Electrochemical study of Zn-Fe alloy coatings on mild steel for automotive applications

This study investigates the electrochemical behavior of Zn-Fe alloy deposited on mild steel (MS) substrates for automotive applications. The electrodeposition of a Zn-Fe alloy onto MS using an acid chloride bath, with 1,2,4-Triazole as an additive to enhance the uniformity of the deposit. The hull cell method was used to optimize the bath composition and operating conditions. The coatings were produced using electrodeposition at varying current densities, with 3 A∙dm‒2 identified as the optimal current density (CD) for achieving uniform coatings. The microstructural properties, including crystallite size and micro-strain, were analyzed using X-ray diffraction (XRD) and Williamson-Hall (W-H) analysis, revealing a homogenous distribution of crystallite size and strain. The impact of CD on coating features such as hardness, cathode current efficiency (CCE), thickness, and the weight % of metal contents was investigated. The corrosion resistance of the deposit was estimated using the potentiodynamic polarization and electrochemical impedance spectroscopy methods, and the results have been discussed. The structural and morphological properties of the deposit were investigated by Scanning electron microscopy (SEM). The roughness of the deposit was studied by Atomic force microscopy (AFM). The deposits containing Zn and Fe contents were confirmed by Energy-dispersive spectroscopy (EDS). The results suggest that Zn-Fe alloy coatings can provide superior protection for automotive components.