Single-crystal diamond material and tool

Abstract

A single-crystal diamond material comprising a single-crystal diamond and a modified portion present in an outer shell of the single-crystal diamond, the nitrogen-atom content of the single-crystal diamond, based on atomic number, being 1 ppm to 2,000 ppm, wherein, in an inner-shell electron excitation spectrum for the modified portion of the single-crystal diamond material, obtained by electron energy loss spectroscopy using a transmission electron microscope, the ratio Iπ* / Iσ* of the maximum intensity Iπ* of a π* peak present in the energy loss amount range of 285 eV ± 5 eV to the maximum intensity Iσ* of a σ* peak present in the energy loss amount range of 291 eV ± 5 eV is 0.15 or more, and the percentage {N1 / (N1+N2)}×100 of the number N1 of first carbon atoms constituting amorphous carbon to the total N1+N2 of the number N1 of first carbon atoms and the number N2 of second carbon atoms constituting graphite in the modified portion is 90% or more.

Description

Single crystal diamond materials and tools

[0001] The present disclosure relates to single crystal diamond materials and tools.

[0002] Single crystal diamond has extremely high fracture strength and excellent wear resistance, and is therefore used as a material for various cutting tools (see, for example, Patent Document 1).

[0003] International Publication No. 2022 / 118461

[0004] The single crystal diamond material of the present disclosure is a single crystal diamond material comprising a single crystal diamond and an altered portion present on the outer periphery of the single crystal diamond, wherein the nitrogen atom content of the single crystal diamond is 1 ppm or more and 2000 ppm or less based on the atomic number, and the single crystal diamond material has an energy loss of π in the range of 285 eV±5 eV in a core electron excitation spectrum obtained by electron energy loss spectroscopy using a transmission electron microscope of the altered portion. ＊ Maximum intensity of the peak Iπ ＊ and σ in the range of energy loss 291±5 eV. ＊ Maximum intensity of the peak Iσ ＊ The ratio Iπ ＊ / Iσ ＊ is 0.15 or more, and in the altered portion, the percentage {N1 / (N1+N2)}×100 of the number N1 of primary carbon atoms to the sum N1+N2 of the number N1 of primary carbon atoms constituting amorphous carbon and the number N2 of secondary carbon atoms constituting graphite is 90% or more.

[0005] Fig. 1 is a schematic cross-sectional view of a single crystal diamond material according to embodiment 1. Fig. 2 is a schematic cross-sectional view showing an example of a sample chamber configuration used in producing a single crystal diamond according to an embodiment of the present disclosure. Fig. 3 is a schematic cross-sectional view of a wire drawing die according to an embodiment of the present disclosure.

[0006] [Problem to be Solved by the Present Disclosure] In recent years, there has been an increasing need for fine machining of workpieces and machining into complex shapes. One way to address this situation is to make the shape of the tool finer and more complex. Even for tools using single-crystal diamond material as the material, there is a demand for single-crystal diamond material with improved machinability in order to achieve the finer and more complex shape of the tool.

[0007] Therefore, an object of the present disclosure is to provide a single crystal diamond material with improved machinability, and a tool equipped with the single crystal diamond material.

[0008] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a single crystal diamond material with improved machinability, and a tool including the single crystal diamond material.

[0009] [Explanation of the embodiment of the present disclosure] First, the embodiments of the present disclosure will be listed and explained. (1) The single crystal diamond material of the present disclosure is a single crystal diamond material comprising a single crystal diamond and an altered portion present on the outer periphery of the single crystal diamond, wherein the nitrogen atom content of the single crystal diamond is 1 ppm or more and 2000 ppm or less based on the number of atoms, and the single crystal diamond material has an energy loss of π in the range of 285 eV±5 eV in a core electron excitation spectrum obtained by electron energy loss spectroscopy using a transmission electron microscope of the altered portion. ＊ Maximum intensity of the peak Iπ ＊ and σ in the range of energy loss 291±5 eV. ＊ Maximum intensity of the peak Iσ ＊ The ratio Iπ ＊ / Iσ ＊ is 0.15 or more, and in the altered portion, the percentage {N1 / (N1+N2)}×100 of the number N1 of primary carbon atoms to the sum N1+N2 of the number N1 of primary carbon atoms constituting amorphous carbon and the number N2 of secondary carbon atoms constituting graphite is 90% or more.

[0010] According to the present disclosure, it is possible to provide a single crystal diamond material with improved machinability, and a tool including the single crystal diamond material.

[0011] (2) In the above (1), the surface of the single crystal diamond material may include a first region, and the maximum height Sz of the first region as defined in JIS B 0681-2:2018 may be 60 nm or more.

[0012] This makes it possible to improve the adhesive strength between the single crystal diamond material and the bonding material when a tool is produced by fixing the single crystal diamond material to a substrate via a bonding material.

[0013] (3) In the above (2), the first region may have an arithmetic mean height Sa of 3 nm or more as defined in JIS B 0681-2:2018, which further improves the adhesion between the single crystal diamond material and the bonding material.

[0014] (4) In any of the above (1) to (3), the surface of the single crystal diamond material may include a recess, and the maximum thickness of the altered portion present in the recess may be 3 nm or more.

[0015] This further improves the workability of the single crystal diamond material.

[0016] (5) In any one of (1) to (4) above, the coverage of the single crystal diamond by the altered portion may be 1% or more, which further improves the workability of the single crystal diamond material.

