Effect of Surface Treatment on Bio-corrosion in Aluminum Alloy 2024-T3

Bio-corrosion is one of the major problems faced in any engineering/aerospace industry. The present study focuses on understanding the effect of surface treatment on AA2024-T3 on bio-corrosion in aircraft fuel tanks. The microbial attack on aluminum alloy (2024-T3) in aircraft fuel tanks by Pseudomonas aeruginosa was studied. Substrates with (1) chromate-free surface treatment (anodization; 2) Ormosil coatings doped with inhibitors/derivatives known for antimicrobial properties were evaluated for their bio-corrosion protection efficiency as compared to bare coupons. The coupons were immersed in aviation fuel spiked with the test culture. The changes in chemical parameters of test solution like pH were monitored periodically. A probable relationship between number of organisms, changes in pH and the extracellular protein (hypothesized to be produced by organisms) were evaluated. Our studies indicated that pH did not appear to play a crucial role in biofilm formation. Surface morphology of bare and anodized AA2024-T3 coupons before and after electrochemical impedance studies (EIS) was analyzed using FE-SEM. Anodized samples with least i(corr) value of (0.075x10(-6)Acm(-2)) and corrosion rate of (0.12x10(-2)mm/y) after 60days showed distinct corrosion protection than bare and the coated samples. Additional evidence in support of corrosion protection efficiency of anodized was obtained by the biofilm barrier efficiency of 98.94%.