US 12,391,552 B2
Polycrystalline cubic crystal boron nitride and tool
Hitoshi Sumiya, Osaka (JP); and Yuh Ishida, Osaka (JP)
Assigned to Sumitomo Electric Industries, Ltd., Osaka (JP)
Appl. No. 17/762,072
Filed by SUMITOMO ELECTRIC INDUSTRIES, LTD., Osaka (JP)
PCT Filed Jul. 20, 2020, PCT No. PCT/JP2020/028038
§ 371(c)(1), (2) Date Mar. 20, 2022,
PCT Pub. No. WO2021/059700, PCT Pub. Date Apr. 1, 2021.
Claims priority of application No. 2019-174432 (JP), filed on Sep. 25, 2019.
Prior Publication US 2022/0371891 A1, Nov. 24, 2022
Int. Cl. B23B 27/14 (2006.01); C01B 21/04 (2006.01); C01B 21/064 (2006.01); C04B 35/5831 (2006.01); B23C 5/16 (2006.01)
CPC C01B 21/064 (2013.01) [B23B 27/148 (2013.01); C04B 35/5831 (2013.01); B23B 27/14 (2013.01); B23B 2226/125 (2013.01); B23C 5/16 (2013.01); C01P 2002/76 (2013.01); C01P 2004/03 (2013.01); C01P 2004/54 (2013.01); C01P 2004/64 (2013.01); C01P 2006/90 (2013.01); C04B 2235/386 (2013.01)] 11 Claims
 
1. A polycrystalline cubic boron nitride comprising:
a cubic boron nitride particle group wherein
the polycrystalline cubic boron nitride has a ratio of a second length to a first length of 0.99 or less,
each of the first length and the second length is a value measured on a surface of the polycrystalline cubic boron nitride with an indentation formed by a Knoop hardness test under conditions specified in ISO4545-1 and ISO4545-4,
the test force of the Knoop hardness test is 4.9 N,
the second length represents the length of the longer diagonal of the indentation,
the first length represents the sum of the second length and the length of a streaky indentation,
the streaky indentation extends from both ends of the longer diagonal of the indentation toward the outside of the indentation,
the length of the streaky indentation is measured by observing the surface of the polycrystalline cubic boron nitride with a field emission scanning electron microscope at a magnification of no less than 5000 times and no more than 10000 times, and
the second length is measured by observing the surface of the polycrystalline cubic boron nitride with an optical microscope at a magnification of no less than 500 times and no more than 1000 times.