Composite polycrystals and tools having composite polycrystals

Abstract

A composite polycrystalline material comprising diamond particles and non-diamond-like carbon, wherein the total content of the diamond particles (Vd) and the content of the non-diamond-like carbon (Vg) relative to the composite polycrystalline material is greater than 99% by volume, the median particle size (d50) of the diamond particles is greater than 10 nm and less than 200 nm, and the dislocation density of the diamond particles is 1.0 × 10⁻⁶. 13 m ‑2 Above and 1.0×10 16 m ‑2 The following relationship is satisfied by Equation 1: the content of diamond particles Vd and the content of non-diamond carbon Vg satisfy the following Equation 1: 0.01 < Vg / (Vd+Vg) ≤ 0.5.

Description

Technical Field

[0001] This disclosure relates to composite polycrystals and tools having composite polycrystals. Background Technology

[0002] Polycrystalline diamond has excellent hardness and lacks hardness directionality and cleavage, so it is widely used in cutting tools, dressing tools, die heads, and drilling bits.

[0003] Traditionally, polycrystalline diamond is obtained by sintering diamond powder (as raw material) with sintering aids or binders under thermodynamically stable high pressure and high temperature conditions (generally around 5–8 GPa and 1300–2200 °C). Sintering aids can include iron group metals such as Fe, Co, and Ni, and carbonates such as CaCO3. Binders can include ceramics such as SiC.

[0004] The diamond polycrystals obtained by the above method contain sintering aids or bonding materials. These sintering aids and bonding materials may contribute to a decrease in the hardness, strength, or heat resistance of the diamond polycrystals.

[0005] Diamond polycrystals with sintering aids removed through acid treatment are also known, as well as diamond polycrystals with excellent heat resistance using heat-resistant SiC as a bonding material. However, these diamond polycrystals have low hardness or strength, and their mechanical properties as tool materials are insufficient.

[0006] On the other hand, it is possible to directly transform non-diamond-like carbon materials such as graphite, glassy carbon, amorphous carbon, and onion carbon into diamond under ultra-high pressure and high temperature without the use of sintering aids. Diamond polycrystalline materials are obtained by sintering while directly transforming from a non-diamond phase to a diamond phase (International Publication No. 2005 / 065809 (Patent Document 1), H. Sumiya et al., Japanese Journal of Applied Physics 48(2009)120206 (Non-Patent Document 1)).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2005 / 065809

[0010] Patent Document 2: International Publication No. 2017 / 073293

[0011] Non-patent literature

[0012] Non-patent literature 1: H. Sumiya et al., Japanese Journal of Applied Physics 48(2009)120206 Summary of the Invention

[0013] The composite polycrystalline material disclosed herein is a composite polycrystalline material comprising diamond particles and non-diamond-like carbon, wherein,

[0014] The total content of the diamond particles (Vd) and the content of the non-diamond carbon (Vg) relative to the composite polycrystalline material is greater than 99% by volume.

[0015] The median particle size d50 of the aforementioned diamond particles is greater than 10 nm and less than 200 nm.

[0016] The dislocation density of the aforementioned diamond particles is 1.0 × 10⁻⁶. 13 m -2 Above and 1.0×10 16 m -2 the following,

[0017] The content of diamond particles, Vd, and the content of non-diamond carbon, Vg, satisfy the following relationship (Equation 1).

[0018] 0.01<Vg / (Vd+Vg)≤0.5 Equation 1.

[0019] The tool disclosed herein possesses the aforementioned composite polycrystalline structure. Attached Figure Description

[0020] Figure 1 This is a phase equilibrium diagram for carbon. Detailed Implementation

[0021] [The problem this disclosure aims to solve]

[0022] International Patent Publication No. 2017 / 073293 (Patent Document 2) discloses a composite polycrystal comprising polycrystalline diamond formed by the direct bonding of diamond particles and non-diamond-like carbon dispersed within the polycrystalline diamond, with a hydrogen concentration higher than 1000 ppm and lower than 20000 ppm. Due to its excellent wear resistance, the composite polycrystal of Patent Document 2 is suitable for wear-resistant tools such as wire drawing dies. In recent years, there has been a demand for more efficient wire drawing processes (e.g., high drawing speeds), leading to expectations for further improvements in the performance of composite polycrystals containing diamond particles and non-diamond-like carbon (e.g., improved slip properties, improved hardness, etc.).

[0023] This disclosure was made in view of the above circumstances, and its purpose is to provide a composite polycrystalline material having excellent hardness and excellent lubricity, as well as a tool having the composite polycrystalline material.

[0024] [The Effects of This Disclosure]

[0025] According to this disclosure, a composite polycrystalline material with excellent hardness and excellent lubricity, as well as a tool having the composite polycrystalline material, can be provided.

[0026] [Description of embodiments of this disclosure]

[0027] The embodiments of this disclosure are first described by listing them.

[0028] [1] One aspect of this disclosure relates to a composite polycrystalline material comprising diamond particles and non-diamond-like carbon, wherein,

[0029] The total content of the diamond particles (Vd) and the content of the non-diamond carbon (Vg) relative to the composite polycrystalline material is greater than 99% by volume.

[0030] The median particle size d50 of the aforementioned diamond particles is greater than 10 nm and less than 200 nm.

[0031] The dislocation density of the aforementioned diamond particles is 1.0 × 10⁻⁶. 13 m -2 Above and 1.0×10 16 m -2 the following,

[0032] The content of diamond particles, Vd, and the content of non-diamond carbon, Vg, satisfy the following relationship (Equation 1).

[0033] 0.01<Vg / (Vd+Vg)≤0.5 Equation 1.

[0034] The aforementioned composite polycrystalline material exhibits increased hardness due to the low dislocation density of the diamond particles. In other words, it possesses both excellent hardness and excellent lubricity.

[0035] [2] Preferably, the dislocation density of the diamond particles is 2.0 × 10⁻⁶. 15 Above and 1.0×10 16 m -2 The following is a description of how this specification leads to the formation of a composite polycrystalline material with superior hardness.

[0036] [3] Preferably, the dislocation density of the diamond particles is 2.0 × 10⁻⁶. 15 Above and 7.0×10 15 m -2 The following is a description of how this specification is used to create a composite polycrystalline material with superior hardness.

[0037] [4] Preferably, the median particle size d50 of the diamond particles is 10 nm or more and 100 nm or less. By specifying this, a composite polycrystalline material with superior hardness is formed.

[0038] [5] Preferably, the composite polycrystal further comprises boron, wherein the boron content is 0.01% by mass or more and 1% by mass or less relative to the composite polycrystal. By specifying it in this way, a composite polycrystal with superior sliding properties and superior electrical conductivity is formed.

