JP5765627B2 - Coated tool having excellent durability and method for producing the same - Google Patents

Description

  The present invention relates to a coated tool excellent in durability used for plastic working such as a cutting tool, forging, and press working, and a method for manufacturing the same.

  Conventionally, in order to improve heat resistance and wear resistance and improve tool life for cutting tools and tools of molds, the surface of the substrate is nitrided such as Ti, Al, Cr, carbonitride, oxide, etc. A coated tool coated with a hard coating is applied. Among them, an AlCr-based nitride hard film has both high heat resistance and wear resistance even at a temperature of 1,000 ° C. or higher, and as a film formation method, a method of forming a film by an ion plating method (Patent Documents 1 and 2). ), A method of forming a film by an arc ion plating method (Patent Documents 3 and 4), and a method of forming a film by a sputtering method (Patent Documents 5 and 6), respectively.

Japanese Patent Laid-Open No. 10-025566 Japanese Patent Laid-Open No. 2003-321764 JP-A-2005-271132 JP 2006-26783 A JP 2000-144378 A JP-A-2005-344148 JP 2007-136597 A

However, in recent years, the working environment for plastic working dies such as cutting tools, forging, and press dies has been to cope with higher hardness of work materials, faster processing time, and dry processing without the use of lubricants. Because it is also required, it has become harsh year after year. For this reason, even with a coated tool that employs a conventional AlCr-based nitride hard coating that exhibits high heat resistance and wear resistance, the adhesion between the base material and the hard coating is not necessarily sufficient in recent severe operating environments. It may not be.
Therefore, providing an intermediate film as in Patent Document 7 is effective for ensuring adhesion. However, depending on the usage environment of the tool, even if an intermediate film for ensuring adhesion is provided, droplets existing inside the film formed by the arc ion plating method or inside the film formed by the sputtering method There is a problem that breakage and damage may occur suddenly due to defects in the coating such as voids that are easily contained in the film.

  The present invention reduces cutting film adhesion and defects inside the film in cutting tools and tools used for plastic processing of metals such as cold and hot forging and press working, thereby preventing sudden film breakage and damage. It is another object of the present invention to provide a coated tool excellent in durability and a manufacturing method thereof.

  The present inventor provided an extremely thin intermediate film between the hard film and the base material, and then controlled the width of the crystal particles of the intermediate film to be constant, thereby It has been found that the adhesion is remarkably increased, and further, the columnar particles of the hard coating that grows directly above the intermediate coating is extremely densified, reducing the defects inside the coating and greatly improving the durability of the tool. .

That is, the present invention is a coated tool in which a coating is coated on the surface of a substrate, and the coating is composed of an AlCr-based nitride or carbonitride hard coating having a hardness of 30 GPa or more, and the hard coating and the substrate. It consists of an intermediate film at the interface, and the intermediate film has a film thickness of 2 to 40 nm and an average width of crystal grains of 40 nm or less, and is made of any one of Ti metal, Ti nitride, carbide, and carbonitride. It is an excellent coated tool. The intermediate coating is preferably a Ti nitride.
The hard coating preferably contains Si. Furthermore, the hard coating preferably contains Ti.
The cross-sectional structure of the hard film is composed of a collection of columnar particles grown in a direction perpendicular to the substrate surface, and the average width of the columnar particles is preferably 0.3 μm or less.

The hard film of the present invention comprises a first hard film immediately above the intermediate film and a second hard film immediately above the first hard film, and the first hard film has a metal component composition of (Al _X Cr _Y Ti _Z ) [However, in atomic%, X + Y + Z = 100, 50 <X <75, 20 ≦ Y <50, 0 <Z ≦ 10], the second hard film has a metal component composition. _{(Al U Cr V Si W)} [ where, U + V + W = 100,50 <U <75,20 ≦ V <50,0 <W ≦ 10 in atomic%] is preferably a nitride or carbonitride. Furthermore, the first hard coating preferably contains 10 atomic% or less of Si as a metal component. Furthermore, it is preferable that a 2nd hard film contains 10 atomic% or less of Ti as a metal component.
The cross-sectional structure of the second hard coating is composed of a collection of columnar particles grown in a direction perpendicular to the substrate surface, and the average width of the columnar particles is preferably 0.3 μm or less.

  The hard coating shows a crystal structure of cubic B1 structure by X-ray diffraction from the surface, and shows the maximum intensity at (111) of its plane index, and the diffraction intensity of (111) is I (111), (200) When the diffraction intensity is I (200) and the diffraction intensity of (220) is I (220), I (111)> I (220)> I (200) is satisfied and I (111) / I (220) It is preferable that> 2.0 is satisfied. Furthermore, it is more preferable that the lattice constant of the cubic B1 structure is larger than 0.414 nm.

