A diamond sintered body, and a tool having a diamond sintered body

Abstract

A diamond sintered body comprising diamond particles, wherein the content of the diamond particles is 80 volume% or more and 99 volume% or less with respect to the diamond sintered body, the average particle size of the diamond particles is 0.1 μm or more and 50 μm or less, and the dislocation density of the diamond particles is 8.1 × 10¹³ m⁻² or more and less than 1.0 × 10¹⁶ m⁻².

Description

Technology Field

[0001] The present disclosure relates to a diamond sintered body and a tool comprising a diamond sintered body. The present application claims priority based on PCT / JP2020 / 039756, an international application based on the Patent Cooperation Treaty (PCT), filed on October 22, 2020. All contents of the said international application are incorporated herein by reference. Background Technology

[0002] Diamond sintered bodies have excellent hardness and lack directionality of hardness and cleavage, so they are widely used in tools such as cutting bits, dressers and dies, and drilling bits.

[0003] Conventional diamond sintered bodies are obtained by sintering diamond powder, which is the raw material, together with a sintering aid or a binder under high pressure and high temperature conditions where the diamond is thermodynamically stable (generally, a pressure of about 5 to 8 GPa and a temperature of about 1300 to 2200°C). As sintering aids, iron group element metals such as Fe, Co, and Ni, carbonates such as CaCO3, etc. are used. As binders, ceramics such as SiC, etc. are used.

[0004] For example, Japanese Patent Publication No. 2005-239472 (Patent Document 1) describes a high-strength, high-wear-resistant diamond sintered body comprising sintered diamond particles having an average particle size of 2 μm or less and a remainder of a binder phase, wherein the content of the sintered diamond particles in the diamond sintered body is 80 volume% or more and 98 volume% or less, and the binder phase comprises at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, and molybdenum, with a content of 0.5 mass% or more and less than 50 mass%, and cobalt with a content of 50 mass% or more and less than 99.5 mass% in the binder phase, and a part of at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, and molybdenum or A high-strength, high-wear-resistant diamond sintered body is disclosed, characterized in that all of the particles exist as carbide particles with an average particle size of 0.8 μm or less, the structure of the carbide particles is discontinuous, and adjacent diamond particles are bonded to each other.

[0005] In addition, Patent Document 1 discloses a method for manufacturing a high-strength, high-wear-resistant diamond sintered body, characterized by sintering under conditions of a pressure of 5.7 GPa or more and 7.5 GPa or less and a temperature of 1400°C or more and 1900°C or less using a belt-type ultra-high pressure device. Prior art literature

[0006] Patent Document 1: Japanese Patent Publication No. 2005-239472

[0007] The diamond sintered body of the present disclosure is

[0008] As a diamond sintered body containing diamond particles,

[0009] The content of the diamond particles is 80 volume% or more and 99 volume% or less with respect to the diamond sintered body, and

[0010] The average particle size of the above diamond particles is 0.1 μm or more and 50 μm or less, and

[0011] The dislocation density of the above diamond particle is 8.1×10 13 m -2 At least 1.0×10 16 m -2 It is less than.

[0012] The tool of the present disclosure comprises the diamond sintered body. Specific details for implementing the invention

[0013] [Problems to be solved by the present disclosure]

[0014] When the diamond sintered body of Patent Document 1 is applied to cutting tools, etc., defects may occur at the cutting edge. In addition, as cutting processes with higher efficiency (e.g., high feed rates) are required recently, further performance improvements of the diamond sintered body (e.g., suppression of wear caused by cutting processes) are expected.

[0015] The present disclosure is made in consideration of the above circumstances and aims to provide a diamond sintered body having excellent fracture resistance and excellent wear resistance, and a tool having the diamond sintered body.

[0016] [Effects of the present disclosure]

[0017] According to the present disclosure, it is possible to provide a diamond sintered body having excellent fracture resistance and excellent wear resistance, and a tool having the diamond sintered body.

[0018] [Description of embodiments of the present disclosure]

[0019] An embodiment of the present disclosure is described for the first time.

[0020] [1] A diamond sintered body according to one aspect of the present disclosure is,

[0021] As a diamond sintered body containing diamond particles,

[0022] The content of the diamond particles is 80 volume% or more and 99 volume% or less with respect to the diamond sintered body, and

[0023] The average particle size of the above diamond particles is 0.1 μm or more and 50 μm or less, and

[0024] The dislocation density of the above diamond particle is 8.1×10 13 m -2 At least 1.0×10 16 m -2 It is less than.

[0025] The above-mentioned diamond sintered body possesses excellent fracture resistance and excellent wear resistance. Here, "fracture resistance" refers to resistance to tool chipping during material processing. "Wear resistance" refers to resistance to tool wear during material processing.

[0026] [2] The dislocation density of the above diamond particles is 1.0×10 15 m -2 7.0×10 15 m -2 It is desirable that it be less than or equal to this. By defining it in this way, a diamond sintered body with even better fracture resistance and wear resistance is obtained.

