JP6082650B2 - Cubic boron nitride sintered body and coated cubic boron nitride sintered body - Google Patents

Description

  The present invention relates to a cubic boron nitride sintered body and a coated cubic boron nitride sintered body. Specifically, the present invention relates to a cubic boron nitride-containing sintered body and a coated cubic boron nitride sintered body that are optimal as cutting tools and wear-resistant tools.

  Cubic boron nitride has characteristics that it has hardness next to diamond, excellent thermal conductivity, and low affinity with iron. Cubic boron nitride sintered bodies made of cubic boron nitride and a binder phase of metal or ceramic have been applied to cutting tools, wear-resistant tools, and the like. As prior art of cubic boron nitride sintered bodies, cubic boron nitride, aluminum oxide, aluminum nitride and / or aluminum boride, titanium carbide, titanium nitride and / or titanium carbonitride, titanium boride, There is a cubic boron nitride sintered body made of (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 7-82031

  In the tendency for cutting conditions to become stricter than before in order to increase machining efficiency, it has been required to extend the tool life. However, the cubic boron nitride sintered body described in Patent Document 1 has not been able to adequately meet these requirements. The present invention solves such a problem, and improves the fracture resistance and toughness without reducing the wear resistance, and increases the tool life of the cutting tool and the wear-resistant tool. An object is to provide a coated cubic boron nitride sintered body.

  The inventors have conducted research on a cubic boron nitride sintered body, and in order to increase the toughness of the cubic boron nitride sintered body, it is important to suppress propagation of the generated cracks, For this purpose, the inventors have obtained the knowledge that it is effective to have many grain boundaries in the binder phase of the cubic boron nitride sintered body, and have completed the present invention.

  The present inventors have conducted research on a cubic boron nitride sintered body. In order to improve the wear resistance of a cubic boron nitride sintered body tool, harder particles are used for forming a binder phase. Obtaining knowledge that it is effective to use the raw material powder, the present invention has been completed.

The gist of the present invention is as follows.
(1) It consists of cubic boron nitride, a binder phase and unavoidable impurities, and the binder phase is at least one selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo and W and Ti. The compound solid solution compound has a NaCl structure, and the half width of the (200) plane diffraction line of the compound solid solution compound obtained by X-ray diffraction measurement of 2θ / θ method using Cu-Kα rays is Cubic boron nitride sintered body of 0.60 ° or more and 0.90 ° or less.
(2) The peak of the (200) plane diffraction line of the composite solid solution compound obtained when the 2θ measurement range is 30 ° to 90 ° by X-ray diffraction measurement of 2θ / θ method using Cu-Kα rays. to the height I _1, the highest peak height ratio of I ₂ in compounds and metal diffraction lines included in the binding phase and incidental impurities other than the composite solid solution compound (I 2 _{/ I 1)} is 1.0 or less The cubic boron nitride sintered body according to (1).
(3) Atoms of Ti and M (wherein M represents at least one element selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo and W) contained in the entire binder phase The ratio is Ti: M = (0.5-0.98) :( 0.5-0.02) (however, the sum of the atomic ratio of Ti and the atomic ratio of M is 1) (1 ) Or (2) cubic boron nitride sintered body.
(4) The binder phase includes any one of (1) to (3), which includes a composite solid solution compound, at least one aluminum compound of aluminum oxide, aluminum nitride, and aluminum boride, and titanium boride. Cubic boron nitride sintered body.
(5) The composite solid solution compound is (Ti _1-x M _x ) (C _1-y N _y ) (where x represents the atomic ratio of M to the total of Ti and M, and y represents the ratio of C and N The atomic ratio of N to the total is shown, and x and y are 0.02 ≦ x ≦ 0.5 and 0 ≦ y ≦ 1, respectively, where 0 <y <1 when the composite solid solution compound is a composite solid solution carbonitride ) is a is) a composite solid solution compounds represented (1) to any one of cubic boron nitride sintered body (4).
(6) The cubic boron nitride sintered body has a cubic boron nitride: 10 to 90% by volume with respect to the entire cubic boron nitride sintered body, a binder phase and inevitable impurities: the entire cubic boron nitride sintered body. The cubic boron nitride sintered body according to any one of (1) to (5), which is 10 to 90% by volume with respect to the total, and the total of these is 100% by volume.
(7) A coated cubic boron nitride sintered body in which a coating layer is formed on the surface of the cubic boron nitride sintered body according to any one of (1) to (6).

  The cubic boron nitride sintered body of the present invention comprises a binder phase, cubic boron nitride and unavoidable impurities. When the cubic boron nitride is less than 10% by volume with respect to the entire cubic boron nitride sintered body and the binder phase and inevitable impurities are more than 90% by volume with respect to the entire cubic boron nitride sintered body, On the other hand, the deficiency is reduced, while the cubic boron nitride is more than 90% by volume with respect to the entire cubic boron nitride sintered body, and the binder phase is 10% by volume with respect to the entire cubic boron nitride sintered body. Since the wear resistance is reduced when the ratio is less than 10%, the cubic boron nitride sintered body of the present invention has 10 to 90% by volume of cubic boron nitride and cubic boron nitride based on the entire cubic boron nitride sintered body. A cubic boron nitride sintered body composed of 10 to 90% by volume of binder phase and inevitable impurities with respect to the entire sintered body, and the total of these is 100% by volume is preferable.

