Biogenic H2S and extracellular electron transfer resulted in two-coexisting mechanisms in 90/10 Cu-Ni alloy corrosion by a sulfate-reducing bacteria

The microbiologically influenced corrosion (MIC) of 90/10 copper-nickel (Cu-Ni) alloy in the presence of anaerobic Desulfovibrio vulgaris was investigated in this work. The corrosion rate of the alloy varied remarkably with different energy starvation levels, which was attributed to various biogenic H2S concentrations and extracellular electron transfer (EET) by D. vulgaris. The biogenic H2S caused the degradation of passive films generated on the alloy. 20 ppm (w/w) riboflavin accelerated the weight loss of alloy by 52%. The EET routes resulted in localized corrosion of Ni contained in the alloy. Two types of MIC mechanisms coexisted in the 90/10 Cu-Ni alloy MIC by D. vulgaris.