[0027] [3] The above diamond sintered body further comprises a binding phase,

[0028] The above combination phase is,

[0029] At least one element selected from the group consisting of a single metal, an alloy, and an intermetallic compound comprising at least one metal element selected from the group consisting of Group 4, Group 5, and Group 6 elements of the periodic table, iron, aluminum, silicon, cobalt, and nickel, or,

[0030] A compound comprising at least one metallic element selected from the group consisting of Group 4, Group 5, and Group 6 elements of the periodic table, iron, aluminum, silicon, cobalt, and nickel, and at least one non-metallic element selected from the group consisting of nitrogen, carbon, boron, and oxygen, and at least one solid solution derived from said compound.

[0031] It is desirable to include [it]. By defining it in this way, a diamond sintered body with even better fracture resistance is obtained.

[0032] [4] The above-mentioned bonding phase preferably contains cobalt. By defining it in this way, a diamond sintered body with even better fracture resistance is obtained.

[0033] [5] A tool according to one embodiment of the present disclosure comprises the diamond sintered body.

[0034] Since the above tool is equipped with the diamond sintered body, it has excellent fracture resistance and excellent wear resistance in the processing of various materials.

[0035] [Details of embodiments of the present disclosure]

[0036] Details of the embodiments of the present disclosure are described below. Furthermore, the present disclosure is not limited to these examples. Herein, the notation in the format "A to Z" in this specification signifies an upper and lower limit of a range (i.e., A or greater and Z or less), and if no unit is specified for A and only a unit is specified for Z, the unit of A and the unit of Z are the same.

[0037] ≪Diamond Sintered Body≫

[0038] The diamond sintered body according to the present embodiment is

[0039] As a diamond sintered body containing diamond particles,

[0040] The content of the diamond particles is 80 volume% or more and 99 volume% or less with respect to the diamond sintered body, and

[0041] The average particle size of the above diamond particles is 0.1 μm or more and 50 μm or less, and

[0042] The dislocation density of the above diamond particle is 8.1×10 13 m -2 At least 1.0×10 16 m -2 It is less than.

[0043] The above-described diamond sintered body comprises diamond particles. That is, the diamond sintered body has diamond as a basic composition. In one aspect of the present embodiment, the diamond particles may be understood as diamond crystal grains. It is preferable that the above-described diamond sintered body further comprises a binding phase (binder) formed by one or both of the sintering aid and the binder. The diamond particles and the binding phase will be described later.

[0044] The above-described diamond sintered body is a polycrystalline body composed of a plurality of diamond particles. Therefore, the above-described diamond sintered body lacks the directional (anisotropy) and cleavage properties of a single crystal, and possesses isotropic hardness and toughness in all directions.

[0045] The diamond sintered body may contain unavoidable impurities within the range that exhibits the effects of the present embodiment. Examples of unavoidable impurities include hydrogen, oxygen, etc.

[0046] Diamond particles

[0047] (Diamond particle content)

[0048] In the present embodiment, the content of the diamond particles is preferably 80 volume% or more and 99 volume% or less with respect to the diamond sintered body, and 80 volume% or more and 90 volume% or less.

[0049] The content of diamond particles (volume %) and the content of the binder phase described below (volume %) in the diamond sintered body can be confirmed by performing microstructure observation, elemental analysis, etc. on the diamond sintered body using an energy dispersive X-ray analyzer (EDX) (Octane Elect EDS system) (hereinafter also referred to as "SEM-EDX") equipped with a scanning electron microscope (SEM) ("JSM-7800F" (product name) manufactured by Nihon Denshi Corporation). The specific measurement method is as follows.

[0050] First, a sample containing a cross-section of the diamond sintered body is prepared by cutting at an arbitrary location on the diamond sintered body. A focused ion beam device, a cross-section polisher device, etc., may be used to prepare the cross-section. Next, the cross-section is observed with a scanning electron microscope (SEM) to obtain a back-field electron image. In the back-field electron image, the region where diamond particles exist becomes a black region, and the region where the bonding phase exists becomes a gray or white region. When observing the cross-section with the SEM, the magnification is appropriately adjusted so that the number of diamond particles observed in the measurement field is 100 or more. For example, if the average particle size of the diamond particles is 0.5 μm, the magnification when observing the cross-section with the SEM may be 10,000 times. If the average particle size of the diamond particles is 30 μm, the magnification when observing the cross-section with the SEM may be 200 times.

[0051] Next, binarization processing is performed on the above-mentioned reflected electronic image using image analysis software (such as “Win ​​ROOF ver. 7.4.5” and “WinROOF 2018” by Shoji Mitani Inc.). The image analysis software automatically sets an appropriate binarization threshold based on image information (the user does not arbitrarily set the threshold). Furthermore, the inventors have confirmed that there is no significant change in the measurement results even when the brightness of the image is varied. From the image after binarization processing, the area ratio of pixels originating from the dark field (pixels originating from diamond particles) occupying the area of ​​the measurement field is calculated. By considering the calculated area ratio as volume %, the diamond particle content (volume %) can be obtained.