[0039] [6] Preferably, the content of diamond particles Vd and the content of non-diamond carbon Vg satisfy the following relationship: Equation 2.

[0040] 0.03≤Vg / (Vd+Vg)≤0.4 (Equation 2)

[0041] This specification results in a composite polycrystalline material with superior hardness and lubricity.

[0042] [7] Preferably, in the composite polycrystal of this disclosure, the content of at least one metallic element selected from the group consisting of Group IV, Group V, Group VI elements, iron, aluminum, silicon, cobalt and nickel of the periodic table is less than 1% by volume. By specifying this, a composite polycrystal with superior hardness is formed.

[0043] [8] Preferably, in the composite polycrystal of this disclosure, the content of at least one unavoidable impurity selected from the group consisting of hydrogen, oxygen, nitrogen, alkali metal elements and alkaline earth metal elements is less than 0.1% by volume. By specifying this, a composite polycrystal with superior hardness is formed.

[0044] [9] One aspect of the present disclosure relates to a tool having the above-described composite polycrystalline structure.

[0045] The aforementioned tools possess a composite polycrystalline structure with excellent hardness and slip properties, thus exhibiting superior wear resistance and slip properties in high-speed machining of various materials. Here, "wear resistance" refers to the resistance of the tool to wear during material machining.

[0046] [Details of the embodiments disclosed herein]

[0047] The following describes in detail the embodiments of this disclosure. However, this disclosure is not limited to these examples. Here, in this specification, expressions such as "A to Z" refer to the upper and lower limits of a range (i.e., above A and below Z). When no unit is specified in A, but only in Z, the unit of A is the same as the unit of Z.

[0048] Composite Polycrystalline

[0049] The composite polycrystalline material involved in this embodiment is a composite polycrystalline material containing diamond particles and non-diamond-like carbon, wherein,

[0050] The total content of the diamond particles (Vd) and the content of the non-diamond carbon (Vg) relative to the composite polycrystalline material is greater than 99% by volume.

[0051] The median particle size d50 of the aforementioned diamond particles is greater than 10 nm and less than 200 nm.

[0052] The dislocation density of the aforementioned diamond particles is 1.0 × 10⁻⁶. 13 m -2 Above and 1.0×10 16 m -2 the following,

[0053] The content of diamond particles, Vd, and the content of non-diamond carbon, Vg, satisfy the following relationship (Equation 1).

[0054] 0.01<Vg / (Vd+Vg)≤0.5 Equation 1.

[0055] The aforementioned composite polycrystalline material comprises diamond particles and non-diamond-like carbon. The composite polycrystalline material is based on non-diamond-like carbon and diamond particles, and substantially does not contain a binding phase (binder) formed by one or both of the sintering aid and the binding material. Therefore, the aforementioned composite polycrystalline material possesses very high hardness and strength. Furthermore, even under high-temperature conditions, the aforementioned composite polycrystalline material does not experience deterioration of mechanical properties or degranulation due to differences in thermal expansion coefficients with the binding material or the catalytic effect of the binding material. Additionally, in one aspect of this embodiment, diamond particles can also be understood as diamond grains.

[0056] The aforementioned composite polycrystalline material is a polycrystalline material composed of multiple diamond particles and non-diamond-like carbon. Therefore, this composite polycrystalline material does not have the directionality (anisotropy) and cleavage of single crystals, and has isotropic hardness and wear resistance in all directions.

[0057] In one aspect of this embodiment, the aforementioned composite polycrystalline material can also be understood as consisting of a polycrystalline diamond phase formed by the direct bonding of diamond particles and non-diamond-like carbon dispersed in the polycrystalline diamond phase. Here, "direct bonding of diamond particles" means bonding in a manner in which the diamond particles are in direct contact with each other, for example, meaning that the diamond particles are bonded together without any binder or other different particles.

[0058] The composite polycrystalline material may contain unavoidable impurities within a range that demonstrates the effects of this embodiment. Examples of unavoidable impurities include, for instance, hydrogen, oxygen, nitrogen, alkali metals (lithium (Li), sodium (Na), potassium (K), etc.), and alkaline earth metals (calcium (Ca), magnesium (Mg), etc.). Specifically, in this embodiment, the content of at least one unavoidable impurity selected from the group consisting of hydrogen, oxygen, nitrogen, alkali metals, and alkaline earth metals in the aforementioned composite polycrystalline material is preferably less than 0.1% by volume. The lower limit for the content of the aforementioned unavoidable impurities can, for example, be 0% by volume or more. Furthermore, when the unavoidable impurities include two or more elements, the total content of each element is considered the content of the unavoidable impurities.

[0059] The concentrations of hydrogen, oxygen, nitrogen, etc., in a composite polycrystalline material can be determined using secondary ion mass spectrometry (SIMS). For example, a "CAMECA IMS-7f" (manufactured by AMETEK) can be used in this method, with the primary ion species set to Cs. + Set the primary acceleration voltage to 15.0kV and the detection area to... To determine the concentration of impurities.

[0060] The composite polycrystalline material in this embodiment is a sintered body, but sintered bodies are usually intended to contain a binder, so the term "composite polycrystalline material" is used in this embodiment.

[0061] <Diamond particles and non-diamond carbon>

[0062] (Content of diamond particles Vd, content of non-diamond carbon Vg)

[0063] In this embodiment, the total of the diamond particle content Vd and the non-diamond carbon content Vg is greater than 99% by volume relative to the composite polycrystalline material, preferably greater than 99% by volume and less than 100% by volume.

[0064] The content of diamond particles (Vd, volume%) and the content of non-diamond-like carbon (Vg, volume%) in the composite polycrystalline material can be determined by combining an energy-dispersive X-ray diffraction (EDX) apparatus (e.g., the X-MAX80 EDS system manufactured by OXFORD) with a scanning electron microscope (SEM) (e.g., the JSM-7800F (trade name) manufactured by Nippon Electron Ltd.) (hereinafter also referred to as "SEM-EDX") and X-ray diffraction. The specific measurement method is described below.

[0065] First, the composite polycrystalline material is cut at any point to create a sample containing a cross-section of the composite polycrystalline material. The cross-section can be prepared using a focused ion beam apparatus, a cross-section polishing machine, or similar equipment. Next, the cross-section is observed using a SEM (Self-Electron Microscopy) to obtain a reflected electron image. In the reflected electron image, areas containing diamond particles and non-diamond-like carbon are black areas, while other areas (e.g., elements derived from the binding material) are gray or white areas. The magnification used when observing the cross-section using the SEM is appropriately adjusted so that at least 100 diamond particles are observed in the field of view. For example, the magnification used when observing the cross-section using the SEM can be 10,000x.

