Cubic boron nitride sintered body and method for manufacturing the same, and tool

Abstract

A cubic boron nitride sintered body, a method for manufacturing the same, and tools are provided. The cubic boron nitride sintered body comprises cubic boron nitride and a binding phase, wherein the binding phase is the remainder of the cubic boron nitride, and the content of the cubic boron nitride is 50.0~90.0% by volume. The binding phase contains one or more substances selected from Ti carbides, Ti nitrides, Ti carbonitrides, and Ti borides, and one or more substances selected from W₂B and W₂CoB₂. In the X-ray diffraction pattern of the cubic boron nitride sintered body using CuKα rays as the radiation source, the intensity of the diffraction peak attributable to the (111) plane of the cubic boron nitride is denoted as I. A The intensity of the diffraction peak belonging to the (211) plane of the W2B is denoted as I. B The intensity of the diffraction peak with the greater intensity among the diffraction peaks belonging to the (211) plane of W2CoB2 and the diffraction peaks belonging to the (310) plane of W2CoB2 is denoted as I. c At that time, the I B and the I C The total relative to the I A The ratio of [(I)] B +I C ) / I A The value is above 0.25.

Description

Technical Field

[0001] This embodiment relates to cubic boron nitride sintered bodies, methods for manufacturing the same, and tools. Background Technology

[0002] Cubic boron nitride (hereinafter referred to as "cBN") is a material with a hardness comparable to diamond. CBN sintered bodies, formed primarily from cBN particles, possess both wear resistance and chip resistance. Therefore, cBN sintered bodies are mainly used in cutting tools for difficult-to-machine materials such as high-hardness steel. Furthermore, improvements to cBN sintered bodies are being made to further enhance chip resistance to meet the demands of different machining purposes and various uses of cutting tools.

[0003] For example, Patent Document 1 describes a cBN sintered body with excellent strength and heat resistance by setting the weight ratio of W to the total weight of W, Co and Ni to 0.2 to 0.6 and the weight ratio of Co to the total weight of Co and Ni to 0.6 to 0.95.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2000 / 047537 Summary of the Invention

[0007] However, in recent years, the difficulty of machining lightweight workpieces and the significant increase in cutting speeds to reduce machining costs have led to stringent performance requirements for tools using cBN sintered bodies (hereinafter referred to as "cBN tools").

[0008] In view of this situation, the purpose of this embodiment is to provide a cBN sintered body with excellent resistance to defects, as well as a method and tools for manufacturing the same.

[0009] In order to solve the above-mentioned problems, the inventors have repeatedly conducted in-depth research and found that the above-mentioned problems can be solved by adopting the following embodiments.

[0010] [1] A cubic boron nitride sintered body comprising cubic boron nitride and a bonding phase, wherein the bonding phase comprises the remainder of the cubic boron nitride.

[0011] The content of the cubic boron nitride is 50.0~90.0% by volume.

[0012] The bonding phase contains one or more substances selected from Ti carbides, Ti nitrides, Ti carbonitrides, and Ti borides, and one or more substances selected from W2B and W2CoB2.

[0013] In the X-ray diffraction pattern of the cubic boron nitride sintered body using CuKα rays as the radiation source, the intensity of the diffraction peak belonging to the (111) plane of the cubic boron nitride is denoted as I. A The intensity of the diffraction peak belonging to the (211) plane of the W2B is denoted as I. B The intensity of the diffraction peak with the greater intensity among the diffraction peaks belonging to the (211) plane of W2CoB2 and the diffraction peaks belonging to the (310) plane of W2CoB2 is denoted as I. c hour,

[0014] The I B and the I C The total relative to the I A The ratio of [(I)] B +I C ) / I A The value is above 0.25.

[0015] [2] The cubic boron nitride sintered body described in [1] above has a W content of 4.00 to 15.00 by mass.

[0016] [3] According to the cubic boron nitride sintered body described in [1] or [2] above, the I B Relative to the I C The ratio [I] B / I C The value is 0.20~1.00.

[0017] [4] The cubic boron nitride sintered body according to any one of [1] to [3] above contains an average particle size (D) 50 Two or more different cubic boron nitride particles.

[0018] [5] The cubic boron nitride sintered body according to any one of [1] to [4] above has a thermal conductivity of 50.0 W / m·K or higher.

[0019] [6] A tool comprising a cubic boron nitride sintered body as described in any one of [1] to [5] above as a constituent material.

[0020] [7] The tool described in [6] above is for cutting or grinding.

[0021] [8] A method for manufacturing a cubic boron nitride sintered body, comprising the method of manufacturing a cubic boron nitride sintered body according to any one of [1] to [5] above, including:

[0022] A process for pulverizing a bonding material in a container containing a pulverizing medium, wherein the bonding material is the raw material for forming the bonding phase;

[0023] The mixing process of mixing the pulverized binder material and cubic boron nitride particles to obtain a raw material mixture; and

[0024] The sintering process involves subjecting the raw material mixture to pressure heating to obtain a cubic boron nitride sintered body.

[0025] The pulverizing medium used in the pulverizing process of the combined material contains WC.

[0026] According to this embodiment, a cBN sintered body with excellent resistance to defects, a method for manufacturing the same, and tools can be provided. Attached Figure Description

[0027] Figure 1 The image shows the XRD pattern of the cBN sintered body obtained in Example 1.

[0028] Figure 2 The image shows the XRD pattern of the cBN sintered body obtained in Comparative Example 2.

[0029] Figure 3 The image is a reflection electron image (5000x magnification) of the cBN sintered body obtained in Example 1 based on a scanning electron microscope (SEM).

[0030] Figure 4 yes Figure 3 The image shown is a binarized version of the reflected electron image. Detailed Implementation

[0031] In this specification, the range of values ​​indicated by “~” represents the range of minimum and maximum values ​​included before and after the “~”, respectively.

[0032] For example, the expression "X~Y" (where X and Y are real numbers) refers to a range of values ​​above X and below Y. Furthermore, the term "above X" in this specification refers to X and values ​​exceeding X. Additionally, the term "below Y" in this specification refers to Y and values ​​less than Y.

[0033] The lower and upper limits of the numerical ranges described in this specification can be arbitrarily combined with the lower or upper limits of other numerical ranges.

[0034] The lower or upper limit of the numerical range described in this specification may be replaced with the values ​​shown in the embodiments.

[0035] Unless otherwise specified, each ingredient and material listed in this instruction manual may be used alone or in combination of two or more.

[0036] In this specification, for example, when only one element symbol is described as "W", the valence and state of that element are not limited, meaning all elements that form compounds and elements in the metallic state. On the other hand, elements in the metallic state with a valence of 0 are preceded by "metal" as in "metal W".

[0037] Unless otherwise specified, each of the ingredients and materials listed in this instruction manual may be used alone or in combination of two or more.

[0038] The expression "containing XX" as used in this specification includes both the meaning of containing XX in a state where XX has reacted and the meaning of containing only XX, provided that XX can react.

[0039] The mechanisms of action described in this specification are speculative and do not limit the mechanisms by which this embodiment achieves its effects.

[0040] This embodiment also includes any combination of the items described in this specification.

[0041] [Cubic boron nitride sintered body]

[0042] The cubic boron nitride sintered body of this embodiment has cubic boron nitride and a bonding phase, wherein the bonding phase is the remaining portion other than the cubic boron nitride.

[0043] The content of the cubic boron nitride is 50.0~90.0% by volume.

