Silicon carbide-fiber-reinforced silicon carbide ceramic-matrix composites (SiC/SiC CMCs) are proposed to replace nickel-based superalloys in next-generation gas-turbine engines. SiC/SiC CMCs can increase engine efficiency by operating at higher combustion temperatures and decrease the weight of engine components. A SiC/SiC CMC is composed of SiC fibers coated with a thin boron nitride layer (<1 µm), which are embedded in a SiC matrix.

At elevated temperatures in a dry oxygen environment, SiC/SiC CMCs possess excellent oxidation resistance because of the formation of a solid, slow-growing, protective silica scale. However, in a combustion environment the silica scale reacts with water vapor, a byproduct of combustion, to form a gaseous silicon hydroxide species.