Mechanical and thermophysical properties of thick PYSZ thermal barrier coatings: correlation with microstructure and spraying parameters

The thermophysical and mechanical properties of plasma-sprayed thermal barrier coatings are very strongly dependent on the microstructure, and this may be controlled by manipulating the parameters controlling the plasma spray process. A series of coatings was produced by plasma spraying ZrO 2+8wt%Y 2O 3 (PYSZ) to a thickness of about 2 mm, some six to eight times thicker then state of the art coatings currently in service. A controlled variation of plasma spray parameters was carried out to produce a range of different microstructures that could be related to material properties and these in turn correlated with the process variables. The particular properties studied were the thermophysical properties, diffusivity and expansion, and the mechanical properties, modulus, strain to failure and flexural strength measured in four point bend.