[0017] (6) In any of the above (1) to (5), in the single crystal diamond, the number of nitrogen atoms in the C center, N Ｃ The total number of nitrogen atoms, N ＡＬＬ and the number N of nitrogen atoms in the C center Ｃ Difference with N ＡＬＬ -N Ｃ The proportion of (N ＡＬＬ -N Ｃ ) / N Ｃ is 1 or more and 10 ５ It may be the following:

[0018] This improves the wear resistance and chipping resistance of the single crystal diamond material.

[0019] (7) A tool according to the present disclosure is a tool comprising the single crystal diamond material according to any one of (1) to (6) above. According to the present disclosure, it is possible to provide a tool having a fine and complex shape.

[0020] (8) In the above (7), the tool may be a cutting tool, a grinding tool, a wear-resistant tool, or a wire drawing tool. According to the present disclosure, it is possible to provide a tool having a fine and complex shape.

[0021] [Details of the embodiments of the present disclosure] Specific examples of the single crystal diamond material and tool of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference symbols represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for the sake of clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0022] In the present disclosure, the notation in the form of "A to B" means A or more and B or less, and when no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0023] In the present disclosure, when one or more numerical values ​​are listed as the lower limit and the upper limit of a numerical range, the combination of any one numerical value listed as the lower limit and any one numerical value listed as the upper limit is also considered to be disclosed.

[0024] [Embodiment 1: Single Crystal Diamond Material] A single crystal diamond material according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 1") is a single crystal diamond material comprising a single crystal diamond and an altered portion present on the outer periphery of the single crystal diamond, wherein the nitrogen atom content in the single crystal diamond is 1 ppm or more and 2000 ppm or less based on the number of atoms, and the single crystal diamond material exhibits a π energy loss in the range of 285 eV±5 eV in a core electron excitation spectrum of the altered portion obtained by electron energy loss spectroscopy using a transmission electron microscope.＊ Maximum intensity of the peak Iπ ＊ and σ in the range of energy loss 291±5 eV. ＊ Maximum intensity of the peak Iσ ＊ The ratio Iπ ＊ / Iσ ＊ is 0.15 or more, and in the altered portion, the percentage {N1 / (N1+N2)}×100 of the number N1 of primary carbon atoms to the sum N1+N2 of the number N1 of primary carbon atoms constituting amorphous carbon and the number N2 of secondary carbon atoms constituting graphite is 90% or more.

[0025] <Configuration of single crystal diamond material> Figure 1 is a schematic cross-sectional view of a single crystal diamond material of embodiment 1. As shown in Figure 1, the single crystal diamond material 21 of embodiment 1 comprises a single crystal diamond 22 and an altered portion 27 present on the outer periphery of the single crystal diamond 22.

[0026] The shape of the single crystal diamond 22 is not particularly limited and can be appropriately selected depending on the application. The shape of the single crystal diamond 22 may be, for example, a flat plate, a prism, a pyramid, a truncated pyramid, or a polyhedron. The size of the single crystal diamond material of the first embodiment is not particularly limited, but may be, for example, 0.1 mm ３ ~1000mm ３ may be.

[0027] The altered region 27 is present in the outer periphery of the single crystal diamond 22. The altered region 27 can be present in at least a part of the outer periphery of the single crystal diamond 22. The altered region 27 may be present so as to cover a part of the outer periphery of the single crystal diamond 22, or may be present so as to cover the entire outer periphery of the single crystal diamond 22. A plurality of altered regions 27 may be scattered on the outer periphery of the single crystal diamond 22. The outer periphery of the single crystal diamond 22 and the altered region 27 may be in contact with each other. A transition region connecting the single crystal diamond 22 and the altered region 27 may be present between the single crystal diamond 22 and the altered region 27, as long as it does not impair the effects of the present disclosure.

[0028] <Nitrogen content> The nitrogen atom content based on the atomic number of the single crystal diamond of embodiment 1 (hereinafter also referred to as "nitrogen content") is 1 ppm or more and 2000 ppm or less. If the nitrogen content is 1 ppm or more, it is easy to adjust the nitrogen content in the manufacturing process of the single crystal diamond material of embodiment 1. If the nitrogen content is 2000 ppm or less, crystal defects and distortion are reduced, and a decrease in the strength of the single crystal diamond material is suppressed. The nitrogen content of the single crystal diamond may be 3 ppm or more and 1400 ppm or less, 10 ppm or more and 800 ppm or less, or 30 ppm or more and 300 ppm or less.

[0029] In the present disclosure, the nitrogen atom content of a single crystal diamond based on the atomic number is measured by secondary ion mass spectrometry (SIMS). Measurement points are any five points on the single crystal diamond. In the present disclosure, the average of the five measured points corresponds to the nitrogen atom content of the single crystal diamond based on the atomic number.

[0030] <Altered portion> In the single crystal diamond material of embodiment 1, in the core electron excitation spectrum obtained by electron energy loss spectroscopy (hereinafter also referred to as "TEM-EELS") using a transmission electron microscope for the altered portion, the amount of energy loss is in the range of 285 eV±5 eV. ＊ Maximum intensity of the peak Iπ ＊ and σ in the range of energy loss 291±5 eV. ＊ Maximum intensity of the peak Iσ ＊ The ratio Iπ ＊ / Iσ ＊ is 0.15 or more, and in the altered portion, the percentage {N1 / (N1+N2)}×100 of the number N1 of primary carbon atoms to the sum N1+N2 of the number N1 of primary carbon atoms constituting amorphous carbon and the number N2 of secondary carbon atoms constituting graphite is 90% or more.

[0031] In the core electron excitation spectrum obtained by the TEM-EELS method in the altered area, the amount of energy loss is in the range of 285 eV ± 5 eV. ＊The peak is derived from the π bond of carbon, and exists in the range of energy loss 291±5 eV. ＊ The peak is a peak derived from the σ bond of carbon. ＊ / Iσ ＊ is 0.15 or more indicates that the ratio of carbon π bonds to carbon σ bonds in the altered portion of the single crystal diamond material of embodiment 1 is a predetermined amount or more.

