Forced Flow Thermal Gradient Chemical Vapor Infiltration (FCVI) of Complex-Shape

The proposed project aims to contribute to the scalability, yield, rate, and cost of manufacturing the newest class of structural materials for high-temperature applications. Ceramic matrix composites (CMCs) are in ever-increasing demand to elevate performance and efficiency, which will enable next-generation innovations for industrial gas turbines, heat exchangers, aero engines, space reentry vehicles, and nuclear fission and fusion reactors. Chemical vapor infiltration (CVI) deposits a highly stoichiometric silicon carbide (SiC) matrix material for structural CMCs that can operate at temperatures > 1450 °C. However, the current state-of-the-art isothermal/isobaric CVI (ICVI) process used for manufacturing CMC components today is expensive. Previous work at ORNL resulted in the development of a process termed forced-flow, thermal-gradient CVI (FCVI), which demonstrated a reduction in processing time by an order of magnitude and a practical increase in CMC thickness. FCVI is being used to densify carbon/silicon carbide (C/SiC) aircraft brakes, but to date its use has been limited to simple flat puck and disk configurations using machined hot and cold graphite mandrels. This project will design and fabricate a new FCVI reactor and employ complex-shaped mandrels fabricated by additive manufacturing of carbon preforms with subsequent pyrolysis and graphitization. This project will demonstrate FCVI to deposit SiC on a curved component shape.