Ceramic fibers for matrix composites in high-temperature engine applications

High-temperature engine applications have been limited by the performance o f metal alloys and carbide fiber composites at elevated temperatures. Rando m inorganic networks composed of silicon, boron, nitrogen, and carbon repre sent a novel class of ceramics with outstanding durability at elevated temp eratures. SIBN3C was synthesized by pyrolysis of a preceramic N-methylpolyb orosilazane made from the single-source precursor Cl3Si-NH-BCl2. The polyme r can be processed to a green fiber by melt-spinning, which then undergoes an intermediate curing step and successive pyrolysis. The ceramic fibers, w hich are presently produced on a semitechnical scale, combine several desir ed properties relevant for an application in fiber-reinforced ceramic compo sites: thermal stability, mechanical strength, high-temperature creep resis tivity, low density, and stability against oxidation or molten silicon.