Effect of Pulse Current Electrodeposition on Structural, Mechanical and Corrosion Resistance Properties of Ni- TiO2 Nanocomposite Coatings

Abstract

Ni-TiO2 nanocomposite coatings were fabricated on mild steel surface by pulsed direct current (PC) electrodeposition. This process was carried out in pulsed current at (1, 10, 50) Hz and a duty cycle (25%, 50%, 75%) respectively, at a minimum current density of 0 & high current density of 4 A/dm2. In this work the properties of nanocomposite films were investigated using scanning electron microscopy (SEM), Vickers microhardness measurements and Tafel polarization tests. The composition of the electrodeposits was analyzed by energy dispersive X-ray analysis (EDX). It was found that the coated surface contained at maximum 16.30 % Ti and 35.48 % O. XRD studies revealed [111] preferred orientation. Hardness increased from 560.4 Hv for Ni-TiO2 (F=10 Hz, DC=75 %) nanocomposite coating to 645.7 Hv for Ni-TiO2 (F=10 Hz, DC=25 %) nanocomposite coating. The corrosion resistance of Ni-TiO2 coatings was evaluated by potentiodynamic polarization studies in 3.5 % NaCl solutions. The Pulsed current offer composite coatings with uniform surface, high microhardness and enhanced corrosion resistance significantly for F=10Hz and DC=25 %.