Corrosion Behavior of Carbon Steel in Reverse Osmosis Permeate of Seawater

The corrosion behavior of carbon steel in Reverse Osmosis(RO) permeate of seawater was studied by carrying out electrochemical measurements and analyzing corrosion products using SEM, IR and XRD. The results show that the corrosion process of carbon steel is controlled by the diffusion process of oxygen, and corrosion products contain γ-FeOOH, Fe3O4 and a little α-FeOOH. The rust layer has double-layer structure, the outer including γ-FeOOH is thin and the inner contains Fe3O4 which is the main proportion of rust layer. Due to the weak acidity of RO permeate, Fe3O4 generates quickly and accumulates on metal surface. Because of the electrical conductivity and fractured surface of Fe3O4 layer, corrosion product layer can′t inhibit corrosion process through hindering the diffusion process of oxygen, and thus the corrosion rate of carbon steel is always high.