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Development and Performance Evaluations of HfO2-Si and Rare Earth-Si Based Environmental Barrier Bond Coat Systems for SiC/SiC Ceramic Matrix CompositesCeramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si based EBC bond coat systems for SiCSiC CMC combustor and turbine airfoil applications are investigated. The coating design approach and stability requirements are specifically emphasized, with the development and implementation focusing on Plasma Sprayed (PS) and Electron Beam-Physic Vapor Deposited (EB-PVD) coating systems and the composition optimizations. High temperature properties of the HfO2-Si based bond coat systems, including the strength, fracture toughness, creep resistance, and oxidation resistance were evaluated in the temperature range of 1200 to 1500 C. Thermal gradient heat flux low cycle fatigue and furnace cyclic oxidation durability tests were also performed at temperatures up to 1500 C. The coating strength improvements, degradation and failure modes of the environmental barrier coating bond coat systems on SiCSiC CMCs tested in simulated stress-environment interactions are briefly discussed and supported by modeling. The performance enhancements of the HfO2-Si bond coat systems with rare earth element dopants and rare earth-silicon based bond coats are also highlighted. The advanced bond coat systems, when integrated with advanced EBC top coats, showed promise to achieve 1500 C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and long-term durability.
Document ID
20140008956
Acquisition Source
Glenn Research Center
Document Type
Presentation
Authors
Zhu, Dongming
(NASA Glenn Research Center Cleveland, OH United States)
Date Acquired
July 10, 2014
Publication Date
May 2, 2014
Subject Category
Chemistry And Materials (General)
Report/Patent Number
GRC-E-DAA-TN14696
Meeting Information
Meeting: International Conference on Metallurgical Coatings and Thin Films
Location: San Diego, CA
Country: United States
Start Date: April 28, 2014
End Date: May 2, 2014
Sponsors: American Vacuum Society
Funding Number(s)
WBS: WBS 794072.02.03.03.02.02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
HfO2-Si bond coat
Rare earth-Si bond coat
Environmental barrier coatings
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