Development and validation of high performance thick Thermal Barrier Coating (TBC) for application on turbine components

This paper addresses the development of thick TBC, focusing attention on the microstructure and the porosity of the Yttria Partially Stabilized Zirconia (YPSZ) coating, in relation to its resistance to thermal cycling fatigue. Thick TBC coatings, with different grade of porosity, were produced by means of a CoNiCrAlY bond coat and YPSZ top coat, both sprayed by Air Plasma Spray. Top coat layers with different porosity with an average thickness of 1.8 mm were coated. Finally the samples have been submitted to thermal cycling fatigue (FCT) test, according to the procedure of two important OEMs. All the samples passed FCTs according the OEMs protocols. The limit of the thermal fatigue resistance increases with amount of porosity in the top coat.