Stock material or miscellaneous articles – All metal or with adjacent metals – Having metal particles
Patent
1995-03-13
1997-04-29
Jordan, Charles T.
Stock material or miscellaneous articles
All metal or with adjacent metals
Having metal particles
428548, 428552, 407119, B22F 706
Patent
active
056247664
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a coated cemented carbide, and more particularly to a coated cemented carbide which may suitably be used for tools such as cutting tools, wear-resistant tools, impact-resistant tools, and mining tools (particularly, cutting tools suitable for the cutting of general steel, a material having poor machinability or cuttability (hard-to-machine material), etc.).
BACKGROUND ART
Heretofore, as materials for cutting tools for cutting general steel, there has been used P-type cemented carbide according to the JIS (Japanese Industrial Standard) classification, such as alloy comprising a WC-Co alloy and 10 wt % or more of a carbide
itride of Ti, Ta or Nb added thereto. Recently, along with an increase in cutting speed in cutting conditions, there has been increased the proportion of a coated cemented carbide to be used for the cutting tool material. Typically, such a coated cemented carbide comprises a substrate material of an M-type cemented carbide (e.g., an alloy comprising a WC-Co cemented carbide containing 5-10 wt % of a carbide
itride of Ti, Ta or Nb added thereto), the surface of which has been coated with an about 3-10 .mu.m-thick ceramic layer (coating) comprising TiC, TiCN, TiN, Al.sub.2 O.sub.3, etc., by using a vapor-phase deposition process such as chemical vapor deposition (CVD) and physical vapor deposition (PVD).
However, in some cases, when the cemented carbide is covered with the above-mentioned coating, there has been posed a problem such that the coating layer itself comprising a brittle material is liable to provide a defect, or an .eta. phase (a general term for a decarburization phase comprising of Co.sub.3 W.sub.3 C, etc.) is produced at the surface of the substrate material of cemented carbide, thereby to reduce the coating strength. In order to prevent the occurrence of such a defect and/or .eta. phase, various attempts have been made to improve the cemented carbide as a substrate material to be coated.
For example, Japanese Patent Publication (KOKOKU) No. 7349/1984 (i.e., Sho 59-7349) discloses a substrate material for coated cemented carbide which has been caused to contain free carbon so as to suppress the occurrence of the .eta. phase, which is liable to appear at the surface of the cemented carbide substrate at the time of the coating. Further, Japanese Laid-Open Patent Application (KOKAI) No. 97866/1991 (i.e., Hei 3-97866) proposes a tool of coated cemented carbide comprising a substrate material of a cemented carbide having a low carbon content which has been coated by a CVD process using a reactant gas capable of hardly forming the .eta. phase as a starting material. Furthermore, Hisashi Suzuki, "Cemented carbides and Sintered Hard Materials" page 221, (1986) published by Maruzen K.K. (Tokyo, JAPAN) discloses a technique for preventing a decrease in the strength at the time of coating such that a .beta. phase-reduced layer (a phase or layer in which a composite carbide
itride phase such as (W, Ti) (C, N) has disappeared) is formed on the surface of a substrate material for coated cemented carbide so as to increase the Co content in a surface region of the cemented carbide.
The formation of the .eta. phase can be prevented by utilizing the above-mentioned techniques disclosed in Japanese Patent Publication No. 7349/1984 and Japanese Laid-Open Patent Application No. 97866/1991. However, the thickness of the .eta. phase which has been prevented from being formed is as small as about 5 .mu.m, and therefore the effect thereof is not enough to prevent the propagation of a fatigue crack of 100 .mu.m or more which actually poses a problem in practical use of a cutting tool (Atsushi Fukawa, "Powder and Powder Metallurgy" 41 (1), page 3 (1994)). As a result, the actual service life of the resultant cutting tool is still short.
According to the above-mentioned technique for forming the .beta. phase-reduced layer in a cemented carbide substrate material, a region in which the binder phase content has been increased, can be formed in a thic
REFERENCES:
patent: Re32111 (1986-04-01), Lambert et al.
patent: Re34180 (1993-02-01), Nemeth
patent: 4497874 (1985-02-01), Hale
patent: 4686156 (1987-08-01), Baldoni et al.
patent: 4714660 (1987-12-01), Gates, Jr.
patent: 4720437 (1988-01-01), Chudo et al.
patent: 4966627 (1990-10-01), Keshavan et al.
patent: 5116694 (1992-05-01), Tsukada et al.
patent: 5163975 (1992-11-01), Martin
patent: 5181953 (1993-01-01), Nakano et al.
patent: 5188489 (1993-02-01), Santhanam et al.
patent: 5232318 (1993-08-01), Santhanam et al.
patent: 5266389 (1993-11-01), Omori et al.
patent: 5283030 (1994-02-01), Nakano et al.
patent: 5395680 (1995-03-01), Santhanam et al.
Kitagawa Nobuyuki
Kobayashi Mitsunori
Moriguchi Hideki
Nomura Toshio
Uchino Katsuya
Carroll Chrisman D.
Jordan Charles T.
Sumitomo Electric Industries Ltd.
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