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

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 L-9 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 degrees C.