Evaluation of epoxy coatings for protecting aluminum alloy 2024 from corrosion caused by Aspergillus niger
The aim of this study was to assess the potentials of using epoxy coatings for the prevention of fungus-induced corrosion. The metal specimen of interest was the aluminum alloy AA 2024-T3. The main intent was to evaluate the behavior of the organic acid producing fungus, Aspergillus niger (A. niger), towards the epoxy-coated aluminum. Two different types of epoxy coatings were used: a two-part resin and a commercially-available Rust-Oleum Specialty Appliance Epoxy. Due to challenges encountered throughout the length of the project and time constraints, limited quantitative data was obtained. However, from optical and visual data it can be concluded that epoxy does not serve as a sufficient barrier against A. niger and therefore does not provide corrosion protection. The results fall in agreement with literature, which states that epoxy coatings serve as an easy carbon source for the fungus. Although the mechanism via which fungi and other microorganisms contribute to polymeric coating failure is not evident, it has been proposed that the fungus breaks down the long-chain resin into smaller molecules that are able to pass through its membrane and become metabolized (Raaman, Rajitha, Jayshree, & Jegadeesh, 2012). It is also possible that the organic acids or enzymes produced by certain microorganisms lead to selective leaching of coating components and cause the coatings to become unstable, as the degree of ion transport and porosity increases (Little & Lee, 2009).