Influence of vanillin on the corrosion behavior of Ni-W alloy electrodeposits and its properties

Abstract

A simple and viable electrodeposition technique has been implemented to fabricate nanocrystalline Ni-W electrodeposits from an alkaline citrate bath with variations of vanillin (additive) concentration. The optimization of additive in the bath was substantiated in terms of its corrosion resistance property (evaluated using Tafel polarization and electrochemical impedance spectroscopy). For alloys deposited in presence of additive (100ppm) in the bath, resulted in low corrosion rate (C.R) and high charge transfer resistance (Rct). The enhanced corrosion resistance property (i.e. low C.R and high Rct) was deduced in terms of its homogenous surface morphology (using scanning electron microscope), reduction in crystalline size (using X-ray diffraction study), diminish in surface roughness value (using atomic force microscopy) as compared with that of electrodeposits obtained in the absence of additive. The inclusion of additive in the electrodeposits during electrodeposition, showed a major impact for its significant corrosion resistance property (C.R.−0.12mm/year and Rct-2177.83Ω·cm2). With an increase in the additive concentration in the bath, the corrosion resistance of the Ni-W coating becomes inferior, due to its porous nature and relative decrease in its capacitive behavior at electrode/electrolyte (corrosive) interface.