Crystallization kinetics and phase transformation of glass-ceramic seals for solid oxide fuel cell application

The crystallization behavior of glass-ceramic seals for solid oxide fuel cells (SOFC) applications was investigated using thermal analysis. Two kinds of glass-based seals H1-20 and H4-20 were formulated by adding 20 wt% YSZ (Y2O3 stabilized ZrO2) powder into two powdered glasses H1 and H4. The results showed that the two seals can inhibit uncontrolled deformation and maintain structure integrity at SOFC operation temperatures. The Avrami parameters (n) calculated for the seals H1-20 and H4-20 are 3.2 and 2.6, respectively, and the respective activation energies (Ec) of crystal growth calculated are 17.2 kJ/mol and 32.7 kJ/mol. These crystallization kinetic parameters are consistent with the results of the phase transformation analyses for the two seals at 750 °C, suggesting that the thermal stability of the seal H4-20 was higher than that of the seal H1-20. Furthermore, the microstructure of the two seals were characterized using XRD and TEM, and the results suggest that the seal H4-20 is a promising candidate for long-term SOFC stack applications.