Diamond-coated tools and methods of making the same

Abstract

A diamond-coated tool has a substrate and a diamond layer disposed on the substrate, the diamond layer having a skewness Ssk defined by ISO 25178 greater than 0.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a diamond-coated tool and a manufacturing method thereof. BACKGROUND

[0002] Diamond has a very high hardness, and a smooth surface thereof has an extremely low coefficient of friction. Thus, natural single-crystal diamond and artificial diamond powder have been applied to tool uses. Further, after a technology for forming a diamond thin film based on a chemical vapor deposition (CVD) method was established in the 1980s, a cutting tool and a wear-resistant tool (hereinafter, these tools are also referred to as "diamond-coated tool") on which diamond is deposited on a three-dimensional substrate were developed.

[0003] In Japanese Patent Application Publication No. 2001-501873 (Patent Literature 1), a diamond-coated body in which a surface of a substrate composed of cemented carbide or cermet is coated with a diamond layer is disclosed.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2001-501873 SUMMARY

[0007] The diamond-coated tool of the present disclosure includes a substrate and a diamond layer disposed on the substrate,

[0008] The skewness Ssk of the diamond layer defined by ISO 25178 is greater than 0.

[0009] The manufacturing method of the diamond-coated tool of the present disclosure is the manufacturing method of the diamond-coated tool described above, in which

[0010] The manufacturing method of the diamond-coated tool includes:

[0011] a step of preparing a substrate;

[0012] a step of forming a diamond layer on the substrate by a chemical vapor deposition method; and

[0013] a step of performing oxygen ion etching on the diamond layer to obtain a diamond-coated tool. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a drawing for explaining a representative structural example of the diamond-coated tool according to Embodiment 1.

[0015] Figure 2 is a drawing for explaining a case where the skewness Ssk is greater than 0.

[0016] Figure 3 is a graph for explaining a case where skewness Ssk is less than 0.

[0017] Figure 4 is a graph showing one example of a Raman spectrum of the diamond coated tool according to Embodiment 1. DETAILED DESCRIPTION

[0018] [Problem to be Solved by the Invention]

[0019] In recent years, from the viewpoint of improving productivity, especially in cutting processing of aluminum alloy, a diamond coated tool having excellent resistance to fusion and wear, and having a longer tool life is required.

[0020] [Effects of the Invention]

[0021] The diamond coated tool of the present disclosure can also have a longer tool life especially in cutting processing of aluminum alloy.

[0022] [Explanation of Embodiments of the Invention]

[0023] First, an embodiment of the present disclosure is explained.

[0024] (1) The diamond coated tool of the present disclosure has a substrate and a diamond layer disposed on the substrate,

[0025] The skewness Ssk of the diamond layer prescribed by ISO 25178 is greater than 0.

[0026] The diamond coated tool of the present disclosure can also have a longer tool life especially in cutting processing of aluminum alloy.

[0027] (2) Preferably, the surface roughness Ra of the diamond layer prescribed by JIS B 0601:2013 is 0.5 μm or less.

[0028] By this, the resistance to fusion of the diamond coated tool is improved, and the tool life is further lengthened. In addition, the surface quality of the workpiece is also improved.

[0029] (3) Preferably, in a case where the Raman shift of the diamond layer is measured to be 900 cm -1 and 2000 cm -1 or more, the ratio Id / Is of the peak area intensity Id of the diamond to the area intensity Is of the entire spectrum is 0.08 or more.

[0030] By this, sp3carbon in the diamond layer is more, and sp2carbon which easily fuses to aluminum alloy is less, so the resistance to fusion of the diamond coated tool is improved, and the tool life is further lengthened.

[0031] (4) Preferably, the oxygen content in the diamond layer is 20 atomic % or more at a maximum in a region R surrounded by a main face S of a surface side of the diamond-coated tool and a virtual face Q at a distance of 20 nm from the main face S in a normal direction of the main face S toward the substrate side.

