Volume 7 Issue 1, Pages 22 – 29

Wenning N. Liu, Xin Sun, Brian Koeppel, Mohammad Khaleel
Online: Aug 15 2009 1:43AM

DOI: 10.1111/j.1744-7402.2009.02417.x

High operating temperatures of solid oxide fuel cells (SOFCs) require
that the sealant must function at a high temperature between 600°C and
900°C and in the oxidizing and reducing environments of fuel and air.
This paper describes tests to investigate the temporal evolution of the
volume fraction of ceramic phases, the evolution of micro-damage, and
the self-healing behavior of the glass–ceramic sealant used in SOFCs. It
was found that after the initial sintering process, further
crystallization of the glass–ceramic sealant does not stop, but slows
down and reduces the residual glass content while boosting the ceramic
crystalline content. Under a long-term operating environment, distinct
fibrous and needle-like crystals in the amorphous phase disappeared, and
smeared/diffused phase boundaries between the glass phase and ceramic
phase were observed. Meanwhile, the micro-damage was induced by the
cooling down process from the operating temperature to room temperature,
which can potentially degrade the mechanical properties of the
glass/ceramic sealant. The glass/ceramic sealant exhibited self-healing
upon reheating to the SOFC operating temperature, which can restore the
mechanical performance of the glass/ceramic sealant.

Online Access to Journal of Applied Ceramic Technology