Microstructure and phase composition of ZrO2-Ce02thermal barrier coatings
P. D. HARMSWORTH, R. STEVENS
JOURNAL OF MATERIALS SCIENCE
abstract:The microstructure and phase composition of zirconia plasma-sprayed thermal barrier coatings containing 12 to 25 wt% ceria addition have been investigated. Coatings containing less than 20 wt % Ce02 are composed of a monoclinic and retained metastable transformable tetragonal phase due to the constraint developed by the small crystal size. This phase transforms readily under moderate thermal stresses. Compositions greater than 20 wt% Ce02 are composed only of a metastable non-transformable tetragonal, tz' structure, resistant to transformation under thermal or mechanical stresses. The microstructure of this phase shows microstructural similarities to the high-yttria f-phase in the ZrOz-Y203 system, such as transformation twins and anti,phase boundaries. This suggests that the phase observed in the ZrO2-Ce02 system forms by a similar mechanism.
keywords:coatings containing; tetragonal phase; similarities; ZrOz; barrier coatings; wt ceria
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