Diamond Coated Tools

Abstract

A substrate made of a tungsten carbide-based cemented carbide and a WC substrate having a composition represented by the following formula 1 provided directly on the substrate. x Layers and Formula 1:WC x In the formula 1, x is 0.27 or more and 0.67 or less, The WC x and a diamond layer disposed directly on the layer.

Description

[Technical Field]

[0001] The present disclosure relates to diamond coated tools. [Background technology]

[0002] Diamond is extremely hard, and its smooth surface has an extremely low coefficient of friction. Since the technology for forming diamond thin films using chemical vapor deposition (CVD) was established in the 1980s, diamond-coated tools have been developed, in which a diamond layer is formed on a three-dimensional substrate.

[0003] When a cemented carbide is used as the substrate, cobalt, which is a binder phase component of the cemented carbide, diffuses to the diamond side and reacts with the diamond during vapor phase synthesis of the diamond layer, resulting in insufficient formation of the diamond layer.

[0004] Japanese Patent Laid-Open Publication No. 2010-17791 (Patent Document 1) discloses a diamond-coated cemented carbide cutting tool in which a tungsten carbonitride layer is provided between the substrate and the diamond layer in order to suppress the diffusion of cobalt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-17791 Summary of the Invention

[0006] The diamond-coated tool of the present disclosure comprises a substrate made of a tungsten carbide-based cemented carbide, and a WC (WO) layer having a composition represented by the following formula 1 provided directly on the substrate: x Layers and Formula 1:WC x In the formula 1, x is 0.27 or more and 0.67 or less, The WC x and a diamond layer disposed directly on the layer. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic enlarged cross-sectional view of an example of a diamond-coated tool according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram of an example of a diamond-coated tool according to the first embodiment. [Figure 3] FIG. 3 is a schematic view of an SEM image of a cross-sectional sample of the diamond-coated tool according to the first embodiment. [Figure 4] FIG. 4 is an example of a first graph obtained with the diamond-coated tool according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Problem to be solved by this disclosure] When cutting is performed using the diamond-coated cemented carbide cutting tool of Patent Document 1, the diamond layer tends to peel off, shortening the tool life. As a result of extensive research into the cause of diamond layer peeling, the present inventors have found that the structure of the layer located between the tungsten carbide-based cemented carbide and the diamond layer affects the crystallinity of the diamond layer located immediately above, the cobalt diffusion suppression effect, and the formation of a diffusion layer with the diamond layer, thereby reducing the adhesion of the diamond layer and causing peeling.

[0009] There is a demand for diamond-coated tools that are less susceptible to diamond peeling during cutting and have a long tool life.

[0010] The present disclosure aims to provide a diamond coated tool having a long tool life.

[0011] [Effects of this disclosure] According to the present disclosure, it is possible to provide a diamond coated tool having a long tool life.

[0012] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. (1) The diamond-coated tool of the present disclosure comprises a substrate made of a tungsten carbide-based cemented carbide and a WC (WO) layer having a composition represented by the following formula 1, provided directly on the substrate: x Layers and Formula 1:WC x In the formula 1, x is 0.27 or more and 0.67 or less, The WC x and a diamond layer disposed directly on the layer.

[0013] According to the present disclosure, it is possible to provide a diamond-coated tool having a long tool life, and the reason for this is presumably as follows.

[0014] In the diamond-coated tool of the present disclosure, WC is interposed between the substrate and the diamond layer. x Layers are provided. x When the layer x is 0.27 or more, WC x The amount of metallic tungsten in the layer that does not form carbides is reduced. x The more metallic tungsten in the layer, the greater the WC x The linear expansion coefficient of the diamond layer and the WC layer increases. x The strength of the interface between the WC layer and the diamond layer decreases, the diamond layer becomes more susceptible to peeling, and the tool life of the diamond-coated tool decreases. x The amount of metallic tungsten in the layer is reduced, so the diamond layer and WC x The adhesion between the layers is improved.

[0015] In the diamond coated tool of the present disclosure, WC x By setting x of the layer to 0.67 or less, the crystal mismatch with the diamond is suppressed, the crystallinity of the diamond layer is good, and the diamond layer and WC x The adhesion between the layers is improved.

