JP7385223B2 - Composite hard carbon coating, composite hard carbon coating coated tool, and method for manufacturing composite hard carbon coating - Google Patents

Description

The present invention relates to a thick composite hard carbon coating having high hardness, a composite hard carbon coating coated tool, and a method for manufacturing the composite hard carbon coating, and particularly to improving the adhesion of the coating and peeling even when the coating has high hardness. This is related to technology that can suppress this.

Various processing tools such as cutting tools such as drills, end mills, milling cutters, and bits, non-cutting tools such as forming taps, rolling tools, press dies, etc., and various tool members such as friction parts that require wear resistance. Various proposals have been made to improve wear resistance and durability by coating the surface of a base material made of cemented carbide or high speed tool steel (HSS) with a hard carbon film. For example, a hard carbon film (DLC film) proposed in Patent Document 1 is such a film.

In Patent Document 1, WC (cemented carbide), which is a film-forming object in which an intermediate layer containing carbon such as SiC is formed on the surface of a metal base, is placed in a vacuum chamber, and the inside of the vacuum chamber is filled with hydrogen gas. A trigger discharge is generated in a cathode electrode made of graphite arranged in a cylindrical anode electrode and a trigger electrode insulated from the cathode electrode, and the arc discharge induced between the cathode electrode and anode electrode is WC. A method for producing a diamond film has been proposed in which a diamond film is formed on the surface to form an ultra-nano microcrystalline diamond film (UNCD film) of about 3 to 20 nm, which is a type of hard carbon film. In this diamond film manufacturing method, for example, a cylindrical anode electrode, a cathode electrode made of graphite arranged coaxially within the anode electrode, and a cathode electrode arranged coaxially within the anode electrode insulated from the cathode electrode. A coaxial plasma jet gun with a trigger electrode is used, and droplets with a small charge-to-mass ratio are not ejected from the anode electrode, but minute carbon vapor (carbon ions) with an electric charge are ejected from the anode electrode. UNCD, which is a film of ultra-nano microcrystalline diamond, is formed on the surface of the substrate.

In the UNCD film proposed in Patent Document 1, an intermediate layer of SiC, which is a seed layer having a crystal structure similar to that of diamond, is formed on the surface of a WC base material to improve adhesion. Even if a carbide such as SiC is used as an intermediate layer, sufficient adhesion of the UNCD film to the base material cannot be obtained, and therefore desirable performance in terms of wear resistance and heat resistance cannot be obtained.

On the other hand, in Patent Document 2, the adhesion between an iron-based base material and a UNCD film laminated thereon via an intermediate layer of W is improved, and ultra-nano nanoparticles with excellent wear resistance and heat resistance are used. In order to provide a substrate coated with a crystalline diamond coating, a first hard carbon layer is formed on the surface of an iron-based substrate or a WC substrate by the coaxial plasma jet gun in a vacuum, and the first hard carbon layer is coated with a crystalline diamond coating. A hard carbon coated substrate has been proposed which includes a second hard carbon layer deposited thereon by a coaxial plasma jet gun in hydrogen. According to this, a W layer is formed on an iron-based base material, and a first hard carbon layer having good adhesion to W is formed on the W layer using the coaxial plasma jet gun in a vacuum. Since the second hard carbon layer, which is compatible with the first hard carbon layer and has excellent abrasion resistance, is formed in hydrogen using the coaxial plasma jet gun, a coating with excellent adhesion and abrasion resistance can be obtained. has been done. In the above Patent Document 2, the first hard carbon layer and the second hard carbon layer formed by a coaxial plasma jet gun are ultra-nano microcrystalline diamond coatings (UNCD films), but to be more precise, they are several nanocrystalline diamond coatings. It is a mixed phase film (UNCD/a-C film) of diamond crystals and amorphous carbon, and is a type of hard carbon film such as diamond-like carbon (DLC).

Japanese Patent Application Publication No. 2007-247032 Japanese Patent Application Publication No. 2010-043347

Incidentally, the demand for wear resistance for tools never ends, and higher hardness and film thickness are desired for wear-resistant coatings for tools. For this reason, the wear-resistant coating for tools has a coating hardness of 50 GPa or more, and with such coating hardness, it is possible to roughen the surface of ferrous metals such as high-speed tool steel and cemented carbide such as WC. If an attempt is made to form a film with a thickness of more than 1 μm without using any of the above methods, the film proposed in Patent Document 2 will peel off, making it impossible to make the film thicker, and there is a problem in that wear or peeling will occur at an early stage.

The present invention has been made against the background of the above circumstances, and its objects are to provide a composite hard carbon coating, a composite hard carbon coating coated tool, and a composite hard carbon coating having high hardness that can be formed into a thick film. An object of the present invention is to provide a method for manufacturing a carbon film.

As a result of various studies against the background of the above circumstances, the present inventors have discovered that the first layered mixed phase film of several nano-sized diamond crystals and amorphous carbon, and the second layered layer of several nano-sized diamond crystals and amorphous carbon Focusing on the density of the mixed phase coating of diamond crystals and amorphous carbon, we applied it to iron-based materials or cemented carbide materials while adjusting the arc discharge potential and heater temperature of the coaxial plasma jet gun. When a film is formed and the density of the first hard carbon layer on the base material side is lower than the density of the second hard carbon layer thereon, even if the hardness and thickness of the entire film are increased, the relative It has been found that since the first hard carbon layer with a low density functions as a buffer layer, peeling of the coating is suppressed as a whole and high wear resistance is obtained. The present invention has been made based on this knowledge.

