Fungal corrosion behavior and mechanism of deposit-covered aluminum alloy 7075 in marine environment

The corrosion behavior of deposit-covered aluminum alloy 7075 (AA7075) caused by fungus Aspergillus terreus (A. terreus) was thoroughly investigated in artificial seawater aiming to offer some new insights into the under-deposit corrosion mechanism of aluminum alloys in marine environments containing fungi. Electrochemical impedance spectroscopy, polarization curves, wire beam electrodes, and surface analysis were performed. Results indicate that A. terreus can survive beneath the deposit but the counts of sessile spores decline as the increase of deposit thickness, suggesting a poor biological activity of A. terreus beneath the deposit. Both the uniform corrosion and pitting corrosion are accelerated by A. terreus, while the pitting corrosion of AA7075 alloys beneath the deposit derives from a galvanic cell with a small anode and a large cathode. Deposits have a corrosion inhibition effect on AA7075. However, the galvanic effect caused by the bare and deposit-covered AA specimens is obviously enhanced by A. terreus.