[0032] Thus, the oxidation resistance of the diamond layer is improved, the fusion bonding resistance and the wear resistance of the diamond-coated tool are improved, and the tool life is further lengthened.

[0033] (5) The manufacturing method of the diamond-coated tool of the present disclosure is the manufacturing method of the diamond-coated tool described above, wherein

[0034] The manufacturing method of the diamond-coated tool comprises:

[0035] a step of preparing a substrate;

[0036] a step of forming a diamond layer on the substrate by a chemical vapor deposition method; and

[0037] a step of obtaining a diamond-coated tool by performing oxygen ion etching on the diamond layer.

[0038] Thus, in cutting processing of an aluminum alloy, in particular, a diamond-coated tool capable of having a long tool life can be obtained.

[0039] [Details of Embodiments of the Present Disclosure]

[0040] Hereinafter, specific examples of the diamond-coated tool and the manufacturing method thereof of the present disclosure will be described with reference to the drawings. In the drawings of the present disclosure, the same reference numerals denote the same parts or corresponding parts. In addition, the dimensional relationships of length, width, thickness, depth, and the like are appropriately changed for the clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0041] In the present specification, the expression in the form of "A to B" means the upper limit and the lower limit of the range (i.e., A or more and B or less), and when the unit is not described in A but only described in B, the unit of A is the same as the unit of B.

[0042] <Embodiment 1: Diamond-Coated Tool>

[0043] Use Figure 1 The diamond-coated tool according to Embodiment 1 will be described. As shown in FIG. 1, the diamond-coated tool 10 comprises a substrate 1 and a diamond layer 2 disposed on the substrate 1, and the skewness Ssk of the diamond layer 2 defined by ISO 25178 is greater than 0. Figure 1

[0044] ​The diamond-coated tool of the present disclosure can also have a long tool life, particularly in cutting processing of aluminum alloys. The reason is not clear, but is presumed as follows.

[0045] First, in order to easily understand the present disclosure, the following Figure 2 and Figure 3 Skewness (kurtosis) prescribed by ISO 25178 (hereinafter, also referred to as "Ssk") is explained. Figure 2 is a diagram for explaining a case where the skewness of a surface is greater than 0. Figure 3 is a diagram for explaining a case where the skewness of a surface is less than 0. Figure 2 and Figure 3 are cross-sectional views along the direction of the normal line of a surface, respectively.

[0046] Skewness Ssk is one of three-dimensional surface property parameters prescribed in ISO 25178, and indicates the deviation of the height distribution from the mean plane. As Figure 2 indicates, Ssk is greater than 0 (positive) in a case where the concave-convex of a surface is biased to the lower side with respect to the mean plane L1. As Figure 3 indicates, Ssk is less than 0 (negative) in a case where the concave-convex of a surface is biased to the upper side with respect to the mean plane L2. In a case where the concave-convex of a surface is equal with respect to the mean plane (not illustrated), Ssk is 0 (zero).

[0047] In the diamond-coated tool of the present disclosure, the skewness (Ssk) of the diamond layer 2 is greater than 0, and the concave-convex of the surface of the diamond layer is biased to the lower side as Figure 2 indicates. Thereby, in a case where cutting oil is used at the time of cutting processing, the cutting oil is easily held in the concave portion of the surface. Therefore, the diamond-coated tool is also less likely to generate welding, particularly at the time of cutting of aluminum alloys, can suppress the nose wear caused by welding, and can have a long tool life.

[0048] The diamond-coated tool can further include any other structure on the basis of the substrate and the diamond layer. The diamond layer preferably coats the entire surface of the substrate, and preferably coats at least the nose portion of the substrate. Furthermore, even if a part of the substrate is not coated with the diamond layer, it does not depart from the scope of the present embodiment.

