Understanding the thermal barrier performance of plasma-sprayed rare-earth zirconate coating against volcanic ash ingestion

Abstract

Plasma sprayed thermal barrier coatings (TBC) are widely used to protect gas turbine engine components typically exposed to different types of failures. The state-of-art yttria-stabilized-zirconia (YSZ) TBC fails above 1150 °C under calcium‑magnesium-alumino-silicate (CMAS) or volcanic ash (VA) infiltration and associated thermal cyclic degradation. Rare earth zirconate (REZ) is considered a potential candidate TBCs to perform at much higher temperatures and exhibit better CMAS infiltration resistance. Advanced REZs such as gadolinium zirconate (Gd2Zr2O7, GZ) and yttrium zirconate (Y2Zr2O7,YZ) were chosen for the present study. Free-standing coatings of REZ were deposited by atmospheric plasma spray (APS) and assessed for their VA interaction behavior at elevated temperatures (1150 °C/1250 °C). Single-layered (SL) and double-layered (DL) TBC systems were deposited on superalloy substrates to assess the thermal cycling performance. From the studies, Plasma-sprayed REZ TBCs demonstrate enhanced resistance toward CMAS infiltration and thermal cycling degradation at simulated test conditions, thereby qualifies for futuristic high-performance TBC applications.