Corrosion behaviour of electroless Ni–P–TiO₂ nanocomposite coatings using Taguchi

Abstract

This paper reports an experimental study of corrosion characteristics of electroless Ni–P–TiO₂ nanocomposite coatings. Coating process parameters are optimised for maximum corrosion resistance based on L₉ Taguchi orthogonal design with four process parameters, namely, concentration of nickel source solution, concentration of reducing agent, concentration of TiO₂ powder and bath temperature. Corrosion behaviour of the electroless Ni–P–TiO₂ nanocomposite coatings was evaluated in 3·5 wt-%NaCl aqueous solution using polarisation technique. Scanning electron microscopy and energy dispersive X-ray spectroscopy analysis were used for studying surface morphology and chemical composition of the electroless Ni–P–TiO₂ nanocomposite coatings. The results showed that incorporation of TiO₂ in coating causes an increase in corrosion resistance and improves surface morphology. Finally, optimum conditions were achieved as follows: concentration of nickel source solution, 50 g L⁻¹; concentration of reducing agent, 10 g L⁻¹; concentration of TiO₂ powder, 10 g L⁻¹; and bath temperature, 85°C.

Keywords:

• Ni–P–TiO₂
• Nanocomposite
• Taguchi
• Corrosion
• Polarisation

This research was supported by the Islamic Azad University, Toyserkan Branch, Toyserkan, Iran. In addition, the authors would like to acknowledge the financial support of the Office in Charge of Research of Iranian Nanotechnology Society and the financial support of the Office of Vice Chancellor in charge of research of University of the Islamic Azad of Toyserkan Branch.