JP6912685B2 - Cubic boron nitride sintered body - Google Patents

Description

The present disclosure relates to a cubic boron nitride sintered body. This application claims priority based on Japanese Patent Application No. 2019-13302, which is a Japanese patent application filed on July 18, 2019. All the contents of the Japanese patent application are incorporated herein by reference.

As a high-hardness material used for cutting tools and the like, there is a cubic boron nitride sintered body (hereinafter, also referred to as “cBN sintered body”). The cBN sintered body is usually composed of cubic boron nitride particles (hereinafter, also referred to as “cBN particles”) and a bonded phase, and its characteristics tend to differ depending on the content ratio of the cBN particles and the composition of the bonded phase.

Therefore, in the field of cutting, the type of cBN sintered body applied to the cutting tool is properly used depending on the material of the work material, the required processing accuracy, and the like.

For example, Japanese Patent Application Laid-Open No. 2017-03028 (Patent Document 1) describes a cubic body containing cubic boron nitride particles as a cBN sintered body that can be used for intermittent cutting of high-hardness steel and a TiC phase as a bonding phase. A crystallization boron nitride sintered body is disclosed.

Japanese Unexamined Patent Publication No. 2017-03028

The cubic boron nitride sintered body of the present disclosure is a cubic boron nitride sintered body comprising 20% by volume or more and 80% by volume or less of cubic boron nitride particles and a bonding phase of 20% by volume or more and 80% by volume or less. And
The binding phase contains first binder particles and second binder particles.
Each of the first binder particles and the second binder particles is at least one selected from the group consisting of titanium, zirconium, hafnium, Group 5 elements, Group 6 elements and aluminum in the periodic table. Contains one compound consisting of one metal element and one or both of zirconium and carbon.
In the first binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of the titanium and the number of atoms of the first metal element is 0.01% or more and less than 10%.
In the second binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of the titanium and the number of atoms of the first metal element is 10% or more and 80% or less. It is a sintered body.

FIG. 1 is an image showing an example of a reflected electron image obtained by observing the cBN sintered body of the present disclosure by SEM. FIG. 2 is an image obtained by reading the reflected electron image of FIG. 1 into image processing software. In FIG. 3, the upper image is a backscattered electron image, and the lower image is a density cross-sectional graph obtained from the backscattered electron image. FIG. 4 is a diagram for explaining a method of defining a black region and a bound phase. FIG. 5 is a diagram for explaining the boundary between the black region and the bound phase. FIG. 6 is an image obtained by binarizing the reflected electron image of FIG. FIG. 7 is an image showing an example of an element mapping image of niobium in the cubic boron nitride sintered body of the present disclosure. FIG. 8 is an image set so as not to display a region in which the Nb content (atomic%) / (Ti content (atomic%) + Nb content (atomic%)) is less than 10% in the element mapping image of FIG. Is. FIG. 9 is an example of a HAADF-STEM (High-angle Anal Dark Field Scanning TEM) image of the cubic boron nitride sintered body of the present disclosure. FIG. 10 is an example of a BF-STEM (Bright Field Scanning TEM) image of the cubic boron nitride sintered body of the present disclosure. FIG. 11 is an example of an element mapping image of the cubic boron nitride sintered body of the present disclosure, and is an image showing the distribution state of boron. FIG. 12 is an example of an element mapping image of the cubic boron nitride sintered body of the present disclosure, and is an image showing the distribution state of titanium. FIG. 13 is an example of a correction element mapping image of the cubic boron nitride sintered body of the present disclosure, and shows the distribution state of niobium (Nb content (atom%) / (Ti content (atom%) + Nb content (atom)). %)) Is an image showing less than 10% cut). FIG. 14 is an example of a HAADF-STEM image of the cubic boron nitride sintered body of the present disclosure. FIG. 15 is an example of a BF-STEM image of the cubic boron nitride sintered body of the present disclosure. FIG. 16 is an example of an element mapping image of the cubic boron nitride sintered body of the present disclosure, and is an image showing a contour diagram. FIG. 17 is an example of a graph showing the result of line analysis. FIG. 18 is an example of a graph showing an X-ray spectrum of the cubic boron nitride sintered body of the present disclosure.

[Issues to be resolved by this disclosure]
Hardened steel with high strength and toughness is used for gears, shafts, and bearing parts of automobiles. In recent years, these parts are required to have mechanical properties that can withstand higher torque. In order to improve the mechanical properties of hardened steel, for example, high-strength hardened steel in which hard particles are dispersed in a hardened steel base has been developed.

High-strength hardened steel has a very high hardness, which makes it very difficult to process with a tool. In particular, in the scene of high-efficiency machining, there is a demand for a tool in which the tool life is unlikely to be shortened due to a defect.

An object of the present disclosure is to provide a cubic boron nitride sintered body capable of extending the life of a tool when used as a material for a tool, particularly even in high-efficiency machining of high-strength hardened steel. ..

[Effect of this disclosure]
When the cubic boron nitride sintered body of the present disclosure is used as a material for a tool, the life of the tool can be extended even in high-efficiency machining of high-strength hardened steel.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described.
(1) The cubic boron nitride sintered body of the present disclosure is
A cubic boron nitride sintered body comprising 20% by volume or more and 80% by volume or less of cubic boron nitride particles and a bonding phase of 20% by volume or more and 80% by volume or less.
The binding phase contains first binder particles and second binder particles.
Each of the first binder particles and the second binder particles is at least one selected from the group consisting of titanium, zirconium, hafnium, Group 5 elements, Group 6 elements and aluminum in the periodic table. Contains one compound consisting of one metal element and one or both of zirconium and carbon.
In the first binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of the titanium and the number of atoms of the first metal element is 0.01% or more and less than 10%.
In the second binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of the titanium and the number of atoms of the first metal element is 10% or more and 80% or less. It is a sintered body.

When the cubic boron nitride sintered body of the present disclosure is used as a material for a tool, the life of the tool can be extended even in high-efficiency machining of high-strength hardened steel.

(2) The number of atoms of the titanium and the first metal element in the direction perpendicular to the interface between the first binder particles and the second binder particles, from the interface to the second binder particles side. When the reference content is measured, in the region where the distance from the interface is within 15 nm, the titanium content tends to decrease as the distance from the interface increases, and the content of the first metal element It is preferable that the content shows an increasing tendency.

According to this, the bonding force at the interface between the first binder particles and the second binder particles is improved, and the fracture resistance of the cubic boron nitride sintered body is improved.

(3) The number of atoms of the titanium and the first metal element in the direction perpendicular to the interface between the first binder particle and the second binder particle, from the interface to the second binder particle side. The reference content is measured linearly with SEM-EDX, and the maximum value of the content of the first metal element is X1, the content of the first metal element with respect to the total content of the titanium and the first metal element. When the content of the first metal element is X2 and the average value of the X1 and the X2 is X3 when the ratio of the above is 10%,
It is preferable that the distance L1 from the position A where the content of the first metal element is X2 to the position E where the content of the first metal element is X3 is 5 nm or more.

According to this, the bonding force at the interface between the first binder particles and the second binder particles is further improved, and the fracture resistance of the cubic boron nitride sintered body is further improved.

(4) The distance L1 is preferably 15 nm or more. According to this, the bonding force at the interface between the first binder particles and the second binder particles is further improved, and the fracture resistance of the cubic boron nitride sintered body is further improved.

(5) The first metal element preferably comprises at least one metal element selected from the group consisting of zirconium, hafnium, niobium, tantalum, molybdenum and tungsten. According to this, the fracture resistance of the cubic boron nitride sintered body is further improved.

(6) The content of the cubic boron nitride particles is preferably 35% by volume or more and 75% by volume or less. According to this, in the cubic boron nitride sintered body, the fracture resistance and the wear resistance are improved in a well-balanced manner.

(7) The ratio of the mass of the second binder particles to the total mass of the first binder particles and the second binder particles is preferably 5% or more and 90% or less, and preferably 10% or more and 50% or less. Is more preferable. According to this, since the lattice constants of the first binder particles and the second binder particles are different, the interface becomes inconsistent, and the strength of the sintered body is improved by the effects of residual stress and lattice defects.

[Details of Embodiments of the present disclosure]
Specific examples of the cubic boron nitride sintered body of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same parts or equivalent parts. Further, the dimensional relationships such as length, width, thickness, and depth are appropriately changed for the purpose of clarifying and simplifying the drawings, and do not necessarily represent the actual dimensional relationships.

In the present specification, the notation in the form of "A to B" means the upper and lower limits of the range (that is, A or more and B or less), and when the unit is not described in A and the unit is described only in B, A The unit of and the unit of B are the same.

When a compound or the like is represented by a chemical formula in the present specification, it shall include all conventionally known atomic ratios when the atomic ratio is not particularly limited, and is not necessarily limited to those in the stoichiometric range. For example, when described as "TiNbCN", the ratio of the number of atoms constituting TiNbCN includes any conventionally known atomic ratio. This also applies to the description of compounds other than "TiNbCN".

