|About this Abstract
|MS&T23: Materials Science & Technology
|Phase Transformations in Ceramics: Science and Applications
|Progress on Phase Stability of Substituted Rare Earth Disilicate Compositions for Environmental Barrier Coatings
|Christine Brockman, V. V. Rohit Bukka, Amjad S. Almansour, Pankaj Sarin
|On-Site Speaker (Planned)
Environmental barrier coatings (EBCs) enable the use of ceramic matrix composites (CMCs) in turbine engine components by protecting the CMC from oxidation and recession in extreme environments. Rare earth (RE) disilicates have been used as an EBC topcoat layer to slow the degradation of underlying EBC layers. Y2Si2O7 is a promising material, but the presence of polymorphs at high temperatures limits its usage. A method to stabilize Y2Si2O7 has been investigated, through the substitution with another RE material, scandium. Compositions of (YxSc1-x)2Si2O7 systems with increasing Sc content at the RE site were synthesized at 1100°C. X-ray diffraction (XRD) was used to confirm the α-phase of Y2Si2O7, and β-phase for each (YxSc1-x)2Si2O7 system (6, 13, 21 mol% Sc) after synthesis. Results from high temperature XRD will be presented to elucidate the phase stability, phase transformation and anisotropic thermal expansion properties of each (YxSc1-x)2Si2O7 system as a function of composition and temperature.