The binder phase of the present invention contains at least one selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, and W and a composite solid solution compound of Ti. As the composite solid solution compound of the present invention, for example, at least one selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo and W, Ti composite solid solution carbide, composite solid solution nitride, composite solid solution Carbonitride, composite solid solution carbonitride, composite solid solution carbonitride, composite solid solution carbonitride, composite solid solution carbonate, composite solid solution nitride oxide, composite solid solution carbonitride oxide, composite solid solution carbonitride, composite solid solution nitrogen Mention may be made of compounds with at least one selected from the group consisting of boric oxides, composite solid solution carbonitrides and their mutual solid solutions.
Among them, (Ti _1-x M _x ) (C _1-y N _y ) (where M is at least one selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, and W) X represents the atomic ratio of M to the sum of Ti and M, y represents the atomic ratio of N to the sum of C and N, and x and y are 0.02 ≦ x ≦ 0. 5, 0 ≦ y ≦ 1 (however, when the composite solid solution compound is a composite solid solution carbonitride, 0 <y <1)) , since the wear resistance is excellent, preferable.
The binder phase of the present invention may be composed only of a composite solid solution compound, but in addition to the composite solid solution compound, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Fe, Co, Ni Carbides, nitrides, borides, silicides, carbonitrides, carbonitrides, carbonitrides, borohydrides, nitrided nitrides, borosilicates, carbonitrides, borosilicates, boron nitrides It is also preferable to contain at least one of borocarbonitrides and their mutual solid solutions, Fe, Co, Ni, Cr, Mo, W and alloys thereof. Examples of the binder phase other than the composite solid solution compound include aluminum compounds such as aluminum oxide, aluminum nitride, and aluminum boride, and titanium boride.

  As the raw material powder, a composite solid solution compound powder can be added to obtain the binder phase of the present invention. In conventional cubic boron nitride sintered bodies, Ti compounds such as Ti (C, N), TiC, and TiN have been used as the binder phase. The composite solid solution compound of the present invention is at least one kind of M selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, and W in a Ti compound such as Ti (C, N), TiC, and TiN. Is a solid solution, and is harder than the Ti compound. It can be confirmed by X-ray diffraction measurement that the cubic boron nitride sintered body contains the composite solid solution compound. In addition, the solid solution amount of M in the composite solid solution compound in the cubic boron nitride sintered body is estimated by the atomic ratio of Ti and M obtained by energy dispersive X-ray spectroscopy (EDS) for the entire binder phase. I can do it. When the atomic ratio of M to the total of Ti and M contained in the whole binder phase is less than 0.02, the effect of hardening the composite solid solution compound due to solid solution of M cannot be sufficiently obtained. Moreover, when the atomic ratio of M with respect to the sum of Ti and M exceeds 0.5, the thermal conductivity of the binder phase tends to decrease. From this, the atomic ratio of Ti and M contained in the whole binder phase is Ti: M = (0.5-0.98) :( 0.5-0.02) (however, the atomic ratio of Ti and M It is more preferable that the total is 1).

  When the half-value width of the (200) plane diffraction line of the composite solid solution compound contained in the cubic boron nitride sintered body of the present invention is 0.60 ° or more, the average particle size of the composite solid solution compound becomes fine, and the cubic crystal The mechanical strength of the boron nitride sintered body is improved. However, when the half-value width of the (200) plane diffraction line of the composite solid solution compound is larger than 0.90 °, the average particle size of the composite solid solution compound becomes too fine and the thermal conductivity is lowered. Therefore, the half width of the (200) plane diffraction line of the composite solid solution compound is set to 0.60 ° or more and 0.90 ° or less.

  The Bragg angle 2θ and half width of the (200) plane diffraction line of the composite solid solution compound can be measured using a commercially available X-ray diffractometer. For example, using an X-ray diffractometer RINT TTRIII manufactured by Rigaku Corporation, X-ray diffraction measurement of a 2θ / θ concentration method optical system using Cu-Kα rays is performed: output: 50 kV, 250 mA, incident side solar slit: 5 ° Divergence longitudinal slit: 1/2 °, divergence longitudinal restriction slit: 10 mm, scattering slit 2/3 °, light receiving side solar slit: 5 °, light receiving slit: 0.15 mm, BENT monochromator, light receiving monochrome slit: 0.8 mm Sampling width: 0.02 °, scan speed: 0.1 ° / min, 2θ measurement range: 40-46 °, Bragg angle 2θ and half value for (200) plane diffraction line of composite solid solution compound The width can be measured. The (200) plane diffraction line of the compound solid solution compound is a PDF card No. of Powder Diffraction File PDF-2 Release 2004 (hereinafter referred to as PDF card) of International Center for Diffraction Data. No. 32-1383 TiC (200) plane diffraction line and PDF card no. It appears between the (200) plane diffraction lines of TiN described in 38-1420. When obtaining the Bragg angle 2θ and half width of the (200) plane diffraction line of the composite solid solution compound from the X-ray diffraction pattern, analysis software attached to the X-ray diffraction apparatus may be used. In the analysis software, background processing and Kα2 peak removal are performed using cubic approximation, profile fitting is performed using the Pearson-VII function, peak positions are obtained by the peak top method, Bragg angle 2θ and half width Is derived.

