A Study on the Influence of the Electroplating Process on the Corrosion Resistance of Zinc-Based Alloy Coatings

Abstract

A comprehensive analysis was conducted to examine the crystal phase composition, surface and cross-section morphology, elemental composition, thickness, and corrosion resistance of coatings. X-ray diffraction (XRD) was employed to investigate the texture and crystal phase of the materials while scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were utilized to assess the surface and cross-section structure. Additionally, electrochemical techniques were employed to evaluate the corrosion performance. Compared to DC electroplating, the corrosion potential of pulsed galvanized ferroalloy alloy coating increased from −1031 mV to −1008 mV, and the corrosion current density decreased from 3.122 × 10−5 A∙cm−2 to 0.321 × 10−5 A∙cm−2. Moreover, the corrosion rate value of the coating obtained by the pulse rectifier (0.386 × 10−5 g m−2 h−1) was lower than that obtained by the DC power supply (3.75 × 10−5 g m−2 h−1). Additionally, pulsed electrodeposition reduced the iron content of the coating by 0.7%, thereby enhancing its corrosion resistance and flatness. The impedance parameters of the zinc–iron alloy coating acquired through the 30% duty cycle monopulser process exhibit superior performance compared to DC electroplating. Evidently, the monopulse coating’s structure enhances crystal packing density, augments coating thickness, improves adhesion to the substrate interface, and optimizes grain distribution uniformity. These factors are crucial determinants of the corrosion behavior exhibited by Ze–Fe coating.