Initial Oxidation Behavior of Ferritic Stainless Steel with Sputtered Mn–Cu Coating

Abstract

Initial oxidation behavior of SUS 430 steel with a sputtered Mn–Cu coating was investigated in air at 800 °C. It was found that Mn was preferrentially oxidized upon thermal exposure from 2 to 10 min. The surface scale mainly consisted of MnO inner layer and Mn3O4 outer layer, although a small amount of Fe was observable in the scale. In addition, CuO developed on the outer surface of the scale after 10 min of oxidation. However, the scale formed on the coated steel upon oxidation for 20–300 min was obviously different from that upon oxidation for 2–10 min. It was composed of a tri-layer containing a top layer of CuO, a middle layer of (Mn,Cu)3O4 with some Fe, and an inner layer of Cr-rich oxide from the outer surface to the interface between scale and steel. With increasing oxidation time, furthermore, the top layer of CuO thickened first and then became thin. The oxidation mechanism was discussed.