The above-mentioned coated tool of the present invention has a film thickness of 2 to 40 nm and an average width of crystal grains of 40 nm by sputtering using a Ti target with a maximum cathode output of 0.1 to 0.2 MW just above the substrate. nitrides of the following Ti or Ti, carbides, an intermediate film is formed consisting of any of carbonitrides, then immediately above the intermediate film, the bias voltage of the negative pressure applied to the substrate - 100 to - 140 V Thus, by a sputtering method using an AlCr target, it can be obtained by a manufacturing method of a coated tool excellent in durability for coating a hard film made of an AlCr nitride or carbonitride. In covering the intermediate film, it is preferable to form a nitride of Ti.
Furthermore, in the coating of the hard film, it is preferable to form the first hard film directly above the intermediate film and the second hard film directly above the first hard film using two types of AlCr-based targets having different compositions. In the coating of the second hard film, it is preferable to use an AlCr-based target containing Si as a metal component.
Further, the bias voltage of the negative pressure applied to the substrate, - 120V~ - is preferably a 140 V.

  In the coated tool provided by the present invention, a dense and fine AlCr-based hard film excellent in heat resistance and wear resistance is also excellent in adhesion to a substrate. The coated tool is excellent in durability when used for metal plastic processing such as cutting tools, cold forging and hot forging, and press working, and can realize an extremely excellent tool life.

An example of the cross-sectional photograph of the hard film by the transmission electron microscope of the sample number 2 is shown. (The straight line in the figure is drawn in order to measure the width of the columnar particles at a position of 0.5 μm from the surface.) An example of the cross-sectional observation photograph of the intermediate | middle film | membrane by the transmission electron microscope of the sample number 1 is shown. (The numbers in the figure indicate the parts subjected to composition analysis.) The schematic diagram of the cross-sectional observation photograph of the intermediate film of the sample number 1 is shown. An example of the cross-sectional observation photograph of the intermediate film by the transmission electron microscope of the sample number 6 is shown. (The symbols and numbers in the figure indicate the composition-analyzed part.) The schematic diagram of the cross-sectional observation photograph of the intermediate film of the sample number 6 is shown. The X-ray diffraction profile of sample number 2 is shown. An example of a scanning electron microscope observation photograph of the film surface of sample number 2 and an ion-excited secondary electron image of the fracture surface is shown. An example of a scanning electron microscope photograph of the film surface of sample number 7 and an ion-excited secondary electron image of the fracture surface is shown. An example of a scanning electron microscope photograph of the film surface of sample number 13 and an example of an ion-excited secondary electron image of the fracture surface It is a figure which shows the profile by the high frequency glow discharge emission analysis of the sample number 2. FIG. It is a figure which shows the profile by the high frequency glow discharge emission analysis of the sample number 7. FIG.

  The inventors of the present invention do not cause film peeling or chipping even under harsh usage environments, so that the film characteristics of AlCr nitride or carbonitride having excellent wear resistance and heat resistance can be exhibited. We have intensively studied methods for improving the adhesion between the material and the hard coating, as well as reducing defects existing inside the hard coating.

  It is effective to provide an intermediate film to improve the adhesion between the base material and the hard film. The inventors investigated the influence of the intermediate film on the structure of the hard film. The columnar structure of the hard film that grows immediately above the intermediate film is a crystal particle existing inside the intermediate film. It has been found that the larger the width, the larger the tendency to grow. In other words, by making the width of the crystal particles in the intermediate film uniformly fine, the columnar structure of the hard film that grows just above it is easy to become fine and dense, and after ensuring the adhesion, Defects such as voids are reduced.

  The present inventors have found that the width of the crystal particles of the intermediate coating becomes extremely fine by setting the maximum output to be applied to the target when coating the intermediate coating to be extremely high compared to the prior art. And while ensuring the outstanding adhesiveness, it was able to be set as the coated tool which was extremely excellent in durability which also reduced the internal defect of the hard film.

First, the structure of the intermediate film in the present invention will be described.
Ti or Ti nitride, carbide, and carbonitride films are all excellent in affinity and adhesion to steel and cemented carbide, and also excellent in adhesion to AlCr-based films. Therefore, these are optimal as an intermediate film provided between the base material and the AlCr-based nitride or carbonitride.
The intermediate film of the present invention may be any of Ti or Ti nitride, carbide and carbonitride, but Ti nitride is particularly excellent in heat resistance and has excellent adhesion with a hard film containing nitrogen. Is also preferable.

In the intermediate coating of the present invention, it is most important to control the film thickness and the width of crystal grains. By setting the film thickness of the intermediate film to 2 to 40 nm, sufficient adhesion between the base material and the hard film can be ensured. If it is too thin, sufficient adhesion between the substrate and the hard coating cannot be ensured. On the other hand, when the thickness is too thick, the columnar particles of the hard coating that grows directly thereon are likely to be coarse and the adhesion tends to decrease, and the durability of the tool under a severe use environment becomes insufficient.
The film thickness of the intermediate coating is more preferably 3 nm or more and / or 30 nm or less, and further preferably 5 nm or more and / 20 nm or less.
The film thickness of the intermediate film of the present invention can be evaluated by observation with a transmission electron microscope. Furthermore, by performing composition analysis such as mapping, the interfaces of the base material, the intermediate film, and the hard film become clear, and the film thickness of the intermediate film can be measured more accurately.

