SiO2–CaO–B2O3–Al2O3 ceramic glaze as sealant for planar ITSOFC

A series of ceramic glazes based on the SiO2–CaO–B2O3–Al2O3 system as sealant for intermediate temperature solid oxide fuel cell (ITSOFC) were investigated. Different ratios of B2O3/SiO2 and Al2O3/CaO were investigated to control softening process, phase separation, and crystallization. When B2O3/SiO2 ratio was in the range of 0.14–0.27, the glazes showed good wetting and bonding behavior with both 8 mol% yttria-stabilized zirconia (8YSZ) electrolyte and stainless steel interconnect which could satisfy the sealing demand at 850 °C. And the dimension stability can be kept for over 100 h by introducing ceramic felt and controlling the glazes viscosity in the range of 104 to 106 Pa s. By means of controlling Al2O3/CaO ratio in the range of 0.4–0.68, phase separation and crystallization were restrained effectively. After holding at 850 °C for 100 h, non-crystalline network in the glazes could be found, and a suitable viscous flow could well relax thermal stress. The sealing was effective even after 10 thermal cycles. Element analysis showed a good chemical stability at the ceramic glazes/stainless steel interconnect and ceramic glazes/8YSZ electrolyte interfaces.