Light-weight cellular ceramics from biologically-derived preforms

Advanced high-temperature, cellular materials can be prepared by using biol ogically-derived preforms as structural templates for ceramic composites. T wo different processing routes will be presented in the paper. First, cellu lar ceramics with anisotropic pore structures at the micrometer level were processed by infiltrating liquid metal (silicon) into carbonized wood struc tures and subsequent reaction into SiC and SiSiC-ceramics at temperatures o f 1600 degrees C. Secondly, low viscosity preceramic polymer/filler (silico n and aluminum) suspensions were infiltrated into 3-dimensional preprocesse d paper structures having microstructures of various porosity and subsequen tly converted into high-temperature stable ceramic composites using a fille r controlled reaction pyrolysis at 1450 degrees C. The resulting lightweigh t, cellular ceramic composites display low density, while having high speci fic strength and excellent high temperature stability.