[0052] From the image after binarization processing, the area ratio of pixels originating from the bright field (pixels originating from the combination) occupying the area of ​​the measurement field can be calculated, thereby obtaining the content ratio (volume %) of the combination.

[0053] The inventors have confirmed that when measuring the content of diamond particles (volume %) and the content of the binding phase (volume %) described below in a diamond sintered body from the same sample, there is almost no deviation in the measurement results even if the selection point of the measurement field is changed and calculated multiple times. In other words, the inventors believe that even if the measurement field is set arbitrarily, it will not be arbitrary.

[0054] In addition, the fact that pixels originating from the dark field of view originate from diamond particles can be confirmed by performing elemental analysis on the diamond sintered body using SEM-EDX.

[0055] (Average particle size of diamond particles)

[0056] The average particle size of the diamond particles is preferably 0.1 μm or more and 50 μm or less, and 0.2 μm or more and 40 μm or less. Since the average particle size of the diamond particles is 0.1 μm or more, the diamond particles are sintered densely, resulting in a diamond sintered body with excellent fracture resistance. Since the average particle size of the diamond particles is 50 μm or less, there is no anisotropy, and when used as the cutting edge of a cutting tool, the diamond sintered body has excellent cutting stability.

[0057] In this embodiment, the average particle size of the diamond particles refers to a value obtained by measuring the median diameter d50 of a plurality of diamond particles at each of five randomly selected measurement fields and calculating the average value thereof. The specific method is as follows.

[0058] First, a sample containing a cross-section of the diamond sintered body is prepared by cutting at an arbitrary location on the diamond sintered body. A focused ion beam device, a cross-section polisher device, etc., may be used to prepare the cross-section. Next, the cross-section is observed with a scanning electron microscope (SEM) to obtain a back-field electron image. In the back-field electron image, the region where diamond particles exist becomes a black region, and the region where the bonding phase exists becomes a gray or white region. When observing the cross-section with the SEM, the magnification is appropriately adjusted so that the number of diamond particles observed in the measurement field is 100 or more. For example, if the average particle size of the diamond particles is 0.5 μm, the magnification when observing the cross-section with the SEM may be 10,000 times. If the average particle size of the diamond particles is 30 μm, the magnification when observing the cross-section with the SEM may be 200 times.

[0059] For each of the five SEM images, the grain boundaries of the diamond particles observed within the measurement field are separated, and the circle-equivalent diameter of each diamond particle is calculated using image processing software (such as “Win ​​ROOF ver.7.4.5” or “WinROOF2018” by Shoji Mitani Inc.). At this time, diamond particles that are partially outside the measurement field are not counted.

[0060] From the distribution of the circle equivalent diameters of each calculated diamond particle, the median diameter d50 in each measurement field is calculated, and the average value is calculated. The average value corresponds to the average particle size of the diamond particle.

[0061] In addition, the inventors have confirmed that when calculating the average particle size of diamond particles in the same sample, there is almost no deviation in the measurement results even if the selection point of the measurement field of view in the diamond sintered body is changed and calculated multiple times. In other words, the inventors believe that even if the measurement field of view is set arbitrarily, it will not be arbitrary.

[0062] (Dislocation density of diamond particles)

[0063] The dislocation density of the above diamond particle is 8.1×10 13 m -2 At least 1.0×10 16 m -2 Less than and 1.0×10 15 m -2 7.0×10 15 m -2 It is desirable that it be less than or equal to 1.0 × 10⁻⁶. 16 m -2By being less than [value], the occurrence of cracks in diamond particles is suppressed, resulting in a diamond sintered body with excellent fracture resistance. Furthermore, the diamond sintered body has a relatively high thermal conductivity. Therefore, it is possible to suppress thermal wear caused by the temperature rise of the cutting edge during machining. In addition, the dislocation density of the diamond particles is 8.1 × 10⁻⁶ 13 m -2 The inventors have confirmed that diamond sintered bodies of less than [amount] cannot be manufactured.

[0064] Conventionally, no attention has been paid to the correlation between the dislocation density of diamond particles in a diamond sintered body and the physical properties of said diamond sintered body. Therefore, the inventors of the present invention conducted a thorough investigation into the relationship between the dislocation density of diamond particles in a diamond sintered body and the fracture resistance and wear resistance of said diamond sintered body. As a result, it was discovered for the first time that lowering the dislocation density of diamond particles compared to conventional diamond sintered bodies suppresses the occurrence of cracks caused by the sliding movement of dislocations in diamond particles, thereby improving fracture resistance. Furthermore, it was discovered for the first time that lowering the dislocation density of diamond particles can suppress wear during machining. It is believed that this is because reducing the dislocation density allows the heat generated during machining to be effectively transferred to the entire diamond sintered body, thereby suppressing wear of the diamond sintered body caused by heat generation. Additionally, through this investigation, it was found that a conventional diamond sintered body (e.g., the diamond sintered body described in Patent Document 1) has a dislocation density of diamond particles of 1.01 × 10⁻⁶ 16 m -2 1.18×10 16 m -2 It is becoming clear that it is less than

[0065] In this specification, the dislocation density of a diamond sintered body is measured at a large synchrotron radiation facility (e.g., Kyushu Synchrotron Radiation Research Center (Saga Prefecture)). Specifically, it is measured by the following method.

