Microstructure of zirconia-yttria plasma-sprayed thermal barrier coatings

The objective of this paper is to report on the characterization of the highly complex microstructure of zirconia coatings, which arise as a result of the plasma-spraying process. The fine structure has been observed to change through the thickness of the coating, behaviour which has been related to the cooling rate and crystallization of the deposited material. Microstructural features such as an amorphous bond coat/ceramic interfacial film and a grain-boundary glassy phase, which are believed to have a significant effect upon coating properties such as adhesion and compliance, have been shown to be present.