ELECTROCHEMICAL AND SURFACE STUDIES OF THE PASSIVE LAYERS GROWN ON SPUTTER-DEPOSITED NITROGEN STAINLESS-STEEL ALLOYS IN 1M H2SO4 SOLUTION

The passive behavior of nitrogen-free (N-free) and nitrogen-bearing (N -bearing) stainless steel sputtered coatings was studied in a 1M sulph uric acid solution. The influence of nitrogen on the passivation param eters was investigated with respect to metallurgical features. Potenti odynamic measurements show two types of passivation kinetics for coati ngs containing a nitrogen content > 13 at% N. This electrochemical beh avior affects the steady-state of passive film with respect to the coa ting grain size and the polarization applied. X-ray photo-electron spe ctrometry (XPS) analyses were used to understand the compositional cha nges that seem to be induced by chemical dissolution.