An ESCA and Mössbauer study of the oxide layer formed on steel in water containing chromate and chloride ions

Abstract The formation of oxidic layers on steel in chromate solutions was studied by photo-electron and Mossbauer spectroscopy. To simulate more aggressive realistic systems, some chloride ions were added to the solution. The layers formed under these conditions were found to be thicker by an order of magnitude than those formed in the absence of chloride ions. They probably consist of ferric and chromic oxides of the corundum type (Fe 1−2 Cr x ) 2 O 3 , with the Cr : Fe ratio being depth dependent. The oxide layer is subdivided into small regions behaving superparamagnetically. This heterogeneity of the layer is ascribed to the attack by the chloride ions. The structure of the oxides foun…