Synergistic Effect of Sn Doping in TiO2 Nanoparticles as an Additive in Anti-Corrosion Coatings

Abstract

Corrosion is a major problem and protective coatings offer an effective solution. However, organic coatings are often associated with microcracks caused by the evaporation of solvents during coating preparation. This study investigates the use of titanium dioxide (TiO₂) nanoparticles as a coating additive to protect mild steel surfaces. Additionally, doping TiO₂ with tin (Sn) is believed to enhance its properties due to the reduced size of the nanoparticles. These nanoparticles were synthesised using the sol–gel method and subjected to various analyses. The coated mild steel samples were prepared using the dip-coating method and immersed in 3.5 wt.% sodium chloride (NaCl) solution for 30 days. Electrochemical impedance spectroscopy (EIS) and Tafel polarisation showed that the Sn-doped TiO₂ nanoparticles as an additive improved the corrosion resistance, as evidenced by a positive shift in corrosion potential (E_corr) and reduced corrosion current density (I_corr).