Kinetics of Stainless Steel 441 Initial Oxidation at 600~950oC in Different Oxygen Pressures

Abstract

The reduced operating temperatures of SOFCs makes the possible of using metallic alloys as interconnect. Stainless steel 441 is one of the common studied materials for the interconnect component. The oxidation behavior of a stainless steel 441 in various oxygen pressure atmospheres in the initial 2 hours was investigated gravimetically in the temperature range of 600 ~ 950oC in the present work. And the morphology of the scale surface of oxidized alloy was observed by SEM, and the impacts of oxygen pressure and temperature on the oxidation were examined. The oxidation mechanisms were analyzed by Real Physical Picture model. Different oxidation kinetic processes were found in various exposure temperatures and oxygen pressures. In the case of 900~950 oC in pure oxygen, it obeyed two stages linear rate law. When the temperature was reduced to 600~800 oC in pure oxygen, the oxidation of 441 alloy followed linear-to-parabolic rate law. But only linear rate law was obeyed in the lower oxygen pressure atmospheres at 800 and 900 oC in the initial 2 hours. The kinetic parameters of the alloy oxidation process were given.