Oxidation study of porous metal substrates for metal supported proton ceramic electrolyzer cells

Isothermal corrosion of coated and uncoated porous, ferritic stainless steel (Hoganas), with 20.6 wt% Cr and 30-35 % porosity, has been studied at temperatures from 600 to 800 degrees C in air and 2.5 %H2O/5 %H-2/Ar. Uncoated specimens form protective Cr2O3 scales following parabolic kinetics at 600 and 700 degrees C in air and at 800 degrees C in 2.5 %H2O/5 %H-2/Ar. Non protective scales were formed in 2.5 %H2O/5 %H-2/Ar at 600 and 700 degrees C and at 800 C in air. The coating overall improves the corrosion behavior. The scaling behavior was explained from Fe-Cr-O-2 stability diagrams and ratios between consumption and feed of Cr at the alloy-oxide interface.