Morphological and Structural Characterization of Zn-Ni Electrodeposited Coatings: Effect of Sulfate Bath Parameters

Electrodeposition process was used to obtain Zn-Ni coatings on carbon vitreous from sulfate-based bath containing Sn as additive. In order to deposit a fine grained layer containing about 14 wt% in nickel with single intermediate phase, the effect of baths’ parameters (applied potential (E), temperature, stirring and pH)on microstructure and morphology of these coatings, were studied and discussed. The experimental results revealed that increasing the applied potential from −1.4 V to −1.2 V modified significantly the morphology from typical nodular structure to nodules with the appearance of pellets. Then, applying −1.2 V and heating the electrodeposition solution, promoted the single-phase crystallization (δ (Ni2Zn11)which permitted to obtain the inspected smooth fine-grained structure. In order to increase the nickel content, stirring and adjust pH seemed to be a solution. However, stirring during plating involved a cracked surface with 5.5 wt% Ni, adjust pH to 1.7 required the best surface films appearance eby increasing the Ni content up to 16 wt%.