Development of Nanostructure Multilayer Co-Ni Alloy Coatings for Enhanced Corrosion Protection

Nanostructure multilayer alloy coatings (nmac) of co-ni were developed oncopper in layered manner using different current pulses. nmac of co-ni was depositedgalvaostatically from acid sulphate bath under different combination of cyclic cathode currentdensities (cccd’s) and number of layers. corrosion behaviors of coatings were evaluated in1 m hydrochloric acid, as representative corrosion medium. potentiodynamic polarizationand electrochemical impedance spectroscopy (eis) study revealed that nmac (co-ni)2.0/4.0/6.0/60/three exhibits~160 times better corrosion resistance than monolayer coating,deposited from same bath for same time. better corrosion protection was attributed to theincreased effect of interface, arising from the exceptional thinness of the layers. ascomposition of alloys in successive layers were varied, consequent to the deposition currentdensity (c.d.), the change in phase structure of the deposits were observed, confirmed byx-ray diffraction (xrd) study. layer formation and surface after corrosion tests wereexamined by scanning electron microscopy (sem) and optical profilometer, and reasonsresponsible for better protection were analyzed.