Study of Fe_3Al Corrosion Behavior in- Simulating Marine Biofilm Environment

摘要

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 Fe_3Al 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 Fe_3Al electrodes exposed in simulated seawater. The corrosion process of Fe_3Al 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 Fe_3Al 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 Fe_3Al surface, corrosion potential dropped sharply and the surface oxidative membrane broken when polarization potential reached —0.5 V, indicating that Fe_3Al can be easier corroded by SRB than by other bacteria.