2ZrO2·Y2O3 Thermal Barrier Coatings Resistant to Degradation by Molten CMAS: Part I, Optical Basicity Considerations and Processing
Abstract
The higher operating temperatures in gas‐turbine engines enabled by thermal barrier coatings (TBCs) engender new materials issues, viz silicate particles (sand, volcanic ash, fly ash) ingested by the engine melt on the hot TBC surfaces and form calcium–magnesium–alumino–silicate (CMAS) glass deposits. The molten CMAS glass degrades TBCs, leading to their premature failure. In this context, we have used the concept of optical basicity (OB) to provide a quantitative chemical basis for the screening of CMAS‐resistant TBC compositions, which could also be extended to environmental barrier coatings (EBCs). By applying OB difference considerations to various major TBC compositions and two types of important CMASs—desert sand and fly ash—the 2ZrO2·Y2O3 solid solution (ss) TBC composition, with the potential for high CMAS‐resistance, is chosen for this study. Here, we also demonstrate the feasibility of processing of 2ZrO2·Y2O3(ss) air‐plasma sprayed (APS) TBC using commercially developed powders. The resulting TBCs with typical APS microstructures are found to be single‐phase cubic fluorite, having a thermal conductivity −1 at elevated temperatures. The accompanying Part II paper presents results from experiments and analyses of high‐temperature interactions between 2ZrO2·Y2O3(ss) APS TBC and the two types of CMASs.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 11, 2014
- Source ID
- 10.1111/jace.13210
Entities
People
- Amanda R. Krause
- Angel L. Ortiz
- Bilge S. Senturk
- Gopal Dwivedi
- Hector F. Garces
- Nitin P Padture
- Sanjay Sampath
Organizations
- Brown University
- Office of Naval Research
- Stony Brook University
- United States Department of Energy
- University of Extremadura