Coated cutting tool and cutting tool

Abstract

A coated tool based on an aspect of the present disclosure that is not limited has a substrate composed of a WC-based cemented carbide having WC particles and a binder phase, and a diamond film on the substrate. In a cross section orthogonal to a surface of the coated tool, the binder phase is less in content at a position closer to the surface of the substrate than at a central portion of the substrate. In an interface region between the substrate and the diamond film, in a case where the WC particles located at a position separated from the substrate are taken as free WC particles, the number of the free WC particles present per 10 μm of the interface length is four or less. A cutting tool based on an aspect of the present disclosure that is not limited has the above-described coated tool.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to Japanese Patent Application No. 2021-098119, filed on June 11, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to coated cutting tools and cutting tools. Background Technology

[0004] In diamond-coated cutting tools obtained by coating a tool substrate made of WC-based cemented carbide with a diamond film, various solutions have been proposed to improve the adhesion between the tool substrate and the diamond film.

[0005] For example, International Publication No. 2018 / 174139 (Patent Document 1) discloses a cutting tool that specifies the maximum height difference between the roughness and unevenness of the interface between the tool substrate and the diamond film, the maximum distance between the roughness and unevenness, the length of the area where the binder phase is removed, and the average grain size of the diamond crystals.

[0006] Furthermore, Japanese Patent No. 6733947 (Patent Document 2) discloses a diamond-coated tool with crystal grains obtained by the random crystal growth of a diamond layer near the substrate, so as to perform machining with a longer tool life in the high-efficiency machining of difficult-to-cut materials.

[0007] In the past, when diamond-coated tools were used for high-efficiency / high-precision cutting of difficult-to-cut materials, film peeling was prone to occur between the substrate and the diamond film during machining, resulting in deterioration of tool life and making it unsuitable for long-term stable machining. Summary of the Invention

[0008] A coated cutting tool based on an undefined aspect of this disclosure comprises: a substrate formed of a WC-based cemented carbide having WC particles and a binder phase; and a diamond film disposed on the substrate. In a cross-section orthogonal to the surface of the coated cutting tool, the content of the binder phase is low at a position closer to the surface of the substrate than at its central portion. In the interface region between the substrate and the diamond film, when the WC particles located at positions separated from the substrate are defined as free WC particles, the number of free WC particles present per 10 μm interface length is four or less.

[0009] Cutting tools based on an undefined aspect of this disclosure have the aforementioned coated tools. Attached Figure Description

[0010] Figure 1This is a diagram showing a coated cutting tool in an undefined aspect of this disclosure, and is a schematic cross-section.

[0011] Figure 2 This is a schematic diagram illustrating a film-forming apparatus used in the manufacture of a coated tool in an aspect not limited to this disclosure.

[0012] Figure 3 This is a side view showing a cutting tool (end mill) in an undefined aspect of this disclosure.

[0013] Figure 4 yes Figure 3 The cross-sectional view of section IV-IV in the cutting tool shown.

[0014] Figure 5 This is a side view showing a cutting tool (drill bit) in an undefined aspect of this disclosure.

[0015] Figure 6 yes Figure 5 The cutting tool shown is shown as a cross-sectional view of section VI-VI.

[0016] Figure 7 This is a perspective view showing a cutting tool (instrument drill bit) in an undefined aspect of this disclosure.

[0017] Figure 8 yes Figure 7 A perspective view of the cutting insert in the cutting tool shown.

[0018] Figure 9 yes Figure 8 The cutting insert shown is a cross-sectional view of section IX-IX. Detailed Implementation

[0019] Coated Cutting Tools

[0020] Hereinafter, a coating tool 1, which is not limited to one aspect of this disclosure, will be described in detail using the accompanying drawings. However, in the drawings referred to below, only the main components required for illustrating the embodiments are simplified for ease of explanation. Therefore, the coating tool 1 can include any constituent components not shown in the referenced drawings. In addition, the dimensions of the components in the drawings do not accurately represent the actual dimensions of the constituent components or the dimensional ratios of each component. These points are also the same for the cutting tools described later.

