The Mechanism of Transpassive Dissolution of AISI 321 Stainless Steel in Sulphuric Acid Solution. (24th October 2010)

• Record Type: Journal Article
• Authors: Fattah-Alhosseini, A.; Attarzadeh, N.
• Other Names: Molina Angela Academic Editor.
• Is Part Of: International journal of electrochemistry. Volume 2011(2011)
• Publication Date: 2010-10-24
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; 660.297
• DOI: 10.4061/2011/521384
• Languages: English
• ISSNs: 2090-3529

Abstract

Abstract : The transpassive dissolution mechanism of AISI 321 stainless steel in a 0.5 M sulphate solution was studied using electrochemical impedance spectroscopy (EIS). On the basis of the experimental results, surface charge approach, and point defect model, a kinetic model of the transpassive dissolution process is proposed. The transpassive film is modeled as a highly doped n-type semiconductor—insulator-p-type semiconductor structure. Injection of negative defects at the transpassive film/solution interface results in their accumulation as a negative surface charge. It alters the nonstationary transpassive film growth rate controlled by the transport of positive defects (oxygen vacancies). The model describes the process as dissolution of Cr as Cr (VI) and Fe as Fe (III) through the transpassive film via parallel reaction paths.