XPS Analysis of Passive Film on Stainless Steel

Abstract

Potentiodynamic, impedance measurements were carried out on 304 stainless steel in 0.5N, 1.0, 2.0 and 5.0 N H 2 SO 4 solutions. X-ray photoelectron spectroscopic [XPS] studies carried out on 304 stainless steel in H 2 SO 4 solutions revealed the existence of CrOOH, Cr 2 O 3 ,-Fe 2 O 3 ,-FeOOH, Mn 2 O 3 , Mn 3 O 4 , MnS, Ni (OH) 2 , Ni 2 O 3 , NiO, sulphides. The passive film found to contain chromium oxide inner layer and the dissolution of iron through it caused the formation of oxides of iron namely-Fe 2 O 3 and-FeOOH. Higher oxides of manganese and nickel are also due to dissolution through the film. Sulphates are reduced to sulphur chemically by the released protons from anodic polarization.