EBC Development for Hot-Pressed Y₂O₃/Al₂O₃ Doped Silicon Nitride Ceramics

Authors

Sivakumar Ramasamy, Cleveland State University
Surendra N. Tewari, Cleveland State UniversityFollow
Kang N. Lee, Rolls-Royce Corporation
Ramakrishna T. Bhatt, NASA Glenn Research Center
Dennis S. Fox, NASA Glenn Research Center

Document Type

Article

Publication Date

8-20-2010

Publication Title

Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing

Abstract

Multilayer EBCs of alcohol and sol-based slurries containing (a) 45% SiO₂-34% Y₂O₃-%Al₂O₃, (b) mullite/Gd₂SiO₅ (88/12wt.%) with and without B₂O₃ addition, (c) mullite/rare-earth silicates (94/6wt.%, (Gd₂SiO₅, Lu₂SiO₅, Er₂SiO₅, and HfSiO₄)), and (d) only mullite, were applied on hot pressed Y₂O₃/Al₂O₃ doped Si₃N₄ substrates. Of the four major EBC systems studied, only mullite/Gd₂SiO₅ (88/12wt.%) EBCs sintered in air at 1400^oC for 3h showed good bonding with the substrate. In all other EBC systems studied, the Y₂O₃/Al₂O₃ additives present in Si₃N₄ reacted with silica and rare-earth silicates to form low melting point constituents during sintering causing bubble formation and/or de-bonding at the substrate/coating interface. Thermal cyclic resistance of silicon nitride coupons coated with mullite/Gd₂SiO₅ (88/12wt.%) EBC was investigated in a moisture containing environment (90% H₂O-10% O₂) for 100 cycles from 1350^oC to room temperature (1h hot and 15min cold). Moisture exposure resulted in accumulation of large pores in the coating, mostly aligned along the substrate/coating interface.

Repository Citation

Ramasamy, Sivakumar; Tewari, Surendra N.; Lee, Kang N.; Bhatt, Ramakrishna T.; and Fox, Dennis S., "EBC Development for Hot-Pressed Y₂O₃/Al₂O₃ Doped Silicon Nitride Ceramics" (2010). Chemical & Biomedical Engineering Faculty Publications. 61.
https://engagedscholarship.csuohio.edu/encbe_facpub/61

Original Citation

Ramasamy, S., Tewari, S., Lee, K., Bhatt, R., , & Fox, D. (2010). EBC development for hot-pressed EBC development for hot-pressed Y2O3/Al2O3 doped silicon nitride ceramics doped silicon nitride ceramics. Materials Science & Engineering A, 527(21-22), 5492-5498. doi:10.1016/j.msea.2010.05.067

Volume

527

Issue

21-22

DOI

10.1016/j.msea.2010.05.067

Version

Postprint

Publisher's Statement

NOTICE: this is the author’s version of a work that was accepted for publication in Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 527, 21-22, (August 20, 2010) DOI 10.1016/j.msea.2010.05.067