Ceramic Matrix Composite Materials for Engine Exhaust Systems on Next-Generation Vertical Lift Vehicles

Abstract

Future gas turbine engines will operate at significantly higher temperatures (∼1800 °C) than current engines (∼1400 °C) for improved efficiency and power density. As a result, the current set of metallic components (titanium-based and nickel-based superalloys) will be replaced with ceramics and ceramic matrix composites (CMCs). These materials can survive the higher operating temperatures of future engines at significant weight savings over the current metallic components, i.e., advanced ceramic components will facilitate more powerful engines. While oxide-based CMCs may not be suitable candidates for hot-section components, they may be suitable for structural and/or exhaust components. However, a more thorough understanding of the performance under relevant environment of these materials is needed. To this end, this work investigates the high-temperature durability of a family of oxide–oxide CMCs (Ox–Ox CMCs) under an engine-relevant environment. Flat Ox–Ox CMC panels were cyclically exposed to temperatures up to 1150 °C, within 240 m/s (∼0.3 M) gas flows and hot sand impingement. Front and backside surface temperatures were monitored by a single-wavelength (SW) pyrometer and thermocouple, respectively. In addition, an infrared (IR) camera was used to evaluate the damage evolution of the samples during testing. Flash thermography nondestructive evaluation (NDE) was used to elucidate defects present before and after thermal exposure.