By setting the average width of the crystal particles of the intermediate coating to 40 nm or less, the hard coating grows finely and extremely densely from directly above the intermediate coating, so that the adhesion with the substrate can be improved. And since a space | gap becomes very few in the whole hard film | membrane, it becomes a film | membrane which is excellent in durability. When it becomes coarse, the hard film grows in accordance with the average width of the large crystal grains, so that the columnar particle width of the hard film increases. And since the clearance gap between columnar particles becomes large, it will become easy to generate | occur | produce a space | gap, and it will become a membrane | film | coat in which adhesiveness falls and durability is scarce. The average width of the crystal particles of the intermediate film is preferably 20 nm or less, because the entire hard film becomes more dense and the adhesion is improved, which is excellent in durability. Furthermore, it is preferable that it is 10 nm or less. Furthermore, it is 5 nm or less.
The average width of the crystal particles of the intermediate film is measured from the width of the crystal particles in the direction perpendicular to the film thickness direction using a transmission electron microscope. Depending on the incident direction of the electron beam at the time of observation, the appearance of the crystal particles is different, and individual crystal particles can be identified as differences in the continuity and contrast of the lattice image. However, when the observation magnification is low, it is difficult to identify individual crystal particles and accurately measure the width of the crystal particles. Therefore, the observation magnification is set to about 4 million times, which is a magnification that can clearly confirm the difference in the continuity of the lattice image and the contrast. And by measuring 50 or more continuous crystal particles, it was confirmed that the average value of those measured values converged, so the average width of the crystal particles of the intermediate film from the 50 continuous crystal particles Asked.

Next, the hard coating will be described. The hard coating is imparted with higher wear resistance by setting the hardness to 30 GPa or more as an AlCr-based nitride or carbonitride that is a film type having excellent heat resistance and wear resistance. More preferably, it is 35 GPa or more, More preferably, it is 40 GPa or more.
Here, in the present invention, the AlCr-based nitride or carbonitride refers to a film in which the total of Al and Cr in the metal component is 70 atomic% or more in atomic%. In order to achieve both high heat resistance and wear resistance, it is preferable that the total of Al and Cr in the metal components is 80% or more in atomic%. Moreover, it is more preferable that Al content which is excellent in heat resistance is larger than Cr content.
The film thickness of the hard coating of the present invention is preferably 1 to 10 μm. If it is too thin, durability will be reduced. If it is too thick, breakage tends to occur. And if adhesion strength with a base material and surface smoothness are considered, 2 micrometers or more and / or 5 micrometers or less are more preferred.

The hard coating preferably contains Si as a metal component, so that the crystal grains of the hard coating are refined and the hardness of the hard coating is improved, so that the wear resistance of the tool is improved.
The hard coating preferably contains Ti as a metal component, so that the hardness of the hard coating is improved, and thus the wear resistance of the tool is improved.

By making the average width of the columnar particles grown in the vertical direction of the hard coating 0.3 μm or less, the entire hard coating becomes more dense, and it is preferable that particles fall off from the coating surface during use of the tool. . Further, even when the particles fall off, the individual columnar particles are fine, so that they do not suddenly break the coating.
When the average width of the columnar particles of the hard coating is larger than this, the hard coating particles are likely to fall off under a severe use environment where a high load is applied, and the tool life is shortened.
The width of the columnar particles of the hard coating can be measured from cross-sectional observation with a transmission electron microscope or a scanning electron microscope. The measurement location was a position having a depth of 0.5 μm from the coating surface. And by observing the width of 50 or more continuous columnar particles, it was confirmed that the average value of those widths converged, so the average of the columnar particles of the hard coating from the 50 columnar particles that were continuous The width was determined.

In order to satisfy adhesion and wear resistance and heat resistance at a high level, the amount of Si and Ti added to the hard coating is adjusted, and the first hard coating immediately above the intermediate coating and the first hard coating directly above the first hard coating are adjusted. It is preferable to change the composition with 2 hard coatings.
At this time, the composition of the metal component of the first hard coating immediately above the intermediate coating is (Al _X Cr _Y Ti _Z ) [However, in atomic%, X + Y + Z = 100, 50 <X <75, 20 ≦ Y <50, Nitride or carbonitride of 0 <Z ≦ 10] is preferable.
As AlCr-based nitride or carbonitride, in order to achieve both a certain level of wear resistance and heat resistance, the Al content is set to 50 <X <75, and the Cr content is set to 20 ≦ Y <50. .
When the Al content is less than this, the heat resistance tends to be lowered, and when it is more than this, the wear resistance tends to be lowered. More preferably, the atomic% is 55 or more and / or 70 or less.
When the Cr content is out of the range of 20 ≦ Y <50, the wear resistance tends to decrease.
And in the 1st hard film immediately above an intermediate film, adhesiveness with the intermediate film containing Ti improves more by containing 10 atomic% or less of Ti. Furthermore, wear resistance is further increased by containing Ti. When it exceeds this, heat resistance will fall easily.

