Abstract
Under controlled conditions of heat and mass transfer, the inhibitive characteristics of mixed inhibitor combinations on mild steel have been investigated. To achieve such control under turbulent flow, a rotating cylinder electrode system was used to provide quantified hydrodynamics, mass and heat transfer conditions. Potentiostatic polarization experiments were carried out in both the inhibited and uninhibited brackish water solutions, under isothermal and heat transfer conditions.
Under isothermal conditions, the limiting current density values of oxygen reduction in the brackish water followed Eisenberg equation. The presence of heat transfer enhanced the oxygen transfer rate over and above the value under isothermal conditions. The corrosion and passivation potentials, and the passive current density values were a complex function of temperature, flow rate and heat transfer. The anodic current density values increased with the increase in temperature, flow rate and the presence of heat transfer. The anodic dissolution kinetics were activation polarization controlled affected by temperature.
In this investigation, the inhibition of mild steel against corrosion is believed to be due to the oxide and complex films formed on the metal surface. The mixed inhibitor combination showed high protection efficiency under the studied heat and mass transfer conditions.
