane, and the pressure in a furnace 4 Pa or less 6 Pa.

Then, the manufacturing method of an intermediate film is demonstrated.
In order to form a carbide containing W and Ti on the substrate, a cathode having a magnetic field configuration in which a coil magnet is arranged on the outer periphery of the target to confine the arc spot inside the target, and Ti is used as a metal bombardment. It is preferred to perform bombardment. By bombarding with Ti, which is an element species that easily forms carbides, using such a cathode, the oxide on the substrate surface is removed and cleaned, and the bombarded Ti ions are removed from the substrate surface. Carbides containing W and Ti are easily formed by diffusing into WC.
Further, when Ti bombardment is performed, if a negative bias voltage applied to the substrate and a current applied to the target are low, carbides containing W and Ti are difficult to be formed. Therefore, the negative bias voltage applied to the substrate is preferably −1000 V or more and −700 V or less. Further, the current supplied to the target is preferably 80 A or more and 150 A or less. Moreover, since the carbide | carbonized_material containing W and Ti will become difficult to be formed when the heating temperature of the base material before a bombard process becomes low, it exists in the tendency for the adhesiveness of a base material and a hard film to fall. Therefore, it is preferable that the heating temperature of the substrate is set to 450 ° C. or higher and the subsequent bombardment treatment is performed.
Ti bombardment may be carried out while introducing argon gas, nitrogen gas, hydrogen gas, hydrocarbon-based gas, etc., but it can be performed by carrying out the furnace atmosphere under a vacuum of 1.0 × 10 ⁻² Pa or less. The material surface is preferably cleaned and the diffusion layer is easily formed.

The coated cutting tool of the present invention is particularly effective when applied to a radius end mill or a square end mill that mainly uses an outer peripheral blade.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

(Example 1)
<Base material>
As a base material, the composition is WC (bal.)-Co (8 mass%)-TaC (0.25 mass%)-Cr ₃ C ₂ (0.9 mass%). An insert type radius end mill made of cemented carbide having a hardness of 6 μm and a hardness of 93.4 HRA was prepared.
Note that WC represents tungsten carbide, Co represents a cobalt atom, and TaC represents tantalum carbide.

<Deposition system>
For film formation, an arc ion plating type film forming apparatus was used.
The inside of the vacuum vessel provided in the film forming apparatus is evacuated by a vacuum pump, and then gas is introduced from a supply port. Each base material installed in the vacuum vessel is electrically connected to a bias power source, and a negative DC bias voltage can be independently applied to each base material.
A base material rotating mechanism for rotating the base material is provided in the vacuum vessel. This base material rotating mechanism includes a planetary, a plate-like jig arranged on the planetary, and a pipe-like jig arranged on the plate-like jig, and the planetary rotates at a speed of 3 revolutions per minute. And the plate-like jig and the pipe-like jig revolve each other.

When the substrate was coated with a hard film, a permanent magnet was provided on the outer periphery and the rear surface of the target, and a cathode (hereinafter referred to as C1) that generates an average magnetic flux density of 20.2 mT was used.
Here, in Comparative Example 2, a permanent magnet was provided on the back surface, and a cathode (hereinafter referred to as C2) having an average magnetic flux density of 15.1 mT was used.
Moreover, when performing metal bombardment processing, the cathode (henceforth C3) which provided the coil magnet on the outer periphery of the target was used.

<Film formation process>
The inside of the vacuum vessel was evacuated to 8 × 10 ⁻³ Pa or less. Then, the base material was heated with the heater installed in the vacuum vessel, and evacuation was performed. The heating temperature of the base material was changed for each sample tool. The pressure inside the vacuum vessel was set to 8 × 10 ⁻³ Pa or less. Thereafter, cleaning with Ar plasma was performed, and subsequently, Ti bombarding was performed as metal bombarding to form an intermediate film. Next, the gas in the vacuum vessel was replaced with nitrogen, and the pressure in the vacuum vessel was set to 5 Pa. The film forming temperature and the bias voltage were changed, a current of 150 A was supplied to the cathode, and a hard film having a thickness of about 2 μm was coated on the surface of the base material.
As described above, a coated cutting tool (sample tool) in which the surface of the base material was coated with the intermediate film and the hard film was produced.
Except for Comparative Example 1, before the hard coating was applied, vacuum evacuation was performed to 8 × 10 ⁻³ Pa or less, an arc current of 150 A was supplied to C3, and Ti bombarding was performed.
In Comparative Examples 1, 8, and 9, films were formed as follows.
In Comparative Example 1, the hard coating was applied without metal bombardment after cleaning with Ar plasma.
In Comparative Example 8, after cleaning with Ar plasma, TiN was coated as an intermediate film without performing metal bombardment.
In Comparative Example 9, CrN was coated as an intermediate film without performing metal bombardment after cleaning with Ar plasma.

