Non-oxide and oxide ceramics from preceramic polymers for composite components

Non-oxide and oxide ceramics based on unfilled and filled preceramic polymers were synthesized for applications as matrices (and fibers) for ceramic matrix composites. Two examples are given. Silazane precursors with tailored properties (i.e. ceramic yield, viscosity, setting behavior) were prepared, starting from functionalized chlorosilanes. Thermoanalytical analysis was used to investigate the organic/inorganic transition. Emphasis was put on TEM-studies to reveal aspects of the complex crystallization behavior of the polymer derived amorphous glasses, which is especially important with respect to fiber degradation processes. Monolithic synthetic mullite with low shrinkage, potentially serving as a polymer derived oxide matrix for fiber reinforced composites, was prepared from siloxane/Al2O3- and siloxane/Al-mixtures by reaction bonding processes, thus demonstrating the usefulness of filled polysiloxane systems for the synthesis of stoichiometric silicates.