Finishing Process to Improve Interfacial Bonding in SiC/BMI Composites Navy SBIR FY2005.1 Sol No.: Navy SBIR FY2005.1 Topic No.: N05-025 Topic Title: Finishing Process to Improve Interfacial Bonding in SiC/BMI Composites Proposal No.: N051-025-0601 Firm: Adherent Technologies, Inc. 9621 Camino del Sol NE Albuquerque, New Mexico 87111-1522 Contact: Phone: Web Site: www.adherent-tech.com Abstract: High-temperature polymer matrix composites (PMCs) are desired for the aggressive environments encountered in many aerospace and military applications. These have required new blends of materials properties in the composite fiber and matrix. As polyimide resins have been improved, the thermo-oxidative stability (TOS) of the carbon fibers typically used as reinforcements have become a limiting factor for applications ranging from propulsion systems to structures for the orbiting space plane. Silicon carbide fibers provide a potentially attractive replacement for carbon fibers because of their higher thermal stability. Sizings for SiC fibers are not compatible with the new high-temperature matrix resins, which compromises composite properties. A need exists for a SiC fiber adhesion promoting finish that is compatible with high-temperature imide chemistries. Previous work has revealed chemistries that chemically bond to carbon fiber surfaces and high-temperature curing matrix resins. Composites fabricated with finishes based on these reactive coupling agent chemistries show substantially higher interface-dependent properties, TOS, and moisture resistance. The also function as weaving aids. Those chemistries will be modified to improve the interfacial bond between silicon carbide fibers and bismaleimide resins in the Phase I program. Results are expected to show that the modified reactive finishes allow control of interfacial adhesion in SiC/BMI composite systems that imparts superior interfacial strength and environmental durability. Benefits: Improved SiC/polyimide composites will find numerous applications in high-temperature environments including propulsion systems, reentry structures, and exploratory spacecraft. The finish chemistry for SiC fibers will see applications in propulsion systems for commercial and military aircraft such as the Pratt & Whitney F135 engine for the joint strike fighter. Versions of the finish chemistry will find large markets in the specialty composites industry. Return