The peak height of the (200) plane diffraction line of the composite solid solution compound obtained when the measurement range of the Bragg angle 2θ is 30 ° to 90 ° by X-ray diffraction measurement of 2θ / θ method using Cu-Kα rays. When the highest peak height ratio of I ₂ in the diffraction line of the compound or a metal contained in the binder phase other than the complex compound (I 2 _{/ I 1)} is 1.0 or less with respect to I ₁ is, the binder phase The ratio of the composite solid solution compound to occupy increases, and the wear resistance is improved. Among them, the peak height ratio (I ₂ / I ₁ ) is more preferably 0.7 or less, and the peak height ratio (I ₂ / I ₁ ) is more preferably 0.4 or less. . When obtaining the peak height I ₁ and the peak height I _{2 from} the X-ray diffraction pattern, analysis software attached to the X-ray diffractometer may be used. In the analysis software, background processing and Kα2 peak removal are performed using cubic approximation, profile fitting is performed using the Pearson-VII function, peak positions are obtained by the peak top method, and peak height I ₁ and peak are calculated. Height I ₂ is derived.

  When the cubic boron nitride sintered body of the present invention includes a binder phase composed of at least one aluminum compound among aluminum oxide, aluminum nitride, and aluminum boride, a composite solid solution compound, and titanium boride, The crystal boron nitride sintered body has a good balance between wear resistance and toughness, and when used as a tool, the effect of further extending the tool life is obtained, which is preferable. This is due to the following reason. When at least one aluminum compound among aluminum oxide, aluminum nitride, and aluminum boride is included, toughness is improved. When a composite solid solution compound is included, wear resistance is improved. When titanium boride is included, toughness is improved.

  Examples of impurities inevitably contained in the cubic boron nitride sintered body of the present invention include lithium contained in raw material powders and the like. Since the total amount of inevitable impurities can be usually suppressed to 1% by mass or less with respect to the entire cubic boron nitride sintered body, the characteristic value of the present invention is not affected. In the present invention, in addition to cubic boron nitride, a binder phase, and unavoidable impurities, in addition to the cubic boron nitride sintered body of the present invention, other than inevitable impurities can be said. You may contain a small amount of ingredients.

  The coating layer of the present invention is not particularly limited as long as it is used as a coating layer of a coated tool, but is selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Y, Al, and Si. Selected from the group consisting of a metal comprising at least one metal element selected from the group consisting of a metal element and a compound comprising at least one metal element selected from the group consisting of carbon, nitrogen, oxygen and boron. It is more preferable that it is at least one single layer or laminated layer since the wear resistance is improved. Specific examples include TiN, TiC, TiCN, TiAlN, TiSiN, and CrAlN. The coating layer is preferably either a single layer or a laminate of two or more layers, and preferably has an alternate laminate structure in which two or more layers having an average layer thickness of 5 to 500 nm having different compositions are alternately laminated. The total layer thickness of the entire coating layer is an average layer thickness, and if it is less than 0.5 μm, the wear resistance is lowered, and if it exceeds 20 μm, the chipping resistance is lowered. Therefore, it is preferably 0.5 to 20 μm. .

The cubic boron nitride sintered body of the present invention is an average in which the atomic ratio of M to the total of titanium and M is 0.02 to 0.5, and the atomic ratio of carbon to the total of carbon and nitrogen is 0 to 1. A composite solid solution compound powder having a particle size of 0.01 to 0.1 μm, an aluminum powder, a cubic boron nitride powder, and paraffin are mixed, and the resulting mixture is molded, and the pressure is 1.33 × 10 ⁻¹ Pa. After vacuum heat treatment is performed at a temperature of 400 to 500 ° C. in the following vacuum to remove organic substances such as paraffin, and further, heating is performed at 700 to 1000 ° C. under the same vacuum pressure to perform preliminary sintering. It is obtained by putting in an ultra-high pressure and high temperature generator and sintering under conditions of pressure 5-8 GPa and temperature 1400-1600 ° C. The average particle size of the raw material powder was measured by the Fisher method (Fisher Sub-Sieve Sizer (FSSS)) described in the American Society for Testing and Materials (ASTM) Standard B330.

