Microbiologically influenced corrosion failure analysis of nickel–copper alloy coatings by Aeromonas salmonicida and Delftia acidovorans bacterium isolated from pipe system

The corrosion failure analysis of Ni–Cu alloy coatings in Nutrient Broth medium and in the presence of two bacteria: Aeromonas salmonicida and Delftia acidovorans, isolated from water pipe system, has been studied using electrochemical techniques. According to EIS data, the low Rct values of Ni–Cu alloy coatings after bacteria incubation indicated that the metabolic products maybe accelerate corrosion. In addition the pH values of the medium did not change throughout the experiment; however, after immersion the pH value decreased for two bacteria and caused corrosion. These situations were verified with creviced corrosion with SEM analysis.