Effect of electroplating parameters on properties of Zn–nano-TiO 2 composite coatings

Abstract

In this paper, Zn–nano-TiO₂ composite coatings were deposited on the mild steel substrate. Coatings were produced by electroplating method from sulphate bath in which nanosized TiO₂ particles were suspended. The chemical composition and surface morphology of coatings were investigated using energy dispersive spectroscopy and scanning electron microscopy respectively. Corrosion behaviour of the coatings was studied in 3·5 wt-% NaCl solutions, and their microhardness was evaluated through Vickers microhardness test. According to the results, the parameters of current density, particle concentration in the solution and temperature were optimised with respect to TiO₂ content in the composite coatings. The optimised current density, particle concentration and temperature of the bath were found to be 3 A dm⁻², 5 g L⁻¹ and 40°C respectively. Accordingly, an increase in the amount of TiO₂ particles in the composite coatings increases the hardness of composite coatings but did not have harmful effects on corrosion resistance.