  Since the cubic boron nitride sintered body and the coated cubic boron nitride sintered body of the present invention are excellent in wear resistance, fracture resistance, and toughness, they are preferably applied to cutting tools and wear resistant tools. More preferably, it is applied to a tool.

(Effect of the invention)
The cubic boron nitride sintered body and the coated cubic boron nitride sintered body of the present invention are excellent in wear resistance, fracture resistance and toughness. Therefore, when the cubic boron nitride sintered body and the coated cubic boron nitride sintered body of the present invention are used as a cutting tool or a wear-resistant tool, an effect that the tool life can be extended is obtained.

Example 1
A cubic boron nitride (cBN) powder having an average particle size of 2 μm, a composite solid solution compound powder having the composition and average particle size shown in Table 1 or a Ti (C _0.5 N _0.5 ) powder, and an Al powder having an average particle size of 2 μm. And blended into the composition shown in Table 1. The average particle size of the raw material powder was measured by the Fisher method (Fisher Sub-Sieve Sizer (FSSS)) described in the American Society for Testing and Materials (ASTM) Standard B330. The blended raw material powder was placed in a ball mill cylinder together with a cemented carbide ball, a hexane solvent, and paraffin, and ball mill mixed. The mixed powder obtained by mixing and pulverizing with a ball mill was compacted. The mixed powder molded body is put into a vacuum heating furnace, the inside of the furnace is evacuated to a pressure of 1.33 × 10 ⁻³ Pa or less, deparaffinized at a temperature of 450 ° C., then heated up, pressure Preliminary sintering was performed at a temperature of 850 ° C. in a vacuum of 1.33 × 10 ⁻³ Pa or less. The obtained temporary sintered body is sealed in a metal capsule, and the metal capsule is put into an ultra-high pressure and high temperature generator, and sintered under the conditions of pressure 5.5 GPa, temperature 1500 ° C., and holding time 30 minutes. A comparative cubic boron nitride sintered body was obtained.

The cubic boron nitride sintered body thus obtained was subjected to SEM observation, EDS measurement, wavelength dispersive X-ray spectroscopy (WDS) measurement, and X-ray diffraction measurement to examine the composition of the cubic boron nitride sintered body. It was. Further, the cross-sectional structure of the cubic boron nitride sintered body was observed with an SEM, and the volume% of cubic boron nitride (cBN) and the volume% of the binder phase were measured. The composition of the composite solid solution compound of the binder phase was confirmed as follows. When X-ray diffraction measurement is performed on Inventions 1 to 12 and Comparative Product 1, between the diffraction line of TiC (PDF card No. 32-1383) and the diffraction line of TiN (PDF card No. 38-1420), A diffraction line of a compound having a NaCl structure was observed. Further, as shown in Table 3, the peak height I ₂ of the diffraction lines of other bonded phases is 0.2 or less with respect to the peak height I ₁ of the (200) plane diffraction line of this NaCl structure compound. Therefore, it can be assumed that most of the bonded phase is a compound having this NaCl structure. On the other hand, from the results of EDS measurement, Ti and M are contained in the binder phases of Inventions 1 to 12 and Comparative Product 1 in the ratios shown in Table 4. As shown in Table 4, the ratio of Ti and M contained in the binder phase was the same as the ratio of Ti and M of the composite solid solution compound powder of the raw material powder. Therefore, when X-ray diffraction measurement was performed on the composite solid solution compound powder of the raw material powder, a NaCl between the Bragg angle 2θ of the diffraction line of the composite solid solution compound powder of the raw material powder and the diffraction lines of TiC and TiN was obtained. The Bragg angle 2θ of the diffraction line of the compound having the structure coincided. From these results, the composition of the compound having the NaCl structure was set to the same composition as the composite solid solution compound powder of the raw material powder. When the X-ray diffraction measurement was performed for the comparative product 2, a diffraction line having a NaCl structure was observed between the TiC diffraction line and the TiN diffraction line. From the results of the EDS measurement and the WDS measurement, as shown in Table 4, the binder phase of the comparative product 2 contained Ti. Was subjected to _Ti (C _{0.5 N 0.5)} X-ray diffraction measurement of the powder of the raw material powder, the raw material powder _Ti (C _{0.5 N 0.5)} and the Bragg angle 2θ of the diffraction lines of the powder, NaCl Since the Bragg angle 2θ of the diffraction line of the compound having the structure coincided with that of the compound having the structure, the composition of the compound having the NaCl structure was Ti (C _0.5 N _0.5 ). These results are shown in Table 2.

