Opportunities for improved TBC durability in the CeO2-TiO2-ZrO2 system

A previously unreported, relatively large single-phase tetragonal field with exceptional tetragonality has been stabilized up to at least 1350 degrees C by co-doping zirconia (ZrO2) with ceria (CeO2) and titania (TiO2). The tetragonality is believed to be responsible for an increase in micro-indentation toughness, relative to traditional 7YSZ, based on activation of ferroelastic domain switching. Evidence consistent with this toughening mechanism has been directly observed via transmission electron microscopy (TEM). Within grains >5 mu m, long-range anion order is induced within elastically switched domains. This observation provides additional insight on the toughening mechanism. In the absence of stoichiometric anion vacancies, the large non-transformable tetragonal composition range and the improved toughness suggest that this system could be a promising option for next generation thermal barrier coatings. (C) 2013 Elsevier B.V. All rights reserved.