Al content in intermetallic and free zinc on industrial galvanizing sheets

Abstract

The coating of thirty-four industrial galvanized samples from four different lines have been characterized by selective stripping and ICP analysis. It is shown that this analytical procedure gives consistent results. The free Al in the coating is always lower than the effective Al in the pot. This is explained by its diffusion after wiping. The Al picked up in the pot is then always lower than the Al tied up on a solidified and cold product. The difference depends on the sheet thickness which affects the cooling time.