The second hard coating on the surface side has a composition of the metal component (Al _U Cr _V Si _W ) [However, in atomic%, U + V + W = 100, 50 <U <75, 20 ≦ V <50, 0 <W ≦ 10 Nitride or carbonitride is preferred.
As the AlCr-based nitride or carbonitride, in order to achieve both a certain level of wear resistance and heat resistance, the second hard coating also has an Al content of 50 <X <75 and a Cr content of 20 ≦ Let Y <50. More preferably, the atomic% is 55 or more and / or 70 or less.
And by containing 10 atomic% or less of Si, crystal grains are refined and the hardness of the hard coating is improved, so that the wear resistance of the tool is improved. And since each crystal particle is refined | miniaturized, it becomes difficult to generate | occur | produce the membrane | film | coat damage by dropping of a crystal particle. If it is more than this, the toughness of the hard coating will decrease. The hard coating on the surface side preferably has both high wear resistance and toughness, and for that purpose, the Si content is preferably 8 atomic% or less. Further, it is more preferably 5 atomic% or less.

Further, the first hard coating preferably contains 10 atomic% or less of Si as a metal component in order to further improve the wear resistance. When it exceeds this, the toughness of the whole film will fall.
The second hard film preferably contains 10 atomic% or less of Ti as a metal component in order to further improve the wear resistance. When it exceeds this, the heat resistance of the whole film will fall. More preferably, it is 5 atomic% or less.

  Even when the hard film is composed of the first hard film and the second hard film, the total film thickness of the hard film is preferably 1 to 10 μm. In this case, the film thickness ratio between the first hard film and the second hard film is preferably 5 to 25% for the first hard film and 75 to 95% for the second hard film.

The hard film of the present invention has a peak corresponding to the (111) plane at 36.0 to 40.0 of the cubic structure by X-ray diffraction using Cukα as a radiation source (200 to 42.0 to 46.0). ) The peak corresponding to the plane, and the peak corresponding to the (220) plane at 62.0 to 66.0 are easily observed.
The inventor has found that when these orientation strengths are in a certain relationship, the hard coating becomes denser and harder, and the durability of the tool is further improved. That is, when the (111) diffraction intensity of the hard coating of the present invention is I (111), the diffraction intensity of (200) is I (200), and the diffraction intensity of (220) is I (220), the orientation intensity is It is preferable that I (111)> I (220)> I (200) and I (111) / I (220)> 2.0.
These preferable orientations can be obtained by adjusting the film composition and film forming conditions. In particular, the relationship of the orientation strength ratio tends to be easily influenced by the film forming conditions.
In order to obtain a preferred orientation among the examples of the present invention, it is preferable to control the maximum power input to the target so that the average width of the crystal grains of the intermediate coating is smaller than 10 nm. More preferably, it is 5 nm or less. Then, a hard coating composed of a first hard coating and the second hard film, each film formation, the bias voltage of the negative pressure applied to the substrate - easily obtained by greater than 120V. More preferably - it is 140V.
And even if it is said preferable film-forming conditions, content of Al of a 1st hard film and a 2nd hard film shall be 55 atomic% or more, respectively, and also Ti and / or Si should be contained in each film. Is preferred.

  After the crystal structure satisfies the above relationship, the lattice constant calculated from the (111) plane of the cubic structure of the hard film increases, so that the residual stress inside the film becomes higher and the hardness increases. When the lattice constant calculated from the (111) plane of the cubic crystal structure is larger than 0.414 nm, the hard coating is more dense and easy to have high hardness, and tends to exhibit excellent wear resistance.

  When the coated tool of the present invention is used as a cutting tool or a mold, it is preferable that the surface of the hard coating is smooth because the resistance during use is small. And when forming the hard film of this invention by sputtering method, generation | occurrence | production of a droplet is very few and a smooth film can be obtained and the surface roughness by JIS-B-0601 (2001) is arithmetic mean roughness. It is possible to obtain a preferable surface state with a thickness Ra of 0.06 μm or less and a maximum height Rz of 1.0 μm or less.

  The hard coating employed in the present invention can exhibit its characteristics by being an AlCr-based nitride or carbonitride having a specific intermediate coating. Therefore, even if a part of the hard film takes the form of oxide, boride, or sulfide, the excellent characteristics of the AlCr-based nitride or carbonitride having a specific intermediate film are significantly inhibited. There is no effect of the present invention.

In the present invention, in addition to controlling the film thickness of the intermediate film to be extremely thin, it is necessary to finely control the average width of the crystal grains. However, in the conventional film forming method, even if an intermediate film having a thin film thickness is provided in order to make the average width of the crystal particles fine, crystal particles having a continuous crystal structure may grow greatly. Thus, it has been found that the crystal particles can be refined by increasing the maximum power input to the target higher than ever before when the intermediate coating is applied. Specifically, the average width of the crystal grains of the intermediate film is made extremely fine as 40 nm or less by setting the maximum output to be applied to the target by a sputtering method using a Ti target to 0.1 to 0.2 MW. Can do. More preferably, it is 0.12 MW or more.
In order to increase the input power to the target, HPPMS (High Power Pulse Magnetron Sputtering), which can apply extremely high power instantaneously, can be used.
When HPPMS is used, abnormal discharge easily occurs on the target surface. Therefore, the average output is set to about 2 kW, high power is instantaneously supplied only for an extremely short time of about 20 μs, and the direct current supplied to the target is periodically changed in a pulse shape to suppress abnormal discharge. It is preferable.

