Electrolytic Coating Process

U. S. Steel Electrolytic Zinc and Zinc-Iron Alloy Coated Sheet products are manufactured through the CAROSEL® process, an innovative technology that applies zinc and zinc-iron alloy coatings on high-quality steel sheets. The objective of this technical bulletin is to provide a comprehensive overview of the electrolytic coating process. The methodology described involves feeding steel sheets from coils into an electrolytic cleaning unit followed by a meticulous series of processing steps, including rinsing, pickling in hydrochloric acid, and pre-wetting with a plating solution. The sheets are then coated in large-diameter rubber/metal conductor rolls within a plating cell, where electric current facilitates the deposition of zinc or zinc-iron alloys onto the steel surface. Results demonstrate that adhesion is achieved through atomic bonding and is contingent upon a pristine, oxide-free surface. The final coating thickness is regulated by the total electric current applied across the plating cells, ensuring consistent quality. After the coating, the sheets undergo thorough rinsing, drying, and inspection, with options for oiling or prelubrication to prevent staining during storage. This process ensures that the coated steel sheets meet high-quality surface finish requirements for various applications.