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.

Figure optionsDownload as PowerPoint slideHighlights
► EIS data shows that the anodic passive films afford fairly high corrosion protection.
► The anodic passive films have a substantial Si(IV) content (about 40 at.%).
► Si makes anodic passive films less defective and thicker than those formed on SS 304.