Improved Erosion / Impact Resistant Environmental Barrier Coatings for SiC-CMC’s

MRi is teaming with Ohio Aerospace Institute and Exotherm Corporation to conduct innovative processing developments to improve the erosion and impact performance of environmental barrier coatings for SiC/SiC high temperature composites. The effort will be to both improve the bond coat layer and to improve the structure of Mullite +BSAS inner layer and the top layers using SHS prepared powders of ( HfO2+ ScO3) in combination with plasma spraying. CMCs such as SiC/SiC are porous so infiltration can lead to degradation of EBC’s associated with oxidation of the interface coating, as opposed to the moisture induced matrix erosion which is the primary problem in the higher temperature applications referenced above. The core of our proposed effort will aim to improve bond coats with dual layer bond layers that bond better to the SiC/SiC and prevent low temperature glasses forming at the mullite interface. The effort will also investigate the improvement of the structure of Mullite +BSAS and the top layers of (HfO2+ ScO3) using reaction synthesis (SHS) prepared powders of in combination with plasma spraying. After developing new composition and structure of bond coat and the top coat, SiC/SiC coupons will be coated and tested including mechanical property measurements after 100 hours of exposure to intermediate temperature and after cyclic humidity and high temperature exposures. Investigator between Phase I and I Option will also evaluate erosion and impact resistance of the more promising EBC compositions.