[0066] Next, the reflected electron image was binarized using image analysis software (such as "Win ROOF ver. 7.4.5" and "Win ROOF 2018" from Mitani Corporation). This image analysis software automatically sets an appropriate binarization threshold based on the image information (the measurer does not arbitrarily set the threshold). Furthermore, the inventors confirmed that the measurement results did not change significantly even when the image brightness was altered. Based on the binarized image, the area ratio of pixels originating from the dark field (pixels originating from diamond particles and non-diamond carbon) within the measurement field of view was calculated. By treating the calculated area ratio as a volume percentage, the total content of diamond particles and non-diamond carbon (Vd + Vg) (volume %) could be calculated.

[0067] Based on the binarized image, the area ratio of pixels originating from the visible field of view (pixels originating from other regions) in the measured field of view is calculated, thereby allowing the determination of the content (volume %) of other regions.

[0068] The inventors of this invention have confirmed that as long as the total (volume %) of the content of diamond particles and the content of non-diamond carbon in the composite polycrystalline material is measured in the same sample, the measurement results show almost no deviation even if the selected measurement field of view is changed and multiple calculations are performed. That is, the inventors of this invention believe that even if the measurement field of view is arbitrarily set, the results will not change arbitrarily.

[0069] Furthermore, the fact that pixels originating from dark-field regions are derived from diamond particles and non-diamond-like carbon can be confirmed by SEM-EDX-based elemental analysis of the composite polycrystalline material.

[0070] Next, X-ray spectra of the aforementioned cross-section of the composite polycrystalline material were obtained using an X-ray diffraction apparatus (Rigaku Corporation's "MiniFlex600" (trade name)). The conditions of the X-ray diffraction apparatus at this time are as follows.

[0071] Characteristic X-rays: Cu-Kα (wavelength) )

[0072] Tube voltage: 45kV

[0073] Tube current: 40mA

[0074] Filter: Multilayer mirror

[0075] Optical system: lumped method

[0076] X-ray diffraction method: θ-2θ method.

[0077] In the obtained X-ray spectrum, the peak intensities A and B were measured.

[0078] Peak intensity A: The peak intensity of non-diamond-like carbon after removing the background from the peak intensity near the diffraction angle 2θ = 28.5°.

[0079] Peak intensity B: The peak intensity of the diamond particle after removing the background from the peak intensity near the diffraction angle 2θ = 43.9°.

[0080] The diamond particle content Vd (volume %) is obtained by calculating the value of {peak intensity B / (peak intensity A + peak intensity B)} × {the sum of the diamond particle content and the non-diamond carbon content obtained in the above SEM-EDX (Vd + Vg) (volume %)}. Similarly, the non-diamond carbon content Vg (volume %) is obtained by calculating the value of {peak intensity A / (peak intensity A + peak intensity B)} × {the sum of the diamond particle content and the non-diamond carbon content obtained in the above SEM-EDX (Vd + Vg) (volume %)}. Since both non-diamond carbon and diamond particles have the same electron weight, the X-ray peak intensity ratio described above can be considered as the volume ratio in the composite polycrystalline material. Furthermore, no peaks originating from boron were detected in this method. Therefore, even when the composite polycrystalline material contains boron, the sum of the diamond particle content and the non-diamond carbon content is sometimes 100% (volume %).

[0081] In one aspect of this embodiment, the diamond particle content Vd is preferably 50% or more and 98% or less relative to the composite polycrystalline material, and more preferably 60% or more and 95% or less.

[0082] In one aspect of this embodiment, the content of the non-diamond-like carbon, Vg, is preferably 2 vol% or more and 50 vol% or less relative to the composite polycrystalline material, and more preferably 5 vol% or more and 40 vol% or less.

[0083] In one aspect of this embodiment, the content of diamond particles Vd and the content of non-diamond-like carbon Vg satisfy the relationship of Equation 1 below.

[0084] 0.01<Vg / (Vd+Vg)≤0.5 Equation 1.

[0085] In another aspect of this embodiment, the content of diamond particles Vd and the content of non-diamond-like carbon Vg satisfy the relationship of the following formula 2.

[0086] 0.03≤Vg / (Vd+Vg)≤0.4 (Equation 2)

[0087] (Median particle size of diamond particles)

[0088] The median particle size d50 of the diamond particles is 10 nm or more and 200 nm or less, preferably 10 nm or more and 100 nm or less. By making the median particle size d50 of the diamond particles 10 nm or more, a composite polycrystalline material with excellent strength is formed. By making the median particle size d50 of the diamond particles 200 nm or less, a composite polycrystalline material with excellent hardness is formed.

[0089] In this embodiment, the median particle size d50 of the diamond particles refers to the value obtained by measuring the median particle size d50 of multiple diamond particles in each measurement field of view at five arbitrarily selected locations and calculating their average value. The specific method is described below.

[0090] First, the composite polycrystalline material is cut at any point to create a sample containing a cross-section of the composite polycrystalline material. This cross-section can be prepared using a focused ion beam apparatus, a cross-section polishing machine, or similar equipment. Next, the cross-section is observed using a SEM to obtain a reflected electron image. The magnification used for SEM observation of the cross-section is appropriately adjusted to ensure that at least 100 diamond particles are observed in the field of view. For example, a magnification of 10,000x can be used for SEM observation of the cross-section.

[0091] For the five SEM images, with the grain boundaries of the diamond particles observed within the measurement field of view separated, the equivalent circle diameter of each diamond particle was calculated using image processing software (such as Mitani Corporation's "Win ROOF ver. 7.4.5" and "Win ROOF 2018"). Diamond particles appearing outside the measurement field of view were not counted.

[0092] The median particle size d50 in each measurement field is calculated from the distribution of the equivalent circular diameter of each diamond particle, and their average value is calculated. This average value corresponds to the median particle size d50 of the diamond particles.

[0093] Furthermore, the inventors of this invention have confirmed that as long as the median particle size d50 of the diamond particles is calculated in the same sample, the measurement results show almost no deviation even if the selected location of the measurement field of view in the composite polycrystalline material is changed and multiple calculations are performed. That is, the inventors of this invention believe that even if the measurement field of view is arbitrarily set, the results will not change arbitrarily.

[0094] In this embodiment, the diamond particle size d90 is 15 nm or more and 300 nm or less, preferably 15 nm or more and 150 nm or less. By making the diamond particle size d90 15 nm or more, a composite polycrystalline material with excellent strength is formed. By making the diamond particle size d90 150 nm or less, a composite polycrystalline material with excellent hardness is formed.

