Effects of alloyed La, Cu and B on the oxidation of Fe-22Cr ferritic stainless steels under simulated cathode side atmosphere of solid oxide fuel cell interconnects

Abstract

Discontinuous oxidation of La (0.14&#8211

0.52 wt.%), Cu (0.17&#8211

1.74 wt.%) and B (48&#8211

109 ppm) alloyed Fe-22Cr ferritic stainless steels, and Crofer 22 APU (0.047 wt.% La), have been studied at 800 °C, in flowing air-2% H2O atmosphere, for 1300 h. The determined parabolic rate constants (1.65&#8211

2.58×10-4 mg2 cm-4 h-1) are quite close to each other. Benefits of high La-alloying are not caused by the reduction in oxidation, but rather by the alteration in scale growth direction. On the other hand, high Cu-alloying promotes the segregation of Cu at the scale/alloy interface, which suppresses the sub-surface and/or internal oxidation.