<Composition analysis>
The composition of the hard film of the sample tool was measured by wavelength dispersive electron probe microanalysis (WDS-EPMA) using an electronic probe microanalyzer device (model number: JXA-8500F) manufactured by JEOL Ltd. The composition was determined by measuring five points and averaging the measured values.
The measurement conditions were acceleration voltage: 10 kV, irradiation current: 5 × 10 ⁻⁸ A, capture time: 10 seconds, analysis area diameter: 1 μm, analysis depth: approximately 1 μm.

<Hardness measurement>
The hardness of the hard coating of the sample tool was measured using a nanoindentation device (model number: ENT-1100a) manufactured by Elionix Co., Ltd. In order to measure the hardness of the hard coating, the insert 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 polishing surface of the coating was selected. At this time, there was no influence of the base material even at about 1/5.
The hardness was measured at 10 points, and the average value of the measured values was determined as the hardness.
The measurement conditions were indentation load: 49 mN, maximum load holding time: 1 second, and removal speed after load application: 0.49 mN / second. Prior to the measurement, single crystal Si as a standard sample was measured, and it was confirmed that its hardness was 12 GPa.

<X-ray diffraction>
The crystal structure of the hard film of the sample tool was evaluated using X-ray diffraction. Specifically, using an X-ray diffractometer (model number: RINT2500V-PSRC / MDG) manufactured by Rigaku Corporation, tube voltage: 40 kV, tube current: 300 mA, X-ray source: Cukα (λ = 0.15418 nm), 2θ : It was carried out under measurement conditions of 30 ° to 70 °. And the half width was measured from the peak intensity of the (200) plane.

<TEM observation>
The cross section was observed with a transmission electron microscope (TEM), and the intermediate film or hard film of the sample tool was evaluated. Specifically, using a field emission transmission electron microscope (model number: JEM-2010F type) manufactured by JEOL Ltd., TEM analysis was performed under the conditions of acceleration voltage: 120 V and incident electron quantity: 5.0 pA / cm ^2. Carried out. The TEM analysis was performed by observing the cut surface when the intermediate film or the hard film was cut along a plane perpendicular to the film surface.
The limited field diffraction pattern was implemented with a camera length of 100 cm and a limited field region of φ750 nm. The peak intensities of the hcp structure and the fcc structure were obtained from the intensity profile obtained from the limited field diffraction pattern. For each sample, the limited field diffraction pattern was measured at two locations on the substrate side and the surface side of the hard coating.
The composition of the intermediate film was analyzed with a beam diameter of 1 nm using an attached UTW type Si (Li) semiconductor detector. Nanobeam diffraction was analyzed with a camera length of 50 cm and a beam diameter of 2 nm or less.
In addition, about the sample tool of the comparative example 3, since the Al content is a hard film with little Al, the TEM analysis of a hard film is not implemented. For the sample tools of Comparative Examples 4 and 10, since the peak intensity of the hcp structure is confirmed even by X-ray diffraction, the TEM analysis of the hard coating is not performed. About the sample tool of the comparative example 5, since the film | membrane type differs from the hard film of this invention, the TEM analysis of a hard film is not implemented.

FIG. 4 shows a transmission electron micrograph (2,000,000 times) of the sample tool of Example 1 of the present invention. In the figure, the point indicated by the arrow 1 is the base material, the point indicated by the arrow 2 is the intermediate film, and the point indicated by the arrow 3 is the hard film.
From the EDS spectrum analysis result of FIG. 6 and the nanobeam diffraction pattern of FIG. 5, it was confirmed that the arrow 1 in FIG. 4 is WC. From the EDS spectrum analysis result of FIG. 9, it was confirmed that the arrow 3 in FIG. 4 is a hard film. From the EDS spectrum analysis result of FIG. 8, it was confirmed that the intermediate film contains W and Ti. Further, it was possible to index the WC crystal structure from the nanobeam diffraction pattern of FIG. From the EDS spectrum analysis and the nanobeam diffraction pattern, it was confirmed that the intermediate film was a carbide containing W and Ti.
The intermediate film contained the largest amount of W in the content ratio (atomic%) of metal (including metalloid) elements, and then contained a large amount of Ti. In addition to W and Ti, Al and N, which are hard film components, were contained. Further, Co, which is a base material component, was also slightly contained.

