Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1995-04-13
1996-10-22
Robinson, Ellis
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428384, 428697, 428699, 428701, 428702, B32B 1800
Patent
active
055675182
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a ceramic composite material comprising matrix and possibly reinforcing materials and an intermediate weak interface material and particularly adapted for use at temperatures above 1400.degree. C. and in oxidizing environment, the matrix and possibly reinforcing materials consisting of the same or different ceramic oxides having a melting point above 1600.degree. C.
BACKGROUND OF THE INVENTION
Ceramic composite materials might be divided into materials reinforced by particles, whiskers or elongated fibres. These materials are prepared by powder processes and sintering or by gas-phase infiltration. The materials hitherto mentioned in the literature often are based on the provision of desired composite characteristics by means of a weak interface material between the matrix and the reinforcing material, preferably fibres, the interface material consisting of carbon or boron nitride, see e.g. Frety, N., Boussuge, M., "Relationship between high-temperature development of fibre-matrix interfaces and the mechanical behaviour of SiC--SiC composites" Composites Sci. Techn. 37 177-189 (1990) and Singh, R. N., "Influence of high temperature exposure on mechanical properties of zircon-silicon carbide composites" J. Mater. Sci. 26 117-126 (1991), respectively.
Both carbon and boron nitride have a layered structure which makes them weak in one direction and this can be utilized for deflecting cracks along the interface between fibre and matrix. Both carbon and boron nitride, however, are very sensitive to oxidation which starts at relatively low temperatures of about 500.degree.-800.degree. C. In order to enable the use of ceramic composites at high temperatures in oxidizing atmosphere, such as in combustion chambers of gas turbines, rocket nozzles etc. other oxidation-resistent weak interface materials are required. An attempt to provide such materials has been mentioned in Carpenter, H. W., Bohlen, J. W., "Fiber coatings for ceramic matrix composites" Ceram. Eng. Sci. Proc. vol 13 9-10 (1992). In Carpenter, composites have been manufactured with SiC fibres and a layered SiC interface in an SiC matrix. Experiments also have been made with interfaces of a porous oxide in a SiC/SiC composite. However, SiC is stable in an oxidizing environment only up to 1000.degree. C., at higher temperatures a SiO.sub.2 layer always is formed on the surface in oxidizing atmosphere. Often SiO.sub.2 is not stable together with other oxides but reacts therewith and forms strong bonds to adjacent materials. Therefore, SiO.sub.2 does not constitute a useful interface material in the present connection. Thus there is still a need for improved composite materials which might be used in oxidizing environments at temperatures above 1400.degree. C.
SUMMARY OF THE INVENTION
The object of the present invention is to suggest such a ceramic Composite material and the feature essentially distinguishing the invention is that the interface material consists of one or more ceramic oxides not exhibiting solid solubility, eutecticum below the temperature of manufacture, use or reaction with any of the matrix or possibly reinforcing materials and in combination with the materials providing a stress field liable to micro-cracking, the matrix and reinforcing materials being substantially pure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
One of the most obvious interface materials is ZrO.sub.2 which fulfills the requirements as to oxidation resistance and good high temperature characteristics. In U.S. Pat. No. 4,732,877 an interface of ZrO.sub.2 in a composite of Al.sub.2 O.sub.3/Al.sub.2 O.sub.3 has been suggested. According to this patent, however, the only object of ZrO.sub.2 is to act as a diffusion barrier and prevent a reaction between reinforcing fibres and matrix. The interface obtained is strong by its binding to the materials and not weak as is necessary in ceramic composites for the present use.
Thus the present invention refers to an interface material for a ceramic composite m
REFERENCES:
patent: 4298385 (1981-11-01), Claussen et al.
patent: 4767727 (1988-08-01), Claussen et al.
patent: 5017528 (1991-05-01), Tiegs et al.
patent: 5110771 (1992-05-01), Carpenter et al.
patent: 5137852 (1992-08-01), Morgan
patent: 5190820 (1993-03-01), Millard
patent: 5231061 (1993-07-01), Devore
Butler Edwin
Lundberg Robert
Pejryd Lars
Jones III Leonidas J.
Robinson Ellis
Rolls Royce plc
Volvo Aero Corporation
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