Characterization of passive films on shape memory stainless steels

Passive films formed on three Fe-Mn-Si-Cr-Ni-(Co) shape memory stainless steels (SMSSs) were studied based on polarization tests, EIS, XPS and Mott-Schottky analyses. The test results were compared with those of a type 304 austenitic stainless steel. The results indicated that silicon plays an important role in the passive film properties of Fe-Mn-Si-Cr-Ni-(Co) SMSSs. Anodic passive films formed on Fe-Mn-Si-Cr-Ni-(Co) SMSSs are highly protective and consist of a chromium oxyhydroxide with incorporation of silicon in the chemical form of a silicate. Mott-Schottky analyses suggested that passive films on Fe-Mn-Si-Cr-Ni-(Co) SMSSs are less defective and thicker than those on austenitic stainless steel. (C) 2012 Elsevier Ltd. All rights reserved.