Preliminary Studies On Corrosion Mechanism And Dechlorination Treatment Of Marine Iron Artifact

The chemical behavior within the occluded cell of marine iron artifact in shipwreck during localized corrosion has been investigated by means of a simulated occluded cell. The rules of pH fall and enrichment in chloride ions in occluded cell were provided. Meanwhile, the simulated occluded solutions in different stages of different pH and chloride concentration were used to study the electrochemical behaviors of occluded cell corrosion. Ferric oxychloride was found in the corrosion product which may be an intermediate phase during the corrosion process for lack of oxygen in occluded cell. This explains why there were different opinions on the presence of ferric oxychloride in the corrosion product on marine iron artifact.Electrochemical impedance technique was employed to study corrosion of marine iron artifact in seawater. Equivalent circuit representing the features of the porous corrosion was proposed to fit the impedance spectra. Moreover, the relationship between corrosion behavior of rusted cast iron and the time of immersion was also discussed. The physical model was proposed to describe the porous corrosion product layer of rusted iron cast. The theory of transmission line was used to study the relationship between characteristics of EIS and the porous layer of rust.The corrosion mechanism of the marine iron artifact salvaged from sea in a wet/dry atmospheric environment is presented according to three stages: wetting, wet and drying period. Chloride ions participate in the corrosion cycle and accelerate the rusting of...