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Effect of Biomolecules Adsorption on Oxide Layers Developed on Metallic Materials Used in Cooling Water Systems

出版	2014
URL	http://books.google.com.hk/books?id=2Zci0AEACAAJ&hl=&source=gbs_api

註釋This thesis was carried out in the frame of the BIOCOR ITN European project. Metallic materials commonly used in cooling systems of power plants may be affected by biocorrosion. The objective of this work was to study the influence of biomolecules adsorption on the electrochemical behaviour and the surface chemical composition of 70Cu-30Ni alloy, 304L stainless steel and titanium in seawater environments. The interactions between a model protein, the bovine serum albumin (BSA), and the surface of these materials were investigated. After, the influence of tightly bound (TB) and loosely bound (LB) extracellular polymeric substances (EPS) on the oxide layers was evaluated. For that purpose, electrochemical measurements (Ecorr vs time, polarization curves and EIS) were combined to surface analysis (XPS and ToF-SIMS). Comparing to the 70Cu-30Ni alloy in static artificial seawater (ASW) without biomolecules, for which a thick duplex oxide layer is shown, the presence of BSA, TB EPS and LB EPS leads to a mixed oxide layer with a lower thickness. A model is proposed to analyse impedance data obtained at Ecorr. The results show a slow-down of the anodic reaction in the presence of biomolecules with a corrosion inhibition effect by LB EPS, to a lesser extent by BSA and no detrimental effect with TB EPS. On the other hand, the effect of TB EPS and BSA on the passivation behaviour of Ti in ASW and of 304L stainless steel in chloride-free solution was studied. From EIS data, resistivity profiles within oxide films can be plotted. For both materials, oxide layers are more protective with BSA and less protective with TB EPS.