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

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-delta appears to be the most promising membrane and substrate material. This material, however, suffers from partial decomposition of cubic structure to hexagonal polymorphs at similar to 825 degrees 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-delta. 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. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.