Diamond-coated tool

Abstract

This diamond-coated tool includes: a substrate made of tungsten carbide-based cemented carbide; a WC x layer provided directly above the substrate and having a composition represented by formula 1; and a diamond layer provided directly above the WC x layer, where x is 0.27 to 0.67 in formula 1: WC x .

Description

Diamond coated tools

[0001] This disclosure relates to diamond-coated tools.

[0002] Diamonds have extremely high hardness, and their smooth surfaces have an extremely low coefficient of friction. Since the establishment of the technology for forming diamond thin films by chemical vapor deposition (CVD) in the 1980s, diamond-coated tools have been developed by depositing a diamond layer on a three-dimensional substrate.

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

[0004] Japanese Patent 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 to suppress the diffusion of cobalt.

[0005] Japanese Patent Publication No. 2010-17791

[0006] The diamond-coated tool of this disclosure comprises a base material made of a tungsten carbide-based cemented carbide and a WC having the composition shown in the following formula 1, provided directly above the base material. ｘ Layers and Equation 1: WC ｘ In the above formula 1, x is 0.27 or more and 0.67 or less, and the above WC ｘ This is a diamond-coated tool comprising a diamond layer provided directly above a layer.

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

[0008] [Problems to be Solved by the Present Disclosure] When performing cutting using a cutting tool made of a diamond-coated cemented carbide of Patent Document 1, the diamond layer tends to peel off and the tool life is shortened. As a result of the inventor's intensive investigation into the cause of the peeling of the diamond layer, 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 directly 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 need for a diamond-coated tool that is less likely to cause diamond peeling during cutting and has a long tool life.

[0010] An object of the present disclosure is to provide a diamond-coated tool having a long tool life.

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

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

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

[0014] In the diamond-coated tool of the present disclosure, a WC layer is provided between the substrate and the diamond layer. When x of the WC layer is 0.27 or more, the amount of metallic tungsten that does not form a carbide among the tungsten in the WC layer is reduced. WC ｘ layer is provided. When x of the WC layer is 0.27 or more, the amount of metallic tungsten that does not form a carbide among the tungsten in the WC layer is reduced. ｘ layer is provided. When x of the WC layer is 0.27 or more, the amount of metallic tungsten that does not form a carbide among the tungsten in the WC layer is reduced. ｘ layer is provided. When x of the WC layer is 0.27 or more, the amount of metallic tungsten that does not form a carbide among the tungsten in the WC layer is reduced. ｘ ​​If there is a lot of metallic tungsten in the layer, WC ｘ The coefficient of thermal expansion of the layer increases. This causes the diamond layer and WC ｘ The interfacial strength with the layer decreases, making the diamond layer more prone to peeling, and reducing the tool life of the diamond-coated tool. In the diamond-coated tool of this disclosure, WC ｘ Because the amount of metallic tungsten in the layer is reduced, the diamond layer and WC ｘ The adhesion to the layer improves.

[0015] In the diamond-coated tools disclosed herein, WC ｘ By having a layer x of 0.67 or less, crystal mismatch with diamond is suppressed, the crystallinity of the diamond layer is good, and the diamond layer and WC ｘ The adhesion to the layer improves.

[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 Within the following range, the ratio Id / Is of the peak area intensity of diamond to the total area intensity Is of the spectrum is 2 × 10⁻⁶ －３ The above 5 x 10 －２ The following is also acceptable.

[0017] According to this, the crystallinity of the diamond layer is further improved, and the diamond layer and WC ｘ The adhesion to the 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 From the interface between the layer and the diamond layer, the WC ｘ The cobalt content of the first region sandwiched between a first virtual surface, which is 30 nm away from the layer, and a second virtual surface, which is 30 nm away from the interface towards the diamond layer, may be 1.9 atomic percent or less. The cobalt content is measured by performing 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.