[0049] <Substrate>

[0050] As the base material of the diamond-coated tool of the present disclosure, a base material containing publicly known hard particles can be used. For example, as examples of such base materials, cemented carbide (for example, WC-based cemented carbide, and also including cemented carbide containing Co or further containing Ti, Ta, Nb, or the like on the basis of WC), cermet (with TiC, TiN, TiCN, or the like as a main component), high-speed steel, tool steel, ceramic (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, alumina, and a mixture thereof, or the like), cubic boron nitride sintered body, diamond sintered body, and the like can be listed.

[0051] <diamond layer>

[0052] (skewness Ssk)

[0053] The skewness Ssk of the diamond layer of the present disclosure is greater than 0 as prescribed by ISO 25178. Thereby, when cutting oil is used at the time of cutting processing, the cutting oil is easily held in the recesses of the surface. Therefore, the diamond-coated tool is not easily subjected to welding, especially at the time of cutting of an aluminum alloy, and the tool life can be extended by suppressing the tool nose wear caused by welding.

[0054] The lower limit of the Ssk of the diamond layer is greater than 0, and is preferably 0.05 or greater, 0.1 or greater. The upper limit of the Ssk of the diamond layer is preferably 1.0 or less, 0.8 or less, 0.6 or less. The Ssk of the diamond layer is preferably greater than 0 and 1.0 or less, 0.05 or greater and 0.8 or less, 0.1 or greater and 0.6 or less.

[0055] Regarding the Ssk of the diamond layer, the surface of the diamond layer is measured in accordance with ISO 25178-2:2012 and ISO 25178-3:2012 using a laser microscope ("OPTELICS HYBRID" (trademark) manufactured by Lasertech Corporation).

[0056] Regarding the measurement field of the Ssk of the diamond layer, five fields of 200 μm square are arbitrarily set within a range of 1 mm or less from the ridge line of the tool nose. The Ssk is measured for each of the five measurement fields. The average value of the Ssk in the five measurement fields is taken as the Ssk of the diamond layer.

[0057] (surface roughness Ra)

[0058] The surface roughness Ra of the diamond layer of the present disclosure is preferably 0.5 μm or less as prescribed by JIS B 0601:2013. Thereby, the welding resistance of the diamond-coated tool is improved, and the tool life is further extended. In addition, the surface quality of the workpiece to be cut is also improved.

[0059] The upper limit of the surface roughness Ra of the diamond layer is preferably 0.5 μm or less, 0.45 μm or less, 0.4 μm or less. The lower limit of the surface roughness Ra of the diamond layer is preferably 0.01 μm or more, 0.05 μm or more, 0.1 μm or more. The surface roughness Ra of the diamond layer is preferably 0.01 μm or more and 0.5 μm or less, 0.05 μm or more and 0.45 μm or less, 0.1 μm or more and 0.4 μm or less.

[0060] The surface roughness Ra of the diamond layer refers to the arithmetic average roughness Ra defined in JIS B 0601:2013. The surface roughness Ra of the diamond layer is measured in accordance with JIS B 0601:2013 using a laser microscope ("OPTELICS HYBRID" (trademark) manufactured by Lasertech Corporation) on the surface of the diamond layer.

[0061] The measurement field of the surface roughness Ra of the diamond layer is arbitrarily set to five fields of 200 μm square within a range of 1 mm or less from the edge line of the tool tip. The surface roughness Ra is measured for each of the five measurement fields. The average of the surface roughness Ra in the five measurement fields is taken as the surface roughness Ra of the diamond layer.

[0062] (Raman spectrum)

[0063] In a case where the Raman shift of the diamond layer of the present disclosure is measured to be 900 cm -1 or more and 2000 cm -1 or less, the ratio Id / Is of the peak area intensity Id of the diamond to the area intensity Is of the entire spectrum is preferably 0.08 or more.

[0064] The larger the above ratio Id / Is, the more sp3 carbon in the diamond layer and the less sp2 carbon that is easily brazed to the aluminum alloy. In the diamond layer of the present disclosure, since the ratio Id / Is is 0.08 or more, the amount of sp2 carbon in the diamond layer is reduced, the brazing resistance of the diamond-coated tool is improved, and the tool life is further lengthened.