However, if the time of the maximum power input to the target is made extremely short and the power is further supplied in a pulse shape, the film formation rate is extremely low and the productivity is deteriorated. Furthermore, if an extremely high maximum power is applied to the formation of a hard coating, the load on the apparatus becomes extremely large. The present inventor has intensively studied, and if the average width of the crystal particles of the intermediate coating directly above the base material is controlled to a certain level or less, the columnar particles of the hard coating immediately above the size are reduced according to the average width of the crystal particles of the intermediate coating I found out. Therefore, the target used for forming the hard coating may be merely supplied with a normal average power of about several kW without instantaneously supplying extremely high power.
And in the coating of the hard film, by using a method in which the negative bias voltage applied to the base material is set to 100 to 140 V by a sputtering method using an AlCr target, the hard film becomes fine and dense. The hardness of the nitride or carbonitride can be 30 GPa or more.
Furthermore, in the coating of the hard film, a single layer is formed by forming the first hard film directly on the intermediate film and the second hard film directly on the first hard film using two types of AlCr-based targets having different compositions. It is preferable because the adhesion, wear resistance and heat resistance can be further enhanced than those of the hard coating. And in the coating of the second hard film, it is preferable to use an AlCr-based target containing Si as a metal component, because the structure of the film surface is refined and wear resistance is improved, and particle dropout is easily suppressed. .

  In consideration of the use of the hard coating of the present invention as a plastic working die or cutting tool, the metal material used as the base material is preferably cold die steel, high-speed steel, or cemented carbide. And when the energy at the time of film formation is high like HPPPMS, it becomes easy to form the area | region where the surface of the base material concentrated carbon compared with the inside. And the component of the intermediate film tends to form a compound with carbon on the surface of the substrate, which is preferable because the adhesion is increased.

  A double-edged ball having an outer diameter of 5 mm, using a base material made of ultra-fine cemented carbide having a WC crystal grain size of 0.4 μm, a Co content of 6 mass%, and a V content of 0.1 mass%. Two types were prepared: an end mill and a test piece having a mirror finish of 20 mm in diameter and 5 mm in thickness. These substrates were ultrasonically cleaned and degreased in a hydrocarbon-based solvent and subjected to the surface treatment described below to prepare Sample Nos. 1 to 14 as the present invention and Comparative Examples. The test piece was used for evaluating the characteristics of the film, and the ball end mill was used for the cutting test.

The film forming means employs a sputtering method in which a bias voltage is applied to the substrate, and in order to continuously form the intermediate film, the first hard film, and the second hard film in the same chamber, Five sputter evaporation sources were installed. One of them was for the intermediate film, 2 for the first hard film, and 2 for the second hard film.
A Ti target was installed as a sputtering power source (cathode 1) for the intermediate coating.
Two Al65Cr35 targets were installed in the sputtering power source (cathodes 2 and 3) for the first hard coating (chemical formula is a ratio by atom, the same applies hereinafter).
Two Al55Cr43Si2 targets were installed in the sputtering power source (cathodes 4 and 5) for the second hard coating.
The size of the sputter target is 500 mm long and 88 mm wide.

  A direct current power source was used for the sputtering power source and the bias power source. The cathode 1 was provided with a pulse module, an average output of 2 kW and a discharge time of 20 μs per cycle were constant, and an intermediate film was formed by changing the frequency, maximum output, and discharge time for each sample.

The bias power source is connected to the substrate and independently applies a negative bias voltage to the substrate. 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. Ar, Kr, and N ₂ were used as the introduction gas and introduced from the gas supply port.

First, heating is performed for 90 minutes with the substrate temperature at 500 ° C. by the heater in the film forming apparatus. After the pressure in the vacuum container (chamber) reaches 4 × 10 ⁻³ Pa, the Ar gas is evacuated. The pressure inside the furnace was 0.2 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.

In sample numbers 1-7, 9-12, and 14 in which the intermediate film is coated with Ti nitride, the pressure in the container is evacuated to 1 × 10 ⁻³ Pa, and the temperature of the substrate is kept constant at 450 ° C. N ₂ gas was introduced under a constant flow rate of Ar gas of 295 ml and Kr gas of 200 ml so that the pressure in the container was 580 mPa.
The bias voltage was set to -100 V, the anode voltage was set to -90 V, and power was supplied to the cathode 1 in a pulsed manner to coat the intermediate film. Subsequently, 4 kW of sputtering power was supplied to each of the cathodes 2 and 3 to coat the first hard coating.
Subsequently, with the power supply of the cathode 1 stopped, and with the power supply of the cathode 2 continued, a 4 kW sputtering power supply was supplied to the cathodes 4 and 5 respectively and held for 60 minutes, and the second hard coating was applied. Covered.
In Sample No. 7, an intermediate film was coated by a normal sputtering method without using a pulse modular.

