Iron sheet building roofing material cold rolled steel coil color coated galvanized PPGI/PPGL steel coil1

The electrode potential of zinc is negative compared to iron, and it belongs to the anodic coating, which has the protective effect of sacrificing itself. Although the corrosion of galvanized coatings in atmospheric environments varies greatly with climate types (usually severe in marine climates), their lifespan is proportional to the amount of adhesion of the galvanized coating under the same environmental conditions. Figures 4-8-1 show the results published by the American ASTM in the Metal Handbook. It can be seen that to extend its lifespan, the method of increasing the thickness of the galvanized layer can be used. However, within a certain limit thickness, the hot-dip galvanizing process is easy to achieve, and the electroplating process is relatively limited. The thickness of the galvanized layer is extremely thin, generally reaching a maximum of about 18g/㎡. This is also the fundamental reason why color coated steel plates based on galvanized steel plates are not suitable for outdoor construction.