[0016] (2) In the above (1), the Raman shift of the Raman spectrum of the diamond layer is 1200 cm -1 More than 1700cm -1 In the following range, the ratio Id / Is of the diamond peak area intensity Id to the area intensity Is of the entire spectrum is 2 × 10 -3 5x10 or more -2 The following is also acceptable.

[0017] This further improved the crystallinity of the diamond layer, and the diamond layer and WC x The adhesion between the diamond layer and the diamond layer is further improved. Furthermore, the wear resistance and strength of the diamond layer are improved.

[0018] (3) In the above (1) or (2), the WC x The WC layer is then heated to a temperature of 1000° C. from the interface between the WC layer and the diamond layer. x The cobalt content of a first region sandwiched between a first imaginary plane that is 30 nm away from the interface toward the diamond layer and a second imaginary plane that is 30 nm away from the interface toward the diamond layer may be 1.9 atomic % or less. The cobalt content is measured by performing line analysis on a cross section of the diamond-coated tool taken along the normal to the main surface of the diamond layer using an energy dispersive X-ray spectrometer attached to a scanning transmission electron microscope.

[0019] When the cobalt content of the first region is 1.9 atomic % or less, the reaction between cobalt and diamond is suppressed during vapor phase synthesis of the diamond layer, and the diamond layer and WC x The adhesion between the layers is further improved.

[0020] (4) In any of the above (1) to (3), the WC x The WC layer is then heated to a temperature of 1000° C. from the interface between the WC layer and the diamond layer. x The first region sandwiched between a first imaginary plane at a distance of 30 nm from the interface toward the diamond layer side and a second imaginary plane at a distance of 30 nm from the interface toward the diamond layer side has a tungsten atom number N W Number of carbon atoms N C Ratio of N C / NW is 0.27 or more and 4.0 or less, and the N of the carbon diffusion layer C / N W The average of N may be greater than x in the formula 1, and the thickness of the carbon diffusion layer may be 5 nm or more and 30 nm or less. C / N W is measured by performing a line analysis on a cross section of the diamond coated tool along the normal to the main surface of the diamond layer using an energy dispersive X-ray spectrometer attached to a scanning transmission electron microscope.

[0021] The carbon diffusion layer, which is 5 nm to 30 nm thick, separates the diamond layer and the WC layer. x The adhesion between the layers is further improved.

[0022] (5) In any of the above (1) to (4), the WC x The arithmetic mean roughness Ra of the main surface of the layer on the diamond layer side may be 0.1 μm or more and 1.0 μm or less. When the arithmetic mean roughness Ra is 0.1 μm or more, the diamond layer and the WC layer are bonded to each other by an anchor effect. x When the arithmetic mean roughness Ra is 1.0 μm or less, the adhesion strength with the WC layer is further improved. x In the initial stage of growth when growing a diamond layer on the layer, bonding between diamond grains after nucleation is promoted early, improving the adhesive strength of the diamond layer.

[0023] [Details of the embodiments of the present disclosure] Specific examples of the diamond-coated tool of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for the sake of clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0024] In the present disclosure, the notation in the form "A to B" means greater than or equal to A and less than or equal to B, and when no unit is specified for A and only a unit is specified for B, the unit of A and the unit of B are the same.

[0025] In the present disclosure, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is intended to include any conventionally known atomic ratio, and should not necessarily be limited to only those within the stoichiometric range.

[0026] In this disclosure, when one or more numerical values ​​are listed as the lower limit and upper limit of a numerical range, the combination of any one numerical value listed in the lower limit and any one numerical value listed in the upper limit is also disclosed.

[0027] In this disclosure, "comprises," "includes," "has," and variations thereof are open-ended terms. Open-ended terms may or may not include additional elements in addition to the required elements. The term "consisting of" is closed-ended. However, even a configuration expressed in closed terms may include additional elements that are normally incidental impurities or unrelated to the subject technology.

[0028] [Embodiment 1: Diamond coated tool] As shown in FIG. 1, a diamond-coated tool 10 according to one embodiment of the present disclosure (hereinafter also referred to as "embodiment 1") includes a substrate 1 made of a tungsten carbide-based cemented carbide, and a WC-based ... x Layer 2 and Formula 1:WC x In Formula 1, x is equal to or greater than 0.27 and equal to or less than 0.67, WC x and a diamond layer 3 disposed directly on the layer 2.