[0066] A test specimen containing a diamond sintered body is prepared. The size of the test specimen is such that the observation surface is 3 mm × 6 mm and the thickness is 0.4 mm. The observation surface of the test specimen is mirror-polished using a diamond slurry with an average particle size of 3 μm, and then immersed in hydrochloric acid for 72 hours. As a result, the binder phase on the observation surface of the test specimen is dissolved in hydrochloric acid, and diamond particles remain.

[0067] For the above test specimen, X-ray diffraction measurements are performed under the following conditions to obtain line profiles of diffraction peaks from each orientation plane of the major orientations of diamond (111), (220), (311), (331), (422), (440), (531).

[0068] (X-ray diffraction measurement conditions)

[0069] X-ray source: Synchrotron radiation

[0070] Device conditions: Detector NaI (cuts fluorescence by an appropriate ROI.)

[0071] Energy: 18 keV (Wavelength: 0.6888 Å)

[0072] Spectroscopic crystal: Si(111)

[0073] Incident slit: Width 3 mm × Height 0.5 mm

[0074] Light receiving slit: Double slit (width 3 mm × height 0.5 mm)

[0075] Mirror: Platinum-coated mirror

[0076] Angle of incidence: 2.5 mrad

[0077] Injection method: 2θ-θ scan

[0078] Measurement peaks: 7 peaks of diamond (111), (220), (311), (331), (422), (440), (531). However, if it is difficult to obtain a profile due to texture, orientation, etc., the peaks of the face indices are excluded.

[0079] Measurement conditions: Ensure that there are at least 9 measurement points within the full width at half maximum corresponding to each measurement peak. The peak top intensity should be at least 2,000 counts. Since the tail of the peak is also used for analysis, the measurement range should be approximately 10 times the full width at half maximum.

[0080] The line profile obtained by the above-described X-ray diffraction measurement has a shape that includes both true enlargement caused by physical quantities such as non-uniform deformation of the test specimen and enlargement caused by the device. To determine non-uniform deformation and crystallite size, the device-caused 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-caused line profile using a pseudo-Voigt function and subtracting the device-caused line profile. LaB6 is used as a standard sample to remove the device-caused diffraction line enlargement. Additionally, when using synchrotron radiation with high parallelism, the device-caused diffraction line enlargement may be considered as zero.

[0081] The dislocation density is calculated by analyzing the obtained true line profile using the modified Williamson-Hall method and the modified Warren-Averbach method. The modified Williamson-Hall method and the modified Warren-Averbach method are known line profile analysis methods used to determine dislocation density.

[0082] The modified Williamson-Hall method is represented by the following equation (I).

[0083]

[0084] In the above equation (I), ΔK represents the full width at half maximum of the line profile. D represents the crystallite size. M represents the batch parameter. b represents the Burgers vector. ρ represents the dislocation density. K represents the scattering vector. O(K 2 C) is K 2 Represents the higher-order term of C. C represents the average value of the contrast factor.

[0085] C in the above equation (I) is represented by the following equation (II).

[0086] 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)

[0087] In the above equation (II), the contrast factor C at the spiral dislocation and the edge dislocation, respectively. h00 The coefficient q regarding the and contrast factor is, using the calculation code ANIZC, the slip system <110> {111}, elastic stiffness C 11 This 1076 GPa, C 12 Ga 125 GPa, C 44 It is calculated by setting α to 576 GPa. In the above Equation (II), h, k, and l correspond to the diamond mirror index (hkl), respectively. Contrast factor C h00 The spiral potential is 0.183 and the blade potential is 0.204. The coefficient q for the contrast factor is the spiral potential 1.35 and the blade potential 0.30. Also, the spiral potential ratio and the blade potential ratio are fixed at 0.5.

[0088] In addition, the relationship given by Equation (III) below holds between the dislocation and the non-uniform deformation using the contrast factor C. In Equation (III) below, Re represents the effective radius of the dislocation. ε(L) represents the non-uniform strain.

[0089] <ε(L) 2 >=(ρCb 2 / 4π)ln(R e / L) (Ⅲ)

[0090] From the relationship in Equation (III) above and the Warren-Averbach equation, it can be expressed as Equation (IV) below, and the dislocation density ρ and determinant size can be obtained using the modified Warren-Averbach method. In Equation (IV) below, A(L) represents the Fourier series. A S (L) represents the Fourier series with respect to the determinant size. L represents the Fourier length.

[0091] lnA(L)=lnA S (L)-(πL 2 ρb 2 / 2)ln(R e / L)(K 2 C)+O(K 2 C) 2 (IV)

[0092] Details of the modified Williamson-Hall method and the modified Warren-Averbach method are described in "T. Ungar and A. Borbely, "The effect of dislocation contrast on x-ray line broadening: 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."

