Yttria-doped zirconia plasma-sprayed thermal barrier coatings (TBC’s) have been used successfully to improve the performance and extend the life of industrial equipment such as jet engines. For this reason, there is considerable interest in understanding and improving the plasma spray process and resulting TBC’s. A collaborative research program exists between Sandia National Laboratories and the National Institute of Science and Technology (NIST) to study the materials and processes used in preparing the coatings as well as the relationship between the physical properties of the coating and its microstructure.

The purpose of this work was to determine the elemental compositions on a micrometer scale of an yttria-doped zirconia coating. The cubic and tetragonal crystal forms of the yttria-doped zirconia have the most favorable thermal expansion coefficient, therefore providing the most effective thermal barrier. The Y concentration in these crystal phases is known to be 6-7 wt%, while the less desirable monoclinic phase, having a less favorable thermal expansion coefficient, contains less that 3 wt% Y.