[0029] The diamond-coated tool of embodiment 1 can be, for example, a drill, an end mill, an indexable cutting tip for a drill, an indexable cutting tip for an end mill, an indexable cutting tip for a milling cutter, an indexable cutting tip for a turning cutter, a metal saw, a gear cutting tool, a reamer, a tap, etc. Fig. 2 is a schematic diagram of an example of a diamond-coated tool. The diamond-coated tool 10 is an indexable cutting tip and has a cutting edge ridge 11.

[0030] <Base material> In the diamond-coated tool of embodiment 1, a conventionally known tungsten carbide-based cemented carbide alloy can be used as the substrate. The tungsten carbide-based cemented carbide alloy may contain tungsten carbide particles and cobalt. The cemented carbide alloy may have a tungsten carbide particle content of 77% by mass or more and 96% by mass or less. The cemented carbide alloy may have a cobalt content of 3% by mass or more and 15% by mass or less. The total content of the tungsten carbide particles and cobalt in the cemented carbide alloy may be 80% by mass or more and 98% by mass or less. The cemented carbide alloy may contain other components in addition to tungsten carbide and cobalt. The other components may include at least one selected from the group consisting of Ni, Fe, TiC, ZrC, HfC, VC, NbC, TaC, Cr3C2, Mo2C, TiN, and ZrN. The content of the other components in the cemented carbide alloy may be 20% by mass or less.

[0031] The average particle size of the tungsten carbide particles is not particularly limited. The diamond-coated tool of embodiment 1 can have a long tool life regardless of the average particle size of the tungsten carbide particles. The average particle size of the tungsten carbide particles may be 0.1 μm or more and 5.0 μm or less, 0.2 μm or more and 4.5 μm or less, or 0.3 μm or more and 4.0 μm or less.

[0032] The average particle size of tungsten carbide particles is measured as follows: In a cross section of the cemented carbide, the circle-equivalent diameter (Heywood diameter: diameter equivalent to a circle with an equal area) of each tungsten carbide particle is measured, and the 50% cumulative particle size (circle-equivalent diameter) D50 based on these areas is calculated. This D50 corresponds to the average particle size of the tungsten carbide particles.

[0033] <WC x Layer> In the diamond-coated tool of embodiment 1, WC x The layer is applied directly onto the substrate. x The layer may be provided so as to cover the entire substrate. x The layer may cover at least a portion of the substrate that functions as a tool. In the present disclosure, the portion that functions as a tool means a portion that comes into contact with the object to be processed. For example, if the tool is a cutting tool, the portion that functions as a tool means a region within 0.5 μm from the cutting edge of the substrate. As long as the effect of the present disclosure is not impaired, WC x The layer may not cover a portion of the substrate.

[0034] ≪Composition≫ WC x The layer refers to tungsten carbide, where the atomic ratio of carbon (C) is x when the atomic ratio of tungsten (W) is 1. x The layer may contain unavoidable impurities as long as the effects of the present disclosure are not impaired. x The layer may contain unavoidable impurities in an amount of 0% by mass or more and 0.2% by mass or less, including boron, nitrogen, oxygen, iron, magnesium, and aluminum.

[0035] In the diamond-coated tool of embodiment 1, the x is 0.27 or more and 0.67 or less, and may be 0.28 or more and 0.65 or less, 0.30 or more and 0.60 or less, 0.33 or more and 0.59 or less, 0.34 or more and 0.58 or less, 0.39 or more and 0.56 or less, 0.40 or more and 0.53 or less, 0.41 or more and 0.50 or less, or 0.44 or more and 0.48 or less.

[0036] If the above x is less than 0.27, WC x The amount of metallic tungsten in the layer increases. x The higher the amount of metallic tungsten in the layer, the x The linear expansion coefficient of the diamond layer and the WC layer increases.x The strength of the interface between the diamond layer and the diamond coating layer decreases, the diamond layer becomes more susceptible to peeling, and the tool life of the diamond-coated tool decreases.

