Evaluation of microbiologically influenced corrosion inhibition using electrochemical noise analysis

Microbiologically influenced corrosion inhibition (MICI) has been observed for Al 2024, mild steel and cartridge brass when an artificial seawater (AS) solution containing growth medium was contaminated by bacteria. Impedance data clearly showed that pitting did not occur under these circumstances for Al 2024. For mild steel corrosion rates were decreased significantly. For brass corrosion rates were also greatly decreased and tarnishing was not observed. Analysis of electrochemical noise data obtained for the three materials in AS with and without growth medium did not reveal significant changes due to MICI except for an increase of the noise resistance Rn and a parallel shift of the current power spectral density plots to lower values for Al 2024 and mild steel. The observed increase of Rn was mainly due to a significant decrease of the standard deviation of the current fluctuations.