[0021] like Figure 1 As shown in the undefined example, the coated tool 1 may have a substrate 3 and a diamond film 5 on the substrate 3.

[0022] The matrix 3 may be composed of WC-based cemented carbide 7. WC-based cemented carbide 7 may be simply referred to as cemented carbide 7. Cemented carbide 7 has WC (tungsten carbide) particles 9 and a binder phase 11.

[0023] There can be multiple WC particles 9. WC particles 9 can also be referred to as hard particles. It should be noted that the cemented carbide 7 can have a hard phase containing multiple WC particles 9. The hard phase can contain at least one selected from the group consisting of carbides, nitrides, and carbonitrides of metals from Groups 4, 5, and 6 of the periodic table other than WC.

[0024] The average particle size of WC particles 9 is not limited to a specific value. For example, the average particle size of WC particles 9 can be greater than 0.3 μm and less than 2.0 μm. The average particle size of WC particles 9 can be determined by image analysis. In this case, the equivalent circle diameter can be used as the average particle size of WC particles 9. The determination of the average particle size of WC particles 9 can be performed in the following order. First, a scanning electron microscope (SEM) can be used to observe the cross-section of the substrate 3 at a magnification of 3000 to 5000 times, and an SEM image can be obtained. At least 50 WC particles 9 can be identified and extracted from the SEM image. Then, the average particle size of WC particles 9 can be determined by calculating the equivalent circle diameter using the image analysis software ImageJ (1.52).

[0025] The binder phase 11 can function to bond adjacent WC particles 9. Additionally, the binder phase 11 can also function to bond adjacent hard phases. The binder phase 11 can be composed of ferrous metals such as Co (cobalt) and Ni (nickel).

[0026] The diamond film 5 can cover the entire surface 13 of the substrate 3, or it can cover only a portion of it. When the diamond film 5 covers only a portion of the surface 13 of the substrate 3, it can also be said that the diamond film 5 is located on at least a portion of the substrate 3.

[0027] The diamond film 5 can be formed by chemical vapor deposition (CVD). In other words, the diamond film 5 can also be a CVD film.

[0028] The diamond film 5 is not limited to a specific thickness. For example, the thickness of the diamond film 5 can be set to be 3 μm or more and 45 μm or less. It should be noted that the thickness of the diamond film 5 can be measured, for example, by cross-sectional observation using an electron microscope. Examples of electron microscopes include SEM.

[0029] Here, in a cross-section orthogonal to the surface of the coated tool 1, the substrate 3 may have a lower content of binder phase 11 at a position closer to the surface 13 of the substrate 3 than the central part of the substrate 3. "Surface 13 of the substrate 3" can include not only the surface 13 itself, but also the surrounding area. That is, "surface 13 of the substrate 3" can be referred to as the area near the surface of the substrate 3. The area near the surface can refer to the region from the surface 13 of the substrate 3 to a depth of 10 μm. Alternatively, it can refer to the region from the uppermost WC particle 9 of the substrate 3 to the deepest diamond film 5 at the bottom of the substrate 3, along the thickness direction. A lower content of binder phase 11 means, for example, a lower content of binder phase 11 per unit area in the cross-section of the substrate 3. It should be noted that the content of binder phase 11 along a straight line can be evaluated using a so-called line analyzer.

[0030] "The central portion of the substrate 3" can be renamed as the central portion of the substrate 3 in the thickness direction. Alternatively, "the central portion of the substrate 3" could also be, for example, the portion including the rotation axis O described later (see [reference]). Figure 4 (etc.). Confirmation that the content of the binder phase 11 in the surface 13 of the substrate 3 is relatively low can be made, for example, by wavelength-dispersed EPMA (WDS).

[0031] When the WC particles 9 located at positions separated from the substrate 3 in the interface region S1 between the substrate 3 and the diamond film 5 are designated as free WC particles 15, the number of free WC particles 15 present per 10 μm interface length can be four or less. The interface length can refer to the length of a straight line drawn along the surface 13 of the substrate 3.

