The growth of iron oxide films on carbon steel and platinum surfaces in LiOH and NaOH solutions at 285°C

Abstract

The corrosion products formed on carbon steel exposed to 1 mol/l LiOH and NaOH at 285°C in titanium autoclaves have been investigated using scanning electron microscopic and X-ray diffraction techniques. The effect of galvanically coupling the carbon steel to platinum was also studied. In LiOH both Fe 3O 4 and α-LiFeO 2 were found to form on the carbon steel surface but only α-LiFeO 2 was observed to nucleate on platinum in this solution. In NaOH solution both Fe 3O 4 and FeTiO 3 were identified on the metal surface. Galvanic coupling to platinum decreased the amount of α-LiFeO 2 and FeTiO 3 formed on carbon steel surfaces.