|About this Abstract
|MS&T23: Materials Science & Technology
|Advanced Coatings for Wear and Corrosion Protection
|Benefits of Yttria-doping in Ytterbium Disilicate Environmental Barrier Coatings
|Dawson Smith, Vincent Mika, Molly O'Connor, Robert Golden, Rodney Trice, Michael S. Titus
|On-Site Speaker (Planned)
|Michael S. Titus
Ytterbium disilicate (YbDS) and yttria-doped ytterbium disilicate environmental barrier coatings protect ceramic matrix composite components in gas turbine engines from corrosive atmospheres. When deposited by atmospheric plasma spray, the coatings are partially amorphous, metastable, and exhibit numerous cracks. Thus, the coatings require a pre-service heat treatment to crystallize and, ideally, heal pre-existing cracks. In this study we determine the phase transformation kinetics, temperatures, and volumetric changes using a combination of differential scanning calorimetry and dilatometry. These results suggest multiple phase transformations occur during simulated heat treatments, and we validated these transformations using correlative Raman and scanning electron microscopy. Experimentally measured thermo-physical properties were integrated into a finite element model to predict the Stress evolution in the coating during heat treatments. In this work, we will present new heat treatments that reduce processing time while adequately healing pre-existing cracks, and we will elucidate the beneficial role of Y-doping in YbDS coatings.