That is, the gist of the first invention is a method for manufacturing a composite hard carbon film, in which a cylindrical anode electrode and the cylindrical anode are formed in a vacuum chamber in an ultra- high vacuum substantially free of hydrogen. Using a coaxial arc plasma gun that discharges between a graphite cathode electrode arranged coaxially within the electrode, high-energy plasma particles emitted from the opening at the tip of the cylindrical anode electrode are a first hard carbon layer forming step of forming a first hard carbon layer on the tool base material by applying it to part or all of the tool base material; and a step of forming a first hard carbon layer on the tool base material; In a high vacuum, the coaxial arc plasma gun, or a coaxial arc plasma gun different from the coaxial arc plasma gun, in a temperature setting state where the temperature of the tool base material is lower than the first hard carbon layer forming step. forming a second hard carbon layer on the first hard carbon layer by applying high-energy plasma particles to part or all of the tool base material using The purpose is to include the process and.

The gist of the second invention is that the first hard carbon layer has a thickness of 0.2 μm to 3.0 μm and a density of 2.1 g/cm 3 to 2.4 g/cm 3 , and The hard carbon layer has a thickness of 1.0 μm to 9.0 μm and a density of 2.5 g/cm 3 to 3.0 g/cm 3 .

According to the method for manufacturing a composite hard carbon coating of the first invention, in a vacuum chamber, in an ultra-high vacuum, a cylindrical anode electrode and a cathode electrode made of graphite coaxially arranged in the cylindrical anode electrode are connected. By applying high-energy plasma particles emitted from the opening at the tip of the cylindrical anode electrode to part or all of the tool base material using a coaxial arc plasma gun that discharges electricity during the a first hard carbon layer forming step of forming a first hard carbon layer on a base material; and a step of forming a first hard carbon layer in an ultra-high vacuum that does not substantially contain hydrogen in the vacuum chamber. Using the coaxial arc plasma gun or a coaxial arc plasma gun different from the coaxial arc plasma gun, high-energy plasma particles are applied to the tool in a temperature setting state in which the temperature of the tool base material is lowered. A second hard carbon layer forming step of forming a second hard carbon layer on the first hard carbon layer by applying the method to part or all of the base material. Thereby, peeling of the coating is suppressed and high wear resistance is obtained without requiring roughening treatment on the surface of the tool base material.
Further, according to the composite hard carbon coating of the second invention, the first hard carbon layer has a thickness of 0.2 μm to 3.0 μm and a density of 2.1 g/cm3 to 2.4 g/cm3, The second hard carbon layer has a thickness of 1.0 μm to 9.0 μm and a density of 2.5 g/cm 3 to 3.0 g/cm 3 . From this, the density of the first hard carbon layer on the tool base material side is relatively lower than the density of the second hard carbon layer thereon, so even if the hardness and thickness of the entire coating are increased, Since the first hard carbon layer, which has a relatively low density, functions as a buffer layer, peeling of the coating is suppressed as a whole, and high abrasion resistance is achieved.

The gist of the third invention is that the total thickness of the first hard carbon layer and the second hard carbon layer is 2 to 12 μm. Due to the thickness of the entire coating, even if the hardness and thickness are increased, the first hard carbon layer, which has a relatively low density, functions as a buffer layer, so peeling of the coating as a whole is suppressed and high wear resistance is achieved. Provides wear resistance.

The gist of the fourth invention is that the first hard carbon layer and the second hard carbon layer are alternately cleaned. Thereby, even if the upper pair of the hard carbon layer and the second hard carbon layer out of the plurality of laminated pairs is worn out, the coating will not peel off.

The gist of the fifth invention is that the first hard carbon layer and the second hard carbon layer are a mixed layer of ultra-nano microcrystalline diamond of 1 nm or more and 20 nm or less and amorphous carbon. As a result, higher hardness can be obtained compared to a carbon coating made of amorphous carbon, so the durability of the coating can be improved.

The gist of the sixth invention is that the composite hard carbon film does not substantially contain hydrogen and has a film hardness of 50 GPa or more as measured using a nanoindentation method. As a result, a tool with high wear resistance and durability can be obtained.

The gist of the seventh invention is a method for manufacturing a composite hard coating tool coated with a composite hard carbon coating, which comprises: in a vacuum chamber, in an ultra-high vacuum substantially free of hydrogen; Using a coaxial arc plasma gun that discharges between a cylindrical anode electrode and a cathode electrode made of graphite coaxially arranged within the cylindrical anode electrode, plasma is emitted from an opening at the tip of the cylindrical anode electrode. Formation of a first hard carbon layer by applying high-energy plasma particles to part or all of the tool base material to form a first hard carbon layer on the tool base material, which is an iron-based material or a superalloy material. and in the vacuum chamber, in an ultra-high vacuum that does not substantially contain hydrogen, in a temperature setting state where the temperature of the tool base material is lower than that of the first hard carbon layer forming step, the coaxial arc is The first hard carbon layer is formed by applying high-energy plasma particles to part or all of the tool base material using a plasma gun or a coaxial arc plasma gun different from the coaxial arc plasma gun. a second hard carbon layer forming step of forming a second hard carbon layer on the tool base material, and part or all of the tool base material is covered with the composite hard carbon coating. As a result, part or all of the tool base material is covered with the composite hard carbon coating, so peeling of the coating is suppressed and a composite hard carbon coating coated tool having high wear resistance is obtained.

