International Journal of Chemistry and Material Science Vol. 2(4), pp. 068-073, November 2014 ISSN 2327-5553 ©2014 Academe Research Journals

Full Length Research Paper

Corrosion inhibition of 316L stainless steel in plain tap water

Anaum Nawaz^1,2*, A. Farooq^1,2, K. M. Deen^1,2, A. Inam¹, R. Ahmad¹ and I. H. Khan^1,2

¹Department of Metallurgy and Materials Engineering, CEET, University of the Punjab, 54590, Lahore, Pakistan.

²Corrosion and Corrosion Control Research Cell, Faculty of Engineering and Technology, University of the Punjab, 54590, Lahore, Pakistan.

*Corresponding author. E-mail: anaumnawaz29@gmail.com. Tel: +92-429-9232256; Fax: +92-429-9231159.

Accepted 8 September, 2014

Abstract

The corrosion behavior of 316L stainless steel in the presence of various Cl^- ions concentrations at constant dose of Zinc orthophosphate (ZOP) containing inhibitor was investigated electrochemically by Tafel Scan, Potentiodynamic and Cyclic polarization. These techniques evaluated the probability of pitting to occur and the effect of ZOP inhibitor on pitting resistance. The corrosion inhibition by ZOP was considered due to formation of passive film which obstructed the approach of aggressive Cl^- ions at the surface. The effectiveness of ZOP containing inhibitor was found more pronounced at 100 ppm Cl^- ions concentration than at higher level. Increase in Cl^- ion concentration in solution not only shifted the pitting potential towards negative direction but also adversely affected the inhibitor efficiency which resulted in high corrosion rate.

Key words: Stainless steel, zinc orthophosphate (ZOP) inhibitor, cyclic polarization, Cl^- ions.