[0044] The bonding phase contains one or more substances selected from Ti carbides, Ti nitrides, Ti carbonitrides, and Ti borides, and one or more substances selected from W2B and W2CoB2.

[0045] In the X-ray diffraction pattern of the cubic boron nitride sintered body using CuKα rays as the radiation source, the intensity of the diffraction peak belonging to the (111) plane of the cubic boron nitride is denoted as I. A The intensity of the diffraction peak belonging to the (211) plane of the W2B is denoted as I. B The intensity of the diffraction peak with the greater intensity among the diffraction peaks belonging to the (211) plane of W2CoB2 and the diffraction peaks belonging to the (310) plane of W2CoB2 is denoted as I.c hour,

[0046] The I B and the I C The total relative to the I A The ratio of [(I)] B +I C ) / I A The value is above 0.25.

[0047] <cBN>

[0048] The cBN content in the cBN sintered body of this embodiment is 50.0~90.0% by volume, preferably 55.0~89.0% by volume, more preferably 63.0~88.0% by volume, even more preferably 68.0~87.0% by volume, preferably 73.0~85.0% by volume, more preferably 75.0~82.0% by volume, and even more preferably 76.0~80.0% by volume.

[0049] If the cBN content is 50.0% by volume or higher, the excellent properties of cBN, such as high hardness, high oxidation resistance, and high thermal conductivity, can be effectively utilized. Even in the event of micro-cracks, the propagation of cracks into the interior of the cBN sintered body can be suppressed, resulting in good resistance to defects. Furthermore, if the cBN content is 90.0% by volume or lower, the aggregation of cBN particles is suppressed, and cBN does not detach and is easily sintered, thus achieving good wear resistance.

[0050] Furthermore, the cBN content in the cBN sintered body is determined by taking the area ratio of cBN in the ground surface of the cBN sintered body as the volume content in the scanning electron microscope (SEM) image. Specifically, it can be determined using the method described in the embodiments.

[0051] The average value of the Freette diameter measured from the cross-sectional SEM image of the cBN contained in the cBN sintered body according to this embodiment is preferably 0.3 to 8.0 μm, more preferably 0.4 to 5.0 μm, and even more preferably 0.5 to 2.0 μm.

[0052] If the average Freret diameter of the aforementioned cBN is above the lower limit, the cBN tends to be firmly held by the bonding phase. Conversely, if the average Freret diameter of the aforementioned cBN is below the upper limit, the fracture toughness of the cBN sintered body tends to be excellent.

[0053] Furthermore, the term "Ferret diameter" in this specification refers to the longest distance among the straight lines connecting any two points on the outer perimeter of the cBN cross section as observed in a cross-sectional photograph of the cBN sintered body.

[0054] The average Freret diameter of cBN is calculated by taking the arithmetic mean of all measurable Freret diameters of cBN within the entire field of view of a 5000x magnification scanning electron microscope (SEM) image of the ground surface of the cBN sintered body. Specifically, it can be calculated using the method described in the examples.

[0055] From the viewpoint of improving the thermal conductivity of the cBN sintered body and further improving its wear resistance and damage resistance, the cBN particles used in the manufacture of the cBN sintered body in this embodiment are preferably those with low porosity.

[0056] Furthermore, the "porosity of cBN particles" in this specification refers only to the porosity calculated from the cBN particles used in the manufacture of the cBN sintered body. When only one type of cBN particle is used, it refers to the porosity of that single cBN particle. When two or more types of cBN particles are used, it refers to the porosity of a mixture of the two or more types of cBN particles.

[0057] The porosity of cBN particles can be calculated using the Ouchiyama formula below, based on the cBN particle size distribution. Furthermore, for details regarding the Ouchiyama formula, please refer to the following literature.

[0058] N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundam., 19, 338 (1980)

[0059] N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundam., 20, 66 (1981)

[0060] N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundam., 23, 490 (1984)

[0061] [Number 1]

[0062]

[0063] [Number 2]

[0064]

[0065] [Number 3]

[0066]

[0067] [Number 4]

[0068]

[0069] [Number 5]

[0070] Φ m Maximum fill fraction;

[0071] Di: Particle size; D̄: Average particle size

[0072] fi: The ratio of the number of particles of each size; w i Mass ratio of particles of different sizes

[0073] ε: Porosity; ε 0i Porosity of a single particle size

[0074] The porosity of cBN particles calculated using the above-mentioned Ouchiyama formula is preferably 50% by volume or less, more preferably 45% by volume or less, even more preferably 40% by volume or less, even more preferably 37% by volume or less, and particularly preferably 35% by volume or less.

[0075] If the porosity of cBN particles is below the aforementioned upper limit, the cBN sintered body of this embodiment tends to have better thermal conductivity, wear resistance, and damage resistance.

[0076] The smaller the porosity of the cBN particles, the better. However, from the point of view of ease of manufacture, it can be 10% or more, 20% or more, or 25% or more.

[0077] A more detailed method for calculating the porosity of cBN particles using the Ouchiyama formula described above is as described in the examples.

[0078] From the viewpoint of reducing the aforementioned porosity to further improve the thermal conductivity, wear resistance, and damage resistance of the cBN sintered body, the cBN sintered body of this embodiment preferably contains an average particle size (D) of [missing information]. 50 Two or more different types of cBN particles, more preferably containing particles with an average particle size (D) 50 (3 or more different types of cBN particles)

[0079] Furthermore, the average particle size (D) of the cBN sintered body in this embodiment is... 50 The number of different cBN particles can be up to 6, up to 5, or up to 4.

[0080] Furthermore, in this specification, the so-called average particle size (D) 50 This refers to the particle size at the 50% cumulative volume of the particle size distribution determined by laser diffraction scattering. Average particle size (D) 50 It can be determined using the methods described in the examples.

[0081] Average particle size (D)50 The average particle size (D) of two or more different cBN particles 50 The average particle size (D) of the two cBN particles with the smallest difference between them. 50 The difference between the two is preferably 0.5 to 3.0 μm, more preferably 1.0 to 2.0 μm, and even more preferably 1.4 to 1.8 μm.

[0082] In addition, the average particle size (D) 50 Among two or more different types of cBN particles, the one with the largest average particle size (D) 50 cBN particles with the smallest average particle size (D) 50 The average particle size (D) of cBN particles 50 The difference between the two is preferably 1.0 to 6.0 μm, more preferably 2.0 to 5.0 μm, and even more preferably 3.0 to 4.0 μm.

[0083] In the presence of average particle size (D) 50 In the case of two or more different types of cBN particles, the average particle size (D) of the two or more types of cBN particles is... 50 The preferred range is from 0.1 to 10.0 μm, more preferably from 0.4 to 7.0 μm, and even more preferably from 0.6 to 5.0 μm.

[0084] From the perspective of reducing the aforementioned porosity, the average particle size (D) 50 Two or more different types of cBN particles, for example, preferably containing an average particle size (D). 50 cBN particles with a diameter greater than 0 μm and less than 2.0 μm (1), and an average particle size (D) 50 cBN particles with a diameter greater than 2.0 μm and less than 4.0 μm (2) and an average particle size (D) 50 (3) Two or three types of cBN particles (3) with a size greater than 4.0 μm and less than 6.0 μm.

[0085] In the case of containing the above-mentioned cBN particles (1), cBN particles (2) and cBN particles (3), the content of the above-mentioned cBN particles (1) relative to the total content of cBN particles (100% by mass) is preferably 5 to 35% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass.

