High-Temperature Environmental Barrier Coating for Silicon Carbide Composites

SiC/SiC fiber reinforced composites have been developed for use in gas turbine hot sections allowing for increased temperatures and therefore, increased fuel efficiency and lower emissions. A thermally-sprayed functionally-graded thermal/environmental barrier coating is proposed for SiC/SiC composites designed to provide the necessary thermal protection while shielding the SiC/SiC composite from water vapor.  Stresses in the coating system are mitigated through functionally graded layers and through porosity control which allows tailoring of elastic modulus. Materials selection for the various coating layers will consider those which have demonstrated excellent thermal protection and minimal water vapor degradation. BENEFIT: SiC/SiC  fiber reinforced composites have been developed with the goal of increasing combustion gas temperatures, lowering weight and extending the lifetimes of turbine components.  These goals also lead to the additional benefits of reduced NOx and CO2 emissions, higher fuel efficiency, and higher thrust-to-weight ratios for aircraft. The proposed coating technology will increase the durability of ceramic composite engine components exposed to high temperature combustion environments.)