[0095] In this embodiment, the diamond particle size d90 refers to the value obtained by measuring the particle size d90 of multiple diamond particles in each measurement field of view at five arbitrarily selected locations and calculating their average value. The specific method is the same as the method used to determine the median particle size d50 described above.

[0096] (Dislocation density of diamond particles)

[0097] The dislocation density of the aforementioned diamond particles is 1.0 × 10⁻⁶. 13 m -2 Above and 1.0×10 16 m -2 The preferred value is 2.0 × 10⁻⁶. 15 Above and 1.0×10 16 m -2 Hereinafter, 2.0 × 10 is preferred. 15 Above and 7.0×10 15 m -2 The following is an example of achieving a dislocation density of 1.0 × 10⁻⁶ for diamond particles. 13 m -2 The above results in a composite polycrystalline material with excellent toughness and hardness. This is achieved by setting the dislocation density of the diamond particles to 1.0 × 10⁻⁶. 16 m -2 The following is formed into a composite polycrystalline material with excellent strength.

[0098] Previously, the relationship between the dislocation density of diamond particles in composite polycrystals containing diamond particles and non-diamond-like carbon without a binding phase and the physical properties of such composite polycrystals has not received much attention. Therefore, the inventors of this invention focused on this relationship and conducted an in-depth study on the relationship between the dislocation density of diamond particles in composite polycrystals and the hardness and slip properties of the composite polycrystals. As a result, it was discovered for the first time that, compared to conventional composite polycrystals, reducing the dislocation density of diamond particles increases hardness while maintaining high slip properties. If such a composite polycrystal with excellent hardness and slip properties is used in tools such as wear-resistant tools, it can exhibit excellent slip properties and excellent wear resistance even when performing wire drawing processes using wire drawing dies. Furthermore, this investigation revealed that the dislocation density of diamond particles in conventional composite polycrystals (e.g., the composite polycrystal described in Patent Document 2) is 5 × 10⁻⁶. 16 m -2 Above and 8×10 16 m -2 the following.

[0099] In this specification, the dislocation density of the composite polycrystalline material was measured at a large-scale radiometric facility (e.g., the Kyushu Synchrotron Light Research Center (Saga Prefecture)). Specifically, the measurement was performed using the method described below.

[0100] Prepare a test specimen made of composite polycrystalline material. The specimen has an observation surface of 2 mm × 2 mm and a thickness of 1.0 mm. The observation surface of the specimen is mirror-polished using a diamond polishing slurry with an average particle size of 3 μm.

[0101] For this test specimen, X-ray diffraction measurements were performed under the following conditions to obtain the line profiles of the diffraction peaks from each orientation plane (111), (220), (311), (331), (422), (440), (531), which are the main orientations of diamond.

[0102] (X-ray diffraction measurement conditions)

[0103] X-ray source: radiation light

[0104] Device requirements: Detector: NaI (fluorescence cutoff via appropriate ROI).

[0105] Energy: 18keV (wavelength: )

[0106] Spectroscopic crystal: Si(111)

[0107] Entrance slit: 3mm width × 0.5mm height

[0108] Light-receiving slit: Double slit (3mm width × 0.5mm height)

[0109] Mirror: Platinum coated mirror

[0110] Angle of incidence: 2.5 mrad

[0111] Scanning method: 2θ-θscan

[0112] The measured peaks were the seven peaks of diamond: (111), (220), (311), (331), (422), (440), and (531). However, peaks of this surface index were excluded when it was difficult to obtain the profile due to texture, orientation, etc.

[0113] Measurement conditions: At least 9 measurement points are required within the full width at half maximum (FWHM) corresponding to each measurement peak. The peak intensity must be at least 2000 counts. The lower edge of the peak is also used for analysis; therefore, the measurement range is approximately 10 times the full WHM.

[0114] The line profile obtained by the above X-ray diffraction measurements is a shape that includes both the true extension caused by physical quantities such as the non-uniform strain of the test specimen and the extension caused by the device. To determine the non-uniform strain and crystallite size, the device-induced component is removed from the measured line profile to obtain the true line profile. The true line profile is obtained by fitting the obtained line profile and the device-induced line profile using a pseudo-Voigt function, and then subtracting the device-induced line profile. LaB6 is used as the standard sample for removing the device-induced diffraction line extension. Furthermore, when using highly parallel radiometric light, the device-induced diffraction line extension can also be considered zero.

[0115] The obtained true line profiles are analyzed using the modified Williamson-Hall method and the modified Warren-Averbach method, from which the dislocation density is calculated. The modified Williamson-Hall method and the modified Warren-Averbach method are well-known line profile analysis methods for determining dislocation density.

[0116] The modified Williamson-Hall method is represented by the following equation (I).

[0117] [Number 1]

[0118]

[0119] In equation (I) above, ΔK represents the half-width of the line profile. D represents the crystallite size. M represents the configuration parameter. b represents the Burgers vector. ρ represents the dislocation density. K represents the scattering vector. O(K 2 C) represents K 2 The higher-order term of C. C represents the average value of the contrast factor.

[0120] The C in the above formula (I) is represented by the following formula (II).

[0121] C = C h00 [1-q(h 2 k 2 +h 2 l 2 +k 2 l 2 ) / (h 2 +k 2 +l 2 ) 2 (II)

[0122] In equation (II) above, the contrast factor C for screw dislocations and edge dislocations is... h00 The coefficient q related to the contrast factor is calculated using the ANIZC code, with the slip system as the reference. <110> {111}, Elastic stiffness C 11 1076 GPa, C 12 125 GPa, C 44 The value is calculated to be 576 GPa. In equation (II) above, h, k, and l correspond to the Miller indices (hkl) of diamond, respectively. Contrast factor C h00 The coefficient q is 0.183 for screw dislocations and 0.204 for edge dislocations. The coefficient q related to the contrast factor is 1.35 for screw dislocations and 0.30 for edge dislocations. Furthermore, the ratio of screw dislocations is fixed at 0.5, and the ratio of edge dislocations is fixed at 0.5.

[0123] Furthermore, by using a contrast factor C between dislocations and inhomogeneous strain, the following relationship (III) holds. In the following equation (III), R e The effective radius of the dislocation is represented by ε(L). ε(L) represents the non-uniform strain.

