Aluminumzinccoated

Aluminum-zinc coated refers to metal substrates, most commonly steel, that are coated with an aluminum-zinc alloy by a hot-dip process. The coating is typically an alloy containing about 55% aluminum and 43–44% zinc, with a small amount of silicon added to improve adhesion. Coatings marketed under trade names such as Galvalume (North America) and Aluzinc (Europe) are widely used for their corrosion resistance and heat reflectivity.

Manufacturing involves passing the steel sheet through a molten bath of aluminum-zinc alloy, sometimes with silicon added. After withdrawal, the coating forms a metallurgical bond with the substrate. Coating thickness is specified by coating weight or micrometers and varies with the intended use, commonly described in terms of g/m2 or equivalent thickness.

Performance characteristics include enhanced long-term corrosion resistance in many environments compared with zinc-only coatings, especially in coastal and industrial atmospheres. The aluminum portion provides a protective barrier, while zinc offers sacrificial protection if the coating is damaged. AZ coatings also offer good formability and higher heat reflectivity, which benefits roofing, cladding, and exterior panels. Potential drawbacks can include susceptibility to white rust if stored damp before painting and the need for compatible pretreatment and paint systems when finishing the surface.

Applications cover roofing and wall cladding, automotive exterior panels, appliances, and other exterior metal products where durability and formability are valued. Standards for aluminum-zinc-coated steel exist in regions around the world, such as EN 10346 in Europe and ASTM A792/A792M in North America, specifying composition, thickness, and mechanical properties. The coating is generally recyclable with the steel during recycling.