[0065] The lower limit of the ratio Id / Is is preferably 0.08 or more, 0.085 or more, 0.09 or more. The upper limit of the ratio Id / Is is preferably 0.5 or less, 0.4 or less, 0.3 or less. The ratio Id / Is is preferably 0.08 or more and 0.5 or less, 0.085 or more and 0.4 or less, 0.09 or more and 0.3 or less.

[0066] In the present specification, the above ratio Id / Is is calculated by the following steps (1-1) to (1-4).

[0067] (1-1) A rectangular measurement field of 200 μm x 200 μm (hereinafter, also referred to as "Raman spectroscopy measurement field") was set on the diamond layer surface of the tool surface. Five Raman spectroscopy measurement fields were set.

[0068] (1-2) For each Raman spectroscopy measurement field, a Raman spectrum in the range of 900 cm -1 to 2000 cm -1 was obtained by laser Raman measurement according to JIS K 0137 (2010). At this time, the wavelength of the light used as the incident light was ultraviolet (325 nm). The Raman spectroscopy device used was "Raman touch" (trademark) manufactured by Nanophoton Co., Ltd. One example of the Raman spectrum of the diamond layer of the present disclosure is shown in Figure 4 . In Figure 4 , the spectrum represented by Sd represents the spectrum originating from the diamond, and the spectrum represented by Ss represents Figure 4 the total of all the spectra shown in .

[0069] (1-3) For the above Raman spectrum, the ratio Id / Is of the peak area intensity Id of the diamond to the area intensity Is of the entire spectrum was calculated using image processing software ("Raman imager" (trademark) manufactured by Nanophoton Co., Ltd.).

[0070] (1-4) The average value of the ratio Id / Is in the five measurement fields was calculated, and this average value was taken as the ratio Id / Is of the diamond layer.

[0071] (Oxygen content ratio)

[0072] Preferably, the diamond layer of Embodiment 1 has a maximum value of the oxygen content ratio of 20 atomic % or more in the region R surrounded by the main surface S of the surface side of the diamond-coated tool and the virtual surface Q at a distance of 20 nm from the main surface S in the normal direction of the main surface S toward the substrate side.

[0073] Thus, the oxidation resistance of the diamond layer is improved, and the fusion bonding resistance and the wear resistance of the diamond-coated tool are improved, and the tool life is further lengthened.

[0074] The lower limit of the maximum value of the oxygen content ratio in the region R of the diamond layer is preferably 20 atomic % or more, 25 atomic % or more, or 30 atomic % or more. The upper limit of the maximum value of the oxygen content ratio is preferably 90 atomic % or less, 85 atomic % or less, or 80 atomic % or less. The maximum value of the oxygen content ratio is preferably 20 atomic % or more and 90 atomic % or less, 25 atomic % or more and 85 atomic % or less, or 30 atomic % or more and 80 atomic % or less.

[0075] In the present specification, the oxygen content in the region R of the diamond layer is measured using an Auger electron spectrometer ("PHI 4800" (trademark) manufactured by ULVAC-PHI, Inc.) in accordance with JIS K 0146:2002 (ISO 14606:2000) while etching the surface of the diamond layer.

[0076] The measurement conditions are as follows.

[0077] (Electron beam parameters)

[0078] Electron energy: 10 kV, current value: 3 nA, incident angle: 15°

[0079] (Ion beam (sputtering parameters))

[0080] Ion species: argon, acceleration voltage: 1 kV, current value: 7 mA, grating area 1.5 mm, time: 2 minutes

[0081] (Measurement of signals)

[0082] Differential mode

[0083] (Other)

[0084] The measured elements are all of carbon, oxygen, and other detected elements. The oxygen atomic concentration is calculated with respect to all of the analyzed elements.