<Cutting test>
A cutting test was performed with the work material as SKD11. Cutting conditions are as follows.
<Conditions for cutting test>
・ Tool: Insert type radius end mill for machining hard materials φ12 × R2 × 3 flute (manufactured by Hitachi Tool Co., Ltd.)
・ Cutter model number: ASRM-1012R-3-M6
-Insert model number: EPHN0402TN-2
・ Cutting method: Bottom cutting ・ Work material: SKD11 (60HRC)
・ Incision: axial direction 0.15mm, radial direction 6mm
・ Number of teeth: 1
・ Spindle speed: 1856min ^-1
・ Table feed: 742 mm / min
・ Single blade feed rate: 0.4mm / tooth
・ Cutting oil: Air blow ・ Cutting distance: 25 m

Table 2 shows the results of film characteristics.
FIG. 10 shows an observation photograph (100 times) of the cutting edge after the cutting test performed on the sample tools of Examples 1 to 5 of the present invention. FIG. 11 shows an observation photograph (100 times) of the cutting edge after the cutting test performed on the sample tools of Examples 6 to 8 of the present invention.
The sample tools of Examples 1 to 8 of the present invention had a higher Al content than the sample tool of Comparative Example 2, but it was confirmed that there was less hcp structure of AlN on the base material side and the surface side of the hard coating. All of the sample tools of the examples of the present invention were in a damaged state at a level that enables cutting following the cutting test.

From a comparison between the sample tool of Invention Example 1 and the sample tools of Invention Examples 4 and 8, the film thickness of the intermediate film is more excellent than the thickness of 2 nm among the preferable ranges of the film thickness of the intermediate film. It was confirmed that it showed high durability.
From the comparison of the sample tool of the present invention example 1 and the sample tool of the present invention example 5, even in the sample tool of the present invention example in which the film thickness of the intermediate coating film is in the preferred range, the same on the substrate side and the surface side of the hard coating film It was confirmed that the peak intensity resulting from the crystal plane showed the maximum strength with less film damage and better durability.
From a comparison between the sample tool of Invention Example 1 and the sample tool of Invention Example 6, it was confirmed that the smaller the value of “Ih × 100 / Is”, the better the durability. From a comparison between the sample tool of Invention Example 1 and the sample tool of Invention Example 7, it was confirmed that the smaller half width of the (200) plane shows superior durability.

In all of the comparative examples, the tool damage was large, and it was impossible to carry out subsequent cutting. FIG. 12 shows an observation photograph (100 times) of the cutting edge after a 25 m cutting test performed on the sample tools of Comparative Examples 1 to 6. FIG. 13 shows an observation photograph (100 times) of the cutting edge after a 25 m cutting test performed on the sample tools of Comparative Examples 7 to 10.
The sample tool of Comparative Example 1 has a small value of “Ih × 100 / Is” of the hard coating, but since the intermediate coating is not formed, the adhesion between the base material and the hard coating is not sufficient, and the tool damage is large. became.
Since the sample tool of Comparative Example 2 was coated with a hard film using a cathode having a smaller magnetic flux density near the target surface than the sample tool of the present invention example, the hcp structure AlN contained in the hard film increased. , Tool damage increased.
Since the sample tool of Comparative Example 3 has a small Al content contained in the hard coating, the tool damage was large.
In the sample tool of Comparative Example 4, since the bias voltage applied to the base material was small when the hard film was coated, the peak intensity due to the hcp-structured AlN was confirmed even by X-ray diffraction. As a result, tool damage increased.
In the sample tool of Comparative Example 5, since the AlCr-based nitride was formed on the hard coating, the tool damage increased.
Since the sample tool of Comparative Example 6 was subjected to a Ti bombardment process for a short time for the purpose of cleaning the base material, an intermediate film like the sample tool of the present invention example was not confirmed. For this reason, the adhesion between the base material and the hard film was insufficient, and the tool damage was increased.
In the sample tool of Comparative Example 7, the film thickness of the intermediate film became too thick, the adhesion between the base material and the hard film was not sufficient, and the tool damage increased.
Since the sample tool of Comparative Example 8 and the sample tool of Comparative Example 9 were provided with an intermediate film of nitride, the adhesion between the base material and the hard film was not sufficient, and the tool damage increased.
Since the sample tool of Comparative Example 10 has a small Ti content in the hard coating, the peak intensity due to AlN having the hcp structure was confirmed even by X-ray diffraction. As a result, tool damage increased.