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

[0020] (4) In any of (1) to (3) above, the WC ｘ From the interface between the layer and the diamond layer, the WC ｘ The first region sandwiched between a first virtual plane whose distance to the layer side is 30 nm and a second virtual plane whose distance from the interface to the diamond layer side is 30 nm is the number of atoms of tungsten N Ｗ The number of carbon atoms N Ｃ Ratio N Ｃ / N Ｗ However, it includes a carbon diffusion layer having a value of 0.27 or more and 4.0 or less, and the N of the carbon diffusion layer Ｃ / N Ｗ The average of is greater than x in the above formula 1, and the thickness of the carbon diffusion layer may be 5 nm or more and 30 nm or less. Ｃ / N Ｗ This is measured by performing 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 presence of a carbon diffusion layer with a thickness of 5 nm to 30 nm allows the diamond layer and WC to separate. ｘ The adhesion to the layer 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. If the arithmetic mean roughness Ra is 0.1 μm or more, the diamond layer and WC will be affected by the anchoring effect. ｘ The adhesion to the layer is further improved. If the arithmetic mean roughness Ra is 1.0 μm or less, WC ｘ During the initial stages of growing a diamond layer on top of another layer, the bonding between diamond grains after nucleation is accelerated, improving the adhesion of the diamond layer.

[0023] [Details of Embodiments of the Disclosure] Specific examples of the diamond-coated tools of the Disclosure will be described below with reference to the drawings. In the drawings of the Disclosure, the same reference numerals indicate the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth have been modified as appropriate for clarity and simplification of the drawings and do not necessarily represent actual dimensional relationships.

[0024] In this disclosure, the notation "A to B" means A or greater and B or less. If no unit is specified for A, and only a unit is specified for B, then the unit for A and the unit for B are the same.

[0025] In this disclosure, when compounds and the like are represented by chemical formulas, unless otherwise specified, the atomic ratios should include all conventionally known atomic ratios and should not necessarily be limited to those within the stoichiometric range.

[0026] If this disclosure includes one or more numerical values ​​as the lower and upper limits of a numerical range, any combination of any one numerical value listed as the lower limit and any one numerical value listed as the upper limit shall also be disclosed.

[0027] In this disclosure, “equipment,” “includes,” “possesses,” and variations thereof are open-ended terms. Open-ended terms may or may not include additional elements in addition to the essential elements. The statement “consists of” is a closed term. However, even a configuration expressed in closed terms may include additional elements that are usually incidental or irrelevant to the subject technology.

[0028] [Embodiment 1: Diamond-coated tool] As shown in Figure 1, a diamond-coated tool 10 of one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 1") comprises a base material 1 made of a tungsten carbide-based cemented carbide and a WC having the composition shown in the following formula 1 provided directly on the base material 1. ｘ Layer 2 and Equation 1: WC ｘ In equation 1, x is between 0.27 and 0.67, and WC ｘ It comprises a diamond layer 3 provided directly above layer 2.

[0029] The diamond-coated tool of Embodiment 1 may be, for example, a drill, an end mill, a replaceable cutting tip for drills, a replaceable cutting tip for end mills, a replaceable cutting tip for milling, a replaceable cutting tip for turning, a metal saw, a gear cutting tool, a reamer, a tap, etc. Figure 2 is a schematic diagram of an example of a diamond-coated tool. The diamond-coated tool 10 is a replaceable 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 can be used as the base material. The tungsten carbide-based cemented carbide may contain tungsten carbide particles and cobalt. The tungsten carbide particle content of the cemented carbide may be 77% by mass or more and 96% by mass or less. The cobalt content of the cemented carbide may be 3% by mass or more and 15% by mass or less. The total content of tungsten carbide particles and cobalt of the cemented carbide may be 80% by mass or more and 98% by mass or less. In addition to tungsten carbide and cobalt, the cemented carbide may contain other components. Other components include Ni, Fe, TiC, ZrC, HfC, VC, NbC, TaC, and Cr ３ C ２ Mo ２ It may also contain at least one selected from the group consisting of C, TiN, and ZrN. The content of other components of the cemented carbide 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 method for measuring the average particle size of tungsten carbide particles is as follows: In the cross-section of the cemented carbide, the equivalent circular diameter (Heywood diameter: equivalent circular diameter of the same area) of each tungsten carbide particle is measured, and the 50% cumulative particle size (equivalent circular 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 placed directly above the substrate. WC ｘ The layer may be provided so as to cover the entire substrate. ｘ The layer may cover at least the portion of the substrate that functions as a tool. In this disclosure, the portion that functions as a tool means the portion that comes into contact with the workpiece. For example, if the tool is a cutting tool, the portion that functions as a tool means the region within 0.5 μm of the cutting edge of the substrate. As long as the effects of this disclosure are not impaired, WC ｘ The layer does not need to cover a portion of the substrate.

