The influence of pulse plating parameters on structure and properties of Ni-W-TiO2 nanocomposite coatings

In the present work, Ni-W-TiO2 nanocomposite coatings were produced on low carbon steel substrates by means of pulse electrodeposition. To this end, the effects of frequency, duty cycle, current type, and presence of TiO2 nano-particles on structure and properties of the coatings were investigated. Microstructure of the coatings and dispersion of TiO2 nano-particles were studied by scanning electron microscopy (SEM). Crystallite size was calculated using X-ray diffraction patterns by the Scherrer equation. Corrosion performance of the coatings in 0.5 M NaCl as the corrosive solution was investigated by the potentiodynamic polarization method. Finally, the micro-hardness of the coatings was assessed using a Vickers micro-indenter. The results indicated that the pulse frequency of 1000 Hz, duty cycle of 60%, average current density of 10 A/dm2, and TiO2 nano-particle concentration of 10 g/L were the optimum plating conditions. The amount of TiO2 nano-particles incorporated into the coating that were produced under the optimum plating conditions was 1.47 wt.%; also, the crystallite size of this coating was 4 nm and the micro-hardness was 780 Hv.