In sample number 8 where the intermediate film is coated with Ti metal, the pressure in the container is evacuated to 1 × 10 ⁻³ Pa, and the pressure in the container becomes 580 mPa under a constant flow rate of 200 ml of Kr gas. Ar gas was introduced. The bias voltage was set to -100 V, the anode voltage was set to -90 V, and power was supplied to the cathode 1 in a pulsed manner to coat the intermediate film.
Subsequently, the flow rate was changed to 295 ml of Ar gas and 200 ml of Kr gas at a constant flow rate, and N ₂ gas was introduced so that the pressure in the container was 580 mPa. The film forming conditions for the first hard film and the second hard film are the same as those for coating the nitride.

  In Sample No. 13, the intermediate coating was not formed, and the hard coating was coated directly on the substrate, and in Sample No. 14, only the cathodes 2 and 3 were used for forming the hard coating. Table 1 shows the details of the film forming conditions for each film.

  Each sample was cooled to 200 ° C. or lower, taken out from the container, and the film characteristics were evaluated using a test piece. The coating composition was analyzed using an electron probe microanalyzer (EPMA: JXA-8900R manufactured by JEOL Ltd.). The analysis was conducted by mirror-polishing the cross section of the film with the test piece tilted 5 degrees with respect to the outermost surface of the film, and then averaging the values as wide as possible within each layer of the intermediate film, the first hard film, and the second hard film on the polished surface. The analysis area of each layer was selected so that 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.

  The hardness of the hard coating was measured using a nanoindentation device manufactured by Elionix Co., Ltd. In order to measure the hardness of the film, the test piece was tilted by 5 degrees, and after mirror polishing, a region where the maximum indentation depth was less than about 1/10 of the thickness of each layer was selected within the polishing surface of the film. 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, the hardness of single crystal Si is also measured simultaneously as a standard sample. 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. The measurement place measured the hardness of the surface side which is a 2nd hard film.

In order to measure the film thickness of the intermediate film, the crystal particle width, and the width of the columnar particles of the hard film, the film cross section of each sample was observed using a transmission electron microscope (TEM). The film thickness was also measured by conducting a composition analysis.
First, a sample was cut, a dummy substrate was bonded using an epoxy resin, cut, Mo reinforcing ring bonding, polishing, dimple ring, and Ar ion milling were performed to create a cross-sectional TEM sample. Finally, carbon deposition was performed. The equipment was a JEM-2010F field emission type transmission electron microscope manufactured by JEOL Ltd., and the acceleration voltage was 200 kV.
FIG. 1 shows a measurement example of the average width of the columnar particles of the hard film of sample number 2. The width of the columnar particles of the hard coating was measured by measuring the width of the columnar particles contacting when a straight line was drawn parallel to the substrate surface at a position of 0.5 μm in the depth direction from the coating surface. Fifty columnar particles were measured and used as the average width of the hard coating columnar particles. The other samples were measured in the same manner.

FIG. 2 shows an example of an observation photograph of the intermediate film of sample number 1. FIG. 3 shows a schematic diagram thereof. There are observed crystal grains in which the lattice images continuously appear dark and crystal grains in which the crystal orientation is different and appear bright. The width of each crystal grain was measured from the center width of the crystal grain in a direction perpendicular to the film thickness. Then, the width of 50 continuous crystal grains was measured and used as the average width of the crystal grains of the intermediate coating.
In FIG. 4, the example of the observation photograph of the intermediate film of the sample number 6 is shown. FIG. 5 shows a schematic diagram thereof.
The other samples were measured in the same manner.

X-ray diffraction was performed from the surface of the hard coating, and the crystal structure of each sample was examined. The equipment used was an X-ray diffractometer manufactured by Rigaku Corporation, with a tube voltage of 120 kV, a tube current of 40 mA , an X-ray source Cukα, an X-ray incident angle of 5 degrees, an X-ray incident slit of 0.4 mm, and 2θ of 20 to 90. Measured under the condition of degree. From the results of the X-ray diffraction profile with the background removed, the intensity order of (111), (200), (220), (111) and (220) intensity ratio, (111) among the plane indices of the cubic B1 structure. The lattice constant calculated from the above was measured.
FIG. 6 shows an XRD profile of Sample No. 2, which is an example of the present invention. It is confirmed that the strongest strength surface is (200), and then (220) and (111).

The cutting test was conducted using a ball end mill under the following cutting conditions.
It has been confirmed that the film was formed under the same conditions and that the test piece and the ball end mill have the same film characteristics.
Work material: Martensitic stainless steel (HRC52)
Tool rotation speed: 20000 rotation / min Table feed amount: 4000 m / min Cutting depth: 0.4 mm in the axial direction, pick feed 0.2
mm
Machining method: Dry cutting Life judgment: Cutting length until maximum wear width reaches 0.1mm, but rounded down to less than 10m

  Table 3 shows the measurement results of the film properties and the cutting test results.

