Destabilization of Zirconia Thermal Barriers in the Presence of V 2 O 5

Impurities, such as vanadium, degrade the operating performance of yttria‐stabilized zirconia thermal‐barrier coatings. V 2 O 5 reacts preferentially with Y 2 O 3 , forms YVO 4 , and leads to the destabilization of zirconia thermal‐barrier material. A model experiment has been designed to monitor the destabilization of zirconia thermal barriers by directly exposing thin films of yttria‐stabilized zirconia to V 2 O 5 vapor. The growth of YVO 4 from yttria‐stabilized zirconia and the destabilization of cubic yttria‐stabilized zirconia into tetragonal and/or monoclinic zirconia polymorphs are monitored by selected‐area diffraction and energy‐dispersive X‐ray spectroscopy in the transmission electron microscope. A special crystallographic orientation relation between YVO 4 and cubic zirconia is discussed.