Table of Contents
ISRN Corrosion
Volume 2012 (2012), Article ID 515326, 9 pages
http://dx.doi.org/10.5402/2012/515326
Research Article

Improvement in Corrosion Inhibition Efficiency of Molybdate-Based Inhibitors via Addition of Nitroethane and Zinc in Stimulated Cooling Water

Department of Materials Science and Engineering, Faculty of Engineering, Shahid Bahonar University, Kerman 7618868366, Iran

Received 10 November 2012; Accepted 29 November 2012

Academic Editors: S. Caporali and S. Mabbutt

Copyright © 2012 Saeed Mohammadi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

An investigation was conducted to improve the corrosion inhibition efficiency of molybdate-based inhibitors for mild steel which is the main construction material of cooling water systems, using nitroethane as an organic compound beside zinc. In this study a new molybdate-based inhibitor was introduced with the composition of 60 ppm molybdate, 20 ppm nitrite, 20 ppm nitroethane, and 10 ppm zinc. Inhibition efficiency of molybdate alone and with nitrite, nitroethane, and zinc on the uniform corrosion of mild steel in stimulated cooling water (SCW) was assessed by electrochemical techniques such as potentiodynamic polarization and electrochemical impedance (AC impedance) measurements. Weight loss measurements were made with coupon testing specimens in the room temperature for 48 h. Studies of electron microscopy, including scanning electron microscopy (SEM) photograph and X-ray energy dispersive spectrometry (EDS) microanalysis, were used. The results obtained from the polarization and AC impedance curves were in agreement with those from the corrosion weight loss results. The results indicate that the new inhibitor is as effective as molybdate alone, though at one-ninth of the concentration range of molybdate, which is economically favorable.