Slow Crack Growth Analyses of Oxygen Transport Ceramic Membranes

Abstract

AbstractPerovskite-type oxides are promising materials with potential use as dense membranes for oxygen separations. We herein report slow crack growth (SCG) studies of La0.2Sr0.8Fe0.8Cr0.2O3-δ (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 bending tests. The first batch was examined at room temperature in air. The second batch was soaked in a N2/air atmosphere at 1000°C for 1 hour prior to application of load. Loading rates varied from 0.00005 mm/s to 0.01 mm/s. 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 a N2/air environment at 1000°C. Also, the experiments demonstrate flexural-strength rate dependency, with strength increasing with the loading rate. The observed phenomena are explained by the decomposition and microstructural transitions in the perovskite. The results provide important information about OTM mechanical degradation, which is valuable for future OTM design applications.