[0093] The inventors have confirmed that when measuring the dislocation density of diamond particles in the same sample, there is almost no deviation in the measurement results even if the selection point of the measurement range is changed and calculated multiple times. In other words, the inventors believe that even if the measurement field of view is set arbitrarily, it will not be arbitrary.

[0094] <Combination>

[0095] In the present embodiment, the diamond sintered body further comprises a binding phase, and

[0096] The above combination phase is,

[0097] At least one selected from the group consisting of a single metal, an alloy, and an intermetallic compound comprising at least one metal element selected from the group consisting of Group 4, Group 5, Group 6 elements of the periodic table, iron, aluminum, silicon, cobalt, and nickel (hereinafter also referred to as "Group A"), or,

[0098] A compound comprising at least one metallic element selected from the group consisting of Group 4, Group 5, and Group 6 elements of the periodic table, iron, aluminum, silicon, cobalt, and nickel (Group A), and at least one non-metallic element selected from the group consisting of nitrogen, carbon, boron, and oxygen (hereinafter also referred to as "Group B"), and at least one solid solution derived from said compound.

[0099] It is desirable to include. In other words, the above combination may be in any one of the following forms (a) to (f).

[0100] (a) The above-mentioned binding phase is composed of at least one selected from the group consisting of a single metal, an alloy, and an intermetallic compound comprising at least one metal element selected from group A.

[0101] (b) The above-mentioned binding phase comprises at least one selected from the group consisting of a single metal, an alloy, and an intermetallic compound comprising at least one metal element selected from group A.

[0102] (c) The above-mentioned binding phase is composed of at least one selected from the group consisting of a compound comprising at least one metal element selected from group A and at least one non-metal element selected from group B, and a solid solution derived from said compound.

[0103] (d) The above-mentioned binding phase comprises at least one selected from the group consisting of a compound comprising at least one metal element selected from group A and at least one non-metal element selected from group B, and a solid solution derived from said compound.

[0104] (e) The above-mentioned bonding phase is composed of at least one selected from the group consisting of a single metal, an alloy, and an intermetallic compound comprising at least one metal element selected from group A, a compound comprising at least one metal element selected from group A and at least one nonmetal element selected from group B, and at least one selected from the group consisting of a solid solution derived from said compound.

[0105] (f) The above-mentioned bonding phase comprises at least one selected from the group consisting of a single metal, an alloy, and an intermetallic compound comprising at least one metal element selected from group A, and at least one selected from the group consisting of a compound comprising at least one metal element selected from group A and at least one nonmetal element selected from group B, and a solid solution derived from said compound.

[0106] 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).

[0107] In one aspect of the present embodiment, the binding phase preferably comprises at least one selected from the group consisting of cobalt, titanium, iron, tungsten, and boron, and more preferably comprises cobalt.

[0108] The composition of the bonding phase included in the diamond sintered body can be determined by the EDX of the aforementioned SEM unit.

[0109] (Content of the binding phase)

[0110] The content of the above-mentioned binder is preferably 1 volume% or more and 20 volume% or less with respect to the diamond sintered body, and more preferably 10 volume% or more and 20 volume% or less. The content of the binder (volume%) can be confirmed by performing microstructure observation, elemental analysis, etc. on the diamond sintered body using the EDX of the aforementioned SEM unit.

[0111] Tools

[0112] Since the diamond sintered body of the present embodiment has excellent fracture resistance and wear resistance, it can be suitably used for cutting tools, wear-resistant tools, grinding tools, friction stir joining tools, etc. That is, the tool of the present embodiment is equipped with the diamond sintered body described above. The tool has excellent fracture resistance and excellent wear resistance in the processing of various materials. When the tool is a cutting tool, the cutting tool is particularly suitable for turning and turning operations on aluminum alloys (e.g., A390, AC4C), etc.

[0113] The above-mentioned tool may be composed entirely of a sintered diamond body, or only a part thereof (e.g., in the case of a cutting tool, the cutting edge) may be composed of a sintered diamond body.

[0114] Examples of cutting tools include drills, end mills, interchangeable cutting tips for drills, interchangeable cutting tips for end mills, interchangeable cutting tips for framing, interchangeable cutting tips for turning, metal saws, gear cutting tools, reamers, taps, cutting bits, etc.

[0115] Examples of wear-resistant tools include dies, scribers, scribing wheels, and dressers.

[0116] Examples of grinding tools include grinding wheels.

[0117] Method for Manufacturing a Sintered Diamond Body

[0118] The method for manufacturing a diamond sintered body according to the present embodiment is

[0119] A process for preparing raw material powder of diamond particles and raw material powder of a binder phase, and

[0120] A process of obtaining a mixed powder by mixing the raw material powder of the above-mentioned diamond particles and the raw material powder of the above-mentioned binding phase, and

[0121] A process of sintering the mixed powder at a sintering pressure of 4 GPa or more and less than 5 GPa, a sintering temperature of 1400℃ or more and 1550℃ or less, for a sintering time of 15 minutes or more and 60 minutes or less, and

[0122] A process of reducing the potential in the diamond particles by heating the mixed powder at a holding pressure of 6.5 GPa or more and 8 GPa or less, a holding temperature of 1600°C or more and 1900°C or less, and a holding time of 50 minutes or more and 190 minutes or less.