In order to measure the half width of the diffraction line and the peak height of the obtained cubic boron nitride sintered body, an output: 50 kV, 250 mA, incident, using a Rigaku Corporation X-ray diffractometer RINT TTRIII. Side solar slit: 5 °, divergence longitudinal slit: 1/2 °, divergence longitudinal restriction slit: 10 mm, scattering slit 2/3 °, light receiving side solar slit: 5 °, light receiving slit: 0.15 mm, BENT monochromator, light receiving Monochrome slit: 0.8 mm, sampling width: 0.02 °, scan speed: 0.1 ° / min, 2θ measurement range: 2θ / θ concentration method using Cu-Kα ray under the conditions of 30 ° to 90 ° An X-ray diffraction measurement of the optical system was performed. From the obtained X-ray diffraction pattern, the diffraction line of TiC (PDF card No. 32-1383) and TiN (PDF card No. 38-1420) are used by using MRD XRD analysis software JADE6 attached to the X-ray diffractometer. The half-value width and the peak height I ₁ were determined for the (200) plane diffraction lines of the NaCl-structured composite solid solution compound and Ti (C _0.5 N _0.5 ) between the two diffraction lines. The highest peak among the diffraction lines of the combined phase and inevitable impurities excluding the composite solid solution compound and Ti (C _0.5 N _0.5 ) using the analysis software JADE6 attached to the XRDX line diffractometer manufactured by MDI It obtains the height _{I 2,} was determined the ratio of the peak of the _{I 2} height for _{I 1 (I 2 / I 1} ). These values are shown in Table 3. In addition, in the XRD analysis software JADE6 manufactured by MDI attached to the X-ray diffractometer, the background processing and Kα2 peak removal are performed using cubic approximation, the profile fitting is performed using the Pearson-VII function, and then the peak top method is used. Further, the peak position is obtained, and the half width and peak height of each diffraction line are derived.

  Next, the ratio (atomic ratio) of Ti and M contained in the binder phase of the cubic boron nitride sintered body was examined by performing EDS measurement. The results are shown in Table 4.

Next, with reference Indentation fracture method (median type), it was measured with Vickers hardness Hv of the applied load 98N and fracture toughness value K _1C of cubic boron nitride sintered body. These results are shown in Table 5.

  Next, the inventive product and the comparative product were processed into ISO standard CNGA120408 insert-shaped cutting tools. The obtained cutting tools were subjected to the following cutting tests (1) and (2). The results are shown in Table 6.

Cutting test (1)
Peripheral continuous dry cutting (turning),
Work material: SCM415H (HRC 60.9-61.7),
Work material shape: Cylinder φ63mm × L200mm,
Cutting speed: 250 m / min,
Cutting depth: 0.25mm,
Feed: 0.1 mm / rev,
Tool life: Cutting time to reach VBc = 0.15 mm or cutting time to breakage.

Cutting test (2)
Peripheral weak intermittent dry cutting (turning),
Work material: SCM435H (HRC 60.9-61.7),
Work material shape: Cylindrical φ 48 mm x L 200 mm with two 90 ° V grooves,
Cutting speed: 200 m / min,
Cutting depth: 0.25mm,
Feed: 0.1 mm / rev,
Tool life: Cutting time to reach VBc = 0.15 mm or cutting time to breakage.

The inventive cubic boron nitride sintered body has higher hardness Hv and fracture toughness value K _1C than the comparative cubic boron nitride sintered body, and as a result, wear resistance and fracture resistance during cutting. The tool life is longer than that of the comparative product in continuous cutting and weak interrupted cutting.

(Example 2)
A cubic boron nitride (cBN) powder having an average particle diameter of 2 μm, a composite solid solution compound powder having the composition and average particle diameter shown in Table 7 or a Ti (C _0.5 N _0.5 ) powder, and an Al powder having an average particle diameter of 2 μm. And blended into the blending composition shown in Table 7. The average particle size of the raw material powder was measured by the Fisher method (Fisher Sub-Sieve Sizer (FSSS)) described in the American Society for Testing and Materials (ASTM) Standard B330. The blended raw material powder was placed in a ball mill cylinder together with a cemented carbide ball, a hexane solvent, and paraffin, and ball mill mixed. The mixed powder obtained by mixing and pulverizing with a ball mill was compacted. The mixed powder molded body is put into a vacuum heating furnace, the inside of the furnace is evacuated to a pressure of 1.33 × 10 ⁻³ Pa or less, deparaffinized at a temperature of 450 ° C., then heated up, pressure Preliminary sintering was performed at a temperature of 850 ° C. in a vacuum of 1.33 × 10 ⁻³ Pa or less. The obtained temporary sintered body is sealed in a metal capsule, and the metal capsule is put into an ultra-high pressure and high temperature generator, and sintered under the conditions of pressure 5.5 GPa, temperature 1500 ° C., and holding time 30 minutes. A comparative cubic boron nitride sintered body was obtained.

