The Synergetic Effect of Flow Velocity and Exposing Time on the Electrochemical Behavior of Cu–Ni 90/10 Alloy in Simulating Conditions of Desalination Plant

Abstract

A laboratory investigation has been achieved to study the effect of flow velocity on the corrosion behaviour of Cu–Ni 90/10 alloy immersed in synthetic seawater, at 60 °C which simulates the real condition of desalination industry in the south of Tunisia. Flow velocity was one of major parameters influencing the oxidation process of cupronickel pipe, through its effect on mass transport and corrosion rate. This influence has been examined on a laboratory scale by means of electrochemical techniques like: Potentio-dynamic polarization, electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR). Results show that the flow velocity has a significant influence on corrosion rate, compared to static immersion. This effect was confirmed by means of corrosion current density (icorr) increase and polarization resistance Rp decrease with exposure time, as indicated by LPR and EIS measurements. Corrosion was attributed to the film deterioration by the erosion corrosion phenomena, caused essentially by hydrodynamic conditions. Indeed, at stagnant condition, the substrate proves a higher corrosion resistance due to the stability of the protective layer.