[0037] If the above x exceeds 0.67, WC x The layer becomes similar to the WC composition of general cemented carbide, causing a crystal mismatch with the diamond, and the crystallinity of the diamond layer deteriorates. x If there is an excess of carbon in the layer, it will hinder the formation of the carbon diffusion layer described below. This will cause the diamond layer and WC x The strength of the interface between the diamond layer and the diamond coating layer decreases, the diamond layer becomes more susceptible to peeling, and the tool life of the diamond-coated tool decreases.

[0038] WC x The x in the layer is measured by the following procedure: The diamond-coated tool is cut in the layer direction along the normal to the main surface of the diamond layer using a cross-section polisher (CP) (trademark) or a focused ion beam (FIB) to obtain a cross-sectional sample. x In the layer and WC x Three non-overlapping rectangular measurement fields of 40 nm x 40 nm are arbitrarily set within an area more than 30 nm away from the interface between the WC layer and the diamond layer. Each measurement field is analyzed using an energy dispersive X-ray analyzer (EDX) attached to a scanning electron microscope (SEM) or transmission electron microscope (TEM) to measure x. The average value of x in the three measurement fields is taken as the WC value. x Let x be the layer.

[0039] An example of a transmission electron microscope is a spherical aberration corrector, JEM-2100F (product name) manufactured by JEOL Ltd. An example of an EDX device is a silicon drift detector, JED-2200 (product name) manufactured by JEOL Ltd. It has been confirmed that, as long as measurements are performed on the same sample, there is almost no variation in the measurement results even if the measurement field of view is set arbitrarily.

[0040] <Arithmetic mean roughness Ra of the main surface on the diamond layer side> In the diamond-coated tool of embodiment 1, WC x The arithmetic mean roughness Ra of the diamond layer side principal surface of the layer may be 0.1 μm or more and 1.0 μm or less, 0.2 μm or more and 0.8 μm or less, 0.3 μm or more and 0.7 μm or less, or 0.4 μm or more and 0.6 μm or less.

[0041] The arithmetic mean roughness Ra is measured using the following procedure. Using a commercially available Vickers hardness tester, a square pyramidal indenter is pressed into the diamond layer, destroying and peeling it off. Plastic deformation of the indenter indentation area exposes an area where only the diamond layer, which has a higher Young's modulus than the WCx layer and is less susceptible to plastic deformation, has peeled off. The surface where only the diamond layer has peeled off and the WCx layer remains is then measured using a commercially available stylus surface roughness tester or a laser microscope, and calculations are made based on ISO 4287:1997 and ISO 25178-2:2012.

[0042] <WC x Layer thickness≫ In the diamond-coated tool of embodiment 1, WC x The thickness of the layer may be 0.05 μm or more and 5 μm or less, 0.2 μm or more and 3.4 μm or less, 0.3 μm or more and 3.4 μm or less, or 1.1 μm or more and 2.9 μm or less. x When the layer thickness is 0.05 μm or more, WC x The layer improves the cobalt diffusion suppression effect. x When the thickness of the layer is 5 μm or less, the stress in the WCx layer is reduced, and the adhesion of the WCx layer is improved. x The layer thickness may be 0.03 μm or more and 6.8 μm or less.

[0043] WC x The thickness of the layer is measured by the following procedure. A cross-sectional sample is obtained in the same manner as in the measurement of x above. In the cross-sectional sample, WC x The thickness of the layer is measured at three arbitrary points using a TEM. The average value of the thickness at the three points is used as the WC xThe thickness of the diamond layer, which will be described later, is also measured using the same procedure. It has been confirmed that, as long as measurements are taken on the same sample, there is almost no variation in the measurement results, even if the measurement location is arbitrarily set.

[0044] <Diamond layer> In the diamond-coated tool of embodiment 1, the diamond layer is x The diamond layer is placed directly on top of the WC x The diamond layer may be provided so as to cover the entire surface of the layer. x The diamond layer may be coated with at least a portion of the layer involved in cutting. x A portion of the layer may not be covered.

[0045] The diamond layer may contain unavoidable impurities to the extent that the effects of the present disclosure are not impaired. The content of the unavoidable impurities in the diamond layer may be 0% by mass or more and 0.2% by mass or less. Examples of the unavoidable impurities include boron, nitrogen, and oxygen.

