Influence of biofilms growth on corrosion potential of metals immersed in seawater

✍ Scribed by W. Wang; X. Li; J. Wang; H. Xu; J. Wu

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: German
• Weight: 241 KB
• Volume: 55
• Category: Article
• ISSN: 0947-5117
• DOI: 10.1002/maco.200303690

✦ Synopsis

The changes of corrosion potential (E corr ) of metals immersed in seawater were investigated with electrochemical technology and epifluoresence microscopy. In natural seawater, changes of E corr were determined by the surface corrosion state of the metal. E corr of passive metals exposed to natural seawater shifted to noble direction for about 150 mV in one day and it didn't change in sterile seawater. The in-situ observation showed that biofilms settled on the surfaces of passive metals when E corr moved in noble direction. The bacteria number increased on the metal surface according to exponential law and it was in the same way with the ennoblement of E corr . The attachment of bacteria during the initial period played an important role in the ennoblement of E corr and it is believed that the carbohydrate and protein in the biofilm are reasons for this phenomenon. The double layer capacitance (C dl ) of passive metals decreased with time when immersed in natural seawater, while remained almost unchanged in sterile seawater. The increased thickness and reduced dielectric constant of C dl may be reasons.