[0032] The carbon atoms having a π bond present in the altered portion include carbon atoms constituting amorphous carbon (also referred to as "primary carbon atoms" in the present disclosure) and carbon atoms constituting graphite (also referred to as "secondary carbon atoms" in the present disclosure).

[0033] In the altered portion of the single crystal diamond of embodiment 1, the percentage of the number of primary carbon atoms N1 relative to the sum N1+N2 of the number of primary carbon atoms N1 constituting amorphous carbon and the number of secondary carbon atoms N2 constituting graphite, {N1 / (N1+N2)}×100, is 90% or more. This indicates that 90% or more of the carbon atoms having π bonds present in the altered portion exist as amorphous carbon. Amorphous carbon has a high absorption rate for lasers with wavelengths of 355 nm to 1064 nm, which are used in processing single crystal diamonds, compared to diamond and graphite.

[0034] In the core electron excitation spectrum obtained by the TEM-EELS method in the altered part of the single crystal diamond material, the ratio Iπ ＊ / Iσ ＊ is 0.15 or more and the percentage {N1 / (N1+N2)}×100 is 90% or more, the amorphous carbon with high laser absorption rate present on the surface of the single crystal diamond material improves the processability when laser processing the single crystal diamond material.

[0035] In the present disclosure, the presence of an altered portion in a single crystal diamond material is indicated by the ratio Iπ ＊ / Iσ ＊and the percentage {N1 / (N1+N2)}×100 in the altered portion.

[0036] <Ratio Iπ in the core electron excitation spectrum obtained by TEM-EELS in the altered area ＊ / Iσ ＊ Measurement of the ratio Iπ in the core electron excitation spectrum obtained by the TEM-EELS method in the altered part of the single crystal diamond material ＊ / Iσ ＊ The specific measurement method is as follows:

[0037] Step A1: A single crystal diamond material is sliced ​​using an argon ion slicer in a plane parallel to the normal direction of the surface to obtain a measurement sample with a thickness of 3 to 100 nm. The measurement sample is observed at 50,000 to 500,000 magnifications using a transmission electron microscope (TEM, JEOL Ltd., "JEM-2100F / Cs" (trademark)) to obtain a bright-field image of the single crystal diamond material.

[0038] Step A2. Next, identify the area corresponding to the altered portion in the bright-field image. In the bright-field image, the single crystal diamond and the altered portion can be distinguished, for example, by the difference in contrast. If an area with a contrast different from that of the single crystal diamond is confirmed on the surface of the single crystal diamond, this area is considered to be the area corresponding to the altered portion. The following measurements are carried out in the area corresponding to the altered portion in the bright-field image, which is estimated to be 3 nm or more thick.

[0039] Step A3: Starting from the surface of the region corresponding to the altered portion, a measurement point is set within a distance of 2 nm to 3 nm along the normal direction of the surface of the single crystal diamond material, and an electron energy loss spectroscopy (EELS) method is applied to observe the energy loss (K edge) associated with the excitation of carbon K-shell electrons by scanning an observation spot with a diameter of 1 nm in a direction parallel to the surface of the single crystal diamond material by 100 nm. As a result, a core electron excitation spectrum of around 300 eV associated with the excitation of carbon K-shell electrons at the measurement point is obtained.

[0040] Step A4. In the core electron excitation spectrum at the measurement point, the energy loss amount is within the range of 285 eV ± 5 eV. ＊ Maximum intensity of the peak Iπ ＊ and σ in the range of energy loss 291±5 eV. ＊ Maximum intensity of the peak Iσ ＊ and obtain Iπ ＊ Iσ ＊ By dividing by, the ratio Iπ ＊ / Iσ ＊ Ask for.

[0041] Step A5: The above measurement is performed at five measurement points that do not overlap each other. At all five measurement points, the ratio Iπ ＊ / Iσ ＊ When the ratio Iπ is 0.15 or more, the ratio Iπ in the core electron excitation spectrum obtained by the TEM-EELS method in the region corresponding to the altered portion ＊ / Iσ ＊ is judged to be 0.15 or more.

[0042] <<Measurement of percentage {N1 / (N1+N2)}×100 in the affected area>> Step B1. Next, the ratio Iπ is calculated by the above steps A1 to A4. ＊ / Iσ ＊ At each of five measurement points set in the region corresponding to the altered portion where it is determined that π is 0.15 or more, ＊ The peaks are separated into peaks derived from amorphous carbon and peaks derived from graphite. The five measurement points are the same as the five measurement points set in step A5 above.

[0043] Step B2. At each measurement point, the maximum intensity Iπ is calculated based on the state separation result. ＊ The percentage of the number N1 of primary carbon atoms to the sum N1+N2 of the number N1 of primary carbon atoms constituting amorphous carbon and the number N2 of secondary carbon atoms constituting graphite in the amount of energy loss indicated above is calculated as {N1 / (N1+N2)}×100.

[0044] If the percentage {N1 / (N1+N2)}×100 is 90% or more at all five measurement points, the percentage {N1 / (N1+N2)}×100 of the region corresponding to the measured altered part is determined to be 90% or more. In other words, the region corresponding to the altered part identified in step B1 is determined to be the region corresponding to the ratio Iπ in the core electron excitation spectrum obtained by the TEM-EELS method. ＊ / Iσ ＊ is 0.15 or more and the percentage {N1 / (N1+N2)}×100 is 90% or more, it is determined to be an altered part, and it is confirmed that the single crystal diamond material being measured has an altered part.