[First Embodiment: Cubic Boron Nitride Sintered Body]
The cubic boron nitride sintered body of the present disclosure is a cubic boron nitride sintered body comprising 20% by volume or more and 80% by volume or less of cubic boron nitride particles and a bonded phase of 20% by volume or more and 80% by volume or less. The bonding phase includes the first bonding material particles and the second bonding material particles, and the first bonding material particles and the second bonding material particles are made of titanium, zirconium, hafnium, and the periodic table, respectively. First binder particles containing at least one first metal element selected from the group consisting of Group 5 elements, Group 6 elements and aluminum, and one compound consisting of one or both of nitrogen and carbon. The ratio of the number of atoms of the first metal element to the total number of atoms of the titanium and the number of atoms of the first metal element is 0.01% or more and less than 10%. The ratio of the number of atoms of the first metal element to the total number of the number and the number of atoms of the first metal element is 10% or more and 80% or less.

When the cubic boron nitride sintered body of the present disclosure is used as a material for a tool, the life of the tool can be extended even in high-efficiency machining of high-strength hardened steel. The reason for this is not clear, but it is presumed to be as follows (i) to (iii).

(I) The cubic boron nitride sintered body of the present disclosure contains 20% by volume or more and 80% by volume or less of cubic boron nitride particles having excellent strength and toughness. Therefore, the cBN sintered body can also have excellent strength and toughness. Therefore, a tool using the cubic boron nitride sintered body can have a long tool life even in high-efficiency machining of high-strength hardened steel.

(Ii) In the cubic boron nitride sintered body of the present disclosure, each of the first binder particles and the second binder particles contained in the bonding phase is titanium, zirconium, hafnium, and a Group 5 element in the periodic table. , A compound consisting of at least one first metal element selected from the group consisting of Group 6 elements and aluminum, and one or both of nitrogen and carbon (hereinafter, also referred to as "bonded phase compound"). include. The bonded phase compound is formed by solid-solving a first metal element having an atomic radius different from that of titanium (Ti) in TiN, TiC, and TiCN used in the conventional bonded phase. Therefore, a large amount of lattice defects (dislocations and stacking defects) are introduced into the bonded phase compound.

If lattice defects are present in the bonded phase compound, the energy of crack growth generated during the use of the tool is absorbed by the atomic mismatched portion of the lattice defects, and it is presumed that the propagation of cracks is suppressed. Therefore, a tool using the cubic boron nitride sintered body can have a long tool life even in high-efficiency machining of high-strength hardened steel.

(Iii) In the cubic boron nitride sintered body of the present disclosure, the first binder particles and the second binder particles contained in the bonding phase refer to the total number of atoms of titanium and the number of atoms of the first metal element. The ratio of the number of atoms of the first metal element is different. Therefore, the lattice constants of the first binder particles and the second binder particles are different. When the first binder particles and the second binder particles come into contact with each other in the binding phase, lattice defects in the second binder particles tend to remain.

In the cubic boron nitride sintered body of the present disclosure, since the bonded phase has lattice defects, the propagation of cracks is suppressed in the bonded phase and the fracture resistance is improved. Therefore, a tool using the cubic boron nitride sintered body can have a long tool life even in high-efficiency machining of high-strength hardened steel.

"composition"
The cubic boron nitride sintered body of the present disclosure includes 20% by volume or more and 80% by volume or less of cubic boron nitride particles, and 20% by volume or more and 80% by volume or less of a bonded phase. The cBN sintered body can consist of cBN particles and a bound phase. Further, the cBN sintered body may contain unavoidable impurities due to raw materials, production conditions and the like. In the cubic boron nitride sintered body of the present disclosure, the total content of cBN particles, the content of the bonded phase, and the content of unavoidable impurities is 100% by volume.

In the cubic boron nitride sintered body of the present disclosure, the lower limit of the total content of cBN particles and the content of the bonded phase is 95% by volume or more, 96% by volume or more, 97% by volume or more, 98% by volume or more. , 99% by volume or more. In the cubic boron nitride sintered body of the present disclosure, the upper limit of the total content of cBN particles and the content of the bonded phase can be 100% by volume or less and less than 100% by volume. In the cubic boron nitride sintered body of the present disclosure, the total content of cBN particles and the content of the bonded phase is 95% by volume or more and 100% by volume or less, 96% by volume or more and 100% by volume or less, 97% by volume. 100% by volume or less, 98% by volume or more and 100% by volume or less, 99% by volume or more and 100% by volume or less, 95% by volume or more and less than 100% by volume, 96% by volume or more and less than 100% by volume, 97% by volume or more and less than 100% by volume. , 98% by volume or more and less than 100% by volume, 99% by volume or more and less than 100% by volume.

The content ratio (volume%) of cBN particles and the content ratio (volume%) of the bonded phase in the cBN sintered body are attached to the scanning electron microscope (SEM) (“JSM-7800F” (trade name) manufactured by JEOL Ltd.). Confirmation by performing microstructure observation, elemental analysis, etc. on the cBN sintered body using the energy dispersive X-ray analyzer (EDX) "Octane Elect EDS system" (trade name)). Can be done.

The method for measuring the content ratio (volume%) of cBN particles is as follows. First, an arbitrary position of the cBN sintered body is cut to prepare a sample containing a cross section of the cBN sintered body. A focused ion beam device, a cross-section polisher device, or the like can be used to prepare the cross section. Next, the cross section is observed by SEM at a magnification of 5000 to obtain a reflected electron image. In the backscattered electron image, the region where the cBN particles are present is the black region, and the region where the bound phase is present is the gray region or the white region.

Next, the reflected electron image is binarized using image analysis software (“WinROOF” of Mitani Shoji Co., Ltd.). From the image after the binarization process, the area ratio of the pixels derived from the dark field (pixels derived from the cBN particles) to the area of the measurement field of view is calculated. By regarding the calculated area ratio as a volume%, the content ratio (volume%) of the cBN particles can be obtained.

To obtain the content ratio (volume%) of the coupled phase by calculating the area ratio of the pixels derived from the bright field (pixels derived from the coupled phase) to the area of the measurement visual field from the image after the binarization process. Can be done.
A specific method of binarization processing will be described with reference to FIGS. 1 to 6.

FIG. 1 is an example of a reflected electron image obtained by observing a cBN sintered body with SEM. The reflected electron image is read into image processing software. The read image is shown in FIG. As shown in FIG. 2, an arbitrary line Q1 is drawn in the read image.

The concentration cross-sectional view is measured along the line Q1 and the GRAY value is read. A graph having the line Q1 as the X coordinate and the GRAY value as the Y coordinate (hereinafter, also referred to as a “concentration cross-section graph”) is produced. The backscattered electron image of the cBN sintered body and the density cross-sectional graph of the backscattered electron image are shown in FIG. 3 (the upper image is the backscattered electron image and the lower graph is the density cross-sectional graph). In FIG. 3, the width of the backscattered electron image and the width of the X coordinate of the density cross-sectional graph (23.27 μm) are the same. Therefore, the distance from the left end of the line Q1 in the backscattered electron image to the specific position on the line Q1 is indicated by the value of the X coordinate of the density cross-section graph.

In the reflected electron image of FIG. 3, three black regions where cBN particles are present are arbitrarily selected. The black region is, for example, the portion indicated by the ellipse of reference numeral c in the reflected electron image of FIG.

The GRAY value of each of the three black regions is read from the density cross-sectional graph. The GRAY value of each of the three black regions is the average value of the GRAY values of each of the three portions surrounded by the ellipse of reference numeral c in the density cross-sectional graph of FIG. The average value of the GRAY values of each of the three locations is calculated. The average value is taken as the GRAY value of cBN (hereinafter, also referred to _{as G cbn).}

In the backscattered electron image of FIG. 3, three regions where the bonded phase shown in gray exists are arbitrarily selected. The coupled phase is, for example, the portion indicated by the ellipse of reference numeral d in the reflected electron image of FIG.

The GRAY value of each of the three bonded phases is read from the concentration cross-sectional graph. The GRAY value of each of the three bonded phases is the average value of the GRAY values at each of the three portions surrounded by the ellipse of reference numeral d in the concentration cross-sectional graph of FIG. The average value of the GRAY values of each of the three locations is calculated. The average value is taken as the GRAY value of the binding phase (hereinafter, also referred to _{as G bindr).}

The GRAY value represented by (G _cbn + G _binder ) / 2 is defined as the GRAY value at the interface between the black region (cBN particles) and the bound phase. For example, at a concentration sectional graph of Fig. 4, GRAY value _{G cbn} the black areas (cBN particles) is indicated by the line _{G cbn,} GRAY value _{G binder} of the binder phase is indicated by the line _{G binder, (G cbn + G} binder) The GRAY value indicated by / 2 is indicated by the line G1.

As described above, in the concentration cross-sectional graph, by defining the interface between the black region (cBN particles) and the bound phase, the values of the X coordinate and the Y coordinate at the interface between the black region (cBN particles) and the bound phase are read. Can be done. The interface can be specified arbitrarily. For example, in the reflected electron image at the upper part of FIG. 5, as an example of the portion including the interface, the portion surrounded by the ellipse of the symbol e can be mentioned. In the backscattered electron image of FIG. 5, the interface between the black region (cBN particles) and the bonded phase is, for example, a portion indicated by an ellipse of reference numeral e. In the concentration cross-sectional graph at the bottom of FIG. 5, the interface between the black region (cBN particles) corresponding to the ellipse of the above-mentioned symbol e and the bonded phase is the portion indicated by the arrow e. The tip of the arrow e indicates the position of the intersection of the concentration cross-sectional graph of the GRAY value _{and the line G1 indicating the GRAY value (G cbn} + G _{binder) / 2.} The X-coordinate value of the tip of the arrow e and the Y-coordinate value of the tip of the arrow e correspond to the X-coordinate and Y-coordinate values at the interface between the black region (cBN particle) and the bonding phase.

