Study of Fe₃Al Corrosion Behavior in Simulating Marine Biofilm Environment

Abstract

Calcium Alginate is a kind of natural biopolymer which can be deposited on metal surfaces to form film. In this work, microbe film was simulated by Calcium Alginate gel, according to the natural structure and property of microbe film. Acetic acid, manganese dioxide, and sodium sulfide were added separately in sodium chloride solution to simulate different bacteria culture systems. The corrosion behavior of Fe₃Al was investigated in simulating biofilm environment by open circle potential, polarization curves, and electrochemical impedance. Electrochemical results show that the passivating film formed immediately when Fe₃Al electrodes exposed in simulated seawater. The corrosion process of Fe₃Al in the medium with manganic sediment was mainly dominated by oxygen diffusion. In the simulated environment with acetic acid, the pitting corrosion potential on the surface of Fe₃Al moved towards negative accompanied with the increasing concentration of chlorine ion and the decreasing value of pH. Simulated sulphate reduce bacteria (SRB) accelerated cathodic polarization process of Fe₃Al surface, corrosion potential dropped sharply and the surface oxidative membrane broken when polarization potential reached −0.5 V, indicating that Fe₃Al can be easier corroded by SRB than by other bacteria.

Keywords:

• Electrochemical methods
• Fe₃Al
• Simulating biofilm

ACKNOWLEDGMENTS

This work was sponsored by National Natural Science Foundation of China (No: 59672090 and 50702053) and the Excellent Mid-youthful Scientist Encouraged Foundation of Shandong Province (2006BS04021).