[0124] <ε(L) 2 >=(ρCb 2 / 4π)ln(R e / L) (III)

[0125] Based on the relationship in equation (III) above and the Warren-Averbach formula, the dislocation density ρ and crystallite size can be determined as shown in equation (IV) below, as a modified Warren-Averbach method. In equation (IV) below, A(L) represents the Fourier series. S (L) represents the Fourier series related to the crystallite size. L represents the Fourier length.

[0126] lnA(L)=lnA S(L)-(πL 2 ρb 2 / 2)ln(R e / L)(K 2 C)+O(K 2 C) 2 (IV)

[0127] Detailed descriptions of the modified Williamson-Hall method and the modified Warren-Averbach method are found in "T. Ungar and A. Borbely, 'The effect of dislocation contrast on x-ray linebroadening: A new approach to line profile analysis' Appl. Phys. Lett., vol. 69, no. 21, p. 3173, 1996" and "T. Ungar, S. Ott, P. Sanders, A. Borbely, J. Weertman, 'Dislocations, grain size and planar faults in nanostructured copper determined by high resolution X-ray diffraction and a new procedure of peak profile analysis' Acta Mater., vol. 46, no. 10, pp. 3693-3699, 1998."

[0128] The inventors of this invention have confirmed that, as long as the dislocation density of diamond particles is measured in the same sample, even if the selected measurement range is changed and multiple calculations are performed, the measurement results show almost no deviation. That is, the inventors believe that even if the measurement field of view is arbitrarily set, the results will not change arbitrarily.

[0129] Boron

[0130] In this embodiment, the composite polycrystal further comprises boron, and the boron content relative to the composite polycrystal is preferably 0.01% by mass or more and 1% by mass or less, more preferably 0.05% by mass or more and 0.6% by mass or less. This results in a composite polycrystal possessing superior sliding properties and excellent electrical conductivity. The boron content can be determined using the aforementioned secondary ion mass spectrometry (SIMS) method.

[0131] In one aspect of this embodiment, in the aforementioned composite polycrystalline material, the content of at least one metallic element selected from the group consisting of Group IV, Group V, Group VI elements, iron, aluminum, silicon, cobalt, and nickel of the periodic table is preferably less than 1 volume%, more preferably 0 volume% or more and 0.1 volume% or less. Here, when two or more metallic elements are included, the aforementioned "content of metallic elements" refers to the total content of the two or more metallic elements. The content of the aforementioned metallic elements can be confirmed by performing microstructural observation and elemental analysis on the composite polycrystalline material using EDX with SEM.

[0132] Group 4 elements of the periodic table include, for example, titanium (Ti), zirconium (Zr), and hafnium (Hf). Group 5 elements include, for example, vanadium (V), niobium (Nb), and tantalum (Ta). Group 6 elements include, for example, chromium (Cr), molybdenum (Mo), and tungsten (W).

[0133] Knoop Hardness

[0134] The composite polycrystalline material of this embodiment preferably has a Knoop hardness of 35 GPa or more and 120 GPa or less at room temperature, more preferably 50 GPa or more and 100 GPa or less. The above-mentioned Knoop hardness is determined by a Knoop hardness test performed under the conditions specified in JIS Z2251:2009.

[0135] The Knoop hardness test, as specified in JIS Z 2251:2009, is a well-known method for determining the hardness of industrial materials. The Knoop hardness test determines the hardness of a material by pressing a Knoop indenter against it under a predetermined temperature and a predetermined load (test load). In this embodiment, the predetermined temperature is room temperature (23°C ± 5°C), and the predetermined load is 4.9 N. The Knoop indenter is a diamond indenter with a diamond-shaped, pyramidal base.

[0136] "tool"

[0137] The composite polycrystalline material of this embodiment possesses excellent sliding properties and hardness, making it suitable for use in cutting tools, wear-resistant tools, grinding tools, friction stirring bonding tools, styluses, etc. In other words, the tool of this embodiment incorporates the aforementioned composite polycrystalline material. This tool exhibits excellent wear resistance and excellent sliding properties in wire drawing processes of various materials. When the tool is a wear-resistant tool, it is particularly suitable for wire drawing processes of copper wire, stainless steel wire, etc.

[0138] The aforementioned tools may be made entirely of composite polycrystalline materials, or only a portion thereof (e.g., the part in contact with the wire in the case of wear-resistant tools such as wire drawing dies) may be made of composite polycrystalline materials.

[0139] Cutting tools can include drill bits, end mills, indexable cutting inserts for drill bits, indexable cutting inserts for end mills, indexable cutting inserts for milling, indexable cutting inserts for turning, metalworking saws, gear cutting tools, reamers, taps, and cutting tools.

[0140] As wear-resistant tools, examples include die heads, scribing tools, scribing wheels, and dressing tools.

[0141] Grinding tools can include grinding stones, etc.

[0142] Manufacturing Methods of Composite Polycrystalline Materials

[0143] <Methods for manufacturing composite polycrystalline materials (1)>

[0144] The first manufacturing method of the composite polycrystalline material involved in this embodiment includes:

[0145] The process of preparing non-diamond-like carbon materials as starting materials (first process);

[0146] The process of increasing pressure (second process) involves moving from the graphite stable region to the diamond region while maintaining the starting pressure and starting temperature below 300°C.

[0147] The process of moving the material from the diamond region to the graphite-stabilized region by increasing the temperature, and then maintaining the pressure and temperature in the graphite-stabilized region for a period of 10 minutes to 60 minutes (third process); and

[0148] Further, the pressure and temperature are increased to the sintering pressure and sintering temperature, and the non-diamond carbon material is transformed into diamond particles and sintered at the sintering pressure and sintering temperature (fourth step).

[0149] <First Process: Preparation of Non-Diamond Carbon Materials>

[0150] In this process, a non-diamond carbon material is prepared as the starting material. There are no particular restrictions on the non-diamond carbon material as long as it is carbon. Preferably, the non-diamond carbon material includes low-crystallinity graphite, thermally decomposable graphite, or amorphous carbon. They can be used alone or in combination.

[0151] The purity of the non-diamond carbon material is preferably 99% by volume or more, more preferably 99.5% by volume or more, even more preferably 99.9% by volume or more, and most preferably 100% by volume. In other words, from the viewpoint of suppressing grain growth, the non-diamond carbon material preferably does not contain iron group metals as impurities. Examples of iron group metals include, for example, iron (Fe), cobalt (Co), and nickel (Ni).

[0152] From the viewpoint of suppressing grain growth and promoting the direct transformation to diamond, non-diamond carbon materials are preferably non-diamond carbon materials with low concentrations of impurities such as hydrogen, oxygen, and nitrogen. The concentrations of hydrogen, oxygen, and nitrogen in the non-diamond carbon material are preferably 0.1 vol% or less, more preferably 0.01 vol% or less. Furthermore, the total impurity concentration in the non-diamond carbon material is preferably 0.3 vol% or less, more preferably 0.1 vol% or less.

