Optimization of the synthesis route of a barium boron aluminosilicate sealing glass for SOFC applications

A barium boron aluminosilicate sealing glass for IT-SOFC or SOFC applications was synthesized using different routes. Notably, sol-gel and solid state processes were used in order to obtain homogeneous glasses at 1100-1300 °C. Sol-gel processes consist in a soft chemistry route allowing a better homogeneity between cationic precursors in the mixture and a better reactivity of the material. The influence of the process and of the glass processing temperature on the thermo-mechanical properties of the glasses were investigated after different heat treatments in air atmosphere, i.e. glass processing, sealing (850 °C-2 h) and ageing (800 °C-100 h) procedures. It had been observed that the grain size of the glass powder (obtained after the glass processing and used for the sealing operation) is determining in order to manage the sealing procedure. Some large pores were formed during the devitrification step of the glass made by solid state route while glass sealants synthesized by the sol-gel route even at 1100 °C remained suitable for SOFC applications after thermal treatments, which proved that the sol-gel process is useful to decrease the glass processing temperature.