Zinccoatings

Zinccoatings are protective coatings that apply zinc to steel or other metals to provide corrosion resistance. They extend the service life of structural members, pipelines, fasteners, and enclosures exposed to moisture, salts, or industrial atmospheres. The term covers hot-dip galvanizing, zinc-rich coatings, and related zinc-based finishes, all relying on zinc's galvanic protection to shield the substrate from corrosion.

Hot-dip galvanizing (HDG) submerges cleaned steel into molten zinc, forming a layered coating of intermetallics and zinc metal. Typical thickness ranges from 45 to 125 micrometers, depending on material, treatment, and standard. Zinc acts as a sacrificial anode; if damaged, adjacent zinc continues to protect exposed steel. A patina of zinc oxide and zinc carbonate develops over time, adding barrier protection.

Zinc-rich coatings consist of high zinc content (often 65–95% by dry weight) in a binder. They are used as primers, repair coatings, or finish coats and typically reach a dry-film thickness of 50–100 micrometers. They provide sacrificial protection and suit situations where galvanizing is impractical or retrofitting is needed. Methods include spray, brush, or trowel, with cure or bake requirements per formulation.

Other zinc-based finishes include electrogalvanizing (zinc electroplating), sherardizing (diffusion of zinc in a rotary furnace), and zinc-rich epoxy or polyurethane primers. The choice depends on environment, geometry, and maintenance. Standards such as ASTM A123/A123M and EN 1461 govern hot-dip galvanizing; zinc-rich coatings follow various regional specifications.

Zinccoatings offer long service life but can be damaged by abrasion, exposing steel. Zinc degrades at elevated temperatures above about 400°C. Inspection is needed to ensure continued protection in harsh environments.