Oxidation kinetics and electrical properties of oxide scales formed under exposure to air and Ar–H2-H2O atmospheres on the Crofer 22 H ferritic steel for high-temperature applications such as interconnects in solid oxide cell stacks

A 100 h isothermal oxidation kinetics study for Crofer 22H was conducted in air and the Ar–H 2 -H 2 O gas mixture (p(H 2 )/p(H 2 O) = 94/6) in the range of 973–1123 K. The parabolic rate constant was independent of oxygen partial pressure in the range from 6.2 × 10 −24 to 0.21 atm at 1023 and 1073 K, while at 973 and 1123 K it was higher in air than in Ar–H 2 -H 2 O. The scales consisted of Cr 2 O 3 and manganese chromium spinel with an Mn:Cr ratio dependent on the oxidation conditions. Cross-scale resistance was evaluated with regards to the application of the steel in solid oxide fuel cells using a number of methods, including X-ray diffraction, scanning electron microscopy, confocal Raman imaging and area-specific resistance measurements. • Crofer 22H was oxidized for 100 h in air or Ar–H 2 -H 2 O at 973–1123 K. • Oxidation kinetics approximately obeyed the parabolic rate law. • At 1023 and 1073 K the parabolic rate constants were similar for both atmospheres. • Raman spectroscopy showed differences in scale composition depending on atmosphere.