[0034] ≪Composition≫ WC ｘ A layer refers to tungsten carbide where the atomic ratio of carbon (C) is x, with the atomic ratio of tungsten (W) being 1. WC ｘ The layer may contain unavoidable impurities, to the extent that they do not impair the effects of this disclosure. ｘ The content of unavoidable impurities in the layer may be between 0% by mass and 0.2% by mass. Examples of unavoidable impurities include boron, nitrogen, oxygen, iron, magnesium, and aluminum.

[0035] In the diamond-coated tool of Embodiment 1, 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 ｘThe amount of metallic tungsten in the layer increases. WC ｘ When the amount of metallic tungsten in the layer increases, WC ｘ The coefficient of thermal expansion of the layer increases. As a result, the diamond layer and WC ｘ The interface strength with the layer decreases, making the diamond layer more prone to peeling, and thus reducing the tool life of the diamond-coated tool.

[0037] If the above x exceeds 0.67, WC ｘ The layer becomes close to the WC composition of a typical cemented carbide, causing crystal mismatch with the diamond and degrading the crystallinity of the diamond layer. ｘ If there is an excess of carbon in the layer, the formation of the carbon diffusion layer, described below, is inhibited. This results in the diamond layer and WC ｘ The interface strength with the layer decreases, making the diamond layer more prone to peeling, and thus reducing the tool life of the diamond-coated tool.

[0038] WC ｘ The x-coating in the layer is measured by the following procedure: A diamond-coated tool is cut in the layer direction 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. In the cross-sectional sample, WC ｘ It is in the layer and also WC ｘ Three arbitrary 40 nm x 40 nm rectangular measurement fields are set within a region more than 30 nm away from the interface between the layer and the diamond layer, and they do not overlap. In each measurement field, analysis is performed using an energy-dispersive X-ray spectrometer (EDX) attached to a scanning electron microscope (SEM) or transmission electron microscope (TEM), and x is measured. The average value of x from the three measurement fields is taken as WC. ｘ Let x be the number in the layer.

[0039] Examples of transmission electron microscopes include the JEM-2100F (product name), a spherical aberration corrector manufactured by JEOL Ltd. Examples of EDX devices include the JED-2200 (product name), a silicon drift detector manufactured by JEOL Ltd. It has been confirmed that, as long as the same sample is used, there is almost no variation in the measurement results even when the measurement field of view is arbitrarily set.

[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 main surface on the diamond layer side 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 by the following procedure: Using a commercially available Vickers hardness tester, an arbitrary square pyramidal indenter is pressed in to break and peel off the diamond layer. At this time, the area around the indenter indentation is exposed where only the diamond layer, which has a higher Young's modulus and is less prone to plastic deformation than the WCx layer, has peeled off due to the plastic deformation of the indenter indentation area. The surface on which only the diamond layer has peeled off and the WCx layer remains is then used with a commercially available stylus-type surface roughness tester or laser microscope to calculate the roughness according to ISO 4287:1997 and ISO 25178-2:2012.

[0042] ≪WC ｘ Layer thickness≫ In the diamond coated tool of Embodiment 1, WC ｘ The layer thickness 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. WC ｘ If the layer thickness is 0.05 μm or more, WC ｘ The diffusion suppression effect of the layer by cobalt is improved. WC ｘ When the layer thickness is 5 μm or less, the stress in the WCx layer decreases, and the adhesion strength of the WCx layer improves. ｘ The layer thickness may be between 0.03 μm and 6.8 μm.

[0043] WC ｘ The thickness of the layer is measured by the following procedure. A cross-sectional sample is obtained using the same method as the measurement method for x described above. In the cross-sectional sample, WC ｘ The thickness of the layer is measured at three arbitrary points using a TEM. The average of the three thicknesses is measured in WC. ｘThis is defined as the thickness of the layer. The thickness of the diamond layer, described later, is measured using the same procedure. It has been confirmed that, as long as the same sample is used, 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 WC ｘ It is placed directly above the layer. The diamond layer is WC ｘ The layer may be provided so as to cover the entire surface of the layer. The diamond layer is WC ｘ The diamond layer may cover at least the portion of the layer involved in cutting. Unless impairing the effects of this disclosure, the diamond layer may be WC ｘ It is not necessary for the layer to be partially covered.

