Ceramic Matrix Composites (CMC)
topic
CMC systems: SiC/SiC (SiC fibres in SiC matrix—jet engines, heat exchangers), oxide/oxide (alumina fibres in alumina or mullite matrix—lower performance but oxidation resistant), and C/SiC (carbon fibres in SiC matrix—brake discs, thermal protection). Matrix infiltration: chemical vapor infiltration (CVI), polymer infiltration and pyrolysis (PIP), slurry infiltration, or melt infiltration. Fibre coating (BN, PyC 100-500 nm) critical for weak interface enabling toughness.
Role
CMCs combine ceramic fibre reinforcement with ceramic matrix creating materials with metal-like toughness (not brittle monolithic ceramic), 50% weight reduction vs. superalloys, enabling 100-200°C temperature increase in gas turbines translating to 1-2% fuel efficiency improvement worth $1-2M annually per engine.