Elucidating different microbiologically influenced corrosion behavior of copper, 90/10 Cu-Ni alloy, 70/30 Cu-Ni alloy and nickel from the perspective of element content

Abstract

This research examined the varying susceptibility of pure copper (Cu), 90/10 copper-nickel (Cu-Ni) alloy, 70/30 Cu-Ni alloy, and pure nickel (Ni) to microbiologically influenced corrosion (MIC) induced by Desulfovibrio vulgaris, with a focus on the elemental composition of the materials. The results revealed a progressive shift in MIC behavior across these metals and alloys, with increased corrosion severity observed as Ni content decreased. Element Ni improved the corrosion resistance of the alloy while also preventing the growth of microorganisms. Both planktonic and sessile cell counts decreased as the Ni content increased. The corrosion rate, determined by weight loss, followed this order: pure Cu (25.7 ± 3.8 mg·cm⁻², 0.75 mm·y⁻¹) > 90/10 Cu-Ni alloy (9.1 ± 1.4 mg·cm⁻², 0.27 mm·y⁻¹) > 70/30 Cu-Ni alloy (4.3 ± 0.8 mg·cm⁻², 0.16 mm·y⁻¹) > pure Ni (2.1 ± 0.7 mg·cm⁻², 0.06 mm·y⁻¹). The corrosion current density (i_corr) of pure Cu (3.03 × 10⁻⁵ A·cm⁻²) was approximately 20-fold that of pure Ni (1.54 × 10⁻⁶ A·cm⁻²). There was a correlation between the electrochemical and weight loss results. Thermodynamic analysis and experimental results indicated that M-MIC was the primary MIC mechanism for pure Cu. While both M-MIC and EET-MIC were engaged in the MIC mechanisms of 90/10 Cu-Ni and 70/30 Cu-Ni alloys, the predominant mechanism was EET-MIC for pure Ni.