[0086] In the case of containing the above-mentioned cBN particles (1), cBN particles (2) and cBN particles (3), the content of the above-mentioned cBN particles (2) relative to the total content of cBN particles (100% by mass) is preferably 55 to 85% by mass, more preferably 60 to 80% by mass, and even more preferably 65 to 75% by mass.

[0087] In the case of containing the above-mentioned cBN particles (1), cBN particles (2) and cBN particles (3), the content of the above-mentioned cBN particles (3) relative to the total content of cBN particles (100% by mass) is preferably 2 to 25% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass.

[0088] <Binding Phase>

[0089] The bonding phase is the phase that corresponds to the portion other than cBN in the cBN sintered body of this embodiment.

[0090] The combined phase contains one or more substances selected from Ti carbides, Ti nitrides, Ti carbonitrides and Ti borides, and one or more substances selected from W2B and W2CoB2.

[0091] In the X-ray diffraction pattern of the cBN sintered body of this embodiment, using CuKα rays as the radiation source, the intensity of the diffraction peak belonging to the (111) plane of cBN is denoted as I. A The intensity of the diffraction peak belonging to the (211) plane of W2B is denoted as I. B The intensity of the diffraction peak with the greater intensity between the diffraction peaks belonging to the (211) plane of W2CoB2 and the diffraction peaks belonging to the (310) plane of W2CoB2 is denoted as I. c At that time, I B and I C The total relative to I A The ratio of [(I)] B +I C ) / I A The value is above 0.25.

[0092] The cBN sintered body of this embodiment, through the above ratio [(I B +I C ) / I A When the value is above 0.25, the fracture toughness improves and the resistance to breakage becomes excellent. The reason for this is still uncertain, but it is presumed to be as follows.

[0093] In this embodiment, the W2B and W2CoB2 contained in the cBN sintered body are easily formed from fine W sources, therefore it is anticipated that the W2B and W2CoB2 contained in the above-mentioned cBN sintered body will be more readily formed from fine W sources. B +I C ) / I A The cBN sintered body of this embodiment contains a large amount of minute W2B and W2CoB2, with a strength of 0.25 or higher. Furthermore, since W2B and W2CoB2 have the property of being difficult for cracks to propagate, the cBN sintered body of this embodiment is considered to have excellent fracture toughness and thus excellent resistance to breakage.

[0094] The intensity I used to obtain the above diffraction peaks A I B I C And the I mentioned later D The XRD pattern of the cBN sintered body can be obtained using the method described in the examples. The measured XRD pattern of the cBN sintered body can be compared with an inorganic material database to qualitatively identify the components and obtain the diffraction peak intensities for each component. This qualitative analysis and the acquisition of diffraction peak intensities can be performed using commercially available software. For example, the software manufactured by PANalytical under the trade name "X' pertHigh Score Plus" can be used.

[0095] Furthermore, in this embodiment, W2CoB2 is sometimes also represented as B2CoW2 in the inorganic materials database, in addition to W2CoB2. In addition, since the diffraction peaks of the (211) plane and the (310) plane of W2CoB2 appear at similar angles, if a peak belongs to at least one of the (211) plane and the (310) plane of W2CoB2 but it cannot be determined which one it belongs to, it is considered to be equivalent to "the diffraction peak with greater intensity among the diffraction peaks belonging to the (211) plane and the diffraction peaks belonging to the (310) plane of W2CoB2".

[0096] From the perspective of further improving the fracture toughness, wear resistance, and damage resistance of cBN sintered bodies, the above-mentioned ratio [(I] B +I C ) / I A The preferred value is 0.30~4.00, more preferably 0.40~3.00, even more preferably 0.50~2.50, even more preferably 0.60~2.00, even more preferably 0.70~1.60, even more preferably 0.80~1.40, and particularly preferably 0.90~1.20.

[0097] From the perspective of further improving the fracture toughness, wear resistance, and damage resistance of cBN sintered bodies, the intensity I of the diffraction peaks attributed to the W2B(211) plane is... B The intensity I relative to the diffraction peaks belonging to the cBN(111) plane A The ratio [I] B / I A The preferred value is 0.05~0.80, more preferably 0.10~0.60, and even more preferably 0.20~0.45.

[0098] From the perspective of further improving the fracture toughness, wear resistance, and chip resistance of cBN sintered bodies, the intensity I of the diffraction peak with the greater intensity between the diffraction peaks belonging to the W2CoB2 (211) plane and the diffraction peaks belonging to the W2CoB2 (310) plane is determined. c The intensity I relative to the diffraction peaks belonging to the cBN(111) plane A The ratio [I] c / I A The preferred value is 0.20~1.50, more preferably 0.30~1.00, and even more preferably 0.40~0.80.

[0099] From the perspective of further improving the fracture toughness, wear resistance, and damage resistance of cBN sintered bodies, the intensity I of the diffraction peaks attributed to the W2B(211) plane is... B The intensity I of the diffraction peak with greater intensity between the diffraction peaks belonging to the W2CoB2 (211) plane and the diffraction peaks belonging to the W2CoB2 (310) plane. c The ratio [I] B / I C The preferred value is 0.20~1.00, more preferably 0.30~0.70, and even more preferably 0.40~0.50.

[0100] From the perspective of further improving the fracture toughness, wear resistance, and damage resistance of cBN sintered bodies, the intensity I of the diffraction peak attributable to the (110) plane of metallic W is... D The intensity I relative to the diffraction peaks belonging to the cBN(111) plane A The ratio [I] D / I A Preferably, it is 0.10 or less, more preferably 0.01 or less, even more preferably 0.001 or less, and particularly preferably 0.

[0101] From the viewpoint of further improving the wear resistance and damage resistance of cBN sintered body, the W content in the cBN sintered body of this embodiment is preferably 4.00 to 15.00% by mass, more preferably 4.50 to 10.00% by mass, even more preferably 5.00 to 8.50% by mass, and even more preferably 5.20 to 7.00% by mass.

[0102] Furthermore, in this specification, the elemental contents of W and Co, Ti, Al, etc., as described later, can be determined by energy-dispersive X-ray spectroscopy (EDS), specifically, by the method described in the examples.

[0103] From the viewpoint of further improving the wear resistance and damage resistance of cBN sintered body, the Co content in the cBN sintered body of this embodiment is preferably 0.05 to 2.00% by mass, more preferably 0.10 to 1.50% by mass, even more preferably 0.30 to 1.00% by mass, and even more preferably 0.50 to 0.80% by mass.

[0104] The bonding phase contains one or more substances selected from Ti carbides, Ti nitrides, Ti carbonitrides, and Ti borides. The composition can be adjusted depending on the type of bonding material used. In this embodiment, it is preferable to contain one or more substances selected from Ti nitrides and Ti borides, and more preferably, it contains one or more substances selected from TiN and TiB2.

[0105] From the viewpoint of further improving the wear resistance and damage resistance of cBN sintered body, the Ti content in the cBN sintered body of this embodiment is preferably 4.00 to 15.00% by mass, more preferably 6.00 to 13.00% by mass, and even more preferably 8.00 to 12.00% by mass.

[0106] The preferred bonding phase further contains one or more substances selected from Al nitrides, Al borides, and Al oxides. The selection of one or more substances selected from Al nitrides, Al borides, and Al oxides can be adjusted depending on the type of bonding material used. In this embodiment, it is preferable to contain one or more substances selected from Al nitrides and Al oxides, and more preferably, it contains one or more substances selected from AlN and Al2O3.