[0045] As long as measurements are taken on the same single crystal diamond material, the ratio Iπ can be obtained by acquiring multiple bright-field images that do not overlap each other and changing the measurement point in the region corresponding to the altered portion in each bright-field image. ＊ / Iσ ＊ It has been confirmed that there is almost no variation in the measurement results of the percentage {N1 / (N1+N2)}×100.

[0046] In the altered portion of the single crystal diamond material of embodiment 1, the ratio Iπ ＊ / Iσ ＊ is 0.15 or more, and may be 0.17 or more, or may be 0.19 or more.

[0047] In the altered portion of the single crystal diamond material of embodiment 1, the percentage {N1 / (N1+N2)}×100 is 90% or more, or alternatively 93% or more, or 96% or more, or alternatively 99% or more.

[0048] <Thickness of the altered portion> The surface of the single crystal diamond material of embodiment 1 includes recesses, and the maximum thickness of the altered portion present in the recesses is 3 nm or more, and may be 3 nm or more and 100 nm or less, 6 nm or more and 100 nm or less, 9 nm or more and 100 nm or less, or 10 nm or more and 100 nm or less.

[0049] In the present disclosure, the method for measuring the maximum thickness of an altered portion present in a recess in a single crystal diamond material is as follows.

[0050] The above ratio Iπ ＊ / Iσ＊ A bright-field image of the single crystal diamond material is obtained using the same method as measurement procedure A1. In the bright-field image, recesses in the single crystal diamond material are identified. Here, recesses are defined as areas that are recessed from the mean line of the surface roughness curve of the single crystal diamond material in the bright-field image of the single crystal diamond material. In each recess, the ratio Iπ is calculated at each of a plurality of measurement points set at 1 nm intervals along the normal direction of the surface of the single crystal diamond material, starting from the surface of the region corresponding to the altered part. ＊ / Iσ ＊ and measure the percentage {N1 / (N1+N2)} x 100. Ratio Iπ ＊ / Iσ ＊ The method for measuring the percentage {N1 / (N1+N2)} x 100 is the same as the method for confirming that the single crystal diamond material has an altered portion. The measurement area is appropriately set depending on the thickness of the area corresponding to the altered portion. For example, the measurement is performed in an area up to a distance of about 100 nm from the surface.

[0051] ratio Iπ ＊ / Iσ ＊ Of the measurement points where N1 / (N1+N2)}×100 is 90% or greater and N1 / (N1+N2) is 0.15 or greater, the measurement point A that is furthest from the surface is identified. For each recess, the distance between the surface and measurement point A is determined. In the present disclosure, the distance between the surface and measurement point A corresponds to the maximum thickness of the altered zone present in the recess of the single crystal diamond material.

[0052] In the single crystal diamond material of embodiment 1, the maximum thickness of the altered portion present in the region other than the recess may be less than the maximum thickness of the altered portion present in the recess, or may be smaller than the maximum thickness of the altered portion present in the recess.

[0053] <<Coverage of the altered portion>> In the single crystal diamond material of embodiment 1, the coverage of the altered portion of the single crystal diamond is 1% or more, and may be 3% or more and 100% or less, or 5% or more and 100% or less.

[0054] In the present disclosure, the method for measuring the coverage of a single crystal diamond by an altered portion is as follows.

[0055] For a single crystal diamond material that has been confirmed to have an altered portion, three non-overlapping bright-field images are acquired. The bright-field images are obtained by dividing the image by the ratio Iπ ＊ / Iσ ＊ The bright-field images are obtained in the same manner as in measurement procedure A1. In each bright-field image, the percentage (L1 / LA) x 100 of the length L1 of the altered portion in contact with the outer periphery of the single crystal diamond relative to the entire length LA of the outer periphery of the single crystal diamond is measured. The average of the percentages (L1 / LA) x 100 of the three bright-field images is calculated. In the present disclosure, this average corresponds to the coverage rate of the altered portion of the single crystal diamond in the single crystal diamond material. Note that, if the boundary between the single crystal diamond and the altered portion is not clear in the bright-field image, the bright-field image may be subjected to a binarization process, and the average of the percentage (L1 / LA) x 100 may be measured in the image after the binarization process in which the single crystal diamond and the altered portion are clearly distinguished.

[0056] It has been confirmed that, as long as measurements are taken on the same single-crystal diamond material, there is almost no variation in the measurement results even if the location at which the bright-field image is taken is changed.

[0057] When the shape of the single crystal diamond material is a substrate including a first main surface and a second main surface opposite the first main surface, the entire first main surface and the entire second main surface may each be an altered portion.

[0058] <Maximum height Sz and arithmetic mean height Sa> The surface of the single crystal diamond material of embodiment 1 includes a first region, and the maximum height Sz of the first region as defined in JIS B 0681-2: 2018 may be 60 nm or more. As a result, because the surface of the single crystal diamond material has appropriate irregularities, when the single crystal diamond material is fixed to a substrate via a bonding material, the adhesion between the single crystal diamond material and the bonding material is improved.

[0059] From the viewpoint of ease of material placement, the upper limit of the maximum height Sz of the first region may be 500 nm or less, 60 nm or more and 500 nm or less, 80 nm or more and 400 nm or less, or 100 nm or more and 300 nm or less.

[0060] The arithmetic mean height Sa of the first region may be 3 nm or more from the viewpoint of improving the adhesion between the single crystal diamond material and the bonding material. The upper limit of the arithmetic mean height Sa of the first region is preferably 100 nm or less from the viewpoint of ease of material installation. The arithmetic mean height Sa of the first region may be 3 nm or more and 100 nm or less, 5 nm or more and 80 nm or less, 5 nm or more and 60 nm or less, or 5 nm or more and 40 nm or less.