The binarization process is performed using the values of the X coordinate and the Y coordinate at the interface between the black region (cBN particles) and the bonding phase as threshold values. The image after the binarization process is shown in FIG. In FIG. 6, the area surrounded by the dotted line is the area where the binarization process has been performed. The image after the binarization process includes, in addition to the bright field and the dark field, a white area (a portion whiter than the bright field) corresponding to the area that was white in the image before the binarization process. May be good.

In FIG. 6, the area ratio of the pixels derived from the dark field (pixels derived from the cBN particles) to the area of the measurement field of view is calculated. By regarding the calculated area ratio as a volume%, the content ratio (volume%) of the cBN particles can be obtained.

In FIG. 6, the content ratio (volume%) of the coupled phase can be obtained by calculating the area ratio of the pixels derived from the bright visual field (pixels derived from the coupled phase) to the area of the measurement visual field.

The content ratio of cBN particles in the cBN sintered body is preferably 35% by volume or more and 75% by volume or less, and more preferably 45% by volume or more and 74.5% by volume or less.

The content ratio of the bonded phase in the cBN sintered body is preferably 25% by volume or more and 65% by volume or less, and more preferably 25.5% by volume or more and 55% by volume or less.

<< cBN particles >>
The cBN particles have high hardness, strength and toughness, and serve as a skeleton in the cBN sintered body. The D ₅₀ (average particle size) of the cBN particles is not particularly limited, and can be, for example, 0.1 to 10.0 μm. Generally, the _{smaller the D 50} , the higher the hardness of the cBN sintered body, and the smaller the variation in particle size, the more homogeneous the properties of the cBN sintered body tend to be. _{D 50} of the cBN particles is preferably, for example, to 0.5～4.0Myuemu.

_{D 50} of the cBN particles is determined as follows. First, a sample including a cross section of the cBN sintered body is prepared according to the above method for determining the content ratio of cBN particles, and a backscattered electron image is obtained. Next, the circle-equivalent diameter of each dark field (corresponding to cBN) in the reflected electron image is calculated using image analysis software. It is preferable to calculate the equivalent circle diameter of 100 or more cBN particles by observing 5 or more fields of view.

Next, the diameters corresponding to each circle are arranged in ascending order from the minimum value to the maximum value to obtain the cumulative distribution. Particle diameter at a cumulative area of 50% in the cumulative distribution is _{D 50.} The equivalent circle diameter means the diameter of a circle having the same area as the measured area of the cBN particles.

<< Bonding phase >>
The bonded phase serves to enable cBN particles, which are difficult-to-sinter materials, to be sintered at industrial-level pressure temperatures. Further, since the reactivity with iron is lower than that of cBN, a function of suppressing chemical wear and thermal wear is added in cutting high-strength hardened steel. Further, when the cBN sintered body contains a bonded phase, the wear resistance of the high-strength hardened steel in high-efficiency machining is improved.

In the cBN sintered body of the present disclosure, the bonding phase includes the first binder particles and the second binder particles. Each of the first binder particles and the second binder particles is at least one first metal selected from the group consisting of titanium, zirconium, hafnium, Group 5 elements, Group 6 elements and aluminum of the periodic table. The first compound containing an element and one or both of nitrogen and carbon, with respect to the total number of atoms of the titanium and the number of atoms of the first metal element in the first binder particles. The ratio of the number of atoms of the metal element is 0.01% or more and less than 10%, and the first metal element with respect to the total number of atoms of the titanium and the number of atoms of the first metal element in the second binder particles. The ratio of the number of atoms of is 10% or more and 80% or less. The ratio of the number of atoms of the first metal element to the total number of atoms of titanium and the number of atoms of the first metal element is different between the first binder particle and the second binder particle.

Each of the first binder particles and the second binder particles can consist only of the binding phase compound. Further, each of the first binder particle and the second binder particle can contain other components in addition to the binding phase compound. Examples of elements constituting other components include nickel (Ni), iron (Fe), manganese (Mn), and rhenium (Re).

Here, the Group 5 elements of the periodic table include, for example, vanadium (V), niobium (Nb) and tantalum (Ta). Group 6 elements include, for example, chromium (Cr), molybdenum (Mo) and tungsten (W).

The first metal element preferably comprises at least one metal element selected from the group consisting of zirconium, hafnium, niobium, tantalum, molybdenum and tungsten.

Examples of the compound (nitride) containing titanium, the first metal element, and nitrogen include titanium nitride zirconium (TiZrN), titanium nitride hafnium (TiHfN), titanium nitride vanadium (TiVN), titanium nitride niobium (TiNbN), and titanium nitride. Examples thereof include tantalum (TiTaN), titanium nitride chromium (TiCrN), titanium nitride molybdenum (TiMoN), titanium nitride tungsten (TiWN), and titanium nitride aluminum (TiAlN, Ti ₂ AlN, Ti ₃ AlN).

Examples of the compound (carbide) containing titanium, the first metal element and carbon include titanium carbide zirconium (TiZrC), titanium carbide hafnium (TiHfC), titanium carbide vanadium (TiVC), titanium carbide niobium (TiNbC), and titanium carbide tantalum. (TiTaC), titanium carbide chromium (TiCrC), titanium carbide molybdenum (TiMoC), titanium carbide tungsten (TiWC), titanium carbide aluminum (TiAlC, Ti ₂ AlC, Ti ₃ AlC) and the like.

Examples of the compound (carbonitride) containing titanium, the first metal element, carbon and nitrogen include titanium carbonitride zirconim (TiZrCN), titanium carbonitide hafnium (TiHfCN), titanium carbonitride vanadium (TiVCN), and charcoal. Titanium Nitride Niob (TiNbCN), Titanium Titanium Tantal (TiTaCN), Titanium Titanium Chromium (TiCrCN), Titanium Titanium Molybdenum Molybdenum (TiMoCN), Titanium Titanium Titanium Tungsten (TiWCN), Titanium Titanium Aluminum Nitride (TiAlCN, Ti ₂ AlCN), etc. Can be mentioned.

The binding phase can include a solid solution derived from the above compound. Here, the solid solution derived from the above compound means a state in which two or more kinds of these compounds are dissolved in each other's crystal structure, and means an invasion type solid solution or a substitution type solid solution.

The binding phase can consist only of the first binder particles and the second binder particles. Further, the binding phase may contain other components in addition to the first binder particles and the second binder particles. Examples of elements constituting other components include nickel (Ni), iron (Fe), manganese (Mn), and rhenium (Re).

The overall composition of the bonded phase contained in the cBN sintered body is the energy dispersive X-ray analyzer (EDX) "EDX" attached to the scanning electron microscope (SEM) ("JSM-7800F" (trademark) manufactured by JEOL Ltd.). Structure observation, elemental analysis, etc. using Octane Elect EDS system (trademark), and crystal structure analysis using XRD (X-ray diffraction measurement) (device: "MiniFlex600" (trademark) manufactured by RIGAKU), etc. Can be confirmed by combining.

In the first binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of titanium and the number of atoms of the first metal element is 0.01% or more and less than 10%. When the ratio of the number of atoms of the first metal element is 0.01% or more and less than 10%, the difference in the lattice constants between the first binder particles and the second binder particles becomes large. In this case, when the first binder particles and the second binder particles come into contact with each other, lattice defects in the second binder particles are likely to remain, crack propagation is suppressed in the bonding phase, and a cubic boron nitride sintered body is used. Fracture resistance is significantly improved. Further, when the ratio of the number of atoms of the first metal element is less than 10%, the wear resistance of the first binder particles is improved. Therefore, in the cubic boron nitride sintered body, the fracture resistance and the wear resistance are improved. Is improved in a well-balanced manner.

In the first binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of titanium and the number of atoms of the first metal element is 0.01% or more and less than 10%, and 0.02% or more. 5% or less is preferable, and 0.05% or more and 3% or less is more preferable.

In the second binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of titanium and the number of atoms of the first metal element is 10% or more and 80% or less. When the ratio of the number of atoms of the second metal element is 10% or more, lattice defects in the second binder particles increase, crack propagation is suppressed in the bonding phase, and the fracture resistance of the cubic boron nitride sintered body is suppressed. The sex is significantly improved. When the ratio of the number of atoms of the second metal element is 80% or less, the second binder particles can have excellent strength, and the strength of the cubic boron nitride sintered body is improved.

In the second binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of titanium and the number of atoms of the first metal element is 10% or more and 80% or less, and 11.5% or more and 60%. The following is preferable, and 13% or more and 50% or less is more preferable.

The composition of the first binder particles and the second binder particles, and the total number of atoms of titanium and the number of atoms of the first metal element in each of the first binder particles and the second binder particles. The procedure of the method for measuring the ratio of the number of atoms of one metal element (hereinafter, also referred to as “the ratio of the first metal element”) will be described in (1-1) to (1-5) below.