[0085] The etching is performed in a direction from the surface side toward the substrate side along the normal direction of the surface of the diamond layer (hereinafter also referred to as "depth direction"). The measurement of the oxygen content is performed at points at intervals of 2 nm in the depth direction of the diamond layer to a point at a depth of 20 nm or more. Thus, the oxygen content at intervals of 2 nm can be measured up to a point at a depth of 20 nm or more in the depth direction of the diamond layer.

[0086] (Thickness)

[0087] The lower limit of the thickness of the diamond layer of the present disclosure can be set to 1 μm or more, 2 μm or more, or 3 μm or more. The upper limit of the thickness of the diamond layer of the present disclosure can be set to 40 μm or less, 35 μm or less, or 30 μm or less. The thickness of the diamond layer of the present disclosure can be set to 1 μm or more and 40 μm or less, 2 μm or more and 35 μm or less, or 3 μm or more and 30 μm or less.

[0088] In the present specification, the thickness of the diamond layer is measured according to the following procedure. The diamond-coated tool is cut by a wire electric discharge machine along the normal line of the surface of the diamond layer, and a cross section is exposed. In the cross section, observation is performed using an SEM (scanning electron microscope, "JEM-2100F / Cs" (trademark) manufactured by JEOL Ltd.), and thus the thickness of the diamond layer is measured. Specifically, the observation magnification of the cross section sample is set to 5000 times, and the observation field area is set to 100 μm 2 The thickness of three places within the observation field is measured, and the average of the three places is taken as the thickness of the observation field. The average of the thicknesses of five observation fields is taken as the thickness of the diamond layer.

[0089] (Use)

[0090] The diamond-coated tool according to the present embodiment can be usefully used, for example, as a cutting tool such as an indexable cutting insert, a turning tool, a cutter, a drill, an end mill, and the like, and a wear-resistant tool such as a die, a bending die, a drawing die, a joining tool, and the like.

[0091] In the above, an aluminum alloy is described as the workpiece, but the workpiece is not limited thereto. As the workpiece, for example, a carbon fiber reinforced plastic (CFRP), titanium, a metal matrix composite, a ceramic, a ceramic matrix composite, a cemented carbide, and the like can be exemplified.

[0092] <Embodiment 2: Method for manufacturing diamond-coated tool>

[0093] The method for manufacturing the diamond-coated tool according to Embodiment 2 can include a step of preparing a substrate (hereinafter, also referred to as "substrate preparation step"), a step of forming a diamond layer on the substrate by a chemical vapor deposition method (hereinafter, also referred to as "diamond layer formation step"), and a step of obtaining a diamond-coated tool by performing oxygen ion etching on the diamond layer (hereinafter, also referred to as "oxygen ion etching step").

[0094] (Substrate preparation step)

[0095] As the substrate, the substrate of the above-described embodiment is prepared. It is preferable to perform a surface treatment such as a sandblasting treatment, an etching treatment, and the like on the substrate. Thereby, the oxide film and the contaminant on the surface of the substrate are removed. Further, the surface roughness of the substrate is increased, and thus the adhesion of the substrate to the diamond layer is improved.

[0096] As the sandblasting treatment, for example, SiC having a particle diameter of 30 μm can be projected to the substrate at a projection pressure of 0.15 to 0.35 MPa.

[0097] As for the etching treatment, for example, an acid solution treatment using 30% nitric acid or the like and an alkali treatment using sodium hydroxide or the like are performed.

[0098] (Diamond layer forming step)

[0099] Next, a seed crystal treatment is performed by immersing the above substrate in, for example, a 0.1 g / L aqueous solution of diamond seed crystals.

[0100] Next, a diamond layer is formed on the surface of the substrate on which the diamond seed crystals are seeded, by a CVD method. The CVD method can use a conventionally known CVD method. For example, a microwave plasma CVD method, a plasma jet CVD method, a hot filament CVD method, or the like can be used.

[0101] For example, a substrate can be arranged in a hot filament CVD device, and methane gas and hydrogen gas can be introduced into the device at a mixing ratio of 0.5:99.5 to 10:90 on a volume basis, and the substrate temperature can be maintained at 700°C or higher and 900°C or lower to form the diamond layer.

