Thermal Shock Resistance of Yb₂SiO₅/Si and Yb₂Si₂O₇/Si Coatings Deposited on C/SiC Composites

Abstract:

Rare-earth silicates, especially ytterbium silicate (Yb₂SiO₅ and Yb₂Si₂O₇), have been developed for promising environmental barrier coatings (EBCs) for SiC-matrix composites. In this study, double-layer Yb₂SiO₅/Si and Yb₂Si₂O₇/Si EBC systems were deposited on C/SiC composites by air plasma spray (APS) technique, respectively. Both systems were subjected to thermal shock tests at 1400 °C. The evolution of phase composition and microstructure of those samples before and after thermal shock test were characterized. Results showed that there were penetrating microcracks in the top Yb₂SiO₅ layer and horizontal microcracks at the Yb₂SiO₅-Si interface after thermal shock test. While extremely few microcracks and no horizontal microcracks were presented in the Yb₂Si₂O₇/Si sample. The EDS analysis also showed that the Si bond layer of the Yb₂SiO₅/Si sample was oxidized more serious than that of the Yb₂Si₂O₇/Si sample. The different thermal shock behaviors of both systems were clarified based on the thermal expansion behavior, phase composition and microstructure analysis.

• Periodical: Solid State Phenomena (Volume 281)
• Pages: 472-477
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.281.472
• Online since: August 2018
• Authors: Xin Zhong, Ya Ran Niu*, Tao Zhu, Hong Li, Xue Bin Zheng, Jin Liang Sun
• Keywords: Air Plasma Spray, Environmental Barrier Coating, Thermal Shock Resistance, Yb₂Si₂O₇, Yb₂SiO₅

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