The effect of process stress evolution on the microstructure of plasma sprayed zirconia coatings

摘要

Yttria stabilized zirconia (YSZ) coatings fabricated by atmospheric plasma spray (APS) have long been applied as thermal barriers on hot section components of gas turbines and jet engines. These APS YSZ coatings have complex, layered, defected microstructures which are greatly influenced by by numerous spray parameters. Optimizing and control of these defected microstructures are not only necessary both for coating durability but also an opportunity for tailoring the microstrucure. In recent years, the microstructural assemblage of the coating has been expressed through complex non-linear elastic descriptions, however, the role of intrinsic stresses as well as adhesion on the durability requires further interpretation. In this study, residual stresses of YSZ coatings during deposition were measured by means of in-situ curvature monitoring method. The measured stresses may offer insights into the microstructuers. Furthermore, the interfacial fracture toughness of coatings were obtained by indentation test. Such quantitative measurements of mechanical properties can further enhance the understanding of the coated system, microstructures and processing influences.