Corrosion behaviour of AA2024 coated with an acid-soluble collagen/hybrid silica sol-gel matrix

Collagen is a potential corrosion inhibitor for aluminium alloy 2024 (AA2024), being derived from fish scale, as confirmed by FTIR analysis. The extracted collagen powder was dissolved within a hybrid silica sol-gel to produce an environmental friendly (green) coating. The corrosion behaviour of the silica sol-gel (SOL) and collagen/silica sol-gel (CSOL) coated AA2024 in 3.5% NaCl solution was investigated by electrochemical impedance spectroscopy (EIS). In addition, the mechanical properties of both coatings were evaluated using hardness, micro-hardness resistance and a cross cut adhesion test. Results showed that collagen improves the corrosion resistance of the coated AA2024, while maintaining the mechanical properties of the non-doped silica sol-gel coating.