Zincoating

Zincoating refers to the application of zinc to iron or steel surfaces to reduce corrosion. The coating can be applied by several processes, producing a zinc-based layer with varying thickness and properties. The principal purpose is sacrificial protection, whereby zinc corrodes preferentially to extend the life of the underlying metal.

Hot-dip galvanizing immerses cleaned steel in molten zinc to form a thick, metallurgically bonded coating that adheres well to complex shapes and provides durable outdoor protection. Electrogalvanizing deposits zinc electrochemically to produce a thinner, smoother coating suited for precision parts. Sherardizing applies zinc via a diffusion process in a heated container, yielding uniform coatings on small components. Zinc alloys, such as zinc-nickel or zinc-aluminum systems, offer alternative performance in specific environments.

Zinc protects by galvanic action: it is more anodic than iron, so it sacrifices itself to shield the substrate even if the coating is damaged. This sacrificial protection is complemented by a barrier layer that reduces exposure to moisture. Coating performance depends on thickness, uniformity, adhesion, and service conditions. Over time, coatings can wear, crack, or chip, requiring inspection and possible repair or reapplication.

Typical applications include structural steel, fasteners, and outdoor equipment, as well as automotive, agricultural, and electrical components. Standards specify coating thickness, adhesion, and corrosion resistance, with industry guidelines governing hot-dip and electrogalvanized products. Environmental considerations involve waste treatment and energy use, while coated scrap is recovered in standard metal recycling streams.