Cubic boron nitride sintered body and method of preparing the same
AssigneeSumitomo Electric Industries, Ltd.
InventorHitoshi Sumiya
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Abstract
A cubic boron nitride sintered body has sufficient strength, hardness, heat resistance and heat dissipativity for serving as a cutting tool. A method of preparing a cubic boron nitride sintered body involves preparing a low-pressure phase boron nitride as a starting material by reducing a compound containing boron and oxygen with a compound containing nitrogen and carbon. Then, the low-pressure phase boron nitride starting material is directly converted to a cubic boron nitride sintered body by subjecting the starting material to a high temperature and a high pressure. In the obtained cubic boron nitride sintered body, the ratio I.sub.220 /I.sub.111 of X-ray diffraction intensity I.sub.220 on the (220) plane relative to X-ray diffraction intensity I.sub.111 on the (111) plane is at least 0.1.
Claims27
A method of preparing a cubic boron nitride sintered body comprising the steps of:
- a) preparing a low-pressure phase boron nitride starting material by reducing a first compound containing boron and oxygen with a second compound containing carbon and nitrogen;
- and
- b) directly convertin said low-pressure phase boron nitride starting material to cubic boron nitride under a high temperature and high pressure condition adequate for converting low-pressure phase boron nitride to cubic boron nitride, and simultaneously performing sintering to form said cubic boron nitride sintered body;
- wherein said steps a) and b) are carried out in such a manner so that said cubic boron nitride sintered body has a crystal characteristic exhibiting a first X-ray diffraction intensity (I.sub.220) on a (220) crystal plane and a second x-ray diffraction intensity (I.sub.111) on a (111) crystal plane, with a ratio (I.sub.220 /I.sub.111) of said first intensity (I.sub.220) relative to said second intensity (I.sub.111) being at least 0.1.
A cubic boron nitride sintered body prepared by directly converting to cubic boron nitride, and simultaneously sintering, a low-pressure phase boron nitride starting material under a high temperature and high pressure condition adequate for converting low-pressure phase boron nitride to cubic boron nitride, wherein said sintered body has a crystal characteristic exhibiting a first X-ray diffraction intensity (I.sub.220) on a (220) crystal plane and a second X-ray diffraction intensity (I.sub.111) on a (111) crystal plane, with a ratio (I.sub.220 /I.sub.111) of said first intensity (I.sub.220) relative to said second intensity (I.sub.111) being at least 0.1.
Dependencies are inferred from the claim text.