Design and Manufacture of SiC/SiC Nozzle Guide Vanes With Environmental Barrier Coatings for High-Pressure Turbines

Abstract

Increasing the efficiency of jet engines is essential to meet the demanded climate targets. Ceramic matrix composites (CMCs) are strong candidates for aircraft applications because they withstand high temperatures, while their density is two-thirds lower than that of conventional nickel-based alloys. This leads to cooling air savings and a lower overall engine weight, resulting in a potential reduction of emissions. To investigate the potential benefits and manufacturing techniques required for the introduction of CMC to the high-pressure turbine (HPT) of a modern jet engine, the geometry of a nozzle guide vane of an existing turbine was redesigned considering ceramic specific constraints. Then, the liquid silicon infiltration (LSI) process was used to manufacture silicon carbide fiber-reinforced silicon carbide (SiC/SiC) nozzle guide vanes (NGV). Hi-Nicalon S woven fabric was used together with a chemical vapor infiltration (CVI)-based fiber coating. The outer surface of the vane was ground to meet the requirements for surface roughness, and geometric and positional tolerances. Cylindrical, laser-drilled cooling holes were introduced for trailing edge cooling. In the final step, an environmental barrier coating (EBC) system consisting of yttrium disilicate (Y-DS) and yttrium monosilicate (Y-MS) layers was applied using physical vapor deposition (PVD) processing. Wind tunnel testing under technology readiness level (TRL) 4 will be performed and vane performance will be evaluated.