Crystallization behaviour of glass-ceramic sealant for solid oxide fuel cells

• The crystallization behaviour of a glass-ceramic sealant has been investigated by DTA.
• The activation energy for the crystallization and Avrami parameter have been calculated.
• Glass powder size affected the crystallization mechanism and the activation energy for crystallization.

The crystallization behaviour of a glass-ceramic suitable as SOFCs sealant has been investigated using differential thermal analysis (DTA). Glass powders of two different particle sizes (< 38 µm and 38–75 µm) have been considered. The exothermic peak in DTA thermographs has been associated with the crystallization of the diopside phase, as revealed by X-ray diffraction analysis (XRD). Avrami exponents (n) have been calculated for both particle sizes using the Ozawa equation, while Matusita and Sakka equation has been used to calculate the activation energy for the crystallization (Ec). The values found for n are 2.6 (< 38 µm) and 2.1 (38–75 µm). The obtained values for Ec are 403 kJ/mol and 262 kJ/mol for the finest and the coarsest glass powders, respectively. As a comparison, the activation energies for the viscous flow (Eη) have been also evaluated: 349 kJ/mol for powders sized<38 µm and 265 kJ/mol for those sized 38–75 µm.