The Corrosion Behavior of Stainless Steels and Copper Alloys Exposed to Natural Seawater

The corrosion behavior of stainless steels, titanium, and copper alloys exposed to flowing Pacific Ocean water was characterized using surface analytical and electrochemical techniques. Biofilm formation on stainless steels and titanium resulted in thin films of bacteria and diatoms that did not cause significant changes of the corrosion Potential E corr or surface properties. Rotating cylinder experiments indicated that both E. and corrosion rates for stainless steels and titanium were independent of mass transport. Four surface layers were identified on copper-containing materials substratum metal and inorganic chloride corrosion layer that contained alloying elements a biofilm and crystalline, spherical phosphate-rich deposits. All copper surfaces were colonized by bacteria independent of alloy composition. The complexity of the impedance spectra for copper-containing materials was attributed to formation of surface layers and contributions of charge transfer and mass transport controlled reactions mediated by the layers. Both anodic and cathodic reactions for copper-based materials were affected by mass transport. Biofouling, Corrosion, Biodeterioration, Electrochemistry.