Studies on Pitting Corrosion of Pulsed Electrodeposited Nanocomposite Coating

Present work pertains to studies on the effect of pulsed current waveforms of rectangular and triangular in the formation of nickel metal matrix and Zirconium titanium oxide nanocomposite coating and its pitting corrosion behaviour. Zirconium titanium oxide nanoparticles are synthesized via sol-gel route and characterized by XRD and FESEM with EDAX. Pulsed electrodeposition was carried out using nickel electrolyte watts bath with suspended Zirconium titanium oxide nanoparticles on the mild steel substrate. Surface morphology of the coating was studied using scanning electron microscopy. Phase identification and particle size were determined using X-ray diffraction. Potentiodynamic polarization test was used for studying pitting corrosion behaviour of nanocomposite coating. The hardness of the coating was measured with Vickers hardness testing. The results have shown that the rectangular wave pulse at 50% duty cycle produced higher hardness and it may be due to the finer grain size of the deposited coating obtained with the rectangular waveform. Increased duty cycle variable from 10% to 50% in both the waveform enhanced the peak current density leading to higher hardness of the coating. The highest corrosion resistance was obtained with the triangular waveform with a relaxation time of 10% duty cycle at 10 Hz frequency. Hence present work established that a waveform and duty cycle of pulsed currents strongly influences the corrosion behaviour of nanocomposite coating.