[0102] (Oxygen ion etching step)

[0103] Next, the above diamond layer is subjected to oxygen ion etching to obtain a diamond-coated tool. Generally, the skewness of the diamond layer formed by CVD is 0 or less. In the present embodiment, by subjecting the diamond layer formed by CVD to oxygen ion etching, the skewness Ssk of the surface of the diamond layer can be made greater than 0.

[0104] In addition, by performing the oxygen ion etching, the surface of the diamond layer is oxidized, the oxidation resistance of the diamond layer is improved, and in addition, by selectively etching the sp2 component of the surface, the wear resistance and the fusion bonding resistance of the diamond-coated tool are improved.

[0105] The method of the oxygen ion etching is not particularly limited, and a conventionally known method can be used.

[0106] The acceleration voltage at the time of the oxygen ion etching is preferably 3 kV or higher and 6 kV or lower. If the acceleration voltage is 3 kV or higher, the skewness Ssk of the diamond layer easily becomes greater than 0. If the acceleration voltage is 6 kV or lower, the oxygen content of the diamond layer becomes moderate, and the oxidation resistance of the diamond layer is easily improved.

[0107] The oxygen partial pressure at the time of the oxygen ion etching can be 0.001 Pa or higher and 1000 Pa or lower, 0.01 Pa or higher and 500 Pa or lower, 0.05 Pa or higher and 100 Pa or lower.

[0108] The treatment time of the oxygen ion etching can be 5 minutes or longer and 600 minutes or shorter, 10 minutes or longer and 450 minutes or shorter, 15 minutes or longer and 300 minutes or shorter.

[0109] Further, in Japanese Patent Application Publication No. 2001-501873 (Patent Literature 1), etching of a diamond layer is disclosed as a process for making the surface of the diamond layer smooth. Therefore, the etching conditions described in Japanese Patent Application Publication No. 2001-501873 (Patent Literature 1) are different from the conditions of the oxygen ion etching of the present disclosure, and cannot make the skewness Ssk of the diamond layer greater than 0.

[0110] <Note 1>

[0111] The skewness Ssk of the diamond layer of the diamond-coated tool of the present disclosure, which is prescribed by ISO 25178, is preferably greater than 0 and 1 or less.

[0112] The skewness Ssk of the diamond layer, which is prescribed by ISO 25178, is preferably 0.05 or more and 0.8 or less.

[0113] The skewness Ssk of the diamond layer, which is prescribed by ISO 25178, is preferably 0.1 or more and 0.6 or less.

[0114] <Note 2>

[0115] The surface roughness Ra of the diamond layer of the present disclosure, which is prescribed by JIS B 0601:2013, is preferably 0.01 μm or more and 0.5 μm or less.

[0116] The surface roughness Ra of the diamond layer, which is prescribed by JIS B 0601:2013, is preferably 0.05 μm or more and 0.45 μm or less.

[0117] The surface roughness Ra of the diamond layer, which is prescribed by JIS B 0601:2013, is preferably 0.1 μm or more and 0.4 μm or less.

[0118] <Note 3>

[0119] In the case where the Raman shift of the diamond layer of the present disclosure is determined to be 900 cm -1 or more and 2000 cm -1 or less, the ratio Id / Is of the peak area intensity Id of the diamond to the area intensity Is of the entire spectrum is preferably 0.08 or more and 0.5 or less.

[0120] The above ratio Id / Is is preferably 0.085 or more and 0.4 or less.

[0121] The above ratio Id / Is is preferably 0.09 or more and 0.3 or less.

[0122] <Note 4>

[0123] The oxygen content in the region R of the diamond layer of the present disclosure is preferably 20 atomic % or more and 90 atomic % or less.

[0124] The oxygen content is preferably 25 atomic % or more and 85 atomic % or less.

[0125] The oxygen content is preferably 30 atomic % or more and 80 atomic % or less.

