XPS and SEM studies of chromium oxide films chemically formed on stainless steel 316 L

The structure and composition of chromium oxide films formed on stainless steel by immersion in a chromium electrolyte have been studied by SEM and XPS. Cr2O3 crystallites in the range 30–150 nm are fully developed and cover the whole surface. The chemical composition in the depth and the thickness of the oxide layer have been determined by XPS sputter profiles. The oxide film can be described within the framework of a double layer consisting of a thin outer hydrated layer and an inner layer of Cr2O3.