Sustainable corrosion protection of aluminium alloys using a bio-based carbohydrate inhibitor

Abstract

AA 6061 aluminium alloy is valued for its high strength-to-weight ratio and corrosion resistance but remains vulnerable to localized attack in chloride-rich environments. This drives the demand for eco-friendly, non-toxic corrosion inhibitors. The synthesis of hexamethylene-1,6-bis(N-D-glucopyranosylamine) (HGA) was successfully accomplished, and its potential as a corrosion inhibitor for AA 6061 aluminium alloy was investigated in a 3.5 % NaCl environment. Initial evaluation involved immersion tests of the alloy in inhibitor-containing saline media. Comprehensive electrochemical characterization was performed using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques to assess the corrosion inhibition performance of HGA. To elucidate the interaction of HGA with the alloy surface, Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy was employed, confirming the presence of functional groups in the protective inhibitor layer. Surface morphology analysis via Field Emission Scanning Electron Microscopy (FE-SEM) revealed a uniform protective film formation, while Energy Dispersive X-ray Spectroscopy (EDX) verified the elemental composition of the inhibitor and corrosion products. A significant reduction in corrosion current density, along with an enhanced polarization resistance of 75,730 Ω·cm², demonstrated the superior corrosion resistance conferred by the HGA film compared to the untreated alloy. Notably, the HGA-coated surface maintained its impedance stability even after 168 h of continuous immersion in 3.5 % NaCl solution, indicating durable and sustained protection. These findings underscore the promise of HGA as a novel, eco-friendly corrosion inhibitor for aluminium alloys in aggressive chloride environments.