[0032] When free WC particles 15 that do not contact adjacent WC particles 9 are present in the interface region S1, it is difficult to obtain good adhesion of the diamond film 5. When there are four or fewer free WC particles 15 per 10 μm interface length, the diamond film 5 exhibits good adhesion. Therefore, the coated tool 1 with the above structure has a longer lifespan. It should be noted that the determination of free WC particles 15 can be performed, for example, by cross-sectional observation using an electron microscope. The cross-section can be a mirror.

[0033] The number of free WC particles 15 can be between 0 and two per 10 μm interface length. Furthermore, the substrate 3 can be a region S2 on the surface 13 of the substrate 3 where the content of the binder phase 11 in the central portion of the substrate 3 is set to 100%, and the content of the binder phase 11 is 15% or less. The lower limit of the binder phase 11 content in region S2 can be 0%. Confirmation that the binder phase 11 content in the surface 13 of the substrate 3 is 15% or less can be achieved, for example, by performing linear analysis from the central portion of the substrate 3 toward the surface 13 of the substrate 3 using wavelength dispersive EPMA (WDS).

[0034] Alternatively, cross-sectional observation can be performed using EPMA (WDS). For an image of an observation area extending 20 μm from the interface between the diamond film 5 and the substrate 3 towards the interior of the substrate 3 at a depth of 20 μm and parallel to the surface 13 of the substrate 3, in a region where the binder phase 11 content is low (i.e., less than 15%), the depth from the interface between the diamond film 5 and the substrate 3 can be measured at multiple locations (e.g., six locations). The depth (length) of the region S2 with low binder phase 11 content can be determined by averaging these values. Alternatively, the amount of binder phase 11 can be determined by measuring the cross-section of the sample at multiple locations (e.g., six locations) using Auger Electron Spectroscopy (AES) and averaging these values.

[0035] The length I of the region S2 with a low content of binder phase 11 can be greater than 1.0 μm and less than 5.0 μm. The length I of region S2 refers to the length in the direction perpendicular to the surface of the substrate 3.

[0036] Under the action of surface treatments described later, such as etching treatments based on acid solutions or alkaline solutions, the length I of the region S2 with a low content of binder phase 11 changes. When the length I is 1.0 μm or more, a good diamond film 5 can be formed, and the adhesion of the diamond film 5 is unlikely to decrease. Furthermore, when the length I is 5.0 μm or less, the interface between the substrate 3 and the diamond film 5 becomes less fragile, and it is difficult for cracks to form on the substrate 3 side, which is unlikely to be a cause of delamination of the diamond film 5. Therefore, the value of the length I can be set to 1.0 μm or more and 5.0 μm or less.

[0037] It should be noted that the region S2 with a low content of binder phase 11 can be referred to as the region S2 of the substrate 3 where the binder phase 11 has been removed. The removal of binder phase 11 can be achieved, for example, by removing the binder phase 11 contained in the substrate 3 under the action of an acid-based surface treatment. It should be noted that after the surface treatment, the substrate 3 is heated during the formation of the diamond film 5. Due to this heating, the binder phase 11 may temporarily reappear in a portion of the region where it has been removed. Therefore, the length I of the region S2 of the substrate 3 in the coated tool 1 where the binder phase 11 has been removed is sometimes shorter than the length of the region where the binder phase 11 has been removed by the acid solution.

[0038] The confirmation that the content of binder phase 11 in region S2 is relatively low can be performed in the same manner as the confirmation of the content of binder phase 11 in surface 13 of substrate 3. Region S2 may have multiple WC particles 9 and voids located between adjacent WC particles 9.

[0039] The average particle size of WC particles 9 in interface region S1 can be smaller than the average particle size of WC particles 9 inside the substrate 3 closer to interface region S1. Specifically, the average particle size of WC particles in interface region S1 can be smaller than 0.7 when the average particle size of WC particles inside the substrate 3 is set to 1. In this case, the diamond film 5 tends to exhibit good adhesion. When the size of WC particles 9 present in interface region S1 is relatively large, it may have a negative impact on the adhesion of the diamond film 5.

[0040] <Manufacturing Method of Coated Cutting Tools>

[0041] Next, a method for manufacturing a coated cutting tool, which is not limited to one aspect of this disclosure, will be described.