(Example 2)
In Example 1, except that the film forming conditions in the film forming process were changed as shown in Table 3, the coated cutting in which the intermediate film and the hard film were coated on the surface of the substrate in the same manner as in Example 1 A tool (sample tool) was produced.
A cutting test was performed on the sample tools of Examples 20 to 23 of the present invention and Comparative Example 20 in order to confirm the effect of the additive element with S50C as the work material. Cutting conditions are as follows. The film formation conditions are shown in Table 3, and the physical properties of the sample tool thus produced are shown in Table 4, respectively.

<Conditions for cutting test>
・ Tool: High feed radius mill φ63 × 4 blades (Hitachi Tool Co., Ltd.)
・ Cutter model number: ASRT5063R4
-Insert model number: WDNW140520
-Cutting method: Bottom cutting-Work material: S50C (220HB)
・ Incision: 1.0mm in the axial direction, 42mm in the radial direction
・ Number of teeth: 1
・ Spindle speed: 1516min ^-1
・ Table feed: 2274 mm / min
・ Single blade feed: 1.5mm / tooth
・ Cutting oil: Air blow ・ Cutting distance: 4 m

In FIG. 14, the electron microscope observation photograph (40 times) which observed the damage state of the rake face after a cutting test is shown. The part that looks white in the figure shows the worn part. It can be confirmed that crater wear is suppressed when the hard coating contains W. It was confirmed that all of the sample tools of the present invention showed excellent cutting performance in the high hardness steel and high carbon steel of Example 1. In addition, Table 5 shows the results of measuring the area ratio of a worn white portion by image analysis software.
Among the sample tools of the present invention example, it was confirmed that crater wear was significantly suppressed in the sample tools of Invention Examples 22 and 23 containing a certain amount of W.

(Example 3)
The sample tools of Examples 20 to 23 of the present invention used in Example 2 and the sample tool of Comparative Example 20 are prepared, and the condition that the tool load is larger than that in Example 1 is selected with the work material as SKD11 (60HRC). Then, a cutting test was performed and evaluated. The cutting conditions are shown below. The results of the cutting test are shown in Table 6.

<Conditions for cutting test>
・ Tool: High feed radius mill φ32 × 5 blades (Hitachi Tool Co., Ltd.)
・ Cutter model number: ASRS2032R-5
-Insert model number: EPMT0603TN-8
・ Cutting method: Bottom cutting ・ Work material: SKD11 (60HRC)
・ Incision: 0.5mm in the axial direction, 22mm in the radial direction
・ Number of teeth: 1
・ Spindle speed: 796min ^-1
・ Table feed: 159mm / min
・ Single blade feed rate: 0.2mm / tooth
Cutting oil: When the air blow / flank wear width reached 0.25 mm, the tool life was determined.

In the sample tool of the present invention example, the distance to reach the tool life in the high-efficiency machining of high hardness steel was more than twice that of the sample tool of the comparative example. In particular, the sample tools of Invention Examples 21 and 22 containing W in a more preferable range resulted in a longer distance for reaching the tool life and excellent durability.

Example 4
In Example 1, using the coated cutting tools (sample tools of Invention Examples 1 to 8, 21 to 23, and Comparative Examples 1 to 9) coated with a hard film under the conditions of Tables 1 and 3, the following: A cutting test was conducted on Ni-base superalloys under the conditions and evaluated. The results of the cutting test are shown in Table 7.

<Conditions for cutting test>
・ Tool: Solid end mill φ10 × 2 flute (HES2100 manufactured by Hitachi Tool Co., Ltd.)
Base material: WC (bal.)-Co (11 mass%)-TaC (0.4 mass%)-Cr ₃ C ₂ (0.9 mass%), WC average particle diameter 0.6 μm, hardness 92.4HRA Cemented Carbide / Cutting Method: Side Cutting / Working Material: Ni-19% Cr-18.7% Fe-3.0% Mo-5.0% (Nd + Ta) -0.8% Ti Ni-base alloy with a composition of -0.5% Al-0.03% C (age-hardened)
・ Infeed: axial direction 6mm, radial direction 0.3mm
・ Cutting speed: 40 m / min
・ Single-blade feed amount: 0.04 mm / tooth
・ Cutting oil: Water-soluble cutting oil ・ Cutting distance: 0.2 m

In the example of the present invention, a sample tool showing durability superior to that of the comparative example was obtained in the cutting of the Ni-base superalloy. In particular, the sample tools of Invention Examples 21 and 22 containing W in a preferable range tend to have a small wear width. It was confirmed that the hard film in the present invention contains W, so that it exhibits superior durability in a wide range of work materials.

