Chromium Vaporization from Metallic Interconnect and Retention by Perovskite Layers

Abstract

Chromium-bas ed alloys like the oxide-dispersion-strengthened (ODS) alloy Cr5Fe1Y(2)O(3) are suitable materials for the metallic interconnect of solid oxide fuel cells (SOFCs). The vaporization of volatile chromium species from chromium-containing alloys (such as Cr5Fe1Y(2)O(3)) on the cathode side of the SOFC leads to a rapid degradation of the electrical properties of the cell. Acceptor-doped perovskites based on LaCrO(3) are considered as coating materials in order to prevent chromium vaporization from metallic interconnects. In the present paper, the chromium evaporation rate of the uncoated ODS alloy Cr5Fe1Y(2)O(3) is compared with the amount of chromium vaporizing from the La(0.9)Sr(0.1)CrO(3)-coated sample. Chromium vaporization rates were determined by the transpiration method under cathodic SOFC conditions (T = 950 degrees C, p[H(2)O] = 0.02 bar, p[O(2)] = 0.21 bar). Moreover, chromium diffusion coefficients in perovskite layers (La(x)Sr(1-x)CrO(3), La(x)Ca(1-x)CrO(3)) were derived by using a (53)Cr tracer technique.