Eco-friendly approach for the fabrication of bio copper based superhydrophobic coating on steel metal and its corrosion resistance evaluation

This study presents an eco-friendly approach for constructing superhydrophobic (S.H.) coatings on steel surfaces. The bio Cu nanoparticles are synthesized using a biogenic process. Two types of coatings, Ni-S.A and Ni-bio Cu-S.A, were developed and characterized. The EDX results confirm the successful fabrication of two distinct coatings on the steel substrate: one involving the modification of nickel with stearic acid, Ni-S.A, and the other involving the modification of nickel with both bio-Cu and stearic acid, Ni-bio Cu-S.A. The SEM results revealed that the S.H. coats exhibit circular microstructures which contribute to the surface roughness. The contact angles of water droplets on the Ni-S.A and Ni-bio Cu-S.A coatings were measured at 158 +/- 0.9 and 162 +/- 1.1, respectively. Chemical stability tests demonstrated that the Ni-S.A coating maintains its S. H. behaviour in a pH range of 3-11, whereas the Ni-bio Cu-S.A coating exhibits excellent chemical stability in a broader range of pH (1-13). The coating's mechanical stability was evaluated through abrasion tests. The Ni-S.A coating retained its S.H. properties even after an abrasion length equal 1100 mm, while the Ni-bio Cu-S.A coating maintained its S.H. behaviour till an abrasion length equal 1900 mm. The corrosion behavior and protective properties of the S. H. coatings were studied via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. The PDP and EIS findings demonstrated that both Ni-S.A and Nibio Cu-S.A coatings significantly reduced the corrosion rate compared to uncoated steel.