Study of the corrosion resistance of Zn and Zn-Co alloy electrodeposits obtained from alkaline bath using direct current

The corrosion behavior of Zn and Zn-Co alloy electrodeposits that were obtained from weakly alkaline glycine solutions has been studied. SEM، EDS and XRD were used to study of surface morphology، chemical composition and phase structure of the coatings. Corrosion behavior of Zn and Zn-Co alloy coatings were studied by Tafel polarization experiment in 3. 5 wt. % NaCl solution. The results showed that increasing of current density during deposition، increases cobalt content of the coating. It was also shown that increasing of current density، up to a value، decreases the grain size and further increase in current density increases grain size of the deposit. It was also noticed that corrosion resistance of deposits were highly influenced by the composition and morphology of the coatings. Zn-Co deposit containing 0. 87 wt. % Co showed the highest corrosion resistance due to its single phase and finer structure.