TITLE:
Corrosion Behavior of Tin-Plated Carbon Steel and Aluminum in NaCl Solutions Using Electrochemical Impedance Spectroscopy
AUTHORS:
B.O. Oni, N.O. Egiebor, N.J. Ekekwe, A. Chuku
KEYWORDS:
Corrosion, models, corrosion rates, carbon steel, aluminum, brine solution
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.7 No.4,
December
20,
2008
ABSTRACT: The corrosion behavior of both tin-plated carbon steel and aluminum (Al 1100) in NaCl
solutions were studied using electrochemical impedance spectroscopy (EIS). The study
objectives were to compare their corrosion behavior in concentrated brine solution, establish the
equivalent electrical circuit diagrams of their corrosion phenomena, and consequently develop
steady-state corrosion models for estimating the corrosion rates in the given solution. The
steady-state corrosion rates for the tin-plated carbon steel increased significantly when the
concentration of NaCl was increased from 1.0M to 1.5M. The increase in corrosion rate of the
tin-plated steel is attributed to reduced charge transfer resistance due to the breakdown of the
surface tin plating at high chloride concentrations. In contrast, there was little incremental
change in the corrosion rates of aluminum when the NaCl concentration was increased from
1.0M to 1.5M. This is attributed to the known formation of a stable, passivating surface oxide
film on aluminum which inhibits corrosion. The surface passivating film did not show any
significant evidence of degradation with increase in chloride concentration. Using MATHLAB
and the experimental corrosion rate data, a mathematical corrosion model was derived for the
two samples to describe their steady-state corrosion in NaCl electrolyte solutions.