[0045] The diamond layer may contain unavoidable impurities to the extent that they do not impair the effects of this disclosure. The content of unavoidable impurities in the diamond layer may be 0% by mass or more and 0.2% by mass or less. Examples of 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 cm². －１ More than 1700cm －１ Within the following range, the ratio Id / Is of the peak area intensity of diamond to the total area intensity Is of the spectrum is 2 × 10⁻⁶, from the viewpoint of improving the crystallinity of the diamond layer. －３ The above 5 x 10 －２ The following is also acceptable: 4.8 x 10 －３ The above 3.7 x 10 －２ Below, 5.6 x 10 －３ The above 3.5 x 10 －２ Below, 7.2 x 10 －３ The above 3.3 x 10 －２ The following, or 9.2 x 10 －３ The above 2.7 x 10 －２ The following is also acceptable.

[0047] The above Id / Is is measured by the following procedure. The surface of the diamond layer is mirror-polished using a diamond slurry with an average particle size of 3 μm. Arbitrarily set three rectangular measurement fields of 50 μm × 50 μm on the surface of the diamond layer. In each measurement field, laser Raman measurement is performed in accordance with JIS-K0137 (2010) to obtain a Raman spectrum. The measurement is performed at room temperature (20°C or higher and 25°C or lower) using a laser with a wavelength of 532 nm as the excitation light. Examples of the Raman spectrometer include Lab RAM ARAMIS (trademark) manufactured by HORIBA.

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

[0049] ≪Thickness of diamond layer≫ 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 defect resistance is further improved. The thickness of the diamond layer may be 0.5 μm or more and 32 μm or less.

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

[0051] When the cobalt content of the first region is 0.1 atomic % or more, the stress near the interface between the WC ｘ layer and the diamond layer is relaxed, and the adhesion between the WC ｘ layer and the diamond layer is good. When the cobalt content of the first region exceeds 1.9 atomic %, cobalt and diamond are likely to react during the vapor-phase synthesis of the diamond layer, and the adhesion between the diamond layer and the WC ｘ layer decreases.

[0052] The cobalt content of the first region is measured by the following procedure. (A1) A cross-sectional sample is obtained by the same method as the above-described method for measuring x. The cross-sectional sample is observed with SEM or TEM, and three arbitrary measurement fields of a 60 nm × 60 nm rectangle are set centered on the interface between the WC ｘ layer and the diamond layer. As shown in FIG. 3, of a set of opposite sides of the measurement field, side a is parallel to the interface and has a distance of 30 nm from the interface to the WC ｘ layer side and a length of 60 nm. Side b is parallel to the interface and has a distance of 30 nm from the interface to the diamond layer side and a length of 60 nm. When the interface is a curve, side a and side b only need to be parallel to an arbitrary tangent of the interface.

[0053] (B1) In each measurement field, WC ｘLine analysis is performed using a TEM-equipped EDX (TEM-EDX) or a SEM-equipped EDX (SEM-EDX) from an arbitrary point on edge a of the layer to an arbitrary point on edge b of the diamond layer, and along a direction perpendicular to the interface, to measure the composition. 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 is calculated. The average value of the cobalt content in the three measurement fields is taken as the cobalt content of the first region. It has been confirmed that there is almost no variation in the measurement results even if the measurement field is set arbitrarily, as long as the same sample is measured.

[0055] <Carbon Diffusion Layer> WC ｘ From the interface between the layer and the diamond layer, WC ｘ The first region, sandwiched between a first virtual plane with a distance of 30 nm towards the layer and a second virtual plane with a distance of 30 nm from the interface towards the diamond layer, has a tungsten atom count of N. Ｗ The number of carbon atoms N Ｃ Ratio N Ｃ / N Ｗ However, it includes a carbon diffusion layer having a value of 0.27 or more and 4.0 or less, and the N of the carbon diffusion layer Ｃ / N Ｗ The average is given by the above formula 1 (Formula 1: WC ｘ The carbon diffusion layer is greater than x in ), and the thickness of the carbon diffusion layer may be between 5 nm and 30 nm. The carbon diffusion layer is WC ｘ In the interface region between the layer and the diamond layer, the carbon constituting the diamond layer is WC ｘ It is presumed that it is formed by diffusion toward the layer.

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

[0057] The thickness of the carbon diffusion layer is measured by the following procedure. Line analysis is performed using the same method as (A1) and (B1) for measuring the cobalt content of the first region described above, and the composition is measured. The line analysis results are shown in a first graph in a coordinate system where 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 number of atoms. In the first graph, the number of atoms of tungsten N Ｗ The number of carbon atoms N Ｃ Ratio N Ｃ / N Ｗ However, the length d of the X-axis range A, where the value is between 0.27 and 4.0, is determined. The average value of the lengths d of the three measurement fields is calculated. N in range A Ｃ / N Ｗ Calculate the average of N in range A. Ｃ / N Ｗ The average of Equation 1 is WC ｘ If x is greater than the value at the three measurement fields, the average of the lengths d of the three measurement fields is taken as the thickness of the carbon diffusion layer.

