Thermoplastic Forming as an Alternative Shaping Process for Near-Net-Shape Production of C-SiSiC Ceramics via Liquid Silicon Infiltration (LSI) Process

摘要

The present study demonstrated the feasibility of producing carbon-based green bodies by means of extrusion, pyrolysis and subsequent conversion to C-SiSiC ceramics according to the LSI process. A thermoplastic binder system was used for the development of feedstocks that differ from conventional duroplastic binder systems as these would have created difficulties during processing owing to their curing behavior. Activated carbon, carbon fibers and semi-coke were used as fillers and a source of a sufficiently stable carbon backbone in the carbonized intermediate. Special attention was paid to the characterization and quantification of material behavior at the water debinding step as well ad at thermal treatment during pyrolysis. Porosity and microstructural characteristics of carbon bodies and subsequent C-SiSiC microstructure after Si-infiltration were investigated by means of scanning electron microscopy and porosity measurements. The feasibility of producing carbon-based extrusion feedstocks with high homogeneity and flowability which can be converted into SiC by means of LSI shows that the concept may be applied to production of near-shape C-SiSiC components by means of thermoplastic injection molding.