1 is a front view showing a drill in which a composite hard carbon coating tool according to an embodiment of the present invention is adhered to the surface of a cutting part. FIG. 2 is an enlarged bottom view of the drill shown in FIG. 1 from its tip side for explaining the drill. FIG. 2 is an enlarged sectional view illustrating the laminated structure of a composite hard carbon coating deposited on the tool base material of the drill of FIG. 1; FIG. 2 is a schematic diagram illustrating the configuration of a coaxial vacuum arc deposition apparatus for forming the composite hard carbon coating of FIG. 1 on a tool base material. 6 is a schematic diagram illustrating the configuration of a coaxial arc plasma gun used in the coaxial vacuum arc deposition apparatus of FIG. 5. FIG. FIG. 5 is a diagram illustrating a film forming process of coating the composite hard carbon film of FIG. 3 on the surface of a tool base material using the coaxial vacuum arc deposition apparatus of FIG. 4; It is a chart showing the hardness and wear resistance evaluation results for a total of 17 types of samples, including Example Products 1 to 10 of the present invention and Comparative Example Products 1 to Comparative Example Products 7. 4 is a comparison table illustrating the difference between the coating structure of the embodiment shown in FIG. 3 and the coating structure described in Patent Document 2 and the like. FIG. 4 is an enlarged cross-sectional view illustrating a laminated structure of a composite hard carbon coating deposited on a tool base material in another embodiment of the present invention, and is a view corresponding to FIG. 3. FIG. 4 is an enlarged cross-sectional view illustrating a laminated structure of a composite hard carbon coating deposited on a tool base material in another embodiment of the present invention, and is a view corresponding to FIG. 3.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the composite hard carbon coating tool of the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are views showing a drill 10 which is an example of a composite hard carbon coated tool of the present invention. FIG. 1 is a front view seen from a direction perpendicular to the axis O, and FIG. 2 is an enlarged bottom view seen from the tip side where the cutting edge 12 is provided. The drill 10 includes a tool base material 22 made of a ferrous material such as high-speed tool steel (HSS) or a cemented carbide material. This drill 10 is a two-blade twist drill, and includes a shank 14 and a body 16 that are integrated in the axial direction, and the body 16 has a pair of grooves 18 that are twisted clockwise around the axis O. . A pair of cutting edges 12 are provided at the tip of the body 16 in correspondence with the grooves 18, and when viewed from the shank 14 side, the cutting edges 12 cut a hole by rotating clockwise around the axis O. While machining, chips are discharged through the groove 18 to the shank 14 side. In FIG. 1, the shaded area indicates the area coated with the composite hard carbon film 24. In this embodiment, the body 16, which is a part of the drill 10, is coated, but the entire drill 10 may be coated.

FIG. 3 is an enlarged view showing a cross section near the surface of the body 16, and the surface of the tool base material 22 that has not been roughened is coated with a composite hard carbon film 24. The composite hard carbon coating 24 includes a first hard carbon layer 26 directly deposited on the surface of the tool base material 22 and a first hard carbon layer deposited directly on the surface of the first hard carbon layer 26. A second hard carbon layer 28 having a higher density than the carbon layer 26 is constructed by being laminated in this order. The outermost layer of the composite hard carbon coating 24 is composed of a second hard carbon layer 28 having a relatively higher density than the first hard carbon layer 26 .

The first hard carbon layer 26 has a thickness t1 (0.2 μm≦t1≦3.0 μm) of 0.2 μm to 3.0 μm, and a density d1 (2.1 g/cm ³ to 2.4 g/cm ³ ). 1g/cm ³ ≦d1≦2.4g/cm ³ ). ^The second hard carbon layer 28 has a thickness t2 (1.0 μm≦t2≦9.0 μm) of 1.0 μm to 9.0 μm and a density ^d2 (2 .5g/cm ³ ≦d2≦3.0g/cm ³ ).

FIG. 4 is a schematic configuration diagram (schematic diagram) illustrating a coaxial vacuum arc deposition apparatus 30 used for manufacturing the drill 10. The coaxial vacuum arc evaporation apparatus 30 includes a workpiece holder 32, a temperature control device 36, a rotation device 38, a vacuum chamber 40 serving as a processing container that houses a tool base material 22, etc., and an exhaust device 42. A plurality of coaxial arc plasma guns, in this embodiment, a pair of first coaxial arc plasma gun 44 and second coaxial arc plasma gun 46, and the first coaxial arc plasma gun 44 are driven to emit arc plasma from the tip. A first arc power source 48 for emitting, a second arc power source 50 for driving the second coaxial arc plasma gun 46 to emit high-energy plasma particles from the tip, and setting the potential of the tool base material 22 to the ground potential. The tool includes a bias power source 52 that applies a bias voltage higher than E to the tool base material 22.