[0046] <Raman spectrum> In the diamond-coated tool of embodiment 1, the Raman shift of the Raman spectrum of the diamond layer is 1200 cm -1 More than 1700cm -1 In the following range, the ratio Id / Is of the diamond peak area intensity Id to the area intensity Is of the entire spectrum should be 2×10 -3 5x10 or more -2 Less than 4.8×10 -3 Over 3.7 x 10 -2 Below, 5.6 x 10 -3 Over 3.5 x 10 -2 Below, 7.2 x 10 -3 Over 3.3 x 10 -2 or less, or 9.2 x 10 -3 Over 2.7 x 10 -2 The following is also acceptable.

[0047] The Id / Is ratio is measured using the following procedure: The surface of the diamond layer is mirror-polished using a diamond slurry with an average particle size of 3 μm. Three rectangular measurement fields of 50 μm x 50 μm are arbitrarily set on the surface of the diamond layer. Laser Raman measurement conforming to JIS-K0137 (2010) is performed in each measurement field to obtain a Raman spectrum. The measurement is performed at room temperature (20°C to 25°C) using a laser with a wavelength of 532 nm as excitation light. An example of a Raman spectrometer is the Lab RAM ARAMIS (trademark) manufactured by HORIBA.

[0048] The Raman spectrum was measured using image processing software (Ramanimager (trademark) manufactured by Nanophoton Corporation) at a Raman shift of 1200 cm -1 More than 1700cm -1 The ratio Id / Is of the diamond peak area intensity Id to the area intensity Is of the entire spectrum in the following range is calculated. The average value of Id / Is of the three measurement fields is taken as the above Id / Is. It has been confirmed that as long as the same sample is measured, there is almost no variation in the measurement results even if the measurement field is set arbitrarily.

[0049] <Diamond layer thickness> In the diamond-coated tool of embodiment 1, the thickness of the diamond layer may be 0.5 μm or more and 32 μm or less, 1 μm or more and 30 μm or less, 3 μm or more and 25 μm or less, or 5 μm or more and 20 μm or less. When the thickness of the diamond layer is 1 μm or more, the wear resistance is further improved. When the thickness of the diamond layer is 30 μm or less, the chipping resistance is further improved. The thickness of the diamond layer may be 0.5 μm or more and 32 μm or less.

[0050] <First area> As shown in FIG. 1, in the diamond-coated tool 10 of the first embodiment, WC x From the interface P between layer 2 and diamond layer 3, WC xThe cobalt content of the first region 4 sandwiched between the first imaginary plane S1, which is 30 nm away from the layer 2 side, and the second imaginary plane S2, which is 30 nm away from the interface P toward the diamond layer 3 side, may be 1.9 atomic % or less, or 0.1 atomic % to 1.9 atomic % or less, or 0.1 atomic % to 1.8 atomic % or less, or 0.1 atomic % to 1.5 atomic % or less, or 0.1 atomic % to 1.4 atomic % or less, or 0.5 atomic % to 1.3 atomic % or less, or 0.5 atomic % to 1.1 atomic % or less, or 0.5 atomic % to 1.0 atomic %.

[0051] When the cobalt content of the first region is 0.1 atomic % or more, WC x The stress near the interface between the WC layer and the diamond layer is relieved, x If the cobalt content of the first region exceeds 1.9 atomic %, the cobalt and diamond react easily during vapor phase synthesis of the diamond layer, and the diamond layer and the WC layer adhere well to each other. x The adhesion between the layers decreases.

[0052] The cobalt content of the first region is measured by the following procedure. (A1) A cross-sectional sample is obtained using the same method as the method for measuring x above. The cross-sectional sample is observed using an SEM or TEM to determine the WC x Three rectangular measurement fields of 60 nm × 60 nm were arbitrarily set around the interface between the WC layer and the diamond layer. As shown in Figure 3, one pair of opposite sides of the measurement field is parallel to the interface, and the other is perpendicular to the interface. x The distance to the layer side is 30 nm and the length is 60 nm. Side b is parallel to the interface, and the distance from the interface to the diamond layer side is 30 nm and the length is 60 nm. If the interface is curved, sides a and b should be parallel to any tangent to the interface.