[0107] From the viewpoint of further improving the wear resistance and damage resistance of cBN sintered body, the Al content in the cBN sintered body of this embodiment is preferably 1.00 to 6.00% by mass, more preferably 1.50 to 5.00% by mass, and even more preferably 2.00 to 4.00% by mass.

[0108] The compounds constituting the binding phase can be characterized, in the same way as W2B, W2CoB2, etc., based on the XRD pattern of the cBN sintered body.

[0109] The bonding phase may also contain compounds other than those mentioned above, such as W₂B, W₂CoB₂, Ti compounds, and Al compounds. For example, the bonding phase may contain: Al-Ti composite oxides; ZrB₂, ZrB₂... 12 HfB2, HfB, HfB 12 VB2, V3B4, V3B 12Borides of Group 4 to 6 transition metal elements such as VB, V5B6, V2B2, NbB2, Nb3B2, NbB, TaB2, Ta2B, Ta3B2, TaB, Ta3B4, CrB, CrB4, Cr2B, Cr2B3, Cr5B3, CrB2, MoB, Mo2B5, MoB4, Mo2B, MoB2, WB, WB4, etc.; ZrN x (0 < x ≤ 1), Hf3N2, HfN x (0 < x ≤ 1), Hf4N3, VN x (0 < x ≤ 1), V2N, NbN, Nb4N3, Nb2N, TaN x (0 < x ≤ 1), Ta3N5, Ta4N, Ta2N, Cr2N, CrN x (0 < x ≤ 1), Nitrides of Group 4 to 6 transition metal elements such as WN, W2N, etc.; Solid solutions of each compound including the above compounds; and so on. However, in the cBN sintered body, the content of each Group 4 to 6 transition metal element other than Ti and W is preferably as small as possible. The content of each Group 4 to 6 transition metal element other than Ti and W is preferably 1000 mass ppm or less, more preferably 100 mass ppm or less.

[0110] In addition, in the cBN sintered body of the present embodiment, for example, there are cases where unavoidable impurities derived from the compounding raw materials are included. Examples of the above unavoidable impurities include Li, Mg, Ca, Al, Si, Ti, C, B, S, P, Ga, Co, Ni, Mn, Fe, Cl, W, their compounds, etc., and impurities that overlap with the above other compounds may also be included.

[0111] <Vickers hardness>

[0112] From the viewpoint of being suitably used for cutting processing of high-hardness workpieces, etc., the Vickers hardness of the cBN sintered body of the present embodiment is preferably 3000 HV or more, more preferably 3200 HV or more, further preferably 3300 HV or more, still further preferably 3400 HV or more, and particularly preferably 3450 HV or more.

[0113] The higher the Vickers hardness of the cBN sintered body of the present embodiment, the more preferable it is. However, from the viewpoint of easy manufacturability, it can be 5000 HV or less, can be 4000 HV or less, and can be 3800 HV or less.

[0114] The Vickers hardness of the cBN sintered body can be measured by the method described in the examples.

[0115] <Thermal conductivity>

[0116] From the viewpoint of further improving wear resistance and damage resistance, the thermal conductivity of the cBN sintered body in this embodiment is preferably 50.0 W / m·K or higher, more preferably 54.0 W / m·K or higher, even more preferably 55.0 W / m·K or higher, even more preferably 56.0 W / m·K or higher, and particularly preferably 58.0 W / m·K or higher.

[0117] In this embodiment, a higher thermal conductivity of the cBN sintered body is preferred, but from the viewpoint of ease of manufacture, it can be 70.0 W / m·K or less, 67.0 W / m·K or less, or 65.0 W / m·K or less.

[0118] The thermal conductivity of the cBN sintered body can be determined using the method described in the examples.

[0119] [Manufacturing method of cBN sintered body]

[0120] The method for manufacturing cBN sintered bodies according to this embodiment includes:

[0121] A process for pulverizing a bonding material in a container containing a pulverizing medium, wherein the bonding material is the raw material for forming the bonding phase;

[0122] The mixing process of mixing the pulverized binder material and cubic boron nitride particles to obtain a raw material mixture; and

[0123] The sintering process involves subjecting the raw material mixture to pressure heating to obtain a cubic boron nitride sintered body.

[0124] The pulverizing medium used in the pulverizing process of the combined material contains WC.

[0125] The following describes each step of the manufacturing method of the cBN sintered body according to this embodiment.

[0126] <Combined Material Crushing Process>

[0127] The process of pulverizing the combined materials involves pulverizing the combined materials in a container that contains pulverizing media.

[0128] The binder material being pulverized in the binder material pulverization process preferably contains Ti-containing raw materials, or it can be only Ti-containing raw materials, or it can be a mixture of Ti-containing raw materials and raw materials other than Ti-containing raw materials.

[0129] Ti-containing raw materials can be elemental or compounds.

[0130] As Ti-containing raw materials, TiN and TiAl3 are preferred, and those containing both TiN and TiAl3 are more preferred. By using TiN and TiAl3 as Ti-containing raw materials, TiN, AlN, Al2O3, TiB2, etc. can be generated in the bound phase.

[0131] From the viewpoint that the desired particle size can be easily obtained under moderate grinding conditions, the average particle size (D) of Ti-containing raw materials supplied for the material grinding process is... 50 The average particle size (D) of the Ti-containing raw material is preferably 30.0 μm or less, more preferably 25.0 μm or less, and even more preferably 20.0 μm or less. 50 The size can be greater than 0.1μm, greater than 0.3μm, or greater than 0.5μm.

[0132] From the viewpoint that the desired particle size can be easily obtained under moderate pulverization conditions, the average particle size (D) of TiN supplied for the material pulverization process is... 50 The average particle size of TiN is preferably 2.5 μm or less, more preferably 2.0 μm or less, and even more preferably 1.5 μm or less. 50 The size can be greater than 0.1μm, greater than 0.3μm, or greater than 0.5μm.

[0133] From the viewpoint that the desired particle size can be easily obtained under moderate pulverization conditions, the average particle size (D) of TiAl3 supplied for the material pulverization process is... 50 The average particle size of TiAl3 is preferably 30.0 μm or less, more preferably 25.0 μm or less, and even more preferably 20.0 μm or less. 50 The size can be 1.0μm or larger, 5.0μm or larger, or 10.0μm or larger.

[0134] In the material crushing process, the material is crushed in a container containing crushing media containing WC.

[0135] In the cBN sintered body manufacturing method of this embodiment, the binder material is pulverized using a pulverizing medium containing WC, and the raw material contains WC derived from the pulverizing medium. This WC is transformed into W2B, W2CoB2, etc., through a subsequent sintering process, thereby obtaining the cBN sintered body of this embodiment. Therefore, in the binder material pulverizing process of this embodiment, the conditions are preferably adjusted to form ideal amounts of W2B and W2CoB2. For example, by setting the pulverizing conditions in the binder material pulverizing process to be more stringent than usual, the raw material contains many tiny WC particles derived from the pulverizing medium, making it easier to form W2B and W2CoB2.

[0136] The grinding medium can be any grinding medium containing WC, but it is preferred to have grinding media containing both WC and Co, and even more preferably grinding media made of superhard alloy containing both WC and Co.

[0137] The WC content in the pulverizing medium is preferably 70-97% by mass, more preferably 76-92% by mass, and even more preferably 82-88% by mass.

[0138] The Co content in the pulverizing medium is preferably 3 to 30% by mass, more preferably 8 to 24% by mass, and even more preferably 12 to 18% by mass.

