Abstract
More recently a new type of damage has been pronounced in thermal barrier coatings (TBCs) by calcium-magnesium-alumino-silicates (CMAS) from ingestion of siliceous minerals under certain operating conditions. In order to understand material aspect of CMAS damage, a study on material interaction between molten CMAS and yttria-stabilized zirconia (YSZ) was carried out by using a single crystal YSZ material and a synthetic CMAS product in this work. Here the effect of crystallographic orientation on the interaction was also investigated. The CMAS-covered single crystal bulk YSZ specimens were isothermally exposed at high temperature. The experimental works clearly showed that interaction between the molten CMAS and YSZ was significant resulting in the change in microstructural morphology and composition of YSZ. The extent of interaction between CMAS and YSZ depended on the crystallographic plane of the YSZ: it was the lowest in the {111} crystallographic plane.
