EIS and XPS studies on passive film of AISI 304 stainless steel in dilute sulfuric acid solution

Abstract

Electrochemical impedance spectroscopy and XPS studies on AISI 304 stainless steel in naturally aerated 0.5 M H 2 SO 4 solution were carried out at room temperature. The valuable model of the metal/solution interphase was established, and the reliable equivalent electrical circuits in the solution were presented. The analysis of the chemical composition of passive film on AISI 304 stainless steel was carried out by XPS. The passive film of AISI 304 stainless steel is composed of oxyhydroxides, Fe 2 O 3, FeO, Cr 2 O 3 , NiO, sulfate, sulfite, and sulfide (FeS, NiS). It is reported that the ferrous sulfide film formed on AISI 304 stainless steel in the dilute sulfuric acid solution. The possible process in which sulfuric acid is reduced to sulfite and sulfide is proposed. The galvanic interaction of sulfide inclusions with the base alloy is introduced. Copyright © 2011 John Wiley & Sons, Ltd.