(1-1) A sample is taken from the cBN sintered body, and the sample is sliced to a thickness of 30 to 100 nm using an argon ion slicer to prepare a section. The section is observed with a transmission electron microscope (hereinafter, also referred to as "TEM") at a magnification of 30,000 and 50,000 to obtain a first image which is a HAADF-STEM image. In the first image, the cBN particles are observed as black and the bound phase and the interface between the particles are observed as white or gray.

(1-2) In the first image, the second image is obtained by positioning so that the region other than the cBN particles (black) is the center of the field of view and observing with the observation magnification changed to 100,000 times. ..

(1-3) Next, element mapping analysis by EDX is performed on the second image to analyze the distribution of titanium, the first metal element, carbon and nitrogen.

(1-4) In the element mapping image of the first metal element, the strongest point (analysis range: about 2 nm) and the lowest point (analysis range: about 2 nm) of the signal of the first metal element are specified, and the region thereof. Confirm that boron is not present in an amount of 15 atomic% or more. If boron is present, it is not considered as the first binder particle and the second binder particle. Here, the point where the signal of the first metal is strongest exists in the second binder particle, and the point where the signal of the first metal is the lowest exists in the first binder particle. Quantitative analysis of titanium, first metal element, carbon and nitrogen is performed at each point.

(1-5) From the results of (1-4) above, the composition at the point where the signal of the first metal is the strongest is specified. The composition corresponds to the composition of the second binder particles. Further, the ratio of the number of atoms of the first metal element (ratio of the first metal element) to the total number of atoms of titanium and the number of atoms of the first metal element at the point where the signal of the first metal is the strongest is calculated. The ratio is calculated in 10 or more fields of view. The average value of the ratio of the first metal element in the 10 visual fields or more corresponds to the ratio of the first metal element in the second binder particles.

From the result of (1-4) above, the composition at the point where the signal of the first metal is the lowest is specified. The composition corresponds to the composition of the first binder particles. Further, the ratio of the number of atoms of the first metal element (ratio of the first metal element) to the total number of atoms of titanium and the number of atoms of the first metal element at the point where the signal of the first metal is the lowest is calculated. The ratio is calculated in 10 or more fields of view. The average value of the ratio of the first metal element in the 10 visual fields or more corresponds to the ratio of the first metal element in the first binder particles.

The cubic boron nitride sintered body of the present disclosure includes titanium and a first metal in a direction perpendicular to the interface between the first binder particles and the second binder particles, from the interface to the second binder particles side. When the atomic number-based content of the element is measured, the titanium content tends to decrease as the distance from the interface increases in the region where the distance from the interface is within 15 nm, and the content of the first metal element It is preferable that the content shows an increasing tendency.

According to this, the bonding force at the interface between the first binder particles and the second binder particles is improved, and the fracture resistance of the cubic boron nitride sintered body is improved.

Here, "a method of measuring the contents of titanium and the first metal element in the direction perpendicular to the interface between the first binder particles and the second binder particles, from the interface to the second binder particles side". (Hereinafter, also referred to as “elemental line analysis”) will be described in (2-1) to (2-9) below.

(2-1) A sample is taken from the cBN sintered body, and the sample is sliced to a thickness of 30 to 100 nm using an ion slicer "EM-09100IS" (trade name) manufactured by JEOL Ltd. to prepare a section. ..

(2-2) The section prepared in (2-1) above was observed with a transmission electron microscope (TEM, "JEM-2100F / Cs" (trade name) manufactured by JEOL Ltd.) at a magnification of 100,000. Element mapping analysis is performed using energy dispersive X-ray spectroscopy (EDX, "EDAX" (trade name) manufactured by AMETEK) incidental to TEM, and an element mapping image is obtained. In the element mapping analysis, the distributions of titanium, each first metal element (zirconium, hafnium, elements contained in Group 5 elements of the periodic table, elements contained in Group 6 elements, aluminum) and boron are analyzed.

(2-3) High-angle scattering annular dark-field scanning transmission electron microscope ("JEM-2100F / Cs" manufactured by JEOL Ltd.) for the same field of view as the element mapping image obtained in (2-2) above. A HAADF-STEM image is obtained using the trade name)).

(2-4) Using a bright-field scanning transmission electron microscope (“JEM-2100F / Cs) manufactured by JEOL Ltd.) for the same field of view as the element mapping image obtained in (2-2) above, Obtain a BF-STEM image.

(2-5) Based on the element mapping image obtained in (2-2) above, the region where the first metal element (hereinafter, also referred to as “M”) is observed (hereinafter, also referred to as “first region”). .) Is specified. Next, in the mapping image of the first metal element (M) obtained above, the region where the M content (atomic%) / (Ti content (atomic%) + M content (atomic%)) is less than 10%. Get an image that is set not to display. In the image, the region where boron is not observed in the boron mapping image obtained in (2-2) above, and the independent mapping region of the first metal element (M) corresponds to the second binder particle. .. The mapping region indicating the second binder particle is defined as a crystal grain, and the boundary of the mapping region is specified as a crystal grain boundary.

(2-6) The elemental mapping image of boron and titanium obtained in (2-2) above, and the M content (atomic%) / (Ti content (atomic%) + M content (atomic%)) are The element mapping image of the first metal element set so as not to display the region less than 10% specifies the region satisfying all of the following (a) to (c) (hereinafter, also referred to as “second region”). do.
(A) Boron is not observed.
(B) Titanium is observed.
(C) No first metal element is observed.

Further, based on the HAADF-STEM image obtained in (2-3) above and the BF-STEM image obtained in (2-4) above, the second binder particles specified in (2-5) above can be obtained. Identify one crystal grain that is adjacent and contains a second region. The crystal grains correspond to the first binder particles. The crystal grain boundaries of the crystal grains are specified by the following method. First, in the mapping image of the first metal element (M) obtained above, a region having an M content (atomic%) / (Ti content (atomic%) + M content (atomic%)) of 10% or more is defined. Get an image that is set not to be displayed. In the image, the mapping region of the first metal element (M) is defined as a crystal grain, and the boundary of the mapping region of the first metal element (M) is specified as a crystal grain boundary.

(2-7) The region containing the second binder particles specified in (2-5) above and the first binder particles specified in (2-6) above was observed by TEM at a magnification of 300,000. Then, element mapping analysis is performed using energy dispersive X-ray spectroscopy (EDX) incidental to TEM to obtain an element mapping image. In the element mapping analysis, the distribution of each first metal element (zirconium, hafnium, the element contained in the group 5 element of the periodic table, the element contained in the group 6 element, aluminum) is analyzed.

(2-8) In the element mapping image obtained in (2-7) above, an contour diagram is taken in the region where the signal of the first metal element is strongly observed, and the first binder particles and the second binder particles are formed. The element line analysis is performed from the interface to the second binder particle side in the direction perpendicular to the interface of the above, and the contents of titanium and the first metal element are measured. Here, the direction perpendicular to the interface means a direction along a straight line intersecting the tangent line in the extending direction of the interface at an angle of 90 ° ± 5 °. The direction perpendicular to the interface is a direction perpendicular to the interface (boundary line) between the first binder particles and the second binder particles in the cross section of the sample and parallel to the cross section. The beam diameter for elemental line analysis shall be 0.3 nm or less, and the scan interval shall be 0.1 to 0.7 nm.

According to the above steps (2-1) to (2-8), titanium and titanium and the second binder particles are formed in the direction perpendicular to the interface between the first binder particles and the second binder particles, from the interface to the second binder particles side. The content of the first metal element can be measured.

The above measurements will be described in detail with reference to FIGS. 7-17 for ease of understanding.

FIG. 7 shows the element mapping obtained when the element mapping analysis was performed on the cBN sintered body in which the first binder particles and the second binder particles contained the composition of TiNbCN, and the distribution of niobium (Nb) was analyzed. It is a statue. In the actual element mapping image, the position where niobium exists shows a dark emission color, but since the element mapping image is displayed in black and white in FIG. 7, the position where niobium exists is displayed as a light color. There is.

The HAADF-STEM image in the same field of view as that of FIG. 7 is shown in FIG. In FIG. 9, the cBN particles are observed as black and the bound phase is observed as white or gray.

A BF-STEM image in the same field of view as that of FIG. 7 is shown in FIG. In FIG. 10, the cBN particles are observed as white and the bound phase is observed as black or gray.

FIG. 11 is an element mapping image obtained when element mapping analysis is performed on the above cBN sintered body and the distribution of boron (B) is analyzed. In the actual element mapping image, the position where boron exists indicates a dark emission color, but in FIG. 11, since the element mapping image is displayed in black and white, the position where boron exists is displayed as a light color. There is.

FIG. 12 is an element mapping image obtained when element mapping analysis is performed on the above cBN sintered body and the distribution of titanium (Ti) is analyzed. In the actual element mapping image, the position where titanium is present shows a dark emission color, but in FIG. 12, since the element mapping image is displayed in black and white, the position where titanium is present is displayed as a light color. There is.

Based on the element mapping image of FIG. 7, the first region where niobium is observed is specified. Further, based on the HAADF-STEM image of FIG. 9 and the BF-STEM image of FIG. 10, one crystal grain containing the first region is specified. The crystal grain boundaries of the crystal grains are specified by the following method. First, in the niobium mapping image obtained above, a region having an Nb content (atomic%) / (Ti content (atomic%) + Nb content (atomic%)) of less than 10% was set not to be displayed. Get an image. In the image, the niobium mapping region is defined as a crystal grain, and the boundary of the niobium mapping region is specified as a crystal grain boundary. The crystal grains correspond to the second binder particles. The region where niobium is observed in FIG. 8 and the region where boron is observed in FIG. 11 do not overlap each other show the second binder particles. The region showing the second binder particles is shown by a dotted line in FIG.

