The role of Ce ions in electrochemical corrosion of 304 SS in Ce(NO3)(3)center dot 6H(2)O

Abstract

Effects of temperature and potential on the electrochemical corrosion behavior of alloy AISI 304 (UNS S30400) stainless steel were investigated in 3 wt.% cerium nitrate (Ce[NO3](3)center dot 6H(2)O) Solution. With an increase in electrolyte temperature from ambient temperature to 90 degrees C, the corrosion potential of the alloy shifted towards the noble direction, and the resistance to polarization increased due to the formation of Ce-oxide on the electrode surface. The oxide films formed at the open circuit potential (OCP) and a passive potential of 0.4 V-SCE were examined by x-ray photoelectron spectroscopy (XPS). The oxide film formed at 50 degrees C and a passive potential of 0.4 V-SCE consists of mixed oxides of Ce and Cr, whereas that at OCP consists of only Cr oxide. The formation of Cr oxides on the electrode surface was primarily due to the nitrate (NO3-) ions in Ce(NO3)(3)center dot 6H(2)O electrolyte.