Study of zinc coatings on steel substrate attained by two diVerent techniques

The purpose of this work was to identify the influence of different process variables, such as bath temperature, cooling rate, air knives wiping, immersion time, and bath alloy additions, on the morphology and coating thickness attained using two different galvanizing processes: Cook Norteman and Sendzimir. The operational variables were systematically reported for each process. Scanning electron microscopy was utilized to characterize the microstructure of the metallic samples, while impact and bending tests were conducted to assess the adhesion of the coatings. The immersion time emerged as the most critical factor affecting coating thickness, whereas aluminum concentration significantly influenced coating morphology by regulating the formation of Fe–Zn intermetallic phases. At aluminum concentrations lower than 0.09 wt. %, the layers consisted of g, f, d, and C phases. Conversely, higher aluminum concentrations (exceeding 0.16 wt. %) resulted in a thicker g phase layer rich in zinc. Additionally, lamellae composed of Fe, Al, and Zn formed near the substrate-coating interphase. Both coatings exhibited commendable adhesive strength under the same testing conditions.