[0139] The pulverizing method used in the material pulverizing process is not particularly limited as long as it uses pulverizing media; examples include ball mills and rod mills. However, from a productivity point of view, ball mills are preferred. That is, the pulverizing media is preferably balls used in a ball mill. Furthermore, the ball mill in this specification can also be referred to as a bead mill.

[0140] The ball mill can be a rotary ball mill, a vibratory ball mill, or a combination of rotary and vibratory ball mills, but from a productivity point of view, a rotary ball mill is preferred. The rotary ball mill can be a conventional self-rotating ball mill or a planetary ball mill.

[0141] When using a ball mill, the mill pot material preferably contains WC, more preferably contains Co in addition to WC, and even more preferably is made of a superhard alloy containing both WC and Co. The suitable content of WC and Co in the mill pot material is the same as that in the case of the grinding media.

[0142] The diameter of the balls used in the ball mill is preferably 0.1 to 20.0 mm, more preferably 0.5 to 10.0 mm, and even more preferably 1.0 to 5.0 mm.

[0143] Grinding using a ball mill can be either dry or wet, but wet grinding is preferred from the viewpoint of achieving more uniform grinding. Examples of dispersion media used in wet grinding include acetone, hexane, 2-propanol, ethanol, and heptane. Acetone is preferred. One dispersion medium can be used alone, or two or more can be used in combination.

[0144] When the pulverization process of the binding material is carried out in a wet manner, the content of the pulverized material in the slurry obtained by mixing the pulverized material containing the binding material and the dispersion medium is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably 30 to 50% by mass.

[0145] The pulverization can be carried out in an air atmosphere or in an inert gas atmosphere such as N2 gas.

[0146] When using a rotary ball mill in the material crushing process, the crushing time, rotation speed, ball filling amount, and filling amount of the material to be crushed should preferably be appropriately determined based on the crushing scale and the target particle size.

[0147] The grinding time of the ball mill in the material grinding process using a rotary ball mill can be, for example, 3 to 7 hours.

[0148] The rotational speed of the ball mill used in the material crushing process of a rotary ball mill can be, for example, 150 to 300 rpm.

[0149] In the material crushing process using a rotary ball mill, the amount of balls fed into the grinding jar can be, for example, 15 to 35 times the internal volume of the grinding jar.

[0150] In the material crushing process using a rotary ball mill, the amount of material to be crushed fed into the grinding jar can be, for example, 20 to 40 times the internal volume of the grinding jar.

[0151] The crushing process can be carried out only once, or it can be carried out more than twice as needed.

[0152] From the perspective of homogenizing the composition of cBN sintered bodies, the average particle size (D) of the pulverized binder material obtained through the binder material pulverization process is... 50 The preferred size is 0.10~2.5μm, more preferably 0.30~1.8μm, and even more preferably 0.50~1.1μm.

[0153] <Mixed Process>

[0154] The mixing process is the process of mixing the above-mentioned pulverized binder material with cBN particles to obtain a raw material mixture.

[0155] cBN particles, for example, can be well-suited to be materials obtained by micro-pulverizing cBN with a purity of 99.9% or higher, synthesized under ultra-high pressure and high temperature above 3 GPa and 1200℃, and adjusting the particle size and shape.

[0156] Regarding the preferred average particle size (D) of cBN particles 50 The description of ) is as described in the description of [cBN] above.

[0157] The preferred amount of cBN particles is one that brings the cBN content in the resulting cBN sintered body to within the aforementioned suitable range.

[0158] The mixing process preferably involves mixing the raw materials, including the pulverized components of each binding material and cBN particles, in a container holding the pulverizing medium.

[0159] The mixing method in the mixing process can be the same as the pulverization method listed in the material pulverization process, and the preferred method is also the same. That is, the mixing in the mixing process is preferably carried out using a rotary ball mill. When the mixing is carried out wet using a rotary ball mill, the content of the raw material in the slurry obtained by mixing the raw material and the dispersion medium is preferably 50 to 80% by mass, more preferably 55 to 75% by mass, and even more preferably 60 to 70% by mass.

[0160] Mixing can be carried out in an air atmosphere or in an inert gas atmosphere such as N2 gas.

[0161] When using a rotary ball mill in the mixing process, the mixing time, rotation speed, ball filling amount, and filling amount of the object to be mixed should preferably be determined appropriately based on the mixing scale.

[0162] The mixing time of the ball mill in the mixing process using a rotary ball mill can be, for example, 2 to 6 hours.

[0163] The rotational speed of the ball mill in the mixing process using a rotary ball mill can be, for example, 100 to 200 rpm.

[0164] In the mixing process using a rotary ball mill, the amount of balls fed into the grinding jar can be, for example, 25 to 40 times the internal volume of the grinding jar.

[0165] In the mixing process using a rotary ball mill, the amount of raw material fed into the mill jar can be, for example, 40 to 60 times the internal volume of the mill jar.

[0166] <Heat Treatment Process>

[0167] Alternatively, the raw material mixture obtained through the mixing process can be subjected to heat treatment for degassing as needed to produce a heat-treated raw material mixture.

[0168] From the viewpoint of uniform reaction sintering of the bonded phase and densification of the sintered body, the temperature for degassing heat treatment is preferably below 800°C.

[0169] Furthermore, from the viewpoint of thoroughly removing impurities such as organic matter and densifying the cBN sintered body, the heat treatment temperature is preferably 500°C or higher.

[0170] Based on the above viewpoints, the heat treatment temperature is more preferably 550~750℃, and even more preferably 600~700℃.

[0171] From the viewpoint of efficient degassing, heat treatment is preferably carried out under a vacuum atmosphere, preferably at a pressure of 1.0 × 10⁻⁶.-3 The test is conducted under conditions below Pa.

[0172] The heat treatment time is set appropriately according to the amount of raw material mixture being treated and the type of dispersion medium used in the mixing process, but it is usually 0.1 to 10 hours, preferably 1 to 3 hours.

[0173] <Sintering Process>

[0174] The sintering process involves pressurizing and heating the raw material mixture obtained in the mixing process to obtain a cubic boron nitride sintered body. Furthermore, the raw material mixture obtained in the mixing process can be a heat-treated raw material mixture obtained in the heat treatment process, or a raw material mixture obtained without undergoing a heat treatment process.

[0175] From the viewpoint of densification of cBN sintered body, the maximum temperature in the pressure heating treatment is preferably 1200~1600℃, more preferably 1250~1550℃, and even more preferably 1300~1500℃.

[0176] From the viewpoint of densifying the cBN sintered body, the maximum pressure in the pressurized heat treatment is preferably 3.0 GPa or higher, more preferably 3.5 GPa or higher, and even more preferably 4.0 GPa or higher. The maximum pressure in the pressurized heat treatment can be 7.0 GPa or lower, 6.0 GPa or lower, or 5.0 GPa or lower.

[0177] From the viewpoint of suppressing the oxidation of the raw material mixture during pressurized heat treatment and producing the desired cBN sintered body, the atmosphere during pressurized heat treatment is preferably set to an inert gas atmosphere. Examples of inert gases include Ar gas and N2 gas. One of these gases can be used alone, or two or more can be used in combination.

[0178] [tool]

[0179] The tool of this embodiment includes the cBN sintered body of this embodiment as a constituent material.

[0180] As described above, the cBN sintered body of this embodiment has high hardness and excellent wear resistance and chipping resistance, and is therefore a suitable material for tools, especially cutting or grinding tools.

[0181] Example

[0182] The following description is based on an example, but the implementation method is not limited to the example.

