Influence of temperature and potential range on Zn-Ni deposition properties formed by cyclic voltammetry electrodeposition in chloride bath solution

Abstract

AbstractThis paper describes the study of electrodeposition process by cyclic voltammetry for Zn-Ni bimetallic coating on the X52 carbon steel substrate. Prior to the deposition at the bath temperatures of 25°C, 40°C, and 60°C, investigations were carried out to find the optimum potential range for zinc-nickel coatings with respect to the Ag/AgCl reference electrode. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) was used for surface morphology and elemental composition studies. The corrosion rate of the deposits was studied using the linear polarization resistance (LPR) method by immersing the samples (with and without coating) into 3.5% NaCl solution for 24 h. SEM and EDX results showed that the bath temperature has affected the formation of the microstructures and composition of coating. In addition, micro-cracks, nickel content, mobility of ions and compactness of microstructure increased by raising the bath temperature used for electrodeposition. The corrosion rate obtained from the LPR method can be correlated with the SEM/EDX analysis. The coating deposited at the temperature of 60°C including more content of nickel and micro-cracks led to lower corrosion resistance compared to the coating deposited at the bath solution temperatures of 25°C, 40°C, and non-coated X52 steel. Based on the results, the Zn-Ni coating deposited on the X52 steel substrate in the bath solution at 40°C presented the best performance due to more suitable achievements of microstructure compaction, composition, microcracks, and corrosion resistance observations.