The cubic boron nitride sintered body thus obtained was subjected to SEM observation, EDS measurement, WDS measurement, and X-ray diffraction measurement to examine the composition of the sintered body. Further, the cross-sectional structure of the cubic boron nitride sintered body was observed with an SEM, and the volume% of cubic boron nitride (cBN) and the volume% of the binder phase were measured. The composition of the composite solid solution compound of the binder phase was confirmed as follows. When X-ray diffraction measurement was performed on Invention Products 13 to 24 and Comparative Product 3, between the diffraction line of TiC (PDF card No. 32-1383) and the diffraction line of TiN (PDF card No. 38-1420), A diffraction line of a compound having a NaCl structure was observed. Further, as shown in Table 9, the peak height I ₂ of the diffraction lines of other bonded phases is 0.18 or less with respect to the peak height I ₁ of the (200) plane diffraction line of this NaCl structure compound. Therefore, it can be presumed that most of the bonded phase is a compound having this NaCl structure. On the other hand, from the results of EDS measurement, Ti and M are contained in the binder phases of Invention Products 13 to 24 and Comparative Product 3 in the proportions shown in Table 10. As shown in Table 10, the ratio of Ti and M contained in the binder phase was the same as the ratio of Ti and M in the composite solid solution compound powder of the raw material powder. Therefore, when X-ray diffraction measurement was performed on the composite solid solution compound powder of the raw material powder, a NaCl between the Bragg angle 2θ of the diffraction line of the composite solid solution compound powder of the raw material powder and the diffraction lines of TiC and TiN was obtained. The Bragg angle 2θ of the diffraction line of the compound having the structure coincided. From these results, the composition of the compound having the NaCl structure was set to the same composition as the composite solid solution compound powder of the raw material powder. When the X-ray diffraction measurement was performed on the comparative product 4, a diffraction line having a NaCl structure was observed between the TiC diffraction line and the TiN diffraction line. From the results of EDS measurement and WDS measurement, as shown in Table 10, the binder phase of the comparative product 4 contained Ti. Was subjected to _Ti (C _{0.5 N 0.5)} X-ray diffraction measurement of the powder of the raw material powder, the raw material powder _Ti (C _{0.5 N 0.5)} and the Bragg angle 2θ of the diffraction lines of the powder, NaCl Since the Bragg angle 2θ of the diffraction line of the compound having the structure coincided with that of the compound having the structure, the composition of the compound having the NaCl structure was Ti (C _0.5 N _0.5 ). These results are shown in Table 8.

For the obtained cubic boron nitride sintered body, in order to measure the half width of the diffraction line and the peak height, an X-ray diffractometer RINT TTRIII manufactured by Rigaku Corporation was used under the same measurement conditions as in the examples. X-ray diffraction measurement was performed. From the obtained X-ray diffraction pattern, the diffraction line of TiC (PDF card No. 32-1383) and TiN (PDF card) were used in the same manner as in Example 1 using the XRD analysis software JADE6 manufactured by MDI. No. 38-1420) The half-value width and the peak height I ₁ of the complex solid solution compound of NaCl structure and the (200) plane diffraction line of Ti (C _0.5 N _0.5 ) between the diffraction line of No. 38-1420) And asked. Similarly, the highest peak height I ₂ in the diffraction lines of the bonded phase and inevitable impurities excluding the composite solid solution compound and Ti (C _0.5 N _0.5 ) is obtained, and the peak height of I ₂ with respect to I ₁ The ratio (I ₂ / I ₁ ) was determined. These values are shown in Table 9.

  Next, the ratio (atomic ratio) of Ti and M contained in the binder phase of the cubic boron nitride sintered body was examined by performing EDS measurement. The results are shown in Table 10.

Next, with reference Indentation fracture method (median type), it was measured with Vickers hardness Hv of the applied load 98N and fracture toughness value K _1C of cubic boron nitride sintered body. These results are shown in Table 11.

  Next, the inventive product and the comparative product were processed into ISO standard CNGA120408 insert-shaped cutting tools. The obtained cutting tool was subjected to the following cutting tests (3) and (4). The results are shown in Table 12.

Cutting test (3)
Peripheral continuous dry cutting (turning),
Work material: SCM415H (HRC 60.9-61.7),
Work material shape: Cylinder φ63mm × L200mm,
Cutting speed: 250 m / min,
Cutting depth: 0.15 mm,
Feed: 0.1 mm / rev,
Tool life: Cutting time to reach VBc = 0.15 mm or cutting time to breakage.

Cutting test (4)
Peripheral weak intermittent dry cutting (turning),
Work material: SCM435H (HRC 60.9-61.7),
Work material shape: Cylindrical φ 48 mm x L 200 mm with two 90 ° V grooves,
Cutting speed: 100 m / min,
Cutting depth: 0.15 mm,
Feed: 0.1 mm / rev,
Tool life: Cutting time to reach VBc = 0.15 mm or cutting time to breakage.

The inventive cubic boron nitride sintered body has higher hardness Hv and fracture toughness value K _1C than the comparative cubic boron nitride sintered body, and as a result, wear resistance and fracture resistance during cutting. The tool life is longer than conventional products in continuous cutting and weak interrupted cutting.