[0042] It should be noted that Patent Document 1 describes the process of performing alkaline etching and acid etching on a cemented carbide tool after grinding. However, in this method, after acid etching, unstable WC particles and free WC particles remain on the surface of the tool substrate. Subsequently, it describes ultrasonic treatment in a solution containing diamond powder to promote diamond nucleation, but does not mention removing unstable WC particles and free WC particles at the interface that has the greatest impact on the bonding strength of the diamond film relative to the substrate. Furthermore, Patent Document 2 describes a process of sandblasting in addition to etching. However, when sandblasting the hard substrate with abrasive grains, the sandblasting material penetrates the intergranular space and binder phase of the hard particles, becoming a factor that reduces the bonding strength in the subsequent formation of the diamond film.

[0043] In manufacturing coated cutting tools, the substrate can be prepared first. First, raw material powders such as WC powder, metallic Co powder, and Cr3C2 (chromium carbide) powder can be mixed to obtain a mixed powder. Next, this mixed powder can be shaped into a specified tool shape using known forming methods such as stamping, casting, extrusion, and cold isostatic pressing to obtain a molded body. Then, the obtained molded body can be fired in a vacuum or a non-oxidizing atmosphere to obtain the substrate in the shape of the cutting tool.

[0044] Next, acid or alkaline solutions can be used to treat the surface of the substrate. It should be noted that, for convenience, the substrate before surface treatment can be referred to as the untreated substrate, and the substrate after surface treatment can be referred to as the substrate.

[0045] First, the untreated substrate can be etched by sequentially immersing it in an alkaline solution and then an acidic solution. During this etching process, the amount of binder phase at the surface of the substrate tends to decrease compared to the central portion of the substrate.

[0046] Examples of alkaline solutions include Murakami reagent (a mixture of potassium hydroxide, potassium hexacyanoferrate (III), and pure water in a ratio of 10 g: 10 g: 100 ml). The immersion time of the untreated substrate in the alkaline solution can be 20 minutes or more but less than 50 minutes.

[0047] Additionally, examples of acid solutions include hydrochloric acid, persulfate, and nitric acid. The immersion time of the untreated substrate in the acid solution, for example, in the case of nitric acid (concentration 1 mol / L), can be 5 minutes or more but less than 30 minutes. Through surface treatment based on the acid solution, the binder phase in the substrate is removed from the surface of the substrate. When the surface treatment time is longer, the binder phase is removed to deeper locations.

[0048] When the processing time is set to 5 minutes or more, the length I of the region with less binder phase after diamond film formation tends to be 1.0 μm or more. Conversely, when the processing time is set to 30 minutes or less, the length I of the region with less binder phase after diamond film formation tends to be 5.0 μm or less. In coated cutting tools with this range of length I of less binder phase region, the substrate and diamond film tend to bond firmly.

[0049] It should be noted that, when performing acid-based surface treatments, the conditions shown below can be applied in an ultrasonic cleaner.

[0050] Output: 80W or more and 250W or less

[0051] Time: 5 minutes or more but less than 30 minutes

[0052] Ultrasonic cleaning can also be performed after surface treatment. During this ultrasonic treatment, WC particles that subsequently become free WC particles, generated by the surface treatment described above, can be removed. Depending on the conditions of the ultrasonic treatment, the number of free WC particles is easily reduced to four or less per 10 μm interface length.

[0053] First, distilled water or an organic solvent can be prepared and the untreated substrate can be immersed in a container under negative pressure. Furthermore, ultrasonic treatment can be performed, for example, under the conditions described below for ultrasonic cleaning.

[0054] Equipment: Ultrasonic disperser

[0055] Output: 600W and above

[0056] Time: 10 minutes or more but less than 120 minutes

[0057] Negative pressure conditions: 0.1–0.9 atmospheres

[0058] Next, a treatment solution can be prepared by adding diamond abrasive grains to an organic solvent, and this solution can be used to impregnate an untreated matrix. The average particle size of the diamond abrasive grains can be greater than 0.5 μm and less than 10 μm. The average particle size of the diamond abrasive grains can be a value determined by laser scattering.

