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6559 |
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Wednesday, June 10, 2020, Hall D 12:10 PM Aviation Industry I |
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Evaluation of next generation rare earth silicate EBC coatings
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Alain Allimant* / Saint-Gobain C.R.E.E., France Tim Vitorino / Saint-Gobain, USA |
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In order to increase fuel efficiency of jet engines, ceramic matrix composites (CMC) have been introduced into new designs. Silicon based CMCs enable higher service temperatures and reduced weight, which translates into reduced fuel consumption and emissions. These CMCs, however, face steam-induced corrosion that must be mitigated by using a protective Environmental Barrier Coating (EBC). Saint-Gobain has long history of developing such EBC materials as powders for thermal spraying. The first generation BSAS-based coatings have evolved to current rare-earth (RE) mono- and di-silicates. Specially designed fusion processes have been improved over the years to provide the most uniform powders both in terms of chemistry and phase. Yttrium and Ytterbium disilicates have become a widely used reference material for studies and new developments. More recently interest has increased for Scandium silicates. These powders have been developed and thermally sprayed on silicon based substrates for evaluation. We will compare the features of these powders in the coating process and investigate the as-sprayed and heat-treated coatings. Water vapor corrosion tests will be presented to quantify the protection afforded by Scandium disilicate versus other more common solutions. Preliminary CMAS exposure tests will be shown and an outlook on additional tests to be completed on CMAS resistance will be presented. |