Non-linear elastic properties of plasma-sprayed zirconia coatings and associated relationships with processing conditions

Low-temperature thermal cycling of plasma-sprayed zirconia coatings via curvature measurements revealed their in-plane non-linear behavior. This feature arises from the unique layered, porous and cracked morphology of thermal-sprayed ceramic materials. The non-linear aspect can be quantified by a novel data interpretation procedure consisting of modified beam bending analysis and inverse analysis. This versatile procedure requires minimum measurement preparation and computational effort, and its non-linear model enables correct data interpretations otherwise not possible with the previous assumption of linear elastic models. Using this procedure, various specimens were tested to investigate the effects of processing conditions. Results are interpreted in the context of microstructural changes in the plasma-sprayed coatings due to differences in particle state upon impact and coating build-up. The implications of this study are significant for the thermo-mechanical design of strain-tolerant ceramic coatings in thermal barrier applications. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.