Patent ID: 11920222
Assignee: SUMITOMO ELECTRIC HARDMETAL CORP.
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 10:
11. A composite sintered material comprising: a plurality of diamond grains having an average grain size of less than or equal to 2 μm; a plurality of cubic boron nitride grains having an average grain size of less than or equal to 1 μm; a plurality of aluminum oxide grains having an average grain size of less than or equal to 0.2 μm; and a remainder of a binder phase, wherein
at least parts of adjacent diamond grains are bound to one another,
the binder phase includes cobalt and a chemical component including at least one element selected from a group consisting of tungsten, titanium, zirconium, hafnium, niobium, tantalum, chromium, aluminum, silicon, and molybdenum, and
in the binder phase, a content of the cobalt is more than or equal to 50 mass % and less than or equal to 99.5 mass %, and a content of the chemical component is more than or equal to 0.5 mass % and less than or equal to 50 mass %,
at least a part of the binder phase is at least one of a carbide, a carbonitride, a nitride, an oxide, an oxynitride, and a boride,
in the composite sintered material, a content of the diamond grains is more than or equal to 50 volume % and less than or equal to 70 volume %, a content of the cubic boron nitride grains is more than or equal to 10 volume % and less than or equal to 30 volume %, a content of the aluminum oxide grains is more than or equal to 2 volume % and less than or equal to 15 volume %, and a content of the cobalt is more than or equal to 5 volume % and less than or equal to 15 volume %,
in a visual field having a longitudinal side of 18 μm and a lateral side of 23 μm within an arbitrarily specified cross section, twenty straight lines are drawn, comprising ten straight lines in a longitudinal direction and ten straight lines in a lateral direction in a form of a lattice to divide the visual field into eleven equal portions in the longitudinal direction and divide the visual field into eleven equal portions in the lateral direction,
wherein for each line segment in a number of line segments on the twenty straight lines, a distance between adjacent aluminum oxide grains with a grain size of more than or equal to 0.1 μm located on each line segment is more than or equal to 0.2 μm,
wherein each line segment in a total number of line segments on the twenty straight lines is connected between corresponding adjacent aluminum oxide grains,
a ratio of the number of line segments with respect to the total number of line segments is more than or equal to 90%, and
less than or equal to one aluminum oxide grain having a grain size of more than or equal to 1 μm exists in the visual field having the longitudinal side of 18 μm and the lateral side of 23 μm within the arbitrarily specified cross section.