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High temperature mechanical behavior of porous ceria and ceria‐based solid‐oxide fuel cells
Author(s) -
Stanley Patrick,
Hays Thomas,
Langdo Tom,
Gore Colin,
Wachsman Eric D.
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16398
Subject(s) - materials science , porosity , solid oxide fuel cell , flexural strength , composite material , microstructure , thermogravimetric analysis , scanning electron microscope , oxide , compressive strength , anode , chemical engineering , metallurgy , chemistry , electrode , engineering
Multiple environment mechanical testing of solid‐oxide fuel cells (SOFCs) and SOFC materials is critical to ensure appropriate compressive sealing in stack designs. Establishing the effects of temperature, environment, and porosity on the flexural strength of ceria‐based SOFCs is a significant step toward practical deployment of the technology. This article presents research into these properties by use of a temperature and atmosphere controlled 3‐point bend fixture capable of reaching Intermediate Temperature (IT)‐SOFC operating conditions (650°C). Gadolinium‐doped ceria (GDC) samples with varying porosity and pore geometry were tested and it was determined that more spherical porosity contributed to improved flexural strength as compared with higher aspect ratio porosity. A linear strengthening effect was also observed with increasing temperature from ambient to 650°C for GDC‐based anode support layers and half‐cell samples. Scanning electron microscopy was performed on fracture surfaces to identify fracture modes and to examine internal pore structures. Directionality of the applied stress with respect to the layered microstructure was found to have no measurable impact on mechanical properties in air, but orientation had a significant impact on strength of cells with reduced anodes. Additionally, with the support of thermogravimetric analysis, it was determined that after reduction, exposure to oxygen below 100°C does not influence mechanical properties of the cells.