The workpiece holder 32 holds a tool base material 22 in which cutting edges 12, grooves 18, etc. are formed before coating a large number of workpieces, that is, a composite hard carbon coating 24, with the tip of the tool base material 22 protruding outward. It holds the shank 14 of the tool base material 22. The temperature control device 36 controls the temperature of the tool base material 22 by adjusting the sheathed heater 34 that heats the tool base material 22 held by the workpiece holder 32 and the drive current of the sheathed heater 34 . The exhaust device 42 exhausts the gas in the vacuum chamber 40 using a vacuum pump or the like to reduce the pressure to an ultra-high vacuum higher than about 10 ⁻⁵ Pa, and brings the inside of the vacuum chamber 40 into an ultra-high vacuum state substantially free of hydrogen. do. The rotation device 38 rotates the workpiece holder 32 about its substantially vertical rotation center line.

In the coaxial vacuum arc deposition apparatus 30, the film forming operation is performed periodically in synchronization with the repeated charging and discharging of the capacitor C, so the number of charging and discharging of the capacitor C can be controlled without using a cathode shutter or a substrate shutter. By setting, the thickness of the carbon film deposited on the tool base material 22 can be controlled to a desired value. Furthermore, since the coaxial vacuum arc deposition apparatus 30 does not use gas to generate electrons, it is possible to form a highly pure amorphous carbon film (DLC) under an ultra-high vacuum of less than about 10 ⁻⁵ Pa. In addition, since the ionization rate of the plasma is as high as about 80% and the kinetic energy of the particles is high, a dense hard carbon film with good adhesion can be formed. The first hard carbon layer 26 and the second hard carbon layer 28 are hard carbon films, and are a type of hard carbon film such as diamond-like carbon (DLC). Ultra-nano microcrystalline diamond (UNCD) is contained because microscopic carbon vapor (carbon ions) having an electric charge are emitted from the cylindrical anode electrode AE without being emitted from the anode electrode AE. To be precise, it is a mixed phase film (UNCD/aC film) of several nano-sized diamond crystals (UNCD) and amorphous carbon (aC).

The first coaxial arc plasma gun 44 and the first arc power supply 48 that drives it, and the second coaxial arc plasma gun 46 and the second arc power supply 50 that drives it are configured in exactly the same way, so they are common. The configurations of the first coaxial arc plasma gun 44 and the first arc power source 48 will be representatively explained using FIG. 5. In the first coaxial arc plasma gun 44, the solid target constituting the cathode electrode KE is pure graphite for forming the first hard carbon layer 26 and the second hard carbon layer 28, which are undoped carbon films.

As shown in FIG. 5, the first coaxial arc plasma gun 44 includes a cylindrical cathode electrode KE that is a solid target made of graphite, a cylindrical insulator CE that is an insulator that holds the outside of the cylindrical cathode electrode KE, and a cylindrical insulator CE that is an insulator that holds the outside of the cylindrical cathode electrode KE. It has a cylindrical trigger electrode TE attached to the tip of the trigger electrode TE. In the first coaxial arc plasma gun 44, the trigger electrode TE is attached to the outer periphery of the cylindrical insulator CE, and the cathode electrode KE is inserted into the cylindrical insulator CE. An inner electrode assembly assembled concentrically is arranged concentrically within a cylindrical anode electrode AE having a larger diameter than the inner electrode assembly. The first arc power source 48 includes an arc power source AS connected between the cathode electrode KE and the earth potential E, a trigger power source TS connected between the cathode electrode KE and the trigger electrode TE, and an arc power source TS connected between the cathode electrode KE and the earth potential E. and a capacitor C connected between the potential E and the capacitor C.

FIG. 6 is a diagram illustrating a film forming process of coating the composite hard carbon film 24 on the surface of the tool base material 22 using the coaxial vacuum arc deposition apparatus 30. In FIG. 6, in the first coaxial arc plasma gun 44 configured as described above, electrons are generated by creeping discharge from the trigger electrode TE, and using this as an opportunity, the electric charge charged in the capacitor C is discharged at once to the cathode electrode KE. Then, graphite, which is a solid target constituting the cathode electrode KE, is liquefied, vaporized, and turned into plasma, and high-energy plasma particles P are scattered toward the tool base material 22 from the tip opening of the cylindrical anode electrode AE. , is applied to the surface of the tool base material 22. In this way, the first hard carbon layer 26 is formed by driving the second coaxial arc plasma gun 46 at the same time as the first coaxial arc plasma gun 44 is driven. In the first hard carbon layer forming step P1 of forming the first hard carbon layer 26 on the tool base material 22, the workpiece holder 32 is maintained at a predetermined film forming temperature and a predetermined bias voltage. It is performed by rotating around the center line of rotation at a constant rotational speed. The film forming conditions in this first hard carbon layer forming step P1 are that the thickness t1 of the first hard carbon layer 26 is from 0.2 μm to 3.0 μm (0.2 μm≦t1≦3.0 μm), and the density d1 is as follows. It is set to be 2.1 g/cm ³ to 2.4 g/cm ³ (2.1 g/cm ³ ≦d1≦2.4 g/cm ³ ).

