| (19) |
 |
|
(11) |
EP 0 487 008 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
14.07.1993 Bulletin 1993/28 |
| (43) |
Date of publication A2: |
|
27.05.1992 Bulletin 1992/22 |
| (22) |
Date of filing: 19.11.1991 |
|
| (51) |
International Patent Classification (IPC)5: C23C 30/00 |
|
| (84) |
Designated Contracting States: |
|
DE FR GB IT SE |
| (30) |
Priority: |
20.11.1990 JP 314874/90
|
| (71) |
Applicant: MITSUBISHI MATERIALS CORPORATION |
|
Chiyoda-ku
Tokyo (JP) |
|
| (72) |
Inventors: |
|
- Tanaka, Tetsuya,
c/o Tsukuba-Seisakusho
Ishige-machi,
Yuuki-gun,
Ibaraki-ken (JP)
- Kunugi, Hitoshi,
c/o Tsukuba-Seisakusho
Ishige-machi,
Yuuki-gun,
Ibaraki-ken (JP)
|
| (74) |
Representative: Türk, Gille, Hrabal, Leifert |
|
Brucknerstrasse 20
40593 Düsseldorf
40593 Düsseldorf (DE) |
|
| |
|
| (54) |
Blade member of tungsten carbide based cemented carbide with hard coating |
(57) There is disclosed a blade member of tungsten carbide based cemented carbide with
a hard coating, which includes a substrate of tungsten carbide based cemented carbide
and a hard coating of one or more coating layers deposited thereon. The substrate
contains a binder phase of 5 to 13% by weight of cobalt, and a hard dispersed phase
of no greater than 17 % by weight of hard-phase constituents, and a balance tungsten
carbide. Each coating layer is formed of one substance of a carbide, a nitride and
an oxide of a metal in IV
A, V
A and VI
A of the Periodic Table. The substrate is such that a parameter R, cal/(cm)(sec), defined
by (λ x σ )/(σ x E ) and representing thermal shock resistance of the substrate takes
a value of no less than 100, wherein λ, σ, α and E denote thermal conductivity, transverse
rupture strength, coefficient of thermal expansion and Young's modulus of the substrate,
respectively.