The disclosure of Japanese application 2013-068602 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims

A substrate;
An intermediate film having a thickness of 1 nm or more and 10 nm or less made of a carbide containing tungsten (W) and titanium (Ti), disposed on the substrate;
The crystal structure disposed on the intermediate film and specified by X-ray diffraction is a face-centered cubic lattice structure, and the Al content ratio (atomic%) is based on the total amount of metal (including metalloid) elements. A hard film made of an AlTi-based nitride or carbonitride having a Ti content ratio (atomic%) of 20% or more, which is 60% or more;
Have
In the intensity profile obtained from the limited field diffraction pattern of the transmission electron microscope, the hard coating has a peak intensity due to the AlN (010) plane of the hexagonal close-packed structure as Ih, and AlN (111 of the face-centered cubic lattice structure. ) Plane, TiN (111) plane, AlN (002) plane, TiN (002) plane, AlN (022) plane, and TiN (022) plane peak intensity, and hexagonal close-packed AlN (010) structure Coated cutting tool that satisfies the relationship of Ih × 100 / Is ≦ 20, where Is is the sum of the peak intensity due to the plane, the AlN (011) plane, and the AlN (110) plane.
The coated cutting tool according to claim 1, wherein the Ih and the Is satisfy a relationship of Ih × 100 / Is ≦ 15.
The coated cutting tool according to claim 1 or 2, wherein the film thickness of the intermediate film is 1 nm or more and less than 6 nm.
The coating according to any one of claims 1 to 3, wherein the hard film has a half width of (200) plane of a face-centered cubic lattice structure specified by X-ray diffraction of 1.8 ° or less. Cutting tools.
In the intensity profile obtained from the limited field diffraction pattern of the film cross-section obtained by a transmission electron microscope, the hard film has a peak intensity due to the same crystal plane on the substrate side and the surface side showing the maximum intensity. 5. The coated cutting tool according to any one of items 4.
In the intensity profile obtained from the limited field diffraction pattern, the peak intensity indicating the maximum intensity attributed to the crystal plane on the surface side is a peak attributed to the AlN (002) plane and TiN (002) plane of the face-centered cubic lattice structure. The coated cutting tool according to claim 5 which is strength.
The coated cutting tool according to any one of claims 1 to 6, wherein the hard coating further contains tungsten (W).
The coated cutting tool according to claim 7, wherein the hard coating has a tungsten (W) content ratio (atomic%) of 1% to 10% with respect to a total amount of metal (including semimetal) elements.
The coated cutting tool according to claim 8, wherein a content ratio (atomic%) of the tungsten (W) is 2% or more and 6% or less.
The coated cutting tool according to any one of claims 1 to 9, wherein the film thickness of the hard coating is 1 µm or more and 5 µm or less.
The hard coating has an Al content ratio (atomic%) of 62% to 70% and a Ti content ratio (atomic%) of 25% or more with respect to the total amount of metal (including metalloid) elements. The total content ratio (atomic%) of Al and Ti is 90% or more with respect to the total amount of metal (including metalloid) elements according to any one of claims 1 to 10. Coated cutting tool.
The coated cutting tool according to any one of claims 1 to 11, wherein the coated cutting tool is a radius end mill or a square end mill.
Forming an intermediate film having a thickness of 1 nm or more and 10 nm or less made of a carbide containing tungsten (W) and titanium (Ti) on the surface of the substrate by performing metal bombardment on the surface of the substrate;
Using a cathode with a magnetic flux density of 18 mT or more near the center of the target, applying a bias voltage of −200 V or more and −70 V or less to the base material, the total amount of metal (including metalloid) elements on the intermediate film On the other hand, the aluminum (Al) content ratio (atomic%) is 60% or more, and the titanium (Ti) content ratio (atomic%) is 20% or more. Forming a film,
The manufacturing method of the coated cutting tool which has this.
The method for producing a coated cutting tool according to claim 13, wherein the hard film is formed at a base material temperature of 450 ° C or higher and 580 ° C or lower.
The method for manufacturing a coated cutting tool according to claim 13 or 14, wherein a heating temperature of the base material before the metal bombardment treatment is 500 ° C or lower.
The method for manufacturing a coated cutting tool according to any one of claims 13 to 15, wherein the hard coating further contains tungsten (W).
17. The coated cutting tool according to claim 16, wherein the hard coating has a tungsten (W) content ratio (atomic%) of 1% to 10% with respect to a total amount of metal (including metalloid) elements. Method.
The method for producing a coated cutting tool according to claim 17, wherein a content ratio (atomic%) of the tungsten (W) is 2% or more and 6% or less.
The method for manufacturing a coated cutting tool according to any one of claims 13 to 18, wherein the coated cutting tool is a radius end mill or a square end mill.