[0059] Then, ultrasonic treatment can be performed while the untreated substrate is immersed in the treatment solution. Ultrasonic treatment can be performed, for example, under the following conditions.

[0060] Output: 250W or more but less than 500W

[0061] Time: 5 minutes or more but less than 30 minutes

[0062] Next, a diamond film can be formed on the obtained substrate. The diamond film can be formed using a hot-wire CVD method. Figure 2 An example of a film-forming method will be described.

[0063] like Figure 2 As shown in the undefined example, the film-forming apparatus 101 may have a reaction chamber 103. A sample stage 105 for placing the substrate 3 may be provided inside the reaction chamber 103. If the substrate 3 is rod-shaped, the substrate 3 may be arranged with its front end facing upwards.

[0064] A heater 107, such as a tungsten filament heater, can also be arranged around the substrate 3. The heater 107 can be electrically connected to a power supply 109 located outside the reaction furnace 103. Furthermore, the heater 107 can be supported by a support 111. Multiple heaters 107 can be used. The heaters 107 can be arranged to sandwich the substrate 3. The temperature of the substrate 3 arranged on the sample stage 105 can be adjusted by adjusting the arrangement of the heaters 107, the current supplied to the heaters 107, etc. For example, the temperature of the substrate 3 can be adjusted to, for example, above 850°C and below 930°C.

[0065] A gas supply port 113 and a gas exhaust port 115 can be provided in the reaction furnace 103. A reaction gas (film-forming gas) can be supplied from the gas supply port 113 into the vacuum-equipped reaction furnace 103. The reaction gas may contain, for example, hydrogen and methane gas. A diamond film 5 can be formed by blowing the reaction gas onto the substrate 3, thereby obtaining the coated tool 1.

[0066] It should be noted that the above-described manufacturing method is one example of a method for manufacturing the coated cutting tool 1. Therefore, the coated cutting tool 1 is not limited to the coated cutting tool manufactured by the above-described manufacturing method.

[0067] <Cutting Tools>

[0068] Next, regarding the cutting tool 31 of the unrestricted aspect of this disclosure, the case of the coated tool 1 described above will be taken as an example, and reference will be made to... Figures 3-9 A detailed explanation will be provided.

[0069] like Figures 3-9 As shown in the undefined example, the cutting tool 31 may have a coated tool 1. In this case, the coated tool 1 has a longer lifespan, thus enabling stable cutting operations over a long period.

[0070] like Figure 3 as well as Figure 4 As shown in the undefined example, the cutting tool 31 can be an end mill 41. The end mill 41 can be a bar shape extending from a first end 41a to a second end 41b along the axis of rotation O. The end mill 41 can have a shank portion 43 and a cutting portion 45 located closer to the first end 41a than the shank portion 43. The cutting portion 45 can have a first cutting edge 47 (bottom cutting edge) located on the first end 41a side, a second cutting edge 49 (outer peripheral cutting edge) extending toward the second end 41b, a groove 51 extending toward the second end 41b, and a central groove 53 located between the first cutting edge 47 and the groove 51.

[0071] like Figure 5 as well as Figure 6 As in the undefined example shown, the cutting tool 31 could also be a drill bit 61. The drill bit 61 could be a bar shape extending from a first end 61a to a second end 61b along the axis of rotation O. The drill bit 61 could have a shank portion 63 and a cutting portion 65 located closer to the first end 61a than the shank portion 63. The cutting portion 65 could have a cutting edge 67 located on the first end 61a side and a groove 69 extending toward the second end 61b.

[0072] like Figure 7 As shown in the undefined example, the cutting tool 31 can be a cutting insert 71. The cutting insert 71 can be a bar shape extending from a first end 73a to a second end 73b along the axis of rotation O, and has: a tool holder 73 having a tool groove 75 located on the side of the first end 73a; a slot 77 extending from the tool groove 75 toward the second end 73b; and a polygonal plate-shaped (quadrilateral plate-shaped) cutting insert 79 located in the tool groove 75.