Next, in the second hard carbon layer forming step P2, the workpiece holder 32 in the first hard carbon layer forming step P1 is the same as the first hard carbon layer except that the film forming temperature is lower than the predetermined film forming temperature. Similarly to the carbon layer forming step P1, the second hard carbon layer 28 is formed by driving the first coaxial arc plasma gun 44 and simultaneously driving the second coaxial arc plasma gun 46. In the second hard carbon layer forming step P2 of forming the second hard carbon layer 28 on the tool base material 22, the thickness t2 of the second hard carbon layer 28 is from 1.0 μm to 9.0 μm (1.0 μm≦t2 ≦9.0 μm), and the density d2 is set to be from 2.5 g/cm ³ to 3.0 g/cm ³ (2.5 g/cm ³ ≦d2 ≦3.0 g/cm ³ ). Performed under membrane conditions.

FIG. 7 is a chart showing the hardness and abrasion resistance evaluation results for a total of 17 types of samples, Example Product 1 to Example Product 10 and Comparative Example Product 1 to Comparative Example Product 7. These 17 types of samples were made using pellet-shaped specimens made of cemented carbide or high-speed tool steel (HSS) with a diameter of 10 mm and a thickness of 5 mm, and had a two-layer film structure similar to that shown in Fig. 3. Alternatively, a film configuration of four or more layers similar to that shown in FIG. 10, which will be described later, is manufactured so that the film thicknesses of the layers are different from each other. Figure 7 shows the base material, type of composite hard carbon coating layer, layer thickness (μm), layer density (g/cm ³ ), total film thickness (μm), and film thickness for these 17 types of samples. The structure, interlayer structure, hydrogen content (at%), diamond crystal size (nm), film hardness (GPa), and wear volume (μm ³ ) in the wear test, which is the evaluation result, are shown.

Below, a method for producing the above test piece, a method for measuring thickness and hardness, and an evaluation method will be explained.

(Measurement of film thickness)
Observe the secondary electron image (SEM) of the cross section of the test piece using a scanning electron microscope, and based on the film thickness dimension obtained from the secondary electron image and the magnification of the secondary electron image. The film thickness was measured.

(Measurement of film density)
Measured using the float-sink method. In other words, two types of liquids with clearly different densities were mixed, and a mixed liquid was prepared in which the sample to be measured (powdered film peeled off from a pellet-like test piece) neither rose nor sank. . Then, the density of the mixed liquid was measured, and the density of the specific object was identified from the measured density.

(Measurement of hydrogen content)
Using the elastic recoil particle detection method, the hydrogen content (at%) contained in the composite hard carbon coating 24 was measured using SIMS analysis and ERDA analysis under the measurement conditions shown below.
○SIMS (Secondary Ion Mass Spectrometry) analysis conditions ・Measurement device: SIMS analysis (Secondary Ion Mass Spectrometry)
・Primary ion species: Cs ⁺
・Primary ion beam irradiation energy: 5.5 MeV
・Measurement secondary ion characteristics: Positive ions (CsM+ method)
・Measurement elements: H and C (matrix monitor)
○ERDA (Elastic Recoil Detection Analysis) analysis conditions ・Analysis type: ERDA (HFS, forward scattering)
・Ion species of incident ion beam: He ⁺⁺
・Energy of incident ion beam: 2.275MeV
・Normal detector angle: 160°
・Glazing detector angle: 30°
・Angle of incident ion beam with respect to sample normal: 75°

First, in the SIMS analysis described above, an energetic and focused primary ion beam is scanned and irradiated onto an area of 150 μm x 150 μm on the sample surface, and the generated secondary ions are detected by mass separation, and the depth of the sample is determined. The concentration distribution of hydrogen H and carbon C in the direction was measured. Next, the total amount of hydrogen in the analysis results using the above ERDA analysis is taken as the known concentration, and the relative sensitivity factor (RSF) is derived from the SIMS analysis measurement data of this sample to determine the hydrogen concentration (at%). Conversion was carried out. Quantification of hydrogen concentration using HFS (Hydrogen Forward Scattering) involves determining the material stopping power of two standard samples (muscovite and a Si wafer implanted with hydrogen ions) and an actual sample, each of which has a known hydrogen concentration. After normalization, concentration conversion was performed by comparing the normalized hydrogen intensities. The above-mentioned stopping power refers to the degree of energy that a certain type of charged particle loses due to ionization or excitation of the material's atoms when a certain type of charged particle passes through the material, and is called the stopping power of that material for that charged particle. Here, for concentration conversion in SIMS analysis, it is assumed that the hydrogen concentration determined by HFS analysis of a sample containing a certain amount (for example, 10 at% or more) of hydrocarbon gas matches the ionic strength Ip in SIMS, and the relative After deriving the sensitivity factor (RSF), the hydrogen concentration Cr (Cr=Ip×RSF) of each sample was determined by multiplying the calculated relative sensitivity factor (RSF) by the ionic strength of the measurement sample.

(Measurement of diamond crystal size)
The measurement was performed by a known method using a lattice image obtained by a transmission electron microscope.

