Characterization of a barium–calcium–aluminosilicate glass/fiber glass composite seal for intermediate temperature solid oxide fuel cells

The properties of BaO–CaO–Al₂O₃–SiO₂ (BCAS) glass seal materials reinforced with 5–30 wt.% glass fiber are investigated. The seals are prepared by solid mixing process. The microstructure and phase content of the samples are studied. Mechanical properties are investigated by Vickers micro-hardness, nano-indentation and compression tests. The thermal properties of the samples are evaluated by conducting a dilatometry analysis. The electrical conductivity and leak resistance of the seal materials are measured at high temperatures. Increasing the amount of glass fiber in the composite samples decreases the magnitude of the thermal expansion coefficient. It is found the addition of just 5 wt.% of glass fiber (GF5sample) increases the indentation fracture toughness of the seals by ∼280% without impairing other properties. It is also found that the GF5 sample has high electrical resistivity with the activation energy of 63.7 kJ/mol and very low leak rate of 1.7 × 10⁻⁴ sccm/cm at 750 °C.