Effect of pre-oxidation on the oxidation resistance of Crofer 22 APU. (1st July 2018) - Talic, Belma
Highlights: Oxidation rate of Crofer 22 APU can be reduced by higher temperature pre-oxidation. Increasing the alloy grain size increases the oxidation rate of Crofer 22 APU. Sub-scale MnCr2 O4 nodules form preferentially at alloy grain boundaries. Abstract: 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%H2 O. 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)3 O4 layer, an inner Cr2 O3 layer and sub-scale MnCr2 O4 nodules that preferentially formed at alloy grain boundaries.