(Measurement and evaluation of film hardness)
The measurement was performed using a thin film hardness meter that complies with the ISO standard "ISO14577-4:2016". That is, the hardness of the composite hard carbon coating 24, more precisely, the hardness of the second hard carbon layer 28, was measured using the nanoindentation method specified in the ISO standard "ISO14577-4:2016" under the measurement conditions shown below. It was measured. Those with a measured coating hardness of 50 GPa or more were judged to be acceptable.
○Measurement conditions/test load: 5mN
・Load arrival time: 10sec.
・Load holding time: 5sec.
・Unloading time: 10sec.
・Test location: 10 points

(Measurement and evaluation of wear resistance)
Fourteen types of cylindrical test pieces were fabricated on a partially spherical surface formed at one end of a pin-shaped cylindrical test piece, each having a two-layer film structure similar to the pellet-like test piece, but with different film thicknesses. Then, the film formed on the partial spherical surface at one end of each of these cylindrical test pieces was abraded under certain conditions using the test method shown below, and the abrasion volume of the cylindrical test piece was calculated as shown below. Measured using the measurement method. Those with a measured abrasion volume of 60,000 μm ³ or less or no peeling were judged to be acceptable.
○Abrasion test conditions ・Cylindrical test piece: length 25mm, diameter 6mm, radius of curvature of partial sphere 5mm
・Abrasion tester: Pin-on-disk friction and wear tester (FPR-2100 manufactured by RHESCA)
・Material of friction disk: Al ₂ O ₃
・Load: 300g
・Linear speed: 200mm/sec.
・Test (friction) time: 10 min.
○Method for measuring the amount of friction - Laser microscope (LEXT OLS4100 manufactured by OLYMPUS)
The wear depth (μm) of the three-dimensionally measured wear circle is calculated for each scan using the confocal optical system of the laser microscope and laser scanning, and the wear volume (μm ³ ) is calculated from the wear depth for each scan. Calculated.

In FIG. 7, Examples 1 to 10 all had a coating hardness (second hard carbon layer 28) of 50 GPa or more, a wear volume of 60,000 μm ³ or less, and no peeling. On the other hand, in Comparative Examples 1 to 7, the coating hardness was less than 50 GPa, the abrasion volume was more than 60,000 μm ³ , or peeling occurred. As shown in FIG. 7, the samples shown in Example Products 1 to 10 are included in the present invention, and have a thickness t1 ranging from 0.2 μm to 3.0 μm (0.2 μm≦t1≦3.0 μm). ) and a density d1 in the range of 2.1 g/cm ³ to 2.4 g/cm ³ (2.1 g/cm ³ ≦d1 ≦2.4 g/cm ³ ); Thickness t2 in the range of 0 μm to 9.0 μm (1.0 μm≦t2≦9.0 μm) and density d2 in the range of 2.5 g/cm ³ to 3.0 g/cm ³ (2.5 g/cm ³ ≦d2 3.0 g/cm ³ ).

On the other hand, in Comparative Example Product 1, the thickness t1 of the first hard carbon layer is less than 0.2 μm, which is the lower limit of the above range, and the density d1 is 2.4 g/cm, which is the upper limit of the above range. It exceeds ³ . In Comparative Example Product 2, the density d2 of the second hard carbon layer exceeds the upper limit of 3.0 g/cm ³ in the above range. In Comparative Example Product 3, the density d1 of the first hard carbon layer is below the lower limit of 2.1 g/cm ³ in the above range. In Comparative Example Product 4, the thickness t1 of the first hard carbon layer exceeds the upper limit of 3.0 μm in the above range, and the thickness t2 of the second hard carbon layer falls below the lower limit of 1.0 μm in the above range. There is. In Comparative Example Product 5, the thickness t2 of the second hard carbon layer exceeds the above range of 9.0 μm, and the density d2 is below the lower limit of 2.5 g/cm ³ of the above range. In Comparative Example Product 6, the density d1 of the first hard carbon layer exceeds the upper limit of 2.4 g/cm ³ in the above range, and the thickness t2 of the second hard carbon layer is below 1.0 μm in the above range. . In Comparative Example Product 7, the density d1 of the first hard carbon layer exceeds the upper limit of the above range of 2.4 g/cm ³ .

FIG. 8 is a comparison table illustrating the difference between the composite hard carbon coating 24 having the first hard carbon layer 26 and the second hard carbon layer 28 of the example and the hard coating described in Patent Document 2 and the like. As shown in FIG. 8, the composite hard carbon coating 24 of the example is composed of a mixed phase of ultra-nano-microcrystalline diamond and amorphous carbon, compared to the ultra-nano-microcrystalline diamond coating described in Patent Document 2. They have one thing in common: However, the composite hard carbon coating 24 of the example does not substantially contain hydrogen, has a hardness of 50 GPa or more, has a large thickness, and has a density higher than that of the first hard carbon layer 26. The difference is that a second hard carbon layer 28 is provided. The ultra-nano microcrystalline diamond coating described in Patent Document 2 is intended to be applied to the surfaces of molds and cutting tools to increase their lifespan. On the other hand, since the composite hard carbon coating 24 of the embodiment has the above-mentioned differences, the density of the first hard carbon layer 26 on the tool base material 22 side is lower than that of the second hard carbon layer 26 thereon. Even if the hardness and thickness of the coating 24 as a whole are increased, the first hard carbon layer 26, which has a relatively low density, functions as a buffer layer, so that peeling of the coating as a whole is prevented. Therefore, high wear resistance can be obtained, and the wear resistance of the drill (composite hard carbon film coated tool) 10 can be suitably increased.

