Stock material or miscellaneous articles – Composite – Of metal
Patent
1992-10-26
1994-10-04
Turner, Archene
Stock material or miscellaneous articles
Composite
Of metal
428697, 428698, 428699, 428701, 428702, B41M 540
Patent
active
053525337
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application of PCT/EP91/00980 filed May 28, 1991 and based upon German applications P4017651.7 and P4028217.1 filed Jun. 1, 1990 and Sep. 6, 1990 respectively under the International Convention.
FIELD OF THE INVENTION
The invention relates to a fiber-reinforced ceramic composite body with the following components: and/or or VIa of the periodic table of elements and/or oxides of Group IV of the periodic table of elements up to 40% by mass, and
further to a process for the production of a ceramic composite body of the aforementioned kind whereby the initial powders are mixed, wet ground, dried, optionally granulated, subjected to uniaxial or cold isostatic pressing, the resulting composite body being sintered at 1450.degree. C. to 1800.degree. C. and subsequently subjected to hot isostatic supplementary compression (HIP) under a pressure of 5 to approximately 2000 bar.
BACKGROUND OF THE INVENTION
As described in the German publication "ZWF", Zeitschrift fur wirtschaftliche Fertigung und Automatisierung, Year 83, Pages 354 to 359, (1988), the efforts for extending the application field of ceramic cutting materials have lately lead to development of ceramic materials on a basis of Al.sub.2 O.sub.3 reinforced with SiC whiskers. The embedding of SiC whiskers has a positive effect primarily on the mechanical characteristics and the performance when used as a cutting body. Samples containing whiskers are characterized particularly by considerably higher hardness and a higher tenacity and a correspondingly lower breaking risk, when compared with whiskerless samples.
Furthermore, the EP 0 208 910 proposes a fiber-reinforced ceramic material for tools, which has the following components: consisting of CaO, MgO, SiO.sub.2, NiO, Y.sub.2 O.sub.3, as well as lanthanum dioxide; as well as at least one of the component (C) and (D), whereby comprising B, C, AlN, B.sub.4 C as well as the borides of Si, Al, Y and Lanthanum, and IVa, Va, as well as VIa of the periodic table of elements, respectively oxides, carbides, nitrides or borides thereof, including solid solutions of the same, and weight.
OBJECTS OF THE INVENTION
It is the object of the present invention to improve the mechanical characteristics of the ceramic composite body. Another object of the invention is to improve the breaking resistance, the bending strength and the resistance to temperature variations of the ceramic composite body.
Yet another object of the present invention is to provide a process capable of achieving the ceramic composite body according to the invention.
SUMMARY OF THE INVENTION
These object are achieved in the fiber-reinforced ceramic composite containing 0.05 to 10% by mass nickel and/or cobalt and/or iron in proportion to the total mass.
Preferably at least 0.4 to 3% by mass of nickel and/or cobalt and/or iron are used.
Comparatively good strength characteristics can be still obtained when up to 25% by mass of the nickel and/or cobalt and/or iron are replaced by chromium.
According to one of the embodiments of the invention, 2% by mass of one or several precious metals can be added to the ceramic composite body. Under precious metals such elements as silver, gold, platinum, iridium, rhodium, rhutenium, palladium and osmium are implied, whereby especially platinum and/or palladium are recommended from the point of view of their sintering characteristics.
According to another embodiment of the invention, the proportion of SiC whiskers in the ceramic composite body of the invention can be replaced completely or partially, preferably up to 80% by mass, by Si lamellae (platelets).
In order to improve the sintering capability, the SiC whiskers and/or monocrystalline Si-lamellae (platelets) can be replaced up to 2/3 of their total mass by an addition of SiC powder.
According to the invention an improvement of the strength characteristics takes place also due to an addition of zirconium or hafnium oxide, respectively silicon nitride, which are embedded in the
Dreyer Klaus
Kassel Dieter
Kolaska Hans
Dubno Herbert
Kateshov Yuri
Krupp Widia GmbH
Turner Archene
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