[0123] Equipped with

[0124] Process of preparing raw material powder of diamond particles and raw material powder of the binder phase

[0125] In this process, a raw material powder of diamond particles (hereinafter also referred to as "diamond powder") and a raw material powder of a binder (hereinafter also referred to as "binder powder") are prepared. The diamond powder is not particularly limited, and known diamond particles may be used as the raw material powder.

[0126] The average particle size of the diamond powder is not particularly limited and, for example, can be 0.1 μm or more and 50 μm or less.

[0127] The binder raw material powder is not particularly limited and can be any powder containing an element that constitutes the binder. Examples of binder raw material powders include cobalt powder, titanium powder, etc. Depending on the composition of the binder to be desired, one type of powder may be used alone, or multiple types of powders may be used in combination.

[0128] Process of obtaining mixed powder

[0129] In this process, the raw material powder of the diamond particles (diamond powder) and the raw material powder of the binder phase (binder phase raw material powder) are mixed to obtain a mixed powder. At this time, the diamond powder and the binder phase raw material powder may be mixed at any mixing ratio so that the content of diamond particles in the diamond sintered body is within the aforementioned range.

[0130] The method of mixing the two powders is not particularly limited and may be a mixing method using an atritor or a mixing method using a ball mill. The mixing method may be wet or dry.

[0131] <Process of sintering mixed powder>

[0132] In this process, the mixed powder is sintered at a sintering pressure of 4 GPa or more and less than 5 GPa, a sintering temperature of 1400°C or more and 1550°C or less, and for a sintering time of 15 minutes or more and 60 minutes or less.

[0133] In this embodiment, the path from the state of room temperature (23±5℃) and atmospheric pressure to the state of sintering pressure and sintering temperature is not particularly limited.

[0134] In the method for manufacturing a diamond sintered body according to the present embodiment, the high-pressure, high-temperature generating device used is not particularly limited as long as it is a device capable of achieving the desired pressure and temperature conditions. From the perspective of increasing productivity and workability, a belt-type high-pressure, high-temperature generating device is preferred. Furthermore, the container for holding the mixed powder is not particularly limited as long as it is made of a material with high pressure and high temperature resistance; for example, tantalum (Ta) and niobium (Nb) are suitably used.

[0135] To prevent the incorporation of impurities into the diamond sintered body, for example, the above-mentioned mixed powder is first placed in a capsule made of a high-melting-point metal such as Ta or Nb, heated in a vacuum, and sealed to remove adsorbed gas and air from the mixed powder. Subsequently, it is preferable to perform a process of sintering the above-mentioned mixed powder and a process of reducing dislocations in the diamond particles described later. In one aspect of the present embodiment, after the process of sintering the above-mentioned mixed powder, it is preferable to perform a process of reducing dislocations in the diamond particles continuously in the same state without removing the mixed powder from the capsule made of the high-melting-point metal.

[0136] The above sintering pressure is preferably 4 GPa or more and less than 5 GPa, and more preferably 4.5 GPa or more and less than 5 GPa.

[0137] The above sintering temperature is preferably 1400℃ or higher and 1550℃ or lower, and more preferably 1450℃ or higher and 1550℃ or lower.

[0138] The above sintering time is preferably 15 minutes or more and 60 minutes or less, and more preferably 15 minutes or more and 20 minutes or less.

[0139] Process for reducing dislocations in diamond particles

[0140] In this process, the mixed powder is heated for a holding time of 50 minutes to 190 minutes at a holding pressure of 6.5 GPa or more and 8 GPa or less, and a holding temperature of 1600°C or more and 1900°C or less, thereby reducing the dislocations in the diamond particles. By doing so, the diamond sintered body of the present disclosure is obtained. The inventors believe that the dissolution and reprecipitation reactions of diamond are promoted by this process, but since the reprecipitated diamond particles have low dislocations, a diamond sintered body with low dislocations is obtained.

[0141] The above-mentioned holding pressure is preferably 6.5 GPa or more and 8 GPa or less, and more preferably 6.5 GPa or more and 7 GPa or less.

[0142] The above holding temperature is preferably 1600℃ or higher and 1900℃ or lower, and more preferably 1600℃ or higher and 1700℃ or lower.

[0143] The above retention time is preferably 50 minutes or more and 190 minutes or less, and more preferably 60 minutes or more and 180 minutes or less.

[0144] Examples

[0145] The present embodiment will be explained in more detail by way of examples. However, the present embodiment is not limited by these examples.

[0146] ≪Production of Sintered Diamond Bodies≫

[0147] Process of preparing raw material powder of diamond particles and raw material powder of the binder phase

[0148] As raw material powders, powders with the average particle size or composition shown in Table 1-1 and Table 1-2 were prepared.