[0073] like Figure 8 as well as Figure 9 As shown in the undefined example, the cutting insert 79 may have: a first face 81 (upper surface); a second face 83 (side surface) adjacent to the first face 81; a cutting edge 85 located at least a portion of the ridge portion of the first face 81 and the second face 83; and a through hole 87. Furthermore, the cutting insert 79 may have a coated tool 1.

[0074] It should be noted that the cutting tool 31 is not limited to the illustrated form. The cutting tool 31 can be, for example, a form used for turning. Examples of turning include internal diameter machining, external diameter machining, grooving, and end face machining.

[0075] The above examples illustrate a non-limiting aspect of the coated tool 1 and the cutting tool 31 of this disclosure, but this disclosure is not limited to the above embodiments. Of course, any method is possible as long as it does not depart from the spirit of this disclosure.

[0076] For example, in the unlimited embodiments described above, the case of using the coated tool 1 as a cutting tool 31 was used as an example, but the coated tool 1 can also be applied to other uses. Other uses include, for example, sliding parts, wear-resistant parts such as molds, digging tools, cutting tools such as blades, and impact-resistant parts.

[0077] The present disclosure will now be described in detail with reference to the following embodiments, but the present disclosure is not limited to the following embodiments.

[0078] Example

[0079] [Samples No. 1~11]

[0080] <Making Coated Knives>

[0081] First, a substrate is prepared. Specifically, 7.0% by mass of metallic Co powder, 0.8% by mass of Cr3C2 powder, and the remainder of WC powder with an average particle size of 0.5 μm are added and mixed, shaped into a cylindrical form, and then fired. Then, an untreated substrate in the shape of an end mill (10 mm diameter, 30 mm cutting edge, 4 cutting edges) is produced through centerless machining and edge-sharpening processes.

[0082] Next, the surface of the untreated substrate was surface-treated. Specifically, the untreated substrate was etched by sequentially immersing it in an alkaline solution (20–45 minutes in Murakami reagent) and an acid solution (20 minutes in 1 mol / L nitric acid). It should be noted that the specific immersion times in the alkaline solution are shown in the alkaline treatment column of Table 1.

[0083] Next, the untreated substrate was immersed in distilled water in a container filled with distilled water under reduced pressure to atmospheric pressure or a negative pressure of 0.5 atmospheres, and then subjected to ultrasonic treatment. The ultrasonic treatment was performed under the conditions of ultrasonic output, ultrasonic time, and presence or absence of negative pressure conditions (negative pressure treatment) as shown in the cleaning treatment column of Table 1.

[0084] Next, diamond abrasive grains with an average particle size of 5 μm were added to a treatment solution containing an organic solvent and impregnated onto the untreated substrate. Ultrasonic treatment was then performed using an ultrasonic cleaner manufactured by Otari at an output of 400W for 20 minutes.

[0085] The substrate that has undergone the above treatment is configured in Figure 2 The film-forming apparatus shown deposits a diamond film on the surface of a substrate using a hot-wire CVD method. The film-forming apparatus has a diameter of... The interior of the 20cm high reaction furnace is equipped with roughness. The tungsten filaments (heater) were used. Specifically, two filaments at different distances from the substrate were grouped together, with one group positioned at the front end and two groups positioned on the side, sandwiching the substrate, for a total of six filaments. The film formation temperature was adjusted to 900°C. The end-mill shaped substrate was positioned upright with the front end facing upwards. Then, in a vacuum, a reaction gas composition of methane gas (4% by volume) + hydrogen gas (remaining) was introduced into the interior of the reaction furnace through the gas supply port, and a diamond film was formed.

[0086] <Evaluation>

[0087] For the obtained coated cutting tools, cutting tests were conducted under the conditions shown below, and the machining distance and the presence or absence of delamination at the tool tip after the test were evaluated. The cutting test was conducted with a maximum machining distance of 50 m and a pass length of 5 m, until delamination of the diamond film was observed at the tool tip. For samples where delamination was observed, the number of cutting edges that produced delamination was evaluated. The results are shown in Table 1.