[0126] <Note 5>

[0127] The thickness of the diamond layer of the present disclosure is preferably 1 μm or more and 40 μm or less.

[0128] The thickness of the diamond layer of the present disclosure is preferably 2 μm or more and 35 μm or less.

[0129] The thickness of the diamond layer of the present disclosure is preferably 3 μm or more and 30 μm or less.

[0130] <Note 6>

[0131] The manufacturing method of the diamond-coated tool of the present disclosure comprises:

[0132] a step of preparing a substrate;

[0133] a step of forming a diamond layer on the substrate by a chemical vapor deposition method; and

[0134] a step of obtaining a diamond-coated tool by performing oxygen ion etching on the diamond layer,

[0135] In the oxygen ion etching, the acceleration voltage of the ions is preferably 3 kV or more and 6 kV or less.

[0136] <Note 7>

[0137] The oxygen partial pressure during the oxygen ion etching is preferably 0.001 Pa or more and 1000 Pa or less.

[0138] The oxygen partial pressure during the oxygen ion etching is preferably 0.01 Pa or more and 500 Pa or less.

[0139] The oxygen partial pressure during the oxygen ion etching is preferably 0.05 Pa or more and 100 Pa or less.

[0140] <Note 8>

[0141] The processing time of the oxygen ion etching is preferably 5 minutes or more and 600 minutes or less.

[0142] The processing time of the oxygen ion etching is preferably 10 minutes or more and 450 minutes or less.

[0143] The treatment time of the above oxygen ion etching is preferably 15 minutes or more and 300 minutes or less.

[0144] The present embodiment will be further specifically described by examples. However, the present embodiment is not limited to these examples.

[0145] Example

[0146] [Samples 1 to 8]

[0147] [Production of diamond-coated tool]

[0148] [Preparation of substrate]

[0149] As the substrate, a cutting blade for an end mill of tool type AOET11T308PEFR-S was prepared, which was made of WC-6%Co (cemented carbide) and had a shape.

[0150] [Formation of diamond layer]

[0151] Next, the surface of the above substrate was subjected to seed crystal treatment with diamond powder. The seed crystal treatment was performed by immersing the substrate in a solution prepared by mixing diamond powder having an average particle diameter of 0.05 μm with water.

[0152] Next, the substrate subjected to the above seed crystal treatment was set in a hot filament CVD device, and a diamond layer was formed. The film formation conditions were as follows.

[0153] The wire current was controlled so that the substrate surface temperature became the temperature described in the column of "substrate temperature (°C)" of "CVD film formation conditions" of Table 1. The flow rates of methane and hydrogen were controlled so that the methane concentration became the concentration described in the column of "methane concentration (%) " of "CVD film formation conditions", and were supplied into the furnace. In all of the samples, the pressure at the time of film formation was set to 500 mPa, and film formation was performed until the film thickness of the diamond layer reached 10 μm.

[0154] For example, in Sample 1, the substrate temperature at the time of film formation was set to 750°C, the methane concentration was set to 1%, and the pressure was set to 500 mPa.

[0155] [Oxygen ion etching]

[0156] By subjecting the above diamond layer to oxygen ion etching, a diamond-coated tool was obtained for each sample. The conditions of the oxygen ion etching were as follows.

[0157] The acceleration voltage at the time of oxygen ion etching was as described in the column of "acceleration voltage (kV)" of "oxygen ion etching" of Table 1. The oxygen partial pressure was as described in the column of "oxygen partial pressure" of "oxygen ion etching" of Table 1. The time of oxygen ion etching was set to 30 minutes in all of the samples.

[0158] For example, in Sample 1, the oxygen ion etching was performed at an acceleration voltage of 3 kV, an oxygen partial pressure of 0.2 Pa for 30 minutes.

