Interfacial characterization of a slurry-cast melt-infiltrated SiC/SiC ceramic-matrix composite

An SiC-particulate, silicon-metal melt-infiltration-matrix composite reinfo rced with SiC fibers is being developed for combustor applications under th e High Speed Civil Transport (HSCT) Enabling Propulsion Material (EPM) Prog ram. A major part of this effort has dealt with the characterization and op timization of the boron nitride (BN) based fiber/matrix interface. BN was c hosen as the primary interfacial material due to its inherently weak struct ure and thus good crack-deflecting ability, ease of deposition by chemical vapor infiltration (CVI) into woven fiber preforms, and relatively good env ironmental stability. Topics discussed in this paper include an overview of the differences in composite microstructure between the EPM SiC/SiC materi al and a more conventional CVI SiC/SiC composite material, the microstructu re/property relationships for the EPM SiC/SiC composite with two different types of SiC fiber (High-Nicalon and Sylramic(TM)), and the effect of moist , high-temperature environments on the stability of the BN interface. (C) 2 000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. AII rights re served.