Effect of protein adsorption on the corrosion behavior of 70Cu-30Ni alloy in artificial seawater

Copper alloys often used in cooling circuits of industrial plants can be affected by biocorrosion induced by biofilm formation. The objective of this work was to study the influence of protein adsorption, which is the first step in biofilm formation, on the electrochemical behavior of 70Cu-30Ni (wt.%) alloy in static artificial seawater and on the chemical composition of oxide layers. For that purpose, electrochemical measurements performed after 1 h of immersion were combined to surface analyses. A model is proposed to analyze impedance data. In the presence of bovine serum albumin (BSA, model protein), the anodic charge transfer resistance deduced from EIS data at E-corr is slightly higher, corresponding to lower corrosion current. Without BSA, two oxidized layers are shown by XPS and ToF-SIMS: an outer layer mainly composed of copper oxide (Cu2O redeposited layer) and an inner layer mainly composed of oxidized nickel, with a global thickness of similar to 30 nm. The presence of BSA leads to a mixed oxide layer (CuO, Cu2O, Ni(OH)(2)) with a lower thickness (similar to 10 nm). Thus, the protein induces a decrease of the dissolution rate at E-corr and hence a decrease of the amount of redeposited Cu2O and of the oxide layer thickness. (C) 2013 Elsevier B.V. All rights reserved.