In-situ Synchrotron X-ray diffraction Volcanic Ash Infiltration Studies on High Temperature Ceramic Coatings

Abstract

Calcium-magnesium-alumino-silicate (CMAS) particulates, such as sand or volcanic ash (VA), are ingested by aero-engines and negatively interact and degrade high temperature ceramic coatings. These ceramic thermal barrier coatings (TBCs) are used to protect temperature sensitive metallic components, such as turbine blades, from melting due to the extreme temperatures of the hot gas streams formed from the combustor of the engine. In this work, in-situ synchrotron X-ray diffraction measurements were used to capture the interaction and subsequent degradation of a 7 wt% yttria-stabilized zirconia TBC from a VA CMAS composition. In-situ methods have the ability to a greater insight into the mechanisms dominating infiltration as well as capture data regarding the interactions of CMAS and the TBC while in a molten state and upon CMAS solidification while in representative environmental conditions in a controlled laboratory setting. Changes in the bi-axial e11 and e22 strains as well as the formation of new rings, indicative of VA and 7YSZ interactions during infiltration. These results demonstrate the capabilities to capture highly resolved CMAS and coating interactions during operation which is important for capturing, evaluating, and elucidating potential CMAS mitigation strategies.