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

• Published in: Journal of rare earths 2015-11, Vol.33 (11), p.1212-1227
• Main Authors: Guergova, Desislava, Stoyanova, Emilia, Stoychev, Dimitar, Avramova, Ivalina, Stefanov, Plamen
• Format: Article
• Language: English
• Subjects: ceria films; Cerium oxide; Corrosion; Media; NaCl水溶液; Oxides; Rare earth metals; rare earths; self-healing effect; stainless steel; Stainless steels; Steels; Surface chemistry; Thin films; X射线光电子能谱; 不锈钢; 扫描电子显微镜; 氧化铈; 电化学沉积; 自愈合; 薄膜
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/S1002-0721(14)60548-2

The self-healing effect of electrochemically deposited CeO2-Ce2O3 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 CeO2-Ce2O3 layer and thermal treatment（i.e. potential of the system CeO2-Ce2O3/SSt.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 CeO2-Ce2O3/SSt.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.