[0053] (B1) In each measurement field, WC xThe composition is measured by line analysis using a TEM-attached EDX (TEM-EDX) or SEM-attached EDX (SEM-EDX) along a direction perpendicular to the interface from an arbitrary point on edge a on the layer side to an arbitrary point on edge b on the diamond layer side. The beam diameter for line analysis is 0.9 nm or less, the scan interval is 50 nm, and the acceleration voltage is 15 kV.

[0054] (C1) Based on the measurement results, the average value of the cobalt content in the measurement field of view is calculated. The average value of the cobalt content in the three measurement fields of view is set as the cobalt content in the first region. It has been confirmed that there is almost no variation in the measurement results, even if the measurement field of view is set arbitrarily, as long as the same sample is measured.

[0055] <Carbon diffusion layer> WC x The interface between the WC layer and the diamond layer x The first region sandwiched between the first imaginary plane at a distance of 30 nm from the interface to the diamond layer side and the second imaginary plane at a distance of 30 nm from the interface to the diamond layer side has a tungsten atom number N W Number of carbon atoms N C Ratio of N C / N W is 0.27 or more and 4.0 or less, and C / N W The average of the above formula 1 (Formula 1: WC x ) and the thickness of the carbon diffusion layer may be 5 nm or more and 30 nm or less. x At the interface between the diamond layer and the WC layer, the carbon constituting the diamond layer is x It is presumed that this is formed by diffusion into the layer side.

[0056] The thickness of the carbon diffusion layer may be 5 nm or more and 30 nm or less, 6.7 nm or more and 27.1 nm or less, 7.2 nm or more and 25 nm or less, 8.6 nm or more and 23.6 nm or less, 9.5 nm or more and 20 nm or less, 10 nm or more and 19.4 nm or less, 11.3 nm or more and 18.6 nm or less, or 13.4 nm or more and 17.2 nm or less. When the thickness of the carbon diffusion layer is 5 nm or more, the diamond layer and the WC x The diffusion of carbon atoms at the interface between the diamond layer and the WC layer is sufficient. x When the thickness of the carbon diffusion layer is 30 nm or less, the adhesion strength with the WC layer is further improved. x The layer is not overly carbonized, so WC x The occurrence of brittle fracture in the diamond layer and WC layer can be suppressed. x The adhesion between the layers is further improved.

[0057] The thickness of the carbon diffusion layer is measured by the following procedure. Line analysis is performed and the composition is measured using the same methods as (A1) and (B1) of the method for measuring the cobalt content of the first region. The line analysis results are plotted on a coordinate system in which the X axis is the distance from the measurement start point (any point on side a) and the Y axis is the content (atomic %) of carbon and tungsten based on the atomic number. In the first graph, the number of tungsten atoms, N W Number of carbon atoms N C Ratio of N C / N W Calculate the length d of the range A on the X axis where is between 0.27 and 4.0. Calculate the average value of the lengths d of the three measurement fields. N in range A C / N W Calculate the average of N in range A. C / N W The average of WC in Eq. x If the thickness d is larger than x in the above formula, the average value of the length d of the three measurement fields is taken as the thickness of the carbon diffusion layer.

[0058] Fig. 4 is an example of a first graph obtained with the diamond-coated tool of embodiment 1. In the first graph of Fig. 4, the X axis represents the distance from the measurement start point (any point on side a), and the Y axis represents the content (atomic %) of carbon and tungsten based on the number of atoms. In the first graph of Fig. 4, between distance P1 and distance P2, N C / N W is equal to or greater than 0.27 and equal to or less than 4.0. The length between the distance P1 and the distance P2 corresponds to the above-mentioned length d.

[0059] <Manufacturing method for diamond coated tools> A method for producing the diamond-coated tool of the first embodiment will be described. ≪Base material preparation process≫ Prepare a substrate. Details of the substrate are as described above.

[0060] <WC x Layer formation process≫ WC is deposited on the substrate by physical vapor deposition (PVD) x The conditions for using the arc ion plating method are as follows: The substrate is set in the arc ion plating device. A tungsten carbide target (a sintered or soluble target whose composition is WC and whose carbon content is 3 to 6.1 mass %) is set in the arc evaporation source of the arc ion plating device.