The film thickness of the intermediate film of the present invention and the average width of the crystal grains are appropriately controlled. Therefore, the hard coating was fine and dense from the interface with the intermediate coating, and had excellent adhesion and high hardness. Among them, Sample Nos. 1, 2, 8, and 11 in which the average width and orientation strength of the columnar particles of the hard coating are preferable have particularly excellent tool life.
In Sample No. 3, which is a comparative example, the film thickness of the intermediate film was large, the adhesion was insufficient, and the tool life was shortened.
In Sample Nos. 7 and 8 which are comparative examples, the crystal grain width of the intermediate coating was not sufficiently refined, and the hard coating grown immediately above was not densified and poor adhesion, resulting in a short tool life.
Sample No. 12, which is a comparative example, had a low negative pressure bias voltage applied during the coating of the hard coating, so the columnar particles of the hard coating were coarse and not densified, the coating strength was low, and the tool life was shortened.
Since sample number 13 which is a comparative example does not provide an intermediate film, it has very poor adhesion to the substrate. Further, the columnar particles of the hard film were coarse and not densified, and film peeling occurred at the initial stage of cutting.

In order to compare the surface of the hard coating and the cross-sectional structure, sample number 2 as an example of the present invention and sample numbers 7 and 13 as comparative examples were observed. The outermost surface of the film was observed with a scanning electron microscope, and a cross-sectional photograph of the film was prepared with a focused ion beam (FIB) and observed with an ion-excited secondary electron image (SIM). 7 to 9 show observation photographs of the respective samples.
Comparing the tissue forms of Sample Nos. 2, 7, and 13, it is confirmed that the form of the hard film growing immediately above changes depending on the form of the intermediate film.
In Sample No. 2, which is an example of the present invention, the hard coating is dense and fine, and no voids are found in the interface with the intermediate coating and in the hard coating. On the other hand, in Sample No. 7 where the crystal grain width of the intermediate coating is large, there are many voids from the interface with the intermediate coating, and the columnar particles of the hard coating are coarsened. In particular, in use number 13 having no intermediate film, there are many voids and the columnar particles are significantly coarsened.

Sample No. 2 as an example of the present invention and Sample No. 7 as a comparative example were subjected to composition analysis in the depth direction by high-frequency glow discharge emission analysis. Respectively, and the results are shown in Figure 10 and 11. From the outermost surface of the hard coating (sputtering time 0 seconds) toward the substrate, the second hard coating, the first hard coating, the intermediate coating, and the substrate were analyzed.
In the example of the present invention, it is confirmed that the carbon in the base material is diffused outward just below the intermediate film containing Ti as a main component, that is, on the substrate surface side. On the other hand, although the comparative example includes an intermediate film mainly composed of Ti, no outward diffusion of carbon was confirmed.
Sample No. 2 was deposited by the manufacturing method of the present invention, the energy at the time of forming the intermediate film is high, easy carbon contained in the base material by forming a carbide at the interface by the outer direction diffusion, of the substrate It can be seen that a carbon-enriched region can be formed near the surface.

  In preparation of Sample Nos. 15 to 28, the intermediate film was formed under the same conditions as Sample No. 1 in Example 1. The hard film was formed by changing various targets to be installed on the cathodes 2, 3, 4, and 5 used in Example 1 and adjusting the electric power supplied to each target. The measurement of the film properties and the cutting test were evaluated under the same conditions as in Example 1. Table 4 shows the film compositions of Sample Nos. 15 to 28 of the present invention. Table 5 shows the measurement results of the film properties and the cutting test results.

Sample numbers 15 to 28, which are examples of the present invention, had an intermediate film thickness of 5 nm and an average width of crystal grains of 5 nm. The hard coating was also fine and dense, and showed excellent cutting performance.
In particular, in Sample Nos. 15, 17, 18, 19, 22, 23, 24, 27, and 28, which satisfy the preferable conditions of the average width and orientation strength of the hard coating columnar particles, the cutting distance is 600 m or more and the tool life is extremely excellent. showed that.

As evaluation with a real metal mold, a cold forging metal mold for cup molding made of SKH51 (hardness 64HRC) was produced, and the life evaluation in the real metal mold of the present invention was performed. The mold has a diameter of 30 mm and a height of 250 mm, and a working surface for cup molding is processed at the tip. First, the raw material was roughly processed into a mold shape in the annealed state. Then, this was quenched by nitrogen gas cooling from heating and holding at 1180 ° C. in a vacuum, tempered at 560 ° C., and tempered to 64 HRC.
Finally, finish processing (polishing with diamond paste + aero lapping treatment with Aero Lap YT-300 manufactured by Yamashita Towers Co., Ltd.) is performed on the work surface of the mold adjusted to the final shape in Example 1 The film of the sample number 2 which is the evaluated example of the present invention and the sample number 7 which is a comparative example was coated.

