# US 2008/0187778 A1 · Cemented carbide body

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- Number: US 2008/0187778 A1
- Document ID: US20080187778A1
- Status: Published application
- Kind: A1
- Application number: 12/078,140
- Filed: 2008-03-27
- Published: 2008-08-07
- Earliest claimed: 2000-11-23
- Assignees: Sandvik Intellectual Property AB
- Inventors: Marian Mikus
- Web page: https://patentgrep.com/patent/US20080187778A1

## CPC

- C23C 8/20: Carburising
- C22C 29/08: based on tungsten carbide
- C23C 8/80: After-treatment
- C23C 30/005: {on hard metal substrates}
- B22F 2005/001: {Cutting tools, earth boring or grinding tool other than table ware}
- B22F 2998/00: Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F 2998/10: Processes characterised by the sequence of their steps
- Y10T 428/12063: Nonparticulate metal component
- Y10T 428/24942: including components having same physical characteristic in differing degree
- Y10T 428/252: Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

According to the present invention there is now provided a body cemented carbide provided with at least one wear resistant layer, which body contains a toughness increasing surface zone. Increase in toughness is obtained due to the presence of a surface zone having increased WC grain size and/or increased Co content. The invention is most suitable for WC-Co cemented carbides.

## Claims

### Claim 1

A WC+Co based cemented carbide body, with a carbon content below the saturation point, with or without addition of<about 3 weight % grain growth inhibitors having a nominal average WC grain size of from about 0.3 to about 3 μm containing from about 3 to about 12 weight % binder phase, comprising at least one of the elements Co, Ni, Fe with about 5 to about 100 μm thick surface zone different from the interior of the body, said surface zone being free of eta phase and wherein within the entire thickness of the surface zone the WC grains have an average grain size within the range of ±20% the same as the nominal average WC grain size, together with an average Co content at least 10% higher than the nominal Co content.

### Claim 2 (depends on 1)

The WC+Co based cemented carbide body of claim 1 wherein the body also comprises <3 weight % grain growth inhibitors.

### Claim 3 (depends on 1)

The WC+Co based cemented carbide body of claim 1 wherein the body also comprises<2.50% grain growth inhibitors.

### Claim 4 (depends on 1)

The WC+Co based cemented carbide body of claim 1 wherein the average grain size is from about 0.5 to about 1.7 μm.

### Claim 5 (depends on 1)

The WC+Co based cemented carbide body of claim 1 wherein the binder phase comprises Co.

### Claim 6 (depends on 1)

The WC+Co based cemented carbide body of claim 1 wherein the surface zone is from about 5 to about 30 μm thick.

### Claim 7 (depends on 1)

The WC+Co based cemented carbide body of claim 1, comprising an intermediate zone between the surface zone and the interior of the body, wherein the intermediate zone has a thickness from about 100% up to about 200% the thickness of the surface zone,
wherein WC grains in the intermediate zone has an average grain size from about 10 to about 30% smaller than the nominal average WC grain size, and wherein a Co content within the intermediate zone is within the range of ±10% the nominal Co content or is within from about 10% to about 30% lower than the nominal Co content.

### Claim 8 (depends on 1)

The WC+Co based cemented carbide body of claim 1, comprising an intermediate zone between the surface zone and the interior of the body,
wherein WC grains in the intermediate zone has an average grain size less than the nominal average grain size, and
wherein the Co content in the cemented carbide body is below about 8 weight % without grain growth inhibitors.

### Claim 9

WC+Co based cemented carbide body, with a carbon content below the saturation point with addition of<about 3 weight % grain growth inhibitors having a nominal average WC grain size of from about 0.5 to about 1.7 μm containing from about 3 to about 12 weight % binder phase, comprising at least one of the elements Co, Ni, Fe with about 5 to about 30 μm thick surface zone different from the interior of the body, said surface zone being free of eta phase and wherein within the entire thickness of the surface zone the WC grains have an average grain size within the range of ±20% the same as the nominal average WC grain size, together with an average Co content at least 30% higher than the nominal Co content.

### Claim 10 (depends on 9)

The WC+Co based cemented carbide body of claim 9 wherein a thickness of the surface zone on a cutting edge is greater than a thickness of the surface zone on a plane surface.

### Claim 11 (depends on 9)

The WC+Co based cemented carbide body of claim 9 wherein a thickness of the surface zone on a cutting edge is 10% to 90% of a thickness of the surface zone on a plane surface.

### Claim 12 (depends on 9)

The WC+Co based cemented carbide body of claim 9 wherein the surface zone is removed at outermost portions of the cutting edge within a distance of 10 to φμm measured at a cross section of the cutting edge.

### Claim 13 (depends on 9)

The WC+Co based cemented carbide body of claim 9, comprising an intermediate zone between the surface zone and the interior of the body, wherein the intermediate zone has a thickness from about 100% up to about 200% the thickness of the surface zone, wherein WC grains in the intermediate zone has an average grain size from about 10 to about 30% smaller than the nominal average WC grain size, and wherein a Co content within the intermediate zone is within the range of ±10% the nominal Co content or is within from about 10% to about 30% lower than the nominal Co content.

### Claim 14 (depends on 9)

The WC+Co based cemented carbide body of claim 9, comprising an intermediate zone between the surface zone and the interior of the body, wherein WC grains in the intermediate zone has an average grain size less than the nominal average grain size, and
wherein the Co content in the cemented carbide body is below about 8 weight % without grain growth inhibitors.