[0159] Table 1

[0160]

[0161] <evaluation>

[0162] (Maximum value of oxygen content in the region R, skewness Ssk, surface roughness Ra, ratio Id / Is)

[0163] For each of the diamond layers of the samples, the maximum value of the oxygen content in the region R, the skewness Ssk, the surface roughness Ra, and the ratio Id / Is were measured. The specific measurement methods are described in Embodiment 1, and thus the description thereof will not be repeated. The results are shown in the "Ssk", "Ra", "Id / Is", and "Maximum value of oxygen content (atomic %)" columns of "Diamond layer" of Table 1.

[0164] (cutting test)

[0165] The diamond-coated tools (cutting inserts) of each of the samples were attached to an end mill shank (steel, tool model WEZ11032E02, tool diameter 3 (two blades), and a cutting test was performed under the following conditions.

[0166] Workpiece: block of die-cast aluminum (ADC12) 300 mm x 150 mm x 50 mm

[0167] Cutting speed Vc: 1000 m / min

[0168] Feed amount Fz: 0.15 mm / t

[0169] Axial cut-in amount ap: 8 mm

[0170] Lateral cut-in amount ae: 3 mm

[0171] Cutting oil: Yes

[0172] In the above cutting test, the cutting distance until the maximum flank wear amount reached 0.01 mm was measured. The longer the cutting distance, the longer the tool life. The results are shown in the "Distance" column of "Cutting test" of Table 1.

[0173] <evaluation>

[0174] The diamond-coated tools of Samples 1 to 4 correspond to the examples. The surface-coated diamond-coated tools of Samples 5 to 8 correspond to the comparative examples. It was confirmed that the cutting distance was longer and the tool life was longer for Samples 1 to 4 (examples) than for Samples 5 to 8 (comparative examples).

[0175] In Test Samples 1 to 4, it is presumed that since Ssk of the diamond layer is greater than 0, cutting oil is easily held in the recesses of the surface at the time of cutting, and welding is not easily generated, and therefore tool life is long.

[0176] In Test Samples 5 to 8, it is presumed that since Ssk of the diamond layer is less than 0, cutting oil is difficult to be held on the surface of the diamond layer at the time of cutting, and welding is generated, and tool life is easily shortened.

[0177] The embodiments and examples of the present disclosure have been described as above, but it is also intended from the outset to appropriately combine or variously modify the configurations of the above-described embodiments and examples.

[0178] The embodiments and examples of the present disclosure should be considered in all respects as illustrative and not restrictive. The scope of the present invention is not represented by the above-described embodiments and examples, but by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0179] Explanation of Reference Signs

[0180] 1: substrate; 2: diamond layer; 10: diamond-coated tool; S: main surface S; Q: virtual surface Q; R: region R.

Claims

1. A diamond coated tool, wherein: The diamond coated tool comprises a substrate and a diamond layer disposed on the substrate. The skewness Ssk of the diamond layer as specified in ISO 25178 is greater than 0 and less than 0.6, The surface roughness Ra of the diamond layer as specified in JIS B 0601:2013 is 0.5 μm or less.

2. The diamond coated tool according to claim 1, wherein The Raman shift of the diamond layer was determined to be 900 cm -1 Above 2000cm -1 In the case of the following Raman spectrum, the ratio Id / Is of the peak area intensity Id of diamond to the area intensity Is of the entire spectrum is 0.08 or more.

3. The diamond coated tool according to claim 1 or 2, wherein: The diamond layer has an oxygen content of at least 20 atomic % in a region (R) surrounded by a primary surface (S) on the surface side of the diamond-coated tool and a virtual surface (Q) at a distance of 20 nm from the primary surface (S) toward the substrate side in a direction normal to the primary surface (S).

4. A method for manufacturing a diamond-coated tool, which is the method for manufacturing a diamond-coated tool according to any one of claims 1 to 3, wherein: The method for manufacturing the diamond coated tool comprises: The process of preparing the substrate; forming a diamond layer on the substrate by chemical vapor deposition; and a step of performing oxygen ion etching on the diamond layer to obtain a diamond-coated tool.

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