Study on expansion characteristics of Al-Al2O3 composite seals for intermediate-temperature solid oxide fuel cell

Al2O3-based composite seal with 10 wt% Al powder addition (A10) possesses excellent plastic and mechanical performance under wide temperature range of solid oxide fuel cell. The thickening phenomenon of A10 seal between 250 degrees C-400 degrees C and 600 degrees C-750 degrees C is caused by the thermal expansion of organic additives and the volume expansion when solid-liquid Al react with oxygen to form Al2O3. The thickness change rate reaches the maximum which is about 5% at 300 degrees C and is about 4.46% at 650 degrees C. The Gibbs free energy for reaction between Al and Al2O3 in the temperature range of 523-1 023 K is all less than 0, which is proved by the fact that A10 exhibits excellent self-expansion and thermodynamic properties in the solid oxide fuel cell operating temperature.