Interfaces of polymeric precursors with ceramics/metals

A novel method for synthesizing, modifying and curing silicon-based preceramic polymers, utilizing a catalyst, Ru sub 3 (CO) sub 12 , allows preparation of precursors to many ceramic compositions and synthesis of polymers with a wide range of viscosities and high ceramic yields. Examples using polycyclomethylsilazane (PCMS) and polyhydridomethylsiloxane (PHMSO) illustrate the growth of silicon nitride whiskers in situ to toughen silicon nitride, in production of mullite with approx4% shrinkage and near-net-shape and mullite coatings. Micros show spherical PCMS/Si sub 3 N sub 4 /oxide powders mixed by a proprietary technique and microstructures of resulting pyrolyzed and sintered parts using 0, 15 and 20% PCMS. 20% PCMS appears optimum. Coatings applied by painting or airbrushing the mullite precursor mixture were 10-30 mu m thick and were adherent to aluminum, glass, steel and other substrates. Surface and interface micros show coatings on Al foil substrate.