Corrosion mechanisms of mild steel in chloride-rich atmospheres

This work analyses the corrosion mechanisms of carbon steel when exposed to marine atmospheres with very different chloride ion deposition rates. Two extreme situations are described, characterized by a >consolidated rust layer> (at relatively low atmospheric salinities), formed by a diffusion-controlled corrosion mechanism in which the reduction of dissolved oxygen in the aqueous film deposited on the metal is the predominant cathodic reaction, and an >exfoliated rust layer> (at high atmospheric salinities), where the cathodic reaction of hydrogen evolution becomes important, notably accelerating the corrosion process. The research has employed a range of near-surface and bulk sensitive analytical techniques (SEM/EDS, μXRD, and SEM/μRaman) to characterize the corrosion products and rust layers formed.The authors gratefully acknowledge the financial support for this study from the Ministry of Science and Innovation of Spain (CICYT-MAT2008-06649). They would also like to thank the Spanish Meteorology Agency (AEMET) for the data provided on meteorological parameters in the study area.Peer Reviewe