[0153] The concentration of impurities in non-diamond-like carbon materials can be determined using secondary ion mass spectrometry (SIMS). As an example of this method, a "CAMECA IMS-7f" (manufactured by AMETEK) is used in the apparatus, with the primary ion species set to Cs. + Set the primary acceleration voltage to 15.0kV and the detection area to... To determine the concentration of impurities.

[0154] <Second process: A process of increasing pressure while maintaining a low temperature by moving from the graphite stable region to the diamond region>

[0155] In this process, pressure is increased while maintaining a starting pressure and temperature below 300°C, moving the material from the graphite-stable region to the diamond region. Here, "graphite-stable region" refers to the phase equilibrium region of carbon. Figure 1 The region of graphite in the graphite matrix is ​​thermodynamically stable. Within this stable region, the following relationship holds between pressure P (GPa) and temperature T (°C).

[0156] P <T×0.00286+1.4185

[0157] In this embodiment, "diamond region" refers to the phase equilibrium diagram of carbon. Figure 1 The region of diamond that is thermodynamically stable. The following relationship holds between pressure P (in GPa) and temperature T (in °C) in the diamond region.

[0158] P > T × 0.00286 + 1.4185

[0159] By increasing the pressure from the initial pressure and initial temperature, and moving the pressure from the graphite stable region to the diamond region, the target dislocation density can be formed.

[0160] In this embodiment, the starting temperature is room temperature (23±5℃) and the starting pressure is atmospheric pressure (1013.25hPa).

[0161] In this process, when increasing the pressure from the starting pressure and starting temperature, it is preferable to maintain a temperature below 300°C, and more preferably to maintain a temperature above 0°C and below 300°C. In one aspect of this embodiment, when increasing the pressure from the starting pressure and starting temperature, the temperature can be increased within a range not exceeding 300°C.

[0162] <Third step: Maintaining pressure and temperature within the graphite-stabilized region>

[0163] In this process, after moving from the diamond region to the graphite-stabilized region at increased temperature, the pressure and temperature in the graphite-stabilized region are maintained for a period of 10 to 60 minutes. Moving back from the diamond region to the graphite-stabilized region and maintaining the pressure and temperature there increases the dislocation density.

[0164] The pressure in the graphite stable region is preferably 0 GPa or more and 5 GPa or less, more preferably 0 GPa or more and 3 GPa or less.

[0165] The temperature in the graphite stability region is preferably 0°C or higher and 1500°C or lower, more preferably 0°C or higher and 1000°C or lower.

[0166] In one aspect of this embodiment, preferably, the pressure P in the graphite stable region is 0 GPa or more and 3 GPa or less, the temperature T in the graphite stable region is 25°C or more and 1000°C or less, and the pressure P and the temperature T satisfy the following relationship.

[0167] P <T×0.00286+1.4185

[0168] The time for maintaining pressure and temperature in the graphite-stable region is preferably 10 minutes or more, more preferably 20 minutes or more. From a manufacturing point of view (e.g., the production cycle time), the upper limit of the time for maintaining pressure and temperature in the graphite-stable region is preferably 60 minutes or less.

[0169] <Fourth process: The process of transforming diamond particles and sintering them>

[0170] In this process, the pressure and temperature are further increased to the sintering pressure and sintering temperature. At the aforementioned sintering pressure and sintering temperature, the non-diamond-like carbon material is transformed into diamond particles and then sintered. In one aspect of this embodiment, the heating and pressure increases to the sintering pressure and sintering temperature can be performed simultaneously, or the pressure can be increased to the sintering pressure, followed by the heating to the sintering temperature.

[0171] The sintering pressure is preferably 8 GPa or more and 20 GPa or less, more preferably 10 GPa or more and 16 GPa or less.

[0172] The sintering temperature is preferably above 1800°C and below 2800°C, and more preferably above 1800°C and below 2600°C.

[0173] The sintering pressure and sintering temperature are preferably 1 minute or more and 20 minutes or less, more preferably 5 minutes or more and 20 minutes or less, and even more preferably 10 minutes or more and 20 minutes or less.

[0174] <Methods for manufacturing composite polycrystalline materials (2)>

[0175] The second manufacturing method of the composite polycrystalline material according to this embodiment includes:

[0176] The process of preparing non-diamond-like carbon materials as starting materials (first process);

[0177] The process of increasing pressure and temperature from the initial pressure and temperature by means of the graphite stabilization region (second process);

[0178] The process of maintaining pressure and temperature near the phase boundary for a period of 10 minutes to 60 minutes when increasing pressure across the diamond region (third process); and

[0179] Further, the pressure and temperature are increased to the sintering pressure and sintering temperature, and the non-diamond carbon material is transformed into diamond particles and sintered at the sintering pressure and sintering temperature (fourth step).

[0180] The composite polycrystal obtained by this method tends to have a lower dislocation density compared to the composite polycrystal obtained by the first manufacturing method described above.

[0181] <First Process: Preparation of Non-Diamond Carbon Materials>

[0182] In this process, a non-diamond-like carbon material is prepared as the starting material. The same non-diamond-like carbon material as described in the first manufacturing method above can be used.

[0183] <Second process: The process of increasing pressure and temperature by passing through the graphite stabilization region>

[0184] In this process, the pressure and temperature are increased from the initial pressure and temperature by passing through the graphite stabilization region.

[0185] By increasing the pressure and temperature from the initial pressure and temperature to pass through the graphite stable region, and by maintaining the pressure and temperature near the phase boundary as described later, the dislocation density of the final diamond polycrystalline material is reduced.

[0186] In this embodiment, the starting temperature is room temperature (23±5℃) and the starting pressure is atmospheric pressure (1013.25hPa).

[0187] <Third step: Maintaining pressure and temperature near the phase boundary>

[0188] In this process, when increasing pressure across the diamond region, the pressure and temperature near the phase boundary are maintained for a period of more than 10 minutes and less than 60 minutes.

[0189] The "phase boundary" refers to the boundary between the graphite stable region and the diamond region mentioned above. By maintaining pressure and temperature near the phase boundary, the following effect can be achieved: the dislocation density of the diamond polycrystal decreases, resulting in an increase in the thermal conductivity of the diamond polycrystal.

[0190] The pressure near the aforementioned phase boundary is preferably 1.5 GPa or more and 8 GPa or less, more preferably 2 GPa or more and 7 GPa or less. Here, the following relationship holds between the pressure P (in GPa) and the temperature T (in °C) at the aforementioned phase boundary.