Based on the element mapping images of FIGS. 7, 11 and 12, a second region satisfying all of the following (a) to (c) is specified.
(A) Boron is not observed.
(B) Titanium is observed.
(C) No niobium is observed.

Further, based on the HAADF-STEM image of FIG. 9 and the BF-STEM image of FIG. 10, one crystal grain containing the second region is specified. The crystal grains correspond to the first binder particles. The area surrounded by the solid line in FIG. 9 indicates the first binder particles.

FIG. 13 shows an element mapping image obtained when element mapping analysis was performed on a region including a portion (second binder particle) surrounded by a dotted line in FIG. 9 and the distribution of niobium (Nb) was analyzed. It is a correction element mapping image obtained by cutting the portion of niobium content of 10 atomic% or less. For reference, a HAADF-STEM image in the same field of view as FIG. 13 is shown in FIG. 14, and a BF-STEM image in the same field of view as FIG. 13 is shown in FIG. In FIG. 15, the portion surrounded by the dotted line indicates the second binder particle, and the portion surrounded by the solid line indicates the first binder particle.

In the correction element mapping image of FIG. 13, a contour diagram in a region where the niobium signal is strongly observed is shown in FIG. In FIG. 16, the direction perpendicular to the interface between the first binder particle and the second binder particle (direction along a straight line intersecting the tangent of the interface at an angle of 90 ° ± 5 °) (arrow in FIG. 16). The element line analysis is performed along the direction indicated by a).

FIG. 17 is an example of a graph showing the results of elemental line analysis. In the graph, the horizontal axis (X-axis) indicates the distance (nm) of the lines in FIG. 16, and the vertical axis (Y-axis) indicates the content of titanium and niobium (atomic%).

Next, it was confirmed that "in the region where the distance from the interface is within 15 nm, the titanium content tends to decrease and the content of the first metal element tends to increase as the distance from the interface increases". The specific procedure of the method will be described with reference to FIG. In the following, the case where the first metal element is niobium will be described, but even if the first metal element is another element, it can be confirmed by the same method.

In FIG. 17, the dotted line indicates titanium and the solid line indicates niobium. Further, X1 indicates the maximum value of the niobium content, and X2 indicates the niobium content when the ratio of the niobium content to the total content of titanium and niobium is 10%. X4 indicates the minimum value of the titanium content.

A straight line M connecting A, which is the intersection of the straight line showing the content X2 and the niobium spectrum, and B, which is the intersection of the straight line showing the content X1 and the niobium spectrum, is drawn. The deviation between the straight line M and the spectrum of niobium (hereinafter, also referred to as “Nb spectrum”) is measured at 10 points at equal intervals between A and B (A and B are not included). Here, the deviation between the straight line M and the Nb spectrum means the difference between the niobium content on the Nb spectrum and the niobium content on the straight line M at the same distance. At 7 points or more, when the deviation between the straight line M and the Nb spectrum is within ± 10 atomic%, it is confirmed that “the content of niobium (first metal element) tends to increase”.

A straight line N connecting the point C on the titanium spectrum (hereinafter, also referred to as “Ti spectrum”) at the distance of the intersection A and the intersection D of the straight line indicating the content X4 and the Ti spectrum is drawn. The deviation between the straight line N and the Ti spectrum is measured at 10 points at equal intervals between C and D (C and D are not included). Here, the deviation between the straight line N and the Ti spectrum means the difference between the titanium content on the Ti spectrum and the titanium content on the straight line N at the same distance. At 7 points or more, when the deviation between the straight line N and the Ti spectrum is within ± 10 atomic%, it is confirmed that "the titanium content tends to decrease."

When the above analysis is repeated in the element mapping images for 6 fields and it is confirmed that the above-mentioned increasing tendency and decreasing tendency are shown in 1 field or more, the cBN sintered body is "distance from the interface". In the region of 15 nm or less, the titanium content tends to decrease and the content of the first metal element tends to increase as the distance from the interface increases. "

The cubic boron nitride sintered body of the present disclosure includes titanium and a first metal element in a direction perpendicular to the interface between the first binder particles and the second binder particles, from the interface to the second binder particles side. When the ratio of the content of the first metal element to the total content of X1, titanium and the first metal element is 10%, the maximum value of the content of the first metal element is measured. When the element content is X2, and the average value of X1 and X2 is X3, the position A where the content of the first metal element is X2 to the position E where the content of the first metal element is X3. The distance L1 is preferably 5 nm or more.

According to this, the bonding force at the interface between the first binder particles and the second binder particles is further improved, and the fracture resistance of the cubic boron nitride sintered body is further improved. The distance L1 is preferably 5 nm or more and 300 nm or less, more preferably 15 nm or more and 200 nm or less, and further preferably 30 nm or more and 150 nm or less.

A specific procedure of the method for measuring the distance L1 will be described with reference to FIG. On the Y-axis of FIG. 17, the maximum value of niobium content is indicated by X1, and the niobium content when the ratio of niobium content to the total content of titanium and niobium is 10% is indicated by X2. , The average value of X1 and X2 is indicated by X3. In the Nb spectrum, the position where the niobium content is X2 is indicated by A, and the position where the niobium content is X3 is indicated by E. In the X-axis of FIG. 17, the distance from A to E corresponds to the distance L1.

In the cubic boron nitride sintered body of the present disclosure, the ratio of the mass of the second binder particles to the total mass of the first binder particles and the second binder particles is preferably 5% or more and 90% or less. According to this, the grain boundaries become inconsistent due to the adjacent crystal grains having different lattice constants, the strength is improved by the effects of lattice defects and stress, and the fracture resistance is improved. The ratio of the mass of the second binder particles to the total mass of the first binder particles and the second binder particles is more preferably 10% or more and 70% or less, and further preferably 20% or more and 50% or less.

The ratio of the mass of the second binder particles to the total mass of the first binder particles and the second binder particles can be measured by the X-ray diffraction method. Specific measurement methods will be specifically described in (3-1) to (3-3) below.

(3-1) A cubic boron nitride sintered body is cut with a diamond grindstone electrodeposition wire, and the cut surface is used as an observation surface.

(3-2) An X-ray spectrum of a cut surface of a cubic boron nitride sintered body is obtained using an X-ray diffractometer (“MiniFlex 600” (trade name) manufactured by Rigaku). The conditions of the X-ray diffractometer at this time are as follows.
Characteristic X-ray: Cu-Kα (wavelength 1.54 Å)
Tube voltage: 40kV
Tube current: 15mA
Filter: Multi-layer mirror Optical system: Concentration method X-ray diffraction method: θ-2θ method Scan speed: 4 degrees / minute

(3-3) In the obtained X-ray spectrum, the following peak intensity A and peak intensity B are measured.

Peak intensity A: The peak intensity of the (220) plane of the first binder particles excluding the background from the peak intensity near the diffraction angle 2θ = 60 °.

Peak intensity B: The peak intensity of the (220) plane of the second binder particles excluding the background from the peak intensity near the diffraction angle 2θ = 60 °.

The ratio of the mass of the second binder particle to the total mass of the first binder particle and the second binder particle is obtained by calculating the value of peak intensity B / (peak intensity A + peak intensity B). Specifically, the spectrum is read into XRD analysis software (“PDXL2” manufactured by RIGAKU). It is displayed as spectrum information, and the height corresponding to the (220) plane is calculated as the peak intensity. This peak height is the background. The peak intensity excluding the above is shown in FIG. 18 as an example of the X-ray spectrum of the cubic boron nitride sintered body of the present disclosure.

As shown in FIG. 18, the peaks of the first binder particle and the second binder particle partially overlap each other, and a shoulder may be observed on the high angle side or the low angle side of one peak S. .. In this case, the analysis software recognizes and analyzes the two peaks S1 (peak derived from the (220) plane of the first binder particle) and S2 (peak derived from the (220) plane of the second binder particle). If the analysis software does not automatically recognize the two peaks, the shoulder portion on the low angle side of one peak is regarded as the peak of the second binder particle, and is added by the peak addition function to perform fitting.

[Second Embodiment: Method for Producing Cubic Boron Nitride Sintered Body]
The method for producing the cBN sintered body of the present disclosure will be described. The method for producing the cBN sintered body of the present disclosure is a step of preparing a cubic boron nitride powder (hereinafter, also referred to as "cBN powder"), a first binder powder, and a second binder powder (hereinafter, "" Also referred to as a "preparation step"), and a step of mixing the cBN powder, the first binder powder, and the second binder powder to prepare a mixed powder (hereinafter, also referred to as a "preparation step"). , A step of sintering a mixed powder to obtain a cubic boron nitride sintered body (hereinafter, also referred to as a “sintering step”) can be provided. Hereinafter, each step will be described in detail.

<Preparation process>
First, cBN powder and binder powder are prepared. The cBN powder is a raw material powder of cBN particles contained in the cBN sintered body. The cBN powder is not particularly limited, and known cBN powder can be used. The binder powder is a raw material powder for the bonding phase contained in the cBN sintered body.

