Scanning electron microscopy and infrared spectroscopic studies of marine atmospheric corrosion products of steel
- UAC, Campeche (Mexico). Programa de Corrosion del Golfo de Mexico
- UNAM, Mexico City (Mexico). Instituto de Fisica
Carbon steel plates were exposed for twelve months to a marine tropical atmosphere. The corrosion products formed were analyzed monthly by using scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). This study shows that during the first months of exposure of low relative humidity (mean value 65%) the corrosion product formed is an amorphous oxyhydroxide. At intermediate ages this product transforms into {gamma}-FeOOH (lepidocrocite) and under conditions of higher relative humidity values (about 75%) at nine to twelve months of exposure the dominant corrosion product is {alpha}-FeOOH (goethite). No magnetite (Fe{sub 3}O{sub 4}) has been detected at any stage by the techniques the authors have employed. This could support the statement that the reduction product of oxyhydroxides is rather a ferrous intermediate, which in subsequent stages would be oxidized to unordered Fe(OH){sub 3} and or amorphous FeOOH. The transformation of these latter products into {gamma} and {alpha} oxyhydroxides by water loss and crystallization would close the reaction cycle of the natural atmospheric corrosion of steel, where Fe(OH){sub 2} replaces Fe{sub 3}O{sub 4} as the reduced state.
- OSTI ID:
- 109928
- Report Number(s):
- CONF-950304--
- Country of Publication:
- United States
- Language:
- English
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