[0061] The arithmetic mean height Sa and maximum height Sz defined in JIS B 0681-2:2018 (Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms, definitions and surface texture parameters) correspond to the arithmetic mean height Sa and maximum height Sz defined in ISO 25178-2:2012 (Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms, definitions and surface texture parameters (MOD)).

[0062] In the present disclosure, whether the surface of a single crystal diamond material includes a first region is confirmed by the following procedure.

[0063] The surface of the single crystal diamond material is divided into rectangular unit areas of 10 μm × 10 μm, and the maximum height Sz is measured for each unit area. Depending on the shape of the surface of the single crystal diamond material, it may not be possible to divide the surface into an integral number of unit areas, resulting in a remainder. In such cases, only the unit areas are measured, and the remainder areas are excluded from the measurement target.

[0064] When a unit region having a maximum height Sz of 60 nm or more is present, it is confirmed that the surface of the single crystal diamond material includes a first region. ２ That's all.

[0065] In the present disclosure, the arithmetic mean height Sa and maximum height Sz of the first region are measured by the following procedure. On the surface of a single crystal diamond material, all unit regions A having a maximum height Sz of 60 nm or more are identified. The arithmetic mean height Sa and maximum height Sz are measured based on all unit regions A. The unit regions A may or may not be in contact with each other. In the present disclosure, the arithmetic mean height Sa measured based on all unit regions A corresponds to the arithmetic mean height Sa of the first region. In the present disclosure, the maximum height Sz measured based on all unit regions A corresponds to the maximum height Sz of the first region.

[0066] In the present disclosure, the position and size of the first region on the surface of the single crystal diamond material can be set appropriately depending on the application of the single crystal diamond material. For example, when the single crystal diamond material is fixed to a substrate via a bonding material, the first region can constitute at least a part of the region on the surface of the single crystal diamond material that contacts the bonding material. Furthermore, the first region can constitute the entire surface of the single crystal diamond material. The proportion of the first region to the entire surface of the single crystal diamond material may be, for example, 25% or more, 50% or more, or even 100%.

[0067] <Infrared absorption spectrum> In the single crystal diamond of the single crystal diamond material of embodiment 1, the atomic number N of nitrogen atoms in the C center Ｃ The total number of nitrogen atoms, N ＡＬＬ and the number of nitrogen atoms in the C center, N Ｃ Difference with N ＡＬＬ -N Ｃ The proportion of (N ＡＬＬ -N Ｃ ) / N Ｃ is 1 or more and 10 ５ or less. This makes it easier for nitrogen atoms to aggregate, or nitrogen atoms and vacancies to aggregate, or both, in the single crystal diamond, improving the wear resistance and chipping resistance of the single crystal diamond. As a result, it is possible to provide a single crystal diamond material that combines excellent wear resistance and excellent chipping resistance, and a tool including the same.

[0068] The "C center" is a diamond crystal in which a nitrogen atom replaces a carbon atom on an atomic basis. Diamonds containing the "C center" include type Ib. Single crystal diamonds containing the C center have a wavenumber of 1130 cm in the infrared absorption spectrum measured by Fourier transform infrared spectroscopy. －１ (e.g., wave number 1130±2 cm －１ ) shows the absorption peak.

[0069] <<(N ＡＬＬ -N Ｃ ) / N Ｃ ≫ In single crystal diamond, the number of nitrogen atoms in the C center, N Ｃ The total number of nitrogen atoms, N ＡＬＬ and the number N of nitrogen atoms in the C center Ｃ Difference with N ＡＬＬ -N Ｃ The proportion of (N ＡＬＬ -N Ｃ ) / N Ｃ is 1 or more and 10 ５ This can improve the wear resistance and chipping resistance of the single crystal diamond material. ＡＬＬ -N Ｃ ) / N Ｃ The lower limit of N may be 1.5 or more, or may be 2.0 or more. ＡＬＬ -N Ｃ ) / N Ｃ The upper limit is 2.0 × 10 ４ It may be 19890 or less, or 10 ４ It may be 10 or less, ３ It may be 10 or less, ２ (N ＡＬＬ -N Ｃ ) / N Ｃ is 1.5 or more 10 ４ It may be 2.0 or more and 10 ３ It may be the following:

[0070] In the present disclosure, (N ＡＬＬ -N Ｃ ) / N Ｃ can be determined in the following way:Ｃ is the 1130 cm －１ Based on the integrated intensity of the absorption peak of N, it is calculated using the method described in the literature "I. Kiflawi, A. E. Mayer, P. M. Spear, J. A. van Wyk, G. S. Woods, Philos. Mag. B69 (1994) 1141. and G. S. Woods, J. A. van Wyk, A. T. Collins, Philos. Mag. B62 (1990) 589." ＡＬＬ is determined by performing measurements using secondary ion mass spectrometry (SIMS) under the following conditions. Ｃ and N ＡＬＬ Based on this, (N ＡＬＬ -N Ｃ ) / N Ｃ (Conditions) Measurement device: Product name (product number): "IMS-7f", manufactured by CAMECA Primary ion species: Cesium (Cs+) Primary acceleration voltage: 15 kV Detection area: 30 (μmφ) Measurement accuracy: ±40% (2σ)

[0071] <Method for manufacturing single crystal diamond material> An example of a method for manufacturing the single crystal diamond material of the first embodiment will be described below.