(Example 3)
A cubic boron nitride (cBN) powder having an average particle diameter of 2 μm, a composite solid solution compound powder or Ti (C _0.5 N _0.5 ) powder having the composition and average particle diameter shown in Table 13, and an Al powder having an average particle diameter of 2 μm. And blended into the blending composition shown in Table 13. The average particle size of the raw material powder was measured by the Fisher method (Fisher Sub-Sieve Sizer (FSSS)) described in the American Society for Testing and Materials (ASTM) Standard B330. The blended raw material powder was placed in a ball mill cylinder together with a cemented carbide ball, a hexane solvent, and paraffin, and ball mill mixed. The mixed powder obtained by mixing and pulverizing with a ball mill was compacted. The mixed powder molded body is put into a vacuum heating furnace, the inside of the furnace is evacuated to a pressure of 1.33 × 10 ⁻³ Pa or less, deparaffinized at a temperature of 450 ° C., then heated up, pressure Preliminary sintering was performed at a temperature of 850 ° C. in a vacuum of 1.33 × 10 ⁻³ Pa or less. The obtained temporary sintered body is sealed in a metal capsule, and the metal capsule is put into an ultra-high pressure and high temperature generator, and sintered under the conditions of pressure 5.5 GPa, temperature 1500 ° C., and holding time 30 minutes. A comparative cubic boron nitride sintered body was obtained.

The cubic boron nitride sintered body thus obtained was subjected to SEM observation, EDS measurement, WDS measurement, and X-ray diffraction measurement to examine the composition of the cubic boron nitride sintered body. Further, the cross-sectional structure of the cubic boron nitride sintered body was observed with an SEM, and the volume% of cubic boron nitride (cBN) and the volume% of the binder phase were measured. The composition of the composite solid solution compound of the binder phase was confirmed as follows. When X-ray diffraction measurement is performed on the inventive products 25 to 36 and the comparative product 5, between the diffraction lines of TiC (PDF card No. 32-1383) and the diffraction lines of TiN (PDF card No. 38-1420), A diffraction line of a compound having a NaCl structure was observed. Further, as shown in Table 15, the peak height I ₂ of the diffraction lines of other bonded phases is 0.34 or less with respect to the peak height I ₁ of the (200) plane diffraction line of this NaCl structure compound. Therefore, it can be assumed that most of the bonded phase is a compound having this NaCl structure. On the other hand, from the results of EDS measurement, Ti and M are contained in the binder phases of Invention Products 25 to 36 and Comparative Product 5 in the ratios shown in Table 16. As shown in Table 16, the ratio of Ti and M contained in the binder phase was the same as the ratio of Ti and M of the composite solid solution compound powder of the raw material powder. Therefore, when X-ray diffraction measurement was performed on the composite solid solution compound powder of the raw material powder, a NaCl between the Bragg angle 2θ of the diffraction line of the composite solid solution compound powder of the raw material powder and the diffraction lines of TiC and TiN was obtained. The Bragg angle 2θ of the diffraction line of the compound having the structure coincided. From these results, the composition of the compound having the NaCl structure was set to the same composition as the composite solid solution compound powder of the raw material powder. When the X-ray diffraction measurement was performed on the comparative product 6, a diffraction line having a NaCl structure was observed between the TiC diffraction line and the TiN diffraction line. From the results of the EDS measurement and the WDS measurement, as shown in Table 16, the binder phase of the comparative product 6 contained Ti. Was subjected to _Ti (C _{0.5 N 0.5)} X-ray diffraction measurement of the powder of the raw material powder, the raw material powder _Ti (C _{0.5 N 0.5)} and the Bragg angle 2θ of the diffraction lines of the powder, NaCl Since the Bragg angle 2θ of the diffraction line of the compound having the structure coincided with that of the compound having the structure, the composition of the compound having the NaCl structure was Ti (C _0.5 N _0.5 ). These results are shown in Table 14.

About the obtained cubic boron nitride sintered compact, in order to measure the half-value width and peak height of a diffraction line, the same measurement conditions as Example 1 were used using Rigaku Co., Ltd. X-ray diffraction apparatus RINT TTRIII. The X-ray diffraction measurement was performed. From the obtained X-ray diffraction pattern, the diffraction line of TiC (PDF card No. 32-1383) and TiN (PDF) were used in the same manner as in Example 1 using the XRD analysis software JADE6 manufactured by MDI. Half-width and peak height I for the complex solid solution compound of NaCl structure and the (200) plane diffraction line of Ti (C _0.5 N _0.5 ) between the diffraction line of Card No. 38-1420) ₁ was requested. Similarly, the highest peak height I ₂ in the diffraction lines of the bonded phase and inevitable impurities excluding the composite solid solution compound and Ti (C _0.5 N _0.5 ) is obtained, and the peak height of I ₂ with respect to I ₁ The ratio (I ₂ / I ₁ ) was determined. These values are shown in Table 15.

  Next, the ratio (atomic ratio) of Ti and M contained in the binder phase of the cubic boron nitride sintered body was examined by performing EDS measurement. The results are shown in Table 16.