As described above, the composite hard carbon coating 24 of the drill (composite hard carbon coating coated tool) 10 of this embodiment includes the first hard carbon layer 26 deposited on the tool base material 22, and the first hard carbon layer 26 deposited on the tool base material 22. A second hard carbon layer 28 is included that is deposited over layer 26 and has a higher density than first hard carbon layer 26 . The first hard carbon layer 26 has a thickness t1 (0.2 μm≦t1≦3.0 μm) of 0.2 μm to 3.0 ^μm and a density ^d1 (2 .1g/ ^cm3 ≦d1≦2.4g/ ^cm3 ), and the second hard carbon layer 28 has a thickness t2 of 1.0 μm to 9.0 μm (1.0 μm≦t2≦9.0 μm). It has a density d2 of 2.5 g/cm ³ to 3.0 g/cm ³ (2.5 g/cm ³ ≦d2 ≦3.0 g/cm ³ ). From this, the density of the first hard carbon layer 26 on the tool base material 22 side is relatively smaller than the density of the second hard carbon layer 28 thereon, so the hardness and thickness of the entire coating can be increased. However, since the first hard carbon layer 26, which has a relatively low density, functions as a buffer layer, peeling of the coating is suppressed as a whole, and high wear resistance is obtained.

According to the composite hard carbon coating 24 of this example, the total thickness of the first hard carbon layer 26 and the second hard carbon layer 28 is from 2 to 12 μm. Due to the thickness of the entire coating, even if the hardness and thickness are increased, the first hard carbon layer 26, which has a relatively low density, functions as a buffer layer, so peeling of the coating as a whole is suppressed and high resistance is achieved. Provides abrasion resistance.

According to the composite hard carbon coating 24 of this example, the first hard carbon layer 26 and the second hard carbon layer 28 have a mixed phase of ultra-nano microcrystalline diamond of 1 nm or more and 20 nm or less and amorphous carbon in the film. . This provides higher hardness than a carbon coating made of simple amorphous carbon, thereby increasing the durability of the coating.

According to the composite hard carbon coating 24 of this example, the composite hard carbon coating 24 does not substantially contain hydrogen and has a coating hardness of 50 GPa or more as measured using the nanoindentation method. As a result, a drill (composite hard carbon coating tool) 10 having high wear resistance and durability is obtained.

According to the composite hard carbon coating 24 of this embodiment, the drill (composite hard carbon coating tool) 10 is provided in which part or all of the tool base material 22 is coated with the composite hard carbon coating 24. Thereby, peeling of the coating is suppressed, and a drill (composite hard carbon coating tool) 10 having high wear resistance is obtained.

According to the method for manufacturing the composite hard carbon coating 24 of this embodiment, (1) graphite is coaxially arranged between the cylindrical anode electrode AE and the cylindrical anode electrode AE in vacuum in the vacuum chamber 40; Using coaxial arc plasma guns 44 and 46 that discharge between the cathode electrode KE and the cathode electrode KE, high-energy plasma particles emitted from the opening at the tip of the cylindrical anode electrode AE are transferred to a part of the tool base material 22. or the first hard carbon layer forming step P1 in which the first hard carbon layer 26 is formed on the tool base material 22 by applying the first hard carbon layer to the entire tool base material 22; In a temperature setting state in which the temperature of the tool base material 22 is lower than that in the forming process P1, a discharge is caused between the cylindrical anode electrode AE and the cathode electrode KE made of graphite coaxially arranged in the cylindrical anode electrode AE. The coaxial arc plasma guns 44 and 46 are used to apply high-energy plasma particles emitted from the opening at the tip of the cylindrical anode electrode AE to part or all of the tool base material 22. A second hard carbon layer forming step P2 of forming a second hard carbon layer 28 on the hard carbon layer 26 is included. Thereby, peeling of the coating is suppressed and high wear resistance is obtained without requiring roughening treatment on the surface of the tool base material 22.

Next, another embodiment of the present invention will be described. In the following description, parts common to those in the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 9 is an enlarged sectional view illustrating the composite hard carbon coating 124 of the drill 110, which is a composite hard carbon coating coated tool according to another embodiment of the present invention. The boundary between the first hard carbon layer 26 and the second hard carbon layer 28 constituting the composite hard carbon coating 124 formed on the surface of the drill 110 of this embodiment is the boundary between the first hard carbon layer forming step P1 and the second hard carbon layer 28. The temperature of the tool base material 22 is continuously changed during the carbon layer forming step P2, resulting in a gradient structure in which the density is continuously changed. Thereby, delamination between the first hard carbon layer 26 and the second hard carbon layer 28 is suitably suppressed.

FIG. 10 is an enlarged sectional view illustrating a composite hard carbon coating 224 of a drill 210, which is a composite hard carbon coating tool according to another embodiment of the present invention. The composite hard carbon coating 224 formed on the surface of the drill 210 of this embodiment has a first hard carbon layer 26 and a second hard carbon layer 28 laminated alternately, and a first hard carbon layer 22 is formed on the tool base material 22 side. A carbon layer 26 is formed, and a second hard carbon layer 28 is formed on the surface layer side, resulting in a structure of four or more layers. Thereby, even if the layered pair of the second hard carbon layer 28 and the first hard carbon layer 26 of the surface layer is worn out, peeling of the coating is suppressed and the durability of the drill 210 is increased.

