Cemented carbide, cutting tool containing the same, and method of manufacturing cemented carbide

Patent metadata

Field	Value
Publication number	US-11401587-B2
Application number	US-201916606940-A
Country	US
Kind code	B2
Filing date	Jan 29, 2019
Priority date	Apr 26, 2018
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

Cemented carbide contains first hard-phase particles containing WC, second hard-phase particles which contain carbonitride containing at least Ti and Nb, and a metallic binder phase containing an iron-group element. The second hard-phase particle includes a granular core portion. The core portion contains composite carbonitride expressed as Ti1-X-YNbXWYC1-ZNZ, where X is not smaller than 0.1 and not greater than 0.2, Y is not smaller than 0 and not greater than 0.05, and Z is not smaller than 0.3 and not greater than 0.6. The cemented carbide has an absolute value of a difference not greater than 10, between a ratio (%) of an area occupied by the second hard-phase particles at a surface thereof and a ratio (%) of an area occupied by the second hard-phase particles in a region extending from the surface by 0.5 mm in a direction of depth.

First claim

The invention claimed is:

1. Cemented carbide comprising:
first hard-phase particles containing WC;
second hard-phase particles which contain carbonitride containing at least Ti and Nb; and
a metallic binder phase containing an iron-group element,
the second hard-phase particle including a granular core portion and a peripheral portion which covers at least a part of the core portion,
the core portion containing composite carbonitride expressed as Ti 1-X-Y Nb X W Y C 1-Z N Z , where X is not smaller than 0.1 and not greater than 0.2, Y is not smaller than 0 and not greater than 0.05, and Z is not smaller than 0.3 and not greater than 0.6,
the peripheral portion being different in composition from the core portion,
the cemented carbide having an absolute value of a difference not greater than 10, between a ratio (%) of an area occupied by the second hard-phase particles at a surface of the cemented carbide and a ratio (%) of an area occupied by the second hard-phase particles in a region extending from the surface by 0.5 mm in a direction of depth.

2. The cemented carbide according to claim 1 , wherein
in the core portion, a total amount of V, Cr, and Mo occupied in a total amount of Ti, Nb, W, V, Cr, and Mo is smaller than 2 atomic %.

3. The cemented carbide according to claim 1 , wherein
the core portion has a particle size at 50% in a number-based cumulative distribution not greater than 1.5 μm.

4. The cemented carbide according to claim 1 , wherein
a volume ratio of the core portion in the cemented carbide is not lower than 2 volume % and not higher than 20 volume %.

5. A cutting tool comprising the cemented carbide according to claim 1 .

6. The cutting tool according to claim 5 , comprising:
a substrate composed of the cemented carbide; and
a coating film which covers the substrate.

7. A method of manufacturing cemented carbide comprising:
preparing powders of composite carbonitride expressed as Ti 1-X-Y Nb X W Y C 1-Z N Z , WC powders, and powders of an iron-group element;
obtaining mixed powders by mixing the powders of the composite carbonitride, the WC powders, and the powders of the iron-group element;
obtaining a formed material by pressing the mixed powders; and
obtaining a sintered material by sintering the formed material,
X being not smaller than 0.1 and not greater than 0.2,
Y being not smaller than 0 and not greater than 0.05,
Z being not smaller than 0.3 and not greater than 0.6,
the cemented carbide obtained by the method of manufacturing cemented carbide having an absolute value of a difference not greater than 10, between a ratio (%) of an area occupied by second hard-phase particles containing the composite carbonitride at a surface of the cemented carbide and a ratio (%) of an area occupied by the second hard-phase particles in a region extending from the surface by 0.5 mm in a direction of depth, wherein
in the obtaining a sintered material, the formed material is sintered under such sintering conditions as a nitrogen partial pressure not lower than 7 kPa and not higher than 15 kPa, a holding temperature not lower than 1300° C. and not higher than 1600° C., and a holding time period not shorter than 0.5 hour and not longer than 2 hours.

Assignees

• Sumitomo Electric Industries

Inventors

• FUKAE Kosuke
• Gotou Hiroaki
• Michiuchi Masato
• Tsuda Keiichi

Classifications

• C22C29/02 Primary

  based on carbides or carbonitrides · CPC title

• C22C1/051

  Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor · CPC title

• C22C29/08 Primary

  based on tungsten carbide · CPC title

• B22F2005/001

  Cutting tools, earth boring or grinding tool other than table ware · CPC title

• C22C29/067

  comprising a particular metallic binder · CPC title