Electrofabrication of nanostructured multilayer coatings for better corrosion protection

In an effort to improve the corrosion resistance of monolayer Zn–Ni alloy coatings, nanostructure multilayer coating (NMC) has been developed using a pulsed current. Successive layers of alloys with alternately changing compositions were deposited on mild steel (MS) by making the cathode current cycle between two values during deposition. Multilayer coatings with different configurations in terms of composition and number of layers were developed and their corrosion behaviors were studied by electrochemical methods. The effect of cyclic cathode current densities (CCCD's), and the number of layers have been studied, and coating configurations have been optimized for highest corrosion resistances. Multilayer coatings and their degradation during corrosion were confirmed by Scanning Electron Microscopy (SEM) analysis. The improved corrosion resistance of NMC in relation to monolayer alloy coatings, deposited from same bath has been analyzed and results were discussed in terms of increased number of interfaces due to layering.