Oxygen Transport Ceramic Membranes

Bandopadhyay, S. ; Nithyanantham, T. ; Zhou, X.-D ; Sin, Y-W. ; Anderson, H.U. ; Jacobson, Alan ; Mims, C.A.

University of Alaska

关键词: Crack Propagation;    Reduction;    Membranes;    Ferrites;    Oxygen;   

DOI  :  10.2172/883083
RP-ID  :  none
RP-ID  :  FC26-99FT40054
RP-ID  :  883083

美国|英语

来源: UNT Digital Library

【 摘 要 】

The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Modeling of the isotopic transients on operating membranes (LSCrF-2828 at 900 C) and a ''frozen'' isotope profile have been analyzed in conjunction with a 1-D model to reveal the gradient in oxygen diffusivity through the membrane under conditions of high chemical gradients.