An Investigation on Passivation of Various Heat Treated Nickel Aluminium Bronze (C95520) Specimens Using LPR, EIS and ZRA Methods

Document Type : Research Paper

Authors

1 School of Metallurgy and Material Engineering, College of Engineering, University of Tehran

2 Department of Metallurgy and Materials Engineering, Islamic Azad University, Tehran South Unit and Iranian Corrosion Association

Abstract

In this paper, heat treated Nickel Aluminium Bronze (C95520) was used as received and exposed to sea water for 75 days. Metallographic investigations were carried out on exposed specimens prepared under as received and heat treated conditions in order to study their microstructures using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive x-ray analysis (EDAX). To determine the resistance of the passive layer on specimen surfaces, an advanced and novel electrochemical noise technique via zeo resistance ammeter (ZRA) together with linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) were utilized. With respect to the passivation potentials extracted from polarization diagrams and polarization resistance (Rp) determined from Nyquist diagrams for all specimens, it was found out that the target sample was under concentration polarization effect. The target sample, coded as sample 14, was heat treated at 675 oC for 45 minutes and normalized in air. The lower starting passivation potential for the target sample indicated a better condition from passivation point of view. Data analysis of electrochemical noise measurements using an evaluation of the last measured 40 potentials and current data of the specimens exposed to sea water for 75 days showed that the corrosion current for as received specimen was found to be twice that of the target specimen. According to the metallographic micrograph, the pearlitic zones in target specimens were attacked much less than similar sites in as received specimen. It was further observed that the corrosion attack on passive layer occurred on selective phases leading to pitting corrosion.

Keywords

References

منابع
[1] Culpan E. A. & Roes G., “Microstructural characterization of cast Nickel Aluminium Bronze”, Journal of Materials Science, Vol. 13, pp. 1647-1657, 1998.
[2] http://www.cda.org.uk/megab2/corr-rs/pub80/sec331.
[3] Lorimer G., lagbal J. & Ridely N ., “Observation of Microstructure and corrosion behaviour of some Aluminium Bronze”, British Corrosion Journal, Vol. 21, pp. 244-248, 1998.
[4] Jahanafrooz A., Hasan F., Lorimer G. W & Ridley N,. “Microstructural development in complex Nickel-Aluminum Bronzes”, Metallurgical and Materials Transactions, Vol. 345, pp. 1951-1956, 2007.
[5] Wood R., Stokes K., Walsh F., Wharton J., Barik R. & Kear G., “The corrosion of Nickel–Aluminum Bronze in seawater”, Corrosion Science, Vol. 342, pp. 3336–3367, 2005.
[6]-Campbell H., “A review of pitting corrosion of copper and its alloys” American National Association of Corrosion Engineering, Vol. 3, pp. 634-636, 1993.
[7] Takenoutic H., Stupnisek L., Marusica K. & Otmacic H.-Curkovic S., “Comparative studies of chemical and electrochemical preparation of artificial bronze patinas and their protection by corrosion inhibitor”, Electrochimica Acta, Vol. 365, pp. 1-33, 2009.
[8] Schussler A . & Exner H. E., “The Corrosion of Ni-Al bronze in Seawater, Protective layer formation and the pasivation mechanism” Corrosion Science, Vol. 134, No .2, pp.1793-1802, 1993.
[9] ASTM, Standard practice for verification of algorithm and equipment for electrochemical impedance measurement, pp. 89-106, 1994 .
[10] Letardi P., “Electrochemical impedance measurements in the conservation of metals”, Journal of Radiation in Art and Archiometry, Vol. 56, pp. 18-39, 2000.
[11] Kear G., Barker B., Stokes K & Walsh F., “Flow influenced electrochemical corrosion of nickel aluminium bronze”, Journal of Applied Electrochemistry, Vol. 245, pp. 1235-1240, 2004.
[12] Habib K., “Zero resistance ammeter of metallic alloys in aqueous solutions”, Electrochimica Acta, pp. 296-301,2007.
[13] Lafront A.M., Ghali E. & Moral A.T., “Erratum to Corrosion behavior of two bipolar plate materials in simulated Pemfc environment by electrochemical noise technique” , Electrochim Acta 52, pp 5079–5085, 2007.
[14] Zhao B., Hua Li J., Gang Hu R., Rong-Gui Du. & Jian Lin Ch., “Study on the Corrosion behavior of reinforcing steel in cement mortar by electrochemical noise measurements”, Electrochimica Acta 52, pp. 3976–3984, 2007.
[15] Cottis R., “Interpretation of Electrochemical Noise Data”, NACE International Corrosion, Vol. 57, pp. 65-85, 2009.
Journal of Petroleum Research
Volume 21, Issue 65 - Serial Number 65
May and June 2011
Pages 18-33

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