Facile and eco-friendly synthesis of polyaniline/ZnO composites for corrosion protection of AA-2024 aluminium alloy

In this study, organic/inorganic PANI/ZnO composites with different weight proportions were prepared via a simple and environmentally friendly method consisting of ultrasonication and a solution combustion method using urea as fuel. Powder X-ray diffraction and EDAX were carried out to investigate the structure, crystallinity and chemical composition of the samples. Raman spectra were recorded to provide information about the interactions between PANI chains and ZnO. The grain size and morphology were evaluated by laser granulometry. The anti-corrosion properties of ZnO/PANI composites were evaluated for AA-2024 substrates after coating using the drop-deposition technique and (N-methylpyrrolidone) (NMP) as the solvent. The composite coating was almost stable over a period of 30 days when exposed to an aqueous solution of 3.5% NaCl, as determined by the gravimetric method. The contact angle technique was used to measure the hydrophobicity, which increased to 85° for the coated composite substrate. The potentiodynamic curves showed considerable improvement in the corrosion resistance with increasing ZnO content, and 60 wt% ZnO/PANI resulted in the lowest icorr value with a protection efficiency of 99.99.