Manufacturing of continuous fibre reinforced ceramics is the only alternative to realize thin walled, integral light weight structures for high temperature applications (T>1200 deg C). There exist two main routes to fabricate ceramic matrix composite (CMC) materials: chemical vapour infiltration (CVI) and liquid phase infiltration. One manufacturing method of the latter route currently under development at the DLR (Deutsche Forschungsanstalt für Luft- und Raumfahrt) Institute of Structures and Design is the Liquid Silicon Infiltration (LSI). This manufacturing process is based on conventionally produced carbon fibre-reinforced plastics (CFRP), containing a polymer matrix with a high char yield. The second step is the pyrolysis of the CFRP to a porous carbon/carbon (C/C). During the subsequent liquid silicon infiltration, the silicon reacts with the remaining carbon matrix forming silicon carbide, thus resulting in an internal oxidation protection of the C/C material. It is noteworthy, that all three manufacturing steps (CFRP, C/C, C/C-SiC) are carried out by an one-shot fabrication method without any re-infiltration steps, resulting in a low cost manufacturing process. At temperature above 400 deg C, carbon fibre-containing composite materials oxidize in air very rapidly. Thus these materials need an additional protective coating, mainly on cut surfaces, which effectively prevents oxidation. Among other methods, the polymer pyrolysis is one interesting possibility for the manufacture of protective coatings. In this method soluble and fusible organic silicon polymers, especialy polysilazanes are used as starting materials. These pre-ceramic polymers become cross-linked by thermal, chemical or photochemical treatment. Because of this, insoluble and infusible materials are formed. The following thermal decomposition (pyrolysis) up to 1100 deg C in a suitable atmosphere leads to amorphous ceramics of the type SI/C/N, which show very good oxidation resistance.
Development of oxidation protected Carbon/Carbon
Entwicklung von carbonfaserverstärkten Kohlenstoffen mit Oxidationsschutzschichten
Zeitschrift für Flugwissenschaften und Weltraumforschung ; 19 , 3 ; 180-188
1995
9 Seiten, 19 Bilder, 3 Tabellen, 23 Quellen
Article (Journal)
English
Faserverstärkung , Carbonfaser , Verbundwerkstoff , Hochtemperaturwerkstoff , Gewichtsverminderung , Flüssigkeit , Eindringen , Silicium , Matrix (Grundmasse) , Pyrolyse , Porosität , Siliciumcarbid , chemische Reaktion , Kostenersparnis , Oxidation , amorpher Stoff , Keramik , Raumfähre , Thermogravimetrie , Erosion , Hitzeschild , Oxidationsbeständigkeit , chemische Dampfphaseninfiltration , Keramikverbundstoff , Polysilazan
Development of oxidation protected Carbon-Carbon
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