Corrosion behavior of electroless Ni-P-TiO2 nanocomposite coatings and optimization of process parameters using Taguchi method

Abstract

This paper reports an experimental study of corrosion characteristics of electroless Ni-P-TiO2 nanocomposite coatings. Coating process parameters are optimized for maximum corrosion resistance based on L9 Taguchi orthogonal design with four process parameters, viz., concentration of nickel source solution, concentration of reducing agent, concentration of TiO2 powder and bath temperature. Corrosion behavior of the electroless Ni-P-TiO2 nanocomposite coatings was evaluated in 3.5 wt.% NaCl aqueous solution by using polarization technique. Scanning electron microscope (SEM) and Energy dispersive X-ray spectroscopy (EDS) analysis were used for studying the surface morphology and chemical composition of the electroless Ni-P-TiO2 nanocomposite coatings. The results showed that incorporation of TiO2 in coating causes increasing of corrosion resistance and improves surface morphology. Finally, optimum conditions were achieved as, 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 of 85 °C.