A low silica, barium borate glass–ceramic for use as seals in planar SOFCs

Abstract A low silica, barium borate glass–ceramic for use as seals in planar SOFCs containing 64 mol%BaO, 3 mol%Al 2 O 3 and 3 mol%SiO 2 was studied. Coefficient of thermal expansion (CTE) between 275–550 °C, glass transition temperature ( T g ), and dilatometric softening point ( T s ) of the parent glass were 11.9 × 10 −6 °C −1 , 552 °C, and 558 °C, respectively. Glass–ceramic was produced by devitrification heat treatment at 800 °C for 100 h. It was found that nucleation heat treatment, seeding by 3 wt%ZrO 2 as glass-composite and pulverization affected the amount, size and distribution of crystalline phases. SEM-EDS and XRD results revealed that crystalline phases presented in the devitrified glass–ceramic were barium aluminate (BaAl 2 O 4 ), barium aluminosilicate (BaAl 2 Si 2 O 8 ) possibly with boron associated in its crystal structure, and barium zirconate (BaZrO 3 ). CTE of the devitrified glass–ceramic was in the range of (10.1–13.0) × 10 −6 °C −1 . Good adhesion was obtained both in the cases of glass and devitrified glass–ceramic with YSZ and AISI430 stainless steel. Interfacial phenomena between these components were discussed.