[0072] <First step> In the first step, a diamond single crystal having a nitrogen atom content of 1 ppm to 2000 ppm based on the atomic number is synthesized by a temperature difference method using a solvent metal. The diamond single crystal can be produced by the temperature difference method using, for example, a sample chamber 10 having the configuration shown in Figure 2.

[0073] As shown in Figure 2, in a sample chamber 10 used to produce a diamond single crystal 1, an insulator 2, a carbon source 3, a solvent metal 4, and a seed crystal 5 are arranged in a space surrounded by a graphite heater 7, and a pressure medium 6 is arranged outside the graphite heater 7. The temperature difference method is a method in which a vertical temperature gradient is provided inside the sample chamber 10, and a high temperature section (T ｈｉｇｈ ) carbon source 3, low temperature part (T ｌｏｗIn this synthesis method, a diamond seed crystal 5 is placed in a carbon source 3, a solvent metal 4 is placed between the carbon source 3 and the seed crystal 5, and a diamond single crystal 1 is grown on the seed crystal 5 by maintaining the temperature at which the solvent metal 4 dissolves and at a pressure at which the diamond becomes thermally stable.

[0074] At least one selected from the group consisting of diamond powder, graphite, and pyrolytic carbon can be used as the carbon source 3. At least one metal selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn), or an alloy containing these metals can be used as the solvent metal 4.

[0075] The carbon source 3 or the solvent metal 4 may contain, as a nitrogen source, for example, iron nitride (Fe ２ N, Fe ３ N), aluminum nitride (AlN), phosphorus nitride (P ３ N ４ ), silicon nitride (Si ３ N ４ Nitrides such as nitrite, melamine, and sodium azide can be added singly or as a mixture. Nitrogen-rich diamond or graphite can also be added as a nitrogen source. This allows nitrogen atoms to be contained in the synthesized diamond single crystal. The nitrogen atoms in the diamond single crystal are primarily present as isolated substitutional nitrogen atoms.

[0076] The concentration of the nitrogen source in the carbon source 3 or the solvent metal 4 is adjusted so that the nitrogen atom content in the synthesized diamond single crystal is 1 ppm or more and 2000 ppm or less based on the number of atoms. For example, in the carbon source, the concentration of nitrogen atoms derived from the nitrogen source based on the number of atoms can be 1 ppm or more and 5000 ppm or less. In addition, in the solvent metal, for example, the solvent metal can be an alloy consisting of iron-cobalt-nickel, and the nitrogen source can be Fe ３ In the case of N, the concentration of the nitrogen source can be 0.01% by mass or more and 10% by mass or less.

[0077] The solvent metal 4 may further contain at least one element selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), hafnium (Hf), tantalum (Ta), tungsten (W), osmium (Os), iridium (Ir), and platinum (Pt).

[0078] <Second Step> Next, in the second step, the diamond single crystal obtained in the first step is processed to a thickness of 0.1 mm to 10 mm in the case of a 10 mm square size, for example. Subsequently, the processed diamond single crystal is irradiated with an electron beam to introduce lattice defects into the diamond single crystal and form vacancies.

[0079] The electron beam irradiation conditions were: electron beam energy of 1.0 MeV to 10 MeV, and a dose of 1.0×10 １９ e / m ２ Above 1.0 x 10 ２３ e / m ２ The range of irradiation with the electron beam is larger than the surface (region) of the diamond single crystal that is irradiated with the electron beam. If the energy or dose of the electron beam is less than the above lower limit, the introduction of lattice defects may be insufficient. Conversely, if it exceeds the above upper limit, excessive vacancies may be generated, which may significantly reduce the crystallinity.

[0080] <Third Step> Next, in the third step, the diamond single crystal after the second step is subjected to 10 －３ A pressure of 0.2 Pa to 0.2 MPa and a temperature of 1500°C to 1800°C are applied for 10 to 1000 minutes. The temperature rise rate until the maximum temperature is reached is more than 3°C / min and not more than 6°C / min. The temperature is then lowered at a rate of -0.5°C / min to -5°C / min. After cooling, the cooled diamond single crystal is subjected to an acid treatment. For example, the acid treatment is performed by immersing the diamond single crystal in a mixed solution of concentrated sulfuric acid and concentrated nitric acid for 5 minutes or more. This allows the single crystal diamond material of embodiment 1 to be obtained.

[0081] By carrying out the third step under the above conditions, at least a portion of the surface of the diamond single crystal is transformed into an altered portion, and it is possible to realize the single crystal diamond material of embodiment 1 that comprises a single crystal diamond and an altered portion present on the periphery of the single crystal diamond. This was a new discovery made by the present inventors as a result of extensive research.

[0082] <Features of the manufacturing method for single crystal diamond material of this embodiment> In the manufacturing method for single crystal diamond material of this embodiment, the heating rate in the third step is more than 3°C / min and not more than 6°C / min. As a result, amorphous carbon is formed more prevalently than graphite on the surface of the diamond single crystal. On the surface of the diamond single crystal, there is more amorphous carbon than graphite, and the value of {N1 / (N1+N2)} x 100 tends to be large. In the past, from the perspective of improving production efficiency, a heating rate of 6°C / min or less was not adopted.

[0083] In the manufacturing method of the single crystal diamond material of this embodiment, the diamond single crystal after cooling in the third step is immersed in a mixed solution of concentrated sulfuric acid and concentrated nitric acid for 5 minutes or more. This causes graphite to dissolve preferentially over amorphous carbon in the altered portion. As a result, amorphous carbon becomes more abundant than graphite on the surface of the diamond single crystal, and the value of {N1 / (N1+N2)}×100 tends to become large.