Next, the fracture toughness value K _{1C of} the cubic boron nitride sintered body and the Vickers hardness Hv with an applied load of 98 N were measured using an indentation fracture method (median type). These results are shown in Table 17.

  Next, the inventive product and the comparative product were processed into ISO standard CNGA120408 insert-shaped cutting tools. The obtained cutting tools were subjected to the following cutting tests (5) and (6). The results are shown in Table 18.

Cutting test (5)
Peripheral continuous dry cutting (turning),
Work material: SCM415H (HRC 60.9-61.7),
Work material shape: Cylinder φ63mm × L200mm,
Cutting speed: 150 m / min,
Cutting depth: 0.25mm,
Feed: 0.1 mm / rev,
Tool life: Cutting time to reach VBc = 0.15 mm or cutting time to breakage.

Cutting test (6)
Peripheral weak intermittent dry cutting (turning),
Work material: SCM435H (HRC 60.9-61.7),
Work material shape: Cylindrical φ 48 mm x L 200 mm with two 90 ° V grooves,
Cutting speed: 150 m / min,
Cutting depth: 0.25mm,
Feed: 0.1 mm / rev,
Evaluation: Cutting time until reaching VBc = 0.15 mm or cutting until defect.

The inventive cubic boron nitride sintered body has higher hardness Hv and fracture toughness value K _1C than the comparative cubic boron nitride sintered body, and as a result, wear resistance and fracture resistance during cutting. The tool life is longer than conventional products in continuous cutting and weak interrupted cutting.

Example 4
The surface of Invention 1 of Example 1 was coated using a PVD apparatus. Invented product 37 in which the surface of a cubic boron nitride sintered body is coated with a TiN layer having an average layer thickness of 3 μm. Invented product in which the surface of a cubic boron nitride sintered body is coated with a TiAlN layer having an average layer thickness of 3 μm. 38. The inventive products 37 and 38 were subjected to the same cutting tests (1) and (2) as in Example 1. The results are shown in Table 19.

  The inventive products 37 and 38 coated with the coating layer were able to further extend the tool life compared to the inventive product 1 not coated with the coating layer.

  The cubic boron nitride sintered body and the coated cubic boron nitride sintered body of the present invention are excellent in wear resistance, fracture resistance, and toughness, and particularly when used as a cutting tool or wear resistant tool. Since it can be extended, industrial applicability is high.

Claims (6)

A composite solid solution carbonitride of Ti and at least one selected from the group consisting of Zr, Hf, Nb , Cr, Mo, and W, comprising cubic boron nitride, a binder phase, and inevitable impurities The composite solid solution carbonitride has a NaCl structure, and the half width of the (200) plane diffraction line of the composite solid solution carbonitride obtained by the X-ray diffraction measurement of 2θ / θ method using Cu-Kα ray is 0.60 ° more than 0.90 ° Ri der below,
The atomic ratio of Ti and M (wherein M represents at least one element selected from the group consisting of Zr, Hf, Nb, Cr, Mo and W) contained in the entire binder phase is Ti: M = (0.5-0.9) :( 0.5 to 0.1) (the total of the atomic ratios and M atomic ratio of Ti becomes 1) cubic boron nitride sintered body Ru der. Peak height of (200) plane diffraction line of composite solid solution carbonitride obtained by X-ray diffraction measurement of 2θ / θ method using Cu-Kα ray, when 2θ measurement range is 30 ° to 90 ° composite solid solution carbonitride other nitrides of binder phase and inevitably contained impurities compounds and metal tallest peak peak height ratio of the height I ₂ in the diffraction line for the I ₁ is (I 2 _{/ I 1)} 1 The cubic boron nitride sintered body according to claim 1, which is 0.0 or less. The cubic boron nitride according to claim 1 or 2 , wherein the binder phase contains a composite solid solution carbonitride, at least one aluminum compound of aluminum oxide, aluminum nitride, and aluminum boride, and titanium boride. Sintered body. The composite solid solution carbonitride is (Ti _1-x M _x ) (C _1-y N _y ) (where M is at least one selected from the group consisting of Zr, Hf, Nb, Ta, Cr, Mo and W) X represents the atomic ratio of M to the sum of Ti and M, y represents the atomic ratio of N to the sum of C and N, and x and y are 0.02 ≦ x ≦, respectively. The cubic boron nitride sintered body according to any one of claims 1 to 3 , which is a composite solid solution carbonitride expressed as 0.5, 0 < y < 1. The cubic boron nitride sintered body has a cubic boron nitride: 10 to 90% by volume with respect to the entire cubic boron nitride sintered body, and a binder phase and inevitable impurities: with respect to the entire cubic boron nitride sintered body. The cubic boron nitride sintered body according to any one of claims 1 to 4 , comprising 10 to 90% by volume, and a total of these is 100% by volume. A coated cubic boron nitride sintered body in which a coating layer is formed on the surface of the cubic boron nitride sintered body according to any one of claims 1 to 5 .