The Corrosion Behavior of C-steel, Al-alloy and Pure-Cu in Red Oak Wood Extract: A Comparative Study

摘要

The corrosion behavior of three metals (C-steel, Al-alloy, and Pure-Cu) in the red oak wood extract(ROWE) had been studied using weight loss (expressed as thickness loss), potentiodynamic polarizationand electrochemical impedance spectroscopy. Visual and microscopic inspection of the corrosionsystems was done using optical photography and SEM techniques. The results revealed that the thicknessloss data fit well the kinetic power law relation ( ? = Kt n ). Depending on both values of thickness loss ofone year and the instantaneous corrosion rate, the studied metals gave the following order of corrosion:C-steel ? Al-alloy ? Pure-Cu. Good correlation between this order and the color and clarity of themetal/ROWE corrosion systems was obtained, where C-steel/ROWE showed the highest change in colorand turbidity through the corrosion duration. Pure-Cu gave the lowest value for corrosion rate withexponent n < 0.5 indicating good protective properties for the corrosion product layer which showed acompact structure with no detection for microbial activity. Open structure corrosion layer (n ? 0.5) withmicrobial activity was observed for both C-steel and Al-alloy which distributed generally on the surfaceof the former while locally on the surface of the latter. Various electrochemical parameters wereestimated and discussed. Finally, good agreement between the results obtained from various techniquesconfirming that C-steel gives the highest corrosion rate while the lowest corrosion rate was recorded forPure-Cu.