The compound contained in the bonded phase of the cBN sintered body of the present disclosure is TiC _x N _y (x ≧ 0, y ≧ 0, x + y> 0) and a first metal having an atomic radius different from that of titanium (Ti). The elements are solid-dissolved, TiM2C _x N _y (x ≧ 0, y ≧ 0, x + y> 0, and M2 indicates a first metal element of 1 or more. The sum of the number of atoms of Ti and the number of atoms of M2. The ratio of the number of atoms of M2 to M2 is 10% or more and 80% or less). Hereinafter, the _{binder having the composition of TiM2C x} N _y is referred to as a main binder.

It is difficult to dissolve metal elements having different atomic radii in titanium by a conventional general method. As a result of diligent studies, the present inventors performed heat treatment of the raw material of the main binder at a high temperature of 1800 ° C. or higher (hereinafter, also referred to as "high temperature heat treatment") to solidify metal elements having different atomic radii into titanium. It has been found that a molten main binder powder can be produced. Furthermore, it has been found that the main binder powder in which metal elements having different atomic radii are solid-solved in titanium can also be produced by subjecting the element powder contained in the main binder to powder thermal plasma treatment. Details of the high temperature heat treatment and the powder thermal plasma treatment will be described below.

(Method using high temperature heat treatment)
An example of a method for producing a main binder powder using high-temperature heat treatment will be described.

Oxide powder of at least one element selected from the group consisting of TiO ₂ powder, zirconium, hafnium, Group 5 element, Group 6 element of the periodic table and aluminum, and carbon (C) powder are mixed. Obtain a mixed powder for the main binder.

Examples of the oxide powder of the first metal element include zirconium oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), vanadium oxide (V ₂ O ₅ ), niobium oxide (Nb ₂ O ₅ ), and tantalum oxide (Ta _2). O ₅ ), chromium oxide (Cr ₂ O ₃ ), molybdenum oxide (MoO ₃ ), and tungsten oxide (WO ₃ ) can be mentioned.

The mixing ratio of TiO ₂ powder, oxide powder of first metal element, and carbon powder is based on atomic%, and titanium: first metal element: carbon = 0.9 to 0.2: 0.1 to 0.8. : It is preferable to mix so as to be 0.1 to 0.9.

The obtained mixed powder for the main binder is heat-treated at 1800 ° C. to 2200 ° C. for 60 minutes in a nitrogen atmosphere. As a result, a single-phase compound having a composition of _{TiM2C x} N _{y is synthesized.} The single-phase compound can be pulverized to a desired particle size by a wet pulverization method to obtain a main binder powder having a composition of _{TiM2C x} N _y.

(Method using powder thermal plasma treatment)
An example of a method for producing a main binder powder using powder thermal plasma treatment will be described.

Titanium (Ti) powder, M (first metal element) powder, and carbon (C) powder are mixed to obtain a mixed powder for a binder. The mixing ratio of titanium (Ti) powder, M (first metal element) powder and carbon (C) powder is a weight ratio. Titanium (Ti) powder: M (first metal element) powder: carbon (C) powder. = 20 to 80: 10 to 80: 1 to 20.

The obtained mixed powder for a binder is treated with a hot powder plasma apparatus (manufactured by JEOL, TP-4002NPS). For example, a mixed powder for a main binder is set in the chamber of a hot powder plasma apparatus, and N ₂ gas is introduced at a flow rate of 30 L / min under the condition of an output of 6 kW for processing. Thus, it is possible to obtain a main binder powder having a composition of TiM2C _x N _y.

In order to sinter the cBN powder and the above-mentioned main binder powder, _{it is preferable to use Ti 2} AlN and / or Ti ₂ AlC as an auxiliary binder. By using the sub-bonding material, the bonding between the cBN particles and the main bonding material is promoted. Further, by mixing and sintering the main binder powder and the sub-bond material powder, a part of the first metal element (M2) contained in the main binder powder and the sub-bond material powder are separated from TiM1C _x. N _y (x ≧ 0, y ≧ 0, x + y> 0, and M1 represents the same first metal element as M2. The ratio of the number of M1 atoms to the total number of Ti atoms and M1 atoms. Is more than 0.01% and less than 10%). The _{compound having a composition of TiM1C x} N _y constitutes the first binder particles in the cBN sintered body.

Hereinafter, an example of a method for producing _{Ti 2} AlC powder as the auxiliary binder powder will be described. Titanium (Ti) powder, aluminum (Al) powder, and TiC powder are mixed in a weight ratio of titanium (Ti) powder: aluminum (Al) powder: TiC powder = 37: 22: 41 for a secondary binder. Obtain a mixed powder.

The obtained mixed powder for an auxiliary binder is heat-treated at 1500 ° C. for 60 minutes in an argon atmosphere. As a result, a single-phase compound having a composition of _{Ti 2 AlC is synthesized.} The single-phase compound can be pulverized to a desired particle size by a wet pulverization method to obtain an accessory binder powder having a composition of _{Ti 2 AlC.}

<Preparation process>
This step is a step of mixing the cBN powder and the binder powder to prepare a mixed powder. Here, the binder powder can include a main binder powder and a sub-bonder powder.

The mixing ratio of the cBN powder and the binder powder is such that the ratio of the cBN powder in the mixed powder is 20% by volume or more and 80% by volume or less, and the ratio of the binder powder is 20% by volume or more and 80% by volume or less. adjust. When the main binder powder and the sub-bond material powder are used as the binder powder, the mixing ratio of the main binder powder and the sub-bond material powder is such that the sub-bond material decomposes into _{TiM1C x} N _{y and Al after sintering.} Assuming that the weight ratio is TiM1C _x N _y : TiM2C _x N _y = 10 to 95: 90 to 5, the mixture is calculated and blended.

The mixing ratio of the cBN powder in the mixed powder and the binder powder is substantially the same as the ratio of the cBN particles in the cBN sintered body obtained by sintering the mixed powder and the bonding phase. .. Therefore, by adjusting the mixing ratio of the cBN powder in the mixed powder and the binder powder, the ratio of the cBN particles and the bonding phase in the cBN sintered body can be set in a desired range.

The method of mixing the cBN powder and the binder powder is not particularly limited, but from the viewpoint of efficient and homogeneous mixing, ball mill mixing, bead mill mixing, planet mill mixing, jet mill mixing and the like can be used. Each mixing method may be wet or dry.

The cBN powder and the binder powder are preferably mixed by wet ball mill mixing using ethanol, acetone or the like as a solvent. After mixing, the solvent is removed by natural drying. Then, by heat treatment, impurities such as moisture adsorbed on the surface are volatilized to clean the surface. As a result, a mixed powder is prepared.

<Sintering process>
This step is a step of sintering the mixed powder to obtain a cBN sintered body. In this step, the mixed powder is exposed to high temperature and high pressure conditions and sintered to produce a cBN sintered body.

First, in order to remove water and impurities in the mixed powder, a high temperature (for example, 900 ° C. or higher) heat treatment (hereinafter, also referred to as “degassing treatment”) is performed under vacuum. The mixed powder after the degassing treatment is filled in a capsule for ultra-high pressure sintering, and vacuum-sealed using a metal as a sealing material under vacuum.

Next, the vacuum-sealed mixed powder is sintered using an ultra-high temperature and high pressure device. The sintering conditions are, for example, 5.5 to 8 GPa and 1200 ° C. or higher and lower than 1800 ° C., preferably 5 to 60 minutes. In particular, from the viewpoint of the balance between cost and sintering performance, it is preferably 6 to 7 GPa and 1400 to 1600 ° C. for 10 to 30 minutes. As a result, a cBN sintered body is produced.

[Third Embodiment: Tool]
The cubic boron nitride sintered body of the present disclosure can be used as a material for tools. The tool can include the above cBN sintered body as a base material. Further, the tool may have a coating film on the surface of the cBN sintered body as the base material.

The shape and use of the tool are not particularly limited. For example, drills, end mills, replaceable cutting tips for drills, replaceable cutting tips for end mills, replaceable cutting tips for milling, replaceable cutting tips for turning, metal saws, gear cutting tools, reamers, taps, cranks. Examples include a tip for pin milling of a shaft.

Further, the tool according to the present embodiment is not limited to a tool in which the entire tool is made of a cBN sintered body, and a tool in which only a part of the tool (particularly a cutting edge portion (cutting edge portion) etc.) is made of a cBN sintered body. Also includes. For example, the tool according to the present embodiment also includes a tool in which only the cutting edge portion of a substrate (support) made of cemented carbide or the like is composed of a cBN sintered body. In this case, the cutting edge portion shall be regarded as a tool in terms of wording. In other words, the cBN sintered body is referred to as a tool even when the cBN sintered body occupies only a part of the tool.

According to the tool according to the present embodiment, since the cBN sintered body is included, the life can be extended.

The present embodiment will be described in more detail with reference to Examples. However, these embodiments do not limit the present embodiment.

<Sample 1>
(Preparation process)
A cBN powder (average particle size: 3 μm), a main binder powder, and an auxiliary binder powder were prepared. The main binder powder was prepared by a method using high temperature heat treatment. Specifically, the TiO ₂ powder, the Nb ₂ O ₅ powder, and the carbon (C) powder are mixed in a weight ratio of 57.19: 16.79: 26.02, and the mixed powder for the main binder is mixed. Got The mixed powder for the main binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiNbCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain a TiNbCN powder.

The TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) were mixed to prepare a binder powder. The mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) was adjusted so that the ratio of aluminum (Al) in the binder powder was 1% by weight.

(Preparation process)
The cBN powder and the binder powder were mixed in a volume ratio of cBN powder: binder powder = 65:35, and uniformly mixed by a ball mill to obtain a mixed powder.

(Sintering process)
The obtained mixed powder was filled in a container made of Ta in contact with a cemented carbide disk of WC-6% Co, vacuum-sealed, and 6.5 GPa, using a belt-type ultrahigh-pressure high-temperature generator. Sintered at 1500 ° C. for 15 minutes. As a result, a cBN sintered body was produced.

<Sample 2>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) was adjusted so that the ratio of aluminum (Al) in the binder powder was 2% by weight. A cBN sintered body was prepared by the same manufacturing method as that of sample 1 except for the above.

<Sample 3>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) was adjusted so that the ratio of aluminum (Al) in the binder powder was 4% by weight. A cBN sintered body was prepared by the same manufacturing method as that of sample 1 except for the above.

<Sample 4>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) was adjusted so that the ratio of aluminum (Al) in the binder powder was 7% by weight. A cBN sintered body was prepared by the same manufacturing method as that of sample 1 except for the above.

<Sample 5>
In the preparatory step, the TiO ₂ powder, the Nb ₂ O ₅ powder, and the carbon (C) powder are mixed in a weight ratio of 43.83: 31.25: 24.92, and the TiNbCN powder (main binder powder) is mixed. ) And Ti ₂ AlC powder (secondary binder powder) were adjusted so that the ratio of aluminum (Al) in the binder powder was 4% by weight, but cBN was produced by the same manufacturing method as sample 1. A sintered body was produced.

<Sample 6>
In the preparatory step, the TiO ₂ powder, the Nb ₂ O ₅ powder, and the carbon (C) powder are mixed in a weight ratio of 28.66: 47.67: 23.67, and the TiNbCN powder (main binder powder) is mixed. ) And Ti ₂ AlC powder (secondary binder powder) were adjusted so that the ratio of aluminum (Al) in the binder powder was 4% by weight, but cBN was produced by the same manufacturing method as sample 1. A sintered body was produced.

<Sample 7>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) is adjusted so that the ratio of aluminum (Al) in the binder powder is 4% by weight. A cBN sintered body was prepared by the same manufacturing method as that of Sample 1 except that the sintering temperature was set to 1750 ° C. in the sintering step.

<Sample 8>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) is adjusted so that the ratio of aluminum (Al) in the binder powder is 4% by weight. A cBN sintered body was prepared by the same manufacturing method as that of Sample 1 except that the sintering temperature was set to 1250 ° C. in the sintering step.

<Sample 9>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) is adjusted so that the ratio of aluminum (Al) in the binder powder is 0.5% by weight. A cBN sintered body was prepared by the same manufacturing method as that of Sample 1 except for the adjustment.

<Sample 10>
In the preparatory step, the TiO ₂ powder, the Nb ₂ O ₅ powder, and the carbon (C) powder are mixed in a weight ratio of 7.49: 70.58: 21: 93, and the TiNbCN powder (main binder powder) is mixed. ) And Ti ₂ AlC powder (secondary binder powder) were adjusted so that the ratio of aluminum (Al) in the binder powder was 4% by weight, but cBN was produced by the same manufacturing method as sample 1. A sintered body was produced.

<Sample 11>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TiZrCN powder was used instead of TiNbCN powder as the main binder powder.

The TiZrCN powder was prepared by the following method. The TiO ₂ powder, the ZrO ₂ powder, and the carbon (C) powder were mixed in a weight ratio of 58.35: 15.88: 25.77 to obtain a mixed powder for a binder. The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiZrCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain TiZrCN powder.

<Sample 12>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TimoCN powder was used instead of TiNbCN powder as the main binder powder.

The TimoCN powder was prepared by the following method. The TiO ₂ powder, the MoO ₃ powder, and the carbon (C) powder were mixed in a weight ratio of 55.99: 17.80: 26.21 to obtain a mixed powder for a binder. The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TimoCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain a TimoCN powder.

<Sample 13>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TiHfCN powder was used instead of TiNbCN powder as the main binder powder.

The TiHfCN powder was prepared by the following method. The TiO ₂ powder, the HfO ₂ powder, and the carbon (C) powder were mixed in a weight ratio of 52.45: 24.38: 23.17 to obtain a mixed powder for a binder. The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiHfCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain TiHfCN powder.

<Sample 14>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TiTaCN powder was used instead of TiNbCN powder as the main binder powder.

The TiTaCN powder was prepared by the following method. The TiO ₂ powder, the Ta ₂ O ₅ powder, and the carbon (C) powder were mixed in a weight ratio of 51.467: 25.116: 23.417 to obtain a mixed powder for a binder. The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiTaCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain TiTaCN powder.

<Sample 15>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TiWCN powder was used instead of TiNbCN powder as the main binder powder.

The TiWCN powder was prepared by the following method. The TiO ₂ powder, the WO ₃ powder, and the carbon (C) powder were mixed in a weight ratio of 51.53: 26.39: 22.08 to obtain a mixed powder for a binder. The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiWCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain a TiWCN powder.

<Sample 16>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TiVCN powder was used instead of TiNbCN powder as the main binder powder.

The TiVCN powder was prepared by the following method. TiO ₂ powder, V ₂ O ₅ powder (manufactured by high-purity chemicals), and carbon (C) powder are mixed in a weight ratio of 63.62: 11.65: 24.73, and a mixed powder for a binder is used. Got The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiVCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain a TiVCN powder.

<Sample 17>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TiCrCN powder was used instead of TiNbCN powder as the main binder powder.

The TiCrCN powder was prepared by the following method. TiO ₂ powder, Cr ₂ O ₃ powder (manufactured by high-purity chemicals) and carbon (C) powder are mixed in a weight ratio of 62.64: 10.52: 26.84, and a mixed powder for a binder is mixed. Got The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiCrCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain TiCrCN powder.

<Sample 18>
A cBN sintered body was prepared by the same production method as that of Sample 1 except that TiAlCN powder was used instead of TiNbCN powder as the main binder powder.

The TiAlCN powder was prepared by the following method. The TiO ₂ powder, the Al ₂ O ₃ powder, and the carbon (C) powder were mixed in a weight ratio of 64.89: 7.31: 27.80 to obtain a mixed powder for a binder. The mixed powder for a binder was heat-treated at 2100 ° C. for 60 minutes in a nitrogen atmosphere to synthesize a single-phase compound having a TiAlCN composition. The single-phase compound was pulverized to a particle size of 0.5 μm by a wet pulverization method to obtain TiAlCN powder.

<Sample 19>
In the preparation step, a cBN sintered body was prepared by the same manufacturing method as in Sample 3 except that the cBN powder and the binder powder were mixed in a volume ratio of cBN powder: binder powder = 50:50.

<Sample 20>
In the preparation step, a cBN sintered body was prepared by the same manufacturing method as that of Sample 3 except that the cBN powder and the binder powder were mixed in a volume ratio of cBN powder: binder powder = 80:20.

<Sample 21>
In the preparation step, a cBN sintered body was prepared by the same manufacturing method as in Sample 3 except that the cBN powder and the binder powder were mixed in a volume ratio of cBN powder: binder powder = 10:90.

<Sample 22>
In the preparation step, a cBN sintered body was prepared by the same manufacturing method as that of Sample 3 except that the cBN powder and the binder powder were mixed in a volume ratio of cBN powder: binder powder = 90:10.

<Sample 23>
In the preparation of the binder powder in the preparation step _{, instead of mixing the TiNbCN powder (main binder powder) and the Ti 2} AlC powder (secondary binder powder), the TiNbCN powder (main binder powder) and the Al powder (main binder powder) A cBN sintered body was prepared by the same manufacturing method as in Sample 3 except that the binder powder was prepared by mixing with "Minalco 900F" (trade name) manufactured by Minarco. The mixing ratio of TiNbCN powder (main binder powder) and Al powder was adjusted so that the ratio of aluminum (Al) in the binder powder was 4% by weight.

<Sample 24>
In the preparation step, a cBN sintered body was prepared by the same manufacturing method as in Sample 3 except that the cBN powder and the binder powder were mixed in a volume ratio of cBN powder: binder powder = 20:80.

<Sample 25>
Same as sample 3 except that in the preparation step, TiO ₂ powder, Nb ₂ O ₅ powder, and carbon (C) powder were mixed in a weight ratio of 62.10: 11.48: 26.42. A cBN sintered body was produced by the manufacturing method.

<Sample 26>
Same as sample 3 except that in the preparation step, TiO ₂ powder, Nb ₂ O ₅ powder, and carbon (C) powder were mixed at a weight ratio of 10.17: 67.68: 22.15. A cBN sintered body was produced by the manufacturing method.

<Sample 27>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) was adjusted so that the ratio of aluminum (Al) in the binder powder was 13% by weight. A cBN sintered body was prepared by the same manufacturing method as that of sample 1 except for the above.

<Sample 28>
In the preparatory step, the mixing ratio of TiNbCN powder (main binder powder) and Ti ₂ AlC powder (secondary binder powder) was adjusted so that the ratio of aluminum (Al) in the binder powder was 17% by weight. A cBN sintered body was prepared by the same manufacturing method as that of sample 1 except for the above.