[0084] In the third step, isolated substitutional nitrogen atoms in the diamond single crystal move through the vacancies and aggregate to form aggregated nitrogen atoms.

[0085] In addition, on the entire surface of the single crystal diamond material obtained by the above manufacturing method, the ratio Iπ of the altered portion ＊ / Iσ ＊ It has been confirmed that the percentage of the altered portion is {N1 / (N1+N2)}×100, and that the distribution of the altered portion is almost uniform.

[0086] [Embodiment 2: Tool] A tool according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") is a tool comprising the single crystal diamond material described in Embodiment 1. The single crystal diamond material of Embodiment 1 has an altered portion on its surface, which improves its workability, particularly when laser processing is performed. Therefore, the single crystal diamond material of Embodiment 1 can be easily formed into a shape suitable for the application of the tool by laser processing.

[0087] The tool of embodiment 2 can include a substrate and the single crystal diamond material of embodiment 1 provided on the substrate. In the tool of embodiment 2, the single crystal diamond material is a component involved in machining and is a component that comes into contact with a workpiece during machining.

[0088] The tool according to the second embodiment may be, for example, a cutting tool, a grinding tool, a wear-resistant tool, or a wire-drawing tool.

[0089] Examples of the wire drawing tool include a wire drawing die. Examples of the cutting tool include a drill, an end mill, an indexable cutting tip for a drill, an indexable cutting tip for an end mill, an indexable cutting tip for a milling process, an indexable cutting tip for a turning process, a metal saw, a gear cutting tool, a reamer, a tap, and a cutting tool.

[0090] Examples of the wear-resistant tools include dies, wire guides, scribers, scribing wheels, dressers, bonding tools, surgical knives, etc. Examples of the grinding tools include grinding wheels, etc.

[0091] A wire drawing die 20 will be described as an example of a tool of embodiment 2. Figure 3 is a schematic cross-sectional view of the wire drawing die 20 of embodiment 2. As shown in Figure 3, the wire drawing die 20 comprises a case member 25 having a recess 26, the single crystal diamond material 21 of embodiment 1 provided on a bottom surface 26a of the recess of the case member 25, and a bonding material 24 made of a metal sintered body provided between the case member 25 and the single crystal diamond material 21, with the single crystal diamond material 21 being fixed to the case member 25 by the metal sintered body.

[0092] The case member 25 may be, for example, a cylindrical stainless steel. The metal sintered body that constitutes the joining material 24 is formed by setting the single crystal diamond material 21 in the case member 25, filling the recess 26 with alloy powder, and sintering it. After the single crystal diamond material 21 is fixed to the case member 25, laser processing is performed on the single crystal diamond material 21 to form a through hole in the single crystal diamond material 21. The top of Figure 3 shows the entrance side of the through hole, and the bottom shows the exit side. For laser processing, for example, laser light with a wavelength of 532 nm can be used.

[0093] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0094] [Preparation of Single Crystal Diamond Material] <First Step> Using a sample chamber having the configuration shown in FIG. 2, a single crystal diamond was synthesized by the temperature difference method using a solvent metal.

[0095] An alloy consisting of iron-cobalt-nickel was prepared as a solvent metal, and iron nitride (Fe ３ The concentration of iron nitride in the solvent metal was adjusted so that the nitrogen atom content in the diamond single crystal based on the atomic number was as shown in the "Nitrogen atom content" column in Table 2.

[0096] Diamond powder was used as the carbon source, and approximately 0.5 mg of a diamond single crystal was used as the seed crystal. The temperature in the sample chamber was adjusted using a heater so that there was a temperature difference of several tens of degrees between the high-temperature section where the carbon source was located and the low-temperature section where the seed crystal was located. Using an ultra-high-pressure generator, the pressure was 5.5 GPa, and the temperature in the low-temperature section was controlled to be between 1360°C and 1380°C, and maintained for 100 hours, allowing the synthesis of a diamond single crystal on the seed crystal.

[0097] <Second Step> Next, for samples marked "Yes" in the "Presence or Absence of Second Step" column in Table 1, the resulting diamond single crystal was irradiated with an electron beam. The irradiation conditions were an electron beam energy of 3 MeV and a dose of 3.0 × 10 ２１ e / m ２For samples in Table 1 for which "No" is written in the "Presence or absence of second step" column, the second step was not carried out.

[0098] <Third Step> Next, for samples marked "Yes" in the "Whether or Not Third Step Was Performed" section of Table 1, the diamond single crystal after electron beam irradiation was held at the pressure and temperature listed in the "Pressure" and "Temperature" columns for the time listed in the "Holding Time" column of "Third Step" in Table 1. The heating rate was as listed in the "Heating Rate" column.

[0099] Thereafter, the samples were cooled at the rate shown in the "Cooling Rate" column in Table 1. After cooling, the single crystal diamonds were subjected to an acid treatment. For the acid treatment, the samples were immersed in a mixed solution of concentrated sulfuric acid (concentration 95% by mass) and concentrated nitric acid (concentration 60% by mass) (concentrated sulfuric acid: concentrated nitric acid = 3:1 (volume ratio)) for 30 minutes. This resulted in the production of single crystal diamond material for each sample. The single crystal diamond material for each sample was in the form of a plate, measuring 1 mm ３ For the samples marked "None" in the "Whether or not the third step was performed" column in Table 1, the third step was not performed.

[0100]

[0101] [Evaluation of Single Crystal Diamond Material] <Nitrogen Atom Content> For each sample of single crystal diamond material, the nitrogen atom content (based on the atomic number) of the single crystal diamond was measured by SIMS. The results are shown in the "Nitrogen Atom Content" column in Table 2.