Although one embodiment of the present invention has been described above based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the embodiments described above, the composite hard carbon coatings 24, 124, 224 were applied to the drills 10, 110, 210, but the composite hard carbon coatings 24, 124, 224 are applied not only to drills but also to end mills, milling machines, etc. It can be applied to various processing tools such as cutting tools such as cutting tools, build-up taps, rolling tools, non-cutting tools such as press dies, and various tool members such as friction parts that require wear resistance. .

In addition, although the coaxial vacuum arc deposition apparatus 30 described above was provided with two first coaxial arc plasma guns 44 and a second coaxial arc plasma gun 46, it may be one, or three or more. It may be.

Also, for example, the first coaxial arc plasma gun 44 may be used exclusively to form the first hard carbon layer 26 and the second coaxial arc plasma gun 46 may be used exclusively to form the second hard carbon layer 28.

Although the embodiments of the present invention have been described above in detail based on the drawings, these are just one embodiment, and the present invention can be implemented with various changes and improvements based on the knowledge of those skilled in the art. can do.

10, 110, 210: Drill (composite hard carbon coating tool)
22: Tool base material 24, 124, 224: Composite hard carbon coating 26: First hard carbon layer 28: Second hard carbon layer 40: Vacuum chamber 44: First coaxial arc plasma gun (coaxial arc plasma gun)
46: Second coaxial arc plasma gun (coaxial arc plasma gun)
KE: Cathode electrode AE: Anode electrode

Claims (7)

A method for manufacturing a composite hard carbon coating, the method comprising:
A coaxial arc plasma gun that generates a discharge between a cylindrical anode electrode and a graphite cathode electrode disposed coaxially within the cylindrical anode electrode in an ultra-high vacuum substantially free of hydrogen in a vacuum chamber. By applying high-energy plasma particles emitted from the opening at the tip of the cylindrical anode electrode to part or all of the tool base material, the first hard carbon is deposited on the tool base material. a first hard carbon layer forming step of forming a layer;
In the vacuum chamber, in an ultra- high vacuum that does not substantially contain hydrogen, in a temperature setting state in which the temperature of the tool base material is lower than in the first hard carbon layer forming step, the coaxial arc plasma gun; Alternatively, a coaxial arc plasma gun different from the coaxial arc plasma gun may be used to apply high-energy plasma particles to part or all of the tool base material, thereby forming a carbon layer on the first hard carbon layer. a second hard carbon layer forming step of forming a second hard carbon layer;
A method for producing a composite hard carbon film, characterized by: The first hard carbon layer has a thickness of 0.2 μm to 3.0 μm and a density of 2.1 g/cm ³ to 2.4 g/cm ³ ,
The composite hard carbon coating according to claim 1, wherein the second hard carbon layer has a thickness of 1.0 μm to 9.0 μm and a density of 2.5 g/cm ³ to 3.0 g/cm ³ . Production method. The method for manufacturing a composite hard carbon coating according to claim 2 , wherein the total thickness of the first hard carbon layer and the second hard carbon layer is 2 to 12 μm. The method for manufacturing a composite hard carbon coating according to claim 2 or 3, wherein the composite hard carbon coating includes the first hard carbon layer and the second hard carbon layer stacked alternately. The composite hard carbon layer according to any one of claims 2 to 4, wherein the first hard carbon layer and the second hard carbon layer are a mixed phase of ultra-nano microcrystalline diamond of 1 nm or more and 20 nm or less and amorphous carbon. Method for producing carbon film. The composite hard carbon coating according to any one of claims 2 to 5, wherein the composite hard carbon coating substantially does not contain hydrogen and has a coating hardness of 50 GPa or more as measured using a nanoindentation method. Method of manufacturing the coating. A method for manufacturing a composite hard coating tool having a composite hard carbon coating applied thereto , the method comprising:
A coaxial arc plasma gun that generates a discharge between a cylindrical anode electrode and a graphite cathode electrode disposed coaxially within the cylindrical anode electrode in an ultra-high vacuum substantially free of hydrogen in a vacuum chamber. By applying high-energy plasma particles emitted from the opening at the tip of the cylindrical anode electrode to part or all of the tool base material, the tool is made of iron-based material or superalloy material. a first hard carbon layer forming step of forming a first hard carbon layer on the base material;
In the vacuum chamber, in an ultra- high vacuum that does not substantially contain hydrogen, in a temperature setting state in which the temperature of the tool base material is lower than in the first hard carbon layer forming step, the coaxial arc plasma gun; Alternatively, a coaxial arc plasma gun different from the coaxial arc plasma gun may be used to apply high-energy plasma particles to part or all of the tool base material, thereby forming a carbon layer on the first hard carbon layer. a second hard carbon layer forming step of forming a second hard carbon layer,
A method for manufacturing a composite hard carbon coating tool, characterized in that part or all of the tool base material is coated with the composite hard carbon coating.

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