Electrochemical corrosion behavior of industrial pure aluminum in simulated seawater

In order to study the corrosion behavior of aluminum in seawater, corrosion behavior of industry-grade aluminum in simulated seawater is investigated by electrochemical impedance spectroscopy (EIS), immersion test and scanning electron microscopy (SEM). It is found that pitting corrosion of aluminum locates at Fe-rich areas, and the radius of pitting corrosion increases with prolonged reaction period. Dissolution curve of aluminum in simulated seawater can be divided into four parts, including activated dissolution area, transitional area, over-passivation area and passivation area. In over-passivation area, transfer resistance (R_t) decreases with increasing polarization potential, where severe pitting corrosion occurs. However, R_t almost keeps constant with increasing polarization potential in passivation area, where the dissolution of aluminum can be inhibited. It is determined that pitting corrosion of industry-grade aluminum in simulated seawater happens in the potential range of -0.45~-0.65 V, and the passivation potential range locates between -0.75 V and -0.85 V.