Accessing the corrosion resistance for metallic surfaces using long-chain fatty acids†

In this study, the corrosion resistance of a metallic surface is provided by a superhydrophobic coating, which can protect it from dirt and water. The aluminium surfaces are modified with different long-chain fatty acids using a simple immersion technique. The modified aluminium surfaces exhibit excellent water-repellent properties with a static water contact angle of more than 150° and a sliding angle of less than 10°. The corrosion resistance of the modified surfaces was measured using a potentiodynamic technique in a 3.5% (w/v) NaCl solution. The Tafel plot shows an enhancement in corrosion resistance with a low corrosion current density and high corrosion potential after modification. The highest E_corr value of −0.7819 V and the lowest corrosion current density of 1.48 × 10⁻⁶ A cm⁻² are found to be for the octadecanoic acid coated sample. Furthermore, the rate of corrosion resistance is analysed based on the length of fatty acids. Additionally, the modified aluminium surface also shows a dirt-resistant nature. The performance of the coated surface was investigated under several operating conditions including elevated temperature, contact with highly acidic and alkaline solutions, and different mechanical tests (surface bending, water jet, tape-peeling, and abrasion using sandpaper), which fulfils the industrial suitability of aluminium after modification.