Cr evaporation of metallic interconnects: A novel method for quantification

Paper in proceeding, 2009

Chromium evaporation from metallic interconnects in SOFCs is commonly poisoning the cathode of SOFCs. To reduce chromium evaporation, rather thick coatings have been deposited using various coating techniques. In this study, a 22% Cr ferritic steel has been coated with thin films (<1?m) of metallic cobalt. The Cr evaporation measurements are carried out with a denuder technique which allows time resolved quantification of volatile chromium species. Downstream of the samples a denuder tube is placed which collects any CrO 2(OH)2 evaporating from the samples. The experiments are carried out at 850°C in a N2-20%O2-3%H2O atmosphere. The investigated Co coatings proved to be very efficient and reduce the Cr evaporation by approximately 90%. Microscopic studies show that both coated and uncoated samples develop two-layered oxide scales with the bottom part consisting of Cr-rich corundum type oxide. The uncoated samples develop a top layer consisting of (Cr,Mn)3O4 oxide while the Co coated samples exhibit atop layer consisting of (Co,Mn)3O 4.