In situ Raman spectroscopy study of corrosion products on the surface of carbon steel in solution containing Cl- and SO42-

Corrosion products of carbon steel in a simulated solution containing Cl- and SO42- were investigated by in situ Raman spectroscopy with a self-designed device. The results of Raman test and the SEM/EDS analysis of samples in different immersion times indicate that the corrosion products on the surface of the carbon steel consist of double rust layers, i.e. a porous outer layer (lepidocrocite gamma-FeOOH) and a compact inner layer (magnetite Fe3O4). Aggressive ions such as Cl- and SO42- promote corrosion leading to the formation of lepidocrocite gamma-FeOOH. Weight loss vs. time curve was also measured to study the effects of corrosion products. Corrosion products on a parallel sample were tested by Raman spectroscopy in air environment, which shown a distinct result from the one of in situ test. (C) 2011 Published by Elsevier Ltd.