A study of the corrosion products of mild steel in high ionic strength brines

The corrosion layer on steel surfaces that formed after exposure to waste i solation pilot plant (WIPP) brines under anoxic conditions was characterize d for chemical composition, thickness and phase composition. The chemical c omposition of the corrosion layer was determined both by X-ray photoelectro n spectroscopy (XPS) and by chemical analysis of acid solutions used to rem ove the corrosion layer. Atomic force microscopic (AFM) images indicated th at the brine-corroded surface layer shows extensive granulation along the c ontours of the steel surface that is characteristic of sharp polishing mark s. The corrosion layer seemed to be porous and could be dissolved and detac hed in dilute hydrochloric acid. The corrosion layer appears to be composed of iron oxides with some ionic substitutions from the brines. The 77 K Mos sbauer spectrum recorded for iron powder leached under similar conditions i ndicated the corrosion layer was comprised principally of green rust. Publi shed by Elsevier Science Ltd.