Comparison of thermo-mechanical characteristics of non-doped and 3 mol% B-site Zr-doped Ba0.5Sr0.5Co0.8Fe0.2O3−δ

A dense membrane layer supported by a thick porous substrate is a favorable design for advanced oxygen separation units used in Oxy-fuel processes and membrane reactors. Based on the highest permeation rates verified so far, Ba0.5Sr0.5Co0.8Fe0.2O3−δ appears to be the most promising membrane and substrate material. This material, however, suffers from partial decomposition of cubic structure to hexagonal polymorphs at ∼825 °C, which is associated with a significant oxygen permeation drop. The partial substitution of the B-site with 3 mol% zirconium has been suggested as one of solutions for suppressing this transformation. The current study concentrated on the comparison of the thermo-mechanical characteristics of doped and non-doped Ba0.5Sr0.5Co0.8Fe0.2O3−δ. Although the later material showed higher elastic modulus and fracture strength in absolute values, overall their characteristics mostly agree. It was shown that shortening of the membrane tube from 1 m to half its length should not influence fracture strength significantly. Fractographic analysis ruled out the cutting edge effect in O-ring bending.