Subcritical Crack Growth Behavior of A Perovskite-Type Oxygen Transport Ceramic Membrane

We herein report subcritical crack growth (SCG) studies of La0.2Sr0.8Fe0.8Cr0.2O3-delta (LSFCO) perovskite membranes as oxygen transport membranes (OTM). Two sample batches of perovskite were tested to investigate the effect of temperature, specific chemical environments, and loading rate on flexure strengths, using four-point bend tests. The first batch was examined at room temperature in air. The second batch was soaked in an N-2/air atmosphere at 1000 degrees C. Stress rates varied approximately from 0.2 to 90 MPa/s. The strength-probability-time diagram is constructed for design proposes. Flexural strength data indicate that the examined OTM material showed little susceptibility to SCG at room temperature in air. However, the sample is susceptible to SCG in an N-2/air environment at 1000 degrees C. Also, the experiments demonstrate flexural-strength rate dependency, with strength increasing with the stress rate. The observed phenomena are explained by the decomposition and microstructural transitions in the perovskite.