[0061] Next, the substrate temperature is set to 400-500°C and the gas pressure in the device is set to 1.0-3.5 Pa. Argon gas is introduced as the gas. Then, while the substrate (negative) bias voltage is maintained at 10-700 V and DC or pulse DC (frequency 10-300 kHz), an arc current of 80-150 A is supplied to the cathode electrode. Metal ions, etc. are generated from the arc evaporation source by supplying the arc current, and WC is deposited. x Form a layer.

[0062] WC x If the target thickness of the layer is T, then WC x After the layer thickness reaches 0.5T, an arc current of 151-200A is used.x The arithmetic mean roughness Ra of the layer can be adjusted to 0.1 μm or more and 1.0 μm or less.

[0063] WC x Before forming the layer, a step of treating the surface of the substrate may be carried out, for example, by using a hard ceramic medium such as alumina or SiC.

[0064] <Diamond layer formation process> WC x Diamond powder is applied to the layer and seeding treatment is performed. In the seeding treatment, diamond powder with an average particle size of 50 nm is applied to the WC layer on the substrate. x After rubbing onto the surface of the layer, the substrate is washed in ethanol and dried.Then, the substrate is set in a hot filament CVD film forming apparatus.

[0065] WC x The filament current is controlled so that the surface temperature of the layer is an average of 800°C. When the diamond layer thickness is 1 μm or less, methane and hydrogen are introduced so that the methane concentration is 0.1 to 2.0 volume %, and the diamond layer is formed. This promotes the formation of a carbon diffusion layer and improves the crystallinity of the diamond layer. The diamond layer is then formed while controlling the amount of methane and hydrogen introduced so that the methane concentration is 1.0 to 3.5 volume %, and a diamond-coated tool is obtained. The pressure during film formation is 500 mPa. [Example]

[0066] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0067] [Fabrication of diamond-coated tools] Diamond-coated tools of Samples 1 to 18 and Samples 1-1 and 1-2 were produced by the following steps.

[0068] ≪Base material preparation process≫ As a substrate, a cutting tip (model number: AOMT11T304PEFR-S) made of a tungsten carbide-based cemented carbide (W content: 90 mass %, C content: 9 mass %) was prepared.

[0069] <WC x Layer formation process≫ The substrate was set in an arc ion plating apparatus. A tungsten carbide target having the composition shown in Table 1 was set in the arc evaporation source of the arc ion plating apparatus. For example, "WC (3-4%)" in the composition column of Table 1 means tungsten carbide whose composition is WC and whose carbon content is 3 to 4 mass%.

[0070] Next, the gas pressure in the device was set to a value within the range of 1.0 to 3.5 Pa. Argon gas was introduced as the gas. Then, the substrate (negative) bias voltage was set to a value within the range of 10 to 700 V, and while maintaining it at DC, an arc current was supplied to the cathode electrode, and the substrate temperature was controlled as shown in Table 1. While controlling the WCx layer composition, WC x A layer was formed. x If the target thickness of the layer is T, then WC x The arc current was set to a value between 80 and 150 A until the layer thickness reached 0.5 T. The arc current thereafter was controlled as shown in the "Later Arc Current" column in Table 1, and an arbitrary WC x The roughness of the layer was controlled. x When the layer thickness reaches the thickness listed in Table 2, WC x The layer formation was completed.

[0071] <Diamond layer formation process> WC x Diamond powder was applied to the layer and seeding treatment was performed. In the seeding treatment, diamond powder with an average particle size of 50 nm was applied to the WC layer on the substrate. x After rubbing onto the surface of the layer, the substrate was washed in ethanol and dried.Then, the substrate was set in a hot filament CVD film forming apparatus.

[0072] WC xThe filament current was controlled so that the surface temperature of the layer reached an average of 800°C. For diamond layer thicknesses of 1 μm or less, methane and hydrogen were introduced so that the methane concentration reached the concentration listed in the "Gas Composition (Volume %), First Half" column of Table 1, and the diamond layer was then formed. The amount of methane and hydrogen introduced was then controlled so that the methane concentration reached the concentration listed in the "Gas Composition (Volume %), Second Half" column of Table 1. Diamond layer formation was terminated when the diamond layer thickness reached the thickness listed in Table 2. The pressure during deposition was 500 mPa. Each sample of diamond-coated tool was obtained through the above process.