  Cold forging was performed on the cold forging die for cup forming produced above using the carbon steel for mechanical structure S50C defined in JIS as a workpiece. The durability of the mold was evaluated based on the number of shots when vertical flaws occurred in the product.

  The mold coated with the hard film of Sample No. 2 as an example of the present invention could be stably processed for 20000 shots or more. On the other hand, in the mold coated with the hard film of Sample No. 7 as a comparative example, galling occurs after about 3000 shots, and it is confirmed that the durability of the coated mold coated with the hard film of the present invention is extremely excellent. It was done.

In the coated tool of the present invention, the film exhibits excellent adhesion, and has both heat resistance and wear resistance. Therefore, the tool life can be significantly improved by using it for cutting tools and tools for plastic working such as forging and pressing in cold and warm conditions.
And considering the excellent wear resistance, oxidation resistance and adhesion of the coating of the present invention, depending on the conditions of use, it is used not only for iron-based but also for processing Ni-based alloys, titanium, aluminum, and alloys thereof. Cutting tools, plastic working dies, die castings used in contact with molten metal and dies used for casting, or casting pins, piston rings used for die casting machines, etc. Can also be diverted.

Claims (16)

A coated tool having a coating on the surface of a substrate, the coating comprising an AlCr-based nitride or carbonitride hard coating having a hardness of 30 GPa or more, and an intermediate coating at the interface between the hard coating and the substrate The intermediate film is excellent in durability characterized by being composed of any one of Ti or Ti nitride, carbide, carbonitride having a film thickness of 2 to 40 nm and an average width of crystal grains of 40 nm or less. Coated tool. The coated tool excellent in durability according to claim 1, wherein the intermediate film is a nitride of Ti. 3. The coated tool with excellent durability according to claim 1 or 2, wherein the hard coating contains Si as a metal component. 4. The coated tool with excellent durability according to claim 1, wherein the hard coating contains Ti as a metal component. The cross-sectional structure of the hard film is composed of a collection of columnar particles grown in a direction perpendicular to the substrate surface, and the average width of the columnar particles is 0.3 µm or less. A coated tool having excellent durability as described in Crab. The hard film is composed of a first hard film immediately above the intermediate film and a second hard film immediately above the first hard film. The first hard film has a metal component composition of (Al _X Cr _Y Ti _Z ) [However, The nitride or carbonitride of X + Y + Z = 100, 50 <X <75, 20 ≦ Y <50, 0 <Z ≦ 10] in atomic%, the second hard film has a metal component composition of (Al _U Cr _V Si _W ) [wherein, U + V + W = 100 in atomic%, 50 <U <75, 20 ≦ V <50, 0 <W ≦ 10] nitride or carbonitride. The coated tool excellent in durability in any one of thru | or 5. The coated tool with excellent durability according to claim 6, wherein the first hard film contains 10 atomic% or less of Si as a metal component. The coated tool with excellent durability according to claim 6 or 7, wherein the second hard coating contains 10 atomic% or less of Ti as a metal component. The cross-sectional structure of the second hard film is composed of a collection of columnar particles grown in a direction perpendicular to the substrate surface, and the average width of the columnar particles is 0.3 µm or less. A coated tool having excellent durability according to any one of the above. The hard coating exhibits a crystal structure of cubic B1 structure by X-ray diffraction from the surface, shows the maximum intensity at (111) of its plane index, and the diffraction intensity of (111) is I (111), (200) When I (200) and (220) are I (220), I (111)> I (220)> I (200) is satisfied and I (111) / I (220) )> 2.0 is satisfied, The coated tool having excellent durability according to any one of claims 1 to 9. The coated tool excellent in durability according to claim 10, wherein the lattice constant of the cubic B1 structure is larger than 0.414 nm. A method of manufacturing a coated tool for coating a surface of a substrate with a film thickness of 2 to 40 nm directly above the substrate by sputtering using a Ti target with a maximum cathode output of 0.1 to 0.2 MW. An intermediate film made of Ti or Ti nitride, carbide or carbonitride with an average width of crystal grains of 40 nm or less is formed, and then a negative pressure applied to the substrate is directly above the intermediate film. a bias voltage - 100 - with 140 V, by a sputtering method using a AlCr based target, method for producing a coated tool having excellent durability, which comprises coating the hard film composed of a nitride or a carbonitride of AlCr based . 13. The method for manufacturing a coated tool with excellent durability according to claim 12, wherein the intermediate film is coated with a nitride of Ti. The hard coating is characterized in that two types of AlCr-based targets having different compositions are used to form a first hard coating just above the intermediate coating and a second hard coating just above the first hard coating. A method for producing a coated tool having excellent durability according to 12 or 13. The method for manufacturing a coated tool with excellent durability according to claim 14, wherein an AlCr-based target containing Si as a metal component is used for coating the second hard film. The coating of the hard film, the bias voltage of the negative pressure applied to the substrate - 120V~ - 140V and manufacturing method of the coated tool having excellent durability according to any one of claims 12 to 15, characterized in that.