Simulation of Solid-State Growth of Iron Sulfides in Sour Corrosion Conditions

H₂S corrosion is generally assumed to proceed predominantly via a fast direct heterogeneous chemical process, often referred to as solid state reaction. Unlike iron carbonate films, iron sulfides are found to exhibit semiconductive properties. These properties ensue from the imbalance of ionic charge due to the presence of native point defects in the growing film. The inherent semiconductive nature of defective iron sulfides is anticipated to play a crucial role in localized sour corrosion mechanism. Hence, studying the intrinsic properties of iron sulfides is not only a prerequisite to make strides in the fundamental understanding of localized sour corrosion, but is also of great practical relevance. Within the framework of linear irreversible thermodynamics, a numerical model is developed. This model accounts for the growth of defective iron sulfides via multicomponent solid state transport mechanism through a freshly formed thin iron sulfide layer.

Keywords: Sour corrosion; Iron sulfides; Point defects; Linear irreversible thermodynamics; Solid state transport; Numerical model.