Protection of Corrosion of Carbon Steel by Inhibitors in Chloride Containing Solutions

Abstract

In the first part of this study, the inhibitor effect of single, binary and  ternary mixture of chromate, molybdate, nitrite, tetraborate, ortophosphate, benzoate, acetate, ascorbic acid on  the corrosion of carbon steel was investigated. Experiments were carried out in  neutral aqueous solution containing 100 ppm Cl- at room temperature. The current-potential curves were obtained by potentiostatic (1mV/s) method and the corrosion rates were determined by the extrapolation of the Tafel slope of the cathodic polarization curves method and linear polarization method. In the second part, the inhibitor effect of some one component, binary and ternary inhibitor blends was investigated depending on the temperature (30, 40, 50^oC) and pH (5, 7, 9). The inhibitor effects were found to be %95 for solutions containing 50 ppm nitrite. Of all inhibitor systems tried, chromate-molibdate and chromate- nitrite- molibdate was found to be the most effective binary and ternary inhibitor blends, the effectiveness of which is  equal to that of sodium chromate, sodium nitrite, sodium molibdate that alone and used at a high level.

 

Key Words: Corrosion, Inhibitor, Carbon Steel

Keywords

• -

Chloride Containing Solutions

Abstract

References

1. Srivastava, P.K., Kapse, G.W., Patvardahan, A.K. and Metha, M.L., “Effect of Sodium Nitrite Inhibitor on the Corrosion Behavior of Cold Torsion Twisted Mild Steel in Neutral Chloride Solutions”, Corrosion- Nace, 37, 16-21, 1981.
2. Marshall, A., Greaves, B. and Everrit, D.M, “Low Nitrite Inhibitor Treatment For Cooling Systems” Materials Performance, 45-50, 1986.
3. Stranic, M.A., “The Corrosion Inhibition of Metals by Molybdate Part 1 Mild Steel”, Corrosion-Nace, 40, 296-302, 1984.
4. Oguzie E. E., Unaegbu C, C. N. Ogukwe , B. N. Okolue and A. I. Onuchukwu ,“Inhibition of mild steel corrosion in sulphuric acid using indigo dye and synergistic halide additives”, Materials Chemistry and Physics, 84, 363-368, 2004.
5. Trinh Anh T., Nadine P., To Thi Xuan H., Yves H. and Bernard B., “Study of the synergistic effect observed for the corrosion protection of a carbon steel by an association of phosphates”, Corrosion Science, 44, 2055-2071, 2002.
6. Al-Borno A., İslam, M. and Haleem, R., “Synergistic Effects Observed In Nitrite-Inorganic Phosphate Inhibitor Blends”, Corrosion, 45, 990-995, 1989.
7. Alexander, D.B. and Maccori, A.A., “Evaluation of Corrosion Inhibitors For Componenet Cooling Water System” Corrosion, 49, 921-928, 1993.
8. Zhao J.M., Zuo Y., “The effects of molybdate and dichromate anions on pit propagation of mild steel in bicarbonate solution containing Cl- “, Corrosion Science, 44, 2119-2130 (2002).

9. Celeste Rabaçal A. and Idalina Vieira A., “Localized corrosion inhibition of 304 stainless steel in pure water by oxyanions tungstate and molybdate”, Electrochimica Acta, 49, 2779-2785, 2004.
10. Bennet P. Boffardi, “Corrosion Control Of Industrial Cooling Water Systems”, Materials Performance , 17-24, 1984.
11. Internet: http://www.prochemtech.com/chem/cwt/cwt.html, 2003.
12. Vukasovich, M.S., and Farr, J. P. G., “Molybdate in Corrosion Inhibitation-A Rewive”, 25, 9-15, 1986.
13. Ilevbare,G. O. and Burstein G. T. “The inhibition of pitting corrosion of stainless steels by chromate nd molybdate ions , Corrosion Science, 45, 1545-1569, 2003.
14. McCafferty, E., “A Competitive Adsorption Model for the Inhibitation of Crevice Corrosion and Pitting”, J. Electrochem. Soc., 137, 3731-3736 1990.