@inproceedings{56e8377287b442e3b4998d4826e6294d,
title = "Transpassive corrosion mechanism of austenitic stainless steels in simulated bleaching solutions",
abstract = "The transpassive corrosion of highly alloyed austenitic stainless steels - UNS NO8904, UNS S31254 and UNS S32654 - was investigated in simulated bleaching solutions containing 0.014 M SO42-, 0.017 M Cl-, up to 0.01 M oxalic acid and up to 0.0025 M diethylenetetraminepentaacetic acid (DTPA), pH 3.0 and 6.0, with conventional and rotating ring-disk electrode (RRDE) voltammetry, as well as electrochemical impedance spectroscopy (EIS). The transpassive oxidation rate of UNS S32654 was found to be much higher than that of the other two alloys. Oxalic acid addition resulted in a significant increase of the transpassive oxidation rate, whereas the addition of DTPA led to a decrease of that rate especially at a pH of 3. The general features of the impedance spectra demonstrate that transpassive dissolution is favoured for UNS S32654 and secondary passivation predominates for the two other steels. A kinetic model of the process is proposed, featuring a two-step transpassive dissolution of Cr via a Cr(VI) intermediate species and taking into account the dissolution of Fe(III) through the anodic film. The model has been found to be in quantitative agreement with steady state current vs. potential curves and impedance spectra. The kinetic parameters of transpassive dissolution have been determined and the relevance of their values is discussed.",
author = "Iva Betova and Martin Bojinov and Timo Laitinen and Kari M{\"a}kel{\"a} and Pekka Pohjanne and Timo Saario",
year = "2001",
language = "English",
isbn = "951-38-5720-4",
series = "VTT Symposium",
publisher = "VTT Technical Research Centre of Finland",
number = "214",
pages = "323--336",
booktitle = "10th International Symposium on Corrosion in the Pulp and Paper Industry, ISCPPI. Vol. 1",
address = "Finland",
note = "10th International Symposium On corrosion in the Pulp and Paper Industry, ISCPPI , 10th ISCPPI ; Conference date: 21-08-2001 Through 24-08-2001",
}