The reaction of pure, oxygen-free water with carbon steel has been studied at lower temperatures than that at which spontaneous magnetite formation is generally recognized. In a flow-through reactor, mild steel wool was briefly pickled with hydrofluoric acid (pH = 3) to remove any iron oxide. The acid pickle was followed by a continuous flow of pure water for several weeks. Oxidation of the steel by water was monitored by following the iron concentration in the effluent stream. A decrease in the effluent iron concentration over the period of the experiment suggested the development of a magnetite layer on the metal surface. The formation of this layer was observed at various temperatures. The kinetics of film growth most closely followed the widely applied model of Cabrera and Mott.1 

Additional experiments were carried out in the presence of low levels of dissolved oxygen. The concentration of the iron in the effluent stream decreased rapidly upon addition of oxygen. The effluent iron concentration was determined as a function of oxygen concentration. A mechanism is proposed for the effect of oxygen.

Subject
Films, Water, Corrosion rate, Iron, Ferrous ions, Effluent, Deaerated water, Corrosion products, Film formation, Steel, Passivation, Oxygen, Chemical reactions
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1989
Association for Materials Protection and Performance (AMPP)
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