[0183] Average particle size (D) 50 ), 10% particle size (D 10 ) and 90% particle size (D90 [Determination method of )]

[0184] The particle size distribution was measured using a particle size analyzer ("LA-920", manufactured by Horiba Manufacturing Co., Ltd.). Then, from the obtained particle distribution, the 10% particle size (D) representing 10% of the cumulative volume was measured. 10 ), average particle size (D) 50 ) and 90% of the cumulative volume of 90% of the particle size (D) 90 ).

[0185] [Method for calculating the porosity of cBN particles]

[0186] The porosity of cBN particles is calculated using the Ouchiyama formula mentioned above.

[0187] Furthermore, the particle size (D) in the Ōuchiyama formula i The above-mentioned average particle size (D) is used. 50 The particle size of cBN particles obtained by the above method, the average particle size (D with a horizontal line), is determined by the above method. 50 The method for determining the average particle size (D) of cBN particles obtained is as follows: 50 The ratio of the number of particles of each particle size (f) i ) and the mass ratio of particles of each size (w) i The value (ε) is obtained based on the particle size distribution of cBN particles, representing the porosity (ε) for a single particle size. 0i The values ​​are calculated assuming that the cBN particles of each size are spheres. When mixing two or more types of cBN particles, the above parameters can be calculated based on the particle size distribution and mixing amount of each cBN particle.

[0188] [Methods for determining cBN content and Ferrette diameter]

[0189] The cBN sintered body samples obtained in each example were used as the test objects, and reflected electron images were captured at 5000x magnification using a scanning electron microscope (SEM) ("S-5500", manufactured by Hitachi High Technology Co., Ltd.). The captured images contained black, white, and gray regions. Energy-dispersive X-ray spectroscopy (EDS) analysis of each region confirmed that the black regions were cBN, and the white and gray regions were the bonding phase.

[0190] The captured image was binarized using image processing software. The black portion representing cBN and the white portion representing the binding phase were identified. The area ratio of the black portion in the entire field of view of the binarized image was calculated. The arithmetic mean of the three fields of view was taken as the cBN content (unit: volume %).

[0191] As a representative example Figure 3 This represents the reflected electron image of the sintered body of Example 1. Figure 4 This represents the binarized image. Furthermore, the size of one field of view is set to 25.0 μm horizontally and 17.4 μm vertically, and the total area of ​​the three fields of view is 1305.0 μm. 2 .

[0192] In addition, the Freret diameters of all measurable cBNs in the entire field of view of the binarized image of the reflected electron image taken at 5000x magnification are calculated using image processing software, and their arithmetic mean is taken as the Freret diameter of the cBN (unit: μm).

[0193] [Elemental Analysis]

[0194] The cBN sintered body samples obtained in each example for evaluation were used as the test objects, and energy-dispersive X-ray spectroscopy (EDS) was performed to determine the elemental concentrations of B, N, O, C, Al, Ti, Co, and W in the cBN sintered body. Furthermore, the elemental concentrations were measured under the following conditions over the entire field of view, and the average value of 10 fields of view was taken. The EDS measurement conditions are shown below.

[0195] Measurement device: JSM-6510LA (manufactured by Nippon Electronics Co., Ltd.)

[0196] EDS analysis software: Analysis Station (manufactured by NEC Corporation)

[0197] Accelerating voltage: 20.0kV (irradiation current: 1.00000nA)

[0198] Multiplier: 2000x

[0199] Energy range: 0-20keV

[0200] [Analytical Methods for the Composition of Sintered Bodies]

[0201] The cBN sintered body samples obtained in each example for evaluation were used as the test objects, and XRD measurements were performed using an X-ray diffraction apparatus (“X'pert PRO”, manufactured by PANalytical). The measurements were performed under the conditions of CuKα rays, output voltage of 40 kV, output current of 40 mA, sampling amplitude of 0.0167°, scanning speed of 0.4178° / s, and measurement range of 2θ = 10~80°.

[0202] The XRD patterns obtained were qualitatively analyzed by comparing them with an inorganic materials database using the software "X'pert High Score Plus" manufactured by PANalytical. The composition detected by XRD analysis is shown in Table 1, "Sintered Body Composition".

[0203] [Method for determining the intensity ratio of diffraction peaks]

[0204] In the XRD pattern of the section on [Analysis Methods for the Composition of Sintered Bodies] above, the diffraction peak intensity of the cBN(111) plane near 2θ=43.30° is denoted as I. A Let I denote the intensity of the diffraction peak near 2θ = 40.90° belonging to the W2B(211) plane. B Let I denote the intensity of the diffraction peak with greater intensity between the diffraction peaks belonging to the W2CoB2 (211) plane and the diffraction peaks belonging to the W2CoB2 (310) plane near 2θ=43.10°. c Let I denote the intensity of the diffraction peak at the (110) plane of metal W near 2θ=40.30°. D The intensity ratios of each diffraction peak were calculated separately. B / I A ]、[I C / I A ]、[I B / I C ]、[I D / I A ] and [(I B +I C ) / I A ].

[0205] As a representative example, in Figure 1 The image shows the XRD pattern of the cBN sintered body obtained in Example 1, with 2θ ranging from 39° to 44°. Figure 2 The XRD pattern of the cBN sintered body obtained in Comparative Example 2 is shown in the range of 2θ = 39° to 44°.

[0206] [Manufacturing of Cubic Boron Nitride Sintered Bodies]

[0207] Examples 1-3

[0208] (Combined with the material crushing process)

[0209] TiN (average particle size (D) 50 =1.2μm) 7.7g, TiAl3 (average particle size (D) 50)(= 19.8 μm) 2.6 g, the dispersion medium (acetone) 21 ml, and 161 g of balls were put into the grinding pot of a planetary ball mill (product name "Planetary Ball Mill", manufactured by Fritsch), and grinding was carried out under the following grinding conditions. Furthermore, both the grinding pot and the balls of the planetary ball mill were made of cemented carbide (composition: WC content was about 85% by mass, Co content was about 15% by mass). The height of the cylindrical grinding pot was 23 mm, the inner diameter was φ65 mm, and the ball diameter of the balls was 1.3 mm.

[0210] <Combined material grinding conditions>

[0211] · Raw material (slurry) filling amount: about 32% by volume relative to the internal volume of the grinding pot

[0212] · Ball filling amount: about 24% by volume relative to the internal volume of the grinding pot

[0213] · Atmosphere: Air atmosphere

[0214] · Rotation speed: 270 rpm

[0215] · Grinding time: 5 hours

[0216] (cBN particle and combined material mixing process)

[0217] 31 g of cBN particles, 8 ml of the dispersion medium (acetone), and 54 g of balls (ball diameter 3.0 mm) described in Table 1 were additionally put into the grinding pot that had completed the above combined material grinding process, and mixing was carried out under the following mixing conditions to obtain a slurry of the raw material mixture. The material of the balls was the same as that of the balls used in the combined material grinding process.

[0218] <cBN particle and combined material mixing conditions>

[0219] · Raw material (slurry) filling amount: about 54% by volume relative to the internal volume of the grinding pot

[0220] · Ball filling amount: about 32% by volume relative to the internal volume of the grinding pot

[0221] · Atmosphere: N2 gas atmosphere

[0222] · Rotation speed: 140 rpm [[ID=四十]]

[0223] · Mixing time: 4 hours

[0224] Furthermore, the details of the cBN particles (1) to (3) shown in Table 1 are as follows.

