Chromium vaporization of bare and of coated iron–chromium alloys at 1073 K

Abstract

Suppression of chromium vaporization from oxidation scales formed on ferritic stainless steel, when used on the cathode side of Solid Oxide Fuel Cells (SOFC), is a most important issue, since gaseous chromium species cause deposition of chromium oxide on electrolyte or electrode materials. This phenomenon leads to deterioration of the cell performance. The chromium vaporization rates of bare and of coated iron–chromium alloys were measured at 1073 K. The effect of ceramic coating layers, deposited by low-cost aerosol spraying or by dip coating, was evaluated and the morphology of the coating layer was observed. Lanthanum strontium manganese oxide (LSM: La 0.65Sr 0.3MnO 3), lanthanum strontium cobalt iron oxide (LSCF: La 0.6Sr 0.4Co 0.8Fe 0.2O 3) and manganese cobalt oxide (MCO: MnCo 2O 4) coatings, formed from submicron powders, decreased chromium vaporization by a factor of as much as 21–40 at 1073 K. Manganese cobalt oxide and lanthanum strontium chromium oxide (La 0.7Sr 0.3CrO 3) coating, formed from powders prepared by a glycine nitrate combustion synthesis, reduced chromium vaporization by factors of only 2–3 because the coating layers were porous.