[0073] [Table 1]

[0074] [Measurement of diamond coated tools] In each sample of diamond-coated tool, WC x Layer WC x x, WC x The arithmetic mean roughness Ra of the diamond layer-side main surface of the layer, the Id / Is of the diamond layer, the cobalt content of the first region, and the thickness of the carbon diffusion layer were measured by the method described in embodiment 1. The results are shown in Table 2. In all samples, the N of the carbon diffusion layer C / N W The average of WC x Layer composition WC x was larger than x in

[0075] [Table 2]

[0076] [Cutting test] Cutting tests were conducted using the diamond-coated tools of each sample. Each diamond-coated tool, shaped like AOMT11T304PEFR-S, was attached to an indexable cutter (Sumitomo Electric Industries, Ltd., WEZ11040E02) and used for cutting. The cutting conditions were as follows: workpiece: CFRP plate (150 x 300 x 6.3 mm), cutting speed Vc: 150 m / min, rotational feed f: 0.1 mm / rev, axial depth of cut: 7 mm, radial depth of cut: 1 mm.

[0077] [Consideration] The diamond-coated tools of Samples 1 to 16 correspond to Examples. The diamond-coated tools of Samples 1-1 and 1-2 correspond to Comparative Examples. It was confirmed that the diamond-coated tools of Samples 1 to 16 have longer tool lives than the diamond-coated tools of Samples 1-1 and 1-2.

[0078] Although the embodiments and examples of the present disclosure have been described above, it is originally intended that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the embodiments and examples described above, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0079] 1 base material, 2 WC x layer, 3 diamond layer, 4 first region, 10 diamond coated tool, 11 cutting edge ridge, P interface, S1 first second virtual surface second virtual surface.

Claims

1. a substrate made of a tungsten carbide-based cemented carbide; WC having a composition represented by the following formula 1 provided directly on the substrate ｘ Layers and Formula 1: WC ｘ In the formula 1, x is 0.27 or more and 0.67 or less, The WC ｘ a diamond layer disposed directly on the diamond-coated tool, a first region sandwiched between a first imaginary plane that is 30 nm away from the interface between the WC x layer and the diamond layer toward the WC x layer side, and a second imaginary plane that is 30 nm away from the interface toward the diamond layer side, includes a carbon diffusion layer in which the ratio N C / N W of the number of carbon atoms N C to the number of tungsten atoms N W is 0.27 or more and 4.0 or less; the average N C / N W of the carbon diffusion layer is greater than x in Equation 1; the carbon diffusion layer has a thickness of 5 nm or more and 30 nm or less; A diamond-coated tool, wherein the N C / N W is measured by performing line analysis on a cross section of the diamond layer of the diamond-coated tool along a normal to the main surface of the diamond layer using an energy dispersive X-ray spectrometer attached to a scanning transmission electron microscope.

2. The Raman shift of the Raman spectrum of the diamond layer is 1200 cm －１ More than 1700cm －１ In the following range, the ratio Id / Is of the diamond peak area intensity Id to the area intensity Is of the entire spectrum is 2 × 10 －３ 5x10 or more －２ 2. The diamond coated tool according to claim 1, wherein:

3. The WC ｘ The WC layer is then heated to a temperature of 1000° C. from the interface between the WC layer and the diamond layer. ｘ the cobalt content of the first region sandwiched between the first imaginary plane, which is at a distance of 30 nm toward the diamond layer side, and the second imaginary plane, which is at a distance of 30 nm from the interface toward the diamond layer side, is 1.9 atomic % or less; 3. A diamond-coated tool according to claim 1, wherein the cobalt content is measured by performing line analysis on a cross section of the diamond layer of the diamond-coated tool along the normal to the main surface of the diamond layer using the energy dispersive X-ray spectrometer attached to the scanning transmission electron microscope.

4. The WC ｘ 3. The diamond-coated tool according to claim 1, wherein the arithmetic mean roughness Ra of the main surface of the layer on the diamond layer side is 0.1 μm or more and 1.0 μm or less.

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