Appeal No. 2003-1525
Application 09/462,876
THE INVENTION
The appellants claim a cutting tool comprising a specified
cubic boron nitride sintered compact, and a process for making
the compact. Claims 1 and 9 are illustrative:
1. A cutting tool comprising, as an edge part, a cubic
boron nitride sintered compact containing cubic boron nitride
having an average grain diameter of at most 1 µm, in which the
cubic boron nitride sintered compact has, at the said edge part,
an I(200), /I(111) of (220) diffraction intensity (I(200) to (111)
diffraction intensity I(111) ratio of at least 0.05 in X-ray
diffraction of arbitrary direction and impurities are
substantially not contained in the grain boundaries, wherein the
traverse rupture strength of the said cubic boron nitride
sintered compact is at least 80 kgf/mm2 by a three point bending
measurement at a temperature between 20°C and 1000°C and the
thermal conductivity of the cubic boron nitride sintered compact,
at the said edge part, is 250 to 1000 W/m@K.
9. A process for the production of a sintered compact for a
cutting tool containing cubic boron nitride with an average grain
diameter of at most 1 µm, which comprises reducing and nitriding
boron oxide or boric acid in the presence of carbon and nitrogen
to synthesize a low pressure phase boron nitride and subjecting
the resulting low pressure phase boron nitride, as a starting
material, to direct conversion into cubic boron nitride at a high
temperature and high pressure, while simultaneously sintering.
THE REFERENCES
Suzuki et al. (Suzuki) 5,691,260 Nov. 25, 1997
Kawasaki et al. (Kawasaki) 6,096,671 Aug. 1, 2000
(effective filing date Jan. 15, 1997)
Mitsubishi Materials Corp. 9/59068 Mar. 4, 1997
(JP ‘068)2 (Japanese patent application)
2 Citations herein to JP ‘068 are to the English translation
thereof which is of record.
2
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