| About this Abstract |
| Meeting |
MS&T22: Materials Science & Technology
|
| Symposium
|
High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond III
|
| Presentation Title |
Design of Multicomponent Rare-earth Sesquioxides for Thermal/Environmental Barrier Coatings |
| Author(s) |
Kristyn D. Ardrey, Mahboobe Jassas, Mukil Ayyasamy, Kang Wang, Kevin Reuwer, Jonathan Laurer, Carolina Tallon, Bi-Cheng Zhou, Prasanna Balachandran, Patrick Hopkins, Elizabeth Opila |
| On-Site Speaker (Planned) |
Elizabeth Opila |
| Abstract Scope |
Refractory alloys, such as Nb-base C-103, are susceptible to rapid oxidation thereby requiring environmental barrier coatings (EBCs). New coating concepts utilize “high entropy” rare-earth oxide (HERO) mixtures to achieve requisite coating properties, as follows. Cubic phase rare earth (RE) sesquioxides (RE2O3) are desired for a good thermal expansion match to C-103. RE2O3 are high-temperature steam stable. Large RE cations readily form apatite barrier layers during reaction with molten calcium magnesium aluminosilicates, common contaminants in turbine engines. Oxygen diffusivity in Y2O3 is orders of magnitude lower than that in yttria stabilized zirconia. Combinations of RE cations in RE2O3 with large mass and size variation reduce thermal conductivity due to increased phonon scattering. Nb and RE2O3 have a stable interface due to the significantly higher stability of RE2O3 relative to Nb-oxides. RE2O3 mixtures synthesized by slurry or atmospheric plasma spray that simultaneously optimize EBC properties for refractory alloys will be described. |