[0191] P = T × 0.00286 + 1.4185

[0192] The temperature near the aforementioned phase boundary is preferably 25°C or higher and 2300°C or lower, more preferably 100°C or higher and 2000°C or lower.

[0193] In one aspect of this embodiment, preferably, the pressure P near the phase boundary is 2 GPa or more and 3 GPa or less, the temperature T near the phase boundary is 300°C or more and 500°C or less, and the pressure P and the temperature T satisfy the above-described relationship.

[0194] The time for maintaining pressure and temperature near the phase boundary is preferably 10 minutes or more, more preferably 20 minutes or more. From a manufacturing point of view (e.g., from the point of view of production cycle time), the upper limit of the time for maintaining pressure and temperature near the phase boundary is preferably 60 minutes or less.

[0195] <Fourth process: The process of transforming diamond particles and sintering them>

[0196] In this process, the pressure and temperature are further increased to the sintering pressure and temperature. Under the aforementioned sintering pressure and temperature, the non-diamond-like carbon material is transformed into diamond particles and then sintered. The specific method can be the same as the first manufacturing method described above.

[0197] In the first and second manufacturing methods of the composite polycrystalline material of this embodiment, the high-pressure, high-temperature generating apparatus is not particularly limited as long as it can provide the pressure and temperature conditions necessary to obtain a thermodynamically stable diamond phase. However, from the viewpoint of improving productivity and workability, a high-pressure, high-temperature generating apparatus or a multi-anvil type high-pressure, high-temperature generating apparatus is preferred. Furthermore, the container holding the non-diamond-like carbon material used as raw material is not particularly limited as long as it is made of a material resistant to high pressure and high temperature; for example, Ta, Nb, etc., are preferred.

[0198] To prevent impurities from contaminating the composite polycrystalline material, for example, non-diamond-like carbon material as raw material is first placed into capsules made of high-melting-point metals such as Ta and Nb, and then heated and sealed in a vacuum to remove adsorbed gases and air from the non-diamond-like carbon material. Afterwards, the second to fourth steps described above are preferably performed.

[0199] In the method for manufacturing composite polycrystalline materials according to this embodiment, the boundary between the graphite stable region and the diamond region is crossed multiple times during the heating and pressurization process from the initial temperature and initial pressure to the sintering temperature and sintering pressure. By performing heating and pressurization in this way, the dislocation density in the manufactured composite polycrystalline material can be controlled.

[0200] Example

[0201] This embodiment will be described in more detail through examples. However, this embodiment is not limited to these examples.

[0202] Fabrication of Composite Polycrystalline Materials

[0203] <First Process: Preparation of Non-Diamond Carbon Materials>

[0204] First, in samples 1 to 14, the following non-diamond-like carbon materials were prepared as raw materials.

[0205] Non-diamond carbon materials

[0206] Samples 1–5, 8–11 and 13: Graphite powder with a particle size of 3 μm

[0207] Samples 6, 7, and 12: Powders containing boron added to graphite powder with a particle size of 3 μm.

[0208] Sample 14: Powder containing iron group elements (Fe, Co, Ni) added to graphite powder with a particle size of 3 μm.

[0209] <Second process: A process that maintains a low temperature while increasing pressure by moving from the graphite stable region to the diamond region, or a process that increases pressure and temperature by passing through the graphite stable region>

[0210] Next, the aforementioned non-diamond-like carbon material was placed in a Ta capsule, heated in a vacuum, and then sealed. Subsequently, using a high-pressure, high-temperature generator, the pressure or temperature was increased from the starting pressure and temperature shown in Table 1 to the arrival pressure and temperature of the first stage shown in Table 1. The starting pressure in Table 1 is marked "0 GPa," but represents atmospheric pressure. The arrival pressure and temperature of the first stage for samples 1-3, 5-7, and 10-14 correspond to the pressure P (unit: GPa) and temperature T (unit: °C) of the diamond region mentioned above, and the following relationship holds.

[0211] P > T × 0.00286 + 1.4185

[0212] On the other hand, the arrival pressure and arrival temperature of the first stage in samples 4, 8 and 9 correspond to the pressure P (unit: GPa) and temperature T (unit: ℃) of the graphite stable region mentioned above, and the following relationship holds.

[0213] P <T×0.00286+1.4185

[0214] <Third step: The process of maintaining pressure and temperature in the graphite stable region, or the process of maintaining pressure and temperature near the phase boundary>

[0215] Starting from the first stage described above, the temperature or pressure is increased to reach the arrival pressure and temperature of the second stage shown in Table 1, and this state is maintained during the holding time of the second stage shown in Table 1. Here, the arrival pressure and temperature of the second stage for samples 1 to 3, 5 to 7, and 10 to 14 correspond to the pressure P (unit: GPa) and temperature T (unit: °C) of the graphite stable region described above. On the other hand, the arrival pressure and temperature of the second stage for samples 4, 8, and 9 correspond to the pressure P (unit: GPa) and temperature T (unit: °C) near the phase boundary described above.

[0216] <Fourth process: The process of transforming diamond particles and sintering them>

[0217] After the third process, the material is heated and pressurized to the fourth stage sintering pressure and temperature according to the arrival pressure and temperature of the third stage shown in Table 1, and then subjected to pressurized heating treatment for the fourth stage sintering time shown in Table 1. This transforms the non-diamond carbon material into diamond particles, which are then sintered. Through the above steps, composite polycrystalline samples 1 to 14 are obtained. Samples 1 to 3, 5 to 7, and 10 to 14 are manufactured using the first manufacturing method described above. Samples 4, 8, and 9 are manufactured using the second manufacturing method described above. Furthermore, for samples 1 to 13, no sintering aid or binder is added to the non-diamond carbon material. Additionally, as sample 15, a commercially available diamond sintered body (manufactured by Sumitomo Electric Industries, Ltd., trade name: WD705F) is prepared. The diamond sintered body consists of diamond particles (particle size 1 μm) (83% by volume) and a metal binder (balance). Samples 1 to 9 correspond to the examples. Samples 10 to 12, 14 and 15 are equivalent to comparative examples. Sample 13 is equivalent to a reference example.

[0218]

[0219] Characteristic Evaluation of Composite Polycrystalline Materials

[0220] For the obtained composite polycrystal, the contents of diamond particles, non-diamond carbon and boron, the contents of metal elements, the contents of unavoidable impurities, the median particle size d50 and particle size d90 of diamond particles, the dislocation density of diamond particles and the resistivity of diamond particles were measured as follows.

