Electrochemical behaviour of thermally treated aluminium 2024 alloy exposed to B. mojavensis

Abstract

The copper-rich zone plays a key role in understanding the deterioration process of 2024 aluminium alloy. The intermetallic on the surfaces makes this alloy susceptible to both local corrosion and microbial colonization. The adhesion of bacteria on the surface could deteriorate the metallic substrate in a phenomenon known as microbiologically influenced corrosion (MIC). The triggering mechanism of MIC in 2024-T3 is unclear. An electro­chemical study was conducted to determine the influence of the second phase (Al2Cu) on the corrosion of the 2024-T3 aluminium alloy exposed to bacteria. The 2024-T3 alloy was thermally treated to increase the amount of Al2Cu by nearly 67 % on the surface. The bacterium under study was collected from the corrosion products of a Chilean Air Force aircraft. The isolated bacterium was identified by 16S RNA sequencing as Bacillus mojavensis (99.99 %). Results obtained by electrochemical impedance spectroscopy showed a decreased impedance of 2024-T3 and an increased impedance of heat-treated, both samples exposed to bacteria. The increased impedance could be associated with the antibacterial effect due to the high ion release of copper on the surface, which can inhibit biofilm formation and biocorrosion.