Development of superhydrophobic corrosion resistance coating on mild steel by electrophoretic deposition

A superhydrophobic TiO2 coating was prepared on mild steel to protect/increase life span of the steel by a simple one step electrophoretic deposition (EPD) technique followed by post-deposition treatment with methylhydrogen polysiloxane (trade name KF-99) and heat treatment. Superhydrophobicity was developed at some critical concentration (20wt% solution) of KF-99. The water contact angle of bare steel, TiO2 coated phosphated steel substrate (PSS) and TiO2 coated PSS post treated with KF-99 (20wt% solution) were 11°, 41.7° and 160.7°, respectively. The corrosion resistance of the superhydrophobic coating was estimated by Tafel polarization measurement. The potentiodynamic curves clearly demonstrated that the corrosion rate of superhydrophobic coating was an order of magnitude lower than bare mild steel in 3.5wt% NaCl solution. The Ecorr and Icorr values for the superhydrophobic TiO2 PSS coating post treated with KF-99 were −380mV and 0.09μA respectively, compared to −930mV and 120.22μA for bare steel and −820mV and 20.41μA for TiO2 coated (PSS) untreated with KF-99. It clearly shows significant improvement in corrosion resistance properties of the superhydrophobic TiO2 coated PSS. The coating also exhibited very strong adhesion to the surface with a nano-indentation hardness value of 0.5GPa. The superhydrophobic coating with excellent corrosion resistance thus developed is a promising candidate for wide range of industrial applications. •TiO2 coating on steel was obtained by electrophoretic deposition.•The coating was superhydrophobic by post-deposition treatment with KF-99.•The concentration of KF-99 was critical for creating superhydrophobic structure.•The superhydrophobic coating showed superior corrosion resistance.•The coating was very strongly adhered to the surface with a hardness of 0.5GPa.