Chemically Modified SiC/SiC for In Situ Growth of Nonvolatile, Environmental Barrier Scale

For significant advancements to occur in the implementation of ceramic matrix composites (CMCs) in aeroengine airfoil applications, silicon carbide (SiC) ceramic matrix that forms corrosion resistant scale is needed for the combustion environment. Particularly troublesome is the accelerated surface oxidation and recession that proceeds due to reaction of the native silica scale with steam in the high-temperature turbine environment. As opposed to the more convention application of environmental barrier coatings (EBC) by plasma spray to meet this challenge, the proposed effort will develop an steam-resistant matrix material for use in SiC/SiC CMCs. More specifically, chemically modified SiC-matrix CMC panels will be fabricated by PIP processing using rare earth-doped polymer precursors. Evaluation of the resulting CMCs will proceed by measuring their oxidation resistance under aggressive, accelerated aging conditions (steam + O2 at high temperatures) that simulate harsh aeroturbine environment. A wide variety of materials property testing will be performed to measure the mechanical effects on the effect of doping the matrix both before and after aging of specimens.