Galvalume

Invented by Bethlehem Steel in 1972, the patented Galvalume manufacturing process is similar to galvanization but with aluminum and silicon added to zinc. As the coating dries, patches of aluminum and zinc molecules coalesce into a pattern across the surface of the sheet. The aluminum areas provide corrosion resistance, while the zinc provides galvanization protection. The small amount of silicon helps the coating adhere to the underlying metal, even when cut or rolled into the corrugated shape.

See the reference side-by-side comparison Galvanised MOC compare