The influence of sulphate‐reducing bacteria on heterogeneous electrochemical corrosion behavior of Q235 carbon steel in seawater

Abstract

In this article, wire beam electrode (WBE) technique, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and X‐ray photoelectron spectroscopy (XPS) were used to investigate heterogeneous electrochemical corrosion behavior of Q235 carbon steel in seawater containing sulphate‐reducing bacteria (SRB). The presence of SRB in seawater results in the change of corrosion form of Q235 carbon steel from uniform corrosion to localized corrosion. Meanwhile, current distribution of Q235 carbon steel surface changes from homogeneity to heterogeneity in SRB medium, which is opposite to the trend in sterile medium. The localized corrosion process of Q235 carbon steel in SRB medium is indicated by increasing anodic area, and it centralizes in some local areas along with increasing of immersion time. In SRB medium, cathodic and anodic areas present different morphological characteristics. The corrosion products film on cathodic area is compact, whereas that in anodic area is loose. The corrosion products of Q235 carbon steel in SRB medium are mainly composed of FeS, FeO, and FeSO4 and it is hard to find the difference in composition between cathodic and anodic areas.