[0088] (Cutting test conditions)

[0089] Tool shape: 10mm cutting diameter, 4-flute end mill

[0090] Cutting method: Square shoulder machining

[0091] Workpiece to be machined: CFRP

[0092] Speed: 8000 rpm

[0093] Feed rate: 0.02mm / blade

[0094] Cutting depth: 5mm longitudinally, 5mm transversely

[0095] Cutting condition: Dry

[0096] [Table 1]

[0097]

[0098] It is known that the number of free WC particles present per 10 μm interface length is less than four. The coated cutting tool of this disclosure has excellent machining performance.

[0099] The substrates of the coated cutting tools disclosed herein, namely samples No. 1-3, 5-7, 9-10, have a lower content of binder phase at the surface of the substrate compared to the central portion of the substrate. This confirmation was performed using the aforementioned WDS.

[0100] For samples No. 1 to 3, 5 to 6, and 9 to 10, where the number of free WC particles is 0 or more and less than two, the matrix surface has a region with a low binder phase content, where the binder phase content in the central part of the matrix is ​​less than 15%. The length of this region with low binder phase content is 1.0 μm or more and 5.0 μm or less. These confirmations were performed using WDS and AES as described above.

[0101] The "number of free WC particles" shown in Table 1 was determined using cross-sectional observations via SEM. Additionally, the "WC particle size ratio in the interface region" shown in Table 1 is the ratio of the average particle sizes of WC particles in the interface region, assuming the average particle size of WC particles inside the matrix is ​​set to 1. The average particle size of WC particles contained in the matrix was determined using the image analysis described above.

[0102] Explanation of reference numerals in the attached figures

[0103] 1··· Coated cutting tools

[0104] 3···Matrix

[0105] 5. Diamond film

[0106] 7···WC-based cemented carbide

[0107] 9···WC particles

[0108] 11···Binder Phase

[0109] 13···The surface of the substrate

[0110] 15···Free WC particles

[0111] 31···Cutting tools

[0112] 41··· End mill

[0113] 41a··First End

[0114] 41b··Second End

[0115] 43···Handle

[0116] 45···Cutting section

[0117] 47···First Blade

[0118] 49···Second Blade

[0119] 51··· groove

[0120] 53···Central Groove

[0121] 61··· Drill Bit

[0122] 61a··First End

[0123] 61b··Second End

[0124] 63···Handle

[0125] 65···Cutting section

[0126] 67··· Cutting edge

[0127] 69··· groove

[0128] 71···Insert Drill Bits

[0129] 73··· Knife Holder

[0130] 73a··First End

[0131] 73b··Second End

[0132] 75··· Tool Groove

[0133] 77··· groove

[0134] 79··· Cutting inserts

[0135] 81···First Page

[0136] 83···Second page

[0137] 85··· Cutting edge

[0138] 87··· Through hole

[0139] 101··· Film Forming Device

[0140] 103···Reaction Furnace

[0141] 105··· Sample Stage

[0142] 107··· Heater

[0143] 109··· Power Supply

[0144] 111···Support body

[0145] 113···Gas Supply Port

[0146] 115···Gas exhaust port

[0147] S1··· Interface Area

[0148] S2... region with low binder phase content

[0149] I···Length

[0150] O··· Rotation axis.

Claims

1. A coated tool having: a substrate composed of a WC-based cemented carbide having WC grains and a binder phase; and a diamond film on the substrate, wherein, in a cross section orthogonal to a surface of the coated tool, the binder phase is less in content at a position closer to the surface of the substrate than at a central portion of the substrate, in an interface region between the substrate and the diamond film, in a case where a WC grain located at a position separated from the substrate is taken as a free WC grain, the number of the free WC grains present per 10 μm of interface length is four or less, and in a case where an average grain diameter of a WC grain inside the substrate closer to the substrate than the interface region is taken as 1, an average grain diameter of a WC grain in the interface region is less than 0.

7.

2. The coated tool according to claim 1, wherein, the number of the free WC grains is zero or less and two or less, the substrate has a region in which the binder phase is less in content in the surface of the substrate than 15% of the content of the binder phase at the central portion of the substrate, and a length of the region in which the binder phase is less in content is 1.0 μm or more and 5.0 μm or less.

3. A cutting tool, wherein, the cutting tool has the coated tool according to claim 1 or 2. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images