ELECTROCHEMICAL AND LASER RAMAN-SPECTROSCOPY STUDIES OF STAINLESS-STEEL IN 0.15M NACL SOLUTION

Potentiodynamic polarization curves were measured for Type AISI 304 and 316 stainless steels in 0.15M NaCl solution at 4, 20, and 40-degrees-C. The pitting potentials decreased with increasing temperature. A positive effect on the inhibition of passivity breakdown was found in the presence of molybdenum. Surface enhanced Raman spectroscopy (SERS) was carried out on AISI 316 stainless steel to identify the species present on the electrode surface as a function of potential. Results indicate the corrosion films to be highly disordered and most likely to consist of a mixture of the oxides and hydroxides of the component elements of the stainless steel. The potential dependence of the spectra may reflect the behavior of iron, which is the most abundant component in the alloy and most probably in the film.