[0058] Figure 4 is an example of a first graph obtained with the diamond-coated tool of Embodiment 1. In the first graph of Figure 4, the X axis is the distance from the measurement start point (any point on side a), and the Y axis is the atomic-based content (atomic %) of carbon and tungsten. In the first graph of Figure 4, between distance P1 and distance P2, N Ｃ / N Ｗ However, it is between 0.27 and 4.0. The length between distance P1 and distance P2 corresponds to the above length d.

[0059] <Method for Manufacturing Diamond-Coated Tools> The method for manufacturing the diamond-coated tool of Embodiment 1 will now be described. <Substrate Preparation Process> Prepare the substrate. Details of the substrate are as described above.

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

[0061] Next, the substrate temperature is set to 400-500°C and the gas pressure inside the apparatus is set to 1.0-3.5 Pa. Argon gas is introduced as the gas. Then, while maintaining the substrate (negative) bias voltage at 10-700V and DC or pulsed DC (frequency 10-300kHz), an arc current of 80-150A is supplied to the cathode electrode. By supplying the arc current, metal ions etc. are generated from the arc-type evaporation source, thereby WC ｘ It forms layers.

[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. This results in WC ｘ The arithmetic mean roughness Ra of the layer can be adjusted to between 0.1 μm and 1.0 μm.

[0063] WC ｘ A process of treating the substrate surface may be performed before forming the layer. Examples of surface treatment processes include surface treatment using hard ceramic media such as alumina or SiC.

[0064] ≪Diamond Layer Formation Process≫ WC ｘ Diamond powder is applied to the layer and then seeded. In the seeding process, diamond powder with an average particle size of 50 nm is applied to the substrate. ｘAfter rubbing it onto the layer surface, it is washed in ethanol and dried. Next, the substrate is set in a thermal filament CVD deposition apparatus.

[0065] WC ｘ The filament current is controlled so that the surface temperature of the layer averages 800°C. In the range where the thickness of the diamond layer is 1 μm or less, methane and hydrogen are introduced to form the diamond layer so that the methane concentration is 0.1 to 2.0 volume percent. This promotes the formation of the carbon diffusion layer and improves the crystallinity of the diamond layer. Subsequently, the amount of methane and hydrogen introduced is controlled to form the diamond layer while maintaining a methane concentration of 1.0 to 3.5 volume percent, thereby obtaining a diamond-coated tool. The pressure during film formation is 500 mPa.

[0066] This embodiment will be described in more detail by reference to examples. However, this embodiment is not limited by these examples.

[0067] [Preparation of diamond-coated tools] Diamond-coated tools for samples 1 to 18 and samples 1-1 to 1-2 were prepared using the following process.

[0068] <<Substrate Preparation Process>> As the substrate, a cutting tip made of tungsten carbide-based cemented carbide (W content 90% by mass, C content 9% by mass) (model number: AOMT11T304PEFR-S) was prepared.

[0069] ≪WC ｘ Layer Formation Process: The substrate was set in the arc ion plating apparatus. A tungsten carbide target having the composition described in Table 1 was set in the arc evaporation source of the arc ion plating apparatus. For example, "W-C (3-4%)" in the composition column of Table 1 refers to tungsten carbide with a composition of WC and a carbon content of 3-4% by mass.

[0070] Next, the gas pressure inside the apparatus was set to an arbitrary 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 an arbitrary value within the range of 10 to 700 V, and while maintaining it in DC, an arc current was supplied to the cathode electrode, the substrate temperature was controlled as shown in Table 1, and the WCx layer composition was controlled while WC ｘ A layer was formed. WC ｘ If the target thickness of the layer is T, then WC ｘ The arc current was set to any value within the range of 80 to 150 A until the layer thickness reached 0.5 T. Thereafter, the arc current was controlled as shown in the "Second Half of Arc Current" column of Table 1, and any WC was used. ｘ The layer coarseness was controlled. WC ｘ When the layer thickness reaches the thickness listed in Table 2, WC ｘ Layer formation is complete.