[evaluation]
<< Content ratio of cBN particles and bound phase >>
For the cBN sintered bodies of Samples 1 to 28, the content ratios (volume%) of the cBN particles and the bound phase were measured using an energy dispersive X-ray analyzer (EDX) attached to a scanning electron microscope (SEM). .. Since the specific measurement method is described in the first embodiment, the description thereof will not be repeated. The results are shown in the columns of "cBN particles (volume%)" and "bonding phase (volume%)" in Tables 1 to 3.

As a result of the measurement, in all the samples, the content ratios of the cBN particles and the bound phase in the cBN sintered body are the cBN powder and the bound in the total (volume%) (that is, the mixed powder) of the cBN powder and the bound phase powder. It was confirmed that the content ratio of each of the wood powders was maintained.

<< Composition of 1st binder particle and 2nd binder particle, ratio of 1st metal element >>
For the cBN sintered bodies of Samples 1 to 28, the composition of the first binder particles and the second binder particles, and the content of the constituent elements (number of atoms) in each of the first binder particles and the second binder particles. Reference) was measured using TEM-EDX. Since the specific measurement method is described in the first embodiment, the description thereof will not be repeated.

_{As a result of the measurement, TiB 2} , AlN and Al ₂ O ₃ were confirmed in each sample together with the first binder particles and the second binder particles. The specific binder compositions of the first binder particles and the second binder particles in each sample are described in the "Composition" column of "First binder particles" in Tables 1 to 3, respectively, and "Second binder". Shown in the "Composition" column of "Particles".

Further, in each of the first binder particle and the second binder particle, the ratio of the number of titanium atoms and the ratio of the number of atoms of the first metal element to the total number of atoms of titanium and the number of atoms of the first metal element are calculated. Calculated. The results are shown in the "Ti ratio (%)" column, "M1 ratio (%)" column of "1st binder particle", and "Ti ratio (%)" of "2nd binder particle" in Tables 1 to 3. It is shown in the column, "M2 ratio (%)" column.

《Elemental line analysis》
Regarding the cBN sintered body of Samples 1 to 28, titanium and the first metal element in the direction perpendicular to the interface between the first binder particles and the second binder particles, from the interface to the second binder particles side. Content was measured by elemental line analysis. Since the specific measurement method is described in the first embodiment, the description thereof will not be repeated.

As a result of the element line analysis, the cBN sintered bodies of Samples 1 to 22 and Samples 24 to 28 were found in the direction perpendicular to the interface between the first binder particles and the second binder particles, from the interface to the first. 2 When the contents of titanium and the first metal element were measured on the binder particle side, titanium showed a decreasing tendency as the distance from the interface increased in the region where the distance from the interface was within 15 nm, and the first It was confirmed that the metal element showed an increasing tendency. Sample 23, binder phase second binder particles _are formed from TiB 2, AlN and _Al 2 _{O 3,} since the first binder particles is not present, the interface between the first coupling material particles and the second binder particles The distribution of the composition in was not measurable.

From the results of the element line analysis, the contents of titanium and the first metal element were measured in the direction perpendicular to the interface between the first binder particle and the second binder particle, and from the interface to the second binder particle side. Then, the maximum value of the content of the first metal element is X1, and the content of the first metal element when the ratio of the content of the first metal element to the total content of titanium and the first metal element is 10% is set. When the average value of X2, X1 and X2 is X3, the distance L1 from the position A where the content of the first metal element is X2 to the position E where the content of the first metal element is X3 is measured. .. Since the specific measurement method is described in the first embodiment, the description thereof will not be repeated. The results are shown in the "L1 (nm)" column of Tables 1 to 3.

<< Ratio of the mass of the second binder particle to the total mass of the first binder particle and the second binder particle >>
The ratio of the mass of the second binder particles to the total mass of the first binder particles and the second binder particles was measured by the X-ray diffraction method. Since the specific measurement method is described in the first embodiment, the description thereof will not be repeated. The results are shown in the "Mass ratio of second binder particles" column of Tables 1 to 3.

《Cutting test》
A cutting tool (tool model number: DNGA150412, cutting edge treatment S01225) was prepared using the cBN sintered body of Samples 1 to 28 as the cutting edge. Using this, a cutting test was carried out under the following cutting conditions.
Cutting speed: 180 m / min.
Feed rate: 0.2 mm / rev.
Notch: 0.17 mm
Coolant: DRY
Cutting method: Intermittent cutting Lathe: LB400 (manufactured by Okuma Corporation)
Work material: Hardened steel (SKD11, hardness 58HRC, intermittent cutting of V-groove on the outer circumference)
The above cutting conditions correspond to high-efficiency machining of high-strength hardened steel.

The cutting edge was observed every 0.1 km of cutting distance, and the size of chipping of the cutting edge was measured. The size of chipping of the cutting edge is defined as the size of chipping in the main component force direction based on the position of the cutting edge ridge line before cutting. The cutting distance at the time when the chipping size of the cutting edge became 0.1 mm or more was measured. The longer the cutting distance, the longer the life of the cutting tool. The results are shown in the "Distance (km)" column of Tables 1 to 3.

<< Consideration >>
The cBN sintered bodies of Samples 1 to 8, Samples 11 to 20, and Samples 24 to 28 correspond to Examples. It was confirmed that the cBN of these samples showed excellent tool life even in high-efficiency machining of high-strength hardened steel when used as a tool material.

The cBN sintered body of Sample 9 has a ratio of the number of atoms of the first metal element in the first binder particles of 0.001%, which corresponds to a comparative example. When the cBN sintered body of Sample 9 was used as a material for a tool, the tool life was shorter than that in the above-mentioned example.

The cBN sintered body of Sample 10 has a ratio of the number of atoms of the first metal element in the second binder particles of 85%, which corresponds to a comparative example. When the cBN sintered body of Sample 10 was used as a material for a tool, the tool life was shorter than that in the above-mentioned example.

The cBN sintered body of Sample 21 has a content ratio of cBN particles of 10% by volume, which corresponds to a comparative example. When the cBN sintered body of Sample 21 was used as a material for a tool, the tool life was shorter than that in the above-mentioned example.

The cBN sintered body of sample 22 has a content ratio of cBN particles of 90% by volume, which corresponds to a comparative example. The cBN sintered body of Sample 22 had a shorter tool life than the above-mentioned example when used as a material for a tool.

The cBN sintered body of Sample 23 does not contain the first binder particles and corresponds to a comparative example. The cBN sintered body of Sample 23 had a shorter tool life than the above-mentioned example when used as a material for a tool.

Although the embodiments and examples of the present disclosure have been described as described above, it is planned from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined or variously modified.
The embodiments and examples disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the embodiments and examples described above, and is intended to include meaning equivalent to the scope of claims and all modifications within the scope.

1 1st binder particle, 2 2nd binder particle

Claims (7)

A cubic boron nitride sintered body comprising 20% by volume or more and 80% by volume or less of cubic boron nitride particles and a bonding phase of 20% by volume or more and 80% by volume or less.
The binding phase contains first binder particles and second binder particles.
Each of the first binder particles and the second binder particles is at least one selected from the group consisting of titanium, zirconium, hafnium, Group 5 elements, Group 6 elements and aluminum in the periodic table. Contains one compound consisting of one metal element and one or both of zirconium and carbon.
In the first binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of the titanium and the number of atoms of the first metal element is 0.01% or more and less than 10%.
In the second binder particles, the ratio of the number of atoms of the first metal element to the total number of atoms of the titanium and the number of atoms of the first metal element is 10% or more and 80% or less. Sintered body. Atomic number reference of the titanium and the first metal element is contained from the interface to the second binder particle side in a direction perpendicular to the interface between the first binder particle and the second binder particle. When the amount was measured, in the region where the distance from the interface was within 15 nm, the titanium content tended to decrease as the distance from the interface increased, and the content of the first metal element increased. The cubic boron nitride sintered body according to claim 1, which shows an increasing tendency. Atomic number reference of the titanium and the first metal element is contained from the interface to the second binder particle side in a direction perpendicular to the interface between the first binder particle and the second binder particle. The amount is measured linearly with SEM-EDX, and the maximum value of the content of the first metal element is X1, and the ratio of the content of the first metal element to the total content of the titanium and the first metal element is When the content of the first metal element at 10% is X2, and the average value of the X1 and the X2 is X3,
According to claim 1 or 2, the distance L1 from the position A where the content of the first metal element is X2 to the position E where the content of the first metal element is X3 is 5 nm or more. The described cubic boron nitride sintered body. The cubic boron nitride sintered body according to claim 3, wherein the distance L1 is 15 nm or more. The cubic crystal according to any one of claims 1 to 4, wherein the first metal element is composed of at least one metal element selected from the group consisting of zirconium, hafnium, niobium, tantalum, molybdenum and tungsten. Boron nitride sintered body. The cubic boron nitride sintered body according to any one of claims 1 to 5, wherein the content of the cubic boron nitride particles is 35% by volume or more and 75% by volume or less. Any one of claims 1 to 6, wherein the ratio of the mass of the second binder particles to the total mass of the first binder particles and the second binder particles is 5% or more and 90% or less. The cubic boron nitride sintered body described in 1.

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