Ultrasound Induced Co-Deposition of Ni-Co Alloy for Better Corrosion Protection

Bright, uniform and low cost Ni-Co alloy coatings are highly desired for many corrosion protection applications. Here we demonstrate the that corrosion stability of Ni-Co alloy coatings can be increased to many fold of its magnitude by inducing the ultrasound effect, parallel to the process of electrodeposition. Ultrasound effect of known power density (p.d.) has been affected to bring the modulation in mass transfer process at cathode. Ni-Co alloy coatings with significant change in composition, phase structure and surface morphology have been developed, under ultrasound effect of different p. d. Corrosion performances of ultrasound-assisted Ni-Co alloy coatings have been evaluated by electrochemical methods. Corrosion data revealed that sonolectrodeposited Ni-Co alloy coatings developed at current density (c.d.) and p. d. of, respectively 4.0 Adm^-2 and 1.2Wcm^-2(represented as (Ni-Co)_4.0/1.2) is about 3times more corrosion resistant than its conventional coating deposited at 4.0 Adm^-2(represented as (Ni-Co)_4.0), using same bath. Corrosion protection efficacy of sonoelectrodeposited Ni-Co alloy coatings were attributed to increase of Co content in the alloy, due to change in its limiting c.d. (i_L). Improved corrosion resistance of sonoelectrodeposited Ni-Co alloy coatings has been discussed in the light of changed composition, surface morphology and phase structure, supported by Scanning electronmicroscopy (SEM) Energy dispersive spectroscopy (EDS)and X-Ray diffraction (XRD) study.