[0225] cBN particle (1): 10% particle size (D 10 ) = 0.56 μm, average particle size (D 50=0.86μm, 90% particle size (D) 90 =1.49μm

[0226] cBN particles (2): 10% particle size (D) 10 =1.92μm, average particle size (D) 50 =2.93μm, 90% particle size (D) 90 =4.31μm

[0227] cBN particles (3): 10% particle size (D) 10 =3.06μm, average particle size (D) 50 =4.60μm, 90% particle size (D) 90 =6.42μm

[0228] (Heat treatment process)

[0229] The slurry obtained above was dried at 70°C for 5 hours under a nitrogen atmosphere, and then subjected to a 1.0×10⁻⁶ ppm drying process. -3 Degassing was performed by heat treatment at 650°C for 0.5 hours under a vacuum atmosphere below Pa to obtain heat-treated powder.

[0230] (Sintering process)

[0231] Under an N2 atmosphere, the aforementioned heat-treated powder was stacked on a superhard alloy support plate and then subjected to pressure heating at 4.5 GPa and 1500 °C for 1 hour to prepare a cBN sintered body (approximately 30 mm in diameter and 4 mm in thickness). The upper surface of the cBN sintered body (the contact surface with the hard alloy support plate being the lower surface) was ground with a #400 diamond grinding stone to prepare a cBN sintered body sample for evaluation.

[0232] Example 4

[0233] (Combined with the material crushing process)

[0234] TiN (average particle size (D) 50 =1.2μm) 0.9g, TiC (average particle size (D 50 =0.70μm) 5.8g, TiAl3 (average particle size (D 50 3.6 g of a 19.8 μm particle, 21 ml of dispersion medium (acetone), and 161 g of balls were added to the jar of a planetary ball mill (product name "planetary ball mill", manufactured by Fritsch) and pulverized under the same conditions as the pulverization of the binder material in Example 1. Furthermore, the specifications of the planetary ball mill and the balls were the same as in Example 1.

[0235] (The mixing process of cBN particles and binding materials)

[0236] 31g of cBN particles, 8ml of dispersion medium (acetone), and 54g of balls (3.0mm in diameter) as listed in Table 1 were added to the grinding jar that had completed the above-mentioned material crushing process. The mixture was then stirred under the same conditions as in Example 1 to obtain a slurry of the raw material mixture. The material of the balls was the same as that used in the material crushing process.

[0237] (Heat treatment process and firing process)

[0238] Using the slurry obtained above, heat treatment and sintering processes were carried out under the same conditions as in Example 1, thereby obtaining cBN sintered body samples for evaluation.

[0239] Example 5

[0240] (Combined with the material crushing process)

[0241] TiN (average particle size (D) 50 =1.2μm) 9.3g, TiAl3 (average particle size (D) 50 3.1 g of a particle size of 19.8 μm, 21 ml of dispersion medium (acetone), and 161 g of balls were added to the jar of a planetary ball mill (product name "planetary ball mill", manufactured by Fritsch) and pulverized under the same conditions as the pulverization of the binder material in Example 1. Furthermore, the specifications of the planetary ball mill and the balls were the same as in Example 1.

[0242] (The mixing process of cBN particles and binding materials)

[0243] 28.9 g of cBN particles, 8 ml of dispersion medium (acetone), and 54 g of balls (3.0 mm in diameter) as listed in Table 1 were added to the grinding jar that had completed the above-mentioned material crushing process. The mixture was then stirred under the same conditions as in Example 1 to obtain a slurry of the raw material mixture. The material of the balls was the same as that used in the material crushing process.

[0244] (Heat treatment process and firing process)

[0245] Using the slurry obtained above, a heat treatment process and a sintering process were performed under the same conditions as in Example 1, thereby obtaining a cBN sintered body sample for evaluation.

[0246] Example 6

[0247] (Combined with the material crushing process)

[0248] TiN (average particle size (D) 50 =1.2μm) 10.8g, TiAl3 (average particle size (D)50 3.7 g of a material with a particle size of 19.8 μm, 21 ml of dispersion medium (acetone), and 161 g of balls were added to the jar of a planetary ball mill (product name "planetary ball mill", manufactured by Fritsch) and pulverized under the same conditions as the material pulverization in Example 1. Furthermore, the specifications of the planetary ball mill and the balls were the same as in Example 1.

[0249] (The mixing process of cBN particles and binding materials)

[0250] 26.8 g of cBN particles, 8 ml of dispersion medium (acetone), and 54 g of balls (3.0 mm in diameter) as listed in Table 1 were added to the grinding jar that had completed the above-mentioned material crushing process. The mixture was then stirred under the same conditions as in Example 1 to obtain a slurry of the raw material mixture. The material of the balls was the same as that used in the material crushing process.

[0251] (Heat treatment process and firing process)

[0252] Using the slurry obtained above, a heat treatment process and a sintering process were performed under the same conditions as in Example 1, thereby obtaining a cBN sintered body sample for evaluation.

[0253] Example 7

[0254] (Combined with the material crushing process)

[0255] TiN (average particle size (D) 50 =1.2μm) 12.3g, TiAl3 (average particle size (D) 50 4.2 g of a material with a particle size of 19.8 μm, 21 ml of dispersion medium (acetone), and 161 g of balls were added to the jar of a planetary ball mill (product name "planetary ball mill", manufactured by Fritsch) and pulverized under the same conditions as the material pulverization in Example 1. Furthermore, the specifications of the planetary ball mill and the balls were the same as in Example 1.

[0256] (The mixing process of cBN particles and binding materials)

[0257] 24.8 g of cBN particles, 8 ml of dispersion medium (acetone), and 54 g of balls (3.0 mm in diameter) as listed in Table 1 were added to the grinding jar that had completed the above-mentioned material crushing process. The mixture was then stirred under the same conditions as in Example 1 to obtain a slurry of the raw material mixture. The balls were made of the same material as those used in the material crushing process.

[0258] (Heat treatment process and firing process)

[0259] Using the slurry obtained above, a heat treatment process and a sintering process were performed under the same conditions as in Example 1, thereby obtaining a cBN sintered body sample for evaluation.

[0260] Comparative Example 1

[0261] Based on Example 1, the types of cBN particles were changed to those listed in Table 1, the amount of cBN particles was changed to 26.1g, the amount of TiN was changed to 9.1g, the amount of TiAl3 was changed to 4.9g, the amount of balls added in the bonding material crushing process was changed to 107g, and the crushing time in the bonding material crushing process was changed to 4 hours. Otherwise, the process was the same as in Example 1, and cBN sintered bodies and cBN sintered body samples for evaluation were obtained.

[0262] Comparative Example 2

[0263] Based on Example 1, the amount of balls added in the material crushing process was changed to 107g, the ball diameter was changed to 3.0mm, the crushing time in the material crushing process was changed to 4 hours, and no additional balls were added in the mixing process of cBN particles and binder materials. Otherwise, the process was the same as in Example 1, and cBN sintered bodies and cBN sintered body samples for evaluation were obtained.

[0264] Comparative Example 3

[0265] (Combined with the material crushing process)

[0266] TiN (average particle size (D) 50 =1.2μm) 14.4g, TiC (average particle size (D 50 =0.70μm) 4.2g, TiAl3 (average particle size (D 50 7.4 g of cBN particles (19.8 μm), 15.3 g of cBN particles as described in Table 1, 21 ml of dispersion medium (acetone), and 107 g of balls (3.0 mm in diameter) were added to the jar of a planetary ball mill (product name "planetary ball mill", manufactured by Fritsch). The mixture was then pulverized and mixed under the following conditions to obtain a slurry of the raw material mixture. Furthermore, the specifications of the planetary ball mill and the balls were the same as in Example 1.

