Mechanical properties of LSCF (La0.6Sr0.4Co0.2Fe0.8O3−δ)–GDC (Ce0.9Gd0.1O2−δ) for oxygen transport membranes

In this study, for application in oxygen transport membranes, an LSCF (La0.6Sr0.4Co0.2Fe0.8O3−δ)–GDC (Ce0.9Gd0.1O2−δ) composite was manufactured, and its mechanical properties were studied. Generally, it is known that LSCF has a nonlinear modulus due to changes in its microstructure when a critical stress is loaded. To improve the mechanical properties of this material, which has a perovskite structure, a study was conducted to evaluate whether its properties change according to the rule of mixtures when it is formed into a composite with GDC. The results showed that the nonlinearity of the modulus of the composite for each specimen composition was largely reduced and stable under fatigue loading. The fracture toughness was superior to that of the LSCF (1.05 MPa m1/2) or GDC (1.28 MPa m1/2) monolithic materials when the composites (1.63 MPa m1/2) was manufactured. The mechanisms for these were explained by finite element analysis and the observation of crack propagation. It was also confirmed that when these composite materials are used for oxygen transport membranes, they show stable properties.