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| Abstract No.: |
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Scheduled at:
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Thursday, May 05, 2022, Hall D 11:40 AM
Industrial Gas Turbines
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| Title: |
Effect of plasma flame chemistry on the in-situ decomposition of next-generation environmental barrier coatings
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| Authors: |
Edward Gildersleeve / Stony Brook University, United States of America
Eugenio Garcia-Granados / Center for Thermal Spray Research, USA
Sanjay Sampath*/ Stony Brook University, USA
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| Abstract: |
Aerospace Gas Turbine Engine technology has followed a continuous trend of increasing inlet temperatures in the hopes of improving operating efficiency. As such, the goal of increasing operating temperatures can result in component surface temperatures upwards and above 1350C. Thus, it is not plausible to continue using conventional superalloy/bond coat/Thermal Barrier Coating (TBC) stacked structures due to substrate and coating instabilities.
Thus, the next-generation system for the Gas Turbine Engine is set to include a SiC-SiC Ceramic Matrix Composite (CMC) substrate with a protective overlay coating to prevent the combustion environment inducing water vapor volatilization of the CMC. The current state-of-the art of such Environmental Barrier Coatings (EBCs) are currently being envisioned as rare earth (RE) silicate ceramic coatings. Of particular interest is the Ytterbium Disilicate Yb2Si2O7 (YbDS) system. In this study, YbDS EBC coatings were produced on Hexoloy sintered SiC substrates coated with Si bond coat by Air Plasma Spray (APS) – while modulating the processing conditions. This study specifically focuses on the deleterious decomposition of YbDS during APS Processing and the effect of plasma chemistry on that decomposition. Plasma spray parameters using the SinplexProTM Cascaded Plasma Torch for both Ar-H2 and Ar-He plasmas were developed in order to match particle temperature, velocity, and melt state. The resulting coatings were evaluated for their unique characteristics as a consequence of the processing. It was found that the plasma gas chemistry has a remarkable effect on the final composition of the APS YbDS coatings and their thermomechanical properties.
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