Experimental investigations on iron corrosion products formed in bicarbonate/carbonate containing solutions at 90 degrees C

The influence of initial oxygen level and bicarbonate content on iron corro sion was examined during the early stages of a storage at 90 degreesC. The nature of corrosion products formed on iron surface was investigated throug h FTIR, Raman spectrometry and scanning electron microscopy. It has been sh own that high bicarbonate content (1 M) promotes the formation of siderite whatever the initial oxygen level. Decreasing the bicarbonate content (from 0.1 to 0.001 M) will favour the formation of Fe-II(OH-)(x)(HCO3- /CO32-)(y ) species with increasing x values and decreasing y values. Fe-II(OH-)(x)(H CO3-/CO32-)(y) species may suffer a series of transformations into green ru st GR1(CO3) (intermediate species), Fe-II(OH-)(n)(HCO3-/CO32-)(m) gel-like precipitate, magnetite or lepidocrocite depending on the initial oxygen lev eL @ 2001 Elsevier Science Ltd. All rights reserved.