Effect of natural marine biofilms on galvanic corrosion predicted using potentiodynamic polarization curves
- Univ. of Delaware, Lewes, DE (United States). Coll. of Marine Studies
Galvanic corrosion of copper, 1018 steel, 3003 aluminum and zinc coupled in turn to cathodes of stainless steel alloy N08367 was tested with and without natural marine biofilms on the cathode surface. Weight losses were significantly higher, and corrosion currents were up to two decades higher with a biofilm on the cathode surface for anodes of copper, steel and aluminum, but there was no difference for zinc. Results indicate that, in any case where biofilms on the cathodic member of a galvanic couple result in a systematic and significant increase in the reduction current at the mixed potential of the couple, an increase in consumption of the anodic material should be expected. Cathodic reduction currents (vs. controls with no biofilm) were increased at all potentials down to about {minus}900 mV{sub SCE}, resulting in an elevated current capacity capable of increasing the weight loss of anodic materials over a sustained period of at least two months. Biofilms, however, did not increase consumption of sacrificial anodes with potentials equal to, or more active than zinc. Potentiodynamic polarization curves taken from the corroded samples were used successfully to predict the effect of biofilms on galvanic corrosion rates for the materials tested. Weight loss values calculated by Faraday`s law using corrosion currents from the polarization curves agreed well with actual measured values for anodes of steel, aluminum and zinc, although there were some discrepancies for copper.
- OSTI ID:
- 350175
- Report Number(s):
- CONF-980316--
- Country of Publication:
- United States
- Language:
- English
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