Characterization of corrosion products formed on the surface of carbon steel by Raman spectroscopy

Corrosion of carbon steel in seashore salty soils containing 10, 20, and 34 wt% (saturated) water was investigated. The corrosion rate was measured and corrosion products were analyzed using Raman spectroscopy. It was found that carbon steel in the soil with 10 wt% water content had the largest corrosion rate and the corrosion was dominated by localized corrosion. The corrosion rate drops dramatically and turns to be general corrosion with increase of water content. The corrosion products in the soil with 20 and 34 wt% water content are mainly composed of alpha-FeOOH, while in the soil with 10 wt% water content, the products show a delaminated structure of two layers with the inner layer mainly consisting of alpha-FeOOH and the outer layer composed of Fe2O3 and Fe3O4. Copyright 2008 John Wiley & Sons, Ltd.