[0267] <Grinding and Mixing Conditions>

[0268] • Raw material (slurry) filling amount: approximately 54% by volume relative to the internal volume of the grinding jar

[0269] • Ball filling amount: approximately 24% of the internal volume of the grinding jar

[0270] • Atmosphere: The atmosphere of the air

[0271] Rotation speed: 190 rpm

[0272] • Grinding and mixing time: 6 hours

[0273] (Heat treatment process and firing process)

[0274] Using the slurry obtained above, a heat treatment process and a sintering process were performed under the same conditions as in Example 1, thereby obtaining a cBN sintered body sample for evaluation.

[0275] [Evaluation Method]

[0276] The cBN sintered body samples obtained in each example were evaluated as follows. The evaluation results are summarized in Table 1.

[0277] <Method for determining Vickers hardness>

[0278] According to JIS Z 2244:2009, the Vickers hardness of the cBN sintered body specimens used for evaluation in each case was measured using the product name "HMV-G21" (manufactured by Shimadzu Corporation) as the measuring device under the conditions of a load of 9.8 N, a holding time of 15 seconds, and 25 °C.

[0279] <Methods for determining thermal conductivity>

[0280] A thermal conductivity test specimen (thickness: 0.80 mm, diameter: 10.0 mm φ) was cut from the cBN sintered body sample used for evaluation, and the surface of the obtained specimen was blackened with a black spray. The thermal diffusivity of the specimen was measured using a laser scintillation analyzer (NETZSCH, product name "LFA457") with the thickness direction as the heat flow direction. Furthermore, the specific heat of the specimen was measured using this device, and the density of the specimen was determined based on its size and weight. Based on these results, the thermal conductivity in the thickness direction of the cBN sintered body sample used for evaluation was calculated using the following formula.

[0281] Thermal conductivity (W / (m·K)) = specific heat (J / (kg·K)) × density (kg / m³) 3 ) × thermal diffusivity (m 2 / Second)

[0282] <Methods for determining fracture toughness>

[0283] The fracture toughness value was determined using the IF method (indenter indentation method) according to JIS R 1607:2015 "Test method for fracture toughness of fine ceramics at room temperature". The testing apparatus used was the product name "HMV-G21" (manufactured by Shimadzu Corporation). Ten cBN sintered body specimens for evaluation were tested under the conditions of a maximum load of 9.8 N, an indenter insertion time of 5 seconds, and 25°C. The arithmetic mean of these tests was taken as the fracture toughness value.

[0284] <Cutting Evaluation 1>

[0285] Cutting tools conforming to ISO standard CNGA120404 were fabricated from the cBN sintered bodies obtained in the various examples. Using these cutting tools, cutting tests were conducted on the workpiece materials under the following cutting conditions. The maximum number of machining operations was set to 1500, and the number of operations until tool breakage was used as an indicator of breakage resistance. Furthermore, for cutting tools with a machining operation count of 1500, the wear amount of the cutting tool after 1500 machining operations was measured.

[0286] (Cutting conditions)

[0287] • Cutting speed: 145 m / min

[0288] • Allowance: φ0.33mm

[0289] • Feed rate: 0.20 (mm / rev)

[0290] • Type of material being machined: austenitic sintered alloy

[0291] • Test ambient temperature: 25℃

[0292] <Cutting Evaluation 2>

[0293] Cutting tools conforming to ISO standard CNGA120404 (tool tip shape: sharp cutting edge) were fabricated from the cBN sintered bodies obtained in the various examples. Using the obtained cutting tools, cutting tests were conducted on the workpiece material under the following cutting conditions, and the VB wear (mm) of the cutting tools after cutting evaluation was determined.

[0294] (Cutting conditions)

[0295] • Cutting method: Continuous cutting (dry)

[0296] • Cutting speed: 400 m / min

[0297] • Feed rate: 0.2mm

[0298] • Feed rate: 0.2 (mm / rev)

[0299] Processing distance: 330m / pass

[0300] • Type of material to be machined: FC 250 (cast iron round bar, hardness HB190)

[0301] • Test ambient temperature: 25℃

[0302] <Cutting Evaluation 3>

[0303] Cutting tools conforming to ISO standard CNGA120404 (tool tip shape: sharp cutting edge) were fabricated from the cBN sintered bodies obtained in the various examples. Using the obtained cutting tools, cutting tests were conducted on the workpiece material under the following cutting conditions, and the number of intermittent impacts until the cutting tool broke was determined.

[0304] (Cutting conditions)

[0305] • Cutting method: Intermittent cutting (dry)

[0306] • Cutting speed: 150 m / min

[0307] • Feed rate: 0.2mm

[0308] • Feed rate: 0.15 (mm / rev)

[0309] Processing distance: 150m / pass

[0310] • Type of material to be machined: SCM415 (8 grooves) (hardened steel, hardness HRC62~60)

[0311] • Test ambient temperature: 25℃

[0312]

[0313] In Table 1, "ND" means not detected.

[0314] In Table 1, "NE" means that no evaluation was conducted.

[0315] As shown in Table 1, the cBN sintered bodies of Examples 1 to 7 of this embodiment exhibit excellent resistance to defects.

Claims

1. A cubic boron nitride sintered body, comprising cubic boron nitride and a bonding phase, wherein the bonding phase is the remainder of the cubic boron nitride. The content of the cubic boron nitride is 50.0~90.0% by volume. The bonding phase contains one or more substances selected from Ti carbides, Ti nitrides, Ti carbonitrides, and Ti borides, and one or more substances selected from W2B and W2CoB2. In the X-ray diffraction pattern of the cubic boron nitride sintered body using CuKα rays as the radiation source, the intensity of the diffraction peak belonging to the (111) plane of the cubic boron nitride is denoted as I. A The intensity of the diffraction peak belonging to the (211) plane of the W2B is denoted as I. B The intensity of the diffraction peak with the greater intensity among the diffraction peaks belonging to the (211) plane of W2CoB2 and the diffraction peaks belonging to the (310) plane of W2CoB2 is denoted as I. c hour, The I B and the I C The total relative to the I A The ratio is (I) B +I C ) / I A It is above 0.

25.

2. The cubic boron nitride sintered body according to claim 1, The W content is 4.00~15.00 by mass.

3. The cubic boron nitride sintered body according to claim 1 or 2, The I B Relative to the I C The ratio is I B / I C The value is 0.20~1.

00.

4. The cubic boron nitride sintered body according to claim 1 or 2, Contains average particle size D 50 Two or more different types of cubic boron nitride particles.

5. The cubic boron nitride sintered body according to claim 1 or 2, The thermal conductivity is above 50.0 W / m·K.

6. A tool comprising the cubic boron nitride sintered body as described in claim 1 or 2 as a constituent material.

7. The tool according to claim 6, It is used for cutting or grinding.

8. A method for manufacturing a cubic boron nitride sintered body, comprising: A process for pulverizing a bonding material in a container containing a pulverizing medium, wherein the bonding material is the raw material for forming the bonding phase; The mixing process of mixing the pulverized binder material and cubic boron nitride particles to obtain a raw material mixture; and The sintering process involves subjecting the raw material mixture to pressure heating to obtain a cubic boron nitride sintered body. The pulverizing medium used in the pulverizing process of the combined material contains WC.

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