Corrosion of Bare and Galvanized Mild Steel in Arabian Gulf Environment
ABSTRACT Corrosion performance of bare and galvanized mild steel in atmospheric, soil and splash zone exposure conditions was evaluated
at a Khaleej Mardumah test station (KMTS) in Jubail Industrial City (JIC) located at Arabian Gulf coast. The samples were
exposed for a period of 15months. During the exposure, the environmental conditions were periodically monitored by analysis
of air, soil, groundwater, and seawater samples. The corroded mild steel and galvanized steel samples were examined by SEM,
XRD and XRF to identify the corrosion products and study their surface morphology. Weight loss method was employed to determine
the corrosion rates. The experimental results showed that intense temperature and humidity variations as well as high chloride
and sulfate concentrations in the region result in severe corrosion of bare mild steel especially under the splash zone conditions.
A comparison with the corrosion data for other parts of the world shows that atmospheric and soil environments at the selected
test site are significantly corrosive to mild steel. The splash zone, on the other hand, is much more corrosive to mild and
galvanized steel than the other parts of the world.
Keywordsatmospheric corrosion-galvanized steel-mild steel-rebar-soil-splash zone
Chapter: Corrosion and Corrosion ControlKirk-Othmer Encyclopedia of Chemical Technology, 04/2011; , ISBN: 9780471238966
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ABSTRACT: Energy dispersive X-ray micro-analysis, X-ray diffraction and fluorescence, Auger, X-ray photo-electron spectroscopy and Fourier transform infrared spectroscopy have been used to characterise corrosion products on carbon steel after atmospheric exposure for periods up to 12 months to an industrial environment near the west coast of the Arabian Gulf. The results indicate that atmospheric corrosion starts by the formation of small blisters at discrete locations on the metal surface, presumably the anodic sites. The blister covers are very rich in iron chlorides and contain iron oxyhydroxides, oxides, sulphates and possibly hydroxide. The formation of iron chlorides as the primary corrosion product is only limited to the early stages of blister formation due to the aggressive nature of chloride ions. Chloride formation during later stages may be partially impaired since it requires the inward transport of fresh chloride ions through the then thick rust layer. In contrast, the formation of iron sulphates at the rust-metal interface continues by the acid regeneration mechanism (which leads to the electrochemical mechanism); therefore it is less dependent on the supply of fresh sulphate ions from the surface electrolyte through the growing rust layer.Corrosion Science.
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