[0149] [Table 1-1]

[0150]

[0151] [Table 1-2]

[0152]

[0153] Process of obtaining mixed powder

[0154] In order for the final diamond sintered body to have the composition described in Table 3-1 or Table 3-2, each prepared raw material powder was added in various mixing ratios and dry-mixed using a ball mill to produce a mixed powder. Here, the mixed powder is sintered while in contact with a disc made of WC-6% Co cemented carbide alloy, as described below. Therefore, it is believed that during sintering, cobalt and tungsten from the disc infiltrate into the diamond sintered body, thereby increasing the cobalt and tungsten content in the diamond sintered body. The mixing ratio of each raw material powder was determined by taking into account in advance the increase in the cobalt and tungsten content.

[0155] <Process of sintering mixed powder>

[0156] Next, the above mixed powder was placed in a capsule made of Ta while in contact with a disc made of WC-6% Co cemented carbide alloy, heated in a vacuum, and sealed. Then, the above mixed powder was sintered using a high-pressure high-temperature generator at the sintering pressure, sintering temperature, and sintering time shown in Table 2-1 or Table 2-2.

[0157] Process for reducing dislocations in diamond particles

[0158] Following the process of sintering the aforementioned mixed powder, the mixed powder was heat-treated at the holding pressure, holding temperature, and holding time shown in Table 2-1 or Table 2-2. In addition, this process was not performed for Sample 8 and Sample 28. Through the above process, diamond sintered bodies of Samples 1 to 32 were manufactured.

[0159] [Table 2-1]

[0160]

[0161] [Table 2-2]

[0162]

[0163] ≪Evaluation of Characteristics of Diamond Sintered Bodies≫

[0164] <Composition of Diamond Sintered Body>

[0165] The content ratio (volume ratio) of diamond particles and the binding phase in the diamond sintered body was measured. Since the specific measurement method is the same as the method described in the column [Details of the Embodiments of the Present Disclosure] above, the description thereof is not repeated. For each sample, it was confirmed that the content ratio of diamond particles in the diamond sintered body was as shown in Table 3-1 and Table 3-2 (see column "Content Ratio").

[0166] Average particle size of diamond particles

[0167] The average particle size of diamond particles in a diamond sintered body was measured. Since the specific measurement method is the same as the method described in the column [Details of the Embodiment of the Present Disclosure] above, the description thereof is not repeated. The results are shown in Table 3-1 and Table 3-2 (refer to the column "Average Particle Size").

[0168] <Composition of the bonding phase>

[0169] The composition of the binder phase in the diamond sintered body was determined by SEM-EDX. Since the specific measurement method is the same as the method described in the column [Details of the Embodiments of the Present Disclosure] above, the description thereof is not repeated. The results are shown in Tables 3-1 and 3-2 (refer to the column "Composition of the binder phase").

[0170] Dislocation density of diamond particles

[0171] The dislocation density of diamond particles in a diamond sintered body was measured. Since the specific measurement method is the same as the method described in the column [Details of the Embodiments of the Present Disclosure] above, the description is not repeated. The results are shown in Table 3-1 and Table 3-2 (refer to the column "Dislocation Density").

[0172] ≪Evaluation of a Tool Equipped with a Diamond Sintered Body≫

[0173] <Cutting Test 1: Turning Test>

[0174] A cutting tool (holder: CSRP R3225-N12, tip: SPGN120304, a tool equipped with the diamond sintered body at the cutting edge of the tip) was manufactured using each of the diamond sintered bodies of samples 1 to 14 produced as described above, and a turning test was performed. The cutting conditions for the turning test are shown below. The above turning test can be evaluated as a cutting tool with excellent fracture resistance and wear resistance as the cutting distance (km) increases. The results are shown in Table 3-1. In cutting test 1, samples 1 to 7, sample 10, and samples 12 to 14 correspond to examples. Samples 8, sample 9, and sample 11 correspond to comparative examples.

[0175] (Cutting conditions for turning test)

[0176] Workpiece: A390 (φ120 mm × 280 mm)

[0177] Cutting speed: 800 m / min

[0178] Feed rate: 0.12 mm / rev

[0179] Cut depth: 0.5 mm

[0180] Coolant: wet

[0181] Evaluation Method: Turn the outer diameter of the workpiece and measure the cutting distance (km) until the average clearance wear width of the cutting tool reaches 250 μm.

[0182] <Cutting Test 2: Turning Test>

[0183] Using each of the diamond sintered bodies of samples 15 to 20 produced as described above, a cutting tool (holder: CSRP R3225-N12, tip: SPGN120308, a tool equipped with the diamond sintered body at the cutting edge of the tip) was manufactured, and a turning test was performed. The cutting conditions for the turning test are shown below. The above turning test can be evaluated as a cutting tool with excellent fracture resistance and wear resistance as the cutting distance (km) increases.

[0184] The results are shown in Table 3-1. In cutting test 2, samples 15 to 19 correspond to examples. Sample 20 corresponds to a comparative example.

