Self-healing effect of ceria electrodeposited thin films on stainless steel in aggressive 0.5 mol/L NaCl aqueous solution

Abstract The self-healing effect of electrochemically deposited CeO 2 -Ce 2 O 3 films on stainless steel OC404 (SS) in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after covering it with CeO 2 -Ce 2 O 3 layer and thermal treatment (i.e. potential of the system CeO 2 -Ce 2 O 3 /SS t.t. ), was shifted sharply to a considerably more positive value, while the corrosion current was reduced noticeably. The X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) analyses on the observed scratched surface area of the system CeO 2 -Ce 2 O 3 /SS t.t. , after exposure of investigated specimens to 0.5 mol/L NaCl corrosion media, showed partial accumulation of ceria, as well as remarkable increase in the concentrations of oxides of Al, Cr and Fe, on the mechanically revealed steel surface. On the basis of the obtained results one could conclude that the secondary passive oxide/hydroxide films, formed after a definite time interval of exposure to corrosion media, acted as barriers, hindering the corrosion processes in active zones. A hypothesis was put forward about the mechanism of self-repairing oxide layers on the steel surface and their corrosion protection effect respectively.