[0071] ≪Diamond Layer Formation Process≫ WC ｘ Diamond powder was applied to the layer and then seeded. In the seeding process, diamond powder with an average particle size of 50 nm was applied to the WC on the substrate. ｘ After rubbing it onto the layer surface, it was washed in ethanol and dried. Next, the substrate was set in a thermal filament CVD deposition apparatus.

[0072] WC ｘ The filament current was controlled so that the surface temperature of the layer averaged 800°C. In the range where the thickness of the diamond layer was 1 μm or less, methane and hydrogen were introduced so that the methane concentration was as indicated in the "Gas Composition (Volume %) First Half" column of Table 1, and the diamond layer was formed. Subsequently, the amount of methane and hydrogen introduced was controlled so that the methane concentration was as indicated in the "Gas Composition (Volume %) Second Half" column of Table 1, and the diamond layer was formed. When the thickness of the diamond layer reached the thickness indicated in Table 2, the formation of the diamond layer was terminated. The pressure during film formation was 500 mPa. Diamond-coated tools for each sample were obtained by the above process.

[0073]

[0074] [Measurement of diamond-coated tools] For each diamond-coated tool of the sample, WC ｘ Layer WC ｘ x, WC ｘ The arithmetic mean roughness Ra of the main surface on the diamond layer side 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 using 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 is WC ｘ Layer composition WC ｘ It was greater than x in [the given location].

[0075]

[0076] [Cutting Test] Cutting tests were performed using diamond-coated tools for each sample. Diamond-coated tools for each sample with the shape of AOMT11T304PEFR-S were attached to an indexable tip cutter (Sumitomo Electric WEZ11040E02) and cutting was performed. 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] [Discussion] The diamond-coated tools of Samples 1 to 16 correspond to the examples. The diamond-coated tools of Samples 1-1 to 1-2 correspond to the comparative examples. It was confirmed that the diamond-coated tools of Samples 1 to 16 have a longer tool life than the diamond-coated tools of Samples 1-1 to 1-2.

[0078] While embodiments and examples of this disclosure have been described above, it is intended from the outset that the configurations of each of the embodiments and examples described above may be combined or modified in various ways as appropriate. The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments and examples described above, and all modifications within the scope of the claims are intended to be included in the meaning of equivalences.

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

Claims

1. A base material made of a tungsten carbide-based cemented carbide, and a WC having the composition shown in the following formula 1, provided directly above the base material. ｘ Layers and Equation 1: WC ｘ In the above formula 1, x is 0.27 or more and 0.67 or less, and the above WC ｘ A diamond-coated tool comprising a diamond layer provided directly above a layer.

2. The Raman shift of the Raman spectrum of the diamond layer is 1200 cm². －１ More than 1700cm －１ Within the following range, the ratio Id / Is of the peak area intensity of diamond to the total area intensity Is of the spectrum is 2 × 10⁻⁶ －３ The above 5 x 10 －２ The diamond-coated tool according to claim 1, which is as follows:

3. The WC ｘ From the interface between the layer and the diamond layer, a first virtual plane at a distance of 30 nm from the WC ｘ layer side and a second virtual plane at a distance of 30 nm from the interface to the diamond layer side, the cobalt content in the first region sandwiched therebetween is 1.9 atomic% or less, and the cobalt content is measured by performing line analysis using an energy dispersive X-ray spectrometer attached to a scanning transmission electron microscope on a cross section along the normal of the main surface of the diamond layer of the diamond-coated tool. The diamond-coated tool according to claim 1 or claim 2.

4. The aforementioned WC ｘ From the interface between the layer and the diamond layer, the WC ｘ The first region sandwiched between a first virtual plane whose distance to the layer side is 30 nm and a second virtual plane whose distance from the interface to the diamond layer side is 30 nm is the number of atoms of tungsten N Ｗ The number of carbon atoms N Ｃ Ratio N Ｃ / N Ｗ However, it includes a carbon diffusion layer having a value of 0.27 or more and 4.0 or less, and the N of the carbon diffusion layer Ｃ / N Ｗ The average of is greater than x in formula 1, the thickness of the carbon diffusion layer is 5 nm or more and 30 nm or less, and the N Ｃ / N Ｗ The diamond-coated tool according to any one of claims 1 to 3, wherein the measurement is made by performing 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.

5. The aforementioned WC ｘ The diamond coating tool according to any one of claims 1 to 4, wherein the arithmetic mean roughness Ra of the main surface on the diamond layer side of the layer is 0.1 μm or more and 1.0 μm or less.

Images