[0102] <Altered portion> It was confirmed whether the single crystal diamond material of each sample comprised a single crystal diamond and an altered portion present on the periphery of the single crystal diamond. The specific confirmation method was as described in embodiment 1. It was confirmed that the single crystal diamond materials of samples 3 to 5 and samples 8 to 10 comprised a single crystal diamond and an altered portion present on the periphery of the single crystal diamond. It was confirmed that the single crystal diamond materials of samples 1, 2, 6 and 7 did not comprise an altered portion.

[0103] The ratio Iπ measured by the above-mentioned method for checking whether or not there is an altered portion ＊ / Iσ ＊, and the percentage {N1 / (N1+N2)}×100 is calculated using "Iπ ＊ / Iσ ＊ " and "{N1 / (N1+N2)}×100" columns.

[0104] Bright field images of Samples 3 to 5 and Samples 8 to 10 confirmed that the surfaces of the single crystal diamond materials contained recesses. For these samples, the maximum thickness of the altered areas present in the recesses was measured. The specific measurement method was as described in Embodiment 1. The results are shown in the "Maximum thickness of the altered area" column of Table 2.

[0105] <Processability> The transmittance of laser light with a wavelength of 532 nm was measured for each sample of single crystal diamond material. The results are shown in the "Transmittance at 532 nm" column in Table 2. The lower the transmittance, the better the laser absorption rate during laser processing, and the more improved the processability of the single crystal diamond material.

[0106] <Arithmetic mean height Sa and maximum height Sz> It was confirmed whether the surface of the single crystal diamond of each sample contained a first region having a maximum height Sz of 60 nm or more. The specific confirmation method is as described in embodiment 1. It was confirmed that the surfaces of the single crystal diamonds of samples 3 to 5 and samples 8 to 10 were entirely composed of the first region. It was confirmed that the surfaces of the single crystal diamonds of samples 1, 2, 6 and 7 did not contain the first region.

[0107] In all samples, the arithmetic mean height Sa and maximum height Sz of the surface showed almost no variation. The arithmetic mean height Sa and maximum height Sz of the entire surface of each sample are shown in the "Arithmetic mean height Sa" and "Maximum height Sz" columns in Table 3. In samples 3 to 5 and samples 8 to 10, these values ​​correspond to the "arithmetic mean height Sa" and "Maximum height Sz" of the first region.

[0108]

[0109]

[0110] [Discussion] The single crystal diamond materials of Samples 3 to 5 and Samples 8 to 10 correspond to Examples. The single crystal diamond materials of Samples 1, 2, 6 and 7 correspond to Comparative Examples. It was confirmed that the single crystal diamond materials of Samples 3 to 5 and Samples 8 to 10 have altered areas on their surfaces that contain a predetermined amount or more of amorphous carbon, which reduces the transmittance of laser light and improves processability during laser processing.

[0111] Although the embodiments and examples of the present disclosure have been described above, it is intended from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments and examples, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0112] REFERENCE SIGNS LIST 1 Diamond single crystal, 2 Insulator, 3 Carbon source, 4 Solvent metal, 5 Seed crystal, 6 Pressure medium, 7 Graphite heater, 10 Sample chamber, 20 Wire drawing die, 21 Single crystal diamond material, 22 Single crystal diamond, 23 Hole, 24 Bonding material, 25 Case member, 26 Recess, 26a Recess bottom, 27 Altered portion.

Claims

1. A single crystal diamond material comprising a single crystal diamond and an altered portion present on the outer periphery of the single crystal diamond, wherein the nitrogen atom content of the single crystal diamond is 1 ppm or more and 2000 ppm or less based on the atomic number, and the single crystal diamond material has an energy loss of π in the range of 285 eV ± 5 eV in a core electron excitation spectrum obtained by electron energy loss spectroscopy using a transmission electron microscope of the altered portion. ＊ Maximum intensity of the peak Iπ ＊ and σ in the range of energy loss 291±5 eV. ＊ Maximum intensity of the peak Iσ ＊ The ratio Iπ ＊ / Iσ ＊ is 0.15 or more, and in the altered portion, the percentage {N1 / (N1+N2)}×100 of the number N1 of primary carbon atoms to the sum N1+N2 of the number N1 of primary carbon atoms constituting amorphous carbon and the number N2 of secondary carbon atoms constituting graphite is 90% or more.

2. A single crystal diamond material according to claim 1, wherein the surface of the single crystal diamond material includes a first region, and the maximum height Sz of the first region as defined in JIS B 0681-2:2018 is 60 nm or more.

3. A single crystal diamond material as described in claim 2, wherein the arithmetic mean height Sa of the first region as defined in JIS B 0681-2:2018 is 3 nm or more.

4. A single crystal diamond material according to any one of claims 1 to 3, wherein the surface of the single crystal diamond material includes recesses, and the maximum thickness of the altered portion present in the recesses is 3 nm or more.

5. A single crystal diamond material according to any one of claims 1 to 4, wherein the coverage of the single crystal diamond by the altered portion is 1% or more.

6. In the single crystal diamond, the number of nitrogen atoms in the C center, N Ｃ The total number of nitrogen atoms, N ＡＬＬ and the number N of nitrogen atoms in the C center Ｃ Difference with N ＡＬＬ -N Ｃ The proportion of (N ＡＬＬ -N Ｃ ) / N Ｃ is 1 or more and 10 ５ 6. A single crystal diamond material according to any one of claims 1 to 5, wherein:

7. A tool comprising a single crystal diamond material according to any one of claims 1 to 6.

8. The tool of claim 7, wherein the tool is a cutting tool, a grinding tool, a wear-resistant tool, or a wire-drawing tool.

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