Morphology and Corrosion Behavior of Zn-Ni Layers Electrodeposited on Low Alloy Carbon Steel Substrate

The aim of this work is to improve the microstructure, the morphology, the mechanical and the corrosion behavior of Zn-Ni layers electrodeposited on low alloy carbon steel. Some factors such as the nickel concentration in the electrolyte, the electrolyte temperature and the current density are studied and optimized. The efficiency of the layers to protect the low alloy carbon steel against corrosion in HCl solution is also studied in this work. The electrodeposited Zn-Ni layers morphologies and microstructure were investigated by Scanning Electronic Microscopy (SEM) and X-ray diffraction (XRD) respectively. The best deposits of Zn-Ni layers are obtained with 50%-Ni in the electrolyte bath at a temperature of 40 degrees C and a current density of j = 3 A dm(-2). The XRD spectrum showed the coexistence of two phases: delta-phase (Ni3Zn22) and gamma-phase (Ni5Zn21), and a pyramidal morphology is detected by SEM. The lost mass method results showed that the corrosion rate tacked a steady state between 10 and 50% of Ni, and it increased with the increase of Ni amount in the electrolyte bath.