[0221] <Content of diamond particles, non-diamond carbon, and boron>

[0222] The content of diamond particles and non-diamond carbon in the composite polycrystalline material was determined by a combination of EDX with SEM and X-ray diffraction. The boron content in the composite polycrystalline material was determined by SIMS. The specific measurement methods were the same as those described in the [Detailed Description of Embodiments of this Disclosure] section above, and therefore will not be repeated. The results are shown in Table 2 (refer to the columns for "Diamond Particle Content", "Non-Diamond Carbon Content", and "Boron Content").

[0223] <Content of metallic elements (content of iron group elements)>

[0224] The content of iron group elements in composite polycrystalline materials and diamond sintered bodies was determined by EDX analysis with attached SEM. Specific measurement conditions are described below. The results are shown in Table 2 (refer to the column "Content of Iron Group Elements Fe, Co, and Ni").

[0225] EDX conditions

[0226] Accelerating voltage 15kV

[0227] <Content of unavoidable impurities>

[0228] The content of unavoidable impurities in the composite polycrystalline material was determined by SIMS. The specific measurement method is the same as that described in the [Details of Embodiments of this Disclosure] section above, and therefore will not be repeated. The results are shown in Table 2 (refer to the "Unavoidable Impurity Content" section).

[0229] <Median particle size d50 and particle size d90 of diamond particles>

[0230] The median particle size d50 and particle size d90 of the diamond particles contained in each composite polycrystalline material were measured. The specific measurement method is the same as that described in the [Detailed Description of Embodiments of this Disclosure] section above, and therefore will not be repeated. The results are shown in Table 3 (refer to the "Median Particle Size d50" and "Particle Size d90" columns).

[0231] <Dislocation density of diamond particles>

[0232] The dislocation density of diamond particles in the composite polycrystalline material was measured. The specific measurement method was the same as that described in the [Detailed Description of Embodiments of this Disclosure] section above, and therefore will not be repeated. The results are shown in Table 3 (refer to the "Dislocation Density" section).

[0233] <Resistivity of diamond particles>

[0234] The resistivity of composite polycrystalline materials was measured using the four-probe method according to JIS standard JIS K 7194. The sample size was set to... The results are shown in Table 3 (refer to the "Resistivity" column). In Table 3, the areas marked with "-" indicate that they could not be measured because the composite polycrystalline material is an insulator.

[0235] Evaluation of Tools with Composite Polycrystalline Structures

[0236] <Wire Drawing Process Test>

[0237] To investigate the wear resistance and sliding properties of the wire drawing die made from the composite polycrystalline material of samples 1 to 14 or the diamond sintered body of sample 15, a wire drawing die was fabricated using the aforementioned composite polycrystalline material or the aforementioned diamond sintered body. Under the following drawing conditions, the drawing process was performed, and the drawing time at the point when the surface roughness Ra of the drawn metal wire became 0.020 μm was calculated. Then, using the drawing time in a drawing die made of single-crystal diamond (manufactured by Sumitomo Electric Industries, Ltd.) as a benchmark, the ratio of the above drawing times (die life ratio) was determined. The results are shown in Table 3.

[0238] (Wire drawing processing conditions)

[0239] Cable: SUS316 cable

[0240] Wire drawing speed: 200m / min

[0241] Table 2

[0242]

[0243] Indicates no measurement was performed.

[0244] Table 3

[0245]

[0246] Die life ratio based on wire drawing dies made of single-crystal diamond

[0247] "result"

[0248] As shown in Table 2, the die life ratios of samples 1 to 9 (Examples) are 2.8 to 6.5, exhibiting excellent sliding properties and wear resistance. On the other hand, the die life ratios of samples 10 to 12, 14, and 15 (Comparative Examples) are 0.1 to 2.5. Sample 13 (Reference Example) has a die life ratio of 3.2, but its holding time in the third process is very long. These results demonstrate that the tools described in the examples exhibit excellent sliding properties and wear resistance.

[0249] The embodiments and examples of this disclosure have been described above, but it is also intended from the outset that the above-described embodiments and examples may be appropriately combined or modified.

[0250] The embodiments and examples disclosed herein should be considered exemplary in all respects, and not restrictive. The scope of the invention is defined not by the foregoing description, but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

Claims

1. A composite polycrystalline material comprising diamond particles and non-diamond-like carbon, wherein, The total content of the diamond particles (Vd) and the content of the non-diamond carbon (Vg) relative to the composite polycrystalline material is greater than 99% by volume. The median particle size d50 of the diamond particles is greater than 10 nm and less than 200 nm. The dislocation density of the diamond particles is 1.0 × 10⁻⁶. 13 m -2 Above and 1.0×10 16 m -2 the following, The content of the non-diamond-like carbon, Vg, is between 5% and 50% by volume relative to the composite polycrystalline material. The content of diamond particles, Vd, and the content of non-diamond carbon, Vg, satisfy the following relationship: Equation 1. 0.01<Vg / (Vd+Vg)≤0.5 Equation 1.

2. The composite polycrystalline material according to claim 1, wherein, The dislocation density of the diamond particles is 2.0 × 10⁻⁶. 15 m -2 Above and 1.0×10 16 m -2 the following.

3. The composite polycrystalline material according to claim 2, wherein, The dislocation density of the diamond particles is 2.0 × 10⁻⁶. 15 m -2 Above and 7.0×10 15 m -2 the following.

4. The composite polycrystalline material according to any one of claims 1 to 3, wherein, The median particle size d50 of the diamond particles is greater than 10 nm and less than 100 nm.

5. The composite polycrystalline material according to any one of claims 1 to 3, wherein, The composite polycrystalline material also contains boron. The boron content is 0.01% by mass or more and 1% by mass or less relative to the composite polycrystalline material.

6. The composite polycrystalline material according to any one of claims 1 to 3, wherein, The content of diamond particles, Vd, and the content of non-diamond carbon, Vg, satisfy the following relationship: Equation 2. 0.03≤Vg / (Vd+Vg)≤0.4 (Equation 2) 7. The composite polycrystalline material according to any one of claims 1 to 3, wherein, The content of at least one metallic element selected from the group consisting of Group 4, Group 5, Group 6 elements, iron, aluminum, silicon, cobalt, and nickel of the periodic table is less than 1 volume.

8. The composite polycrystalline material according to any one of claims 1 to 3, wherein, The content of at least one unavoidable impurity selected from the group consisting of hydrogen, oxygen, nitrogen, alkali metals and alkaline earth metals is less than 0.1% by volume.

9. A tool, wherein, The tool comprises a composite polycrystalline material as described in any one of claims 1 to 8.

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