Photoelectrochemical monitoring of rouging and de-rouging on AISI 316L

Electrochemical conditions for inducing rouging on surface of AISI 316L in quasi neutral aqueous solution are studied. Potentiostatic polarization at 0.6 Vvs. SSC at pH similar to 7 allowed growth of colourless passive films with a band gap slightly lower than that estimated for the oxide grown on the SS surface by air exposure due to chromium dissolution. Under stronger anodic polarization (U-E = 1.5V vs. SSC) coloured passive films are formed, mainly constituted by iron oxide according to their band gap (E-g = 2.0 eV). Etching in citric acid at 60 degrees C results to be effective in removing rouging. (C) 2017 Elsevier Ltd. All rights reserved.