[0185] (Cutting conditions for turning test)

[0186] Workpiece: Ti-6Al-4V (φ120 mm × 280 mm)

[0187] Cutting speed: 250 m / min

[0188] Feed rate: 0.1 mm / rev

[0189] Cut depth: 0.4 mm

[0190] Coolant: wet

[0191] Evaluation Method: Turn the outer diameter of the workpiece and measure the cutting distance (km) until the average clearance wear width of the cutting tool reaches 200 μm.

[0192] [Table 3-1]

[0193]

[0194] <Result>

[0195] From the results of cutting test 1, the cutting tools of samples 1 to 7, sample 10, and samples 12 to 14 (cutting tools of the example) obtained good results with a cutting distance of 10.1 km or more. On the other hand, the cutting tools of samples 8, sample 9, and sample 11 (cutting tools of the comparative example) showed imperfections in the initial stage of the cutting process, so the cutting distance could not be determined. From the above results, it was found that the cutting tools of the example had superior fracture resistance and wear resistance compared to the cutting tools of the comparative example.

[0196] From the results of cutting test 2, the cutting tools of samples 15 to 19 (cutting tools of the example) obtained good results, with a cutting distance of 3.5 km or more. On the other hand, the cutting tool of sample 20 (cutting tool of the comparative example) showed imperfections in the initial stage of the cutting process, so the cutting distance could not be determined. From the above results, it was found that the cutting tools of the example had superior fracture resistance and wear resistance compared to the cutting tools of the comparative example.

[0197] <Cutting Test 3: Turning Test>

[0198] Using each of the diamond sintered bodies of samples 21 to 32 produced as described above, a cutting tool (holder: CSRP R3225-N12, tip: SPGN120304, a tool equipped with the diamond sintered body at the cutting edge of the tip) was manufactured, and a turning test was performed. The cutting conditions for the turning test are shown below. The above turning test can be evaluated as a cutting tool with excellent fracture resistance and wear resistance as the cutting distance (km) increases. The results are shown in Table 3-2. In cutting test 3, samples 21 to 27, sample 30, and sample 32 correspond to examples. Samples 28, sample 29, and sample 31 correspond to comparative examples.

[0199] (Cutting conditions for turning test)

[0200] Workpiece: AC4C (φ120 mm × 280 mm)

[0201] Cutting speed: 1200 m / min

[0202] Feed rate: 0.2 mm / rev

[0203] Cut: 1.2 mm

[0204] Coolant: wet

[0205] Evaluation Method: Turn the outer diameter of the workpiece and measure the cutting distance (km) until the average clearance wear width of the cutting tool reaches 250 μm.

[0206] [Table 3-2]

[0207]

[0208] <Result>

[0209] From the results of cutting test 3, the cutting tools of samples 21–27, sample 30, and sample 32 (cutting tools of the example) obtained good results with a cutting distance of 12.2 km or more. On the other hand, the cutting tools of samples 28, sample 29, and sample 31 (cutting tools of the comparative example) showed imperfections in the initial stage of the cutting process, so the cutting distance could not be determined. From the above results, it was found that the cutting tools of the example had superior fracture resistance and wear resistance compared to the cutting tools of the comparative example.

[0210] Although the embodiments and examples of the present disclosure have been described above, it is also intended from the outset to appropriately combine or modify the configurations of each of the aforementioned embodiments and examples in various ways.

[0211] The embodiments and examples disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the invention is defined by the claims, not by the description above, and is intended to include all modifications within the meaning and scope of the claims and equivalents.

Claims

Claim 1 A diamond sintered body comprising diamond particles, wherein the sintered phase comprises a binding phase, the binding phase comprises tungsten and cobalt, the content of the diamond particles is 80 volume% or more and 99 volume% or less with respect to the diamond sintered body, the average particle size of the diamond particles is 0.1 μm or more and 50 μm or less, and the dislocation density of the diamond particles is 8.1 × 10⁻⁶ 13 m -2 At least 1.0×10 16 m -2 A diamond sintered body that is less than Claim 2 In claim 1, the dislocation density of the diamond particle is 1.0 × 10⁻⁶ 15 m -2 7.0×10 15 m -2 A diamond sintered body that is as follows. Claim 3 A diamond sintered body according to claim 1 or 2, wherein the binding phase comprises at least one selected from the group consisting of a single metal, an alloy, and an intermetallic compound comprising at least one metal element selected from the group consisting of a group 4 element, a group 5 element, a group 6 element excluding tungsten, iron, aluminum, silicon, and nickel of the periodic table, or at least one compound comprising at least one non-metal element selected from the group consisting of a group 4 element, a group 5 element, a group 6 element excluding tungsten, iron, aluminum, silicon, and nickel, and at least one non-metal element selected from the group consisting of nitrogen, carbon, boron, and oxygen, and a solid solution derived from said compound. Claim 4 A tool having a diamond sintered body as described in paragraph 1 or 2. Claim 5 delete

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