The ferritic stainless steel Crofer 22 APU is attractive for the use as interconnects in solid oxide fuel cell stacks. The oxidation rate of this alloy in air at 800 °C was reduced by pre-oxidation at higher temperatures in either air or N2-9%H2-1%H2O. Conversely, the oxidation rate increased when the alloy grain size was increased by heat-treating in H2 (pO2 ∼ 10−21 atm). In all cases the scale formed on Crofer 22 APU consisted of an outer (Mn,Cr)3O4 layer, an inner Cr2O3 layer and sub-scale MnCr2O4 nodules that preferentially formed at alloy grain boundaries.
- Stainless steel
- High temperature corrosion